Suitability of Different Anodic Aluminum Oxide Layer Morphologies and Metallization Processes for the Assembly of Surface Mount Devices by Reflow Soldering on Aluminum-Based Substrates

Circuit carriers perform various functions within electrical systems and products. This includes being the assembly platform for various components. To mount these components, soldering processes are predominantly used because of economic and technical benefits compared to other assembly technologies. Therefore, novel circuit carrier technologies should be compatible with soldering processes to compete with the state of the art. One of these innovative circuit carrier technologies is based on anodized aluminum substrates, which are characterized by their low cost and low thermal resistance. In this article, circuit carriers made of anodized aluminum with two different oxide morphologies being investigated. In addition, three different metallization processes were compared with regard to their suitability for a reflow soldering process for the assembly of surface mount devices (SMDs). In order to evaluate the assemblies, the force required to shear off the SMDs was measured before and after a cyclic thermal shock test (TST). One of the three investigated metallization processes yielded circuit carriers based on anodic aluminum oxide that enabled reflow soldering of the given SMD components. It was determined that both, the layer morphology and the metallization process, had an influence on the measured shear forces before and after TST.