Resin composition

Abstract

An object of the present invention is to provide a resin composition and the like that can obtain a cured product having improved stain resistance and adhesion between a magnetic layer and a conductor layer, and suppressing the swelling of the conductor layer after reflow soldering treatment. The solution of the present invention is a resin composition containing (A) magnetic powder, (B-1) solid resin, (B-2) liquid resin, and (C) a curing accelerator having a melting point of 120°C or higher and 245°C or lower. When the content of the (B-1) component is denoted as b1 and the content of the (B-2) component is denoted as b2 when the non-volatile components in the resin composition are 100% by mass, b1 / b2 is 0.15 or higher and 0.45 or lower.

Description

Technical Field

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

[0002] In accordance with the recent requirements for miniaturization and thinning of electronic devices, there are also increasing requirements for miniaturization and thinning of printed wiring boards and inductor components (coils) mounted on printed wiring boards. When mounting an inductor component as a chip component, there is a limit to the thinning of the printed wiring board. Therefore, it is conceivable to form a magnetic layer on a printed substrate by using an adhesive film containing a magnetic material in a resin composition layer, thereby forming an inductor in the inner layer of the printed wiring board (for example, see Patent Document 1).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2015-187260. Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] The present inventors have recognized that when forming a conductor layer on a magnetic layer using a magnetic sheet containing a magnetic material in a resin composition layer or a paste-like resin composition, when performing a wet desmear treatment, due to the peeling and dissolution of the magnetic material caused by an oxidizing agent solution, the roughened shape of the surface of the magnetic layer deteriorates (i.e., the stain resistance (stain resistance) is poor). Therefore, there is a tendency for the adhesion between the magnetic layer and a conductor layer such as a plating layer to decrease. In addition, the present inventors have also recognized that if a reflow soldering treatment is performed, the conductor layer formed on the magnetic layer expands.

[0008] The present invention has been made in view of the above circumstances, and an object thereof is to provide a resin composition, a magnetic sheet obtained by using the resin composition, a circuit board, and an inductor board; the resin composition can obtain a cured product having improved stain resistance and adhesion between the magnetic layer and the conductor layer, and suppressing the expansion of the conductor layer after reflow soldering treatment.

[0009] Means for Solving the Problems

[0010] The present inventors have conducted in-depth research and found that by containing a solid resin and a liquid resin in the resin composition so as to achieve a specified content ratio, and further containing a curing accelerator having a melting point of 120°C or higher and 245°C or lower in the resin composition, the stain resistance and the adhesion between the magnetic layer and the conductor layer are improved, and the expansion of the conductor layer after reflow soldering treatment can be suppressed, thereby completing the present invention.

[0011] That is, the present invention includes the following:

[0012] [1] A resin composition comprising:

[0013] (A) Magnetic powder

[0014] (B-1) Solid resin

[0015] (B-2) Liquid resin, and

[0016] (C) A curing accelerator having a melting point of 120°C or higher and 245°C or lower

[0017] When the content of the component (B-1) is set as b1 and the content of the component (B-2) is set as b2, b1 / b2 is 0.15 or more and 0.45 or less. The content of the component (B-1) is the content when the non-volatile components in the resin composition are set as 100% by mass, and the content of the component (B-2) is the content when the non-volatile components in the resin composition are set as 100% by mass;

[0018] [2] The resin composition according to [1], wherein the component (B-1) contains a solid epoxy resin;

[0019] [3] The resin composition according to [1] or [2], wherein the component (B-2) contains a liquid epoxy resin;

[0020] [4] The resin composition according to any one of [1] to [3], wherein the component (C) has a triazine skeleton;

[0021] [5] The resin composition according to any one of [1] to [4], wherein the component (A) is a soft magnetic powder;

[0022] [6] The resin composition according to any one of [1] to [5], wherein the component (A) is iron oxide powder;

[0023] [7] The resin composition according to [6], wherein the iron oxide powder is a ferrite containing at least one element selected from Ni, Cu, Mn, and Zn;

[0024] [8] The resin composition according to any one of [1] to [7], wherein the component (A) is at least one selected from Fe-Mn-based ferrite and Fe-Mn-Zn-based ferrite;

[0025] [9] The resin composition according to any one of [1] to [8], wherein when the non-volatile components in the resin composition are set as 100% by mass, the content of the component (A) is 60% by mass or more;

[0026]

[10] The resin composition according to any one of [1] to [9], which is used for forming an inductor element;

[0027]

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

[10] , which is in paste form;

[0028]

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

[11] , which is used for filling through-holes;

[0029]

[13] A magnetic sheet, which comprises:

[0030] A support, and

[0031] A resin composition layer formed of the resin composition according to any one of [1] to

[12] provided on the support;

[0032]

[14] A circuit board, which includes:

[0033] A substrate having through-holes, and

[0034] A cured product of the resin composition according to any one of [1] to

[12] filled in the aforementioned through-holes;

[0035]

[15] A circuit board, which includes a magnetic layer that is a cured product of the resin composition according to any one of [1] to

[12] ;

[0036]

[16] An inductor substrate, which includes the circuit board described in

[14] or

[15] .

[0037] Effects of the Invention

[0038] According to the present invention, there can be provided: a resin composition capable of obtaining a cured product with improved stain resistance and adhesion between the magnetic layer and the conductor layer and suppressing the expansion of the conductor layer after reflow soldering treatment, and a magnetic sheet, a circuit board, and an inductor substrate obtained by using the resin composition. Description of the Drawings

[0039] Figure 1 It is a schematic cross-sectional view of a core substrate as an example of a method for manufacturing a circuit board according to the first embodiment;

[0040] Figure 2 It is a schematic cross-sectional view of a core substrate with through-holes formed as an example of a method for manufacturing a circuit board according to the first embodiment;

[0041] Figure 3 It is a schematic cross-sectional view showing the form of a core substrate with a plating layer formed in the through-holes as an example of a method for manufacturing a circuit board according to the first embodiment;

[0042] Figure 4 A schematic cross-sectional view showing the form of a core substrate filled with magnetic paste in a through hole, which is an example of a method for manufacturing a circuit board according to the first embodiment;

[0043] Figure 5 A schematic cross-sectional view showing the form of a core substrate after thermally curing the filled magnetic paste, which is an example of a method for manufacturing a circuit board according to the first embodiment;

[0044] Figure 6 A schematic cross-sectional view showing the form of a core substrate after grinding the cured product, which is an example of a method for manufacturing a circuit board according to the first embodiment;

[0045] Figure 7 A schematic cross-sectional view showing the form of a core substrate having a conductor layer formed on the ground surface, which is an example of a method for manufacturing a circuit board according to the first embodiment;

[0046] Figure 8 A schematic cross-sectional view showing the form of a core substrate having a patterned conductor layer formed thereon, which is an example of a method for manufacturing a circuit board according to the first embodiment;

[0047] Figure 9 A schematic cross-sectional view for explaining step (A) included in an example of a method for manufacturing a circuit board according to the second embodiment;

[0048] Figure 10 A schematic cross-sectional view for explaining step (A) included in an example of a method for manufacturing a circuit board according to the second embodiment;

[0049] Figure 11 A schematic cross-sectional view for explaining step (B) included in an example of a method for manufacturing a circuit board according to the second embodiment;

[0050] Figure 12 A schematic cross-sectional view for explaining step (D) included in an example of a method for manufacturing a circuit board according to the second embodiment;

[0051] Figure 13 A schematic top view of an inductor component as viewed from one side in its thickness direction, the inductor component including a circuit board obtained by the method for manufacturing a circuit board according to the second embodiment;

[0052] Figure 14 A schematic view showing the cut end face of an inductor component cut at the position indicated by the II-II dash-dot line, the inductor component including a circuit board obtained by the method for manufacturing a circuit board according to the second embodiment;

[0053] Figure 15 It is a schematic top view for explaining the structure of the first conductor layer in an inductor component as an example, and the inductor component includes a circuit board obtained by the manufacturing method of the circuit board of the second embodiment. Detailed Embodiment

[0054] Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that each drawing schematically shows the shape, size, and arrangement of the constituent elements only to the extent that the invention can be understood. The present invention is not limited by the following embodiments, and each constituent element can be appropriately changed. In addition, the configuration (structure) related to the embodiments of the present invention is not necessarily limited to being manufactured or used by the configuration illustrated in the drawings.

[0055] [Resin Composition]

[0056] The resin composition of the present invention contains (A) magnetic powder, (B-1) solid resin, (B-2) liquid resin, and (C) a curing accelerator having a melting point of 120°C or higher and 245°C or lower. When the content of the (B-1) component is denoted as b1 and the content of the (B-2) component is denoted as b2 when the non-volatile components in the resin composition are set to 100% by mass, b1 / b2 is 0.15 or higher and 0.45 or lower.

[0057] In the present invention, by containing a solid resin and a liquid resin in the resin composition so as to achieve a specified content ratio, and further containing a curing accelerator having a melting point of 120°C or higher and 245°C or lower in the resin composition, the stain resistance can be improved, and the expansion of the conductor layer after the reflow soldering process can be suppressed. Since the stain resistance of the magnetic layer is improved, the adhesion between the magnetic layer and the conductor layer can generally be improved. In addition, in the present invention, generally, the storage stability of the resin composition is excellent, and furthermore, for the cured product of the resin composition, the relative magnetic permeability can be improved at a frequency of 10 to 200 MHz.

[0058] The resin composition may further contain (D) other additives as needed. Hereinafter, each component contained in the resin composition of the present invention will be described in detail. Here, the (B-1) solid resin and the (B-2) liquid resin are sometimes collectively referred to as "(B) resin".

[0059] <(A) Magnetic Powder>

[0060] The resin composition contains (A) magnetic powder as the (A) component. By containing (A) magnetic powder in the resin composition, the relative magnetic permeability of its cured product can be improved. The (A) magnetic powder can be used alone or in combination of two or more.

[0061] As the (A) magnetic powder, it can be any of soft magnetic powders and hard magnetic powders. From the viewpoint of significantly obtaining the effects of the present invention, a soft magnetic powder is preferred.

[0062] Examples of the (A) magnetic powder include, for example, Fe-Mn ferrites, Fe-Mn-Zn ferrites, Mg-Zn ferrites, Mn-Zn ferrites, Mn-Mg ferrites, Cu-Zn ferrites, Mg-Mn-Sr ferrites, Ni-Zn ferrites, Ba-Zn ferrites, Ba-Mg ferrites, Ba-Ni ferrites, Ba-Co ferrites, Ba-Ni-Co ferrites, Y ferrites, iron oxide powders such as iron oxide powder (III) and magnetite; pure iron powders; iron alloy-based metal powders such as Fe-Si alloy powders, Fe-Si-Al alloy powders, Fe-Cr alloy powders, Fe-Cr-Si alloy powders, Fe-Ni-Cr alloy powders, Fe-Cr-Al alloy powders, Fe-Ni alloy powders, Fe-Ni-Mo alloy powders, Fe-Ni-Mo-Cu alloy powders, Fe-Co alloy powders, or Fe-Ni-Co alloy powders; amorphous alloys such as Co-based amorphous, etc.

