Compound, molded body, cured product of compound, magnetic core, and coil component

Abstract

Provided is a compound that has excellent fluidity and suppresses magnetic loss of a magnetic core that contains a cured product of the compound. The compound contains a metal powder and a resin composition. The metal powder is a soft magnetic material. The resin composition contains a thermosetting resin. The metal powder includes a plurality of submicron particles and a plurality of large particles that have a larger particle diameter than the plurality of submicron particles. The content of the plurality of submicron particles in the metal powder is represented by V1 vol%. The content of the plurality of large particles in the metal powder is represented by V2 vol%. V2 / V1 is 29 to 59 inclusive.

Description

Compounds, molded products, cured compound products, magnetic cores, and coil components

[0001] This disclosure relates to compounds, molded articles, cured products of compounds, magnetic cores, and coil components.

[0002] Compounds containing soft magnetic metal powder and electrically insulating resin compositions (such as thermosetting resins) are used as raw materials for various industrial products. (See Patent Document 1 below.) For example, compounds are used as raw materials for inductors, reactors, transformers, motor stators, motor yokes, power modules, thyristor valves, noise filters (EMI filters), choke coils, and solenoid cores. Compounds are also used as encapsulants for electronic equipment such as semiconductors or electronic circuit boards.

[0003] International Publication No. 2020 / 075745

[0004] For example, coil components such as inductors contain a magnetic core made of a hardened compound, with the magnetic core positioned inside the coil and the coil sealed within the hardened compound. The manufacture of coil components requires the molding of the compound (e.g., transfer molding), and the compound's fluidity is required for this molding. If the compound lacks fluidity, it is difficult to supply the compound evenly into the mold, making compound molding difficult, and it becomes difficult to precisely adjust the shape and dimensions of the magnetic core and coil components based on the shape and dimensions of the mold.

[0005] Magnetic loss in a magnetic core reduces the energy efficiency of electrical or electronic equipment using coil components. Therefore, it is desirable to suppress magnetic loss in the magnetic core for coil components (especially coil components that operate in the high-frequency band). Suppression of magnetic loss can be rephrased as a reduction in the magnetic loss coefficient. The magnetic loss coefficient is denoted as tanδ. tanδ (unit: none) may be defined as μ'' / μ'. μ'' (unit: none) is the imaginary part of the complex relative permeability of the magnetic core including the hardened compound, and μ' (unit: none) is the real part of the complex relative permeability of the magnetic core including the hardened compound.

[0006] One aspect of this disclosure is to provide a compound that exhibits excellent fluidity and suppresses magnetic loss in a magnetic core containing a cured compound, a molded article containing the compound, a cured compound, a magnetic core containing a cured compound, and a coil component containing a magnetic core.

[0007] For example, one aspect of this disclosure relates to a compound described in any one of the following [1] to [3], a molded article described in [4], a cured product of the compound described in [5], a magnetic core described in [6], and a coil component described in [7].

[0008] [1] A compound comprising a metal powder and a resin composition, wherein the metal powder is a soft magnetic material, the resin composition comprises a thermosetting resin, the metal powder comprises a plurality of submicron particles and a plurality of large particles having a particle size larger than the particle size of the plurality of submicron particles, the content of the plurality of submicron particles in the metal powder is expressed as V1 volume%, the content of the plurality of large particles in the metal powder is expressed as V2 volume%, and V2 / V1 is 29 or more and 59 or less.

[0009] [2] The compound according to [1], wherein the D50 of the metal powder is 5.5 μm or less.

[0010] [3] The compound described in [1] or [2], which is a raw material for the magnetic core.

[0011] [4] A molded article comprising the compound described in any one of [1] to [3].

[0012] [5] A cured compound according to any one of [1] to [3].

[0013] [6] A magnetic core containing the cured material described in [5].

[0014] [7] A coil component comprising the magnetic core described in [6] and a coil, wherein the magnetic core is positioned inside the coil.

[0015] According to one aspect of this disclosure, a compound is provided that has excellent fluidity and suppresses magnetic loss in a magnetic core including a cured compound; a molded article containing the compound; a cured compound; a magnetic core including a cured compound; and a coil component including a magnetic core.

[0016] Figure 1 is a schematic perspective view of a specific example of a coil component (inductor). Figure 2 is a schematic cross-sectional view of the coil component shown in Figure 1, and the cross-section shown in Figure 2 includes the central axis of the coil and crosses the pair of terminal electrodes that the coil component has.

[0017] Preferred embodiments of the present disclosure will be described below with reference to the drawings. In the drawings, equivalent components are denoted by equivalent reference numerals. The present disclosure is not limited to the embodiments described below. In the present disclosure, relative permeability means both the relative permeability of the compound and the relative permeability of the cured product of the compound (e.g., the magnetic core).

[0018] (Overview of Compound, Molded Article, Cured Compound, Magnetic Core, and Coil Component) The compound according to this embodiment comprises a metal powder and a resin composition. The compound may be solid at room temperature (e.g., 20 ± 15°C). For example, the compound may be a powder or tablet at room temperature. The compound may be a paste further containing an organic solvent in addition to the metal powder and resin composition. The metal powder and resin composition in the compound may be mixed. In other words, the compound may be rephrased as a mixture containing the metal powder and the resin composition. The metal powder consists of a plurality of metal particles. The metal powder is a soft magnetic material. The metal powder may be rephrased as a metal filler. The resin composition contains a thermosetting resin. The resin composition has electrical insulating properties. The resin composition may be rephrased as a thermosetting binder (adhesive). The compound may contain either or both of the following: an uncured resin composition (uncured resin composition) and a semi-cured resin composition (semi-cured resin composition, i.e., a B-stage resin composition). The compound may consist only of metal powder and resin composition. The compound may further contain other components in addition to the metal powder and resin composition.

[0019] The surface of some or all of the multiple metal particles constituting the metal powder may be covered with a resin composition. The compound may contain one or more metal particles that are not covered with a resin composition. The compound may contain one or more particles consisting solely of a resin composition. The compound may contain one or more composite particles (granules) consisting of one or more metal particles constituting the metal powder and a resin composition covering one or more metal particles. One composite particle may consist of multiple metal particles bound together via a resin composition.

