TW202106503A - Magnetic film - Google Patents

Abstract

Provided are a magnetic film which is capable of, when the magnetic film has a resin composition layer that comprises a magnetic powder, suppressing the attachment of foreign substances to the resin composition layer, and a method for manufacturing the magnetic film. The magnetic film includes a support, a resin composition layer that is provided on the support and is formed from a resin composition, and a cover film layer that is connected to a surface of the resin composition layer opposite the support. The resin composition comprises a magnetic powder, and the cover film layer is a self-adhesive film.

Description

Magnetic film

The present invention relates to a resin composition layer containing magnetic powder and a magnetic film with a protective film layer.

Information terminal devices such as mobile phones and smart phones are equipped with many power inductors, inductors for high frequency bands, and inductors called common mode choke coils. In the past, independent inductance components were mounted on the circuit board. However, in recent years, the method of forming a coil by the conductor pattern of the circuit board to install the inductance inside the circuit board has been gradually implemented.

For example, Patent Document 1 discloses an inductance substrate that is embedded in a core substrate of the circuit board in order to reduce the thickness of the circuit board, and also discloses an inductance substrate in which an inductance is formed by a plurality of conductor patterns formed on an insulating layer. Also disclosed is an adhesive film, which can be used as a material for forming an insulating layer by including magnetic powder in the resin composition constituting the resin composition layer of the resin sheet with a support.

In order to meet the demand for further thinning and miniaturization of information terminal devices in recent years, and to further thin and miniaturize inductance elements, it is necessary to reduce the number of turns of the coil and reduce the cross-sectional area of the wiring that constitutes the coil. However, for the inductance formed by the conductive pattern on the magnetic layer formed by the adhesive magnetic film as described above, if the number of turns of the coil is simply reduced, and the cross-sectional area of the wiring constituting the coil is reduced, the inductance will be reduced. . On the other hand, as long as the permeability (μ') of the magnetic layer can be increased, the L value and Q value of the inductance element can be increased. Therefore, it is necessary to develop a magnetic thin film that can form a high permeability magnetic layer. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2012-186440 A

[The problem to be solved by the invention]

Incidentally, the adhesive film used for the insulating layer application of a printed circuit board is generally manufactured by coating a varnish of a resin composition on a support, and heating and drying the resin composition to form a resin composition layer. Here, a protective film layer may be provided on the resin composition layer on the surface of the resin composition layer on the opposite side to the support side in order to prevent the adhesion of foreign matter. The protective film mainly uses biaxially stretched polypropylene film (OPP film).

However, the inventors of the present invention found that in the magnetic film, if a protective film layer is provided on the resin composition layer containing magnetic powder, the protective film layer tends to be difficult to adhere to the resin composition layer. . In particular, the more the content of the magnetic powder in the resin composition is increased in order to achieve high magnetic permeability and the like, the tendency becomes more pronounced. In the adhesive film that has a resin composition layer containing inorganic fillers such as silicon dioxide and is used for the insulating layer of a printed circuit board, since the protective film layer is easily attached to the resin composition layer, the aforementioned problems will be caused by the use of The resin composition layer of the magnetic powder has caused new problems.

In the case where the protective film layer is not provided on the magnetic film, among single-piece products, the risk of foreign matter adhesion increases when the film is made into a single-piece form or when it is packaged. On the other hand, if it is a roll-shaped product, compared with a single sheet, the risk of adhesion of dirt can be reduced. However, even in this case, there is a risk of adhesion of foreign matter existing on the surface of the support when it is wound into a roll shape. In addition, even in a roll shape, when the magnetic film is slit and used, the risk of foreign matter adhesion increases.

The subject of the present invention is to provide a magnetic film, which can prevent foreign matter from adhering to the resin composition layer by providing a protective film layer on the resin composition layer containing magnetic powder; and a manufacturing method thereof. [Means used to solve the problem]

The inventors of the present invention conducted intensive studies in order to achieve the above-mentioned object, and as a result, found that even if the predetermined protective film layer is a resin composition layer containing magnetic powder, it is easy to stick, and completed the present invention.

That is, the present invention includes the following contents. [1]　A magnetic film, which has: Support body, and The resin composition layer provided on the support and formed of the resin composition, and The protective film layer bonded to the surface of the resin composition layer on the opposite side to the support side, and The resin composition contains magnetic powder, The protective film layer is a self-adhesive film. [2] "The magnetic film as in [1], wherein when the non-volatile content of the resin composition is 100% by mass, the content of the magnetic powder is 75% by mass or more and 98% by mass or less. [3] "The magnetic film as in [1] or [2], wherein the minimum melt viscosity of the resin composition layer is 50,000 poise or more and 50,000,000 poise. [4] "The magnetic film as in any one of [1] to [3], wherein the resin composition is a thermosetting resin composition. [5] "The magnetic film as in any one of [1] to [4], wherein the resin composition contains epoxy resin. [6] "The magnetic film as in any one of [1] to [5], wherein the resin composition contains at least any one of a hardening agent and a hardening accelerator. [7] "The magnetic film as in any one of [1] to [6], wherein the resin composition contains a thermoplastic resin. [8] "The magnetic film as in any one of [1] to [7], wherein the adhesion strength of the protective film layer to the resin composition layer is 0.1 gf/cm or more and 10 gf/cm or less. [9] "The magnetic thin film as in any one of [1] to [8], wherein the magnetic powder is at least one selected from iron oxide powder and iron alloy metal powder. [10]　 A method for manufacturing a magnetic film, which is the method for manufacturing a magnetic film as described in any one of [1] to [9], and includes: The step of coating a resin varnish containing a resin composition on the support to form a resin composition layer; and The step of laminating a protective film layer on the resin composition layer. [Effects of Invention]

According to the present invention, it is possible to provide a magnetic film capable of suppressing foreign matter from adhering to the resin composition layer even when it has a resin composition layer containing magnetic powder; and a manufacturing method thereof.

The following describes the embodiments of the present invention with reference to the drawings. In addition, FIG. 1 schematically shows the shape, size, and arrangement of the constituent elements to the extent that the present invention can be understood. The present invention is not limited by the following description, and each constituent element can be appropriately changed. In the drawings used in the following description, the same components are denoted by the same symbols, and repeated descriptions may be omitted. In addition, the configuration related to the embodiment of the present invention is not necessarily manufactured or used in accordance with the configuration illustrated in the figure.

[Magnetic Film] The magnetic film of the present invention has a resin composition layer provided on a support and formed of a resin composition; and a protective film layer bonded to the surface of the resin composition layer opposite to the support side, and the resin composition contains Magnetic powder, the protective film layer is a self-adhesive film. Between the support and the resin composition layer, one or more arbitrary layers may be provided.

Fig. 1 is a schematic cross-sectional view showing an example of the magnetic thin film of the present invention. In the magnetic film 1 shown in FIG. 1, a support 11, a resin composition layer 12, and a protective film layer 13 are laminated in this order. Hereinafter, each layer constituting the magnetic thin film of the present invention will be described in detail.

＜Support body＞ The magnetic film has a support. Examples of the support include films made of plastic materials, metal foils, and release paper, and films made of plastic materials and metal foils are preferred.

In the case of using a film formed of a plastic material as a support, the plastic material may include, for example, polyethylene terephthalate (hereinafter referred to as "PET"), polyethylene naphthalate (hereinafter referred to as "PET"). There may be polyester such as "PEN"), polycarbonate (hereinafter referred to as "PC"), acrylic acid such as polymethylmethacrylate (PMMA), cyclic polyolefin, three Acetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, polyimide, etc. In particular, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

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

When the support body and the resin composition layer are joined, the side where the support body and the resin composition layer are joined may be subjected to matte treatment or corona treatment.

In addition, when the support is joined to the resin composition layer, etc., a support with a mold release layer having a mold release layer on the side where the support and the resin composition layer are joined can also be used. The mold release agent used in the mold release layer of the support with the mold release layer includes, for example, one or more selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. Release agent. The support with a release layer can be a commercially available product. For example, it is a PET film with a release layer mainly composed of an alkyd resin-based release agent. Examples include "SK-1" and "AL- 5", "AL-7", "Lumirror T60" manufactured by Toray, "Purex" manufactured by Teijin, "Unipeel" manufactured by UNITIKA, etc.

The thickness of the support is not particularly limited, but the range of 5 μm to 75 μm is preferable, and the range of 10 μm to 60 μm is more preferable. In addition, in the case of using a support with a release layer, the total thickness of the support with a release layer is preferably in the above-mentioned range.

