Resin composition

Abstract

To provide a resin composition capable of obtaining a cured material with improved specific magnetic permeability and reduced magnetic loss, and a magnetic sheet, circuit board, and inductor substrate obtained by using the resin composition.SOLUTION: A resin composition contains (A-1) magnetic powder with a compaction resistance of 1.0×105 Ω cm to 1.0×1013 Ω cm inclusive, (A-2) magnetic powder with a compaction resistance of 10 Ω cm to 1.0×104 Ω cm inclusive, and (B) a resin component.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a resin composition, a magnetic sheet, a circuit board, and an inductor board obtained using the resin composition.

Background Art

[0002] A circuit board such as a printed wiring board may be provided with a magnetic layer containing magnetic powder such as an inductor component. As the magnetic powder contained in the magnetic layer, in order to suppress the reduction of magnetic loss, for example, Patent Document 1 describes silicon oxide-coated soft magnetic powder obtained by surface-treating soft magnetic powder with silicon oxide.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For further improvement in performance of inductor components, a technique capable of forming a magnetic layer with low magnetic loss is required. When the present inventors studied the relative permeability and magnetic loss of the magnetic layer, they found that when trying to improve the relative permeability, the magnetic loss increases, and when trying to reduce the magnetic loss, the relative permeability decreases, and there is a trade-off relationship between the relative permeability and the magnetic loss.

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

Means for Solving the Problems

[0006] As a result of intensive studies by the present inventors, it has been found that by including a plurality of magnetic powders having different compacted powder resistance values in a resin composition, the trade-off relationship between the relative permeability and the magnetic loss can be eliminated, and in particular, the reduction of the magnetic loss becomes remarkable, leading to the completion of the present invention.

[0007] That is, the present invention includes the following. [1] A resin composition containing (A-1) a magnetic powder having a compacted powder resistance value of 1.0×10 5 Ω·cm or more and 1.0×10 13 Ω·cm or less, (A-2) a magnetic powder having a compacted powder resistance value of 10 Ω·cm or more and 1.0×10 4 Ω·cm or less, and (B) a resin component. [2] When the content (volume %) of the (A-1) component is a1 and the content (volume %) of the (A-2) component is a2 when the total of the (A-1) component and the (A-2) component is 100 volume %, the resin composition according to [1], wherein a1 / a2 is 0.10 or more and 5.00 or less. [3] The resin composition according to [1] or [2], wherein the total content (volume %) of the (A-1) component and the (A-2) component is 50 volume % or more when the non-volatile components in the resin composition are 100 volume %. [4] The resin composition according to any one of [1] to [3], wherein the (A-1) component and the (A-2) component are soft magnetic powders. [5] The resin composition according to any one of [1] to [4], wherein the (A-1) component and the (A-2) component are at least one selected from iron oxide powder and iron alloy-based metal powder. [6] The resin composition according to [5], wherein the iron oxide powder is a ferrite containing at least one selected from Ni, Cu, Mn, and Zn. [7] The resin composition according to [5], wherein the iron alloy-based metal powder is an iron alloy-based metal powder containing at least one selected from Fe, Si, Cr, Al, Ni, and Co. [8] The resin composition according to any one of [1] to [7], wherein the (A-1) component is an Mn-based ferrite. [9] The resin composition according to any one of [1] to [8], wherein the component (A-2) is at least one selected from the group consisting of Mz-Zn ferrite, Fe-Ni alloys, and Fe-Si alloys.

[10] The component (A-1) is Mn-based ferrite, The resin composition according to any one of [1] to [9], wherein the component (A-2) is at least one selected from the group consisting of Mz-Zn ferrite, Fe-Ni alloys, and Fe-Si alloys.

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

[10] , which is for forming an inductor element.

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

[11] , which is in a paste form.

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

[12] , which is for filling a through-hole.

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

[13] , wherein a cured product of the resin composition has a relative permeability of 5 or more at a frequency of 50 MHz.

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

[14] , wherein a cured product of the resin composition has a magnetic loss of 0.15 or less at a frequency of 50 MHz.

[16] A magnetic sheet comprising a support and a resin composition layer formed on the support from the resin composition according to any one of [1] to

[15] .

[17] A circuit board comprising: a substrate having a through-hole; and a cured product of the resin composition according to any one of [1] to

[15] filled in the through-hole.

[18] A circuit board comprising a magnetic layer which is a cured product of the resin composition according to any one of [1] to

[15] .

[19] An inductor substrate comprising the circuit substrate according to

[17] or

[18] . Effect of the Invention

[0008] According to the present invention, it is possible to provide a resin composition capable of giving a cured product having improved relative magnetic permeability and reduced magnetic loss, and a magnetic sheet, a circuit board, and an inductor board obtained using the resin composition. [Brief description of the drawings]

[0009]

Figure 1

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Figure 14

Figure 15

Figure 16

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that each drawing only schematically shows the shape, size, and arrangement of the components to the extent that the invention can be understood. The present invention is not limited by the following embodiments, and each component can be appropriately changed. Also, the configuration according to the embodiment of the present invention is not necessarily manufactured or used according to the arrangement shown in the drawings.

[0011] [Resin Composition] The resin composition of the present invention contains (A-1) magnetic powder having a compacted resistivity of 1.0×10 5 Ω·cm or more and 1.0×10 13 Ω·cm or less, (A-2) magnetic powder having a compacted resistivity of 10 Ω·cm or more and 1.0×10 4 Ω·cm or less, and (B) a resin component. In the present invention, by including magnetic powders having different compacted resistivities, namely, the (A-1) component and the (A-2) component, in the resin composition, it is possible to achieve both an improvement in the relative permeability and a reduction in magnetic loss of the cured product of this resin composition.

[0012] The resin composition may further contain (C) other additives as required. Hereinafter, each component contained in the resin composition of the present invention will be described in detail. Here, the components (A-1) and (A-2) may be collectively referred to as the “(A) component”.

[0013] <(A-1) The magnetic powder having a green compact resistivity of 1.0×10 5 Ω·cm or more and 1.0×10 13 Ω·cm or less, and (A-2) the magnetic powder having a green compact resistivity of 10 Ω·cm or more and 1.0×10 4 Ω·cm or less> The resin composition contains, as the component (A-1), a magnetic powder having a green compact resistivity of 1.0×10 5 Ω·cm or more and 1.0×10 13 Ω·cm or less, and, as the component (A-2), a magnetic powder having a green compact resistivity of 10 Ω·cm or more and 1.0×10 4 Ω·cm or less. By combining the components (A-1) and (A-2) and containing them in the resin composition, it is possible to achieve both an improvement in the relative permeability and a reduction in magnetic loss of the cured product. The components (A-1) and (A-2) may be used alone or in combination of two or more.

[0014] In this specification, the green compact resistivity refers to the volume resistivity obtained by forming a green compact by applying a load of 4 kN to 5 g of magnetic powder filled in a measuring container and measuring this green compact with a resistivity meter under the conditions of a temperature of 25°C and a humidity of 50%. The specific measuring method of the green compact resistivity can be measured according to the method described in the examples below.

[0015] As the green compact resistivity of the component (A-1), it is 1.0×10 5 Ω·cm or more, preferably 2.0×10 5 ·cm or more, more preferably 3.0×10 5 Ω·cm or more. As the upper limit, it is 1.0×10 13 Ω·cm or less, preferably 10 11 Ω·cm or less, more preferably 10 10It is below Ω·cm. By setting the compacted powder resistivity within such a range, it becomes possible to improve the relative permeability.

[0016] The compacted powder resistivity of the (A-2) component is 10 Ω·cm or more, preferably 1.0×10 2 Ω·cm or more, more preferably 2.0×10 2 Ω·cm or more. As the upper limit, it is 1.0×10 4 Ω·cm or less, preferably 2.0×10 3 Ω·cm or less, more preferably 1.0×10 3 Ω·cm or less. By setting the compacted powder resistivity within such a range, it becomes possible to reduce the loss factor.

[0017] When the content (volume %) of the (A-1) component when the total of the (A-1) component and the (A-2) component is 100% by volume is a1, and the content (volume %) of the (A-2) component when the total of the (A-1) component and the (A-2) component is 100% by volume is a2, a1 / a2 is preferably 0.10 or more, more preferably 0.50 or more, still more preferably 1.00 or more, preferably 5.00 or less, more preferably 4.00 or less, still more preferably 3.00 or less. By setting a1 / a2 within such a range, it becomes possible to achieve both an improvement in relative permeability and a reduction in magnetic loss.

[0018] According to the studies by the present inventors, it has been found that the larger the amount of the (A-1) component with a high compacted powder resistance value, the smaller the magnetic loss can be, while the relative permeability tends to decrease. Furthermore, it has been found that the larger the amount of the (A-2) component with a small compacted powder resistance value, the larger the relative permeability can be, while the magnetic loss tends to increase. Therefore, in the present invention, by combining the (A-1) component and the (A-2) component, both improvement of the relative permeability and reduction of the magnetic loss are achieved. Furthermore, according to the studies by the present inventors, it has been found that when the ratio of the contents of the (A-1) component and the (A-2) component is changed, the magnetic loss surprisingly undergoes a non-linear change. The range of the ratio a1 / a2 is set based on such findings to be a range in which an unexpected and remarkable effect due to the non-linear change can be obtained.

[0019] When the total content (volume %) of the (A-1) component and the (A-2) component is 100 volume % of the non-volatile components in the resin composition, it is preferably 30 volume % or more, more preferably 40 volume % or more, still more preferably 50 volume % or more, even more preferably 55 volume % or more, preferably 80 volume % or less, more preferably 75 volume % or less, and still more preferably 70 volume % or less. By setting the total content of the (A-1) component and the (A-2) component within such a range, both improvement of the relative permeability and reduction of the magnetic loss can be achieved.

[0020] When the content (mass %) of the (A-1) component is 100 mass % of the non-volatile components in the resin composition, from the viewpoint of improving the relative permeability, it is preferably 5 mass % or more, more preferably 10 mass % or more, still more preferably 20 mass % or more, 30 mass % or more, or 40 mass % or more. Also, it is preferably 98 mass % or less, more preferably 95 mass % or less, and still more preferably 90 mass % or less. In the present invention, unless otherwise specified, the content of each component in the resin composition is a value when the non-volatile components in the resin composition are 100 mass %.

