KR101568056B1 - Conductive paste and conductive circuit - Google Patents

Abstract

The present invention provides a conductive paste capable of forming a low-resistance conductive circuit. The present invention also provides a conductive paste having photosensitivity and capable of achieving the above characteristics while achieving high resolution of the conductive circuit.
The conductive paste according to the present embodiment is characterized by containing at least one of conductive powder, organic binder, and derivatives of thiodiglycolic acid and thiodiglycolic acid.

Description

CONDUCTIVE PASTE AND CONDUCTIVE CIRCUIT [0002]

The present invention relates to a conductive paste and a conductive circuit using the conductive paste.

BACKGROUND ART Conventionally, as a technique for forming a conductive circuit for a flat panel display (hereinafter also referred to as " FPD ") such as a plasma display panel (hereinafter also referred to as a" PDP "), a conductive paste A pattern is formed on a substrate by a printing technique such as screen printing or by a photolithography technique using a photosensitive paste imparted with photosensitivity and then firing is performed at 550 DEG C or higher, And simultaneously fusing the conductive powder onto the substrate to form a conductive circuit composed only of an inorganic component (see, for example, Patent Documents 1 and 2). However, since this method is carried out at a very high temperature condition, applicable substrates are limited.

On the other hand, as a technology for forming a conductive circuit for a flexible device such as an electronic paper using PET or the like and a device having low heat resistance such as a touch panel, a conductive paste is patterned on a substrate, To thereby form a conductive circuit including the conductive powder and the organic component (see, for example, Patent Document 3, etc.).

In order to obtain high conductivity in the conductive circuit formed by these conductive pastes, for example, the content of the conductive powder in the conductive paste is increased or a shape such as a flaky conductive powder is specified, There is an upsurge, but there is still room for improvement because it is not enough.

On the other hand, demand for miniaturization, high density and high precision in multilayer circuit boards or FPDs such as PDPs for mounting a large number of highly integrated LSIs and various electronic components is increasing, Is more demanded.

With respect to such a demand, a photolithography method which is capable of achieving high precision of a conductive circuit in comparison with a screen printing method is preferable. In the photolithography method, however, the conductive powder hardly sufficiently hardens to the inside (deep portion) There is a problem in that diffusion of the radicals or active species generated in the reaction proceeds and the resolution of the conductive circuit is deteriorated.

Japanese Patent Application Laid-Open (kokai) No. 10-269848 (claims) Japanese Patent No. 3520798 Japanese Patent Application Laid-Open No. 2004-355933 (claims)

An object of the present invention is to provide a conductive paste capable of forming a low-resistance conductive circuit. Another object of the present invention is to provide a conductive paste having photosensitivity imparted thereto and capable of achieving high resolution of the conductive circuit while achieving the above characteristics.

The conductive paste according to the present embodiment is characterized by containing at least one of conductive powder, organic binder, and derivatives of thiodiglycolic acid and thiodiglycolic acid. With this configuration, the resistance of the conductive circuit can be reduced. Particularly, in a conductive circuit which does not burn out the organic component, a low resistance which can not be achieved conventionally can be achieved.

In a preferred embodiment of the conductive paste according to the present embodiment, the conductive powder is preferably a silver powder. It is preferable that the conductive paste according to the present embodiment contains at least one of the thiodiglycolic acid and the thiodiglycolic acid derivative as solid content in an amount of 0.01 to 10 parts by mass per 100 parts by mass of the organic binder resin. With this configuration, it is possible to further reduce the resistance of the conductive circuit.

Further, the conductive paste according to the present embodiment is characterized in that it further contains a photopolymerizable monomer and an oxime ester-based photopolymerization initiator. With such a configuration, it is possible to achieve a low resistance of the obtained conductive circuit and to attain high resolution.

Further, the conductive circuit according to the present embodiment is characterized by being formed using the conductive paste described above.

According to the conductive paste of the present invention, a low-resistance conductive circuit can be formed. In addition, in the conductive paste imparted with photosensitivity, it is possible to achieve the above characteristics while attaining high resolution of the conductive circuit.

The inventors of the present invention have made intensive investigations on the above problems and have found that by containing at least any one of conductive powder, organic binder and derivatives of thiodiglycolic acid and thiodiglycolic acid in a paste used for forming a conductive circuit, , And finding that the obtained conductive circuit can attain high resistance as well as low resistance by containing an oxime ester photopolymerization initiator as a photopolymerization initiator when the paste is given photosensitivity The present invention has been completed.

Hereinafter, the conductive paste of this embodiment will be described in detail.

