Hi Dave,
Your comments are well taken; I was responding to a question on accelerated
reliability testing for non-automotive use.  The temperatures you mentioned
certainly can occur for automotive electronics--that is why automotive
electronics see one of the most severe use environments-only down-hole
drilling is consistently worse.
For those applications testing in the -55 to +125C range is appropriate, but
not much of an acceleration in terms of increased severity. Shorter cyclic
dwell times for the test cycles can give you more acceleration, but those
cycles are less damaging (less creep) which needs to be accounted for. Also
because of the multiple damage mechanisms determining an acceleration
transform from which acceleration factors can be determined is generically
near impossible. One can of course establish fixed relationships for a given
test environment and a given use environment.

Werner Engelmaier
Engelmaier Associates, Inc.
Electronic Packaging, Interconnection and Reliability Consulting
23 Gunther Street
Mendham, NJ  07945  USA
Phone & Fax: 201-543-2747
E-mail: [log in to unmask]

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