[SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
- From: Jonas Magnusson <Jonas.Magnusson@xxxxxxxxxxxx>
- To: "leeritchey@xxxxxxxxxxxxx" <leeritchey@xxxxxxxxxxxxx>, "scott@xxxxxxxxxxxxx" <scott@xxxxxxxxxxxxx>, Carson Au <carson.au@xxxxxxxxx>
- Date: Sat, 6 Dec 2014 03:14:29 +0000
Gurus, what is your thoughts on the Isola Gigasync mtrl?
Cheers,
--
Jonas Magnusson
Senior Hardware Designer
Teamleader Hardware design
Synopsys Hardware Platforms Group
Synopsys, Inc.
Kalkstensvägen 3
SE-224 57 LUND
SWEDEN
Phone : +46-46-16 29 05
Fax : +46-46-16 29 01
Cell : +46-70-89 89 774
E-mail : jonasm@xxxxxxxxxxxx
Web : www.synopsys.com
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Lee
Sent: den 5 december 2014 17:18
To: scott@xxxxxxxxxxxxx; Carson Au
Cc: Ken Cantrell; Loyer, Jeff; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
AH! The gods again!
-----Original Message-----
From: Scott McMorrow
Sent: Friday, December 05, 2014 2:50 PM
To: Carson Au
Cc: Ken Cantrell ; Loyer, Jeff ; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
One must be patient and wait for the gods to reveal such a material.
Release is imminent.
Scott McMorrow
Teraspeed® Consulting - A Division of Samtec
16 Stormy Brook Rd
Falmouth, ME 04105
(401) 284-1827 Business
http://www.teraspeed.com
On Fri, Dec 5, 2014 at 5:41 PM, Carson Au <carson.au@xxxxxxxxx> wrote:
> What are these spread-independent materials? I only know of Isola's
> Gigasync.
>
> On Sat, Dec 6, 2014 at 9:28 AM, Ken Cantrell <ken@xxxxxxxxxxxxxxxx> wrote:
>
>> Jeff,
>> Give him the money!! :)
>>
>> Ken
>>
>> -----Original Message-----
>> From: si-list-bounce@xxxxxxxxxxxxx
>> [mailto:si-list-bounce@xxxxxxxxxxxxx]
>> On Behalf Of Scott McMorrow
>> Sent: Friday, December 05, 2014 3:00 PM
>> To: Loyer, Jeff
>> Cc: si-list@xxxxxxxxxxxxx
>> Subject: [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
>>
>> Jeff
>> on the shining the light thing, that's called an optical densitometer.
>> you can make one with a calibrated flatbed scanner. Then it's a
>> matter of creating a table of optical density vs Er. It would make
>> for a nice academic study.
>>
>> As for the dozens of materials I've characterized recently, I can
>> tell you that I have a method that provides a very accurate relative
>> figure of merit between weave/resin systems in one trace measurement
>> per laminate stackup, not accounting for non-orthogonality of board
>> and weave. A few more traces and I can adjust for weave/board misalignment.
>>
>> As for something that gives statistically accurate skew spread
>> measurements ... nope. Care to fund the study? I know how to do it.
>> Have
>> known for 10 years I know the quickest methodology to get the
>> statistical results. It's just a matter of sampling quite a few
>> boards.
>>
>>
>> Scott McMorrow
>> Teraspeed® Consulting - A Division of Samtec
>> 16 Stormy Brook Rd
>> Falmouth, ME 04105
>> (401) 284-1827 Business
>> http://www.teraspeed.com
>>
>> On Fri, Dec 5, 2014 at 4:39 PM, Loyer, Jeff <jeff.loyer@xxxxxxxxx> wrote:
>>
>> > Hi Scott,
>> > Can you share any of the studies you've performed to characterize
>> > the dozens of materials? I'm especially interested in clever
>> > techniques you might have used to ensure you measured the maximum
>> > for each material, given the statistical nature of the problem
>> > (whenever I think of performing such a study, I am put off by "how
>> > do I ensure my data includes some representative 'worst case'?").
>> >
>> > To all,
>> > I believe there is extreme ambiguity in the terms used for spread
>> > glass, I would be wary of any particular terminology (is "ultra"
>> > better than "hyper"?). And, even if you do standardize the
>> > definition of "spread", the net effect is going to vary
>> > significantly for the various glass styles
>> > (1080 will probably always be more problematic than 2116, for
>> > instance). I don't know of any method of easily quantifying the
>> > electrical properties of any particular spread glass. There is
>> > work on-going for a visible light test, but as far as I know those
>> > results have not yet been correlated to Vp differences.
>> > BTW, this might be a nice opportunity for a clever person to come
>> > up with an easy (cheap, HVM-compatible) method of shining a light
>> > through glass weaves and quantifying the difference between the
>> > brightest and darkest areas - ideal "spread glass" would have very
>> > little difference, corresponding to very little difference in Vp
>> > across the
>> weave.
>> > And finally, I don't know of any silicon solutions, ours or
>> > otherwise, used explicitly to solve the fiberweave issue. Adaptive
>> > equalization may make it less of an issue than it was previously, however.