The conductive powder in the conductive paste of the present embodiment imparts conductivity to the conductive circuit formed. Specifically, the conductive powder is made of Ag, Au, Pt, Pd, Ni, Cu, Al, Sn, Pb, Fe, Ir, Os, Rh, W, Mo, and Ru. These conductive powders may be used in the form of a single body, or any of these alloys, or a multi-layered body in which any one of them is a core or a coating layer. An oxide such as tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), or ITO (indium tin oxide) may also be used. Among these conductive powders, Ag is preferably used.

As the shape of the conductive powder, various shapes such as a sphere shape, a flake (scaly) phase, and a dendritic shape can be used, and there is no particular limitation.

The particle diameter of the conductive powder is not particularly limited. For example, when a spherical conductive powder is used, the average particle diameter is 0.1 to 5 mu m, preferably 0.2 to 3 mu m. When a conductive powder on a flake is used, the average particle diameter is 0.1 to 5 mu m, preferably 0.3 to 3 mu m.

The average particle diameter is determined by measuring 10 random conductive powders observed using an SEM (scanning electron microscope) and calculating the average.

In addition, the flake refers to a powder having an aspect ratio of 3 or more. The aspect ratio can be obtained by (average particle diameter / average thickness T).

Here, "average particle diameter" represents an average long diameter L of 10 particles measured in the longitudinal direction by a scanning electron microscope, and "average thickness T" represents an average thickness T of 10 particles measured in the thickness direction by a scanning electron microscope .

The conductive powder is preferably 30 to 90% by mass based on the nonvolatile component of the conductive paste (the component remaining in the film without volatilization from the paste in the drying step). When it is less than 30 mass%, it becomes difficult to obtain sufficient conductivity. When it exceeds 90 mass%, printing property is deteriorated and it becomes difficult to form a film. Further, when the conductive paste is photosensitive, the light at the time of exposure does not transmit to the deep portion of the coating film, so that the photocurability of the deep portion deteriorates, making it impossible to form a thin line pattern. More preferably 50 to 85% by mass.

The organic binder in the conductive paste of the present embodiment is used for forming a pattern on a coating film by dispersing the conductive powder in a state capable of being applied onto the substrate and developing the conductive paste by pattern exposure when the conductive paste is photosensitive .

As the organic binder, any of a non-photosensitive resin and a photosensitive resin can be used. As the organic binder, any one of a dry organic binder, a thermoset organic binder, and a photo-curable organic binder may be used. It is not necessarily used as a group, but two or more types may be used in combination.

Among them, the drying organic binder and the thermosetting organic binder are used for the non-photosensitive conductive paste. Drying The organic binder is used together with an organic solvent to be described later, and the organic solvent is removed by heating and drying to form a dry film. The thermosetting organic binder is cured by intermolecular crosslinking under the action of heat or catalyst to form a cured coating film.

Examples of such dry organic binders and thermosetting organic binders include olefinic hydroxyl group-containing polymers such as acrylic polyols, polyvinyl alcohol, polyvinyl acetal, styrene-allyl alcohol resins and phenol resins, and organic polymers such as methylcellulose, ethylcellulose, hydroxyethylcellulose And resins such as ethylene-vinyl acetate copolymer, alkyd resin, alkyd phenol resin, butyral resin, epoxy resin, modified epoxy resin, acrylic resin, polyurethane resin and polyester resin can be used. In particular, when a cured coating film is formed by thermosetting as the thermosetting organic binder, it is preferable to use a thermal polymerization catalyst of a peroxide to be described later in combination.

Further, the photocurable organic binder is used in the case of imparting photosensitivity, and is cured by intermolecular crosslinking under the action of active energy rays such as ultraviolet rays and electron beams to form a cured coating film.

Examples of such photocurable organic binders include resins having a photosensitive group such as an ethylenically unsaturated bond such as a vinyl group, an allyl group, an acryloyl group or a methacryloyl group, or a propargyl group, for example, a resin having an ethylenic unsaturated group Various known photosensitive resins (photosensitive prepolymers) such as a copolymer, a resin obtained by adding an unsaturated carboxylic acid-modified epoxy resin or a polybasic acid anhydride thereto, and the like can be used.

These photocurable organic binders can be used in combination with a compound having at least one ethylenic unsaturated bond in the molecule, that is, in combination with a photopolymerizable monomer described later. The photocurable organic binder is preferably used in combination with a photopolymerization initiator to be described later in order to further promote the photopolymerization.

When the resin is used in the photolithography method, a resin having a carboxyl group is particularly preferable from the viewpoint of developability. Specific examples of such a resin having a carboxyl group (which may be an oligomer or a polymer) include the following.

