JP2021059659A - Conductive composition - Google Patents

Abstract

To provide a conductive composition that has excellent screen print quality and conductivity and allows soldering.SOLUTION: A conductive composition contains, based on (a) conductive particles 100 pts.mass, (B) a C8-24 aliphatic monocarboxylic acid of 0.1-5 pts.mass, (c) an amine compound represented by formula (1) of 0.1-5 pts.mass, and (d) a binder resin of 3-20 pts.mass. [In formula (1), k is an integer of 1-3, R1 is selected from a hydrogen atom, aminoethyl, and phenyl, R2-R4 independently represent methyl or ethyl].SELECTED DRAWING: None

Description

The present invention relates to a conductive composition that is excellent in screen printability and conductivity and can be soldered.

In recent years, in the field of electronic component mounting and the like, in contrast to the conventional technique of forming a conductive circuit represented by a printed circuit board by patterning a copper foil by etching, a conductive metal particle such as a silver paste is used as a main component. Attention has been focused on alternative techniques for forming a conductive circuit by thermally curing a conductive composition after printing it by screen printing or the like. A conductive circuit formed from a conductive composition has features such as being able to be easily formed on various substrates and being formed in an arbitrary pattern on substrates of various shapes. There is also an example that is applied in.

A conductive composition using copper particles as conductive metal particles is cheaper than a conductive composition using silver particles and can exhibit conductivity equivalent to that of silver, and therefore research is underway.
For example, Patent Document 1 reports that the oxidation of copper during curing can be suppressed by combining an aliphatic monocarboxylic acid, an amine, and 4-aminosalicylic acid.
Further, in Patent Document 2, a conductive paste combining metal particles treated with an aqueous surface treatment agent, a coupling agent, an organic carboxylic acid, a chelating agent, and a surfactant has excellent oxidation resistance and causes ion migration. It has been reported to be difficult.

International Publication No. 2017/029953 Japanese Unexamined Patent Publication No. 2019-131496

However, although the conductive circuit formed by using the conductive composition disclosed in Patent Documents 1 and 2 is excellent in screen printability and conductivity, it is soldered as compared with the conductive circuit made of copper foil. Poor sex is a problem. If electronic components cannot be mounted by soldering, the mounting method of electronic components is limited to anisotropic conductive conductive films and anisotropic conductive pastes with low bonding strength, resulting in insufficient mechanical reliability of the device and at the same time. There is a problem that it cannot be used in applications where a high current flows.
Therefore, an object of the present invention is to provide a conductive composition having excellent screen printability and conductivity and which can be soldered.

As a result of diligent studies in view of the above problems, the present inventors have found that the above problems can be solved by a conductive composition having a specific composition, and have completed the present invention.
That is, the present invention is represented by (a) 0.1 to 5 parts by mass of an aliphatic monocarboxylic acid having 8 to 24 carbon atoms with respect to 100 parts by mass of conductive particles, and (c) formula (1). It is a conductive composition containing 0.1 to 5 parts by mass of an amine compound and 3 to 20 parts by mass of (d) binder resin.

[In formula (1), k is an integer of 1 to 3, R ¹ is any of a hydrogen atom, aminoethyl, and phenyl, and R ^{2 to} R ⁴ are independently methyl or ethyl, respectively. .. ]

Since the conductive composition of the present invention can form a cured film which is excellent in screen printability and conductivity and can be soldered, it can be soldered onto a circuit formed of the conductive composition of the present invention. Electronic components can be mounted. By doing so, it is possible to form electronic circuits on various types and shapes of base materials by taking advantage of the features of printed wiring, and to create highly reliable electronic devices while improving the design of the devices. Is possible.

Hereinafter, embodiments of the present invention will be described in detail.
In this specification, when a preferable numerical range (for example, a range of content) is described stepwise, each lower limit value and upper limit value can be combined independently. For example, the description "preferably 10 to 100, more preferably 20 to 90" can be changed to "10 to 90", "20 to 100", "10 to 20" or "90 to 100". In addition, the numerical range defined by using the symbol "~" shall include the numerical values at both ends (upper limit value and lower limit value) of "~". For example, "2-5" represents 2 or more and 5 or less.

