JP6637087B2 - Photosensitive composition and its use - Google Patents

Description

  The present invention relates to a photosensitive composition and its use.

BACKGROUND ART Conventionally, there has been known a method of forming a conductive layer or a resin insulating layer on a substrate by photocuring using a photosensitive composition containing a photopolymerizable compound and a photopolymerization initiator (Patent Documents 1 to 4). 6).
For example, Patent Literature 1 discloses that a wiring pattern is formed on a substrate by a photolithography method including a film forming process, an exposure process, a development process, and a baking process. In such a method, first, in a film forming step, a photosensitive composition is applied to a substrate by a printing method or the like and dried to form a film. Next, in the exposure step, after a photomask having a predetermined opening pattern is placed on the formed film, the film is exposed through the photomask. Thus, the exposed portion of the film is light-cured. Next, in the developing step, the unexposed portions, which have been shielded from light by the photomask, are removed by corrosion with an alkaline etching solution. Then, the film-like body having the desired development pattern is fired in a firing step. According to such a method, a conductive layer having a higher definition pattern can be formed as compared with conventional various printing methods.

Patent No. 4437603 Patent No. 4095163 JP 2003-183401 A JP 2015-110745 A JP-A-2015-184631 Patent No. 5393402

  In recent years, various electronic devices have been rapidly reduced in size and performance, and electronic components mounted on the electronic devices have been required to be further reduced in size and density. Along with this, in manufacturing electronic components, it is required to reduce the thickness of the conductive layer as well as to reduce the resistance of the conductive layer. For example, it is required to form a conductive layer including a fine line-shaped wiring (hereinafter, sometimes referred to as “fine line”) in which the width (line width) of the wiring forming the conductive layer is 30 μm or less.

  However, according to the study of the present inventors, it has been difficult to form a fine line stably when a conventional photosensitive composition as described in the above-mentioned patent document is used. For example, the unexposed portion may not be completely removed in the developing process, and adjacent wirings may be connected to each other to cause a short circuit failure. In addition, if the time of the developing step is set to be long in order to suppress the occurrence of such a short-circuit failure, the exposed portion may be narrowed, and the developed pattern may be peeled or disconnected.

  It is considered that the above problem is caused by a short development margin. Here, the “development margin” refers to a defect such as peeling or disconnection from the point where the unexposed portion is completely removed in the developing step (breakpoint (BP)) to the exposed portion constituting the developed pattern. Represents the length of time until the occurrence of. That is, if the development margin is not sufficiently ensured, the unexposed portion is removed and the exposed portion immediately becomes thinned or disappears. For this reason, especially when forming a fine line, it is difficult to determine the timing of terminating the developing process. Therefore, from the viewpoint of process control, there has been a demand for a technique capable of securing a longer development margin (for example, 10 seconds or more) and forming a fine line with good reproducibility.

  The present invention has been made in view of the above, and an object of the present invention is to provide a photosensitive composition having a long development margin and capable of stably forming fine lines. Another related object is to provide a composite including a conductive film made of a dried product of the photosensitive composition. Another related object is to provide an electronic component including a conductive layer formed of a fired body of the photosensitive composition, and a method for manufacturing the same.

  According to the present invention, there is provided a photosensitive composition used for producing a conductive layer including a wiring having a line width of 30 μm or less. This photosensitive composition contains a conductive powder, a photopolymerizable compound, and a photopolymerization initiator. The photopolymerization initiator comprises at least the following two components: (1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide; (2) α-aminoalkylphenones; When the total amount of the agent is 100% by mass, the above (1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide accounts for 50% by mass or more.

  The photosensitive composition contains at least the two components (1) and (2) as a photopolymerization initiator. As a result, a longer development margin time can be ensured in the development process, and the fine line forming property of the exposed portion can be improved. As a result, a fine line having a line width of 30 μm or less can be formed with good reproducibility. Further, it is possible to suppress the occurrence of defects such as short-circuit failure, peeling, and disconnection, and to improve the yield.

  In a preferred embodiment disclosed herein, the mass ratio between (1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and (2) α-aminoacetophenone is 50:50 to 90: It is 10. As a result, the fine line forming property can be further improved, and the effects of the technology disclosed herein can be exhibited at a higher level. For example, even a conductive layer having a finer line can be formed with high accuracy.

  In a preferred embodiment disclosed herein, the mass ratio between (1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and (2) α-aminoacetophenone is 50:50 to 85: Fifteen. Thereby, the etching resistance of the exposed portion can be further improved, and the peeling of the conductive layer can be suppressed at a higher level.

  In a preferred embodiment disclosed herein, the ratio of the photopolymerization initiator is 2% by mass or less when the entire photosensitive composition is 100% by mass. As a result, at least one of an effect of securing a longer development margin time and an effect of better improving fine line formability is achieved.

  In a preferred embodiment disclosed herein, the photopolymerizable compound includes a photopolymerizable compound having a urethane bond. This makes it possible to make the conductive film made of the dried photosensitive composition excellent in flexibility and stretchability. Further, the etching resistance of the exposed portion can be further improved. As a result, the adhesion between the base material and the conductive layer can be improved, and occurrence of problems such as peeling can be suppressed at a higher level.

  In a preferred embodiment disclosed herein, the conductive powder includes silver-based particles. This makes it possible to realize a conductive layer having an excellent balance between cost and low resistance.

  In a preferred embodiment disclosed herein, the conductive powder is a core portion containing a metal material, and covers at least a part of the surface of the core portion, and a coating portion containing a ceramic material, and a core-shell particle having a coating portion containing a ceramic material. Including. As a result, the etching resistance of the exposed portion can be further improved, and the fine line forming property can be further improved. In addition, in applications where ceramic electronic components with a conductive layer on a ceramic substrate (ceramic substrate) are used, the durability of the ceramic electronic component is improved by increasing the integration between the ceramic substrate and the conductive layer. can do.

In a preferred embodiment disclosed herein, in the L ^* a ^* b ^* color system based on JIS Z 8781: 2013, the lightness L ^* of the conductive powder is 50 or more. Accordingly, in the exposure step, light can reach stably to a deep portion of the exposed portion, and a thick conductive layer can be stably realized.

