KR101976855B1 - Conductive paste and substrate with conductive film - Google Patents

Abstract

It is possible to provide a conductive paste capable of forming a conductive film having a high conductivity and exhibiting good adhesiveness only by directly coating and curing without forming a ground layer on the ITO film and without activating the surface of the ITO film, . (A) copper particles having an average particle diameter of 10 nm to 20 탆, (B) an amine salt of an organic polymer having a phosphoric acid group, and (C) a thermosetting resin containing formaldehyde as one component , 5 to 40 parts by mass of the binder resin of the component (C) relative to 100 parts by mass of the copper particles of the component (A), and 100 parts by mass of the component (B) And 0.1 to 100 parts by mass of a salt of an organic polymer.

Description

TECHNICAL FIELD [0001] The present invention relates to a conductive paste,

The present invention relates to a conductive paste and a base material with a conductive film using the conductive paste.

BACKGROUND ART Conventionally, a method of using a conductive paste containing metal particles with high conductivity for forming wiring conductors such as electronic parts and printed wiring boards has been known. Among them, the production of the printed wiring board is carried out by coating a conductive paste on an insulating substrate in a desired pattern and curing the conductive paste to form a conductive film constituting a wiring pattern.

As a conductive paste, a silver paste containing silver particles as metal particles has been the mainstream in the past (Patent Document 1), but there is a problem in terms of migration. In this respect, the copper paste containing copper particles as metal particles does not easily migrate, so that the connection reliability of the electric circuit can be enhanced.

Various characteristics are required for a wiring conductor such as a printed wiring board. However, the adhesion of the wiring pattern to the insulating substrate is one of the most important characteristics because it affects the connection reliability of the electric circuit.

(PET), polyimide (PI), and the like have been conventionally used as a substrate used for a printed wiring board. In recent years, in view of the use of touch panels and the like, , A tin-doped indium oxide (ITO) film, and the like are used. When such a substrate with a transparent conductive film is used as a printed wiring board, a conductive paste is applied on the transparent conductive film to form a conductive film (see, for example, Patent Document 2).

An ITO film is widely used as the transparent conductive film in the substrate with a transparent conductive film used for the above purpose.

In such a case, as a method for improving the adhesion of the conductive film to the ITO film, a method in which a solution obtained by dissolving the transition metal compound in an organic solvent is applied to the surface of the ITO film and heat treatment is performed to form a base layer (See, for example, Patent Document 3).

However, this method requires the formation of a ground layer, and since the step of applying the conductive paste after forming the ground layer is performed, there is a problem that the number of steps increases and workability is poor.

In order to improve the adhesion of a conductive paste applied on a transparent conductive film such as an ITO film, a method of activating the surface of the transparent conductive film by treating with an acidic or alkaline solution, a method of irradiating ultraviolet rays or electron rays, A method of making the surface of the transparent conductive film active by performing a corona treatment or a plasma treatment is known (see, for example, Patent Document 4).

However, in this method, since the step of applying the conductive paste is performed after the above-described processing, there is a problem that the number of steps increases and workability is poor.

Japanese Patent Application Laid-Open No. 5-212579 JP-A-2009-116452 Japanese Patent Application Laid-Open No. 2005-293937 Reissue Patent Publication No. 99/59814 (WO99 / 59814)

In order to solve the problems of the prior art described above, it is an object of the present invention to provide an ITO film which does not have a base layer on the ITO film and which does not activate the surface of the ITO film, To provide a conductive paste capable of forming a conductive film having high conductivity and a substrate having a conductive film formed using such a conductive paste.

(B) an amine salt of an organic polymer having a phosphoric acid group; (C) an aqueous solution of formaldehyde as a single component; (C) is contained in an amount of 5 to 40 parts by mass based on 100 parts by mass of the copper particles of the component (A), and the binder resin 100 of the component (C) And 0.1 to 100 parts by mass of an amine salt of the organic polymer of the component (B) relative to the mass part.

In the conductive paste of the present invention, the organic polymer salt of the component (B) preferably has an acid value of 10 to 200 mgKOH / g and an amine value of 10 to 200 mgKOH / g.

In the conductive paste of the present invention, the amine salt of the organic polymer as the component (B) is preferably an ammonium salt, an alkylamine salt, or an alkylolamine salt of an organic polymer having a phosphoric acid group.

In the conductive paste of the present invention, the binder resin of the component (C) is preferably at least one selected from the group consisting of a phenol resin, a melamine resin, a xylene resin, and a urea resin.

The conductive paste of the present invention preferably further contains a carboxylate of a polymer compound having at least one primary amino group in the molecule (D).

In the conductive paste of the present invention, the component (D) is preferably a formate of polyethyleneimine or a salt of polyallylamine.

In the conductive paste of the present invention, it is preferable that the conductive paste contains 0.05 to 5 parts by mass of the carboxylate of the polymer compound of the component (D) based on 100 parts by mass of the copper particles of the component (A).

