Integrated Pyro SCB Chip

A Dissertation Report on

“Integrated Pyro SCB Chip”

Submitted to the Savitribai Phule University of PUNE, PUNE In partial fulfillment of the requirements for the

Degree of

MASTER OF ENGINEERING (VLSI and Embedded systems)

(2014-2015)

By Pooja Sharma

Exam Seat No. 11819

Under the guidance of

Dr. Virendra Kumar

Prof. Saniya Ansari

DEPARTMENT OF ELECTRONICS AND TELECOMMUNICATION ENGINEERING

GENBA SOPANRAO MOZE COLLEGE OF ENGINEERING, BALEWADI, PUNE-45

GENBA SOPANRAO MOZE COE, Balewadi ,Pune

DEPARTMENT OF ELECTRONICS & TELECOMMUNICATION ENGINEERING

CERTIFICATE

This is to certify that the project report entitled -“INTEGRATED PYRO SCB CHIP” submitted by Ms. Pooja Sharma exam seat no. 11819 is a bonafide work carried out by her under the supervision of Prof. Mrs. Saniya Ansari and Dr. Virendra kumar Verma and it is submitted towards the partial fulfilment of the requirements to Savitribai Phule, Pune University for the degree of Master of Engineering (VLSI and Embedded Systems). Prof. Mrs. Saniya Ansari Prof. Suchitra Jagtap Internal Guide P.G. Coordinator Prof. Neelam Sonawane H.O.D. Principal

G. S. Moze COE, Balewadi, Pune. Dept of E&Tc 2014-15 i

ACKNOWLEDGEMENT

Author is highly greatful to Professor Saniya Ansari , D.Y. Patil School of Engineering, Lohegoan, Pune, for her continuous guidance and inspiration to the successful completion of this work. Author also wants to thank Dr. Virendra Kumar Verma, Joint Director, ARDE, Pune for his support and guidance throughout the project. Author also takes this opportunity to thank Dr. A. M. Sapkal, Head of department, Department of Electronics and Telecommuni- cation for help and support during this work.

Author is also thankful to Dr. K. M. Rajan, Director, Armament R D Establishment, Pune for support and permission to present this work. Authors express their sincere thanks to Shri Kapil Deo, Sc. `G' Associate Director, for the guidance during the course of work.

Pooja Sharma

G. S. Moze COE, Balewadi, Pune. Dept of E&Tc 2014-15 ii

TABLE OF CONTENTS

Contents Pageno.

List of Figures v

List of Abbrevations viii

Abstract ix

CHAPTER 1 INTRODUCTION 1

1.1 Overview 1

1.2 Types of Fuzes 1

1.3 Electroexplosive devices 2

1.4 Safe, Arm and Fire Device 4

1.5 Problem Statement 7

1.6 Objectives 7

1.7 Methodology 8

1.8 Scope 9

CHAPTER 2 LITERATURE SURVEY 10

2.1 Semiconductor Initiators 10

2.2 ESD & RF Protection 11

2.3 Firing circuit 13

2.4 Boost Converter 14

2.5 Safe, Arm and Fire Unit 15

CHAPTER 3 ELECTROEXPLOSIVE DEVICES 19

CHAPTER 4 FUZE 27

CHAPTER 5 MEMS TECHNOLOGY 36

5.1 MEMS Device 37

5.2 Electrothermal MEMS 38

5.3Piezoelectric MEMS 39

CHAPTER 6 SYSTEM DEVELPOMENT 40

G. S. Moze COE, Balewadi, Pune. Dept of E&Tc 2014-15 iii

6.1 Authentication Unit 40

6.2 Delay and Firing Unit 41

6.3 SCB 41

6.3.1 Construction 42

6.3.2 Fabrication 44

6.4 ESD & RF Protection 48

6.4.1 ESD 49

6.4.2 RF 51

6.5 Firing Circuit of SCB 52

6.5.1 Principle of operation of CDU 53

6.5.2 Firing Circuit Description 54

6.6 Booster Circuit 55

CHAPTER 7 HARDWARE DESCRIPTION 58

7.1Circuit Diagram of the Authentication Unit 58

7.2 Circuit Components 59

7.3Delay and Firing Circuit 67

CHAPTER 8 SAFE, ARM AND FIRE DEVICE 78

8.1 Architecture and Principle of operation of the SAF device 78

8.2 Design of Mechanical Arming Function 81

8.2.1 Base 81

8.2.2 Cover 84

8.2.3 Mechanical Screen 85

8.2.4 Inertial Pin 88

8.2.5 Assembly 90

CHAPTER 9 FLOW CHART 93

CHAPTER 10 SIMULATION RESULTS 94

CHAPTER 11 SUMMARY AND CONCLUSION 97

G. S. Moze COE, Balewadi, Pune. Dept of E&Tc 2014-15 iv

LIST OF PUBLICATIONS 99

REFERENCES 100

APPENDIX-I 103

APPENDIX-II 105

G. S. Moze COE, Balewadi, Pune. Dept of E&Tc 2014-15 v

LIST OF FIGURES

Figure no. Figure name Page no.

Figure 3.1: Typical hot bridge-wire electro-explosive device construction 22

Figure 3.2: Exploding foil initiator construction and operation 24

Figure 3.3: Semiconductor bridge initiator 25

Figure 4.1: Structure of fuze 28

Fig 4.2: Mk 53 Proximity fuze for an artillery shell, circa 1945 32

Fig 4.3: SD2 Butterfly bomb circa 1940 - wings rotate as bomb falls,

unscrewing the arming spindle connected to the fuze 33

Figure 6.1: Block diagram of Authentication Unit 40

Figure 6.2: Block Diagram of delay and firing Unit 41

Figure 6.3: Top view and cut view of typical SCB structure 43

Figure 6.4: Top view of SCB 44

Figure 6.5: SCB chip making process 45

Figure 6.6: Stages of functioning of SCB 46

Figure 6.7: SCB chips made on silicon wafer 46

Figure 6.8: Wall formed from grooves 47

Figure 6.9: Capacitor for ESD protection 50

Figure 6.10: Cross section view of TVS chip 51

Figure 6.11: Equivalent circuit for back to back connected diodes 53

Figure 6.11: Capacitor discharge unit for firing of SCB 54

Figure 6.12: Firing circuit for SCB 55

Figure 6.13: Basic of boost converter 56

Figure 6.15: Booster circuit during low period of square pulse 56

Figure 6.16: Booster circuit during high period after startup 57

Figure 7.1: Circuit diagram of setter 59

G. S. Moze COE, Balewadi, Pune. Dept of E&Tc 2014-15 vi

Figure 7.2: PCB layout for setter 60

Figure7.3: 3D model of setter 67

Figure 7.4: Circuit for regulated power supply 68

Figure 7.5: Pin diagram of 7805 69

Figure 7.6: Schematic diagram for Fuzing 70

Figure 7.7: Layer1 circuitry 71

Figure 7.8: Layer1 Top View 72

Figure 7.9: Layer 1 Bottom view 74

Figure 7.10: Layer 1 3D Top view 76

Figure 7.11: Layer 2 3D Bottom view 78

Figure 7.12: Layer 2 schematic 79

Figure 7.13: Layer 2 Top view 80

Figure 7.14: Layer 2 Bottom view (use SCB instead of R1, R2 with TVS diode) 81

Figure 7.15: Pin configuration of ATTINY85 82

Figure 7.16: Functional Block Diagram of ADXL210AQC 83

Fig. 8.1: View of the MEMS SAF device made of three stacked parts 84

Figure 8.2: Operations procedure of the MEMS SAF device (a) in safe mode, (b) mechanically armed, (c) electrically armed and (d) secondary explosive initiation 85

Figure 8.3 (a): Microactuator cavity before the gases are released 86

Figure 8.3(b): Microactuator cavity after the gases are released 87

Figure 8.4: Pressure evolution in the micro actuator cavity

and slide containing the screen 88

Figure 8.5: Pro-E model of Base 89

Figure 8.6: Base 89

Figure 8.7: Pro-E model of Cover 90

Figure 8.8: Cover 91

Figure 8.9: Pro-E model of Mechanical Screen 92

G. S. Moze COE, Balewadi, Pune. Dept of E&Tc 2014-15 vii

Figure 8.10: Mechanical Screen 92

Figure 10.1: Simulation of Authentication unit 93

Figure 10.2: Simulation for Delay and Firing Unit 94

Figure10.3: Capacitor discharge profile 95

Figure10.3: Capacitor discharge profile 95

G. S. Moze COE, Balewadi, Pune. Dept of E&Tc 2014-15 viii

LIST OF ABBREVATIONS

SCB Semiconductor Bridge

EED Electroexplosive Devices

ESD Electrostatic Discharge

RF Radio Frequency

EBW Exploding Bridge Wire

MEMS Microelectromechanical System

SAF Safe Arm and Fire Device

G. S. Moze COE, Balewadi, Pune. Dept of E&Tc 2014-15 ix

ABSTRACT

Micro electromechanical system is the new technology that takes advantage of unique physical properties at micro scale to create mechanical systems with electrical interface using available microelectronic fabrication techniques. This work takes full benefit of this technology and use of it enables improved performance and efficiency. The electronic circuitry provides trigger signals to initiate electro explosive device which is extensively used in military and civil application for initiation of explosive materials. The electro explosive device used is Semiconductor Bridge. As it has high efficiency, less weight, fast functioning time, reduced size, low input energy, low cost, digital compatibility and immune to Electrostatic discharge & radio frequency hazards. In this project Semiconductor Bridge is integrated with Micro electromechanical system based safe, arm and fire device. Here, we have a architecture of Safe, Arm and Fire device that constitute a real breakthrough for safe miniature fuzing device. It combines mechanical arming unit with electrical safety functionality on the same silicon initiator’s chip. The boost converter will boost the voltage from 3V to 30V. Accelerometer attached with microcontroller senses setback force. We have a two layer circuitry one layer is of 0.74*0.68 inches and other layer is of 0.33*0.29 inches.

G. S. Moze COE, Balewadi, Pune. Dept of E&Tc 2014-15 1

CHAPTER 1

INTRODUCTION

1.1 OVERVIEW

SCB is semiconductor bridge which is integrated with MEMS based safe, arm

and fire device pyrotechnically. MEMS is the microelectromechanical system, its

function is to convert electrical energy into mechanical energy. System is designed

with pyro MEMS based electronic fuze.

In military munitions, a fuze is a part of device that initiates function. It is

designed to detonate, or to set forces into action to ignite, detonate or deflagrate,

the charge (or primer) under specified conditions. It contains safety/arming

mechanism, designed to protect the user from premature or accidental detonation. We

provide safety by making the system password protected.

1.2 Types of Fuzes

Time Fuze (time to arm/time to detonate): This device arms after a set period of

time and explodes at the end of a set delay from the time of arming. Either or both

time increments can be setable prior to firing or fixed within the design of the device.

These fuzes are typically used in ammunition and missiles. One current example of a

time fuze is the U.S. Army's M762, now transitioning to production after close to ten

years in development. Another example is MOFA (multi-optional fuze for artillery).

Impact Fuze (time to arm/impact to detonate): The device arms after a set

period of time and detonates on impact. This type of fuze is typically used in

ammunition, bombs and missiles.

Delay Fuzes: The device arms after a set period of time and detonates a set period

of time after impact. This type of fuze is used on ammunition, bombs and missiles.

Proximity Fuzes: The device arms after a set period of time and detonates when

at the closet point of approach to a target. This type of fuze is typically on

ammunition, rockets and missiles.


1.3 Electro explosives devices

Hot Bridge-wire: Hot bridge-wireEEDs have been in use almost since the

discovery of energetic materials. Hot bridge-wire devices use a small piece of wire,

typically tungsten or platinum.The EED spot charge is initiated by applying a current

pulse to the EED. The current pulse heats the bridge-wire and initiates the spot

charge. The spot charge is coupled to other energetic materials that make up the EED

explosive train. The output of the spot charge begins the detonation process.

Exploding Bridge-wire: In this interesting variation on the hot bridge- wire

concept, the bridge-wire material is heated rapidly enough so a shock wave is created

as the bridge-wire material vaporizes. The shock wave amplitude and velocity is

sufficient to couple it to a relatively insensitive energetic material such as

pentaerythrioltetranitrate (PETN).

Because EBW EED system safety is suffciently great, they have been used in

diffussion weapon warheads. Because the wire in the EBW EED initiates the shock

wave in the energetic material, a very specific firing signature is required to cause the

EED to function high order.

Exploding bridge wire based explosive devices are safe but are unsuitable for use

in electronic fuses due to high voltage required for its operation.

Exploding Foil Initiator: The EFI is a miniaturized version of the flying plate

sensitivity test mechanism. The EFI replaces the energetic material used to drive the

flying plate with an electrically initiated exploding metal foil. The EFI is a very high

speed EED and is constructed with low inductance electrical connections. The EFI

has vastly improved system safety over that of systems using both hot bridge-wire and

EBW EEDs. The EFI is a signature specific EFI. The EFI can only detonate when

coupled to the proper firing circuit.

Semiconductor Plasma Initiators: Semiconductor plasma initiators use the heat

transfer characteristics of silicon plasma to initiate energetic materials. These

materials are sensitive to the heat released by the condensing silicon plasma as it

diffuses through the energetic material. Since the energetic material depends on the


plasma temperature and rate of diffusion through the material, the high order function

of a semiconductor initiation mechanism is signature specific.

Semiconductor Junction Ignite: One type of silicon plasma initiator is the

semiconductor junction ignite (SJI). The SJI uses the silicon plasma initiation

mechanism. It provides additional handling and RFI immunity by its unique diode

structure. Electrically, the SJI looks like two schottky diodes connected in series at the

cathodes. To low level signals such as RFI, the schottky diode junctions cannot be

forward biased and act as two capacitors in a series unable to dissipate any power.

However, when the all-fire threshold is exceeded, the schottky diode junctions heat

rapidly generating silicon plasma that can be used to initiate insensitive energetic

materials.

Semiconductor Bridge: Another type of silicon plasma initiator is the

Semiconductor Bridge (SCB). The SCB resembles a bow tie of silicon that has been

vapour deposited on a sapphire substrate. The silicon plasma is generated when the

all-fire signal is delivered to the SCB. If the fire pulse is not delivered quickly

enough, the silicon bow tie opens and does not generate plasma providing RFI and

other small signal immunity.Main needs of igniters, low energy, reliability and safety,

was fulfilled by semiconductor bridges (SCB).

SCB uses heavily doped polysilicon bridge which is much smaller than

conventional bridge-wires. Passage of a current pulse with significantly less energy

than that required for hot-wire ignition produces a plasma discharge in SCB which

ignites the explosive pressed against the bridge, producing an explosive output within

few microseconds.

SCB devices have very wide range of applications. They are being used in airbag

ignition, in rock blasting detonators, and in military igniters and detonators. They are

particularly attractive for applications where only very low ignition energy is

available.

They can also be combined with other microelectronic circuits or can be integrated

on chip with peripheral circuitry which can be manufactured using MEMS

technology.


1.4 Safe, Arm and Fire Device

An Arm Fire (AF) device is a safety device that provides electrical and mechanical

interruption of an ignition train in order to prevent the unintended functioning of a

missile's rocket motor. These devices are used to prevent accidental or inadvertent

ignition of rocket motors during flight or in any usage which could cause an extreme

hazard to personnel or facilities. AF devices incorporate a fail-safe mechanism that

enables the device to remain armed only while power is applied. When power is

removed from the device, they return to the safe position. Safe and Arm (S&A) device

is a safety device which can be fail-safe or which can incorporate a latching

mechanism which enables the device to remain armed after power is removed and can

typically be returned to safe position by applying power. Latching S&A devices are

commonly used to initiate system destruct in the event of a test failure. Fail-safe S&A

devices are typically used for launch vehicle initiation and for rocket motor stage

separation during flight. S&A devices commonly use an Explosive Train (ET) to

transfer energy to another device from the S&A.

