[SI-LIST] Re: AW: fiber weave effect
- From: "Lee " <leeritchey@xxxxxxxxxxxxx>
- To: <kelvin.harding@xxxxxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Fri, 15 Aug 2014 15:33:28 -0700
This is one of those Einstein things, where "everything should be as simple
as possible and no simpler". if you need the layers to meet your SI goals
and at the same time make a design manufacturable, you add the layers and
get on with it.
-----Original Message-----
From: kelvin.harding@xxxxxxxxxxxxxxx
Sent: Friday, August 15, 2014 3:12 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: AW: fiber weave effect
Hi Lee,
How would you tackle a large FPGA on a small PCB with more than 140 diff
pairs.
If there is not enough room to split the pair to route between BGA
pads/vias and not enough board area for loosely coupled pairs what are
the options?
Regards,
Kelvin
On 2014-08-15 21:58, Lee wrote:
> Ken,
>
> What do you mean by elaborate?
>
> -----Original Message-----
> From: Ken Cantrell
> Sent: Friday, August 15, 2014 12:44 PM
> To: leeritchey@xxxxxxxxxxxxx ; shlepnev@xxxxxxxxxxxxx ;
> jeff.loyer@xxxxxxxxx
> ; Gert.Havermann@xxxxxxxxxxx ; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: AW: fiber weave effect
>
> Lee,
> Would you like to elaborate on your "for the record" statement?
>
> Thanks,
>
> Ken
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx] On
> Behalf Of Lee
> Sent: Friday, August 15, 2014 11:38 AM
> To: shlepnev@xxxxxxxxxxxxx; jeff.loyer@xxxxxxxxx;
> Gert.Havermann@xxxxxxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: AW: fiber weave effect
>
> Ah! Since then we have built several more test PCBs using other glass
> styles with great results. The DesignCon 2013 paper was the stimulus
> for
> building more test PCBs including some using GigaSync with results
> similar
> to yours. We are about to build several more.
>
> What we learned with the DesignCon paper is that there are two
> different
> versions of 3313 weave, one that is mechanically spread in both
> directions
> and one that is mechanically spread in only one direction- the weave
> used in
> the DesignCon paper. You can see that skew in on axis is very good and
> in
> the other it is poor.
>
> Out of this has grown a movement to define what mechanically spread
> means.
> We are a long way from getting this one settled.
>
> For the record, I never use tightly coupled traces. There are too many
> down
> sides and very few up sides.
>
> -----Original Message-----
> From: Yuriy Shlepnev
> Sent: Friday, August 15, 2014 10:06 AM
> To: 'Lee ' ; jeff.loyer@xxxxxxxxx ; Gert.Havermann@xxxxxxxxxxx ;
> si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: AW: fiber weave effect
>
> Hi Lee,
>
> For the test boards (there were a few) we used Isola's I-SPEED with
> 3313
> glass on one side. As follows from your DesignCon 2013 paper, you
> observed
> 59 ps maximal skew for 14' horizontally oriented lines (table on page
> 10)
> for that specific case - did I miss something?
> Isola's GigaSync on 2116 glass was used on the other side of the board.
> There were no measurable differences in the skew for the tightly
> coupled
> traces between two materials. The skew was actually too small to make
> any
> conclusions in both cases. However, GigaSync produced smaller far-end
> mode
> transformation, that looks like much better metric for the material
> inhomogeneity, comparing to the direct skew comparison (especially for
> the
> tightly coupled traces).
>
> Best regards,
> Yuriy
>
> Yuriy Shlepnev, Ph.D.
> President, Simberian Inc.
> 3030 S Torrey Pines Dr. Las Vegas, NV 89146, USA Office
> +1-702-876-2882; Fax
> +1-702-482-7903 Cell +1-206-409-2368; Virtual +1-408-627-7706
> Skype: shlepnev
>
> www.simberian.com
> Simbeor - Accurate, Fast, Easy and Affordable Electromagnetic Signal
> Integrity Software
> 2010 and 2011 DesignVision Award Winner
>
>
> -----Original Message-----
> From: Lee [mailto:leeritchey@xxxxxxxxxxxxx]
> Sent: Friday, August 15, 2014 9:47 AM
> To: shlepnev@xxxxxxxxxxxxx; jeff.loyer@xxxxxxxxx;
> Gert.Havermann@xxxxxxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: Re: [SI-LIST] Re: AW: fiber weave effect
>
> We have built many test PCBs with a variety of glass weaves of
> mechanically
> spread glass, done for laser drilling not SI, to see what control can
> be had
> over skew using such materials. The results have been very good. Skew
> of
> less than 2-3 pSec over 16". We have also evaluated two materials from
> Isola designed to minimize skew and found similar excellent results.
>
> These are GigaSync and a new material tentatively called ISE-41. They
> provide very low skew, independent of the glass weave style.
