A limited study of the effects of contact normal force, contact geometry and wipe distance on contact resistance of gold-plated contacts

The results of a limited study of the effect of contact normal force, contact geometry, and wipe distance on contact resistance are reported. Two values of normal force (50 and 120 grams), three contact geometries (cylinder, hemisphere, and elliptical dimple) and three surface conditions (clean, lubricated, or lubricated and dusted to a 50% coverage condition) were studied. Both the contact and the flats were gold-over-nickel plated. Wiping action was provided by a stepper motor-driven table over a 20-mil distance under the full normal force. It is shown that wipe distances of less than 10 mils produce stable contact resistance values at a normal force of 120 grams for the hemisphere-flat geometry, even on the dust-covered surfaces. The ellipse-flat geometry is less effective, although effective wiping action is observed at distances less than 20 mils. The cylinder-flat geometry shows marginal wiping effectiveness. For normal forces of 50 grams only the hemisphere-flat geometry shows wiping action were similar to that at 120 grams, the elliptical geometry was marginally effective, and the cylinder was ineffective.<>