what is magnetic property (demagnetized initially-de gauss? what  
happened if it over the life time of the device... any restriction  
that not allow to use near the magnet)?  what is corrosion resistance  
(salt spray)?  what is electrical conductivity over temperature range  
from -55 to 150C?  thermal conductivity? what is dissimilar metal  
coupling?  what is storage shelf life and condition?  alloy 42 is  
intended  to match semi/ceramic package to prevent minimum CTE stress  
over the temp range.  what is the most important stuff you try to  
protect?  in what environment?
On Nov 7, 2017, at 8:40 PM, Julie Silk wrote:

> 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