Hi Technet Gurus!

I have attached a picture of a part responsible for excess current draw during an extended humidity/temperature cycling test. (I copied Steve so he can hopefully post!)

The board was carefully solvent cleaned, but no SIR test validating the process strips all ionic contamination.  The board is in an enclosure where plenty of ionic contaminants are available.

Humidity was supposed to not exceed 90% and was to be non-condensing during cycling.  There were a handful of components which displayed similar deposits on the same circuit board.  These were the only parts biased during the humidity test.  I believe the evidence suggests at least some condensation occurred.  To me the deposits look like salts.   But what do "the experts" think?

Is there any rule of thumb as to humidity levels where we are nuts to try to survive without conformal coating?  Part of the adjacent circuitry contains RF devices and those guys get panic-stricken when told we probably need to conformal coat!

Wayne Thayer

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