JP5849805B2 - Conductive paste and substrate with conductive film - Google Patents

Description

  The present invention relates to a conductive paste and a substrate with a conductive film using the same.

  Conventionally, a method using a conductive paste containing highly conductive metal particles is known for forming wiring conductors such as electronic components and printed wiring boards. Among these, a printed wiring board is manufactured by applying a conductive paste in a desired pattern shape on an insulating base material and curing it to form a conductive film forming a wiring pattern.

  As the conductive paste, 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, a copper paste containing copper particles as metal particles is less likely to cause a migration phenomenon, so that the connection reliability of an electric circuit can be improved.

  Various characteristics are required for wiring conductors such as printed wiring boards, but the adhesion of the wiring pattern to the insulating base material has an important effect on the connection reliability of the electric circuit, so it is one of the most important characteristics. One.

  Conventionally, glass, polyethylene terephthalate (PET), polyimide (PI) and the like have been used as a base material used for a printed wiring board, but recently, insulating groups such as glass and PET are mainly used for touch panels and the like. A substrate with a transparent conductive film in which a transparent conductive film such as a tin-doped indium oxide (ITO) film is formed on a material is used. When using such a substrate with a transparent conductive film 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 a transparent conductive film in a 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 solution in which a transition metal compound is dissolved in an organic solvent is applied to the surface of the ITO film, and a heat treatment is performed to form a base layer. Is disclosed (see, for example, Patent Document 3).

  However, this method requires the formation of a foundation layer, and the process of applying a conductive paste is performed after the foundation layer is formed. Therefore, there is a problem that the number of processes increases and the workability is poor.

  Moreover, in order to improve the adhesiveness of the conductive paste applied on a transparent conductive film such as an ITO film, a method of activating the transparent conductive film surface by treating with an acidic or alkaline solution, irradiation with ultraviolet rays or electron beams A method for activating the surface of the transparent conductive film and a method for activating the surface of the transparent conductive film by performing corona treatment or plasma treatment are known (for example, see Patent Document 4).

  However, this method has a problem that the number of steps is increased and workability is poor because the step of applying the conductive paste is performed after the above-described treatment.

JP-A-5-212579 JP 2009-116452 A JP 2005-293937 A Republished Patent No. 99/59814

  In order to solve the above-described problems of the prior art, the present invention can be applied directly without forming a base layer on the ITO film and without performing a treatment for activating the ITO film surface. Providing a conductive paste that can form a conductive film that exhibits good adhesion and high conductivity only by curing, and a substrate with a conductive film that is formed using such a conductive paste With the goal.

  In order to achieve the above object, 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 phosphate group, and (C) formaldehyde as one component. A binder resin composed of a thermosetting resin, containing 5 to 40 parts by mass of the binder resin of the component (C) with respect to 100 parts by mass of the copper particles of the component (A), and the component (C). Provided is an electroconductive paste characterized by containing 0.1 to 100 parts by mass of the amine salt of the organic polymer as the component (B) with respect to 100 parts by mass of the component binder resin.

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

  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 phosphate group.

  In the conductive paste of the present invention, the binder resin as 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 (D) a carboxylate of a polymer compound having at least one primary amino group in the molecule.

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

Further, the electroconductive paste of the present invention, the (A) with respect to the copper particles 100 parts by weight of component a (D) it is preferred that the carboxylate component of the polymer compound containing 0.05 to 5 parts by weight.

  In the conductive paste of the present invention, in the particle size distribution based on the number of copper particles of the component (A), the particle size when the integrated value from the small particle size side is 10% is D10, 50%. When the particle size of D50 is 90% and the particle size is 90%, it is preferable that the D90 / D50 value is 4.0 or less and the D90 / D10 value is 3.0 or more.

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

  The present invention also includes a conductive film comprising a conductive film obtained by applying and curing the conductive paste of the present invention on the ITO film of a base material having a tin-doped indium oxide (ITO) film. A substrate is provided.

  According to the present invention, adhesion to the ITO film can be achieved without forming a base layer on the ITO film of the base material having the ITO film and without performing a treatment for activating the ITO film surface. A conductive paste capable of forming a good conductive film having high conductivity can be obtained.

  Furthermore, 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.

  Embodiments of the present invention will be described below. In addition, this invention is limited to the following description and is not interpreted.

<Conductive paste>
The conductive paste of the present invention includes (A) copper particles having an average particle diameter of 10 nm to 20 μm, (B) an amine salt of an organic polymer having a phosphate group, and (C) thermosetting containing formaldehyde as one component. A binder resin made of a functional resin, and 5 to 40 parts by mass of the binder resin of the component (C) with respect to 100 parts by mass of the copper particles of the component (A), and the binder resin of the component (C) 0.1-100 mass parts of salt of the organic polymer of the said (B) component is contained with respect to 100 mass parts. Hereinafter, each component constituting the conductive paste will be described in detail.

