Having manufactured both hi-tech cleaning machines and sophisticated 
ionic contamination testers in the past, I concur with what Steve Pence 
stated. I held a patent (now in the public domain) for what was 
essentially the opposite: an ionic contamination tester that doubled as 
a cleaning machine (I never put it into production as lab tests proved 
that it was inefficient as a cleaner). In reality, cleaning machines 
with recirculation through DI and carbon columns were never brilliant as 
not all contaminants were removed, depending on the spectrum of 
adsorption of the carbon, which could not cover all the molecules coming 
off the boards. For this reason, all our machines had an open circuit 
final rinse with fresh carbon-filtered DI water. In fact, we stopped 
making recirculatory rinse machines in 1978, even though the final rinse 
was open circuit. All our later machines, until we stopped making them 
in 1997, were 100% open circuit DI rinse, using a unique economical system.

Brian

- bogert wrote:
> July 26, 2007
> 
> I have a question to pose for Tech Net folks based on my limited 
> experience in this area.  If I have a cleaning machine that includes a 
> built in continuous test for rinse water or wash water resistivity, do I 
> need to then still do an independent ionic contamination test using the 
> standard DI Water/Alcohol Ionic Contamination test?  If so why?  What is 
> the technical relationship between the two tests?  Can one equate the 
> cleaning machine Resistivity Test results to the J-STD-001 cleanliness 
> limits or the results of the Ionic Contamination test?  If so, how?  
> Have folks experience shown that one can pass the cleaning machine 
> Resistivity Test and still fail Ionic Contamination Test?  Why?
> 
> Doug, Pauls, as the worlds (wow) expert in this area, what do you say 
> (It depends)???.
> 
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