Welding strategies for joining copper and aluminum by fast oscillating, high quality laser beam

In this paper we present advances in strategies for joining dissimilar materials like copper and aluminum to realize battery connections by implementing distinct laser welding strategies with a fast oscillating single mode laser beam. The high beam quality enables a stable in coupling into high reflective copper connectors with low spatter events. To achieve joints with high electric conductivity a beam oscillation pattern is executed in order to create adequate cross-sections to enables high current flow. This is crucial for fast battery charging and extended lifetime of the batteries. The mechanical stability is achieved in a micro structured manner in such a way wherein the created intermetallic phase zone between copper and aluminum is minimized by implementing very accurate and very small metal mixture through compression of isotherms and melt flow guidance. TRUMPF's new generation of the product line TruFiber together with matching scanner optics (PFO series) have been implemented to demonstrate the above-mentioned strategy.