[0063] Among them, as the (A) magnetic powder, at least one selected from iron oxide powders and iron alloy-based metal powders is preferred. As the iron oxide powder, it preferably contains: a ferrite containing at least one element selected from Ni, Cu, Mn, and Zn; more preferably at least one selected from Fe-Mn ferrites and Fe-Mn-Zn ferrites. In addition, as the iron alloy-based metal powder, it preferably contains: an iron alloy-based metal powder containing at least one element selected from Si, Cr, Al, Ni, and Co.

[0064] As the (A) magnetic powder, commercially available products can be used, or two or more types can be used in combination. Specific examples of commercially available magnetic powders that can be used include the M series such as "M05S" 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", "Fe-3.5Si-4.5CrPF20F", "Fe-50NiPF20F", "Fe-80Ni-4MoPF20F" manufactured by Epson Atmix Corporation; "LD-M", "LD-MH", "KNI-106", "KNI-106GSM", "KNI-106GS", "KNI-109", "KNI-109GSM", "KNI-109GS" manufactured by JFE Chemical Corporation; "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 Corporation; "JR09P2" manufactured by Nippon Heavy Chemical Industry Co., Ltd.; "Nanotek" manufactured by CIK Nano Technology Co., Ltd.; "JEMK-S", "JEMK-H" manufactured by Kinsei Matec Co., Ltd.; "Yttrium iron oxide" manufactured by ALDRICH Corporation, etc.

[0065] (A) The magnetic powder is preferably spherical. As the value obtained by dividing the length of the major axis of the magnetic powder by the length of the minor axis (aspect ratio), it is preferably 2 or less, more preferably 1.5 or less, and further preferably 1.2 or less. Generally, when the magnetic powder is in a non-spherical flat shape, it is easy to increase the relative magnetic permeability. However, generally, from the viewpoints of reducing magnetic loss and obtaining a resin composition having a preferable viscosity, it is particularly preferable to use spherical magnetic powder.

[0066] From the viewpoint of increasing the relative magnetic permeability, the average particle diameter of the (A) magnetic powder is preferably 0.01 μm or more, more preferably 0.5 μm or more, and further preferably 1 μm or more. In addition, it is preferably 10 μm or less, more preferably 9 μm or less, and further preferably 8 μm or less.

[0067] (A) The average particle diameter of the magnetic powder can be measured by the laser diffraction-scattering method based on the Mie scattering theory. Specifically, it can be measured in the following manner: Using a laser diffraction-scattering type particle size distribution measuring device, a particle size distribution of the magnetic powder is made on a volume basis, and the median particle diameter thereof is taken as the average particle diameter. As the sample for measurement, a product obtained by dispersing the magnetic powder in water using ultrasonic waves is preferably used. As the laser diffraction-scattering type particle size distribution measuring device, “LA-500” manufactured by Horiba, Ltd., “SALD-2200” manufactured by Shimadzu Corporation, etc. can be used.

[0068] From the viewpoint of improving the relative magnetic permeability, the specific surface area of the (A) magnetic powder is preferably 0.05 m 2 / g or more, more preferably 0.1 m 2 / g or more, and still more preferably 0.3 m 2 / g or more. Further, it is preferably 10 m 2 / g or less, more preferably 8 m 2 / g or less, and still more preferably 5 m 2 / g or less. The specific surface area of the (A) magnetic powder can be measured by the BET method.

[0069] From the viewpoint of adjusting the viscosity of the resin composition and further improving the moisture resistance and dispersibility, the (A) magnetic powder can be treated with a surface treatment agent. Examples of the surface treatment agent include vinylsilane-based coupling agents, (meth)acrylic acid-based coupling agents, fluorosilane coupling agents, aminosilane-based coupling agents, epoxy group-containing silane coupling agents, mercapto group-containing silane coupling agents, silane-based coupling agents, alkoxysilanes, organosilazane compounds, titanate-based coupling agents, etc. The surface treatment agent can be used alone as one kind, or two or more kinds can be arbitrarily combined and used.

[0070] Examples of commercially available surface treatment agents include "KBM1003" (vinyltriethoxysilane), "KBM503" (3-methacryloxypropyltriethoxysilane), "KBM403" (3-glycidoxypropyltrimethoxysilane), "KBM803" (3-mercaptopropyltrimethoxysilane), "KBE903" (3-aminopropyltriethoxysilane), "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), "SZ-31" (hexamethyldisilazane), "KBM103" (phenyltrimethoxysilane), "KBM-4803" (long-chain epoxy-type silane coupling agent), "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane), etc., all manufactured by Shin-Etsu Chemical Co., Ltd.

[0071] From the viewpoint of improving the dispersibility of (A) magnetic powder, the degree of surface treatment with the surface treatment agent is preferably limited to a specified range. Specifically, with respect to 100 parts by mass of (A) magnetic powder, it is preferably surface-treated with 0.01 part by mass to 5 parts by mass of the surface treatment agent, more preferably surface-treated with 0.05 part by mass to 3 parts by mass, and further preferably surface-treated with 0.1 part by mass to 2 parts by mass.

[0072] With respect to the content (volume %) of (A) magnetic powder, from the viewpoints of improving the relative magnetic permeability and reducing the loss factor, when the non-volatile components in the resin composition are set to 100 volume %, it is preferably 40 volume % or more, more preferably 50 volume % or more, and further preferably 60 volume % or more. In addition, it is preferably 85 volume % or less, more preferably 80 volume % or less, and further preferably 70 volume % or less.

[0073] Regarding the content (mass %) of the (A) magnetic powder, from the viewpoints of improving the relative magnetic permeability and reducing the loss coefficient, when the non-volatile components in the resin composition are set to 100 mass%, it is preferably 60 mass% or more, more preferably 70 mass% or more, and further preferably 75 mass% or more. In addition, it is preferably 98 mass% or less, more preferably 95 mass% or less, and further preferably 90 mass% or less. It should be noted that in the present invention, unless otherwise clearly stated, the content of each component in the resin composition is the value when the non-volatile components in the resin composition are set to 100 mass%. Generally, the higher the content of the (A) magnetic powder in the resin composition, the more significant the decrease in stain resistance, the decrease in the adhesion between the magnetic layer and the conductor layer, and the occurrence of swelling of the conductor layer after reflow soldering treatment, which are the problems of the present invention. However, in the resin composition of the present invention, even if the content of the (A) magnetic powder is as high as described above, a cured product with improved stain resistance and adhesion between the magnetic layer and the conductor layer, and suppression of swelling of the conductor layer after reflow soldering treatment can be obtained.

[0074] <(B-1) Solid Resin and (B-2) Liquid Resin>

[0075] The resin composition contains a (B-1) solid resin as the (B-1) component and a (B-2) liquid resin as the (B-2) component. By using the (B-1) solid resin and the (B-2) liquid resin in a specified content ratio, the stain resistance and adhesion can be improved, and the swelling of the conductor layer after reflow soldering treatment can be suppressed. Moreover, the storage stability becomes excellent.

[0076] The so-called (B-1) solid resin refers to a resin that is solid at a temperature of 20°C; the so-called (B-2) liquid resin refers to a resin that is liquid at a temperature of 20°C. The (B-1) component and the (B-2) component can each be used alone in one kind, or two or more kinds can be used in combination.

[0077] When the content of the (B-1) component when the non-volatile components in the resin composition are set to 100 mass% is denoted as b1, and the content of the (B-2) component when the non-volatile components in the resin composition are set to 100 mass% is denoted as b2, b1 / b2 is 0.15 or more, preferably 0.17 or more, more preferably 0.2 or more, and further preferably 0.23 or more. The upper limit is 0.45 or less, preferably 0.4 or less, more preferably 0.35 or less, and further preferably 0.3 or less. By making b1 / b2 within the above range, the swelling of the conductor layer after reflow soldering treatment can be suppressed, and the storage stability becomes excellent.

[0078] As the resin (B), a thermosetting resin is generally used. Examples of the thermosetting resin include, for example, epoxy resins, phenol-based resins (phenolic resins), naphthalene-based resins, benzoxazine-based resins, active ester-based resins, cyanate ester-based resins, carbodiimide-based resins, amine-based resins, acid anhydride-based resins, etc. Resins that are solid at a temperature of 20°C, including the resins exemplified herein, are classified as (B-1) solid resins, and resins that are liquid at a temperature of 20°C are classified as (B-2) liquid resins. As the (B-1) component, a solid thermosetting resin that can be used when forming the insulating layer of a wiring board is preferably used. Among them, solid epoxy resins and solid phenol-based resins are preferred, and solid epoxy resins are more preferred. In addition, as the (B-2) component, a liquid thermosetting resin that can be used when forming the insulating layer of a wiring board is preferably used. Among them, liquid epoxy resins are preferred. Hereinafter, each resin will be described.

[0079] Here, components such as phenol-based resins, naphthalene-based resins, benzoxazine-based resins, active ester-based resins, cyanate ester-based resins, carbodiimide-based resins, amine-based resins, and acid anhydride-based resins that can react with epoxy resins to cure the resin composition are sometimes collectively referred to as "curing agents".

[0080] Examples of epoxy resins include, for example: glycidyl (Glycirol) 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; triphenol 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, etc. epoxy resins having a condensed ring structure; glycidylamine 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; epoxy resins containing a spiro ring; cyclohexanedimethanol type epoxy resins; trimethylol type epoxy resins; tetraphenylethane type epoxy resins; glycidyl ether type aliphatic epoxy resins, etc. Epoxy resins can be used alone or in combination of two or more. The solid epoxy resin as the (B-1) component is preferably a biphenyl type epoxy resin. In addition, the liquid epoxy resin as the (B-2) component is preferably one or more selected from dicyclopentadiene type epoxy resins, bisphenol A type epoxy resins, and bisphenol F type epoxy resins.

[0081] The solid epoxy resin as the component (B-1) preferably contains a solid epoxy resin having two or more epoxy groups in one molecule. In addition, the solid epoxy resin preferably has an aromatic structure, and when two or more solid epoxy resins are used, it is more preferable that at least one has an aromatic structure. The aromatic structure refers to a chemical structure that is generally defined as aromatic, and also includes polycyclic aromatics and aromatic heterocycles. With respect to 100% by mass of the non-volatile components of the solid epoxy resin, the proportion of the epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

[0082] Regarding the solid epoxy resin as the component (B-1), naphthalene-type tetrafunctional epoxy resin, cresol novolac-type epoxy resin, dicyclopentadiene-type epoxy resin, triphenol-type epoxy resin, naphthol-type epoxy resin, biphenyl-type epoxy resin, naphthyl ether-type epoxy resin, anthracene-type epoxy resin, bisphenol A-type epoxy resin, and tetraphenylethane-type epoxy resin are preferred. Naphthalene-type tetrafunctional epoxy resin, naphthol-type epoxy resin, and biphenyl-type epoxy resin are more preferred. Further, biphenyl-type epoxy resin is particularly 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 novolac-type epoxy resin), "N-695" (cresol novolac-type epoxy resin), "HP-7200" (dicyclopentadiene-type epoxy resin), "HP-7200HH", "HP-7200H", "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthyl ether-type epoxy resin) manufactured by DIC Corporation; "EPPN-502H" (triphenol-type epoxy resin), "NC7000L" (naphthol novolac-type epoxy resin), "NC3000H", "NC3000", "NC3000L", "NC3100" (biphenyl-type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "ESN475V" (naphthalene-type epoxy resin), "ESN485" (naphthol novolac-type epoxy resin) manufactured by Nippon Steel Chemical & Material Co., Ltd.; "YX4000H", "YL6121" (biphenyl-type epoxy resin), "YX4000HK" (xylenol-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), etc. manufactured by Mitsubishi Chemical Corporation. They can be used alone or in combination of two or more.