(A) Copper particle The copper particle of (A) component is an electroconductive component of an electroconductive paste.

  (A) The average particle diameter of the copper particle of a component is the range of 10 nm-20 micrometers. 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 fine particles, and copper composite particles can 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 containing the copper particles will be good. Moreover, if the average particle diameter of a copper particle is below an upper limit, it will become easy to produce fine wiring.

(A) As a copper particle of a component, use of the copper particle (A1)-(A5) shown below is preferable, for example.
(A1) Copper particles having an average primary particle size of 0.3 to 20 μm.
(A2) Copper composite particles in which copper hydride fine particles having an average aggregated particle size of 20 to 400 nm are attached to the surface of copper particles having an average primary particle size of 0.3 to 20 μm.
(A3) Copper hydride fine particles having an average aggregated particle size of 10 nm to 1 μm.
(A4) Copper composite particles in which copper fine particles having an average aggregate particle diameter of 20 to 400 nm are attached to the surface of copper particles having an average primary particle diameter of 1 to 20 μm.
(A5) Copper fine particles having an average aggregated particle size of 10 nm to 1 μm.

  When the copper hydride fine particles are heated, the copper hydride is converted into metallic copper to form copper fine particles. That is, the copper composite particles (A2) to which the copper hydride fine particles are attached become the copper composite particles (A4) to which the copper fine particles are attached by being heated. The copper hydride fine particles (A3) become copper fine particles (A5) when heated.

  The average particle diameter in this specification can be calculated | required as follows with the shape of an above-described copper particle. When determining the average primary particle diameter of primary particles, the Feret diameters of 100 particles randomly selected from a scanning electron microscope (hereinafter referred to as “SEM”) image are measured and averaged. Is calculated by When determining the average aggregate particle diameter of secondary particles, the Feret diameters of 100 particles randomly selected from a transmission electron microscope (hereinafter referred to as “TEM”) image were measured, and the averages were averaged. It is calculated by doing.

  Moreover, in the case of the particle | grains containing a copper particle and the copper hydride fine particle adhering to this copper particle like above-mentioned copper particle (A2), the said whole particle | grain is observed by SEM, and a copper hydride fine particle is also included. In addition, the Feret diameter is measured.

  In addition, in the particle size distribution based on the number of copper particles of the component (A), the particle size when the integrated value from the small particle size side is 10% is D10, and the particle size when 50% is D50 and 90%. When the particle diameter is D90, the value of D90 / D50 is preferably 4.0 or less and the value of D90 / D10 is preferably 3.0 or more. If the value of D90 / D50 is 4.0 or less, it becomes easy to produce a fine wiring using a conductive paste. If the value of D90 / D10 is 3.0 or more, the copper particle density in the electrically conductive film formed using electrically conductive film paste will improve, and electroconductivity will become good.

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

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

  The “surface oxygen amount” in the present invention is represented by the ratio of the surface oxygen concentration (unit: atomic%) to the surface copper concentration (unit: atomic%) of the copper particles. In addition, the surface copper concentration and surface oxygen concentration of a copper particle are calculated | required by X-ray photoelectron spectroscopy analysis. Measurements are made over a 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 sufficiently grasped.

  As the copper particles having a surface oxygen amount of 0.5 or less, “surface modified copper particles” formed by reducing the surface of the copper particles, or “composite metal copper particles having copper fine particles attached to at least a part of the surface of the copper particles” Can be preferably used.

  “Surface-modified copper particles” in the present invention are obtained by reducing the surface 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. Then, it can be produced by a wet reduction method in which (2) the pH value of the copper dispersion is adjusted to a predetermined value or less and (3) a reducing agent is added to the copper dispersion.

  The “composite metal copper particles” in the present invention are obtained by attaching metal copper fine particles to at least a part of the surface of the metal copper particles, and “copper composite particles obtained by attaching copper hydride fine particles to the surface of the metal copper particles. Is heated to convert the copper hydride fine particles into metal copper fine particles. In addition, the presence or absence of adhesion of fine particles on the surface of the metal copper particles can be confirmed by observing the SEM image. Moreover, the identification of the copper hydride fine particles adhering to the surface of the metal copper particles can be performed using an X-ray diffractometer (manufactured by Rigaku Corporation, TTR-III).

  As the metal copper particles in the copper composite particles, known copper particles generally used for conductive paste can be used, and the particle shape may be spherical or plate-like. And it is preferable that it is 0.3-20 micrometers, and, as for the average particle diameter of this metal copper particle, it is more preferable that it is 1-10 micrometers. When the average particle diameter of the copper metal particles is less than 0.3 μm, sufficient flow characteristics cannot be obtained when a conductive paste is obtained. On the other hand, when the average particle diameter of the metal copper particles exceeds 20 μm, it may be difficult to produce fine wiring by the obtained conductive paste. The average particle diameter of the copper metal particles is calculated by measuring the Feret diameters of 100 metal copper particles randomly extracted from the TEM image or SEM image, and averaging the measured values. It is a thing.

