CN113412688A

CN113412688A - Method for manufacturing conductive pattern

Info

Publication number: CN113412688A
Application number: CN202080013564.2A
Authority: CN
Inventors: 儿玉年矢
Original assignee: Toray Industries Inc
Current assignee: Toray Industries Inc
Priority date: 2019-03-29
Filing date: 2020-03-02
Publication date: 2021-09-17
Also published as: JP7371620B2; TW202043296A; JPWO2020202969A1; KR20210144666A; WO2020202969A1

Abstract

The present invention provides a method for manufacturing a conductive pattern having excellent conductivity even at a low temperature of 100 ℃. Provided is a method for manufacturing a conductive pattern, which comprises the following steps: (1) a step of forming a pattern comprising conductive particles (a) and a resin (b) on a substrate, and (2) a step of bringing an acidic aqueous solution having a pH of 1.2 to 3.5 at 25 ℃ into contact with the formed pattern, wherein the acidic aqueous solution comprises at least 1 salt having an acid dissociation constant (pKa) of 1.0 or less of a conjugate acid of an anion at 25 ℃.

Description

Method for manufacturing conductive pattern

Technical Field

The present invention relates to a method for manufacturing a conductive pattern.

Background

In recent years, a touch panel has been widely used as an input means. The touch panel includes a display unit such as a liquid crystal panel or an organic EL (Electroluminescence) panel, a touch sensor for detecting information input to a specific position, and the like. The touch panel system is roughly classified into a resistive type, a capacitive type, an optical type, an electromagnetic induction type, an ultrasonic type, and the like according to a method of detecting an input position. Among them, a capacitive touch panel is widely used for reasons such as optical brightness, excellent design, simple structure, and excellent functionality.

The capacitive touch sensor has a second electrode orthogonal to the first electrode with an insulating layer interposed therebetween, and outputs a contact position, which is obtained by applying a voltage to an electrode on a touch panel surface and detecting a change in capacitance when a finger or other conductor is touched, as a signal. As a wiring electrode used in a capacitive touch sensor, a transparent wiring electrode such as indium tin oxide is generally used from the viewpoint of making the wiring electrode less visible, but in recent years, an opaque wiring electrode using a metal material has been spreading due to high sensitivity and large screen size. In order to improve the high definition, the thin film thickness, and the visibility of the touch sensor, it is required that the opaque wiring electrode is formed directly on a display portion such as a liquid crystal panel or an organic EL panel. Therefore, it is necessary to form a conductive pattern at a low temperature in addition to forming a pattern. Therefore, as a technique for forming a conductive pattern exhibiting conductivity under low-temperature curing conditions, a conductive paste containing a conductive filler, a zwitterionic compound, and a thermosetting compound has been proposed (for example, see patent document 1). As a technique for reducing the electrical resistance of the conductive pattern layer, there has been proposed a method of bringing the conductive pattern layer into contact with a strong acid aqueous solution at room temperature, a weak acid aqueous solution at a temperature higher than room temperature, and forming a connection in which at least a part of the metal particles in the conductive pattern layer are fused to lower the surface resistivity of the conductive pattern layer (see, for example, patent document 2).

Documents of the prior art

Patent document

Patent document 1: international publication No. 2014/208445

Patent document 2: japanese patent laid-open publication No. 2012-15143

Disclosure of Invention

Problems to be solved by the invention

Although the techniques of patent documents 1 to 2 can exhibit conductivity at a lower temperature than conventional ones, in recent years, conductivity at a lower temperature has been required, and there is a problem that conductivity is insufficient even under a low temperature condition of 100 ℃.

In view of the foregoing problems, an object of the present invention is to provide a method for producing a conductive pattern having excellent conductivity even at a low temperature of 100 ℃.

Means for solving the problems

The present invention relates to a method for manufacturing a conductive pattern, which comprises the following steps:

(1) a step of forming a pattern containing conductive particles (a) and a resin (b) on a base material, and

(2) and a step of bringing an acidic aqueous solution having a pH of 1.2 to 3.5 at 25 ℃ into contact with the formed pattern, the acidic aqueous solution containing at least one salt having an acid dissociation constant (pKa) of 1.0 or less of a conjugate acid of an anion at 25 ℃.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a conductive pattern having excellent conductivity even at a low temperature of 100 ℃ or lower can be formed.

Drawings

Fig. 1 is a schematic view of a light-transmitting pattern of a photomask used for evaluation of conductivity in the example.

Detailed Description

The method for manufacturing a conductive pattern of the present invention comprises the steps of:

(1) a step of forming a pattern including conductive particles (a) and a resin (b) on a substrate (hereinafter, sometimes referred to as step (1)); and

(2) and a step (hereinafter, sometimes referred to as step (2)) of bringing an acidic aqueous solution having a pH of 1.2 to 3.5 at 25 ℃ into contact with the formed pattern, the acidic aqueous solution containing at least one salt having an acid dissociation constant (pKa) of 1.0 or less of a conjugate acid of an anion at 25 ℃.

The conductive pattern obtained by the production method of the present invention is a composite of an organic component of the resin (b) and an inorganic component of the conductive particles (a), and the conductive particles (a) are brought into contact with each other by an atomic diffusion phenomenon, thereby exhibiting conductivity. The resin (b) serves as a binder to improve the adhesion between the pattern and the substrate. The pattern is brought into contact with an acidic aqueous solution containing at least one salt having a conjugate acid of an anion with a dissociation constant (pKa) of 1.0 or less at 25 ℃ and having a pH of 1.2 to 3.5 at 25 ℃, whereby diffusion of atoms from the surface of the conductive particles is promoted, and the conductivity can be improved even at a low temperature of 100 ℃ or less.

First, the step (1) will be explained.

Examples of the substrate include a polyester film such as a polyethylene terephthalate (hereinafter, sometimes referred to as "PET") film, a polyimide film, an aramid film, an epoxy resin film, a polyetherimide film, a polyether ketone film, a polysulfone-based film, a glass substrate, a silicon wafer, an alumina substrate, an aluminum nitride substrate, a silicon carbide substrate, a substrate having a decorative layer formed thereon, a substrate having an insulating layer formed thereon, and the like.

