Photosensitive conductive paste, method for manufacturing substrate with conductive pattern, method for manufacturing electronic component, cured film, fired body, and electronic component

Abstract

The present invention provides a photosensitive conductive paste which contains conductive particles (A), a photosensitive organic component (B) and two or more solvents (C), wherein: the difference between the boiling points of a solvent (C-1) that has the lowest boiling point and a solvent (C-2) that has the highest boiling point among the solvents (C) is 35°C to 120°C; the boiling point of the solvent (C-2) is 251°C to 300°C; and the amount of the solvent (C-2) relative to 100% by mass of all solvents is 25% by mass to 80% by mass. This photosensitive conductive paste is suppressed in viscosity increase during a coating step; and even in cases where the photosensitive conductive paste is dried at low temperatures, the tack properties of a dried film are suppressed and change with time of the residual solvent amount in the dried film is also suppressed.

Description

[Technical Field]

[0001] The present invention relates to a photosensitive conductive paste, a method for producing a substrate having a conductive pattern, a method for producing an electronic component, a cured film, a fired body, and an electronic component. [Background technology]

[0002] In recent years, with the demand for smaller size and higher performance in electronic components, there has been a demand for finer internal wiring and higher aspect ratios ((axial thickness of coil conductor layer) / (width of coil conductor layer) in a cross section perpendicular to the extension direction of the coil conductor layer). Inductor components include a ceramic insulator and a coil-shaped internal electrode inside it. The insulator includes multiple insulating layers. The internal electrodes are formed in a planar, winding-like shape on the insulating layers, and the coil is formed by combining these electrodes. It has been proposed to use a photosensitive conductive paste (see, for example, Patent Document 1) as the internal electrode, which allows for finer wiring.

[0003] Methods for manufacturing these inductor components include forming internal electrodes made of photosensitive conductive paste on insulating sheets containing ceramic and resin, and then stacking the resulting sheets to form a coil, and forming a coil by alternately stacking internal electrodes made of photosensitive conductive paste and insulating layers containing ceramic and resin on insulating sheets containing ceramic and resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-215446 Summary of the Invention [Problem to be solved by the invention]

[0005] When applying and drying a photosensitive conductive paste to an insulating sheet to form the internal electrodes, if the paste is dried at a high temperature to completely dry off the solvent, the substrate may warp. To prevent this problem, the solvent must be dried at a low temperature. However, when a conventional photosensitive conductive paste containing only solvents with relatively low boiling points, such as those described in Patent Document 1, is dried at a low temperature, the solvent remains in the dried film. This results in problems such as the amount of remaining solvent changing over time after drying, which can affect processability, and the viscosity of the paste increasing during coating processes such as screen printing, which can change the thickness of the coated film. Furthermore, when only solvents with high boiling points are used, the amount of remaining solvent in the dried film becomes too high, resulting in tackiness.

[0006] In view of the above problems, the present invention aims to suppress an increase in viscosity during the coating process, suppress the tackiness of the dried film even when the photosensitive conductive paste is dried at a low temperature, and suppress changes over time in the amount of residual solvent contained in the dried film. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention mainly has the following configuration: A photosensitive conductive paste containing conductive particles (A), a photosensitive organic component (B), and two or more solvents (C), wherein the difference in boiling point between the solvent (C-1) with the lowest boiling point and the solvent (C-2) with the highest boiling point among the solvents (C) is 35 to 120°C, the boiling point of the solvent (C-2) is 251 to 300°C, and the content of the solvent (C-2) is 25 to 80% by mass relative to 100% by mass of all the solvents. [Effects of the Invention]

[0008] The photosensitive conductive paste of the present invention can suppress an increase in viscosity during the coating process, suppress the tackiness of the dried film even when dried at a low temperature, and suppress changes over time in the amount of residual solvent contained in the dried film. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a schematic diagram showing a mask pattern used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0010] The photosensitive conductive paste of the present invention contains conductive particles (A), a photosensitive organic component (B), and two or more solvents (C), wherein the difference in boiling point between the solvent (C-1) with the lowest boiling point and the solvent (C-2) with the highest boiling point among the solvents (C) is 35 to 120°C, the boiling point of the solvent (C-2) is 251 to 300°C, and the content of the solvent (C-2) is 25 to 80% by mass relative to 100% by mass of all solvents.

[0011] The conductive particles (A) melt and fuse upon heating and firing, becoming a conductive inorganic sintered body. The inclusion of the photosensitive organic component (B) imparts photosensitivity to the dried film of the photosensitive conductive paste, enabling the formation of fine wiring by photolithography. Furthermore, in the present invention, it is important that the photosensitive conductive paste contains two or more solvents (C), and that the difference in boiling point between the solvent (C-1) with the lowest boiling point and the solvent (C-2) with the highest boiling point among the solvents (C) is 35 to 120°C, the boiling point of the solvent (C-2) is 251 to 300°C, and the content of the solvent (C-2) is 25 to 80% by mass relative to 100% by mass of the total solvent. As mentioned above, when the photosensitive conductive paste is dried at low temperatures, there is a problem in that the processability changes due to the change in the amount of remaining solvent. Therefore, the inventors discovered that by using two or more solvents (C) in combination, where the difference in boiling point between the solvent (C-1) with the lowest boiling point and the solvent (C-2) with the highest boiling point is 35 to 120°C, it is possible to dry only the low-boiling solvent while leaving the high-boiling solvent, thereby making it possible to keep the amount of remaining solvent constant.

[0012] (Conductive particles (A)) The conductive particles (A) melt or fuse when heated and sintered, thereby exhibiting electrical conductivity. Examples of the conductive particles (A) include powders of materials selected from metals such as silver, gold, copper, platinum, palladium, tin, nickel, aluminum, tungsten, molybdenum, ruthenium, chromium, titanium, and indium, alloys containing any of these metals, and oxides of any of these metals. Two or more of these may be used. Among these, silver, copper, or gold are preferred as the material for the conductive particles from the viewpoint of electrical conductivity, and silver, copper, or an alloy containing any of these metals is more preferred from the viewpoint of cost, and silver is even more preferred from the viewpoint of stability.

