[SI-LIST] Re: Dielectric constant measuring
- From: "Juergen Flamm" <jflamm@xxxxxxxxxxx>
- To: <sitaskina@xxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Tue, 23 Oct 2007 12:35:50 -0700
Could it be you are using a micro strip test object? If so the result is
probably correct, as you are measuring the effective dielectric constant
(combination of dielectric materials of the board and air).
=20
Best Regards - Juergen
=20
Juergen Flamm, Dipl. Ing. / C.I.D.
Core Comp AE SPB, Cadence Design Systems, Inc. - Irvine, CA
Phone: 818-642-6255 E-mail: jflamm@xxxxxxxxxxx
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of ma mu
Sent: Tuesday, October 23, 2007 11:39 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Dielectric constant measuring=20
Hi ,
=20
I am trying to measure the dielectric constant value of our ckt at
100mhz -3 Ghz in our lab. I have measured it but the value is too low
2.5 ( expectiing value is between 3.2 to 3.5) .
=20
I have used Iconnect software to measure the transient time for an
electromagnetc pulse to travel the length of my transmission line.
=20
and the formula I have used is following:
td=3Dmeasured data
l=3Dlength of the transmission line
Vc=3D velocity of light.=20
=20
Er=3D (Vc*Vc*td*td)(l*l)
=20
the TDR I have used has 35 ps rise time .=20
=20
=20
please let me know why I did get this low value. or you could
recommend me to find a way to get Er value. I will appreciate your help.
=20
=20
Ma
Steve,
Thanks for the plug! Sometimes the best solutions are the easiest!
Lee
> [Original Message]
> From: steve weir
> To:=20
> Cc: QU Perry
; si-list
> Date: 9/15/2007 12:10:47 PM
> Subject: Re: [SI-LIST] Re: fiber-weave effect alive and well?
>
> In the shameless plug for someone else dept: Lee's book "Right the=20
> First Time Volume 2" does do a nice job of demonstrating the=20
> difference between various weaves including some good cross-section=20
> microphotographs and TDR plots. I think it is worth the price of the=20
> book for that information alone.
>
> Steve
> Lee Ritchey wrote:
> > The link to the Circuitree web site requires each person to register
> > and obtain a password.
> >
> > It is true that the thinner weaves are the problem.
> >
> > I cover these weaves and results in Chapter 5 of Volume 2 of my
book.=20
> > There are photos showing what the weaves look like compared to a 3.5
mil
> > trace. Also show what vias do to very fast signals.
> >
> > Lee Ritchey
> >
> >
> >=20
> >> [Original Message]
> >> From: QU Perry
> >> To: si-list
> >> Date: 9/14/2007 12:25:54 PM
> >> Subject: [SI-LIST] Re: fiber-weave effect alive and well?
> >>
> >> I would be interested to see a link as well.
> >>
> >> Jeff's paper on DesignCon2007 is convincing to me that this is
something
> >> we need to pay attention. Real life design will probably not be as=20
> >> bad as the theoretical estimate since most of the diff pair routing
> >> we have on the PCB is not likely to run a long length non-stop in=20
> >> parallel with edge. The "jog" as is called in the paper is very=20
> >> common due to vias
etc
> >> and pretty random.
> >>
> >> Also from the data we got from PCB vendor, it appears that thinner=20
> >> dielectric substrate the worse fibre weave effect as the gap=20
> >> between
the
> >> fiber is larger. Has this been looked at ?
> >>
> >> Regards
> >>
> >> Perry
> >>
> >>
> >>=20
> >
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D=
3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D
=3D3D=3D
> >=20
> >> =
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D=
20
> >>
> >> Perry Qu=3D20
> >>
> >> Design & Qualification, Alcatel-Lucent Canada Inc.
> >>
> >> 600 March Road, Ottawa ON, K2K 2E6, Canada=3D20
> >>
> >> DID: 613-7846720 Fax: 613-5993642=3D20
> >>
> >> Email: perry.qu@xxxxxxxxxxxxxxxxxx=3D20
> >>
> >>
> >>=20
> >
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D=
3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D
=3D3D=3D
> >=20
> >> =
=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D3D=3D=
20
> >>
> >> =3D20
> >>
> >>=20
> >>> -----Original Message-----
> >>> From: si-list-bounce@xxxxxxxxxxxxx=3D20=20
> >>> [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of=3D20=20
> >>> Aubrey_Sparkman@xxxxxxxx
> >>> Sent: Friday, September 14, 2007 1:59 PM
> >>> To: leeritchey@xxxxxxxxxxxxx; rdudek@xxxxxxxxxxxxxxx;=3D20=20
> >>> si-list@xxxxxxxxxxxxx
> >>> Subject: [SI-LIST] Re: fiber-weave effect alive and well?
