During our resent lead free evaluation it was discovered that several of our
component vendors are changing their finishes from tin- lead to pure tin.  Quite
often this change is being made with no part number change, so these part are
getting to our manufacturing floor without anyone knowing they have a different
finish.  This has lots of people's attention due to the Hi Rel nature of most of
our products.  We have narrowed our concerns to two:  tin whiskers and solder
joint reliability.  There is a lot of work being performed on tin whiskers.  Do
you see the pure tin component finish impacting the tin- lead solder joint
metallurgy to the point of impacting high or low cycle fatigue??  Typical I
would think the component finish would be a small percentage of the total volume
of the solder joint, resulting in minimal impact.  But I'm afraid the
inter-metallic layers maybe impacted, resulting in changed reliability.

The opinions of this group would be valued.


Scott Newland
Harris GSCD
321 727 6472
Pager  321 690 4131
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