Magnetic composition, magnetic film, laminate, and circuit member

Abstract

A magnetic composition containing a magnetic powder, a thermosetting component, and a rubber component, wherein the rubber component includes at least one selected from the group consisting of a butadiene rubber, a silicone rubber, a styrene-butadiene rubber, an acrylic rubber, an acrylic block copolymer, and a styrene-based block copolymer.

Description

Magnetic composition, magnetic film, laminate and circuit member

[0001] The present disclosure relates to a magnetic composition, a magnetic film, a laminate, and a circuit member.

[0002] Materials containing metal powders with various physical properties are used depending on the characteristics required for industrial products. For example, magnetic materials containing magnetic powders are used in the fields of inductors, electromagnetic wave shields, bonded magnets, etc. (See, for example, Patent Document 1).

[0003] JP 2014-127624 A

[0004] When the magnetic material is used in the form of a film, the film-like magnetic material (magnetic film) must be flexible so that it can be easily handled during production, cutting, use, and the like.

[0005] Therefore, some aspects of the present disclosure have an object to provide a magnetic composition capable of forming a magnetic film having good flexibility, and a magnetic film made of the magnetic composition. Also, some aspects of the present disclosure have an object to provide a laminate including the magnetic film, and a circuit member including a layer made of a cured product of the magnetic composition.

[0006] The present inventors have discovered that a specific rubber component significantly improves the flexibility of the magnetic film, and have completed the present disclosure.

[0007] In some aspects, the present disclosure provides the following [1] to

[10] .

[0008] [1] A magnetic composition comprising a magnetic powder, a thermosetting component, and a rubber component, wherein the rubber component comprises at least one selected from the group consisting of butadiene rubber, silicone rubber, styrene-butadiene rubber, acrylic rubber, acrylic block copolymer, and styrene block copolymer.

[0009] [2] The magnetic composition according to [1], wherein the content of the magnetic powder is 70 mass % or more based on the total mass of nonvolatile matter in the magnetic composition.

[0010] [3] The magnetic composition according to [1] or [2], which contains particles containing the rubber component.

[0011] [4] The magnetic composition according to [3], wherein the average particle size of the particles containing the rubber component is 10 to 2000 nm.

[0012] [5] The magnetic composition according to any one of [1] to [4], wherein the content of the rubber component is 0.05 to 10.0 mass% based on the total mass of nonvolatile matter in the magnetic composition.

[0013] [6] The magnetic composition according to any one of [1] to [5], wherein the thermosetting component contains an epoxy group-containing compound and a phenol-based curing agent.

[0014] [7] A magnetic film comprising the magnetic composition according to any one of [1] to [6].

[0015] [8] A laminate comprising a support and the magnetic film according to [7] provided on the support.

[0016] [9] A circuit member comprising: a substrate having wiring provided on its surface; and a magnetic layer provided so as to fill gaps between the wiring of the substrate, wherein the magnetic layer comprises a cured product of the magnetic composition according to any one of [1] to [6].

[0017]

[10] The circuit member according to [9], wherein the wiring is a coil wiring of an inductor.

[0018] According to some aspects of the present disclosure, it is possible to provide a magnetic composition capable of forming a magnetic film having good flexibility, and a magnetic film comprising the magnetic composition. Also, according to some aspects of the present disclosure, it is possible to provide a laminate comprising the magnetic film, and a circuit member comprising a layer comprising a cured product of the magnetic composition.

[0019] 1A to 1C are schematic cross-sectional views showing an example of a method for manufacturing a circuit member according to an embodiment of the present disclosure.

[0020] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. Furthermore, unless specifically stated otherwise, the units of the numerical values ​​before and after "to" are the same. In the numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of a numerical range of another stage. Furthermore, in the numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the examples. Furthermore, the upper and lower limits individually described can be arbitrarily combined. Furthermore, "A or B" may include either A or B, or may include both. Furthermore, unless otherwise specified, the materials exemplified below may be used alone or in combination of two or more. When multiple substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0021] Hereinafter, embodiments of the present disclosure will be described, but the present disclosure is not limited to the following embodiments.

[0022] <Magnetic Composition> The magnetic composition of one embodiment contains a magnetic powder, a thermosetting component, and a rubber component. In one embodiment, the rubber component includes at least one selected from the group consisting of butadiene rubber, silicone rubber, styrene-butadiene rubber, acrylic rubber, acrylic block copolymer, and styrene block copolymer.

[0023] The magnetic composition of the embodiment containing the specific rubber component allows the production of a magnetic film with good flexibility. The magnetic film made of the magnetic composition of the embodiment also tends to have excellent flexibility after curing. Furthermore, with the recent trend toward miniaturization of circuit components such as inductors, the gaps between the wiring of circuit components to which magnetic materials are applied have become increasingly narrow, making it difficult to sufficiently embed the magnetic material between the wiring. However, when the composition contains particles containing the specific rubber component, a magnetic film with excellent embeddability (ability to embed the gaps between wiring) is easily obtained.

[0024] (Magnetic powder) The magnetic powder is an aggregate of magnetic particles. The magnetic particles contain at least a magnetic component. The magnetic particles may contain only one type of magnetic component, or may contain multiple types of magnetic components. The magnetic particles may consist of only the magnetic component, or may further contain components other than the magnetic component. The content of the magnetic component based on the total mass of the magnetic particles may be 20% by mass or more, 50% by mass or more, or 80% by mass or more.

[0025] The magnetic component includes, for example, a metal element. The metal element included in the magnetic component may be, for example, at least one element selected from the group consisting of base metal elements, noble metal elements, transition metal elements, and rare earth elements. The metal element may be, for example, at least one element selected from the group consisting of iron (Fe), copper (Cu), titanium (Ti), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), niobium (Nb), aluminum (Al), tin (Sn), chromium (Cr), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), praseodymium (Pr), neodymium (Nd), samarium (Sm), and dysprosium (Dy).

[0026] The magnetic component may be a single metal element or an alloy composed of two or more metal elements. The alloy may include at least one selected from the group consisting of solid solutions, eutectics, and intermetallic compounds. The alloy may be, for example, stainless steel such as an Fe—Cr alloy or an Fe—Ni—Cr alloy. It may also be a copper alloy such as a Cu—Sn alloy, a Cu—Sn—P alloy, a Cu—Ni alloy, or a Cu—Be alloy.

[0027] The magnetic component may be a powder of a metal compound containing the above-mentioned metal element and an element other than the above-mentioned metal element. The element other than the above-mentioned metal element may be, for example, at least one element selected from the group consisting of carbon (C), oxygen (O), beryllium (Be), phosphorus (P), boron (B), and silicon (Si). The metal compound may be, for example, a metal oxide such as iron oxide. The metal compound may also be a sintered body containing a metal oxide as a main component (for example, a sintered body obtained by mixing and sintering a metal oxide with a metal element such as cobalt, nickel, or manganese).

