KR20150083434A - Conductive paste and substrate with conductive film - Google Patents

Abstract

An object of the present invention is to provide a conductive paste which is excellent in conductivity and can form a conductive film having excellent resistance to bending, high temperature and high humidity, and a conductive film formed using such conductive paste. (A) an aromatic carboxylic acid ester compound selected from the group consisting of benzoic acid, phthalic acid, isophthalic acid and terephthalic acid and (B) metal particles having a volume resistivity of 10 mu OMEGA .cm or less and an average particle size of 0.5 to 15 mu m Provided that the total number of carbon atoms of the alkyl group is 40 or less when the number of the alkyl groups forming the ester bond is 40 or less); (C) a thermosetting resin having a benzene ring Wherein the metal particles of the component (A) are surface coated with a fatty acid having 8 to 20 carbon atoms, and the total amount of the component (C) is 100 parts by mass based on 100 parts by mass of the total components of the conductive paste, (B) is contained in an amount of from 5 to 25 parts by mass and the aromatic carboxylic acid ester compound (B) is contained in an amount of from 0.01 to 2.5 parts by mass Conductive paste.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a conductive paste,

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

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

The conductive paste used for the above purpose should have (1) good conductivity, (2) easy screen printing, intaglio printing, and (3) good adhesion of the coating film to the insulating substrate (4) capable of forming a fine wire circuit, (5) excellent solderability and solder strength on the coating film, and (6) conductivity of the solder coat circuit can be maintained over a long period of time.

In order to satisfy these requirements, the conductive paste is required to contain metal particles having a low specific resistance value such as copper or silver, a thermosetting resin such as phenol resin as a binder resin, a metal salt of saturated resin acid or unsaturated resin acid as a dispersing agent, (See Patent Document 1).

By forming the conductive film with the conductive paste having the above-described constitution, good conductivity can be ensured. However, when the conductive film is formed on the flexible film, there is a problem that the adhesiveness between the conductive film and the flexible film is poor, so that the electronic circuit is broken due to bending and the conductivity is damaged.

There has been proposed a conductive paste composition containing a conductive powder such as metal or carbon and a polyester resin having an acid value of 0.3 to 2.2 mgKOH / g as the conductive paste having a high bending resistance when the electronic circuit is formed on the flexible film Patent Document 2).

However, since the conductive paste described in Patent Document 2 uses a thermoplastic polyester resin having a flexible property as a binder resin, the conductive paste tends to be scratched and easily broken.

Japanese Patent Application Laid-Open No. 5-212579 Japanese Patent Application Laid-Open No. 2005-197226

Accordingly, an object of the present invention is to provide a conductive paste capable of forming a cured film having a certain degree of bending resistance and excellent durability under a high temperature and high humidity environment when an electronic circuit is formed on a flexible film.

(A) a metal particle having a volume resistivity of 10 mu OMEGA .cm or less and an average particle diameter of 0.5 to 15 mu m and (B) a metal particle having a volume resistivity of 10 mu OMEGA .cm or less and a group consisting of benzoic acid, phthalic acid, isophthalic acid and terephthalic acid (Provided that the alkyl group forming the ester bond is an alkyl group having 3 to 20 carbon atoms and the total number of carbon atoms in the alkyl group is 40 or less when a plurality of alkyl groups forming an ester bond are present) and an aromatic carboxylic acid ester compound (C) a binder resin containing a thermosetting resin having a benzene ring, wherein the metal particles of the component (A) are surface-coated with a fatty acid having 8 to 20 carbon atoms, and the total of the components of the conductive paste (C) component is contained in an amount of 5 to 25 parts by mass based on 100 parts by mass of the aromatic carboxylic acid ester (B) The compound provides a conductive paste characterized by containing 0.01 to 2.5 parts by weight.

In the conductive paste of the present invention, the metal particles of the component (A) are preferably copper particles or silver particles having an average particle diameter of 0.5 to 15 탆.

In the conductive paste of the present invention, the aromatic carboxylic acid ester compound as the component (B) is a phthalic acid ester compound represented by (ROOC) -C ₆ H ₄ - (COOR ') (wherein R and R' Is an alkyl group having 3 to 20 carbon atoms independently of each other provided that the total number of carbon atoms is 40 or less).

In the conductive paste of the present invention, the phthalic acid ester compound is preferably selected from the group consisting of dipropyl phthalate, diisopropyl phthalate, dibutyl phthalate, diisobutyl phthalate, dipentyl phthalate, diisopentyl phthalate, dihexyl phthalate, dihexyl phthalate, Heptyl phthalate, diheptyl phthalate, dioctyl phthalate, diisooctyl phthalate, diethylhexyl phthalate, dinonyl phthalate, diisononyl phthalate, dodecyl phthalate, diisodecyl phthalate, decyl undecyl phthalate, Diisodecyl phthalate, diisodecyl phthalate, ditordecyl phthalate, ditridecyl phthalate, diisotridecyl phthalate, ditetradecyl phthalate, diisotetradecyl phthalate, dipentadecyl phthalate, diisopentadecyl phthalate, phthalic acid di Hexadecyl phthalate, dihexadecyl phthalate, diheptadecyl phthalate, diheoheptadecyl phthalate, dioctadecyl phthalate, diisoctadecyl phthalate At least one member selected from the group consisting of phthalic acid dianodecyl, diisononadecyl phthalate, diacosyl phthalate and diisoekosyl phthalate is preferable.

