Hi David,
Now I'm no surface finish expert or metallurgist for that matter, but is it
possible to do a solderability test and maybe a pull strength test on some
of the components in question? Seems to me that the solderability test would
answer your question about if shelf life has impacted the ability of the
components to form the proper solder connections. Additionally, it seems
that the pull test would give some indication into the strength of the
intermetallic joint that has been formed. Just a couple of thoughts that I
had this morning while reading your inquiry.
Best Regards,
Joe Russeau
Process Analyst
Precision Analytical Laboratory, Inc.
4106 Cartwright Dr. Ste. A
Kokomo, IN 46902
P: 765-455-1993
F: 765-455-1996
E: [log in to unmask]
----- Original Message -----
From: "David Britton" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, April 11, 2006 2:31 PM
Subject: [TN] Shelf Life Policy Inquiry
> 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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