Vibration-induced deterioration of tin-coated connectors studied by using a force controlled fretting bench-test

The deterioration of tin-coated connectors caused by vibration was studied by using a new approach. In order to simulate the true contact situation during vibration, a controlled oscillating tangential force was applied on a model tin-contact, while the displacement was free to vary. This study shows that the friction and the amplitude of the tangential force acting on the contact are critical parameters for a contact subjected to vibration, since they have a significant impact on the relative slip at the contact interface. Almost any slip (>1 μm) resulted in an increased contact resistance in the performed experiments. Initial slip caused an increase of the contact resistance, and also an increase of the contact area with a subsequent increase in friction force. The slip came to stop, as the friction force became equal to the applied tangential force. Provided the slip was stopped before the contact failed as described, a stable contact resistance was achieved despite an applied oscillating tangential force. In all other, cases the slip continued and the contact inevitably failed. With a force controlled fretting bench test the critical tangential force for a specific contact can easily be determined, and the results can be used to predict the risk for fretting corrosion.