Topographical and Microstructural Effects of Laser Surface Texturing on Tin-Coated Copper Electrical Connectors Under Load Cycling

Increasing demands on modern connector materials for automotive applications, driven by the trends in miniaturization and electrification, require higher operating temperatures and lower contact normal loads. These lead to increased wear, begging the need for upgraded connector materials. In order to improve the electrical and wear behavior of an existing surface finish, the use of direct laser interference patterning (DLIP) on tin-plated copper contacts is explored. The focus of this paper lies on the evolution of the electrical resistance between textured contacts and a probe with an inert coating under normal loading. The microstructural and topographical changes due to DLIP as well as indentation during the contact resistance measurement are investigated by white light interferometry, scanning electron microscopy, and focused ion beam. The patterns change the primary deformation mechanism of the connector surface, which facilitates the fracture of electrically insulating oxide layers. This in turn leads to a decreased contact resistance in the considered load range, compared to the nontextured samples.