JP2014186902A - Production method of conductive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a conductive film in which generation of ablation can be suppressed at a deposition time of a conductive copper paste by light irradiation.SOLUTION: A production method of a conductive film using a conductive copper paste in which a thermosetting resin component or a glass frit is not blended, is characterized in that the conductive copper paste includes: a copper powder, a fine copper powder, a copper salt of an aliphatic monocarboxylic acid, a (dialkylamino)alkyl amine, a polymer binder, and a prescribed organic solvent, the polymer binder has a thermal decomposition temperature of 200-500°C, the conductive copper paste is imparted on a resin substrate, then irradiated with light in a condition in which a residual amount of the prescribed organic solvent becomes 0.1-5 mass%, and deposition is performed.

Description

  The present invention relates to a method for producing a conductive film using a conductive copper paste.

  Conventionally, a conductive metal paste has been used for the purpose of forming a wiring layer and an electrode layer on the substrate surface of an inorganic material substrate.

For example, in a solar cell manufactured using a p-type silicon substrate, an n ⁺ type semiconductor layer is formed on the substrate surface serving as a light receiving surface, and a grid-shaped n-side electrode is formed on the n ⁺ type semiconductor layer. Is produced. On the other hand, an aluminum electrode is produced as a p-side electrode on the back surface of the p-type silicon substrate. A conductive aluminum paste is used to produce the aluminum electrode on the back surface of the p-type silicon substrate. In addition, a conductive silver paste or a conductive copper paste is used for producing the grid-shaped n-side electrode.

  An antireflection film is formed on the surface of the substrate that serves as the light receiving surface of the solar cell. A grid-like opening is provided in the antireflection film, and a grid-like n-side electrode is formed in the opening. For example, in conjunction with the grid-shaped openings, a conductive copper paste is applied using screen printing to form a coating film layer of the conductive copper paste having a grid pattern. Next, the conductive film is formed by subjecting the coating film layer of the conductive copper paste to a baking treatment.

  Conventional conductive copper pastes used for forming conductive films can be broadly classified into two types: thermosetting conductive copper pastes and conductive copper pastes for firing.

  The thermosetting type conductive copper paste contains the copper powder of the conductive filler and the thermosetting resin component, and in the conductor layer, the copper powder of the conductive filler is kept in contact with each other. A cured resin is used. The cured product of the thermosetting resin also has an organic adhesive function that maintains the adhesion between the formed conductor layer and the underlying layer. The electrical contact between the copper powders of the conductive filler and the electrical contact between the copper powder and the base layer are held by the cured product of the thermosetting resin.

  The conductive copper paste for baking generally contains copper powder of a conductive filler and glass frit. By conducting the baking treatment at a high temperature, the copper powder of the conductive filler constitutes a sintered body, and at that time, the melting of the glass frit proceeds and infiltrates the entire sintered body layer of the copper powder. Maintains adhesion to the formation. That is, the glass / frit component that solidifies after melting functions as an inorganic adhesive that maintains the adhesion between the entire sintered powder layer of the copper powder and the underlying layer. The formed conductor layer is composed of a copper powder sintered body layer and a molten and solidified product of glass frit infiltrated in the layer. The electrical contact between the copper powder sintered body layer and the underlying layer is maintained by the molten and solidified product of the glass frit.

  The grid-shaped n-side electrode formed on the surface of the substrate serving as the light-receiving surface of the solar cell should have a narrow electrode width and a relatively thick electrode thickness in order to increase the light-receiving area. Therefore, an increase in wiring resistance is suppressed. Generally, the resistivity of a conductor layer produced using a thermosetting conductive copper paste is higher than the resistivity of a conductor layer produced using a conductive copper paste for firing. Therefore, in many cases, a conductive copper paste for firing is used for forming the grid-shaped n-side electrode.

  A conventional conductive copper paste, that is, a thermosetting conductive copper paste and a conductive copper paste for baking, are formed on a substrate surface that becomes a light receiving surface of a solar cell, and a grid-shaped n-side electrode is formed. However, there is still room for improvement in the following points.

  The conductor layer formed using a thermosetting conductive copper paste is essentially composed of a cured product of thermosetting resin and copper powder of conductive filler, so it is not suitable for solder bonding. It has various problems.

  In addition, in the conductor layer formed using conductive copper paste for firing, the surface of the copper powder sintered body layer is covered with a glass / frit melt. It has an essential problem of becoming an unsuitable shape.

  The above problems are caused by the fact that the thermosetting conductive copper paste has a thermosetting resin component as an essential component, and that the conductive copper paste for firing has a glass frit as an essential component. ing.

  Considering this point, a conductive material with a novel configuration that can maintain adhesion to the underlying layer and electrical contact with the underlying layer without the addition of a thermosetting resin component or glass frit. Development of copper paste is required. In particular, when it is used for forming a grid-like n-side electrode formed on the surface of a substrate serving as a light-receiving surface of a solar cell, a thermosetting resin component suitable for the production of a thick conductor layer, or glass It is necessary to develop a conductive copper paste to which no frit is added. Furthermore, when the conductive layer is formed using the conductive copper paste, the conductive layer capable of forming a conductive layer exhibiting good conductivity can be formed by selecting the temperature of the heat treatment at about 400 ° C. A copper paste is desirable.

  From this point of view, Patent Document 1 does not contain a thermosetting resin component or glass frit, and the desired copper powder, fine copper powder, copper salt of aliphatic monocarboxylic acid, (dialkylamino) A conductive copper paste containing an alkylamine and an organic solvent is disclosed.

JP 2012-28243 A

The present inventor tried to form a film (sintering) by light irradiation using pulsed radiation or infrared laser instead of baking by heating, using the conductive copper paste described in Patent Document 1. It was clarified that ablation occurred upon irradiation and a desired conductive film could not be obtained.
Then, this invention makes it a subject to provide the manufacturing method of the electrically conductive film which can suppress generation | occurrence | production of ablation at the time of film-forming of the conductive copper paste by light irradiation.

As a result of diligent research to solve the above-mentioned problems, the present inventor made a residual amount of the organic solvent within a specific range after applying the conductive copper paste on the resin base material, thereby forming a film by light irradiation. The inventors have found that ablation can be suppressed and completed the present invention.
That is, it has been found that the above-described problem can be achieved by the following configuration.

That is, the manufacturing method of the electrically conductive film using the electroconductive copper paste concerning the 1st form of the present invention,
A method for producing a conductive film using a conductive copper paste not containing a thermosetting resin component or glass frit,
The conductive copper paste is
Copper powder, fine copper powder, copper salt of aliphatic monocarboxylic acid, (dialkylamino) alkylamine, polymer binder, and first organic solvent,
The polymer binder has a thermal decomposition temperature of 200 to 500 ° C.,
The first organic solvent is a liquid at room temperature, has a boiling point of 200 ° C. or higher, but does not exceed 400 ° C., and does not contain any reactive functional groups other than hydroxyl groups. An organic solvent having a group,
The copper salt of the aliphatic monocarboxylic acid is mixed with the first organic solvent as a solution obtained by dissolving in a (dialkylamino) alkylamine, to obtain a mixed solution,
A paste-like composition in which the copper powder and the fine copper powder are dispersed in the mixed solution; and
The average particle diameter of the copper powder is selected in the range of 2 μm to 10 μm,
The average particle diameter of the fine copper powder is selected in the range of 0.2 μm to 1.0 μm,
The copper salt of the aliphatic monocarboxylic acid has a boiling point of 230 ° C. or higher, but is derived from an aliphatic monocarboxylic acid (R—COOH) that does not exceed 400 ° C. Copper salt,
The (dialkylamino) alkylamine is a liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C.
The content ratio of the copper powder and the fine copper powder, (copper powder content) :( fine copper powder content) is selected in the range of 80 parts by mass: 20 parts by mass to 60 parts by mass: 40 parts by mass. ,
The total weight of copper atoms contained in the copper salt of the aliphatic monocarboxylic acid (W _{Cu-carboxylate} ) with respect to the total weight of the copper powder and the fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) The ratio of (W _Cu-powder + W _{Cu-fine-powder} ) :( W _{Cu-carboxylate} ) is selected in the range of 100 parts by mass: 0.15 parts by mass to 100 parts by mass: 0.7 parts by mass,
The ratio of the total weight (W _Cu-powder + W _{Cu-fine-powder} ) of the copper powder and fine copper powder to the weight of the first organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu -fine-powder} ): W _{dispersion-medium} is selected in the range of 100 parts by mass: 2 parts by mass to 100 parts by mass: 10 parts by mass,
The content ratio of the aliphatic monocarboxylic acid copper salt and the (dialkylamino) alkylamine is such that (dialkylamino) alkylamine is 2.2 to 8 molecules per molecule of the aliphatic monocarboxylic acid copper salt. A paste-like composition selected in a range ratio;
After applying the conductive copper paste on the resin base material, the conductive film is formed by irradiating with light in a state where the residual amount of the first organic solvent is 0.1 to 5% by mass. It is a manufacturing method of a film | membrane.

that time,
The first organic solvent is
An alkanol having 9 to 14 carbon atoms that is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C .;
An alkanediol having 4 to 9 carbon atoms that is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C.,
A polyalkylene glycol having a molecular weight of 4000 or less, which is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C.,
A polyhydric alcohol monoalkyl ether that is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C .;
It can be selected from the group consisting of glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol.

In addition, the one aspect | mode of the manufacturing method of the electrically conductive film using the electroconductive copper paste concerning the 1st form of this invention is as follows.
A method for producing a conductive film using a conductive copper paste not containing a thermosetting resin component or glass frit,
The conductive copper paste is
Copper powder, fine copper powder, copper salt of aliphatic monocarboxylic acid, (dialkylamino) alkylamine, polymer binder, and second organic solvent,
The polymer binder has a thermal decomposition temperature of 200 to 500 ° C.,
The second organic solvent is an aliphatic polyhydric alcohol that is liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 400 ° C.
The copper salt of the aliphatic monocarboxylic acid is mixed with the second organic solvent as a solution obtained by dissolving in a (dialkylamino) alkylamine, to obtain a mixed solution,
A paste-like composition in which the copper powder and the fine copper powder are dispersed in the mixed solution; and
The average particle diameter of the copper powder is selected in the range of 2 μm to 10 μm,
The average particle diameter of the fine copper powder is selected in the range of 0.2 μm to 1.0 μm,
The copper salt of the aliphatic monocarboxylic acid has a boiling point of 230 ° C. or higher, but is derived from an aliphatic monocarboxylic acid (R—COOH) that does not exceed 400 ° C. Copper salt,
The (dialkylamino) alkylamine is a liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C.
The content ratio of the copper powder and the fine copper powder, (copper powder content) :( fine copper powder content) is selected in the range of 80 parts by mass: 20 parts by mass to 60 parts by mass: 40 parts by mass. ,
The total weight of copper atoms contained in the copper salt of the aliphatic monocarboxylic acid (W _{Cu-carboxylate} ) with respect to the total weight of the copper powder and the fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) The ratio of (W _Cu-powder + W _{Cu-fine-powder} ) :( W _{Cu-carboxylate} ) is selected in the range of 100 parts by mass: 0.15 parts by mass to 100 parts by mass: 0.7 parts by mass,
The ratio of the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the weight of the second organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu -fine-powder} ): W _{dispersion-medium} is selected in the range of 100 parts by mass: 2 parts by mass to 100 parts by mass: 10 parts by mass,
The content ratio of the aliphatic monocarboxylic acid copper salt and the (dialkylamino) alkylamine is such that (dialkylamino) alkylamine is 2.2 to 8 molecules per molecule of the aliphatic monocarboxylic acid copper salt. A paste-like composition selected in a range ratio;
After applying the conductive copper paste on the resin base material, the conductive film is formed by irradiating with light in a state where the residual amount of the second organic solvent is 0.1 to 5% by mass. It is a manufacturing method of a film | membrane.

that time,
The second organic solvent is
It is liquid at room temperature and has a boiling point of 230 ° C. or higher, but an alkanediol having 4 to 9 carbon atoms in a range not exceeding 400 ° C., is liquid at room temperature, and has a boiling point of 230 ° C. or higher, but 400 ° C. A polyalkylene glycol having a molecular weight of 4000 or less and a glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6 -It can be selected from the group consisting of hexanetriol.

In the method for producing a conductive film using the conductive copper paste according to the first aspect of the present invention,
The average particle size of the copper powder is selected in the range of 3 μm to 8 μm,
The average particle size of the fine copper powder is more preferably selected in the range of 0.3 μm to 0.8 μm.

  In particular, the content ratio of the copper powder and fine copper powder, (copper powder content): (fine copper powder content) is in the range of 75 parts by mass to 25 parts by mass to 35 parts by mass. It is desirable that it is selected.

Also, the total weight of copper atoms (W _{Cu-carboxylate} ) contained in the copper salt of the aliphatic monocarboxylic acid with respect to the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) The ratio of (W _Cu-powder + W _{Cu-fine-powder} ) :( W _{Cu-carboxylate} ) can be selected in the range of 100 parts by mass: 0.3 part by mass to 100 parts by mass: 0.5 part by mass. Preferred Ratio of the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) and the weight of the first organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu- fine-powder} ): W _{dispersion-medium} is preferably selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 4.5 parts by mass.

In particular, in one aspect of the method for producing a conductive film using the conductive copper paste according to the first aspect of the present invention, an aliphatic polyhydric alcohol is used as the second organic solvent.
The ratio of the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the weight of the second organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu-fine -powder} ): W _{dispersion-medium} is preferably selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 4.5 parts by mass.

As the aliphatic monocarboxylic acid anion having a boiling point of 230 ° C. or higher, which does not exceed 400 ° C., constituting the aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)),
It is preferable to select an anion derived from an aliphatic monocarboxylic acid having 10 to 20 carbon atoms.

The (dialkylamino) alkylamine is
(Dialkylamino) propylamine (R ′ ₂ N—CH ₂ CH ₂ CH ₂ —NH) having a total carbon number of 9 to 13 which is liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C. ₂ ) is preferably selected from the group consisting of:

  The viscosity of the conductive copper paste is preferably selected in the range of 2 Pa · s to 50 Pa · s (25 ° C.).

  In the method for producing a conductive film using the conductive copper paste according to the first aspect of the present invention, a sintering aid can be further added to the conductive copper paste.

For example, as a sintering aid, a carboxylic acid metal salt or a metal carboxylic acid complex that is a metal cation species other than copper and a carboxylic acid anion species is added,
The metal cation species other than copper is selected from the group consisting of bismuth and tin, or one or a plurality of types of metal cation species,
The carboxylic acid anion species is a carboxylic acid anion species selected from the group consisting of aliphatic monocarboxylic acids having 6 to 20 carbon atoms,
Volume of metal atoms generated by reducing the carboxylic acid metal salt or metal carboxylic acid complex V _low-mp-metal and volume of metal atoms generated by reducing the copper salt of the aliphatic monocarboxylic acid The ratio of the total V _Cu-metal , V _low-mp-metal : V _Cu-metal may be selected in a range not exceeding 2: 1.

Further, as a sintering aid, a carboxylic acid metal salt or a metal carboxylic acid complex, which is a metal cation species other than copper and a carboxylic acid anion species, is added,
The metal cation species other than copper is a mixed metal cation species formed by mixing a cation species of the first metal group and a cation species of the second metal group,
The cation species of the first metal group is selected from the group consisting of bismuth and tin, or one or more metal cation species,
The cation species of the second metal group is selected from the group consisting of zinc, aluminum, indium, silver, cobalt, titanium, nickel, manganese, or a cation species of one or more metals.
In the mixed metal cation species, the total number of metal atoms of the cation species of the second metal group is selected within a range of less than 10% with respect to the total number of metal atoms of the cation species of the first metal group. And
The carboxylic acid anion species is a carboxylic acid anion species selected from the group consisting of aliphatic monocarboxylic acids having 6 to 20 carbon atoms,
A volume sum V _low-mp-metal of metal atoms of the first metal group formed by reducing a carboxylic acid metal salt or metal carboxylic acid complex, which is a cation species of the first metal group and a carboxylic acid anion species; , Ratio of the total volume of metal atoms V _Cu-metal generated by reducing the copper salt of the aliphatic monocarboxylic acid, V _low-mp-metal : V _Cu-metal does not exceed 2: 1 It can be set as the aspect currently selected.

Moreover, the manufacturing method of the electrically conductive film using the electroconductive copper paste concerning the 2nd form of this invention is as follows.
A method for producing a conductive film using a conductive copper paste not containing a thermosetting resin component or glass frit,
The conductive copper paste is
Including copper powder, fine copper powder, copper nanoparticles, (dialkylamino) alkylamine, polymer binder, and a third organic solvent,
The polymer binder has a thermal decomposition temperature of 200 to 500 ° C.,
The third organic solvent is a liquid at room temperature, has a boiling point of 200 ° C. or higher, but does not exceed 400 ° C., and has no reactive functional groups other than hydroxyl groups. An organic solvent having a group,
The copper nanoparticles are mixed with the third organic solvent as a dispersion dispersed in (dialkylamino) alkylamine, to form a mixed solution,
A paste-like composition in which the copper powder and the fine copper powder are dispersed in the mixed solution; and
The average particle size of the copper powder is selected in the range of 2 to 10 μm,
The average particle diameter of the fine copper powder is selected in the range of 0.2 to 1.0 μm,
The average particle diameter of the copper nanoparticles is selected in the range of 10 nm to 100 nm,
The (dialkylamino) alkylamine is a liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C.
The content ratio of the copper powder and the fine copper powder, (copper powder content) :( fine copper powder content) is selected in the range of 80 parts by mass: 20 parts by mass to 60 parts by mass: 40 parts by mass. ,
The ratio of the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the weight of the third organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu -fine-powder} ): W _{dispersion-medium} is selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 10 parts by mass,
The ratio of the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the total weight of the copper nanoparticles (W _{Cu-nano-particle} ), (W _Cu-powder + W _{Cu-fine-powder} ) :( W _{Cu-nano-particle} ) is selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 15 parts by mass,
The content ratio of the copper nanoparticles and the (dialkylamino) alkylamine is the ratio of the total volume of copper nanoparticles (V _{Cu-nano-particle} ) to the volume of (dialkylamino) alkylamine (V _{dispersion-medium} ). , (V _{Cu-nano-particle} ): V _amine is a paste-like composition selected in the range of 10:50 to 10: 100;
After applying the conductive copper paste on the resin base material, the conductive film is formed by irradiating with light in a state where the residual amount of the third organic solvent is 0.1 to 5% by mass. It is a manufacturing method of a film | membrane.

that time,
The third organic solvent is
An alkanol having 9 to 14 carbon atoms that is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C .;
An alkanediol having 4 to 9 carbon atoms that is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C.,
A polyalkylene glycol having a molecular weight of 4000 or less, which is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C.
A polyhydric alcohol monoalkyl ether that is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C .;
It can be selected from the group consisting of glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol.

