Soft magnetic resin composition, soft magnetic film, inductor, and method for producing soft magnetic film

Abstract

This soft magnetic resin composition comprises a dispersion medium and a solid content including flat-shaped soft magnetic particles and a resin component. The viscosity (A) at a shear rate of 38.1 s-1 is at least 300 mPa·s. Furthermore, the ratio (A / C) of the viscosity (A) at a shear rate of 38.1 s-1 to the viscosity (C) at a shear rate of 191.5 s-1 is at least 1.7.

Description

Soft magnetic resin composition, soft magnetic film, inductor, and method for manufacturing soft magnetic film

[0001] The present disclosure relates to a soft magnetic resin composition, a soft magnetic film and an inductor using the soft magnetic resin composition, and a method for producing a soft magnetic film using the soft magnetic resin composition.

[0002] In recent years, the incorporation of wireless communication or wireless power transmission into electronic devices such as personal computers and smartphones has rapidly become widespread. To extend the wireless communication distance, improve efficiency, and reduce the size of electronic devices, soft magnetic films that converge magnetic flux are placed around the antennas and coils of electronic devices.

[0003] Such a soft magnetic film is formed from a soft magnetic resin composition containing flat soft magnetic particles, a resin component, and a dispersion medium (see, for example, Patent Document 1). Specifically, the soft magnetic film is produced by applying the soft magnetic resin composition onto a release liner using an applicator, drying the applied film, and then hot pressing it.

[0004] Japanese Patent Application Laid-Open No. 2015-092543

[0005] On the other hand, soft magnetic films are required to have excellent magnetic properties and to be capable of being produced stably and efficiently in continuous production.

[0006] However, when forming the soft magnetic film of Patent Document 1, the viscosity of the soft magnetic resin composition is insufficient, so that the soft magnetic particles in the soft magnetic resin composition tend to settle and become unevenly distributed, making it difficult to stably form a uniform soft magnetic film. Such a problem is likely to occur particularly when the soft magnetic resin composition is applied continuously at high speed to form the soft magnetic film.

[0007] The present disclosure provides a soft magnetic resin composition that enables stable, efficient, and continuous production of soft magnetic films with excellent magnetic properties, a soft magnetic film and inductor that use the soft magnetic resin composition, and a method for producing a soft magnetic film that uses the soft magnetic resin composition.

[0008] The present disclosure [1] provides a soft magnetic resin composition comprising a solid content including flat soft magnetic particles and a resin component, and a dispersion medium, and the composition is subjected to a shear rate of 38.1 s －１ The viscosity (A) at a shear rate of 191.5 s is 300 mPa·s or more. －１ Viscosity (C) at shear rate of 38.1 s －１ The soft magnetic resin composition has a viscosity (A) ratio (A / C) of 1.70 or more.

[0009] The present disclosure [2] includes the soft magnetic resin composition described in the above [1], in which the particle diameter (D90) at which the volume-based cumulative value from the small particle side of the flat soft magnetic particles is 90% is 80 μm or more and 130 μm or less.

[0010] The present disclosure [3] includes the soft magnetic resin composition according to the above [1] or [2], in which the particle diameter (D50) at which the volume-based cumulative value from the small particle side of the flat soft magnetic particles is 50% is 30 μm or more and 50 μm or less.

[0011] The present disclosure [4] includes the soft magnetic resin composition according to any one of [1] to [3] above, in which the particle diameter (D10) at which the volume-based cumulative value from the small particle size side of the flat soft magnetic particles is 10% is 5 μm or more.

[0012] The present disclosure [5] includes the soft magnetic resin composition according to any one of [1] to [4] above, wherein the solid content concentration of the soft magnetic resin composition is 11% by volume or more and 14% by volume or less.

[0013] The present disclosure [6] includes the soft magnetic resin composition according to any one of the above [1] to [5], wherein the resin component includes a thermosetting resin component and a thermoplastic resin component.

[0014] The present disclosure [7] includes the soft magnetic resin composition according to the above [6], in which the thermosetting resin component includes an epoxy resin and the thermoplastic resin component includes an acrylic resin.

[0015] The present disclosure [8] includes the soft magnetic resin composition according to the above [7], in which the thermosetting resin component further includes a curing agent and a curing accelerator.

[0016] The present disclosure [9] includes the soft magnetic resin composition according to any one of [1] to [8], wherein the content of the flat soft magnetic particles in the solid content of the soft magnetic resin composition is 45% by volume or more and 70% by volume or less.

[0017] The present disclosure

[10] includes the soft magnetic resin composition according to any one of [1] to [9] above, wherein the cured product of the soft magnetic resin composition has a magnetic permeability of 40 or more at a frequency of 10 MHz.

[0018] The present disclosure

[11] includes a soft magnetic film that is a cured product of the soft magnetic resin composition according to any one of [1] to

[10] above.

[0019] The present disclosure

[12] includes an inductor comprising the soft magnetic film and wiring described in

[11] above.

[0020] The present disclosure

[13] includes a method for producing a soft magnetic film, including a coating step of coating a substrate with the soft magnetic resin composition according to any one of the above [1] to

[10] at a coating speed of 5 m / min or more, a drying step of drying the dispersion medium contained in the soft magnetic resin composition coated on the substrate to obtain a semi-cured soft magnetic film, and a curing step of thermally curing the semi-cured soft magnetic film.

[0021] The present disclosure

[14] includes the method for producing a soft magnetic film according to the above

[13] , wherein in the coating step, the coating speed is increased continuously or stepwise until the coating speed becomes 5 m / min or more.

[0022] The present disclosure provides a soft magnetic resin composition comprising flat soft magnetic particles, a resin component, and a dispersion medium, the soft magnetic resin composition being resistant to a shear rate of 38.1 s －１ The viscosity (A) at a shear rate of 191.5 s is 300 mPa·s or more. －１ Viscosity (B) at a shear rate of 38.1 s －１ The ratio (A / B) of the viscosity (A) in the coating composition (A) to the viscosity (B) in the coating composition (A) is 1.7 or more. Therefore, the viscosity characteristics during continuous coating are excellent, and a soft magnetic film with excellent magnetic properties can be stably and efficiently produced continuously.

[0023] The soft magnetic film of the present disclosure is formed from the soft magnetic resin composition of the present disclosure, and therefore has excellent magnetic properties and can be produced stably, efficiently, and continuously.

[0024] The inductor of the present disclosure includes the soft magnetic film of the present disclosure, and therefore has excellent magnetic properties.

[0025] The method for producing a soft magnetic film according to the present disclosure includes a step of applying the soft magnetic resin composition according to the present disclosure to a substrate at a coating speed of 5 m / min or more, thereby enabling stable and efficient continuous production of the soft magnetic film.

[0026] FIG. 1 shows a cross-sectional view of an inductor according to an embodiment of the present disclosure. FIGS. 2A to 2C are diagrams illustrating the manufacturing process of the embodiment of the inductor shown in FIG. 1, with FIG. 2A showing a preparation process, FIG. 2B showing a placement process, and FIG. 2C showing a curing process. FIG. 3 shows a cross-sectional view of a magnetic wiring circuit board using a soft magnetic film according to the present disclosure. FIG. 4 shows the shear rate (s －１ 2 is a graph showing the relationship between the viscosity (mPa·s) and the viscosity (mPa·s).

[0027] 1. Soft Magnetic Resin Composition The soft magnetic resin composition of the present disclosure includes a solid content including flat soft magnetic particles and a resin component, and a dispersion medium. Note that the soft magnetic resin composition may also include other additives, as needed, as described below.

[0028] <Flat soft magnetic particles> Flat soft magnetic particles are soft magnetic particles having a flat (plate-like) shape. That is, flat soft magnetic particles are soft magnetic particles formed in a shape with a thin thickness and a wide surface. Note that soft magnetic particles are magnetic particles that have, for example, small coercive force, large magnetic permeability, and are easily magnetized when a magnetic field is applied, and easily return to their original state when the magnetic field is removed.

[0029] Such flat soft magnetic particles can be produced, for example, by powdering a soft magnetic material to obtain soft magnetic particles, and then processing the obtained soft magnetic particles into a flat shape (flattening process).

[0030] The soft magnetic material is not particularly limited, but examples thereof include magnetic stainless steel (Fe—Cr—Al—Si alloy), sendust (Fe—Si—Al alloy), permalloy (Fe—Ni alloy), 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, and ferrite. From the viewpoint of magnetic properties, the soft magnetic material is preferably an Fe—Si alloy.

[0031] The soft magnetic materials can be used alone or in combination.

[0032] The soft magnetic material can be powdered by, for example, gas atomization, water atomization, disk atomization, pulverization, etc. As the powdering method, gas atomization is preferably used.

