Recently, our Contract Manufacturer has been asking for approval to use
parts that are 4-6 years old.  Due to the lifespan of some of our
products, it appears that the frequency of requests is increasing.

For the recent request, my choice is to approve the use of 6 yr. old
parts, or wait up to 16 weeks for new parts.  I am concerned about
possible solderability issues and the potential for damage/degradation if
the parts were not stored properly over that time.

We currently do not have a shelf life policy but it seems like we need to
have some position. I can only find a couple of references to an "accepted
practice" of a 2-year shelf life used by manufacturers.  One other
Engineering Bulletin from EIA about Tantalum Caps, states:
"Solid tantalum capacitors have no known wear-out mechanism or shelf-life
limitations.  However, solderability and cover-tape peel strength may be
affected by storage conditions. Consult individual manufacturers’ data
sheets for recommended storage."

Suggestions or recommendations welcome.

Regards,

David Britton
Quality Engineering Manager
Danaher Motion - Santa Barbara, CA

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