In addition, the one aspect | mode of the manufacturing method of the electrically conductive film using the electroconductive copper paste concerning the 2nd form of this invention is as follows.
A method for producing a conductive film using a conductive copper paste not containing a thermosetting resin component or glass frit,
The conductive copper paste is
Including copper powder, fine copper powder, copper nanoparticles, (dialkylamino) alkylamine, polymer binder, and a fourth organic solvent,
The polymer binder has a thermal decomposition temperature of 200 to 500 ° C.,
The fourth organic solvent is an aliphatic polyhydric alcohol that is liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 400 ° C.,
The copper nanoparticles are mixed with the fourth organic solvent as a dispersion liquid dispersed in (dialkylamino) alkylamine, to form a mixed liquid,
A paste-like composition in which the copper powder and the fine copper powder are dispersed in the mixed solution; and
The average particle diameter of the copper powder is selected in the range of 2 μm to 10 μm,
The average particle diameter of the fine copper powder is selected in the range of 0.2 μm to 1.0 μm,
The average particle diameter of the copper nanoparticles is selected in the range of 10 nm to 100 nm,
The (dialkylamino) alkylamine is a liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C.
The content ratio of the copper powder and the fine copper powder, (copper powder content) :( fine copper powder content) is selected in the range of 80 parts by mass: 20 parts by mass to 60 parts by mass: 40 parts by mass. ,
The ratio of the total weight of copper atoms (W _{Cu-nano-particle} ) in the copper nanoparticles to the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ), (W _Cu-powder + W _{Cu-fine-powder} ): (W _{Cu-nano-particle} ) is selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 15 parts by mass,
The ratio of the total weight (W _Cu-powder + W _{Cu-fine-powder} ) of the copper powder and fine copper powder to the weight of the fourth organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu -fine-powder} ): W _{dispersion-medium} is selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 10 parts by mass,
The content ratio of the copper nanoparticles and the (dialkylamino) alkylamine is the ratio of the total volume of copper nanoparticles (V _{Cu-nano-particle} ) to the volume of (dialkylamino) alkylamine (V _{dispersion-medium} ). , (V _{Cu-nano-particle} ): V _amine is a paste-like composition selected in the range of 10:50 to 10: 100;
After applying the conductive copper paste on the resin base material, the conductive film is formed by irradiating with light in a state where the residual amount of the fourth organic solvent is 0.1 to 5% by mass. It is a manufacturing method of a film | membrane.

that time,
The fourth organic solvent is
It is liquid at room temperature and has a boiling point of 230 ° C. or higher, but is an alkanediol having 4 to 9 carbon atoms in a range not exceeding 400 ° C. A polyalkylene glycol having a molecular weight of 4000 or less, and glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2, It is preferable to select from the group consisting of 6-hexanetriol.

In the method for producing a conductive film using the conductive copper paste according to the second aspect of the present invention,
The average particle size of the copper powder is selected in the range of 3 μm to 8 μm,
The average particle size of the fine copper powder is more preferably selected in the range of 0.3 μm to 0.8 μm.

  The content ratio of the copper powder and fine copper powder, (copper powder content): (fine copper powder content) is selected in the range of 75 parts by mass: 25 parts by mass to 65 parts by mass: 35 parts by mass. Preferably it is.

Also, the ratio of the total weight of copper atoms (W _{Cu-nano-particle} ) in the copper nanoparticles to the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) , (W _Cu-powder + W _{Cu-fine-powder} ) :( W _{Cu-nano-particle} ) is more preferably selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 8 parts by mass. .

On the other hand, the ratio of the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the weight of the third organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu-fine-powder} ): W _{dispersion-medium} is preferably selected in the range of 100 parts by mass: 3.5 parts by mass to 100 parts by mass: 5.0 parts by mass.

In particular, in one aspect of the method for producing a conductive film using the conductive copper paste according to the second aspect of the present invention, an aliphatic polyhydric alcohol is used as the fourth organic solvent.
The ratio of the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the weight of the fourth organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu-fine -powder} ): W _{dispersion-medium} is preferably selected in the range of 100 parts by mass: 3.5 parts by mass to 100 parts by mass: 5.0 parts by mass.

The (dialkylamino) alkylamine is
(Dialkylamino) propylamine (R ′ ₂ N—CH ₂ CH ₂ CH ₂ —NH) having a total carbon number of 9 to 13 which is liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C. ₂ ) is preferably selected from the group consisting of:

  The viscosity of the conductive copper paste is preferably selected in the range of 2 Pa · s to 50 Pa · s (25 ° C.).

  In the method for producing a conductive film using the conductive copper paste according to the second aspect of the present invention, a copper salt of an aliphatic monocarboxylic acid and a sintering aid are further added to the conductive copper paste. Can do.

For example, the conductive copper paste further includes a copper salt of an aliphatic monocarboxylic acid and a sintering aid,
The copper salt of the aliphatic monocarboxylic acid has a boiling point of 230 ° C. or higher, but is derived from an aliphatic monocarboxylic acid (R—COOH) that does not exceed 400 ° C. Copper salt,
The copper salt of the aliphatic monocarboxylic acid is added as a solution formed by dissolving in the (dialkylamino) alkylamine,
In the (dialkylamino) alkylamine solution of the aliphatic monocarboxylic acid copper salt, the content ratio of the aliphatic monocarboxylic acid copper salt to the (dialkylamino) alkylamine is determined as follows. Per molecule, (dialkylamino) alkylamine is selected in a ratio ranging from 2.2 to 8 molecules,
The sintering aid is a carboxylic acid metal salt or a metal carboxylic acid complex, which is a metal cation species other than copper and a carboxylic acid anion species,
The metal cation species other than copper is selected from the group consisting of bismuth and tin, or one or a plurality of types of metal cation species,
The carboxylic acid anion species is a carboxylic acid anion species selected from the group consisting of aliphatic monocarboxylic acids having 6 to 20 carbon atoms,
Ratio of the total weight of copper atoms (W _{Cu-carboxylate} ) contained in the copper salt of aliphatic monocarboxylic acid to the total weight (W _Cu-powder + W _{Cu-fine-powder} ) of the copper powder and fine copper powder , (W _Cu-powder + W _{Cu-fine-powder} ): (W _{Cu-carboxylate} ) is selected in the range of 100 parts by mass: 0.15 parts by mass to 100 parts by mass: 0.7 parts by mass,
Volume of metal atoms generated by reducing the carboxylic acid metal salt or metal carboxylic acid complex V _low-mp-metal and volume of metal atoms generated by reducing the copper salt of the aliphatic monocarboxylic acid The ratio of the total V _Cu-metal , V _low-mp-metal : V _Cu-metal may be selected in a range not exceeding 2: 1.

Further, the conductive copper paste further includes a copper salt of an aliphatic monocarboxylic acid and a sintering aid,
The copper salt of the aliphatic monocarboxylic acid has a boiling point of 230 ° C. or higher, but is derived from an aliphatic monocarboxylic acid (R—COOH) that does not exceed 400 ° C. Copper salt,
The copper salt of the aliphatic monocarboxylic acid is added as a solution formed by dissolving in (dialkylamino) alkylamine,
In the (dialkylamino) alkylamine solution of the aliphatic monocarboxylic acid copper salt, the content ratio of the aliphatic monocarboxylic acid copper salt to the (dialkylamino) alkylamine is determined as follows. Per molecule, (dialkylamino) alkylamine is selected in a ratio ranging from 2.2 to 8 molecules,
The sintering aid is a carboxylic acid metal salt or a metal carboxylic acid complex, which is a metal cation species other than copper and a carboxylic acid anion species,
The metal cation species other than copper is a mixed metal cation species formed by mixing a cation species of the first metal group and a cation species of the second metal group,
The cation species of the first metal group is selected from the group consisting of bismuth and tin, or one or more metal cation species,
The cation species of the second metal group is selected from the group consisting of zinc, aluminum, indium, silver, cobalt, titanium, nickel, manganese, or a cation species of one or more metals.
In the mixed metal cation species, the total number of metal atoms of the cation species of the second metal group is selected within a range of less than 10% with respect to the total number of metal atoms of the cation species of the first metal group. And
The carboxylic acid anion species is a carboxylic acid anion species selected from the group consisting of aliphatic monocarboxylic acids having 6 to 20 carbon atoms,
Ratio of the total weight of copper atoms (W _{Cu-carboxylate} ) contained in the copper salt of aliphatic monocarboxylic acid to the total weight (W _Cu-powder + W _{Cu-fine-powder} ) of the copper powder and fine copper powder , (W _Cu-powder + W _{Cu-fine-powder} ): (W _{Cu-carboxylate} ) is selected in the range of 100 parts by mass: 0.15 parts by mass to 100 parts by mass: 0.7 parts by mass,
A volume sum V _low-mp-metal of metal atoms of the first metal group formed by reducing a carboxylic acid metal salt or metal carboxylic acid complex, which is a cation species of the first metal group and a carboxylic acid anion species; , Ratio of the total volume of metal atoms V _Cu-metal generated by reducing the copper salt of the aliphatic monocarboxylic acid, V _low-mp-metal : V _Cu-metal does not exceed 2: 1 It can be set as the aspect currently selected.

In the method for producing a conductive film using the conductive copper paste according to the second embodiment of the present invention described above, in the aspect in which the copper salt of aliphatic monocarboxylic acid and the sintering aid are further added to the conductive copper paste. ,
As the aliphatic monocarboxylic acid anion having a boiling point of 230 ° C. or higher, which does not exceed 400 ° C., constituting the aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)),
It is desirable to select an anion derived from an aliphatic monocarboxylic acid having 10 to 20 carbon atoms.

  Furthermore, in the method for producing a conductive film using the conductive copper paste according to the first aspect of the present invention, and the method for producing the conductive film using the conductive copper paste according to the second aspect of the present invention, When selecting an aspect of adding the above-mentioned sintering aid to the conductive copper paste, the addition amount of the sintering aid is based on the above-mentioned "total surface area of copper powder and surface area of fine copper powder" as follows: It is also possible to select within the range.

That is, in one aspect of the conductive copper paste to which the sintering aid is further added,
As a sintering aid, when adding a carboxylic acid metal salt or metal carboxylic acid complex, which becomes a metal cation species other than copper and a carboxylic acid anion species,
The total number of metal atoms of the metal cation species contained in the metal carboxylate or metal carboxylate complex is 100 μmol / m ² or less with respect to the sum of the surface area of the copper powder and the surface area of the fine copper powder. It is desirable to select a range.

Moreover, in another aspect of the conductive copper paste to which the sintering aid is further added,
Carboxylic acid metal salt or metal carboxylic acid complex comprising a mixed metal cation species and a carboxylic acid anion species obtained by mixing the cation species of the first metal group and the cation species of the second metal group as a sintering aid When adding
The total number of metal atoms of the metal cation species contained in the metal carboxylate or metal carboxylate complex is 100 μmol / m ² or less with respect to the sum of the surface area of the copper powder and the surface area of the fine copper powder. It is desirable to select a range.

In the manufacturing method of the electrically conductive film using the electroconductive copper paste concerning the 1st form of this invention, The mass of the copper component which totaled the said copper powder, the said fine copper powder, and the copper salt of the said aliphatic monocarboxylic acid, The ratio of the polymer binder to the mass (copper / polymer binder) is preferably 70/30 to 98/2.
Similarly, in the manufacturing method of the electrically conductive film using the electroconductive copper paste concerning the 2nd form of this invention, the mass of the copper component which totaled the said fine copper powder and the said copper nanoparticle, and the mass of the said polymer binder The ratio (copper / polymer binder) is preferably 70/30 to 98/2.

  In the method for producing a conductive film using the conductive copper paste according to the first aspect of the present invention and the method for producing the conductive film using the conductive copper paste according to the second aspect of the present invention, the resin It is preferable that the glass transition temperature of a base material is 50-400 degreeC.

  Moreover, in the manufacturing method of the electrically conductive film using the electroconductive copper paste concerning the 1st form of this invention, and the electrically conductive copper paste using the electroconductive copper paste concerning the 2nd form of this invention, Further, copper oxide can be added to the conductive copper paste.

  Furthermore, in the method for producing a conductive film using the conductive copper paste according to the first aspect of the present invention and the method for producing the conductive film using the conductive copper paste according to the second aspect of the present invention, Silver nanoparticles can be further added to the conductive copper paste.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the electrically conductive film which can suppress generation | occurrence | production of ablation at the time of film-forming of the conductive copper paste by light irradiation can be provided.

  Hereinafter, the conductive copper paste (hereinafter also referred to as “conductive copper paste according to the present invention”) used in the method for producing a conductive film of the present invention will be described in more detail.

  The conductive copper paste according to the present invention is characterized in that it does not contain a glass frit and a thermosetting resin component that are widely used in conventional conductive copper pastes. Furthermore, the conductive copper paste according to the present invention can be formed into a film (sintered) of a conductive filler contained by performing light irradiation (for example, pulse light irradiation, scanning exposure with an infrared laser, etc.) described later. The resistivity (volume specific resistance) of the obtained conductive film is a conductor with good conductivity that is less than 10 times that of metallic copper with a resistivity of 1.673 μΩ · cm (30 ° C.). It is characterized by having advantages.

In the conductive film produced using the conductive copper paste according to the first aspect of the present invention, in order to improve the adhesion with the surface of the resin base material to which the conductive copper paste is applied, glass frit, heat Instead of using a curable resin, the copper cation (Cu ²⁺ ) contained in the mixed copper salt of aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II)) is reduced and produced. A metal copper film layer made of metal copper atoms (Cu) is used. Moreover, the copper powder selected in the range whose average particle diameter is 2 micrometers-10 micrometers and the fine copper powder selected in the range whose average particle diameter is 0.2 micrometers-1.0 micrometer are used together, Furthermore, each copper powder mutual By accumulating metal copper atoms (Cu) generated in a narrow gap near the contact site and expanding the effective contact area of the contact sites between the copper powders, The resistivity is reduced.

  In the conductive film produced using the conductive copper paste according to the second aspect of the present invention, in order to improve the adhesion with the surface of the resin base material to which the conductive copper paste is applied, glass frit, heat It replaces with utilization of curable resin, and the compounded copper nanoparticle which selects the average particle diameter in the range of 10 nm-100 nm is utilized. Moreover, the copper powder selected in the range whose average particle diameter is 2 micrometers-10 micrometers and the fine copper powder selected in the range whose average particle diameter is 0.2 micrometers-1.0 micrometer are used together, Furthermore, each copper powder mutual Copper nanoparticles are accumulated in a narrow gap near the contact area, and the effective contact area of each copper powder contact area is expanded to reduce the resistivity of the entire sintered body layer of copper powder. I am trying.

  In addition, in the conductive copper paste according to the present invention, an organic compound having a hydroxyl group that can be converted into an oxo group (═O) or a formyl group (—CHO) by oxidation as a dispersion solvent, for example, an aliphatic polyhydric acid. A monohydric alcohol or a monoalkyl ether of an aliphatic polyhydric alcohol is used. When forming a conductive film using a conductive copper paste, light irradiation described later is performed in the presence of an organic compound having a hydroxyl group, for example, an aliphatic polyhydric alcohol or a monoalkyl ether of an aliphatic polyhydric alcohol. By applying, the surface oxide film which exists slightly on the surface of copper powder and fine copper powder is reduced. As a result, the metal copper surfaces come into contact with each other at the contact portions between the copper powders, and the contact resistance at the contact portions between the copper powders can be reduced.

  In the conductive copper paste according to the second aspect of the present invention, a coated molecular layer was formed on the surface of the copper nanoparticles whose average particle diameter was selected in the range of 10 nm to 100 nm using (dialkylamino) alkylamine. Above, the form which disperse | distributes the copper nanoparticle in which this coating molecular layer is formed in the surface in an aliphatic polyhydric alcohol is employ | adopted.

In the conductive copper paste according to the first aspect of the present invention, an aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)) is once dissolved in (dialkylamino) alkylamine, and then aliphatic. A form in which an amine complex of a copper salt of monocarboxylic acid ((R—COO) ₂ Cu (II)) is formed and an amine solution of the complex is mixed into an aliphatic polyhydric alcohol is employed.

Therefore, the conductive copper paste according to the first embodiment of the present invention has, as an essential component, a copper powder having an average particle size selected in the range of 2 to 10 μm and an average particle size in the range of 0.2 μm to 1.0 μm. Fine copper powder, aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)), (dialkylamino) alkylamine used for dissolving the copper salt, thermal decomposition temperature of 200 to Polymer binder at 500 ° C., first organic solvent or second organic solvent used as a dispersion solvent, for example, alcoholic hydroxyl that can be converted to oxo group (═O) or formyl group (—CHO) by oxidation It includes an aliphatic polyhydric alcohol that is an organic solvent having a group, and the copper powder and the fine copper powder are in the form of a paste-like composition that is uniformly dispersed in the dispersion solvent.

  The conductive copper paste according to the second embodiment of the present invention is selected as an essential component, copper powder having an average particle diameter of 2 to 10 μm, and an average particle diameter of 0.2 to 1.0 μm. Fine copper powder, copper nanoparticles whose average particle size is selected in the range of 10 nm to 100 nm, (dialkylamino) alkylamine used for forming a coating molecular layer on the surface of the copper nanoparticles, and a thermal decomposition temperature of 200 to Polymer binder at 500 ° C., third or fourth organic solvent used as dispersion solvent, for example, alcoholic hydroxyl that can be converted to oxo group (═O) or formyl group (—CHO) by oxidation A paste-like composition comprising an aliphatic polyhydric alcohol, which is an organic solvent having a group, wherein the copper powder, fine copper powder, and copper nanoparticles are uniformly dispersed in the dispersion solvent There is a form.

First, the copper powder selected in the range whose average particle diameter is 2-10 micrometers used for preparation of the electroconductive copper paste which concerns on the 1st form of this invention and a 2nd form, and an average particle diameter are 0.00. Fine copper powder selected in a range of 2 μm to 1.0 μm, a polymer binder having a thermal decomposition temperature of 200 to 500 ° C., a first organic solvent or a second organic solvent, and a third organic solvent or a second The four organic solvents will be described below.
Also, an organic solvent having an alcoholic hydroxyl group, such as an aliphatic polyhydric alcohol, used as the first organic solvent or the second organic solvent, and the third organic solvent or the fourth organic solvent, or Specific examples of monoalkyl ethers of aliphatic polyhydric alcohols will be shown, and their roles in the sintering process will be described below.

The conductive film produced using the conductive copper paste of the present invention is used for producing a thick copper wiring layer or an n-side electrode layer provided on the light-receiving surface side of the solar cell. In the above application, the thickness t _layer of the conductive film to be produced is usually selected in the range of 30 μm to 80 μm. This electrically conductive film is comprised by the sintered compact layer of fine copper powder and copper powder formed by heat-baking the copper powder and fine copper powder which are contained in electroconductive copper paste. At that time, the thickness of the conductive film corresponds to the thickness of the sintered body layer in which the laminated copper powder and fine copper powder are sintered. The thickness variation of the sintered body layer in which the laminated copper powder and the fine copper powder are sintered, and the unevenness of the surface are the average particle diameter d _Cu-powder of the copper powder used and the average particle of the fine copper powder. It depends on the diameter d _{Cu-fine-powder} and the content ratio of copper powder and fine copper powder.

When copper powder and fine copper powder are uniformly dispersed, a laminated structure of copper powder and fine copper powder is formed in a form in which the gap between the copper powders is filled with fine copper powder. At this time, the thickness variation Δt _layer of the sintered powder layers (conductive film) between the copper powders formed is at most about 1/2 of the average particle diameter d _Cu-powder of the copper powder used. The surface irregularity δt _layer is at most about 1/4 of the average particle diameter d _Cu-powder of the copper powder used.