＜Resin composition layer＞ The magnetic film has a resin composition layer containing a resin composition. The resin composition layer is formed directly or indirectly on the support, and a protective film layer is provided on the surface opposite to the surface on the support side. The resin composition may contain magnetic powder, and the hardened product usually has sufficient mechanical strength and specific permeability. Therefore, the resin composition is preferably a thermosetting resin composition containing magnetic powder. The thermosetting resin composition includes, for example, a composition containing magnetic powder and thermosetting resin. As the thermosetting resin, conventionally known curable resins used when forming the magnetic layer of the inductor element can be used, and among them, epoxy resin is preferred. Therefore, in one embodiment, the resin composition contains (a) magnetic powder and (b) epoxy resin. The resin composition may further contain (c) a curing agent, (d) a curing accelerator, (e) a thermoplastic resin, (f) an inorganic filler other than the magnetic powder, and (g) other additives as necessary.

-(a) Magnetic powder- The resin composition contains (a) magnetic powder. When the inductor substrate contains a cured product of the resin composition layer, (a) the magnetic powder is preferably a soft magnetic powder. (a) Magnetic powders, such as soft magnetic powders, including pure iron powder; Mg-Zn-based ferrous iron, Fe-Mn-based ferrous iron, Mn-Zn-based ferrous iron, and Mn-Mg-based ferrous iron , Cu-Zn series fertilizer grain iron, Mg-Mn-Sr series fertilizer grain iron, Ni-Zn series fertilizer grain iron, Ba-Zn series fertilizer grain iron, Ba-Mg series fertilizer grain iron, Ba-Ni series fertilizer grain iron , Ba-Co series fertilizer grain iron, Ba-Ni-Co series fertilizer grain iron, Y series fertilizer grain iron, iron oxide powder (III), iron oxide powder such as ferroferric oxide; Fe-Si series alloy powder, Fe -Si-Al alloy powder, Fe-Cr alloy powder, Fe-Cr-Si alloy powder, Fe-Ni-Cr alloy powder, Fe-Cr-Al alloy powder, Fe-Ni alloy powder, Fe -Ni-Mo-based alloy powder, Fe-Ni-Mo-Cu-based alloy powder, Fe-Co-based alloy powder, or Fe-Ni-Co-based alloy powder and other ferroalloy metal powders; Co-based amorphous and other amorphous Alloy category.

In particular, (a) the magnetic powder is preferably at least one selected from iron oxide powder and iron alloy metal powder. The iron oxide powder preferably contains ferrite grains containing at least one selected from Ni, Cu, Mn, and Zn. In addition, the iron alloy metal powder preferably contains iron alloy metal powder containing at least one selected from Si, Cr, Al, Ni, and Co.

(a) As the magnetic powder, commercially available magnetic powder can be used. Specific examples of commercially available magnetic powders that can be used include "M05S" manufactured by Powdertech; "PST-S" manufactured by Sanyo Special Steel Co., Ltd.; "AW2-08" and "AW2-08PF20F manufactured by EPSON ATMIX. ", "AW2-08PF10F", "AW2-08PF3F", "Fe-3.5Si-4.5CrPF20F", "Fe-50NiPF20F", "Fe-80Ni-4MoPF20F"; "LD-M", " LD-MH", "KNI-106", "KNI-106GSM", "KNI-106GS", "KNI-109", "KNI-109GSM", "KNI-109GS"; "KNS- 415", "BSF-547", "BSF-029", "BSN-125", "BSN-125", "BSN-714", "BSN-828", "S-1281", "S-1641" , "S-1651", "S-1470", "S-1511", "S-2430"; "JR09P2" manufactured by Japan Heavy Chemical Industry Co., Ltd.; "Nanotek" manufactured by CIK NanoTek; manufactured by KINSEI MATEC "JEMK-S", "JEMK-H": "Yttrium iron oxide" manufactured by ALDRICH, etc. The magnetic powder may be used singly, or two or more of them may be used in combination.

(a) The magnetic powder is preferably spherical. The value (aspect ratio) obtained by dividing the length of the major axis of the magnetic powder by the length of the minor axis is preferably 2 or less, preferably 1.5 or less, and more preferably 1.2 or less. Generally speaking, among the magnetic powders, the non-spherical flat shape is easier to increase the specific permeability. However, in general, from the viewpoint of reducing the magnetic loss, it is particularly preferable to use spherical magnetic powder.

(a) The average particle diameter of the magnetic powder is preferably 0.01 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more from the viewpoint of increasing the specific permeability. In addition, it is preferably 8 μm or less, more preferably 5 μm or less, and more preferably 4 μm or less.

(a) The average particle size of the magnetic powder can be measured by the laser diffraction and scattering method based on the Mie scattering theory. Specifically, a laser diffraction scattering type particle size distribution measuring device can be used to produce the particle size distribution of the magnetic powder on a volume basis, and the median particle size can be determined as the average particle size for measurement. For the measurement sample, a sample prepared by dispersing magnetic powder in water by ultrasonic waves is suitable. The laser diffraction scattering type particle size distribution measuring device can be used "LA-500" manufactured by Horiba Manufacturing Co., Ltd., "SALD-2200" manufactured by Shimadzu Manufacturing Co., Ltd., etc.

(a) The content (vol%) of the magnetic powder, from the viewpoint of increasing the specific permeability and reducing the loss coefficient, when the non-volatile content in the resin composition is set to 100% by volume, it is preferably 10% by volume or more. It is preferably 20% by volume or more, and more preferably 30% by volume or more. In addition, it is preferably 85% by volume or less, preferably 80% by volume or less, and more preferably 75% by volume or less.

(a) The content (mass%) of the magnetic powder, from the viewpoint of increasing the specific permeability and reducing the loss coefficient, when the non-volatile content in the resin composition is set to 100% by mass, it is preferably 75% by mass or more. It is preferably 80% by mass or more, and more preferably 84% by mass or more. In addition, it is preferably 98% by mass or less, more preferably 96% by mass or less, and more preferably 95% by mass or less. In addition, in the present invention, the content of each component in the resin composition, unless otherwise specified, is a value when the non-volatile component in the resin composition is 100% by mass.

-(b)Epoxy resin- The resin composition contains epoxy resin as the component (b). (b) The epoxy resin can disperse and bond the (a) magnetic powder in the resin composition, and can form a magnetic layer with sufficient mechanical strength.

The epoxy resin includes, for example, glycerin type epoxy resin; bisphenol A type epoxy resin; bisphenol F type epoxy resin; bisphenol S type epoxy resin; bisphenol AF type epoxy resin; dicyclopentadiene Type epoxy resin; triphenol type epoxy resin; phenol novolak type epoxy resin; tertiary butyl-catechol type epoxy resin; naphthol novolak type epoxy resin, naphthalene type epoxy resin, naphthol type ring Epoxy resins with condensed ring structures such as oxy resins and anthracene type epoxy resins; glycidyl amine type epoxy resins; glycidyl ester type epoxy resins; cresol novolac type epoxy resins; biphenyl type epoxy resins Resin; linear aliphatic epoxy resin; epoxy resin with butadiene structure; alicyclic epoxy resin; heterocyclic epoxy resin; epoxy resin containing spiro ring; cyclohexanedimethanol epoxy resin Resin; Trimethylol type epoxy resin; Tetraphenylethane type epoxy resin, etc. The epoxy resin may be used alone or in combination of two or more kinds. The epoxy resin is preferably at least one selected from bisphenol A type epoxy resins and bisphenol F type epoxy resins.

The epoxy resin is preferably an epoxy resin having two or more epoxy groups in one molecule. In addition, the epoxy resin preferably has an aromatic structure, and when two or more types of epoxy resins are used, it is preferable that at least one of the epoxy resins has an aromatic structure. Aromatic structures are generally defined as chemical structures that are aromatic, including polycyclic aromatics and aromatic heterocycles. The ratio of epoxy resin having two or more epoxy groups in one molecule relative to 100% by mass of the non-volatile content of epoxy resin is preferably 50% by mass or more, preferably 60% by mass or more, and particularly preferably 70 Above mass%.

Epoxy resins are known to be liquid epoxy resins at a temperature of 25°C (hereinafter referred to as "liquid epoxy resins") and solid epoxy resins at a temperature of 25°C (hereinafter referred to as "liquid epoxy resins"). It is called "solid epoxy resin"). In the case of containing epoxy resin as component (b), the epoxy resin may contain only liquid epoxy resin, or only solid epoxy resin, or may contain liquid epoxy resin and solid epoxy resin The combination is preferably a combination containing a liquid epoxy resin and a solid epoxy resin from the viewpoint of improving the adhesion strength between the resin composition layer and the protective film layer.

