Magnetic resin composition, cured product, and electronic component

Abstract

The present invention provides a magnetic resin composition, a cured product formed by curing the magnetic resin composition, and an electronic component including the cured product. The magnetic resin composition contains magnetic particles and an epoxy resin having an epoxy equivalent of 400 g / eq or more, and the filling rate of the magnetic particles is 70% or more based on area.

Description

Technical Field

[0001] The present invention relates to a magnetic resin composition, a cured product and an electronic component. Background Art

[0002] Conventionally, electronic component parts (for example, coil component parts such as inductors, transformer cores, electromagnetic noise absorbers, electromagnetic wave absorbers, etc.) have been produced using compositions containing magnetic particles (for example, see Patent Documents 1 and 2).

[0003] Previous technical literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-123376

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 7-169613 Summary of the Invention

[0007] Technical issues to be solved by the invention

[0008] Electronic components for high-frequency devices such as personal computers, automobiles, and mobile phones, flat-panel displays, game consoles, road information systems, and wireless LANs (Local Area Networks) can reduce noise and stabilize voltage in these devices. It is said that having components containing magnetic particles in these electronic components increases the magnetic permeability (specifically, the real part of the complex magnetic permeability, μr'), thereby enabling miniaturization of the electronic components. In recent years, as the operating frequency of electronic components has increased, components containing magnetic particles have become more desirable, with a high magnetic permeability μr' in the high-frequency band (e.g., around 100 MHz).

[0009] The above-mentioned parts containing magnetic particles can be produced, for example, as follows. A composition containing magnetic particles and a resin is solidified to produce a solidified product. The solidified product is then cut into a size and / or shape according to the intended use. Therefore, parts containing magnetic particles can be produced. However, if cracks are generated in the solidified product during processing, the quality of the produced parts will be reduced. Therefore, it is desired that the composition containing magnetic particles and a resin is less likely to produce cracks in the solidified product during processing.

[0010] However, according to the studies of the present inventors, there is a demand for further improvement of the conventional composition containing magnetic particles and a resin in relation to the above-mentioned points.

[0011] An object of one embodiment of the present invention is to provide a composition containing magnetic particles and a resin, which can produce a cured product having a high magnetic permeability μr′ in a high frequency band and capable of suppressing the generation of cracks during processing.

[0012] Means for solving technical problems

[0013] One embodiment of the present invention relates to a magnetic resin composition comprising:

[0014] magnetic particles; and

[0015] An epoxy resin having an epoxy equivalent weight of 400 g / eq or more, and

[0016] The filling rate of the magnetic particles is 70% or more based on the area.

[0017] In one embodiment, the porosity of the magnetic resin composition can be less than 0.30% on an area basis.

[0018] In one embodiment, the magnetic particles may include metal particles.

[0019] In one embodiment, the metal particles may include Ni and Fe.

[0020] In one embodiment, the metal particles may further contain Mo.

[0021] In one embodiment, the metal particles may have an average particle size of less than 10.0 μm.

[0022] In one embodiment, the magnetic particles may further include ferrite particles.

[0023] In one embodiment, the average particle size of the ferrite particles can be less than 1.0 μm.

[0024] In one embodiment, the coercive force Hc of the ferrite particles can be 30.0 Oe or more.

[0025] One embodiment of the present invention relates to a cured product obtained by curing the magnetic resin composition.

[0026] One embodiment of the present invention relates to an electronic component including the above-mentioned cured product.

[0027] Effects of the Invention

[0028] According to one embodiment of the present invention, a magnetic resin composition containing magnetic particles and a resin can be provided. This magnetic resin composition has a high magnetic permeability μr' in a high-frequency band and can suppress cracking during processing. Furthermore, according to one embodiment of the present invention, a cured product formed by curing the magnetic resin composition and an electronic component including the cured product can be provided. DETAILED DESCRIPTION

[0029] [Magnetic resin composition]

[0030] A magnetic resin composition according to one embodiment of the present invention (hereinafter also referred to simply as "composition") contains magnetic particles and an epoxy resin having an epoxy equivalent of 400 g / eq or greater, and has a filling rate of the magnetic particles of 70% or greater based on area.

[0031] In the present invention and this specification, the "filling fraction" of magnetic particles is determined by the following method. Furthermore, unless otherwise noted, the following steps and operations are performed at room temperature in the range of 20-25°C in air. This applies to all steps and operations described in this specification, unless otherwise noted.