[0013] The average secondary particle diameter (median diameter (D50)) of the conductive particles (A) is preferably 0.3 to 6.0 μm. By making the average secondary particle diameter D50 of the conductive particles (A) 0.3 μm or more, the exposed light can be efficiently transmitted in the exposure and development step described below, allowing curing to proceed sufficiently to the bottom, suppressing pattern peeling and enabling the formation of a thick pattern. The average secondary particle diameter D50 of the conductive particles (A) is more preferably 0.8 μm or more, and even more preferably 1.3 μm or more. On the other hand, by making the average secondary particle diameter D50 of the conductive particles (A) 6.0 μm or less, rattles in the formed pattern can be suppressed and a finer pattern can be formed. The average secondary particle diameter D50 of the conductive particles (A) is more preferably 5.5 μm or less, and even more preferably 5.0 μm or less. The average secondary particle diameter D50 of the conductive particles (A) can be measured by a laser light scattering method using a Microtrac HRA (Model No. 9320-X100; manufactured by Nikkiso Co., Ltd.).

[0014] The content of the conductive particles (A) in the photosensitive conductive paste is preferably 35 to 60% by volume of the total solid content. By making the content of the conductive particles (A) 35% by volume or more, the probability of contact between the conductive particles (A) can be improved in the firing step described below, and breakage of the pattern can be suppressed. The content of the conductive particles (A) is more preferably 40% by volume or more. On the other hand, by making the content of the conductive particles (A) 60% by volume or less, pattern peeling in the exposure and development steps can be suppressed, and a thicker film pattern can be formed. The content of the conductive particles (A) is more preferably 55% by volume or less. Here, the total solid content of the photosensitive conductive paste refers to all components of the photosensitive conductive paste excluding the solvent.

[0015] The content of conductive particles (A) in a photosensitive conductive paste can be determined by observing a vertical cross section of the dried paste film, which is formed by applying and drying the photosensitive paste and thoroughly removing the organic solvent, with a transmission electron microscope (e.g., the JEM-4000EX manufactured by JEOL Ltd.), and then performing image analysis to distinguish between conductive particles (A) and other components based on the image density, thereby calculating the volume fraction of conductive particles (A). The observation area with the transmission electron microscope is approximately 20 μm x 100 μm, and the magnification is approximately 1,000 to 3,000 times. Furthermore, if the amounts of each component of the photosensitive paste are known, the content of conductive particles (A) can also be calculated from the amounts.

[0016] (Photosensitive organic component (B)) The photosensitive organic component (B) refers to an organic component containing an alkali-soluble resin and a photosensitizer. The alkali-soluble resin refers to a resin having an alkali-soluble group. Examples of the alkali-soluble group include a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, and a thiol group. Due to its high solubility in alkaline developers, a carboxyl group is preferred as the alkali-soluble group.

[0017] The alkali-soluble resin is preferably an acrylic resin, and more preferably a copolymer of an acrylic monomer having a carbon-carbon double bond with another monomer. Examples of the acrylic monomer having a carbon-carbon double bond include acrylates having a chain aliphatic hydrocarbon group having 1 to 18 carbon atoms, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, isodecyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, allyl acrylate, lauryl acrylate, and stearyl acrylate; benzyl acrylate, phenyl acrylate, and the like. Examples of suitable copolymerizable components include acrylates having a cyclic aromatic hydrocarbon group having 6 to 10 carbon atoms, such as acrylate, 1-naphthyl acrylate, and 2-naphthyl acrylate; acrylates having a cyclic aliphatic hydrocarbon group having 6 to 15 carbon atoms, such as cyclohexyl acrylate, dicyclopentanyl acrylate, 4-tert-butylcyclohexyl acrylate, dicyclopentenyl acrylate, dicyclopentadienyl acrylate, isobornyl acrylate, and 3,3,5-trimethylcyclohexyl acrylate, as well as acrylates obtained by substituting these acrylates with methacrylates. Two or more of these may be used. Examples of copolymerizable components other than acrylic monomers include styrenes, such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, chloromethylstyrene, and hydroxymethylstyrene; unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, and vinylacetic acid, as well as acid anhydrides thereof. Two or more of these may be used.

[0018] The acrylic resin preferably has a carbon-carbon double bond in the side chain or molecular terminal, which can improve the curing reaction rate during exposure. Examples of structures having a carbon-carbon double bond include a vinyl group, an allyl group, an acrylic group, and a methacrylic group. Two or more of these may be present. Methods for introducing a carbon-carbon double bond into an acrylic resin include, for example, reacting a mercapto group, an amino group, a hydroxyl group, or a carboxyl group in the acrylic resin with a compound having a glycidyl group or an isocyanate group and a carbon-carbon double bond, acrylic acid chloride, methacrylic acid chloride, allyl chloride, or the like.

[0019] Examples of compounds having a glycidyl group and a carbon-carbon double bond include glycidyl methacrylate, glycidyl acrylate, allyl glycidyl ether, glycidyl ethyl acrylate, crotonyl glycidyl ether, glycidyl crotonate, glycidyl isocrotonate, Cyclomer (registered trademark) M100, A200 (all manufactured by Daicel Chemical Industries, Ltd.). Examples of compounds having an isocyanate group and a carbon-carbon double bond include acryloyl isocyanate, methacryloyl isocyanate, acryloylethyl isocyanate, methacryloylethyl isocyanate, etc. Two or more of these may be used.

[0020] Examples of the photosensitizer include a photopolymerization initiator, a dissolution inhibitor, etc. From the viewpoint of forming a thicker conductive pattern, a photopolymerization initiator is preferred.

[0021] Photopolymerization initiators absorb short-wavelength light such as ultraviolet light and decompose, or generate radicals through a hydrogen abstraction reaction, thereby imparting photocurability to the photosensitive conductive paste and enabling pattern formation by negative photolithography. Examples of the photopolymerization initiator that decomposes upon absorbing light such as ultraviolet light include alkylphenone-based photopolymerization initiators such as 1,2-octanedione, benzophenone, methyl ortho-benzoylbenzoate, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4-benzoyl-4'-methyldiphenyl ketone, dibenzyl ketone, 2,2'-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, Michler's ketone, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 4-azidobenzalacetophenone, 2,6-bis(p-azidobenzylidene)cyclohexanone, and 6-bis(p-azidobenzylidene)-4-methylcyclohexanone; acylphosphine oxide-based photopolymerization initiators such as phenyl-phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; and oxime ester-based photopolymerization initiators such as 1-[4-(phenylthio)-2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-2(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, and 1-phenyl-3-ethoxy-propanetrione-2-(O-benzoyl)oxime.

