KR101796339B1 - Electrically conductive copper particles, process for producing electrically conductive copper particles, composition for forming electrically conductive body, and base having electrically conductive body attached thereto - Google Patents

Abstract

The present invention relates to a conductive copper particle containing a chlorine atom in an amount of 50 to 1000 mass ppm relative to the total mass of the particles and the chlorine atom being present in a water-insoluble form.

Description

TECHNICAL FIELD [0001] The present invention relates to a conductive copper particle and a method for producing the conductive copper particle, a composition for forming a conductive material, and a substrate on which a conductive material is formed. BACKGROUND OF THE INVENTION [0001] THERETO}

TECHNICAL FIELD The present invention relates to a conductive copper particle and a method for producing the conductive copper particle, a composition for forming a conductor, and a substrate on which a conductor is formed.

As a method for producing a substrate on which a conductor having a conductor film of a desired wiring pattern is formed, such as a printed circuit board, there is known a method in which a silver paste containing silver particles is coated on a substrate in a desired wiring pattern and cured. However, the silver conductor film tends to cause a short circuit due to ion migration. Therefore, from the viewpoint of reliability of electronic equipment, it has been studied to form a conductor film by using copper paste instead of silver paste. However, the copper particles are easily oxidized and an oxide film is likely to be formed on the surface. Therefore, the conductor film using the copper particles tends to have a high volume resistivity, and the change with time is large.

The following methods (1) to (3) are known as methods for producing conductive copper particles that form conductor films with low volume resistivity.

(1) A method in which a conductive powder (powder) made of copper or a copper alloy is treated with an aqueous solution containing an acid and a reducing agent and an alkali metal salt of a fatty acid having 8 or more carbon atoms (Patent Document 1).

(2) A method of precipitating hydrogenated copper fine particles by adding hypophosphorous acid to a copper salt aqueous solution and thermally decomposing the hydrogenated copper fine particles to obtain copper fine particles (Patent Document 2).

(3) Copper ions are contained in a solution containing 0.05 mol or more (1250 mass ppm or more) of chloride ion with respect to the copper ions and reduced to a pH of 10 to 12.5 to obtain copper particles having irregularities on the surface (Patent Document 3).

Japanese Patent Application Laid-Open No. 2007-184143 Japanese Unexamined Patent Application Publication No. 2-294417 Japanese Patent Application Laid-Open No. 2007-169770

However, although the conductor film using the copper particles produced by the method (1) has excellent conductivity immediately after the film formation, the volume resistivity greatly increases due to preservation at room temperature and in air, so that it can not be used for wiring of electronic devices.

According to the method (2), particles obtained by coagulating copper hydride fine particles can be obtained. However, when particles made by this method are used to form a conductive film, the conductivity is insufficient and the volume resistivity is increased by preservation at room temperature and air .

The conductor film using the copper particles produced by the method (3) has a large volume resistivity even after the film formation and its volume resistivity increases with time, so that it can not be used for wiring of electronic devices.

The present invention relates to a method for producing conductive copper particles and conductive copper particles capable of forming a conductive film having a low volume resistivity and a small change with time, a composition for forming an electric conductor containing the conductive copper particles, And a conductor having a conductor film formed by the composition for forming a conductor.

The conductive copper particles of the present invention contain a chlorine atom in an amount of 50 to 1000 mass ppm relative to the total mass of the particles, and the chlorine atom exists in a form of water-insoluble.

The conductive copper particles of the present invention preferably have an average particle size of 0.01 to 20 탆.

The composition for forming an electric conductor of the present invention contains the conductive copper particles of the present invention and a solvent. The composition for forming a conductor of the present invention preferably contains a resin binder.

The substrate on which the conductor of the present invention is formed has a substrate and a conductor film formed on the substrate by the composition for forming a conductor of the present invention.

A method of producing conductive copper particles according to the present invention is a method having a step of reducing at least one of copper particles and copper (II) ions in a reaction system containing chloride ions and having a pH of 3 or less and an oxidation-reduction potential of 220 ㎷ or less .

By using the conductive copper particles of the present invention, a conductor film having a low volume resistivity and a small change with time can be formed.

Further, according to the method for producing conductive copper particles of the present invention, conductive copper particles capable of forming a conductor film having a low volume resistivity and a small change with time are obtained.

In addition, the composition for forming a conductor of the present invention contains the conductive copper particles of the present invention, so that a conductor film having a low volume resistivity and a small change with time can be formed.

In addition, the base material on which the conductor of the present invention is formed has a low volume resistivity of the conductor film and a small change with time.

≪ Conductive copper particles &

By using the conductive copper particles of the present invention, a conductor film having a low volume resistivity and a small increase in volume resistivity over time can be formed. The reason why the conductive film having the above effect can be formed is not necessarily clear, but is estimated as follows.

The conductive copper particles of the present invention contain chlorine atoms present in a water-insoluble form. In the present specification, the presence of the chlorine atom in the form of water-insoluble means that the concentration of the chloride ion measured by a measuring method described later becomes 10 mass ppm or less.

In order to obtain the conductive copper particles of the present invention, copper (II) ions (divalent copper ions) are reduced, and it is considered that they pass through copper (I) ions (monovalent copper ions) in the process. When a copper (I) ion is generated, when a suitable amount of chloride ion as a monovalent anion is present in the vicinity thereof, it is considered that both react quickly and copper (I) chloride is formed on the surface of the conductive copper particle. Therefore, it is considered that oxidation of the surface of the conductive copper particles is suppressed and a low volume resistivity is obtained. Further, the copper (I) chloride has a very low solubility in water and has a low affinity with water, so that the deterioration due to moisture in the air is small. Therefore, it is considered that the excellent effect that the increase of the volume resistivity can be suppressed for a long time even after the substrate having the conductor is formed is obtained.

As described above, in the conductive copper particles of the present invention, it is considered that chlorine atoms exist in a form in which solubility in water is extremely low. However, since it is difficult to identify copper (I) chloride in the conductive copper particles, it is defined that the chloride ion concentration measured by a measurement method described later becomes 10 mass ppm or less, thereby being insoluble.

The content of chlorine atoms in the conductive copper particles is preferably 50 to 1000 mass ppm, more preferably 80 to 300 mass ppm with respect to the total mass of the conductive copper particles. When the content of the chlorine atom is not lower than the lower limit, the progress of surface oxidation of the copper particles can be suppressed. When the content of chlorine atoms is not more than the upper limit value, a conductor film having a small volume resistivity can be formed. The content of chlorine atoms in the conductive copper particles is measured by fluorescent X-ray analysis.

(Measurement method)

1. The content of chlorine atoms in the conductive copper particles is measured by fluorescent X-ray analysis.

2. Assuming that all the chlorine atoms contained in the conductive copper particles are eluted into the distilled water, the amount of the conductive copper particles having a chloride ion concentration of 100 mass ppm contained in the distilled water is immersed in distilled water.

3. The distilled water immersed in the conductive copper particles was stirred at 1000 rpm for 5 seconds using a test tube mixer (HM-01, manufactured by Asuzen Co., Ltd.) at 20 캜, and then the chloride ion concentration eluted in the distilled water was measured . Here, distilled water used is distilled water whose dissolved oxygen concentration is adjusted to 1 mass ppm or less.

In addition, the concentration of dissolved oxygen is set to 1 mass ppm or less because copper chloride (I) (monovalent copper) present in the conductive copper particles is converted into copper (II) chloride (bivalent copper) by the influence of oxidation by dissolved oxygen, As shown in FIG.

The surface oxygen amount expressed by the ratio of the surface oxygen concentration (unit: atom%) to the surface copper concentration (unit: atom%) of the conductive copper particles is preferably 0.5 or less, more preferably 0.3 or less. If the surface oxygen amount is less than the upper limit value, the contact resistance between the conductive copper particles becomes smaller, and the conductivity of the conductive film is improved.

