TWI704417B - Photosensitive conductive paste and method for manufacturing substrate with conductive pattern - Google Patents

Abstract

The present invention is a photosensitive conductive paste containing: conductive particles (A), a compound having an unsaturated double bond (B), a photopolymerization initiator (C), and a compound having a hydroxypyridine skeleton in one molecule (D).

The present invention provides a photosensitive conductive paste capable of producing a fine conductive pattern with good straightness and high conductivity.

Description

Photosensitive conductive paste and method for manufacturing substrate with conductive pattern

The present invention relates to a photosensitive conductive paste capable of forming a fine conductive pattern and a method for producing a substrate with a conductive pattern formed using the photosensitive conductive paste.

Background technique

In recent years, it has become possible to produce fine conductive patterns by the photolithographic method. Regarding the conductive paste to be used, a photosensitive conductive paste obtained by dispersing a conductive filler in a photosensitive organic component has been developed and proposed (see Patent Documents 1 and 2). By using such a photosensitive conductive paste, it becomes possible to form conductive patterns with a pitch of about tens of μm. However, if the space between the conductive patterns becomes narrow due to the narrowing of the pitch, there is a possibility of a short circuit between the patterns. High topics like this. Therefore, it has been proposed to use a method of adding an ultraviolet absorber to suppress the line thickening of the conductive pattern after exposure to form a conductive pattern with good straightness (see Patent Document 3).

Advanced technical literature Patent literature

Patent Document 1 International Publication No. 2013/108696 Pamphlet

Patent Document 2 International Publication No. 2013/146107 Pamphlet

Patent Document 3 JP 2013-196998 A

Summary of the invention

However, when a fine conductive pattern with good straightness is formed by adding a UV absorber, even if the specific resistance value is the same as before the addition, the line width becomes thinner and the circuit resistance increases.

The present invention provides a photosensitive conductive paste which forms a fine conductive pattern with good linearity and exhibits high conductivity.

As a result of intensive investigations by the present inventors, they found that moderately reducing the reactivity of organic components contributes to the formation of fine conductive patterns with good straightness and high electrical conductivity. That is, by appropriately reducing the reactivity of the organic component, it becomes possible to suppress the riot of radical polymerization during exposure, and to form a fine conductive pattern with good straightness. In addition, since the reaction of the organic component does not progress excessively at the time point after the exposure, curing shrinkage during heating occurs, and the contact probability of conductive fillers increases, and high conductivity is exhibited. It has been found that by containing a compound having a hydroxypyridine skeleton as an organic component, the reactivity of the organic component can be moderately suppressed, the formation of a fine conductive pattern with good linearity can be achieved, and both high conductivity can be exhibited, and the present invention has been completed.

The present invention is a photosensitive conductive paste containing: conductive particles (A), a compound having an unsaturated double bond (B), a photopolymerization initiator (C), and a compound having a hydroxypyridine skeleton in one molecule ( D).

According to a preferable aspect of the photosensitive conductive paste of the present invention, the aforementioned compound (D) having a hydroxypyridine skeleton in one molecule is a compound having a hydroxymethyl group.

According to a preferred aspect of the photosensitive conductive paste of the present invention, the content of the compound (D) having a hydroxypyridine skeleton in one molecule relative to 100 parts by mass of the compound (B) having an unsaturated double bond is 0.3~ 10 parts by mass.

According to a preferable aspect of the photosensitive conductive paste of the present invention, it contains a thermosetting resin (E).

According to a preferred aspect of the photosensitive conductive paste of the present invention, the thermosetting resin (E) is an epoxy resin having an epoxy equivalent of 150 to 500 g/equivalent.

The present invention can manufacture a substrate with a conductive pattern by applying the aforementioned photosensitive conductive paste on a substrate and then curing it at a temperature of 100 to 300°C.

According to the present invention, a photosensitive conductive paste with a low specific resistance value can be obtained, which can form a fine conductive pattern with good straightness.

The photosensitive conductive paste of the present invention can be suitably used for manufacturing conductive patterns such as peripheral wiring for touch panels.

1‧‧‧Maximum line width

2‧‧‧Minimum line width

A‧‧‧Light transmission pattern

B‧‧‧Conductive pattern made by using L/S=20/20 mask

Fig. 1 is a schematic diagram showing the measurement locations in the straightness evaluation of the examples.

FIG. 2 is a schematic diagram showing the light transmission pattern of the photomask used in the specific resistance evaluation of the embodiment.

The form used to implement the invention

The photosensitive conductive paste of the present invention contains conductive particles (A), a compound having an unsaturated double bond (B), a photopolymerization initiator (C), and a compound (D) having a hydroxypyridine skeleton in one molecule.

The conductive pattern obtained by the photosensitive conductive paste of the present invention becomes a composite of an organic component and an inorganic component, and the conductive particles (A) are in contact with each other due to the curing shrinkage during heat curing, thereby exhibiting conductivity Sex.

The conductive particles (A) contained in the photosensitive conductive paste of the present invention preferably include: silver, gold, copper, platinum, lead, tin, nickel, aluminum, tungsten, molybdenum, chromium, titanium, and The conductive filler of at least one type of indium can be used alone, as an alloy, or as a mixed powder. In the same way, conductive particles obtained by coating the surfaces of insulating particles or conductive particles such as resins and inorganic oxides with the aforementioned components can also be used. Among them, from the viewpoint of conductivity, silver, gold, or copper is preferable, and from the viewpoint of cost and stability, it is more preferable to use silver.

