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

Abstract

Provided is a compound powder that has high relative permeability and improves the DC superposition characteristics of a coil component having a magnetic core containing a cured product of the compound powder. The compound powder contains a metal powder and a resin composition. The metal powder is a soft magnetic material. The resin composition includes a heat-curable resin. The D50 of the metal powder is 15-21 μm. The D90 of the metal powder is 35-48 μm.

Description

Compound powder, molded body, cured compound powder, magnetic core, and coil component

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

[0002] Compound powders containing soft magnetic metal powders and electrically insulating resin compositions (such as thermosetting resins) are used as raw materials for various industrial products. (See Patent Documents 1 and 2 below.) For example, compound powders 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. Compound powders are also used as encapsulants for electronic equipment such as semiconductors or electronic circuit boards.

[0003] Japanese Patent Publication No. 2021-158316 Japanese Patent Publication No. 2023-164858

[0004] A coil component (e.g., an inductor) using a coil contains a magnetic core made of hardened compound powder. The magnetic core is placed inside the coil, and the coil is sealed within the hardened compound powder. To increase the inductance value of the coil component, a high relative permeability (unit: none) of the magnetic core is required. Furthermore, improvement of the DC superposition characteristics of the coil component is also required. However, relative permeability and DC superposition characteristics are in a trade-off relationship. DC superposition characteristics refer to the property that as the DC current 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 values ​​that occurs as the DC current flowing through the coil component increases. 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.

[0005] One aspect of this disclosure is to provide a compound powder, a molded body containing the compound powder, a cured compound powder, a cured compound powder, a cured compound powder, a cured compound powder, a cured compound powder, and a coil component containing the cured compound powder that improve the DC superposition characteristics of a coil component having a cured compound powder.

[0006] For example, one aspect of this disclosure relates to a compound powder as described in any one of the following [1] to [7], a molded article as described in [8], a cured product of the compound powder as described in [9], a magnetic core as described in

[10] , and a coil component as described in

[11] .

[0007] [1] A compound powder 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 D50 of the metal powder is 15 μm or more and 21 μm or less, and the D90 of the metal powder is 35 μm or more and 48 μm or less.

[0008] [2] The compound powder according to [1], wherein the D10 of the metal powder is 1.7 μm or more and 2.8 μm or less.

[0009] [3] The compound powder according to [1] or [2], wherein the metal powder comprises a first soft magnetic powder and a second soft magnetic powder, the composition of the first soft magnetic powder being different from the composition of the second soft magnetic powder, and the particle size of the first soft magnetic powder being larger than the particle size of the second soft magnetic powder.

[0010] [4] The compound powder according to [3], wherein the proportion of the mass of the first soft magnetic powder in the metal powder is greater than the proportion of the mass of the second soft magnetic powder in the metal powder.

[0011] [5] The compound powder according to [1] to [4], wherein the metal powder contains chromium.

[0012] [6] The compound powder according to [3], wherein the first soft magnetic powder contains chromium.

[0013] [7] A compound powder, which is a raw material for the magnetic core, as described in any one of [1] to [6].

[0014] [8] A molded article containing the compound powder described in any one of [1] to [7].

[0015] [9] A cured compound powder as described in any one of [1] to [7].

[0016] A magnetic core containing the cured material described in

[10] and [9].

[0017]

[11] A coil component comprising the magnetic core described in

[10] and a coil, wherein the magnetic core is disposed inside the coil.

[0018] According to one aspect of this disclosure, a compound powder is provided that has a high relative permeability and improves the DC superposition characteristics of a coil component having a magnetic core containing a cured compound powder, a molded body containing the compound powder, a cured compound powder, a magnetic core containing the cured compound powder, and a coil component containing the magnetic core.

[0019] 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.

[0020] 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 powder and the relative permeability of the cured product of the compound powder (e.g., the magnetic core).

