JP6646643B2 - Photosensitive composition and its use - Google Patents

Description

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

  In the production of electronic components such as inductors, there is known a method of using a photosensitive composition containing a conductive powder and a photosensitive organic component to form a conductive layer by a so-called photolithography method (for example, Patent Document 1). -5). In such a method, first, a photosensitive composition is applied onto a base material by a printing method or the like as in the related art, and dried to form a film. Next, a photomask having a predetermined opening pattern is placed on the formed film, and the film is exposed through the photomask. Thus, the exposed film-shaped portion is light-cured. Next, the uncured film-shaped body portion which has been shielded from light by the photomask is removed by etching and cleaning with an etchant. Then, by firing this, a conductive layer patterned into a desired shape is formed (baked). According to such a method, a conductive layer having a finer pattern can be formed as compared with the case where various conventional printing methods are used.

Patent No. 5163687 WO 2015/122345 pamphlet JP 2016-138310 A Patent No. 5352768 JP 2006-193795 A

  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 fine-line conductive layer in which the width (line width) of the wiring forming the conductive layer is 30 μm or less, and further 20 μm or less.

  However, according to the study of the present inventors, it has been difficult to form a conductive layer with high resolution when using a photosensitive composition as described in the above-mentioned patent document. As an example, it has been difficult to stably form a thin line-shaped wiring because the line width is increased. Further, as another example, when a wiring pattern is formed, as shown in the schematic diagram of FIG. 2, a residue that cannot be completely removed by etching in a space (space) between adjacent wirings (hereinafter, referred to as a “line-to-line Residues "). As a result, a leakage current may occur due to a tunnel effect, or a short circuit may occur due to connection between wirings.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a photosensitive composition capable of forming a fine-line conductive layer with little interline residue at a high resolution. 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 comprising a conductive powder and a photosensitive organic component. The conductive powder is a D ₅₀ particle size based on volume based on the laser diffraction scattering method is 1μm or 5μm or less, the following two types: (1) the amount of organic component based on thermogravimetric analysis 0.1 wt% (2) a second conductive powder having a benzotriazole-based compound adhered to its surface and having an organic component amount of at least 0.5% by mass based on thermogravimetric analysis; The sum of the components accounts for 90% by mass or more when the entirety of the conductive powder is 100% by mass.

  In the above photosensitive composition, the first conductive powder and the second conductive powder having different amounts of organic components are mixed in the conductive powder, and the total of the first conductive powder and the second conductive powder is conductive. It accounts for 90% by mass or more of the whole powder. As described above, by using the first conductive powder and the second conductive powder together, a fine-line conductive layer can be formed more stably than when, for example, these are used alone. In addition, since the second conductive powder contains the benzotriazole-based compound, a residue between lines is less likely to remain, and a space can be stably secured between wirings. Therefore, it is possible to reduce the leakage current and suppress the occurrence of the short-circuit failure. With the above effects, a conductive layer with high resolution can be formed.

  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 mass ratio between the first conductive powder and the second conductive powder is (first conductive powder: second conductive powder) = 85: 15 to 20:80. . As a result, the effects of the technology disclosed herein can be exerted 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 first conductive powder is a core-shell particle including a metal material serving as a core and a ceramic material covering at least a part of a surface of the core. Thereby, the stability of the conductive powder in the photosensitive composition can be further improved, and a highly durable conductive layer can be realized. Further, for example, in a case where a conductive layer is formed on a ceramic base material to manufacture a ceramic electronic component, the integration with the ceramic base material can be enhanced.

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. As a result, light can stably reach the deep portion of the uncured conductive film, and a thick conductive layer can be stably realized.

  In a preferred embodiment disclosed herein, the organic solvent 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, a fine-line conductive layer with little interline residue 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, a step of applying the photosensitive composition on a substrate, performing photocuring and etching treatment, and then baking to form a conductive layer made of a fired body of the photosensitive composition And a method for manufacturing an electronic component. According to such a manufacturing method, an electronic component having a small and / or high-density conductive layer can be suitably manufactured.

It is sectional drawing which shows typically the structure of the multilayer chip inductor which concerns on one Embodiment. It is a schematic diagram for demonstrating the residue between lines.

