JP6778991B2 - Soft magnetic thermosetting film and soft magnetic film - Google Patents

Description

The present invention relates to soft magnetic thermosetting films and soft magnetic films.

Since parts are densely integrated in small electronic devices such as mobile phones, digital cameras, and laptop computers, high-frequency noise is generated due to electromagnetic interference between the parts. In addition, high-frequency noise also enters from the external environment such as peripheral devices. Since this high-frequency noise may cause a defect in an electronic component, the defect is solved by mounting an electromagnetic wave absorbing sheet inside the electronic device to absorb the high-frequency noise.

As such an electromagnetic wave absorbing sheet, for example, Patent Document 1 discloses an electromagnetic wave absorbing sheet containing a soft magnetic powder, a binder resin, a flame retardant and an acid receiving agent.

By the way, an impedance analyzer is used to measure the electromagnetic wave absorption, and the complex magnetic permeability μ is calculated. Specifically, it is calculated in the form of the formula "μ = μ'+ jμ'". (Μ'is the real part of the complex relative permeability and affects the convergence of the magnetic flux. Μ'is the imaginary part of the complex relative permeability and affects the attenuation of the magnetic flux.)

Of the coefficients of this equation, the higher μ ″, the more efficiently the electromagnetic waves can be converted into thermal energy, so that high-frequency noise can be absorbed even more.

Japanese Unexamined Patent Publication No. 2013-17249

However, in the electromagnetic wave absorption sheet of Patent Document 1, the imaginary portion μ ″ of the complex relative magnetic permeability is insufficient, and further improvement is required.

An object of the present invention is to provide a soft magnetic film having a good imaginary portion μ ″ of complex relative magnetic permeability and a soft magnetic thermosetting film for producing the soft magnetic film.

The soft magnetic thermosetting film of the present invention is a soft magnetic thermosetting film formed from a soft magnetic resin composition, and the soft magnetic resin composition contains flat soft magnetic particles and a resin component. The volume ratio of the soft magnetic particles to the soft magnetic resin composition is 65% by volume or more in terms of solid content, and the specific gravity of the soft magnetic film obtained by thermosetting the soft magnetic thermosetting film is high. It is characterized by being 5.01 or more.

Further, in the soft magnetic thermosetting film of the present invention of the present invention, it is preferable that the resin component contains an epoxy resin, a phenol resin and an acrylic resin.

Further, in the soft magnetic thermosetting film of the present invention, it is preferable that the soft magnetic particles are a Fi—Si—Al alloy.

The soft magnetic film of the present invention is characterized in that it is obtained by heat-curing the above-mentioned soft magnetic thermosetting film.

According to the soft magnetic film obtained from the soft magnetic thermosetting film of the present invention, the imaginary portion μ ″ of the complex relative magnetic permeability is good. Therefore, high frequency noise can be efficiently absorbed.

FIG. 1 shows a cross-sectional view of an embodiment of a soft magnetic film laminated circuit board including the soft magnetic film of the present invention.

The soft magnetic thermosetting film of the present invention is formed in the form of a film (sheet shape) from, for example, a soft magnetic resin composition containing soft magnetic particles and a resin component.

Examples of the soft magnetic material constituting the soft magnetic particles include magnetic stainless steel (Fe-Cr-Al-Si alloy), sentust (Fe-Si-A1 alloy), permalloy (Fe-Ni alloy), and silicon silicon copper (Fe-). Cu-Si alloy), Fe-Si alloy, Fe-Si-B (-Cu-Nb) alloy, Fe-Si-Cr-Ni alloy, Fe-Si-Cr alloy, Fe-Si-Al-Ni-Cr alloy , Ferrite and the like. Among these, sendust (Fe-Si-Al alloy) is preferable from the viewpoint of the imaginary portion of the complex relative magnetic permeability (hereinafter, may be simply abbreviated as the imaginary portion of the magnetic permeability).

The soft magnetic particles are formed in a flat shape (plate shape), that is, in a shape having a thin thickness and a wide surface. The flatness (flatness) of the soft magnetic particles is, for example, 8 or more, preferably 15 or more, and for example, 80 or less, preferably 65 or less. The flatness is calculated as, for example, an aspect ratio obtained by dividing the average particle diameter (average length) of the soft magnetic particles by the average thickness of the soft magnetic particles.

The average particle diameter (average length) of the soft magnetic particles is, for example, 3.5 μm or more, preferably 10 μm or more, and for example, 100 μm or less, preferably 80 μm or less. The average thickness is, for example, 0.3 μm or more, preferably 0.5 μm or more, and for example, 3 μm or less, preferably 2.5 μm or less. By adjusting the flatness, average particle diameter, average thickness, etc. of the soft magnetic particles, the influence of the demagnetic field by the soft magnetic particles can be reduced, and as a result, the magnetic permeability of the soft magnetic particles can be increased. In addition, in order to make the size of the soft magnetic particles uniform, if necessary, the soft magnetic particles classified by using a sieve or the like may be used.

