Resin composition

Abstract

To provide a resin composition that has low thixotropy and superior filling properties, and can give a cured product having high relative permeability.SOLUTION: A resin composition comprises: (A) an alloy magnetic powder having a BET specific surface area SA of 2 m2 / g or more and 10 m2 / g or less; (B) a magnetic powder having a BET specific surface area SB of 0.1 m2 / g or more and less than 2 m2 / g; and (C) a binder resin.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition containing magnetic powder.

Background Art

[0002] Inductor elements are widely mounted on information terminals such as mobile phones and smartphones. In recent years, a method of forming a coil by a conductor pattern on a substrate and providing an inductor element inside the substrate has been sometimes performed. As a method for forming these inductor elements, a method using a resin composition containing magnetic powder is known. For example, a paste-like resin composition for filling holes such as through-holes, a film-like resin composition for forming a magnetic layer, etc. are known (Patent Document 1, Patent Document 2).

[0003] In recent years, in order to further improve the performance of inductor elements, it has been required to further improve the magnetic properties of magnetic materials. As a method for improving the magnetic properties of magnetic materials, a method of increasing the content of magnetic powder in the material can be considered. For example, a technique is known in which by using two or more types of magnetic metal powders having different average particle diameters, the packing rate of the powder is improved and the magnetic properties are enhanced (Patent Document 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the case of conventional resin compositions, when the filling rate of magnetic powder was increased, the thixotropy of the resin composition tended to increase. When the thixotropy of the resin composition was high, in the case of hole filling applications such as filling holes such as through holes with the paste-like resin composition, the embedding property might be poor. Further, when the thixotropy of the resin composition was high, in the case of forming a magnetic layer with a film-like resin composition, the embedding property of the wiring pattern might be poor.

[0006] The present invention was devised in view of the above problems, and an object thereof is to provide a resin composition capable of obtaining a cured product having low thixotropy, excellent embedding property, and further high relative permeability.

Means for Solving the Problems

[0007] The present inventor earnestly studied to solve the above problems. As a result, the present inventor found that a resin composition containing a combination of an alloy magnetic powder having a BET specific surface area in a specific range, a magnetic powder having a BET specific surface area in another specific range, and a binder resin can solve the above problems, and completed the present invention. That is, the present invention includes the following.

[0008] 〔1〕 (A) An alloy magnetic powder having a BET specific surface area S A of 2 m 2 / g or more and 10 m 2 / g or less, (B) A magnetic powder having a BET specific surface area S B of 0.1 m 2 / g or more and less than 2 m 2 / g, and (C) A binder resin A resin composition containing. 〔2〕 The resin composition according to 〔1〕, wherein the volume ratio ((B) component / (A) component) of the (A) component and the (B) component is 0.9 or more and 20.0 or less. 〔3〕 The resin composition according to 〔1〕 or 〔2〕, wherein the total amount of the (A) component and the (B) component is 50% by volume or more based on 100% by volume of the non-volatile components in the resin composition. The resin composition according to any one of [1] to [3], wherein the component (A) contains an iron alloy-based powder containing Fe, Si, and Cr. The resin composition according to any one of [1] to [4], wherein the component (C) contains a thermosetting resin. The resin composition according to any one of [1] to [5], wherein the component (C) contains an epoxy resin. The resin composition according to [6], further comprising a component (D) epoxy curing accelerator. The resin composition according to any one of [1] to [7], wherein the amount of the component (C) is 60% by mass or more based on 100% by mass of the resin component in the resin composition. The resin composition according to any one of [1] to [8], which is in paste form at 23°C. The cured product of the resin composition according to any one of [1] to [9]. A resin sheet comprising a support and a resin composition layer formed of the resin composition according to any one of [1] to [9] on the support. A circuit board comprising the cured product of the resin composition according to any one of [1] to [9]. A circuit board comprising a substrate having through holes formed therein and the cured product of the resin composition according to any one of [1] to [9] filled in the through holes. An inductor substrate comprising the circuit board according to

[12] or

[13] .

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a resin composition capable of obtaining a cured product having low thixotropy, excellent embedability, and further high relative permeability.

Brief Description of the Drawings

[0010]

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[0011] Hereinafter, the present invention will be described in detail with reference to its preferred embodiments. However, the present invention is not limited to the following embodiments and examples, and can be arbitrarily modified and implemented without departing from the scope of the claims of the present invention and its equivalent scope.

[0012] In the following description, "permeability" represents "relative permeability" unless otherwise specified.

[0013] [1. Overview of Resin Composition] The resin composition according to an embodiment of the present invention contains, in combination, (A) an alloy magnetic powder having a BET specific surface area S A of 2 m 2 / g or more and 10 m 2 / g or less, (B) a magnetic powder having a BET specific surface area S B of 0.1 m 2 / g or more and less than 2 m 2 / g, and (C) a binder resin.

[0014] This resin composition can have low thixotropy and excellent embedability. Further, according to this resin composition, a cured product having a high relative permeability can be obtained. The inventor conjectures the mechanism by which such excellent effects are obtained as follows. However, the technical scope of the present invention is not limited by the following mechanism.

[0015] In the above resin composition, usually, the particle size of component (A) is small and the particle size of component (B) is large. Therefore, the particles of component (A) in the resin composition can enter the gaps formed between the particles of component (B). Thus, components (A) and (B) can be dispersed in the resin composition at a high density as a whole, so that the cured product obtained by curing the resin composition can have a high relative magnetic permeability.

[0016] Also, generally, since small particles have a large specific surface area, the friction on the surface of the particles increases, and thus the thixotropy tends to increase. For example, nanometer ferrite powder has a small particle size while having a tendency to have a large specific surface area. However, the component (A) formed of an alloy can have a specific surface area smaller than the particle size, so that the friction on the particle surface can be reduced. Therefore, the thixotropy of the resin composition can be lowered to obtain excellent embedability.

[0017] The resin composition may further contain an arbitrary component in combination with components (A), (B), and (C). However, it is preferable that the amount of any magnetic powder other than components (A) and (B) in the resin composition is small, and it is more preferable that no magnetic powder other than components (A) and (B) is contained. Specifically, the amount of any magnetic powder contained in the resin composition is preferably 0 mass% to 10 mass%, more preferably 0 mass% to 5 mass%, particularly preferably 0 mass% to 1 mass%, and ideally 0 mass%.

[0018] [2. (A) Alloy magnetic powder] The resin composition according to an embodiment of the present invention contains, as component (A), an (A) alloy magnetic powder having a BET specific surface area S within a specific range A . This (A) alloy magnetic powder may be a soft magnetic powder or a hard magnetic powder. Among them, from the viewpoint of significantly obtaining the effects of the present invention, the (A) alloy magnetic powder is preferably a soft magnetic powder.

[0019] (A) As the alloy magnetic powder, for example, crystalline or amorphous alloy powders such as Fe-Si-based alloy powder, Fe-Si-Al-based alloy powder, Fe-Cr-based alloy powder, Fe-Si-Cr-based alloy powder, Fe-Ni-Cr-based alloy powder, Fe-Cr-Al-based alloy powder, Fe-Ni-based alloy powder, Fe-Ni-Mo-based alloy powder, Fe-Ni-Mo-Cu-based alloy powder, Fe-Co-based alloy powder, Fe-Ni-Co-based alloy powder, Co-based amorphous alloy powder, etc. may be mentioned. Among them, as the (A) alloy magnetic powder, iron alloy-based powder is preferable. As the iron alloy-based powder, an iron alloy-based powder containing Fe and at least one element selected from the group consisting of Si, Cr, Al, Ni, and Co is preferable. Further, an iron alloy-based powder containing Fe and at least one element selected from the group consisting of Si, Cr, and Ni is preferable. In particular, the (A) alloy magnetic powder preferably contains at least one alloy-based powder selected from the group consisting of Fe-Si-Cr-based alloy powder and Fe-Ni-based alloy powder. The Fe-Si-Cr-based alloy powder represents an alloy powder containing Fe, Si, and Cr, and the Fe-Ni-based alloy powder represents an alloy powder containing Fe and Ni. (A) The alloy magnetic powder may contain only one kind of powder or may contain two or more kinds of powders.

[0020] (A) The BET specific surface area S of the alloy magnetic powder A is usually 2.0 m 2 / g or more, preferably 2.5 m 2 / g or more, more preferably greater than 2.5 m 2 / g, and even more preferably 2.6 m 2 / g or more, particularly preferably 3.0 m 2 / g or more, and preferably 10 m 2 / g or less, more preferably 9.5 m 2 / g or less, even more preferably 9 m 2 / g or less. When the (A) alloy magnetic powder has the BET specific surface area S within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made excellent. A

[0021] (A) The BET specific surface area S of the alloy magnetic powderA is preferably in a specific relationship with the BET specific surface area S of (B) magnetic powder. B Specifically, the ratio S of the BET specific surface area S of (A) alloy magnetic powder to the BET specific surface area S of (B) magnetic powder A is preferably 2.0 or more, more preferably 5.0 or more, particularly preferably 8.0 or more, and preferably 50 or less, more preferably 25 or less, particularly preferably 20 or less. When the ratio S B / S A / S B is within the above range, the relative permeability of the cured product, and the thixotropy and embedability of the resin composition can be made particularly excellent. A / S B Moreover, the difference S between the BET specific surface area S of (A) alloy magnetic powder

[0022] and the BET specific surface area S of (B) magnetic powder A is preferably 2.0 m B / g or more, more preferably 4.0 m A / g or more, particularly preferably 5.0 m B / g or more, and preferably 9.0 m 2 / g or less, more preferably 8.7 m 2 / g or less, particularly preferably 8.5 m 2 / g or less. When the difference S 2 / g or less. When the difference S 2 / g or less. When the difference S 2 / g or less. When the difference S A -S B is within the above range, the relative permeability of the cured product, and the thixotropy and embedability of the resin composition can be made particularly excellent.

[0023] Furthermore, the volume-based weighted average of the BET specific surface area S of (A) alloy magnetic powder A and the BET specific surface area S of (B) magnetic powder B is preferably within a specific range. Specifically, this volume-based weighted average is preferably 1.0 m 2 / g or more, more preferably 1.5 m 2 / g or more, particularly preferably 2.0 m 2 / g or more, and preferably 6.0 m 24.5 m / g or less, more preferably 4.5 m / g or less, particularly preferably 3.5 m / g or less. 2 The weighted average based on volume described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its volume ratio and the product of the BET specific surface area S of the magnetic powder (B) and its volume ratio. The volume ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by volume. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. 2 / g or less. The weighted average based on volume described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its volume ratio and the product of the BET specific surface area S of the magnetic powder (B) and its volume ratio. The volume ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by volume. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. A and its volume ratio, and the product of the BET specific surface area S of the magnetic powder and its volume ratio. B The weighted average based on volume described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its volume ratio and the product of the BET specific surface area S of the magnetic powder (B) and its volume ratio. The volume ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by volume. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent.

