Magnetic paste, circuit member, and circuit member manufacturing method

Abstract

A magnetic paste containing (A) a magnetic powder, (B) a radically polymerizable compound, and (C) a thermal radical polymerization initiator.

Description

Magnetic paste, circuit component, and method for manufacturing the circuit component

[0001] The present disclosure relates to a magnetic paste, a circuit component, and a method for manufacturing a circuit component.

[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. In particular, there has been an increasing demand in recent years for materials containing magnetic powders and resins (see, for example, Patent Document 1).

[0003] JP 2014-127624 A

[0004] As a method for manufacturing circuit components, a method of filling minute gaps (e.g., gaps between wirings, through holes, blind holes, cavities, and trenches) in a substrate with a paste-like magnetic material (magnetic paste) has been investigated. However, as circuit components become smaller, the size of the gaps to which the magnetic paste is applied is also becoming smaller, and in order to sufficiently fill these gaps, the magnetic paste is required to have higher fluidity.

[0005] Therefore, one aspect of the present disclosure aims to provide a magnetic paste with improved fluidity, and other aspects of the present disclosure aim to provide a circuit component obtained using the magnetic paste and a method for manufacturing the same.

[0006] In some aspects, the present disclosure provides the following [1] to

[10] .

[0007] [1] A magnetic paste comprising: (A) a magnetic powder; (B) a radically polymerizable compound; and (C) a thermal radical polymerization initiator.

[0008] [2] The magnetic paste according to [1], wherein the component (B) includes a compound having a (meth)acryloyl group.

[0009] [3] The magnetic paste according to [1], wherein the component (B) includes a compound having one (meth)acryloyl group and a compound having two or more (meth)acryloyl groups.

[0010] [4] The magnetic paste according to [3], wherein the compound having two or more (meth)acryloyl groups includes a compound represented by the following formula (1): [In formula (1), R １１ and R １２ each independently represents a hydrogen atom or a methyl group, R １３ represents a divalent group having a poly(meth)acrylate chain.

[0011] [5] The magnetic paste according to any one of [1] to [4], wherein the component (B) is liquid at 25°C.

[0012] [6] The magnetic paste according to any one of [1] to [5], wherein the content of the component (A) is 40 to 90 volume % based on the total volume of the magnetic paste.

[0013] [7] The magnetic paste according to any one of [1] to [6], having a viscosity at 25°C of 1 to 600 Pa·s.

[0014] [8] The magnetic paste according to any one of [1] to [7], which is used to fill gaps between wirings, through holes, blind holes, cavities, or trenches provided in a substrate for circuit components.

[0015] [9] A circuit component comprising a substrate and a magnetic body that fills gaps between wirings, through holes, blind holes, cavities, or trenches provided in the substrate, wherein the magnetic body contains a cured product of the magnetic paste according to any one of [1] to [8].

[0016]

[10] A method for manufacturing a circuit component, comprising: a step of filling a gap between wirings, a through hole, a blind hole, a cavity, or a trench provided in a substrate with the magnetic paste according to any one of [1] to [8]; and a step of heating and hardening the magnetic paste.

[0017] According to one aspect of the present disclosure, it is possible to provide a magnetic paste having improved fluidity. Furthermore, according to other aspects of the present disclosure, it is possible to provide a circuit component obtained using the magnetic paste and a method for manufacturing the same.

[0018] 1A to 1C are schematic cross-sectional views illustrating an example of a method for manufacturing a circuit member according to an embodiment of the present disclosure.

[0019] In this specification, numerical ranges indicated using "to" indicate ranges that include 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 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 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 paste, the content of each component in the paste means the total amount of the multiple substances present in the paste, unless otherwise specified. In addition, in this specification, "(meth)acryloyl" means at least one of acryloyl and its corresponding methacryloyl. The same applies to other similar expressions such as "(meth)acrylate."

[0020] Hereinafter, exemplary embodiments of the present disclosure will be described, but the present disclosure is not limited to the following embodiments.

[0021] <Magnetic Paste> The magnetic paste of one embodiment contains (A) magnetic powder (hereinafter also referred to as "component (A)"), (B) radical polymerizable compound (hereinafter also referred to as "component (B)"), and (C) thermal radical polymerization initiator (hereinafter also referred to as "component (C)").

[0022] The magnetic paste contains a radical polymerizable compound and a thermal radical polymerization initiator as thermosetting components, and therefore has superior fluidity compared to conventional magnetic pastes (e.g., magnetic pastes containing epoxy resins). Therefore, the magnetic paste may be used to fill minute gaps (e.g., gaps between wirings, through-holes, non-through holes, cavities, and trenches) provided in substrates for circuit components, and in particular, may be used to fill through-holes, non-through holes, cavities, or trenches in which the use of organic solvents is strictly restricted.

[0023] Furthermore, since the fluidity of a magnetic paste tends to decrease as the amount of magnetic powder increases, conventional magnetic pastes require a reduced amount of magnetic powder to ensure sufficient fluidity, but the magnetic paste described above can maintain sufficient fluidity while allowing for a greater amount of magnetic powder to be blended than conventional pastes.As a result, the magnetic paste described above can achieve both sufficient fluidity and higher magnetic permeability.

[0024] [Component (A)] Component (A) (magnetic powder) is an aggregate of magnetic particles. The magnetic particles contain at least a magnetic component. The magnetic particles may contain one type of magnetic component alone, 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, and the content of the magnetic component based on the total mass of component (A) may be 50% 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 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 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, an iron alloy 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 metal compound containing the above metal element and an element other than the above metal element. Examples of the element other than the above metal element include 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 component or a ferromagnetic component. 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] In order to obtain a higher magnetic permeability, component (A) may contain at least one 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. In order to obtain an even higher magnetic permeability, component (A) 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 component (A) may be coated with a surface treatment agent. Examples of the surface treatment agent include inorganic oxides, phosphoric acid compounds, phosphate compounds, and inorganic surface treatment agents such as silane coupling agents, organic surface treatment agents such as montan wax, and cured resins. Coupling agents, which will be described later, can also be used as the surface treatment agent.

