George

I did the DK after both a temperature soak at 125oC and 150oC and the DK
dropped about 0.1 lower than the fresh sample in both cases.  I assumed that it
had to do with driving out the moisture instead of any change in the
resin/laminate.  The tests we were running were on boards that did not have any interest
in impedence control and the DK test was only for curiosity and I do not know
the frequency that the measurements were made at. The soak time in both cases
was 100 hours.

Phil Hinton

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