  In a preferred embodiment disclosed herein, the photosensitive composition further includes an organic solvent having a boiling point of 150 ° C or higher and 250 ° C or lower. As a result, the storage stability of the photosensitive composition and the ease of handling during formation of the conductive film can be improved, and the drying temperature after printing can be kept low.

  Further, according to the present invention, there is provided a composite comprising a green sheet and a conductive film disposed on the green sheet and made of a dried body of the photosensitive composition.

  Further, according to the present invention, there is provided an electronic component provided with a conductive layer made of a fired body of the photosensitive composition. According to the photosensitive composition, fine lines can be stably realized. Therefore, an electronic component including a small and / or high-density conductive layer can be suitably realized.

  Further, according to the present invention, the method includes applying the photosensitive composition on a substrate, exposing and developing, and baking to form a conductive layer made of a fired body of the photosensitive composition. A method for manufacturing a component is provided. The photosensitive composition has a longer development margin. Therefore, by such a manufacturing method, an electronic component having a small and / or high-density conductive layer can be stably manufactured, and the yield can be improved.

It is sectional drawing which shows typically the structure of the multilayer chip inductor which concerns on one Embodiment. 4 is a graph showing a relationship between a content ratio of an initiator c and a line width of a wiring pattern.

  Hereinafter, preferred embodiments of the present invention will be described. In addition, matters other than matters specifically mentioned in this specification (for example, a photopolymerization initiator contained in a photosensitive composition) and matters necessary for carrying out the present invention (for example, a method for preparing a photosensitive composition, The method for forming a conductive film or a conductive layer, the method for manufacturing an electronic component, and the like) can be understood based on the technical contents taught by the present specification and general technical common knowledge of those skilled in the art. . The present invention can be implemented based on the contents disclosed in this specification and common technical knowledge in the field.

In the following description, the photosensitive composition is dried at a temperature equal to or lower than the boiling point of the photopolymerizable compound and the photopolymerization initiator, specifically, at approximately 200 ° C. or lower, for example, 100 ° C. or lower. Object) is referred to as a “conductive film”. The conductive film encompasses the entire unfired (before firing) film. The conductive film may be an uncured material before light curing or a cured material after light curing. In the following description, a sintered body (fired product) obtained by firing the photosensitive composition at a temperature equal to or higher than the sintering temperature of the conductive powder is referred to as a “conductive layer”. The conductive layer includes a wiring (linear body) and a wiring pattern.
In this specification, the notation “A to B” indicating a range means A or more and B or less.

<< photosensitive composition >>
The photosensitive composition disclosed herein is used for producing a conductive layer including fine-line wiring having a line width (line width) of 30 μm or less after firing. For example, it is preferably used for forming a conductive film including a portion having a line width (line width) of 30 μm or less. The photosensitive composition disclosed herein contains conductive powder, a photopolymerizable compound, and a photopolymerization initiator as essential components. Hereinafter, each component will be described in order.

<Conductive powder>
The conductive powder is a component that imparts electrical conductivity to a conductive layer obtained by baking the photosensitive composition. The conductive powder is not particularly limited, and one or two or more types can be appropriately selected from conventionally known ones according to, for example, the application. Preferred examples of the conductive powder include gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), aluminum (Al), nickel (Ni), ruthenium (Ru), and rhodium. (Rh), tungsten (W), iridium (Ir), osmium (Os) and other simple metals, and mixtures and alloys thereof. Examples of the alloy include silver alloys such as silver-palladium (Ag-Pd), silver-platinum (Ag-Pt), and silver-copper (Ag-Cu).

  In a preferred embodiment, the conductive powder contains silver-based particles. Silver is relatively inexpensive and has high electrical conductivity. Therefore, when the conductive powder contains silver-based particles, a conductive layer having an excellent balance between cost and low resistance can be realized. In the present specification, “silver-based particles” include all particles containing a silver component. Examples of the silver-based particles include a simple substance of silver, the silver alloy described above, and core-shell particles having the silver-based particles as a core.

  In another preferred aspect, the conductive powder comprises metal-ceramic core-shell particles. The metal-ceramic core-shell particles have a core portion containing a metal material and a coating portion covering at least a part of the surface of the core portion and containing a ceramic material. Ceramic materials are excellent in chemical stability, heat resistance, and durability. For this reason, by adopting the form of metal-ceramic core-shell particles, the stability of the conductive powder in the photosensitive composition can be further improved. In addition, the fine line formability can be further improved. In addition, in the use of manufacturing a ceramic electronic component, the durability and the durability of the ceramic electronic component can be improved by increasing the integrity and adhesion between the ceramic base material and the conductive layer.

  In the metal-ceramic core-shell particles, examples of the metal material constituting the core portion include the above-described metals alone, and mixtures and alloys thereof. Among them, silver-based particles are preferable for the above-mentioned reasons. In other words, the conductive powder preferably includes silver-ceramic core-shell particles.

  The ceramic material constituting the coating portion is not particularly limited, but for example, zirconium oxide (zirconia), magnesium oxide (magnesia), aluminum oxide (alumina), silicon oxide (silica), titanium oxide (titania) Oxide-based materials such as cerium oxide, cerium oxide (ceria), yttrium oxide (yttria), and barium titanate; composite oxide-based materials such as cordierite, mullite, forsterite, steatite, sialon, zircon, and ferrite; silicon nitride (Silicon nitride), nitride materials such as aluminum nitride (aluminum nitride); carbide materials such as silicon carbide (silicon carbide); and hydroxide materials such as hydroxyapatite. For example, in applications where a conductive layer is formed on a ceramic base material to manufacture a ceramic electronic component, a ceramic material of the same type as the ceramic base material or a type having excellent affinity is preferable.

  Although not particularly limited, the content ratio of the ceramic material in the metal-ceramic core-shell particles may be, for example, 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the metal material in the core portion. . The metal-ceramic core-shell particles can be produced by a conventionally known method. For example, as described in paragraphs 0025 to 0028 of Japanese Patent No. 5075222, which is a prior application of the present applicant, a metal material and an organic metal compound (for example, a metal alkoxide or a chelate compound) having a target metal element or oxidation It can be produced by reacting with a material sol.

