Photosensitive conductive paste, cured product, method for manufacturing insulating ceramic layer with circuit pattern, method for manufacturing electronic component, method for manufacturing substrate with circuit pattern, and method for manufacturing inductor

Abstract

The purpose of the present invention is to provide a photosensitive conductive paste which makes it possible to form a high-resolution circuit pattern and exhibits low shrinkage when sintering the circuit pattern.　The present invention is a photosensitive conductive paste which contains a conductive powder (A) and a photosensitive organic component (B), wherein the median size r of the particle diameter distribution of the conductive powder (A) is 3.0-6.0μm, inclusive, and the content V1 of the conductive powder (A) constitutes 37-55 vol%, inclusive, of the solid content overall.

Description

[Technical Field]

[0001] The present invention relates to a photosensitive conductive paste, a cured product, a fired product, an electronic component, a method for producing an insulating ceramic layer having a circuit pattern, and a method for producing an electronic component. [Background technology]

[0002] In recent years, as electronic components have become faster, higher frequency, and smaller, there has been a demand for forming fine, low-resistance circuit patterns on the substrates on which they are mounted. For example, a photosensitive conductive paste has been proposed (see, for example, Patent Document 1) that can form high-definition circuit patterns on green sheets and suppress firing defects. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 202889 Summary of the Invention [Problem to be solved by the invention]

[0004] One example of a method for producing electronic components is to form a circuit pattern on an insulating ceramic layer using a photosensitive conductive paste, and then stack and fire the resulting insulating ceramic layer with the circuit pattern. However, when the photosensitive conductive paste described in Patent Document 1 is used, there is a problem that when fired, the area where many circuit patterns are stacked shrinks significantly, which is significantly different from the shrinkage of the insulating ceramic layer, and this can easily cause bending at the edge of the electronic component, chipping, or peeling between layers.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a photosensitive conductive paste that allows the formation of a high-definition circuit pattern and that causes only a small amount of shrinkage when the circuit pattern is fired. [Means for solving the problem]

[0006] That is, the present invention is a photosensitive conductive paste containing conductive particles (A) and a photosensitive organic component (B), wherein the median diameter r of the particle size distribution of the conductive particles (A) is 3.0 μm or more and 6.0 μm or less, and the content V1 of the conductive particles (A) in the total solid content is 37 vol% or more and 55 vol% or less.

[0007] The present invention also relates to a cured product obtained by curing the photosensitive conductive paste of the present invention.

[0008] The present invention also relates to a fired body obtained by firing the photosensitive conductive paste of the present invention.

[0009] The present invention also relates to an electronic component comprising the sintered body of the present invention and an insulating ceramic layer.

[0010] The present invention also provides a method for producing an insulating ceramic layer having a circuit pattern, comprising the steps of applying the photosensitive conductive paste of the present invention onto an insulating ceramic layer to obtain a coating film, drying the coating film to obtain a dry film, and exposing and developing the dry film to obtain a circuit pattern.

[0011] The present invention also provides a method for producing an electronic component, comprising the steps of: obtaining a laminate by repeating the following steps A to F in this order multiple times on an insulating ceramic layer having a circuit pattern obtained by the method for producing an insulating ceramic layer having a circuit pattern of the present invention; and firing the laminate. Step A: A step of applying a photosensitive insulating ceramic composition to obtain a coating film Step B: A step of drying the coating film to obtain a dry film. Step C: A step of exposing and developing the dried film to obtain an insulating ceramic layer. Step D: A step of applying the photosensitive conductive paste according to any one of claims 1 to 4 onto the insulating ceramic layer to obtain a coating film. Step E: A step of drying the coating film to obtain a dry film. Step F: A step of exposing and developing the dried film to obtain a circuit pattern.

[0012] The present invention also provides a photosensitive insulating ceramic composition, comprising: a step of exposing the coating film of the photosensitive insulating ceramic composition to light in a desired pattern; a step of developing the exposed coating film of the photosensitive insulating ceramic composition to form an insulating layer having grooves; applying the photosensitive conductive paste of the present invention onto the insulating layer and into the grooves; a step of exposing the coating film of the photosensitive conductive paste to light in correspondence with the grooves; and developing the exposed photosensitive conductive paste coating to form a circuit pattern at a position corresponding to the groove, The method for producing a substrate having a circuit pattern is characterized in that the groove has a tapered side surface.

[0013] The present invention also provides a method for producing an inductor, characterized in that the method for producing a substrate provided with a circuit pattern of the present invention is included in the steps thereof. [Effects of the Invention]

[0014] The photosensitive conductive paste of the present invention makes it possible to produce a highly precise circuit pattern that shrinks little during firing. DETAILED DESCRIPTION OF THE INVENTION

[0015] <Photosensitive conductive paste> The photosensitive conductive paste of the present invention contains conductive particles (A) and a photosensitive organic component (B).

[0016] <Conductive particles (A)> The photosensitive conductive paste of the present invention contains conductive particles (A). Examples of conductive particles (A) include powders of metals such as silver, gold, copper, platinum, palladium, tin, nickel, aluminum, tungsten, molybdenum, ruthenium oxide, chromium, titanium, and indium, as well as alloys thereof, and carbon powder. Two or more of these may be contained. Among these, silver, copper, and gold are preferred from the viewpoint of conductivity, and silver is more preferred from the viewpoints of cost and stability.

[0017] It is important that the median diameter r of the particle size distribution of the conductive particles (A) is 3.0 μm or more and 6.0 μm or less. By making r 3.0 μm or more, preferably 3.5 μm or more, and more preferably 4.0 μm or more, the movement of the conductive particles (A) can be suppressed during the firing process, thereby reducing the amount of shrinkage during firing. Furthermore, it is possible to prevent the formation of fine patterns from becoming difficult due to a decrease in the light transmittance of the coating film during the exposure process, which can cause peeling during development. On the other hand, by making r 6.0 μm or less, preferably 5.5 μm or less, and more preferably 5.0 μm or less, it is possible to prevent the probability of contact between conductive powder particles during firing from increasing the volume resistivity of the conductive pattern. Furthermore, it is possible to improve the straightness of the wiring ends in fine wiring, thereby preventing short circuits between wirings.