In the conductive paste of the present invention, it is preferable that the particle diameter when the integrated value from the side of the small particle diameter is 10% is D10, and the particle diameter when the particle diameter is 50% When the particle diameter at D50 and 90% is D90, it is preferable that the value of D90 / D50 is 4.0 or less and the value of D90 / D10 is 3.0 or more.

In the conductive paste of the present invention, the copper particles of component (A) are preferably copper particles having a surface oxygen content of 0.5 or less.

Further, the present invention provides a conductive film-attached substrate characterized by having a conductive film formed by applying the conductive paste of the present invention and curing on the ITO film of a substrate having a tin-doped indium oxide (ITO) film.

According to the present invention, it is possible to form a conductive film having good adhesion with the ITO film and having high conductivity without forming a ground layer on the ITO film of the substrate having the ITO film and without activating the surface of the ITO film The conductive paste having the above properties can be obtained.

Further, according to the present invention, by using such a conductive paste, it is possible to obtain a substrate with a conductive film having a conductive film with good adhesion to the ITO film and high conductivity.

Hereinafter, an embodiment of the present invention will be described. The present invention is not limited to the following description.

≪ Conductive paste &

The conductive paste of the present invention comprises (A) copper particles having an average particle diameter of 10 nm to 20 μm, (B) an amine salt of an organic polymer having a phosphoric acid group, and (C) a thermosetting resin containing (C) is contained in an amount of 5 to 40 parts by mass based on 100 parts by mass of the copper particles of the component (A), and 100 parts by mass of the binder resin of the component (C) And 0.1 to 100 parts by mass of a salt of an organic polymer of the component (B). Hereinafter, each component constituting the conductive paste will be described in detail.

(A) Copper particles

The copper particles of the component (A) are conductive components of the conductive paste.

The average particle diameter of the copper particles of the component (A) is in the range of 10 nm to 20 탆. Depending on the shape of the copper particles, it may be appropriately adjusted within this range. As described later, one or more of copper particles, copper hydride copper particles, copper composite particles, and copper fine particles may be used as the copper particles. If the average particle diameter of the copper particles is not less than the lower limit value, the flow characteristics of the conductive paste including the copper particles become good. When the average particle diameter of the copper particles is not more than the upper limit value, the fine wiring can be easily produced.

As the copper particles of component (A), for example, copper particles (A1) to (A5) shown below are preferably used.

(A1) Copper particles having an average primary particle size of 0.3 to 20 탆.

(A2) Copper composite particles having fine copper hydride microparticles having an average aggregate particle diameter of 20 to 400 nm adhered to the surface of copper particles having an average primary particle diameter of 0.3 to 20 탆.

(A3) Copper hydride microparticles having an average aggregate particle diameter of 10 nm to 1 탆.

(A4) Copper composite particles having copper fine particles having an average aggregate particle diameter of 20 to 400 nm adhered to the surface of copper particles having an average primary particle diameter of 1 to 20 占 퐉.

(A5) Copper fine particles having an average aggregate particle diameter of 10 nm to 1 占 퐉.

The copper hydrogenated microparticles are converted into metallic copper by heating to become copper microparticles. That is, the copper composite particle A2 to which copper hydride fine particles are adhered becomes a copper composite particle A4 to which copper fine particles are adhered when heated. Further, the copper hydride copper fine particles (A3) are heated to become copper fine particles (A5).

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

In the case of the copper particles and the particles containing the copper hydride fine particles adhering to the copper particles as in the above copper particles (A2), the entirety of the particles is observed by SEM, and after the addition of the copper hydride fine particles Feret diameter is measured.

When the particle diameter of the component (A) based on the number of copper particles is D10, the particle diameter when the integrated value from the particle diameter side is 10% is D10, and the particle diameter when D50 is 90% D90, it is preferable that the value of D90 / D50 is 4.0 or less and the value of D90 / D10 is 3.0 or more. When the value of D90 / D50 is 4.0 or less, it is easy to produce a fine wiring using a conductive paste. When the value of D90 / D10 is 3.0 or more, the density of copper particles in the conductive film formed by using the conductive film paste is improved and the conductivity is improved.

The particle diameter distribution based on the number of copper particles of the component (A) is obtained from the measurement result of the Feret diameter obtained by the above procedure. Specifically, the integrated value from the small particle diameter side was determined, and the particle diameter when the integrated value from the small particle diameter side was 10% was D10, the particle size when the integrated value from the small particle diameter side was 50% was D50, And the particle diameter when the integrated value from the particle diameter side is 90% is D90.

The copper particles of component (A) preferably have a surface oxygen content of 0.5 or less. When copper particles having a surface oxygen amount of 0.5 or less are used, the contact resistance between the copper particles becomes smaller, and the conductivity of the resulting conductive film is improved.

The "surface oxygen amount" in the present invention is represented by the ratio of the surface oxygen concentration (unit: atom%) to the surface copper concentration (unit: atom%) of the copper particles. Further, the surface copper concentration and the surface oxygen concentration of the copper particles are obtained by X-ray photoelectron spectroscopy. The measurement is made in the range from the particle surface to the center to a depth of about 3 nm. If the measurement is performed in this range, the state of the particle surface can be grasped sufficiently.

