JP7782264B2 - 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 - Google Patents

Description

The present invention relates to a photosensitive conductive paste, a cured product, a fired body, an electronic component, a method for manufacturing an insulating ceramic layer with a circuit pattern, and a method for manufacturing an electronic component.

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

International Publication No. 2019/202889

One example of a method for manufacturing 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 layers with the circuit pattern. However, when using the photosensitive conductive paste described in Patent Document 1, the amount of shrinkage is large when fired in areas where many circuit patterns are stacked, and the difference between the amount of shrinkage and the amount of shrinkage of the insulating ceramic layer is large, which poses a problem: the edges of the electronic component are prone to bending, chipping, and peeling between layers.

Therefore, the present invention aims to provide a photosensitive conductive paste that can form high-resolution circuit patterns and has a small amount of shrinkage when the circuit pattern is fired.

That is, the present invention provides a photosensitive conductive paste containing conductive particles (A) and a photosensitive organic component (B), wherein the conductive particles (A) have a median diameter r of 3.0 μm or more and 6.0 μm or less in particle size distribution, and the content _V1 of the conductive particles (A) in the total solid content is 37 vol% or more and 55 vol% or less.

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

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

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

The present invention also relates to a method for producing an insulating ceramic layer with a circuit pattern, which comprises 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.

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 dry 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 dry film to obtain a circuit pattern.

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.

The present invention also relates to a method for manufacturing an inductor, characterized in that the method for manufacturing a circuit patterned substrate of the present invention is included in the process.

The photosensitive conductive paste of the present invention makes it possible to create high-resolution circuit patterns that shrink little during firing.

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

<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 viewpoint of cost and stability.

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 ensuring that r is 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) during the firing process can be suppressed, thereby reducing the amount of shrinkage during firing. This also helps prevent the formation of fine patterns from becoming difficult due to a decrease in the transparency of the coating film during the exposure process, which can lead to peeling during development. On the other hand, by ensuring that r is 6.0 μm or less, preferably 5.5 μm or less, and more preferably 5.0 μm or less, the probability of contact between conductive powder particles during firing can be reduced, preventing an increase in the volume resistivity of the conductive pattern. Furthermore, the linearity of the wiring ends in fine wiring can be improved, preventing short circuits between wiring.

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

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 in the exposure step, which makes it difficult to form a fine pattern.

In the present invention, the volume of the conductive particles (A), the volume of inorganic particles (C) other than the conductive particles (described below), 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.

<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.

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 carboxyl groups, phenolic hydroxyl groups, sulfonic acid groups, and thiol groups. Of these, carboxyl groups are preferred due to their high solubility in alkaline developers.

As an alkali-soluble resin, an acrylic resin is preferred, and a copolymer of an acrylic monomer having a carbon-carbon double bond and another monomer is preferred.

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.

Examples of copolymerization components other than acrylic monomers include:
Styrenes 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.

Acrylic resins preferably have carbon-carbon double bonds in the side chains or molecular terminals, which can improve the curing reaction rate during exposure. Examples of structures with carbon-carbon double bonds include vinyl groups, allyl groups, acrylic groups, and methacrylic groups. Acrylic resins may contain two or more of these.

Methods for introducing carbon-carbon double bonds into acrylic resins include, for example, reacting mercapto groups, amino groups, hydroxyl groups, or carboxyl groups in the acrylic resin with compounds having a glycidyl group or an isocyanate group and a carbon-carbon double bond, such as acrylic acid chloride, methacrylic acid chloride, or allyl chloride.

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.

Examples of compounds having an isocyanate group and a carbon-carbon double bond include acryloyl isocyanate, methacryloyl isocyanate, acryloylethyl isocyanate, and methacryloylethyl isocyanate. Two or more of these may be used.

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

Examples of photopolymerization initiators that decompose 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; 2,4,6-trimethylbenzoyl-diphenyl ether; 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.

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

The solvent wets or dissolves the components that make up the photosensitive conductive paste, making it easy to apply.

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 used.

The photosensitive organic component (B) may contain photosensitive monomers, dispersants, plasticizers, leveling agents, surfactants, silane coupling agents, antifoaming agents, stabilizers, etc., to the extent that the desired properties are not impaired.