[0032] The surface of component (A) (e.g., magnetic powder containing an Fe-based alloy) may be entirely or partially coated with an insulating material. That is, component (A) may contain 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] Examples of insulating coated magnetic particles that can be used include "KUAMET9A4" (Fe-Si-B alloy, D50: 20 μm, with insulating coating) manufactured by Epson Atmix Corporation and "SAP-2C" (Fe-Si-B-P-Nb-Cr alloy, D50: 2.2 μm, with insulating coating) manufactured by Shinto Kogyo Co., Ltd. These insulating coated magnetic particles may be used in combination with magnetic particles that do not have an insulating coating, such as soft ferrite powder "BSN-125" (Ni-Zn alloy, D50: 10 μm, without insulating coating) manufactured by Toda Kogyo Co., Ltd.

[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 embeddability, 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 paste, and dense packing of the magnetic particles, the aspect ratio of the magnetic particles may be 1.0 to 3.0, 1.0 to 2.0, or 1.0 to 1.5.

[0035] From the viewpoint of the fluidity and magnetic permeability of the magnetic paste, the D50 of component (A) may be 1.1 μm or more, 1.2 μm or more, or 1.3 μm or more. From the viewpoint of dense packing of the magnetic particles, the D50 of component (A) may be 3.6 μm or less, 3.5 μm or less, or 3.4 μm or less. From these viewpoints, the D50 of component (A) may be 1.1 to 3.6 μm, 1.2 to 3.6 μm, 1.3 to 3.6 μm, 1.1 to 3.5 μm, 1.2 to 3.5 μm, 1.3 to 3.5 μm, 1.1 to 3.4 μm, 1.2 to 3.4 μm, or 1.3 to 3.4 μm. Note that D50 refers to the particle size at which the cumulative volume, from the smallest particle size in the volume-based particle size distribution of component (A), accounts for 50% of the total volume of component (A). The particle size distribution used to calculate D50 of the component (A) 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.

[0036] Component (A) may be a mixed powder obtained by combining multiple magnetic powders. The mixed powder may include, for example, a first magnetic powder having a D50 (50% cumulative particle size in a volume-based particle size distribution) of 0.5 to 8.0 μm and a second magnetic powder having a D50 (50% cumulative particle size in a volume-based particle size distribution) of 8.0 to 50.0 μm. The D50 of the first magnetic powder may be 1.0 to 5.0 μm or 1.5 to 4.5 μm. The D50 of the second magnetic powder may be 10.0 to 40.0 μm or 12.0 to 30.0 μm.

[0037] The amount of the first magnetic powder may be 5.0% by mass or more, 8.0% by mass or more, or 10.0% by mass or more, based on the total mass of the magnetic powder in the magnetic paste, from the viewpoints of dense particle packing and magnetic loss suppression. The amount of the first magnetic powder may be 95.0% by mass or less, 92.0% by mass or less, 90.0% by mass or less, 30.0% by mass or less, 28.0% by mass or less, or 25.0% by mass or less, based on the total mass of the magnetic powder in the magnetic paste, from the viewpoints of dense particle packing, paste viscosity, magnetic permeability of the cured product, and thermal expansion coefficient. From these viewpoints, the amount of the first magnetic powder may be 5.0 to 95.0 mass%, 5.0 to 92.0 mass%, 5.0 to 90.0 mass%, 8.0 to 95.0 mass%, 8.0 to 92.0 mass%, 8.0 to 90.0 mass%, 10.0 to 95.0 mass%, 10.0 to 92.0 mass%, or 10.0 to 90.0 mass%, based on the total mass of the magnetic powder in the magnetic paste. It may also be 5.0 to 30.0 mass%, 5.0 to 28.0 mass%, 5.0 to 25.0 mass%, 8.0 to 30.0 mass%, 8.0 to 28.0 mass%, 8.0 to 25.0 mass%, 10.0 to 30.0 mass%, 10.0 to 28.0 mass%, or 10.0 to 25.0 mass%.

[0038] The amount of the second magnetic powder may be 5.0% by mass or more, 10.0% by mass or more, 15.0% by mass or more, 70.0% by mass or more, 72.0% by mass or more, or 75.0% by mass or more, based on the total mass of the magnetic powder in the magnetic paste, from the viewpoints of the dense packing of the particles, the paste viscosity, the magnetic permeability of the cured product, and the thermal expansion coefficient. The amount of the second magnetic powder may be 95.0% by mass or less, 92.0% by mass or less, or 90.0% by mass or less, based on the total mass of the magnetic powder in the magnetic paste, from the viewpoints of the dense packing of the particles and magnetic loss. From these viewpoints, the amount of the second magnetic powder is, based on the total mass of the magnetic powder in the magnetic paste, 5.0 to 95.0 mass%, 5.0 to 92.0 mass%, 5.0 to 90.0 mass%, 10.0 to 95.0 mass%, 10.0 to 92.0 mass%, 10.0 to 90.0 mass%, 15.0 to 95.0 mass%, 15.0 to 92.0 mass%, 15.0 to 90.0 mass%, 70.0 to 95.0 mass%, 70.0 to 92.0 mass%, 70.0 to 90.0 mass%, 72.0 to 95.0 mass%, 72.0 to 92.0 mass%, 72.0 to 90.0 mass%, 75.0 to 95.0 mass%, 75.0 to 92.0 mass%, or 75.0 to 90.0 mass%.

[0039] The volume ratio of the first magnetic powder to the total volume of the first magnetic powder and the second magnetic powder ("volume of the first magnetic powder" / "total volume of the first magnetic powder and the second magnetic powder") may be 0.05 or more, 0.08 or more, or 0.10 or more, from the viewpoints of the dense packing of the particles, the paste viscosity, the magnetic permeability of the cured product, the thermal expansion coefficient, and the magnetic loss. The volume ratio of the first magnetic powder to the total volume of the first magnetic powder and the second magnetic powder may be 0.95 or less, 0.92 or less, 0.90 or less, 0.30 or less, 0.28 or less, or 0.25 or less, from the viewpoints of the dense packing of the particles, the paste viscosity, the magnetic permeability of the cured product, and the thermal expansion coefficient. From these viewpoints, the volume ratio of the first magnetic powder to the total volume of the first magnetic powder and the second magnetic powder may be 0.05 to 0.95, 0.05 to 0.92, 0.05 to 0.90, 0.08 to 0.95, 0.08 to 0.92, 0.08 to 0.90, 0.10 to 0.95, 0.10 to 0.92, or 0.10 to 0.90, or may be 0.05 to 0.30, 0.05 to 0.28, 0.05 to 0.25, 0.08 to 0.30, 0.08 to 0.28, 0.08 to 0.25, 0.10 to 0.30, 0.10 to 0.28, or 0.10 to 0.25.