(1) A carboxyl group-containing resin obtained by copolymerizing an unsaturated carboxylic acid such as (meth) acrylic acid with a compound having an unsaturated double bond such as methyl (meth) acrylate.

(Meth) acrylate, (meth) acrylic acid chloride or the like to a copolymer of an unsaturated carboxylic acid such as (meth) acrylic acid and a compound having an unsaturated double bond such as methyl (meth) A carboxyl group-containing photosensitive resin obtained by adding an unsaturated group as a pendant.

(3) To a copolymer of a compound having an unsaturated double bond with an epoxy group such as glycidyl (meth) acrylate and a compound having an unsaturated double bond such as methyl (meth) acrylate, an unsaturated carboxyl group such as (meth) And reacting the resultant secondary hydroxyl group with a polybasic acid anhydride such as tetrahydrophthalic anhydride.

(4) a compound having a hydroxyl group and an unsaturated double bond such as 2-hydroxyethyl (meth) acrylate in a copolymer of an acid anhydride having an unsaturated double bond such as maleic anhydride and a compound having an unsaturated double bond such as styrene To obtain a carboxyl group-containing photosensitive resin.

(5) A carboxyl group-containing photosensitive resin obtained by reacting a polyfunctional epoxy compound with an unsaturated carboxylic acid such as (meth) acrylic acid, and reacting the produced secondary hydroxyl group with a polybasic acid anhydride such as tetrahydrophthalic anhydride.

(6) An organic acid having one carboxyl group per molecule and no ethylenic unsaturated bond in the epoxy group of a copolymer of a compound having an unsaturated double bond such as methyl (meth) acrylate and glycidyl (meth) acrylate is reacted And reacting the produced secondary hydroxyl group with a polybasic acid anhydride.

(7) A carboxyl group-containing resin obtained by reacting a hydroxyl group-containing polymer such as polyvinyl alcohol with a polybasic acid anhydride.

(8) A compound having an epoxy group and an unsaturated double bond such as glycidyl (meth) acrylate is further reacted with a carboxyl group-containing resin obtained by reacting a hydroxyl group-containing polymer such as polyvinyl alcohol with a polybasic acid anhydride such as tetrahydrophthalic anhydride To obtain a carboxyl group-containing photosensitive resin.

Among them, resins of (1), (2), (3) and (6) are particularly preferably used. These resins may be used alone or in combination. In the present specification, (meth) acrylate is generically referred to as acrylate, methacrylate and a mixture thereof, and the same applies to other similar expressions.

The blending amount of the resin having such a carboxyl group is preferably 1 to 50% by mass based on the nonvolatile component (the component remaining in the film without volatilization in the paste in the drying step). If it is less than 1% by mass, the developability is greatly deteriorated due to the lack of these resins in the formed coating film, and patterning due to development becomes difficult. On the other hand, if it exceeds 50% by mass, the ratio of the conductive powder tends to be insufficient, and the resistance value tends to deteriorate.

The weight average molecular weight is preferably 1,000 to 100,000. When the weight average molecular weight is less than 1,000, the adhesion of the coating film at the time of development deteriorates. On the other hand, when the weight average molecular weight exceeds 100,000, defective development tends to occur. And more preferably from 5,000 to 70,000. In addition, the weight average molecular weight is a value in terms of polystyrene measured by gel permeation chromatography (GPC).

The acid value of the resin having a carboxyl group is preferably 50 to 250 mgKOH / g. When the acid value is less than 50 mgKOH / g, the solubility in an aqueous alkali solution is insufficient, and development defects tend to occur. On the other hand, when the acid value is more than 250 mgKOH / g, deterioration of the adhesion of the coating film, Dissolution occurs.

The double bond equivalent of the carboxyl group-containing photosensitive resin is preferably 350 to 2,000 g / eq. When the double bond equivalent of the carboxyl group-containing photosensitive resin is less than 350 g / eq, the pattern tends to become thick and the sharpness of the line tends to deteriorate. On the other hand, when it exceeds 2,000 g / eq, the working margin during development is narrow, and a high exposure dose is required for photo-curing. More preferably 400 to 1,500 g / eq.

Thiodiglycolic acid is added for imparting stability of a metal plating solution. In this embodiment mode, formation of a low-resistance conductive circuit can be achieved by containing it in a conductive paste used for forming a conductive circuit. In addition, in the case of imparting photosensitivity to the conductive paste, it is possible to attain high resolution as well as low resistance of the conductive circuit by using it in combination with the oxime ester-based photopolymerization initiator described later. As thiodiglycolic acid, for example, thiodiglycolic acid such as CICA (Chemicals, Industrial products, Collect, Associate) grade 1 manufactured by KANTO CHEMICAL Co., Ltd. can be used.

