Magnetic board manufacturing method and magnetic board

Abstract

This method for manufacturing a magnetic board, which comprises a magnetic layer and a conductor layer formed on a surface of the magnetic layer, includes a step (EP) of forming the conductor layer on the surface of the magnetic layer by means of electroplating. The magnetic layer includes a curing material that is a resin composition including (A) magnetic powder and (B) thermosetting resin. The (A) magnetic powder includes (A-1) alloy powder the mass percentage of which is equal to or greater than 30% relative to the (A) magnetic powder the mass percentage of which is 100%.

Description

Magnetic substrate manufacturing method and magnetic substrate

[0001] The present invention relates to a method for manufacturing a magnetic substrate, and to a magnetic substrate.

[0002] Substrates with inductors are mounted in large numbers on information terminals such as mobile phones and smartphones. Conventionally, independent inductor components have been mounted on substrates such as circuit boards, but in recent years, a method has been proposed in which a coil is formed using the conductor layer of the substrate and the inductor is directly mounted on the substrate (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2021-086856

[0004] One known method for directly mounting an inductor on a substrate is to form a magnetic layer in a hole in the substrate using a cured resin composition containing a magnetic material, followed by forming a conductive layer on the surface of the magnetic layer. The conductive layer is typically formed by plating. While electroless plating can form a conductive layer on the surface of a non-conductive material, it is generally difficult to achieve a thick conductive layer. On the other hand, electroplating, due to its principle of using an electric current, generally cannot form a conductive layer on the surface of a non-conductive material, making it impossible to form a conductive layer on the surface of a magnetic layer, which is a non-conductive layer. Therefore, conventionally, a thin conductive layer (seed layer) was formed on the surface of a magnetic layer by electroless plating, and then a thick conductive layer was formed on the thin conductive layer by electroplating.

[0005] However, when electroless plating and electroplating are performed in combination, a large number of steps are required to form a conductive layer. The large number of steps tends to increase the number of plating control items and the time required to form a conductive layer. Furthermore, strict component control is generally required for the plating solution used as a chemical solution for electroless plating. Therefore, controlling the components of the plating solution is time-consuming and complicated.

[0006] Therefore, there is a need to develop a technology that allows for the elimination of electroless plating and allows for the formation of a conductive layer on the surface of a magnetic layer by electroplating.

[0007] The present invention has been devised in view of the above-mentioned problems, and aims to provide a method for manufacturing a magnetic substrate, which includes forming a conductive layer on the surface of a magnetic layer by electroplating; and a magnetic substrate, which includes a magnetic layer and a conductive layer formed on the surface of the magnetic layer by electroplating.

[0008] The present inventors conducted extensive research to solve the above-mentioned problems. As a result, the present inventors discovered that a conductor layer can be formed by electroplating on the surface of a cured resin composition containing a combination of (A) magnetic powder containing an (A-1) alloy powder in a specific range of amount and (B) thermosetting resin. The present inventors then discovered that the above-mentioned problems can be solved by applying the cured product to a magnetic layer, and completed the present invention. That is, the present invention includes the following:

[0009] [1] A method for manufacturing a magnetic substrate comprising a magnetic layer and a conductor layer formed on the surface of the magnetic layer, comprising: step (EP) of forming a conductor layer on the surface of the magnetic layer by electroplating, wherein the magnetic layer comprises a cured product of a resin composition containing (A) magnetic powder and (B) a thermosetting resin, and the (A) magnetic powder comprises 30% by mass or more of (A-1) alloy powder relative to 100% by mass of the (A) magnetic powder. [2] A method for manufacturing a magnetic substrate according to [1], comprising: step (LF) of forming a resin composition layer containing a resin composition, and step (CU) of curing the resin composition layer to form a magnetic layer, prior to step (EP). [3] A method for manufacturing a magnetic substrate according to [2], which does not include a step of forming a conductor layer on the surface of the magnetic layer by a method other than electroplating between step (CU) and step (EP). [4] A method for manufacturing a magnetic substrate according to [2] or [3], wherein step (LF) comprises forming a resin composition layer in the first hole of a substrate having first holes formed therein. [5] The method for producing a magnetic substrate according to any one of [1] to [4], comprising a step (HF) of forming second holes in the magnetic layer prior to the step (EP), wherein the step (EP) comprises forming a conductor layer by electroplating on the surface of the second holes in the magnetic layer. [6] The method for producing a magnetic substrate according to any one of [1] to [5], wherein the amount of (A) magnetic powder relative to 100 mass% of nonvolatile components in the resin composition is 60 mass% or more. [7] The method for producing a magnetic substrate according to any one of [1] to [6], wherein the cured product has a relative magnetic permeability of 10 or more at a measurement frequency of 20 MHz. [8] The method for producing a magnetic substrate according to any one of [1] to [7], wherein the (A-1) alloy powder comprises one or more types selected from the group consisting of Fe—Ni-based alloy powder, Fe—Cr—Si-based alloy powder, and Fe—Ni—Cr-based alloy powder. [9] A magnetic substrate comprising a magnetic layer having holes formed therein and a conductor layer formed in the holes, wherein the magnetic layer and the conductor layer are in direct contact with each other and there is no plating catalyst at the interface between the magnetic layer and the conductor layer, the magnetic layer comprises a cured product of a resin composition comprising (A) a magnetic powder and (B) a thermosetting resin, and the (A) magnetic powder comprises 30% by mass or more of an (A-1) alloy powder relative to 100% by mass of the (A) magnetic powder.

[10] The magnetic substrate according to [9], wherein the conductor layer is formed of copper.

[0010] According to the present invention, there can be provided a method for manufacturing a magnetic substrate, which includes forming a conductive layer on the surface of a magnetic layer by electroplating; and a magnetic substrate, which includes a magnetic layer and a conductive layer formed on the surface of the magnetic layer by electroplating.

[0011] FIG. 1 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 2 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 3 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 4 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 5 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 6 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 7 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 8 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 9 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 10 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 11 is a schematic cross-sectional view illustrating steps of a method for manufacturing a magnetic substrate according to an example. FIG. 12 is a schematic cross-sectional view of a magnetic substrate according to an example.

[0012] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the following embodiments and examples, and can be implemented with any modifications within the scope of the claims and their equivalents. In the following description, unless otherwise specified, the resin component of the resin composition refers to the non-volatile components of the resin composition excluding inorganic particles such as (A) magnetic powder.

[0013] [Overview of Magnetic Substrate Manufacturing Method] A manufacturing method according to one embodiment of the present invention is a method for manufacturing a magnetic substrate comprising a magnetic layer and a conductive layer formed on the surface of the magnetic layer. The magnetic layer comprises a cured product of a resin composition comprising (A) magnetic powder and (B) a thermosetting resin. The (A) magnetic powder also comprises an (A-1) alloy powder in a specific amount. Since a conductive layer can be formed on the surface of such a magnetic layer by electroplating, the formation of a conductive layer (seed layer) by electroless plating can be omitted. Therefore, the manufacturing method according to this embodiment can include a step (EP) of forming a conductive layer on the surface of the magnetic layer by electroplating. The conductive layer formed on the surface of the magnetic layer by electroplating will hereinafter be referred to as the "electroplated layer."

[0014] Since the formation of a conductor layer (seed layer) by electroless plating can be omitted, the manufacturing method according to this embodiment reduces the number of steps, enabling the formation of an electroplated layer simply and in a short time. Furthermore, since electroless plating is not required, chemical solutions for electroless plating are not required. Therefore, chemical management of the chemical solutions is not required, simplifying the manufacturing process of the magnetic substrate. This contrasts with the use of chemical solutions for electroless plating, where, depending on the type of (A-1) alloy powder, the (A-1) alloy powder may dissolve in the chemical solution, increasing the complexity of chemical management. Furthermore, since particles of materials that can be dissolved or altered by chemical solutions can be used as the (A-1) alloy powder, the range of options for the (A-1) alloy powder can be expanded. Furthermore, magnetic layers containing such (A-1) alloy powders typically exhibit excellent magnetic properties.

[0015] Generally, in electroplating, metal ions in a plating solution are reduced and deposited on the surface of a cathode to be plated, forming a conductive layer. Because the application of a current is required for the reduction of metal ions, it has been common knowledge among those skilled in the art that the reduction of metal ions occurs only on the surface of a cathode made of a conductor. For example, a conventional magnetic layer with a high volume resistivity could not form a conductive layer on the surface of the magnetic layer, even if electroplating was performed.

[0016] In contrast, in the present embodiment, a magnetic layer containing an (A) magnetic powder containing a specific range of amount of (A-1) alloy powder has a resistance greater than that of a conductor, and yet it is possible to form an electroplated layer as a conductor layer on the surface of the magnetic layer by electroplating. Even if the magnetic layer according to the present embodiment has a volume resistivity similar to that of a conventional magnetic layer, it is possible to form an electroplated layer on the surface of the magnetic layer according to the present embodiment, which contains an (A) magnetic powder containing a specific range of amount of (A-1) alloy powder. Such a phenomenon would be unexpected to those skilled in the art.

[0017] While the present invention is not bound by any particular theory, the inventor speculates as follows about the mechanism by which an electroplated layer is formed on the surface of a magnetic layer by electroplating as described above. Assume a case in which wiring is connected to the magnetic layer for electroplating. Generally, (A-1) alloy powder is conductive, but all or most of the particles of the (A-1) alloy powder are usually insulated from each other by a resin component. Thus, the magnetic layer is usually insulating. However, in a magnetic layer containing a sufficient amount of (A) magnetic powder to achieve the high relative permeability required for a magnetic substrate, the particles of the (A-1) alloy powder in the (A) magnetic powder are close to each other. Thus, when a sufficient voltage is applied, dielectric breakdown of the resin component occurs, allowing current to flow between the particles of the (A-1) alloy powder. Furthermore, if there are portions in the magnetic layer where particles of the (A-1) alloy powder are in contact with each other, a conductive path can be formed by the particles of the (A-1) alloy powder, and a current can flow through that conductive path. When a current flows, metal ions are reduced on the surface of the particles of the (A-1) alloy powder through which the current flows, and the metal can be precipitated. Therefore, electroplating can be performed using the magnetic layer as a cathode, and an electroplated layer can be formed without electroless plating.

[0018] The manufacturing method according to this embodiment may include, before step (EP), a step (LF) of forming a resin composition layer containing a resin composition, and a step (CU) of curing the resin composition layer to form a magnetic layer. Therefore, the manufacturing method according to this embodiment may include, in this order, the step (LF) of forming a resin composition layer, the step (CU) of curing the resin composition layer to form a magnetic layer, and the step (EP) of forming an electroplated layer on the surface of the magnetic layer by electroplating. In this case, the manufacturing method according to this embodiment can manufacture a magnetic substrate without including a step of forming a conductor layer on the surface of the magnetic layer by a method other than electroplating between steps (CU) and (EP).

[0019] [Resin Composition] The resin composition used in the method for producing a magnetic substrate according to one embodiment of the present invention will be described. The resin composition according to this embodiment contains (A) a magnetic powder and (B) a thermosetting resin. Furthermore, this resin composition may contain any component in combination with (A) the magnetic powder and (B) the thermosetting resin.

[0020] <(A) Magnetic Powder> The resin composition according to this embodiment includes (A) magnetic powder as component (A). The (A) magnetic powder may be particles of a material having a relative magnetic permeability greater than 1. The material of the (A) magnetic powder is typically an inorganic material, and may be a soft magnetic material or a hard magnetic material. The material of the (A) magnetic powder may be used alone or in combination of two or more types. Therefore, the (A) magnetic powder may be a soft magnetic powder, a hard magnetic powder, or a combination of a soft magnetic powder and a hard magnetic powder. It is preferable that the (A) magnetic powder include a soft magnetic powder, and more preferably, it includes only a soft magnetic powder. The (A) magnetic powder may be used alone or in combination of two or more types.

[0021] The (A) magnetic powder includes an (A-1) alloy powder. The (A-1) alloy powder as the (A-1) component is alloy particles. Examples of the (A-1) alloy powder include Fe—Si alloy powder, Fe—Si—Al alloy powder, Fe—Cr alloy powder, Fe—Cr—Si alloy powder, Fe—Ni—Cr alloy powder, Fe—Cr—Al alloy powder, Fe—Ni alloy powder, Fe—Ni—Si alloy powder, Fe—Ni—B alloy powder, Fe—Ni—Mo alloy powder, Fe—Ni—Mo—Cu alloy powder, Fe—Co alloy powder, Fe—Ni—Co alloy powder, and Co-based amorphous alloy powder. The alloy contained in the (A-1) alloy powder may be crystalline, amorphous, or a combination thereof.

[0022] Among these, as the (A-1) alloy powder, iron alloy powder as particles of an alloy containing iron is more preferable. Among iron alloy powders, iron alloy powder containing Fe element and at least one element selected from the group consisting of Ni, Cr, and Si is even more preferable, and one or more elements selected from the group consisting of Fe—Ni alloy powder, Fe—Cr—Si alloy powder, and Fe—Ni—Cr alloy powder are particularly preferable. Fe—Ni alloy powder refers to an alloy powder containing Fe and Ni. Furthermore, Fe—Cr—Si alloy powder refers to an alloy powder containing Fe, Cr, and Si. Furthermore, Fe—Ni—Cr alloy powder refers to an alloy powder containing Fe, Ni, and Cr. When these preferable (A-1) alloy powders are used, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating.

[0023] Commercially available (A-1) alloy powders may be used. Examples of commercially available (A-1) alloy powders include "AKT-PB(5)" (Fe—Ni-based alloy powder) and "AKT-PB-3Si(5)" (Fe—Ni—Si-based alloy powder) manufactured by Mitsubishi Steel Corporation; "CVD Iron Powder" (Fe—Cr—Si-based alloy powder) manufactured by JFE Mineral Co., Ltd.; "AW2-08 PF3F" (Fe—Si—Cr-based alloy powder) manufactured by Epson Atmix Corporation; and "MA-RCO-5" (Fe—Ni—B-based alloy) and "MA-RCO-24" (Fe—Ni-based alloy) manufactured by Dowa Electronics Corporation.

[0024] The alloy powder (A-1) may be used singly or in combination of two or more kinds.

[0025] The (A-1) alloy powder preferably has an average particle size within a specific range. The average particle size range of the (A-1) alloy powder is preferably 0.001 μm or more, more preferably 0.01 μm or more, even more preferably 0.1 μm or more, and is preferably 800 μm or less, more preferably 300 μm or less, and even more preferably 100 μm or less. When an (A-1) alloy powder having an average particle size within this range is used, a magnetic layer having excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating.

[0026] Unless otherwise specified, the average particle size refers to the median diameter on a volume basis. This average particle size can be measured by a laser diffraction / scattering method based on the Mie scattering theory. Specifically, a particle size distribution is created on a volume basis using a laser diffraction / scattering particle size distribution measuring device, and the median diameter can be measured as the average particle size. A measurement sample can preferably be one in which powder is dispersed in water using ultrasonic waves. Examples of laser diffraction / scattering particle size distribution measuring devices that can be used include the "LA-500" manufactured by Horiba Ltd. and the "SALD-2200" manufactured by Shimadzu Corporation.