  The copper hydride fine particles in the copper composite particles are present mainly as secondary particles in which primary particles of about 1 to 20 nm are aggregated, and the particle shape may be spherical or plate-like. The average particle size of the copper hydride fine particles is preferably 20 to 400 nm, more preferably 30 to 300 nm, and still more preferably 50 to 200 nm. Most preferably, it is 80-150 nm. When the average particle diameter of the copper hydride fine particles is less than 20 nm, the copper hydride fine particles are likely to be fused and grown, and there is a possibility that defects such as cracks due to volume shrinkage may occur when the conductive film is formed. . On the other hand, when the average particle diameter of the copper hydride fine particles exceeds 400 nm, the particle surface area is not sufficient, the surface melting phenomenon is hardly caused, and it becomes difficult to form a dense conductive film. As described above, the average particle diameter of the copper hydride fine particles is calculated by measuring the particle diameters of 100 copper hydride fine particles randomly extracted from the TEM image or SEM image, and averaging the measured values. It is a thing.

  The amount of the copper hydride fine particles adhering to the surface of the metal copper particles is preferably 5 to 50% by mass, and more preferably 10 to 35% by mass of the amount of the metal copper particles. When the amount of the copper hydride fine particles is less than 5% by mass of the amount of the metal copper particles, the conductive path is not sufficiently formed between the metal copper particles, and the effect of reducing the volume resistivity of the conductive film can be sufficiently obtained. There is a risk of not. On the other hand, when the amount of copper hydride fine particles exceeds 50% by mass of the amount of metal copper particles, it becomes difficult to ensure sufficient fluidity as a conductive paste. The amount of copper hydride fine particles adhering to the surface of the metal copper particles is, for example, the copper ion concentration in the water-soluble copper compound solution before adding the reducing agent and the reaction liquid after the completion of copper hydride fine particle production. It can be calculated from the difference from the remaining copper ion concentration.

(B) Amine salt of organic polymer having phosphoric acid group The conductive paste using silver particles as the conductive particles can be cured at a low temperature and in a short time, so that polyester resin, phenoxy resin, etc. These thermoplastic resins are used as binder resins.

  On the other hand, in the case of the conductive paste of the present invention, since the copper particles of the component (A) are more easily oxidized than the silver particles, from the viewpoint of improving the reliability of the conductive film, as described later, As the binder resin of component (C), a thermosetting resin is used.

  However, when a thermosetting resin is used as the binder resin, when the conductive film is formed on the ITO film by applying a conductive paste, the adhesion of the conductive film to the ITO is inferior. The reason is that 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.

  For this reason, when forming a conductive film on an ITO film using a conductive paste using copper particles as conductive particles, a method of forming a base layer on the ITO film (see Patent Document 3), It has been necessary to improve the adhesion of the conductive film to the ITO film by taking measures such as a method of performing the activation process (see Patent Document 4).

On the other hand, in the conductive paste of the present invention, the conductive film formed using the conductive paste by blending an amine salt of an organic polymer having a phosphate group as the component (B) is an ITO film. Expresses good adhesion. There are two reasons for this.
1. (B) The part which comprises a phosphate group and an amine salt in a component expresses interaction with respect to an ITO film | membrane.
2. In the component (B), the organic polymer portion exhibits compatibility with the binder resin of the component (C). As a result, in the conductive paste, the portion of the organic polymer of the component (B) is compatible with the binder resin of the component (C), and the portion constituting the phosphate group and the amine salt of the component (B) Exhibits an interaction with the ITO film, the conductive film formed using the conductive paste exhibits good adhesion to the ITO film.
Also, by blending the component (B) having a surface active function, the interface energy between the ITO film surface and the conductive paste is reduced, and the wettability of the conductive paste to the ITO film surface is improved. Accordingly, the conductive film formed using the conductive paste exhibits good adhesion to the ITO film.

  The amine salt of the organic polymer having a phosphate group constituting the component (B) has at least one phosphate group and a portion constituting the amine salt. As described above, since the portion constituting the phosphoric acid group and the amine salt in the component (B) exhibits an interaction with the ITO film, the salt of the organic polymer has a plurality of phosphoric acid groups. The acid value and amine value satisfying the following are preferable.

  Specifically, the acid value (according to JIS K7237) is preferably 10 to 200 mgKOH / g, more preferably 30 to 100 mgKOH / g. There exists a possibility that adhesiveness with an ITO film | membrane may fall that an acid value is less than 10 mgKOH / g. When the acid value exceeds 200 mgKOH / g, the organic polymer portion has a low molecular weight having 9 or less carbon atoms, and the compatibility with the component (C) binder resin may be reduced.

