Do any of you have experience with the removal and repair of Motorola PBGAs.
The assembly giving me grief has a 503 and 360 ball PBGA located within a
quarter inch of each other.  I have found that the PBGA (flip chip package
on the top of the component) tend to be more themally sensitive than other
BGAs during repair so I shield the one not being replaced.  I also suspect
that the component is more moisture sensitve than its MSD class 3 would
indicate so boards requiring replacement are baked 24 hr @ 125o C prior to
removal and replacement.  Still I have very spotty success.  It seems that
removal and replacement of a "bad" one may blow the good one.(?)  The
shielded unit may see 150 - 180o C at its top surface, the one being
replaced stays below 240C.  I am using a Conceptronic Freedom 2000 with hot
Nitrogen at 330C.  Profile shows ball temp > 183C for about 30 seconds on
the replaced part.  I do not have the ability to pre warm the board to 60 or
80C prior to the repair and suspect it could be counter-productive even if I
could.

George Carroll
Process Engineer, Siemens Energy & Automation
P.O. Box 1255
3000 Bill Garland Road
Johnson City, Tennessee 37605
(423) 461-2948
[log in to unmask]

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