[Elecraft] [OT] Re: How Tin-Whiskers Form

[aj4tf]

The fact that stress gradients appear to propagate tin whiskers has been
known for some time.  (in fact, the phys.org authors should have researched
their own web site more thoroughly:  
http://phys.org/news173450615.html#nRlv)

At my place of employment, we also are concerned about the impacts of RoHS
parts (RoHS = non-lead-bearing) and their impact to long term reliability of
electronic assemblies.  We don't make things that go into space, but we make
things that are nearly equally inaccessible once they are installed. 
Recently we performed an experiment on an assembly to attempt to induce tin
whisker formation by temperature cycling it hundreds of times over the
course of over 6 months.  At the end of the experiment, only one component
(out of hundreds on the assembly) showed any signs of whisker formation.  
Even with RoHS parts, using lead-based solder paste to assemble the boards
partially (but not completely) mitigates the risk.

David AJ4TF




--
View this message in context: http://elecraft.365791.n2.nabble.com/How-Tin-Whiskers-Form-tp7566988p7567225.html
Sent from the Elecraft mailing list archive at Nabble.com.