Since I didn't see anyone else answer your question, I thought I'd give it a shot.
The modulus for FR-4 laminates is in the 10^6 - 10^7 psi range if I remember correctly (the book on electronics materials by Pecht et. al. gives more precise figures, but I no longer have access to a copy) and depends on direction, due to the directionality of the glass. The glass is always at right angles to the axes of the panels.

Best Regards,
Timothy Reeves
Technical Service Engineer - Matsushita Electronic Materials, Inc.
4114 Heather Street, Forest Grove, Oregon, 97116
Main (503) 357-8695     Direct (503) 992-5109    Cell (503) 781-1495     Fax (503) 357-8868


-----Original Message-----
From: Eric Christison [mailto:[log in to unmask]]
Sent: Thursday, February 13, 2003 9:31 AM
Subject: Stiffness of FR4?


Can anyone give me some stiffness values for FR4 - probably a Young's modulus
although I realise that isn't strictly correct?

Also, am I correct in saying that all the fibres run at 0 or 90 degrees i.e.
there aren't any layers where the warp and weft run at 45 degrees across the
board?

Thanks,



--
Eric Christison
Mechanical Engineer
STMicroelectronics
33 Pinkhill
Edinburgh
EH12 7BF

tel:    +44 (0)131 336 6165
fax:    +44 (0)131 336 6001

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