Pretty hard to overcure Polyimide with that high a Tg. Too long at
high temperatures can make the material more brittle.
Hope your using one with Tg of 240-260 (similar to the old 601, 601A
resin that is no longer available). Some of the new ones have
significantly lower Tg.


Since Polyimide resin systems now vary (no more 601A) from supplier to
supplier The supplier should be consulted. In general the heat rises
are similar to FR4s but the material is usually significantly thicker
than FR4 while it is flowing. Higher pressures than FR4 are typical
but not really needed for all builds; depends how much you are
actually filling.

Tg can be done anytime. DSC or TMA is ok; I prefer DSC.
At lest one formula requires two cure times / temperatures and time at
the higher temp. does NOT count for the first required time at the
lower temp.

[log in to unmask] wrote:
> Technetters:
> I'm looking for information on the best way to confirm cure on a
> polyimide board.  The particular part is a sequential lamination
> structure.
> My questions include:
> 1.  Is the best time to confirm cure of polyimide immediately after
> final lamination?
> 2.  Do the polymers created require a specific cure test, e.g. is TMA
> best, DSC, or other method?
>
> Also, can overcure be a problem with Polyimide?
>
> And, does this material offer special challenges with respect to gel
> time, resin flow, etc?
>
> I've already heard differences of opinions, and am looking forward to
> more avenues of knowledge from Polyimide experienced folks.
>
> Mark Julstrom
> Multek---------------------------------------------------------------------------------
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