Resin composition

Abstract

The present invention addresses the problem of providing a resin composition with which it is possible to obtain a cured product having improved relative permeability and magnetic loss. The solution of the present invention is a resin composition containing (A) an iron alloy-based magnetic powder containing Ni, (B) a ferrite-based magnetic powder containing Mn, and (C) a thermosetting resin, the component (A) containing an Fe-Ni-Cr-based alloy magnetic powder, the component (B) containing or not containing a Zn-containing magnetic powder, and the component (C) containing a thermosetting resin. The mass ratio ((Mn + Zn) / Fe) of the amount of Mn and Zn to the amount of Fe in the entire magnetic powder contained in the component (A) and the component (B) is 0.055-0.16.

Description

Technical Field

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

[0002] As a core material of an inductor component, a cured product obtained by curing a resin composition containing magnetic powder is sometimes used. As the magnetic powder, FeNi alloy powder (Patent Document 1) is sometimes used.

[0003] Prior Art Documents Patent Documents Patent Document 1: Japanese Patent Application Laid-Open No. 2018-178254 Summary of the Invention

[0004] Problems to be Solved by the Invention Conventionally, an independent inductor component is usually mounted on a substrate of a semiconductor device. However, in recent years, a method of forming a coil using a conductor pattern of a substrate and disposing an inductor element inside the substrate is sometimes implemented. In order to further improve the performance of the inductor element for such uses, improvement of the magnetic properties of the core material is required. Specifically, a technique for realizing a core material having a high relative magnetic permeability and low magnetic loss using a cured product of a resin composition containing magnetic powder is needed.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide: a resin composition capable of obtaining a cured product with improved relative magnetic permeability and magnetic loss; a cured product of the resin composition; a magnetic paste and a resin sheet containing the resin composition; and a circuit board and an inductor substrate containing the cured product of the resin composition.

[0006] Means for Solving the Technical Problem The inventors of the present invention conducted in-depth research to solve the above problems. As a result, the inventors found that the following resin composition can solve the above problems: the resin composition contains in combination (A) a Ni-containing ferroalloy-based magnetic powder, (B) a Mn-containing ferrite-based magnetic powder, and (C) a thermosetting resin; the component (A) contains an Fe-Ni-Cr-based alloy magnetic powder, the component (B) contains or does not contain a Zn-containing ferrite-based magnetic powder, and the mass ratio of the total amount of Mn and Zn in the magnetic powders contained in the components (A) and (B) to the amount of Fe satisfies a specific numerical range, thereby completing the present invention.

[0007] That is, the present invention includes the following. <1>A resin composition comprising (A) a ferromagnetic powder of an Fe alloy system containing Ni, (B) a ferromagnetic powder of an Fe oxide system containing Mn, and (C) a thermosetting resin, wherein Component (A) contains an Fe-Ni-Cr alloy ferromagnetic powder, Component (B) may or may not contain a ferromagnetic powder of an Fe oxide system containing Zn, The mass ratio ((Mn + Zn) / Fe) of the total amount of Mn and Zn in the ferromagnetic powders contained in Components (A) and (B) to the amount of Fe is 0.055 or more and 0.16 or less. <2>The resin composition according to <1>, wherein Component (B) has an average particle size (D 50 ) smaller than that of Component (A). <3>The resin composition according to <1> or <2>, wherein Component (C) contains (C-1) an epoxy resin. <4>The resin composition according to any one of <1> to <3>, wherein Component (C) contains (C-2) a curing agent. <5>The resin composition according to any one of <1> to <4>, further comprising (E) a thermoplastic resin. <6>The resin composition according to any one of <1> to <5>, further comprising (F) a curing accelerator. <7>The resin composition according to any one of <1> to <6>, further comprising (G) a dispersant. <8>The resin composition according to any one of <1> to <7>, wherein the content of Ni contained in Component (A) is 33% by mass or more and 65% by mass or less relative to 100% by mass of Component (A). <9>The resin composition according to any one of <1> to <8>, wherein the content of Mn contained in Component (B) is 5% by mass or more and 35% by mass or less relative to 100% by mass of Component (B). <10>The resin composition according to any one of <1> to <9>, wherein the amount of Component (A) is 30% by volume or more relative to 100% by volume of the non-volatile components in the resin composition. <11>The resin composition according to any one of <1> to <10>, wherein the amount of Component (A) is 40% by mass or more relative to 100% by mass of the non-volatile components in the resin composition. <12>The resin composition according to any one of <1> to <11>, wherein the amount of Component (B) is 10% by volume or more relative to 100% by volume of the non-volatile components in the resin composition. <13>The resin composition according to any one of <1> to <12>, wherein the amount of component (B) is 10% by mass or more relative to 100% by mass of the non-volatile components in the resin composition. <14>The resin composition according to any one of <1> to <13>, wherein the total amount of component (A) and component (B) is 60% by volume or more relative to 100% by volume of the non-volatile components in the resin composition. <15>The resin composition according to any one of <1> to <14>, wherein the total amount of component (A) and component (B) is 70% by mass or more relative to 100% by mass of the non-volatile components in the resin composition. <16>The resin composition according to any one of <1> to <15>, which is used for filling holes. <17>The cured product of the resin composition according to any one of <1> to <16>. <18>A magnetic paste, which contains the resin composition according to any one of <1> to <16>. <19>A resin sheet, which has a support and a resin composition layer provided on the support, and the resin composition layer contains the resin composition according to any one of <1> to <16>. <20>A circuit board, which has: a board having holes, and a cured product of the resin composition according to any one of <1> to <16> filled in the holes. <21>A circuit board, which has a cured product layer containing the cured product of the resin composition according to any one of <1> to <16>. <22>An inductor board, which has the circuit board described in <21>. Effects of the Invention

[0008] According to the present invention, it is possible to provide: a resin composition capable of obtaining a cured product with improved relative magnetic permeability and magnetic loss; a cured product of the resin composition; a magnetic paste and a resin sheet containing the resin composition; and a circuit board and an inductor board containing the cured product of the resin composition. Description of the Drawings

[0009] Figure 1 is a cross-sectional view schematically showing a core board prepared in the manufacturing method of a circuit board according to a first example of an embodiment of the present invention. Figure 2 is a cross-sectional view schematically showing a core board with through holes formed in the manufacturing method of a circuit board according to a first example of an embodiment of the present invention. Figure 3It is a cross-sectional view of a core substrate with a plating layer formed in a through hole, schematically showing a method for manufacturing a circuit board according to a first example of an embodiment of the present invention. Figure 4 It is a cross-sectional view schematically showing a state in which a resin composition is filled in a through hole of a core substrate, in a method for manufacturing a circuit board according to a first example of an embodiment of the present invention. Figure 5 It is a schematic cross-sectional view for explaining step (2) of a method for manufacturing a circuit board according to a first example of an embodiment of the present invention. Figure 6 It is a schematic cross-sectional view for explaining step (3) of a method for manufacturing a circuit board according to a first example of an embodiment of the present invention. Figure 7 It is a schematic cross-sectional view for explaining step (5) of a method for manufacturing a circuit board according to a first example of an embodiment of the present invention. Figure 8 It is a schematic cross-sectional view for explaining step (5) of a method for manufacturing a circuit board according to a first example of an embodiment of the present invention. Figure 9 It is a schematic cross-sectional view for explaining step (i) in a method for manufacturing a circuit board according to a second example of an embodiment of the present invention. Figure 10 It is a schematic cross-sectional view for explaining step (i) in a method for manufacturing a circuit board according to a second example of an embodiment of the present invention. Figure 11 It is a schematic cross-sectional view for explaining step (ii) in a method for manufacturing a circuit board according to a second example of an embodiment of the present invention. Figure 12 It is a schematic cross-sectional view for explaining step (iv) in a method for manufacturing a circuit board according to a second example of an embodiment of the present invention. Figure 13 It is a schematic top view of a circuit board included in an inductor substrate, observed from one side in the thickness direction. Figure 14 It shows in Figure 13 A schematic diagram of a cut end face of a circuit board cut at the position indicated by the II-II dotted line shown. Figure 15 It is a schematic top view for explaining the constitution of a first conductor layer of a circuit board included in an inductor substrate. Detailed Description of the Invention

[0010] Hereinafter, embodiments and examples will be shown to describe the present invention in detail. However, the present invention is not limited to the following embodiments and examples, and can be implemented with any changes without departing from the scope of the claims of the present invention and its equivalent scope.

[0011] In the following description, the "non-volatile component" of the resin composition means the component obtained by removing the solvent from each component contained in the resin composition. In addition, the "resin component" of the resin composition means the component obtained by removing inorganic particles such as magnetic powder from the non-volatile components contained in the resin composition.

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

[0013] [Resin Composition] The resin composition of the present invention is a resin composition containing (A) a magnetic powder of an iron alloy system containing Ni, (B) a magnetic powder of a ferrite system containing Mn, and (C) a thermosetting resin, wherein the component (A) contains an Fe-Ni-Cr alloy magnetic powder, and the component (B) contains or does not contain a ferrite system magnetic powder containing Zn. The mass ratio ((Mn + Zn) / Fe) of the total amount of Mn and Zn in the magnetic powders contained in the components (A) and (B) to the amount of Fe is 0.055 or more and 0.16 or less. According to the resin composition, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be improved. Specifically, the relative magnetic permeability of the cured product can be increased, and the magnetic loss can be reduced.

[0014] According to the resin composition of the present invention, a cured product with improved relative magnetic permeability and magnetic loss can be obtained. The cured product of the resin composition of the present invention has a higher magnetic permeability and lower magnetic loss than the cured product of a conventional resin composition that does not satisfy the relationship that the mass ratio ((Mn + Zn) / Fe) of the total amount of Mn and Zn in the magnetic powders contained in the components (A) and (B) to the amount of Fe is 0.055 or more and 0.16 or less.

[0015] The cured product of a resin composition containing a magnetic powder of an iron alloy system containing Ni (even an Fe-Ni-Cr alloy magnetic powder) can generally have a high relative magnetic permeability. On the other hand, it has a tendency to have a large magnetic loss. Therefore, it has been difficult to obtain a cured product with a high relative magnetic permeability and a small magnetic loss. In view of such a conventional situation, the effect of the above resin composition that can improve both the relative magnetic permeability and the magnetic loss is industrially beneficial.

[0016] In the resin composition of the present invention, when the component (B) does not contain "a Zn-containing ferrite-based magnetic powder", in the above-mentioned "mass ratio of the total amount of Mn and Zn to the amount of Fe in the magnetic powders contained in the component (A) and the component (B) ((Mn + Zn) / Fe)", the content of Zn can be 0. Therefore, regarding the mode in which the component (B) does not contain "a Zn-containing ferrite-based magnetic powder", the resin composition of the present invention is characterized in that the mass ratio of the amount of Mn to the amount of Fe in the magnetic powders contained in the component (A) and the component (B) (Mn / Fe) is 0.055 or more and 0.16 or less.

[0017] Hereinafter, each component contained in the resin composition will be described in detail.

[0018] <(A) Ni-containing ferroalloy-based magnetic powder> The resin composition contains (A) a Ni-containing ferroalloy-based magnetic powder as the component (A). In addition, the component (A) contains an Fe-Ni-Cr-based alloy magnetic powder. The (A) Ni-containing ferroalloy-based magnetic powder may be used alone as one kind, or two or more kinds may be used in combination.

[0019] In addition to the Fe-Ni-Cr-based alloy magnetic powder, the component (A) may further contain a ferroalloy-based magnetic powder containing "Fe and Ni" and "any element other than Cr". Therefore, for the (A) Ni-containing ferroalloy-based magnetic powder, in addition to the Fe-Ni-Cr-based alloy magnetic powder, it may contain ferroalloy-based magnetic powders such as Fe-Ni-Si-based alloy magnetic powder, Fe-Ni-B-based alloy magnetic powder, Fe-Ni-Mo-based alloy magnetic powder, Fe-Ni-Si-Cr-based alloy magnetic powder, and Fe-Ni-Mo-Cu-based alloy magnetic powder. It should be noted that in this specification, a term such as "E1-E2-based alloy magnetic powder" means an alloy magnetic powder containing element E1 and element E2, and a term such as "E1-E2-E3-based alloy magnetic powder" means an alloy magnetic powder containing elements E1, E2, and E3. The same applies to alloy magnetic powders containing four or more elements.

[0020] As an arbitrary element that can be contained in the component (A), an element derived from an impurity inevitably mixed in according to the manufacturing method of the component (A) can also be cited, for example. Specific examples of the element derived from an inevitably mixed impurity include P, S, Mn, Mo, Cu, and Co. However, from the viewpoint of significantly exerting the effects of the present invention, the amount of the element derived from the impurity contained in the component (A) is preferably less than 1% by mass with respect to 100% by mass of the component (A).

[0021] In a preferred embodiment, the component (A) contains one or more magnetic powders selected from Fe-Ni-Cr series alloy magnetic powders and Fe-Ni-Si-Cr series alloy magnetic powders.

[0022] The amount of each element contained in the component (A) can be measured by an inductively coupled plasma optical emission spectrometer (for example, "ICP-OES 720ES" manufactured by Agilent Technologies, Inc.).

[0023] The amount of Fe contained in the component (A) is preferably 33% by mass or more, more preferably 38% by mass or more, further preferably 43% by mass or more or 48% by mass or more, and preferably 65% by mass or less, more preferably 60% by mass or less, further preferably 55% by mass or less or 53% by mass or less, based on 100% by mass of the component (A). When the amount of Fe is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0024] The amount of Ni contained in the component (A) is preferably 33% by mass or more, more preferably 38% by mass or more, further preferably 42% by mass or more or 44% by mass or more, and preferably 65% by mass or less, more preferably 60% by mass or less, further preferably 52% by mass or less or 48% by mass or less, based on 100% by mass of the component (A). When the amount of Ni is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

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

[0026] The mass ratio of the amount of Fe to the amount of Ni (Fe / Ni) contained in the component (A) is preferably 0.5 or more, more preferably 0.7 or more, further preferably 1 or more, and preferably 1.21 or less, more preferably 1.19 or less, further preferably 1.17 or less. When the ratio of the amount of Fe to the amount of Ni (Fe / Ni) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0027] The amount of Cr contained in component (A) is preferably 1% by mass or more, more preferably 1.5% by mass or more, still more preferably 1.8% by mass or more, preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3.5% by mass or less, even more preferably 3% by mass or less, 2.5% by mass or less, or 2% by mass or less, based on 100% by mass of component (A). When the amount of Cr is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0028] The mass ratio (Ni / Cr) of the amount of Ni to the amount of Cr contained in component (A) is preferably 10 or more, more preferably 13 or more, still more preferably 15 or more, even more preferably 18 or more, further preferably 20 or more, 21 or more, 22 or more, or 23 or more, and preferably 50 or less, more preferably 40 or less, still more preferably 30 or less. When the ratio of the amount of Ni to the amount of Cr (Ni / Cr) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0029] When component (A) contains Fe-Ni-Si-Cr alloy magnetic powder, the amount of Si contained in the Fe-Ni-Si-Cr alloy magnetic powder is preferably less than 1% by mass, more preferably 0.9% by mass or less, still more preferably 0.8% by mass or less, or 0.7% by mass or less, based on 100% by mass of component (A). The lower limit of the amount of Si is not particularly limited and can be, for example, 0.1% by mass or more.

[0030] (A) The average particle size (D 50 ) is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more. When the average particle size (D 50 ) of component (A) is the above lower limit value or more, it is preferable from the viewpoint of the safety of handling component (A). Further, when the average particle size (D 50 ) of component (A) is the above lower limit value or more, since the "magnetic powder containing component (A) and component (B)" and the "resin component containing component (C) thermosetting resin" can be mixed with high uniformity, the non-uniformity of component (A) and component (B) due to aggregation can be effectively suppressed. Therefore, the relative magnetic permeability and magnetic loss of the cured product can be effectively improved. The upper limit of the average particle size (D 50 ) of component (A) is preferably 10 μm or less, more preferably 8 μm or less, still more preferably 7 μm or less. The average particle size (D 50When it is below the above upper limit value, the particles of the component (A) can be smaller particles. Therefore, the generation of large eddy current loss caused by huge particles can be suppressed, and thus the magnetic loss can be effectively suppressed. This effect is particularly effective when the amount of the component (A) is large.