The specific gravity of the soft magnetic particles is, for example, 5.0 or more and 8.0 or less.

The volume ratio of the soft magnetic particles in the soft magnetic resin composition is, for example, 65% by volume or more, preferably 70% by volume or more, and for example, 95% by volume or less, preferably 90% by volume or less in terms of solid content. Is. In terms of solid content, the mass ratio is, for example, more than 85% by mass, preferably 88% by mass or more, more preferably 90% by mass or more, and for example, 98% by mass or less, preferably 98% by mass or less. , 95% by mass or less. By setting the content ratio of the soft magnetic particles to the above lower limit or more, the magnetic permeability imaginary portion μ ″ of the soft magnetic film is excellent. On the other hand, when the content is not more than the above upper limit, the film forming property of the soft magnetic resin composition is excellent.

The volume ratio of each component such as soft magnetic particles is calculated based on the theoretical volume obtained by dividing the mass of each component by the specific gravity of the component. The specific gravity of each component is obtained by a catalog value or a known measuring method (for example, a specific gravity measuring method described later).

The resin component is a resin component having thermosetting property, and preferably contains a thermosetting resin and an acrylic resin. More preferably, it contains a thermosetting resin composed of an epoxy resin and a phenol resin, and an acrylic resin.

Examples of the epoxy resin include bisphenol type epoxy resin, phenol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetraphenylol ethane type epoxy resin and the like. .. Further, for example, a hydantoin type epoxy resin, a trisglycidyl isocyanurate type epoxy resin, a glycidylamine type epoxy resin and the like can be mentioned. These can be used alone or in combination of two or more.

More specifically, the bisphenol type epoxy resin includes a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a brominated bisphenol A type epoxy resin, a hydrogenated bisphenol A type epoxy resin, and a bisphenol AF type epoxy resin. Examples thereof include resins, and preferred examples include bisphenol A type epoxy resins.

Specific examples of the phenol-type epoxy resin include phenol novolac-type epoxy resin and cresol novolac-type epoxy resin, and preferably cresol-novolac-type epoxy resin.

Among these epoxy resins, bisphenol type epoxy resin, phenol type epoxy resin, and trishydroxyphenylmethane type epoxy resin are preferable, and trishydroxyphenylmethane type epoxy resin alone or phenol type epoxy resin is more preferable. And a bisphenol type epoxy resin are used in combination, and the trishydroxyphenylmethane type epoxy resin is most preferable. Specific examples thereof include a trishydroxyphenylmethane type epoxy resin represented by the following general formula (1).

In addition, n shows the degree of polymerization of a monomer.

In particular, the trishydroxyphenylmethane type epoxy resin is an epoxy resin (polyfunctional monomer type epoxy resin) composed of a polyfunctional monomer having two or more functional groups (glycidyl group, etc.) as a repeating unit, so that the melting temperature can be adjusted. It can be lowered and can be crosslinked and cured closely with a phenol resin described later. Therefore, when the soft magnetic resin composition containing the soft magnetic particles in a high content ratio (for example, 65% by volume or more) is compressed to produce a high-density soft magnetic film, the resin due to the repulsive force between the soft magnetic particles. It is possible to suppress cracks in the composition and thus generation of voids (springback), and it is possible to achieve a high specific gravity of the soft magnetic film.

The epoxy equivalent of the epoxy resin is, for example, 10 g / eq. As mentioned above, preferably 100 g / eq. The above, and for example, 500 g / eq. Hereinafter, preferably 180 g / eq. It is as follows.

The viscosity (150 ° C.) of the epoxy resin is, for example, 1.0 Pa · s or less, preferably 0.2 Pa · s or less, and 0.01 Pa · s or more. Viscosity is measured by an ICI viscometer.

The specific gravity of the epoxy resin is, for example, 1.0 or more and 1.5 or less.

The phenolic resin is a thermosetting resin that serves as a curing agent for the epoxy resin, and examples thereof include phenol novolac resin, cresol novolac resin, phenol aralkyl resin, phenol biphenylene resin, dicyclopentadiene type phenol resin, and resol resin. These can be used alone or in combination of two or more.

Among these phenolic resins, phenol novolac resin and phenol biphenylene resin are preferable, and phenol novolac resin is more preferable. By containing these phenolic resins, the reactivity with the epoxy resin is excellent, and the resin strength can be improved.

The hydroxyl group equivalent of the phenol resin is, for example, 10 g / eq. As mentioned above, preferably 80 g / eq. The above, and for example, 500 g / eq. Hereinafter, preferably, 150 g / eq. It is as follows.

The viscosity (150 ° C.) of the phenol resin is, for example, 0.10 Pa · s or less, preferably 0.04 Pa · s or less, and 0.01 Pa · s or more.

