Have you heard of component terminations made of “pure iron”? Not an alloy. Any concerns that I should know about? Seems like the CTE is low, although not as low as alloy 42. These are plated with copper then Sn5Bi. Rather odd... Comments from our materials engineer: Per existing guidelines, Alloy 42 is a high risk in SMT because of CTE mismatches with Sn. CTE of pure Fe is 11.7 ppm/C CTE of Cu or alloys ranges from 16.2 to 17.8 ppm/C CTE of Sn is 23.5 ppm/C CTE of pure Alloy 42 is 4.6 ppm/C