As the copper particles having a surface oxygen amount of 0.5 or less, "surface-modified copper particles" obtained by reducing the surface of copper particles or "composite metal copper particles" having copper particles attached to at least part of the surface of copper particles can be preferably used .

The "surface-modified copper particles" in the present invention are obtained by reducing the surfaces of copper particles in a dispersion medium having a pH value of 3 or less. For example, (1) Copper particles are dispersed in a dispersion medium to form a "copper dispersion" (2) adjusting the pH value of the copper dispersion to a predetermined value or less, and (3) adding a reducing agent to the copper dispersion.

The " composite metal copper particles " in the present invention are obtained by heating "copper composite particles" in which metal copper fine particles are adhered to at least a part of the surfaces of metal copper particles and copper hydride fine particles are adhered to the surfaces of the metal copper particles , And copper hydrogenated microparticles into metal copper microparticles. The presence or absence of the fine particles on the surface of the metal copper particles can be confirmed by observing the SEM image. The copper hydride fine particles attached to the surface of the metal copper particles can be identified by using an X-ray diffraction apparatus (TTR-III, manufactured by Rigaku Corporation).

As the copper copper particles in the copper composite particles, known copper particles commonly used in conductive pastes may be used, and the particle shape thereof may be spherical or plate-like. The average particle diameter (average primary particle diameter) of the metallic copper particles is preferably 0.3 to 20 탆, more preferably 1 to 10 탆. When the average particle diameter of the metal copper particles is less than 0.3 탆, sufficient flow characteristics can not be obtained when the conductive paste is used. On the other hand, when the average particle diameter of the metal copper particles exceeds 20 탆, there is a fear that the production of the fine wiring by the obtained conductive paste becomes difficult. The average particle diameter (average primary particle diameter) of the metallic copper particles was calculated by measuring the Feret diameter of 100 metallic copper particles randomly extracted from the TEM image or the SEM image as described above and averaging these measured values .

Copper hydride copper particles in the copper composite particles exist mainly as secondary particles in which primary particles of about 1 to 20 nm are aggregated, and the particle shape thereof may be spherical or plate. The average particle size (average agglomerated particle diameter) of the copper hydride fine particles is preferably 20 to 400 nm, more preferably 30 to 300 nm, still more preferably 50 to 200 nm. And particularly preferably 80 to 150 nm. If the mean particle size (average aggregate particle diameter) of the copper hydride fine particles is less than 20 nm, the adhesion and growth of the copper hydride fine particles are liable to occur, and there is a possibility that problems such as cracks accompanying volume contraction may occur . On the other hand, when the average particle size (average aggregate particle diameter) of the copper hydride fine particles exceeds 400 nm, the surface area of the particles is insufficient and the surface fusion phenomenon does not occur easily, making it difficult to form a dense conductive film. The average particle size (average aggregate particle size) of the hydrogenated copper microparticles was calculated by measuring the particle diameters of 100 hydrogenated copper microparticles randomly extracted from the TEM image or the SEM image as described above and averaging the measured values.

The amount of the hydrogenated copper fine particles attached to the surface of the metal copper particles is preferably 5 to 50 mass%, more preferably 10 to 35 mass%, of the amount of the metal copper particles. If the amount of the copper hydride fine particles is less than 5% by mass of the amount of the metallic copper particles, a conductive path is not sufficiently formed between the metallic copper particles, and the effect of reducing the volume resistivity of the conductive film may not be sufficiently obtained. On the other hand, when the amount of the copper hydride fine particles exceeds 50 mass% of the amount of the copper copper particles, it becomes difficult to secure sufficient fluidity as the conductive paste. The amount of the copper hydride fine particles adhering to the surface of the metal copper particles can be adjusted by changing the copper ion concentration in the solution of the water-soluble copper compound before the addition of the reducing agent and the concentration of the copper ion remaining in the reaction solution after completion of the generation of the copper- Can be calculated from the car.

(B) an amine salt of an organic polymer having a phosphoric acid group

In the conductive paste using the silver particles as the conductive particles, a thermoplastic resin such as a polyester resin or a phenoxy resin is used as the binder resin because it can be cured at a low temperature and for a short time.

On the other hand, in the case of the conductive paste of the present invention, since the copper particles of the component (A) are easily oxidized as compared with the silver particles, the binder resin (C) A thermosetting resin is used.

However, when a thermosetting resin is used as the binder resin, when the conductive paste is applied on the ITO film to form the conductive film, the adhesion of the conductive film to ITO is inferior. This is because the polarity of the resin is large and the surface energy is large, so that the wettability to the ITO film surface is deteriorated, and it is difficult to secure a sufficient adhesion area.

Therefore, in the case of forming a conductive film on an ITO film by using a conductive paste using copper particles as conductive particles, a method of forming a ground layer on the ITO film (see Patent Document 3) and a process of activating the surface of the ITO film It is necessary to improve the adhesion of the conductive film to the ITO film.

On the contrary, in the conductive paste of the present invention, the conductive film formed using the conductive paste exhibits good adhesion to the ITO film by blending the amine salt of the organic polymer having the phosphoric acid group as the component (B). There are two reasons for this.