Although not particularly limited, D ₅₀ particle size of the conductive powder is from consideration of the exposure performance in the exposure step, generally may is 1.0 to 5.0 m. D ₅₀ particle size to within the above range, to improve the exposure performance of the exposure portion, it is possible to form a fine line even more stably. In this specification, "D ₅₀ particle size" refers to the volume-based particle size distribution based on the laser diffraction scattering method, a particle diameter corresponding the small particle size side in the cumulative value of 50%.
By suppressing the aggregation of a photosensitive composition, from the viewpoint of improving the stability, _{D 50} particle size of the conductive powder is, for example, 1.5 [mu] m or more, 2.0 .mu.m or more, there at 2.5μm or more You may. You can also increase the fine wire forming, in view of or promoting densification and low resistance of the conductive layer, D ₅₀ particle size of the conductive powder is, for example, 4.5 [mu] m or less, there below 4.0μm You may.

Although not particularly limited, it is preferable that the particle size distribution of the entire conductive powder has multimodality. In other words, it may comprise a first conductive powder and the second conductive powder having different D ₅₀ particle size. Thus, as compared with the case the difference between the D ₅₀ particle size of the first conductive powder and the second conductive powder is small, thereby improving the denseness and filling properties of the conductive layer, suitably reduce electric resistance be able to. The first conductive powder and the _{D 50} particle size of the second conductive powder, may at least 0.5 [mu] m, typically 0.5 to 3.0 [mu] m, for example, located several 1.0~2.0μm . In one embodiment, _{D 50} particle size of the first conductive powder, there generally 3 to 5 [mu] m, for example in the range of 3.5～4.5Myuemu, the _{D 50} particle size of the second conductive powder, generally 1 It is good to be in the range of 3.5 μm, for example, 1.5-3 μm.

  Although not particularly limited, the shape of the conductive particles constituting the conductive powder is typically approximately spherical with an average aspect ratio (ratio of major axis / minor axis) of approximately 1 to 2, preferably 1 to 2. 1.5, for example 1 to 1.2 spherical. As a result, the exposure performance can be more stably realized. The conductive powder preferably has an average aspect ratio in the above range. In this specification, the “average aspect ratio” refers to an arithmetic average value of the aspect ratio calculated from an observation image obtained by observing a plurality of conductive particles with an electron microscope. Further, in the present specification, the term “spherical” refers to a form that can be generally regarded as a sphere (ball) as a whole, and is a term that can include an elliptical shape, a polygonal shape, a disc-shaped spherical shape, and the like.

Although not particularly limited, the entirety of the conductive powder preferably has a lightness L ^* of 50 or more in an L ^* a ^* b ^* color system based on JIS Z 8781: 2013. Thereby, in the exposure step, the irradiation light can reach the deep portion of the exposed portion stably, and, for example, a thick conductive layer having a film thickness of 5 μm or more, or even 10 μm or more can be stably realized. be able to. From such a viewpoint, the brightness L ^* of the conductive powder may be approximately 55 or more, for example, 60 or more. Lightness L ^* can be adjusted for example by the type and D ₅₀ particle size of the conductive powder mentioned above. The measurement of the lightness L ^* can be performed by, for example, a spectrophotometer conforming to JIS Z 8722: 2009.

  The conductive powder may have an organic surface treating agent attached to its surface. Organic surface treatment agent, for example, to improve the dispersibility of the conductive powder in the photosensitive composition, to increase the affinity with other components, to prevent surface oxidation of the metal constituting the conductive powder, It can be used for at least one of these purposes. Examples of the organic surface treating agent include fatty acids such as carboxylic acid, and benzotriazole compounds.

  Although not particularly limited, the proportion of the conductive powder in the entire photosensitive composition is preferably about 50% by mass or more, typically 60 to 95% by mass, for example, 70 to 90% by mass. By satisfying the above range, a conductive layer excellent in denseness and electric conductivity can be formed. Further, the handleability of the photosensitive composition and the workability when forming the conductive film can be improved.

<Photopolymerizable compound>
The photopolymerizable compound is a component that is polymerized and cured by active species generated by decomposition of a photopolymerization initiator described below. The polymerization reaction may be addition polymerization or ring-opening polymerization. The photopolymerizable compound typically has one or more unsaturated bonds and / or cyclic structures. The photopolymerizable compound includes a monomer, a polymer, and an oligomer. Of these, monomers are preferred. The photopolymerizable compound is not particularly limited, and one or two or more types can be appropriately selected from conventionally known ones according to, for example, the application and the type of the substrate. Preferred examples of the photopolymerizable compound include a radical polymerizable monomer having at least one unsaturated bond such as a (meth) acryloyl group and a vinyl group, and a cationic polymerizable monomer having a cyclic structure such as an epoxy group. Is mentioned.

  In a preferred embodiment, the photopolymerizable compound includes a (meth) acrylate monomer having a (meth) acryloyl group. By containing the (meth) acrylate monomer, the flexibility of the conductive layer and the followability to the base material can be improved. As a result, the occurrence of problems such as peeling and disconnection can be suppressed at a higher level. In this specification, “(meth) acryloyl” includes “methacryloyl” and “acryloyl”, and “(meth) acrylate” is a term including “methacrylate” and “acrylate”. The (meth) acrylate monomer is a monofunctional (meth) acrylate having one functional group per molecule, a polyfunctional (meth) acrylate having two or more functional groups per molecule, and a modified product thereof. Is included.

  Preferred examples of the (meth) acrylate monomer include triethylene glycol monoacrylate, triethylene glycol monomethacrylate, tetraethylene glycol monoacrylate, tetraethylene glycol monomethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, and dipentaerythritol pentaacrylate. And polyfunctional (meth) acrylates such as dipentaerythritol hexaacrylate, tripentaerythritol heptaacrylate, tripentaerythritol octaacrylate, tetrapentaerythritol nonaacrylate, and tetrapentaerythritol decaacrylate. Among them, from the viewpoint of enhancing photocurability, a monomer having 5 or more (meth) acryloyl groups per molecule is preferable.

  In another preferred embodiment, the photopolymerizable compound includes a photopolymerizable compound having a urethane bond (—NH—C (＝ O) —O—) (urethane bond-containing compound). This makes it possible to further improve the etching resistance of the exposed portion and to realize a conductive layer having excellent flexibility and elasticity. Therefore, the adhesion between the base material and the conductive layer can be improved, and occurrence of problems such as peeling and disconnection can be suppressed at a higher level. Preferable examples of the urethane bond-containing compound include urethane-modified (meth) acrylate and urethane-modified epoxy. The proportion of the urethane bond-containing compound in the entire photopolymerizable compound is more preferably about 30% by mass or more, typically 50% by mass or more, for example, 95% by mass or more, substantially 100% by mass. % By mass.