[0024] In addition, the weighted average based on mass of the BET specific surface area S of the alloy magnetic powder (A) and the BET specific surface area S of the magnetic powder (B) is preferably within a specific range. Specifically, this weighted average based on mass is preferably 1.0 m / g or more, more preferably 1.5 m / g or more, particularly preferably 2.0 m / g or more, and preferably 6.0 m / g or less, more preferably 4.5 m / g or less, particularly preferably 3.5 m / g or less. The weighted average based on mass described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its mass ratio and the product of the BET specific surface area S of the magnetic powder (B) and its mass ratio. The mass ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by mass. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. Usually, the BET specific surface area of the entire magnetic powder including the alloy magnetic powder (A), the magnetic powder (B), and any magnetic powder contained in the resin composition can fall within the range of the weighted average based on mass described above. A and the BET specific surface area S of the magnetic powder (B) B is preferably within a specific range. Specifically, this weighted average based on mass is preferably 1.0 m / g or more, more preferably 1.5 m / g or more, particularly preferably 2.0 m / g or more, and preferably 6.0 m / g or less, more preferably 4.5 m / g or less, particularly preferably 3.5 m / g or less. The weighted average based on mass described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its mass ratio and the product of the BET specific surface area S of the magnetic powder (B) and its mass ratio. The mass ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by mass. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. Usually, the BET specific surface area of the entire magnetic powder including the alloy magnetic powder (A), the magnetic powder (B), and any magnetic powder contained in the resin composition can fall within the range of the weighted average based on mass described above. 2 / g or more, more preferably 1.5 m / g or more, particularly preferably 2.0 m / g or more, and preferably 6.0 m / g or less, more preferably 4.5 m / g or less, particularly preferably 3.5 m / g or less. The weighted average based on mass described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its mass ratio and the product of the BET specific surface area S of the magnetic powder (B) and its mass ratio. The mass ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by mass. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. Usually, the BET specific surface area of the entire magnetic powder including the alloy magnetic powder (A), the magnetic powder (B), and any magnetic powder contained in the resin composition can fall within the range of the weighted average based on mass described above. 2 / g or more, particularly preferably 2.0 m / g or more, and preferably 6.0 m / g or less, more preferably 4.5 m / g or less, particularly preferably 3.5 m / g or less. The weighted average based on mass described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its mass ratio and the product of the BET specific surface area S of the magnetic powder (B) and its mass ratio. The mass ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by mass. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. Usually, the BET specific surface area of the entire magnetic powder including the alloy magnetic powder (A), the magnetic powder (B), and any magnetic powder contained in the resin composition can fall within the range of the weighted average based on mass described above. 2 / g or more, and preferably 6.0 m / g or less, more preferably 4.5 m / g or less, particularly preferably 3.5 m / g or less. The weighted average based on mass described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its mass ratio and the product of the BET specific surface area S of the magnetic powder (B) and its mass ratio. The mass ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by mass. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. Usually, the BET specific surface area of the entire magnetic powder including the alloy magnetic powder (A), the magnetic powder (B), and any magnetic powder contained in the resin composition can fall within the range of the weighted average based on mass described above. 2 / g or less, more preferably 4.5 m / g or less, particularly preferably 3.5 m / g or less. The weighted average based on mass described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its mass ratio and the product of the BET specific surface area S of the magnetic powder (B) and its mass ratio. The mass ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by mass. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. Usually, the BET specific surface area of the entire magnetic powder including the alloy magnetic powder (A), the magnetic powder (B), and any magnetic powder contained in the resin composition can fall within the range of the weighted average based on mass described above. 2 / g or less, particularly preferably 3.5 m / g or less. The weighted average based on mass described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its mass ratio and the product of the BET specific surface area S of the magnetic powder (B) and its mass ratio. The mass ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by mass. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. Usually, the BET specific surface area of the entire magnetic powder including the alloy magnetic powder (A), the magnetic powder (B), and any magnetic powder contained in the resin composition can fall within the range of the weighted average based on mass described above. 2 / g or less. The weighted average based on mass described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its mass ratio and the product of the BET specific surface area S of the magnetic powder (B) and its mass ratio. The mass ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by mass. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. Usually, the BET specific surface area of the entire magnetic powder including the alloy magnetic powder (A), the magnetic powder (B), and any magnetic powder contained in the resin composition can fall within the range of the weighted average based on mass described above. A and its mass ratio, and the product of the BET specific surface area S of the magnetic powder and its mass ratio. B The weighted average based on mass described above is the value obtained by summing the product of the BET specific surface area S of the alloy magnetic powder (A) and its mass ratio and the product of the BET specific surface area S of the magnetic powder (B) and its mass ratio. The mass ratio described above represents the ratio with the total of the alloy magnetic powder (A) and the magnetic powder (B) being 100% by mass. When the weighted average is within the above range, the relative permeability of the cured product and the thixotropy and embedability of the resin composition can be made particularly excellent. Usually, the BET specific surface area of the entire magnetic powder including the alloy magnetic powder (A), the magnetic powder (B), and any magnetic powder contained in the resin composition can fall within the range of the weighted average based on mass described above.

[0025] The BET specific surface area can be measured by the BET method. Specifically, the BET specific surface area can be measured by adsorbing nitrogen gas onto the sample surface using a specific surface area measuring device ("Macsorb HM Model 1210" manufactured by Mountech Co., Ltd.) in accordance with the BET method and using the BET multi-point method.

[0026] (A) The alloy magnetic powder preferably has substantially spherical particles or substantially ellipsoidal particles. The aspect ratio of the particles of the (A) alloy magnetic powder is preferably 2 or less, more preferably 1.5 or less, still more preferably 1.2 or less, and usually 1.0 or more. The said aspect ratio represents the ratio (Lb / La) of the major axis (Lb) and the minor axis (La).

[0027] (A) The average particle size of the alloy magnetic powder is preferably 0.8 μm or less, more preferably 0.6 μm or less, still more preferably 0.4 μm or less, still more preferably 0.3 μm or less, and particularly preferably 0.2 μm or less. The lower limit of the average particle size of the (A) alloy magnetic powder is not particularly limited, but may preferably be 0.01 μm or more, more preferably 0.05 μm or more, still more preferably 0.1 μm or more, and particularly preferably 0.12 μm or more.

[0028] Unless otherwise specified, the average particle size represents the volume-based median diameter. This average particle size can be measured by the laser diffraction / scattering method based on the Mie scattering theory. Specifically, it can be measured by creating a particle size distribution based on volume using a laser diffraction / scattering type particle size distribution measuring device and taking the median diameter thereof as the average particle size. As the measurement sample, a powder dispersed in water by ultrasonic waves can preferably be used. As the laser diffraction / scattering type particle size distribution measuring device, "LA-960" manufactured by Horiba, Ltd., "SALD-2200" manufactured by Shimadzu Corporation, etc. can be used.

[0029] (A) The true specific gravity of the alloy magnetic powder can be, for example, 6.5 g / cm 3 ~9.0 g / cm 3 or the like.

[0030] (A) The alloy magnetic powder may be a commercially available product. Specific examples of commercially available products of the (A) alloy magnetic powder include "G00129D", "G00212D", "G00220DC", etc. manufactured by JFE Minerals Co., Ltd. These may be used as they are, or two or more of them may be used in combination.

[0031] The amount (volume %) of the (A) alloy magnetic powder contained in the resin composition is preferably 1.0 volume % or more, more preferably 5.0 volume % or more, particularly preferably 10 volume % or more, and preferably 50 volume % or less, more preferably 40 volume % or less, particularly preferably 30 volume % or less, based on 100 volume % of the non-volatile components in the resin composition. When the amount of the (A) alloy magnetic powder is within the above range, the relative permeability of the cured product, as well as the thixotropy and embedability of the resin composition, can be made particularly excellent. The volume of each component contained in the resin composition can be obtained by dividing the mass by the true specific gravity.

[0032] The amount (mass %) of the (A) alloy magnetic powder contained in the resin composition is preferably 1.0 mass % or more, more preferably 5.0 mass % or more, particularly preferably 10 mass % or more, and preferably 70 mass % or less, more preferably 50 mass % or less, particularly preferably 40 mass % or less, based on 100 mass % of the non-volatile components in the resin composition. When the amount of the (A) alloy magnetic powder is within the above range, the relative permeability of the cured product, as well as the thixotropy and embedability of the resin composition, can be made particularly excellent.

[0033] (A) The amount of the alloy magnetic powder is preferably set so that the volume ratio of the (A) alloy magnetic powder to the (B) magnetic powder ((B) component / (A) component) falls within a specific range. Specifically, the volume ratio of the (A) alloy magnetic powder to the (B) magnetic powder ((B) component / (A) component) is preferably 0.9 or more, more preferably 1.0 or more, still more preferably 1.3 or more, particularly preferably 1.9 or more, and preferably 20.0 or less, more preferably 19.0 or less, still more preferably 15.0 or less, particularly preferably 10.0 or less. The volume of the components contained in the resin composition such as the (A) alloy magnetic powder and the (B) magnetic powder can be obtained by dividing the mass by the true specific gravity. The above volume ratio ((B) component / (A) component) can be obtained by dividing the volume of the (B) magnetic powder thus obtained by the volume of the (A) alloy magnetic powder. When the volume ratio ((B) component / (A) component) is within the above range, the relative permeability of the cured product, as well as the thixotropy and embedability of the resin composition, can be made particularly excellent.

[0034] (A) The amount of the alloy magnetic powder is preferably set so that the total amount of the (A) alloy magnetic powder and the (B) magnetic powder falls within a specific range. Specifically, the total amount (volume %) of the (A) alloy magnetic powder and the (B) magnetic powder is preferably 50 volume % or more, more preferably 55 volume % or more, particularly preferably 60 volume % or more, and preferably 80 volume % or less, more preferably 76 volume % or less, particularly preferably 73 volume % or less, based on 100 volume % of the non-volatile components in the resin composition. When the total amount of the (A) alloy magnetic powder and the (B) magnetic powder is within the above range, the relative permeability of the cured product, as well as the thixotropy and embedability of the resin composition, can be made particularly excellent.

[0035] Also, the total amount (mass %) of (A) alloy magnetic powder and (B) magnetic powder is preferably 80 mass % or more, more preferably 85 mass % or more, particularly preferably 90 mass % or more, and preferably 99 mass % or less, more preferably 96 mass % or less, particularly preferably 94 mass % or less, based on 100 mass % of the non-volatile components in the resin composition. When the total amount of (A) alloy magnetic powder and (B) magnetic powder is within the above range, the relative permeability of the cured product, and the thixotropy and embedability of the resin composition can be made particularly excellent.

[0036] The amount of (A) alloy magnetic powder is preferably set so that the mass ratio ((A) component / (C) component) of (A) alloy magnetic powder and (C) binder resin falls within a specific range. Specifically, the mass ratio ((A) component / (C) component) of (A) alloy magnetic powder and (C) binder resin is preferably 0.5 or more, more preferably 1.0 or more, particularly preferably 2.0 or more, and preferably 20 or less, more preferably 10 or less, particularly preferably 6.0 or less. When the mass ratio ((A) component / (C) component) of (A) alloy magnetic powder and (C) binder resin is within the above range, the relative permeability of the cured product, and the thixotropy and embedability of the resin composition can be made particularly excellent.

[0037] The amount of (A) alloy magnetic powder is preferably set so that the volume ratio ((A) component / (C) component) of (A) alloy magnetic powder and (C) binder resin falls within a specific range. Specifically, the volume ratio ((A) component / (C) component) of (A) alloy magnetic powder and (C) binder resin is preferably 0.05 or more, more preferably 0.10 or more, particularly preferably 0.40 or more, and preferably 1.5 or less, more preferably 1.0 or less, particularly preferably 0.80 or less. When the volume ratio ((A) component / (C) component) of (A) alloy magnetic powder and (C) binder resin is within the above range, the relative permeability of the cured product, and the thixotropy and embedability of the resin composition can be made particularly excellent.

[0038] [3. (B) Magnetic Powder] The resin composition according to one embodiment of the present invention has a BET specific surface area S within a specific range as the (B) component BIt contains (B) magnetic powder having []. The type of (B) magnetic powder is not particularly limited. The (B) magnetic powder may be a soft magnetic powder or a hard magnetic powder. Among them, from the viewpoint of significantly obtaining the effects of the present invention, it is preferable that the (B) magnetic powder is a soft magnetic powder. Examples of the (B) magnetic powder include magnetic metal oxide powder and magnetic metal powder.

[0039] Examples of the magnetic metal oxide powder include ferrite powders such as Fe-Mn-based ferrite powder, Mg-Zn-based ferrite powder, Mn-based ferrite powder, Mn-Zn-based ferrite powder, Mn-Mg-based ferrite powder, Cu-Zn-based ferrite powder, Mg-Sr-based ferrite powder, Mn-Mg-Sr-based ferrite powder, Ni-Zn-based ferrite powder, Ni-Zn-Cu-based ferrite powder, Ba-Zn-based ferrite powder, Ba-Mg-based ferrite powder, Ba-Ni-based ferrite powder, Ba-Co-based ferrite powder, Ba-Ni-Co-based ferrite powder, Y-based ferrite powder; iron oxide powders such as iron(III) oxide powder and magnetite powder; etc.

