Surface effect induced Cu-Cu bonding by Cu nanosolder paste

Based on surface effect of nanoparticles, excellent Cu-Cu bonding was achieved by sintering of Cu nanosolder paste. The surface melting behavior of nanoparticles and the bonding process was investigated at the temperature of 250°C to 400°C under the protection of Argon/Hydrogen gas mixtures. The antioxidative Cu nanoparticles were synthesized with high yield by an efficient method for the preparation of solder paste. The bonding achieved by thermo-compression shows great tolerance to experimental environment and the roughness of bonding substrates. The largest shear strength in this study could exceed 35MPa, which is suitable for high-density packaging of three-dimensional integrated circuits. [Display omitted] •An efficient method for synthesizing homogeneous dispersed and antioxidative Cu nanoparticles was proposed.•Surface effect of Cu nanoparticles was studied.•Cu-Cu bonding was achieved by thermos-compression.•Bonding interface and bonding strength were investigated.