Lecture SMEMA SMT Conveyors Student Version

Modern Electronics Manufacturing

SMT Line Configuration

1Modern Electronics Manufacturing by Dr. Shahid Khan

•SMT Line Configuration Basis•Full Single Pass Double Sided Type 1 Line

Configuration•SMEMA Interface

SMT Line Configuration Basis

Modern Electronics Manufacturing by Dr. Shahid Khan2

SMT lines are configured based on the following:The level of automation.The type of SMT style to be made.The line volume based on actual CPH.The board component mix.Components on one or both sides.PCB to be assembled in one or two passes.The level of in-line inspection. AOI at each

step or just after reflow, or offline.And last but not least, the amount of funding

available.

SMT Line Configuration by Dr. Shahid Khan










Conductive PCBMagazines

Off LineX-RayInspection

SMT Line ConfigurationLine Throughput Calculations


Pick and Place Machine ThroughputThe total catalog CPH of all six mounting

machines in the line is (40K+40K+20K+40K+40K+20K)=200K CPH theoretical. In reality, based on the component mix, this would translate into approximately half of this, or 100K CPH actual.

If we assume a double sided PCB panel with 4 repeats. Each repeat has 300 components on the top and 300 on the bottom.

Each panel thus has 1200 components on the top and 1200 on the bottom.

Placement time for a side would be 1200/100,000 hours or 43 seconds.

SMT Line Configuration by Dr. Shahid Khan Line Throughput Calculations


Printer Throughput:In a typical production printer, the PCB IN/OUT

time is approx 15 seconds.And the print time is typically 15 seconds.So, if the printers are producing a print every 30

seconds, they would keep up with the placement machines as it typically takes a few seconds to input and register a panel on the mounters.

To increase the printing throughput, the PCB panel size could be increased by increasing the number of repeats, from 4 to 6 or even 8, within the limits of the max. PCB size that can be handled on the conveyors and the machines.

SMT Line Configuration Line Throughput Calculations


Reflow Oven Throughput:Typical solder paste has to be in the oven for

around 270 seconds (due to the profile). A large oven is typically 5 meters long.

So the PCB would travel 5M in 270 secs or 18mm /second.

If the PCB panel was 300mm by 150mm and it was traveling with direction of travel parallel to the 150mm side, with 30mm between each panel.

The time for a panel to exit the oven would be (150+30)mm / 18mm/sec = 10 secs.

So, if the mounters are producing a panel every 86 secs, the ovens can easily keep up.

SMT Line Configuration by Dr. Shahid Khan Line Throughput Calculations


Total Line Throughput:This would be based on the limiting throughput,

which is of the Pick and Place Mounters.They are producing a 4 repeat panel every 43

seconds.So panels produced in an eight hour shift is

8x3600/43 = 670 panels per shift, or 2680 PCBAs per shift.

Or 8,040 PCBAs per day on a 3 shift basis.Or 192,960 per month based on a 24 day month.Or 2,315,520 PCBs per year.

SMT Line Configuration by Dr. Shahid Khan How to Connect them Altogether?


We have just configured this huge double sided SMT line.These machines will be made by a number of different

machine manufacturers on different sides of the globe.How is it ensured that they work together and seamlessly

pass PCBs from one to the next?Enter the “Surface Mount Equipment Manufacturers

Association”.To cover this issue and make all the machines work

together, they came up with a standard called IPC-SEMA-9851.

This defines a very simple but highly effective way of getting disparate conveyorized machines to hand off to and receive PCBs from each other.

SMT Line Configuration by Dr. Shahid Khan SMEMA Interface


Introduction: The SMEMA machine interface standards were developed to facilitate the interface of equipment used in the assembly of surface-mounted printed circuit boards.

The mechanical specifications that follow are for single board transfer systems with conveyor transports.

Conveyor Height Each machine shall have the trans-port conveyor height adjustable from 940 to 965 mm [37 to 38 in] from the floor to the bottom of the PC board.

Fixed Rail For the purposes of this standard, the front rail is defined as the fixed rail.



Conveyor Width For equipment with an adjustable conveyor width, the front rail is fixed and the rear rail is adjustable. The range of adjustment will vary with the equipment manufacturer.

Edge Clearance The conveyor should require no more than 5 mm of clear board space at the side edges.

Tooling Pins Tooling pins, if used, should be on the front edge of the board (next to the fixed transport rail). A recommended hole diameter is 4 mm. Distance from the edge should be 7.6 mm.

SMEMA Interface


The maximum unsupported gap as defined by G in above figure is 19 mm.

SMEMA Interface


Lead-in The minimum lead-in on the track ends of the conveyor is 3 mm and the angle shall not be greater than 30° as shown.



ELECTRICAL INTERFACE REQUIREMENTS: A machine-to-machine electrical interface is

required to insure proper sequencing of PC boards. The interface is used for "Local" control and shall operate independently of the cell controller.

Inter-Machine Control To sequence boards properly from machine-to-machine, the "Board Available" and "Machine Ready" signal lines will he used and "Board Pass/Fail" signal line is optional.

Connectors All interface connectors on a machine shall he female.

SMEMA Interface


EL

SMEMA Interface


Connector Cable

Function Condition Description

Pair 1 -2 (Note 1)

Machine Ready to Receive

Contacts Closed

(Notes 2,3)

Machine is ready to receive next board.

Pair 3-4 (Note 1)

Board Available

Contacts Closed

(Notes 2,3)

Machine has a good board ready to send. Allboards are considered to be "good" if the BoardFail option is not being used.

SMEMA Interface


Pair 5-6 Auxiliary Interface Power(optional)

Available: user to document purpose andoperating parameters.

Pair 7-8 (Note 1)

Failed Board Available(Optional)

Contacts Closed (Notes 2,3)

Default (no connection or. if used, contacts areopen) is that the incoming board is good and suitable for use. Optional use is to provide closed contactswhen it has been determined

SMEMA Interface


Pair 7-8 (Note 1)

Failed Board Available(Optional)

Contacts Closed (Notes 2,3)

that the board should stop transfer or bediverted. In such cases, these contacts shallbe closed in lieu of (and not in addition to) thenormal Good Board Available contacts.


Pin-out of SMEMA Connector

SMT Line Configuration by Dr. Shahid Khan, SMEMA Interface

SMEMA Interface – Logic Signals


Board transfer occurs when Machine A has a BOARD AVAILABLE (contact closed) And Machine B is MACHINE READY TO RECEIVE (contact closed).The signals can occur at any time, but board transfer does not occur until both contacts are closed.The BOARD AVAILABLE signal from Machine A will remain closed until the board has left Machine A.

The MACHINE READY TO RECEIVE signal will remain closed until Machine B has positive control of the board.

Board transfer cannot occur again until each signal opens for at least 50 ms.Optional: Once both Machine A and Machine B signals are closed, and the board has neither left A nor arrived at B. an error message will be generated (to be defined by users).

SMEMA Interface –Timing Diagram for Normal Transfer


SMEMA Interface –Timing Diagram for NG Board Option




End of Lecture(Reading: Posted Lecture Notes on SMT Line Configuration and SMEMA Interface)

Lecture SMEMA SMT Conveyors Student Version

Documents

shahid khan shahid khan

line volume

line inspection

huge double sided smt

pcb panel size

type of smt style

double sided pcb panel

repeat panel