I did a first experiment with the UV-lamp + Transparency + Presensitized-Board method.
Using a randomly drawn pattern, this was my (promising but unsatisfactory) result:
What could typically be the culprit behind such speckles, i.e., the patchy-nature of the copper rectangles/lines?
For the record, this is my method:
- Print pattern on transparency
- Print pattern again on same transparency (double toner = double mask darkness)
- Place transparency on presentisized board (positive photoresist), and hold down flat using plexiglass
- UV exposure (with 13-watt CFL bulb) for 8-9 minutes
- Develop in NaOH + Water for about a minute (at end, there was clear contrast between the pattern and the rest of the board)
- Etch in FeCl with periodic agitation by hand