Lately, we are experiencing leakage (low resistance values and noise) at
temperature in laser trimmed resistor networks which have been potted in
silicone.  As received, parts test out O.K.  The parts are hand soldered
into an assembly using RMA flux, cleaned in a vapor degreaser in AK225AES,
coated with silicone primer and then potted in silicone. I know resistor
networks are very sensitive to chloride contamination. I suspect a sensitive
enough test will find a number of sources for something as common as
chloride but how much is too much? Any suggestions on how or where to look.
We are going to try testing parts at various stages of our process to try to
isolate the problem but I suspect we are looking for something that is very
subtle.

Your suggestions will be greatly appreciated.

Mary M. Davis
Materials & Process Engineer
ELDEC
[log in to unmask] <mailto:[log in to unmask]>
425-743-8327

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