The specific gravity of the phenol resin is, for example, 1.0 or more and 1.5 or less.

Further, as a combination of the epoxy resin and the phenol resin, from the viewpoint of obtaining a soft magnetic film having a high specific gravity, (1) a combination of a trishydroxyphenylmethane type epoxy resin as the epoxy resin and a phenol novolac resin as the phenol resin is preferable. (2) Examples of the epoxy resin include a combination of a cresol novolac type epoxy resin and a bisfer type epoxy resin, and a phenol biphenylene resin as a phenol resin. More preferably, the combination of (1) can be mentioned.

In particular, by using a phenol novolac resin capable of shortening the cross-linking point distance with respect to the trishydroxyphenylmethane type epoxy resin having a plurality of functional groups in the repeating unit, the trishydroxyphenylmethane type epoxy resin and the phenol novolac resin Can be cross-linked densely with each other, and a cured resin having higher strength can be obtained. Therefore, the springback of the soft magnetic particles can be reliably suppressed, and a soft magnetic film having a particularly high specific gravity can be obtained.

The acrylic resin includes, for example, an acrylic polymer obtained by polymerizing one or more (meth) acrylic acid alkyl esters having a linear or branched alkyl group as monomer components. Can be mentioned. In addition, "(meth) acrylic" represents "acrylic and / or methacrylic".

Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, t-butyl group, isobutyl group, amyl group, isoamyl group, hexyl group, heptyl group, cyclohexyl group and 2-. Alkyl having 1 to 20 carbon atoms such as ethylhexyl group, octyl group, isooctyl group, nonyl group, isononyl group, decyl group, isodecyl group, undecyl group, lauryl group, tridecyl group, tetradecyl group, stearyl group, octadecyl group and dodecyl group. Group is mentioned. Preferred are alkyl groups having 1 to 6 carbon atoms.

The acrylic polymer may be a copolymer of a (meth) acrylic acid alkyl ester and another monomer.

Examples of other monomers include glycidyl group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, and carboxyl groups such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Containing monomers, such as acid anhydride monomers such as maleic anhydride and itaconic anhydride, such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate. , (Meta) acrylate 6-hydroxyhexyl, (meth) acrylate 8-hydroxyoctyl, (meth) acrylate 10-hydroxydecyl, (meth) acrylate 12-hydroxylauryl or (4-hydroxymethylcyclohexyl) -methyl Hydroxyl group-containing monomers such as acrylates, such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) Examples thereof include sulfonic acid group-containing monomers such as acryloyloxynaphthalene sulfonic acid and phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate, such as styrene monomers, such as acrylonitrile. These can be used alone or in combination of two or more. Among these, acrylonitrile is preferably mentioned.

In addition, the acrylic resin preferably has an epoxy group. When the acrylic resin has an epoxy group, the epoxy value is, for example, 10 eq. / G or more, preferably 100 eq. / G or more, and for example, 800 eq. / G or less, preferably 500 eq. It is less than / g.

The weight average molecular weight of acrylic resin, for example, 1 × 10 ⁵ or more, preferably not 3 × 10 ⁵ or more, and for example, is 1 × 10 ⁶ or less. The weight average molecular weight is measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

The glass transition temperature (Tg) of the acrylic resin is, for example, −20 ° C. or higher, preferably 0 ° C. or higher, more preferably 10 ° C. or higher, still more preferably 12 ° C. or higher. Further, for example, it is 50 ° C. or lower, preferably 30 ° C. or lower. By setting the Tg of the acrylic resin to the above lower limit or more, the strength of the resin component can be improved, springback can be suppressed, and the specific gravity of the soft magnetic film can be increased. In addition, the handling of the soft magnetic film and the adhesiveness of the soft magnetic thermosetting film in a semi-cured state are excellent. The glass transition temperature is obtained from the maximum value of the loss tangent (tan δ) measured using a dynamic viscoelasticity measuring device (DMA, frequency 1 Hz, tensile mode, heating rate 10 ° C./min).

The specific gravity of the acrylic resin is, for example, 0.6 or more and 1.0 or less.

The resin component may also contain a thermosetting resin and other resins other than the acrylic resin.

Examples of such resins include natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymer, polybutadiene resin, polycarbonate resin, thermoplastic polyimide resin, and polyamide resin (6-nylon, 6,6- Nylon, etc.), phenoxy resin, saturated polyester resin (PET, PBT, etc.), polyamideimide resin, fluororesin, and the like. These can be used alone or in combination of two or more.