[0020] The molded article according to this embodiment includes the compound described above. The molded article according to this embodiment may consist only of the compound. The molded article may also include other components such as coils in addition to the compound. The molded article may include one or both of the uncured resin composition and the semi-cured resin composition. The cured compound according to this embodiment includes the cured resin composition (C-stage resin composition). In a molded article containing the compound, or in a cured compound, the resin composition or its cured product binds a plurality of metal particles together. Furthermore, the resin composition or its cured product interposed between adjacent plurality of metal particles electrically insulates the plurality of metal particles. Furthermore, the resin composition or its cured product interposed between adjacent plurality of metal particles suppresses magnetic saturation of the compound or its cured product and suppresses a decrease in the magnetic permeability of the compound or its cured product.

[0021] For example, the compound may be the raw material for a coil component. For example, the coil component may include a cured compound and a coil. For example, the compound may be the raw material for a magnetic core (e.g., a compacted magnetic core) included in the coil component. That is, the magnetic core may include a cured compound. The magnetic core may consist only of a cured compound. The structure of the coil component is not limited. For example, as shown in Figures 1 and 2, the coil component 1 (e.g., an inductor) may include a cured compound 2 and a coil 5, the coil 5 may be sealed in the cured compound 2, and the magnetic core 2dc containing the cured compound 2 may be arranged inside the coil 5. The coil component 1 may further include a pair of terminal electrodes 3, one of which may be located on one end face of the coil component 1 and the other terminal electrode 3 on the other end face of the coil component 1. One end of the coil 5 (the lead-out portion 5a) may be connected to one terminal electrode 3, and the other end of the coil 5 (the lead-out portion 5b) may be connected to the other terminal electrode 3.

[0022] The metal powder contains a plurality of submicron particles and a plurality of larger particles having a particle size larger than that of the plurality of submicron particles. The metal powder may consist only of the plurality of submicron particles and the plurality of larger particles. The content of the plurality of submicron particles in the metal powder is expressed as V1 volume%. The content of the plurality of larger particles in the metal powder is expressed as V2 volume%. V2 / V1 is between 29 and 59. For example, the units of V1 and V2 are cc and cm. ３ , or m ３It may be. V1 + V2 may be 100. When V2 / V1 is between 29 and 59, the compound has excellent fluidity, and the magnetic loss of the magnetic core containing the hardened compound is suppressed. The smaller V2 / V1, the greater the content of multiple submicron particles in the metal powder. The greater the content of multiple submicron particles in the metal powder, the larger the specific surface area of ​​the metal powder, making the metal powder in the compound more prone to agglomeration and making the compound less fluid. In other words, the smaller V2 / V1, the less fluid the compound becomes. In particular, when V2 / V1 is less than 29, the compound is less fluid. The larger V2 / V1, the greater the content of multiple large particles in the metal powder. Since the eddy currents generated on the surface of each large particle in the magnetic core are greater than the eddy currents generated on the surface of each submicron particle in the magnetic core, the greater the content of multiple large particles in the metal powder, the greater the magnetic loss of the magnetic core. In other words, the larger V2 / V1, the greater the magnetic loss. In particular, when V2 / V1 is greater than 59, magnetic loss tends to increase. The relationship between the upper and lower limits of V2 / V1 and fluidity and magnetic loss was first discovered through multiple experiments conducted by the inventors and is demonstrated by the embodiments and comparative examples described later. To increase the inductance value of a coil component, a high relative permeability of the magnetic core containing the hardened compound is required. The compound according to this embodiment easily achieves a high relative permeability. Furthermore, the DC superposition characteristics of a coil component containing a magnetic core containing the hardened compound according to this embodiment are easily improved. DC superposition characteristics refer to the property that as the DC flowing through the coil component increases, the magnetic core reaches magnetic saturation, and as a result, the relative permeability of the magnetic core and the inductance value (unit: Henry, i.e., H) of the coil component decrease. Improving DC superposition characteristics means suppressing the decrease in relative permeability and inductance value that occurs with increasing DC flowing through the coil component. In other words, improving DC superposition characteristics means increasing the DC superposition rated current (saturation current) of the coil component. For example, the DC superimposed rated current (unit: amperes, i.e., A) is the DC current flowing through a coil component when the relative permeability or inductance value has decreased by 30% from its initial value, during the process of increasing DC current from zero A.

[0023] For example, the D50 (median diameter) of the metal powder may be 4.0 μm or more and 14.0 μm or less, or 4.8 μm or more and 13.8 μm or less. D50 may be defined as particle size X such that the proportion of metal powder with a particle size of particle size X or less among the metal powder contained in the compound is 50 volume percent. The smaller the D50 of the metal powder, the easier it is for eddy currents generated on the surface of each metal particle constituting the metal powder to decrease, and the easier it is for magnetic loss to be suppressed. For the reason that magnetic loss is easily suppressed, the D50 of the metal powder may be 5.5 μm or less, 4.0 μm or more and 5.5 μm or less, 4.8 μm or more and 5.5 μm or less, 4.0 μm or more and 5.4 μm or less, or 4.8 μm or more and 5.4 μm or less.

[0024] For example, the particle size of each of the multiple submicron particles may be between 0.1 μm and 1.0 μm. For example, the particle size of each of the multiple large particles may be greater than 1.0 μm and 100 μm or less.