Also, the surface oxygen concentration and the surface copper concentration of the conductive copper particles are obtained by X-ray photoelectron spectroscopy. The measurement is carried out for a range from the particle surface toward the center to a depth of about 3 nm. If the measurement is made for this range, the state of the particle surface can be grasped sufficiently.

The form of the conductive copper particles of the present invention is not particularly limited. The conductive copper particles of the present invention include, for example, the following conductive copper particles (A) to (E).

(A) Copper particles having an average particle diameter of 1 占 퐉 or more as primary particles containing chlorine atoms in a water-insoluble form.

(B) a primary particle containing a chlorine atom in a water-insoluble form and having an average particle diameter of 20 to 50 nm, as secondary particles containing a chlorine atom in a water-insoluble form on the surface of copper particles having an average particle diameter of 1 m or more, Copper composite particles with hydrogenated copper fine particles of 350 nm.

(C) Secondary particles containing chlorine atoms in a water-insoluble form and having an average particle diameter of 10 nm to 1 탆.

(D) a primary particle containing a chlorine atom in a water-insoluble form and having an average particle diameter of 20 to 50 nm as a secondary particle containing a chlorine atom in a water-insoluble form on the surface of copper particles having an average particle diameter of 1 m or more, Copper composite particles with copper fine particles attached at 350 nm.

(E) Copper microparticles having an average particle size of 10 nm to 1 μm, as secondary particles containing chlorine atoms in a water-insoluble form.

The conductive copper particles (B) and the conductive copper particles (D) are conductive copper particles comprising a combination of primary particles and secondary particles, and the conductive copper particles (A), (C) Or conductive particles made of only secondary particles.

Hydrogenated copper fine particles are converted into copper metal by heating so as to become copper fine particles. That is, the conductive copper particles (B) become conductive copper particles (D) by heating. Further, the conductive copper particles (C) become conductive copper particles (E) by heating.

The conductive copper particles of the present invention are preferably coated with an organic substance on the surface thereof for the purpose of preventing oxidation and improving fluidity of the composition for forming a conductor. The term " coating " includes not only the case where the organic material covers the entire surface of the conductive copper particles but also the case where the organic material covers the entire surface of the conductive copper particles. Further, it includes not only the case where the organic material is bonded to the surface of the conductive copper particles but also the case where the organic material is coordinated.

Examples of the organic substances include carboxylic acids, amines, imidazole-based compounds, and triazole-based compounds.

Examples of the carboxylic acid include oleic acid, stearic acid, myristic acid, dodecanoic acid, decanoic acid, octylic acid, octanoic acid, hexanoic acid, benzoic acid, salicylic acid and abietic acid.

Examples of the amine include oleylamine, stearylamine, myristylamine, dodecylamine, decylamine, octylamine, hexylamine and aniline.

As the organic material, when preparing a composition for forming a conductor containing a resin binder together with conductive copper particles, a carboxylic acid is preferable and oleic acid, salicylic acid, and abietic acid are preferable from the viewpoint of wettability of the conductive copper particles and the resin. More preferable. The wettability is the affinity between the particle surface and the resin by changing the interface energy.

The average particle diameter of the conductive copper particles of the present invention is preferably 0.01 to 20 占 퐉, and may be suitably adjusted within this range depending on the shape of the conductive copper particles. When the conductive copper particles contain primary particles, the average particle diameter is more preferably 1 to 10 mu m. When the conductive copper particles are composed only of secondary particles, the average particle diameter is preferably 0.01 to 1 占 퐉, and particularly preferably 0.02 to 0.4 占 퐉. If the average particle diameter of the conductive copper particles is not lower than the lower limit value described above, the flowability of the composition for forming a conductor containing the conductive copper particles is improved. When the average particle diameter of the conductive copper particles is not more than the upper limit, the fine wiring can be easily produced.

The average particle diameter in the present specification can be obtained as follows according to the shape of the conductive copper particles. The average primary particle size of the primary particles is calculated by measuring the particle diameters of 100 randomly selected particles in an image of a scanning electron microscope (hereinafter referred to as " SEM ") and averaging the particle diameters. The secondary particles are calculated by measuring the particle diameters of 100 particles randomly selected from images of a transmission electron microscope (hereinafter referred to as " TEM ") and averaging the particle diameters of the particles.

When the copper particles are not spherical, when the primary particles are used, the average value of the major and minor diameters of the copper particles is taken as the particle diameter. When the particles are secondary particles, the average value of the long diameter of the secondary particles and the short diameter of the secondary particles is taken as the particle diameter.

In the case of the conductive copper particles (B), the whole of the conductive copper particles (B) including the copper particles as the primary particles and the copper particles as the secondary particles attached to the copper particles were observed by SEM, The average value of the long and short diameters including the car particles is taken as the particle diameter. Similarly, in the case of the conductive copper particles (D), the entire conductive copper particles (D) including the copper particles as the primary particles and the copper particles as the secondary particles attached to the copper particles are observed by SEM, The average value of the long and short diameters including the particle is taken as the particle diameter.

<Method for producing conductive copper particles>

The conductive copper particles of the present invention are produced by a production method having a step of reducing at least one of copper particles and copper (II) ions in a reaction system containing chloride ions and having a pH of 3 or less and an oxidation-reduction potential of 220 ㎷ or less can do. Hereinafter, a specific production method will be described for each type of conductive copper particles to be produced.

(Method for producing conductive copper particles (A)) [

Examples of the method for producing the conductive copper particles (A) include a method having the following steps (α-1) and (α-2).

(hereinafter referred to as &quot; copper particles (a1) &quot;), which are primary particles of the (? -1) primary particles are dispersed in a dispersion medium, chloride ions are contained therein and the pH is 3 or less and the redox potential is 220 ㎷ or less (Hereinafter referred to as &quot; reaction system (a) &quot;) to obtain the conductive copper particles (A).

and separating the conductive copper particles (A) from the (? -2) reaction system (?).

Step (α-1):

A method of dispersing copper particles (a1) in a dispersion medium, adding a compound dissolved in the dispersion medium to produce chloride ions, adjusting the pH to 3 or less and adding a reducing agent to form a reaction system (a) Reduce. Here, during the reduction reaction, the redox potential of the reaction system (?) Is adjusted to be 220 ㎷ or less. The surface of the copper particles (a1) is usually oxidized to form an oxide film composed of copper oxide. In the reaction system (?) Of the step (? -1), copper oxide of the oxide film of the copper particle (a1) is reduced. The reaction system (?) May be formed by adding a compound which is dissolved in the dispersion medium to generate chloride ions, the pH is adjusted to 3 or less, the reducing agent is added, and then the copper particles (a1) are dispersed. Again, during the reduction reaction, the redox potential of the reaction system (?) Is adjusted to be 220 ㎷ or less.

Examples of the copper particles (a1) include well-known metal copper particles generally used for a composition for forming a conductor called a copper paste. These metallic copper particles are primary particles. The particle shape of the copper particles (a1) may be spherical, or may be in the form of a plate or a scaly powder.

Since the surface of copper particles is easily oxidized, commercially available copper particles are generally surface-treated with long-chain carboxylic acids such as stearic acid, oleic acid and myristic acid for the purpose of preventing oxidation of the surface. Copper particles surface-treated with a long-chain carboxylic acid tend to flocculate in a high-polarity dispersion medium such as water described later because the surface is hydrophobic. Therefore, in the case of using the copper particles surface-treated with the long-chain carboxylic acid, it is preferable to remove the long-chain carboxylic acid on the surface before the step (? -1). Removal of the long chain carboxylic acid on the surface can be carried out by treating the copper particles with a degreasing agent or by heat treatment in an alkaline aqueous solution.