In the conductive paste of the present invention, the binder resin of the component (C) is preferably at least one selected from the group consisting of a phenol resin, a cresol resin, an epoxy resin, an unsaturated polyester resin, a xylene resin and a polyimide.

The present invention also provides a substrate provided with a conductive film, characterized by having on the substrate a conductive film formed by coating and curing the conductive paste of the present invention.

In the substrate provided with the conductive film of the present invention, the substrate is preferably a flexible film.

According to the conductive paste of the present invention, it is possible to obtain a cured film having high conductivity and having a constant bending resistance. Specifically, the amount of change (increase) in resistivity (number of bending times: 10,000 times) measured before and after bending, which is measured in accordance with the procedure described in Examples to be described later, is 50 占 · m or less at initial value is 500% or less.

By using such a conductive paste, a substrate having a conductive film having high reliability as a flexible film wiring board or the like and suppressing deterioration of conductivity due to bending during use can be obtained.

Fig. 1 is a graph showing the relationship between the high temperature and high humidity test time and the change in resistivity for Examples 3 and 8. Fig.

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

≪ Conductive paste &

The conductive paste of the present invention is characterized in that (A) metal particles having a volume resistivity of 10 mu OMEGA .cm or less and an average particle diameter of 0.5 to 15 mu m and (B) a metal particle having a volume resistivity of 10 mu OMEGA- An aromatic carboxylic acid ester compound (provided that the alkyl group forming the ester bond is an alkyl group having 3 to 20 carbon atoms and the total number of carbon atoms in the alkyl group is 40 or less when a plurality of alkyl groups forming an ester bond are present) Wherein the metal particles of component (A) are surface-coated with a fatty acid having 8 to 20 carbon atoms or an alkylamine having 8 to 20 carbon atoms, and the whole of the conductive paste (C) is contained in an amount of 5 to 25 parts by mass, the phthalic acid ester compound (B) is contained in an amount of 0.01 To 2.5 parts by mass.

Hereinafter, each component constituting the conductive paste will be described in detail.

(A) metal particles

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

The metal particles of component (A) are required to have good conductivity. In the present invention, metal particles having a volume resistivity of 10 mu OMEGA .cm or less are used.

Examples of the metal that satisfies this requirement include gold, silver, copper, nickel, and aluminum. Of these, copper is particularly preferable because silver and copper are preferable because of low resistance value, availability, and migration difficulty.

The metal particles of the component (A) have an average value of the particle diameters defined by the following definitions, that is, an average particle diameter of 0.5 to 15 탆.

In the present specification, the particle diameter of the metal particles was measured by measuring the Feret diameter of 100 metal particles randomly selected from among the images of a scanning electron microscope (hereinafter referred to as " SEM "), (The Feret diameter in the major axis direction + the Feret diameter in the minor axis direction) of the major axis direction Feret diameter and the minor axis direction Feret diameter (when the major axis is the major axis and the major axis is the minor axis, / 2).

The particle diameter of the metal particles is the primary particle diameter of the metal particles.

In the present specification, the average value (average particle diameter) of the particle diameters of the metal particles is the average (number average) of the particle diameters of the metal particles calculated above.

(Average particle diameter) of the metal particles of the component (A) satisfies the above range, the flowability of the conductive paste containing the metal particles becomes favorable, and the fine wiring can be easily produced by the conductive paste. When the mean value (average particle diameter) of the particle diameters of the metal particles is less than 0.5 占 퐉, sufficient flow characteristics can not be obtained when the conductive paste is used. On the other hand, when the average value (average particle diameter) of the particle diameters of the metal particles exceeds 15 탆, there is a fear that the production of the fine wiring by the obtained conductive paste becomes difficult.

(Average particle diameter) of the metal particles of the component (A) is preferably 0.5 to 10 탆, more preferably 1 to 5 탆.

The metal particles of the component (A) are coated with a fatty acid having 8 to 20 carbon atoms or an alkylamine having 8 to 20 carbon atoms. The reason is as follows.

In order to disperse the metal particles in the binder resin of the component (C), it is necessary to lower the interface energy generated at the interface between the particles and the resin. In order to suppress aggregation of particles, it is necessary to form steric hindrance against aggregation between particles. The surface coating has a function of lowering the interfacial energy generated at the interface between the particles and the resin, thereby forming a steric hindrance against aggregation of the particles.

The use of a fatty acid or alkylamine for surface coating of metal particles is for the following reasons.

In order for the surface coating agent to function as described above, it is necessary that the alkyl group is exposed to the outermost surface of the particles. For this purpose, fatty acids and alkyl amines having carboxyl groups or amino groups that interact with the metal particles are preferred.

Use of a fatty acid or alkylamine having 8 to 20 carbon atoms is for the following reasons.