[0040] The content of component (A) may be 40 volume % or more, 50 volume % or more, or 60 volume % or more, based on the total volume of the magnetic paste, from the viewpoint of obtaining high magnetic permeability. The content of component (A) may be 90 volume % or less, 85 volume % or less, or 80 volume % or less, based on the total volume of the magnetic paste, from the viewpoint of obtaining higher fluidity. From the above viewpoint, the content of component (A) may be 40 to 90 volume %, 40 to 85 volume %, 40 to 80 volume %, 50 to 90 volume %, 50 to 85 volume %, 50 to 80 volume %, 60 to 90 volume %, 60 to 85 volume %, or 60 to 80 volume %, based on the total volume of the magnetic paste.

[0041] [Component (B)] Component (B) (radical polymerizable compound) is a compound that polymerizes by radicals generated from component (C) (thermal radical polymerization initiator) by heat. Component (B) may be either a monomer or a polymer (or oligomer) obtained by polymerizing one or more monomers. As component (B), one type of compound may be used alone, or multiple types of compounds may be used in combination.

[0042] Component (B) is a compound having a functional group (radical polymerizable group) that reacts with a radical. Examples of the radical polymerizable group include a (meth)acryloyl group, a vinyl group, an allyl group, a styryl group, an alkenyl group, an alkenylene group, and a maleimide group. The number of radical polymerizable groups (number of functional groups) may be 1 to 10, 1 to 6, or 1 to 4.

[0043] As the (B) component, a compound having a (meth)acryloyl group (hereinafter also referred to as "component (B1)") may be used from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product (for example, adhesion, thermal properties, and mechanical properties). The (B1) component may be a compound having one (meth)acryloyl group (hereinafter also referred to as "component (B1-1)"), or may be a compound having two or more (meth)acryloyl groups (hereinafter also referred to as "component (B1-2)"). From the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product, the (B1-1) component and the (B1-2) component may be used in combination.

[0044] As the component (B1-1), an alkyl(meth)acrylate may be used from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product. The alkyl group (the portion other than the (meth)acryloyl group) may be linear, branched, or cyclic. The number of carbon atoms in the alkyl group may be 1 or more, 3 or more, 5 or more, or 6 or more, and may be 30 or less, 24 or less, 20 or less, 18 or less, 14 or less, or 12 or less. The number of carbon atoms in the alkyl group may be, for example, 1 to 30, 1 to 24, 3 to 18, 5 to 14, or 6 to 12, or 1 to 11, 1 to 8, 1 to 6, or 1 to 4, or 12 to 30, 12 to 28, 12 to 24, 12 to 22, 12 to 18, or 12 to 14.

[0045] The alkyl(meth)acrylate may have a cyclic alkyl group (cycloalkyl group) from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product. Examples of alkyl(meth)acrylates having a cyclic alkyl group include cyclohexyl(meth)acrylate, 3,3,5-trimethylcyclohexyl(meth)acrylate, isobornyl(meth)acrylate, terpene(meth)acrylate, and dicyclopentanyl(meth)acrylate.

[0046] The content of alkyl (meth)acrylate may be 0 to 80 mass % based on the total mass of component (B), and from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product, it may be 5 to 80 mass %, 5 to 70 mass %, or 10 to 60 mass %.

[0047] As the (B1-1) component, a compound represented by the following formula (I) (hereinafter also referred to as an "acrylamide-based compound") may be used in order to achieve a better balance between the fluidity of the magnetic paste and the properties of the cured product.

[0048] In formula (I), R １ and R ２ R each independently represents a hydrogen atom or a monovalent organic group, and may be bonded to each other to form a ring. ３ represents a hydrogen atom or a methyl group.

[0049] R １ and R ２ The monovalent organic group represented by the formula (I) may be a group containing carbon atoms, hydrogen atoms, oxygen atoms, sulfur atoms, etc., may be a group containing only carbon atoms and hydrogen atoms, or may be a group containing only carbon atoms, hydrogen atoms, and oxygen atoms. The monovalent organic group may be, for example, a monovalent hydrocarbon group such as an alkyl group. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group.

[0050] R １ and R ２ The ring formed by may be a 5-membered ring, a 6-membered ring, or a 7-membered ring. １ and R ２ and a group represented by the formula (I) and may contain, in addition to a nitrogen atom, a carbon atom, a hydrogen atom, an oxygen atom, a sulfur atom, etc., or may contain only a nitrogen atom, a carbon atom, a hydrogen atom, and an oxygen atom.

[0051] Specific examples of the acrylamide compound include dimethylacrylamide, diethylacrylamide, diisopropylacrylamide, N-(meth)acryloylmorpholine, N-acryloylthiomorpholine, N-acryloyloxazoline, N-acryloylthiazolidine, N-acryloylimidazolidine, N-(meth)acryloylpiperazine, N-vinylpyrrolidone, and N-vinylcaprolactam.

[0052] The content of the acrylamide-based compound may be 0 to 80 mass % based on the total mass of component (B), and from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product, it may also be 5 to 80 mass %, 5 to 70 mass %, or 10 to 60 mass %.

[0053] Hydroxyalkyl (meth)acrylates may be used as component (B1-1) from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product. Hydroxyalkyl (meth)acrylates are compounds in which one or more hydrogen atoms in the above-mentioned alkyl (meth)acrylates are substituted with hydroxy groups. Examples of hydroxyalkyl (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.

[0054] The content of the hydroxyalkyl (meth)acrylate may be 0 to 80 mass % based on the total mass of component (B), and from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product, it may be 5 to 80 mass %, 5 to 70 mass %, or 10 to 60 mass %.

[0055] As the component (B1-1), one type of compound may be used alone, or multiple types of compounds may be used in combination. From the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product, an alkyl(meth)acrylate may be used in combination with at least one selected from the group consisting of an acrylamide compound and a hydroxyalkyl(meth)acrylate. The total amount of these compounds may be 90 to 100 mass%, 95 to 100 mass%, or 99 to 100 mass%, based on the total mass of the component (B1-1).

