In a message dated 5/5/99 11:37:37, [log in to unmask] writes:

>Which is an interesting experimental concept. Why hasn't this been done?
>If we can't agree on acceleration factors, why doesn't the industry do a DOE
>with a leg or 2 being actual life and other legs being acceleration tests to
>determine factors for different constructions/components/surface 
finishes/.....
>Or has this been done?

Hi Steve,
This has been done—with mixed success, thus 'we can't agree on (or do not 
know) acceleration factors' in many cases. Some degradation mechanisms are 
only active at (highly) accelerated (read: more severe) test conditions, 
e.g., CAF. Others are dependent on such a complex interaction of different 
parameters, that nobody has been able to properly model them. Still others 
degrade in ways not easily measured. And others, like solder joint and 
PTH/PTV reliabilty have been successfully modeled and acceleration factors 
can be determined.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com 

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