resin composition

Abstract

To provide a resin composition with low melt viscosity that yields a cured product with high relative permeability and low magnetic loss.SOLUTION: A resin composition comprises (A) Fe-Ni-Si-Cr alloy magnetic powder and (B) thermosetting resin. The Cr content in the component (A) is 0.1 mass% or more and 6 mass% or less relative to 100 mass% of the component (A).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, and a cured product, a magnetic paste, a resin sheet, a circuit board, and an inductor board using the resin composition. [Background technology]

[0002] A cured product obtained by curing a resin composition containing magnetic powder is sometimes used as the core material for inductor components. FeNi alloy powder has been used as the magnetic powder (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-178254 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, it has been common to mount independent inductor components on the substrate of a semiconductor device. However, in recent years, a method has been adopted in which a coil is formed using a conductor pattern on the substrate and an inductor element is provided inside the substrate. To further improve the performance of inductor elements used in such applications, there is a demand for further improvement in the magnetic properties of the core material. Furthermore, if the substrate of a semiconductor device has holes, the holes may be filled with a resin composition containing magnetic powder. In this case, the resin composition is required to have a low melt viscosity.

[0005] The present invention has been made in view of the above-mentioned problems, and aims to provide a resin composition having a low melt viscosity, which is capable of giving a cured product having high relative permeability and low magnetic loss; a cured product of the resin composition; a magnetic paste and resin sheet containing the resin composition; and a circuit board and inductor board containing the cured product of the resin composition. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by a resin composition containing (A) an Fe-Ni-Si-Cr based alloy magnetic powder containing specific amounts of Si and Cr in combination with (B) a thermosetting resin, thereby completing the present invention.

[0007] That is, the present invention includes the following. [1] (A) Fe-Ni-Si-Cr alloy magnetic powder, and (B) a thermosetting resin, A resin composition, wherein the Cr content of component (A) is 0.1% by mass or more and 6% by mass or less, relative to 100% by mass of component (A). [2] The resin composition according to [1], further comprising (C) a magnetic powder other than the Fe—Ni—Si—Cr-based alloy magnetic powder. [3] The resin composition according to [2], wherein component (C) contains a ferrite-based magnetic powder. [4] The resin composition according to [2] or [3], wherein the component (C) contains a ferrite-based magnetic powder containing at least one element selected from the group consisting of Mn, Zn, Ni, and Cu. [5] The resin composition according to any one of [2] to [4], wherein the component (C) has an average particle size smaller than that of the component (A). [6] The resin composition according to any one of [1] to [5], wherein the component (B) contains an epoxy resin (B-1). [7] The resin composition according to any one of [1] to [6], wherein the component (B) contains a curing agent (B-2). [8] The resin composition according to any one of [1] to [7], further comprising (E) a dispersant. [9] The resin composition according to any one of [1] to [8], further comprising (F) a curing accelerator.

[10] The resin composition according to any one of [1] to [9], wherein the content of Si contained in component (A) is 0.2% by mass or more and 5% by mass or less, relative to 100% by mass of component (A).

[11] The resin composition according to any one of [1] to

[10] , wherein the Cr content in component (A) is 0.5% by mass or more and 6% by mass or less, relative to 100% by mass of component (A).

[12] The resin composition according to any one of [1] to

[11] , wherein the amount of component (A) is 40% by mass or more relative to 100% by mass of the nonvolatile components in the resin composition.

[13] The resin composition according to any one of [1] to

[12] , wherein the amount of component (A) is 30% by volume or more relative to 100% by volume of the nonvolatile components in the resin composition.

[14] The resin composition according to any one of [2] to

[13] , wherein the total amount of the components (A) and (C) is 70% by mass or more relative to 100% by mass of the nonvolatile components in the resin composition.

[15] The resin composition according to any one of [2] to

[14] , wherein the total amount of the components (A) and (C) is 50% by volume or more relative to 100% by volume of the nonvolatile components in the resin composition.

[16] The resin composition according to any one of [1] to

[15] , which is for hole filling.

[17] A cured product of the resin composition according to any one of [1] to

[16] .

[18] A magnetic paste comprising the resin composition according to any one of [1] to

[16] .

[19] A support and a resin composition layer provided on the support, A resin sheet, wherein a resin composition layer contains the resin composition according to any one of [1] to

[16] .

[20] A circuit board comprising: a substrate having holes; and a cured product of the resin composition according to any one of [1] to

[16] filled in the holes.

[21] A circuit board comprising a cured product layer containing a cured product of the resin composition according to any one of [1] to

[16] .

[22] An inductor substrate comprising the circuit board according to

[20] or

[21] . [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a resin composition having a low melt viscosity and capable of producing a cured product having high relative magnetic permeability and low magnetic loss; a cured product of the resin composition; a magnetic paste and a resin sheet containing the resin composition; and a circuit board and an inductor board containing the cured product of the resin composition. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a core substrate prepared in a method for manufacturing a circuit board according to a first example of one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view that schematically shows a core substrate in which a through-hole is formed, in a method for manufacturing a circuit board according to a first example of one embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view that schematically shows a core substrate in which a plating layer has been formed in a through-hole in a method for manufacturing a circuit board according to a first example of one embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view that schematically shows how the through-holes of the core substrate are filled with a resin composition in a method for manufacturing a circuit board according to a first example of one embodiment of the present invention. [Figure 5] FIG. 5 is a schematic cross-sectional view illustrating step (2) of the method for manufacturing a circuit board according to a first example of one embodiment of the present invention. [Figure 6] FIG. 6 is a schematic cross-sectional view illustrating step (3) of the method for manufacturing a circuit board according to a first example of one embodiment of the present invention. [Figure 7] FIG. 7 is a schematic cross-sectional view illustrating step (5) of the method for manufacturing a circuit board according to a first example of one embodiment of the present invention. [Figure 8] FIG. 8 is a schematic cross-sectional view illustrating step (5) of the method for manufacturing a circuit board according to a first example of one embodiment of the present invention. [Figure 9] FIG. 9 is a schematic cross-sectional view illustrating step (i) in a method for producing a circuit board according to a second example of one embodiment of the present invention. [Figure 10] FIG. 10 is a schematic cross-sectional view illustrating step (i) in a method for producing a circuit board according to a second example of one embodiment of the present invention. [Figure 11] FIG. 11 is a schematic cross-sectional view illustrating step (ii) in a method for producing a circuit board according to a second example of one embodiment of the present invention. [Figure 12] FIG. 12 is a schematic cross-sectional view illustrating step (iv) in the method for producing a circuit board according to a second example of one embodiment of the present invention. [Figure 13] FIG. 13 is a schematic plan view of the circuit board of the inductor substrate as viewed from one side in the thickness direction. [Figure 14] FIG. 14 is a schematic diagram showing a cut end surface of the circuit board cut at the position indicated by the dashed line II-II in FIG. [Figure 15] FIG. 15 is a schematic plan view illustrating the configuration of a first conductor layer of a circuit board included in the inductor substrate. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention will be described in detail below with reference to preferred embodiments thereof. 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.

[0011] In the following description, the "resin component" of the resin composition refers to the non-volatile components contained in the resin composition excluding inorganic particles such as magnetic powder.

[0012] In the following description, "magnetic permeability" refers to "relative magnetic permeability" unless otherwise specified.

[0013] <Resin composition> The resin composition of the present invention comprises (A) an Fe-Ni-Si-Cr alloy magnetic powder and (B) a thermosetting resin, and the Cr content of component (A) is 0.1% by mass to 6% by mass, based on 100% by mass of component (A). This resin composition has a low melt viscosity, and the cured product of the resin composition can have a high relative magnetic permeability and low magnetic loss.

[0014] The present inventors speculate as follows about the mechanism by which such excellent effects are obtained by the resin composition according to the present embodiment. Generally, FeNi alloys have a crystalline structure formed by Fe and Ni, and therefore have high crystallinity. Therefore, FeNi alloys tend to have high relative permeability but high magnetic loss. In contrast, when Si and Cr are introduced into an FeNi alloy, the crystalline structure of Fe and Ni is distorted. Therefore, it was predicted that the greater the amount of Si and Cr introduced, the greater the distortion of the crystalline structure of Fe and Ni, resulting in a significant decrease in relative permeability and magnetic loss. However, the present inventors' investigations have revealed that the introduction of Si can significantly reduce magnetic loss. Furthermore, while it has been conventionally believed that the introduction of Cr into an FeNi alloy adversely affects relative permeability, the present inventors' investigations have revealed that the melt viscosity can be reduced when the Cr content is within a specific range of 0.1% by mass to 6% by mass. Therefore, the (A) Fe-Ni-Si-Cr alloy magnetic powder containing Si and Cr in the amounts within the specific ranges exhibits high relative magnetic permeability due to the crystalline structure of Fe and Ni, and exhibits the specific effect of effectively reducing magnetic loss due to Si, while also achieving a low melt viscosity. Therefore, due to the specific effect of the (A) Fe-Ni-Si-Cr alloy magnetic powder, the cured product of the above-mentioned resin composition can maintain relative magnetic permeability and magnetic loss and achieve a low melt viscosity compared to conventional resin compositions containing magnetic powders.

[0015] However, the technical scope of the present invention is not limited by the above mechanism. In addition, although the above explanation of the mechanism has been given taking the case where Si and Cr are introduced into an FeNi alloy as an example, there is no limitation on the manufacturing method of (A) Fe-Ni-Si-Cr-based alloy magnetic powder, and therefore, those manufactured by methods other than introducing Si and Cr into an FeNi alloy are also included in the (A) Fe-Ni-Si-Cr-based alloy magnetic powder.

[0016] <(A)Fe-Ni-Si-Cr alloy magnetic powder> The resin composition contains, as component (A), (A) Fe-Ni-Si-Cr-based alloy magnetic powder. Thus, (A) Fe-Ni-Si-based alloy magnetic powder contains a combination of Fe, Ni, Si, and Cr.

[0017] The Cr content in the (A) Fe-Ni-Si-Cr alloy magnetic powder is 0.1% by mass or more, preferably 0.5% by mass or more, and more preferably 1% by mass or more, based on 100% by mass of the (A) Fe-Ni-Si-Cr alloy magnetic powder. The upper limit is 6% by mass or less, preferably 5.5% by mass or less, and more preferably 4% by mass or less. When the Cr content is within this range, the melt viscosity of the resin composition can be reduced, and a well-balanced increase in the relative magnetic permeability and decrease in magnetic loss of the cured resin composition can be achieved.

[0018] The Si content in the (A) Fe-Ni-Si-Cr alloy magnetic powder is preferably 0.1 mass% or more, preferably 0.15 mass% or more, more preferably 0.2 mass% or more, and preferably 5 mass% or less, more preferably 4 mass% or less, and even more preferably 3 mass% or less, relative to 100 mass% of the (A) Fe-Ni-Si-Cr alloy magnetic powder. When the Si content is within the above range, the melt viscosity of the resin composition can be reduced, and a good balance can be achieved between increasing the relative magnetic permeability and reducing magnetic loss in the cured product of the resin composition.

[0019] (A) The mass ratio (Si / Fe) of the amount of Si to the amount of Fe contained in the Fe-Ni-Si-Cr alloy magnetic powder is preferably 0.01 or more, more preferably 0.02 or more, and particularly preferably 0.04 or more, and is preferably 0.17 or less, more preferably 0.16 or less, and particularly preferably 0.14 or less. When the ratio (Si / Fe) of the amount of Si to the amount of Fe is within the above range, the relative permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0020] (A) The mass ratio (Si / Ni) of the amount of Si to the amount of Ni contained in the Fe-Ni-Si-Cr alloy magnetic powder is preferably 0.01 or more, more preferably 0.02 or more, and particularly preferably 0.04 or more, and is preferably 0.21 or less, more preferably 0.20 or less, and particularly preferably 0.18 or less. When the ratio (Si / Ni) of the amount of Si to the amount of Ni is within the above range, the relative permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0021] (A) The mass ratio (Cr / Fe) of the amount of Cr to the amount of Fe contained in the Fe-Ni-Si-Cr alloy magnetic powder is preferably 0.01 or more, more preferably 0.02 or more, and particularly preferably 0.04 or more, and is preferably 0.17 or less, more preferably 0.16 or less, and particularly preferably 0.14 or less. When the ratio (Cr / Fe) of the amount of Cr to the amount of Fe is within the above range, the melt viscosity of the resin composition can be reduced, and the relative permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0022] (A) The mass ratio (Cr / Ni) of the amount of Cr to the amount of Ni contained in the Fe-Ni-Si-Cr alloy magnetic powder is preferably 0.01 or more, more preferably 0.02 or more, and particularly preferably 0.04 or more, and is preferably 0.21 or less, more preferably 0.20 or less, and particularly preferably 0.18 or less. When the ratio (Cr / Ni) of the amount of Cr to the amount of Ni is within the above range, the melt viscosity of the resin composition can be reduced, and the relative permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0023] The amount of Fe contained in the (A) Fe-Ni-Si-Cr alloy magnetic powder is, relative to 100% by mass of the (A) Fe-Ni-Si-Cr alloy magnetic powder, preferably 33.00% by mass or more, more preferably 38.00% by mass or more, even more preferably 43.00% by mass or more, particularly preferably 48.00% by mass or more, and is preferably 65.00% by mass or less, more preferably 60.00% by mass or less, even more preferably 55.00% by mass or less, particularly preferably 52.00% by mass or less. When the amount of Fe is within the above range, the relative permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0024] The amount of Ni contained in the (A) Fe-Ni-Si-Cr alloy magnetic powder is, relative to 100% by mass of the (A) Fe-Ni-Si-Cr alloy magnetic powder, preferably 33.00% by mass or more, more preferably 38.00% by mass or more, even more preferably 40.00% by mass or more, particularly preferably 42.00% by mass or more, and is preferably 65.00% by mass or less, more preferably 60.00% by mass or less, even more preferably 54.00% by mass or less, particularly preferably 49.00% by mass or less. When the amount of Ni is within the above range, the relative permeability and magnetic loss of the cured resin composition can be effectively improved.

