KR20200097774A - Photosensitive composition and its use - Google Patents

Abstract

According to the present invention, a photosensitive composition comprising a conductive powder and a photosensitive organic component is provided. The conductive powder has a volume-based D ₅₀ particle diameter of 1 to 5 μm based on a laser diffraction/scattering method, and the following two types: (1) The first conductivity in which the amount of organic components based on thermogravimetric analysis is 0.1 mass% or less. powder; (2) The sum of the components of the second conductive powder, wherein the benzotriazole-based compound is adhered to the surface and the amount of organic components based on thermogravimetric analysis is at least 0.5% by mass; the total of the conductive powder is 100% by mass. When it does, it occupies 90 mass% or more.

Description

Photosensitive composition and its use

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

In addition, this application claims priority based on Japanese Patent Application No. 2017-239464 for which it applied on December 14, 2017, and the entire contents of the application are incorporated by reference in this specification. .

In the manufacture of electronic components such as inductors, a method of forming a conductive layer by a so-called photolithographic method using a photosensitive composition containing a conductive powder and a photosensitive organic component is known (see, for example, Patent Documents 1 to 5). ). In the related method, first, a photosensitive composition is applied on a substrate by a printing method or the like, and dried to form a film-like body. Next, the formed film-like body is covered with a photomask having a predetermined opening pattern, and the film-like body is exposed through the photomask. Thereby, the exposed film-like body part is photocured. Next, the portion of the uncured film-like body that has been shielded from light with the photomask is removed by corrosion cleaning with an etching solution. Then, by firing this, a conductive layer patterned into a desired shape is formed (printed). According to this method, a conductive layer having a fine pattern can be formed as compared to the case of using various conventional printing methods.

Patent Document 1: Japanese Patent No. 5163687 Patent Document 2: Pamphlet of International Publication No. 2015/122345 Patent Document 3: Japanese Patent Application Publication No. 2016-138310 Patent Document 4: Japanese Patent No. 5352768 Patent Document 5: Japanese Patent Application Publication No. 2006-193795

However, in recent years, the miniaturization and high performance of various electronic devices are rapidly progressing, and further miniaturization and higher density are required for electronic components mounted in electronic devices. Along with this, in the manufacture of electronic components, reduction in resistance of the conductive layer and thinning (narrowing) are required. For example, it is required to form a fine line conductive layer having a width (line width) of 30 µm or less and further 20 µm or less of the wiring constituting the conductive layer.

However, according to the study of the present inventors, it was difficult to form a conductive layer with high resolution when the photosensitive composition described in the above patent document was used. As an example, it was difficult to stably form a thin wire by making the line width thicker or the like. In addition, as another example, when forming a wiring pattern, as shown in the schematic diagram of FIG. 2, residues that could not be completely removed by etching in the gaps (spaces) between adjacent wirings (hereinafter referred to as ``interline residues'' There was a thing that remained here and there. As a result, a leakage current may occur due to the tunnel effect, or a short circuit failure may occur due to a connection between wirings.

The present invention has been made in view of such a point, and an object thereof is to provide a photosensitive composition capable of forming a fine line conductive layer with few interline residues with high resolution. Further, another object related is to provide a composite including a conductive film made of a dried product of such a photosensitive composition. In addition, another object related is to provide an electronic component including a conductive layer made of a fired body of such a photosensitive composition, and a method for producing the same.

According to the present invention, a photosensitive composition comprising a conductive powder and a photosensitive organic component is provided. The conductive powder has a volume-based D ₅₀ particle diameter of 1 μm or more and 5 μm or less based on a laser diffraction/scattering method, and the following two types: (1) the amount of organic components based on thermogravimetric analysis is 0.1 mass% or less, First conductive powder; (2) The sum of the components of the second conductive powder, wherein the benzotriazole-based compound is adhered to the surface and the amount of organic components based on thermogravimetric analysis is at least 0.5% by mass; the total of the conductive powder is 100% by mass. When it does, it occupies 90 mass% or more.

In the 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 accounts for 90% by mass or more of the total conductive powder. By using the first electroconductive powder and the second electroconductive powder together in this way, for example, compared to the case of using these individually, it is possible to form a fine line conductive layer stably. In addition, since the second conductive powder contains the benzotriazole-based compound, it is difficult for the interline residue to remain, and a space can be stably secured between the wiring lines. Therefore, it is possible to reduce the leakage current and suppress the occurrence of short circuit failure. In addition to the above effects, a high-resolution conductive layer can be formed.

In a preferred aspect disclosed herein, the conductive powder contains silver particles. Thereby, a conductive layer excellent in balance between cost and low resistance can be realized.

In a preferred embodiment disclosed herein, the mass ratio of the first conductive powder and the second conductive powder is the first conductive powder: the second conductive powder = 85:15 to 20:80. Thereby, the effect of the technique disclosed here can be exhibited at a higher level. For example, even as a conductive layer with a further advanced fine line formation, it can be formed with high precision.

In a preferred embodiment disclosed herein, the first conductive powder is a core shell particle comprising a metal material serving as a core and a ceramic material covering at least a part of the surface of the core. Thereby, the stability of the electroconductive powder in the photosensitive composition can be improved better and a highly durable conductive layer can be realized. In addition, for example, in an application in which a ceramic electronic component is manufactured by forming a conductive layer on a ceramic substrate, the integrity with the ceramic substrate can be improved.

