TWI652703B - Soft magnetic film - Google Patents

Abstract

The soft magnetic film of the present invention is a soft magnetic film containing flat soft magnetic particles. At a temperature rise rate 10 ℃ / min, the tensile elasticity was measured under the dynamic viscosity frequency of 1Hz in 200 ℃ storage modulus E 'at _{200 is} the 23 deg.] C and a tensile storage modulus E' ₂₃ ratio of E _'200 / E' ₂₃ is 0.25 or more.

Description

Soft magnetic film

The present invention relates to a soft magnetic film.

A position detecting device that moves a pen type position indicator on a position detecting plane to detect a position is called a digitizer, and is popular as an input device of a computer. The position detecting device includes a position detecting plane plate and a circuit board (sensor substrate) disposed below the substrate and having a loop coil formed on the surface of the substrate. And, the position of the position indicator is detected by utilizing electromagnetic induction generated by the position indicator and the loop coil.

In order to improve the communication efficiency in order to control the magnetic flux generated when the electromagnetic induction is applied to the position detecting device, it is proposed to arrange a soft magnetic film containing a soft magnetic substance on the surface (opposite side) of the sensor substrate opposite to the position detecting plane. The method (for example, refer to Patent Document 1).

Patent Document 1 discloses a soft magnetic film containing a soft magnetic powder, a binder resin including an acrylic rubber, a phenol resin, an epoxy resin, and melamine, and a metal phosphonate salt. The soft magnetic film contains a metal phosphonic acid salt or melamine at a high ratio, thereby imparting flame retardancy to the circuit substrate without affecting the reliability of the electronic device.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-212790

Further, the soft magnetic film is mounted on the circuit board, and then the reflow step is performed. but When the magnetic film is subjected to a high temperature treatment of more than 200 ° C, such as a reflow step, the magnetic properties such as relative magnetic permeability are deteriorated.

An object of the present invention is to provide a soft magnetic film which can suppress deterioration of magnetic properties even after the reflow step.

The soft magnetic film of the present invention is characterized in that it is a flat-packed soft magnetic particle, and the tensile storage modulus E' at 200 ° C in a dynamic viscoelasticity measurement at a heating rate of 10 ° C/min and a frequency of 1 Hz. a tensile storage modulus E of ₂₀₀ and 23 deg.] C under the _'23 ratio of E' ₂₀₀ / E _'23 is 0.25 or more.

Further, the soft magnetic film of the present invention preferably has a tensile storage modulus E' ₂₀₀ at 200 ° C of 8.0 × 10 ⁸ Pa or more.

Further, the soft magnetic film of the present invention is preferably formed of a soft magnetic resin composition containing an epoxy resin, a phenol resin, and an acrylic resin.

Moreover, in the soft magnetic resin composition of the present invention, the total content of the epoxy resin and the phenol resin is preferably 100 parts by mass of the soft magnetic particle-excluding component other than the soft magnetic particles. 20 parts by mass or more and 99 parts by mass or less.

Further, the soft magnetic film of the present invention is preferably 30% by volume or more and 70% by volume.

Further, the soft magnetic film of the present invention is preferably in a hardened state.

The soft magnetic film of the present invention can suppress deterioration of magnetic properties even after high-temperature treatment such as a reflow step, and has excellent magnetic properties.

The soft magnetic hot film of the present invention is formed into a film shape (sheet shape), for example, from a soft magnetic 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), Zendust (Fe-Si-Al alloy), and Permalloy. (Fe-Ni alloy), beryllium 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, a tridext alloy (Fe-Si-Al alloy) is preferably exemplified in terms of magnetic properties.

Among these, an Fe-Si-Al alloy having a Si content ratio of 9 to 15% by mass can be more preferably exemplified. Thereby, the magnetic properties of the soft magnetic film can be improved.

The soft magnetic particles are formed into a flat shape (plate shape), that is, a shape having a small thickness and a wide surface. The flatness (flatness) of the soft magnetic particles is, for example, 8 or more, preferably 15 or more, and is, for example, 80 or less, preferably 65 or less. The flatness ratio can be calculated, for example, by dividing the average particle diameter (average length) of the soft magnetic particles by the aspect ratio obtained by dividing 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 is, for example, 100 μm or less. The average thickness is, for example, 0.3 μm or more, preferably 0.5 μm or more, and is, for example, 3 μm or less, or preferably 2.5 μm or less. By adjusting the flatness ratio, the average particle diameter, the average thickness, and the like of the soft magnetic particles, the influence of the demagnetizing field by the soft magnetic particles can be reduced, and as a result, the magnetic permeability of the soft magnetic particles can be increased. Further, in order to make the size of the soft magnetic particles uniform, it is also possible to use soft magnetic particles classified by a sieve or the like as needed.