As described later, the medium of the copper particles (a1) uses a medium having a high polarity such as water or a mixed medium of water and alcohols. Copper particles pretreated with a dispersant are preferred as the copper particles (a1) from the viewpoints of improving dispersibility of the copper particles (a1) to these high-polarity dispersion media and inhibiting coagulation of the copper particles. The dispersant is supported on the surface of the copper particles to hydrophilize the surface thereof. Copper particles surface-treated with a long-chain carboxylic acid can be obtained by pretreatment with a dispersant.

As the dispersing agent, various water-soluble compounds having chemical adsorption to copper particles can be used. Examples of the water-soluble compounds include mono-chain aliphatic carboxylic acids, water-soluble polymer compounds, and chelating agents.

Examples of the monocyclic aliphatic carboxylic acids include aliphatic monocarboxylic acids such as aliphatic monocarboxylic acids having 6 or less carbon atoms, aliphatic hydroxymonocarboxylic acids and aliphatic amino acids; Aliphatic polycarboxylic acids such as aliphatic polycarboxylic acids and aliphatic hydroxycarboxylic acids having 10 or less carbon atoms are more preferable.

Examples of the water-soluble polymer compound include polyvinyl alcohol, polyacrylic acid, polyvinylpyrrolidone, hydroxypropylcellulose, propylcellulose, ethylcellulose and the like.

Examples of the chelating agent include ethylenediaminetetraacetic acid, iminodiacetacetic acid, and the like.

As the dispersing agent, monocyclic aliphatic carboxylic acids are preferable, and aliphatic polycarboxylic acids having 8 or less carbon atoms such as glycine, alanine, citric acid, citric acid anhydride, malic acid, maleic acid and malonic acid are more preferable, and malic acid, , And tricarboxylic acids such as citric acid are particularly preferable.

The pretreatment can be carried out by dissolving the dispersant in a solvent such as water, adding copper particles into this solution, and stirring. Thereby, the dispersant is bonded to the surface of the copper particles. The pretreatment is preferably carried out by replacing the inside of the processing vessel with an inert gas from the viewpoint of suppressing the oxidation of the surface of the copper particles. As the inert gas, nitrogen gas, argon gas, or the like can be used. After the pretreatment, the solvent is removed and, if necessary, washed with water or the like to obtain copper particles whose surface has been hydrophilized by the pretreatment.

Pretreatment can also be carried out under heating. By performing the pretreatment under heating, the processing speed is improved. The heating temperature is preferably 50 占 폚 or higher and the boiling point of the solvent such as water (when the low boiling point dispersant is used, its boiling point or lower) is preferable. The heating time is preferably 5 minutes or longer. Further, since the heating for a long time is not economical, the heating time is preferably 3 hours or less.

The amount of the dispersant used in the pretreatment is preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the copper particles before the pretreatment.

The average particle size (average primary particle size) of the copper particles (a1) is preferably 1 to 20 占 퐉. As a result, the conductive copper particles (A) having an average particle size (average primary particle size) of 1 to 20 μm are easily obtained.

The concentration of the copper particles (a1) in the reaction system (?) (100 mass%) is preferably from 0.1 to 50 mass%. When the concentration of the copper particles (a1) is 0.1 mass% or more, the amount of the dispersion medium to be used can be suppressed and the production efficiency of the conductive copper particles (A) is also improved. When the concentration of the copper particles (a1) is 50 mass% or less, the influence of the coagulation of the copper particles (a1) becomes smaller, so that the yield of the conductive copper particles (A) tends to increase.

As the dispersion medium, a medium containing alcohols such as methanol, ethanol, 2-propanol, and ethylene glycol as main components can be used, and water is particularly preferable. In addition, when water is used as the main component, it means that water is contained in an amount of 70% by mass or more in 100% by mass of the dispersion medium.

The concentration of the chloride ion in the reaction system (?) Is preferably 5 to 100 mass ppm, more preferably 10 to 50 mass ppm, relative to the total mass of the reaction system (?). If the concentration of the chloride ion is not lower than the lower limit, an appropriate amount of chloride ion is present on the surface of the copper particle (a1) in the course of the reduction reaction, so that copper chloride (I) (A) is easily obtained. When the concentration of the chloride ion is not more than the upper limit, the amount of copper (I) chloride in the conductive copper particles (A) is excessively large, so that deterioration of the conductivity is easily suppressed.

The concentration of the chloride ion can be adjusted by controlling the addition amount of the compound which is dissolved in the dispersion medium of the copper particle (a1) to generate the chloride ion. As the compound which generates chloride ion, hydrochloric acid, sodium chloride, potassium chloride, copper (II) chloride and the like can be suitably used.

The pH of the reaction system (?) Is 3 or less, preferably 0.5 to 3, more preferably 0.5 to 2. When the pH of the reaction system (?) Is 3 or less, the reduction of the oxide film on the surface of the copper particles (a1) is smoothly performed. It is also known that a stable region of copper (I) chloride exists at a specific redox potential in a region of low pH such as pH 3 or less (Nakano, Hiroaki et al., Journal of MMIJ, No. 123, Page 38). Thus, in the step (α-1), copper oxide (I) is generated on the surface of the copper particle (a1) when the oxide film is reduced, and consequently, the conductive copper particles A) is considered to be obtained.

In addition, when the pH is 0.5 or more, it is easy to suppress excessive elution of copper (II) ions from the copper particles, and the surface of the copper particles (a1) can be smoothly modified smoothly.

The pH of the reaction system (?) Is adjusted by a pH adjuster.

As the pH adjusting agent, an acid can be used. The acid of the pH adjuster is preferably a carboxylic acid soluble in water or alcohols such as formic acid, citric acid, maleic acid, malonic acid, acetic acid, and propionic acid. The carboxylic acid adsorbed on the surface of the copper particles may remain on the surface of the conductive copper particles (A) after the reduction treatment. The remaining carboxylic acid can protect the surface of the conductive copper particles (A) and thus can be expected to have an effect of inhibiting oxidation. As the acid of the pH adjusting agent, formic acid is particularly preferable among the above carboxylic acids. Since formic acid is a compound having an aldehyde structure (-CHO), it has a reducing property. Therefore, when formic acid remains on the surface of the conductive copper particles (A) after the reduction treatment, the effect of suppressing the oxidation of the surface of the conductive copper particles (A) is further enhanced. As a result, The rise of the volume resistivity of the film can be suppressed easily.

As the acid of the pH adjuster, sulfuric acid, nitric acid, hydrochloric acid, etc. may be used in addition to the carboxylic acid soluble in the above-mentioned water or alcohols. The hydrochloric acid can simultaneously adjust the concentration of the chloride ion and the pH. When the pH of the dispersion liquid in which the copper particles (a1) are dispersed in the dispersion medium and a compound (hydrochloric acid or the like) for producing chloride ions is added is 3 or less, the dispersion can be used as it is for reduction treatment.

Further, when the pH is excessively lowered by the acid, the pH can be adjusted by using a base as a pH adjusting agent.

The oxidation-reduction potential (ORP) of the reaction system (?) Is 220 ㎷ or less, preferably 150 to 220 하고, and particularly preferably 180 to 220.. When the ORP is 220 ㎷ or less, the reducing effect of the oxide film on the surface of the copper particle (a1) becomes large, and the surface modification proceeds sufficiently. If the ORP exceeds 220 ㎷, the surface modification becomes insufficient, and not only the initial volume resistivity becomes large, but also the change with time in the volume resistivity becomes large. In the present specification, the ORP is obtained as a potential difference with respect to the potential of the standard hydrogen electrode (SHE).

