Methodical approach for tribo-electrical and topographical tailoring of Cu-Sn connectors with extended direct laser interference patterning

Due to increased electrification and the uprise of autonomous driving, the number of electrical contacts per passenger vehicle is continuously increasing. In the assembly line, these multipolar connectors are usually mated manually by the operator, without the possibility of using special equipment and, consequently, must therefore not exceed a standardized limit value for the mating force. By using extended direct laser interference patterning (xDLIP) technology, the insertion force of electrical contacts is effectively reduced, increasing the total number of available electrical poles per connector socket. In this study, we have evaluated a wide range of structural parameters (different feature sizes and orientations) on Sn-coated Cu connectors. For all configurations, we have measured the electrical contact resistance as well as the insertion force for one insertion cycle. Scanning electron microscopy, energy dispersive x-ray spectroscopy and focused ion beam cross-sections were used to assess the newly generated topographies and to reveal the microstructure of both, the coating and the substrate. Cu-Sn connectors tailored with xDLIP show a decreased insertion force while mating with only marginal changes in the electrical contact resistance (ECR) for the first insertion cycle compared to unprocessed standard connectors. Summarizing, this work presents a holistic, methodical approach to tailor connectors.