If you are trying to "qualify" a process, the question becomes "Qualify to
what standard"?  Presently, there are no bare board cleanliness
specifications (on a national basis).  The closest would be the Bellcore
document.

I would recommend imposing the SIR and Electromigration tests of Bellcore
TR-78, Chapter 13, as well as using ion chromatography per IPC-TM-650, method
2.3.28.  The ion chromatography, if done properly, can tell you if you will
have electrical leakage or corrosion problems with the fabbed boards.  The
SIR tests and Electromigration tests will get the bad actors.  In our
testing, passing the Bellcore SIR and electromigration tests will not always
catch problems.

I would not rely on ionic cleanliness tester information alone, and I would
be leery of any fab house that uses ionic cleanliness testers (e.g.
Omegameter, Zero Ion) alone to show cleanliness.  I have lost track of the
number of problems we have looked at in which the ICT data showed under 5.0
ug/in2, but had leakage and corrosion problems.

If you would like to discuss it further, please call myself (Doug Pauls) or
Terry Munson at (317) 457-8095.  We provide the services listed above.

Doug Pauls
Contamination Studies Laboratories
Kokomo, IN

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