>> >
>> > Jeff Loyer
>> >
>> >
>> > -----Original Message-----
>> > From: si-list-bounce@xxxxxxxxxxxxx
>> > [mailto:si-list-bounce@xxxxxxxxxxxxx]
>> > On Behalf Of Scott McMorrow
>> > Sent: Friday, December 05, 2014 5:42 AM
>> > To: Havermann, Gert
>> > Cc: billh@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
>> > Subject: [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
>> >
>> > Gert,
>> > Even flat weaves have skew, as easily evidenced by a picture of the
>> > weave that shows gaps in the overlap of fiber bundles in one direction.
>> >
>> > I've found that the killer problem is skew on line cards causing
>> > diff to common mode conversion that bursts as crosstalk within
>> > connector PTH via fields and connectors themselves, which are not
>> > designed to control common modes. This was seen specifically in a
>> > significant loss of NEXT margin at receivers from Tx or Rx card
>> > skew causing excessive crosstalk in the connector pin fields for a
>> > well-known standard. This required two solutions, one was to
>> > guardband margin to allow for the additional skew caused NEXT. The
>> > other was to use some
>> skew abatement methods.
>> >
>> > Doing 1000's of sensitivity runs I've found that this skew
>> > sensitivity is much worse on cards than it is on backplanes. That
>> > is, the card skew allowance has much less tolerance than does the
>> > backplane or total end-to-end skew. Where the skew is located is
>> > much more important than how much skew there is.
>> >
>> > To put some numbers to this phenomena, a 10G link had 12 ps of
>> > skew, which translates to around -0.7 dB of additional insertion
>> > loss. That is generally not a serious issue for 99.9% of all
>> > designs. However when the effective loss due to crosstalk was
>> > factored in, due to diff to common mode and common mode to diff
>> > conversion, total additional eye
>> loss was -3.9 dB.
>> > which is a huge impairment.
>> >
>> > In the end, the only solution for skew, especially at 28G rates and
>> > above, is to utilize special techniques to mitigate skew on
>> > backplanes, and skew-free materials on cards. I've measured and
>> > characterized dozens of materials and can say that I can easily
>> > demonstrate the potential for any woven PCB laminate to have
>> > significant skew, even those with spread weaves, except for those
>> > laminates that are specifically engineered for zero-skew with
>> > matched
>> glass and resin dielectric constants.
>> >
>> > Regards,
>> >
>> > Scott
>> >
>> > Scott McMorrow
>> > Teraspeed® Consulting - A Division of Samtec
>> > 16 Stormy Brook Rd
>> > Falmouth, ME 04105
>> > (401) 284-1827 Business
>> > http://www.teraspeed.com
>> >
>> > On Fri, Dec 5, 2014 at 3:29 AM, Havermann, Gert <
>> > Gert.Havermann@xxxxxxxxxxx>
>> > wrote:
>> >
>> > > Hi Bill,
>> > > I've seen it quite often, but I never seen it killing System
>> > > performance as we work with good margin, and the Silicon accepts
>> > > even more skew that expected.
>> > > One Design was not usable due to weave effect skew. It was a TRL
>> > > Cal.Stucture where the shortest line hat skew exceeding the Phase
>> > > difference. After that I redesigned with different Material and
>> > > flat weave Glass, and that worked great.
>> > >
>> > > BR
>> > > Gert
>> > >
>> > >
>> > > ----------------------------------------
>> > > Absender ist HARTING Electronics GmbH, Marienwerderstraße 3,
>> > > D-32339 Espelkamp; Registergericht: Amtsgericht Bad Oeynhausen;
>> Register-Nr.:
>> > > HRB 8808; Vertretungsberechtigte Geschäftsführer: Dipl.-Kfm.
>> > > Edgar-Peter Düning, Dipl.-Ing. Torsten Ratzmann,
>> Dipl.-Wirtschaftsing.
>> > > Ralf Martin Klein
>> > >
>> > > -----Ursprüngliche Nachricht-----
>> > > Von: si-list-bounce@xxxxxxxxxxxxx
>> > > [mailto:si-list-bounce@xxxxxxxxxxxxx]
>> > > Im Auftrag von Bill Hargin (Nan Ya, USA)
>> > > Gesendet: Freitag, 5. Dezember 2014 06:04
>> > > An: si-list@xxxxxxxxxxxxx
>> > > Betreff: [SI-LIST] Glass-Weave Skew / Fiber-Weave Effect
>> > >
>> > > Hi Folks …
>> > >
>> > > I’m doing a bit of research on glass-weave skew / the
>> > > fiber-weave
>> effect.
>> > > I’ve read the articles/presentations, and understand the
>> > > nature of the beast, but I’m interested in getting data
>> > > from the design
>> trenches.
>> > >
>> > > Are you (or do you believe you’ve) seen it in your designs?
>> > > What
>> > > happened, and how did you resolve it? (E.g., angled routing,
>> > > low-Dk glass, homogeneous resin/glass, etc.) What were the
>> > > characteristics of the material and signals?
>> > >
>> > > I have no idea what I’m going to hear in response, but if
>> > > you respond offline, I’ll hold the info you provide in confidence.
>> > > If
>> > > you reply publicly – I promise not to share your secrets
>> > > beyond the SI-List …
>> > >
>> > > Bill Hargin
>> > > Director of North American Sales / Marketing Nan Ya Copper-Clad
>> Laminates
>> > > billh@xxxxxxxxxxxxx â–ª 425-301-4425 â–ª Skype:
>> > > bill.hargin
>> > >
>> > >
>> > >
>> > >
>> > >
>> > >
>> > >
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>
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