[0028] The magnetic component may be a soft magnetic alloy or a ferromagnetic alloy. The magnetic component may be, for example, at least one selected from the group consisting of an Fe—Si alloy, an Fe—Si—Al alloy (Sendust), an Fe—Ni alloy (Permalloy), an Fe—Cu—Ni alloy (Permalloy), an Fe—Co alloy (Permendur), an Fe—Cr—Si alloy (electromagnetic stainless steel), an Nd—Fe—B alloy (rare earth magnet), an Sm—Fe—N alloy (rare earth magnet), an Al—Ni—Co alloy (Alnico magnet), and a ferrite. The ferrite may be, for example, a spinel ferrite, a hexagonal ferrite, or a garnet ferrite.

[0029] To obtain a higher magnetic permeability, the magnetic powder may contain at least one powder selected from the group consisting of elemental Fe and Fe-based alloys. The Fe-based alloy may be, for example, at least one selected from the group consisting of Fe—Si-based alloys, Fe—Si—Al-based alloys, Fe—Ni-based alloys, Fe—Cu—Ni-based alloys, Fe—Co-based alloys, Fe—Cr—Si-based alloys, Fe—Si—B-based alloys, and Fe—Si—B—P—Nb—Cr-based alloys. To obtain an even higher magnetic permeability, the magnetic powder may contain Fe amorphous alloy powder.

[0030] Amorphous Fe alloys are amorphous powders obtained by rapidly quenching a high-temperature melt of Fe, the primary component, together with other elements such as Si. These amorphous Fe alloy powders are also known as metallic glasses. Amorphous Fe alloy powders can be produced according to methods well known in the art. Commercially available products include those manufactured by Epson Atmix Corporation under the product names AW2-08 and KUAMET-6B2, those manufactured by Daido Steel Co., Ltd. under the product names DAPMS3, DAPMS7, DAPMSA10, DAPPB, DAPPC, DAPMKV49, DAP410L, DAP430L, and DAPHYB, and those manufactured by Kobe Steel, Ltd. under the product names MH45D, MH28D, MH25D, and MH20D. These amorphous Fe alloy powders may be used alone or in combination.

[0031] The entire or part of the surface of the magnetic powder may be coated with a surface treatment agent. The surface treatment agent may be, for example, an inorganic surface treatment agent such as an inorganic oxide, a phosphoric acid compound, a phosphate compound, or a silane coupling agent, an organic surface treatment agent such as montan wax, or a cured resin. The coupling agent described below may also be used as the surface treatment agent.

[0032] The magnetic powder (e.g., magnetic powder containing an Fe-based alloy) may have the entire or part of its surface coated with an insulating material. That is, the magnetic powder may include magnetic particles whose surfaces are coated with an insulating material (hereinafter referred to as "insulating-coated magnetic particles"). Examples of insulating materials include silica, titania, calcium phosphate, montan wax, and cured epoxy resins. The insulating-coated magnetic particles may be Fe amorphous alloy powder having an insulating coating. The thickness of the inorganic oxide coating that constitutes the insulating coating may be, for example, 1 to 100 nm.

[0033] As the insulating coated magnetic particles, for example, "KUAMET9A4" (Fe-Si-B alloy, D) manufactured by Epson Atmix Corporation is used. ５０ : 20 μm, with insulating coating), "SAP-2DC" manufactured by Shinto Kogyo Co., Ltd. (Fe-Si-B-P-Nb-Cr alloy, D ５０ These insulating coated magnetic particles may be used in combination with magnetic particles without an insulating coating. For example, soft ferrite powder "BSN-125" (Ni-Zn ferrite, D) manufactured by Toda Kogyo Co., Ltd. ５０ : 10 μm, without insulating coating) may be used in combination.

[0034] The shape of the magnetic particles is not particularly limited. The magnetic particles may be, for example, spherical, ellipsoidal, flat, plate-like, rod-like, or needle-like. From the viewpoint of further improving the ability to fill gaps between wirings, the shape of the magnetic particles may be spherical. Here, "spherical" means that the average aspect ratio, which is the ratio of the major axis to the minor axis (major axis / minor axis) of the magnetic particles measured by the following method, is 1.0 to 4.0. In this specification, the average aspect ratio is calculated by calculating the ratio of the major axis to the minor axis (major axis / minor axis) for each of 100 randomly selected magnetic particles and averaging the aspect ratios obtained. The major axis of a magnetic particle refers to the distance between two planes that circumscribe the magnetic particle and are parallel to each other, selected so as to maximize the distance between them. The minor axis of a magnetic particle refers to the distance between two planes that circumscribe the magnetic particle and are parallel to each other, selected so as to minimize the distance between them. From the viewpoint of the fluidity and embeddability of the magnetic composition, and from the viewpoint of dense packing of the magnetic particles, the aspect ratio may be 1.0 to 3.0, 1.0 to 2.0, or 1.0 to 1.5.

[0035] The 10% cumulative particle size of the magnetic powder based on volume (hereinafter referred to as "D １０ ") may be 0.6 μm or more, 0.7 μm or more, or 0.8 μm or more from the viewpoint of the fluidity of the magnetic composition. １０ From the viewpoint of dense packing of the magnetic particles and embedding in minute gaps, the D of the magnetic powder may be 2.0 μm or less, 1.9 μm or less, or 1.8 μm or less. １０ may be 0.6 to 2.0 μm, 0.7 to 1.9 μm, or 0.8 to 1.8 μm.

[0036] The 50% cumulative particle size of the magnetic powder based on volume (hereinafter referred to as "D ５０ ") may be 1.1 μm or more, 1.2 μm or more, or 1.3 μm or more in terms of the fluidity and magnetic permeability of the magnetic composition. ５０ From the viewpoint of dense packing of the magnetic particles and embedding in minute gaps, the D of the magnetic powder may be 3.6 μm or less, 3.5 μm or less, or 3.4 μm or less. ５０may be 1.1 to 3.6 μm, 1.2 to 3.5 μm, or 1.3 to 3.4 μm.

[0037] The 90% cumulative particle size of the magnetic powder (hereinafter referred to as "D ９０ ") may be 2.1 μm or more, 2.2 μm or more, or 2.3 μm or more, from the viewpoint of the fluidity and magnetic permeability of the magnetic composition. ９０ From the viewpoint of dense packing of the magnetic particles and embedding in minute gaps, the D of the magnetic powder may be 6.3 μm or less, 6.2 μm or less, or 6.1 μm or less. ９０ may be 2.1 to 6.3 μm, 2.2 to 6.2 μm, or 2.3 to 6.1 μm.

[0038] Here, D １０ D means the particle size at which the cumulative volume of the magnetic powder, starting from the smallest particle size, accounts for 10% of the total magnetic powder volume in the particle size distribution based on volume. ５０ D means the particle size at which the cumulative volume of the magnetic powder, starting from the smallest particle size, accounts for 50% of the total volume of the magnetic powder in the particle size distribution based on volume. ９０ The D of the magnetic powder means the particle size at which the cumulative volume of the magnetic powder, starting from the smallest particle size, accounts for 90% of the total volume of the magnetic powder in the particle size distribution based on volume. １０ , D ５０ and D ９０ The particle size distribution used in the calculation of can be obtained by measuring the particle size distribution using a laser diffraction / scattering particle size distribution analyzer under the conditions described in the Examples.