In a preferred embodiment disclosed herein, in the L ^* a ^* b ^* color system based on JIS Z 8781:2013, the brightness L ^* of the conductive powder is 50 or more. As a result, light stably reaches the deep portion of the uncured conductive film during exposure, and the thick conductive layer can be stably realized.

In a preferred embodiment disclosed herein, an organic solvent having a boiling point of 150°C or more and 250°C or less is further included. Thereby, the storage stability of the photosensitive composition and the handling property at the time of forming a conductive film can be improved, and the drying temperature after printing can be suppressed 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 formed of a dried body of the photosensitive composition.

Further, according to the present invention, an electronic component provided with a conductive layer made of a fired body of the photosensitive composition is provided. According to the photosensitive composition, it is possible to stably realize a fine line conductive layer with few interline residues. For this reason, it is possible to suitably realize an electronic component provided with a small and/or high-density conductive layer.

In addition, according to the present invention, an electronic component comprising a step of applying the photosensitive composition on a substrate, performing photocuring and etching treatment, and then firing, and forming a conductive layer made of a fired body of the photosensitive composition. A manufacturing method is provided. According to such a manufacturing method, it is possible to suitably manufacture an electronic component provided with a small and/or high-density conductive layer.

1 is a cross-sectional view schematically showing a structure of a multilayer chip inductor according to an embodiment.
[Fig. 2] Fig. 2 is a schematic diagram for explaining interline residue.

Hereinafter, preferred embodiments of the present invention will be described. In addition, matters other than matters specifically mentioned in the present specification (for example, conductive powder contained in the photosensitive composition), matters necessary for the practice of the present invention (for example, the preparation method of the photosensitive composition, the conductive film or the conductive layer The formation method, the manufacturing method of an electronic component, etc.) can be understood based on the technical content taught by this specification and the general technical common sense of those skilled in the relevant field. The present invention can be implemented based on the content disclosed in this specification and the common technical knowledge in the field.

In addition, in the following description, a film-like body (dried product) dried at a temperature equal to or lower than the boiling point of a benzotriazole-based compound (approximately 200°C or lower, for example 100°C or lower) is referred to as a "conductive film". The conductive film includes the entire unbaked (before firing) film-like body. The conductive film may be an uncured product before photocuring or a cured product after photocuring. In the following description, a sintered product (fired product) obtained by firing the conductive composition at a sintering temperature of the conductive powder or higher is referred to as a "conductive layer". The conductive layer includes a wiring (line body), a wiring pattern, and a solid pattern. In addition, in this specification, the notation of "A to B" showing 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 firing the photosensitive composition. In the technique disclosed herein, the conductive powder is a mixed powder containing at least a first conductive powder and a second conductive powder. And, when the total of the 1st electroconductive powder and the 2nd electroconductive powder is 100 mass %, it occupies 90 mass% or more. Thereby, 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 contain conductive powders other than those. From the viewpoint of exerting the effect 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, and more preferably 98% by mass or more of the total conductive powder. .

The first conductive powder is a conductive powder in which the amount of organic components is kept low. The organic component contained in the conductive powder is mainly derived from an organic surface coating agent adhered to the surface of the conductive powder, or a residual organic component used in the production of the conductive powder, for example, an organic solvent. In addition, about the organic surface coating agent, it demonstrates in detail in the column of 2nd electroconductive powder mentioned later.

In the technique disclosed here, the amount of the organic component in the first conductive powder is 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 in the conductive powder the first conductive powder whose organic component amount is suppressed in this way, the etching resistance of the conductive film can be improved, and the cured conductive film portion can be appropriately fixed on the substrate even after the etching treatment. Therefore, it can suppress that the conductive film peels or the wiring becomes too thin. 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 1st electroconductive powder may or may not contain an organic component intentionally or inevitably (it may be less than a 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 adhered to the surface or may contain a residual solvent. When the first conductive powder contains an organic surface coating agent, it is preferable to contain the same kind as the organic surface coating agent of the second conductive powder. For example, it is preferable to contain a benzotriazole-based compound.

In addition, in this specification, "the amount of organic components" means the mass decay rate measured according to the following measurement method. That is, first, as a sample for measurement, a predetermined amount of conductive powder is weighed, and the sample for measurement is subjected to a temperature increase rate of 10°C/min in an air atmosphere at room temperature ( 25°C) to 600°C. Then, the mass change (mass decay rate) before and after heating is calculated by the following formula: amount of organic components (%) = [(mass before heating)-(mass after heating to 600°C)]/(mass before heating) Х100; The mass decay rate thus obtained is referred to as the amount of organic components. The unit is mass%.

The second conductive powder is a conductive powder having a larger amount of organic components than the first conductive powder. In the technique disclosed herein, a benzotriazole-based compound is adhered to the surface of the second conductive powder. The benzotriazole-based compound is an organic surface coating agent. In the second conductive powder, the amount of organic components is at least 0.5% by mass. The second conductive powder is not particularly limited, except that the benzotriazole-based compound has adhered to the surface and the amount of the organic component is at least 0.5% by mass. By including the second conductive powder in the conductive powder, the peelability of the uncured portion can be improved during the etching treatment, and the wiring can be suppressed from becoming too thick. In addition, it is difficult for the interline residue to remain in the space between the interconnections, and a space can be stably secured between the interconnections. Therefore, it is possible to suppress the occurrence of short circuit failure while reducing the leakage current.