1. Of the components (B), the phosphate group and the portion constituting the amine salt exhibit an interaction with the ITO film.

2. Of the components (B), the organic polymer portion exhibits compatibility with the binder resin of the component (C).

As a result, in the conductive paste, the organic polymer portion of the component (B) was compatible with the binder resin of the component (C), and the phosphate group and the portion constituting the amine salt of the component (B) exhibited interaction with the ITO film Therefore, the conductive film formed using the conductive paste exhibits good adhesion to the ITO film.

By mixing the component (B) having a surface-active function, the interfacial energy between the surface of the ITO film and the conductive paste is reduced to improve the wettability of the conductive paste on the ITO film surface, The conductive film formed using the ITO film exhibits good adhesion to the ITO film.

The amine salt of the organic polymer having a phosphoric acid group constituting the component (B) has at least one phosphoric acid group and a moiety constituting the amine salt. As described above, since the portions constituting the phosphoric acid group and the amine salt in component (B) exert their interaction with the ITO film, the organic polymer salt preferably has a plurality of phosphoric acid groups, Is satisfied.

Specifically, the acid value (in accordance with JIS K 7237) is preferably from 10 to 200 mgKOH / g, and more preferably from 30 to 100 mgKOH / g. If the acid value is less than 10 mgKOH / g, the adhesion with the ITO film may be deteriorated. When the acid value is more than 200 mgKOH / g, the organic polymer moiety has a low molecular weight having a carbon number of 9 or less, and there is a fear that the compatibility with the binder resin of the component (C) is lowered.

The amine value (in accordance with the provisions of JIS K 7237) is preferably 10 to 200 mgKOH / g, more preferably 30 to 100 mgKOH / g. If the amine value is less than 10 mgKOH / g, adhesion with the ITO film may be deteriorated. When the amine value is more than 200 mgKOH / g, the organic polymer moiety has a low molecular weight having a carbon number of 9 or less, which may lower the compatibility with the binder resin of the component (C).

Examples of suitable amine salts of the organic polymer constituting the component (B) include ammonium salts, alkylamine salts, and alkylolamine salts of organic polymers having a phosphoric acid group.

The organic polymer portion is preferably an organic polymer having a carbon number of 10 or more, more preferably an organic polymer having a carbon number of 100 or more. May have a linear main chain, or may have a branched structure. When the organic polymer moiety is a copolymer, it may be a block copolymer, an alternate copolymer, a graft copolymer, or a random copolymer. The organic polymer portion is preferably a polyester and / or polyoxyethylene.

As the amine salt of the organic polymer constituting the component (B), a commercially available product may be used. Specific examples of commercially available products include Disperbyk 180 (manufactured by Big Chemical) and Disperbyk 144 (manufactured by Big Chemical).

In the conductive paste of the present invention, the amount of the amine salt of the organic polymer as the component (B) is from 0.1 to 100 parts by mass based on 100 parts by mass of the binder resin of the component (C). That is, the compounding ratio of the component (B) (amine salt of the organic polymer) to the component (C) (binder resin) is 0.1 to 100 mass%. When the compounding amount of the amine salt of the organic polymer as the component (B) is 0.1 part by mass or more based on 100 parts by mass of the binder resin of the component (C), the adhesion of the conductive film formed with the conductive paste to the ITO film surface is improved. When the amount of the amine salt of the organic polymer as the component (B) is 100 parts by mass or less based on 100 parts by mass of the binder resin of the component (C), the volume resistivity of the conductive film is lowered, A conductive film can be formed.

The amount of the amine salt of the organic polymer as the component (B) is 0.5 to 40 parts by mass relative to 100 parts by mass of the binder resin of the component (C), that is, the amount of the component (C) (Binder resin) is preferably 0.5 to 40% by mass.

(C) Binder resin

As described above, in the conductive paste using copper particles as the conductive particles, a thermosetting resin is used as the binder resin. In the conductive paste of the present invention, as the binder resin of the component (C), a thermosetting resin containing formaldehyde as one component is used. This is because the oxidation of the surface of the copper particles can be suppressed by the reducing action of the methylol groups generated from formaldehyde, and the curing shrinkage progresses appropriately to secure the contact between the copper particles.

Examples of the thermosetting resin having one component of formaldehyde include phenol resin, melamine resin, xylene resin and urea resin. Among them, the phenol resin is preferable in terms of the reducing action of the methylol group and the degree of curing shrinkage. If the hardening shrinkage is too large, an unnecessary stress accumulates in the conductive film, which causes mechanical breakdown. If the hardening shrinkage is too small, the contact between the copper particles can not be sufficiently secured.

In the conductive paste of the present invention, the amount of the binder resin of the component (C) may be properly selected depending on the volume of the copper particles of the component (A) and the volume of the void portion existing between the copper particles. Is preferably 5 to 40 parts by mass, more preferably 5 to 20 parts by mass, per 100 parts by mass of the copper particles. When the amount is 5 parts by mass or more, the flowability of the conductive paste is improved. When the amount is 40 parts by mass or less, the volume resistivity of the conductive film formed using the conductive paste can be suppressed to be low.