The mass ratio of the soft magnetic particles in the soft magnetic resin composition (further, the soft magnetic film) is, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 85% by mass or more, and further, for example, 95. The mass% or less is preferably 92% by mass or less, more preferably 90% by mass or less. The volume ratio of the soft magnetic particles in the soft magnetic resin composition is, for example, 30% by volume or more, preferably 40% by volume or more, more preferably 50% by volume or more, and further, for example, 80% by volume or less, preferably 70% by volume. % or less, more preferably 60% by volume or less. By setting The soft magnetic film is excellent in moldability in the range of the upper limit or less. On the other hand, the magnetic properties of the soft magnetic film are excellent by setting the range of the lower limit or more.

The resin component may contain any of a thermosetting resin and a thermoplastic resin, and preferably contains a thermosetting resin.

Examples of the thermosetting resin include an epoxy resin, a phenol resin, an amine resin, an unsaturated polyester resin, a polyurethane resin, a polyoxyl resin, a urea resin, a melamine resin, and a thermosetting polyimide resin. Diallyl phthalate resin and the like. An epoxy resin or a phenol resin is preferably used, and a combination of an epoxy resin and a phenol resin can be more preferably used. These may be used alone or in combination of two or more.

The epoxy resin can be used, for example, as an adhesive composition, and examples thereof include a bisphenol type epoxy resin (especially a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, Brominated bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, bisphenol AF type epoxy resin, etc.), phenol type epoxy resin (especially, phenol novolac type epoxy resin, o-cresol novolac) A varnish-type epoxy resin, etc., a biphenyl type epoxy resin, a naphthalene type epoxy resin, a fluorene type epoxy resin, a trishydroxyphenylmethane type epoxy resin, a tetraphenol ethane type epoxy resin, or the like. Further, for example, an intramethylene urethane type epoxy resin, a isocyanuric acid triglycidyl type epoxy resin, a glycidylamine type epoxy resin, or the like may be mentioned. These may be used alone or in combination of two or more.

Among these epoxy resins, a bisphenol type epoxy resin is preferable, and a bisphenol A type epoxy resin can be more preferably mentioned. By containing an epoxy resin, it is excellent in reactivity with a phenol resin, and as a result, the soft magnetic film is excellent in reflow resistance.

The phenol resin is a curing agent for an epoxy resin, and examples thereof include a phenol novolak resin, a phenol aralkyl resin, a cresol novolak resin, a third butyl phenol novolak resin, and a nonylphenol novolak resin. A phenol resin such as a resol type phenol resin such as polyhydroxystyrene such as polyparaxyl styrene. These may be used alone or in combination of two or more.

Among these phenol resins, a novolak type resin is preferably exemplified, and a phenol novolak resin or a phenol aralkyl resin can be more preferably exemplified, and a phenol aralkyl resin can be further preferably exemplified. By containing these phenol resins, the reactivity with an epoxy resin is excellent, and as a result, the soft magnetic film is excellent in the reflow resistance.

When the epoxy resin and the phenol resin are used in combination with the resin component, when the hydroxyl equivalent of the phenol resin is 1 g/eq or more and less than 100 g/eq with respect to the epoxy equivalent of the epoxy resin of 100 g/eq, the epoxy resin is relative to the epoxy resin. The content ratio of the resin component is, for example, 15 parts by mass or more, preferably 30 parts by mass or more, more preferably 45 parts by mass or more, and for example, 70 parts by mass or less, preferably 50 parts by mass or less, of phenol. The content ratio of the resin to 100 parts by mass of the resin component is, for example, 5 parts by mass or more, preferably 15 parts by mass or more, and for example, 30 parts by mass or less, preferably 25 parts by mass or less.

When the hydroxyl equivalent of the phenol resin is 100 g/eq or more and less than 200 g/eq with respect to the epoxy equivalent 100 g/eq of the epoxy resin, the content ratio of the epoxy resin to 100 parts by mass of the resin component is, for example, 10 mass. The content of the phenol resin to 100 parts by mass of the resin component is, for example, 10 parts by mass or more, preferably 25 parts by mass or more, more preferably 25 parts by mass or more, and further preferably 25 parts by mass or more. For example, it is also 50 parts by mass or less.

When the hydroxyl equivalent of the phenol resin is 200 g/eq or more and 1000 g/eq or less with respect to the epoxy equivalent 100 g/eq of the epoxy resin, the content ratio of the epoxy resin to 100 parts by mass of the resin component is, for example, 5 parts by mass. The content ratio of the phenol resin to 100 parts by mass of the resin component is, for example, 15 parts by mass or more, preferably 35 parts by mass or more, and more preferably, for example, 15 parts by mass or more. It is also 70 mass parts or less.