[0022] The dissolution inhibitor increases the solubility of exposed portions of the photosensitive conductive paste dried film in a developer, enabling pattern formation by positive photolithography. Dissolution inhibitors that generate acid upon exposure to light are preferred. Examples of dissolution inhibitors include diazodisulfone compounds, triphenylsulfonium compounds, and quinone diazide compounds. Examples of diazodisulfone compounds include bis(cyclohexylsulfonyl)diazomethane, bis(tert-butylsulfonyl)diazomethane, and bis(4-methylphenylsulfonyl)diazomethane. Examples of triphenylsulfonium compounds include diphenyl-4-methylphenylsulfonium trifluoromethanesulfonate, diphenyl-2,4,6-trimethylphenylsulfonium p-toluenesulfonate, and diphenyl(4-methoxyphenyl)sulfonium trifluoromethanesulfonate. Examples of the quinone diazide compound include a compound in which the sulfonic acid of quinone diazide is bonded to a polyhydroxy compound via an ester bond, a compound in which the sulfonic acid of quinone diazide is bonded to a polyamino compound via a sulfonamide bond, and a compound in which the sulfonic acid of quinone diazide is bonded to a polyhydroxypolyamino compound via an ester bond and / or a sulfonamide bond. Two or more of these compounds may be used.

[0023] The photosensitive organic component (B) may further contain a photosensitive monomer, an ultraviolet absorber, a sensitizer, and the like.

[0024] Photosensitive monomers refer to monomers or oligomers having a carbon-carbon double bond. Examples of structures having a carbon-carbon double bond include acrylic groups, methacrylic groups, vinyl groups, and maleimide rings. Examples of photosensitive monomers having an acrylic group include 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropane tetraacrylate, glycerol diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate, triglycerol diacrylate, trimethylolpropane triacrylate, bisphenol A diacrylate, and isocyanuric acid EO-modified triacrylate. Examples of photosensitive monomers having a methacrylic group include those in which the acrylate is replaced with a methacrylate. Examples of photosensitive monomers having a vinyl group include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, phenyl vinyl ether, ethylene glycol monovinyl ether, and triallyl isocyanurate.

[0025] (Solvent (C)) The solvent (C) is liquid at room temperature and has the effect of wetting or dissolving the components constituting the photosensitive conductive paste, making it a liquid with excellent coatability. As described above, the photosensitive conductive paste of the present invention contains two or more types of solvent (C), and it is important that the difference in boiling point between the solvent (C-1) with the lowest boiling point and the solvent (C-2) with the highest boiling point among the solvents (C) is 35 to 120°C, and that the boiling point of solvent (C-2) is 251 to 300°C.

[0026] If the boiling point of the solvent (C-2) is lower than 251°C, the solvent (C-2) will volatilize during the drying process described below, resulting in a significant change in the amount of remaining solvent over time. On the other hand, if the boiling point of the solvent (C-2) is higher than 300°C, the binder removal properties during firing will decrease. The boiling point of the solvent (C-2) is preferably 257°C or higher in order to further prevent the amount of remaining solvent from changing over time. Furthermore, it is preferably 290°C or lower in order to further prevent the binder removal properties during firing from decreasing. Here, the boiling point of the organic solvent (C) is disclosed in various documents and is rounded to one decimal place. If not disclosed in the documents, it can be measured according to the method of JIS standard K0066-1992.

[0027] Furthermore, if the boiling point difference between solvent (C-1) and solvent (C-2) is less than 35°C, it becomes difficult to selectively dry only solvent (C-1) and suppress tackiness of the dried film. On the other hand, if the boiling point difference is more than 120°C, the boiling point of solvent (C-1) becomes too low, and in the coating step described below, the viscosity of the photosensitive conductive paste is likely to increase due to solvent evaporation. From the viewpoint of further suppressing tackiness, the boiling point difference between solvent (C-1) and solvent (C-2) is preferably 40°C or more, and more preferably 50°C or more. From the viewpoint of further preventing the boiling point of solvent (C-1) from becoming too low, the boiling point difference is preferably 110°C or less, and more preferably 100°C or less.

[0028] The solvent (C-1) preferably has a boiling point of 180 to 230°C. By setting the boiling point of the solvent (C-1) to 180°C or higher, it is possible to further suppress an increase in viscosity of the photosensitive conductive paste during the coating step. On the other hand, by setting the boiling point of the solvent (C-1) to 230°C or lower, it is possible to easily dry the photosensitive conductive paste during the drying step described below. From the above viewpoints, the boiling point of the solvent (C-1) is more preferably 185°C or higher, and more preferably 220°C or lower. The boiling point of the solvent refers to the boiling point at 1013.25 hPa.

[0029] Examples of the solvent (C-1) include ethylene glycol hexyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol n-butyl ether, diethylene glycol ethyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, diethylene glycol methyl ether, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, dipropylene glycol n-butyl ether, dipropylene glycol propyl ether, dipropylene glycol methyl-n-propyl ether, dipropylene glycol methyl ether, dipropylene glycol methyl ether acetate, dipropylene glycol monomethyl ether acetate, dimethylimidazolidinone, dimethyl sulfoxide, triethylene glycol dimethyl ether, and propylene glycol diacetate.

[0030] Examples of the solvent (C-2) include 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, diethylene glycol hexyl ether, diethylene glycol mono-2-ethylhexyl ether, diethylene glycol monohexyl ether, dipropylene glycol phenyl ether, tetraethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, triethylene glycol monobutyl ether, tripropylene glycol butyl ether, tripropylene glycol monobutyl ether, and diethylene glycol dibutyl ether. Among these, those with an SP value of 14.6 to 21.5 (J / cm 3 ) 1 / 2 The SP value is preferably 14.6 to 21.5 (J / cm 3 ) 1 / 2Examples of the compounds include 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, tetraethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, and diethylene glycol dibutyl ether. By setting the SP value to 14.6 or more, the photosensitive organic component (B) can be wetted or dissolved. By setting the SP value to 21.5 or less, when processed onto an insulating resin layer containing a ceramic, as described below, penetration into the insulating layer can be prevented and residue on the insulating layer can be suppressed. An SP value of 20.5 or less is more preferable as it can more effectively exhibit the above effects. The SP value can be calculated from the molecular structure using the Fedors calculation method.

