Steve:

You finally asked something that I can answer!  Thanks!

The problem of adhesion of Dryfilm soldermask to bare Copper is a legend, and
it is NOT your cleaner, almost certainly.  Dryfilm soldermask does not adhere
to Copper well.  H-P (remember them, they used to make PCB's) had an
especially, ahh, "interesting" test for soldermask adhesion, where they
floated the board on molten solder for 1250 hours, or some such, and no sort
of cleaning could get them through the test....and they further said that
essentially all cleaning gave the same results, whether chemical, or
mechanical abraision.

However, oxide made the soldermask stick so strongly that you had to destroy
the mask to get it off.....

So, we formulated an oxide chemistry for them that they sprayed on, that was
SO light you could not see it.  We got to calling it the "Emporer's Oxide",
as only the faithful could see it!!!!

They had some non-believers (at H-P) that at one point, removed panels from
the oxide line, and put soldermask on them to see if they could tell a
difference between panels that had been run through the oxide line, or not.
THERE WAS, BIG TIME.

This is a bit extreme, to consider oxide under soldermask, but it do work,
and is the best possible bond enhancer.

Hope this helps, in some way.

Best,

Rudy Sedlak
RD Chemical Company

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