Influencing Precision-Determining Weld Seam Properties in Laser Welding of Copper and Aluminum by Spatial Superposition of 445 nm and 1070 nm Wavelength Lasers

For the contacting of battery cells, a stable and time-efficient joining process is required, whereas primarily copper and aluminum materials with high electrical conductivity are used.To ensure a high level of automation and process efficiency, laser micro welding has established itself in industrial applications.Single-mode fiber lasers in the near-infrared range with high brilliance offer the possibility of achieving high welding depths, although more than 90% of the initial laser power is lost due to reflection losses irradiating copper materials [1].Laser beam sources in the blue emission spectrum, by contrast, have higher absorption in copper or aluminum, but cannot yet be focused to comparably small spot diameters in the required power range.To combine the advantages of both approaches, this paper follows the principle of spatial beam superposition of 445 nm and 1070 nm lasers, pursuing the goal of influencing precision-determining weld seam properties of copper and aluminum.This includes the formation of the melt pool, the consistency of the process regarding the welding depth and the influence on the surface roughness.As materials, Cu-ETP, CuSn6 and EN AW-6082 are analyzed to investigate the influence of different thermal conductivities on the process in addition to different base materials.