[0033] Specifically, in the gas atomization method, first, a soft magnetic material is heated and melted to obtain a molten metal. Then, the obtained molten metal is flowed from a nozzle, and a gas (e.g., argon gas, nitrogen gas) is sprayed onto the molten metal. The molten metal is turned into droplets by the energy of the gas. These droplets are cooled as they fall, solidifying and forming powder, i.e., particles. In this way, the soft magnetic material is powdered to obtain soft magnetic particles.

[0034] In gas atomization, the molten metal is instantly transformed into droplets and cooled simultaneously, resulting in soft magnetic particles with a uniform fine structure. In addition, because droplets are formed continuously, the compositional differences between soft magnetic particles are extremely small.

[0035] The obtained soft magnetic particles may be classified before being flattened.

[0036] For example, an attritor or the like can be used to flatten the soft magnetic particles.

[0037] The processing conditions using the attritor are not particularly limited as long as they allow processing into flat soft magnetic particles having a specific particle diameter, i.e., particle size distribution, as described below.

[0038] The flattening of the soft magnetic particles may be performed by wet processing or dry processing, but is preferably performed by wet processing.

[0039] In the wet processing, it is preferable to use an organic solvent that can suppress oxidation during processing.

[0040] The organic solvent is not particularly limited as long as it can suppress oxidation during processing, and examples thereof include alcohol.

[0041] The amount of organic solvent added can be adjusted appropriately depending on the type of soft magnetic particles, etc.

[0042] The obtained flat soft magnetic particles may be heat-treated or classified as required.

[0043] The flattening ratio or flatness of the flat soft magnetic particles is, for example, 8 or more and 80 or less, preferably 15 or more and 65 or less.

[0044] The flatness of the flat soft magnetic particles is calculated, for example, as the aspect ratio obtained by dividing D50, which is the particle diameter at which the volume-based cumulative value from the small particle side of the flat soft magnetic particles described below is 50%, by the average thickness of the flat soft magnetic particles.

[0045] The particle diameter D90, which is the particle diameter at which the volume-based cumulative value from the small particle side of the flat soft magnetic particles is 90%, is, for example, 60 μm or more and 150 μm or less, preferably 70 μm or more and 140 μm or less, more preferably 80 μm or more and 130 μm or less, even more preferably 80 μm or more and 110 μm or less, and particularly preferably 80 μm or more and 100 μm or less.

[0046] When the particle diameter D90 of the flat soft magnetic particles is equal to or greater than the lower limit, the magnetic properties of the soft magnetic film are improved. When the particle diameter D90 of the flat soft magnetic particles is equal to or less than the upper limit, the settling of the flat soft magnetic particles in the soft magnetic resin composition is suppressed, and unevenness during coating of the soft magnetic resin composition can be suppressed.

[0047] The particle diameter D50, which is the particle diameter at which the volume-based cumulative value from the small particle side of the flat soft magnetic particles is 50%, is, for example, 20 μm or more and 100 μm or less, preferably 25 μm or more and 75 μm or less, more preferably 30 μm or more and 50 μm or less, even more preferably 35 μm or more and 50 μm or less, and particularly preferably 38 μm or more and 47 μm or less.

[0048] If the particle diameter D50 of the flat soft magnetic particles is within the above range, the magnetic properties of the soft magnetic film are improved.

[0049] D10, which is the particle diameter at which the volume-based cumulative value from the small particle side of the flat soft magnetic particles is 10%, is, for example, 5 μm or more and 50 μm or less, preferably 10 μm or more and 30 μm or less, more preferably 12 μm or more and 20 μm or less, and even more preferably 13 μm or more and 17 μm or less.

[0050] The particle diameter D10, which is the particle diameter at which the volume-based cumulative value from the small particle side of the flat soft magnetic particles is 10%, is, for example, 5 μm or more, preferably 10 μm or more, more preferably 12 μm or more, even more preferably 13 μm or more, and particularly preferably more than 13 μm, and is, for example, 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 17 μm or less.

[0051] If the particle diameter D10 of the flat soft magnetic particles is equal to or greater than the lower limit, the soft magnetic film will have excellent properties such as appearance, and furthermore, the magnetic properties of the soft magnetic film will be improved.

[0052] Flat soft magnetic particles having the above particle diameter, i.e., particle size distribution, can be obtained, for example, by adjusting the conditions for flattening spherical soft magnetic particles using an attritor or the like. Alternatively, the flat soft magnetic particles after flattening can be obtained by classifying them using a classifier such as a dry classifier. As mentioned above, the final particle size distribution (particle size distribution of the flat soft magnetic particles after flattening) can also be adjusted by classifying the soft magnetic particles before flattening as necessary.

[0053] Furthermore, in order to obtain flat soft magnetic particles with the above particle diameter, flat soft magnetic particles with two or more different particle diameters (particle size distribution) can be mixed.That is, flat soft magnetic particles can be used as flat soft magnetic particles with specific particle diameter alone, or can be used in combination with two or more flat soft magnetic particles with different particle diameters (particle size distribution).In addition, when using two or more flat soft magnetic particles with different particle diameters (particle size distribution), the particle diameter of each flat soft magnetic particle before mixing does not need to be within the above range, and it is sufficient to adjust the particle diameter of flat soft magnetic particles after mixing to be within the above range.

[0054] The particle diameters of the flat soft magnetic particles, i.e., D10, D50, and D90, can be measured, for example, using a laser diffraction particle size distribution analyzer (LS 13 320, manufactured by Beckman Coulter). Specifically, the particle size distribution of the magnetic powder can be created on a volume basis using the laser diffraction particle size distribution analyzer, and D10, D50, and D90 can be measured. The measurement sample can be prepared by dispersing flat soft magnetic particles in pure water using ultrasonic waves.

[0055] The coercive force of the flat soft magnetic particles is, for example, 10 A / m or more and 1000 A / m or less, preferably 50 A / m or more and 200 A / m or less.

[0056] The coercive force can be measured, for example, by a vibrating sample magnetometer.

[0057] The specific gravity of the flat soft magnetic particles is, for example, 5.0 or more and 8.5 or less, or preferably 6.0 or more and 8.0 or less.

[0058] The content (mass proportion) of flat soft magnetic particles in the solid content of the soft magnetic resin composition is, for example, 70 mass% or more and 95 mass% or less, preferably 80 mass% or more and 92 mass% or less, more preferably 85 mass% or more and 90 mass% or less, and even more preferably 87 mass% or more and 90 mass% or less.

[0059] The content (volume percentage) of flat soft magnetic particles in the solid content of the soft magnetic resin composition is, for example, 40 volume % or more and 80 volume % or less, preferably 45 volume % or more and 70 volume % or less, more preferably 50 volume % or more and 70 volume % or less, even more preferably 53 volume % or more and 60 volume % or less, and particularly preferably 55 volume % or more and 57 volume % or less.

[0060] When the content of the flat soft magnetic particles in the solid content of the soft magnetic resin composition is equal to or greater than the above lower limit, the soft magnetic film has excellent magnetic properties. When the content of the flat soft magnetic particles in the solid content of the soft magnetic resin composition is equal to or less than the above upper limit, the content of the resin component described below can be sufficiently ensured, and the soft magnetic film has excellent film-forming properties.

[0061] The volume ratio of each component, such as flat soft magnetic particles, is calculated based on the theoretical volume obtained by dividing the mass of each component by the specific gravity of that component (the same applies below). The specific gravity of each component can be obtained from a catalog value or by a known measurement method (for example, a specific gravity measurement method).

[0062] The solid content of the soft magnetic resin composition refers to the solid content including the flat soft magnetic particles and the resin component described below. If necessary, other additives described below may be included. When the soft magnetic resin composition does not include other additives, the solid content of the soft magnetic resin composition refers to the total amount of the flat soft magnetic particles and the resin component.

[0063] The content (mass proportion) of the flat soft magnetic particles in the soft magnetic resin composition is, for example, 20 mass% or more and 50 mass% or less, preferably 30 mass% or more and 45 mass% or less, more preferably 35 mass% or more and 40 mass% or less, and even more preferably 36 mass% or more and 40 mass% or less.

[0064] The content (volume percentage) of the flat soft magnetic particles in the soft magnetic resin composition is, for example, 3.0 volume % or more and 15.0 volume % or less, preferably 5.0 volume % or more and 10.0 volume % or less, more preferably 5.5 volume % or more and 8.0 volume % or less, and even more preferably 6.0 volume % or more and 8.0 volume % or less.

