Hi MoonCaveMan,
I had thought YOU had come out of your cave. I am currently babysitting for
my 3 granddaughters in NC.
Steve says: it is a 384-ball .8mm pitch PBGA with a heatslug on the top...
If it is in fact a PBGA with a heatslug on the top, than it is a SBGA--these
are notorious for warping when you change their temperature because they are
of a thermally asymetric design. I have seen solder balls ripped of the pads
and soldering pads ripped out of the PCB.
You could also be right about the silicone affecting the global expansion
mismatch with the PCB. TI has just agreed to license their microStarBGAs
under Tessera's patents to avoid infringement [Sharp's CSPs were found to
infringe Tessera's patents]. But it is not just CSPs that might have their
BLR affected by the die; larger BGAs that are thin can suffer from the same
problem.

Werner Engelmaier

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