[0056] Compounds other than those listed above may be used as the component (B1-1), and the content of such compounds may be 40% by mass or less, 30% by mass or less, or 20% by mass or less, based on the total mass of the component (B1-1).

[0057] The content of the (B1-1) component may be 20 to 99 mass %, 30 to 95 mass %, or 40 to 90 mass % based on the total mass of the (B) component, from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product.

[0058] As the component (B1-2), a compound represented by the following formula (1) may be used from the viewpoint of improving the thermal properties and mechanical properties of the cured product.

[0059] In formula (1), R １１ and R １２ each independently represents a hydrogen atom or a methyl group, R １３ represents a divalent group having a poly(meth)acrylate chain.

[0060] The poly(meth)acrylate chain contains a structural unit represented by the following formula (1a):

[0061] In formula (1a), R １４ represents a hydrogen atom or a monovalent organic group, R １５ represents a hydrogen atom or a methyl group.

[0062] R １４ The monovalent organic group represented by the formula (I) may be, for example, a hydrocarbon group, an organic group having an oxygen atom, or an organic group having a nitrogen atom.

[0063] The hydrocarbon group may be linear or may have a ring (for example, an aromatic ring). The number of carbon atoms in the hydrocarbon group may be, for example, 1 or more and 18 or less. Examples of the hydrocarbon group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, an n-octyl group, a 2-ethylhexyl group, a 2-propylheptyl group, a nonyl group, a decyl group, an isodecyl group, a dodecyl group, an octadecyl group, a phenyl group, a toluyl group, and a benzyl group.

[0064] Examples of organic groups having an oxygen atom include groups having an alkoxy group, groups having a hydroxyl group, groups having a carboxyl group, and groups having a glycidyl group. Examples of groups having an alkoxy group include a 2-methoxyethyl group and a 3-methoxybutyl group. Examples of groups having a hydroxyl group include a 2-hydroxyethyl group, a 2-hydroxypropyl group, and a 4-hydroxybutyl group. Examples of groups having a carboxyl group include a carboxyl group. Examples of groups having a glycidyl group include a glycidyl group.

[0065] Examples of the organic group having a nitrogen atom include a group having an amino group or a nitrile group. An example of the group having an amino group is a 2-aminoethyl group. An example of the group having a nitrile group is a nitrile group.

[0066] R １４ The monovalent organic group represented by the formula (I) may be a group having a polar group, or a group having a hydroxyl group or a carboxyl group, from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product.

[0067] The compound represented by formula (1) may be a compound represented by the following formula (1-1).

[0068] In formula (1-1), R １１ and R １２ is R in formula (1) １１ and R １２ and R １４ and R １５ is R in formula (1a) １４ and R １５ and n is an integer of 2 or more (for example, 2 to 1000).

[0069] The viscosity of the compound represented by formula (1) at 23°C is, for example, 5 to 1000 Pa·s, and may be 10 Pa·s or more, 15 Pa·s or more, 20 Pa·s or more, 25 Pa·s or more, 30 Pa·s or more, or 35 Pa·s or more, and may be 800 Pa·s or less, 700 Pa·s or less, 600 Pa·s or less, or 550 Pa·s or less.

[0070] The viscosity in this specification refers to a value measured in accordance with JIS Z8803, and specifically refers to a value measured using an E-type viscometer (for example, PE-80L manufactured by Toki Sangyo Co., Ltd.). The viscometer can be calibrated in accordance with JIS Z8809-JS14000.

[0071] The glass transition temperature (Tg) of the compound represented by formula (1) is, for example, −60 to 0° C., and may be −50° C. or higher, or −40° C. or higher, and may be −10° C. or lower, or −30° C. or lower. The glass transition temperature (Tg) of the compound represented by formula (1) may be −60 to −10° C., −60 to −30° C., −50 to 0° C., −50 to −10° C., −50 to −30° C., −40 to 0° C., −40 to −10° C., or −40 to −30° C. The glass transition temperature means a value measured by differential scanning calorimetry.

[0072] From the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product, the content of the compound represented by formula (1) may be 0 to 70 mass %, 5 to 60 mass %, or 10 to 50 mass % based on the total mass of component (B). The content of the compound represented by formula (1-1) may be within the above ranges.

[0073] As the component (B1-2), one type of compound may be used alone, or multiple types of compounds may be used in combination. As the component (B1-2), compounds other than those mentioned above may be used, and the content of such compounds may be 10% by mass or less, 5% by mass or less, or 1% by mass or less, based on the total mass of the component (B1-2).

[0074] The content of the (B1-2) component may be 0 to 70 mass %, 5 to 60 mass %, or 10 to 50 mass % based on the total mass of the (B) component, from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product.

[0075] The mass ratio of the (B1-2) component to the (B1-1) component (content of the (B1-2) component / content of the (B1-1) component) may be 0.02 to 4.0, 0.1 to 1.5, or 0.2 to 0.7, from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product.

[0076] The content of the (B1) component (the sum of the content of the (B1-1) component and the content of the (B1-2) component) may be 60 to 100 mass %, 70 to 100 mass %, or 80 to 100 mass % based on the total mass of the (B) component, from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product.

[0077] Component (B) may contain a compound (hereinafter also referred to as "polymer compound") having a weight-average molecular weight of 3,000 or more from the viewpoint of improving the properties of the cured product. The weight-average molecular weight of the polymer compound may be 4,000 or more, 5,000 or more, 6,000 or more, 7,000 or more, 8,000 or more, 9,000 or more, 10,000 or more, 11,000 or more, 12,000 or more, or 13,000 or more from the viewpoint of suppressing warping of the cured product and improving the strength of the cured product. The weight-average molecular weight of the polymer compound may be 100,000 or less, 80,000 or less, 60,000 or less, 34,000 or less, 31,000 or less, or 28,000 or less from the viewpoint of improving the fluidity of the magnetic paste. From the above viewpoint, the weight-average molecular weight of the polymer compound may be, for example, 3,000 to 100,000.

