Hi Ken,
I have been asked this question before from our exempt and excluded customers. First thing I would do is ask if the part manufacturer has done any Sn whisker testing, and if yes, request for the results. From there you can take the help of the following to determine your risk:
JESD22A121.01: Measuring Whisker Growth on Tin and Tin Alloy Surface Finishes, and
JESD201: Environmental Acceptance Requirements for Tin Whisker Susceptibility of Tin and Tin Alloy Surface Finishes; and
JEDEC/IPC joint publication JP002: Current Tin Whiskers Theory and Mitigation Practices Guideline
On our end this was a joint exercise, with us, as the CM, and our customer. Now, the JESD201 does mention that high Sn alloys are not generally allowed for class 3 applications, but hopefully, the data you get from the component manufacturer will help to draw objective conclusions about the risk of Sn whiskers in your application.
Hope this helps,
Amol
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bloomquist, Ken
Sent: Wednesday, January 24, 2007 1:25 PM
To: [log in to unmask]
Subject: [TN] Lead-Finish Question
Here's a question for all the high rel people out there. We've received
a couple of notifications from major component suppliers that they will
no longer supply the parts we need with a SnPb finish. Instead they are
only supplying them with "Matt (Matte) Tin" finish. They do not talk
about any under plating which would be desirable for minimizing tin
whiskers.
How are you people who build for DOD and medical handling these
situations? Am I being too sensitive about Matt Tim?
By the way these are single source and SMT parts.
Thanks in advance,
KennyB
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