resin composition

Abstract

The objective of this invention is to provide a resin composition for obtaining a magnetic material with excellent mechanical strength and specific permeability. The solution is a resin composition containing (A) magnetic powder and (B) a thermosetting resin, wherein component (A) comprises (A-1) ferrite powder with an average particle size of 0.8 μm or less, and (A-2) magnetic powder with an average particle size of 1.5 μm or more, and the volume ratio of component (A-2) to component (A-1) ((A-2) component / (A-1) component) is 0.8 to 34.0.

Description

Technical Field

[0001] This invention relates to a resin composition containing magnetic powder. More specifically, it relates to cured products, resin sheets, circuit boards, and inductor substrates obtained using the resin composition. Prior Technology

[0002] Inductors are widely used in information terminals such as mobile phones and smartphones. Previously, independent inductor components were mounted on a substrate, but in recent years, methods have emerged that use conductor patterns on the substrate to form coils, thus embedding the inductor within the substrate. One known method for embedding inductors within a substrate is to screen-print a magnetic material containing magnetic powder onto a substrate containing wiring to form a hardened layer (Patent Documents 1 and 2). In recent years, to further improve the performance of inductors, there is a demand for improving the magnetic properties of magnetic materials. One method to improve the magnetic properties of magnetic materials is to increase the content of magnetic powder in the material. For example, it is known to use two or more magnetic metal powders with different average particle sizes to increase the powder filling rate and thus improve the magnetic properties of magnetic materials (Patent Document 3). [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-69058 [Patent Document 2] Japanese Patent Application Publication No. 2017-63100 [Patent Document 3] Japanese Patent Application Publication No. 2019-220609 Summary of the Invention

[0004] [The problem that the invention aims to solve]

[0005] However, there is a limit to how increasing the fill rate can improve the specific permeability. Furthermore, increasing the fill rate tends to compromise the mechanical strength of the magnetic material and can easily lead to problems such as cracks, which reduces the production stability of inductor components.

[0006] The objective of this invention is to provide a resin composition for obtaining a magnetic material (hardened material) with excellent mechanical strength and specific permeability. [Methods used to solve problems]

[0007] Through in-depth research to achieve the above-mentioned objectives, the inventors discovered that when ferrite powder is used in a specific proportion as the magnetic powder with an average particle size of less than 0.8 μm and more than 1.5 μm in a thermosetting resin composition containing two types of magnetic powders with an average particle size of less than 0.8 μm, excellent specific permeability can be achieved while maintaining mechanical strength, thus completing the present invention.

[0008] That is, the present invention includes the following contents. [1] A resin composition comprising (A) magnetic powder and (B) thermosetting resin, wherein (A) Composition, comprising (A-1) ferrite powder with an average particle size of less than 0.8 μm, and (A-2) magnetic powder with an average particle size of more than 1.5 μm. The volume ratio of component (A-2) to component (A-1) (component (A-2) / component (A-1)) is 0.8 to 34.0. [2] The resin composition as described in [1] above, wherein the average particle size of component (A-2) is less than 10.0 μm. [3] The resin composition as described in [1] or [2] above, wherein the average particle size of component (A-2) is 2.5 μm or more. [4] The resin composition of any one of [1] to [3] above, wherein the average particle size of component (A-1) is 0.1 μm or more. [5] The resin composition of any of the above [1] to [4] has an average particle size of (A-1) component of less than 0.3 μm. [6] The resin composition of any one of [1] to [5] above, wherein the ratio of the average particle size of component (A-2) to the average particle size of component (A-1) (component (A-2) / component (A-1)) is 10 or more. [7] The resin composition of any one of [1] to [6] above, wherein component (A-1) contains ferrite powder containing at least one element selected from Mn, Zn, Mg, Sr and Ni in addition to Fe. [8] The resin composition of any one of [1] to [7] above, wherein component (A-2) contains magnetic alloy powder. [9] The resin composition of any one of [1] to [8] above, wherein when the non-volatile component in the resin composition is 100% by volume, the content of component (A) is 50% by volume or more.

[10] The resin composition of any of [1] to [9] above, wherein when the non-volatile component in the resin composition is 100% by volume, the content of component (A) is 80% by volume or less.

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

[10] above, wherein the volume ratio of component (A-2) to component (A-1) (component (A-2) / component (A-1)) is 20.0 or less.

[12] In the resin composition described above

[11] , the volume ratio of component (A-2) to component (A-1) (component (A-2) / component (A-1)) is 10.0 or less.

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

[12] above, wherein component (B) contains (B-1) epoxy resin.

[14] The resin composition of any one of [1] to

[13] above, wherein the tensile breaking strength of the hardened resin composition, as determined according to JIS K7127, is 60 MPa or more.

[15] The specific permeability (μ') of the hardened resin composition of any of the above [1] to

[14] is 10.0 or more when the measurement is performed at 23°C with a measurement frequency of 100 MHz.

[16] A hardened resin composition as described in any of [1] to

[15] above.

[17] A resin sheet comprising a support and a resin composition layer disposed on the support, formed of a resin composition as described in any one of [1] to

[15] above.

[18] A circuit board comprising a substrate having through holes and a hardened material of a resin composition as described in any one of [1] to

[15] above, which is filled in the through holes.

[19] A circuit board comprising a hardened layer of a resin composition as described in any one of [1] to

[15] above.

[20] An inductor substrate comprising a circuit substrate as described in

[18] or

[19] above. [Effects of the Invention]

[0009] According to the resin composition of the present invention, a magnetic material (hardened material) with excellent mechanical strength and specific permeability can be obtained. Simple Explanation of the Diagram

[0010] [Figure 1] Figure 1 is a schematic cross-sectional view of a core substrate as an example of a method for manufacturing a circuit board as a first embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view of a core substrate with through holes, which is one example of a method for manufacturing a circuit board as a first embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view showing the appearance of a core substrate with a plating layer formed in a through hole, which is one example of a method for manufacturing a circuit board as a first embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view showing the appearance of a core substrate with resin composition filled in through holes, as an example of a method for manufacturing a circuit board as a first embodiment. [Figure 5] Figure 5 is a schematic cross-sectional view showing the appearance of a core substrate that is thermosetting with a filled resin composition, as an example of a method for manufacturing a circuit board as a first embodiment. [Figure 6] Figure 6 is a schematic cross-sectional view showing the appearance of the core substrate after the hardened material has been ground, as an example of a method for manufacturing a circuit board as a first embodiment. [Fig. 7] Fig. 7 is a schematic cross-sectional view showing a core substrate with a conductor layer formed on a polished surface, as an example of a method for manufacturing a circuit board as a first embodiment. [Fig. 8] Fig. 8 is a schematic cross-sectional view showing the appearance of a core substrate with a patterned conductor layer as an example of a method for manufacturing a circuit board as a first embodiment. [Fig. 9] Fig. 9 is a schematic cross-sectional view of step (A) included in one example of a method for manufacturing a circuit board according to the second embodiment. [Fig. 10] Fig. 10 is a schematic cross-sectional view of step (A) included in one example of a method for manufacturing a circuit board according to the second embodiment. [Fig. 11] Fig. 11 is a schematic cross-sectional view of step (B) included in one example of a method for manufacturing a circuit board according to the second embodiment. [Fig. 12] Fig. 12 is a schematic cross-sectional view of step (D) included in one example of a method for manufacturing a circuit board according to the second embodiment. [Fig. 13] Fig. 13 is a schematic plan view of an inductor component of a circuit board, which is an example of a circuit board manufactured by the method of the second embodiment, viewed from one of its thickness directions. [Fig. 14] Fig. 14 is a schematic diagram showing the cut end face of an inductor component of a circuit board obtained by the manufacturing method of the second embodiment of the circuit board, cut at the position shown by the locking line at point II-II shown in Fig. 13 as an example. [Fig. 15] Fig. 15 is a schematic plan view illustrating the structure of the first conductor layer in an inductor component of a circuit board obtained by the manufacturing method of the circuit board of the second embodiment, as an example. Implementation

[0011] The present invention will now be described in detail according to its suitable embodiments. However, the present invention is not limited to the embodiments and examples described below, and may be implemented in any way without departing from the scope of the claims and their equivalents.

[0012] [Resin Composition] The resin composition of this invention contains (A) magnetic powder and (B) thermosetting resin. The (A) magnetic powder comprises (A-1) ferrite powder with an average particle size of 0.8 μm or less, and (A-2) magnetic powder with an average particle size of 1.5 μm or more. The volume ratio of the magnetic powder in (A-2) to the ferrite powder in (A-1) ((A-2) component / (A-1) component) is 0.8 to 34.0. By using such a resin composition, a magnetic material (cured material) with excellent mechanical strength and specific permeability can be obtained.

[0013] In addition to (A) magnetic powder and (B) thermosetting resin, the resin composition of the present invention may further contain any other components. Examples of such components include (C) other additives and (D) organic solvents. The components contained in the resin composition will be described in detail below.

[0014] <(A) Magnetic Powder> The resin composition of the present invention contains (A) magnetic powder. (A) magnetic powder imparts magnetism to the resin composition. In the resin composition of the present invention, (A) magnetic powder comprises (A-1) ferrite powder with an average particle size of 0.8 μm or less and (A-2) magnetic powder with an average particle size of 1.5 μm or more.

[0015] <(A-1) Ferrite powder with an average particle size of less than 0.8 μm> In the resin composition of this invention, (A) the magnetic powder includes (A-1) ferrite powder with an average particle size of less than 0.8 μm. Ferrite powder refers to magnetic powder composed of composite oxides with iron oxide as the main component. The ferrite powder component (A-1) can be used alone or in combination of two or more types. Ferrite powder is known to be chemically stable, highly corrosion-resistant, has a low risk of fire, is not easily demagnetized, and is generally inexpensive with low acquisition costs.

[0016] The ferrite powder of component (A-1) can be either hard ferrite powder or soft ferrite powder. From the viewpoint that the effects of the present invention are significantly obtained in one embodiment, soft ferrite powder is preferred. The ferrite powder of component (A-1) can be any of spinel ferrite powder, hexagonal ferrite powder, or garnet ferrite powder. From the viewpoint that the effects of the present invention are significantly obtained in one embodiment, spinel ferrite powder is preferred.

[0017] The ferrite powder with composition (A-1) may contain, in addition to Fe, at least one element selected from Mn, Zn, Mg, Sr, Ni, Cu, Ba, Co, Ca, Al, Li, Ti, Pb, and Cd. In one embodiment, the ferrite powder with composition (A-1) preferably contains, in addition to Fe, at least one element selected from Mn, Zn, Mg, Sr, and Ni.

[0018] (A-1) Ferrite powders, for example, include Fe-Mn ferrite powders, Mg-Zn ferrite powders, Mn ferrite powders, Mn-Zn ferrite powders, Mn-Mg ferrite powders, Cu-Zn ferrite powders, Mg-Sr ferrite powders, Mn-Mg-Sr ferrite powders, Ni-Zn ferrite powders, Ni-Zn-Cu ferrite powders, Ba-Zn ferrite powders, Ba-Mg ferrite powders, Ba-Ni ferrite powders, Ba-Co ferrite powders, Ba-Ni-Co ferrite powders, Y-based ferrite powders, etc. The ferrite powder of component (A-1) preferably includes ferrite powder selected from Mn-based ferrite powder, Mn-Zn-based ferrite powder, Mg-Sr-based ferrite powder, Mn-Mg-Sr-based ferrite powder, and Ni-Zn-based ferrite powder.