[0083] The liquid epoxy resin as the component (B-2) preferably contains a liquid epoxy resin having two or more epoxy groups in one molecule. In addition, the liquid epoxy resin preferably has an aromatic structure. When using two or more liquid epoxy resins, it is more preferred that at least one has an aromatic structure. With respect to 100% by mass of the non-volatile component of the liquid epoxy resin, the proportion of the epoxy resin having two or more epoxy groups in one molecule is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

[0084] Regarding the liquid epoxy resin as the (B-2) component, glycidyloxy-type epoxy resins, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol AF-type epoxy resins, naphthalene-type epoxy resins, glycidyl ester-type epoxy resins, glycidyl amine-type epoxy resins, phenol novolac-type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexanedimethanol-type epoxy resins, and epoxy resins having a butadiene structure are preferred, and glycidyloxy-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; "JER-630", "JER-630LSD" manufactured by Mitsubishi Chemical Corporation, "ED-523T" (glycidyloxy-type epoxy resin (Adeka Glycirol)), "EP-3980S" (glycidyl amine-type epoxy resin), "EP-4088S" (dicyclopentadiene-type epoxy resin) manufactured by ADEKA Corporation; "ZX1059" (a mixture of bisphenol A-type epoxy resin and bisphenol F-type epoxy resin) manufactured by Nippon Steel & Sumikin Chemical 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. They can be used alone or in combination of two or more.

[0085] The epoxy equivalent of the epoxy resin is preferably 50 g / eq. to 5000 g / eq., more preferably 50 g / eq. to 3000 g / eq., further preferably 80 g / eq. to 2000 g / eq., and even more preferably 110 g / eq. to 1000 g / eq. By being in the above range, a magnetic layer with a sufficient crosslink density of the cured product and a small surface roughness can be formed. It should be noted that the epoxy equivalent can be measured in accordance with JIS K7236 and is the mass of the resin containing 1 equivalent of epoxy groups.

[0086] The weight-average molecular weight of the epoxy resin is preferably from 100 to 5000, more preferably from 250 to 3000, and still more preferably from 400 to 1500. Herein, the weight-average molecular weight of the epoxy resin is the weight-average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC).

[0087] As the phenol resin and naphthalene resin, from the viewpoints of heat resistance and water resistance, those having a novolac structure are preferred. Further, from the viewpoint of adhesion to the conductor layer, nitrogen-containing phenol resins, naphthol resins, naphthol aralkyl types, and solid phenol resins containing a triazine skeleton are preferred, and naphthol aralkyl types are more preferred.

[0088] Specific examples of the phenol resin and naphthalene resin include, for example, "MEH-7700", "MEH-7810", "MEH-7851" manufactured by Meiko Kasei Co., Ltd., "NHN", "CBN", "GPH" manufactured by Nippon Kayaku Co., Ltd., "SN170", "SN180", "SN190", "SN475", "SN485", "SN495", "SN375", "SN395" manufactured by Nippon Steel Chemical & Material Co., Ltd., "LA-7052", "LA-7054", "LA-1356", "LA-3018", "EXB-6000" manufactured by DIC Corporation, etc.

[0089] 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, resins having two or more highly reactive ester groups in one molecule, such as phenolic esters, thiophenolic esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, are preferred. 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 preferred, and an active ester resin obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound is more preferred.

[0090] 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.

[0091] Examples of the phenol compound or naphthol compound include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalin, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, pyrogallol, dicyclopentadiene-type diphenol compound, phenol novolak resin, etc. Here, the "dicyclopentadiene-type diphenol compound" means a diphenol compound obtained by condensing two molecules of phenol on one molecule of dicyclopentadiene.

[0092] Preferred specific examples of the active ester resin include: an active ester resin containing a dicyclopentadiene-type diphenol structure, an active ester resin containing a naphthalene structure, an active ester resin containing an acetylated product of phenol novolak resin, and an active ester resin containing a benzoylated product of phenol novolak resin. Among them, an active ester resin containing a naphthalene structure and an active ester resin containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" means a divalent structural unit formed by phenylene-dicyclopentylene-phenylene.

[0093] Examples of commercially available products of the active ester resin include: "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T", "HPC-8000H-65TM", "EXB-8000L-65TM" (manufactured by DIC Corporation) as an active ester resin containing a dicyclopentadiene-type diphenol structure; "EXB9416-70BK", "EXB-8150-65T" (manufactured by DIC Corporation) as an active ester resin containing a naphthalene structure; "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester resin containing an acetylated product of phenol novolak resin; "YLH1026" (manufactured by Mitsubishi Chemical Corporation) as an active ester resin containing a benzoylated product of phenol novolak resin; "DC808" (manufactured by Mitsubishi Chemical Corporation) as an active ester resin that is an acetylated product of phenol novolak resin; "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), "YLH1048" (manufactured by Mitsubishi Chemical Corporation) as an active ester resin that is a benzoylated product of phenol novolak resin; and so on.

[0094] As for the phenol resin and naphthol resin, from the viewpoints of heat resistance and water resistance, a novolak structure is preferred. In addition, from the viewpoint of the adhesion to the conductor layer, a nitrogen-containing phenol curing agent is preferred, and a phenol resin containing a triazine skeleton is more preferred.

[0095] As specific examples of phenol-based resins and naphthol-based resins, for example, "MEH-7700", "MEH-7810", "MEH-7851" manufactured by Meiwafosis 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 & Sumikin Chemical Co., Ltd., "TD-2090", "LA-7052", "LA-7054", "LA-1356", "LA-3018-50P", "EXB-9500" manufactured by DIC Corporation, etc. can be cited.

[0096] As specific examples of benzoxazine-based resins, "JBZ-OD100" (benzoxazine ring equivalent: 218), "JBZ-OP100D" (benzoxazine ring equivalent: 218), "ODA-BOZ" (benzoxazine ring equivalent: 218) manufactured by JFE Chemical Corporation can be cited; "P-d" (benzoxazine ring equivalent: 217), "F-a" (benzoxazine ring equivalent: 217) manufactured by Shikoku Kasei Kogyo Co., Ltd.; "HFB2006M" (benzoxazine ring equivalent: 432) manufactured by Showa Highpolymer Co., Ltd., etc.

[0097] As cyanate ester-based resins, for example, difunctional cyanate ester resins such as bisphenol A dicyanate, polyphenol cyanate, oligomeric (3-methylidene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylenediphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanatephenyl)propane, 1,1-bis(4-cyanatephenyl)methane, bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanatephenyl-1-(methylethylidene))benzene, bis(4-cyanatephenyl) sulfide, and bis(4-cyanatephenyl) ether can be cited; polyfunctional cyanate ester resins derived from phenol novolac resins, cresol novolac resins, etc.; prepolymers obtained by triazine formation of a part of these cyanate ester resins. As specific examples of cyanate ester-based resins, "PT30" and "PT60" (phenol novolac type polyfunctional cyanate ester resins), "ULL-950S" (polyfunctional cyanate ester resin), "BA230", "BA230S75" (prepolymer in which a part or all of bisphenol A dicyanate is triazine-formed to form a trimer) manufactured by Lonza Japan Co., Ltd., etc. can be cited.

[0098] As specific examples of the carbodiimide-based resin, CARBODILITE (registered trademark) V-03 (carbodiimide group equivalent: 216), V-05 (carbodiimide group equivalent: 262), V-07 (carbodiimide group equivalent: 200); V-09 (carbodiimide group equivalent: 200) manufactured by Nisshinbo Chemical Inc.; Stabaxol (registered trademark) P (carbodiimide group equivalent: 302) manufactured by Rhein Chemie can be cited.

[0099] As the amine-based resin, resins having one or more amino groups in one molecule can be cited, and examples thereof include aliphatic amines, polyether amines, alicyclic amines, aromatic amines, etc. Among them, from the viewpoint of exerting the effects expected by 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. As specific examples of the amine-based curing agent, 4,4'-methylenebis(2,6-dimethylaniline), diphenyl diaminosulfone, 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. can be cited. The amine-based resin can be a commercially available product, and examples thereof include "KAYABOND C-200S", "KAYABOND C-100", "KAYAHARD A-A", "KAYAHARDA-B", "KAYAHARDA-S" manufactured by Nippon Kayaku Co., Ltd., "Epicure (エピキュア) W" manufactured by Mitsubishi Chemical Corporation, etc.

[0100] As the acid anhydride resin, resins having one or more acid anhydride groups in one molecule can be cited. 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, naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, 3,3'-4,4'-diphenylsulfonetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, ethylene glycol bis(trimellitate), and polymer-type acid anhydrides such as styrene-maleic resin obtained by copolymerizing styrene and maleic acid.

[0101] When an epoxy resin and a curing agent are contained as the component (B), the amount ratio of the epoxy resin to all the curing agents is preferably in the range of 1:0.01 to 1:5, more preferably 1:0.5 to 1:3, and further preferably 1:1 to 1:2, based on the ratio of [total number of epoxy groups of the epoxy resin]:[total number of reactive groups of the curing agent]. Here, the so-called "number of epoxy groups of the epoxy resin" means the value obtained by adding up all the values obtained by dividing the mass of the non-volatile components of the solid epoxy resin and the liquid epoxy resin present in the resin composition by the epoxy equivalent. In addition, the so-called "number of active groups of the curing agent" means the value obtained by adding up all the values obtained by dividing the mass of the non-volatile components of the curing agent present in the resin composition by the active group equivalent.

[0102] Regarding the content of the (B-1) solid resin, from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components in the resin composition are set to 100% by mass, it is preferably 0.5% by mass or more, more preferably 1% by mass or more, and further preferably 1.5% by mass or more. The upper limit is not particularly limited as long as the effects of the present invention can be exhibited, and it is preferably 10% by mass or less, more preferably 8% by mass or less, and further preferably 5% by mass or less.

[0103] Regarding the content of the (B-2) liquid resin, from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components in the resin composition are set to 100% by mass, it is preferably 1% by mass or more, more preferably 5% by mass or more, and further preferably 10% by mass or more. The upper limit is not particularly limited as long as the effects of the present invention can be exhibited, and it is preferably 25% by mass or less, more preferably 20% by mass or less, and further preferably 15% by mass or less.

[0104] Regarding the content of the (B) resin, from the viewpoint of significantly obtaining the effects of the present invention, when the non-volatile components in the resin composition are set to 100% by mass, it is preferably 1% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more. There is no particular limitation on the upper limit as long as the effects of the present invention can be exhibited, and it is preferably 30% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass or less.