Regarding the shape of the conductive particle (A), a value obtained by dividing the long axis length by the short axis length, that is, the aspect ratio is preferably 1.0 to 3.0, and more preferably 1.0 to 2.0. If the aspect ratio of the conductive particles (A) is 1.0 or more, the contact probability of the conductive particles (A) can be more improved. On the other hand, when the aspect ratio of the conductive particles (A) is 2.0 or less, when the wiring is formed by the photolithography method, the exposure light is not easily shielded, and the development margin can be wide.

The aspect ratio of the conductive particles (A) is to observe the conductive particles (A) with a scanning electron microscope (SEM) or a transmission electron microscope (TEM) at a magnification of 15000 times, and randomly select 100 primary particles of the conductive particles , Measure each major axis length and minor axis length, and obtain the aspect ratio from the average of the two.

The particle size of the conductive particles (A) is preferably 0.05 to 5.0 μm, more preferably 0.1 to 2.0 μm. When the particle size of the conductive particles (A) is 0.05 μm or more, the interaction between the particles is weak, and the dispersion state of the conductive particles (A) in the paste is easily maintained. If the particle size of the conductive particles (A) is 5.0 μm or less, the surface smoothness, pattern precision, and dimensional precision of the produced conductive pattern can be improved.

The particle size of the conductive particles (A) contained in the photosensitive conductive paste was observed with an electron microscope, randomly selected 20 primary particles of conductive particles, measured the maximum width of each, and obtained the average value And figure it out.

The content of the conductive particles (A) is preferably 60 to 95% by mass, and more preferably 75 to 90% by mass relative to the total solid content in the conductive paste. If the content of the conductive particles (A) relative to the total solid content is 60% by mass or more, the probability of contact between the conductive particles (A) during curing increases, and the specific resistance and the probability of wire breakage of the manufactured conductive pattern are reduced . If the content of the conductive particles (A) with respect to the total solid content is 95% by mass or less, the light transmittance of the coating film is improved in the exposure step, and fine patterning becomes easy. The term "all solids" as used herein refers to all components of the photosensitive conductive paste except for the solvent.

The compound (B) having an unsaturated double bond contained in the photosensitive conductive paste of the present invention includes, for example, styrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, Styrenes such as α-methylstyrene, chloromethylstyrene or hydroxymethylstyrene, acrylic monomers, acrylic copolymers, epoxy carboxylate compounds, and 1-vinyl-2-pyrrolidine ketone.

For acrylic monomers, for example, acrylic acid, methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, isobutyl acrylate, isopropyl acrylate, glycidyl acrylate, Butoxy triethylene glycol acrylate, dicyclopentyl acrylate, dicyclopentenyl acrylate, 2-hydroxyethyl acrylate, isobornyl acrylate, 2-hydroxypropyl acrylate, isodecyl acrylate, isooctyl acrylate Ester, lauryl acrylate, 2-methoxyethyl acrylate, methoxyglycol acrylate, methoxydiethylene glycol acrylate, octafluoropentyl acrylate, phenoxyethyl acrylate, stearyl acrylate Ester, trifluoroethyl acrylate, aminoethyl acrylate, phenyl acrylate, phenoxyethyl acrylate, 1-naphthyl acrylate, 2-naphthyl acrylate, thiophenol acrylate, or benzyl mercaptan acrylic acid Ester (benzyl mercaptan acrylate), allylated cyclohexyl diacrylate, methoxylated cyclohexyl diacrylate, 1,4-butanediol diacrylate, 1,3-butanediol diacrylate, ethyl Glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate, polypropylene glycol diacrylate or triethylene glycol diacrylate Glycerol diacrylate, trimethylolpropane triacrylate, di-trimethylolpropane tetraacrylate, dineopentaerythritol monohydroxy pentaacrylate Ester or dineopentaerythritol hexaacrylate, acrylamide, N-methoxymethacrylamide, N-ethoxymethacrylamide, N-n-butoxymethacrylamide or N -Isobutoxy methacrylamide, acrylic acid adduct of ethylene glycol diglycidyl ether with hydroxyl group formed by opening the epoxy group with unsaturated acid, acrylic acid of diethylene glycol diglycidyl ether Adducts, acrylic acid adducts of neopentyl glycol diglycidyl ether, acrylic acid adducts of glycerol diglycidyl ether, acrylic acid adducts of bisphenol A diglycidyl ether, acrylic acid adducts of bisphenol F Or epoxy acrylate monomers such as acrylic adducts of cresol novolac or γ-acryloxypropyl trimethoxysilane, or compounds obtained by substituting these acryloxy groups with methacryloxy groups .

The acrylic copolymer refers to a copolymer containing an acrylic monomer as a monomer that can be used, that is, a copolymerization component. The alkali-soluble acrylic copolymer having a carboxyl group can be obtained by using an unsaturated acid such as an unsaturated carboxylic acid as a monomer. Examples of unsaturated acids include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, or vinyl acetate, and anhydrides of these. The acid value of the obtained acrylic copolymer can be adjusted by the amount of unsaturated acid used. Furthermore, by reacting the carboxyl group of the acrylic copolymer with a compound having an unsaturated double bond such as glycidyl (meth)acrylate, an alkali-soluble acrylic acid having a reactive unsaturated double bond in the side chain can be obtained Department of copolymers.

