Question about going Pb-free

[Sparks]

   For a while I've been wanting to go RoHS compliant and the largest hurdle for me has been the dreaded Lead free solder. I have heard of the tin whisker problem yet have never experienced problems from it. My question is about the high tin content in solder reacts to cold environments. Does the so called tin pest occur in electrical solder?

[jmelson]

pure tin solder or plating plus moisture plus retained stress seems to be the recipe for the whisker formation.  I saw some whiskers on a particular batch of Xilinx chips that had pure tin plating, plus the gull-wing leads were apparently formed AFTER plating.  I was using a tin/lead solder, so did not heat them enough to anneal the tin plating, and whiskers grew, RIGHT at the bends, only.

I do a lot of manufacturing with SAC305 solder, and have not had any problems with those boards.  That is about 1000 boards in the field, but almost all P&P and reflow, not hand soldering.

Jon