[0105] <(C) Curing accelerator with a melting point of 120°C or higher and 245°C or lower>

[0106] The resin composition contains a curing accelerator with a melting point of 120°C or higher and 245°C or lower as the (C) component. Generally, although the curing accelerator does not react with the (B) resin, it promotes the curing of the (B) resin. By containing the (C) curing accelerator with a melting point of 120°C or higher and 245°C or lower in the resin composition, not only the curing of the (B) resin is effectively carried out, but also the stain resistance and storage stability are excellent, and the occurrence of swelling after reflow soldering can be suppressed.

[0107] Regarding the melting point of the (C) component, from the viewpoint of improving storage stability, it is 120°C or higher, preferably 140°C or higher, more preferably 160°C or higher, and still more preferably 180°C or higher. For the upper limit, from the viewpoints of improving stain resistance and adhesion and suppressing the occurrence of swelling after reflow soldering, it is 245°C or lower, preferably 220°C or lower, more preferably 210°C, and still more preferably 200°C or lower. The melting point in this specification is a value measured using a differential scanning calorimeter and heating from room temperature (25°C) to 500°C at 20°C / min.

[0108] (C) component can use a curing accelerator with a melting point of 120°C or higher and 245°C or lower. As such a curing accelerator, those having a cyclic structure are preferred. As the cyclic structure, a cyclic group containing an alicyclic structure and a cyclic group containing an aromatic ring structure can be cited. Among them, from the viewpoint of significantly obtaining the desired effects of the present invention, a cyclic group containing an aromatic ring structure is preferred.

[0109] From the viewpoint of significantly obtaining the desired effects of the present invention, the cyclic structure is preferably a 3-membered ring or more, more preferably a 4-membered ring or more, still more preferably a 5-membered ring or more, preferably a 20-membered ring or less, more preferably a 15-membered ring or less, and still more preferably a 10-membered ring or less. In addition, as the cyclic structure, it can be a monocyclic structure or a polycyclic structure.

[0110] For the rings in the cyclic structure, in addition to carbon atoms, heteroatoms can also be used to form the ring skeleton. As the heteroatoms, for example, an oxygen atom, a sulfur atom, a nitrogen atom, etc. can be mentioned, and a nitrogen atom is preferred. One heteroatom may be present in the ring constituting the cyclic structure, or two or more heteroatoms may be present in the ring constituting the cyclic structure.

[0111] Examples of the alicyclic structure include a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, etc.

[0112] Examples of the aromatic ring constituting the aromatic ring structure include aromatic heterocycles such as a benzene ring, a naphthalene ring, an anthracene ring, a triazine ring, etc., a benzene ring, a pyridine ring, an imidazole ring, a triazine ring are preferred, and a triazine ring is more preferred. Examples of the triazine ring include a 1,3,5-triazine ring, a 1,2,3-triazine ring, a 1,2,4-triazine ring, a 1,3,5-triazine ring, etc., and a 1,3,5-triazine ring is preferred.

[0113] The ring in the cyclic structure may have a substituent. Examples of such a substituent include, for example, a halogen atom, an alkyl group, an alkoxy group, an aryl group, an arylalkyl group, a silyl group, an acyl group, an acyloxy group, a carboxyl group, a sulfo group, a cyano group, a nitro group, a hydroxyl group, a mercapto group, an oxo group, etc.

[0114] The component (C) can be a commercially available product, or two or more kinds can be used in combination. Specific examples of the commercially available component (C) that can be used include "C11Z-A" (melting point 187 to 195 °C), "2E4MZ-A" (melting point 215 to 225 °C), "C11Z-CNS" (melting point 123 to 129 °C), "2PZCNS-PW" (melting point 175 to 183 °C), "VT" (melting point 239 to 241 °C), "MAVT" (melting point 170 °C or higher) manufactured by Shikoku Kasei Co., Ltd. etc. The component (C) can be used alone, or two or more kinds can be used in combination.

[0115] Regarding the content of the component (C), from the viewpoints of improving stain resistance and storage stability and suppressing the occurrence of swelling after reflow soldering, when the non-volatile component in the resin composition is 100% by mass, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, and the upper limit is preferably 10% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less.

[0116] When the content of the component (C) when the non-volatile component in the resin composition is 100% by mass is denoted as c1, as b1 / c1, from the viewpoint of significantly obtaining the effects of the present invention, it is preferably 0.1 or more, more preferably 0.3 or more, further preferably 0.5 or more, preferably 5 or less, more preferably 4 or less, further preferably 3 or less.

[0117] As b2 / c1, from the viewpoint of significantly obtaining the effects of the present invention, it is preferably 1 or more, more preferably 3 or more, further preferably 5 or more, preferably 20 or less, more preferably 15 or less, and further preferably 10 or less.

[0118] When the content of the component (B) is denoted as b3 when the non-volatile components in the resin composition are 100% by mass, as b3 / c1, from the viewpoint of significantly obtaining the effects of the present invention, it is preferably 1 or more, more preferably 3 or more, further preferably 5 or more, preferably 20 or less, more preferably 15 or less, and further preferably 10 or less.

[0119] <(D) Other additives>

[0120] If necessary, the resin composition may further contain (D) other additives. Examples of the other additives include thermoplastic resins, curing retarders such as triethyl borate for improving storage stability, dispersants, inorganic fillers (excluding substances belonging to magnetic powders), curing accelerators (excluding substances belonging to the component (C)), flame retardants, organic fillers, organometallic compounds such as organic copper compounds, organic zinc compounds, and organic cobalt compounds, and resin additives such as thickeners, defoamers, leveling agents, adhesion-imparting agents, and colorants.

[0121] Regarding the content of the solvent contained in the above resin composition, relative to the total mass of the resin composition, it is preferably less than 1.0% by mass, more preferably 0.8% by mass or less, further preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less. The lower limit is not particularly limited and is 0.001% by mass or more, or it may not contain any. By making the content of the organic solvent within the above range, the occurrence of voids can be suppressed, and in addition, the processability and operability can also be excellent.

[0122] <Manufacturing method of resin composition>

[0123] For the resin composition, for example, it can be manufactured by a method of stirring the compounding components using a stirring device such as a three-roll mill or a rotary mixer.

[0124] <Physical properties, etc. of resin composition>

[0125] In the resin composition, component (B-1) and component (B-2) are contained in a specified ratio, and further component (C) is contained in combination. Therefore, it generally exhibits excellent storage stability. The viscosity A of the resin composition at 25 ± 2°C immediately after production is measured using an E-type viscometer. Next, the viscosity B of the resin composition at 25 ± 2°C after standing for 3 days is measured using an E-type viscometer, and viscosity A / viscosity B is calculated. Viscosity A / viscosity B is preferably 1.0 or more and preferably 1.5 or less. The evaluation of storage stability can be measured according to the method described in the following examples.

[0126] The cured product of the resin composition of the present invention exhibits the characteristic of a low rough surface change rate. That is, a magnetic layer excellent in stain resistance and adhesion to the conductor layer is formed. The rough surface change rate is preferably 1.7 or less, more preferably 1.6 or less, and still more preferably 1.5 or less. The lower limit is not particularly limited and can be 1.0 or more, etc. The rough surface change rate can be measured according to the method described in the following examples.

[0127] The cured product of the resin composition of the present invention exhibits the characteristic of suppressing swelling after reflow soldering. That is, a magnetic layer excellent in reflow soldering resistance (reflow soldering tolerance) is formed. The evaluation of whether there is swelling after reflow soldering can be measured according to the method described in the following examples.

[0128] The resin composition exhibits the characteristic of low viscosity. Therefore, it has the characteristic that the resin composition is paste-like (paste-like resin composition) and can be suitably used as a resin composition for via filling.

[0129] [Magnetic sheet]

[0130] The magnetic sheet includes a support and a resin composition layer formed of the resin composition of the present invention provided on the support.

[0131] From the viewpoint of thinning, the thickness of the resin composition layer is preferably 250 μm or less, more preferably 200 μm or less. The lower limit of the thickness of the resin composition layer is not particularly limited and can generally be 5 μm or more, 10 μm or more, etc.

[0132] Examples of the support include a film formed of a plastic material, a metal foil, and a release paper, and preferably a film formed of a plastic material and a metal foil.

[0133] When using a film formed of a plastic material as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes simply referred to as "PET"), polyethylene naphthalate (hereinafter sometimes simply referred to as "PEN"), polycarbonate (hereinafter sometimes simply referred to as "PC"), acrylic polymers such as polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. Among them, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0134] When using a metal foil as the support, examples of the metal foil include copper foil, aluminum foil, etc., and copper foil is preferred. As the copper foil, a foil formed of single metal of copper can be used, or a foil formed of an alloy of copper and other metals (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) can be used.

[0135] For the support, the surface joined to the resin composition layer can be subjected to matting treatment or corona treatment.

[0136] In addition, as the support, a support with a release layer having a release layer on the surface joined to the resin composition layer can be used. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from alkyd resins, polyolefin resins, polyurethane resins, and silicone resins. The support with a release layer can use commercially available products, and examples include "PET501010", "SK-1", "AL-5", "AL-7" of Lintec Corporation, which are PET films having a release layer mainly composed of an alkyd resin-based release agent; "Lumirror T60" of Toray Industries, Inc.; "Purex" of Teijin Limited; "Unipeel" of UNITIKA Ltd., etc.

[0137] The thickness of the support is not particularly limited, and preferably ranges from 5 μm to 75 μm, more preferably ranges from 10 μm to 60 μm. It should be noted that when using a support with a release layer, the thickness of the entire support with a release layer is preferably in the above range.

[0138] In the magnetic sheet, a protective film selected according to the support can be further laminated on the surface of the resin composition layer that is not joined to the support (that is, the surface on the opposite side of the support). The thickness of the protective film is not particularly limited, for example, it is 1 μm to 40 μm. By laminating the protective film, it is possible to suppress the adhesion of dust, etc. on the surface of the resin composition layer or to cause damage on the surface of the resin composition layer. The magnetic sheet can be wound into a roll for storage. When the magnetic sheet has a protective film, it can be used by peeling off the protective film.

[0139] A magnetic sheet can be manufactured, for example, by coating a resin composition on a support using a die coater or the like to form a resin composition layer. If necessary, a resin varnish dissolved in an organic solvent can be prepared and coated on the support. When using an organic solvent, drying can be carried out as needed after coating.

[0140] Drying can be carried out by known methods such as heating and blowing hot air. The drying conditions are not particularly limited, and drying is carried out such that the content of the organic solvent in the resin composition layer becomes 10% by mass or less, preferably 5% by mass or less. Although it varies depending on the components contained in the resin composition, a resin composition layer can be formed by drying at 50°C to 150°C for 3 minutes to 10 minutes.

[0141] The magnetic sheet can be wound into a roll for storage. When the magnetic sheet has a protective film, it can be used by peeling off the protective film.

[0142] [Circuit Board and Method for Manufacturing the Same]

[0143] 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 aforementioned through holes. In addition, the circuit board of the second embodiment includes: a magnetic layer formed from a cured product of the resin composition layer of the magnetic sheet. Hereinafter, the first embodiment and the second embodiment of the method for manufacturing a circuit board will be described. However, the method for manufacturing a circuit board according to the present invention is not limited to the first embodiment and the second embodiment exemplified below.