The epoxy carboxylate compound is a compound that can be synthesized using an epoxy compound and a carboxyl compound having an unsaturated double bond as starting materials. Can become the epoxy compound of the starting material and Examples include: glycidyl ethers, alicyclic epoxy resins, glycidyl esters, glycidylamines or epoxy resins, more specifically: methyl glycidyl ether, ethyl glycidyl ether , Butyl glycidyl ether, ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, bisphenol A two Glycidyl ether, hydrogenated bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, bisphenol diglycidyl ether, diphenol diglycidyl ether, tetramethyl diphenol glycidyl ether Glyceryl ether, trimethylolpropane triglycidyl ether, 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, and tributyl glycidylamine. In addition, examples of the carboxy compound having an unsaturated double bond include (meth)acrylic acid, crotonic acid, cinnamic acid, and α-cyanocinnamic acid.

The epoxy carboxylate compound and the polybasic acid anhydride are reacted to adjust the acid value of the epoxy carboxylate compound. For polybasic acid anhydrides, for example, succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, itaconic anhydride, 3-methyltetrahydrophthalic anhydride, 4-methyl Base-hexahydrophthalic anhydride, trimellitic anhydride and maleic anhydride. By reacting the carboxyl group of the epoxy carboxylate compound that reacts with the above-mentioned polybasic acid anhydride with a compound having an unsaturated double bond such as glycidyl (meth)acrylate, the reactivity of the epoxy carboxylate compound can be adjusted The amount of unsaturated double bonds.

By reacting the hydroxyl group of the epoxy carboxylate compound with the diisocyanate compound, urethane can be carried out. As for the diisocyanate compound, for example, hexamethylene diisocyanate, Tetramethylxylene diisocyanate, naphthalene-1,5-diisocyanate, tolidene diisocyanate, trimethylhexamethylene diisocyanate, isophorone diisocyanate, allyl cyano diisocyanate, and Norbornane diisocyanate.

In order to optimize alkali solubility, the acid value of the compound (B) having an unsaturated double bond is preferably 30 to 250 mgKOH/g. When the acid value of the compound (B) having an unsaturated double bond is 30 mgKOH/g or more, the solubility of the soluble part can be suppressed. When the acid value of the compound (B) having an unsaturated double bond is 250 mgKOH/g or less, the allowable development range can be maintained. The acid value of the compound (B) having an unsaturated double bond can be measured in accordance with JIS K 0070 (1992).

啉基丙烷-1-酮、2-苄基-2-二甲基胺基-1-(4-

啉基苯基)-丁烷-1-酮、2-二甲基胺基-2-(4-甲基苄基)-1-(4-

啉-4-基-苯基)丁烷-1-酮等α-胺基烷基苯酮系化合物；2,4,6-三甲基苯甲醯基-二苯基-氧化膦、雙(2,4,6-三甲基苯甲醯基)-苯基氧化膦等氧化膦系化合物；萘磺醯氯、喹啉磺醯氯等芳香族磺醯氯系化合物；蒽醌、2-三級丁基蒽醌、2-戊基蒽醌、β-氯蒽醌、蒽酮、苯并蒽酮、二苯并環庚酮(dibenzosuberone)、亞甲基蒽酮、2,6-雙(對疊氮基亞苄基)環己酮、6-雙(對疊氮基亞苄基)-4-甲基環己酮、2,6-雙(對疊氮基亞苄基)環己酮、6-雙(對疊氮基亞苄基)-4-甲基環己酮、N-苯基硫吖啶酮、4,4’-偶氮雙異丁腈、二苯基二硫化物、苯并噻唑二硫化物、三苯基膦、樟腦醌、四溴化碳、三溴苯基碸、過氧化苯甲醯等，特佳可使用光感度高的肟系化合物。 The photopolymerization initiator (C) contained in the photosensitive conductive paste of the present invention includes, for example, benzophenone, methyl phthalate, 4,4'-bis(dimethyl Amino) benzophenone, 4,4'-bis(diethylamino) benzophenone, 4,4'-dichlorobenzophenone, 4-benzyl-4'-methanone Benzophenone derivatives such as benzophenone and quinone; p-tertiary butyldichloroacetophenone, 4-azidobenzylidene acetophenone, 2,2'-diethoxybenzene Acetophenone derivatives such as ethyl ketone; thioxanthone derivatives such as thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone and diethylthioxanthone; Benzyl derivatives such as benzyl, benzyl dimethyl ketal, and benzyl-β-methoxyethyl acetal; benzoin derivatives such as benzoin, benzoin methyl ether, and benzoin butyl ether ; 1,2-octanedione-1-[4-(phenylsulfide)-2-(O-benzyl oxime)], ethyl ketone-1-[9-ethyl-6-(2- Methylbenzyl)-9H-carbazol-3-yl)-1-(O-acetoxime), 1-phenyl-1,2-butanedione-2-(O-methoxycarbonyl) )Oxime, 1-phenyl-propanedione-2-(O-ethoxycarbonyl)oxime, 1-phenyl-propanedione-2-(O-benzyl)oxime, 1,3-bis Phenyl-glycerol-2-(O-ethoxycarbonyl)oxime, 1-phenyl-3-ethoxy-glycerol-2-(O-benzyl)oxime and other oxime compounds; 2-hydroxy-2-methyl-1-phenyl-propane-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane -1-ketone and other α-hydroxy ketone compounds; 2-methyl-(4-methylphenylthio)-2-

