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Reply To: | TechNet E-Mail Forum. |
Date: | Mon, 30 Nov 1998 19:22:29 EST |
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Hi Kevin,
The CTEs of FR-4 are as follows:
a(x,y) ~18±2 ppm/°C <= CTE-constraint from glass cloths
a(z,<Tg)~50 to 85 ppm/°C, a(z,>Tg)~240 to 390 ppm/°C
As you can see, there are quite some ranges in these values, depending on
glass cloths, resin content, amount of copper, etc. Thus, if you need accurate
values you need to measure them; do so both below and above Tg (do not
average).
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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