Printed Circuit Board Anarchy DriveBy ITP - November 13, 2006 Nick Sears – Michael Ang –

What we’re going to do Comparison of prototyping techniques Comparison of prototyping techniques Designing a board Designing a board Schematic capture Schematic capture Board layout Board layout

What we’re going to do (contd) Making a board Making a board Output file generation Output file generation Online fabricators Online fabricators DIY DIY Resources and links Resources and links Surface-mount soldering demo Surface-mount soldering demo

Breadboard vs Protoboard vs Printed Circuit Board

Breadboard Fast! Fast! Susceptible to vibration, dropping Susceptible to vibration, dropping Can document with good photo Can document with good photo Easy to debug Easy to debug

Breadboard Being neat is worth it! Being neat is worth it! (don’t do this) (don’t do this)

Protoboard Cheap! Cheap! Slower than breadboard Slower than breadboard Hard to capture layout Hard to capture layout Good reliability Good reliability Thought required while assembling Thought required while assembling

Circuit board More startup cost/time More startup cost/time Good debugging Good debugging Easy to make more boards Easy to make more boards Good reliability Good reliability Good for communicating design Good for communicating design Smallest! Smallest!

Design Steps Schematic capture Schematic capture Board layout Board layout

Schematic capture Add parts Add parts Connect parts (create “nets”) Connect parts (create “nets”) Create new devices (if necessary) Create new devices (if necessary) Electrical Rule Check (ERC) Electrical Rule Check (ERC)

Board Design Create board from schematic Create board from schematic Place components Place components Route traces Route traces Design Rule Check (DRC) Design Rule Check (DRC)

Common sizes Check with board house for available drill sizes and trace widths Check with board house for available drill sizes and trace widths Some provide DRC file for Eagle Some provide DRC file for Eagle Holes Holes Vias - 20 mils (or smallest from board house) Vias - 20 mils (or smallest from board house) Holes - ~50 mils Holes - ~50 mils Traces Traces 10 mils (larger for power and where possible) 10 mils (larger for power and where possible)

Board Layers Top – top traces and SMT pads Top – top traces and SMT pads Bottom – bottom traces and SMT pads Bottom – bottom traces and SMT pads Pads – through-hole component legs Pads – through-hole component legs Vias – connect top and bottom signals Vias – connect top and bottom signals Dimension – outline of board Dimension – outline of board tPlace, (bPlace) – silkscreen tPlace, (bPlace) – silkscreen tStop, bStop – soldermask tStop, bStop – soldermask (And a few more layers, e.g. for autorouter) (And a few more layers, e.g. for autorouter)

Generate Output Files Generate Gerber files Generate Gerber files Generate layer images Generate layer images

Sample Pricing Most do boards up to a given size, or full panel Most do boards up to a given size, or full panel Can put multiple designs or copies on a single board/panel Can put multiple designs or copies on a single board/panel Fabricator charges to score or cut Fabricator charges to score or cut Group orders a good idea Group orders a good idea

Sample Pricing (contd) $10 + $2.50/sq in (cheapest for small boards) $10 + $2.50/sq in (cheapest for small boards) Wait while orders are batched Wait while orders are batched Shipping included (n weeks, where n=??) Shipping included (n weeks, where n=??) $120 for 14.5x10” panel $120 for 14.5x10” panel Shipping included (~1 week) Shipping included (~1 week) Depanelize?? Depanelize??

Sample Pricing (contd) x 4x5.5” for $58 2x 4x5.5” for $58 $12 shipping $12 shipping De-panelize for $.50/piece De-panelize for $.50/piece Advanced Circuits ( Advanced Circuits ( $33 for 60 sq in (min 1 with student special) $33 for 60 sq in (min 1 with student special) Not sure about shipping Not sure about shipping

DIY Board Etching ITP Board Etching Tutorial (thanks Todd!) ITP Board Etching Tutorial (thanks Todd!) ITP Board Etching Tutorial ITP Board Etching Tutorial Use laser printer to print top and bottom layers Use laser printer to print top and bottom layers Transfer toner to copper clad board Transfer toner to copper clad board Etch away excess copper using FeCl Etch away excess copper using FeCl Put in Hazmat when done!!!! Put in Hazmat when done!!!! Drill holes Drill holes

Next Steps Design a board Design a board Get it fabricated Get it fabricated Make a nice enclosure Make a nice enclosure Have your projects travel the world Have your projects travel the world Sleep soundly at night Sleep soundly at night

Resources Blog post will be updated: circuit-boards-driveby.html Blog post will be updated: circuit-boards-driveby.html circuit-boards-driveby.html circuit-boards-driveby.html

Questions? Nick Sears – Michael Ang – (Stick around and watch Nick solder!)