KR20120082347A - Fine silver particles, method for producing same, conductive paste containing the fine silver particles, conductive film, and electronic device - Google Patents

Abstract

The alcohol solution of the silver nitrate amine complex adjusted by using one or more of silver nitrate and a boiling point of 200 degrees C or less amine as water solubility or water solubility is added and reduced in the water-alcohol mixed solvent which melt | dissolved ascorbic acid or erythorbic acid. After the precipitated silver particles were separated and washed, the average particle diameter (D _SEM ) was 30 to 100 nm by vacuum drying or vacuum freeze drying at a temperature of 30 ° C. or lower, and the degree of polycrystallization (average particle diameter (D _SEM )). Silver fine particles having a ratio (D _SEM / (D _X )) of crystalline diameter (D _X ) to 2.8 or more can be obtained, and the obtained silver fine particles have an average particle diameter of 30 to 100, which is suitable as a raw material such as a conductive paste capable of low temperature firing. nm is polycrystalline silver particles.

Description

Silver fine particles and a manufacturing method thereof, and a conductive paste, a conductive film and an electronic device containing the fine particles {FINE SILVER PARTICLES, METHOD FOR PRODUCING SAME, CONDUCTIVE PASTE CONTAINING THE FINE SILVER PARTICLES, CONDUCTIVE FILM, AND ELECTRONIC DEVICE}

TECHNICAL FIELD The present invention relates to silver fine particles having a polycrystallized average particle diameter of 30 to 100 nm, a method for producing the same, and a conductive paste, a conductive film, and an electronic device containing the silver fine particles, which are suitable as raw materials for a conductive composition capable of low temperature baking. .

Formation of the electrode and circuit pattern of an electronic device is performed by printing an electrode or a circuit pattern on a board | substrate using the electrically conductive paste containing a metal particle, and heating and baking to sinter the metal particle contained in an electrically conductive paste, In recent years, the heat firing temperature tends to be lowered.

For example, a flexible substrate made of polyimide is used as a mounting substrate of an electronic device because heating to about 300 ° C. is possible in general, but since it is excellent in heat resistance but expensive, in recent years, more inexpensive PET (polyethylene Terephthalate substrates and PEN (polyethylenenaphthalate) substrates are being considered as alternative materials. However, PET substrates and PEN substrates have low heat resistance as compared with flexible substrates made of polyimide, and it is necessary to carry out heat firing at 200 ° C or lower.

Moreover, if heat baking can be performed at a temperature lower than 200 degreeC, formation of the electrode and a circuit pattern to a board | substrate, such as a polycarbonate and paper, also becomes possible, and it is anticipated that the use of various electrode materials etc. will expand.

Silver microparticles | fine-particles of nanometer order are anticipated as a metal particle used as a raw material of the electrically conductive paste which can be baked at such low temperature. The reason for this is that when the size of the metal particles becomes nanometer order, the surface activity is increased and the melting point is much lower than that of the metal bulk, so that it is possible to sinter at a low temperature. In addition, among the metal particles, silver fine particles are low in resistance and inexpensive in comparison with other precious metals.

In addition, silver fine particles of nanometer order are expected to be used as a lead-free solder substitute material using properties not available in conventional solders, which can be sintered at a low temperature and maintain heat resistance once sintered.

Until now, silver fine particles of sub-micron size or less have been proposed as silver fine particles capable of low-temperature firing, and have an average particle diameter (D _TEM ) of 3 to 20 nm in which silver hexylamine is adsorbed on the surface (patent document 1) and the particle surface. Silver particle (patent document 2) whose average particle diameter (D _TEM ) covered with this organic protective agent is 50 nm or less, single crystallization degree (D _TEM / D _X ) is 2.0 or less, average particle diameter is 40-100 nm, and single crystallinity degree Silver fine particles having a (D _TEM / D _X ) of 1 to 5 (Patent Document 3), silver fine particles having an average particle diameter of 20 to 100 nm with an ammine complex of silver nitrate and an amine attached to the particle surface of 1 wt% or less (patent document) Document 4), precious particle fine particles having a mean particle diameter of less than 200 nm and a BET specific surface area of 1.0 m ² / g or more (Patent Document 5) coated with a surface treating agent, and an average particle diameter of less than 1% of soluble metals of 50% to a 100 nm, BET specific surface area of 6 to 25 m ² / g of the nano powder (especially Reference 6), there is known.

