In a message dated 12/19/00 1:55:29 PM Eastern Standard Time,
[log in to unmask] writes:

<< I have a large quantity of double sided boards(.062/140Tg) that have
severe warp with memory. We have performed "dewarp" (three hours at 300F then
cooling to ambient temperature under weight)baking using press caul plates
several times with no success. >>

Hi Tony -

For what it's worth you're following the same procedure we use.
Beyond that:

Q1: Is your stack height not greater than 1"?

Q2: Is your material Nanya?

Q3: Is the distribution of drilled holes and routed features close to uniform?

Q4: Are there any large internal cutouts?

Q5: Have you tried running the boards through a press cycle? (you might
consider running between caul plates at a reduced temp...perhaps not higher
than 275).

Bob Lazzara
Circuit Connect, Inc.

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