[0027] The specific surface area of ​​the (A-1) alloy powder is preferably 0.05 m from the viewpoint of improving the relative permeability. ２ / g or more, more preferably 0.1 m ２ / g or more, more preferably 0.3m ２ / g or more, preferably 10m ２ / g or less, more preferably 8m ２ / g or less, more preferably 5m ２ / g or less. The specific surface area of ​​the (A-1) alloy powder can be measured by the BET method. Specifically, the specific surface area can be measured according to the BET method by adsorbing nitrogen gas onto the surface of a sample using a specific surface area measuring device ("Macsorb HM Model 1210" manufactured by Mountech Co., Ltd.) and using the BET multipoint method.

[0028] The particles of the (A-1) alloy powder are preferably spherical or ellipsoidal. The aspect ratio, the ratio of the length of the major axis of the particles of the (A-1) alloy powder divided by the length of the minor axis, is preferably 2 or less, more preferably 1.5 or less, even more preferably 1.2 or less, and is usually 1.0 or more. In general, when the shape of the magnetic powder particles is flat rather than spherical, it is easy to improve the relative magnetic permeability. On the other hand, when the shape of the magnetic powder particles is close to spherical, it is easy to reduce magnetic loss.

[0029] The true specific gravity range of the (A-1) alloy powder is, for example, 4 g / cm ３ ~10g / cm ３ It is possible.

[0030] The (A) magnetic powder contains an (A-1) alloy powder in a specific range of amount. The specific amount (mass %) of the (A-1) alloy powder is typically 30 mass % or more, preferably 40 mass % or more, more preferably 50 mass % or more, and may even be 60 mass % or more, relative to 100 mass % of the (A) magnetic powder. The upper limit is typically 100 mass % or less. When the (A-1) alloy powder is used in an amount within this range, an electroplated layer can be formed on the surface of the magnetic layer by electroplating. Furthermore, a magnetic layer with excellent magnetic properties can usually be obtained. Furthermore, preferably, the surface smoothness of the electroplated layer formed can be improved.

[0031] The amount (vol %) of the (A-1) alloy powder is preferably 20 vol % or more, more preferably 30 vol % or more, and even more preferably 40 vol % or more, and may be 50 vol % or more, relative to 100 vol % of the (A) magnetic powder. The upper limit is usually 100 vol % or less. When the (A-1) alloy powder is used in an amount within this range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating. Furthermore, it is preferable that the surface smoothness of the electroplated layer formed can be improved.

[0032] The volumetric amount (vol %) of each component contained in the resin composition can be calculated from the mass of the component contained in the resin composition. Specifically, the volume of each component is calculated by dividing the mass by the specific gravity, and the volumetric amount (vol %) can be calculated from the volume of each component thus calculated.

[0033] The amount (mass %) of the (A-1) alloy powder is preferably 10 mass % or more, more preferably 15 mass % or more, and even more preferably 20 mass % or more, relative to 100 mass % of the nonvolatile components of the resin composition, and is preferably 99 mass % or less, more preferably 98 mass % or less, and even more preferably 97 mass % or less. When the (A-1) alloy powder is used in an amount within this range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating. Furthermore, the smoothness of the surface of the electroplated layer formed can be preferably improved.

[0034] The amount (vol %) of the (A-1) alloy powder is preferably 10 vol % or more, more preferably 13 vol % or more, and even more preferably 16 vol % or more, relative to 100 vol % of the nonvolatile components of the resin composition, and is preferably 90 vol % or less, more preferably 85 vol % or less, and even more preferably 80 vol % or less. When the (A-1) alloy powder is used in an amount within this range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating. Furthermore, preferably, the surface smoothness of the electroplated layer formed can be improved.

[0035] The (A) magnetic powder may contain (A-2) any magnetic powder other than the (A-1) alloy powder. Examples of the (A-2) any magnetic powder include magnetic metal oxide powder and magnetic metal powder other than the (A-1) alloy powder.

[0036] Examples of magnetic metal oxide powders include Fe-Mn ferrite powder, Fe-Mn-Mg ferrite powder, Fe-Mn-Mg-Sr ferrite powder, Fe-Mg-Zn ferrite powder, Fe-Mg-Sr ferrite powder, Fe-Zn-Mn ferrite powder, Fe-Cu-Zn ferrite powder, Fe-Ni-Zn ferrite powder, and Fe-Ni Examples of the ferrite powder include ferrite powders such as Fe—Zn—Cu ferrite powder, Fe—Ba—Zn ferrite powder, Fe—Ba—Mg ferrite powder, Fe—Ba—Ni ferrite powder, Fe—Ba—Co ferrite powder, Fe—Ba—Ni—Co ferrite powder, and Fe—Y ferrite powder; and iron oxide powders such as iron oxide (III) powder and triiron tetroxide powder.

[0037] (A-1) Examples of magnetic metal powders other than alloy powders include pure iron powders.

[0038] (A-2) Among the optional magnetic powders, magnetic metal oxide powders are preferred, and ferrite powders are even more preferred. Ferrite powders are typically composed of composite oxides primarily composed of iron oxide, and are chemically stable. Therefore, ferrite powders offer advantages such as high corrosion resistance, low risk of fire, and resistance to demagnetization. Among these, ferrite powders containing at least one element selected from the group consisting of Mn and Zn are preferred, ferrite powders containing Mn are more preferred, and Fe-Mn ferrite powders and Fe-Mn-Zn ferrite powders are particularly preferred. Fe-Mn ferrite powder refers to ferrite powders containing Fe and Mn, and Fe-Mn-Zn ferrite powder refers to ferrite powders containing Fe, Mn, and Zn.

[0039] As the (A-2) arbitrary magnetic powder, commercially available products may be used. Examples of commercially available (A-2) arbitrary magnetic powder include "M001", "M03S", "M05S", "MZ03S", and "MZ05S" manufactured by Powdertech Co., Ltd.; "AW2-08" manufactured by Epson Atmix Corporation; "LD-M", "LD-MH", "KNI-106", "KNI-106GSM", "KNI-106GS", "KNI-109", and "KNI-109GSM" manufactured by JFE Chemical Corporation; and "KNS-415", "BSF-547", "BSF-029", "BSN-125", "BSN-714", and "BSN-828" manufactured by Toda Kogyo Co., Ltd.

[0040] The optional magnetic powder (A-2) may be used singly or in combination of two or more kinds.

[0041] The average particle size of the (A-2) optional magnetic powder is not particularly limited. The average particle size of the (A-2) optional magnetic powder is preferably smaller than the average particle size of the (A-1) alloy powder. The (A-2) optional magnetic powder, which is smaller than the (A-1) alloy powder, can penetrate into the gaps between the particles of the (A-1) alloy powder. This increases the packing density of the (A) magnetic powder in the magnetic layer as a whole, thereby improving the magnetic properties. Furthermore, such a small (A-2) optional magnetic powder prevents the distance between the particles of the (A-1) alloy powder from widening due to the excluded volume of the particles of the (A-2) optional magnetic powder, thereby facilitating the flow of current during electroplating and allowing for efficient formation of an electroplated layer. The specific range of the average particle size of the (A-2) arbitrary magnetic powder is preferably 0.001 μm or more, more preferably 0.01 μm or more, even more preferably 0.1 μm or more, and preferably 500 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less.

[0042] The specific surface area of ​​the (A-2) arbitrary magnetic powder is not particularly limited. From the viewpoint of improving the relative permeability, the range of the specific surface area of ​​the (A-2) arbitrary magnetic powder is preferably the same as the range of the specific surface area of ​​the (A-1) alloy powder.

[0043] The shape of the (A-2) optional magnetic powder is not particularly limited. For example, the (A-2) optional magnetic powder may have the same shape as the particles of the (A-1) alloy powder. Therefore, the range of the aspect ratio of the particles of the (A-2) optional magnetic powder may be the same as the range of the aspect ratio of the particles of the (A-1) alloy powder.

[0044] The true specific gravity of the (A-2) arbitrary magnetic powder is not particularly limited. For example, the range of the true specific gravity of the (A-2) arbitrary magnetic powder may be the same as the range of the true specific gravity of the (A-1) alloy powder.

[0045] The amount (mass %) of the (A) magnetic powder is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 97% by mass or less, relative to 100% by mass of the non-volatile components of the resin composition. When the total amount of the (A) magnetic powder, including the (A-1) alloy powder and the (A-2) optional magnetic powder, is within the above range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating. In particular, from the viewpoint of improving the smoothness of the electroplated layer, the amount (mass %) of the (A) magnetic powder is preferably 85% by mass or more. When the amount of the (A) magnetic powder is this large, the (A-1) alloy powder, which serves as the starting point for precipitation of metal ions to form the electroplated layer, can be densely distributed, thereby suppressing variation in the degree of precipitation and efficiently obtaining an electroplated layer with a smooth surface.

[0046] The amount (volume %) of the (A) magnetic powder is preferably 30% by volume or more, more preferably 40% by volume or more, and even more preferably 50% by volume or more, relative to 100% by volume of the nonvolatile components of the resin composition. It is preferably 90% by volume or less, more preferably 85% by volume or less, and even more preferably 80% by volume or less. When the total amount of the (A) magnetic powder, including the (A-1) alloy powder and the (A-2) optional magnetic powder, is within the above range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplating layer can be smoothly formed on the surface of the magnetic layer by electroplating. In particular, from the viewpoint of improving the smoothness of the electroplating layer, the amount (volume %) of the (A) magnetic powder is preferably 55% by volume or more. When the amount of the (A) magnetic powder is this large, the (A-1) alloy powder, which serves as the starting point for the deposition of metal ions to form the electroplating layer, can be densely distributed, thereby suppressing variation in the degree of deposition and efficiently obtaining an electroplating layer with a smooth surface.

[0047] <(B) Thermosetting Resin> The resin composition according to this embodiment includes a (B) thermosetting resin as the (B) component. The (B) thermosetting resin can usually bind the (A) magnetic powder. Furthermore, the (B) thermosetting resin reacts with heat to form bonds, thereby curing the resin composition. Therefore, a resin composition containing a combination of the (A) magnetic powder and the (B) thermosetting resin can be cured to form a cured product. The magnetic layer can then be formed from this cured product.

[0048] Examples of the (B) thermosetting resin include epoxy resins, phenolic resins, active ester resins, amine resins, acid anhydride resins, benzoxazine resins, cyanate ester resins, carbodiimide resins, etc. One type of (B) thermosetting resin may be used alone, or two or more types may be used in combination.

[0049] The (B) thermosetting resin preferably contains (B-1) an epoxy resin. The (B-1) epoxy resin refers to a resin having one or more epoxy groups in its molecule. Examples of the (B-1) epoxy resin include bixylenol-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, bisphenol AF-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, phenol novolac-type epoxy resins, glycidyl amine-type epoxy resins, glycidyl ester-type epoxy resins, cresol novolac-type epoxy resins, biphenyl-type epoxy resins, linear aliphatic epoxy resins, epoxy resins having a butadiene structure, alicyclic epoxy resins, and alicyclic epoxy resins having an ester skeleton. Examples of the epoxy resin (B-1) include heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane-type epoxy resins, cyclohexanedimethanol-type epoxy resins, trimethylol-type epoxy resins, tetraphenylethane-type epoxy resins, epoxy resins containing a condensed ring skeleton such as naphthylene ether-type epoxy resins, tert-butyl-catechol-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins, and naphthol novolac-type epoxy resins, isocyanurate-type epoxy resins, epoxy resins containing an alkyleneoxy skeleton and a butadiene skeleton, and epoxy resins containing a fluorene structure. One type of epoxy resin (B-1) may be used alone, or two or more types may be used in combination.

[0050] The epoxy resin (B-1) preferably contains an epoxy resin having two or more epoxy groups per molecule, and the proportion of the epoxy resin having two or more epoxy groups per molecule relative to the total amount of the epoxy resin (B-1) (100% by mass) is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0051] The epoxy resin (B-1) preferably has an aromatic structure. When two or more types of epoxy resins are used, it is preferable that at least one of the epoxy resins has an aromatic structure. An aromatic structure is a chemical structure generally defined as aromatic, and also includes polycyclic aromatic rings and aromatic heterocycles.

[0052] The (B-1) epoxy resin includes an epoxy resin that is liquid at a temperature of 20°C (hereinafter sometimes referred to as a "liquid epoxy resin") and an epoxy resin that is solid at a temperature of 20°C (hereinafter sometimes referred to as a "solid epoxy resin"). The (B-1) epoxy resin may be a liquid epoxy resin alone, a solid epoxy resin alone, or a combination of a liquid epoxy resin and a solid epoxy resin. Of these, the (B-1) epoxy resin preferably contains a liquid epoxy resin, and particularly preferably contains a liquid epoxy resin alone.

[0053] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups per molecule. As the liquid epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, epoxy resin having a butadiene structure, epoxy resin containing an alkyleneoxy skeleton and a butadiene skeleton, epoxy resin containing a fluorene structure, and dicyclopentadiene type epoxy resin are preferred. Among them, bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidyl amine type epoxy resin, and cyclohexane type epoxy resin are particularly preferred.

[0054] Specific examples of liquid epoxy resins include "YX7400" manufactured by Mitsubishi Chemical Corporation; "HP4032", "HP4032D", and "HP4032SS" (naphthalene-type epoxy resins) manufactured by DIC Corporation; "828US", "828EL", "jER828EL", "825", and "Epikote 828EL" (bisphenol A-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; and "jER807" and "1750" (bisphenol F-type epoxy resins) manufactured by Mitsubishi Chemical Corporation. Mitsubishi Chemical Corporation's "jER152" (phenol novolac type epoxy resin); Mitsubishi Chemical Corporation's "630", "630LSD", and "604" (glycidylamine type epoxy resin); ADEKA Corporation's "ED-523T" (glycilol type epoxy resin); ADEKA Corporation's "EP-3950L" and "EP-3980S" (glycidylamine type epoxy resin); ADEKA Corporation's "EP-4088S" (glycidylamine type epoxy resin). "ZX-1059" (a mixture of bisphenol A and bisphenol F epoxy resins) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester epoxy resin) manufactured by Nagase ChemteX Corporation; "EX-991L" (an alkyleneoxy skeleton-containing epoxy resin) manufactured by Nagase ChemteX Corporation; "Celloxide 2021P" and "Celloxide 208" manufactured by Daicel Corporation. 1) (alicyclic epoxy resin having an ester skeleton); "PB-3600" manufactured by Daicel Corporation, "JP-100" and "JP-200" manufactured by Nippon Soda Co., Ltd. (epoxy resins having a butadiene structure); "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane-type epoxy resins) manufactured by Nippon Steel Chemical & Material Co., Ltd.; and "EG-280" (fluorene structure-containing epoxy resin) manufactured by Osaka Gas Chemicals Co., Ltd. Examples of liquid epoxy resins include one type of resin used alone, or two or more types of resins used in combination.