[0031] Solvent (C-2) is R 1 (OC2H4) n OR 2 or R 1 (OC3H6) n OR 2 where n is an integer of 2 to 5, and R 1 is H or an alkyl group having 1 to 6 carbon atoms, R 2 represents an alkyl group having 1 to 6 carbon atoms. Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, and an n-butyl group. When the solvent (C-2) is the glycol alkyl ether, penetration into the insulating layer can be more effectively prevented, and residues can be reduced.

[0032] Furthermore, it is important that the content of solvent (C-2) in the photosensitive conductive paste of the present invention is 25 to 80% by mass relative to 100% by mass of all solvents. If the content of solvent (C-2) is less than 25% by mass, the viscosity of the photosensitive conductive paste is likely to increase due to evaporation of the solvent in the coating step described below. The content of solvent (C-2) is preferably 35% by mass or more. On the other hand, if the content of solvent (C-2) is more than 80% by mass, tackiness of the dried film is likely to occur. The content of solvent (C-2) is preferably 70% by mass or less, more preferably 60% by mass or less. The content of solvent (C-2) is determined based on the total types of solvents contained in the photosensitive conductive paste. 1After identification by chemical analysis such as H-NMR, the ratio can be calculated by determining the peak area in a gas chromatogram.

[0033] (shrinkage inhibitor) (Non-conductive inorganic particles) The photosensitive conductive paste of the present invention preferably further contains a non-conductive inorganic powder, which can suppress pattern shrinkage during firing. The particle diameter of the non-conductive inorganic powder is preferably 1 to 100 nm. Examples of non-conductive inorganic powders include alumina (Al2O3), zirconia (ZrO2), magnesia (MgO), beryllia (BeO), mullite (3Al2O3·2SiO2), cordierite (5SiO2·2Al2O3·2MgO), spinel (MgO·Al2O3), forsterite (2MgO·SiO2), anorthite (CaO·Al2O3·2SiO2), celsian (BaO·Al2O3·2SiO2), silica (SiO2), aluminum nitride (AlN), ferrite (garnet type: Y3Fe5O 12 Examples of suitable fillers include glass powders containing, for example, SiO2, Al2O3, CaO, BO3, MgO, and / or TiO2; and inorganic filler powders such as alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, anorthite, celsian, silica, and aluminum nitride. Two or more of these may be used. Among these, silica particles are preferred for their ability to further suppress firing defects. The silica particles are preferably surface-alkylated, particularly dialkylsilylated and / or trialkylsilylated, for reducing the thixotropy of the photosensitive conductive paste and improving the surface smoothness of the coating film. Examples of methods for dialkylsilylating and / or trialkylsilylating the surfaces of silica particles include reacting the silica particles with dimethyldichlorosilane or hexamethyldisilazane.

[0034] (Other ingredients) The photosensitive conductive paste of the present invention may contain dispersants, plasticizers, leveling agents, surfactants, silane coupling agents, antifoaming agents, stabilizers, etc., within limits that do not impair the desired properties.

[0035] (dispersant) The dispersant is a component that has the effect of dispersing and stabilizing the conductive particles (A) and / or non-conductive inorganic particles. Examples of dispersants include amine-based dispersants and carboxylic acid or carboxylic acid ester-based dispersants. Among these, unsaturated fatty acids having 3 to 18 carbon atoms and / or saturated fatty acids having 3 to 18 carbon atoms are preferred because they suppress the generation of residue and facilitate the formation of a thick film. Examples of unsaturated fatty acids include myristoleic acid, palmitoleic acid, sapienic acid, and oleic acid. Examples of saturated fatty acids include capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, and stearic acid.

[0036] (Method for manufacturing photosensitive conductive paste) The photosensitive conductive paste of the present invention can be obtained, for example, by mixing and / or dispersing the aforementioned components (A) to (C) and, if necessary, other additives. Examples of devices for mixing and / or dispersing include dispersers such as triple rollers and ball mills, and kneaders.

[0037] (cured film) Next, the cured film of the present invention will be described. The cured film of the present invention is a film obtained by curing the photosensitive conductive paste of the present invention. The film thickness of the cured film is preferably 5 to 30 μm. By making the film thickness of the cured film 5 μm or more, it is possible to suppress wire breakage during firing. On the other hand, by making the film thickness of the cured film 30 μm or less, it is possible to form fine wiring.

[0038] The cured film of the present invention may have a predetermined pattern shape. Examples of the pattern shape include a linear shape and a spiral shape. The minimum width of the pattern shape is preferably 10 to 50 μm. By setting the pattern width to 10 μm or more, it is possible to suppress wire breakage during firing. On the other hand, by setting the pattern width to 50 μm or less, the aspect ratio of the pattern becomes large, and the sheet resistance of the internal wiring can be reduced.

[0039] The cured film of the present invention can be obtained, for example, by applying the photosensitive conductive paste of the present invention to a substrate, drying it, and photocuring it by exposure. A cured film having a pattern shape can be produced by pattern exposure in an exposure step and then developing it.

[0040] (Method of manufacturing a substrate having a conductive pattern) The method for producing a substrate having a conductive pattern of the present invention includes the steps of applying the photosensitive conductive paste of the present invention onto a substrate to form a coating film, drying the coating film to form a dry film, and exposing and developing the dry film to form a pattern, wherein the amount of solvent remaining in the dry film in the pattern-forming step is 25 to 80 mass % of the total amount of solvent contained in the photosensitive conductive paste. Each step is described in detail below.

[0041] First, the photosensitive conductive paste of the present invention is applied onto a substrate to form a coating film.

[0042] Examples of the coating method in the coating step include spray coating, roll coating, screen printing, and coating methods using a blade coater, a die coater, a calendar coater, a meniscus coater, a bar coater, etc. The thickness of the coating film can be appropriately selected depending on the coating method, the solids concentration and viscosity of the photosensitive paste, etc.