[0039] Magnetic powder having the particle size distribution described above (for example, D １０ is 0.6 to 2.0 μm, and D ５０ is 1.1 to 3.6 μm, and D ９０When a magnetic powder having a particle size of 2.1 to 6.3 μm is used, the magnetic composition tends to exhibit a low minimum melt viscosity and tends to have excellent gap-filling properties between wirings. The minimum melt viscosity of the magnetic composition can be adjusted appropriately by changing the type and amount of the thermosetting component, rubber component, etc., and can be set to, for example, 10,000 Pa·s or less (e.g., 50 to 10,000 Pa·s) at 120°C. The minimum melt viscosity of the magnetic composition refers to the minimum value of shear viscosity measured by dynamic viscoelasticity measurement of the magnetic composition.

[0040] Magnetic powders having the above-described particle size distribution can be obtained, for example, by atomization, chemical vapor deposition (CVD), liquid phase synthesis, etc. The particle size distribution of the magnetic powder produced by the above-described method may be adjusted using a pulverizer, ball mill, bead mill, air classifier, wet sieving machine, sieve, etc. The method of adjusting the particle size distribution to the desired size using a classifier, sieve, etc., allows the particles to maintain their spherical shape, making it easier to obtain magnetic powders with excellent fluidity, compared to methods of adjusting the particle size distribution by applying force to particles to pulverize them using a pulverizer, ball mill, etc., and structural defects and crystal distortions at the interfaces caused by pulverization are less likely to occur, making it easier to obtain magnetic powders with excellent magnetic permeability.

[0041] The content of the magnetic powder may be 70% by mass or more, 75% by mass or more, or 80% by mass or more, based on the total mass of the nonvolatile content in the magnetic composition, from the viewpoint of obtaining higher magnetic permeability. The content of the magnetic powder may be 97% by mass or less, 95% by mass or less, or 93% by mass or less, based on the total mass of the nonvolatile content in the magnetic composition, from the viewpoint of further improving the ability to fill gaps between wirings. From these viewpoints, the content of the magnetic powder may be 70 to 97% by mass, 75 to 95% by mass, or 80 to 93% by mass, based on the total mass of the nonvolatile content in the magnetic composition. Here, the nonvolatile content in the magnetic composition refers to the components contained in the magnetic composition other than the volatile components. The volatile components refer to components that show a mass loss of 10% by mass or more when heated at 180°C for 60 minutes and components with a boiling point of 300°C or less.

[0042] (Thermosetting Component) The thermosetting component includes, for example, a thermosetting compound. The thermosetting component may further include a curing agent for the thermosetting compound, and may further include a curing accelerator.

[0043] [Thermosetting Compound] The thermosetting compound is a compound that cures, for example, by heat treatment alone or by reacting with a curing agent. The thermosetting compound may be a monomer, or may be a compound (oligomer or polymer) having a structural unit formed by polymerization of a monomer, generally called a thermosetting resin. From the viewpoint of improving the shape retention of the magnetic film, which is a molded product of the magnetic composition, the thermosetting compound may contain a thermosetting resin.

[0044] The thermosetting resin can function as a binder resin that binds the magnetic powder, and examples of the thermosetting resin include epoxy resin, phenol resin, acrylic resin, polyimide resin, and polyamide-imide resin.

[0045] The weight average molecular weight of the thermosetting resin is, for example, 150 or more, and may be 400 to 1,000,000. The weight average molecular weight in this specification is a value measured by gel permeation chromatography (GPC) and converted into standard polystyrene.

[0046] The content of the thermosetting resin may be, for example, 100% by mass, 0 to 99% by mass, 10 to 98% by mass, or 20 to 97% by mass based on the total mass of the thermosetting compound.

[0047] In order to enhance curability, the thermosetting compound may contain a compound having one or more epoxy groups in the molecule (hereinafter referred to as an "epoxy group-containing compound"). The content of the epoxy group-containing compound may be, for example, 100% by mass, 0 to 99% by mass, 20 to 95% by mass, or 30 to 90% by mass based on the total mass of the thermosetting compound.

[0048] The epoxy group-containing compound may be a compound generally known as an epoxy resin (e.g., an oligomer or polymer having two or more epoxy groups in the molecule). Examples of such compounds include biphenyl-type epoxy resins, stilbene-type epoxy resins, diphenylmethane-type epoxy resins, sulfur-containing epoxy resins, novolac-type epoxy resins, biphenyl novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, salicylaldehyde-type epoxy resins, naphthol- and phenol-copolymerized epoxy resins, epoxidized aralkyl-type phenolic resins, bisphenol-type epoxy resins, glycidyl ether-type epoxy resins of alcohols, glycidyl ether-type epoxy resins of paraxylylene- and / or metaxylylene-modified phenolic resins, and terpene-modified epoxy resins. At least one selected from the group consisting of glycidyl ether-type epoxy resins of phenolic resins, cyclopentadiene-type epoxy resins, glycidyl ether-type epoxy resins of polycyclic aromatic ring-modified phenolic resins, glycidyl ether-type epoxy resins of naphthalene ring-containing phenolic resins, glycidyl ester-type epoxy resins, glycidyl or methylglycidyl-type epoxy resins, alicyclic epoxy resins, halogenated phenol novolac-type epoxy resins, hydroquinone-type epoxy resins, trimethylolpropane-type epoxy resins, and linear aliphatic epoxy resins obtained by oxidizing olefin bonds with peracids such as peracetic acid may be used. Among these, biphenyl novolac-type epoxy resins may be used from the viewpoint of further enhancing curability. The content of the epoxy resin may be, for example, 10 to 100% by mass, 20 to 100% by mass, or 30 to 100% by mass, based on the total mass of the epoxy group-containing compound.

[0049] The epoxy group-containing compound may be a compound generally known as a reactive diluent (e.g., an epoxy group-containing compound having a molecular weight of 100 to 700). Examples of such compounds include at least one selected from the group consisting of n-butyl glycidyl ether, versatate glycidyl ether, styrene oxide, ethylhexyl glycidyl ether, phenyl glycidyl ether, butylphenyl glycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, diethylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether. The content of the epoxy group-containing compound having a molecular weight of 100 to 700 may be, for example, 0 to 95% by mass, 0 to 80% by mass, or 0 to 60% by mass, based on the total mass of the epoxy group-containing compound.

[0050] The epoxy group-containing compound may include an epoxy group-containing compound that is liquid at 25°C. "Liquid at 25°C" means that the viscosity of the epoxy group-containing compound at 25°C is 200 Pa·s or less. The viscosity is measured using an E-type viscometer under the following conditions: temperature: 25°C, rotor: SPP, and rotation speed: 2.5 rpm. Examples of epoxy group-containing compounds that are liquid at 25°C include bisphenol-type liquid epoxy resins such as bisphenol A-type liquid epoxy resins, bisphenol F-type liquid epoxy resins, bisphenol AD-type liquid epoxy resins, bisphenol S-type liquid epoxy resins, and hydrogenated bisphenol A-type liquid epoxy resins; naphthalenediol-type liquid epoxy resins; aminoglycidyl ether-type liquid epoxy resins, and phenol novolac-type liquid epoxy resins. The epoxy group-containing compound that is liquid at 25°C may be one that has been blended as a dispersion medium for rubber particles, which will be described later. From the viewpoint of improving the flexibility and embeddability of the magnetic film, at least one selected from the group consisting of bisphenol-type liquid epoxy resins and phenol novolac-type liquid epoxy resins may be used as the epoxy group-containing compound that is liquid at 25° C. The content of the epoxy group-containing compound that is liquid at 25° C. may be, for example, 0 to 100% by mass, 10 to 90% by mass, or 20 to 80% by mass based on the total mass of the epoxy group-containing compound.