Patent Document 1: Japanese Patent Laid-Open No. 2009-161808 Patent Document 2: Japanese Patent Application Laid-Open No. 2007-19055 Patent Document 3: Japanese Patent Application Laid-Open No. 2006-183072 Patent Document 4: Japanese Patent Application Laid-Open No. 2009-144197 Patent Document 5: Japanese Patent Application Laid-Open No. 2004-43892 Patent Document 6: Japanese Patent Application Laid-Open No. 2005-530048

In order for silver fine particles to sinter at a low temperature, it is necessary for silver fine particles to be active, but in the case of silver fine particles having an average particle size of 20 nm or less disclosed in Patent Document 1 above, since the activity is too high and unstable, a large amount of organic matter It is necessary to coat with. In Patent Document 1, although hexylamine having a boiling point of about 130 ° C. is used as the coating material, even if a coating material having a relatively low boiling point is selected, it is difficult to completely remove a large amount of the coating. Moreover, in patent document 1, since the temperature of 50-60 degreeC is used in manufacturing silver fine particles, since the crystallite diameter of silver fine particles tends to become large, it becomes low as reactivity inside silver fine particles, and it is disadvantageous for low temperature sintering.

In addition, the above-mentioned Patent Document 2 describes silver particles having an average particle diameter (D _TEM ) of 50 nm or less and a single crystallinity (D _TEM / D _X ) of 2.0 or less, wherein the particle surface is covered with an organic protective agent. As described above, since (D _TEM / D _X ) is 2.0 or less and has a high degree of monocrystallization, the reactivity inside the silver fine particles becomes low, which is disadvantageous for low temperature sintering.

In addition, the above-mentioned Patent Document 3 describes silver fine particles having an average particle diameter of 40 to 100 nm and a single crystallinity (D _TEM / D _X ) of 1 to 5, but the temperature is around 40 ° C. in producing the silver fine particles. Since the crystallite size is adjusted, the crystallite diameter of the silver fine particles tends to increase. Therefore, it becomes low as reactivity inside silver fine particles, and becomes disadvantageous for low temperature sintering.

In addition, the above-mentioned Patent Document 4 describes silver fine particles having an average particle diameter of 20 to 100 nm in which an ammine complex of silver nitrate and an amine are attached to the particle surface of 1 wt% or less, but the reaction temperature in the reduction reaction is described. It is not considered, and since it tends to heat and dry at 40 degreeC, and a crystal grain diameter becomes large, it becomes low as reactivity inside silver fine particles, and it becomes disadvantageous for low temperature sintering.

In addition, although the above-mentioned patent document 5 describes the noble metal microparticles | fine-particles coat | covered with the surface treating agent and whose average particle diameter is less than 200 nm and BET specific surface area is 1.0 m <^2> / g or more, all the surface treating agents which coat | cover the particle surface are all Since it is a substance with a high boiling point, even in the Example of patent document 5, a surface treating agent remains in the heating condition of 200 degreeC, and it is difficult to use for the raw material of the electrically conductive paste for the purpose of low temperature sintering. In addition, since the BET specific surface area value is small with respect to the particle size and the surface activity is low, it is disadvantageous for low temperature sintering.

In addition, the above-mentioned Patent Document 6 describes nanoparticles having an average particle diameter of 50 to 100 nm and a BET specific surface area of 6 to 25 m ² / g containing less than 1% of a soluble metal. It is difficult to obtain the sintered compact which has the target high electroconductivity because the impurity metal which inhibits electroconductivity is contained in the sintered compact which contains the nanoparticle shown in patent document 6, and impairs electroconductivity. Moreover, since sintering is inhibited by the soluble metal which exists, it is difficult to sinter at low temperature.

Then, this invention makes it a technical subject to provide the polycrystallized silver fine particle whose average particle diameter is 30-100 nm suitable for the raw material of the electrically conductive paste which can be baked at low temperature.

The said technical subject can be achieved by the following this invention.

That is, the present invention, the average particle diameter (D _SEM) are from 30 to 100 nm, the degree of crystallinity [average particle diameter (D _SEM) and crystallite size (D _X) ratio (D _SEM / D _X) of] of 2.8 or more It is a silver fine particle characterized by the above-mentioned (this invention 1).