  The amine value (according to JIS K7237) is preferably 10 to 200 mgKOH / g, more preferably 30 to 100 mgKOH / g. There exists a possibility that adhesiveness with an ITO film | membrane may fall that an amine titer is less than 10 mgKOH / g. If the amine value exceeds 200 mgKOH / g, the organic polymer portion has a low molecular weight of 9 or less, and the compatibility with the binder resin of component (C) may be reduced.

(B) The suitable example of the amine salt of the organic polymer which comprises a component includes the ammonium salt, alkylamine salt, or alkylolamine salt of the organic polymer which has a phosphate group.
The organic polymer portion is preferably an organic polymer having 10 or more carbon atoms, and more preferably an organic polymer having 100 or more carbon atoms. Even if it has a linear main chain, it may have a branched structure. When the organic polymer portion is a copolymer, it may be a block copolymer, an alternating copolymer, a graft copolymer, or a random copolymer. . The organic polymer part is preferably a polymer of 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 Chemie) and Disperbyk 142 (manufactured by Big Chemie).

  In the conductive paste of the present invention, the compounding amount of the amine salt of the organic polymer as the component (B) is 0.1 to 100 parts by mass with respect to 100 parts by mass of the binder resin as the component (C). That is, the compounding ratio with respect to (C) component (binder resin) of (B) component (amine salt of an organic polymer) is 0.1-100 mass%. When the blending amount of the amine salt of the organic polymer (B) is 0.1 parts by mass or more with respect to 100 parts by mass of the binder resin (C), the conductive film formed using the conductive paste Adhesiveness with the ITO film surface is improved. If the blending amount of the amine salt of the organic polymer (B) is 100 parts by mass or less with respect to 100 parts by mass of the binder resin (C), the conductivity is inhibited and the volume resistivity of the conductive film is deteriorated. Thus, a conductive film having favorable conductivity can be formed.

  The compounding amount of the amine salt of the organic polymer (B) is 0.5 to 40 parts by mass with respect to 100 parts by mass of the binder resin (C), that is, the component (B) (organic polymer). It is more preferable that the mixing ratio is 0.5 to 40% by mass with respect to the component (C) (binder resin).

(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, a binder resin made of a thermosetting resin containing formaldehyde as one component is used as the binder resin of component (C). The reason is that the reduction of the methylol group produced from formaldehyde can suppress the oxidation of the surface of the copper particles, and further the curing shrinkage proceeds to ensure the contact between the copper particles.
Examples of the thermosetting resin containing formaldehyde as one component include phenol resin, melamine resin, xylene resin, and urea resin. Of these, a phenol resin is preferred from the viewpoint of the reducing action of the methylol group and the degree of cure shrinkage. If the curing shrinkage is too large, unnecessary stress accumulates in the conductive film, causing mechanical breakdown. If the curing shrinkage is too small, sufficient contact between the copper particles cannot be ensured.

  In the conductive paste of the present invention, the blending amount of the binder resin as the component (C) is appropriately selected according to the ratio between the volume of the copper particles as the component (A) and the volume of the voids existing between the copper particles. However, it is preferably 5 to 40 parts by mass and more preferably 5 to 20 parts by mass with respect to 100 parts by mass of the copper particles of the component (A). If it is 5 mass parts or more, the fluidity | liquidity characteristic of an electrically conductive paste will become favorable. If it is 40 mass parts or less, the volume resistivity of the electrically conductive film formed using an electrically conductive paste can be restrained low.

  In the conductive paste of the present invention, the conductive paste of the present invention contains at least one primary amino group in the molecule as the component (D) in addition to the components (A) to (C). It is preferable to contain a carboxylate of the polymer compound. By containing such an amino group-containing polymer compound as component (D), the adhesion of the conductive film formed using the conductive paste to the ITO film surface is further improved. The reason is that an amino group such as a primary amino group contained in the amino group-containing polymer compound forms a bond by an acid-base reaction with an acidic group of the binder resin as the component (C), and at the same time, an ITO film This is thought to be due to the interaction with the surface.

  The amino group-containing polymer compound constituting the component (D) is a high molecular weight amine containing at least one, preferably a plurality of primary amino groups in the molecule and having a mass average molecular weight Mw of 300 to 20000. is there. 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, preferably a plurality of primary amino groups. Those according to JIS K7237 are preferably 700 to 1500 mgKOH / g, 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 these, 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 preferable.