The conductive circuit described above can also be formed by using a derivative of thiodiglycolic acid. A derivative is a compound produced by a small structural change of a compound, and generally refers to a compound in which a hydrogen atom or a specific atomic group in the compound is substituted by another atom or atomic group.

Examples of derivatives of thiodiglycolic acid include 3,3'-thiodipropionic acid, diallyl thiodiacetic acid, thiobis (butyl acetate), disodium thiodiglycolate, 2,2'-thiodiacetic acid bis 2-ethylhexyl), dioctyl thioacetate, 2,2'-thiobis (methyl acetate), and dipotassium thiodiglycolate.

The mixing ratio of at least one of thiodiglycolic acid and derivatives of thiodiglycolic acid is preferably 0.01 to 10 parts by mass per 100 parts by mass of the organic binder in terms of solid content. If it is less than 0.01 part by mass, the conductivity is deteriorated. On the other hand, when the amount is more than 10 parts by mass, the patternability is deteriorated due to the characteristics of at least one of thiodiglycolic acid and thiodiglycolic acid derivatives, which are likewise inferior in conductivity and highly developable. More preferably 0.1 to 5 parts by mass.

In the case of imparting photosensitivity to the conductive paste of the present embodiment, a photopolymerizable monomer may be used.

Examples of the photopolymerizable monomer include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, polyurethane diacrylate , Trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane ethylene oxide modified triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, Each methacrylate corresponding to acrylate; Mono-, di-, tri- or higher polyesters of polybasic acids such as phthalic acid, adipic acid, maleic acid, itaconic acid, succinic acid, trimellitic acid and terephthalic acid with hydroxyalkyl (meth) .

These photopolymerizable monomers may be used alone or in combination of two or more. Among these photopolymerizable monomers, multifunctional monomers having two or more acryloyl groups or methacryloyl groups in one molecule are preferable.

The blending amount of the photopolymerizable monomer is preferably 5 to 200 parts by mass per 100 parts by mass of the organic binder as a solid content conversion.

A photopolymerization initiator may be used for the purpose of promoting photo-curing in the case of imparting photosensitivity to the conductive paste.

Examples of the photopolymerization initiator include benzoin and benzoin alkyl ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin isopropyl ether; Acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone and 1,1-dichloroacetophenone; 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane- Amino acetophenones such as 1,2- (dimethylamino) -2 - [(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone; Anthraquinones such as 2-methyl anthraquinone, 2-ethyl anthraquinone, 2-t-butyl anthraquinone, and 1-chloro anthraquinone; Thioxanthones such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone and 2,4-diisopropylthioxanthone; Ketal such as acetophenone dimethyl ketal and benzyl dimethyl ketal; Benzophenones such as benzophenone; Or xanthones; (2,6-dimethoxybenzoyl) -2,4,4-pentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide Phosphine oxides such as methyl ethyl ketone, ethyl 2,4,6-trimethylbenzoyl diphenyl phosphinate, and the like; And various peroxides.

Examples of commercially available products include IRGACURE 184, Irgacure 819, Irgacure 907, Irgacure 369, Irgacure 379, Irgacure 389, and Lucirin (registered trademark) manufactured by BASF Japan. ) TPO and the like.

The blending amount of the photopolymerization initiator is preferably 0.01 to 50 parts by mass per 100 parts by mass of the organic binder as a solid content conversion. When the amount is less than 0.01 part by mass, the photocurability is insufficient, and the pattern is liable to be deviated. Also, the surface hardening property is insufficient, and the surface of the coating film is damaged at the time of development, which affects the conductivity. On the other hand, if it exceeds 50 parts by mass, halation of the pattern occurs and the sharpness of the pattern end portion is deteriorated. Furthermore, the pattern is less likely to be drawn out, and a pattern having a small space can not be drawn.

Among the photopolymerization initiators, especially oxime ester photopolymerization initiators, since the photoresist has a high light sensitivity, it is possible to sufficiently perform photo-curing with a small amount of exposure even with a paste containing a large amount of conductive powder, and a conductive circuit with high resolution can be formed.