[0025] The total amount of Fe and Ni contained in the (A) Fe-Ni-Si-Cr alloy magnetic powder is, relative to 100% by mass of the (A) Fe-Ni-Si alloy magnetic powder, preferably 85% by mass or more, more preferably 87% by mass or more, and particularly preferably 92% by mass or more, and is preferably 99% by mass or less, more preferably 98.5% by mass or less, and particularly preferably 98% by mass or less. When the total amount of Fe and Ni is within the above range, the relative permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0026] (A) The mass ratio (Fe / Ni) of the amount of Fe to the amount of Ni contained in the Fe-Ni-Si-Cr alloy magnetic powder is preferably 0.5 or more, more preferably 0.7 or more, and particularly preferably 1.0 or more, and is preferably 1.21 or less, more preferably 1.20 or less, and particularly preferably 1.19 or less. When the ratio (Fe / Ni) of the amount of Fe to the amount of Ni is within the above range, the relative permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0027] The (A) Fe-Ni-Si-Cr alloy magnetic powder may contain any element other than Fe, Ni, and Si. Examples of such optional elements include elements derived from impurities that may be inevitably mixed in depending on the manufacturing method of the (A) Fe-Ni-Si-Cr alloy magnetic powder. Specific examples of such optional elements include P, S, Mn, Mo, Cu, and Co. However, from the perspective of significantly exhibiting the effects of the present invention, it is preferable that the (A) Fe-Ni-Si-Cr alloy magnetic powder does not contain any element other than Fe, Ni, Si, and Cr. Therefore, it is preferable that the (A) Fe-Ni-Si-Cr alloy magnetic powder contains only Fe, Ni, Si, and Cr.

[0028] (A) The amounts of Fe, Ni, Si, and Cr contained in the Fe-Ni-Si-Cr alloy magnetic powder can be measured using an inductively coupled plasma optical emission spectrometer (e.g., Agilent Technologies' ICP-OES 720ES).

[0029] The average particle size (D50) of the (A) Fe-Ni-Si-Cr alloy magnetic powder is preferably 1 μm or more, more preferably 2 μm or more, and particularly preferably 3 μm or more. When the average particle size (D50) of the (A) Fe-Ni-Si-Cr alloy magnetic powder is equal to or greater than the aforementioned lower limit, this is preferable in terms of safety in handling the (A) Fe-Ni-Si-Cr alloy magnetic powder. Furthermore, when the average particle size (D50) of the (A) Fe-Ni-Si-Cr alloy magnetic powder is equal to or greater than the aforementioned lower limit, the (A) Fe-Ni-Si-Cr alloy magnetic powder and the (B) thermosetting resin component can be mixed with high uniformity, effectively suppressing uneven distribution of the (A) Fe-Ni-Si-Cr alloy magnetic powder due to aggregation. This effectively improves the relative permeability and magnetic loss of the cured product. The upper limit of the average particle size (D50) of the (A) Fe-Ni-Si-Cr alloy magnetic powder is preferably 10 μm or less, more preferably 9 μm or less, and particularly preferably 7 μm or less. When the average particle size (D50) of the (A) Fe-Ni-Si-Cr alloy magnetic powder is equal to or less than the upper limit, the particles of the (A) Fe-Ni-Si-Cr alloy magnetic powder can be small. Therefore, the generation of large eddy current loss due to large particles can be suppressed, and magnetic loss can be effectively suppressed. This effect is particularly effective when the amount of the (A) Fe-Ni-Si-Cr alloy magnetic powder is large.

[0030] (A) The average particle size (D50) of Fe-Ni-Si-Cr alloy magnetic powder refers to the volume-based median diameter unless otherwise specified. This average particle size (D50) can be measured using a laser diffraction / scattering method based on Mie scattering theory. Specifically, a particle size distribution is created on a volume basis using a laser diffraction / scattering particle size distribution analyzer, and the median diameter is used as the average particle size (D50). The measurement sample is preferably a powder dispersed in water using ultrasonic waves. Examples of laser diffraction / scattering particle size distribution analyzers that can be used include the LA-500 manufactured by Horiba, Ltd. and the SALD-2200 manufactured by Shimadzu Corporation.

[0031] (A) The specific surface area of ​​the Fe-Ni-Si-Cr alloy magnetic powder is preferably 0.05 m 2 / g or more, more preferably 0.1m 2 / g or more, more preferably 0.5m 2 / g or more, preferably 20m 2 / g or less, more preferably 10m 2 / g or less, more preferably 5m 2 / g or less. (A) When the specific surface area of ​​the Fe-Ni-Si-Cr alloy magnetic powder is within the above range, the melt viscosity of the resin composition can be reduced, and the relative permeability and magnetic loss of the cured resin composition can be effectively improved. The specific surface area of ​​the magnetic 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.

[0032] The particles of the (A) Fe-Ni-Si-Cr based alloy magnetic powder are preferably spherical. According to the investigations of the present inventors, the particles of the (A) Fe-Ni-Si-Cr based alloy magnetic powder containing Si can usually have a shape with fewer irregularities on the surface compared to particles of FeNi alloy powder that does not contain Si or Cr, and therefore can have a shape that is closer to a sphere.

[0033] The aspect ratio (the value obtained by dividing the length of the major axis by the length of the minor axis) of the particles of the (A) Fe-Ni-Si-Cr alloy magnetic powder is preferably not more than 2, more preferably not more than 1.6, and even more preferably not more than 1.4. When the (A) Fe-Ni-Si-Cr alloy magnetic powder has an aspect ratio within the above range, magnetic loss can be suppressed and the melt viscosity of the resin composition can be reduced.

[0034] There are no limitations on the manufacturing method of the (A) Fe-Ni-Si-Cr-based alloy magnetic powder. The (A) Fe-Ni-Si-Cr-based alloy magnetic powder can be manufactured, for example, by atomization. This atomization method typically involves rapidly solidifying a bath of molten iron, nickel, Si, and Cr by spraying high-pressure water or gas onto the falling bath of molten iron, nickel, Si, and Cr. Among the atomization methods described above, water atomization, in which water is sprayed onto the falling bath of molten iron, nickel, Si, and Cr, is preferred. For example, the method described in JP 2018-178254 A can be used as this atomization method.

[0035] The content (volume %) of the (A) Fe-Ni-Si-Cr alloy magnetic powder is preferably 30% by volume or more, more preferably 40% by volume or more, and particularly preferably 50% by volume or more, relative to 100% by volume of the nonvolatile components contained in the resin composition. It is also preferably 90% by volume or less, more preferably 80% by volume or less, and particularly preferably 70% by volume or less. When the amount of the (A) Fe-Ni-Si-Cr alloy magnetic powder is within the above range, the relative permeability and magnetic loss of the cured resin composition can be effectively improved. Furthermore, when the amount of the (A) Fe-Ni-Si-Cr alloy magnetic powder is below the upper limit of the above range, the melt viscosity of the resin composition can be effectively reduced, making it easy to form a paste.

[0036] 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 can be 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.

[0037] The content (mass %) of the (A) Fe-Ni-Si-Cr alloy magnetic powder is preferably 40 mass % or more, more preferably 50 mass % or more, and particularly preferably 55 mass % or more, relative to 100 mass % of the nonvolatile components contained in the resin composition. It is also preferably 95 mass % or less, more preferably 90 mass % or less, and particularly preferably 85 mass % or less. When the amount of the (A) Fe-Ni-Si-Cr alloy magnetic powder is within the above range, the relative permeability and magnetic loss of the cured resin composition can be effectively improved. Furthermore, when the amount of the (A) Fe-Ni-Si-Cr alloy magnetic powder is below the upper limit of the above range, the melt viscosity of the resin composition can be effectively reduced, making it easy to form a paste.

[0038] The total amount of magnetic powder contained in a resin composition is usually expressed as the total amount of (A) Fe-Ni-Si-Cr-based alloy magnetic powder and (C) optional magnetic powder, described below. The total amount (vol %) of magnetic powder contained in this resin composition is preferably 50 vol % or more, more preferably 60 vol % or more, even more preferably 65 vol % or more, particularly preferably 70 vol % or more, based on 100 vol % of nonvolatile components in the resin composition, and is preferably 90 vol % or less, more preferably 86 vol % or less, and particularly preferably 82 vol % or less. When the total amount of magnetic powder is within the above range, the relative permeability and magnetic loss of the cured resin composition can be effectively improved. Furthermore, when the total amount of magnetic powder is below the upper limit of the above range, the melt viscosity of the resin composition can usually be effectively reduced, making it easy to form a paste.

[0039] The total amount of magnetic powder contained in a resin composition is usually expressed as the total amount of (A) Fe-Ni-Si-Cr-based alloy magnetic powder and (C) optional magnetic powder, described below. The total amount (mass %) of magnetic powder contained in this resin composition is preferably 70 mass % or more, more preferably 80 mass % or more, even more preferably 85 mass % or more, particularly preferably 90 mass % or more, and preferably 99 mass % or less, more preferably 98 mass % or less, and particularly preferably 97 mass % or less, based on 100 mass % of the nonvolatile components in the resin composition. When the total amount of magnetic powder is within the above range, the relative permeability and magnetic loss of the cured resin composition can be effectively improved. Furthermore, when the total amount of magnetic powder is below the upper limit of the above range, the melt viscosity of the resin composition can usually be effectively reduced, making it easy to form a paste.

[0040] <(B) Thermosetting resin> The resin composition contains a thermosetting resin (B) as component (B). The thermosetting resin (B) can typically bind magnetic powder such as an Fe-Ni-Si-Cr-based alloy magnetic powder (A). Furthermore, the thermosetting resin (B) typically reacts with heat to form bonds and harden. Therefore, a cured product can be obtained by curing a resin composition containing a combination of an Fe-Ni-Si-Cr-based alloy magnetic powder (A) and a thermosetting resin (B). This cured product has excellent relative magnetic permeability and magnetic loss, allowing for the formation of an excellent magnetic layer.

[0041] 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.

[0042] The (B) thermosetting resin preferably contains (B-1) epoxy resin. (B-1) Epoxy resin refers to a resin having one or more epoxy groups in its molecule. When the (B) thermosetting resin contains (B-1) epoxy resin, the dispersibility of the (A) Fe-Ni-Si-Cr alloy magnetic powder can be improved, and the relative magnetic permeability and magnetic loss of the cured resin composition can be effectively improved.

[0043] 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 include heterocyclic epoxy resins, spiro ring-containing epoxy resins, cyclohexane epoxy resins, cyclohexanedimethanol epoxy resins, trimethylol epoxy resins, tetraphenylethane epoxy resins, epoxy resins containing a condensed ring skeleton such as naphthylene ether epoxy resins, tert-butyl-catechol epoxy resins, naphthalene epoxy resins, naphthol epoxy resins, anthracene epoxy resins, and naphthol novolac epoxy resins, isocyanurate epoxy resins, epoxy resins containing an alkyleneoxy skeleton and a butadiene skeleton, and epoxy resins containing a fluorene structure. The (B-1) epoxy resin may be used alone or in combination of two or more.

[0044] The (B-1) epoxy resin 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 (B-1) epoxy resin (100% by mass) is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

[0045] The (B-1) epoxy resin preferably has an aromatic structure. When two or more epoxy resins are used, it is preferable that at least one of the epoxy resins has an aromatic structure. The aromatic structure is a chemical structure generally defined as aromatic, and includes polycyclic aromatic rings and aromatic heterocycles.

[0046] (B-1) epoxy resins include epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). (B-1) epoxy resin may be liquid epoxy resin alone, solid epoxy resin alone, or a combination of liquid epoxy resin and solid epoxy resin. Of these, (B-1) epoxy resin preferably contains liquid epoxy resin, and particularly preferably contains liquid epoxy resin alone.

[0047] The liquid epoxy resin is preferably a liquid epoxy resin having two or more epoxy groups per molecule. Examples of the liquid epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AF epoxy resin, naphthalene epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, phenol novolac epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane epoxy resin, cyclohexanedimethanol 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 epoxy resin. Among these, bisphenol A epoxy resin and bisphenol F epoxy resin are particularly preferred.

[0048] 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; "jER807" and "1750" (bisphenol F-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "jER152" (phenol novolac-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", and "604" (glycidylamine-type epoxy resins) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycirol-type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L" and "EP-3980S" (glycidylamine-type epoxy resins) manufactured by ADEKA Corporation; and "EP-4088S" (glycidylamine-type epoxy resins) manufactured by ADEKA Corporation. peropentadiene-type epoxy resins); "ZX-1059" manufactured by Nippon Steel Chemical & Material Co., Ltd. (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin); "EX-721" manufactured by Nagase ChemteX Corporation (glycidyl ester-type epoxy resin); "EX-991L" manufactured by Nagase ChemteX Corporation (an epoxy resin containing an alkyleneoxy skeleton); "Celloxide 2021P" and "Celloxide 2081" manufactured by Daicel Corporation (alicyclic epoxy resins with an ester skeleton); "PB-3600" manufactured by Daicel Corporation, "JP-100" and "JP-200" manufactured by Nippon Soda Co., Ltd. (epoxy resins with a butadiene structure); "ZX-1658" and "ZX-1658GS" manufactured by Nippon Steel Chemical & Material Co., Ltd. (liquid 1,4-glycidylcyclohexane-type epoxy resin); and "EG-280" manufactured by Osaka Gas Chemicals Co., Ltd. (an epoxy resin containing a fluorene structure). The liquid epoxy resin may be used alone or in combination of two or more.

