Low-Temperature Bonding Process by Silver Nanoparticles Paste for Power Electronic Devices

A low-temperature bonding process using silver nanoparticles paste has been developed in air at temperatures of 150-250 degrees C under 5 MPa. The resistivity and hardness of the sintered Ag layer significantly improved when the sample was isothermally annealed above 180 degrees C. The microstructural evolution in the Ag nanoparticles paste at various bonding temperatures has been characterized, and their corresponding bonding strength analyzed. The results revealed that the joints can be successfully bonded at the lowest temperature of 150 degrees C for 1 h and at 180 degrees C for 10 min. No damage was found at the bonded interface after shear tests. In addition, thermal cycle tests were performed, and the microstructure evolution of the joints remained the same after the thermal cycle tests.