Preparation method of high dispersibility superfine silver powder with adjustable grain diameter

Abstract

The invention relates to a preparation method of high dispersibility superfine silver powder with adjustable grain diameter, comprising the following steps: 1. dissolving silver nitrate and surfactant in water to prepare silver solution A; 2. dissolving ascorbic acid, PH regulator and surfactant in water to prepare reducing liquid B; 3. preparing alkaline aqueous solution C by alkaline PH regulator; dropwise adding alkaline aqueous solution C and silver solution A to reducing liquid B at the set time. PH value of the reducing liquid B and flow velocity of alkaline aqueous solution C are adjusted, so that silver power particle size can be easily adjusted and the silver power particles can grow up uniformly. The silver powder obtained by the method of the invention has the characteristics of polyhedral microcosmic appearance, good dispersibility, narrow size distribution, high tap density and good sintering character.

Description

technical field The invention relates to a liquid-phase preparation method of ultrafine silver powder, in particular to a preparation method of highly dispersed ultrafine silver powder with adjustable particle size used in electronic paste. Background technique Silver powder is the most widely used and the largest amount of precious metal powder in the electronics industry. Its morphology, particle size, uniformity, and dispersion are key factors affecting the film-forming performance of silver paste. Therefore, it can be used to make various low-temperature Curing polymer silver paste, conductive adhesive, or sintered silver paste including electrode paste for various ceramic components. The most commonly used method for preparing silver powder in large quantities at present belongs to the liquid phase reduction method. The production process and equipment of the liquid phase reduction method are simple, the production cost is low, and the product performance is controllab...

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Problems solved by technology

The technical point of preparing silver powder by liquid phase reduction method is to control the dispersion, size and uniformity of the reduced silver particles, because the ultrafine powder is easy to agglomerate in the aqueous solution, resulting in poor dispersion, which is difficult to meet the requirements of ordinary electronic paste, especially It is the printing and sintering demand of high-end silver paste. For example, the patent with application number 200510128715.6 requires subsequent heat treatment, and the concentration of reactants is low, and the output per unit volume is low, which is not conducive to mass industrial production. Although the patent with application number 200710049490.4 is silver nitrate The concentration is high, but it does not involve the selection of surfactants, and the dispersibility of the powder obtained by reduction is difficult to control

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