Moreover, this invention is the silver fine particle of this invention 1 whose change rate ((crystallite diameter of silver fine particle after heating for 30 minutes / crystallite diameter of silver fine particle before heating) x100) of the crystallite diameter by heating is 150% or more. (Invention 2).

Moreover, this invention is silver fine particles of this invention 1 or 2 in which the BET specific surface area value (SSA) (m <^2> / g) of silver fine particles and average particle diameter (D _SEM ) have a relationship of following formula (1) ( Invention 3).

Moreover, this invention is the water-alcohol mixture which dissolved the ascorbic acid or the erythorbic acid in the alcohol solution of the silver nitrate amine complex prepared using silver nitrate and one or more types of amine whose boiling point is 200 degrees C or less as water solubility or water solubility. The silver fine particles according to any one of the present inventions 1 to 3, wherein the silver fine particles are dried in a solvent and separated and washed, and the silver fine particles are dried by vacuum drying at a temperature of 30 ° C. or lower. It is a manufacturing method of (this invention 4).

Moreover, this invention is the manufacturing method of the silver fine particles of this invention 4 which performs all the processes until obtaining silver fine particles at the temperature of 30 degreeC or less (this invention 5).

Moreover, this invention is the electrically conductive paste containing the silver fine particles as described in any one of this invention 1-3 (this invention 6).

Moreover, this invention is an electroconductive film formed using the electrically conductive paste of this invention 6 (this invention 7).

Moreover, this invention is an electronic device which has a conductive film of this invention 7 (this invention 8).

Since the silver fine particles according to the present invention have an average particle diameter of 30 to 100 nm, there is no need to cover the surface with a large amount of organic matter like the silver fine particles of a single nano order, and since the polycrystallization degree is 2.8 or more, the activity inside the particles is reduced. Since it is high, since sintering of silver fine particles advances even at low temperature, it is suitable as raw materials, such as an electrically conductive paste which can be baked at low temperature.

Referring to the configuration of the present invention in more detail as follows.

First, the silver fine particle which concerns on this invention is described.

The silver fine particles according to the present invention have an average particle diameter (D _SEM ) of 30 to 100 nm, and a degree of polycrystallization (a ratio of average particle diameter (D _SEM ) to crystallite diameter (D _X ) of D _SEM / D _X ). It is characterized by more than 2.8.

The average particle diameter (D _SEM ) of the silver fine particles according to the present invention is 30 to 100 nm, preferably 40 to 100 nm, more preferably 50 to 100 nm. When the average particle diameter (D _SEM ) is less than 30 nm, the surface activity of the silver fine particles is high, and in order to maintain the fine particle diameter stably, it is not preferable to attach a large amount of organic matter and the like. Moreover, when average particle diameter (D _SEM ) exceeds 100 nm, since the surface activity which silver fine particles have becomes low and low temperature sintering property is impaired, it is unpreferable.

Is the crystallinity of the fine particles according to the invention [average particle diameter (D _SEM) and crystallite size (D _X) ratio (D _SEM / D _X) of] is at least 2.8, more preferably 3.0 or more, more preferably 3.2 or more. When the degree of polycrystallization is less than 2.8, the crystallite diameter in the silver fine particles becomes larger and closer to the single crystal, so that the reactivity in the silver fine particles decreases and the low-temperature sinterability is impaired. The upper limit of the said polycrystallization degree is about 10, More preferably, it is about 8.

The rate of change of crystallite diameter ((crystallite diameter of silver fine particles after heating for 30 minutes at 150 ° C./crystallite diameter of silver fine particles before heating) × 100) according to the present invention is 150% or more. When the rate of change of crystallite diameter is less than 150%, it is hard to say that it is excellent in low temperature sintering property. In this invention, even when it heats at 120 degreeC for 30 minutes, it is preferable that the rate of change of a crystalline diameter is 150% or more, and when changing to 100 degreeC for 30 minutes, it is more preferable that the rate of change of a crystalline diameter is 150% or more similarly.