  Hereinafter, preferred embodiments of the present invention will be described. In addition, matters other than matters specifically referred to in the present specification (for example, conductive powder contained in the 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 film or a conductive layer, the method for manufacturing an electronic component, and the like) can be understood based on the technical content taught by the present specification and general technical 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, a film (dried product) obtained by drying the conductive composition at a temperature equal to or lower than the boiling point of the benzotriazole-based compound (approximately 200 ° C. or lower, for example, 100 ° C. or lower) is referred to as “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 conductive composition at a temperature equal to or higher than the sintering temperature of the conductive powder is referred to as “conductive layer”. The conductive layer includes a wiring (linear body), a wiring pattern, and a solid 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 contains a conductive powder and a photosensitive organic component 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. In the technology disclosed herein, the conductive powder is a mixed powder containing at least a first conductive powder and a second conductive powder. And the sum of the first conductive powder and the second conductive powder accounts for 90% by mass or more when the whole of the conductive powder is 100% by mass. As a result, a fine line conductive layer can be formed with high resolution.

  The conductive powder may be composed of the first conductive powder and the second conductive powder, or may include other conductive powder. From the viewpoint of exhibiting the effects of the technology disclosed herein at a higher level, the total of the first conductive powder and the second conductive powder is preferably 95% by mass or more of the entire conductive powder, More preferably, it is 98% by mass or more.

  The first conductive powder is a conductive powder in which the amount of the organic component is kept low. The organic component contained in the conductive powder is mainly derived from an organic surface coating agent adhering to the surface of the conductive powder and a residual organic component used for producing the conductive powder, for example, an organic solvent. The organic surface coating agent will be described later in detail in the section of the second conductive powder.

  In the technology disclosed herein, the first conductive powder has an organic component amount of 0.1% by mass or less. The first conductive powder is not particularly limited, except that the amount of the organic component is 0.1% by mass or less. By including the first conductive powder in which the amount of the organic component is suppressed as described above in the conductive powder, the etching resistance of the conductive film can be improved, and the cured conductive film portion can be appropriately formed after the etching process. On the substrate. Therefore, peeling of the conductive film and excessive thinning of the wiring can be suppressed. From the above viewpoint, the amount of the organic component of the first conductive powder may be, for example, 0.08% by mass or less.

  The first conductive powder may contain an organic component intentionally or unavoidably, and may not contain the organic component (may be lower than the detection lower limit). The amount of the organic component of the first conductive powder may be approximately 0.01% by mass or more, for example, 0.03% by mass or more. In other words, the first conductive powder may have an organic surface coating agent attached to the surface or may include a residual solvent. When the first conductive powder contains an organic surface coating, it is preferable that the first conductive powder contains the same type of organic surface coating as the second conductive powder. For example, it is preferable to include a benzotriazole-based compound.

  In addition, in this specification, "the amount of organic components" means the mass decay rate measured by the following measuring method. That is, first, a predetermined amount of conductive powder is weighed as a measurement sample, and this measurement sample is heated at room temperature at a rate of 10 ° C./min in an air atmosphere using a thermogravimeter (TG). Heat from (25 ° C) to 600 ° C. Then, the following equation: Organic component amount (%) = [(mass before heating) − (mass after heating to 600 ° C.)] / (Mass before heating) × 100; mass change before and after heating (mass attenuation) Rate). The mass decay rate determined in this way is called an organic component amount. The unit is mass%.

The second conductive powder is a conductive powder having a higher organic component amount than the first conductive powder.
In the technology disclosed herein, a benzotriazole-based compound is attached to the surface of the second conductive powder. Benzotriazole-based compounds are organic surface coating agents. The second conductive powder has an organic component amount of at least 0.5% by mass. The second conductive powder is not particularly limited, except that the benzotriazole-based compound is attached to the surface and the amount of the organic component is at least 0.5% by mass. By including such a second conductive powder in the conductive powder, it is possible to improve the peelability of the uncured portion at the time of the etching treatment and suppress the wiring from becoming too thick. In addition, the residue between lines hardly remains in the space between the wires, and a space can be stably secured between the wires. Therefore, it is possible to reduce the leakage current and suppress the occurrence of the short-circuit failure.

  From the above viewpoint, the amount of the organic component of the second conductive powder is preferably 0.7% by mass or more, more preferably 0.75% by mass or more, for example, 0.8% by mass or more. Is also good. Further, although not particularly limited, the upper limit of the amount of the organic component of the second conductive powder is approximately 2% by mass or less in view of the range of the amount of the organic component of the commercially available conductive powder. The upper limit of the amount of the organic component of the second conductive powder is preferably 1.5% by mass or less, and more preferably 1% by mass or less, from the viewpoint of densification and low resistance of the conductive layer.

