Hello Folks,

We've been experiencing BGA solder joint failures due
to what appear to be fractures at the solder joint.
After reflow, the joints don't appear to mechanically
stressed, so we suspect it to be related to variant
rates of thermal expansion.

Does the theory sound correct ?

Is this common ?

Does anyone know approximately how much differential
movement I can expect between the board and the BGA if
the package is .500 sq. or so ?

Thanks,

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