Ultra-pure silver powder preparation method capable of controlling particle size

Abstract

The invention relates to an ultra-pure silver powder preparation method capable of controlling the particle size. The preparation method comprises the steps of (1) preparing a silver nitrate solution, wherein the concentration of silver nitrate in the solution is 1.2 to 1.5 mol / L; (2) adding aqueous ammonia into the silver nitrate solution prepared in the step (1), and adjusting the pH to be 8 to 9; (3) dripping a hydrazine hydrate aqueous solution with the concentration of 40% to 80% into the silver nitrate solution in the step (2) at the speed of 0.1 to 1 mL / min, so as to obtain silver powder slurry; and (4) filtering the silver powder slurry obtained in the step (3), washing the filtered silver powder slurry with deionized water for three times, and drying wet silver powder obtained after filtration under nitrogen protection to obtain silver powder. According to the preparation method, during the preparation process of ultra-pure silver powder, any protective agent and dispersing agent are not added in the reaction system, and organic matter residues are avoided; and when hydrazine hydrate is used for reducing silver nitrate, the reaction speed of silver nitrate reduction through hydrazine hydrate is accurately controlled through accurately controlling the flow of the hydrazine hydrate aqueous solution, so that the particle size of the ultra-pure silver powder is accurately controlled.

Description

technical field [0001] The invention relates to a preparation method of ultrapure silver powder with controllable particle size, in particular to a preparation method for controlling particle size ultrapure silver powder without adding any protective agent and dispersant. Background technique [0002] Silver powder has excellent electrical conductivity and chemical stability, and is one of the most widely used precious metal powders in the electronics industry. In recent years, with the rapid development of the electronics industry, the demand for electronic pastes with silver powder as the main functional phase has grown rapidly. Silver powder is the most critical raw material for preparing electronic paste. The performance of silver powder directly or indirectly affects the performance of the paste and the final conductor, such as film forming process, film thickness change, electrical property change, solderability, adhesion, etc. Therefore, the development of high-quali...

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Problems solved by technology

[0007] The above methods are to achieve the purpose of controlling the particle size of the silver powder by adding a dispersant. However, since electrical contacts have high requirements on the purity of the silver powder, no organic matter is allowed to remain. Therefore, no organic matter is allowed to be added during the powder production process. To control the particle size and dispersibility of silver powder, how to control the particle size of silver powder without protective agent and dispersant is a constant problem in the industry to meet the needs of contact products

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