FreeLists / si-list / [SI-LIST] Re: Er range of FR4

["Zanella, Fabrizio" <fzanella@xxxxxxxxxxxxx>]

Aubrey, Charles, for correct calculation of impedance with 2D field
solvers, I use a dielectric constant of 3.8-4.0 for FR4, depending on
the laminate thickness.  I've found this range of values to match
impedance measurements and calculations by board vendors.

Fabrizio Zanella

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Aubrey_Sparkman@xxxxxxxx
Sent: Tuesday, August 02, 2005 2:48 PM
To: scott@xxxxxxxxxxxxx; Charles.Grasso@xxxxxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Er range of FR4

When I just care about min and max flight times I have been using 3.5 to
4.5.  But I know there are some materials with vendor data at 4.6 or
more.

I would also like to know what others are using.=3D20


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 Scott McMorrow
Sent: Tuesday, August 02, 2005 1:36 PM
To: Charles.Grasso@xxxxxxxxxxxx
Cc: 'si-list@xxxxxxxxxxxxx'
Subject: [SI-LIST] Re: Er range of FR4

Charles,

It depends upon the stackup used.  I would suggest that you go to the
Park Nelco website and signup for their dielectric calculator. It is
very useful for calculating the average Er for any particular laminate
lay up.  Beyond that, localized Er variations are bounded by the Er of
epoxy and glass  (3.2 and 5.6 by weight, respectively.)

scott

Scott McMorrow
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
(401) 284-1827 Business
(401) 284-1840 Fax

http://www.teraspeed.com

Teraspeed(r) is the registered service mark of Teraspeed Consulting
Group LLC



Grasso, Charles wrote:

>Hi - What is the industry accepted range of FR4?
>I have been using 3.5 - 5. Does that seem correct?
>
>=3D20
>
>Best Regards
>Charles Grasso
>Senior Compliance Engineer
>Echostar Communications Corp.
>Tel: 303-706-5467
>Fax: 303-799-6222
>Cell: 303-204-2974
>Pager/Short Message: 3032042974@xxxxxxxx <mailto:3032042974@xxxxxxxx>
>Email: charles.grasso@xxxxxxxxxxxx;
>Email Alternate: chasgrasso@xxxxxxxx
>
>=3D20
>
>
>
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