[SI-LIST] Re: Microstrip Trace under Nickel

  • From: "Yuriy Shlepnev" <shlepnev@xxxxxxxxxxxxx>
  • To: <ryan.satrom@xxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
  • Date: Wed, 10 May 2006 11:41:03 -0700

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
  

Other related posts: