An investigation of the electrical contact resistance of corroded pore sites on gold plated surfaces

Plating defects known as pores are unavoidable in most noble metal plating thicknesses used in separable electrical contact applications. Mixed flowing gas tests commonly used as accelerated life tests for connectors and sockets can attack these plating defects to create corroded pore sites on the electrical contact surface. To examine the effects of corroded pores on a gold contact finish, the chemical composition and physical appearance of the corroded pores was examined. The contact resistance at various positions on corroded pores was then measured to examine the effects normal force, geometry, wipe, and backwipe on the contact resistance. The pore sites were also examined under an electron microscope to see how the wipe mechanically displaces the corrosive film in different areas of the pore. Wipe onto the corroded pore site produced better results than landing on the pore site and wiping off, but the magnitude of the contact resistance values would be unacceptable in most dry circuit applications. The design parameters of normal force, geometry, wipe, or backwipe at the levels tested were not found to be able to produce a low and stable contact resistance when making contact to corrode pore sites on gold plated finishes.