The above amino group-containing polymer compound is obtained by reacting the amino group contained therein (primary amino group and secondary amino group and / or tertiary amino group) with a carboxylic acid to form a salt. Contained in the conductive paste. Examples of the acid that 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, etc., but the binding strength with the amino group is moderate. Therefore, carboxylic acid is preferable. Among carboxylic acids, a carboxylic acid having 10 or less carbon atoms including a carbon atom of a carbonyl group is preferable, and a carboxylic acid having 4 or less carbon atoms is particularly preferable. Specifically, formic acid is particularly preferable.
Therefore, as the carboxylic acid of the amino group-containing polymer compound, polyethyleneimine formate and polyallylamine formate are preferred, and polyethyleneimine formate is particularly preferred.

  (D) When mix | blending the carboxylate of an amino-group-containing high molecular compound as a component, 0.05-5 mass parts is preferable with respect to 100 mass parts of copper particles of (A) component, and the compounding quantity is 0. .1 to 2 parts by mass is particularly preferable. That is, the blending ratio of the component (D) (amino group-containing polymer compound carboxylate) to the component (A) (copper particles) is preferably from 0.05 to 5% by mass, and from 0.1 to 2% by mass. Is particularly preferred. If the compounding amount of the amino group-containing polymer compound carboxylate of component (D) is 0.05 parts by mass or more with respect to 100 parts by mass of copper particles of component (A), the conductive paste is used. The adhesion of the conductive film to the ITO film surface is improved. If it is 5 parts by mass or less, it is less likely to inhibit the conductivity and deteriorate the volume resistivity of the conductive film, and a conductive film having good conductivity can be formed.

(E) Other components In addition to the components (A) to (D) described above, the conductive paste of the present invention includes a solvent and various additives (leveling agent, coupling agent, viscosity adjustment as necessary). Agents, antioxidants, etc.) as long as the effects of the present invention are not impaired. In particular, in order to obtain a paste having appropriate fluidity, it is preferable to contain a solvent capable of dissolving the thermosetting resin.

  Examples of the solvent include 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 and diethylene glycol monobutyl ether acetate can be used. From the viewpoint of setting an appropriate viscosity range as the printing paste, the amount of the solvent contained in the conductive paste is preferably 1 to 10% by mass with respect to the copper particles.

  The conductive paste can be obtained by mixing the components (A) to (D) above and other components such as the solvent as necessary. When mixing each component of said (A)-(D), it can carry out, heating at the temperature which does not produce the hardening of a thermosetting resin, or volatilization of a solvent.

  The temperature during mixing and stirring is preferably 10 to 40 ° C. More preferably, it is good to set it as 20-30 degreeC. By heating to a temperature of 10 ° C. or higher when preparing the conductive paste, the viscosity of the paste can be sufficiently reduced, and stirring can be performed smoothly and sufficiently. On the other hand, if the temperature at which the conductive paste is prepared exceeds 120 ° C., the resin may be cured in the paste or the particles may be fused. In order to prevent the copper particles from being oxidized during mixing, it is preferable to mix in a container substituted with an inert gas.

  In the conductive paste of the present invention described above, (A) copper particles having a predetermined average particle size, (B) an amine salt of an organic polymer having a phosphate group, and (C) formaldehyde as one component Since the binder resin which consists of thermosetting resin to contain is contained, the electrically conductive film formed with this electrically conductive paste is excellent in adhesiveness with an ITO film | membrane. And when a conductive paste contains the carboxylate of the high molecular compound which contains at least 1 primary amino group in a molecule | numerator as (D) component, adhesiveness with an ITO film | membrane will improve further. Therefore, the conductive film obtained from the conductive paste of the present invention has good adhesion to the ITO film surface.

<Substrate with conductive film>
The base material with a conductive film of the present invention has a base material having an ITO film and a conductive film formed by applying and curing the above-described conductive paste of the present invention on the ITO film of the base material.

  Examples of the substrate main body include a glass substrate, a plastic substrate (for example, a polyimide substrate, a polyester substrate, etc.), and a substrate (for example, a glass fiber reinforced resin substrate, etc.) made of a fiber reinforced composite material. An ITO film is formed on the surface of these substrate bodies to form a substrate with an ITO film.

  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. Among these, the screen printing method is preferable.

  The coating layer is cured by heating with a method such as warm air heating or heat radiation heating to cure the resin (thermosetting resin) in the conductive paste.

  What is necessary is just to determine a heating temperature and a heating time suitably according to the characteristic calculated | required by the electrically conductive film. The heating temperature is preferably 80 to 200 ° C. If heating temperature is 80 degreeC or more, hardening of binder resin will advance smoothly, the contact between copper particles will become favorable, electroconductivity will improve, and the adhesiveness with the ITO film | membrane of an electrically conductive film will improve. If heating temperature is 200 degrees C or less, since a plastic substrate can be used as a base-material main body, the freedom degree of base-material selection increases.