S&A and AF devices are essential elements of today's complex launch vehicles,

missiles and weapons systems. These devices must be compact, highly reliable and

satisfy stringent performance requirements. Using traditional manufacturing methods,

current S&A devices are precision electromechanical systems that are typically 4

inches by 4 inches by 3 inches and weigh 3.7 pounds. Today's advanced S&A designs

are 2.25 inches by 2.25 inches by 2 inches and weigh 1.25 pounds. An innovative

design for S&A and AF devices that is based on MEMS (micro-electromechanical

systems) propulsion technology could reduce the size by a factor of ten and reduce the

weight to grams.

The main functions of a SAF device are to keep the device safe, to arm it and to

contain one energetic material necessary for initiating the munition. A MEMS SAF is

not a “sensor” or a miniaturized pyrotechnical initiator, but it combines both sensing

and actuation functions in a very tiny volume and must operate with a high reliability

level.

An electronic safe arm and fire (ESAF) device is a standard feature on most guided

missiles today. As its name suggests, an ESAF device is used to safely arm and

trigger a guided missile Warhead(s). An ESAF device should ensure that the missile


has been launched, has traveled a minimum safe distance, and is operating properly

before the Warhead or Warheads are armed or fired. If the missile has multiple

Warheads, the ESAF device should fire the Warheads at delayed intervals. The

missile launcher has to be confident that the Warhead or Warheads will detonate at

the proper time.

ESAFs and Firing Modules are suitable for a wide range of electronic safe and fire

applications:

Hard target penetrating missiles and munitions

Miniaturized munitions

Tactical missiles

Precision guided munitions

Rockets

Artillery

Mortars

Key Features

MIL-STD-1316 compliant

Redundant safety circuitry and mechanisms

Arming delay timers constructed from dissimilar technologies

Shock-hardened designs, proven to protect during hard target

penetration

Miniaturized packaging for the smallest, lightest ESAFs and FMs in

the industry

Tiny, on-board, shock-hardened data recorder available for integration

into the ESAF or FM circuit card

All ESAFs and FMs designed to detonate through height of burst,

impact, or trigger delay timer

Patented, removable detonator design for full functionality testing

including arming and firing

High-reliability for long-term storage.


Pyrotechnics is the science of using materials capable of undergoing self-contained

and self-sustained exothermic chemical reactions for the production of heat, light, gas,

smoke and/or sound. Pyrotechnics include not only the manufacture of fireworks but

items such as safety matches, oxygen candles, explosive bolts and fasteners,

components of the automotive airbag and gas pressure blasting in mining, quarrying

and demolition. Individuals responsible for the safe storage, handling, and functioning

of pyrotechnic devices are referred to as pyrotechnicians.

Micropyrotechnics can be defined as the integration of an energetic material into a

multi-functional microsystem, for which the thermal, mechanical and chemical energy

released by decomposition can be exploited. The chemical energy can be released by

sublimation, or combustion, or detonation conditions. This approach is promising

because:

1. The concept is very simple: all that is necessary is to know how to

deposit a mass of energetic material and integrate a heating platform at the

same location.

2. The system is flexible: the stored energy and the pressure generated

depend on the volume of energetic material, such that it can be adapted to

various applications.

3. The release of energy or generation of pressure is triggered by

electrical signal and is therefore fully controllable by electronics.

4. A wide variety of usages may be made depending on the application:

for example, decomposition gases can be used to generate a thrust. The

combustion heat can be used directly for local heating and to satisfy very high

energy needs (for example welding, stripping). Combustion heat can also be

transformed into electrical or mechanical energy, or specific gases can be

generated.

Also the point is to be able to insert the energetic materials into the global

microsystem depending on the application. These lead to the following challenges:

1. Optimization of initiation is a crucial point for the progress of this technology.

The objective is to minimize the energy to be supplied to trigger the initiation such

that these systems are compatible with microsystem constraints.


2. The reduction of the dimensions towards the limits of micropyrotechnics, to

make further progress in the integration level, mass and cost reduction.

3. The choice of energetic materials to be integrated. The energetic material is at

the heart of the technology. It must be selected and formulated precisely as a function

of the application and as a function of the expected performances in terms of initiation

and actuation.

4. The choice of architecture and the development of a simple, integratable, robust

and reliable manufacturing and assembly technology.

The airbag is the most well-known application of micropyrotechnics, followed by

the generation of forces which is the most researched use of micropyrotechnics: more

than half of the research papers addressing the applications of micropyrotechnics

focus on micropropulsion. This concerns the development of microthruster arrays for

the space industry and to a lesser degree for the military. Drug injection is also an

application that has generated important research in Europe. Other applications are

emerging and present very interesting and innovative perspectives in this field, such

as fluid microactuating or the production of electrical microgenerators.

1.5 Problem Statement Obtaining an integratable, compatible, low cost energy source providing a

sufficient quantity of easily accessible energy within a miniaturized system has been

an ongoing challenge for decades. Also challenges for functions embodied in a

conventional mechanical arm and fire system to integrate them in small package made

of assembly of different parts are taken into consideration.

1.6 Objective A SAF device is used to safely arm and trigger a guided missile Warhead(s). For

the people that work around explosive weapons, safety is a vital concern that affects

all facets of a weapon's life - from transportation, to storage, to maintenance, to

buildup, to upload, to flight, and to release. To ensure that the weapon is in an

"armed" condition only when desired and in a "safe" condition at all other times is the

function of the safe and arm device, which is an integral part of the weapon's fuse.


A SAF device should ensure that the munition has been launched, has traveled a

minimum safe distance, and is operating properly before the Warhead or Warheads

are armed or fired[5]. MEMS technology has matured to the state where compact and

reliable S&A/AF device designs can be created using well established and

demonstrated MEMS manufacturing processes. Furthermore, these MEMS systems

can be designed, built, tested and flight qualified using existing MEMS design and

manufacturing methods and fabrication infrastructures.

Thus in short the objectives of SAF are:

Integration of sensing elements, actuators, pyrotechnical elements and

safety functions in a very tiny volume with a sufficient reliability level.

Use of electrical micro actuator to move the metallic screen from the

safe position to arm position

Reductions in the size, weight, volume, parts count and cost.

To ensure safety of the warhead through the service life of the munition.

It must arm the explosive, in flight after a safe launch and at a range

from the launching point.

Initiate the warhead at the desired location approximately the target.

Even after storage for years it must function correctly whenever munition is

fired.

Should be rugged enough to withstand various environmental conditions.

1.7 Methodology The literature review regarding the project is done in continuation of

objectives.

The results and conclusion of the papers gives a brief idea of the gaps

in the work up till now. Considering these gaps the work can be decided.

The size and complexity of SAF is one of the major parameter which

can be considered as a main boundary condition.

The designing of S&A is to be done by adopting MEMS technology.

Fabrication of the S&A device is to be done using MEMS fabrication

technology.

Experimentation to check its strength through the impact test.


FEM analysis for the new developed MEMS based S&A device.

1.8 Scope A safe arm and fire device (SAF) constitute a real breakthrough for safe miniature

fuzing device. On the one hand, it takes all the functions embodied in a conventional

mechanical arm and fire system and integrates them in a single 1cm3 package. On the

other hand, it combines a mechanical arming unit with electrical safety functionalities

on the same pyrotechnical initiator’s chip. Integration of good energetic material to

improve the actuation reliability and improve mechanical arming hermiticity is also

considered within the scope of project.


CHAPTER 2

LITERATURE SURVEY

2.1 Semiconductor initiators

Solid state initiator: One of the first semiconductor devices proposed was the

solid state initiator (SSI) patented by L. E. Hollander in 1968 [1]. He used "off the

shelf" grade silicon materials (approximately 0.2-cm resistivity) to produce 50 devices

designed for 28V firing sets and measured function times of less than 20 ms.

(Function time is the interval between the start of the firing pulse and the explosive

output of the component.) The patent also established that the critical temperature at

which the resistivity of semiconductor material drops can be controlled during the

manufacturing of the semiconductor device by appropriate doping of silicon material.

Semiconductor Bridge Initiator: Bickes and Schwarz of Sandia National

Laboratories, Albuquerque, NM, developed the semiconductor bridge in 1984-85 and

received US patent 4708060 in 1987 [2]. SCB Technologies a New Mexico

corporation obtained license from SNL in 1989 for further development as well as

production and commercialization of the SCB. The patent describes the device which

consists of a small doped polysilicon (or silicon) volume formed on a silicon (or

sapphire) substrate. The length of the bridge is determined by the spacing of the

aluminium lands. The lands provide a low ohmic contact to the underlying doped

layer. Wires ultrasonically bonded to the lands permit a current pulse to flow from

land to land through the bridge; the ultrasonic process produces very strong bonds and

is a cost effective procedure. The doped layer is typically 2 m thick; bridges are

nominally 100 m long and 380 m wide. Bridge resistance at ambient conditions is 1;

however, the bridge dimensions can be easily altered to produce other resistances.

Thin Film Bridge: A thin film bridge initiator for initiating explosives include a

thin film resistive element of a selected composition of Nichrome or Tantalum nitride

either of which is evaporated or sputtered upon an alumina substrate. Robert L. Proffit

received US patent for Thin Film Bridge in 1988 [3].


The structure described was very cost effective, reliable, safe and fast. It also

described process of manufacturing several bridge initiators at one time on single

wafer.

Integrated Silicon Plasma Switch: Received by Eldon Nerheim in 1989 [4] the

US patent describes that the switch comprises a silicon substrate on which is formed a

_rst pair of spaced-apart conductive wire bond pads joined by a thin ribbon of

amorphous silicon or poly-silicon material. A high voltage of 2000V is applied across

it and when trigger current of predetermined amplitude is made to flow, a plasma

cloud is created. It utilizes semiconductor integrated circuit techniques in its

manufacturing.

Tungsten Bridge: This 1990 patent of Bickes eliminated the doping process of

Semiconductor Bridge by depositing a tungsten layer over undoped silicon layer [5].

Device operation is same as the doped device due to the formation of tungsten silicide

which acts as dopant. This device exhibited substantially shorted ignition times than

standard metal bridges and foil ignition devices.

Surface Connectable SCB: Martinez-Tovar published patent on surface

connectable SCB in 2000 [7]. It has a metal layer comprised of metal lands and

electrical connectors which terminate in ats electrical contacts on the back surface of

the element. It may also contain back-to-back zener diodes to provide unbiased

protection against electrostatic discharge. When configured as a semiconductor bridge

element, among other uses, finds use as an igniter for an explosive element.

2.2 ESD and RF protection

RF and ESD Insensitive Electro-Explosive Device EED: In this 1992 invention

of Baginski an electro-explosive device (EED) having a layer of zirconium is placed

on the bridge element and explodes into plasma along with the bridge element in

order to ignite a pyrotechnic compound [6]. The substrate using integrated circuit

fabrication techniques and the conductive bridge of the EED is over coated with a

composite overcoat comprising a metal and an oxidizer, which produces a chemical

explosion upon plasma vaporization of the conductive bridge.


The said circuit integration consists of palladium layer, zirconium layer which may

not be there in the conventional processes. Hence the manufacturing of this kind of

integrated chip may not be possible using conventional process.

ESD safety Circuit using Zener Diode: This invention relates generally to

protecting explosive initiators, and more particularly, to a protective Zener diode that

is connected directly across spaced electrically conductive lands of a semiconductor

bridge for activating an explosive initiator [8]. The Zener diode is chosen to conduct

in the backward direction in response to a positive voltage of about 1.1 times

thepredetermined minimum firing voltage. The Zener diode is an integrated circuit

component on the same substrate as the layer and lands.

The said circuit can be fabricated using conventional processes and technology.

The SCB bridge gap for plasma generation should be open for explosive initiation.

The Zener diode can be integrated by designing it for a predetermined breakdown

voltage. In this case the integrated components are only SCB and Zener diode.

High voltage transient protection circuit using back-to-back Zener diodes: A

semiconductor device utilized in a monolithic integrated circuit for protection against

large voltage transients comprises back-to-back Zener diodes. The Zener diodes are

formed in the integrated chip [9]. This invention doesn't describe the application on

any type of EED. This circuit is a general idea to protect any circuit from high voltage

transients.

The result of connecting the back-to-back Zener diode groups in series is to

effectively extend the operating voltage range in the circuit before avalanche

breakdown occurs, without having to make use of additional processing steps. The

operating voltagerange is extended from the former 12 volts to a wider range of about

25 volts by using twopairs of back to back Zener diodes. The said ESD protection

circuit can be fabricated using conventional processes and technology.

Voltage Protected SCB: In 1999, Bernardo Martinez-Tovar published a patent

which describes a semiconductor bridge ignite device having integral voltage anti-

fuse protection. A fusible link or a resistor is deposited in parallel to the device. High


voltage protection is achieved by interposing a dielectric material within the ignite as

controllable anti-fuse.

Pin-to-pin Electrostatic Discharge Protection for Semiconductor Bridges: The

goal of this research is to protect SCB initiators against pin-to-pin ESD without

a_ecting their performance [10]. Two techniques were investigated. In the first, a

parallel capacitor is used to attenuate high frequencies. The second uses a parallel

zener diode to limit the voltage amplitude. Both the 1 F capacitor and the 14V zener

diode protected the SCBs from ESD. The capacitor provided the best protection. The

protection circuits had no effect on the SCB's threshold voltage.

2.3 Firing Circuits

Detonator Firing Element: In 1989, in U. S. Patent 4,819,560 inventors presented

more intelligent initiation device which was based on his prior patent [12]. It relates to

a logic-controlled explosive igniter, more particularly to a semiconductor bridge

igniter mounted on the same semiconductor die as its triggering switch.

It describes logic of shift registers for converting a serial pulse into plurality of

energized parallel outputs and a network that is connected to each output for

providing trigger voltage only when preselected pattern of shift register outputs are

energized. All this logic is integrated on same substrate as of the SCB. It also gives

circuit for electronic time delay. This circuit contains oscillator which starts

generating string of pulses after it receives trigger. A counter will count these pulses

and a comparator compares count value with predetermined value.

Electronic Detonator Delay Circuit: This patent which was received by David

Ewick in 1999. It describes an electronic delay circuit for use in a detonator and has a

switching circuit and a timer circuit. Switching circuit is an integrated, dielectrically

isolated, bipolar CMOS circuit whereas timer circuit is conventional CMOS circuit.

Use of Bi-CMOS switching circuit allows for greater efficiency of energy transfer

from storage capacitor to the semiconductor bridge.

CDU Firing Set: The capacitor was external to the firing set circuit box and was

connected to the circuitry with banana plugs; this permitted to easily change the


capacitor. The capacitances ranged from 1uF to 40uF [13]. For each test we calculate

the energy delivered by the firing set to the SCB. Function times were obtained by a

photodiode that viewed the ash when the unit fired. The times reported are the time

interval from the trigger signal to the firing set to the light ash. Current through the

bridge is monitored with the current viewing resistor (CVR). A 5 V, 10 p trigger fires

the switch which can be an SCR or an FET.

Firing Set: The firing set [14] consists of low voltage capacitor discharge unit

(CDU) with a 50 µF capacitor charged to 28 V (nominal). Because the SCB dynamic

impedance changes significantly during the process that produces the plasma

discharge, two FET switches in parallel are required to discharge the 35 Amp current

pulse into SCB. Small firing set size was needed for this application consequently, the

CDU charge capacitor needed to be a small value.

Therefore, to get the energy output to the desired level, a voltage doubler was used

which allowed to build the firing set in the available volume.

Energetic Unit Based on Semiconductor Bridge: The WO 2012/176198 patent

describes development of energetic unit that has reduced both size and energy

requirement [15]. The energetic unit use Semiconductor Bridge. In this device a

segment of doped or undoped semiconductor matter acts as a bridge between two

conducting lands. When electric potential is applied to the lands an electric current

flows through the bridge creating plasma which ignites an energetic material that is in

contact with or close proximity to the bridge. Purpose of the patent is to provide

miniaturised energetic unit which can be activated by very small quantity of energy

and can be manufactured using techniques of MEMS technology allowing extreme

miniaturization and low expense.