From the above viewpoint, the amount of the organic component of the second conductive powder is preferably 0.7% by mass or more, preferably 0.75% by mass or more, and may be, for example, 0.8% by mass or more. 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 in 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 properties of the conductive powder. The benzotriazole-based compound may be a compound having a benzotriazole skeleton. As a suitable example, a compound having one or two or more structural moieties of 1H-benzotriazole represented by the following (1) or a structural moiety of 2H-benzotriazole, which is its tautomer, is mentioned.

As specific examples of the benzotriazole-based compound, 1H-benzotriazole, 2H-benzotriazole, 2-(2'-hydroxy-5'-methylphenyl) benzotriazole, 2-(2'-hydroxy-3' ,5'-di-t-butylphenyl) 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-meth) Acryloxy) propoxybenzophenone, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3'-t -Butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3', 5'-di-t-butylphenyl)-5-chlorobenzotriazole, etc. are mentioned. . Among them, it is preferable not to contain a halogen element (for example, fluorine or chlorine).

The organic component contained in the second conductive powder is typically mainly made of a benzotriazole-based compound (a component occupying 50 mol% or more in a molar ratio). As for the organic component of the 2nd conductive powder, the benzotriazole-type compound should just occupy 80 mol% or more, and should just be comprised by the benzotriazole-type compound further. The second conductive powder is another organic surface known to be usable 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. You may further include a coating agent. For example, when the total amount of the organic component of the second conductive powder is 100 mol%, in addition to the benzotriazole-based compound, other organic surface coating agents are approximately 50 mol% or less, preferably 10 mol% or less, more Preferably, you may contain it in a ratio of 5 mol% or less. It is more preferable that the second conductive powder does not contain fatty acids such as carboxylic acid as an organic surface coating agent. Thereby, the effect of the technique disclosed here can be exhibited at a higher level. In addition, that the organic surface coating agent contains a benzotriazole-based compound can be confirmed by, for example, a gas chromatography-mass spectrometry (GC-MS) method.

Although not particularly limited, the mass ratio of the first conductive powder and 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, it is 60:40 to 20:80, especially, it is good to be 60:40 to 40:60. Thereby, the effect of the technique disclosed here can be exhibited at a higher level. For example, even as a conductive layer in which fine lines have been further advanced, it can be formed with high resolution and with high precision. Further, by including the first conductive powder in a ratio of a predetermined value or more, the proportion of components that are burnt 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 type or two or more types can be appropriately selected and used from among conventionally known ones, respectively. As a suitable example, gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), aluminum (Al), nickel (Ni), ruthenium (Ru), rhodium (Rh), Simple metals such as tungsten (W), iridium (Ir), and osmium (Os), and mixtures and alloys thereof. As an alloy, silver alloys, such as silver-palladium (Ag-Pd), silver-platinum (Ag-Pt), and silver-copper (Ag-Cu), are mentioned, for example.

In one suitable aspect, the first conductive powder and/or the second conductive powder contain silver-based particles. Silver is relatively inexpensive and has high electrical conductivity. For this reason, by containing silver-based particles, a conductive layer excellent in balance between cost and low-resistance can be realized. The silver-based particles may be those containing a silver component. As an example, a single substance of silver, the above-described silver alloy, and core shell particles containing silver-based particles as a core may be mentioned.

In another suitable aspect, the first conductive powder and/or the second conductive powder contain metal-ceramic core shell particles. The metal-ceramic core-shell particles cover at least a part of the surface of the core portion and a core portion made of a metal material, and have a coating portion made of a ceramic material. Ceramic materials are excellent in chemical stability, heat resistance, and durability. For this reason, by adopting the shape of the metal-ceramic core shell particles, the stability of the conductive powder in the photosensitive composition can be better improved, and a highly durable conductive layer can be realized. In addition, for example, in applications in which a conductive layer is formed on a ceramic substrate and a ceramic electronic component is manufactured, by including the metal-ceramic core shell particles, the integrity with the ceramic substrate can be improved, and after firing Peeling and disconnection of the conductive layer can be suitably suppressed.

Among them, it is preferable that the first conductive powder with a small amount of organic components contains metal-ceramic core shell particles, and it is more preferable that the first conductive powder is composed of metal-ceramic core shell particles. The first conductive powder having a small amount of organic components tends to have relatively low stability and storage properties in the conductive composition compared to the second conductive powder having a large amount of organic components. When the first conductive powder contains the metal-ceramic core shell particles, it is possible to compensate for the low amount of organic components and improve the stability and storage properties of the entire conductive composition.

In the metal-ceramic core shell particles, examples of the metal material constituting the core portion include the above-described metal alone, and mixtures and alloys thereof. Among them, silver-based particles are preferred for the reasons described above. In other words, it is preferable that the first conductive powder and/or the second conductive powder contain silver-ceramic core shell particles.