[0018] In the present invention, the median diameter can be measured by a laser light scattering method using a particle size distribution analyzer ("Microtrac" HRA Model No. 9320-X100, manufactured by Nikkiso Co., Ltd.).

[0019] It is important that the content V1 of the conductive particles (A) in the total solid content is 37% by volume or more and 55% by volume or less. By making V1 37% by volume or more, preferably 40% by volume or more, and more preferably 42% by volume or more, the amount of solids lost during firing can be kept small, and the amount of shrinkage can be kept small. On the other hand, by making V1 55% by volume or less, preferably 52% by volume or less, and more preferably 50% by volume or less, it is possible to prevent a decrease in the light transmittance of the coating film during the exposure step, which makes it difficult to form a fine pattern.

[0020] In the present invention, the volume of the conductive particles (A), the volume of inorganic particles (C) other than the conductive particles (described later), and the volume of the solid content of the photosensitive organic component (B) are measured as follows. First, the paste is filtered to separate the mixture of conductive particles and inorganic particles from the solid content of the photosensitive organic component (B). The conductive powder and inorganic particles are classified, and the mass of each is measured. The organic component is dried at 100°C for 2 hours, and the mass after drying is measured. The volume can be calculated from the mass and density of each component.

[0021] <Photosensitive organic component (B)> The photosensitive conductive paste of the present invention contains a photosensitive organic component (B). In the present invention, the photosensitive organic component refers to a group of organic components that contain at least a component that changes or causes a change in properties in response to light. In other words, it is not necessary for all components constituting the photosensitive organic component of the present invention to contribute to photosensitivity.

[0022] The photosensitive organic component (B) preferably contains an alkali-soluble resin, a photopolymerization initiator, and a solvent. Here, the alkali-soluble resin refers to a resin having an alkali-soluble group. Examples of alkali-soluble groups include a carboxyl group, a phenolic hydroxyl group, a sulfonic acid group, and a thiol group. Among these, a carboxyl group is preferred because of its high solubility in an alkaline developer.

[0023] 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.

[0024] Examples of acrylic monomers 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; acrylates having a cyclic aromatic hydrocarbon group having 6 to 10 carbon atoms, such as benzyl acrylate, phenyl 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; Examples include those in which the acrylate is replaced with a methacrylate. Two or more of these may be used.

[0025] Examples of copolymerization components other than acrylic monomers include: Styrenics such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, chloromethylstyrene, and hydroxymethylstyrene; Examples thereof include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, and vinylacetic acid, and acid anhydrides thereof. Two or more of these may be used.

[0026] The acrylic resin preferably has a carbon-carbon double bond in the side chain or at the molecular end, 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.

[0027] Examples of methods for introducing a carbon-carbon double bond into an acrylic resin include a method in which a mercapto group, an amino group, a hydroxyl group, or a carboxyl group in the acrylic resin is reacted 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.

[0028] 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, and Cyclomer (registered trademark) M100 and A200 manufactured by Daicel Chemical Industries, Ltd. Two or more of these may be used.

[0029] 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.

[0030] The photopolymerization initiator is a compound that absorbs short wavelength light such as ultraviolet light and decomposes, or generates radicals through a hydrogen abstraction reaction.

[0031] 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.

[0032] Examples of photopolymerization initiators that generate radicals through a hydrogen abstraction reaction include benzophenone, anthraquinone, thioxanthone, phenylglyoxylic acid methyl ester, etc. Two or more of these may be contained.

[0033] The solvent wets or dissolves the components constituting the photosensitive conductive paste, and provides excellent coating properties.

[0034] Examples of solvents include N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethylimidazolidinone, dimethyl sulfoxide, diethylene glycol monoethyl ether, dipropylene glycol methyl ether, dipropylene glycol n-propyl ether, dipropylene glycol n-butyl ether, tripropylene glycol methyl ether, tripropylene glycol-n-butyl ether, diethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol phenyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, γ-butyrolactone, ethyl lactate, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, ethylene glycol mono-n-propyl ether, diacetone alcohol, tetrahydrofurfuryl alcohol, and propylene glycol monomethyl ether acetate. Two or more of these may be contained.

[0035] The photosensitive organic component (B) may contain a photosensitive monomer, a dispersant, a plasticizer, a leveling agent, a surfactant, a silane coupling agent, an antifoaming agent, a stabilizer, etc., to the extent that the desired properties are not impaired.

[0036] <Inorganic particles (C) other than conductive particles (A)> The photosensitive conductive paste of the present invention preferably further contains inorganic particles (C) other than the conductive particles (A). By containing such inorganic particles (C), sintering of the conductive particles (A) can be inhibited, and the amount of shrinkage during firing of the photosensitive conductive paste can be effectively suppressed.

[0037] The inorganic particles (C) preferably contain at least one selected from the group consisting of titania, alumina, silica, cordierite, mullite, spinel, barium titanate, and zirconia. Among these, alumina, titania, and silica are particularly preferred, and silica is more preferred from the viewpoint of microfabrication.

[0038] The inorganic particles (C) preferably have a median diameter of 1 to 100 nm in their particle size distribution. Having a median diameter of 1 nm or more in their particle size distribution inhibits sintering of the conductive powder particles, further reducing the amount of shrinkage. Having a median diameter of 100 nm or less reduces the resistance of the circuit pattern obtained after firing.

[0039] The volume ratio V2 of the inorganic particles (C) relative to 100 volume% of the conductive particles (A) is preferably 3 volume% or more and 10 volume% or less. By setting V2 to 3 volume% or more, more preferably 3.5 volume% or more, and even more preferably 4 volume% or more, it is possible to inhibit the movement of the conductive powder during firing and further reduce the amount of shrinkage during firing. On the other hand, by setting V2 to 10 volume% or less, more preferably 7 volume% or less, and even more preferably 5.5 volume% or less, it is possible to reduce the resistance value of the circuit pattern obtained after firing.