>
> -----Original Message-----
> From: Yuriy Shlepnev
> Sent: Friday, August 15, 2014 9:17 AM
> To: jeff.loyer@xxxxxxxxx ; Gert.Havermann@xxxxxxxxxxx ;
> si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: AW: fiber weave effect
>
> Hi Jeff,
>
> Thank you for the comments. The numerical experiment actually predicts
> your
> "intuitive" conclusion on the relationship between trace pair
> dimensions and
> observed skew (even for not spread glass type). I just did not find
> published confirmation of that observation. Considering the
> experimental
> data, we will follow your advice and try to make it less "anecdotal"
> :-)
>
> I totally agree with you on the need for the statistical investigation
> of
> the effect. To make it possible, the first step is to develop a fast
> macro-model for transmission line with inhomogeneous and possibly
> pseudo-random distribution of the dielectric properties along and
> across.
> Development of such model was the focus of the theoretical part of the
> paper
> - how to make dielectric properties change along and across the line
> similar
> to the behavior of composite and without violation of casualty. The
> first
> application was to evaluate the worst case scenario. The next
> application
> would be statistical analysis. Though, as you mentioned, the actual
> distribution of the dielectric properties is the unknown so far.
>
> Are those data below for the single-ended traces?
> Did you investigate the tightly-coupled traces?
>
> Best regards,
> Yuriy
>
> Yuriy Shlepnev, Ph.D.
> President, Simberian Inc.
> 3030 S Torrey Pines Dr. Las Vegas, NV 89146, USA Office
> +1-702-876-2882; Fax
> +1-702-482-7903 Cell +1-206-409-2368; Virtual +1-408-627-7706
> Skype: shlepnev
>
> www.simberian.com
> Simbeor - Accurate, Fast, Easy and Affordable Electromagnetic Signal
> Integrity Software
> 2010 and 2011 DesignVision Award Winner
>
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx] On
> Behalf Of Loyer, Jeff
> Sent: Friday, August 15, 2014 8:23 AM
> To: Gert.Havermann@xxxxxxxxxxx; shlepnev@xxxxxxxxxxxxx;
> si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: AW: fiber weave effect
>
> I agree with Gert. I'm also sure there is quite a bit of information
> about
> the effect of spread glass on FWE (Lee Ritchey, Isola, NovaSpeed,
> Compunetics?). And it seems intuitive that trace dimensions, relative
> to
> the weave, would influence the skew predictably. To my thinking,
> having
> traces very close together, such that their environment is more
> similar,
> should reduce the skew (since the glass is typically a little larger
> than
> the traces).
> I would also stress the need for any FWE study to use many boards with
> many
> instances of test structures on each board to accurately evaluate the
> effect. They are very subject to random effects which cannot be
> controlled:
> * Exact trace alignment to glass
> * Glass alignment to panel edge
> o May be different for warp vs. fill
> * Wandering of glass
> o Will be different for warp vs. fill
> Without many samples, you may draw erroneous conclusions from anecdotal
> evidence.
> For instance, below is a plot of skew between the "p" and "n" of
> several
> samples on our 10 original test boards (the 10" coupons). Note the
> significant difference in skew, depending on the particular sample. If
> you
> happened to measure "Bd10", you would conclude a maximum of 30ps of
> skew;
> "Bd9" would only have 5ps of skew (these boards were part of the same
> build,
> manufactured identically at the same time).
>
> Here's the raw data, in case the figure doesn't come out (2 different
> formats, raw text and original format):
> 0 Degree Rotation with soldermask
> Bd1 Bd2 Bd3 Bd4 Bd5 Bd7 Bd8 Bd9 Bd10
> Layer Orientation Length Sample Direction Polarity
> Sample ID "skew (p2-p1)
> (+ = m1 on left)"
> 1 V 10 01 1 1 LYR01OVL10S01D1 1
> 1
> 9 6 -1 -3 -3 5 -4
> 1 V 10 02 1 1 LYR01OVL10S02D1 5
> 0
> -7 -2 3 3 5 -3 12
> 1 V 10 03 1 1 LYR01OVL10S03D1 0
> 2
> 8 5 -2 0 -4 4 -15
> 1 V 10 04 1 1 LYR01OVL10S04D1 6