[0065] If the content ratio of the flat soft magnetic particles in the soft magnetic resin composition is equal to or greater than the above lower limit, the viscosity of the soft magnetic resin composition when left standing (viscosity at low shear rate) can be sufficiently ensured, and therefore, the sedimentation and uneven distribution of the flat soft magnetic particles can be suppressed. Furthermore, the flat soft magnetic particles can be highly packed, and the magnetic properties can be improved. Furthermore, if the content ratio of the flat soft magnetic particles in the soft magnetic resin composition is equal to or less than the above upper limit, when the soft magnetic resin composition is applied, the fluidity of the soft magnetic resin composition can be increased (the viscosity at high shear rate can be reduced), and therefore the soft magnetic resin composition can be applied stably and efficiently continuously.

[0066] <Resin Component> The resin component includes, for example, at least one of a thermosetting resin component and a thermoplastic resin component. The resin component preferably includes both a thermosetting resin component and a thermoplastic resin component. The resin component may also include additives as needed. Examples of the additives include the same additives as those described below.

[0067] If the resin component contains both a thermosetting resin component and a thermoplastic resin component, as will be described in detail later, when multiple soft magnetic films before they are fully cured are laminated to produce a single soft magnetic film, a soft magnetic film with a uniform, even laminate interface and good magnetic permeability can be obtained.

[0068] [Thermosetting Resin Component] The thermosetting resin component includes, for example, a thermosetting resin, a curing agent, and a curing accelerator.

[0069] Examples of thermosetting resins include epoxy resins. Examples of thermosetting resins include amino resins, unsaturated polyester resins, polyurethane resins, silicone resins, urea resins, melamine resins, thermosetting polyimide resins, and diallyl phthalate resins. Epoxy resins are preferred as thermosetting resins.

[0070] The thermosetting resins can be used alone or in combination of two or more kinds.

[0071] Examples of epoxy resins include bisphenol-type epoxy resins (e.g., bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, bisphenol S-type epoxy resins, brominated bisphenol A-type epoxy resins, hydrogenated bisphenol A-type epoxy resins, and bisphenol AF-type epoxy resins), phenol-type epoxy resins (e.g., phenol novolac-type epoxy resins and orthocresol novolac-type epoxy resins), biphenyl-type epoxy resins, naphthalene-type epoxy resins, fluorene-type epoxy resins, trishydroxyphenylmethane-type epoxy resins, tetraphenylolethane-type epoxy resins, hydantoin-type epoxy resins, trisglycidyl isocyanurate-type epoxy resins, and glycidylamine-type epoxy resins. Phenol-type epoxy resins are preferred, and orthocresol novolac-type epoxy resins are more preferred.

[0072] The epoxy resins can be used alone or in combination of two or more kinds.

[0073] If the thermosetting resin is an epoxy resin, it has excellent reactivity with a curing agent (for example, a phenolic resin) described later, and as a result, the soft magnetic film has excellent heat resistance and magnetic permeability.

[0074] The epoxy equivalent of the epoxy resin is, for example, 50 g / eq. or more and 300 g / eq. or less, preferably 100 g / eq. or more and 250 g / eq. or less.

[0075] The density of the epoxy resin is, for example, 0.8 g / cm ３ Above, 1.5g / cm ３ Preferably, 1.0 g / cm or less ３ Above, 1.3g / cm ３ The following is the result.

[0076] The content of the thermosetting resin in the resin component is, for example, 10% by mass or more and 50% by mass or less, preferably 15% by mass or more and 40% by mass or less, more preferably 20% by mass or more and 35% by mass or less, and even more preferably 25% by mass or more and 30% by mass or less.

[0077] An example of the curing agent is a phenolic resin, which is used as a curing agent for epoxy resins, for example.

[0078] Examples of phenolic resins include novolac-type phenolic resins (e.g., phenol novolac resin, phenol aralkyl resin, cresol novolac resin, tert-butylphenol novolac resin, nonylphenol novolac resin, etc.) and resol-type phenolic resins (e.g., polyoxystyrene such as polyparaoxystyrene, etc.). Preferred phenolic resins include novolac-type phenolic resins, and more preferred phenol aralkyl resins. Specifically, biphenylene aralkyl phenolic resins are even more preferred phenolic resins.

[0079] The phenolic resins can be used alone or in combination of two or more kinds.

[0080] If the hardener is a phenol resin, the heat resistance of the soft magnetic film can be improved when it is used in an inductor or a circuit board.

[0081] The hydroxyl group equivalent of the phenolic resin is, for example, 50 g / eq. or more and 300 g / eq. or less, preferably 100 g / eq. or more and 250 g / eq. or less.

[0082] The density of phenolic resin is, for example, 0.8 g / cm ３ Above, 1.5g / cm ３ Preferably, 1.0 g / cm or less ３ Above, 1.3g / cm ３ The following is the result.

[0083] The content of the curing agent in the resin component is, for example, 10% by mass or more and 50% by mass or less, preferably 15% by mass or more and 40% by mass or less, more preferably 20% by mass or more and 35% by mass or less, and even more preferably 25% by mass or more and 30% by mass or less.

[0084] Examples of the curing accelerator include catalysts that accelerate the curing of thermosetting resins by heating.

[0085] Examples of the curing accelerator include imidazole compounds, triphenylphosphine compounds, triphenylborane compounds, and amino group-containing compounds, and preferably imidazole compounds.

[0086] Examples of the imidazole compound include 2-phenylimidazole (trade name "2PZ"), 2-ethyl-4-methylimidazole (trade name "2E4MZ"), 2-methylimidazole (trade name "2MZ"), 2-undecylimidazole (trade name "C11Z"), 2-phenyl-4,5-dihydroxymethylimidazole (trade name "2-PHZ"), 2-phenyl-1H-imidazole 4,5-dimethanol (trade name "2PHZ-PW"), and 2,4-diamino-6-(2'-methylimidazolyl(1)')ethyl-s-triazine isocyanuric acid adduct (trade name "2MAOK-PW"), and preferably 2-phenyl-1H-imidazole 4,5-dimethanol (all of the above trade names are manufactured by Shikoku Chemical Industry Co., Ltd.).

[0087] The curing accelerators can be used alone or in combination of two or more kinds.

[0088] The density of the curing accelerator is, for example, 1.0 g / cm ３ Above, 1.8g / cm ３ Preferably, 1.2 g / cm or less ３ Above, 1.5g / cm ３ The following is the result.

[0089] The content of the curing accelerator in the resin component is, for example, 0.1 mass% or more and 5.0 mass% or less, preferably 0.3 mass% or more and 3.0 mass% or less, more preferably 0.5 mass% or more and 2.0 mass% or less, and even more preferably 0.7 mass% or more and 1.5 mass% or less.

[0090] When the content of the curing accelerator in the resin component is equal to or less than the upper limit, the long-term storage stability of the soft magnetic resin composition at room temperature can be improved. On the other hand, when the content of the curing accelerator is equal to or more than the lower limit, the soft magnetic film before being completely cured can be heat-cured at a low temperature in a short time, and the soft magnetic film can be produced efficiently.

[0091] The content (mass proportion) of the thermosetting resin component in the resin component is, for example, 25 mass% or more and 90 mass% or less, preferably 35 mass% or more and 80 mass% or less, more preferably 45 mass% or more and 70 mass% or less, and even more preferably 50 mass% or more and 60 mass% or less.

[0092] The content (volume percentage) of the thermosetting resin component in the resin component is, for example, 25 vol% or more and 85 vol% or less, preferably 35 vol% or more and 75 vol% or less, more preferably 45 vol% or more and 65 vol% or less, and even more preferably 50 vol% or more and 55 vol% or less.

[0093] [Thermoplastic Resin Component] The thermoplastic resin component includes, for example, a thermoplastic resin, and is preferably made of a thermoplastic resin.

[0094] Examples of thermoplastic resins include acrylic resins, natural rubber, butyl rubber, isoprene rubber, chloroprene rubber, ethylene-vinyl acetate copolymers, polybutadiene resins, polycarbonate resins, thermoplastic polyimide resins, polyamide resins (e.g., 6-nylon, 6,6-nylon, etc.), phenoxy resins, saturated polyester resins (e.g., PET, PBT, etc.), polyamideimide resins, and fluororesins, and preferably, acrylic resins.

[0095] The thermoplastic resins can be used alone or in combination of two or more kinds.

[0096] Examples of acrylic resins include acrylic ester-based polymers obtained by polymerizing one or more (meth)acrylic acid alkyl esters having a linear or branched alkyl group as monomer components. Note that "(meth)acrylic" refers to "acrylic and / or methacrylic."

[0097] The weight average molecular weight of the acrylic resin is, for example, 1×10 ５ or more, preferably 3 × 10 ５ or more, for example, 1×10 ６ The following is the result.

[0098] If the weight average molecular weight of the acrylic resin is within the above range, the adhesiveness and heat resistance of the soft magnetic film will be excellent.

[0099] The weight average molecular weight is measured by gel permeation chromatography (GPC) using a standard polystyrene equivalent value.

