Failure analysis of electroplated copper wire presents specialized types of wire breaks unique to the type of plated material. Tin and nickel have significantly different characteristics causing each one to develop its individual form of wire failures. Tin being a soft material with a tendency to interact with copper provides god adhesion. However, because of its tendency to react with copper, it generates localized areas of tin diffusion, which results in wire failure. On the other hand, nickel, a hard material, is very sensitive to grain size and ductility, and tends to generate the brittle type of wire failures. These wire failures may be confused with normal tensile or weld failure because of their appearance. Conditions present in the plating of nickel may result in a hard, less ductile nickel plate which is difficult or impossible to draw. Plated copper wire is sensitive to annealing parameters. The parameters must to be properly selected and tightly controlled. In the case of nickel plating, temperatures higher than the optimum condition cause an intermetallic layer and cavities to be formed between nickel and copper. This causes brittleness and low elongation. The overall failure analysis of plated copper wire requires proper analytical tools and methodology to identify the failure mode and determine corrective action.
展开▼
