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>From willli Wed Jul 16 02:
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RE: Dielectric constant of FR4 - tempera
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Hi Walther,
Dk goes up by about 0.15 from 20 C to 120 C where my graph ends - so for 
example 4.8 becomes 4.95. This holds true between 1 MHz and 100 MHz - again 
I have no data beyond that.
If you go up to 150 C you are above Tg. I can only guess that there will be 
a change at Tg but how much and in which direction? This is not going to be 
a useful property as FR-4 is not stable long term at 150C.
Regards
Dave Heywood.
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From: [log in to unmask]
To: [log in to unmask]; Dave Heywood
Subject: Dielectric constant of FR4 - temperature
Date: 15 July 1997 22:26

<<File Attachment: ENVELOPE.TXT>>
I have a question regarding dielectric constant of FR4. How does Dk change
in case you increase the temperature from room temperature to maybe 150
degree C.
I remember I have seen once a curve somewhere, which showed  Dk increasing
drastically when the temperature went up.
Is this correct and what would be the explanation behind.

Walther

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