The thickness variation Δt _layer is usually (Δt _layer / t _layer ) <1/4 at most with respect to the thickness t _{layer of the} conductive film to be manufactured, and more preferably (Δt _layer / t _layer ). It is desirable that the range is ≦ 1/10. At that time, considering the _{Δt layer ≦ 1/2 · d} Cu-powder, (1/2 · d Cu-powder / t layer) <1/4, more _{preferably, (1/2 · d Cu-powder} / It is desirable to select the average particle diameter d _Al-powder of the aluminum powder so that t _layer ) ≦ 1/10. Therefore, the thickness t _layer conductive film manufactured, the average particle diameter d _Cu-powder of copper _{powder, (d Cu-powder / t} layer) <1/2, more preferably, (d _Cu- It is desirable to select the _powder / t _layer ) ≦ 1/5.

Considering this point, when the thickness t _{layer of the} conductive film to be produced is in the range of 20 μm to 100 μm, preferably in the range of 30 μm to 80 μm, it is contained in the conductive copper paste according to the present invention. The average particle diameter d _CU-powder of the copper powder is desirably selected in the range of 2 μm to 10 μm, more preferably in the range of 3 μm to 8 μm.

On the other hand, in forming a laminated structure of copper powder and fine copper powder in a form filled with fine copper powder, the average particle diameter d of fine copper powder is defined as the gap between the copper powders of average particle diameter d _Cu-powder. the _{Cu-fine-powder,} the average particle diameter d _Cu-powder of less than 1/4 of copper powder, and more preferably, it is desirable to select 1/10 following range of the average particle diameter d _Cu-powder of copper powder . Therefore, the average particle diameter d _Cu-powder is in the range of 2 to 10 [mu] m, for example, when using a copper powder is selected in the range of 3Myuemu～8myuemu, average particle diameter d _{Cu-fine-powder} of fine copper powder, It is desirable to select in the range of 0.2 μm to 1.0 μm, more preferably in the range of 0.2 μm to 0.8 μm.

  Moreover, the shape of the copper powder used is selected from the group consisting of flaky copper powder, granular copper powder, and irregular-shaped copper powder. In general, it is desirable to use granular copper powder for the purpose of suppressing variations in the thickness of the conductive film to be formed and surface irregularities. The shape of the fine copper powder can also be selected from the group consisting of flaky fine copper powder, granular fine copper powder, and irregular-shaped fine copper powder. In general, it is desirable to use granular fine copper powder for the purpose of filling gaps between copper powders with fine copper powder.

  In the present invention, by filling the gap between the copper powder with the fine copper powder, in addition to the contact area between the copper powder, the contact area between the copper powder and the fine copper powder filling the gap between the copper powder By using this, the electrical connection path between the copper powders is remarkably increased. In achieving this object, the content ratio of copper powder and fine copper powder, (copper powder content): (fine copper powder content) is 80 parts by mass: 20 parts by mass to 60 parts by mass: 40 parts by mass. It is desirable to select within the range of 75 parts by mass, more preferably within the range of 75 parts by mass to 65 parts by mass: 35 parts by mass. By selecting the content ratio of the copper powder and the fine copper powder, the gap space is reduced as the entire laminated structure of the copper powder and the fine copper powder, and the electrical connection path between the copper powders is remarkably increased.

  On the other hand, the surface of the copper powder and the fine copper powder used for the preparation of the conductive copper paste according to the present invention usually has a slight surface oxide film. When forming a sintered body layer from the laminated structure of copper powder and fine copper powder, the surface oxide film present on the surface of the copper powder and fine copper powder is reduced. Organic solvents having an alcoholic hydroxyl group, especially organic compounds having an alcoholic hydroxyl group (—OH) which can be converted to an oxo group (═O) or a formyl group (—CHO) by oxidation, for example, aliphatic In the presence of a polyhydric alcohol or a monoalkyl ether of an aliphatic polyhydric alcohol, a slight surface oxide film present on the surface of the fine copper powder or copper powder is reduced by performing a light irradiation treatment described later.

When selecting the content ratio of the copper powder and fine copper powder, the ratio of the average particle diameter d _{Cu-fine-powder of the fine} copper powder and the average particle diameter d _Cu-powder of the copper powder, When the total surface area of the fine copper powder is compared, (total surface area of the fine copper powder) >> (total surface area of the copper powder).

  The surface oxide film partially present on the surfaces of the copper powder and fine copper powder is composed of a copper oxide corresponding to copper oxide (CuO). In the conductive copper paste, an organic solvent having an alcoholic hydroxyl group used as a dispersion solvent, for example, an aliphatic polyhydric alcohol or a monoalkyl ether of an aliphatic polyhydric alcohol is a surface of copper powder or fine copper powder. Is solvated (adsorbed). For a copper oxide corresponding to copper oxide (CuO), an organic solvent having an alcoholic hydroxyl group, for example, an aliphatic polyhydric alcohol, or a monoalkyl ether of an aliphatic polyhydric alcohol has a hydroxyl group (> CH -OH) is used to form hydrogen-bonded intermolecular bonds with oxygen atoms (Cu-O-Cu) in the copper oxide. At that time, it is presumed that the reduction of the surface oxide film proceeds via the following two elementary processes.

  An organic solvent having an alcoholic hydroxyl group that can be converted into an oxo group (= O) by oxidation when subjected to light irradiation treatment described later, for example, an aliphatic polyhydric alcohol, or a monoalkyl ether of an aliphatic polyhydric alcohol Reacts with the copper oxide to cause the following oxidation / reduction reaction.

CuO + (> CH—OH) → Cu + (> C═O) + H ₂ O ↑

Therefore, in the conductive copper paste according to the present invention, an organic solvent having an alcoholic hydroxyl group, for example, an aliphatic polyhydric alcohol, used as a dispersion solvent, is oxidized by an oxo group (= O) or a formyl group (- Having a hydroxyl group (—OH) convertible to CHO), and utilizing the hydroxyl group (> CH—OH), the oxygen atom (Cu—O—Cu) in the copper oxide and the hydrogen bond type Must be capable of intermolecular bonding. In addition, in the presence of an organic solvent having an alcoholic hydroxyl group, for example, an aliphatic polyhydric alcohol, or a monoalkyl ether of an aliphatic polyhydric alcohol, an organic compound having the alcoholic hydroxyl group Solvent, for example, aliphatic polyhydric alcohol, or monohydric ether of aliphatic polyhydric alcohol, using the alcoholic hydroxyl group (> CH-OH), surface oxide film on the surface of copper powder, fine copper powder It must be solvated (adsorbed) above. That is, it is preferable to use an organic compound having an alcoholic hydroxyl group (—OH) in which the hydroxyl group (—OH) is present in the form of> CH—OH or —CH ₂ —OH.

  In the conductive copper paste according to the first aspect of the present invention and the conductive copper paste according to the second aspect, the first organic solvent or the second organic solvent, and the third organic solvent or the fourth organic solvent. As the solvent, an organic solvent that satisfies the above conditions is employed. Specifically, the first organic solvent and the third organic solvent are liquid at room temperature, and the boiling point is 200 ° C. or higher, but does not exceed 400 ° C., and preferably does not exceed 300 ° C. An organic solvent having an alcoholic hydroxyl group that does not have any reactive functional group other than the hydroxyl group is used. In addition, the second organic solvent and the fourth organic solvent are liquid at room temperature and have a boiling point of 230 ° C. or higher but not exceeding 400 ° C., preferably not exceeding 300 ° C. Use polyhydric alcohol.

  On the other hand, after the reduction of the surface oxide film on the surface of the copper powder and fine copper powder is completed, at the stage where the sintering of the copper powder and fine copper powder proceeds, the copper powder and the fine copper powder are solvated on the metal copper surface. It is desirable not to remain in the (adsorbed) state. Therefore, it is liquid at room temperature and has a boiling point of 230 ° C. or higher, but does not exceed 400 ° C., preferably does not exceed 300 ° C., or a monoalkyl of an aliphatic polyhydric alcohol. It is preferable to use ether. In general, it is liquid at room temperature and has a boiling point of 230 ° C. or higher, but it is more preferable to use an aliphatic polyhydric alcohol in a range not exceeding 400 ° C., preferably not exceeding 300 ° C.

  For example, one aspect of the conductive copper paste according to the first aspect of the present invention described above, one aspect of the conductive copper paste according to the second aspect of the present invention, a second organic solvent that satisfies the above conditions, As the fourth organic solvent, an aliphatic polyhydric alcohol that is liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 400 ° C., preferably not exceeding 300 ° C. is used.

  On the other hand, after the reduction of the surface oxide film on the surface of the copper powder and fine copper powder is completed, at the stage where the sintering of the copper powder and fine copper powder proceeds, the copper powder and the fine copper powder are solvated on the metal copper surface. It is desirable not to remain in the (adsorbed) state. Therefore, it is a liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C., preferably not exceeding 300 ° C., or a monoalkyl of an aliphatic polyhydric alcohol. It is preferable to use ether. More preferably, it is a liquid at room temperature and has a boiling point of 230 ° C. or higher, but it is desirable to use an aliphatic polyhydric alcohol in a range not exceeding 280 ° C., or a monoalkyl ether of an aliphatic polyhydric alcohol.

In the conductive copper paste according to the first aspect of the present invention and the conductive copper paste according to the second aspect of the present invention, it can be used as the first organic solvent and the third organic solvent, and is liquid at room temperature. Yes, the boiling point is 200 ° C. or higher, but does not exceed 400 ° C., and the organic compound having an alcoholic hydroxyl group (—OH) does not contain any reactive functional group other than the hydroxyl group, An organic compound having an alcoholic hydroxyl group (—OH) that can be converted into an oxo group (═O) or a formyl group (—CHO) by oxidation is formed on the surface oxide film on the surface of the copper powder or fine copper powder. It is preferably used for reduction removal. An alcoholic hydroxyl group (--convertible to an oxo group (= O) or formyl group (-CHO) by oxidation, which can be suitably used for reduction and removal of the surface oxide film on the surface of the copper powder and fine copper powder. Examples of the organic compound having OH) include the following compounds.
1-nonanol (melting point −5.5 ° C., boiling point 213.5 ° C.), 1-dodecanol (melting point 23.5 ° C., boiling point 259 ° C.), which are linear saturated aliphatic primary alcohols having 9 to 12 carbon atoms. )Such;
Oleyl alcohol (melting point: 5.5 to 7.5 ° C., boiling point: 345 to 355 ° C.), which is an unsaturated aliphatic primary alcohol having 18 carbon atoms;
Isodecyl alcohol (melting point 7 ° C., boiling point 220 ° C.), isostearyl alcohol (boiling point 265 to 275 ° C.), hexyldecanol (melting point −21 to −−), which are saturated aliphatic primary alcohols having 10 to 24 carbon atoms. 15 ° C, boiling point 300-310 ° C), 2-octyl-1-dodecanol (melting point -20 ° C, boiling point 340-360 ° C), 2-decyl-1-tetradecanol (melting point 19-20 ° C, boiling point 280-290) ° C) etc .;
2-decanol (melting point −6 to −4 ° C., boiling point 211 ° C.), 2-dodecanol (melting point 19 ° C., boiling point 250 ° C.) and the like, which are aliphatic secondary alcohols having 10 to 12 carbon atoms;
2,5-hexanediol (boiling point 216 ° C.), 2-ethyl-1,3-hexanediol (boiling point 243 ° C.), 3-methyl-1,3-butanediol (alkanediol having 4 to 9 carbon atoms) Boiling point 203 ° C.), 3-methyl-1,5-pentanediol (boiling point 250 ° C.), 2-methyl-1,8-octanediol (boiling point 290-300 ° C.), 1,2-pentanediol (boiling point 206 ° C.) 1,2-hexanediol (boiling point 223 ° C.), 1,3-nonanediol (boiling point 271 ° C.), etc .;
Polyalkylene glycols having a molecular weight in the range of 4000 or less, for example, polyalkylene glycols having a total carbon number in the range of 4 to 9, particularly polyethylene glycols such as diethylene glycol (boiling point 244 ° C.), triethylene glycol (boiling point 287 ° C. ), Polypropylene glycols such as dipropylene glycol (boiling point 232 ° C.), tripropylene glycol (boiling point 268 ° C.), etc .;
Glycerin (melting point: 17.8 ° C., boiling point: 298 ° C.), 1,2,3-butanetriol (boiling point: 290-300 ° C.), 1,2,4-butanetriol (boiling point), which are alkanetriols having 3 to 6 carbon atoms. 320-330 ° C), 1,2,5-pentanetriol (boiling point 325-335 ° C), 1,2,6-hexanetriol (melting point 25 ° C, boiling point 340-350 ° C), etc .;
Alkylene glycol monoalkyl ether, polyalkylene glycol monoalkyl ether type polyhydric alcohol monoalkyl ether, ethylene glycol monohexyl ether (boiling point 208 ° C), ethylene glycol monooctyl ether (boiling point 229 ° C), diethylene glycol monobutyl ether (boiling point) 231 ° C.), diethylene glycol monohexyl ether (boiling point 259 ° C.), diethylene glycol monooctyl ether (boiling point 272 ° C.), triethylene glycol monomethyl ether (boiling point 249 ° C.), triethylene glycol monobutyl ether (boiling point 271 ° C.), dipropylene glycol mono Propyl ether (bp 212 ° C), dipropylene glycol monobutyl ether (bp 229 ° C), tripropylene glycol Glycol monomethyl ether (boiling point 242 ° C.), such as tripropylene glycol monobutyl ether (boiling point 274 ° C.);
In the conductive copper paste according to the first aspect of the present invention, as the first organic solvent used as a dispersion solvent,
An alkanol having 9 to 14 carbon atoms that is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C .;
An alkanediol having 4 to 9 carbon atoms that is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C.,
A polyalkylene glycol having a molecular weight of 4000 or less, which is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C.,
A polyhydric alcohol monoalkyl ether that is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C.,
An oxo group by oxidation selected from the group consisting of glycerin, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol; An organic solvent having an alcoholic hydroxyl group (—OH) that can be converted into (═O) or a formyl group (—CHO) can be suitably used.

In the polyhydric alcohol monoalkyl ether that is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C., preferably not exceeding 300 ° C., the polyhydric alcohol moiety is: What is alkane polyol can use suitably. For example, among the alkane polyol monoalkyl ethers, ethylene glycol monooctyl ether (melting point: −60 or less, boiling point: 229 ° C.) can be exemplified as satisfying the above requirements. Furthermore, in the polyhydric alcohol monoalkyl ether which is liquid at room temperature and has a boiling point of 200 ° C. or higher but not exceeding 400 ° C., preferably not exceeding 300 ° C., the polyhydric alcohol A moiety that is a polyalkylene glycol (HO— (C _n H _2n —O) _m —C _n H _2n —OH) can also be used. Among the polyalkylene glycol monoalkyl ethers, triethylene glycol monobutyl ether (melting point: −48 ° C., boiling point: 271 ° C.) can be exemplified as one that satisfies the above requirements.

  Furthermore, in one aspect of the conductive copper paste according to the first aspect of the present invention described above, the aliphatic polyhydric alcohol used as the second organic solvent is a liquid at room temperature and has a boiling point of 230. It is an aliphatic polyhydric alcohol having a temperature not lower than 400 ° C. but not exceeding 400 ° C., preferably not exceeding 300 ° C. For example, the aliphatic polyhydric alcohol is a liquid at room temperature and has a boiling point of 230 ° C. or higher, but does not exceed 400 ° C., and preferably does not exceed 300 ° C. Diol, for example, one of alkanediols having 6 to 8 carbon atoms, 2-ethyl-1,3-hexanediol (melting point: −40 ° C., boiling point: 245 ° C.), or boiling point is 230 ° C. or higher , A polyalkylene glycol having a molecular weight of 4000 or less, for example, a dialkylene glycol having a total carbon number of 4 to 9 in a range not exceeding 400 ° C., preferably not exceeding 300 ° C. Melting point: −40 ° C., boiling point: 232 ° C.), tripropylene glycol (molecular weight 192, boiling point 268 ° C.), etc., and glycerin, 1,2,3- Phytantriol, 1,2,4-butanetriol, 1,2,5-pentane triol, 1,2,6-hexane triol can be suitably used. Specifically, one of the alcoholic hydroxyl groups (—OH) present in the aliphatic polyhydric alcohol is oxidized to (> CH—OH) → (> C═O) and an oxo group (═O). For example, 2-ethyl-1,3-hexanediol (melting point: −40 ° C., boiling point: 245 ° C.), glycerin and the like can be suitably used.

  The aliphatic polyhydric alcohol used as the second organic solvent is preferably used also as the fourth organic solvent in one embodiment of the conductive copper paste according to the second aspect of the present invention described above. Can do.

In the conductive copper paste according to the second aspect of the present invention, copper powder, fine copper is used in the organic solvent having the above alcoholic hydroxyl group, for example, an aliphatic polyhydric alcohol, which is used as the third organic solvent. Powder and copper nanoparticles are dispersed. Therefore, the volume of the third organic solvent (V _{dispersion-medium} ) relative to the total volume of copper powder, fine copper powder, and copper nanoparticles (V _Cu-powder + V _{Cu-fine-powder} + V _{Cu-nano-particle} ) ) Ratio, (V _Cu-powder + V _{Cu-fine-powder} + V _{Cu-nano-particle} ): V _{dispersion-medium} is in the range of 20: 6 to 20:10, preferably 20: 7 to 20: 9 It is desirable to select a range.

The organic solvent having the above-mentioned alcoholic hydroxyl group, for example, an aliphatic polyhydric alcohol, used as the third organic solvent, is used when reducing the surface oxide film on the surface of copper powder or fine copper powder. Is done. Considering this point, the ratio of the total weight of copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the weight of the third organic solvent (W _{dispersion-medium} ), (W _{Cu- powder} + W _{Cu-fine-powder} ): W _{dispersion-medium} is in the range of 100 parts by mass: 2 parts by mass to 100 parts by mass: 10 parts by mass, preferably 100 parts by mass: 3 parts by mass to 100 parts by mass: 7 parts by mass. It is desirable to select within the range of 100 parts by mass: 3.5 parts by mass to 100 parts by mass: 5.0 parts by mass.

On the other hand, in the conductive copper paste according to the first aspect of the present invention, the liquid phase includes the first organic solvent described above and a copper salt of an aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II)). A solution obtained by mixing a (dialkylamino) alkylamine solution. Copper powder and fine copper powder are dispersed in this mixed solution. Therefore, the ratio of the volume of the first organic solvent (V _{dispersion-medium} ) to the total volume of copper powder and fine copper powder (V _Cu-powder + V _{Cu-fine-powder} ), (V _Cu-powder + V _{Cu- Fine-powder} ): V _{dispersion-medium} is selected in the range of 20: 5 to 20: 9, preferably in the range of 20: 6 to 20: 8.

