There are a couple of potential problems. The first is space in all axes. 10 or 12 mil wide 50 Ohm lines will require pretty thick dielectric, and commensurately wide spacing to other aggressor traces to hold cross-talk to a given budgetary limit and that is not just on your SerDes lines but on your single-ended busses. The thicker dielectric is going to push your power cavities further from the PCB surface, aggravating inductance to both ICs and bypass caps. Another problem is that with that thick dielectric and wide spacing you could potentially see more timing skew from laminate weave, and other anisotropic issues with the dielectric such as varying moisture content and such. Typically above 500MHz to 1GHz dielectric losses dominate over skin. 8 mils is about the widest that I see used. Steve. jhasson@xxxxxxxxxxxxxxxxxxx wrote: > Hi, > It is often mentionned in guidelines for routing high speed differential > serial links to have a trace width between 4 and 8 mils to reduce skin > effect losses. What would be the drawback of having even larger traces > like 10 or 12 mils if any ? The setup would be to use loose coupling and > the board density is not the main concern. > > Best regards, > > JF Hasson > > ------------------------------------------------------------------ > 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 > > > > -- Steve Weir IPBLOX, LLC Teraspeed Consulting Group LLC Affiliate (866) 675-4630 Business (707) 780-1951 Fax http://www.ipblox.com Teraspeed Consulting Group 121 North River Drive Narragansett, RI 02882 (401) 284-1827 Business (401) 284-1840 Fax Teraspeed Labs 13610 SW Harness Lane Beaverton, OR 97008 (503) 430-1065 Business (503) 430-1285 Fax http://www.teraspeed.com This e-mail contains proprietary and confidential intellectual property of IPBLOX LLC ------------------------------------------------------------------------------------------------------ Teraspeed(R) is the registered service mark of Teraspeed Consulting Group LLC ------------------------------------------------------------------ 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