High-Reliability Cu-Cu₃Sn Composite Bonding for Power Electronics in Harsh Environments

To address the severe reliability challenges of bonding power electronic devices in high-temperature environments, dual-beam pulsed laser deposition (PLD) technology was employed to construct Cu-Cu₃Sn biphasic joints. By advancing a portion of the intermetallic compound (IMC) formation to the deposition stage, the joint preparation time was reduced to just 10 min. During bonding, a network-like Cu₃Sn phase and sintered Cu phase were formed in situ, interpenetrating each other, resulting in a room-temperature shear strength of 105 MPa for the joint. After aging at 300°C/1500 h, the shear strength of the joint was still stably maintained at around 75 MPa. Following 600 thermal shock cycles between −60°C and 150°C, the joint interface remained intact, exhibiting a lifespan 50% to 100% longer than that of sintered Cu and full Cu₃Sn joints. Microstructural analysis reveals that the continuous Cu₃Sn network reduces joint porosity, effectively blocks the diffusion of oxygen atoms, and enhances the oxidation resistance of the joint. The sintered Cu skeleton can alleviate thermal stress concentration and crack evolution under thermal load, thereby improving the thermal shock resistance of the joint. The composite joint prepared in this work meets the rigorous requirements for high-temperature oxidation resistance and thermal fatigue toughness, providing a promising solution for power electronic packaging in harsh service environments.