[0040] Examples of the magnetic metal powder include pure iron powder; crystalline or amorphous alloy magnetic powders such as Fe-Si-based alloy powder, Fe-Si-Al-based alloy powder, Fe-Cr-based alloy powder, Fe-Si-Cr-based alloy powder, Fe-Ni-Cr-based alloy powder, Fe-Cr-Al-based alloy powder, Fe-Ni-based alloy powder, Fe-Ni-Mo-based alloy powder, Fe-Ni-Mo-Cu-based alloy powder, Fe-Co-based alloy powder, Fe-Ni-Co-based alloy powder, Co-based amorphous alloy powder; etc.

[0041] (B) The magnetic powder preferably contains at least one magnetic powder selected from ferrite powder and alloy magnetic powder. (B) From the viewpoint of further improving the magnetic permeability, the magnetic powder preferably contains one or more kinds of alloy magnetic powder. As the alloy magnetic powder, iron alloy-based powder is preferable. As the iron alloy-based powder, an iron alloy-based powder containing Fe and at least one element selected from the group consisting of Si, Cr, Al, Ni, and Co is preferable. Further, an iron alloy-based powder containing Fe and at least one element selected from the group consisting of Si, Cr, and Ni is preferable. Among them, it is particularly preferable that (B) the magnetic powder contains at least one alloy magnetic powder selected from Fe-Si-Cr-based alloy powder and Fe-Ni-based alloy powder. (B) The magnetic powder may contain only one kind of powder or may contain two or more kinds of powders.

[0042] (B) The BET specific surface area S of the magnetic powder B is usually 0.1 m 2 / g or more, preferably 0.2 m 2 / g or more, more preferably 0.3 m 2 / g or more, and usually less than 2.0 m 2 / g, more preferably less than 1.5 m 2 / g or less, and still more preferably less than 1.0 m 2 / g or less. When the (B) magnetic powder has the BET specific surface area S within the above range, the relative magnetic permeability of the cured product, as well as the thixotropy and embeddability of the resin composition, can be made excellent. B

[0043] (B) The magnetic powder is preferably substantially spherical particles or substantially ellipsoidal particles. The aspect ratio of the particles of the (B) magnetic powder is preferably 4 or less, more preferably 3 or less, still more preferably 2 or less, and usually 1.0 or more.

[0044] (B) The average particle size of the magnetic powder is preferably 1.5 μm or more, more preferably 2.0 μm or more, still more preferably 2.5 μm or more, even more preferably 2.7 μm or more, particularly preferably 2.8 μm or more, and is preferably 50.0 μm or less, more preferably 40.0 μm or less, still more preferably 30.0 μm or less, particularly preferably 25.0 μm or less.

[0045] (B) The true specific gravity of the magnetic powder is, for example, 4.0 g / cm 3 ~10 g / cm 3 and may be such.

[0046] (B) Commercially available products may be used for the magnetic powder. Specific examples of commercially available products of the (B) magnetic powder include "AW02-08PF03", "KUAMET 6B2-53um", "KUAMET NC1-53um" manufactured by Epson Atmix Corporation; "Fe-50Ni" manufactured by DOWA Electronics Co., Ltd.; "MZ05S", "MZ10S", "M05S" manufactured by Powdertech Co., Ltd.; and the like. These may be used as they are alone, or two or more of them may be used in combination.

[0047] The amount (volume %) of the (B) magnetic powder contained in the resin composition is preferably 10 volume % or more, more preferably 20 volume % or more, particularly preferably 30 volume % or more, and is preferably 80 volume % or less, more preferably 70 volume % or less, particularly preferably 60 volume % or less, based on 100 volume % of the non-volatile components in the resin composition. When the amount of the (B) magnetic powder is within the above range, the relative permeability of the cured product, as well as the thixotropy and embedability of the resin composition, can be made particularly excellent.

[0048] The amount (mass %) of the (B) magnetic powder contained in the resin composition is preferably 20 mass % or more, more preferably 30 mass % or more, particularly preferably 50 mass % or more, and is preferably 90 mass % or less, more preferably 80 mass % or less, particularly preferably 70 mass % or less, based on 100 mass % of the non-volatile components in the resin composition. When the amount of the (B) magnetic powder is within the above range, the relative permeability of the cured product, as well as the thixotropy and embedability of the resin composition, can be made particularly excellent.

[0049] [4. (C) Binder Resin] The resin composition according to an embodiment of the present invention contains a (C) binder resin as the component (C). As the binder resin, for example, a thermosetting resin, a thermoplastic resin, etc. can be used. Examples of the thermosetting resin include an epoxy resin, a phenolic resin, a naphthol resin, a benzoxazine resin, an active ester resin, a cyanate ester resin, a carbodiimide resin, an amine resin, an acid anhydride resin, etc. Examples of the thermoplastic resin include a phenoxy resin, an acrylic resin, a polyvinyl acetal resin, a butyral resin, a polyimide resin, a polyamideimide resin, a polyethersulfone resin, and a polysulfone resin, etc. The (B) binder resin may be used alone or in combination of two or more. Therefore, for example, as the (C) binder resin, a thermosetting resin and a thermoplastic resin may be used in combination. Among them, it is preferable to use a thermosetting resin as the (B) binder resin.

[0050] As the thermosetting resin, an epoxy resin is preferable. The epoxy resin means a resin having an epoxy group. When the (C) binder resin contains an epoxy resin, the specific magnetic permeability of the cured product, as well as the thixotropy and embedding property of the resin composition can be made particularly excellent.

[0051] Examples of the epoxy resin include, for example, bixylenol type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, tris-phenol type epoxy resin, naphthol novolak type epoxy resin, phenol novolak type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, naphthylene ether type epoxy resin, trimethylol type epoxy resin, tetraphenylethane type epoxy resin, glycidyl ether type aliphatic epoxy resin, glycidyl ether type aromatic epoxy resin, and the like. The epoxy resin may be used alone or in combination of two or more.

[0052] The resin composition preferably contains, as the epoxy resin, an epoxy resin having two or more epoxy groups in one molecule. From the viewpoint of significantly obtaining the desired effects of the present invention, the proportion of the epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more with respect to 100% by mass of the nonvolatile component of the epoxy resin.

[0053] The epoxy resin preferably has an aromatic structure. When two or more epoxy resins are used, it is preferable that one or more epoxy resins have an aromatic structure. The aromatic structure is a chemical structure generally defined as an aromatic group, and includes polycyclic aromatics and aromatic heterocycles.

[0054] Epoxy resins include liquid epoxy resins (hereinafter sometimes referred to as "liquid epoxy resins") that are liquid at a temperature of 25°C and solid epoxy resins (hereinafter sometimes referred to as "solid epoxy resins") that are solid at a temperature of 25°C. The resin composition may contain only a liquid epoxy resin as the epoxy resin, or may contain a combination of a liquid epoxy resin and a solid epoxy resin in addition to the liquid epoxy resin. However, in a preferred embodiment, it contains only a liquid epoxy resin.

[0055] The amount of the liquid epoxy resin is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 100% by mass, based on 100% by mass of the total epoxy resin.

[0056] As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferred.

[0057] Examples of the liquid epoxy resin include glycidol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ether type aliphatic epoxy resins, glycidyl ether type aromatic epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexanedimethanol type epoxy resins, dicyclopentadiene type epoxy resins, and epoxy resins having a butadiene structure. Among them, bisphenol A type epoxy resins, bisphenol F type epoxy resins, glycidyl ether type aliphatic epoxy resins, and glycidyl ether type aromatic epoxy resins are more preferred.

[0058] Specific examples of the liquid epoxy resin include "HP4032", "HP4032D", "HP4032SS" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "828US", "jER828EL" (bisphenol A-type epoxy resin), "jER807" (bisphenol F-type epoxy resin), "jER152" (phenol novolak-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD" (glycidyl ether-type aromatic epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (glycerol-type epoxy resin (Adeka glycerol)), "EP-3980S" (glycidylamine-type epoxy resin), "EP-4088S" (glycidyl ether-type aliphatic epoxy resin) manufactured by ADEKA Corporation; "ZX-1059" (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester-type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celoxide 2021P" (alicyclic epoxy resin having an ester skeleton), "PB-3600" (epoxy resin having a butadiene structure) manufactured by Daicel Corporation; "ZX1658", "ZX1658GS" (liquid 1,4-glycidylcyclohexane) manufactured by Nippon Steel Chemical & Material Co., Ltd., etc.

[0059] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferred.

[0060] As the solid epoxy resin, a bicyclol type epoxy resin, a naphthalene type epoxy resin, a naphthalene type tetrafunctional epoxy resin, a naphthol novolak type epoxy resin, a cresol novolak 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, a phenol aralkyl type epoxy resin, a tetraphenylethane type epoxy resin, a phenolphthalimide type epoxy resin, a phenolphthalein type epoxy resin are preferable.

[0061] Specific examples of the solid epoxy resin include "HP4032H" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resin) manufactured by DIC Corporation; "N-690" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "HP-7200", "HP-7200HH", "HP-7200H", and "HP-7200L" (dicyclopentadiene-type epoxy resin) manufactured by DIC Corporation; "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", and "HP6000" (naphthylene ether-type epoxy resin) manufactured by DIC Corporation; "EPPN-502H" (trisphenol-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolak-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", and "NC3100" (biphenyl-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V" (naphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN485" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN375" (dihydroxynaphthalene-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YX4000HK", and "YL7890" (bixylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX7700" (phenol aralkyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100" and "CG-500" manufactured by Osaka Gas Chemical Co., Ltd.; "YL7760" (bisphenol AF-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1010" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "jER1031S" (tetraphenylethane-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "WHR991S" (phenolphthalimide-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd., and the like. These may be used alone or in combination of two or more types.

[0062] When using a solid epoxy resin and a liquid epoxy resin in combination as the epoxy resin, the mass ratio of the solid epoxy resin to the liquid epoxy resin (solid epoxy resin / liquid epoxy resin) is not particularly limited, but is preferably 1 or less, more preferably 0.5 or less, still more preferably 0.1 or less, even more preferably 0.05 or less, and particularly preferably 0.01 or less.

[0063] The epoxy equivalent of the epoxy resin is preferably 50 g / eq. to 5000 g / eq., more preferably 50 g / eq. to 3000 g / eq., still 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 the resin per equivalent of epoxy groups. This epoxy equivalent can be measured according to JIS K7236.

[0064] From the viewpoint of significantly obtaining the desired effects of the present invention, the weight average molecular weight (Mw) of the epoxy resin is preferably 100 to 5000, more preferably 250 to 3000, and still more preferably 400 to 1500. The weight average molecular weight of the resin can be measured as a value in terms of polystyrene by gel permeation chromatography (GPC) method.

[0065] The amount (volume %) of the epoxy resin is preferably 10 volume % or more, more preferably 15 volume % or more, and particularly preferably 20 volume % or more, and preferably 80 volume % or less, more preferably 60 volume % or less, and particularly preferably 40 volume % or less with respect to 100 volume % of the non-volatile components in the resin composition. When the amount of the epoxy resin is within the above range, the relative permeability of the cured product, and the thixotropy and embedability of the resin composition can be made particularly excellent.

[0066] The amount of the epoxy resin (mass %) is preferably 0.1 mass % or more, more preferably 1.0 mass % or more, particularly preferably 3.0 mass % or more, and preferably 50 mass % or less, more preferably 30 mass % or less, still more preferably 20 mass % or less, based on 100 mass % of the non-volatile components in the resin composition. When the amount of the epoxy resin is within the above range, the relative permeability of the cured product, and the thixotropy and embedability of the resin composition can be made particularly excellent.