Liquid epoxy resin, based on glycerin type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin Resin, glycidylamine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin with ester skeleton, cyclohexane dimethanol type epoxy resin and epoxy resin with butadiene structure are preferred Glycidylamine type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy citrus resin, bisphenol AF type epoxy resin and naphthalene type epoxy resin are preferred. Specific examples of liquid epoxy resins include "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resin) manufactured by DIC; "828US" and "jER828EL" (bisphenol A Type epoxy resin), "jER807" (bisphenol F type epoxy resin), "jER152" (phenol novolac type epoxy resin); "630" and "630LSD" manufactured by Mitsubishi Chemical Corporation, "ED" manufactured by ADEKA -523T” (ADEKA GLYCIROL), “EP-3980S” (glycidyl amine epoxy resin), “EP-4088S” (dicyclopentadiene epoxy resin); Nippon Steel "ZX1059" (mixed product of bisphenol A type epoxy resin and bisphenol F type epoxy resin), "EX-201" (cyclic aliphatic glycidyl ether), "ZX1658", "ZX1059" (mixed product of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Chemical & Material Co., Ltd. ZX1658GS" (liquid 1,4-glycidyl cyclohexane); "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX; "CELLOXIDE 2021P" manufactured by DAICEL (with ester skeleton The alicyclic epoxy resin), "PB-3600" (epoxy resin with butadiene structure) and so on. These may be used individually by 1 type, or may be used in combination of 2 or more types.

Solid epoxy resin, based on naphthalene type tetrafunctional epoxy resin, cresol novolac type epoxy citrus resin, dicyclopentadiene type epoxy resin, triphenol type epoxy resin, naphthol type epoxy resin, biphenyl Type epoxy resin, naphthyl ether type epoxy resin, anthracene type epoxy resin, bisphenol A type epoxy resin, tetraphenylethane type epoxy resin is preferred, naphthalene type tetrafunctional epoxy resin, naphthol type epoxy resin Oxygen resin and biphenyl type epoxy resin are preferable. Specific examples of solid epoxy resins include "HP4032H" (naphthalene type epoxy resin), "HP-4700", "HP-4710" (naphthalene type tetrafunctional epoxy resin), and "N- 690" (cresol novolac epoxy resin), "N-695" (cresol novolac epoxy resin), "HP-7200", "HP-7200HH", "HP-7200H" (dicyclopentadiene Type epoxy resin), "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthyl ether type epoxy resin); Japan-made "EPPN-502H" (triphenol type epoxy resin), "NC7000L" (naphthol novolac type epoxy resin), "NC3000H", "NC3000", "NC3000L", "NC3100" (biphenyl type Epoxy resin); "ESN475V" (naphthalene type epoxy resin) and "ESN485" (naphthol novolac epoxy resin) manufactured by Nippon Steel Chemical &Material; "YX4000H" and "YL6121" manufactured by Mitsubishi Chemical Corporation ( Biphenyl type epoxy resin), "YX4000HK" (bixylenol type epoxy resin), "YX8800" (anthracene type epoxy resin); "PG-100" and "CG-500" manufactured by Osaka Gas Chemical , "YL7760" (bisphenol AF type epoxy resin), "YL7800" (fluorene type epoxy resin), "jER1010" (solid bisphenol A type epoxy resin), "jER1031S" (four Phenylethane type epoxy resin) and so on. These may be used individually by 1 type, or may be used in combination of 2 or more types.

When a liquid epoxy resin and a solid epoxy resin are used together as component (b), the amount ratio of these resins (liquid epoxy resin: solid epoxy resin), in terms of mass ratio, is preferably 1: 0.1~1:4, preferably 1:0.3~1:3.5, more preferably 1:0.6~1:3.

The epoxy equivalent of the epoxy resin as the component (b) is preferably 50 g/eq. to 5000 g/eq., preferably 50 g/eq. to 3000 g/eq., more preferably 80 g/eq. to 2000 g/eq. ., more preferably 110g/eq.~1000g/eq. By setting in this range, the crosslinking density of the hardened material is sufficient, and a magnetic layer with a small surface roughness can be produced. In addition, epoxy equivalent can be measured based on JIS K7236, and is the mass of the resin containing 1 equivalent of epoxy groups.

The weight average molecular weight of the epoxy resin as the component (b) is preferably 100 to 5000, preferably 250 to 3000, and more preferably 400 to 1500. Here, the weight average molecular weight of the epoxy resin is a weight average molecular weight in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

(b) The content of epoxy resin, from the viewpoint of obtaining a magnetic layer exhibiting good mechanical strength, when the non-volatile content in the resin composition is set to 100% by mass, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, more preferably 1% by mass or more, preferably 20% by mass or less, preferably 15% by mass or less, more preferably 10% by mass or less.

-(c) Hardener- The resin composition may contain (c) a curing agent as an optional component. By using (c) curing agent, the curing of epoxy resin can be carried out efficiently, and the mechanical strength of the cured product can be improved. (c) curing agents include, for example, active ester curing agents, phenol curing agents, and naphthol curing agents. Hardener, benzoxazine hardener, cyanate ester hardener, carbodiimide hardener. From the viewpoint of the heat resistance and mechanical strength of the cured product of the resin composition, (c) the curing agent is preferably an active ester curing agent, a phenol curing agent, or a naphthol curing agent. (c) The hardener may be used singly, or two or more kinds may be used in combination.

As the active ester curing agent, a resin having one or more active ester groups in one molecule can be used. In particular, the active ester curing agent is preferably a resin having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxylamine esters, and heterocyclic hydroxy compound esters. The active ester curing agent is preferably obtained by a condensation reaction of a carboxylic acid compound and/or a thiocarboxylic acid compound and a hydroxyl compound and/or a thiol compound. In particular, from the viewpoint of improving heat resistance, an active ester curing agent obtained from a carboxylic acid compound and a hydroxy compound is preferred, and an active ester curing agent obtained from a carboxylic acid compound, a phenol compound and/or a naphthol compound is preferred For better.

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.

Phenol compounds or naphthol compounds, for example, hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, methylated bisphenol A, methylated bisphenol F, methylated bisphenol Phenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6 -Dihydroxy naphthalene, dihydroxy diphenyl ketone, trihydroxy diphenyl ketone, tetrahydroxy diphenyl ketone, phloroglucinol, benzene triol, dicyclopentadiene type diphenol compound, phenol phenolic aldehyde, etc. Here, the "dicyclopentadiene-type diphenol compound" refers to a diphenol compound obtained by condensing one molecule of dicyclopentadiene and two molecules of phenol.

Suitable specific examples of the active ester curing agent include an active ester curing agent containing a dicyclopentadiene type diphenol structure, an active ester curing agent containing a naphthalene structure, and an active ester curing agent containing a phenol phenolic compound. Ester hardener, active ester hardener containing phenol phenolic benzoyl compound. In particular, an active ester curing agent containing a naphthalene structure and an active ester curing agent containing a dicyclopentadiene type diphenol structure are preferable. "Dicyclopentadiene-type diphenol structure" means a divalent structural unit formed by phenylene-dicyclopentyl-phenylene.

Commercially available active ester hardeners. Examples of active ester hardeners containing dicyclopentadiene diphenol structure include "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T", and "HPC -8000H-65TM" and "EXB-8000L-65TM" (manufactured by DIC Corporation); examples of active ester hardeners containing naphthalene structure include "EXB9416-70BK" and "EXB-8150-65T" (manufactured by DIC Corporation); Examples of the active ester hardener of the phenol phenolic acetonitrile compound include "DC808" (manufactured by Mitsubishi Chemical Corporation); the active ester hardener of the phenol phenolic acetonitrile compound includes "YLH1026" (manufactured by Mitsubishi Chemical Corporation). ); The active ester hardener of the phenol phenolic acetonitrile may include "DC808" (manufactured by Mitsubishi Chemical Corporation); the active ester hardener of the phenol phenolic benzoyl compound may include "YLH1026" (Mitsubishi Chemical Corporation) "YLH1030" (manufactured by Mitsubishi Chemical Corporation), "YLH1048" (manufactured by Mitsubishi Chemical Corporation); etc.

Phenol-based curing agents and naphthol-based curing agents preferably have a phenolic structure from the viewpoint of heat resistance and water resistance. In addition, from the viewpoint of the adhesion of the conductor layer, a nitrogen-containing phenolic curing agent is preferred, and a phenolic curing agent containing a triazine skeleton is preferred.

Specific examples of phenol hardeners and naphthol hardeners include "MEH-7700", "MEH7810", and "MEH-7851" manufactured by Meiwa Chemical Co., Ltd., and "NHN" and "CBN manufactured by Nippon Kayaku Co., Ltd. ", "GPH", "SN170", "SN180", "SN190", "SN475", "SN485", "SN495", "SN-495V", "SN375", "SN395" manufactured by Nippon Steel Chemical & Material Co., Ltd. ", "TD-2090", "LA-7052", "LA-7054", "LA-1356", "LA-3018-50P", "EXB-9500", etc. manufactured by DIC.