[0100] The glass transition point can be determined from the maximum value of the loss tangent (tan δ) measured using a dynamic viscoelasticity measuring device (DMA, frequency 1 Hz, temperature rise rate 10° C. / min).

[0101] The density of the thermoplastic resin is, for example, 0.5 g / cm ３ Above, 1.5g / cm ３ Preferably, 0.8 g / cm or less ３ Above, 1.2g / cm ３ The following is the result.

[0102] The content (mass proportion) of the thermoplastic resin component in the resin component is, for example, 20 mass% or more and 75 mass% or less, preferably 30 mass% or more and 65 mass% or less, more preferably 35 mass% or more and 55 mass% or less, and even more preferably 40 mass% or more and 50 mass% or less.

[0103] The content (volume percentage) of the thermoplastic resin component in the resin component is, for example, 25 vol% or more and 80 vol% or less, preferably 35 vol% or more and 70 vol% or less, more preferably 40 vol% or more and 60 vol% or less, and even more preferably 45 vol% or more and 50 vol% or less.

[0104] When the content ratio of the thermoplastic resin component in the resin component is within the above range, the film-forming property of the soft magnetic resin composition and the adhesiveness of the soft magnetic film before complete curing are excellent.

[0105] The content (mass proportion) of the resin component in the solid content of the soft magnetic resin composition is, for example, 3 mass% or more and 30 mass% or less, preferably 5 mass% or more and 20 mass% or less, and more preferably 8 mass% or more and 15 mass% or less.

[0106] The content (volume percentage) of the resin component in the solid content of the soft magnetic resin composition is, for example, 20 volume % or more and 70 volume % or less, preferably 30 volume % or more and 60 volume % or less, more preferably 35 volume % or more and 50 volume % or less, and even more preferably 40 volume % or more and 50 volume % or less.

[0107] When the content of the resin component in the solid content of the soft magnetic resin composition is equal to or greater than the above lower limit, the soft magnetic film has excellent film-forming properties. When the content of the resin component in the solid content of the soft magnetic resin composition is equal to or less than the above upper limit, the content of the flat soft magnetic particles can be ensured, and the soft magnetic film has excellent magnetic properties.

[0108] The concentration (mass proportion) of the resin component in the soft magnetic resin composition is, for example, 2.0 mass% or more and 10.0 mass% or less, preferably 3.0 mass% or more and 8.0 mass% or less, more preferably 4.0 mass% or more and 5.0 mass% or less, and even more preferably 4.3 mass% or more and 5.0 mass% or less.

[0109] The concentration (volume ratio) of the resin component in the soft magnetic resin composition is, for example, 2.0 volume % or more and 10.0 volume % or less, preferably 3.5 volume % or more and 8.0 volume % or less, more preferably 4.5 volume % or more and 6.0 volume % or less, and even more preferably 4.8 volume % or more and 6.0 volume % or less.

[0110] If the concentration of the resin component in the soft magnetic resin composition is equal to or greater than the lower limit, the viscosity of the soft magnetic resin composition when left standing (viscosity at low shear rates) can be sufficiently ensured, thereby suppressing the settling and uneven distribution of the flat soft magnetic particles. Also, if the concentration of the resin component in the soft magnetic resin composition is equal to or less than the upper limit, the fluidity of the soft magnetic resin composition can be increased (viscosity at high shear rates can be reduced) when the soft magnetic resin composition is applied, thereby enabling stable and efficient continuous application of the soft magnetic resin composition.

[0111] <Dispersion Medium> In the soft magnetic resin composition, the flat soft magnetic particles and the resin component are dispersed in a dispersion medium.

[0112] Examples of the dispersion medium include organic solvents such as ketones such as acetone and methyl ethyl ketone (MEK), esters such as ethyl acetate, amides such as N,N-dimethylformamide, ethers such as propylene glycol monomethyl ether, and alcohols such as methanol, ethanol, propanol, and isopropanol. Examples of the dispersion medium include aqueous solvents (e.g., water). Ketones are preferred as the dispersion medium, and methyl ethyl ketone is more preferred.

[0113] The solid content concentration (mass proportion) of the soft magnetic resin composition is, for example, 20 mass% or more and 70 mass% or less, preferably 30 mass% or more and 60 mass% or less, more preferably 35 mass% or more and 50 mass% or less, and even more preferably 40 mass% or more and 45 mass% or less.

[0114] The solid content concentration (volume proportion) of the soft magnetic resin composition is, for example, 5 vol% or more and 50 vol% or less, preferably 5 vol% or more and 30 vol% or less, more preferably 8 vol% or more and 20 vol% or less, even more preferably 10 vol% or more and 15 vol% or less, and particularly preferably 11 vol% or more and 14 vol% or less.

[0115] If the solid content concentration of the soft magnetic resin composition is equal to or higher than the lower limit, the viscosity of the soft magnetic resin composition when left standing (viscosity at low shear rates) can be sufficiently ensured, thereby suppressing the sedimentation and uneven distribution of the flat soft magnetic particles. Also, if the solid content concentration of the soft magnetic resin composition is equal to or lower than the upper limit, the fluidity of the flat soft magnetic particles can be increased (viscosity at high shear rates can be reduced) when the soft magnetic resin composition is applied, thereby enabling the soft magnetic resin composition to be applied stably and efficiently continuously.

[0116] The soft magnetic resin composition may also contain other additives.

[0117] Examples of other additives include commercially available or known crosslinking agents, inorganic fillers, and the like.

[0118] The soft magnetic resin composition is prepared by mixing the above-mentioned flat soft magnetic particles, the resin component, and, if necessary, other additives in the above-mentioned ratio, and further dispersing the mixture in the above-mentioned dispersion medium.

[0119] Shear rate 38.1s －１ The viscosity (A) of the soft magnetic resin composition is 300 mPa·s or more, preferably 350 mPa·s or more, more preferably 400 mPa·s or more, even more preferably 420 mPa·s or more, particularly preferably 450 mPa·s or more, and for example, 1000 mPa·s or less, preferably 900 mPa·s or less, more preferably 800 mPa·s or less, even more preferably 750 mPa·s or less, particularly preferably 700 mPa·s or less. －１ The viscosity (A) of the soft magnetic resin composition is, for example, 300 mPa·s or more and 1000 mPa·s or less, preferably 350 mPa·s or more and 900 mPa·s or less, more preferably 400 mPa·s or more and 800 mPa·s or less, and even more preferably 420 mPa·s or more and 750 mPa·s or less.

[0120] Shear rate 38.1s －１ When the viscosity (A) of the soft magnetic resin composition is equal to or higher than the lower limit, sedimentation and uneven distribution of the flat soft magnetic particles can be suppressed. －１ When the viscosity (A) of the soft magnetic resin composition is equal to or less than the upper limit, the soft magnetic resin composition has excellent handleability.

[0121] Shear rate 76.6s －１ The viscosity (B) of the soft magnetic resin composition is 200 mPa·s or more and 800 mPa·s or less, preferably 250 mPa·s or more and 700 mPa·s or less, more preferably 280 mPa·s or more and 600 mPa·s or less, and even more preferably 300 mPa·s or more and 550 mPa·s or less.

[0122] Shear rate 191.5s －１The viscosity (C) of the soft magnetic resin composition is 150 mPa·s or more and 500 mPa·s or less, preferably 180 mPa·s or more and 400 mPa·s or less, and more preferably 200 mPa·s or more and 350 mPa·s or less.

[0123] Shear rate 383s －１ The viscosity (D) of the soft magnetic resin composition is 100 mPa·s or more and 400 mPa·s or less, preferably 120 mPa·s or more and 300 mPa·s or less, and more preferably 140 mPa·s or more and 250 mPa·s or less.

[0124] Shear rate 383s －１ In the above, if the viscosity (D) of the soft magnetic resin composition is equal to or higher than the lower limit, when the soft magnetic resin composition is applied, it is possible to prevent the flat soft magnetic particles from settling in the soft magnetic resin composition, and therefore the soft magnetic resin composition can be applied stably. －１ When the viscosity (D) of the soft magnetic resin composition is equal to or less than the above upper limit, the fluidity of the flat soft magnetic particles can be increased when the soft magnetic resin composition is applied, and therefore the soft magnetic resin composition can be applied stably and efficiently continuously.

[0125] In the following, the shear rate is 76.6 s －１ , 191.5s －１ , and 383s －１ The shear rate for each viscosity (B to D) of the soft magnetic resin composition is 38.1 s －１ The ratios of the viscosities (A) of the soft magnetic resin compositions in the above formulas are denoted as A / B, A / C, and A / D, respectively.

[0126] A / B is, for example, 1.20 or more and 2.00 or less, preferably 1.25 or more and 1.80 or less, and more preferably 1.25 or more and 1.40 or less.