[0025] For example, a metal powder with a V2 / V1 ratio of 29 to 59 may be produced by mixing a raw material powder with a high V2 / V1 ratio with another raw material powder with a low V2 / V1 ratio in a predetermined volume ratio or mass ratio. For example, a metal powder with a V2 / V1 ratio of 29 to 59 may be produced by mixing a raw material powder consisting only of a plurality of submicron particles with a raw material powder consisting only of a plurality of large particles. The V2 / V1 ratio of each raw material powder may be determined based on the particle size distribution of each raw material powder based on its volume. The particle size distribution of each raw material powder (for example, at least one of the average particle size and the upper limit of the particle size) may be freely adjusted by classifying each raw material powder using one or more sieves with predetermined mesh openings (e.g., cutoff). The particle size distribution of each raw material powder may be adjusted by a pulverizer such as a ball mill and a bead mill, or by an air classifier. For example, each raw material powder used to produce the metal powder may be produced by a water atomization method, a gas atomization method, a pulverization method, or a liquid-phase synthesis method. The V2 / V1 and D50 of the metal powder may be calculated from the particle size distribution of the metal powder based on its volume. That is, the horizontal axis of the particle size distribution may be the particle size of each metal particle constituting the metal powder, and the vertical axis may be the cumulative volume of one or more metal particles. For example, the particle size of each metal particle may be the maximum width of each metal particle. For example, the particle size of each metal particle may be the diameter of a sphere with the same volume as each metal particle (equivalent diameter of an equivolute sphere). For example, the particle size of each metal particle may be the diameter of a sphere with the same surface area as each metal particle (equivalent diameter of an equisurface area sphere). For example, the particle size of each metal particle may be the diameter of a sphere with the same settling velocity and density as each metal particle (equivalent diameter of an equisettling velocity sphere, or Stokes diameter). For example, the particle size distribution of the raw material powder and the metal powder may be measured by laser diffraction scattering, sieving tests, dynamic light scattering, centrifugal sedimentation, or particle trajectory analysis. The shape of the metal powder (each metal particle) is not particularly limited. For example, the shape of the metal powder (each metal particle) may be spherical, nearly spherical, flat, needle-shaped, or irregular.

[0026] The content of metal powder in the compound is not particularly limited. For example, the content of metal powder in the compound may be 90% by mass or more but less than 100% by mass, 92.0% by mass or more but 98.0% by mass or less, 92.0% by mass or more but 96.0% by mass or less, or 92.0% by mass or more but 95.0% by mass or less. The content of resin composition in the compound is also not particularly limited. For example, the content of resin composition in the compound may be greater than 0% by mass and 10% by mass or less, 2.0% by mass or more but 8.0% by mass or less, 4.0% by mass or more but 8.0% by mass or less, or 5.0% by mass or more but 8.0% by mass or less. The higher the content of metal powder in the compound, the higher the relative permeability of the cured compound. In other words, the lower the content of resin composition in the compound, the higher the relative permeability of the cured compound. The lower the metal powder content in the compound, the more fluid the compound becomes, and the higher the mechanical strength of the cured compound. In other words, the higher the resin composition content in the compound, the more fluid the compound becomes, and the higher the mechanical strength of the cured compound. For the reasons that the compound becomes more fluid and its magnetic permeability increases easily, the metal powder content of the compound may be 92.0% by mass or more and 96.0% by mass or less, or 92.0% by mass or more and 95.0% by mass or less, and the resin composition content of the compound may be 4.0% by mass or more and 8.0% by mass or less, or 5.0% by mass or more and 8.0% by mass or less.

[0027] For example, the content of each of the metal powder and the resin composition in the compound may be specified by the following method based on the specific gravity of each of the compound, the metal powder, and the resin composition. The specific gravity (unit: none) may be the ratio of the density of each of the compound, the metal powder, and the resin composition to the density of a standard substance (for example, the density of water at 4°C). For example, the specific gravity of each of the compound, the metal powder, and the resin composition may be measured by a general method (such as the water displacement method) based on Archimedes' principle. The specific gravity of each of the metal powder and the resin composition may be measured in advance before the production of the compound. Using an inert organic solvent that does not react with the metal powder and the resin composition, the compound may be separated into the metal powder and the resin composition (organic substances dissolved in the organic solvent), and the specific gravity of each of the separated metal powder and resin composition may also be measured. The specific gravity of the metal powder is S Ｍ and may be represented as such. The content of the metal powder in the compound may be represented as α mass%. The specific gravity of the resin composition is S Ｒ and may be represented as such. The content of the resin composition in the compound may be represented as (100 - α) mass%. The specific gravity S Ｃ of the compound may be represented by the following Formula 1. Based on the following Formula 1, the content α of the metal powder in the compound may be calculated from the measured specific gravities (S Ｍ , S Ｒ , and S Ｃ ). S Ｃ = [(S Ｍ ×α) + {S Ｒ ×(100 - α)}] / 100 (1)

[0028] (Specific Examples of Metal Powders) As long as the metal powder is a soft magnetic material, the composition of the metal powder (each of the multiple metal particles) is not particularly limited. For example, the metal powder may contain iron. In addition to iron, the metal powder may further contain at least one metal element selected from the group consisting of base metal elements, noble metal elements, transition metal elements, and rare earth elements. For example, the metal element other than iron contained in the metal powder may be at least one element selected from the group consisting of cobalt (Co), nickel (Ni), copper (Cu), titanium (Ti), manganese (Mn), zinc (Zn), aluminum (Al), tin (Sn), arsenic (As), antimony (Sb), chromium (Cr), beryllium (Be), barium (Ba), strontium (Sr), lead (Pb), bismuth (Bi), silver (Ag), niobium (Nb), hafnium (Hf), zirconium (Zr), tantalum (Ta), molybdenum (Mo), tungsten (W), and vanadium (V). The metal powder may contain nonmetallic elements in addition to metallic elements. For example, the nonmetallic elements contained in the metal powder may be at least one element selected from the group consisting of boron (B), carbon (C), nitrogen (N), oxygen (O), silicon (Si), phosphorus (P), and sulfur (S). For example, if the metal powder (e.g., multiple large particles) contains Cr, oxidation of the metal powder is easily suppressed, the metal powder is less likely to rust, and the decrease in relative permeability is easily suppressed. The composition of multiple submicron particles may be the same as that of multiple large particles. The composition of multiple large particles may be different as well. The composition of multiple submicron particles may be the same as that of multiple large particles. The composition of multiple submicron particles may be different as well as that of multiple large particles.

