I read in sci.electronics.design that Daniel Haude wrote (in ) about 'Lead-Free Solder: Weird Behavior', on Tue, 22 Mar 2005:
Oh, that's not playing fair! You aren't allowed to introduce a 14 T magnet halfway through the speculations! (;-) Even so, your current-carrying interconnections are prey to electromechanical disruption. And BE VERY careful about using tin (Sn) at even modestly low temperatures. Look here, and elsewhere with the search string tin*allotropes:
ISTR that a few years ago, doubt was cast on whether 'grey tin' is really an allotrope, rather than an intermetallic compound, but it seems to have been redeemed.