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Date: | Sat, 2 Aug 1997 16:48:57 -0400 |
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In a message dated 97-08-01 00:10:33 EDT, Mark Ploughman asked for
coefficients of thermal expansion (CTEs):
ANSWERS: below are orders of magnitude:
Polyimide materials: ~ 60 ppm/C.
Polyimide based boards: x-y CTE ~ 15 to 18 ppm/C, z-CTE ~ 65 ppm/C
FR-4: x-y CTEs ~ 16 to 18 ppm/C. This is typical of in-plane CTEs for
double-sided boards, but measurements have given numbers in the range 12 to
21 ppm/C, depending on construction and board features (vias, solder filled
holes, amount of copper etc...). z-CTE: 60 to 85 ppm/C.
Copper: ~ 17. ppm/C
Jean-Paul
_______________________________________________________________
Jean-Paul Clech
EPSI Inc., P. O. Box 1522, Montclair, NJ 07042 - USA
tel: +1 (973)746-3796 fax: + 1 (973)655-0815
Home page:
<A HREF="http://members.aol.com/Epsiinc1/index.html">http://members.aol.com/Ep
siinc1/index.html</A>
(last updated on June 28, 1997).
SMT / BGA /CSP assembly reliability specialists.
- click on the above or copy: http://members.aol.com/Epsiinc1/index.html
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