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. ---------- From: [log in to unmask] To: [log in to unmask] Subject: [TECHNET] CTE with CIC