Die bonding using submicrometer Ag-coated Cu particles and enhancement of bonding strength by resin infiltration

To form a bondline that is suitable for high-power dies, die bonding using submicrometer Ag-coated Cu particles was performed at temperatures above 200 °C. The solid-state Ag dewetting behavior was found to be sensitive to temperature. The formation of bump-like structures on the particle surface and slight bonding between the particles were observed after heating for 20 min at 225 °C. After heating at 250 °C, a rougher surface, strong bonding between the particles, and out-diffusion of Cu through the Ag layer were observed. As a result, the outermost phase was determined to be a Cu₂O phase. The bonding strength of the die increased with increasing bonding temperature and time. Although a die bonded for 20 min at 250 °C without the application of any bonding pressure initially exhibited a strength of 2.250 MPa, the strength increased to 19.991 MPa with increased displacement as a result of resin infiltration and curing. This paper is the first report on the feasibility of die bonding using in situ dewetting behavior with submicrometer Ag-coated Cu particles.