We have proposed a novel bonding process using Ag nanoparticles, which can be alternative to lead-rich high melting point solders. Metallurgical bonding between Ag and Cu can be achieved in Cu-to-Cu joints using Ag metallo-organic nanoparticles at a low temperature less than 573 K. The influence of bonding parameters on the bondability of Cu-to-Cu joints was examined based on the measurement of the shear strength of the joints, observation of the fracture surfaces and cross-sectional microstructures. The Cu-to-Cu disc joints were made at bonding temperatures of 533, 553 and 573 K with varying holding times of 2.5, 5 and 10 min and pressures of 1, 2.5, 5 and 7.5 MPa. The increase of bonding temperature and holding time contributed to the increase of the sintering ratio. However since sintering of Ag particles completed within 2.5 min at each bonding temperature, further increment of holding time had no significant effect on the shear strength of the joints. Under lower bonding pressure, the increase of bonding temperature leads to rise of the shear strength. The increase in bonding pressure significantly improved bonding strength and changed the fracture mode from the Ag/Cu interfacial fracture to the Ag layer fracture. As a result we can obtain the shear strength more than 50 MPa in appropriate bonding conditions. In addition, the bonding conditions providing the joint strength equivalent to those using the lead-rich high melting point solders were proposed.