Mr. Jee:

We may have something that can assist.   Some time ago, we figured out that a
number of people are having your problem, and we suspected that it may be due
to the mask reacting with some Copper oxides that are on the surface when
they are baked.

We also realized that the only way to realistically solve this problem was
with an alkaline cleaner, as acid cleaners, or microetches, will render any
mask residues insoluble, and seal off the area needing to be cleaned.  The
problem was that any alkaline cleaners we looked at also attacked the
soldermask.

We did a lot of research into this, and finally figured out that there
actually are chemicals that can prevent attack on the soldermask.  Maybe
"prevent" is too strong a word, better, "minimize dramatically" any attack.
 We have done a survey of masks available in the US, and the cleaner does an
excellent job on any mask we have seen, without attack, at up to 165 F (74 C)
for 15 minutes, not that you actually need to run it this long.

This cleaner is in use at a couple of shops, and most notably seems to cut to
essentially zero the need to re-HASL boards, they get excellent coverage
first time through.

The big reservation on this product is that it cannot be used as the only
cleaner in a pre-HASL (or other finish) line, as it will remove light
tarnish, but nothing like the sort of thing that you see after baking boards,
so an acid cleaner, or microetch must be used with it.

Would be happy to give you more information, or send you a sample.

Rudy Sedlak
RD Chemical Company
Mountain View CA
fax 415-962-0370

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To subscribe/unsubscribe send a message <to: [log in to unmask]>   *
* with <subject: subscribe/unsubscribe> and no text in the body.          *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************