[0127] A / C is 1.70 or more, preferably 1.75 or more, more preferably 1.80 or more, even more preferably 1.85 or more, particularly preferably 2.00 or more, and for example, 3.00 or less, preferably 2.50 or less, more preferably 2.30 or less, even more preferably 2.10 or less. Also, A / C is, for example, 1.70 or more and 3.00 or less, preferably 1.75 or more and 2.50 or less, more preferably 1.80 or more and 2.30 or less, even more preferably 1.85 or more and 2.10 or less.

[0128] When A / C is equal to or greater than the above lower limit, it is possible to suppress the settling and uneven distribution of the flat soft magnetic particles, and further, when coating the soft magnetic resin composition, it is possible to increase the fluidity of the flat soft magnetic particles, thereby enabling the soft magnetic resin composition to be continuously coated stably and efficiently.

[0129] A / D is, for example, 2.00 or more and 5.00 or less, preferably 2.30 or more and 4.00 or less, more preferably 2.50 or more and 3.50 or less, even more preferably 2.55 or more and 3.30 or less, and particularly preferably 2.55 or more and 3.10 or less.

[0130] The viscosity can be determined by the method described in JIS Z 8803 and ISO 3219 (JIS K 7117-2). Specifically, it can be measured using a cone-and-plate rotational viscometer. A cone-and-plate rotational viscometer is a viscometer described in JIS Z 8803 and ISO 3219 (JIS K 7117-2), and the liquid-contacting part consists of a cone rotor and a plate. The sample is filled between the cone and the plate.

[0131] Specifically, the viscosity can be determined by the method described in the examples below.

[0132] The shear rate is also commonly called the shear rate, and in the above-mentioned cone-and-plate rotational viscometer, it can be calculated by the following relationship between the shear rate (D) and the rotational speed (N). However, the cone angle (φ) differs depending on the measuring device. D = 2πN / 60φ D: shear rate (s －１ ) N: Rotational speed of the conical rotor (rpm) φ: Cone angle

[0133] 2. Soft Magnetic Film The soft magnetic film of the present disclosure is formed, for example, by thermally curing a soft magnetic resin composition. In other words, the soft magnetic film is a cured product of the soft magnetic resin composition.

[0134] The soft magnetic film is, for example, in a fully cured state.

[0135] The term "completely cured" refers to a state in which no heat is generated due to the curing reaction as measured by differential scanning calorimetry, for example.

[0136] The soft magnetic film is, for example, in the form of a film (including a sheet).

[0137] The thickness of the soft magnetic film is, for example, 5 μm or more and 500 μm or less, or preferably 50 μm or more and 250 μm or less.

[0138] The volume proportion (excluding voids) of flat soft magnetic particles in the soft magnetic film is, for example, 40 volume % or more and 80 volume % or less, preferably 45 volume % or more and 70 volume % or less, more preferably 50 volume % or more and 60 volume % or less, and even more preferably 53 volume % or more and 57 volume % or less.

[0139] If the volume ratio of the flat soft magnetic particles in the soft magnetic film is within the above range, the soft magnetic film will have excellent magnetic permeability.

[0140] The volume ratio of the flat soft magnetic particles can be measured by, for example, Archimedes' method.

[0141] For example, the soft magnetic film contains flat soft magnetic particles dispersed in the two-dimensional in-plane direction of the soft magnetic film. That is, the longitudinal direction of the flat soft magnetic particles (the direction perpendicular to the thickness direction) is oriented along the plane direction of the soft magnetic film. This provides the soft magnetic film with even better magnetic properties.

[0142] The soft magnetic film (cured product of the soft magnetic resin composition) has a magnetic permeability at a frequency of 10 MHz of, for example, 40 or more, preferably 45 or more, more preferably 47 or more, and even more preferably 49 or more.

[0143] The magnetic permeability at a frequency of 10 MHz can be determined by measuring the impedance at 10 MHz using, for example, an impedance analyzer (E4991B Impedance Analyzer, manufactured by KEYSIGHT).

[0144] The soft magnetic film can be used, for example, as a single-layer structure consisting of only a single layer of soft magnetic film, a multilayer structure in which a soft magnetic film is laminated on one or both sides of a core material, or a multilayer structure in which a release liner is laminated on one or both sides of a soft magnetic film.

[0145] <Method for producing soft magnetic film (method for using soft magnetic resin composition)> The method for producing a soft magnetic film of the present disclosure includes, for example, a coating step of continuously coating a substrate with the soft magnetic resin composition at a coating speed of 5 m / min or more, a drying step of drying the dispersion medium contained in the soft magnetic resin composition coated on the substrate to obtain a soft magnetic film before being completely cured, and a curing step of thermally curing the soft magnetic film before being completely cured.

[0146] (Coating Step) In the coating step, the soft magnetic resin composition is continuously coated onto the surface of the substrate at a coating speed of 5 m / min or more.

[0147] Examples of the substrate include a release liner and a core material.

[0148] Examples of release liners include polyethylene terephthalate (PET) film, polyethylene film, polypropylene film, and paper, with PET film being preferred. The surface of the release liner is preferably release-treated with a fluorine-based release agent, a long-chain alkyl acrylate-based release agent, a silicone-based release agent, or the like.

[0149] Examples of core materials include plastic films (e.g., polyimide films, polyester films, polyethylene terephthalate films, polyethylene naphthalate films, and polycarbonate films), metal films (e.g., aluminum foil), glass substrates, silicon substrates, and resin substrates reinforced with glass fibers or plastic nonwoven fibers.

[0150] The average thickness of the substrate is, for example, 1 μm or more and 500 μm or less.

[0151] The coating method is not particularly limited as long as it is a method that allows continuous coating, and is preferably a coating method that is suitable for mass production as long-length coating.Specific examples of the coating method include coating using a roll coater, and particularly coating using a comma head coater.

[0152] The coating gap is, for example, 100 μm or more and 1000 μm or less, preferably 150 μm or more and 800 μm or less, more preferably 200 μm or more and 700 μm or less, even more preferably 250 μm or more and 600 μm or less, and particularly preferably 300 μm or more and 500 μm or less.

[0153] The coating gap is the distance between the coating surface of the substrate and the knife roll when a comma head coater is used. The shear rate can be expressed as the ratio of the coating gap to the coating speed. Therefore, when coating at the same coating speed, a smaller coating gap imparts a higher shear rate to the soft magnetic resin composition.

[0154] If the coating gap is made too small, depending on the particle diameter of the flat soft magnetic particles contained in the soft magnetic resin composition, the particles may get caught in the coating gap, causing coating streaks. In other words, if the coating gap is equal to or greater than the above lower limit, it is possible to ensure the shear rate while suppressing coating streaks caused by particle catches.

[0155] The coating speed is, for example, 5 m / min or more and 50 m / min or less, preferably 6 m / min or more and 50 m / min or less, more preferably 7 m / min or more and 30 m / min or less, and even more preferably 8 m / min or more and 20 m / min or less.

[0156] As described above, when the coating gap is constant, a high shear rate requires a high coating speed. However, if the coating speed is too high, the drying oven must be long depending on the drying time in the subsequent drying step, resulting in a large-scale device. In other words, if the coating speed is equal to or less than the upper limit, the shear rate can be secured while saving space in the device.

[0157] The above coating speed indicates the coating speed when the soft magnetic resin composition is stably coated. In other words, this does not apply to the start and end of the coating process.

[0158] Specifically, at the start of the coating process, it is preferable to increase the coating speed continuously or stepwise until the coating speed reaches 5 m / min or more.

[0159] At the start of the coating process, increasing the coating speed continuously or stepwise can prevent coating unevenness from occurring at the edges. More specifically, at the start of coating, gradually increasing the coating speed continuously or stepwise can prevent a sudden change in the viscosity of the soft magnetic resin composition, thereby preventing coating unevenness due to liquid depletion.

[0160] It is also preferable to reduce the coating speed continuously or stepwise at the end of the coating process.

[0161] (Drying Step) In the drying step, the dispersion medium contained in the soft magnetic resin composition applied to the substrate is dried to obtain a soft magnetic film before being completely cured.

[0162] The drying temperature is, for example, 70°C or higher and 160°C or lower.

[0163] The drying time is, for example, 1 minute or more and 5 minutes or less.

[0164] This allows the dispersion medium contained in the applied soft magnetic resin composition to dry, and a film before being completely cured is obtained.

[0165] This soft magnetic film before complete curing is a soft magnetic film in a state before complete curing at room temperature (e.g., 25° C.) and is a soft magnetic adhesive film with good adhesiveness. Note that the soft magnetic film before complete curing is in a state between a soft magnetic resin composition in an uncured state and a soft magnetic film in a completely cured state at room temperature (e.g., 25° C.), and is in a state in which curing has progressed slightly.

