Formation of Cu-Cu Joints with High Shear Strength and High Reliability in Air Atmosphere

Copper sintering technology has a great prospect in the packaging of high power devices, and how to form Cu-Cu joints with high shear strength and high reliability is one of the preconditions for the application of copper sintering technology. In this work, a novel Cu nanoparticle (NP) paste has been developed by blending commercial Cu NPs and the mixed solvent of glycerol and terpineol. The obtained Cu NP paste exhibited a good sintering performance in air and formed high strength Cu-Cu joints (48.75 MPa) after sintering at 300°C with 10 MPa for 10 minutes. In order to verify the high reliability of these Cu-Cu joints, the high temperature storage (HTS) test at 150 °C in air atmosphere was performed. The shear strength of Cu-Cu joints increased firstly and then decreased during HTS test, but Cu-Cu joints still kept a higher shear strength (58.31 MPa) than that of the pristine Cu-Cu joints after aging at 150 °C for 1000 h. These excellent results mean that this novel Cu NP paste can be considered as a potential material for the packaging of high power devices.