In the conductive paste of the present invention, the conductive paste of the present invention may further comprise, in addition to the components (A) to (C), a polymer compound containing at least one primary amino group in the molecule , And an amino group-containing polymer compound). By containing the carboxylic acid salt of the amino group-containing polymer compound as the component (D), the adhesion of the conductive film formed by using the conductive paste to the ITO film surface is further improved. The reason is that the amino group such as the primary amino group contained in the amino group-containing polymer compound interacts with the ITO film surface at the same time while forming a bond by the acid base reaction with the acid group of the binder resin as the component (C) .

The amino group-containing polymer compound constituting the component (D) is a high molecular weight amine having at least one, preferably a plurality of primary amino groups in the molecule, and a mass average molecular weight (Mw) of 300 to 20,000. The mass average molecular weight (Mw) of the amino group-containing polymer compound is more preferably in the range of 600 to 1600.

The amino group-containing polymer compound constituting the component (D) preferably contains a secondary amino group and / or a tertiary amino group together with at least one primary amino group, preferably a plurality of primary amino groups. Is in the range of 700 to 1500 mgKOH / g, and particularly preferably 850 to 1200 mgKOH / g. The amino group-containing polymer compound constituting the component (D) may be a compound having a linear main chain or a compound having a branched structure. Among them, a polymer amine having a branched structure is preferable. Specific examples of the amino group-containing polymer compound constituting the component (D) include polyethyleneimine and polyallylamine having a mass average molecular weight (Mw) in the above range. In particular, polyethyleneimine is preferred.

The amino group-containing polymeric compound is a form in which an amino group (primary amino group, secondary amino group and / or tertiary amino group) is reacted with a carboxylic acid to form a salt, and is contained in the conductive paste of the present invention. Examples of the acid which forms a salt with the amino group of the amino group-containing polymer compound include hydrochloric acid, sulfuric acid, nitric acid, carboxylic acid, sulfonic acid and the like, but a carboxylic acid is preferable from the viewpoint of strength of bonding property with an amino group. Among the carboxylic acids, carboxylic acids having 10 or less carbon atoms including carbon atoms of carbonyl groups are preferable, and carboxylic acids having 4 or less carbon atoms are particularly preferable. Specifically, formic acid is particularly preferable.

Therefore, as the carboxylic acid salt of the amino group-containing polymer compound, a formate salt of polyethyleneimine or a formate salt of polyallylamine is preferable, and a formate salt of polyethyleneimine is particularly preferable.

When the carboxylic acid salt of the amino group-containing polymer compound is compounded as the component (D), the amount thereof is preferably 0.05 to 5 parts by mass, more preferably 0.1 to 2 parts by mass, per 100 parts by mass of the copper particles of the component (A) Do. That is, the compounding ratio of the component (D) (amino group-containing polymer compound carboxylate) to the component (A) (copper particle) is preferably 0.05 to 5 mass%, particularly preferably 0.1 to 2 mass% . If the amount of the amino group-containing polymer compound carboxylate as the component (D) is 0.05 parts by mass or more based on 100 parts by mass of the copper particles of the component (A), the adhesion of the conductive film formed using the conductive paste to the ITO film surface . When the amount is less than 5 parts by mass, the conductivity is deteriorated and the volume resistivity of the conductive film is less likely to deteriorate, so that a conductive film having good conductivity can be formed.

(E) Other components

The conductive paste of the present invention may contain, in addition to the above components (A) to (D), a solvent and various additives (leveling agent, coupling agent, viscosity adjusting agent, antioxidant, etc.) It may be contained in a range not inhibiting. In particular, in order to obtain a paste having an appropriate fluidity, it is preferable to include a solvent capable of dissolving the thermosetting resin.

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, di Ethylene glycol, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate. As the printing paste, the amount of the solvent to be contained in the conductive paste is preferably 1 to 10% by mass with respect to the copper particles from the viewpoint of setting the viscosity within a suitable range.

The conductive paste can be obtained by mixing the above components (A) to (D) and, if necessary, other components such as the above-mentioned solvent. The above components (A) to (D) may be mixed while heating at a temperature that does not cause curing of the thermosetting resin or volatilization of the solvent.

The temperature for mixing and stirring is preferably 10 to 40 占 폚. More preferably, the temperature is 20 to 30 占 폚. When the conductive paste is prepared, the viscosity of the paste can be sufficiently lowered by heating at a temperature of 10 占 폚 or higher, and agitation can be performed smoothly and sufficiently. On the other hand, if the temperature at the time of preparing the conductive paste exceeds 40 캜, the resin may be hardened in the paste, or fusion of the particles may occur. Further, in order to prevent the copper particles from being oxidized at the time of mixing, it is preferable to mix them in a container substituted with an inert gas.