[0031] Unless otherwise specified, the average particle diameter (D 50 ) of the component (A) represents the median particle diameter (median diameter) based on volume. This average particle diameter (D 50 ) can be measured by the laser diffraction / scattering method based on Mie scattering theory. Specifically, a particle size distribution can be made based on volume by a laser diffraction scattering type particle size distribution measuring device, and the median particle diameter thereof can be used as the average particle diameter (D 50 ) for measurement. As the measurement sample, a sample obtained by dispersing the powder in water by ultrasonic waves can be preferably used. As the laser diffraction scattering type particle size distribution measuring device, "LA-500" manufactured by Horiba, Ltd., "SALD-2200" manufactured by Shimadzu Corporation, etc. can be used.

[0032] The specific surface area of the component (A) is preferably 0.05 m 2 / g or more, more preferably 0.1 m 2 / g or more, further preferably 0.5 m 2 / g or more, preferably 20 m 2 / g or less, more preferably 10 m 2 / g or less, further preferably 5 m 2 / g or less. When the specific surface area of the component (A) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved. The specific surface area of the magnetic powder can be measured by the BET method. Specifically, the specific surface area can be measured by using a specific surface area measuring device ("Macsorb HM Model 1210" manufactured by Mountech Co., Ltd.) according to the BET method to adsorb nitrogen on the surface of the sample and using the BET multi-point method.

[0033] The particles of the component (A) are preferably spherical or ellipsoidal particles. The value obtained by dividing the length of the major axis of the particles of the component (A) by the length of the minor axis (aspect ratio) is preferably 2 or less, more preferably 1.6 or less, and further preferably 1.4 or less. When the aspect ratio of the component (A) is within the above range, the magnetic loss can be suppressed or the viscosity of the resin composition can be reduced.

[0034] The true density of the component (A) can be, for example, in the range of 4 g / cm 3 to 10 g / cm 3 .

[0035] (A) There is no limitation on the manufacturing method of the component. For example, the component (A) can be manufactured by an atomization method. In this atomization method, the component (A) is usually obtained by a method including dropping a bath solution (molten metal) containing molten iron and nickel while blowing high-pressure water or gas to cause rapid condensation and solidification. In the above atomization method, a water atomization method of blowing water into the dropping bath solution is preferred. As such an atomization method, for example, the method described in Japanese Patent Application Laid-Open No. 2018-178254 can be adopted.

[0036] The content (volume %) of the component (A) contained in the resin composition, based on 100 volume % of the total of the components (A) to (C), is preferably 30 volume % or more, more preferably 40 volume % or more, further preferably 45 volume % or more, 47 volume % or more, or 48 volume % or more, and preferably 70 volume % or less, more preferably 65 volume % or less, further preferably 60 volume % or less, or 58 volume % or less. When the content of the component (A) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved. In addition, when the content of the component (A) is below the upper limit value of the above range, the viscosity of the resin composition can be effectively reduced, and it is easy to form a paste.

[0037] The content (volume %) of each component contained in the resin composition on a volume basis is calculated from the mass of the components contained in the resin composition. Specifically, the volume of each component can be obtained by dividing the mass by the specific gravity, and then the content (volume %) on a volume basis can be calculated based on the volume of each component obtained.

[0038] The content (mass %) of the component (A) contained in the resin composition, based on 100 mass % of the total of the components (A) to (C), is preferably 40 mass % or more, more preferably 50 mass % or more, further preferably 55 mass % or more, and preferably 90 mass % or less, more preferably 85 mass % or less, further preferably 80 mass % or less. When the content of the component (A) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved. In addition, when the content of the component (A) is below the upper limit value of the above range, the viscosity of the resin composition can be effectively reduced, and it is easy to form a paste.

[0039] When the resin composition contains components other than the components (A) to (C), the content (volume %) of the component (A) contained in the resin composition is preferably 30% by volume or more, more preferably 35% by volume or more, further preferably 40% by volume or more or 42% by volume or more, preferably 70% by volume or less, more preferably 60% by volume or less, and further preferably 55% by volume or less, based on 100% by volume of the non-volatile components contained in the resin composition. When the content of the component (A) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved. In addition, when the content of the component (A) is below the upper limit value of the above range, the viscosity of the resin composition can be effectively reduced, and it is easy to form a paste.

[0040] When the resin composition contains components other than the components (A) to (C), the content (mass %) of the component (A) contained in the resin composition is preferably 40% by mass or more, more preferably 50% by mass or more, further preferably 60% by mass or more, preferably 85% by mass or less, more preferably 80% by mass or less, and further preferably 75% by mass or less, based on 100% by mass of the non-volatile components contained in the resin composition. When the content of the component (A) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved. In addition, when the content of the component (A) is below the upper limit value of the above range, the viscosity of the resin composition can be effectively reduced, and it is easy to form a paste.

[0041] <(B) Mn-containing ferrite-based magnetic powder> The resin composition contains (B) a Mn-containing ferrite-based magnetic powder as the component (B). In addition, the component (B) may or may not contain a Zn-containing ferrite-based magnetic powder. The Mn-containing ferrite-based magnetic powder can be used alone or in combination of two or more.

[0042] Ferrite-based magnetic powders are generally formed of composite oxides mainly composed of iron oxide and are chemically stable. Therefore, by using ferrite-based magnetic powders, advantages such as high corrosion resistance, low fire hazard, and low demagnetization tendency can be obtained.

[0043] Examples of the component (B) include Mn-based ferrite powder, Mn-Zn-based ferrite powder, Fe-Mn-based ferrite powder, Mn-Mg-based ferrite powder, Mn-Mg-Sr-based ferrite powder, and the like. It should be noted that in this specification, a term such as "E1-based ferrite powder" means a ferrite powder containing the element E1, a term such as "E1-E2-based ferrite powder" means a ferrite powder containing the elements E1 and E2, and a term such as "E1-E2-E3-based ferrite powder" means a ferrite powder containing the elements E1, E2, and E3. The same applies to ferrite powders containing four or more elements. It should be noted that when the elements such as element E1 and element E2 in the ferrite powder contain Fe, the Fe is not trivalent iron from iron oxide (Fe2O3), but divalent iron.

[0044] (B) component is preferably one or more ferrite powders selected from Mn-based ferrite powder and Mn-Zn-based ferrite powder. When the range of the preferred (B) component is regarded as the (B-1) component, regarding the mass ratio ((Mn + Zn) / Fe) of the total amount of Mn and Zn to the amount of Fe in the total magnetic powder contained in the (A) component and the (B) component, the amounts of Mn and Zn are more preferably from the (B-1) component. That is, more preferably, the mass ratio ((Mn + Zn) / Fe) of the total amount of Mn and Zn to the amount of Fe in the total magnetic powder contained in the (A) component and the (B-1) component is 0.055 or more and 0.16 or less.

[0045] The amount of Fe contained in the (B) component, relative to 100% by mass of the (B) component, is preferably 33% by mass or more, more preferably 38% by mass or more, further preferably 42% by mass or more or 43% by mass or more, preferably 70% by mass or less, more preferably 65% by mass or less, further preferably 60% by mass or less, 58% by mass or less or 57% by mass or less. When the amount of Fe is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0046] The amount of Mn contained in the (B) component, relative to 100% by mass of the (B) component, is preferably 5% by mass or more, more preferably 7% by mass or more, further preferably 10% by mass or more or 12% by mass or more, preferably 35% by mass or less, more preferably 30% by mass or less, further preferably 28% by mass or less or 26% by mass or less. When the amount of Mn is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0047] When the component (B) is a Mn-Zn ferrite powder, the amount of Zn contained in the component (B) is preferably 1% by mass or more, more preferably 3% by mass or more, still more preferably 5% by mass or more or 6% by mass or more, and preferably 15% by mass or less, more preferably 10% by mass or less, still more preferably 8% by mass or less or 7% by mass or less, based on 100% by mass of the component (B). When the amount of Zn is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0048] The total amount of Mn and Zn contained in the component (B) is preferably 5% by mass or more, more preferably 7% by mass or more, still more preferably 10% by mass or more or 12% by mass or more, and preferably 35% by mass or less, more preferably 30% by mass or less, still more preferably 28% by mass or less or 26% by mass or less, based on 100% by mass of the component (B). When the amounts of Mn and Zn contained in the component (B) are within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0049] The component (B) preferably has an average particle diameter (D 50 ) smaller than that of the magnetic powder of the Ni-containing ferroalloy system (A). When the component (B) has an average particle diameter smaller than that of the magnetic powder of the Ni-containing ferroalloy system (A), the component (B) enters the gaps between the particles of the component (A), so that high filling of the magnetic powder becomes possible, and thus, magnetic properties such as relative magnetic permeability can be improved.

[0050] The ratio of the average particle diameter (D 50 ) of the component (B) to the average particle diameter (D 50 ) of the component (A) ((D 50 ) of the component (B) / (D 50 ) of the component (A)) is preferably within a specific range. Specifically, the ratio of the average particle diameters (D 50 ) ((D 50 ) of the component (B) / (D 50 ) of the component (A)) is preferably 0.001 or more, more preferably 0.01 or more, still more preferably 0.05 or more, and preferably 0.9 or less, more preferably 0.6 or less, still more preferably 0.3 or less. When the ratio of the average particle diameters (D 50 ) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0051] The average particle diameter (D 50) The specific range is preferably 0.05 μm or more, more preferably 0.1 μm or more, further preferably 0.2 μm or more, preferably 3 μm or less, more preferably 2 μm or less, and further preferably 1.5 μm or less. When the average particle diameter (D 50 ) of component (B) is above the above lower limit value, the viscosity of the resin composition can be reduced. In addition, when it is below the upper limit value, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively made good.

[0052] (B) The average particle diameter (D 50 ) of the component can be measured by the same method as the average particle diameter (D 50 ) of component (A).

[0053] (B) The component preferably has a specific surface area larger than that of the magnetic powder of the iron alloy system containing Ni in (A). The specific range of the specific surface area of component (B) is preferably 0.1 m 2 / g or more, more preferably 1.0 m 2 / g or more, further preferably 2 m 2 / g or more, preferably 40 m 2 / g or less, more preferably 30 m 2 / g or less, and further preferably 20 m 2 / g or less.

[0054] (B) The particles of the component are preferably spherical or ellipsoidal particles. The value obtained by dividing the length of the major axis of the particles of component (B) by the length of the minor axis (aspect ratio) is preferably 2 or less, more preferably 1.5 or less, and further preferably 1.2 or less. When the aspect ratio of component (B) is within the above range, magnetic loss can be suppressed or the viscosity of the resin composition can be reduced.

[0055] (B) The true density of the component can be, for example, in the range of 4 g / cm 3 ~10 g / cm 3 .

[0056] The content (volume %) of component (B) contained in the resin composition, relative to the total 100 volume % of components (A) to (C), is preferably 15 volume % or more, more preferably 20 volume % or more, further preferably 25 volume % or more, preferably 60 volume % or less, more preferably 50 volume % or less, and further preferably 40 volume % or less or 39 volume % or less. When the content of component (B) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively made good.

[0057] The content (mass %) of component (B) contained in the resin composition is preferably 10 mass % or more, more preferably 15 mass % or more, still more preferably 20 mass % or more or 21 mass % or more, and preferably 50 mass % or less, more preferably 40 mass % or less, still more preferably 35 mass % or less or 34 mass % or less, based on 100 mass % of the total of components (A) to (C). When the content of component (B) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0058] (B) The volume ratio of component (B) to component (A) ((content of component (B) (volume %)) / (content of component (A) (volume %))) is preferably within a specific range. Specifically, the volume ratio ((content of component (B) (volume %)) / (content of component (A) (volume %))) is preferably 0.01 or more, more preferably 0.1 or more, still more preferably 0.3 or more or 0.4 or more, and preferably 2 or less, more preferably 1.5 or less, still more preferably 1 or less or 0.9 or less. When the volume ratio ((content of component (B) (volume %)) / (content of component (A) (volume %))) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0059] (B) The mass ratio of component (B) to component (A) ((content of component (B) (mass %)) / (content of component (A) (mass %))) is preferably within a specific range. Specifically, the mass ratio ((content of component (B) (mass %)) / (content of component (A) (mass %))) is preferably 0.01 or more, more preferably 0.1 or more, still more preferably 0.2 or more or 0.25 or more, and preferably 1 or less, more preferably 0.7 or less, still more preferably 0.5 or less. When the mass ratio ((content of component (B) (mass %)) / (content of component (A) (mass %))) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0060] When the resin composition contains components other than components (A) to (C), the content (volume %) of component (B) contained in the resin composition is preferably 10 volume % or more, more preferably 15 volume % or more, still more preferably 20 volume % or more, 22 volume % or more or 24 volume % or more, and preferably 50 volume % or less, more preferably 45 volume % or less, still more preferably 40 volume % or less, 38 volume % or less or 37 volume % or less, based on 100 volume % of the non-volatile components contained in the resin composition. When the content of component (B) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved. In addition, when the content of component (B) is below the upper limit value of the above range, the viscosity of the resin composition can be effectively reduced, and it is easy to form a paste.

[0061] When the resin composition contains components other than the components (A) to (C), the content (% by mass) of the component (B) contained in the resin composition is preferably 10% by mass or more, more preferably 15% by mass or more, still more preferably 20% by mass or more, preferably 45% by mass or less, more preferably 40% by mass or less, still more preferably 35% by mass or less or 34% by mass or less, based on 100% by mass of the non-volatile components contained in the resin composition. When the content of the component (B) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved. In addition, when the content of the component (B) is below the upper limit value of the above range, the viscosity of the resin composition can be effectively reduced, and it is easy to form a paste.

[0062] When the resin composition contains components other than the components (A) to (C), the total content (% by volume) of the components (A) and (B) contained in the resin composition is preferably 60% by volume or more, more preferably 70% by volume or more, still more preferably 75% by volume or more or 77% by volume or more, preferably 90% by volume or less, more preferably 85% by volume or less, still more preferably 80% by volume or less or 79% by volume or less, based on 100% by volume of the non-volatile components contained in the resin composition. When the total content of the components (A) and (B) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0063] When the resin composition contains components other than the components (A) to (C), the total content (% by mass) of the components (A) and (B) contained in the resin composition is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, 92% by mass or more or 94% by mass or more, preferably 98% by mass or less, more preferably 97% by mass or less, still more preferably 96% by mass or less, based on 100% by mass of the non-volatile components contained in the resin composition. When the total content of the components (A) and (B) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0064] <(C) Thermosetting resin> The resin composition contains a (C) thermosetting resin as the component (C). The (C) thermosetting resin can bond magnetic powders including an (A) Ni-containing ferroalloy-based magnetic powder and a (B) Mn-containing ferrite-based magnetic powder. In addition, the (C) thermosetting resin reacts by heat and generates a bond, and can be cured. Therefore, by curing a resin composition comprising an (A) Ni-containing ferroalloy-based magnetic powder, a (B) Mn-containing ferrite-based magnetic powder, and a (C) thermosetting resin, a cured product can be obtained. The cured product has excellent relative magnetic permeability and magnetic loss, and thus an excellent magnetic layer can be formed.

[0065] Examples of the (C) thermosetting resin include an epoxy resin, a phenolic resin, an active ester resin, an amine resin, an acid anhydride resin, a benzoxazine resin, a cyanate ester resin, and a carbodiimide resin. The (C) thermosetting resin can be used alone as one kind, or two or more kinds can be used in combination.

[0066] The (C) thermosetting resin preferably contains a (C-1) epoxy resin. The (C-1) epoxy resin refers to a resin having one or more epoxy groups in the molecule. When the (C) thermosetting resin contains the (C-1) epoxy resin, the dispersibility of magnetic powders such as the (A) component and the (B) component can be improved, or the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively made good.

