Homebrew PCBs

On 01/04/13 05:49, cillino25 wrote:
> I'm very interested on this too, but I never found the right UV 
> curable white ink..could you please link the product you're using or 
> at least its name? Can I find it on the bay?

Hi, can be purchased on ebay, in 10ml syringe, and 100gram jars.

Some ebay items for you (search for "solder mask repairing paint")...

10ml Green: 281017402222
10ml Red: 170869294776
10ml Blue: 180917174704

100g Green: 350753761856
100g Blue: 190547440482
100g Red: 200784217886
100g White: 200622510695
100g Black: 281074672686

It goes a long way since you want to spread it over really thinly (if 
too thick only the top cures leaving the paint actually on the board 
uncured and so it chips off.

To apply it, briefly speaking, cover the board with the ink, or put a 
SMALL blob in the middle, put a piece of plastic over it, and smooth it 
down so you try and avoid air bubbles, then expose to artwork (pads are 
black, the rest is clear).  The exposure time is quite long (30 minutes 
in sunlight say). Once exposed, peel off the plastic and wipe the board 
with some light solvent, acetone, turps, "gasoline" as the ebay sellers 
say, the unexposed areas will wipe away.

The ink does NOT air dry, don't try drying it out before exposing, that 
doesn't work.  The plastic you choose is important, because the stuff 
will bond to many plastics during exposure which is of course bad, 
you'll need to experiment with some different plastics to find one that 
works (and let us all know what you found :)), I believe that 
polyethylene is generally the one to use, maybe polypropylene.  I'm 
currently using some old plastic press seal type bags I found in my shed 
that work (conversely other plastic press seal type bags I had didn't 
work, as I say, the exact type of plastic is important).




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