It depends on who manufactures your BGA devices, where they get their solder
balls from and most importantly how good is your solder stenciling process....
From what I have seen in my facility, your +/- 0.001" is actually excellent
assuming that your tolerancing is derived statistically and not from standard
deviation data....

Marcelo

        -----Original Message-----
        From:   Eric Christison [SMTP:[log in to unmask]]
        Sent:   Tuesday, October 13, 1998 10:55 AM
        To:     [log in to unmask]
        Subject:        [TN] Tolerance on Collapsed height of BGA Balls

        I am having difficulty in believing something a packaging engineer is
telling me.

        We have a design of sensor which is now BGA packaged. The balls are
0.030" diameter and 0.023" high.
        After reflow I am assured that the collapsed height will be 0.019"
+/-0.001"(given a correctly
        dimensioned footprint) . I have no problem with the 0.019", it's the
+/-0.001" that stretches my
        credibility threshold.

        Is there anyone out there that can confirm or deny this tolerance?

        Regards,




        Eric Christison

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