[0067] (C) When the binder resin contains an epoxy resin, the (C) binder resin may further contain an epoxy curing agent. The epoxy curing agent represents any thermosetting resin that can react with the epoxy resin to cure the resin composition. Examples of the epoxy curing agent include phenolic curing agents, carbodiimide curing agents, acid anhydride curing agents, amine curing agents, benzoxazine curing agents, cyanate ester curing agents, thiol curing agents, and the like. The epoxy curing agent may be used alone or in combination of two or more.

[0068] The phenolic curing agent is not particularly limited, but biphenyl type curing agents, naphthalene type curing agents, phenol novolak type curing agents, naphthylene ether type curing agents, and phenolic curing agents containing a triazine skeleton are preferred. Specific examples include "MEH-7700", "MEH-7810", "MEH-7851" (manufactured by Meiwa Kasei Co., Ltd.) of biphenyl type curing agents, "NHN", "CBN", "GPH" (manufactured by Nippon Kayaku Co., Ltd.), "SN170", "SN180", "SN190", "SN475", "SN485", "SN495", "SN375", "SN395" (manufactured by Nippon Steel Chemical Co., Ltd.), "EXB9500" (manufactured by DIC Corporation) of naphthalene type curing agents, "TD2090" (manufactured by DIC Corporation) of phenol novolak type curing agents, "EXB-6000" (manufactured by DIC Corporation) of naphthylene ether type curing agents, and the like. Specific examples of the phenolic curing agent containing a triazine skeleton include "LA3018", "LA7052", "LA7054", "LA1356" (manufactured by DIC Corporation), and the like. In particular, naphthalene type curing agents and phenolic curing agents containing a triazine skeleton are more suitable.

[0069] Examples of the carbodiimide-based curing agent include curing agents having one or more, preferably two or more carbodiimide structures in one molecule. For example, aliphatic biscarbodiimides such as tetramethylene-bis(t-butylcarbodiimide) and cyclohexane bis(methylene-t-butylcarbodiimide); biscarbodiimides such as aromatic biscarbodiimides such as phenylene-bis(xilylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylene carbodiimide, polytrimethylhexamethylene carbodiimide, polycyclohexylene carbodiimide, poly(methylenebiscyclohexylene carbodiimide), and poly(isophorone carbodiimide); aromatic polycarbodiimides such as poly(phenylene carbodiimide), poly(naphthylene carbodiimide), poly(tolylene carbodiimide), poly(methyldiisopropylphenylene carbodiimide), poly(triethylphenylene carbodiimide), poly(diethylphenylene carbodiimide), poly(triisopropylphenylene carbodiimide), poly(diisopropylphenylene carbodiimide), poly(xylylene carbodiimide), poly(tetramethylxylylene carbodiimide), poly(methylenediphenylene carbodiimide), and poly[methylenebis(methylphenylene) carbodiimide]. Examples of commercially available carbodiimide-based curing agents include "Carbodilite V-02B", "Carbodilite V-03", "Carbodilite V-04K", "Carbodilite V-07", and "Carbodilite V-09" manufactured by Nisshinbo Chemical Inc.; "Stabaxol P", "Stabaxol P400", "Highcadil 510", etc. manufactured by Rhein Chemie

[0070] Examples of the acid anhydride-based curing agent include curing agents having one or more acid anhydride groups in one molecule, and curing agents having two or more acid anhydride groups in one molecule are preferred. Specific examples of the acid anhydride-based curing agent 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, benzophenone tetracarboxylic dianhydride, 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 polymer-type acid anhydrides such as styrene-maleic acid resin copolymerized from styrene and maleic acid. Commercially available products of the acid anhydride-based curing agent include, for example, "HNA-100", "MH-700", "MTA-15", "DDSA", "OSA" manufactured by Shin Nippon Rika Co., Ltd., "YH-306", "YH-307" manufactured by Mitsubishi Chemical Corporation, and "HN-2200", "HN-5500" manufactured by Hitachi Chemical Co., Ltd.

[0071] Examples of amine-based curing agents include curing agents having one or more, preferably two or more amino groups in one molecule, such as aliphatic amines, polyether amines, alicyclic amines, aromatic amines, etc. Among them, aromatic amines are preferred. The amine-based curing agent is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of the amine-based curing agent include 4,4'-methylenebis(2,6-dimethylaniline), 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-hydroxyphenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, etc. The amine-based curing agent may be a commercially available product, such as "SEIKACURE-S" manufactured by Seika Corporation, "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD A-A", "KAYAHARD A-B", "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd., "EPICURE W" manufactured by Mitsubishi Chemical Corporation, etc.

[0072] Specific examples of the benzoxazine-based curing agent include "JBZ-OP100D", "ODA-BOZ" manufactured by JFE Chemical Corporation; "HFB2006M" manufactured by Showa Highpolymer Co., Ltd.; "P-d", "F-a", etc. manufactured by Shikoku Kasei Kogyo Co., Ltd.

[0073] Examples of cyanate ester curing agents 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'-ethylidenediphenyl 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 and cresol novolac; prepolymers in which part of these cyanate resins is triazine-ized, and the like. Specific examples of cyanate ester curing agents include "PT30" and "PT60" (both phenol novolac type polyfunctional cyanate ester resins), "BA230", "BA230S75" (a prepolymer in which part or all of bisphenol A dicyanate is triazine-ized to form a trimer), etc. manufactured by Lonza Japan Co., Ltd.

[0074] Examples of thiol curing agents include trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), tris(3-mercaptopropyl) isocyanurate, and the like.

[0075] The reaction group equivalent of the epoxy curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., still more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The reaction group equivalent represents the mass of the epoxy curing agent per equivalent of the reaction group.

[0076] The amount of the epoxy curing agent is preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less, and particularly preferably 10% by mass or less, based on 100% by mass of the non-volatile components in the resin composition. The lower limit can be, for example, 0% by mass or more, 0.01% by mass or more, 0.1% by mass or more, etc.

[0077] (C) The amount (volume %) of the binder resin is preferably 10% by volume or more, more preferably 15% by volume or more, and particularly preferably 20% by volume or more, based on 100% by volume of the non-volatile components in the resin composition, and is preferably 80% by volume or less, more preferably 60% by volume or less, and particularly preferably 40% by volume or less. When the amount of the (C) binder resin is within the above range, the relative magnetic permeability of the cured product, and the thixotropy and embedability of the resin composition can be made particularly excellent.

[0078] (C) The amount (mass %) of the binder resin is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, still more preferably 3.0% by mass or more, and particularly preferably 5.0% by mass or more, based on 100% by mass of the non-volatile components in the resin composition, and is preferably 50% by mass or less, more preferably 30% by mass or less, and still more preferably 20% by mass or less. When the amount of the (C) binder resin is within the above range, the relative magnetic permeability of the cured product, and the thixotropy and embedability of the resin composition can be made particularly excellent.

[0079] (C) The amount of the binder resin is preferably 60% by mass or more, more preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on 100% by mass of the resin components in the resin composition, and is preferably 100% by mass or less, more preferably 95% by mass or less, and particularly preferably 90% by mass or less. When the amount of the (C) binder resin is within the above range, the relative magnetic permeability of the cured product, and the thixotropy and embedability of the resin composition can be made particularly excellent. The resin components of the resin composition refer to the components other than the inorganic fillers such as the (A) component and the (B) component among the non-volatile components in the resin composition.

[0080] [5. (D) Epoxy Curing Accelerator] When the binder resin contains an epoxy resin, the resin composition according to an embodiment of the present invention may further contain (D) an epoxy curing accelerator as an optional component. The (D) epoxy curing accelerator has a function of accelerating the curing of the epoxy resin.

[0081] Examples of the (D) epoxy curing accelerator include imidazole-based curing accelerators, phosphorus-based curing accelerators, urea-based curing accelerators, guanidine-based curing accelerators, metal-based curing accelerators, amine-based curing accelerators, and the like. Among them, the (D) epoxy curing accelerator preferably contains an imidazole-based curing accelerator. The (D) epoxy curing accelerator may be used alone or in combination of two or more.

[0082] Examples of imidazole-based curing accelerators include imidazole compounds such as 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-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, and adducts of imidazole compounds and epoxy resins. As the imidazole-based curing accelerator, commercially available products may be used. For example, "1B2PZ", "2MZA-PW", "2PHZ-PW" manufactured by Shikoku Kasei Kogyo Co., Ltd., "P200-H50" manufactured by Mitsubishi Chemical Corporation, etc. can be mentioned.

[0083] Examples of phosphorus-based curing accelerators include aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium) pyromellitate, tetrabutylphosphonium hydrogen hexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, di-tert-butylmethylphosphonium tetraphenylborate; aromatic phosphonium salts such as methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, 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, butyltriphenylphosphonium thiocyanate; aromatic phosphine-borane complexes such as triphenylphosphine·triphenylborane; aromatic phosphine-quinone addition reactants such as triphenylphosphine·p-benzoquinone addition reactant; aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, tricyclohexylphosphine;Examples include aromatic phosphines such as 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, 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-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, 2,2'-bis(diphenylphosphino)diphenylether, etc.;

[0084] Examples of the urea-based curing accelerators include aliphatic dimethylureas such as 1,1-dimethylurea; 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, 3-cyclooctyl-1,1-dimethylurea; and aromatic dimethylureas such as 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, 3-(3,4-dimethylphenyl)-1,1-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), N,N-(4-methyl-1,3-phenylene)bis(N’,N’-dimethylurea) [toluene bisdimethylurea].

[0085] Examples of the 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, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, 1-(o-tolyl)biguanide.

[0086] Examples of the metal-based hardening accelerator include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of the organometallic complex include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organonickel complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of the organometallic salt include zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0087] Examples of the amine-based hardening accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)undecene. As the amine-based hardening accelerator, commercially available products may be used, and examples thereof include "MY-25" manufactured by Ajinomoto Fine-Techno Co., Inc.

[0088] (D) The amount (volume %) of the epoxy hardening accelerator is preferably 20 volume % or less, more preferably 10 volume % or less, and particularly preferably 5 volume % or less with respect to 100 volume % of the nonvolatile components in the resin composition. The lower limit may be, for example, 0 volume % or more, 0.01 volume % or more, 0.1 volume % or more, 0.5 volume % or more, etc.

[0089] (D) The amount (mass %) of the epoxy hardening accelerator is preferably 10 mass % or less, more preferably 5 mass % or less, and particularly preferably 2 mass % or less with respect to 100 mass % of the nonvolatile components in the resin composition. The lower limit may be, for example, 0 mass % or more, 0.01 mass % or more, 0.1 mass % or more, 0.5 mass % or more, etc.

[0090] [6.(E) Optional Component] The resin composition according to an embodiment of the present invention may further contain (E) an optional component in combination with the above-described components. Examples of the optional component 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; organic fillers such as rubber particles; organometallic compounds such as organic copper compounds and organic zinc 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 benton and montmorillonite; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as urea silane; adhesion imparting agents such as triazole-based adhesion imparting agents, tetrazole-based adhesion imparting agents, and triazine-based adhesion imparting agents; antioxidants such as hindered phenol-based antioxidants and hindered amine-based antioxidants; fluorescent brighteners such as stilbene derivatives; surfactants such as fluorine-based surfactants and silicone-based surfactants; flame retardants such as phosphorus-based flame retardants (e.g., phosphate ester compounds, phosphazene compounds, phosphinic acid compounds, red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic-based flame retardants (e.g., antimony trioxide); dispersants such as phosphate ester-based dispersants, polyoxyalkylene-based dispersants, acetylene-based dispersants, silicone-based dispersants, anionic dispersants, and cationic dispersants; 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; and the like. The (E) optional component may be used alone or in combination of two or more.

[0091] [7. (F) Organic Solvent] The resin composition according to an embodiment of the present invention may further contain an optional (F) organic solvent as a volatile component in addition to the non-volatile components such as the above-described components (A), (B), (C), (D), and (E).