The BET specific surface area value SSA of silver fine particles which concerns on this invention exists in the range represented by following formula (1). When BET specific surface area value SSA is smaller than the range of following formula (1), since a large amount of organic substance is processed on the surface of silver fine particles, since surface activity falls, it is difficult to obtain favorable low temperature sinterability.

The particle shape of the silver fine particles according to the present invention is preferably spherical or granular.

It is preferable that the impurity metal of silver fine particles which concerns on this invention is 500 ppm or less, More preferably, it is 200 ppm or less, More preferably, it is 100 ppm or less. When content of an impurity metal exceeds 500 ppm, since the impurity metal which inhibits electroconductivity is contained in the sintered compact obtained using this, it is difficult to obtain the target sintered compact which has high electroconductivity. Moreover, since sintering is inhibited by the impurity metal which exists, it is difficult to sinter at low temperature.

As long as the silver fine particle which concerns on this invention is a range which satisfy | fills the said characteristic, you may surface-treat. As a surface treating agent, alcohol or amine whose boiling point is 200 degrees C or less is preferable. As alcohol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, ethylene glycol, etc. can be used. As the amine, ammonia, methylamine, ethylamine, propylamine, butylamine, monoethanolamine and the like can be used.

When surface-treating silver fine particles, the amount of the amine and / or alcohol which is coat | covered or adhered is 1 weight% or less. When it exceeds 1 weight%, since low-temperature sintering property falls, it is unpreferable. More preferably, it is 0.9 weight% or less, More preferably, it is 0.8 weight% or less.

Next, the manufacturing method of the silver fine particles which concerns on this invention is described.

The silver fine particle which concerns on this invention dissolves ascorbic acid or erythorbic acid in the alcohol solution of the silver nitrate amine complex prepared using silver nitrate and one or more types of amine whose boiling point is 200 degrees C or less as water solubility or water solubility- It can be obtained by adding in an alcohol mixed solvent for reduction precipitation, separating and washing the obtained silver fine particles, and then drying the silver fine particles by vacuum drying at a temperature of 30 ° C. or lower. Moreover, it is preferable to carry out at the temperature of 30 degreeC or less in all the processes of silver fine particle manufacture. Thus, it becomes easy to maintain the polycrystallization degree of the defined silver fine particles.

As an amine whose boiling point is 200 degrees C or less as water-soluble or water-soluble in this invention, butylamine, propylamine, monoethanolamine, etc. can be used. Here, water solubility means mixing with water arbitrarily, and water solubility means having solubility to some extent in water.

As alcohol in this invention, what is compatible with water can be used. In consideration of the removal by vacuum drying at a temperature of 30 ° C. or lower in a subsequent step, an alcohol having a boiling point of 100 ° C. or lower is more preferable. Specifically, methanol, ethanol, propanol, isopropanol, etc. can be used, Preferably they are methanol and ethanol. You may use these alcohols individually or in mixture.

Hereinafter, although the example which uses butylamine as a representative of amine of water solubility or water solubility and a boiling point of 200 degrees C or less is described, it can be similarly prepared also by amines, such as propylamine and monoethanolamine.

In addition, the alcohol solution of the silver nitrate ammine complex prepared by using one or more of the above-mentioned silver nitrate and water-soluble or water-soluble amine having a boiling point of 200 ° C. or less is reduced with ascorbic acid or erythorbic acid in a water-alcohol mixed solvent. If the basic concept is characterized by the same, it is not limited to the following conditions. For example, the optimum volume ratio of the amount of methanol and the amount of water varies depending on the solubility in the solution of the amine used, the reaction vessel and the stirring mechanism.

First, an ammine complex of silver nitrate is formed in an alcohol solvent by silver nitrate and butylamine. The butylamine is preferably 2.0 to 2.5 equivalents, more preferably 2.0 to 2.3 equivalents to silver nitrate. When the amount of butylamine is less than 2.0 equivalents to silver nitrate, large particles tend to be produced.

Next, ascorbic acid or erythorbic acid as a reducing agent is dissolved in water, and then alcohol is added and mixed. Ascorbic acid or erythorbic acid is preferably 1.0 to 2.0 equivalents, more preferably 1.0 to 1.8 equivalents, based on silver nitrate. When ascorbic acid or erythorbic acid exceeds 2.0 equivalent, since the produced silver fine particles tend to aggregate, it is unpreferable.

