CN101327521B - Wet chemical preparation method containing spherical silver powder - Google Patents

Abstract

The invention discloses a wet chemical preparation method of a spherical silver powder. The method includes the following steps: the temperatures of silver nitrate solution and FeSO4.7H2O solution are adjusted to 0 to 20 degrees; the two solutions are evenly mixed through agitation until the mixed solution turns yellow to produce silver powder, wherein, the weight ration of silver nitrate and theFeSO4.7H2O solution is 1 to (2 to 8); the silver powder is precipitated from the mixed solution, then the silver powder is washed in deionized water and absolute ethyl alcohol in turn, and then the silver powder is dried. The material used in the invention is non-toxic, the method is simple and is applicable to mass production, the silver powder prepared in the method has the advantages of high degree of sphericity, rough surface, and narrow distribution of particle sizes.

Description

A kind of wet chemical preparation method of ball shape silver powder

Technical field

The present invention relates to the silver powder technology of preparing, particularly relate to the preparation method of ultra-fine dense packing, spherical shaped silver.

Background technology

The silver slurry is the most important material of electronics industry, along with the microminiaturization of electronic product and the development of micro-nano technology, prepares various conductive pastes with powder (especially silver powder), is widely used in the coating and circuit interconnection of printed circuit.Preparing at present both at home and abroad the method that silver powder generally adopts has: thermal decomposition method, electrochemical process, aeroponics, chemical reduction method etc.Aeroponics and chemical reduction method are mainly adopted in the preparation of ball shape silver powder.Aeroponics can obtain the ball shape silver powder of better roundness, but the powder diameter is greater than 20 μ m, and the particle diameter skewness, the production cost height, cost an arm and a leg, easily introduce other metal impurities, and process equipment is required high, technical sophistication, investment is big, is not suitable for electric slurry production needs.Chemical reduction method can use comparatively simple equipment and temperate condition, the purity height, and narrow diameter distribution, production cost is low.Chemical method prepares in the ball shape silver powder, AgNO ₃, Ag ₂CO ₃, [Ag (NH ₃) ₂] ⁺And other compounds of silver all can be used as initial reactant.What can be used as reducing agent has: formaldehyde, formates, hydrazine hydrate, glucose, polyalcohol, ferrous salt, ascorbic acid etc.At present, some chemical method prepares the ball shape silver powder technology of preparing, and since not enough to course of reaction control, cause silver powder nodularization rate low, and more non-spherical irregular particle appears, and the particle diameter wider distribution, to assemble seriously, complex process is difficult to satisfy industrialization and makes requirement.

Application number is that 99112631.9 Chinese patent literature adopts and adds ammoniacal liquor after silver nitrate and the dispersant and be made into silver ammino solution, mix with reductant solution by special shower nozzle then, dispersant is polyvinylpyrrolidone or alcamine compound, reducing agent is formaldehyde, hydrazine hydrate or hydroquinones, prepares the dense packing, spherical shaped silver of particle diameter at 0.1～3 μ m.This technology is comparatively complicated, need to adopt special shower nozzle, and part material has certain toxicity.

Application number is that 01118992.4 Chinese patent literature employing silver nitrate is silver-colored source, with (NH ₃) ₂CO ₃Or Na ₂CO ₃It is 1～7 to be made into silver-colored source solution that carbonate solution is regulated the liquor argenti nitratis ophthalmicus pH value, adopt modifier and reducing agent surfactant to form reductant solution, wherein modifier has oxalic acid, ammoniacal liquor, tartaric acid, glycerine, monoethanolamine, many hydramine, mercaptoethanol etc., surfactant is neopelex, TRITON-X100, sorbester p17, carboxymethyl cellulose, methylcellulose, polyethylene glycol, phosphoric acid fat salt, cationic starch, alginic acid, at 15～60 ℃, under the stirring condition, reducing agent is sneaked into silver-colored source solution, the preparation dense packing, spherical shaped silver.The silver powder of this method preparation has excellent roundness and sphericity, and particle diameter is adjustable continuously at 0.3-3 μ m, but its step is more, and condition is comparatively strict, and part reagent has toxicity.

Summary of the invention

The object of the present invention is to provide a kind of preparation method of ball shape silver powder, can access the ball shape silver powder of 0.5～5 μ m different-grain diameter.

A kind of wet-chemical of ball shape silver powder prepares method, may further comprise the steps:

Step a: respectively with liquor argenti nitratis ophthalmicus and FeSO ₄7H ₂O solution temperature adjustment to 0～20 ℃;

Step b: under agitation above-mentioned two kinds of solution are mixed, become yellow, generate silver powder, wherein silver nitrate and FeSO up to mixed solution ₄7H ₂The O mass ratio is 1: (2～8);

Step c: from mixed solution, be settled out silver powder, successively use deionized water and absolute ethanol washing, drying;

The mass concentration of described liquor argenti nitratis ophthalmicus is 1～100g/L, FeSO ₄7H ₂The mass concentration of O solution is 2～1000g/L.