<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.

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, with silica being even more preferred from the standpoint of micro-processability.

The median diameter of the particle size distribution of the inorganic particles (C) is preferably 1 to 100 nm. Having a median diameter of 1 nm or more in the particle size distribution of the inorganic particles (C) inhibits sintering of the conductive powder particles and further reduces the amount of shrinkage. On the other hand, having a median diameter of 100 nm or less reduces the resistance value of the circuit pattern obtained after firing.

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, movement of the conductive powder during firing can be inhibited and the amount of shrinkage during firing can be further suppressed. 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, the resistance value of the circuit pattern obtained after firing can be reduced.

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 suppressed. On the other hand, by making r× _V1 × _V2 3300 or less, more preferably 2500 or less, and even more preferably 1500 or less, a shrinkage rate mismatch with the dielectric layer due to insufficient shrinkage can be prevented, and voids can be prevented from occurring between the dielectric and the electrode.

<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.

<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.

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

From the viewpoint of electrical conductivity, the film thickness t of the cured product of the present invention is preferably 5 μm or more, and more preferably 10 μm or more. On the other hand, from the viewpoint of the ability to form fine patterns on small areas, it is preferably 35 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less.

The cured product may have a predetermined pattern shape. Examples of pattern shapes include stripes and spirals.

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 having t/w of 0.5 or more and 1.0 or less, wiring with a high aspect ratio can be obtained, achieving both fine wiring and low resistance.

It is also preferable that the ratio b/a of the bottom width b to the top width a of the cured product is 0.6 or more and 1.0 or less. By satisfying the b/a ratio of 0.6 or more and 1.0 or less, wiring with a large cross-sectional area and low resistance can be obtained.

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

<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.

Examples of coating methods used in the coating process 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 produces excellent surface flatness for the coating film obtained and allows for easy film thickness adjustment by selecting the appropriate screen.

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, reducing residue in unexposed areas during the exposure and development process described below, making it easier to form higher-resolution patterns. The heating time is preferably 5 minutes to 1 hour.

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, etc. Exposure devices include, for example, stepper exposure machines and proximity exposure machines. Actinic rays used for exposure include, for example, near-ultraviolet light, ultraviolet light, electron beams, X-rays, and laser light, with ultraviolet light being preferred. Light sources for ultraviolet light include, for example, 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.

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, and hexamethylenediamine.

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, etc. may be added.

Examples of development methods include spraying a developer onto the exposed dry film while the substrate on which the dry film has been formed is left stationary or rotated, immersing the substrate on which the exposed dry film has been formed in a developer, and applying ultrasound to the substrate on which the exposed dry film has been formed while immersing it in a developer.

The cured product obtained by development may be rinsed with 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.

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

Examples of firing methods include heat treatment at 300 to 600°C for 5 minutes to several hours, followed by a further heat treatment at 850 to 900°C for 5 minutes to several hours.

<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.

The insulating ceramic layer preferably has a composition, calculated as oxides, of 25 to 50 (mass %) SiO ₂ , 30 to 60 (mass %) Al ₂ O ₃ , 5 to 20 (mass %) B ₂ O ₃ , and 0.3 to 3 (mass %) K ₂ O. By using such a composition, it becomes easier to obtain the relative dielectric constant ε described below.

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.

The electronic component of the present invention may have terminal electrodes on the outside of the sintered body and the insulating ceramic layer. Examples of materials that may be used to form the terminal electrodes include nickel and tin.

<Method for manufacturing an insulating ceramic layer having 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.

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

The insulating ceramic layer is 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 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, and then drying it.

Application methods that can be used include screen printing, bar coater, roll coater, die coater, and blade coater.

When a photosensitive insulating ceramic composition is used, patterns may be formed using photolithography.

The insulating ceramic composition preferably contains 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.

The solvent contained in the photosensitive organic component (B) of the aforementioned photosensitive conductive paste is preferably used as the solvent for the insulating ceramic composition.

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

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

Examples of the coating process for applying a photosensitive conductive paste onto an insulating ceramic layer to obtain a coating film include the methods exemplified as coating methods in the method for manufacturing the cured product described above.

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

Drying methods used in the drying process include the methods exemplified as drying methods in the aforementioned method for producing cured products.