Furthermore, the epoxy equivalent of the two epoxy resins is used to multiply the epoxy equivalent of each epoxy resin by the mass ratio of each epoxy resin to the total amount of the epoxy resin, and then add them together. Epoxy equivalent of all epoxy resins.

In addition, the hydroxyl group equivalent of the phenol resin is, for example, 0.2 equivalent or more, preferably 0.5 equivalent or more, and also 2.0 equivalents or less, preferably 1.2 equivalents or less, per equivalent of the epoxy group of the epoxy resin. When the amount of the hydroxyl group is within the above range, the hardening reaction of the soft magnetic film in the semi-hardened state becomes good, and deterioration can be suppressed.

The resin component preferably contains an acrylic resin in addition to the thermosetting resin. More preferably, an acrylic resin, an epoxy resin, and a phenol resin are used in combination. Further preferably, the resin component is composed only of an epoxy resin, a phenol resin, and an acrylic resin. When the resin component contains the resin, a soft magnetic film in a hardened state is produced by laminating a plurality of layers of a semi-hardened soft magnetic film, whereby a laminated interface can be obtained without unevenness and uniformity. A soft magnetic film with good characteristics.

The acrylic resin is, for example, acrylic acid obtained by polymerizing one or two or more kinds of alkyl (meth)acrylates having a linear or branched alkyl group as a monomer component and polymerizing the monomer component. It is a polymer or the like. Further, "(meth)acrylic acid (醯)" means "acrylic acid (醯) and/or methacrylic acid (醯)".

Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, a tert-butyl group, an isobutyl group, a pentyl group, an isopentyl group, a hexyl group, a heptyl group, a cyclohexyl group, and 2 -ethylhexyl, octyl, isooctyl, decyl, isodecyl, decyl, isodecyl, undecyl, lauryl, tridecyl, tetradecyl, stearyl, octadecyl An alkyl group such as an alkyl group or a dodecyl group having 1 to 20 carbon atoms. An alkyl group having 1 to 6 carbon atoms is preferred.

The acrylic polymer may also be a copolymer of an alkyl (meth)acrylate and another monomer.

Examples of the other monomer include glycidyl group-containing monomers such as glycidyl acrylate and glycidyl methacrylate, such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxy amyl acrylate, and itaconic acid. a carboxyl group-containing monomer such as maleic acid, fumaric acid or crotonic acid, for example, an acid anhydride monomer such as maleic anhydride or itaconic anhydride, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl methacrylate, (meth) acrylate Acid 4-hydroxybutyl ester, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate Or a hydroxyl group-containing monomer such as (4-hydroxymethylcyclohexyl)-methyl acrylate, such as styrenesulfonic acid, allylsulfonic acid, 2-(methyl)propenylamine-2-methylpropanesulfonic acid , (meth) acrylamide propyl sulfonic acid, sulfopropyl (meth) acrylate, sulfonic acid group-containing monomer such as (meth) propylene phthaloxy naphthalene sulfonic acid, 2-hydroxy propyl decyl phosphate A phosphate group-containing monomer such as an ester, such as a styrene monomer, acrylonitrile or the like.

Among these, a glycidyl group-containing monomer, a carboxyl group-containing monomer or a hydroxyl group-containing monomer can be preferably exemplified. When the acrylic resin is a copolymer of an alkyl (meth)acrylate and a monomer other than the above, that is, when the acrylic resin has a glycidyl group, a carboxyl group or a hydroxyl group, the heat resistance of the soft magnetic film Excellent.

In the case of a copolymer of an alkyl (meth) acrylate and another monomer, the compounding ratio (mass) of the other monomer is preferably 40% by mass or less based on the copolymer.

The weight average molecular weight of the acrylic resin is, for example, 1 × 10 ⁵ or more, preferably 3 × 10 ⁵ or more, and is, for example, also 1 × 10 ⁶ or less. By setting it as this range, it is excellent in the adhesiveness and heat resistance of a soft magnetic film. Further, the weight average molecular weight can be measured by gel permeation chromatography (GPC) using a standard polystyrene equivalent value.

The glass transition point (Tg) of the acrylic resin is, for example, -30 ° C or higher, preferably -20 ° C or higher, and is also, for example, 30 ° C or lower, preferably 15 ° C or lower. When it is more than the above lower limit, the soft magnetic film in a semi-hardened state is excellent in adhesion. On the other hand, when it is less than or equal to the above upper limit, the soft magnetic film is excellent in handleability. Furthermore, the glass transition point can be measured by a dynamic viscoelasticity measuring device (DMA (Dynamic Mechanical Analyzer), frequency 1 Hz, heating rate 10 ° C / min) to measure the maximum value of the loss tangent (tan δ) And get.