  Although not particularly limited, the weight-average molecular weight of the photopolymerizable compound may be generally about 100 to 10,000, typically 200 to 5,000, for example, 300 to 2,000. In the present specification, the “weight average molecular weight” refers to a weight-based average molecular weight measured by gel chromatography (Gel Permeation Chromatography: GPC) and converted using a standard polystyrene calibration curve. When the photopolymerizable compound is a monomer, it has the same meaning as the molecular weight.

  Although not particularly limited, the proportion of the photopolymerizable compound in the entire photosensitive composition is generally 0.1 to 20% by mass, typically 0.5 to 10% by mass, for example, 2 to 8% by mass. %, More preferably 3 to 6% by mass. By satisfying the above range, the photocurability of the photosensitive composition is sufficiently exhibited, and a conductive layer can be stably formed at a higher level.

<Photopolymerization initiator>
The photopolymerization initiator is a component that is decomposed by irradiation with light energy such as ultraviolet rays, generates active species such as radicals and cations, and starts the polymerization reaction of the photopolymerizable compound. In the photosensitive composition disclosed herein, the photopolymerization initiator comprises at least two kinds of components: (1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide; (2) α-aminoalkyl Phenones; as essential components.

  The photopolymerization initiators (1) and (2) have different absorption wavelengths. Therefore, when these are used in combination, the absorption wavelength region is broadened and active species can be generated with high efficiency as compared with the case where one type of photopolymerization initiator is used alone. Further, due to the synergistic effect of the photopolymerization initiators (1) and (2), a longer development margin time is secured in the development process, for example, the time to the break point (BP) remains unchanged. can do. In combination with the above-described effects, the technology disclosed herein can improve the fine line forming property and form a fine line with a line width of 30 μm or less with good reproducibility. Hereinafter, the photopolymerization initiators (1) and (2) will be described.

(1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide is a monoacylphosphine oxide (MAPO). Examples of commercially available products include DAROCUR (trademark) TPO and IRGACURE (trademark) TPO (both are manufactured by BASF Japan Ltd.). Acylphosphine oxide-based photopolymerization initiators have excellent compatibility with photopolymerizable compounds and organic dispersion media. Therefore, it is effective for improving the storage stability of the photosensitive composition.

  In addition, bisacylphosphine oxide (BAPO), for example, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide is used as a photopolymerization initiator classified into the same acylphosphine oxide system as the above (1). Is mentioned. However, when a bisacylphosphine oxide is used instead of the above (1), as shown in the test examples described below, the above-described effects of the technology disclosed herein are not exhibited. That is, it can be said that the combined use of the photopolymerization initiators (1) and (2) has specificity.

  In the technology disclosed herein, the above (1) is a main component of the photopolymerization initiator. In other words, when the total amount of the photopolymerization initiator is 100% by mass, the ratio of the above (1) accounts for 50% by mass or more. As a result, fine line forming properties can be improved, and a fine line can be suitably formed. From such a viewpoint, the ratio of the above (1) may be, for example, 75% by mass or more, preferably 80% by mass or more, more preferably 85% by mass or more. In addition, from the viewpoint of better exhibiting the synergistic effect with the above (2) and improving the adhesion between the base material and the conductive layer, the ratio of the above (1) is approximately 90% by mass or less, preferably. It may be 85% by mass or less.

(2) As the α-aminoalkylphenones, any compound having an α-aminoalkylphenone skeleton may be used, and one or more conventionally known compounds may be appropriately selected and used. The α-aminoalkylphenone skeleton can be grasped, for example, as a functional group having an intramolecular cleavage type photopolymerization initiation ability. The alkyl moiety may be linear or branched. The alkyl moiety may have a substituent. Preferred examples of the α-aminoalkylphenones include compounds having a molecular weight of about 1000 or less, typically 200 to 500, for example, 250 to 400. Another preferred example is a compound having an α-aminoacetophenone skeleton. As a preferred example of the compound having an α-aminoacetophenone skeleton, a compound having the following structural portion (A) is given.

In the above (A), R ¹ and R ² are each independently selected from a hydrocarbon group having 1 to 18 carbon atoms. R ¹ and R ² may be the same or different. R ¹ is, for example, an alkyl group having 1 to 18 carbon atoms. The number of carbon atoms in R ¹ is preferably 1 to 8, typically 1 to 4, for example 1, 2 or 3. R ² is, for example, an alkyl group having 1 to 18 carbon atoms, an aryl group or an arylalkyl group. R ² preferably has 1 to 8 carbon atoms. Further, R ³ and R ⁴ are each independently selected from a hydrogen atom or a hydrocarbon group having 1 to 18 carbon atoms. R ³ and R ⁴ may be the same or different. R ³ and R ⁴ are, for example, each independently an alkyl group having 1 to 18 carbon atoms, an aryl group, an arylalkyl group, or a cyclic alkyl ether group in which R ³ and R ⁴ are bonded. The total number of carbon atoms of R ³ and ^{R 4} is preferably 1-8, typically 1-6, such as 2-4.

  As a specific example of the above (2), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1,2- (dimethylamino) -2-[(4-methylphenyl) methyl]- 1- [4- (4-morpholinyl) phenyl] -1-butanone, 2-methyl-1- [4- (methylthio) phenyl] -2-monophorinopropan-1-one, N, N-dimethylaminoacetophenone And the like. Examples of commercially available products include IRGACURE (trademark) 369, IRGACURE (trademark) 379, and IRGACURE (trademark) 907 (all manufactured by BASF Japan Ltd.).

  Although not particularly limited, from the viewpoint of exhibiting the effect of the technology disclosed herein at a high level, when the total amount of the photopolymerization initiator is 100% by mass, the ratio of the above (2) is: It may be about 10% by mass or more. Further, from the viewpoint of improving the adhesion between the base material and the conductive layer, the ratio of the above (2) may be 15% by mass or more. In addition, from the viewpoint of further improving the fine line forming property, the ratio of the above (2) may be, for example, 25% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less.