The ORP of the reaction system (?) Can be controlled depending on the kind of the reducing agent used. It can also be controlled to some extent by a reducing acid such as formic acid.

Examples of the reducing agent include hypophosphorous acid compounds, amine borane compounds, and hydrides.

Examples of the hypophosphite compound include hypophosphorous acid, hypophosphite, and the like.

Examples of the amine borane compound include dimethylamine borane and the like.

Examples of the hydride include borohydride salts and the like.

As the reducing agent, hypophosphorous acid, hypophosphite, dimethylamine borane, or borohydride salt are preferable, and hypophosphorous acid or hypophosphite is particularly preferable.

The amount of the reducing agent to be used is preferably at least 1 mol, and more preferably 1.2 to 10 mol, relative to the entire copper particles (a1). When the amount of the reducing agent used is one mole or more relative to the total amount of the copper particles (a1), the reducing agent is excessively excessive with respect to the copper on the surface of the copper particles (a1), and the reduction tends to proceed sufficiently. When the amount of the reducing agent used is less than 10 times by mole based on the total amount of the copper particles (a1), it is economically advantageous, and the amount of the decomposition product of the reducing agent is reduced, thereby facilitating its removal.

The reduction reaction may be initiated by dispersing the copper particles (a1) in a dispersion medium, adding a reducing agent to the dispersion in which the concentration and pH of the chloride ion are adjusted, adjusting the concentration and pH of the chloride ion, The particles (a1) may be dispersed and started.

The reaction temperature of the reduction reaction is preferably 5 to 60 占 폚, more preferably 35 to 50 占 폚. When the reaction temperature is not lower than the lower limit, the reduction reaction is likely to proceed. If the reaction temperature is lower than the upper limit, the influence of the change in the concentration of the reaction system (?) Due to evaporation of the dispersion medium is small.

After completion of the reduction reaction, the obtained conductive copper particles (A) are separated from the reaction system (?), Washed with water or the like if necessary, and then dried to obtain a powder of the conductive copper particles (A). Since the by-products such as the decomposition product of the reducing agent are soluble in the dispersion medium, they can be separated from the conductive copper particles (A) by a method such as filtration and centrifugation.

(Method for producing conductive copper particles (B)) [

Examples of the method for producing the conductive copper particles (B) include a method having the following steps (? -1) to (? -3).

(II) ion is reduced in a reaction system (hereinafter referred to as &quot; reaction system (?) &quot;) containing a copper (II) ion and a chloride ion and having a pH of 3 or less and an ORP of 220 ㎷ or less (Hereinafter referred to as &quot; hydrogenated copper microparticles (b1) &quot;) having an average particle size of 20 to 350 nm as the secondary particles.

(hereinafter referred to as "copper particles (b2)") were added to the reaction system (β) before, during, or after the formation of the copper (β-2) copper hydride fine particles (b1) (Conductive copper particles (B)) in which hydrogenated copper microparticles (b1) are attached to the surface of the particles (b2).

(? -3) A step of separating the conductive copper particles (B) from the reaction system (?).

Process (? -1):

A water-soluble copper compound is dissolved in a solvent, a compound which is dissolved in the solvent to generate chloride ion is added, and a reducing agent whose oxidation-reduction potential is 220 ㎷ or less is added at pH 3 or lower to form a reaction system do. In the reaction system (?), Copper (II) ions are reduced by a reducing agent, and copper hydride fine particles (b1), which are secondary particles containing chlorine atoms in a water-insoluble form, are produced. The copper hydride copper fine particles (b1) are preferably agglomerated secondary particles of 20 to 350 nm.

Examples of the water-soluble copper compound include copper sulfate (II), copper (II) nitrate, copper (II) formate, copper (II) acetate, copper (II) chloride, copper (II) bromide and copper .

The solvent is not particularly limited as long as the water-soluble copper compound dissolves and is inert to the reducing agent described later. A mixed solvent of water and water and an alcohol (ethanol, isopropyl alcohol, etc.) is preferable, and water is particularly preferable Do.

The concentration of the water-soluble copper compound in the reaction system (?) (100 mass%) is preferably from 0.1 to 30 mass%. When the concentration of the water-soluble copper compound is 0.1% by mass or more, the amount of the solvent used can be suppressed and the production efficiency of the copperhydroxide microparticles (b1) is improved. When the concentration of the water-soluble copper compound is 30 mass% or less, the yield of the copper hydride fine particles (b1) is improved.

The concentration of the chloride ion in the reaction system (β) is preferably from 5 to 100 mass ppm, more preferably from 10 to 50 mass ppm, based on the total mass of the reaction system (β), for the same reason as the reaction system (α). The concentration of the chloride ion can be adjusted by using a compound which is dissolved in the dispersion medium to produce chloride ions. As the compound which generates chloride ion, hydrochloric acid, sodium chloride, potassium chloride, copper (II) chloride and the like can be suitably used.

The pH of the reaction system (?) Should be 3 or less. When the pH of the reaction system (?) Is 3 or less, the copper (II) ion and the hydrogen ion in the reaction system (?) Are reduced by the reducing agent to sufficiently produce the copper hydride microparticle (b1). It is also believed that copper (I) chloride is formed from copper (I) ions and chloride ions in which copper (II) ions are reduced, thereby producing hydrogenated copper microparticles (b1) containing chlorine atoms in a water-insoluble form. The pH of the reaction system (?) Is more preferably 0.5 to 2 in view of the production efficiency of the copper hydride fine particle (b1).

The acid for adjusting the pH of the reaction system (?) May be the same as those exemplified in the description of the production of the conductive copper particles (A), and the effect of suppressing the oxidation of the surface of the conductive copper particles (B) , And formic acid is particularly preferable from the viewpoint that the rise of the volume resistivity of the conductor film can be easily suppressed.

The oxidation-reduction potential (ORP) of the reaction system (?) Is preferably 220 ㎷ or less and 150 to 220.. When the ORP is 220 ㎷ or less, the reducing effect of the copper (II) ion becomes large, and the copper hydride copper particle (b1) is sufficiently generated. If the ORP exceeds 220 ㎷, the surface modification becomes insufficient, and not only the initial volume resistivity becomes large, but also the change with time in the volume resistivity becomes large.

Examples of the reducing agent include those exemplified in the description of the production of the conductive copper particles (A), and hypophosphorous acid, hypophosphite, dimethylamine borane or borohydride salts are preferable, and hypophosphorous acid or hypophosphite is particularly preferable desirable.

The amount of the reducing agent to be added is preferably from 1.2 to 10 times the amount of the water-soluble copper compound to be used. When the addition amount of the reducing agent is 1.2 times or more based on the amount of the water-soluble copper compound, the reduction reaction proceeds smoothly. If the addition amount of the reducing agent is 10-fold mol or less relative to the water-soluble copper compound, the amount of the impurities (sodium, boron, phosphorus, etc.) contained in the copper hydride copper fine particles (b2) can be easily suppressed.

The reaction system (?) May be formed by mixing a reducing agent solution prepared by dissolving a reducing agent in a solvent such as water and a solution obtained by dissolving a water-soluble copper compound in a solvent such as water (hereinafter referred to as a "water-soluble copper compound solution"), Of the solid state reducing agent may be added to the water-soluble copper compound solution.

The reaction system (?) Means a system in which copper hydride fine particles are produced. Concretely, immediately after the addition of a reducing agent to a water-soluble copper compound solution containing copper (II) ion and chloride ion and having a pH of 3 or less, A system in which the production reaction of the fine copper hydride microparticles (b1) is proceeding, a system in which the production reaction of the fine copper hydride microparticles (b1) is proceeding, b1) is dispersed. The reaction system (?) Contains a solvent for a water-soluble copper compound solution, a water-soluble copper compound dissolved in the solvent (which is substantially ionized and is present as a copper (II) ion and a pair of anions and the like) (Which is substantially ionized and exists as a chloride ion and a pair of cations and the like), ions and residues after the generation of the copper hydride copper particles (b1), a reducing agent and decomposition products thereof exist.

