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From [log in to unmask] Thu Sep 5 08: |
33:25 1996 |
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I have seen data to suggest the difference between 1 Mhz to 1 Ghz
is ~10%. Like standard FR-4 is ~4.5 @ 1 Mhz and ~4.1 @ 1 Ghz. I
haven't seen values at 2 Ghz. Some materials have a flatter response
across a larger (BW) range of frequencies. This means that they have
less electrical performance variation(degradation) from say 1 Mhz to 1
Ghz. Some of these materials are Getek, BT, Cyanate Ester, and
alternative glass fiber styles (random aramids). Remember there is a
cost associated with the higher performance materials.
One thing I do know is that not all material manufacturers have ran
these Er tests at different frequencies. The exotic material suppliers
have, but not all the standard FR-4 makers. We (fabricators) have
constantly been asked this question by our customers and have
requested this type of testing from our material suppliers. Few have
responded. In order for their materials to even be considered for an
RF design they need to at least do their homework. The other materials
provide a "slight edge" electrical performance wise and those
suppliers have targeted this market with their Er and Df results at
various frequencies (as you've requested). Wake up call!
Groovy
______________________________ Reply Separator _________________________________
Subject: Fabrication
Author: [log in to unmask] at SMTPLINK-HADCO
Date: 9/4/96 6:05 PM
From: Scott B. Westheimer
Date: September 5,1996
I am looking for information about the Dk of material measured at 1 mhrtz
and measured at 1 and 2 ghrtz. What would be the expected change? Does
anyone have an article that they could send me are direct me too? Are any
of you PCB end users requiring that boards be measured at 1 to 2 ghrtz?
Thanks
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