The Effect of Initial Connector Insertions on Electrical Contact Resistance

This work attempts to quantify the effect of repeated initial connector insertions and roughness on electrical contact resistance. Experimental measurements show that the electrical contact resistance increases measurably with repeated insertions. They also show that with repeated insertions the connector spring is plastically deformed, thus causing the force closing the contact across the surfaces to decrease. A multi-scale rough surface contact model was used to estimate the actual electrical contact resistance (ECR) versus applied force curve of the connector. As expected, the multiscale ECR model predicts that the ECR will decrease with applied force. Since the contact force decreases with each insertion of the connector due to plastic deformation, the model will predict that the ECR will also increase with each insertion. When the added resistance from a measurable layer of tin oxide is included, the multiscale ECR model shows fairly good agreement with the experimental measurements.