[0029] The metal powder may contain at least one metal from among pure iron and iron-containing alloys (iron-based alloys). The metal powder may consist only of pure iron. The metal powder may consist only of iron-based alloys. The metal powder may consist only of pure iron and iron-based alloys. For example, the pure iron may be carbonyl iron powder. Carbonyl iron powder is Fe(CO) ５This is a perfectly spherical pure iron powder obtained by the reduction (thermal decomposition) of (ferrous iron pentacarbonyl). For example, the iron-based alloy contained in the metal powder may be at least one alloy selected from the group consisting of Fe-Cr-Si alloys, Fe-Cr alloys, Fe-Si alloys, Fe-Si-Al alloys, Fe-Ni alloys, Fe-Cu-Ni alloys, Fe-Co alloys, and Fe-Ni-Cr alloys. The iron or iron-based alloy contained in the metal powder may be crystalline or amorphous. The metal powder may contain metal nanocrystals. For example, the metal powder may contain a plurality of amorphous particles including an amorphous alloy, and the average particle size of the plurality of amorphous particles may be 2 μm or more and 12 μm or less. A plurality of amorphous particles with an average particle size of 2 μm or more and 12 μm or less are more effective at reducing iron loss in the magnetic core (in other words, core loss) than a plurality of crystalline particles (for example, a plurality of crystalline particles including nanocrystals).

[0030] Some or all of the multiple metal particles constituting the metal powder may be covered with an insulating coating. Some or all of the surface of each metal particle may be covered with an insulating coating. Covering the metal powder with an insulating coating improves the electrical insulation of the compound. If the insulating coating contains glass, the surface of the insulating coating tends to become smoother, and friction between multiple metal particles tends to be suppressed. As a result, aggregation (blocking) of the compound tends to be suppressed, and the fluidity of the compound tends to be improved. Some or all of the surface of the insulating coating may be covered with a resin composition.

[0031] For example, insulating coatings include glass, phosphoric acid (phosphate), silica (SiO ２ ), iron oxide (Fe ２ O ３ ), and chromium oxide (Cr ２ O ３The insulating coating may contain at least one component selected from the group consisting of ) ). For example, in addition to silicon (Si), the glass may contain at least one element selected from the group consisting of oxygen (O), boron (B), sodium (Na), and aluminum (Al). For example, the glass may contain at least one component from silicate glass (silicate), phosphatesilicate glass (phosphate), and borosilicate glass (borosilicate). The composition of the insulating coating may be measured by at least one analytical method from photoelectron spectroscopy (XPS) and energy-dispersive X-ray analysis (EDX). The insulating coating may be formed by a wet method using an alkoxysilane solution, etc., or by a dry method such as mechanofusion. For example, the thickness of the insulating coating may be 10 nm or more and 200 nm or less. The thickness of the insulating coating may be measured in the cross-section of the metal particles by transmission electron microscopy (TEM) and EDX.

[0032] The compound may further contain a non-metallic filler in addition to the metal powder. For example, the compound may contain silica (SiO₂) as the non-metallic filler. ２ It may contain a filler (particulate filler) consisting of the following:

[0033] (Specific Examples of Resin Compositions) The resin composition may be the remaining portion of the compound excluding the metal powder (non-volatile component). As described above, the resin composition includes at least a thermosetting resin. In addition to the thermosetting resin, the resin composition may further include at least one component selected from the group consisting of a curing agent, a curing accelerator (curing catalyst), a coupling agent, a wax (release agent), and a flame retardant. Specific examples of each component are as follows.

[0034] The thermosetting resin contained in the resin composition may be at least one resin selected from the group consisting of an epoxy resin, a phenol resin, a bismaleimide resin, a polyimide resin, and a polyamideimide resin. The resin composition may further contain other resins (for example, thermoplastic resins) in addition to the thermosetting resin. For example, the resin composition may further contain at least one other resin selected from the group consisting of a polyphenylene sulfide resin, an acrylic resin, a methacrylic resin, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, and a silicone resin.

[0035] <Epoxy Resin and Curing Agent> The epoxy resin may be at least one resin selected from the group consisting of a biphenyl type epoxy resin, a stilbene type epoxy resin, a diphenylmethane type epoxy resin, a sulfur atom-containing type epoxy resin, a novolak type epoxy resin, a dicyclopentadiene type epoxy resin, a salicylaldehyde type epoxy resin, a copolymerization type epoxy resin of naphthols and phenols, an epoxidized product of an aralkyl type phenol resin, a bisphenol type epoxy resin, a glycidyl ether type epoxy resin of alcohols, a glycidyl ether type epoxy resin of a para-xylylene-modified phenol resin and / or a meta-xylylene-modified phenol resin, a glycidyl ether type epoxy resin of a terpene-modified phenol resin, a cyclopentadiene type epoxy resin, a glycidyl ether type epoxy resin of a polycyclic aromatic ring-modified phenol resin, a glycidyl ether type epoxy resin of a naphthalene ring-containing phenol resin, a glycidyl ester type epoxy resin, a glycidyl type or methyl glycidyl type epoxy resin, an alicyclic epoxy resin, a halogenated phenol novolak type epoxy resin, an ortho-cresol novolak type epoxy resin, a hydroquinone type epoxy resin, a trimethylolpropane type epoxy resin, and a linear aliphatic epoxy resin obtained by oxidizing an olefin bond with a peracid such as peracetic acid.

[0036] At least some of the epoxy resins may be naphthalene-type epoxy resins having a naphthalene structure. Naphthalene-type epoxy resins are solid at room temperature. When the compound contains a naphthalene-type epoxy resin, the product manufactured from the compound (cured compound) tends to have high mechanical strength at both room temperature and high temperatures. The naphthalene-type epoxy resin may be at least one resin selected from the group consisting of naphthalene diepoxy compounds, naphthylene ether-type epoxy resins, naphthalene novolac-type epoxy resins, methylene-bonded dimers of naphthalene diepoxy compounds, and methylene-bonded compounds of naphthalene monoepoxy compounds and naphthalene diepoxy compounds. The epoxy resin may also include a bifunctional epoxy resin. For example, the bifunctional epoxy resin may be at least one resin from among α-naphthol-type epoxy resins and β-naphthol-type epoxy resins.