[0021] (Overview of Compound Powder, Molded Body, Cured Compound Powder, Magnetic Core, and Coil Parts) The compound powder according to this embodiment comprises metal powder and a resin composition. The compound powder may be solid at room temperature (e.g., 20 ± 15°C). The metal powder and resin composition in the compound powder may be mixed. In other words, the compound powder may be rephrased as a mixture containing metal powder and 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 powder may contain either or both of the uncured resin composition and the semi-cured resin composition (semi-cured resin composition, i.e., B-stage resin composition). The compound powder may consist only of metal powder and resin composition. The compound powder may further contain other components in addition to the metal powder and resin composition.

[0022] The surface of some or all of the multiple metal particles constituting the metal powder may be covered with a resin composition. The compound powder may contain one or more metal particles that are not covered with a resin composition. The compound powder may contain one or more particles consisting solely of a resin composition. The compound powder 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.

[0023] The molded article according to this embodiment includes the compound powder described above. The molded article according to this embodiment may consist only of the compound powder. In addition to the compound powder, the molded article may also include other components such as coils. The molded article may include one or both of the uncured resin composition and the semi-cured resin composition. The cured compound powder according to this embodiment includes the cured resin composition (C-stage resin composition). In a molded article containing compound powder, or a cured compound powder, 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 powder or its cured product and suppresses a decrease in the magnetic permeability of the compound powder or its cured product.

[0024] For example, the compound powder may be a raw material for a coil component. For example, the coil component may include a hardened compound powder and a coil. For example, the compound powder may be a 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 hardened compound powder. The magnetic core may consist only of a hardened compound powder. 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 hardened compound powder 2 and a coil 5, the coil 5 may be sealed in the hardened compound powder 2, and the magnetic core 2dc containing the hardened compound powder 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 placed 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.

[0025] The median diameter (D50) of the metal powder contained in the compound powder is between 15 μm and 21 μm, and the median diameter (D90) of the metal powder contained in the compound powder is between 35 μm and 48 μm. D50 may be defined as particle size X such that the proportion of metal powder contained in the compound powder with a particle size of X or less is 50% by volume. D90 may be defined as particle size Y such that the proportion of metal powder contained in the compound powder with a particle size of Y or less is 90% by volume. When D50 and D90 are both within the above ranges, magnetic saturation of the compound powder or its cured product is suppressed, and the DC superposition characteristics of the coil component are easily improved. Furthermore, when D50 and D90 are both within the above ranges, the compound powder or its cured product is likely to have high relative permeability. In other words, when D50 and D90 are both within the above ranges, it is possible to achieve both high relative permeability and improved DC superposition characteristics. The larger D50 and D90 are, the easier it is for the relative permeability to increase, and the smaller D50 and D90 are, the easier it is for the DC superposition characteristics to improve. When D50 is less than 15 μm, the relative permeability tends to decrease. When D50 is greater than 21 μm, the DC superposition characteristics are difficult to improve. When D90 is less than 35 μm, the relative permeability tends to decrease. When D90 is greater than 48 μm, the DC superposition characteristics are difficult to improve. The relationship between the upper and lower limits of D50 and D90 and the relative permeability and DC superposition characteristics was first discovered through multiple experiments conducted by the inventors and is demonstrated by the examples and comparative examples described later.

[0026] The D10 of the metal powder may be between 1.7 μm and 2.8 μm. D10 may be defined as particle size Z at which the proportion of metal powder with a particle size of Z or less in the compound powder is 10% by volume. When D10 is between 1.7 μm and 2.8 μm, the relative permeability tends to increase, and the mechanical strength of the molded article containing the compound powder tends to increase. If D10 is too large, molding of the compound powder is not easy.

[0027] As shown in the embodiments described later, the metal powders D10, D50, and D90 can be freely controlled by mixing two or more raw material powders with different particle size distributions in a predetermined mass ratio. 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) can be freely adjusted by classifying each raw material powder using one or more sieves with predetermined mesh openings (for example, cutoff).

[0028] D10, D50, and D90 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 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.