Although not particularly limited, examples of the ceramic material constituting the metal-ceramic covering portion include zirconium oxide (zirconia), magnesium oxide (magnesia), aluminum oxide (alumina), silicon oxide (silica), and titanium oxide (titania ), oxide-based materials such as cerium oxide (ceria), yttrium oxide (yttria), and barium titanate; Composite oxide-based materials such as cordierite, mullite, forsterite, steatite, sialon, zircon, and ferrite; Nitride-based materials such as silicon nitride (silicon nitrite) and aluminum nitride (aluminum nitrite); Carbide-based materials such as silicon carbide (silicon carbide); Hydroxide-based materials such as hydroxyapatite; And the like. For example, in the use of forming a conductive layer on a ceramic substrate and manufacturing a ceramic electronic component, a ceramic material such as a ceramic substrate or excellent in affinity 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 per 100 parts by mass of the metal material in the core part. In addition, metal-ceramic core shell particles can be produced according to a conventionally known method. For example, as described in paragraphs 0025 to 0028 of Japanese Patent No. 5075222, which is the source of the applicant of the present application, a metal material and an organic metal compound (for example, a metal alkoxide or chelate compound) or an oxide sol having a target metal element It can be produced by making it react.

The conductive powder has a D ₅₀ particle diameter of 1 to 5 μm in balance with exposure performance. By setting the particle diameter of D ₅₀ in the above range, the exposure performance of the uncured conductive film can be improved, and a fine line conductive layer can be stably formed. Each of the first conductive powder and the second conductive powder should have a _D50 particle size within the above range. From the viewpoint of suppressing aggregation of the conductive powder and improving the stability of the conductive composition, the D ₅₀ particle diameter of the conductive powder may be, for example, 1.5 μm or more and 2.0 μm or more. From the viewpoint of improving fine lines, densification, and low resistance of the conductive layer, the particle diameter of D ₅₀ of the conductive powder may be, for example, 4.5 μm or less and 4.0 μm or less. In addition, in this specification, "D ₅₀ particle diameter" means a particle diameter corresponding to the integrated value 50% from the smaller of the particle diameter in the particle size distribution based on volume based on the laser diffraction/scattering method.

Although not particularly limited, the D ₅₀ particle diameter of the first conductive powder and the second conductive powder may be at least 0.5 μm, typically 0.5 to 3.0 μm, for example, about 1.0 to 2.0 μm. In other words, it is sufficient that the particle size distribution of the entire conductive powder has multimodality. In one specific example, the particle diameter of D ₅₀ of the first conductive powder with a small amount of organic components is in the range of about 3 to 5 μm, for example, 3.5 to 4.5 μm, and the particle diameter of D ₅₀ of the second conductive powder with a large amount of organic components is , About 1 to 3.5 μm, for example 1.5 to 3 μm. Thereby, compared with the case where the difference between the particle diameter of D ₅₀ of the 1st electroconductive powder and the 2nd electroconductive powder is small, the compactness and packing property of a conductive layer can be improved. As a result, it is possible to suitably increase the resistance of the conductive layer.

Although not particularly limited, the shape of the conductive particles constituting the conductive powder is typically a roughly spherical shape having an average aspect ratio (long/short axis ratio) of about 1 to 2, preferably 1 to 1.5, for example It is a concept of 1~1.2 people. Thereby, exposure performance can be realized more stably. The first conductive powder and the second conductive powder may each have an average aspect ratio within the above range. In addition, in this specification, the "average aspect ratio" refers to the arithmetic average value of the aspect ratio calculated from the observation image obtained by observing a plurality of electroconductive particles with an electron microscope. In addition, in the present specification, "spherical shape" refers to a form that can be viewed as a generally spherical (ball) as a whole, and is a term that can include an elliptical shape, a polygonal shape, a disk spherical shape, and the like.

Although not particularly limited, the entire conductive powder may have a lightness L ^* of 50 or more in the L ^* a ^* b ^* color system based on JIS Z 8781:2013. As a result, irradiation light stably reaches the deep part of the uncured conductive film during exposure, and a thick conductive layer such as, for example, 5 μm or more, and further 10 μm or more can be stably realized. From the above viewpoint, the brightness L ^* of the conductive powder may be approximately 55 or higher, for example, 60 or higher. The brightness L ^* can be adjusted by, for example, the type of the conductive powder described above and the particle size of D ₅₀ . In addition, the measurement of the brightness L ^* can be performed, for example, with a spectrophotometer conforming to JIS Z 8722:2009.

Although not particularly limited, the proportion of the conductive powder occupied in the entire photosensitive composition may be approximately 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 electrical conductivity can be formed. In addition, it is possible to improve the handling properties of the photosensitive composition and workability when forming the conductive film.