Alkylpropane-1-one, 2-benzyl-2-dimethylamino-1-(4-

Alkylphenyl)-butane-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-

Alpha-aminoalkylphenone compounds such as lin-4-yl-phenyl)butan-1-one; 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide, bis( 2,4,6-trimethylbenzyl)-phenylphosphine oxide and other phosphine oxide compounds; naphthalenesulfonyl chloride, quinolinesulfonyl chloride and other aromatic sulfonyl chloride compounds; anthraquinone, 2-tri Grade butyl anthraquinone, 2-pentyl anthraquinone, β-chloroanthraquinone, anthrone, benzoanthrone, dibenzosuberone, methylene anthrone, 2,6-bis(p) Azidobenzylidene) cyclohexanone, 6-bis(p-azidobenzylidene)-4-methylcyclohexanone, 2,6-bis(p-azidobenzylidene)cyclohexanone, 6-bis(p-azidobenzylidene)-4-methylcyclohexanone, N-phenylthioacridone, 4,4'-azobisisobutyronitrile, diphenyl disulfide, benzene Thiazole disulfide, triphenylphosphine, camphorquinone, carbon tetrabromide, tribromophenyl sulfide, benzyl peroxide, etc., especially oxime compounds with high photosensitivity can be used.

The content of the photopolymerization initiator (C) is preferably 0.05 to 30 parts by mass, and more preferably 1 to 10 parts by mass relative to 100 parts by mass of the compound (B) having an unsaturated double bond. When the content of the photopolymerization initiator (C) is 0.05 parts by mass or more with respect to 100 parts by mass of the compound (B) having an unsaturated double bond, the curing density of the exposed area increases, and the residual film rate after development can be increased. With respect to 100 parts by mass of the compound (B) having an unsaturated double bond, When the content of the photopolymerization initiator (C) is 30 parts by mass or less, excess light absorption due to the photopolymerization initiator (C) on the upper portion of the coating film obtained by applying the conductive paste is suppressed. As a result, the reduction in adhesion to the substrate due to the manufactured conductive pattern becoming an inverted tapered shape is suppressed.

The photosensitive conductive paste of the present invention can contain a sensitizer together with the photopolymerization initiator (C).

As a sensitizer, for example, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,3-bis(4-diethylaminobenzylidene)cyclopentanone, 2,6-bis(4-dimethylaminobenzylidene)cyclohexanone, 2,6-bis(4-dimethylaminobenzylidene)-4-methylcyclohexanone, rice Michler's ketone, 4,4-bis(diethylamino)benzophenone, 4,4-bis(dimethylamino)chalcone, 4,4-bis(diethyl) Amino) chalcone, p-dimethyl amino cinnamylidene indanone (p-dimethyl amino cinnamylidene indanone), p-dimethylamino benzylidene indanone, 2-(p-dimethylamino cinnamylidene indanone) Methylaminophenyl vinylene) isonaphththiazole, 1,3-bis(4-dimethylaminophenyl vinylene) isonaphththiazole, 1,3-bis(4-dimethylamino) Benzylidene)acetone, 1,3-carbonylbis(4-diethylaminobenzylidene)acetone, 3,3-carbonylbis(7-diethylaminocoumarin), N-benzene -N-ethylethanolamine, N-phenylethanolamine, N-tolyldiethanolamine, isoamyl dimethylaminobenzoate, isoamyl diethylaminobenzoate, 3-phenyl-5- Benzylthiotetrazole, and 1-phenyl-5-ethoxycarbonylthiotetrazole.

The content of the sensitizer is preferably 0.05 to 10 parts by mass relative to 100 parts by mass of the compound (B) having an unsaturated double bond. Relative to 100 parts by mass of the compound (B) having an unsaturated double bond, the content of the sensitizer is If it is 0.05 parts by mass or more, the light sensitivity is improved. When the content of the sensitizer is 10 parts by mass or less with respect to 100 parts by mass of the compound (B) having an unsaturated double bond, excess light absorption is suppressed on the upper part of the coating film obtained by applying the conductive paste. As a result, the manufactured conductive pattern becomes an inverted tapered shape, and the decrease in adhesion to the substrate is suppressed.

The compound (D) having a hydroxypyridine skeleton in one molecule contained in the photosensitive conductive paste of the present invention includes, for example, 2-hydroxypyridine, 3-hydroxypyridine, 4-hydroxypyridine, 2,4 -Dihydroxypyridine, 2,4-dihydroxyquinoline, 2,6-dihydroxyquinoline, 2,8-dihydroxyquinoline, 5-hydroxy-2-methylpyridine, 2-hydroxy-4-methyl Pyridine, 2-hydroxy-5-methylpyridine, 2-hydroxy-6-methylpyridine, 2,4-dihydroxy-6-methylpyridine, 2-ethyl-3-hydroxy-6-methylpyridine, 4-bromo-2-hydroxypyridine, 4-chloro-2-hydroxypyridine, 2-hydroxy-5-iodopyridine, 3-hydroxyisoquinoline, 2-quinolinol, 3-quinolinol, 2-methyl -4-quinolinol, pyridoxal-5-phosphate, citrazine, 6-hydroxynicotinic acid, and these salts.