2.4 Boost Converters

DC-DC Boost Converter: This paper presents a design and simulation of DC/DC

boost converter [17]. This system has a nonlinear dynamic behaviour, as it work in

switch-mode. Moreover, it is exposed to significant variations which may take this

system away from nominal conditions, due to changes on the load or on the line


voltage at the input. This paper analyses the equations of a boost converter and

propose a design components and simulation of DC/DC boost converter.

DC-DC Boost Converter with constant output voltage: From a fluctuating or

variable input voltage boost converter is able to step up the input voltage to higher

constant dc output voltage using voltage feedback technique [18]. By this technique

the output of the converter is measured and compared with a reference voltage. The

differential of the compared value will be used to produce a pulse width modulation

signal to control switch in boost converter.

2.5 Safe Arm and Fire unit

Integration of MEMS based safe arm and fire device: Rossi C. in her paper

describes a new architecture of a Safe Arm and Fire device (SAF) that could

constitute a real breakthrough for safe miniature fuzing device[19]. It takes all the

functions embodied in a conventional mechanical arm and fire system and integrates

them in a single 1cm3 package made of assembly of different parts. On the other hand,

for the first time combination of a mechanical arming unit with electrical safety

functionalities on the same silicon initiator’s chip is done. The paper presents the

design, fabrication and test of one miniature SAF device integrating a

micropyrotechnical actuation.

Fabrication, assembly & tests of a MEMS based safe, Arm & Fire device:

Rossi C. in her paper proposed a Safe Arm and Fire device (SAF) that could

constitute a real breakthrough for safe miniature fuzing device[20]. For the first time,

it combines a mechanical arming unit with electrical safety functionalities on the same

pyrotechnical initiator’s chip. It respects the STANAG 4187 norm (1A/W during 5

minutes of not fire) and requires 500mW for ignition.

Micropyrotechnics, a new technology for making energetic microsystems:

review and prospective: Esteve D. reviewed the micropyrotechnics related works.

Micropyrotechnic[21] is the integration of an energetic material into microsystem, for

which the thermal, mechanical and chemical energy released by decomposition can be

exploited. After a state-of-the art of micropyrotechnics and its application to


microsystems, authors tried to identify obvious difficulties and insufficiencies that

may require future work, particularly in terms of the development of new materials,

new modelling tools and new processes for integration into microsystems. A section

is dedicated to the current micropyrotechnic applications including emerging ones. In

conclusion, the perspectives of this discipline are discussed and the authors try to give

some guidelines for future investigations.

Materials, Fabrication and Assembly Technologies for Advanced MEMS

Based Safety and Arming Mechanisms for Projectile Munitions: Robinson C. H.

in his paper outlines the U. S. Army’s technical progress toward realizing a miniature,

inexpensive, mass producible micro-electro-mechanical systems (MEMS)- based

mechanical safety and arming (S&A) device with embedded compatible micro-scale

firetrain for projectile munition fuzes[22]. It illustrates the significant advances in

MEMS S&A design simplification, MEMS metal fabrication, and automated micro-

assembly technology. These advances have taken place since a June 2005 feasibility

demonstration of MEMS S&A in a 20-mm high-explosive air-burst munition for the

developmental Objective Individual Combat Weapon.

Ultra miniature electro-mechanical safety and arming device: Robinson C.H.

describes a ultra-miniature[23], electro-mechanical, MEMS type safe and arming

(S&A) device for medium- or large-artillery rounds, including, three sequenced S&A

interlocks: a setback slider, which is positioned partially within and partially

extending from an arming slider, such that, upon firing acceleration, the setback slider

will compress into a channel within the arming slider (unlocking the 1st interlock);

freeing the arming slider to move toward its arming position under urging of the

round’s spin; a stop and release mechanism formed by a flexible latch arm which

impacts upon a safety catch located within the frame in which the arming slider is

mounted, such that the arming slider is stopped until a release command signal is

initiated by the fuze circuit, triggering a spot charge which generates an expanding

gas wave that flexes the latch arm from contact with the safety catch (unlocking the

2nd interlock), thereby freeing the arming slider to continue its motion into an arming

position (unlocking the 3rd interlock) and aligning the parts of the firetrain within the


device, such that upon signal from the fuze circuit an output charge from the device

will ignite the acceptor charge within the round.

Design of MEMS Electronic Safety and Arming Mechanism for Projectile

Munition: Verma V.K. describes an electronic Safing and Arming Mechanism

(SAM) apparatus disposed in a projectile having a spin axis and a spin rate[24],

including a battery; a power supply board connected to the battery. A firing board

connected to the power supply board includes an accelerometer that is oriented

perpendicular to and disposed a fixed distance from the spin axis. The output of the

accelerometer varies according to the fixed distance from the spin axis and the spin

rate of the projectile. A comparator compares the output of the accelerometer to a

threshold voltage and an output of the comparator is low when the output of the

accelerometer is less than the threshold voltage and the output of the comparator is

high when the output of the accelerometer exceeds the threshold voltage. A rectifier

connected to the output of the comparator; a firing capacitor, the rectifier being

connected between the battery and the firing capacitor whereby when the output of

the comparator is high the comparator saturates a gate of the rectifier thereby allowing

the firing capacitor to charge.

Fabrication of Fuze Micro-electro-mechanical System Safety Device: Liqun

D.U. studied the application of MEMS-based fuze safety and arm devices[25]. The

reduction in volume allows more payload and, thus, makes small-caliber rounds more

effective and the weapon system more affordable. In this paper, a new micro

fabrication method of metal-based fuze MEMS safety device is presented based on

ultra violet (UV)-LIGA technology. The method consists of SU-8 thick photoresist

lithography process, micro electroforming process, no back plate growing process,

and SU-8 photoresist sacrificial layer process. Three kinds of double-layer moveable

metal devices have been fabricated on metal substrates directly with the method. The

smallest dimension of the devices is 40 μm, which meets the requirement of size. To

evaluate the adhesion property between electroforming deposit layer and substrate

qualitatively, the impact experiments have been done on the device samples. The

experimental result shows that the samples are still in good condition and workable

after undergoing impact pulses with 20kg peak and 150μs duration and completely


met the requirement of strength. The presented fabrication method provides a new

option for the development of MEMS fuze and is helpful for the fabrication of similar

kinds of micro devices.

Final characterizations of MEMS-based pyrotechnical microthrusters: The

paper by Carole Rossi ∗, Benoıt Larangot, Denis Lagrange, Amar Chaalane describes

about microthrusters[31]. Within an European project,1 MEMS-based pyrotechnical

devices have been developed. The operational concept is simply based on the

combustion of a solid energetic material stored in a micromachined chamber. One

possible application is the micropropulsion for nanosatellite but other applications can

be addressed as microrocket for military needs.

Arrays built to validate the concept contain 16 Ø1.5mm×1.5mm rockets on

200mm2. After a brief overview of the design and dimension, this paper presents the

final experimentations that permitted to validate the pyrotechnical thrusters concept.

At the millimetre scale, having a successful and reproducible ignition as well as a

sustained propellant’s combustion is a critical point of this technology. That is why,

ignition, combustion and thrust has been experimented with great attention to fully

validate the concept and results are reported in this paper.

A MEMS-based solid propellant microthruster with Au/Ti igniter: K.L. Zhang

in his paper outlines a solid propellant microthruster with Au/Ti igniter[29] is

demonstrated as an improved micropropulsion system for microspacecraft. The new

design provides the microthruster with a high degree of flexibility and integration.

Single microthruster and microthruster arrays have been successfully fabricated using

standard microfabrication technologies. The performance of the solid propellant

microthruster with Au/Ti igniter is also compared with that of a solid propellant

microthruster having a wire igniter.


CHAPTER 3

ELECTRO EXPLOSIVE DEVICES

Electro-explosive devices (EEDs) are single use transducers that convert electrical

energy into either heat or mechanical energy. They do so through a complex process

that liberates the chemical energy stored in the energetic materials comprising the

EED components. EEDs include exploding bridge wire detonators, hot wire

detonators, explosive foil detonators and semiconductor plasma initiators.

A large number of electro-explosive devices contain a small metal bridge-wire

heated by a current pulse from a firing set with nominal output voltages ranging from

one to several tens of Volts. Heat transport is by means of thermal conduction from

the bridge-wire to the exoergic material next to the wire, producing an explosive

output typically measured in milliseconds after the onset of the current pulse. No-fire

(the maximum current that can be applied to the bridge-wire for a period of time

without causing ignition) and all-fire (the minimum current level required for reliable

ignition) current levels are often strongly dependent upon the exoergic material and

the physical construction of the explosive device.

An EED with explosive output can be used to initiate an explosive train. The

explosive output of an EED is relatively small. It must be increased using other

energetic materials in the explosive train with decreasing shock sensitivity and

increasing volumetric energy content. Thus, a small electrical input signal can initiate

an explosive event that moves tons of rock.

Types of EED: (Classification based on output of EED)

EEDs are coupled to systems in various ways. EEDs are initiated by an electrical

stimulus. They then drive a system by means of the EED energetic material reaction.

In many cases, the energetic materials used in an EED are very sensitive to the input

stimuli. Although sensitive, the energetic output from the sensitive energetic materials

is limited. It must be supplemented with other materials to achieve the desired effect.

The EED output may be immediate, 20 to 100 microseconds, or may incorporate a

time delay between the initiation stimulus and EED output, up to several hundred

milliseconds.


Heat output: With active automotive restraint systems, we come into contact with

heat output EEDs on a daily basis. The purpose of a heat output EED is to initiate a

rapid burning process.

In the automotive passive restraint system, the heat output EED initiates sodium

azide pellets that generate combustion products to fill the air bag. The entire airbag

deployment from the time an impact is detected to the time the airbag begins to

deflate must occur within 20 milliseconds to have the desired lifesaving effect. The

stimuli from a heat output EED are hot combustion products and high temperature

particulates. They are coupled to other energetic materials with decreasing sensitivity

and increasing heat and particulate output. Such is the case of the airbag igniter and

solid rocket motor initiators.

Explosive output: Another common use for an EED is to initiate an explosive

train. Explosive trains are used in military ordnance applications and in commercial

mining and demolition applications. A material is said to detonate or explode when a

mechanical shock wave—with suitable amplitude—propagates through a material

initiating a chemical reaction in the material. An explosive material is designed to

upon initiation generate large local pressures in very small time intervals. The

pressure is generated fast enough so that the reaction products do not have sufficient

time to move appreciably before the shock wave propagates further into the explosive

material.

As the shock wave propagates, it begins to attenuate. However, the propagating

shock wave continues to initiate a chemical reaction that creates a localized high-

pressure zone. The high-pressure zone adds energy to the shock wave maintaining its

amplitude. The shock wave continues to propagate until all of the energetic material is

consumed.

An EED with explosive output can be used to initiate an explosive train. The

explosive output of an EED is relatively small. It must be increased using other

energetic materials in the explosive train with decreasing shock sensitivity and

increasing volumetric energy content. Thus, a small electrical input signal can initiate

an explosive event that moves tons of rock.


Mechanical force output: Mechanical force output EEDs come in a variety of

forms. These devices produce motion or a force that can be applied to other

components of a system. The motion supplied by these devices is typically linear.

For example, one force output EED available from a manufacturer is used to

separate a frangible (easily broken) tensile link. The frangible link is separated when

the EED drives a tapered pin into a hole in the link. The hole is located at the fracture

site designed into the link. Under normal operation, the link is loaded in tension such

as by a ventilation shaft fire door. The link is designed such that the load created by

the door does not exceed the tensile strength of the link.

However, when the EED is activated, the force from the expanding gasses in the

EED is coupled to a piston. The piston then drives the tapered pin into the hole at the

necked down portion of the link. The stress caused by forcing the tapered pin into the

hole exceeds the yield strength of the material and causes the link to open. The link’s

opening shuts the ventilation shaft fire door thus preventing toxic gasses from

entering the ventilation system. Force output EEDs are used in other commercial

energetically driven products. Some products are:

• EED driven valves. Intended for high reliability fire fighting equipment used to

protect computer systems.

• Explosive bolts. Used to separate space cargo such as satellites from launch

vehicles.

• Line cutters. Used to release space re-entry vehicle parachutes.

Electrical output: Electrical output EEDs act as single use remotely activated

switches. These switches can contain multiple poles and are typically used to change a

circuit configuration when activated. Electrical output EEDs are not commonly used

in commercial applications. They are used in various ordnance and space systems to

provide system safety.

The electrical output EEDs usually configure a safety critical circuit in a safe

position prior to activation. An example of such an application is in satellite

deployment. Prior to a launch vehicle reaching intended payload deployment orbit, an


electrical output EED may be used to keep all firing energy away from circuits

intended to fire explosive bolts used to deploy payloads. When the launch vehicle

reaches the intended orbit position, the electrical output EED is activated enabling the

explosive bolt firing circuits.

Various electro-explosive devices are as follows:

Hot Bridge-wire: Hot bridge-wire EEDs have been in use almost since the

discovery of energetic materials. An example of a hot bridge-wire EED is depicted in

figure 3.1. Hot bridge-wire devices use a small piece of wire, typically tungsten or

platinum. The EED spot charge is initiated by applying a current pulse to the EED.

The current pulse heats the bridge-wire and initiates the spot charge. The spot charge

is coupled to other energetic materials that make up the EED explosive train. The

output of the spot charge begins the detonation process.

Figure 3.1: Typical hot bridge-wire electro-explosive device construction

The main disadvantage of the hot bridge-wire EED is the sensitive materials used

to form the spot charge. As a result, hot bridge-wire EEDs are sensitive to heat, shock,

radio frequency interference (RFI) and electrostatic discharge (ESD).

Exploding Bridge-wire: In this interesting variation on the hot bridge-wire

concept, the bridge-wire material is heated rapidly enough so a shock wave is created

as the bridge-wire material vaporizes. The shock wave amplitude and velocity is


sufficient to couple it to a relatively insensitive energetic material such as

pentaerythrioltetranitrate (PETN).

Because EBW EED system safety is sufficiently great, they have been used in

fission weapon warheads. Because the wire in the EBW EED initiates the shock wave

in the energetic material, a very specific firing signature is required to cause the EED

to function high order.

Exploding bridge wire based explosive devices are safe but are unsuitable for use

in electronic fuses due to high voltage required for its operation.

Exploding Foil Initiator: The EFI is a miniaturized version of the flying plate

sensitivity test mechanism. The EFI replaces the energetic material used to drive the

flying plate with an electrically initiated exploding metal foil. Figure 3.2 depicts the

typical construction of an EFI. The EFI is a very high speed EED and is constructed

with low inductance electrical connections. The EFI has vastly improved system

safety over that of systems using both hot bridge-wire and EBW EEDs. The EFI is a

signature specific EFI. The EFI can only detonate when coupled to the proper firing

circuit.

Conventional EEDs are susceptible to deterioration or detonation from continuous

low levels of RFI because of gradual heating of the spot charge. However, newer EED

initiation mechanisms provide substantial immunity to RFI susceptibility.

Additionally, because the all-fire pulse is signature specific, firing circuits and system

designs can provide greater operational and safety reliability.

Semiconductor Plasma Initiators: Semiconductor plasma initiators use the heat

transfer characteristics of silicon plasma to initiate energetic materials. These

materials are sensitive to the heat released by the condensing silicon plasma as it

diffuses through the energetic material. Since the energetic material depends on the

plasma temperature and rate of diffusion through the material, the high order function

of a semiconductor initiation mechanism is signature specific.

Semiconductor Junction Ignite: One type of silicon plasma initiator is the

semiconductor junction ignite (SJI). The SJI uses the silicon plasma initiation


mechanism. It provides additional handling and RFI immunity by its unique diode

structure.

Figure 3.2: Exploding foil initiator construction and operation

Electrically, the SJI looks like two schottky diodes connected in series at the

cathodes. To low level signals such as RFI, the schottky diode junctions cannot be

forward biased and act as two capacitors in a series unable to dissipate any power.

However, when the all-fire threshold is exceeded, the schottky diode junctions heat

rapidly generating silicon plasma that can be used to initiate insensitive energetic

materials.

The SJI all-fire threshold can be tailored for amplitude by changing the substrate

background doping and for current by changing the schottky diode area.