[0144] <First Embodiment>

[0145] The circuit board of the first embodiment can be manufactured, for example, by a manufacturing method including the following steps (1) to (5). In the first embodiment, it is preferable to form a magnetic layer using the resin composition, and more preferably to form a magnetic layer using a paste-like resin composition;

[0146] (1) A step of filling a resin composition into the through holes of a substrate having through holes,

[0147] (2) A step of thermally curing the resin composition to obtain a cured product,

[0148] (3) A step of grinding the surface of the cured product or the resin composition,

[0149] (4) A step of roughening the cured product, and

[0150] (5) A step of forming a conductor layer on the roughened surface of the cured product;

[0151] The manufacturing method of the circuit board of the present invention can be carried out in the order of steps (1) to (5), or step (2) can be carried out after step (3).

[0152] <Step (1)>

[0153] When carrying out step (1), it may include the step of preparing a resin composition. The resin composition is as described above.

[0154] In addition, when carrying out step (1), as Figure 1 shown in an example, it may include the step of preparing a core substrate 10, and the core substrate 10 includes: a support substrate 11, and a first metal layer 12 and a second metal layer 13 formed of a metal such as copper foil on both surfaces of the support substrate 11. As an example of the material of the support substrate 11, insulating substrates such as glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates can be cited. As an example of the material of the first metal layer and the second metal layer, copper foil with a carrier, the material of the conductor layer described later, etc. can be cited.

[0155] In addition, as Figure 2 shown in an example, it may include the step of forming a through hole 14 in the core substrate 10. The through hole 14 can be formed, for example, by a drill, laser irradiation, plasma irradiation, etc. Specifically, a through hole can be formed in the core substrate 10 by using a drill or the like to form the through hole 14.

[0156] The formation of the through hole 14 can be carried out using a commercially available drill device. As a commercially available drill device, for example, "ND-1S211" manufactured by Hitachi Via Mechanics Co., Ltd. can be cited.

[0157] After the through hole 14 is formed in the core substrate 10, as Figure 3 shown in an example, it may include: performing a roughening treatment on 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.

[0158] As the aforementioned roughening treatment, any of dry and wet roughening treatments can be carried out. As an example of the dry roughening treatment, plasma treatment, etc. can be cited. In addition, as an example of the wet roughening treatment, a method of sequentially performing a swelling treatment using a swelling liquid, a roughening treatment using an oxidant, and a neutralization treatment using a neutralizing liquid can be cited.

[0159] The plating layer 20 can be formed by a plating method, and the steps of forming the plating layer 20 by the plating method are the same as those of forming the conductor layer in step (5) described later.

[0160] After preparing the core substrate 10, asFigure 4 As shown in one example, the resin composition 30a is filled into the through hole 14. The filling can be performed by, for example, a printing method. Examples of the printing method include: a method of printing the resin composition 30a into the through hole 14 through a squeegee, a method of printing the resin composition 30a through a cartridge, a method of performing mask printing to print the resin composition 30a, a roll coating method, an inkjet method, and the like.

[0161] <Process (2)>

[0162] In process (2), after filling the resin composition 30a into the through hole 14, the resin composition 30a is thermally cured, and as Figure 5 shown in one example, a cured product layer (magnetic layer) 30 is formed in the through hole 14. The thermal curing conditions of the resin composition 30a vary depending on the composition or type of the resin composition 30a. The curing temperature is preferably 120 °C or higher, more preferably 130 °C or higher, further preferably 150 °C or higher, preferably 245 °C or lower, more preferably 220 °C or lower, and further preferably 200 °C or lower. The curing time of the resin composition 30a is preferably 5 minutes or longer, more preferably 10 minutes or longer, further preferably 15 minutes or longer, preferably 120 minutes or shorter, more preferably 100 minutes or shorter, and further preferably 90 minutes or shorter.

[0163] As the degree of curing of the magnetic layer 30 in process (2), it is preferably 80% or higher, more preferably 85% or higher, and further preferably 90% or higher. The degree of curing can be measured, for example, using a differential scanning calorimetry device.

[0164] Before thermally curing the resin composition 30a, a preheating treatment of heating the resin composition 30a at a temperature lower than the curing temperature can be performed. For example, before thermally curing the resin composition 30a, the resin composition 30a can be preheated at a temperature generally of 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 generally 5 minutes or longer (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes).

[0165] When step (3) is carried out after step (2), after step (2) and before step (3), for the purpose of further improving the degree of curing of the magnetic layer, etc., heat treatment can be carried out as required. The temperature in the aforementioned heat treatment can be carried out according to the above-mentioned curing temperature, preferably 120 °C or higher, more preferably 130 °C or higher, further preferably 150 °C or higher, preferably 245 °C or lower, more preferably 220 °C or lower, and further preferably 200 °C or lower. The heat treatment time is preferably 5 minutes or more, more preferably 10 minutes or more, further preferably 15 minutes or more, preferably 90 minutes or less, more preferably 70 minutes or less, and further preferably 60 minutes or less.

[0166] In addition, when step (3) is carried out before step (2), before step (3), preheating treatment can be carried out by heating at a temperature lower than the curing temperature of the resin composition. The temperature in the aforementioned preheating treatment is preferably 100 °C or higher, more preferably 110 °C or higher, further preferably 120 °C or higher, preferably 245 °C or lower, more preferably 220 °C or lower, and further preferably 200 °C or lower. The heat treatment time is preferably 5 minutes or more, more preferably 10 minutes or more, further preferably 15 minutes or more, preferably 90 minutes or less, more preferably 70 minutes or less, and further preferably 60 minutes or less.

[0167] <Step (3)>

[0168] In step (3), as Figure 6 shown in an example, the excess magnetic layer 30 protruding or adhering from the core substrate 10 is removed by grinding to perform planarization. As the grinding method, a method capable of grinding the excess magnetic layer 30 protruding or adhering from the core substrate 10 can be used. As such a grinding method, for example, polishing and abrasive belt grinding can be cited. As a commercially available polishing device, "NT-700IM" manufactured by Ishii Marking Co., Ltd. can be cited.

[0169] Regarding the arithmetic mean roughness (Ra) of the grinding surface of the magnetic layer (after the thermal curing of the magnetic layer), from the viewpoint of improving the adhesion with the plating layer, it is preferably 300 nm or more, more preferably 350 nm or more, and further preferably 400 nm or more. The upper limit is preferably 1000 nm or less, more preferably 900 nm or less, and further preferably 800 nm or less. The surface roughness (Ra) can be measured using a non-contact surface roughness meter, for example.

[0170] When step (3) is carried out after step (2), after step (2) and before step (3), for the purpose of further improving the degree of curing of the magnetic layer, etc., heat treatment can be carried out as required. The temperature in the aforementioned heat treatment can be carried out according to the above-mentioned curing temperature, preferably 120 °C or higher, more preferably 130 °C or higher, further preferably 150 °C or higher, preferably 245 °C or lower, more preferably 220 °C or lower, and further preferably 200 °C or lower. The heat treatment time is preferably 5 minutes or longer, more preferably 10 minutes or longer, further preferably 15 minutes or longer, preferably 90 minutes or shorter, more preferably 70 minutes or shorter, and further preferably 60 minutes or shorter.

[0171] In addition, when step (3) is carried out before step (2), before step (3), preheating treatment can be carried out by heating at a temperature lower than the curing temperature of the resin composition. The temperature in the aforementioned preheating treatment is preferably 100 °C or higher, more preferably 110 °C or higher, further preferably 120 °C or higher, preferably 245 °C or lower, more preferably 220 °C or lower, and further preferably 200 °C or lower. The heat treatment time is preferably 5 minutes or longer, more preferably 10 minutes or longer, further preferably 15 minutes or longer, preferably 90 minutes or shorter, more preferably 70 minutes or shorter, and further preferably 60 minutes or shorter.

[0172] <Step (4)>

[0173] In step (4), a roughening treatment (excluding contamination treatment) is carried out on the surface ground in step (3). The steps and conditions of the roughening process are not particularly limited, and known steps and conditions commonly used in the manufacturing method of a multilayer printed wiring board can be adopted. As the roughening process, for example, the first magnetic layer 32 can be roughened by sequentially carrying out a swelling treatment using a swelling liquid, a roughening treatment using an oxidant, and a neutralization treatment using a neutralization liquid.

[0174] The swelling liquid that can be used in the roughening process is not particularly limited, and examples thereof include an alkali solution and a surfactant solution, and an alkali solution is preferred. Regarding the alkali solution as the swelling liquid, sodium hydroxide solution and potassium hydroxide solution are more preferred. As commercially available swelling liquids, for example, "Swelling Dip Securiganth P" and "Swelling Dip Securiganth SBU" manufactured by Atotech Japan Co., Ltd. can be cited.

[0175] The swelling treatment using the swelling liquid is not particularly limited. For example, it can be carried out by immersing the core substrate 20 provided with the first magnetic layer 32 in the swelling liquid at 30°C to 90°C for 1 minute to 20 minutes. From the viewpoint of suppressing the swelling of the resin constituting the first magnetic layer 32 to an appropriate level, it is preferable to immerse the first magnetic layer 32 in the swelling liquid at 40°C to 80°C for 5 minutes to 15 minutes.

[0176] There is no particular limitation on the oxidant that can be used in the roughening treatment using an oxidant. For example, an alkaline permanganic acid solution prepared by dissolving potassium permanganate or sodium permanganate in an aqueous sodium hydroxide solution can be cited. The roughening treatment using an oxidant such as an alkaline permanganic acid solution is preferably carried out by immersing the first magnetic layer 32 in the oxidant solution heated to 60°C to 80°C for 10 minutes to 30 minutes. In addition, the concentration of the permanganate in the alkaline permanganic acid solution is preferably 5% by mass to 10% by mass. As commercially available oxidants, for example, alkaline permanganic acid solutions such as "Concentrate Compact P" and "Dosing Solution Securiganth P" manufactured by Atotech Japan Co., Ltd. can be cited.

[0177] As the neutralizing liquid that can be used in the neutralization treatment, an acidic aqueous solution is preferred. As commercially available products, for example, "Reduction Solution Securiganth P" manufactured by Atotech Japan Co., Ltd. can be cited. The neutralization treatment using the neutralizing liquid can be carried out by immersing the treated surface that has undergone the roughening treatment using the oxidant solution in the neutralizing liquid at 30°C to 80°C for 5 minutes to 30 minutes. From the viewpoint of operability and the like, a method of immersing the first magnetic layer 32 that has undergone the roughening treatment using the oxidant solution in the neutralizing liquid at 40°C to 70°C for 5 minutes to 20 minutes is preferred.

[0178] As the arithmetic mean roughness (Ra) after the roughening treatment of the magnetic layer, from the viewpoint of improving the adhesion with the plating layer, it is preferably 300 nm or more, more preferably 350 nm or more, and further preferably 400 nm or more. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and further preferably 1000 nm or less. The surface roughness (Ra) can be measured using, for example, a non-contact surface roughness meter.