Among them, pyridoxine, 4-deoxypyridoxine, pyridoxal, pyridoxamine, 4-pyridoxic acid), isopyridoxal, 2-hydroxymethyl-3-pyridinol (2-hydroxymethyl-3-pyridinol), 2-hydroxymethyl-6-methyl-3-pyridinol, 2,6-bis( (Hydroxymethyl)-3-pyridinol, ginkgotoxin, pyridoxine dicaprylate, pyridoxal oxime, 6-(hydroxymethyl)-3,4-pyridinediol, 2-bromo-6 -(Hydroxymethyl)-3-pyridinol, 2,5-dichloro-6-(hydroxymethyl)-3-pyridinol, 2-chloro-6-(hydroxymethyl)-4-iodo-3- Pyridinol, 3-(hydroxymethyl)-6-methyl-4-quinolinol, pyridoxine-3,4-di Palmitate and these salts are not too strong because of the reaction inhibition effect of organic components, and the development limit of the conductive pattern is not easily deteriorated.

The content of the compound (D) having a hydroxypyridine skeleton in one molecule is preferably 0.3-10 parts by weight, and more preferably 0.5-5 parts by weight relative to 100 parts by weight of the compound (B) having an unsaturated double bond. If the content of the compound (D) having a hydroxypyridine skeleton in one molecule is 0.3 parts by mass or more with respect to 100 parts by mass of the compound (B) having an unsaturated double bond, it will prevent the riot of radical reactions due to exposure to light. The straightness of the conductive pattern is improved, and since the curing of the resin component of the conductive pattern does not proceed excessively at the time point before curing, the curing shrinkage during curing is not hindered, and the probability of contact between the conductive particles (A) is increased, The specific resistance value will decrease. If the content of the compound (D) having a hydroxypyridine skeleton in one molecule is 10 parts by mass or less relative to 100 parts by mass of the compound (B) having an unsaturated double bond, the photoradical reaction will not be excessively suppressed. Therefore, fine patterning becomes possible.

The photosensitive conductive paste of the present invention can contain a thermosetting resin (E). Examples of the thermosetting resin (E) include epoxy resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, silicone resin, and polyurethane. Regarding the thermosetting resin (E), among them, epoxy resin is preferred, and among epoxy resins, epoxy resin having an epoxy equivalent of 150 to 500 g/equivalent is preferred. By setting the epoxy equivalent of the epoxy resin to 150 g/equivalent or more, a photosensitive conductive paste with storage stability of the coating film can be obtained. By setting the epoxy equivalent of the epoxy resin to 500 g/equivalent or less, a conductive pattern with high adhesion to various substrates such as a resin film and a glass substrate can be obtained.

The epoxy equivalent refers to the mass of a resin containing 1 equivalent of epoxy groups, and is obtained by dividing the molecular weight obtained from the structural formula by the number of epoxy groups contained in the structure.

The content of the epoxy resin is preferably in the range of 1 to 100 parts by mass, and more preferably 30 to 80 parts by mass relative to 100 parts by mass of the compound (B) having an unsaturated double bond. With respect to 100 parts by weight of the compound (B) having an unsaturated double bond, the content of the epoxy resin is set to 1 part by mass or more, so that the effect of improving the adhesion is easily fully exhibited. If the content of the compound (B) having an unsaturated double bond is 100 parts by mass or less, a photosensitive conductive paste having particularly high storage stability of the coating film can be obtained.

Regarding the epoxy resin, those having an epoxy equivalent in the range of 150 to 500 g/equivalent are preferable, and those in the range of 200 to 500 g/equivalent are more preferable. Specific examples include: glycol modified epoxy resin, bisphenol A epoxy resin, brominated epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, alicyclic epoxy resin Epoxy resin, glycidylamine type epoxy resin, glycidyl ether type epoxy resin, and heterocyclic epoxy resin, etc.

The photosensitive conductive paste of the present invention can contain a solvent. Examples of solvents include: N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylimidazolidinone, dimethylsulfoxide , Γ-butyrolactone, ethyl lactate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, ethylene glycol mono-n-propyl ether, diacetone alcohol, tetrahydrofurfuryl alcohol, Propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether acetate (hereinafter referred to as "DMEA"), diethylene glycol monobutyl Ether, diethylene glycol, and 2,2,4,-trimethyl-1,3-pentanediol monoisobutyrate are preferably solvents with a boiling point of 150°C or higher. If the boiling point is 150°C or higher, the volatilization of the solvent is suppressed and the thickening of the conductive paste can be suppressed.

As long as the desired characteristics are not impaired, the photosensitive conductive paste of the present invention can be made to contain a non-photosensitive polymer without unsaturated double bonds in the molecule, a plasticizer, a leveling agent, and an interface active Additives such as additives, silane coupling agents, defoamers, and pigments.

Examples of non-photosensitive polymers include polyethylene terephthalate, polyimide precursors, and ring-closed polyimides.

As the plasticizer, for example, dibutyl phthalate, dioctyl phthalate, polyethylene glycol and glycerin can be mentioned.