In the conductive paste of the present invention described above, (A) an amine salt of (B) an organic polymer having a phosphoric acid group, and (C) a thermosetting resin containing formaldehyde as one component, together with copper particles having a predetermined average particle size , The conductive film formed by this conductive paste is excellent in adhesion with the ITO film. When the conductive paste contains a carboxylic acid salt of a polymer compound containing at least one primary amino group in the molecule as the component (D), adhesion with the ITO film is further improved. Therefore, the conductive film obtained from the conductive paste of the present invention has good adhesion with the ITO film surface.

≪ Substrate with conductive film &

The conductive film-adhered substrate of the present invention has a substrate having an ITO film and a conductive film formed by applying the above-described conductive paste of the present invention onto the ITO film of the substrate and curing.

Examples of the substrate main body include a glass substrate, a plastic substrate (e.g., a polyimide substrate, a polyester substrate), and a substrate made of a fiber-reinforced composite material (e.g., glass fiber reinforced resin substrate). An ITO film is formed on the surface of the base material body to constitute an ITO film-attached base material.

Examples of the method of applying the conductive paste include known methods such as screen printing, roll coating, air knife coating, blade coating, bar coating, gravure coating, die coating and slide coating. Of these, screen printing is preferred.

Curing of the coating layer is performed by heating by a method such as hot air heating or heat-radiation heating to cure the resin (thermosetting resin) in the conductive paste.

The heating temperature and the heating time may be appropriately determined depending on the properties required for the conductive film. The heating temperature is preferably 80 to 200 占 폚. If the heating temperature is 80 占 폚 or higher, the curing of the binder resin proceeds smoothly, the contact between the copper particles is improved, the conductivity is improved, and the adhesion of the conductive film to the ITO film is improved. If the heating temperature is 200 DEG C or less, the plastic substrate can be used as the substrate body, so that the degree of freedom in substrate selection can be increased.

The thickness of the conductive film formed on the ITO film is preferably 1 to 200 占 퐉, more preferably 5 to 100 占 퐉, from the viewpoint of ensuring stable electrical conductivity and maintaining the wiring shape.

The volume resistivity (also referred to as resistivity) of the conductive film is 1.0 x 10 ^-4 Cm or less. When the volume resistivity of the conductive film is 1.0 x 10 < ^-4 > If it exceeds Ω cm, it may become difficult to use it as a conductor for electronic devices. The volume resistivity of the conductive film can be obtained as follows. The electric resistance value of the conductive film was measured using a resistance value meter (trade name: Milli Om HiTester, manufactured by Keithley Co., Ltd.), and the sectional area of the conductive film was measured using a contact type shape measuring device (trade name: Surfcom 130A, . Then, the volume resistivity (specific resistance, unit: 占 ㎝ m) is calculated from the electrical resistance value, cross-sectional area, and length of the conductive film.

The adhesion of the conductive film to the ITO film surface is preferably 60/100 or more as measured by a cross-cut method. If the adhesion to the ITO film is less than 60/100, it may become difficult to use it as a conductor for electronic devices. The measurement of the adhesion by the cross-cut method was carried out by cross-cutting the conductive film in the form of a checkerboard in accordance with the method specified in JIS K 5600-5-6, using a cellophane tape (trade name: Cellophane tape # 405, And then peeling off the conductive film. Then, the number of checkerboard scales remaining without peeling is X, and X / 100 is the measurement value of the adhesion.

Example

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. The average particle diameter of the copper particles, the thickness of the conductive film, and the volume resistivity (specific resistance) were measured using the following apparatuses, respectively.

(Average particle size)

The average particle diameter of the copper particles was determined by measuring the Feret diameter of 100 randomly selected SEM images obtained by SEM (S-4300, manufactured by Nippon Electronics Co., Ltd.) and giving an average (number average) thereof.

(Thickness of the conductive film)

The thickness of the conductive film was measured using DEKTAK3 (Veeco metrology Group).

(Volume resistivity of conductive film)

The electrical resistance value of the conductive film was measured using a resistance value meter (trade name: Milli Om HiTester, manufactured by Keithley Co., Ltd.) and measured with a contact type shape measuring device (trade name: Surfcom 130A, Were measured. Then, the volume resistivity (specific resistance, unit: 占 ㎝ m) was calculated from the electrical resistance value, sectional area and length of the conductive film.

Example 1

After 3.0 g of formic acid and 9.0 g of a 50% by mass aqueous solution of hypophosphorous acid were placed in a glass beaker, the beaker was placed in a water bath and kept at 40 캜. 5.0 g of copper particles (trade name: 1400YP, average primary diameter: 7 탆, manufactured by Mitsui Mining & Smelting Co., Ltd.) was slowly added to the beaker and stirred for 30 minutes to obtain a copper dispersion.

The resulting copper dispersion was centrifuged at a rotation speed of 3000 rpm for 10 minutes using a centrifugal separator to recover the precipitate. This precipitate was dispersed in 30 g of distilled water, and the agglomerate was again precipitated by centrifugation, and the precipitate was separated. Thereafter, the resulting precipitate was heated under a reduced pressure of -35 kPa at 80 캜 for 60 minutes to remove the residual moisture by volatilization to thereby obtain a copper particle (A-1) whose surface was surface-modified.