The volume ratio of the resin component in the soft magnetic resin composition is, for example, 5% by volume or more, preferably 10% by volume or more, and for example, 35% by volume or less, preferably 30% by volume in terms of solid content. It is as follows. The mass ratio of the resin component in the soft magnetic resin composition is, for example, 2% by mass or more, preferably 5% by mass or more, and for example, less than 15% by mass, preferably 12% by mass in terms of solid content. Hereinafter, it is more preferably 10% by mass or less. When the content ratio of the resin component is within the above range, the film forming property on the soft magnetic thermosetting film and the magnetic permeability imaginary portion μ ″ are excellent.

The volume ratio of the thermosetting resin (preferably a thermosetting resin composed of an epoxy resin and a phenol resin) in the resin component is, for example, 85% by volume or more, preferably 90% by volume or more, more preferably 95% by volume. The above, and for example, 99% by volume or less, preferably 97% by volume or less.

The volume ratio of the epoxy resin in the resin component is, for example, 10% by volume or more, preferably 30% by volume or more, more preferably more than 50% by volume, and for example, 90% by volume or less, preferably 80% by volume. % Or less, more preferably 70% by volume or less. The mass ratio of the epoxy resin in the resin component is, for example, 10% by mass or more, preferably 30% by mass or more, more preferably more than 50% by mass, and for example, 90% by mass or less, preferably 80% by mass. % Or less, more preferably 70% by mass or less.

The volume ratio of the phenol resin in the resin component is, for example, 10% by volume or more, preferably 20% by volume or more, more preferably more than 30% by volume, and for example, 90% by volume or less, preferably 70% by volume. % Or less, more preferably less than 50% by volume. The mass ratio of the phenol resin in the resin component is, for example, 10% by mass or more, preferably 20% by mass or more, more preferably more than 30% by mass, and for example, 90% by mass or less, preferably 70% by mass. % Or less, more preferably less than 50% by mass.

The content ratio of the phenol resin to 100 parts by volume of the epoxy resin is, for example, 10 parts by volume or more, preferably 50 parts by volume or more, and for example, 200 parts by volume or less, preferably less than 100 parts by volume. ..

The volume ratio of the acrylic resin in the resin component is, for example, 1% by volume or more, preferably 3% by volume or more, and for example, 25% by volume or less, preferably 15% by volume or less, more preferably 10% by volume. % Or less, more preferably 5% by volume or less. The mass ratio of the acrylic resin in the resin component is, for example, 1% by mass or more, preferably 3% by mass or more, and for example, 25% by mass or less, preferably 15% by mass or less, more preferably 10% by mass. % Or less, more preferably 5% by mass or less. When the content ratio of the acrylic resin is within the above range, the specific gravity of the soft magnetic film can be further increased.

The soft magnetic resin composition preferably contains a thermosetting catalyst.

The thermosetting catalyst is not limited as long as it is a catalyst that accelerates the curing of the resin component by heating, and examples thereof include imidazole compounds, triphenylphosphine compounds, triphenylborane compounds, and amino group-containing compounds. Be done. Preferably, an imidazole compound is used.

Examples of the imidazole compound include 2-phenylimidazole (trade name: 2PZ), 2-ethyl-4-methylimidazole (trade name: 2E4MZ), 2-methylimidazole (trade name: 2MZ), and 2-undecylimidazole. (Product name; C11Z), 2-phenyl-1H-imidazole 4,5-dimethanol (trade name: 2PHZ-PW), 2,4-diamino-6- (2'-methylimidazolyl (1)') ethyl- Examples thereof include s-triazine isocyanuric acid adduct (trade name; 2MAOK-PW) (the above product names are all manufactured by Shikoku Kasei Co., Ltd.). These can be used alone or in combination of two or more.

The specific gravity of the thermosetting catalyst is, for example, 0.9 or more and 1.5 or less.

The content ratio of the thermosetting catalyst is, for example, 0.1 part by volume or more, preferably 0.3 part by volume or more, and for example, 5 parts by volume or less, preferably 5 parts by volume, based on 100 parts by volume of the resin component. It is 3 parts by volume or less. The mass ratio of the thermosetting catalyst is, for example, 0.1 part by mass or more, preferably 0.3 part by mass or more, and for example, 5 parts by mass or less, preferably 5 parts by mass or more, relative to 100 parts by mass of the resin component. It is 3 parts by mass or less. By setting the content ratio of the thermosetting catalyst within the above range, the soft magnetic resin composition can be heat-cured at a low temperature in a short time, and the heat resistance is excellent.

The soft magnetic resin composition can also contain a rheology control agent. When the soft magnetic resin composition contains a rheology control agent, the soft magnetic particles can be more uniformly dispersed in the soft magnetic thermosetting film (and thus the soft magnetic film).

The rheology control agent is a compound that imparts thixotropic properties to the soft magnetic resin composition, which exhibits high viscosity when the shearing force (shearing velocity) is low and low viscosity when the shearing force (shearing velocity) is high. is there.

Examples of the rheology control agent include an organic rheology control agent and an inorganic rheology control agent. Preferred are organic rheology control agents.

