[Fwd: [SI-LIST] : effect of trace width on the performance]

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From: Manoj F. Nachnani (manojn@hypersurf.com)
Date: Wed Nov 01 2000 - 06:38:02 PST


attached mail follows:


Muhammad:
The board with 9mm traces and 1oz copper on power plane has a lower
power plane inductance(hence lower Ldi/dt noise) and dc resistance than
the one with 0.5oz thick copper plane and that probably is why you see a
better performance.
Hope this helps.
Manoj N.

"Muhammad S. Sagarwala" wrote:

> Hi SI Gurus, I am in a big problem. I designed two boards which are
> pretty much the same.The changes between them are: (1) One has traces
> that are 7.5 mils wide and the other has 9 mils wide traces (both have
> a characteristic impedence of 50 ohms)(2) The one that has 9 mil wide
> traces has 1 oz copper for the pwr planes and the one with 7.5 mil
> wide traces has 0.5 oz. copper on pwr planes. The stackup is
> pretty much the same.The Frequency of signals on the boards is 400
> Mhz.The decoupling scheme on both boards is pretty much the same. The
> problems is the board with 9 mil wide traces and 1oz. copper is
> performing very good and the other board with 7.5 mil widetraces and
> 0.5 oz. copper is behaving very very bad. My question is "do you think
> these changes make a big difference or is there another variable(s)
> that I am missing?????" Comments suggestions are most welcome....(I
> need to be sure before I make a decision to respin the board
> ) Muhammad Muhammad S. Sagarwala
> Schlumberger SABER
> Ph. (408) 586 7065
> Fax (408) 586 4668

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