[0029] The content of metal powder in the compound powder is not particularly limited. For example, the content of metal powder in the compound powder may be 90% by mass or more and less than 100% by mass, 93.0% by mass or more and 98.0% by mass or less, 94.0% by mass or more and 98.0% by mass or less, or 96.5% by mass or more and 97.0% by mass or less. The content of resin composition in the compound powder is also not particularly limited. For example, the content of resin composition in the compound powder may be greater than 0% by mass and 10% by mass or less, 2.0% by mass or more and 7.0% by mass or less, 2.0% by mass or more and 6.0% by mass or less, or 3.0% by mass or more and 3.5% by mass or less. The higher the content of metal powder in the compound powder, the higher the relative permeability of the cured compound powder. In other words, the lower the content of resin composition in the compound powder, the higher the relative permeability of the cured compound powder. The lower the metal powder content in the compound, the higher the mechanical strength of the cured compound. In other words, the higher the resin composition content in the compound, the higher the mechanical strength of the cured compound.

[0030] For example, the respective contents of metal powder and resin composition in the compound powder may be determined by the following method based on the specific gravity of the compound powder, metal powder, and resin composition. Specific gravity (unit: none) may be the ratio of the density of the compound powder, metal powder, and resin composition to the density of a standard substance (e.g., the density of water at 4°C). For example, the specific gravity of the compound powder, metal powder, and resin composition may be measured by a general method based on Archimedes' principle (e.g., the water displacement method). The specific gravity of the metal powder and resin composition may be measured in advance before the compound powder is manufactured. The compound powder may be separated into metal powder and resin composition (organic matter dissolved in the organic solvent) using an inert organic solvent that does not react with the metal powder and resin composition, and the specific gravity of the separated metal powder and resin composition may be measured. The specific gravity of the metal powder is S Ｍ It may be expressed as follows. The content of metal powder in the compound powder may be expressed as α mass%. The specific gravity of the resin composition is S Ｒ It may be expressed as follows. The content of the resin composition in the compound powder may be expressed as (100-α) mass%. Specific gravity S of the compound powderＣ may be represented by the following formula (1). Based on the following formula (1), the content α of the metal powder in the compound powder 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)

[0031] (Specific examples of metal powder) The metal powder (a plurality of metal particles) may include two or more types of soft magnetic powders that differ in particle size (particle size distribution). The metal powder (a plurality of metal particles) may also include two or more types of soft magnetic powders that differ in composition. For example, the metal powder may include a first soft magnetic powder (a plurality of first soft magnetic particles) and a second soft magnetic powder (a plurality of second soft magnetic particles). The composition of the first soft magnetic powder may be different from the composition of the second soft magnetic powder, and the particle size of the first soft magnetic powder may be larger than the particle size of the second soft magnetic powder. For example, the average particle size of the first soft magnetic powder may be larger than the average particle size of the second soft magnetic powder. For example, the D50 (median diameter) of the first soft magnetic powder may be larger than the D50 of the second soft magnetic powder. For example, the D90 of the first soft magnetic powder may be larger than the D90 of the second soft magnetic powder. For example, the D10 of the first soft magnetic powder may be larger than the D10 of the second soft magnetic powder. If the compound powder contains only the first soft magnetic powder with a large particle size as the metal powder, gaps are likely to be formed between adjacent first soft magnetic particles, and it is difficult to increase the filling rate of the metal powder in the compound powder. On the other hand, when the compound powder contains the first soft magnetic powder and the second soft magnetic powder as the metal powder, the second soft magnetic particles smaller than the first soft magnetic particles are filled in the gaps between the plurality of first soft magnetic particles, and the filling rate of the metal powder in the compound powder increases. In other words, because the compound powder contains the first soft magnetic powder and the second soft magnetic powder that differ in particle size, the specific gravity of the compound powder increases. As a result, the relative permeability improves. Furthermore, as the filling rate of the metal powder in the compound powder increases, the cured product of the compound powder becomes denser, and the mechanical strength of the cured product improves.

[0032] The proportion of the mass of the first soft magnetic powder in the metal powder is greater than the proportion of the mass of the second soft magnetic powder in the metal powder. For example, the mass of the first soft magnetic powder may be expressed as M1, and the mass of the second soft magnetic powder may be expressed as M2. For example, M1 / (M1+M2) may be between 0.70 and 0.95, or between 0.75 and 0.86, and M2 / (M1+M2) may be between 0.05 and 0.30, or between 0.14 and 0.25. When M1 / (M1+M2) and M2 / (M1+M2) are within the above ranges, the second soft magnetic particles, which are smaller than the first soft magnetic particles, are more easily filled in the gaps between multiple first soft magnetic particles, and the packing density of the metal powder in the compound powder (specific gravity of the compound powder) tends to increase. As a result, the relative permeability and mechanical strength tend to increase.

