[SI-LIST] Re: Finding the impedance of a PCB trace
- From: christopher.heard@xxxxxxxxxxxx
- To: doug@xxxxxxxxxx
- Date: Mon, 2 May 2005 14:58:24 -0400
Also, remember that surface microstrip traces get "plated up" to a thicker
value. Teradyne would assume that a 1oz. trace on the surface would get
plated up to 3.35mils thick and the top of the trapezoid would be 5.5 mils.
Chris
**********************
Chris Heard
Teradyne
Work: 603-879-1031
Cell: 508-277-5780
SMS Text Message: 5082775780@xxxxxxxxx
Email: christopher.heard@xxxxxxxxxxxx
AIM Screen Name: chrisheard2001
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| | Doug Brooks |
| | <doug@xxxxxxxxxx>|
| | Sent by: |
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| | 05/02/2005 02:29 |
| | PM |
| | Please respond to|
| | doug |
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| To: bill_hargin@xxxxxxxxxx, <GrahamDavies@xxxxxxxx>,
<si-list@xxxxxxxxxxxxx> |
| cc:
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| Subject: [SI-LIST] Re: Finding the impedance of a PCB trace
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>OK, looking at this more closely, I get
1. With Polar, no trace trapezoidal assumption (6 mil, 1 oz, rectangular)
Zo = 47.38
2. Polar, WITH trapezoidal assumption, 6 mil bottom, 5 mil top
Zo = 50.49
3. UltraCAD's UCCALC, automatically assumes a trapezoid, nominal 6 mil
bottom
Zo = 48.5
4. HyperLynx, assumes 6 mil x 1 oz rectangular
Zo = 47.6 (Bill, I don't know why you got a larger value!)
Doug Brooks
____________________________________________________________________________-
Check out UltraCAD's new presentation videos and new skin effect calculator
at http://www.ultracad.com
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