Sintering bonding using metal nanoparticles is considered a promising die-attach technique for high-temperature operating power devices, such as SiC. However, the thermal stress produced by the difference in coefficient of thermal expansion (CTE) between the chip and substrate, often affects the reliability of this technique. To address this limitation, we analyzed a sintering bonding using Ni nanoparticles and Al microparticles composite paste. The results revealed that the Al microparticles significantly reduced the voids and cracks in the bonding layer formed by Ni nanoparticles paste. Three chips with different sizes were bonded to Cu substrates, and the bonding strength was measured. The result revealed that the bonding strengths in the samples were higher than those of the samples bonded using conventional metal nanoparticles. In addition, the fracture observation after the shear test revealed that the Al particles suffered plastic deformation. Furthermore, the high-temperature storage test at 250°C confirmed the long-term bonding reliability.