Specific examples of benzoxazine-based hardeners include "JBZ-OD100" (benzoxazine ring equivalent 218), "JBZ-OP100D" (benzoxazine ring equivalent 218), and "ODA -BOZ" (benzoxazine ring equivalent 218); "Pd" (benzoxazine ring equivalent 217) and "Fa" (benzoxazine ring equivalent 217) manufactured by Shikoku Chemical Industry Co., Ltd.; Showa Polymer Corporation "HFB2006M" (benzoxazine ring equivalent 432) and so on.

The cyanate ester curing agent includes, for example, bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'- Methylene bis(2,6-dimethylphenyl cyanate), 4,4'-ethylene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis (4-cyanate ester) phenylpropane, 1,1-bis(4-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3 -Bis (4-cyanate phenyl-1-(methyl ethylene)) benzene, bis (4-cyanate phenyl) thioether and bis (4-cyanate phenyl) ether, etc. Difunctional cyanate ester resins; polyfunctional cyanate ester resins derived from phenol phenolic and cresol phenolic; these cyanate ester resins are partially triazine prepolymers; etc. Specific examples of cyanate ester curing agents include "PT30" and "PT60" (phenol novolac type polyfunctional cyanate resin) manufactured by Lonza Japan, "ULL-950S" (polyfunctional cyanate resin), "BA230", "BA230S75" (a prepolymer in which part or all of bisphenol A dicyanate is triazineized to become a trimer), etc.

Specific examples of carbodiimide hardeners include Carbodilite (registered trademark) V-03 (carbodiimide equivalent: 216) and V-05 (carbodiimide equivalent: 262) manufactured by Nisshinbo Chemical Co., Ltd. , V-07 (carbodiimide equivalent: 200); V-09 (carbodiimide equivalent: 200); Stabaxol (registered trademark) P (carbodiimide equivalent: 302) manufactured by Rhein Chemie .

In the case of containing epoxy resin and hardener, the ratio of the amount of epoxy resin to hardener is based on the ratio of [total number of epoxy groups in epoxy resin]: [total number of reactive groups in hardener], The range of 1:0.01~1:5 is preferred, 1:0.1~1:3 is preferred, and 1:0.5~1:2 is more preferred. Here, "the number of epoxy groups of the epoxy resin" refers to the value obtained by dividing the mass of the non-volatile components of the epoxy resin present in the resin composition by the epoxy equivalent. In addition, the "number of active groups of the curing agent" refers to the total value obtained by dividing the mass of the non-volatile components of the curing agent present in the resin composition by the equivalent of the active groups.

(c) The content of the hardener, from the viewpoint of obtaining a magnetic layer exhibiting good mechanical strength, when the non-volatile content in the resin composition is set to 100% by mass, it is preferably 0.1% by mass or more, more preferably 0.3 Mass% or more, more preferably 0.5 mass% or more. The upper limit is not particularly limited as long as the effects of the present invention can be exhibited, and it is preferably 5 mass% or less, preferably 3 mass% or less, and more preferably 2 mass% or less.

-(d) Hardening accelerator- The resin composition may further contain a hardening accelerator as the component (d) as an optional component. By using (d) the hardening accelerator, the hardening of the epoxy resin can be carried out efficiently, and the mechanical strength of the hardened product can be improved. (d) Hardening accelerators include, for example, amine hardening accelerators, imidazole hardening accelerators, phosphorus hardening accelerators, guanidine hardening accelerators, metal hardening accelerators, and the like. (d) The hardening accelerator is preferably an imidazole hardening accelerator. (d) The hardening accelerator may be used alone or in combination of two or more.

Amine-based hardening accelerators include, for example, trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6,- ginseng (dimethyl Aminomethyl)phenol, 1,8-diazabicyclo(5,4,0)-undecene, etc., 4-dimethylaminopyridine, 1,8-diazabicyclo(5,4, 0)-Undecene is preferred.

The imidazole-based hardening accelerators include, for example, 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-Dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1- Benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methyl Imidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolinium trimellitate, 1-cyanoethyl-2-phenylimidazolinium trimellitate Trisalt, 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 addition Product, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dimethylolimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2, 3-Dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolinium chloride, 2-methylimidazoline, 2 -Imidazole compounds such as phenylimidazoline and adducts of imidazole compounds and epoxy resins, preferably 2-ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole.

As the imidazole-based hardening accelerator, commercially available products can be used, and examples thereof include "2MZA-PW" and "2PHZ-PW" manufactured by Shikoku Chemical Co., Ltd., and "P200-H50" manufactured by Mitsubishi Chemical Corporation.

Phosphorus-based hardening accelerators include, for example, triphenyl phosphine, boric acid phosphonium compounds, tetraphenyl phosphonium tetraphenyl borate, n-butyl phosphonium tetraphenyl borate, tetrabutyl phosphonium decanoate, (4-methyl (Phenyl) triphenyl phosphonium thiocyanate, tetraphenyl phosphonium thiocyanate, butyl triphenyl phosphonium thiocyanate, etc., triphenyl phosphine, tetrabutyl phosphonium decanoate are good.

Guanidine-based hardening accelerators include, for example, dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, metformin Guanidine, 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-methyl biguanide, 1-ethyl biguanide, 1-n-butyl biguanide, 1-n-octadecyl biguanide, 1, 1-Dimethyl biguanide, 1,1-diethyl biguanide, 1-cyclohexyl biguanide, 1-allyl biguanide, 1-phenyl biguanide, 1-(o-tolyl) biguanide, etc., dicyandiamide , 1,5,7-triazabicyclo[4.4.0]dec-5-ene is preferred.

Examples of metal-based hardening accelerators include organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organic cobalt complexes such as cobalt acetone (II) and cobalt acetone (III), organic copper complexes such as copper acetone (II), and Organic zinc complexes such as zinc acetone (II), organic iron complexes such as iron acetone (III), organic nickel complexes such as nickel acetone (II), manganese acetone (II) ) And other organic manganese complexes. Examples of organic metal salts include zinc octoate, tin octoate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

(d) The content of the hardening accelerator, from the viewpoint of obtaining a magnetic layer exhibiting good mechanical strength, when the non-volatile content in the resin composition is 100% by mass, it is preferably 0.001% by mass or more, and more preferably 0.003 mass% or more, more preferably 0.005 mass% or more. The upper limit is preferably 1% by mass or less, preferably 0.1% by mass or less, and more preferably 0.05% by mass or less.

In the resin composition, from the viewpoint of effectively curing the epoxy resin and improving the mechanical strength of the cured product, it is preferable to contain at least one of (c) a curing agent and (d) a curing accelerator. Both (c) a hardening agent and (d) a hardening accelerator are preferable.

-(e) Thermoplastic resin- The resin composition may contain (e) a thermoplastic resin as an optional component. By using (e) the thermoplastic resin, the stress of the resin composition layer can be relieved.

(e) Thermoplastic resins, such as phenoxy resins, acrylic resins, polycarbonate resins, polyvinyl acetal resins, polyolefin resins, polyimide resins, polyimide resins, and polyether amide resins. Amine resin, polyether resin, polyether resin, polyphenylene ether resin, polyether ether ketone resin, polyester resin, etc. In particular, from the viewpoint of remarkably obtaining the desired effect of the present invention, at least one selected from the group consisting of acrylic resin, polyvinyl acetal resin, and phenoxy resin is preferred, and phenoxy resin is preferred. In addition, (e) the thermoplastic resin may be used alone or in combination of two or more kinds.

As the polyimide resin, a resin having an amide structure can be used. Such resins include, for example, linear polyimides obtained by reacting difunctional hydroxyl-terminated polybutadiene, diisocyanate compounds, and tetrabasic acid anhydrides (polyimides described in JP 2006-37083 A). Amine), a polyimide containing a polysiloxane skeleton (a polyimide described in JP 2002-12667 A, JP 2000-319386 A, etc.) and other modified polyimides.

A commercially available product can be used for the polyimide resin. Commercially available products include "RIKACOAT SN20" and "RIKACOAT PN20" manufactured by Nippon Rika Corporation.

As the polycarbonate resin, a resin having a carbonate structure can be used. Such resins include hydroxyl-containing carbonate resins, phenolic hydroxyl-containing carbonate resins, carboxyl-containing carbonate resins, acid anhydride group-containing carbonate resins, isocyanate group-containing carbonate resins, and urethane-containing resins. -Based carbonate resins, etc.

Commercially available carbonate resins can be used. Commercially available products include "FPC0220" manufactured by Mitsubishi Gas Chemical Corporation, "T6002" and "T6001" (polycarbonate diol) manufactured by Asahi Kasei Chemicals. "C-1090", "C-2090", "C-3090" (polycarbonate diol), etc. manufactured by Kuraray.

Examples of phenoxy resins include those having a skeleton selected from the group consisting of bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenol acetophenone skeleton, phenolic skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, A phenoxy resin having one or more skeletons from the group consisting of a norbornene skeleton, a naphthalene skeleton, an anthracene skeleton, an adamantane skeleton, a terpene skeleton, and a trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group and an epoxy group.