[0019] The ferrite powder of composition (A-1) is preferably in the form of generally spherical or generally ellipsoidal particles. The ratio (b / a) of the major axis (b) to the minor axis (a) of the ferrite powder particles of composition (A-1) is preferably 2 or less, more preferably 1.5 or less, and even more preferably 1.2 or less.

[0020] The average particle size of the ferrite powder of composition (A-1) is 0.8 μm or less, and from the viewpoint of more significantly obtaining the effects of the invention, it is preferably 0.6 μm or less, more preferably 0.4 μm or less, even 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 ferrite powder of composition (A-1) is not particularly limited, but it is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and particularly preferably 0.12 μm or more. The average particle size of the ferrite powder of composition (A-1) can be the median diameter in a volumetric reference. This average particle size can be determined by laser diffraction / scattering based on the Mie scattering theory. Specifically, a particle size distribution can be generated from a volumetric reference using a laser diffraction / scattering particle size distribution measuring device, and the average particle size can be determined using the median diameter. For optimal sample measurement, it is preferable to use a powder that has been dispersed in water by ultrasonication. Laser diffraction-based particle size distribution measuring devices, such as the Horiba Seisakusho "LA-500" and the Shimadzu Seisakusho "SALD-2200", are suitable.

[0021] The true specific gravity of the ferrite powder of component (A-1) can be, for example, 4.7~5.2 g / cm3.

[0022] Ferrite powders with component (A-1) can be used directly as commercially available products, or two or more can be used in combination. Specific examples of commercially available ferrite powders with component (A-1) include Powdertech's "M001", "MZ001", "E001", and "NZ001".

[0023] Regarding the content (volume %) of ferrite powder in component (A-1), from the viewpoint of more significantly obtaining the effects of the invention, when the non-volatile component in the resin composition is 100 vol%, it is preferably 0.5 vol% or more, 1 vol% or more, more preferably 2 vol% or more, or 3 vol% or more. From the viewpoint of further improving the fracture strength, it is even more preferably 5 vol% or more, 10 vol% or more, particularly preferably 15 vol% or more, or 20 vol% or more. Furthermore, from the viewpoint of more significantly obtaining the effects of the invention, when the non-volatile component in the resin composition is 100 vol%, its upper limit is preferably 50 vol% or less, 45 vol% or less, more preferably 40 vol% or less, or 35 vol% or less. From the viewpoint of further improving the magnetic permeability, it is even more preferably 30 vol% or less, and particularly preferably 27 vol% or less.

[0024] Regarding the content (mass%) of ferrite powder in component (A-1), from the viewpoint of more significantly obtaining the effects of the invention, when the non-volatile component in the resin composition is 100% by mass, it is preferably 0.5% by mass or more, 1% by mass or more, more preferably 2% by mass or more, or 3% by mass or more. From the viewpoint of further improving the fracture strength, it is even more preferably 5% by mass or more, 10% by mass or more, 15% by mass or more, and particularly preferably 20% by mass or more, or 25% by mass or more. Furthermore, from the viewpoint of more significantly obtaining the effects of the invention, when the non-volatile component in the resin composition is 100% by mass, its upper limit is preferably 70% by mass or less, 60% by mass or less, more preferably 50% by mass or less, or 40% by mass or less. From the viewpoint of further improving the magnetic permeability, it is even more preferably 35% by mass or less, and particularly preferably 30% by mass or less.

[0025] <(A-2) Magnetic powder with an average particle size of 1.5 μm or larger> In the resin composition of this invention, (A) magnetic powder includes (A-2) magnetic powder with an average particle size of 1.5 μm or more. The type of magnetic powder in component (A-2) is not particularly limited, and widely known magnetic powders can be used. Component (A-2) can be used alone, or two or more types can be used in combination.

[0026] The magnetic powder in component (A-2) can be either soft magnetic powder or hard magnetic powder. From the viewpoint that the effects of the present invention are significantly obtained in one embodiment, soft magnetic powder is preferred. The magnetic powder in component (A-2) can be, for example, magnetic metal oxide powder or magnetic metal powder.

[0027] Magnetic metal oxide powders are not specifically limited to any particular type. Examples include Fe-Mn ferrite powders, Mg-Zn ferrite powders, Mn ferrite powders, Mn-Zn ferrite powders, Mn-Mg ferrite powders, Cu-Zn ferrite powders, Mg-Sr ferrite powders, Mn-Mg-Sr ferrite powders, Ni-Zn ferrite powders, Ni-Zn-Cu ferrite powders, Ba-Zn ferrite powders, Ba-Mg ferrite powders, Ba-Ni ferrite powders, Ba-Co ferrite powders, Ba-Ni-Co ferrite powders, Y-based ferrite powders, etc.; iron oxide powders such as iron oxide powder (III) and iron(III) oxide powder, etc.

[0028] Magnetic metal powders are not specifically limited to any particular type. Examples include pure iron powder; Fe-Si alloy powders, Fe-Si-Al alloy powders, Fe-Cr alloy powders, Fe-Si-Cr alloy powders, Fe-Ni-Cr alloy powders, Fe-Cr-Al alloy powders, Fe-Ni alloy powders, Fe-Ni-Mo alloy powders, Fe-Ni-Mo-Cu alloy powders, Fe-Co alloy powders, Fe-Ni-Co alloy powders, Co-based amorphous alloy powders, and other crystalline or amorphous magnetic alloy powders.

[0029] The magnetic powder of component (A-2) preferably includes at least one type of magnetic powder selected from ferrite powder and magnetic alloy powder. From the viewpoint of further improving magnetic permeability, it preferably includes at least one type of magnetic alloy powder, and more preferably includes at least one type of magnetic alloy powder selected from Fe-Si-Cr alloy powder and Fe-Ni alloy powder.

[0030] The magnetic powder of component (A-2) is preferably in the form of approximately spherical or approximately ellipsoidal particles. The ratio (b / a) of the major axis (b) to the minor axis (a) of the magnetic powder particles of component (A-2) is preferably 4 or less, more preferably 3 or less, and even more preferably 2 or less.

[0031] The average particle size of the magnetic powder of component (A-2) is 1.5 μm or more. From the viewpoint of more significantly obtaining the effects of the invention, it is preferably 2.0 μm or more, more preferably 2.5 μm or more, even more preferably 2.7 μm or more, and particularly preferably 2.8 μm or more. There is no particular upper limit to the average particle size of the magnetic powder of component (A-2). From the viewpoint of further suppressing magnetic loss, it is preferably 10.0 μm or less, more preferably 7.0 μm or less, even more preferably 5.0 μm or less, and particularly preferably 3.5 μm or less. The average particle size of the magnetic powder of component (A-2) can be the median diameter based on volume. The average particle size of the magnetic powder of component (A-2) can be measured using the same method as the average particle size of the ferrite powder of component (A-1).

[0032] From the viewpoint that the average particle size of the magnetic powder of component (A-2) to the average particle size of the ferrite powder of component (A-1) (component (A-2) / component (A-1)) is more significantly effective, preferably 10 or more, more preferably 15 or more; and preferably 50 or less, more preferably 30 or less.

[0033] (A-2) The specific surface area of ​​the magnetic powder is not particularly limited, but it is preferably 0.05 m² / g or more, more preferably 0.1 m² / g or more, and even more preferably 0.3 m² / g or more. It is also preferably 30 m² / g or less, more preferably 20 m² / g or less, and even more preferably 15 m² / g or less. (A) The specific surface area of ​​the magnetic powder can be determined by the BET method.

[0034] The true specific gravity of the magnetic powder of component (A-2) can be, for example, 4 ~ 10 g / cm³.

[0035] (A-2) The magnetic powder used may be a commercially available magnetic powder. Specific examples of commercially available magnetic powders that may be used include "MZ05" manufactured by Powdertech and "AW08PF3F" manufactured by Epson Atmix. One type of magnetic powder may be used alone, or two or more may be used in combination.

[0036] Regarding the content (volume %) of the magnetic powder in component (A-2), from the viewpoint of more significantly obtaining the effects of the invention, when the non-volatile component in the resin composition is 100 vol%, it is preferably 10 vol% or more, 20 vol% or more, more preferably 25 vol% or more, 30 vol% or more, or 35 vol% or more. From the viewpoint of further improving the magnetic permeability, it is even more preferably 37 vol% or more, and particularly preferably 39 vol% or more. Furthermore, from the viewpoint of more significantly obtaining the effects of the invention, when the non-volatile component in the resin composition is 100 vol%, its upper limit is preferably 80 vol% or less, 75 vol% or less, more preferably 70 vol% or less, or 65 vol% or less. From the viewpoint of further improving the breaking strength, it is even more preferably 60 vol% or less, and particularly preferably 55 vol% or less.

[0037] Regarding the content (mass%) of the magnetic powder in component (A-2), from the viewpoint of more significantly obtaining the effects of the invention, when the non-volatile component in the resin composition is 100% by mass, it is preferably 20% by mass or more, 30% by mass or more, more preferably 40% by mass or more, or 50% by mass or more. From the viewpoint of further improving the magnetic permeability, it is even more preferably 60% by mass or more, and even more preferably 63% by mass or more. Furthermore, from the viewpoint of more significantly obtaining the effects of the invention, when the non-volatile component in the resin composition is 100% by mass, its upper limit is preferably 95% by mass or less, more preferably 90% by mass or less. From the viewpoint of further improving the breaking strength, it is even more preferably 80% by mass or less, and particularly preferably 70% by mass or less.

[0038] The volume ratio of component (A-2) to component (A-1) (component (A-2) / component (A-1)) is 0.8 or more. From the viewpoint of more significantly obtaining the effect of the invention, it is preferably 0.9 or more, more preferably 1.0 or more. From the viewpoint of further improving the magnetic permeability, it is even more preferably 1.1 or more, 1.2 or more, and particularly preferably 1.3 or more, and 1.4 or more. Furthermore, the upper limit is 34.0 or less. From the viewpoint of more significantly obtaining the effect of the invention, it is preferably 30.0 or less, 25.0 or less, more preferably 20.0 or less, and 15.0 or less. From the viewpoint of further improving the fracture strength, it is even more preferably 10.0 or less, 5.0 or less, and particularly preferably 3.0 or less, and 2.5 or less.

[0039] (A) The content (volume %) of the magnetic powder is not particularly limited. However, from the viewpoint of achieving the invention's effects more significantly, when the non-volatile component in the resin composition is 100% by volume, it is preferably 30% by volume or more, more preferably 40% by volume or more, even more preferably 50% by volume or more, 55% by volume or more, and particularly preferably 60% by volume or more, 62% by volume or more, or 65% by volume or more. Furthermore, from the viewpoint of achieving the invention's effects more significantly, when the non-volatile component in the resin composition is 100% by volume, its upper limit is preferably 90% by volume or less, more preferably 85% by volume or less, even more preferably 80% by volume or less, and particularly preferably 75% by volume or less.