[0033] The compound powder may further contain a non-metallic filler in addition to the metal powder. For example, the compound powder may contain silica (SiO₂) as the non-metallic filler. ２ It may contain a filler (particulate filler) made of the following: The particle size (or particle size distribution) of the nonmetallic filler may be approximately or completely equal to the particle size (or particle size distribution) of the metal powder.

[0034] 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 element 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, when the metal powder (e.g., the first soft magnetic powder) contains Cr, oxidation of the metal powder is easily suppressed, the metal powder is less prone to rusting, and the decrease in relative permeability is easily suppressed.

[0035] 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) ５ This is a perfectly spherical pure iron powder obtained by the reduction (thermal decomposition) of (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.

[0036] Part or all of the plurality of metal particles constituting the metal powder may be covered with an insulating film. Part or the whole of the surface of each metal particle may be covered with an insulating film. By covering the metal powder with an insulating film, the electrical insulation of the compound powder is improved. When the insulating film contains glass, the surface of the insulating film tends to be smooth, and the friction between the plurality of metal particles is easily suppressed. As a result, aggregation (blocking) of the compound powder is easily suppressed, and the fluidity of the compound powder is easily improved. Part or the whole of the surface of the insulating film may be covered with a resin composition.

[0037] For example, the insulating film may contain at least one component selected from the group consisting of glass, phosphoric acid (phosphate), silica (SiO ２ ), iron oxide (Fe ２ O ３ ), and chromium oxide (Cr ２ O ３ ). 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 of silicate glass (silicate), phosphosilicate glass (phosphosilicate), and borosilicate glass (borosilicate). The composition of the insulating film may be measured by at least one of X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray analysis (EDX). The insulating film may be formed by a wet method using a solution of alkoxysilane or the like, or a dry method such as mechanofusion. For example, the thickness of the insulating film may be 10 nm or more and 200 nm or less. The thickness of the insulating film may be measured at the cross-section of the metal particles by a transmission electron microscope (TEM) and EDX.

[0038] (Specific Examples of Resin Compositions) The resin composition may consist of the remaining portion (non-volatile component) of the compound powder excluding the metal powder. 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.

[0039] The thermosetting resin contained in the resin composition may be at least one resin selected from the group consisting of epoxy resins, phenolic resins, bismaleimide resins, polyimide resins, and polyamideimide resins. In addition to the thermosetting resin, the resin composition may further contain other resins (e.g., thermoplastic resins). For example, the resin composition may further contain at least one other resin selected from the group consisting of polyphenylene sulfide resins, acrylic resins, methacrylic resins, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate, and silicone resins.

[0040] <Epoxy Resin and Curing Agent> The epoxy resin may be at least one resin selected from the group consisting of biphenyl type epoxy resin, stilbene type epoxy resin, diphenylmethane type epoxy resin, sulfur atom-containing type epoxy resin, novolak type epoxy resin, dicyclopentadiene type epoxy resin, salicylaldehyde type epoxy resin, copolymerization type epoxy resin of naphthols and phenols, epoxy compound of aralkyl type phenol resin, bisphenol type epoxy resin, glycidyl ether type epoxy resin of alcohols, glycidyl ether type epoxy resin of para-xylylene-modified phenol resin and / or meta-xylylene-modified phenol resin, glycidyl ether type epoxy resin of terpene-modified phenol resin, cyclopentadiene type epoxy resin, glycidyl ether type epoxy resin of polycyclic aromatic ring-modified phenol resin, glycidyl ether type epoxy resin of naphthalene ring-containing phenol resin, glycidyl ester type epoxy resin, glycidyl type or methyl glycidyl type epoxy resin, alicyclic type epoxy resin, halogenated phenol novolak type epoxy resin, orthocresol novolak type epoxy resin, hydroquinone type epoxy resin, trimethylolpropane type epoxy resin, and linear aliphatic epoxy resin obtained by oxidizing an olefin bond with a peracid such as peracetic acid.

