Research On Manufacturing Process And Performance Of SiC Power Module Bonding By Nano AgCu

With the continuous development of power electronics technology,the third generation of wide bandgap semiconductor represented by SiC will become the mainstream of power electronic device technology development as a result of the higher band gap,breakdown voltage and power density compared with traditional Si-based semiconductor.However,in the interconnection material,the existing packaging material system has been unable to meet the requirement of the third generation of semiconductor power devices in high temperature working environment.As the SiC chip has the requirement of "low temperature interconnection,high temperature service" for bonding materials,scientists have done a lot of research on Nano-Ag and found that it has good thermal and electrical conductivity while it also has disadvantages of high porosity and easy migration.In this paper,the sintering properties of Nano-AgCu material and its practical application in SiC devices were investigated.In this paper,Nano-AgCu binary alloy particles were prepared by chemical reduction method,and the Nano-solder paste was prepared by adding the organic solvent.This paper focuses on the sintering process,properties and application of Nano-AgCu solder paste.The effects of sintering temperature,sintering time and sintering pressure on the sintered structure were investigated by sintering under different process conditions,and the optimum process parameters were found.In order to explore the performance in practical application of Nano-AgCu solder paste,the SiC full-bridge power drive module bonding by the Nano-AgCu solder paste was designed and fabricated.The high temperature performance of the module was tested to determine its high temperature operation stability.In addition,two kinds of comparative materials were added to the SiC power chip interconnection,and the performance of Nano-AgCu was judged by comparison in practical device applications.Finally,the samples were subjected to temperature cycles tests and high temperature aging tests to study the reliability of Nano-AgCu solder paste.It found that time and temperature were the most important factors influencing the sintered structures and properties.When the size of nano particles is about 10 nm,the sintering temperature must be higher than 250 ℃ nanoparticles in order to sintering fusion effectively,and the longer the holding time is the denser the sintering organization is.In contrast,the effect of sintering pressure is smaller.When the pressure is greater than 5MPa,the mechanical properties of the joint is no longer better even if exerting greater pressure.It found that the best electrical conductivity is 6.1 μΩ·cm and the best thermal conductivity is 94.9W/m K of the Nano-AgCu solder paste by testing.So that the Nano-solder paste is fully enough to meet the working requirements of high-power SiC chips.Finally it found that the residual organics have adverse effect on the sintered tissue when testing the samples after sintering.So the preparation and sintering process of the Nano-AgCu paste still need further study to improve.