[0040] In the photosensitive conductive paste of the present invention, the product r×V1×V2 of r, V1, and V2 is preferably 500 or more and 3300 or less. By making r×V1×V2 500 or more, more preferably 600 or more, and even more preferably 700 or more, the amount of shrinkage during firing can be further reduced. On the other hand, by making r×V1×V2 3300 or less, more preferably 2500 or less, and even more preferably 1500 or less, it is possible to prevent a shrinkage rate mismatch with the dielectric layer due to insufficient shrinkage, and to prevent the occurrence of voids between the dielectric and the electrode.

[0041] <Production of photosensitive conductive paste> The photosensitive conductive paste of the present invention can be obtained, for example, by dissolving and / or dispersing conductive particles (A), a photosensitive organic component (B) other than the solvent, and preferably inorganic particles (C) in a solvent. Examples of the apparatus for dissolving and / or dispersing include a disperser such as a triple roller or a ball mill, and a kneader.

[0042] <Cured product> Next, the cured product of the present invention will be described. The cured product of the present invention is obtained by curing the photosensitive conductive paste of the present invention.

[0043] There are no particular restrictions on the shape of the cured product of the present invention.

[0044] The film thickness t of the cured product of the present invention is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of electrical conductivity, while from the viewpoint of fine pattern formation in a small area, it is preferably 35 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less.

[0045] The cured product may have a predetermined pattern, such as a stripe or spiral pattern.

[0046] The ratio t / w of the film thickness t to the line width w of the cured product is preferably 0.5 or more and 1.0 or less. By setting t / w to 0.5 or more and 1.0 or less, wiring with a high aspect ratio can be obtained, and both fine wiring and low resistance can be achieved.

[0047] Furthermore, the ratio b / a of the bottom width b to the top width a of the cured product is preferably 0.6 or more and 1.0 or less. By satisfying b / a of 0.6 or more and 1.0 or less, wiring with a large cross-sectional area and low resistance can be obtained.

[0048] The cured product can also be laminated to form a laminate. The number of laminated layers is preferably 1 to 30. By laminating one or more layers, the thickness of a predetermined pattern can be increased. On the other hand, by laminating 30 or less layers, the influence of misalignment between layers can be reduced.

[0049] <Production of cured product> The cured product can be obtained, for example, by applying the photosensitive conductive paste of the present invention to a substrate, drying the paste, and then photo-curing the paste by exposure to light. When a patterned cured product is to be produced, the pattern may be formed by pattern exposure followed by development.

[0050] Examples of the coating method in the coating step include spin coating using a spinner, spray coating, roll coating, screen printing, offset printing, gravure printing, letterpress printing, flexographic printing, and methods using a blade coater, die coater, calendar coater, meniscus coater, or bar coater. Among these, screen printing is preferred because it provides excellent surface flatness for the resulting coating film and allows easy film thickness adjustment by selecting a screen plate.

[0051] Drying methods include, for example, heat drying using a heating device such as an oven, hot plate, or infrared, and vacuum drying. The heating temperature is preferably 40 to 130°C. By setting the drying temperature to 40°C or higher, the solvent can be efficiently removed by evaporation. On the other hand, by setting the drying temperature to 130°C or lower, thermal crosslinking of the photosensitive conductive paste is suppressed, and residue in non-exposed areas in the exposure and development process described below is reduced, making it possible to easily form a more precise pattern. The heating time is preferably 5 minutes to 1 hour.

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

[0053] Examples of the developer 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, and hexamethylenediamine.

[0054] To these aqueous solutions, polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and γ-butyrolactone; 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 may be added.

[0055] Examples of the developing method include a method in which a developer is sprayed onto the exposed dry film while the substrate on which the dry film has been formed is left standing or rotated, a method in which the substrate on which the exposed dry film has been formed is immersed in a developer, and a method in which ultrasonic waves are applied to the substrate on which the exposed dry film has been formed while the substrate is immersed in a developer.

[0056] The cured product obtained by development may be subjected to a rinse treatment with a rinse solution, such as water, an aqueous solution of an alcohol such as ethanol or isopropyl alcohol, or an aqueous solution of an ester such as ethyl lactate or propylene glycol monomethyl ether acetate.

[0057] <Fired body> The fired body of the present invention is obtained by firing the above-mentioned photosensitive conductive paste of the present invention.

[0058] The firing method may include, for example, 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.

[0059] <Electronic components> The electronic component of the present invention includes the sintered body of the present invention and an insulating ceramic layer. The presence of the insulating ceramic layer can prevent unintended short circuits between the sintered bodies.

[0060] The insulating ceramic layer preferably has a composition, calculated as oxides, of SiO2 25-50 (mass%), Al2O3 30-60 (mass%), B2O3 5-20 (mass%), and K2O 0.3-3 (mass%). By using such a composition, it becomes easier to obtain the relative dielectric constant ε described below.

[0061] The dielectric constant ε of the insulating ceramic layer is preferably 3.0 or more and 6.0 or less. By setting ε to 6.0 or less, when an insulating ceramic layer with a circuit pattern is applied to a multilayer chip inductor, a high-performance inductor with low loss can be obtained. Furthermore, by setting ε to 3.0 or more, mechanical strength can be increased.

[0062] The electronic component of the present invention may have terminal electrodes on the outside of the sintered body and the insulating ceramic layer, and examples of materials for the terminal electrodes include nickel and tin.

[0063] <Method for manufacturing an insulating ceramic layer with a circuit pattern> One method for producing an insulating ceramic layer having a circuit pattern of the present invention includes a coating step of applying the photosensitive conductive paste of the present invention onto an insulating ceramic layer to obtain a coating film, a step of drying the coating film to obtain a dry film, and a step of exposing and developing the dry film to obtain a circuit pattern.

[0064] First, the photosensitive conductive paste of the present invention is applied onto an insulating ceramic layer to obtain a coating film.

[0065] The insulating ceramic layer can be obtained by applying an insulating ceramic composition or a photosensitive insulating ceramic composition to the entire surface or part of a transparent film made of a resin such as alumina, quartz glass, soda glass, chemically strengthened glass, "Pyrex" (registered trademark) glass, synthetic quartz plate, epoxy resin substrate, polyetherimide resin substrate, polyether ketone resin substrate, polysulfone resin substrate, polyethylene terephthalate film (hereinafter referred to as "PET film"), cycloolefin polymer film, polyimide film, polyester film, or aramid film, or an optical resin plate, followed by drying.

