Ryan, The internal impedance of a trace or slab is obviously going to be higher for nickel. But, it might have little effect on the total inductance p.u.l. and on the characteristic impedance of a transmission line overall. Though, the resistive losses in such line are going to increase considerably. Also, take a closer look at the imaginary part of the characteristic impedance. Here are internal resistance and inductance p.u.l. for a single rectangular conductor 5 mil by 1.4 mil made of nickel: f=1 KHz; R=15.16 Ohm/m; L=1.6 nHn/m (trace thickness is about 0.2 skin depths - almost DC solution); f=1 MHz; R=44.31 Ohm/m; L=0.627 nHn/m (trace thickness is about 6 skin depths); f=1 GHz; R=1244 Ohm/m; L=0.019 nHn/m (trace thickness is about 209 skin depths). Copper conductor resistance and inductance p.u.l. for comparison: f=1 KHz; R=3.82 Ohm/m; L=2.72 fHn/m (DC solution); f=1 MHz; R=3.82 Ohm/m; L=2.71 fHn/m (trace thickness is about 0.5 skin depths); f=1 GHz; R=26.66 Ohm/m; L=0.4 fHn/m (trace thickness is about 17 skin depths); Bulk resistivity of nickel is assumed to be 6.85e-8 Ohm-m, and relative permeability is 600, resistivity of copper 5.8e-8 Ohm-m. It is easy to do the same estimations for a gold-plated nickel trace for instance. Yuriy Shlepnev Simberian Inc. shlepnev@xxxxxxxxxxxxx -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of ryansatrom Sent: Wednesday, May 10, 2006 7:08 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Microstrip Trace under Nickel Hello All- I have been concerned with a microstrip trace traveling under a slab of nickel. There is only a .020" gap between the trace and the nickel. I have done simulations in HFSS to confirm that the Nickel has minimal effect on the impedance. However, it brought up an interesting discussion point that i don't really understand: How does the magnetic properties of a material effect Signal Integrity? I understand that some traces are made out of nickel. But they are typically plated with enough gold that any signal in the MHz and higher will only travel in the gold due to skin effect. Nickel has a relative PERMEABILITY of about 600. Does this effect anything? Thanks for any help on this. Regards Ryan Satrom Everett Charles Technologies ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org 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