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

The volume resistivity (also referred to as specific resistance) of the conductive film is preferably 1.0 × 10 ⁻⁴ Ωcm or less. When the volume resistivity of the conductive film exceeds 1.0 × 10 ⁻⁴ Ωcm, it may be difficult to use it as a conductor for electronic equipment.

  Further, the adhesion of the conductive film to the ITO film surface is preferably 60/100 or more as a value measured by a cross-cut method. When the adhesiveness with the ITO film is less than 60/100, it may be difficult to use it as a conductor for electronic equipment. In addition, the adhesiveness measurement by the cross-cut method is performed by cross-cutting the conductive film into a gob-like shape by a method defined in JIS K 5600-5-6, and then using cellophane tape (product name: cellophane tape # 405 manufactured by Nichiban Co., Ltd.). ) To remove the conductive film. The number of gobangs remaining without being peeled is X, and X / 100 is a measured value of adhesion.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples. In addition, the average particle diameter of the copper particles, the thickness of the conductive film, and the volume resistivity (specific resistance) were measured using the apparatuses shown below.

(Average particle size)
The average particle diameter of the copper particles was determined by measuring the Feret diameter of 100 particles randomly selected from SEM images obtained by SEM (manufactured by JEOL Ltd., S-4300), and calculating the average (number average). ).

(Thickness of conductive film)
The thickness of the conductive film was measured by using DEKTAK3 (manufactured by Veeco metrology group).

(Volume resistivity of conductive film)
The volume resistivity of the conductive film was measured using a four-probe type volume resistivity meter (manufactured by Mitsubishi Yuka Co., Ltd., model: lorestaIP MCP-T250).

Example 1
In a glass beaker, 3.0 g of formic acid and 9.0 g of a 50 mass% hypophosphorous acid aqueous solution were placed, and the beaker was placed in a water bath and maintained at 40 ° C. In this beaker, 5.0 g of copper particles (Mitsui Metal Mining Co., Ltd., trade name: 1400 YP, average primary particle size: 7 μm) was gradually added and stirred for 30 minutes to obtain a copper dispersion.

  The resulting copper dispersion was centrifuged at 3000 rpm for 10 minutes using a centrifuge to collect a precipitate. This precipitate was dispersed in 30 g of distilled water, and the aggregate was precipitated again by centrifugation, thereby separating the precipitate. Thereafter, the obtained precipitate was heated at 80 ° C. for 60 minutes under a reduced pressure of −35 kPa to volatilize and remove residual moisture, and the copper particles (A-1) whose particle surfaces were surface-modified Got.

  The surface oxygen content of the obtained copper particles (A-1) was 0.16. This value was calculated by obtaining the surface oxygen concentration [atomic%] and the surface copper concentration [atomic%] by X-ray photoelectron spectroscopy (manufactured by ULVAC-PHI, ESCA5500), and dividing the surface oxygen concentration by the surface copper concentration. . In addition, when it measured using the oxygen meter (the product number: "ROH-600" by LECO company), the oxygen amount in a copper particle (A-1) was 460 ppm.

  Subsequently, 12 g of the obtained surface-modified copper particles (A-1) was added to a phenol resin as a component (C) (manufactured by Gunei Chemical Co., Ltd., trade name: RESITOP PL6220, all the same in the following examples). .4 g was added to a resin solution dissolved in 4.3 g of ethylene glycol monobutyl ether acetate. Further, together with this mixture, 0.006 g of an amine salt of an organic polymer having a phosphate group as component (B) (manufactured by Big Chemie: Disperbyk 180 (acid value: 94 mgKOH / g, amine value: 94 mgKOH / g)) And mixed at room temperature to obtain a copper paste. In addition, the compounding quantity of (B) component (amine salt of the organic polymer which has a phosphoric acid group) was 0.12 mass% with respect to (C) component (phenol resin).

Example 2
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, together with this mixture, an amine salt of an organic polymer having a phosphoric acid group as component (B) (manufactured by Big Chemie: Disperbyk 142 (acid value: 46 mg KOH / g, amine value: 43 mg KOH / g)) 0.01 g ( As an active ingredient, 0.006 g) was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the compounding quantity of (B) component (amine salt of the organic polymer which has a phosphoric acid group) was 0.12 mass% with respect to (C) component (phenol resin).

Example 3
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, together with this mixture, 0.05 g of an amine salt of an organic polymer having a phosphoric acid group as component (B) (manufactured by Big Chemie: Disperbyk 180) was placed in a mortar and mixed at room temperature to obtain a copper paste. . In addition, the compounding quantity of (B) component (amine salt of the organic polymer which has a phosphoric acid group) was 1.0 mass% with respect to (C) component (phenol resin).