[0049] The solid epoxy resin is preferably a solid epoxy resin having three or more epoxy groups in one molecule, more preferably an aromatic solid epoxy resin having three or more epoxy groups in one molecule.The solid epoxy resin is preferably a bixylenol type epoxy resin, a naphthalene type epoxy resin, a naphthalene type tetrafunctional epoxy resin, a cresol novolac type epoxy resin, a dicyclopentadiene type epoxy resin, a trisphenol type epoxy resin, a naphthol type epoxy resin, a biphenyl type epoxy resin, a naphthylene ether type epoxy resin, an anthracene type epoxy resin, a bisphenol A type epoxy resin, a bisphenol AF type epoxy resin, or a tetraphenylethane type epoxy resin, and particularly preferably a dicyclopentadiene type epoxy resin.

[0050] Specific examples of solid epoxy resins include DIC Corporation's "HP4032H" (naphthalene-type epoxy resin); DIC Corporation's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC Corporation's "N-690" (cresol novolac-type epoxy resin); DIC Corporation's "N-695" (cresol novolac-type epoxy resin); and DIC Corporation's "HP-7200," "HP-7200HH," and "HP-7200H" (dicyclopentadiene-type epoxy resins). DIC's "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", and "HP6000" (naphthylene ether type epoxy resins); Nippon Kayaku's "EPPN-502H" (trisphenol type epoxy resin); Nippon Kayaku's "NC7000L" (naphthol novolac type epoxy resin); Nippon Kayaku's "NC3000H", "NC3000", "NC3000L", and "NC3100" (biphenyl type epoxy resins). 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.; "YX4000H", "YX4000", and "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX4000HK" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; Examples of suitable solid epoxy resins include "YX7700" (xylene structure-containing novolac epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YL7760" (bisphenol AF epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (solid bisphenol A epoxy resin) manufactured by Mitsubishi Chemical Corporation; and "jER1031S" (tetraphenylethane epoxy resin) manufactured by Mitsubishi Chemical Corporation. One type of solid epoxy resin may be used alone, or two or more types may be used in combination.

[0051] 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 particularly preferably 10 or more.

[0052] The epoxy equivalent of the (B-1) epoxy resin is preferably 50 g / eq to 5000 g / eq, more preferably 50 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 according to JIS K7236.

[0053] 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.

[0054] The amount (mass %) of the (B-1) epoxy resin contained in the resin composition is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, and particularly preferably 1 mass % or more, relative to 100 mass % of the nonvolatile components of the resin composition, and is preferably 10 mass % or less, more preferably 5 mass % or less, and particularly preferably 3 mass % or less. When the amount of the (B-1) epoxy resin is within this range, the melt viscosity of the resin composition can be reduced, and the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0055] The amount (mass %) of the (B-1) epoxy resin contained in the resin composition is preferably 20 mass % or more, more preferably 30 mass % or more, and particularly preferably 40 mass % or more, relative to 100 mass % of the resin components of the resin composition, and is preferably 90 mass % or less, more preferably 80 mass % or less, and particularly preferably 70 mass % or less. When the amount of the (B-1) epoxy resin is within the above range, the melt viscosity of the resin composition can be reduced, and the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0056] When the (B) thermosetting resin contains a (B-1) epoxy resin, the (B) thermosetting resin may contain a resin capable of reacting with and bonding to the (B-1) epoxy resin. Hereinafter, the resin capable of reacting with and bonding to the (B-1) epoxy resin 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. The (B-2) curing agent may be used alone or in combination of two or more. Among these, phenolic resins are preferred.

[0057] 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.

[0058] 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.

[0059] The active ester resin may be a compound having one or more, preferably two or more, active ester groups per molecule. Among these, preferred active 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 active 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, active ester resins obtained from a carboxylic acid compound and a hydroxy compound are preferred, and active 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, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.

[0060] 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.

[0061] 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. Examples of active ester resins containing acetylated compounds include "DC808" (manufactured by Mitsubishi Chemical Corporation); active ester resins containing benzoylated phenol novolac include "YLH1026" (manufactured by Mitsubishi Chemical Corporation); active ester resins that are acetylated phenol novolac include "DC808" (manufactured by Mitsubishi Chemical Corporation); and 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).

[0062] 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) Examples of suitable amine resins include 4,4'-bis(4-aminophenyl)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, and bis(4-(3-aminophenoxy)phenyl)sulfone. Commercially available amine resins may be used, such as "KAYABOND C-200S," "KAYABOND C-100," "KAYAHARD AA," "KAYAHARD AB," and "KAYAHARD AS" manufactured by Nippon Kayaku Co., Ltd., and "Epicure W" manufactured by Mitsubishi Chemical Corporation.

[0063] 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(methylenediphenylenecarbodiimide), 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.

[0064] 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. Examples of suitable anhydrides include anhydrides, 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), and polymeric anhydrides such as styrene-maleic acid resins, which are copolymers of styrene and maleic acid. Commercially available acid anhydride resins include, for example, "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.

[0065] Specific examples of benzoxazine resins include "JBZ-OD100," "JBZ-OP100D," and "ODA-BOZ" manufactured by JFE Chemical Corporation; "Pd" and "Fa" manufactured by Shikoku Chemical Industry Co., Ltd.; and "HFB2006M" manufactured by Showa Polymer Co., Ltd.

[0066] 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 a trimer), all of which are manufactured by Lonza Japan.

[0067] Examples of thiol-based resins include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), and tris(3-mercaptopropyl)isocyanurate.

[0068] 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 particularly 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.

[0069] 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, particularly preferably 0.5 or more, and preferably 10 or less, more preferably 5 or less, particularly preferably 3 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 total value for all epoxy resins obtained by dividing the mass of the nonvolatile components of each epoxy resin by the epoxy equivalent. The number of active groups in the (B-2) curing agent is the total value for all curing agents obtained by dividing the mass of the nonvolatile components of each curing agent by the active group equivalent.

[0070] The amount (mass %) of the (B-2) curing agent contained in the resin composition is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, and particularly preferably 1 mass % or more, relative to 100 mass % of the nonvolatile components of the resin composition, and is preferably 10 mass % or less, more preferably 5 mass % or less, and particularly preferably 3 mass % or less. When the amount of the (B-2) curing agent is within the above range, the melt viscosity of the resin composition can be reduced, and the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0071] The amount (mass %) of the (B-2) curing agent contained in the resin composition is preferably 10 mass % or more, more preferably 20 mass % or more, and particularly preferably 30 mass % or more, relative to 100 mass % of the resin components of the resin composition, and is preferably 50 mass % or less, more preferably 45 mass % or less, and particularly preferably 40 mass % or less. When the amount of the (B-2) curing agent is within the above range, the melt viscosity of the resin composition can be reduced, and the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0072] The range of the weight average molecular weight (Mw) of the (B) thermosetting resin can usually be the same as the range of the weight average molecular weight of the (B-1) epoxy resin described above.

[0073] The amount (% by mass) of the (B) thermosetting resin contained in the resin composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more, relative to 100% by mass of the nonvolatile components of the resin composition, and is preferably 30% by mass or less, more preferably 20% by mass or less, and particularly preferably 10% by mass or less. When the amount of the (B) thermosetting resin is within the above range, the melt viscosity of the resin composition can be reduced, and the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0074] The amount (mass %) of the (B) thermosetting resin contained in the resin composition is preferably 30 mass % or more, more preferably 50 mass % or more, and particularly preferably 60 mass % or more, relative to 100 mass % of the resin components of the resin composition, and is preferably 99 mass % or less, more preferably 90 mass % or less, and particularly preferably 85 mass % or less. When the amount of the (B) thermosetting resin is within the above range, the melt viscosity of the resin composition can be reduced, and the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0075] The total amount (mass %) of the (A) Fe-Ni-Si-Cr alloy magnetic powder and (B) thermosetting resin is preferably 50 mass % or more, more preferably 55 mass % or more, and particularly preferably 60 mass % or more, relative to 100 mass % of the nonvolatile components of the resin composition, and is preferably 100 mass % or less, more preferably 95 mass % or less, and particularly preferably 90 mass % or less, or 85 mass % or less. When the amount of the (B) thermosetting resin is within this range, the melt viscosity of the resin composition can be reduced, and the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0076] <(C) Any magnetic powder (magnetic powder other than Fe-Ni-Si-Cr alloy magnetic powder)> The resin composition may further contain, as an optional component, (C) a magnetic powder other than the Fe-Ni-Si-Cr-based alloy magnetic powder in addition to the above-mentioned components (A) and (B). This "(C) magnetic powder other than the Fe-Ni-Si-Cr-based alloy magnetic powder" as component (C) may be referred to as "(C) optional magnetic powder" as appropriate.

[0077] As the (C) optional magnetic powder, particles of a material having a relative magnetic permeability greater than 1 can be used. The material of the (C) optional magnetic powder is usually an inorganic material, and may be a soft magnetic material or a hard magnetic material. Furthermore, the material of the (C) optional magnetic powder may be used alone or in combination of two or more types. Therefore, the (C) optional 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. Furthermore, the (C) optional magnetic powder may be used alone or in combination of two or more types. In particular, it is preferable that the (C) optional magnetic powder contains a soft magnetic powder, and it is more preferable that it contains only a soft magnetic powder.

[0078] (C) Examples of the optional magnetic powder include magnetic metal oxide powder and magnetic metal powder.

[0079] Examples of magnetic metal oxide powders include ferrite-based magnetic powders and iron oxide powders such as iron oxide powder (III) and triiron tetroxide powder. Among these, ferrite-based magnetic powders are preferred. Therefore, it is preferable that (C) optional magnetic powder contains ferrite-based magnetic powder. In one example, only ferrite-based magnetic powder may be used as (C) optional magnetic powder. Ferrite-based magnetic powders are usually made of composite oxides whose main component is iron oxide and are chemically stable. Therefore, ferrite-based magnetic powders offer advantages such as high corrosion resistance, low risk of fire, and resistance to demagnetization.

[0080] Examples of ferrite-based magnetic powders include Fe-Mn ferrite powder, Fe-Mn-Zn 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, Fe-Ni-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.

[0081] Among ferrite-based magnetic powders, ferrite-based magnetic powders containing at least one element selected from the group consisting of Mn, Zn, Ni, and Cu are preferred. Therefore, (C) the optional magnetic powder preferably includes a ferrite-based magnetic powder containing at least one element selected from the group consisting of Mn, Zn, Ni, and Cu. In one example, only ferrite-based magnetic powders containing at least one element selected from the group consisting of Mn, Zn, Ni, and Cu may be used as (C) the optional magnetic powder. Examples of such preferred ferrite-based magnetic powders include Fe-Mn ferrite powder, Fe-Mn-Zn ferrite powder, Fe-Mn-Mg ferrite powder, Fe-Mn-Mg-Sr ferrite powder, Fe-Mg-Zn ferrite powder, Fe-Zn-Mn ferrite powder, Fe-Cu-Zn ferrite powder, Fe-Ni-Zn ferrite powder, Fe-Ni-Zn-Cu ferrite powder, Fe-Ba-Zn ferrite powder, Fe-Ba-Ni ferrite powder, and Fe-Ba-Ni-Co ferrite powder. Among these, ferrite-based magnetic powders containing at least one element selected from the group consisting of Zn and Mn are more preferred, and ferrite-based magnetic powders containing Zn and Mn are particularly preferred. Therefore, as the ferrite-based magnetic powder, Fe-Mn-Zn ferrite powder and Fe-Mn ferrite powder are preferred, with Fe-Mn-Zn ferrite powder being particularly preferred. The Fe-Zn-Mn ferrite powder refers to ferrite powder containing Fe, Zn, and Mn, and the Fe-Mn ferrite powder refers to ferrite powder containing Fe and Mn.

[0082] Examples of magnetic metal powders include pure iron powder; crystalline or amorphous alloy magnetic powders such as Fe-Mn-Zn alloy powder, Fe-Si alloy powder, Fe-Mn 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-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. Among these, alloy magnetic powders other than Fe-Ni-Si-Cr alloy magnetic powders are preferred. Therefore, it is preferable that (C) optional magnetic powder contains an alloy magnetic powder other than Fe-Ni-Si-Cr alloy magnetic powder. In one example, the (C) arbitrary magnetic powder may be an alloy magnetic powder other than an Fe-Ni-Si-Cr alloy magnetic powder. Furthermore, among the alloy magnetic powders, an iron alloy powder is more preferable.

[0083] Particularly preferred magnetic metal powders are iron alloy magnetic powders containing Fe and at least one element selected from the group consisting of Si and Cr, with Fe-Cr-Si alloy powders being particularly preferred. Fe-Cr-Si alloy powders refer to alloy powders containing Fe, Cr, and Si.