[0032] 1. Preparation of film for filling rate measurement

[0033] A support (e.g., a resin film) having a release surface subjected to a release treatment is obtained as a commercial product or prepared by a known method. The composition for which the filling rate is to be determined is applied to the release surface of the support, and then heated in a heat treatment device with an internal ambient air temperature of 80°C for 1 hour. Thereafter, it is heated on a hot plate set at a temperature of 120°C for 10 minutes. Typically, a film of the above-mentioned composition partially cured in this manner is prepared on the release surface of the support. After the film is peeled off from the release surface of the support, it is heated in a heat treatment device with an internal ambient air temperature of 150°C for 20 minutes. Using the heated film, the filling rate is determined by the following method.

[0034] 2. Scanning Electron Microscope Image Acquisition and Filling Rate Calculation

[0035] A sample for cross-sectional observation is cut from a randomly specified position of the film produced in 1. above by a known device such as a microtome. The sample for cross-sectional observation is observed by a scanning electron microscope (SEM; Scanning Electron Microscope), and a cross-sectional image (SEM image) is taken. As the SEM, a field emission scanning electron microscope (FE (Field Emission)-SEM) is used. The taken SEM image is a secondary electron (Secondary Electron) image. Using FE-SEM, the sample for cross-sectional observation is assembled on a workbench, and a cross-sectional SEM image with a viewing angle of 32μm×42μm is obtained under the conditions of an acceleration voltage of 3kV and an observation magnification of 3000 times. After converting the obtained cross-sectional SEM image into a grayscale image, it is binarized with a brightness intermediate between the brightness of the magnetic particles and the brightness of the other areas, thereby determining the portion of the magnetic particles, and calculating the proportion (area basis) occupied by the determined portion of the magnetic particles. Regarding the porosity described later, the obtained cross-sectional SEM image is converted into a grayscale image as described above, and then binarized using the brightness intermediate between the brightness of the pore portion and the brightness of the remaining area. This identifies the pore portion (the portion where neither magnetic particles, resin, nor any optional additives are present), and the proportion of the identified pore portion is calculated (based on area). Furthermore, if necessary, the magnetic particle portion and / or pore portion in the cross-sectional SEM image can be identified by performing elemental analysis of the cross-sectional observation sample.

[0036] The above operation is performed on five cross-sectional observation samples cut from different positions of the thin film prepared in 1. above, and the filling rate of the magnetic particles can be calculated as the arithmetic average of the five values obtained. This also applies to the porosity.

[0037] In the present invention and this specification, the epoxy equivalent of an epoxy resin is the mass of the epoxy resin containing 1 equivalent of epoxy groups and is determined according to JIS K 7236: 2001. Regarding the unit of epoxy equivalent, "eq" represents an equivalent that cannot be converted into SI units.

[0038] For the magnetic resin composition, a filling rate of magnetic particles within the above range can help the cured product formed by curing the composition exhibit a high magnetic permeability μr' in the high-frequency band. Furthermore, if the resin contained in the magnetic resin composition is an epoxy resin with an epoxy equivalent within the above range, it can help suppress the occurrence of cracks during processing. The magnetic resin composition is described in further detail below.

[0039] <Magnetic particles>

[0040] (Fill rate)

[0041] The filling rate (area basis) of the magnetic particles of the magnetic resin composition is 70% or more. This can help the cured product formed by curing the composition to exhibit high magnetic permeability μr' in a high-frequency band. From the perspective of further increasing the magnetic permeability, the filling rate is preferably 71% or more, more preferably 72% or more. Furthermore, the filling rate can be, for example, 90% or less, 85% or less, 80% or less, or 75% or less. However, from the perspective of further increasing the magnetic permeability, the filling rate of the magnetic particles is preferably high, so the filling rate can exceed the value exemplified here.

[0042] As the magnetic particles, one kind or a combination of two or more kinds selected from the group consisting of magnetic particles generally called soft magnetic particles such as metal particles and ferrite particles can be used.

[0043] (Metal particles)

[0044] In the present invention and this specification, "metal particles" include pure metal particles composed of a single metal element and particles of alloys of one or more metal elements and one or more other metal elements and / or non-metallic elements. The presence or absence of crystallinity is irrelevant to the metal particles. That is, the metal particles can be crystalline particles or amorphous particles. Examples of metal or non-metal elements contained in the metal particles include Ni, Fe, Co, Mo, Cr, Si, B, P, etc. The metal particles may or may not contain components other than the constituent elements of the metal (including the alloy). In addition to the constituent elements of the metal (including the alloy), the metal particles may contain elements contained in additives that can be added arbitrarily and / or elements contained in impurities that may be unintentionally mixed in the manufacturing process of the metal particles at any content rate. In the metal particles, the content rate of the constituent elements of the metal (including the alloy) is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, and can be 100% by mass, or less than 100% by mass, 99.9% by mass or less, or 99.0% by mass or less.

