Optimization and characterization of T-joint laser welds for aluminum fin heat sink with copper base

Heat sink assemblies consisting of an A6061-T6 aluminum alloy fin and a C1100 copper base are prepared by T-joint welding using a near continuous-wave fiber laser system. The effects of the welding parameters on the tensile strength and heating rate of the heat sink assembly are investigated and compared. It is shown that the maximum tensile strength and heating rate are obtained using a laser power of 220 W, a pulse width of 8 ms, a welding speed of 2 mm/s, and an incident angle of 60°. The thermal conductivity of the heat sink prepared using the optimal welding parameters is shown to be in good agreement with the ANSYS Fluent simulation results obtained under the assumption of an ideal, defect-free joint between the copper base and aluminum fin. The tensile strength and heating rate using the optimal welding parameters are 24.31 MPa and 41.2 °C/10 2 S, respectively. The optical microscopy (OM) images show that the thickness of the intermetallic compound (IMC) layer formed at the interface between the aluminum fin and the copper base varies with the welding parameters and has a value of approximately 6 µm under the optimal welding conditions. The energy dispersive spectrometry (EDS) results and X-ray diffraction (XRD) analysis results reveal that the welding bead consists mainly of Cu, Al, and Al 2 Cu phases.