The pattern formed in step (1) contains conductive particles (a). Examples of the conductive particles (a) include particles of silver, gold, copper, platinum, lead, tin, nickel, aluminum, tungsten, molybdenum, chromium, titanium, indium, and alloys of these metals. It may contain 2 or more of them. Among these, particles of a metal selected from silver, gold, and copper are preferable from the viewpoint of conductivity, and silver particles are more preferable from the viewpoint of cost and stability.

The conductive particles (a) may have a layer structure of two or more layers. For example, it may have a core-shell structure having a shell formed of silver on the surface of a core formed of copper. The conductive particles (a) may have surfaces coated with an organic component, an inorganic oxide, or the like. The organic component functions as a dispersant or a conductive aid for conductive particles having a small particle diameter. Examples of the organic component include fatty acids, amines, thiols, and cyanides.

The volume average particle diameter of the conductive particles (a) is preferably 0.1 μm or more from the viewpoint of appropriately suppressing the interaction between the particles and improving the dispersibility of the conductive particles (a) in the pattern. On the other hand, the volume average particle diameter of the conductive particles (a) is preferably 2.0 μm or less from the viewpoint of improving the surface smoothness and dimensional accuracy of the conductive pattern and forming a fine conductive pattern. Here, the volume average particle diameter of the conductive particles (a) can be determined by the following method: the formed pattern is dissolved using a solvent such as THF (tetrahydrofuran) which can dissolve the resin component, and the resulting solution is centrifuged to precipitate the solid component from which the resin component has been removed and recover the solid component. Next, the collected solid component is observed by a Scanning Electron Microscope (SEM) or a Transmission Electron Microscope (TEM) for the conductive particles (a), and primary particles of 100 conductive particles (a) are randomly selected to obtain an image, and the diameter when converted into a circle is obtained by image analysis for each primary particle, and the average diameter weighted by volume is calculated.

The content of the conductive particles (a) in the pattern is preferably 65 to 90 mass%. When the content of the conductive particles (a) is 65 mass% or more, the probability of contact between the conductive particles (a) in the step (2) described later is increased, and the conductivity can be further improved. On the other hand, when the content of the conductive particles (a) is 90% by weight or less, a fine pattern can be formed by photolithography. Here, the proportion of the conductive particles (a) in the conductive pattern can be determined by the following method: the formed pattern was scraped off, the organic component was burned at 400 to 600 ℃ by TG-DTA (differential thermobalance) to determine the ratio of the inorganic solid component in the conductive pattern, and the remaining inorganic solid component was dissolved in nitric acid or the like to perform ICP emission spectroscopy, thereby measuring the ratio of the conductive particles (a) in the inorganic solid component.

The pattern formed in step (1) contains a resin (b). Examples of the resin include acrylic resins, polyester resins, phenol resins, epoxy resins, acrylic urethane resins, polyether urethane resins, phenoxy resins, polycarbonate resins, polyimide resins, polyamide resins, and polyamideimide resins. It may contain 2 or more of them.

When the pattern formation in step (1) is performed by photolithography, the resin (b) preferably has a carboxyl group, and a photosensitive paste described later is preferably used.

Examples of the resin having a carboxyl group include an acrylic copolymer, a carboxylic acid-modified epoxy resin, a carboxylic acid-modified phenol resin, a polyamic acid, and a carboxylic acid-modified siloxane polymer. It may contain 2 or more of them. Among these, an acrylic copolymer or a carboxylic acid-modified epoxy resin having high ultraviolet transmittance is preferable.

The acrylic copolymer is preferably a copolymer of an acrylic monomer and an unsaturated acid or an acid anhydride thereof, and may be a copolymer with another monomer having an unsaturated double bond.

Examples of the acrylic monomer include: methyl acrylate, ethyl acrylate (hereinafter, sometimes referred to as "EA"), 2-ethylhexyl acrylate, n-butyl acrylate (hereinafter, sometimes referred to as "BA"), isobutyl acrylate, isopropyl acrylate, glycidyl acrylate, butoxytriethylene glycol acrylate, dicyclopentenyl acrylate, 2-hydroxyethyl acrylate, isobornyl acrylate, 2-hydroxypropyl acrylate, isodecyl acrylate, isooctyl acrylate, lauryl acrylate, 2-methoxyethyl acrylate, methoxyethylene glycol acrylate, methoxydiethylene glycol acrylate, octafluoropentyl acrylate, phenoxyethyl acrylate, stearyl acrylate, trifluoroethyl acrylate, aminoethyl acrylate, phenyl acrylate, phenoxyethyl acrylate, 1-naphthyl acrylate, n-butyl acrylate (hereinafter, sometimes referred to as "BA"), isobornyl acrylate, 2-hydroxypropyl acrylate, isodecyl acrylate, isooctyl acrylate, lauryl acrylate, methoxyethyl acrylate, methoxyethylene glycol acrylate, methoxydiethylene glycol acrylate, octafluoropentyl acrylate, phenoxyethyl acrylate, stearyl acrylate, trifluoroethyl acrylate, aminoethyl acrylate, phenyl acrylate, phenoxyethyl acrylate, 1-naphthyl acrylate, n-butyl acrylate, and butyl acrylate, 2-naphthyl acrylate, thiophenol acrylate, benzylmercaptan acrylate, allylated cyclohexyl diacrylate, methoxylated cyclohexyl diacrylate, 1, 4-butanediol diacrylate, 1, 3-butanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene glycol diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate, polypropylene glycol diacrylate, tripropylene glycol diacrylate, trimethylolpropane triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, acrylamide, N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, N-N-butoxymethyl acrylamide, N-ethoxymethyl acrylamide, N-butoxymethyl methacrylate, N-butoxymethyl acrylate, N-methyl acrylate, N-ethyl acrylate, N-butyl acrylate, N-ethyl acrylate, N-butyl acrylate, N-2-butyl acrylate, N-butyl acrylate, N-2-butyl acrylate, N-acrylate, and N-butyl acrylate, N-butyl acrylate, N-butyl acrylate, N-2-butyl acrylate, and N-butyl acrylate, N-2-butyl acrylate, N-acrylate, one, N-2-butyl acrylate, one or one, N-isobutoxymethacrylamide, phenol methacrylate, phenol methacrylamide, gamma-acryloxypropyltrimethoxysilane, N- (2-hydroxyphenyl) acrylamide, N- (3-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) acrylamide, o-hydroxyphenyl acrylate, m-hydroxyphenyl acrylate, p-hydroxyphenyl acrylate, 2- (2-hydroxyphenyl) ethyl acrylate, 2- (3-hydroxyphenyl) ethyl acrylate, 2- (4-hydroxyphenyl) ethyl acrylate, and the like, and compounds obtained by substituting an acryloyl group of the above compounds with a methacryloyl group. Among these, monomers selected from the group consisting of ethyl acrylate, 2-hydroxyethyl acrylate and isobornyl acrylate are particularly preferable. More than 2 of them may be used.