When the resin component contains an acrylic resin, the content ratio of the thermosetting resin in the resin component is, for example, 20% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, more preferably 65% by mass or more. Further, for example, it is 90% by mass or less, preferably 80% by mass or less, and more preferably 70% by mass or less. When the content ratio of the thermosetting resin is in the above range, in particular, when the thermosetting resin is contained (more than 50% by mass), the expansion of the resin due to the high temperature and the generation of the void of the soft magnetic film can be effectively suppressed. Therefore, the soft magnetic film is excellent in reflow resistance.

The content ratio of the acrylic resin in the resin component is, for example, 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, and for example, 80% by mass or less, preferably less than 50% by mass. More preferably, it is 40 mass% or less, More preferably, it is 35 mass% or less.

The content ratio of the resin component in the soft magnetic resin composition is, for example, 5% by mass or more, preferably 8% by mass or more, more preferably 10% by mass or more, and further, for example, 30% by mass or less, preferably 20% by mass. Hereinafter, it is more preferably 15% by mass or less. By setting it as the said range, it is excellent in the film-forming property and magnetic characteristics of a soft magnetic film.

In addition, the content ratio of the thermosetting resin (preferably a thermosetting resin containing an epoxy resin and a phenol resin) is 100 parts by mass, for example, 20 parts of the soft magnetic particle-excluding component other than the soft magnetic particles in the soft magnetic resin composition. The mass part or more is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, still more preferably 60 parts by mass or more, most preferably 65 parts by mass or more, and further, for example, 99 parts by mass or less, preferably 90%. It is more preferably 80 parts by mass or less, and most preferably 70 parts by mass or less. By setting it as the said range, the soft magnetic film is excellent in the reflow resistance.

More specifically, the soft magnetic particle-excluding component contains a component of a resin component, a thermosetting catalyst (described below) and an additive (described below) which are optionally added, and does not contain soft magnetic particles and a solvent.

The resin component may contain a thermoplastic resin other than a thermosetting resin or an acrylic resin.

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

The soft magnetic resin composition (further, a soft magnetic film) preferably contains a thermosetting catalyst.

The thermosetting catalyst is not limited as long as it is a catalyst for promoting the curing of the resin component by heating, and examples thereof include a salt having an imidazole skeleton, a salt having a triphenylphosphine structure, and triphenylboron. a salt of an alkane structure, a compound containing an amine group, and the like. A salt having an imidazole skeleton can be preferably exemplified.

Examples of the salt having an imidazole skeleton include 2-phenylimidazole (trade name: 2PZ), 2-ethyl-4-methylimidazole (trade name: 2E4MZ), and 2-methylimidazole (trade name: 2MZ). ), 2-undecylimidazole (trade name: C11Z), 2-phenyl-4,5-dihydroxymethylimidazole (trade name: 2PHZ-PW), 2,4-diamino-6-( 2'-Methylimidazolyl (1)') Ethyl An isocyanurate adduct (trade name: 2MAOK-PW), etc. (the above-mentioned trade names are all manufactured by Shikoku Chemicals Co., Ltd.). The heat-curing catalyst may be used singly or in combination of two or more.

Examples of the shape of the heat-curing catalyst include a spherical shape, an ellipsoid shape, and the like.

The blending ratio of the heat-hardening catalyst is, for example, 0.1 parts by mass or more, preferably 0.3 parts by mass or more, and further, for example, 5 parts by mass or less, preferably 3 parts by mass or less, based on 100 parts by mass of the resin component. By setting the blending ratio of the thermosetting catalyst within the above range, the soft magnetic film in the semi-hardened state can be heat-hardened at a relatively low temperature and for a short period of time, and the reflow resistance is excellent.

The soft magnetic resin composition (further, a soft magnetic film) may further contain other additives as needed. Examples of the additive include a dispersant, a crosslinking agent, and an inorganic filler. It is commercially available or known to the public.

The soft magnetic resin composition preferably contains a dispersing agent.

Examples of the dispersant include a polyether phosphate, a decane coupling agent, and a titanate coupling agent. A polyether phosphate ester is preferably exemplified. By providing the soft magnetic resin composition with a dispersant, particularly a polyether phosphate, the applicability of the soft magnetic resin composition can be improved, and the magnetic properties of the soft magnetic film can be further improved.

Examples of the polyether phosphates include polyoxyalkylene alkyl alkyl ether phosphates and polyoxyalkylene alkylphenyl ether phosphates. A polyoxyalkylene alkyl ether phosphate can be preferably exemplified.

