Silver Bonding Wire – An Alternative for Mechanical Sensitive Chip Configurations in Automotive Electronics Packaging

Silver (Ag) bond wires are mainly used in consumer products as a reliable low-cost alternative to gold (Au) bond wires. In previous investigations, we have shown that silver wires also have potential for use in the automotive sector [1]–[4], where the materials are exposed to particularly harsh environmental conditions. In order to understand the influence of these conditions in the electronic package on the silver-aluminum material system, we carried out extensive studies on test packages built on laboratory level. For the future development of challenging automotive devices, it will be important to have a cooperation between semiconductor package developer and material supplier with an assist of characterization specialists. In this project, we formed a three-party project in which characterization specialists, package developer, and wire manufacturer collectively conduct a feasibility study of a new Ag wire material for automotive application. Two wire types (standard Ag wire and new type of Ag wire GX2s) were chosen for the investigation in direct comparison regarding long-term reliability. Samples were built under mass production conditions and then subjected to various reliability tests following AEC-Q006 requirements. Subsequently, mechanical characterizations by means of ball shear and pull tests as well as high resolution SEM microstructure analyses on cross-section samples are applied. In the paper, results of the different tests will be summarized, but a more in-depth analysis will be given to the temperature cycle test (TCT), where the most significant differences between the sample variations occurred. Overall, the results show the importance of the knowledge for the material reliability upfront a device qualification process (robustness validation) and give further guidance for material selection.