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

Examples of exposure methods used in the exposure and development process include the methods exemplified as exposure methods in the aforementioned method for producing cured products.

The dried film after exposure can be developed using a developer to dissolve and remove the unexposed areas, forming the desired pattern. Examples of developers include those exemplified as developers in the aforementioned method for producing a cured product.

Examples of development methods include spraying a developer onto the dried film after exposure while the insulating ceramic layer is left standing or rotated, immersing the insulating ceramic layer with the dried film after exposure in a developer, and applying ultrasound while immersing the insulating ceramic layer with the dried film after exposure in a developer.

The pattern obtained by development may be rinsed with a rinse solution. Examples of rinse solutions include those exemplified as rinse solutions in the method for producing a cured product described above.

The resulting insulating ceramic layers with circuit patterns can also be stacked to form a laminate.

The resulting insulating ceramic layer with a circuit pattern is preferably fired to form a fired body. Firing methods include those exemplified as firing methods for the method for producing a fired body. The circuit pattern formed on the insulating ceramic layer is a composite containing conductive powder (A) and a photosensitive organic component (B), and electrical conductivity is achieved by contact between the conductive powders (A) during firing.

<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.

First, multiple insulating ceramic layers with circuit patterns are obtained using the method for manufacturing insulating ceramic layers with circuit patterns of the present invention.

Next, the multiple insulating ceramic layers with circuit patterns are stacked and thermocompressed to obtain a laminate. Examples of stacking methods include stacking the insulating ceramic layers with circuit patterns using guide holes. Examples of thermocompression devices include hydraulic presses. The thermocompression temperature is preferably 90 to 130°C, and the thermocompression pressure is preferably 5 to 20 MPa.

Next, the laminate is fired. Firing methods include those exemplified as firing methods in the above-mentioned method for producing a fired body.

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 having a circuit pattern obtained by the method for producing an insulating ceramic layer having 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 dry 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 dry film to obtain a circuit pattern.

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. The photosensitive insulating ceramic composition can be the same as the photosensitive insulating ceramic composition used in the method for producing an insulating ceramic layer having a circuit pattern described above. Examples of application methods include those exemplified as application methods in the method for producing a cured product described above.

Next, in step B, the resulting coating film of the photosensitive insulating ceramic composition is dried to obtain a dried film. Drying methods include those exemplified as drying methods in the method for producing the cured product described above.

Next, in step C, the resulting dried film is exposed to light and developed to obtain an insulating ceramic layer. Examples of exposure methods include those exemplified as exposure methods in the aforementioned method for producing a cured product. Examples of development methods include those exemplified as development methods in the aforementioned method for producing a cured product.

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

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

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

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

Next, the resulting laminate is fired. Firing methods include those exemplified as firing methods in the aforementioned method for producing a fired body.

<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.

Because the grooves have tapered sides, air bubbles can easily escape when applying and filling the photosensitive conductive paste into the grooves, even when using paste containing conductive powder with large particle sizes, and conductivity close to that expected from the design can be achieved.

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. Setting this ratio to less than 1.00, more preferably 0.95 or less, and even more preferably 0.90 or less, can improve the filling ability of the photosensitive conductive paste. Furthermore, setting this ratio to 0.3 or more, more preferably 0.5 or more, and even more preferably 0.7 or more can increase the cross-sectional area of the circuit pattern.

The viscosity of the photosensitive conductive paste is preferably 3 to 50 Pa·s. By setting the viscosity at 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 at 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 viscosity of the photosensitive conductive paste is measured using a Brookfield viscometer at 10 rpm.

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. This ensures excellent leveling and groove filling properties.

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.

A coating of photosensitive conductive paste is applied to the insulating layer and into the grooves, and then exposed to light that corresponds to the grooves. Exposure methods include proximity exposure, which involves exposing through a mask, and direct patterning using laser light.

When using proximity exposure, it is preferable to set the opening width of the exposure mask to be equal to or smaller than the width of the groove in the insulating layer (top width c). This allows for the formation of circuit patterns with a higher aspect ratio.

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

The circuit-patterned substrate obtained by the manufacturing method of the present invention can be cut to 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.