Subsequently, the silver fine particles are precipitated by dropping an alcohol solution in which an ammine complex of silver nitrate is formed in a water-alcohol solution in which ascorbic acid or erythorbic acid is dissolved. The reaction temperature in a reduction reaction is 15-30 degreeC, More preferably, it is 18-30 degreeC. When reaction temperature exceeds 30 degreeC, crystallite diameter becomes large and the silver fine particle obtained becomes unpreferable because it approaches a single crystal.

After completion of the dropwise addition, stirring was continued for 1 hour or more, and then, the silver fine particles were settled by standing still, the supernatant was removed by decantation, and then the excess reducing agent, butylamine, silver nitrate, etc. were washed with alcohol and water.

The silver fine particles of this invention can be obtained by pulverizing by the usual method after wash | cleaning the silver fine particles at the temperature of 30 degreeC or less. When the drying temperature exceeds 30 ° C, the crystallite diameter becomes large and the silver fine particles obtained are close to the single crystal, which is not preferable.

Next, the electrically conductive paste containing silver fine particles which concerns on this invention is described.

The electrically conductive paste which concerns on this invention consists of silver fine particles and a solvent which concern on this invention, and you may mix | blend other components, such as binder resin, a hardening | curing agent, a dispersing agent, and a rheology regulator, as needed.

As binder resin, what is known in the said field can be used, For example, cellulose resin, such as ethyl cellulose and nitrocellulose, a polyester resin, a urethane modified polyester resin, an epoxy modified polyester resin, an acrylic modified polyester, etc. Various modified polyester resins, polyurethane resins, vinyl chloride-vinyl acetate copolymers, acrylic resins, epoxy resins, phenol resins, alkyd resins, butyral resins, polyvinyl alcohols, polyimides, polyamideimide, and the like. . These binder resins may be used alone or in combination of two or more.

As the solvent, those known in the art can be used, for example, tetradecane, toluene, xylene, ethylbenzene, diethylbenzene, isopropylbenzene, amylbenzene, p-cymene, tetralin and petroleum aromatic hydrocarbons Hydrocarbon solvents such as mixtures; Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-butyl ether, propylene glycol mono-t-butyl ether, diethylene glycol monoethyl ether, di Ether or glycol ether solvents such as ethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, and tripropylene glycol monomethyl ether; Glycol ester solvents such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate; Ketone solvents such as methyl isobutyl ketone and cyclohexanone; Terpene alcohols such as terpineol, linanol, geraniol and citronellol; alcohol solvents such as n-butanol, s-butanol and t-butanol; Glycol solvents such as ethylene glycol and diethylene glycol; (gamma) -butyrolactone, water, etc. are mentioned. A solvent can also be used individually or in combination of 2 or more types.

The content of the silver fine particles in the conductive paste varies depending on the application, but for example, in the case of a wiring forming application, the content is preferably as close to 100% by weight as possible.

The electrically conductive paste which concerns on this invention can be obtained by mixing and disperse | distributing each component using various kneaders and dispersers, such as a grinder, a pot mill, a three-axis roll mill, a rotary mixer, and a biaxial mixer. At this time, also in the process of obtaining a conductive paste, in order to maintain the polycrystallization degree of silver fine particles prescribed | regulated (so that a crystallite diameter may become large and the silver fine particles obtained may not approach a single crystal), each operation is performed at 30 degrees C or less. desirable.

The electrically conductive paste which concerns on this invention is applicable to various coating methods, such as screen printing, an inkjet method, gravure printing, transfer printing, roll coat, flow coat, spray coating, spin coat, dipping, braid coat, and plating.

Moreover, the electrically conductive paste which concerns on this invention is wiring formation materials, such as electrode formation of a flat panel display (FPD), a solar cell, organic EL, etc., wiring formation of an LSI board, and also the formation of a microscopic remains finder, via hole, and contact hole. It can be used as. It is also suitable as a wiring forming material and an electrode forming material on a flexible substrate, an IC card, and other substrates because of the low temperature firing, as well as the firing at high temperature, such as for forming internal electrodes of a multilayer ceramic capacitor or a laminated inductor. . Moreover, it can be used also for an electromagnetic shielding film, an infrared reflecting shield, etc. as a conductive film. In electronics mounting, it can also be used as a joining material for component mounting.

