Kathy ,
            We do many impedance boards and the vast majority of our customers want to see results traceable to the
panels any board came from. We add  impedance coupons representative of the board design ( 2 per production panel ) and
serialize them to the boards in that panel. We test  and supply data from these coupons in a report . The coupons are
in some cases also supplied to the customer but in most cases are held for a period of time in case retest is required.

 Regards
Paul Greene , Rexcan Circuits

Kathy Bergman wrote:

> Hello and Happy Independence Day (almost):
>
> We manufacture PCB's. We are just beginning to do TDR testing in house.
> Is there anything in the IPC standards that I can use as a guide in
> determining what percentage of a lot is a representative sample of the
> results? Would you, as customers, require to see a 100% verification (a
> value for each board), or would you be comfortable with a representative
> lot report. I am writing a work instruction, and TDR Certificate for the
> process.
>
> Your help is appreciated.
> K. Bergman
> Quality Manager
> ICPC Etched Circuits
>
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Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
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