[0037] The epoxy resin may contain at least one of the trifunctional epoxy resins and tetrafunctional epoxy resins. The naphthalene-type epoxy resin described above may be at least one of the trifunctional epoxy resins and tetrafunctional epoxy resins. A trifunctional epoxy resin is an epoxy resin composed of structural units having three epoxy groups. A tetrafunctional epoxy resin is an epoxy resin composed of structural units having four epoxy groups. When the epoxy resin contains at least one of the trifunctional epoxy resins and tetrafunctional epoxy resins, the epoxy resins are crosslinked three-dimensionally during the thermal curing process of the compound, forming a strong crosslinked network. As a result, the movement of the epoxy resin in the cured compound is easily suppressed at high temperatures. In other words, the glass transition temperatures of the trifunctional epoxy resins and tetrafunctional epoxy resins are higher than those of the difunctional epoxy resin. Therefore, when the epoxy resin contains at least one of the trifunctional epoxy resins and tetrafunctional epoxy resins, the cured compound tends to have high mechanical strength at high temperatures.

[0038] The compound may contain one of the epoxy resins listed above. The compound may contain multiple types of epoxy resins listed above.

[0039] Curing agents can be classified into those that cure epoxy resins in the range from low temperature to room temperature and heat-curing agents that cure epoxy resins with heating. For example, curing agents that cure epoxy resins in the range from low temperature to room temperature include aliphatic polyamines, polyaminoamides, and polymercaptans. For example, heat-curing agents include aromatic polyamines, acid anhydrides, phenol resins, phenol novolak resins, and dicyandiamide (DICY). From the perspective of improving the heat resistance (mechanical strength at high temperatures) of the cured product of the compound, the curing agent is preferably a heat-curing agent, more preferably a phenol resin, and even more preferably a phenol novolak resin.

[0040] Part or all of the curing agent may be a phenol resin. For example, the phenol resin may be at least one resin selected from the group consisting of aralkyl-type phenol resins, dicyclopentadiene-type phenol resins, salicylaldehyde-type phenol resins, novolak-type phenol resins, copolymer-type phenol resins of benzaldehyde-type phenol and aralkyl-type phenol, p-xylylene and / or m-xylylene-modified phenol resins, melamine-modified phenol resins, terpene-modified phenol resins, dicyclopentadiene-type naphthol resins, cyclopentadiene-modified phenol resins, polycyclic aromatic ring-modified phenol resins, biphenyl-type phenol resins, and triphenylmethane-type phenol resins. The phenol resin may be a copolymer composed of two or more of the above phenol resins.

[0041] The phenol novolac resin may be a resin obtained by condensing or co-condensing phenols and / or naphthols with aldehydes under an acidic catalyst. The phenols constituting the phenol novolac resin may be at least one selected from the group consisting of phenol, cresol, xylenol, resorcinol, catechol, bisphenol A, bisphenol F, phenylphenol, and aminophenol. The naphthols constituting the phenol novolac resin may be at least one selected from the group consisting of α-naphthol, β-naphthol, and dihydroxynaphthalene. The aldehydes constituting the phenol novolac resin may be at least one selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde.

[0042] The curing agent may be a compound having two phenolic hydroxyl groups in one molecule. For example, the compound having two phenolic hydroxyl groups in one molecule may be at least one compound selected from the group consisting of resorcinol, catechol, bisphenol A, bisphenol F, and substituted or unsubstituted biphenols.

[0043] The compound may contain one of the above-mentioned phenolic resins as a curing agent. The compound may contain multiple of the above-mentioned phenolic resins as a curing agent.

[0044] The ratio of hydroxyl group equivalents of phenolic resin to epoxy equivalents of epoxy resin may be between 0.5 and 1.5. In other words, the ratio of active groups (phenolic OH groups) in phenolic resin that react with epoxy groups in epoxy resin may be between 0.5 and 1.5 equivalents per equivalent of epoxy groups in epoxy resin.

[0045] <Curing Accelerator> The curing accelerator (curing catalyst) may be any composition that reacts with the epoxy resin to accelerate its curing, and is not limited to any other composition. For example, the curing accelerator may be a urea compound. The curing accelerator may also be an alkyl-substituted imidazole or an imidazole such as benzimidazole. The curing accelerator may also be a phosphorus-based curing accelerator. The compound may contain one type of curing accelerator. The compound may contain multiple types of curing accelerators.

[0046] The amount of curing accelerator added is not particularly limited. From the viewpoint of improving the curability and fluidity of the epoxy resin when it absorbs moisture, the amount of curing accelerator added may be 0.1 parts by mass or more and 30 parts by mass or less per 100 parts by mass of epoxy resin. The content of the curing accelerator may be 0.001 parts by mass or more and 5 parts by mass or less relative to the total mass of the epoxy resin and the curing agent (e.g., phenolic resin).

[0047] <Coupling Agent> The coupling agent may be a coupling agent that reacts with glycidyl groups present in a resin composition such as epoxy resin. The coupling agent improves the adhesion between the metal powder and the resin composition and improves the mechanical strength of the cured compound. The coupling agent that reacts with glycidyl groups may be a silane compound (silane coupling agent). For example, the silane coupling agent may be at least one coupling agent selected from the group consisting of epoxysilane, mercaptosilane, aminosilane, alkylsilane, ureidosilane, acid anhydride silane, methacrylicsilane, and vinylsilane. The compound may contain one of the above coupling agents. The compound may contain multiple types of the above coupling agents.

[0048] <Wax> The compound may contain wax. Wax may be rephrased as a lubricant or release agent. The inclusion of wax in the compound improves its fluidity and moldability, and improves its release properties. As a result, the accuracy of the shape and dimensions of the product manufactured from the compound (cured compound) is improved, and structural defects in the product are more easily suppressed. For example, the wax may be at least one compound from saturated fatty acids, saturated fatty acid salts, saturated fatty acid esters, and fatty acid amides. The wax may also be a synthetic wax. The compound may contain one of the above waxes. The compound may contain multiple types of the above waxes.