[0045] In one embodiment, the metal particles can contain Ni and Fe, and can also contain Mo. For example, for electronic components, from the perspective of providing components that reduce performance degradation during long-term use and / or when placed in harsh environments, it is preferable to suppress the decrease in magnetic permeability μr' in an acidic environment. From the perspective of suppressing the decrease in magnetic permeability μr', magnetic particles that are not easily oxidized in an acidic environment are preferred. From this aspect, metal particles containing Ni and Fe are preferred, and metal particles containing Ni, Fe and Mo are more preferred. From the perspective of further suppressing the progress of oxidation in an acidic environment, as metal particles, in metal particles containing Ni and Fe or also containing Mo, the total content of Ni, Fe and Mo is preferably 90.0% by mass or more, more preferably 95.0% by mass or more, and can be 100% by mass, less than 100% by mass, 99.9% by mass or less, or 99.0% by mass or less. The content of Ni is preferably 20.0% by mass or more, more preferably 30.0% by mass or more, and preferably 90% by mass or less, more preferably 80% by mass or less. The content of Mo is preferably 0.5 mass % or more, more preferably 2 mass % or more, and is preferably 20 mass % or less, more preferably 10 mass % or less.

[0046] The average particle size of the metal particles can be, for example, 15.0 μm or less, 14.0 μm or less, 13.0 μm or less, 12.0 μm or less, 11.0 μm or less, 10.0 μm or less, or less than 10.0 μm. With regard to the physical properties of the components contained in the electronic parts, from the perspective of low loss of the electronic parts, it is preferred that the loss tangent tanδ of the electronic parts is small at the operating frequency. The loss tangent tanδ is calculated from the real part μr' of the complex magnetic permeability and the imaginary part μr" of the complex magnetic permeability by tanδ=μr" / μr'. From the perspective of being able to produce components with a small loss tangent tanδ in a high frequency band (for example, around 100 MHz), as metal particles, metal particles having an average particle size of less than 10.0 μm are preferred, more preferably less than 9.9 μm, further preferably less than 9.5 μm, further preferably less than 9.0 μm, and further preferably less than 8.5 μm. The average particle size of the metal particles may be, for example, 3.0 μm or more, 3.5 μm or more, 4.0 μm or more, or more. From the perspective of further increasing magnetic permeability, the average particle size of the metal particles is preferably more than 4.0 μm, more preferably 4.1 μm or more, and even more preferably 4.5 μm or more.

[0047] In the present invention and this specification, unless otherwise specified, the average particle size of various particles is a value measured by the following method using a scanning electron microscope.

[0048] Particles were photographed using a transmission electron microscope at 3000x magnification. Target particles were selected from the photographs and their outlines were traced using a digitizer to measure their size (primary particles). Primary particles are independent, unagglomerated particles.

[0049] The above measurement is performed on 500 randomly selected particles. The arithmetic mean of the particle sizes of the 500 particles thus obtained is taken as the average particle size of the particles. As the scanning electron microscope, for example, a FE-SEM S4800 manufactured by Hitachi, Ltd. can be used. Furthermore, the particle size can be measured using known image analysis software, such as the image analysis software KS-400 manufactured by Carl Zeiss.

[0050] In the present invention and this specification, unless otherwise specified, the size of the primary particles of the particles refers to the shape of the particles observed in the above-mentioned particle photographs.

[0051] (1) In the case of a needle-like, spindle-like, columnar shape (however, the height is greater than the maximum diameter of the base), the particle length is represented by the length of the major axis constituting the particle, i.e., the major axis length.

[0052] (2) In the case of a plate or column (however, the thickness or height is less than the maximum major diameter of the plate surface or bottom surface), it is represented by the maximum major diameter of the plate surface or bottom surface.

[0053] (3) When the particle is spherical, polyhedral, or irregular in shape and the major axis of the particle cannot be determined from the shape, the particle is represented by the equivalent circle diameter. The equivalent circle diameter is the diameter obtained by the circular projection method.

[0054] The average particle size of the magnetic particles contained in the magnetic resin composition can be determined by, for example, performing the above-mentioned measurement on the magnetic particles used to produce the magnetic resin composition or on magnetic particles from the same batch as the magnetic particles. Furthermore, the average particle size of the magnetic particles contained in the magnetic resin composition can be determined by, for example, extracting magnetic particles from the magnetic resin composition or its cured product using a known method and performing the above-mentioned measurement on the extracted magnetic particles. This also applies to the coercive force Hc of the magnetic particles.

[0055] Regarding the magnetic properties of metal particles, the coercive force Hc of the metal particles can be within the same range as particles generally referred to as soft magnetic particles, for example, 100.0 Oe (Oe) or less, 90.0 Oe or less, 80.0 Oe or less, 70.0 Oe or less, 60.0 Oe or less, 50.0 Oe or less, 40.0 Oe or less, 30.0 Oe or less, less than 30.0 Oe, or 20.0 Oe or less. Furthermore, the coercive force Hc of the metal particles can be, for example, 1.0 Oe or greater, 2.0 Oe or greater, or 3.0 Oe or greater. Furthermore, regarding units, 1 Oe (1 Oe) = 79.6 A / m.