[0055] The solid epoxy resin is preferably a solid epoxy resin having three or more epoxy groups per molecule, more preferably an aromatic solid epoxy resin having three or more epoxy groups per molecule.As the solid epoxy resin, bixylenol type epoxy resin, naphthalene type epoxy resin, naphthalene type tetrafunctional epoxy resin, cresol novolac type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, anthracene type epoxy resin, bisphenol A type epoxy resin, bisphenol AF type epoxy resin, tetraphenylethane type epoxy resin is preferred, and dicyclopentadiene type epoxy resin is particularly preferred.

[0056] Specific examples of solid epoxy resins include "HP4032H" (naphthalene type epoxy resin) manufactured by DIC Corporation; "HP-4700" and "HP-4710" (naphthalene type tetrafunctional epoxy resins) manufactured by DIC Corporation; "N-690" (cresol novolac type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolac type epoxy resin) manufactured by DIC Corporation; and "HP-7200", "HP-7200HH", and "HP-7200H" (dicyclopentadiene type epoxy resins) manufactured by DIC Corporation. "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", and "HP6000" (naphthylene ether type epoxy resins) manufactured by DIC Corporation; "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", and "NC3100" (biphenyl type epoxy resins) manufactured by Nippon Kayaku Co., Ltd. resin); "ESN475V" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN485" (naphthol novolac-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX4000H", "YX4000", and "YX4000HK" (bixylenol-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; Examples of the solid epoxy resin include "YX7700" manufactured by Mitsubishi Chemical Corporation (xylene structure-containing novolac type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YL7760" manufactured by Mitsubishi Chemical Corporation (bisphenol AF type epoxy resin); "YL7800" manufactured by Mitsubishi Chemical Corporation (fluorene type epoxy resin); "jER1010" manufactured by Mitsubishi Chemical Corporation (solid bisphenol A type epoxy resin); and "jER1031S" manufactured by Mitsubishi Chemical Corporation (tetraphenylethane type epoxy resin). One type of solid epoxy resin may be used alone, or two or more types may be used in combination.

[0057] When a liquid epoxy resin and a solid epoxy resin are used in combination as the epoxy resin, the mass ratio of the liquid epoxy resin to the solid epoxy resin (liquid epoxy resin / solid epoxy resin) is preferably 0.5 or more, more preferably 1 or more, even more preferably 5 or more, and still more preferably 10 or more.

[0058] The epoxy equivalent of the (B-1) epoxy resin is preferably 50 g / eq. to 5000 g / eq., more preferably 60 g / eq. to 3000 g / eq., even more preferably 80 g / eq. to 2000 g / eq., and even more preferably 110 g / eq. to 1000 g / eq. The epoxy equivalent is the mass of a resin containing one equivalent of epoxy groups. This epoxy equivalent can be measured in accordance with JIS K7236.

[0059] The weight average molecular weight (Mw) of the epoxy resin (B-1) is preferably 100 to 5000, more preferably 250 to 3000, and even more preferably 400 to 1500. The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene-equivalent value.

[0060] The amount (mass %) of the epoxy resin (B-1) contained in the resin composition is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, and even more preferably 1 mass % or more, relative to 100 mass % of the nonvolatile components of the resin composition, and is preferably 20 mass % or less, more preferably 15 mass % or less, and even more preferably 10 mass % or less. When the amount of the epoxy resin (B-1) is within this range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating.

[0061] The amount (mass %) of the (B-1) epoxy resin contained in the resin composition is preferably 10 mass % or more, more preferably 20 mass % or more, and even more preferably 30 mass % or more, relative to 100 mass % of the resin components of the resin composition, and is preferably 96 mass % or less, more preferably 93 mass % or less, and even more preferably 90 mass % or less. When the amount of the (B-1) epoxy resin is within this range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating.

[0062] The range of the amount (mass %) of the (B-1) epoxy resin contained in the resin composition is, relative to 100 mass % of the (A) magnetic powder, preferably 0.1 mass % or more, more preferably 0.5 mass % or more, even more preferably 1 mass % or more, and preferably 20 mass % or less, more preferably 16 mass % or less, even more preferably 12 mass % or less. When the amount of the (B-1) epoxy resin is within this range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating.

[0063] When the (B) thermosetting resin contains the (B-1) epoxy resin, the (B) thermosetting resin preferably contains a resin capable of reacting with and bonding to the (B-1) epoxy resin. Hereinafter, the resin capable of reacting with the (B-1) epoxy resin to bond may be referred to as the "(B-2) curing agent." Examples of the (B-2) curing agent include phenolic resins, active ester resins, amine resins, carbodiimide resins, acid anhydride resins, benzoxazine resins, cyanate ester resins, and thiol resins. One type of (B-2) curing agent may be used alone, or two or more types may be used in combination. Among these, phenolic resins are preferred.

[0064] As the phenolic resin, a resin having one or more, preferably two or more, hydroxyl groups bonded to an aromatic ring such as a benzene ring or a naphthalene ring per molecule can be used. From the viewpoint of heat resistance and water resistance, a phenolic resin having a novolac structure is preferred. From the viewpoint of adhesion, a nitrogen-containing phenolic resin is preferred, and a triazine skeleton-containing phenolic resin is more preferred. Among them, a triazine skeleton-containing phenolic novolac resin is preferred from the viewpoint of highly satisfying heat resistance, water resistance, and adhesion.

[0065] Specific examples of phenolic resins include "MEH-7700", "MEH-7810", "MEH-7851", and "MEH-8000H" manufactured by Meiwa Chemical Industry Co., Ltd.; "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd.; and "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-495V", "SN-375", and "SN" manufactured by Nippon Steel Chemical & Material Co., Ltd. -395"; "TD-2090", "TD-2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "EXB-9500", "HPC-9500", "KA-1160", "KA-1163", and "KA-1165" manufactured by DIC Corporation; and "GDP-6115L", "GDP-6115H", and "ELPC75" manufactured by Gun-ei Chemical Co., Ltd.

[0066] As the activated ester resin, a compound having one or more, preferably two or more, activated ester groups per molecule can be used. Among these, preferred activated ester resins are compounds having two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. The activated ester resin is preferably one obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound. In particular, from the viewpoint of improving heat resistance, activated ester resins obtained from a carboxylic acid compound and a hydroxy compound are preferred, and activated ester resins obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound are more preferred. Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolak, etc. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0067] Specific preferred examples of the active ester resin include active ester resins containing a dicyclopentadiene-type diphenol structure, active ester resins containing a naphthalene structure, active ester resins containing an acetylated product of phenol novolac, and active ester resins containing a benzoylated product of phenol novolac. Among these, active ester resins containing a naphthalene structure and active ester resins containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

[0068] Commercially available activated ester resins include activated ester resins containing a dicyclopentadiene-type diphenol structure such as "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T", "HPC-8000H-65TM", and "EXB-8000L-65TM" (manufactured by DIC Corporation); activated ester resins containing a naphthalene structure such as "EXB-9416-70BK", "EXB-8150-65T", "EXB-8100L-65T", and "EXB-8150L-65T" (manufactured by DIC Corporation); and phenol novolac resins such as "EXB-9416-70BK", "EXB-8150-65T", "EXB-8100L-65T", and "EXB-8150L-65T" (manufactured by DIC Corporation). Examples of active ester resins containing acetylated products include "DC808" (manufactured by Mitsubishi Chemical Corporation); examples of active ester resins containing benzoylated phenol novolac include "YLH1026" (manufactured by Mitsubishi Chemical Corporation); examples of active ester resins that are acetylated phenol novolac include "DC808" (manufactured by Mitsubishi Chemical Corporation); and examples of active ester resins that are benzoylated phenol novolac include "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), and "YLH1048" (manufactured by Mitsubishi Chemical Corporation).

[0069] As the amine-based resin, a resin having one or more, preferably two or more amino groups in one molecule can be used. Examples of the amine-based resin include aliphatic amines, polyether amines, alicyclic amines, and aromatic amines. Among these, aromatic amines are preferred. The amine-based resin is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of the amine-based resin include 4,4'-methylenebis(2,6-dimethylaniline), diphenyldiaminosulfone, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-hydroxybenzoyl) phenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, and the like. Commercially available amine resins may be used, and examples thereof include "KAYABOND C-200S," "KAYABOND C-100," "KAYAHARD A-A," "KAYAHARD A-B," and "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd., and "Epicure W" manufactured by Mitsubishi Chemical Corporation.

[0070] As the carbodiimide resin, a resin having one or more, preferably two or more, carbodiimide structures in one molecule can be used. Specific examples of the carbodiimide resin include aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexanebis(methylene-t-butylcarbodiimide); aromatic biscarbodiimides such as phenylene-bis(xylylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylenecarbodiimide, polytrimethylhexamethylenecarbodiimide, polycyclohexylenecarbodiimide, poly(methylenebiscyclohexylenecarbodiimide), and poly(isophoronecarbodiimide); poly(phenylenecarbodiimide), poly(naphthalenecarbodiimide); Examples of polycarbodiimides include aromatic polycarbodiimides such as poly(methylenebis(methylphenylene)carbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylylenecarbodiimide), poly(tetramethylxylylenecarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylene)carbodiimide]. Commercially available carbodiimide resins include, for example, "Carbodilite V-02B," "Carbodilite V-03," "Carbodilite V-04K," "Carbodilite V-07," and "Carbodilite V-09," manufactured by Nisshinbo Chemical Inc.; and "Stavaxol P," "Stavaxol P400," and "Hykasil 510," manufactured by Rhein Chemie.

[0071] As the acid anhydride resin, a resin having one or more acid anhydride groups in one molecule can be used, and a resin having two or more acid anhydride groups in one molecule is preferred. Specific examples of the acid anhydride resin include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, and benzophenonetetracarboxylic dianhydride. anhydride, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(anhydrotrimellitate), polymeric acid anhydrides such as styrene-maleic acid resins in which styrene and maleic acid are copolymerized, and the like. Examples of commercially available acid anhydride resins include "HNA-100," "MH-700," "MTA-15," "DDSA," and "OSA" manufactured by New Japan Chemical Co., Ltd.; "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Corporation; "HN-2200" and "HN-5500" manufactured by Hitachi Chemical Co., Ltd.; and "EF-30," "EF-40," "EF-60," and "EF-80" manufactured by Clay Valley Corporation.

[0072] Specific examples of benzoxazine resins include "JBZ-OD100", "JBZ-OP100D", and "ODA-BOZ" manufactured by JFE Chemical Corporation; "P-d" and "F-a" manufactured by Shikoku Chemicals Corporation; and "HFB2006M" manufactured by Showa Polymer Co., Ltd.

[0073] Examples of cyanate ester resins include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; polyfunctional cyanate resins derived from phenol novolac, cresol novolac, etc.; and prepolymers in which these cyanate resins are partially triazine-converted. Specific examples of cyanate ester resins include "PT30" and "PT60" (phenol novolac type multifunctional cyanate ester resins), "ULL-950S" (multifunctional cyanate ester resin), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine-converted to form a trimer), all of which are manufactured by Lonza Japan.

[0074] Examples of thiol-based resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0075] The active group equivalent of the (B-2) curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., even more preferably 100 g / eq. to 500 g / eq., and still more preferably 100 g / eq. to 300 g / eq. The active group equivalent represents the mass of the (B-2) curing agent per equivalent of the active group.

[0076] When the number of epoxy groups in the (B-1) epoxy resin is taken as 1, the number of active groups in the (B-2) curing agent is preferably 0.01 or more, more preferably 0.1 or more, even more preferably 0.5 or more, and preferably 10 or less, more preferably 5 or less, and even more preferably 2 or less. The active groups in the (B-2) curing agent are active hydroxyl groups, etc., and vary depending on the type of curing agent. The number of epoxy groups in the (B-1) epoxy resin is the sum of the values ​​obtained by dividing the mass of each epoxy resin by the epoxy equivalent for all epoxy resins. The number of active groups in the (B-2) curing agent is the sum of the values ​​obtained by dividing the mass of each curing agent by the active group equivalent for all curing agents.

[0077] The amount (% by mass) of the (B-2) curing agent contained in the resin composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of the non-volatile components of the resin composition, and is preferably 15% by mass or less, more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0078] The amount (% by mass) of the (B-2) curing agent contained in the resin composition is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, relative to 100% by mass of the resin component of the resin composition, and is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0079] When (B) thermosetting resins are classified by viscosity, the (B) thermosetting resin may contain a reactive diluent. The reactive diluent refers to a component of the (B) thermosetting resin that has a low viscosity. The specific viscosity of the reactive diluent is usually less than 0.5 Pa·s. There is no particular lower limit to the viscosity of the reactive diluent, and it may be, for example, 0.001 Pa·s or more, 0.005 Pa·s or more, or 0.01 Pa·s or more. The viscosity of the reactive diluent can be measured using an E-type viscometer at 25±2°C. When the (B) thermosetting resin contains a reactive diluent, the viscosity of the resin composition can be reduced, thereby improving the coatability of liquid resin compositions such as magnetic pastes and magnetic inks.

[0080] The reactive diluent may contain a reactive group such as the above-mentioned epoxy group or active group. Preferred examples of the reactive group contained in the reactive diluent include an epoxy group, an acrylic group, a methacrylic group, an oxetane group, etc., and among these, an epoxy group is preferred. Therefore, it is preferable to use an epoxy resin (B-1) having a low viscosity as the reactive diluent.

[0081] Examples of commercially available reactive diluents include "EX-201" (alicyclic glycidyl ether), "EX-830", "EX-821" (ethylene glycol-type epoxy resin), and "EX-212" (hexanediol-type epoxy resin), all manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane), all manufactured by ADEKA Corporation; "EP-3980S" (glycidylamine-type epoxy resin), "EP-4088S", "EP-4088L" (dicyclopentadiene-type epoxy resin), and "ED-509S" (tert-butylphenyl glycidyl ether), all manufactured by Shin-Etsu Chemical Co., Ltd.; and "X-22-163" (siloxane-type epoxy resin), all manufactured by Shin-Etsu Chemical Co., Ltd. One type of reactive diluent may be used alone, or two or more types may be used in combination.

[0082] The amount (mass %) of the reactive diluent contained in the resin composition is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, and even more preferably 1 mass % or more, relative to 100 mass % of the non-volatile components of the resin composition, and is preferably 20 mass % or less, more preferably 10 mass % or less, and even more preferably 7 mass % or less.

[0083] The amount (mass %) of the reactive diluent contained in the resin composition is preferably 5 mass % or more, more preferably 10 mass % or more, and even more preferably 20 mass % or more, relative to 100 mass % of the resin components of the resin composition, and is preferably 80 mass % or less, more preferably 70 mass % or less, and even more preferably 60 mass % or less.

[0084] The amount (mass%) of the reactive diluent contained in the resin composition is preferably 5 mass% or more, more preferably 10 mass% or more, and even more preferably 20 mass% or more, relative to 100 mass% of the thermosetting resin (B), and is preferably 90 mass% or less, more preferably 80 mass% or less, and even more preferably 70 mass% or less.

[0085] The range of the weight average molecular weight (Mw) of the thermosetting resin (B) can usually be the same as the range of the weight average molecular weight of the epoxy resin (B-1) described above.

[0086] The amount (% by mass) of the (B) thermosetting resin contained in the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of the nonvolatile components of the resin composition, and is preferably 15% by mass or less, more preferably 13% by mass or less, and even more preferably 10% by mass or less. When the amount of the (B) thermosetting resin is within this range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating.

[0087] The amount (mass %) of the (B) thermosetting resin contained in the resin composition is preferably 40 mass % or more, more preferably 50 mass % or more, and even more preferably 60 mass % or more, relative to 100 mass % of the resin components of the resin composition, and is preferably 98 mass % or less, more preferably 94 mass % or less, and even more preferably 90 mass % or less. When the amount of the (B) thermosetting resin is within this range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating.

[0088] The amount (% by mass) of the (B) thermosetting resin contained in the resin composition is preferably 0.1% by mass or more, more preferably 1% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of the (A) magnetic powder, and is preferably 20% by mass or less, more preferably 16% by mass or less, and even more preferably 12% by mass or less. When the amount of the (B) thermosetting resin is within this range, a magnetic layer with excellent magnetic properties can be obtained, and an electroplated layer can be smoothly formed on the surface of the magnetic layer by electroplating.

[0089] <(C) Curing Accelerator> The resin composition according to this embodiment may further contain a (C) curing accelerator as an optional component in combination with the above-described components (A) and (B). The (C) curing accelerator as component (C) does not include components corresponding to the above-described components (A) and (B). The (C) curing accelerator functions as a catalyst that accelerates the curing reaction of the (B) thermosetting resin, and can therefore accelerate the curing of the resin composition.

[0090] Examples of the (C) curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. Among these, imidazole-based curing accelerators are preferred. One type of (C) curing accelerator may be used alone, or two or more types may be used in combination.

[0091] Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-phenylimidazole. 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2, 4-Diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole,

[0039] Examples of the imidazole compound include imidazole compounds such as 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds with epoxy resins, with 2-ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole being preferred. As the imidazole-based curing accelerator, commercially available products may be used, and examples thereof include "P200-H50" manufactured by Mitsubishi Chemical Corporation; and "Curezol 2MZ", "2E4MZ", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", "Cl1Z-A", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2MZA-PW", "2PHZ", and "2PHZ-PW" manufactured by Shikoku Chemicals Corporation.

[0092] Examples of the amine curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, 1,8-diazabicyclo[5,4,0]undecene-7,4-dimethylaminopyridine, and 2,4,6-tris(dimethylaminomethyl)phenol, with 4-dimethylaminopyridine being preferred.

[0093] Examples of the phosphorus-based curing accelerator include triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate, with triphenylphosphine and tetrabutylphosphonium decanoate being preferred.

[0094] Examples of guanidine curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene. Examples of suitable biguanide include 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide. Of these, dicyandiamide and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred.

[0095] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organic cobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organic copper complexes such as copper(II) acetylacetonate, organic zinc complexes such as zinc(II) acetylacetonate, organic iron complexes such as iron(III) acetylacetonate, organic nickel complexes such as nickel(II) acetylacetonate, and organic manganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0096] The amount (mass%) of the (C) curing accelerator contained in the resin composition may be 0 mass% or more than 0 mass%, and is preferably 0.001 mass% or more, more preferably 0.01 mass% or more, even more preferably 0.1 mass% or more, and is preferably 5 mass% or less, more preferably 3 mass% or less, even more preferably 1 mass% or less, relative to 100 mass% of the non-volatile components of the resin composition.

[0097] The amount (mass %) of the (C) curing accelerator contained in the resin composition may be 0 mass % or more than 0 mass %, and is preferably 0.01 mass % or more, more preferably 0.1 mass % or more, and even more preferably 1 mass % or more, relative to 100 mass % of the resin component of the resin composition, and is preferably 20 mass % or less, more preferably 15 mass % or less, and even more preferably 10 mass % or less.

[0098] The amount (mass%) of the (C) curing accelerator contained in the resin composition may be 0 mass% or more than 0 mass%, and is preferably 0.01 mass% or more, more preferably 0.1 mass% or more, and even more preferably 1 mass% or more, relative to 100 mass% of the (B) thermosetting resin, and is preferably 20 mass% or less, more preferably 15 mass% or less, and even more preferably 10 mass% or less.

[0099] <(D) Thermoplastic Resin> The resin composition according to this embodiment may further contain a (D) thermoplastic resin as an optional component in combination with the above-described (A) to (C) components. The (D) thermoplastic resin as this (D) component does not include those corresponding to the above-described (A) to (C) components. The (D) thermoplastic resin can effectively improve the mechanical properties of the magnetic layer.

[0100] Examples of the thermoplastic resin (D) include phenoxy resin, polyimide resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, polyetheretherketone resin, polyester resin, etc. The thermoplastic resin (D) may be used singly or in combination of two or more.

[0101] Examples of the phenoxy resin include phenoxy resins having one or more skeletons selected from the group consisting of a bisphenol A skeleton, a bisphenol F skeleton, a bisphenol S skeleton, a bisphenolacetophenone skeleton, a novolac skeleton, a biphenyl skeleton, a fluorene skeleton, a dicyclopentadiene skeleton, a norbornene skeleton, a naphthalene skeleton, an anthracene skeleton, an adamantane skeleton, a terpene skeleton, and a trimethylcyclohexane skeleton. Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both phenoxy resins containing a bisphenol A skeleton); "YX8100" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol S skeleton); "YX6954" manufactured by Mitsubishi Chemical Corporation (phenoxy resin containing a bisphenol acetophenone skeleton); "FX280" and "FX293" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; and "YL7500BH30," "YX6954BH30," "YX7553," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," "YL7482," and "YL7891BH30" manufactured by Mitsubishi Chemical Corporation.

[0102] Specific examples of polyimide resins include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., and "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. Specific examples of polyimide resins also include modified polyimides such as linear polyimides obtained by reacting bifunctional hydroxyl group-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (e.g., polyimides described in JP-A-2006-37083), and polysiloxane skeleton-containing polyimides (e.g., polyimides described in JP-A-2002-12667 and JP-A-2000-319386).

[0103] Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include "Denka Butyral 4000-2," "Denka Butyral 5000-A," "Denka Butyral 6000-C," and "Denka Butyral 6000-EP" manufactured by Denki Kagaku Kogyo Co., Ltd.; and S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, and BM series manufactured by Sekisui Chemical Co., Ltd.

[0104] Examples of polyolefin resins include ethylene copolymer resins such as low-density polyethylene, very low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; and polyolefin polymers such as polypropylene and ethylene-propylene block copolymer.

[0105] Examples of polybutadiene resins include hydrogenated polybutadiene skeleton-containing resins, hydroxy group-containing polybutadiene resins, phenolic hydroxy group-containing polybutadiene resins, carboxy group-containing polybutadiene resins, acid anhydride group-containing polybutadiene resins, epoxy group-containing polybutadiene resins, isocyanate group-containing polybutadiene resins, urethane group-containing polybutadiene resins, and polyphenylene ether-polybutadiene resins.

[0106] Specific examples of polyamide-imide resins include "Vylomax HR11NN" and "Vylomax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins also include modified polyamide-imides such as "KS9100" and "KS9300" (polysiloxane skeleton-containing polyamide-imides) manufactured by Hitachi Chemical Co., Ltd.

[0107] A specific example of the polyetherimide resin is "Ultem" manufactured by GE.

[0108] Specific examples of polysulfone resins include polysulfone "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

[0109] A specific example of the polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0110] A specific example of the polyphenylene ether resin is "NORYL SA90" manufactured by SABIC.

[0111] Examples of polycarbonate resins include hydroxy group-containing carbonate resins, phenolic hydroxy group-containing carbonate resins, carboxy group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, urethane group-containing carbonate resins, etc. Specific examples of polycarbonate resins include "FPC0220" manufactured by Mitsubishi Gas Chemical Company, Inc., "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090", "C-2090", and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd.

[0112] A specific example of the polyether ether ketone resin is "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

[0113] Examples of polyester resins include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polytrimethylene terephthalate resin, polytrimethylene naphthalate resin, and polycyclohexane dimethyl terephthalate resin.

[0114] The weight average molecular weight (Mw) of the thermoplastic resin (D) is preferably greater than 5,000, more preferably at least 8,000, even more preferably at least 10,000, and still more preferably at least 20,000. There is no particular upper limit, and it can be, for example, 1,000,000 or less, 500,000 or less, or 100,000 or less.

[0115] The amount (mass%) of the thermoplastic resin (D) contained in the resin composition may be 0 mass% or more than 0 mass%, and is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, even more preferably 0.1 mass% or more, and is preferably 5 mass% or less, more preferably 3 mass% or less, even more preferably 1 mass% or less, relative to 100 mass% of the non-volatile components of the resin composition.

[0116] The amount (mass %) of the (D) thermoplastic resin contained in the resin composition may be 0 mass % or more than 0 mass %, and is preferably 1 mass % or more, more preferably 5 mass % or more, and even more preferably 10 mass % or more, and is preferably 30 mass % or less, more preferably 20 mass % or less, and even more preferably 15 mass % or less, relative to 100 mass % of the resin components of the resin composition.

[0117] The amount (mass %) of the (D) thermoplastic resin contained in the resin composition may be 0 mass % or greater than 0 mass % relative to 100 mass % of the (A) magnetic powder, and is preferably 0.01 mass % or greater, more preferably 0.05 mass % or greater, even more preferably 0.1 mass % or greater, and is preferably 5 mass % or less, more preferably 3 mass % or less, and even more preferably 1 mass % or less.

[0118] <(E) Dispersant> The resin composition according to this embodiment may further contain a (E) dispersant as an optional component in combination with the above-described (A) to (D) components. The (E) dispersant as this (E) component does not include those corresponding to the above-described (A) to (D) components. The (E) dispersant can effectively improve the dispersibility of the (A) magnetic powder.

[0119] As the (E) dispersant, a compound capable of reducing the viscosity of the resin composition can be used. Examples of the (E) dispersant include phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants. As the (E) dispersant, one type may be used alone, or two or more types may be used in combination. Among these, phosphate ester-based dispersants are preferred.

[0120] Among phosphate ester-based dispersants, polyether-type phosphate ester-based dispersants are preferred. Polyether-type phosphate ester-based dispersants are phosphate ester-based dispersants containing a poly(alkyleneoxy) structure in the molecule. Examples of polyether-type phosphate ester-based dispersants include polyoxyalkylene alkyl ether phosphate esters and polyoxyalkylene alkylphenyl ether phosphate esters. Among these, polyoxyalkylene alkyl ether phosphate esters are preferred.

[0121] The polyoxyalkylene alkyl ether phosphate ester may have a structure in which 1 to 3 alkyl-oxy-poly(alkyleneoxy) groups are bonded to the phosphorus atom of the phosphate. The number of alkyleneoxy units (repeating units) in the poly(alkyleneoxy) moiety in the alkyl-oxy-poly(alkyleneoxy) group is preferably 2 to 30, more preferably 3 to 20. The alkylene group in the poly(alkyleneoxy) moiety is preferably an alkylene group having 2 to 4 carbon atoms. Examples of such alkylene groups include an ethylene group, a propylene group, an isopropylene group, a butylene group, and an isobutyl group. Furthermore, the alkyl group in the alkyl-oxy-poly(alkyleneoxy) group is preferably an alkyl group having 6 to 30 carbon atoms, more preferably an alkyl group having 8 to 20 carbon atoms. Examples of such alkyl groups include decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl groups. When the polyoxyalkylene alkyl ether phosphate ester has multiple alkyl-oxy-poly(alkyleneoxy) groups, the multiple alkyl groups may be the same or different. Furthermore, the multiple alkylene groups may be the same or different.

[0122] Examples of commercially available phosphate ester dispersants include polyether phosphate ester dispersants manufactured by Kusumoto Chemical Industries Co., Ltd. (for example, HIPLAAD series "ED152", "ED153", "ED154", "ED118", "ED174", "ED251", etc.); and Phosphanol series "RS-410", "RS-610", "RS-710" manufactured by Toho Chemical Industry Co., Ltd.

[0123] Examples of polyoxyalkylene dispersants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkylamines, polyoxyethylene alkylamides, etc. Commercially available examples of polyoxyalkylene dispersants include "AKM-0531," "AFB-1521," "SC-0505K," "SC-1015F," and "SC-0708A," as well as "HKM-50A," from the "Marialim" series manufactured by NOF Corporation.

[0124] An example of an acetylene-based dispersant is acetylene glycol. Examples of commercially available acetylene-based dispersants include "82", "104", "440", "465", and "485" from the "Surfynol" series manufactured by Air Products and Chemicals Inc., as well as "Olefin Y".

[0125] Examples of silicone-based dispersants include polyether-modified polydimethylsiloxane, polyether-modified siloxane, polyester-modified polydimethylsiloxane, etc. Examples of commercially available silicone-based dispersants include "BYK347" and "BYK348" manufactured by BYK-Chemie.

[0126] Examples of anionic dispersants include sodium polyacrylate, sodium dodecyl benzelsulfonate, sodium laurate, polyoxyethylene alkyl ether ammonium sulfate, carboxymethyl cellulose sodium salt, etc. Examples of commercially available anionic dispersants include "PN-411" and "PA-111" manufactured by Ajinomoto Fine-Techno Co., Ltd., and "A-550" and "PS-1900" manufactured by Lion Corporation.

[0127] Examples of cationic dispersants include amino group-containing polyacrylate resins, amino group-containing polystyrene resins, etc. Commercially available examples of cationic dispersants include "161", "162", "164", "182", "2000", and "2001" manufactured by BYK-Chemie; "PB-821", "PB-822", and "PB-824" manufactured by Ajinomoto Fine-Techno Co., Ltd.; "V-216" and "V-220" manufactured by ISP Japan; and "Solsperse 13940", "Solsperse 24000", and "Solsperse 32000" manufactured by Lubrizol Corporation.

[0128] The dispersant (E) may be used alone or in combination of two or more.

[0129] The amount (mass%) of the dispersant (E) contained in the resin composition may be 0 mass% or more than 0 mass%, and is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, even more preferably 0.1 mass% or more, and is preferably 5 mass% or less, more preferably 3 mass% or less, even more preferably 1 mass% or less, relative to 100 mass% of the non-volatile components of the resin composition.

[0130] The amount (mass%) of the dispersant (E) contained in the resin composition may be 0 mass% or more than 0 mass%, and is preferably 0.1 mass% or more, more preferably 1 mass% or more, and even more preferably 5 mass% or more, relative to 100 mass% of the resin component of the resin composition, and is preferably 30 mass% or less, more preferably 20 mass% or less, and even more preferably 15 mass% or less.

[0131] The amount (mass %) of the (E) dispersant contained in the resin composition may be 0 mass % or more than 0 mass % relative to 100 mass % of the (A) magnetic powder, and is preferably 0.01 mass % or more, more preferably 0.05 mass % or more, even more preferably 0.1 mass % or more, and is preferably 5 mass % or less, more preferably 3 mass % or less, even more preferably 1 mass % or less.

[0132] <(F) Optional Additive> The resin composition according to the present embodiment may further contain (F) optional additive as an optional component in combination with the above-described (A) to (E) components. The (F) optional additive as the (F) component does not include those corresponding to the above-described (A) to (E) components.

[0133] (F) Examples of optional additives include inorganic fillers such as silica particles; organic fillers such as rubber particles; organometallic compounds such as organocopper compounds and organozinc compounds; radical polymerization initiators such as peroxide radical polymerization initiators and azo radical polymerization initiators; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone leveling agents and acrylic polymer leveling agents; thickeners such as bentone and montmorillonite; antifoaming agents such as silicone antifoaming agents, acrylic antifoaming agents, fluorine-based antifoaming agents, and vinyl resin antifoaming agents; ultraviolet absorbers such as benzotriazole ultraviolet absorbers; urea silica Examples of the optional additives (F) include adhesion improvers such as phenols; adhesion promoters such as triazole-based adhesion promoters, tetrazole-based adhesion promoters, and triazine-based adhesion promoters; antioxidants such as hindered phenol-based antioxidants; flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, and red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide); and stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers. One type of optional additive (F) may be used alone, or two or more types may be used in combination.

[0134] <(G) Solvent> The resin composition may further contain a (G) solvent as a volatile component in addition to the non-volatile components (A) to (F) described above. An organic solvent is typically used as the (G) solvent. Examples of the organic solvent include ketone-based solvents such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether-based solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, and diphenyl ether; alcohol-based solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, butyl carbitol acetate, ethyl diglycol acetate, γ-butyrolactone, methoxy methyl ether, methyl methyl ether, methyl ethyl ether, methyl methyl ether, ethyl methyl ether, γ-butyrolactone, methyl methyl ether, methyl ethyl ether ... Examples of the solvent (G) include ether ester solvents such as methyl propionate; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. The solvent (G) may be used alone or in combination of two or more.

[0135] <Method for producing resin composition> The resin composition according to this embodiment can be produced, for example, by mixing the above-mentioned components. Some or all of the above-mentioned components may be mixed simultaneously, or may be mixed sequentially. In the process of mixing each component, the temperature may be appropriately set, and thus heating and / or cooling may be performed temporarily or throughout. Furthermore, stirring or shaking may be performed in the process of mixing each component.

[0136] <Characteristics of Resin Composition> The resin composition according to this embodiment can be cured by heat. Therefore, a cured product of the resin composition can be obtained by thermally curing the resin composition. Typically, among the components contained in the resin composition, volatile components such as solvent (G) can volatilize due to the heat during thermal curing, but non-volatile components such as components (A) to (F) do not volatilize due to the heat during thermal curing. Therefore, the cured product of the resin composition can contain the non-volatile components of the resin composition or their reaction products. The cured product of the resin composition can have excellent magnetic properties such as relative magnetic permeability and magnetic loss. Therefore, this cured product can be used as a material for the magnetic layer of a magnetic substrate.

[0137] The cured product of the resin composition according to this embodiment typically has a high relative magnetic permeability μ'. The specific range of the relative magnetic permeability μ' of the cured product is preferably 10 or more, more preferably 12 or more, and even more preferably 15 or more. The upper limit of the relative magnetic permeability μ' is not particularly limited and may be, for example, 35 or less, 30 or less, or 25 or less. When using a resin composition containing (A) magnetic powder in an amount sufficient to achieve a relative magnetic permeability within this range, the method for manufacturing a magnetic substrate according to this embodiment can smoothly form an electroplated layer by electroplating on the surface of a magnetic layer containing a cured product of the resin composition. The relative magnetic permeability μ' of the cured product can be measured at a measurement frequency of 20 MHz and a room temperature of 23°C. Furthermore, when curing a resin composition to measure the relative magnetic permeability μ', the resin composition can be thermally cured at 190°C for 90 minutes to obtain a cured product as a measurement sample. A specific method for measuring the relative magnetic permeability μ' can be adopted, as described in the Examples below.

[0138] The cured product of the resin composition according to this embodiment typically exhibits low magnetic loss. Magnetic loss can be expressed by the loss factor tan δ, and typically, the smaller the loss factor tan δ, the smaller the magnetic loss. The specific range of the loss factor tan δ of the cured product is preferably 0.05 or less, more preferably 0.04 or less, and even more preferably 0.03 or less. The lower limit of the loss factor tan δ is not particularly limited and can be, for example, 0.001 or more. When using a resin composition containing (A) magnetic powder in an amount sufficient to achieve a magnetic loss within this range, the method for manufacturing a magnetic substrate according to this embodiment can smoothly form an electroplated layer by electroplating on the surface of a magnetic layer containing a cured product of the resin composition. The loss factor tan δ of the cured product can be measured at a measurement frequency of 20 MHz and a room temperature of 23°C. Furthermore, when curing a resin composition to measure the loss factor tan δ, the resin composition can be thermally cured at 190°C for 90 minutes to obtain a cured product as a measurement sample. The specific method for measuring the loss factor tan δ can be as described in the Examples section below.

[0139] The cured product of the resin composition according to this embodiment can usually have a high volume resistivity. Therefore, the cured product can form an insulating magnetic layer. The specific volume resistivity range of the cured product is preferably 1.0 × 10 ８ Ω·m or more, more preferably 5.0×10 ８ Ω·m or more, more preferably 1.0×10 ９ Ω·m or more, preferably 1.0×10 １３ Ω·m or less, more preferably 5.0×10 １２ Ω·m or less, more preferably 1.0×10 １２ The volume resistivity of the cured product is Ω·m or less. It is surprising from the perspective of common technical knowledge of those skilled in the art that an electroplated layer can be formed by electroplating on the surface of a magnetic layer formed from a cured product with such a high volume resistivity. The volume resistivity of the cured product can be measured using the method described in the Examples below.

[0140] There are no particular limitations on the properties of the resin composition. Therefore, the resin composition may be a liquid having fluidity. For example, the resin composition may be a liquid resin composition that does not contain a (G) solvent, or a liquid resin composition that contains a (G) solvent. Hereinafter, a liquid resin composition that does not contain a (G) solvent may be referred to as a "magnetic paste," and a liquid resin composition that contains a (G) solvent may be referred to as a "magnetic ink."

[0141] Liquid resin compositions such as magnetic pastes and magnetic inks have fluidity and can therefore be preferably used to form magnetic layers using printing methods. The liquid resin composition is preferably liquid at 23°C. The viscosity of this liquid resin composition at 23°C is preferably 20 Pa·s or more, more preferably 25 Pa·s or more, even more preferably 30 Pa·s or more, and particularly preferably 50 Pa·s or more, and is preferably 200 Pa·s or less, more preferably 180 Pa·s or less, and even more preferably 160 Pa·s or less. The viscosity can be measured, for example, using an E-type viscometer (Toki Sangyo Co., Ltd.'s "RE-80U," 3° x R9.7 rotor) under measurement conditions of a sample volume of 0.22 ml and a rotation speed of 5 rpm.

[0142] The resin composition may be in a solid form. The form of the solid resin composition is not particularly limited and may be, for example, particulate, pellet, film, or the like. Among these, a film form is preferred because it allows the formation of a magnetic layer by a lamination method. A film-like resin composition is usually prepared as a resin sheet having a resin composition layer as a film of the resin composition.

[0143] The resin composition layer contains a resin composition, and preferably contains only a resin composition. The thickness of the resin composition layer can be set according to the dimensions of the magnetic substrate to be manufactured. Usually, it is preferable that the resin composition layer is thin. The specific thickness range of the resin composition layer is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 50 μm or more, and preferably 600 μm or less, more preferably 300 μm or less, even more preferably 200 μm or less, and even more preferably 150 μm or less.

[0144] The resin sheet may further include any optional member in combination with the resin composition layer. For example, the resin sheet may include a support that supports the resin composition layer. In a resin sheet including a support, the resin composition layer is usually formed on the support.

[0145] Examples of the support include a film made of a plastic material, a metal foil, and release paper, with a film made of a plastic material and a metal foil being preferred.

[0146] When a film of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylic polymers such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, with inexpensive polyethylene terephthalate being particularly preferred.

[0147] When a metal foil is used as the support, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. The copper foil may be a foil made of a single metal, such as copper, or a foil made of an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0148] The surface of the support that is to be bonded to the resin composition layer may be subjected to a matte treatment, a corona treatment, an antistatic treatment or the like.

[0149] The support may be a support with a release layer having a release layer on the surface that bonds with the resin composition layer. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd-based release agents, polyolefin-based release agents, urethane-based release agents, and silicone-based release agents. Commercially available products may be used as the support with a release layer, and examples include "PET501010," "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation, which are PET films having a release layer primarily composed of a silicone-based release agent or an alkyd resin-based release agent; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; and "Uni-Peel" manufactured by Unitika Ltd.

[0150] The thickness of the support is not particularly limited, but is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more, and is preferably 75 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less. When a support with a release layer is used, it is preferable that the thickness of the entire support with a release layer is in the above range.

[0151] The resin sheet may optionally include a protective film for protecting the resin composition layer. The protective film is usually provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. When a protective film is provided, adhesion of dust and scratches to the surface of the resin composition layer can be suppressed. When a resin sheet including a protective film is used, the protective film is usually peeled off before step (LF).

[0152] The resin sheet can be produced, for example, by a method including forming a resin composition layer on a support. The resin composition layer can be formed, for example, by a method including preparing a resin composition and applying the resin composition to a support. If necessary, an organic solvent may be mixed with the resin composition and then applied to the support. When an organic solvent is used, drying may be performed after application, if necessary.

[0153] The resin composition can be applied using a coating device such as a die coater. Drying can be performed by a drying method such as heating or hot air blowing. The drying conditions are not particularly limited, but the resin composition layer is dried so that the amount of solvent in the layer is preferably 10% by mass or less, more preferably 5% by mass or less. Drying can be performed, for example, at 50°C to 150°C for 3 to 10 minutes, although this may vary depending on the boiling point of the solvent.

[0154] [Step (LF): Formation of Resin Composition Layer] The method for manufacturing a magnetic substrate according to this embodiment may include a step (LF) of forming a resin composition layer prior to the step (EP). In the step (LF), a resin composition layer is typically formed on a suitable substrate. This substrate may hereinafter be referred to as an "inner layer substrate."

[0155] The inner layer substrate may be, for example, a member including a support substrate. Examples of the support substrate include insulating substrates such as glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. Furthermore, the inner layer substrate may be provided with a conductor layer such as a wiring layer or an electrode layer, as needed. In the following description, the conductor layer provided in the inner layer substrate may be referred to as a "substrate conductor layer." The substrate conductor layer may be provided on one side of the support substrate, on both sides, or internally. Examples of the substrate conductor layer include a layer formed of a metal such as copper. Furthermore, the inner layer substrate may have a hole such as a through hole formed therein, as needed. Hereinafter, the hole formed in the inner layer substrate may be referred to as a "first hole." The first hole can be formed by, for example, drilling, laser irradiation, or plasma irradiation. As needed, a substrate conductor layer may be formed on the surface of the inner layer substrate within the first hole.

[0156] There are no limitations on the method for forming a resin composition layer on the inner layer substrate. For example, when a liquid resin composition is used, the resin composition layer may be formed by applying the resin composition to the inner layer substrate. Specific examples include forming the resin composition layer by applying the resin composition to the inner layer substrate using an application device such as a dispenser or a die coater. Alternatively, the resin composition layer may be formed by applying the resin composition to the inner layer substrate by printing such as full-surface printing or pattern printing. Examples of printing methods include printing the resin composition using a squeegee, printing the resin composition using a cartridge, printing the resin composition by mask printing, roll coating, and inkjet printing. Furthermore, if necessary, drying may be performed after application of the resin composition.

[0157] For example, when a resin sheet having a resin composition layer is used, the resin sheet and the inner layer substrate may be laminated so that the resin composition layer is bonded to the inner layer substrate, thereby forming a resin composition layer on the inner layer substrate. The bonding of the resin composition layer and the inner layer substrate can be performed, for example, by thermocompression bonding the resin sheet to the inner layer substrate from the support side. Examples of a member for thermocompression bonding the resin sheet to the inner layer substrate (hereinafter also referred to as a "thermocompression member") include a heated metal plate (such as a stainless steel (SUS) plate) or a metal roll (such as a SUS roll). Note that, rather than pressing the resin sheet in direct contact with the thermocompression member, it is preferable to press the resin sheet via a sheet made of an elastic material such as heat-resistant rubber so that the resin sheet can sufficiently follow the unevenness of the surface of the inner layer substrate.

[0158] The temperature during thermocompression bonding is preferably in the range of 80°C to 160°C, more preferably 90°C to 140°C, and even more preferably 100°C to 120°C. The pressure during thermocompression bonding is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably 0.29 MPa to 1.47 MPa. The time during thermocompression bonding is preferably in the range of 20 seconds to 400 seconds, more preferably 30 seconds to 300 seconds. The resin sheet and the inner layer base material are preferably bonded under reduced pressure conditions of 26.7 hPa or less.

[0159] The resin composition layer of the resin sheet and the inner layer substrate can be bonded using a commercially available vacuum laminator, such as a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd. or a vacuum applicator manufactured by Nikko Materials Co., Ltd.

[0160] After bonding the resin sheet and the inner layer base material, the laminated resin sheet may be smoothed under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the support side. The pressing conditions for the smoothing treatment may be the same as the thermocompression conditions for the lamination. The smoothing treatment may be performed using a commercially available laminator. Note that the lamination and smoothing treatment may be performed consecutively using the commercially available vacuum laminator.

[0161] When a resin sheet having a support is used, the support is usually peeled off after step (LF). The peeling of the support may be performed before step (CU) or after step (CU), but is preferably performed before step (EP).

[0162] When first holes are formed in the inner layer substrate, step (LF) may include forming a resin composition layer in the first holes. Typically, the resin composition is filled into the first holes to form a resin composition layer. For example, a liquid resin composition may be applied to the inner layer substrate in which the first holes are formed, thereby filling the first holes with the resin composition and forming a resin composition layer in the first holes. Alternatively, for example, the inner layer substrate in which the first holes are formed and a resin sheet may be laminated together, thereby filling the first holes with the resin composition and forming a resin composition layer in the first holes.

[0163] [Step (CU): Curing of Resin Composition Layer] The method for producing a magnetic substrate according to this embodiment may include, after step (LF), step (CU) of curing the resin composition layer to form a magnetic layer. Typically, the resin composition layer is thermally cured under specific thermal curing conditions to obtain the magnetic layer. The magnetic layer contains a cured product of the resin composition, and preferably contains only a cured product of the resin composition.

[0164] The thermal curing conditions for the resin composition layer can be appropriately set within the range in which the curing of the resin composition proceeds. The curing temperature is preferably 120°C or higher, more preferably 130°C or higher, and even more preferably 150°C or higher, and preferably 245°C or lower, more preferably 220°C or lower, and even more preferably 200°C or lower. The curing time is preferably 5 minutes or longer, more preferably 10 minutes or longer, and even more preferably 15 minutes or longer, and preferably 120 minutes or shorter, more preferably 110 minutes or shorter, and even more preferably 100 minutes or shorter.

[0165] The method for producing a magnetic substrate according to this embodiment may include a step of heating the resin composition layer at a temperature lower than the curing temperature (preheating step) after forming the resin composition layer and before curing the resin composition layer. For example, prior to curing the resin composition layer, the resin composition layer may be preheated at a temperature of typically 50°C or higher and lower than 150°C (preferably 60°C or higher and 140°C or lower, more preferably 70°C or higher and 130°C or lower) for typically 5 minutes or longer (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes).

[0166] [Step (PO): Polishing] The method for manufacturing a magnetic substrate according to this embodiment may include a step (PO) of polishing the resin composition layer or magnetic layer prior to step (EP). Polishing can smooth the surface of the magnetic layer. For example, when the magnetic layer is polished, the polished surface of the magnetic layer can be planarized. Furthermore, when the resin composition layer is polished, the surface of the resin composition layer can be planarized, and therefore the surface of the magnetic layer obtained by curing the resin composition layer can be planarized. In particular, when a resin composition layer is formed by filling the first holes of an inner layer substrate with a resin composition, excess resin composition may protrude from the first holes or adhere to parts of the inner layer substrate other than the first holes, resulting in unevenness on the surface of the resin composition layer. Therefore, from the viewpoint of removing the unevenness by polishing and improving the surface flatness of the magnetic layer, step (PO) is preferably performed when an inner layer substrate in which first holes are formed is used.

[0167] Examples of the polishing method include buff polishing, belt polishing, ceramic polishing, etc. Examples of commercially available buff polishing devices include "NT-700IM" manufactured by Ishii Hyoki Co., Ltd.

[0168] The arithmetic mean roughness (Ra) of the polished surface of the magnetic layer (after thermal curing of the cured layer) is preferably 300 nm or more, more preferably 350 nm or more, and even more preferably 400 nm or more, from the viewpoint of improving adhesion with the electroplated layer. The upper limit is preferably 1000 nm or less, more preferably 900 nm or less, and even more preferably 800 nm or less. The surface roughness (Ra) can be measured, for example, using a non-contact surface roughness meter.

[0169] When polishing is performed after curing the resin composition layer to obtain a magnetic layer, the magnetic layer may be heat-treated before polishing in order to further increase the degree of curing of the cured product contained in the magnetic layer. The temperature in the heat treatment may be the same as the curing temperature described above. The specific heat treatment temperature is preferably 120°C or higher, more preferably 130°C or higher, and even more preferably 150°C or higher, and preferably 245°C or lower, more preferably 220°C or lower, and even more preferably 200°C or lower. The heat treatment time is preferably 5 minutes or longer, more preferably 10 minutes or longer, and even more preferably 15 minutes or longer, and preferably 90 minutes or shorter, more preferably 70 minutes or shorter, and even more preferably 60 minutes or shorter.

[0170] On the other hand, when polishing is performed before curing the resin composition layer to obtain the magnetic layer, a preheating treatment may be performed before polishing, in which the resin composition layer is heated at a temperature lower than the curing temperature of the resin composition. The temperature in the preheating treatment is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, and preferably 245°C or lower, more preferably 220°C or lower, even more preferably 200°C or lower. The heat treatment time is preferably 5 minutes or longer, more preferably 10 minutes or longer, even more preferably 15 minutes or longer, and preferably 90 minutes or shorter, more preferably 70 minutes or shorter, even more preferably 60 minutes or shorter.

[0171] [Step (HF): Formation of Second Holes] The method for manufacturing a magnetic substrate according to this embodiment may include a step (HF) of forming holes in the magnetic layer prior to step (EP). Holes formed in the magnetic layer may be referred to as "second holes" hereinafter. Typically, the formation of the second holes is carried out after step (CU). Furthermore, the formation of the second holes may be carried out before the polishing in step (PO), but is usually carried out after the polishing in step (PO).

[0172] Examples of the second hole include a via hole and a through hole. For example, when a second hole is formed in a magnetic layer formed in a first hole of an inner layer substrate, the second hole may be a through hole that penetrates the magnetic layer. Furthermore, for example, when a second hole is formed in a magnetic layer formed on the main surface of an inner layer substrate, the second hole may be a via hole that penetrates the magnetic layer but not the inner layer substrate, or may be a through hole that penetrates both the magnetic layer and the inner layer substrate. The second hole can be formed by processing methods such as drilling, laser processing, plasma irradiation, and etching.

[0173] [Step (RO): Roughening Treatment] The method for manufacturing a magnetic substrate according to this embodiment may include step (RO) of roughening the magnetic layer prior to step (EP). Typically, the roughening treatment is performed after step (PO). Also, typically, the roughening treatment is performed after step (HF). The roughening treatment increases the surface roughness of the magnetic layer, thereby enhancing the adhesion strength between the magnetic layer and the electroplated layer. Furthermore, the roughening treatment can remove resin residue (smear) that may result from the formation of the second holes. The roughening treatment may be performed wet, but is preferably performed dry. Examples of dry roughening treatments include plasma treatment.

[0174] [Step (EP): Electroplating] The method for manufacturing a magnetic substrate according to this embodiment includes a step (EP) of forming an electroplated layer as a conductor layer on the surface of the magnetic layer by electroplating. In electroplating, the electroplated layer is typically formed on the surface of the magnetic layer in a plating solution containing metal ions. For example, the magnetic layer and electrodes are placed in the plating solution, and a direct current is applied between the magnetic layer and the electrodes from a power source. Metal ions are reduced on the surface of the magnetic layer, depositing the metal, forming an electroplated layer containing that metal. Copper is preferably used as the metal for electroplating.

[0175] Typically, an aqueous solution of a metal salt is used as the plating solution. There are no limitations on the metal salt as long as it allows the formation of an electroplated layer. For example, when copper is used as the metal, examples of the copper salt include copper sulfate such as copper sulfate pentahydrate, copper halides such as copper chloride, copper acetate, copper nitrate, copper tetrafluoroborate, copper alkylsulfonate, copper arylsulfonate, copper sulfamate, copper perchlorate, and copper gluconate. Among these, copper sulfate is preferred. The concentration of the metal salt in the plating solution can be, for example, 50 g / L or more and 400 g / L or less. It is more preferred that the concentration of the metal salt in the plating solution be a saturated concentration.

[0176] The plating solution preferably contains an acid. Examples of acids include sulfuric acid; hydrochloric acid; acetic acid; nitric acid; phosphoric acid; fluoroboric acid; alkanesulfonic acids such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and trifluoromethanesulfonic acid; arylsulfonic acids such as benzenesulfonic acid, p-toluenesulfonic acid, and sulfamic acid; hydrobromic acid; perchloric acid; and chromic acid. Among these, sulfuric acid, methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, hydrochloric acid, and combinations thereof are preferred, with sulfuric acid being more preferred. The concentration of the acid in the plating solution can be, for example, 1 mL / L or more and 400 mL / L or less. When sulfuric acid is used, the concentration of sulfuric acid is preferably 40 mL / L or more and 200 mL / L or less.

[0177] The plating solution may contain additives. Examples of additives that the plating solution may contain include a halide ion supplier, a brightener, a surfactant, and the like. Examples of halide ion suppliers include chlorine compounds such as sodium chloride and potassium chloride. The concentration of the halide ion supplier in the plating solution may be, for example, 0.5 mg / L or more and 300 mg / L or less. Examples of brighteners include organic sulfur compounds such as bis(3-sulfopropyl)disulfide salts. The concentration of the brightener in the plating solution may be, for example, 0.1 ppm or more and 1000 ppm or less. Examples of surfactants include anionic surfactants, cationic surfactants, and nonionic surfactants. The concentration of the surfactant in the plating solution may be, for example, 1 mL / L or more and 60 mL / L or less.

[0178] The temperature of the plating solution is not limited as long as it can form an electroplated layer, and is preferably 2°C or higher, more preferably 10°C or higher, and even more preferably 15°C or higher, and is preferably 80°C or lower, more preferably 50°C or lower, and even more preferably 30°C or lower.

[0179] The current density of the current applied during electroplating is not limited as long as it is possible to form an electroplated layer, and is preferably 0.5 A / dm ２ More preferably, 1.0 A / dm ２ or more, preferably 8.0 A / dm ２ or less, more preferably 7.0 A / dm ２ The following is the result.

[0180] The electroplating may be performed in a state where a plating solution is allowed to flow. The flow rate of the plating solution may be, for example, 3 cm / sec or more and 200 cm / sec or less.

[0181] The electroplating method described above allows the formation of an electroplated layer directly on the surface of the magnetic layer. The term "directly" used in the context of forming an electroplated layer on the surface of the magnetic layer means that the magnetic layer and the electroplated layer are in contact with each other, with no other layers between them. An interface is formed between the magnetic layer and the electroplated layer in this contact state, but this interface typically lacks a plating catalyst. If a conductive layer were to be formed on the magnetic layer by electroless plating, a plating catalyst such as palladium, gold, silver, or platinum would remain between the magnetic layer and the conductive layer, making the electroplated layer distinguishable from a conductive layer formed by electroless plating by the presence of the plating catalyst.

[0182] According to the electroplating method described above, it is possible to form an electroplated layer without forming a thin conductor layer (seed layer) by electroless plating. Therefore, electroless plating can be omitted, thereby reducing the number of steps in the method for manufacturing a magnetic substrate. From the viewpoint of effectively utilizing this advantage, it is preferable that the method for manufacturing a magnetic substrate according to this embodiment does not include a step of forming a conductor layer on the surface of the magnetic layer by a method other than electroplating between the step (CU) of curing the resin composition layer to form a magnetic layer and the step (EP) of forming an electroplated layer on the surface of the magnetic layer.

[0183] As described above, by not performing electroless plating, chemical solutions for electroless plating are not required, and therefore there is no need to manage the components of the chemical solutions. This makes it possible to shorten the time and simplify the labor required to manufacture a magnetic substrate. Furthermore, while some chemical solutions can dissolve or alter alloys, a manufacturing method that does not use chemical solutions can use (A-1) alloy powder that is dissolved or altered by chemical solutions. This allows for a wider range of options for (A-1) alloy powder, which is expected to lead to greater diversity and sophistication of magnetic substrates.

[0184] When second holes are formed in the magnetic layer, the step (EP) of forming an electroplated layer may include forming an electroplated layer by electroplating on the surface of the second holes in the magnetic layer. From the viewpoint of accelerating the formation of the electroplated layer in the second holes, it is preferable to perform electroplating while the plating solution is flowing so that the plating solution can easily enter the second holes. Furthermore, from the viewpoint of more efficiently forming the electroplated layer in the second holes, a treatment of applying ultrasonic waves to the plating solution may be performed.

[0185] The method for manufacturing a magnetic substrate according to this embodiment may include a step of annealing the magnetic layer and the electroplated layer after electroplating (annealing step). The annealing temperature range is preferably 150°C or higher, more preferably 160°C or higher, even more preferably 170°C or higher, and preferably 260°C or lower, more preferably 250°C or lower, and even more preferably 240°C or lower. The annealing time range is preferably 10 minutes or higher, more preferably 20 minutes or higher, even more preferably 30 minutes or higher, and preferably 10 hours or lower, more preferably 5 hours or lower, and even more preferably 2 hours or lower. The annealing may be performed in an inert atmosphere such as a nitrogen gas atmosphere. The annealing can increase the adhesion strength between the magnetic layer and the electroplated layer.

[0186] By forming an electroplated layer on the surface of the magnetic layer as described above, a magnetic substrate is obtained that includes the magnetic layer and the electroplated layer formed on the surface of this magnetic layer. For example, when the electroplated layer is formed helically by itself, or when the combination of the electroplated layer and any conductive layer provided on the magnetic substrate is formed helically, an inductor can be formed by the conductive layer, such as the electroplated layer and any conductive layer, and therefore an inductor-embedded substrate with an inductor can be obtained as a magnetic substrate.

[0187] The thickness of the electroplated layer is not particularly limited and can be selected from an appropriate range depending on the application. In one example, the thickness of the electroplated layer is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more, and is preferably 70 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less.

[0188] The formed electroplated layer preferably has a small surface roughness. The arithmetic mean roughness Ra of the surface of the electroplated layer is preferably 2000 nm or less, more preferably 1000 nm or less, and even more preferably 800 nm or less. There is no particular lower limit, but it may be 1 nm or more, 10 nm or more, 50 nm or more, etc. The surface roughness of the electroplated layer can be measured using a non-contact surface roughness meter.

[0189] [Optional Step] The method for manufacturing a magnetic substrate according to this embodiment may further include an optional step in combination with the steps described above.

[0190] The method for manufacturing a magnetic substrate may include, for example, a step of forming an optional conductor layer. Specifically, when it is desired to provide an optional conductor layer other than the substrate conductor layer and the electroplated layer on the magnetic substrate, the method for manufacturing a magnetic substrate may include a step of forming the optional conductor layer. Examples of methods for forming the optional conductor layer include plating, sputtering, and vapor deposition. Furthermore, the optional conductor layer may be processed into a desired wiring pattern by an appropriate method such as a semi-additive method or a full-additive method.

[0191] Here, an example of a method for forming an optional conductor layer will be described in detail. A thin conductor layer (seed layer) is formed by electroless plating. Next, a further conductor layer is formed on the formed seed layer by electroplating. Thereafter, if necessary, unnecessary seed layer is removed by a process such as etching, thereby forming an optional conductor layer having a desired wiring pattern. After forming the optional conductor layer, an annealing process may be performed as necessary to improve adhesion strength.

[0192] The method for manufacturing a magnetic substrate may include, for example, a step of forming an optional insulating layer. Specifically, an optional insulating layer may be formed when it is desired to insulate the electroplated layer from other conductive layers. Alternatively, as another specific example, an electroplated layer may be formed on the surface inside the second hole of the magnetic layer, and when the electroplated layer alone is not enough to fill the entire second hole, an insulating layer may be formed to fill the second hole. The insulating layer may be formed from a cured product of a thermosetting resin composition or a photocurable resin composition. Specifically, the insulating layer may be formed by forming a layer of a thermosetting resin composition or a photocurable resin composition on the magnetic substrate and curing the layer.

[0193] The method for manufacturing a magnetic substrate may involve repeatedly forming the magnetic layer and the electroplated layer, as well as forming any conductive layer and any insulating layer. For example, the magnetic layer and the electroplated layer may be repeatedly formed to alternately stack the magnetic layer and the electroplated layer.