Semiconductor Bridge: Another type of silicon plasma initiator is the

Semiconductor Bridge (SCB). The SCB resembles a bow tie of silicon that has been

vapour deposited on a sapphire substrate. The silicon plasma is generated when the

all-fire signal is delivered to the SCB. If the fire pulse is not delivered quickly

enough, the silicon bow tie opens and does not generate plasma providing RFI and

other small signal immunity.

Figure 3.3: Semiconductor bridge initiator

Main needs of igniters, low energy, reliability and safety, was fulfilled by

semiconductor bridges (SCB).SCB uses heavily doped poly-silicon bridge which is

much smaller than conventional bridge-wires. Passage of a current pulse with

significantly less energy than that required for hot-wire ignition produces a plasma

discharge in SCB which ignites the explosive pressed against the bridge, producing an

explosive output within few microseconds.

Production of bridges is routine poly-silicon on-silicon wafer process. The finished

wafers are diced into chips and the chips are placed on a header holding incoming

electrical leads. Aluminium or gold wires are then used to connect the bridge to

header leads. Computer generated masks are used to define the bridge; thus, the SCB

design can be easily tailored for particular application. Because of the intimate

thermal contact of the bridge with underlying substrate excellent no-fire currents are

obtained.


Direct comparisons of the components built with SCBs substituted for bridge-wires

show that the energy for SCB ignition is at least 10 times less than that of bridge-

wires. Further the function times for SCB devices are only few tens of microseconds.

SCB devices have very wide range of applications. They are being used in airbag

ignition, in rock blasting detonators, and in military igniters and detonators. They are

particularly attractive for applications where only very low ignition energy is

available.

They can also be combined with other microelectronic circuits or can be integrated

on chip with peripheral circuitry which can be manufactured using MEMs technology.


CHAPTER 4

FUZE

SCB is integ rated with MEMS based safe, arm and fire (SAF) device. A SAF

Device is employed in military and defence applications particularly used in missiles

for fuzing.

In military munitions, a fuze is the part of the device that initiates function. The

term fuze is used to indicate a ignition device incorporating mechanical and/or

electronic components. A Fuze is a device used in munitions which is designed

to detonate, or to set forces into action to ignite, detonate or deflagrate, the charge (or

primer) under specified conditions. In contrast to a simple pyrotechnic fuse, a

munitions fuze always has some form of safety/arming mechanism, designed to

protect the user from premature or accidental detonation.

The fuze is designed to initiate the warhead either on hitting the target or at some

distance from the target. Today, most missiles and bombs use electronic fuzes. Fuzing

mechanisms are devices used to ‘safe’, ‘arm’ and detonate explosive military

munitions (such as missiles, mines, demolition charges, explosive shells, unguided

bombs and various submunitions). The initiation may also be done after certain time

delay, after the projectile has been fired.

Structure of Fuze

The structure of fuzing mechanism is given in the fig 4.1. The whole circuitry is

consist of three layers. The power supply consists of DC-DC converter with battery,

an analog switch is there used for fast switching and SAF is the safe, arm and fire unit

which do mechanical arming functions. Release buttons are there which are connected

to nose of fuze and can be operated by operator. By pressing these buttons missile will

start functioning. Heating resistances are there which when comes in contact with

propellant can produce hot gases which do arming and ignite the explosive train.

Rather than using these resistances, I will use SCB here because its ignition time is

very low so delay time will be reduced. Also it is highly safe and good immune to

ESD & RF protection. Three switches are there 2 ON-OFF and 1 OFF-ON switch

which are also used in SAF device.


Figure 4.1: Structure of fuze

Types of fuzes

Fuzes are normally divided into two general classes—mechanical and electrical.

These classes only refer to the primary operating principles. They may be subdivided

by their method of functioning or by the action that initiates the explosive train—

impact, mechanical time, proximity, hydrostatic, or long delay.

1. Mechanical Fuzes

In its simplest form, a mechanical fuze is like the hammer and primer used to fire a

rifle or pistol. A mechanical force (in this case, the bomb impacting the target) drives

a striker into a sensitive detonator. The detonator ignites a train of explosives,

eventually firing the main or filler charge. A mechanical bomb fuze is more

complicated than the simple hammer and primer. For safe, effective operation, any

fuze (mechanical or electrical) must have the following design features:


• It must remain safe in stowage, while it is handled in normal movement, and

during loading and downloading evolutions.

• It must remain safe while being carried aboard the aircraft.

• It must remain safe until the bomb is released and is well clear of the delivery

aircraft (arming delay or safe separation period) Depending upon the type of target,

the fuze may be required to delay the detonation of the bomb after impact for a preset

time (functioning delay). Functioning delay may vary from a few milliseconds to

many hours.

• It should not detonate the bomb if the bomb is accidentally released or if the

bomb is jettisoned in a safe condition from the aircraft. To provide these qualities, a

number of design features are used. Most features are common to all types of fuzes.

2. Electrical Fuzes

Electrical fuzes have many characteristics of mechanical fuzes. They differ in fuze

initiation. An electrical impulse is used to initiate the electrical fuze rather than the

mechanical action of arming vane rotation. An electrical pulse from the delivery

aircraft charges capacitors in the fuze as the bomb is released from the aircraft.

Arming and functioning delays are produced by a series of resistor/capacitor networks

in the fuze. The functioning delay is electromechanically initiated, with the necessary

circuits closed by means of shock-sensitive switches. The electric bomb fuze remains

safe until it is energized by the electrical charging system carried in the aircraft.

Because of the interlocks provided in the release equipment, electrical charging can

occur only after the bomb is released from the rack or shackle and has begun its

separation from the aircraft; however, it is still connected electrically to the aircraft's

bomb arming unit. At this time, the fuze receives an energizing charge required for

selection of the desired arming and impact times.

I. Fuze categorization by munition type

The situation of usage and characterstics of the munitions it is intended to activate

the affect fuze design e.g. its safety and actuation mechanism.


1. Artillery Fuzes

Artillery Fuzes are tailored to function in the special circumstances of artillery

projectiles, the relevant factor are the projectile’s initial rapid acceleration, high

velocity and usually rapid rotation, which affect both safety and arming requirements

and options and the target may be moving or stationary.

Artillery Fuzes may be initiated by a timer mechanism, impact or detection of

proximity to the target or a combination of these.

2. Hand grenade fuze

Requirements of hand grenade fuze are defined by the projectile’s small size and

slow delivery over a short distance. This necessitates manual arming before throwing

as the grenade has insufficient initial acceleration for arming to be driven by

"setback" and no rotation to drive arming by centrifugal force.

3. Aerial bomb fuzes

These are also referred to as "pistols". The main design consideration is that the

projectile is large and accelerating vertically downwards and may or may not be

rotating relatively slowly.

4. Landmine fuze

The main design consideration is that the bomb the fuze is intended to actuate is

stationary, and the target itself is moving in making contact.

5. Naval mine fuzes

Relevant design factors are that the mine may be static or moving downward

through the water, and the target is typically moving on or below the water surface,

usually above the mine.

Early artillery time fuzes were nothing more than a hole filled with gunpowder

leading from the surface to the centre of the projectile. The flame from the burning of

the gunpowder propellant ignited this "fuze" on firing, and burned through to the

centre during flight, then igniting or exploding whatever the projectile may have been

filled with.


By the 19th century devices more recognisable as modern artillery "fuzes" were

being made of carefully selected wood and trimmed to burn for a predictable time

after firing. These were still typically fired from smoothbore muzzle-loaders with a

relatively large gap between the shell and barrel, and still relied on flame from the

gunpowder propellant charge escaping past the shell on firing to ignite the wood fuze

and hence initiate the timer.

In the mid-to-late 19th century adjustable metal time fuzes, the fore-runners of

today's time fuzes, containing burning gunpowder as the delay mechanism became

common, in conjunction with the introduction of rifled artillery. Rifled guns

introduced a tight fit between shell and barrel and hence could no longer rely on the

flame from the propellant to initiate the timer. The new metal fuzes typically use the

shock of firing ("setback") and/or the projectiles's rotation to "arm" the fuze and

initiate the timer : hence introducing a safety factor previously absent.

During World War I, mechanical, or clockwork, time fuzes were introduced for

artillery by Germany, and some variants are still in use.

As late as World War I, some countries were still using hand-grenades with simple

black match fuses much like those of modern fireworks: the infantryman lit the fuse

before throwing the grenade and hoped the fuse burned for the several seconds

intended. These were soon superseded in 1915 by the Mills bomb, the first modern

hand grenade with a relatively safe and reliable time fuze initiated by pulling out a

safety pin and releasing an arming handle on throwing.

Modern time often use an electronic delay system.

6. Impact fuzes

Impact, percussion and contact fuzes detonate when their forward motion rapidly

decreases, typically on physically striking an object such as target. The detonation

may be instantaneous and deliberately delayed to occur a present fraction of a second

after penetration of the target. An instantaneous “superquick” fuze will detonate

instantlyon the slight physical contact with the target. A fuze with agraze action will

also detonate on the change of direction caused by slight glancing blow on a physical

obstruction such as the ground.

Impact fuzes in artillery usage may be mounted in the shell nose ("point

detonating") or shell base ("base detonating").


7. Proximity fuzes

Proximity fuzes cause a missile warhead or other munition (e.g. air-dropped bomb

or sea mine) to detonate when it comes within a certain pre-set distance of the target,

or vice versa. Proximity fuzes utilize sensors incorporating one or more combinations

of the following: radar, active sonar, passive

acoustic, infrared, magnetic, photoelectric, seismic or even television cameras. These

may take the form of an anti-handling device designed specifically to kill or severely

injure anyone who tampers with the munition in some way e.g. lifting or tilting it.

Regardless of the sensor used, the pre-set triggering distance is calculated such that

the explosion will occur sufficiently close to the target that it is either destroyed or

severely damaged.

Figure 4.2: Mk 53 Proximity fuze for an artillery shell, circa 1945

8. Remote detonators

Remote detonators use wires or radio waves to remotely command the device

to detonate.

9. Barometric fuzes

Barometric fuzes cause a bomb to detonate at a certain pre-set altitude above sea

level by means of a radar, barometric altimeter or aninfrared rangefinder.


10. Combination fuzes

A fuze assembly may include more than one fuze in series or parallel

arrangements. The RPG-7 usually has an impact (PIBD) fuze in parallel with a 4.5

second time fuze; so detonation occurs on impact, but not later than after 4.5 seconds.

Military weapons containing explosives have fuzing systems including a series

time fuze to ensure that they do not initiate (explode) prematurely within a danger

distance of the munition launch platform. In general, the munition has to travel a

certain distance, wait for a period of time (via clockwork, electronic or even a

chemical delay), or have some form of arming pin/plug removed. Only when these

processes have occurred will the arming process of the series time fuze be complete.

Mines often have a parallel time fuze to detonate and destroy the mine after a pre-

determined period to minimize casualties after the anticipated duration of hostilities.

Detonation of modern naval minesmay require simultaneous detection of a series

arrangement of acoustic, magnetic, and/or pressure sensors to complicate mine-

sweeping efforts.

Fuze safety/arming mechanism

The multiple safety/arming features in the M734 mortar fuze are representative of

the sophistication of modern electronic fuzes.

Figure 4.3: SD2 Butterfly bomb circa 1940 - wings rotate as bomb falls, unscrewing the arming

spindle connected to the fuze


Safety/arming mechanisms can be as simple as the spring-loaded safety levers

on M67 or RGD-5 grenade fuzes, which will not initiate the explosive train so long as

the pin is kept in the grenade, or the safety lever is held down on a pinless grenade.

Alternatively, it can be as complex as the electronic timer-countdown on an

influence sea mine, which gives the vessel laying it sufficient time to move out of the

blast zone before the magnetic or acoustic sensors are fully activated.

In modern artillery shells, most fuzes incorporate several safety features to prevent

a fuze arming before it leaves the gun barrel. These safety features may include

arming on "setback" or by centrifugal force, and often both operating together. Set-

back arming uses theinertia of the accelerating artillery shell to remove a safety

feature as the projectile accelerates from rest to its in-flight speed. Rotational arming

requires that the artillery shell reach a certain rpm before centrifugal forces cause a

safety feature to disengage or move an arming mechanism to its armed position.

Artillery shells are fired through a rifled barrel, which forces them to spin during

flight.

In other cases the bomb, mine or projectile has a fuze that prevents accidental

initiation e.g. stopping the rotation of a small propeller(unless a lanyard pulls out a

pin) so that the striker-pin cannot hit the detonator even if the weapon is dropped on

the ground. These types of fuze operate with aircraft weapons, where the weapon may

have to be jettisoned over friendly territory to allow a damaged aircraft to continue to

fly. The crew can choose to jettison the weapons safe by dropping the devices with

safety pins still attached, or drop them liveby removing the safety pins as the weapons

leave the aircraft.

Aerial bombs and depth charges can be nose and tail fuzed using different

detonator/initiator characteristics so that the crew can choose which effect fuze will

suit target conditions that may not have been known before the flight. The arming

switch is set to one of safe, nose, or tail at the crew's choice.

Base fuzes are also used by artillery and tanks for shells of the 'squash head' type.

Some types of armour piercing shells have also used base fuzes, as have nuclear

artillery shells.

The most sophisticated fuze mechanisms of all are those fitted to nuclear weapons,

and their safety/arming devices are correspondingly complex. In addition

to PAL protection, the fuzing used in nuclear weapons features multiple, highly


sophisticated environmental sensors e.g. sensors requiring highly specific acceleration

and deceleration profiles before the warhead can be fully armed. The intensity and

duration of the acceleration/deceleration must match the environmental conditions

which the bomb/missile warhead would actually experience when dropped or fired.

Furthermore, these events must occur in the correct order.

Note: some fuzes, e.g. those used in air-dropped bombs and landmines may

contain anti-handling devices specifically designed to kill bomb disposal personnel.

The technology to incorporate booby-trap mechanisms in fuzes has existed since at

least 1940 e.g. the German ZUS40 anti-removal bomb fuze.


CHAPTER 5

MEMS Technology

MEMS stands for microelectromechanical systems where different physical

properties of material at micro scale is utilized to electrically control the mechanical

response of a microsystem and vice versa. Electro-thermal, electrostatics,

piezoelectric, piezoresistivity are some of the physical phenomenon adopted by

MEMS technology. They often function as transducers for conversion of energy from

one form to another. For example, application of force on piezoelectric MEMS would

yield electrical current signal. Conversely by applying electric field on a piezoelectric

MEMS world’s smallest motor has been fabricated. Application of heat to a

bimaterial structure can produce mechanical movement due to differential rate of

thermal expansion.

Since in energy scavenging the energy harvested is very small in quantity it is quite

inefficient to use regular size machines and systems for the purpose. To harvest small

amount of energy, small transducers like MEMS can be more beneficial.

To realize a microelectromechanical system with desired response, many obstacles

were overcome in steps that involved studies identifying the problem at hand and

researching for solutions. The challenges involved in design and development of the

MEMS device are listed below:

1. Study of the properties of materials to characterize the

thermomechanical responsivity of the MEMS structure and find optimized

dimension for desired range of responsivity. Develop finite element model and

formulate generalized analytical model to estimate the device response under

given conditions.

2. Find environmental conditions required for thermal actuation of the

MEMS device and continued self-oscillation without any excitation external to

the system or the source. Using finite element modeling and analytical

modeling to estimate the period of oscillation of the MEMS structure and the

magnitude of temperature cycling that occurs in the structure.

3. Characterize pyroelectric capacitors and their power generation

capacity corresponding to temperature cycle frequency. Study


thermomechanical properties of pyroelectric materials for integrating the thin-

film pyroelectric capacitors with the MEMS device. Develop model to

approximate the magnitude and the profile of the power generation from the

combined structure.

4. Design a low power current rectifier and energy storage circuit for

storing the harvested energy from the MEMS structure for powering

subsequent low power mobile or wireless electronics.

With an intention to find an innovative and more efficient way to extract

pyroelectric energy a design of a self-governed temperature cycling system taking

advantage of recent developments in microelectromechanical system is conceived and

design properties and conditions are studied to realize a functional system with

optimized performance for maximum energy conversion efficiency.