As the oxime ester-based photopolymerization initiator, for example, a compound having a group represented by the following formula (I)

(Wherein R ¹ represents a hydrogen atom, a phenyl group (an alkyl group having 1 to 6 carbon atoms, a phenyl group or a halogen atom), an alkyl group having 1 to 20 carbon atoms (which may be substituted with at least one hydroxyl group, A cycloalkyl group having 5 to 8 carbon atoms, an alkanoyl group having 2 to 20 carbon atoms, or a benzoyl group (which may be substituted with an alkyl group having 1 to 6 carbon atoms or a phenyl group) R ² represents a phenyl group (an alkyl group having 1 to 6 carbon atoms, a phenyl group or a halogen atom), an alkyl group having 1 to 20 carbon atoms (which may be substituted with at least one hydroxyl group, A cycloalkyl group having 5 to 8 carbon atoms, an alkanoyl group having 2 to 20 carbon atoms, or a benzoyl group (which may be substituted with an alkyl group having 1 to 6 carbon atoms or a phenyl group)

2- (acetyloxyiminomethyl) thioxanthen-9-one represented by the following formula (II)

A compound represented by the following formula (III)

(Wherein R ³ and R ⁴ each independently represent an alkyl group having 1 to 12 carbon atoms, M represents S, O or NH, and R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁹ are each independently A hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and m and n represent an integer of 0 to 5)

A compound represented by the following formula (IV)

(Wherein R ¹⁰ represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyclopentyl group, a cyclohexyl group, a phenyl group, a benzyl group, a benzoyl group, an alkanoyl group having 2 to 12 carbon atoms, An alkoxycarbonyl group (when the number of carbon atoms of the alkyl group constituting the alkoxyl group is 2 or more, the alkyl group may be substituted with at least one hydroxyl group, may have at least one oxygen atom in the middle of the alkyl chain), or phenoxycarbonyl group , R ¹¹ and R ¹³ are each independently a phenyl group (which may be substituted with an alkyl group having 1 to 6 carbon atoms, a phenyl group or a halogen atom), an alkyl group having 1 to 20 carbon atoms (which may be substituted with at least one hydroxyl group, , A cycloalkyl group having 5 to 8 carbon atoms, an alkanoyl group having 2 to 20 carbon atoms, or a benzoyl group (an alkyl group having 1 to 6 carbon atoms or a phenyl group having 1 to 6 carbon atoms) Represents May hwandoel), R ¹² may be substituted with a hydrogen atom, a phenyl group (alkyl group having 1 to 6 carbon atoms, a phenyl group or a halogen atom may be substituted), a hydroxyl group (at least one C 1 -C 20 alkyl A cycloalkyl group having 5 to 8 carbon atoms, an alkanoyl group having 2 to 20 carbon atoms, or a benzoyl group (which may be substituted with an alkyl group having 1 to 6 carbon atoms or a phenyl group) Lt; / RTI >

A compound represented by the following formula (V)

(Wherein, R ¹⁴ is C 1 -C 20 alkyl group, having 6 to 30 carbon atoms of the aryl group, aryl alkyl group or a CN with a carbon number of 7 to 30, an alkyl group, an aryl group and a hydrogen atom of the arylalkyl group is added by OR ^{41, COR 41, SR 41, NR 42} R 43, -NCOR 42 -OCOR 43, CN, halogen atom, -CR ⁴¹ = CR ⁴² R ⁴³ or CO-CR ⁴¹ = CR ⁴² with R ⁴³ may be substituted, R ^41, R ⁴² and R ⁴³ each independently represents a hydrogen atom, a heterocyclic group having 1 to 20 carbon alkyl group, having 6 to 30 carbon atoms of the aryl group, having 7 to 30 arylalkyl group or 2 to 20 carbon atoms of, R ¹⁵ is R ⁵¹ Or OR ⁵¹ , R ⁵¹ represents an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms or an arylalkyl group having 7 to 30 carbon atoms, and the hydrogen atom of the alkyl group, aryl group or arylalkyl group is further substituted with a halogen atom may be, R ¹⁶ is an alkyl group having 1 to 20 carbon atoms, having 6 to 30 carbon atoms An aryl group, or an aryl alkyl group having 7 to ^{30, R 14, R 16,} R 41, R 42 and R ⁴³ alkylene methylene group unsaturation of the portion of the substituent represented by the ether bond, a thioether bond, an ester bond , Thioester bond, amide bond or urethane bond, the alkyl portion of the substituent may be branched side chain, may be cyclic alkyl, and the alkyl terminus of the substituent may be an unsaturated bond , R ¹⁶ is a single ring and a benzene adjacent may form a ring. R ¹⁷ and R ¹⁸ is independently R ^51, oR ^51, represents a CN or a halogen atom, a and b are independently 0 to 3, respectively being),

A compound having a carbazol dimer represented by the following formula (VI) can be used.

