Eric or others, YIKES! I would like to enquire about: * references for the 2x resistance increase, dependent on roughness/skin depth ratio. * suggestions for simulating this ... cannot just hack a tabular rlgc or sparam file [??] since the R is really R(f), unless answer to the 1st question gets me a R(f) indirectly. Need to consider this. Very serious. For 10G. Please help! Regards, Agathon On 8/29/07, Eric Bogatin <eric@xxxxxxxxxxxxxxx> wrote: > > I second Scott's important point. Above 1 GHz, skin depth is less than 2 > microns in copper. When the RMS surface roughness is larger than the skin > depth, it affects conductor loss. > > Above 3 GHz, surface roughness can almost double conductor loss. In fact, > the commonly used approximations for the impact from conductor loss, > saturate at a factor of 2 increase to the resistance when the surface > roughness is about 3 x skin depth. > > This means, even though your line width is 5 mils, it would have the > conductor loss equivalent of a 2.5 mil wide line. The conductor loss can > easily swamp the dissipation factor of even FR4, negating any benefit for > low loss materials unless you are using very wide lines. > > If you want the biggest bang for the buck in evaluating conductors, try > looking at surface treatments that allow smoother copper foils. > > --eric > > ************************************** > Dr. Eric Bogatin, President > Bogatin Enterprises, LLC > Setting the Standard for Signal Integrity Training > 26235 w 110th terr > Olathe, KS 66061 > v: 913-393-1305 > f: 913-393-0929 > c:913-424-4333 > e:eric@xxxxxxxxxxxxxxx > www.BeTheSignal.com > Fall 2007 Signal Integrity Training Institute > EPSI, SIAA, BBDP > Oct 8-12, 2007, San Jose, CA > **************************************** > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] > On > Behalf Of Scott McMorrow > Sent: Wednesday, August 29, 2007 4:11 PM > To: jeff.loyer@xxxxxxxxx > Cc: sridharam@xxxxxxxxxx; si-list@xxxxxxxxxxxxx > Subject: [SI-LIST] Re: Conductor loss reduction at High Frequency > > Surface roughness is the largest contributor we've measured for > conductor loss. There are certain low loss materials that are > constructed with high tooth copper for maximum adhesion, which show > enough loss to absolutely negate any benefit that the low loss (low tan > delta) material would have had over materials with twice the dielectric > loss. > > Interesting stuff. > > 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 > > TeraspeedR is the registered service mark of > Teraspeed Consulting Group LLC > > > > Loyer, Jeff wrote: > > My 2 cents available in the article below: > > > > http://pcdandm.com/cms/content/view/2572/95/ > > > > > > Jeff Loyer > > > > -----Original Message----- > > From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] > > On Behalf Of M Sridhar > > Sent: Wednesday, August 29, 2007 5:08 AM > > To: si-list@xxxxxxxxxxxxx > > Subject: [SI-LIST] Conductor loss reduction at High Frequency > > > > Hi Members, > > > > What are the methods by which we can reduce the conductor losses at high > > frequency?(Loss due to skin effect, Dielectric losses etc.) > > Which is the best conductor at higher frequency? in the range of 1-5 GHz > > > > Thanks, > > Sridhar > > ------------------------------------------------------------------ > > 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 technical documents are available at: > > http://www.si-list.net > > > > List archives are viewable at: =20 > > //www.freelists.org/archives/si-list > > or at our remote archives: > > http://groups.yahoo.com/group/si-list/messages > > Old (prior to June 6, 2001) list archives are viewable at: > > http://www.qsl.net/wb6tpu > > =20 > > ------------------------------------------------------------------ > > 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 technical documents are available at: > > http://www.si-list.net > > > > List archives are viewable at: > > //www.freelists.org/archives/si-list > > or at our remote archives: > > http://groups.yahoo.com/group/si-list/messages > > 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 technical documents are available at: > http://www.si-list.net > > List archives are viewable at: > //www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages > 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 technical documents are available at: > http://www.si-list.net > > List archives are viewable at: > //www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages > 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 technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu