Hi Kim!
The hollow fiber means the glass fiber which  has a capillary in itself.
If the molten glass contains a sufficient level of impurities or gas bubbles,
air will become trappeed inside a fiber.
See the following material:
Anand A. Shukla,etal."Hollow Fibers in Woven Laminates" Printed Circuit Faburication,
Vol.20,No.1,p30-32(1997.1)

Regards,
Motoyo Wajima
Enterprise Server Division,Hitachi,Ltd.(Japan)


=?euc-kr?B?sei03r+1IML3wOUgwPzA2iDB9cbysPjA5cewwfq6uMH1xsA=?=  $B$5$s$O=q$-$^$7$? (B:
> Dear Technetters:
>
> Have you ever experienced or heard of hollow fiber ?
>  Is this in the state of hollowing between fibers or fiber itself?
>  For the former, I think poor soaking of resin is the cause and the latter
>is intentionally developed
>  fiber to reduce Dk.
>  Do you have any idea to improve soaking tight bundle of fiber?
>  Any comment to this is appreciated.
>
>Tal Young Kim
>Manager, Quality Assurance Team
>Doosan Corporation Electro-Materials BG
>Tel : 82-445-820-8451
>Fax : 82-445-820-8300
>E-mail:[log in to unmask]
>
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***********************************************
Motoyo Wajima
Enterprise Server Division,Hitachi,Ltd.
1 Horiyamashita
Hadano-shi,Kanagawa-ken,259-13 Japan
E-mail:[log in to unmask]
Fax:+81-463-88-2935
***********************************************

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##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
847-509-9700 ext.5365
##############################################################