[0041] At least part of the epoxy resin may be a naphthalene type epoxy resin having a naphthalene structure. The naphthalene type epoxy resin is solid at room temperature. When the compound powder contains the naphthalene type epoxy resin, the product (cured product of the compound powder) produced from the compound powder is likely to have high mechanical strength at room temperature and high temperature. The naphthalene type epoxy resin may be at least one resin selected from the group consisting of naphthalene diepoxy compound, naphthylene ether type epoxy resin, naphthalene novolak type epoxy resin, methylene bond dimer of naphthalene diepoxy compound, and methylene conjugate of naphthalene monoepoxy compound and naphthalene diepoxy compound. The epoxy resin may contain a bifunctional epoxy resin. For example, the bifunctional epoxy resin may be at least one resin of α-naphthol type epoxy resin and β-naphthol type epoxy resin.

[0042] 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 powder, forming a strong crosslinked network. As a result, the movement of the epoxy resin in the cured compound powder 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 powder tends to have high mechanical strength at high temperatures.

[0043] The compound powder may contain one of the epoxy resins listed above. The compound powder may contain multiple types of epoxy resins listed above.

[0044] Curing agents are classified into two types: those that cure epoxy resins in a low temperature to room temperature range, and heat-curing curing agents that cure epoxy resins upon heating. For example, curing agents that cure epoxy resins in a low temperature to room temperature range include aliphatic polyamines, polyaminoamides, and polymercaptans. For example, heat-curing curing agents include aromatic polyamines, acid anhydrides, phenolic resins, phenol novolac resins, and dicyandiamide (DICY). From the viewpoint of improving the heat resistance (mechanical strength at high temperatures) of the cured compound powder, the curing agent may preferably be a heat-curing curing agent, more preferably a phenolic resin, and even more preferably a phenol novolac resin.

[0045] Part or all of the curing agent may be a phenolic resin. For example, the phenolic resin may be at least one resin selected from the group consisting of aralkyl phenolic resins, dicyclopentadiene phenolic resins, salicylaldehyde phenolic resins, novolac phenolic resins, copolymer phenolic resins of benzaldehyde phenol and aralkyl phenol, paraxylylene and / or metaxylylene modified phenolic resins, melamine modified phenolic resins, terpene modified phenolic resins, dicyclopentadiene naphthol resins, cyclopentadiene modified phenolic resins, polycyclic aromatic ring modified phenolic resins, biphenyl phenolic resins, and triphenylmethane phenolic resins. The phenolic resin may also be a copolymer composed of two or more of the above phenolic resins.

[0046] 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.

[0047] 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.

[0048] The compound powder may contain one of the above-mentioned phenolic resins as a curing agent. The compound powder may contain multiple of the above-mentioned phenolic resins as a curing agent.

[0049] 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.

[0050] <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 powder may contain one type of curing accelerator. The compound powder may contain multiple types of curing accelerators.

[0051] 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).

[0052] <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 powder. 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 powder may contain one of the above coupling agents. The compound powder may contain multiple types of the above coupling agents.

[0053] <Wax> The compound powder may contain wax. Wax may be rephrased as a lubricant or release agent. The inclusion of wax in the compound powder 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 powder (cured compound powder) 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 powder may contain one of the above types of wax. The compound powder may contain multiple types of the above types of wax.

[0054] <Flame Retardant> The compound powder may contain a flame retardant. 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 powder may contain one of the above flame retardants, or more of the above flame retardants.

[0055] (Method for producing compound powder) The method for producing compound powder includes the step of preparing a mixed powder containing metal powder and a resin composition.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] The mixing time depends on the type of mixing means, the volume of the mixing means, and the amount of compound powder produced. The mixing time is not limited. For example, the mixing time may be between 1 minute and 20 minutes. For example, the temperature (heating temperature) of the metal powder and resin composition during mixing 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.

[0060] 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).