The polyoxyalkylene alkyl ether phosphate has a form in which 1 to 3 alkyl-oxy-poly(alkylene oxide) groups are bonded to a phosphorus atom of a phosphate. In the alkyl-oxy-poly(alkylene oxide) group [that is, the polyoxyalkylene alkyl ether moiety], the number of repetitions of the alkoxy group as the poly(alkylene oxide) moiety is not particularly limited. For example, it can be appropriately selected from the range of 2 to 30 (preferably 3 to 20). The alkylene group having a poly(alkylene oxide) moiety is preferably an alkylene group having a carbon number of 2 to 4. Specific examples thereof include an ethyl group, a propyl group, an extended isopropyl group, a butyl group, an isobutyl group and the like. Further, the alkyl group is not particularly limited, and examples thereof include an alkyl group having 6 to 30 carbon atoms, and more preferably an alkyl group having 8 to 20 carbon atoms. Specifically, examples of the alkyl group include a mercapto group, an undecyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, and a heptadecyl group. Octadecyl and the like. Further, in the case where the polyoxyalkylene alkyl ether phosphate has a plurality of alkyl-oxy-poly(alkylene oxide) groups, the plurality of alkyl groups may be different or the same. Further, the polyether phosphate may also be a mixture with an amine or the like.

The acid value of the polyether phosphate is, for example, 10 or more, preferably 15 or more, and is, for example, 200 or less, preferably 150 or less. The acid value can be measured by a neutralization titration method or the like.

Examples of the decane coupling agent include 3-methacryloxypropyltrimethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, and the like.

The dispersing agent may be used singly or in combination of two or more.

Specific examples of the dispersing agent include the HIPLAAD series ("ED152", "ED153", "ED154", "ED118", "ED174", "ED251"), and the KBM series manufactured by Shin-Etsu Chemical Co., Ltd. "KBM303", "KBM503"), etc.

The content ratio of the dispersing agent is, for example, 0.1 part by mass or more, preferably 0.2 part by mass or more, based on 100 parts by mass of the soft magnetic particles. Further, for example, it is 5 parts by mass or less, preferably 2 parts by mass or less.

The soft magnetic resin composition can be prepared by mixing the above components in the above-mentioned content ratio.

The soft magnetic resin composition can be prepared by mixing the above components in the above-mentioned content ratio.

The soft magnetic film can be produced, for example, by a preparation step of preparing a soft magnetic resin composition solution by dissolving or dispersing the soft magnetic resin composition in a solvent; and a drying step by coating the release film A surface of the substrate is dried and dried to obtain a soft magnetic film in a semi-hardened state; and a hot pressing step of laminating a plurality of soft magnetic films in a semi-hardened state and hot pressing.

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

The solvent may, for example, be a ketone such as acetone or methyl ethyl ketone (MEK), or an ester such as ethyl acetate, or an ether such as propylene glycol monomethyl ether, for example, N,N-dimethylformamide or the like. An organic solvent such as guanamine. Further, examples of the solvent include water, for example, an aqueous solvent such as an alcohol such as methanol, ethanol, propanol or isopropanol.

The amount of the solid content component in the soft magnetic resin composition solution is, for example, 10% by mass or more, preferably 30% by mass or more, and further, for example, 90% by mass or less, preferably 70% by mass or less.

Next, the soft magnetic resin composition solution is applied to a release substrate (separator, core material, etc.) The surface is dried 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.

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 longer and 5 minutes or shorter.

Examples of the separator include a polyethylene terephthalate (PET) film, a polyethylene film, a polypropylene film, and paper. The surface of the separator is subjected to a release treatment by, for example, a fluorine-based release agent, an acrylic long-chain alkyl ester release agent, a polyoxymethylene release agent, or the like.

Examples of the core material include a plastic film (for example, a polyimide film, a polyester film, a polyethylene terephthalate film, a polyethylene naphthalate film, a polycarbonate film, etc.), and a metal film. (for example, aluminum foil, etc.), for example, a resin substrate reinforced by a glass fiber or a non-woven fabric made of plastic, a ruthenium substrate, a glass substrate, or the like.

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

Thereby, a soft magnetic film in a semi-hardened state is obtained.

The soft magnetic film is a soft magnetic thermosetting adhesive film having a semi-hardened state (B-stage state) at room temperature (specifically, 25 ° C) and having good adhesion.

The average thickness of the soft magnetic film (semi-hardened state) is, for example, 5 μm or more, preferably 50 μm or more, and is, for example, 500 μm or less, or preferably 250 μm or less.