  The benzotriazole-based compound adhering to the surface of the second conductive powder is an organic surface coating agent that improves the stability and storage stability of the conductive powder. The benzotriazole-based compound may be any compound having a benzotriazole skeleton. As a preferred example, a compound having one or two or more structural portions of 1H-benzotriazole of the following (1) may be mentioned.

  As specific examples of the benzotriazole-based compound, 1H-benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-butyl) Phenyl) benzotriazole, 2- (2′-hydroxy-4′-n-octoxyphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole, 2- (2′- (Hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole, 2-hydroxy-4- (2-hydroxy-3-methacryloxy) propoxybenzophenone, 2- (2′-hydroxy-3′-t-butyl) -5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-t-butyl-5 ' Methylphenyl) -5-chloro-benzotriazole, 2- (2'-hydroxy-3 ', 5'-di -t- butyl-phenyl) -5-chloro-benzotriazole, and the like. Among them, those containing no halogen element (for example, fluorine or chlorine) are preferable.

  Typically, the organic component contained in the second conductive powder mainly includes a benzotriazole-based compound (a component occupying 50 mol% or more in a molar ratio). The organic component of the second conductive powder is preferably a benzotriazole-based compound occupying 80 mol% or more, and more preferably a benzotriazole-based compound. It is known that the second conductive powder can be used as an organic surface coating agent in addition to the benzotriazole-based compound intentionally or inevitably, as long as the effect of the technology disclosed herein is not significantly impaired. May be further included. For example, when the total amount of the organic components of the second conductive powder is 100 mol%, in addition to the benzotriazole-based compound, another organic surface coating agent is generally less than 50 mol%, preferably 10 mol% or less. , More preferably 5 mol% or less. More preferably, the second conductive powder does not contain a fatty acid such as a carboxylic acid. As a result, the effects of the technology disclosed herein can be exerted at a higher level. The fact that the organic surface coating agent contains a benzotriazole-based compound can be confirmed by, for example, gas chromatography-mass spectrometry (GC-MS).

  Although not particularly limited, the mass ratio of the first conductive powder to the second conductive powder is approximately 95: 5 to 5:95, typically 90:10 to 10:90, preferably 85 : 15 to 20:80, more preferably 60:40 to 20:80, especially preferably 60:40 to 40:60. As a result, the effects of the technology disclosed herein can be exerted at a higher level. For example, even a conductive layer with a finer line can be formed with high resolution and high accuracy. In addition, by including the first conductive powder at a ratio equal to or higher than a predetermined value, the ratio of components that burn out during firing can be reduced, and a conductive layer having high density and low resistance can be suitably realized.

  The types of the first conductive powder and the second conductive powder are not particularly limited. As the first conductive powder and the second conductive powder, one or two or more types can be appropriately selected from conventionally known ones according to the application and the like. As a preferred example, gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), aluminum (Al), nickel (Ni), ruthenium (Ru), rhodium (Rh), Metals such as tungsten (W), iridium (Ir), and osmium (Os), as well as mixtures and alloys thereof, may be used. 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 aspect, the first conductive powder and / or the second conductive powder include silver-based particles. Silver is relatively inexpensive and has high electrical conductivity. For this reason, by including silver-based particles, a conductive layer having an excellent balance between cost and low resistance can be realized. The silver-based particles may be those containing a silver component. As an example, a simple substance of silver, the above-mentioned silver alloy, core-shell particles having silver-based particles as a core, and the like can be given.

  In another preferred aspect, the first conductive powder and / or the second conductive powder includes 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, and a highly durable conductive layer can be realized. Further, for example, by forming a conductive layer on a ceramic base material, in applications where ceramic electronic components are manufactured, by including metal-ceramic core-shell particles, it is possible to enhance the integration with the ceramic base material, Peeling or disconnection of the conductive layer after firing can be suitably suppressed.

  In particular, the first conductive powder having a small amount of the organic component preferably contains metal-ceramic core-shell particles, and more preferably the first conductive powder is formed of metal-ceramic core-shell particles. The first conductive powder having a small amount of the organic component tends to have relatively lower stability and storage stability in the conductive composition than the second conductive powder having a large amount of the organic component. When the first conductive powder contains the core-shell particles of metal-ceramic, the low organic component content can be compensated for, and the stability and storage stability of the whole conductive composition can be further improved.