[0056] The coercive force Hc of magnetic particles can be measured using a known vibrating sample magnetometer. In the present invention and this specification, the coercive force Hc is a value measured at a measurement temperature of 25°C ± 1°C. The measurement temperature is the ambient temperature of the gas surrounding the particle being measured during the coercive force measurement.

[0057] (Ferrite particles)

[0058] Ferrite particles can also be used as the magnetic particles. From the perspective of further increasing magnetic permeability, it is preferable to use a combination of metal particles and ferrite particles. The content of the ferrite particles is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, relative to 100 parts by mass of the metal particles. Furthermore, the content of the ferrite particles can be, for example, 20 parts by mass or less, 15 parts by mass or less, or 10 parts by mass or less relative to 100 parts by mass of the metal particles.

[0059] Ferrite particles are particles whose crystal structure is revealed by X-ray diffraction analysis. As ferrite particles, for example, one or more types of ferrite particles of known compositions such as Ni-Zn ferrite particles, Mn-Zn ferrite particles, and Ni-Cu-Zn ferrite particles can be used.

[0060] From the perspective of increasing the filling rate of magnetic particles in the magnetic resin composition, the average particle size of the ferrite particles is preferably less than 1.0 μm, more preferably 0.9 μm or less. Furthermore, the average particle size of the ferrite particles can be, for example, 0.1 μm or greater, 0.3 μm or greater, or 0.5 μm or greater. In one embodiment, from the perspective of increasing the filling rate of magnetic particles in the magnetic resin composition, it is preferred that the ferrite particles have an average particle size smaller than that of the metal particles.

[0061] Regarding the magnetic properties of ferrite particles, the coercive force Hc of ferrite particles can be within the same range as particles commonly referred to as soft magnetic particles, for example, it can be below 100.0Oe, below 90.0Oe, below 80.0Oe, below 70.0Oe, below 60.0Oe or below 50.0Oe. Furthermore, the coercive force Hc of ferrite particles can be, for example, above 1.0Oe, above 5.0Oe, above 10.0Oe, above 15.0Oe, above 20.0Oe, above 25.0Oe or above 30.0Oe. From the viewpoint of being able to produce components with a small loss tangent tanδ in a high frequency band (for example, around 100MHz), it is preferred to use ferrite particles with a coercive force Hc of 30.0Oe or more as ferrite particles. From this viewpoint, the coercive force Hc of ferrite particles is more preferably above 35.0Oe, and further preferably above 40.0Oe.

[0062] (Epoxy resin)

[0063] The magnetic resin composition contains an epoxy resin with an epoxy equivalent weight of 400 g / eq or greater. Epoxy resin is a thermosetting resin containing epoxy groups. Compositions containing epoxy resins can be cured by heating to form a crosslinked structure by ring-opening the epoxy groups contained in the epoxy resin. In the magnetic resin composition, an epoxy equivalent weight of 400 g / eq or greater in the epoxy resin contained together with the magnetic particles can help produce a cured product from the composition that suppresses cracking during processing. The epoxy equivalent weight is 400 g / eq or greater, preferably 401 g / eq or greater, more preferably 403 g / eq or greater, and even more preferably 405 g / eq or greater. Furthermore, from the perspective of increasing the strength of a cured product formed from the magnetic resin composition, the epoxy equivalent weight is preferably 2000 g / eq or less, more preferably 1800 g / eq or less, and even more preferably 1600 g / eq or less.

[0064] The content of the epoxy resin in the magnetic resin composition is preferably in the range of 1 to 20 parts by mass, more preferably in the range of 3 to 10 parts by mass, based on 100 parts by mass of the magnetic particles.

[0065] Examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, bisphenol AF epoxy resin, dicyclopentadiene epoxy resin, trisphenol epoxy resin, naphthol novolac epoxy resin, phenol novolac epoxy resin, tert-butyl-catechol epoxy resin, naphthalene epoxy resin, naphthol epoxy resin, anthracene epoxy resin, glycidylamine epoxy resin, glycidyl ester epoxy resin, cresol novolac epoxy resin, biphenyl epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexanedimethanol epoxy resin, naphthylene ether epoxy resin, trimethylol epoxy resin, and the like. The epoxy resin may be used alone or in combination of two or more in any proportion. In the cured product formed by curing the magnetic resin composition, some or all of the epoxy groups contained in the epoxy resin may be ring-opened to form a crosslinked structure. Furthermore, when the magnetic resin composition contains two or more epoxy resins, the epoxy resin content described above refers to the total content of these two or more epoxy resins. This also applies to the contents and content ratios of the other components.