[0066] As a coating method, a screen printing method, a bar coater, a roll coater, a die coater, a blade coater, or the like can be used.

[0067] When a photosensitive insulating ceramic composition is used, the pattern may be formed by photolithography.

[0068] The insulating ceramic composition preferably contains an insulating ceramic powder, a binder resin, and a solvent. Examples of insulating ceramic powders include "Palceram" (registered trademark) BT149 (product name; manufactured by Nippon Chemical Industry Co., Ltd.), L5 (product name; manufactured by Ferro Corp.), and SG-200 (product name; manufactured by Nippon Talc Co., Ltd.). Two or more of these may be contained. Examples of binder resins include acrylic resin, polyvinyl butyral resin, polyvinyl alcohol resin, cellulose resin, and methyl cellulose resin. Two or more of these may be contained.

[0069] As the solvent for the insulating ceramic composition, the solvent contained in the photosensitive organic component (B) of the photosensitive conductive paste described above is preferably used.

[0070] The photosensitive insulating ceramic composition preferably contains an alkali-soluble resin and a photopolymerization initiator in addition to the insulating ceramic powder and solvent.

[0071] As the alkali-soluble resin and photopolymerization initiator used in the photosensitive insulating ceramic composition, the alkali-soluble resin and photopolymerization initiator contained in the photosensitive organic component (B) of the photosensitive conductive paste described above are preferably used.

[0072] The coating step of applying the photosensitive conductive paste onto the insulating ceramic layer to obtain a coating film may be carried out by the methods exemplified as the coating method in the method for producing the cured product described above.

[0073] Next, the coated film is dried to obtain a dry film.

[0074] The drying method in the drying step may be the same as the drying method in the above-mentioned method for producing a cured product.

[0075] The dried film is then exposed and developed to obtain a circuit pattern.

[0076] Examples of the exposure method in the exposure and development step include the methods exemplified as the exposure method in the above-mentioned method for producing a cured product.

[0077] The dried film after exposure is developed using a developer to dissolve and remove the unexposed areas, thereby forming a desired pattern. Examples of the developer include those exemplified as the developer in the above-mentioned method for producing a cured product.

[0078] Examples of the developing method include a method in which a developer is sprayed onto the dried film after exposure while the insulating ceramic layer is left standing or rotated, a method in which the insulating ceramic layer having the dried film after exposure is immersed in a developer, and a method in which ultrasonic waves are applied to the insulating ceramic layer having the dried film after exposure while immersing it in a developer.

[0079] The pattern obtained by development may be subjected to a rinse treatment with a rinse liquid, such as those exemplified as the rinse liquid in the method for producing a cured product described above.

[0080] The insulating ceramic layers having the circuit patterns thus obtained can be stacked to form a laminate.

[0081] The insulating ceramic layer having the circuit pattern thus obtained is preferably fired to form a fired body. Firing methods include those exemplified as firing methods in the method for producing a fired body. The circuit pattern formed on the insulating ceramic layer is a composite containing a conductive powder (A) and a photosensitive organic component (B), and exhibits conductivity when the conductive powders (A) come into contact with each other during firing.

[0082] <Electronic component manufacturing method> One method for manufacturing an electronic component of the present invention includes a step of obtaining a plurality of insulating ceramic layers with circuit patterns by the method for manufacturing an insulating ceramic layer with circuit patterns of the present invention, a lamination step of stacking and thermocompression bonding the plurality of insulating ceramic layers with circuit patterns to obtain a laminate, and a firing step of firing the laminate.

[0083] First, a plurality of insulating ceramic layers having circuit patterns are obtained by the method for producing an insulating ceramic layer having circuit patterns of the present invention.

[0084] Next, the plurality of insulating ceramic layers with circuit patterns are stacked and thermocompression bonded to obtain a laminate. Examples of the stacking method include stacking the insulating ceramic layers with circuit patterns using guide holes. Examples of the thermocompression bonding device include a hydraulic press. The thermocompression bonding temperature is preferably 90 to 130°C, and the thermocompression bonding pressure is preferably 5 to 20 MPa.

[0085] Next, the laminate is fired. As the firing method, the methods exemplified as the firing method in the above-mentioned method for producing a fired body can be mentioned.

[0086] One method for producing an electronic component of the present invention includes a step of obtaining a laminate by repeating the following steps A to F in this order multiple times on an insulating ceramic layer with a circuit pattern obtained by the method for producing an insulating ceramic layer with a circuit pattern of the present invention, and a step of firing the laminate. Step A: A step of applying a photosensitive insulating ceramic composition to obtain a coating film Step B: A step of drying the coating film to obtain a dry film. Step C: A step of exposing and developing the dried film to obtain an insulating ceramic layer. Step D: A step of applying the photosensitive conductive paste of the present invention onto the insulating ceramic layer to obtain a coating film. Step E: A step of drying the coating film to obtain a dry film. Step F: A step of exposing and developing the dried film to obtain a circuit pattern.

[0087] First, in step A, a photosensitive insulating ceramic composition is applied to an insulating ceramic layer having a circuit pattern obtained by the method for producing an insulating ceramic layer having a circuit pattern of the present invention to obtain a coating film. As the photosensitive insulating ceramic composition, the photosensitive insulating ceramic composition used in the method for producing an insulating ceramic layer having a circuit pattern described above can be used. Examples of the coating method include the methods exemplified as the coating method in the method for producing a cured product described above.

[0088] Next, in step B, the resulting coated film of the photosensitive insulating ceramic composition is dried to obtain a dried film. Examples of the drying method include the methods exemplified as the drying method in the above-mentioned method for producing a cured product.

[0089] Next, in step C, the obtained dried film is exposed to light and developed to obtain an insulating ceramic layer. Examples of the exposure method include the methods exemplified as the exposure method in the above-mentioned method for producing a cured product. Examples of the development method include the methods exemplified as the development method in the above-mentioned method for producing a cured product.

[0090] Next, in step D, the photosensitive conductive paste of the present invention is applied onto the obtained insulating ceramic layer to obtain a coating film.

