Hi Michael,
With a CTE-constraining to about 10 ppm/C, you have tobe very careful that
you do not get delamination when you cycle -55C<=>+125C. The solution to the
delamination typically is a thicker more compliant bond layer, but than the
CTE-constraint works less effectively.
Q: Why -55C<=>+125C? This temperature cycle does not exist anywhere but
misguided specifications.

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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