(Wherein R ¹⁹ represents a hydrogen atom, an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a phenyl group, a phenyl group (an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, An alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group having an alkyl group having 1 to 8 carbon atoms, or a dialkylamino group having a dialkylamino group having a carbon number of 1 to 8) R ²⁰ and R ²¹ each represent a hydrogen atom, an alkyl group having 1 to 17 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a halogen group, a phenyl group, a phenyl group (an alkyl group having 1 to 17 carbon atoms, An alkyl group having 1 to 8 carbon atoms, an amino group, an alkylamino group having an alkyl group having 1 to 8 carbon atoms or a dialkylamino group), a naphthyl group (an alkyl group having 1 to 17 carbon atoms, An alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, an amino group, an alkylamino group having an alkyl group having 1 to 8 carbon atoms or a dialkylamino group), anthryl group, pyridyl group, benzofuryl group and benzothienyl group, 1 to 10 alkylene, vinylene, phenylene, biphenylene, pyridylene, naphthylene, anthrylene, thienylene, furylene, 2,5-pyrrole-diyl, 4,4'- , 4,2'-styrene-diyl, and n is 0 or an integer of 1)

As a commercial product, for example, CGI-325, Irgacure (registered trademark) OXE01, Irgacure OXE02, and NCI-831 manufactured by ADEKA may be used.

The blending amount of the oxime ester-based photopolymerization initiator is preferably 0.01 to 30 parts by mass per 100 parts by mass of the organic binder in terms of solid content. If the amount is less than 0.01 part by mass, the photocuring property becomes insufficient as in the case of the photopolymerization initiator described above, and defects tend to occur in the pattern. Also, the surface hardening property is insufficient and the surface of the coating film is damaged at the time of development, and the resistance value is deteriorated. On the other hand, if it exceeds 30 parts by mass, halation of the pattern occurs similarly to the photopolymerization initiator described above, and the sharpness of the pattern end portion is deteriorated. Furthermore, the pattern is less likely to be drawn out, and a pattern having a small space can not be drawn. More preferably 0.05 to 5 parts by mass.

Examples of the photopolymerization initiator include, but are not limited to, tertiary amines such as N, N-dimethylaminobenzoic acid ethyl ester, N, N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, triethanolamine, Sensitizers, and sensitizers in combination with two or more of them.

Further, for the purpose of accelerating the curing of the conductive paste, a thermal polymerization catalyst may be used if necessary. The thermal polymerization catalyst can be reacted with an uncured polymerizable component by aging at a high temperature of a few minutes to about 1 hour.

Examples of such a thermal polymerization catalyst include peroxides such as benzoyl peroxide and azo compounds such as isobutyronitrile, preferably 2,2'-azobisisobutyronitrile, 2,2'-azobis-2 -Methylbutyronitrile, 2,2'-azobis-2,4-divalvalonitrile, 1,1'-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azobisisobutylate , 4,4'-azobis-4-cyanovaleric acid, 2-methyl-2,2'-azobispropanenitrile, 2,4-dimethyl-2,2,2 ' Nitrile, 1,1'-azobis (1-acetoxy-1-phenylethane), 2,2,2 ', 2'-azobis (2-methylbutanamide oxime) dihydrochloride and the like.

An organic solvent may be used for the conductive paste of this embodiment to adjust the viscosity and to form a uniform coating film.

Examples of such an organic solvent include ketones such as methyl ethyl ketone and cyclohexanone; Aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; Glycol ethers such as cellosolve, methyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether and triethylene glycol monoethyl ether ; Butyl acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, etc. Esters; Alcohols such as ethanol, propanol, ethylene glycol, propylene glycol and terpineol; Aliphatic hydrocarbons such as octane and decane; Petroleum ether such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha and solvent naphtha. These solvents may be used singly or in combination of two or more kinds.

In such a conductive paste, a stabilizer may be further added to improve the storage stability and to suppress deterioration of the coating workability due to gelation or deterioration of fluidity.

As such a stabilizer, a compound having an effect such as complexation with a conductive powder or salt formation in a conductive paste can be used.

Specifically, various inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, and boric acid; Various organic acids such as formic acid, acetic acid, acetoacetic acid, citric acid, stearic acid, maleic acid, fumaric acid, phthalic acid, benzenesulfonic acid and sulfamic acid; (2-methacryloyloxyethyl) acid phosphate, mono (2-methacryloyloxyethyl) acid phosphate, di (2-methacryloyloxyethyl) ethyl phosphate, phosphoric acid, phosphorous acid, hypophosphorous acid, methyl phosphate, ) And various phosphate compounds (inorganic phosphoric acid, organic phosphoric acid) such as acid phosphate. These stabilizers may be used alone or in combination of two or more.

The conductive paste of the present embodiment may contain other additives such as a vesicle / leveling agent such as a silicone type or an acrylic type, or a silane coupling agent for improving the adhesion of a coating film. In addition, known antioxidants and thermal polymerization inhibitors for improving thermal stability during storage may also be added.