Generally, steric hindrance to aggregation between particles can be efficiently formed by using a surface coating having an alkyl group having a carbon number of 8 or more. When the number of carbon atoms is 21 or more, the melting point is high and it is difficult to handle. Therefore, in reality, fatty acids and alkyl amines having 8 to 20 carbon atoms are preferable.

Examples of the fatty acid having 8 to 20 carbon atoms include pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, oleic acid, Linoleic acid, linolenic acid, eleostearic acid, nonadecylic acid, arachidic acid, arachidonic acid, hexacosic acid and the like can be used.

Examples of the alkylamine having 8 to 20 carbon atoms include octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, heptadecylamine, octadecylamine, ole Nonadecylamine, icosylamine, and the like can be used.

Of these, fatty acids having 8 to 20 carbon atoms are preferred because they strongly adsorb to the surface of metal particles due to electrostatic interaction, and lauric acid, myristic acid, palmitic acid, stearic acid and oleic acid are preferable Stearic acid and oleic acid are more preferable.

As the metal particles of the component (A), " surface modified metal particles " obtained by reducing a surface of a metal particle surface-coated with a fatty acid having 8 to 20 carbon atoms or an alkylamine having 8 to 20 carbon atoms may be used. Since the oxygen concentration of the surface of the surface-modified metal particles is reduced by the reduction treatment, the contact resistance between the metal particles becomes smaller, and the conductivity of the resulting conductive film is improved.

(B) an aromatic carboxylic acid ester compound

Conventionally, when it is desired to obtain a high bending resistance, a thermoplastic resin such as a polyester resin is used as a binder resin like the conductive paste described in Patent Document 2.

However, when a thermoplastic resin is used as the binder resin as in the case of the conductive paste described in Patent Document 2, there is a problem that scratches are likely to occur and the resin is easily broken.

For this reason, when it is desired to obtain a conductive film which is less liable to be scratched, a thermosetting resin such as phenol resin is used as the binder resin. However, when a thermosetting resin is used as the binder resin, it tends to be difficult to obtain the bending resistance. The reason is that when the cured film of the thermosetting resin is bent, the stress generated between the metal particles and the binder resin becomes large, so that the interface between the metal particles and the binder resin is destroyed and the peeling progresses.

On the other hand, in the conductive paste of the present invention, the interaction of the metal particles and the binder resin in the conductive paste is improved by mixing the ester compound of the aromatic carboxylic acid, which will be described in detail below, as the component (B) The interfacial adhesion force is higher than the stress generated between the binder resin, and the bending resistance of the conductive film is improved. For that reason, the present inventors estimate as follows.

(B), that is, an alkyl group forming an ester bond with an aromatic carboxylic acid, interacts with a fatty acid having 8 to 20 carbon atoms or an alkylamine having 8 to 20 carbon atoms covering the surface of the metal particle of component (A) , And the aromatic carboxylic acid having a benzene ring forms an interaction with the binder resin of component (C). By this interaction, the metal particles can form strong bonds with the binder resin.

As the component (B), an ester compound of an aromatic carboxylic acid selected from the group consisting of benzoic acid, phthalic acid, isophthalic acid and terephthalic acid is used. The reason why benzoic acid, phthalic acid, isophthalic acid or terephthalic acid is used as the aromatic carboxylic acid forming the ester compound is that these compounds are aromatic carboxylic acids having a benzene ring in their structure and have a large volume structure directly bonded to the benzene ring It is easy to interact with the binder resin.

Among them, phthalic acid, which is an aromatic dicarboxylic acid of ortho-coordination, is adjacent to two alkyl chains produced by an ester bond. Therefore, it is considered that the terephthalic acid of the meta-coordination and the terephthalic acid of the para-coordination firmly interact with the alkyl chain on the surface of the metal particle. Further, in the case of the benzoic acid ester, there is a possibility that sufficient interaction is not obtained because the alkyl chain produced by the ester bond is one. For these reasons, phthalic acid is preferable to other aromatic carboxylic acids.

In the component (B), the alkyl group forming the ester bond with the carboxyl group of the aromatic carboxylic acid is an alkyl group having 3 to 20 carbon atoms. In the case of aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid, two alkyl groups forming these ester bonds are present because they have two carboxyl groups. The total carbon number of these two alkyl groups is 40 or less. The two carboxyl groups and the ester-bonded alkyl groups may be the same or different. The alkyl group having 3 to 20 carbon atoms may be either a straight chain structure or a branched structure.

As the component (B), only one kind of the aromatic carboxylic acid ester compound satisfying the above may be used, or two or more kinds thereof may be used in combination.

An aromatic carboxylic acid ester compound having an alkyl group of 21 or more ester-bonded with a carboxyl group of an aromatic carboxylic acid (in the case of an aromatic dicarboxylic acid ester compound, the total number of carbon atoms of the alkyl group ester-bonded to the carboxyl group is 40 or more) It is difficult to ensure sufficient fluidity as a conductive paste even if it is available.