[0084] (C) As the optional magnetic powder, commercially available magnetic powders may be used. Specific examples of commercially available magnetic powders include "MZ03S", "M03S", "M05S", "M001", and "MZ05S" manufactured by Powdertech Co., Ltd.; "PST-S" manufactured by Sanyo Special Steel Co., Ltd.; "AW2-08", "AW2-08PF20F", "AW2-08PF10F", "AW2-08PF3F", "Fe-3.5Si-4.5CrPF20F", "Fe-50NiPF20F", and "Fe-80Ni-4MoPF20F" manufactured by Epson Atmix Corporation; and "CVD iron powder 0.7 μm", "LD-M", "LD-MH", "KNI-106", "KNI-106GSM", and "K" manufactured by JFE Chemical Corporation. Examples of suitable magnetic powders include "NI-106GS," "KNI-109," "KNI-109GSM," and "KNI-109GS" manufactured by Toda Kogyo Co., Ltd.; "KNS-415," "BSF-547," "BSF-029," "BSN-125," "BSN-125," "BSN-714," "BSN-828," "S-1281," "S-1641," "S-1651," "S-1470," "S-1511," and "S-2430" manufactured by Toda Kogyo Co., Ltd.; "JR09P2" manufactured by Japan Metals and Chemical Industries, Ltd.; "Nanotek" manufactured by CIK Nanotech; "JEMK-S" and "JEMK-H" manufactured by Kinseimatec Co., Ltd.; "Yttrium iron oxide" manufactured by Aldrich; and "MA-RCO-5" manufactured by Dowa Electronics Co., Ltd. (C). The optional magnetic powders may be used singly or in combination of two or more.

[0085] The (C) optional magnetic powder preferably has a smaller average particle size than the (A) Fe-Ni-Si-Cr alloy magnetic powder. When the (C) optional magnetic powder has a smaller average particle size than the (A) Fe-Ni-Si-Cr alloy magnetic powder, the (C) optional magnetic powder can enter the gaps between the particles of the (A) Fe-Ni-Si-Cr alloy magnetic powder, allowing for high loading of the magnetic powder and thereby improving magnetic properties such as relative permeability.

[0086] The ratio of the average particle size of the (C) arbitrary magnetic powder to the average particle size of the (A) Fe-Ni-Si-Cr alloy magnetic powder (average particle size of the (C) arbitrary magnetic powder / average particle size of the (A) Fe-Ni-Si-Cr alloy magnetic powder) is preferably within a specific range. Specifically, the ratio (average particle size of the (C) arbitrary magnetic powder / average particle size of the (A) Fe-Ni-Si-Cr alloy magnetic powder) is preferably 0.001 or more, more preferably 0.01 or more, particularly preferably 0.05 or more, and is preferably 0.9 or less, more preferably 0.6 or less, particularly preferably 0.3 or less. When the ratio (average particle size of the (C) arbitrary magnetic powder / average particle size of the (A) Fe-Ni-Si-Cr alloy magnetic powder) is within the above range, the relative magnetic permeability and magnetic loss of the cured resin composition can be effectively improved.

[0087] The specific range of the average particle size of the (C) optional magnetic powder is preferably 0.05 μm or more, more preferably 0.1 μm or more, particularly preferably 0.2 μm or more, and preferably 3 μm or less, more preferably 2 μm or less, particularly preferably 1.5 μm or less. When the average particle size of the (C) optional magnetic powder is equal to or greater than the lower limit, the viscosity of the resin composition can be reduced. On the other hand, when the average particle size is equal to or less than the upper limit, the relative permeability and magnetic loss of the cured resin composition can be effectively improved.

[0088] (C) The average particle size of any magnetic powder can be measured by the same method as that for (A) the average particle size of the Fe-Ni-Si-Cr alloy magnetic powder.

[0089] The specific surface area of ​​the (C) arbitrary magnetic powder is preferably larger than the specific surface area of ​​the (A) Fe-Ni-Si-Cr alloy magnetic powder. The specific range of the specific surface area of ​​the (C) arbitrary magnetic powder is preferably 0.1 m 2 / g or more, more preferably 1.0m 2 / g or more, particularly preferably 2m 2 / g or more, preferably 40m 2 / g or less, more preferably 30m 2 / g or less, particularly preferably 20m 2 / g or less.

[0090] (C) The particles of any magnetic powder are preferably spherical or ellipsoidal. The aspect ratio (ratio of the major axis length divided by the minor axis length) of any magnetic powder particle (C) 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 easier to improve the relative magnetic permeability. On the other hand, when the shape of the magnetic powder particles is closer to spherical, it is easier to reduce magnetic loss.

[0091] (C) The true specific gravity of any magnetic powder is, for example, 4 g / cm 3 ~10g / cm 3 It is possible.

[0092] The amount (vol %) of the optional magnetic powder (C) contained in the resin composition may be 0% or more than 0% by volume, relative to 100% by volume of the nonvolatile components of the resin composition, and is preferably 1% by volume or more, more preferably 5% by volume or more, particularly preferably 10% by volume or more, and is preferably 40% by volume or less, more preferably 35% by volume or less, particularly preferably 30% by volume or less. When the amount (vol %) of the optional magnetic powder (C) is within the above range, the relative permeability and magnetic loss of the cured resin composition can be effectively improved.

[0093] The amount (mass%) of the optional magnetic powder (C) contained in the resin composition may be 0 mass% or more, and is preferably 1 mass% or more, more preferably 5 mass% or more, and particularly preferably 10 mass% or more, and is preferably 40 mass% or less, more preferably 35 mass% or less, and particularly preferably 30 mass% or less, relative to 100 mass% of the nonvolatile components of the resin composition. When the amount (mass%) of the optional magnetic powder (C) is within the above range, the relative magnetic permeability and magnetic loss of the cured resin composition can be effectively improved.

[0094] When (A) Fe-Ni-Si-Cr-based alloy magnetic powder and (C) optional magnetic powder are used in combination, the volume ratio of (C) optional magnetic powder to (A) Fe-Ni-Si-Cr-based alloy magnetic powder ((C) component / (A) component) is preferably within a specific range. Specifically, the volume ratio ((C) component / (A) component) is preferably 0.01 or more, more preferably 0.1 or more, even more preferably 0.2 or more, and particularly preferably 0.3 or more, and is preferably 0.9 or less, more preferably 0.8 or less, and particularly preferably 0.7 or less. When the volume ratio ((C) component / (A) component) is within the above range, the relative magnetic permeability and magnetic loss of the cured resin composition can be effectively improved.

[0095] When (A) Fe-Ni-Si-Cr-based alloy magnetic powder and (C) any magnetic powder are used in combination, the mass ratio of (C) any magnetic powder to (A) Fe-Ni-Si-Cr-based alloy magnetic powder ((C) component / (A) component) is preferably within a specific range. Specifically, the mass ratio ((C) component / (A) component) is preferably 0.1 or more, more preferably 0.15 or more, and particularly preferably 0.2 or more, and is preferably 1 or less, more preferably 0.8 or less, and particularly preferably 0.7 or less. When the mass ratio ((C) component / (A) component) is within the above range, the relative magnetic permeability and magnetic loss of the cured resin composition can be effectively improved.

[0096] <(D) Thermoplastic resin> The resin composition may further contain a thermoplastic resin (D) as an optional component in combination with the above-described components (A) to (C). The thermoplastic resin (D) as component (D) does not include those corresponding to the above-described components (A) to (C). The thermoplastic resin (D) can effectively improve the mechanical properties of a cured product of the resin composition.

[0097] Examples of the (D) thermoplastic resin 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 (D) thermoplastic resin may be used alone or in combination of two or more.

[0098] Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A, bisphenol F, bisphenol S, bisphenolacetophenone, novolac, biphenyl, fluorene, dicyclopentadiene, norbornene, naphthalene, anthracene, adamantane, terpene, and trimethylcyclohexane. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group. Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (both of which are 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 Chemical & Material Co., Ltd.; "YL7500BH30," "YX6954BH30," "YX7553," "YX7553BH30," "YL7769BH30," "YL6794," "YL7213," "YL7290," "YL7482," and "YL7891BH30" manufactured by Mitsubishi Chemical Corporation; and the like.

[0099] 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 (polyimides described in JP-A No. 2006-37083), and polysiloxane skeleton-containing polyimides (polyimides described in JP-A Nos. 2002-12667 and 2000-319386).

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] A specific example of the polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

[0105] Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

[0106] A specific example of the polyphenylene ether resin is NORYL SA90 manufactured by SABIC, etc. A specific example of the polyetherimide resin is ULTEM manufactured by GE, etc.

[0107] Examples of polycarbonate resins include hydroxyl group-containing carbonate resins, phenolic hydroxyl group-containing carbonate resins, carboxyl group-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane group-containing carbonate resins. 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. Specific examples of polyether ether ketone resins include "Sumiploy K" manufactured by Sumitomo Chemical Co., Ltd.

[0108] 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.

[0109] The weight average molecular weight (Mw) of the (D) thermoplastic resin is preferably greater than 5,000, more preferably at least 8,000, even more preferably at least 10,000, and particularly 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.

[0110] The amount (mass%) of the (D) thermoplastic resin contained in the resin composition may be 0 mass% or more, and is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, particularly preferably 0.1 mass% or more, and is preferably 5 mass% or less, more preferably 3 mass% or less, particularly preferably 2 mass% or less, relative to 100 mass% of the nonvolatile components of the resin composition. When the amount of the (D) thermoplastic resin is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0111] The amount (mass%) of the (D) thermoplastic resin contained in the resin composition may be 0 mass% or more, and is preferably 1 mass% or more, more preferably 2 mass% or more, particularly preferably 3 mass% or more, and is preferably 15 mass% or less, more preferably 10 mass% or less, particularly preferably 5 mass% or less, relative to 100 mass% of the resin components of the resin composition. When the amount of the (D) thermoplastic resin is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0112] <(E) Dispersant> The resin composition according to one embodiment of the present invention may further contain an optional dispersant (E) in combination with the above-described components (A) to (D). The dispersant (E) as component (E) does not include any of the above-described components (A) to (D). The dispersant (E) can improve the dispersibility of magnetic powders such as the Fe-Ni-Si-Cr alloy magnetic powder (A) and the optional magnetic powder (C).

[0113] There are no limitations on the type of (E) dispersant. For example, the (E) dispersant may contain a functional group capable of adsorbing to magnetic powder, and when adsorbed to the magnetic powder, disperse the magnetic powder due to repulsion between (E) dispersants (e.g., electrostatic repulsion, steric repulsion, etc.). Examples of such (E) dispersants include acidic dispersants and basic dispersants.

[0114] Acidic dispersants typically contain acidic functional groups such as carboxyl groups, sulfo groups (-SO3H), sulfate groups (-OSO3H), phosphono groups (-PO(OH)2), phosphonooxy groups (-OPO(OH)2), hydroxyphosphoryl groups (-PO(OH)-), and sulfanyl groups (-SH). The acidic functional groups typically have a dissociable proton and may be neutralized with a base such as an amine or hydroxide ion. Preferred acidic dispersants include, for example, acidic polymer dispersants containing a polymer chain such as a polyoxyalkylene chain or a polyether chain. Preferred examples of acidic dispersants include "C-2093I" and "SC-1015F (a multifunctional comb-type functional polymer having an ionic group in the main chain and a polyoxyalkylene chain in the graft chain)" manufactured by NOF Corporation; "ED152," "ED153," "ED154," "ED118," "ED174," "ED251," and "DA-375" (polyether-type phosphate ester dispersants) manufactured by Kusumoto Chemicals Co., Ltd.; "RS-410," "RS-610," and "RS-710" (pH 1.9) (phosphate ester dispersants) from the "Phosphanol" series manufactured by Toho Chemical Industry Co., Ltd.; and "AKM-0531," "AFB-1521," "SC-0505K," and "SC-0708A" from the "Marialim" series manufactured by NOF Corporation.

[0115] Basic dispersants typically contain basic functional groups such as primary, secondary, and tertiary amino groups; ammonium groups; imino groups; and nitrogen-containing heterocyclic groups such as pyridine, pyrimidine, pyrazine, imidazole, and triazole. The basic functional groups may be neutralized with an acid such as an organic acid or an inorganic acid. Preferred basic dispersants include basic polymer dispersants containing polymer chains such as polyester chains. Preferred examples of basic dispersants include "PB-881" (polyamine-based dispersant containing polyester chains) manufactured by Ajinomoto Fine-Techno Co., Inc.

[0116] The (E) dispersant may be used alone or in combination of two or more.

[0117] The amount (mass %) of the (E) dispersant contained in the resin composition may be 0 mass % or more, and is preferably 0.01 mass % or more, more preferably 0.1 mass % or more, particularly preferably 0.2 mass % or more, and is preferably 5 mass % or less, more preferably 3 mass % or less, particularly preferably 2 mass % or less, relative to 100 mass % of the nonvolatile components of the resin composition. When the amount of the (E) dispersant is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0118] The amount (mass %) of the (E) dispersant contained in the resin composition may be 0 mass % or more, and is preferably 1 mass % or more, more preferably 3 mass % or more, particularly preferably 5 mass % or more, and is preferably 30 mass % or less, more preferably 25 mass % or less, particularly preferably 20 mass % or less, relative to 100 mass % of the resin components of the resin composition. When the amount of the (E) dispersant is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0119] <(F) Curing accelerator> The resin composition may further contain a (F) curing accelerator as an optional component in combination with the above-described components (A) to (E). The (F) curing accelerator as component (F) does not include those corresponding to the above-described components (A) to (E). The (F) curing accelerator functions as a catalyst for the reaction of the (B) thermosetting resin, and can therefore accelerate the curing of the resin composition.

