From: Larry Miller (firstname.lastname@example.org)
Date: Mon Jun 12 2000 - 13:52:42 PDT
If you got, like, 65 ohms the problem is that your dielectric thickness is
too big. If you want 8-mil traces you should be more like 0.005".
There is a handy-dandy impedance calculator available for free download at
UltraCad.com that I use all the time for "close enuf" PCB trace
> -----Original Message-----
> From: Sean Murray [SMTP:email@example.com]
> Sent: Monday, June 12, 2000 1:35 PM
> To: 'firstname.lastname@example.org'
> Subject: [SI-LIST] : DIFF PAIRS
> Anyone have any thought on what to use for the following numbers.
> Material: CE
> Impedance: ZO of the differential trace is 50Ohm and ZOD of each
> differential pair traces is 100Ohm.
> I built a board using 8 mill traces with a 8 gap between the pair, and
> .008 gap between plane to sig and then plane.
> Numbers were not what I expected, fabhouse used Polar+fudge factor to
> give me the numbers.
> Sean Murray
> General Manager
> M&M Specialties Inc.
> 1236 W. Southern Ave. #106
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