  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, it is preferable that the first conductive powder and / or the second conductive powder include silver-ceramic core-shell particles.

  Although not particularly limited, examples of the ceramic material constituting the metal-ceramic coating portion include zirconium oxide (zirconia), magnesium oxide (magnesia), aluminum oxide (alumina), silicon oxide (silica), and oxide. Oxide materials such as titanium (titania), cerium oxide (ceria), yttrium oxide (yttria), and barium titanate; composite oxides such as cordierite, mullite, forsterite, steatite, sialon, zircon, and ferrite Materials; nitride materials such as silicon nitride (silicon nitride) and aluminum nitride (aluminum nitride); carbide materials such as silicon carbide (silicon carbide); hydroxide materials such as hydroxyapatite; . For example, for the purpose of manufacturing a ceramic electronic component by forming a conductive layer on a ceramic substrate, a ceramic material having the same or excellent affinity as the ceramic substrate is preferable.

  Although not particularly limited, the content ratio of the ceramic material may be, for example, 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the metal material of 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 an oxide It can be produced by reacting with a sol.

Conductive powder, the balance with exposure _{performance, D 50} particle size is 1 to 5 [mu] m. That is, the D ₅₀ particle size within the above range, to improve the exposure performance of the uncured conductive film, the conductive layer of the fine line can be stably formed. The first conductive powder and the second conductive powder, respectively, may D ₅₀ particle size is in the above range. Of from the viewpoint of improving the stability aggregating by suppressing conductive composition of the conductive powder, D ₅₀ particle size of the conductive powder is, for example, 1.5 [mu] m or more, may be 2.0μm or more. Fine line reduction and densification of the conductive layer, from the viewpoint of promoting a low resistance, D ₅₀ particle size of the conductive powder is, for example, 4.5 [mu] m or less, it may be not more than 4.0 .mu.m. 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%.

Although not particularly limited, the first conductive powder and the _{D 50} particle size of the second conductive powder, at least 0.5 [mu] m, typically 0.5 to 3.0 [mu] m, for example 1.0 It is preferable that the distance is about 2.0 μm. In other words, it is preferable that the particle size distribution of the entire conductive powder has multimodality. In an embodiment, _{D 50} particle size of the first conductive powder weight organic component is small, generally 3 to 5 [mu] m, for example in the range of 3.5～4.5Myuemu, weight organic component is large second conductive powder the _{D 50} particle size is generally 1～3.5Myuemu, for example it may be in the range of 1.5～3Myuemu. 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, to improve the denseness and filling properties of the conductive layer. As a result, the resistance of the conductive layer can be suitably reduced.

  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 first conductive powder and the second conductive powder each preferably have 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. As a result, the irradiation light can reach the deep portion of the uncured conductive film 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. Can be. From the above 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.

  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 having high density and high electric conductivity can be formed. Further, the handleability of the photosensitive composition and the workability in forming the conductive film can be improved.

<Photosensitive organic component>
The photosensitive organic component is a component that imparts photocurability to the conductive film. The photosensitive organic component is a component having a property of being cured by irradiation with light energy such as ultraviolet light. In the present specification, the “photosensitive organic component” refers to all photopolymerizable or photomodified organic compounds. As a preferred example, a mixture containing a photosensitive resin having an unsaturated bond and a photopolymerization initiator that generates an active species; a so-called diazo resin (for example, a condensate of aromatic bisazide and formaldehyde); an epoxy compound And a photoacid generator such as a diallyl iodonium salt; a naphthoquinonediazide compound; and the like. Among them, a mixture containing a photosensitive resin and a photopolymerization initiator is preferable from the viewpoint of stability and the like.

  The photosensitive resin is a component that is polymerized and cured by active species generated by the decomposition of the photopolymerization initiator. The photosensitive resin includes monomers, polymers, and oligomers having one or more unsaturated bonds. As the photosensitive resin, one or more kinds can be appropriately selected from conventionally known ones according to the use and the type of the base material. One preferred example is a radical polymerizable monomer having at least one radical polymerizable reactive group such as a (meth) acryloyl group or a vinyl group. Among them, a (meth) acrylate monomer having a (meth) acryloyl group is preferable from the viewpoint of suppressing the peeling of the conductive film. In this specification, “(meth) acryloyl” includes “methacryloyl” and “acryloyl”, and “(meth) acrylate” is a term including “methacrylate” and “acrylate”.

