Charlie,
If you have a digital oscilliscope such as and HP 54120 and know the
line length then you can measure the propagation delay and back
calculate the effective Er from that.

Regards,

Alan B. Cochrane
CTO
PC World Inc.
"The First Choice in Printed Circuit Technology and Service"


> "Charles E. McMahon" wrote:
>
> Hello Tech-net:
>
> What method (hopefully non-destructive) would be used to determine the
> dielectric constant of an existing 4ly circuit board. The spec's call
> for 4.3/FR-4 however we are not sure what we received and the vendor
> is not responding as of yet.
>
> Your response is thanked for in advance.
>
> Charlie McMahon
>

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
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
##############################################################