[0051] The epoxy group-containing compound may be a combination of an epoxy group-containing compound that is liquid at 25° C. and an epoxy group-containing compound that is non-liquid (solid) at 25° C. In this case, a biphenyl novolac epoxy resin may be used as the epoxy group-containing compound that is non-liquid (solid) at 25° C., from the viewpoint of further enhancing curability. Note that "non-liquid (solid) at 25° C." means that the viscosity of the epoxy group-containing compound at 25° C. is greater than 200 Pa s.

[0052] The epoxy equivalent of the epoxy group-containing compound may be 80 to 500 g / eq, 100 to 400 g / eq, or 150 to 350 g / eq. The epoxy equivalent of the epoxy group-containing compound can be measured in accordance with JIS K 7236. When the thermosetting compound contains multiple types of epoxy group-containing compounds, the epoxy equivalent measured for a mixture of all of the epoxy group-containing compounds may be in the above range.

[0053] [Curing Agent] The curing agent can be a known curing agent corresponding to the thermosetting compound. For example, when the thermosetting compound is an epoxy group-containing compound, a compound that reacts with the epoxy group of the epoxy group-containing compound to form a cured product can be used. Specific examples of curing agents for epoxy group-containing compounds include phenol-based curing agents, acid anhydride-based curing agents, amine-based curing agents, imidazole-based curing agents, and imidazoline-based curing agents. Among these, phenol-based curing agents may be used from the viewpoint of enhancing curability. Note that amine-based curing agents (more specifically, tertiary amines), imidazole-based curing agents, and imidazoline-based curing agents can also be used as curing accelerators in combination with other curing agents (e.g., phenol-based curing agents).

[0054] The phenolic curing agent is a compound having at least two phenol groups in the molecule. Examples of the phenolic curing agent include novolak-type phenolic resins obtained by condensing or co-condensing phenols such as phenol, cresol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol and / or naphthols such as α-naphthol, β-naphthol, and dihydroxynaphthalene with aldehydes such as formaldehyde, benzaldehyde, and salicylaldehyde under an acidic catalyst; phenol-aralkyl resins synthesized from phenols and aralkyl phenolic resins such as biphenylene-type phenol-aralkyl resins and naphthol-aralkyl resins; dicyclopentadiene-type phenolic resins synthesized by copolymerizing phenols and / or naphthols with dicyclopentadiene; triphenylmethane-type phenolic resins; terpene-modified phenolic resins; paraxylylene- and / or metaxylylene-modified phenolic resins; melamine-modified phenolic resins; and phenolic resins obtained by copolymerizing two or more of these. Among these, novolac-type phenolic resins may be used from the viewpoint of further enhancing curability.

[0055] The content of the curing agent can be determined by taking into account the ratio between the number of equivalents of reactive groups in the thermosetting compound and the number of equivalents of active groups in the curing agent that react with the reactive groups. The number of equivalents of active groups in the curing agent per equivalent of reactive groups in the thermosetting compound may be 0.5 to 1.5 equivalents, 0.9 to 1.4 equivalents, or 1.0 to 1.2 equivalents. For example, when an epoxy-containing compound is used as the thermosetting compound and a phenolic curing agent is used as its curing agent, the ratio can be expressed as the number of equivalents of phenolic hydroxyl groups in the phenolic curing agent per equivalent of epoxy groups in the epoxy group-containing compound. When the ratio is 0.5 equivalents or more, the effects of suppressing a decrease in curing rate, suppressing decreases in the glass transition temperature and elastic modulus of the resulting cured product, and suppressing a decrease in the insulating reliability of the cured product due to unreacted components are expected. When the ratio is 1.5 equivalents or less, the effects of suppressing a decrease in the mechanical strength of the resulting cured product and suppressing a decrease in the insulating reliability of the cured product due to unreacted components are expected. However, in the above embodiment, the ratio of active groups in the curing agent (the number of equivalents of active groups in the curing agent relative to one equivalent of reactive groups in the thermosetting compound) is not limited, and even if the ratio is outside the above range, the effects of the present disclosure can be obtained.

[0056] [Curing Accelerator] The curing accelerator is not limited as long as it is a compound that can accelerate the curing reaction between a thermosetting compound and a curing agent (for example, the curing reaction between an epoxy group-containing compound and a phenolic curing agent). Examples of curing accelerators include tertiary amines, imidazole curing accelerators, imidazoline curing accelerators, and phosphorus compounds. Among these, imidazole curing accelerators may be used from the viewpoint of enhancing the curing acceleration effect.

[0057] The imidazole curing accelerator is a compound having an imidazole skeleton, and may be an imidazole compound in which hydrogen atoms in the molecule are substituted with substituents. The imidazole curing accelerator may be a compound having an imidazole skeleton, such as an alkyl group-substituted imidazole. Examples of imidazole curing accelerators include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazolepropanenitrile, 1-cyanoethyl-2-phenylimidazole, and 2-isopropylimidazole. As the imidazole curing accelerator, 2-ethyl-4-methylimidazole (for example, "Curesol 2E4MZ" manufactured by Shikoku Chemicals Corporation) may be used from the viewpoint of further enhancing the curing acceleration effect.

[0058] The content of the curing accelerator is not particularly limited as long as it is an amount that can achieve a curing acceleration effect. The content of the curing accelerator may be, for example, 0.001 parts by mass or more, 0.01 parts by mass or more, or 0.1 parts by mass or more, and may be 5 parts by mass or less, 4 parts by mass or less, or 3 parts by mass or less, relative to 100 parts by mass of the total of the thermosetting compound and the curing agent. When the content of the curing accelerator is 0.001 parts by mass or more, a sufficient curing acceleration effect can be easily obtained. When the content of the curing accelerator is 5 parts by mass or less, excellent storage stability can be easily obtained as a magnetic composition. However, even if the content of the curing accelerator is outside the above range, the effects of the present disclosure can be obtained. Note that the curing accelerator may be included as a curing agent, but in this case, the component with the smaller content is considered to be the curing accelerator.

[0059] The content of the thermosetting component may be 3% by mass or more, 4% by mass or more, or 5% by mass or more, based on the total mass of the nonvolatile content in the magnetic composition, from the viewpoint of obtaining a cured product with higher heat resistance. The content of the thermosetting component may be 30% by mass or less, 25% by mass or less, or 20% by mass or less, based on the total mass of the nonvolatile content in the magnetic composition, from the viewpoint of obtaining a higher magnetic permeability. From these viewpoints, the content of the thermosetting component may be 3 to 30% by mass, 4 to 25% by mass, or 5 to 20% by mass, based on the total mass of the nonvolatile content in the magnetic composition.

