[SI-LIST] Re: FR4 Permittivity
- From: Ray Anderson <ray.anderson@xxxxxxxxxx>
- To: "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
- Date: Thu, 21 Feb 2013 17:17:13 +0000
From the Isola 370HR data sheet:
Freq. Test Method Er
100 MHz (HP4285A) 4.24
1 GHz (HP4291A) 4.17
2 GHz (Bereskin Stripline) 4.04
5 GHz (Bereskin Stripline) 3.92
10 GHz (Bereskin Stripline) 3.92
-Ray
Raymond Anderson
Senior Signal Integrity Staff Engineer
Programmable Platforms Development
Silicon Technology Group
Signal Integrity and Package Development Department
Xilinx Inc.
2100 Logic Drive
San Jose, California 95124
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Havermann, Gert
Sent: Thursday, February 21, 2013 5:16 AM
To: cyril.chastang@xxxxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] AW: FR4 Permittivity
This isn't good data.
First of all, they only tested only once (you can tell that there is no
variation in their Test results).
Second, they don't specify the test Method they used, and there are official
test methods giving totally wrong results (the old 1MHz plate capacitor method
@ 1MHz used to be quite inaccurate).
Third, the Data is measured at 1MHz, thus these values are useless for speeds
exceeding 100MHz
I recommend to go by the Datasheet (Isola is usually very good at dk/df
testing), or test it on your own, but 2.173 is physically impossible for glass
reinforced resin as the glass altready has a much higher dk.
BR
Gert
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