[0179] <Process (5)>

[0180] In process (5), as Figure 7 shown in an example, a conductor layer 40 is formed on the polished surface of the magnetic layer 30 and the core substrate. Further, after forming the conductor layer 40, as Figure 8As shown in one example, a part of the conductor layer 40, the first metal layer 12, the second metal layer 13, and the plating layer 20 can be removed by processing such as etching to form a patterned conductor layer 41. Figure 7 In [description of Figure Figure 7 ], the conductor layer 40 is formed on both sides of the core substrate 10, but the conductor layer 40 may also be formed only on one side of the core substrate 10.

[0181] Examples of the method for forming the conductor layer include, for example, plating methods, sputtering methods, evaporation plating methods, etc. Among them, a plating method is preferred. In a preferred embodiment, it is coated 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 for the conductor layer include, for example: single metals such as gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, indium, etc.; alloys of two or more metals selected from gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. Among them, from the viewpoints of versatility, cost, ease of patterning, etc., it is preferable to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or nickel-chromium alloy, copper-nickel alloy, copper-titanium alloy, and more preferably to use chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver or copper, or nickel-chromium alloy, and further preferably to use copper.

[0182] Here, an example of an embodiment of forming a patterned conductor layer on the ground surface of the cured product will be described in detail. An electroless plating seed layer is formed on the ground surface of the cured product by electroless plating. Next, an electroplated layer is formed on the formed electroless plating seed layer, and if necessary, the unnecessary electroless plating seed layer is removed by processing such as etching, and a conductor layer having a desired wiring pattern can be formed. After the conductor layer is formed, an annealing treatment may be performed as needed for the purpose of improving the peel strength of the conductor layer, etc. The annealing treatment can be performed, for example, by heating the circuit board at 150 to 200 °C for 20 to 90 minutes.

[0183] From the viewpoint of thinning, the thickness of the patterned conductor layer is preferably 70 μm or less, more preferably 60 μm or less, further preferably 50 μm or less, still further preferably 40 μm or less, and particularly preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The lower limit is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 5 μm or more.

[0184] <Second Embodiment>

[0185] 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 use a magnetic sheet to form the magnetic layer. Hereinafter, the second embodiment of the manufacturing method of the product substrate will be described. The description of the content repeated with the description of the first embodiment will be appropriately omitted.

[0186] The circuit board of the second embodiment is manufactured, for example, by a manufacturing method including the following steps (A) to (D):

[0187] (A) A step of laminating a magnetic sheet on an inner layer substrate in such a manner that a resin composition layer is joined to the inner layer substrate, thereby forming a magnetic layer;

[0188] (B) A step of performing opening processing on the magnetic layer;

[0189] (C) A step of roughening the surface of the magnetic layer; and

[0190] (D) A step of forming a conductor layer on the polished surface of the magnetic layer.

[0191] Hereinafter, the above steps (A) to (D) in manufacturing the circuit board will be described in detail.

[0192] <Step (A)>

[0193] Step (A) is a step of laminating a magnetic sheet on an inner layer substrate in such a manner that a resin composition layer is joined to the inner layer substrate, thereby forming a magnetic layer. As one embodiment of Step (A), a magnetic sheet is laminated on an inner layer substrate in such a manner that a resin composition layer is joined to the inner layer substrate, and the resin composition layer is thermally cured, thereby forming a magnetic layer.

[0194] In Step (A), as Figure 9 shown in an example, a magnetic sheet 310 including a support 330 and a resin composition layer 320a provided on the support 330 is laminated on the inner layer substrate 200 in such a manner that the resin composition layer 320a is joined to the inner layer substrate 200.

[0195] The inner layer substrate 200 is an insulating substrate. As the material of the inner layer substrate 200, insulating substrates such as a glass epoxy substrate, a metal substrate, a polyester substrate, a polyimide substrate, a BT resin substrate, and a thermosetting polyphenylene ether substrate can be cited. The inner layer substrate 200 may be an inner layer circuit board in which wirings and the like are incorporated in its thickness.

[0196] As Figure 9 shown in an example, the inner layer substrate 200 has: a first conductor layer 420 provided on the first main surface 200a, and external terminals 240 provided on the second main surface 200b. The first conductor layer 420 may include a plurality of wirings. In the illustrated example, only the wirings of the coil-shaped conductive structure 400 constituting the inductor element are shown. The external terminals 240 are terminals for electrically connecting to an external device (not shown) and the like. The external terminals 240 may be formed as a part of the conductor layer provided on the second main surface 200b.

[0197] As the conductor material that can form the first conductor layer 420 and the external terminal 240, it is the same as the material of the conductor layer described in the "<Process (5)>" column of the first embodiment.

[0198] The first conductor layer 420 and the external terminal 240 can be a single-layer structure, or can be a multi-layer structure formed by laminating two or more single-metal layers or alloy layers made of different kinds of metals or alloys. In addition, 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.

[0199] The line width (L) / line pitch (S) ratio of the first conductor layer 420 and the external terminal 240 is not particularly limited. 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, further preferably 300 / 300 μm or less, and further more preferably 200 / 200 μm or less. The lower limit of the line width / line pitch ratio is not particularly limited. From the viewpoint of good filling of the resin composition layer into the wiring spaces, it is preferably 1 / 1 μm or more.

[0200] The inner layer substrate 200 may have a through hole 220 that penetrates the inner layer substrate 200 from the first main surface 200a to the second main surface 200b. A through hole internal wiring 220a is provided in the through hole 220. The through hole internal wiring 220a electrically connects the first conductor layer 420 and the external terminal 240.

[0201] The bonding of 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 side of the support 330. As a member for thermocompression bonding the magnetic sheet 310 to the inner layer substrate 200 (hereinafter, also referred to as "thermocompression bonding member"), for example, a heated metal plate (such as a stainless steel (SUS) end plate) or a metal roll (SUS roll) can be cited. It should be noted that it is preferable to perform pressing not by directly contacting the thermocompression bonding member with the magnetic sheet 310, but by pressing through a sheet formed of an elastic material such as heat-resistant rubber, so that the magnetic sheet 310 can fully follow the surface irregularities of the inner layer substrate 200.

[0202] The temperature during thermocompression bonding is preferably in the range of 80°C to 160°C, more preferably in the range of 90°C to 140°C, and further preferably in the range of 100°C to 120°C. The pressure during thermocompression bonding is preferably in the range of 0.098 MPa to 1.77 MPa, more preferably in the range of 0.29 MPa to 1.47 MPa. The time during thermocompression bonding is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. The bonding of the magnetic sheet and the inner layer substrate is preferably performed under a reduced pressure condition where the pressure is 26.7 hPa or less.

[0203] The bonding of the resin composition layer 320a of the magnetic sheet 310 to the inner layer substrate 200 can be carried out using a commercially available vacuum laminator. As commercially available vacuum laminators, for example, a vacuum pressure type laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko-Materials Co., Ltd., etc. can be cited.

[0204] After the bonding of the magnetic sheet 310 and the inner layer substrate 200, under normal pressure (atmospheric pressure), for example, pressing the heat-bonding member from the support side, whereby the smoothing process of the laminated magnetic sheet 310 can be carried out. The pressing conditions for the smoothing process can be set to the same conditions as the above-mentioned heat-bonding conditions for lamination. The smoothing process can be carried out using a commercially available laminator. It should be noted that lamination and the smoothing process can be continuously carried out using the above-mentioned commercially available vacuum laminator.

[0205] After laminating the magnetic sheet on the inner layer substrate, the resin composition layer is thermally cured to form a magnetic layer. As Figure 10 In an example shown, the resin composition layer 320a bonded to the inner layer substrate 200 is thermally cured to form the first magnetic layer 320.

[0206] The thermal curing conditions of the resin composition layer 320a vary depending on the composition and type of the resin composition. The curing temperature is preferably 120 °C or higher, more preferably 130 °C or higher, further preferably 150 °C or higher, preferably 245 °C or lower, more preferably 220 °C or lower, further preferably 200 °C or lower. The curing time of the resin composition layer 320a is preferably 5 minutes or longer, more preferably 10 minutes or longer, further preferably 15 minutes or longer, preferably 120 minutes or shorter, more preferably 100 minutes or shorter, further preferably 90 minutes or shorter.

[0207] The support 330 can be removed between the thermal curing in step (A) and step (B), or can be peeled off after step (B).

[0208] As the arithmetic mean roughness (Ra) before the roughening process of the magnetic layer, from the viewpoint of improving the adhesion with the plating layer, it is preferably 300 nm or more, more preferably 350 nm or more, further preferably 400 nm or more. The upper limit is preferably 1000 nm or less, more preferably 900 nm or less, further preferably 800 nm or less. The surface roughness (Ra) can be measured using, for example, a non-contact surface roughness meter.

[0209] For step (A), instead of the magnetic sheet, the resin composition can be coated on the inner layer substrate using a die coater or the like and thermally cured to form a magnetic layer.

[0210] <Process (B)>

[0211] In Process (B), as Figure 11 shown in an example, an opening process is performed on the first magnetic layer 320 to form a via hole 360. The via hole 360 serves as a path for electrically connecting the first conductor layer 420 and a second conductor layer 440 described later. For the formation of the via hole 360, depending on the composition of the resin composition used in the formation of the magnetic layer, etc., it can be implemented using, for example, a drill, laser, plasma, etc. The size and shape of the hole can be appropriately determined according to the design of the printed wiring board.

[0212] <Process (C)>

[0213] In Process (C), the surface of the magnetic layer in which the via hole is formed is roughened. As the roughening process in Process (C), it is as described in the "<Process (4)>" column of the first embodiment.

[0214] Regarding the arithmetic mean roughness (Ra) after the roughening process of the magnetic layer, from the viewpoint of improving the adhesion with the plating layer, it is preferably 300 nm or more, more preferably 350 nm or more, and further preferably 400 nm or more. The upper limit is preferably 1500 nm or less, more preferably 1200 nm or less, and further preferably 1000 nm or less. The surface roughness (Ra) can be measured using, for example, a non-contact surface roughness meter.

[0215] In Process (C), instead of the roughening process, grinding can be performed to remove the excess magnetic layer protruding or adhering from the core substrate 10 and perform planarization. As the grinding method, as described above.

[0216] <Process (D)>

[0217] In Process (D), as Figure 12 shown in an example, a second conductor layer 440 is formed on the first magnetic layer 320.

[0218] As the conductor material that can constitute the second conductor layer 440, it is the same as the material of the conductor layer described in the "<Process (5)>" column of the first embodiment.

[0219] From the viewpoint of thinning, the thickness of the second conductor layer 440 is preferably 70 μm or less, more preferably 60 μm or less, further preferably 50 μm or less, further more preferably 40 μm or less, particularly preferably 30 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less. The lower limit is preferably 1 μm or more, more preferably 3 μm or more, and further preferably 5 μm or more.

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

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

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

[0223] After the process (D), a process of forming a magnetic layer on the conductor layer can be further performed. As shown in an example described in detail later Figure 14 a second magnetic layer 340 is formed on the first magnetic layer 320 on which the second conductor layer 440 and the through-hole inner wiring 360a are formed. The second magnetic layer can be formed by the same process as the process already described.