[0067] Examples of the (C-1) epoxy resin include a xylenol type epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a bisphenol AF type epoxy resin, a dicyclopentadiene type epoxy resin, a triphenol type epoxy resin, a phenol novolac type epoxy resin, a glycidylamine type epoxy resin, a glycidyl ester type epoxy resin, a cresol novolac type epoxy resin, a biphenyl type epoxy resin, a linear aliphatic epoxy resin, an epoxy resin having a butadiene structure, an alicyclic epoxy resin, an alicyclic epoxy resin having an ester skeleton; a heterocyclic epoxy resin, an epoxy resin containing a spiro ring, a cyclohexane type epoxy resin, a cyclohexanedimethanol type epoxy resin, a trimethylol type epoxy resin; a tetraphenylethane type epoxy resin; a naphthalene ether type epoxy resin, a tert-butyl-catechol type epoxy resin, a naphthalene type epoxy resin, a naphthol type epoxy resin, an anthracene type epoxy resin, a naphthol novolac type epoxy resin and other epoxy resins containing a condensed ring skeleton, an isocyanurate type epoxy resin, an epoxy resin containing an alkyleneoxy skeleton and a butadiene skeleton, an epoxy resin containing a fluorene structure, etc. The (C-1) epoxy resin can be used alone as one kind, or two or more kinds can be used in combination.

[0068] (C-1) The epoxy resin preferably includes an epoxy resin having two or more epoxy groups in one molecule. With respect to 100% by mass of the total amount of the (C-1) epoxy resin, the proportion of the epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 70% by mass or more.

[0069] (C-1) The epoxy resin includes an epoxy resin that is liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resin") and an epoxy resin that is solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resin"). The (C-1) epoxy resin may be only a liquid epoxy resin, may be only a solid epoxy resin, or may be a combination of a liquid epoxy resin and a solid epoxy resin. Among them, the (C-1) epoxy resin preferably includes a liquid epoxy resin, and more preferably includes only a liquid epoxy resin.

[0070] As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferred. As the liquid epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, epoxy resin having a butadiene structure, epoxy resin containing an alkyleneoxy skeleton and a butadiene skeleton, epoxy resin containing a fluorene structure, dicyclopentadiene type epoxy resin are preferred. Among them, bisphenol A type epoxy resin and bisphenol F type epoxy resin are more preferred.

[0071] As specific examples of the liquid epoxy resin, there can be cited "YX7400" manufactured by Mitsubishi Chemical Corporation; "HP4032", "HP4032D", "HP4032SS" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "828US", "828EL", "825", "EPIKOTE 828EL" (bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "807", "1750" (bisphenol F-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "152" (phenol novolac-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630", "630LSD", "604" (glycidylamine-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "ED-523T" (GLYCIROL-type epoxy resin) manufactured by ADEKA Corporation; "EP-3950L", "EP-3980S" (glycidylamine-type epoxy resin) manufactured by ADEKA Corporation; "EP-4088S" (dicyclopentadiene-type epoxy resin) manufactured by ADEKA Corporation; "ZX-1059" (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin) manufactured by Nippon Steel Chemical Co., Ltd.; "EX-721" (glycidyl ester-type epoxy resin) manufactured by Nagase ChemteX Corporation; "EX-991L" (epoxy resin containing an alkyleneoxy skeleton) manufactured by Nagase ChemteX Corporation; "CELLOXIDE 2021P", "CELLOXIDE 2081" (alicyclic epoxy resin having an ester skeleton) manufactured by Daicel Corporation; "PB-3600", "JP-100", "JP-200" (epoxy resin having a butadiene structure) manufactured by Nippon Soda Co., Ltd.; "ZX1658", "ZX1658GS" (liquid 1,4-glycidylcyclohexane-type epoxy resin) manufactured by Nippon Steel Chemical Co., Ltd.; "EG-280" (epoxy resin containing a fluorene structure) manufactured by Osaka Gas Chemical Co., Ltd.; etc. The liquid epoxy resin can be used alone or in combination of two or more kinds.

[0072] As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferred, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferred. As the solid epoxy resin, xylenol-type epoxy resin, naphthalene-type epoxy resin, naphthalene-type tetrafunctional epoxy resin, cresol novolac-type epoxy resin, dicyclopentadiene-type epoxy resin, triphenol-type epoxy resin, naphthol-type epoxy resin, biphenyl-type epoxy resin, naphthyl ether-type epoxy resin, anthracene-type epoxy resin, bisphenol A-type epoxy resin, bisphenol AF-type epoxy resin, tetraphenylethane-type epoxy resin are preferred, and dicyclopentadiene-type epoxy resin is more preferred.

[0073] As specific examples of the solid epoxy resin, there can be mentioned "HP4032H" (naphthalene-type epoxy resin) manufactured by DIC Corporation; "HP-4700", "HP-4710" (naphthalene-type tetrafunctional epoxy resin) manufactured by DIC Corporation; "N-690" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "N-695" (cresol novolak-type epoxy resin) manufactured by DIC Corporation; "HP-7200", "HP-7200HH", "HP-7200H" (dicyclopentadiene-type epoxy resin) manufactured by DIC Corporation; "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthalene ether-type epoxy resin) manufactured by DIC Corporation; "EPPN-502H" (triphenol-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolak-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC3000", "NC3000L", "NC3100" (biphenyl-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V" (naphthol-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "ESN485" (naphthol novolak-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YX4000", "YL6121" (biphenyl-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX4000HK" (xylenol-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX8800" (anthracene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YX7700" (novolak-type epoxy resin containing a xylene structure) manufactured by Mitsubishi Chemical Corporation; "PG-100", "CG-500" manufactured by Osaka Gas Chemical Co., Ltd.; "YL7760" (bisphenol AF-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "YL7800" (fluorene-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "1010" (solid bisphenol A-type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "1031S" (tetraphenylethane-type epoxy resin) manufactured by Mitsubishi Chemical Corporation, etc. The solid epoxy resin can be used alone as one kind, or two or more kinds can be used in combination.

[0074] As the epoxy resin, when using a liquid epoxy resin and a solid epoxy resin in combination, the mass ratio of the liquid epoxy resin to the solid epoxy resin (liquid epoxy resin / solid epoxy resin) is preferably 0.5 or more, more preferably 1 or more, further preferably 5 or more, and still further preferably 10 or more.

[0075] (C-1) The weight-average molecular weight (Mw) of the epoxy resin is preferably 100 to 5000, more preferably 250 to 3000, and further preferably 400 to 1500. The weight-average molecular weight of the resin can be measured by gel permeation chromatography (GPC) method as a value in terms of polystyrene conversion.

[0076] The content (mass %) of the component (C-1) contained in the resin composition is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, still more preferably 1 mass % or more, preferably 10 mass % or less, more preferably 5 mass % or less, and still more preferably 3 mass % or less, based on 100 mass % of the total of (A) to (C). When the content of the (C-1) epoxy resin is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0077] When the resin composition contains components other than the components (A) to (C), the content (mass %) of the component (C-1) contained in the resin composition is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, still more preferably 1 mass % or more, preferably 10 mass % or less, more preferably 5 mass % or less, and still more preferably 3 mass % or less, based on 100 mass % of the non-volatile components contained in the resin composition. When the content of the (C-1) epoxy resin is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0078] When the resin composition contains components other than the components (A) to (C), the content (mass %) of the component (C-1) contained in the resin composition is preferably 30 mass % or more, more preferably 35 mass % or more, still more preferably 40 mass % or more, preferably 60 mass % or less, more preferably 50 mass % or less, still more preferably 45 mass % or less, 43 mass % or less, or 42 mass % or less, based on 100 mass % of the resin components contained in the resin composition. When the content of the (C-1) epoxy resin is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0079] When the (C) thermosetting resin contains the (C-1) epoxy resin, the (C) thermosetting resin may contain a resin capable of reacting and bonding with the (C-1) epoxy resin. Hereinafter, the resin capable of reacting and bonding with the (C-1) epoxy resin is sometimes referred to as “(C-2) curing agent”. Examples of the (C-2) curing agent include phenolic resins, active ester resins, amine resins, carbodiimide resins, acid anhydride resins, benzoxazine resins, cyanate ester resins, and mercaptan resins. The (C-2) curing agent may be used alone or in combination of two or more. Among them, phenolic resins are preferred.

[0080] As the phenolic resin, a resin having one or more, preferably two or more hydroxyl groups bonded to an aromatic ring such as a benzene ring or a naphthalene ring in one molecule can be used. From the viewpoints of heat resistance and water resistance, a phenolic resin having a novolak structure is preferred. Further, from the viewpoint of adhesion, a nitrogen-containing phenolic resin is preferred, and a phenolic resin containing a triazine skeleton is more preferred. Among them, from the viewpoint of highly satisfying heat resistance, water resistance and adhesion, a linear novolak resin containing a triazine skeleton is preferred.

[0081] Specific examples of the phenolic resin include, for example, "MEH-7700", "MEH-7810", "MEH-7851", "MEH-8000H" manufactured by Meiko Kasei Co., Ltd.; "NHN", "CBN", "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN-170", "SN-180", "SN-190", "SN-475", "SN-485", "SN-495", "SN-495V", "SN-375", "SN-395" manufactured by Nippon Steel Chemical & Material Co., Ltd.; "TD-2090", "TD-2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "EXB-9500", "HPC-9500", "KA-1160", "KA-1163", "KA-1165" manufactured by DIC Corporation; "GDP-6115L", "GDP-6115H", "ELPC75", etc. manufactured by Gun Ei Chemical Industry Co., Ltd.

[0082] As the active ester resin, a resin having one or more, preferably two or more active ester groups in one molecule can be used. Among them, as the active ester resin, compounds having two or more highly reactive ester groups in one molecule, such as phenolic esters, thiophenolic esters, N-hydroxyamine esters, esters of heterocyclic hydroxy compounds, etc., are preferred. This active ester resin is preferably a resin obtained by a condensation reaction of a carboxylic acid compound and / or a thiocarboxylic acid compound with a hydroxy compound and / or a thiol compound. In particular, from the viewpoint of improving heat resistance, an active ester resin obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester resin obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, pyromellitic acid, etc. Examples of the phenol compound or naphthol compound include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalin, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, pyrogallol, dicyclopentadiene-type diphenol compound, novolak resin, etc. Here, the "dicyclopentadiene-type diphenol compound" refers to a diphenol compound obtained by condensing two molecules of phenol with one molecule of dicyclopentadiene.

[0083] Preferred specific examples of the active ester resin include an active ester resin containing a dicyclopentadiene-type diphenol structure, an active ester resin containing a naphthalene structure, an active ester resin containing an acetylated product of novolak resin, and an active ester resin containing a benzoylated product of novolak resin. Among them, an active ester resin containing a naphthalene structure and an active ester resin containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" represents a divalent structural unit formed by phenylene-dicyclopentyl-phenylene.

[0084] Regarding commercially available products of active ester resins, as active ester resins containing a dicyclopentadiene-type diphenol structure, examples include "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T", "EXB-8000L-65TM" (manufactured by DIC Corporation); as active ester resins containing a naphthalene structure, examples include "EXB-9416-70BK", "EXB-8100L-65T" (manufactured by DIC Corporation); as active ester resins containing an acetylated product of a linear phenolic resin, an example is "DC808" (manufactured by Mitsubishi Chemical Corporation); as active ester resins containing a benzoylated product of a linear phenolic resin, an example is "YLH1026" (manufactured by Mitsubishi Chemical Corporation); as active ester resins that are acetylated products of linear phenolic resins, an example is "DC808" (manufactured by Mitsubishi Chemical Corporation); as active ester resins that are benzoylated products of linear phenolic resins, examples include "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), "YLH1048" (manufactured by Mitsubishi Chemical Corporation); etc.

[0085] As the amine resin, a resin having one or more, preferably two or more amino groups in one molecule can be used. As the amine resin, examples include aliphatic amines, polyetheramines, alicyclic amines, aromatic amines, etc., among which aromatic amines are preferred. The amine resin is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of the amine resin include 4,4'-methylenebis(2,6-dimethylaniline), diphenyl diaminosulfone, 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, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 3,3-dimethyl-5,5-diethyl-4,4-diphenylmethanediamine, 2,2-bis(4-aminophenyl)propane, 2,2-bis(4(4-aminophenoxy)phenyl)propane, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis(4-(4-aminophenoxy)phenyl)sulfone, bis(4-(3-aminophenoxy)phenyl)sulfone, etc. As commercially available products of the amine resin, examples include "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD A-A", "KAYAHARD A-B", "KAYAHARD A-S" manufactured by Nippon Kayaku Co., Ltd., "Epicure W" manufactured by Mitsubishi Chemical Corporation, etc.

[0086] As the carbodiimide resin, a resin having one or more, preferably two or more carbodiimide structures in one molecule can be used. Specific examples of the carbodiimide resin include: aliphatic biscarbodiimides such as tetramethylene-bis(tert-butylcarbodiimide) and cyclohexane bis(methylene-tert-butylcarbodiimide); biscarbodiimides such as phenylenebis(xylenylcarbodiimide); aliphatic polycarbodiimides such as polyhexamethylene carbodiimide, polytrimethylhexamethylene carbodiimide, polycyclohexylene carbodiimide, poly(methylenebiscyclohexylene carbodiimide), and poly(isophorone carbodiimide); aromatic polycarbodiimides such as poly(phenylenecarbodiimide), poly(naphthylenecarbodiimide), poly(tolylenecarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(diethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylphenylenecarbodiimide), poly(xylenylcarbodiimide), poly(tetramethylxylenylcarbodiimide), poly(methylenediphenylenecarbodiimide), and poly[methylenebis(methylphenylenecarbodiimide)]. Commercially available products of the carbodiimide resin include, for example, "CARBODILITE V-02B", "CARBODILITE V-03", "CARBODILITE V-04K", "CARBODILITE V-07", and "CARBODILITE V-09" manufactured by Nisshinbo Chemical Inc.; "Stabaxol P", "Stabaxol P400", "Hycasyl 510", etc. manufactured by Lanxess Corporation.

[0087] As the acid anhydride-based resin, a resin having one or more acid anhydride groups in one molecule can be used, and a resin having two or more acid anhydride groups in one molecule is preferred. Specific examples of the acid anhydride-based resin include: phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfone tetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, ethylene glycol bis(trimellitate), polymer-type acid anhydrides such as styrene-maleic resin obtained by copolymerizing styrene and maleic acid, etc. Commercially available products of the acid anhydride-based resin include, for example, "HNA-100", "MH-700", "MTA-15", "DDSA", "OSA" manufactured by Shin Nippon Rika Co., Ltd., "YH-306", "YH-307" manufactured by Mitsubishi Chemical Corporation, "HN-2200", "HN-5500" manufactured by Resonac Corporation; "EF-30", "EF-40", "EF-60", "EF-80" manufactured by Cray Valley Company, etc.

[0088] Specific examples of the benzoxazine-based resin include "JBZ-OD100D", "JBZ-OP100D", "ODA-BOZ" manufactured by JFE Chemical Corporation; "P-d", "F-a" manufactured by Shikoku Kasei Kogyo Co., Ltd.; "HFB2006M" manufactured by Showa Highpolymer Co., Ltd., etc.

[0089] Examples of the cyanate ester resin include, for example, difunctional cyanate ester resins such as bisphenol A dicyanate, polyphenol cyanate, oligomeric (3-methylmethylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylenediphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanatophenyl)propane, 1,1-bis(4-cyanatophenyl)methane, bis(4-cyanato-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatophenyl-1-(methylethylidene))benzene, bis(4-cyanatophenyl) sulfide, and bis(4-cyanatophenyl) ether; polyfunctional cyanate ester resins derived from linear phenolic resins and cresol phenolic resins; prepolymers obtained by triazine-forming a part of these cyanate ester resins; and the like. Specific examples of the cyanate ester resin include "PT30" and "PT60" (linear phenolic type polyfunctional cyanate ester resins), "ULL-950S" (polyfunctional cyanate ester resin), "BA230", and "BA230S75" (prepolymers in which a part or all of bisphenol A dicyanate is triazine-formed to form a trimer) manufactured by arxada.