The organic solvent having the above-mentioned alcoholic hydroxyl group, for example, an aliphatic polyhydric alcohol, used as the first organic solvent, is used for reducing the surface oxide film on the surface of copper powder or fine copper powder. Is done. Considering this point, the ratio of the total weight of copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the weight of the first organic solvent (W _{dispersion-medium} ), (W _{Cu- powder} + W _{Cu-fine-powder} ): W _{dispersion-medium} is in the range of 100 parts by mass: 2 parts by mass to 100 parts by mass: 10 parts by mass, preferably 100 parts by mass: 3 parts by mass to 100 parts by mass: 5 parts by mass. It is desirable to select a range of parts, for example, a range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 4.5 parts by mass.

In the conductive copper paste according to the first aspect of the present invention, after preparing a (dialkylamino) alkylamine solution of an aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)), Mixed with the first organic solvent.

The copper salt of the aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II)) in the (dialkylamino) alkylamine solution is obtained from the copper salt of the aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II). ) A composition in which (dialkylamino) alkylamine is in the range of 2.2 to 8 molecules per molecule, preferably in the range of 3 to 8 molecules, more preferably in the range of 4 to 7 molecules. It is desirable that the composition be such that

The copper salt of an aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II)) generally forms a dimer having a Cu: Cu bond. When dissolved in the solvent (dialkylamino) alkylamine, the copper cation (Cu ²⁺ ) of the aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)) is converted into two molecules of (dialkylamino) Alkylamine (R ′ ₂ N—C _m H _2m —NH ₂ ) is a copper salt of an aliphatic monocarboxylic acid coordinated by utilizing a lone pair of its amino group (—NH ₂ ) (( R-COO) ₂ Cu (II)) amine complex ((R—COO) ₂ Cu (II)): 2 (R ′ ₂ N—C _m H _2m —NH ₂ )). Thereafter, when a (dialkylamino) alkylamine solution of a copper salt of an aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II)) and an aliphatic polyhydric alcohol as a dispersion solvent are mixed, the aliphatic monocarboxylic acid The amine complex of copper salt ((R—COO) ₂ Cu (II)) is dissolved in a mixed liquid of (dialkylamino) alkylamine and aliphatic polyhydric alcohol. Most of them are the first with respect to C═O of the aliphatic monocarboxylic acid anion (R—COO ⁻ ) of the amine complex of the aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)). The organic solvent having the above-mentioned alcoholic hydroxyl group, for example, the hydroxyl group (> CH—OH) of the aliphatic polyhydric alcohol of the second organic solvent is used as an organic solvent for the hydrogen bonding type intermolecular bond. Formed and solvated.

  When light irradiation which will be described later is performed, an organic solvent having the above-mentioned alcoholic hydroxyl group represented by the following reaction formula, for example, an oxo group (> C-OH) of a hydroxyl group (> CH—OH) of an aliphatic polyhydric alcohol = O) and the reduction reaction of the aliphatic monocarboxylic acid copper amine complex proceeds.

_{(R-COO) 2 Cu (} II): 2 (R '2 NC m H 2m -NH 2) + (> CH-OH)
→ 2R-COOH + (Cu ( 0): 2 (R '2 NC m H 2m -NH 2)) + (> C = O)

On the other hand, the metal copper atom produced | generated by the reduction | restoration of the amine complex of this aliphatic monocarboxylic acid copper becomes a shape which (dialkylamino) alkylamine coordinated two molecules initially. When (dialkylamino) alkylamine functions as a bidentate ligand, a metal copper atom (Cu (0): 2) coordinated with two (dialkylamino) alkylamine molecules of the bidentate ligand (R ′ ₂ NC _m H _2m —NH ₂ ) can be dispersed in a dispersion solvent, while (dialkylamino) alkylamine is present in the periphery when functioning as a monodentate ligand ( Dialkylamino) alkylamine or an aliphatic polyhydric alcohol in a dispersion solvent is further coordinated, for example, a metal copper atom (Cu (0)) coordinated with 4 molecules of a monodentate (dialkylamino) alkylamine : Disperse in a dispersion solvent as 4 (R ′ ₂ NC _m H _2m —NH ₂ ).

In the state where the concentration of (dialkylamino) alkylamine dissolved in the liquid phase is sufficiently high, even when (dialkylamino) alkylamine functioning as a bidentate ligand is used, bidentate metallic copper atoms (dialkylamino) alkylamine 2 molecule ligand is coordinated (Cu (0): 2 ( R '2 NC m H 2m -NH 2) are corresponding parts, (dialkylamino) alkyl It is converted into a metal copper atom (Cu (0): 4 (R ′ ₂ NC _m H _2m —NH ₂ ) coordinated with four amine molecules.

On the other hand, (dialkylamino) alkylamine is coordinated to fine copper powder and metal copper atoms exposed on the surface of copper powder by utilizing the lone pair of amino group (—NH ₂ ). Make a realistic bond.

On the other hand, when light irradiation described later is applied, reduction of the surface oxide film on the surface of copper powder and fine copper powder proceeds, and (dialkylamino) alkylamine is coordinated to the copper metal atom on the surface to be formed (adsorption) As a result, the amount of (dialkylamino) alkylamine dissolved in the liquid phase is reduced. The metal copper atoms (dialkylamino) alkylamine 4 molecule is coordinated (Cu (0): If _{4 (R '2 NC m H} 2m -NH 2) generation of advances, dissolved in the liquid phase The amount of (dialkylamino) alkylamine is reduced.

  In addition, when the boiling point of the (dialkylamino) alkylamine is lower than the boiling point of the organic solvent having the above-mentioned alcoholic hydroxyl group of the first organic solvent, for example, the aliphatic polyhydric alcohol of the second organic solvent, In particular, the transpiration rate of (dialkylamino) alkylamine is excellent. The concentration of (dialkylamino) alkylamine dissolved in the liquid phase decreases.

  (Dialkylamino) alkylamine, which is coordinated (adsorbed) to metal copper atoms exposed on the surface of copper powder and fine copper powder, and (dialkylamino) alkylamine dissolved in the liquid phase Is in a dissociation equilibrium state. Therefore, when the concentration of (dialkylamino) alkylamine dissolved in the liquid phase falls below a certain level, a coordinated bond (adsorption) is formed on the copper metal atoms exposed on the surfaces of the copper powder and fine copper powder. The dissociation of (dialkylamino) alkylamine proceeds.

  Further, the metal copper atom coordinated by four molecules of (dialkylamino) alkylamine is also dissolved in the liquid phase with (dialkylamino) alkylamine coordinated to the metal copper atom (dialkylamino). ) Alkylamine is in dissociation equilibrium. Therefore, when the concentration of (dialkylamino) alkylamine dissolved in the liquid phase is below a certain level, dissociation of (dialkylamino) alkylamine coordinated to the metal copper atom proceeds.

For example, coordinated (dialkylamino) alkylamine is reduced to 2 molecules, metallic copper atom (Cu (0): 2 ( R '2 NC m H 2m -NH 2) is copper powder, fine copper powder When the metal copper atoms exposed on the surface of the metal are in contact with each other, a metal bond is formed between the metal copper atoms, and the metal copper atoms are fixed. metallic copper atoms derived from monocarboxylic copper (Cu (0): 2 ( R '2 NC m H 2m -NH 2) occurs sticking, then coordinated to the fixed metal copper atoms (dialkyl When the amino) alkylamine is released, the metal copper atom (Cu (0): 2 (R ' ₂ NC _m H _2m -NH ₂ ) derived from the aliphatic monocarboxylic acid copper is further fixed. Aggregates of metallic copper atoms derived from aliphatic monocarboxylic acid copper are formed using metallic copper atoms exposed on the surface of the copper powder as nuclei.

  The above phenomenon is remarkably promoted as the dispersion density of metal copper atoms coordinated by four (dialkylamino) alkylamine molecules dispersed in the liquid phase increases. In other words, the transpiration of the organic solvent having the above-mentioned alcoholic hydroxyl group of the (dialkylamino) alkylamine and the first organic solvent constituting the liquid phase, for example, the aliphatic polyhydric alcohol of the second organic solvent As the process proceeds, the above phenomenon is significantly promoted.

  When transpiration progresses and the volume of the liquid phase decreases (concentration progresses), the liquid phase is composed of fine copper powder, a narrow gap around the contact area between the copper powders, resin base material and fine copper powder, copper powder The liquid phase is agglomerated in a narrow gap around the contact area. Therefore, as the liquid phase is concentrated, the dispersion concentration of metallic copper atoms coordinated with (dialkylamino) alkylamine is increased, and as a result, fine copper powder, a narrow gap around the contact area between the copper powder, Aggregation of metal copper atoms proceeds preferentially in a narrow gap around the contact portion between the resin base material, the fine copper powder, and the copper powder.

  Therefore, the narrow gap around the contact area between the fine copper powder and the copper powder, the narrow gap around the contact area between the resin base material and the fine copper powder, and the copper powder is embedded with the aggregate of the metal copper atoms. It becomes. Then, when firing proceeds, the fine copper powder, around the contact portion of the copper powder, around the resin base material and the fine copper powder, around the contact portion of the copper powder, the aggregate of the metal copper atoms, the fine copper powder, Integration with copper powder proceeds. As a result, the contact area of the fine copper powder, the contact area between the copper powders, the contact area between the resin base material and the fine copper powder, and the copper powder is increased.

  Of course, the metal copper film layer covering the surface of the resin substrate exhibits excellent adhesion. In particular, in the part where the copper powder contacts the surface of the resin base material, a copper copper aggregate is partially formed on the surface of the copper powder. As the process proceeds, bonds between metal atoms are formed.

  In the conductive copper paste according to the first aspect of the present invention, by utilizing the above phenomenon, in the sintered body between the fine copper powder and the copper powder, the contact at the contact area between the fine copper powder and the copper powder, The area has been expanded. Moreover, the effective contact area is expanded also in the contact part of a resin base material, fine copper powder, and copper powder.

Considering the mechanism, the sum of the volume of copper powder and fine copper powder for _{(V Cu-powder + V Cu} -fine-powder), the total volume of the metallic copper atoms derived from an aliphatic monocarboxylic acid copper (V _Cu- The ratio of ( _metal ), (V _Cu-powder + V _{Cu-fine-powder} ) :( V _Cu-metal ) is in the range of 100: 0.15 to 100: 0.7, more preferably 100: 0.3 to A range of 100: 0.5 is desirable. In other words, the total number of copper atoms contained in aliphatic monocarboxylic acid copper (M _{Cu-carboxylate} ) relative to the sum of metal copper atoms in copper powder and fine copper powder (M _Cu-powder + M _{Cu-fine-powder} ) The ratio, (M _Cu-powder + M _{Cu-fine-powder} ) :( M _{Cu-carboxylate} ), is in the range of 100: 0.15 to 100: 0.7, more preferably 100: 0.3 to 100: 0. Desirably, the range is .5. That is, the total weight of copper atoms contained in aliphatic monocarboxylic acid copper (W _{Cu-carboxylate} ) with respect to the total weight of copper metal and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) The ratio of (W _Cu-powder + W _{Cu-fine-powder} ) :( W _{Cu-carboxylate} ) is in the range of 100 parts by mass: 0.15 parts by mass to 100 parts by mass: 0.7 parts by mass, more preferably It is desirable to set it as the range of 100 mass parts: 0.3 mass part-100 mass parts: 0.5 mass part.

  On the other hand, the (dialkylamino) alkylamine used for dissolution of copper aliphatic monocarboxylate needs to evaporate when subjected to light irradiation described later, like the aliphatic polyhydric alcohol of the dispersion solvent. Therefore, it is preferable to use a (dialkylamino) alkylamine that is liquid at room temperature and has a boiling point of 230 ° C. or higher but does not exceed 300 ° C. More preferably, it is desirable to use (dialkylamino) alkylamine which is liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 280 ° C.

  Further, the boiling point of the (dialkylamino) alkylamine is lower than the boiling point of the organic solvent having an alcoholic hydroxyl group of the first organic solvent, for example, the aliphatic polyhydric alcohol of the second organic solvent. In addition, it is desirable to select an organic solvent having an alcoholic hydroxyl group as the first organic solvent, for example, a combination of an aliphatic polyhydric alcohol and a (dialkylamino) alkylamine as the second organic solvent. More preferably, the boiling point of the (dialkylamino) alkylamine is lower than the boiling point of the organic solvent having an alcoholic hydroxyl group of the first organic solvent, for example, the aliphatic polyhydric alcohol of the second organic solvent. It is desirable to select a combination of the first organic solvent (or the second organic solvent) and the (dialkylamino) alkylamine so that the difference is at least within 30 ° C., preferably within 20 ° C.

In addition, in the organic solvent having an alcoholic hydroxyl group of the first organic solvent, for example, the aliphatic polyhydric alcohol of the second organic solvent, the (dialkylamino) alkylamine is derived from an aliphatic monocarboxylic acid copper when coordinated to the metal of copper atoms, by using the lone pairs of the amino (-NH _2), can be formed a coordinative bond, in particular, its amino group (-NH ₂₎ It is desirable to function as a bidentate ligand using a dialkylamino group (—NR ′ ₂ ).

In the conductive copper paste according to the first aspect of the present invention, (dialkylamino) alkylamine (R ′ ₂ N—C _m H _2m —NH ₂ ) used for dissolution of copper aliphatic monocarboxylate is used at room temperature. It is preferable to use a (dialkylamino) alkylamine having 9 to 13 carbon atoms, which is a liquid. In particular, by utilizing the amino group (—NH ₂ ) and dialkylamino group (—NR ′ ₂ ), the (dialkylamino) propylamine (R ' ₂ N—CH ₂ CH ₂ CH ₂ —NH ₂ ), for example, dibutylaminopropylamine (melting point: −50 ° C., boiling point: 238 ° C.) can be suitably used.

  As a combination of an organic solvent having an alcoholic hydroxyl group of the first organic solvent, for example, an aliphatic polyhydric alcohol of the second organic solvent and a (dialkylamino) alkylamine, 2-ethyl-1,3-hexanediol ( Melting point: −40 ° C., boiling point: 245 ° C.) and dibutylaminopropylamine (melting point: −50 ° C., boiling point: 238 ° C.), or dipropylene glycol (melting point: −40 ° C., boiling point: 232 ° C.) and dibutyl A combination of aminopropylamine and the like can be suitably selected.

On the other hand, an amine complex of a copper salt of an aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II)) is an organic solvent having an alcoholic hydroxyl group as a first organic solvent, for example, a second organic solvent. In the aliphatic polyhydric alcohol, upon irradiation with light described later, the (dialkylamino) alkylamine of the ligand is released, and instead, the organic solvent having an alcoholic hydroxyl group of the first organic solvent, for example, the first It is necessary that the aliphatic polyhydric alcohol of the second organic solvent is not converted into a coordinated form. For example, when an aliphatic polyhydric alcohol has a structure (—CH (OH) —CH (OH) —) in which a hydroxyl group (—OH) is present on an adjacent carbon atom, the structure is bidentately coordinated. It functions as a child and can replace two (dialkylamino) alkylamine molecules of the ligand. In other words, the organic solvent having the alcoholic hydroxyl group of the first organic solvent, for example, the aliphatic polyhydric alcohol of the second organic solvent has a structure in which a hydroxyl group (—OH) is present on an adjacent carbon atom ( Those not containing -CH (OH) -CH (OH)-) do not function as a bidentate ligand, and thus are easily eliminated. For example, when an alkanediol having a 1,3-diol structure such as 2-ethyl-1,3-hexanediol is employed as the aliphatic polyhydric alcohol of the dispersion solvent, the above-described advantages can be obtained.

In addition, the reduction of the amine complex of the aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)) is performed by using an organic solvent having the above alcoholic hydroxyl group as the first organic solvent, for example, the second Since the mechanism using the aliphatic polyhydric alcohol of the organic solvent is used, the amine complex of the aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)) is the alcohol of the first organic solvent. It is desirable not to carry out the autolytic reduction reaction in an organic solvent having a functional hydroxyl group, for example, an aliphatic polyhydric alcohol as the second organic solvent. In the autolytic reduction reaction, generation of CO ₂ originating from the aliphatic monocarboxylate anion occurs, and foaming due to the generated CO ₂ occurs, which is not desirable in the present invention.

In the presence of the organic solvent having an alcoholic hydroxyl group of the first organic solvent, for example, the aliphatic polyhydric alcohol of the second organic solvent, when the light irradiation described below is performed, the above-described autolysis decomposition reaction is performed rather than It is desirable that the reduction reaction using an organic solvent having an alcoholic hydroxyl group, for example, an aliphatic polyhydric alcohol, proceeds preferentially. In general, the autodegradative reduction of an aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)) increases the carbon number of the aliphatic monocarboxylic acid anion and increases the reaction initiation temperature. To do. Therefore, in the conductive copper paste according to the first aspect of the present invention, the aliphatic monocarboxylic acid anion constituting the aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)) has carbon number. It is desirable to select anions derived from 10-20 aliphatic monocarboxylic acids.

On the other hand, in the mechanism described above, aliphatic monocarboxylic acid (R—COOH) is by-produced along with the reduction of the amine complex of the copper salt of aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II)). The It is desirable that the aliphatic monocarboxylic acid (R—COOH) is evaporated during the light irradiation described later. Accordingly, the boiling point of the aliphatic monocarboxylic acid (R—COOH) is 230 ° C. or higher, but does not exceed 400 ° C., preferably 230 ° C. or higher, but does not exceed 300 ° C. Is desirable. Therefore, the boiling point is 230 ° C. or higher, but does not exceed 400 ° C., preferably 230 ° C. or higher, but is derived from an aliphatic monocarboxylic acid (R—COOH) whose range does not exceed 300 ° C. It is desirable to employ a copper salt of an aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II)).

  For example, among aliphatic monocarboxylic acids having 10 to 20 carbon atoms, decanoic acid having 10 carbon atoms (boiling point: 268.4 ° C.), undecanoic acid having 11 carbon atoms (boiling point: 284 ° C.), lauric acid having 12 carbon atoms (Dodecanoic acid, boiling point: 298.9 ° C.) and the like, corresponding to those having a boiling point of 300 ° C. or lower. Among aliphatic monocarboxylic acids having 10 to 20 carbon atoms, the boiling point is 230 ° C. or higher, but those not exceeding 400 ° C. include oleic acid (boiling point: 286 ° C./100 mmHg), elaidic acid ( Boiling point: 234 ° C./15 mmHg) can be suitably used.

Specifically, as a copper salt of aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II)), for example, oleic acid copper (boiling point: 286 ° C./100 mmHg), elaidic acid ( Boiling point: 234 ° C./15 mmHg), a linear aliphatic monocarboxylic acid (R −) in which the boiling point of the carboxylic acid, such as copper elaidate, is 230 ° C. or more but not exceeding 400 ° C. It is desirable to employ an aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)) derived from (COOH).

  In the conductive copper paste according to the second aspect of the present invention, the copper nanoparticle having an average particle diameter selected in the range of 10 nm to 100 nm has a coating molecular layer made of dialkylaminoalkylamine formed on the surface thereof. In this state, it is dispersed in the above-mentioned third organic solvent. When stored at room temperature, the dialkylaminoalkylamine is dissolved in the above-mentioned third organic solvent in order to prevent dissociation of the coating agent molecular layer composed of dialkylaminoalkylamine.

That is, the dialkylaminoalkylamine is coordinated to the metallic copper atom exposed on the surface of the copper nanoparticle by utilizing a lone pair of the amino group (—NH ₂ ). . Specifically, a dispersion liquid obtained by dispersing the copper nanoparticles in dialkylaminoalkylamine is once prepared, and the amine dispersion liquid of the copper nanoparticles is mixed in a third organic solvent.

