Method for preparing nano-scale silver powder

Abstract

The invention discloses a method for preparing nano-scale silver powder and comprises the steps of reduction reaction, solid-liquid separation and washing and drying. In the reduction reaction, aqueous solution with the silver-bearing concentration being 30-200g / L is dropwise added into the reducing solution, or aqueous solution of reducing agent is dropwise added into silver oxide suspending liquid with the silver-bearing concentration being 30-200g / L, the reaction temperature is controlled at 20-60 DEG C, and synchronously pH regulating agent is added, the pH value of the reaction solution is controlled at 10-14, then the reaction solution is stirred to obtain the silver suspending liquid. The method process is simple and easy to carry out, the obtained nano silver powder has high purity, good dispersivity, small particle diameter, higher specific surface and tap density and high drying temperature range of the powder, the self-sintering or agglomeration of the powder can be effectively controlled, and the powder can be easily dispersed in an organic carrier.

Description

technical field [0001] The invention relates to a liquid-phase preparation method of nano-scale silver powder, in particular to a liquid-phase preparation method of nano-scale silver powder applied to electronic paste. Background technique [0002] Silver powder is the most widely used precious metal powder in the electrical and electronic industry. The traditional industrial silver powder has a particle size greater than 0.2 microns, which can be used to make isotropic conductive adhesives, conductive coatings, and sintered silver pastes, such as capacitors, The typical sintering temperature for functional electrode pastes for inductors, resistors and other ceramic components is 650-850°C. The sintering temperature is high, the energy consumption is high, and the performance requirements for the ceramic substrate are also high. The preparation methods of nano-silver powder include gas phase method, solid phase method and liquid phase method, wherein the liquid phase method ...

AI Technical Summary

Problems solved by technology

When prepared by the liquid phase reduction method, because of the high surface energy of the nano-silver powder, it is easy to agglomerate in the aqueous solution, resulting in poor dispersion and low tap density, which cannot meet the needs of the electronic paste industry, and even if obtained by adjusting the reaction conditions It is also very difficult to separate the powder from such an aqueous suspension without good dispersion of nano-silver powder

The nano-silver powder used in the electronic paste industry requires good dispersibility and high tap density. However, it is precisely because of the high activity of the nano-silver powder that it is easy to self-sinter or agglomerate. The so-called nano-silver powder on the market generally does not solve the problem of agglomeration and has poor dispersibility. , the surface activity is not high, the tap density is low, it is difficult for the organic carrier to completely wet the powder when preparing the slurry, the particle size is large, and the silver layer is not dense after sintering, the shrinkage rate is large, there are many pores, and the electrical properties are poor, which cannot meet the requirements. The needs of the further development of the electronics industry

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