Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Hi all, i've been testing a way to make photo etching cheap'n easy. I
went to a Screen-print shop and bought photosensitive emulsion, the
cheapest type. I mixed the components and painted the emulsion on the
copper. Then I let it dry overnight in a (pitch) dark place.
On a transparency I printed the negative of my circuit and placed the
transparency, toner side to the emulsion and placed it under a
fluorescent lamp for 7 minutes or so. I removed the board and nothing
seemed to change, until I ran some water over the board, and with a
hair brush for babies (the softer-than-hair type) i helped the water.
The exposed areas dried up but the rest washed with water. GREAT
precision, SMD quality. Then I let the board again now in the sun to
totally burn the emulsion and it was ready for etching, warm (hot)
ferric chloride.

Hope that helps.
Some day I'll try the AZO-based emulsion, but that one needs UV curing.