On the other hand, when the number of carbon atoms of the alkyl group ester-bonded to the carboxyl group of the aromatic carboxylic acid is 2 or less, the interaction between the metal particles of the component (A) and the fatty acid having 8 to 20 carbon atoms or the alkylamine having 8 to 20 carbon atoms And the interaction between the metal particles in the conductive paste and the binder resin can not be improved. As a result, the interfacial adhesion can not be exhibited more than the stress generated between the metal particles and the binder resin, and the bending resistance of the conductive film can not be improved.

In the aromatic carboxylic acid ester compound as the component (B), the number of carbon atoms of the alkyl group ester-bonded to the carboxyl group of the aromatic carboxylic acid is preferably 3 to 18, more preferably 3 to 15.

When the component (B) is an aromatic dicarboxylic acid ester compound, the total number of carbon atoms of the alkyl group ester-bonded to the carboxyl group is preferably 36 or less, more preferably 30 or less.

When the component (B) is a benzoic acid ester compound, it is preferable to use a compound selected from the group consisting of octyl benzoate, nonyl benzoate, decyl benzoate, undecyl benzoate, dodecyl benzoate, tridecyl benzoate, tetradecyl benzoate, pentadecyl benzoate, hexadecyl benzoate, Decyl, nonadecyl benzoate, and eicosyl benzoate may be used.

When the component (B) is an isophthalic acid ester compound, it is preferable to use at least one member selected from the group consisting of diphenyl isophthalate, diisopropyl isophthalate, dibutyl isophthalate, diisobutyl isophthalate, dipentyl isophthalate, diisopentyl isophthalate, Diisobutyl phthalate, diisobutyl phthalate, diisobutyl phthalate, diisobutyl phthalate, diisobutyl phthalate, diisobutyl phthalate, diisobutyl phthalate, diisobutyl phthalate, diisobutyl phthalate, diisobutyl phthalate, Diisodecyl isophthalate, diisodecyl isophthalate, diisodecyl isophthalate, diisodecyl isophthalate, isodecyl isophthalate, diisodecyl isophthalate, ditridecyl isophthalate, diisotridecyl isophthalate, ditetradecyl isophthalate, diisotetradecyl isophthalate , Dipentadecyl isophthalate, diisopentadecyl isophthalate, dihexadecyl isophthalate, dihexadecyl isophthalate, diheptafatty acid dihepta Decyl, diheptadecyl isophthalate, dioctadecyl isophthalate, diisoctadecyl isophthalate, dinonadecyl isophthalate, diisononadecyl isophthalate, diacosyl isophthalate, and diisoquecyl isophthalate can be used .

When the component (B) is a terephthalic acid ester compound, it is preferable to use a compound selected from the group consisting of dipropyl terephthalate, diisopropyl terephthalate, dibutyl terephthalate, diisobutyl terephthalate, dipentyl terephthalate, diisopentyl terephthalate, dihexyl terephthalate, diheptyl terephthalate , Diheptyl terephthalate, dioctyl terephthalate, diisooctyl terephthalate, dinonyl terephthalate, diisononyl terephthalate, diisodecyl terephthalate, diisodecyl terephthalate, diundecyl terephthalate, diisonecyl terephthalate, didodecyl terephthalate Diisodecyl terephthalate, diheptadecyl terephthalate, dihexadecyl terephthalate, dihexadecyl terephthalate, diheterodecyl terephthalate, diisodecyl terephthalate, diisodecyl terephthalate, diisodecyl terephthalate, diisotridecyl terephthalate, ditetradecyl terephthalate, diisotetradecyl terephthalate, Hepta Decyl, diheptodecyl terephthalate, dioctadecyl terephthalate, diisoctadecyl terephthalate, dinonadecyl terephthalate, diisononadecyl terephthalate, diacosyl terephthalate, and diisoquecyl terephthalate.

As the component (B), a phthalic acid ester compound represented by the following formula is preferable. This is because the two alkyl chains produced by the ester bond are close to each other, so that they form a strong interaction with the alkyl chain on the metal surface and that the substituent is ortho coordination, so that steric hindrance on the benzene ring side is small, And it is considered that it is easy to interact with the benzene ring in the resin.

In the formula, R and R 'are independently an alkyl group having 3 to 20 carbon atoms provided that the total number of carbon atoms of the alkyl group is 40 or less.

That is, in the phthalic acid ester compound represented by the above formula, the two alkyl groups forming the ester bond with the carboxyl group of the phthalic acid are an alkyl group having 3 to 20 carbon atoms. Here, the alkyl group forming the ester bond with the carboxyl group of the phthalic acid may be the same or different.

The alkyl group having 3 to 20 carbon atoms may be either a straight chain structure or a branched structure.

Examples of the phthalic acid ester compound represented by the above formula include diisopropyl phthalate, diisopropyl phthalate, dibutyl phthalate, diisobutyl phthalate, diisopentyl phthalate, diisopentyl phthalate, dihexyl phthalate, dihexyl phthalate, Diisobutyl phthalate, diheptyl phthalate, dioctyl phthalate, diisooctyl phthalate, diethylhexyl phthalate, dinonyl phthalate, diisononyl phthalate, dodecyl phthalate, diisodecyl phthalate, decyl undecyl phthalate, Dodecyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diisotridecyl phthalate, ditetradecyl phthalate, diisotetradecyl phthalate, dipentadecyl phthalate, diisopentadecyl phthalate, dihexadecyl phthalate , Dihexadecyl phthalate, diheptadecyl phthalate, diheoheptadecyl phthalate, dioctadecyl phthalate, diisooctadecyl phthalate, And the like can be de-dino or decyl phthalate, di-iso-nonadecyl, dieyi kosil acid, phthalic acid diisobutyl eicosyl.