[0090] Examples of the thiol resin include, for example, trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetra(3-mercaptobutyrate), tris(3-mercaptopropyl) isocyanurate, and the like.

[0091] (C-2) The active group equivalent of the curing agent is preferably 50 g / eq. to 3000 g / eq., more preferably 100 g / eq. to 1000 g / eq., still more preferably 100 g / eq. to 500 g / eq., and even more preferably 100 g / eq. to 300 g / eq. The active group equivalent represents the mass of the (C-2) curing agent per 1 equivalent of the active group.

[0092] When the number of epoxy groups of the (C-1) epoxy resin is 1, the number of active groups of the (C-2) curing agent is preferably 0.01 or more, more preferably 0.1 or more, still more preferably 0.5 or more, preferably 10 or less, more preferably 5 or less, and still more preferably 3 or less. The active group of the (C-2) curing agent is an active hydroxyl group or the like, which varies depending on the type of the curing agent. In addition, the number of epoxy groups of the (C-1) epoxy resin is the value obtained by summing up the values obtained by dividing the mass of the non-volatile component of each epoxy resin by the epoxy equivalent for all the epoxy resins. Further, the number of active groups of the (C-2) curing agent is the value obtained by summing up the values obtained by dividing the mass of the non-volatile component of each curing agent by the active group equivalent for all the curing agents.

[0093] The content (mass %) of the component (C-2) contained in the resin composition is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, still more preferably 1 mass % or more, preferably 10 mass % or less, more preferably 5 mass % or less, and still more preferably 3 mass % or less, based on 100 mass % of the total of the components (A) to (C). When the content of the (C-2) curing agent is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0094] When the resin composition contains components other than the components (A) to (C), the content (mass %) of the component (C-2) contained in the resin composition is preferably 0.1 mass % or more, more preferably 0.5 mass % or more, still more preferably 1 mass % or more, preferably 10 mass % or less, more preferably 5 mass % or less, and still more preferably 3 mass % or less, based on 100 mass % of the non-volatile components contained in the resin composition. When the content of the (C-2) curing agent is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0095] When the resin composition contains components other than the components (A) to (C), the content (mass %) of the component (C-2) contained in the resin composition is preferably 15 mass % or more, more preferably 20 mass % or more, still more preferably 25 mass % or more or 27 mass % or more, preferably 40 mass % or less, more preferably 35 mass % or less, and still more preferably 30 mass % or less or 29 mass % or less, based on 100 mass % of the resin components contained in the resin composition. When the content of the (C-2) curing agent is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0096] The range of the weight-average molecular weight (Mw) of the (C) thermosetting resin can generally be the same as the range of the weight-average molecular weight of the above (C-1) epoxy resin.

[0097] The content (mass %) of the component (C) contained in the resin composition is preferably 0.1 mass % or more, more preferably 1 mass % or more, still more preferably 3 mass % or more, preferably 10 mass % or less, more preferably 7 mass % or less, and still more preferably 5 mass % or less, based on 100 mass % of the total of the non-volatile components in the components (A) to (C). When the content of the (C) thermosetting resin is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0098] When the resin composition contains components other than the components (A) to (C), the content (mass%) of the component (C) contained in the resin composition is preferably 0.1 mass% or more, more preferably 1 mass% or more, still more preferably 2 mass% or more or 2.5 mass% or more, preferably 10 mass% or less, more preferably 7 mass% or less, and still more preferably 5 mass% or less, based on 100 mass% of the non-volatile components contained in the resin composition. When the content of the (C) thermosetting resin is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0099] When the resin composition contains components other than the components (A) to (C), the content (mass%) of the component (C) contained in the resin composition is preferably 50 mass% or more, more preferably 60 mass% or more, still more preferably 65 mass% or more or 68 mass% or more, preferably 80 mass% or less, more preferably 75 mass% or less, and still more preferably 70 mass% or less, based on 100 mass% of the resin components contained in the resin composition. When the content of the (C) thermosetting resin is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0100] <(D) Optional magnetic powder (magnetic powder other than component (A) and component (B))> The resin composition may further contain, as an optional component, (D) a magnetic powder other than component (A) and component (B) in combination with the above components (A) to (C). The "(D) magnetic powder other than component (A) and component (B)" as the component (D) is sometimes appropriately referred to as "(D) optional magnetic powder".

[0101] As the (D) optional magnetic powder, particles of a material having a relative magnetic permeability greater than 1 can be used. The material of the (D) optional magnetic powder is usually an inorganic material, and can be a soft magnetic material or a hard magnetic material. In addition, the material of the (D) optional magnetic powder can be used alone or in combination of two or more. Therefore, the (D) optional magnetic powder can be a soft magnetic powder, a hard magnetic powder, or a combination of a soft magnetic powder and a hard magnetic powder. In addition, the (D) optional magnetic powder can be used alone or in combination of two or more. Among them, the (D) optional magnetic powder preferably contains a soft magnetic powder, and more preferably contains only a soft magnetic powder.

[0102] Examples of the (D) optional magnetic powder include magnetic metal oxide powder and magnetic metal powder.

[0103] Examples of the magnetic metal oxide powder include, for example, ferrite-based magnetic powders; and iron oxide powders such as iron(III) oxide powder and iron(II,III) oxide powder; and the like.

[0104] Examples of the ferrite-based magnetic powders include, for example, Mg-Zn ferrite powders, Mg-Sr ferrite powders, Cu-Zn 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, and the like.

[0105] Examples of the magnetic metal powders include, for example, pure iron powders; crystalline or amorphous alloy magnetic powders such as Fe-Si alloy powders, Fe-Si-Al alloy powders, Fe-Cr alloy powders, Fe-Cr-Si alloy powders, Fe-Cr-Al alloy powders, Fe-Co alloy powders, and Co-based amorphous alloy powders; non-crystalline alloy materials such as Co-based amorphous; and the like.

[0106] When the resin composition contains an arbitrary magnetic powder (D), based on 100% by volume of the non-volatile components of the resin composition, the content (% by volume) of the component (D) contained in the resin composition is preferably 20% by volume or less, more preferably 10% by volume or less, still more preferably 5% by volume or less, and even more preferably 3% by volume or less. The lower limit of the content (% by volume) of the component (D) may be 0% by volume or may exceed 0% by volume. Among them, the lower limit of the content (% by volume) of the component (D) is preferably 0% by volume. When the content (% by volume) of the arbitrary magnetic powder (D) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0107] When the resin composition contains an arbitrary magnetic powder (D), based on 100% by mass of the non-volatile components of the resin composition, the amount (% by mass) of the arbitrary magnetic powder (D) contained in the resin composition is preferably 30% by mass or less, more preferably 15% by mass or less, still more preferably 7.5% by mass or less, and even more preferably 5% by mass or less. The lower limit of the content (% by mass) of the component (D) may be 0% by mass or may exceed 0% by mass. Among them, the lower limit of the content (% by mass) of the component (D) is preferably 0% by mass. When the content (% by mass) of the arbitrary magnetic powder (D) is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0108] <(E) Thermoplastic resin> In the resin composition, (E) a thermoplastic resin can be further included as an optional component in combination with the above components (A) to (D). The (E) thermoplastic resin as the component (E) does not contain substances belonging to the above components (A) to (D). By using the (E) thermoplastic resin, the mechanical properties of the cured product of the resin composition can be effectively improved.

[0109] Examples of the (E) thermoplastic resin include, for example, phenoxy resin, polyimide resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, polyetheretherketone resin, polyester resin, etc. The (E) thermoplastic resin can be used alone as one kind, or two or more kinds can be used in combination.

[0110] Examples of the phenoxy resin include, for example, phenoxy resins having one or more skeletons selected from bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenol acetophenone skeleton, phenolic aldehyde skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal of the phenoxy resin can be any functional group such as phenolic hydroxyl group, epoxy group, etc. Specific examples of the phenoxy resin include: "1256" and "4250" (both are phenoxy resins containing bisphenol A skeleton) manufactured by Mitsubishi Chemical Corporation; "YX8100" (phenoxy resin containing bisphenol S skeleton) manufactured by Mitsubishi Chemical Corporation; "YX6954" (phenoxy resin containing bisphenol acetophenone skeleton) manufactured by Mitsubishi Chemical Corporation; "FX280" and "FX293" manufactured by Nippon Steel Chemical Materials Co., Ltd.; "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", "YL7482", and "YL7891BH30" manufactured by Mitsubishi Chemical Corporation; etc.

[0111] Specific examples of the polyimide resin include "SLK-6100" manufactured by Shin-Etsu Chemical Co., Ltd., "RIKACOAT SN20" and "RIKACOAT PN20" manufactured by Shin Nippon Rika Co., Ltd., etc. Specific examples of the polyimide resin also include linear polyimide obtained by reacting bifunctional hydroxyl-terminated polybutadiene, diisocyanate compound, and tetracarboxylic dianhydride (the polyimide described in Japanese Patent Laid-Open No. 2006-37083), modified polyimide such as polyimide containing a polysiloxane skeleton (the polyimide described in Japanese Patent Laid-Open Nos. 2002-12667 and 2000-319386, etc.).

[0112] Examples of the polyvinyl acetal resin include, for example, polyvinyl formal resin and polyvinyl butyral resin, and polyvinyl butyral resin is preferred. Specific examples of the polyvinyl acetal resin include the S-LEC BH series, BX series (e.g., BX-5Z), KS series (e.g., KS-1), BL series, BM series, etc. manufactured by Sekisui Chemical Co., Ltd.

[0113] Examples of the polyolefin resin include, for example, ethylene-based copolymer resins such as low-density polyethylene, ultra-low-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, and ethylene-methyl acrylate copolymer; polyolefin-based polymers such as polypropylene and ethylene-propylene block copolymer.

[0114] Examples of the polybutadiene resin include, for example, resins containing a hydrogenated polybutadiene skeleton, polybutadiene resins containing a hydroxyl group, polybutadiene resins containing a phenolic hydroxyl group, polybutadiene resins containing a carboxyl group, polybutadiene resins containing an acid anhydride group, polybutadiene resins containing an epoxy group, polybutadiene resins containing an isocyanate group, polybutadiene resins containing a urethane group, polyphenylene ether-polybutadiene resins, etc.

[0115] Specific examples of the polyamideimide resin include "VYLOMAX HR11NN" and "VYLOMAX HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of the polyamideimide resin also include modified polyamideimides such as "KS9100" and "KS9300" (polyamideimide containing a polysiloxane skeleton) manufactured by Hitachi Chemical Co., Ltd.

[0116] Specific examples of the polyethersulfone resin include "PES5003P" etc. manufactured by Sumitomo Chemical Co., Ltd.

[0117] Specific examples of the polysulfone resin include polysulfones "P1700", "P3500", etc. manufactured by Solvay Specialty Polymers.

[0118] Specific examples of the polyphenylene ether resin include "NORYL SA90" etc. manufactured by SABIC. Specific examples of the polyetherimide resin include "Ultem" etc. manufactured by GE.

[0119] Examples of the polycarbonate resin include a carbonate resin containing a hydroxyl group, a carbonate resin containing a phenolic hydroxyl group, a carbonate resin containing a carboxyl group, a carbonate resin containing an acid anhydride group, a carbonate resin containing an isocyanate group, a carbonate resin containing a urethane group, etc. Specific examples of the polycarbonate resin include "FPC0220" manufactured by Mitsubishi Gas Chemical Company, "T6002", "T6001" (polycarbonate diol) manufactured by Asahi Kasei Chemicals Corporation, "C-1090", "C-2090", "C-3090" (polycarbonate diol) manufactured by Kuraray Co., Ltd., etc. Specific examples of the polyetheretherketone resin include "Sumiploy K" manufactured by Sumitomo Chemical Company, etc.

[0120] Examples of the polyester resin include polyethylene terephthalate resin, polyethylene naphthalate resin, polybutylene terephthalate resin, polybutylene naphthalate resin, polypropylene terephthalate resin, polypropylene naphthalate resin, polycyclohexanedimethylene terephthalate resin, etc.

[0121] (E) The weight average molecular weight (Mw) of the thermoplastic resin is preferably greater than 5000, more preferably 8000 or more, still more preferably 10000 or more, and even more preferably 20000 or more. There is no particular limitation on the upper limit, and it may be, for example, 1 million or less, 500,000 or less, 100,000 or less, etc.

[0122] When the resin composition contains (E) the thermoplastic resin, with respect to 100% by mass of the non-volatile components of the resin composition, the content (% by mass) of the (E) component contained in the resin composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 1% by mass or less. When the amount of the (E) thermoplastic resin is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0123] When the resin composition contains (E) the thermoplastic resin, with respect to 100% by mass of the resin components of the resin composition, the content (% by mass) of the (E) component contained in the resin composition is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, preferably 25% by mass or less, more preferably 20% by mass or less, and still more preferably 15% by mass or less. When the amount of the (E) thermoplastic resin is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0124] <(F) Curing accelerator> In the resin composition, (F) a curing accelerator can be further contained as an optional component in combination with the above components (A) to (E). The (F) curing accelerator as the component (F) does not contain substances belonging to the above components (A) to (E). Since the (F) curing accelerator functions as a catalyst for the reaction of the (B) thermosetting resin, it can promote the curing of the resin composition.

[0125] Examples of the (F) curing accelerator include an imidazole-based curing accelerator, a phosphorus-based curing accelerator, an amine-based curing accelerator, a guanidine-based curing accelerator, a metal-based curing accelerator, a urea-based curing accelerator, and the like. The (F) curing accelerator can be used alone or in combination of two or more. Among them, as the (F) curing accelerator, an imidazole-based curing accelerator and a phosphorus-based curing accelerator are preferred, and an imidazole-based curing accelerator is more preferred.

[0126] As imidazole-based curing accelerators, examples include: 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline and other imidazole compounds, as well as adducts of imidazole compounds and epoxy resins. 2-Ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole are preferred. As imidazole-based curing accelerators, commercially available products can be used, examples include "P200-H50" manufactured by Mitsubishi Chemical Corporation; "CUREZOL 2MZ", "2E4MZ", "Cl1Z", "Cl1Z-CN", "Cl1Z-CNS", "C11Z-A", "2MZ-OK", "2MA-OK", "2MA-OK-PW", "2MZA-PW", "2PHZ", "2PHZ-PW", "1B2PZ", "1B2PZ-10M", etc. manufactured by Shikoku Kasei Kogyo Co., Ltd.

[0127] Phosphorus-based curing accelerators include, for example, phosphonium salts and phosphines. Phosphonium salts include, for example, aliphatic phosphonium salts such as tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, tetrabutylphosphonium decanoate, tetrabutylphosphonium laurate, n-butylphosphonium tetraphenylborate, bis(tetrabutylphosphonium)pyromellitic acid salt, tetrabutylphosphonium hexahydrophthalate, tetrabutylphosphonium 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenolate, and di-tert-butylmethylphosphonium tetraphenylborate; methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, and propyltriphenylphosphonium bromide. phosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, p-tolyltriphenylphosphonium tetra-p-tolylborate, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetra-p-tolylborate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate and the like aromatic phosphonium salts.

[0128] Examples of the phosphine include aliphatic phosphines such as tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(2-butenyl)phosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, and tricyclohexylphosphine; dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tri(4-ethylphenyl)phosphine, tri(4-propylphenyl)phosphine, tri(4-isopropylphenyl)phosphine, tri(4-butylphenyl)phosphine, tri(4-tert-butylphenyl)phosphine, tri(2,4-dimethylphenyl)phosphine, tri(2,5-dimethylphenyl)phosphine, tri(2,6-dimethylphenyl)phosphine, tri( Aromatic phosphines such as tri(3,5-dimethylphenyl)phosphine, tri(2,4,6-trimethylphenyl)phosphine, tri(2,6-dimethyl-4-ethoxyphenyl)phosphine, tri(2-methoxyphenyl)phosphine, tri(4-methoxyphenyl)phosphine, tri(4-ethoxyphenyl)phosphine, tri(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, 1,2-bis(diphenylphosphino)acetylene, and 2,2'-bis(diphenylphosphino)diphenyl ether; aromatic phosphine-borane complexes such as triphenylphosphine-triphenylborane; aromatic phosphine-quinone addition reactants such as triphenylphosphine-p-benzoquinone addition reactants, etc.

