Direct soldering of 5A06 Al alloy using a Ti alloy mesh reinforced SAC305 composite solder

5A06 aluminum alloy exhibits excellent properties such as low density, high strength, and high electrical conductivity, which has been widely used in microwave communication components. However, the dense oxide film on the Al alloy surface hinders its direct soldering with electronic components. In this study, Ti alloy mesh reinforced SAC305 active composite solder was employed to solder 5A06 Al alloy. The effects of soldering time on the microstructure and mechanical properties of joints were investigated. Results showed that the reaction products in the solder seam changed from Al 3 (Ni, Cu) 2 , Al 2 Cu, and (Cu, Ni) 6 Sn 5 multiphase to the Al 3 (Ni, Cu) 2 single phase with the extension of soldering time. The diffusion of Al from the substrate into the solder seam controlled the phase transformation process of the microstructure. The increase of reaction products and the reinforcement of the Ti alloy skeletons in the solder seam improved the shear strength of joints, and the maximum strength value of 73.67 MPa was obtained for the joint soldered at 425 °C for 30 min with a pressure of 0.5 MPa.