Effect of Sintering Conditions on Microstructure and Mechanical Strength of Cu Micro-Particle Sintered Joints for High-Power Semiconductor Module Applications

Abstract

In this study, the feasibility of low-cost micro-sized Cu-sintering technology for high-power semiconductor packaging has been evaluated. A Cu paste with micro-sized Cu powders and a metal content of approximately 76 % as a bonding material was fabricated. The sinter-bonding reactions and mechanical shear strengths of Cu-sintered joints were evaluated at different sinter bonding pressures and temperatures for 10 min during the sintering process. The thickness of the Cu sintered joints decreased with increasing sintering pressure and temperature. Good interfacial uniformity and stable metallurgical microstructures were observed in the Cu joints sintered at a sintering pressure of 10 MPa and a sintering temperature of 300 °C. It was confirmed that a pressure and temperature assisted sintering process could create relatively dense sintered layers and good interfacial uniformity in the Si chip/Cu-sintered layer/DBC joints. The die shear strength of the Cu-sintered joints increased with increasing sintering pressure and temperature. Despite a short sinter-bonding duration of 10 min, relatively good metallic bonding and dense sintered microstructures created by a sintering pressure of 10 MPa resulted in shear strength of approximately 20 MPa of the Cu- sintered joints. Key words: Cu paste, Cu sintering, Cu powder, Power electronics, Sinter-bonding, Shear strength