[0021] The content (% by mass) of the component (A-2) is preferably 2% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, from the viewpoint of reducing the loss factor, when the non-volatile components in the resin composition are taken as 100% by mass. Further, it is preferably 95% by mass or less, more preferably 90% by mass or less, still more preferably 80% by mass or less, 70% by mass or less, or 60% by mass or less.

[0022] The total content (% by mass) of the component (A-1) and the component (A-2) is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, from the viewpoint of achieving both an improvement in relative permeability and a reduction in magnetic loss, when the non-volatile components in the resin composition are taken as 100% by mass. Further, it is preferably 98% by mass or less, more preferably 95% by mass or less, still more preferably 90% by mass or less.

[0023] As the component (A-1) and the component (A-2), either soft magnetic powder or hard magnetic powder may be used, but from the viewpoint of significantly obtaining the effects of the present invention, it is preferably soft magnetic powder.

[0024] Examples of the component (A-1) and the component (A-2) include oxide powders such as Mn-based ferrite, Fe-Mn-based ferrite, Fe-Mn-Zn-based ferrite, Mg-Zn-based ferrite, Mn-Zn-based ferrite, Mn-Mg-based ferrite, Cu-Zn-based ferrite, Mg-Mn-Sr-based ferrite, Ni-Zn-based ferrite, Ba-Zn-based ferrite, Ba-Mg-based ferrite, Ba-Ni-based ferrite, Ba-Co-based ferrite, Ba-Ni-Co-based ferrite, Y-based ferrite, iron oxide powder (III), and iron oxide powder such as magnetite; pure iron powder; iron alloy-based metal powders such as Fe-Ni-based alloy powder, Fe-Si-based alloy powder, Fe-Si-Al-based alloy powder, Fe-Cr-based alloy powder, Fe-Cr-Si-based alloy powder, Fe-Ni-Cr-based alloy powder, Fe-Cr-Al-based alloy powder, Fe-Ni-based alloy powder, Fe-Ni-Mo-based alloy powder, Fe-Ni-Mo-Cu-based alloy powder, Fe-Co-based alloy powder, or Fe-Ni-Co-based alloy powder; and amorphous alloys such as Co-based amorphous.

[0025] As the component (A-1) and the component (A-2), it is preferable that they are at least one selected from iron oxide powder and ferroalloy-based metal powder. As the iron oxide powder, it is preferable to contain ferrite containing at least one selected from Ni, Cu, Mn, and Zn. Further, as the ferroalloy-based metal powder, it is preferable to contain a ferroalloy-based metal powder containing at least one selected from Fe, Si, Cr, Al, Ni, and Co.

[0026] Among them, as the component (A-1), Mn-based ferrite is preferable, and as the component (A-2), it is preferable that it is at least one selected from Mn-Zn-based ferrite, Fe-Ni-based alloy, and Fe-Si-based alloy, and Mn-Zn-based ferrite is more preferable.

[0027] As the component (A-1), commercially available products can be used, and two or more kinds can be used in combination. Specific examples of commercially available magnetic powders that can be used include M series such as "M05S" manufactured by Powdertech Co., Ltd.; "Z10FG" manufactured by Nippon Heavy Chemical Industry Co., Ltd.; and the like.

[0028] As the component (A-2), commercially available products can be used, and two or more of them may be used in combination. Specific examples of commercially available magnetic powders that can be used include "Z05" manufactured by Powdertech Co., Ltd., "MZ05" manufactured by Powdertech Co., Ltd., "PST-S" manufactured by Sanyo Special Steel Co., Ltd., "AW2-08", "AW2-08PF20F", "AW2-08PF10F", "AW2-08PF3F", "AW08PF10F", "Fe-3.5Si-4.5CrPF20F", "Fe-50%NiPF10F", "Fe-50NiPF20F", "Fe-80Ni-4MoPF20F" manufactured by Epson Atmix Co., Ltd., and "LD-M", "LD-MH", "KNI-106", and "KNI-106GSM" manufactured by JFE Chemical Co., Ltd. "KNI-106GS", "KNI-109", "KNI-109GSM", "KNI-109GS"; "KNS-415", "BSF-547", "BSF-029", "BSN-125", "BSN-125", "BSN-714", "BSN-828", "S-1281", "S-1641", "S-1651", "S-1470", "S-1511", "S-2430" manufactured by Toda Kogyo Co., Ltd.; "JR09P2" manufactured by Japan Metals and Chemical Industries Co., Ltd.; "Nanotek" manufactured by CIK Nanotech Co., Ltd.; "JEMK-S" and "JEMK-H" manufactured by Kinsei Matec Co., Ltd.; and "Yttrium iron oxide" manufactured by ALDRICH.

[0029] The (A-1) component and the (A-2) component are preferably spherical. The value (aspect ratio) obtained by dividing the length of the long axis of the magnetic powder by the length of the short axis is preferably 2 or less, more preferably 1.5 or less, and even more preferably 1.2 or less. In general, it is easier to improve the relative magnetic permeability when the magnetic powder is flat rather than spherical. However, it is preferable to use spherical magnetic powder, in particular, from the viewpoint of obtaining a resin composition that can reduce magnetic loss and has a preferable viscosity.

[0030] From the viewpoint of improving the relative magnetic permeability, the average particle size of the (A-1) and (A-2) components is preferably 0.01 μm or more, more preferably 0.5 μm or more, and even more preferably 1 μm or more, and is preferably 10 μm or less, more preferably 9 μm or less, and even more preferably 8 μm or less.

[0031] (A-1) component and the average particle size of the (A-2) component can be measured by the laser diffraction / scattering method based on the Mie scattering theory. Specifically, the particle size distribution of the magnetic powder is created on a volume basis by a laser diffraction / scattering type particle size distribution measuring device, and it can be measured by taking the median diameter as the average particle size. As the measurement sample, a dispersion of the magnetic powder in water by ultrasonic waves can preferably be used. As the laser diffraction / scattering type particle size distribution measuring device, "LA-960" manufactured by Horiba, Ltd., "SALD-2200" manufactured by Shimadzu Corporation, etc. can be used.

[0032] (A-1) component and the specific surface area of the (A-2) component are preferably 0.05 m 2 / g or more, more preferably 0.1 m 2 / g or more, still more preferably 0.3 m 2 / g or more. Also, preferably 10 m 2 / g or less, more preferably 8 m 2 / g or less, still more preferably 5 m 2 / g or less. The specific surface area of the (A) component can be measured by the BET method.

[0033] (A-1) component and the true specific gravity of the (A-2) component are preferably 1.0 g / cm 3 or more, more preferably 3.0 g / cm 3 or more, still more preferably 4.0 g / cm 3 or more. Also, preferably 10.0 g / cm 3 or less, more preferably 9.0 g / cm 3 or less, still more preferably 8.0 g / cm 3 or less. The true specific gravity can be measured by the gas volume method. Specifically, the magnetic powder weighed with an electronic balance is measured for the volume of the magnetic powder using helium gas in accordance with JIS M8717 by a dry automatic densitometer ("Accupic II 1340 10CC" manufactured by Shimadzu Corporation), and it can be measured by taking the weighed value of the magnetic powder ÷ the volume value of the magnetic powder as the true specific gravity value.

[0034] (A-1) and (A-2) components may be treated with a surface treatment agent from the viewpoints of adjusting the viscosity of the resin composition and further enhancing the moisture resistance and dispersibility. Examples of the surface treatment agent include vinyl silane-based coupling agents, (meth)acrylic-based coupling agents, fluorine-containing silane coupling agents, amino silane-based coupling agents, epoxy silane-based coupling agents, mercapto silane-based coupling agents, silane-based coupling agents, alkoxysilanes, organosilazane compounds, titanate-based coupling agents, and the like. The surface treatment agent may be used alone or in any combination of two or more kinds.

[0035] Examples of commercially available products of the surface treatment agent include "KBM1003" (vinyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM503" (3-methacryloxypropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM403" (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM803" (3-mercaptopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-4803" (long-chain epoxy type silane coupling agent) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

[0036] From the viewpoint of improving the dispersibility of the (A) component, the degree of surface treatment with the surface treatment agent preferably falls within a predetermined range. Specifically, 100 parts by mass of the (A) component is preferably surface-treated with 0.01 to 5 parts by mass of the surface treatment agent, more preferably surface-treated with 0.05 to 3 parts by mass, and still more preferably surface-treated with 0.1 to 2 parts by mass.

[0037] <(B) resin component> The resin composition contains a (B) resin component as the (B) component. Examples of the (B) resin component include a (B-1) thermosetting resin, a (B-2) curing accelerator, a (B-3) dispersant, etc. As the (B) component, it is preferable to contain a (B-1) thermosetting resin, and it is more preferable to contain a (B-1) thermosetting resin and a (B-2) curing accelerator.

[0038] -(B-1) thermosetting resin- The (B) component may contain a (B-1) thermosetting resin. By containing the (B-1) component, it becomes possible to obtain a cured product excellent in mechanical properties and magnetic properties.

[0039] As the (B-1) thermosetting resin, for example, a thermosetting resin used when forming an insulating layer of a wiring board can be used. Examples of such a thermosetting resin include an epoxy resin, a phenol-based resin, a naphthol-based resin, a benzoxazine-based resin, an active ester-based resin, a cyanate ester-based resin, a carbodiimide-based resin, an amine-based resin, an acid anhydride-based resin, etc. Among them, it is preferable to contain an epoxy resin and a phenol-based resin, and it is more preferable to contain an epoxy resin.

[0040] The (B-1) thermosetting resin may be used alone or in combination of two or more. Here, components that react with an epoxy resin to cure the resin composition, such as a phenol-based resin, a naphthol-based resin, a benzoxazine-based resin, an active ester-based resin, a cyanate ester-based resin, a carbodiimide-based resin, an amine-based resin, and an acid anhydride-based resin, may be collectively referred to as a "curing agent".

[0041] Epoxy resins include, for example, glycidol-type epoxy resins; bisphenol A-type epoxy resins; bisphenol F-type epoxy resins; bisphenol S-type epoxy resins; bisphenol AF-type epoxy resins; dicyclopentadiene-type epoxy resins; tris-phenol-type epoxy resins; phenol novolac-type epoxy resins; tert-butyl-catechol-type epoxy resins; naphthol novolac-type epoxy resins, naphthalene-type epoxy resins, naphthol-type epoxy resins, anthracene-type epoxy resins and other epoxy resins having a condensed ring structure; glycidyl ether-type epoxy resins; glycidyl amine-type epoxy resins; glycidyl ester-type epoxy resins; cresol novolac-type epoxy resins; biphenyl-type epoxy resins; linear aliphatic epoxy resins; epoxy resins having a butadiene structure; alicyclic epoxy resins; heterocyclic epoxy resins; spiro ring-containing epoxy resins; cyclohexanedimethanol-type epoxy resins; trimethylol-type epoxy resins; tetraphenylethane-type epoxy resins and the like. The epoxy resin may be used alone or in combination of two or more. The epoxy resin is preferably at least one selected from bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and glycidyl ether-type epoxy resins.

