Building Circuit Boards
at home


2014-01-07

ParisEmbedded#3


martin@mbonnin.net

http://mbonnin.net

Breadboard


Easy but:
  • fragile
  • takes space
  • can become very messy very quickly
  • no SMT (Surface Mount Technology) components

Arduino/Launchpad/your favorite devboard


Powerful but:
  • not very flexible (limited choice of shields, ...)
  • can be expensive
  • takes space
  • still no SMT

Outsourcing


Professional service offers quality but:
  • Delays are long (few days at best). Iterations take time.
  • Minimum orders
  • Might be a bit expensive and overkill for simple DIY projects


DIY circuit board


  • Iterate quickly
  • Make the PCB the size you want, using the components you want
  • It is a great opportunity to learn

3 main techniques:
    • CNC milling  (CNC = Computer Numerical Control), no chemicals involved :-)
      • ...but requires a CNC machine
    • UV exposition + Iron chloride 
      • ...a bit dirty
    • Toner transfer

Toner Transfer technique

You'll need:

  • Copper clad, uncoated, ~15$/A4 sheet,  digikey
  • Hydrochloric acid, 2€ leroy merlin
  • Hydrogen peroxyde, 7€ leroy merlin
  • Glossy paper (supermarket ads are perfect), free
  • Laminator, 25€ amazon (or steam iron)
  • Acetone, 3€ leroy merlin
  • Laser printer



 


1/4.printing


  • Print the board layout
  • Do not forget the 'mirror' option !


2/4.transfer!


  • As the paper is glossy, ink does not adhere to it and can be transferred to the copper clad
  • This takes time...


     

3/4. Etching

  • Use a mix of tap water, hydrochloric acid and hydrogen peroxyde (100/60/40)
  • The toner protects the copper so it is not removed under the PCB traces


4/4.Cleaning up


  • Clean up the remaining toner with acetone
  • And you've got your PCB :-)


SMT soldering


  • The technique can do traces up to ~8mil
  • This is precise enough for some SMT packages:
    • DIP of course
    • SOIC
    • some SSOP
  • I like SOIC and SSOP because:
    • it saves the drilling part
    • soldering is actually easier and much faster than DIP packages: flood with solder and remove the excess wid braid

Other benefits


  • Include touch sensors
  • Include mounting holes
  • Include the power supply for portable projects
  • Sign your board :-)


Getting started:

Resources

Schematics and board layout:

Components:
Tutorials:
    • Adafruit, instructables, arduino forums, ...
Professional PCB services:
Finding a fun project:
    • Yourself !





Questions ?

building_pcb_at_home

By mbonnin