[0224] [Inductor substrate]

[0225] 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, an inductor pattern formed of a conductor is provided at least in a part around the cured product of the resin composition. Such an inductor substrate can be applied to, for example, the inductor substrate described in Japanese Patent Application Laid-Open No. 2016-197624.

[0226] In addition, in the case of a circuit board obtained by the manufacturing method of the circuit board using the second embodiment, the inductor board has a magnetic layer and a conductive structure at least a part of which is buried in the magnetic layer, and includes an inductor element formed by the conductive structure and a part of the magnetic layer extending in the thickness direction of the magnetic layer and surrounded by the conductive structure. Here, Figure 13 FIG. Figure 13 is a schematic plan view of the inductor board incorporating the inductor element as viewed from one side in the thickness direction thereof. Figure 14 FIG. Figure 14 is a schematic diagram showing a cut end face of the inductor board cut at the position indicated by the II-II dash-dotted line shown in Figure 13 FIG. Figure 13 . Figure 15 FIG. Figure 15 is a schematic plan view for explaining the structure of the first conductor layer in the inductor board.

[0227] As Figure 13 and Figure 14 shown in an example, the circuit board 100 is a build-up wiring board having 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, having build-up magnetic layers and build-up conductor layers. In addition, the inductor board 100 includes an inner layer board 200.

[0228] It can be seen from Figure 14 that the first magnetic layer 320 and the second magnetic layer 340 constitute a magnetic portion 300 of a magnetic layer that can be regarded as an integral body. Therefore, the coil-shaped conductive structure 400 is provided in such a manner that at least a part thereof is buried in the magnetic portion 300. That is, in the inductor board 100 of the present embodiment, the inductor element is formed by the coil-shaped conductive structure 400 and a part of the magnetic portion 300, that is, a core portion, which extends in the thickness direction of the magnetic portion 300 and is surrounded by the coil-shaped conductive structure 400.

[0229] As Figure 15 shown in an example, the first conductor layer 420 includes a spiral wiring portion for forming the coil-shaped conductive structure 400 and a rectangular pad 420a electrically connected to the via inner wiring 220a. In the illustrated example, the spiral wiring portion includes a linear portion, a bent portion bent at a right angle, and a detour portion that detours at the pad 420a. In 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 from the center side to the outside thereof.

[0230] 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. Figure 13 Or Figure 14 in FIG. Figure 14 , the spiral wiring portion includes a linear portion and a bent portion bent at a right angle.Figure 13 or Figure 14 In Figure 14 , the spiral wiring portion of the second conductor layer 440 has a shape in which the overall contour is substantially rectangular and is wound clockwise from the center side to the outside thereof.

[0231] Such an inductor substrate can be used as a wiring board for mounting electronic components such as semiconductor chips, or as a (multi-layer) printed wiring board using the wiring board as an inner layer substrate. In addition, it can be used as a chip inductor component formed by singulating the wiring board, or as a printed wiring board on which the chip inductor component is surface-mounted.

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

[0233] Examples

[0234] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited by these examples. It should be noted that in the following description, for "parts" and "%" indicating amounts, unless otherwise clearly specified, they respectively refer to "parts by mass" and "mass %". It should be noted that for the melting point, a differential scanning calorimeter (DSC7000X, manufactured by Hitachi High-Tech Corporation) was used to measure the temperature from room temperature (25 °C) to 500 °C at a rate of 20 °C / min.

[0235] <Example 1>

[0236] To 80 parts by mass of soft magnetic powder a ("M05S", Fe-Mn-based ferrite, manufactured by Powdertech), 5 parts by mass of liquid resin a ("ZX-1059", a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), 5 parts by mass of liquid resin b ("EP-4088S", dicyclopentadiene type aliphatic epoxy resin, manufactured by ADEKA Corporation), 2 parts by mass of liquid resin c ("JER-630", polyfunctional epoxy resin, manufactured by Mitsubishi Chemical Corporation), 3 parts by mass of solid resin a ("NC-3000-L", biphenyl type aromatic epoxy resin, manufactured by Nippon Kayaku Co., Ltd.), and 2 parts by mass of curing accelerator a ("C11Z-A", having a melting point of 192 °C and having a triazine skeleton, manufactured by Shikoku Chemicals Corporation) were added and uniformly dispersed using a high-speed rotary mixer to obtain resin composition 1.

[0237] <Example 2>

[0238] In Example 1, the amount of the solid resin a (“NC-3000-L”, a biphenyl-type aromatic epoxy resin, manufactured by Nippon Kayaku Co., Ltd.) was changed from 3 parts by mass to 2 parts by mass. Except for the above matters, the operation was carried out in the same manner as in Example 1 to obtain Resin Composition 2.

[0239] <Example 3>

[0240] In Example 1, the amount of the solid resin a (“NC-3000-L”, a biphenyl-type aromatic epoxy resin, manufactured by Nippon Kayaku Co., Ltd.) was changed from 3 parts by mass to 5 parts by mass. Except for the above matters, the operation was carried out in the same manner as in Example 1 to obtain Resin Composition 3.

[0241] <Example 4>

[0242] In Example 1, 3 parts by mass of the solid resin a (“NC-3000-L”, a biphenyl-type aromatic epoxy resin, manufactured by Nippon Kayaku Co., Ltd.) was changed to 3 parts by mass of the solid resin b (“NC-3100”, a biphenyl-type epoxy resin, manufactured by Nippon Kayaku Co., Ltd.). Except for the above matters, the operation was carried out in the same manner as in Example 1 to obtain Resin Composition 4.

[0243] <Example 5>

[0244] In Example 1, 3 parts by mass of the solid resin a (“NC-3000-L”, a biphenyl-type aromatic epoxy resin, manufactured by Nippon Kayaku Co., Ltd.) was changed to 3 parts by mass of the solid resin c (“SN-485”, a naphthol aralkyl-type epoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd.). Except for the above matters, the operation was carried out in the same manner as in Example 1 to obtain Resin Composition 5.

[0245] <Example 6>

[0246] In Example 1,

[0247] the amount of the solid resin a (“NC-3000-L”, a biphenyl-type aromatic epoxy resin, manufactured by Nippon Kayaku Co., Ltd.) was changed from 3 parts by mass to 1.5 parts by mass, and further, 1.5 parts by mass of the solid resin c (“SN-485”, a naphthol aralkyl-type epoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd.) was used;

[0248] Except for the above matters, the operation was carried out in the same manner as in Example 1 to obtain Resin Composition 6.

[0249] <Example 7>

[0250] In Example 1, 80 parts by mass of soft magnetic powder a (“M05S”, Fe-Mn-based ferrite, manufactured by Powdertech) was changed to 80 parts by mass of soft magnetic powder b (“MZ05”, Fe-Mn-Zn-based ferrite, manufactured by Powdertech). Except for the above matters, the operation was the same as in Example 1, and resin composition 7 was obtained.

[0251] <Example 8>

[0252] In Example 1, 80 parts by mass of soft magnetic powder a (“M05S”, Fe-Mn-based ferrite, manufactured by Powdertech) was changed to 80 parts by mass of soft magnetic powder c (“AW2-08”, Fe-Si-based ferrite, manufactured by Epson Atmix). Except for the above matters, the operation was the same as in Example 1, and resin composition 8 was obtained.

[0253] <Example 9>

[0254] In Example 5, 2 parts by mass of curing accelerator a (“C11Z-A”, melting point 192 °C, curing accelerator having a triazine skeleton, manufactured by Shikoku Kasei) was changed to 2 parts by mass of curing accelerator b (“2E4MZ-A”, melting point 210 °C, curing accelerator having a triazine skeleton, manufactured by Shikoku Kasei). Except for the above matters, the operation was the same as in Example 5, and resin composition 9 was obtained.

[0255] <Example 10>

[0256] In Example 5, 2 parts by mass of curing accelerator a (“C11Z-A”, melting point 192 °C, curing accelerator having a triazine skeleton, manufactured by Shikoku Kasei) was changed to 2 parts by mass of curing accelerator c (“VT”, melting point 240 °C, curing accelerator having a triazine skeleton, manufactured by Shikoku Kasei). Except for the above matters, the operation was the same as in Example 5, and resin composition 10 was obtained.

[0257] <Example 11>

[0258] In Example 5, 2 parts by mass of curing accelerator a (“C11Z-A”, melting point 192 °C, curing accelerator having a triazine skeleton, manufactured by Shikoku Kasei) was changed to 2 parts by mass of curing accelerator d (“C11Z-CNS”, melting point 129 °C, curing accelerator having a triazine skeleton, manufactured by Shikoku Kasei). Except for the above matters, the operation was the same as in Example 5, and resin composition 11 was obtained.

[0259] <Comparative Example 1>

[0260] In Example 1,

[0261] The amount of liquid resin a (“ZX-1059”, a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) was changed from 5 parts by mass to 7 parts by mass.

[0262] The amount of solid resin a (“NC-3000-L”, biphenyl type aromatic epoxy resin, manufactured by Nippon Kayaku Co., Ltd.) was changed from 5 parts by mass to 1 part by mass;

[0263] Except for the above matters, the operation was carried out in the same manner as in Example 1 to obtain Resin Composition 12.

[0264] <Comparative Example 2>

[0265] In Example 1,

[0266] The amount of liquid resin a (“ZX-1059”, a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) was changed from 5 parts by mass to 3 parts by mass,

[0267] The amount of solid resin a (“NC-3000-L”, biphenyl type aromatic epoxy resin, manufactured by Nippon Kayaku Co., Ltd.) was changed from 3 parts by mass to 5 parts by mass;

[0268] Except for the above matters, the operation was carried out in the same manner as in Example 1 to obtain Resin Composition 13.

[0269] <Comparative Example 3>

[0270] In Example 1,

[0271] The amount of liquid resin a (“ZX-1059”, a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) was changed from 5 parts by mass to 8 parts by mass,

[0272] 3 parts by mass of solid resin a (“NC-3000-L”, biphenyl type aromatic epoxy resin, manufactured by Nippon Kayaku Co., Ltd.) was not used;

[0273] Except for the above matters, the operation was carried out in the same manner as in Example 1 to obtain Resin Composition 14.

[0274] <Comparative Example 4>

[0275] In Example 1, 2 parts by mass of curing accelerator a (“C11Z-A”, melting point 192 °C, curing accelerator having a triazine skeleton, manufactured by Shikoku Chemicals Corporation) was changed to 2 parts by mass of curing accelerator e (“2MZA-PW”, melting point 250 °C, curing accelerator having a triazine skeleton, manufactured by Shikoku Chemicals Corporation). Except for the above matters, the operation was carried out in the same manner as in Example 1 to obtain Resin Composition 15.

[0276] <Comparative Example 5>

[0277] In Example 1, 2 parts by mass of curing accelerator a (“C11Z-A”, melting point 192°C, a curing accelerator having a triazine skeleton, manufactured by Shikoku Kasei Co., Ltd.) was changed to 2 parts by mass of curing accelerator f (“1B2PZ”, melting point 40°C, a curing accelerator, manufactured by Shikoku Kasei Co., Ltd.). Except for the above matters, the operation was carried out in the same manner as in Example 1 to obtain Resin Composition 16.