[0060] (Rubber Component) The rubber component is a compound having rubber elasticity, called a thermosetting elastomer or a thermoplastic elastomer, and specifically, a compound having a Young's modulus measured by a dynamic mechanical analysis device of 0.01 to 100. Such a rubber component contributes to improving the flexibility of the magnetic film, which is a molded product of the magnetic composition, and of the cured product thereof.

[0061] The rubber component may be one of butadiene rubber, silicone rubber, styrene-butadiene rubber, acrylic rubber, acrylic block copolymer, and styrene-based block copolymer, or a combination of two or more of these may be used. The acrylic block copolymer may be, for example, a block copolymer having a block structure of polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate. The styrene-based block copolymer may be, for example, a block copolymer having a block structure of polystyrene-polybutylene-polyethylene-polystyrene. The rubber component may be at least one selected from the group consisting of butadiene rubber, silicone rubber, styrene-butadiene rubber, and acrylic rubber, from the viewpoint of further improving the flexibility of the magnetic film and its cured product and its ability to fill gaps between wirings. Butadiene rubber may be used from the viewpoint of further improving the flexibility and fillability.

[0062] In addition to the rubber components described above (first group rubber components), the rubber component may further contain rubber components (second group rubber components) such as isoprene rubber, butyl rubber, acrylonitrile butadiene rubber, urethane rubber, chloroprene rubber, ethylene propylene rubber, fluororubber, vulcanized rubber, epichlorohydrin rubber, chlorinated butyl rubber, etc. However, from the viewpoint of further improving the flexibility of the magnetic film and its cured product and the ability to fill gaps between wirings, the content of the first group rubber components in the rubber component may be 50% by mass or more, 70% by mass or more, or 90% by mass or more based on the total mass of the rubber component.

[0063] The magnetic composition may contain particles (rubber particles) containing the rubber component. When the rubber component in the magnetic composition is present as particles without dissolving in the thermosetting component, the magnetic composition tends to have a lower melt viscosity and better ability to fill gaps between wirings compared to when the rubber component is present in a dissolved state in the thermosetting component. For the same reason, it becomes possible to increase the amount of magnetic powder blended, making it easier to obtain a higher magnetic constant. The rubber particles may be composed only of the rubber component, but may also contain components other than the rubber component. The content of the rubber component in the rubber particles may be 40% by mass or more, 60% by mass or more, or 80% by mass or more, based on the total mass of the rubber particles.

[0064] The rubber particles may have a core-shell structure. Rubber particles having a core-shell structure may be, for example, particles having a core layer composed of a rubber component and a shell layer composed of a resin. Examples of resins include epoxy-based resins made of polymers containing epoxy group-containing monomers as monomer units (e.g., resins made of a homopolymer of an epoxy group-containing monomer, resins made of a copolymer of an epoxy group-containing monomer and an alkyl (meth)acrylate monomer or other copolymerizable monomer), and acrylic resins made of polymers containing alkyl (meth)acrylate monomers as monomer units (e.g., resins made of a homopolymer of an alkyl (meth)acrylate monomer, resins made of a copolymer of an alkyl (meth)acrylate monomer and an epoxy group-containing monomer or other copolymerizable monomer). Forming a shell layer around the core layer can improve the dispersibility and flowability of the rubber particles.

[0065] Examples of epoxy group-containing monomers include allyl glycidyl ether and glycidyl (meth)acrylate. Examples of alkyl acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and ethylhexyl (meth)acrylate. Other copolymerizable monomers include styrene, α-methylstyrene, 1,4-divinylbenzene, 1- or 2-vinylnaphthalene, (meth)acrylonitrile, 2-methoxyethyl (meth)acrylate, and 2-ethoxyethyl (meth)acrylate. From the viewpoints of storage stability, viscosity, toughness, and adhesion, the resin constituting the shell layer may be a copolymer containing glycidyl methacrylate, methyl methacrylate, and styrene as monomer units.

[0066] The core layer and the shell layer may have a multi-layer structure. In this case, each layer may have a different composition. An adhesive layer may be provided between the core layer and the shell layer.

[0067] From the viewpoint of flexibility and fluidity, the average particle size of the rubber particles may be 10 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more. From the viewpoint of heat resistance, strength, flexibility, uniformity of magnetic properties, and embeddability of the magnetic composition, the average particle size of the rubber particles may be 2000 nm or less, 1000 nm or less, or 500 nm or less. From these viewpoints, the average particle size of the rubber particles may be 10 to 2000 nm, 30 to 2000 nm, 40 to 1000 nm, or 50 to 500 nm. The above average particle size is determined based on the D of the magnetic powder. ５０ The particle size is the 50% cumulative particle size on a volume basis, measured in the same manner as above.

[0068] The content of the rubber component in the magnetic composition may be 0.05% by mass or more, 0.1% by mass or more, 0.3% by mass or more, or 0.5% by mass or more, based on the total mass of nonvolatile content in the magnetic composition, from the viewpoint of further improving the flexibility and magnetic permeability of the magnetic film and its cured product. The content of the rubber component may be 10.0% by mass or less, 5.0% by mass or less, or 3.0% by mass or less, based on the total mass of nonvolatile content in the magnetic composition, from the viewpoint of further improving the adhesion, magnetic properties, low thermal expansion, chemical resistance, and ability to fill gaps between wirings of the magnetic composition. From these viewpoints, the content of the rubber component may be 0.05 to 10.0% by mass, 0.1 to 10.0% by mass, 0.3 to 5.0% by mass, or 0.5 to 3.0% by mass, based on the total mass of nonvolatile content in the magnetic composition. In this embodiment, the content of the rubber particles may be within the above range.

[0069] (Other Components) The magnetic composition may further contain components (other components) other than the magnetic powder, thermosetting component, and rubber component. Examples of other components include a thermoplastic resin, a coupling agent, and a flame retardant.

[0070] [Thermoplastic Resin] The thermoplastic resin may be, for example, at least one selected from the group consisting of acrylic resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate. The content of the thermoplastic resin may be, for example, 0.01 to 1.0 mass% based on the total mass of nonvolatile matter in the magnetic composition.