Technique effect of the present invention is embodied in: 1. adopt silver nitrate as silver-colored source solution, ferrous sulfate is as reducing agent, and advantages of nontoxic raw materials need not the third chemical raw material; 2. technology is simple, and is easy to operate, good reproducibility, non-environmental-pollution; 3. can produce the spherical powder of 0.5～5 μ m different-grain diameter according to different customer requirements; 4. the ball shape silver powder of being produced has sphericity and comparatively coarse surface preferably, good dispersion, and the characteristics of purity height (〉=99.5%) are the ideal materials of producing various thick-film electronic slurries, as anisotropy conductiving glue/film.

Description of drawings

Fig. 1 is a process chart of the present invention;

The silver powder SEM that Fig. 2 makes for the embodiment of the invention one * 1000 shape appearance figures;

The silver powder SEM that Fig. 3 makes for the embodiment of the invention two * 2000 shape appearance figures;

The silver powder SEM that Fig. 4 makes for the embodiment of the invention three * 10000 shape appearance figures;

The silver powder SEM that Fig. 5 makes for the embodiment of the invention four * 2000 shape appearance figures;

Fig. 6 is silver powder internal component analysis energy spectrogram of the present invention;

The particle diameter of the dense packing, spherical shaped silver that Fig. 7 makes for embodiment two distributes.

The specific embodiment

Embodiment one: implement by technological process shown in Figure 1.Take by weighing the 1g silver nitrate and use the deionized water dissolving constant volume, take by weighing 4.4gFeSO in 50ml ₄7H ₂O uses the deionized water dissolving constant volume in 50ml.Both all are cooled to 6 ℃.Under stirring condition, both are mixed as early as possible fully then.No longer change until solution colour.Centrifugation spends deionised water 3 times, uses absolute ethanol washing then 2 times, gets silver powder 50 ℃ of following vacuum drying.Gained silver powder has sphericity preferably as shown in Figure 2, and average grain diameter is 3.0 μ m, good dispersion, particle diameter narrow distribution, purity height.

Embodiment two: take by weighing the 2g silver nitrate and use the deionized water dissolving constant volume in 50ml, take by weighing 8.8gFeSO ₄7H ₂O uses the deionized water dissolving constant volume in 50ml.Both all are cooled to 6 ℃.Under stirring condition, both are mixed as early as possible fully then.No longer change until solution colour.Adopt the silver powder precipitation of centrifugation, spend deionised water 3 times, use absolute ethanol washing then 2 times, obtain silver powder 50 ℃ of following vacuum drying to generating.Gained silver powder has sphericity preferably as shown in Figure 3, and average grain diameter is 3.5 μ m, good dispersion, particle diameter narrow distribution, purity height.The energy spectrum composition analysis of gained silver powder such as Fig. 6, its particle diameter distributes as Fig. 7.

Embodiment three: take by weighing the 1.2g silver nitrate and use the deionized water dissolving constant volume in 50ml, take by weighing 8.8gFeSO ₄7H ₂O uses the deionized water dissolving constant volume in 50ml.Both all are cooled to 20 ℃.Under stirring condition, both are mixed as early as possible fully then.No longer change until solution colour.Centrifugation precipitation silver powder spends deionised water 3 times, uses absolute ethanol washing then 3 times, gets silver powder 50 ℃ of following vacuum drying.Gained silver powder has sphericity preferably as shown in Figure 4, and average grain diameter is 1.7 μ m, good dispersion, particle diameter narrow distribution, purity height.

Embodiment four: preparation liquor argenti nitratis ophthalmicus and reductant solution: take by weighing the 1g silver nitrate and use the deionized water dissolving constant volume in 50ml, take by weighing 2.2gFeSO ₄7H ₂O uses the deionized water dissolving constant volume in 50ml.Both all are cooled to 10 ℃.Under stirring condition, both are mixed as early as possible fully then.No longer change until solution colour.After the natural subsidence, spend deionised water 3 times, use absolute ethanol washing then 2 times, get silver powder 50 ℃ of following vacuum drying.Gained silver powder has sphericity preferably as shown in Figure 5, and average grain diameter is 2.0 μ m, good dispersion, particle diameter narrow distribution, purity height.

Claims (1)

1. the wet chemical preparation method of a ball shape silver powder may further comprise the steps:

Step a: respectively with liquor argenti nitratis ophthalmicus and FeSO ₄7H ₂O solution temperature adjustment to 0～10 ℃;

Step b: under agitation above-mentioned two kinds of solution are mixed, become yellow, generate silver powder, wherein silver nitrate and FeSO up to mixed solution ₄7H ₂The O mass ratio is 1: (2～8);

Step c: from mixed solution, be settled out silver powder, successively use deionized water and absolute ethanol washing, drying;

The mass concentration of described liquor argenti nitratis ophthalmicus is 20～40g/L, FeSO ₄The mass concentration of solution is 44～176g/L.

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