Specific examples of phenoxy resins include "1256" and "4250" manufactured by Mitsubishi Chemical Corporation (any of them are phenoxy resins containing a bisphenol A skeleton); and "YX8100" manufactured by Mitsubishi Chemical Corporation (containing Bisphenol S skeleton phenoxy resin); “YX6954” (phenoxy resin containing bisphenol acetophenone skeleton) produced by Mitsubishi Chemical Corporation; “FX280” and “FX293” produced by Nippon Steel Chemical &Material; "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290", "YL7553BH30" and "YL7482" manufactured by Mitsubishi Chemical Corporation; etc.

As the acrylic resin, from the viewpoint of remarkably obtaining the effects of the present invention, a functional group-containing acrylic resin is preferred, and an epoxy group-containing acrylic resin having a glass transition temperature of 25°C or less is preferred. Examples of the functional group of the functional group-containing acrylic resin include a phenolic hydroxyl group and an epoxy group.

The number average molecular weight (Mn) of the acrylic resin containing functional groups is preferably 10,000 to 1,000,000, preferably 30,000 to 900,000.

The functional group contains the equivalent of the functional group of the acrylic resin, preferably 1,000 to 50,000, preferably 2,500 to 30,000.

An acrylic resin with a glass transition temperature of 25°C or less and containing an epoxy group is preferably an acrylate copolymer resin with a glass transition temperature of 25°C or less and containing an epoxy group. Specific examples include "Nagase Chemtex Co., Ltd." SG-80H" (epoxy-containing acrylate copolymer resin (number average molecular weight Mn: 350,000 g/mol, epoxy value 0.07 eq/kg, glass transition temperature 11°C)), "SG-P3" manufactured by Nagase Chemtex (Epoxy group-containing acrylate copolymer resin (number average molecular weight Mn: 850,000 g/mol, epoxy value 0.21 eq/kg, glass transition temperature 12°C)).

Examples of the polyvinyl acetal resin include polyvinyl formaldehyde resin and polyvinyl butyral resin, and polyvinyl butyral resin is preferred. Specific examples of polyvinyl acetal resins include electrochemical Butyral "4000-2", "5000-A", "6000-C", "6000-EP" manufactured by Denka Corporation, and S-LEC manufactured by Sekisui Chemical Industry Co., Ltd. BH series, BX series (such as BX-5Z), KS series (such as KS-1), BL series, BM series; etc.

Specific examples of polyimide resins include "VYLOMAX HR11NN" and "VYLOMAX HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyimide resins include denatured polyimide imides such as "KS9100" and "KS9300" (polysiloxane skeleton containing polyimide imide) manufactured by Hitachi Chemical Co., Ltd. .

Specific examples of the polyether sulfide resin include "PES5003P" manufactured by Sumitomo Chemical Co., Ltd. and the like.

Specific examples of the polyphenylene ether resin include oligophenylene ether and styrene resin "OPE-2St 1200" manufactured by Mitsubishi Gas Chemical Corporation.

Specific examples of the polymer resin include polymer "P1700" and "P3500" manufactured by Solvay specialty polymers.

(e) The weight average molecular weight (Mw) of the thermoplastic resin is preferably 8,000 or more, more preferably 10,000 or more, particularly preferably 20,000 or more, preferably 1,000,000 or less, from the viewpoint of remarkably obtaining the desired effect of the present invention. Preferably it is 750,000 or less, particularly preferably 500,000 or less.

(e) The content of the thermoplastic resin, from the viewpoint of remarkably obtaining the desired effect of the present invention, when the non-volatile content in the resin composition is set to 100% by mass, it is preferably 1% by mass or more, preferably 2% by mass % Or more, more preferably 3% by mass or more, preferably 25% by mass or less, preferably 20% by mass or less, more preferably 15% by mass or less.

-(f) Inorganic fillers other than magnetic powder- The resin composition may contain (f) inorganic fillers other than the magnetic powder (hereinafter sometimes referred to simply as "(f) inorganic fillers") as optional components. By including (f) an inorganic filler other than the magnetic powder in the resin composition, it is possible to impart other functions of the inorganic filler such as insulation improvement to the resin composition layer.

(f) The material of the inorganic filler is an inorganic compound, such as silica, alumina, glass, vermilionite, silica, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, Alluvium, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate , Bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate, etc., are not particularly limited. Among these, silicon dioxide is particularly suitable. Examples of silicon dioxide include amorphous silicon dioxide, fused silicon dioxide, crystalline silicon dioxide, synthetic silicon dioxide, and hollow silicon dioxide. In addition, the silica is preferably spherical silica. (f) A component may be used individually by 1 type, or may be used in combination of 2 or more types.

(f) Commercial products of inorganic fillers include, for example, "UFP-30" manufactured by Denka; "SP60-05" and "SP507-05" manufactured by Nippon Steel Chemical &Material; and "YC100C manufactured by Admatechs" ”, “YA050C”, “YA050C-MJE”, “YA010C”; “Sirfil NSS-3N”, “Sirfil NSS4N”, “Sirfil NSS-5N” manufactured by Tokuyama Corporation; “SC2500SQ”, “SO- C4", "SO-C2", "SO-C1"; etc.

(f) The average particle diameter of the inorganic filler is preferably 0.01 μm or more, more preferably 0.05 μm or more, more preferably 0.1 μm or more, and 0.3 μm or more from the viewpoint of remarkably obtaining the desired effect of the present invention. In addition, it is preferably 5 μm or less, more preferably 2.5 μm or less, more preferably 1.5 μm or less, and 1 μm or less. The average particle diameter of the inorganic filler can be measured by the same method as (a) the method for measuring the average particle diameter of the magnetic powder.

(f) The inorganic filler is preferably treated with a surface treatment agent from the viewpoint of improving moisture resistance and dispersibility. Surface treatment agents include, for example, fluorine-containing silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, titanium Acid ester coupling agent, etc. In addition, the surface treatment agent may be used alone in one kind, or two or more kinds may be used in any combination.

Commercial products of surface treatment agents include, for example, "KBM403" (3-glycidoxypropyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., and "KBM803" (3-mercaptopropane) manufactured by Shin-Etsu Chemical Co., Ltd. Trimethoxysilane), "KBE903" (3-aminopropyltriethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., and "KBM573" (N-phenyl-3-aminopropyl) manufactured by Shin-Etsu Chemical Co., Ltd. Trimethoxysilane), "SZ-31" (hexamethyldisilazane) manufactured by Shin-Etsu Chemical Co., Ltd., "KBM103" (phenyltrimethoxysilane) manufactured by Shin-Etsu Chemical Co., Ltd., Shin-Etsu Chemical Co., Ltd. "KBM-4803" (long-chain epoxy silane coupling agent) manufactured by Shin-Etsu Chemical Co., Ltd. (3,3,3-trifluoropropyltrimethoxysilane), etc.

The degree of surface treatment with the surface treatment agent, from the viewpoint of improving the dispersibility of the inorganic filler, it is better to perform the surface treatment with 0.2 to 5 parts by mass of the surface treatment agent relative to 100 parts by mass of the inorganic filler , Or suitable for surface treatment with 0.2 parts by mass to 3 parts by mass, or suitable for surface treatment with 0.3 parts by mass to 2 parts by mass.

The degree of surface treatment with a surface treatment agent can be evaluated by the amount of carbon per unit surface area of the inorganic filler. The amount of carbon per unit surface area of the inorganic filler, from the viewpoint of improving the dispersibility of the inorganic filler, is preferably 0.02 mg/m ² or more, preferably 0.1 mg/m ² or more, and 0.2 mg/m ² or more Better. On the other hand, from the standpoint of suppressing the melt viscosity of the resin varnish and the melt viscosity in the form of a sheet, 1 mg/m ² or less is preferable, 0.8 mg/m ² or less is more preferable, and 0.5 mg/m ² The following is better.

The amount of carbon per unit surface area of the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (for example, methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent was added to the inorganic filler surface-treated with a surface treatment agent, and ultrasonic cleaning was performed at 25°C for 5 minutes. The supernatant liquid is removed, the solid content is dried, and then the carbon content per unit surface area of the inorganic filler can be measured using a carbon analyzer. The carbon analyzer can use "EMIA-320V" manufactured by Horiba Manufacturing Co., Ltd., etc.

(f) The content (mass%) of the inorganic filler, when the non-volatile content in the resin composition is 100% by mass, it is preferably 1% by mass or more, preferably 1.5% by mass or more, more preferably 2% by mass the above. In addition, it is preferably 10% by mass or less, more preferably 8% by mass or less, and more preferably 5% by mass or less.

(f) The content (vol%) of the inorganic filler is preferably 1 vol% or more, preferably 3 vol% or more, more preferably 5 vol% or more. In addition, the upper limit is preferably 20% by volume or less, preferably 15% by volume or less, and more preferably 10% by volume or less.

-(g) Other additives- The resin composition may further contain (g) other additives as necessary. Examples of the additives include resin additives such as flame retardants, tackifiers, defoamers, levelers, adhesion imparting agents, and coloring agents.

The resin composition can be produced by, for example, a method of stirring the ingredients of the formula using a stirring device such as a three-roller, a rotary stirrer, or a high-speed rotary stirrer. The resin composition may be defoamed after manufacture. Examples include static degassing, centrifugal separation degassing, vacuum degassing, stirring degassing, and a combination of these methods for degassing.

As described above, in order to increase the specific permeability of the magnetic layer formed of the magnetic thin film, it is conceivable to increase the content of the magnetic powder contained in the resin composition layer of the magnetic thin film. If the content of the magnetic powder increases, the minimum melt viscosity of the resin composition layer tends to increase. In addition, when the magnetic layer is formed by a magnetic thin film, if the magnetic layer is formed by hot pressing, the density of the magnetic powder in the magnetic layer can be made higher, and therefore the specific permeability of the magnetic layer can be made higher. Generally speaking, the adhesive film used to form the insulating layer of the circuit board can be laminated by a vacuum laminator and then thermally cured to form the insulating layer. Therefore, the minimum melt viscosity is set to be relatively low. The minimum melt viscosity of the resin composition layer in the magnetic film of the invention is preferably set to be relatively high so as to be suitable for forming the magnetic layer by hot pressing. The lowest melt viscosity of the resin composition layer, from the above viewpoint, is preferably 50,000 poise or more, preferably 100,000 poise or more, more preferably 500,000 poise or more, preferably 50,000,000 poise or less, preferably 30,000,000 poise or less, more preferably It is less than 10,000,000 poise. The lowest melt viscosity of the resin composition layer can be measured by the method described in the following Examples.

From the viewpoint of thinning, the thickness of the resin composition layer is preferably 250 μm or less, preferably 200 μm or less, and more preferably 150 μm or less. The lower limit of the thickness of the resin composition layer is not particularly limited, and it can usually be set to 5 μm or more.

＜Protective film layer＞ The magnetic thin film has a protective film layer, and the protective film layer is provided on the resin composition layer. The inventors of the present invention found that, as mentioned above, the protective film layer tends to be difficult to adhere to the resin composition layer containing the magnetic powder, and even found that the higher the content of the magnetic powder, the harder the protective film layer adheres to. In the resin composition layer. It has also been found that when the minimum melt viscosity of the resin composition layer is set in a high range as described above to be suitable for forming a magnetic layer by hot pressing, it is more difficult for the protective film layer to adhere to the resin composition layer. In the present invention, by using a self-adhesive film as the protective film layer, even in such a case, the protective film layer can be provided on the resin composition layer. This can prevent foreign matter from adhering to the resin composition layer. In addition, if a magnetic film without a protective film layer is used, there will be a problem of foreign matter adhering to the surface of the resin composition layer. In addition, when the magnetic film is slit, the resin composition layer is likely to be cracked or chipped at the end of the film. tendency. According to the present invention, the protective film layer can be provided on the resin composition layer containing the magnetic powder. As a result, the adhesion of foreign matter on the resin composition layer and the occurrence of cracks or defects of the resin composition layer during slitting can be suppressed.

As mentioned above, the protective film layer is a self-adhesive film. The term "self-adhesive film" refers to a film having an adhesive surface formed by co-extruding a base resin and an adhesive resin, and it has adhesive strength even if no adhesive is applied.

The adhesive force of the self-adhesive film at 23°C for a glass slide is preferably 0.1gf/cm or more, preferably 0.2gf/cm or more, more preferably 0.5gf/cm or more, preferably 20gf/ cm or less, preferably 15 gf/cm or less, more preferably 10 gf/cm or less. The adhesive force of the self-adhesive film can be measured by the method described in the following Examples.

Examples of the adhesive resin include ethylene/vinyl acetate copolymer; polyolefin-based resins such as linear low-density polyethylene; styrene-based elastomers.

Examples of the base resin include polyethylene and polypropylene.

Commercially available products can be used for the protective film layer. Examples of commercially available protective films that can be used include "R025" and "R033KS" manufactured by Toray Film Processing Co., Ltd.; "FSA-300M" and "FSA-150M" manufactured by Futamura Chemical Co., Ltd.; and "FSA-150M" manufactured by Toyobo Co., Ltd. MS300".

The thickness of the protective film layer is preferably 100 μm or less, preferably 80 μm or less, and more preferably 60 μm or less. The lower limit is preferably 10 μm or more, preferably 15 μm or more, and more preferably 20 μm or more.

Films with adhesive surfaces, as well as adhesive-coated films formed by applying adhesive on the resin layer of the base material. However, when the protective film layer is peeled off, the adhesive remains on the resin composition layer, and the magnetic layer From the viewpoint of the decrease in adhesion to other layers or the difficulty in achieving high magnetic permeability, it is not suitable for the protective film layer of the present invention.

[Manufacturing method of magnetic film] The magnetic film of the present invention has, as described above, a support, a resin composition layer provided on the support and containing a resin composition, and a protective film layer provided on the resin composition layer. The manufacturing method of the magnetic film includes: (1) The step of coating a resin varnish on the support to form a resin composition layer; and (2) A step of laminating a protective film layer on the resin composition layer. The following describes each step.

<Step (1)> Step (1) is a step of coating a resin varnish on a support to form a resin composition layer, and by this step, a resin composition layer is formed on the support. In detail, step (1) is to prepare a resin varnish containing a resin composition in an organic solvent, apply the resin varnish on a support, and further dry it to form a resin composition layer.

The resin varnish is made by dissolving or dispersing a resin composition in an organic solvent. The resin composition is as previously described.

Organic solvents include ketone solvents such as acetone, methyl ethyl ketone (MEK) and cyclohexanone; ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol Acetate solvents such as acetate; carbitol solvents such as cellosolve and butyl carbitol; aromatic hydrocarbon solvents such as toluene and xylene; dimethylformamide, dimethylacetamide (DMAc) ) And N-methylpyrrolidone and other amide-based solvents. An organic solvent can be used individually by 1 type or in combination of 2 or more types.

The coating of the resin varnish can be carried out by a method capable of forming a coating film with a uniform thickness. For the coating method of the resin varnish, a coating device such as a die coater, a comma blade coater, a gravure coater, and a bar coater can be used to coat the resin varnish on the support. After coating the resin varnish on the support, the resin varnish is dried to form a resin composition layer.

Drying can be performed by a well-known method such as heating and hot air blowing. The drying conditions are not particularly limited, and it is preferable to dry until the organic solvent content in the resin composition layer becomes 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, or even 1% by mass or less.

Drying conditions vary according to the boiling point of the organic solvent in the resin varnish. For example, in the case of using a resin varnish containing 30% to 60% by mass of organic solvent, it can be dried at 50°C to 150°C for 3 minutes ~10 minutes to form the resin composition layer.

<Step (2)> Step (2) is a step of laminating a protective film on the resin composition layer, and by this step, a protective film layer is formed on the resin composition layer. In step (2), in detail, after the resin composition layer is formed, a protective film is further laminated on the side of the resin composition layer that is not bonded to the support (that is, the surface opposite to the support side).

For the bonding of the resin composition layer and the protective film, for example, the protective film is laminated on the resin composition layer by roll pressure or spray pressure, and the protective film is laminated on the resin composition layer.

The lamination treatment can be carried out under heating conditions. The heating temperature is preferably 30°C or higher, preferably 40°C or higher, more preferably 50°C or higher, preferably 150°C or lower, preferably 120°C or lower, and more preferably 100°C or lower.

The crimping pressure and crimping time of the lamination process are not particularly limited as long as the desired adhesive strength can be obtained, and they may be appropriately determined. For example, the crimping pressure is set in ^{the range of 0.1kgf/cm 2} ~18kgf/cm ² (0.0098MPa~1.77MPa), and the crimping time can be set in the range of 5 seconds to 400 seconds. The lamination treatment can be performed under reduced pressure conditions (for example, 26.7 hPa or less).

The lamination process can be performed by a commercially available vacuum laminator. Examples of commercially available vacuum laminators include vacuum pressure laminators manufactured by Meike Manufacturing Co., Ltd., vacuum laminators manufactured by Nikko-Materials, and the like.

＜Physical properties of magnetic film, etc.＞ The adhesive strength between the resin composition layer and the protective film layer is preferably 0.1 gf/cm or more, preferably 0.2 gf/cm or more, more preferably 0.3 gf/cm from the viewpoint of remarkably obtaining the effect of the present invention. cm above. The upper limit of the aforementioned adhesion strength is preferably 10 gf/cm or less, more preferably 8 gf/cm or less, and more preferably 6 gf/cm or less from the viewpoint of suppressing resin peeling when the protective film layer is peeled off. The adhesion strength is measured under the conditions of room temperature (23°C), and can be measured by the method described in the following Examples.

[Method of manufacturing magnetic layer] When the magnetic thin film of the present invention is used to manufacture a magnetic layer of an inductance element or the like, the magnetic layer can be manufactured by, for example, a method including the following steps (A) and (B). (A) The step of peeling off the protective film layer of the magnetic thin film; and (B) The step of laminating the magnetic thin film on the inner substrate, and joining the resin composition layer and the inner substrate to form a magnetic layer.

<Step (A)> Step (A) is a step of peeling off the protective film layer of the magnetic thin film. When step (A) is performed, a step of preparing a magnetic thin film may also be included. The magnetic film is as described above.

The method of peeling the protective film layer can be performed by the same method as the method of peeling the protective film layer on the adhesive film used for insulation and having a resin composition layer containing no magnetic powder. Peeling can be done manually or mechanically. When the magnetic film is in the form of a roll, the magnetic film can be transported while peeling the protective film layer, and when the magnetic film is a single piece, the protective film layer can be peeled using a peeling device or the like that peels the protective film layer.

<Step (B)> Step (B) is a step of laminating the magnetic thin film on the inner substrate, and joining the resin composition layer and the inner substrate to form a magnetic layer. In one embodiment of step (B), the magnetic thin film and the inner substrate are hot pressed, the resin composition layer and the inner substrate are joined, and the resin composition layer is thermally cured to form the magnetic layer.

The heating temperature of the hot pressing is preferably 130°C or higher, preferably 150°C or higher, and preferably 250°C or lower, preferably 200°C or lower.

The pressing time of the hot pressing is preferably 1 minute or more, preferably 2 minutes or more, in addition, it is preferably 24 hours or less, and preferably 2 hours or less.

The pressure of the hot pressing is preferably 0.1 MPa or more, preferably 1 MPa or more, more preferably 10 MPa or more, and more preferably 200 MPa or less, preferably 100 MPa or less.

After the magnetic layer is formed, the support is usually peeled off in the same way as the protective film layer. The magnetic thin film of the present invention is suitable for forming the magnetic layer of an inductor substrate. Such an inductor substrate can be used as a circuit board for mounting electronic components such as semiconductor chips, or can be used as a (multilayer) printed circuit board with the circuit board as an inner substrate. In addition, it can also be used as a chip inductor component in which the circuit board is singulated, or as a printed circuit board on which the chip inductor component is mounted on the surface.

In addition, various types of semiconductor devices can be manufactured using this circuit board. The semiconductor device containing the circuit board is suitable for use in electronic products (such as computers, mobile phones, digital cameras and televisions, etc.) and vehicles (such as locomotives, automobiles, trains, ships and airplanes, etc.). [Example]

The present invention will be explained more specifically in the following examples, but the present invention is not limited by these examples. In addition, in the following description, the "parts" and "%" indicating the content mean "parts by mass" and "% by mass", unless otherwise specified.

<Preparation of resin composition 1> 14 parts by mass of "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd.) and "HP-4700" (naphthalene type tetrafunctional epoxy resin, DIC Corporation) 14 parts by mass, "YX7553" (phenoxy resin, non-volatile content 30% by mass, manufactured by Mitsubishi Chemical Corporation) 35 parts by mass, "KS-1" (polyvinyl acetal resin, manufactured by Sekisui Chemical Industry Co., Ltd.) ) 23 parts by mass, heated and dissolved in 10 parts by mass of MEK, 10 parts by mass of cyclohexanone, 30 parts by mass of ethanol, and 30 parts by mass of toluene. Mix 28 parts by mass of "LA-7054" (triazine skeleton containing phenolic hardener, 60% by mass of non-volatile content, manufactured by DIC), and 0.1 mass of "2E4MZ" (hardening accelerator, manufactured by Shikoku Kasei Kogyo Co., Ltd.) Parts, 1010 parts by mass of "AW2-08PF3F" (magnetic powder, Fe-Cr-Si alloy (amorphous), average particle size 3.0μm, manufactured by EPSON ATMIX), and uniformly dispersed with a high-speed rotating stirrer to prepare Resin composition 1.

<Preparation of resin composition 2> In the resin composition 1, an inorganic filler ("SO-C2" (silica dioxide, average particle size 0.5μm, made by Admatechs) and "KBM-573" (aminosilane coupling agent, Shin-Etsu Chemical Co., Ltd.) was added to the resin composition 1. Industrial Co.) 35 parts by mass of treated silicon dioxide. Except for the above matters, a resin composition 2 was prepared in the same manner as the resin composition 1.

<Preparation of resin composition 3> 7 parts by mass of "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd.), "HP-4700" (naphthalene type tetrafunctional epoxy resin, DIC Company make) 7 parts by mass and 135 parts by mass of "YX7553" (phenoxy resin, 30% by mass of non-volatile content, manufactured by Mitsubishi Chemical Corporation) are stirred and heated to dissolve. Mix 14 parts by mass of "LA-7054" (triazine skeleton containing phenolic hardener, 60% by mass of non-volatile content, manufactured by DIC), and 0.1 mass of "2E4MZ" (hardening accelerator, manufactured by Shikoku Kasei Kogyo Co., Ltd.) Parts, "AW2-08PF3F" (magnetic powder, Fe-Cr-Si alloy (amorphous), average particle size 3.0μm, manufactured by EPSON ATMIX) 850 parts by mass, and uniformly dispersed with a high-speed rotating stirrer to prepare出resin composition 3.

<Preparation of resin composition 4> In the resin composition 3, 850 parts by mass of "AW2-08PF3F" (magnetic powder, Fe-Cr-Si alloy (amorphous), average particle size 3.0μm, manufactured by EPSON ATMIX) was changed to "M05S" (Magnetic powder, Fe-Mn-based fat iron, average particle size 3.0 μm, manufactured by Powdertech) 600 parts by mass. Except for the above matters, the resin composition 4 was prepared in the same manner as the resin composition 3.

<Preparation of resin composition 5> In resin composition 3, 850 parts by mass of "AW2-08PF3F" (magnetic powder, Fe-Cr-Si alloy (amorphous), average particle size 3.0μm, manufactured by EPSON ATMIX) was changed to "PST- S" (magnetic powder, Fe-Si-Al alloy, average particle size 25 μm, manufactured by Sanyo Special Steel Co., Ltd.) 850 parts by mass. Except for the above matters, the resin composition 5 was prepared in the same manner as the resin composition 3.

<Example 1: Preparation of magnetic film 1> A polyethylene terephthalate (hereinafter referred to as "PET") film (thickness: 38 μm) was prepared as a support. The resin composition 1 was uniformly coated on the PET film with a die coater so that the thickness of the dried resin composition layer was 100 μm, and dried at 65°C to 120°C for 8 minutes to make the resin composition layer remain The amount of solvent was 0.9% by mass. Next, a protective film "R205" (a self-adhesive film, manufactured by Toray Film Processing Co., Ltd., thickness 40 μm) was laminated on the surface of the resin composition layer at 60° C. to obtain a magnetic film 1.

<Example 2: Production of Magnetic Film 2> In Example 1, the protective film "R205" (self-adhesive film, manufactured by Toray Film Processing Co., Ltd., thickness 40μm) was changed to protective film "R033KS" (self-adhesive film, manufactured by Toray Film Processing Co., Ltd., thickness 45μm). Except for the above matters, a magnetic thin film 2 was produced in the same manner as in Example 1.

<Example 3: Production of Magnetic Film 3> In Example 1, the protective film "R205" (self-adhesive film, manufactured by Toray Film Processing Co., Ltd., thickness 40μm) was changed to protective film "FSA-300M" (self-adhesive film, manufactured by Futamura Chemical Co., Ltd., thickness 30μm). Except for the above matters, a magnetic thin film 3 was produced in the same manner as in Example 1.

<Example 4: Production of Magnetic Film 4> In Example 1, the protective film "R205" (self-adhesive film, manufactured by Toray Film Processing Co., Ltd., thickness 40μm) was changed to protective film "FSA-150M" (self-adhesive film, manufactured by Futamura Chemical Co., Ltd., thickness 30μm). Except for the above matters, the magnetic thin film 4 was produced in the same manner as in Example 1.

<Example 5: Production of Magnetic Film 5> In Example 1, the protective film "R205" (self-adhesive film, manufactured by Toray Film Processing Co., Ltd., thickness 40 μm) was changed to the protective film "MS300" (self-adhesive film, manufactured by Toyobo Co., Ltd., thickness 40 μm). Except for the above matters, a magnetic thin film 5 was produced in the same manner as in Example 1.

