In a message dated 03/22/2000 4:11:05 PM US Eastern Standard Time,
[log in to unmask] writes:

>         How do all of you in the no-clean world monitor and control board
>  cleanliness.  In the days of OA flux, we used an Ionograph or Omegameter to
>  monitor our 'cleaning' process.  Do some of you still use an ionic
>  contamination tester or do you use SIR testing or nothing or what?

Wade,
How did you do process control before you went no-clean?  You can still use
an Omegameter or Ionograph (or other such instrument) as PROCESS CONTROL, but
you have to throw out everything you know about "good" adn "bad" numbers.
Those instruments work for process control, but not for accept-reject.   The
result that you get will probably be higher, because the weak organic acid
activators come off of the board and make the isoproapnol-water solution
conductive.  The materials are benign on a board surface.  You should do some
correlation studies between accelerated electrical testing, such as burn-in
or life tests, and Omegameter readings.  Determine what maximum reading
correlates to failures in such accelerated testing.  Then use that as your
maximum control limit.

Doug Pauls
CSL

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