[0071] [Coupling Agent] The coupling agent contributes to improving the dispersibility of the magnetic powder, improving the adhesion between the thermosetting component and the magnetic powder, and improving the adhesion, flexibility, and mechanical strength of the cured product obtained from the magnetic composition to the substrate. The coupling agent may be, for example, at least one selected from the group consisting of silane-based compounds (silane coupling agents), titanium-based compounds, aluminum compounds (aluminum chelates), and aluminum / zirconium-based compounds. From the viewpoint of enhancing the effect as the coupling agent, the coupling agent may be a silane coupling agent, and may be at least one selected from the group consisting of epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, acid anhydride silane, and vinyl silane. Among these, the use of amino silane can further enhance the effect. Examples of aminosilanes include 3-aminopropyltrimethoxysilane (e.g., KBM-903 manufactured by Shin-Etsu Chemical Co., Ltd.), 3-aminopropyltriethoxysilane (e.g., KBE-903 manufactured by Shin-Etsu Chemical Co., Ltd.), N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (e.g., KBM-603 manufactured by Shin-Etsu Chemical Co., Ltd.), N-2-(aminoethyl)-8-aminooctyltrimethoxysilane (e.g., KBM-6803 manufactured by Shin-Etsu Chemical Co., Ltd.), N-2-(aminoethyl)-3-aminopropyltriethoxysilane (e.g., KBE-603 manufactured by Shin-Etsu Chemical Co., Ltd.), and N-phenyl-3-aminopropyltrimethoxysilane (e.g., KBE-603 manufactured by Shin-Etsu Chemical Co., Ltd.). Examples of suitable coupling agents include KBM-573 manufactured by Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (KBM-602 manufactured by Shin-Etsu Chemical Co., Ltd., etc.), N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane (KBE-602 manufactured by Shin-Etsu Chemical Co., Ltd., etc.), N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane (KBM-575 manufactured by Shin-Etsu Chemical Co., Ltd., etc.), 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine (KBE-9103P manufactured by Shin-Etsu Chemical Co., Ltd., etc.), and X-12-972F (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.). The content of the coupling agent may be, for example, 0.01 to 1.0 mass % based on the total mass of the nonvolatile content in the magnetic composition.

[0072] [Flame Retardant] The flame retardant contributes to the environmental safety, recyclability, moldability, and cost reduction of the magnetic composition. The flame retardant may be, for example, at least one selected from the group consisting of bromine-based flame retardants, phosphorus-based flame retardants, hydrated metal compound-based flame retardants, silicone-based flame retardants, nitrogen-containing compounds, hindered amine compounds, organometallic compounds, and aromatic engineering plastics. The content of the flame retardant may be, for example, 0.01 to 0.5 mass% based on the total mass of the nonvolatile content in the magnetic composition.

[0073] The magnetic composition of this embodiment has, for example, insulating properties. The electrical resistivity of the magnetic composition measured by a resistivity meter is 10 ７ Ω・cm or more, 10 ８ Ω cm or more or 10 ９ The magnetic composition having such an electrical resistivity can be easily obtained by using an insulating thermosetting component.

[0074] <Magnetic Film> The magnetic film of one embodiment is made of the magnetic composition of the above embodiment. That is, the magnetic film of one embodiment contains magnetic powder, a thermosetting component, and a rubber component including at least one selected from the group consisting of butadiene rubber, silicone rubber, styrene-butadiene rubber, acrylic rubber, acrylic block copolymer, and styrene block copolymer. Therefore, the magnetic film of one embodiment has excellent gap-filling properties between wirings and good flexibility.

[0075] The magnetic film may be in the form of a film or a sheet. The thickness of the magnetic film is, for example, 5 to 200 μm. The thickness of the magnetic film may be 0.2 times or more, 0.4 times or more, or 0.6 times or more the depth of the gap between the wirings into which the magnetic composition is embedded.

[0076] The magnetic film can be formed, for example, by mixing and stirring a magnetic powder, a thermosetting component, the specific rubber component, and optionally other components together with an organic solvent to prepare a liquid composition (e.g., a paste) for forming the magnetic film, and then applying the liquid composition onto a support and drying it.

[0077] As the organic solvent, for example, an organic solvent capable of dissolving the thermosetting component can be used. As the organic solvent, an organic solvent that dissolves the thermosetting component but does not dissolve the rubber component can be used. The organic solvent may be, for example, at least one selected from the group consisting of acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene, carbitol acetate, butyl carbitol acetate, cyclohexanone, and xylene. From the viewpoint of workability, the organic solvent may be liquid at room temperature (25°C). From the viewpoint of workability, the boiling point of the organic solvent may be 50°C or higher and 160°C or lower.

[0078] The support may be a polymer film (support film) having heat resistance and solvent resistance, such as a polyester such as polyethylene terephthalate (PET), or a polyolefin such as polypropylene or polyethylene. A metal foil such as copper foil may also be used as the support. Of these, a PET film may be used because it is readily available and has excellent handleability (particularly heat resistance, heat shrinkage, and breaking strength) during the manufacturing process. The thickness of the support is, for example, 1 to 150 μm. The surface of the support may be subjected to a release treatment.

[0079] A cover film may be attached to the magnetic film as needed. That is, in another embodiment, the present disclosure provides a laminate including a magnetic film and a cover film provided on the magnetic film. The cover film may be a polymer film (support film) having heat resistance and solvent resistance, such as a polyester such as polyethylene terephthalate (PET), or a polyolefin such as polypropylene or polyethylene. Among these, a PET or polyethylene film may be used because of its ease of availability and excellent handling properties (particularly heat resistance, heat shrinkage, breaking strength, and releasability) during the manufacturing process and product use. The thickness of the cover film is, for example, 20 to 100 μm. The surface of the cover film may be release-treated.

[0080] The stirring method is not particularly limited, and for example, a stirring blade, a planetary stirring type, a roll mill, a disk mill, or a ball mill can be used.

[0081] Drying may be performed under conditions that volatilize the organic solvent but do not promote curing of the thermosetting component. The drying temperature may be, for example, 60 to 180° C. The drying time may be, for example, 2 to 45 minutes.

[0082] The magnetic film obtained after drying may contain an organic solvent, but the organic solvent content may be 5% by mass or less, 3% by mass or less, or 1% by mass or less, based on the total mass of the magnetic film (i.e., the total mass of the magnetic composition). The magnetic film may be substantially free of organic solvent. That is, the organic solvent content may be 0.5% by mass or less, based on the total mass of the magnetic film.

[0083] The magnetic film described above is used, for example, in circuit components (such as circuit components including inductors) whose characteristics are expected to be improved by the magnetic material. When the magnetic powder has the above-mentioned specific particle size distribution (for example, D １０ is 0.6 to 2.0 μm, and D ５０ is 1.1 to 3.6 μm, and D ９０ When the thickness is 2.1 to 6.3 μm, the magnetic film has excellent filling properties for gaps between wirings, and therefore may be used to fill narrow gaps between wirings in circuit components (for example, gaps with a depth of 20 μm or more and a width of 20 μm or less). However, the magnetic film can be used not only to fill the gaps between wirings (for example, gaps between wirings in a circuit component including an inductor), but also to cover the periphery of a circuit component, as a core material, and the like. The magnetic film can also be used for crosstalk suppression, antenna-in-package, electromagnetic wave shielding, and other applications.

[0084] <Laminate> A laminate of one embodiment includes a support and a magnetic film provided on the support. The laminate is, for example, in the form of a sheet or film. Details of the support and the magnetic film are as exemplified above. The laminate may be used in the manufacture of circuit components, which will be described later. The laminate may further include layers other than the support and the magnetic film. For example, a cover film may be provided on the magnetic film to prevent scratches, dirt, deterioration, and sticking of the magnetic film. Details of the cover film are as exemplified above.

[0085] <Circuit Member> A circuit member of one embodiment includes a substrate having wiring provided on its surface, and a magnetic layer provided so as to fill gaps between the wiring on the substrate.