  Although not particularly limited, from the viewpoint of exhibiting the effects of the technology disclosed herein at a high level, when the total amount of the photopolymerization initiator is 100% by mass, the above (1) and (2) Is about 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, for example, 100% by mass.

  Although not particularly limited, the mass ratio of the above (1) and (2) is preferably approximately 50:50 to 95: 5. As a result, the fine line formability can be improved, and the effects of the technology disclosed herein can be exhibited at a higher level. For example, even a conductive layer having a finer line can be formed with high accuracy. Further, from the viewpoint of further improving the etching resistance of the exposed portion and suppressing the peeling of the conductive layer, the mass ratio of the above (1) and (2) is preferably 50:50 to 90:10. Preferably, the ratio is 50:50 to 85:15.

  Although not particularly limited, the proportion of the photopolymerization initiator in the entire photosensitive composition is generally at least 0.01% by mass, typically at least 0.04% by mass, for example, at least 0.05% by mass. It is good. Thereby, the photocurability of the photosensitive composition is sufficiently exhibited, and the conductive layer can be stably formed. The proportion of the photopolymerization initiator in the whole photosensitive composition is generally 0.5% by mass or less, typically 0.3% by mass or less, preferably 0.2% by mass or less, for example, 0.1% by mass. % Or less. Thus, in the developing step, the opposite etching resistance and peeling property can be balanced at a higher level. Therefore, a longer development margin time can be ensured, and the fine line formability can be further improved.

  Although not particularly limited, the content ratio of the photopolymerization initiator is generally 0.01 to 1 part by mass, typically 0.02 to 0.2 part by mass, per 100 parts by mass of the conductive powder. For example, it may be 0.05 to 0.1 part by mass. The content ratio of the photopolymerization initiator is generally 0.1 to 25 parts by mass, typically 0.2 to 5 parts by mass, for example, 0.5 to 3 parts by mass, based on 100 parts by mass of the photopolymerizable compound. Parts, or even 1 to 2 parts by mass.

<Organic binder>
The photosensitive composition may contain an organic binder in addition to the essential components described above. The organic binder is a component that enhances the adhesiveness between the base material and the uncured conductive film. As the organic binder, one or more types can be appropriately selected from conventionally known ones according to, for example, the type of the base material, the type of the photopolymerizable compound, the type of the photopolymerization initiator, and the like. The organic binder is preferably one that can be easily removed with an etchant in the developing step. For example, when an alkaline etching solution is used in the developing step, a hydroxyl group (—OH), a carboxyl group (—C (＝ O) OH), an ester bond (—C (＝ O) O—), a sulfo group of _(-SO 3 H) or the like, a compound having a structural part showing acidity are preferable. This makes it difficult for residues to remain in unexposed portions, and for example, a space between fine lines can be stably secured.

  Preferred examples of the organic binder include cellulosic polymers such as methylcellulose, ethylcellulose, carboxymethylcellulose, and hydroxymethylcellulose, acrylic resins, phenolic resins, alkyd resins, polyvinyl alcohol, and polyvinyl butyral. Among them, a hydrophilic organic binder, for example, a cellulosic polymer or an acrylic resin is preferable from the viewpoint of easy removal in the developing step.

  When the photosensitive composition contains an organic binder, the ratio of the organic binder in the whole photosensitive composition is not particularly limited, but is generally 0.1 to 20% by mass, typically 0.5 to 20% by mass. It may be 10% by weight, for example 1 to 5% by weight. Although not particularly limited, the content ratios of the photopolymerizable compound and the organic binder are substantially equal (the difference between the two content ratios is approximately 1% by mass or less, for example, 0.5% by mass or less). Good. Thus, in the developing step, the opposite etching resistance (adhesion) and releasability can be balanced at a higher level.

<Organic dispersion medium>
The photosensitive composition may contain, in addition to the essential components described above, an organic dispersion medium for dispersing these components. The organic dispersion medium is a component that imparts appropriate viscosity and fluidity to the photosensitive composition, improves the handleability of the photosensitive composition, and improves the workability when forming a conductive film. is there. As the organic dispersion medium, one or more kinds can be appropriately selected from conventionally known ones according to, for example, the type of the photopolymerizable compound and the photopolymerization initiator.

  Preferable examples of the organic dispersion medium include alcohol solvents such as terpineol, dihydroterpineol (mentanol), texanol, 3-methyl-3-methoxybutanol, and benzyl alcohol; glycol solvents such as ethylene glycol, propylene glycol, and diethylene glycol; Ether solvents such as dipropylene glycol methyl ether, methyl cellosolve (ethylene glycol monomethyl ether), cellosolve (ethylene glycol monoethyl ether), butyl carbitol (diethylene glycol monobutyl ether); diethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate; Butyl glycol acetate, butyl diglycol acetate, butyl cellosolve acetate And ester solvents such as butyl carbitol acetate (diethylene glycol monobutyl ether acetate) and isobornyl acetate; hydrocarbon solvents such as toluene, xylene, naphtha and petroleum hydrocarbons; and organic solvents such as mineral spirits. Can be

  Among them, an organic solvent having a boiling point of 150 ° C. or more, and more preferably an organic solvent having a boiling point of 170 ° C. or more, is preferable from the viewpoint of improving the storage stability of the photosensitive composition and the ease of handling during formation of the conductive film. As another preferred example, an organic solvent having a boiling point of 250 ° C. or lower, and more preferably an organic solvent having a boiling point of 220 ° C. or lower, is preferable from the viewpoint of suppressing the drying temperature after printing the conductive film. Thereby, productivity can be improved and production cost can be reduced.

  Further, for example, in a use of manufacturing a ceramic electronic component by forming a conductive layer on a ceramic base material, an organic solvent having low permeability to a ceramic green sheet is preferable. Examples of the organic solvent having low permeability to the ceramic green sheet include an organic solvent having a three-dimensionally bulky structure, such as a cyclohexyl group and a tert-butyl group, and an organic solvent having a relatively large molecular weight. Further, for example, an organic solvent having low permeability to the ceramic green sheet as described above and an organic solvent capable of suitably dissolving components (eg, a photopolymerizable substance and / or a photopolymerization initiator) contained in the photosensitive composition. It is also preferable to mix a solvent with an arbitrary ratio and use it as an organic dispersion medium.

