Hi Bing,
Are you using Noflow prepregs? Noflow prepregs are precured, which means the
resin is brought beyond the point of lowest viscosity in the cure cycle with
the crosslinking of the polymer chains beibg interupted where the viscosity is
high enough for no lamination flow but still gives you tackiness. This is a
tricky process because the crosslinking, once started proceeds rapidly. Thus,
Noflow prepreg is not all alike and staorage conditions/duration also makes a
difference.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask]

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