[0049] <Flame Retardants> The compound may contain flame retardants. For example, the flame retardant may be at least one compound selected from the group consisting of brominated flame retardants, phosphorus-based flame retardants, hydrated metal compound-based flame retardants, silicone-based flame retardants, nitrogen-containing compounds, hindered amine compounds, organometallic compounds, and aromatic engineering plastics. The compound may contain one of the above flame retardants, or more of the above flame retardants.

[0050] (Method for manufacturing the compound) The method for manufacturing the compound includes the step of preparing a mixed powder containing a metal powder and a resin composition.

[0051] For example, a mixed powder may be obtained by kneading a metal powder and each component constituting a resin composition while heating. A lump of mixed powder (aggregated mixed powder) may be obtained by heating and kneading the metal powder and the resin composition, and the mixed powder may be obtained by grinding the lump of mixed powder.

[0052] For example, the means for mixing the metal powder and the resin composition may be a kneader, rolls, or a stirrer. By heating and mixing the metal powder and the resin composition, the resin composition may coat part or all of the surface of each metal particle constituting the metal powder. By heating and mixing the metal powder and the resin composition, part or all of the resin composition may become a semi-cured product.

[0053] The metal powder and all the components constituting the resin composition may be kneaded together. A mixture of metal powder and a coupling agent may be prepared in advance, and this mixture may be kneaded with the other components of the resin composition. A mixture of each component of the resin composition, excluding the curing accelerator, and the metal powder may be prepared in advance, and this mixture may be kneaded with the curing accelerator. A mixture of each component of the resin composition, excluding the wax, and the metal powder may be prepared in advance, and this mixture may be kneaded with the wax.

[0054] The mixing time depends on the type of mixing means, the volume of the mixing means, and the amount of compound to be produced. The mixing time is not limited. For example, the mixing time may be between 1 minute and 20 minutes. For example, the temperature of the metal powder and resin composition during mixing (heating temperature) may be below the thermosetting temperature of the thermosetting resin. The heating temperature may be a temperature at which a semi-cured product of the thermosetting resin (B-stage resin composition) is formed and the formation of a cured product of the thermosetting resin (C-stage resin composition) is suppressed. The heating temperature may be lower than the activation temperature of the curing accelerator. For example, the heating temperature may be between 50°C and 150°C.

[0055] The method for preparing the mixed powder is not limited to the method described above. For example, a mixture may be obtained by kneading a metal powder, a resin composition, and an organic solvent while heating, and the mixed powder may be obtained by drying (and grinding) the mixture. When the organic solvent in which the resin composition is dissolved comes into contact with the surface of the metal particles, the metal particles are easily covered with the resin composition. For similar reasons, a mixture may be obtained by mixing the metal powder and the resin composition in an organic solvent, and the mixed powder may be obtained by drying (and grinding) the mixture. For example, the organic solvent may be at least one solvent selected from the group consisting of acetone, methyl ethyl ketone (2-butanone), methyl isobutyl ketone (4-methyl-2-pentanone), benzene, toluene, xylene, and N-methyl-2-pyrrolidone (NMP).

[0056] The above mixed powder itself may be used as a compound. A compound with an adjusted particle size distribution may be obtained by grinding the mixed powder. A compound with an adjusted particle size distribution may be obtained by classifying the mixed powder using a sieve. The above mixed liquid itself (i.e., paste) may be used as a compound.

[0057] (Methods for manufacturing molded articles, cured products, magnetic cores, and coil components) A molded article is obtained by molding the compound described above. By heat treatment of the molded article (thermosetting of the resin composition in the molded article), multiple metal particles are firmly bonded to each other by the cured resin composition, and a cured compound (e.g., a magnetic core) is obtained. For example, the method for molding the compound may be transfer molding, extrusion molding, or compression molding. Transfer molding is a type of injection molding. Transfer molding may be rephrased as pressure molding. Transfer molding may include the steps of heating the compound in a heating chamber to make it fluid, and supplying (pressure-injecting) the fluidized compound from the heating chamber into the mold through a casting runner. Depending on the industrial product (e.g., a coil component) to be manufactured using the compound, the dimensions and shape of the mold used for molding the compound may be selected. The heat treatment temperature of the molded article should be such that the resin composition in the molded article hardens sufficiently, and may be above the activation temperature of the curing accelerator. For example, the heat treatment temperature may be between 100°C and 300°C. For example, the heat treatment time may be between a few minutes and 10 hours. To suppress the oxidation of the metal powder in the molded article, the heat treatment of the molded article may be carried out under an inert atmosphere. A paste which is a mixture of the compound and an organic solvent may be used to manufacture a molded article containing the compound, a cured product of the compound, a magnetic core containing the cured product of the compound, and a coil component containing the magnetic core.

[0058] (Analysis Method) The composition of the compound used in the manufacture of the molded article and the cured product may be retrospectively analyzed by analyzing the samples obtained by crushing the molded article and the cured product, respectively. The sample may be dissolved in an organic solvent, and the metal powder may be separated from the resin composition dissolved in the organic solvent. The separated metal powder and resin composition may be analyzed individually. Even when the unused compound itself is analyzed directly, the separated metal powder and resin composition may be analyzed individually using the method described above. The method for measuring the particle size distribution of the metal powder may be as described above. For example, metal powders may be analyzed and identified by one or more analytical methods selected from the group consisting of X-ray fluorescence analysis (XRF), inductively coupled plasma (ICP) emission spectroscopy, X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS or EDX), and mass spectrometry (MS). For example, each component constituting the resin composition (such as a thermosetting resin) may be analyzed and identified by one or more analytical methods selected from the group consisting of infrared spectroscopy (IR), nuclear magnetic resonance (NMR), gas chromatography (GC), high-performance liquid chromatography (HPLC), and mass spectrometry.

[0059] This disclosure is not necessarily limited to the embodiments described above. Various modifications to this disclosure are possible and are included in this disclosure, without departing from the spirit of this disclosure.

[0060] For example, industrial products manufactured using the compound are not limited to inductors. Specific industrial products manufactured using the compound may include reactors, transformers, motor stators, motor yokes, power modules, thyristor valves, noise filters (EMI filters), choke coils, and solenoid cores.