[0042] The epoxy resin preferably includes an epoxy resin having two or more epoxy groups in one molecule. Further, the epoxy resin preferably has an aromatic structure, and when two or more epoxy resins are used, it is more preferable that at least one has an aromatic structure. The aromatic structure is a chemical structure generally defined as an aromatic group, and includes polycyclic aromatics and aromatic heterocycles. The proportion of the epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more based on 100% by mass of the non-volatile components of the epoxy resin.

[0043] The epoxy resin includes an epoxy resin that is liquid at a temperature of 25°C (hereinafter referred to as "liquid epoxy resin") There is also a solid epoxy resin (hereinafter sometimes referred to as "solid epoxy resin") at a temperature of 25°C. When an epoxy resin is contained as the component (B-1), the epoxy resin may contain only a liquid epoxy resin, only a solid epoxy resin, or a combination of a liquid epoxy resin and a solid epoxy resin. Among them, from the viewpoint of reducing the viscosity of the resin composition, it is preferable that the epoxy resin contains only a liquid epoxy resin.

[0044] Examples of the liquid epoxy resin include glycidol type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexanedimethanol type epoxy resins, and epoxy resins having a butadiene structure. Glycidyl ether type epoxy resins, bisphenol A type epoxy resins, and bisphenol F type epoxy resins are more preferred. Specific examples of the liquid epoxy resin include "HP4032", "HP4032D", "HP4032SS" (naphthalene type epoxy resin) manufactured by DIC Corporation; "828US", "jER828EL" (bisphenol A type epoxy resin), "jER807" (bisphenol F type epoxy resin), "jER152" (phenol novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "630" (glycidyl ether type aromatic epoxy resin), "630LSD" manufactured by Mitsubishi Chemical Corporation, "ED-523T" (glycidol type epoxy resin (Adeka glycidol)) manufactured by ADEKA Corporation, "EP-3980S" (glycidyl amine type epoxy resin), "EP-4088S" (dicyclopentadiene type epoxy resin); "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celloxide 2021P" (alicyclic epoxy resin having an ester skeleton), "PB-3600" (epoxy resin having a butadiene structure) manufactured by Daicel Corporation; "ZX1658", "ZX1658GS" (liquid 1,4-glycidylcyclohexane) manufactured by Nippon Steel Chemical Co., Ltd., etc. These may be used alone or in combination of two or more.

[0045] As the solid epoxy resin, naphthalene type tetrafunctional epoxy resin, cresol novolak type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol type epoxy resin, biphenyl type epoxy resin, naphthylene ether type epoxy resin, anthracene type epoxy resin, bisphenol A type epoxy resin, and tetraphenylethane type epoxy resin are preferred. Specific examples of the solid epoxy resin include "HP4032H" (naphthalene type epoxy resin), "HP-4700", "HP-4710" (naphthalene type tetrafunctional epoxy resin), "N-690" (cresol novolak type epoxy resin), "N-695" (cresol novolak type epoxy resin), "HP-7200", "HP-7200HH", "HP-7200H" (dicyclopentadiene type epoxy resin), "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether type epoxy resin) manufactured by DIC Corporation; "EPPN-502H" (trisphenol type epoxy resin), "NC7000L" (naphthol novolak type epoxy resin), "NC3000H", "NC3000", "NC3000L", "NC3100" (biphenyl type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V" (naphthalene type epoxy resin), "ESN485" (naphthol novolak type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YL6121" (biphenyl type epoxy resin), "YX4000HK" (bixylenol type epoxy resin), "YX8800" (anthracene type epoxy resin) manufactured by Mitsubishi Chemical Corporation; "PG-100", "CG-500" manufactured by Osaka Gas Chemical Co., Ltd., "YL7760" (bisphenol AF type epoxy resin), "YL7800" (fluorene type epoxy resin), "jER1010" (solid bisphenol A type epoxy resin), "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Corporation, and the like. These may be used alone or in combination of two or more.

[0046] When using a liquid epoxy resin and a solid epoxy resin in combination as the component (B-1), their quantitative ratio (liquid epoxy resin: solid epoxy resin) is preferably 1:0.1 to 1:4, more preferably 1:0.3 to 1:3.5, still more preferably 1:0.6 to 1:3, in terms of mass ratio. When the quantitative ratio of the liquid epoxy resin and the solid epoxy resin is within such a range, the desired effects of the present invention can be remarkably obtained.

[0047] The epoxy equivalent of the epoxy resin as the component (B-1) is preferably 50 g / eq. to 5000 g / eq., more preferably 50 g / eq. to 3000 g / eq., still more preferably 80 g / eq. to 2000 g / eq., and even more preferably 110 g / eq. to 1000 g / eq. By being within this range, the crosslinking density of the cured product can be sufficient to provide a magnetic layer with a small surface roughness. The epoxy equivalent can be measured in accordance with JIS K7236 and is the mass of the resin containing 1 equivalent of epoxy groups.

[0048] The weight average molecular weight of the epoxy resin as the component (B-1) is preferably 100 to 5000, more preferably 250 to 3000, still more preferably 400 to 1500. Here, the weight average molecular weight of the epoxy resin is the weight average molecular weight in terms of polystyrene measured by the gel permeation chromatography (GPC) method.

[0049] As the active ester resin, a resin having one or more active ester groups in one molecule can be used. Among them, as the active ester resin, a resin having two or more highly reactive ester groups such as phenolic esters, thiophenolic esters, N-hydroxyamine esters, esters of heterocyclic hydroxy compounds, etc. in one molecule is preferable. The active ester resin is preferably 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 preferable, and an active ester resin obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferable.

[0050] 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.

[0051] Examples of the phenol compound or naphthol compound include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene type diphenol compound, phenol novolak, etc. Here, the "dicyclopentadiene type diphenol compound" refers to a diphenol compound obtained by condensing two molecules of phenol with one molecule of dicyclopentadiene.

[0052] Preferable 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 phenol novolak, and an active ester resin containing a benzoylated product of phenol novolak. Among them, an active ester resin containing a naphthalene structure and an active ester resin containing a dicyclopentadiene-type diphenol structure are more preferable. The "dicyclopentadiene-type diphenol structure" represents a divalent structural unit composed of phenylene-dicyclopentylene-phenylene.

[0053] Commercially available products of the active ester resin include, as an active ester resin containing a dicyclopentadiene-type diphenol structure, "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T", "HPC-8000H-65TM", "EXB-8000L-65TM" (manufactured by DIC Corporation); as an active ester resin containing a naphthalene structure, "EXB9416-70BK", "EXB-8100L-65T", "EXB-8150L-65T", "EXB-8150-62T" (manufactured by DIC Corporation); as an active ester resin containing an acetylated product of phenol novolak, "DC808" (manufactured by Mitsubishi Chemical Corporation); as an active ester resin containing a benzoylated product of phenol novolak, "YLH1026" (manufactured by Mitsubishi Chemical Corporation); as an active ester resin that is an acetylated product of phenol novolak, "DC808" (manufactured by Mitsubishi Chemical Corporation); as an active ester resin that is a benzoylated product of phenol novolak, "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), "YLH1048" (manufactured by Mitsubishi Chemical Corporation); and the like.

[0054] As the phenol resin and the naphthol resin, those having a novolak structure are preferable from the viewpoints of heat resistance and water resistance. Also, from the viewpoint of adhesion to the conductor layer, a biphenyl-type resin, a naphthalene-type resin, a naphthylene ether-type resin, a phenol novolak-type resin, and a phenol-based curing agent containing a triazine skeleton are preferable.

[0055] Specific examples of the phenolic resin and the naphthol resin include, for example, "MEH-7700", "MEH-7810", "MEH-7851" manufactured by Meiwa Kasei Co., Ltd., "NHN", "CBN", "GPH" manufactured by Nippon Kayaku Co., Ltd., "SN170", "SN180", "SN190", "SN475", "SN485", "SN495", "SN-495V", "SN375", "SN395" manufactured by Nippon Steel Chemical & Material Co., Ltd., "EXB9500", "EXB-6000", "TD-2090", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "EXB-9500", etc. manufactured by DIC Corporation.

[0056] Specific examples of the benzoxazine resin include "JBZ-OD100" (benzoxazine ring equivalent: 218 g / eq.), "JBZ-OP100D" (benzoxazine ring equivalent: 218 g / eq.), "ODA-BOZ" (benzoxazine ring equivalent: 218 g / eq.) manufactured by JFE Chemical Corporation; "P-d" (benzoxazine ring equivalent: 217 g / eq.), "F-a" (benzoxazine ring equivalent: 217 g / eq.) manufactured by Shikoku Kasei Kogyo Co., Ltd.; "HFB2006M" (benzoxazine ring equivalent: 432 g / eq.) manufactured by Showa Highpolymer Co., Ltd., etc.

[0057] Examples of cyanate ester resins include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidenediphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanatephenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl)thioether, and bis(4-cyanatephenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; prepolymers in which part of these cyanate resins has been triazine-ized; and the like. Specific examples of cyanate ester resins include "PT30" and "PT60" (phenol novolac type polyfunctional cyanate ester resins), "ULL-950S" (polyfunctional cyanate ester resin), "BA230", "BA230S75" (prepolymer in which part or all of bisphenol A dicyanate has been triazine-ized to form a trimer), etc. manufactured by Lonza Japan Co., Ltd.

[0058] Specific examples of carbodiimide resins include Carbodilite (registered trademark) V-03 (carbodiimide group equivalent: 216 g / eq.), V-05 (carbodiimide group equivalent: 262 g / eq.), V-07 (carbodiimide group equivalent: 200 g / eq.), V-09 (carbodiimide group equivalent: 200 g / eq.) manufactured by Nisshinbo Chemical Inc.; and Stabaxol (registered trademark) P (carbodiimide group equivalent: 302 g / eq.) manufactured by Rhein Chemie.