[0061] The mixed powder described above may be used as a compound powder itself. A compound powder with an adjusted particle size distribution may be obtained by grinding the mixed powder. A compound powder with an adjusted particle size distribution may also be obtained by classifying the mixed powder using a sieve.

[0062] (Methods for manufacturing molded articles, cured products, magnetic cores, and coil components) A molded article is obtained by molding the compound powder 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 powder (e.g., a magnetic core) is obtained. For example, the method for molding the compound powder 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 powder in a heating chamber to make it fluid, and supplying (pressure-injecting) the fluidized compound powder from the heating chamber into the mold through a casting runner. Depending on the industrial product (e.g., coil component) to be manufactured using the compound powder, the dimensions and shape of the mold used for molding the compound powder may be selected. The heat treatment temperature of the molded body may be any temperature at which the resin composition in the molded body is sufficiently cured, 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 body, the heat treatment of the molded body may be carried out under an inert atmosphere. A paste which is a mixture of compound powder and an organic solvent may be used to manufacture a molded body containing compound powder, a cured product of compound powder, a magnetic core containing the cured product of compound powder, and a coil component containing the magnetic core.

[0063] (Analysis Method) The composition of the compound powder 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 powder 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.

[0064] 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.

[0065] For example, industrial products manufactured using compound powder are not limited to inductors. Specific industrial products manufactured using compound powder may include reactors, transformers, motor stators, motor yokes, power modules, thyristor valves, noise filters (EMI filters), choke coils, and solenoid cores.

[0066] The compound powder, molded articles containing the compound powder, or cured products of the compound powder may be encapsulants (for example, encapsulants for electronic components). The compound powder 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 powder, molded articles containing the compound powder, or cured products of the compound powder may be encapsulants (underfills, etc.) for semiconductor packages such as IC packages and LSI packages.

[0067] 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.

[0068] [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.

[0069] 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.

[0070] The "curing agent 1" described below was HE910 manufactured by Air Water Performance Chemical Co., Ltd., and was a triphenylmethane-type phenolic resin.

[0071] The "curing agent 2" described below was MEHC7851 manufactured by UBE Corporation (formerly Meiwa Chemicals Co., Ltd.), and was a biphenyl aralkyl type phenolic resin.

[0072] The "curing agent 3" described below was MEW-1800 manufactured by UBE Corporation (formerly Meiwa Chemicals Co., Ltd.), and was a phenol novolac resin.

[0073] The "curing accelerator" described below was U-CAT3512T manufactured by Sunapro Co., Ltd., and was an aromatic dimethylurea.

[0074] The "coupling agent" described below was KBM-5803, manufactured by Shin-Etsu Chemical Co., Ltd., and was 8-methacryloxyoctyltrimethoxysilane.

[0075] [Components contained in the metal powder] The "Powder 1" described below is KUAMET 6B2-II manufactured by Epson Atomics Corporation, and is a metal (soft magnetic material) composed of Fe, Cr, Si, and B. Powder 1 was amorphous. The cutoff diameter of Powder 1 was 75 μm. In other words, particles with a particle size (maximum particle width) larger than 75 μm were removed from Powder 1 by sieving. The average particle size of Powder 1 was 30 μm.

[0076] The "Powder 2" described below was KUAMET 6B2-II manufactured by Epson Atomics Corporation, and was a metal (soft magnetic material) composed of Fe, Cr, Si, and B. Powder 2 was amorphous. The cutoff diameter of Powder 2 was 53 μm. In other words, particles with a particle size (maximum particle width) larger than 53 μm were removed from Powder 2 by sieving. The average particle size of Powder 2 was 27 μm.

[0077] The "powder 3" described below was KUAMET 6B2-II manufactured by Epson Atomics Corporation, and was a metal (soft magnetic material) composed of Fe, Cr, Si, and B. Powder 3 was amorphous. The cutoff diameter of powder 3 was 32 μm. In other words, particles with a particle size (maximum particle width) larger than 32 μm were removed from powder 3 by sieving. The average particle size of powder 3 was 21 μm.

[0078] The "powder 4" described below was AW2-08 manufactured by Epson Atomics Corporation, and was a metal (soft magnetic material) composed of Fe, Cr, Si, and B. Powder 4 was amorphous. The average particle size of powder 4 was 11 μm.