[0040] (A) The content (mass%) of the magnetic powder is not particularly limited. However, from the viewpoint of achieving the invention's effects more significantly, when the non-volatile component in the resin composition is 100% by mass, it is preferably 50% by mass or more, 60% by mass or more, more preferably 70% by mass or more, 75% by mass or more, even more preferably 80% by mass or more, 85% by mass or more, and particularly preferably 90% by mass or more, or 92% by mass or more. Furthermore, from the viewpoint of achieving the invention's effects more significantly, when the non-volatile component in the resin composition is 100% by mass, its upper limit is preferably 97% by mass or less, more preferably 95% by mass or less, even more preferably 94% by mass or less, and particularly preferably 93% by mass or less.

[0041] <(A-3) Any Magnetic Powder> (A) may also include any magnetic powder other than (A-1) and (A-2) in (A-3). (A-3) Any magnetic powder may be, for example, magnetic metal oxide powder, magnetic metal powder, etc.

[0042] The content of any magnetic powder in component (A-3) in component (A) should be as small as possible. The content of any magnetic powder in component (A-3) is preferably 5% by volume or less, more preferably 2% by volume or less, and even more preferably 1% by volume or less, relative to 100% by mass of component (A). Furthermore, the content is preferably 5% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, relative to 100% by mass of component (A). Component (A) is particularly preferably free of any magnetic powder in component (A-3) (0% by volume, 0% by mass). That is, component (A) is particularly preferably composed only of components (A-1) and (A-2).

[0043] <(B) Thermosetting Resins> The resin composition of the present invention contains (B) a thermosetting resin. Examples of (B) thermosetting resins include epoxy resins, epoxy acrylate resins, urethane acrylate resins, urethane resins, cyanate ester resins, polyimide resins, benzoxazine resins, unsaturated polyester resins, phenolic resins, melamine resins, polysiloxane resins, phenoxy resins, etc.

[0044] (B) The content (mass%) of the thermosetting resin is not particularly limited. However, from the viewpoint of achieving the invention's effects more significantly, when the non-volatile component in the resin composition is 100% by mass, it is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and particularly preferably 5% by mass or more. Furthermore, from the viewpoint of achieving the invention's effects more significantly, when the non-volatile component in the resin composition is 100% by mass, its upper limit is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less.

[0045] <(B-1) Epoxy Resin> The resin composition of the present invention preferably contains (B-1) epoxy resin as (B) thermosetting resin. (B-1) epoxy resin refers to a resin having epoxy groups.

[0046] (B-1) Examples of epoxy resins include xylenol-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, triphenol-type epoxy resin, naphthol phenolic varnish-type epoxy resin, phenolic phenolic varnish-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 phenolic varnish-type epoxy resin, biphenyl-type epoxy resin, linear aliphatic epoxy resin, epoxy resin with butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, epoxy resin containing spirocyclic ring, cyclohexane-type epoxy resin, cyclohexanediethanol-type epoxy resin, naphthyl ether-type epoxy resin, tris(hydroxymethyl)-type epoxy resin, tetraphenylethane-type epoxy resin, etc. Epoxy resin can be used alone or in combination with two or more types.

[0047] The resin composition preferably contains an epoxy resin having two or more epoxy groups per molecule, as (B-1) epoxy resin. From the viewpoint of significantly obtaining the desired effects of the present invention, the proportion of epoxy resin having two or more epoxy groups per molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more, relative to 100% by mass of the non-volatile components of (B-1) epoxy resin.

[0048] (B-1) The epoxy resin includes a liquid epoxy resin at 25°C (hereinafter referred to as "liquid epoxy resin") and a solid epoxy resin at 25°C (hereinafter referred to as "solid epoxy resin"). The resin composition of the present invention, as the (B-1) epoxy resin, may contain only liquid epoxy resin, or may contain solid epoxy resin in addition to liquid epoxy resin. In a suitable embodiment, it contains only liquid epoxy resin.

[0049] When all epoxy resin is 100% by mass, the liquid epoxy resin is preferably 60% or more by mass, more preferably 80% or more by mass, even more preferably 90% or more by mass, and most preferably 100% by mass.

[0050] Liquid epoxy resin, preferably a liquid epoxy resin having two or more epoxy groups in one molecule.

[0051] Liquid epoxy resins are preferably glycyrrhizic acid type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenolic varnish type epoxy resins, alicyclic epoxy resins with an ester skeleton, cyclohexanediol type epoxy resins, and epoxy resins with a butadiene structure; more preferably glycyrrhizic acid type epoxy resins, bisphenol A type epoxy resins, and bisphenol F type epoxy resins.

[0052] Specific examples of liquid epoxy resins include: DIC's "HP4032", "HP4032D", and "HP4032SS" (naphthalene-type epoxy resin); Mitsubishi Chemical's "828US", "jER828EL" (bisphenol A type epoxy resin), "jER807" (bisphenol F type epoxy resin), and "jER152" (phenolic varnish type epoxy resin); Mitsubishi Chemical's "630" and "630LSD"; ADEKA's "ED-523T" (glycyrrhizic acid type epoxy resin), "EP-3980S" (glycidylamine type epoxy resin), and "EP-4088S" (dicyclopentadiene type epoxy resin); and NIPPON STEEL Chemical & Material Company's "ZX1059" (a mixture of bisphenol A and bisphenol F epoxy resins); Nagase ChemteX's "EX-721" (glycidyl ester epoxy resin); Daicel's "Celloxide 2021P" (an alicyclic epoxy resin with an ester skeleton) and "PB-3600" (an epoxy resin with a butadiene structure); NIPPON STEEL Chemical & Material's "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane), etc.

[0053] Solid epoxy resin, preferably a solid epoxy resin having three or more epoxy groups per molecule, more preferably an aromatic solid epoxy resin having three or more epoxy groups per molecule.

[0054] Solid epoxy resins are preferably bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, naphthol phenolic varnish-type epoxy resins, cresol phenolic varnish-type epoxy resins, dicyclopentadiene-type epoxy resins, triphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthyl ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, phenolary alkyl-type epoxy resins, tetraphenylethane-type epoxy resins, phenolphthalimidine-type epoxy resins, and phenolphthalein-type epoxy resins.

[0055] Specific examples of solid epoxy resins include: DIC's "HP4032H" (naphthalene-type epoxy resin); DIC's "HP-4700" and "HP-4710" (naphthalene-type tetrafunctional epoxy resins); DIC's "N-690" (cresol-phenolic varnish type epoxy resin); DIC's "N-695" (cresol-phenolic varnish type epoxy resin); DIC's "HP-7200," "HP-7200HH," "HP-7200H," and "HP-7200L" (dicyclopentadiene type epoxy resins); and DIC's... "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthyl ether type epoxy resin); "EPPN-502H" (triphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol phenolic varnish type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3000FH", "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.; NIPPON STEEL Chemical & Material Co., Ltd. Material Company's "ESN375" (dihydroxynaphthalene type epoxy resin); Mitsubishi Chemical Company's "YX4000H", "YX4000", "YX4000HK", and "YL7890" (bi-xylenol type epoxy resin); Mitsubishi Chemical Company's "YL6121" (biphenyl type epoxy resin); Mitsubishi Chemical Company's "YX8800" (anthracene type epoxy resin); Mitsubishi Chemical Company's "YX7700" (phenolic alkyl type epoxy resin); [The text abruptly ends here, likely due to an incomplete sentence or missing information.] The following epoxy resins are available: "PG-100" and "CG-500" manufactured by Hanwa Gas Chemical Co., Ltd.; "YL7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YL7800" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "jER1010" (bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; and "WHR991S" (phenylbenzylmethyllactam type epoxy resin) manufactured by Nippon Kayaku Co., Ltd. These resins can be used individually or in combination of two or more.

[0056] When solid epoxy resin and liquid epoxy resin are used together as (B-1) epoxy resin, the mass ratio of solid epoxy resin to 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, even more preferably 0.1 or less, even more preferably 0.05 or less, and most preferably 0.01 or less.

[0057] (B-1) 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., even more preferably 80 g / eq. to 2000 g / eq., and even more preferably 110 g / eq. to 1000 g / eq. Epoxy equivalent is the resin mass relative to one epoxy group equivalent. This epoxy equivalent can be determined according to JIS K7236.

[0058] (B-1) The weight-average molecular weight (Mw) of the epoxy resin is preferably 100-5000, more preferably 250-3000, and even more preferably 400-1500, from the viewpoint of significantly achieving the desired effects of the present invention. The weight-average molecular weight of the resin can be determined by gel permeation chromatography (GPC) as a value converted to polystyrene.

[0059] (B-1) The content (mass%) of epoxy resin is not particularly limited. However, from the viewpoint of achieving the invention's effects more significantly, when the non-volatile component in the resin composition is 100% by mass, it is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and particularly preferably 5% by mass or more. Furthermore, from the viewpoint of achieving the invention's effects more significantly, when the non-volatile component in the resin composition is 100% by mass, its upper limit is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less.

[0060] <(B-2) Epoxy Curing Accelerator> When the resin composition of the present invention contains (B-1) epoxy resin as (B) thermosetting resin, it may further contain (B-2) epoxy curing accelerator as an optional component. The (B-2) epoxy curing accelerator has the function of promoting the curing of (B-1) epoxy resin.

[0061] (B-2) Epoxy curing accelerators, such as imidazole-based, phosphorus-based, urea-based, guanidine-based, metal-based, and amine-based accelerators, etc. In one embodiment, (B-2) epoxy curing accelerators preferably include imidazole-based accelerators. (B-2) Epoxy curing accelerators can be used alone or in combination of two or more.

[0062] Imidazole-based hardening accelerators include, for example, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole ontium trimellitate, 1-cyanoethyl-2-phenylimidazole ontium trimellitate, and 2,4-diamino-6-[2'-methylimidazole-(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-phenylimidazolyl isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazolium, 2-phenyl-4-methyl-5-hydroxymethylimidazolium, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline and other imidazole compounds and adducts of imidazole compounds with epoxy resins.

[0063] Imidazole is a hardening accelerator, and commercially available products can also be used, such as "1B2PZ", "2MZA-PW" and "2PHZ-PW" manufactured by Shikoku Chemical Industry Co., Ltd., and "P200-H50" manufactured by Mitsubishi Chemical Co., Ltd.

[0064] Phosphorus-based hardening accelerators include, for example, aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, bis(tetrabutylphosphonium)phenylpyridine tetraphosphate, tetrabutylphosphonium hydrogen hexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butylmethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, and p-tolyltriphenylphosphonium tetra-p- Aromatic phosphonium salts of tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetrap-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, etc.; aromatic phosphine / borane complexes of triphenylphosphine / triphenylborane, etc.; aromatic phosphine / quinone addition reactants of triphenylphosphine / p-benzoquinone, etc.; tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2- Aliphatic phosphines such as butylene(3-methyl-2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine; dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, phenoxy(4-ethylphenyl)phosphine, phenoxy(4-propylphenyl)phosphine, phenoxy(4-isopropylphenyl)phosphine, phenoxy(4-butylphenyl)phosphine, phenoxy(4-tert-butylphenyl)phosphine, phenoxy(2,4-dimethylphenyl)phosphine, phenoxy(2,5-dimethylphenyl)phosphine, phenoxy(4-ethylphenyl)phosphine, phenoxy(4- ...methylphenyl)phosphine, phenoxy(4-ethylphenyl)phosphine, phenoxy(4-methylphenyl)phosphine, phenoxy(4-ethylphenyl)phosphine, phenoxy(4-methylphenyl)phosphine, phenoxy(4-ethyl Aromatic phosphines such as (2,6-dimethylphenyl)phosphine, trimethylphenyl)phosphine, trimethylphenyl)phosphine, trimethylphenyl)phosphine, trimethylphenyl-4-ethoxyphenyl)phosphine, trimethylphenyl)phosphine, 2-methoxyphenyl)phosphine, trimethyl ...