> 1
> -9 -3 5 0 5 -3 20
> 1 V 10 05 1 1 LYR01OVL10S05D1 -2
> 0
> 10 9 -3 0 -3 2 -20
> 1 V 10 06 1 1 LYR01OVL10S06D1 9
> 0
> -9 -4 5 0 4 2 23
> 1 V 10 07 1 1 LYR01OVL10S07D1 -1
> 3
> 9 7 -2 0 -2 0 -22
> 1 V 10 08 1 1 LYR01OVL10S08D1 8
> 1
> -5 -4 5 -1 3 3 29
> 1 V 10 09 1 1 LYR01OVL10S09D1 -4
> -2
> 5 7 -4 3 -3 -1 -26
> 1 V 10 10 1 1 LYR01OVL10S10D1 10
> 5
> -3 -2 4 -3 2 6 26
>
> 0 Degree Rotation with soldermask Bd1 Bd2 Bd3 Bd4
> Bd5
> Bd7 Bd8 Bd9 Bd10
> Layer Orientation Length Sample Direction Polarity
> Sample ID skew (p2-p1)
> (+ = m1 on left)
> 1 V 10 01 1 1 LYR01OVL10S01D1 1
> 1
> 9 6 -1 -3 -3 5 -4
> 1 V 10 02 1 1 LYR01OVL10S02D1 5
> 0
> -7 -2 3 3 5 -3 12
> 1 V 10 03 1 1 LYR01OVL10S03D1 0
> 2
> 8 5 -2 0 -4 4 -15
> 1 V 10 04 1 1 LYR01OVL10S04D1 6
> 1
> -9 -3 5 0 5 -3 20
> 1 V 10 05 1 1 LYR01OVL10S05D1 -2
> 0
> 10 9 -3 0 -3 2 -20
> 1 V 10 06 1 1 LYR01OVL10S06D1 9
> 0
> -9 -4 5 0 4 2 23
> 1 V 10 07 1 1 LYR01OVL10S07D1 -1
> 3
> 9 7 -2 0 -2 0 -22
> 1 V 10 08 1 1 LYR01OVL10S08D1 8
> 1
> -5 -4 5 -1 3 3 29
> 1 V 10 09 1 1 LYR01OVL10S09D1 -4
> -2
> 5 7 -4 3 -3 -1 -26
> 1 V 10 10 1 1 LYR01OVL10S10D1 10
> 5
> -3 -2 4 -3 2 6 26
>
>
> In my experience, FWE is a statistical beast which doesn't easily lend
> itself to precise analysis. We're missing some critical information,
> such
> as the statistical distribution of weave wandering. But, I welcome all
> efforts to quantify it better.
>
> Thanks for sharing,
> Jeff Loyer
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx
> [mailto:si-list-bounce@xxxxxxxxxxxxx] On
> Behalf Of Havermann, Gert
> Sent: Friday, August 15, 2014 7:35 AM
> To: shlepnev@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] AW: fiber weave effect
>
> Hello Yuriy,
>
> I'm not surprised that tight coupling is less attracted to weave effect
> on
> 3313 glass.
> Mechanically spoken, tighter coupling decreases the dielectric
> differences
> in between traces of a differential pair. Look at Figure 5 of your
> paper and
> imagine what the difference of effective dielectric surrounding the
> traces
> would be when the spacing is close to one tracewidth. The difference
> would
> be very small, especially when flat weave or even flattened weave is
> used.
>
> BR
> Gert
>
>
> ----------------------------------------
> Absender ist HARTING Electronics GmbH, Marienwerderstraъe 3, D-32339
> Espelkamp; Registergericht: Amtsgericht Bad Oeynhausen; Register-Nr.:
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> 8808; Vertretungsberechtigte GeschДftsfЭhrer: Dipl.-Kfm. Edgar-Peter
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>
> -----UrsprЭngliche Nachricht-----
> Von: si-list-bounce@xxxxxxxxxxxxx<mailto:si-list-bounce@xxxxxxxxxxxxx>
> [mailto:si-list-bounce@xxxxxxxxxxxxx] Im Auftrag von Yuriy Shlepnev
> Gesendet: Freitag, 15. August 2014 16:08
> An: si-list@xxxxxxxxxxxxx<mailto:si-list@xxxxxxxxxxxxx>
> Betreff: [SI-LIST] fiber weave effect
>
> Hello Everyone,
>
> Some results of our on-going investigation of fiber-weave effect (FWE)
> were
> recently presented at IEEE EMC 2014 symposium (at SIPI section) and the
> paper and presentation are now available at
> http://www.simberian.com/AppNotes.php - see #2014_04.
> One of the interesting outcomes was practically negligible FEW impact
> on the
> tightly coupled traces on spread fiber fabric (voltage coupling
> coefficient
> about 0.2). We have observed it both on strip and micro-strip (one
> sheet of
> dielectric fabric) configurations.
> We did not find any published confirmation of this result. Any comments
> or
> thoughts?
>
> Best regards,
> Yuriy
>
> Yuriy Shlepnev, Ph.D.
> President, Simberian Inc.
> 3030 S Torrey Pines Dr. Las Vegas, NV 89146, USA Office
> +1-702-876-2882; Fax
> +1-702-482-7903 Cell +1-206-409-2368; Virtual +1-408-627-7706
> Skype: shlepnev
>
> www.simberian.com<http://www.simberian.com>
> Simbeor - Accurate, Fast, Easy and Affordable Electromagnetic Signal
> Integrity Software
> 2010 and 2011 DesignVision Award Winner
>
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