Examples of the organic rheology control agent include modified urea, urea-modified polyamide, fatty acid amide, polyurethane, and a high molecular weight urea derivative. Preferred are modified urea, urea-modified polyamide, and fatty acid amide, and more preferably, urea-modified polyamide.

Examples of the inorganic rheology control agent include silica, calcium carbonate, smectite and the like.

Specific examples of the rheology control agent include "BYK-410", "BYK-430", and "BYK-431" manufactured by Big Chemie, and "Disparon PFA-131" manufactured by Kusumoto Kasei Co., Ltd., for example, Japan. Examples thereof include Aerosil's "Aerosil VP NK200", "Aerosil R976S", and "Aerosil COK84".

These can be used alone or in combination of two or more.

The specific gravity of the rheology control agent is, for example, 0.6 or more and 1.0 or less.

The volume ratio of the rheology control agent is, for example, 0.1 part by volume or more, preferably 1 part by volume or more, and for example, 10 parts by volume or less, preferably 5 parts by volume with respect to 100 parts by volume of the resin component. It is less than a part. The mass ratio of the rheology control agent is, for example, 0.1 part by mass or more, preferably 1 part by mass or more, and for example, 10 parts by mass or less, preferably 5 parts by mass with respect to 100 parts by mass of the resin component. It is less than a part.

The soft magnetic resin composition may further contain other additives, if desired. Examples of the additive include commercially available or known additives such as a dispersant, a cross-linking agent, and an inorganic filler.

The soft magnetic resin composition is prepared by mixing the above components in the above content ratio.

The soft magnetic thermosetting film is dried, for example, in a preparation step of preparing a soft magnetic resin composition solution by dissolving or dispersing the soft magnetic resin composition in a solvent, applying it to the surface of a release base material, and drying it. It can be manufactured by the process.

First, the soft magnetic resin composition is dissolved or dispersed in a solvent (preparation step). As a result, a soft magnetic resin composition solution is prepared.

As the solvent, for example, ketones such as acetone and methyl ethyl ketone (MEK), for example, esters such as ethyl acetate, for example, ethers such as propylene glycol monomethyl ether, for example, amides such as N, N-dimethylformamide and the like. Examples include organic solvents. Further, as the solvent, for example, water, for example, an aqueous solvent such as alcohol such as methanol, ethanol, propanol and isopropanol can also be mentioned.

The solid content in the soft magnetic resin composition solution is, for example, 1% by mass or more, preferably 5% by mass or more, and for example, 90% by mass or less, preferably 70% by mass or less.

Next, the soft magnetic resin composition solution is applied to the surface of the release base material (separator, core material, etc.) and dried (drying step).

The coating method is not particularly limited, and examples thereof include a doctor blade method, roll coating, screen coating, and gravure coating.

As the drying conditions, the drying temperature is, for example, 70 ° C. or higher and 160 ° C. or lower, and the drying time is, for example, 1 minute or more and 5 minutes or less.

Examples of the separator include polyethylene terephthalate (PET) film, polyethylene film, polypropylene film, paper and the like. These are released on their surfaces with, for example, a fluorine-based release agent, a long-chain alkyl acrylate-based release agent, a silicone-based release agent, or the like.

Examples of the core material include plastic films (for example, polyimide films, polyester films, polyethylene terephthalate films, polyethylene naphthalate films, polycarbonate films, etc.), metal films (for example, aluminum foil, etc.), for example, glass fibers and plastics. Examples thereof include a resin substrate reinforced with woven fibers, a silicone substrate, and a glass substrate.

The average thickness of the separator or core material is, for example, 1 μm or more and 500 μm or less.

As a result, a soft magnetic thermosetting film is obtained.

The soft magnetic thermosetting film is a soft magnetic thermosetting adhesive film that is in a semi-cured state (B stage state) at room temperature (specifically, 25 ° C.) and has good adhesiveness. Therefore, the soft magnetic thermosetting film (and thus the soft magnetic film) can be arranged and fixed to the object without using an adhesive, and the film can be thinned.

The average thickness of the soft magnetic thermosetting film is, for example, 5 μm or more, preferably 50 μm or more, and for example, 500 μm or less, preferably 250 μm or less.

The soft magnetic thermosetting film is, for example, a single layer structure consisting of only a single layer of the soft magnetic thermosetting film, a multilayer structure in which a soft magnetic thermosetting film is laminated on one side or both sides of a core material, and a soft magnetic thermosetting film. It can be in the form of a multilayer structure in which separators are laminated on one side or both sides of the sex film.

Next, the soft magnetic film will be described.

The soft magnetic film is formed from the above soft magnetic thermosetting film. Specifically, the soft magnetic film is obtained by heat-curing the above-mentioned soft magnetic thermosetting film.

