Paul 
In a previous session I related information on bakeing epoxy and polyimide
boards.
The epoxy boards on which I was running tests tests were 10 layer ml
finishing at 0.093 in.  The ml cure cycle was such that it was in for 45 min
after it reached temperature of 175 deg C in the press.  DSC's showed 0-2 deg
change after lamination.

The polyimide were also multilayer, 12 layer

To my best knowledge, the shop did not have any problems with the higher bake
temperatures or delaminations in later product. 

In another case of a ml, measles that were attributed to moisture absorption
was not eliminated by a 4 hour bake at the supplier and a 4 hour bake at the
user at 125 deg C  just prior to loading.  However, a 1 hour bake at 10 deg C
above the Tg of the material solved the problem, the Tg of the material 145
deg C. (Stress relief, not moisture removal, was perhaps the function of the
bake).

The above and previous info seems to indicate that we do not know everyting
about moisture in circuit boards and perhaps a simple drying at slightl;y
obove the BP of water is not always the answer.      

Phil Hinton 
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