[0092] As the (F) organic solvent, those capable of dissolving the resin component contained in the non-volatile component are preferred. Examples of the (F) organic solvent include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isoamyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; ether solvents such as tetrahydropyran, tetrahydrofuran, 1,4-dioxane, diethyl ether, diisopropyl ether, dibutyl ether, and diphenyl ether; alcohol solvents such as methanol, ethanol, propanol, butanol, and ethylene glycol; ether ester solvents such as 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diglycol acetate, γ-butyrolactone, and methyl methoxypropionate; ester alcohol solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. The (F) organic solvent may be used alone or in combination of two or more in any ratio.

[0093] (F) The amount of the organic solvent is preferably small. For example, with respect to 100% by mass of the non-volatile components in the resin composition, the amount of the (F) organic solvent can be 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. Among them, it is preferable that the resin composition does not contain an organic solvent. That is, the amount of the (F) organic solvent is preferably 0% by mass.

[0094] [8. Characteristics of the resin composition] The resin composition according to one embodiment of the present invention can have low thixotropy. The thixotropy of the resin composition can usually be represented by the thixotropy index (T.I.). The specific range of the thixotropy index of the resin composition is preferably 2.7 or less, more preferably 2.2 or less, still more preferably 2.0 or less, and particularly preferably 1.8 or less. There is no particular limitation on the lower limit of the thixotropy index. However, from the viewpoint of forming a thick layer when forming a layer of the resin composition, the lower limit of the thixotropy index of the resin composition can be, for example, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, etc.

[0095] The thixotropy index T.I. of the resin composition is the viscosity η at a rotor rotation speed of 0.5 rpm and 5 rpm measured using an E-type viscometer at 25 °C ± 0.1 °C 0.5 and the viscosity η5, and can be calculated by the following formula (M1). T.I. = η 0.5 / η5 (M1) As the E-type viscometer, for example, "RE-80U" manufactured by Toki Sangyo Co., Ltd. (3° × R9.7 cone rotor, measurement sample 0.22 ml) can be used. As the specific measurement method of the thixotropy index, the method described in the examples below can be adopted.

[0096] The resin composition according to an embodiment of the present invention can have excellent embedability. This embedability can be evaluated as the property of being able to well fill the through-holes formed in the substrate. For example, through-holes with a diameter of 500 μm are formed in an FR4 substrate with a thickness of 1 mm. An evaluation test is conducted in which the resin composition is printed on the substrate at a printing speed of 150 mm / s using a urethane squeegee in a vacuum of 25°C and 0.1 Pa in these through-holes. When this evaluation test is conducted, the above-described resin composition usually does not stop in the middle of the through-holes and can be filled throughout the through-holes. Therefore, when the resin composition is printed on one side (front side) of the substrate, the resin composition can be discharged from the openings of the through-holes on the other side (back side) of the substrate. The above evaluation test can be specifically implemented by the method described in the examples below.

[0097] Also, the resin composition according to an embodiment of the present invention can usually exhibit excellent embedability even when a resin composition layer is formed. For example, a resin sheet provided with a resin composition layer formed of the resin composition is prepared. Then, this resin sheet is bonded to a substrate having a wiring pattern formed on its surface. In this case, the wiring pattern formed on the surface of the substrate can be well embedded in the resin composition layer. Therefore, usually, it is possible to suppress the formation of voids between the resin composition layer and the wiring pattern.

[0098] The cured product obtained by curing the resin composition according to an embodiment of the present invention can have excellent magnetic properties. Therefore, the cured product of the resin composition can usually have a high relative permeability. The specific relative permeability of the cured product of the resin composition is preferably 7.5 or more, more preferably 8.0 or more, still more preferably 9.0 or more, and particularly preferably 10.0 or more. The upper limit of the relative permeability is not particularly limited, but can be, for example, 30.0 or less, 20.0 or less, 15.0 or less, etc.

[0099] The above relative permeability can be measured under the conditions of a measurement frequency of 100 MHz and a measurement temperature of 23°C for a cured product obtained by heating and curing the resin composition at 180°C for 90 minutes. As a specific method for measuring the relative permeability, the method described in the examples below can be adopted.

[0100] [9. Method for manufacturing resin composition] The resin composition according to one embodiment of the present invention can be manufactured, for example, by mixing the above-described respective components. There is no limitation on the order of mixing. Also, the mixing of some or all of the components may be performed simultaneously. During the process of mixing the respective components, the temperature may be appropriately set. For example, heating and / or cooling may be performed temporarily or throughout the process. Further, stirring or shaking may be performed during the process of mixing the respective components. Furthermore, defoaming may be performed under low-pressure conditions such as under vacuum during the process of mixing the respective components or after mixing.

[0101] [10. Use of resin composition] The resin composition according to one embodiment of the present invention may be used, for example, in the form of a paste-like resin composition at room temperature of 23°C. Also, the resin composition layer may be used, for example, in the form of a resin sheet including the layer of the resin composition.

[0102] The resin composition may be, for example, a paste-like resin composition using an organic solvent, or may be a paste-like resin composition not containing an organic solvent by using a liquid resin component such as a liquid binder resin. When the content of the organic solvent in the resin composition is small or the resin composition does not contain an organic solvent, generation of voids due to volatilization of the organic solvent can be suppressed, and a resin composition excellent in handleability and workability can be obtained.

[0103] The resin composition can be suitably used, for example, as a resin composition for filling through-holes. Also, the resin composition can be suitably used, for example, as a resin composition for forming an inductor element for manufacturing an inductor element.

[0104] [11. Resin sheet] The resin sheet includes a support and a resin composition layer formed of the above resin composition on the support.

[0105] 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 is not particularly limited, and may be, for example, 5 μm or more, 10 μm or more, etc.

[0106] Examples of the support include a film of a plastic material, a metal foil, and a release paper, and a film of a plastic material and a metal foil are preferred.

[0107] When using a film of a plastic material 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), polyethersulfide (PES), polyether ketone, polyimide, etc. Among them, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0108] When using a metal foil as the support, examples of the metal foil include a copper foil and an aluminum foil, and a copper foil is preferred. As the copper foil, a foil made of single metal copper may be used, or a foil made of an alloy of copper and other metals (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0109] The support may be subjected to a mat treatment or a corona treatment on the surface that joins the resin composition layer.

[0110] In addition, as the support, a support with a release layer having a release layer on the surface that bonds to the resin composition layer may be used. Examples of the release agent used for 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. As the support with a release layer, a commercially available product may be used. For example, "PET501010", "SK-1", "AL-5", "AL-7" manufactured by Lintec Corporation, which are PET films having a release layer mainly composed of a silicone-based release agent or an alkyd resin-based release agent; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; "Unipile" manufactured by Unitika Ltd., etc.

[0111] The thickness of the support is not particularly limited, but a range of 5 μm to 75 μm is preferable, and a range of 10 μm to 60 μm is more preferable. When using a support with a release layer, it is preferable that the total thickness of the support with a release layer is within the above range.

[0112] In the resin sheet, a protective film conforming to the support can be further laminated on the surface of the resin composition layer that is not bonded to the support (that is, 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 laminating the protective film, it is possible to suppress the adhesion of dust and scratches to the surface of the resin composition layer. The resin sheet can be stored in a rolled state.

[0113] The resin sheet can be manufactured, for example, by applying a resin composition onto a support using a coating device such as a die coater to form a resin composition layer. If necessary, an organic solvent may be mixed with the resin composition and then applied onto the support. When using an organic solvent, drying may be performed after application if necessary.

[0114] Drying may be carried out by methods such as heating and hot air blowing. The drying conditions are not particularly limited, but the drying is carried out so that the content of the organic solvent in the resin composition layer is usually 10% by mass or less, preferably 5% by mass or less. Although it varies depending on the components contained in the resin composition, for example, the resin composition layer can be formed by drying at 50°C to 150°C for 3 minutes to 10 minutes.

[0115] The resin sheet can be stored by winding it into a roll. When the resin sheet has a protective film, it can usually be used by peeling off the protective film.

[0116] [12. Circuit board] The circuit board according to an embodiment of the present invention 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. The circuit board according to the first example includes a substrate in which holes are formed and a cured product of the resin composition filled in the holes. Further, the circuit board according to the second example includes a cured product layer formed of a cured product of the resin composition. Hereinafter, the circuit boards according to these first and second examples will be described.

[0117] [12.1. Circuit board according to the first example] The circuit board according to the first example includes a substrate in which holes are formed and a cured product of the resin composition filled in the holes. This circuit board is, for example, (1) A step of filling the holes of the substrate with the resin composition, (2) A step of curing the resin composition to obtain a cured product, can be manufactured by a manufacturing method including. Further, the manufacturing method of the circuit board according to the first example further includes (3) A step of polishing the surface of the cured product or the resin composition, (4) A step of roughening the cured product, and (5) A step of forming a conductor layer on the surface of the cured product that has been roughened. It may be included. Usually, the above steps (1) to (5) are performed in the order of steps (1) to (5), but step (2) may be performed after step (3). In the method for manufacturing 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 description, an example using a substrate in which through-holes as holes penetrating the substrate in the thickness direction are formed will be shown and described.

[0118] <Step (1)> Step (1) usually includes a step of preparing a substrate in which through-holes are formed. The substrate may be prepared by purchasing it from the market. Also, the substrate may be prepared by manufacturing it using an appropriate material. Hereinafter, a method for manufacturing a substrate according to an example will be described.

[0119] FIG. 1 is a cross-sectional view schematically showing a core substrate 10 prepared in the method for manufacturing a circuit board according to the first example of an embodiment of the present invention. The step of preparing the substrate may include a step of preparing the core substrate 10 as in the example shown in FIG. 1. The core substrate 10 usually includes a support substrate 11. Examples of the support substrate 11 include insulating base materials such as glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. Also, a metal layer may be provided on the support substrate 11. The metal layer may be provided on one side of the support substrate 11 or on both sides. Here, an example in which a first metal layer 12 and a second metal layer 13 are provided on both surfaces of the support substrate 11 is shown. Examples of the first metal layer 12 and the second metal layer 13 include layers formed of a metal such as copper. The first metal layer 12 and the second metal layer 13 may be, for example, copper foils such as carrier-added copper foils, or metal layers formed of the material of the conductor layer described later.

[0120] FIG. 2 is a cross-sectional view schematically showing a core substrate 10 in which a through hole 14 is formed in a method for manufacturing a circuit board according to a first example of an embodiment of the present invention. The step of preparing the substrate may include a step of forming a through hole 14 in the core substrate 10 as in the example shown in FIG. 2. The through hole 14 can be formed by a method such as drilling, laser irradiation, plasma irradiation, etc. Usually, the through hole 14 can be formed by forming a through hole in the core substrate 10. For a specific example, the formation of the through hole 14 can be carried out using a commercially available drilling device. Examples of commercially available drilling devices include, for example, "ND-1S211" manufactured by Hitachi Via Mechanics, Ltd.

[0121] FIG. 3 is a cross-sectional view schematically showing a core substrate 10 in which a plating layer 20 is formed in a through hole 14 in a method for manufacturing a circuit board according to a first example of an embodiment of the present invention. The step of preparing the substrate may include a step of forming a plating layer 20 as shown in FIG. 3 after performing a roughening treatment on the core substrate 10 as necessary. As the above-mentioned roughening treatment, either dry or wet roughening treatment may be performed. Examples of dry roughening treatment include plasma treatment, etc. Also, examples of wet roughening treatment include a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing liquid performed in this order. The plating layer 20 can be formed by a plating method. The procedure for forming the plating layer 20 by the plating method may be the same as that for forming the conductor layer in step (5) described later. Here, an example in which the plating layer 20 is formed in the through hole 14, on the surface of the first metal layer 12, and on the surface of the second metal layer 13 will be described.

