I remember 2-3 years ago asking similar question and someone told me that
copper-invar-copper is already a thing of the past. Unfortuntately, I have lost that
message. Hope to hear what others can offer after these years.

Regards.

Phil Dutton wrote:

> Hello,
>
> I'm wondering if anyone can give me any information on the design of
> conduction cooled boards for use in an airborne military environment?
> I'm intending to use VME size boards with a copper-invar-copper constraining
> core, and an aluminum stiffening frame with wedge-locks.
> Is there any problem with using FR4 or FR5 material, or should I be looking at
> something like Polyimide or BT/Epoxy?
> Is it commonplace to use SMT devices (QFP)?
> Also, there are few manufacturers here with any experience producing such
> boards, so any pointers to possible manufacturers would also be appreciated.
>
> thanks,
> Phil.
>
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