As the leveling agent, for example, a special vinyl polymer and a special acrylic polymer can be mentioned.

As for the silane coupling agent, for example, methyltrimethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexamethyldisilazane, 3-methacryloxypropyl Trimethoxysilane, 3-glycidoxypropyltrimethoxysilane (3-glycidoxypropyltrimethoxysilane), and vinyl trimethoxysilane.

The photosensitive conductive paste of the present invention is manufactured using a disperser or kneader such as a three-roll mill, a ball mill, or a planetary ball mill.

The method for manufacturing a substrate with a conductive pattern of the present invention is to apply the photosensitive conductive paste of the present invention on the substrate, dry, expose and develop, and then cure it at a temperature of 100 to 300°C.

A coating film is obtained by applying the photosensitive conductive paste of the present invention on a substrate. Examples of substrates coated with photosensitive conductive paste include polyethylene terephthalate film (hereinafter referred to as PET film), polyimide film, polyester film, aramid film, epoxy Resin substrates, polyetherimide resin substrates, polyetherketone resin substrates, polycarbonate resin substrates, glass substrates, silicon wafers, alumina substrates, aluminum nitride substrates, silicon carbide substrates, decorative layer forming substrates, and The insulating layer forms the substrate.

The method of applying the photosensitive conductive paste of the present invention to a substrate includes, for example, spin coating using a spinner, spray coating, roll coating, screen printing, or use of a blade coater (blade coater), die coating Machine, calender coater, meniscus coater or bar coater.

The film thickness of the obtained coating film can be appropriately determined according to the coating method or the total solid content concentration or viscosity of the photosensitive conductive paste, but the film thickness after drying is preferably 0.1-50 μm. The film thickness can be measured using a probe profiler such as Surfcom (registered trademark) 1400 (manufactured by Tokyo Seimitsu Co., Ltd.). More specifically, the film thickness of three randomly selected positions is measured with a probe profiler (measurement length: 1mm, scanning speed: 0.3mm/sec), and the average value is calculated. .

The coating film is dried to volatilize the solvent. The method of drying the coating film to volatilize and remove the solvent includes, for example, heat drying and vacuum drying by an oven, a hot plate, or infrared rays. The heating temperature is preferably 50 to 180°C, and the heating time is preferably 1 minute to several hours.

The dried coating film is exposed through an arbitrary pattern forming mask and is exposed by photolithography. As for the light source for exposure, the i-line (365nm), h-line (405nm) or g-line (436nm) of a mercury lamp is preferably used.

The coated film after exposure is developed using development, and the unexposed part is dissolved and removed to obtain a desired pattern. As for the developer during alkaline development, for example, tetramethylammonium hydroxide, diethanolamine, diethylaminoethanol, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, Diethylamine, methylamine, dimethylamine, dimethylaminoethyl acetate, dimethylaminoethanol, dimethylaminoethyl methacrylate, cyclohexylamine, ethylenediamine or hexamethylenediamine Aqueous solution.

To these aqueous solutions can be added: N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfide or γ-butyrolactone And other polar solvents; alcohols such as methanol, ethanol or isopropanol; esters such as ethyl lactate or propylene glycol monomethyl ether acetate; cyclopentanone, cyclohexanone, isobutyl ketone or methyl isobutyl ketone, etc. Ketones; and surfactants.

As for the developer for organic development, for example, N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N,N-dimethylacetamide, Polar solvents such as N,N-dimethylformamide, dimethylsulfide, or hexamethylphosphortriamide, or such polar solvents and methanol, ethanol, isopropanol, xylene, water, methyl A mixed solution of carbitol and ethyl carbitol.

The development method includes, for example, a method of allowing the substrate to stand or rotate and spraying the developer on the surface of the coating film, a method of immersing the substrate in the developer, and immersing the substrate in the developer. The method of applying ultrasound.

The conductive pattern obtained by development can be rinsed with a rinse liquid. Here, the rinsing liquid includes, for example, water or an aqueous solution obtained by adding alcohols such as ethanol or isopropanol to water, or esters such as ethyl lactate or propylene glycol monomethyl ether acetate.

The obtained conductive pattern is cured at a temperature of 100~300℃. The curing temperature is preferably 120 to 180°C. If the curing temperature is lower than 100°C, the volume shrinkage of the resin component does not increase, and the specific resistance does not decrease sufficiently. If the curing temperature exceeds 300°C, it becomes difficult to manufacture conductive patterns on materials such as substrates with low heat resistance.

The method of hardening the obtained conductive pattern includes, for example, heating and drying by an oven, inert oven, or hot plate, and electromagnetic waves such as ultraviolet lamps, infrared heaters, halogen heaters, or xenon flash lamps. Either heating and drying by microwave or vacuum drying. The hardness of the produced conductive pattern is increased by heating, it is possible to suppress chipping and peeling due to contact with other members, and to further improve the adhesion to the substrate.

The conductive pattern obtained by using the photosensitive conductive paste of the present invention can be suitably used in touch panels, laminated ceramic capacitors, laminated inductors, solar cells, etc. Among them, it can be more suitably used for narrow Peripheral wiring for touch panels that require miniaturization due to frame size.

Example

Next, the photosensitive conductive paste of the present invention will be described with examples.

The evaluation method used in each example is as follows.