[0120] Examples of the (F) curing accelerator include phosphorus-based curing accelerators, imidazole-based curing accelerators, amine-based curing accelerators, guanidine-based curing accelerators, metal-based curing accelerators, and urea-based curing accelerators. One (F) curing accelerator may be used alone, or two or more (F) curing accelerators may be used in combination. Among these, phosphorus-based curing accelerators and imidazole-based curing accelerators are preferred, and phosphorus-based curing accelerators are more preferred.

[0121] Examples of the phosphorus-based curing accelerator include phosphonium salts and phosphines. Examples of the phosphonium salt include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, n-butylphosphonium tetraphenylborate, bis(tetrabutylphosphonium)pyromellitate, tetrabutylphosphonium hydrogenhexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butylmethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, and propyltriphenylphosphonium. bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and aromatic phosphonium salts such as butyltriphenylphosphonium thiocyanate.

[0122] Examples of phosphines include aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine; dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, and tris(2,5-dimethylphenyl)phosphine. tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2- Examples include aromatic phosphines such as bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; and aromatic phosphine-quinone adducts such as triphenylphosphine-p-benzoquinone adduct.

[0123] As the phosphorus-based curing accelerator, commercially available products may be used, for example, "TBP-DA" manufactured by Hokko Chemical Industry Co., Ltd.

[0124] 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, 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-undecylimidazole, 1-cyanoethyl-2-phenylimidazolium 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, 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, and 2-ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole are preferred. As the imidazole-based curing accelerator, commercially available products may be used, such as "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", "2PHZ-PW", "1B2PZ", and "1B2PZ-10M" manufactured by Shikoku Chemicals Corporation.

[0125] 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. Commercially available amine curing accelerators may also be used, such as "PN-50," "PN-23," and "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc.

[0126] Examples of guanidine-based 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.

[0127] 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.

[0128] Examples of the urea-based curing accelerator include 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, and 3-(3,4-dimethylphenyl)-1,1-dimethylurea. aromatic dimethylureas such as toluene bis(dimethylurea), 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N',N'-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N',N'-dimethylurea) [toluene bisdimethylurea].

[0129] The amount (mass%) of the (F) 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 0.005 mass% or more, and particularly preferably 0.01 mass% or more, and is preferably 3 mass% or less, more preferably 2 mass% or less, and particularly preferably 1 mass% or less, relative to 100 mass% of the non-volatile components of the resin composition.

[0130] The amount (mass%) of the (F) curing accelerator contained in the resin composition may be 0 mass% or more than 0 mass%, and is preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and particularly preferably 0.5 mass% or more, and is preferably 5 mass% or less, more preferably 3 mass% or less, and particularly preferably 2 mass% or less, relative to 100 mass% of the resin components of the resin composition.

[0131] The total content of the (B), (E), and (F) components is preferably 1% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2% by mass or more, relative to 100% by mass of the non-volatile components of the resin composition; and is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 5% by mass or less.

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

[0133] (G) Examples of optional additives include radical polymerizable compounds such as maleimide-based radical polymerizable compounds, vinylphenyl-based radical polymerizable compounds, (meth)acrylic-based radical polymerizable compounds, allyl-based radical polymerizable compounds, and polybutadiene-based radical polymerizable compounds; radical polymerization initiators such as peroxide-based radical polymerization initiators and azo-based radical polymerization initiators; inorganic fillers such as silica particles; organic fillers such as rubber particles; organometallic compounds such as organocopper compounds and organozinc compounds; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as bentone and montmorillonite; silicone-based defoamers, acrylic defoamers, fluorine-containing compounds, and the like. Examples of the additives include antifoaming agents such as fluorine-based antifoaming agents and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silanes; 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. (G) Optional additives may be used singly or in combination of two or more.

[0134] <(H) Solvent> The resin composition may further contain a solvent (H) as a volatile component in addition to the nonvolatile components (A) to (G) described above.

[0135] As the (H) solvent, an organic solvent is usually used, for example, ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, γ-butyrolactone, etc.; ether-based solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether, etc.; alcohol-based solvents such as methanol, ethanol, propanol, butanol, ethylene glycol, etc.; 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, methyl methoxypropionate, etc. Examples of the solvent include ether ester 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 (H) solvent may be used alone or in combination of two or more.

[0136] The amount of (H) solvent is preferably set so as to adjust the melt viscosity of the resin composition within an appropriate range. The amount of (H) solvent may be, for example, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.1% by mass or less, or 0.01% by mass or less, relative to 100% by mass of nonvolatile components in the resin composition. It is particularly preferable that the resin composition does not contain (H) solvent. When the amount of (H) solvent is small, the generation of voids due to evaporation of (H) solvent can be suppressed. Furthermore, the handleability and workability of the resin composition can be improved.

[0137] <Characteristics of resin composition> The above-described resin composition can be cured by heat. Therefore, a cured product of the resin composition can be obtained by thermally curing the resin composition. Generally, among the components contained in the resin composition, volatile components such as (H) solvent can be volatilized by the heat during thermal curing, but non-volatile components such as components (A) to (G) do not volatilize by 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.

[0138] The resin composition according to the present embodiment can provide a cured product having a low melt viscosity, a high relative magnetic permeability, and a low magnetic loss. In general, the cured product of the resin composition according to the present embodiment has a lower melt viscosity than a cured product of a conventional resin composition containing an Fe-Ni-based alloy magnetic powder that does not contain Si or Cr, and a conventional resin composition containing an Fe-Ni-Si-based alloy magnetic powder that does not contain Cr.

[0139] Therefore, the resin composition can provide a cured product with high relative magnetic permeability. For example, when the relative magnetic permeability of a cured product obtained by thermally curing the resin composition at 190°C for 90 minutes is measured at a measurement frequency of 20 MHz and a room temperature of 23°C, the relative magnetic permeability is preferably 23 or more, more preferably 23.5 or more, and particularly preferably 24 or more. There is no particular upper limit to the relative magnetic permeability, and it can be, for example, 35 or less, or 30 or less. The relative magnetic permeability of the cured product can be measured by the method described in the Examples below.

[0140] Furthermore, the resin composition can produce a cured product with 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. For example, when the loss factor tan δ of a cured product obtained by thermally curing a resin composition at 190°C for 90 minutes is measured at a measurement frequency of 20 MHz and a room temperature of 23°C, the loss factor tan δ is preferably 0.04 or less, more preferably 0.038 or less, and particularly preferably 0.035 or less. There is no particular restriction on the lower limit of the loss factor, and it can be, for example, 0.00001 or more. The loss factor tan δ of the cured product can be measured by the method described in the Examples below.

[0141] The resin composition has a low melt viscosity. This allows the resin composition to be easily filled into holes without dissolving it in a solvent or the like. The melt viscosity is preferably 30,000 poise or less, more preferably 25,000 poise or less, and even more preferably 23,000 poise or less. There is no particular upper limit, and it can be, for example, 100 poise or more. The melt viscosity can be measured by the method described in the examples below.

[0142] Crystalline alloy powders, such as alloy powders containing Fe and Ni, generally have a high relative magnetic permeability, but tend to have a large magnetic loss. They also tend to have a high melt viscosity. Therefore, it has been difficult to obtain a cured resin composition with a low melt viscosity, a high relative magnetic permeability, and a small magnetic loss. In view of these conventional circumstances, the effects of the present invention are industrially beneficial.

[0143] There are no particular limitations on the properties of the resin composition. Therefore, the resin composition may be in a solid state or in a paste state having fluidity. For example, the resin composition may be made into a paste-like resin composition using a solvent, or may be made into a solvent-free paste-like resin composition by using a liquid thermosetting resin such as a liquid epoxy resin. When the resin composition contains a small amount of solvent, or when the resin composition does not contain a solvent, it is possible to suppress the generation of voids due to solvent evaporation, and further, it is possible to achieve excellent handleability and workability.

[0144] Taking advantage of the excellent properties described above, the resin composition is preferably used as a resin composition for manufacturing an inductor. For example, the resin composition described above is preferably used as a hole-filling resin composition for filling holes in a substrate provided in a circuit board. Furthermore, for example, the resin composition described above is also preferably used to form a cured product layer on a circuit board. To facilitate application to these uses, the resin composition may be used in the form of a paste or in the form of a resin sheet including a layer of the resin composition.

[0145] <Method of manufacturing resin composition> A resin composition according to one embodiment of the present invention can be produced, for example, by mixing the above-described components. The above-described components may be mixed partially or entirely at the same time, or may be mixed sequentially. The temperature may be appropriately set during the process of mixing the components, and thus heating and / or cooling may be performed temporarily or throughout. Furthermore, stirring or shaking may be performed during the process of mixing the components. Furthermore, degassing may be performed under low-pressure conditions, such as under vacuum.

[0146] <Magnetic paste> A magnetic paste according to one embodiment of the present invention includes the resin composition described above. The magnetic paste is typically a fluid paste containing the resin composition, and is therefore suitable for use in filling holes by printing. This magnetic paste may contain only the resin composition described above, or may contain any other component in combination with the resin composition. Preferably, the paste-like resin composition itself can be used as the magnetic paste.

[0147] The magnetic paste is preferably in a paste form at 23°C. The viscosity of this magnetic paste 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. "RE-80U" with a 3° x R9.7 rotor) under measurement conditions of a measurement sample volume of 0.22 ml and a rotation speed of 5 rpm.

[0148] <Resin sheet> A resin sheet according to one embodiment of the present invention includes a support and a resin composition layer provided on the support. The resin composition layer includes the resin composition described above, and preferably includes only the resin composition.

[0149] From the viewpoint of thinning, the thickness of the resin composition layer is preferably 250 μm or less, more preferably 200 μm or less. The lower limit of the thickness of the resin composition layer can be, for example, 5 μm or more, or 10 μm or more.

[0150] 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.

[0151] 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.

[0152] 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, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.).

[0153] The surface of the support that is to be bonded to the resin composition layer may be subjected to a matte treatment or a corona treatment.

[0154] The support may also be a support with a release layer, which has a release layer on the surface that bonds to 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 also be used as the support with a release layer, including PET films having a release layer primarily composed of a silicone-based release agent or an alkyd resin-based release agent, such as "PET501010," "SK-1," "AL-5," and "AL-7" manufactured by Lintec Corporation; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; and "Uni-Peel" manufactured by Unitika Limited.

[0155] The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, more preferably 10 μm to 60 μm. 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.

[0156] In the resin sheet, a protective film similar to that of the support may be provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite to the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. By providing the protective film, adhesion of dust and the like to the surface of the resin composition layer and scratches can be suppressed.

[0157] The resin sheet can be produced, for example, by applying the resin composition to a support using a die coater or the like to form a resin composition layer. If necessary, the resin composition may be mixed with an organic solvent and then applied to the support. When an organic solvent is used, drying may be performed after application, if necessary.

[0158] Drying may be carried out by, for example, heating, blowing hot air, or the like. Drying conditions are not particularly limited, but drying is carried out so that the content of organic solvent in the resin composition layer becomes 10% by mass or less, preferably 5% by mass or less. Although it varies depending on the components contained in the resin composition, a resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0159] The resin sheet can be stored in a rolled state. When the resin sheet has a protective film, it can usually be used by peeling off the protective film.

[0160] <Circuit board and its manufacturing method> The circuit board includes a cured product of the resin composition described above. The specific structure of the circuit board is not limited as long as it includes a cured product of the resin composition. A circuit board according to a first example includes a substrate having holes and a cured product of the resin composition filled in the holes. A circuit board according to a second example includes a cured product layer including a cured product of the resin composition. Below, manufacturing methods for the circuit boards according to the first and second examples will be explained. However, the circuit board and its manufacturing method are not limited to the first and second examples illustrated below.

[0161] <Circuit board according to the first example> A circuit board according to a first example includes a substrate having holes formed therein and a cured product of a resin composition filled in the holes. (1) filling holes in a substrate with a resin composition; and (2) a step of thermally curing the resin composition to obtain a cured product; The method for manufacturing a circuit board according to the first example further includes the steps of: (3) A step of polishing the surface of the cured product or resin composition (4) A step of subjecting the cured product to a roughening treatment; and (5) forming a conductive layer on the cured product; The steps (1) to (5) may be carried out in the order of step (1), step (2), step (3), step (4) and step (5), or step (2) may be carried out after step (3). In the method for producing a circuit board according to the first example, it is preferable to form a cured product using a paste-like resin composition. In the following explanation, an example will be given in which a board having through-holes formed therein as holes penetrating the board in the thickness direction is used.

[0162] <Process (1)> Step (1) typically includes preparing a substrate having through-holes formed therein. The substrate may be purchased from the market or may be manufactured using an appropriate material. An example method for manufacturing the substrate will now be described.

[0163] FIG. 1 is a cross-sectional view schematically illustrating a core substrate 10 prepared in a circuit board manufacturing method according to a first embodiment of the present invention. The substrate preparation step may include a step of preparing a core substrate 10, as in the example illustrated in FIG. 1 . The core substrate 10 typically includes a support substrate 11. Examples of the support substrate 11 include insulating substrates such as glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. A metal layer may be provided on the support substrate 11. The metal layer may be provided on one or both surfaces of the support substrate 11. Here, an example is shown in which metal layers 12 and 13 are provided on both surfaces of the support substrate 11. Examples of the metal layers 12 and 13 include layers formed of a metal such as copper. The metal layers 12 and 13 may be, for example, copper foil such as a carrier-attached copper foil, or may be metal layers formed from the material of the conductor layer described below.

