Technet,

I have a large (2 inch) BGA that I am designing a PWB for.  Where can I find
information on how much movement from TCE (thermal coefficient of expansion) mis-match
can a solder joint be expected to live with.

I have calculated that the parts will see less than .25 mm of movement from solder
temperatures to room temperatures and .02 - .03 mm of movement over typical operational
temperature cycles.  I expect the BGA to have .75 mm (30 mil) balls on it.

I am looking for something to tell me when I am "close enough", or give me some kind of
"MTBF feeling", so I can judge the risks in the design.

Thanks

George Franck
Raytheon, Falls Church Va

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