Exploration of Key Factors for the Sintering of Micro-Nano Silver Paste

For the sintering of Ag paste, the final performance of sintered Ag joints is determined by various sintering factors. In this study, the sintering performance of a micro-nano Ag paste, which contained both Ag micro-flakes (Ag MFs) and Ag nano-particles (Ag NPs), was optimized by adjusting the weight ratio of Ag MFs and Ag NPs, the preheating temperature and the sintering pressure. The obtained Ag joints exhibited an excellent shear strength of about 76-78 MPa and a low porosity of less than 1%. Compared with the weight ratio of different Ag fillers and the sintering pressure, the preheating temperature for the sintering of Ag paste is usually ignored. However, our work demonstrated that the preheating temperature not only affected the solvent evaporation of Ag paste but also heavily influenced the microstructure of sintered Ag joints and thus determined their final shear strength.