Printed Circuit Board Design

Printed Circuit Board Design

Design Team 6Alex Volinski

Derek BrowerPhil Jaworski

Jung-Chung LuMatt Affeldt

Software Flow Routing / Board Layout Components/Assembly Electrical Considerations

Introduction

Software Packages Schematic Advantages Schematic creation

◦ Libraries◦ ERC and simulation

Schematic to Layout

Software Flow-Schematic

Layout◦ Libraries◦ Layers and Routing◦ Labels◦ DRC

Fabrication

Software Flow-Layout

Important Terminology◦ Layers

Metal Silkscreen Solder mask

◦ Traces◦ Spaces◦ Trace/Space

Routing/Board layout

Important Terminology◦ Pads

Surface Mounts◦ Vias

Drilled Metal Plated Holes

Routing/Board layout

Layout by importance of Position Align componentsin a common-senseapproach

Floor Plan

Regulators

Sensor IO

Sensor IO

Memory

User I/O

Micro-controller

JTAG

USB/UART

Routing in PCB Artist◦ Place components inside green PCB border◦ Yellow lines are connections that need to be made

Floor Plan

Floor Plan Layout Example of 2-Layer Board

◦ Bottom Level Grounded

Floor Plan Begin Making Traces

Tracing Problem

Floor Plan

Grounding Techniques◦ Series

Common Impedance◦ Parallel

Low Potentials High Impedance

◦ Multipoint Contains Currents Reduces Inductance

Floor Plan

Power Distribution◦ Single-Point

Single Reference◦ Multipoint

Impedance Coupled◦ Star Distribution

Central Reference Equal Lengths

Floor Plan

Through-hole◦ DIP

Surface mount◦ SOIC◦ BGA◦ QFN

Component Types

Surface Mount◦ Stay above 0805

Through Hole◦ Much easier and

less performance

Assembly Techniques

Solder Reflow◦ Allows precise soldering of Surface Mounts (below

0805)

Assembly Techniques

Decreasing impedance vs. protecting a section

Return Path

Ground Plane Traces

Multi-Layer board is capacitor

Stray Capacitance

Avoiding Radiating EMI At ‘low’ frequencies (<100 MHz) no

components will be antennas Be aware of attached cables Layout board to reduce coupling

Avoiding Antennas

Software Flow◦ Advantage of making schematic◦ Layers, Libraries, Fabrication

Routing / Board Layout◦ Layers, Traces, Pads vs. Vias◦ Importance of position◦ Grounding Techniques, Power Distribution

Conclusion

Components/Assembly◦ Different types of components◦ Through Hole / Surface Mount◦ Weighing options for better performance

Electrical considerations◦ Stray Capacitance ◦ Ground Plane Traces◦ Antennas to avoid radiating EMI

Conclusion

Questions