We have a header in a prototype system with brass sprung contacts with gold 
plate over nickel, contacting pins which are also gold-plate over nickel.

This connector carries 3A, and is showing a strong tendency to increase in
contact resistance in field tests (up to 150 mOhm). Removing and refitting 
the connector takes the contact resistance back to "as new" (<40 m Ohm).. The 
connectors have been examined by a test lab and pronounced OK, with no 
contamination. No deposit or oxidation is visible on the surface.

Has anyone seen similar failure mechanism? What's the physics?


Terry Davey --------------------------------  [log in to unmask]  ------