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labnotes/_source/_posts/2024-05-01-cosmac.markdown

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post Building a COSMAC/RCA CDP1802 learning computer 2024-05-01 13:00:00 +0200 true

PCB making

Printing the transfer

I tried several methods to prepare the toner transfer intermediate:

  • baking parchment paper with double sided tape
  • glossy magazine with scotch tape
  • glossy magazine with glue

What seemed to work best is the glossy magazine glued to a sheet of paper strong enough to not have irregularities. ⚠️ Don't forget to mirror the image before printing 🤦

Preparing the board

Grain #500 sandpaper -> steel wool -> acetone

Transferring the toner

  • 1st attempt (glossy paper taped to carrying paper, max heat, 1.5 min): failure the paper sticks to the PCB, no transfer
  • 2nd attempt (parchment paper glued to carrying paper outside of printing zone, max heat, 3 min moving across surface, let cool): much better, good enough for silkscreen but probably not for etching
  • 3rd attempt (glossy paper glued, pre-scrubbed with isopropanol):
    • very good print, almost no defects
    • transfer with acteone/alcool (3:8): total failure, did not stick to copper at all.
  • parchment paper, taped to carrying paper on all sides (outside of printing zone), pre-cleaned with isoprop
    • iron 2 min on each part of the surface, temp setting 2, lots and lots of pressure
    • let cool completely
    • transfer failed :-(

Looking for a laminator...