As the component (B), only one of the phthalic acid ester compounds may be used, or two or more kinds thereof may be used in combination.

In the conductive paste of the present invention, the blending amount of the aromatic dicarboxylic acid ester compound as the component (B) is 0.01 to 2.5 parts by mass, preferably 0.02 to 2.0 parts by mass based on 100 parts by mass of the total components of the conductive paste.

When the amount of the aromatic dicarboxylic acid ester compound of the component (B) satisfies the above range, the metal particles in the conductive paste and the binder resin can form an interaction with each other, and the conductive film formed by using the conductive paste has good conductivity And has excellent bending resistance.

If the compounding amount of the aromatic dicarboxylic acid ester compound as the component (B) is less than 0.01 part by mass based on the total 100 parts by mass of the total components of the conductive paste, the amount of the phthalic acid ester compound is insufficient, The resin can not form an appropriate interaction. As a result, the conductivity of the formed conductive film is lowered, and the change (deterioration) in conductivity before and after bending is increased.

On the other hand, when the compounding amount of the aromatic dicarboxylic acid ester compound (B) exceeds 2.5 parts by mass relative to the total 100 parts by mass of the total components of the conductive paste, the phthalic acid ester compound And the conduction between the metal particles is hindered. As a result, it is considered that the conductivity of the conductive film to be formed is lowered.

In the conductive paste of the present invention, the blending amount of the aromatic dicarboxylic acid ester compound as the component (B) is preferably 0.02 to 4.0 parts by mass, more preferably 0.04 to 3.5 parts by mass relative to 100 parts by mass of the metal particles of the component (A) desirable. The reason why the amount is preferably 0.02 parts by mass or more is that when the amount of the binder resin is 0.02 parts by mass or more, the alkyl chain of the component (B) capable of interacting with the alkyl chain on the surface of the metal particles becomes a sufficient amount, Loses.

On the other hand, a content of not more than 4.0 parts by mass is preferable because the aromatic dicarboxylic acid ester compound exists outside the interface between the metal particles and the binder resin, and the hardness of the cured film is lowered.

(C) Binder resin

As described above, in the conductive paste requiring high hardness film hardness, a thermosetting resin is used as the binder resin.

In the conductive paste of the present invention, as the binder resin of the component (C), a thermosetting resin having a benzene ring is used. This is because the presence of the benzene ring in the structure of the thermosetting resin interacts with the benzene ring of the aromatic dicarboxylic acid ester compound of the component (B).

As the thermosetting resin having a benzene ring, phenol resin, cresol resin, epoxy resin, unsaturated polyester resin, xylene resin, polyimide and the like can be used.

As the binder resin of the component (C), a thermosetting resin having a benzene ring and containing formaldehyde as one component is more preferable. This is because a thermosetting resin having a benzene ring and formaldehyde as one component has a large shrinkage upon curing with heating and a strong force for pressing metal particles, so that high conductivity and high film hardness are easily obtained. In addition, particularly when copper fine particles are used as metal particles, the oxidation of the surface of the copper particles can be suppressed by the reducing action of the methylol group generated from formaldehyde, and the curing shrinkage progresses appropriately to secure the contact between the copper particles .

Phenol resin, cresol resin, xylene resin and the like can be used as the thermosetting resin having a benzene ring and containing formaldehyde as one component. Among them, the phenol resin is preferable in terms of the reducing action of the methylol group and the degree of curing shrinkage. If the hardening shrinkage is too large, unnecessary stress accumulates in the conductive film, which causes mechanical breakdown. If the hardening shrinkage is too small, sufficient contact between the metal particles can not be ensured.

In the conductive paste of the present invention, the amount of the binder resin of the component (C) may be properly selected depending on the volume of the metal particles of the component (A) and the ratio of the volume of the void portion existing between the metal particles, Is preferably from 5 to 25 parts by mass, and more preferably from 10 to 20 parts by mass, per 100 parts by mass of the total amount. When the amount is 5 parts by mass or more, the portion where the binder resin and the surface of the metal particle are bonded increases, and the resistance to bending is improved, and the flowability of the conductive paste is improved. When the amount is 25 parts by mass or less, the number of metal parts in the conductor is increased, and sufficient contact between the metal particles can be ensured. Therefore, the conductive film formed using the conductive paste has good conductivity and bending resistance.

In the conductive paste of the present invention, the amount of the binder resin of the component (C) is preferably 15 to 35 parts by mass, more preferably 20 to 30 parts by mass, per 100 parts by mass of the metal particles of the component (A). The reason that 15 parts by mass or more is preferable is because if the amount is 15 parts by mass or more, the amount of the binder resin in the cured film becomes large and the stress at the time of bending can be relaxed, thereby improving the bending resistance.