<Action>

Importantly in the present invention, the average particle diameter (D _SEM ) is 30 to 100 nm, and the degree of polycrystallization (ratio of average particle diameter (D _SEM ) and crystallite diameter (D _X ) (D _SEM / D _X )] is 2.8. The silver fine particles described above are capable of low-temperature firing.

This inventor considers as follows why the silver fine particle which concerns on this invention is excellent in low-temperature sintering property. That is, in order for the silver fine particles to be sintered at a low temperature, it is necessary for the silver fine particles to be active. However, since the activity is too high and unstable at an average particle size of 20 nm or less, it is usually necessary to coat them with a large amount of organic matter. Is usually a polymer and cannot be removed at low temperatures, making it difficult to lower the firing temperature. Although it is not necessary to coat | cover with a large amount of organic substance, 30-100 nm can be considered as a particle size with high surface activity as much as possible, In the case of silver particle of this particle size conventionally, surface active energy for sintering at low temperature is inadequate and it is low temperature. Firing was difficult. In the case of the silver fine particles according to the present invention, it is considered that the energy inside the particles is increased because the inside of the particles, that is, the silver fine particles are composed of polycrystals instead of single crystals, thereby allowing low-temperature firing.

Example

Next, the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. The evaluation method in a following example is shown.

The average particle diameter of silver fine particles takes the photograph of particle | grains using the scanning electron micrograph "S-4800" (made by HITACHI), The particle diameter is measured about 100 or more particle | grains using this photograph, The average value was computed and it was set as the average particle diameter (D _SEM ).

The specific surface area of silver fine particles was represented by the value measured by BET method using "Monosorb MS-11" (made by Canthachrome Co., Ltd.).

The crystallite diameter (D _X ) of the silver fine particles was half the value of the surface index (1,1,1) surface peak using the X-ray diffractometer "RINT2500" (manufactured by Rigaku Co., Ltd.) as a source of Kα rays of Cu. The width was obtained and the crystallite diameter was calculated by Scherrer's formula.

The polycrystallization degree of silver fine particles was shown by ratio (D _SEM / D _X ) of average particle diameter (D _SEM ) and crystallite diameter (D _X ).

The change rate (%) of the crystallite diameter by heating the silver fine particles is a value calculated according to Equation 1 using the crystallite diameter after heating the silver fine particles at 150 ° C. for 30 minutes and the crystallite diameter of the silver fine particles before heating. to be. Moreover, the change rate of the crystalline diameter was calculated | required similarly also when heating conditions were changed into 30 minutes at 120 degreeC, and 30 minutes at 100 degreeC.

&Quot; (1) &quot;

% Change of crystallite diameter = crystallite diameter of silver fine particles after heating / crystallite diameter of silver fine particles before heating * 100

The content of the impurity metal of the silver fine particles is measured using "Inductively Coupled Plasma Emission Spectroscopy SPS4000" (manufactured by Seiko Denshi Kogyo Co., Ltd.), and the total amount of the upper three elements among the elements having a high content of elements other than Ag Indicated.

The resistivity of an electroconductive coating film apply | coats the electrically conductive paste mentioned later on a polyester film, predryes at 120 degreeC, and then heat-cures at 150 degreeC for 30 minutes, and it is a 4-terminal electric resistance measuring apparatus "Lorista GP. / MCP-T610 "(manufactured by Daisha Instruments Co., Ltd.), and the specific resistance was calculated from the sheet resistance and the film thickness.

Example 1-1 Preparation of Silver Particles

40 g of silver nitrate and 200 mL of methanol were added to a 500 mL beaker, and then 37.9 g of n-butylamine was added and stirred while cooling in a water bath to prepare A solution. Separately, 62.2 g of erythorbic acid was added to a 2 L beaker, 400 mL of water was added thereto, stirred and dissolved, and 200 mL of methanol was added to prepare B solution.

Subsequently, A liquid was dripped at B liquid over 1 hour 20 minutes, stirring B liquid. During the dropping, the reaction temperature was adjusted to maintain 25 ° C. After completion of dropping, the mixture was stirred for 14 hours, and then allowed to stand for 30 minutes to settle the solid. The supernatant was removed by decantation, suction filtered using filter paper, and then washed and filtered using methanol and pure water. The obtained silver fine particles solid was dried at 30 ° C. for 6 hours in a vacuum dryer, and then pulverized by the usual method to obtain the silver fine particles of Example 1-1. In addition, the temperature in each said process was adjusted not to exceed 30 degreeC.