[0061] The compound, the molded article containing the compound, or the cured product of the compound may be a encapsulant (for example, an encapsulant for electronic components). The compound can possess both the electrical insulation properties required for encapsulants for electronic or electrical equipment and the soft magnetic properties (electromagnetic shielding ability) required for electromagnetic shielding materials. For example, the compound, the molded article containing the compound, or the cured product of the compound may be an encapsulant (underfill, etc.) for semiconductor packages such as IC packages and LSI packages.

[0062] The present disclosure will be illustrated in detail by the following examples and comparative examples. The present disclosure is not limited to the following examples.

[0063] [Components included in the resin composition] The "Resin 1" described below is NC-3000 manufactured by Nippon Kayaku Co., Ltd., and is a biphenyl aralkyl type epoxy resin.

[0064] The "Resin 2" described below is TECHMORE VG-3101L manufactured by Printec Co., Ltd., and is a trifunctional epoxy resin that is a derivative of 1-[α-methyl-α-(4-hydroxyphenyl)ethyl]-4-[α,α-bis(4-hydroxyphenyl)ethyl]benzene.

[0065] The "curing agent 1" described below was HE910 manufactured by Air Water Performance Chemical Co., Ltd., and was a triphenylmethane-type phenolic resin.

[0066] The "curing agent 2" described below was MEHC7841 manufactured by UBE Corporation (formerly Meiwa Kasei Co., Ltd.), and was a biphenyl aralkyl type phenolic resin. The "curing agent 3" described below was MEHC7851 manufactured by UBE Corporation (formerly Meiwa Kasei Co., Ltd.), and was a biphenyl aralkyl type phenolic resin. The hydroxyl group equivalent of curing agent 2 was smaller than that of curing agent 3.

[0067] The "curing agent 4" described below was MEW-1800 manufactured by UBE Corporation (formerly Meiwa Chemicals Co., Ltd.), and was a phenol novolac resin.

[0068] The "curing accelerator" described below was U-CAT3512T manufactured by Sunapro Co., Ltd., and was an aromatic dimethylurea.

[0069] The "coupling agent" described below was KBM-5803, manufactured by Shin-Etsu Chemical Co., Ltd., and was 8-methacryloxyoctyltrimethoxysilane.

[0070] The "release agent 1" described below was Licowax OP manufactured by Clariant Chemicals Co., Ltd., which was a montanic acid ester partially saponified with calcium hydroxide.

[0071] The "release agent 2" described below was zinc stearate.

[0072] [Components contained in the metal powder] The "Powder 1" described below is 9A4-03 manufactured by Epson Atomics Corporation, and is a metal (soft magnetic material) composed of Fe, Si, and B. Powder 1 was amorphous. The cutoff diameter of Powder 1 was 53 μm. In other words, particles with a particle size (maximum particle width) larger than 53 μm were removed from Powder 1 by sieving. The average particle size of Powder 1 was 23 μm. The proportion of multiple submicron particles in Powder 1 was zero by volume.

[0073] The "Powder 2" described below was AW2-08 manufactured by Epson Atomics Corporation, and was a metal (soft magnetic material) composed of Fe, Si, Cr, and B. Powder 2 was amorphous. The average particle size of Powder 2 was adjusted to 12 μm. The proportion of multiple submicron particles in Powder 2 was 0.01% by volume.

[0074] The "Powder 3" described below was AW2-08 manufactured by Epson Atomics Corporation, and was a metal (soft magnetic material) composed of Fe, Si, Cr, and B. Powder 3 was amorphous. The average particle size of Powder 3 was adjusted to 5.5 μm. The proportion of multiple submicron particles in Powder 3 was 0.03 volume%.

[0075] The "Powder 4" described below was AW2-08 manufactured by Epson Atomics Corporation, and was a metal (soft magnetic material) composed of Fe, Si, Cr, and B. Powder 4 was amorphous. The average particle size of Powder 4 was adjusted to 3.5 μm. The proportion of multiple submicron particles in Powder 4 was 1.67 volume%.

[0076] The "powder 5" described below was SAP-2C manufactured by Shinto Kogyo Co., Ltd., and was a metal (soft magnetic material) composed of Fe, Si, Cr, and B. Powder 5 was amorphous. The average particle size of powder 5 was 2.0 μm. The proportion of multiple submicron particles in powder 5 was 8.3% by volume.

[0077] The "powder 6" described below was SAP-2 manufactured by Shinto Kogyo Co., Ltd., and was a metal (soft magnetic material) composed of Fe, Si, Cr, and B. The average particle size of powder 6 was 2.0 μm. The proportion of multiple submicron particles in powder 6 was 10.3% by volume.

[0078] The "Powder 7" described below was HQ-I manufactured by BASF Japan Ltd., and was a carbonyl iron powder (soft magnetic material). The average particle size of Powder 7 was 2.0 μm. The proportion of multiple submicron particles in Powder 7 was 10.0% by volume.

[0079] (Example 1) The resin composition of Example 1 was a mixture consisting of resin 1, resin 2, curing agents 1 to 4, curing accelerator, coupling agent, and release agents 1 and 2. The mass ratio (in parts by mass) of resin 1, resin 2, curing agents 1 to 4, curing accelerator, coupling agent, and release agents 1 and 2 in the resin composition was adjusted to the values ​​shown in Table 1 below.

[0080] The metal powder of Example 1 was prepared by mixing powder 2 and powder 6. Based on the particle size distribution of powder 2 and powder 6, and the mixing ratio of powder 2 and powder 6, the V2 / V1 and D50 of the metal powder were adjusted to the desired values. The content of powder 2 and powder 6 in the metal powder (unit: mass%) was adjusted to the values ​​shown in Table 2 below. The V2 / V1 (unit: none) and D50 (unit: μm) of the metal powder are shown in Table 3 below. V2 / V1 and D50 were determined based on the particle size distribution of the metal powder based on volume. The particle size distribution was measured by laser diffraction scattering.

[0081] A compound (powder) consisting solely of metal powder and resin composition was obtained by kneading all the raw materials, which consisted of the components of the resin composition and metal powder, while heating. The maximum temperature of all the raw materials during kneading was 130°C. The content α (unit: mass%) of metal powder in the compound was adjusted to the value shown in Table 3 below. In other words, the content of resin composition in the compound was adjusted to (100 - α) mass%.