[0166] The average film thickness of the soft magnetic film before complete curing is, for example, 5 μm or more and 500 μm or less, preferably 5 μm or more and 300 μm or less, more preferably 5 μm or more and 200 μm or less, even more preferably 50 μm or more and 150 μm or less, and particularly preferably 50 μm or more and 100 μm or less.

[0167] (Curing Step) In the curing step, the soft magnetic film before being completely cured is thermally cured to obtain a soft magnetic film (a soft magnetic film in a completely cured state).

[0168] Specifically, a plurality of pre-cured soft magnetic films obtained in the drying process are prepared, and the pre-cured soft magnetic films are heat-pressed in the thickness direction. This hardens the pre-cured soft magnetic films to obtain a soft magnetic film. In other words, the soft magnetic film is a soft magnetic film in a fully cured state.

[0169] Furthermore, the above-described heat pressing is not limited to a mode in which only the soft magnetic film before complete curing is heat pressed. Specifically, as will be described in detail later, the soft magnetic film before complete curing and the wiring can also be heat pressed together. This makes it possible to obtain an inductor including the soft magnetic film and the wiring while curing the soft magnetic film before complete curing.

[0170] The heat pressing can be carried out using a known press, for example, a parallel plate press.

[0171] The number of semi-cured soft magnetic films to be laminated can be adjusted depending on the desired film thickness of the soft magnetic film, and is, for example, 2 or more and 20 or less, preferably 2 or more and 5 or less.

[0172] The temperature of the heat press is, for example, 80°C or more and 200°C or less, or preferably 100°C or more and 175°C or less.

[0173] The heat pressing time is, for example, 0.1 hour or more and 24 hours or less, preferably 0.2 hour or more and 3 hours or less, and more preferably 0.2 hour or more and 2 hours or less.

[0174] The pressure of the heat press is, for example, 10 MPa or more and 500 MPa or less, or preferably 20 MPa or more and 200 MPa or less.

[0175] This makes it possible to further improve the magnetic permeability of the flat soft magnetic particles in the soft magnetic film and to further reduce the thickness of the soft magnetic film.

[0176] This results in a fully cured soft magnetic film.

[0177] In the above-described method for producing a soft magnetic film, multiple soft magnetic films before being completely cured are stacked and heat-pressed, but for example, a single soft magnetic film (single layer) before being completely cured may also be heat-pressed.

[0178] Such a soft magnetic film can be used, for example, in an inductor or a magnetic wiring circuit board.

[0179] 3. Inductor One embodiment of the inductor of the present disclosure will be described with reference to FIGS.

[0180] The inductor 10 includes, for example, a soft magnetic film 1 and a wiring 2. Specifically, as shown in FIG. 1 , the inductor 10 includes, for example, a wiring 2 and a soft magnetic film 1 that covers the entire outer peripheral surface of the wiring 2.

[0181] The soft magnetic film 1 includes a resin component 3 and flat soft magnetic particles 4. The flat soft magnetic particles 4 are dispersed, for example, in a two-dimensional in-plane direction of the soft magnetic film 1. The soft magnetic resin composition may include additives other than the resin component 3 and the flat soft magnetic particles 4, but these additives are not shown.

[0182] The inductor may include a single or multiple wirings 2. When the inductor includes multiple wirings 2, one wiring 2 and another wiring 2 adjacent to the one wiring 2 in the width direction (first direction) perpendicular to the thickness direction are arranged at an interval in the width direction (first direction).

[0183] The wiring 2 extends longitudinally in a second direction perpendicular to both the thickness direction and the width direction, and its shape in plan view is not particularly limited. Examples of the shape of the wiring 2 in plan view include a generally straight shape in plan view and a generally U-shaped shape in plan view.

[0184] The cross-sectional shape of the wiring 2 is not particularly limited, and examples thereof include a generally circular cross-sectional shape and a generally rectangular cross-sectional shape. A preferred cross-sectional shape of the wiring 2 is a generally circular cross-sectional shape as shown in FIG.

[0185] The wiring 2 includes, for example, a conductor 5 and an insulating layer 6 covering the conductor 5 .

[0186] The conductor wire 5 extends elongately in the second direction, and has a shape in plan view similar to that of the wiring 2. Specifically, examples of the shape of the conductor wire 5 in plan view include a generally straight shape and a generally U-shape in plan view.

[0187] The cross-sectional shape of the conductor wire 5 is the same as that of the above-described wiring 2. The conductor wire 5 preferably has a generally circular cross-sectional shape that shares a central axis with the wiring 2.

[0188] The material of the conductor wire 5 is a metal conductor such as copper, silver, gold, aluminum, nickel, or an alloy thereof, preferably copper. The conductor wire 5 may have a single-layer structure or a multi-layer structure in which the surface of a core conductor (e.g., copper) is plated with nickel or the like.

[0189] The radius of the conducting wire 5 is, for example, 25 μm or more and 2000 μm or less, or preferably 50 μm or more and 200 μm or less.

[0190] The insulating layer 6 is a layer for protecting the conductor 5 from chemicals and water and for preventing short-circuiting of the conductor 5. The insulating layer 6 is disposed so as to cover the entire outer peripheral surface of the conductor 5.

[0191] The insulating layer 6 has, for example, a generally circular ring shape in cross section that shares a central axis with the wiring 2 .

[0192] Examples of materials for the insulating layer 6 include insulating resins such as polyvinyl formal, polyester, polyesterimide, polyamide (including nylon), polyimide, polyamideimide, polyurethane, etc. These may be used alone or in combination of two or more.

[0193] The insulating layer 6 may be composed of a single layer or multiple layers.

[0194] The thickness of the insulating layer 6 is approximately uniform in the radial direction of the wiring 2 at any position in the circumferential direction, and is, for example, 1 μm or more and 100 μm or less, preferably 3 μm or more and 50 μm or less.

[0195] <Method for manufacturing inductor> For example, as shown in Figures 2A to 2C, such an inductor 10 is manufactured by a manufacturing method including a preparation step of preparing a pre-cured soft magnetic film 1' and wiring 2, an arrangement step of arranging the pre-cured soft magnetic film 1' and wiring 2, and a curing step of curing the pre-cured soft magnetic film 1'.

[0196] First, in the preparation step, for example, a soft magnetic film 1' before being completely cured and a wiring 2 are prepared. Specifically, in the preparation step, as shown in Fig. 2A , the wiring 2 is prepared on one side in the thickness direction of one soft magnetic film 1' before being completely cured, and another soft magnetic film 1' before being completely cured is prepared on one side in the thickness direction of the wiring 2.

[0197] The soft magnetic film 1' before being completely cured may be used alone or in a plurality as shown in FIG. 2A.

[0198] The soft magnetic film 1' before being fully cured contains a resin component 3 and flat soft magnetic particles 4. The flat soft magnetic particles 4 are dispersed, for example, in a two-dimensional in-plane direction of the soft magnetic film 1' before being fully cured. The soft magnetic resin composition may contain other additives in addition to the resin component 3 and the flat soft magnetic particles 4, but these other additives are not shown.

[0199] 2B , in the arrangement step, for example, the soft magnetic film 1′ before being completely cured and the wiring 2 are arranged. Specifically, in the arrangement step, the wiring 2 and the soft magnetic film 1′ before being completely cured are arranged so as to cover the entire outer peripheral surface of the wiring 2.

[0200] A method for arranging the pre-fully cured soft magnetic film 1' so as to cover the entire outer peripheral surface of the wiring 2 is, for example, to press one pre-fully cured soft magnetic film 1' and another pre-fully cured soft magnetic film 1' together so as to sandwich the wiring 2, thereby deforming the one pre-fully cured soft magnetic film 1' and the other pre-fully cured soft magnetic film 1' and burying the wiring 2.

[0201] This allows the two soft magnetic films 1 ′ before being completely cured to be arranged so as to cover the entire outer peripheral surface of the wiring 2 .

[0202] 2C , in the curing step, the two pre-cured soft magnetic films 1′ are heated and cured to form the soft magnetic film 1. Note that the curing process causes the contact interface between the two pre-cured soft magnetic films 1′ to disappear, and the two pre-cured soft magnetic films 1′ form one soft magnetic film 1.

[0203] In the disposing step, the soft magnetic film 1 may be heated and cured at the same time as pressing, to form the soft magnetic film 1. In this case, the curing step can be omitted.

[0204] As a result, the inductor 10 is obtained.

[0205] (Modification of Inductor) The inductor 10 described above includes only the wiring 2 and the soft magnetic film 1, but is not limited to this.

[0206] Specifically, although not shown, an adhesive layer may be provided between the wiring 2 and the soft magnetic film 1 .

