Lou: Since you "are reviewing everything about our cleaning process",let me
add a few things to consider.

Your original post was regarding analysis of the saponifier
concentration.This can be done but be careful. Most saponifiers are made up
of a variety of chemical components. The concentration can be accurately
checked for a new make-up, typically using an acid/base titration and
checking normality. However as the wash bath ages and depletes though the
introduction of flux, board contaminants, dragout etc. the individual
chemistries(surfactants,detergents,chelators) can be selectively depleted.
The accuracy of the analysis after the bath has been in use can be
misleading, resulting in a false sense of its cleaning capability.
Another point of concern is the bath will become loaded with both ionic and
non-ionic contaminants. Due to the low surface tension of the wash cleaning
chemistry these contaminants can become entrapped under components. The
higher surface tension of the rinse waters can not sufficiently remove
them(keeping the rinse temps 10 degrees warmer than the wash helps).
Obviously if your board design is susceptible, this can lead to signal
alteration.

My advice is if you have sensitive circuitry don't try to push the wash life
too far. It's much cheaper to dump and make-up a fresh bath before it gets
you into trouble.


Regards

Michael Barmuta

Staff Engineer

Fluke Corp.

Everett Wa

425-356-6076

-----Original Message-----
From: Lou Hart [mailto:[log in to unmask]]
Sent: Monday, February 07, 2000 10:13 AM
To: [log in to unmask]
Subject: Re: [TN] Saponifier concentration measurement


Thanks, Alain.  We are reviewing everything about our cleaning process.
Kester tech reps said we should use titration.  Our production guy says it
will take too long.

Lou

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