  (Meth) acrylate monomers include monofunctional (meth) acrylates having one functional group per molecule, polyfunctional (meth) acrylates having two or more functional groups per molecule, and modified products thereof. I do. Specific examples include polyfunctional (meth) acrylates such as pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate, and urethane (meth) acrylate having a urethane bond. Especially, it is preferable to contain urethane (meth) acrylate. Thereby, the stretchability and flexibility of the conductive film can be further improved, and the integration with the base material can be improved. The proportion of urethane (meth) acrylate in the entire photosensitive resin is preferably 30% by volume or more, for example, 50% by volume or more on a volume basis.

  The photopolymerization initiator is a component that is decomposed by light irradiation, generates active species such as radicals and cations, and starts the polymerization reaction of the photosensitive resin. As the photopolymerization initiator, one or more types can be appropriately selected from conventionally known ones according to the type of the photosensitive resin and the like. One preferred example is 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butane -1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4-diethylthioxanthone, benzophenone and the like.

  Although not particularly limited, the ratio of the photosensitive organic compound to the entire photosensitive composition is generally 0.1 to 25% by mass, typically 0.5 to 20% by mass, for example, 1 to 15% by mass. %. Further, the content ratio of the photosensitive resin may be, for example, 0.1 to 30 parts by mass with respect to 100 parts by mass of the conductive powder. Further, the content ratio of the photopolymerization initiator may be approximately 0.001 to 100 parts by mass, for example, 0.01 to 10 parts by mass with respect to 100 parts by mass of the photosensitive resin.

<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 to improve the handling properties of the photosensitive composition and the workability when forming a conductive film. As the organic dispersion medium, one or more kinds can be appropriately selected from conventionally known ones according to the kind of the photosensitive organic compound and the like. Preferred examples include terpineol, dihydroterpineol (menthol), alcohol solvents such as texanol, 3-methyl-3-methoxybutanol, and benzyl alcohol; glycol solvents such as ethylene glycol, propylene glycol, and diethylene glycol; dipropylene glycol methyl ether Ether solvents such as methylcellosolve (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, butyl carbonate Bi Tall acetate (diethylene glycol monobutyl ether acetate), ester solvents such as isobornyl acetate; mineral spirits; toluene, xylene, naphtha, hydrocarbon solvents such as petroleum hydrocarbon organic solvent and the like.

  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, for an application in which a conductive layer is formed on a ceramic base material to manufacture a ceramic electronic component, 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 a component (for example, a photosensitive organic component) contained in the photosensitive composition are mixed at an arbitrary ratio. And then used as an organic dispersion medium.

  Examples of the organic solvent having the above-mentioned properties (boiling point and permeability into the ceramic green sheet) include, for example, Dwanol DPM (trademark) (boiling point: 190 ° C., manufactured by Dow Chemical Company) and Dwanol DPMA (trademark) ( Boiling point: 209 ° C, 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.

<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 adhesion between the uncured conductive film and the substrate. As the organic binder, one or two or more types can be appropriately selected from conventionally known ones according to the type of the photosensitive organic compound and the base material and the like. Preferred examples include cellulosic polymers such as methylcellulose, ethylcellulose, carboxymethylcellulose, and hydroxymethylcellulose, acrylic resins, phenolic resins, alkyd resins, polyvinyl alcohol, and polyvinyl butyral. Above all, a hydrophilic organic binder such as a cellulosic polymer or an acrylic resin is preferable from the viewpoint of easy removal by etching.

<Other ingredients>
As long as the effects of the technology disclosed herein are not significantly impaired, the photosensitive composition may further contain various additional components as necessary in addition to the above-described essential components. As the additive component, one or more of 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, an anti-gelling agent, a stabilizer, an antioxidant, 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.

<Uses of photosensitive composition>
According to the photosensitive composition disclosed herein, a fine-line conductive layer having a small amount of residue between lines and having a line width finer than 30 μm, for example, and further having a line width finer than 20 μm can be formed with a high level. It can be formed stably at a resolution. In addition, peeling, disconnection, and the like of the conductive layer can be reduced. Further, it is possible to reduce the leakage current and to suppress the occurrence of the short-circuit failure. 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 (LTCC substrate). High Temperature Co-fired Ceramics Substrate: HTCC substrate).