[0278] <Evaluation of Storage Stability>

[0279] The temperature of each resin composition just after production was maintained at 25 ± 2°C, and the viscosity A was measured using an E-type viscometer (“RE-80U” manufactured by Toki Sangyo Co., Ltd., 3° × R9.7 conical rotor) under the condition of a rotation speed of 5 rpm.

[0280] Next, after standing at room temperature (25°C) for 3 days, the temperature of each resin composition after standing was maintained at 25 ± 2°C, and the viscosity B was measured using an E-type viscometer (“RE-80U” manufactured by Toki Sangyo Co., Ltd., 3° × R9.7 conical rotor) under the condition of a rotation speed of 5 rpm. The ratio of viscosity A / viscosity B was calculated and evaluated according to the following criteria:

[0281] ○: Viscosity A / viscosity B is 1.0 or more and 1.5 or less;

[0282] ×: Viscosity A / viscosity B exceeds 1.5.

[0283] <Measurement of Change Rate of Rough Surface after Defect Removal and Evaluation of Swelling after Reflow Soldering>

[0284] -Fabrication of Evaluation Substrate-

[0285] As a support, a glass cloth base epoxy resin double-sided copper-clad laminate having a copper foil on the surface (copper foil thickness 18 μm, substrate thickness 0.8 mm, “R1515A” manufactured by Panasonic Corporation) was prepared. All of the copper foil on the surface of the inner layer substrate was etched away. Then, it was dried at 190°C for 30 minutes. Each resin composition was uniformly coated on the above support using a doctor blade so that the thickness of the resin composition layer became 100 μm, to obtain a magnetic sheet. The obtained magnetic sheet was heated at 190°C for 90 minutes, whereby the resin composition layer was thermally cured to obtain a sheet-like cured product.

[0286] (Measurement of Ra of the resin composition after thermal curing (before defect removal treatment))

[0287] For the magnetic layer after heat curing of the sheet-shaped cured product, the Ra (average roughness of 10 points) was determined using a non-contact surface roughness meter (manufactured by Veeco Instruments, WYKONT3300).

[0288] It should be noted that Ra is the average value of the heights calculated within the entire measurement area. Specifically, it is the value obtained by measuring the absolute value of the height that varies within the measurement area from the surface serving as the average line and performing arithmetic averaging, and can be expressed by the following formula (1). Here, M and N in formula (1) represent the number of data in each direction of the array;

[0289] [Mathematical formula 1]

[0290]

[0291] (Defect removal treatment)

[0292] The sheet-shaped cured product was immersed in a swelling solution (manufactured by Atotech Japan Co., Ltd., Swelling Dip Securiganth P) at 60 °C for 5 minutes for swelling treatment. Next, it was immersed in an alkaline oxidizing agent solution (manufactured by Atotech Japan Co., Ltd., Concentrate Compact P (aqueous solution of KMnO4: 60 g / L, NaOH: 40 g / L)) at 80 °C for 5 minutes for roughening treatment of the magnetic layer surface. Finally, it was immersed in a neutralizing solution (manufactured by Atotech Japan Co., Ltd., Reduction Solution Securiganth P) at 40 °C for 5 minutes for neutralization treatment. Then, the inner layer circuit board was washed with water and dried to obtain an evaluation substrate.

[0293] (Measurement of Ra after defect removal treatment)

[0294] For the magnetic layer after defect removal treatment, the Ra (average roughness of 10 points) was determined using a non-contact surface roughness meter (manufactured by Veeco Instruments, WYKONT3300).

[0295] (Measurement of rough surface change rate)

[0296] The ratio of Ra before defect removal treatment to Ra after defect removal treatment (Ra before defect removal treatment / Ra after defect removal treatment) was calculated as the rough surface change rate.

[0297] (Evaluation of swelling after reflow soldering)

[0298] On the roughened magnetic layer surface of the evaluation substrate, an electroless copper plating process was performed using an electroless copper plating solution (manufactured by Atotech Japan Co., Ltd.). The thickness of the electroless copper plating layer was 1 μm. Then, electrolytic copper plating was performed on the electroless copper plating layer to form a conductor layer (copper layer) with a total thickness of 30 μm, obtaining a multilayer wiring substrate.

[0299] For the obtained multilayer wiring substrate, a reflow soldering process was performed using a reflow soldering device (manufactured by ANTOM, HAS-6116) under the condition of a heat history of 1 minute or more at 260 °C or higher. After observing the conductor layer after the reflow soldering process, the presence or absence of swelling was confirmed, and evaluation was performed according to the following criteria:

[0300] ○: No swelling

[0301] △: Swelling at the end face

[0302] ×: Swelling over the entire surface.

[0303] [Table 1]

[0304]

[0305] [Table 2]

[0306]

[0307] It can be seen that for Examples 1 to 11, the storage stability is excellent, and even after the reflow soldering treatment is performed after forming the conductor layer, no adverse conditions such as swelling occur. It can also be seen that for Examples 1 to 11, since the ratio of Ra before the contamination removal treatment to Ra after the contamination removal treatment (roughened surface change rate) is low, the contamination resistance is excellent. As a result, the adhesion between the magnetic layer and the plated conductor layer is excellent. In addition, for Examples 1 to 11, since the contamination resistance is excellent, the magnetic layer becomes very smooth even after the contamination removal treatment. Therefore, a plating seed layer (electroless plating layer) based on electroless plating can be formed on the surface of the very smooth magnetic layer. Therefore, it can also be seen that after forming a circuit by the semi-additive method, the unnecessary plating seed layer can be easily removed by etching.

[0308] Explanation of reference numerals

[0309] 10 Core substrate

[0310] 11 Support substrate

[0311] 12 First metal layer

[0312] 13 Second metal layer

[0313] 14 Through hole

[0314] 20 Plating layer

[0315] 30a resin composition

[0316] 30 magnetic layer

[0317] 40 conductor layer

[0318] 41 patterned conductor layer

[0319] 100 circuit board

[0320] 200 inner layer substrate

[0321] 200a first main surface

[0322] 200b second main surface

[0323] 220 via hole

[0324] 220a in-via wiring

[0325] 240 external terminal

[0326] 300 magnetic part

[0327] 310 magnetic sheet

[0328] 320a resin composition layer

[0329] 320 first insulating layer

[0330] 330 support

[0331] 340 second insulating layer

[0332] 360 through hole

[0333] 360a in-through hole wiring

[0334] 400 coil-shaped conductive structure

[0335] 420 first conductor layer

[0336] 420a pad

[0337] 440 second conductor layer.

Claims

1. A resin composition comprising: (A) Magnetic powder, (B-1) Solid resin, (B-2) Liquid resin, and (C) A curing accelerator having a melting point of 120 °C or higher and 245 °C or lower, (B-1) component contains solid epoxy resin, (B-2) component contains liquid epoxy resin, When the content of (B-1) component is set as b1 and the content of (B-2) component is set as b2, b1 / b2 is 0.15 or more and 0.45 or less, The content of the (B-1) component is the content when the non-volatile components in the resin composition are set to 100% by mass, and the content of the (B-2) component is the content when the non-volatile components in the resin composition are set to 100% by mass, When the content of the (C) component in the resin composition is set to 100% by mass and denoted as c1, b1 / c1 is 0.1 or more and 5 or less, and b2 / c1 is 1 or more and 20 or less, When the non-volatile components in the resin composition are set to 100% by mass, the content of the (A) component is 60% by mass or more and 98% by mass or less, When the non-volatile components in the resin composition are set to 100% by mass, the content of the (B-1) component is 0.5% by mass or more and 10% by mass or less, When the non-volatile components in the resin composition are set to 100% by mass, the content of the (B-2) component is 1% by mass or more and 25% by mass or less, When the non-volatile components in the resin composition are set to 100% by mass, the content of the (C) component is 0.1% by mass or more and 10% by mass or less.

2. The resin composition according to claim 1, wherein, When the content of the (B-1) component is set as b1 and the content of the (B-2) component is set as b2, b1 / b2 is 0.23 or more, The content of the (B-1) component is the content when the non-volatile components in the resin composition are set to 100% by mass, and the content of the (B-2) component is the content when the non-volatile components in the resin composition are set to 100% by mass.

3. The resin composition according to claim 1, wherein, When the content of the (B-1) component is set as b1 and the content of the (B-2) component is set as b2, b1 / b2 is 0.3 or less, The content of the (B-1) component is the content when the non-volatile components in the resin composition are set to 100% by mass, and the content of the (B-2) component is the content when the non-volatile components in the resin composition are set to 100% by mass.

4. The resin composition according to claim 1, wherein, (C) component has a triazine skeleton.

5. The resin composition according to claim 1, wherein (A) component is soft magnetic powder.

6. The resin composition according to claim 1, wherein, (A) component is iron oxide powder.

7. The resin composition according to claim 6, wherein, The iron oxide powder is a ferrite containing at least one element selected from Ni, Cu, Mn, and Zn.

8. The resin composition according to claim 1, wherein (A) component is at least one selected from Fe-Mn-based ferrite and Fe-Mn-Zn-based ferrite.

9. The resin composition according to claim 1, wherein, When the non-volatile components in the resin composition are set to 100% by mass, the content of the (A) component is 75% by mass or more.

10. The resin composition according to claim 1, wherein, When the non-volatile components in the resin composition are set to 100% by mass, the content of the (A) component is 90% by mass or less.

11. The resin composition according to claim 1, wherein, When the non-volatile components in the resin composition are set to 100% by mass, the content of the (B-1) component is 1.5% by mass or more.

12. The resin composition according to claim 1, wherein, When the nonvolatile components in the resin composition are set to 100% by mass, the content of the component (B-1) is 5% by mass or less.

13. The resin composition according to claim 1, wherein, When the nonvolatile components in the resin composition are set to 100% by mass, the content of the component (B-2) is 10% by mass or more.

14. The resin composition according to claim 1, wherein, When the nonvolatile components in the resin composition are set to 100% by mass, the content of the component (B-2) is 15% by mass or less.

15. The resin composition according to claim 1, wherein, When the nonvolatile components in the resin composition are set to 100% by mass, the content of the component (C) is 1% by mass or more.

16. The resin composition according to claim 1, wherein, When the nonvolatile components in the resin composition are set to 100% by mass, the content of the component (C) is 3% by mass or less.

17. The resin composition according to claim 1, which is used for forming an inductor element.

18. The resin composition according to claim 1, which is in a paste form.

19. The resin composition according to claim 1, which is used for filling a through-hole.

20. A magnetic sheet, comprising: a support, and a resin composition layer formed of the resin composition according to any one of claims 1 to 19 provided on the support.

21. A circuit board, comprising: a board having a through-hole, and a cured product of the resin composition according to any one of claims 1 to 19 filled in the through-hole.

22. A circuit board, comprising a magnetic layer which is a cured product of the resin composition according to any one of claims 1 to 19.

23. An inductor board, comprising the circuit board according to claim 21 or 22.

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