Predicting the failure rate of electrical contacts by modeling the contact resistance distribution

Abstract

Several versions of a computer model were developed to predict contact resistance distributions for electrical contacts. In the models CR1, CR2, and CR3, it was assumed that the surface asperities of a contact metal are spherically shaped and always undergo purely elastic deformation. A comparison with actual gold contacts showed that CR1 and CR3 predicted the resistances of clean contacts reasonably well. The largest percent error between the model prediction and an actual measurement was 78%. The absolute error in this case was only 0.097mΩ. CR2 has not been tested.

For the model CR1P, it was assumed that the spherically-shaped asperities can undergo plastic deformation if the deformation is large enough. CR1P is an important step in modeling the degradation of contacts: thin film that can contaminate a contact surface are broken, and electrical contact made, only where an asperity is plastically deformed. A failure rate equation and the method of uniform residuals are two methods described in this thesis that can predict the failure rate of contacts based on the contact resistance distribution. Examples of each method are provided.