For example, when the resulting copper hydride microparticles (b1) are isolated and dispersed in a dispersion medium to prepare a dispersion, the copper hydride microparticles (b1) in the dispersion are obtained by reacting the copper hydride microparticles (b1) present in the reaction system no.

The reaction temperature of the reaction system (?) Is preferably 60 占 폚 or lower, more preferably 5 to 60 占 폚, and particularly preferably 20 to 50 占 폚. Copper hydride has a property of being decomposed by heating, but when the reaction temperature of the reaction system (β) is not higher than the upper limit, decomposition of the copper hydride copper fine particles (b2) is easily suppressed. When the reaction temperature of the reaction system (?) Is not lower than the lower limit, the reduction reaction is likely to proceed.

Step (β-2):

Copper particles (b2) as primary particles were added to the reaction system (?) Formed in the step (?-1), and the copper hydride complex particles (b1) having copper hydride fine particles Conductive copper particles (B)). The copper particles (b2) added in the step (?-2) are such that the oxidation film on the surface is reduced in the reaction system (?) And chlorine atoms are contained in the water-insoluble form and the hydrogenation Copper particles (b1) are attached.

The adding time of the copper particles (b2) to the reaction system (β) is before the generation of the copper hydride microparticles (b1), during the production of the copper hydrogenated microparticles (b1) or after the formation of the copper hydrogenated microparticles (b1). The addition of the copper particles (b2) to the reaction system (?) Before the formation of the copper hydride microparticles (b1) means that the copper particles (b2) already exist at the time when the reaction system (?) Is formed. For example, there is a case in which copper particles (b2) are added to a water-soluble copper compound solution and then a reducing agent is added to form a reaction system (?). The addition of the copper particles (b2) to the reaction system (?) After the formation of the copper hydride microparticles (b1) is a state in which no new generation of the copper hydrided microparticles (b1) (b2) is added to the reaction system (?) in a state in which no further growth of the copper (b1) has occurred. For example, there is a case in which the copper particles (b2) are added after the generation reaction of the copper hydride fine particles (b1) does not occur due to the consumption of copper ions or a reducing agent in the reaction system (β).

The addition of the copper particles (b2) to the reaction system (?) Is preferably carried out before the generation of the copper hydride copper particles (b1) or the generation of the copper hydride copper particles (b1) from the viewpoint of easily obtaining the conductive copper particles It is preferable during the course. Before and during the production of copper hydride copper fine particles (b1), copper (II) ions are present in the reaction system (β). The copper (II) ion is reduced in a state in which the copper particle (b2) and the copper hydride copper particle (b1) coexist by adding the copper particle (b2) while the copper (II) ion is present in the reaction system , The copper particles (b2) and the hydrogenated copper microparticles (b1) are bonded more firmly. The presence of copper (II) ions can be determined by a copper ion electrode, spectroscopic spectrum analysis of ultraviolet and visible light, and a method of measuring copper atom concentration by atomic emission spectrum.

The copper particles (b2) to be added to the reaction system (β) include the same copper particles as the copper particles (a1) described in the production of the conductive copper particles (A), and the average particle size Mu m are preferable.

The content of the copper particles (b2) in the reaction system (β) is preferably such that the content of the copper (II) ion in the aqueous copper compound solution before adding the reducing agent (the water soluble copper compound is all ionized) 1 to 100 parts by mass is preferable, and 5 to 100 parts by mass is more preferable.

Process (? -3):

The produced conductive copper particles (B) are separated from the reaction system (?) To obtain particles in powder form. The method for separating the conductive copper particles (B) is not particularly limited, and examples thereof include centrifugation, filtration and the like.

The separated conductive copper particles (B) are preferably washed with a cleaning liquid such as water to remove soluble impurities attached to the conductive copper particles (B). The solvent of the reaction system (?) And the impurities (anion of the water-soluble copper compound, decomposition product of the reducing agent, etc.) dissolved in the solvent may be removed by solvent substitution or the like before separation.

(Method for producing conductive copper particles (C)) [

Examples of the method for producing the conductive copper particles (C) include a method having the following steps (γ-1) and (γ-2).

(II) ion is reduced in a reaction system (hereinafter referred to as a "reaction system (γ)") containing a copper (II) ion and a chloride ion and having a pH of 3 or less and an ORP of 220 Ω or less (Conductive copper particles (C)) having a mean particle size of 10 nm to 1 占 퐉.

(? -2) conductive copper particles (C) from the reaction system (?).

Process (? -1):

The step (? -1) can be carried out in the same manner as in the step (?-1) in the production of the conductive copper particles (B) except for the following preferable conditions.

The average particle diameter of the secondary particles of the conductive copper particles (C) produced by the reaction system (γ) is preferably 10 nm to 1 μm. The average particle diameter of the conductive copper particles (C) can be controlled by controlling the reaction temperature and reaction time, and adding a dispersant.

Process (? -2):

The step (? -2) can be carried out in the same manner as the step (? -3) in the production of the conductive copper particles (B).

(Method for producing conductive copper particles (D)) [

The conductive copper particles (D) can be produced by preparing the conductive copper particles (B) and heating the obtained conductive copper particles (B) to form the copper hydrogenated microparticles (b1) in the conductive copper particles (B) And converting it into copper fine particles to obtain conductive copper particles (D).

In this case, the copper fine particles produced by converting the copper hydride of the copper hydride fine particles (b1) into metallic copper are not peeled off from the surface of the primary particles (b2). In addition, there is substantially no difference between the size of the copper hydride microparticles (b1) and the size of the produced copper fine particles before heating. Therefore, the conductive copper particles (D) having substantially the same structure and substantially the same average particle diameter as the conductive copper particles (B) are obtained.

The heating temperature is preferably 60 to 120 占 폚, more preferably 60 to 100 占 폚, and even more preferably 60 to 90 占 폚. If the heating temperature is the lower limit value or more, the heating time can be shortened and the production cost can be suppressed. When the heating temperature is not more than the upper limit value, it is easy to suppress the increase of the volume resistivity of the conductor film.

The pressure for heating the conductive copper particles (B) is preferably -101 to -50 ㎪ (gauge pressure). When the pressure at the time of heating is -101 ㎪ or more, a large-scale apparatus is not required, and it becomes easy to remove excess solvent and dry it. When the pressure at the time of heating is -50 ㎪ or less, the time can be shortened and the manufacturing cost can be suppressed.

(Method for producing conductive copper particles (E)) [

As a method of producing the conductive copper particles (E), the conductive copper particles (C) are prepared, the obtained conductive copper particles (C) are heated, and the copper hydride in the conductive copper particles (C) Conductive copper particles (E). In this case, there is substantially no difference between the size of the conductive copper particles (C) before heating and the size of the conductive copper particles (E) produced by heating.

The heating conditions of the conductive copper particles (C) can be the same as the heating conditions of the conductive copper particles (B) in the production method of the conductive copper particles (D).

<Composition for forming conductor>

The composition for forming a conductor of the present invention contains the conductive copper particles and the solvent of the present invention as essential components, and contains a resin binder as required.

The conductive copper particles are preferably at least one selected from the group consisting of the conductive copper particles (A) to (E), and at least one selected from the group consisting of the conductive copper particles (A), the conductive copper particles (B) and the conductive copper particles (D) (A), the conductive copper particles (B), and the conductive copper particles (D) are particularly preferable.

Examples of the solvent include a solvent such as cyclohexanone, cyclohexanol, terpineol, ethylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene Glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate and the like.

