PCB production - guidelines

Note :
Protective aprons, goggles, gloves should be worn at all times in this process.
Use tongs to hold / retrieve boards - do not touch the chemicals.
If chemicals come in contact with skin wash thoroughly - immediately.
If chemicals splash eye(s) - seek attention immediately and wash eye with eye wash bottle provided.

 

Exposure
  • The actetate of artwork must be as black as possible. Go over all tracks very carefully with a permanent black fine tipped marker pen.
  • Ensure the actetate is placed on the light box such that it appears the same as viewed on screen when produced.
  • Make sure the pcb is cut to the right size to fit your artwork (teacher or technician will do this for you).
  • Pull off the black plastic protective layer on the board.
  • Lay board face down on the acetate.
  • Close the UV box and then switch both switches on the front on.
  • Expose for 3 minutes.
Developing
  • Developer will be prepared for you.
  • Developer should be at room temperature (25 degreees C)
  • Measure the temperature with a thermometer.
  • If developer is too hot the boards will strip too quickly.
  • Developing should last for about 20 to 40 seconds based temperature.
  • Developed photo-resist turns deep purple - agitate the developer until it is washed away.
  • Use tongs - wipe board with cotton wool to clear thin film of photo-resist.
  • Use tongs - wash under tap.
 50g per litre makes half strength developer suitable for use with Eco board AGS buy.
Etching
  • Etch tank with ferric chloride solution should be at 45 degrees C.
  • Place board in basket using tongs.
  • Inspect board after 10 seconds - exposed bright copper should turn red/dark pink.
  • Etching will last for 10 to 20 minutes but should be based on visual inspection.
  • Etching complete when exposed copper areas are removed.
  • Wash boards under tap the dry with paper hand towels.
    
Tining
  • Scrub off remaining photoresist using special rubber provided.
  • Tracks will appear bright copper - no green-ish areas should remain.
  • Wash board again - then dry as before.
    
Drilling
  • Drill out all holes on minidrill using a 1 mm drill bit.
  • Make sure you use safety spectacles and avoid breathing in the dust generated.
    
Population
  • Ensure all relevant paperwork (circuit diagrams etc) are at hand.
  • Collect all components required.
  • Populate all low components first (eg resistors and diodes.)
  • Then start adding taller components.
  • Carefully consider polarity requirements of compoenents.
  • Let your teacher inspect the circuit before applying power.