> >>> =3D20
> >>> Would you like to share a link?=3D3D20 =3D20 =3D20 Aubrey =
Sparkman=3D3D20=20
> >>> Enterprise Engineering Signal Integrity Team=3D3D20 Dell,=20
> >>> Inc.=3D3D20=3D20 Aubrey_Sparkman@xxxxxxxx=3D3D20
> >>> (512) 723-3592=3D3D20
> >>> "Discovery consists of seeing what everybody has seen and=3D20=20
> >>> thinking what nobody else has thought." - Jonathan Swift =3D20 =
=3D20=20
> >>> -----Original Message-----
> >>> From: si-list-bounce@xxxxxxxxxxxxx=3D20=20
> >>> [mailto:si-list-bounce@xxxxxxxxxxxxx]
> >>> On Behalf Of Lee Ritchey
> >>> Sent: Friday, September 14, 2007 11:36 AM
> >>> To: Russell S. Dudek Jr.; si-list@xxxxxxxxxxxxx
> >>> Subject: [SI-LIST] Re: fiber-weave effect alive and well?
> >>> =3D20
> >>> We already have a glass weave solution. Check my column in=3D20 =
the=20
> >>> April issue of Circuitree magazine.
> >>> =3D20
> >>> Lee Ritchey
> >>> =3D20
> >>> =3D20
> >>>=20
> >>>> [Original Message]
> >>>> From: Russell S. Dudek Jr.=20
> >>>> To:=20
> >>>> Date: 9/12/2007 1:10:28 PM
> >>>> Subject: [SI-LIST] Re: fiber-weave effect alive and well?
> >>>>
> >>>> Steve,
> >>>> =3D3D20
> >>>> I agree, Fiber Weave Effect (FEW) has most certainly been=3D20
> >>>>=20
> >>> confirmed by
> >>> such
> >>>=20
> >>>> research. However, there is a new change in the wind. I=3D20
> >>>>=20
> >>> have the=3D3D20=3D20
> >>>=20
> >>>> unique opportunity, as a technical liaison, to enable a=3D20
> >>>>=20
> >>> technology=3D3D20=3D20
> >>>=20
> >>>> that may put
> >>>>=20
> >>> an
> >>>=20
> >>>> end to FWE as a consideration in high-speed designs. We=3D20
> >>>>=20
> >>> all know that
> >>> =3D20
> >>>=20
> >>>> the crux of the matter is the glass weave and its effect on=3D20
> >>>>=20
> >>> localized
> >>> Er.
> >>>=20
> >>>> Either get ride of the reinforcement layer completely or=20
> >>>> more=3D3D20=3D20 challenging change the fundamentals of the glass =
> >>>> weave fabrication
> >>>>=20
> >>> process (GWFP).
> >>>=20
> >>>> =3D3D20
> >>>> We have taken the more challenging (and fun) approach and =
have=3D20
> >>>> rocked=3D3D20 the fundamentals the GWFP. I cannot disclose much=20
> >>>> the=3D20 specifics of=3D3D20 the technology and our partners in =
such=20
> >>>> an=3D20
> >>>>=20
> >>> open forum. =3D20
> >>>=20
> >>>> However, if=3D3D20 you are interested learning more feel =
free=3D20
> >>>>=20
> >>> to contact=3D20
> >>>=20
> >>>> me and we can=3D3D20 get the proper NDAs in place to =
facilitate=3D20
> >>>>=20
> >>> such a discussion.
> >>>=20
> >>>> =3D3D20
> >>>> RD
> >>>> =3D3D20
> >>>> Russell Dudek
> >>>> Technology Specialist
> >>>> Compunetics, Inc.
> >>>> 700 Seco Road
> >>>> Monroeville, PA 15146
> >>>> 412-858-6264
> >>>> rdudek@xxxxxxxxxxxxxxx
> >>>> www.compunetics.com =3D3D20
> >>>>
> >>>> To see where no one notices the contrast of white on white is =3D
> >>>>=20
> >> an=3D3D20=3D20
> >>=20
> >>>> indispensable virtue of infinite potential.
> >>>>
> >>>> =3D3D20
> >>>>
> >>>>
> >>>>
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> --
> Steve Weir
> Teraspeed Consulting Group LLC
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