On the other hand, the reason why 35 parts by mass or less is preferable is because if the amount is less than 35 parts by mass, the conductivity of the cured film is sufficiently obtained.

(D) Other components

The conductive paste of the present invention may contain a solvent and various additives (leveling agent, viscosity adjusting agent, etc.) in addition to the components (A) to (C) . Particularly, in order to obtain a paste having an appropriate fluidity, it is preferable to include a solvent capable of dissolving the thermosetting resin.

As the solvent, there may be mentioned, for example, cyclohexanone, cyclohexanol, terpineol, ethylene glycol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, , Diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether acetate, and diethylene glycol monobutyl ether acetate. As the printing paste, the amount of the solvent to be contained in the conductive paste is preferably 5 to 40 parts by mass per 100 parts by mass of the total components of the conductive paste, from the viewpoint of setting a suitable viscosity range.

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

The temperature for mixing and stirring is preferably 10 to 50 占 폚. More preferably 20 to 30 占 폚. By heating at a temperature of 10 占 폚 or higher when the conductive paste is produced, the viscosity of the paste can be sufficiently lowered, and stirring can be smoothly and sufficiently performed. On the other hand, if the temperature during mixing and stirring exceeds 50 占 폚, the resin may be hardened in the paste, and fusion of the particles may occur. Further, in order to prevent the metal particles from being oxidized at the time of mixing, it is preferable to mix them in a container substituted with an inert gas.

In the conductive paste of the present invention described above, the component (A) is surface-coated with a fatty acid having 8 to 20 carbon atoms or an alkylamine having 8 to 20 carbon atoms and has a volume resistivity of 10 mu OMEGA .cm or less, Since the binder resin containing the aromatic carboxylic acid ester compound as the component (B) and the thermosetting resin having the benzene ring as the component (C) is contained together with the metal particles having the thickness of 15 탆, the conductive film formed by the conductive paste Has a high film hardness, and is also excellent in conductivity, bending resistance, high temperature and high humidity durability.

≪ Substrate with conductive film &

The base material provided with the conductive film of the present invention has a base material and a conductive film formed by applying and curing the above-described conductive paste of the present invention on the base material.

As described above, since the conductive film formed using the conductive paste of the present invention has good conductivity and excellent bending resistance, a flexible film is preferable as the substrate main body. Examples of the flexible film include a plastic substrate (for example, a polyimide substrate and a polyester substrate), and a substrate including a fiber reinforced composite material (for example, a glass fiber reinforced resin substrate).

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

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

The heating temperature and the heating time may be appropriately determined according to the properties required for the conductive film. The heating temperature is preferably 80 to 200 占 폚. If the heating temperature is 80 DEG C or higher, curing of the binder resin progresses smoothly, contact between the metal particles becomes good, and conductivity and durability are improved. If the heating temperature is 200 DEG C or less, the plastic substrate can be used as the base body, and the degree of freedom in substrate selection can be increased.

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

The resistivity (also referred to as volume resistivity) of the conductive film is preferably 50 mu OMEGA .cm or less. If the resistivity of the conductive film exceeds 50 占 cm, it may become difficult to use it as a conductor for electronic devices.

The amount of change (increase) of the resistivity before and after bending (10000 times of bending) measured according to the procedure described in the later-described embodiment is preferably 500% or less, more preferably 300% or less.

The amount of increase (increase) in specific resistance before and after the high temperature and high humidity test, which is measured according to the procedure described in Examples to be described later, is preferably 20% or less, more preferably 10% or less, and particularly preferably 5% or less.

[Example]

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Examples 1 to 7 are Examples, and Example 8 is Comparative Example. In addition, the average particle diameter of the metal particles (copper particles), the thickness of the conductive film, and the resistivity were measured using the apparatuses described below.

(Average particle diameter)

Copper particles were used as metal particles. The copper particles are surface-coated with stearic acid. The particle diameters of the copper particles were determined by measuring the Feret diameters of 100 randomly selected particles in an SEM image obtained by SEM (S-4300, Hitachi Hi-Tech Industries, Ltd.) (Feret diameter in the major axis direction + Feret diameter in the minor axis direction) / 2) of the long axis direction Feret diameter and the minor axis direction Feret diameter (when the direction is the long axis and the axis orthogonal to the long axis is the short axis, . Then, the average value (average particle diameter) of the particle diameters was obtained by averaging (number average) the particle diameters of the calculated copper particles.

(Thickness of the conductive film)

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

(Resistivity of the conductive film)

The specific resistance of the conductive film was measured using a 4-probe volume resistivity meter (manufactured by Mitsubishi Yucca, model: lorestaIP MCP-T250).

Example 1

(Trade name: 1200YP, manufactured by Mitsui Kinzoku Kogyo Kabushiki Kaisha) surface-coated with stearic acid, which is a fatty acid having 8 to 20 carbon atoms, was used as the metal particles of the component (A). Hereinafter, in the present specification, the copper particles are referred to as surface-coated copper particles (A). The surface-coated copper particles (A) have an average particle diameter of 3 占 퐉.