5.1 MEMS Devices MEMS stands for microelectromechanical systems. It is an emerging technology

using the microfabrication tools and techniques of integrated circuit manufacturing

industry to fabricate micron scale machines driven by electrical energy. Typically

MEMS technology consists of devices or structures that may or may not have a

moving part but utilizes some mechanical properties and are electronically controlled.

Functional elements of MEMS devices are miniaturized structures that are used as

sensors and actuators. Notable application of MEMS devices are sensors,

micromirrors, microactuators, micropumps, accelerometers, gyroscope, radio

frequency resonators etc.

In functional MEMS devices few basic structures are used to control the

mechanical movement or electrical performances. In microscale the regular

macroscale physics such as gravity, inertia becomes obsolete and other properties

such as stress, thermal capacity or ferroelectricity become more important. In sensors

these properties are utilized to sense pressure, presence of particular gas, light etc. and

to produce electrical signals that are further conditioned by associated

microelectronics to produce useful information. In MEMS actuator similar properties

are utilized to electrically gain control over the mechanical performance of the


structure. Based on which property is utilized, MEMS devices can be electrothermal,

electrostatic, piezoelectric etc. For this study a detail look at electrothermal and

piezoelectric MEMS devices and their behavior is provided in the next sub-sections.

5.2 Electrothermal MEMS

Electrothermal MEMS takes advantage of Joule heating to control the temperature

of the structure and utilizes its thermal properties. In many applications electrothermal

MEMS are used for mechanical movement achieved by thermal expansion due to

controlled heating of the device.

Examples of electrothermal MEMS include micromirrors, microactuators such as

microgrippers, temperature sensors etc.

Often in electrothermal MEMS devices a beam like structure is used that can be

either unimorph or bimorph. In a unimorph structure, the device is made of a single

material of high resistivity usually polysilicon or silicon nitride. The electrical current

flows through the body of the device and generates heat due to resistive loss. Since

the device is in micro scale, the resistance is high and produces enough heat to

thermally expand the device body and cause deformation. Thus thermally caused

deformation is utilized for actuation. In unimorph structures high current has to flow

through the device to raise the temperature high enough to achieve sufficient thermal

expansion to reach the desired level actuation. Very high temperature operation is

involved in this case, and accordingly the device life is reduced.

In a bimorph structure typically more than one type of material is involved. In

similar fashion to unimorph structure, Joule heating is used to increase the

temperature of the device in desired places. Since different materials have different

thermal expansion rates, their expanded length vary and if they are attached to each

other a resultant deflection occurs in an attempt to balance the compressive and

tensile forces experienced by the two materials thermally expanding at differential

rate. In most cases the device involves a cantilever structure that actuates based upon

the temperature increase and the deflection of the cantilever beam.

Electrothermal MEMS are also used as sensors where upon the absorption of heat

the micro structures deform to produce an electrical signal [64]. Since the Joule


heating process is nonreversible, deformation is converted to electrical signal by other

forms of transducers, such as laser reflection or piezoelectric transducers. Because of

its high sensitivity electrothermal MEMS are widely used for infrared imaging .

5.3 Piezoelectric MEMS

MEMS technology benefits itself tremendously by making use of the piezoelectric

properties of material. The property of materials to deform upon application of

electric field is largely used in MEMS technology to actuate micro devices and

structures. Since this process is reversible, piezoelectric property is also utilized in

MEMS based sensors, for example, in pressure sensors.

In microactuators fabricated using piezoelectric materials, electric potential is

applied to deform the device structures in a desirable form to actuate micromotors,

pump microfluidic channels, close microswitches, tune capacitors, adjust micromirror

positions and so on. Application of potential causes polarization in the lattice structure

of the piezoelectric materials that displaces the position of the atoms in the structure

causing deformation. Direction of the deformation is dependent on the piezoelectric

coefficient and the direction of the applied voltage to the material.

Piezoelectric MEMS has also been widely researched and more recently

commercially developed for energy harvesting from pressure and vibrations. In

piezoelectric energy harvesters a MEMS structure is allowed to pick up vibration or

experience pressure which generates electric potential in the material. The generated

potential is typically intermittent and requires conditioning circuit to rectify and store

the harvested energy for use. The piezoelectric conversion efficiency needs to be

higher for energy harvesting application.

Similarly for sensor application the piezoelectric material functions as transducer

to convert pressure to electrical signals [65]. In this case low amplitude of converted

electrical signal is acceptable for the purpose of analysis. Note that in comparison

with electrothermal MEMS that controls the mechanical behavior with electric

current, piezoelectric MEMS control the mechanical response with electric potential.


CHAPTER 6

SYSTEM DEVELOPMENT

The proposed system consists of two parts

Authentication Unit

Delay and Firing Unit

6.1 Authentication Unit –Figure no.6.1 shows the block diagram of the Setter.

The setter consists of LCD, Microcontroller, battery and keypad to enter the password

and arming command. The microcontroller sends commands to the firing unit. The

detonator ID, delay time for arming is fed from the setter which is then set into the

firing unit. The setter is password protected and hence avoids unauthorised access.

The maximum input voltage of the system is 9-12V.

Figure 6.1: Block diagram of Authentication Unit


6.2 Delay and Firing Unit:

The block diagram of Timer or delay unit is as shown in figure 8. The system can

be further divided into two parts as described below.

Figure 6.2: Block Diagram of delay and firing Unit

The Delay and Firing Unit is divided into two parts:

1. ESD & RF protected SCB

2. Circuit for voltage boosting with delay

6.3 Semiconductor Bridge

Semiconductor Bridges (SCBs) are finding increased use as initiators for explosive

and pyrotechnic devices. They offer advantages in reduced voltage and energy

requirements coupled with excellent safety features. SCBs operate in a detonator,

particularly with respect to the interaction of explosive powder and SCB.

Plasma generated from SCBs is used to ignite explosives, where the heavily doped

poly-silicon in contact with power gets melted and evaporated to form high pressure

plasma upon introduction of large currents through the SCB. Because the typical

value of bridge resistance is one ohm, the bridge is ohmic-heated through the


electrical current. The SCB may melt down and eventually evaporate if enough

electrical energy is deposited into the bridge within a limited time.

Once the bridge material is vaporized the applied electric voltage breakes down the

silicon gas generating silicon plasma. This is called as late-time discharge. This

plasma will eventually ignite the explosive material. The SCB works within few

microseconds compared with the milliseconds response of a conventional hot-wire

unit.

A semiconductor bridge comprises a substrate of non-electrically conductive

material, a doped semiconductor layer on the substrate as well as first and second

metal lands forming ohmic contacts on the doped semiconductor layer. An explosive

charge bridges a gap between the metal lands across the doped semiconductor layer.

The lands, gap, semiconductor layer and charge are dimensioned and arranged so that

in response to a current equal to or in excess of a predetermined level having a

duration equal to or in excess of a predetermined value being applied across the gap,

plasma having sufficient energy to energize the explosives is formed in the gap.

6.3.1 Construction

An SCB consists of a small doped polysilicon volume formed on a silicon

substrate. The length of the bridge (100 m) is determined by the spacing of the

aluminium lands seen in the figure. The doped layer is 2 m thick and the bridge is 380

m wide. The lands provide a low ohmic contact to the underlying doped layer. Wires

ultrasonically bonded to the lands permit a current pulse to flow from land to land

through the bridge. The current pulse through the SCB causes it to burst into bright

plasma discharge that heats the exoergic powder pressed against it by a convective

process that is both rapid and efficient. Consequently, SCB devices operate at very

low energies and function very quickly. But despite low energy for ignition, the

substrate provides a reliable heat sink for excellent no-fire levels.


Figure 6.3: Top view and cut view of typical SCB structure

The semiconductor bridge device comprises of following components. An

electrically non-conducting substrate, which may comprise, e.g, sapphire, silicon

dioxide on silicon or silicon nitride on silicon, has an electrically conducting material,

e.g, a semiconductor, which optionally may be a doped semiconductor, mounted

thereon. The electrically conducting material has a temperature coefficient of

electrical resistivity which is negative at a given temperature above about 20oC and

below about 1400oC. the electrically conducting material, which may be selected from

mono crystalline silicon, polycrystalline silicon and amorphous silicon defines a

bridge connecting a pair of spaced-apart pads. The bridge and pads are so

dimensioned and conFIgured that the passage there through of an electrical current of

selected characteristics releases energy at the bridge.

A pair of spaced-apart metallized lands are disposed one on each of the spaced-

apart parts so as to leave at least a portion of the bridge uncovered. Each of the

metallized lands comprises (i) a base layer comprised of titanium and disposed upon

its associated pad, (ii) an intermediate layer comprised of titanium and tungsten and

disposed on its associated base layer, and (iii) a top layer comprised of a tungsten and

disposed on its associated intermediate layer.


Figure 6.4: Top view of SCB

An electrical conductor is connected to each of the metallized lands for passing an

electrical current of the selected characteristics through the bridge. another means of

forming electrically conducting material is in which the semiconductor, of which

bridge and pads are made, to be hybrid material comprised of two materials; the

electrically conducting material being covered by a stratified metal layer, which

preferably covers the entire top surface of the electrically conducting bridge and pads.

A pair of spaced-apart metallized lands are disposed on the stratified metal layer, one

above each of the spaced-apart pads so as to leave at least a portion of the bridge

uncovered. Each of the metallized lands comprise an electrically conductive metal

layer that may be of same material as the third (tungsten) layer on the stratified layer

or of any other suitable electrically conducting material, for example, aluminium.

6.3.2 Fabrication

The semiconductor bridge fabrication technology has been developed at SSPL,

Delhi. The bridge is formed from the heavily doped H shaded region. The doped

region of silicon determines the thickness t and width w of the bridge. In the present

design doped layer is about 2 m thick. The central length of H acts as the filament of

the bridge. Bridge resistance is one ohm. Vapour phase deposition of Aluminium on


the two vertical legs of H defines the length of bridge and also provides ohmic contact

to the device.

Figure 6.5: SCB chip making process

Silicon Bridge is constructed on a silicon substrate by the microelectronics

fabrication technology. The first step is to grow 1 m thick SiO2 on p-type silicon

wafer, by thermal oxidation using first mask. The windows of H shape are opened in

the oxide using photolithographic technique. Diffusion of phosphorous is done

through those windows at 850 degree C. The diffusion time and temperature were

chosen to given an average doping level of atoms/cc and to obtain one ohm resistance

of the bridge.

5x1019 (4.1)

Al metallization was done by vacuum using second mask. The filament was made

of exact size of 100 m x 380 m and 2 m thickness. After scribing and dicing each

semiconductor bridge is tested for required one ohm resistance.


Figure 6.6: Stages of functioning of SCB

4.1.3 SCB Wafer

1.5cm Following figure shows SCB chips made on silicon wafer.

Figure 6.7: SCB chips made on silicon wafer


The intersection of front surface grooves and back surface grooves result in

plurality of square openings formed by intersection of the various grooves, and

provide access between the walls (only one of which is shown in figure) defining

front surface grooves and the walls defining back surface grooves. Respecive portions

of wall comprise the side surfaces of the elements to be cut from wafer substrate.

Cosequently, a flow path is provided as indicated by the unnumbered curved arrows

for the gaseous reactant utilized in gaseous thermal diffusion process to dope front

surface, the walls of front surface grooves, the walls of back surface grooves, and

back surface.

Figure 6.8: Wall formed from grooves

When the thermal diffusion process and other processing steps necessary are

completed, saw cuts are extended through the entire thickness of wafer substrate from

a plurality of dices on which the appropriate SCB circuitry has been formed to

provide a plurality of SCB elements. By usin the illustrated technique, the wafer

substrate maintains its physical integrity and the processing steps may be carried out

on full wafer.

Advantages of SCB

SCB's have following unique features, which make them superior element for

incorporation in new “high tech” electro, initiated explosive devices.

When a fast rising current pulse is applied on the semiconductor

bridge.


SCB's generate hot plasma for ignition of the explosive powder

pressed against the bridge. Ignition is via micro - convective heat transfer

process and not merely a thermal conductive heat transfer as with hot wires.

Ignition energy for SCB's is one tenth to that of conventional bridge-

wires metal foils.

SCB function (i.e. produce a usable explosive output) a thousand

times faster than bridge wires.

By changing the area of bridge one can greatly vary the no fire level

of the device without greatly affecting the all fire energy.

SCB devices are explosively safe. They have high no fire current.

SCBs are highly resistant to ESD pulse.

SCBs being semiconductor should not be compared with metal foils.

SCB cannot fail like metal foils. Current pulse required to function SCB is a

unique signal preventing their accidental operation.

Due to the above unique features SCB's have great benefit for several

application of ignition in pyrotechnic, propellants and explosive devices.

6.4 ESD and RF Protection

SCB is a low energy and small size initiator device with very small firing delay. A

Semiconductor Bridge (SCB) can initiate unintentionally by Electrostatic Discharge

(ESD) and high power RF. The safety of SCB from ESD and RF is of vital

importance. The SCB may fire unintentionally by human handling. There are various

methods implemented to protect the SCB against ESD and RF. The protection of

explosive initiators was done using Zener diode, back to back Zener diodes, TVS

diodes, Schottky diodes etc that were connected along with SCB either by integrating

or as a discrete components. High-level electromagnetic energy produced by Radio

frequency radiation can also induce electrical currents or voltages that may cause

premature activation of Electro-Explosive Devices (EEDs) and electrical arcs that

may ignite flammable materials.

Semiconductor bridge (SCB) initiator is a transducer. Under the effect of high

electrical energy, the power transforms into thermal power. Then the doped

polysilicon layer vaporises and generates high temperature plasma which heats the


explosive. Ultimately, when the temperature reaches ignition temperature, the

explosive detonates.

SCB itself has a good insensitive characteristic against electrostatic inherently.

SCB initiators do not fire under the test conditions of 500pF 5000ohms and 25kV.

6.4.1 ESD Electrostatic Discharge (ESD) interference is a specialized type of ambient

interference that results from the extremely rapid equalization of charges between

conductive surfaces. One common type of ESD is static generated by friction between

two insulating materials. Humans experience ESD as a brief electric shock.

Electronic parts straddling a charged and uncharged plastic surface experience

ESD as a current flow that can be large enough to instantly cause damage or

destruction.

ESD produces heat, light, sound, and electromagnetic radiation throughout the

entire spectrum. A simple ESD spark can set fires, fog film, shock personnel and

ignite explosives. The failure of only one semiconductor junction in an electronic

device can render the device useless. Worse, ESD can cause latent failure so that

components can pass testing, but later fail in field use. Modern military and

commercial electronic devices can have millions of semiconductor junctions. The

effects of ESD are cumulative and progressive degradation that is not readily apparent

can occur over time.

As the representative of modern advanced initiators, SCB initiators have low-firing

energy, short function time and high-reliability. But as a kind of EED, SCB still can

be affected by the electrostatic energy between the pin-to-pin or pin-to-case. The

electrostatic can cause the change of the performance. The pin-to-case electrostatic

mainly generates electrostatic spark and then the spark ignites the explosive to

accidentally ignite initiators or change the electrical explosion property.

Electrostatic is a kind of electric charge in a relatively steady state. When the

objects which have different electrostatic potentials are close to or directly contact

with each other, it can result in charge transfer. Accordingly, we define it as

electrostatic discharge which is expressed as ESD for short. Though the quantity of


static electricity is by no means large, the electrostatic voltage is very high. In

practice, the human body electrostatic voltage can reach several thousand volts or

even tens of thousands of volts.

SCB already possesses better performance of anti-electrostatic. But when coated

with explosive, SCB initiators can be accidentally ignited by ESD to result in serious

harm. The electrostatic affects SCB mainly by Joule heating. When the electrostatic

voltage is less than 25kV, the poly-silicon is heated to melt. Because of the heat

conduction, part of SCB initiators fire or the sensitivity increases. While the

electrostatic voltage exceeds 25kV, the electrostatic energy generates high

temperature on the surface of the bridge and the silicon bridge directly vaporises to

generate plasma. So after ESD, the firing sensitivity of SCB increases and the safety

decreases.

