Hi,
you have indeed a quite difficult task. I was involved in such investigations when I was young, don't remember all stuff, only fragments.
Nickel and Silver was not the best choice, depending on how the contacts work. Silver is known to oxidise, Nickel has a high resistivity, especially at high frequencies. Just some factors that have to be considered:
a. sliding mechanism to remove oxides and lubricants and moist
b. contact pressure is highly deciding the final resistance
c. number of contact points, you never have just one single transconductional point.
d. the porosity of your plating
e. insertion force vs. idling force
f. fretting actions
g. microhardness of the individual layers
h. temperature dependancy
i. arcing characteristics i.e. what happens during mating and disengageing.
j. how gastight are the microcontacts (make life, endurance etc tests)
At that time I worked with the problems (NAFI connectors) I cooperated with Teradyne. Have no adress to people there any more, but you have numerous others to chat with: NASA, CALCE, AMP, Suhner, Rosenberg, hundreds of universities, just to start digging..
Just single sparks from a passed time
Ingemar Hernefjord
Ericsson Microwave Systems
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of - Bogert
Sent: den 22 november 2004 23:59
To: [log in to unmask]
Subject: [TN] Calculation of Connector Contact DC Resistance
November 23, 2004
Folks, I have a science question. How does one calculate the DC contact resistance of a brass electrical connector contact that is plated with a nickel flash with a final plating of silver?
We have an OEM who did a milli-volt drop test using an incorrect size (oversize) pin with the aforementioned plating. The test failed. We are trying to determine what the impact is when using the oversize pin. One method would be to try to determine what the expected DC contact resistance should be based on the pin configuration. Does one calculate DC parallel resistance based on brass, nickel and silver, or just calculate based on silver? Any thoughts on this/formulas, etc. ,
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would be appreciated.
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