gnupic: Re: [gnupic] PCB blues - any suggestions?
Subject:
[gnupic] PCB blues - any suggestions?
From:
Bill Freeman ####@####.####
Date:
30 May 2005 16:49:30 +0100
Message-Id: <17051.13875.85968.686418@localhost.localdomain>
David McNab writes about home PCB transfer film woes:
How are you preparing the copper before the transfer? Let me
suggest scrubbing with a "Scothch Brite" or "Toughy" (plastic fibers)
pad and a solution of distilled water and tooth paste (about equal
parts). rinse with distilled water (poured from the top edge while
holding the board on a slant in the sink). Immediately dry in a warm
oven (60 to 80 C, support by the corners so that the useful part of
the board doesn't touch the oven grill) for about 2 minutes. Do not
touch the target area of the board with fingers or anything else oily
between the wash and the transfer. Do the transfer reasonably
promptly, so the board doesn't have time to oxidize.
That may be overkill, but I've had a lot of trouble getting
toner to stick to boards that haven't been aggressively cleaned.
Actually seeing finger prints, or things that match the shape of
surface discolorations of the copper (oxide, usually) in the pattern
of bad adhesion is a big clue.
You might need a bigger iron. As with soldering, the copper
needs to get above the melting point of the wax in the toner in order
for the wax to wet to the copper. So long as the board is reasonably
flat, you shouldn't need a great deal of pressure.
You might also try a different printer. Toner formulations
vary. (I've actually had good luck with HP, but the black they use in
the color printers might be different.)
All that being said, I should confess that I haven't used the
secondary transfer method. I was instead part of a project
experimenting with using a modified printer to print directly on the
copper. I expect that much of what we learned applies to secondary
transfer, however.
Bill
