Hi Jonathan,
You are absolutely correct--it is not the same to cycle -40<=>85 or 0<=>125;
that was established by Roger Wild, IBM, in the 1970's. In the cycles above,
you will get significantly more complete creep with accelerated testing of
0<=>125; with -40<=>85-cycling you may get a confounding of damage
mechanisms, depending on the solder alloy. Absent the mechanism confounding,
the cycling at  the higher T-range will give you shorter fatigue life.

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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