[0066] (Optional ingredient)

[0067] In one embodiment, the magnetic resin composition may contain only one or more magnetic particles and one or more epoxy resins. In another embodiment, the magnetic resin composition may contain any amount of known additives. Examples of additives include components that can act as curing agents for epoxy resins, components that can act as dispersants for magnetic particles, coupling agents, surfactants, and the like. Such components are well known, and examples include phenol compounds, amine compounds, imidazole compounds, acid anhydrides, and polymer-based dispersants. For example, the use of a dispersant can help improve the dispersibility of the magnetic particles in the magnetic resin composition and increase the filling rate. Furthermore, the porosity can be reduced by improving the dispersibility of the magnetic particles.

[0068] The magnetic resin composition may be solvent-free, or it may contain one or more solvents, for example, to improve coating properties. Examples of the solvent include various organic solvents, such as ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone; acetate solvents such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbon solvents such as toluene and xylene; and amide solvents such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone. The solvent can be selected based on, for example, the solubility of the ingredients used to prepare the magnetic resin composition. A single solvent or a mixture of two or more solvents in any proportion can be used. If the magnetic resin composition contains a solvent, the solvent can be used in any amount based on, for example, the coating properties of the composition.

[0069] Porosity

[0070] For the magnetic resin composition, a low porosity (area basis) determined by the method described above can contribute to an increased filling rate of magnetic particles and / or further increased magnetic permeability of a cured product formed from the composition. In this regard, the porosity of the magnetic resin composition is preferably less than 0.30%, more preferably 0.25% or less, even more preferably 0.20% or less, even more preferably 0.15% or less, even more preferably 0.10% or less, even more preferably 0.08% or less, even more preferably 0.06% or less, and even more preferably 0.04% or less. The porosity of the magnetic resin composition can be, for example, 0% or greater, greater than 0%, or 0.01% or greater.

[0071] The magnetic resin composition can be prepared by mixing the various components sequentially in any order or simultaneously. Furthermore, as needed, the composition can be dispersed using a known disperser such as a ball mill, a bead mill, a sand mixer, or a roller mill, and / or stirred using a known stirrer such as a vibrating stirrer.

[0072] [Solidified products, electronic parts]

[0073] One embodiment of the present invention relates to a cured product formed by curing a magnetic resin composition.

[0074] Furthermore, one embodiment of the present invention relates to an electronic component including the above-mentioned cured product.

[0075] The cured product obtained by curing the magnetic resin composition can be produced, for example, as follows in one embodiment.

[0076] The magnetic resin composition is coated on a support. Coating can be performed using a known coating device such as a knife coater or a die coater. Coating can also be performed by a so-called roll-to-roll method or a batch method. As a support, for example, films of various resins such as polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylic acids such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetyl cellulose (TAC), polyether sulfide (PES), polyether ketone, and polyimide can be cited. For these resin films, reference can be made to paragraphs 0081 to 0086 of Japanese Patent Application Publication No. 2015-187260. As a support, a support to which a peeling treatment is applied to the surface (coated surface) coated with the magnetic resin composition by a known method can be used. As one way of peeling treatment, a release layer can be formed. For details about the release layer, see paragraph 0084 of Japanese Patent Application Laid-Open No. 2015-187260. Furthermore, a commercially available release-treated resin film can be used as the support. By using a support with a release-treated surface, the cured magnetic resin composition can be easily separated from the support after curing.

[0077] Furthermore, in one embodiment, the magnetic resin composition can be directly applied to an electronic component on which a coating layer formed by curing the composition is to be provided.

[0078] The coating layer formed by applying the magnetic resin composition can be dried by known methods such as heating and blowing warm air. The drying treatment can be carried out, for example, under conditions that can volatilize the solvent contained in the magnetic resin composition. After the drying treatment is arbitrarily carried out, the magnetic resin composition can be subjected to a curing treatment. The curing treatment can be a heating treatment for carrying out a curing reaction of the epoxy resin (specifically, the ring opening of the epoxy group and the formation of a cross-linked structure). The conditions of the heating treatment (temperature, time, etc.) can be set according to the type of epoxy resin contained in the magnetic resin composition, the composition of the composition, etc. The heating treatment can be a single-stage heating treatment or a multi-stage heating treatment of two or more stages. For example, after a partial curing reaction is carried out by the first-stage heating treatment to form a partially cured product, the partially cured product can be subjected to a second or subsequent stage heating treatment to fully carry out the curing reaction.

[0079] In the present invention and this specification, the cured product obtained by curing the magnetic resin composition includes a partially cured product (generally referred to as a semi-cured product, etc.) in which only a portion of the curing reaction of the epoxy resin contained in the magnetic resin composition has proceeded, and a cured product in which the curing reaction has proceeded to full or almost full capacity (generally referred to as a fully cured product, etc.).

[0080] The cured product includes a method of performing one or more processing treatments after the curing treatment and a method before the processing treatment. As a processing treatment, for example, a process of cutting into a predetermined size and shape using a known cutting device such as a cutter can be cited. The size and shape can be determined according to the type of electronic component to which the cured product after processing is used as a component, and are not particularly limited. By curing the cured product formed by curing the magnetic resin composition, the generation of cracks during processing can be suppressed.

[0081] The above-mentioned cured product can be used as a component of an electronic component. As components of electronic components, for example, components of coil components such as inductors, transformer cores, electromagnetic noise absorbers, electromagnetic wave absorbers, etc. can be cited. As an example, for the details of the coil components, reference can be made to paragraphs 0042 to 0061 of Japanese Patent Application Publication No. 2017-199801 and the drawings of the same publication. For example, the above-mentioned cured product can be provided to replace the magnetic resin layer in the coil component described in Japanese Patent Application Publication No. 2017-199801. Furthermore, with respect to inductors and electromagnetic noise absorbers, reference can be made to paragraphs 0056 and 0057 of Japanese Patent Application Publication No. 2013-204067. For example, the above-mentioned magnetic resin composition can be used to replace the magnetic paste described in Japanese Patent Application Publication No. 2013-204067. Regarding inductors, reference can be made to paragraphs 0032 to 0041 of Japanese Patent Application Laid-Open No. 2006-237506 and the accompanying drawings therein. For example, the magnetic resin composition described above can be used in place of the magnetic paste described in Japanese Patent Application Laid-Open No. 2006-237506. Furthermore, regarding electromagnetic wave absorbers, reference can be made to paragraphs 0015 and 0016, and Figures 1, 3, and 4 of Japanese Patent Application Laid-Open No. 2001-77585. For example, the magnetic resin composition described above can be used in place of the electromagnetic wave absorbing paste described in Japanese Patent Application Laid-Open No. 2001-77585.

[0082] Furthermore, as one form of electronic components, an inductor commonly referred to as a planar inductor can also be cited. In one form, the above-mentioned electronic component can be an electronic component including an inductor element. As such an electronic component, for example, a wiring board can be cited. For details of the wiring board, reference can be made to paragraphs 0098 to 0155 of Japanese Patent Application Publication No. 2015-187260 and Figures 1 to 3 of the same publication. The wiring board can also include semiconductor chips, etc. Furthermore, using the wiring board, various types of semiconductor devices can be manufactured. The semiconductor device including the wiring board can be preferably used in mobile information terminals such as automobiles and mobile phones, flat-panel displays, game consoles, road information systems, wireless LANs, and other high-frequency devices.

[0083] As electronic components, electronic components with operating frequencies in the high-frequency band of around 100 MHz have attracted much attention in recent years. The magnetic permeability μr' of a cured product formed by curing a magnetic resin composition according to one embodiment of the present invention at a frequency of, for example, 100 MHz can be 13.5 or more, or 14.0 or more. The above-mentioned magnetic permeability μr' can be, for example, 20.0 or less or 18.0 or less, or can exceed the values exemplified here. Furthermore, the loss tangent tanδ of a cured product formed by curing a magnetic resin composition according to one embodiment of the present invention at a frequency of, for example, 100 MHz can be 0.40 or less, 0.38 or less, 0.35 or less, or 0.30 or less. The above-mentioned loss tangent tanδ can be, for example, 0.20 or more, or less than 0.20. From the perspective of miniaturization of electronic components, the magnetic permeability μr' at a frequency of 100 MHz is preferably within the above-mentioned range, and from the perspective of low loss, the loss tangent tanδ at a frequency of 100 MHz is preferably within the above-mentioned range. The magnetic permeability μr' can be measured using a known magnetic permeability measuring device. The loss tangent tanδ can be calculated from the magnetic permeabilities μr' and μr" measured using a magnetic permeability measuring device.

[0084] Example

[0085] Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to the embodiments shown in the examples.

[0086] The physical properties of the magnetic particles described below are values measured by the following methods.

[0087] <Average particle size of magnetic particles>

[0088] The average particle size of each magnetic particle is a value measured by the previously described method using a scanning electron microscope (FE-SEM) FE-SEM S4800 manufactured by Hitachi, Ltd. and image analysis software KS-400 manufactured by Carl Zeiss.

[0089] <Coercive force Hc of magnetic particles>

[0090] The coercive force Hc of each magnetic particle was determined from a hysteresis curve (referred to as an "MH curve") obtained by measurement at a magnetic field intensity of 15,000 Oe using a vibrating sample magnetometer (manufactured by TOEI INDUSTRY CO., LTD.).

[0091] [Example 1]

[0092] <Preparation of coating liquid (magnetic resin composition)>

[0093] To a plastic bottle, 100 parts by mass of molybdenum permalloy alloy particles (average particle size: see Table 1, coercive force Hc: 7.0 Oe, Ni content: 79.8 mass%, Fe content: 16.2 mass%, Mo content: 3.9 mass%), 6 parts by mass of an epoxy resin (EXA-4816 manufactured by DIC Corporation, epoxy equivalent: see Table 1), 0.2 parts by mass of an imidazole-type curing agent (jERcure IBMI12 manufactured by Mitsubishi Chemical Corporation), 0.5 parts by mass of a dispersant (DISPERBYK-108 manufactured by BYK Japan KK) and 4 parts by mass of methyl ethyl ketone were added and mixed for 30 minutes using a vibration stirrer to prepare a coating liquid.

[0094] <Film Production>

[0095] The coating solution was applied to the release surface of a release-treated PET film (PET75TR manufactured by NIPPA Co., Ltd.) using a knife coater with a coating gap of 100 μm. The film was dried for 1 hour in a drying apparatus at an internal temperature of 80°C. It was then heated on a hot plate (set temperature: 120°C) for 10 minutes to form a partially cured film. This film was then peeled from the release-treated PET film and heated in an oven at an internal temperature of 150°C for 20 minutes to form a cured film.

[0096] <Measurement of magnetic permeability>

[0097] A rectangular sample of 2 mm × 10 mm in size was cut from the cured film, and the thickness was measured at 10 points using a micrometer. The arithmetic mean of the thickness was 30 μm. For the rectangular sample, the magnetic permeability (μr' and μr") at a frequency of 100 MHz was measured using a magnetic permeability measuring device per01 (manufactured by KEYCOM Corporation). The loss tangent tanδ was calculated from the measured magnetic permeability (μr' and μr").

[0098] <Measurement of Magnetic Particle Filling Rate and Porosity>

[0099] A cross-sectional observation sample was cut from the cured film using a microtome. A scanning electron microscope (FE-SEM) was used, FE-SEM S4800 manufactured by Hitachi, Ltd., and the filling rate and porosity of the magnetic particles were determined by the methods described above.

[0100] Observation of cracks

[0101] A film piece having a size of 2 cm×2 cm was cut from the cured film using a cutter, and the surface of the film piece was visually observed to check for the presence of cracks in the outer peripheral edge.

[0102] <Measurement of the magnetic permeability ratio before and after hydrochloric acid immersion>

[0103] A rectangular sample of 2 mm x 10 mm was cut from the cured film and its magnetic permeability (μr') was measured at a frequency of 100 MHz using a magnetic permeability measuring device per01 (manufactured by KEYCOM Corporation). The magnetic permeability measured here is referred to as "magnetic permeability before immersion."

[0104] The rectangular sample was then immersed in 10 g of 10% by mass hydrochloric acid for 30 minutes, removed, rinsed with water, and dried. The magnetic permeability (μr') at a frequency of 100 MHz was then measured in the same manner as above. The magnetic permeability measured here is referred to as the "post-immersion magnetic permeability."

[0105] The magnetic permeability ratio before and after hydrochloric acid immersion was calculated by the following formula: It can be said that the larger the calculated magnetic permeability ratio value is, the smaller the decrease in magnetic permeability in the acidic environment is.

[0106] Magnetic permeability ratio = [(magnetic permeability after immersion - 1) / (magnetic permeability before immersion - 1)] × 100

[0107] [Example 2]

[0108] The metal particles were changed to iron-based amorphous alloy particles (average particle size: refer to Table 1, coercive force Hc: 4.7 Oe, Fe content: 87.2 mass%, Si content: 6.8 mass%, Cr content: 2.5 mass%, B content: 2.5 mass%). Except for this, the preparation of the cured film and various measurements were carried out in the same manner as Example 1.

[0109] [Example 3]

[0110] The metal particles were changed to molybdenum permalloy alloy particles (average particle size: refer to Table 1, coercive force Hc: 8.1Oe, Ni content: 79.8 mass%, Fe content: 16.2 mass%, Mo content: 3.9 mass%). Except for this, the preparation of the cured film and various measurements were carried out in the same manner as in Example 1.

[0111] [Example 4]

[0112] Preparation of a cured film and various measurements were performed in the same manner as in Example 1, except that 6 parts by mass of Ni—Zn ferrite particles (average particle size and coercive force: see Table 1) were added when preparing the coating liquid.