[0043] The coating film using the photosensitive conductive paste of the present invention described above may be formed on a film containing inorganic particles (D) and an organic component (E) formed on a substrate, and then the coating film may be formed on the film.

[0044] A slurry in which inorganic particles are dispersed in a solution containing an organic component (E) and a solvent is applied to a substrate and dried to form a film. The organic component (E) refers to all organic components remaining after the film is formed. Examples of slurries in which inorganic components are dispersed include non-photosensitive slurries and photosensitive slurries. The non-photosensitive slurry contains inorganic particles, a resin, a solvent, etc. The photosensitive slurry contains inorganic particles, a photosensitive organic component, a solvent, etc. The photosensitive organic component refers to a mixture of an alkali-soluble resin, a photosensitizer, a photosensitive monomer, etc. A photosensitive slurry is preferred from the viewpoint of being able to form fine vias with good positional accuracy when a film containing inorganic particles (D) and the organic component (E) is formed. In other words, the organic component (E) preferably contains a photosensitive organic component. The organic component (E) may further contain a dispersant, a plasticizer, a leveling agent, etc., as appropriate.

[0045] Examples of the inorganic particles (D) include glass particles that soften in the firing temperature range, inorganic particles that do not soften in the firing temperature range and exist as particles, etc. These can also be used in combination.

[0046] Examples of glass particles that soften in the firing temperature range include glass particles containing SiO2, B2O3, K2O, Li2O, CaO, ZnO, Bi2O3, and Al2O3.

[0047] Examples of inorganic particles that do not soften and exist as particles in the firing temperature range include SiO2-B2O3-based glass, quartz, alumina, magnesia, spinel, silica, forsteride, steatite, zirconia, etc. Two or more of these may be used in combination.

[0048] Next, the coated film is dried to form a dry film.

[0049] In the method for producing a substrate having a conductive pattern of the present invention, the amount of solvent remaining in the dried film is 25 to 80 mass % of the total amount of solvent contained in the photosensitive conductive paste. By setting the amount of remaining solvent to 25 mass %, the light transmittance of the dried film is improved, and a pattern with a high aspect ratio can be formed. On the other hand, by setting the amount of remaining solvent to 80 mass % or less, the tackiness of the dried film can be suppressed.

[0050] Drying methods include, for example, heat drying using a heating device such as an oven, a hot plate, or infrared, and vacuum drying. The drying temperature is preferably 45 to 80°C. By setting the drying temperature to 45°C or higher, the low boiling point solvent (C-1) can be efficiently volatilized and removed, and tackiness of the dried film can be suppressed. On the other hand, by setting the drying temperature to 80°C or lower, evaporation of the high boiling point solvent (C-2) can be suppressed, and warping of the substrate can be suppressed. The heating time is preferably 2 to 60 minutes.

[0051] Next, the dried film is exposed to light and developed to form a pattern.

[0052] Exposure methods include exposure through a photomask and exposure without using a photomask. Examples of exposure methods without using a photomask include direct writing using laser light, etc. Examples of exposure devices include stepper exposure machines and proximity exposure machines. Examples of actinic rays used for exposure include near-ultraviolet rays, ultraviolet rays, electron beams, X-rays, laser light, etc., with ultraviolet rays being preferred. Examples of ultraviolet light sources include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, halogen lamps, and germicidal lamps, with ultra-high-pressure mercury lamps being preferred.

[0053] Examples of developers for alkaline development include aqueous solutions of tetramethylammonium hydroxide, diethanolamine, diethylaminoethanol, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, diethylamine, methylamine, dimethylamine, dimethylaminoethyl acetate, dimethylaminoethanol, dimethylaminoethyl methacrylate, cyclohexylamine, ethylenediamine, hexamethylenediamine, etc. To these aqueous solutions, polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, γ-butyrolactone, etc.; alcohols such as methanol, ethanol, isopropanol, etc.; esters such as ethyl lactate, propylene glycol monomethyl ether acetate, etc.; cyclopentanone, cyclohexanone, isobutyl ketone, ketones such as methyl isobutyl ketone, etc.; surfactants, etc. may be added.

[0054] Examples of the developing method include a method in which a developer is sprayed onto a substrate on which a cured film has been formed after exposure while the substrate is left standing, transported, or rotated; a method in which a substrate on which a cured film has been formed after exposure is immersed in a developer; and a method in which ultrasonic waves are applied to a substrate on which a cured film has been formed after exposure while the substrate is immersed in a developer.

[0055] The pattern obtained by development may be subjected to a rinse treatment using a rinse solution. Examples of rinse solutions include water; aqueous solutions of alcohols such as ethanol and isopropyl alcohol; and aqueous solutions of esters such as ethyl lactate and propylene glycol monomethyl ether acetate. Furthermore, a step of drying the remaining solvent in the pattern may be included. By drying the remaining solvent, the shrinkage rate can be reduced when baking is performed. The drying method may use the same drying device as in the drying method described above.

[0056] The obtained patterns can also be laminated to form a laminate. The number of layers in the laminate is preferably 2 to 30. By making the number of layers 2 or more, the thickness of the predetermined pattern can be increased. On the other hand, by making the number of layers 30 or less, the influence of misalignment between layers can be reduced.

[0057] (fired body) Next, the sintered body of the present invention will be described. The sintered body of the present invention is obtained by sintering the cured film of the present invention, and its shape is not important. Preferred conditions for the sintering step will be described later.

[0058] The thickness of the fired body is preferably 2 to 20 μm. By making the thickness of the fired body 2 μm or more, disconnection during firing can be suppressed. On the other hand, by making the thickness of the fired body 20 μm or less, swelling during firing can be suppressed.

[0059] The line width of the fired body of the present invention is preferably 5 to 40 μm. By making the line width of the fired body 5 μm or more, it is possible to suppress disconnection during firing. On the other hand, by making the line width of the fired body 40 μm or less, it is possible to form a conductive pattern with a high aspect ratio.

[0060] (electronic parts) The electronic component of the present invention includes the sintered body of the present invention, and examples of the electronic component include a chip inductor and an LC filter.