The conductive composition of the present invention comprises (a) conductive particles, (b) an aliphatic monocarboxylic acid having 8 to 24 carbon atoms, (c) an amine compound represented by the formula (1), and (d) a binder resin. At least contains.
Hereinafter, each component will be described.

<Component (a): Conductive particles>
The component (a) used in the present invention is a conductive particle, and inorganic conductive particles such as copper particles can be used. The copper particles are not particularly limited, and known copper particles generally used for copper paste and copper ink can be used.
The copper particles may consist only of copper, but may further contain metals other than copper such as silver and platinum, metal oxides, and metal sulfides, and may form surface layers or protrusions. It may be in shape. When the copper particles further contain a metal other than copper, a metal oxide, and a metal sulfide, the mass ratio of copper in the copper particles is preferably 50% by mass or more.

Commercially available conductive particles may be used as they are, but it is preferable to use surface-coated conductive particles whose surface is coated for the purpose of improving oxidation resistance. Among them, it is preferable to use surface-coated conductive particles whose surface is coated with an amine compound, and it is more preferable to use surface-coated conductive particles whose surface is coated with an amine compound represented by the following formula (2).

[In equation (2), m is an integer of 0 to 3, n is an integer of 0 to 2, and when n = 0, m is any of 0 to 3, and when n = 1 or n = 2. m is one of 1 to 3. ]

The surface-coated conductive particles whose surface is coated with the amine compound are preferably surface-coated conductive particles further coated with an aliphatic monocarboxylic acid from the viewpoint of obtaining better oxidation resistance.
As a result, the surface of the conductive particles is coated with the first coating layer formed of the amine compound and the second coating layer formed of the aliphatic monocarboxylic acid. Preferably, the first coating layer is formed on the surface of the conductive particles and the second coating layer is formed on the first coating layer.

As the aliphatic monocarboxylic acid forming the second coating layer, an aliphatic monocarboxylic acid having 8 to 20 carbon atoms is preferable. Examples of the aliphatic monocarboxylic acid include a linear saturated aliphatic monocarboxylic acid, a linear unsaturated aliphatic monocarboxylic acid, a branched saturated aliphatic monocarboxylic acid, and a branched unsaturated aliphatic monocarboxylic acid. Examples of linear saturated aliphatic monocarboxylic acids having 8 to 20 carbon atoms include caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, and stearic acid. Examples include acid, nonadecylic acid and lauric acid. Examples of the linear unsaturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include myristoleic acid, palmitoleic acid, petroselinic acid, and oleic acid. Examples of the branched saturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include 2-ethylhexanoic acid. As the aliphatic monocarboxylic acid, one selected from the above compounds may be used alone, or two or more thereof may be used in combination.

The method for producing the surface-coated conductive particles is not particularly limited. As a method for obtaining surface-coated conductive particles whose surface is coated with an amine compound, for example, it is necessary to wash the conductive particles with an aqueous solution of ammonium chloride or the like, and then add the washed conductive particles to a solution of the amine compound. There is a method of heating according to the above.
As a method for producing surface-coated conductive particles coated with a first coating layer formed of an amine compound and a second coating layer formed of an aliphatic monocarboxylic acid, for example, the surface is coated with an amine compound. A method of adding the surface-coated conductive particles to the solution of the aliphatic monocarboxylic acid can be mentioned. After being added to the solution of the aliphatic monocarboxylic acid, it can be heated if necessary.

The average particle size of the conductive particles is not particularly limited, but the average particle size (D50) is 0.1 to 10 μm for use in a conductive composition for screen printing having excellent continuous printability. Is preferable. Further, from the viewpoint of suppressing clogging of the plate during printing, the average particle size (D50) is more preferably 0.1 to 8 μm, and further preferably 0.1 to 5 μm.
If the average particle size of the conductive particles is too large, the filling rate of the conductive particles becomes low, it becomes difficult to form a conductive path, and it becomes difficult to prepare a cured film having a resistance value sufficient to activate electronic components. May become. Further, if the average particle size of the conductive particles is too small, the solderability may be sharply lowered. Although the reason for this is not clear, it is presumed that the unevenness on the surface of the cured film is reduced and the convex metal portion that contributes to the solder wettability is reduced.