Preferably, a plurality of soft magnetic thermosetting films are prepared, and the plurality of soft magnetic thermosetting films are hot pressed in the thickness direction by hot pressing (heat pressing step). As a result, the soft magnetic particles can be oriented at a high density in the soft magnetic thermosetting film, and a high specific gravity can be achieved.

The hot press can be carried out using a known press, and examples thereof include a parallel flat plate press.

The number of laminated soft magnetic thermosetting films is, for example, two or more layers, and for example, 20 layers or less, preferably 5 layers or less. Thereby, the soft magnetic film having a desired thickness can be adjusted.

The heating temperature is, for example, 80 ° C. or higher, preferably 100 ° C. or higher, and for example, 200 ° C. or lower, preferably 180 ° C. or lower.

The heating time is, for example, 0.1 hours or more, preferably 0.2 hours or more, and for example, 24 hours or less, preferably 2 hours or less.

The pressure is, for example, 10 MPa or more, preferably 20 MPa or more, and for example, 500 MPa or less, preferably 200 MPa or less.

As a result, the soft magnetic thermosetting film is heat-cured, and a soft magnetic film in a cured state (C stage state) is obtained.

The average thickness of this soft magnetic film is, for example, 5 μm or more, preferably 50 μm or more, and for example, 500 μm or less, preferably 250 μm or less.

The specific gravity of the soft magnetic film is 5.01 or more. It is preferably 5.10 or more. Further, for example, it is 6.51 or less, more preferably 6.23 or less. As a result, the magnetic permeability imaginary portion μ ″ of the soft magnetic film is excellent.

The specific gravity (SG) is determined by the specific gravity measurement method using an electronic analysis balance (manufactured by Shimadzu Corporation, "AEL-200"), and the weight of the soft magnetic film in air is W1 (g) and in water. The weight (g) of the soft magnetic film W2 is measured and calculated by the following formula.

Specific gravity (SG) = W1 / (W1-W2)
In the soft magnetic film, preferably, flat soft magnetic particles contained in the soft magnetic film are arranged in a two-dimensional in-plane direction of the soft magnetic film. That is, the longitudinal direction (direction orthogonal to the thickness direction) of the flat soft magnetic particles is oriented along the plane direction of the soft magnetic film. As a result, the soft magnetic film is filled with soft magnetic particles at a high density and has an excellent magnetic permeability imaginary portion μ ″.

The soft magnetic film exhibits, for example, a magnetic permeability imaginary portion μ ″ (maximum magnetic permeability imaginary portion) having a maximum value of 60 or more in a high frequency region (specifically, 1 MHz or more, preferably 10 to 100 MHz). .. The maximum magnetic permeability imaginary portion μ ″ is preferably 65 or more, and is, for example, 100 or less.

The magnetic permeability imaginary portion μ ″ of the soft magnetic film is, for example, 50 or more, preferably 55 or more, and for example, 100 or less in the entire high frequency range (particularly, 10 to 100 MHz).

The magnetic permeability imaginary portion μ ″ is measured by the one-turn method using an impedance analyzer (manufactured by Agilent, “4294A”).

This soft magnetic film has, for example, a single layer structure consisting of only a single layer of the soft magnetic film, a multilayer structure in which the soft magnetic film is laminated on one side or both sides of the core material, and a separator laminated on one side or both sides of the soft magnetic film. It can be in the form of a multi-layer structure or the like.

Further, in the above embodiment, a plurality of soft magnetic thermosetting films are laminated and heat-pressed, but for example, one soft magnetic thermosetting film (single layer) may be heat-pressed. ..

According to the soft magnetic film, the soft magnetic resin contains flat soft magnetic particles and a resin component, and the volume ratio of the soft magnetic particles to the soft magnetic resin composition is 65% by volume or more in terms of solid content. Since it is formed from the composition and the specific gravity of the soft magnetic film is 5.01 or more, the soft magnetic film has an excellent magnetic permeability imaginary portion μ ″. Therefore, high frequency noise can be reliably absorbed.

This soft magnetic film can be used for various purposes, for example, an electromagnetic wave absorption sheet, in particular, electromagnetic wave absorption for absorbing high frequency (for example, 1 MHz or more, preferably 10 to 100 MHz) electromagnetic waves (noise, etc.). It can be suitably used as a sheet.

Specifically, this soft magnetic film is, for example, as shown in FIG. 1, a circuit board 2, an adhesive layer 3 arranged on the lower surface (one side) of the circuit board 2, and the lower surface of the adhesive layer 3. It can be used as a soft magnetic film laminated substrate 1 including a soft magnetic film 4 arranged in.

The circuit board 2 is, for example, a circuit board 2 used in an electromagnetic induction method, and a wiring pattern 6 such as a loop coil is formed on the upper surface (one side) of the substrate 5. The wiring pattern 6 is formed by a semi-additive method, a subtractive method, or the like.

