Kevin,

Have you considered a different heatsink material e.g. SiC reinforced Al?
You could match its TCE to the ceramic and perhaps revert to a standard
PCB material.

David Whalley

>I am working with a design that requires CTE management for solderjoint 
>fatigue of a leadless ceramic component, and I am considering random fiber 
>aramid pwb construction.  The problem I have is that the solder side copper 
>heat sink modulus is almost 10X that of the pwb and the results of the 
>composite heat sink assembly is of little benefit of CTE the component sees.
>
>Can anyone recommend a heat sink/pwb adhesive that is forgiving enough to 
>allow the expansion differences while still having good properties of 
>shear/peel strength and thermally conductive?
>
>Thank You in Advance,
>Kevin Thorson