[0122] FIG. 4 is a cross-sectional view schematically showing a state in which a resin composition 30a is filled in a through hole of a core substrate 10 in a method for manufacturing a circuit board according to a first example of an embodiment of the present invention. Step (1) includes preparing the core substrate 10 having the through holes 14 formed as described above, and then filling the through holes 14 of the core substrate 10 with the resin composition 30a as shown in FIG. 4. The filling can be performed, for example, by a printing method. Examples of the printing method include a method of printing the resin composition 30a into the through holes 14 via a squeegee, a method of printing the resin composition 30a via a cartridge, a method of mask printing to print the resin composition 30a, a roll coating method, an inkjet method, and the like. Usually, the excess resin composition 30a protrudes or adheres outside the through holes 14a. Therefore, the resin composition 30a can be provided not only inside the through holes 14a but also outside the through holes 14a.

[0123] <Step (2)> FIG. 5 is a schematic cross-sectional view for explaining step (2) of a method for manufacturing a circuit board according to a first example of an embodiment of the present invention. Step (2) includes curing the resin composition 30a to form a cured product 30 as shown in FIG. 5 after filling the through holes 14 with the resin composition 30a.

[0124] The curing of the resin composition 30a is usually performed by heat curing. The heat curing conditions of 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, still more preferably 150°C or higher, and preferably 245°C or lower, more preferably 220°C or lower, still more preferably 200°C or lower. The curing time is preferably 5 minutes or longer, more preferably 10 minutes or longer, still more preferably 15 minutes or longer, and preferably 120 minutes or shorter, more preferably 110 minutes or shorter, still more preferably 100 minutes or shorter.

[0125] The degree of curing of the cured product 30 obtained in step (2) is preferably 80% or higher, more preferably 85% or higher, still more preferably 90% or higher. The degree of curing can be measured, for example, using a differential scanning calorimeter.

[0126] The method for manufacturing a circuit board according to the first example may include a step (preheating step) of heating the resin composition 30a at a temperature lower than the curing temperature after filling the through-hole 14 with the resin composition 30a and before curing the resin composition 30a. For example, prior to curing the resin composition 30a, the resin composition 30a may be preheated at a temperature of usually 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 usually 5 minutes or longer (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes).

[0127] <Step (3)> FIG. 6 is a schematic cross-sectional view for explaining step (3) of the method for manufacturing a circuit board according to the first example of an embodiment of the present invention. Step (3) includes polishing the excess cured product 30 protruding or adhering from the core substrate 10 as shown in FIG. 6. By polishing, the excess cured product 30 is removed, so that the surface of the cured product 30 can be flattened.

[0128] As the polishing method, a method capable of removing the excess cured product 30 protruding or adhering from the core substrate 10 can be adopted. Examples of such polishing methods include buff polishing, belt polishing, and ceramic polishing. Examples of commercially available buff polishing devices include "NT-700IM" manufactured by Ishii Notation Co., Ltd.

[0129] The arithmetic mean roughness (Ra) of the polished surface of the cured product 30 (after thermosetting of the cured product layer) is preferably 300 nm or more, more preferably 350 nm or more, and even more preferably 400 nm or more from the viewpoint of improving the adhesion to 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.

[0130] When performing step (3) after step (2), a heat treatment may be applied to the cured product 30 for the purpose of further increasing the degree of cure of the cured product 30 before step (3) after step (2). The temperature in the heat treatment may conform to the curing temperature described above. The specific heat treatment temperature is preferably 120 °C or higher, more preferably 130 °C or higher, still more preferably 150 °C or higher, and preferably 245 °C or lower, more preferably 220 °C or lower, still more preferably 200 °C or lower. The heat treatment time is preferably 5 minutes or longer, more preferably 10 minutes or longer, still more preferably 15 minutes or longer, and preferably 90 minutes or shorter, more preferably 70 minutes or shorter, still more preferably 60 minutes or shorter.

[0131] Also, when performing step (3) before step (2), a pre-heat treatment may be applied by heating at a temperature lower than the curing temperature of the resin composition before step (3). The temperature in the pre-heat treatment is preferably 100 °C or higher, more preferably 110 °C or higher, still more preferably 120 °C or higher, and preferably 245 °C or lower, more preferably 220 °C or lower, still more preferably 200 °C or lower. The heat treatment time is preferably 5 minutes or longer, more preferably 10 minutes or longer, still more preferably 15 minutes or longer, and preferably 90 minutes or shorter, more preferably 70 minutes or shorter, still more preferably 60 minutes or shorter.

[0132] <Step (4)> Step (4) includes performing a roughening treatment (desmear treatment) on the polished surface of the cured product. The procedure and conditions of the roughening step are not particularly limited, and for example, the procedures and conditions used in the manufacturing method of a multilayer printed wiring board can be adopted. As the roughening step, for example, a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing liquid may be performed in this order to roughen the cured product 30.

[0133] Examples of the swelling liquid that can be used in the roughening process include, for example, an alkaline solution, a surfactant solution, etc., and an alkaline solution is preferred. As the alkaline solution which is the swelling liquid, a sodium hydroxide solution and a potassium hydroxide solution are more preferred. Examples of commercially available swelling liquids include, for example, "Swelling Dip Security P", "Swelling Dip Security SBU" manufactured by Atotech Japan Co., Ltd.

[0134] The swelling treatment with the swelling liquid can be carried out, for example, by immersing the cured product 30 in the swelling liquid at 30°C to 90°C for 1 minute to 20 minutes. From the viewpoint of suppressing the swelling of the resin constituting the cured product 30 to an appropriate level, it is preferable to immerse the cured product 30 in the swelling liquid at 40°C to 80°C for 5 minutes to 15 minutes.

[0135] Examples of the oxidizing agent that can be used in the roughening treatment with the oxidizing agent include, for example, an alkaline permanganate solution in which potassium permanganate or sodium permanganate is dissolved in an aqueous solution of sodium hydroxide. The roughening treatment with an oxidizing agent such as an alkaline permanganate solution is preferably carried out by immersing the cured product 30 in the solution of the oxidizing agent heated to 60°C to 80°C for 10 minutes to 30 minutes. Also, the concentration of the permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Examples of commercially available oxidizing agents include, for example, alkaline permanganate solutions such as "Concentrate Compact P", "Dosing Solution Security P" manufactured by Atotech Japan Co., Ltd.

[0136] As the neutralizing liquid that can be used in the neutralization treatment, an acidic aqueous solution is preferred. Examples of commercially available neutralizing liquids include, for example, "Reduction Solution Security P" manufactured by Atotech Japan Co., Ltd. The neutralization treatment with the neutralizing liquid can be carried out by immersing the treated surface where the roughening treatment with the oxidizing agent solution has been performed in the neutralizing liquid at 30°C to 80°C for 5 minutes to 30 minutes. From the viewpoint of workability, etc., a method of immersing the cured product 30 where the roughening treatment with the oxidizing agent solution has been performed in the neutralizing liquid at 40°C to 70°C for 5 minutes to 20 minutes is preferred.

[0137] The arithmetic mean roughness (Ra) of the surface of the cured product 30 after the roughening treatment is preferably 300 nm or more, more preferably 350 nm or more, still more preferably 400 nm or more, from the viewpoint of improving the adhesion to the conductor layer. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, still more preferably 1000 nm or less. The surface roughness (Ra) can be measured, for example, using a non-contact surface roughness meter.

[0138] <Step (5)> FIG. 7 is a schematic cross-sectional view for explaining Step (5) of the method for manufacturing a circuit board according to the first example of an embodiment of the present invention. As shown in FIG. 7, Step (5) includes forming a conductor layer 40 on the polished surface of the cured product 30. Here, an example is shown in which the conductor layer 40 is formed not only on the polished surface of the cured product 30 but also on the surrounding surfaces (for example, the surface of the core substrate 10, the surface of the plating layer 20). Further, in FIG. 7, an example is shown 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.

[0139] FIG. 8 is a schematic cross-sectional view for explaining Step (5) of the method for manufacturing a circuit board according to the first example of an embodiment of the present invention. As shown in FIG. 8, Step (5) may include, after forming the conductor layer 40, removing a part of the conductor layer 40, the first metal layer 12, the second metal layer 13, and the plating layer 20 by a process such as etching to form a patterned conductor layer 41.

[0140] Examples of the method for forming the conductor layer 40 include, for example, plating, sputtering, vapor deposition, etc., and among them, the plating method is preferable. In a preferred embodiment, by an appropriate method such as semi-additive method or full-additive method, plating is performed on the surface of the cured product 30 (and the plating layer 20) to form a pattern conductor layer 41 having a desired wiring pattern. As the material of the conductor layer 40, for example, single metals such as gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, indium, etc.; alloys of two or more metals selected from the group of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin and indium can be mentioned. Among them, from the viewpoints of versatility, cost, ease of patterning, etc., it is preferable to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or nickel-chromium alloy, copper-nickel alloy, copper-titanium alloy, and it is more preferable to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or nickel-chromium alloy, and it is even more preferable to use copper.

[0141] Here, an example of the method for forming the pattern conductor layer 41 on the polished surface of the cured product 30 will be described in detail. A plating seed layer is formed on the polished surface of the cured product 30 by electroless plating. Next, an electrolytic plating layer is formed on the formed plating seed layer by electrolytic plating. Then, if necessary, an unnecessary plating seed layer can be removed by a treatment such as etching to form a pattern conductor layer 41 having a desired wiring pattern. After the formation of the pattern conductor layer 41, an annealing treatment may be performed if necessary to improve the adhesion strength of the pattern conductor layer 41. The annealing treatment can be performed, for example, by heating at 150°C to 200°C for 20 minutes to 90 minutes.

[0142] From the perspective of thinning, the thickness of the pattern conductor layer 41 is preferably 70 μm or less, more preferably 60 μm or less, still 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, still more preferably 5 μm or more.

[0143] By the above method, the circuit board 1 including the cured product 30 of the resin composition can be manufactured.

[0144] [12.2. Circuit board according to the second example] The circuit board according to the second example includes a cured product layer formed of a cured product of a resin composition. This cured product layer is preferably formed using a resin sheet. This circuit board is, for example, (i) A step of laminating a resin sheet on an inner layer substrate so that the resin composition layer is joined to the inner layer substrate to form a cured product layer, (ii) A step of drilling the cured product layer, (iii) A step of roughening the surface of the cured product layer, and (iv) A step of forming a conductor layer on the surface of the cured product layer, can be manufactured by a manufacturing method including these steps.

[0145] <Step (i)> Step (i) includes laminating a resin sheet on an inner layer substrate so that the resin composition layer is joined to the inner layer substrate to form a cured product layer. For example, a resin sheet is laminated on an inner layer substrate so that the resin composition layer is joined to the inner layer substrate, and the resin composition layer is thermally cured to form a cured product layer.

[0146] FIG. 9 is a schematic cross-sectional view for explaining step (i) in the manufacturing method of the circuit board according to the second example of an embodiment of the present invention. As shown in FIG. 9, a resin sheet 310 including a support 330 and a resin composition layer 320a provided on the support 330 is prepared. Then, the resin sheet 310 and the inner layer substrate 200 are laminated so that the resin composition layer 320a is joined to the inner layer substrate 200.

[0147] As the inner layer substrate 200, an insulating substrate can be used. Examples of the inner layer substrate 200 include insulating base materials such as glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The inner layer substrate 200 may be an inner layer circuit board in which wirings and the like are formed within its thickness.

[0148] The inner layer substrate 200 shown in this example includes a first conductor layer 420 provided on the first main surface 200a and external terminals 240 provided on the second main surface 200b. The first conductor layer 420 may include a plurality of wirings. However, in the example shown in FIG. 9, only the wirings constituting the coil-shaped conductive structure 400 (see FIG. 12) of the inductor element are shown. The external terminals 240 can be terminals for electrically connecting to an external device or the like (not shown). The external terminals 240 can be configured as a part of a conductor layer provided on the second main surface 200b.

[0149] Examples of the conductor material that can form the first conductor layer 420 and the external terminals 240 include the same materials as those of the conductor layer described in the first example.