[0059] Examples of the amine-based resin include resins having one or more amino groups in one molecule, such as aliphatic amines, polyether amines, alicyclic amines, aromatic amines, etc. Among them, from the viewpoint of achieving the desired effects of the present invention, aromatic amines are preferred. The amine-based resin is preferably a primary amine or a secondary amine, and more preferably a primary amine. Specific examples of the amine-based curing agent include 4,4'-methylenebis(2,6-dimethylaniline), diphenyldiaminosulfone, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, m-phenylenediamine, m-xylylenediamine, diethyltoluenediamine, 4,4'-diaminodiphenyl ether, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dihydroxybenzidine, 2,2-bis(3-amino-4-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. Commercially available products of the amine-based resin may be used, for example, "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.

[0060] Examples of the acid anhydride resin include resins having one or more acid anhydride groups in one molecule. Specific examples of the acid anhydride resin include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, hydrogenated methylnadic anhydride, trialkyltetrahydrophthalic anhydride, dodecenyl succinic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, naphthalene tetracarboxylic 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(anhydrotrimellitate), and polymer type acid anhydrides such as styrene-maleic acid resin copolymerized from styrene and maleic acid, etc.

[0061] (B-1) When the epoxy resin and the curing agent are contained as components, the quantitative ratio of the epoxy resin and all the curing agents is preferably in the range of [total number of epoxy groups of the epoxy resin]:[total number of reactive groups of the curing agent] at a ratio of 1:0.01 to 1:5, more preferably 1:0.5 to 1:3, and even more preferably 1:1 to 1:2. Here, the "number of epoxy groups of the epoxy resin" is the total value obtained by summing up the values obtained by dividing the mass of the non-volatile component of the epoxy resin present in the resin composition by the epoxy equivalent. Also, the "number of active groups of the curing agent" is the total value obtained by summing up the values obtained by dividing the mass of the non-volatile component of the curing agent present in the resin composition by the active group equivalent.

[0062] When containing (B-1) a thermosetting resin as the component (B), from the viewpoint of obtaining a cured product excellent in mechanical properties and magnetic properties, when the nonvolatile components in the resin composition are 100% by mass, the content of (B-1) the thermosetting resin is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more. The upper limit is not particularly limited as long as the effects of the present invention are achieved, but it is preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less.

[0063] -(B-2) Curing accelerator- The component (B) may contain (B-2) a curing accelerator. Examples of the curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, metal-based curing accelerators, etc. Phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, and metal-based curing accelerators are preferred, amine-based curing accelerators, imidazole-based curing accelerators, and metal-based curing accelerators are more preferred, and imidazole-based curing accelerators are still more preferred. (B-2) The curing accelerator may be used alone or in combination of two or more.

[0064] Examples of the phosphorus-based curing accelerator include triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, etc. Triphenylphosphine and tetrabutylphosphonium decanoate are preferred.

[0065] Examples of the amine-based curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, 1,8-diazabicyclo(5,4,0)undecene, etc., and 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)undecene are preferred.

[0066] Examples of imidazole-based curing accelerators include 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 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 and adducts of imidazole compounds and epoxy resins. Among them, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2-ethyl-4-methylimidazole, and 1-benzyl-2-phenylimidazole are preferred, and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine is more preferred.

[0067] As the imidazole-based curing accelerator, commercially available products may be used. For example, "2P4MZ" manufactured by Shikoku Kasei Co., Ltd., "P200-H50" manufactured by Mitsubishi Chemical Corporation, etc. may be mentioned.

[0068] As the guanidine-based curing accelerator, for example, dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-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. may be mentioned, and dicyandiamide, 1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred.

[0069] As the metal-based curing accelerator, for example, organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, tin, etc. may be mentioned. Specific examples of the organometallic complexes include organocobalt complexes such as cobalt(II) acetylacetonate, 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. Examples of the organometallic salts include zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, zinc stearate, etc.

[0070] When the component (B) contains a curing accelerator (B-2), from the viewpoint of obtaining a cured product with excellent mechanical properties, when the non-volatile components in the resin composition are 100% by mass, the content of the curing accelerator (B-2) is preferably 0.5% by mass or more, more preferably 1% by mass or more, still more preferably 1.5% by mass or more, and preferably 5% by mass or less, more preferably 4% by mass or less, still more preferably 3% by mass or less.

[0071] -(B-3) Dispersant- The component (B) may contain a dispersant (B-3). Examples of the dispersant (B-3) include phosphate ester-based dispersants such as polyoxyethylene alkyl ether phosphate; anionic dispersants such as sodium dodecylbenzene sulfonate, sodium laurate, and ammonium salts of polyoxyethylene alkyl ether sulfate; organosiloxane-based dispersants, polyoxyalkylene-based dispersants, acetylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkyl phenyl ether, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide and other non-ionic dispersants. Among these, non-ionic dispersants are preferred. The dispersant (B-3) may be used alone or in combination of two or more.

[0072] Commercially available products can be used as the phosphate ester-based dispersant. Examples of commercially available products include "RS-410", "RS-610", "RS-710", etc. of the "Phosphanol" series manufactured by Toho Chemical Industry Co., Ltd.

[0073] Examples of the organosiloxane-based dispersant include commercially available products such as "BYK347" and "BYK348" manufactured by BYK-Chemie GmbH.

[0074] Examples of polyoxyalkylene-based dispersants include commercially available products such as "Marlirem" series "AKM-0531", "AFB-1521", "SC-0505K", "SC-1015F", and "SC-0708A", and "HKM-50A" etc. manufactured by NOF Corporation. Polyoxyalkylene-based dispersants are a general term that encompasses polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl amines, polyoxyethylene alkyl amides, etc.

[0075] Examples of acetylene glycols include commercially available products such as "Surfynol" series "82", "104", "440", "465", and "485", and "Olefin Y" etc. manufactured by Air Products and Chemicals Inc.

[0076] When the component (B) contains the dispersant (B-3), from the viewpoint of significantly exerting the effects of the present invention, when the non-volatile components in the resin composition are 100% by mass, the content of the dispersant (B-3) is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, still more preferably 0.5% by mass or more, and the upper limit is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less.

[0077] Regarding the total content of the component (B), from the viewpoint of significantly exerting the effects of the present invention, when the non-volatile components in the resin composition are 100% by mass, it is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more. The upper limit is not particularly limited as long as the effects of the present invention are achieved, but it is preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less.

[0078] The (B) component may contain resin components other than the (B-1) component, (B-2) component, and (B-3) component. Examples of these resin components include thermoplastic resins such as phenoxy resin, flame retardants, thickeners, defoamers, leveling agents, adhesion promoters, and resin additives such as colorants.

[0079] <(C) Optional Additives> The resin composition may further contain optional additives as required. Examples of such other additives include organometallic compounds such as organic copper compounds, organic zinc compounds, and organic cobalt compounds.

[0080] The resin composition can be a paste-like composition that usually exhibits the property of having a low viscosity even without containing a solvent. Therefore, the content of the solvent contained in the resin composition is preferably less than 1.0% by mass, more preferably 0.8% by mass or less, still more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less, based on the total mass of the resin composition. The lower limit is not particularly limited, but it is 0.001% by mass or more, or it does not contain any. By using a usually liquid thermosetting resin or the like, the resin composition can have a low viscosity even without containing a solvent. By reducing the amount of the solvent in the resin composition, the generation of voids due to the volatilization of the solvent can be suppressed, and the handleability and workability can also be excellent.

[0081] <Method for Producing Resin Composition> The resin composition can be produced, for example, by a method of stirring the compounding components using a stirring device such as a three-roll mill or a rotary mixer.

[0082] <Physical Properties, etc. of Resin Composition> Since the resin composition contains the component (A-1) and the component (A-2) in combination, the cured product of the resin composition exhibits the property of having a high relative permeability. Therefore, the cured product of the resin composition provides a magnetic layer with a high relative permeability. The relative permeability of this cured product at a frequency of 50 MHz is preferably 5 or more, more preferably 6 or more, and even more preferably 7 or more. The upper limit is not particularly limited, but can be 20 or less, etc. The relative permeability can be measured according to the method described in the examples below.

[0083] Since the resin composition contains the component (A-1) and the component (A-2) in combination, the cured product of the resin composition exhibits the property of having a low magnetic loss. Therefore, the cured product of the resin composition provides a magnetic layer with a low magnetic loss. The magnetic loss of this cured product at a frequency of 50 MHz is preferably 0.15 or less, more preferably 0.1 or less, and even more preferably 0.08 or less. The lower limit is not particularly limited, but can be 0.001 or more, etc. The magnetic loss can be measured according to the method described in the examples below.

[0084] The resin composition usually exhibits the property of having a low viscosity. Therefore, the resin composition has the property of being in a paste state (paste-like resin composition) and can be suitably used as a resin composition for through-hole filling. Also, the resin composition can be suitably used as a resin composition for forming an inductor element for manufacturing an inductor element.

[0085] [Magnetic Sheet] The magnetic sheet includes a support and a resin composition layer formed of the resin composition of the present invention provided on the support.

[0086] From the viewpoint of thinning, the thickness of the resin composition layer is preferably 250 μm or less, more preferably 200 μm or less. The lower limit of the thickness of the resin composition layer is not particularly limited, but can usually be 5 μm or more, 10 μm or more, etc.

[0087] Examples of the support include a film made of a plastic material, a metal foil, and a release paper, with a film made of a plastic material and a metal foil being preferred.

[0088] When using a film made of a plastic material as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylic polymers such as polymethyl methacrylate (PMMA), cyclic polyolefin, 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.

[0089] When using a metal foil as the support, examples of the metal foil include a copper foil, an aluminum foil, etc., with a copper foil being preferred. As the copper foil, a foil made of single metal copper may be used, or a foil made of an alloy of copper and other metals (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0090] The support may be subjected to a mat treatment or a corona treatment on the surface that joins the resin composition layer.

[0091] Further, as the support, a support with a release layer having a release layer on the surface that joins with the resin composition layer may be used. Examples of the release agent used for the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. As the support with a release layer, commercially available products may be used. For example, "PET501010", "SK-1", "AL-5", "AL-7" manufactured by Lintec Corporation, which are PET films having a release layer mainly composed of an alkyd resin-based release agent; "Lumirror T60" manufactured by Toray Industries, Inc.; "Purex" manufactured by Teijin Limited; "Unipile" manufactured by Unitika Ltd., etc.

