Hi Istvan, Yes, we have checked photos of the glass fabric used in the paper - one of them is on slide #9 in the presentation http://www.simberian.com/AppNotes/FiberWeaveEffect_emc2014_final.pdf Thank you for sharing the data - it is impressive. What would make it even more valuable in the context of the FWE investigation (for the worst case at least) are data on the Dk and Df of the glass and resin composites. In our paper we have found Dk and Df of the composite glass and deduced the Dk and Df of the resin composite by equating parameters the homogenized mixture and measured Dk and Df (all models were Wideband Debye). Ideally, we needed parameters of the glass and resin to identify type and parameters of the mixture to have the observed homogenized values. 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 Istvan Nagy Sent: Friday, August 15, 2014 9:05 AM To: jeff.loyer@xxxxxxxxx; Gert.Havermann@xxxxxxxxxxx; shlepnev@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: AW: fiber weave effect Hi, I agree it is statistical. How luckily or unluckily the traces are aligned with the fiber weave. With spread glass the chances or probability of unfortunate alignment are reduced, but not eliminated. The other thing is for product development we have to ensure a good production yield, so we have to consider worst-case alignment, instead of a statistical "mean". For hardware design everything is considered worst-case. Some high-cost boards with high-cost components (some of our boards have production cost of $3k-$6k with all soldered components) must have 99-100% yield, so that have to be considered in the statistical assessment. Some lower cost ($10-20) boards may afford 90% yield, if they can save big on material cost. Have you checked photos of the glass fabrics to see how much percentage of the area is covered with 2-thread, 1-thread, and no-thread? Also some materials can be classified as 1D spread, some better ones as 2D spread. Please check my glass fabric photo collection in this document on the second tab: http://www.buenos.extra.hu/download/PCB_MATERIAL_LIBRARY.xls Istvan Nagy Principal HW Engineer Fortinet, Sunnyvale -----Original Message----- From: Loyer, Jeff Sent: Friday, August 15, 2014 8:22 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 -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 -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, 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> [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 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx<mailto:si-list-request@xxxxxxxxxxxxx> with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx<mailto:si-list-request@xxxxxxxxxxxxx> with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx<mailto:si-list-request@xxxxxxxxxxxxx> with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx<mailto:si-list-request@xxxxxxxxxxxxx> with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu --- This email is free from viruses and malware because avast! 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