[0150] The first conductor layer 420 and the external terminals 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 laminated. Also, the thicknesses of the first conductor layer 420 and the external terminals 240 can be the same as those of the second conductor layer 440 described later.

[0151] The line (L) / space (S) ratio of the first conductor layer 420 and the external terminals 240 is not particularly limited. However, from the viewpoint of reducing surface irregularities and obtaining a cured product 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, still more preferably 300 / 300 μm or less, and even more preferably 200 / 200 μm or less. The lower limit of the line / space ratio is not particularly limited, but from the viewpoint of favorably embedding the resin composition layer into the space, it is preferably 1 / 1 μm or more.

[0152] The inner layer substrate 200 may have a plurality of through holes 220 penetrating the inner layer substrate 200 from the first main surface 200a to the second main surface 200b. A through hole inner wiring 220a is provided in the through hole 220. The through hole inner wiring 220a electrically connects the first conductor layer 420 and the external terminal 240.

[0153] The bonding between the resin composition layer 320a and the inner layer substrate 200 can be performed, for example, by thermocompression bonding the resin sheet 310 to the inner layer substrate 200 from the support 330 side. Examples of the member for thermocompression bonding the resin sheet 310 to the inner layer substrate 200 (hereinafter also referred to as "thermocompression bonding member") include a heated metal plate (such as a stainless steel (SUS) mirror plate) or a metal roll (SUS roll). Note that it is preferable to press through a sheet made of an elastic material such as heat-resistant rubber so that the resin sheet 310 sufficiently follows the unevenness on the surface of the inner layer substrate 200, rather than directly contacting and pressing the thermocompression bonding member against the resin sheet 310.

[0154] The temperature during thermocompression bonding is preferably in the range of 80°C to 160°C, more preferably in the range of 90°C to 140°C, and even more preferably in the range of 100°C to 120°C. The pressure during thermocompression bonding is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably in the range of 0.29 MPa to 1.47 MPa. The time during thermocompression bonding is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. The bonding between the resin sheet and the inner layer substrate is preferably performed under reduced pressure conditions of 26.7 hPa or less.

[0155] The bonding between the resin composition layer 320a of the resin sheet 310 and the inner layer substrate 200 can be performed by a commercially available vacuum laminator. Examples of the commercially available vacuum laminator include a vacuum pressurizing type laminator manufactured by Meiki Seisakusho Co., Ltd. and a vacuum applicator manufactured by Nichco Materials Co., Ltd.

[0156] After the resin sheet 310 and the inner layer substrate 200 are joined, under normal pressure (atmospheric pressure), for example, the laminated resin sheet 310 may be smoothed by pressing a heat - crimping member from the support 330 side. The pressing conditions for the smoothing process can be the same as the heat - crimping conditions for the above lamination. The smoothing process can be performed by a commercially available laminator. Note that the lamination and the smoothing process may be continuously performed using the above - mentioned commercially available vacuum laminator.

[0157] FIG. 10 is a schematic cross - sectional view for explaining step (i) in the method for manufacturing a circuit board according to a second example of an embodiment of the present invention. After laminating the resin sheet 310 on the inner layer substrate 200, the resin composition layer 320a is thermally cured to form a cured product layer. In this example, as shown in FIG. 10, the resin composition layer 320a joined to the inner layer substrate 200 is thermally cured to form the first cured product layer 320.

[0158] The thermal curing conditions of 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, still more preferably 150°C or higher, and preferably 245°C or lower, more preferably 220°C or lower, still more preferably 200°C or lower. The curing time is preferably 5 minutes or longer, more preferably 10 minutes or longer, still more preferably 15 minutes or longer, and preferably 120 minutes or shorter, more preferably 110 minutes or shorter, still more preferably 100 minutes or shorter.

[0159] The support 330 may be removed between the thermal curing in step (i) and step (ii), or may be peeled off after step (ii).

[0160] The arithmetic mean roughness (Ra) before the roughening treatment of the cured product layer is preferably 300 nm or more, more preferably 350 nm or more, still more preferably 400 nm or more, from the viewpoint of improving the adhesion with plating. The upper limit is preferably 1000 nm or less, more preferably 900 nm or less, still more preferably 800 nm or less. The surface roughness (Ra) can be measured, for example, using a non - contact type surface roughness meter.

[0161] Step (i) may include forming a cured product layer by applying a resin composition onto the inner layer substrate 200 using a coating device such as a die coater instead of the resin sheet and thermally curing it.

[0162] <Step (ii)> FIG. 11 is a schematic cross-sectional view for explaining Step (ii) in the method for manufacturing a circuit board according to a second example of an embodiment of the present invention. As shown in FIG. 11, Step (ii) includes drilling the first cured product layer 320 to form via holes 360. The via holes 360 can serve as a path for electrically connecting the first conductor layer 420 and a second conductor layer 440 described later. The formation of the via holes 360 may be carried out using, for example, a drill, a laser, a plasma, or the like. The dimensions and shape of the holes may be appropriately determined according to the design of the printed wiring board.

[0163] <Step (iii)> In Step (iii), the surface of the cured product layer in which the via holes are formed is roughened. The roughening treatment in Step (iii) can be performed in the same manner as described in Step (4) of the first example.

[0164] The arithmetic mean roughness (Ra) of the cured product layer after the roughening treatment is preferably 300 nm or more, more preferably 350 nm or more, and still more preferably 400 nm or more from the viewpoint of improving the adhesion to plating. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and still more preferably 1000 nm or less. The surface roughness (Ra) can be measured using, for example, a non-contact surface roughness meter.

[0165] <Step (iv)> FIG. 12 is a schematic cross-sectional view for explaining Step (iv) in the method for manufacturing a circuit board according to a second example of an embodiment of the present invention. As shown in FIG. 12, in Step (iv), a second conductor layer 440 is formed on the first cured product layer 320.

[0166] As the conductor material that can constitute the second conductor layer 440, the same materials as those of the conductor layer described in the first example can be mentioned.

[0167] From the perspective of thinning, the thickness of the second conductor layer 440 is preferably 70 μm or less, more preferably 60 μm or less, still 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, still more preferably 5 μm or more.

[0168] 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, for example, 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, the second conductor layer 440 including a desired wiring pattern can be formed. In addition, by this process, the in-via wiring 360a is formed in the via hole 360 together.

[0169] The first conductor layer 420 and the second conductor layer 440 may be provided in a spiral shape, as shown in an example in FIGS. 13 to 15 described later. In one example, one end on the center side of the spiral wiring portion of the second conductor layer 440 is electrically connected to one end on the center side of the spiral wiring portion of the first conductor layer 420 by the in-via wiring 360a. The other end on the outer peripheral side of the spiral wiring portion of the second conductor layer 440 is electrically connected to the land 420a of the first conductor layer 42 by the in-via wiring 360a. Therefore, the other end on the outer peripheral side of the spiral wiring portion of the second conductor layer 440 is electrically connected to the external terminal 240 via the in-via wiring 360a, the land 420a, and the through-hole inner wiring 220a.

[0170] The coil-shaped conductive structure 400 is composed of a spiral wiring portion that is a part of the first conductor layer 420, a spiral wiring portion that is a part of the second conductor layer 440, and an in-wire 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.

[0171] After step (iv), a step of further forming a cured product layer on the conductor layer may be performed. Specifically, as shown in an example in FIG. 14, a second cured product layer 340 is formed on the first cured product layer 320 on which the second conductor layer 440 and the in-wire wiring 360a are formed. The second cured product layer may be formed by the same steps as the steps already described. By the above method, a circuit board 100 including the first cured product layer 320 and the second cured product layer 340 formed of a cured product of the resin composition can be manufactured.

[0172] [13. Inductor Substrate] The inductor substrate includes the circuit board described above. Such an inductor substrate may have an inductor pattern formed of a conductor at least partially around the cured product of the resin composition when including a circuit board obtained by the manufacturing method of the circuit board according to the above-described first example. In this case, the inductor substrate may include, for example, an inductor element composed of an inductor pattern formed of at least a part of the first metal layer 12, the second metal layer 13, the plating layer 20, and the pattern conductor layer 41, and a core portion formed of the cured product 30 surrounded by this inductor pattern. Such an inductor substrate can apply, for example, those described in Japanese Patent Application Laid-Open No. 2016-197624.

[0173] Further, when including a circuit board obtained by the manufacturing method of the circuit board according to the second example, the inductor substrate may have a cured product layer and a conductive structure at least partially embedded in this cured product layer. And this inductor substrate may include an inductor element composed of the conductive structure and a part of the cured product layer extending in the thickness direction of the cured product layer and surrounded by the conductive structure.

[0174] FIG. 13 is a schematic plan view of a circuit board 100 included in an inductor substrate, as viewed from one side in the thickness direction thereof. FIG. 14 is a schematic view showing a cut end face of the circuit board 100 cut at the position indicated by the II-II chain line shown in FIG. 13. FIG. 15 is a schematic plan view for explaining the configuration of a first conductor layer 420 of the circuit board 100 included in the inductor substrate.

[0175] As shown as an example in FIGS. 13 and 14, the circuit board 100 may be a build-up wiring board having a plurality of cured layers (a first cured layer 320 and a second cured layer 340) and a plurality of conductor layers (a first conductor layer 420 and a second conductor layer 440), that is, a build-up cured layer and a build-up conductor layer. Further, the circuit board 100 includes an inner layer substrate 200.

[0176] As shown in FIG. 14, the first cured layer 320 and the second cured layer 340 constitute a magnetic portion 300 that can be regarded as an integral cured layer. Therefore, the coil-shaped conductive structure 400 is provided such that at least a part thereof is embedded in the magnetic portion 300. That is, in the circuit board 100 shown in this example, the inductor element is composed of the coil-shaped conductive structure 400 and a core portion that extends in the thickness direction of the magnetic portion 300 and is a part of the magnetic portion 300 surrounded by the coil-shaped conductive structure 400.

[0177] As shown as an example in FIG. 15, the first conductor layer 420 includes a spiral wiring portion for forming the coil-shaped conductive structure 400 and a rectangular land 420a that is electrically connected to the through-hole inner wiring 220a. In the example shown here, the spiral wiring portion includes a bent portion that bends at a right angle to the linear portion and a detour portion that detours around the land 420a. Further, the spiral wiring portion of the first conductor layer 420 has a shape in which the overall contour is substantially rectangular and is wound counterclockwise from the center side toward the outside.

[0178] 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 forming a coil-shaped conductive structure 400. In FIG. 13 or FIG. 14, the spiral wiring portion includes a bent portion that bends at a right angle to the linear portion. In FIG. 13 or FIG. 14, the spiral wiring portion of the second conductor layer 44 has a substantially rectangular overall contour and is wound clockwise from the center side toward the outside.

[0179] The above-described inductor substrate can be used as a wiring board for mounting electronic components such as semiconductor chips, and can also be used as a (multi-layer) printed wiring board using such a wiring board as an inner layer substrate. Further, such a wiring board can be used as a chip inductor component obtained by singulating the wiring board, and can also be used as a printed wiring board on which the chip inductor component is surface-mounted.

[0180] Also, various types of semiconductor devices can be manufactured using such a wiring board. A semiconductor device including such a wiring board can be suitably used in electrical products (for example, computers, mobile phones, digital cameras, and televisions, etc.) and vehicles (for example, motorcycles, automobiles, trains, ships, and airplanes, etc.).

Example

[0181] Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples shown below. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "mass%" unless otherwise specified. Also, the operations described below were performed at room temperature (23°C), normal pressure (1 atm), and in the air unless otherwise specified.