3.0 g of formic acid and 9.0 g of a 50% by mass aqueous solution of hypophosphorous acid were placed in a glass beaker, and the beaker was placed in a water bath and kept at 40 캜. 5.0 g of the surface-coated copper particles (A) was gradually added to the beaker and stirred for 30 minutes to obtain a copper dispersion.

The resulting copper dispersion was centrifuged at a rotation number of 3000 rpm for 10 minutes using a centrifugal separator to recover the precipitate. The precipitate was dispersed in 30 g of distilled water and the precipitate was separated by centrifugation again to precipitate the aggregate. Thereafter, the obtained precipitate was heated under a reduced pressure of -35 kPa at 80 캜 for 60 minutes to remove the residual moisture by volatilization, thereby obtaining the surface-modified surface-coated copper particles (A). The surface-modified surface-coated copper particles are referred to as surface-modified copper particles (A).

The surface-coated copper particles after surface modification have an average value of the particle diameter of 3 mu m without change. It should be noted that the average value of the particle diameters of the surface-coated copper particles after the surface modification does not change is the same for the other examples described below.

12 g of the surface-modified copper particles (A) were dissolved in 3.0 g of ethylene glycol monobutyl ether acetate (2.8 g) as a phenol resin (trade name: IF-3300, And 0.16 g of dibutyl phthalate as the component (B) was added to the mixture together with the mixture, and the mixture was mixed at room temperature to obtain a copper paste. The amount of the component (B) was 0.9 parts by mass based on 100 parts by mass of the total amount of the components of the copper paste, and the amount of the component (C) was 16 parts by mass based on 100 parts by mass of the total components of the copper paste.

Example 2

12 g of the surface-modified copper particles (A) was added to a resin solution obtained by dissolving 2.8 g of a phenol resin as the component (C) in 3.0 g of ethylene glycol monobutyl ether acetate. Further, 0.08 g of dioctyl phthalate as the component (B) was added to the mixture together with the mixture, and the mixture was mixed at room temperature to obtain a copper paste. The amount of the component (B) was 0.4 parts by mass based on 100 parts by mass of the total amount of the components of the copper paste, and the amount of the component (C) was 16 parts by mass based on 100 parts by mass of the total components of the copper paste.

Example 3

12 g of the surface-modified copper particles (A) was added to a resin solution obtained by dissolving 2.8 g of a phenol resin as the component (C) in 3.0 g of ethylene glycol monobutyl ether acetate, together with this mixture, dinonyl phthalate 0.08 g were added to the mortar and mixed at room temperature to obtain a copper paste. The amount of the component (B) was 0.4 parts by mass based on 100 parts by mass of the total of the components of the copper paste, and the amount of the component (C) was 16 parts by mass based on 100 parts by mass of the total components of the copper paste.

Example 4

12 g of the surface-modified copper particles (A) was added to a resin solution obtained by dissolving 2.8 g of a phenol resin as the component (C) in 3.0 g of ethylene glycol monobutyl ether acetate, and further with this mixture, dinonyl phthalate 0.16 g were added to the mortar and mixed at room temperature to obtain a copper paste. The amount of the component (B) was 0.9 parts by mass based on 100 parts by mass of the total amount of the components of the copper paste, and the amount of the component (C) was 16 parts by mass based on 100 parts by mass of the total components of the copper paste.

Example 5

12 g of the surface-modified copper particles (A) was added to a resin solution obtained by dissolving 2.8 g of a phenol resin as the component (C) in 3.0 g of ethylene glycol monobutyl ether acetate, and 0.08 g of diisodecyl phthalate as component (B) g were added to the mortar and mixed at room temperature to obtain a copper paste. The amount of the component (B) was 0.4 parts by mass based on 100 parts by mass of the total of the components of the copper paste, and the amount of the component (C) was 16 parts by mass based on 100 parts by mass of the total components of the copper paste.

Example 6

12 g of the surface-modified copper particles (A) were added to a resin solution obtained by dissolving 2.8 g of a phenol resin as the component (C) in 3.0 g of ethylene glycol monobutyl ether acetate, and 0.08 g of isododecyl phthalate 0.03 g were added to the mortar and mixed at room temperature to obtain a copper paste. The amount of the component (B) was 0.2 parts by mass based on 100 parts by mass of the total amount of the components of the copper paste, and the amount of the component (C) was 16 parts by mass based on 100 parts by mass of the total amount of all components of the copper paste.

Example 7

12 g of the surface-modified copper particles (A) was added to a resin solution obtained by dissolving 2.8 g of a phenol resin as the component (C) in 3.0 g of ethylene glycol monobutyl ether acetate, and with this mixture, Were added to the mortar and mixed at room temperature to obtain a copper paste. The amount of the component (B) was 0.2 parts by mass based on 100 parts by mass of the total amount of the components of the copper paste, and the amount of the component (C) was 16 parts by mass based on 100 parts by mass of the total amount of all components of the copper paste.

Example 8

A copper paste was obtained in the same manner as in Example 1 except that the phthalic acid ester compound (B) was not added to 12 g of the surface-modified copper particles (A) at room temperature.