  Examples of commercially available organic solvents having the above-mentioned properties (boiling point and permeability into ceramic green sheets) include, for example, Dwanol DPM (trademark) (boiling point: 190 ° C., manufactured by Dow Chemical Company) and Dwanol DPMA (trademark) ) (Boiling point: 209 ° C, manufactured by Dow Chemical Company), mentanol (boiling point: 207 ° C), mentanol P (boiling point: 216 ° C), Isopar H (boiling point: 176 ° C, manufactured by Kanto Fuel Co., Ltd.), SW-1800 (Boiling point: 198 ° C., manufactured by Maruzen Oil Co., Ltd.).

  When the photosensitive composition contains an organic dispersion medium, the ratio of the organic dispersion medium in the entire photosensitive composition is not particularly limited, but is generally about 1 to 50% by mass, typically 3 to 50% by mass. It may be 30% by mass, for example 5 to 20% by mass.

<Other ingredients>
The photosensitive composition may further contain, if necessary, various additional components in addition to the components described above, as long as the effects of the technology disclosed herein are not significantly impaired. As the additive component, one or more conventionally known components can be appropriately selected and used. Examples of the additional components include, for example, an inorganic filler, a photosensitizer, a polymerization inhibitor, a radical scavenger, an antioxidant, an ultraviolet absorber, a plasticizer, a surfactant, a leveling agent, a thickener, a dispersant, Examples include an antifoaming agent, a gelling inhibitor, a stabilizer, a preservative, and a pigment. Although not particularly limited, the proportion of the additive component in the entire photosensitive composition is preferably approximately 5% by mass or less, for example, 3% by mass or less.

  As described above, the photosensitive composition disclosed herein contains both of the above two components (1) and (2) as a photopolymerization initiator. When the total amount of the photopolymerization initiator is 100% by mass, the ratio of the above (1) accounts for 50% by mass or more. Thereby, in the developing step, the etching resistance (adhesion) and the releasability can be balanced at a higher level. That is, the etching resistance of the exposed portion can be improved, and a longer development margin time can be secured. As a result, the exposed portion can be appropriately fixed on the substrate after the development step, and occurrence of problems such as peeling and disconnection can be suppressed. In addition, it is possible to improve the peelability of the conductive film, appropriately remove unexposed portions, and suppress the exposed portions from becoming too thick. In other words, it is possible to improve the fine line formability of the exposed portion. As a result, a space can be stably secured between the adjacent wirings, and occurrence of a short circuit can be suppressed. In addition, according to the technology disclosed herein, these effects can be combined to form a fine line with a line width of 30 μm or less with good reproducibility. Further, the yield can be improved.

<Uses of photosensitive composition>
According to the photosensitive composition disclosed herein, fine lines with a line width finer than 30 μm can be stably formed with high resolution. In addition, peeling of the conductive layer, disconnection, and the like can be reduced, and occurrence of a short circuit can be suppressed. Therefore, the photosensitive composition disclosed herein can be suitably used for forming a conductive layer in various electronic components such as an inductance component, a capacitor component, and a multilayer circuit board.

  The electronic component may be of various mounting forms such as a surface mounting type and a through-hole mounting type. The electronic component may be a laminated type, a wound type, or a thin film type. Typical examples of the inductance component include a high-frequency filter, a common mode filter, an inductor (coil) for a high-frequency circuit, an inductor (coil) for a general circuit, a high-frequency filter, a choke coil, and a transformer.

  The photosensitive composition in which the conductive powder contains metal-ceramic core-shell particles can be suitably used for forming a conductive layer of a ceramic electronic component. In this specification, the term “ceramic electronic component” includes all electronic components having an amorphous ceramic base (glass ceramic base) or a crystalline (ie, non-glass) ceramic base. Typical examples are a high-frequency filter having a ceramic substrate, a ceramic inductor (coil), a ceramic capacitor, a low-temperature co-fired ceramics substrate (LTCC substrate), and a high-temperature co-fired multilayer ceramic substrate (LTC substrate). Co-fired Ceramics Substrate: HTCC substrate) and the like.

  FIG. 1 is a cross-sectional view schematically showing the structure of the multilayer chip inductor 1. Note that the dimensional relationships (length, width, thickness, etc.) in FIG. 1 do not necessarily reflect actual dimensional relationships. Reference signs X and Y in the drawings represent a left-right direction and a vertical direction, respectively. However, this is only for convenience of explanation.

  The multilayer chip inductor 1 includes a main body 10 and external electrodes 20 provided on both side surfaces of the main body 10 in the left-right direction X. The multilayer chip inductor 1 has a size of, for example, a 1608 shape (1.6 mm × 0.8 mm), a 2520 shape (2.5 mm × 2.0 mm), or the like.

  The main body 10 has a structure in which a ceramic layer (dielectric layer) 12 and an internal electrode layer 14 are integrated. The ceramic layer 12 is made of, for example, the above-described ceramic material as a material capable of forming a coating portion of the conductive powder. The internal electrode layers 14 are arranged between the ceramic layers 12 in the vertical direction Y. The internal electrode layer 14 is formed using the above-described photosensitive composition. The internal electrode layers 14 adjacent to each other in the vertical direction Y with the ceramic layer 12 interposed therebetween are electrically connected through vias 16 provided in the ceramic layer 12. Thus, the internal electrode layer 14 is formed in a three-dimensional spiral shape (spiral shape). Both ends of the internal electrode layer 14 are connected to the external electrodes 20, respectively.

Such a multilayer chip inductor 1 can be manufactured, for example, by the following procedure.
That is, first, a paste containing a ceramic material as a raw material, a binder resin, and an organic solvent is prepared and supplied onto a carrier sheet to form a ceramic green sheet. Next, after rolling the ceramic green sheet, it is cut into a desired size to obtain a plurality of green sheets for forming a ceramic layer. Next, via holes are appropriately formed at predetermined positions of the plurality of green sheets for forming a ceramic layer using a punch or the like.

  Next, using the above-described photosensitive composition, a conductive film having a predetermined coil pattern is formed at predetermined positions of the plurality of green sheets for forming a ceramic layer. As an example, the following steps: (Step S1: Step of forming a film) A conductive film formed of a dried photosensitive composition is applied by drying the photosensitive composition on a green sheet for forming a ceramic layer. (Step S2: exposure step) A step of covering the conductive film with a photomask having a predetermined opening pattern, exposing through the photomask, and partially photocuring the conductive film; (Step S3: developing Step) A step of etching the photo-cured conductive film to remove an unexposed portion, whereby a non-fired conductive film can be formed.