[0194] [Magnetic Substrate] The magnetic substrate manufactured by the above-described manufacturing method comprises a magnetic layer and an electroplated layer formed on the surface of the magnetic layer. The structure of the magnetic substrate is not particularly limited as long as it comprises a magnetic layer and an electroplated layer. Therefore, the uses of the magnetic substrate to be manufactured by the above-described manufacturing method are not limited. From the viewpoint of utilizing the fact that an electroplated layer can be formed on the surface of the magnetic layer by electroplating, it is preferable that the magnetic substrate comprises a magnetic layer in which second holes are formed, and an electroplated layer formed in the second holes.

[0195] For example, consider a case where a magnetic layer is formed on the main surface of an inner layer substrate, and a conductor layer is formed on the main surface of the magnetic layer. In this case, it is possible to form an electroplated layer as the conductor layer on the main surface of the magnetic layer using the method described above, but it is also possible to form the conductor layer using a metal foil such as copper foil. Therefore, the conductor layer could be formed without electroless plating by a method other than the method described in the embodiment described above.

[0196] However, when attempting to form a conductor layer in the second hole formed in the magnetic layer, the second hole is generally small, making it difficult to form a conductor layer using metal foil. Therefore, forming a conductor layer in the second hole without using electroless plating cannot be achieved by any method other than the method according to the above-described embodiment.

[0197] Therefore, from the viewpoint of providing a new magnetic substrate that cannot be realized by any method other than the manufacturing method according to the above-described embodiment and effectively utilizing the above-described manufacturing method, it is preferable to manufacture a magnetic substrate including a magnetic layer in which second holes are formed and an electroplated layer formed in the second holes by the above-described manufacturing method. An example of this magnetic substrate will be described below along with its manufacturing method, with reference to the drawings. However, the magnetic substrate and its manufacturing method are not limited to the example shown below.

[0198] 1 to 12 are schematic cross-sectional views illustrating each step of a method for manufacturing a magnetic substrate according to one example. The method for manufacturing a magnetic substrate according to this example includes the step of preparing an inner layer base material 10, as shown in Figure 1. This example will be described by showing a plate-shaped inner layer base material 10 that includes a support substrate 11 and base conductor layers 12 formed on both sides of this support substrate 11.

[0199] After preparing the inner layer base material 10, the method for manufacturing a magnetic substrate according to this example includes the step of forming first holes 10H as through holes in the inner layer base material 10, as shown in Figure 2. The first holes 10H are formed so as to penetrate the inner layer base material 10 in the thickness direction. There are no particular restrictions on the diameter of the first holes 10H, and they can be, for example, 200 μm to 800 μm.

[0200] After forming the first holes 10H, the manufacturing method of the magnetic substrate according to this example includes a step (step (LF)) of forming a resin composition layer 20 in the first holes 10H of the inner layer base material 10, as shown in Fig. 3. Usually, when the resin composition layer 20 is formed in the first holes 10H, excess resin composition protrudes or adheres to the outside of the first holes 10H. Therefore, the main surfaces 20U and 20D of the resin composition layer 20 formed at the openings of the first holes 10H are often raised and not flat.

[0201] After forming the resin composition layer 20, the manufacturing method of the magnetic substrate according to this example includes a step of polishing the resin composition layer 20, as shown in Figure 4 (step (PO)). By polishing, excess resin composition protruding or adhering to the outside of the first holes 10H is removed, making it possible to flatten the main surfaces 20U and 20D of the resin composition layer 20. Typically, after polishing, the main surface 20U of the resin composition layer 20 will be flush with one main surface 10U of the inner layer base material 10, and the main surface 20D of the resin composition layer 20 will be flush with the other main surface 10D of the inner layer base material 10. Unless otherwise specified, "flush" of multiple surfaces means that those surfaces are in the same plane.

[0202] 5, after forming the resin composition layer 20, the method for manufacturing a magnetic substrate according to this example includes a step (step (CU)) of curing the resin composition layer 20 to obtain the magnetic layer 30. Here, an example is shown in which the curing is performed after polishing the resin composition layer 20, but polishing of the magnetic layer 30 may also be performed after curing the resin composition layer 20 to obtain the magnetic layer 30.

[0203] After forming the magnetic layer 30, the method for manufacturing a magnetic substrate according to this example includes a step (step (HF)) of forming second holes 30H as through holes in the magnetic layer 30, as shown in Fig. 6. The second holes 30H are formed so as to penetrate the magnetic layer 30 in the thickness direction. The diameter of the second holes 30H can be smaller than the diameter of the first holes 10H, and there is no limit to the specific size thereof.

[0204] After forming the second holes 30H, the manufacturing method for the magnetic substrate according to this example includes a step (step (EP)) of forming an electroplated layer 40 on the surface 30S of the magnetic layer 30, as shown in Figure 7. The surface 30S of the magnetic layer 30 that is not joined to the inner layer base material 10 includes main surfaces 30U and 30D formed at the openings of the first holes 10H, and hole inner surfaces 30I formed within the second holes 30H. The electroplated layer 40 is usually formed on both the main surfaces 30U and 30D of the magnetic layer 30 and the hole inner surfaces 30I.

[0205] The second hole 30H may be entirely filled with the electroplated layer 40, but a portion of the second hole 30H may not be filled. When a portion of the second hole 30H is not filled with the electroplated layer 40, the method for manufacturing a magnetic substrate according to this example may include a step of forming an insulating layer 50 in the portion of the electroplated layer 40 that is not filled with the electroplated layer 40, as shown in Fig. 8. The insulating layer 50 can be formed by filling the portion with a curable resin, such as a thermosetting resin composition or a photocurable resin composition, and curing the resin.

[0206] After the insulating layer 50 is formed, the insulating layer 50 may be polished. When polishing the insulating layer 50, the electroplated layer 40 may also be polished at the same time. Here, an example will be described in which the insulating layer 50 and the electroplated layer 40 are polished, as shown in FIG. 9 . In this example, the polishing results in the main surface 10U of the inner layer base material 10, the main surface 30U of the magnetic layer 30, the main surface 40U of the electroplated layer 40, and the main surface 50U of the insulating layer 50 being flush with each other. Furthermore, the main surface 10D of the inner layer base material 10, the main surface 30D of the magnetic layer 30, the main surface 40D of the electroplated layer 40, and the main surface 50D of the insulating layer 50 are flush with each other.

[0207] After forming the electroplated layer 40, the manufacturing method of the magnetic substrate according to this example may include a step of forming an optional conductor layer 60 on the inner layer base material 10, magnetic layer 30, electroplated layer 40, and insulating layer 50, as shown in Fig. 10. The optional conductor layer 60 can be formed by, for example, electroless plating and electroplating. Thereafter, as shown in Fig. 11, an etching resist 70 having a desired pattern is formed on the optional conductor layer 60. Then, portions of the base material conductor layer 12, the electroplated layer 40, and the optional conductor layer 60 that are not covered by the etching resist 70 are removed, and the etching resist 70 is then removed.

[0208] Fig. 12 is a schematic cross-sectional view of a magnetic substrate according to one example. The above steps make it possible to obtain the magnetic substrate 100 shown in Fig. 12. At this time, by forming the conductor layers, such as the substrate conductor layer 12, the electroplated layer 40, and the optional conductor layer 60, in a helical shape as a whole, an inductor can be formed by the conductor layers, and therefore an inductor-embedded substrate can be obtained as the magnetic substrate 100. Furthermore, in the manufacturing method according to this example, further conductor layers other than the substrate conductor layer 12, the electroplated layer 40, and the optional conductor layer 60 may be provided.

[0209] As shown in FIG. 12 , the magnetic substrate 100 includes a magnetic layer 30 having a second hole 30H formed therein and an electroplated layer 40 formed on the surface 30S of the magnetic layer 30. In this example, at least a portion of the electroplated layer 40 is formed within the second hole 30H. Because the electroplated layer 40 is formed without electroless plating, the electroplated layer 40 formed within the second hole 30H and the magnetic layer 30 are in direct contact. Furthermore, the interface between the electroplated layer 40 and the magnetic layer 30 (corresponding to the hole inner surface 30I) is free of a plating catalyst for electroless plating. Forming a conductor layer on the surface of a magnetic layer within a second hole formed in the magnetic layer without the use of a plating catalyst has not been achieved in conventional technology. Therefore, the magnetic substrate 100 described above is not only unprecedented in its manufacturing method but also in its structure.

[0210] The above-described magnetic substrate can be used, for example, in the manufacture of an inductor component. This inductor component includes the above-described magnetic substrate. The inductor component typically has an inductor pattern formed by conductor layers, such as a substrate conductor layer, an electroplated layer, and an optional conductor layer, at least partially around the periphery of the magnetic layer. For example, the inductor component described in JP 2016-197624 A can be applied to such an inductor component. The inductor component includes the above-described inductor-embedded substrate.

[0211] The inductor component can be used, for example, as a wiring board for mounting electronic components such as semiconductor chips, or as a (multilayer) printed wiring board using such a wiring board as an inner layer substrate.Furthermore, for example, such a wiring board can be singulated and used as a chip inductor component, or as a surface-mounted printed wiring board.

[0212] Furthermore, such a wiring board can be used to manufacture various types of semiconductor devices. Semiconductor devices including such wiring boards can be suitably used in electrical products (e.g., computers, mobile phones, digital cameras, televisions, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, aircraft, etc.).

[0213] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Furthermore, unless otherwise specified, the operations described below were carried out at room temperature and atmospheric pressure (23°C, 1 atmosphere). Furthermore, the volume content (volume %) was calculated using the mass and specific gravity.

[0214] Example 1: Production of magnetic varnish 1 1.92 parts by mass of epoxy resin ("ZX-1059" manufactured by Nippon Steel Chemical & Material Co., Ltd., a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, epoxy equivalent 169 g / eq.), 2.18 parts by mass of triazine skeleton-containing phenolic resin ("LA-7054" manufactured by DIC Corporation, MEK solution with a solid content of 60% and a hydroxyl group equivalent of approximately 125 g / eq.), phenoxy resin ( Mitsubishi Chemical Corporation's "YL7553BH30" (1:1 solution of MEK and cyclohexanone with a solid content of 30%) 1.67 parts by mass, dispersant (Ajinomoto Fine-Techno Co., Ltd.'s "PB-821" cationic dispersant) 0.43 parts by mass, solvent (cyclohexanone) 3 parts by mass, ferrite powder (Powder Tech Co., Ltd.'s "M03S" Fe-Mn ferrite, average particle size 0.5 μm, specific gravity 5.1 m ２ / g) 22.09 parts by mass, and alloy powder ("AKT-PB (5)" manufactured by Mitsubishi Steel Corporation, Fe-Ni alloy, average particle size 5.0 μm, specific gravity 8.0 m ２ 73.74 parts by mass of the above powder (1 / g) were mixed together to prepare magnetic varnish 1.

[0215] Example 2: Production of magnetic varnish 2 Ferrite powder ("M03S" manufactured by Powder Tech Co., Ltd., Fe-Mn ferrite, average particle size 0.5 μm, specific gravity 5.1 m) ２ The amount of alloy powder ("AKT-PB (5)" manufactured by Mitsubishi Steel Corporation, Fe-Ni alloy, average particle size 5.0 μm, specific gravity 8.0 m ２ The amount of cellulose acetate (wt. / g) was changed from 73.74 parts by mass to 30.00 parts by mass. Magnetic varnish 2 was produced in the same manner as in Example 1 except for the above points.

[0216] Example 3: Production of magnetic varnish 3 Ferrite powder ("M03S" manufactured by Powder Tech Co., Ltd., Fe-Mn ferrite, average particle size 0.5 μm, specific gravity 5.1 m) ２ The amount of alloy powder ("AKT-PB (5)" manufactured by Mitsubishi Steel Corporation, Fe-Ni alloy, average particle size 5.0 μm, specific gravity 8.0 m ２ / g) was changed from 73.74 parts by mass to 22.00 parts by mass. Magnetic varnish 3 was produced in the same manner as in Example 1 except for the above points.

[0217] Example 4: Production of magnetic varnish 4 Ferrite powder ("M03S" manufactured by Powder Tech Co., Ltd., Fe-Mn ferrite, average particle size 0.5 μm, specific gravity 5.1 m) ２ 22.09 parts by mass of alloy powder (fine powder alloy "CVD iron powder" manufactured by JFE Mineral Co., Ltd., Fe-Cr-Si alloy, average particle size 0.7 μm, specific gravity 6.9 m ２ Magnetic varnish 4 was produced in the same manner as in Example 1, except that the amount of the cellulose ester compound (C10) was changed to 30.92 parts by mass ( / g).

[0218] Example 5: Production of magnetic varnish 5 Ferrite powder ("M03S" manufactured by Powder Tech Co., Ltd., Fe-Mn ferrite, average particle size 0.5 μm, specific gravity 5.1 m) ２22.09 parts by mass of ferrite powder ("MZ03S" manufactured by Powder Tech Co., Ltd., Fe-Mn-Zn ferrite, average particle size 0.5 μm, specific gravity 5.1 m) was added. ２ Magnetic varnish 5 was produced in the same manner as in Example 1, except that the amount of the cellulose ester was changed to 22.09 parts by mass (1 / g).

[0219] Example 6: Production of magnetic varnish 6 Alloy powder ("AKT-PB (5)" manufactured by Mitsubishi Steel Corporation, Fe-Ni alloy, average particle size 5.0 μm, specific gravity 8.0 m ２ / g) 73.74 parts by mass of alloy powder ("AKT-PB-3Si(5)" manufactured by Mitsubishi Steel Corporation, Fe-Ni-Si alloy, average particle size 5.0 μm, specific gravity 8.0 m ２ Magnetic varnish 6 was produced in the same manner as in Example 1, except that the amount of the cellulose ester was changed to 73.74 parts by mass ( / g).

[0220] Example 7: Production of magnetic varnish 7 Alloy powder ("AKT-PB (5)" manufactured by Mitsubishi Steel Corporation, Fe-Ni alloy, average particle size 5.0 μm, specific gravity 8.0 m ２ 73.74 parts by mass of alloy powder (Epson Atmix "AW2-08 PF3F", Fe-Si-Cr alloy, average particle size 3.0 μm, specific gravity 6.9 m ２ Magnetic varnish 7 was produced in the same manner as in Example 1, except that the amount of the magnetic powder was changed to 50.00 parts by mass ( / g).

