Steve,

        I'm sorry about referring to you by the last name previously, however,
it's not the first mistake I've made today ha!ha!
I understand the quandry that you are in and can appreciate the problem. I know
for a fact that there is a company out there that is working on this very
problem. At this time I cannot reveal the company as they are trying to verify
that they can indeed do this with adequate accuracy. (a lot of help this is
now). Sorry about this but currently, I'm sworn to secrecy.
        Perhaps in the near future the technology will mature, and they will
make a lot of people very happy. So there is hope, but it may take a while.

Regards,
Les

>  From: "Joy, Stephen C" <[log in to unmask]>, on 12/18/98 7:31 AM:
>  Les,
>
>  The problem with TDR is that everyone has a good P/T but can't correlate to
>  anyone else.
>
>  My search for a non destructive method of checking dielectric spacing is to
>  find
>  a mechanical way to measure impedance.
>
>  I am only concerned with trace perimeter and dielectric thickness. Dk is
>  more
>  difficult to measure and I hoped I could make it a constant at the nominal
>  impedance value we fix and the construction we specify. I know we are not
>  the
>  PCB experts, but the tolerances are so tight that we need at least to create
>  a
>  consensus from the PCB manufacturers for construction.
>
>  Is there any hope here or am I just wasting my time?
>
>  Thanks for all the responses on this.
>
>  Steve
>
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