[0092] The thickness of the support is not particularly limited, but a range of 5 μm to 75 μm is preferable, and a range of 10 μm to 60 μm is more preferable. When using a support with a release layer, it is preferable that the total thickness of the support with a release layer is within the above range.

[0093] In the magnetic sheet, a protective film conforming to the support can be further laminated 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, but is, for example, 1 μm to 40 μm. By laminating the protective film, adhesion of dust or the like to the surface of the resin composition layer and scratches can be suppressed. The magnetic sheet can be stored by winding it into a roll. When the magnetic sheet has a protective film, it can be used by peeling off the protective film.

[0094] The magnetic sheet can be manufactured, for example, by applying a resin composition onto a support using a die coater or the like to form a resin composition layer. If necessary, a resin varnish dissolved in an organic solvent may be prepared and applied onto the support. When using an organic solvent, drying may be performed after application if necessary.

[0095] Drying may be carried out by methods such as heating and hot air blowing. The drying conditions are not particularly limited, but the drying is carried out so that the content of the organic solvent in the resin composition layer is 10% by mass or less, preferably 5% by mass or less. Although it varies depending on the components contained in the resin composition, the resin composition layer can be formed by drying at 50°C to 150°C for 3 minutes to 10 minutes.

[0096] The magnetic sheet can be stored by being wound into a roll. When the magnetic sheet has a protective film, it can be used by peeling off the protective film.

[0097] [Circuit Board and Its Manufacturing Method] The circuit board of the first embodiment includes a substrate having through holes and a cured product of the resin composition of the present invention filled in the through holes. Further, the circuit board of the second embodiment includes a magnetic layer formed by a cured product of the resin composition layer of the magnetic sheet. Hereinafter, the first embodiment and the second embodiment of the manufacturing method of the circuit board will be described. However, the manufacturing method of the circuit board according to the present invention is not limited to the first and second embodiments exemplified below.

[0098] <First Embodiment> The circuit board of the first embodiment is manufactured by a manufacturing method including, for example, the following steps (1) to (5). In the first embodiment, it is preferable to form a magnetic layer using a resin composition, and it is more preferable to form a magnetic layer using a paste-like resin composition. (1) A step of filling the through holes of a substrate having through holes with a resin composition, (2) A step of thermally curing the resin composition to obtain a cured product, (3) A step of polishing the surface of the cured product or the resin composition (4) A step of roughening the cured product, and (5) A step of forming a conductor layer on the surface of the cured product that has been roughened, are included. The manufacturing method of the circuit board of the present invention may be carried out in the order of steps (1) to (5), or step (2) may be carried out after step (3).

[0099] <Step (1)> In performing step (1), a step of preparing a resin composition may be included. The resin composition is as described above.

[0100] Also, in performing step (1), as shown in an example in FIG. 1, a step of preparing a core substrate 10 including a support substrate 11, and a first metal layer 12 and a second metal layer 13 made of a metal such as copper foil provided on both surfaces of the support substrate 11 may be included. Examples of the material 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. Examples of the material of the first and second metal layers include copper foil with a carrier, the material of the conductor layer described later, and the like.

[0101] Also, as shown in an example in FIG. 2, a step of forming a through hole 14 in the core substrate 10 may be included. The through hole 14 can be formed, for example, by drilling, laser irradiation, plasma irradiation, or the like. Specifically, the through hole 14 can be formed by forming a through hole in the core substrate 10 using a drill or the like.

[0102] The formation of the through hole 14 can be carried out using a commercially available drill device. Examples of commercially available drill devices include "ND-1S211" manufactured by Hitachi Via Mechanics, Ltd.

[0103] After forming the through hole 14 in the core substrate 10, as shown in an example in FIG. 3, a step of roughening the core substrate 10 and forming a plating layer 20 in the through hole 14, on the surface of the first metal layer 12, and on the surface of the second metal layer 13 may be included.

[0104] As the above-mentioned roughening treatment, either dry or wet roughening treatment may be performed. Examples of dry roughening treatment include plasma treatment and the like. Also, examples of wet roughening treatment include a swelling treatment with a swelling liquid, a roughening treatment with an oxidizing agent, and a method of performing a neutralization treatment with a neutralizing liquid in this order.

[0105] The plating layer 20 is formed by a plating method, and the procedure for forming the plating layer 20 by the plating method is the same as that for forming the conductor layer in step (5) described later.

[0106] After preparing the core substrate 10, as shown in an example in FIG. 4, the resin composition 30a is filled into the through holes 14. The filling can be performed, for example, by a printing method. Examples of the printing method include a method of printing the resin composition 30a into the through holes 14 through a squeegee, a method of printing the resin composition 30a through a cartridge, a method of mask printing to print the resin composition 30a, a roll coating method, an inkjet method, and the like.

[0107] <Step (2)> In step (2), after filling the resin composition 30a into the through holes 14, the resin composition 30a is thermally cured to form a cured product layer (magnetic layer) 30 in the through holes 14, as shown in an example in FIG. 5. The thermal curing conditions of the resin composition 30a vary depending on the composition and type of the resin composition 30a, but the curing temperature is preferably 120 ° C or higher, more preferably 130 ° C or higher, still more preferably 150 ° C or higher, and preferably 245 ° C or lower, more preferably 220 ° C or lower, still more preferably 200 ° C or lower. The curing time of the resin composition 30a is preferably 5 minutes or more, more preferably 10 minutes or more, still more preferably 15 minutes or more, and preferably 120 minutes or less, more preferably 100 minutes or less, still more preferably 90 minutes or less.

[0108] The degree of curing of the magnetic layer 30 in step (2) is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more. The degree of curing can be measured, for example, using a differential scanning calorimeter.

[0109] Before thermosetting the resin composition 30a, a preheating treatment may be performed on the resin composition 30a by heating it at a temperature lower than the curing temperature. For example, prior to thermosetting the resin composition 30a, the resin composition 30a may be preheated at a temperature of usually 50°C or higher and lower than 120°C (preferably 60°C or higher and 110°C or lower, more preferably 70°C or higher and 100°C or lower) for usually 5 minutes or longer (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes).

[0110] When performing step (3) after step (2), a heat treatment may be performed as necessary for the purpose of further increasing the degree of curing of the magnetic layer, etc. after step (2) and before step (3). The temperature in the heat treatment may be carried out according to the above-mentioned curing temperature, preferably 120°C or higher, more preferably 130°C or higher, still more preferably 150°C or higher, and preferably 245°C or lower, more preferably 220°C or lower, still more preferably 200°C or lower. The heat treatment time is preferably 5 minutes or longer, more preferably 10 minutes or longer, still more preferably 15 minutes or longer, and preferably 90 minutes or shorter, more preferably 70 minutes or shorter, still more preferably 60 minutes or shorter.

[0111] Also, when performing step (3) before step (2), a preheating treatment may be performed on the resin composition by heating it at a temperature lower than the curing temperature of the resin composition before step (3). The temperature in the preheating treatment is preferably 100°C or higher, more preferably 110°C or higher, still more preferably 120°C or higher, and preferably 245°C or lower, more preferably 220°C or lower, still more preferably 200°C or lower. The heat treatment time is preferably 5 minutes or longer, more preferably 10 minutes or longer, still more preferably 15 minutes or longer, and preferably 90 minutes or shorter, more preferably 70 minutes or shorter, still more preferably 60 minutes or shorter.

[0112] <Step (3)> In step (3), as shown in FIG. 6, the excess magnetic layer 30 protruding from or adhering to the core substrate 10 is removed by polishing and flattened. As the polishing method, a method capable of polishing the excess magnetic layer 30 protruding from or adhering to the core substrate 10 can be used. Examples of such polishing methods include buff polishing and belt polishing. Examples of commercially available buff polishing apparatuses include "NT-700IM" manufactured by Ishii Hyoki Co., Ltd.

[0113] The arithmetic mean roughness (Ra) of the polished surface of the magnetic layer (after heat curing of the magnetic layer) is preferably 300 nm or more, more preferably 350 nm or more, and still more preferably 400 nm or more from the viewpoint of improving the adhesion to plating. The upper limit is preferably 1000 nm or less, more preferably 900 nm or less, and still more preferably 800 nm or less. The surface roughness (Ra) can be measured, for example, using a non-contact surface roughness meter.

[0114] When step (3) is performed after step (2), heat treatment may be performed as necessary for the purpose of further increasing the degree of curing of the magnetic layer, etc. before step (3) after step (2). The temperature in the heat treatment may be carried out according to the above-described curing temperature, preferably 120°C or more, more preferably 130°C or more, and still more preferably 150°C or more, and preferably 245°C or less, more preferably 220°C or less, and still more preferably 200°C or less. The heat treatment time is preferably 5 minutes or more, more preferably 10 minutes or more, and still more preferably 15 minutes or more, and preferably 90 minutes or less, more preferably 70 minutes or less, and still more preferably 60 minutes or less.

[0115] Also, when performing step (3) before step (2), a preliminary heat treatment may be performed before step (3), in which heating is carried out at a temperature lower than the curing temperature of the resin composition. The temperature in the preliminary heat treatment is preferably 100°C or higher, more preferably 110°C or higher, still more preferably 120°C or higher, and preferably 245°C or lower, more preferably 220°C or lower, still more preferably 200°C or lower. The heat treatment time is preferably 5 minutes or longer, more preferably 10 minutes or longer, still more preferably 15 minutes or longer, and preferably 90 minutes or shorter, more preferably 70 minutes or shorter, still more preferably 60 minutes or shorter.

[0116] <Step (4)> In step (4), the surface polished in step (3) is roughened (desmear treatment). The procedures and conditions of the roughening step are not particularly limited, and known procedures and conditions commonly used in the manufacturing method of multilayer printed wiring boards can be adopted. As the roughening step, for example, the first magnetic layer 32 can be roughened by performing a swelling treatment with a swelling solution, a roughening treatment with an oxidizing agent, and a neutralization treatment with a neutralizing solution in this order.

[0117] The swelling solution that can be used in the roughening step is not particularly limited, and examples include an alkaline solution and a surfactant solution, and an alkaline solution is preferred. As the alkaline solution that is the swelling solution, a sodium hydroxide solution and a potassium hydroxide solution are more preferred. Commercially available swelling solutions include, for example, "Swelling Dip Security Gun P" and "Swelling Dip Security Gun SBU" manufactured by Atotech Japan Co., Ltd.

