Hi Dave,
You say:
"From companies like Marconi you can put parallel units in the field that are
subjected to a range of environments that should cause failure. Tracking of
these units must go on for 10 years plus depending on the application."
Well, it does not quite work this way--and do you really want--[can afford
to]--to wait for 10 years, particularly in the face of the 2006 deadline?
Tracking field failures has been largely unsuccessful in the past, when many
more resources [Bell Labs, IBM, Motorola] were available.
After all, that is why we have accelerated reliability tests and modeling in
combination. All [!? ;)] one needs to do is to design the accelerated tests
properly--clearly no small feat in the absence of a full understanding. We are
now struggling to adopt IPC-9701 for LF and are running into the
"Don't-know-enough"-wall.
Unfortunately, I have yet to see any evidence that this is done anywhere, or
that even tests are underway to give us some data base that would allow the
development of an acceleration model--with the possible exception of the group G
ünter Grossman works with.
At this time I certainlly cannot recommend any LF-solders for
high-reliability applications.
Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com
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