By firing, the electrical conductivity of the circuit pattern can be developed, forming a conductive pattern. Examples of methods for applying terminal electrodes include sputtering. Examples of metals used for plating include nickel and tin.

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

[Measurement and evaluation method]
(1) Median diameter: 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.).

(2) High-definition patterning (forming an insulating ceramic layer)
A mixture of 100 parts by volume of "Palceram" BT149 (manufactured by Nippon Chemical Industry Co., Ltd.) as insulating ceramic powder, 240 parts by volume of polyvinyl butyral resin (SP value 19.1 (J/cm ³ ) ^1/2 ) as binder resin, 80 parts by volume of dibutyl phthalate as plasticizer, and 160 parts by volume of ethylene glycol monobutyl ether as solvent was applied to an alumina substrate (100 mm × 100 mm × thickness 0.5 mm) by the doctor blade method to form an insulating ceramic layer.

(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.

(Formation of dry film)
The resulting coating film 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 each having a dry film and an insulating ceramic layer formed thereon for each Example and Comparative Example.

(Pattern formation)
The dried film was exposed to light from an ultra-high pressure mercury lamp with an output of 21 mW/cm 2 at an irradiation dose of 400 mJ/cm ² (equivalent to a wavelength of 365 nm) through four types of exposure masks with coil pattern 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.

Then, shower development was performed using a 0.1% by mass aqueous solution of sodium carbonate as the developer until all of the unexposed areas had dissolved (hereinafter referred to as the "total dissolution time"), and four types of pattern-forming sheets with different L/S were produced.

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 circuiting was 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, but 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, but 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 were observed in all four patterns of different sizes.

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

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 specified pattern (5 cm long x 1 mm line width, with 1 cm square pads on both ends) was used, and a pattern-forming sheet for resistance measurement was obtained.

The obtained pattern-forming sheet for resistance measurement was heat-treated and fired at 880°C for 10 minutes to obtain a pattern-forming fired body for resistance measurement.

The obtained fired body having the pattern for resistance measurement formed thereon was observed at a magnification of 1000 times using an optical microscope, the line width of the fired body was measured, 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 having 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).

The evaluation was based on the following criteria, with C or higher 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.

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

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 described above in "High-definition pattern processability," and a pattern-forming sheet for shrinkage rate measurement was obtained.

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

The pattern-forming sheet for shrinkage measurement was then heat-treated and fired at 880°C for 10 minutes to obtain a pattern-forming fired body for shrinkage measurement.

The resulting pattern-formed fired body for shrinkage measurement was observed at a magnification of 1000 times 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 profiler ("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.

The evaluation was based on the following criteria, with D or higher 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.

(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 evaluated as a score, 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 most distant ends of one void).

(6) Evaluation of the aspect ratio and resistance of the conductive pattern Substrates were prepared in the same manner as in Examples 16 to 20 and Comparative Examples 5 and 6, except that the length of the insulating layer groove and circuit pattern was 40 mm. The obtained circuit-patterned substrate was baked 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 3000x magnification 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 value (mΩ) = Conductive pattern resistance value (mΩ) × line width (mm) ÷ conductive pattern length (mm)
A resistance of less than 3.5 mΩ was considered to be acceptable.

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

Conductive particles (A)
A-1: Ag powder with a median diameter r of 3.2 μm and a density of 10.5 g/cm3 ^. A-2: Ag powder with r of 4.5 μm and a density of 10.5 g/ ^{cm3 .} A-3: Ag powder with r of 5.2 μm and a density of 10.5 g/cm3. A-4: Ag powder with r of 5.8 μm and a density of 10.5 g/ ^cm3. A-5: Ag powder with r of 2.8 μm and a density of 10.5 g/ ^cm3. A-6: Ag powder with r of 6.5 μm and a density of 10.5 g/ ^cm3 .

Alkali-soluble resin: an acrylic resin (weight average molecular weight 30,000, glass transition point 110°C, acid value 100 mgKOH/g, density 1.0 g/cm ³ ) 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.

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 ).

Photopolymerization initiator: oxime-based photopolymerization initiator ("Adeka Optomer" N-1919, manufactured by ADEKA Corporation, density 1.3 g/cm ³ ).

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

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

Solvent: "Cellutol" CHXA (cyclohexanol acetate, density 1.0 g/cm ³ ; manufactured by Daicel Corporation).