The surface oxygen amount of the obtained copper particle (A-1) was 0.16. This value was calculated by determining the surface oxygen concentration [atomic%] and the surface copper concentration [atomic%] by X-ray photoelectron spectroscopic analysis (ESCA5500, manufactured by ULVAC · PASA) and dividing the surface oxygen concentration by the surface copper concentration. Further, the measurement was conducted using an oxygen meter (product number: "ROH-600", manufactured by LECO), and as a result, the oxygen content in the copper particles (A-1) was 460 ppm.

Subsequently, 12 g of the obtained surface-modified copper particles (A-1) were mixed with 7.4 g of a phenol resin (trade name: REGITOON PL6220, manufactured by Mfd. Was added to the resin solution dissolved in 4.3 g of butyl ether acetate. Further, 0.006 g of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 180 (acid value: 94 mgKOH / g, amine value: 94 mgKOH / g) as a component (B) And mixed at room temperature to obtain a copper paste. The blending amount of the component (B) (amine salt of organic polymer having a phosphoric acid group) was 0.12 mass% with respect to the component (C) (phenol resin).

Example 2

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, , 0.01 g of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 144 (acid value: 46 mgKOH / g, amine value: 43 mgKOH / g) as an ingredient (B) g) were placed in a mortar and mixed at room temperature to obtain a copper paste. The blending amount of the component (B) (amine salt of the organic polymer having a phosphoric acid group) was 0.12% by mass based on the component (C) (phenol resin).

Example 3

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, , 0.05 g of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 180, manufactured by BICKEMISA) was added to this mixture, and the mixture was mixed at room temperature to obtain a copper paste. The blending amount of the component (B) (amine salt of organic polymer having a phosphoric acid group) was 1.0% by mass based on the component (C) (phenol resin).

Example 4

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, 0.08 g of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 144 (acid value: 46 mgKOH / g, amine value: 43 mgKOH / g) g) were placed in a mortar and mixed at room temperature to obtain a copper paste. The blending amount of the component (B) (amine salt of organic polymer having a phosphoric acid group) was 1.0% by mass based on the component (C) (phenol resin).

Example 5

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, , 0.125 g of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 180, manufactured by BICKEMISA) was added to this mixture, and the mixture was mixed at room temperature to obtain a copper paste. The amount of the component (B) (amine salt of the organic polymer having a phosphoric acid group) was 2.5% by mass based on the component (C) (phenol resin).

Example 6

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, 0.21 g (0.125 g as an active ingredient) of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 144, manufactured by BICKEMISA) as a component (B) was placed in a mortar and mixed at room temperature to obtain a copper paste. The amount of the component (B) (amine salt of the organic polymer having a phosphoric acid group) was 2.5% by mass based on the component (C) (phenol resin).

Example 7

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, 0.25 g of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 180, manufactured by BICKEMISA) was added to the mixture in a mortar and mixed at room temperature to obtain a copper paste. The blending amount of the component (B) (amine salt of organic polymer having a phosphoric acid group) was 5.0% by mass based on the component (C) (phenol resin).

Example 8

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, 0.42 g (0.25 g as an active ingredient) of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 144, manufactured by BICKEMISA) as a component (B) was placed in a mortar and mixed at room temperature to obtain a copper paste. The blending amount of the component (B) (amine salt of organic polymer having a phosphoric acid group) was 5.0% by mass based on the component (C) (phenol resin).

Example 9

50 g of polyethyleneimine (trade name: polyethyleneimine 1200, Mw: 1200, manufactured by Junsei Chemical Co., Ltd., Mw: 1200, amine value: 1120 mmol / g) was placed in a beaker in a water bath in which the water temperature was set to 50 ° C, 45 g of formic acid was slowly added dropwise while stirring vigorously. The pale yellow polyethyleneimine reacted vigorously with smoke and turned into a dark brown liquid. After completion of the dropwise addition, the mixture was left to stand still for 30 minutes, and the resulting polyethyleneimine salt of formic acid was recovered in a glass container.

Subsequently, 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution in which 7.4 g of a phenol resin was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate, , 0.05 g of polyethyleneimine formate as the component (D) obtained in the above procedure and 0.05 g of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 180 manufactured by BICKEMISA) were placed in a mortar, To obtain a copper paste. The blending amount of the component (D) (polyethyleneimine salt) is 0.4 mass% with respect to the component (A) (copper particle), and the amount of the component (B) (amine salt of organic polymer having a phosphoric acid group) And 1.0% by mass based on the component (C) (phenol resin).

Comparative Example 1

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution in which 7.4 g of a phenol resin as the component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate. Then, the mixture was placed in a mortar and mixed at room temperature to obtain a copper paste.

Comparative Example 2

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, 0.25 g of an amine salt of an organic polymer having no phosphoric acid group (manufactured by BICKEMISA: Disperbyk 140 (acid value: 73 mgKOH / g, amine value: 76 mgKOH / g) was used instead of the component (B) , 0.125 g) was placed in a mortar and mixed at room temperature to obtain a copper paste. The blending amount of the amine salt of the organic polymer having no phosphoric acid group was 1.0% by mass based on the component (C) (phenol resin).

