Hi All -

Well here we go again with another one of those "you can't get there from
here" questions.

We're looking at the conversion of a VME sized CCA from use in benign
environments to use in severe service environments.  The design is about 80%
surface mount.  We've conjured up the necessary stiffeners, etc., for the
board and have most of the problems worked out EXCEPT for three PBGA's about
1.25" square.  These 1.25" pitch devices have finned aluminum heat sinks, to
add to their mass.

The final laminate material hasn't been selected, but I would expect to go
with IPC-4101/26 or better to obtain a fairly high Tg.

Has anyone had any experience with MIL temp range thermal cycling and
vibration of PBGA's in this size and structure?  ... and if so, with what
degree of success?

Would appreciate any comments.

Have a good day - Kelly

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