[0091] Next, in step E, the resulting coated film of the photosensitive conductive paste is dried to obtain a dried film.

[0092] Next, in step F, the resulting dried film is exposed to light and developed to obtain a circuit pattern.

[0093] Next, the above-described steps A to F are repeated in this order multiple times to obtain a laminate.

[0094] Next, the resulting laminate is fired by the method exemplified above as the firing method for the fired body.

[0095] <Method of manufacturing a circuit-patterned substrate> The method for manufacturing a circuit patterned substrate of the present invention includes the steps of applying a photosensitive insulating ceramic composition to a substrate, exposing the coating of the photosensitive insulating ceramic composition to light in a desired pattern, developing the exposed coating of the photosensitive insulating ceramic composition to form an insulating layer having grooves, applying the photosensitive conductive paste of the present invention onto the insulating layer and into the grooves, exposing the coating of the photosensitive conductive paste to light corresponding to the grooves, and developing the exposed coating of the photosensitive conductive paste to form a circuit pattern in a position corresponding to the grooves, and it is preferable that the grooves have tapered sides.

[0096] Because the grooves have tapered sides, air bubbles can easily escape when applying and filling the photosensitive conductive paste into the grooves, even when the paste contains conductive powder with a large particle size, and conductivity close to that expected from the design can be obtained.

[0097] The ratio (d / c) of the top width (c) to the bottom width (d) of the tapered groove is preferably 0.30 or more and less than 1.00. By making it less than 1.00, more preferably 0.95 or less, and even more preferably 0.90 or less, the filling ability of the photosensitive conductive paste can be improved. Furthermore, by making it 0.3 or more, more preferably 0.5 or more, and even more preferably 0.7 or more, the cross-sectional area of ​​the circuit pattern can be increased.

[0098] The viscosity of the photosensitive conductive paste is preferably 3 to 50 Pa·s. By setting the viscosity to 50 Pa·s or less, more preferably 40 Pa·s or less, and even more preferably 30 Pa·s or less, it becomes easier to fill tapered grooves. Furthermore, by setting the viscosity to 3 Pa·s or more, more preferably 5 Pa·s or more, and even more preferably 10 Pa·s or more, it becomes easier to apply the paste.

[0099] The viscosity of the photosensitive conductive paste is measured using a Brookfield type viscometer at 10 rpm.

[0100] The TI value (thixotropic index) of the photosensitive conductive paste is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.3 or less, which allows for excellent leveling properties and excellent filling properties into grooves.

[0101] The TI value of a photosensitive conductive paste is defined as the ratio (e / f) of the value (e) measured at 10 rpm and the value (f) measured at 30 rpm using a Brookfield viscometer.

[0102] The coating film, in which a photosensitive conductive paste is applied onto the insulating layer and into the grooves, is exposed to light corresponding to the grooves. Examples of exposure methods include proximity exposure, in which exposure is performed through a mask, and direct pattern writing using laser light.

[0103] The opening width of the exposure mask when performing proximity exposure is preferably equal to or smaller than the width (top width c) of the groove in the insulating layer, which allows for the formation of a circuit pattern with a higher aspect ratio.

[0104] The method for producing a substrate having a circuit pattern of the present invention is suitable for producing an inductor. That is, the method for producing an inductor of the present invention includes the method for producing a substrate having a circuit pattern of the present invention as a step.

[0105] The circuit patterned substrate obtained by the manufacturing method of the present invention can be cut into the desired chip size, 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.

[0106] By firing, the electrical conductivity of the circuit pattern can be developed to form a conductive pattern. Examples of the method for applying the terminal electrodes include sputtering. Examples of metals used for plating include nickel and tin. [Example]

[0107] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the embodiments shown here. It should be noted that Examples 8, 13, 14, and 15 should be read as Comparative Examples 7, 8, 9, and 10, respectively.

[0108] [Measurement and evaluation method] (1) Median diameter The particle size distribution 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.).

[0109] (2) High-definition pattern processability (Formation of insulating ceramic layer) The insulating ceramic powder was "Palceram" BT149 (manufactured by Nippon Chemical Industry Co., Ltd.) 100 parts by volume, and the binder resin was polyvinyl butyral resin (SP value 19.1 (J / cm3 ) 1 / 2 240 parts by volume of a ceramic paste, 80 parts by volume of dibutyl phthalate as a plasticizer, and 160 parts by volume of ethylene glycol monobutyl ether as a solvent were mixed and applied to an alumina substrate (100 mm × 100 mm × 0.5 mm thick) by the doctor blade method to form an insulating ceramic layer.

[0110] (Formation of coating film) The photosensitive conductive paste obtained in each of the examples and comparative examples was applied onto the insulating ceramic layer by screen printing so that the film thickness after drying would be 10 μm, thereby obtaining a coating film.

[0111] (Dry film formation) The resulting coating was dried for 10 minutes using a hot air dryer at 80°C to form a dry film on the insulating ceramic layer. The same procedure was repeated to prepare four substrates for each Example and Comparative Example, each with a dry film and an insulating ceramic layer.

[0112] (Pattern formation) The dried film was exposed to 21 mW / cm 2 exposure through four types of exposure masks with coil-shaped patterns having line widths / line spacings (hereinafter referred to as "L / S") of 20 μm / 20 μm, 18 μm / 18 μm, 15 μm / 15 μm, and 12 μm / 12 μm. 2 The output of the ultra-high pressure mercury lamp is 400mJ / cm 2 (equivalent to a wavelength of 365 nm) was used for exposure.

[0113] Thereafter, shower development was carried out using a 0.1% by mass aqueous solution of sodium carbonate as a developer until the unexposed areas were completely dissolved (hereinafter referred to as "total dissolution time"), thereby producing four types of pattern-forming sheets with different L / S.