<Method for evaluating patterning properties>

The photosensitive conductive paste was coated on the PET film so that the film thickness after drying became 4 μm, and dried in a drying oven at 100° C. for 5 minutes. A group of straight lines arranged with a certain line and space (hereinafter referred to as L/S), that is, the light transmission pattern is set as one unit, and 10 types of units with different values of L/S are passed through Expose and develop the dried coating film to obtain 10 types of patterns with different L/S values. After that, the obtained 10 patterns were cured in a drying oven at a temperature of 140° C. for 30 minutes to obtain 10 types of conductive patterns with different L/S values. The value of L/S of each unit of the mask, the line width L(μm)/space S(μm) is 250/250, 100/100, 50/50, 40/40, 30/30, 25/25, 20/20, 15/15, 10/10 and 7/7. The obtained conductive pattern was observed with an optical microscope. It was confirmed that there was no residue between the patterns and no pattern peeling, and the L/S value was the smallest conductive pattern. Let the value of L/S be the value of L/S that can be developed.

Exposure is to use an exposure device (PEM-6M; manufactured by UNION Optical Co., Ltd.) to perform full-line exposure with an exposure amount of 150mJ/cm ² (converted to a wavelength of 365nm). Development is to immerse the substrate in a 0.2 mass% Na ₂ CO ₃ solution for 30 seconds After that, rinsing treatment with ultrapure water is performed.

<Method of evaluating straightness>

For the light-transmitting pattern B whose L/S value of the conductive pattern used in the evaluation of the patternability is 20/20, the line width shown in FIG. 1 is randomly set to the thickest maximum line width 1, The smallest line width 2 with the thinnest line width was measured at 10 locations, and the average value of each was obtained. Use the obtained "average maximum line width" and "average minimum line width" to calculate based on the following formula (1) The length of the protrusion protruding from the pattern. Regarding the straightness, set the protrusion length less than 2μm as "A very good", set the length of 2μm or more and less than 4μm as "B good", and set the length of 4μm or more as "C difference", and set "A very good". Set as good" and "B good" as qualified.

The length of the protrusion = (average maximum line width-average minimum line width)/2...Equation (1).

<Evaluation method of specific resistance>

The photosensitive conductive paste was coated on the PET film so that the film thickness after drying became 4 μm, and the coated film was dried in a drying oven at a temperature of 100° C. for 5 minutes. Through the photomask with the light-transmitting pattern A shown in FIG. 2, the dried coating film is exposed and developed to obtain a conductive pattern. After that, the obtained conductive pattern was cured in a drying oven at a temperature of 140° C. for 30 minutes to obtain a conductive pattern for measuring specific resistance. The line width of the obtained conductive pattern was 20 μm, and the line length was 80 mm.

The conditions of exposure and development are the same as the above-mentioned evaluation method of patternability. The resistance value was measured by connecting the respective ends of the obtained conductive pattern for measuring the specific resistance with a resistance meter, and the specific resistance was calculated based on the following formula (2).

Specific resistance=resistance value×film thickness×line width/line length...Equation (2).

The materials used in each example are as follows.

[Conductive particles (A)]

Ag particles with a volume average particle diameter of 1.0 μm.

[Compound with unsaturated double bond (B)]

(Synthesis Example 1: Compound (B-1))

Copolymerization ratio (based on mass): ethyl acrylate (hereinafter referred to as EA)/2-ethylhexyl methacrylate (hereinafter referred to as 2-EHMA)/styrene (hereinafter referred to as St)/methyl Glycidyl acrylate (hereinafter referred to as GMA)/acrylic acid (hereinafter referred to as AA)=20/40/20/5/15.

In a reaction vessel in a nitrogen atmosphere, 150 g of DMEA was fed, and an oil bath was used to raise the temperature to 80°C. A mixture containing 20 g of EA, 40 g of 2-EHMA, 20 g of St, 15 g of AA, 0.8 g of 2,2'-azobisisobutyronitrile, and 10 g of DMEA was dropped in 1 hour. After the dropping, the polymerization reaction was further carried out for 6 hours. After that, 1 g of hydroquinone monomethyl ether was added to stop the polymerization reaction. Then, a mixture containing 5 g of GMA, 1 g of triethylbenzylammonium chloride (triethylbenzylammonium chloride), and 10 g of DMEA was dropped over 0.5 hours. After completion of the dropping, the addition reaction was further carried out for 2 hours. The obtained reaction solution was purified with methanol to remove unreacted impurities, and further subjected to vacuum drying for 24 hours to obtain compound (B-1). The acid value of the obtained compound (B-1) was 103 mgKOH/g.

(Synthesis Example 2: Compound (B-2))

In the reaction solution in a nitrogen atmosphere, 164 g of carbitol acetate, 287 g of EOCN-103S (manufactured by Nippon Kayaku Co., Ltd.), 96 g of AA, 2 g of 2,6-di -Tertiary butyl-p-cresol and 2 g of triphenylphosphine are reacted at a temperature of 98°C until the acid value of the reaction liquid becomes 0.5 mgKOH/g or less to obtain an epoxy carboxylate compound. Then, 57 g of carbitol acetate and 137 g of tetrahydrophthalic anhydride were fed into the reaction liquid, and the reaction was carried out at a temperature of 95° C. for 4 hours to obtain a compound (B-2). The acid value of the obtained compound (B-2) was 97 mgKOH/g.