Comparative Example 3

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, , 0.12 g of an amine salt of p-toluenesulfonic acid (trade name: NACURE2500, manufactured by KING INDUSTRY CO., LTD.) Was placed in a mortar and mixed at room temperature in place of the component (B) to obtain a copper paste. The blending amount of the amine salt of p-toluenesulfonic acid was 2.5% by mass based on the component (C) (phenol resin).

Comparative Example 4

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, 0.12 g of an amine salt of a compound having a phosphoric acid group that is not an organic polymer (trade name: Flysup DOM (ethanolamine salt of octyl phosphate ester) manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used instead of the component (B) And mixed at room temperature to obtain a copper paste. The compounding amount of the amine salt of the compound having a phosphate group, which is not an organic polymer, was 2.5% by weight based on the component (C) (phenol resin).

Comparative Example 5

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of a phenol resin as the component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, 0.00125 g of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 180 manufactured by BICKEMISA) was added to the mixture in a mortar, and the mixture was mixed at room temperature to obtain a copper paste. The amount of the component (B) (the amine salt of the organic polymer having a phosphoric acid group) was 0.024 mass% with respect to the component (C) (phenol resin).

Comparative Example 6

12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 was added to a resin solution obtained by dissolving 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate, 0.0021 g (0.00125 g as an active ingredient) of an amine salt of an organic polymer having a phosphoric acid group as a component (B) (Disperbyk 144, manufactured by BICKEMISA) as a component (B) was placed in a mortar and mixed at room temperature to obtain a copper paste. The amount of the component (B) (the amine salt of the organic polymer having a phosphoric acid group) was 0.024 mass% with respect to the component (C) (phenol resin).

Next, the copper pastes obtained in Examples 1 to 9 and Comparative Examples 1 to 6 were respectively coated on an ITO film (thickness: 50 nm) of a glass substrate with an ITO film formed by a sputtering method and heated at 150 占 폚 for 30 minutes Thus, a phenolic resin as the component (C) was cured to form a conductive film having a thickness of 10 占 퐉. Then, the electrical resistance value of the obtained conductive film was measured using a resistance value meter (trade name: Milliohightester, manufactured by Kislyra Co., Ltd.), and the volume resistivity (resistivity; unit? Cm) was measured. The adhesion of the conductive film was evaluated by the cross-cut method.

In the table, the blending amount of the component (B) is% by mass with respect to the component (C) (phenol resin), and the amount of the component (D) is% by mass with respect to the surface-modified copper particles (A-1).

As can be seen from Table 1, an amine salt of an organic polymer having a phosphoric acid group as a component (B) together with the surface-modified copper particles is blended in an amount of 0.1 to 100% by mass with respect to the phenol resin as the component (C) By using the copper pastes of Examples 1 to 9, it is only necessary to apply the conductive paste directly on the ITO film and cure without forming a ground layer on the ITO film and without activating the surface of the ITO film , Not only the adhesiveness to the ITO film was good but also the volume resistivity was low and sufficiently high conductivity was obtained.

Although the present invention has been described in detail with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the present invention.

This application is based on Japanese Patent Application No. 2012-065997 filed on March 22, 2012, the content of which is incorporated herein by reference.

The conductive paste of the present invention can be used for various purposes. For example, the conductive paste can be used for forming and repairing a wiring pattern in a printed wiring board or the like, interlayer wiring in a semiconductor package, bonding of a printed wiring board and an electronic component .

Claims (10)

(A) Copper particles having an average particle diameter of 10 nm to 20 탆,
(B) an amine salt of an organic polymer having a phosphoric acid group,
(C) a binder resin comprising a thermosetting resin containing formaldehyde,
Wherein the binder resin of the component (C) is contained in an amount of 5 to 40 parts by mass with respect to 100 parts by mass of the copper particles of the component (A) And 0.1 to 100 parts by mass of an amine salt of the polymer. The method according to claim 1,
Wherein the amine salt of the organic polymer of component (B) has an acid value of 10 to 200 mgKOH / g and an amine value of 10 to 200 mgKOH / g. The method according to claim 1,
Wherein the amine salt of the organic polymer of component (B) is an ammonium salt, alkylamine salt, or alkylol amine salt of an organic polymer having a phosphoric acid group. The method according to claim 1,
Wherein the binder resin of the component (C) is at least one selected from the group consisting of a phenol resin, a melamine resin, a xylene resin, and a urea resin. The method according to claim 1,
Further, a conductive paste containing (D) a carboxylic acid salt of a polymer compound having at least one primary amino group in the molecule. 6. The method of claim 5,
Wherein the component (D) is a formate salt of polyethyleneimine or a salt of polyallylamine formate. 6. The method of claim 5,
Wherein the conductive paste contains 0.05 to 5 parts by mass of the carboxylate of the polymer compound of the component (D) relative to 100 parts by mass of the copper particles of the component (A). delete delete A conductive film-attached substrate characterized by having a conductive film formed by applying the conductive paste according to any one of claims 1 to 7 onto the ITO film of a substrate having a tin-doped indium oxide (ITO) film and curing the conductive film.