Figure 6.9: Capacitor for ESD protection

Consider the circuit shown in above figure. This represents an SCB, with

resistance R, in parallel with a capacitor C, being driven by a current source, i(t). The

frequency response of this circuit can be determined using steady-state alternating

current (AC) analysis.

At low frequencies, that is w very less than 1/RC, the capacitor impedance is much

greater than R, so the source current flows through the SCB. Conversely, at high

frequencies, that is w very greater than 1/RC, the capacitor impedance is much

smaller than R, so the source current flows through C. Thus, R and C form a low-pass

filter. The design objective, then, is to select C so that it will shunt away the higher

frequency ESD current and pass the lower frequency firing set current. Consequently,

a 1 micro F capacitor was chosen.


The parallel capacitor succeeds in protecting SCB initiators against pin-to-pin ESD

without affecting their performance. The protection circuits have no effect on the

SCB's threshold voltage.

6.4.2 RF Radio-frequency interference or RFI is disturbance that affects an electrical circuit

due to either electromagnetic induction or electromagnetic radiation emitted from an

external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit

the effective performance of the circuit. These effects can range from a simple

degradation of data to a total loss of data. The source may be any object, artificial or

natural, that carries rapidly changing electrical currents, such as an electrical circuit,

the Sun or the Northern Lights.

Due to the suffcient contact between poly-silicon layer and crystalline silicon

substrate, the heat generated on SCB by radio frequency (RF) could be conducted

easily through substrate, which ensures the safety of electro-explosive devices or

initiators under the environmental of static electricity or RF. However, the RF energy

applied to SCB may also cause unintentional firing or characteristics change for

initiators. So the electromagnetic compatibility (EMC) of SCB initiators is more

demanding with increasing levels of electromagnetic interference (EMI) both in

military and civilian applications.

In this project we use transient voltage suppressor (TVS) for RF protection of

SCB. It can withstand high current with wide range suitable breakdown voltages.

The cross-section view of the TVS chip is shown in figure 4.9

Figure 6.10: Cross section view of TVS chip


The equivalent circuit model of SMBJ series TVS chips under direct current (DC)

is shown in figure 4.10. The circuit is open under the condition that the reverse biased

voltage of the TVS is lower than its breakdown voltage. However, when

instantaneous voltage on the chip is higher than its breakdown voltage, the TVS

avalanches and forms an ultra-low-resistance current path. After the instantaneous

pulse, the TVS automatically returns to its high resistance state.

Figure 6.11: Equivalent circuit for back to back connected diodes

TVS chips are in parallel with SCB for electrostatic protection. When the voltage

of SCB after series resistance dividing exceeds the breakdown voltage of TVS chip,

then TVS forms a low-impedance open current path in nanosecond time, and SCB

voltage clamps to a fixed value, so the electrostatic voltage is discharged by TVS chip

to protect SCB from RF.

Breakdown voltage and parasitic resistance of TVS chip are the most important

factors. The lower the breakdown voltage and the lower the parasitic resistance are,

the greater anti-electrostatic capability is.

6.5 Firing Circuit for SCB

Firing circuit is the key component to generate required energy to convert SCB

into plasma state. Firing circuit can be of two types:

1) Capacitor discharge unit;

2) Direct dc firing circuit.


Both circuits are used to produce required all fire current for SCB. Capacitor

discharge unit can be used where voltage supply is high i.e. 24V. Capacitor value in

CDU is so chosen that it can supply required current i.e. 2 Amp and sufficient energy

for functioning delay of the SCB.

6.5.1 Principle of Operation of CDU

CDU unit consist of Capacitor as main storage element of charge, and producing

the required energy for firing of SCB. The firing circuit is illustrated in Figure 4.5,

and the capacitance of ignition capacitor value should be chosen so that it can produce

the required energy with suffcient all fire current. The SCB is connected with switch

2. Consider capacitor is charged with external battery, and switch 2 is closed, then

capacitor will discharge through SCB thereby proving the required energy to SCB,

due to joule heating the SCB will evaporate and within few microseconds the SCB

will converted into plasma state, which causes primary charge for explosive devices.

[14]

Figure 6.11: Capacitor discharge unit for firing of SCB

The firing energy can be calculated based on formula

E=1/(CV2)

Where E is the energy in Joule,

C is the capacitor.

V is the voltage supply.


6.5.2 Firing circuit description

Firing circuit is crucial electronics segment of any explosive initiation system. To

avoid catastrophic situation due to unintended initiation of explosive, firing circuit

should have incorporated all safety measures like ESD protection. Firing circuit

designed by this project ensures the safe and reliable firing of SCB detonator in field

as well as in laboratory. The design includes a p-channel MOSFET as fast operating

switch with few discrete components and a transistor.

Figure 6.12: Firing circuit for SCB

Figure 4.12 dictate the schematic of firing circuit with embedded controller based

delay system. SCB detonator is connected to drain and charging capacitor is

connected to source of p-channel MOSFET, to deliver energy stored in capacitor to

detonator whenever n-channel MOSFET switch get trigger signal from embedded

system. The MOSFET circuit will operate effectively for continuous current up to 5

Ampere and pulsed current of 10 Ampere. To further increase the current rating of

firing circuit more number of MOSFET should be connected in parallel with suitable

heat sink. ESD safety for detonator is included effectively in the circuit by

incorporating zener diode with suitable breakdown voltage; here zener diode is

connected across gate and source of p-channel MOSFET. Zener diode does not allow

the discharging of capacitor until its voltage is more than Zener breakdown voltage.

This prevents initiation of detonator as a result of voltage stored in capacitor due to

ESD effect. Hence firing circuit is prone from ESD effect and effectively suppresses it

with low cost electronic component.


As per required delay period Microcontroller can be configured precisely, once

delay time is over it will send a triggering pulse of logic 1 to n-channel MOSFET.

The current delivered by Microcontroller is enough to drive this MOSFET directly to

activate p-channel MOSFET. Resistor R3 provides the required biasing to n-channel

MOSFET. Trigger pulse switches on n-channel and p-channel MOSFET; intern

delivers energy stored in capacitor to detonator connected across drain of MOSFET.

The instantaneous initiation of detonator takes place while passing energy through it.

Zener diode protects discharge of capacitor until its voltage reaches to Zener

breakdown voltage.

Before implementing embedded firing circuit on to actual hardware, software

simulation has been done using widely accepted electronic simulation environment

called Multisim.

6.6 Booster Circuit

The Booster circuit works on the principle of DC-DC Boost Converter. The key

principle that drives the converter is the tendency of inductor to resist changes in

current by creating and destroying a magnetic field. In a Boost Converter, the output

voltage is always higher than the input voltage. Typically a boost converter consists of

at least two semiconductors and at least one energy storing element. In proposed

design, Energy Reserve Capacitor (ERC) is used to store the boosted voltage.

Tantalum Capacitor is used to lower the leakage current. The available supply voltage

is 6 volts which needs to be boosted for about 30V for trigger.

Figure 6.13: Basic of boost converter

Figure 6.13 illustrates the basic circuit of a Boost converter. However, in this

example the switching transistor is a power MOSFET, both Bipolar power transistors


and MOSFETs are used in power switching, the choice being determined by the

current, voltage, switching speed and cost considerations.

Figure 6.14: Booster circuit during high period of square pulse

Figure 6.14 illustrates the circuit action during the initial high period of the high

frequency square wave applied to the MOSFET gate at start up. During this time

MOSFET conducts, placing a short circuit from the right hand side of L1 to the

negative input supply terminal. Therefore a current ows between the positive and

negative supply terminals through L1, which stores energy in its magnetic field. There

is virtually no current owing in the remainder of the circuit as the combination of D1,

C1 and the load represent a much higher impedance than the path directly through the

heavily conducting MOSFET.

Figure 6.15: Booster circuit during low period of square pulse


Figure 6.15 shows the current path during the low period of the switching square

wave cycle. As the MOSFET is rapidly turned off the sudden drop in current causes

L1 to produce a back e.m.f. in the opposite polarity to the voltage across L1 during

the on period, to keep current owing. This results in two voltages, the supply voltage

VIN and the back e.m.f.(VL) across L1 in series with each other.

This higher voltage (VIN +VL), now that there is no current path through the

MOSFET, forward biases D1. The resulting current through D1 charges up C1 to VIN

+VL minus the small forward voltage drop across D1, and also supplies the load.

Figure 4.16 shows the circuit action during MOSFET on periods after the initial

startup. Each time the MOSFET conducts, the cathode of D1 is more positive than its

anode, due to the charge on C1.

Figure 6.16: Booster circuit during high period after startup

D1 is therefore turned off so the output of the circuit is isolated from the input,

however the load continues to be supplied with VIN +VL from the charge on C1.

Although the charge C1 drains away through the load during this period, C1 is

recharged each time the MOSFET switches off, so maintaining an almost steady

output voltage across the load.


CHAPTER 7

HARDWARE DESCRIPTION

7.1 Circuit diagram of the Authentication Unit

Figure no7.1 shows the authentication unit that contains a power supply unit, a

LCD display unit, a keypad matrix and a communication section. The power supply

unit is a constant 5V supply. It consists of[1] a regulator IC which can take a

maximum of 20V input voltage and in turn produces a 5V constant output voltage.

Figure 7.1: Circuit diagram of setter

The keypad is used to enter the inputs into the system. The various inputs for the

system are detonator ID, delay time and password (optional). Any key pressed will be

sensed by the port 2 pins and the corresponding key pressed will be displayed on the

LCD display. The LCD display connected to the port 0 of the microcontroller is a

16×2 display. It will display the detonator ID, delay time entered by the user.

Whenever the user enters a particular detonator ID through the keypad, the value will

get displayed on the LCD screen. This ID will then be sent to the timer unit via serial


communication and then will get store into the EEPROM memory of the timer

microcontroller. Similarly the entered delay time will also get serially transferred to

the timer part after calculating the necessary count value for that particular delay time.

The crystal connected to the microcontroller provides the necessary frequency for the

operation of the microcontroller.

7.2 Circuit components

Authentication Unit PCB layout

Figure 7.2: PCB layout for setter

Figure7.3: 3D model of setter


1. POWER SUPPLY

A regulated power supply is very much essential for several electronic devices due

to the semiconductor material employed in them have a fixed rate of current as well as

voltage. The device may get damaged if there is any deviation from the fixed rate.

The AC power supply gets converted into constant DC by this circuit. By the help of a

voltage regulator DC, unregulated output will be fixed to a constant voltage.

The circuit is made up of linear voltage regulator 7805 along with capacitors and

resistors with bridge rectifier made up from diodes. From giving an unchanging

voltage supply to building confident that output reaches uninterrupted to the

appliance, the diodes along with capacitors handle elevated efficient signal conveyal.

ICs regulator is mainly used in the circuit to maintain the exact voltage which is

followed by the power supply. A regulator is mainly employed with the capacitor

connected in parallel to the input terminal and the output terminal of the IC regulator.

For the checking of gigantic alterations in the input as well as in the output filter,

capacitors are used. While the bypass capacitors are used to check the small period

spikes on the input and output level. Bypass capacitors are mainly of small values that

are used to bypass the small period pulses straightly into the Earth.

A circuit diagram having regulator IC and all the above discussed components

arrangement revealed in the figure below.

Figure 7.4: Circuit for regulated power supply


Functions of Components

C1: This capacitor is known as bypass capacitor and is employed to bypass

extremely tiny duration spikes to the ground with no distress the other components.

C2: C2 is the filter capacitor employed to steady the slow changes in the voltage

applied at the input of the circuit. Escalating the value of the capacitor amplify the

stabilization as well as the declining value of the capacitor reduces the stabilization.

Moreover this capacitor is not alone capable to ensure very constricted period spikes

emerge at the input.

C3: C3 is known as a filter capacitor employed in the circuit to steady the slow

alterations in the output voltage. Raising the value of the capacitor enlarges the

stabilization furthermore declining the value of the capacitor declined the

stabilization. Moreover this capacitor is not alone capable to ensure very fine duration

spikes happen at the output.

C4: C4 is known as bypass capacitor and worked to bypass very small period

spikes to the earth with no influence the other components.

U1: U1 is the IC with positive DC and it upholds the output voltage steady exactly

at a constant value even although there are major deviation in the input voltage.

IC 7805 is a DC regulated IC of 5V. This IC is very flexible and is widely

employed in all types of circuit like a voltage regulator. It is a three terminal device

and mainly called input , output and ground. Pin diagram of the IC 7805 is shown in

the diagram below.


Figure 7.5: Pin diagram of 7805

PIN DESCRIPTION

1. INPUT: In this pin of the IC positive unregulated voltage is given in

regulation.

2. GROUND: In this pin where the ground is given. This pin is neutral

for equally the input and output.

3. OUTPUT: The output of the regulated 5V volt is taken out at this pin

of the IC regulator.

The output generated from the unregulated DC output is susceptible to the

fluctuations of the input signal. IC voltage regulator is connected with bridge rectifier

in series so to steady the DC output against the variations in the input DC voltage. To

obtain a stable output of 5V, IC 7805 is attached with 6-0-6V along with 500mA step

down transformer as well as with rectifier. To suppress the oscillation which might

generate in the regulator IC, C2 capacitor of 0.1 uF value is used. When the power

supply filter is far away from the regulated IC capacitor C2 is used. Ripple rejection

in the regulator is been improved by C4 capacitor by avoiding the ripple voltage to be

amplified at the regulator output. The output voltage is strengthen and deduction of

the output voltage is done capacitor C3. To avoid the chance of the input get shorted

D5 diode is used to save the regulator. If D5 is not presented in the circuit, the output


capacitor can leave its charge immediately during low impedance course inside the

regulators.

2. ATmega 16: ATmega 16 microcontroller DIP(40 pin) is used for the

authentication unit. The ATmega16 is a low-power CMOS 8-bit microcontroller

based on the AVR enhanced RISC architecture. By executing powerful instructions in

a single clock cycle, the ATmega16 achieves throughputs approaching 1 MIPS per

MHz allowing the system designer to optimize power consumption versus processing

speed.

Features

• High-performance, Low-power Atmel® AVR® 8-bit Microcontroller

• Advanced RISC Architecture

– 131 Powerful Instructions – Most Single-clock Cycle Execution

– 32 x 8 General Purpose Working Registers

– Fully Static Operation

– Up to 16 MIPS Throughput at 16 MHz

– On-chip 2-cycle Multiplier

• High Endurance Non-volatile Memory segments

– 16 Kbytes of In-System Self-programmable Flash program memory

– 512 Bytes EEPROM

– 1 Kbyte Internal SRAM

– Write/Erase Cycles: 10,000 Flash/100,000 EEPROM

– Data retention: 20 years at 85°C/100 years at 25°C(1)

– Optional Boot Code Section with Independent Lock Bits

In-System Programming by On-chip Boot Program

True Read-While-Write Operation

– Programming Lock for Software Security

• JTAG (IEEE std. 1149.1 Compliant) Interface

– Boundary-scan Capabilities According to the JTAG Standard

– Extensive On-chip Debug Support

– Programming of Flash, EEPROM, Fuses, and Lock Bits through the JTAG

Interface

• Peripheral Features


– Two 8-bit Timer/Counters with Separate Prescalers and Compare Modes

– One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture

Mode

– Real Time Counter with Separate Oscillator

– Four PWM Channels

– 8-channel, 10-bit ADC

8 Single-ended Channels

7 Differential Channels in TQFP Package Only

2 Differential Channels with Programmable Gain at 1x, 10x, or 200x

– Byte-oriented Two-wire Serial Interface

– Programmable Serial USART

– Master/Slave SPI Serial Interface

– Programmable Watchdog Timer with Separate On-chip Oscillator

– On-chip Analog Comparator

• Special Microcontroller Features

– Power-on Reset and Programmable Brown-out Detection

– Internal Calibrated RC Oscillator

– External and Internal Interrupt Sources

– Six Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down,

Standby and Extended Standby

• I/O and Packages

– 32 Programmable I/O Lines

– 40-pin PDIP, 44-lead TQFP, and 44-pad QFN/MLF

• Operating Voltages

– 2.7V - 5.5V for ATmega16L

– 4.5V - 5.5V for ATmega16

• Speed Grades

– 0 - 8 MHz for ATmega16L

– 0 - 16 MHz for ATmega16

• Power Consumption @ 1 MHz, 3V, and 25°C for ATmega16L

– Active: 1.1 mA

– Idle Mode: 0.35 mA

– Power-down Mode: < 1 µA


Pin Configuration

Pin Descriptions

VCC: Digital supply voltage.