[0078] The polymer compound may be the above-mentioned component (B1). The polymer compound may be either component (B1-1) or component (B1-2), but from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product, it may be a compound represented by formula (1). That is, the weight-average molecular weight of the compound represented by formula (1) may be in the above-mentioned range. n in formula (1-1) may be an integer such that the weight-average molecular weight of the compound represented by formula (1) falls within the above-mentioned range.

[0079] The weight average molecular weight in this specification refers to a value measured using gel permeation chromatography (GPC) under the following conditions and determined using polystyrene as a standard substance: Measuring instrument: HLC-8320GPC (product name, manufactured by Tosoh Corporation) Analytical column: TSKgel SuperMultipore HZ-H (three columns connected) (product name, manufactured by Tosoh Corporation) Guard column: TSKguardcolumn SuperMP(HZ)-H (product name, manufactured by Tosoh Corporation) Eluent: THF Measurement temperature: 25°C

[0080] The content of the polymer compound may be 0 to 70 mass %, 5 to 60 mass %, or 10 to 50 mass %, based on the total mass of component (B), from the viewpoint of achieving a better balance between the fluidity of the magnetic paste and the properties of the cured product.

[0081] Component (B) may be liquid at 25° C. Here, "liquid at 25° C." means that the viscosity at 25° C. measured with an E-type viscometer is 600 Pa s or less, and when component (B) contains multiple compounds, it means that a mixture consisting of all of the compounds corresponding to component (B) is liquid at 25° C.

[0082] The content of the (B) component may be 1.0% by mass or more, 1.5% by mass or more, or 2.0% by mass or more, based on the total mass of the nonvolatile content in the magnetic paste, from the viewpoint of obtaining higher fluidity. The content of the (B) component may be 20% by mass or less, 15% by mass or less, or 10% by mass or less, based on the total mass of the nonvolatile content in the magnetic paste, from the viewpoint of obtaining high magnetic permeability. From the above viewpoint, the content of the (B) component may be 1.0 to 20% by mass, 1.0 to 15% by mass, 1.0 to 10% by mass, 1.5 to 20% by mass, 1.5 to 15% by mass, 1.5 to 10% by mass, 2.0 to 20% by mass, 2.0 to 15% by mass, or 2.0 to 10% by mass, based on the total mass of the nonvolatile content in the magnetic paste. The nonvolatile content in the magnetic paste refers to the components contained in the magnetic paste other than the volatile components. The volatile component refers to a component that shows a mass loss of 20% by mass or more when heated at 180°C for 60 minutes in the presence of a thermal radical polymerization initiator and has a boiling point of 300°C or lower.

[0083] [Component (C)] Examples of component (C) (thermal radical polymerization initiator) include azo compounds and organic peroxides. Examples of azo compounds include azobisisobutyronitrile, azobis-4-methoxy-2,4-dimethylvaleronitrile, azobiscyclohexanone-1-carbonitrile, and azodibenzoyl. Examples of organic peroxides include benzoyl peroxide, lauroyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-2-ethylhexanoate, 1,1-t-butylperoxy-3,3,5-trimethylcyclohexane, and t-butylperoxyisopropyl carbonate. As component (C), these compounds may be used alone or in combination of two or more.

[0084] From the viewpoint of allowing the polymerization of the component (B) to proceed smoothly, the content of the component (C) may be 0.01 parts by mass or more, 0.05 parts by mass or more, 0.1 parts by mass or more, or 0.5 parts by mass or more, per 100 parts by mass of the component (B). From the viewpoint of allowing the polymerization to proceed smoothly, the content of the component (C) may be 10 parts by mass or less, 5 parts by mass or less, or 3 parts by mass or less, per 100 parts by mass of the component (B). From the above viewpoint, the content of the component (C) may be 0.01 to 10 parts by mass, 0.05 to 5 parts by mass, 0.1 to 3 parts by mass, or 0.5 to 3 parts by mass, per 100 parts by mass of the component (B).

[0085] [Component (D)] The magnetic paste may further contain an antioxidant (hereinafter also referred to as “component (D)”). Examples of the antioxidant include phenol-based antioxidants, benzophenone-based antioxidants, benzoate-based antioxidants, hindered amine-based antioxidants, and benzotriazole-based antioxidants.

[0086] As the antioxidant, a phenolic antioxidant may be used from the viewpoints of heat resistance and low volatility. The phenolic antioxidant has, for example, a hindered phenol structure (hindered phenol ring). The hindered phenol structure (hindered phenol ring) may be, for example, a structure in which t-butyl groups are bonded to one or both of the ortho positions relative to the hydroxyl group on the phenol ring. The phenolic antioxidant has one or more such hindered phenol rings, and may also have two or more, three or more, or four or more such hindered phenol rings.

[0087] Examples of phenolic antioxidants include 2-t-butyl-4-methoxyphenol, 3-t-butyl-4-methoxyphenol, 2,6-di-t-butyl-4-ethylphenol, 2,2'-methylene-bis(4-methyl-6-t-butylphenol), 4,4'-thiobis-(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, and tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane.

[0088] The content of the antioxidant may be 0.01 to 10 parts by mass, 0.05 to 8 parts by mass, or 0.1 to 5 parts by mass relative to 100 parts by mass of component (B) in the magnetic paste.

[0089] [Other Components] The magnetic paste may further contain components (other components) other than the components described above. Examples of other components include thermoplastic resins, coupling agents, flame retardants, dispersants, viscosity modifiers, lubricants, etc.

[0090] 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 0.01 to 1.0 mass % based on the total mass of the nonvolatile content in the magnetic paste.

[0091] 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 paste to the substrate. Therefore, the use of a coupling agent tends to further improve the filling property and also tends to produce a magnetic material that is less susceptible to cracking. 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. Among these, a silane coupling agent may be used from the viewpoint of easily achieving the above-mentioned effect.

[0092] The silane coupling agent has the formula: -SiR １ ｎ (OR ２ ) ３－ｎ It is an organic compound having a hydrolyzable silyl group represented by the formula: １ and R ２ each independently represents a hydrocarbon group, and n represents an integer of 0 to 2. １ and R ２ If there are multiple R １ and R ２ may be the same or different. The hydrocarbon group is, for example, an alkyl group having 1 to 20 carbon atoms.