Examples of the unsaturated acid or its anhydride include acrylic acid (hereinafter, sometimes referred to as "AA"), methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetate, and anhydrides thereof. More than 2 of them may be used. The acid value of the acrylic copolymer can be adjusted by the copolymerization ratio of the unsaturated acid.

Examples of the other monomer having an unsaturated double bond include: o-hydroxystyrene, m-hydroxystyrene, p-hydroxystyrene, and the like. More than 2 of them may be used.

The carboxylic acid-modified epoxy resin is preferably a reaction product of an epoxy compound and an unsaturated acid or an unsaturated acid anhydride. The carboxylic acid-modified epoxy resin is obtained by modifying an epoxy group of an epoxy compound with a carboxylic acid or a carboxylic acid anhydride, and does not contain an epoxy group.

Examples of the epoxy compound include: glycidyl ethers, glycidyl amines, epoxy resins, and the like. More specifically, examples of the glycidyl ethers include: 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 diglycidyl ether, hydrogenated bisphenol a diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, bisphenol fluorene diglycidyl ether, bisphenol diglycidyl ether, tetramethylbisphenol glycidyl ether, trimethylolpropane triglycidyl ether, 3 ', 4' -epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate, and the like. Examples of the glycidyl amine include tert-butyl glycidyl amine. Examples of the epoxy resin include bisphenol a type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin, Novolac type epoxy resin, hydrogenated bisphenol a type epoxy resin, and the like. More than 2 of them may be used.

Examples of the unsaturated acid or unsaturated acid anhydride include those exemplified as the raw material of the acrylic copolymer.

Unsaturated double bonds can be introduced by reacting a compound having an unsaturated double bond such as glycidyl (meth) acrylate with the acrylic copolymer and the carboxylic acid-modified epoxy resin. By introducing an unsaturated double bond into the resin (b), the crosslinking density of the exposed portion can be increased during exposure, the development margin can be increased, and a fine pattern can be formed.

As the resin (b), a resin having a phenolic hydroxyl group can also be preferably used. By providing the phenolic hydroxyl group to the resin (b), a hydrogen bond can be formed with a polar group such as a hydroxyl group or an amino group on the surface of the substrate, and the adhesion between the pattern and the substrate can be improved.

The acid value of the resin (b) is preferably 50 to 250 mgKOH/g. When the acid value is 50mgKOH/g or more, the solubility in the developer increases, and the occurrence of development residue can be suppressed. The acid value is more preferably 60mgKOH/g or more. On the other hand, when the acid value is 250mgKOH/g or less, excessive dissolution in a developer can be suppressed, and film damage of a pattern can be suppressed. The acid value is more preferably 200mgKOH/g or less. The acid value of the resin (b) can be measured in accordance with JIS K0070 (1992).

Examples of the method of forming the pattern include a method of forming a pattern by printing a paste containing the conductive particles (a) and the resin (b) and, if necessary, other components by screen printing, gravure printing, flexo printing, inkjet printing, or the like, a method of forming a pattern by photolithography having exposure and development steps, and the like. Examples of the method of forming a pattern by photolithography include: a method of forming a pattern by applying a photosensitive resist on a non-photosensitive paste coating film, and performing the steps of exposure, development, etching, and removal of the resist; and a method of directly forming a pattern from the photosensitive paste coating film through exposure and development steps. Among them, a method of forming a pattern from a photosensitive paste coating film by photolithography having exposure and development steps is preferable from the viewpoint of thinning of the pattern and shortening of the number of manufacturing steps.

The content of the conductive particles (a) in the paste is preferably 65 to 90 wt% in the solid content.

The method for forming a conductive pattern of the present invention preferably includes the following photolithography steps: a photosensitive paste containing conductive particles (a), a carboxyl group-containing resin (B) (also referred to as a carboxyl group-containing resin (B)), a reactive monomer (c) having an unsaturated double bond, and a photopolymerization initiator (d) is applied onto a substrate to form a coating film, and the coating film is exposed and developed to form a pattern. By forming the conductive pattern in this manner, a fine pattern can be easily formed by a simple method.

Examples of the carboxyl group-containing resin (B) include the above-mentioned resins (B) having a carboxyl group. It may contain 2 or more of them.

The acid value of the carboxyl group-containing resin (B) can be adjusted to a desired range by the proportion of the unsaturated acid in the constituent components, for example, in the case of an acrylic copolymer. In the case of a carboxylic acid-modified epoxy resin, the range can be adjusted to a desired range by reacting a polybasic acid anhydride. In the case of the carboxylic acid-modified phenol resin, the ratio of the polybasic acid anhydride in the constituent components can be adjusted to a desired range.

Examples of the reactive monomer (c) having an unsaturated double bond include the acrylic monomers exemplified above as raw materials of the acrylic copolymer, styrene (hereinafter referred to as "(St)"), and the like. It may contain 2 or more of them.

When the paste used in the step (1) contains an acrylic copolymer and a reactive monomer (c) having an unsaturated double bond, the content of the reactive monomer (c) having an unsaturated double bond in the paste is preferably 1 to 100 parts by weight based on 100 parts by weight of the acrylic copolymer. By containing 1 part by weight or more of the reactive monomer (c) having an unsaturated double bond, a fine pattern can be formed. On the other hand, by containing 100 parts by weight or less of the reactive monomer (c) having an unsaturated double bond, curing shrinkage can be appropriately suppressed, and conductivity can be further improved.