Examples of the insulating material constituting the substrate 5 include a glass epoxy substrate, a glass substrate, a PET substrate, a Teflon substrate, a ceramics substrate, a polyimide substrate, and the like.

As the adhesive layer 3, a known one usually used as an adhesive for the circuit board 2 is used, and for example, an adhesive such as an epoxy adhesive, a polyimide adhesive, or an acrylic adhesive is applied and dried. Is formed by. The thickness of the adhesive layer 3 is, for example, 10 to 100 μm.

The soft magnetic film 4 is the above-mentioned soft magnetic film, in which flat soft magnetic particles 7 are dispersed in a soft magnetic resin composition (specifically, a cured resin 8 in which a resin component is cured). Preferably, the soft magnetic particles 7 are oriented so that their longitudinal direction (direction orthogonal to the thickness direction) is along the plane direction of the soft magnetic film 4.

Such a soft magnetic film laminated substrate 1 can be used, for example, in applications such as mobile phones such as smartphones, digital cameras, and electronic devices such as notebook computers.

In the embodiment of FIG. 1, the adhesive layer 3 is provided between the circuit board 2 and the soft magnetic film 4. For example, although not shown, the soft magnetic film 4 is in direct contact with the circuit board 2. It can also be provided as follows.

In order to directly laminate the soft magnetic film 4 on the circuit board 2, the soft magnetic thermosetting film is directly attached to the circuit board 2, and then the soft magnetic thermosetting film is heat-cured.

According to the soft magnetic film laminated substrate 1, since the soft magnetic film 4 is provided, it is possible to absorb high frequency noise generated from the wiring circuit and noise entering from the outside.

Examples and Comparative Examples will be shown below to describe the present invention in more detail, but the present invention is not limited to the Examples and Comparative Examples. In addition, specific numerical values such as the compounding ratio (content ratio), physical property values, and parameters used in the following description are the compounding ratios corresponding to those described in the above-mentioned "Form for carrying out the invention". Substitute the upper limit value (value defined as "less than or equal to" or "less than") or the lower limit value (value defined as "greater than or equal to" or "exceeded") such as content ratio), physical property value, and parameters. be able to.

Example 1
500 parts by mass (70.0% by volume, the following volume% is solid) of the Fe—Si—Al alloy so that the volume ratio of the soft magnetic particles to the soft magnetic resin composition is 70.0% by volume in terms of solid content. ), Trishydroxyphenylmethane type epoxy resin (EPPN-501HY) 21.9 parts by volume (17.0% by volume), phenol novolac resin (LVR8210DL) 13.5 parts by volume (10.4% by volume), Acrylic ester-based copolymer solution (SG-P3) 8.6 parts by volume (1.4% by volume), imidazole-based compound (heat curing catalyst, 2PHZ-PW) 0.36 parts by volume (0.2% by volume) , And 3.0 parts by volume (1.0% by volume) of a urea-modified polyamide solution (leology control agent, BYK430) was mixed to obtain a soft magnetic resin composition.

By dissolving this soft magnetic resin composition in methyl ethyl ketone, a soft magnetic resin composition solution having a solid content concentration of 7.0% by mass was prepared.

This soft magnetic resin composition solution was applied on a separator (polyethylene terephthalate film that had been subjected to silicone release treatment), and then dried at 130 ° C. for 2 minutes. As a result, a semi-cured soft magnetic thermosetting film (average thickness 50 μm) was produced.

Next, four layers of this soft magnetic thermosetting film were laminated and heat-cured by a hot press at 175 ° C. for 30 minutes at 160 MPa to prepare a completely cured soft magnetic film (average thickness 150 μm). did.

Example 2
A soft magnetic resin composition was obtained with the materials and blending ratios shown in Table 1. Specifically, 500 parts by mass (70.0% by volume) of Fe-Si-Al alloy, 12.2 parts by mass (9.5% by volume) of bisphenol A type epoxy resin (Epicoat YL980), cresol novolac type epoxy resin ( KI-3000-4) 4.5 parts by mass (3.5% by volume), phenol biphenylene resin (MEH-7851-SS) 18.4 parts by mass (14.4% by volume), acrylic acid ester-based copolymer solution (SG-P3) 12.3 parts by mass (1.4% by volume), imidazole-based compound (heat curing catalyst, 2PHZ-PW) 0.35 parts by mass (0.2% by volume), and urea-modified polyamide solution ( A soft magnetic resin composition was obtained by mixing 3.0 parts by mass (1.0% by volume) of a rheology control agent, BYK430).

The soft magnetic film of Example 2 was produced in the same manner as in Example 1 except that this soft magnetic resin composition was used.

Comparative Examples 1-2
A soft magnetic resin composition was obtained with the materials and blending ratios shown in Table 1. A soft magnetic film of Comparative Example was produced in the same manner as in Example 1 except that this soft magnetic resin composition was used.