Then, the copper paste obtained in Examples 1 to 8 was applied onto PET having a thickness of 75 탆, respectively, and heated at 150 캜 for 30 minutes to cure the phenol resin as the component (C) to form a conductive film having a thickness of 15 탆.

Further, the electrical resistance value of the obtained conductive film was measured using a resistance value meter (trade name: Milliohightester, manufactured by KSL), and the specific resistance (volume resistivity; unit μΩ · cm) was measured.

For the bending test of the conductive film, the conductor was bent inward at a bending radius of 5 mm using a commercially available bending tester (product name: TCDM111LH, manufactured by Yuasa Kogyo Kikai Co., Ltd.), and then bending outwardly was repeated 10,000 times to change the resistivity Were measured.

The substrates having the conductive films of Examples 3 and 8 were subjected to a durability test under an environment of high temperature and high humidity. That is, the base material provided with the conductive film was maintained at a high temperature and high humidity of 85 ° C and 85% RH for 240 hours in a tank, and then the amount of change in specific resistance was measured. 1 is a graph showing the relationship between the high temperature and high humidity test time and the change amount of resistivity for Examples 3 and 8.

As can be seen from Table 1, the phthalic acid ester compound represented by the above formula as the component (B), together with the copper particles having an average particle diameter of 0.5 to 15 占 퐉 surface-coated with stearic acid, The conductive paste obtained by coating the conductive paste on the base material and curing the conductive paste had a low resistivity of 50 μ? · Cm or less by using the conductive paste of Examples 1 to 7 in which 0.01 to 2.5 mass parts were combined with 100 parts by mass of the total of 100 parts by mass. Further, the change (increase) of the resistivity before and after bending was also suppressed.

On the other hand, in Example 8 in which the phthalic acid ester compound of component (B) was not blended, the conductive film produced using the conductive paste had a large change (increase) in specific resistance due to bending.

As can be seen from Fig. 1, Example 3 in which dinonyl phthalate was incorporated showed lower change in specific resistance under a high temperature and high humidity environment than Example 8 in which the phthalic acid ester compound (B) was not blended, It was excellent.

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

The present application is based on Japanese Patent Application No. 2014-002534 filed on January 9, 2014, the contents of which are incorporated herein by reference.

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

Claims (7)

(A) an aromatic carboxylic acid ester compound selected from the group consisting of benzoic acid, phthalic acid, isophthalic acid and terephthalic acid and (B) metal particles having a volume resistivity of 10 mu OMEGA .cm or less and an average particle size of 0.5 to 15 mu m Provided that the total number of carbon atoms of the alkyl group is 40 or less when the number of the alkyl groups forming the ester bond is 40 or less); (C) a thermosetting resin having a benzene ring Wherein the metal particles of the component (A) are surface coated with a fatty acid having 8 to 20 carbon atoms, and the total amount of the component (C) is 100 parts by mass based on 100 parts by mass of the total components of the conductive paste, (B) is contained in an amount of from 5 to 25 parts by mass and the aromatic carboxylic acid ester compound (B) is contained in an amount of from 0.01 to 2.5 parts by mass Conductive paste. The conductive paste according to claim 1, wherein the metal particles of the component (A) are copper particles or silver particles having an average particle diameter of 0.5 to 15 占 퐉. The phthalic ester compound represented by the formula (ROOC) -C ₆ H ₄ - (COOR ') (wherein R and R' are as defined above), wherein the aromatic carboxylic acid ester compound (B) Is an alkyl group having 3 to 20 carbon atoms independently of each other provided that the total number of carbon atoms of the alkyl group is 40 or less. 4. The composition of claim 3 wherein the phthalic acid ester compound is selected from the group consisting of diphenyl phthalate, diisopropyl phthalate, dibutyl phthalate, diisobutyl phthalate, dipentyl phthalate, diisopentyl phthalate, dihexyl phthalate, diheptyl phthalate, , Diheptyl phthalate, dioctyl phthalate, dihexyl octyl phthalate, diethylhexyl phthalate, diethylhexyl phthalate, dinonyl phthalate, diisononyl phthalate, didecyl phthalate, diisodecyl phthalate, decyl undecyl phthalate, phthalic acid di Isodecyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diisotridecyl phthalate, ditetradecyl phthalate, diisotetradecyl phthalate, dipentadecyl phthalate, diisopentadecyl phthalate, dihexadecyl phthalate, Decyl phthalate, dihexadecyl phthalate, diheptadecyl phthalate, diheoheptadecyl phthalate, dioctadecyl phthalate, diisoctadecyl phthalate, phthalic acid dino Decyl phthalate, di-iso-nonadecyl, dieyi kosil acid, phthalic acid di least one member, the conductive paste is selected from the group consisting of iso-eicosyl chamber. The positive resist composition according to any one of claims 1 to 4, wherein the binder resin of component (C) is at least one selected from the group consisting of phenol resin, cresol resin, epoxy resin, unsaturated polyester resin, xylene resin, and polyimide Conductive paste. A substrate comprising a conductive film formed on a substrate, the conductive film being formed by applying the conductive paste according to any one of claims 1 to 5 and curing the conductive paste. The substrate according to claim 6, wherein the substrate is a flexible film.

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