The photopolymerization initiator (e) is a compound that absorbs short-wavelength light such as ultraviolet light to decompose or to undergo a hydrogen abstraction reaction to generate radicals. Examples of the photopolymerization initiator (e) include benzophenone derivatives, acetophenone derivatives, thioxanthone derivatives, benzil derivatives, benzoin derivatives, oxime compounds, α -hydroxyketone compounds, α -aminoalkylbenzophenone compounds, phosphine oxide compounds, anthrone compounds, anthraquinone compounds, and the like. Examples of the benzophenone derivative include benzophenone, methyl o-benzoylbenzoate, 4 '-bis (dimethylamino) benzophenone, 4' -bis (diethylamino) benzophenone, 4 '-dichlorobenzophenone, fluorenone, and 4-benzoyl-4' -methylbenzophenone. Examples of the acetophenone derivatives include p-tert-butyl dichloroacetophenone, 4-azidobenzylideneacetophenone, and 2, 2' -diethoxyacetophenone. Examples of the thioxanthone derivative include thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, and diethylthioxanthone. Examples of the benzil derivative include benzil, benzil dimethyl ketal, and benzyl- β -methoxyethyl acetal. Examples of the benzoin derivative include benzoin, benzoin methyl ether, benzoin butyl ether, and the like. Examples of the oxime-based compound include 1, 2-octanedione-1- [4- (phenylthio) -2- (o-benzoyloxime) ], ethanone-1- [ 9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] -1- (o-acetyloxime), 1-phenyl-1, 2-butanedione-2- (o-methoxycarbonyl) oxime, 1-phenyl-propanedione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-propanedione-2- (o-benzoyl) oxime, 1, 3-diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoyl) oxime, and the like. Examples of the α -hydroxyketone compound include 2-hydroxy-2-methyl-1-phenyl-propan-1-one and 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl-1-propan-1-one. Examples of the α -aminoalkylphenone-based compound include 2-methyl- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, and 2-dimethylamino-2- (4-methylbenzyl) -1- (4-morpholin-4-yl-phenyl) -butan-1-one. Examples of the phosphine oxide compound include 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide and bis (2,4, 6-trimethylbenzoyl) -phenylphosphine oxide. Examples of the anthrone compound include anthrone, benzanthrone, dibenzosuberone and methyleneanthrone. Examples of the anthraquinone compound include anthraquinone, 2-tert-butylanthraquinone, 2-amylanthraquinone, and β -chloroanthraquinone. It may contain 2 or more of them. Among these, oxime compounds having high photosensitivity are preferable.

The content of the photopolymerization initiator (d) in the photosensitive paste is preferably 1 to 30 parts by weight based on 100 parts by weight of the carboxyl group-containing resin (B). When the content of the photopolymerization initiator (d) is 1 part by weight or more, the curing density of the exposed portion can be increased, and the residual film ratio after development can be increased. On the other hand, if the content of the photopolymerization initiator (d) is 30 parts by weight or less, excessive light absorption by the photopolymerization initiator (d) in the upper portion of the pattern can be suppressed. As a result, the pattern can be easily tapered, and adhesion to the substrate can be improved.

In addition to the above, additives such as a solvent, a plasticizer, a leveling agent, a surfactant, a silane coupling agent, an antifoaming agent, and a pigment may be added to the paste used for forming a pattern.

Specific examples of the plasticizer include: dibutyl phthalate, dioctyl phthalate, polyethylene glycol, glycerol, and the like. Specific examples of the leveling agent include a specific vinyl polymer and a specific acrylic polymer.

Examples of the silane coupling agent include methyltrimethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, hexamethyldisilazane, 3-methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltrimethoxysilane, and 3-glycidoxypropylmethyldiethoxysilane.

Examples of the solvent include N, N-dimethylacetamide, N-dimethylformamide, N-methyl-2-pyrrolidone, 2-dimethylethanolamine: (DMEA)', dimethylimidazolidinone, dimethyl sulfoxide, 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, diethylene glycol monobutyl ether, diethylene glycol, 2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, and the like. It may contain 2 or more of them. The boiling point of the solvent is preferably 150 ℃ or higher. When the boiling point is 150 ℃ or higher, volatilization of the solvent is suppressed, and thickening of the paste can be suppressed.

The step (1) will be described in more detail by taking as an example a method of forming a pattern from a photosensitive paste coating film by photolithography.

First, conductive particles (a), a resin (b), a solvent, and other components as necessary are mixed to prepare a paste. Examples of the mixing device include a disperser such as a three-roll mill, a ball mill, and a planetary ball mill, and a kneader.

Next, the obtained paste was applied to a substrate and dried. Examples of the paste coating method include spin coating using a spin coater, spray coating, roll coating, screen printing, coating using a blade coater, die coater, roll coater, meniscus coater, or bar coater. Examples of the drying method include heating drying by an oven, a hot plate, infrared rays, or the like, and vacuum drying. The drying temperature is preferably 50-180 ℃, and the drying time is preferably 1 minute-several hours.

Next, the obtained coating film is exposed to light through an arbitrary pattern forming mask to form a latent image. As a light source for exposure, i-line (365nm), h-line (405nm) or g-line (436nm) of a mercury lamp is preferably used.

After exposure, the unexposed portions are dissolved and removed by development using a developer, thereby forming a desired pattern. Examples of the developer used in the alkali development include aqueous solutions of tetramethylammonium hydroxide, diethanolamine, diethylaminoethanol, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, diethylamine, methylamine, dimethylamine, dimethylaminoethyl acetate, dimethylethanolamine, dimethylaminoethyl methacrylate, cyclohexylamine, ethylenediamine, hexamethylenediamine, and the like. More than 2 of them may be used. In addition, 1 or more of the following substances may be added to these aqueous solutions as the case may be: polar solvents such as N-methyl-2-pyrrolidone, N-dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, γ -butyrolactone, and the like; alcohols such as methanol, ethanol, and isopropanol; esters such as ethyl lactate and propylene glycol monomethyl ether acetate; ketones such as cyclopentanone, cyclohexanone, isobutyl ketone, and methyl isobutyl ketone; surfactants, and the like.