[0082] <Spiral Flow> The compound was placed in a transfer molding machine equipped with a mold. The spiral flow of the compound was measured at a mold temperature of 175°C, an injection pressure of 6.9 MPa, and a molding time of 120 seconds. Spiral flow is the length of the compound flow within the groove formed in the mold. In other words, spiral flow is the flow distance of the softened or liquefied compound. The shape of the groove through which the compound flows is a spiral curve (Archimedes' spiral). The easier the compound flows, the greater the spiral flow. A 100KN transfer molding machine (PZ-10 type) manufactured by Kodaira Seisakusho Co., Ltd. was used as the transfer molding machine. A mold conforming to ASTM D3123 was used as the mold. The spiral flow (unit: cm) for Example 1 is shown in Table 3 below. In Table 3 below, spiral flow is denoted as "SF". The more fluid the compound, the greater the spiral flow.

[0083] <Measurement of Relative Permeability> A toroidal core (powder magnetic core) made of the cured compound was obtained by transfer molding of the compound at 175°C and post-curing (heating at 175°C for 5.5 hours) following the transfer molding. The pressure applied to the compound during transfer molding was 6.9 MPa. The dimensions of the toroidal core were 20 mm outer diameter x 12 mm inner diameter x 2 mm thickness.

[0084] The relative permeability of the toroidal core was measured. An impedance analyzer (product name: E4990A) manufactured by Keysight Technologies, Inc. was used for the measurement. The frequency during the measurement was 1 MHz. The relative permeability (unit: none) is shown in Table 3 below. A relative permeability of 10 or higher is desirable.

[0085] <Measurement of Magnetic Loss Coefficient> The complex relative permeability of the above toroidal core was measured at room temperature. The complex permeability was measured using the S-parameter method with a Vector Network Analyzer (VNA). A coaxial tube having a structure and dimensions that could accommodate the sample (toroidal core) was connected to the VNA, and the impedance was first measured without the sample. Next, the impedance was measured with the sample fitted into the coaxial tube. The AC frequency during impedance measurement in each state was 1 MHz. Based on the dimensions of the coaxial tube and the sample, and the change in impedance depending on the presence or absence of the sample, the complex relative permeability of the sample, the imaginary part μ'' of the complex relative permeability, the real part μ' of the complex relative permeability of the magnetic composite material, and the magnetic loss coefficient tanδ (i.e., μ'' / μ') were calculated. The tanδ (unit: none) at 1 MHz is shown in Table 3 below. The tanδ at each AC frequency was measured using the same method as described above, except that the AC frequency was changed to 10 MHz, 20 MHz, and 100 MHz. The tanδ at each AC frequency is shown in Table 3 below. In particular, it is preferable that the tanδ at 100 MHz is less than 0.2.

[0086] (Examples 2-9, Comparative Examples 1 and 2) The mass ratios (in parts by mass) of resin 1, resin 2, curing agents 1-4, curing accelerator, coupling agent, and release agents 1 and 2 in the resin compositions of Examples 2-9 and Comparative Examples 1 and 2 were adjusted to the values ​​shown in Table 1 below.

[0087] The metal powders in Examples 2-9 and Comparative Examples 1 and 2 were prepared by mixing two types of powders selected from the group consisting of powders 1 to 7. The content (in mass %) of powders 1 to 7 in the metal powders of Examples 2-9 and Comparative Examples 1 and 2 was adjusted to the values ​​shown in Table 2 below. The V2 / V1 ratio of the metal powders in Examples 2-9 and Comparative Examples 1 and 2 was adjusted to the values ​​shown in Table 3 below. The D50 ratio of the metal powders in Examples 2-9 and Comparative Examples 1 and 2 was adjusted to the values ​​shown in Table 3 below. The content α of the metal powder in the compounds of Examples 2-9 and Comparative Examples 1 and 2 was adjusted to the values ​​shown in Table 3 below.

[0088] Compounds for Examples 2-9 and Comparative Examples 1 and 2 were prepared in the same manner as in Example 1, except for the matters described above. The spiral flow of each of Examples 2-9 and Comparative Examples 1 and 2 was measured in the same manner as in Example 1. The spiral flows of each of Examples 2-9 and Comparative Examples 1 and 2 are shown in Table 3 below.

[0089] The relative permeability and tanδ of Examples 2-9 and Comparative Example 1 were measured using the same method as in Example 1. The relative permeability and tanδ of Examples 2-9 and Comparative Example 1 are shown in Table 3 below. However, since the compound of Comparative Example 2 had poor fluidity, it was not possible to produce a toroidal core by molding the compound of Comparative Example 2. Therefore, it was not possible to measure the relative permeability and tanδ of Comparative Example 2.

[0090]

[0091]

[0092]

[0093] For example, a compound relating to one aspect of this disclosure may be used as a raw material for a magnetic core contained in an inductor.

[0094] 1... Coil component (inductor), 2... Hardened compound, 2dc... Magnetic core (e.g., compacted magnetic core), 3... Terminal electrode, 5... Coil, 5a, 5b... Coil lead-out sections.

Claims

1. A compound comprising a metal powder and a resin composition, wherein the metal powder is a soft magnetic material, the resin composition contains a thermosetting resin, the metal powder contains a plurality of submicron particles and a plurality of large particles having a particle size larger than the particle size of the plurality of submicron particles, the content of the plurality of submicron particles in the metal powder is expressed as V1 volume%, the content of the plurality of large particles in the metal powder is expressed as V2 volume%, and V2 / V1 is 29 or more and 59 or less.

2. The compound according to claim 1, wherein the D50 of the metal powder is 5.5 μm or less.

3. The compound according to claim 1, which is a raw material for the magnetic core.

4. A molded article comprising the compound according to any one of claims 1 to 3.

5. A cured compound according to any one of claims 1 to 3.

6. A magnetic core comprising the cured product described in claim 5.

7. A coil component comprising a magnetic core and a coil as described in claim 6, wherein the magnetic core is disposed inside the coil.

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