GND: Ground.

Port A (PA7..PA0): Port A serves as the analog inputs to the A/D Converter.

Port A also serves as an 8-bit bi-directional I/O port, if the A/D Converter is not

used. Port pins can provide internal pull-up resistors (selected for each bit). The

Port A output buffers have symmetrical drive characteristics with both high sink

and source capability. When pins PA0 to PA7 are used as inputs and are externally

pulled low, they will source current if the internal pull-up resistors are activated.

The Port A pins are tri-stated when a reset condition becomes active, even if the

clock is not running.

Port B (PB7..PB0): Port B is an 8-bit bi-directional I/O port with internal pull-

up resistors (selected for each bit). The Port B output buffers have symmetrical

drive characteristics with both high sink and source capability. As inputs, Port B

pins that are externally pulled low will source current if the pull-up resistors are

activated. The Port B pins are tri-stated when a reset condition becomes active,

even if the clock is not running. Port B also serves the functions of various special

features of the ATmega16.


Port C (PC7..PC0): Port C is an 8-bit bi-directional I/O port with internal pull-

up resistors (selected for each bit). The Port C output buffers have symmetrical

drive characteristics with both high sink and source capability. As inputs, Port C


activated. The Port C pins are tri-stated when a reset condition becomes active,

even if the clock is not running. If the JTAG interface is enabled, the pull-up

resistors on pins PC5(TDI), PC3(TMS) and PC2(TCK) will be activated even if a

reset occurs. Port C also serves the functions of the JTAG interface and other

special features of the ATmega16.

Port D (PD7..PD0): Port D is an 8-bit bi-directional I/O port with internal pull-

up resistors (selected for each bit). The Port D output buffers have symmetrical

drive characteristics with both high sink and source capability. As inputs, Port D


activated. The Port D pins are tri-stated when a reset condition becomes active,

even if the clock is not running. Port D also serves the functions of various special

features of the ATmega16.

RESET: Reset Input. A low level on this pin for longer than the minimum

pulse length will generate a reset, even if the clock is not running. The minimum

pulse length is given in Table 15 on page 38. Shorter pulses are not guaranteed to

generate a reset.

XTAL1: Input to the inverting Oscillator amplifier and input to the internal

clock operating circuit

XTAL2: Output from the inverting Oscillator amplifier.

AVCC: AVCC is the supply voltage pin for Port A and the A/D Converter. It

should be externally connected to VCC, even if the ADC is not used. If the ADC is

used, it should be connected to VCC through a low-pass filter.

AREF: AREF is the analog reference pin for the A/D Converter.

3. Keypad:

The keypad has 16 keys in a 4*4 matrix form. The keys are used to enter the

password , det. ID and then to feed the delay time. The delay will be entered as 2-digit

number.


4. LCD Display

It enables the system to talk with the user. The LDC display used here is a 16

character 2-line LCD module. It displays all the functions which are to be

programmed.

7.3. Delay and Firing Circuit

The circuitry for fuzing mechanism is as shown in fig 5. It consists of three layers:

Electronic circuitry, Si-based safe initiator and mechanical arming unit.

The whole system is consists of following components:

Figure 7.6: Schematic diagram for Fuzing

Working of Delay and Firing Unit

A 3V supply is given to the microcontroller and to the inductor. Current will pass

through inductor and creates the magnetic field across inductor due to this a constant

voltage across inductor will occur and pwm switching is done through microcontroller

to on and off the switch. The voltage will continuously increases and charge the

output capacitor. Then we get boosted voltage from 3V to 30V.

On the launch of system a setback force comes then accelerometer senses that

force and gives signal to the microcontroller it waits for 2 seconds if microcontroller

again senses that forces then it gives trigger signal to the arming mosfet and then


switch will on. Current will flow through SCB, plasma created and comes in contact

with gas generator pyrotechnic material then it creates a pressure of about 6×105 Pa

and screen will move from safe to arm position. Then after a delay of 4 seconds firing

pulse will go firing switch will on. Current will flow through firing SCB, plasma

created and comes in contact with explosive material and then explosion will be done.

Layer1 schematic

Figure 7.7: Layer1 circuitry

7.3 PCB Layout


Figure 7.8: Layer1 Top View

Figure 7.9: Layer 1 Bottom view


1.) 3D models of Layer 1

Figure 7.10: Layer 1 3D Top view

Figure 7.11: Layer 2 3D Bottom view

Layer 2 schematic


Figure 7.12: Layer 2 schematic

1.) PCB Layout of layer 2

Figure 7.13: Layer 2 Top view


Figure 7.14: Layer 2 Bottom view (use SCB instead of R1, R2 with TVS diode)

1. POWER SUPPLY UNIT

We give 3V supply through a Li-ion battery connected with 0.1µf capacitor. Then

it is connected to the inductor of 10 mH. A MOSFET of 2N7002CK is connected to

the 8-pin microcontroller which increases switching speed of MOSFET the power is

boosted from 3V to 30V.

2. ATtiny85

The purpose of using the 8-pin microcontroller is to achieve miniaturization. Atmel

tinyAVR® devices are optimized for applications that require performance, power

efficiency, and ease-of-use in a small package. Alf (Egil Bogen) and Vegard

(Wollan)'s RISC processor. The use of "AVR" generally refers to the 8-bit RISC line

of Atmel AVR Microcontrollers. The AVR is a modified Harvard architecture

machine where program and data are stored in separate physical memory systems that

appear in different address spaces, but having the ability to read data items from

program memory using special instructions.

All tinyAVR devices are based on the same architecture and compatible with other

AVR devices. Integrated ADC, EEPROM memory and brown-out detector we can


build applications without adding external components. TinyAVR offers flash

memory and on-chip debug for fast, secure, cost-effective in-circuit upgrades that

significantly cuts in time to market.

The devices are supported by the Atmel Studio development platform. It enables

code development in C or Assembly, provides cycle-accurate simulation, and

integrates seamlessly with starter kits, programmers, debuggers, evaluation kits, and

reference designs. This results in faster development, a more-production development

team, and rapid time-to-market.

The tinyAVR offers an unrivalled combination of miniaturization, processing

power, analog performance, and system-level integration. The tinyAVR is the most

compact, feature-rich device in the AVR family—and the only device capable of

operating at just 0.7V.

7.2.1 Key Features of the Atmel AVR family

1. High Performance, Low Power AVR® 8-Bit Microcontroller

2. Advanced RISC Architecture

– 120 Powerful Instructions – Most Single Clock Cycle Execution

– 32 x 8 General Purpose Working Registers

– Fully Static Operation

3. Non-volatile Program and Data Memories

– 2/4/8K Bytes of In-System Programmable Program Memory Flash

4. Endurance: 10,000 Write/Erase Cycles

– 128/256/512 Bytes In-System Programmable EEPROM

5. Endurance: 100,000 Write/Erase Cycles

– 128/256/512 Bytes Internal SRAM

– Programming Lock for Self-Programming Flash Program and EEPROM Data

Security

6.Peripheral Features

– 8-bit Timer/Counter with Prescaler and Two PWM Channels

– 8-bit High Speed Timer/Counter with Separate Prescaler

7. 2 High Frequency PWM Outputs with Separate Output Compare Registers

8. Programmable Dead Time Generator


– USI – Universal Serial Interface with Start Condition Detector

– 10-bit ADC

9. 4 Single Ended Channels

10. 2 Differential ADC Channel Pairs with Programmable Gain (1x, 20x)

11. Temperature Measurement: Programmable Watchdog Timer with Separate

On- chip Oscillator & On-chip Analog Comparator.

12. Special Microcontroller Features: debug WIRE On-chip Debug System, In-

System Programmable via SPI Port, External and Internal Interrupt Sources, Low

Power Idle, ADC Noise Reduction, and Power-down Modes. Enhanced Power-on

Reset Circuit, Programmable Brown-out Detection Circuit & Internal Calibrated

Oscillator.

13. I/O and Packages

– Six Programmable I/O Lines

– 8-pin PDIP, 8-pin SOIC, 20-pad QFN/MLF, and 8-pin TSSOP (only

ATtiny45/V)

14. Operating Voltage

– 1.8 - 5.5V for ATtiny25V/45V/85V

– 2.7 - 5.5V for ATtiny25/45/85

15. Speed Grade

– ATtiny25V/45V/85V: 0 – 4 MHz @ 1.8 - 5.5V, 0 - 10 MHz @ 2.7 - 5.5V

– ATtiny25/45/85: 0 – 10 MHz @ 2.7 - 5.5V, 0 - 20 MHz @ 4.5 - 5.5V

16. Industrial Temperature Range

17. Low Power Consumption

– Active Mode: 1 MHz, 1.8V: 300 μA

– Power-down Mode: 0.1 μA at 1.8V

Pin configuration of ATtiny85 microcontroller

Figure 7.15: Pin configuration of ATTINY85


Pin Description

1. VCC: Supply voltage.

2. GND: Ground.

3. Port B (PB5..PB0): Port B is a 6-bit bi-directional I/O port with internal pull-

up resistors (selected for each bit). The Port B output buffers have symmetrical

drive characteristics with both high sink and source capability. As inputs, Port B


activated. The Port B pins are tri-stated when a reset condition becomes active,

even if the clock is not running.

4. RESET: Reset input. A low level on this pin for longer than the

minimum pulse length will generate a reset, even if the clock is not running

and provided the reset pin has not been disabled. The reset pin can also be

used as a (weak) I/O pin.

Accelerometer

The ADXL210 are low cost, low power, complete 2-axis accelerometers with a

measurement range of either ±10 g. The ADXL210 can measure both dynamic

acceleration (e.g., vibration) and static acceleration (e.g., gravity).


Figure 7.16: Functional Block Diagram of ADXL210AQC

The outputs are digital signals whose duty cycles (ratio of pulse width to period)

are proportional to the acceleration in each of the 2 sensitive axes. These outputs may

be measured directly with a microprocessor counter, requiring no A/D converter or

glue logic. The output period is adjustable from 0.5 ms to 10 ms via a single resistor

(RSET). If a voltage output is desired, a voltage output proportional to acceleration is

available from the XFILT and YFILT pins, or may be reconstructed by filtering the duty

cycle outputs.

The bandwidth of the ADXL202/ADXL210 may be set from 0.01 Hz to 5 kHz via

capacitors CX and CY. The typical noise floor is 500 µg/kHz allowing signals below

5 mg to be resolved for bandwidths below 60 Hz.The ADXL210 is available in a

hermetic 14-lead Surface Mount CERPAK, specified over the 0oC to +70oC

commercial or –40oC to +85oC industrial temperature range.

Features of accelerometer ADXL210AQC are as follows:

2-Axis Acceleration Sensor on a Single IC Chip

Measures Static Acceleration as Well as Dynamic Acceleration

Duty Cycle Output with User Adjustable Period


Low Power <0.6 mA

Faster Response than Electrolytic, Mercury or Thermal

Tilt Sensors

Bandwidth Adjustment with a Single Capacitor Per Axis

5 mg Resolution at 60 Hz Bandwidth

+3 V to +5.25 V Single Supply Operation

1000 g Shock Survival

APPLICATIONS

2-Axis Tilt Sensing

Computer Peripherals

Inertial Navigation

Seismic Monitoring

Vehicle Security Systems

Battery Powered Motion Sensing


CHAPTER 8

Safe, Arm & Fire Device

8.1 Architecture and Principle of Operation of the SAF Device

As illustrated in Fig. 2, the architecture of the SAF MEMS device consists in an

assembly of different wafers.

Fig. 8.1: View of the MEMS SAF device made of three stacked parts

The bottom layer of Fig. 2 constitutes the mechanical arming function. The

intermediary layer is a silicon chip, called Si-based safe initiator, on which are

integrated 2 electrical resistances (one to initiate an explosive and one for the

pyrotechnical actuator) and microswitches to realize the electrical arming and

disarming functions. The top layer, thicker one, is the electronic circuitry and power


supply integrating if required one super capacity. To prevent that a shock unlocks the

mechanical screen, an inertial pin can be inserted into the device to block the screen.

The SAF device operations procedure is illustrated in Fig. 8.2.

Figure 8.2: Operations procedure of the MEMS SAF device (a) in safe mode, (b) mechanically

armed, (c) electrically armed and (d) secondary explosive initiation by initiator

The MEMS SAF is stored in safe mode: the screen is locked and the initiator pads

are both connected to the electrical ground (Fig. 3a). The first order is for the

mechanical arming (Fig. 3b): the inertial pin is removed by the acceleration; then the

microcontroller sends an electrical order to the microactuator resistance. The gas

generated by the pyrotechnical actuator moves the screen in armed position. Then, the

SAF is electrically armed, that is to say the microinitiator electrical short-circuit to

electrical ground is cut (Fig. 3c). At this stage, if the operator does not send an order

to stop the procedure, the microcontroller sends an electrical order to the initiator to


ignite the primary explosive located in its cavity (Fig. 3d), and the secondary

explosive can be initiated. If there is a failure during the sequences, it is possible to

disconnect definitively the microinitiator from its power supply by breaking its

electrical connections.

The geometry and dimensions of actuator cavity and propellant volume used for

modelling is as shown below in fig 10(a),10(b):

Figure 8.3 (a): Microactuator cavity before the gases are released

Figure 8.3(b): Microactuator cavity after the gases are released

First, the pyrotechnical actuator which contains 0.1mm3 of bi-metallic energetic

material [6] is simulated using Matlab/Simulink to predict the pressure and

temperature increase in the cavity that pushes the screen. As shown in the Fig. 18,

after the energetic material ignition, the pressure increases rapidly and reaches

6.43.105Pa when the screen is blocked in its final position. The maximal temperature

is about 100°C. For this simulation, we assume that there is no gas leakage.


Figure 8.4: Pressure evolution in the micro actuator cavity and slide containing the screen

8.2. DESIGN OF MECHANICAL ARMING FUNCTION

The bottom layer of Fig. 2 describes the mechanical arming function. It constitutes

an arming function case with base and its cover, a movable mechanical screen and an

inertial pin.

8.2.1 Base

Base forms the bottom part of the mechanical arming function. It has a step in

periphery of the cavity so that the cap can be firmly placed over it. The Pro-E model

of Base of mechanical arming function is shown in fig.4. A detailed along with its

dimensions is shown in fig. 5. It has two through holes in its cavity, one for the

inertial pin and another as a passage for charge to initiate the secondary explosives

after primary explosion takes place.


Fig.8.5: Pro-E model of Base


Fig.8.6: Base


8.2.2 Cover

Cover forms the top part or cap of the mechanical arming function. It has the

complementary print as a crenel shape to that of base so that it can be placed over

the base. The Pro-E model of Cover of mechanical arming function is shown in

fig. 6. The Cover of mechanical arming function along with its dimensions is

shown in fig.7. It also contains two through holes, one for the actuation of the

microinitiator and another for the passage for charge to initiate the secondary

explosives after primary explosion takes place.

Figure 8.7: Pro-E model of Cover


Figure 8.8: Cover

8.2.3 Mechanical Screen

Mechanical screen of the SAF device interrupts the explosive train to keep the

detonator safe and to arm it by mechanically moving from the safe position. It is


placed in the cavity formed in Base of mechanical arming function. The Pro-E model

of Mechanical Screen of mechanical arming function is shown in fig.8. The

Mechanical Screen along with its dimensions can be seen in fig. 9. The corner radius

of curvature is slightly larger than the one of the slide corners in which it moves. It is

thus able to achieve its end of course in force in the slider and to remain thus blocked

in armed position. It too has a through hole for the inertial pin which keeps the screen

in safe position.