  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 shape of the multilayer chip inductor 1 is, for example, 1608 (1.6 mm × 0.8 mm), 2520 (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) a step of applying a photosensitive composition onto a green sheet for forming a ceramic layer and drying the same to form a film-like body made of a dried photosensitive composition; Step S2) Covering the film with a photomask having a predetermined opening pattern, exposing through the photomask, and partially photocuring the film: (Step S3) etching the film after photocuring And removing the uncured portion of the conductive film.

  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 is typically performed at 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 400 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), an aqueous solution containing an alkaline component such as sodium hydroxide or sodium carbonate can be used for the etching.

Next, a plurality of green sheets for forming a ceramic layer on which an unfired conductive film is formed are stacked 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, seven commercially available silver powders (silver powders a to g) were prepared. These silver powders all have a lightness L ^* of 50 to 80 in the L ^* a ^* b ^* color system based on JIS Z 8781: 2013.
Further, silver powder h 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 this coating solution and stirred for 1 hour. Next, a solid content was recovered from the coating solution and dried at 100 ° C. Thus, a silver powder (silver-zirconia core-shell particles) surface-coated with zirconium butoxide in an amount of 0.5 part by mass in terms of zirconium oxide (ZrO ₂ ) based on 100 parts by mass of the silver powder was obtained. Thus, silver powder h was prepared.

Next, the amounts of organic components of the silver powders a to h were measured using the thermogravimetric device under the above-mentioned heating conditions. The results are shown in the column of “Amount of organic component” in Tables 1 and 2. Further, in the Tables 1 and 2, gas chromatography - together with the type of surface treatment agent to be detected by mass spectrometry (GC-MS), and D ₅₀ particle size based on volume based on the laser diffraction scattering method, the Shown. In addition, "BTA type" in the column of the surface treatment agent indicates a benzotriazole type compound.

(Preparation of photosensitive composition)
First, silver powder and a vehicle shown in Tables 1 and 2 were prepared. The vehicle comprises a urethane acrylate monomer as a photosensitive resin, Irgacure 369 (registered trademark) (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator, an organic binder, a polymerization inhibitor, a sensitizer, It was prepared by dissolving a gelation inhibitor and an ultraviolet absorber in dipropylene glycol methyl ether acetate and dihydroterpineol as organic solvents. Then, photosensitive compositions (Examples 1 to 8 and Comparative Examples 1 to 7) were prepared by mixing the silver powder and the vehicle at a mass ratio of 77:23.

(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, this was dried at 60 ° C. for 15 minutes to form a film on a green sheet. Next, a photomask was placed over the film. At this time, a photomask having a wiring pattern with a line width of 20 μm and an interval (space) between adjacent lines of 20 μm (L / S = 20 μm / 20 μm) was used. With this photomask covered, light was irradiated at an intensity of 2500 mJ / cm ² by an exposure machine to partially cure the film. After the exposure, a 0.1% by mass aqueous solution of Na ₂ CO ₃ was sprayed on the ceramic green sheet to etch away the uncured film portion, and then washed with pure water and dried at room temperature. Thus, a wiring pattern (spiral pattern) in which the wiring was arranged in a spiral was produced.

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

・ Evaluation of residue:
The wiring pattern was observed with an electron microscope, and the residue was evaluated from the obtained observation image. The observation image was taken at a magnification of 200 times. Then, the number of line-to-line residues remaining in the space between the wirings in the observation image was counted. In addition, the counting of the residue between lines was performed for a plurality of visual fields, and the arithmetic average value was defined as the number of residues between lines. The results are shown in the column of “Evaluation of residue” in Tables 1 and 2. The notation in this column is as follows.
"O": Number of residue between lines is 0 / field (no residue between lines was confirmed)
“△”: Number of residue between lines is 1 to 3 / field “×”: Number of residue between lines is 4 or more / field

・ Evaluation of peeling:
From the observation image, the presence or absence of peeling and disconnection was confirmed. The results are shown in the column of "Evaluation of peeling" in Tables 1 and 2. The notation in this column is as follows.
"○": No peeling "X": Peeling

・ 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. The results are shown in the column of “line width” in Tables 1 and 2. The notations in the evaluation column are as follows.
“○”: 20 to 25 μm (target value)
“△”: 25 to 28 μm
“×”: 28 μm or more

·Comprehensive evaluation:
"O": There is no x in each of the above-described evaluations of residue, peeling, and line width. "X": There is 1 or more x in each of the above-described evaluations of residue, peeling, and line width.