[0093] The silane coupling agent may further have, in addition to the hydrolyzable silyl group, a reactive functional group such as an epoxy group, a mercapto group, a (meth)acryloyl group, a styryl group, a vinyl group, an acid anhydride group, a ureido group, etc., and / or an organic functional group such as an alkyl group, an aryl group, etc. Note that a silane coupling agent having a radical polymerizable group also falls under the category of component (B).

[0094] The silane coupling agent may be, for example, at least one selected from the group consisting of epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, acid anhydride silane, methacryl silane, styryl silane, and vinyl silane.

[0095] Specific examples of the silane coupling agent include N-phenyl-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, octyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 8-methacryloxyoctyltrimethoxysilane, p-styryltrimethoxysilane, vinyltrimethoxysilane, and 7-octenyltrimethoxysilane.

[0096] From the viewpoints of adhesion and dispersibility, the content of the coupling agent may be 0.01% by mass or more, 0.05% by mass or more, or 0.1% by mass or more, based on the total mass of the nonvolatile content in the magnetic paste. From the viewpoint of magnetic permeability, the content of the coupling agent may be 1.0% by mass or less, 0.9% by mass or less, or 0.8% by mass or less, based on the total mass of the nonvolatile content in the magnetic paste. From these viewpoints, the content of the coupling agent may be 0.01 to 1.0% by mass, 0.05 to 0.9% by mass, or 0.1 to 0.8% by mass, based on the total mass of the nonvolatile content in the magnetic paste.

[0097] The flame retardant contributes to the environmental safety, recyclability, and cost reduction of the magnetic paste. 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 nonvolatile matter in the magnetic paste.

[0098] The dispersant contributes to a higher filling rate of the magnetic powder, a lower viscosity, improved printability, etc. The dispersant may be, for example, at least one selected from the group consisting of polyester, polyether, polyoxyalkylene, phosphoric acid, phosphate ester, alkylammonium salt, polyacrylic acid, and sulfonic acid. The content of the dispersant may be 0.01 to 1.0 mass%, 0.02 to 0.9 mass%, or 0.03 to 0.8 mass%, based on the total mass of the nonvolatile content in the magnetic paste.

[0099] The magnetic paste may contain a compound having one or more epoxy groups in its molecule (hereinafter referred to as an "epoxy group-containing compound") to the extent that it does not impair the effects of the present disclosure, but the content of the epoxy group-containing compound is, for example, 1 mass % or less based on the total mass of the non-volatile matter in the magnetic paste.

[0100] The magnetic paste may contain an organic solvent, if necessary. The organic solvent is not particularly limited. For example, an organic solvent capable of dissolving the thermosetting 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, ethyl acetate, butyl acetate, toluene, 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 250°C or lower.

[0101] On the other hand, if the magnetic paste contains an organic solvent, a drying process is required after filling fine gaps such as through-holes with the magnetic paste, resulting in environmental impact due to volatile components. Furthermore, organic solvents with boiling points lower than the curing temperature may rapidly volatilize upon heating, resulting in the formation of voids in the cured magnetic paste. Furthermore, organic solvents with boiling points higher than the curing temperature may be less likely to volatilize upon heating and may remain in the paste, degrading the properties of the cured product. For example, the presence of voids in the cured product can lead to a decrease in properties such as mechanical strength and magnetic properties. Furthermore, residual organic solvents in the cured product can facilitate the migration of ionic components and other components in the cured product, resulting in a decrease in insulation properties such as insulation resistance and insulation reliability. These phenomena are particularly pronounced when filling through-holes, blind holes, cavities, and trenches.

[0102] From these viewpoints, particularly when the magnetic paste is used for filling through-holes, blind holes, cavities, or trenches, the content of the organic solvent 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 paste. The magnetic paste used for the above-mentioned purposes may be a so-called "solvent-free magnetic paste" that does not substantially contain an organic solvent. In this specification, "substantially does not contain an organic solvent" means that no organic solvent has been intentionally added to the magnetic paste. The magnetic paste that does not substantially contain an organic solvent may contain, for example, an organic solvent that was used during the production of the resin and remains in the resin.

[0103] From the same viewpoint as above, the magnetic paste used to fill fine gaps (particularly through-holes, blind holes, cavities, and trenches) may have a thermal weight loss rate of 5% or less when cured by heat treatment at 180°C. The thermal weight loss rate may be 3% or less, 2% or less, or 0%. The thermal weight loss rate can be calculated from measurements using a thermogravimetric differential thermal analyzer (TG-DTA). When the thermal weight loss rate of the magnetic paste is 5% or less, it becomes easy to fill the gaps with a cured product that has excellent desired properties such as insulation.

[0104] When the magnetic paste is used to fill spaces between wirings, the content of the organic solvent may be 0.01 to 10 mass %, 0.1 to 8 mass %, or 0.5 to 5 mass % based on the total mass of the magnetic paste.

[0105] The viscosity of the magnetic paste may be 1 Pa·s or more, or may be 10 Pa·s or more, or 100 Pa·s or more. By adjusting the viscosity to 1 Pa·s or more, settling of the magnetic powder in the magnetic paste is suppressed, and the decrease in filling ability over time after stirring the magnetic paste can be easily improved. On the other hand, the viscosity of the magnetic paste may be 600 Pa·s or less, or may be 400 Pa·s or less, or 200 Pa·s or less. By adjusting the viscosity to 600 Pa·s or less, the magnetic paste becomes more likely to have fluidity, making it easier to obtain better filling ability. From these viewpoints, the viscosity of the magnetic paste may be 1 to 600 Pa s, 1 to 400 Pa s, 1 to 200 Pa s, 10 to 600 Pa s, 10 to 400 Pa s, 10 to 200 Pa s, 100 to 600 Pa s, 100 to 400 Pa s, or 100 to 200 Pa s. The above viscosities are measured at 25°C by the method described in the examples.

[0106] The viscosity of the magnetic paste can be adjusted by the types and mixing ratios of the ingredients.

[0107] The magnetic paste of the above embodiment can be prepared, for example, by uniformly stirring and kneading the components (A), (B), and (C), and optionally other components. The method of stirring and kneading is not particularly limited, and for example, a stirring blade, a rotary / revolution type mixer, a planetary mixer, a roll mill, a disk mill, or a ball mill can be used.

