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
- 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:
- Eagle: http://www.cadsoftusa.com/, free CAD software (free as in free beer)
Components:
- Digikey: http://www.digikey.com/, huge catalog, convenient parametric search
- Selectronic: http://www.selectronic.fr/ and also a shop at Nation
Tutorials:
- Adafruit, instructables, arduino forums, ...
Professional PCB services:
Finding a fun project:
- Yourself !