[0086] The substrate is, for example, a wiring board (circuit board) comprising a substrate and wiring (circuit) provided on the surface of the substrate. Examples of the substrate include substrates made of inorganic materials such as semiconductors, glass, ceramics, and magnetic materials; substrates made of organic materials such as polyimide and polycarbonate; and substrates containing both inorganic and organic materials such as glass / epoxy. The wiring is formed of, for example, gold, silver, copper, or the like. The minimum value of the distance between the wirings (the width of the gap between adjacent wirings) may be 5 μm or less (e.g., 1 to 400 μm). The height of the wiring (the depth of the gap) may be 5 μm or more (e.g., 1 to 200 μm), or may be 20 μm or more, or 90 μm or more.

[0087] The magnetic layer includes a cured product of the magnetic composition of the above embodiment. The magnetic layer is, for example, a cured product of the magnetic film of the above embodiment. The thickness of the magnetic layer is, for example, 5 to 200 μm.

[0088] The circuit member of the embodiment may be, for example, an inductor or an intermediate member for manufacturing an inductor. In either case, the magnetic layer is provided so as to fill the gaps between the coil wirings of the inductor.

[0089] FIG. 1 is a schematic cross-sectional view showing an example of a method for manufacturing a circuit member according to the embodiment. The method for manufacturing a circuit member according to one embodiment includes the steps of preparing a laminate 3 including a support 1 and a magnetic film 2 provided on the support 1, a substrate 11, and a wiring board 10 including wiring 12 provided on the surface 11a of the substrate 11, a step of pressure-bonding the magnetic film 2 to the wiring board 10 so as to cover the wiring 12 (pressure-bonding step), and a step of heating and curing the layer made of the magnetic film 2 (heat-curing step). This method results in a circuit member 100 in which the gaps 12a between the wiring 12 of the wiring board 10 are filled with the layer made of the magnetic film 2, and which includes the wiring board 10 and a magnetic layer 5 formed by curing the layer made of the magnetic film 2. The support 1 may be removed during lamination of the magnetic film 2, or after lamination, before heat-curing the layer made of the magnetic film 2, or after obtaining the magnetic layer 5.

[0090] The method for disposing the magnetic film 2 on the wiring substrate 10 is not particularly limited, but for example, a laminating device equipped with an upper heater 21 and a lower heater 22 can be used, as shown in Fig. 1. In the method shown in Fig. 1, the wiring substrate 10 is first disposed on the lower heater 22 side between the upper heater 21 and the lower heater 22, with the surface of the wiring 12 facing the upper heater 21, and the laminate 3 is disposed on the upper heater 21 side between the upper heater 21 and the lower heater 22, with the magnetic film 2 facing the lower heater 22 (see Fig. 1A). Next, the laminating device is operated, and while heating the laminate 3 and the wiring substrate 10, the laminate 3 is pressed against the wiring substrate 10 from the upper heater 21 side (in the direction of the arrow in Fig. 1A), thereby pressure-bonding the magnetic film 2 to the wiring substrate 10.

[0091] The laminating device may be, for example, a vacuum laminating device such as a vacuum roll laminating device. Lamination may be performed, for example, under conditions of heating and pressing at 40 to 150°C and 0.1 to 1.0 MPa for 0.5 to 10 minutes. Note that a pressing device (e.g., a vacuum pressing device) may also be used instead of the laminating device.

[0092] The heating in the heat curing step can be carried out, for example, under conditions of heating in an inert gas atmosphere such as a nitrogen atmosphere at 80 to 250° C. for 10 to 150 minutes. Heating may also be carried out under a vacuum atmosphere or in the air.

[0093] In the above method, the magnetic film 2 may be partially hardened by heating during the pressure-bonding step. In this case, the pressure-bonding step is also included in the heat-hardening step. However, the heat-hardening step may include a second heating step in which the partially hardened magnetic film 2 is heated, separate from the heating during the pressure-bonding step. The second heating step may be performed under conditions of heating at 80 to 250°C for 10 to 150 minutes in an inert gas atmosphere such as a nitrogen atmosphere. Heating may also be performed in a vacuum atmosphere or in the air.

[0094] The circuit member 100 obtained by the above method is, for example, an intermediate member for producing an inductor. The method for producing a circuit member may further include processes such as via formation, desmearing, electroless plating, and wiring formation on the circuit member 100, and these processes may be repeated multiple times to obtain a circuit member such as an inductor. Wiring can be formed, for example, by performing electroless plating, forming a resist corresponding to the wiring pattern, performing electrolytic copper plating, and then stripping the resist and flash etching.

[0095] The contents of the present disclosure will be described in more detail below using examples and comparative examples, but the present disclosure is not limited to the following examples.

[0096] <Preparation of magnetic powder> As magnetic powder A, metallic glass magnetic powder "SAP-2DC" (Fe-Si-B-P-Nb-Cr alloy with insulating coating) manufactured by Shinto Kogyo Co., Ltd. was used. １０ is 1.10 μm, D ５０ is 2.25 μm, D ９０ The D of magnetic powder A was 3.93 μm. １０ , D ５０ and D ９０was obtained by measuring the particle size distribution using a laser diffraction / scattering particle size distribution analyzer under the following conditions. [Conditions] Magnetic powder and cyclohexanone were weighed to prepare a magnetic powder dispersion of approximately 50% by mass. The prepared dispersion was dispersed for 90 seconds using an ultrasonic disperser, and then placed in a particle size distribution analyzer (LS 13 320 manufactured by Beckman Coulter, laser diffraction method) to measure the particle size distribution of the magnetic powder.

[0097] Example 1: Kaneka Corporation's "MX-136" (a mixture of bisphenol-type liquid epoxy resin and rubber particles having a core-shell structure (core layer: butadiene rubber, shell layer: acrylic resin) dispersed in the resin, rubber particle content: 25% by mass, average particle diameter D ５０ 5.00 g of epoxy resin "NC-3000-H" (biphenyl novolac epoxy resin) manufactured by Nippon Kayaku Co., Ltd., 7.50 g of curing agent "HP-850N" (novolac phenolic resin) manufactured by Resonac Co., Ltd., and 9.47 g of "cyclohexanone" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. were weighed out. These were placed in a 250 ml ointment container as raw materials, and all raw materials in the ointment container were stirred and kneaded with a rotary and revolutionary mixer. The rotary and revolutionary mixer was an "ARE-310" manufactured by Thinky Corporation. The stirring and kneading was performed twice over 20 minutes, with the revolution speed of the rotary and revolutionary mixer set to 2000 rpm. Next, 0.09 g of a curing accelerator "2E4MZ" (2-ethyl-4-methylimidazole) manufactured by Shikoku Chemical Industry Co., Ltd. was added to the mixture obtained by stirring and kneading, and the revolution speed of the rotary and revolutionary mixer was set to 2000 rpm, followed by stirring and kneading for 1 minute. This resulted in Varnish X. The NV (non-volatile content) of the obtained Varnish X was 65.6% by mass. The average particle diameter D of the rubber particles was ５０ is the D of the magnetic powder A ５０ was measured in the same manner.