[0114] The four types of pattern-formed sheets were each observed at a magnification of 10 times using an optical microscope, and evaluated based on the presence or absence of pattern peeling or short circuits according to the following criteria: D or higher was considered to be acceptable. A: No peeling or short circuits were observed in any of the four patterns of all sizes. B: No peeling or short circuiting was observed in a pattern of 15 μm / 15 μm or more, and peeling or short circuiting was observed in a pattern of 12 μm / 12 μm or less. C: No peeling or short circuiting was observed in a pattern of 18 μm / 18 μm or more, and peeling or short circuiting was observed in a pattern of 15 μm / 15 μm or less. D: No peeling or short circuiting was observed in a pattern of 20 μm / 20 μm or more, but peeling or short circuiting was observed in a pattern of 18 μm / 18 μm or less. E: Peeling or short circuits are observed in all four patterns of all sizes.

[0115] (3) Volume resistivity The photosensitive conductive paste obtained in each Example and Comparative Example was applied to an alumina substrate (100 mm × 100 mm × 0.5 mm thick) by screen printing so that the film thickness after drying would be 10 μm. The resulting coating film was dried in a hot air dryer at 80°C for 10 minutes to obtain a dried film.

[0116] Exposure and development were carried out in the same manner as in the "High-definition pattern processability" section above, except that an exposure mask with a predetermined pattern (5 cm long x 1 mm line width, with 1 cm square pads on both ends) was used, to obtain a pattern-forming sheet for resistance measurement.

[0117] The obtained pattern-formed sheet for resistance measurement was sintered by heat treatment at 880° C. for 10 minutes to obtain a sintered body having a pattern-formed sheet for resistance measurement.

[0118] The obtained fired body with the pattern for resistance measurement was observed at 1000x magnification using an optical microscope to measure the line width of the fired body, and the film thickness of the fired body was measured using a stylus-type step gauge ("Surfcom" (registered trademark) 1400; manufactured by Tokyo Seimitsu Co., Ltd.). In addition, the resistance value of the fired body with the pattern for resistance measurement was measured using a digital multimeter (CDM-16D; manufactured by Custom Co., Ltd.), and the volume resistivity was calculated using the following formula. Volume resistivity (μΩ·cm) = Actual resistance value (Ω) × 10 6× Pattern line width (cm) × Pattern thickness (cm) ÷ Pattern length (cm) ... (formula).

[0119] Evaluation was based on the following criteria, with C or above being considered a pass. A: The volume resistivity is less than 2.2 μΩ·cm. B: The volume resistivity is 2.2 μΩ·cm or more and less than 2.5 μΩ·cm. C: The volume resistivity is 2.5 μΩ·cm or more and less than 3.0 μΩ·cm. D: The volume resistivity is 3.0 μΩ·cm or more.

[0120] (4) Firing shrinkage The photosensitive conductive paste obtained in each Example and Comparative Example was applied to an alumina substrate (100 mm × 100 mm × 0.5 mm thick) by screen printing so that the film thickness after drying would be 10 μm. The resulting coating film was dried in a hot air dryer at 80°C for 10 minutes to obtain a dried film.

[0121] Using a mask with a coil-shaped pattern L / S of 20 μm / 20 μm, exposure and development were carried out in the same manner as in the above-mentioned "high-definition pattern processability" to obtain a pattern-formed sheet for shrinkage rate measurement.

[0122] The resulting pattern-formed sheet for shrinkage measurement was observed under an optical microscope at a magnification of 1000 times to measure the pattern line width before firing. In addition, the pattern film thickness before firing was measured using a stylus-type step profiler ("Surfcom" (registered trademark) 1400; manufactured by Tokyo Seimitsu Co., Ltd.).

[0123] Thereafter, the pattern-formed sheet for shrinkage measurement was sintered by heat treatment at 880° C. for 10 minutes to obtain a pattern-formed sintered body for shrinkage measurement.

[0124] The resulting pattern-formed fired body for shrinkage measurement was observed at 1000x magnification using an optical microscope to measure the pattern line width after firing. Furthermore, the pattern film thickness after firing was measured using a stylus-type step gauge ("Surfcom" (registered trademark) 1400; manufactured by Tokyo Seimitsu Co., Ltd.). The firing shrinkage was calculated using the following formula: Line width change rate (%) = [pattern line width after firing (μm) / pattern line width before firing (μm)] × 100 Film thickness change rate (%) = [pattern film thickness after firing (μm) / pattern film thickness before firing (μm)] × 100 Firing shrinkage rate (%)=100−(line width change rate (%)×film thickness change rate (%)) / 100.

[0125] The evaluation was based on the following criteria, with D or above being considered a pass. A: The firing shrinkage rate is less than 55.0%. B: The firing shrinkage rate is 55.0% or more and less than 58.0%. C: The firing shrinkage rate is 58.0% or more and less than 60.0%. D: The firing shrinkage rate is 60.0% or more and less than 63.0%. E: The firing shrinkage rate is 63.0% or more.

[0126] (5) Observation and evaluation of circuit pattern cross sections The cross sections of the circuit-patterned substrates obtained in Examples 16 to 20 and Comparative Examples 5 and 6 were cut in the line width direction of the circuit pattern. The cross sections were observed at a magnification of 3000x using a scanning electron microscope (S2400; manufactured by Hitachi, Ltd.), and the thickness of the insulating layer, the top width c of the groove, the bottom width d, and the voids between the circuit pattern and the insulating layer were observed. Ten cross sections of the grooves at different locations were observed, and the number of cross sections out of the ten in which voids of 5 μm or more were observed was scored, with a score of 3 or less being considered acceptable. The size of the voids was calculated by measuring the longest part of the void (the distance between the two furthest ends of one void).

[0127] (6) Evaluation of the aspect ratio and resistance of the conductive pattern Substrates were fabricated in the same manner as in Examples 16 to 20 and Comparative Examples 5 and 6, except that the length of the grooves in the insulating layer and the circuit pattern was 40 mm. The resulting circuit-patterned substrate was fired by heat treatment at 880°C for 10 minutes to obtain a conductive pattern. The resistance of the conductive pattern was measured using a digital multimeter (CDM-16D; manufactured by Custom). The conductive pattern was then cut in the line width direction. The cross section was observed at a magnification of 3000 times using a scanning electron microscope (S2400; manufactured by Hitachi, Ltd.), and the line width and height of the conductive pattern were measured. The line width was defined as the maximum width of the cross section of the conductive pattern. The sheet resistance and the aspect ratio of the conductive pattern were calculated from the obtained results. The sheet resistance was calculated using the following formula. Sheet resistance (mΩ) = Conductive pattern resistance (mΩ) × Line width (mm) ÷ Conductive pattern length (mm) Less than 3.5mΩ was considered a pass.

