Laser metal powder bed fusion of pure copper with green and infrared wavelength for power electronics applications

Power electronics feature small functional structures, which are preferably made of pure copper and are built on sensitive ceramic-based substrates, so called Direct Bonded Copper (DBC) substrates. A novel additive manufacturing (AM) approach employs the laser powder bed fusion (PBF-LB/M) process to manufacture the functional structures directly onto the DBC, eventually enabling the reduction of manufacturing cost and effort. Processing of pure copper in the PBF-LB/M process is challenging due to its reflectivity and its thermal conductivity. Additionally, using a DBC in the PBF-LB/M process leads to complex multi-material interactions. Focusing on the application, the processability of pure copper with a green and an infrared laser in the same machine setup was investigated. The influence of laser wavelength and process parameters on the resulting part properties was analyzed, differences between both wavelengths were pinpointed, and suitable parameter sets were identified.