We have been seeing solder fines all over some PCMCIA boards we have
build. We checked the degree of cure on the PCB, paste volume and paste
oxidation and slump and checked the oven profile (tried both a ramp-soak
and ramp to spike profile with 1 C/sec ramp rates). We then found that
it only happened when certain resistors were used. All I know right now
is that it is a RoHS (tin plated over nickel) on ceramic part- 0603.
 
We put some boards on a hot plate and heard a sizzle and popping of the
paste on a board that had these parts (didn't see the same on a printed
bare board).
What could be outgassing from the part terminations that would interact
with the paste that would cause this explosive phenomena? Could the
parts be tin plated and then fused? could it be some sort of organic
material (brightener) that is remaining and outgassing?
 
 

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