<Example 6: Production of Magnetic Film 6> The resin composition 2 was uniformly coated on the PET film with a die coater to make the thickness of the dried resin composition layer 100μm, and dried at 65°C to 120°C for 8 minutes to make the residual solvent in the resin composition layer The amount becomes 0.8% by mass. Next, a protective film "R033KS" (self-adhesive film, manufactured by Toray Film Processing Co., Ltd., thickness 45 μm) was laminated on the surface of the resin composition layer at 60° C. to obtain a magnetic film 6.

<Example 7: Preparation of Magnetic Film 7> In Example 6, the drying time was changed from 8 minutes to 10 minutes, and the amount of residual solvent in the resin composition layer was changed from 0.8% by mass to 0.5% by mass. Except for the above matters, a magnetic thin film 7 was produced in the same manner as in Example 6.

<Example 8: Preparation of Magnetic Film 8> In Example 6, the protective film "R033KS" (self-adhesive film, manufactured by Toray Film Processing Co., Ltd., thickness 45μm) was changed to protective film "FSA-150M" (self-adhesive film, manufactured by Futamura Chemical Co., Ltd., thickness 30μm). Except for the above matters, a magnetic thin film 8 was produced in the same manner as in Example 6.

<Example 9: Preparation of Magnetic Film 9> The resin composition 3 was uniformly coated on the PET film with a die coater so that the thickness of the dried resin composition layer was 100 μm, and dried at 65°C to 120°C for 8 minutes to make the resin composition layer remain The amount of solvent becomes about 1.3% by mass. Next, a protective film "FSA-150M" (a self-adhesive film, manufactured by Futamura Chemical Co., Ltd., thickness 30um) was laminated on the surface of the resin composition layer at 60°C to obtain a magnetic film 9.

<Example 10: Preparation of Magnetic Film 10> The resin composition 4 was uniformly coated on the PET film with a die coater so that the thickness of the resin composition layer after drying became 100 μm, and dried at 65°C to 120°C for 8 minutes to make the resin composition layer remain The amount of solvent becomes about 1.9% by mass. Next, a protective film "FSA-150M" (a self-adhesive film, manufactured by Futamura Chemical Co., Ltd., thickness 30 μm) was laminated on the surface of the resin composition layer at 60° C. to obtain a magnetic film 10.

<Example 11: Preparation of Magnetic Film 11> The resin composition 5 was uniformly coated on the PET film with a die coater, and the thickness of the dried resin composition layer was 100 μm, and dried at 65°C to 120°C for 8 minutes to make the resin composition layer The amount of residual solvent is about 1.2% by mass. Next, a protective film "FSA-150M" (self-adhesive film, manufactured by Futamura Chemical Co., Ltd., thickness 30 μm) was laminated on the surface of the resin composition layer at 60° C. to obtain a magnetic film 11.

<Comparative Example 1: Production of Magnetic Film 12> In Example 1, the protective film "R205" (self-adhesive film, manufactured by Toray Film Processing Co., Ltd., thickness 40μm) was changed to protective film "MA-411" (OPP film, manufactured by Oji FTEX Co., Ltd., thickness 15μm) . Except for the above matters, the magnetic thin film 12 was produced in the same manner as in Example 1.

<Comparative Example 2; Production of Magnetic Film 13> In Example 6, the protective film "R033KS" (self-adhesive film, manufactured by Toray Film Processing Co., Ltd., thickness 45μm) was changed to protective film "MA-411" (OPP film, manufactured by Oji FTEX Co., Ltd., thickness 15μm) . Except for the above matters, the magnetic thin film 13 was produced in the same manner as in Example 6.

<Comparative Example 3: Production of Magnetic Film 14> In Example 9, the protective film "FSA-150M" (self-adhesive film, manufactured by Futamura Chemical Co., Ltd., thickness 30μm) was changed to protective film "MA-411" (OPP film, manufactured by Oji FTEX Co., Ltd., thickness 15μm) . Except for the above matters, the magnetic thin film 14 was produced in the same manner as in Example 9.

<Comparative Example 4: Production of Magnetic Film 15> In Example 10, the protective film "FSA-150M" (self-adhesive film, manufactured by Futamura Chemical Co., Ltd., thickness 30μm) was changed to protective film "MA-411" (OPP film, manufactured by Oji FTEX Co., Ltd., thickness 15μm) . Except for the above matters, the magnetic thin film 15 was produced in the same manner as in Example 10.

<Comparative Example 5: Production of Magnetic Film 16> In Example 11, the protective film "FSA-150M" (self-adhesive film, manufactured by FUTAMURA Chemical Co., Ltd., thickness 30μm) was changed to protective film "MA-411" (OPP film, manufactured by Oji FTEX Co., Ltd., thickness 15μm) . Except for the above matters, the magnetic thin film 16 was produced in the same manner as in Example 11.

<Measurement of the lowest melt viscosity of the resin composition layer> For the resin composition layers of the magnetic films 1 to 16, a dynamic viscoelasticity measuring device ("Rheosol-G3000" manufactured by UBM Corporation) was used to measure the melt viscosity. For 1g of the resin composition, using a parallel plate with a diameter of 10mm, the temperature is raised from 60°C to 180°C at a temperature rise rate of 5°C/min. The measurement temperature interval is 2.5°C, the number of vibrations is 1Hz, and the deformation is 0.1deg. The dynamic viscoelasticity rate is obtained by obtaining the lowest value among the complex viscosities, which is defined as the lowest melt viscosity (Poise).

＜Measurement of adhesive force of protective film＞ The protective film was cut into a width of 24 mm and a length of 70 mm, and laminated on a glass slide ("S1112" manufactured by Matsunami Glass Industry Co., Ltd.) at 40°C to obtain a sample to be tested. Peel off one end of the protective film layer and clamp it with a jig, peel off the protective film 15 mm in the vertical direction at a speed of 50 mm/min at room temperature (23°C), measure the load at this time, and obtain the peel strength (adhesion) strength). For the measurement, a tensile tester ("AC-50" manufactured by TSE Corporation) was used.

<Measurement of the adhesion strength between the resin composition layer and the protective film layer> Cut the magnetic films 1-16 into widths of 27 mm and lengths of 70 mm, respectively, and peel off the support to obtain samples to be tested. The copper-clad laminate was cut into a width of 27 mm and a length of 100 mm, and a double-sided tape ("Nicetack" manufactured by Nichiban) was attached to a distance of 70 mm from one end, and then applied to the surface of the resin composition layer of the sample to be tested. Peel off one end of the protective film layer and clamp it with a jig. The protective film is peeled off 15mm in the vertical direction at a speed of 50mm/min at room temperature (23°C), and the load at this time is measured to obtain the peel strength (density). Intensity). For the measurement, a tensile tester ("AC-50" manufactured by TSE Corporation) was used. In addition, the measured adhesion strength was evaluated according to the following criteria. ○: The protective film is attached to the resin composition layer. ×: The protective film is not attached to the resin composition layer.

1: Magnetic film 11: Support 12: Resin composition layer 13: Protective film layer

[Fig. 1] is a schematic cross-sectional view showing an example of a magnetic thin film.

1: Magnetic film

11: Support

12: Resin composition layer

13: Protective film layer

Claims (10)

A magnetic film, which has: Support body, and A resin composition layer formed on the support and formed of a resin composition, and The protective film layer bonded to the surface of the resin composition layer on the opposite side to the support side, and The resin composition contains magnetic powder, The protective film layer is a self-adhesive film. Such as the magnetic film of claim 1, wherein when the non-volatile content of the resin composition is set to 100% by mass, the content of the magnetic powder is 75% by mass or more and 98% by mass or less. The magnetic film of claim 1, wherein the minimum melt viscosity of the resin composition layer is 50,000 poise (Poise) or more and 50,000,000 poise or less. The magnetic film of claim 1, wherein the resin composition is a thermosetting resin composition. The magnetic film of claim 1, wherein the resin composition contains epoxy resin. The magnetic film according to claim 1, wherein the resin composition contains at least any one of a hardening agent and a hardening accelerator. The magnetic film of claim 1, wherein the resin composition contains a thermoplastic resin. The magnetic film of claim 1, wherein the adhesion strength of the protective film layer to the resin composition layer is 0.1 gf/cm or more and 10 gf/cm or less. The magnetic film according to claim 1, wherein the magnetic powder is at least one selected from iron oxide powder and iron alloy metal powder. A method for manufacturing a magnetic thin film, which is the method for manufacturing a magnetic thin film according to any one of claims 1 to 9, and includes: The step of coating a resin varnish containing a resin composition on the support to form a resin composition layer; and The step of laminating a protective film layer on the resin composition layer.

Images