[0108] <Circuit Component> Another embodiment of the present disclosure is a circuit component including a substrate and a magnetic body that fills gaps between wirings, through holes, blind holes, cavities, or trenches provided in the substrate, wherein the magnetic body includes a cured product of the magnetic paste of the above embodiment.

[0109] The circuit component of the embodiment may be, for example, an inductor, or an intermediate component for manufacturing an inductor.

[0110] <Method for manufacturing circuit component> Another embodiment of the present disclosure is a method for manufacturing a circuit component, including a step of filling gaps between wirings, through holes, blind holes, cavities, or trenches provided in a substrate with the magnetic paste of the above embodiment, and a step of heating and hardening the magnetic paste.

[0111] The above method can obtain the circuit component of the above embodiment. Furthermore, since the above method uses the magnetic paste of the above embodiment, the above method can obtain a circuit component in which gaps between wirings, through holes, blind holes, cavities, or trenches are satisfactorily filled with the magnetic material.

[0112] The circuit component and the manufacturing method thereof according to the above embodiment will be described in more detail below with reference to FIG. 1, taking a method of filling through holes as an example.

[0113] 1 is a schematic cross-sectional view showing a method for manufacturing a circuit member 10 according to one embodiment. The method for manufacturing a circuit member 10 according to one embodiment includes at least a step of filling a through-hole 1 a of a substrate 1 with a magnetic paste 2 (hereinafter referred to as “step (1)”), and a step of heating and hardening the magnetic paste 2 (hereinafter referred to as “step (2)”).

[0114] [Step (1)] In step (1), a magnetic paste 2 is filled into the through holes 1a of a substrate 1 having the through holes 1a (see (a) of FIG. 1). The substrate 1 may be a substrate having a metal layer (e.g., a copper layer) on the surface of an insulating substrate such as a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, or a thermosetting polyphenylene ether substrate. Although not shown, the metal layer may be a single layer or multiple layers. The metal layer may be formed on the inner wall of the through hole constituting the through hole 1a. The substrate 1 usually has multiple through holes 1a, but the number of through holes 1a is not particularly limited.

[0115] The filling of the magnetic paste 2 may be carried out by printing the magnetic paste by a known printing method (e.g., screen printing) using a squeegee, vacuum printing machine, etc., or by a method such as roll coating, inkjet printing, or dispenser. The filling may also be carried out by pressing a film coated with the magnetic paste onto a substrate having through holes using a vacuum press, vacuum lamination, or the like.

[0116] In step (1), a substrate 1 that has been prepared in advance may be used, or a substrate 1 that has through-holes 1 a may be prepared by preparing a substrate that does not have through-holes 1 a and forming through-holes in the substrate by drilling, laser irradiation, plasma irradiation, etc. After the through-holes are formed, a metal layer can be formed on the inner walls of the through-holes by performing a roughening treatment (plasma treatment, wet treatment using a swelling liquid, an oxidizing agent, etc.) and a plating treatment.

[0117] [Step (2)] In step (2), the magnetic paste 2 is heated and cured. This forms a magnetic body 3 containing the cured magnetic paste, and a circuit member 10 is obtained (see FIG. 1(b)). The heating temperature is, for example, 80°C or higher, and may be 90 to 240°C, 100 to 220°C, or 110 to 200°C. The heating time may be, for example, 1 to 180 minutes, 5 to 120 minutes, or 10 to 60 minutes. The heating may be performed in multiple stages, including preheating. For example, preheating at 80°C for 60 minutes may be followed by heating at 150°C for 30 minutes. The heating may be performed so that the degree of curing of the magnetic paste is 80% or higher. The degree of curing after heating may be 85% or higher, or 90% or higher. The degree of curing can be measured, for example, using a differential scanning calorimeter.

[0118] Although one embodiment of the method for manufacturing a circuit component has been described above, the method for manufacturing a circuit component of the present disclosure is not limited to the above method.

[0119] For example, in step (1), if a portion of the magnetic paste protrudes from the surface of the substrate 1, a step of removing the excess magnetic paste may be carried out. This step may be carried out after step (2). The removal method is not particularly limited, but the excess magnetic material may be removed, for example, by polishing the magnetic material 3 by buff polishing, belt polishing, or the like.

[0120] The method may further include, for example, a step of cleaning cutting residue adhering to the through-holes formed in the magnetic body with water or air, a step of roughening the magnetic body 3 (desmearing step), and a step of forming a conductor layer on the magnetic body 3. The conductor layer can be formed, for example, by a method in which after electroless plating, a resist corresponding to the wiring pattern is formed, electrolytic copper plating is performed, and the resist is then stripped and flash etching is performed.

[0121] 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.

[0122] In the examples and comparative examples, the following components were used.

[0123] (A) Magnetic powder A1: "KUAMET 9A4-II" manufactured by Epson Atmix Corporation (trade name, iron amorphous alloy powder, D50 = 25.0 μm) A2: "AW2-08" manufactured by Epson Atmix Corporation (trade name, Fe-Si-B-C-Cr alloy powder, D50 = 3.3 μm) A3: "M001" manufactured by Powder Tech Co., Ltd. (trade name, manganese ferrite powder, D50 = 0.1 μm)

[0124] (B) Radical polymerizable compounds B1: "IBXA" (trade name, isobornyl acrylate, liquid at 25°C) manufactured by Osaka Organic Chemical Industry Ltd. B2: "4HBA" (trade name, 4-hydroxybutyl acrylate, liquid at 25°C) manufactured by Osaka Organic Chemical Industry Ltd. B3: "ACMO" (trade name, N-acryloylmorpholine, liquid at 25°C) manufactured by KJ Chemicals Co., Ltd. B4: "RC200C" (trade name, compound represented by the above formula (1-1) (R in formula (1-1)) manufactured by Kaneka Corporation １１ and R １２is a hydrogen atom or a methyl group, and R １４ is a group having a polar group, and R １５ is a hydrogen atom), weight average molecular weight: 18,000, viscosity at 23°C: 530 Pa s, Tg: -39°C, liquid at 25°C)

[0125] (C) Thermal radical polymerization initiator C1: NOF Corporation's "Perbutyl O" (t-butylperoxy-2-ethylhexanoate)

[0126] (D) Antioxidant D1: "Irganox 1010" (trade name, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane) manufactured by BASF Japan Ltd.

