Reliability Analysis of Cu Sintered Die-Attach for SiC Power Devices: Mechanical, Electrical, and Thermal Evaluation

This study presents the development and characterization of a novel Cu paste for use in pressure-assisted sintering die-attach processes, applied to SiC power devices. The Cu paste was self-developed, and the sintering process was conducted at 250°C for 3 minutes under a pressure of 20 MPa. The shear strength, on-resistance, and junction-to-case thermal resistance reliability were evaluated through a 1000-hour hot temperature storage test and a 1000-cycle temperature cycling test. Initially, the Cu sintered samples display robust characteristics, boasting high shear strength (>91.8 MPa), low thermal resistance (<0.218°C/W), and minimal on-resistance (<18.44mΩ). Throughout the reliability experiments, there is no observed degradation in these critical properties. Subsequently, during temperature cycling and high-temperature storage, the shear strength demonstrates an upward trend with increasing holding time or temperature cycling, reaching over 120 MPa. The on-resistance values of the units remain stable exhibiting a negligible change rate of less than 1.3%, alongside a marginal 4% increase in thermal resistance values. The results suggest that both Cu-sintered Cu units and SiC units perform comparably to standard commercial Ag products. These findings underscore the potential of the developed Cu paste and pressure-assisted sintering process in achieving reliable die-attach solutions for SiC power devices.