The conductive paste constituted as described above is produced by mixing the respective components, and after agitation with a stirrer or the like, the paste can be softened by three-roll milling or the like.

In the case of the non-photosensitive conductive paste, the conductive paste thus produced is printed by printing a desired conductive circuit on a substrate such as a glass substrate by a printing method such as screen printing or offset printing, Is dried or cured at 80 to 300 DEG C for 5 to 60 minutes to form a desired conductive circuit on the substrate.

On the other hand, in the case of a photosensitive conductive paste, a conductive circuit is formed by the following method in addition to the above method.

First, a suitable coating method such as screen printing, bar coater or blade coater is applied to a substrate such as a glass substrate to form a coated film.

Subsequently, the obtained coating film is dried at about 70 to 120 DEG C for about 5 to about 40 minutes in a hot-air circulation type drying furnace, a far-infrared ray drying furnace or the like to obtain a touch-free coating film (dry coating film). At this time, if a conductive paste is formed on a film in advance, it may be laminated on a substrate.

Thereafter, the obtained dry film is subjected to selective exposure. As selective exposure, contact exposure using a negative mask having a predetermined exposure pattern and non-contact exposure can be performed. As the exposure light source, for example, a halogen lamp, a high-pressure mercury lamp, a laser beam, a metal halide lamp, a black lamp, an electrodeless lamp and the like are used. The exposure dose is preferably about 10 to 700 mJ / cm 2.

Development is performed on the coated film after selective exposure. For the development, a spray method, a dipping method, or the like is used. As the developer, the carboxyl group contained in the organic binder contained in the conductive paste may be saponified to remove the uncured portions (unexposed portions). For example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate and the like Metal alkaline aqueous solutions, amine aqueous solutions such as monoethanolamine, diethanolamine, triethanolamine and the like, especially aqueous alkaline solutions having a concentration of about 1.5% by weight or less are preferably used. In addition, it is preferable to conduct the acid or acid neutralization to remove unnecessary developer after the development.

Thereafter, the desired conductive circuit is formed on the substrate by drying or curing the substrate on which the desired conductive pattern is formed by development at 80 to 300 DEG C for 5 to 60 minutes.

[Example]

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following, "%" is based on the entire weight unless otherwise specified.

≪ Synthesis Example of Organic Binder Resin Solution >

A flask equipped with a thermometer, a stirrer, a dropping funnel and a reflux condenser was charged with methyl methacrylate and methacrylic acid in a molar ratio of 0.87: 0.13, and dipropylene glycol monomethyl ether as a solvent and azobisisobutyronitrile as a catalyst And the mixture was stirred at 80 DEG C for 2 to 6 hours in a nitrogen atmosphere to obtain a resin solution containing an organic binder. The organic binder had a weight average molecular weight of about 10,000, an acid value of 74 mgKOH / g, and a solid content of 57%.

The measurement of the weight average molecular weight of the organic binder was carried out in the same manner as in Example 1 except that three pumps, namely, a pump LC-6AD manufactured by Shimadzu Corporation and a column Shodex (registered trademark) KF-804, KF-803 and KF- Liquid chromatography was used.

[Conductive paste]

≪ Production of conductive paste >

The components were mixed with each other in the composition ratios shown in Table 1 and stirred with a stirrer. The mixture was kneaded by a three-roll mill and pasted to prepare conductive pastes of Examples 1 to 3 and Comparative Examples 1 to 4.

<Evaluation of Specific Resistance Value>

Each conductive paste thus prepared was pattern-printed on a glass substrate to form a pattern of 0.4 cm x 10 cm, and heat-treated at 170 deg. C for 30 minutes to form a conductive circuit of 0.4 cm x 10 cm. For this conductive circuit, a sheet resistance value was measured by a division method using a Milli-Ohm Hi Tester, and a specific resistance value was calculated.

* 1: average particle diameter = 1.5 占 퐉

* 2: 2,2'-thiodiglycolic acid (manufactured by Kanto Chemical Co., Ltd .; standard CICA grade 1)

* 3: 3,3'-thiodipropionic acid (manufactured by Kanto Kagaku Co., Ltd., standard CICA grade 1)

* 4: Glycolic acid (manufactured by Kanto Kagaku Co., Ltd., standard CICA grade 1)

* 5: Thioglycolic acid (manufactured by Kanto Kagaku Co., Ltd., standard CICA grade 1)

* 6: Malonic acid (manufactured by Kanto Kagaku Co., Ltd., standard CICA grade 1)

* 7: BYK-354 (manufactured by Big Chemie Japan)