Examples of the developing method include: a method of spraying a developing solution onto a coating film surface while leaving the base material having the paste coating film exposed still or rotating; a method of immersing the substrate having the paste coating film exposed to light in a developing solution; a method of applying ultrasonic waves while immersing the substrate having the exposed paste coating film in a developing solution.

After development, a rinse treatment based on a rinse solution may be performed. Examples of the eluent include water, or an aqueous solution obtained by adding an alcohol such as ethanol or isopropyl alcohol, or an ester such as ethyl lactate or propylene glycol monomethyl ether acetate to water.

The thickness of the pattern obtained in step (1) is preferably 3 μm or less. By setting the thickness to 3 μm or less, a fine conductive pattern can be formed. In addition, the acidic aqueous solution is easily penetrated, and further excellent conductivity can be obtained even in a short time.

Next, the step (2) will be explained.

In the step (2), the pattern formed in the step (1) is brought into contact with an acidic aqueous solution having a pH of 1.2 to 3.5 at 25 ℃, the acidic aqueous solution containing at least 1 salt having an acid dissociation constant (pKa) of 1.0 or less of a conjugate acid of an anion at 25 ℃.

The acidic aqueous solution contains at least 1 kind of salt having an acid dissociation constant (pKa) of 1.0 or less of a conjugate acid of an anion at 25 ℃. The term "salt" as used herein means a component composed of a cation other than a proton and an anion, and in the present invention, the term "salt" also includes a substance ionized into a cation and an anion in an aqueous solution. Further, the cation may exist in the form of an ion partially bonded to a hydroxyl group, and the aqueous solution in this case may become acidic. The anion contained in the salt is present in the acid aqueous solution, whereby diffusion of atoms from the surface of the conductive particle (a) is promoted, and the conductivity is improved. By causing cations other than protons contained in the salt to be present in the acid aqueous solution, the concentration of anions can be increased even if the pH is 1.2 or more, as described later. As a result, a decrease in conductivity due to corrosion of the conductive particles (a) contained in the conductive pattern can be suppressed. When the pKa of the conjugate acid of the anion contained in the salt at 25 ℃ is 1.0 or less, the diffusion of atoms of the conductive particles is promoted, and the conductivity can be improved. The pKa of the conjugate acid of the anion contained in the salt at 25 ℃ is more preferably-5.0 or less. The pKa of the conjugate acid of the anion contained in the salt at 25 ℃ can be determined and the conjugate acid can be measured by an absorptiometry method after the anion contained in the salt is determined. When the conjugate acid of the anion contained in the salt has a pKa of-2 or less, reference may be made to literature values and the like.

The salt having a conjugate acid of an anion at 25 ℃ and a pKa of 1.0 or less is not particularly limited as long as it is water-soluble, and examples thereof include sodium nitrate, potassium nitrate, sodium chloride, potassium chloride, nickel (II) chloride, iron (III) chloride, tin (II) chloride, copper (II) chloride, sodium bromide, potassium bromide, nickel (II) bromide, iron (III) bromide, copper (II) bromide, sodium iodide, potassium iodide, nickel (II) iodide, sodium hydrogensulfate, potassium hydrogensulfate, sodium benzenesulfonate, potassium benzenesulfonate, sodium trifluoroacetate, potassium trifluoroacetate, and the like. It may contain 2 or more of them.

The salt concentration is preferably 0.05mol/L or more. By setting the salt concentration to 0.05mol/L or more, diffusion of atoms from the surface of the conductive particles (a) is promoted, and the conductivity can be further improved. Here, when 2 or more salts are contained, "the concentration of the salt" refers to the total concentration of the salts.

The kind and concentration of the salt having a pKa of 1.0 or less of the conjugate acid of the anion at 25 ℃ contained in the acidic aqueous solution can be analyzed by ion chromatography, inductively coupled plasma mass spectrometry, or the like.

The pH of the acidic aqueous solution at 25 ℃ is 1.2 to 3.5. By setting the pH to 1.2 or more, a decrease in conductivity due to corrosion of the conductive particles (a) contained in the conductive pattern can be suppressed. On the other hand, when the pH is 3.5 or less, diffusion of atoms from the surface of the conductive particles (a) can be promoted, and the conductivity can be improved. The pH is more preferably 2.5 or less. The pH was measured by the glass electrode method from the potential difference generated between 2 electrodes, the glass electrode and the comparative electrode.

In the acidic aqueous solution, an acid may be contained as a component other than the above salt so as to have a predetermined pH range. The acid preferably contains an acid having an acid dissociation constant (pKa) of 2 to 5 at 25 ℃, that is, a weak acid. When the polybasic acid is contained, the pKa of the most easily ionized 1 st stage is preferably 2 to 5, and when the polybasic acid is contained in 2 or more types, the pKa of the most easily ionized acid is preferably 2 to 5. By using a weak acid having a pKa of 2 or more, long-term reliability due to the acid remaining in the conductive pattern can be improved. On the other hand, by setting the pKa to 5 or less, the conductivity can be further improved. The pKa is more preferably 3.5 or less.

Examples of the acid having a pKa of 2 to 5 at 25 ℃ include phosphoric acid, citric acid, acetic acid, propionic acid, ascorbic acid, formic acid, lactic acid, and the like. The acid can be determined by analysis, and the pKa can be determined using absorptiometry for the acid. Acid HX is formed by reacting HX and X in aqueous solution^-The two states exist, can be formed by HX and X^-Measuring the difference between HX and X in an aqueous solution^-And can be calculated based on the following numerical formula (1).

[ mathematical formula 1]

The concentration of the acid having a pKa of 2 to 5 at 25 ℃ is preferably 0.05 to 1 mol/L. By setting the concentration to 0.05mol/L, the conductivity can be further improved in a short time. On the other hand, by setting the concentration to 1mol/L or less, the acid is less likely to remain in the wiring, and the reliability can be improved. The concentration may be adjusted appropriately so as to have a desired pH according to the kind of the acid to be contained.

In the step (2), the temperature of the acidic aqueous solution in contact with the pattern is preferably 40 to 90 ℃. By setting the liquid temperature to 40 ℃ or higher, the conductivity can be improved in a shorter time. The liquid temperature is more preferably 60 ℃ or higher. On the other hand, evaporation of the acidic aqueous solution can be suppressed by setting the liquid temperature to 90 ℃ or lower. The liquid temperature of the acidic aqueous solution can be appropriately adjusted depending on the type of the acid contained therein.

