Kevin:
Below are Wolfgang's & Jim's info... Contact Jim for his chart...
Regards,
Bill Davis, Ph.D.
Diamond Multimedia Systems
Senior Scientist
Tel. 408.325.7868
Cell. 408.888.5650
e-mail: [log in to unmask]
======================================================================
x/y = 10-12 *10^(-6)/K (Klein-Wassik: softsolder in the elektronics, or
how
it may be called in a non-german edition)
Kett-richtung (bended fibers) 12* 10^(-6)/K (privat comunication by an
sellman)
Schuss-Richtung (straight fibers) 14-15 * 10^(-6)/K (privat
comunication by
an sellman)
z = 50-70 10^(-6)/K (privat comunication by an sellman)
Hope it helps
Wolfgang Nuechter
=======================================================================
I have a comprehensive chart which I can fax you, if you want to provide
the
phone #.
Generally, Z-axis is 60 to 80 ppm (or microinches/inch/C), X is 17-20
ppm, and
Y is 15 to 18 ppm. Lots of variables however:
a. These values are for a temp ramp up to the Tg, which is 135C
typically for
FR4.
b. Remember that FR4 today can be a material with a Tg as high as 180C.
Higher Tg FR4's tend to exhibit a slightly lower Z-expansion below the
Tg than
135C types.
c. Z-axis is particularly affected by resin:glass ratio. Higher Resin
content means greater expansion, which has to be considered in high
layer
count designs.
d. Above the Tg, the X and Y movements get squirrelly because the
softened
resin allows the glass fabric to pull back against the expanding matrix,
resulting in much lower values.
jimpaulus
>
>
>
-----Original Message-----
From: Kady, Kevin P [mailto:[log in to unmask]]
Sent: Monday, November 30, 1998 9:37 AM
To: [log in to unmask]
Subject: [TN] FR4 properties
Hello,
I am interested in the material properties of FR4, particularly, the
coefficient of thermal expansion. Can anyone help?
Thank you,
Kevin Kady
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