高可靠性、低成本瞬态液相键合用于功率模块大面积互连

In this study, porous Cu- and Sn-based solder were employed as bonding materials for transient liquid phase (TLP) bonding. The high specific surface area of porous Cu facilitated rapid reaction with Sn, forming intermetallic compounds (IMCs) and enabling the formation of stable, reliable joints within a reduced processing time. Postbonding analysis revealed that the joints consisted of Cu and high-melting-point IMCs, ensuring excellent high-temperature reliability. To determine optimal bonding parameters, experiments were conducted under varying conditions. Cross-sectional characterization and shear strength testing were systematically evaluated to identify suitable bonding parameters. The optimized bonding parameters were established as 20 min of bonding time, 0.5 MPa pressure, $250~^{\circ }$ C temperature, and 52 wt% Cu. Under these conditions, an average shear strength of 49.2 MPa was achieved. Thermal conductivity measurements were performed after the TLP bonding process. The results yielded an average value of 112.3 W/(m $\cdot $ K) at room temperature, decreasing from 112.3 to 102.6 W/(m $\cdot $ K) between room temperature and $200~^{\circ }$ C, demonstrating excellent thermal performance at elevated temperatures. The porous Cu TLP bonding was subsequently applied to large-area direct-bonded copper (DBC, $35\times 35$ mm) and heat sink interconnects. Thermal shock testing for reliability assessment revealed that the shear strength of the joints was 40.23 MPa after 1000 cycles, with microstructural analysis indicating no significant degradation. These findings confirm the long-term service reliability of the joints. This study presents a highly reliable and cost-efficient solution for large-area interconnects in power modules.