Next, a soft magnetic film in a semi-hardened state obtained by a plurality of sheets is prepared, and a plurality of soft magnetic films are hot-pressed in the thickness direction by hot pressing (hot pressing step). Thereby, the soft magnetic film (further, the soft magnetic composition) in a semi-hardened state is heat-hardened. Further, the soft magnetic particles can be filled into the soft magnetic film at a high ratio to improve the magnetic properties.

The hot pressing can be carried out by using a known press, and examples thereof include a parallel plate press and the like.

The number of laminated layers of the soft magnetic film (semi-hardened state) is, for example, two or more layers, and is, for example, 20 or less, preferably 5 or less. Thereby, the soft magnetic properties can be adjusted to the desired thickness membrane.

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

The heating time is, for example, 0.1 hour or longer, preferably 0.2 hour or longer, and for example, 24 hours or shorter, preferably 2 hours or shorter.

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

Thereby, the soft magnetic film in a semi-hardened state can be heat-hardened to obtain a soft magnetic film in a hardened state (C-stage state).

The average thickness of the 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 tensile storage modulus E' _{23 at} 23 ° C is, for example, 8.0 × 10 ⁸ Pa or more, preferably 1.0 × 10 ⁹ Pa or more, more preferably 1.0 × 10 ¹⁰ Pa or more, and further, for example, 1.0 × 10 ²⁰ Pa. the following.

The tensile storage modulus E' _{200 at} 200 ° C is, for example, 1.0 × 10 ⁸ Pa or more, preferably 8.0 × 10 ⁸ Pa or more, more preferably 5.0 × 10 ⁹ Pa or more, and further, for example, 1.0 × 10 ²⁰ Pa. the following. Thereby, the reflow resistance of the soft magnetic film is further improved.

E _{'200 is} with respect to E' ₂₃ ratio of E _'200 / E' ₂₃ is 0.25 or more, preferably 0.40 or more, more preferably 0.42 or more, further preferably 0.45 or more, and, for example, 0.90 or less. Thereby, the soft magnetic film is excellent in reflow resistance.

Further, the tensile storage modulus (E' ₂₃ , E' ₂₀₀ ) was measured using a dynamic viscoelasticity measuring apparatus under the conditions of a temperature increase rate of 10 ° C / min and a frequency of 1 Hz.

The soft magnetic film is preferably such that the flat soft magnetic particles contained in the soft magnetic film are arranged along the two-dimensional in-plane direction of the soft magnetic film. In other words, the longitudinal direction of the flat soft magnetic particles (the direction orthogonal to the thickness direction) is aligned along the surface direction of the soft magnetic film. Thereby, the soft magnetic film fills the soft magnetic particles at a high ratio, and the magnetic properties are excellent. Also, to achieve soft magnetic Thin film formation.

The relative magnetic permeability (before the reflow step) of the soft magnetic film is, for example, 150 or more, preferably 160 or more, more preferably 180 or more, and for example, 500 or less.

The soft magnetic film can be, for example, a single layer structure composed of only a single layer of a soft magnetic film, a multilayer structure having a soft magnetic film on one side or a two-layer layer of the core material, or a single-sided or two-layer layer on the soft magnetic film. The shape of the multilayer structure of the separator.

Further, in the above-described embodiment, a plurality of soft magnetic films in a semi-hardened state are laminated and hot pressed. However, for example, one piece (single layer) of a soft magnetic film in a semi-hardened state may be subjected to hot pressing.

Further, in the above embodiment, the soft magnetic film in the semi-hardened state is hot-pressed, but hot pressing may not be performed. That is, the soft magnetic film can also be used directly in a semi-hardened state. Since the surface of the semi-hardened soft magnetic film has adhesiveness, it can be directly laminated on the circuit board without using an adhesive, for example. Thereafter, it may be heat-hardened as needed to form a soft magnetic film in a hardened state.

The soft magnetic film can be preferably used, for example, as a soft magnetic film (magnetic film) for laminating an antenna, a coil, or a circuit board on which the surface is formed. More specifically, it can be used for smart phones, computers, position detection devices, and the like.

In order to laminate a soft magnetic film on a circuit board, a method in which a soft magnetic film in a cured state is fixed to a circuit board via an adhesive layer, and a soft magnetic film in a semi-hardened state is directly attached to a circuit board, A method in which a soft magnetic film in a semi-hardened state is heat-hardened and fixed to a circuit board.

From the viewpoint of miniaturization of an electronic device without an adhesive layer, a method of directly bonding a soft magnetic film in a semi-hardened state to a circuit board and then heat-hardening the soft magnetic film can be preferably used.

