低温烧结纳米铜焊膏的制备及其连接性能分析

The Cu nanoparticles (Cu NPs) solder paste was applied to connect high-power semiconductor devices at low temperature. The preparation method of the Cu NPs solder paste included the following steps: First, Cu NPs with an average particle size of 30 nm were synthesized by the modified polyol method. Then, the Cu NPs were dispersed in formic acid to remove the surface oxide of Cu NPs. After that, the Cu NPs were mixed with ethylene glycol to prepare solder paste with a solid content of 70%. The DBC ceramic substrate and the metallized SiC die was connected by sintering at low temperature from 160 ℃ to 320 ℃ for 5 min, and the assist pressure was 10 MPa. The morphology of the joint was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The result showed that the connection joints with high shearing strength and conductivity were formed by metallurgical bonding between the sintered Cu NPs layer and Cu pad. Coarse microstructure was formed inside the sintered joint.