As shown in Table 1, in Examples 1 to 3 using thiodiglycolic acid or derivatives thereof, resistivity values were obtained on the order of 10 &lt; ^-5 &gt; ([Omega] -cm), and it was confirmed that the resistivity was low. On the other hand, Comparative Example 1 in which at least one of the derivatives of thiodiglycolic acid and thiodiglycolic acid was not used, a glycolic acid, a thioglycolic acid, a thiodiglycolic acid or a thiodiglycolic acid was used in place of at least one of the derivatives of thiodiglycolic acid and thiodiglycolic acid , And Comparative Examples 2, 3 and 4 using malonic acid, respectively, it was confirmed that the resistivity value of 10 ^-5 (Ω · cm) order was not obtained, and the resistivity value was higher than that of Example.

[Photosensitive conductive paste]

&Lt; Preparation of Photosensitive Conductive Paste >

The components were mixed with each other in the composition ratios shown in Table 2 below and stirred with a stirrer. The mixture was kneaded by three-roll milling to make paste, and each of the photosensitive conductive pastes of Examples 4 and 5, Reference Example 1 and Comparative Example 5 . The lightness L ^* value of the conductive powder used for the photosensitive conductive paste is a value measured according to JIS standard Z8722.

* 1: silver powder; Lightness L ^* = 70, average particle diameter = 2 占 퐉

* 2: silver powder; Lightness L ^* = 58, average particle diameter = 1.5 占 퐉

* 3: Oxime ester-based photopolymerization initiator; NCI-831 (manufactured by Adeka)

* 4: Thioxanthene photopolymerization initiator; KAYACURE DETX-S (manufactured by Nippon Kayaku Co., Ltd.)

* 5: Acetaminophenone-based polymerization initiator; IRGACURE 379 (manufactured by BASF Japan)

* 6: 2,2'-thiodiglycolic acid (manufactured by Kanto Chemical Co., Ltd .; standard CICA grade 1)

* 7: M-350 (manufactured by Toagosei Co., Ltd.)

* 8 Carbitol acetate

* 9: BYK-354 (manufactured by Big Chemie Japan)

* 10: Calculated based on non-volatile components

(Evaluation of Resolution)

Each photosensitive conductive paste was coated on a glass substrate using a 200 mesh polyester screen to have a wet film thickness of 14 mu m and dried in an IR drying furnace at 100 DEG C for 20 minutes to form a dry film. The film thickness of the dried film after drying was 10 mu m.

Next, a straight line pattern negative mask having a line resolution of 10/20 / ~90 / 100 mu m was used as a light source for the obtained dry film using a super high pressure mercury vapor lamp and remaining resolution through a negative mask. Negative / positive inverse patterns of the negative resolution of the remaining resolution were used for the output resolution. Each dry film was subjected to pattern exposure at 200 mJ / cm 2, developed with a 0.4% sodium carbonate aqueous solution having a liquid temperature of 30 ° C for 10 seconds and 20 seconds, and washed with water.

Remaining resolution; Negative mask design value of minimum residual pattern.

Output resolution; Negative mask design value for minimum patterned space.

The measurement results are shown in Table 3 below.

(Evaluation of Resistivity Value)

A rectangular pattern with a negative design of 0.4 x 10 (cm) was formed, and a resistivity value was calculated from the resistance value after film curing and the film thickness. The measurement results are shown in Table 3.

As shown in Table 3, it can be seen that Examples 4 and 5 using the photosensitive conductive paste of this embodiment using thiodiglycolic acid have lower resistance than Comparative Example 5 in which thiodiglycolic acid is not used. Further, in Examples 4 and 5 using an oxime ester system as a photopolymerization initiator, it was found that, in addition to low resistance, the remaining resolution and the output resolution were better than those of Reference Example 1 in which the oxime ester system was not used in the photopolymerization initiator . From the results of Examples 4 and 5, it can be seen that the photosensitive conductive paste of this embodiment has good patterning regardless of the brightness L ^* value of the conductive powder.

Claims (9)

Characterized in that it contains an electrically conductive powder, an organic binder, at least one of thiodiglycolic acid and a derivative of thiodiglycolic acid, and an oxime ester photopolymerization initiator and does not contain a glass powder. Conductive paste. The conductive paste according to claim 1, wherein the conductive powder comprises silver powder. The conductive paste according to claim 1, wherein at least one of the thiodiglycolic acid and thiodiglycolic acid derivatives is in a solid content of 0.01 to 10 parts by mass per 100 parts by mass of the organic binder. The conductive paste according to claim 1, further comprising a photopolymerizable monomer. A conductive circuit formed by using the conductive paste according to claim 1. delete delete delete delete