[0118] The swelling treatment with the swelling solution is not particularly limited, and for example, it can be performed by immersing the core substrate 20 provided with the first magnetic layer 32 in a swelling solution at 30°C to 90°C for 1 minute to 20 minutes. From the viewpoint of suppressing the swelling of the resin constituting the first magnetic layer 32 to an appropriate level, it is preferable to immerse the first magnetic layer 32 in a swelling solution at 40°C to 80°C for 5 minutes to 15 minutes.

[0119] The oxidizing agent that can be used for the roughening treatment with an oxidizing agent is not particularly limited. For example, an alkaline permanganate solution obtained by dissolving potassium permanganate or sodium permanganate in an aqueous solution of sodium hydroxide can be mentioned. The roughening treatment with an oxidizing agent such as an alkaline permanganate solution is preferably performed by immersing the first magnetic layer 32 in a solution of the oxidizing agent heated to 60°C to 80°C for 10 minutes to 30 minutes. Further, the concentration of the permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Examples of commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact P" and "Dosing Solution Security P" manufactured by Atotech Japan Co., Ltd.

[0120] As the neutralizing solution that can be used for the neutralization treatment, an acidic aqueous solution is preferable. Examples of commercially available products include "Reduction Solution Security P" manufactured by Atotech Japan Co., Ltd. The neutralization treatment with the neutralizing solution can be performed by immersing the treated surface that has been roughened with the oxidizing agent solution in the neutralizing solution at 30°C to 80°C for 5 minutes to 30 minutes. From the viewpoint of workability and the like, a method of immersing the first magnetic layer 32 that has been roughened with the oxidizing agent solution in the neutralizing solution at 40°C to 70°C for 5 minutes to 20 minutes is preferable.

[0121] The arithmetic mean roughness (Ra) after the roughening treatment of the magnetic layer is preferably 300 nm or more, more preferably 350 nm or more, and even more preferably 400 nm or more from the viewpoint of improving the adhesion to plating. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and even more preferably 1000 nm or less. The surface roughness (Ra) can be measured using, for example, a non-contact surface roughness meter.

[0122] <Step (5)> In step (5), as shown in an example in FIG. 7, a conductor layer 40 is formed on the polished surface of the magnetic layer 30 and on the core substrate. Further, after forming the conductor layer 40, as shown in an example in FIG. 8, a part of the conductor layer 40, the first metal layer 12, the second metal layer 13, and the plating layer 20 may be removed by a process such as etching to form a patterned conductor layer 41. In FIG. 7, the conductor layer 40 is formed on both surfaces of the core substrate 10, but the conductor layer 40 may be formed on only one surface of the core substrate 10.

[0123] Examples of the method for forming the conductor layer include plating, sputtering, vapor deposition, etc., and among them, the plating method is preferable. In a preferred embodiment, plating is performed on the surface of the cured product by an appropriate method such as a semi-additive method or a full-additive method to form a patterned conductor layer having a desired wiring pattern. Examples of the material of the conductor layer include single metals such as gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, indium, etc.; alloys of two or more metals selected from the group of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. 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 a nickel-chromium alloy, a copper-nickel alloy, a copper-titanium alloy, more preferably to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or a nickel-chromium alloy, and even more preferably to use copper.

[0124] Here, an example of an embodiment in which a patterned conductor layer is formed on a polished surface of a cured product will be described in detail. On the polished surface of the cured product, an electroless plating seed layer is formed by electroless plating. Next, an electrolytic plating layer is formed on the formed plating seed layer by electrolytic plating, and if necessary, an unnecessary plating seed layer is removed by a process such as etching to form a conductor layer having a desired wiring pattern. After forming the conductor layer, an annealing process may be performed if necessary for the purpose of improving the peel strength of the conductor layer. The annealing process can be performed, for example, by heating the circuit board at 150 to 200 °C for 20 to 90 minutes.

[0125] From the viewpoint of thinning, the thickness of the patterned conductor layer 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 preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The lower limit is preferably 1 μm or more, more preferably 3 μm or more, and still more preferably 5 μm or more.

[0126] <Second Embodiment> The circuit board of the second embodiment includes a magnetic layer formed of a cured product of a resin composition. In the second embodiment, it is preferable to form the magnetic layer using a magnetic sheet. Hereinafter, the second embodiment of the manufacturing method of the product substrate will be described. Parts where the description overlaps with the first embodiment will be omitted as appropriate.

[0127] The circuit board of the second embodiment is manufactured, for example, by a manufacturing method including the following steps (A) to (D). (A) A step of laminating a magnetic sheet on an inner layer substrate so that the resin composition layer is joined to the inner layer substrate to form a magnetic layer, (B) A step of drilling holes in the magnetic layer, (C) A step of roughening the surface of the magnetic layer, and (D) A step of forming a conductor layer on the polished surface of the magnetic layer, including.

[0128] Hereinafter, the above steps (A) to (D) in manufacturing the circuit board will be described in detail.

[0129] <Engineering (A)> Engineering (A) is a process of laminating a magnetic sheet on an inner layer substrate so that the resin composition layer is joined to the inner layer substrate to form a magnetic layer. As an embodiment of Engineering (A), a magnetic sheet is laminated on an inner layer substrate so that the resin composition layer is joined to the inner layer substrate, and the resin composition layer is thermally cured to form a magnetic layer.

[0130] In Engineering (A), as shown in an example in FIG. 9, a magnetic sheet 310 including a support 330 and a resin composition layer 320a provided on the support 330 is laminated on an inner layer substrate 200 so that the resin composition layer 320a is joined to the inner layer substrate 200.

[0131] The inner layer substrate 200 is an insulating substrate. Examples of the material of the inner layer substrate 200 include insulating base materials such as glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. The inner layer substrate 200 may be an inner layer circuit board in which wirings and the like are formed within its thickness.

[0132] As shown in an example in FIG. 9, the inner layer substrate 200 has a first conductor layer 420 provided on a first main surface 200a and an external terminal 240 provided on a second main surface 200b. The first conductor layer 420 may include a plurality of wirings. In the illustrated example, only the wirings constituting the coil-shaped conductive structure 400 of the inductor element are shown. The external terminal 240 is a terminal for electrically connecting to an external device or the like not shown. The external terminal 240 can be configured as a part of a conductor layer provided on the second main surface 200b.

[0133] The conductor materials that can form the first conductor layer 420 and the external terminal 240 are the same as the materials of the conductor layer described in the "<Engineering (5)>" column of the first embodiment.

[0134] The first conductor layer 420 and the external terminal 240 may have a single-layer structure or a multi-layer structure in which two or more single-metal layers or alloy layers made of different types of metals or alloys are laminated. Also, the thicknesses of the first conductor layer 420 and the external terminal 240 are the same as those of the second conductor layer 440 described later.

[0135] The line (L) / space (S) ratio of the first conductor layer 420 and the external terminal 240 is not particularly limited. However, from the viewpoint of reducing surface irregularities and obtaining a magnetic layer with excellent smoothness, it is usually 900 / 900 μm or less, preferably 700 / 700 μm or less, more preferably 500 / 500 μm or less, still more preferably 300 / 300 μm or less, and even more preferably 200 / 200 μm or less. The lower limit of the line / space ratio is not particularly limited, but from the viewpoint of favorably embedding the resin composition layer in the space, it is preferably 1 / 1 μm or more.

[0136] The inner layer substrate 200 may have a plurality of through holes 220 penetrating the inner layer substrate 200 from the first main surface 200a to the second main surface 200b. A through hole inner wiring 220a is provided in the through hole 220. The through hole inner wiring 220a electrically connects the first conductor layer 420 and the external terminal 240.

[0137] The bonding between the resin composition layer 320a and the inner layer substrate 200 can be performed, for example, by thermocompression bonding the magnetic sheet 310 to the inner layer substrate 200 from the support 330 side. Examples of the member for thermocompression bonding the magnetic sheet 310 to the inner layer substrate 200 (hereinafter also referred to as "thermocompression bonding member") include a heated metal plate (such as a stainless steel (SUS) mirror plate) or a metal roll (SUS roll). Note that it is preferable to press through a sheet made of an elastic material such as heat-resistant rubber so that the magnetic sheet 310 sufficiently follows the irregularities on the surface of the inner layer substrate 200, rather than directly contacting and pressing the thermocompression bonding member against the magnetic sheet 310.

[0138] The temperature during thermocompression bonding is preferably in the range of 80°C to 160°C, more preferably in the range of 90°C to 140°C, and even more preferably in the range of 100°C to 120°C. The pressure during thermocompression bonding is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably in the range of 0.29 MPa to 1.47 MPa. The time during thermocompression bonding is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. The bonding between the magnetic sheet and the inner layer substrate is preferably carried out under reduced pressure conditions of 26.7 hPa or less.

[0139] The bonding between the resin composition layer 320a of the magnetic sheet 310 and the inner layer substrate 200 can be carried out by a commercially available vacuum laminator. Examples of commercially available vacuum laminators include a vacuum pressure type laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nichco Materials Co., Ltd., and the like.

[0140] After bonding the magnetic sheet 310 and the inner layer substrate 200, under normal pressure (atmospheric pressure), for example, the heat-compressed member can be pressed from the support side to perform a smoothing treatment on the laminated magnetic sheet 310. The pressing conditions for the smoothing treatment can be the same as the heat-compression bonding conditions for the above lamination. The smoothing treatment can be carried out by a commercially available laminator. It should be noted that the lamination and the smoothing treatment may be carried out continuously using the above commercially available vacuum laminator.

[0141] After laminating the magnetic sheet on the inner layer substrate, the resin composition layer is thermally cured to form a magnetic layer. As shown in an example in FIG. 10, the resin composition layer 320a bonded to the inner layer substrate 200 is thermally cured to form the first magnetic layer 320.

[0142] The thermosetting conditions of the resin composition layer 320a vary depending on the composition and type of the resin composition. However, the curing temperature is preferably 120 °C or higher, more preferably 130 °C or higher, still more preferably 150 °C or higher, and preferably 245 °C or lower, more preferably 220 °C or lower, still more preferably 200 °C or lower. The curing time of the resin composition layer 320a is preferably 5 minutes or longer, more preferably 10 minutes or longer, still more preferably 15 minutes or longer, and preferably 120 minutes or shorter, more preferably 100 minutes or shorter, still more preferably 90 minutes or shorter.

[0143] The support 330 may be removed between the thermosetting in step (A) and step (B), or may be peeled off after step (B).