The average particle diameter (D _SEM ) of the obtained silver fine particles was 82.5 nm, the crystallite diameter (D _X ) was 21.3 nm, the polycrystalline degree (D _SEM / D _X ) was 3.9, and the BET specific surface area value was 5.3 m ² / g, The change rate of diameter (150 degreeC x 30 minutes) was 245%, and content of soluble metal was less than 50 ppm.

Example 2-1 Preparation of Conductive Paste

Premixed with diethylene glycol monoethyl ether so that the content of the silver fine particles in the electrically conductive paste was 11.0 parts by weight of the polyester resin, 1.4 parts by weight of the curing agent, and the silver fine particles in the conductive paste based on 100 parts by weight of the silver fine particles of the present invention. Thereafter, the mixture was kneaded and dispersed in a uniform manner using a triaxial roll to obtain an electrically conductive paste. In addition, the temperature of each said process for obtaining an electrically conductive paste was adjusted so that it might not exceed 30 degreeC.

The specific resistance of the obtained electroconductive coating film was 5.5x10 <^-5> ohm-cm.

According to Example 1-1 and Example 2-1, silver fine particles and an electrically conductive paste were produced. The various characteristics of each manufacturing conditions, the obtained silver fine particle powder, and an electrically conductive paste are shown.

Examples 1-2 to 1-4 and Comparative Examples 1-1 to 1-2:

Silver fine particles were obtained by changing the production | generation conditions of silver fine particles in various ways.

Table 1 shows the production conditions at this time, and Table 2 shows the properties of the silver fine particles obtained.

 [Table 1]

 [Table 2]

<Production of Conductive Paint>

Examples 2-2 to 2-4 and Comparative Examples 2-1 to 2-2:

Except having changed the kind of silver fine particles in various ways, the electrically conductive coating material and the conductive film were produced according to the manufacturing method of the electrically conductive paint of the said Example 2-1.

The manufacturing conditions at this time and the various characteristics of the obtained electroconductive coating film are shown in Table 3.

 [Table 3]

Industrial availability

Since the silver fine particles according to the present invention have an average particle diameter of 30 to 100 nm, it is not necessary to cover the surface with a large amount of organic matter like the silver fine particles of a single nano order, and since the polycrystallization degree is 2.8 or more, the activity inside the particles is reduced. Since sintering of silver fine particles advances even at high temperature, it is suitable as raw materials, such as an electrically conductive paste which can be baked at low temperature.

Claims (8)

The average particle diameter (D _SEM) are from 30 to 100 nm, the crystallinity is fine particles of not less than [average particle diameter (D _SEM) and a crystallite size ratio (D _SEM / D _X) of (D _X)] 2.8 . The silver fine particles according to claim 1, wherein the rate of change of the crystallite diameter by heating ((crystallite diameter of silver fine particles after heating for 30 minutes at 150 ° C./crystallite diameter of silver fine particles before heating) × 100) is 150% or more. The silver fine particles according to claim 1 or 2, wherein the BET specific surface area value (SSA) (m ² / g) and the average particle diameter (D _SEM ) of the silver fine particles have a relationship of the following formula (1).

The alcohol solution of the silver nitrate amine complex prepared in any one of Claims 1-3 by using one or more types of silver nitrate and a boiling point of 200 degrees C or less amine as water solubility or water solubility is ascorbic acid or erythorbic acid. A method for producing a silver fine particles, characterized in that the fine particles are dissolved in a water-alcohol mixed solvent, and the precipitated particles are reduced and precipitated. The obtained fine particles are separated and washed, and the silver fine particles are dried by vacuum drying at a temperature of 30 ° C. or lower. The manufacturing method of silver fine particles of Claim 4 which performs all the processes until obtaining silver fine particles at the temperature of 30 degreeC or less. The electrically conductive paste containing the silver fine particle of any one of Claims 1-3. The conductive film formed using the electrically conductive paste of Claim 6. The electronic device which has a conductive film of Claim 7.