Example 4
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, together with this mixture, an amine salt of an organic polymer having a phosphate group as component (B) (by Big Chemie: Disperbyk 142 (acid value: 46 mgKOH / g, amine value: 43 mgKOH / g)) 0.08 g ( 0.05 g) as an active ingredient was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the compounding quantity of (B) component (amine salt of the organic polymer which has a phosphoric acid group) was 1.0 mass% with respect to (C) component (phenol resin).

Example 5
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, together with this mixture, 0.125 g of an organic polymer amine salt having a phosphate group as component (B) (by Big Chemie: Disperbyk 180) was placed in a mortar and mixed at room temperature to obtain a copper paste. . In addition, the compounding quantity of (B) component (amine salt of the organic polymer which has a phosphate group) was 2.5 mass% with respect to (C) component (phenol resin).

Example 6
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, along with this mixture, 0.21 g (0.125 g as an active ingredient) of an amine salt of an organic polymer having a phosphate group as component (B) (manufactured by Big Chemie: Disperbyk 142) is placed in a mortar at room temperature. The copper paste was obtained by mixing. In addition, the compounding quantity of (B) component (amine salt of the organic polymer which has a phosphate group) was 2.5 mass% with respect to (C) component (phenol resin).

Example 7
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, together with this mixture, 0.25 g of an amine salt of an organic polymer having a phosphate group as component (B) (manufactured by Big Chemie: Disperbyk 180) was placed in a mortar and mixed at room temperature to obtain a copper paste. . In addition, the compounding quantity of (B) component (amine salt of the organic polymer which has a phosphate group) was 5.0 mass% with respect to (C) component (phenol resin).

Example 8
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, together with this mixture, 0.42 g (0.25 g as an active ingredient) of an amine salt of an organic polymer having a phosphate group as component (B) (manufactured by Big Chemie: Disperbyk 142) is placed in a mortar at room temperature. The copper paste was obtained by mixing. In addition, the compounding quantity of (B) component (amine salt of the organic polymer which has a phosphate group) was 5.0 mass% with respect to (C) component (phenol resin).

Example 9
A glass beaker is installed in a water bath set at a water temperature of 50 ° C., and 50 g of polyethyleneimine (manufactured by Junsei Chemical Co., Ltd., trade name: polyethyleneimine 1200, Mw: 1200, amine value: 1120 mmol / g) is placed in the beaker. Then, 45 g of formic acid was slowly added dropwise with vigorous stirring. The light-yellow polyethyleneimine reacted violently with smoke and turned into a brown liquid. After completion of the dropwise addition, the mixture was stirred as it was for 30 minutes, and then the polyethyleneimine formate as a product was recovered in a glass container.

  Next, 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 in 4.3 g of ethylene glycol monobutyl ether acetate. Together with the mixture, 0.05 g of polyethyleneimine formate as component (D) obtained by the above procedure and an amine salt of an organic polymer having a phosphoric acid group as component (B) (Disperbyk 180 manufactured by Big Chemie) 05 g was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the compounding quantity of (D) component (polyethyleneimine formate) is 0.4 mass% with respect to (A) component (copper particle), (B) component (organic polymer which has a phosphate group) The compounding amount of (amine salt) was 1.0% by mass relative to component (C) (phenol resin).

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

Comparative Example 2
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, together with this mixture, an amine salt of an organic polymer having no phosphoric acid group in place of the component (B) (by Big Chemie: Disperbyk 140 (acid value: 73 mgKOH / g, amine value: 76 mgKOH / g)) 25 g (0.125 g as an active ingredient) was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the compounding quantity of the amine salt of the organic polymer which does not have a phosphoric acid group was 1.0 mass% with respect to (C) component (phenol resin).

Comparative Example 3
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, together with this mixture, 0.12 g of an amine salt of p-toluenesulfonic acid (KING INDUSTRY, trade name: NACURE 2500) is placed in a mortar instead of the component (B) and mixed at room temperature to obtain a copper paste. Obtained. In addition, the compounding quantity of the amine salt of p-toluenesulfonic acid was 2.5 mass% with respect to (C) component (phenol resin).

Comparative Example 4
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition to this mixture, in addition to the component (B), an amine salt of a compound having a phosphate group that is not an organic polymer (Daiichi Kogyo Seiyaku Co., Ltd., trade name: Plysurf DOM (ethanolamine salt of octyl phosphate ester) )) 0.12 g was put in a mortar and mixed at room temperature to obtain a copper paste. In addition, the compounding quantity of the amine salt of the compound which has a phosphoric acid group which is not an organic polymer was 2.5 mass% with respect to (C) component (phenol resin).