[0129] As the phosphorus-based curing accelerator, a commercially available item can be used, and examples thereof include "TBP-DA" manufactured by Hokko Chemical Industry Co., Ltd. and the like.

[0130] As amine-based curing accelerators, examples include trialkylamines such as triethylamine and tributylamine; 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, 1,8-diazabicyclo[5,4,0]undecene-7, 4-dimethylaminopyridine, 2,4,6-tris(dimethylaminomethyl)phenol, etc., and 4-dimethylaminopyridine is preferred. As amine-based curing accelerators, commercially available products can be used, and examples include "PN-50", "PN-23", "MY-25", etc. manufactured by Ajinomoto Fine-Techno Co., Ltd.

[0131] As guanidine-based curing accelerators, examples include: dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, 1-(o-tolyl)biguanide, etc., and dicyandiamide and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred.

[0132] As metal-based curing accelerators, examples 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 cobalt(II) acetylacetonate and cobalt(III) acetylacetonate; organocopper complexes such as copper(II) acetylacetonate; organozinc complexes such as zinc(II) acetylacetonate; organoiron complexes such as iron(III) acetylacetonate; organonickel complexes such as nickel(II) acetylacetonate; organomanganese complexes such as manganese(II) acetylacetonate, etc. As organometallic salts, examples include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, zinc stearate, etc.

[0133] Examples of the urea-based curing accelerator include: 1,1-dimethylurea; aliphatic dimethylureas such as 1,1,3-trimethylurea, 3-ethyl-1,1-dimethylurea, 3-cyclohexyl-1,1-dimethylurea, and 3-cyclooctyl-1,1-dimethylurea; aromatic dimethylureas such as 3-phenyl-1,1-dimethylurea, 3-(4-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea, 3-(2-methylphenyl)-1,1-dimethylurea, 3-(4-methylphenyl)-1,1-dimethylurea, 3-(3,4-dimethylphenyl)-1,1-dimethylurea, 3-(4-isopropylphenyl)-1,1-dimethylurea, 3-(4-methoxyphenyl)-1,1-dimethylurea, 3-(4-nitrophenyl)-1,1-dimethylurea, 3-[4-(4-methoxyphenoxy)phenyl]-1,1-dimethylurea, 3-[4-(4-chlorophenoxy)phenyl]-1,1-dimethylurea, 3-[3-(trifluoromethyl)phenyl]-1,1-dimethylurea, N,N-(1,4-phenylene)bis(N’,N’-dimethylurea), and N,N-(4-methyl-1,3-phenylene)bis(N’,N’-dimethylurea) [toluene bisdimethylurea].

[0134] When the resin composition contains the (F) curing accelerator, the content (mass%) of the (F) component contained in the resin composition is preferably 0.001 mass% or more, more preferably 0.005 mass% or more, still more preferably 0.01 mass% or more, preferably 2 mass% or less, more preferably 1 mass% or less, and still more preferably 0.1 mass% or less, based on 100 mass% of the non-volatile components of the resin composition. When the content of the (F) curing accelerator is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0135] When the resin composition contains the (F) curing accelerator, the content (mass%) of the (F) component contained in the resin composition is preferably 0.01 mass% or more, more preferably 0.10 mass% or more, still more preferably 0.20 mass% or more, preferably 3 mass% or less, more preferably 1 mass% or less, and still more preferably 0.5 mass% or less, based on 100 mass% of the resin components of the resin composition. When the content of the (F) curing accelerator is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0136] <(G) Dispersant> In the resin composition, (G) a dispersant can be further contained as an optional component in combination with the above components (A) to (F). The (G) dispersant as the component (G) does not contain substances belonging to the above components (A) to (F). By using the (G) dispersant, the dispersibility of magnetic powders including (A) an Ni-containing ferroalloy-based magnetic powder and (B) an Mn-containing ferrite-based magnetic powder (furthermore, (D) an arbitrary magnetic powder) can be improved.

[0137] There is no limitation on the type of the (G) dispersant. For example, as the (G) dispersant, a dispersant containing a functional group having an adsorption ability for magnetic powders and causing the magnetic powders to be dispersed by repulsion between the (G) dispersants (such as electrostatic repulsion, steric repulsion, etc.) when adsorbed to the magnetic powders can be used. As such a (G) dispersant, for example, an acidic dispersant, a basic dispersant, etc. can be cited.

[0138] Acidic dispersants usually contain acidic functional groups such as carboxyl groups, sulfo groups (-SO3H), sulfuric acid groups (-OSO3H), phosphonyl groups (-PO(OH)2), phosphonyloxy groups (-OPO(OH)2), hydroxyphosphonyl groups (-PO(OH)-), thioalkyl groups (-SH), etc. The acidic functional groups usually have dissociable protons and can be neutralized by bases such as amines and hydroxide ions. As preferred acidic dispersants, for example, acidic polymer dispersants containing polymer chains such as polyoxyalkylene chains and polyether chains can be cited. As preferred examples of acidic dispersants, “C-2093I” and “SC-1015F (a multifunctional comb-shaped functional polymer having an ionic group in the main chain and a polyoxyalkylene chain in the graft chain)” manufactured by NOF Corporation; “ED152”, “ED153”, “ED154”, “ED118”, “ED174”, “ED251”, “DA-375” (polyether type phosphate ester-based dispersants) manufactured by Kusumoto Chemical Co., Ltd.; “RS-410”, “RS-610”, “RS-710” (pH is 1.9) (phosphate ester-based dispersants) of the “PHOSPHANOL” series manufactured by Toho Chemical Industry Co., Ltd.; “AKM-0531”, “AFB-1521”, “SC-0505K”, “SC-0708A” of the “MALIALIM” series manufactured by NOF Corporation.

[0139] Basic dispersants usually contain basic functional groups such as primary, secondary, and tertiary amino groups; ammonium groups; imino groups; and nitrogen-containing heterocyclic groups such as pyridine, pyrimidine, pyrazine, imidazole, and triazole. The basic functional groups can be neutralized by acids such as organic acids and inorganic acids. As preferred basic dispersants, for example, basic polymer dispersants containing polymer chains such as polyester chains can be cited. As a preferred example of a basic dispersant, “PB-881” (a polyamine-based dispersant containing a polyester chain) manufactured by Ajinomoto Fine-Techno Co., Inc. can be cited.

[0140] (G) The dispersant can be used alone as one kind or in combination of two or more kinds.

[0141] When the resin composition contains the (G) dispersant, based on 100% by mass of the non-volatile components of the resin composition, the content (% by mass) of the (G) component contained in the resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, further preferably 0.5% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, and further preferably 1% by mass or less. When the content of the (G) dispersant is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0142] When the resin composition contains the (G) dispersant, based on 100% by mass of the resin component of the resin composition, the content (% by mass) of the (G) component contained in the resin composition is preferably 5% by mass or more, more preferably 10% by mass or more, further preferably 15% by mass or more, preferably 30% by mass or less, more preferably 25% by mass or less, and further preferably 20% by mass or less. When the content of the (G) dispersant is within the above range, the relative magnetic permeability and magnetic loss of the cured product of the resin composition can be effectively improved.

[0143] <(H) Optional additive> The resin composition may further contain (H) an optional additive as an optional component in combination with the above components (A) to (G). The (H) optional additive of the (H) component does not include substances belonging to the above components (A) to (G).

[0144] As optional additives (H), examples thereof include: radical polymerizable compounds such as maleimide-based radical polymerizable compounds, vinylphenyl-based radical polymerizable compounds, (meth)acrylic acid-based radical polymerizable compounds, allyl-based radical polymerizable compounds, and polybutadiene-based radical polymerizable compounds; radical polymerization initiators such as peroxide-based radical polymerization initiators and azo-based radical polymerization initiators; inorganic filler materials such as silica particles; organic filler materials such as rubber particles; organometallic compounds such as organic copper compounds and organic zinc compounds; polymerization inhibitors such as hydroquinone, catechol, pyrogallol, and phenothiazine; leveling agents such as silicone-based leveling agents and acrylic polymer-based leveling agents; thickeners such as Benton and montmorillonite; antifoaming agents such as silicone-based antifoaming agents, acrylic-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents; ultraviolet absorbers such as benzotriazole-based ultraviolet absorbers; adhesion improvers such as ureasilane; adhesion imparting agents such as triazole-based adhesion imparting agents, tetrazole-based adhesion imparting agents, and triazine-based adhesion imparting agents; antioxidants such as hindered phenol-based antioxidants; flame retardants such as phosphorus-based flame retardants (e.g., phosphate compounds, phosphazene compounds, phosphinic acid compounds, red phosphorus), nitrogen-based flame retardants (e.g., melamine sulfate), halogen-based flame retardants, and inorganic flame retardants (e.g., antimony trioxide); stabilizers such as borate-based stabilizers, titanate-based stabilizers, aluminate-based stabilizers, zirconate-based stabilizers, isocyanate-based stabilizers, carboxylic acid-based stabilizers, and carboxylic anhydride-based stabilizers, etc. Optional additives (H) can be used alone as one kind, or two or more kinds can be used in combination.

[0145] <(I) Solvent> The resin composition can further contain (I) solvent as a volatile component in combination with non-volatile components such as the above components (A) to (H).

[0146] As (I) solvent, organic solvents are usually used. Examples of the solvent include: ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, isopentyl acetate, methyl propionate, ethyl propionate, and γ-butyrolactone; tetrahydropyran, tetrahydrofuran, 1,4-di Ether solvents such as alkanes, diethyl ether, diisopropyl ether, dibutyl ether, diphenyl ether; alcohol solvents such as methanol, ethanol, propanol, butanol, ethylene glycol; ether ester solvents such as 2-ethoxyethyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethyldiglycol acetate, γ-butyrolactone, methyl methoxypropionate; ester alcohol solvents such as methyl lactate, ethyl lactate, methyl 2-hydroxyisobutyrate; ether alcohol solvents such as 2-methoxypropanol, 2-methoxyethanol, 2-ethoxyethanol, propylene glycol monomethyl ether, diethylene glycol monobutyl ether (butyl carbitol); amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone; sulfoxide solvents such as dimethyl sulfoxide; nitrile solvents such as acetonitrile, propionitrile; aliphatic hydrocarbon solvents such as hexane, cyclopentane, cyclohexane, methylcyclohexane; aromatic hydrocarbon solvents such as benzene, toluene, xylene, ethylbenzene, trimethylbenzene, etc. (I) The solvent can be used alone or in combination of two or more.

[0147] (I) The content of the solvent is preferably set to adjust the melt viscosity of the resin composition to an appropriate range. The content of (I) the solvent, based on 100% by mass of the non-volatile components in the resin composition, can be, for example, 3% by mass or less, 1% by mass or less, 0.5% by mass or less, 0.1% by mass or less, 0.01% by mass or less. When the content of (I) the solvent contained in the resin composition is small, the generation of voids caused by the volatilization of (I) the solvent can be suppressed, and thus the processability and operability of the resin composition can be improved.

[0148] [Properties and Uses of Resin Composition] The above resin composition can be cured by heat. Therefore, by thermally curing the resin composition, a cured product of the resin composition can be obtained. Generally, among the components contained in the resin composition, volatile components such as (I) the solvent can be volatilized by the heat during thermal curing, while non-volatile components such as components (A) to (H) are not volatilized by the heat during thermal curing. Therefore, the cured product of the resin composition can contain the non-volatile components of the resin composition or their reaction products.

[0149] Therefore, according to the above resin composition, a cured product having a high relative magnetic permeability can be obtained. For example, when measuring the relative magnetic permeability of a cured product obtained by thermally curing the resin composition at 190 °C for 90 minutes under the conditions of a measurement frequency of 20 MHz and a room temperature of 23 °C, the relative magnetic permeability is preferably 23 or more, more preferably 23.5 or more, and further preferably 23.7 or more. There is no particular limitation on the upper limit of the relative magnetic permeability, and it can be, for example, 35 or less or 30 or less, etc. The relative magnetic permeability of the cured product can be measured by the method described in the examples below.

[0150] In addition, according to the above resin composition, a cured product having low magnetic loss can be obtained. The magnetic loss can be represented by the loss factor tanδ. Generally, the smaller the loss factor tanδ, the smaller the magnetic loss. For example, when measuring the loss factor tanδ of a cured product obtained by thermally curing the resin composition at 190°C for 90 minutes under the conditions of a measurement frequency of 20 MHz and a room temperature of 23°C, the loss factor tanδ is preferably 0.04 or less, more preferably 0.035 or less, and still more preferably 0.033 or less. There is no particular limitation on the lower limit of the loss factor. For example, it can be 0.00001 or more, etc. The loss factor tanδ of the cured product can be measured by the method described in the examples below.

[0151] There is no particular limitation on the properties of the resin composition. Therefore, the resin composition can be in a solid state or in a paste state with fluidity. For example, the resin composition can be made into a paste-like resin composition using a solvent, or can be made into a paste-like resin composition by using a liquid thermosetting resin such as liquid epoxy resin. When the solvent content in the resin composition is low, the generation of holes due to the volatilization of the solvent can be suppressed, and thus the processability and operability can also be excellent.

[0152] Utilizing the above excellent properties, the resin composition is preferably used as a resin composition for manufacturing inductors. For example, the above resin composition is preferably used as a resin composition for hole filling for filling the holes of a substrate provided on a circuit board. In addition, for example, the above resin composition is also preferably used for forming a cured product layer on a circuit board. To be easily applied to these uses, the resin composition can be used in a paste form or in the form of a resin sheet including a layer of the resin composition.

[0153] [Manufacturing method of resin composition] The resin composition can be manufactured, for example, by mixing the above components. The above components can be mixed partially or entirely simultaneously, or can be mixed sequentially. During the process of mixing each component, the temperature can be appropriately set, so heating and / or cooling can be performed temporarily or continuously. In addition, during the process of mixing each component, stirring or oscillation can be performed. Furthermore, defoaming can be performed under low-pressure conditions such as under vacuum.

[0154] [Magnetic paste] The magnetic paste of the present invention contains the above resin composition. Since the magnetic paste is generally a fluid paste containing a resin composition, it can be preferably used for filling holes by a printing method. The magnetic paste can contain only the above resin composition, or can contain any components in combination with the resin composition. Preferably, the paste-like resin composition itself can be used as the magnetic paste.

[0155] The magnetic paste is preferably in a paste state at 23°C. The viscosity of the magnetic paste is preferably 20 Pa·s or more, more preferably 25 Pa·s or more, further preferably 30 Pa·s or more, still further preferably 50 Pa·s or more, preferably 200 Pa·s or less, more preferably 180 Pa·s or less, and further preferably 160 Pa·s or less at 23°C. The viscosity can be measured, for example, using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., "RE-80U", 3°×R9.7 rotor) under the measurement conditions of a sample amount of 0.22 ml and a rotation speed of 5 rpm.

[0156] [Resin sheet] The resin sheet of the present invention includes a support and a resin composition layer provided on the support. The resin composition layer contains the above resin composition and preferably contains only the resin composition.

[0157] From the viewpoint of thinning, the thickness of the resin composition layer is preferably 250 μm or less, more preferably 200 μm or less. The lower limit of the thickness of the resin composition layer can be, for example, 5 μm or more, 10 μm or more, etc.

[0158] Examples of the support include a film of a plastic material, a metal foil, and a release paper, and preferably a film or a metal foil formed of a plastic material.

[0159] When a film of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes simply referred to as "PET") and polyethylene naphthalate (hereinafter sometimes simply referred to as "PEN"); polycarbonate (hereinafter sometimes simply referred to as "PC"); acrylic polymers such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyethersulfide (PES), polyether ketone, polyimide, etc. Among them, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0160] When a metal foil is used as the support, examples of the metal foil include a copper foil and an aluminum foil. Among them, a copper foil is preferred. As the copper foil, a foil formed of single metal copper or a foil formed of an alloy of copper and other metals (such as tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) can be used.

[0161] For the support, a matting treatment or a corona treatment can be performed on the surface that is joined to the resin composition layer.

