The Effect of Wiping Distance on Contact Performance

Fretting amplitude is one of the parameters which contribute to fretting corrosion failure. The amplitude of fretting was often taken from a few to as much as 100μm in electronic connectors. However, wear track size for the degraded connectors in mobile phones was reported from several tenths to 1000μm. The purpose of the paper is to explore the effect of wiping distance on contact performance with typical contact materials. Au(probe) vs. Au(coupon), Au vs. Ni, Ni vs. Au and Ni vs. Ni contact pairs were carried out fretting experiments at different amplitude from 200 to 1000μm. The same other test parameters were used in all work described thus far: 150gf normal force, 20000 numbers of fretting cycles and a cycle rate of 1Hz. The main findings are as follow: The relationship between the number of cycles required to attaining stated levels of contact resistance and wiping distance is not always linear but sometimes polynomial, which depends on contact materials. Au vs Au and Au vs Ni contact pairs do not follow the monotonous linear decline trend, but polynomial function. Ni vs Au and Ni vs Ni contact pairs decline monotonously with fretting amplitude, the longer the fretting distance, the fewer the cycles for contact resistance to degrade. If asymmetrical contact pairs are required to reduce the cost, gold metal is recommended to be used as the surface plating of coupon but not as probe, since it can significantly improve contact performance. More than 15% atomic percentage of element Au should remain on the wear track to assure relatively low and stable resistance.