The content of the solvent in the composition for forming a conductor is preferably 1 to 20% by mass with respect to the conductive copper particles (100% by mass) from the viewpoint of easy adjustment to a viscosity suitable for printing paste and the like.

Examples of the resin binder include known thermosetting resin binders and thermoplastic resin binders used for metal pastes. It is preferable that the thermosetting resin binder is one which sufficiently undergoes a curing reaction at a temperature at the time of curing. Further, it is preferable that the thermoplastic resin binder is small in tackiness and capable of maintaining the shape of the conductor in the use environment.

Examples of the resin binder include a phenol resin, a melamine resin, a urea resin, a diallyl phthalate resin, an unsaturated alkyd resin, an epoxy resin, a urethane resin, a bismaleimide triazine resin, a silicone resin, an acrylic resin and a polyester resin. Among them, a phenol resin and a polyester resin are preferable, and a phenol resin is particularly preferable.

If the amount of the cured product or the solidified product of the resin binder is too large, the contact between the conductive copper particles is interrupted to increase the volume resistivity of the conductive film. Therefore, the content of the resin binder in the composition for forming a conductor needs to be within a range in which the amount of the cured product or the solidified product does not hinder the conductivity of the conductive copper particles.

The content of the resin binder in the composition for forming a conductor can be appropriately selected in consideration of the ratio of the volume of the conductive copper particles to the voids formed between the conductive copper particles and is preferably 5 to 50 parts by mass relative to 100 parts by mass of the conductive copper particles And more preferably 5 to 20 parts by mass. When the content of the resin binder is not lower than the lower limit value described above, the hardness of the conductor film becomes better. If the content of the resin binder is not more than the upper limit value, the volume resistivity of the conductor film can be suppressed to be low.

The composition for forming a conductor of the present invention may contain various additives (leveling agent, coupling agent, viscosity adjuster, antioxidant, etc.) as needed so long as the effects of the present invention are not impaired.

[Manufacturing method]

The composition for forming a conductor of the present invention can be prepared by mixing the conductive copper particles of the present invention with a solvent and a resin binder which is used as needed. When the thermosetting resin binder is mixed in the resin binder, the thermosetting resin binder may be cured and heated to such an extent that the solvent does not volatilize and disappear. If necessary, mixing may be performed by replacing the inside of the mixing vessel with an inert gas. This makes it easy to suppress the oxidation of the conductive copper particles in the mixing.

The composition for forming an electric conductor of the present invention described above contains the conductive copper particles of the present invention which are not oxidized well in air so that a conductive film having a low volume resistivity and a small change in volume resistivity over time is formed .

&Lt; Substrate on which conductive material is formed &

The substrate on which the conductor of the present invention is formed has a substrate and a conductor film formed on the substrate by the composition for forming a conductor of the present invention. In the substrate on which the conductor of the present invention is formed, it is preferable that the conductor film is a line-shaped wiring, and it is preferably a printed wiring board.

Examples of the substrate include a glass substrate, a plastic substrate (a film substrate such as a polyimide film and a polyester film), a substrate made of a fiber reinforced composite material (a glass fiber reinforced resin substrate, etc.), a ceramics substrate, .

The volume resistivity of the conductor film is preferably 1.0 x 10 &lt; ^-4 &gt; When the volume resistivity is 1.0 x 10 &lt; ^-4 &gt; [Omega] cm or less, the substrate having the conductor of the present invention can be preferably used as a conductor for electronic equipment. The volume resistivity of the conductor film is measured by a 4-probe resistance tester.

The rate of change in the volume resistivity after one month with respect to the volume resistivity of the conductive film immediately after the film formation is preferably 5% or less, more preferably 2% or less.

The thickness of the conductor film is preferably from 1 to 100 占 퐉, more preferably from 5 to 50 占 퐉, from the standpoint of ensuring stable conductivity and easily maintaining the wiring shape.

[Manufacturing method]

The substrate on which the conductor of the present invention is formed can be produced by applying a composition for forming a conductor of the present invention on the substrate surface to form a coating layer and removing volatile components such as a solvent from the coating layer to form a conductor film have. When the composition for forming a conductor of the present invention contains a thermosetting resin binder, a conductor film is formed by removing volatile components such as a solvent from the coating layer and then curing the thermosetting resin binder. In this case, the obtained conductive film contains the conductive copper particles and the cured product of the thermosetting resin binder. When the composition for forming a conductor of the present invention contains a thermoplastic resin binder, a conductor film is formed by removing volatile components such as a solvent from the coating layer. In this case, the obtained conductive film contains the conductive copper particles and the solid thermoplastic resin.

Examples of the application method of the composition for forming a conductor include known methods such as a screen printing method, a roll coating method, an air knife coating method, a blade coating method, a bar coating method, a gravure coating method, a die coating method and a slide coating method have.

When the composition for forming a conductor contains a thermosetting resin binder, the curing of the thermosetting resin binder can be carried out by heating. Examples of the heating method include hot air heating and heat radiation. The heating temperature and the heating time can be appropriately determined according to the properties required for the conductive film. When the composition for forming a conductor contains the conductive copper particles (B) or the conductive copper particles (C) as the conductive copper particles, it is preferable that the hydrogenated copper contained in the conductive copper particles is cured simultaneously with the curing of the thermosetting resin binder It is converted to copper.

In the case where the composition for forming a conductor contains a thermoplastic resin binder and conductive copper particles (B) or conductive copper particles (C) are contained as the conductive copper particles, heating when removing volatile components such as a solvent , The copper hydride contained in the conductive copper particles is converted into metallic copper.

The heating temperature is preferably 100 to 300 占 폚. If the heating temperature is 100 占 폚 or higher, the solvent contained in the composition for forming a conductor is sufficiently volatilized. In addition, curing of the thermosetting resin tends to proceed. If the heating temperature is 300 DEG C or less, a plastic film can be used as a base material for forming the conductor film. The curing time may be a time for sufficiently curing the resin binder in accordance with the curing temperature.

The environment for forming the conductor film is not particularly limited and may be in air or nitrogen with little oxygen. Among them, air is preferable from the standpoint of simplifying the manufacturing facility.

The substrate having the conductor of the present invention described above has a conductor film with a low volume resistivity and a small change in the volume resistivity over time.

Example

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited by the following description. Examples 1 to 5 are Examples, and Examples 6 to 10 are Comparative Examples.

[How to measure]

The measurement method of each numerical value in this embodiment is shown below.

(Average particle size)

The average particle diameter of the copper particles before the reduction treatment and the obtained conductive copper particles were measured as follows. In the case of the primary particles, the particle diameters of 100 particles randomly selected from SEM images obtained by SEM (S-4300, manufactured by Hitachi, Ltd.) were measured and averaged. In the case of secondary particles, the particle diameters of 100 particles randomly selected from TEM images obtained by a transmission electron microscope (TEM) were measured and averaged.

(Chloride ion concentration in the reaction system)

The chloride ion concentration of the reaction system was measured with a chlorine ion electrode (HM-20P, manufactured by Toa Dake Inc.).

(PH of the reaction system)

The pH of the reaction system was measured with a pH meter (HM-20P, manufactured by Toa Dake Co., Ltd.).

(Oxidation-reduction potential of the reaction system)

The measurement of the oxidation-reduction potential (ORP) of the reaction system was carried out with an ORP meter (RM-12P, manufactured by Toa Dake Inc.).

(Chlorine atom content of conductive copper particles)

The content of chlorine atoms in the obtained conductive copper particles was determined by fluorescent X-ray analysis (ZSX100e, manufactured by Rigaku Denki Kogyo Co., Ltd.).