[0065] Urea is a type of hardening accelerator, such as aliphatic dimethylureas including 1,1-dimethylurea; 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, 3-cyclooctyl-1,1-dimethylurea, etc.; 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-(3,4-dimethylphenyl)-1,1- Aromatic dimethylureas such as 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-epenylphenyl)bis(N',N'-dimethylurea), N,N-(4-methyl-1,3-epenylphenyl)bis(N',N'-dimethylurea)[toluenebisdimethylurea], etc.

[0066] Guanidine-based hardening accelerators include, for example, 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-methylbiguanidine, 1-ethylbiguanidine, 1-n-butylbiguanidine, 1-n-octadecylbiguanidine, 1,1-dimethylbiguanidine, 1,1-diethylbiguanidine, 1-cyclohexylbiguanidine, 1-allylbiguanidine, 1-phenylbiguanidine, 1-(o-tolyl)biguanidine, etc.

[0067] Metal-based hardening accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organocobalt complexes such as acetoacetone cobalt(II) and acetoacetone cobalt(III); organocopper complexes such as acetoacetone copper(II); organozinc complexes such as acetoacetone zinc(II); organoiron complexes such as acetoacetone iron(III); organonickel complexes such as acetoacetone nickel(II); and organomanganese complexes such as acetoacetone manganese(II). Organometallic salts include, for example, zinc octanoate, tin octanoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0068] Amine-based hardening accelerators, such as trialkylamines like triethylamine and tributylamine; 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6'-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc.

[0069] Amine-based hardening accelerators can also be used, such as "MY-25" manufactured by Ajinomoto Fine-Techno.

[0070] (B-2) The content (mass%) of epoxy curing accelerator is not particularly limited, but when the non-volatile component in the resin composition is 100% by mass, it is preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 2% by mass or less, and particularly preferably 1% by mass or less. Furthermore, the lower limit may be, for example, 0% by mass or more, 0.01% by mass or more, 0.1% by mass or more, 0.5% by mass or more, etc.

[0071] <(B-3) Epoxy Hardener> When the resin composition of the present invention contains (B-1) epoxy resin as (B) thermosetting resin, it may further contain (B-3) epoxy curing agent as an optional component. The (B-3) epoxy curing agent has the function of reacting with (B-1) epoxy resin to cure the resin composition.

[0072] (B-3) Epoxy curing agents are not specifically limited, but may include phenolic curing agents, carbodiimide curing agents, acid anhydride curing agents, amine curing agents, benzoxazine curing agents, cyanate ester curing agents, thiol curing agents, etc. (B-3) Epoxy curing agents may be used alone or in combination of two or more. (B-3) Epoxy curing agents preferably include phenolic curing agents.

[0073] There are no special restrictions on phenolic curing agents, but biphenyl-type curing agents, naphthalene-type curing agents, phenolic varnish-type curing agents, naphthyl ether-type curing agents, and phenolic curing agents containing a triazine skeleton are preferred. Specifically, examples include biphenyl-type hardeners such as "MEH-7700", "MEH-7810", and "MEH-7851" (manufactured by Meiwa Kasei Corporation); naphthalene-type hardeners such as "NHN", "CBN", and "GPH" (manufactured by Nippon Kayaku Co., Ltd.); "SN170", "SN180", "SN190", "SN475", "SN485", "SN495", "SN375", and "SN395" (manufactured by Nippon Steel Chemical Co., Ltd.); "EXB9500" (manufactured by DIC Corporation); phenolic varnish hardener "TD2090" (manufactured by DIC Corporation); and naphthyl ether-type hardener "EXB-6000" (manufactured by DIC Corporation). Specific examples of phenolic curing agents containing a triazine skeleton include "LA3018", "LA7052", "LA7054", and "LA1356" (manufactured by DIC). Naphthalene-type curing agents and phenolic curing agents containing a triazine skeleton are particularly preferred.

[0074] Carbodiimide curing agents include those having one or more, preferably two or more, carbodiimide structures within one molecule. Examples include aliphatic bis(t-butylcarbodiimide) and cyclohexanebis(methylene-t-butylcarbodiimide); aromatic bis(xylylcarbodiimide); and aliphatic poly(hexamethylenecarbodiimide), trimethylhexamethylenecarbodiimide, polycyclohexylcarbodiimide, poly(methylene biscyclohexylcarbodiimide), and poly(isophoronecarbodiimide). Carbodiimides; poly(phenylcarbodiimide), poly(naphthylcarbodiimide), poly(tolylcarbodiimide), poly(methyldiisopropylphenylcarbodiimide), poly(triethylphenylcarbodiimide), poly(diethylphenylcarbodiimide), poly(triisopropylphenylcarbodiimide), poly(diisopropylphenylcarbodiimide), poly(xylylcarbodiimide), poly(tetramethylxylylcarbodiimide), poly(methylenexylphenylcarbodiimide), poly[methylenebis(methylphenyl)carbodiimide] and other aromatic polycarbodiimides, etc.

[0075] Commercially available carbodiimide-based curing agents include, for example, "Carbodilite V-02B", "Carbodilite V-03", "Carbodilite V-04K", "Carbodilite V-07" and "Carbodilite V-09" manufactured by Nisshinbo Chemical Co., Ltd.; and "Stabaxol P", "Stabaxol P400" and "Hycasyl 510" manufactured by Rhein Chemie Co., Ltd.

[0076] Anhydride-based curing agents include curing agents having one or more anhydride groups per molecule, preferably curing agents having two or more anhydride groups per molecule. Specific examples of anhydride-based curing agents include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl norbornene dianhydride, hydrogenated methyl norbornene dianhydride, trialkyltetrahydrophthalic anhydride, dodecenylsuccinic anhydride, 5-(2,5-di-side-oxytetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, phenylpyrithione, and diphenyltricarboxylic anhydride. Polymer anhydrides such as benzophenone tetracarboxylic dianhydride, biphenyl tetracarboxylic dianhydride, naphthalene tetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenyltricarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-di-side-oxy-3-furanyl)-naphtho[1,2-C]furan-1,3-dione, ethylene glycol bis(triphenylamine), and styrene / maleic acid resin copolymerized from styrene and maleic acid. Commercially available anhydride-based hardeners include: "HNA-100", "MH-700", "MTA-15", "DDSA", and "OSA" manufactured by New Japan Rika Co., Ltd.; "YH-306" and "YH-307" manufactured by Mitsubishi Chemical Co., Ltd.; and "HN-2200" and "HN-5500" manufactured by Hitachi Chemical Co., Ltd.

[0077] Amine-based curing agents include those having one or more, preferably two or more, amine groups per molecule, such as aliphatic amines, polyether amines, alicyclic amines, and aromatic amines. Aromatic amines are particularly preferred from the viewpoint of achieving the desired effects of this invention. The amine-based curing agent is preferably a primary or secondary amine, more preferably a primary amine. Specific examples of amine-based curing agents include 4,4'-methylenebis(2,6-dimethylaniline), 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, m-phenylenediamine, m-xylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, and 2,2-bis(3-amino-4-hydroxybenzidine). 2,2-bis(4-aminophenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethyldiamine, 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) benzoxide, bis(4-(3-aminophenoxy)phenyl) benzoxide, etc. Amine-based hardeners can also be commercially available products, such as SEIKA's "SEIKACURE-S", Nippon Kayaku Co., Ltd.'s "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD AA", "KAYAHARD AB", "KAYAHARD AS", and Mitsubishi Chemical Co., Ltd.'s "Epicure W".

[0078] Specific examples of benzoxazine-based hardeners include "JBZ-OP100D" and "ODA-BOZ" manufactured by JFE Chemical Co., Ltd.; "HFB2006M" manufactured by Showa Polymer Co., Ltd.; and "Pd" and "Fa" manufactured by Shikoku Chemical Co., Ltd.

[0079] Cyanate esters are curing agents, such as bisphenol A dicyanate, polyphenol cyanate (oligomeric (3-methylene-1,5-phenyl cyanate)), 4,4'-methylene bis(2,6-dimethylphenyl cyanate), 4,4'-ethylene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanate phenyl-1-(methyl ethylidene))benzene, bis(4-cyanate phenyl) sulfide, and bis(4-cyanate phenyl) ether, etc., which are difunctional cyanate ester resins; polyfunctional cyanate ester resins derived from phenolic varnishes and cresol varnishes, etc., and some of these cyanate ester resins are triazine-modified prepolymers, etc. Specific examples of cyanate ester-based curing agents include Lonza Japan's "PT30" and "PT60" (both phenolic varnish-type multifunctional cyanate ester resins), "BA230", and "BA230S75" (a prepolymer of bisphenol A dicyanate that has been partially or completely triazed to become a trimer).

[0080] Thiol-based curing agents include, for example, trimethylolpropane trimethylolpropionate (3-mercaptopropionate), pentaerythritol tetramethylolpropionate (3-mercaptobutyrate), and trimethylolpropionate (3-mercaptopropyl)isocyanurate.

[0081] (B-3) The reactive base equivalent of the epoxy curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., even more preferably 100 g / eq. to 500 g / eq., and particularly preferably 100 g / eq. to 300 g / eq. The reactive base equivalent is the mass of the curing agent per 1 equivalent of the reactive base.

[0082] (B-3) The content (mass%) of epoxy curing agent is not particularly limited, but when the non-volatile component in the resin composition is 100% by mass, it is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less. Furthermore, the lower limit may be, for example, 0% by mass or more, 0.01% by mass or more, 0.1% by mass or more, etc.