[0162] In addition, as the support, a support with a release layer can be used, which has a release layer on the surface joined to the resin composition layer. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from alkyd-based release agents, polyolefin-based release agents, polyurethane-based release agents, and silicone-based release agents. As the support with a release layer, commercially available products can be used. Examples include PET films having a release layer mainly composed of a silicone-based release agent or an alkyd resin-based release agent, such as "PET501010", "SK-1", "AL-5", "AL-7" manufactured by Lintec Corporation; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; "Unipeel" manufactured by Unitika Ltd., etc.

[0163] The thickness of the support is not particularly limited, and preferably ranges from 5 μm to 75 μm, more preferably from 10 μm to 60 μm. It should be noted that when using a support with a release layer, the overall thickness of the support with a release layer is preferably within the above range.

[0164] In the resin sheet, a protective film selected based on the support can be provided on the surface of the resin composition layer that is not joined to the support (i.e., the surface opposite to the support). The thickness of the protective film is not particularly limited and can be, for example, from 1 μm to 40 μm. By providing the protective film, it is possible to suppress the attachment of dirt, etc. or the generation of damage on the surface of the resin composition layer.

[0165] The resin sheet can be manufactured, for example, by coating a resin composition on a support using a die coater or the like to form a resin composition layer. If necessary, an organic solvent can be mixed in the resin composition and then coated on the support. When using an organic solvent, drying can be carried out as needed after coating.

[0166] Drying can be carried out, for example, by heating, hot air blowing, or other methods. The drying conditions are not particularly limited, and drying is carried out such that the content of the organic solvent in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Depending on the components contained in the resin composition, for example, by drying at 50°C to 150°C for 3 minutes to 10 minutes, a resin composition layer can be formed.

[0167] The resin sheet can be wound into a roll for storage. When the resin sheet has a protective film, it can usually be used by peeling off the protective film.

[0168] <Circuit Board and Its Manufacturing Method> The circuit board includes a cured product of the above resin composition. The specific structure of the circuit board is not limited as long as it includes the cured product of the resin composition. The circuit board according to the first example includes a substrate having holes and a cured product of the resin composition filled in the holes. In addition, the circuit board according to the second example includes a cured product layer including the cured product of the resin composition. Hereinafter, a method for manufacturing the circuit boards according to these first and second examples will be described. However, the circuit board and its manufacturing method are not limited to the first and second examples shown below.

[0169] <Circuit board according to the first example> The circuit board according to the first example includes a substrate formed with holes and a cured product of the resin composition filled in the holes. This circuit board can be manufactured, for example, by a manufacturing method including (1) a step of filling a resin composition into the holes of the substrate, and (2) a step of thermally curing the resin composition to obtain a cured product. In addition, the manufacturing method of the circuit board according to the first example may further include (3) a step of grinding the surface of the cured product or the resin composition, (4) a step of roughening the cured product, and (5) a step of forming a conductor layer on the cured product. Generally, the above steps (1) to (5) can be performed in the order of step (1), step (2), step (3), step (4), and step (5), or step (2) can be performed after step (3). In the manufacturing method of the circuit board according to the first example, it is preferable to use a paste-like resin composition to form the cured product. In the following description, an example of using a substrate formed with through holes (holes penetrating the substrate in the thickness direction) will be shown for illustration.

[0170] <Step (1)> Step (1) generally includes a step of preparing a substrate formed with through holes. The substrate can be prepared by purchasing it from the market. In addition, the substrate can be prepared by manufacturing it using a suitable material. Hereinafter, a manufacturing method of the substrate according to one example will be described.

[0171] Figure 1 is a cross-sectional view schematically showing the prepared core substrate 10 in the manufacturing method of the circuit board according to the first example of one embodiment of the present invention. The step of preparing the substrate is as Figure 1As in the example shown, the process may include preparing the core substrate 10. The core substrate 10 generally includes a support substrate 11. Examples of the support substrate 11 include insulating substrates such as glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. In addition, a metal layer may be provided on the support substrate 11. The metal layer may be provided on one side of the support substrate 11 or on both sides. Here, an example is shown in which the metal layer 12 and the metal layer 13 are provided on two surfaces of the support substrate 11. Examples of the metal layer 12 and the metal layer 13 include layers formed of a metal such as copper. The metal layer 12 and the metal layer 13 may be, for example, copper foils such as copper foils with carriers, or metal layers formed of the material of the conductor layer described later.

[0172] Figure 2 In the manufacturing method of the circuit board according to the first example of one embodiment of the present invention, a cross-sectional view of the core substrate 10 in which the through hole 14 is formed is schematically shown. The process of preparing the substrate may be as Figure 2 shown in the example, and may include a process of forming the through hole 14 in the core substrate 10. The through hole 14 can be formed by, for example, methods such as drilling, laser irradiation, and plasma irradiation. Generally, the through hole 14 can be formed by forming a through hole in the core substrate 10. If a specific example is given, the formation of the through hole 14 can be carried out using a commercially available drilling device. Examples of the commercially available drilling device include "ND-1S211" manufactured by Hitachi Vantara Corporation.

[0173] Figure 3 In the manufacturing method of the circuit board according to the first example of one embodiment of the present invention, a cross-sectional view of the core substrate 10 in which the plating layer 20 is formed in the through hole 14 is schematically shown. The process of preparing the substrate may include a process of forming the plating layer 20 as Figure 3 shown after performing a roughening treatment on the core substrate 10 as needed. As the aforementioned roughening treatment, any of dry and wet roughening treatments can be performed. Examples of the dry roughening treatment include plasma treatment. In addition, as an example of the wet roughening treatment, a method of sequentially performing a swelling treatment using a swelling liquid, a roughening treatment using an oxidizing agent, and a neutralization treatment using a neutralizing liquid can be given. The plating layer 20 can be formed by a plating method. The step of forming the plating layer 20 by the plating method can be the same as the formation of the conductor layer in the subsequent step (5). Here, an example in which the plating layer 20 is formed in the through hole 14, on the surface of the metal layer 12, and on the surface of the metal layer 13 is shown for explanation.

[0174] Figure 4In the manufacturing method of a circuit board according to the first example of an embodiment of the present invention, a cross-sectional view schematically showing a case where a resin composition 30a is filled in the through hole of the core substrate 10 is shown. Process (1) includes preparing the core substrate 10 having the through holes 14 as described above, and then, as Figure 4 shown, filling the resin composition 30a into the through holes 14 of the core substrate 10. The filling can be carried out, for example, by a printing method. Examples of the printing method include: a method of printing the resin composition 30a into the through hole 14 via a squeegee, a method of printing the resin composition 30a via a cartridge, a method of printing the resin composition 30a by mask printing, a roll coating method, an inkjet method, etc.

[0175] <Process (2)> Figure 5 A schematic cross-sectional view for explaining process (2) of the manufacturing method of a circuit board according to the first example of an embodiment of the present invention is shown. Process (2) includes, after filling the resin composition 30a into the through holes 14, Figure 5 as shown, curing the resin composition 30a to form a cured product 30.

[0176] The curing of the resin composition 30a is usually carried out by thermal curing. The thermal curing conditions of the resin composition 30a can be appropriately set within the range in which the curing of the resin composition 30a proceeds. The curing temperature is preferably 120°C or higher, more preferably 130°C or higher, further preferably 150°C or higher, preferably 245°C or lower, more preferably 220°C or lower, further preferably 200°C or lower. The curing time is preferably 5 minutes or longer, more preferably 10 minutes or longer, further preferably 15 minutes or longer, preferably 120 minutes or shorter, more preferably 110 minutes or shorter, further preferably 100 minutes or shorter.

[0177] The degree of curing of the cured product 30 obtained in process (2) is preferably 80% or higher, more preferably 85% or higher, further preferably 90% or higher. The degree of curing can be measured, for example, using a differential scanning calorimeter.

[0178] The manufacturing method of the circuit board according to the first example may include: a process (preheating process) of heating the resin composition 30a at a temperature lower than the curing temperature after filling the resin composition 30a into the through holes 14 and before curing the resin composition 30a. For example, before curing the resin composition 30a, the resin composition 30a can usually be preheated at a temperature of 50°C or higher and less than 120°C (preferably 60°C or higher and 110°C or lower, more preferably 70°C or higher and 100°C or lower) for usually 5 minutes or longer (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes).

[0179] <Process (3)> Figure 6 This is a schematic cross-sectional view of Process (3) of the method for manufacturing a circuit board according to the first example illustrating an embodiment of the present invention. When the resin composition 30a is filled into the through hole 14 in Process (1), the excess resin composition 30a may protrude or adhere outside the through hole 14. Therefore, the resin composition 30a can be provided not only inside the through hole 14 but also outside the through hole 14. Thus, Process (3) includes: as Figure 6 shown, grinding the excess cured product 30 that protrudes or adheres from the core substrate 10. By grinding, the excess cured product 30 can be removed, and thus the surface of the cured product 30 can be flattened. In addition, the surface (ground surface) 31 of the cured product 30 flattened by grinding generally forms a flush plane with the surrounding surface 21 (for example, the surface of the core substrate 10, the surface of the plating layer 20) of the ground surface 31.

[0180] As a method for grinding the cured product 30, a method capable of removing the excess cured product 30 that protrudes or adheres from the core substrate 10 can be adopted. As such a grinding method, for example, polishing, belt grinding, ceramic grinding, etc. can be cited. As a commercially available polishing device, for example, "NT-700IM" manufactured by Ishii Labeling Co., Ltd. can be cited.

[0181] Regarding the arithmetic mean roughness (Ra) of the ground surface 31 (cured surface) of the cured product 30, from the viewpoint of improving the adhesion to the conductor layer, it is preferably 300 nm or more, more preferably 350 nm or more, and further preferably 400 nm or more. The upper limit is preferably 1000 nm or less, more preferably 900 nm or less, and further preferably 800 nm or less. The surface roughness (Ra) can be measured using, for example, a non-contact surface roughness meter.

[0182] The method for manufacturing the circuit board according to the first example may include: after Process (3), a process of performing heat treatment on the cured product 30 in order to further improve the degree of curing of the cured product 30. The temperature in the aforementioned heat treatment may follow the above-mentioned curing temperature. Specifically, the heat treatment temperature is preferably 120°C or more, more preferably 130°C or more, and further preferably 150°C or more, and preferably 245°C or less, more preferably 220°C or less, and further preferably 200°C or less. The heat treatment time is preferably 5 minutes or more, more preferably 10 minutes or more, and further preferably 15 minutes or more, and preferably 90 minutes or less, more preferably 70 minutes or less, and further preferably 60 minutes or less.

[0183] In addition, when step (3) is carried out before step (2), a preheating treatment of heating at a temperature lower than the curing temperature of the resin composition can be carried out before step (3). The temperature in the above preheating treatment is preferably 100 °C or higher, more preferably 110 °C or higher, further preferably 120 °C or higher, preferably 245 °C or lower, more preferably 220 °C or lower, and further preferably 200 °C or lower. The heat treatment time is preferably 5 minutes or longer, more preferably 10 minutes or longer, further preferably 15 minutes or longer, preferably 90 minutes or shorter, more preferably 70 minutes or shorter, and further preferably 60 minutes or shorter.

[0184] <Step (4)> Step (4) includes subjecting the cured product 30 to a roughening treatment (decontamination treatment). By the roughening treatment, the surface of the cured product 30 is roughened. When the surface of the cured product 30 is polished, generally, a roughening treatment (decontamination treatment) is carried out on the polished surface 31. The steps and conditions of the roughening treatment are not particularly limited. For example, the steps and conditions used in the manufacturing method of a multilayer printed wiring board can be adopted. If specific examples are given, the cured product 30 can be subjected to a roughening treatment by sequentially carrying out a swelling treatment using a swelling liquid, a roughening treatment using an oxidant, and a neutralization treatment using a neutralization liquid.

[0185] Examples of the swelling liquid that can be used in the roughening step include, for example, an alkali solution, a surfactant solution, etc., and an alkali solution is preferred. Regarding the alkali solution as the swelling liquid, sodium hydroxide solution and potassium hydroxide solution are more preferred. Examples of commercially available swelling liquids include "Swelling Dip Securiganth P" and "Swelling Dip Securiganth SBU" manufactured by Atotech Japan Co., Ltd.

[0186] The swelling treatment using the swelling liquid can be carried out, for example, by immersing the cured product 30 in the swelling liquid at 30 °C to 90 °C for 1 minute to 20 minutes. From the viewpoint of controlling the swelling of the resin contained in the cured product 30 at an appropriate level, it is preferred to immerse the cured product 30 in the swelling liquid at 40 °C to 80 °C for 5 minutes to 15 minutes.

[0187] As the oxidizing agent that can be used for roughening treatment using an oxidizing agent, for example, an alkaline permanganic acid solution obtained by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide can be cited. The roughening treatment using an oxidizing agent such as an alkaline permanganic acid solution is preferably carried out by immersing the cured product 30 in a solution of the oxidizing agent heated to 60°C to 80°C for 10 minutes to 30 minutes. In addition, the concentration of the permanganate in the alkaline permanganic acid solution is preferably 5% by mass to 10% by mass. As commercially available oxidizing agents, for example, alkaline permanganic acid solutions such as "Concentrate Compact P" and "Dosing solution Securiganth P" manufactured by Atotech Japan Co., Ltd. can be cited.

[0188] As the neutralizing solution that can be used for neutralization treatment, an acidic aqueous solution is preferred. As commercially available products of the neutralizing solution, for example, "Reduction solution Securiganth P" manufactured by Atotech Japan Co., Ltd. can be cited. The neutralization treatment using the neutralizing solution can be carried out by immersing the treated surface that has undergone roughening treatment using an oxidizing agent solution in the neutralizing solution at 30°C to 80°C for 5 minutes to 30 minutes. From the perspective of operability and the like, a method of immersing the cured product 30 that has undergone roughening treatment using an oxidizing agent solution in the neutralizing solution at 40°C to 70°C for 5 minutes to 20 minutes is preferred.

[0189] As the arithmetic mean roughness (Ra) after the roughening treatment of the surface of the cured product 30, from the viewpoint of improving the adhesion to the conductor layer, it is preferably 300 nm or more, more preferably 350 nm or more, and further preferably 400 nm or more. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and further preferably 1000 nm or less. The surface roughness (Ra) can be measured using, for example, a non-contact surface roughness meter.

[0190] <Process (5)> Figure 7 It is a schematic cross-sectional view of process (5) for explaining the manufacturing method of the circuit board related to the first example of an embodiment of the present invention. Process (5) is as Figure 7 shown, and includes forming a conductor layer 40 on the ground surface 31 of the cured product 30. Here, an example is shown in which the conductor layer 40 is formed not only on the ground surface 31 of the cured product 30 but also on the surrounding surface 21 (for example, the surface of the core substrate 10, the surface of the plating layer 20). In addition, in Figure 7 , an example is shown in which the conductor layer 40 is formed on both sides of the core substrate 10, but the conductor layer 40 can be formed only on one side of the core substrate 10.

[0191] Figure 8This is a schematic cross-sectional view of step (5) of a method for manufacturing a circuit board according to a first example for explaining an embodiment of the present invention. As Figure 8 shown in Figure 8 , step (5) may include: after forming the conductor layer 40, removing a part of the conductor layer 40, the metal layer 12, the metal layer 13, and the plating layer 20 by processing such as etching to form a patterned conductor layer 41.

[0192] Regarding the method for forming the conductor layer 40, for example, plating methods, sputtering methods, evaporation plating methods, etc. can be cited. Among them, the plating method is preferably used. In a preferred embodiment, plating is performed on the surface of the cured product 30 (and the plating layer 20) by an appropriate method such as semi-additive method or full-additive method to form a patterned conductor layer 41 having a desired wiring pattern. As the material of the conductor layer 40, for example, single metals such as gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, indium, etc.; alloys of two or more metals selected from gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium can be cited. Among them, from the viewpoints of versatility, cost, ease of patterning, etc., it is preferable to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or nickel-chromium alloy, copper-nickel alloy, copper-titanium alloy, and more preferably to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or nickel-chromium alloy, and further more preferably to use copper.

