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 ...

Examples

Embodiment 1

[0013] Dissolve 157g of silver nitrate in 1L of water, and add 50g of ammonia water while stirring to obtain a silver-containing aqueous solution. Add 30 mL of hydrazine hydrate to 1 L of water, adjust the pH to 12 with NaOH, add 10 g of polyvinylpyrrolidone and 4 g of oleic acid, and stir evenly to obtain a reducing solution. Stir mechanically, control the reaction temperature at 35±3°C, drop the silver-containing aqueous solution into the reducing solution within 2 hours, and add NaOH solution dropwise at the same time to control the reaction pH value to 12±0.5, and then stir for 10 minutes after the addition is completed to obtain black nano Silver suspension, continue to stir, add nitric acid dropwise until the pH value of the suspension is 6, stir for another 20 minutes, then let it stand for precipitation, wash the powder with pure water until the conductivity of the filtrate is reached, then soak and wash the powder with ethanol once, filter to dry, dry at 70°C, and siev...

Embodiment 2

[0015] Except that oleic acid was changed to linoleic acid, other materials, dosage and process were consistent with Example 1. Powder test results: tap density 2.56g / ml, specific surface area 3.358m 2 / g, the average particle size of the particles is 102nm, and the XRD analysis is 100% Ag.

Embodiment 3

[0017] Except changing 50g of ammonia water into 10g of ethylenediaminetetraacetic acid disodium salt, other materials, consumption and process are consistent with embodiment 1. Powder test results: tap density 2.44g / ml, specific surface area 3.971m 2 / g, the average particle size of the particles is 81nm, and the XRD analysis is 100% Ag.

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 ...

Examples

Embodiment 1

[0013] Dissolve 157g of silver nitrate in 1L of water, and add 50g of ammonia water while stirring to obtain a silver-containing aqueous solution. Add 30 mL of hydrazine hydrate to 1 L of water, adjust the pH to 12 with NaOH, add 10 g of polyvinylpyrrolidone and 4 g of oleic acid, and stir evenly to obtain a reducing solution. Stir mechanically, control the reaction temperature at 35±3°C, drop the silver-containing aqueous solution into the reducing solution within 2 hours, and add NaOH solution dropwise at the same time to control the reaction pH value to 12±0.5, and then stir for 10 minutes after the addition is completed to obtain black nano Silver suspension, continue to stir, add nitric acid dropwise until the pH value of the suspension is 6, stir for another 20 minutes, then let it stand for precipitation, wash the powder with pure water until the conductivity of the filtrate is reached, then soak and wash the powder with ethanol once, filter to dry, dry at 70°C, and siev...

Embodiment 2

[0015] Except that oleic acid was changed to linoleic acid, other materials, dosage and process were consistent with Example 1. Powder test results: tap density 2.56g / ml, specific surface area 3.358m 2 / g, the average particle size of the particles is 102nm, and the XRD analysis is 100% Ag.

Embodiment 3

[0017] Except changing 50g of ammonia water into 10g of ethylenediaminetetraacetic acid disodium salt, other materials, consumption and process are consistent with embodiment 1. Powder test results: tap density 2.44g / ml, specific surface area 3.971m 2 / g, the average particle size of the particles is 81nm, and the XRD analysis is 100% Ag.

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