[0061] (Electronic component manufacturing method) The method for producing an electronic component of the present invention includes a firing step of firing the substrate with a conductive pattern obtained by the method for producing a substrate with a conductive pattern of the present invention. The method also preferably includes a step of applying a photosensitive conductive paste, a drying step, and a step of exposing and developing. As an example of the method for producing an electronic component of the present invention, a method for producing a multilayer chip inductor will be described below.

[0062] First, via holes are formed in a ceramic green sheet, and a conductor is embedded in the via holes to form interlayer connection wiring. Examples of methods for forming via holes include laser irradiation. Examples of methods for embedding a conductor in a via hole include embedding a conductor paste by screen printing and drying. Examples of conductor pastes include pastes containing copper, silver, or a silver-palladium alloy. Because the interlayer connection wiring and internal wiring can be formed simultaneously, simplifying the process, the photosensitive conductive paste of the present invention is preferred as the conductor paste.

[0063] Internal wiring is formed on the ceramic green sheet on which the interlayer connection wiring has been formed. Examples of methods for forming the internal wiring include photolithography using a photosensitive conductive paste. The photosensitive paste of the present invention described above is preferably used as the photosensitive conductive paste, as it provides a high aspect ratio and excellent conductivity. If necessary, a dielectric pattern or an insulator pattern is further formed on the ceramic green sheet. Examples of methods for forming the dielectric pattern and the insulator pattern include screen printing.

[0064] Next, a plurality of ceramic green sheets on which interlayer connection wiring and internal wiring have been formed are laminated and thermocompression bonded to obtain a laminate. Examples of lamination methods include stacking ceramic green sheets using guide holes. Examples of thermocompression bonding devices include hydraulic presses. The thermocompression bonding temperature is preferably 90 to 130°C, and the thermocompression bonding pressure is preferably 5 to 20 MPa.

[0065] The resulting laminate is diced into desired chip sizes using a cutting device, fired, coated with terminal electrodes, and plated to obtain a multilayer chip inductor. Examples of cutting devices include a die cutter and a laser cutter. Examples of firing methods include heat treatment at 300 to 600°C for 5 minutes to several hours, followed by further heat treatment at 850 to 900°C for 5 minutes to several hours. Examples of methods for applying terminal electrodes include sputtering. Examples of metals used in plating include nickel and tin. [Example]

[0066] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these. It should be noted that Examples 4-6 and 22 are currently reference examples, and Examples 1-3, 7-21, 23 and 24 are examples of the present invention.

[0067] (Photosensitive conductive paste) The raw materials used for the photosensitive conductive paste are as follows:

[0068] Conductive particles (A) Conductive particles (A-1): Ag particles with a D50 of 3.2 μm Conductive particles (A-2): Ag particles with a D50 of 0.5 μm Conductive particles (A-3): Ag particles with a D50 of 1.1 μm Conductive particles (A-4): Ag particles with a D50 of 2.0 μm Conductive particles (A-5): Ag particles with a D50 of 4.0 μm Conductive particles (A-6): Ag particles with D50 of 5.3 μm The D50 of the conductive particles was measured by a laser light scattering method using a particle size distribution measuring device (Microtrac HRA Model No. 9320-X100; manufactured by Nikkiso Co., Ltd.).

[0069] Photosensitive organic component (B) Alkali-soluble resin: Acrylic resin (weight average molecular weight 30,000, glass transition point 110°C, acid value 100mgKOH / g) obtained by addition reaction of 40 mole parts of glycidyl methacrylate with 100 mole parts of carboxyl groups in a copolymer of methacrylic acid / methyl methacrylate / styrene = 54 / 23 / 23 (molar ratio).

[0070] Photosensitive monomer: NK Oligo UA-122P (urethane acrylate containing an ester structure, viscosity 7.0 Pa·s, weight-average molecular weight 1,100, manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0071] Photosensitizer (photopolymerization initiator 1): Adeka Optomer N-1919 (manufactured by ADEKA Corporation).

[0072] (Other ingredients) Leveling agent: "Disparlon" (registered trademark) L-1980N (manufactured by Kusumoto Chemicals Co., Ltd.).

[0073] Dispersant 1: Stearic acid Dispersant 2: Oleic acid Dispersant 3: FLORENE G-700 (manufactured by Kyoeisha Chemical Co., Ltd.).

[0074] (Solvent (C)) Solvent 1: Ethylene glycol butyl ether (boiling point: 168°C, SP value: 22.1 (J / cm 3 ) 1 / 2 ) Solvent 2: Ethylene glycol monobutyl ether acetate (boiling point: 188°C, SP value: 18.9 (J / cm 3 ) 1 / 2 ) Solvent 3: Dipropylene glycol monobutyl ether (boiling point: 230°C, SP value: 20.9 (J / cm 3 ) 1 / 2 ) Solvent 4: Diethylene glycol dibutyl ether (boiling point: 256°C, SP value: 17.0 (J / cm 3 ) 1 / 2 ) Solvent 5: Tetraethylene glycol dimethyl ether (boiling point: 275°C, SP value: 17.5 (J / cm3 ) 1 / 2 ) Solvent 6: Triethylene glycol butyl methyl ether (boiling point: 261°C, SP value: 17.2 (J / cm 3 ) 1 / 2 ) Solvent 7: 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (boiling point: 280°C, SP value: 18.5 (J / cm 3 ) 1 / 2 ) Solvent 8: Triethylene glycol monobutyl ether (boiling point: 271°C, SP value: 21.1 (J / cm 3 ) 1 / 2 ) Solvent 9: Dipropylene glycol phenyl ether (boiling point: 280°C, SP value: 23.0 (J / cm 3 ) 1 / 2 ) Solvent 10: Diethylene glycol butyl ether (boiling point: 150°C, SP value: 21.5 (J / cm 3 ) 1 / 2 ) The SP value of the solvent (C) was calculated from the molecular structure using the Fedors calculation method.

[0075] Non-conductive inorganic particles D-1: "AEROSIL" (registered trademark) 300 (manufactured by Nippon Aerosil Co., Ltd.): silica particles D-2: "AEROSIL" (registered trademark) R976 (manufactured by Nippon Aerosil Co., Ltd.): silica particles whose particle surfaces are dialkylsilylated.