[0193] Here, an example of a method for forming the patterned conductor layer 41 on the polished surface 31 of the cured product 30 will be described in detail. An electroless plating seed layer is formed on the polished surface 31 of the cured product 30 by electroless plating. Then, an electroplated layer is formed on the formed electroless plating seed layer by electroplating. Then, if necessary, the unnecessary electroless plating seed layer is removed by processing such as etching to form a patterned conductor layer 41 having a desired wiring pattern. After the patterned conductor layer 41 is formed, in order to improve the adhesion strength of the patterned conductor layer 41, annealing treatment can be performed if necessary. The annealing treatment can be performed, for example, by heating at 150 to 200 °C for 20 to 90 minutes.

[0194] From the viewpoint of thinning, the thickness of the patterned conductor layer 41 is preferably 70 μm or less, more preferably 60 μm or less, further preferably 50 μm or less, further more preferably 40 μm or less, particularly preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less, and the lower limit is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 5 μm or more.

[0195] Through the above method, a circuit board 1 including the cured product 30 of the resin composition 30a can be manufactured.

[0196] <Circuit Board According to the Second Example> The second example involves a circuit board including a cured product layer containing a cured product of a resin composition. The cured product layer preferably contains only the cured product of the resin composition. The cured product layer is preferably formed using a resin sheet. The circuit board can be manufactured, for example, by a manufacturing method including (i) a step of forming a cured product layer on an inner layer substrate, (ii) a step of performing an opening process on the cured product layer, (iii) a step of roughening the surface of the cured product layer, and (iv) a step of forming a conductor layer on the surface of the cured product layer.

[0197] <Step (i)> Step (i) includes forming a cured product layer on an inner layer substrate. Preferably, step (i) includes laminating a resin sheet on the inner layer substrate to bond the resin composition layer to the inner layer substrate and form a cured product layer. For example, the resin sheet is laminated on the inner layer substrate in such a manner that the resin composition layer is bonded to the inner layer substrate, and the resin composition layer is thermally cured to form a cured product layer.

[0198] Figure 9 is a schematic cross-sectional view for explaining step (i) in the manufacturing method of the circuit board according to the second example of an embodiment of the present invention. As Figure 9 shown, a resin sheet 310 including a support 330 and a resin composition layer 320a provided on the support 330 is prepared. Then, the resin sheet 310 is laminated with the inner layer substrate 200 in such a manner that the resin composition layer 320a is bonded to the inner layer substrate 200.

[0199] As the inner layer substrate 200, an insulating substrate can be used. Examples of the inner layer substrate 200 include insulating substrates such as glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The inner layer substrate 200 can be an inner layer circuit board in which wirings and the like are incorporated in its thickness.

[0200] The inner layer substrate 200 shown in this example has: a first conductor layer 420 provided on the first main surface 200a, and external terminals 240 provided on the second main surface 200b. The first conductor layer 420 can include a plurality of wirings. However, in Figure 9 the example shown, only the wirings constituting the coil-shaped conductive structure 400 (see Figure 12 ) of the inductor element are shown. The external terminals 240 can be terminals for electrically connecting to an external device (not shown) and the like. The external terminals 240 can be formed as a part of the conductor layer provided on the second main surface 200b.

[0201] Examples of the conductor material that can form the first conductor layer 420 and the external terminal 240 include the same materials as those of the conductor layer described in the first example.

[0202] The first conductor layer 420 and the external terminal 240 may have a single-layer structure, or may have a multi-layer structure formed by laminating two or more single-metal layers or alloy layers made of different metals or alloys. In addition, the thickness of the first conductor layer 420 and the external terminal 240 may be the same as that of the second conductor layer 440 described later.

[0203] There are no particular restrictions on the line width and line pitch (L / S) of the first conductor layer 420 and the external terminal 240. From the viewpoint of reducing surface irregularities and obtaining a cured product layer with excellent smoothness, it is usually 900 / 900 μm or less, preferably 700 / 700 μm or less, more preferably 500 / 500 μm or less, further preferably 300 / 300 μm or less, and even more preferably 200 / 200 μm or less. There is no particular limitation on the lower limit of the line width and line pitch (L / S). From the viewpoint of good filling of the resin composition layer into the wiring space, it is preferably 1 / 1 μm or more.

[0204] The inner layer substrate 200 may have a plurality of through holes 220 that penetrate the inner layer substrate 200 from the first main surface 200a to the second main surface 200b. Through-hole wirings 220a are provided in the through holes 220. The through-hole wirings 220a electrically connect the first conductor layer 420 and the external terminal 240.

[0205] The bonding of the resin composition layer 320a and the inner layer substrate 200 can be performed, for example, by thermocompression bonding the resin sheet 310 to the inner layer substrate 200 from the side of the support 330. Examples of the member for thermocompression bonding the resin sheet 310 to the inner layer substrate 200 (hereinafter also referred to as "thermocompression bonding member") include a heated metal plate (such as a stainless steel (SUS) end plate) or a metal roller (SUS roller). It should be noted that it is preferably not to directly contact the thermocompression bonding member with the resin sheet 310 for pressing, but to press through a sheet formed of an elastic material such as heat-resistant rubber, so that the resin sheet 310 can fully follow the surface irregularities of the inner layer substrate 200.

[0206] The temperature during thermocompression bonding is preferably in the range of 80°C to 160°C, more preferably in the range of 90°C to 140°C, and further preferably in the range of 100°C to 120°C. The pressure during thermocompression bonding is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably in the range of 0.29 MPa to 1.47 MPa. The time during thermocompression bonding is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. The bonding of the resin sheet and the inner layer substrate is preferably performed under reduced pressure conditions of 26.7 hPa or less.

[0207] The bonding of the resin composition layer 320a of the resin sheet 310 to the inner substrate 200 can be carried out using a commercially available vacuum laminator. As commercially available vacuum laminators, for example, a vacuum pressure type laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum coater manufactured by Nikko-Materials Co., Ltd., etc. can be cited.

[0208] After the resin sheet 310 is bonded to the inner substrate 200, under normal pressure (atmospheric pressure), for example, the heating and pressing member is pressed from the side of the support 330, whereby the smoothing treatment of the laminated resin sheet 310 can be carried out. The pressing conditions for the smoothing treatment can be set to the same conditions as the heating and pressing conditions for the above lamination. The smoothing treatment can be carried out using a commercially available laminator. It should be noted that the lamination and the smoothing treatment can be continuously carried out using the above-mentioned commercially available vacuum laminator.

[0209] Figure 10 It is a schematic cross-sectional view for explaining step (i) in the manufacturing method of the circuit board according to the second example of an embodiment of the present invention. After the resin sheet 310 is laminated on the inner substrate 200, the resin composition layer 320a is cured to form a cured product layer. In this example, as Figure 10 shown, the resin composition layer 320a bonded to the inner substrate 200 is thermally cured to form the first cured product layer 320.

[0210] The thermal curing conditions of the resin composition layer 320a can be appropriately set within the range where the curing of the resin composition proceeds. The curing temperature is preferably 120 °C or higher, more preferably 130 °C or higher, further preferably 150 °C or higher, preferably 245 °C or lower, more preferably 220 °C or lower, further preferably 200 °C or lower. The curing time is preferably 5 minutes or longer, more preferably 10 minutes or longer, further preferably 15 minutes or longer, preferably 120 minutes or shorter, more preferably 110 minutes or shorter, further preferably 100 minutes or shorter.

[0211] The support 330 can be removed between step (i) and step (ii) after the thermal curing, or can be peeled off after step (ii).

[0212] Regarding the arithmetic mean roughness (Ra) before the roughening treatment of the cured product layer, from the viewpoint of improving the adhesion with plating, it is preferably 300 nm or more, more preferably 350 nm or more, further preferably 400 nm or more. The upper limit is preferably 1000 nm or less, more preferably 900 nm or less, further preferably 800 nm or less. The surface roughness (Ra) can be measured using, for example, a non-contact type surface roughness meter.

[0213] In step (i), instead of the resin sheet, the resin composition may be coated on the inner layer substrate 200 using a die coater or the like and thermally cured to form a cured product layer.

[0214] <Process (ii)> Figure 11 This is a schematic cross-sectional view for explaining step (ii) in the method for manufacturing a circuit board according to a second example of an embodiment of the present invention. Step (ii) includes: as Figure 11 shown, via holes 360 are formed by performing through-hole machining on the first cured product layer 320. The via holes 360 form a path for electrically connecting the first conductor layer 420 to a second conductor layer 440 described later. For the formation of the via holes 360, for example, a drill, a laser, a plasma, etc. can be used. The size and shape of the holes can be appropriately determined according to the design of the printed wiring board.

[0215] <Process (iii)> In step (iii), the surface of the cured product layer having the via holes formed thereon is roughened. The roughening treatment in step (iii) can be performed using the same method as the method described in step (4) of the first example.

[0216] Regarding the arithmetic mean roughness (Ra) after the roughening treatment of the cured product layer, from the viewpoint of improving the adhesion to plating, it is preferably 300 nm or more, more preferably 350 nm or more, and further preferably 400 nm or more. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and further preferably 1000 nm or less. The surface roughness (Ra) can be measured using, for example, a non-contact surface roughness meter.

[0217] <Process (iv)> Figure 12 This is a schematic cross-sectional view for explaining step (iv) in the method for manufacturing a circuit board according to a second example of an embodiment of the present invention. As Figure 12 shown, in step (iv), a second conductor layer 440 is formed on the first cured product layer 320.

[0218] As the conductor material that can constitute the second conductor layer 440, the same materials as those of the conductor layer described in the first example can be cited.

[0219] 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, still more preferably 50 μm or less, even more preferably 40 μm or less, particularly more preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The lower limit is preferably 1 μm or more, more preferably 3 μm or more, still more preferably 5 μm or more.

[0220] The second conductor layer 440 can be formed by plating. The second conductor layer 440 is preferably formed by a wet plating method such as a semi-additive method or a full-additive method including, for example, an electroless plating process, a mask pattern formation process, an electrolytic plating process, and a flash etching process. By forming the second conductor layer 440 using a wet plating method, the second conductor layer 440 including a desired wiring pattern can be formed. It should be noted that, through this process, the via hole inner wiring 360a can be formed in the via hole 360 at the same time.

[0221] For the first conductor layer 420 and the second conductor layer 440, for example, as shown in an example described later Figures 13 - 15 it can be arranged in a spiral shape. In one example, one end on the center side in the spiral wiring portion of the second conductor layer 440 is electrically connected to one end on the center side in the spiral wiring portion of the first conductor layer 420 through the via hole inner wiring 360a. The other end on the outer peripheral side in the spiral wiring portion of the second conductor layer 440 is electrically connected to the land 420a of the first conductor layer 420 through the via hole inner wiring 360a. Therefore, the other end on the outer peripheral side in the spiral wiring portion of the second conductor layer 440 is electrically connected to the external terminal 240 through the via hole inner wiring 360a, the land 420a, and the through hole inner wiring 220a.

[0222] The coil-shaped conductive structure 400 is composed of a spiral wiring portion that is a part of the first conductor layer 420, a spiral wiring portion that is a part of the second conductor layer 440, and the via hole inner wiring 360a that electrically connects the spiral wiring portion of the first conductor layer 420 and the spiral wiring portion of the second conductor layer 440.

[0223] After the step (iv), a step of forming a cured product layer on the conductor layer can be further performed. As shown in an example described in Figure 14 a second cured product layer 340 is formed on the first cured product layer 320 on which the second conductor layer 440 and the via hole inner wiring 360a are formed. The second cured product layer can be formed by the same process as the process already described. Through the above method, the circuit board 100 including the first cured product layer 320 and the second cured product layer 340 formed of the cured product of the resin composition can be manufactured.

[0224] <Inductor Substrate> The inductor substrate includes the above-described circuit substrate. When such an inductor substrate includes a circuit substrate obtained by the manufacturing method of the circuit substrate according to the first example, at least a part of the periphery of the cured product of the resin composition may have an inductor pattern formed of a conductor. In this case, the inductor substrate may include, for example, an inductor element composed of an inductor pattern formed of at least a part of the metal layer 12, the metal layer 13, the plating layer 20, and the pattern conductor layer 41, and a core portion formed of the cured product 30 surrounded by the inductor pattern. Such an inductor substrate can be applied to, for example, the inductor substrate described in Japanese Patent Application Laid-Open No. 2016-197624.

[0225] In addition, when including a circuit substrate obtained by the manufacturing method of the circuit substrate according to the second example, the inductor substrate has a cured product layer and a conductive structure at least a part of which is buried in the cured product layer. And the inductor substrate may include an inductor element composed of the conductive structure and a part of the cured product layer that extends in the thickness direction of the cured product layer and is surrounded by the conductive structure.

[0226] Figure 13 FIG. is a schematic plan view of the circuit substrate 100 included in the inductor substrate as viewed from one side in its thickness direction. Figure 14 It is for showing Figure 13 a schematic view of the cut end face of the circuit substrate 100 cut at the position indicated by the II-II dotted line shown. Figure 15 FIG. is a schematic plan view for explaining the structure of the first conductor layer 420 of the circuit substrate 100 included in the inductor substrate.

[0227] As Figure 13 and Figure 14 shown as an example in, the circuit substrate 100 may be a substrate having a plurality of cured product layers (the first cured product layer 320, the second cured product layer 340) and a plurality of conductor layers (the first conductor layer 420, the second conductor layer 440). Therefore, in the example shown here, the circuit substrate 100 may be a stacked wiring board having stacked cured product layers and stacked conductor layers. In addition, the circuit substrate 100 includes an inner layer substrate 200.

[0228] As Figure 14As shown, the first cured layer 320 and the second cured layer 340 constitute the magnetic portion 300 of the cured layer that can be regarded as an integral body. Therefore, the coil-shaped conductive structure 400 is arranged in such a way that at least a part of it is buried in the magnetic portion 300. That is, in the circuit board 100 shown in this example, the inductor element is composed of the coil-shaped conductive structure 400 and a part of the magnetic portion 300, that is, the core portion, which extends in the thickness direction of the magnetic portion 300 and is surrounded by the coil-shaped conductive structure 400.

[0229] As Figure 15 shown as an example in, the first conductor layer 420 includes: a spiral wiring portion for forming the coil-shaped conductive structure 400, and a rectangular pad 420a electrically connected to the via inner wiring 220a. In the example shown here, the spiral wiring portion includes: a linear portion, a bent portion bent at a right angle, and a detour portion that detours at the pad 420a. In addition, the spiral wiring portion of the first conductor layer 420 has a shape with an overall contour that is substantially rectangular and is wound counterclockwise from the center side to the outside.

[0230] Similarly, a second conductor layer 440 is provided on the first cured layer 320. The second conductor layer 440 includes a spiral wiring portion for forming the coil-shaped conductive structure 400. Figure 13 Or Figure 14 in, the spiral wiring portion includes a linear portion and a bent portion bent at a right angle. Figure 13 Or Figure 14 in, the spiral wiring portion of the second conductor layer 440 has a shape with an overall contour that is substantially rectangular and is wound clockwise from the center side to the outside.

[0231] The above-mentioned inductor substrate can be used as a wiring board for mounting electronic components such as semiconductor chips, or as a (multi-layer) printed wiring board using the wiring board as an inner layer substrate. In addition, it can also be used as a chip inductor component obtained by making the wiring board into a single piece, or as a printed wiring board with the chip inductor component surface-mounted.

[0232] In addition, using the wiring board, semiconductor devices of various forms can be manufactured. The semiconductor device including the wiring board can be suitably used in electrical products (such as computers, mobile phones, digital cameras, and televisions, etc.) and transportation means (such as motorcycles, automobiles, trams, ships, and airplanes, etc.). Embodiment

[0233] Hereinafter, the present invention will be specifically described by way of examples. The present invention is not limited to these examples. It should be noted that hereinafter, unless otherwise specified, "%" and "parts" indicating quantity refer to "mass%" and "mass parts". In addition, the temperature condition in the case of not particularly specifying the temperature is room temperature (23°C). Further, the pressure condition in the case of not particularly specifying the pressure is normal pressure (1 atm).

