Die sinter bonding in air using Cu@Ag particulate preform and rapid formation of near-full density bondline

Pressure-assisted sinter bonding between an Ag-finished die and an Ag-finished substrate was performed in air using an Ag-coated Cu (Cu@Ag) particulate preform to rapidly achieve a bondline with high-temperature sustainability, low-defect structure, and high thermal conductivity. The preform was prepared as a binder-free material by pelletizing 351 nm Cu@Ag particles with 20 wt.% Ag shells. At 350 °C and at pressures of 5 MPa and 10 MPa, the bonding exhibited shear strength values approaching 20 and 24 MPa, respectively, just after 30 s and the pressure increase to 10 MPa accelerated the increase in strength with increasing bonding time. Furthermore, a bondline with a near-full density structure was formed immediately after bonding for only 30 s. The fast sinter bonding and near-full density formation are mainly attributed to the initial strong contact between the particles and the particle rearrangement behavior by the sliding deformation of sintered Ag after dewetting of the Ag shells on the Cu core particles during the pressure-assisted bonding.