Phil;  Perhaps what your looking for is the equations in IPC TP 706 A
Military Airborne Application of LCCS on Copper Invar Copper and Kevlar
based PWB's.  Page 13 has the Taylor/Pedder equation for cycles to failure
and page 14 has a formula for estimating the composite CTE for a proposed
PWB configuration followed by some case studies.
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Subject: [TECHNET] CTE with CIC