[0127] Dispersant: BYK's "DISPERBYK-111" (product name) and BYK's "DISPERBYK-2152" (product name)

[0128] Coupling agents: "KBM-5803" (product name: 8-methacryloxyoctyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.; "KBM-573" (product name: N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd.

[0129] Preparation Examples 1 and 2 Component (B) (radical polymerizable compound), component (C) (thermally radical polymerizable compound), and component (D) (antioxidant) were weighed out in the blending ratio (unit: parts by mass) shown in Table 1 and placed in an ointment container. The raw materials in the ointment container were stirred and kneaded for 1 minute at a revolution speed of 2000 rpm using a rotary and revolving mixer ("ARE-500" manufactured by Thinky Corporation). Next, the raw materials in the ointment container were further stirred using a medicine spoon, and then again stirred and kneaded for 1 minute at a revolution speed of 2000 rpm using the rotary and revolving mixer, thereby preparing Compositions A and B, respectively.

[0130]

[0131] Preparation Example 3 70 parts by mass of the liquid epoxy resin "YDF-8170C" manufactured by Nippon Steel Chemical Co., Ltd., 30 parts by mass of the liquid epoxy resin "ADEKA GLYCIROL ED-503G" manufactured by ADEKA Corporation, and 30 parts by mass of the curing agent "jER Cure WA" (liquid aromatic amine) manufactured by Mitsubishi Chemical Corporation were weighed and placed in an ointment container. All raw materials in the ointment container were stirred and kneaded using a rotary mixer ("ARE-500" manufactured by Thinky Corporation) at a revolution speed of 2000 rpm for 1 minute. Next, the raw materials in the ointment container were further stirred using a medicine spoon, and then again stirred and kneaded using the rotary mixer at a revolution speed of 2000 rpm for 1 minute to prepare Composition C.

[0132] Example 1 (Preparation of Magnetic Paste) Component (A), Composition A prepared above, a dispersant, and a coupling agent were weighed out in the blending ratio (unit: parts by mass) shown in Table 2 and placed in an ointment container. The volume ratio of magnetic powder A1 to magnetic powder A2 was 79% by volume for magnetic powder A1 and 21% by volume for magnetic powder A2. The raw materials in the ointment container were stirred using a medicine spoon, and then stirred and kneaded for 45 seconds at a revolution speed of 2000 rpm using a rotary and revolutionary mixer ("ARE-500" manufactured by Thinky Corporation). Next, the raw materials in the ointment container were further stirred using a medicine spoon, and then stirred and kneaded for 45 seconds at a revolution speed of 2000 rpm using a rotary and revolutionary mixer. This process was repeated twice to obtain the magnetic paste of Example 1.

[0133] Example 2 A magnetic paste of Example 2 was obtained in the same manner as in Example 1, except that Composition B was used instead of Composition A.

[0134] <Examples 3 to 7> Magnetic pastes of Examples 3 to 7 were obtained in the same manner as Example 2, except that the component (A), the type of dispersant, and / or the compounding ratio of each component was changed as shown in Table 2. The volume ratio of magnetic powder A2 to magnetic powder A3 in Example 6 was 83 vol % for magnetic powder A2 and 17 vol % for magnetic powder A3.

[0135] <Comparative Example 1> A magnetic paste of Comparative Example 1 was obtained in the same manner as in Example 1, except that Composition C was used in place of Composition A in the compounding ratio shown in Table 2 and the type of coupling agent was changed as shown in Table 2.

[0136] <Evaluation> (Evaluation of Magnetic Permeability) The magnetic paste was applied to a PET film support using a squeegee and dried at 120°C for 20 minutes to form a magnetic film. Two 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. A ring-shaped sample with an outer diameter of 7 mm, an inner diameter of 3 mm, and a thickness of 1 mm was formed by drilling. The relative magnetic permeability μ' at 20 MHz was measured using a network analyzer.

[0137] (Evaluation of fluidity) The fluidity of the magnetic paste was evaluated based on the viscosity of the obtained magnetic paste. The viscosity was measured using a TV-33 viscometer manufactured by Toki Sangyo Co., Ltd. under the conditions of temperature: 25°C, rotor: SPP, and rotation speed: 2.5 rpm. The results are shown in Table 2. When the viscosity of the magnetic paste was 600 Pa s or less, the fluidity was evaluated as good. In addition, the presence or absence of an improvement effect on fluidity was evaluated based on Comparative Example 1.

[0138]

[0139] REFERENCE SIGNS LIST 1...substrate, 1a...through hole, 2...magnetic paste, 3...magnetic body, 10...circuit member

Claims

1. A magnetic paste containing (A) a magnetic powder, (B) a radical polymerizable compound, and (C) a thermal radical polymerization initiator.

2. The magnetic paste according to claim 1, wherein component (B) includes a compound having a (meth)acryloyl group.

3. The magnetic paste according to claim 1, wherein component (B) includes a compound having one (meth)acryloyl group and a compound having two or more (meth)acryloyl groups.

4. The magnetic paste according to claim 3, wherein the compound having two or more (meth)acryloyl groups includes a compound represented by the following formula (1): [In formula (1), R １１ and R １２ each independently represents a hydrogen atom or a methyl group, R １３ represents a divalent group having a poly(meth)acrylate chain.

5. The magnetic paste according to claim 1, wherein component (B) is liquid at 25°C.

6. The magnetic paste according to claim 1, wherein the content of component (A) is 40 to 90 volume % based on the total volume of the magnetic paste.

7. The magnetic paste according to claim 1, having a viscosity at 25°C of 1 to 600 Pa·s.

8. The magnetic paste according to claim 1, which is used to fill gaps between wirings, through holes, blind holes, cavities or trenches provided in a substrate for circuit components.

9. A circuit component comprising a substrate and a magnetic body that fills gaps between wirings, through holes, blind holes, cavities, or trenches provided in the substrate, wherein the magnetic body comprises a hardened product of the magnetic paste according to any one of claims 1 to 8.

10. A method for manufacturing a circuit component, comprising the steps of: filling gaps between wirings, through holes, blind holes, cavities, or trenches provided in a substrate with the magnetic paste according to any one of claims 1 to 8; and heating and hardening the magnetic paste.

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