Jim, send me the stack-up specifics and I will check the model for you. I
have 2 different modeling programs.


At 07:28 AM 11/15/2005, you wrote:
>Hello,
>
>If there are any impedance testing gurus out there I have a question for
>you.  We are testing an edge coupled offset strip line coupon.  We modeled
>the stack up to give us 100 ohms differential.  When we test the coupon we
>get around 130 ohms.  We have done a microsection of the coupon and modeled
>the coupon data and Polar says we should have 105 ohms, within tolerance.
>We had a 4 panel lot and it is consistent across the board.  The coupon is
>constructed correctly.  My question is, other than what I am seeing on the
>microsection should I look for to find the culprit of the high reading?  Any
>help would be great.
>
>Jim Henderson
>Colonial Circuits
>
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