[0164] FIG. 2 is a cross-sectional view schematically showing a core substrate 10 having a through hole 14 formed therein, in a method for manufacturing a circuit board according to a first embodiment of the present invention. As in the example shown in FIG. 2, the step of preparing a substrate may include a step of forming the through hole 14 in the core substrate 10. The through hole 14 can be formed by, for example, drilling, laser irradiation, plasma irradiation, or the like. Typically, the through hole 14 can be formed by drilling a through hole in the core substrate 10. As a specific example, the through hole 14 can be formed using a commercially available drilling machine. An example of a commercially available drilling machine is the "ND-1S211" manufactured by Hitachi Via Mechanics, Ltd.

[0165] FIG. 3 is a cross-sectional view schematically illustrating a core substrate 10 having a plating layer 20 formed in a through-hole 14 in a circuit board manufacturing method according to a first embodiment of the present invention. The substrate preparation process may include a process of roughening the core substrate 10 as needed, followed by forming the plating layer 20 as shown in FIG. 3 . The roughening process may be either a dry or wet roughening process. An example of a dry roughening process is plasma treatment. An example of a wet roughening process is a method in which a swelling process using a swelling liquid, a roughening process using an oxidizing agent, and a neutralization process using a neutralizing liquid are performed in this order. The plating layer 20 may be formed by a plating method. The procedure for forming the plating layer 20 by a plating method may be the same as that for forming the conductor layer in step (5) described below. Here, an example in which the plating layer 20 is formed in the through-hole 14 and on the surfaces of the metal layer 12 and the metal layer 13 will be described.

[0166] FIG. 4 is a cross-sectional view schematically illustrating how resin composition 30a is filled into through-holes in core substrate 10 in a method for manufacturing a circuit board according to a first example of one embodiment of the present invention. Step (1) includes preparing core substrate 10 having through-holes 14 formed therein as described above, and then filling through-holes 14 in core substrate 10 with resin composition 30a, as shown in FIG. 4. The filling can be performed by, for example, a printing method. Examples of printing methods include a method of printing resin composition 30a into through-holes 14 using a squeegee, a method of printing resin composition 30a using a cartridge, a method of printing resin composition 30a by mask printing, a roll coating method, an inkjet method, and the like.

[0167] <Process (2)> 5 is a schematic cross-sectional view illustrating step (2) of the method for manufacturing a circuit board according to a first example of one embodiment of the present invention. Step (2) includes filling through-holes 14 with resin composition 30a and then curing resin composition 30a to form a cured product 30 as shown in FIG.

[0168] The resin composition 30a is typically cured by thermal curing. The thermal curing conditions for the resin composition 30a can be appropriately set within a range in which the curing of the resin composition 30a 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 is 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 is preferably 120 minutes or shorter, more preferably 110 minutes or shorter, and even more preferably 100 minutes or shorter.

[0169] The degree of cure of the cured product 30 obtained in step (2) is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The degree of cure can be measured using, for example, a differential scanning calorimeter.

[0170] The method for manufacturing a circuit board according to the first example may include a step of heating resin composition 30a at a temperature lower than the curing temperature (preheating step) after filling through-holes 14 with resin composition 30a and before curing resin composition 30a. For example, prior to curing resin composition 30a, resin composition 30a may be preheated at a temperature of typically 50°C or higher and lower than 120°C (preferably 60°C or higher and 110°C or lower, more preferably 70°C or higher and 100°C or lower) for typically 5 minutes or longer (preferably 5 to 150 minutes, more preferably 15 to 120 minutes).

[0171] <Process (3)> FIG. 6 is a schematic cross-sectional view illustrating step (3) of a method for manufacturing a circuit board according to a first example of one embodiment of the present invention. When resin composition 30a is filled into through-hole 14 in step (1), excess resin composition 30a may protrude from or adhere to the outside of through-hole 14. Therefore, resin composition 30a may be provided not only within through-hole 14 but also outside of through-hole 14. Therefore, step (3) includes polishing the excess cured material 30 protruding from or adhering to core substrate 10, as shown in FIG. 6. Polishing removes the excess cured material 30, thereby flattening the surface of cured material 30. Furthermore, surface 31 of cured material 30 flattened by polishing typically forms a plane flush with surfaces 21 surrounding polished surface 31 (e.g., the surface of core substrate 10, the surface of plating layer 20).

[0172] The cured product 30 can be polished by any method capable of removing excess cured product 30 protruding from or adhering to the core substrate 10. Examples of such polishing methods include buff polishing, belt polishing, and ceramic polishing. An example of a commercially available buff polishing device is the "NT-700IM" manufactured by Ishii Hyoki Co., Ltd.

[0173] The arithmetic mean roughness (Ra) of the polished surface 31 (surface after curing) of the cured product 30 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 conductor 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.

[0174] The first example of the method for producing a circuit board may include a step of heat treating the cured product 30 after step (3) to further increase the degree of cure of the cured product 30. The temperature in the heat treatment may be the same as the curing temperature described above. Specific heat treatment temperatures are 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.

[0175] Furthermore, when step (3) is performed before step (2), a preheating treatment may be performed before step (3), in which the resin composition is heated at a temperature lower than the curing temperature. 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.

[0176] <Process (4)> Step (4) includes subjecting the cured product 30 to a roughening treatment (desmear treatment). The roughening treatment roughens the surface of the cured product 30. When the surface of the cured product 30 is polished, step (4) typically includes subjecting the polished surface 31 to a roughening treatment (desmear treatment). The procedure and conditions for the roughening treatment are not particularly limited, and for example, the procedure and conditions used in the manufacturing method of a multilayer printed wiring board can be adopted. As a specific example, the roughening treatment can be applied to the cured product 30 by performing a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing liquid in this order.

[0177] Examples of swelling solutions that can be used in the roughening step include alkaline solutions and surfactant solutions, with alkaline solutions being preferred. As alkaline solutions serving as swelling solutions, sodium hydroxide solutions and potassium hydroxide solutions are more preferred. Examples of commercially available swelling solutions include "Swelling Dip Securigans P" and "Swelling Dip Securigans SBU" manufactured by Atotech Japan.

[0178] The swelling treatment with a swelling liquid can be carried out, for example, by immersing the cured product 30 for 1 to 20 minutes in the swelling liquid at 30 to 90° C. From the viewpoint of keeping the swelling of the resin contained in the cured product 30 at an appropriate level, it is preferable to immerse the cured product 30 in the swelling liquid at 40 to 80° C. for 5 to 15 minutes.

[0179] Examples of oxidizing agents that can be used in the roughening treatment with an oxidizing agent include alkaline permanganate solutions prepared by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide. Roughening treatment with an oxidizing agent such as alkaline permanganate solution is preferably carried out by immersing the cured material 30 in an oxidizing agent solution heated to 60°C to 80°C for 10 to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% to 10% by mass. Commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact P" and "Dosing Solution Securigance P" manufactured by Atotech Japan.

[0180] The neutralizing solution used in the neutralization treatment is preferably an acidic aqueous solution. An example of a commercially available neutralizing solution is "Reduction Solution Securigance P" manufactured by Atotech Japan. Neutralization treatment with a neutralizing solution can be performed by immersing the surface roughened with an oxidizing solution in the neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From the standpoint of workability, etc., a preferred method is to immerse the cured product 30 roughened with an oxidizing solution in the neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

[0181] The arithmetic mean roughness (Ra) of the surface of the cured product 30 after roughening treatment 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 conductor layer. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and even more preferably 1000 nm or less. The surface roughness (Ra) can be measured, for example, using a non-contact surface roughness meter.

[0182] <Process (5)> Fig. 7 is a schematic cross-sectional view illustrating step (5) of the method for manufacturing a circuit board according to a first example of one embodiment of the present invention. Step (5), as shown in Fig. 7, involves forming a conductor layer 40 on the polished surface 31 of the cured product 30. Here, an example is shown in which the conductor layer 40 is formed not only on the polished surface 31 of the cured product 30 but also on the surrounding surfaces 21 (e.g., the surface of the core substrate 10, the surface of the plating layer 20). Also, Fig. 7 shows an example in which the conductor layer 40 is formed on both sides of the core substrate 10, but the conductor layer 40 may be formed on only one side of the core substrate 10.

[0183] 8 is a schematic cross-sectional view illustrating step (5) of the method for manufacturing a circuit board according to a first example of one embodiment of the present invention. As shown in FIG. 8, step (5) may include forming a conductor layer 40, and then removing parts of the conductor layer 40, the metal layer 12, the metal layer 13, and the plating layer 20 by etching or other processing to form a patterned conductor layer 41.

[0184] Examples of methods for forming the conductor layer 40 include plating, sputtering, and vapor deposition, with plating being preferred. In a preferred embodiment, the surface of the cured product 30 (and the plating layer 20) can be plated by an appropriate method such as a semi-additive method or a full-additive method to form a patterned conductor layer 41 having a desired wiring pattern. Examples of materials for the conductor layer 40 include simple metals such as gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium; and alloys of two or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. Among these, from the viewpoints of versatility, cost, ease of patterning, and the like, it is preferable to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or a nickel-chromium alloy, a copper-nickel alloy, or a copper-titanium alloy, it is more preferable to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or a nickel-chromium alloy, and it is even more preferable to use copper.

[0185] Here, an example of a method for forming a patterned conductor layer 41 on the polished surface 31 of the cured product 30 will be described in detail. A plating seed layer is formed on the polished surface 31 of the cured product 30 by electroless plating. Next, an electrolytic plating layer is formed on the formed plating seed layer by electrolytic plating. Thereafter, if necessary, unnecessary plating seed layer is removed by a process such as etching, thereby forming a patterned conductor layer 41 having a desired wiring pattern. After forming the patterned conductor layer 41, an annealing treatment may be performed as necessary to improve the adhesion strength of the patterned conductor layer 41. The annealing treatment can be performed, for example, by heating at 150 to 200°C for 20 to 90 minutes.

[0186] From the viewpoint of thinning, the thickness of the patterned conductor layer 41 is preferably 70 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less, still more preferably 40 μm or less, particularly preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The lower limit is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more.

[0187] By the above method, a circuit board 1 including a cured product 30 of the resin composition 30a can be produced.

[0188] <Circuit Board According to Second Example> The circuit board according to the second example includes a cured material layer containing a cured material of a resin composition. The cured material layer preferably contains only a cured material of the resin composition. The cured material layer is preferably formed using a resin sheet. This circuit board can be, for example, (i) forming a cured material layer on an inner layer substrate; (ii) drilling holes in the cured layer; (iii) roughening the surface of the cured layer; and (iv) forming a conductive layer on the surface of the cured material layer; It can be produced by a production method including the steps of:

[0189] <Process (i)> Step (i) includes forming a cured material layer on the inner layer substrate. Preferably, step (i) includes laminating a resin sheet on the inner layer substrate so that the resin composition layer is bonded to the inner layer substrate to form a cured material layer. For example, the resin sheet is laminated on the inner layer substrate so that the resin composition layer is bonded to the inner layer substrate, and the resin composition layer is thermally cured to form a cured material layer.

[0190] 9 is a schematic cross-sectional view illustrating step (i) in a method for manufacturing a circuit board according to a second embodiment of the present invention. As shown in FIG. 9, a resin sheet 310 is prepared, which includes a support 330 and a resin composition layer 320a provided on the support 330. Then, the resin sheet 310 and the inner substrate 200 are laminated together so that the resin composition layer 320a is bonded to the inner substrate 200.

[0191] An insulating substrate can be used as the inner layer substrate 200. Examples of the inner layer substrate 200 include insulating base materials such as a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, and a thermosetting polyphenylene ether substrate. The inner layer substrate 200 may be an inner layer circuit board having wiring and the like built into its thickness.

[0192] The inner substrate 200 shown in this example includes a first conductor layer 420 provided on the first main surface 200a and an external terminal 240 provided on the second main surface 200b. The first conductor layer 420 may include multiple wirings. However, in the example shown in FIG. 9, only the wirings constituting the coil-shaped conductive structure 400 of the inductor element (see FIG. 12) are shown. The external terminal 240 may be a terminal for electrically connecting to an external device or the like (not shown). The external terminal 240 may be configured as a part of the conductor layer provided on the second main surface 200b.

[0193] Conductive materials that can form the first conductor layer 420 and the external terminals 240 include, for example, the same materials as those for the conductor layers described in the first example.

[0194] The first conductor layer 420 and the external terminal 240 may have a single-layer structure or a multi-layer structure in which two or more single metal layers or alloy layers made of different types of metals or alloys are stacked. The thickness of the first conductor layer 420 and the external terminal 240 may be the same as that of the second conductor layer 440 described below.

[0195] The line (L) / space (S) ratio of the first conductor layer 420 and the external terminal 240 is not particularly limited, but from the viewpoint of reducing surface irregularities and obtaining a cured layer with excellent smoothness, it is usually 900 / 900 μm or less, preferably 700 / 700 μm or less, more preferably 500 / 500 μm or less, even more preferably 300 / 300 μm or less, and still more preferably 200 / 200 μm or less. The lower limit of the line / space ratio is not particularly limited, but from the viewpoint of improving the embedding of the resin composition layer in the spaces, it is preferably 1 / 1 μm or more.

[0196] The inner substrate 200 may have a plurality of through holes 220 that penetrate the inner substrate 200 from the first main surface 200a to the second main surface 200b. The through holes 220 are provided with internal through-hole wiring 220a. The internal through-hole wiring 220a electrically connects the first conductor layer 420 and the external terminal 240.

