Hi Dave,
>        a.      Question:  With one ball in the middle not touching and
>the balls next to it are, is this indicative to SMT process issues or
>BGA package issues?
A:  This could be either, unless solder paste deposition had been verified. I
f it is not a paste issue, than it is BGA package warpage.
>        b.      Question:  What type of inspection can be performed on
>BGAs prior to SMT to capture Bad BGA?
A:  Get warpage data for the  BGA package.

>        f.      As indicated above, pressing down the package causes the
>board to pass, how do I detect micro cracking of the solder joint? And
>what would cause micro cracking?
A:  ENIG "Black Pad" causes 'brittle' interfacial cracking.

Werner Engelmaier

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