[0207] The adhesive used in the adhesive layer is not particularly limited as long as it is a known adhesive that is commonly used as an adhesive for inductor 10, and examples include epoxy-based adhesives, polyimide-based adhesives, and acrylic-based adhesives.

[0208] The thickness of the adhesive applied is, for example, 10 μm or more and 100 μm or less.

[0209] Although not shown, a modified example of the inductor 10 described above can be manufactured using the soft magnetic film 1, the wiring 2, and an adhesive.

[0210] Specifically, in the preparation process, wiring 2 is prepared on one thickness side (the adhesive-applied side) of one soft magnetic film 1 with adhesive applied to one thickness side, and another soft magnetic film 1 is prepared with adhesive applied to one thickness side of wiring 2 on the other thickness side.

[0211] Next, in the placement process, one soft magnetic film 1 and another soft magnetic film 1 are pressed together to sandwich the wiring 2, thereby embedding the wiring 2 so that it is sandwiched between the one soft magnetic film 1 and the other soft magnetic film 1 via the adhesive.

[0212] This allows the soft magnetic film 1 to be disposed via the adhesive so as to cover the entire outer peripheral surface of the wiring 2 .

[0213] When the soft magnetic film 1 is used, the curing step is omitted.

[0214] As a result, the inductor 10 is obtained.

[0215] 4. Magnetic Wiring Circuit Board One embodiment of a magnetic wiring circuit board using the soft magnetic film of the present disclosure will be described with reference to FIG.

[0216] The magnetic wiring circuit board 11 includes, for example, a soft magnetic film 1 and a circuit board 7 .

[0217] 3, the magnetic wiring circuit board 11 includes, for example, a circuit board 7 and a soft magnetic film 1 in that order in the thickness direction (stacking direction). That is, the magnetic wiring circuit board 11 includes, for example, the soft magnetic film 1 on one surface of the circuit board 7 in the thickness direction.

[0218] <Method for manufacturing magnetic wiring circuit board> Such a magnetic wiring circuit board 11 is manufactured by a manufacturing method including, for example, a preparation step of preparing a pre-cured soft magnetic film 1′ and a circuit board 7, a lamination step of laminating the pre-cured soft magnetic film 1′ on the circuit board 7, and a curing step of curing the pre-cured soft magnetic film 1′.

[0219] First, prepare a soft magnetic film 1′ before being completely cured and a circuit board 7. Specifically, prepare a soft magnetic film 1′ before being completely cured and a circuit board 7 having a wiring pattern 8 formed on the surface of a substrate 9.

[0220] The soft magnetic film 1' before being completely cured may be used singly or in plural.

[0221] The soft magnetic film 1′ before being completely cured contains a resin component 3 and flat soft magnetic particles 4. The flat soft magnetic particles 4 are, for example, arranged in a two-dimensional in-plane direction of the soft magnetic film 1′ before being completely cured. Note that the soft magnetic resin composition may contain additives other than the resin component 3 and the flat soft magnetic particles 4.

[0222] The circuit board 7 is, for example, a circuit board used in an electromagnetic induction system, and has a wiring pattern 8 such as a loop coil formed on one surface of the board 7 in the thickness direction.

[0223] The wiring pattern 8 is made of a metal material such as copper, and is formed by a semi-additive method or a subtractive method.

[0224] The substrate 9 is made of, for example, an insulating material, such as a glass epoxy substrate, a glass substrate, a polyethylene terephthalate (PET) substrate, a ceramic substrate, or a polyimide substrate.

[0225] Next, in the lamination step, for example, the soft magnetic film 1′ before being completely cured is laminated on one surface in the thickness direction of the circuit board 7. Specifically, the soft magnetic film 1′ before being completely cured is brought into contact with one surface in the thickness direction of the circuit board 7.

[0226] The soft magnetic film 1' before being completely cured may be pressed from one side of the circuit board 7 in the thickness direction to the other side in the thickness direction.

[0227] Next, in the curing step, the soft magnetic film 1 ′ before being completely cured is heated and cured to form the soft magnetic film 1 .

[0228] In the lamination step, the soft magnetic film 1 may be heated and cured at the same time as pressing, in order to form the soft magnetic film 1. In this case, the curing step can be omitted.

[0229] As a result, the magnetic wired circuit board 11 is obtained.

[0230] (Modification of Magnetic Wiring Circuit Board) The magnetic wiring circuit board 11 described above includes the circuit board 7 and the soft magnetic film 1 in this order in the thickness direction (stacking direction), but is not limited to this.

[0231] Specifically, although not shown, the magnetic wiring circuit board may include a circuit board 7, an adhesive layer, and a soft magnetic film 1 in this order in the thickness direction (stacking direction).

[0232] (Applications) Such a soft magnetic film 1 can be used for antennas, coils, etc. equipped in electronic devices. Furthermore, as described above, the soft magnetic film 1 can be used for the inductor 10, and can be mounted in electronic devices and used as a passive element such as a voltage conversion member.

[0233] The present disclosure will be described in more detail below with reference to examples and comparative examples. It should be noted that the present disclosure is not limited to these examples and comparative examples. The specific numerical values ​​of the blending ratios (content ratios), physical property values, parameters, etc. used in the following description can be replaced with the upper limit (a numerical value defined as "equal to or less than") or lower limit (a numerical value defined as "equal to or more than") of the corresponding blending ratios (content ratios), physical property values, parameters, etc. described in the above-mentioned "Modes for Carrying Out the Invention."

[0234] <Details of Components> The trade names and abbreviations of the components used in each example and comparative example are described in detail below.

[0235] Fe-Si alloy: Coercive force 500A / m, density 7.17g / cm ３ Orthocresol novolac epoxy resin: trade name "Epiclon N665-EXPS", manufactured by DIC Corporation, epoxy equivalent 200 g / eq, density 1.19 g / cm ３ Acrylic acid ester polymer: trade name "Teisan Resin SG-70LN", manufactured by Nagase ChemteX Corporation, solid content concentration 12.5% ​​by mass (methyl ethyl ketone solution), density 1.0 g / cm ３ Biphenylene aralkyl phenolic resin: trade name "MEHC-7851SS", manufactured by Meiwa Kasei Co., Ltd., hydroxyl group equivalent 203 g / eq, density 1.19 g / cm ３ Imidazole compound: trade name "2PHZ-PW", manufactured by Shikoku Chemicals Corporation, solid content concentration 10.0 mass% (methyl ethyl ketone solution), density 1.33 g / cm ３

[0236] Example 1 <Preparation of Soft Magnetic Particles> An Fe—Si alloy, which is a soft magnetic material, was processed into spherical soft magnetic particles by gas atomization, and these soft magnetic particles were classified. Next, a predetermined amount of the classified soft magnetic particles was placed in an attritor. Alcohol and powder media were also placed in this attritor. The spherical soft magnetic particles were processed into a flattened shape using the attritor, and the resulting roughly refined flat soft magnetic particles were classified using a mesh to obtain flat soft magnetic particles of Example 1 with a desired particle diameter (particle size distribution).

[0237] The particle diameters D10, D50, and D90 of the flat soft magnetic particles of Example 1 were measured using a laser diffraction particle size distribution analyzer (LS 13 320, manufactured by Beckman Coulter, Inc.). The results are shown in Table 3.

[0238] <Preparation of Soft Magnetic Resin Composition> Next, a soft magnetic resin composition was prepared based on the composition shown in Preparation Example (I) in Table 1. Specifically, 380 parts by mass of the flat soft magnetic particles of Example 1, 12.7 parts by mass of an orthocresol novolac epoxy resin as the epoxy resin, 163.5 parts by mass (solid content 20.4 parts by mass) of an acrylic acid ester polymer solution as the acrylic resin, 12.7 parts by mass of a biphenylene aralkyl phenol resin as the curing agent, and 4.6 parts by mass of an imidazole compound solution (solid content 0.5 parts by mass) as the curing accelerator were mixed.

[0239] Next, 452.9 parts by mass of methyl ethyl ketone was added to the mixture as a dispersion medium to prepare a soft magnetic resin composition with a solid content concentration of 11.3% by volume.

[0240] In Preparation Example (I), the mass (g) and volume (cm) of each component of the soft magnetic resin composition are ３ ), solid mass (g), and solid volume (cm ３ ) are shown in Table 1. Table 2 also shows the content (mass % and volume %) of resin components (components other than flat soft magnetic particles) in the solid content of the soft magnetic resin composition, the content (mass % and volume %) of flat soft magnetic particles in the solid content of the soft magnetic resin composition, the solid content concentration (mass % and volume %) of the soft magnetic resin composition, and the content (mass % and volume %) of flat soft magnetic particles in the soft magnetic resin composition in Preparation Example (I).

