[SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect

From: Joel Brown <joel@xxxxxxxxxx>
To: dmarc-noreply@xxxxxxxxxxxxx
Date: Mon, 8 Dec 2014 10:37:59 -0800
We have recently started using some higher speed materials for 6 GBPS such
as Ventec VT-464L and Isola FR408HR but we have concerns such as cost, lead
time and CAF resistance more than fiber weave effect. Are there better
materials we should be considering? We will probably be getting into 8 GBPS
PCIe and 10G Ethernet soon.
Thanks

On Mon, Dec 8, 2014 at 10:26 AM, Dan Bostan <dmarc-noreply@xxxxxxxxxxxxx>
wrote:

> Yes, I agree. i used Megtron-6 successfully for signaling up to 31G. Love
> it.
>       From: Lee <leeritchey@xxxxxxxxxxxxx>
>  To: Romi Mayder <romi.mayder@xxxxxxxxxx>; 'Jonas Magnusson' <
> Jonas.Magnusson@xxxxxxxxxxxx>; scott@xxxxxxxxxxxxx; 'Carson Au' <
> carson.au@xxxxxxxxx>
> Cc: 'Ken Cantrell' <ken@xxxxxxxxxxxxxxxx>; "'Loyer, Jeff'" <
> jeff.loyer@xxxxxxxxx>; si-list@xxxxxxxxxxxxx
>  Sent: Sunday, December 7, 2014 1:58 PM
>  Subject: [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
>
> [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave EffectI stopped using
> spread 3313 because it is not all that well controlled with respect to
> spread.  Anyone who was at my 2103 DesignCon paper know what kind of nasty
> surprise we got when we used one version of it.
>
> From: Romi Mayder
> Sent: Sunday, December 07, 2014 12:06 PM
> To: mailto:leeritchey@xxxxxxxxxxxxx ; 'Jonas Magnusson' ; mailto:
> scott@xxxxxxxxxxxxx ; 'Carson Au'
> Cc: 'Ken Cantrell' ; 'Loyer, Jeff' ; mailto:si-list@xxxxxxxxxxxxx
> Subject: RE: [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
>
> The most common substrate we see for 28G backplanes is Megtron-6 NE glass
> using the 3313 spread glass weave. These are being used with our UltraScale
> 28G GTY FPGA backplane capable transceiver.
>
> As an example, for the FCI demo backplane featured on our Xilinx.com video
> with over 40 inches of trace (backplane plus 2 line cards with 3.5mm
> connects), we are seeing < 6 pS PN skew. Sample size is ~15.
>
> I hope this information is helpful.
>
>
>
> Kind Regards
> Romi
>
>
> -----Original Message-----
> From: Lee [leeritchey@xxxxxxxxxxxxx]
> Sent: Saturday, December 06, 2014 03:40 PM Pacific Standard Time
> To: Jonas Magnusson; scott@xxxxxxxxxxxxx; Carson Au
> Cc: Ken Cantrell; Loyer, Jeff; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
>
>
> I have tested GigaSync and Chronon from Isola.  Both of them produced very
> good results.  Maximum skew over 14" was 2 pSec.  Sample size 12.
>
> I'm not sure what Nelco, Panasonic and others are doing in  this area.
> Does
> anyone out there know?
>
> -----Original Message-----
> From: Jonas Magnusson
> Sent: Friday, December 05, 2014 7:14 PM
> To: leeritchey@xxxxxxxxxxxxx ; scott@xxxxxxxxxxxxx ; Carson Au
> Cc: Ken Cantrell ; Loyer, Jeff ; si-list@xxxxxxxxxxxxx
> Subject: RE: [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
>
> 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.
> KalkstensvÃ¤gen 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
> TeraspeedÃÂ® 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
> >> TeraspeedÃâÃÂ® 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
> >> > TeraspeedÃâÃÂ® 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, MarienwerderstraÃÆÃÂ¸e 3,
> >> > > D-32339 Espelkamp; Registergericht: Amtsgericht Bad Oeynhausen;
> >> Register-Nr.:
> >> > > HRB 8808; Vertretungsberechtigte GeschÃÆÃÂ¤ftsfÃÆÃÂ¼hrer: 
> >> > > Dipl.-Kfm.
> >> > > Edgar-Peter DÃÆÃÂ¼ning, Dipl.-Ing. Torsten Ratzmann,
> >> Dipl.-Wirtschaftsing.
> >> > > Ralf Martin Klein
> >> > >
> >> > > -----UrsprÃÆÃÂ¼ngliche 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 ÃÂ¢Ã¢âÂ¬ÃÂ¦
> >> > >
> >> > > IÃÂ¢Ã¢âÂ¬Ã¢âÂ¢m doing a bit of research on glass-weave skew / the
> >> > > fiber-weave
> >> effect.
> >> > > IÃÂ¢Ã¢âÂ¬Ã¢âÂ¢ve read the articles/presentations, and understand 
> >> > > the
> >> > > nature of the beast, but IÃÂ¢Ã¢âÂ¬Ã¢âÂ¢m interested in getting 
> >> > > data
> >> > > from the design
> >> trenches.
> >> > >
> >> > > Are you (or do you believe youÃÂ¢Ã¢âÂ¬Ã¢âÂ¢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 IÃÂ¢Ã¢âÂ¬Ã¢âÂ¢m going to hear in response, 
> >> > > but if
> >> > > you respond offline, IÃÂ¢Ã¢âÂ¬Ã¢âÂ¢ll hold the info you provide in
> >> > > confidence.
> >> > > If
> >> > > you reply publicly ÃÂ¢Ã¢âÂ¬Ã¢â¬Å I promise not to share your 
> >> > > secrets
> >> > > beyond the SI-List ÃÂ¢Ã¢âÂ¬ÃÂ¦
> >> > >
> >> > > Bill Hargin
> >> > > Director of North American Sales / Marketing Nan Ya Copper-Clad
> >> Laminates
> >> > > billh@xxxxxxxxxxxxx  ÃÂ¢Ã¢â¬âÃÂª  425-301-4425  ÃÂ¢Ã¢â¬âÃÂª  
> >> > > Skype:
> >> > > bill.hargin
> >> > >
> >> > >
> >> > >
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > -----------------------------------------------------------------
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References:
- [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
  - From: Lee
- [SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect
  - From: Dan Bostan
[SI-LIST] Re: AW: Glass-Weave Skew / Fiber-Weave Effect

Other related posts:
