Method for manufacturing a wiring board

Abstract

To provide a manufacturing method of a wiring board capable of obtaining a wiring board with a small transmission loss in a high frequency band.SOLUTION: There is provided a manufacturing method of a wiring board 100 including a substrate 10, a conductor wiring 20 provided on the substrate 10, and an insulating magnetic layer 30 covering at least a part of the circumference of the conductor wiring 20 and made of an insulator containing a magnetic material, and the manufacturing method of a wiring board 100 includes a step (I) of forming an insulating material layer 2 on the substrate 10, a step (II) of forming an opening H1 opening on the opposite side of the substrate 10 on the insulating material layer 2, a step (III) of forming the insulating magnetic layer 30 at least on an inner side surface of the opening H1, and a step (IV) of forming the conductor wiring 20 on the insulating magnetic layer 30.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a wiring board. [Background technology]

[0002] Mobile communication devices such as mobile phones, their base station equipment, network-related electronic devices such as servers and routers, and large computers are required to transmit and process large volumes of information at high speeds with low loss. To meet these demands, the printed wiring boards mounted on such devices are increasingly handling higher frequencies of electrical signals. However, since electrical signals have the property of being more easily attenuated as their frequency increases, printed wiring boards that handle high-frequency electrical signals are required to have lower transmission loss than ever before.

[0003] In response to the above demands, known measures include reducing the surface roughness of conductor layers including wiring to suppress transmission loss caused by high surface roughness of the conductor layers (see, for example, Patent Document 1 below), and using polyphenylene ether-containing resins with small dielectric constants and dielectric tangents as substrate materials to reduce transmission loss caused by dielectrics (see, for example, Patent Document 2 below). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-016006 [Patent Document 2] International Publication No. 2014 / 034103 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] However, as the frequency of electrical signals increases in post-5G / 6G, it will become difficult to address the decrease in transmission loss using only the measures mentioned above.

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a method for manufacturing a wiring board, which can provide a wiring board with small transmission loss in the high frequency band. [Means for solving the problem]

[0007] One aspect of the present invention provides a method for manufacturing a wiring board comprising a substrate, conductor wiring provided on the substrate, and an insulating magnetic layer covering at least a portion of the periphery of the conductor wiring and made of an insulator containing a magnetic material, the method comprising the steps of: (I) forming an insulating material layer on the substrate; (II) forming an opening in the insulating material layer that opens to the side opposite the substrate; (III) forming an insulating magnetic layer on at least the inner side of the opening; and (IV) forming the conductor wiring on the insulating magnetic layer.

[0008] According to the method for manufacturing a wiring board according to the above aspect, it is possible to obtain a wiring board having small transmission loss in the high frequency band. The reason for this effect is believed to be that magnetic flux generated at high frequency passes through an insulator containing a magnetic material, thereby reducing eddy currents inside the conductor wiring, thereby reducing the skin effect.

[0009] In one aspect, the step (III) may be a step of forming an insulating magnetic layer on the inner side of the opening and on the surface of the insulating material layer other than the opening, and the step (IV) may include a step of producing a laminate in which a conductor layer is formed on the insulating magnetic layer, and a step of forming conductor wiring by removing a portion of the laminate opposite the substrate.

[0010] In the above case, a conductor wiring can be formed within the opening, the conductor wiring having a bottom surface located on the substrate side, a top surface located on the opposite side to the substrate, and a pair of side surfaces located between the bottom surface and the top surface, and a wiring board can be obtained in which an insulating magnetic layer covers at least the bottom surface and the pair of side surfaces of the conductor wiring.

[0011] In one aspect, from the viewpoint of ease of signal propagation, the coating thickness of the insulating magnetic layer may be 0.1 to 100 μm.

[0012] In one aspect, from the viewpoint of insulating properties, the magnetic material may be a metal oxide or an amorphous metal.

[0013] In one aspect, the insulator may have a relative magnetic permeability of 2 to 1,000 from the viewpoint of suppressing transmission loss.

[0014] In one aspect, the insulator may have a relative dielectric constant of 1-30 from the viewpoint of suppressing transmission loss. Effect of the Invention

[0015] According to the present invention, it is possible to provide a method for manufacturing a wiring board that can provide a wiring board with small transmission loss in the high frequency band. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a first embodiment of a method for manufacturing a wiring board. [Diagram 2] FIG. 2 is a schematic cross-sectional view showing the first embodiment of the method for manufacturing a wiring board, subsequent to FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing a second embodiment of the method for manufacturing a wiring board. [Figure 4] FIG. 4 is a schematic cross-sectional view showing a second embodiment of the method for manufacturing a wiring board, following FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are given the same reference numerals, and duplicated descriptions will be omitted. Furthermore, unless otherwise specified, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to the illustrated ratios.

[0018] The term "layer" includes a structure having a shape formed on the entire surface as well as a structure having a shape formed on a part of the surface when observed in a plan view. In addition, the materials exemplified below may be used alone or in combination of two or more types unless otherwise specified. When a plurality of substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless otherwise specified. A numerical range indicated using "~" indicates a range including the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this specification, the upper limit or lower limit of a numerical range of a certain stage may be replaced by the upper limit or lower limit of a numerical range of another stage. In the numerical ranges described in this specification, the upper limit or lower limit of the numerical range may be replaced by the values ​​shown in the examples.

[0019] <Insulating Magnetic Layer Forming Composition> The insulating magnetic layer-forming composition is a curable composition that contains a magnetic material, and can be formed, for example, by mixing a binder resin varnish and a magnetic powder.

[0020] The magnetic material may be, for example, at least one type of magnetic powder selected from the group consisting of a simple metal, an alloy, and a metal compound. The alloy may include at least one type selected from the group consisting of a solid solution, a eutectic, an amorphous metal, and an intermetallic compound. The metal compound may be a metal oxide.

[0021] From the viewpoint of insulation, the magnetic material may be a metal oxide or an amorphous metal, or may be a metallic glass magnetic powder. Examples of the metal oxide include ferrite. Examples of the amorphous metal include Fe-based nanocrystalline alloys and Co-based nanocrystalline alloys.

[0022] The magnetic powder may contain one type of metal element or multiple types of metal elements. The metal element contained in the magnetic powder may be, for example, a base metal element, a precious metal element, a transition metal element, or a rare earth element. The metal element contained in the magnetic powder may be, for example, at least one selected from the group consisting of iron (Fe), copper (Cu), titanium (Ti), manganese (Mn), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), tin (Sn), chromium (Cr), barium (Ba), strontium (Sr), lead (Pb), silver (Ag), praseodymium (Pr), neodymium (Nd), samarium (Sm), and dysprosium (Dy). The magnetic powder may contain elements other than metal elements. The magnetic powder may contain, for example, oxygen, boron, or silicon.

[0023] The magnetic powder may be at least one composition selected from the group consisting of Fe-Si alloys, Fe-Si-Al alloys (Sendust), Fe-Ni alloys (Permalloy), Fe-Cu-Ni alloys (Permalloy), Fe-Cr-Si alloys, Fe-Cr alloys, Fe-Ni-Cr alloys (electromagnetic stainless steel), Nd-Fe-B alloys (rare earth magnets), Al-Ni-Co alloys (Alnico magnets) and ferrites. The ferrites may be, for example, spinel ferrites, hexagonal ferrites, or garnet ferrites.

[0024] The Fe-based alloy may be an Fe amorphous alloy. The Fe amorphous alloy powder is an amorphous powder obtained by quenching an alloy in which the main component Fe is melted at high temperature together with other elements such as Si, and is also known as metallic glass. The Fe amorphous alloy powder can be produced according to a method well known in the art. The Fe amorphous alloy powder may be commercially available products such as those manufactured by Epson Atmix Corporation under the product names "AW2-08" and "KUAMET-6B2", those manufactured by Daido Steel Co., Ltd. under the product names "DAPMS3", "DAPMS7", "DAPMSA10", "DAPPB", "DAPPC", "DAPMKV49", "DAP410L", "DAP430L", and "DAPHYB series", and those manufactured by Kobe Steel, Ltd. under the product names "MH45D", "MH28D", "MH25D", and "MH20D".

[0025] The magnetic powder may contain one of the above elements and compositions, or may contain a plurality of the above elements and compositions.

[0026] The magnetic powder may be spherical, approximately spherical, flake-like, or elliptical. The magnetic powder may also be in various other shapes, some of which may have corners. From the viewpoint of excellent flowability, the magnetic powder may be spherical.

[0027] The average particle size of the magnetic powder may be 0.005 to 50 μm. The "average particle size" described in this specification means the particle size at an integrated value of 50% (volume basis) in the particle size distribution. The magnetic powder may be a mixture of particles having two or three different average particle sizes so as to be closely packed.

[0028] The magnetic powder may have a coating on the surface. The coating may be formed of, for example, an inorganic salt, an acrylic resin, a silicon acid compound, or the like. The magnetic powder may also be entirely or partially coated with a surface treatment agent. The surface treatment agent may be, for example, an inorganic oxide, a phosphoric acid compound, a phosphate compound, an inorganic surface treatment agent such as a silane coupling agent, an organic surface treatment agent such as montan wax, or a resin cured product. The coupling agent described below may also be used as the surface treatment agent. For example, the surface of a metal-based magnetic powder such as an Fe-based alloy may be entirely or partially coated with an insulating material. Examples of insulating materials include silica, titania, calcium phosphate, montan wax, and epoxy resin cured products.

[0029] The magnetic powder may include magnetic powder whose surface is coated with an insulating material (hereinafter referred to as insulating coated magnetic powder). The insulating coated magnetic powder may be used alone or in combination of two or more. The average particle diameters of two or more insulating coated magnetic powders may be the same or different. In addition, the insulating coated magnetic powder may be used in combination with a magnetic powder having no insulating coating (hereinafter referred to as uncoated magnetic powder). The average particle diameter of the uncoated magnetic powder may be the same as or different from the average particle diameter of the insulating coated magnetic powder. For example, from the viewpoint of exhibiting insulating properties, the average particle diameter of the uncoated magnetic powder may be smaller than the average particle diameter of the insulating coated magnetic powder.

[0030] The insulating coated magnetic powder may be Fe amorphous alloy powder having an insulating coating. For example, commercially available products such as "KUAMET9A4" (Fe-Si-B alloy, D50: 20 μm, with insulating coating) manufactured by Epson Atmix Corporation and "SAP-2D(C)" (Fe-Si-B-PNb-Cr alloy, D50: 2.3 μm, with insulating coating) manufactured by Shinto Kogyo Co., Ltd. can be used as the insulating coated magnetic powder. For example, commercially available products such as "SAP-2D" (Fe-Si-B-PNb-Cr alloy, D50: 2.3 μm, without insulating coating) manufactured by Shinto Kogyo Co., Ltd. and soft ferrite powder "BSN-125" (Ni-Zn alloy, D50: 10 μm, without insulating coating) manufactured by Toda Kogyo Co., Ltd. can be used as the uncoated magnetic powder.

[0031] The content of the magnetic powder in the insulating magnetic layer-forming composition may be 70 to 99 parts by mass, or 80 to 90 parts by mass, when the total mass of the composition is 100 parts by mass.

[0032] The binder resin varnish may be a resin composition.

[0033] The resin composition may contain an epoxy resin.

[0034] Examples of epoxy resins include epoxy resins having a condensed ring structure such as naphthalene type epoxy resins, naphthalene type tetrafunctional epoxy resins, naphthol type epoxy resins, naphthylene ether type epoxy resins, anthracene type epoxy resins, dicyclopentadiene type epoxy resins, naphthalene type epoxy resins, naphthalene type tetrafunctional epoxy resins, naphthol type epoxy resins, naphthylene ether type epoxy resins, and dicyclopentadiene type epoxy resins; bisphenol A type epoxy resins; bisphenol F type epoxy resins; bisphenol S type epoxy resins; bisphenol AF type epoxy resins; and trisphenol type epoxy resins. Resins; novolac type epoxy resins; naphthol novolac type epoxy resins; phenol novolac type epoxy resins; tert-butyl-catechol type epoxy resins; 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; spiro ring-containing epoxy resins; cyclohexane dimethanol type epoxy resins; trimethylol type epoxy resins; tetraphenylethane type epoxy resins; bixylenol type epoxy resins, etc. These may be used alone or in combination of two or more.

[0035] The epoxy resin may be an epoxy resin having two or more epoxy groups in one molecule, and may be in a liquid or solid state at a temperature of 25°C.

[0036] Examples of epoxy resins that are liquid at 25°C (hereinafter also referred to as "liquid epoxy resins") that can be used include 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, cyclohexane dimethanol type epoxy resins, glycidyl amine type epoxy resins, and epoxy resins having a butadiene structure. Liquid epoxy resins include "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resins) manufactured by DIC, "828US", "jER828EL" (bisphenol A type epoxy resin), "jER807" (bisphenol F type epoxy resin), "jER152" (phenol novolac type epoxy resin), "630", and "630LSD" (glycidylamine type epoxy resin) manufactured by Mitsubishi Chemical, and "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel & Sumitomo Metal Chemical. Commercially available products that can be used include "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation, "Celloxide 2021P" (alicyclic epoxy resin having an ester skeleton) and "PB-3600" (epoxy resin having a butadiene structure) manufactured by Daicel Corporation, "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., "630LSD" (glycidylamine type epoxy resin) manufactured by Mitsubishi Chemical Corporation, and "EP-3980S" (glycidylamine type epoxy resin) manufactured by ADEKA Corporation.

[0037] Examples of epoxy resins that are solid at 25°C include naphthalene-type tetrafunctional epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, and tetraphenylethane-type epoxy resins. The solid epoxy resins are "HP4032H" (naphthalene type epoxy resin), "HP-4700", "HP-4710" (naphthalene type tetrafunctional epoxy resin), "N-690" (cresol novolac type epoxy resin), "N-695", "N-680" (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" (naphthylene ether type epoxy resin) manufactured by DIC Corporation, and "EPPN-502H" (trisphenol type epoxy resin), "NC7000L" (naphthol novolac type epoxy resin), "NC3000H", "NC3000", "NC3000L", "NC" manufactured by Nippon Kayaku Co., Ltd. Commercially available products such as "3100" (biphenyl type epoxy resin), "ESN475V" (naphthalene type epoxy resin), "ESN485" (naphthol novolac type epoxy resin) manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., "YX4000H", "YL6121" (biphenyl type epoxy resin), "YX4000HK" (bixylenol type epoxy resin), "YX8800" (anthracene type epoxy resin) manufactured by Mitsubishi Chemical Corporation, "PG-100" and "CG-500" manufactured by Osaka Gas Chemical Co., Ltd., "YL7760" (bisphenol AF type epoxy resin), "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Corporation, "jER1010" (solid bisphenol A type epoxy resin), "jER1031S" (tetraphenylethane type epoxy resin), and "157S70" (novolac type epoxy resin) manufactured by Mitsubishi Chemical Corporation can be used.

[0038] The resin composition may contain a curing agent. Examples of the curing agent include phenol-based curing agents, naphthol-based curing agents, benzoxazine-based curing agents, and cyanate ester-based curing agents. The curing agent may be used alone or in combination of two or more.

[0039] As the phenol-based hardener and naphthol-based hardener, a phenol-based hardener having a novolac structure, a naphthol-based hardener having a novolac structure, a nitrogen-containing phenol-based hardener, and a triazine skeleton-containing phenol-based hardener can be used.

[0040] As the phenol-based curing agent and naphthol-based curing agent, commercially available products such as "MEH-7700", "MEH-7810", and "MEH-7851" manufactured by Meiwa Kasei Co., Ltd., "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd., "SN170", "SN180", "SN190", "SN475", "SN485", "SN495V", "SN375", and "SN395" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., "TD2090", "TD2090-60M", "LA-7052", "LA-7054", "LA-1356", "LA-3018", "LA-3018-50P", "EXB-9500", "HPC-9500", "KA-1160", "KA-1163", and "KA-1165" manufactured by Gun-ei Chemical Co., Ltd., and "GDP-6115L", "GDP-6115H", and "ELPC75" can be used.

[0041] As the benzoxazine-based curing agent, commercially available products such as "HFB2006M" manufactured by Showa Polymer Co., Ltd., "Pd" and "Fa" manufactured by Shikoku Chemical Industry Co., Ltd. can be used.

[0042] Examples of the cyanate ester curing agent include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanate phenyl-1-(methylethylidene))benzene, bis(4-cyanate phenyl)thioether, and bis(4-cyanate phenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins are partially converted to triazine.

[0043] As the cyanate ester curing agent, commercially available products such as "PT30" and "PT60" (both of which are phenol novolac type multifunctional cyanate ester resins), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been converted to triazine and formed into a trimer) manufactured by Lonza Japan Co., Ltd. can be used.

[0044] The content of the curing agent in the resin composition may be 0.1 parts by mass or more, 0.3 parts by mass or more, or 0.5 parts by mass or more, and may be 5 parts by mass or less, 3 parts by mass or less, or 2 parts by mass or less, based on 100 parts by mass of the resin component in the resin composition.

[0045] The resin composition may contain a curing accelerator. Examples of the curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators, and examples of the curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, and metal-based curing accelerators. The curing accelerators may be used alone or in combination of two or more.

[0046] Examples of phosphorus-based curing accelerators include triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, and butyltriphenylphosphonium thiocyanate.

[0047] Examples of the amine-based curing accelerator include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene, and examples of such accelerators include 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene.

[0048] Examples of the imidazole-based curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, and 1-benzyl-2-methylimidazole. Phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl -(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct imidazole compounds such as 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, and 2-phenylimidazoline, as well as adducts of imidazole compounds and epoxy resins.

[0049] As the imidazole-based curing accelerator, commercially available products such as "P200-H50" manufactured by Mitsubishi Chemical Corporation can be used.

[0050] Examples of the guanidine curing accelerator include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide.

[0051] Examples of metal-based curing accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Examples of organometallic complexes include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate, organocopper complexes such as copper(II) acetylacetonate, organozinc complexes such as zinc(II) acetylacetonate, organoiron complexes such as iron(III) acetylacetonate, organonickel complexes such as nickel(II) acetylacetonate, and organomanganese complexes such as manganese(II) acetylacetonate. Examples of organometallic salts include zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

[0052] The content of the curing accelerator in the resin composition may be 0.001 parts by mass or more, 0.005 parts by mass or more, or 0.01 parts by mass or more, and may be 0.1 parts by mass or less, 0.08 parts by mass or less, or 0.05 parts by mass or less, relative to 100 parts by mass of the non-volatile components in the resin composition.

[0053] The resin composition may contain a thermoplastic resin. Examples of the thermoplastic resin include phenoxy resin, polyvinyl acetal resin, polyolefin resin, polybutadiene resin, siloxane resin, poly(meth)acrylic resin, polyalkylene resin, polyalkyleneoxy resin, polyisoprene resin, polyisobutylene resin, polyimide resin, polyamideimide resin, polyetherimide resin, polysulfone resin, polyethersulfone resin, polyphenylene ether resin, polycarbonate resin, polyetheretherketone resin, and polyester resin.

[0054] Examples of the phenoxy resin include "1256" and "4250" (both of which are phenoxy resins containing a bisphenol A structure), "YX8100" (phenoxy resin containing a bisphenol S skeleton), and "YX6954" (phenoxy resin containing a bisphenol acetophenone structure) manufactured by Mitsubishi Chemical Corporation. In addition, commercially available products such as "FX280" and "FX293" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., and "YX7180", "YX6954", "YX7553", "YX7553BH30", "YL7553BH30", "YL7769", "YL6794", "YL7213", "YL7290", "YL7891", and "YL7482" manufactured by Mitsubishi Chemical Corporation can also be used.

[0055] The thermoplastic resin may have one or more structures selected from a polybutadiene structure, a polysiloxane structure, a poly(meth)acrylate structure, a polyalkylene structure, a polyalkyleneoxy structure, a polyisoprene structure, a polyisobutylene structure, and a polycarbonate structure in the molecule. These structures may be included in the main chain or in the side chain. The polybutadiene structure may be partially or entirely hydrogenated. The polyalkyleneoxy structure may be a polyalkyleneoxy structure having 2 to 15 carbon atoms, a polyalkyleneoxy structure having 3 to 10 carbon atoms, or a polyalkyleneoxy structure having 5 to 6 carbon atoms.

[0056] The thermoplastic resin may have a number average molecular weight (Mn) of 1,000 or more, 1,500 or more, 3,000 or more, or 5,000 or more, and may be 1,000,000 or less, or 900,000 or less. The number average molecular weight (Mn) refers to the number average molecular weight in terms of polystyrene measured using GPC (gel permeation chromatography).

[0057] The thermoplastic resin may have a functional group capable of reacting with an epoxy resin. The functional group capable of reacting with an epoxy resin may be one or more functional groups selected from the group consisting of a hydroxy group, a carboxy group, an acid anhydride group, a phenolic hydroxyl group, an epoxy group, an isocyanate group, and a urethane group.

[0058] The polybutadiene resin may be commercially available products such as "Ricon 130MA8", "Ricon 130MA13", "Ricon 130MA20", "Ricon 131MA5", "Ricon 131MA10", "Ricon 131MA17", "Ricon 131MA20", and "Ricon 184MA6" (polybutadiene containing an acid anhydride group) manufactured by Cray Valley Corporation, "GQ-1000" (polybutadiene having hydroxyl groups and carboxyl groups introduced therein), "G-1000", "G-2000", and "G-3000" (polybutadiene having hydroxyl groups at both ends), "GI-1000", "GI-2000", and "GI-3000" (polybutadiene having hydrogenated hydroxyl groups at both ends) manufactured by Nippon Soda Co., Ltd., and "FCA-061L" (hydrogenated polybutadiene skeleton epoxy resin) manufactured by Nagase ChemteX Corporation.

[0059] As the poly(meth)acrylic resin, commercially available products such as Teisan Resin manufactured by Nagase ChemteX Corporation, and ME-2000, W-116.3, W-197C, KG-25, and KG-3000 manufactured by Negami Chemical Industries, Ltd. can be used.

[0060] As the polycarbonate resin, commercially available products such as "T6002" and "T6001" (polycarbonate diols) manufactured by Asahi Kasei Chemicals Corporation, and "C-1090", "C-2090", and "C-3090" (polycarbonate diols) manufactured by Kuraray Co., Ltd. can be used.

[0061] The thermoplastic resins used were Shin-Etsu Silicone's "SMP-2006", "SMP-2003PGMEA", and "SMP-5005PGMEA", linear polyimides made from amine-terminated polysiloxanes and tetrabasic acid anhydrides (see, for example, International Publication No. 2010 / 053185, JP 2002-12667 A and JP 2000-319386 A), Asahi Kasei Fibers' "PTXG-1000" and "PTXG-1800", Kuraray's "KL-610" and "KL613", Kaneka's "SIBSTAR-073T" (styrene-isobutylene-styrene triblock copolymer) and "SIBSTAR-042D" (styrene-isobutylene diblock copolymer), and Denki Kagaku Kogyo's "Denka Butyral". Commercially available products such as "4000-2", "Denka Butyral 5000-A", "Denka Butyral 6000-C", "Denka Butyral 6000-EP", Sekisui Chemical Co., Ltd.'s S-LEC BH series, BX series (e.g. BX-5Z), KS series (e.g. KS-1), BL series, BM series, New Japan Chemical Co., Ltd.'s "Rikacoat SN20" and "Rikacoat PN20", Toyobo Co., Ltd.'s "Vilomax HR11NN" and "Vilomax HR16NN", Hitachi Chemical Co., Ltd.'s "KS9100" and "KS9300", Sumitomo Chemical Co., Ltd.'s "PES5003P", Solvay Advanced Polymers' polysulfone "P1700" and "P3500", and Ganz Chemical Co., Ltd.'s "AC3832" may also be used.

[0062] The content of the thermoplastic resin in the resin composition may be 0.1 parts by mass or more, 0.3 parts by mass or more, or 0.5 parts by mass or more, and may be 20 parts by mass or less, 10 parts by mass or less, 5 parts by mass or less, or 3 parts by mass or less, based on 100 parts by mass of non-volatile components in the resin composition.

[0063] The resin composition may contain an active ester compound having one or more active ester groups in one molecule. The active ester compound may be used alone or in combination of two or more.

[0064] As the active ester compound, a compound having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, esters of heterocyclic hydroxy compounds, etc. Examples of such active ester compounds include those obtained by a condensation reaction between a carboxylic acid compound and / or a thiocarboxylic acid compound and a hydroxy compound and / or a thiol compound.

[0065] From the viewpoint of improving heat resistance, the active ester compound may be an active ester compound obtained from a carboxylic acid compound and a hydroxy compound, or may be an active ester compound obtained from a carboxylic acid compound and a phenol compound and / or a naphthol compound. Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, phenolphthaline, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolac, etc. Here, the term "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

[0066] Specific examples of the active ester compound include an active ester compound containing a dicyclopentadiene-type diphenol structure, an active ester compound containing a naphthalene structure, an active ester compound containing an acetylated product of phenol novolac, and an active ester compound containing a benzoylated product of phenol novolac. The term "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

[0067] As active ester compounds containing a dicyclopentadiene-type diphenol structure, "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T", "HPC-8000H-65TM", "EXB-8000L-65TM", and "EXB-8150-65T" (manufactured by DIC Corporation), as an active ester compound containing a naphthalene structure, "EXB9416-70BK" (manufactured by DIC Corporation), as an active ester compound containing an acetylated product of phenol novolac, "DC808" (manufactured by DIC Corporation), (manufactured by Mitsubishi Chemical Corporation), as an active ester compound containing a benzoyl compound of phenol novolac, "YLH1026" (manufactured by Mitsubishi Chemical Corporation), as an active ester compound which is an acetylated product of phenol novolac, "DC808" (manufactured by Mitsubishi Chemical Corporation), and as an active ester-based curing agent which is a benzoyl compound of phenol novolac, commercially available products such as "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), and "YLH1048" (manufactured by Mitsubishi Chemical Corporation) may be used.

[0068] When the resin composition contains an active ester compound and an epoxy resin, the ratio of the epoxy resin to the active ester compound, expressed as the ratio of [total number of epoxy groups in the epoxy resin]:[total number of active ester groups in the active ester compound], may be 1:0.01 to 1:5, 1:0.05 to 1:3, or 1:0.1 to 1:1.5.

[0069] The content of the active ester compound in the resin composition may be 1 part by mass or more, 1.5 parts by mass or more, or 2 parts by mass or more, and may be 40 parts by mass or less, 30 parts by mass or less, 20 parts by mass or less, 10 parts by mass or less, 8 parts by mass or less, or 5 parts by mass or less, relative to 100 parts by mass of the non-volatile components in the resin composition.

[0070] The resin composition may contain a carbodiimide compound having one or more carbodiimide groups (-N=C=N-) in one molecule. As the carbodiimide compound, a compound having two or more carbodiimide groups in one molecule may be used. The carbodiimide compound may be used alone or in combination of two or more.

[0071] The carbodiimide compound includes a compound having a structure represented by the following formula (A). -(X) p -N=C=N- …(A) [In the formula, X represents an alkylene group, a cycloalkylene group, or an arylene group, which may have a substituent. p represents an integer of 1 to 5. When there are a plurality of X's, they may be the same or different.]

[0072] The number of carbon atoms of the alkylene group represented by X (not including the number of carbon atoms of the substituent) may be 1 to 20, 1 to 10, 1 to 6, 1 to 4, or 1 to 3. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, and a butylene group.

[0073] The number of carbon atoms of the cycloalkylene group represented by X (not including the number of carbon atoms of the substituent) may be 3 to 20, 3 to 12, or 3 to 6. Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, and a cyclohexylene group.

[0074] The arylene group represented by X is a group in which two hydrogen atoms on an aromatic ring are removed from an aromatic hydrocarbon. The number of carbon atoms in the arylene group (not including the number of carbon atoms in the substituent) may be 6 to 24, 6 to 18, 6 to 14, or 6 to 10. Examples of the arylene group include a phenylene group, a naphthylene group, and an anthracenylene group.

[0075] The alkylene group, cycloalkylene group or aryl group represented by X may have a substituent. Examples of the substituent include a halogen atom, an alkyl group, an alkoxy group, a cycloalkyl group, a cycloalkyloxy group, an aryl group, an aryloxy group, an acyl group and an acyloxy group. Examples of the halogen atom used as a substituent include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom. The alkyl group and the alkoxy group as a substituent may be linear or branched, and may have 1 to 20, 1 to 10, 1 to 6, 1 to 4 or 1 to 3 carbon atoms. The cycloalkyl group and the cycloalkyloxy group as a substituent may have 3 to 20, 3 to 12 or 3 to 6 carbon atoms. The aryl group as a substituent is a group obtained by removing one hydrogen atom on the aromatic ring from an aromatic hydrocarbon, and may have 6 to 24, 6 to 18, 6 to 14 or 6 to 10 carbon atoms. The aryloxy group as a substituent may have 6 to 24, 6 to 18, 6 to 14 or 6 to 10 carbon atoms. The acyl group as a substituent has the formula: -C(=O)-R 1 (wherein R 1 represents an alkyl group or an aryl group. 1 The alkyl group represented by the formula (I) may be either linear or branched, and may have 1 to 20, 1 to 10, 1 to 6, 1 to 4, or 1 to 3 carbon atoms. 1 The number of carbon atoms of the aryl group represented by the formula: may be 6 to 24, 6 to 18, 6 to 14, or 6 to 10. The acyloxy group as a substituent is represented by the formula: -OC(=O)-R 2 (wherein R 2 represents an alkyl group or an aryl group.

[0076] In formula (A), p represents an integer of 1 to 5. p may be 1 to 4, 2 to 4, 2 or 3.

[0077] The content of the structure represented by formula (A) in the carbodiimide compound may be 50 parts by mass or more, 60 parts by mass or more, 70 parts by mass or more, 80 parts by mass or more, or 90 parts by mass or more, when the mass of the entire molecule of the carbodiimide compound is 100 parts by mass. The carbodiimide compound may be substantially composed of the structure represented by formula (A) except for the terminal structure. Examples of the terminal structure of the carbodiimide compound include an alkyl group, a cycloalkyl group, and an aryl group, which may have a substituent. The alkyl group, cycloalkyl group, and aryl group used as the terminal structure may be the same as the alkyl group, cycloalkyl group, and aryl group described for the substituent that the group represented by X may have. In addition, the substituent that the group used as the terminal structure may have may be the same as the substituent that the group represented by X may have.

[0078] The weight average molecular weight of the carbodiimide compound may be 500 or more, 600 or more, 700 or more, 800 or more, 900 or more, or 1000 or more, and may be 5000 or less, 4500 or less, 4000 or less, 3500 or less, or 3000 or less. The weight average molecular weight of the carbodiimide compound can be measured, for example, by gel permeation chromatography (GPC) method (polystyrene equivalent).

[0079] When the carbodiimide compound contains an isocyanate group (-N=C=O) in the molecule, the content of the isocyanate group in the carbodiimide compound (also referred to as the "NCO content") may be 5 mass% or less, 4 mass% or less, 3 mass% or less, 2 mass% or less, 1 mass% or less, or 0.5 mass% or less.

[0080] As the carbodiimide compound, commercially available products such as Carbodilite (registered trademark) V-02B, V-03, V-04K, V-07, and V-09 manufactured by Nisshinbo Chemical Inc., and Stavaxol (registered trademark) P, P400, and Hi-Kasil 510 manufactured by Rhein Chemie may be used.

[0081] The content of the carbodiimide compound in the resin composition may be 0.1 parts by mass or more, 0.3 parts by mass or more, or 0.5 parts by mass or more, and may be 3 parts by mass or less, 2 parts by mass or less, or 1.5 parts by mass or less, based on 100 parts by mass of the non-volatile components in the resin composition.

[0082] The resin composition may further contain other additives as necessary, such as flame retardants, organometallic compounds such as organocopper compounds, organozinc compounds, and organocobalt compounds, binders, thickeners, defoamers, leveling agents, adhesion promoters, and colorants.

[0083] The insulating magnetic layer forming composition may be in a paste form (hereinafter, referred to as "paste"). The paste may contain magnetic powder, an epoxy group-containing compound, and a curing agent.

[0084] The magnetic powder may be any of the magnetic powders described above.

[0085] The average particle size of the magnetic powder contained in the paste may be 0.05 to 200 μm, 0.5 to 100 μm, or 1 to 50 μm. If the magnetic powder is coated, the average particle size of the magnetic powder including the coating film may be within the above range.

[0086] The content of the magnetic powder in the paste may be 70% by mass or more, or 80% by mass or more, and 99% by mass or less, or 90% by mass or less, based on the total mass of the paste. The content of the magnetic powder in the paste may be 70 to 99% by mass, or 80 to 90% by mass, based on the total mass of the paste.

[0087] The epoxy group-containing compound means a compound having one or more epoxy groups in the molecule, and may be in the form of any of a monomer, an oligomer, and a polymer having a structural unit formed by polymerization of the monomer. The epoxy group-containing compound can be cured by heat treatment and function as a binder resin that binds the metal element-containing powder. An example of the epoxy group-containing compound is an oligomer and a polymer having two or more epoxy groups in the molecule, which are generally known as epoxy resins. Another example of the epoxy group-containing compound is a compound having one or more epoxy groups in the molecule but not containing a structural unit formed by polymerization (hereinafter referred to as an epoxy compound). Such an epoxy compound is generally known as a reactive diluent. The epoxy group-containing compound preferably includes at least one selected from the group consisting of epoxy resins and epoxy compounds.

[0088] The epoxy resin may be the same as that blended in the resin composition described above. good.

[0089] The molecular weight of the epoxy compound may be 100 or more, 150 or more, or 200 or more. When an epoxy compound having a molecular weight of 100 or more is used, volatilization before reaction with a curing agent can be suppressed by setting appropriate curing conditions. In addition, a low molecular weight can reduce the occurrence of defects in which the distance between crosslinking points after reaction is short and the cured product is prone to cracking. On the other hand, the molecular weight of the epoxy compound may be 700 or less, 500 or less, or 300 or less. When an epoxy compound having a molecular weight of 700 or less is used, a suitable viscosity can be easily obtained as a diluent.

[0090] The molecular weight of the epoxy compound may be 100 to 700, 150 to 500, or 200 to 300. When an epoxy compound having a molecular weight in such a range is used, it becomes easy to adjust the viscosity of the paste. Unlike components such as organic solvents that volatilize when heated, epoxy compounds are cured when heated and are incorporated into the cured product. Therefore, when an epoxy compound is used, it contributes to adjusting the viscosity of the paste and, at the same time, it is possible to suppress the deterioration of the properties of the cured product.

[0091] The epoxy compound may contain one or more epoxy groups in the molecule. The epoxy compound may be, for example, at least one selected from the group consisting of n-butyl glycidyl ether, versatic acid glycidyl ether, styrene oxide, ethylhexyl glycidyl ether, phenyl glycidyl ether, butylphenyl glycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, diethylene glycol diglycidyl ether, and trimethylolpropane triglycidyl ether. The epoxy compound may contain 500 ppm or less of ionic impurities such as free Na ions and free Cl ions.

[0092] The epoxy equivalent of the epoxy group-containing compound may be 80 g / eq to 350 g / eq, 100 g / eq to 300 g / eq, or 120 g / eq to 250 g / eq. When the epoxy equivalent is within the above range, the viscosity of the epoxy group-containing compound itself is low, making it easy to adjust the viscosity of the paste.

[0093] The epoxy group-containing compound preferably includes an epoxy group-containing compound that is liquid at 25° C. In this specification, "liquid at 25° C." means that the viscosity of the epoxy group-containing compound at 25° C. is 200 Pa·s or less. The above viscosity is a value measured using an E-type viscometer under the following conditions: temperature: 25° C., cone plate type: SPP, cone angle: 1°34', and rotation speed: 2.5 rpm. As the E-type viscometer, for example, a TV-33 type viscometer manufactured by Toki Sangyo Co., Ltd. can be used.

[0094] When an epoxy group-containing compound that is liquid at 25°C is used, the amount of volatile components such as organic solvents that are usually used to obtain fluidity can be significantly reduced. In one embodiment, a paste that does not contain organic solvents can be formed. In addition, the content of magnetic powder can be easily increased while ensuring appropriate fluidity as a paste. From these perspectives, the viscosity of the epoxy group-containing compound may be 100 Pa·s or less, 50 Pa·s or less, or 10 Pa·s or less.

[0095] The viscosity of the epoxy compound among the epoxy group-containing compounds may be lower than that of the liquid epoxy resin in terms of adjusting the paste viscosity. The viscosity of the epoxy compound may be 1 Pa s or less, 0.5 Pa s or less, or 0.1 Pa s or less.

[0096] The epoxy group-containing compound that is liquid at 25° C. may include at least one selected from the group consisting of an epoxy resin that is liquid at 25° C. and an epoxy compound that is liquid at 25° C. The content of the epoxy resin that is liquid at 25° C. may be 50 mass % or more, 70 mass % or more, 90 mass % or more, or 100 mass % based on the total mass of the epoxy group-containing compound.

[0097] The epoxy resin that is liquid at 25°C may contain at least one liquid epoxy resin selected from, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, bisphenol S type epoxy resin, naphthalene diol type epoxy resin, hydrogenated bisphenol A type epoxy resin, and aminoglycidyl ether type epoxy resin.

[0098] Epoxy group-containing compounds that are liquid at 25°C can also be obtained as commercial products. For example, they are sold by Nippon Steel Chemical Co., Ltd. as liquid bisphenol A type epoxy resin and liquid bisphenol F type epoxy resin. For example, as liquid bisphenol F type epoxy resin, a product name "YDF-8170C" (epoxy equivalent 165, viscosity 1,000 to 1,500 mPa·s) can be used. As epoxy compounds, the ADEKA Glysilol (product name) series manufactured by ADEKA Corporation can be mentioned. For example, a product name "ADEKA Glysilol ED-503G" (epoxy equivalent 135, viscosity 15 mPa·s) can be used.

[0099] The paste may further contain other resins in addition to the epoxy group-containing compound. The other resins may contain at least one selected from the group consisting of thermosetting resins (excluding epoxy resins) and thermoplastic resins. The thermosetting resin may be, for example, at least one selected from the group consisting of phenolic resins, acrylic resins, polyimide resins, and polyamideimide resins. When a phenolic resin is used in addition to the epoxy group-containing compound, the phenolic resin can also function as a curing agent for the epoxy group-containing compound.

[0100] The thermoplastic resin may be, for example, at least one selected from the group consisting of acrylic resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, and polyethylene terephthalate. The resin component may further contain a silicone resin in addition to the epoxy group-containing compound.

[0101] When the paste contains a resin other than the epoxy group-containing compound, it is preferable to adjust the content of the other resin within a range that does not reduce the effect of the epoxy group-containing compound. For example, the content of the other resin may be 50 mass % or less, 30 mass % or less, or 10 mass % or less based on the total mass of the resin in the paste. The blending amount can be adjusted within a range in which the viscosity of the mixture of the epoxy group-containing compound and the other resin is 50 Pa·s or less at 25°C. The above viscosity is a value measured using an E-type viscometer under the following conditions: temperature: 25°C, cone plate type: SPP, cone angle: 1°34', and rotation speed: 2.5 rpm. As the E-type viscometer, for example, a TV-33 type viscometer manufactured by Toki Sangyo Co., Ltd. can be used.

[0102] The curing agent may be a compound that imparts appropriate viscosity to the paste and reacts with the epoxy group of the epoxy group-containing compound to form a cured product. The curing agent may be a well-known curing agent that is generally used as a curing agent for epoxy resins. Examples of the curing agent include phenol-based curing agents, acid anhydride-based curing agents, and amine-based curing agents.

[0103] Curing agents are classified into curing agents that cure epoxy resins in a temperature range from low temperature to room temperature, and heat-curing curing agents that cure epoxy resins by heating. Examples of curing agents that cure epoxy resins in a temperature range from low temperature to room temperature include aliphatic polyamines, polyaminoamides, and polymercaptans. Examples of heat-curing curing agents include aromatic polyamines, acid anhydrides, phenol novolac resins, and dicyandiamide (DICY). When a curing agent that cures epoxy resins in a temperature range from low temperature to room temperature is used, the glass transition point of the cured product of the epoxy resin is low, and the cured product of the epoxy resin tends to be soft. As a result, the insulating magnetic layer formed from the paste also tends to be soft. From the viewpoint of improving the heat resistance and mechanical strength of the insulating magnetic layer, it is preferable that the curing agent contains a heat-curing curing agent.

[0104] Among the heat-curing curing agents, a liquid curing agent at 25°C can be used from the viewpoint of reducing the viscosity of the paste. As the liquid curing agent, for example, at least one selected from the group consisting of aliphatic polyamines, polymercaptans, aromatic polyamines, acid anhydrides, and imidazole-based curing agents can be used. If the increase in viscosity of the paste can be suppressed, a solid curing agent at 25°C may be used, or a liquid curing agent and a solid curing agent may be used in combination. As the solid curing agent, for example, dicyandiamide, tertiary amines, imidazole-based curing agents, and imidazoline-based curing agents can be used. The exemplified solid curing agents are polyfunctional or act catalytically, so that they can function sufficiently even in small amounts.

[0105] The curing agent may include at least one selected from the group consisting of amine-based curing agents, imidazole-based curing agents, and imidazoline-based curing agents. The curing agent may include at least an amine-based curing agent. The amine-based curing agent (more specifically, a tertiary amine), the imidazole-based curing agent, and the imidazoline-based curing agent may also be used as a curing accelerator in combination with other curing agents.

[0106] The amine-based curing agent may be a compound having at least two amino groups in the molecule. The amine-based curing agent includes at least one selected from the group consisting of aliphatic amines and aromatic amines. Examples of the aliphatic amine compound include diethylenetriamine, triethylenetetramine, n-propylamine, 2-hydroxyethylaminopropylamine, cyclohexylamine, and 4,4'-diamino-dicyclohexylmethane. Examples of the aromatic amine compound include 4,4'-diaminodiphenylmethane, 2-methylaniline, an amine compound represented by the following formula (1), and an amine compound represented by the following formula (2). [ka] [ka]

[0107] The imidazole-based curing agent is a compound having an imidazole skeleton, and may be an imidazole-based compound in which hydrogen atoms in the molecule are substituted with a substituent. The imidazole-based curing agent may be a compound having an imidazole skeleton, such as an alkyl group-substituted imidazole. Examples of the imidazole-based curing agent include imidazole, 2-methylimidazole, 2-ethylimidazole, and 2-isopropylimidazole. The imidazole-based curing agent may be a commercially available product such as "Curezol 2E4MZ" (2-ethyl-4-methylimidazole) manufactured by Shikoku Chemical Industry Co., Ltd.

[0108] The imidazoline-based curing agent is a compound having an imidazoline skeleton, and may be an imidazoline-based compound in which hydrogen atoms in the molecule are substituted with a substituent. The imidazoline-based curing agent may be a compound having an imidazoline skeleton, such as an alkyl group-substituted imidazoline. Examples of the imidazoline-based curing agent include imidazoline, 2-methylimidazoline, and 2-ethylimidazoline.

[0109] From the viewpoint of compatibility with epoxy resins that are liquid at 25°C and storage stability, the curing agent may contain an aromatic amine. The aromatic ring of the aromatic amine may have a substituent other than an amino group. For example, it may have an alkyl group having 1 to 5 carbon atoms, or an alkyl group having 1 or 3 carbon atoms. The number of aromatic rings in the aromatic amine may be one or two or more. When the number of aromatic rings is two or more, the aromatic rings may be bonded to each other by a single bond or via a linking group such as an alkylene group.

[0110] From the viewpoint of the viscosity of the paste, it is preferable that the curing agent contains a liquid aromatic amine. For example, at least one selected from the group consisting of the compound represented by the above formula (1) and the compound represented by the above formula (2) can be used.

[0111] Liquid aromatic amines that can be used as curing agents are also available as commercial products, such as "Grade: jER Cure WA" manufactured by Mitsubishi Chemical Corporation and "Kayahard AA" manufactured by Nippon Kayaku Co., Ltd.

[0112] The content of the curing agent in the paste can be set in consideration of the ratio between the equivalent number of the epoxy group of the epoxy group-containing compound such as the epoxy resin and the equivalent number of the active group in the curing agent. For example, the ratio of the curing agent to 1 equivalent of the epoxy group of the epoxy group-containing compound may be 0.5 to 1.5 equivalents, 0.9 to 1.4 equivalents, or 1.0 to 1.2 equivalents.

[0113] When the ratio of the active group in the curing agent is 0.5 equivalents or more, the amount of OH per unit weight of the epoxy resin after heat curing is reduced, and the curing speed of the epoxy resin can be prevented from decreasing. In addition, the glass transition temperature of the obtained cured product and the elastic modulus of the cured product can be prevented from decreasing. Furthermore, the insulation reliability of the cured product can be prevented from decreasing due to unreacted resin components in the binder resin. On the other hand, when the ratio of the active group in the curing agent is 1.5 equivalents or less, the mechanical strength of the insulating magnetic layer formed from the paste after heat curing can be prevented from decreasing. In addition, the insulation property of the cured product can be prevented from decreasing due to unreacted curing agent.

[0114] The paste may further include a hardening accelerator as necessary. The paste may include a magnetic powder, an epoxy group-containing compound, a hardener, and a hardening accelerator. In another embodiment, the paste may further include additives such as a coupling agent and a flame retardant in addition to the above components.

[0115] The curing accelerator is not limited as long as it is a compound that can accelerate the curing reaction between the epoxy resin and the curing agent. Examples of the curing accelerator include tertiary amines, imidazole curing accelerators, imidazoline curing accelerators, and phosphorus compounds. The imidazole curing accelerator and the imidazoline curing accelerator may be the compounds exemplified above as the imidazole curing agent and the imidazoline curing agent. Among the liquid curing agents, when a liquid acid anhydride is used, a curing accelerator can be used in combination. The paste may contain one or more curing accelerators. When a curing accelerator is used, the mechanical strength of the insulating magnetic layer formed from the paste can be improved, and the curing temperature of the paste can be easily reduced.

[0116] The amount of the curing accelerator is not particularly limited as long as it is an amount that can obtain a curing acceleration effect. However, from the viewpoint of improving the curing property and fluidity of the paste when absorbing moisture, the amount of the curing accelerator may be 0.001 parts by mass or more with respect to 100 parts by mass of the epoxy resin and the curing agent in total. The amount of the curing accelerator may be 0.01 parts by mass or more, or 0.1 parts by mass or more. On the other hand, the amount of the curing accelerator may be 5 parts by mass or less, 4 parts by mass or less, or 3 parts by mass or less. When the amount of the curing accelerator is 0.001 parts by mass or more, a sufficient curing acceleration effect can be easily obtained. When the amount of the curing accelerator is 5 parts by mass or less, excellent storage stability can be easily obtained in the paste.

[0117] When a coupling agent is used, the dispersibility of the magnetic powder in the paste is improved and the paste viscosity is easily controlled. In addition, the adhesion between the binder resin and the magnetic powder is easily improved. Furthermore, the adhesion, flexibility, and mechanical strength of the insulating magnetic layer formed from the paste to the conductor wiring are easily improved. The coupling agent may be, for example, at least one selected from the group consisting of silane-based compounds (silane coupling agents), titanium-based compounds, aluminum compounds (aluminum chelates), and aluminum / zirconium-based compounds. The silane coupling agent may be, for example, at least one selected from the group consisting of epoxy silane, mercapto silane, amino silane, alkyl silane, ureido silane, acid anhydride silane, and vinyl silane. The silane coupling agent may be an aminophenyl-based silane coupling agent. The paste may contain at least one of the above coupling agents, or may contain two or more of the above coupling agents.

[0118] For the sake of environmental safety, recyclability, moldability, and low cost of the paste, the paste may contain a flame retardant. The flame retardant may be, for example, at least one selected from the group consisting of bromine-based flame retardants, phosphorus-based flame retardants, hydrated metal compound-based flame retardants, silicone-based flame retardants, nitrogen-containing compounds, hindered amine compounds, organometallic compounds, and aromatic engineering plastics. The paste may contain one or more of the flame retardants exemplified above.

[0119] The paste may contain an organic solvent as necessary. The organic solvent is not particularly limited. For example, an organic solvent capable of dissolving the binder resin may be used. The organic solvent may be, for example, at least one selected from the group consisting of acetone, methyl ethyl ketone, methyl isobutyl ketone, benzene, toluene, carbitol acetate, butyl carbitol acetate, cyclohexanone, and xylene. From the viewpoint of workability, the organic solvent may be liquid at room temperature (25°C). From the viewpoint of workability, the boiling point of the organic solvent may be 50°C or more and 160°C or less.

[0120] When the paste contains an organic solvent, the content of the organic solvent may be 5% by mass or less, 3% by mass or less, or 1% by mass or less based on the total mass of the paste. The paste may be substantially free of organic solvent. In this specification, "substantially free" means that no organic solvent is intentionally added to the paste. Therefore, the paste may contain, for example, an organic solvent that was used during the production of the resin and remains in the resin.

[0121] The viscosity of the paste may be 1 Pa·s or more, 10 Pa·s or more, or 100 Pa·s or more. By adjusting the viscosity to 1 Pa·s or more, dripping after application can be suppressed, and the pattern shape can be easily prevented from collapsing after printing. In addition, settling of the magnetic powder in the paste can be suppressed, and the deterioration of the application property over time after stirring the paste can be easily improved. On the other hand, the viscosity of the paste may be 600 Pa·s or less, 400 Pa·s or less, or 200 Pa·s or less. By adjusting the viscosity to 600 Pa·s or less, the paste becomes fluid, and good application property can be easily obtained.

[0122] When the paste is applied to screen printing, the viscosity of the paste may be 10 Pa·s to 400 Pa·s, 50 Pa·s to 300 Pa·s, or 100 Pa·s to 250 Pa·s. When the viscosity is adjusted to the above range, the occurrence of a defect in which the paste does not pass through the openings of the plate in screen printing can be suppressed. The viscosity of the paste can be freely adjusted by the structure and characteristics of the epoxy group-containing compound, the structure and characteristics of the curing agent, and the combination and compounding ratio of these, as well as the structure and compounding ratio of additives such as a curing accelerator and a coupling agent. The paste may contain additives such as a viscosity modifier, a thixotropic agent, and a dispersion stabilizer.

[0123] <Wiring board and method of manufacturing same> The wiring board includes a substrate, a conductor wiring provided on the substrate, and an insulating magnetic layer that covers at least a portion of the periphery of the conductor wiring and is made of an insulator containing a magnetic material. A method for manufacturing the wiring board will be described below.

[0124] The method for manufacturing a wiring board of this embodiment includes the steps of: (I) forming an insulating material layer on a substrate; (II) forming an opening in the insulating material layer that opens to the side opposite the substrate; (III) forming an insulating magnetic layer on at least the inner surface of the opening; and (IV) forming conductor wiring on the insulating magnetic layer.

[0125] In the method for manufacturing a wiring board of this embodiment, the above-mentioned step (III) may be a step of forming an insulating magnetic layer on the inner side of the opening and on the surface of the insulating material layer other than the opening, and the above-mentioned step (IV) may include a step of producing a laminate in which a conductor layer is formed on the insulating magnetic layer, and a step of forming conductor wiring by removing a portion of the laminate on the opposite side to the substrate.

[0126] First embodiment 1 and 2 are schematic cross-sectional views for explaining a first embodiment of a method for manufacturing a wiring board. The method for manufacturing a wiring board of the first embodiment includes a step (I) of forming an insulating material layer 2 on a substrate 10, a step (II-1) of forming an opening H1 in the insulating material layer 2 that leads to the substrate 10, a step (III-1) of forming an insulating magnetic layer 30 on the surface of the substrate 10 at the opening H1 and on the surface of the insulating material layer 2a including the opening, and a step (IV) of forming a conductor wiring 20 on the insulating magnetic layer 30.

[0127] In the first embodiment, step (IV) can include a step (IV-1) of producing a laminate 50 in which a conductor layer 6 is formed on an insulating magnetic layer 30, and a step (IV-2) of removing a portion of the laminate 50 on the side opposite the substrate 10.

[0128] Furthermore, step (IV-1) may include a step (IV-1a) of forming a plating seed layer 4 on the surface of the insulating magnetic layer 30, and a step (IV-1b) of filling at least the opening H1 with a conductive material by electrolytic plating.

[0129] [Process (I)] In step (I), an insulating material layer 2 is formed on a substrate 10 (see FIG. 1(a)). For example, the substrate 10 may be one obtained by laminating several sheets of known prepregs together and subjecting them to a pressurized heat treatment. Such prepregs may be ones produced by impregnating a prepared resin varnish into a fiber base material (reinforced fiber) such as glass fiber or organic fiber by a known method, and examples of such prepregs include glass epoxy composite substrates. A metal substrate or a ceramic substrate may be used as a core material to which the prepregs are laminated. Furthermore, for the substrate 10, known low-dielectric substrates may be used, such as substrates using low-dielectric resin materials such as polyimide resins, fluorine resins, and liquid crystal polymers (LCPs).

[0130] Examples of the resin material constituting the substrate 10 include thermosetting resins, thermoplastic resins, etc. The resin materials may be used alone or in combination of two or more kinds.

[0131] Examples of the thermosetting resin include polycarbonate resin, thermosetting polyimide resin, thermosetting fluorinated polyimide resin, epoxy resin, phenol resin, urea resin, melamine resin, diallyl phthalate resin, silicone resin, thermosetting urethane resin, fluororesin, liquid crystal polymer, etc. Examples of the fluororesin include polymers of fluorine-containing olefins such as polytetrafluoroethylene (PTFE).

[0132] Examples of thermoplastic resins include olefin resins, acrylic resins, polystyrene resins, polyester resins, polyacrylonitrile resins, maleimide resins, polyvinyl acetate resins, ethylene-vinyl acetate copolymers, polyvinyl alcohol resins, polyamide resins, polyvinyl chloride resins, polyacetal resins, polyphenylene oxide resins, polyphenylene sulfide resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polyarylsulfone resins, thermoplastic polyimide resins, thermoplastic fluorinated polyimide resins, thermoplastic urethane resins, polyetherimide resins, polymethylpentene resins, cellulose resins, liquid crystal polymers, and ionomers.

[0133] The substrate 10 may be a single layer or a multilayer. The substrate may have an adhesive layer on the surface.

[0134] The thickness of the substrate 10 may be from 10 μm to 1 mm.

[0135] In step (I), it is preferable to use a photosensitive resin material as the material constituting the insulating material layer 2, since this makes it possible to easily form fine openings H1 or H2 by a photolithography process in step (II-1) or step (II-2) described below.

[0136] The photosensitive insulating material may be in the form of a liquid or film, and a film-like photosensitive insulating material is preferred from the viewpoints of film thickness flatness and cost. In addition, the photosensitive insulating material may contain a filler (filling material) having an average particle size of 500 nm or less (more preferably 50 to 200 nm) in order to form fine wiring. The filler content of the photosensitive insulating material may be 0 to 70 parts by mass or 10 to 50 parts by mass relative to 100 parts by mass of the photosensitive insulating material excluding the filler.

[0137] When using a film-type photosensitive insulating material, it is preferable to carry out the lamination process at as low a temperature as possible. From the viewpoint of ease of handling and minimizing warping after lamination, a photosensitive insulating film that can be laminated at 40°C to 120°C can be used.

[0138] The thermal expansion coefficient of the insulating material layer 2 after curing is set to 80×10 -6 / K or less, and high reliability is obtained. -6 / K or less. In addition, in terms of the stress relaxation of the insulating material and the ability to obtain a highly precise pattern, -6 / K or more.

[0139] The thickness of the insulating material layer 2 can be appropriately set according to the thickness of the conductor wiring to be formed, and may be, for example, 30 μm or less, 20 μm or less, 10 μm or less, 5 μm or less, or 3 μm or less. From the viewpoint of insulation reliability, the thickness of the insulating material layer 2 may be 1 μm or more.

[0140] [Process (II-1)] In step (II-1), an opening H1 that leads to the substrate 10 is formed in the insulating material layer 2. As a result, an insulating material layer 2a including the opening H1 is formed on the substrate 10 (see FIG. 1(b)). The opening H1 refers to a recessed portion that opens in the thickness direction of the insulating material layer 2 with respect to the surface of the insulating material layer 2 and reaches the surface of the substrate 10, and includes the inner wall (side surface, bottom surface, etc.) of this opening portion. The opening H1 can also be called a groove portion. As shown in FIG. 1(b), the opening H1 is preferably formed to reach the surface of the substrate 10, that is, the opening H1 is preferably composed of a side surface made of the insulating material layer 2a and a bottom surface made of the surface of the substrate 10. The opening shape of the opening H1 can be set according to the pattern of the conductor wiring to be formed.

[0141] Examples of the method for forming the opening H1 include laser ablation, photolithography, imprinting, and the like. Among these methods, from the viewpoint of miniaturization and cost, it is preferable to form the insulating material layer 2 made of a photosensitive resin material in the step (I) and form the opening H1 by a photolithography process (exposure and development). As the exposure method for the photosensitive resin material, a normal projection exposure method, contact exposure method, direct drawing exposure method, and the like can be used, and as the development method, it is preferable to use an alkaline aqueous solution of sodium carbonate or TMAH (tetramethylammonium hydroxide). After forming the opening H1 in the insulating material layer 2, the insulating material may be further heated and cured. The heating temperature is 100°C to 200°C, and the heating time is between 30 minutes and 3 hours. In addition, if there is a residue of the insulating material layer 2 on the opened surface, the residue can be removed by oxygen plasma treatment, argon plasma treatment, or nitrogen plasma treatment.

[0142] [Process (III-1)] In step (III-1), an insulating magnetic layer 30 is formed on the surface of the substrate 10 at the opening H1 and on the surface of the insulating material layer 2a including the opening. The insulating magnetic layer 30 is made of an insulator containing a magnetic material. The magnetic material may be dispersed in the insulating magnetic layer 30. Note that in step (III-1), the surface of the substrate 10 at the opening H1 and the side surface of the insulating material layer 2a are the inner surface of the opening H1.

[0143] The insulating magnetic layer 30 can be formed by the insulating magnetic layer forming composition described above. Specifically, for example, a method of forming a layer made of the insulating magnetic layer forming composition by applying the insulating magnetic layer forming composition containing a magnetic material onto the surface of the substrate 10 at the opening H1 and onto the surface of the insulating material layer 2a including the opening, or laminating a sheet (e.g., a film-like sheet) made of the insulating magnetic layer forming composition containing a magnetic material, and then curing the layer can be mentioned.

[0144] The method for applying the composition for forming the insulating magnetic layer is not particularly limited, but examples include screen printing, transfer printing, offset printing, jet printing, a dispenser, a jet dispenser, a needle dispenser, a comma coater, a slit coater, a die coater, a gravure coater, a slit coat, letterpress printing, intaglio printing, gravure printing, stencil printing, soft lithography, a bar coat, an applicator, a particle deposition method, a spray coater, a spin coater, a dip coater, and the like.

[0145] The sheet made of the insulating magnetic layer forming composition can be formed, for example, by applying the insulating magnetic layer forming composition onto a support film by the above-mentioned application method. The lamination method of the sheet made of the insulating magnetic layer forming composition is not particularly limited, but a roll laminator, a diaphragm type laminator, a vacuum roll laminator, a vacuum diaphragm type laminator, etc. can be used.

[0146] The insulating magnetic layer forming composition can be cured, for example, by heating. The insulating magnetic layer forming composition can be cured by drying the insulating magnetic layer forming composition, or when the insulating magnetic layer forming composition contains a thermosetting resin, the insulating magnetic layer forming composition can be thermally cured. The heating temperature and heating time can be appropriately adjusted depending on the type of solvent contained in the insulating magnetic layer forming composition, the type of thermosetting resin, etc.

[0147] From the viewpoint of ease of signal propagation, the coating thickness of the insulating magnetic layer 30 may be 0.1 to 100 μm, may be 0.2 to 30 μm, or may be 0.5 to 10 μm.

[0148] In this specification, the coating thickness of the insulating magnetic layer 30 means the following (i) when the insulating magnetic layer 30 is provided away from the conductor wiring 20, and the following (ii) when the insulating magnetic layer 30 is provided in contact with the conductor wiring 20. (i) The distance between point A on the surface of the insulating magnetic layer 30 facing the conductor wiring 20 and point B, where a line passing through point A and extending from point A to the conductor wiring 20 in the shortest distance intersects with the surface of the insulating magnetic layer 30 opposite the conductor wiring 20. (ii) The thickness in a direction perpendicular to the interface between the insulating magnetic layer 30 and the conductor wiring 20 .

[0149] From the viewpoint of suppressing transmission loss, the relative permeability of the insulating magnetic layer 30 may be 2-1,000, 10-1,000, or 20-1,000.

[0150] From the viewpoint of suppressing transmission loss, the insulating magnetic layer 30 may have a relative dielectric constant of 1-30, 1-20, or 1-10.

[0151] [Process (IV-1)] In step (IV-1), a laminate 50 in which a conductive layer 6 is formed on an insulating magnetic layer 30 can be produced by steps (IV-1a) and (IV-1b) (see FIG. 2(b)).

[0152] [Process (IV-1a)] In step (IV-1a), a plating seed layer 4 is formed on the surface of the insulating magnetic layer 30 (see FIG. 2(a)). This plating seed layer 4 serves as a power supply layer for electrolytic plating carried out in step (IV-1b). The plating seed layer 4 can be formed by, for example, electroless plating or sputtering. The conductor (e.g., metal) constituting the plating seed layer 4 may be the same conductor (e.g., metal) as the conductor wiring 20. The plating seed layer 4 may have a thickness of, for example, 0.001 to 5 μm.

[0153] [Process (IV-1b)] In the step (IV-1b), subsequent to the step (IV-1a), at least the openings H1 are filled with a conductive material by electrolytic plating.

[0154] Specifically, for example, electrolytic copper plating can be performed using the plating seed layer 4 as a power supply layer, whereby the opening H1 is filled with a conductive material (for example, a copper-containing material), and further a conductor layer 6 is formed so as to cover the upper surface of the insulating material layer 2a (see FIG. 2(b)).

[0155] In the first embodiment, a step (PreIV-1a) of modifying the surface of the insulating magnetic layer 30 may be provided before providing the plating seed layer.

[0156] [Process (PreIV-1a)] In the process (PreIV-1a), the surface of the insulating magnetic layer 30 can be modified. By roughening the surface of the insulating magnetic layer 30 to the nano level by modification, it is possible to achieve both excellent adhesion between the insulating magnetic layer 30 and the plating seed layer 4 and excellent formability of the conductor wiring formed thereafter. Methods for modification include ultraviolet irradiation, electron beam irradiation, ozone water treatment, corona discharge treatment, plasma treatment, and the like. Among these methods, ultraviolet irradiation is preferred because it does not require vacuum equipment and does not generate waste liquid, etc. Examples of ultraviolet ray irradiation lamps used for modification include high pressure mercury lamps, low pressure mercury lamps, vacuum ultraviolet excimer lamps, and the like, but low pressure mercury lamps or excimer lamps, which have a large activation effect, are preferred.

[0157] The modification may be performed in air or in an oxygen atmosphere. The temperature condition for the modification is 25°C to 100°C, and from the viewpoint of accelerating the reactivity, it may be 40°C to 100°C or 60°C to 100°C. The contact angle of the surface of the insulating magnetic layer 30 after the modification with pure water may be 40 degrees or less, 20 degrees or less, or 10 degrees or less. The modification treatment may be repeated multiple times.

[0158] In the step (IV-1), when a conductive layer is formed on the insulating magnetic layer by, for example, electroless plating or sputtering, the formation of the plating seed layer 4 can be omitted.

[0159] [Process (IV-2)] In step (IV-2), a portion of the laminate 50 on the side opposite to the substrate 10 is removed. This forms the conductor wiring 20 on the insulating magnetic layer 30 (see FIG. 2(c)). For example, a portion of the plating seed layer and the conductor layer, a portion of the insulating magnetic layer, and a portion of the insulating material layer can be removed so that the insulating material layer, the insulating magnetic layer, and the conductor layer are planarized on the surface opposite to the substrate.

[0160] The method of removing a part of the laminate on the side opposite to the substrate includes a method of grinding or polishing the surface of the laminate on the side opposite to the substrate. The grinding method and polishing method are not particularly limited, and may be, for example, grinding by a flycut method, polishing by CMP (Chemical Mechanical Polishing), etching, etc. These methods may also be applied in combination.

[0161] For CMP, a known method using a slurry containing abrasive grains and a liquid medium can be used. For the fly-cut method, a grinding device using a diamond tool can be used, for example, an automatic surface planer (manufactured by Disco Corporation, product name "DAS8930") compatible with 300 mm wafers can be used.

[0162] 2(c) is obtained. The wiring board 100 includes the substrate 10, and a conductor wiring 20 provided on the substrate 10, the conductor wiring 20 having a bottom surface S2 located on the substrate 10 side, a top surface S1 located on the opposite side to the substrate 10, and a pair of side surfaces S3a, S3b located between the bottom surface S2 and the top surface S1, and an insulating magnetic layer 30 covering the bottom surface S2 and the pair of side surfaces S3a, S3b of the conductor wiring 20.

[0163] Second Embodiment 3 and 4 are schematic cross-sectional views for explaining a second embodiment of the method for manufacturing a wiring board. The method for manufacturing a wiring board of the second embodiment includes a step (I) of forming an insulating material layer 2 on a substrate 10, a step (II-2) of forming an opening H2 in the insulating material layer 2, the opening H2 being open on the side opposite to the substrate 10 and having a bottom surface, a step (III-2) of forming an insulating magnetic layer 30 on the inner side surface of the opening H2 and on the surface of the insulating material layer 2c other than the opening, and a step (IV) of forming a conductor wiring 20 on the insulating magnetic layer 30.

[0164] In the second embodiment, step (IV) can include a step (IV-3) of producing a laminate 52 in which a conductor layer 6 is formed on an insulating magnetic layer 30, and a step (IV-4) of removing a portion of the surface of the laminate 52 opposite the substrate.

[0165] Furthermore, step (IV-3) may include a step (IV-3a) of forming a plating seed layer 4 on the surface of the insulating magnetic layer 30, and a step (IV-3b) of filling at least the opening H2 with a conductive material by electrolytic plating.

[0166] Step (I) in the second embodiment is similar to step (I) in the first embodiment (see FIG. 3(a)).

[0167] [Process (II-2)] In step (II-2), an opening H2 is formed in the insulating material layer 2, opening on the side opposite to the substrate 10 and having a bottom surface. As a result, an insulating material layer 2c including the opening H2 is formed on the substrate 10 (see FIG. 3(b)). The opening H2 refers to a recessed portion that is open in the thickness direction of the insulating material layer 2 and has a bottom surface relative to the surface of the insulating material layer 2, and includes the inner walls (side surfaces, bottom surface, etc.) of this opening portion. The opening H2 can also be called a groove portion. The opening shape of the opening H2 can be set according to the pattern of the conductor wiring to be formed.

[0168] The opening H2 can be formed by laser ablation, photolithography, imprinting, or the like.

[0169] [Process (III-2)] In step (III-2), an insulating magnetic layer 30 is formed on the inner side surface of the opening H2 and on the surface of the insulating material layer 2c other than the opening (see FIG. 3(c)). The insulating magnetic layer 30 can be formed in the same manner as in step (III-1).

[0170] [Process (IV-3)] In step (IV-3), a laminate in which a conductor layer 6 is formed on an insulating magnetic layer 30 can be produced by steps (IV-3a) and (IV-3b) (see FIG. 4(b)).

[0171] [Process (IV-3a)] In step (IV-3a), a plating seed layer 4 is formed on the surface of the insulating magnetic layer 30 (see FIG. 4(a)). The plating seed layer 4 can be formed in the same manner as in step (IV-1a).

[0172] [Process (IV-3b)] In step (IV-3b), following step (IV-3a), at least the openings H2 are filled with a conductive material by electrolytic plating. Specifically, for example, electrolytic copper plating can be performed using the plating seed layer 4 as a power supply layer. As a result, the openings H2 are filled with a conductive material (for example, a copper-containing material), and a conductor layer 6 is formed so as to cover the upper surface of the insulating material layer 2c (see FIG. 4(b)).

[0173] In the second embodiment, a step (PreIV-3a) of modifying the surface of the insulating magnetic layer 30 may be provided before providing the plating seed layer. The surface of the insulating magnetic layer 30 may be modified in the same manner as in the step (PreIV-1a).

[0174] In the step (IV-3), when a conductive layer is formed on the insulating magnetic layer by, for example, electroless plating or sputtering, the formation of the plating seed layer 4 can be omitted.

[0175] [Process (IV-4)] In step (IV-4), a portion of the laminate 52 on the side opposite to the substrate 10 is removed. This results in the formation of the conductor wiring 20 on the insulating magnetic layer 30 (see FIG. 4(c)). For example, a portion of the plating seed layer and the conductor layer, a portion of the insulating magnetic layer, and a portion of the insulating material layer can be removed so that the insulating material layer, the insulating magnetic layer, and the conductor layer are planarized on the surface opposite to the substrate.

[0176] The method for removing the part of the laminate opposite to the substrate can be the same as in step (IV-2).

[0177] 4(c) is obtained. The wiring board 110 includes the substrate 10, and a conductor wiring 20 provided on the substrate 10, the conductor wiring 20 having a bottom surface S2 located on the substrate 10 side, a top surface S1 located on the opposite side to the substrate 10, and a pair of side surfaces S3a, S3b located between the bottom surface S2 and the top surface S1, and an insulating magnetic layer 30 covering the bottom surface S2 and the pair of side surfaces S3a, S3b of the conductor wiring 20. EXAMPLES

[0178] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0179] <Preparation of composition for forming insulating magnetic layer> All the raw materials in the ointment container, which were mixed according to the composition shown in Table 1, were stirred and mixed with a planetary stirrer ("ARE-500" manufactured by Thinky Corporation) to obtain binder resin varnish I. In the stirring and mixing process, the revolution speed of the planetary stirrer was first maintained at 2000 rpm, and the mixture was stirred and mixed for 300 seconds. Next, the revolution of the planetary stirrer was stopped, and the mixture in the container was stirred using a medicine spoon, after which the revolution speed of the planetary stirrer was again maintained at 2000 rpm, and the mixture was stirred and mixed for 120 seconds.

[0180] [Table 1]

[0181] Details of each component shown in Table 1 are given below. YDF-8170C: Trade name of Nippon Steel Chemical & Material Co., Ltd., Bisphenol F type epoxy resin jER Cure WA ("jER Cure" is a registered trademark): A product name of Mitsubishi Chemical Corporation, an amine-based epoxy resin hardener 2E4MZ: Curing accelerator manufactured by Shikoku Kasei Co., Ltd., 2-ethyl-4-methylimidazole Teisan Resin HTR-860-P3: Trade name of Nagase ChemteX Corporation, acrylic resin (cyclohexanone solution) KBM-573: Trade name of Shin-Etsu Silicone Co., Ltd., N-phenyl-3-aminopropyltrimethoxysilane

[0182] Next, 8.5 parts by mass of binder resin varnish I and 73 parts by mass of magnetic powder (SAP-2D(C): manufactured by Shinto Kogyo Co., Ltd.) were weighed out and placed in a 50 ml ointment container. The binder resin varnish I and magnetic powder in the ointment container were stirred for 45 seconds using a revolutionary stirrer at a revolution speed of 2000 rpm. Next, the revolution of the revolutionary stirrer was stopped, and the mixture in the container was stirred using a medicine spoon, and then stirred twice for 45 seconds at a revolution speed of 2000 rpm of the revolutionary stirrer. This resulted in a paste-like insulating magnetic layer forming composition.

[0183] <Preparation of photosensitive insulating film for forming insulating material layer> A photosensitive insulating film used to form an insulating material layer was prepared by the following procedure.

[0184] As a photoreactive resin containing a carboxyl group and an ethylenically unsaturated group, 50 parts by mass of acid-modified cresol novolac epoxy acrylate (CCR-1219H, Nippon Kayaku Co., Ltd., product name), 5 parts by mass of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (Darocur TPO, BASF Japan Ltd., product name) and 5 parts by mass of ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(o-acetyloxime) (Irgacure OXE-02, BASF Japan Ltd., product name) as photopolymerization initiators, 10 parts by mass of biphenol-type epoxy resin (YX-4000, Mitsubishi Chemical Corporation, product name) as a thermosetting agent component, and silica (average particle size: 50 nm, silane coupling treatment with vinylsilane) as an inorganic filler were mixed to prepare a photosensitive resin composition. The inorganic filler was mixed in an amount of 10 parts by volume per 100 parts by volume of the resin. The particle size distribution of the inorganic filler was measured using a dynamic light scattering nanotrack particle size distribution meter "UPA-EX150" (manufactured by Nikkiso Co., Ltd.) and a laser diffraction scattering microtrack particle size distribution meter "MT-3100" (manufactured by Nikkiso Co., Ltd.), and it was confirmed that the maximum particle size of the inorganic filler was 1 μm or less.

[0185] The solution of the photosensitive resin composition obtained above was applied onto the surface of a polyethylene terephthalate film (G2-16, Teijin Limited, product name, thickness: 16 μm). This was dried at 100° C. for about 10 minutes using a hot air convection dryer to obtain a photosensitive insulating film. The thickness of the photosensitive insulating film was 50 μm.

[0186] <Preparation of wiring board> Example 1 A photosensitive insulating film was placed on a substrate (glass cloth substrate (size: 200 mm square, thickness 1.5 mm)). It was then pressed using a press-type vacuum laminator (MVLP-500, manufactured by Meiki Seisakusho Co., Ltd.). The pressing conditions were: press hot plate temperature 80°C, vacuum time 20 seconds, lamination press time 60 seconds, air pressure 4 kPa or less, and compression pressure 0.4 MPa. This provided an insulating material layer 20 μm thick on the substrate.

[0187] Next, the insulating material layer was subjected to the following exposure and development processes to form an opening (depth: 50 μm, width: 200 μm). Exposure process: A phototool with a pattern formed on the insulating material layer was attached to the insulating material layer, and an i-line stepper exposure machine (product name: S6CK type exposure machine, lens: ASC3 (Ck), manufactured by Therma Precision Co., Ltd.) was used to perform exposure at 30 mJ / cm. 2 The sample was exposed to an energy dose of 1000 .mu.m. Development treatment: After the exposure treatment, spray development was carried out with a 1% by mass aqueous solution of sodium carbonate at 30° C. for 45 seconds to provide openings.

[0188] Furthermore, a mask exposure machine (EXM-1201 type exposure machine, manufactured by Oak Manufacturing Co., Ltd.) was used to expose the surface of the insulating material layer after the development process at 2000 mJ / cm 2 The post-UV exposure was performed with an energy amount of 10 ...

[0189] The insulating magnetic layer-forming composition obtained above was spray-coated on the inner side of the opening and on the surface of the insulating material layer other than the opening, and then dried and cured. This formed an insulating magnetic layer (thickness: 5 μm). Next, a plating seed layer (thickness: 0.5 μm) made of copper was formed on the insulating magnetic layer by electroless plating.

[0190] Next, a plating layer (thickness: 35 μm) made of copper was formed by plating on the formed plating seed layer, to obtain a laminate A (substrate / insulating material layer / insulating magnetic layer / plating seed layer / conductor layer (plating layer)).

[0191] The side of the laminate A opposite to the substrate was polished by a fly-cut method to remove a part of the insulating material layer, a part of the insulating magnetic layer, a part of the plating seed layer, and a part of the conductor layer. This resulted in a wiring board including the substrate, a conductor wiring (thickness: 30 μm, width: 190 μm) provided on the substrate, and a 5 μm-thick insulating magnetic layer covering the bottom surface, top surface, and a pair of side surfaces of the conductor wiring. In this way, a wiring board having a configuration similar to that of FIG. 2(c) was obtained.

[0192] Comparative Example 1 Except for not providing an insulating magnetic layer, a wiring board was obtained in the same manner as in Example 1. In order to make the size of the conductor wiring the same as in Example 1, an opening (depth: 50 μm, width: 190 μm) smaller than the thickness of the insulating magnetic layer was provided.

[0193] <Evaluation of transmission loss in wiring boards> The transmission loss of the wiring board prepared above was evaluated by a triplate line resonator method. A vector network analyzer (Keysight Technologies, Inc., E8364B) was used for the triplate line resonator method. The measurement conditions were line width: 0.15 mm, line length: 10 mm, characteristic impedance: about 50 Ω, frequency: 10, 30, 50 GHz, and measurement temperature: 25°C. Based on the measured value of Comparative Example 1, if the transmission loss was reduced, it was evaluated as ◯, and if the transmission loss was unchanged or increased, it was evaluated as ×.

[0194] [Table 2] [Explanation of symbols]

[0195] 2, 2a, 2b, 2c, 2d...insulating material layer, 4...plating seed layer, 6...conductor layer, 10...substrate, 20...conductor wiring, 30...insulating magnetic layer, 50, 52...laminated body, 100, 110...wiring board, H1, H2...openings.

Claims

1. A method for manufacturing a wiring board comprising: a substrate; a conductor wiring provided on the substrate; and an insulating magnetic layer that covers at least a part of the periphery of the conductor wiring and is made of an insulator containing a magnetic material, the method comprising the steps of: (I) forming an insulating material layer on the substrate; A step (II) of forming an opening in the insulating material layer, the opening being open on a side opposite to the substrate; A step (III) of forming the insulating magnetic layer on at least the inner side surface of the opening; A step (IV) of forming a conductor wiring on the insulating magnetic layer; A method for manufacturing a wiring board comprising the steps of:

2. The step (III) is a step of forming the insulating magnetic layer on an inner side surface of the opening and on a surface of the insulating material layer other than the opening, 2. The method for manufacturing a wiring board according to claim 1, wherein the step (IV) includes the steps of: preparing a laminate in which a conductor layer is formed on the insulating magnetic layer; and forming the conductor wiring by removing a portion of the laminate on a side opposite to the substrate.

3. 3. The method for manufacturing a wiring board according to claim 1, wherein the insulating magnetic layer has a coating thickness of 0.1 to 100 μm.

4. 4. The method for manufacturing a wiring board according to claim 1, wherein the magnetic material is a metal oxide or an amorphous metal.

5. 5. The method for manufacturing a wiring board according to claim 1, wherein the insulator has a relative magnetic permeability of 2 to 1000.

6. 6. The method for manufacturing a wiring board according to claim 1, wherein the insulator has a relative dielectric constant of 1 to 30.

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