The average particle size of the conductive particles means a value obtained by additively averaging the ferret diameters of 100 randomly selected particles obtained by observing with a transmission electron microscope or a scanning electron microscope. It shall be.

Preferably the specific surface area of the conductive particles is 0. 1~1. 0m ² / g, more preferably 0.15~0.6m ² / g.
The BET specific surface area of the conductive particles can be measured by the BET one-point method using a specific surface area measuring device (“Monosorb” manufactured by Yuasa Ionics Co., Ltd.).

There is no particular limitation on the shape and aspect ratio (ratio of the major axis to the minor axis of the particles) of the conductive particles, such as spherical, polyhedral, flat, plate-like, flake-like, flaky, rod-like, dendritic, and fibrous. It may be any of the above, and it may be in an indefinite shape such as hollow or porous. Among these, spherical particles are preferable, and conductive particles having an aspect ratio of 0.9 to 1.0 on the major axis and the minor axis are particularly preferable.

As the conductive particles, one type selected from those having different constituents, average particle size, shape, aspect ratio, etc. may be used alone, or two or more types may be used in combination.

<Component (b): Aliphatic monocarboxylic acid having 8 to 24 carbon atoms>
The component (b) used in the present invention is an aliphatic monocarboxylic acid having 8 to 24 carbon atoms, preferably 10 to 20 carbon atoms.
If the carbon number of the aliphatic monocarboxylic acid is too short, the effect of dispersing the conductive particles becomes small, air bubbles are sandwiched in the conductive composition, and unevenness is likely to occur during curing. The unevenness of the cured film caused by air bubbles, unlike the unevenness derived from conductive particles, lowers the solder wettability and may make soldering difficult. Further, if the carbon number is too long, it may not be possible to obtain an effect commensurate with the increase in the carbon number, and it may be difficult to obtain the effect.

Examples of the aliphatic monocarboxylic acid include a linear saturated aliphatic monocarboxylic acid, a linear unsaturated aliphatic monocarboxylic acid, a branched saturated aliphatic monocarboxylic acid, and a branched unsaturated aliphatic monocarboxylic acid.
Examples of linear saturated aliphatic monocarboxylic acids having 8 to 24 carbon atoms include caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, and stearic acid. Examples include acids, nonadecylic acid, lauric acid, bechenic acid and lignoseric acid. Examples of the linear unsaturated aliphatic monocarboxylic acid having 8 to 24 carbon atoms include myristoleic acid, palmitoleic acid, petroselinic acid, and oleic acid. Examples of the branched saturated aliphatic monocarboxylic acid having 8 to 24 carbon atoms include 2-ethylhexanoic acid.

As the component (b), one selected from the above compounds may be used alone, or two or more thereof may be used in combination. In particular, a linear saturated aliphatic monocarboxylic acid having 8 to 24 carbon atoms is preferable, and it is preferable to use one or more selected from lauric acid, myristic acid, palmitic acid, and stearic acid from the viewpoint of conductivity. Lauric acid is more preferable from the viewpoint of conductivity.

The content of the component (b) in the conductive composition is 0.1 to 5 parts by mass, preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the conductive particles of the component (a). , More preferably 0.1 to 3.0 parts by mass, still more preferably 0.1 to 1.0 parts by mass.
If the content of the component (b) is too small, the dispersibility of the conductive particles is lowered, and the same phenomenon as when the carbon number of the aliphatic monocarboxylic acid is too short occurs, which makes soldering difficult. There is. Further, if the content of the component (b) is too large, the excess aliphatic monocarboxylic acid may hinder the adhesion between the paste-like conductive composition and the base material.

<Component (c): Amine compound represented by the formula (1)>
The component (c) used in the present invention is an amine compound represented by the following formula (1).

In equation (1), k is an integer of 1-3. From the viewpoint of availability, the one with k = 3 is preferable.
R ¹ is any of hydrogen atom, aminoethyl, and phenyl. Hydrogen and phenyl are preferable when screen printability is to be improved, and aminoethyl is preferable when solderability is to be improved. R ^{2 to} R ⁴ are each independently methyl or ethyl.