[0197] The resin composition layer 320a and the inner substrate 200 can be bonded, for example, by thermocompression bonding the resin sheet 310 to the inner substrate 200 from the support 330 side. Examples of a member for thermocompression bonding the resin sheet 310 to the inner substrate 200 (hereinafter also referred to as a "thermocompression member") include a heated metal plate (such as a stainless steel (SUS) plate) or a metal roll (SUS roll). Note that rather than pressing the resin sheet 310 by directly contacting it with the thermocompression member, it is preferable to press the resin sheet 310 via a sheet made of an elastic material such as heat-resistant rubber so that the resin sheet 310 can sufficiently conform to the irregularities on the surface of the inner substrate 200.

[0198] 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 0.098MPa to 1.77MPa, more preferably 0.29MPa to 1.47MPa, and 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 substrate are preferably bonded under reduced pressure conditions of 26.7hPa or less.

[0199] The resin composition layer 320a of the resin sheet 310 can be bonded to the inner layer substrate 200 using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd. and a vacuum applicator manufactured by Nikko Materials Co., Ltd.

[0200] After bonding the resin sheet 310 and the inner layer substrate 200, the laminated resin sheet 310 may be smoothed under normal pressure (atmospheric pressure), for example, by pressing a thermocompression member from the support 330 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.

[0201] 10 is a schematic cross-sectional view illustrating step (i) in a method for manufacturing a circuit board according to a second embodiment of the present invention. After laminating the resin sheet 310 on the inner substrate 200, the resin composition layer 320a is cured to form a cured layer. In this example, as shown in FIG. 10, the resin composition layer 320a bonded to the inner substrate 200 is thermally cured to form the first cured layer 320.

[0202] The thermal curing conditions for the resin composition layer 320a 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 is 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 is preferably 120 minutes or shorter, more preferably 110 minutes or shorter, and even more preferably 100 minutes or shorter.

[0203] The support 330 may be removed between the end of the thermal curing in step (i) and the step (ii), or may be peeled off after the step (ii).

[0204] The arithmetic mean roughness (Ra) of the cured layer before roughening treatment 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 plating. 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.

[0205] In step (i), instead of using a resin sheet, a resin composition may be applied to the inner layer substrate 200 using a die coater or the like, and then thermally cured to form a cured layer.

[0206] <Process (ii)> Fig. 11 is a schematic cross-sectional view illustrating step (ii) in a method for manufacturing a circuit board according to a second example of one embodiment of the present invention. As shown in Fig. 11, step (ii) includes drilling the first cured material layer 320 to form via holes 360. The via holes 360 form paths for electrically connecting the first conductor layer 420 and the second conductor layer 440 described below. The via holes 360 may be formed using, for example, a drill, a laser, plasma, or the like. The dimensions and shape of the holes may be determined appropriately depending on the design of the printed wiring board.

[0207] <Step (iii)> In step (iii), the surface of the cured material layer having the via holes formed therein is roughened by the same method as that described in step (4) of the first example.

[0208] The arithmetic mean roughness (Ra) of the cured layer after roughening treatment 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 plating. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and even more preferably 1000 nm or less. The surface roughness (Ra) can be measured, for example, using a non-contact surface roughness meter.

[0209] <Process (iv)> 12 is a schematic cross-sectional view illustrating step (iv) in a method for producing a circuit board according to a second embodiment of the present invention. As shown in FIG. 12, in step (iv), a second conductor layer 440 is formed on a first cured material layer 320.

[0210] Conductive materials that can form the second conductor layer 440 include, for example, the same materials as those of the conductor layer described in the first example.

[0211] From the viewpoint of thinning, the thickness of the second conductor layer 440 is preferably 70 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less, still more preferably 40 μm or less, particularly preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The lower limit is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more.

[0212] The second conductor layer 440 can be formed by plating. The second conductor layer 440 is preferably formed by a wet plating method such as a semi-additive method or a full-additive method including an electroless plating process, a mask pattern formation process, an electrolytic plating process, and a flash etching process. By forming the second conductor layer 440 using a wet plating method, it is possible to form the second conductor layer 440 including a desired wiring pattern. Note that this process also forms via-hole wiring 360a in the via hole 360.

[0213] The first conductor layer 420 and the second conductor layer 440 may be provided in a spiral shape, for example, as shown in Figures 13 to 15 described later. In one example, one end of the spiral wiring portion of the second conductor layer 440 on the central side is electrically connected to one end of the spiral wiring portion of the first conductor layer 420 on the central side by via-hole wiring 360a. The other end of the spiral wiring portion of the second conductor layer 440 on the outer periphery is electrically connected to land 420a of the first conductor layer 420 by via-hole wiring 360a. Therefore, the other end of the spiral wiring portion of the second conductor layer 440 on the outer periphery is electrically connected to external terminal 240 via via-hole wiring 360a, land 420a, and through-hole wiring 220a.

[0214] The coil-shaped conductive structure 400 is composed of a spiral wiring portion that is part of the first conductor layer 420, a spiral wiring portion that is part of the second conductor layer 440, and via-hole wiring 360a that electrically connects the spiral wiring portion of the first conductor layer 420 and the spiral wiring portion of the second conductor layer 440.

[0215] After step (iv), a step of forming a cured material layer on the conductor layer may be performed. Specifically, as shown in FIG. 14, a second cured material layer 340 is formed on a first cured material layer 320 on which a second conductor layer 440 and via-hole wiring 360a have been formed. The second cured material layer may be formed by a process similar to the process already described. By the above method, a circuit board 100 including a first cured material layer 320 and a second cured material layer 340 formed from a cured product of a resin composition can be manufactured.

[0216] <Inductor board> The inductor substrate includes the circuit board described above. When such an inductor substrate includes a circuit board obtained by the circuit board manufacturing method according to the first example described above, it may have an inductor pattern formed of a conductor around at least a portion of the periphery of the cured product of the resin composition. In this case, the inductor substrate may include, for example, an inductor element configured by an inductor pattern formed of at least a portion of the metal layer 12, the metal layer 13, the plating layer 20, and the patterned conductor layer 41, and a core formed of the cured product 30 surrounded by this inductor pattern. For example, an inductor substrate such as that described in JP 2016-197624 A can be used.

[0217] Furthermore, when the inductor substrate includes a circuit board obtained by the circuit board manufacturing method according to the second example, the inductor substrate may have a cured material layer and a conductive structure at least partially embedded in the cured material layer, and the inductor substrate may include an inductor element constituted by the conductive structure and a portion of the cured material layer that extends in the thickness direction of the cured material layer and is surrounded by the conductive structure.

[0218] Fig. 13 is a schematic plan view of the circuit board 100 included in the inductor substrate, viewed from one side in the thickness direction. Fig. 14 is a schematic view showing a cut end surface of the circuit board 100 cut at the position indicated by the dashed dotted line II-II in Fig. 13. Fig. 15 is a schematic plan view for explaining the configuration of the first conductor layer 420 of the circuit board 100 included in the inductor substrate.

[0219] As shown in Figures 13 and 14 as an example, the circuit board 100 may be a board having multiple cured material layers (first cured material layer 320, second cured material layer 340) and multiple conductor layers (first conductor layer 420, second conductor layer 440). Thus, in the example shown here, the circuit board 100 may be a build-up wiring board having build-up cured material layers and build-up conductor layers. The circuit board 100 also includes an inner layer board 200.

[0220] 14, the first cured material layer 320 and the second cured material layer 340 constitute the magnetic part 300, which can be seen as an integrated cured material layer. Therefore, the coiled conductive structure 400 is provided so that at least a portion thereof is embedded in the magnetic part 300. That is, in the circuit board 100 shown in this example, the inductor element is constituted by the coiled conductive structure 400 and a core portion that extends in the thickness direction of the magnetic part 300 and is a portion of the magnetic part 300 surrounded by the coiled conductive structure 400.

[0221] 15, the first conductor layer 420 includes a spiral wiring portion for constituting the coil-shaped conductive structure 400 and a rectangular land 420a electrically connected to the through-hole wiring 220a. In the example shown here, the spiral wiring portion includes a straight portion, a bent portion bent at a right angle, and a detour portion that detours around the land 420a. The spiral wiring portion of the first conductor layer 420 has an overall outline that is approximately rectangular, and has a shape that winds counterclockwise from the center toward the outside.

[0222] Similarly, a second conductor layer 440 is provided on the first cured material layer 320. The second conductor layer 440 includes a spiral wiring portion for configuring the coil-shaped conductive structure 400. In Fig. 13 or 14, the spiral wiring portion includes a straight portion and a bent portion bent at a right angle. In Fig. 13 or 14, the spiral wiring portion of the second conductor layer 44 has an overall outline that is approximately rectangular, and has a shape that is wound clockwise from the center toward the outside.

[0223] The inductor substrate described above can be used as a wiring board for mounting electronic components such as semiconductor chips, and can also be used as a (multilayer) printed wiring board using such a wiring board as an inner layer substrate.Furthermore, such a wiring board can be used as an individual chip inductor component, and can also be used as a printed wiring board with the chip inductor component surface-mounted.

[0224] Furthermore, various types of semiconductor devices can be manufactured using such a wiring board. Semiconductor devices including such wiring boards can be suitably used in electrical appliances (e.g., computers, mobile phones, digital cameras, televisions, etc.) and vehicles (e.g., motorcycles, automobiles, trains, ships, aircraft, etc.). [Example]

[0225] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples. In the following, "%" and "parts" representing amounts mean "% by mass" and "parts by mass" unless otherwise specified. Furthermore, unless otherwise specified, the temperature condition is room temperature (23°C). Furthermore, unless otherwise specified, the pressure condition is normal pressure (1 atm).

[0226] <Example 1: Production of varnish-like resin composition 1> Fe-Ni-Si-Cr alloy magnetic powder (Mitsubishi Steel "AKT-PB-1Si-3Cr", alloy of Fe 50%, Ni 46%, Si 1%, Cr 3%), average particle size (D 50 )5μm, true density 8.0g / cm 3 ) 150.0 mass parts, magnetic powder ("MZ03S" manufactured by Powder Tech Co., Ltd., Mn-Zn ferrite powder, average particle size (D 50 )0.5μm, true density 5.1g / cm 3 ) 30.0 parts by mass, epoxy resin (Nippon Steel Chemical & Material Co., Ltd. "ZX-1059", a mixture of bisphenol A epoxy resin and bisphenol F epoxy resin, epoxy equivalent 169 g / eq., true density 1.2 g / cm 3 ) 3.7 parts by mass, phenolic resin (DIC Corporation "LA-7054", aminotriazine-modified phenolic novolac resin, MEK solution with 60% non-volatile components, hydroxyl group equivalent 125 g / eq., true density of non-volatile components 1.2 g / cm 3 ) 4.2 parts by mass, phenoxy resin (Mitsubishi Chemical Corporation "YX7553BH30", a solution of methyl ethyl ketone:cyclohexanone = 1:1 with 30% non-volatile components, a special skeleton phenoxy resin, true density of the non-volatile component 1.2 g / cm 3) 1.1 parts by mass, dispersant (Ajinomoto Fine-Techno Co., Ltd. "PB-881", polyester-based dispersant, true density 1.2 g / cm 3 ) and 0.8 parts by mass of a curing accelerator ("2E4MZ" manufactured by Shikoku Chemicals Corporation, an imidazole-based curing accelerator with a true density of 1.2 g / cm 3 ) was uniformly dispersed in 0.1 parts by mass of a solvent (methyl ethyl ketone) and 6.7 parts by mass of a solvent to prepare a varnish-like resin composition 1.

[0227] Example 2: Preparation of varnish-like resin composition 2 In Example 1, 1) Fe-Ni-Si-Cr alloy magnetic powder (Mitsubishi Steel "AKT-PB-1Si-3Cr", alloy of Fe 50%, Ni 46%, Si 1%, Cr 3%, average particle size (D 50 )5μm, true density 8.0g / cm 3 ) from 150.0 parts by mass to 133.6 parts by mass, 2) Magnetic powder (MZ03S manufactured by Powder Tech Co., Ltd., Mn-Zn ferrite powder, average particle size (D 50 )0.5μm, true density 5.1g / cm 3 The amount of ) was changed from 30.0 parts by mass to 40.0 parts by mass. A varnish-like resin composition 2 was prepared in the same manner as in Example 1 except for the above.

[0228] Example 3: Preparation of varnish-like resin composition 3 In Example 1, 1) Fe-Ni-Si-Cr alloy magnetic powder (Mitsubishi Steel "AKT-PB-1Si-3Cr", alloy of Fe 50%, Ni 46%, Si 1%, Cr 3%, average particle size (D 50 )5μm, true density 8.0g / cm 3 ) from 150.0 parts by mass to 116.1 parts by mass, 2) Magnetic powder (MZ03S manufactured by Powder Tech Co., Ltd., Mn-Zn ferrite powder, average particle size (D 50 )0.5μm, true density 5.1g / cm 3 The amount of ) was changed from 30.0 parts by mass to 51.4 parts by mass. A varnish-like resin composition 3 was prepared in the same manner as in Example 1, except for the above.