[0098] 5.17 g of varnish X, 20.00 g of magnetic powder A, and 0.06 g of a silane coupling agent ("KBM-573" manufactured by Shin-Etsu Silicones Co., Ltd., N-phenyl-3-aminopropyltrimethoxysilane) were weighed out. These were placed in a 50 ml ointment container as raw materials. All raw materials in the ointment container were stirred and kneaded using a rotary stirrer at a revolution speed of 2000 rpm for 45 seconds. Next, the raw materials in the ointment container were stirred using a medicine spoon. Furthermore, a liquid composition (paste) for forming a magnetic film was prepared by stirring twice using a rotary stirrer at a revolution speed of 2000 rpm for 45 seconds. The content of magnetic powder A based on the total mass of the nonvolatile content of the obtained paste was 85.3 mass%.

[0099] The paste obtained above was applied to a PET film substrate using a squeegee and dried for 20 minutes at 120° C. to form a magnetic film, thereby obtaining a laminate including a substrate and a magnetic film provided on the substrate.

[0100] Examples 2 to 6: Instead of MX-136, "MX-965" manufactured by Kaneka Corporation (a mixture of bisphenol-type liquid epoxy resin and rubber particles having a core-shell structure (core layer: silicone rubber, shell layer: acrylic resin) dispersed in the resin, rubber particle content: 25% by mass, average particle diameter D ５０ : 100 nm), "MX-217" manufactured by Kaneka Corporation (a mixture of phenol novolac liquid epoxy resin and rubber particles having a core-shell structure (core layer: butadiene rubber, shell layer: acrylic resin) dispersed in the resin, rubber particle content: 25 mass%, average particle diameter D of the rubber particles ５０: 100 nm), "LA-3320" manufactured by Kuraray Co., Ltd. (block copolymer having a block structure of polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate), "MD1658" manufactured by KRATON (block copolymer having a block structure of polystyrene-polybutylene-polyethylene-polystyrene), or "HTR-860" manufactured by Nagase ChemteX Corporation (acrylic rubber, solids content 12% by mass, weight average molecular weight 800,000, glass transition temperature 12 ° C.), respectively. The liquid compositions (pastes) and laminates of Examples 2 to 6 were obtained in the same manner as in Example 1, except that the rubber component was dispersed in the resin in the form of fine particles in MX-136, MX-965, and MX-217 used in Examples 1 to 3, whereas the rubber component was dispersed in the resin in the form of fine particles in LA-3320, MD1658, and HTR-860 used in Examples 4 to 6 were general rubber components, and the rubber component was amorphous (liquid).

[0101] Comparative Example 1 A liquid composition (paste) and a laminate of Comparative Example 1 were obtained in the same manner as in Example 1, except that the rubber component (MX-136) was not used and the blending amounts of the raw materials were adjusted so as to obtain a magnetic film made of a magnetic composition having the composition shown in Table 1.

[0102] <Evaluation 1> (Evaluation of Flexibility) The magnetic films of Examples 1 to 6 and Comparative Example 1 were wrapped around a rod with a diameter of 6 mm, and the magnetic films were visually inspected for cracks and peeling from the support. When neither cracks nor peeling was observed, the flexibility was evaluated as good (A), and when either cracks or peeling was observed, the flexibility was evaluated as poor (B). The evaluation results are shown in Table 1.

[0103] <Evaluation 2> Evaluations were made of the permeability of the magnetic layers prepared using the magnetic films of Examples 1 to 6 and Comparative Example 1, and the embeddability of the magnetic films. The procedures for evaluating permeability and embeddability are shown below, and the evaluation results are shown in Table 1.

[0104] (Evaluation of magnetic permeability) Magnetic films were laminated together using vacuum lamination to prepare a 1.1 mm thick magnetic film. 1 mm thick stainless steel plates were placed on all four sides of the magnetic film to surround it. Using a vacuum press (manual hydraulic vacuum heating press, 1A31, manufactured by Imoto Machinery Co., Ltd.), the magnetic film was pressurized and heated at 180°C and 2 MPa for 60 minutes under vacuum conditions to form and harden a 1 mm thick plate, thereby obtaining a magnetic layer. The magnetic layer was drilled into a ring-shaped sample with an outer diameter of 7 mm, an inner diameter of 3 mm, and a thickness of 1 mm. The relative permeability μ' of the magnetic layer at 1 GHz was measured using the ring-shaped sample and a network analyzer.

[0105] (Evaluation of Embeddability) A silicon wafer was cut with a dicer to form a groove 25 μm wide and 90 μm deep. A magnetic film (laminate) was placed on this wafer, and the wafer was pressurized and heated at 120 ° C and 0.5 MPa for 5 minutes using a vacuum laminator. The PET film support was peeled off from the wafer with the embedded magnetic film, and the magnetic film was cured by heating at 180 ° C for 60 minutes in a nitrogen atmosphere. The cured product was placed in an aluminum cup and fixed with a sample clip (Samplklip, manufactured by Buehler), and epoxy resin (Epomount, manufactured by Refine Tech Co., Ltd.) was poured into it and left at room temperature for 12 hours to harden the epoxy resin. A Refine Saw (RCA-005, manufactured by Refine Tech Co., Ltd.) equipped with a diamond cutting wheel (11-304, manufactured by Refine Tech Co., Ltd.) was used to cut the cast sample near the observation surface. The cross section was polished with abrasive paper to expose the observation surface, which was then smoothed with alumina powder to obtain an observation surface. The cross section of the sample was observed with a scanning electron microscope (SEM) (SU5000, manufactured by Hitachi High-Technologies Corporation). If the magnetic composition was filled to the bottom of the groove, the embeddability was evaluated as good (A), and if the magnetic composition was not filled to the bottom of the groove and a void was formed, the embeddability was evaluated as poor (B).

[0106] The numerical values ​​shown in the composition in the above table indicate the non-volatile content of each material.

[0107] 1...support, 2...magnetic film, 3...laminated body, 5...magnetic layer, 10...wiring board, 11...substrate, 12...wiring, 100...circuit member

Claims

1. A magnetic composition comprising a magnetic powder, a thermosetting component, and a rubber component, the rubber component including at least one selected from the group consisting of butadiene rubber, silicone rubber, styrene butadiene rubber, acrylic rubber, acrylic block copolymer, and styrene block copolymer.

2. The magnetic composition according to claim 1, wherein the content of said magnetic powder is 70 mass % or more based on the total mass of non-volatile matters in said magnetic composition.

3. The magnetic composition according to claim 1, which contains particles containing the rubber component.

4. The magnetic composition according to claim 3, wherein the average particle size of the particles containing the rubber component is 10 to 2,000 nm.

5. The magnetic composition according to claim 1, wherein the content of the rubber component is 0.05 to 10.0 mass % based on the total mass of non-volatile matters in the magnetic composition.

6. The magnetic composition of claim 1, wherein said thermosetting component comprises an epoxy group-containing compound and a phenolic hardener.

7. A magnetic film comprising the magnetic composition according to any one of claims 1 to 6.

8. A laminate comprising a support and the magnetic film according to claim 7 provided on the support.

9. A circuit component comprising a substrate having wiring provided on its surface, and a magnetic layer provided so as to fill gaps between the wiring of the substrate, the magnetic layer comprising a cured product of the magnetic composition according to any one of claims 1 to 6.

10. The circuit member of claim 9, wherein the wiring is a coil wiring of an inductor.

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