In the step (2), the acidic aqueous solution may be heated in advance to be in contact with the pattern, or may be heated in a state where the pattern is in contact with the acidic aqueous solution. Examples of the heating method include heating with a hot plate, a hot air oven, an inert oven, an IR oven, a microwave, or the like; xenon flash, etc.

The concentration of the acidic aqueous solution is preferably 0.05-1 mol/L. By setting the concentration to 0.05mol/L, the conductivity can be further improved in a short time. On the other hand, by setting the concentration to 1mol/L or less, acid is less likely to remain in the wiring, and reliability can be improved. The concentration may be appropriately adjusted so as to have a desired pH according to the type of acid contained.

The conductive pattern obtained in step (2) may be subjected to rinsing treatment with a rinsing liquid. Examples of the eluent include water, or an aqueous solution obtained by adding an alcohol such as ethanol or isopropanol, or an ester such as ethyl lactate or propylene glycol monomethyl ether acetate to water. By performing the rinsing treatment, the residual acid can be washed away, and the long-term reliability of the wiring can be improved.

Examples

The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

The materials used in the examples and comparative examples are as follows.

[ conductive particles (a) ]

Silver particles having a volume average particle diameter of 0.3 μm

[ reactive monomer (c) having an unsaturated double bond ]

Light acrylate BP-4EA (acrylic monomer; manufactured by Kyoeisha chemical Co., Ltd.).

(Synthesis example 1)

5 parts by mass of glycidyl methacrylate (hereinafter, sometimes referred to as "GMA") and EA/2-ethylhexyl methacrylate (hereinafter, sometimes referred to as "2-EHMA")/an acrylic copolymer of styrene/acrylic acid (copolymerization ratio (parts by mass): 20/40/20/15)

150g of DMEA described later was charged into a reaction vessel under a nitrogen atmosphere, and the temperature was raised to 80 ℃ using an oil bath. A mixture comprising 20g of EA, 40g of 2-EHMA, 20g of St, 15g of AA, 0.8g of 2, 2' -azobisisobutyronitrile and 10g of DMEA was added dropwise thereto over a period of 1 hour. After the completion of the dropwise addition, the polymerization reaction was further carried out for 6 hours. Thereafter, 1g of hydroquinone monomethyl ether was added to stop the polymerization reaction. Next, a mixture containing 5g of GMA, 1g of triethylbenzylammonium chloride and 10g of DMEA was added dropwise over a period of 0.5 hours. After the completion of the dropwise addition, the addition reaction was further carried out for 2 hours. The obtained reaction solution was purified with methanol to thereby remove unreacted impurities, and further dried under vacuum for 24 hours, thereby obtaining an acrylic copolymer (B-1). The acid value of the resulting acrylic copolymer (B-1) was 103 mgKOH/g.

(Synthesis example 2)

An acrylic copolymer (copolymerization ratio (parts by mass): 50/10/15) of 5 parts by mass of GMA and ethylene oxide-modified bisphenol A diacrylate (FA-324A; manufactured by Hitachi chemical Co., Ltd.)/EA/AA

To a nitrogen atmosphere reaction vessel was added 150g of DMEA and an oil bath was used to warm to 80 ℃. To this was added dropwise over 1 hour a mixture comprising 50g of ethylene oxide-modified bisphenol A diacrylate FA-324A, 20g of EA, 15g of AA, 0.8g of 2, 2' -azobisisobutyronitrile and 10g of DMEA. After the completion of the dropwise addition, the polymerization reaction was further carried out for 6 hours. Thereafter, 1g of hydroquinone monomethyl ether was added to stop the polymerization reaction. Next, a mixture containing 5g of GMA, 1g of triethylbenzylammonium chloride and 10g of DMEA was added dropwise over a period of 0.5 hours. After the completion of the dropwise addition, the addition reaction was further carried out for 2 hours. The obtained reaction solution was purified with methanol to thereby remove unreacted impurities, and further dried under vacuum for 24 hours, thereby obtaining an acrylic copolymer (B-2). The acid value of the resulting acrylic copolymer (B-2) was 96 mgKOH/g.

(Synthesis example 3)

EA/2-EHMA/BA/N-methylolacrylamide/AA acrylic copolymer (copolymerization ratio (parts by mass): 20/40/20/5/15)

To a nitrogen atmosphere reaction vessel was added 150g of DMEA and an oil bath was used to warm to 80 ℃. A mixture comprising 20g of EA, 40g of 2-EHMA, 20g of BA, 5g of N-methylolacrylamide, 15g of AA, 0.8g of 2, 2' -azobisisobutyronitrile and 10g of DMEA was added dropwise thereto over 1 hour. After the completion of the dropwise addition, the polymerization reaction was further carried out for 6 hours. Thereafter, 1g of hydroquinone monomethyl ether was added to stop the polymerization reaction. The obtained reaction solution was purified with methanol to thereby remove unreacted impurities, and further dried under vacuum for 24 hours, thereby obtaining an acrylic copolymer (B-3). The acid value of the resulting acrylic copolymer (B-3) was 103 mgKOH/g.

[ photopolymerization initiator (d) ]

"IRGACURE (registered trademark)" OXE01 (trade name, oxime compound manufactured by BASF JAPAN (ltd.)) (hereinafter referred to as OXE 01).

[ solvent ]

DMEA (manufactured by Tokyo chemical industry Co., Ltd.)

The evaluation methods in the examples and comparative examples are shown below.

< determination of pKa >

The pKa of the acid was determined by using a pKa analyzer (Sirius-T3; manufactured by Pion) while adjusting the acid shown in Table 1 to an acidic aqueous solution of 0.01mol/L and maintaining the solution at a temperature of 25 ℃.

The pKa of the conjugate acid of the anion constituting the salt was determined by adjusting an acid containing the anion constituting the salt and a proton to 0.01mol/L, and then maintaining the aqueous solution at a liquid temperature of 25 ℃ using a pKa analyzer (Sirius-T3; manufactured by Pion). When the pKa of the conjugate acid of the anion constituting the salt is-2 or less, reference is made to "David a. evans, [ online ], internet < URL: http:// evans. rc. fas. harvard. edu/pdf/evans _ pKa _ table. pdf > ".

