Folks,

For those caring, my final summary of this thing is as has been stated. As
Werner puts it, the first thing bad is the asymetric device construction.
This means coplanarity is compromised because of the aluminum heat sink atop
the part and attached directly to the hot Silicon part. This causes the PCB
substrate to warp.

The second issue points to the reason Tessera is successful. They used a
compliant flex layer to ensure CTE matchibng characteristics are not
compromised as in the case of the TI device wheren its die is directly
attachd to the PCB substrate.

Therefore, two failure mechanisms are at work. Each or both are capable of
effecting poor initial quality solder joints and negatively impact long term
reliability.

Thanks all on and off line,

Earl Moon

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