In a message dated 96-10-20 18:06:19 EDT, you write:

<< One of our customers recently asked " Is there any correlation between
 Ionic contamination testing (SEC) and surface insulation resistance
 testing?" It has been my understanding that the tests probably reflect many
 of the same contaminants but that there may be some not detected by one or
 the other test. Is this impression true? If so, what types of contamination
 may not be detected?   >>

Yes and No.  A definite maybe.  Sort of.
The correlation now is a loose one at best.  In general, as ionic residues
rise, SIR will degrade.  How much degradation depends on the ionic species
involved and the amounts.  SEC testing will tell you if you have a material
which is conductive in solution, but not what the composition is, or if the
materials are detrimental.  Some elements, such as weak organic acids, will
show high levels in an SEC test, but are benign insulators on a board
surface.  The link becomes much better between ionic data as measured by ion
chromatography (IPC-TM-650, method 2.3.28) and SIR testing.  Another factor
is the SIR test profile used - static, cyclic low temp, high temp, etc.  An
SEC test will not detect a polyglycol material, which can degrade SIR.  SEC
will not pick up the presence of non-ionic organic compounds, which can
degrade SIR.

Doug Pauls
CSL
Chair, SIR Task Group

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