<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 curing by irradiation of light energy such as ultraviolet rays. In the present specification, the "photosensitive organic component" refers to the overall photopolymerizable or photomodified organic compound. As a suitable example, a mixture comprising a photosensitive resin having an unsaturated bond and a photopolymerization initiator generating active species; So-called diazo resins (for example, condensation products of aromatic bisazide and formaldehyde); A mixture containing an addition polymerizable compound such as an epoxy compound and a photo acid generator such as a diallyl iodonium salt; Naphthoquinone diazide compounds; 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 decomposition of a photopolymerization initiator. The polymerization reaction may be an addition polymerization or a ring-opening polymerization. The photosensitive resin contains a monomer, polymer, and oligomer having one or more unsaturated bonds and/or cyclic structures. As the photosensitive resin, one or two or more types can be appropriately selected and used from among those known in the art, depending on the use or the type of the substrate. As a suitable example, a radical polymerizable monomer having at least one radical polymerizable reactive group such as a (meth)acryloyl group or a vinyl group may be mentioned. Among them, a (meth)acrylate monomer having a (meth)acryloyl group is preferable. By including the (meth)acrylate monomer, the flexibility of the conductive layer and the followability to the substrate can be improved. As a result, the occurrence of defects such as peeling or disconnection can be suppressed to a higher level. In addition, in this specification, "(meth)acryloyl" includes "methacryloyl" and "acryloyl", and "(meth)acrylate" refers to "methacrylate" and "acrylic It is a term including "rate".

The (meth)acrylate monomer includes a monofunctional (meth)acrylate having one functional group per molecule, a polyfunctional (meth)acrylate having two or more functional groups per molecule, and modified products thereof. . As specific examples of the (meth)acrylate monomer, triethylene glycol monoacrylate, triethylene glycol monomethacrylate, tetraethylene glycol monoacrylate, tetraethylene glycol monomethacrylate, pentaerythritol triacrylate, pentaeryth Polyfunctional (meth)acrylates such as ryitol trimethacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate, and urethane having a urethane bond (-NH-C(=O)-O-) (Meth)acrylate, etc. are mentioned. Among them, it is preferable that the (meth)acrylate monomer contains a urethane (meth)acrylate. As a result, the etch resistance of the exposed portion can be better improved, and the stretchability and flexibility of the conductive film can be further improved. Therefore, it is possible to increase the integrity with the substrate. Further, from the viewpoint of enhancing photocurability, a monomer having 5 or more (meth)acryloyl groups per molecule of the (meth)acrylate monomer is preferable. The ratio of the urethane (meth)acrylate occupied in the entire photosensitive resin is, on a volume basis, preferably 30% by volume or more, such as 50% by volume or more.

The photopolymerization initiator is a component that decomposes by irradiation with light such as ultraviolet rays to generate active species such as radicals and cations, thereby starting the polymerization reaction of the photosensitive resin. As a photoinitiator, one type or two or more types can be appropriately selected and used from among those known in the art, depending on the type of photosensitive resin and the like. As a suitable example, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl )-Butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, 2,4-diethylthioxanthone, Benzophenone etc. are mentioned.

Although not particularly limited, the proportion of the photosensitive organic compound occupied in the whole photosensitive composition may be approximately 0.1 to 25% by mass, typically 0.5 to 20% by mass, for example 1 to 15% by mass. In addition, 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. In addition, 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 an organic dispersion medium for dispersing these in addition to the essential components described above. The organic dispersion medium is a component that imparts appropriate viscosity and fluidity to the photosensitive composition, improves the handling property of the photosensitive composition, or improves the workability when forming a conductive film. As the organic dispersion medium, one or two or more types can be appropriately selected and used from among those known in the art, depending on the kind of the photosensitive organic compound, and the like. As a suitable example, alcohol-based 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), and butyl galbitol (diethylene glycol monobutyl ether); Ester systems such as diethylene glycol monobutyl ether acetate, dipropylene glycol methyl ether acetate, butyl glycol acetate, butyl diglycol acetate, butyl cellosolve acetate, butyl galbitol acetate (diethylene glycol monobutyl ether acetate), and isobornyl acetate solvent; Hydrocarbon solvents such as toluene, xylene, naphtha, and petroleum hydrocarbons; Mineral spirit; And organic solvents such as.

Among them, from the viewpoint of improving the storage stability of the photosensitive composition and the handling properties at the time of forming the conductive film, an organic solvent having a boiling point of 150°C or higher, and further, an organic solvent of 170°C or higher is preferable. Further, as another suitable example, from the viewpoint of lowering the drying temperature after printing the conductive film, an organic solvent having a boiling point of 250° C. or less, and further, an organic solvent having a boiling point of 220° C. or less are preferable. Thereby, productivity can be improved and production cost can be reduced.

Further, for example, in the use of manufacturing ceramic electronic components by forming a conductive layer on a ceramic substrate, an organic solvent having low permeability to the ceramic green sheet is preferable. Examples of the organic solvent having low permeability to the ceramic green sheet include an organic solvent having a sterically bulky structure such as a cyclohexyl group or a tert-butyl group, and an organic solvent having a relatively large molecular weight. In addition, for example, an organic solvent having low permeability to the ceramic green sheet as described above, and an organic solvent capable of appropriately dissolving the components contained in the photosensitive composition (for example, photosensitive organic components), in an arbitrary ratio It is also preferable to mix with and use as an organic type dispersion medium.

As an organic solvent having the above-described properties (boiling point and permeability to ceramic green sheet), for example, Doanol DPM (trademark) (boiling point: 190°C, manufactured by Dow Chemical Company), Dowanol DPMA (Trademark) (Boiling point: 209°C, manufactured by Dow Chemical Company), Mentanol (Boiling Point: 207°C), Mentanol P (Boiling Point: 216°C), Isopa H (Boiling Point: 176°C, manufactured by Kanto Fuel Co., Ltd.) , SW-1800 (boiling point: 198°C, manufactured by Maruzen Petroleum Corporation), and the like.