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

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

20.0 g of the resulting photosensitive organic component (B-1) was mixed with 51.8 g of Ag powder (A-3) and 0.5 g of inorganic particles (C-1) and kneaded using three rollers to obtain the photosensitive conductive paste P-1 described in Table 2. The evaluation results are shown in Table 2.

[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.

Regarding 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.

The evaluation results are shown in Tables 2 to 4.

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

(Photosensitive insulating composition)
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 point 110°C, acid value 100 mgKOH/g) obtained by addition reaction of 40 parts by mole of glycidyl methacrylate with 100 parts by mole of carboxyl group of a copolymer of methacrylic acid/methyl methacrylate/styrene in a molar ratio of 54/23/23, and a photopolymerization initiator ("Adeka" manufactured by ADEKA Corporation). Photosensitive insulating composition I-1 was obtained by weighing, mixing, and kneading with a triple roller. 7.0 parts 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).

(Photosensitive conductive paste)
Photosensitive conductive paste P-3 was used.

(circuit patterned board)
The photosensitive insulating composition I-1 was applied onto the substrate so as to give an insulating layer with a thickness shown in Table 5, and then dried.

Next, an exposure mask was placed above the coating of photosensitive insulating composition at the gap shown in Table 5, and full-line exposure was performed using an exposure device with the exposure amount shown in Table 5.

Next, the substrate was immersed in a 0.2 mass % Na ₂ CO ₃ solution for the time shown in Table 5 to perform development.

Then, a rinse was performed with ultrapure water.

Next, the photosensitive conductive paste was applied onto the insulating layer with the grooves to the maximum coating thickness shown in Table 5 (the distance from the bottom of the insulating layer grooves filled with the photosensitive conductive paste to the surface of the photosensitive conductive paste coating; i.e., roughly corresponding to the height of the circuit pattern), and then dried.

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

Next, the substrate was immersed in a 0.2 mass % Na ₂ CO ₃ solution for 30 seconds to perform development.

Then, a rinse treatment was performed with ultrapure water to obtain a substrate with a circuit pattern.

Claims (16)

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 _V1 of the conductive particles (A) in the total solid content 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,
A photosensitive conductive paste, wherein the amount _V2 of the inorganic particles (C) relative to 100% by volume of the conductive particles (A) is 3% by volume or more and 10% by volume or less. The photosensitive conductive paste according to claim 1 , wherein the product r×V ₁ ×V ₂ of r, V ₁ and V ₂ is 500 or more and 3,300 or less. 2. The photosensitive conductive paste according to claim 1, wherein the product r×V ₁ ×V ₂ of r, V ₁ and V ₂ is 500 or more and 3300 or less, and the median diameter r of the particle diameter distribution of the conductive particles (A) is 3.5 μm or more. The photosensitive conductive paste according to any one of claims 1 to 3, wherein the inorganic particles (C) contain at least one selected from the group consisting of titania, alumina, silica, cordierite, mullite, spinel, and barium titanate. A cured product obtained by curing the photosensitive conductive paste according to any one of claims 1 to 4. The cured product according to claim 5, having a film thickness t of 10 μm or more and 35 μm or less. The cured product according to claim 5 or 6, wherein the ratio t/w of film thickness t to line width w is 0.5 or more and 1.0 or less. 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. A method for producing an insulating ceramic layer with 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. A method for manufacturing an electronic component, comprising: 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 described in claim 9; a lamination step of laminating and thermocompression-bonding the plurality of insulating ceramic layers with circuit patterns to obtain a laminate; and a firing step of firing the laminate. 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 dry 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 dry film to obtain a circuit pattern. 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. The method for manufacturing a circuit patterned substrate 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 greater and less than 1.00. The method for manufacturing a circuit patterned substrate according to claim 12 or 13, 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. The method for manufacturing a circuit patterned substrate according to any one of claims 12 to 14, wherein in the step of exposing the photosensitive conductive paste coating, the exposure is performed through an exposure mask having an opening width narrower than the top width A of the grooves in the insulating layer. A method for manufacturing an inductor, comprising the method for manufacturing a circuit patterned substrate according to any one of claims 12 to 15.