[0144] The arithmetic mean roughness (Ra) before the roughening treatment of the magnetic layer is preferably 300 nm or more, more preferably 350 nm or more, still more preferably 400 nm or more, from the viewpoint of improving the adhesion to plating. The upper limit is preferably 1000 nm or less, more preferably 900 nm or less, still more preferably 800 nm or less. The surface roughness (Ra) can be measured, for example, using a non-contact surface roughness meter.

[0145] In step (A), instead of the magnetic sheet, a resin composition may be applied onto the inner layer substrate using a die coater or the like and thermoset to form the magnetic layer.

[0146] <Step (B)> In step (B), as shown in an example in FIG. 11, the first magnetic layer 320 is drilled to form via holes 360. The via holes 360 serve as paths for electrically connecting the first conductor layer 420 and the second conductor layer 440, which will be described later. The formation of the via holes 360 may be carried out using, for example, a drill, a laser, a plasma, etc., depending on the composition of the resin composition used for the formation of the magnetic layer. The dimensions and shapes of the holes may be appropriately determined according to the design of the printed wiring board.

[0147] <Step (C)> In step (C), the surface of the magnetic layer in which via holes are formed is roughened. The roughening process in step (C) is as described in the "<Step (4)>" section of the first embodiment.

[0148] The arithmetic mean roughness (Ra) of the magnetic layer after the roughening process is preferably 300 nm or more, more preferably 350 nm or more, and even more preferably 400 nm or more from the viewpoint of improving the adhesion to plating. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and even more preferably 1000 nm or less. The surface roughness (Ra) can be measured using, for example, a non-contact surface roughness meter.

[0149] In step (C), instead of the roughening process, polishing may be performed to remove and planarize the excess magnetic layer protruding from or adhering to the core substrate 10. The polishing method is as described above.

[0150] <Step (D)> In step (D), as shown in an example in FIG. 12, a second conductor layer 440 is formed on the first magnetic layer 320.

[0151] The conductor material that can constitute the second conductor layer 440 is the same as the material of the conductor layer described in the "<Step (5)>" section of the first embodiment.

[0152] The thickness of the second conductor layer 440 is preferably 70 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less, even more preferably 40 μm or less, particularly preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less from the viewpoint of thinning. The lower limit is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more.

[0153] 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 forming process, an electrolytic plating process, and a flash etching process. By forming the second conductor layer 440 using the wet plating method, the second conductor layer 440 including a desired wiring pattern can be formed. Note that, by this process, an in-via wiring 360a is also formed in the via hole 360.

[0154] The first conductor layer 420 and the second conductor layer 440 may be provided in a spiral shape, as shown in an example in FIGS. 13 to 15 described later. In one example, one end on the center side of the spiral wiring portion of the second conductor layer 440 is electrically connected to one end on the center side of the spiral wiring portion of the first conductor layer 420 by the in-via wiring 360a. The other end on the outer peripheral side of the spiral wiring portion of the second conductor layer 440 is electrically connected to the land 420a of the first conductor layer 42 by the in-via wiring 360a. Therefore, the other end on the outer peripheral side of the spiral wiring portion of the second conductor layer 440 is electrically connected to the external terminal 240 through the in-via wiring 360a, the land 420a, and the through-via wiring 220a.

[0155] 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 in-via 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.

[0156] After the step (D), a step of forming a magnetic layer on the conductor layer may be further performed. Specifically, as shown in an example in FIG. 14, a second magnetic layer 340 is formed on the first magnetic layer 320 on which the second conductor layer 440 and the in-via wiring 360a are formed. The second magnetic layer may be formed by the same process as the process already described.

[0157] [Inductor Substrate] The inductor substrate includes the circuit substrate of the present invention. When such an inductor substrate includes a circuit substrate obtained by the manufacturing method of the circuit substrate of the first embodiment, it has an inductor pattern formed by a conductor on at least a part of the periphery of the cured product of the resin composition. As such an inductor substrate, for example, those described in JP-A-2016-197624 can be applied.

[0158] Further, when including a circuit substrate obtained by the manufacturing method of the circuit substrate of the second embodiment, the inductor substrate has a magnetic layer and a conductive structure at least partially embedded in this magnetic layer, and includes an inductor element constituted by a part of the magnetic layer that extends in the thickness direction of the conductive structure and is surrounded by the conductive structure. Here, FIG. 13 is a schematic plan view of an inductor substrate incorporating an inductor element as seen from one side in its thickness direction. FIG. 14 is a schematic view showing a cut end face of the inductor substrate cut at the position indicated by the II-II chain line shown in FIG. 13. FIG. 15 is a schematic plan view for explaining the configuration of the first conductor layer of the inductor substrate.

[0159] As shown as an example in FIGS. 13 and 14, the circuit substrate 100 has a plurality of magnetic layers (first magnetic layer 320, second magnetic layer 340) and a plurality of conductor layers (first conductor layer 420, second conductor layer 440), that is, it is a build-up wiring board having build-up magnetic layers and build-up conductor layers. Further, the inductor substrate 100 includes an inner layer substrate 200.

[0160] From FIG. 14, the first magnetic layer 320 and the second magnetic layer 340 constitute a magnetic portion 300 that can be regarded as an integral magnetic layer. Therefore, the coil-shaped conductive structure 400 is provided so as to be at least partially embedded in the magnetic portion 300. That is, in the inductor substrate 100 of the present embodiment, the inductor element is constituted by the coil-shaped conductive structure 400 and a core portion that is a part of the magnetic portion 300 that extends in the thickness direction of the magnetic portion 300 and is surrounded by the coil-shaped conductive structure 400.

[0161] As shown as an example in FIG. 15, the first conductor layer 420 includes a spiral wiring portion for forming the coil-shaped conductive structure 400 and a rectangular land 420a that is electrically connected to the wiring 220a within the through hole. In the illustrated example, the spiral wiring portion includes a bent portion that bends at a right angle to the linear portion and a detour portion that detours around the land 420a. In the illustrated example, the spiral wiring portion of the first conductor layer 420 has a shape in which the overall contour is substantially rectangular and is wound counterclockwise as it goes from the center side to the outside thereof.

[0162] Similarly, a second conductor layer 440 is provided on the first magnetic layer 320. The second conductor layer 440 includes a spiral wiring portion for forming the coil-shaped conductive structure 400. In FIG. 13 or FIG. 14, the spiral wiring portion includes a bent portion that bends at a right angle to the linear portion. In FIG. 13 or FIG. 14, the spiral wiring portion of the second conductor layer 44 has a shape in which the overall contour is substantially rectangular and is wound clockwise as it goes from the center side to the outside thereof.

[0163] Such an inductor substrate can be used as a wiring board for mounting electronic components such as semiconductor chips, and can also be used as a (multi-layer) printed wiring board using such a wiring board as an inner layer substrate. Further, such a wiring board can be used as a chip inductor component that is separated into individual pieces, and can also be used as a printed wiring board on which the chip inductor component is surface-mounted.

[0164] Also, various types of semiconductor devices can be manufactured using such a wiring board. A semiconductor device including such a wiring board can be suitably used in electrical products (for example, computers, mobile phones, digital cameras, televisions, etc.) and vehicles (for example, motorcycles, automobiles, trains, ships, airplanes, etc.).

Example

[0165] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "mass %", respectively, unless otherwise specified.

[0166] <Measurement of the Compaction Resistance Value of Magnetic Powder> The compaction resistance value of the magnetic powder was measured using a resistivity meter (powder resistivity measurement system manufactured by Mitsubishi Chemical Analytech Co., Ltd., MCP-PD51 type). Specifically, after filling 5 g of magnetic powder into a cylindrical measuring container with an inner diameter of 20 mm to form a magnetic powder layer, a load of 4 kN was applied to the upper surface of this magnetic powder layer for compaction to obtain a compacted body. The thickness and resistance value of the compacted body were measured in the state of being compacted (with a load of 4 kN applied) under the conditions of a temperature of 25°C and a humidity of 50%, and the volume resistivity of the compacted body was calculated from these and the inner diameter of the measuring container, and this was taken as the compaction resistance value.

[0167] <Example 1> Magnetic powder a (soft magnetic powder, Mn-based ferrite, manufactured by Powdertech Co., Ltd., "M05S", compaction resistance value at 4 kN; 1.5×10 6 Ω·cm, true specific gravity 5.0) was 35 parts by mass, and magnetic powder b (soft magnetic powder, Mn-Zn-based ferrite, manufactured by Powdertech Co., Ltd., "Z05", compaction resistance value at 4 kN; 4.5×10 3 Ω·cm, true specific gravity 5.0 g / cm 3 ) 16 parts by mass, to which 3 parts by mass of liquid epoxy resin a (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., "ZX-1059"), 3 parts by mass of liquid epoxy resin b (dicyclopentadiene type epoxy resin, manufactured by ADEKA Corporation, "EP-4088S"), 1 part by mass of liquid epoxy resin c (glycidyl ether type aromatic epoxy resin, manufactured by Mitsubishi Chemical Corporation, "630"), and 1 part by mass of curing accelerator a (imidazole-based curing accelerator, manufactured by Shikoku Kasei Co., Ltd., "2MZA-PW") were added, and they were uniformly dispersed with a high-speed rotary mixer to obtain resin composition 1.

[0168] <Example 2> In Example 1, The amount of magnetic powder a (soft magnetic powder, Mn-based ferrite, manufactured by Powdertech Co., Ltd., "M05S", specific resistance value under 4 kN; 1.5×10 6 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed from 35 parts by mass to 25.5 parts by mass, and the amount of magnetic powder b (soft magnetic powder, MnZn-based ferrite, manufactured by Powdertech Co., Ltd., "Z05", specific resistance value under 4 kN; 4.5×10 3 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed from 16 parts by mass to 25.5 parts by mass. Resin composition 2 was obtained in the same manner as in Example 1 except for the above matters.

[0169] <Example 3> In Example 1, the amount of magnetic powder a (soft magnetic powder, Mn-based ferrite, manufactured by Powdertech Co., Ltd., "M05S", specific resistance value under 4 kN; 1.5×10 6 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed from 35 parts by mass to 16 parts by mass, and the amount of magnetic powder b (soft magnetic powder, MnZn-based ferrite, manufactured by Powdertech Co., Ltd., "Z05", specific resistance value under 4 kN; 4.5×10 3 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed from 16 parts by mass to 35 parts by mass. Resin composition 3 was obtained in the same manner as in Example 1 except for the above matters.