When the photosensitive composition contains an organic dispersion medium, it is not particularly limited, but the proportion of the organic dispersion medium occupied in the whole photosensitive composition is approximately 1 to 50 mass%, typically 3 to 30 mass%, for example 5 to 20 mass It may be %.

<Organic Binder>

The photosensitive composition may contain an organic binder in addition to the above essential components. The organic binder is a component that enhances adhesion between the uncured conductive film and the substrate. As the organic binder, one or two or more types may be appropriately selected and used from among those known in the art, depending on the type of the photosensitive organic compound or the substrate. As a suitable example, cellulose polymers such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and hydroxy methyl cellulose, acrylic resins, phenol resins, alkyd resins, polyvinyl alcohol, polyvinyl butyral, and the like may be mentioned. In particular, when an alkaline aqueous solution is used for etching, a hydroxyl group (-OH), a carboxyl group (-C(=O)OH), an ester bond (-C(=O)O-), a sulfo group (- A compound having an acidic structural moiety such as SO ₃ H) is preferred. Further, from the viewpoint of being easily removed by etching, a hydrophilic organic binder such as a cellulose polymer or an acrylic resin is preferable.

<Other ingredients>

The photosensitive composition can add various additive components as necessary in addition to the essential components described above, as long as the effect of the technique disclosed herein is not significantly impaired. As an additive component, one type or two or more types can be appropriately selected and used from those known in the art. Examples of the additive component include, for example, inorganic fillers, photosensitizers, polymerization inhibitors, radical scavengers, antioxidants, light absorbers, ultraviolet absorbers, plasticizers, surfactants, leveling agents, thickeners, dispersants, defoaming agents, and anti-gelling agents. , Stabilizers, antioxidants, preservatives, colorants, pigments, and the like. Although not particularly limited, the proportion of the additive component occupied in the entire photosensitive composition may be approximately 5% by mass or less, for example 3% by mass or less.

<Use of the photosensitive composition>

According to the photosensitive composition disclosed herein, it is possible to stably form a fine-line conductive layer having less interline residue and, for example, a line width finer than 30 μm and further fine line width than 20 μm, with high resolution. have. Further, peeling or disconnection of the conductive layer can be reduced. In addition, it is possible to reduce the leakage current and suppress the occurrence of short circuit failure. Therefore, the photosensitive composition disclosed herein can be suitably used for formation of a conductive layer in various electronic components such as inductance components, capacitor components, and multilayer circuit boards, for example.

Electronic components are of various types of mounting, such as a surface mounting type and a through-hole mounting type. The electronic component may be a laminated type, a winding 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.

In addition, the photosensitive composition in which the conductive powder contains metal-ceramic core shell particles can be suitably used for formation of a conductive layer of a ceramic electronic component. In addition, in this specification, the "ceramic electronic component" includes the whole electronic component which has an amorphous ceramic base material (glass ceramic base material) or a crystalline (that is, non-glass) ceramic base material. Typical examples include a high frequency filter having a ceramic substrate, a ceramic inductor (coil), a ceramic capacitor, a low temperature fired ceramics substrate (LTCC substrate), and a high temperature fired multilayer ceramic substrate (High Temperature Co- fired Ceramics Substrate: HTCC substrate).

1 is a cross-sectional view schematically showing the structure of a multilayer chip inductor 1. In addition, the dimensional relationship (length, width, thickness, etc.) in FIG. 1 does not necessarily reflect the actual dimensional relationship. In addition, symbols X and Y in the drawings represent the left and right directions and the vertical directions, respectively. However, this is only a direction for convenience of explanation.

The multilayer chip inductor 1 includes a body portion 10 and external electrodes 20 provided on both side portions of the body portion 10 in the left-right direction X. The shape of the multilayer chip inductor 1 is, for example, a size such as a 1608 shape (1.6 mm x 0.8 mm) and a 2520 shape (2.5 mm x 2.0 mm).

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 can constitute, for example, a covering portion of conductive powder, and is made of a ceramic material as described above. In the vertical direction Y, an internal electrode layer 14 is disposed between the ceramic layers 12. The internal electrode layer 14 is formed using the photosensitive composition described above. The internal electrode layers 14 adjacent in the vertical direction (Y) with the ceramic layer 12 interposed therebetween are conducted through the vias 16 provided in the ceramic layer 12. Thereby, the internal electrode layer 14 is comprised in a three-dimensional spiral shape (helix shape). Both ends of the internal electrode layer 14 are connected to the external electrode 20, respectively.

This 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 this is supplied onto a carrier sheet to form a ceramic green sheet. Then, the ceramic green sheet is rolled and then cut to a desired size to obtain a plurality of ceramic layer forming green sheets. Then, via holes are appropriately formed at predetermined positions of the plurality of ceramic layer forming green sheets using a perforator or the like.

Then, a conductive film having a predetermined coil pattern is formed at predetermined positions on the plurality of ceramic layer forming green sheets using the photosensitive composition described above. As an example, the following steps: (Step S1) a step of forming a film-like body made of a dried body of a photosensitive composition by applying and drying the photosensitive composition on a green sheet for forming a ceramic layer; (Step S2) Step of covering the film body with a photomask having a predetermined opening pattern and exposing through the photomask to partially photocure the film body: (Step S3) The film body after photocuring is etched to remove the uncured portion. The unbaked conductive film can be formed by a manufacturing method including a removing step.