[0083] <(C) Other Additives> The resin composition of this invention may further contain any additives as non-volatile components. Such additives include, for example, free radical polymerizable compounds such as maleimide-based free radical polymerizable compounds, vinylphenyl-based free radical polymerizable compounds, (meth)acrylic acid-based free radical polymerizable compounds, allyl-based free radical polymerizable compounds, and polybutadiene-based free radical polymerizable compounds; free radical polymerization initiators such as peroxide-based free radical polymerization initiators and azo-based free radical polymerization initiators; and polyvinyl acetal resin, polyolefin resin, polyurethane resin, polyether acetal resin, and polystyrene resin. Thermoplastic resins such as ether resins, polycarbonate resins, polyetheretherketone resins, and polyester resins; organic fillers such as rubber particles; organometallic compounds such as organocopper compounds and organozinc compounds; polymerization inhibitors such as hydroquinone, catechol, gallnutol, and phenothiazine; leveling agents such as polysiloxane-based leveling agents and acrylic polymer-based leveling agents; tackifiers such as organic bentonite and montmorillonite; defoamers such as polysiloxane-based defoamers, acrylic defoamers, fluorinated defoamers, and vinyl resin-based defoamers. Defoamers such as benzotriazole UV absorbers; adhesiveness improvers such as ureasilanes; adhesiveness enhancers such as triazole-based, tetraazole-based, and triazine-based adhesiveness enhancers; antioxidants such as hindered phenol-based and hindered amine-based antioxidants; fluorescent whitening agents such as stilbene derivatives; surfactants such as fluorine-based and polysiloxane-based surfactants; phosphorus-based flame retardants (e.g., phosphate ester compounds, azophosphorus nitrogen compounds, hypophosphorus). Flame retardants including compounds, red phosphorus, nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide); dispersants including phosphate ester dispersants, polyoxyethylene dispersants, acetylene dispersants, polysiloxane dispersants, anionic dispersants, and cationic dispersants; stabilizers including borate ester stabilizers, titanate stabilizers, aluminate stabilizers, zirconate stabilizers, isocyanate stabilizers, carboxylic acid stabilizers, and carboxylic anhydride stabilizers. (C) Other additives, which may be used alone or in combination of two or more in any ratio. (C) The content of other additives may be appropriately set by those skilled in the art.

[0084] <(D) Organic Solvents> In addition to the aforementioned non-volatile components, the resin composition of this invention may further contain any organic solvent as a volatile component. As for the (D) organic solvent, any known solvent that can dissolve at least a portion of the non-volatile components may be used, and its type is not particularly limited. Examples of the (D) 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; and 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl diethylene glycol acetate, γ-butyrolactone, and methyl methoxypropionate. Ether-ester solvents such as methyl lactate, ethyl lactate, and methyl 2-hydroxyisobutyrate; ether-alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, and diethylene glycol monobutyl ether (butyl carbitol); acetylamine solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidone; urethane solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile and propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, and methylcyclohexane; and aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, and trimethylbenzene. (D) Organic solvents may be used alone or in combination of two or more in any ratio. When using (D) organic solvents, one may be used alone or in combination of two or more in any ratio. In one embodiment, (D) the lower the content of organic solvent system, the better (e.g., when the non-volatile component in the resin composition is 100% by mass, it is 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), and preferably it is free of (0% by mass).

[0085] Properties of Resin Compositions The resin composition of this invention contains (A) magnetic powder and (B) thermosetting resin. The (A) magnetic powder comprises (A-1) ferrite powder with an average particle size of 0.8 μm or less, and (A-2) magnetic powder with an average particle size of 1.5 μm or more. The volume ratio of the magnetic powder in component (A-2) to the ferrite powder in component (A-1) ((A-2) component / (A-1) component) is 0.8 to 34.0. By using such a resin composition, a magnetic material (cured material) with excellent mechanical strength and specific permeability can be obtained.

[0086] The cured resin composition of the present invention can have excellent specific permeability (μ'). Therefore, in one embodiment, the specific permeability (μ') of the cured resin composition when measured at a measurement frequency of 100MHz and 23°C as in Test Example 1 below is preferably 5.0 or more, 6.0 or more, more preferably 7.0 or more, 8.0 or more, even more preferably 9.0 or more, 9.5 or more, and particularly preferably 10.0 or more, 10.5 or more.

[0087] The cured resin composition of the present invention can have excellent mechanical strength. Therefore, in one embodiment, the tensile breaking strength of the cured resin composition, as measured according to JIS K7127 in Test Example 2 below, is preferably 30 MPa or more, 35 MPa or more, more preferably 40 MPa or more, 45 MPa or more, even more preferably 50 MPa or more, 55 MPa or more, and particularly preferably 60 MPa or more, 62 MPa or more.

[0088] In one embodiment, when the hardened resin composition of the present invention is cut and its cross-section is observed using a scanning electron microscope (SEM), components (A-1) and (A-2) are visible in the cross-section. In another embodiment, large particles of component (A-2) are visible in the cross-section of the hardened composition, and the resin component (i.e., the hardened component other than component (A) among the non-volatile components of the resin composition) fills the gaps between the particles of component (A-2), and particles of component (A-1) are dispersed within the resin component. In this embodiment, since component (A-1) is dispersed within the resin component, there is less contact between the particles of components (A-1) and (A-2) compared to the case where magnetic powder particles are simply densely packed. In this embodiment, the mechanical strength due to the resin component is further improved.

[0089] <Manufacturing Method of Resin Composition> The resin composition of the present invention can be manufactured, for example, by adding (A) magnetic powder, (B) thermosetting resin, (C) other additives as needed, and (D) organic solvent as needed, in any mixing container in any order and / or simultaneously or partially. Furthermore, during the mixing process of adding the components, the temperature can be appropriately set, and heating and / or cooling can be performed intermittently or throughout the process. Also, stirring or agitation can be performed during the mixing process of adding the components. Furthermore, during or after addition and mixing, for example, a stirring device or agitator such as a mixer can be used to stir or agitate the resin composition to achieve uniform dispersion. Furthermore, defoaming can also be performed under low-pressure conditions such as vacuum while stirring or agitating.

[0090] [Resin Composition] When forming a magnetically hardened substrate, the resin composition can be used in the form of a paste-like resin composition at room temperature (25°C), or in the form of a resin sheet containing a layer of the resin composition.

[0091] In one embodiment, the resin composition can be made into a paste using an organic solvent, or it can be made into a paste-like resin composition without organic solvents using a liquid thermosetting resin such as a liquid epoxy resin. By reducing or eliminating the organic solvent content in the resin composition, the formation of voids caused by the evaporation of organic solvents can be suppressed, thereby resulting in a product with excellent operability and workability.

[0092] In one embodiment, the resin composition is suitable for use as a resin composition for filling through holes. Also, in one embodiment, the resin composition is suitable for use as a resin composition for forming an inductor base element in the manufacture of an inductor element.

[0093] [Resin flakes] A resin sheet comprising a support and a resin composition layer formed of the resin composition of the present invention disposed on the support.

[0094] From the perspective of thinness, the thickness of the resin composition layer is preferably 250 μm or less, and more preferably 200 μm or less. There is no particular limitation on the lower limit of the thickness of the resin composition layer, and it can usually be 5 μm or more, 10 μm or more, etc.

[0095] Examples of support materials include films made of plastic materials, metal foils, and release paper, with films and metal foils made of plastic materials being more preferred.

[0096] When using a film made of plastic material as a support, examples of plastic materials include polyesters such as polyethylene terephthalate (hereinafter referred to as "PET") and polyethylene naphthalate (hereinafter referred to as "PEN"), acrylic polymers such as polycarbonate (hereinafter referred to as "PC") and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide. Among these, polyethylene terephthalate and polyethylene naphthalate are particularly preferred, and inexpensive polyethylene terephthalate is especially preferred.

[0097] When using metal foil as a support, examples of metal foils include copper foil and aluminum foil, with copper foil being preferred. As copper foil, foil made of copper as a single metal can be used, or foil made of an alloy of copper with other metals (such as tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) can be used.

[0098] The support body, on the surface where it bonds with the resin composition layer, can also undergo matte treatment or corona treatment.

[0099] Furthermore, as a support, a support with a release layer that has a release layer on the surface bonded to the resin composition layer can also be used. The release agent used in the release layer of the support with the release layer can be, for example, one or more release agents selected from the group consisting of alkyd release agents, polyolefin release agents, carbamate release agents, and polysiloxane release agents. Commercially available products can also be used as the support for the release layer, such as PET films having a release layer mainly composed of polysiloxane or alkyd resin release agents, such as Lintec's "PET501010", "SK-1", "AL-5", and "AL-7"; Toray's "Lumirror T60"; Teijin's "Purex"; and Unitika's "Unipeel".

[0100] There is no particular limitation on the thickness of the support, but it is preferably in the range of 5μm to 75μm, and more preferably in the range of 10μm to 60μm. Furthermore, when using a support with an attached release layer, the overall thickness of the support with the release layer is preferably within the above-mentioned range.

[0101] In resin sheets, a protective film, similar to the support, can be further laminated onto the side of the resin composition layer that is not bonded to the support (i.e., the side opposite to the support). The thickness of the protective film is not particularly limited, for example, 1 μm to 40 μm. By laminating the protective film, the adhesion or scratching of dust and other contaminants on the surface of the resin composition layer can be inhibited. Resin sheets can be stored by rolling them into a roller. When a resin sheet has a protective film, it can be used by peeling off the protective film.

[0102] Resin sheets can be manufactured, for example, by coating a resin composition onto a support using a die coater or similar device to form a resin composition layer. Alternatively, an organic solvent can be mixed into the resin composition before coating onto the support, if necessary. When using an organic solvent, drying can also be performed after coating, if required.

[0103] Drying can be carried out by heating, blowing hot air, etc. There are no special limitations on the drying conditions, but the organic solvent content in the resin composition layer should be less than 10% by mass, preferably less than 5% by mass. Although it varies depending on the components contained in the resin composition, the resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

[0104] Resin sheets can be stored by rolling them into a roller. When resin sheets have a protective film, they can be used by peeling off the protective film.

[0105] [Circuit substrate and its manufacturing method] The circuit board of the present invention includes a cured resin composition. The circuit board of the first embodiment includes a substrate having through-holes and a cured resin composition of the present invention filling the through-holes. Furthermore, the circuit board of the second embodiment includes a cured layer formed by a cured resin composition layer of a resin sheet. Hereinafter, the first and second embodiments of the circuit board manufacturing method will be described. However, the manufacturing method of the circuit board of the present invention is not limited to the first and second embodiments illustrated below.

[0106] <First Implementation Form> The circuit board of the first embodiment is manufactured, for example, by a manufacturing method including the following steps (1) to (5). In the first embodiment, it is preferred to use a resin composition to form the hardened material, and more preferably to use a paste-like resin composition to form the hardened material. Includes the step of (1) filling the through-holes of a substrate having through-holes with a resin composition. (2) The step of heat-curing the resin composition to obtain a cured product. (3) Step of grinding the surface of hardened material or resin composition. (4) The steps of roughening the hardened material, and (5) The step of forming a conductor layer on the surface of the hardened material after roughening treatment. The method for manufacturing the circuit board of the present invention can be carried out in the order of steps (1) to (5), or step (2) can be carried out after step (3).

[0107] <Step (1)> Step (1) may also include the step of preparing the resin composition. The resin composition is as described above.

[0108] Furthermore, step (1) can also include, as shown in Figure 1, the preparation of a support substrate 11 and a core substrate 10 having a first metal layer 12 and a second metal layer 13 made of a metal such as copper foil disposed on both surfaces of the support substrate 11. Examples of materials for the support substrate 11 include insulating substrates such as glass epoxy boards, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. Examples of materials for the first and second metal layers include copper foil with a carrier and materials for conductor layers described later.

[0109] Alternatively, as shown in Figure 2, the process may include forming a through-hole 14 in the core substrate 10. The through-hole 14 may be formed, for example, by drilling, laser irradiation, plasma irradiation, etc. Specifically, the through-hole 14 may be formed by using a drill bit to form a through hole in the core substrate 10.

[0110] The through hole 14 can be formed using a commercially available drill bit assembly. Examples of commercially available drill bit assemblies include the Hitachi Via Mechanics "ND-1S211".