[0170] <Example 4> In Example 1, the amount of magnetic powder a (soft magnetic powder, Mn-based ferrite, manufactured by Powdertech Co., Ltd., "M05S", specific resistance value under 4 kN; 1.5×10 6 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed from 35 parts by mass to 7 parts by mass, and the amount of magnetic powder b (soft magnetic powder, Mn-Zn-based ferrite, manufactured by Powdertech Co., Ltd., "Z05", specific resistance value under 4 kN; 4.5×10 3 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed from 16 parts by mass to 44 parts by mass. A resin composition 4 was obtained in the same manner as in Example 1 except for the above matters.

[0171] <Example 5> In Example 1, the amount of magnetic powder a (soft magnetic powder, Mn-based ferrite, manufactured by Powdertech Co., Ltd., "M05S", pressure resistance value at 4 kN; 1.5×10 6 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed from 35 parts by mass to 25.5 parts by mass, 16 parts by mass of magnetic powder b (soft magnetic powder, MnZn-based ferrite, manufactured by Powdertech Co., Ltd., "Z05", pressure resistance value at 4 kN; 4.5×10 3 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed to 35 parts by mass of magnetic powder c (soft magnetic powder, Fe-Si-based alloy, manufactured by Epson Atmix Corporation, "AW08PF10F", pressure resistance value at 4 kN; 2.3×10 3 Ω·cm, true specific gravity 7.0 g / cm 3 ). A resin composition 5 was obtained in the same manner as in Example 1 except for the above matters.

[0172] <Example 6> In Example 1, the amount of magnetic powder a (soft magnetic powder, Mn-based ferrite, manufactured by Powdertech Co., Ltd., "M05S", pressure resistance value at 4 kN; 1.5×10 6 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed from 35 parts by mass to 25.5 parts by mass, 16 parts by mass of magnetic powder b (soft magnetic powder, Mn-Zn-based ferrite, manufactured by Powdertech Co., Ltd., "Z05", pressure resistance value at 4 kN; 4.5×10 3 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed to 40 parts by mass of magnetic powder d (soft magnetic powder, Fe-Ni-based alloy, manufactured by Epson Atmix Corporation, "Fe-50%NiPF10F", pressure resistance value at 4 kN; 1.9×10 2 Ω·cm, true specific gravity 8.0 g / cm 3 ). A resin composition 6 was obtained in the same manner as in Example 1 except for the above matters.

[0173] <Comparative Example 1> In Example 1, the amount of magnetic powder a (soft magnetic powder, Mn-based ferrite, manufactured by Powdertech Co., Ltd., "M05S", press powder resistivity at 4 kN; 1.5×10 6 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed from 35 parts by mass to 51 parts by mass, and 16 parts by mass of magnetic powder b (soft magnetic powder, MnZn-based ferrite, manufactured by Powdertech Co., Ltd., "Z05", press powder resistivity at 4 kN; 4.5×10 3 Ω·cm, true specific gravity 5.0 g / cm 3 ) was not used. A resin composition 7 was obtained in the same manner as in Example 1 except for the above matters.

[0174] <Comparative Example 2> In Example 1, magnetic powder a (soft magnetic powder, Mn-based ferrite, manufactured by Powdertech Co., Ltd., "M05S", press powder resistivity at 4 kN; 1.5×10 6 Ω·cm, true specific gravity 5.0 g / cm 3 ) was not used, and the amount of magnetic powder b (soft magnetic powder, MnZn-based ferrite, manufactured by Powdertech Co., Ltd., "Z05", press powder resistivity at 4 kN; 4.5×10 3 Ω·cm, true specific gravity 5.0 g / cm 3 ) was changed from 16 parts by mass to 51 parts by mass. A resin composition 8 was obtained in the same manner as in Example 1 except for the above matters.

[0175] <Comparative Example 3> In Example 5, magnetic powder a (soft magnetic powder, Mn-based ferrite, manufactured by Powdertech Co., Ltd., "M05S", press powder resistivity at 4 kN; 1.5×10 6 Ω·cm, true specific gravity 5.0 g / cm 3 ) was not used, and magnetic powder c (soft magnetic powder, FeSi-based alloy, manufactured by Epson Atmix Corporation, "AW08PF10F", press powder resistivity at 4 kN; 2.3×10 3Ω·cm, true specific gravity 7.0 g / cm 3 The amount of ) was changed from 35 parts by mass to 70.5 parts by mass. A resin composition 9 was obtained in the same manner as in Example 5 except for the above matters.

[0176] <Comparative Example 4> In Example 6, Magnetic powder a (soft magnetic powder, Mn-based ferrite, manufactured by Powdertech Co., Ltd., "M05S", press powder resistivity at 4 kN; 1.5×10 6 Ω·cm, true specific gravity 5.0 g / cm 3 ) was not used, Magnetic powder d (soft magnetic powder, FeNi-based alloy, manufactured by Epson Atmix Corporation, "Fe-50%NiPF10F", press powder resistivity at 4 kN; 1.9×10 2 Ω·cm, true specific gravity 8.0 g / cm 3 The amount of ) was changed from 40 parts by mass to 80.5 parts by mass. A resin composition 10 was obtained in the same manner as in Example 6 except for the above matters.

[0177] <Measurement of relative permeability and magnetic loss> As a support, a polyethylene terephthalate (PET) film (manufactured by Lintec Corporation, "PET501010", thickness 50 μm) treated with a silicone-based release agent was prepared. Each of the resin compositions 1 to 10 was uniformly applied onto the release surface of the above PET film using a doctor blade so that the thickness of the resin composition layer after drying was 100 μm, and a magnetic sheet was obtained. The obtained magnetic sheet was heated at 180 °C for 90 minutes to thermally cure the resin composition layer, and the support was peeled off to obtain a sheet-like cured product. The obtained cured product was cut into toroidal test pieces with an outer diameter of 19 mm and an inner diameter of 9 mm to be used as evaluation samples. Using this evaluation sample and Keysight Technologies' "16454A E4991B", the relative permeability (μ') and the imaginary part (μ'') were measured at a measurement frequency of 50 MHz and at room temperature of 23 °C. The magnetic loss was calculated from μ'' / μ'.

[0178]

Table 1

[0179] It can be seen that Examples 1 to 6 are superior in relative permeability and have reduced magnetic loss compared to Comparative Examples 1 to 4.

[0180] Also, FIG. 16 shows a graph indicating the relationship between the content (volume %) of the (A-1) component and the relative permeability and magnetic loss in Examples 1 to 4 and Comparative Examples 1 to 2. From FIG. 16, it can be seen that Examples 1 to 4 containing the (A-1) component and the (A-2) component have an improved relative permeability compared to Comparative Example 1 not containing the (A-2) component. Also, it can be seen that Examples 1 to 4 have a significantly non-linearly reduced magnetic loss compared to Comparative Example 2 not containing the (A-1) component.

Explanation of Reference Signs

[0181] 10 Core substrate 11 Support substrate 12 First metal layer 13 Second metal layer 14 Through hole 20 Plating layer 30a Resin composition 30 Magnetic layer 40 Conductor layer 41 Pattern conductor layer 100 Circuit board 200 Inner layer substrate 200a First main surface 200b Second main surface 220 Through hole 220a Inner wiring in through hole 240 External terminal 300 Magnetic part 310 Magnetic sheet 320a Resin composition layer 320 First insulating layer 330 Support 340 Second insulating layer 360 Via hole 360a Wiring inside via hole 400 Coil-shaped conductive structure 420 First conductor layer 420a Land 440 Second conductor layer

Claims

1. (A-1) Magnetic powder with a compacted powder resistivity of 1.0×10 ５ Ω·cm or more and 1.0×1010 Ω·cm or less, (A-2) Magnetic powder with a compacted powder resistivity of 102 Ω·cm or more and 1.0×10 ４ Ω·cm or less, and (B) A resin component, and When the total content (volume %) of the (A-1) component and the (A-2) component is 100 volume %, the content (volume %) of the (A-1) component is a1, and the content (volume %) of the (A-2) component is a2, a resin composition in which a1 / a2 is 0.10 or more and 3.00 or less.

2. The resin composition according to claim 1, wherein the total content (volume %) of the (A-1) component and the (A-2) component is 50 volume % or more when the non-volatile components in the resin composition are 100 volume %.

3. The resin composition according to claim 1 or 2, wherein the (A-1) component and the (A-2) component are soft magnetic powders.

4. The resin composition according to any one of claims 1 to 3, wherein the (A-1) component and the (A-2) component are at least one selected from iron oxide powder and iron alloy-based metal powder.

5. The resin composition according to claim 4, wherein the iron oxide powder is a ferrite containing at least one selected from Ni, Cu, Mn, and Zn.

6. The resin composition according to claim 4, wherein the iron alloy-based metal powder is an iron alloy-based metal powder containing at least one selected from Fe, Si, Cr, Al, Ni, and Co.

7. The resin composition according to any one of claims 1 to 6, wherein the (A-1) component is an Mn-based ferrite.

8. The resin composition according to any one of claims 1 to 7, wherein the component (A-2) is at least one selected from Mz-Zn ferrites, Fe-Ni alloys, and Fe-Si alloys.

9. The component (A-1) is an Mn-based ferrite, The resin composition according to any one of claims 1 to 8, wherein the component (A-2) is at least one selected from Mz-Zn ferrites, Fe-Ni alloys, and Fe-Si alloys.

10. The resin composition according to any one of claims 1 to 9, which is for forming an inductor element.

11. The resin composition according to any one of claims 1 to 10, which is in paste form.

12. The resin composition according to any one of claims 1 to 11, which is for filling through-holes.

13. The resin composition according to any one of claims 1 to 12, wherein the relative permeability of the cured product of the resin composition at a frequency of 50 MHz is 5 or more.

14. The resin composition according to any one of claims 1 to 13, wherein the magnetic loss of the cured product of the resin composition at a frequency of 50 MHz is 0.15 or less.

15. A magnetic sheet including a support and a resin composition layer formed of the resin composition according to any one of claims 1 to 14 provided on the support.

16. A circuit board having a substrate with through-holes and a cured product of the resin composition according to any one of claims 1 to 14 filled in the through-holes.

17. A circuit board including a magnetic layer that is a cured product of the resin composition according to any one of claims 1 to 14.

18. An inductor substrate including the circuit board according to claim 16 or 17.

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