The amine dispersion of the copper nanoparticles has a ratio of the total volume of copper nanoparticles (V _{Cu-nano-particle} ) to the volume of the solvent dialkylaminoalkylamine (V _{dispersion-medium} ), (V _{Cu-nano -particle} ): V _amine is selected in the range of _{10:50 to} 10: 100, preferably in the range of _{10:50 to 10:80} .

Even in the conductive copper paste according to the second embodiment of the present invention, the dialkylaminoalkylamine is a lone electron of its amino group (—NH ₂ ) with respect to the metal copper atom exposed on the surface of the copper powder or fine copper powder. The pair is used for coordinate binding (adsorption).

  On the other hand, when light irradiation described later is applied, reduction of the surface oxide film on the surface of copper powder and fine copper powder proceeds, and (dialkylamino) alkylamine is coordinated to the copper metal atom on the surface to be formed (adsorption) As a result, the amount of (dialkylamino) alkylamine dissolved in the liquid phase is reduced.

  In addition, an organic solvent having an alcoholic hydroxyl group of the third organic solvent, for example, when the boiling point of (dialkylamino) alkylamine is lower than the boiling point of the aliphatic polyhydric alcohol of the fourth organic solvent, Because the transpiration rate of (dialkylamino) alkylamine is excellent. The concentration of (dialkylamino) alkylamine dissolved in the liquid phase decreases.

  (Dialkylamino) alkylamine, which is coordinated (adsorbed) to metal copper atoms exposed on the surface of copper powder and fine copper powder, and (dialkylamino) alkylamine dissolved in the liquid phase Is in a dissociation equilibrium state. Therefore, when the concentration of (dialkylamino) alkylamine dissolved in the liquid phase falls below a certain level, a coordinated bond (adsorption) is formed on the copper metal atoms exposed on the surfaces of the copper powder and fine copper powder. The dissociation of (dialkylamino) alkylamine proceeds.

  Also, in the coating agent molecular layer on the surface of the copper nanoparticles, the (dialkylamino) alkylamine coordinated to the metal copper atom and the (dialkylamino) alkylamine dissolved in the liquid phase are in a dissociation equilibrium. It is in a state. Therefore, when the concentration of (dialkylamino) alkylamine dissolved in the liquid phase is below a certain level, dissociation of (dialkylamino) alkylamine coordinated to the metal copper atom proceeds.

  For example, when copper nanoparticles with a substantial part of the coating molecular layer are separated from the copper metal exposed on the surface of the copper powder or fine copper powder, a metal bond is formed between the metal copper atoms. And stick. That is, with copper metal exposed on the surface of copper powder and fine copper powder as a nucleus, copper nanoparticles are fixed, and then (dialkylamino) alkylamine is further detached from the surface of the fixed copper nanoparticles. The copper nanoparticles are further fixed. Therefore, an integrated layer (aggregate) composed of a plurality of copper nanoparticles is formed using metal copper atoms exposed on the surfaces of copper powder and fine copper powder as nuclei.

  The above phenomenon is significantly promoted as the dispersion density of the copper nanoparticles dispersed in the liquid phase increases. In other words, the transpiration of the (dialkylamino) alkylamine constituting the liquid phase and the organic solvent having an alcoholic hydroxyl group of the third organic solvent, for example, the aliphatic polyhydric alcohol of the fourth organic solvent As the process proceeds, the above phenomenon is significantly promoted.

  When transpiration progresses and the volume of the liquid phase decreases (concentration progresses), the liquid phase is composed of fine copper powder, a narrow gap around the contact area between the copper powders, resin base material and fine copper powder, copper powder The liquid phase is agglomerated in a narrow gap around the contact area. Therefore, with the concentration of the liquid phase, the dispersion concentration of the copper nanoparticles increases, and as a result, the fine copper powder, the narrow gap around the contact area between the copper powder, the contact between the resin substrate and the fine copper powder, the copper powder Formation of an accumulation layer (aggregate) of copper nanoparticles preferentially proceeds in a narrow gap around the site.

  Therefore, the narrow gap around the contact area between the fine copper powder and the copper powder, the narrow gap around the contact area between the resin base material and the fine copper powder, and the copper powder is an accumulation layer (aggregate) of the copper nanoparticles. It becomes an embedded state. After that, when firing proceeds, the copper nanoparticle aggregated layer (aggregate) around the contact area between the fine copper powder, the copper powder contact area, the resin base material and the fine copper powder, and the copper powder contact area, Integration with fine copper powder and copper powder proceeds. As a result, the contact area of the fine copper powder, the contact area between the copper powders, the contact area between the resin base material and the fine copper powder, and the copper powder is increased.

  Of course, the metal copper film layer covering the surface of the resin substrate exhibits excellent adhesion. In particular, at the part where the copper powder contacts the surface of the resin base material, a copper nanoparticle aggregate (integrated layer) is also partially formed on the surface of the copper powder. However, when integration proceeds, bonds between metal atoms are formed.

Considering this mechanism, the ratio of the total volume of copper nanoparticles (V _{Cu-nano-particle} ) to the total volume of copper powder and fine copper powder (V _Cu-powder + V _{Cu-fine-powder} ), (V _Cu-powder + V _{Cu-fine-powder} ) :( V _{Cu-nano-particle} ) is in the range of 100: 3 to 100: 15, preferably in the range of 100: 3 to 100: 8, more preferably 100: A range of 3 to 100: 5 is desirable. In other words, the ratio of the total number of copper atoms contained in copper nanoparticles (M _{Cu-nano-particle} ) to the sum of metal copper atoms in copper powder and fine copper powder (M _Cu-powder + M _{Cu-fine-powder} ) , (M _Cu-powder + M _{Cu-fine-powder} ) :( M _{Cu-nano-particle} ) is in the range of 100: 3 to 100: 15, preferably in the range of 100: 3 to 100: 8, more preferably , 100: 3 to 100: 5 is desirable. That is, the total weight of copper atoms (W _{Cu-nano-particle} ) in the copper nanoparticles relative to the total weight of copper and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) The ratio (W _Cu-powder + W _{Cu-fine-powder} ) :( W _{Cu-nano-particle} ) is in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 15 parts by mass, preferably 100 parts by mass: It is desirable to set it as the range of 3 mass parts-100 mass parts: 8 mass parts, More preferably, it is the range of 100 mass parts: 3 mass parts-100 mass parts: 5 mass parts.

  On the other hand, (dialkylamino) alkylamine used for the preparation of copper nanoparticle amine dispersion is an organic solvent having an alcoholic hydroxyl group of a third organic solvent, for example, an aliphatic polyvalent of a fourth organic solvent. Like alcohol, it is necessary to evaporate when performing the light irradiation mentioned later. Therefore, it is preferable to use a (dialkylamino) alkylamine that is liquid at room temperature and has a boiling point of 230 ° C. or higher but does not exceed 300 ° C. More preferably, it is desirable to use (dialkylamino) alkylamine which is liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 280 ° C.

  Furthermore, the boiling point of the (dialkylamino) alkylamine is lower than the boiling point of the organic solvent having an alcoholic hydroxyl group of the third organic solvent, for example, the aliphatic polyhydric alcohol of the fourth organic solvent. In addition, it is desirable to select a combination of an organic solvent having an alcoholic hydroxyl group as the third organic solvent, for example, an aliphatic polyhydric alcohol as the fourth organic solvent and a (dialkylamino) alkylamine. More preferably, the boiling point of the (dialkylamino) alkylamine is lower than the boiling point of the organic solvent having an alcoholic hydroxyl group of the third organic solvent, for example, the aliphatic polyhydric alcohol of the fourth organic solvent. The organic solvent having an alcoholic hydroxyl group of the third organic solvent, for example, the aliphatic polyhydric alcohol of the fourth organic solvent, so that the difference is at least within 30 ° C., preferably within 20 ° C. And a combination of (dialkylamino) alkylamines.

In addition, in the organic solvent having an alcoholic hydroxyl group of the third organic solvent, for example, the aliphatic polyhydric alcohol of the fourth organic solvent, the (dialkylamino) alkylamine is derived from the aliphatic monocarboxylic acid copper when coordinated to the metal of copper atoms, by using the lone pairs of the amino (-NH _2), can be formed a coordinative bond, in particular, its amino group (-NH ₂₎ A dialkylamino group (—NR ′ ₂ ) can be used to function as a bidentate ligand, but it is desirable.

In the conductive copper paste according to the second aspect of the present invention, (dialkylamino) alkylamine (R ′ ₂ N—C _m H _2m —NH ₂ ) used for dispersion of copper nanoparticles is liquid at room temperature. It is preferable to use a (dialkylamino) alkylamine having a total carbon number of 9 to 13. In particular, by utilizing the amino group (—NH ₂ ) and dialkylamino group (—NR ′ ₂ ), the (dialkylamino) propylamine (R ' ₂ N—CH ₂ CH ₂ CH ₂ —NH ₂ ), for example, dibutylaminopropylamine (melting point: −50 ° C., boiling point: 238 ° C.) can be suitably used.

  As a combination of an organic solvent having an alcoholic hydroxyl group as a third organic solvent, for example, an aliphatic polyhydric alcohol as a fourth organic solvent and a (dialkylamino) alkylamine, 2-ethyl-1,3-hexanediol (Melting point: −40 ° C., boiling point: 245 ° C.) and dibutylaminopropylamine (melting point: −50 ° C., boiling point: 238 ° C.) or dipropylene glycol (melting point: −40 ° C., boiling point: 232 ° C.) and dibutylamino A combination of propylamine and the like can be suitably selected.

  In addition, in the conductive copper paste according to the first aspect of the present invention, in addition to the copper salt of the aliphatic monocarboxylic acid, it is also possible to make a conductive copper paste to which the following sintering aid is added. It is.

  That is, a metal other than copper, which can generate a metal atom when reduced by performing light irradiation described later in the presence of an organic solvent having an alcoholic hydroxyl group as the first organic solvent, for example, an aliphatic polyhydric alcohol. A sintering aid can be further added to a carboxylic acid metal salt or metal carboxylic acid complex, which becomes a cation species and a carboxylic acid anion species.

In one aspect of the conductive copper paste in which the sintering aid is further added in addition to the copper salt of the aliphatic monocarboxylic acid,
In the carboxylic acid metal salt or metal carboxylic acid complex, which is added as a sintering aid and becomes a metal cation species other than copper and a carboxylic acid anion species,
The metal cation species other than copper is selected from the group consisting of bismuth and tin, or one or a plurality of types of metal cation species,
The carboxylic acid anion species is an anionic species of carboxylic acid selected from the group consisting of aliphatic monocarboxylic acids having 6 to 20 carbon atoms.

  By reducing the carboxylic acid metal salt or metal carboxylic acid complex, the metal atoms produced are the copper atoms produced by the reduction of the aliphatic monocarboxylic acid copper salt, and the contact sites between the fine copper powder and the copper powder. A narrow gap around the contact area between the resin base material and the fine copper powder or the copper powder is filled.

  By reducing the carboxylic acid metal salt or metal carboxylic acid complex, the melting point of the metal produced is 271.4 ° C. for bismuth and 232 ° C. for tin, and at least a temperature of 350 ° C. or higher is in a molten state. . Aggregates composed of these low-melting-point metal atoms generated by reducing the carboxylic acid metal salt or metal carboxylic acid complex and metal copper atoms generated by reduction of the copper salt of an aliphatic monocarboxylic acid, Alloying occurs at temperatures above the melting point of the melting point metal.

  By reducing the metal carboxylate or metal carboxylate complex, the resistivity of the metal produced is 120 μΩ · cm (20 ° C.) for bismuth and 11 μΩ · cm (20 ° C.) for tin, and the resistance of metal copper Compared with the rate of 1.673 μΩ · cm (30 ° C.), it is an order of magnitude higher value. Therefore, the alloy composed of these low melting point metals and copper has a sudden increase in resistivity as the content ratio of the low melting point metals increases. Even in a range where the content ratio of the low melting point metal is low, the resistivity of the alloy composed of the low melting point metal and copper is much higher than the resistivity of metallic copper due to the so-called alloy scattering.

  An alloy formed from an aggregate of these low melting point metal atoms generated by reducing the carboxylic acid metal salt or metal carboxylic acid complex and metal copper atoms formed by reduction of the copper salt of an aliphatic monocarboxylic acid is In order to fill a narrow gap around the contact area between the fine copper powder and the copper powder, the content ratio of the low melting point metal is increased and the contact area at the contact area between the fine copper powder and the copper powder is increased. On the other hand, as the content ratio of the low melting point metal increases, the resistivity of the formed alloy itself increases rapidly from the resistivity of metallic copper. The effect of the “increase in resistivity caused by alloying” becomes more prominent as the resistivity of the low melting point metal is higher.

  Accordingly, when the content ratio of the low melting point metal exceeds a certain level, the effect of “expansion of contact area” is offset by the effect of “increase in resistivity caused by alloying”.

In other words, it is generated by reducing the volume sum V _{low-mp-metal of} these low melting point metal atoms and the copper salt of an aliphatic monocarboxylic acid, which is generated by reducing the metal carboxylate or metal carboxylate. The ratio of the volume total V _Cu-metal of metal copper atoms, V _low-mp-metal : V _Cu-metal needs to be selected in a range not exceeding a certain level according to the type of low melting point metal. Typically, the ratio, V _low-mp-metal : V _Cu-metal, is selected at least in a range not exceeding 4: 1, usually not exceeding 2: 1, preferably not exceeding 1: 1. It is desirable to do.

In the conductive copper paste according to the first aspect of the present invention, the total number of metal atoms of the metal cation species contained in the carboxylic acid metal salt or metal carboxylic acid complex is the surface area of the copper powder and the fine copper powder. against the sum of the surface area, 100 [mu] mol / m ² or less, preferably in the range of from, 80μmol / m ² or less, more preferably in the range, 50 [mu] mol / m ² or less of the range, particularly preferably, 30 [mu] mol / m ² or less of It is desirable to select a range.

Furthermore, in another aspect of the conductive copper paste to which the sintering aid is further added,
In a carboxylic acid metal salt or metal carboxylic acid complex, which is a metal cation species other than copper and a carboxylic acid anion species, which is added as a sintering aid,
The metal cation species other than copper is a mixed metal cation species formed by mixing a cation species of the first metal group and a cation species of the second metal group,
The cation species of the first metal group is selected from the group consisting of bismuth and tin, or one or more metal cation species,
The cation species of the second metal group is selected from the group consisting of zinc, aluminum, indium, silver, cobalt, titanium, nickel, manganese, or a cation species of one or more metals.
In the mixed metal cation species, the total number of metal atoms of the cation species of the second metal group is selected within a range of less than 10% with respect to the total number of metal atoms of the cation species of the first metal group. And
The carboxylic acid anion species is an anionic species of carboxylic acid selected from the group consisting of aliphatic monocarboxylic acids having 6 to 20 carbon atoms.

  By reducing the carboxylic acid metal salt or metal carboxylic acid complex, the metal atom of the first metal group and the metal atom of the second metal group are produced by reduction of a copper salt of an aliphatic monocarboxylic acid. Along with copper atoms, the fine copper powder, a narrow gap around the contact area between the copper powders, and a narrow gap around the contact area between the resin base material and the fine copper powder, the copper powder are filled.

  By reducing the metal carboxylate or metal carboxylate complex, the melting point of the metal of the first metal group produced is 271.4 ° C. for bismuth and 232 ° C. for tin, and at least at a temperature of 350 ° C. or higher. It will be in a molten state. In addition, the melting point of the metal of the second metal group to be generated is 419.5 ° C. for zinc, 660.36 ° C. for aluminum, 156.6 ° C. for indium, 961 ° C. for silver, 1495 ° C. for cobalt, 1667 ° C. for titanium, Nickel is 1456 ° C and manganese is 1244 ° C.

  Metal formed by reducing the metal atom of the first metal group, the metal atom of the second metal group, and the copper salt of an aliphatic monocarboxylic acid, which is generated by reducing the metal carboxylate or metal carboxylate complex Aggregates composed of copper atoms cause alloying at a temperature exceeding the melting point of the metal of the first metal group. The metals of the first metal group are all low melting point metals, and the metal of the first metal group melts to promote alloying of the aggregates.

  In general, the alloying process becomes difficult as the content of the refractory metal increases.

  The metals of the second metal group have a melting point of 400 ° C. or higher except for indium. When alloying from an aggregate composed of metal atoms of the first metal group, metal atoms of the second metal group, and copper nanoparticles, the total number of metal atoms of the cation species of the second metal group is By keeping the total number of metal atoms of the cation species of the first metal group within less than 10%, it is guaranteed that alloying proceeds in the range of 300 ° C to 400 ° C.

  By reducing the carboxylic acid metal salt or metal carboxylic acid complex, the resistivity of the metal of the first metal group produced is 120 μΩ · cm (20 ° C.) for bismuth and 11 μΩ · cm (20 ° C.) for tin. The resistivity of metallic copper is an order of magnitude higher than that of 1.673 μΩ · cm (30 ° C.). Moreover, the resistivity of the metal of the 2nd metal group to produce | generate is 5.8 microhm * cm (20 degreeC) for zinc, 2.655 microohm * cm (20 degreeC) for aluminum, and 8.37 microohm * cm (20 degreeC) for indium. Silver is 1.59 μΩ · cm (20 ° C.), cobalt is 6.24 μΩ · cm (20 ° C.), titanium is 42.0 μΩ · cm (20 ° C.), nickel is 6.84 μΩ · cm (20 ° C.), manganese Is 185 μΩ · cm (20 ° C.). Except for silver, the resistivity of the metal of the second metal group is also higher than the resistivity of metal copper 1.673 μΩ · cm (30 ° C.).

  Accordingly, the alloy of the metal of the first metal group, the metal of the metal of the second metal group and copper increases in resistivity as the content ratio of the metal of the first metal group increases. Further, even in a range where the metal content ratio of the first metal group is low, the resistivity of the alloy of the metal of the first metal group, the metal of the second metal group and copper due to the influence of so-called alloy scattering, The resistivity is much higher than that of metallic copper.

  Metal formed by reducing the metal atom of the first metal group, the metal atom of the second metal group, and the copper salt of an aliphatic monocarboxylic acid, which is generated by reducing the metal carboxylate or metal carboxylate complex The alloy formed from the aggregate of copper atoms fills a narrow gap around the contact area between the fine copper powder and the copper powder, so that the content ratio of the metal of the first metal group and the metal of the second metal group is As it increases, the contact area at the contact site between the fine copper powder and the copper powder is increased. On the other hand, as the metal content ratio of the first metal group increases, the resistivity of the formed alloy itself rapidly increases from the resistivity of metallic copper. The effect of this “increase in resistivity caused by alloying” becomes more prominent as the resistivity of the metal of the first metal group is higher.

  Therefore, when the metal content ratio of the first metal group exceeds a certain level, the effect of “expansion of contact area” is offset by the effect of “increased resistivity caused by alloying”.

