[SI-LIST] Re: Skin Effect, Au, and Cu

From: "Cortex Chen" <Cortex.Chen@xxxxxxxxxxxx>
To: "richard moffat" <richard.moffat@xxxxxxxxxxxxxxxxxxx>, <Aubrey_Sparkman@xxxxxxxx>, <AmateurND@xxxxxxx>
Date: Tue, 22 Feb 2005 09:39:40 +0800
Dear All,

If you remember that the dielectric loss is proportional to frequency =
and conductor loss is proportional to square root of frequency,
then dielectric loss is significant than conductor loss at GHz level.

I also agree that Aubrey's speaking that Richard needs to look further =
for loss due to soldermask.

Regards,

Cortex

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of
Aubrey_Sparkman@xxxxxxxx
Sent: Tuesday, February 22, 2005 6:40 AM
To: AmateurND@xxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Skin Effect, Au, and Cu


On re-reading the original question, I might not has answered the
intended question.  I addressed the quote in the email:  "At high enough
frequencies (we do 18 GHZ on rogers) the soldermask changes the
impedance of the line." Soldermask does impact CHARACTERISTIC impedance,
especially on tightly coupled differential pairs.

After the quote above, the question that was asked but not answered by
me was: "Is the loss due to the soldermask coating greater than the skin
effect loss at very high frequencies?"  It was not my intent to comment
on whether Soldermask coating caused more loss than skin effect loss at
any frequency.  My apologies for any confusion.

While the paper quoted below is a very good paper on conductor loss, I
think Richard needs to look further for loss due to soldermask.

Aubrey Sparkman=3D20
Enterprise Engineering Signal Integrity Team
Dell, Inc.=3D20
Aubrey_Sparkman@xxxxxxxx=3D20
(512) 723-3592

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of AmateurND@xxxxxxx
Sent: Monday, February 21, 2005 3:59 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Skin Effect, Au, and Cu

=3D20
Good day.  There is a paper written by James Rautio (Sonnet Software)
that might provide some answers.  "An Investigation of Microstrip
Conductor  Loss." =3D20
It can be downloaded at
_http://www.sonnetusa.com/support/publications.asp_
(http://www.sonnetusa.com/support/publications.asp)=3D20
=3D20
Michael
=3D20
=3D20
In a message dated 2/21/05 2:34:36 PM Central Standard Time,
Aubrey_Sparkman@xxxxxxxx writes:
Soldermask changes the impedance (especially tightly coupled diff  pair)
for lower frequencies too, just not as significant at low  impedance
single ended traces.

It's less of a series (skin effect)  phenomena; did you remember to
consider the impact of dielectric constant  on impedance....

Aubrey Sparkman=3D3D20
Enterprise Engineering Signal  Integrity Team Dell, Inc.=3D3D20
Aubrey_Sparkman@xxxxxxxx=3D3D20
(512)  723-3592






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[SI-LIST] Re: Skin Effect, Au, and Cu

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