Moreover, from the viewpoint of insulation, a method of fixing a soft magnetic film in a cured state to a circuit board via an adhesive layer is preferably exemplified.

The subsequent layer can be used by a person who is generally used as an adhesive layer of a circuit substrate, for example, It can be formed by applying an adhesive such as an epoxy-based adhesive, a polyimide-based adhesive, or an acrylic adhesive, and drying. The thickness of the subsequent layer is, for example, 10 to 100 μm.

Further, the tensile storage modulus E at 200 deg.] C of the soft magnetic film of the _'200 with respect to the tensile storage modulus E under the 23 ℃' ratio _{(E '200 / E' 23} ) 23 of 0.25 or more, even In the case where the soft magnetic film is subjected to the reflow treatment, the deterioration of the relative magnetic permeability of the soft magnetic film can also be suppressed. That is, it is excellent in reflow resistance. Thereby, even if the reflow process is performed on the mounted circuit board including the soft magnetic film, the soft magnetic film can surely exhibit excellent magnetic characteristics to the mounted circuit board.

The temperature in the reflow step is, for example, 200 ° C or higher, preferably 250 ° C or higher, and further, for example, 500 ° C or lower, preferably 300 ° C or lower.

The reflow storage time is, for example, 1 second or longer, preferably 5 seconds or longer, and is, for example, 10 minutes or shorter, preferably 5 minutes or shorter.

The relative magnetic permeability of the soft magnetic film after the reflow step is, for example, 150 or more, preferably 160 or more, more preferably 180 or more, and for example, 500 or less.

[Examples]

The present invention will be specifically described below by way of examples and comparative examples, but the present invention is not limited to any examples and comparative examples. The numerical values of the examples shown below can be replaced with the numerical values (i.e., the upper limit value or the lower limit value) described in the above embodiments.

Example 1

500 parts by mass of soft magnetic particles, 59 parts by mass of acrylate-based polymer, and bisphenol A-type epoxy resin ("Epikote 1004") 8 masses so that the soft magnetic particles are 50% by volume based on the soft magnetic resin composition. 4 parts by mass of bisphenol A type epoxy resin ("Epikote YL980"), 5 parts by mass of phenol aralkyl resin, and 2-phenyl-4,5-dihydroxymethylimidazole ("2PHZ-PW" thermosetting) 0.81 parts by mass of the catalyst (1.0 parts by mass based on 100 parts by mass of the resin component) and 2.5 parts by mass of the polyether phosphate (dispersant) (0.5 parts by mass based on 100 parts by mass of the soft magnetic particles) are mixed. This obtained a soft magnetic resin composition.

A soft magnetic resin composition solution having a solid content concentration of 43% by mass was prepared by dissolving the soft magnetic resin composition in methyl ethyl ketone.

The soft magnetic resin composition solution was applied onto a separator (having an average thickness of 50 μm) containing a polyethylene terephthalate film by polyfluorination-releasing treatment, followed by drying at 130 ° C for 2 minutes. Thereby, a soft magnetic film (only the average thickness of the soft magnetic film, 90 μm) in which the separator was laminated in a semi-hardened state was produced.

Next, the soft magnetic film was laminated in four layers and heat-hardened by hot pressing at 175 ° C for 30 minutes and 20 MPa to prepare a soft magnetic film in a cured state.

Examples 2 and 3

The soft magnetic resin composition was obtained from the materials and the blending ratios shown in Table 1. A soft magnetic film of the cured state of Examples 2 and 3 was produced in the same manner as in Example 1 except that the soft magnetic resin composition was used.

Comparative example 1 (soft magnetic film)

The soft magnetic resin composition was obtained by mixing 500 parts by mass of the soft magnetic particles and 106 parts by mass of the ethylene-vinyl acetate copolymer so that the soft magnetic particles were 40% by volume with respect to the soft magnetic resin composition.

The soft magnetic resin composition was dissolved in toluene to prepare a soft magnetic resin composition solution having a solid content concentration of 40% by mass.

The soft magnetic resin composition solution was applied onto a separator (having an average thickness of 50 μm) containing a polyethylene terephthalate film by polyfluorination-releasing treatment, followed by drying at 130 ° C for 2 minutes. Thereby, a soft magnetic film (only the average thickness of the soft magnetic film, 90 μm) in which the separator was laminated in a semi-hardened state was produced.

Next, the soft magnetic film was laminated in four layers and heat-hardened by hot pressing at 175 ° C for 30 minutes and 20 MPa to prepare a soft magnetic film of Comparative Example 1.