In addition, in forming a conductive film using the photosensitive composition, a conventionally known method can be appropriately used. For example, in (Step S1), application of the photosensitive composition can be performed using various printing methods such as screen printing, a bar coater, or the like. Drying of the photosensitive composition may be performed typically at 50 to 100°C. In the exposure in (Step S2), for example, an exposure machine that emits light in a wavelength range of 10 to 400 nm, for example, UV irradiation such as a high-pressure mercury lamp, a metal halide lamp, or a xenon lamp can be used. In (Step S3), in etching, an aqueous solution containing an alkali component such as sodium hydroxide or sodium carbonate can be used.

Then, a plurality of green sheets for forming a ceramic layer on which an unfired conductive film is formed are stacked and pressed. Thereby, a laminate of an unfired ceramic green sheet is produced. Then, the laminated body of the ceramic green sheet is fired at, for example, 600 to 1000°C. As a result, the ceramic green sheet is integrally sintered to form the body portion 10 including the ceramic layer 12 and the internal electrode layer 14 made of a fired body of a photosensitive composition. Then, the external electrode 20 is formed by applying an appropriate external electrode forming paste to both ends of the main body 10 and firing. In the manner described above, the multilayer chip inductor 1 can be manufactured.

Hereinafter, several examples relating to the present invention will be described, but it is not intended to limit the present invention to those shown in these examples.

(Preparation of silver powder)

First, seven types of commercially available silver powders (silver powders a to g) were prepared. In addition, all of these silver powders have a brightness L ^* of 50 to 80 in the L ^* a ^* b ^* color system based on JIS Z 8781:2013.

Moreover, silver powder h was prepared using silver powder a. Specifically, first, zirconium butoxide was added to methanol to prepare a coating liquid. Next, silver powder a was added to this coating liquid and stirred for 1 hour. Next, the solid content was recovered from the coating liquid and dried at 100°C. This obtained 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 ) with respect to 100 parts by mass of the silver powder. In this way, silver powder h was prepared.

Next, using a thermogravimetric measuring device, the amounts of organic components in the silver powder a to h were measured under the above-described heating conditions, respectively. The results are shown in the column of "the amount of organic components" in Tables 1 and 2. In Tables 1 and 2, the types of surface treatment agents detected by gas chromatography-mass spectrometry (GC-MS) and the volume-based D ₅₀ particle size based on laser diffraction and scattering are also shown. In addition, "BTA system" in the column of a surface treatment agent represents a benzotriazole system compound.

(Preparation of photosensitive composition)

First, silver powders and vehicles shown in Tables 1 and 2 were prepared. The vehicle includes a urethane acrylate monomer as a photosensitive resin, Irgacure 369 (registered trademark) (manufactured by Chiba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator, an organic binder, a polymerization inhibitor, a sensitizer, a gelation inhibitor, and , An ultraviolet absorber was prepared by dissolving in dipropylene glycol methyl ether acetate and dihydro terpineol as organic solvents. And the photosensitive composition (Examples 1-8, Comparative Examples 1-7) was prepared by mixing silver powder and a vehicle at a mass ratio of 77:23.

(Production of wiring pattern)

First, using a stainless steel screen, the prepared photosensitive composition was applied onto a commercially available ceramic green sheet, respectively. Next, this was dried at 60° C. for 15 minutes to form a film-like body on a green sheet. Next, a photomask was applied from the top of the membranous body. At this time, as the photomask, a line width of the wiring pattern was 20 μm, and a spaced portion (space) of adjacent lines was 20 μm (L/S = 20 μm/20 μm). With this photomask covered, light was irradiated with an intensity of 2500 mJ/cm ² by an exposure machine to partially cure the film-like body. After exposure, 0.1% by mass of Na ₂ CO ₃ aqueous solution was sprayed onto the ceramic green sheet to remove the uncured film-like body by etching, washed with pure water, and dried at room temperature. Thereby, a wiring pattern (spiral pattern) in which the wiring was arranged in a swirling state was produced.

(Evaluation of wiring pattern)

Regarding the produced wiring pattern, residue, peeling, and line width 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 200 times magnification. Then, the number of interline residues remaining in the space between the wirings in the observation image was counted. In addition, the count of the interline residue was performed with respect to a plurality of fields of view, and the arithmetic mean value of the interline residue in the plurality of fields was set as "the number of interline residues". The result is shown in the column of "evaluation of the residue" in Tables 1 and 2. The notation of the corresponding column is as follows.

「○」: Number of residuals between lines, 0 pieces/field of view (no residuals between lines were confirmed)

「△」: Number of residues between lines, 1~3 pieces/field of view

「Х」: Number of residues between lines, 4 or more/field of view

·Evaluation of peeling:

From the observation image, the presence or absence of peeling and disconnection was confirmed. The result is shown in the column of "evaluation of peeling" in Tables 1 and 2. The notation of the corresponding column is as follows.