(Synthesis Example 3: Compound (B-3))

In a reaction vessel in a nitrogen atmosphere, 123g of RE-310S (manufactured by Nippon Kayaku Co., Ltd.), 47g of AA, 0.3g of hydroquinone monomethyl ether and 0.5g of triphenylphosphine were fed into the reaction vessel at 98°C. The reaction was allowed to proceed at a temperature of 1500 until the acid value of the reaction liquid became 0.5 mgKOH/g or less to obtain an epoxy carboxylate compound. Thereafter, 252 g of carbitol acetate, 89 g of 2,2-bis(dimethylol)-propionic acid, 0.4 g of 2-methylhydroquinone, and 47 g of spiroglycol were added to the The reaction solution was heated to a temperature of 45°C. 162 g of trimethylhexamethylene diisocyanate was slowly dropped onto the solution so that the reaction temperature did not exceed 65°C. After completion of the dropping, the reaction temperature was raised to 80°C, and the absorption at around 2250 cm ^{-1 after} 6 hours of reaction was eliminated by infrared absorption spectrometry to obtain compound (B-3). The acid value of the obtained compound (B-3) was 80.0 mgKOH/g.

[Photopolymerization initiator (C)]

IRGACURE (registered trademark) OXE01 (manufactured by Ciba Japan Co., Ltd., oxime-based compound) (hereinafter referred to as OXE01)

IRGACURE (registered trademark) 369 (manufactured by Ciba Co., Ltd., α-aminoalkylphenone compound) (hereinafter referred to as IC369).

[Thermosetting resin (E)]

Epoxy resin (E-1): manufactured by Mitsubishi Chemical Corporation, JER (registered trademark) 828 (epoxy equivalent 188)

Epoxy resin (E-2): (Stock) ADEKA product, Adeka Resin (registered trademark) EPR-4030 (epoxy equivalent 380)

Epoxy resin (E-3): manufactured by Mitsubishi Chemical Corporation, JER (registered trademark) 1002 (epoxy equivalent 650).

[Example 1]

Put 10.0g of compound (B-1), 0.50g of OXE01, 5.0g of DMEA, and 0.5g of 2-hydroxypyridine into a 100mL clean bottle, and use a rotation-revolution vacuum mixer "Defoaming Nintaro" "ARE-310 (registered trademark; manufactured by Thinky) was mixed to obtain 16.0 g of a resin solution (solid content 68.8% by mass).

The obtained 16.0 g of the resin solution and 62.3 g of Ag particles were mixed and kneaded using a three-roll mill (EXAKT M-50; manufactured by EXAKT) to obtain 78.3 g of photosensitive conductive paste. Table 1 shows the composition of the photosensitive conductive paste.

Using the obtained photosensitive conductive paste, the patternability, linearity, and specific resistance of the conductive pattern were evaluated. The value of developable L/S, which is an evaluation index of patternability, was 15/15, and it was confirmed that good patterning was performed. In addition, the length of the protrusion of the conductive pattern was 2.7 μm, and it was confirmed that the straightness was "good". Further, the specific resistance of the conductive pattern is 6.0×10 ^-5 Ωcm. The evaluation results are shown in Table 2.

[Examples 2~11]

A photosensitive conductive paste having the composition shown in Table 1 was produced in the same manner as in Example 1, and evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Examples 1~2]

The photosensitive conductive paste of the composition shown in Table 1 was produced by the same method as Example 1, and it evaluated similarly to Example 1. The evaluation results are shown in Table 2.

As shown in Table 2, any of the photosensitive conductive pastes of Examples 1 to 11 can produce conductive patterns with excellent patternability, linearity, and conductivity. On the other hand, the photosensitive conductive pastes of Comparative Examples 1 and 2 could not produce a conductive pattern with excellent linearity, and had high specific resistance.

Industrial availability

The photosensitive conductive paste of the present invention can be suitably used to manufacture conductive patterns such as peripheral wiring for touch panels.

Claims (8)

A photosensitive conductive paste containing: conductive particles (A), a compound having an unsaturated double bond (B), a photoradical polymerization initiator (C), and a compound having a hydroxypyridine skeleton in one molecule (D ). The photosensitive conductive paste of claim 1, wherein the compound (D) having a hydroxypyridine skeleton in one molecule has a methylol group. The photosensitive conductive paste of claim 1 or 2, wherein the content of the compound (D) having a hydroxypyridine skeleton in one molecule relative to 100 parts by mass of the compound (B) having an unsaturated double bond is 0.3-10 Mass parts. Such as the photosensitive conductive paste of claim 1 or 2, which further contains a thermosetting resin (E). Such as the photosensitive conductive paste of claim 3, which further contains a thermosetting resin (E). The photosensitive conductive paste of claim 4, wherein the thermosetting resin (E) is an epoxy resin with an epoxy equivalent of 150 to 500 g/equivalent. The photosensitive conductive paste of claim 5, wherein the thermosetting resin (E) is an epoxy resin with an epoxy equivalent of 150 to 500 g/equivalent. A method for manufacturing a substrate with a conductive pattern, which comprises applying the photosensitive conductive paste according to any one of claims 1 to 7 on the substrate and then curing it at a temperature of 100 to 300°C.

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