Comparative example 2

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

(Stretch storage modulus E' ₂₃ and E' ₂₀₀ measurement)

With respect to the soft magnetic films of the respective examples and comparative examples, dynamic viscoelasticity measurement was carried out based on the following conditions, and the tensile storage modulus E' _{23 at} 23 ° C and the tensile storage modulus E' at 200 ° C were respectively determined. ₂₀₀ .

Dynamic Viscoelasticity Measuring Device (MDA): trade name "RSAIII", manufactured by Rheometric Scientific

Mode: Stretch mode

Heating rate: 10 ° C / min

Frequency: 1Hz

Sample thickness: 90μm

Chuck spacing: 20mm

Strain: 0.1%

Measuring temperature range: 0 ° C ~ 210 ° C

The results and ratios (E' ₂₀₀ /E' ₂₃ ) are shown in Table 1.

(magnetic properties)

The relative magnetic permeability of the soft magnetic hot film of each of the examples and the comparative examples was measured by a single coil method (frequency: 1 MHz) using an Impedance Analyzer ("4294A" manufactured by Agilent Co., Ltd.). The results are shown in Table 1.

(resistance to reflow)

The soft magnetic film of each of the examples and the comparative examples was laminated on a circuit board, and the soft magnetic film laminated circuit board was passed through an IR (Infrared Ray) reflow furnace at 260 ° C for 10 seconds. Perform the reflow step.

Using an Impedance Analyzer (manufactured by Agilent, "4294A") The relative magnetic permeability of the soft magnetic film of the soft magnetic film laminated circuit substrate on which the reflow step was carried out was measured by a single coil method (frequency: 1 MHz). The results are shown in Table 1.

The numerical values in the respective components in the table indicate the parts by mass unless otherwise specified. In addition, the details of the abbreviations of the components in the table are described below.

. Fe-Si-Al alloy: trade name "SP-7", soft magnetic particles, flat shape, average particle size 65μm, manufactured by Meito

. Acrylate-based polymer: trade name "Pagoclone W-197CM", acrylate-based polymer containing ethyl acrylate-methyl methacrylate as main component, manufactured by Kokusai Industrial Co., Ltd.

. Bisphenol A type epoxy resin: trade name "Epikote 1004", epoxy equivalent 875~975g/eq, manufactured by JER

. Bisphenol A type epoxy resin: trade name "Epikote YL980", epoxy equivalent 180~190g/eq, manufactured by JER

. 4-functional aminoglycidyl epoxy resin: trade name "Tetrad-C", epoxy equivalent 105g/eq, manufactured by Mitsubishi Gas Chemical Industry Co., Ltd.

. Phenol aralkyl resin: trade name "Milex XLC-4L", hydroxyl equivalent 170g / eq, manufactured by Mitsui Chemicals Co., Ltd.

. 2-Phenyl-4,5-dihydroxymethylimidazole: thermosetting catalyst, trade name "Curezol 2PHZ-PW", manufactured by Shikoku Chemicals Co., Ltd.

. Polyether phosphate: dispersant, trade name "HIPLAAD ED152", manufactured by Nanben Chemical Company, acid value 20

. Ethylene-vinyl acetate copolymer: trade name "EV170", manufactured by Mitsui-Dupont Polychemical

Further, the invention is provided by the exemplified embodiments of the invention, but is merely illustrative and not to be construed as limiting. Variations of the invention as clarified by those skilled in the art are included in the scope of the following claims.

[Industrial availability]

The soft magnetic film of the present invention can be applied to various industrial products, for example, it can be used for a position detecting device such as a coordinate reading device.

Claims (6)

A soft magnetic film characterized in that it contains flat soft magnetic particles and has a tensile storage modulus E' ₂₀₀ at 200 ° C in a dynamic viscoelasticity measurement at a heating rate of 10 ° C/min and a frequency of 1 Hz. The ratio E' ₂₀₀ /E' ₂₃ to the tensile storage modulus E' ₂₃ at 23 ° C is 0.25 or more. The soft magnetic film of claim 1, wherein the tensile storage modulus E' ₂₀₀ at 200 ° C is 8.0 × 10 ⁸ Pa or more. The soft magnetic film of claim 1, which is formed of a soft magnetic resin composition containing an epoxy resin, a phenol resin, and an acrylic resin. The soft magnetic film according to claim 3, wherein the soft magnetic resin composition has a total content of the epoxy resin and the phenol resin of 20 parts by mass based on 100 parts by mass of the soft magnetic particle-excluding component other than the soft magnetic particles. More than the mass part and 99 parts by mass or less. The soft magnetic film according to claim 4, wherein a content ratio of the soft magnetic particles in the soft magnetic resin composition is 30% by volume or more and 70% by volume or less. The soft magnetic film of claim 1, which is in a hardened state.