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.