Soldermask UV ink/paint/epoxy
2013-03-30 by James
So I've been doing some (more) experimenting with UV cure soldermask
ink, I wondered if anybody had any tips to add.
Photos:
Copper
Side:http://www.flickr.com/photos/93638530@N08/8601556485/in/photostream
Component
Side:http://www.flickr.com/photos/93638530@N08/8602656700/in/photostream
(no copper on the component side, I inked it just to get a more
reflective surface, it's a board full of LEDs).
There are effectively a couple of individually cured coats on both sides
since I tried various ideas.
Technique: spread thin layer ink, smooth a piece of polyethylene
plastic bag over it with a cardboard squeegee, expose, peel off plastic,
wipe pads clean.
Apart from the alignment (which Is just a matter of better practice or
mechanical technique), the really hard part is getting a SMOOTH coating
without air pockets on top, the stuff is really sticky, and spreading an
even thin layer under the plastic I'm finding very difficult.
I've tried thinning it with acetone, mineral turpentine, and kerosene
with various results, even the tiniest drop (literally, a drop) of
acetone makes it like water, it still cures OK and it's mostly smooth,
but it's a bit too watery I think and may be the cause of the chipping
shown in the photos. Turps and kero don't really combine with the ink
at all, but seems to make it a smoother.
I've tried rolling the ink on using a foam art roller, and it just sort
of stipples (a very uniform and thin coat, but stippled) and applying
the plastic on top is no easier.
I'm thinking maybe if I rolled it on, then sprayed the plastic with
turps, or maybe acetone, and applied that, it might work better.
I also drilled it after I had applied the mask, as you can see on the
bottom (which was just a straight coat, no pad masking, single sided
board) where the drill went through the soldermask sometimes chipped
off, I think this is probably due to thinning the mask ink down which
affected it's adherence. It also made it a bit tricky to drill in
general, due to the slight misalignment the mask on a couple of
occasions mis-directed the drill bit, I'm thinking about drilling it
first then applying the solder mask, although I'm concerned about
cleaning out the holes adequately.
Also considering getting some perhaps thicker polyethylene plastic.
Any other suggestions?
ink, I wondered if anybody had any tips to add.
Photos:
Copper
Side:http://www.flickr.com/photos/93638530@N08/8601556485/in/photostream
Component
Side:http://www.flickr.com/photos/93638530@N08/8602656700/in/photostream
(no copper on the component side, I inked it just to get a more
reflective surface, it's a board full of LEDs).
There are effectively a couple of individually cured coats on both sides
since I tried various ideas.
Technique: spread thin layer ink, smooth a piece of polyethylene
plastic bag over it with a cardboard squeegee, expose, peel off plastic,
wipe pads clean.
Apart from the alignment (which Is just a matter of better practice or
mechanical technique), the really hard part is getting a SMOOTH coating
without air pockets on top, the stuff is really sticky, and spreading an
even thin layer under the plastic I'm finding very difficult.
I've tried thinning it with acetone, mineral turpentine, and kerosene
with various results, even the tiniest drop (literally, a drop) of
acetone makes it like water, it still cures OK and it's mostly smooth,
but it's a bit too watery I think and may be the cause of the chipping
shown in the photos. Turps and kero don't really combine with the ink
at all, but seems to make it a smoother.
I've tried rolling the ink on using a foam art roller, and it just sort
of stipples (a very uniform and thin coat, but stippled) and applying
the plastic on top is no easier.
I'm thinking maybe if I rolled it on, then sprayed the plastic with
turps, or maybe acetone, and applied that, it might work better.
I also drilled it after I had applied the mask, as you can see on the
bottom (which was just a straight coat, no pad masking, single sided
board) where the drill went through the soldermask sometimes chipped
off, I think this is probably due to thinning the mask ink down which
affected it's adherence. It also made it a bit tricky to drill in
general, due to the slight misalignment the mask on a couple of
occasions mis-directed the drill bit, I'm thinking about drilling it
first then applying the solder mask, although I'm concerned about
cleaning out the holes adequately.
Also considering getting some perhaps thicker polyethylene plastic.
Any other suggestions?