  In forming a conductive film using the photosensitive composition, a conventionally known method can be appropriately used. For example, in (Step S1), the application of the photosensitive composition can be performed using various printing methods such as screen printing, a bar coater, or the like. The drying of the photosensitive composition may be performed at a temperature equal to or lower than the boiling point of the photopolymerizable compound and the photopolymerization initiator, typically 50 to 100 ° C. In (Step S2), for the exposure, for example, an exposure machine that emits light in a wavelength range of 10 to 500 nm, for example, an ultraviolet irradiation lamp such as a high-pressure mercury lamp, a metal halide lamp, or a xenon lamp can be used. In (Step S3), typically, an alkaline etchant can be used for the etching. For example, an aqueous solution containing sodium hydroxide, sodium carbonate, or the like can be used. The concentration of the alkaline aqueous solution may be adjusted to, for example, 0.01 to 0.5% by mass.

Next, (Step S4: firing step) A plurality of green sheets for forming a ceramic layer on which the unfired conductive film is formed are laminated and pressed. Thus, a laminate of unfired ceramic green sheets is produced. Next, the laminate of ceramic green sheets is fired at, for example, 600 to 1000C. As a result, the ceramic green sheets are integrally sintered, and the main body 10 including the ceramic layer 12 and the internal electrode layer 14 made of the fired body of the photosensitive composition is formed. Then, an appropriate external electrode forming paste is applied to both end portions of the main body 10 and the external electrode 20 is formed by firing.
As described above, the multilayer chip inductor 1 can be manufactured.

  Hereinafter, some embodiments of the present invention will be described, but it is not intended to limit the present invention to those shown in the embodiments.

(Preparation of silver powder)
First, it was prepared a commercially available two types of silver powders having different D ₅₀ particle size (silver powder a, b). Incidentally, the silver powder a _is a _{D 50} particle size is 3.9 .mu.m, silver powder b _{is D 50} particle size is 2.8 .mu.m. The silver powders a and b both have a lightness L ^* of 50 to 80 in the L ^* a ^* b ^* color system based on JIS Z 8781: 2013.

Further, silver powder c was prepared using silver powder a. Specifically, first, zirconium butoxide was added to methanol to prepare a coating solution. Next, silver powder a was added to the coating solution and stirred for 1 hour. Next, a solid content was recovered from the coating solution and dried at 100 ° C. As a result, silver powder (silver-zirconia core-shell particles) surface-coated with zirconium butoxide in an amount of 0.5 parts by mass in terms of zirconium oxide (ZrO ₂ ) based on 100 parts by mass of the silver powder was obtained. Thus, silver powder c was prepared.

(Preparation of photopolymerization initiator)
Next, four types of commercially available photopolymerization initiators (initiators a to d) shown below were prepared. The initiators a and b are α-aminoalkylphenone-based photopolymerization initiators, and the initiators c and d are acylphosphine oxide-based photopolymerization initiators.
-Initiator a: 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone-1
-Initiator b: 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone-Initiator c: 2,4,6 -Trimethylbenzoyl-diphenyl-phosphine oxide initiator d: bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide

(Preparation of photosensitive composition)
First, a urethane acrylate monomer as a photopolymerizable compound, an organic binder, and the above photopolymerization initiator were weighed so as to have a content shown in Table 1, and dissolved in an organic dispersion medium to prepare a vehicle. did. Then, the photosensitive compositions (Examples 1 to 7 and Comparative Examples 1 to 6) were prepared by mixing the prepared silver powder and the prepared vehicle at a mass ratio of 77:23. The mass ratios shown in Table 1 are based on 100% by mass of the entire photosensitive composition. When the total mass ratio shown in Table 1 is less than 100% by mass, other additive components are used. (E.g., a polymerization inhibitor, a sensitizer, a gelling inhibitor, an ultraviolet absorber).

(Preparation of wiring pattern)
First, using a stainless steel screen, the photosensitive composition prepared above was applied onto a commercially available ceramic green sheet. Next, it was dried at 60 ° C. for 15 minutes to form a conductive film on the green sheet (film forming step). Next, a photomask was placed over the conductive film. At this time, a spiral pattern having a line width of wiring of 25 μm and a space (space) between adjacent lines of 25 μm (L / S = 25 μm / 25 μm) was used as the photomask. With this photomask covered, light was irradiated at an intensity of 2500 mJ / cm ² by an exposure machine to cure the exposed portion (exposure step). After the exposure, a 0.1% by mass aqueous solution of alkaline Na ₂ CO ₃ was sprayed on the surface of the ceramic green green sheet until the break point (BP) was reached (development step). Here, B. P. The time was defined as the time until the unexposed portion was developed with 0.1% by mass of an alkaline etching solution and it could be visually confirmed that the unexposed portion had disappeared. After removing the unexposed portions in this way, the substrate was washed with pure water and dried at room temperature. This was fired at 700 ° C. (firing step). Thus, a conductive layer of a wiring pattern in which spiral wirings were arranged was formed on the ceramic green sheet.

(Evaluation of wiring pattern)
The peeling, the line width, and the development margin of the wiring pattern prepared above were evaluated, and a comprehensive evaluation was performed based on these evaluations.

・ Evaluation of peeling:
The wiring pattern was observed with an electron microscope, and the peeling was evaluated. The observation image was taken at a magnification of 200 times. Then, the presence or absence of peeling and disconnection was confirmed from the obtained observation image. The results are shown in the column of "Evaluation of peeling" in Table 1. The notation in this column is as follows.
"○": No peeling "△": Partial peeling (no disconnection)
"X": Peeling, disconnection

・ Evaluation of line width:
The line width of the wiring pattern was measured from the observation image. The measurement of the line width was performed for a plurality of visual fields, and the arithmetic average value was defined as the line width (μm). The results are shown in the column of “line width” in Table 1. The notations in the evaluation column are as follows.
“O”: 20 to 30 μm (within target value)
“×”: 30 μm or more FIG. 2 shows the relationship between the content ratio of the initiator c and the line width of the wiring pattern for the evaluation results of Comparative Examples 1 to 3 and Examples 1 to 4.

