[SI-LIST] Re: fiber-weave effect alive and well?
- From: "HINTON,MARK" <mark.hinton@xxxxxxxxxxxxx>
- To: <leeritchey@xxxxxxxxxxxxx>
- Date: Fri, 30 Nov 2007 14:48:22 -0800
Lee,
Have you tested 2116 glass yet? I'm doing a low-volume test PCB, and I
may have to choose between 2116 or a high-cost special order of 3113.
If you haven't tested it yet, would you venture an educated guess on how
it would perform? I've got pretty wide traces (9.5 mils).
Thank you,
Mark
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Lee Ritchey
Sent: Saturday, September 15, 2007 11:23 AM
To: Scott McMorrow; Perry.Qu@xxxxxxxxxxxxxxxxxx
Cc: si-list
Subject: [SI-LIST] Re: fiber-weave effect alive and well?
The weave I document is 3313 glass. It is widely used in Asia and is a
stock weave from Isola. We just completed testing on 2113 weave and
obtained similar results. The two thin weaves that are at the root of
the
problem are 106 and 1080. 3313 has not been widely used by US
fabricators,
I suspect because designers have been asking for the thinnest possible
laminates and that is why 1080 and 106 are used most often in the US.
You
don't get 3313 and 2113 here unless you stick to your guns and insist on
it. When you do, there are no real problems.
We've just completed testing two designs with 48 ports of 10 GE with
superb
results. One used 2113 and the other 3313.
7628 is about as coarse as the cloth used to make levis. Not a good
choice.
Lee
> [Original Message]
> From: Scott McMorrow <scott@xxxxxxxxxxxxx>
> To: <Perry.Qu@xxxxxxxxxxxxxxxxxx>
> Cc: si-list <si-list@xxxxxxxxxxxxx>
> Date: 9/14/2007 1:21:15 PM
> Subject: [SI-LIST] Re: fiber-weave effect alive and well?
>
> Perry
> Fiber-weave effects are alive and well, and IMO should be considered
by=20
> every designer concerned with 6 Gbps or higher differential serial
data=20
> communications channels on PCBs, backplanes, and single-ended skew=20
> controlled parallel buses. Jeff's paper is real life, building upon=20
> about 5 years of good research at Intel. The method that is used is=20
> quite valid and will be seen in real designs. The Intel research is=20
> able to better characterize weave skew using physical nyquist sampling
> techniques. Yes, with different trace jogs you will see all sorts of=20
> potential alignments, but in the worst case you will still find that=20
> traces can have significant lengths of worst case fiber weave=20
> alignment. If you are trying to design systems with 1000's of=20
> differential pairs, there is a statistical certainty that one or more
of=20
> those pairs will have skew close to the absolute worst case, if not=20
> designed to compensate for laminate weave anisotropy.
>
> The problem is most pronounced with weaves that have large holes
without=20
> fiber in the weave pattern, but you will also see issues with core=20
> materials that are often constructed with large diameter fibers, like=20
> 7628 material. The fiberglass the Lee proposes to use does have some=20
> benefits, however, it does not totally eliminate the fiber weave=20
> problem. It reduces it to a lower level. Unfortunately, it is not a=20
> widely manufactured laminate weave.
>
> There are patented techniques for improving weave-induced skew, which=20
> must be licensed. There are also some non-patented techniques, which=20
> may also be used that are not quite as effective as the patented=20
> techniques, but nevertheless can be used to design robust systems. =20
> There is also some silicon IP that can be used to automatically=20
> compensate for skew, and is finding it's way into test
instrumentation.
>
>
> regards,
>
> 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
>
>
>
> QU Perry wrote:
> > 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
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 parallel
with
> > edge. The "jog" as is called in the paper is very common due to vias
etc
> > and pretty random.
> >
> > Also from the data we got from PCB vendor, it appears that thinner
> > dielectric substrate the worse fibre weave effect as the gap between
the
> > fiber is larger. Has this been looked at ?
> >
> > Regards
> >
> > Perry
> >
> >
=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
> > =
=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
> >
> >
=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
> > =
=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
> >> [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of=3D20
> >> Aubrey_Sparkman@xxxxxxxx
> >> Sent: Friday, September 14, 2007 1:59 PM
> >> To: leeritchey@xxxxxxxxxxxxx; rdudek@xxxxxxxxxxxxxxx;=3D20
> >> 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
> >> Enterprise Engineering Signal Integrity Team=3D3D20 Dell,
Inc.=3D3D20=3D20
> >> Aubrey_Sparkman@xxxxxxxx=3D3D20
> >> (512) 723-3592=3D3D20
> >> "Discovery consists of seeing what everybody has seen and=3D20
> >> thinking what nobody else has thought." - Jonathan Swift
> >> =3D20
> >> =3D20
> >> -----Original Message-----
> >> From: si-list-bounce@xxxxxxxxxxxxx=3D20
> >> [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 April issue of Circuitree magazine.
> >> =3D20
> >> Lee Ritchey
> >> =3D20
> >> =3D20
> >> =20
> >>> [Original Message]
> >>> From: Russell S. Dudek Jr. <rdudek@xxxxxxxxxxxxxxx>
> >>> To: <si-list@xxxxxxxxxxxxx>
> >>> 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
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
the=3D20
> >>> specifics of=3D3D20 the technology and our partners in such =
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 <http://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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