Specifically, as the component (c), 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (amino). Ethyl) -3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane and the like can be mentioned.

The content of the component (c) in the conductive composition is 0.1 to 5 parts by mass, preferably 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the conductive particles of the component (a). , More preferably 0.1 to 3.0 parts by mass, still more preferably 0.1 to 1.0 parts by mass.
If the content of the component (c) is too small, the solder wettability may be lowered, and the cured film may be easily oxidized during soldering. If the content of the component (c) is too large, the excess amount of the amine compound may act as an impurity to reduce the conductivity.

[Component (d): Binder resin]
The component (d) used in the present invention is a binder resin.
As the component (d), a known binder resin used for conductive paste or the like can be used. For example, epoxy resin, melamine resin, phenol resin, silicon resin, oxazine resin, urea resin, polyurethane resin, unsaturated polyester. Examples thereof include resins, vinyl ester resins, xylene resins, acrylic resins, oxetane resins, diallyl phthalate resins, oligoester acrylate resins, bismalade triazine resins and furan resins. Any one of these binder resins may be used alone, or two or more thereof may be mixed and used.

Among these, a resin showing a condensation reaction is preferable. Since the resin exhibiting a condensation reaction has a large curing shrinkage, the conductive particles are closer to each other, and a cured product having good conductivity can be obtained. Specifically, a resin showing dehydration condensation such as a phenol resin is more preferable. Further, by using a phenol resin, it becomes easy to obtain a cured product having high conductivity even if it is cured at a relatively low temperature.

Among the phenol resins, the resol type phenol resin is preferable. By using the resol type phenol resin, it is possible to suppress the surface oxidation of the conductive particles and facilitate the improvement of the conductivity of the cured product. Specific examples of the resol-type phenol resin include unmodified resol-type phenol resins produced from phenols and aldehydes; modified resol-type phenols produced by adding various modifiers to phenols and aldehydes. Examples include resin.
The resole-type phenol resin is also available as a commercial product. Examples of commercially available resole-type phenolic resins include REGITOP (registered trademark) PL-5208, PL-2407, and PL-6317 (manufactured by Gun Ei Chemical Industry Co., Ltd.). One type of resole-type phenol resin may be used alone, or two or more types may be used in combination.

The content of the component (d) in the conductive composition is 3 to 20 parts by mass, preferably 5 to 15 parts by mass, and more preferably 6 to 6 to 15 parts by mass with respect to 100 parts by mass of the conductive particles of the component (a). It is 10 parts by mass.
If the content of the component (d) is small, the solderability is high, but if it is too small, the adhesion to the base material to which the cured film formed from the conductive composition adheres may be significantly lowered. .. Further, if the content of the component (d) is large, the screen printability is high, but if it is too large, the excess binder resin may hinder the solder wettability and the solder wettability may be significantly lowered.

The cured film formed from the conductive composition of the present invention has excellent solderability. The reason why such an effect is obtained is not clear, but it is presumed as follows.
In this composition, since the content of the conductive particles of the component (a) is higher than that of the general composition, the amount of the binder resin of the component (d) is relatively small, and the composition is exposed to the atmospheric surface. There are many conductive particles. As a result, conductive particles such as copper particles having low oxidation resistance may be oxidized and the conductivity of the cured film may be lowered.
However, this composition contains the aliphatic monocarboxylic acid of the component (b), and the aliphatic monocarboxylic acid coats the surface of the conductive particles instead of the binder to suppress surface oxidation and conduct the cured film. Deterioration of sex is suppressed. On the other hand, when a high amount of heat is applied during soldering, the aliphatic monocarboxylic acid that coats the surface of the conductive particles becomes above the melting point and melts to expose the surface of the conductive particles, so that the solder wettability is not hindered.

Further, although the exact mechanism of action of the amine compound of the component (c) is unknown, the nitrogen atom contained in the amine compound has a high effect of preventing the oxidation of conductive particles such as copper particles, and particularly of the component (b). The antioxidant effect is enhanced when used in combination with an aliphatic monocarboxylic acid. Further, the amine compound of the component (c), like the flux component contained in the solder, peels off and removes the oxide film on the surface of the conductive particles at the time of solder bonding to promote alloying, and bonding by alloying occurs. It is considered that the solder wettability to the metal part is easily improved by forming an interface that is firmly adhered to the part that is not covered by the effect of the silane coupling agent.