[0229] Example 4: Preparation of varnish-like resin composition 4 In Example 1, 1) Fe-Ni-Si-Cr alloy magnetic powder (Mitsubishi Steel "AKT-PB-1Si-3Cr", alloy of Fe 50%, Ni 46%, Si 1%, Cr 3%, average particle size (D 50 )5μm, true density 8.0g / cm 3 ) from 150.0 parts by mass to 98.3 parts by mass, 2) Magnetic powder (MZ03S manufactured by Powder Tech Co., Ltd., Mn-Zn ferrite powder, average particle size (D 50 )0.5μm, true density 5.1g / cm 3 The amount of ) was changed from 30.0 parts by mass to 61.7 parts by mass. A varnish-like resin composition 4 was prepared in the same manner as in Example 1 except for the above.

[0230] Example 5: Preparation of varnish-like resin composition 5 In Example 2, magnetic powder ("MZ03S" manufactured by Powder Tech Co., Ltd., Mn-Zn ferrite powder, average particle size (D 50 )0.5μm, true density 5.1g / cm 3 ) 40.0 mass parts of magnetic powder ("M03S" manufactured by Powder Tech Co., Ltd., Mn-based ferrite powder, average particle size (D 50 )0.5μm, true density 5.0g / cm 3 ) was changed to 40.0 parts by mass. A varnish-like resin composition 5 was prepared in the same manner as in Example 2, except for the above.

[0231] Example 6: Preparation of varnish-like resin composition 6 In Example 2, Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-1Si-3Cr" manufactured by Mitsubishi Steel Corporation, an alloy of 50% Fe, 4% Ni, 1% Si, and 3% Cr, with an average particle size (D 50 )5μm, true density 8.0g / cm 3) 133.6 mass parts of Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-3Si-4Cr" manufactured by Mitsubishi Steel Corporation, alloy of Fe 47%, Ni 46%, Si 3%, Cr 4%, average particle size (D 50 )5μm, true density 8.0g / cm 3 ) was changed to 133.6 parts by mass. A varnish-like resin composition 6 was prepared in the same manner as in Example 2, except for the above points.

[0232] Example 7: Preparation of varnish-like resin composition 7 In Example 2, Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-1Si-3Cr" manufactured by Mitsubishi Steel Corporation, an alloy of 50% Fe, 4% Ni, 1% Si, and 3% Cr, with an average particle size (D 50 )5μm, true density 8.0g / cm 3 ) 133.6 mass parts of Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-0.2Si-3Cr" manufactured by Mitsubishi Steel Corporation, alloy of Fe 50.8%, Ni 46%, Si 0.2%, Cr 3%, average particle size (D 50 )5μm, true density 8.0g / cm 3 ) was changed to 133.6 parts by mass. Varnish-like resin composition 7 was prepared in the same manner as in Example 2, except for the above points.

[0233] Example 8: Preparation of varnish-like resin composition 8 In Example 2, Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-1Si-3Cr" manufactured by Mitsubishi Steel Corporation, an alloy of 50% Fe, 4% Ni, 1% Si, and 3% Cr, with an average particle size (D 50 )5μm, true density 8.0g / cm 3 ) 133.6 mass parts of Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-1Si-1Cr" manufactured by Mitsubishi Steel Corporation, alloy of Fe 52%, Ni 46%, Si 1.0%, Cr 1.0%, average particle size (D 50 )5μm, true density 8.0g / cm 3 ) was changed to 133.6 parts by mass. A varnish-like resin composition 8 was prepared in the same manner as in Example 2, except for the above points.

[0234] Example 9: Preparation of varnish-like resin composition 9 In Example 2, Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-1Si-3Cr" manufactured by Mitsubishi Steel Corporation, an alloy of 50% Fe, 4% Ni, 1% Si, and 3% Cr, with an average particle size (D 50 )5μm, true density 8.0g / cm 3 ) 133.6 mass parts of Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-1Si-6Cr" manufactured by Mitsubishi Steel Corporation, alloy of Fe 47%, Ni 46%, Si 1.0%, Cr 6.0%, average particle size (D 50 )5μm, true density 8.0g / cm 3 ) was changed to 133.6 parts by mass. A varnish-like resin composition 9 was prepared in the same manner as in Example 2, except for the above.

[0235] Comparative Example 1: Preparation of Varnish-like Resin Composition 10 In Example 2, Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-1Si-3Cr" manufactured by Mitsubishi Steel Corporation, an alloy of 50% Fe, 4% Ni, 1% Si, and 3% Cr, with an average particle size (D 50 )5μm, true density 8.0g / cm 3 ) 133.6 mass parts of Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-1Si-8Cr" manufactured by Mitsubishi Steel Corporation, alloy of Fe 45%, Ni 46%, Si 1.0%, Cr 8.0%, average particle size (D 50 )5μm, true density 8.0g / cm 3 ) was changed to 133.6 parts by mass. A varnish-like resin composition 10 was prepared in the same manner as in Example 2, except for the above points.

[0236] Comparative Example 2: Preparation of Varnish-like Resin Composition 11 In Example 2, Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-1Si-3Cr" manufactured by Mitsubishi Steel Corporation, an alloy of 50% Fe, 4% Ni, 1% Si, and 3% Cr, with an average particle size (D 50 )5μm, true density 8.0g / cm 3) 133.6 parts by mass of Fe-Ni-Si alloy magnetic powder (Epson Atmix "50FE50%NI PF-5F", an alloy of Fe 49%, Ni 50%, and Si 0.4%, with an average particle size (D 50 )5μm, true density 8.0g / cm 3 ) was changed to 133.6 parts by mass. A varnish-like resin composition 11 was prepared in the same manner as in Example 2, except for the above points.

[0237] <Comparative Example 3: Preparation of Varnish-like Resin Composition 13> In Example 2, Fe-Ni-Si-Cr alloy magnetic powder ("AKT-PB-1Si-3Cr" manufactured by Mitsubishi Steel Corporation, an alloy of 50% Fe, 4% Ni, 1% Si, and 3% Cr, with an average particle size (D 50 )5μm, true density 8.0g / cm 3 ) 133.6 mass parts of Fe-Ni-Mo alloy magnetic powder ("AKT-78Ni-5Mo" manufactured by Mitsubishi Steel Corporation, an alloy of Fe 17%, Ni 78%, and Mo 5%, with an average particle size (D 50 )5μm, true density 8.9g / cm 3 ) was changed to 133.6 parts by mass. A varnish-like resin composition 12 was prepared in the same manner as in Example 2, except for the above points.

[0238] Comparative Example 4: Preparation of Varnish-like Resin Composition 14 In Example 2, 1) Fe-Ni-Si-Cr alloy magnetic powder (Mitsubishi Steel "AKT-PB-1Si-3Cr", alloy of Fe 50%, Ni 4%, Si 1%, Cr 3%, average particle size (D 50 )5μm, true density 8.0g / cm 3 ) 133.6 mass parts of Fe-Si-Cr alloy magnetic powder (Epson Atmix "AW2-08PF3F", an alloy of Fe-Si-Cr, average particle size (D 50 )3.5μm, true density 7.0g / cm 3 ) to 100.0 parts by mass, 2) Magnetic powder (MZ03S manufactured by Powder Tech Co., Ltd., Mn-Zn ferrite powder, average particle size (D 50 )0.5μm, true density 5.1g / cm 3The amount of ) was changed from 40.0 parts by mass to 51.4 parts by mass. A varnish-like resin composition 13 was prepared in the same manner as in Example 2, except for the above points.

[0239] <Manufacturing of resin sheets> A PET film ("Lumirror R80" manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130°C) that had been release-treated with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation) was prepared as a support. The varnish-like resin compositions (resin varnishes) prepared in the Examples and Comparative Examples were applied to the support using a die coater so that the thickness of the resin composition layer after drying was 70 μm, and the film was dried at 90°C for 5 minutes to obtain a resin sheet.

[0240] <Production of sheet-shaped cured body> The resin sheet was cut into 200 mm square pieces. The cut resin sheet (200 mm square) was laminated onto 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") so that the resin composition layer was in contact with the center of the smooth surface of the polyimide film. Lamination was performed by reducing the pressure to 13 hPa or less for 30 seconds, followed by pressure bonding at 100 °C and a pressure of 0.74 MPa for 30 seconds. This resulted in a multilayer film having a layer structure of support / resin composition layer / polyimide film.

[0241] After the support was peeled off, the resin composition layer was thermally cured by heating for 90 minutes at 190° C. Thereafter, the polyimide film was peeled off to obtain a sheet-like cured product of the resin composition.

[0242] <Measurement of relative permeability and loss factor> The resulting sheet-like cured product was cut into doughnut-shaped evaluation samples 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 these evaluation samples 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'".

[0243] The evaluation criteria for relative permeability are as follows: "Good": Relative permeability is 23 or more. "×": Relative permeability is less than 23.

[0244] The evaluation criteria for the loss factor are as follows: "Good": Loss coefficient is 0.05 or less. "×": Loss coefficient exceeds 0.05.

[0245] <Evaluation of melt viscosity> After peeling off the support from the resin sheet, the resin composition layer was compressed in a mold to prepare a measurement pellet (18 mm diameter, 3.5 g to 3.7 g). The minimum melt viscosity of this measurement pellet was then measured using a dynamic viscoelasticity measuring device (Rheosol-G3000, manufactured by UBM). Specifically, for 1 g of the measurement pellet, a parallel plate with a diameter of 18 mm was used to measure the dynamic viscoelastic modulus by increasing the temperature from a starting temperature of 60°C to 200°C, and the minimum melt viscosity (poise) was calculated. The measurement conditions were a temperature increase rate of 5°C / min, a measurement temperature interval of 2.5°C, a frequency of 1 Hz, and a strain of 1 deg. The evaluation criteria for melt viscosity were as follows: "Good": Melt viscosity is 30,000 poise or less. "X": The melt viscosity exceeds 30,000 poise.

[0246] [Table 1] *The total amount (mass%) of component (A) and component (C) represents the amount relative to 100 mass% of nonvolatile components in the resin composition, and the total amount (volume%) of component (A) and component (C) represents the amount relative to 100 volume% of nonvolatile components in the resin composition.

[0247] In Examples 1 to 9, it was confirmed that even when components (C) to (G) were not contained, the same results as in the above Examples were obtained, although to different degrees. [Explanation of symbols]

[0248] 1 circuit board 10 Core Board 11 Support substrate 12 metal layer 13 Metal layer 14 through holes 20 plating layer 21 Surface surrounding the polished surface 30 Cured product 30a Resin composition 31 Polished surface of hardened material (polished surface) 40 Conductor Layer 41 Patterned conductor layer 100 Circuit Boards 200 inner layer board 200a 1st main surface 200b 2nd main surface 220 through hole 220a Through-hole wiring 240 External terminal 310 Resin Sheet 320 1st cured material layer 320a Resin composition layer 330 Support 360 Beer Hall 360a via hole wiring 400 Coil-shaped conductive structure 420 First conductor layer 420a Land 440 Second conductor layer

Claims

1. (A) Fe—Ni—Si—Cr crystalline alloy magnetic powder, and (B) a thermosetting resin, the content of Cr contained in the component (A) is 0.1% by mass or more and 6% by mass or less, relative to 100% by mass of the component (A); the content of Si contained in the component (A) is 0.1% by mass or more and 5% by mass or less, relative to 100% by mass of the component (A); A resin composition, wherein the amount of component (A) is 40% by mass or more relative to 100% by mass of nonvolatile components in the resin composition.

2. 2. The resin composition according to claim 1, further comprising (C) a magnetic powder other than the Fe-Ni-Si-Cr crystalline alloy magnetic powder.

3. The resin composition according to claim 2 , wherein the component (C) comprises a ferrite-based magnetic powder.

4. 3. The resin composition according to claim 2, wherein the component (C) comprises a ferrite-based magnetic powder containing at least one element selected from the group consisting of Mn, Zn, Ni, and Cu.

5. The resin composition according to claim 2, wherein the component (C) has an average particle size smaller than that of the component (A).

6. The resin composition according to claim 1, wherein the component (B) comprises an epoxy resin (B-1).

7. The resin composition according to claim 1, wherein the component (B) includes a curing agent (B-2).

8. The resin composition according to claim 1 , further comprising (E) a dispersant.

9. The resin composition according to claim 1 , further comprising (F) a curing accelerator.

10. The resin composition according to claim 1, wherein the content of Si contained in the component (A) is 0.2% by mass or more and 5% by mass or less, relative to 100% by mass of the component (A).

11. The resin composition according to claim 1, wherein the content of Cr contained in the component (A) is 0.5% by mass or more and 6% by mass or less, based on 100% by mass of the component (A).

12. The resin composition according to claim 1, wherein the amount of component (A) is 30% by volume or more relative to 100% by volume of nonvolatile components in the resin composition.

13. The resin composition according to claim 2, wherein the total amount of the components (A) and (C) is 70% by mass or more relative to 100% by mass of the nonvolatile components in the resin composition.

14. 3. The resin composition according to claim 2, wherein the total amount of the components (A) and (C) is 50% by volume or more relative to 100% by volume of the nonvolatile components in the resin composition.

15. The resin composition according to claim 1, which is used for hole filling.

16. A cured product of the resin composition according to any one of claims 1 to 15.

17. A magnetic paste comprising the resin composition according to any one of claims 1 to 15.

18. A support and a resin composition layer provided on the support, A resin sheet, wherein the resin composition layer comprises the resin composition according to any one of claims 1 to 15.

19. A circuit board comprising: a substrate having a hole; and a cured product of the resin composition according to any one of claims 1 to 15 filled in the hole.

20. A circuit board comprising a cured product layer containing a cured product of the resin composition according to any one of claims 1 to 15.

21. An inductor substrate comprising the circuit board of claim 19.

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