Hi Randy,
>The device in question is a memory device from Austin Semi. P/N As8512K32
>http://www.austinsemiconductor.com/products/flash/as8f512k32.pdf
>This is a 68-CQFP device with KOVAR leads. The leads from the mechanical
>view are an "L" configuration with a small 0.25mm offset. Austin claims the
>lead offset is to compensate for CTE mismatch. Compliant leads equates to
>ductile leads? I think KOVAR is very stiff and probably not very ductile.
>Are there IPC or MIL guidelines that could help me?

I do not know this particular device, and I do not have a clear picture of
that lead geometry--I do not understand the 0.25mm offset.
Lead ductility is not the issue, modulus of elasticity is [quite high for
Kovar]  and lead geometry.
Lead compliancy in lbs/inch can be calculated [see papers be R. Kotlowitz]. I
have found in the past that device manufacturers know little about the
mechanical properties and behavior of the components they make; Austin Semi
may be the exception, but I would not bet on it. Look at IPC-D-279, Appendix
A for guidelines.

Regards,
Werner Engelmaier

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