<Diluent>
The conductive composition of the present invention may contain a diluent.
Examples of the diluent include ether-based alcohols, non-ether-based alcohols, esters, ketones, terpenes, and other hydrocarbons.

Examples of ether-based alcohols include diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-isopropyl ether, ethylene glycol mono-n-butyl ether, and ethylene glycol dimethyl ether. , Ethylene glycol methyl ethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, ethylene Examples thereof include glycol monomethyl ether, diethylene glycol monoethyl ether acetate, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and propylene glycol monomethyl ether. In particular, it is preferable to use diethylene glycol monoethyl ether or diethylene glycol monoethyl ether acetate in terms of coatability on a substrate.

Examples of non-ether alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol and the like.

Examples of the esters include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, diethyl malonate and the like.

Examples of the ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like.

Examples of terpenes include turpentine, turpentine, borneol, α-pinene and the like. In particular, it is preferable to use telepineol in terms of conductivity and coating property on a substrate.

Other hydrocarbons include tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, diacetone alcohol, propylene carbonate and the like. Can be mentioned.

When the conductive composition contains a diluent in order to improve the coatability on the base material, the content thereof is preferably 5 to 30 parts by mass with respect to 100 parts by mass of the conductive particles of the component (a). It is more preferably 10 to 20 parts by mass.

<Conductive composition>
The conductive composition of the present invention contains at least the components (a) to (d), and further contains a diluent if necessary. The total content of each of these components is preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 100% by mass, based on the total amount of the conductive composition.

In addition to the above-mentioned components, various additives can be added to the conductive composition of the present invention as needed. For example, a surfactant, a dispersant, a curing agent, an antioxidant, and a conductive composition can be added. Auxiliary agents, antifoaming agents, and other additives may be blended.

The conductive composition of the present invention can be produced by mixing the components (a) to (d), and if necessary, a diluent and other additives with a kneading device or the like. Examples of the kneading device include a three-roll mill, an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill, an impeller, a desperzer, a KD mill, a colloid mill, a dynatron, a planetary mill, and a pressurized kneader. Can be used.

<Laminated body>
The conductive composition of the present invention can be applied onto the surface of a base material to form a coating film, and then the coating film can be cured to form a cured product. In this way, a laminate having a base material and a cured product of the conductive composition provided on the base material can be obtained.

Examples of the base material to which the conductive composition is applied include polyimide (PI), polyamideimide (PAI), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and polyether sulfone (PES). ), Fluororesin, resin base material such as liquid crystal polymer; ceramic base material; glass base material; metal base material and the like. The conductive composition of the present invention is applied to a base material, heat-cured, and then electronic components are mounted by soldering. Therefore, it is preferable to select a base material that is not denatured by heat during soldering.

As a method of applying the conductive composition to the substrate, a desired method such as casting method, gravure printing, screen printing, coating using a coater, spin coating and the like can be adopted. This composition exhibits excellent printability especially in screen printing.

The conductive composition of the present invention can be cured at a relatively low temperature to obtain a cured product having good conductivity. Therefore, the conditions for curing the coating film are preferably 80 to 200 ° C., more preferably 120 to 150 ° C., and preferably 5 to 30 minutes when the coating film is cured in a hot air circulation oven or the like. When curing with an infrared heater or the like, the surface temperature of the coating film is preferably 80 to 200 ° C., and the curing time is preferably 0.5 to 15 minutes. Furthermore, both a hot air circulation oven and an infrared heater can be combined and cured. When a substrate having low heat resistance such as a paper substrate is used, it is preferable to cure it at a low temperature of 160 ° C. or lower.

Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
The conductive compositions produced by the methods of each Example and Comparative Example were evaluated by the following evaluation methods.

