[jluetjen]

I work in the semiconductor packaging industry and we deal with this issue all the time. The science is very inexact and little understood. The last time that I checked, I don't believe that they can even be grown on a predictable basis. On the other hand I've got one customer who has a 5lb slug of Sn that was pulled out of a solder tank that looks like a porcupine on his desk.

Yeah, the Aero-Def and automotive industries would like SnPb solders to go on forever. Meanwhile most countries are clamping down on their use and so most of the consumer and commercial companies are phasing them out fast. That means that in the future only a few boutique manufacturers will be equiped to support SnPb. There are things that can be done to manage the problem, some of which are:

1) Bake the soldered item which stress-relieves the surface.
2) Pot or coat the soldered item.
3) Replace the Sn plating with an anternative like NiPdAu (Nickel - Paladium - Gold)