(Surface oxygen amount of conductive copper particles)

The surface oxygen content of the obtained conductive copper particles was measured by X-ray photoelectron spectroscopy (ESCA5500, manufactured by ULVAC, Parsa) to determine the surface oxygen concentration [atomic%] and the surface copper concentration [atomic%], Respectively.

(Water solubility test of chlorine atom in conductive copper particles)

When all of the chlorine atoms contained in the conductive copper particles were eluted into the distilled water, the conductive copper particles in an amount such that the concentration of the chloride ion in the distilled water became 100 mass ppm was immersed in distilled water (dissolved oxygen concentration of 1 mass ppm or less) . Subsequently, the distilled water immersed in the conductive copper particles was stirred at 1000 rpm for 5 seconds using a test tube mixer (HM-01, manufactured by Asuzen Co., Ltd.) at 20 ° C, and then the chloride ion concentration eluted in the distilled water was adjusted to a chloride ion Electrode.

(Thickness of conductor film)

The thickness of the conductor film was measured with DEKTAK3 (Veeco metrology Group).

(Surface resistance value of conductor film)

The surface resistivity of the conductor film was measured immediately after film formation with a 4-probe resistance value meter (manufactured by Mitsubishi Heavy Industries, Ltd., model: lorestaIP MCP-T250). Further, the surface resistance value of the conductor film after one month was again measured, and the rate of change (unit:%) with respect to the surface resistance value immediately after the film formation was obtained.

(Volume resistivity of conductor film)

The product of the thickness of the conductor film and the surface resistance of the conductor film, which was measured by the above method, was calculated to obtain the volume resistivity.

[Example 1]

(Production of conductive copper particles A1)

In a glass beaker, 100 g of copper particles (trade name &quot; 1400YP &quot;, trade name &quot; 1400YP &quot;, manufactured by Mitsui Metal Mining Co., Ltd.) having an average primary particle size of 7 mu m were dispersed in 1800 g of distilled water, 30 g of formic acid 35% by mass hydrochloric acid was added thereto to adjust the chloride ion concentration of the reaction system to 10 mass ppm. Subsequently, the beaker was placed in a water bath at 40 占 폚 and 180 g of a 50% by mass aqueous hypophosphoric acid solution was added with stirring to form a reaction system (?), And stirring was continued for 30 minutes. The pH of the reaction system (a) immediately after addition of hypophosphorous acid, the pH of the reaction system (a) after completion of the reaction and the redox potential (ORP) of the reaction system (a) after completion of the reaction are shown in Table 1.

After completion of the stirring, the precipitate was separated by filtration. The precipitate was redispersed in 600 g of distilled water, and then the agglomerates were precipitated by centrifugation again to separate the precipitate. The precipitate was heated at 80 DEG C for 60 minutes under reduced pressure of -35 DEG C (gauge pressure), and the residual moisture was removed by volatilization to obtain conductive copper particles A1.

The content of chlorine atoms in the conductive copper particles A1 was 100 mass ppm. As a result of conducting a water-solubility test of the conductive copper particles A1, the concentration of chloride ions eluted in the distilled water was less than 5 mass ppm. That is, the chlorine atoms contained in the conductive copper particles A1 were in a water-insoluble form. The average particle diameter of the conductive copper particles A1 was 7 mu m.

(Preparation of composition for forming conductor film)

1.2 g of the conductive copper particle A1 was added to a resin solution obtained by dissolving 0.26 g of a phenol resin (trade name: "REGOTOP PL6220", manufactured by Mfg. Co., Ltd.) in 0.15 g of ethylene glycol monobutyl ether acetate. This mixture was placed in a mortar and mixed at room temperature to obtain a composition for forming a conductive film. The amount of the phenol resin added was 11 parts by mass based on 100 parts by mass of the conductive copper particles A1.

(Formation of conductor film)

The obtained composition for forming a conductive film was coated on a glass substrate and heated at 150 占 폚 for 1 hour to cure the phenolic resin to form a conductive film having a thickness of 20 占 퐉 and the volume resistivity of the conductive film was measured.

[Example 2]

(Production of conductive copper particle A2)

Conductive copper particle A2 was obtained in the same manner as in Example 1 except that the chloride ion concentration in the reaction system (?) Was 25 mass ppm.

The content of the chlorine atom of the obtained conductive copper particle A2 was 250 mass ppm. Further, as a result of conducting the water-solubility test of the conductive copper particle A2, the concentration of the chloride ion eluted into the distilled water was less than 5 mass ppm. That is, the chlorine atom contained in the conductive copper particle A2 was in a water-insoluble form. The average particle diameter of the conductive copper particles A2 was 7 mu m.

(Preparation of composition for forming conductor film)

Using the conductive copper particles A2, a composition for forming a conductive film was obtained in the same manner as in Example 1.

(Formation of conductor film)

Using the thus obtained composition for forming a conductive film, a conductive film was formed in the same manner as in Example 1, and the volume resistivity thereof was measured.

[Example 3]

(Production of conductive copper particles D1)

In a glass beaker, 100 g of copper particles (trade name &quot; 1400YP &quot;, manufactured by Mitsui Mining &amp; Metallurgy Co., Ltd., average primary particle size 7 μm) were dispersed in 1800 g of distilled water. Next, 15 g of formic acid as a pH regulator, 39 g of copper formate as a water-soluble copper compound, and 35 mass% hydrochloric acid as a compound for generating chloride ion were added to adjust the chloride ion concentration of the reaction system to 10 mass ppm. Subsequently, the beaker was placed in a water bath at 40 占 폚 and 180 g of a 50% by mass aqueous hypophosphoric acid solution was added with stirring to form a reaction system (?), And stirring was continued for 30 minutes. After completion of the stirring, the reaction system (?) Was treated in the same manner as the reaction system (?) Of Example 1 to obtain conductive copper particles D1. In this example, once the conductive copper particles B1 in the form of secondary particles of copper hydride adhered to the surface of the copper particles as the primary particles are generated and heated at 80 DEG C for 60 minutes in order to volatilize the residual water , It is considered that copper hydride copper particles are converted into copper fine particles to obtain conductive copper particles D1.

The content of chlorine atoms in the obtained conductive copper particles D1 was 150 mass ppm. Furthermore, as a result of conducting the water-solubility test of the conductive copper particles D1, the concentration of chloride ions eluted into the distilled water was less than 5 mass ppm. That is, the chlorine atoms contained in the conductive copper particles D1 were in a water-insoluble form. The average particle diameter of the conductive copper particles D1 was 8 占 퐉.

(Preparation of composition for forming conductor film)

1.2 g of the conductive copper particle D1 was added to a resin solution obtained by dissolving 0.15 g of an amorphous polyester resin (manufactured by Toyo Roshi KK, trade name "VIRON 300") in 0.35 g of cyclohexanone. This mixture was placed in a mortar and mixed at room temperature to obtain a composition for forming a conductive film. The amount of the amorphous polyester resin added was 11 parts by mass with respect to 100 parts by mass of the conductive copper particles D1.

(Formation of conductor film)

The obtained composition for forming a conductor film was applied to a glass substrate and heated at 150 占 폚 for 1 hour to cure the amorphous polyester resin to form a conductor film having a thickness of 20 占 퐉 and the volume resistivity of the conductor film was measured.

[Example 4]

(Production of conductive copper particles D2)

Conductive copper particles D2 were obtained in the same manner as in Example 3 except that the chloride ion concentration in the reaction system (?) Was changed to 15 mass ppm.

The content of chlorine atoms in the obtained conductive copper particles D2 was 400 mass ppm. Further, as a result of conducting the water-solubility test of the conductive copper particles D2, the concentration of the chloride ion eluted into the distilled water was 8 mass ppm. That is, the chlorine atoms contained in the conductive copper particles D2 were in a water-insoluble form. The average particle diameter of the conductive copper particles D2 was 8 占 퐉.