In other words, the total volume V _low-mp-metal of the metal atoms of the first metal group which is a low melting point metal produced by reducing the carboxylic acid metal salt or metal carboxylic acid complex, and an aliphatic monocarboxylic acid The total volume of copper atoms generated by the reduction of the copper salt V _Cu-metal ratio, V _low-mp-metal : V _Cu-metal , depending on the type of metal in the first metal group (low melting point metal) Therefore, it is necessary to select a range that does not exceed a certain level. Typically, the ratio, V _low-mp-metal : V _Cu-metal, is selected at least in a range not exceeding 4: 1, usually not exceeding 2: 1, preferably not exceeding 1: 1. It is desirable to do.

In the conductive copper paste according to the first aspect of the present invention, the cation species of the first metal group and the cation species of the second metal group contained in the carboxylic acid metal salt or metal carboxylic acid complex are mixed. The total number of metal atoms of the mixed metal cation species is 100 μmol / m ² or less, preferably 80 μmol / m ² or less, based on the sum of the surface area of the copper powder and the surface area of the fine copper powder. more preferably, 50 [mu] mol / m ² or less of the range, particularly preferably, it is desirable to select the range of 30 [mu] mol / m ² or less.

  In addition, in the conductive copper paste according to the second embodiment of the present invention, in addition to the copper nanoparticles, the conductive copper paste further includes a copper salt of an aliphatic monocarboxylic acid and the following sintering aid. It is also possible.

  That is, the copper salt of the aliphatic monocarboxylic acid used in the first aspect of the present invention and an organic solvent having an alcoholic hydroxyl group as a third organic solvent as a sintering aid, for example, the fourth In the presence of an aliphatic polyhydric alcohol as an organic solvent, a metal carboxylic acid salt or a metal cation species other than copper and a carboxylic acid anion species, which can generate a metal atom when reduced by performing light irradiation described later, A metal carboxylic acid complex can be further added.

In one embodiment of the conductive copper paste, in addition to the copper salt of the aliphatic monocarboxylic acid, further adding the sintering aid,
In the carboxylic acid metal salt or metal carboxylic acid complex, which is added as a sintering aid and becomes a metal cation species other than copper and a carboxylic acid anion species,
The metal cation species other than copper is selected from the group consisting of bismuth and tin, or one or a plurality of types of metal cation species,
The carboxylic acid anion species is an anionic species of carboxylic acid selected from the group consisting of aliphatic monocarboxylic acids having 6 to 20 carbon atoms.

  By reducing the carboxylic acid metal salt or metal carboxylic acid complex, the metal atom produced is a fine copper atom together with the metal copper atom produced by reducing the copper salt of the aliphatic monocarboxylic acid, and the copper nanoparticles. Narrow gaps around the contact area between the powder and copper powder, and narrow gaps around the contact area between the resin base material and the fine copper powder and copper powder are filled.

  By reducing the carboxylic acid metal salt or metal carboxylic acid complex, the melting point of the metal produced is 271.4 ° C. for bismuth and 232 ° C. for tin, and at least a temperature of 350 ° C. or higher is in a molten state. . Aggregates composed of these low-melting-point metal atoms generated by reducing the carboxylic acid metal salt or metal carboxylic acid complex, and metal copper atoms generated by reducing the copper salt of an aliphatic monocarboxylic acid Causes alloying at temperatures above the melting point of the low melting point metal. Along with the agglomerates of the low-melting-point metal atoms and metal copper atoms and the copper nanoparticles, the fine copper powder, the narrow gap around the contact area of the copper powder, the contact between the resin substrate and the fine copper powder, the copper powder It fills a narrow gap around the site.

  By reducing the metal carboxylate or metal carboxylate complex, the resistivity of the metal produced is 120 μΩ · cm (20 ° C.) for bismuth and 11 μΩ · cm (20 ° C.) for tin, and the resistance of metal copper Compared with the rate of 1.673 μΩ · cm (30 ° C.), it is an order of magnitude higher value. Therefore, in the alloy composed of these low melting point metal atoms and metallic copper atoms, the resistivity rapidly increases as the content ratio of the low melting point metal increases. Even in a range where the content ratio of the low melting point metal is low, the resistivity of the alloy composed of the low melting point metal and copper is much higher than the resistivity of metallic copper due to the so-called alloy scattering.

  From an aggregate composed of these low melting point metal atoms generated by reducing the metal carboxylate or metal carboxylate complex and metal copper atoms generated by reducing the copper salt of an aliphatic monocarboxylic acid The formed alloy fills a narrow gap around the contact area between the fine copper powder and the copper powder, so the content ratio of the low melting point metal increases and the contact area at the contact area between the fine copper powder and the copper powder increases. Enlargement is made. On the other hand, as the content ratio of the low melting point metal increases, the resistivity of the formed alloy itself increases rapidly from the resistivity of metallic copper. The effect of the “increase in resistivity caused by alloying” becomes more prominent as the resistivity of the low melting point metal is higher.

  Accordingly, when the content ratio of the low melting point metal exceeds a certain level, the effect of “expansion of contact area” is offset by the effect of “increase in resistivity caused by alloying”.

In other words, the metal produced by the reduction of the total volume V _{low-mp-metal of} low melting point metal atoms and the copper salt of an aliphatic monocarboxylic acid produced by reducing the carboxylic acid metal salt or metal carboxylic acid complex. The ratio of the total volume of copper atoms V _Cu-metal , V _low-mp-metal : V _Cu-metal needs to be selected in a range not exceeding a certain level according to the type of low melting point metal. Usually, the ratio, V _low-mp-metal : V _Cu-metal is selected in a range not exceeding 4: 1, preferably not exceeding 2: 1, more preferably not exceeding 1: 1. It is desirable to do.

In the conductive copper paste according to the second aspect of the present invention, the total number of metal atoms of the metal cation species contained in the carboxylic acid metal salt or metal carboxylic acid complex is the surface area of the copper powder and the fine copper powder. against the sum of the surface area, 100 [mu] mol / m ² or less, preferably in the range of from, 80μmol / m ² or less, more preferably in the range, 50 [mu] mol / m ² or less of the range, particularly preferably, 30 [mu] mol / m ² or less of It is desirable to select a range.

In addition, in another aspect of the conductive copper paste in which the copper salt of an aliphatic monocarboxylic acid and the sintering aid are further added,
In the carboxylic acid metal salt or metal carboxylic acid complex, which is added as the sintering aid and becomes a metal cation species other than copper and a carboxylic acid anion species,
The metal cation species other than copper is a mixed metal cation species formed by mixing a cation species of the first metal group and a cation species of the second metal group,
The cation species of the first metal group is selected from the group consisting of bismuth and tin, or one or more metal cation species,
The cation species of the second metal group is selected from the group consisting of zinc, aluminum, indium, silver, cobalt, titanium, nickel, manganese, or a cation species of one or more metals.
In the mixed metal cation species, the total number of metal atoms of the cation species of the second metal group is selected within a range of less than 10% with respect to the total number of metal atoms of the cation species of the first metal group. And
The carboxylic acid anion species is an anionic species of carboxylic acid selected from the group consisting of aliphatic monocarboxylic acids having 6 to 20 carbon atoms.

  By reducing the carboxylic acid metal salt or metal carboxylic acid complex, the metal atom of the first metal group and the metal atom of the second metal group are produced by reduction of a copper salt of an aliphatic monocarboxylic acid. Along with copper atoms and copper nanoparticles, the fine copper powder, a narrow gap around the contact area between the copper powders, and a narrow gap around the contact area between the resin substrate and the fine copper powder, the copper powder are filled.

  By reducing the metal carboxylate or metal carboxylate complex, the melting point of the metal of the first metal group produced is 271.4 ° C. for bismuth and 232 ° C. for tin, and at least at a temperature of 350 ° C. or higher. It will be in a molten state. In addition, the melting point of the metal of the second metal group to be generated is 419.5 ° C. for zinc, 660.36 ° C. for aluminum, 156.6 ° C. for indium, 961 ° C. for silver, 1495 ° C. for cobalt, 1667 ° C. for titanium, Nickel is 1456 ° C and manganese is 1244 ° C.

  The aggregate composed of the metal atom of the first metal group, the metal atom of the second metal group, and the copper nanoparticles produced by reducing the metal carboxylate or metal carboxylate complex, Alloying occurs at temperatures above the melting point of a single metal group. The metals of the first metal group are all low melting point metals, and the metal of the first metal group melts to promote alloying of the aggregates.

  In general, the alloying process becomes difficult as the content of the refractory metal increases.

  The metals of the second metal group have a melting point of 400 ° C. or higher except for indium. When alloying from an aggregate composed of a metal atom of the first metal group, a metal atom of the second metal group, and a metal copper atom formed by reduction of a copper salt of an aliphatic monocarboxylic acid, By keeping the sum of the number of metal atoms of the cation species of the metal group within a range of less than 10% with respect to the sum of the number of metal atoms of the cation species of the first metal group, It is guaranteed that alloying will proceed.

  By reducing the carboxylic acid metal salt or metal carboxylic acid complex, the resistivity of the metal of the first metal group produced is 120 μΩ · cm (20 ° C.) for bismuth and 11 μΩ · cm (20 ° C.) for tin. Compared with the resistivity of metallic copper, 1.673 μΩ · cm (30 ° C.), it is an order of magnitude higher value. Moreover, the resistivity of the metal of the 2nd metal group to produce | generate is 5.8 microhm * cm (20 degreeC) for zinc, 2.655 microohm * cm (20 degreeC) for aluminum, and 8.37 microohm * cm (20 degreeC) for indium. Silver is 1.59 μΩ · cm (20 ° C.), cobalt is 6.24 μΩ · cm (20 ° C.), titanium is 42.0 μΩ · cm (20 ° C.), nickel is 6.84 μΩ · cm (20 ° C.), manganese Is 185 μΩ · cm (20 ° C.). Except for silver, the resistivity of the metal of the second metal group is also higher than the resistivity of metallic copper, 1.673 μΩ · cm (30 ° C.).

  Therefore, the alloy of the metal of the first metal group, the metal of the second metal group and copper has a resistivity rapidly as the content ratio of the metal of the first metal group and the metal of the second metal group increases. To rise. In addition, even in a range where the content ratio of the metal of the first metal group and the metal of the second metal group is low, the so-called alloy scattering affects the metal of the first metal group, the metal of the second metal group, and copper. The resistivity of the resulting alloy is much higher than that of metallic copper.

  Metal formed by reducing the metal atom of the first metal group, the metal atom of the second metal group, and the copper salt of an aliphatic monocarboxylic acid, which is generated by reducing the metal carboxylate or metal carboxylate complex The alloy formed from the aggregate composed of copper atoms fills a narrow gap around the contact area between the fine copper powder and the copper powder, so that the metal of the first metal group and the metal of the second metal group As the content ratio increases, the contact area at the contact portion between the fine copper powder and the copper powder is increased. On the other hand, as the content ratio of the metal of the first metal group and the metal of the second metal group increases, the resistivity of the formed alloy itself increases rapidly from the resistivity of metallic copper. The effect of the “increase in resistivity caused by alloying” becomes more prominent as the resistivity of the metal of the first metal group and the metal of the second metal group is higher.

  Therefore, when the content ratio of the metal of the first metal group and the metal of the second metal group exceeds a certain level, the effect of “expansion of contact area” is influenced by the effect of “increase in resistivity due to alloying”. cancel.

In other words, the total volume V _low-mp-metal of the metal atoms of the first metal group, which is a low melting point metal, which is generated by reducing the carboxylic acid metal salt or metal carboxylic acid complex, and the second metal group The ratio of the total volume V of the metal atoms V _{second-metal to} the total volume V _Cu-metal of the copper metal atoms generated by the reduction of the copper salt of the aliphatic monocarboxylic acid, (V _low-mp-metal + V _second-metal ): V _Cu-metal needs to be selected in a range not exceeding a certain level according to the type of metal (low melting point metal) of the first metal group and the type of metal of the second metal group.

The sum of the number of metal atoms of the cation species of the second metal group is kept within a range of less than 10% with respect to the sum of the number of metal atoms of the cation species of the first metal group. V _low-mp-metal + V _second-metal ): In place of the conditions for V _Cu-metal , the total volume V _{low-mp-metal of} the first metal group which is a low melting point _metal and an aliphatic monocarboxylic Volume ratio of copper metal atoms generated by reduction of copper salt of acid V _Cu-metal ratio, V _low-mp-metal : V _Cu-metal is the first metal group metal (low melting point metal) Accordingly, it is possible to adopt a condition of selecting a range that does not exceed a certain level. Usually, the ratio, V _low-mp-metal : V _Cu-metal is selected in a range not exceeding 4: 1, preferably not exceeding 2: 1, more preferably not exceeding 1: 1. It is desirable to do. Therefore, (V _low-mp-metal + V _second-metal ): V _Cu-metal also does not exceed 4: 1, preferably does not exceed 2: 1, more preferably does not exceed 1: 1. It is desirable to select a range.

In the conductive copper paste according to the second aspect of the present invention, the cation species of the first metal group and the cation species of the second metal group contained in the carboxylic acid metal salt or metal carboxylic acid complex are mixed. The total number of metal atoms of the mixed metal cation species is 100 μmol / m ² or less, preferably 80 μmol / m ² or less, based on the sum of the surface area of the copper powder and the surface area of the fine copper powder. more preferably, 50 [mu] mol / m ² or less of the range, particularly preferably, it is desirable to select the range of 30 [mu] mol / m ² or less.

  In addition, in any of the conductive copper paste according to the first aspect of the present invention and the conductive copper paste according to the second aspect of the present invention, a metal cation species other than copper, which is added as the sintering aid, The carboxylic acid metal salt or metal carboxylic acid complex, which becomes the carboxylic acid anion species, is used as the first organic solvent or the third organic solvent, and is an organic solvent having the above-mentioned alcoholic hydroxyl group, for example, an aliphatic polyvalent group. In a monohydric alcohol, it is dissolved in the form of an amine complex of the carboxylic acid metal salt or metal carboxylic acid complex.

Specifically, (dialkylamino) alkylamine (R ′ ₂ N—C _m H _2m —NH ₂ ) is contained in the liquid phase of the conductive copper paste. Carboxylic acid metal salts or metal carboxylic acid complexes, such as divalent metal cation species (M ²⁺ ) and carboxylic acid anions (R ″ -COO ⁻ ), which become metal cation species other than copper and carboxylate anion species Coordination of (dialkylamino) alkylamine as a monodentate ligand to the metal cation species (M ²⁺ ) in (R ″ —COO ⁻ ) ₂ (M ²⁺ ) comprising ((R "-COO) ₂ M (II)): 2 (R ' ₂ NC _m H _2m -NH ₂ )) is thus formed, which becomes a metal cation species other than copper and a carboxylate anion species. The carboxylic acid metal salt or metal carboxylic acid complex is an amine complex, for example, in the form of ((R "-COO) ₂ M (II)): 2 (R ' ₂ NC _m H _2m -NH ₂ )) Used as a third organic solvent, an organic solvent having an alcoholic hydroxyl group, such as an aliphatic polyhydric alcohol. It is.

An amine complex of a carboxylic acid metal salt or metal carboxylic acid complex, which becomes a metal cation species other than copper and a carboxylic acid anion species, for example, ((R "-COO) ₂ M (II)): 2 (R ' ₂ NC _m H _2m —NH ₂ )) is an amine complex of an aliphatic monocarboxylic acid copper salt ((R—COO) ₂ Cu (II)): 2 (R ′ ₂ NC _m H _2m It is reduced by the same reaction mechanism as that for —NH ₂ )).

Also, amine complexes of carboxylic acid metal salts or metal carboxylic acid complexes, for example, amine complexes in the form of ((R "-COO) ₂ M (II)): 2 (R ' ₂ NC _m H _2m -NH ₂ )) The metal atom M (0) produced by the reduction of is initially in the form of coordination of two molecules of (dialkylamino) alkylamine.When (dialkylamino) alkylamine functions as a bidentate ligand, , Disperse in a dispersion solvent as a metal atom (M (0): 2 (R ′ ₂ NC _m H _2m —NH ₂ )) coordinated by two (dialkylamino) alkylamine molecules of the bidentate ligand be able to.

Carboxylic acid derived from carboxylate anion (R ″ -COO ⁻ ) (R ″ -COO ⁻ ) with reduction of carboxylate metal salt or amine complex of metal carboxylate complex which becomes metal cation species other than copper and carboxylate anion species -COOH) is by-produced.

  The carboxylic acid anion species is an anionic species of carboxylic acid selected from the group consisting of aliphatic monocarboxylic acids having 6 to 20 carbon atoms (R ″ —COOH).

In this case, a carboxylic acid metal salt that becomes a carboxylic acid anion (R ″ —COO ⁻ ) derived from the aliphatic monocarboxylic acid (R ″ —COOH) having 6 to 20 carbon atoms and a metal cation species other than copper, or When the metal carboxylic acid complex is used as the first organic solvent and the third organic solvent, the organic solvent having an alcoholic hydroxyl group, such as an aliphatic polyhydric alcohol, is irradiated with light as described later. It is desirable that the reduction reaction using the above-mentioned organic solvent having an alcoholic hydroxyl group, for example, an aliphatic polyhydric alcohol, proceeds preferentially over the decomposing reduction reaction. In general, the autolytic decomposition reaction of a metal salt of an aliphatic monocarboxylic acid ((R ″ —COO) ₂ M (II)) increases the carbon number of the aliphatic monocarboxylic acid anion, and the reaction initiation temperature is Therefore, in the conductive copper paste according to the first aspect of the present invention, the aliphatic monocarboxylic acid anion constituting the metal salt of aliphatic monocarboxylic acid ((R ″ —COO) ₂ M (II)). It is desirable to select an anion derived from an aliphatic monocarboxylic acid having 6 to 20 carbon atoms.

On the other hand, in the mechanism described above, an aliphatic monocarboxylic acid (R ″ —COOH) is by-produced as the carboxylic acid metal salt or amine complex of the metal carboxylic acid complex is reduced. Desirably, the aliphatic monocarboxylic acid (R ″ —COOH) is evaporated. Accordingly, the boiling point of the aliphatic monocarboxylic acid (R ″ —COOH) is 230 ° C. or higher, but does not exceed 400 ° C., preferably 230 ° C. or higher, but does not exceed 300 ° C. Accordingly, an aliphatic monocarboxylic acid (R ″ −) having a boiling point of 230 ° C. or higher but not exceeding 400 ° C., preferably 230 ° C. or higher but not exceeding 300 ° C. It is desirable to employ a metal salt of an aliphatic monocarboxylic acid ((R ″ —COO) ₂ M (II)) derived from (COOH).

  In addition, the linear alkanoic acid in the range of C7 heptanoic acid (boiling point 223.0 ° C) to C12 lauric acid (dodecanoic acid, boiling point 298.9 ° C) does not exceed 300 ° C. It can be used as an aliphatic monocarboxylic acid.

Using the conductive copper paste according to the present invention, when a conductive film such as a copper wiring layer or an electrode layer is formed on a resin base material, a coating film of the conductive copper paste is formed in a desired coating shape. To do. The film thickness t _drawing of the conductive copper paste coating film is selected according to the thickness t _layer of the conductive film to be produced.

When the conductive copper paste according to the first aspect of the present invention is used, the ratio of the thickness t _{layer of the} conductive film to be produced and the film thickness t _drawing of the coating film, t _layer / t _drawing is the conductivity. Depends on the total volume ratio of the copper powder and fine copper powder contained in the copper paste.