・ Evaluation of development margin:
In the above exposure step, an alkaline etching solution was sprayed for 10 seconds (BP + 10 seconds) beyond the break point. Then, the conductive film after the exposure step was observed with an electron microscope in the same manner as described above, and a development margin was evaluated from the obtained observation image. The results are shown in the column of "Evaluation of development margin" in Table 1. The notation in this column is as follows.
“O”: The shape of the conductive film is maintained “X”: The shape of the conductive film is not maintained

·Comprehensive evaluation:
“○”: In each of the above-described evaluations of peeling, line width, and development margin, none of Δ and X was found (all are Δ).
“△”: In each of the above-described evaluations of peeling, line width, and development margin, there is one Δ and the rest are Δ. “×”: In each of the above-described evaluations of peeling, line width, and development margin, X is 1 More than one

Comparative Examples 1 and 2 are test examples using only initiator a. As shown in Table 1, in Comparative Example 1, although the developing margin was secured for 10 seconds or more, the line width of the conductive pattern was largely varied, and the line width was thickened in some places. As a result, the line width became too large than the target value, and it was difficult to form a stable fine line. In Comparative Example 2 in which the content of the initiator a was smaller than that in Comparative Example 1, a sufficient development margin could not be secured.
Comparative Example 4 is a test example using only initiator c. As shown in Table 1, in Comparative Example 4, peeling or disconnection was observed in the conductive pattern, and it was difficult to form a fine line itself.

  Comparative Example 3, Examples 1 to 4 are test examples in which initiators a and c were used in combination. As shown in Table 1 and FIG. 2, in Comparative Example 3 in which the content of the initiator c was small, the effect of the addition of the initiator c was not sufficiently exhibited, and as in Comparative Example 1, a stable fine line was formed. Was difficult. On the other hand, in Examples 1 to 4 in which the content of the initiator c was 50% by mass or more of the entire photopolymerization initiator, a sufficient development margin was secured and a fine line having a desired line width was stable. Was formed. Further, by increasing the content of the initiator c, the fine line forming property was further improved. In particular, in Examples 1 to 3 in which the mass ratio of the initiator c: the initiator a was 50:50 to 85:15, the etching resistance of the exposed portion was improved, and the peeling of the conductive layer was better suppressed. .

  Example 5 is a test example using the same α-aminoalkylphenones as initiator b instead of initiator a. As shown in Table 1, in Example 5, as in Examples 1 to 4, a sufficient development margin was secured, and a stable fine line was formed. In other words, even when the initiator b is used instead of the initiator a, the effect of the technology disclosed herein has been exhibited.

  Comparative Examples 5 and 6 are test examples in which the same acylphosphine oxide-based initiator d was used instead of the initiator c. As shown in Table 1, in Comparative Examples 5 and 6, unlike Examples 1 to 4, the development margin was insufficient and / or it was difficult to form a stable fine line. In other words, when the initiator d was used instead of the initiator c, the effect of the technology disclosed herein was not exhibited.

  Examples 6 and 7 are test examples using silver powder c instead of silver powders a and b. As shown in Table 1, in Examples 6 and 7, similarly to Examples 1 to 4, a sufficient development margin was secured, and stable fine line formation was realized. Furthermore, the effects of the technology disclosed herein were exhibited at a higher level than in the case where silver powders a and b were used, and the fine line forming property was further improved.

From the above results, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (initiator c) and α-aminoalkylphenones (initiators a and b) were used in combination as photopolymerization initiators. In addition, by containing 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide in a proportion of 50% by mass or more of the entire photopolymerization initiator, a longer development margin time can be secured in the development step. In addition to this, it is possible to improve the fine line forming property of the exposed portion. As a result, a fine line having a line width of 30 μm or less can be formed with good reproducibility. In addition, it has been found that the occurrence of defects such as short-circuit failure, peeling, and disconnection can be suppressed, and the yield can be improved.
These results show the significance of the technology disclosed herein.

  As described above, the present invention has been described in detail, but these are merely examples, and the present invention can be variously modified without departing from the gist thereof.

DESCRIPTION OF SYMBOLS 1 Multilayer chip inductor 10 Main part 12 Ceramic layer 14 Internal electrode layer 20 External electrode

Claims (12)

A photosensitive composition used for producing a conductive layer including a wiring having a line width of 30 μm or less,
Including a conductive powder, a photopolymerizable compound, a photopolymerization initiator, and an organic binder (excluding an organic binder having a photoreactive (meth) acryloyl group in a molecule) ,
The photopolymerization initiator,
At least two components:
(1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide;
(2) α-aminoalkylphenones;
Wherein the (1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide accounts for 50% by mass or more when the entire photopolymerization initiator is 100% by mass. object. The mass ratio of the (1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide to the (2) α-aminoacetophenones is 50:50 to 90:10,
The photosensitive composition according to claim 1. The mass ratio of the (1) 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide to the (2) α-aminoacetophenone is 50:50 to 85:15,
The photosensitive composition according to claim 1. When the entire photosensitive composition is 100% by mass, the proportion of the photopolymerization initiator is 2% by mass or less.
The photosensitive composition according to claim 1. The photopolymerizable compound includes a photopolymerizable compound having a urethane bond,
The photosensitive composition according to claim 1. The conductive powder contains silver-based particles,
The photosensitive composition according to claim 1. The conductive powder includes a core portion including a metal material, and at least a part of a surface of the core portion, and a coating portion including a ceramic material.
The photosensitive composition according to claim 1. In the L ^* a ^* b ^* color system based on JIS Z 8781: 2013, the brightness L ^* of the conductive powder is 50 or more;
The photosensitive composition according to claim 1. The organic solvent further having a boiling point of 150 ° C. or more and 250 ° C. or less,
The photosensitive composition according to claim 1. Green sheet,
A conductive film comprising a dried body of the photosensitive composition according to any one of claims 1 to 9, which is disposed on the green sheet,
A composite comprising:   An electronic component comprising a conductive layer formed of the fired body of the photosensitive composition according to claim 1. The photosensitive composition according to any one of claims 1 to 9 is applied to a substrate, exposed and developed, and then fired to form a conductive layer made of a fired body of the photosensitive composition. A method for manufacturing an electronic component, comprising:

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