[0234] <Example 1: Preparation of Varnish-Like Resin Composition 1> An Fe-Ni-Cr alloy magnetic powder (AKT-PB-2Cr manufactured by Mitsubishi Steel Manufacturing Co., Ltd., an alloy of Fe 52.2%, Ni 45.1%, Si 0.7%, Cr 1.9%, average particle diameter (D 50 ) 5 μm, true density 8.0 g / cm 3 ) 65.5 mass parts, an Mn-Zn ferrite powder (MZ03S_1 manufactured by Powdertech Co., Ltd., an Mn-Zn ferrite powder of Fe 48.2%, Mn 16.5%, Zn 6.3%, average particle diameter (D 50 ) 0.4 μm, true density 5.1 g / cm 3 ) 19.6 mass parts, an epoxy resin (ZX-1059 manufactured by Nippon Steel Chemical Materials Co., Ltd., a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, epoxy equivalent 169 g / eq., true density 1.2 g / cm 3 ) 1.63 mass parts, a phenolic resin (LA-7054 manufactured by DIC Corporation, an amino triazine-modified linear phenolic resin, a MEK solution with a non-volatile content of 60%, hydroxyl equivalent 125 g / eq., true density of the non-volatile content 1.2 g / cm 3 ) 1.85 mass parts, a phenoxy resin (YX7553BH30 manufactured by Mitsubishi Chemical Corporation, a solution of methyl ethyl ketone: cyclohexanone = 1:1 with a non-volatile content of 30%, a special skeleton phenoxy resin, true density of the non-volatile content 1.2 g / cm 3 ) 1.61 mass parts, a dispersant (PB-881 manufactured by Ajinomoto Fine-Techno Co., Inc., a polyester-based dispersant, true density 1.2 g / cm 3 ) 0.70 mass parts, and a curing accelerator (2E4MZ manufactured by Shikoku Kasei Kogyo Co., Ltd., an imidazole-based curing accelerator, true density 1.2 g / cm 3 ) 0.01 mass parts were uniformly dispersed to prepare varnish-like resin composition 1.

[0221] <Example 2: Preparation of Varnish-Like Resin Composition 2> In Example 1, 1) The amount of Fe-Ni-Cr alloy magnetic powder (“AKT-PB-2Cr” manufactured by Mitsubishi Steel Mfg. Co., Ltd.) was changed from 65.5 parts by mass to 56.4 parts by mass, 2) The amount of magnetic powder (“MZ03S_1” manufactured by Powdertech) was changed from 19.6 parts by mass to 25.0 parts by mass. Except for the above matters, a varnish-like resin composition 2 was prepared in the same manner as in Example 1.

[0236] <Example 3: Preparation of Varnish-Like Resin Composition 3> In Example 1, 1) The amount of Fe-Ni-Cr alloy magnetic powder (“AKT-PB-2Cr” manufactured by Mitsubishi Steel Mfg. Co., Ltd.) was changed from 65.5 parts by mass to 52.7 parts by mass, 2) The amount of Mn-Zn ferrite powder (“MZ03S_1” manufactured by Powdertech) was changed from 19.6 parts by mass to 27.9 parts by mass. Except for the above matters, a varnish-like resin composition 3 was prepared in the same manner as in Example 1.

[0237] <Example 4: Preparation of Varnish-Like Resin Composition 4> In Example 2, 25.0 parts by mass of Mn-Zn ferrite powder (“MZ03S_1” manufactured by Powdertech) was changed to 25.0 parts by mass of Mn ferrite powder (“M03S_1”, Mn ferrite powder with Fe 44.2% and Mn 25.1%, average particle size (D 50 ) 0.4 μm, true density 5.1 g / cm 3 ) Except for the above matters, a varnish-like resin composition 4 was prepared in the same manner as in Example 2.

[0238] <Example 5: Preparation of Varnish-Like Resin Composition 5> In Example 1, 19.6 parts by mass of Mn-Zn ferrite powder (“MZ03S_1” manufactured by Powdertech) was changed to 19.6 parts by mass of Mn ferrite powder (“M03S_3”, Fe-Mn ferrite powder with Fe 56.0% and Mn 13.9%, average particle size (D 50 ) 0.4 μm, true density 5.1 g / cm 3 ) Except for the above matters, a varnish-like resin composition 5 was prepared in the same manner as in Example 1.

[0239] <Example 6: Preparation of Varnish-Like Resin Composition 6> In Example 2, 25.0 parts by mass of the Mn-Zn ferrite powder ("MZ03S_1" manufactured by Powdertech) was changed to 25.0 parts by mass of the Mn ferrite powder ("M03S_3" manufactured by Powdertech, Mn ferrite powder with Fe 56.0% and Mn 13.9%, average particle size (D 50 ) 0.4 μm, true density 5.1 g / cm 3 ). Except for the above matters, a varnish-like resin composition 6 was prepared in the same manner as in Example 2.

[0240] <Example 7: Preparation of Varnish-like Resin Composition 7> In Example 1, 65.5 parts by mass of the Fe-Ni-Cr alloy magnetic powder ("AKT-PB-2Cr" manufactured by Mitsubishi Steel) was changed to 65.5 parts by mass of another Fe-Ni-Cr alloy magnetic powder ("AKT-PB-1Cr", alloy with Fe 53.3%, Ni 45.0%, Si 0.7%, Cr 1.0%, average particle size (D 50 ) 5 μm, true density 8.0 g / cm 3 ). Except for the above matters, a varnish-like resin composition 7 was prepared in the same manner as in Example 1.

[0241] <Example 8: Preparation of Varnish-like Resin Composition 8> In Example 1, 65.5 parts by mass of the Fe-Ni-Cr alloy magnetic powder ("AKT-PB-2Cr" manufactured by Mitsubishi Steel) was changed to 65.5 parts by mass of another Fe-Ni-Cr alloy magnetic powder ("AKT-PB-3Cr", alloy with Fe 51.0%, Ni 45.1%, Si 0.8%, Cr 3.1%, average particle size (D 50 ) 5 μm, true density 8.0 g / cm 3 ). Except for the above matters, a varnish-like resin composition 8 was prepared in the same manner as in Example 1.

[0242] <Example 9: Preparation of Varnish-like Resin Composition 9> In Example 1, 65.5 parts by mass of the Fe-Ni-Cr alloy magnetic powder ("AKT-PB-2Cr" manufactured by Mitsubishi Steel) was changed to 65.5 parts by mass of another Fe-Ni-Cr alloy magnetic powder ("AKT-PB-4Cr", alloy with Fe 49.4%, Ni 45.9%, Si 0.8%, Cr 3.9%, average particle size (D 50 ) 5 μm, true density 8.0 g / cm3 ) 65.5 parts by mass. Except for the above matters, a varnish-like resin composition 9 was prepared in the same manner as in Example 1.

[0243] <Comparative Example 1: Preparation of Varnish-Like Resin Composition 10> In Example 2, 25.0 parts by mass of the Mn-Zn ferrite powder ("MZ03S_1" manufactured by Powdertech Co., Ltd.) was changed to another Mn-Zn ferrite powder ("MZ03S_2" manufactured by Powdertech Co., Ltd., Mn-Zn ferrite powder with Fe 43.1%, Mn 22.2%, Zn 4.8%, average particle size (D 50 ) 0.4 μm, true density 5.1 g / cm 3 ) 25.0 parts by mass. Except for the above matters, a varnish-like resin composition 10 was prepared in the same manner as in Example 2.

[0244] <Comparative Example 2: Preparation of Varnish-Like Resin Composition 11> In Example 1, 19.6 parts by mass of the Mn-Zn ferrite powder ("MZ03S_1" manufactured by Powdertech Co., Ltd.) was changed to a Mn ferrite powder ("M03S_2" manufactured by Powdertech Co., Ltd., Mn ferrite powder with Fe 62.3%, Mn 8.1%, average particle size (D 50 ) 0.4 μm, true density 5.1 g / cm 3 ) 19.6 parts by mass. Except for the above matters, a varnish-like resin composition 11 was prepared in the same manner as in Example 1.

[0245] <Comparative Example 3: Preparation of Varnish-Like Resin Composition 12> In Example 1, 1) The amount of the Fe-Ni alloy magnetic powder ("AKT-PB-2Cr" manufactured by Mitsubishi Steel Mfg. Co., Ltd.) was changed from 65.5 parts by mass to 41.8 parts by mass, 2) The amount of the Mn-Zn ferrite powder ("MZ03S_1" manufactured by Powdertech Co., Ltd.) was changed from 19.6 parts by mass to 34.3 parts by mass. Except for the above matters, a varnish-like resin composition 12 was prepared in the same manner as in Example 1.

[0246] <Comparative Example 4: Preparation of Varnish-Like Resin Composition 13> In Example 2, 56.4 parts by mass of Fe-Ni-Cr alloy magnetic powder (“AKT-PB-2Cr” manufactured by Mitsubishi Steel Manufacturing Co., Ltd.) was changed to 56.4 parts by mass of Fe-Ni-Mo alloy magnetic powder (“AKT-78Ni-5Mo” manufactured by Mitsubishi Steel Manufacturing Co., Ltd., an alloy of Fe 16.4%, Ni 78.8%, Si 0.2%, Mo 4.5%, average particle size (D 50 ) 5 μm, true density 8.0 g / cm 3 ). Except for the above matters, the varnish-like resin composition 13 was prepared in the same manner as in Example 2.

[0247] <Manufacture of resin sheet> A PET film (“Lumirror R80” manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130 °C) that had been demolded with an alkyd resin-based mold release agent (“AL-5” manufactured by Lintec Corporation) was prepared as a support. The varnish-like resin compositions (resin varnishes) prepared in the examples and comparative examples were coated on the support using a die coater so that the thickness of the dried resin composition layer became 70 μm, and dried at 90 °C for 5 minutes to obtain a resin sheet.

[0248] <Manufacture of sheet-like cured body> The resin sheet was cut into a square with sides of 200 mm. Using a batch-type vacuum pressure laminator (two-stage stacked laminator “CVP700” manufactured by Nikko-materials Co., Ltd.), the cut resin sheet (200 mm square) was laminated on one side of a polyimide film (“UPILEX 25S” manufactured by Ube Industries, Ltd., 25 μm thick, 240 mm square) so that the central part of the smooth surface of the resin composition layer was in contact with the polyimide film. Lamination was carried out by reducing the pressure to 13 hPa or less for 30 seconds and then pressing at 100 °C and a pressure of 0.74 MPa for 30 seconds. Thereby, a multilayer film having a layer structure of support / resin composition layer / polyimide film was obtained.

[0249] After peeling off the support, the resin composition layer was thermally cured by heating at 190 °C for 90 minutes. Then, the polyimide film was peeled off to obtain a sheet-like cured body of the resin composition.

[0250] <Measurement of relative magnetic permeability and loss factor> The obtained sheet-like solid is cut to obtain an annular evaluation sample with an outer diameter of 19.2 mm and an inner diameter of 8.2 mm. Using the magnetic material test fixture "16454A" manufactured by Keysight Technologies and the impedance analyzer "E4991B" manufactured by Keysight Technologies, the relative magnetic permeability (μ') and magnetic loss (μ") of the evaluation sample are measured at a measurement frequency of 20 MHz and room temperature of 23 °C. The loss coefficient tanδ is calculated using the formula "tanδ = μ" / μ'".

[0251] The evaluation criteria for the relative magnetic permeability (μ') are as follows. "〇": The relative magnetic permeability is 23 or more. "×": The relative magnetic permeability is less than 23.

[0252] The evaluation criteria for the loss coefficient (tanδ) are as follows. "〇": The loss coefficient is 0.04 or less. "×": The loss coefficient exceeds 0.04.

[0253] [Table 1] [Table 1. Compositions and Results of Examples 1 to 6]

[0254] [Table 2] [Table 2. Compositions and Results of Examples 7 to 9 and Comparative Examples 1 to 4]

[0255] In the above Tables 1 and 2, "total amount of (A) component and (B) component (mass%)" represents the content relative to 100 mass% of the non-volatile components in the resin composition, and "total amount of (A) component and (B) component (volume%)" represents the content relative to 100 volume% of the non-volatile components in the resin composition. In addition, in the above Tables 1 and 2, the value of (Mn + Zn) / Fe in the (A) component and (B) component (mass ratio) represents the mass ratio of the total amount of Mn and Zn in the entire magnetic powder contained in the (A) component and (B) component to the amount of Fe. Symbol Explanation

[0256] 1 Circuit board 10 Core board 11 Support board 12 Metal layer 13 Metal layer 14 Through hole 20 Plated layer 21 Surface around the ground surface 30 Solidified product 30a Resin composition 31 Ground surface of the solidified product (ground surface) 40 conductor layer 41 patterned conductor layer 100 circuit board 200 inner layer substrate 200a first major surface 200b second major surface 220 via hole 220a in-via wiring 240 external terminal 310 resin sheet 320 first cured layer 320a resin composition layer 330 support 360 through hole 360a in-through hole wiring 400 coil-shaped conductive structure 420 first conductor layer 420a pad 440 second conductor layer.

Claims

1. A resin composition comprising (A) a magnetic powder of an Fe alloy system containing Ni, (B) a magnetic powder of a ferrite system containing Mn, and (C) a thermosetting resin, wherein Component (A) comprises an Fe-Ni-Cr alloy magnetic powder. Component (B) may or may not contain a magnetic powder of a ferrite system containing Zn. The mass ratio ((Mn + Zn) / Fe) of the total amount of Mn and Zn in the magnetic powders contained in components (A) and (B) to the amount of Fe is 0.055 or more and 0.16 or less.

2. The resin composition according to claim 1, wherein, (B) component has an average particle size (D 50 ) smaller than that of (A) component.

3. The resin composition according to claim 1, wherein, Component (C) comprises (C-1) an epoxy resin.

4. The resin composition according to claim 1, wherein, Component (C) comprises (C-2) a curing agent.

5. The resin composition according to claim 1, wherein, Further comprises (E) a thermoplastic resin.

6. The resin composition according to claim 1, wherein, Further comprises (F) a curing accelerator.

7. The resin composition according to claim 1, wherein, Further comprises (G) a dispersant.

8. The resin composition according to claim 1, wherein, Relative to 100% by mass of component (A), the content of Ni contained in component (A) is 33% by mass or more and 65% by mass or less.

9. The resin composition according to claim 1, wherein, Relative to 100% by mass of component (B), the content of Mn contained in component (B) is 5% by mass or more and 35% by mass or less.

10. The resin composition according to claim 1, wherein Relative to 100% by volume of the non-volatile components in the resin composition, the amount of component (A) is 30% by volume or more.

11. The resin composition according to claim 1, wherein, Relative to 100% by mass of the non-volatile components in the resin composition, the amount of component (A) is 40% by mass or more.

12. The resin composition according to claim 1, wherein, Relative to 100% by volume of the non-volatile components in the resin composition, the amount of component (B) is 10% by volume or more.

13. The resin composition according to claim 1, wherein, Relative to 100% by mass of the non-volatile components in the resin composition, the amount of component (B) is 10% by mass or more.

14. The resin composition according to claim 1, wherein, Relative to 100% by volume of the non-volatile components in the resin composition, the total amount of components (A) and (B) is 60% by volume or more.

15. The resin composition according to claim 1, wherein, Relative to 100% by mass of the non-volatile components in the resin composition, the total amount of components (A) and (B) is 70% by mass or more.

16. The resin composition according to claim 1, which is used for filling holes.

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

18. A magnetic paste, wherein, Comprises the resin composition according to any one of claims 1 to 16.

19. A resin sheet, wherein, Comprises a support and a resin composition layer provided on the support, The resin composition layer comprises the resin composition according to any one of claims 1 to 16.

20. A circuit board, wherein, Comprises: A substrate having holes, and A cured product of the resin composition according to any one of claims 1 to 16 filled in the holes.

21. A circuit board, wherein, Comprises a cured product layer comprising a cured product of the resin composition according to any one of claims 1 to 16.

22. An inductor substrate, wherein, Comprises the circuit board according to claim 21.

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