Sorry Jim, but I respectfully disagree.
I want my engineering info straight. From what Nelco gives me, I cannot
determine the thermal expansion from 25 to 230C, from 0 to 180C or anything other
than 50 to 260C--that is simply not acceptable and lousy technical information
to boot.
We certainly understand the impact of Tg, but
Why not give CTE values below and above Tg; that way everybody can determine
what they need. While, of course, the thermal expansion to soldering
temperatures is important for the reliability of   the PCB interconnect structures, it
is not enough for the more severe environments like those for military and
automotive products. This is particularly important in the z-axis, since that
determines the loads on both the Cu barrel and the innerlayer connections to the
barrel.

Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com


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