< determination of pH >

The pH of the acidic aqueous solution was measured by using a pH meter (F-71; manufactured by horiba, Ltd.) while maintaining the acidic aqueous solution described in Table 1 at a liquid temperature of 25 ℃.

< evaluation of patterning Property >

The samples for evaluation of patterning properties obtained in each of examples and comparative examples were observed with an optical microscope, and the conductive pattern having the smallest value of the line and space (hereinafter, sometimes referred to as "L/S") in which no residue was present between the patterns and no pattern peeling was observed was confirmed, and the case where the value of L/S was 7/7 was judged as a, the case where the value of L/S was 10/10 was judged as B, the case where the value of L/S was 15/15 was judged as C, and the case where the conductive pattern could not be formed at 15/15 was judged as D. The patterning property was excellent in the order of A > B > C > D, indicating that fine patterning was possible.

< evaluation of conductivity >

The respective ends of the conductivity evaluation samples obtained in the examples and comparative examples were connected to each other by a resistance meter (RM 3544; manufactured by HIOKI) to measure the resistance value, and the specific resistivity was calculated based on the following equation (2). The film thickness can be measured using a stylus height difference meter such as "SURFCOM (registered trademark)" 1400 (manufactured by tokyo co corporation). More specifically, the film thicknesses at 10 randomly selected positions were measured by a stylus height difference meter (measurement length: 1mm, scanning speed: 0.3 mm/sec), and the average value of the film thicknesses was obtained to calculate the film thickness. The line width is calculated as follows: the line widths of the randomly selected 10 positions were observed with an optical microscope, and the image data were analyzed to determine the average value of the line widths.

Specific resistance value x film thickness x line width/line length (2)

The smaller the specific resistance, the more excellent the conductivity.

(example 1)

A100 mL clean bottle was charged with 10.0g of acrylic copolymer (B-1), 2.0g of Light acrylate BP-4EA, 0.60g of OXE01 and 9.0g of DMEA, and the mixture was mixed with "Awatori Rentaro" (ARE-310; manufactured by THINKY corporation) to obtain 21.6g of a resin solution (total solid content: 58.3 mass%).

21.6g of the obtained resin solution and 50.4g of silver particles were mixed and kneaded by using a three-roll mill (EXAKT M-50; manufactured by EXAKT Co., Ltd.) to obtain 72.0g of conductive paste 1.

The conductive paste 1 was coated on a PET film having a thickness of 50 μm by a screen printing method so that the coating film thickness after drying became 1.5 μm, and the obtained coating film was dried in a drying oven at 80 ℃ for 15 minutes. The following patterning properties and electrical conductivity were evaluated.

Patterning property

The dried coating film was exposed and developed using a set of straight lines (i.e., light-transmitting patterns) arranged at a constant L/S as 1 cell through a photomask having 3 types of cells each having a different L/S value, to obtain 3 types of patterns each having a different L/S value. Thereafter, the 3 patterns obtained were immersed in an acidic aqueous solution described in table 1 for a predetermined time, and acid was removed by rinsing with ultrapure water, water was removed by air cut (air cut), and the resultant was dried in a drying oven at 80 ℃ for 3 minutes to obtain 3 kinds of conductive patterns having different L/S values, which were used as samples for evaluation of patterning properties. The L/S values of the cells included in the photomask were 15/15, 10/10, and 7/7 (each indicating line width (μm)/space (μm)). During the exposure, an exposure apparatus (PEM-6M; manufactured by UNION OPTICAL CO., LTD.) was used to expose 300mJ/cm²(wavelength 365nm conversion) was subjected to full-line exposure, and for development, the substrate was immersed in 0.20 mass% of Na₂CO₃After 30 seconds in the solution, rinsing treatment with ultrapure water was performed. The evaluation results of the patterning property are shown in table 1.

Conductivity of electricity

The dried coating film was exposed to light and developed through a photomask having 100 light-transmitting patterns 100 shown in fig. 1, to obtain a pattern. Then, the obtained pattern was immersed in an acidic aqueous solution described in table 1 for the time period described in table 1, washed to remove acid by rinsing treatment with ultrapure water, removed of water by air cutting, and dried in a drying oven at 80 ℃ for 3 minutes to obtain a sample for evaluation of conductivity. The resulting conductive pattern had a line width of 0.10mm and a line length of 80 mm. The conditions for exposure and development were the same as those described for the preparation of the sample for evaluation of patterning property. The evaluation results of the conductivity are shown in table 1.

(examples 2 to 24 and 26)

A predetermined pattern was formed using the conductive paste having the composition shown in table 1, and a conductive pattern was produced using the acidic aqueous solution shown in table 1 in the same manner as in example 1, and the same evaluation as in example 1 was performed. The results of the evaluation of the patterning property and the conductivity are shown in table 1.

(example 25)

A100 mL clean bottle was charged with 12.0g of the acrylic copolymer (B-2), 0.60g of OXE01 and 9.0g of DMEA, and the mixture was mixed with "Awatori Rentaro" (ARE-310; manufactured by THINKY Co., Ltd.) to obtain 21.6g of a resin solution (total solid content: 58.3 mass%).

21.6g of the obtained resin solution and 50.4g of silver particles were mixed and kneaded by using a three-roll mill (EXAKT M-50; manufactured by EXAKT Co., Ltd.) to obtain 72.0g of conductive paste 2. A predetermined pattern was formed by using the conductive paste 2, and a conductive pattern was produced by the same method as in example 1 using an acidic aqueous solution shown in table 1, and the same evaluation as in example 1 was performed. The results of the evaluation of the patterning property and the conductivity are shown in table 1.

(example 27)

A predetermined pattern was formed using the conductive paste having the composition shown in table 1, and the obtained pattern was immersed in the acidic aqueous solution shown in table 1 for the time shown in table 1, and then cured in a drying oven at 100 ℃ for 10 minutes without cleaning. Thereafter, the acid was washed off by rinsing treatment with ultrapure water, water was removed by air cutting, and the conductive pattern was produced by drying in a drying oven at 80 ℃ for 3 minutes, and the same evaluation as in example 1 was performed. The results of the evaluation of the patterning property and the conductivity are shown in table 1.