"○": no peeling

"Х": there is peeling

・Evaluation of line width:

From the observation image, the line width of the wiring pattern was measured. In addition, measurement of the line width was performed with respect to a plurality of fields of view, and the arithmetic mean value was taken as the line width. The results are shown in the column of "line width" in Tables 1 and 2. In addition, notation of the column of evaluation is as follows.

「○」: 20~25μm (target value)

「△」: 25~28μm

「Х」: 28μm or more

· Comprehensive evaluation:

"○": In each evaluation of the above-described residue, peeling, and line width, there is no Х

"Х": In each evaluation of the above-described residue, peeling, and line width, there is at least one Х

As shown in Table 1, Comparative Example 1 is a test example using only silver powder a with a small amount of organic components. In Comparative Example 1, the variation in line width was large in the wiring pattern, and it was confirmed that the line width was thickened in various places. As a result, the average line width became too large than the target value, and it was difficult to form a stable fine line. The reason for this is that the photocurability of the conductive film was too high, and a part of the conductive film in the light-shielding portion was cured with light scattered from the opening portion of the photomask, or the etching resistance of the conductive film was too high. It is conceivable that the removal of the uncured part was incomplete. In addition, Comparative Example 2 is a test example using only silver powder b with a relatively large amount of organic components. In Comparative Example 2, many peeling and disconnection were observed in the wiring pattern, and formation of the wiring pattern was difficult. As this reason, it is conceivable that the hardened part flowed out together with the uncured part at the time of etching. In addition, Comparative Example 3 is a test example using only silver powder e to which fatty acids and benzotriazole-based compounds adhere to the surface. In Comparative Example 3, many peeling and disconnection were observed in the wiring pattern, and formation of fine lines was difficult. In addition, a lot of interline residue remained in the space between the lines.

Examples 1 to 4 are test examples in which silver powder a and silver powder b are used in combination. In Examples 1 to 4, compared to Comparative Examples 1 to 3, there was no interline residue, and a fine line wiring pattern having a line width of 28 μm or less, and further suppressed to 25 μm or less could be formed with high resolution. In other words, 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 space was stably secured between the wirings.

In Table 2, an investigation is further conducted on a mixture system of two or more types of silver powder. Examples 5 and 6 are test examples using silver powder c or silver powder d by replacing silver powder b. Example 7 is a test example using silver powder g in addition to silver powder a and silver powder b. Example 8 is a test example using silver powder h by replacing silver powder a. As shown in Table 2, in Examples 5 and 6, 7 and 8, as in Examples 1 to 4, a fine line wiring pattern could be formed with high resolution.

On the other hand, Comparative Examples 4 to 6 are test examples using silver powders e to g, respectively, by changing the silver powder b. Comparative Example 7 is a test example in which the total of the silver powder a and the silver powder b is reduced to 80% of the total silver powder. In Comparative Examples 4 to 6 and Comparative Example 7, a lot of interline residues remained in the space between the wirings. In addition, in Comparative Examples 5 and 6, the variation in line width was large in the wiring pattern, 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 second conductive powder having a benzotriazole-based compound adhering to the surface and an organic component amount of at least 0.5% based on thermogravimetric analysis. It was found that by using the powder together and making the total ratio of 90% by mass or more of the entire conductive powder, a wiring pattern of fine lines with few interline residues can be formed with high resolution. These results show the significance of the technology disclosed herein.

As mentioned above, although this invention was demonstrated in detail, these are only examples, and various changes can be added to this invention within the range which does not deviate from the subject matter.

1 multilayer chip inductor
10 Body
12 ceramic layer
14 Internal electrode layer
20 external electrodes

Claims (9)

Containing conductive powder and a photosensitive organic component,
The conductive powder has a volume-based D ₅₀ particle diameter of 1 μm or more and 5 μm or less based on a laser diffraction/scattering method, and the following two types:
(1) a first conductive powder having an organic component amount of 0.1% by mass or less based on thermogravimetric measurement;
(2) a second conductive powder having a benzotriazole-based compound adhering to the surface and having an organic component amount of at least 0.5% by mass based on thermogravimetric measurement;
The photosensitive composition, wherein the sum of the components of occupies 90 mass% or more when the total of the conductive powder is 100 mass%. The method according to claim 1,
The photosensitive composition in which the said electroconductive powder contains silver particle. The method according to claim 1 or 2,
The photosensitive composition, wherein the mass ratio of the first conductive powder and the second conductive powder is the first conductive powder: the second conductive powder = 85:15 to 20:80. The method according to any one of claims 1 to 3,
The photosensitive composition, wherein the first conductive powder is a core shell particle comprising a metal material serving as a core and a ceramic material covering at least a part of a surface of the core. The method according to any one of claims 1 to 4,
JIS Z 8781: In the L ^* a ^* b ^* color system based on 2013, the lightness L ^* of the said electroconductive powder is 50 or more, The photosensitive composition. The method according to any one of claims 1 to 5,
The photosensitive composition further comprises an organic solvent having a boiling point of 150°C or more and 250°C or less. 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 any one of claims 1 to 6. An electronic component comprising a conductive layer made of a fired body of the photosensitive composition according to any one of claims 1 to 6. An electronic component comprising a step of applying the photosensitive composition of any one of claims 1 to 6 on a substrate, performing photocuring and etching treatment, and then firing to form a conductive layer made of a fired body of the photosensitive composition. Manufacturing method.

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