Rapid pressure-assisted sinter bonding in air using 200 nm Cu particles and enhancement of bonding strength by successive pressureless annealing

To design an effective and realistically applicable sinter bonding process for power devices, we proposed a two-step process using a 200 nm Cu-particle-based paste to form a bondline having high-temperature sustainability and superior thermal conductance. This process involved rapid pressure-assisted sinter bonding in air followed by pressureless annealing in a nitrogen atmosphere. In the case of a paste prepared with a mixture of 20 wt.% malic acid and 80 wt.% ethylene glycol, sinter bonding at 300 degrees C and 5 MPa for only 30 s resulted in a sufficient shear strength of 23.1 MPa. The shear strength was significantly enhanced to 69.6 MPa by the additional pressureless aging for 30 min. Therefore, the two-step sinter bonding process is expected to provide an outstanding production rate as a next-generation sinter bonding process.