RE: [SI-LIST] : Contact resistance?

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From: Matt Kaufmann (matt@silicon-spice.com)
Date: Thu Apr 27 2000 - 11:16:12 PDT


The contact resistance will also vary greatly with the applied pressure
between the two contacts. A secondary effect is that the thermal
distribution across the junction can cause the contacting materials to
deform (due to thermal strains) which will affect the contact area.
Actually, it is a coupled thermal/mechanical problem since the contact area
and pressure affects the temperature distribution which then affects the
contact area and so on...

For the 1st order affect (pressure), there is an analytical relation between
pressure and contact resistance (you would need to know the
roughness/asperity of the contact surfaces.

This was part of my MS thesis so if you want some references, I can clear
away the cobwebs and get you some good ones. I didn't really look at the
effects of voltage/current - I focused more on the heat flux passing through
the junction.

-Matt

Matt Kaufmann
Senior Packaging Engineer
Silicon Spice, Inc.
matt@silicon-spice.com

> -----Original Message-----
> From: owner-si-list@silab.eng.sun.com
> [mailto:owner-si-list@silab.eng.sun.com]On Behalf Of John Spohnheimer
> Sent: Thursday, April 27, 2000 10:19 AM
> To: 'si-list@silab.eng.sun.com'
> Subject: RE: [SI-LIST] : Contact resistance?
>
>
> Talk to The J. M. Ney Company, http://www.jmney.com/
> <http://www.jmney.com/>
>
> They publish a great text - "Ney Contact Manual", that may give
> you some insight into the problem.
> Last time I checked (2-3yrs ago), they would mail you a copy of
> the manual if you gave them a call.
>
> The material is a bit dated (1973 copyright), but the basic
> physics doesn't change.
>
> Looking at Section 1.8 Constriction Thermal Effects, they have a
> ~4 page summary of how
> the constriction resistance (basically the contact resistance)
> varies with applied voltage.
>
> If you send me your fax # off-list, I'll send you the pertinent section.
>
> JVS
>
>
> -----Original Message-----
> From: bgrossma [mailto:bgrossma@td2cad.intel.com]
> Sent: Thursday, April 27, 2000 11:16 AM
> To: si-list@silab.eng.sun.com
> Subject: [SI-LIST] : Contact resistance?
>
> << File: Card for Brett Grossman >> Hi,
>
> Can anyone direct me to a decent reference on contact theory?
>
> Specifically, I am trying to get an analytical expression (or an
> intuitive understanding at least) for how contact resistance between to
> differing metals can vary as a function of power dissipated in the
> junction, and why. Kind of a funky thermal/materials problem, but I only
> want to get a ballpark estimate to see if an idea would be worth
> pursuing further.
>
> Thanks for your help,
>
> -Brett
>
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