As shown in Table 1, in Comparative Example 1 using only the silver powder a having a small amount of the organic component, the wiring pattern had a large variation in line width, and the line width was thickened in some places. As a result, the average line width was too large than the target value, and it was difficult to form a stable fine line. The reason for this is that the photo-curing property of the conductive film was too high, so that light scattered from the opening of the photomask partially cured the conductive film in the light-shielding portion, and the conductive film was resistant to etching. It is conceivable that the removal of the uncured portion was incomplete at the time of etching because the property was too high.
Further, in Comparative Example 2 using only silver powder b having a relatively large amount of organic components, peeling and disconnection were frequently observed in the wiring pattern, and it was difficult to form the wiring pattern. This may be because the hardened portion flows along with the unhardened portion during etching.
Further, in Comparative Example 3 using only silver powder e having a fatty acid and a benzotriazole-based compound adhered to the surface, many peelings and disconnections were observed in the wiring pattern, and it was difficult to form a fine line. Further, a large amount of residue between lines remains in the space between the lines.

  In contrast to Comparative Examples 1 to 3, in Examples 1 to 4, there was no interline residue by using silver powder a and silver powder b in combination, and the line width was suppressed to 28 μm or less, and further to 25 μm or less. The obtained fine line wiring pattern could be formed with high resolution. That is, it was possible to form a fine-line wiring pattern in which there was no peeling, disconnection, or short-circuit failure of the wiring, and a stable space was secured between the wirings.

Table 2 further studies a mixed system of two or more types of silver powder.
As shown in Table 2, Examples 5 and 6 in which silver powder c or silver powder d were used instead of silver powder b, and Examples 7 in which silver powder g was further used in addition to silver powder a and silver powder b, Also in Example 8 in which silver powder h was used instead of silver powder a, fine line wiring patterns could be formed with high resolution, as in Examples 1 to 3.
On the other hand, in Comparative Examples 4 to 6, in which silver powders e to g were used instead of silver powder b, and in Comparative Example 7, in which the total of silver powder a and silver powder b was reduced to 80% of the entire silver powder, A large amount of residue between lines remained in the space between the lines. In Comparative Examples 5 and 6, the wiring pattern had a large variation in line width, and the line width was slightly larger than the target value.

From the above results, the first conductive powder having an organic component amount of 0.1% by mass or less based on thermogravimetric analysis and a benzotriazole-based compound adhered to the surface, and the organic component amount based on thermogravimetric analysis By using together with at least 0.5% of the second conductive powder and making the sum of them a proportion of 90% by mass or more of the whole conductive powder, the fine line wiring pattern with little interline residue can be improved. It was found that it could be formed at a resolution.
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 (9)

Including a conductive powder and a photosensitive organic component,
The conductive powder,
D ₅₀ particle size based on volume based on the laser diffraction scattering method is at 1μm or more 5μm or less,
The following two types:
(1) a first conductive powder having an organic component amount of 0.1% by mass or less based on thermogravimetry;
(2) surface is adhered benzotriazole compound, Ri organic component amount of at least 0.5% by mass based on thermogravimetry, and the benzotriazole when the entire organic components is 100 mol% compound accounts for more than 50 mol%, the second conductive powder;
Wherein the total of the components occupies 90% by mass or more when the entirety of the conductive powder is 100% by mass. The conductive powder contains silver-based particles,
The photosensitive composition according to claim 1. The mass ratio between the first conductive powder and the second conductive powder is such that first conductive powder: second conductive powder = 85: 15 to 20:80,
The photosensitive composition according to claim 1. The first conductive powder is a core-shell particle including a metal material serving as a core and a ceramic material covering at least a part of a surface of the core.
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. Further comprising an organic solvent having a boiling point of 150 ° C or higher and 250 ° C or lower;
The photosensitive composition according to claim 1.   A composite comprising: a green sheet; and a conductive film disposed on the green sheet and comprising a dried body of the photosensitive composition according to claim 1.   An electronic component comprising a conductive layer formed of the fired body of the photosensitive composition according to claim 1.   After applying the photosensitive composition according to any one of claims 1 to 6 on a substrate, performing photo-curing and etching treatment, baking, and comprising a fired body of the photosensitive composition. A method for manufacturing an electronic component, comprising a step of forming a conductive layer.

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