(example 28)

10.0g of the acrylic copolymer (B-1) and 8.0g of DMEA were put into a 100mL clean bottle and mixed with "Awatori Rentaro" (ARE-310; manufactured by THINKY Co., Ltd.) to obtain 18.0g of a resin solution (total solid content: 55.6 mass%).

The resin solution thus obtained (18.0 g) and silver particles (90.0 g) were mixed and kneaded by using a three-roll mill (EXAKT M-50, manufactured by EXAKT) to obtain conductive paste 3 (108.0 g).

The conductive paste 3 was gravure-printed on a PET film having a thickness of 50 μm, thereby obtaining 3 kinds of patterns having different L/S values, respectively. The resulting pattern was dried in a drying oven at 80 ℃ for 15 minutes. Thereafter, the 3 patterns obtained were immersed in an acidic aqueous solution described in table 1 for a predetermined time, and acid was removed by rinsing with ultrapure water, water was removed by air-cutting, and the resultant was dried in a drying oven at 80 ℃ for 3 minutes to obtain 3 kinds of conductive patterns having different L/S values, which were used as samples for evaluation of patterning properties. The L/S values of the cells of the intaglio plate used in the intaglio printing are 15/15, 10/10, and 7/7 (each indicates a line width (μm)/space (μm)). The results of evaluation for patterning properties are shown in table 1.

The conductive paste 3 was gravure-printed on a PET film having a thickness of 50 μm, thereby obtaining a pattern for evaluation of conductivity. The intaglio plate used in the intaglio printing has 100 patterns 100 shown in fig. 1. The resulting pattern was dried in a drying oven at 80 ℃ for 15 minutes. Then, the obtained pattern was immersed in an acidic aqueous solution described in table 1 for the time period described in table 1, and acid was removed by rinsing with ultrapure water, water was removed by air-cutting, and the resultant was dried in a drying oven at 80 ℃ for 3 minutes to obtain a sample for evaluation of conductivity. The resulting conductive pattern had a line width of 0.10mm and a line length of 80 mm. The evaluation results for conductivity are shown in table 1.

Comparative examples 1,2, 6 to 9

A predetermined pattern was formed using the conductive paste having the composition shown in table 2, and a conductive pattern was produced using the acidic aqueous solution shown in table 2 in the same manner as in example 1, and the same evaluation as in example 1 was performed. The results of the evaluation of the patterning property and the conductivity are shown in table 2.

Comparative example 3

A predetermined pattern was formed using a conductive paste having the composition shown in table 2, the obtained pattern was immersed in a 0.2mol/L hydrochloric acid aqueous solution at 25 ℃ for 1 minute, then immersed in a 0.2mol/L citric acid aqueous solution heated to 70 ℃ for 5 minutes, washed off with acid by rinsing with ultrapure water, removed with water by air cutting, and dried in a drying oven at 80 ℃ for 3 minutes to produce a conductive pattern, and the same evaluation as in example 1 was performed. The results of the evaluation of the patterning property and the conductivity are shown in table 2.

Comparative example 4

A predetermined pattern was formed using a conductive paste having the composition shown in table 2, the obtained pattern was immersed in a 0.2mol/L hydrochloric acid aqueous solution at 25 ℃ for 1 minute, then immersed in a 0.2mol/L citric acid aqueous solution heated to 70 ℃ for 10 minutes, washed off with acid by rinsing with ultrapure water, removed with water by air cutting, and dried in a drying oven at 80 ℃ for 3 minutes to produce a conductive pattern, and the same evaluation as in example 1 was performed. The results of the evaluation of the patterning property and the conductivity are shown in table 2.

Comparative example 5

A predetermined pattern was formed using a conductive paste having the composition shown in table 2, the obtained pattern was immersed in a 1mol/L hydrochloric acid aqueous solution at 25 ℃ for 1 minute, then immersed in a 1mol/L citric acid aqueous solution heated to 70 ℃ for 10 minutes, washed off with acid by rinsing with ultrapure water, removed with water by air cutting, and dried in a drying oven at 80 ℃ for 3 minutes to produce a conductive pattern, and the same evaluation as in example 1 was performed. The results of the evaluation of the patterning property and the conductivity are shown in table 2.

Comparative example 10

A predetermined pattern was formed using a conductive paste having the composition shown in table 2, and the obtained pattern was cured in a drying oven at 100 ℃ for 1 hour without being immersed in an acidic aqueous solution to produce a conductive pattern, and the same evaluation as in example 1 was performed. The results of the evaluation of the patterning property and the conductivity are shown in table 2.

[ Table 1]

[ Table 2]

Description of the reference numerals

100 light transmission pattern

Claims

1. A method for manufacturing a conductive pattern, comprising the steps of:

2. The method for producing a conductive pattern according to claim 1, wherein a concentration of the salt contained in the acidic aqueous solution is 0.05mol/L or more.

3. The method for producing a conductive pattern according to claim 1 or 2, wherein the acidic aqueous solution contains an acid other than the salt and the acid has a pKa of 2 to 5.

4. The method for producing a conductive pattern according to any one of claims 1 to 3, wherein the acidic aqueous solution has a liquid temperature of 40 ℃ to 90 ℃.

5. The method of manufacturing an electrically conductive pattern according to any one of claims 1 to 4, wherein heating is performed in a state where the pattern is in contact with the acidic aqueous solution.

6. The method of producing a conductive pattern according to any one of claims 1 to 5, wherein the step of forming a pattern in (1) is a photolithography step in which a photosensitive paste containing conductive particles (a), a carboxyl group-containing resin (B), a reactive monomer (c) having an unsaturated double bond, and a photopolymerization initiator (d) is applied to a substrate to form a coating film, and the coating film is exposed and developed to form a pattern.

7. The method for producing a conductive pattern according to any one of claims 1 to 6, wherein the conductive particles (a) contain silver particles.

8. The method of manufacturing a conductive pattern according to any one of claims 1 to 7, wherein the thickness of the conductive pattern is 3 μm or less.