[0182] [Example 1] Soft magnetic nanoalloy powder a1 (FeSiCr-based alloy powder "G00129D" manufactured by JFE Minerals Co., Ltd., average particle size 0.2 μm, true specific gravity 7, specific surface area 9 m 230 parts by mass of / g), soft magnetic powder b1 (manufactured by Epson Atmix Corporation, FeSiCr-based alloy powder "AW02-08PF03", average particle size 3 μm, true specific gravity 7, specific surface area 0.65 m 2 70 parts by mass of / g), liquid epoxy resin c1 ("ZX-1059", a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., specific gravity 1.1) 3 parts by mass, liquid epoxy resin c2 ("EP-4088S", glycidyl ether type aliphatic epoxy resin, manufactured by ADEKA Corporation, specific gravity 1.1) 3 parts by mass, liquid epoxy resin c3 ("630", glycidyl ether type aromatic epoxy resin, manufactured by Mitsubishi Chemical Corporation, specific gravity 1.1) 1 part by mass, and a curing accelerator ("2MZA-PW", imidazole-based curing accelerator, manufactured by Shikoku Kasei Co., Ltd., specific gravity 1.0) 1 part by mass were mixed and uniformly dispersed with a high-speed rotary mixer to produce a paste-like resin composition 1.

[0183] [Example 2] Instead of soft magnetic powder b1, 70 parts by mass of soft magnetic powder b2 (FeSiCr-based alloy powder "KUAMET 6B2-53um" manufactured by Epson Atmix Corporation, average particle size 25 μm, true specific gravity 7, specific surface area 0.5 m 2 / g) was used, and resin composition 2 was produced in the same manner as in Example 1.

[0184] [Example 3] Instead of soft magnetic powder b1, 70 parts by mass of soft magnetic powder b3 (FeSiCr-based alloy powder "KUAMET NC1-53um" manufactured by Epson Atmix Corporation, average particle size 25 μm, true specific gravity 7, specific surface area 0.55 m 2 / g) was used, and resin composition 3 was produced in the same manner as in Example 1.

[0185] [Example 4] Instead of soft magnetic powder b1, 70 parts by mass of soft magnetic powder b4 (FeNi-based alloy powder "Fe-50Ni" manufactured by DOWA Electronics Co., Ltd., average particle size 3 μm, true specific gravity 8, specific surface area 0.8 m 2 / g) was used, and resin composition 4 was produced in the same manner as in Example 1.

[0186] [Example 5] A resin composition 5 was produced in the same manner as in Example 1, except that 70 parts by mass of soft magnetic powder b5 (MnZn ferrite powder "MZ05S" manufactured by Powdertech Co., Ltd., average particle size 5 μm, true specific gravity 5, specific surface area 0.4 m 2 / g) was used instead of soft magnetic powder b1.

[0187] [Example 6] A resin composition 6 was produced in the same manner as in Example 1, except that 70 parts by mass of soft magnetic powder b6 (MnZn ferrite powder "MZ10S" manufactured by Powdertech Co., Ltd., average particle size 10 μm, true specific gravity 5, specific surface area 0.3 m 2 / g) was used instead of soft magnetic powder b1.

[0188] [Example 7] A resin composition 7 was produced in the same manner as in Example 1, except that 70 parts by mass of soft magnetic powder b7 (Mn ferrite powder "M05S" manufactured by Powdertech Co., Ltd., average particle size 5 μm, true specific gravity 5, specific surface area 0.5 m 2 / g) was used instead of soft magnetic powder b1.

[0189] [Example 8] A resin composition 8 was produced in the same manner as in Example 1, except that the amount of soft magnetic nanoalloy powder a1 was changed to 5 parts by mass and the amount of soft magnetic powder b1 was changed to 95 parts by mass.

[0190] [Example 9] A resin composition 9 was produced in the same manner as in Example 1, except that the amount of soft magnetic nanoalloy powder a1 was changed to 50 parts by mass and the amount of soft magnetic powder b1 was changed to 50 parts by mass.

[0191] [Example 10] A resin composition 10 was produced in the same manner as in Example 1, except that 30 parts by mass of soft magnetic nanoalloy powder a2 (FeSiCr-based alloy powder "G00212D" manufactured by JFE Minerals Co., Ltd., average particle size 0.5 μm, true specific gravity 7, specific surface area 3 m 2 / g) was used instead of soft magnetic nanoalloy powder a1.

[0192] [Example 11] Resin composition 11 was produced in the same manner as in Example 1, except that 30 parts by mass of soft magnetic nano-alloy powder a3 (FeSiCr-based alloy powder "G00220DC" manufactured by JFE Minerals Co., Ltd., average particle size 0.7 μm, true specific gravity 8, specific surface area 5 m 2 / g) was used instead of soft magnetic nano-alloy powder a1.

[0193] [Comparative Example 1] Resin composition 12 was produced in the same manner as in Example 1, except that 30 parts by mass of soft magnetic nano-powder a4 (Mn-based ferrite powder "M001" manufactured by Powdertech Co., Ltd., average particle size 0.2 μm, true specific gravity 5, specific surface area 11 m 2 / g) was used instead of soft magnetic nano-alloy powder a1.

[0194] [Comparative Example 2] Resin composition 13 was produced in the same manner as in Example 1, except that 30 parts by mass of soft magnetic nano-powder a5 (MnMgSr-based ferrite powder "E001" manufactured by Powdertech Co., Ltd., average particle size 0.2 μm, true specific gravity 5, specific surface area 15 m 2 / g) was used instead of soft magnetic nano-alloy powder a1.

[0195] [Comparative Example 3] Resin composition 14 was produced in the same manner as in Example 1, except that 5 parts by mass of soft magnetic nano-powder a4 (Mn-based ferrite powder "M001" manufactured by Powdertech Co., Ltd., average particle size 0.2 μm, true specific gravity 5, specific surface area 11 m 2 / g) was used instead of soft magnetic nano-alloy powder a1, and the amount of soft magnetic powder b1 was changed to 95 parts by mass.

[0196] [Comparative Example 4] Resin composition 15 was produced in the same manner as in Example 1, except that 50 parts by mass of soft magnetic nano-powder a4 (Mn-based ferrite powder "M001" manufactured by Powdertech Co., Ltd., average particle size 0.2 μm, true specific gravity 5, specific surface area 11 m 2 / g) was used instead of soft magnetic nano-alloy powder a1, and the amount of soft magnetic powder b1 was changed to 50 parts by mass.

[0197] [Comparative Example 5] Instead of the soft magnetic nanoalloy powder a1, 5 parts by mass of silica (silica "A200" manufactured by Nippon Aerosil Co., Ltd., average particle size 0.1 μm, true specific gravity 2.2, specific surface area 200 m 2 / g) was used, and the amount of the soft magnetic powder b1 was changed to 95 parts by mass. The resin composition 16 was produced in the same manner as in Example 1 except for this change.

[0198] [Test Example 1: Measurement of relative permeability] As a support, a polyethylene terephthalate (PET) film ("PET501010" manufactured by Lintec Corporation, thickness 50 μm) having a release surface treated with a silicone-based release agent was prepared. Each resin composition was uniformly applied onto the release surface of the PET film with a doctor blade so that the thickness of the resin composition layer after drying would be 100 μm, and a resin sheet was obtained. The obtained resin sheet was heated at 180 °C for 90 minutes to thermally cure the resin composition layer, and the support was peeled off to obtain a sheet-like cured product. The obtained cured product was cut into a toroidal test piece having an outer diameter of 19 mm and an inner diameter of 9 mm to obtain an evaluation sample. The relative permeability (μ') of this evaluation sample was measured at a measurement frequency of 100 MHz and at room temperature of 23 °C using an analyzer ("16454A E4991B" manufactured by Keysight Technologies).

[0199] [Test Example 2: Measurement of thixotropy index] Each resin composition was maintained at 25 °C ± 0.1 °C, and the viscosity of each resin composition was measured using an E-type viscometer ("RE-80U" manufactured by Toki Sangyo Co., Ltd., 3° × R9.7 cone rotor (measurement sample 0.22 ml)). The viscosity measurement was performed at rotor rotation speeds of 0.5 rpm and 5 rpm, respectively. Using the viscosity η 0.5 measured at a rotor rotation speed of 0.5 rpm and the viscosity η5 measured at a rotor rotation speed of 5 rpm, the thixotropy index (T.I.) was calculated by the following formula. T.I. = (viscosity η at a rotation speed of 0.5 rpm 0.5 ) / (viscosity η5 at a rotation speed of 5 rpm)

[0200] [Test Example 3: Evaluation of Embeddability] Using an LS-340VTVA type vacuum screen printing machine manufactured by Neuron Precision Industry Co., Ltd., the embeddability of each resin composition was evaluated by the following method. An FR4 substrate (thickness 1 mm) with through-holes having a diameter of 500 μm was prepared. In a vacuum of 25°C and 0.1 Pa, each resin composition was printed on the substrate at a printing speed of 150 mm / s using a urethane squeegee, and the above-mentioned through-holes were filled with the resin composition. After printing, the resin composition was cured at 190°C for 90 minutes. Then, the substrate was cut at the portion where the through-holes were formed, and the cross-section was observed to evaluate the embeddability based on the following criteria. "Good": The resin composition passes through the through-hole and is discharged to the back surface of the substrate. "Poor": The resin composition is not discharged to the back surface of the substrate.

[0201] [Results] The results of the above-mentioned examples and comparative examples are shown in the following table. In the following table, the abbreviations have the following meanings. Volume ratio B / A: Volume ratio of soft magnetic nanopowder to soft magnetic powder (soft magnetic powder / soft magnetic nanopowder) Weighted average (volume basis): Weighted average on a volume basis of the BET specific surface area of soft magnetic nanopowder and the BET specific surface area of soft magnetic powder. Weighted average (mass basis): Weighted average on a mass basis of the BET specific surface area of soft magnetic nanopowder and the BET specific surface area of soft magnetic powder.

[0202] [Table 1]

[0203] [Table 2] [Explanation of Symbols]

[0204] 10-core substrate 11-support substrate 12-first metal layer 13 Second metal layer 14 Through hole 20 Plating layer 30a Resin composition 30 Cured product 40 Conductor layer 41 Pattern conductor layer 100 Circuit board 200 Inner layer substrate 200a First main surface 200b Second main surface 220 Through hole 220a Inner wiring in through hole 240 External terminal 300 Magnetic part 310 Resin sheet 320a Resin composition layer 320 First cured product layer 330 Support 340 Second cured product layer 360 Via hole 360a Inner wiring in via hole 400 Coil-shaped conductive structure 420 First conductor layer 420a Land 440 Second conductor layer

Claims

1. (A) BET specific surface area S Ａ is 2m ２ / g or more 10m ２ / g or less alloy magnetic powder, (B) BET specific surface area S Ｂ is 0.1 m ２ / g or more and less than 2 m ２ / g of magnetic powder, and A resin composition containing (C) a binder resin.

2. The resin composition according to claim 1, wherein the volume ratio of component (B) to component (A) ((B) component / (A) component) is 0.9 or more and 20.0 or less.

3. The resin composition according to claim 1 or 2, wherein the total amount of component (A) and component (B) is 50% by volume or more based on 100% by volume of the non-volatile components in the resin composition.

4. The resin composition according to any one of claims 1 to 3, wherein component (A) contains an iron alloy-based powder containing Fe, Si, and Cr.

5. The resin composition according to any one of claims 1 to 4, wherein component (C) contains a thermosetting resin.

6. The resin composition according to any one of claims 1 to 5, wherein component (C) contains an epoxy resin.

7. The resin composition according to claim 6, further containing (D) an epoxy curing accelerator.

8. The resin composition according to any one of claims 1 to 7, wherein the amount of component (C) is 60% by mass or more based on 100% by mass of the resin components in the resin composition.

9. The resin composition according to any one of claims 1 to 8, which is in paste form at 23°C.

10. A cured product of the resin composition according to any one of claims 1 to 9.

11. A resin sheet including a support and a resin composition layer formed of the resin composition according to any one of claims 1 to 9 on the support.

12. A circuit board including a cured product of the resin composition according to any one of claims 1 to 9.

13. A circuit board including a substrate having through-holes and a cured product of the resin composition according to any one of claims 1 to 9 filled in the through-holes.

14. An inductor substrate including the circuit board according to claim 12 or 13. ​

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