The degradation of aluminum-to-tin plated electrical connections under
fretting conditions has been studied. In addition to contact resistance
measurements, scanning electron microscopy (SEMI and X-ray fluorescence
(EDX) analysis were used to study the processes involved. The results
showed that fretting adverselyaffects the contact resistance of aluminum-totin
plated connections, which show a rapid increase and substantial
fluctuations after prolonged exposure to fretting. Two sustained plateaus in
the contact resistance characteristics were observed: one coinciding with the
melting voltage of tin and aluminum and the other in the range
corresponding to the voltage range of the melting, sublimation and
decomposition of the oxides and vaporization of contact materials. The
effects of fretting were reduced significantly by applying higher contact
loads. SEM and EDX analysis revealed that considerable damage of the
contact zones resulted from the fretting action and substantial exchange of
material occurred