<Judgment of screen printability>
The conductive composition produced by the methods of each Example and Comparative Example was developed on a screen plate (SUS200) on which a comb-shaped pattern of L / S = 500 μm / 500 μm was drawn, and was developed on a screen printing machine (MT-320, It was applied onto a glass substrate at a printing speed of 50 mm / sec by Microtech). The printed shape of the conductive composition patterned on the glass substrate was evaluated by visual observation according to the following criteria.
〔Evaluation criteria〕
No rubbing / missing on the print pattern: ◎ (extremely good)
No defects in print pattern: ○ (good)
Rubbed / defective print pattern: × (defective)

<Judgment of conductivity of cured product>
The volume resistivity of the cured product of the conductive composition produced by the methods of each Example and Comparative Example was evaluated by the method shown below in accordance with JIS K7194.
〔Evaluation method〕
Measuring equipment type: Low resistivity meter MCP-T610 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.)
Measurement conditions: 4 probe method Probe: ASP
Measurement sample (cured product): The volume resistivity of the cured product obtained by applying the conductive composition on the substrate so as to have a width of 1 cm, a length of 3 cm, and a thickness of 30 μm and then curing at 150 ° C. × 15 minutes. Was measured.
Number of measurements: Measured 5 times and calculated the average value of volume resistivity.

<Judgment of solderability>
The solderability of the cured product of the conductive composition produced by the methods of each Example and Comparative Example was evaluated by evaluating the wettability of the solder to the cured film. Specifically, it was evaluated by the method shown below.
After applying the conductive composition on the base material so as to have a width of 1 cm, a length of 3 cm, and a thickness of 30 μm, a base material with a cured film was obtained at 150 ° C. × 15 minutes, and then a tin / lead bar solder was obtained. Was melted with a soldering iron at 250 ° C. and solder was bonded onto the cured film. Then, the contact angle of the solder on the cured film was measured with a contact angle meter and evaluated according to the following criteria.
〔Evaluation criteria〕
Contact angle less than 60 °: ◎ (extremely good)
Contact angle 60 ° or more and less than 90 °: ○ (good)
Contact angle 90 ° or more: × (defective)

(Example 1)
An aqueous ammonium chloride solution prepared by dissolving 5 g of ammonium chloride in 1000 g of water. 500 g of spherical copper particles 1200Y [particle size (D50) 2.1 μm, specific surface area 0.39 m ² / g] manufactured by Mitsui Mining & Smelting Co., Ltd. was added to the ammonium chloride aqueous solution, and under nitrogen bubbling, at 30 ° C. for 60 minutes. Stirred. A mechanical stirrer was used for stirring, and the stirring was performed at a rotation speed of 150 rpm. Hereinafter, stirring was performed at the same rotation speed using the same stirring device. After the stirring was completed, the copper particles were filtered off by vacuum filtration using a Kiriyama funnel of 5C filter paper, and subsequently, the copper particles were washed twice with 150 g of water on the Kiriyama funnel.
The washed copper particles were added to 2500 g of a 40% by mass diethylenetriamine aqueous solution, and the mixture was heated and stirred at 60 ° C. for 1 hour while carrying out nitrogen bubbling.
After the stirring was stopped and the mixture was allowed to stand for 5 minutes, about 2000 g of the supernatant was withdrawn and removed. Subsequently, 2000 g of isopropanol was added to the precipitate as a cleaning solvent, and the mixture was stirred at 30 ° C. for 3 minutes. After the stirring was stopped and the mixture was allowed to stand for 5 minutes, about 2000 g of the supernatant was withdrawn and removed. Then, 2500 g of a 2 mass% isopropanol solution of laurate was added, and the mixture was stirred at 30 ° C. for 30 minutes. After the stirring was completed, the copper particles were filtered off by vacuum filtration using a Kiriyama funnel of 5C filter paper. The obtained copper particles were dried under reduced pressure at 25 ° C. for 3 hours to obtain surface-coated copper particles.