Figure 8.9: Pro-E model of Mechanical Screen


Figure 8.10: Mechanical Screen


8.2.4 Inertial Pin

To prevent that a shock unlocks the mechanical screen, an inertial pin is inserted

into the device to block the screen and keep it in safe position. The Pro-E model of

Inertial Pin is shown in fig.10 and detailed design is as shown in fig.11. It consists of

a circular cylinder to which attached is the spring that keeps the inertial pin to lock the

mechanical screen and be in safe condition.

Fig. 10: Pro-E model of Mechanical Screen


Fig. 11: Inertial Pin


8.2.5 Assembly An Assembly of the Mechanical Arming is shown in fig.12 with Base containing

the Mechanical Screen in safe position. Inertial pin blocking the screen from

unintended arming and cover forms the covering of the assembly.

Fig. 12a: Pro-E model of Assembly

Fig. 12b: Pro-E model of Disassembly


Fig. 13: Mechanical Arming Assembly


CHAPTER 9

FLOW CHART


CHAPTER 10

SIMULATION RESULTS

The Authentication and the firing circuit are simulated in PROTEUS7.7. Before

implementing setter on to actual hardware, software simulation has been done using

widely accepted electronic simulation software PROTEUS7.7.

Figure 10.1 shows the image of simulation, it is apparent from image that inputs

are entered by the user and delay and firing command are sent to the firing circuit

through serial communication. User needs to first enter the password for the system

which will avoid unauthorized usage. If correct password is entered by the user then

detonator ID and the desired delay has to be entered.

Figure 10.1: Simulation of Authentication unit


Figure 10.2: Simulation for Delay and Firing Unit

Then the user is asked whether to give firing command or to abort. If user wants to

abort then the main menu will be displayed again and the system password has to be

entered again.

This circuit is the vital part of the design which makes the circuit 3V operated. In

this circuit a 3V battery voltage is boosted by the boost convertor to 30V. Then trigger

pulse is given to switch to discharge CDU. CDU discharges through SCB. In this

design the leakage of capacitor should be ultra low. For low leakage current tantalum

capacitor is used.

Firstly, arming pulse is given to on switch, then capacitor will discharge through

SCB and after a delay of 4 sec it gives firing pulse to on 2nd switch. With this fire

pulse, SCB is ignited then explosive will be done. This circuit is operated at 3V Li-ion

battery which has 240mAh capacity. Typically a CR2032 coin cell is used. The

supply voltage is 3V.


Capacitor discharge profile shown in figure 10.3. Relevant resistor values are

used for proper biasing and amplification in simulation model. The discharge profile

has significance that it will be directly applied to detonator for initiation.

Figure10.3: Capacitor discharge profile

Figure10.4: PWM waveform


Relevant values for the capacitor, inductor and the duty cycle for PWM are taken

for the boost convertor circuit. The duty cycle for the PWM of the microcontroller

used in the firing circuit is 92% to obtain the boosted voltage of 30volts. PWM is used

for switching the MOSFET of the boost convertor circuit.


CHAPTER 11

SUMMARY &CONCLUSION

The MEMS SAF device previously designed used 20-pin microcontroller so it took

more space. As, today is the age of miniaturization we obtain it by using an ATtiny10

6-pin microcontroller. Hence, it fulfills the requirement of compactness, reliability

and speed. By using SCB instead of resistances we get our system more compact, safe

with fast ignition time.

SCB provides safe, reliable and low energy means of initiators. For explosive

detonations SCBs are best suited. Voltage booster circuit boosts the input voltage to

about 30V. The firing circuit of SCB designed in this project produces a high current

pulse for sufficient time required for plasma generation. The design can be made with

discrete as well as integrated components.

The integrated chip needed to be developed using mixed signal VLSI technology.

It has various units which were simulated and the results are acceptable for proper

functioning of SCB chip. It can have more units such as reset unit or power

managemant unit or logic unit that has higher functionality as per requirement. The

resulting chip will be compact in size and will have maximized functionality.

Based on specifications, schematic and PCB layout is made in Diptrace freeware

2.4.0.2 software, simulation is done in Proteous 7.7 and modelling is done in the Pro-

E 5.0. 2D drawings of mechanical arming parts of SAF layer are drawn. Designs are

prepared for the same.

11.1 Future Scope

The future scope of system is to make the system wireless. This can be done by

transferring wireless power transfer also wireless data transfer. This can be done

through inductive wireless power and data transfer and also capacitive wireless power

and data transfer. There are also many ways to transfer wireless power and data

transfer.


11.2 Applications

Integrated pyro SCB chip is used in:

Military

Defence


LIST OF PUBLICATIONS

1) Paper presented in First International Conference on Emerging Trends in

Electronics and Communication Engineering(ETECE-2015) Organized by

Department of Electronics & Telecommunication, Bharatiya Vidyapeeth Deemed

University College of Engineering, Pune-43 on 2-3 April 2015.

Paper Title "Pyro MEMS Design for Fuze", Pooja Sharma1, Dr. Virendra Kumar2,

Archana Singh3 ,1&3 G. S. Moze COE Balewadi, Pune, Savitribai Phule Pune

University, Pune , 2 ARDE-DRDO Pashan, Pune.

2) Paper published in International Journal of Electrical, Electronics and Data

communication, ISSN(Online):2321-2950, ISSN(Print):2320-2084, Special issue-1,

April 2015.

Paper Title "Pyro MEMS Design for Fuze", Pooja Sharma1, Dr. Virendra Kumar2,

Archana Singh3 ,1&3 G. S. Moze COE Balewadi, Pune, Savitribai Phule Pune

University, Pune , 2 ARDE-DRDO Pashan, Pune.


REFERENCES 1. L. E. Hollander, Jr., “Semiconductor Transducers”, US. Patent 3,392.576, Jul

16, 1968.

2. Robert W. Bikes Jr.; Alfred C. Schwarz. “Semi-Conductor Bridge (SCB)

Igniter”, US. Patent 4,708,060, November 24, 1987.

3. Robert L. Pro_t, John L. Wells, Alan L. Lause, John C. Cole, “Thin Film bridge

initiator and method therfor”, US Patent 4,729,315, Mar 8, 1988.

4. Eldon Nerheim, “Integrated silicon plasma switch”, US Patent 4,840,122, June

20, 1989.

5. David A. Benson, Robert BickesJr, Robert S. Blewer, “Tungsten bridge for low

energy ignition of explosive and energetic materials”, US Patent 4,976.200, dec 11,

1990.

6. Thomas A. Baginski, “Method of forming radio frequency and electrostatic

discharge insensitive electro-explosive devices” Patent No.US 6272965 B1.

7. Bernardo Martinez-Tovar, John A. Montoya, “Surface connectable

semiconductor bridge elements, devices and methods”, Patent No. EP 0948812 B1, 2

Mar 2005.

8. J. Keith Hartman; Carroll B. “Zener diode for protection of integrated circuit

explosive bridge” Patent Number: 5,309,841, May 10, 1994.

9. Avery, “Protective integrated circuit device utilizing back-to-back Zener

diodes”, Patent Number :US 4405933 A. 20 Sep 1983.

10. Tony L. King and William W. Tarbell, “Pin-to-pin Electrostatic Discharge

Protection for Semiconductor Bridges”, Sandia National Laboratories, 2002.

11. Thomas A. Baginski, Keith A, Thomas “A RF-Insensitive Electroexplosive

Device with 500 V standoff capability”,Members, IEEE.

12. Vivian E. Patz; Stafford A. Smithies “Detonator Firing Element” Patent

Number: 4,819,560, April 11, 1989.

13. Robert W. Bickes, Jr. and David E. Wackerbarth “Semiconductor Bridge, SCB,

Ignition Studies of AI/CuOThermitet”, Western State Section of the Combustion

Institute 1997 Spring Meeting.

14. R. W. Bickes, Jr. “Explosive systems Utilizing semiconductor bridge, SCB,

Technology”, Explosive Components Department, Sandia National Laboratories.


15. Aviv Ronen; YairBaruchi; EranZvulun, “Energetic unit based on

semiconductor bridge” Patent Number: WO 2012/176198, December 27, 2012.

16. Sanjeev Sharma, Sushil Kumar, “Simulation Model of Boost Converter used in

Photovoltaic System”, EN Deptt.,KIET,Ghaziabad, International Journal of Advances

in Electrical and Electronics Engineering.

17. B. M. Hasaneen, Adel Mohammed, “Design and simulation of DC/DC Boost

Converter”, IEEE, Power Systems Conference, 2008.

18. S. Masri, P. W. Chan, “Design and development of DC-DC boost converter

with constant output voltage”, IEEE, ICIAS, 2010.

19. Pezous H., Rossi C., Sanchez M., Mathieu F., Dollat X., Charlot S., Salvagnac

L., Conedera V., Integration of MEMS based safe arm and fire device, Sensors and

Actuators A 159 (2010) 157–167

20. Pezous H., Sanchez M., Mathieu F., Dollat X., Charlot S., Rossi C.,

Fabrication, Assembly and Tests of a MEMS based Safe, Arm and Fire Device,

Proceedings of PowerMEMS 2008+ microEMS2008, Sendai, Japan, November 9-12,

(2008)

21. Rossi C., Esteve D. , Micropyrotechnics, a new technology for making

energetic microsystems: review and prospective, Sensors and Actuators A 120 (2005)

297–310

22. Robinson C. H., Hoang T. Q., Gelak M. R., Smith G. L., Wood R. H.,

Materials, Fabrication and Assembly Technologies for Advanced MEMS Based

Safety and Arming Mechanisms for Projectile Munitions.

23. Patent No.: US 8,276,515 B1 (United States), May 1’ 2009, Ultra-Miniature

Electro-Mechanical Safety and Arming Device, Oct. 2, 2012

24. Verma V.K., Kokate V. K., Nandgavc P., Design of MEMS Electronic Safety

and Arming Mechanism for Projectile Munition,

25. Liqun D.U., Shengfang J, Weirong N., Qijia W, Fabrication of Fuze Micro-

electro-mechanical System Safety Device,

26. Patent No.: US 8,640,620 B1 (United States), March 5’ 2012, Non-Inertial

Safe And Arm Device, 2014

27. Patent No.: US 6,295,932 B1 (United States), March 15’ 1999, Electronic Safe

Arm And Fire Device, 2001


28. Patent No.: US 6,431,071 B1 (United States), Sept 18’ 2000, MEMS Arm Fire

And Safe And Arm Devices.2002

29. Zhang K.L., Choua S.K., Ang S.S., Tang X.S., A MEMS-based solid

propellant microthruster with Au/Ti igniter, Sensors and Actuators A 122 (2005) 113–

123

30. Stewart D.S., Miniaturization Of Explosive Technology And Microdetonics,

Mechanics of 21st Century - ICTAM04

31. Rossi C., Briand D., Dumonteuil M., Camps T., Pham P.Q., Rooij N.F.,

Matrix of 10×10 addressed solid propellant microthrusters: Review of the

technologies, Sensors and Actuators A Physical 126, issue 1, 241-252, 2006

32. Rossi C., Zhang K., Estève D., Alphonse P., Tailhades P., Vahlas C.,

Nanoenergetic Materials for MEMS: A Review, Journal of Microelectromechanical

Systems, Vol. 16, No. 4, August 2007


APPENDIX I

Component List for Authentication Unit

The following components are used for the setter circuit.

1) Atmega 16 microcontroller DIP(40 pin)

2) 4*4 matrix Keypad

3) LCD(16*2) Display

4) Diode 1N4007 four diodes are used to form the rectifier.

5) Capacitors 1000uF,470 uF ceramic capacitors and two capacitors of 22pF are

used.

6) Crystal of 8MHz is used.

7) Resistor 270 ohms.

8) Male and female berg strips (40*1).

9) 8 pin male and female relimate connectors.

10) 2 pin male and female relimate connectors.

Component List for Delay and firing unit

1) ATTINY85 SOIC

2) MOSFET 2N7002CK SOT23 Surface-Mounted Device (SMD) plastic package

3) Inductor L1 of 100uH (EIA 0805)TDK MLF2012

4) Capacitor C1 is 4.7uF (Tantalum chip capacitor) 35V(EIA 1210)TRJ series AVX

5) Capacitor C2 0.1uF (0402)ceramic capacitor used at the input(Vishay).

6) Diode(schottky diode)10MQ060N.

7)TVS diode surface mount TRANSZORB transient voltage suppressor by

Vishay,D0214AA(SMBJ)package,partno.P6SM56CA. Connect TVS 12v breakdown

(1mm*1mm) diode and 0.1uf Capacitor (1mm*1mm) on the other side of the PCB.

8) Thick film chip resistor SMD Resistor R1,R2,R3 SMD 0805 R1=15K ohm, 0805

R2=1K ohm R3(0805) leave 1.4mm*1.4mm for SCB do not connect R3(it is


component created in diptrace with dimensions 1.4mm*1.4mm) connect SCB

instead of R3}.


APPENDIX II

Softwares used in the project are listed below

1) Dip Trace 2.4.0.2(Freeware version)

2) PROTEUS 7.7

1) Dip Trace

The software used for designing the double sided PCB of the delay and firing unit

is Dip Trace version 2.4.0.2 (Freeware version). Dip Trace is quality Schematic

Capture and PCB Design software that offers everything to create simple or complex

multi-layer boards from schematic to manufacturing files. There are different modules

in Dip Trace for the following tasks

a) Schematic capture

b) PCB layout

c) Creation of libraries

d) 3D Modeling

a) Schematic Capture

Advanced schematic tool with support of multi-sheet and multi-level hierarchical

design that allows the designer to connect pins visually, without wires, using net

ports, buses, or logically. Electrical Rule Check and hierarchy verification work from

the earliest stages of design till the work is done. Schematic supports import and

export of different EDA/CAD and net-list formats.

b) PCB Layout

High-quality board design tool of the DipTrace environment. PCB Layout features

smart placement and routing tools, shape-based auto router, copying hierarchical

blocks, smart project structure, and verification features that ensure accuracy even for

the most complex projects. Real-time DRC allows the designer to fix errors on the fly

and increases quality all the way to project completion. Import and export a wide

range of EDA, CAD, net-list and manufacturing formats.


c) Library Creation

Cross-module library management system with component and pattern editors and

direct import from outside the DipTrace design environment. Component and Pattern

editors support smart library structure and fast creation of components and patterns

with integrated templates. Bulk pin naming, pad numbering, and editing features

allow the designer to build multi-part complex components and patterns with

hundreds of pins faster than ever before.

d) 3D Modelling

Works as a part of PCB Layout and Pattern Editor. The 3D module allows the

designer to preview the board with installed components on any design stage, rotate

and move it in real-time with hardware acceleration. Board 3D model can be exported

to mechanical CAD (STEP, VRML). DipTrace imports 3DS, VRML, STEP, and

IGES files as 3D models. 3500+ models are supplied free of charge.

2) PROTEUS 7.7

Proteus Professional - software was used for PCB design of the Setter and for

simulation of the setter and firing and delay unit. It is a software for automated design

of electronic circuits. The package is a system of circuit simulation, based on the

models of electronic components in PSpice.

A distinctive feature of the package Proteus Professional is the possibility of

modelling of the programmable devices: microcontrollers, microprocessors, DSP and

others. Additionally, the package of Proteus Professional is a system design of printed

circuit boards. Proteus Professional can simulate the following microcontrollers:

8051, ARM7, AVR, Motorola, PIC, Basic Stamp. The library contains the

components of reference data Co-simulation of microprocessor software within a

mixed mode SPICE simulator. Available for PIC, 8051, AVR, HC11,

ARM7/LPC2000 and Basic Stamp processors. See your code interact with simulated

hardware in real-time.


Interactive peripheral models for displays, keypads, etc. Over 8000 analogue and

digital device models. Extensive single step and debugging facilities including system

wide diagnostics. Works with popular compilers and assemblers. Professional

schematic capture and PCB design software with automatic component placement,

track routing and design

validation. Includes full feature schematic capture environment. Create PCBs

automatically or manually from a schematic. Extensive support for power planes.

Outputs to industry standard CADCAM formats. Integrated 3D Viewer provides

board visualisation during design. Interactive SPICE circuit simulator included with

all versions.

Integrated Pyro SCB Chip

Documents