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Message
From: jazimme2@y...
Date: Tue, 13 May 2003 23:59:38 -0100
Subject: Re: [pci] ucf file
This is veering offtopic, but I think a correction is in order because the I
don't think the original poster was cc'd on the response:
Foot in mouth. That's what comes from giving a pat answer like I did,
not having time to think it over. Sorry. Read on...
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>From Mike Dini:
All of our stuff does this. You only need two layers to do PCI with a
1mm BGA. You generally need a 4 4 trace width board.
Also, the app note, 157, isn't entirely correct. It is not as aggressive as
possible.
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While I agree in theory, my response to this would be 4/4 boards are
more expensive, and a good many prototype places I've seen do not
support less than 5/5 (Advanced Circuits for one). Of course, you could
always pay a little more, get more boards, and go to production-level
specs. Also, Mike, when you say two layers, do you mean two *signal*
layers? That would be a 4-layer board counting power and ground
planes. So I guess my answer would be yes, you could do it with two
signal layers if either you leave some pins unconnected or use a finer
geometry.
j.
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