[0241] Examples 2 and 3 Flat soft magnetic particles of Examples 2 and 3 were obtained in the same manner as Example 1, except that the processing time using the attritor was changed. The particle diameters D10, D50, and D90 of the soft magnetic particles of Examples 2 and 3 were measured in the same manner as Example 1. The results are shown in Table 3.

[0242] In addition, soft magnetic resin compositions of Examples 2 and 3 were prepared in the same manner as in Example 1, except that the flat soft magnetic particles of Examples 2 and 3 were used.

[0243] Example 4 Flat soft magnetic particles of Example 4 were obtained in the same manner as in Example 1, except that the processing time with the attritor and the subsequent mesh size of the classification mesh were changed. The particle diameters D10, D50, and D90 of the soft magnetic particles of Example 4 were measured in the same manner as in Example 1. The results are shown in Table 3.

[0244] A soft magnetic resin composition of Example 4 was prepared in the same manner as in Example 1, except that the flat soft magnetic particles of Example 4 were used.

[0245] Comparative Example 1 Flat soft magnetic particles of Comparative Example 1 were obtained in the same manner as in Example 1, except that in the processing using an attritor, the predetermined processing amount of the raw material powder and the processing time were changed, and the mesh size of the classification mesh was then changed. The particle diameters D10, D50, and D90 of the soft magnetic particles of Comparative Example 1 were measured in the same manner as in Example 1. The results are shown in Table 3.

[0246] A soft magnetic resin composition of Comparative Example 1 was prepared in the same manner as in Example 1, except that the flat soft magnetic particles of Comparative Example 1 were used.

[0247] Comparative Example 2 A soft magnetic resin composition of Comparative Example 2 was prepared in the same manner as in Example 1, except that the flat soft magnetic particles of Example 4 were used and the amount of the dispersion medium was changed based on the composition shown in Preparation Example (II) described in Table 1. The solid content concentration of the soft magnetic resin composition of Comparative Example 2 was 10.3% by volume.

[0248] In addition, the mass (g) and volume (cm) of each component of the soft magnetic resin composition in Preparation Example (II) are shown below. ３ ), solid mass (g), and solid volume (cm ３) are shown in Table 1. Furthermore, in Preparation Example (II), Table 2 shows the content (mass % and volume %) of resin components (components other than flat soft magnetic particles) in the solid content of the soft magnetic resin composition, the content (mass % and volume %) of flat soft magnetic particles in the solid content of the soft magnetic resin composition, the solid content concentration (mass % and volume %) of the soft magnetic resin composition, and the content (mass % and volume %) of flat soft magnetic particles in the soft magnetic resin composition.

[0249] <Evaluation> [Viscosity] The viscosity of the soft magnetic resin composition of each example and each comparative example was measured at 25°C. For the viscosity measurement, a viscometer (trade name "RE-85", manufactured by Toki Sangyo Co., Ltd.) and a cone rotor (trade name "1°34' x R24", 1.1 ml, shear rate: 3.83 N (1 / s), manufactured by Toki Sangyo Co., Ltd.) were used, and the viscosity was measured at each shear rate. The rotation speed of the cone rotor was determined at four points: 10 rpm, 20 rpm, 50 rpm, and 100 rpm. The relationship between the rotation speed N (rpm) and the shear rate, i.e., the shear rate, for the cone rotor used was 3.83 N (1 / s). －１ ), the shear rate at each measurement point is 38.3 (s －１ ), and 76.6 (s －１ ), and 191.5 (s －１ ), and 383 (s) at 100 rpm －１ The viscosity at each shear rate was designated A to D. The results are shown in Table 3. The relationship between shear rate and viscosity is shown in the graph of Figure 4.

[0250] The ratios of viscosity A to viscosities B to D (A / B, A / C, and A / D) were also calculated. The results are shown in Table 3.

[0251] [Continuous Coatability] The soft magnetic resin composition of each Example and Comparative Example was continuously coated onto a release liner (average thickness: 50 μm) made of a silicone release-treated polyethylene terephthalate film using a comma head coater. The coating speed was 10 m / min, and the coating gap was 350 μm. With regard to continuous coatability, the appearance of the soft magnetic resin composition on the film was evaluated according to the following criteria. The results are shown in Table 3. There was almost no change in the appearance of each soft magnetic resin composition on the film between the state immediately after coating and the state after drying.

[0252] {Criteria} Good: The coating was evenly applied to the film. Bad: The coating could not be applied to the film, or the coating could not be evenly applied to the film (there were streaks or gaps).

[0253] [Magnetic Permeability] The soft magnetic resin composition of each Example and Comparative Example was continuously coated onto a release liner (average thickness: 50 μm) made of a silicone release-treated polyethylene terephthalate film using a comma head coater, and then dried at 110°C for 2 minutes. This produced a pre-fully cured soft magnetic film laminated on the release liner (average thickness of the pre-fully cured soft magnetic film alone: ​​140 μm). Four of these pre-fully cured soft magnetic films were produced, and these soft magnetic films (excluding the release liner) were laminated together. The four pre-fully cured soft magnetic films laminated together were hot-pressed at 9 MPa, 170°C, and 15 minutes to produce a soft magnetic film with a thickness of 150 μm.

[0254] Next, the magnetic permeability of the soft magnetic films formed from the soft magnetic resin compositions of each of the Examples and Comparative Examples was determined by measuring the impedance at 10 MHz using an impedance analyzer (E4991B Impedance Analyzer, manufactured by KEYSIGHT Corporation). The results are shown in Table 3.

[0255]

[0256]

[0257]

[0258] The above invention is provided as an exemplary embodiment of the present disclosure, but this is merely an example and should not be interpreted as limiting. Modifications of the present disclosure that are obvious to those skilled in the art are intended to be included in the scope of the following claims.

[0259] A soft magnetic film formed from the soft magnetic resin composition of the present disclosure can be suitably used for antennas and coils provided in electronic devices. Furthermore, such a soft magnetic film can be used for an inductor, and can be mounted on an electronic device and used as a passive element such as a voltage conversion member. Furthermore, such a soft magnetic film can also be used for a magnetic wiring circuit board.

[0260] REFERENCE SIGNS LIST 1 soft magnetic film 2 wiring 3 resin component 4 flat soft magnetic particles 10 inductor

Claims

1. A solid component containing flat soft magnetic particles and a resin component, and a dispersion medium, and a shear rate of 38.1 s －１ The viscosity (A) at a shear rate of 191.5 s is 300 mPa·s or more. －１ Viscosity (C) at shear rate of 38.1 s －１ The soft magnetic resin composition has a viscosity (A) ratio (A / C) of 1.70 or more.

2. A soft magnetic resin composition as described in claim 1, wherein the particle diameter (D90) at which the volume-based cumulative value from the small particle side of the flat soft magnetic particles is 90% is 80 μm or more and 130 μm or less.

3. The soft magnetic resin composition according to claim 1, wherein the particle diameter (D50) at which the volume-based cumulative value from the small particle side of the flat soft magnetic particles is 50% is 30 μm or more and 50 μm or less.

4. The soft magnetic resin composition according to claim 1, wherein the particle diameter (D10) at which the volume-based cumulative value from the small particle side of the flat soft magnetic particles is 10% is 5 μm or more.

5. The soft magnetic resin composition according to claim 1, wherein the solid content concentration of the soft magnetic resin composition is 11 volume % or more and 14 volume % or less.

6. The soft magnetic resin composition according to claim 1, wherein the resin component includes a thermosetting resin component and a thermoplastic resin component.

7. The soft magnetic resin composition according to claim 6, wherein the thermosetting resin component includes an epoxy resin, and the thermoplastic resin component includes an acrylic resin.

8. The soft magnetic resin composition according to claim 7, wherein the thermosetting resin component further comprises a curing agent and a curing accelerator.

9. The soft magnetic resin composition according to claim 1, wherein the content of the flat soft magnetic particles in the solid content of the soft magnetic resin composition is 45 volume % or more and 70 volume % or less.

10. The soft magnetic resin composition according to claim 1, wherein a cured product of the soft magnetic resin composition has a magnetic permeability of 40 or more at a frequency of 10 MHz.

11. A soft magnetic film which is a cured product of the soft magnetic resin composition according to any one of claims 1 to 10.

12. An inductor comprising the soft magnetic film and wiring according to claim 11.

13. A method for producing a soft magnetic film, comprising: a coating step of continuously coating a substrate with the soft magnetic resin composition according to any one of claims 1 to 10 at a coating speed of 5 m / min or more; a drying step of drying a dispersion medium contained in the soft magnetic resin composition coated on the substrate to obtain a soft magnetic film before completely curing; and a curing step of thermally curing the soft magnetic film before completely curing.

14. The method for producing a soft magnetic film according to claim 13, wherein in the coating step, the coating speed is increased continuously or stepwise until the coating speed becomes 5 m / min or more.

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