[0111] After forming the through hole 14 on the core substrate 10, as shown in FIG3, the process may include roughening the core substrate 10 and forming a plating layer 20 in the through hole 14, on the surface of the first metal layer 12, and on the surface of the second metal layer 13.

[0112] As described above, roughening treatment can be performed using either dry or wet methods. Examples of dry roughening treatment include plasma treatment. Examples of wet roughening treatment include a method that sequentially performs swelling treatment with a swelling solution, roughening treatment with an oxidizing agent, and neutralization treatment with a neutralizing solution.

[0113] The plating layer 20 is formed by plating, and the process of forming the plating layer 20 by plating is the same as the formation of the conductor layer in step (5) described later.

[0114] After preparing the core substrate 10, as shown in Figure 4, the resin composition 30a is filled into the through-hole 14. The filling can be performed, for example, by a printing method. Examples of printing methods include printing the resin composition 30a into the through-hole 14 using a squeegee, printing the resin composition 30a using a cartridge, printing the resin composition 30a by mask printing, roller coating, and inkjet printing.

[0115] <Step (2)> In step (2), after filling the through hole 14 with resin composition 30a, the resin composition 30a is thermo-cured, as shown in an example in Figure 5, forming a cured material 30 within the through hole 14. The thermo-curing conditions of the resin composition 30a vary depending on its composition or type, but the curing temperature is preferably 120°C or higher, more preferably 130°C or higher, and even more preferably 150°C or higher; preferably 245°C or lower, more preferably 220°C or lower, and even more preferably 200°C or lower. The curing time of the resin composition 30a is preferably 5 minutes or higher, more preferably 10 minutes or higher, and even more preferably 15 minutes or higher; preferably 120 minutes or lower, more preferably 110 minutes or lower, and even more preferably 100 minutes or lower.

[0116] The degree of hardening of the hardened material 30 in step (2) is preferably 80% or more, more preferably 85% or more, and even more preferably 90% or more. The degree of hardening can be measured, for example, using a differential scanning calorimeter.

[0117] Before heat curing the resin composition 30a, a preheating treatment at a temperature lower than the curing temperature may be performed on the resin composition 30a. For example, before heat curing the resin composition 30a, the resin composition 30a may be preheated at a temperature of 50°C or higher but not exceeding 120°C (preferably 60°C or higher but not exceeding 110°C, more preferably 70°C or higher but not exceeding 100°C) for a period of 5 minutes or more (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes).

[0118] <Step (3)> In step (3), as shown in one example of FIG6, excess hardened material 30 protruding from or attached to the core substrate 10 is removed by grinding to achieve planarization. The grinding method can be any method that grinds the excess hardened material 30 protruding from or attached to the core substrate 10. Examples of such grinding methods include polishing and grinding with a band. Commercially available polishing equipment includes, for example, the "NT-700IM" manufactured by Ishii Optoelectronics Co., Ltd.

[0119] The arithmetic mean roughness (Ra) of the ground surface of the hardened material 30 (after thermosetting of the hardened layer) is preferably 300 nm or more, more preferably 350 nm or more, and even more preferably 400 nm or more, from the viewpoint of improving adhesion to the plating 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.

[0120] When performing step (3) after step (2), heat treatment can also be performed as needed, with the aim of further improving the hardness of the hardened material 30, before step (3). The temperature in the aforementioned heat treatment can be based on the aforementioned hardening temperature, preferably 120°C or higher, more preferably 130°C or higher, and even more preferably 150°C or higher, preferably 245°C or lower, more preferably 220°C or lower, and even more preferably 200°C or lower. The heat treatment time is preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 15 minutes or more, preferably 90 minutes or less, more preferably 70 minutes or less, and even more preferably 60 minutes or less.

[0121] Furthermore, when step (3) is performed before step (2), a pre-heat treatment can also be performed before step (3) at a temperature lower than the curing temperature of the resin composition. The temperature in the aforementioned pre-heat treatment is preferably 100°C or higher, more preferably 110°C or higher, and even more preferably 120°C or higher, preferably 245°C or lower, more preferably 220°C or lower, and even more preferably 200°C or lower. The heat treatment time is preferably 5 minutes or higher, more preferably 10 minutes or higher, even more preferably 15 minutes or higher, preferably 90 minutes or lower, more preferably 70 minutes or lower, and even more preferably 60 minutes or lower.

[0122] <Step (4)> In step (4), the surface that has been ground in step (3) is roughened (removal of adhesive residue). There are no special limitations on the process and conditions of the roughening step, and the known process and conditions commonly used in the manufacturing method of multilayer printed circuit boards can be adopted. As a roughening step, for example, the hardened material 30 can be roughened by sequentially performing swelling treatment with swelling solution, roughening treatment with oxidant, and neutralization treatment with neutralizing solution.

[0123] There are no particular limitations on the swelling solution that can be used in the roughening step; examples include alkaline solutions and surfactant solutions, with alkaline solutions being preferred. Among alkaline solutions, sodium hydroxide solution and potassium hydroxide solution are more preferred. Commercially available swelling solutions include, for example, "Swelling Dip Securiganth P" and "Swelling Dip Securiganth SBU" manufactured by Atotech Japan.

[0124] There are no particular limitations to the swelling treatment performed with a swelling solution. For example, it can be performed by immersing the core substrate 20 containing the hardener 30 in a swelling solution at a temperature of 30°C to 90°C for 1 minute to 20 minutes. From the viewpoint of suppressing the swelling of the resin constituting the hardener 30 to a moderate level, it is preferable to immerse the hardener 30 in a swelling solution at a temperature of 40°C to 80°C for 5 minutes to 15 minutes.

[0125] The oxidizing agent used in the roughening treatment is not particularly limited; for example, an alkaline permanganate solution containing potassium permanganate or sodium permanganate dissolved in an aqueous solution of sodium hydroxide can be included. The roughening treatment using an oxidizing agent such as an alkaline permanganate solution is preferably carried out by immersing the hardened material in an oxidizing agent solution heated to 60°C to 80°C for 10 to 30 minutes. Furthermore, the concentration of permanganate in the alkaline permanganate solution is preferably 5% to 10% by mass. Commercially available oxidizing agents include, for example, alkaline permanganate solutions such as "Concentrate Compact P" and "Dosing Solution Securiganth P" manufactured by Atotech Japan.

[0126] The neutralizing solution used for neutralization treatment is preferably an acidic aqueous solution. A commercially available example is "Reduction Solution Securiganth P" manufactured by Atotech Japan. Neutralization treatment with the neutralizing solution can be performed by immersing the roughened surface treated with the oxidizing agent solution in the neutralizing solution at 30°C to 80°C for 5 to 30 minutes. From a workability point of view, it is preferable to immerse the hardened material 30, which has been roughened with the oxidizing agent solution, in a neutralizing solution at 40°C to 70°C for 5 to 20 minutes.

[0127] The arithmetic mean roughness (Ra) of the hardened material 30 after roughening treatment is preferably 300 nm or more, more preferably 350 nm or more, and even more preferably 400 nm or more, from the viewpoint of improving adhesion to the coating layer. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and even more preferably 1000 nm or less. The surface roughness (Ra) can be measured, for example, using a non-contact surface roughness gauge.

[0128] <Step (5)> In step (5), as shown in Figure 7, a conductor layer 40 is formed on the polished surface of the hardened material 30 and on the core substrate. Further, after forming the conductor layer 40, as shown in Figure 8, a portion of the conductor layer 40, the first metal layer 12, the second metal layer 13, and the plating layer 20 can be removed by etching or similar processes to form a patterned conductor layer 41. In Figure 7, the conductor layer 40 is formed on both sides of the core substrate 10, but the conductor layer 40 may also be formed on only one side of the core substrate 10.

[0129] Methods for forming the conductor layer 40 include, for example, plating, sputtering, and vapor deposition, with plating being particularly preferred. In a suitable embodiment, a patterned conductor layer 41 with the desired wiring pattern is formed by plating onto the surface of the hardened material 30 (and the plating layer 20) using appropriate methods such as semi-additive or fully additive methods. The material of the conductor layer 40 may include, for example, single metals such as gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium; or alloys of two or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. In terms of versatility, cost, and ease of graphic design, it is preferable to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or nickel-chromium alloys, copper-nickel alloys, or copper-titanium alloys; it is even better to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper, or nickel-chromium alloys; and even better to use copper.

[0130] Here, an example of an embodiment in which a patterned conductor layer 41 is formed on the surface of the polished and hardened material 30 is described in detail. A plating seed layer is formed on the surface of the polished and hardened material 30 by electroless plating. Next, an electroplated layer is formed on the formed plating seed layer by electroplating. Unwanted plating seed layers can be removed as needed by etching or other processes to form a conductor layer 40 with the desired wiring pattern. After forming the conductor layer 40, annealing can be performed as needed to improve the peel strength of the conductor layer 40. Annealing can be performed, for example, by heating the circuit board at 150-200°C for 20-90 minutes.

[0131] From the perspective of thinning, the thickness of the patterned conductor layer is preferably 70 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less, even more preferably 40 μm or less, and particularly preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The lower limit is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more.

[0132] <Second Implementation Form> The circuit board of the second embodiment includes a cured layer formed by curing a resin composition. In the second embodiment, it is preferable to use a resin sheet to form the cured layer. Hereinafter, a second embodiment of the manufacturing method of the product substrate will be described. Parts that overlap with the description of the first embodiment have been appropriately omitted.

[0133] The circuit board of the second embodiment is manufactured, for example, by a manufacturing method including the following steps (A) to (D). The steps include (A) laminating a resin sheet onto an inner substrate in a manner that bonds the resin composition layer to the inner substrate to form a hardened layer. (B) Steps for drilling holes in the hardened layer. (C) The step of roughening the surface of the hardened layer, and (D) The step of forming a conductor layer on the polished surface of the hardened layer.

[0134] The following details the steps (A) to (D) mentioned above when manufacturing the circuit board.

[0135] <Step (A)> Step (A) is a step of laminating a resin sheet onto an inner substrate in such a way that the resin composition layer is bonded to the inner substrate to form a hardened layer. As one embodiment of step (A), a resin sheet is laminated onto an inner substrate in such a way that the resin composition layer is bonded to the inner substrate, and the resin composition layer is thermally cured to form a hardened layer.

[0136] In step (A), as shown in one example of FIG9, a resin sheet 310 comprising a support 330 and a resin composition layer 320a disposed on the support 330 is laminated onto the inner layer substrate 200 in such a way that the resin composition layer 320a is bonded to the inner layer substrate 200.

[0137] The inner layer substrate 200 is an insulating substrate. The materials used for the inner layer substrate 200 may include insulating substrates such as glass epoxy boards, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The inner layer substrate 200 may also be an inner layer circuit substrate into which wiring is fabricated within its thickness.

[0138] As shown in Figure 9, the inner substrate 200 has a first conductor layer 420 disposed on a first main surface 200a and an external terminal 240 disposed on a second main surface 200b. The first conductor layer 420 may also include a plurality of wirings. In the example shown, only the wiring of the coil-shaped conductive structure 400 constituting the inductor element is shown. The external terminal 240 is a terminal for electrical connection with an external device (not shown). The external terminal 240 may be configured as part of the conductor layer disposed on the second main surface 200b.

