pixelcanvas wrote:
> I used acrylic paint as a solder mask, actually I painted it after
> soldering, just to keep the traces from rusting.
Invest in a pressure pack of solderable PCB lacquer . It makes rework a
lot easier, my can is about 10+ years old and I still use it..
> I'm printing the masks on inkjet tranparency paper, but I'm having
> problems with that because when the ink dryes it craks leaving very
> thin lines, in fact I'm surprised that such thin lines remain after
> etching. So I have to use a marker to cover the cracks, but still some
> remained on the mask and that's what causes those little spikes along
> the traces.
You should take photos of your transparency and another of the
photoresist film directly after development.
Form the shapes of the copper slivers it looks to me you have an
exposure problem, and not a developer problem.
Developer problems cause either damaged/peeling dry film or an invisible
resist scum, that inhibits etching in tight corners.
If the ink is cracking then you have the wrong transparency type for
your inkjet ink. That should never happen.