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Steve
Our experience with similar problem as yours would indicate the combination
of using dry film and the high concentration of Aquanox is probably the root
cause, not surface prep. Since you are experiencing flaking on both
metalized and non-metalized areas indicates random attack of the Aquanox at
this concentration. Surface prep problems would be indicated by repeatable
areas showing the flaking.
Try reducing the concentration level to 5% to see if the problem goes away.
This approach will effect your cleanliness level of the product, but it would
confirm the attack at the higher concentration level.
Another test is to use a processed assembly through all thermal transitions
(final) (maybe from your scrap pile if you have any). Place a few drops of
your cleaner solution at your current concentration level (30%) on metalized
and non-metalized areas of the board. Also place a control drop of DI water.
Let the assembly stand for 8 hours at ambient. The drops should evaporate
over this period of time. Perform a peel test on the drop areas to
investigate mask liftage.
Contact me off line if you need more info.
Hope this helps.
Regards,
Pat Kane
Technical Sales Manager
Contamination Studies Laboratories
765-457-8095
Hi All!
Maybe some of you remember quite a while back, I had a problem with some
boards with the soldermask flaking off all the copper after 3-cleanings in
our MCS-1000. It's basically a fancy-smancy batch cleaner. We use Kyzen
Aquanox XJN at between a
25-30% concentration (recommended by Kyzen). We also run our wash temps at
140º F., and our rinse at 120º F.
Back when it happened last time we narrowed things down to the soldermask not
being able to take the Aquanox, it was a dry-film (Dynachem Dynamask). We had
other boards that had dry-film on them that we built and showed no
ill-effects from the cleaning. I looked into things and learned that these
boards were masked with a Dupont 8100 series dryfilm...so made it a point to
specify Dupont dry-film on the boards that require dry-film.
Well guess what? I'm starting to see the problem again. Our fab vendor swears
up and down they used a Dupont dry-film. What I see, is that after the second
wash the mask will start to "bubble" and lift on the vias (and sometimes the
traces too), the film hasn't broken yet (it's still intact, it appears to
just be lifting from the copper), but after you wash the board the third
time, the mask starts flaking off all the copper... vias, traces, everywhere.
So I guess I'm starting to wonder now if it's really a mask compatibility
issue with the Aquanox, or is it possibly something about the quality of the
surface prep prior to solder masking?
Have any of you seen this before?
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