  The total volume ratio of the copper powder and fine copper powder contained in the conductive copper paste according to the first embodiment of the present invention is in the range of 30% by volume to 60% by volume, preferably 40% by volume to It is desirable to be selected in the range of 55% by volume.

  Further, when forming the coating film of the conductive copper paste in a desired coating shape, for example, when a screen printing method is applied, the liquid viscosity of the conductive copper paste needs to be a viscosity suitable for the screen printing method. There is. When the screen printing method is applied, the liquid viscosity of the conductive copper paste is in the range of 2 Pa · s to 50 Pa · s (25 ° C.), more preferably in the range of 2 Pa · s to 40 Pa · s (25 ° C.). Preferably it is selected.

When the conductive copper paste according to the second aspect of the present invention is used, the ratio of the thickness t _{layer of the} conductive film to be produced and the film thickness t _drawing of the coating film, t _layer / t _drawing It depends on the total volume ratio of the copper powder, fine copper powder, and copper nanoparticles contained in the copper paste.

  The total of the volume ratio of the copper powder, fine copper powder, and copper nanoparticles contained in the conductive copper paste according to the second embodiment of the present invention is in the range of 30% by volume to 70% by volume, preferably It is desirable that it is selected in the range of 30% to 55% by volume, more preferably in the range of 40% to 55% by volume.

  Further, when forming the coating film of the conductive copper paste in a desired coating shape, for example, when a screen printing method is applied, the liquid viscosity of the conductive copper paste needs to be a viscosity suitable for the screen printing method. There is. When the screen printing method is applied, the liquid viscosity of the conductive copper paste is in the range of 2 Pa · s to 50 Pa · s (25 ° C.), more preferably in the range of 2 Pa · s to 40 Pa · s (25 ° C.). Preferably it is selected.

When a conductive film is produced on a resin substrate using the conductive copper paste according to the first aspect of the present invention, the adhesion of the conductive film to the surface of the resin substrate is improved by an aliphatic monolithic material. The effective contact area between the resin substrate and the sintered body layer is expanded by utilizing metal copper atoms generated by reduction of the carboxylic acid copper salt ((R—COO) ₂ Cu (II)). Has been achieved.

  When the conductive copper paste according to the second embodiment of the present invention is used to produce a conductive film on a resin base material, the adhesion of the conductive film to the surface of the resin base material is improved by copper nanoparticles. This is achieved by expanding the effective contact area between the resin base material and the sintered body layer by utilizing the metal copper film formed from the above.

  Therefore, the conductive copper paste according to the present invention does not contain a thermosetting resin component or glass frit.

On the other hand, the conductive copper paste according to the present invention contains a polymer binder having a thermal decomposition temperature of 200 to 500 ° C.
Here, the pyrolysis temperature refers to a temperature when the mass of the polymer binder is reduced by 98% using a calorimeter measuring device (TGA), and is preferably 200 to 400 ° C.
Specific examples of the polymer binder include epoxy resin, acrylic resin, polyvinyl alcohol, polyvinyl butyral, polyvinyl pyrrolidone, polyethylene glycol, polyethyleneimine, a reaction product of a silane coupling agent, water-soluble polyamide, gelatin, A cellulose derivative etc. are mentioned, These may be used individually by 1 type and may use 2 or more types together.
Among these, it is preferable to use polyvinylpyrrolidone because the reduction easily proceeds by light irradiation described later.

In the conductive copper paste according to the first aspect of the present invention, ablation during film formation is further suppressed, the film quality of the produced conductive film is improved, and the remaining of organic substances, which is a conductivity inhibiting factor, is also present. For the reason of being suppressed, the ratio (copper / polymer binder) of the mass of the copper component, the total of the copper powder, the fine copper powder and the copper salt of the aliphatic monocarboxylic acid and the mass of the polymer binder is 70. It is preferably / 30 to 98/2.
For the same reason, in the conductive copper paste according to the second embodiment of the present invention, the ratio of the mass of the copper component, which is the sum of the fine copper powder and the copper nanoparticles, to the mass of the polymer binder (copper / The polymer binder) is preferably 70/30 to 98/2.

In addition to the essential components described above, the conductive copper paste according to the present invention is reduced by light irradiation, which will be described later, to obtain metallic copper, for the reason that the conductivity of the produced conductive film becomes higher. Furthermore, it is preferable to contain copper oxide.
Here, copper oxide is a compound that does not substantially contain copper that has not been oxidized. Specifically, in a crystal analysis by X-ray diffraction, a peak derived from copper oxide is detected, and a peak derived from metal Refers to a compound in which is not detected. Although not containing copper substantially, it means that content of copper is 1 mass% or less with respect to copper oxide particles.
As the copper oxide, copper (I) oxide or copper (II) oxide is preferable, and copper (II) oxide is more preferable because it is available at low cost.

Furthermore, in addition to the essential components described above, the conductive copper paste according to the present invention further contains silver nanoparticles for the reason that the denseness of the conductive film to be produced is improved and the conductivity is higher. Is preferred.
Here, a silver nanoparticle will not be specifically limited if it is a silver particle with an average particle diameter of 10 nm-100 nm.

  In the method for producing a conductive film of the present invention, after the above-described conductive copper paste according to the present invention is applied on a resin substrate, the residual amount of the organic solvent (first to fourth organic solvents) is 0.1. It is characterized in that the film is irradiated with light in a state of ˜5 mass%.

<Resin substrate>
The resin substrate is not particularly limited, and specific examples of the resin that is a constituent material thereof include, for example, a low density polyethylene resin, a high density polyethylene resin, an ABS resin, a polyimide resin, an acrylic resin, a styrene resin, and vinyl chloride. Examples thereof include resins, polyester resins (polyethylene terephthalate), polyacetal resins, polysulfone resins, polyetherimide resins, polyether ketone resins, and cellulose derivatives.
In addition, the resin base material has a glass transition temperature (Tg) because of the influence of heat during film formation (sintering) and the suppression of deformation due to shrinkage of the conductive copper paste applied on the resin base material. Preferably it is 50-400 degreeC, It is more preferable that it is 50-200 degreeC, It is still more preferable that it is 65-180 degreeC, Specifically, the polyimide resin mentioned above, an acrylic resin, a styrene resin, a polyester resin are mentioned. (Polyethylene terephthalate) is preferred.

<Application method>
The method for applying the conductive copper paste on the resin substrate is not particularly limited. For example, screen printing, dip coating, spray coating, spin coating, ink jet, gravure offset printing, flexographic printing, etc. An application method is mentioned.
Among these, the screen printing method, the gravure offset printing method, and the flexographic printing method are preferable because it is easy to adjust the remaining amount of the organic solvent to a range described later.
Moreover, the shape of application | coating is not restrict | limited in particular, It may be the surface shape which covers the whole resin base material, or pattern shape (for example, wiring shape, dot shape).
The coating amount of the conductive copper paste on the resin substrate may be adjusted as appropriate according to the desired thickness of the conductive film, but usually the coating thickness is preferably 0.01 to 5000 μm. 0.1 to 1000 μm is more preferable.

<Remaining amount of organic solvent>
In the manufacturing method of the electrically conductive film of this invention, when irradiating with light, it is necessary to make the residual amount of the organic solvent in the electroconductive copper paste apply | coated on the resin base material 0.1-5 mass%.
Here, the remaining amount of the organic solvent can be adjusted by means such as drying (including natural drying) after applying the conductive copper paste onto the resin substrate.
Generation | occurrence | production of ablation can be suppressed at the time of the film-forming of the electroconductive copper paste by light irradiation as the residual amount of an organic solvent is the range mentioned above. This is presumably because the evaporation of the organic solvent remaining in the conductive copper paste due to rapid heating and temperature rise caused by the photo sintering was suppressed.
Moreover, from the reason which can suppress generation | occurrence | production of ablation more, it is preferable that the residual amount of an organic solvent is 0.1-3 mass%, and it is more preferable that it is 0.1-2 mass%.

<Light irradiation>
The light source used for light irradiation is not particularly limited, and examples thereof include a mercury lamp, a metal halide lamp, a xenon lamp, a chemical lamp, and a carbon arc lamp. Examples of radiation include electron beams, X-rays, ion beams, and far infrared rays. Further, g-line, i-line, deep-UV light, and high-density energy beam (laser beam) are also used.
Specific examples of preferred embodiments include scanning exposure with an infrared laser, high-illuminance flash exposure such as a xenon discharge lamp, and infrared lamp exposure.

Such light irradiation is preferably light irradiation with a flash lamp, and more preferably pulsed light irradiation with a flash lamp. Irradiation with high-energy pulsed light can concentrate and heat the surface of the portion to which the coating film has been applied in a very short time, so that the influence of heat on the substrate can be extremely reduced.
The irradiation energy of the pulse light is preferably 1~100J / cm ^2, more preferably 1~30J / cm ^2, preferably 1μ seconds ~100m sec as a pulse width, and more preferably 10μ sec ~10m seconds. The irradiation time of the pulsed light is preferably 1 to 100 milliseconds, more preferably 1 to 50 milliseconds, and further preferably 1 to 20 milliseconds.

A conductive film is obtained by performing the light irradiation described above.
The film thickness of the conductive film is not particularly limited, and an optimum film thickness is appropriately adjusted according to the intended use. Especially, from the point of a printed wiring board use, 0.01-1000 micrometers is preferable and 0.1-100 micrometers is more preferable.
The film thickness is a value (average value) obtained by measuring three or more thicknesses at arbitrary points on the conductive film and arithmetically averaging the values.
The volume resistance value of the conductive film is preferably less than 100 μΩ · cm, and more preferably less than 50 μΩ · cm, from the viewpoint of conductive characteristics.
The volume resistance value can be calculated by multiplying the obtained surface resistance value by the film thickness after measuring the surface resistance value of the conductive film by the four-probe method.

The conductive film may be provided on the entire surface of the base material or in a pattern. The patterned conductive film is useful as a conductor wiring (wiring) such as a printed wiring board.
As a method for obtaining a patterned conductive film, the conductive copper paste is applied to a resin base material in a pattern and irradiated with light, or the conductive film provided on the entire surface of the resin base material is etched into a pattern. The method etc. are mentioned.
The etching method is not particularly limited, and a known subtractive method, semi-additive method, or the like can be employed.

  When a patterned conductive film is configured as a multilayer wiring board, an insulating layer (insulating resin layer, interlayer insulating film, solder resist) is further laminated on the surface of the patterned conductive film, and further wiring (metal) is formed on the surface. Pattern) may be formed.

The material of the insulating layer is not particularly limited. For example, epoxy resin, glass epoxy resin, aramid resin, crystalline polyolefin resin, amorphous polyolefin resin, fluorine-containing resin (polytetrafluoroethylene, perfluorinated polyimide, perfluorinated) Amorphous resin), polyimide resin, polyether sulfone resin, polyphenylene sulfide resin, polyether ether ketone resin, liquid crystal resin, and the like.
Among these, from the viewpoints of adhesion, dimensional stability, heat resistance, electrical insulation, and the like, it is preferable to contain an epoxy resin, a polyimide resin, or a liquid crystal resin, and more preferably an epoxy resin. Specifically, ABF TECH-13, ABF GX-13, etc. are mentioned.

  Further, a solder resist, which is a kind of insulating layer material used for wiring protection, is described in detail in, for example, JP-A-10-204150, JP-A-2003-222993, and the like. These materials can also be applied to the present invention if desired. A commercially available solder resist may be used, and specific examples include PFR800 manufactured by Taiyo Ink Manufacturing Co., Ltd., PSR4000 (trade name), SR7200G manufactured by Hitachi Chemical Co., Ltd., and the like.

  The resin base material which has the electrically conductive film obtained above can be used for various uses. For example, a printed wiring board, TFT, FPC, RFID, etc. are mentioned.

  Hereinafter, the present invention will be described more specifically with reference to examples. These examples are examples of the best mode according to the present invention, but the present invention is not limited by these examples.

Example 1
The conductive copper paste of Example 1 is prepared using the following raw materials.

As the average particle size is selected in the range of 2 to 10 μm, Mitsui Metals' spherical copper powder MA-C08JM (average particle size of 7 μm) is used, and the average particle size is selected in the range of 0.2 μm to 1.0 μm. Mitsui Metals fine copper powder 1020Y (average particle size 0.4 μm) was used as the fine copper powder, and polyvinylpyrrolidone (K60, MW: 150,000, thermal decomposition temperature: 400 ° C., manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the polymer binder. . The ratio of the average particle diameter d _{Cu-fine-powder of the fine} copper powder and the average particle diameter d _Cu-powder of the spherical copper powder (d _{Cu-fine-powder} / d _Cu-powder ) is selected to _4/70 Has been.

As a copper salt of aliphatic monocarboxylic acid ((R—COO) ₂ Cu (II)), copper oleate ((CH ₃ (CH ₂ ) ₇ CH═CH (CH ₂ ) ₇ COO) ₂ Cu (II): Oleic acid having a molecular weight of 626.54) was previously dissolved in dibutylaminopropylamine ((C ₄ H ₉ ) ₂ N (CH ₂ ) ₃ NH ₂ , melting point: −50 ° C., boiling point: 238 ° C.) A copper amine complex is formed. The solid copper oleate itself forms a dimer having a Cu: Cu bond. The amine complex of copper oleate formed is composed of dibutylaminopropylamine (one molecule of copper oleate ((CH ₃ (CH ₂ ) ₇ CH═CH (CH ₂ ) ₇ COO) ₂ Cu (II))). It can be presumed that (C ₄ H ₉ ) ₂ N (CH ₂ ) ₃ NH ₂ ) 2 molecules coordinate to the copper cation (Cu ²⁺ ). As a result, the dimer type copper oleate is converted into an amine complex of two molecules of copper oleate and is dissolved in the solvent dibutylaminopropylamine. In Example 1, 3.3 parts by mass of copper oleate is dissolved in 6.6 parts by mass of dibutylaminopropylamine, and an amine solution of an amine complex of copper oleate is prepared in advance. The composition of the amine solution of the copper oleate amine complex is selected to be 7 molecules of dibutylaminopropylamine per molecule of copper oleate.

  The aliphatic polyhydric alcohol used as the first organic solvent is 2-ethyl-1,3-hexanediol (molecular weight: 146.2, melting point: −40 ° C., boiling point: 245 ° C.).

  70 parts by mass of Mitsui Metals spherical copper powder MA-C08JM (average particle size 7 μm) and 30 parts by mass of Mitsui Metals fine copper powder 1020Y (average particle size 0.4 μm), 3.3 parts by mass of copper oleate are added to dibutylamino A solution dissolved in 6.6 parts by mass of propylamine, 3 parts by mass of 2-ethyl-1,3-hexanediol, and polyvinylpyrrolidone (K60, MW: 150,000, thermal decomposition temperature: 400 ° C., manufactured by Tokyo Chemical Industry Co., Ltd.) Mix 6 parts by weight. Thereafter, the mixture is stirred with a stirring deaerator to prepare a copper paste in which the copper powder and the fine copper powder are uniformly dispersed in the liquid phase.

  Sum of the number of metallic copper atoms in the spherical copper powder and fine copper powder and the ratio of the number of copper atoms in the copper oleate, (sum of the number of metallic copper atoms in the spherical copper powder and fine copper powder): (oleic acid The number of atoms with copper in the copper) is 100: 0.335. Further, 0.013 mol of 2-ethyl-1,3-hexanediol is contained per 1 mol of metallic copper of the spherical copper powder and fine copper powder.

When the density of metallic copper is 8.95 g / cm ³ (20 ° C.) and the density of 2-ethyl-1,3-hexanediol is 0.942 g / cm ³ (25 ° C.), the volume of the spherical copper powder and fine copper powder Of the total volume (V _Cu-powder + V _{Cu-fine-powder} ) and the volume of the first organic solvent 2-ethyl-1,3-hexanediol (V _{dispersion-medium} ), (V _Cu-powder + V _{Cu -fine-powder} ): V _{dispersion-medium} is calculated as 20: 5.7.

The density of oleic acid copper ^{0.95g / cm 3 (20 ℃)} , since the density 0.826 g / cm ³ of dibutylaminopropylamine (20 ° C.), the oleic acid copper amine complex of the amine solution 10g The volume can be estimated as 11.6 cm ³ .

  Therefore, the volume ratio of the spherical copper powder to the fine copper powder in the prepared copper paste is 23% by volume.

  Moreover, when all the copper in 3.3 mass parts copper oleate is reduce | restored to a metal copper atom, the sum total of the metal copper atom originating in a copper oleate will be 0.335 mass part. Accordingly, the total volume of metallic copper atoms, spherical copper powder and fine copper powder derived from copper oleate with respect to 100 parts by volume of the prepared copper paste is 23 parts by volume.

  The liquid viscosity of the prepared copper paste was 3 Pa · s (spiral rotational viscometer 10 rpm 25 ° C.).

The prepared copper paste was applied in a 5 mm × 20 mm pattern on a PET (film thickness: 100 μm, glass transition temperature: 67 ° C., manufactured by Fuji Film) substrate. The average thickness of the copper paste coating film was 58 μm. The copper paste coating film was heat-treated at 150 ° C. for 10 minutes in the atmosphere to make the residual amount of organic solvent (residual solvent amount) 3.1 mass%, and then irradiated with light by a xenon flash lamp (manufactured by XENON) ( (Exposure energy: 3 J / cm ² , ² msec.) Was performed to produce a sintered body (conductive film, average film thickness: 49 μm) on the PET substrate.

<Electrical conductivity evaluation>
The volume resistivity was measured with respect to the obtained electrically conductive film using the four-probe method resistivity meter. The results are shown in Table 1 below.
In addition, the volume resistivity in the following Table 1 is a value obtained by measuring the volume resistivity at any four locations of the conductive film and arithmetically averaging them.

<Adhesion evaluation>
The resulting conductive film is cut into 11 grids at 1 mm intervals to reach the ground surface in a grid pattern with a cutter, and an adhesive tape (cello tape compliant with JIS K5400) is pasted on the conductive film. The state of adhesion of the conductive film to the substrate after peeling was visually observed and evaluated according to the following criteria. The results are shown in Table 1 below. Practically, it is preferably C or more.
“A”: the peeled area of the conductive film is 0 to 20% of the whole “B”: the peeled area of the conductive film is more than 20% and 40% or less of the whole “C”: the peeled of the conductive film "D": The area where the conductive film is peeled off is more than 60% and 80% or less. "E": The area where the conductive film is peeled is 80% of the whole. More than%

(Example 2)
The conductive copper paste of Example 2 is prepared using the following raw materials.

Use Mitsui Metals' spherical copper powder MA-C08JM (average particle size 7 μm) as the copper powder selected in the range of 2 to 10 μm in average particle size, and select in the range of 0.2 to 1.0 μm in average particle size Mitsui Metals fine copper powder 1020Y (average particle size 0.4 μm) is used as the fine copper powder, and polyvinylpyrrolidone (K60, MW: 150,000, thermal decomposition temperature: 400 ° C., manufactured by Tokyo Chemical Industry Co., Ltd.) is used as the polymer binder. used. The ratio of the average particle diameter d _{Cu-fine-powder of the fine} copper powder and the average particle diameter d _Cu-powder of the spherical copper powder (d _{Cu-fine-powder} / d _Cu-powder ) is selected to be _4/70 Has been.

