Institut Maupertuis

Abstract Copper is a widely used material in the electric vehicle industry due to its excellent electrical and thermal conductivity. However, welding copper can be challenging due to its high thermal conductivity and low absorptivity at 1 µm. We discuss a new method of copper laser welding that utilizes beam shaping based on Multi-Plane Light Conversion (MPLC) technology to stabilize the melt pool for a broad range of speed and power. The welding performance of different shapes based on MPLC technology is discussed including welding penetration depth from 4 to 8 kW and from 3 to 15 m/min. In addition, live X-ray imaging was performed, as well as post-processing X-ray analysis showing that no pores were inside the welds. The X-ray analysis including pore count and capillary length for different welding parameters is described. The developed system allows for deep penetration welding up to 2.8 mm at 8 kW and 3 m/min, which may be applied to busbar welding. Deep penetration welding up to 35 m/min at 8 kW was also achieved, paving the way for applications such as hairpin welding. The welding performance of the MPLC technology-based system versus beam shaping based on a dual-core fiber laser technology system in similar conditions and no beam-shaping is shown. It includes a process window comparison with welding penetration depth and pore analysis. It demonstrates that the MPLC system enables high-quality welding at both lower and higher speeds.