(Measurement of specific gravity)
The specific gravity (SG) of the soft magnetic film of each Example and each Comparative Example was measured by a specific gravity measurement method using an electronic analysis balance (manufactured by Shimadzu Corporation, "AEL-200"). The weight W1 (g) of the film and the weight (g) of the soft magnetic film W2 in water were measured and calculated by the following formulas.

Specific gravity (SG) = W1 / (W1-W2)
The results are shown in Table 1.

(Measurement of complex relative permeability)
The complex relative magnetic permeability of the soft magnetic films of each Example and each Comparative Example was measured by a one-turn method using an impedance analyzer (manufactured by Agilent, "4294A").

Table 1 shows the maximum value of the imaginary part μ ″ of the complex relative magnetic permeability at a frequency of 10 MHz or more and the minimum value of the imaginary part μ ″ of the complex relative magnetic permeability at a frequency of 10 to 100 MHz.

The numerical value in each component in the table indicates the solid content. The details of each example and the abbreviation of each component in the table are described below.
-Fe-Si-Al alloy: trade name "FME3DH", soft magnetic particles, flat, average particle diameter 43 μm, average thickness 1 μm, specific gravity 6.8, manufactured by Sanyo Special Steel Co., Ltd. ・ Trishydroxyphenylmethane type epoxy resin: product Name "EPPN-501HY", epoxy resin of the above general formula (1), epoxy equivalent 169 g / eq. , ICI viscosity (150 ° C.) 0.1 Pa · s, specific gravity 1.25, manufactured by Nippon Kayaku Co., Ltd. Cresol novolac type resin: trade name "KI-3000-4", epoxy equivalent 199 g / eq. , ICI viscosity (150 ° C.) 0.4 Pa · s, specific gravity 1.21, manufactured by Toto Kasei Co., Ltd., bisphenol A type epoxy resin: trade name "Epicoat YL980", epoxy equivalent 180 g / eq. , ICI viscosity (150 ° C.) 0.05 Pa · s, specific gravity 1.15, Mitsubishi Chemical Corporation, phenol novolac resin: trade name "Resitop LVR8210DL", hydroxyl group equivalent 104 g / eq. , ICI viscosity (150 ° C.) 0.03 Pa · s, specific gravity 1.2, manufactured by Gun Ei Chemical Industry Co., Ltd., phenol biphenylene resin: trade name "MEH-7851SS", hydroxyl group equivalent 203 g / eq. , ICI viscosity (150 ° C.) 0.05 Pa · s, specific gravity 1.18, manufactured by Meiwa Kasei Co., Ltd. SG-P3: Acrylonitrile copolymer solution, trade name "Taisan Resin SG-P3", containing epoxy group Ethyl acrylate-butyl acrylate-acrylonitrile copolymer, specific gravity 0.85, weight average molecular weight 850,000, epoxy value 210 eq. / G, glass transition temperature 12 ° C., rubber content 15% by mass, solvent: methyl ethyl ketone, manufactured by Nagase ChemteX Corporation SG-70L: acrylic acid ester copolymer solution, trade name "Taisan Resin SG-70L", carboxy Ethyl acrylate-butyl acrylate-acrylonitrile copolymer containing groups and hydroxy groups, specific gravity 1.00, weight average molecular weight 900,000, glass transition temperature -13 ° C, rubber content 12.5% by mass, solvent: methyl ethyl ketone And toluene mixture, 2PHZ-PW manufactured by Nagase ChemteX Co., Ltd .: thermocuring catalyst, 2-phenyl-1H-imidazole 4,5-dimethanol, specific gravity 1.33, trade name "Curesol 2PHZ-PW", Shikoku Kasei BYK430: Trade name, Leology control agent, urea-modified medium-polar polymer, specific gravity 0.86, solid content 30% by mass, mixture of isobutyl alcohol and solvent naphtha, manufactured by Big Chemie Japan

4 Soft magnetic film 7 Soft magnetic particles

Claims (3)

A soft magnetic thermosetting film formed from a soft magnetic resin composition.
The soft magnetic resin composition contains flat soft magnetic particles and a resin component.
The soft magnetic particles are a Fi—Si—Al alloy and
The volume ratio of the soft magnetic particles to the soft magnetic resin composition is 65% by volume or more in terms of solid content.
The soft magnetic thermosetting film is obtained by thermally curing the soft magnetic thermosetting film at 175 ° C. for 30 minutes at 160 MPa by a hot press, and the specific gravity of the soft magnetic film is 5.01 or more. Sex film. The soft magnetic thermosetting film according to claim 1, wherein the resin component contains an epoxy resin, a phenol resin, and an acrylic resin. Ri thermosets der of the soft magnetic thermosetting film according to claim 1 or 2,
Specific gravity, characterized in der Rukoto 5.01 or more, the soft magnetic film.

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