Comparative Example 5
A resin solution obtained by dissolving 12 g of the surface-modified copper particles (A-1) obtained in the same manner as in Example 1 and 7.4 g of phenol resin as component (C) in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, together with this mixture, 0.00125 g of an organic polymer amine salt having a phosphate group as component (B) (manufactured by Big Chemie: Disperbyk 180) was placed in a mortar and mixed at room temperature to obtain a copper paste. . In addition, the compounding quantity of (B) component (amine salt of the organic polymer which has a phosphoric acid group) was 0.024 mass% with respect to (C) component (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 in which 7.4 g of a phenol resin as a component (C) was dissolved in 4.3 g of ethylene glycol monobutyl ether acetate. In addition, together with this mixture, 0.0021 g of an organic polymer amine salt having a phosphate group as component (B) (manufactured by Big Chemie: Disperbyk 142) (0.00125 g as an active ingredient) is placed in a mortar and mixed at room temperature. Together, a copper paste was obtained. In addition, the compounding quantity of (B) component (amine salt of the organic polymer which has a phosphoric acid group) was 0.024 mass% with respect to (C) component (phenol resin).

  Next, each of the copper pastes obtained in Examples 1 to 9 and Comparative Examples 1 to 6 was applied onto an ITO film (thickness 50 nm) of a glass substrate with an ITO film formed by a sputtering method. By heating for 30 minutes, the phenol resin as the component (C) was cured to form a conductive film having a thickness of 10 μm. And the electrical resistance value of the obtained electrically conductive film was measured using the resistance value meter (the Keithley company make, brand name: milliohm Hitester), and the volume resistivity (specific resistance; unit microohm cm) was measured. Moreover, the adhesiveness of the electrically conductive film was evaluated by the cross-cut method.

表中、（Ｂ）成分の配合量は、（Ｃ）成分（フェノール樹脂）に対する質量％であり、（Ｄ）成分の配合量は、表面改質銅粒子（Ａ−１）に対する質量％である。

In the table, the amount of component (B) is mass% relative to component (C) (phenolic resin), and the amount of component (D) is mass% relative to surface-modified copper particles (A-1). .

  As can be seen from Table 1, together with the surface-modified copper particles, the amine salt of the organic polymer having a phosphate group as the component (B) is 0.1 to 100% by mass relative to the phenol resin as the component (C). By using the copper pastes of Examples 1 to 9 blended by mass%, the conductive paste is formed without forming the underlayer on the ITO film and without activating the ITO film surface. By directly applying and curing on the ITO film, the adhesiveness with the ITO film was good, the volume resistivity was low, and it had sufficiently high conductivity.

  The conductive paste of the present invention can be used for various purposes, for example, for the formation and repair of wiring patterns in printed wiring boards, interlayer wiring in semiconductor packages, and bonding between printed wiring boards and electronic components. it can.

Claims (10)

(A) copper particles having an average particle diameter of 10 nm to 20 μm;
(B) an amine salt of an organic polymer having a phosphate group;
(C) a binder resin composed of a thermosetting resin containing formaldehyde as one component,
5 to 40 parts by mass of the binder resin of the (C) component is contained with respect to 100 parts by mass of the copper particles of the (A) component, and the organic of the (B) component with respect to 100 parts by mass of the binder resin of the (C) component A conductive paste containing 0.1 to 100 parts by mass of a polymer amine salt. 2. The conductivity according to claim 1, wherein the amine salt of the organic polymer as the component (B) has an acid value of 10 to 200 mg KOH / g and an amine value of 10 to 200 mg KOH / g. paste.   The conductive paste according to claim 1 or 2, wherein the amine salt of the organic polymer as the component (B) is an ammonium salt, an alkylamine salt, or an alkylolamine salt of an organic polymer having a phosphate group. .   The electrically conductive paste in any one of Claims 1-3 whose binder resin of the said (C) component is 1 or more types selected from the group which consists of a phenol resin, a melamine resin, a xylene resin, and a urea resin. .   Furthermore, (D) The electrically conductive paste in any one of Claims 1-4 containing the carboxylate of the high molecular compound which has at least 1 primary amino group in a molecule | numerator.   The conductive paste according to claim 5, wherein the component (D) is a polyethyleneimine formate or a polyallylamine formate. Wherein (A) the relative copper particles 100 parts by weight of component (D) is 0.05 to 5 parts by weight of carboxylate of the polymer compound of the component, according to claim 5 or 6 conductive paste according to.   In the particle size distribution based on the number of copper particles of the component (A), when the integrated value from the small particle size side is 10%, the particle size is D10, and when the particle size is 50%, the particle size is D50, 90%. The conductive paste according to any one of claims 1 to 7, wherein a value of D90 / D50 is 4.0 or less and a value of D90 / D10 is 3.0 or more, when the particle diameter of D90 is D90.   The conductive paste according to claim 1, wherein the copper particles of the component (A) are copper particles having a surface oxygen content of 0.5 or less.   A conductive film comprising a conductive film obtained by applying and curing the conductive paste according to any one of claims 1 to 9 on the ITO film of a substrate having a tin-doped indium oxide (ITO) film. Substrate with film.