Hi Guenter,
This large anisotropy for PCBs with Kevlar woven fiber reinforcement is very
interesting. What were the CTEs in the x- and y-directions? Even with
standard FR--4 there frequently is some x,y-anisotropy of about 1 to 2 ppm/C.
The non-woven Kevlar matte you refer to will eliminate the anisotropy, but
the CTE-constraint will be significantly less than you would get with uniform
woven Kevlar. To you have a paper on this study-please send it to me.

Werner Engelmaier
Engelmaier Associates, Inc.
Electronic Packaging, Interconnection and Reliability Consulting
23 Gunther Street
Mendham, NJ  07945  USA
Phone & Fax: 201-543-2747
E-mail: [log in to unmask] 

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to:           *
* [log in to unmask] with <subject: unsubscribe> and no text.        *
***************************************************************************
* If you are having a problem with the IPC TechNet forum please contact   *
* Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask]      *
***************************************************************************