[0076] Example 1 5.0 g of alkali-soluble resin, 2.4 g of NK Oligo UA-122P (photosensitive monomer), 0.5 g of Adeka Optomer N-1919 (photopolymerization initiator 1), 0.1 g of Disparlon (registered trademark) L-1980N (leveling agent), 0.1 g of Dispersant 1, 5.9 g of ethylene glycol monobutyl ether acetate (solvent 2), and 5.9 g of diethylene glycol dibutyl ether (solvent 4) were mixed to obtain 19.9 g of a photosensitive resin solution.

[0077] 19.9 g of the resulting photosensitive resin solution and 61.6 g of Ag particles (A-1) were mixed and kneaded using three rollers to obtain the photosensitive conductive paste P-1 shown in Table 1.2. The content (volume %) of the conductive particles (A) in the total solid content was calculated from the weight and density of each component. However, the density of all organic components was 1.0 g / cm. 3 It was calculated as:

[0078] <Evaluation of viscosity change rate> The viscosity change rate of the photosensitive conductive paste was measured as follows. 300 g of photosensitive conductive paste was placed on a screen stencil and applied to an alumina substrate in a 100 mm square pattern so that the paste weight was 0.6 g. This printing process was repeated 300 times, and the viscosity change of the paste on the screen stencil before and after 300 printings was evaluated. A viscosity change rate of 0% to less than 5% from before printing was rated "excellent," 5% to less than 10% was rated "good," 10% to less than 20% was rated "passable," and 20% or more was rated "unacceptable." The viscosity was measured at 10 rpm using a Brookfield viscometer, and the viscosity change rate was calculated using the following formula:

[0079] Viscosity change rate (%) = (viscosity after printing / viscosity before printing-1) x 100.

[0080] <Paste solvent ratio and aging change rate evaluation> 1.00 g of the photosensitive conductive paste was placed in an aluminum cup and dried at 150°C for 2 hours, after which the weight of the photosensitive conductive paste was measured. From the change in the mass of the paste before and after heating, the ratio (mass%) of the solvent contained in the photosensitive conductive paste (hereinafter referred to as the paste solvent ratio) was calculated using the following formula. Paste solvent ratio (mass%) = (1.00 g - paste weight after drying) / 1.00 g × 100.

[0081] Next, the photosensitive conductive paste was applied to an alumina substrate by screen printing in a 100 mm square pattern so that the film thickness after drying would be 15 μm, and the weight of the applied paste (b) was measured. Next, the substrate with the paste applied was dried at 60°C for 10 minutes, and the weight of the dried film (c) was measured within 10 minutes after drying. The residual solvent ratio (initial) was calculated using the following formula. Residual solvent amount·initial (mass%) = (paste solvent ratio−(1−(weight of dried film (c) / weight of applied paste (b))) × 100) / paste solvent ratio × 100.

[0082] Furthermore, after drying, the weight of the dried film after 10 hours at room temperature was measured in the same manner as above, and the amount of remaining solvent after 10 hours was calculated. The rate of change over time of the amount of solvent remaining in the dried film (hereinafter referred to as the rate of change over time) was calculated using the following formula. Change rate over time (%) = (1 - (remaining solvent amount after 10 hours) / (remaining solvent amount initial)) × 100.

[0083] A change rate over time of 0% or more but less than 5% was rated "excellent," 5% or more but less than 10% was rated "good," 10% or more but less than 20% was rated "passable," and 20% or more was rated "unacceptable."

[0084] <Tackiness evaluation> A photosensitive conductive paste was screen-printed onto an alumina substrate in a 100mm square pattern to a thickness of 15μm after drying, and then dried at 60°C for 10 minutes to produce a dried film. A PET film and a 50g weight with a 50mm square area were placed on the dried film for 1 minute, and the tackiness of the dried film was evaluated based on the area of ​​the dried film transferred to the PET film. A transfer area of ​​0% to less than 1% of the 50mm square was rated "excellent," 1% to less than 5% was rated "good," 5% to less than 10% was rated "fair," and 10% or more was rated "unacceptable."

[0085] <Flatness evaluation> Dry films were prepared using the same method as in <Tack Evaluation>. Using a laser microscope VK-X200 (Keyence Corporation) with an objective lens of 20x magnification, the surface roughness Sa of the dry film was measured. Surface roughness Sa (arithmetic mean height) of less than 0.3 μm was rated "excellent," 0.3 μm or more but less than 0.5 μm was rated "good," 0.5 μm or more but less than 0.7 μm was rated "fair," and 0.7 μm or more was rated "poor."

[0086] <Processability evaluation (maximum film thickness)> A photosensitive conductive paste was applied to an alumina substrate, and the thickness of the dried film was varied in 1-μm increments to achieve a film thickness of 10–20 μm. A stripe-patterned exposure mask with an L (line opening width) / S (space width) ratio of 25 / 35 was used to perform full-line exposure using an exposure system (PEM-6M; manufactured by Union Optical Co., Ltd.) at an exposure dose that resulted in a line width of 30 μm. The substrate was then immersed in a 0.2% by mass Na2CO3 solution, rinsed with ultrapure water, and developed to remove the unexposed portions of the dried film. The maximum film thickness without breakage or peeling after development was determined. The line width of the conductive pattern was measured by observation at 1000x magnification using an optical microscope. The film thickness of the conductive pattern was measured using a stylus-type step profiler (e.g., "Surfcom" (registered trademark) 1400; manufactured by Tokyo Seimitsu Co., Ltd.).

[0087] <Sheet resistance evaluation> A conductive pattern was formed on an alumina substrate with the maximum film thickness using the same method as in <Processability Evaluation (Maximum Film Thickness)>. However, the exposure mask used was the mask pattern shown in Figure 1, with an opening width of 25 μm and a length of 40 mm. The resulting substrate with conductive pattern was fired at 880°C for 10 minutes to obtain a fired conductive pattern. The resistance value R of the fired conductive pattern was measured using a digital multimeter (CDM-16D; manufactured by Custom). Next, the post-fired line width and post-fired film thickness of the fired conductive pattern were measured using the same method as above, and the aspect ratio and sheet resistance were calculated using the following equations. Aspect ratio = film thickness after firing (μm) / line width after firing (μm) Sheet resistance (mΩ / □) = conductive pattern resistance value (mΩ) × line width (mm) ÷ conductive pattern length (mm).