As a copper nanoparticle which selects an average particle diameter in the range of 10 nm-100 nm, a copper nanoparticle with an average particle diameter of 70 nm is used. The surface of the copper nanoparticles is in a state where a coating molecular layer made of dibutylaminopropylamine is formed. At that time, the metal copper atoms exposed on the surface of the copper nanoparticles, dibutyl aminopropyl amine, using a lone pair of the amino (-NH _2), and a coordinative bond Yes. Specifically, a dispersion obtained by dispersing copper nanoparticles having an average particle diameter of 70 nm having a coating molecular layer of dibutylaminopropylamine in ethanol is used. The composition of the ethanol dispersion of copper nanoparticles having an average particle diameter of 70 nm is a composition containing 0.15 parts by mass of dibutylaminopropylamine and 5 parts by mass of ethanol as a dispersion solvent per 5 parts by mass of copper nanoparticles having an average diameter of 70 nm. Is selected.

  The aliphatic polyhydric alcohol used as the third organic solvent is 2-ethyl-1,3-hexanediol (melting point: −40 ° C., boiling point: 245 ° C.).

  65 parts by mass of Mitsui Metals spherical copper powder MA-C08JM (average particle diameter 7 μm) and 35 parts by mass of Mitsui Metals fine copper powder 1020Y (average particle diameter 0.4 μm) have 5 parts by mass of copper nanoparticles having an average diameter of 70 nm. Dispersion dispersed in 5 parts by mass of ethanol, 5 parts by mass of 2-ethyl-1,3-hexanediol, and polyvinylpyrrolidone (K60, MW: 150,000, thermal decomposition temperature: 400 ° C., manufactured by Tokyo Chemical Industry Co., Ltd.) Mix 6 parts by weight. Next, ethanol in the mixed solution is removed by an evaporator. Thereafter, the mixture is stirred with a stirring deaerator to prepare a copper paste in which the copper nanoparticles and the copper powder and fine copper powder are uniformly dispersed in the liquid phase.

  The sum of the metallic copper weight of the spherical copper powder and the fine copper powder, the weight of the copper nanoparticles, (the sum of the metallic copper weight of the spherical copper powder and the fine copper powder): (the weight of the copper nanoparticles) is 100: 5. It has become. Moreover, 0.021 mol of 2-ethyl-1,3-hexanediol is contained per 1 mol of metallic copper of the spherical copper powder and fine copper powder.

When the density of metallic copper is 8.95 g / cm ³ (20 ° C.) and the density of 2-ethyl-1,3-hexanediol is 0.942 g / cm ³ (25 ° C.), the volume of the spherical copper powder and fine copper powder Of the total volume (V _Cu-powder + V _{Cu-fine-powder} ) and the volume of the third organic solvent 2-ethyl-1,3-hexanediol (V _{dispersion-medium} ), (V _Cu-powder + V _{Cu -fine-powder} ): V _{dispersion-medium} is calculated as 21: 9.5.

  Therefore, the ratio of the total volume of the spherical copper powder, fine copper powder, and copper nanoparticles in the prepared copper paste is 70% by volume.

  The liquid viscosity of the prepared copper paste was 20 Pa · s (spiral rotational viscometer 10 rpm 25 ° C.).

The prepared copper paste was applied onto a PET substrate in the same manner as in Example 1, and irradiated with light to produce a conductive film on the PET substrate.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below.

(Example 3)
Example 1 with the exception that 10 parts by mass of a bismuth (III) 2-ethylhexanoate (II) 2-ethylhexanoic acid solution (bismuth content: 25% by mass, manufactured by Wako Pure Chemical Industries, Ltd.) was used as a sintering aid. A conductive copper paste was prepared in the same manner.
The prepared copper paste was applied onto a PET substrate in the same manner as in Example 1, and irradiated with light to produce a conductive film on the PET substrate.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below.

Example 4
A conductive copper paste was prepared in the same manner as in Example 1 except that 0.23 parts by mass of tin (II) 2-ethylhexanoate was used as a sintering aid.
The prepared copper paste was applied onto a PET substrate in the same manner as in Example 1, and irradiated with light to produce a conductive film on the PET substrate.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below.

(Examples 5 to 10)
As a solvent, instead of 2-ethyl-1,3-hexanediol (molecular weight: 146.23, melting point: -40 ° C, boiling point: 245 ° C), an alcoholic solvent having a hydroxyl group shown in Table 1 below A conductive copper paste was prepared in the same manner as in Example 1 except that was used.
Each prepared copper paste was apply | coated on the PET base material by the method similar to Example 1, and light irradiation was performed, and the electrically conductive film was produced on the PET base material.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below.

(Examples 11-14)
A conductive copper paste was prepared in the same manner as in Example 1 except that the polymer binder shown in Table 1 below was used instead of the polymer binder (polyvinylpyrrolidone K60) used in Example 1.
Each prepared copper paste was apply | coated on the PET base material by the method similar to Example 1, and light irradiation was performed, and the electrically conductive film was produced on the PET base material.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below.

(Examples 15 to 17)
Example 1 except that the resin base material shown in Table 1 below was used instead of the PET base material used in Example 1 (film thickness: 100 μm, glass transition temperature: 67 ° C., manufactured by FUJIFILM Corporation). A conductive copper paste was prepared in the same manner.
Each prepared copper paste was apply | coated on the resin base material by the method similar to Example 1, light irradiation was performed, and the electrically conductive film was produced on the resin base material.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below.

(Examples 18 and 19)
Instead of the copper powder used in Example 1 (Mitsui Metals spherical copper powder 1400YM) and Mitsui Metals fine copper powder 1020Y), the examples except that the copper powder and fine copper powder shown in Table 1 below were used. 1 was used to prepare a conductive copper paste.
Each prepared copper paste was apply | coated on the PET base material by the method similar to Example 1, and light irradiation was performed, and the electrically conductive film was produced on the PET base material.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below.

(Example 20)
A conductive copper paste was prepared in the same manner as in Example 1.
Each prepared copper paste was applied onto a PET substrate in the same manner as in Example 1, and the coating film was heat-treated at 150 ° C. for 10 minutes in the air to determine the residual amount of organic solvent (residual solvent amount). After adjusting to 2.5% by mass, light irradiation with an infrared laser (CO ₂ / infrared, produced by Keyence Corporation) was performed to produce a conductive film on the PET substrate.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below.

(Examples 21 to 23)
In the same manner as in Example 1 except that the fusing agent shown in Table 1 below was used instead of the fusing agent (complex composed of copper oleate and dibutylaminopropylamine) used in Example 1. A conductive copper paste was prepared.
Each prepared copper paste was apply | coated on the PET base material by the method similar to Example 1, and light irradiation was performed, and the electrically conductive film was produced on the PET base material.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below.

(Comparative Example 1)
A conductive copper paste was prepared in the same manner as in Example 1 except that the polymer binder (polyvinylpyrrolidone K60) was not used, and a conductive film was produced on a PET substrate.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below. In addition, about the electroconductivity, since most of the electrically conductive films were lose | disappeared by ablation, it was not able to measure, and about the film thickness and adhesiveness, it evaluated with the electrically conductive film partly remained.

(Comparative Example 2)
Example 1 except that glycerin was used in place of the solvent (2-ethyl-1,3-hexanediol) used in Example 1 and the light irradiation was performed under the condition that the residual solvent amount exceeds 5% by mass. A conductive film was produced on a PET substrate by the same method as described above.
About the obtained electrically conductive film, the electroconductivity and adhesiveness were evaluated by the method similar to Example 1. FIG. These results are shown in Table 1 below. In addition, about the electroconductivity, since most of the electrically conductive films were lose | disappeared by ablation, it was not measurable, and about the film thickness and adhesiveness, it evaluated with the electrically conductive film which remain | survived in part.

From the results shown in Table 1, ablation occurs when conductive copper paste prepared without adding a polymer binder is used, or when light irradiation is performed with a large amount of organic solvent remaining in the coating film. (Comparative Examples 1 and 2).
In contrast, when a polymer binder is used and the content of the organic solvent remaining in the coating film is adjusted to a specific range and light irradiation is performed, ablation is suppressed, excellent conductivity, and adhesion to the substrate. It turned out that the electrically conductive film excellent also in the property can be obtained (Examples 1-23).
In particular, it was found that by using a conductive copper paste prepared by adding silver nanoparticles or copper oxide, the conductivity was higher and the adhesion with the substrate was further improved (Examples 21 to 23). ).

  The conductive copper paste according to the present invention can be used for forming a conductive film in which a conductive copper paste containing a conventional glass frit or a conductive copper paste containing a thermosetting resin component is used. Specifically, the conductive film formed using the conductive copper paste according to the present invention exhibits good conductive properties, for example, good adhesion to glass, silicon wafer, etc. It can be suitably used as a material for forming an electrode of a solar cell.

Claims (9)

A method for producing a conductive film using a conductive copper paste not containing a thermosetting resin component or glass frit,
The conductive copper paste is
Copper powder, fine copper powder, copper salt of aliphatic monocarboxylic acid, (dialkylamino) alkylamine, polymer binder, and first organic solvent,
The polymer binder has a thermal decomposition temperature of 200 to 500 ° C.,
The first organic solvent is a liquid at room temperature, has a boiling point of 200 ° C. or higher, but does not exceed 400 ° C., and does not contain any reactive functional groups other than hydroxyl groups. An organic solvent having a group,
The copper salt of the aliphatic monocarboxylic acid is mixed with the first organic solvent as a solution obtained by dissolving in a (dialkylamino) alkylamine, to obtain a mixed solution,
A paste-like composition in which the copper powder and the fine copper powder are dispersed in the mixed solution; and
The average particle diameter of the copper powder is selected in the range of 2 μm to 10 μm,
The average particle diameter of the fine copper powder is selected in the range of 0.2 μm to 1.0 μm,
The copper salt of the aliphatic monocarboxylic acid has a boiling point of 230 ° C. or higher, but is derived from an aliphatic monocarboxylic acid (R—COOH) that does not exceed 400 ° C. Copper salt,
The (dialkylamino) alkylamine is a liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C.
The content ratio of the copper powder and the fine copper powder, (copper powder content) :( fine copper powder content) is selected in the range of 80 parts by mass: 20 parts by mass to 60 parts by mass: 40 parts by mass. ,
The total weight of copper atoms contained in the copper salt of the aliphatic monocarboxylic acid (W _{Cu-carboxylate} ) with respect to the total weight of the copper powder and the fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) The ratio of (W _Cu-powder + W _{Cu-fine-powder} ) :( W _{Cu-carboxylate} ) is selected in the range of 100 parts by mass: 0.15 parts by mass to 100 parts by mass: 0.7 parts by mass,
The ratio of the total weight (W _Cu-powder + W _{Cu-fine-powder} ) of the copper powder and fine copper powder to the weight of the first organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu -fine-powder} ): W _{dispersion-medium} is selected in the range of 100 parts by mass: 2 parts by mass to 100 parts by mass: 10 parts by mass,
The content ratio of the aliphatic monocarboxylic acid copper salt and the (dialkylamino) alkylamine is such that (dialkylamino) alkylamine is 2.2 to 8 molecules per molecule of the aliphatic monocarboxylic acid copper salt. A paste-like composition selected in a range ratio;
After applying the conductive copper paste on the resin base material, the conductive film is formed by irradiating with light in a state where the residual amount of the first organic solvent is 0.1 to 5% by mass. A method for producing a membrane. A method for producing a conductive film using a conductive copper paste not containing a thermosetting resin component or glass frit,
The conductive copper paste is
Copper powder, fine copper powder, copper salt of aliphatic monocarboxylic acid, (dialkylamino) alkylamine, polymer binder, and second organic solvent,
The polymer binder has a thermal decomposition temperature of 200 to 500 ° C.,
The second organic solvent is an aliphatic polyhydric alcohol that is liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 400 ° C.
The copper salt of the aliphatic monocarboxylic acid is mixed with the second organic solvent as a solution obtained by dissolving in a (dialkylamino) alkylamine, to obtain a mixed solution,
A paste-like composition in which the copper powder and the fine copper powder are dispersed in the mixed solution; and
The average particle diameter of the copper powder is selected in the range of 2 μm to 10 μm,
The average particle diameter of the fine copper powder is selected in the range of 0.2 μm to 1.0 μm,
The copper salt of the aliphatic monocarboxylic acid has a boiling point of 230 ° C. or higher, but is derived from an aliphatic monocarboxylic acid (R—COOH) that does not exceed 400 ° C. Copper salt,
The (dialkylamino) alkylamine is a liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C.
The content ratio of the copper powder and the fine copper powder, (copper powder content) :( fine copper powder content) is selected in the range of 80 parts by mass: 20 parts by mass to 60 parts by mass: 40 parts by mass. ,
The total weight of copper atoms contained in the copper salt of the aliphatic monocarboxylic acid (W _{Cu-carboxylate} ) with respect to the total weight of the copper powder and the fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) The ratio of (W _Cu-powder + W _{Cu-fine-powder} ) :( W _{Cu-carboxylate} ) is selected in the range of 100 parts by mass: 0.15 parts by mass to 100 parts by mass: 0.7 parts by mass,
The ratio of the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the weight of the second organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu -fine-powder} ): W _{dispersion-medium} is selected in the range of 100 parts by mass: 2 parts by mass to 100 parts by mass: 10 parts by mass,
The content ratio of the aliphatic monocarboxylic acid copper salt and the (dialkylamino) alkylamine is such that (dialkylamino) alkylamine is 2.2 to 8 molecules per molecule of the aliphatic monocarboxylic acid copper salt. A paste-like composition selected in a range ratio;
After applying the conductive copper paste on the resin base material, the conductive film is formed by irradiating with light in a state where the residual amount of the second organic solvent is 0.1 to 5% by mass. A method for producing a membrane. A method for producing a conductive film using a conductive copper paste not containing a thermosetting resin component or glass frit,
The conductive copper paste is
Including copper powder, fine copper powder, copper nanoparticles, (dialkylamino) alkylamine, polymer binder, and a third organic solvent,
The polymer binder has a thermal decomposition temperature of 200 to 500 ° C.,
The third organic solvent is a liquid at room temperature, has a boiling point of 200 ° C. or higher, but does not exceed 400 ° C., and has no reactive functional groups other than hydroxyl groups. An organic solvent having a group,
The copper nanoparticles are mixed with the third organic solvent as a dispersion dispersed in (dialkylamino) alkylamine, to form a mixed solution,
A paste-like composition in which the copper powder and the fine copper powder are dispersed in the mixed solution; and
The average particle size of the copper powder is selected in the range of 2 to 10 μm,
The average particle diameter of the fine copper powder is selected in the range of 0.2 to 1.0 μm,
The average particle diameter of the copper nanoparticles is selected in the range of 10 nm to 100 nm,
The (dialkylamino) alkylamine is a liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C.
The content ratio of the copper powder and the fine copper powder, (copper powder content) :( fine copper powder content) is selected in the range of 80 parts by mass: 20 parts by mass to 60 parts by mass: 40 parts by mass. ,
The ratio of the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the weight of the third organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu -fine-powder} ): W _{dispersion-medium} is selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 10 parts by mass,
The ratio of the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ) to the total weight of the copper nanoparticles (W _{Cu-nano-particle} ), (W _Cu-powder + W _{Cu-fine-powder} ) :( W _{Cu-nano-particle} ) is selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 15 parts by mass,
The content ratio of the copper nanoparticles and the (dialkylamino) alkylamine is the ratio of the total volume of copper nanoparticles (V _{Cu-nano-particle} ) to the volume of (dialkylamino) alkylamine (V _{dispersion-medium} ). , (V _{Cu-nano-particle} ): V _amine is a paste-like composition selected in the range of 10:50 to 10: 100;
After applying the conductive copper paste on the resin base material, the conductive film is formed by irradiating with light in a state where the residual amount of the third organic solvent is 0.1 to 5% by mass. A method for producing a membrane. A method for producing a conductive film using a conductive copper paste not containing a thermosetting resin component or glass frit,
The conductive copper paste is
Including copper powder, fine copper powder, copper nanoparticles, (dialkylamino) alkylamine, polymer binder, and a fourth organic solvent,
The polymer binder has a thermal decomposition temperature of 200 to 500 ° C.,
The fourth organic solvent is an aliphatic polyhydric alcohol that is liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 400 ° C.,
The copper nanoparticles are mixed with the fourth organic solvent as a dispersion liquid dispersed in (dialkylamino) alkylamine, to form a mixed liquid,
A paste-like composition in which the copper powder and the fine copper powder are dispersed in the mixed solution; and
The average particle diameter of the copper powder is selected in the range of 2 μm to 10 μm,
The average particle diameter of the fine copper powder is selected in the range of 0.2 μm to 1.0 μm,
The average particle diameter of the copper nanoparticles is selected in the range of 10 nm to 100 nm,
The (dialkylamino) alkylamine is a liquid at room temperature and has a boiling point of 230 ° C. or higher but not exceeding 300 ° C.
The content ratio of the copper powder and the fine copper powder, (copper powder content) :( fine copper powder content) is selected in the range of 80 parts by mass: 20 parts by mass to 60 parts by mass: 40 parts by mass. ,
The ratio of the total weight of copper atoms (W _{Cu-nano-particle} ) in the copper nanoparticles to the total weight of the copper powder and fine copper powder (W _Cu-powder + W _{Cu-fine-powder} ), (W _Cu-powder + W _{Cu-fine-powder} ): (W _{Cu-nano-particle} ) is selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 15 parts by mass,
The ratio of the total weight (W _Cu-powder + W _{Cu-fine-powder} ) of the copper powder and fine copper powder to the weight of the fourth organic solvent (W _{dispersion-medium} ), (W _Cu-powder + W _{Cu -fine-powder} ): W _{dispersion-medium} is selected in the range of 100 parts by mass: 3 parts by mass to 100 parts by mass: 10 parts by mass,
The content ratio of the copper nanoparticles and the (dialkylamino) alkylamine is the ratio of the total volume of copper nanoparticles (V _{Cu-nano-particle} ) to the volume of (dialkylamino) alkylamine (V _{dispersion-medium} ). , (V _{Cu-nano-particle} ): V _amine is a paste-like composition selected in the range of 10:50 to 10: 100;
After applying the conductive copper paste on the resin base material, the conductive film is formed by irradiating with light in a state where the residual amount of the fourth organic solvent is 0.1 to 5% by mass. A method for producing a membrane.   The ratio (copper / polymer binder) of the mass of the copper component obtained by adding the copper powder, the fine copper powder and the copper salt of the aliphatic monocarboxylic acid to the mass of the polymer binder is 70/30 to 98/2. The method for producing a conductive film according to claim 1 or 2.   The ratio (copper / polymer binder) of the mass of the copper component obtained by adding the copper powder, the fine copper powder and the copper nanoparticles to the mass of the polymer binder is 70/30 to 98/2. Or the manufacturing method of the electrically conductive film of 4.   The method for producing a conductive film according to any one of claims 1 to 6, wherein a glass transition temperature of the resin base material is 50 to 400 ° C.   The method for producing a conductive film according to claim 1, wherein the conductive copper paste further contains copper oxide.   The method for producing a conductive film according to claim 1, wherein the conductive copper paste further contains silver nanoparticles.