[0221] Example 8: Production of magnetic paste 8 1.70 parts by mass of epoxy resin ("ZX-1059" manufactured by Nippon Steel Chemical & Material Co., Ltd., a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, epoxy equivalent 169 g / eq.), 1.42 parts by mass of epoxy resin ("630" manufactured by Mitsubishi Chemical Corporation, glycidylamine type epoxy resin, epoxy equivalent 95 g / eq.), 1.42 parts by mass of epoxy resin ("ZX-1658GS" manufactured by Nippon Steel Chemical & Material Co., Ltd., a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, epoxy equivalent 169 g / eq.), aliphatic diglycidyl ether, epoxy equivalent 135 g / eq.), 4.90 parts by mass, dispersant (Ajinomoto Fine-Techno Co., Inc. "PB-821", cationic dispersant), 0.57 parts by mass, curing accelerator (Shikoku Chemicals Co., Ltd. "2MZA-PW", imidazole-based epoxy resin curing accelerator), 0.47 parts by mass, ferrite powder (Powder Tech Co., Ltd. "M03S", Fe-Mn-based ferrite, average particle size 0.5 μm, specific gravity 5.1 m), ２ / g) 17.75 parts by mass, and alloy powder ("AKT-PB (5)" manufactured by Mitsubishi Steel Corporation, Fe-Ni alloy, average particle size 5.0 μm, specific gravity 8.0 m ２ 59.09 parts by mass of the magnetic paste (1 / g) were mixed together to prepare magnetic paste 8.

[0222] Example 9: Production of magnetic ink 9 4.6 parts by mass of epoxy resin ("ZX-1059" manufactured by Nippon Steel Chemical & Material Co., Ltd., a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, epoxy equivalent 169 g / eq.), 1.42 parts by mass of epoxy resin ("630" manufactured by Mitsubishi Chemical Corporation, glycidyl amine type epoxy resin, epoxy equivalent 95 g / eq.), 1.42 parts by mass of epoxy resin ("ZX-1658GS" manufactured by Nippon Steel Chemical & Material Co., Ltd., cycloaliphatic diglyceride), 2.0 parts by mass of hydroxybenzoyl ether (epoxy equivalent 135 g / eq.), 0.57 parts by mass of dispersant (Ajinomoto Fine-Techno Co., Inc. "PB-821", cationic dispersant), 0.47 parts by mass of curing accelerator (Shikoku Chemicals Co., Ltd. "2MZA-PW", imidazole-based epoxy resin curing accelerator), 1.0 part by mass of solvent (butyl carbitol acetate), 1.0 part by mass of ferrite powder ("MO3S", Fe-Mn-based ferrite, average particle size 0.5 μm, specific gravity 5.1 m ２ / g, manufactured by Powder Tech Co., Ltd.) 17.75 parts by mass, and alloy powder ("AKT-PB (5)" manufactured by Mitsubishi Steel Corporation, Fe-Ni alloy, average particle size 5.0 μm, specific gravity 8.0 m ２ 59.09 parts by mass of the magnetic ink (1 / g) were mixed together to prepare magnetic ink 9.

[0223] Comparative Example 1: Production of Magnetic Varnish 10 Ferrite powder ("M03S" manufactured by Powder Tech Co., Ltd., Fe-Mn ferrite, average particle size 0.5 μm, specific gravity 5.1 m) ２ The amount of alloy powder ("AKT-PB (5)" manufactured by Mitsubishi Steel Corporation, Fe-Ni alloy, average particle size 5.0 μm, specific gravity 8.0 m ２ The content of hydroxybenzoates (1 / g) was changed from 73.74 parts by mass to 8.00 parts by mass. Furthermore, 3 parts by mass of the solvent (cyclohexanone) was not used. A magnetic varnish 10 was produced in the same manner as in Example 1 except for the above points.

[0224] <Production of Resin Sheet> A PET film ("Lumirror R80" manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130°C, hereinafter sometimes referred to as "release PET") that had been release-treated with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation) was prepared as a support. Resin varnishes 1 to 7 and 10 produced in Examples 1 to 7 and Comparative Example 1 were applied onto this support using a die coater so that the thickness of the resin composition layer after drying was 100 μm, and the resulting film was dried at 65°C to 115°C (average 100°C) for 7 minutes to obtain a resin sheet.

[0225] <Electroplating Test 1: Formation of Conductive Layer by Electroplating Using Resin Sheet> As an inner layer substrate, a glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.3 mm, "R5715ES" manufactured by Panasonic Corporation) was prepared by etching both sides by 1 μm with a microetching agent ("CZ8100" manufactured by MEC Co., Ltd.) to roughen the copper surface.

[0226] A 200 mm square sheet piece was cut from each resin sheet produced in Examples 1 to 7 and Comparative Example 1. The cut sheet piece (200 mm square) was laminated on both sides of the inner layer substrate using a batch-type vacuum pressure laminator (a two-stage build-up laminator "CVP700" manufactured by Nikko Materials Co., Ltd.) so that the resin composition layer was in contact with the center of the inner layer substrate. Lamination was performed by reducing the pressure for 30 seconds to 13 hPa or less, and then pressing at 100 ° C and a pressure of 0.74 MPa for 30 seconds. The resin composition layer was then heat-cured by heating at 130 ° C for 30 minutes and then at 180 ° C for 30 minutes to form a magnetic layer. The surface of the formed magnetic layer was then buffed.

[0227] The polished surface of the magnetic layer was subjected to copper sulfate electroplating. This electroplating was carried out using the magnetic layer as the cathode and a copper plate as the anode in a copper sulfate solution at a current density of 2.0 A / dm ２ The plating solution had the following composition: Copper sulfate pentahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) 79 g / L Sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd.) 154 mL / L Sodium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) 65 mg / L Additive Cupracid HL (manufactured by Atotech Japan), surfactant 30 mL / L Correction Cupracid GS (manufactured by Atotech Japan), organic sulfur compound 0.1 mL / L

[0228] After the electroplating, an annealing treatment was carried out at 180°C for 60 minutes to obtain an evaluation substrate. The evaluation substrate was observed to determine whether or not a conductor layer (electroplated layer) was formed on the surface of the magnetic layer. Those in which an electroplated layer was formed on the entire surface of the magnetic layer were rated as "good," and those in which an electroplated layer was not formed were rated as "poor."

[0229] <Electroplating Test 2: Formation of Conductive Layer by Electroplating Using Magnetic Paste or Magnetic Ink> As an inner layer substrate, a glass cloth-based epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.3 mm, "R5715ES" manufactured by Panasonic Corporation) was prepared by etching both sides by 1 μm with a microetching agent ("CZ8100" manufactured by MEC Co., Ltd.) to roughen the copper surface.

[0230] The magnetic paste produced in Example 8 and the magnetic ink produced in Example 9 were uniformly applied to the inner layer substrate with a doctor blade so that the thickness of the magnetic layer after curing was 100 μm, forming a resin composition layer. The resin composition layer was thermally cured by heating at 130° C. for 30 minutes and then at 150° C. for 30 minutes to form a magnetic layer. The surface of the formed magnetic layer was buffed, and then heat-treated by heating at 180° C. for 30 minutes to further promote curing.

[0231] The polished surface of the magnetic layer was electroplated with copper sulfate electroplating. This electroplating was performed using the same method as in Electroplating Test 1 described above. After electroplating, an annealing treatment was performed at 180°C for 60 minutes to obtain an evaluation substrate. This evaluation substrate was observed to determine whether or not a conductor layer (electroplated layer) was formed on the surface of the magnetic layer. Those in which an electroplated layer was formed over the entire surface of the magnetic layer were rated as "good," and those in which an electroplated layer was not formed were rated as "poor."

[0232] <Magnetic Property Test 1: Measurement of Relative Permeability and Loss Factor of Magnetic Layer Obtained from Resin Sheet> A 200 mm square sheet piece was cut from each resin sheet produced in Examples 1 to 7 and Comparative Example 1. The cut sheet piece (200 mm square) was laminated to one side of a polyimide film (Ube Industries, Ltd., "Upilex 25S," 25 μm thick, 240 mm square) using a batch-type vacuum pressure laminator (Nikko Materials Co., Ltd., two-stage build-up laminator "CVP700"). The lamination was performed so that the resin composition layer of the sheet piece was in contact with the center of the smooth surface of the polyimide film. The lamination was also performed by reducing the pressure for 30 seconds to 13 hPa or less, followed by pressure bonding at 100°C and a pressure of 0.74 MPa for 30 seconds. A multilayer film having a layer structure of support / resin composition layer / polyimide film was obtained by lamination.

[0233] After peeling off the support, the resin composition layer was heat-cured by heating at 190°C for 90 minutes. Thereafter, the polyimide film was peeled off to obtain a sheet-like cured product. This cured product corresponds to the magnetic layer obtained from the resin sheet. The obtained sheet-like cured product was cut to obtain a doughnut-shaped evaluation sample with an outer diameter of 19.2 mm and an inner diameter of 8.2 mm. The relative permeability (μ') and loss factor (tanδ) of this evaluation sample were measured at a measurement frequency of 20 MHz and a room temperature of 23°C using a Keysight magnetic material test fixture "16454A" and a Keysight impedance analyzer "E4991B". The loss factor tanδ was calculated using the following formula "tanδ = μ'' / μ'".

[0234] <Magnetic Property Test 2: Measurement of Relative Permeability and Loss Factor of Magnetic Layer Obtained from Magnetic Paste or Magnetic Ink> A polyethylene terephthalate (PET) film ("PET501010" manufactured by Lintec Corporation, thickness 50 μm) treated with a silicone-based release agent was prepared as a support. The magnetic paste produced in Example 8 and the magnetic ink produced in Example 9 were uniformly applied to the release surface of the PET film using a doctor blade so that the thickness of the magnetic layer after curing was 100 μm, thereby obtaining a resin sheet comprising a support and a resin composition layer.

[0235] The obtained resin sheet was heated at 190°C for 90 minutes to thermally cure the resin composition layer. The support was then peeled off to obtain a sheet-like cured product. This cured product corresponds to the magnetic layer obtained from the magnetic paste or magnetic ink. The obtained sheet-like cured product was cut to obtain a doughnut-shaped evaluation sample with an outer diameter of 19.2 mm and an inner diameter of 8.2 mm. The relative permeability (μ') and loss factor (tanδ) of this evaluation sample were measured at a measurement frequency of 20 MHz and a room temperature of 23°C using a Keysight magnetic material test fixture "16454A" and a Keysight impedance analyzer "E4991B". The loss factor tanδ was calculated using the following formula: "tanδ = μ'' / μ'".

[0236] <Resistance Measurement Test: Measurement of Volume Resistivity of Magnetic Layer> A sheet-like cured product was obtained using the same method as in Magnetic Property Tests 1 and 2. The obtained sheet-like cured product was cut into a 10 cm square evaluation sample. The volume resistivity of this sample was measured using an insulation resistance meter "R8340" manufactured by Advantest Corporation.

[0237] <Surface Roughness Measurement Test: Measurement of Surface Roughness of Electroplated Layer> The arithmetic mean roughness Ra of the electroplated layers formed in the above-described electroplating test 1 and electroplating test 2 was determined using a non-contact surface roughness meter (WYKO NT3300 manufactured by Veeco Instruments) in VSI mode with a 50x lens, with a measurement range of 121 μm × 92 μm, as the Ra value. Each measurement was performed by calculating the average value of 10 randomly selected points.

[0238] <Results> The results of the above-mentioned Examples and Comparative Examples are shown in the table below. In the table below, the meanings of the abbreviations are as follows. CH: cyclohexanone. BCA: butyl carbitol acetate. Amount of magnetic powder (wt%): The amount of (A) magnetic powder relative to 100% by mass of the non-volatile components of the resin composition. Amount of magnetic powder (vol%): The amount of (A) magnetic powder relative to 100% by volume of the non-volatile components of the resin composition. Amount of alloy powder (wt%): The amount of (A-1) alloy powder relative to 100% by mass of the non-volatile components of the resin composition. Amount of alloy powder (vol%): The amount of (A-1) alloy powder relative to 100% by volume of the non-volatile components of the resin composition. Alloy powder / magnetic powder (wt%): The amount of (A-1) alloy powder relative to 100% by mass of the (A) magnetic powder. Alloy powder / magnetic powder (vol%): The amount of (A-1) alloy powder relative to 100% by volume of the (A) magnetic powder. Plating formation: Whether an electroplated layer can be formed by electroplating. Relative permeability: Relative permeability of a cured product of a resin composition corresponding to a magnetic layer. Loss coefficient: Loss coefficient of a cured product of a resin composition corresponding to a magnetic layer. Volume resistivity: Volume resistivity of the magnetic layer. Surface roughness: Surface roughness of the electroplated layer.

[0239]

[0240]

[0241] REFERENCE SIGNS LIST 10 Inner layer substrate 10H First hole 10U, 10D Main surface of inner layer substrate 11 Support substrate 12 Substrate conductor layer 20 Resin composition layer 20U, 20D Main surface of resin composition layer 30 Magnetic layer 30H Second hole 30S Surface of magnetic layer 30U, 30D Main surface of magnetic layer 30I Inner surface of hole of magnetic layer 40 Electroplated layer 50 Insulating layer 60 Optional conductor layer 70 Etching resist 100 Magnetic substrate

Claims

1. A method for manufacturing a magnetic substrate comprising a magnetic layer and a conductive layer formed on the surface of the magnetic layer, comprising a step (EP) of forming the conductive layer on the surface of the magnetic layer by electroplating, wherein the magnetic layer comprises a cured product of a resin composition comprising (A) a magnetic powder and (B) a thermosetting resin, and the (A) magnetic powder comprises 30% by mass or more of an (A-1) alloy powder relative to 100% by mass of the (A) magnetic powder.

2. A method for manufacturing a magnetic substrate as described in claim 1, comprising, prior to step (EP), a step (LF) of forming a resin composition layer containing a resin composition, and a step (CU) of curing the resin composition layer to form a magnetic layer.

3. The method for producing a magnetic substrate according to claim 2, which does not include a step of forming a conductive layer on the surface of the magnetic layer by a method other than electroplating between steps (CU) and (EP).

4. The method for producing a magnetic substrate according to claim 2, wherein step (LF) comprises forming a resin composition layer in the first holes of a substrate in which the first holes have been formed.

5. A method for producing a magnetic substrate according to claim 1, comprising, prior to step (EP), a step (HF) of forming a second hole in the magnetic layer, and step (EP) comprising forming a conductor layer by electroplating on the surface of the magnetic layer within the second hole.

6. The method for producing a magnetic substrate according to claim 1, wherein the amount of the magnetic powder (A) relative to 100% by mass of the nonvolatile components in the resin composition is 60% by mass or more.

7. The method for producing a magnetic substrate according to claim 1, wherein the cured product has a relative magnetic permeability of 10 or more at a measurement frequency of 20 MHz.

8. A method for producing a magnetic substrate according to claim 1, wherein the alloy powder (A-1) includes at least one type selected from the group consisting of Fe-Ni alloy powder, Fe-Cr-Si alloy powder, and Fe-Ni-Cr alloy powder.

9. A magnetic substrate comprising a magnetic layer having holes formed therein and a conductor layer formed in the holes, wherein the magnetic layer and the conductor layer are in direct contact with each other and there is no plating catalyst at the interface between the magnetic layer and the conductor layer, the magnetic layer comprises a cured product of a resin composition containing (A) magnetic powder and (B) a thermosetting resin, and the (A) magnetic powder comprises 30% by mass or more of (A-1) alloy powder relative to 100% by mass of the (A) magnetic powder.

10. The magnetic substrate according to claim 9, wherein the conductor layer is formed of copper.