[0088] <Residue evaluation> A substrate with an insulating ceramic layer was produced by the following procedure.

[0089] A substrate with an insulating ceramic layer was prepared by mixing 100 parts by volume of "Parceram" (registered trademark) BT149 (manufactured by Nippon Chemical Industry Co., Ltd.) as insulating ceramic powder, 240 parts by volume of polyvinyl butyral resin as binder resin, 80 parts by volume of dibutyl phthalate as plasticizer, and 160 parts by volume of ethylene glycol monobutyl ether as solvent, applying the mixture to a PET film by the doctor blade method, and drying at 70°C for 10 minutes.

[0090] A dry film was formed on the substrate with the insulating ceramic layer using the same method as in <Tack Evaluation>. The substrate was then immersed in a 0.2% by mass Na2CO3 solution and rinsed with ultrapure water to dissolve the dry film. The amount of residue of the dry film remaining on the substrate after rinsing was evaluated. Evaluation was performed using a scanning electron microscope (S2400; manufactured by Hitachi, Ltd.) at 500x magnification, and the number of conductive particles remaining within a 250 μm × 250 μm area was counted. Ten locations were evaluated, and an average of 0 to 5 particles was rated as "excellent," 6 to 10 particles as "good," 11 to 20 particles as "good," 21 to 30 particles as "fair," and 31 or more particles as "poor."

[0091] (Examples 2 to 22, Comparative Examples 1 to 5) Photosensitive resin solutions were prepared in the same manner as in Example 1, except that the solvents were changed as shown in Tables 2 and 4. The mass ratio of the amount of each solvent to the total amount of solvent was as shown in Tables 2 and 4. Next, the photosensitive resin solutions and the conductive particles shown in Tables 1 and 3 were mixed in the same manner as in Example 1 to prepare photosensitive conductive pastes P-2 to 22 and R-1 to 5. However, the ratio of the photosensitive resin solution to the conductive particles was adjusted so that the volume ratio of the conductive particles in the total solid content was as shown in Tables 1 and 3. The density of the photosensitive resin solutions was 1.0 g / cm 3The photosensitive conductive pastes P-2 to 22 and R-1 to 5 thus prepared were then evaluated in the same manner as in Example 1. The results are shown in Tables 5 and 6.

[0092] (Examples 23 and 24) A photosensitive resin solution was prepared in the same manner as in Example 1. Next, the photosensitive resin solution, conductive particles, and non-conductive inorganic particles were mixed together in the volume ratios shown in Table 3 and kneaded using a triple roller to prepare photosensitive conductive pastes P-23 and 24 shown in Tables 3 and 4. However, the density of the photosensitive resin solution was 1.0 g / cm. 3 , the density of the non-conductive inorganic particles is 2.2 g / cm 3 The photosensitive conductive pastes P-23 and P-24 thus prepared were then evaluated in the same manner as in Example 1. The results are shown in Table 6.

[0093] [Table 1]

[0094] [Table 2]

[0095] [Table 3]

[0096] [Table 4]

[0097] [Table 5]

[0098] [Table 6] [Industrial Applicability]

[0099] The photosensitive conductive paste of the present invention can be suitably used for producing internal wiring patterns for electronic components and the like. [Explanation of symbols]

[0100] 1 Mask Pattern L Mask opening width

Claims

1. The ink contains conductive particles (A), a photosensitive organic component (B), and two or more solvents (C), Among the solvents (C), the difference in boiling point between the solvent (C-1) having the lowest boiling point and the solvent (C-2) having the highest boiling point is 35 to 120°C; The boiling point of the solvent (C-1) is 180 to 230°C, The boiling point of the solvent (C-2) is 251 to 300°C, the SP value of the solvent (C-2) is 14.6 to 20.5 (J / cm 3 ) 1 / 2 , The solvent (C-2) is a glycol alkyl ether represented by R 1 (OC 2 H 4 ) n OR 2 or R 1 (OC 3 H 6 ) n OR 2 : where n is an integer of 2 to 5, R 1 is hydrogen or an alkyl group having 1 to 6 carbon atoms, and R 2 is an alkyl group having 1 to 6 carbon atoms. A photosensitive conductive paste in which the content of the solvent (C-2) is 25 to 80 mass % relative to 100 mass % of the total solvent.

2. 2. The photosensitive conductive paste according to claim 1, further comprising silica particles, the surfaces of which are dialkylsilylated and / or trialkylsilylated.

3. 2. The photosensitive conductive paste according to claim 1, wherein the conductive particles (A) are silver, copper, or an alloy containing any of these metals, and have an average secondary particle diameter (median diameter (D50)) of 0.3 to 6.0 μm.

4. 2. The photosensitive conductive paste according to claim 1, further comprising an unsaturated fatty acid having 3 to 18 carbon atoms and / or a saturated fatty acid having 3 to 18 carbon atoms.

5. 10. A method for producing a substrate with a conductive pattern, comprising the steps of: applying the photosensitive conductive paste according to claim 1 onto a substrate to form a coating film; drying the coating film to form a dry film; and exposing and developing the dry film to form a pattern, wherein the amount of solvent remaining in the dry film is 25 to 80 mass % of the total amount of solvent contained in the photosensitive conductive paste.

6. A method for producing a substrate with a conductive pattern, comprising the steps of: forming a film containing inorganic particles (D) and an organic component (E) on a substrate; applying the photosensitive conductive paste according to claim 1 on the film to form a coating film; drying the coating film at 45 to 80°C to form a dry film; and exposing and developing the dry film to form a pattern, wherein the amount of solvent remaining in the dry film is 25 to 80% by mass of the total amount of solvent contained in the photosensitive conductive paste.

7. The method for producing a substrate having a conductive pattern according to claim 6, wherein the organic component (E) contains a photosensitive organic component.

8. A method for producing an electronic component, comprising a firing step of firing a substrate having a conductive pattern obtained by the method for producing a substrate having a conductive pattern according to any one of claims 5 to 7.

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