Silver powder and preparation method thereof

Abstract

The invention provides silver powder and a preparation method thereof, and belongs to the technical field of metal powder preparation. In a silver-ammonia solution system, the pH of the solution before reaction and the adding sequence and dosage of the dispersing agent are adjusted, and the adding mode, adding sequence and speed of the reducing agent are cooperatively controlled, so that a large number of nano-silver crystal nucleuses are generated in the early stage of the reaction system, and the reduced silver continuously incompletely and uniformly grows on the basis of the silver crystal nucleuses in the middle and later stages of the reaction; and finally, the silver powder doped with large and small particles is formed. According to the method, the mixed silver powder of large particles with the particle size being 0.8-1.2 microns and small particles with the particle size being 0.1-0.3 microns can be obtained through a one-time liquid phase chemical reduction method, the large-particle silver powder forms a main conductive structure, the small-particle nanometer silver powder fills gaps of the silver powder and changes the contact state of the submicron silver powder, the curing temperature and the on-resistance can be reduced, and the conductivity of the submicron silver powder is improved. Therefore, the sintering activity and conductivity of the silver powder are improved, and the silver powder can be widely applied to the fields of low-temperature curing type photovoltaic cells, power semiconductor devices and the like.

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