[0128] (Photosensitive conductive paste) The raw materials used for the photosensitive conductive paste are as follows:

[0129] Conductive particles (A) A-1: Median diameter r is 3.2 μm, density is 10.5 g / cm 3 Ag powder A-2: r is 4.5 μm, density is 10.5 g / cm 3 Ag powder A-3: r is 5.2 μm, density is 10.5 g / cm 3 Ag powder A-4: r is 5.8 μm, density is 10.5 g / cm 3 Ag powder A-5: r is 2.8 μm, density is 10.5 g / cm 3 Ag powder A-6: r is 6.5 μm, density is 10.5 g / cm 3 of Ag powder.

[0130] Alkali-soluble resin: acrylic resin (weight-average molecular weight 30,000, glass transition temperature 110°C, acid value 100 mgKOH / g, density 1.0 g / cm) prepared by addition reaction of 40 mole parts of glycidyl methacrylate with 100 mole parts of carboxyl groups of a copolymer of methacrylic acid / methyl methacrylate / styrene in a molar ratio of 54 / 23 / 23. 3 ).

[0131] Photosensitive monomer: urethane acrylate containing an ester structure ("NK Oligo" UA-122P, manufactured by Shin-Nakamura Chemical Co., Ltd., viscosity 7.0 Pa s, weight-average molecular weight 1,100, density 1.0 g / cm 3 ).

[0132] Photopolymerization initiator: Oxime-based photopolymerization initiator (ADEKA Corporation "ADEKA Optomer" N-1919, density 1.3 g / cm 3 ).

[0133] Leveling agent: "Disparlon" (registered trademark) L-1980N (density 1.0 g / cm 3 ; manufactured by Kusumoto Chemical Co., Ltd.).

[0134] Dispersant: "Floren" G-700 (density 1.1 g / cm 3 (manufactured by Kyoeisha Chemical Co., Ltd.).

[0135] Solvent: "Cellul" CHXA (cyclohexanol acetate, density 1.0 g / cm 3 ;Manufactured by Daicel Corporation).

[0136] Inorganic particles (C) C-1: Silica (Nippon Aerosil Co., Ltd. "AEROSIL" R972, median diameter 12 nm, density 2.2 g / cm 3 ) C-2: Alumina (Nippon Aerosil Co., Ltd. "AEROXIDE" AluC, median diameter 13 nm, density 3.3 g / cm 3 ).

[0137] [Example 1] 5.0 g of alkali-soluble resin, 2.4 g of NK Oligo UA-122P, 0.5 g of Adeka Optomer N-1919, 0.1 g of "Disparlon" L-1980N, 0.1 g of Floren G-700, and 11.9 g of "Cellul" CHXA were mixed to prepare 20.0 g of photosensitive organic component B-1 (specific gravity 1.0 g / cm). 3 The composition is shown in Table 1.

[0138] 20.0 g of the obtained photosensitive organic component (B-1), 51.8 g of Ag powder (A-3), and 0.5 g of inorganic particles (C-1) were mixed and kneaded using a triple roller to obtain the photosensitive conductive paste P-1 shown in Table 2. The evaluation results are shown in Table 2.

[0139] [Examples 2 to 15, Comparative Examples 1 to 4] Photosensitive conductive pastes P-2 to P-19 having the compositions shown in Tables 2 to 4 were prepared in the same manner as in Example 1.

[0140] Evaluation of high-definition pattern processability: In Example 4, peeling was observed only in the 12 μm / 12 μm pattern. In Example 5, peeling was observed only in patterns of 15 μm / 15 μm or less. In Example 6, short circuits were observed only in the 12 μm / 12 μm pattern. In Example 7, short circuits were observed only in patterns of 15 μm / 15 μm or less. In Example 8, peeling was observed only in patterns of 15 μm / 15 μm or less. In Example 13, peeling was observed only in patterns of 15 μm / 15 μm or less. In Example 14, peeling was observed only in patterns of 15 μm / 15 μm or less. In Example 15, peeling was observed only in patterns of 18 μm / 18 μm or less. In Comparative Example 2, peeling was observed in all four patterns of different sizes. In Comparative Example 3, peeling was observed only in patterns of 18 μm / 18 μm or less. In Comparative Example 4, short circuits were observed in all four patterns of different sizes.

[0141] The evaluation results are shown in Tables 2 to 4.

[0142] [Examples 16 to 20, Comparative Examples 5 and 6] (base material) An alumina plate was used as the substrate.

[0143] (Photosensitive insulating composition) The mixture consisted of 55 parts by mass of insulating ceramic powder (L5 manufactured by Ferro Corp.), 20 parts by mass of an acrylic resin (weight average molecular weight 30,000, glass transition temperature 110°C, acid value 100 mgKOH / g) obtained by addition reaction of 40 mole parts of glycidyl methacrylate with 100 mole parts of carboxyl groups of a copolymer of methacrylic acid / methyl methacrylate / styrene in a molar ratio of 54 / 23 / 23, and a photopolymerization initiator ("Ade" manufactured by ADEKA Corporation). 7.0 parts by mass of "Kaoptomer" N-1919), 1.0 part by mass of a leveling agent ("Florene" G-700, manufactured by Kyoeisha Chemical Co., Ltd.), 1.0 part by mass of a dispersant ("Florene" G-700, manufactured by Kyoeisha Chemical Co., Ltd.), 4.0 parts by mass of dibutyl phthalate as a plasticizer, and 12.0 parts by mass of a solvent ("Cellul" CHXA, manufactured by Daicel Corporation) were weighed, mixed, and kneaded with three rollers to obtain photosensitive insulating composition I-1.

[0144] (Photosensitive conductive paste) Photosensitive conductive paste P-3 was used.

[0145] (circuit patterned board) Photosensitive insulating composition I-1 was applied onto a substrate so as to form an insulating layer with a thickness shown in Table 5, and then dried.