[0139] The conductor material that can form the first conductor layer 420 and the external terminal 240 is the same as the material of the conductor layer described in the "<Step (5)>" column of the first embodiment.

[0140] The first conductor layer 420 and the external terminal 240 can be a single-layer structure or a multi-layer structure formed by laminating two or more single metal layers or alloy layers made of different kinds of metals or alloys. Furthermore, the thickness of the first conductor layer 420 and the external terminal 240 is the same as that of the second conductor layer 440 described later.

[0141] There are no particular limitations on the line (L) / gap (S) ratio of the first conductor layer 420 and the external terminal 240. From the viewpoint of reducing surface unevenness and obtaining a smooth hardened layer, it is generally 900 / 900 μm or less, preferably 700 / 700 μm or less, more preferably 500 / 500 μm or less, even more preferably 300 / 300 μm or less, and even more preferably 200 / 200 μm or less. There are no particular limitations on the lower limit of the line / gap ratio. From the viewpoint of making the resin composition layer well embedded in the gap, it is preferably 1 / 1 μm or more.

[0142] The inner layer substrate 200 may also have a plurality of through holes 220 extending from the first main surface 200a to the second main surface 200b through the inner layer substrate 200. Through holes 220a are provided in the through holes 220. Through holes 220a electrically connect the first conductor layer 420 to the external terminal 240.

[0143] The bonding between the resin composition layer 320a and the inner substrate 200 can be achieved, for example, by heating and pressing the resin sheet 310 onto the inner substrate 200 from the support 330 side. The component used to heat and press the resin sheet 310 onto the inner substrate 200 (hereinafter also referred to as the "heat-pressing component") can be, for example, a heated metal plate (stainless steel (SUS) mirror plate, etc.) or a metal roller (SUS roller). Furthermore, it is preferable to press the resin sheet 310 by means of a sheet made of an elastic material such as heat-resistant rubber, so that the resin sheet 310 fully adheres to the surface irregularities of the inner substrate 200, rather than by having the heat-pressing component directly contact the resin sheet 310 for pressing.

[0144] The temperature during heat pressing is preferably in the range of 80℃~160℃, more preferably 90℃~140℃, and even more preferably 100℃~120℃. The pressure during heat pressing is preferably in the range of 0.098MPa~1.77MPa, more preferably 0.29MPa~1.47MPa. The time during heat pressing is preferably in the range of 20 seconds~400 seconds, more preferably 30 seconds~300 seconds. The bonding between the resin sheet and the inner substrate is preferably carried out under reduced pressure conditions below 26.7 hPa.

[0145] The bonding of the resin composition layer 320a of the resin sheet 310 to the inner substrate 200 can be performed using a commercially available vacuum laminating machine. Examples of commercially available vacuum laminating machines include the vacuum pressure laminating machine manufactured by Meiki Seisakusho Co., Ltd., and the vacuum applicator manufactured by Nikko-Materials Co., Ltd.

[0146] After the resin sheet 310 is bonded to the inner substrate 200, the laminated resin sheet 310 can be smoothed by pressing it from the support 330 side under normal pressure (atmospheric pressure), for example, by pressing a heated pressing member. The pressing conditions for smoothing can be the same as the heating and pressing conditions for lamination described above. The smoothing treatment can be performed using a commercially available laminating machine. Furthermore, lamination and smoothing can also be performed continuously using the aforementioned commercially available vacuum laminating machine.

[0147] After the resin sheet 310 is laminated onto the inner substrate 200, the resin composition layer 320a is thermocured to form a hardened layer. As shown in one example of FIG10, the resin composition layer 320a bonded to the inner substrate 200 is thermocured to form the first hardened layer 320.

[0148] The thermosetting conditions for the resin composition layer 320a vary depending on the composition or type of the resin composition. The preferred curing temperature is 120°C or higher, more preferably 130°C or higher, and even more preferably 150°C or higher; the preferred temperature is 245°C or lower, more preferably 220°C or lower, and even more preferably 200°C or lower. The preferred curing time for the resin composition layer 320a is 5 minutes or higher, more preferably 10 minutes or higher, and even more preferably 15 minutes or higher; the preferred time is 120 minutes or lower, more preferably 110 minutes or lower, and even more preferably 100 minutes or lower.

[0149] The support 330 can be removed between step (A) and step (B) after the thermosetting process, or it can be peeled off after step (B).

[0150] The arithmetic mean roughness (Ra) of the hardened layer before roughening treatment is preferably 300 nm or more, more preferably 350 nm or more, and even more preferably 400 nm or more, from the viewpoint of improving adhesion to the coating 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 gauge.

[0151] In step (A), a resin composition may be used instead of a resin sheet, and applied to the inner substrate 200 using a die coater or similar device, and then thermally cured to form a cured layer.

[0152] <Step (B)> In step (B), as shown in an example of Figure 11, the first hardened layer 320 is perforated to form a via hole 360. The via hole 360 ​​serves as a path for electrically connecting the first conductor layer 420 to the second conductor layer 440 (described later). The formation of the via hole 360 ​​can be performed using tools such as drills, lasers, or plasma, depending on the composition of the resin used to form the hardened layer. The size or shape of the hole can be appropriately determined according to the design of the printed circuit board.

[0153] <Step (C)> In step (C), the surface of the hardened layer with the through holes is roughened. The roughening process in step (C) is as described in the "<Step (4)>" column of the first embodiment.

[0154] From the viewpoint of improving adhesion between the hardened layer and the plating layer, the arithmetic mean roughness (Ra) is preferably 300 nm or more, more preferably 350 nm or more, and even more preferably 400 nm or more. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and even more preferably 1000 nm or less. The surface roughness (Ra) can be measured, for example, using a non-contact surface roughness gauge.

[0155] <Step (D)> In step (D), as shown in Figure 12, a second conductor layer 440 is formed on the first hardened layer 320.

[0156] The conductor material that can form the second conductor layer 440 is the same as the conductor material described in the "<Step (5)>" column of the first embodiment.

[0157] From the viewpoint of thinning, the thickness of the second conductor layer 440 is preferably 70 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less, even more preferably 40 μm or less, and particularly preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The lower limit is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more.

[0158] The second conductor layer 440 can be formed by plating. Preferably, the second conductor layer 440 is formed by a wet plating method, such as a semi-additive method or a fully additive method, which includes an electroless plating step, a mask pattern formation step, an electrolytic plating step, and a flush etching step. By using a wet plating method to form the second conductor layer 440, it can be formed as a second conductor layer 440 containing the desired wiring pattern. Furthermore, through this step, the via wiring 360a is also formed within the via 360.

[0159] The first conductor layer 420 and the second conductor layer 440 can, for example, be configured in a spiral shape as shown in Figures 13-15 below. In one example, one end of the spiral-shaped wiring portion of the second conductor layer 440 is electrically connected to one end of the spiral-shaped wiring portion of the first conductor layer 420 via a via wiring 360a. The other end of the spiral-shaped wiring portion of the second conductor layer 440 is electrically connected to the pad 420a of the first conductor layer 42 via a via wiring 360a. Therefore, the other end of the spiral-shaped wiring portion of the second conductor layer 440 is electrically connected to the external terminal 240 via the via wiring 360a, the pad 420a, and the through-hole wiring 220a.

[0160] The coil-shaped conductive structure 400 is constructed by a spiral-shaped wiring portion of a portion of the first conductor layer 420, a spiral-shaped wiring portion of a portion of the second conductor layer 440, and a through-hole wiring 360a that electrically connects the spiral-shaped wiring portions of the first conductor layer 420 and the spiral-shaped wiring portions of the second conductor layer 440.

[0161] Following step (D), a further step of forming a hardened layer on the conductor layer may be performed. As shown in an example in Figure 14, the second hardened layer 340 is formed on the second conductor layer 440 and the first hardened layer 320 on which the via wiring 360a is formed. The second hardened layer can be formed by the same steps as those already described.

[0162] [Inductor substrate] An inductor substrate, including the circuit board of the present invention. When such an inductor substrate is a circuit board obtained by the manufacturing method of the circuit board of the first embodiment, at least a portion around the cured resin composition has an inductor pattern formed of conductors. Such an inductor substrate, for example, may be described in Japanese Patent Application Publication No. 2016-197624.

[0163] Furthermore, when the circuit board is manufactured using the method of the second embodiment, the inductor board has a hardened layer and at least a portion of a conductive structure embedded in the hardened layer. This includes the conductive structure and an inductor element formed by a portion of the hardened layer that extends along the thickness direction of the hardened layer and is surrounded by the conductive structure. Figure 13 is a schematic plan view of the inductor board containing the inductor element, viewed from its thickness direction. Figure 14 is a schematic diagram showing the cut end face of the inductor board cut at the position indicated by the lock line at point II-II shown in Figure 13. Figure 15 is a schematic plan view illustrating the structure of the first conductor layer in the inductor board.

[0164] The circuit board 100, as shown in one example of Figures 13 and 14, is an augmentation wiring board having a plurality of hardened layers (first hardened layer 320, second hardened layer 340) and a plurality of conductor layers (first conductor layer 420, second conductor layer 440), that is, having build-up hardened layers and build-up conductor layers. Furthermore, the inductor board 100 includes an inner layer board 200.

[0165] As shown in Figure 14, the first hardened layer 320 and the second hardened layer 340 constitute the magnetic portion 300, which can be viewed as a single hardened layer. Therefore, the coil-shaped conductive structure 400 is configured such that at least a portion is embedded in the magnetic portion 300. That is, in the inductor substrate 100 of this embodiment, the inductor element is constituted by the coil-shaped conductive structure 400 and a core portion of the magnetic portion 300 that extends in the thickness direction of the magnetic portion 300 and is surrounded by the coil-shaped conductive structure 400.

[0166] As shown in one example of Figure 15, the first conductor layer 420 includes a spiral-shaped wiring portion for forming a coil-shaped conductive structure 400, and a rectangular pad 420a electrically connected to the wiring 220a in the through-hole. In the example, the spiral-shaped wiring portion includes a straight portion, a right-angled curved portion, and a portion that wraps around the pad 420a. In the example, the spiral-shaped wiring portion of the first conductor layer 420 has a generally rectangular outline and has a shape that winds counterclockwise from the center side to the outside.

[0167] Similarly, a second conductor layer 440 is disposed on the first hardened layer 320. The second conductor layer 440 includes a spiral-shaped wiring portion for forming a coil-shaped conductive structure 400. In Figure 13 or Figure 14, the spiral-shaped wiring portion includes a straight portion and a curved portion that bends at right angles. In Figure 13 or Figure 14, the overall outline of the spiral-shaped wiring portion of the second conductor layer 44 is generally rectangular, and it has a clockwise winding shape from the center side outwards.

[0168] Such an inductor substrate can be used as a wiring board for mounting electronic components such as semiconductor chips, or as a (multilayer) printed wiring board using the wiring board as an inner layer substrate. Furthermore, it can be used as a chip inductor component obtained by monolithically mounting the wiring board, or as a printed wiring board obtained by surface mounting the chip inductor component.