[0113] [Example 5]

[0114] The metal particles were changed to molybdenum permalloy alloy particles (average particle size: refer to Table 1, coercive force Hc: 6.2Oe, Ni content: 79.8 mass%, Fe content: 16.2 mass%, Mo content: 3.9 mass%). Except for this, the preparation of the cured film and various measurements were carried out in the same manner as in Example 1.

[0115] [Example 6]

[0116] Preparation of a cured thin film and various measurements were performed in the same manner as in Example 4, except that Ni—Zn ferrite particles having the average particle size and coercive force shown in Table 1 were used.

[0117] [Example 7]

[0118] Preparation of a cured thin film and various measurements were performed in the same manner as in Example 4, except that Ni—Zn ferrite particles having the average particle size and coercive force shown in Table 1 were used.

[0119] [Example 8]

[0120] The metal particles were changed to iron-based amorphous alloy particles (average particle size: refer to Table 1, coercive force Hc: 4.7 Oe, Fe content: 87.2 mass%, Si content: 6.8 mass%, Cr content: 2.5 mass%, B content: 2.5 mass%). Except for this, the preparation of the cured film and various measurements were carried out in the same manner as Example 4.

[0121] [Example 9]

[0122] The preparation of the cured film and various measurements were carried out in the same manner as in Example 4, except that the metal particles were changed to iron-nickel alloy particles (average particle size: see Table 1, coercive force Hc: 12.3 Oe, Fe content: 49.5 mass %, Ni content: 50.3 mass %).

[0123] [Example 10]

[0124] Preparation of a cured film and various measurements were carried out in the same manner as in Example 4, except that the epoxy resin was changed to JER871 manufactured by Mitsubishi Chemical Corporation (epoxy equivalent: see Table 1).

[0125] [Example 11]

[0126] The metal particles were changed to molybdenum permalloy alloy particles (average particle size: refer to Table 1, coercive force Hc: 8.1Oe, Ni content: 79.8 mass%, iron content: 16.2 mass%, molybdenum content: 3.9 mass%). Except for this, the preparation of the cured film and various measurements were carried out in the same manner as Example 4.

[0127] [Comparative Example 1]

[0128] Preparation of a cured thin film and various measurements were performed in the same manner as in Example 4, except that Ni—Zn ferrite particles having the average particle size and coercive force shown in Table 1 were used.

[0129] [Comparative Example 2]

[0130] Preparation of a cured thin film and various measurements were performed in the same manner as in Example 4, except that Ni—Zn ferrite particles having the average particle size and coercive force shown in Table 1 were used.

[0131] [Comparative Example 3]

[0132] Preparation of a cured film and various measurements were carried out in the same manner as in Example 2, except that no dispersant was used when preparing the coating liquid.

[0133] [Comparative Example 4]

[0134] Preparation of a cured film and various measurements were carried out in the same manner as in Example 4, except that the epoxy resin was changed to JER827 manufactured by Mitsubishi Chemical Corporation (epoxy equivalent: see Table 1).

[0135] [Comparative Example 5]

[0136] Preparation of a cured film and various measurements were carried out in the same manner as in Example 4, except that the epoxy resin was changed to JER152 manufactured by Mitsubishi Chemical Corporation (epoxy equivalent: see Table 1).

[0137] The above results are shown in Table 1 (Table 1-1 to Table 1-3).

[0138]

[0139]

[0140]

[0141] From the results shown in Table 1, it was confirmed that the magnetic resin composition of the example can form a cured product having a high magnetic permeability μr′ in a high frequency band (100 MHz) and suppressing the occurrence of cracks during processing.

[0142] Industrial applicability

[0143] One embodiment of the present invention is useful in the technical field of various electronic components.

Claims

1. A magnetic resin composition comprising: magnetic particles; and An epoxy resin having an epoxy equivalent weight of 400 g / eq or more, and The filling rate of the magnetic particles is 70% or more based on the area. The magnetic particles include metal particles and ferrite particles, wherein the content of the ferrite particles is 1 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the metal particles. The average particle size of the metal particles is greater than 4.0 μm and less than 10.0 μm, and the average particle size of the ferrite particles is greater than 0.1 μm and less than 1.0 μm. The coercive force of the metal particles is 50.0 Oe or less, and the coercive force of the ferrite particles is 50.0 Oe or less. 2 . The magnetic resin composition according to claim 1 , wherein the porosity is less than 0.30% on an area basis.

3. The magnetic resin composition according to claim 1 or 2, wherein The metal particles include Ni and Fe.

4. The magnetic resin composition according to claim 3, wherein The metal particles further contain Mo.

5. The magnetic resin composition according to claim 1 or 2, wherein The ferrite particles have a coercive force Hc of 30.0 Oe or more and 50.0 Oe or less. 6 . A cured product obtained by curing the magnetic resin composition according to claim 1 . 7 . An electronic component comprising the cured product according to claim 6 .

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