For those who don't know, Vitrea 160 is a heat cured glass paint (as in
for painting glass) which can be used as a DIY soldermask and is
available easily at many art supply stores for a few dollars in a large
number of colours. The typical use is to use toner transfer to put
toner on your pads, then brush (or better, spray with an air brush) a
slightly diluted vitrea coating, allow to dry, then bake at 170-180
Degrees C for 30 to 40 minutes (technically you're supposed to dry it
for 24 hours, but I thin with methylated spirits, air brush it, and just
allow it to dry for a couple hours before baking, no problems). Once
baked, acetone and a cotton bud will remove the toner leaving the pads
clean.
Example produced today:
http://www.flickr.com/photos/93638530@N08/11885554945/It's not just for looks, it does do a reasonable job as a soldermask,
once baked resistant to abrasion, chemicals etc and as long as there is
flux around solder doesn't stick to it.
Anyway, long story short, it works well if you use toner transfer to
mask out the pads, given it's only the pads you're transferring, that's
not a great hardship but I'd rather use dry-film for masking the pads
somehow. I tried painting the board then applying & exposing &
developing the resist over the top, and subsequently using a solvent to
strip the paint from the now exposed pads, but the solvents I've tried
are also happy to strip the resist off too.
Brilliant ideas anybody?