[0169] Furthermore, this wiring board can be used to manufacture various types of semiconductor devices. Semiconductor devices including this wiring board can be suitable for use in electrical products (such as computers, mobile phones, digital cameras, and televisions) and vehicles (such as motorcycles, automobiles, trams, ships, and aircraft). [Example]

[0170] The present invention will now be specifically described by way of examples. The present invention is not limited to these examples. Furthermore, unless otherwise specified, the term "%" in the following description refers to "mass %". Also, the temperature condition unless otherwise specified is room temperature (23°C).

[0171] <Example 1> The following mixture was prepared: 30 parts by weight of nano-soft magnetic powder a (Powdertech "M001", Mn-based ferrite, average particle size 0.15μm) and 70 parts by weight of soft magnetic powder a (Epson Atmix "AW08PF3F", FeSiCr alloy (amorphous), average particle size 3μm), 3 parts by weight of liquid epoxy resin a (NIPPON STEEL Chemical & Material "ZX-1059", a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin), 3 parts by weight of liquid epoxy resin b (ADEKA "EP-4088S", glycidyl ether type aliphatic epoxy resin), and 3 parts by weight of liquid epoxy resin c. 1 part by weight of (Mitsubishi Chemical Corporation's "630", glycidyl ether type aromatic epoxy resin, made) and 1 part by weight of epoxy curing accelerator (Shikoku Kasei Corporation's "2MZA-PW", imidazole curing accelerator) are uniformly dispersed in a high-speed rotary mixer to prepare the resin composition.

[0172] <Example 2> 70 parts by weight of Microsoft magnetic powder b (manufactured by DOWA Electronics, Fe-50%Ni alloy, average particle size 3μm) were used to replace 70 parts by weight of Microsoft magnetic powder a (manufactured by Epson Atmix, "AW08PF3F"), otherwise the resin composition was prepared in the same manner as in Example 1.

[0173] <Example 3> 70 parts by weight of Microsoft magnetic powder c (MZ05 manufactured by Powdertech, MnZn ferrite, average particle size 3μm) were used to replace 70 parts by weight of Microsoft magnetic powder a (AW08PF3F manufactured by Epson Atmix). Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0174] <Example 4> The amount of nano-soft magnetic powder a (manufactured by Powdertech, "M001") was changed from 30 parts by weight to 5 parts by weight, and the amount of soft magnetic powder a (manufactured by Epson Atmix, "AW08PF3F") was changed from 70 parts by weight to 95 parts by weight. Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0175] <Example 5> The amount of nano-soft magnetic powder a (manufactured by Powdertech, "M001") was changed from 30 parts by weight to 40 parts by weight, and the amount of soft magnetic powder a (manufactured by Epson Atmix, "AW08PF3F") was changed from 70 parts by weight to 60 parts by weight. Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0176] <Example 6> 30 parts by weight of nano-soft magnetic powder b (MZ001 manufactured by Powdertech, MnZn ferrite, average particle size 0.15 μm) were used to replace 30 parts by weight of nano-soft magnetic powder a (M001 manufactured by Powdertech). Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0177] <Example 7> 30 parts by weight of nano-soft magnetic powder c (NZ001 manufactured by Powdertech, NiZn-based ferrite, average particle size 0.15 μm) were used to replace 30 parts by weight of nano-soft magnetic powder a (M001 manufactured by Powdertech). Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0178] <Example 8> 30 parts by weight of nano-soft magnetic powder d (Powdertech "E001", MnMgSr ferrite, average particle size 0.15μm) were used to replace 30 parts by weight of nano-soft magnetic powder a (Powdertech "M001"). Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0179] <Comparative Example 1> Instead of using nano-soft magnetic powder a (manufactured by Powdertech, "M001"), the amount of soft magnetic powder a (manufactured by Epson Atmix, "AW08PF3F") was changed from 70 parts by weight to 100 parts by weight. Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0180] <Comparative Example 2> Instead of using nano-soft magnetic powder a (manufactured by Powdertech, "M001"), 100 parts by weight of soft magnetic powder b (manufactured by DOWA Electronics, Fe-50%Ni alloy, average particle size 3μm) were used to replace 70 parts by weight of soft magnetic powder a (manufactured by Epson Atmix, "AW08PF3F"). Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0181] <Comparative Example 3> Instead of using nano-soft magnetic powder a (manufactured by Powdertech, "M001"), 100 parts by weight of soft magnetic powder c (manufactured by Powdertech, "MZ05") were used to replace 70 parts by weight of soft magnetic powder a (manufactured by Epson Atmix, "AW08PF3F"). Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0182] <Comparative Example 4> The amount of nano-soft magnetic powder a (manufactured by Powdertech, "M001") was changed from 30 parts by weight to 2 parts by weight, and the amount of soft magnetic powder a (manufactured by Epson Atmix, "AW08PF3F") was changed from 70 parts by weight to 98 parts by weight. Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0183] <Comparative Example 5> The amount of nano-soft magnetic powder a (manufactured by Powdertech, "M001") was changed from 30 parts by weight to 50 parts by weight, and the amount of soft magnetic powder a (manufactured by Epson Atmix, "AW08PF3F") was changed from 70 parts by weight to 50 parts by weight. Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0184] <Comparative Example 6> 30 parts by weight of other soft magnetic powder a (Epson Atmix "AW08PF1F", FeSi alloy, average particle size 1μm) were used to replace 30 parts by weight of nano soft magnetic powder a (Powdertech "M001"), otherwise the resin composition was prepared in the same manner as in Example 1.

[0185] <Comparative Example 7> 70 parts by weight of Microsoft magnetic powder c (MZ05 manufactured by Powdertech, MnZn ferrite, average particle size 3μm) were used to replace 70 parts by weight of Microsoft magnetic powder a (AW08PF3F manufactured by Epson Atmix), and 30 parts by weight of other soft magnetic powder b (MZ03S manufactured by Powdertech, MnZn ferrite, average particle size 1μm) were used to replace 30 parts by weight of nano soft magnetic powder a (M001 manufactured by Powdertech). Otherwise, the resin composition was prepared in the same manner as in Example 1.

[0186] <Experimental Example 1: Determination of Specific Permeability> A polyethylene terephthalate (PET) film (Lintec "PET501010", 50 μm thick) treated with a polysiloxane-based release agent was prepared as a support. The resin composition obtained in the examples and comparative examples was uniformly coated onto the release surface of the PET film using a doctor blade, with the dried resin composition layer thickness being 100 μm, to obtain a resin sheet. The obtained resin sheet was heated at 180°C for 90 minutes to thermocure the resin composition layer. The hardened sheet was then peeled off from the support to obtain a sheet-like product. The hardened product was cut into ring-shaped test pieces with an outer diameter of 19 mm and an inner diameter of 9 mm, serving as evaluation samples. The specific permeability (μ') of the evaluation sample was measured at room temperature (23°C) using a Keysight Technologies "16454A E4991B" at a measurement frequency of 100 MHz.

[0187] <Experimental Example 2: Determination of Tensile Fracture Point Strength> The hardened sheet obtained in Example 1 was cut into dumbbell-shaped pieces (No. 1) to obtain test specimens. The tensile strength of these specimens was determined using an ORIENTEC RTC-1250A tensile testing machine, and the breaking strength at 23°C was calculated. The determination was performed according to JIS K7127. This operation was performed three times, and the average values ​​are shown in the table.

[0188] The non-volatile components and their contents of the resin compositions in the examples and comparative examples, as well as the determination results of the test examples, are shown in Table 1 below.

[0189]

[0190] As can be seen from the above, by using a resin composition containing (A) magnetic powder and (B) thermosetting resin, wherein (A) component includes (A-1) ferrite powder with an average particle size of less than 0.8 μm and (A-2) magnetic powder with an average particle size of more than 1.5 μm, and the volume ratio of (A-2) component to (A-1) component ((A-2) component / (A-1) component) is 0.8 to 34.0, a magnetic material with excellent mechanical strength and specific permeability can be obtained.

[0191] 10: Core substrate 11:Support substrate 12: First metal layer 13: Second metal layer 14: Through hole 20: Plating layer 30a: Resin composition 30: Hardened material 40: Conductor layer 41: Patterned Conductor Layer 100: Circuit board 200: Inner layer substrate 200a: First primary surface 200b: Second Main Surface 220: Through hole 220a: Wiring inside through-hole 240:External terminal 300: Magnetic Section 310: Resin film 320a: Resin composition layer 320: First hardened layer 330: Support body 340: Second hardened layer 360: Through-hole 360a: Wiring inside the via 400: Coil-shaped conductive structure 420: First conductor layer 420a: solder pad 440: Second conductor layer

Claims

1. A resin composition comprising (A) magnetic powder and (B) thermosetting resin, wherein the (A) component comprises (A-1) ferrite powder with an average particle size of 0.8 μm or less and (A-2) magnetic powder with an average particle size of 1.5 μm or more, wherein when the non-volatile component in the resin composition is 100% by mass, the content of the (A) component is 50% by mass or more and 97% by mass or less, and when the non-volatile component in the resin composition is 100% by mass, the content of the (B) component is 0.1% by mass or more and 50% by mass or less, and the volume ratio of the (A-2) component to the (A-1) component ((A-2) component / (A-1) component) is 0.8 to 5.

0.

2. The resin composition of claim 1, wherein the average particle size of component (A-2) is 10.0 μm or less.

3. The resin composition of claim 1, wherein the average particle size of component (A-2) is 2.5 μm or more.

4. The resin composition of claim 1, wherein the average particle size of component (A-1) is 0.1 μm or more.

5. The resin composition of claim 1, wherein the average particle size of component (A-1) is less than 0.3 μm.

6. The resin composition of claim 1, wherein the ratio of the average particle size of component (A-2) to the average particle size of component (A-1) (component (A-2) / component (A-1)) is 10 or more.

7. The resin composition of claim 1, wherein component (A-1) comprises ferrite powder containing at least one element selected from Mn, Zn, Mg, Sr and Ni in addition to Fe.

8. The resin composition of claim 1, wherein component (A-2) comprises magnetic alloy powder.

9. The resin composition of claim 1, wherein when the non-volatile components in the resin composition are 100% by volume, the content of component (A) is 50% by volume or more.

10. The resin composition of claim 1, wherein when the non-volatile components in the resin composition are 100% by volume, the content of component (A) is 80% by volume or less.

11. The resin composition of claim 1, wherein component (B) comprises (B-1) epoxy resin.

12. The resin composition of claim 1, wherein the tensile breaking strength of the hardened resin composition, as determined according to JIS K7127, is 60 MPa or more.

13. The specific permeability (μ') of the hardened resin composition of the resin composition, when measured at a measurement frequency of 100 MHz and at 23 °C, is 10.0 or higher.

14. A cured product of a resin composition as claimed in any one of claims 1 to 13.

15. A resin sheet comprising a support and a resin composition layer disposed on the support, formed of a resin composition of any one of claims 1 to 13.

16. A circuit board comprising a substrate having through holes and a cured form of a resin composition of any one of claims 1 to 13 filling the through holes.

17. An inductor substrate comprising a circuit board as claimed in claim 16.

18. A circuit board comprising a cured layer of a cured resin composition as claimed in any one of claims 1 to 13.

19. An inductor substrate comprising a circuit board as claimed in claim 18.

Images