(Preparation of composition for forming conductor film)

Using the conductive copper particles D2, a composition for forming a conductive film was obtained in the same manner as in Example 3.

(Formation of conductor film)

Using the thus obtained composition for forming a conductive film, a conductive film was formed in the same manner as in Example 1, and the volume resistivity thereof was measured.

[Example 5]

(Production of conductive copper particles D3)

Conductive copper particles D3 were obtained in the same manner as in Example 3 except that the chloride ion concentration in the reaction system (?) Was 25 mass ppm.

The content of chlorine atoms in the obtained conductive copper particles D3 was 700 mass ppm. As a result of conducting a water-solubility test of the conductive copper particles D3, the concentration of the chloride ion eluted into the distilled water was 10 mass ppm. That is, the chlorine contained in the conductive copper particles D3 was in a water-insoluble form. The average particle diameter of the conductive copper particles D3 was 8 占 퐉.

(Preparation of composition for forming conductor film)

Using the conductive copper particles D3, a composition for forming a conductive film was obtained in the same manner as in Example 3.

(Formation of conductor film)

Using the thus obtained composition for forming a conductive film, a conductive film was formed in the same manner as in Example 1, and the volume resistivity thereof was measured.

[Example 6]

(Preparation of conductive copper particles)

In a glass beaker, 100 g of copper particles (trade name &quot; 1400YP &quot;, trade name &quot; 1400YP &quot;, manufactured by Mitsui Metal Mining Co., Ltd.) having an average primary particle diameter of 7 mu m were dispersed in 1800 g of distilled water, and 30 g of formic acid was added. The conductive copper particles F1 were obtained in the same manner as in Example 1, except that 90 g of sulfuric acid was added while stirring to form a reaction system.

The content of chlorine atoms in the obtained conductive copper particles F1 was less than 50 mass ppm.

(Preparation of composition for forming conductor film)

Using the conductive copper particles F1, a composition for forming a conductor film was obtained in the same manner as in Example 1.

(Formation of conductor film)

Using the thus obtained composition for forming a conductive film, a conductive film was formed in the same manner as in Example 1, and the volume resistivity thereof was measured.

[Example 7]

(Preparation of conductive copper particles)

In a glass beaker, 100 g of copper particles (trade name &quot; 1400YP &quot;, trade name &quot; 1400YP &quot;, manufactured by Mitsui Mining &amp; Metals Mfg. Co., Ltd., average primary particle size: 7 mu m) were dispersed in 1,800 g of distilled water. The beaker was placed in a water bath at 40 DEG C, And 72 g were added to form a reaction system, conductive copper particles F2 were obtained in the same manner as in Example 1.

The content of the chlorine atom of the obtained conductive copper particles F2 was less than 50 mass ppm.

(Preparation of composition for forming conductor film)

Using the conductive copper particles F2, a composition for forming a conductor film was obtained in the same manner as in Example 1.

(Formation of conductor film)

Using the thus obtained composition for forming a conductive film, a conductive film was formed in the same manner as in Example 1, and the volume resistivity thereof was measured.

[Example 8]

(Preparation of conductive copper particles)

In a glass beaker, 100 g of copper particles (trade name &quot; 1400YP &quot;, trade name &quot; 1400YP &quot;, average primary particle diameter 7 m) manufactured by Mitsui Mining & Metals Mining Co., Ltd.) was dispersed in 1800 g of distilled water, and 35% by mass hydrochloric acid was added to adjust the concentration of chlorine atoms in the reaction system to 100 The conductive copper particles F3 were obtained in the same manner as in Example 1 except that the beaker was placed in a water bath at 40 占 폚 and then 72 g of formic acid was added with stirring to form a reaction system.

The obtained conductive copper particles F3 had a chlorine content of 300 mass ppm. Further, as a result of conducting the water-solubility test of the conductive copper particles F3, the concentration of the chloride ion eluted into the distilled water was 30 mass ppm. That is, the chlorine contained in the conductive copper particles F3 was water-soluble.

(Preparation of composition for forming conductor film)

Using the conductive copper particles F3, a composition for forming a conductor film was obtained in the same manner as in Example 1.

(Formation of conductor film)

Using the thus obtained composition for forming a conductive film, a conductive film was formed in the same manner as in Example 1, and the volume resistivity thereof was measured.

[Example 9]

(Preparation of conductive copper particles)

Conductive copper particles were obtained in the same manner as in Example 7, and hydrochloric acid was further added to the conductive copper particles so that the content of chlorine atoms was 100 mass ppm to obtain conductive copper particles F4.

The content of chlorine atoms in the obtained conductive copper particles F4 was 100 mass ppm. Further, as a result of conducting the water-solubility test of the conductive copper particles F4, the concentration of chloride ions eluted into the distilled water was 90 mass ppm. That is, the chlorine contained in the conductive copper particles F4 was water-soluble.

(Preparation of composition for forming conductor film)

Using the conductive copper particles F4, a composition for forming a conductor film was obtained in the same manner as in Example 1.

(Formation of conductor film)

Using the thus obtained composition for forming a conductive film, a conductive film was formed in the same manner as in Example 1, and the volume resistivity thereof was measured.

[Example 10]

(Preparation of conductive copper particles)

After obtaining conductive copper particles in the same manner as in Example 7, hydrochloric acid was further added to the conductive copper particles so that the content of chlorine atoms was 1,000 ppm by mass to obtain conductive copper particles F5.

The content of chlorine atoms in the obtained conductive copper particles F5 was 1,000 ppm by mass. Further, as a result of conducting the water-solubility test of the conductive copper particles F5, the concentration of the chloride ion eluted into the distilled water was 90 mass ppm. That is, the chlorine contained in the conductive copper particles F5 was water-soluble.

(Preparation of composition for forming conductor film)

Using the conductive copper particles F5, a composition for forming a conductive film was obtained in the same manner as in Example 1.

(Formation of conductor film)

Using the thus obtained composition for forming a conductive film, a conductive film was formed in the same manner as in Example 1, and the volume resistivity thereof was measured.

Table 1 shows properties and evaluation results of the reaction system, conductive copper particles and conductive film in Examples 1 to 10.

As shown in Table 1, the conductive films of Examples 6 and 7 using conductive copper particles having a chlorine atom content of less than 50 mass ppm and conductive films of Examples 8 to 10 using conductive copper particles containing a chlorine atom in water- Even if the volume resistivity was high immediately after the film formation or the volume resistivity immediately after the film formation was low, the volume resistivity was increased by preservation. On the other hand, the conductor films of Examples 1 to 5 using the conductive copper particles of the present invention containing 50 to 1000 mass ppm of chlorine atoms in a non-aqueous form had a low volume resistivity and a low rate of change after one month.

While the invention has been described in detail and with reference to specific embodiments thereof, it is evident to those skilled in the art that various modifications and variations can be made without departing from the scope and spirit of the invention.

This application is based on Japanese Patent Application No. 2010-226632 filed on October 6, 2010, the content of which is incorporated herein by reference.

Industrial availability

The conductive copper particles and composition for forming a conductive film of the present invention can be suitably used for various applications such as formation and repair of wiring patterns in printed wiring boards and the like, interlayer wiring in semiconductor packages, bonding of printed wiring boards and electronic components.

Claims (6)

A process for producing conductive copper particles containing chlorine atoms in an amount of 50 to 1000 mass ppm relative to the total mass of the particles and in which the chlorine atoms are present in a water-
Wherein at least one of copper particles and copper (II) ions is reduced in a reaction system containing chloride ions and having a pH of 3 or less and an oxidation-reduction potential of 220 ㎷ or less. The method according to claim 1,
Wherein the average particle diameter is 0.01 to 20 占 퐉. delete delete delete delete