[0146] Next, an exposure mask was placed above the coating of the photosensitive insulating composition at a gap shown in Table 5, and full-line exposure was carried out at the exposure dose shown in Table 5 using an exposure device.

[0147] Next, the substrate was immersed in a 0.2 mass % Na2CO3 solution for the time shown in Table 5 to carry out development.

[0148] Next, a rinse treatment was carried out with ultrapure water.

[0149] Next, the photosensitive conductive paste was applied onto the insulating layer having the grooves to the maximum thickness of the coating shown in Table 5 (the distance from the bottom of the insulating layer groove into which the photosensitive conductive paste had entered to the surface of the photosensitive conductive paste coating, i.e., roughly corresponding to the height of the circuit pattern), and then dried.

[0150] Next, a mask having an opening width shown in Table 5 was placed above the coating of the photosensitive conductive composition, and an exposure dose of 400 mJ / cm 2 was applied using an exposure device. 2 The insulating layer was exposed to light at a wavelength of 365 nm in the areas corresponding to the grooves.

[0151] Next, the substrate was immersed in a 0.2 mass % Na2CO3 solution for 30 seconds to carry out development.

[0152] Then, a rinsing treatment was carried out with ultrapure water to obtain a substrate with a circuit pattern.

[0153] [Table 1]

[0154] [Table 2]

[0155] [Table 3]

[0156] [Table 4]

[0157] [Table 5]

Claims

1. The conductive particles (A), the photosensitive organic component (B), and the inorganic particles (C) other than the conductive particles (A) are contained, the photosensitive organic component (B) contains an alkali-soluble resin, a photosensitive monomer, and a photopolymerization initiator; the median diameter r of the particle size distribution of the conductive particles (A) is 3.0 μm or more and 6.0 μm or less; The content V of the conductive particles (A) in the total solid content １ is 37% by volume or more and 55% by volume or less, the median diameter of the particle size distribution of the inorganic particles (C) is 1 to 100 nm, The amount V of the inorganic particles (C) relative to 100% by volume of the conductive particles (A) ２ The photosensitive conductive paste has a content of 3% by volume or more and 10% by volume or less.

2. The r and V １ , V ２ The product r × V １ ×V ２ 2. The photosensitive conductive paste according to claim 1, wherein the viscosity is 500 or more and 3,300 or less.

3. The r and V １ , V ２ The product r × V １ ×V ２ 2. The photosensitive conductive paste according to claim 1, wherein the average particle diameter (r) of the conductive particles (A) is 500 or more and 3,300 or less, and the median diameter (r) of the particle diameter distribution of the conductive particles (A) is 3.5 μm or more.

4. 4. The photosensitive conductive paste according to claim 1, wherein the inorganic particles (C) contain at least one selected from the group consisting of titania, alumina, silica, cordierite, mullite, spinel, and barium titanate.

5. A cured product obtained by curing the photosensitive conductive paste according to any one of claims 1 to 4.

6. The cured product according to claim 5 , having a film thickness t of 10 μm or more and 35 μm or less.

7. The cured product according to claim 5 or 6, wherein the ratio t / w of the film thickness t to the line width w is 0.5 or more and 1.0 or less.

8. The cured product according to any one of claims 5 to 7, wherein the ratio b / a of the bottom width b to the top width a is 0.6 or more and 1.0 or less.

9. A method for producing an insulating ceramic layer having a circuit pattern, comprising the steps of: applying the photosensitive conductive paste according to any one of claims 1 to 4 onto an insulating ceramic layer to obtain a coating film; drying the coating film to obtain a dry film; and exposing and developing the dry film to obtain a circuit pattern.

10. 10. A method for manufacturing an electronic component, comprising: a step of obtaining a plurality of insulating ceramic layers with a circuit pattern by the method for manufacturing an insulating ceramic layer with a circuit pattern according to claim 9; a lamination step of laminating and thermocompression-bonding the plurality of insulating ceramic layers with a circuit pattern to obtain a laminate; and a firing step of firing the laminate.

11. A method for producing an electronic component, comprising: a step of repeating the following steps A to F in this order a plurality of times on an insulating ceramic layer having a circuit pattern obtained by the method for producing an insulating ceramic layer having a circuit pattern according to claim 9 to obtain a laminate; and a step of firing the laminate. Step A: A step of applying a photosensitive insulating ceramic composition to obtain a coating film Step B: A step of drying the coating film to obtain a dry film Step C: A step of exposing and developing the dried film to obtain an insulating ceramic layer. Step D: A step of applying the photosensitive conductive paste according to any one of claims 1 to 4 onto the insulating ceramic layer to obtain a coating film. Step E: A step of drying the coating film to obtain a dried film Step F: A step of exposing and developing the dried film to obtain a circuit pattern

12. applying a photosensitive insulating ceramic composition to a substrate; a step of exposing the coating film of the photosensitive insulating ceramic composition to light in a desired pattern; a step of developing the exposed coating film of the photosensitive insulating ceramic composition to form an insulating layer having grooves; a step of applying the photosensitive conductive paste according to any one of claims 1 to 4 onto the insulating layer and into the grooves; a step of exposing the coating film of the photosensitive conductive paste to light in correspondence with the grooves; and developing the exposed photosensitive conductive paste coating to form a circuit pattern at a position corresponding to the groove, A method for producing a substrate having a circuit pattern, wherein the groove has a tapered side surface.

13. The method for producing a substrate having a circuit pattern according to claim 12, wherein the ratio d / c of ​​the bottom width d to the top width c of the groove is 0.30 or more and less than 1.

00.

14. 14. The method for manufacturing a circuit patterned substrate according to claim 12, wherein the viscosity of the photosensitive conductive paste in the step of applying the photosensitive conductive paste onto the insulating layer and into the grooves is 3 to 50 Pa·s.

15. The method for manufacturing a circuit patterned substrate according to any one of claims 12 to 14, wherein in the step of exposing the coating film of the photosensitive conductive paste, the exposure is carried out through an exposure mask having an opening width narrower than the top width A of the grooves in the insulating layer.

16. A method for manufacturing an inductor, comprising the method for manufacturing a substrate provided with a circuit pattern according to any one of claims 12 to 15.

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