Bonding Below 150°C Using Nano-Ag Film for Power Electronics Packaging

Achieving high strength and reliable bonding below 150°C using Ag nanoparticle pastes is still a challenge. This work developed an organic-free nano-Ag multilayer film consisting of a compact layer and a loose layer using pulsed laser deposition (PLD). A high shear strength of 71.2 MPa was achieved with bonding at 150°C, well above the reported values. A value of 18.6 MPa was achieved even with bonding at 50°C, meeting the MIL-STD-883 K standard requirement. The shear strength of sintered joints was strongly dependent on the diffusion behavior and microstructure evolution of loose layers. The sub-10-nanometer grains and high quantity of lattice disorders in the Ag nanoparticles induced a high diffusion driving force, ensuring high-strength bonding inside the bondline. In addition, pre-bonding and nano-bump effects of the deposited compact layer enhanced the interfacial bonding between bondline and metalized surfaces. This work provides a promising method for robust die attachment below 150°C.