[SI-LIST] Re: Signal Integrity issues at -40 degrees C
- From: "Andrew Drysdale" <Andrew.Drysdale@xxxxxxxxxxxxxxxx>
- To: <jhill@xxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Mon, 12 Jun 2006 12:20:44 +0100
Hi John,
I have investigated the effects of temperature on Dk and Df. I also
found very little information on low temperature operation. However I
did find the following document useful.=20
http://www.dupont.com/thermount/pdf/comparison.pdf
From=20this I concluded that the variation of Dk is roughly linear and
used the data in this document to approximate the temperature
coefficient of FR4.
Best regards
Andy
=20
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Hill, John
Sent: 19 May 2006 15:07
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Signal Integrity issues at -40 degrees C
Hello,
We are starting a new design with 5 DDR2 memory busses and three
microprocessors. The design must work from -40 to +85 degrees C. I am
concerned that at low temperatures the edge rates will increase and I
don't know what will happen to the characteristic impedance of the
traces. I expect to have more issues with Signal Integrity issues at -40
than at 25 degrees C. Is this correct?
BTW, does anyone know the temperature coefficient of the Dielectric
Constant of various FR4 materials?=20
Best regards,
John
=20
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