100 parts by mass of surface-coated copper particles treated by the above method, 0.5 parts by mass of lauric acid, 0.5 parts by mass of 3-aminopropyltrimethoxysilane (amine compound C1 in Table 1), antioxidants 2, 2 '-Vipyridyl 0.6 parts by mass, Resol type phenol resin solution (PL-5208, manufactured by Gunei Chemical Industry Co., Ltd.) 15.7 parts by mass (solid content Resol type phenol resin 9.2 parts by mass, with solvent A certain ethyl carbitol (6.5 parts by mass) and the diluting solvent were mixed so as to be 10 parts by mass including ethyl carbitol derived from the resin.
Next, using a planetary mixer [ARV-310, manufactured by Shinky Co., Ltd.], the mixture was stirred at a rotation speed of 1500 rpm for 30 seconds at room temperature for primary kneading.
Next, using a 3-roll mill [EXAKT-M80S, manufactured by Nagase Screen Printing Laboratory Co., Ltd.], the conductive composition is subjected to secondary kneading by passing it 5 times under the conditions of room temperature and a distance between rolls of 5 μm. Got
The obtained conductive composition was evaluated for screen printability, conductivity of the cured product, and solderability, respectively. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

(Example 2)
A conductive composition was prepared in the same manner as in Example 1 except that the solid content of the resole-type phenol resin was 7.5 parts by mass, and each evaluation was carried out in the same manner as in Example 1. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

(Example 3)
A conductive composition was prepared in the same manner as in Example 1 except that the solid content of the resole-type phenol resin was 3.7 parts by mass, and each evaluation was carried out in the same manner as in Example 1. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

(Example 4)
A conductive composition was prepared in the same manner as in Example 2 except that the aliphatic monocarboxylic acid was changed to stearic acid, and each evaluation was carried out in the same manner as in Example 1. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

(Example 5)
A conductive composition was prepared in the same manner as in Example 2 except that the aliphatic monocarboxylic acid was changed to oleic acid, and each evaluation was carried out in the same manner as in Example 1. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

(Example 6)
A conductive composition was prepared in the same manner as in Example 2 except that the amine compound was changed to N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (amine compound C2 in Table 1), and Examples were prepared. Each evaluation similar to 1 was performed. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

(Example 7)
A conductive composition was prepared in the same manner as in Example 2 except that the amine compound was changed to N-phenyl-3-aminopropyltrimethoxysilane (amine compound C3 in Table 1), and each of the same as in Example 1. Evaluation was performed. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

(Comparative Example 1)
A conductive composition was prepared in the same manner as in Example 2 except that the aliphatic monocarboxylic acid was changed to caproic acid, and each evaluation was carried out in the same manner as in Example 1. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

(Comparative Example 2)
A conductive composition was prepared in the same manner as in Example 2 except that the amine compound was changed to triethanolamine, and each evaluation was carried out in the same manner as in Example 1. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

(Comparative Example 3)
A conductive composition was prepared in the same manner as in Example 2 except that the amine compound was not used, and each evaluation was carried out in the same manner as in Example 1. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

(Comparative Example 4)
A conductive composition was prepared in the same manner as in Example 2 except that the aliphatic monocarboxylic acid was not used, and each evaluation was carried out in the same manner as in Example 1. Table 2 shows the blending amount of each component of the conductive composition and the evaluation results.

Table 1 shows the relationship between the amine compounds C1 to C3 used in the examples and the structure of the formula (1).

As shown in Table 2, the conductive composition of each example satisfying the requirements of the present invention has good screen printability and the conductivity of the cured product is 50 μΩ · cm or less, which is suitable for wiring circuits for electronic components. It was a usable resistance value. It was also possible to solder.
On the other hand, in Comparative Example 1, since an aliphatic monocarboxylic acid other than this requirement was used, the solderability was lowered.
In Comparative Example 2, since an amine compound other than this requirement was used, all of the printability, conductivity, and solderability were deteriorated.
In Comparative Example 3, since the amine compound was not used, the conductivity and solderability were lowered.
In Comparative Example 4, since the aliphatic monocarboxylic acid was not used, all of the printability, the conductivity, and the solderability were deteriorated.

Claims (1)

(A) With respect to 100 parts by mass of conductive particles
(B) 0.1 to 5 parts by mass of an aliphatic monocarboxylic acid having 8 to 24 carbon atoms.
(C) A conductive composition containing 0.1 to 5 parts by mass of an amine compound represented by the formula (1) and (d) 3 to 20 parts by mass of a binder resin.

[In formula (1), k is an integer of 1 to 3, R ¹ is any of a hydrogen atom, aminoethyl, and phenyl, and R ^{2 to} R ⁴ are independently methyl or ethyl, respectively. .. ]