[0079] The "powder 5" described below was NC1 manufactured by Epson Atomics Corporation and was a metal (soft magnetic material) composed of Fe, Si, Nb, and B. Powder 5 contained metal nanocrystals. The cutoff diameter of powder 5 was 53 μm. In other words, particles with a particle size (maximum particle width) larger than 53 μm were removed from powder 5 by sieving. The average particle size of powder 5 was 31 μm.

[0080] The "powder 6" described below was SAP-2DC manufactured by Shinto Kogyo Co., Ltd., and was a metal (soft magnetic material) composed of Fe, Si, and P. Powder 6 was amorphous. The average particle size of powder 6 was within the range of 1.9 to 2.5 μm.

[0081] The "Powder 7" described below was manufactured by Shinto Kogyo Co., Ltd. and was a metal (soft magnetic material) composed of Fe, Cr, and Si. The average particle size of Powder 7 was within the range of 1.9 to 2.3 μm.

[0082] The "Powder 8" 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 8 was within the range of 1.8 to 2.2 μm.

[0083] Each of powders 1 to 5 may be the first soft magnetic powder described in the embodiment. Each of powders 6 to 8 may be the second soft magnetic powder described in the embodiment.

[0084] (Example 1) The resin composition of Example 1 was a mixture consisting of resin 1, resin 2, curing agent 1, curing agent 2, curing agent 3, curing accelerator, and coupling agent. The mass ratio (in parts by mass) of each of resin 1, resin 2, curing agent 1, curing agent 2, curing agent 3, curing accelerator, and coupling agent in the resin composition was adjusted to the values ​​shown in Table 1 below.

[0085] The metal powder of Example 1 was prepared by mixing powder 3 and powder 7. Based on the particle size distribution of powder 3 and powder 7, and the mixing ratio of powder 3 and powder 7, the D10, D50, and D90 of the metal powder were adjusted to desired values. The content (in mass%) of powder 3 and powder 7 in the metal powder was adjusted to the values ​​shown in Table 3 below. The D10 (in μm), D50 (in μm), and D90 (in μm) of the metal powder are shown in Table 5 below. D10, D50, and D90 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.

[0086] 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 powder was adjusted to the value shown in Table 5 below. In other words, the content of resin composition in the compound powder was adjusted to (100 - α) mass%.

[0087] <Measurement of Relative Permeability> A toroidal core (compressed magnetic core) made of hardened compound powder was obtained by transfer molding of the compound powder at 175°C and post-curing (heating at 175°C for 5.5 hours) following the transfer molding. The pressure applied to the compound powder 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.

[0088] 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 5 below. A relative permeability of 38 or higher is desirable.

[0089] <Measurement of DC Superimposed Rated Current> The primary winding was wound around a toroidal core with 33 turns, and the secondary winding was wound around a toroidal core with 10 turns. The DC superimposed rated current Isat of the sample prepared by the above method was measured. Isat is the DC current at the point when the relative permeability of the sample decreases by 30% from its initial value, during the process in which the DC current flowing through the windings constituting the sample increases from zero A. A measuring device (product name: SY-960) manufactured by Iwasaki Communication Equipment Co., Ltd. was used to measure Isat. Isat (unit: A) is shown in Table 5 below. It is desirable that Isat be 9000 A or higher.

[0090] (Examples 2-9 and Comparative Examples 1-6) The mass ratios (in parts by mass) of resin 1, resin 2, curing agent 1, curing agent 2, curing agent 3, curing accelerator, and coupling agent in each of the resin compositions of Examples 2-9 were adjusted to the values ​​shown in Table 1 below. The mass ratios (in parts by mass) of resin 1, resin 2, curing agent 1, curing agent 2, curing agent 3, curing accelerator, and coupling agent in each of the resin compositions of Comparative Examples 1-6 were adjusted to the values ​​shown in Table 2 below.

[0091] The metal powders in Examples 2-9 and Comparative Examples 1-6 were prepared by mixing two or more powders selected from the group consisting of powders 1-8. The content (in mass %) of powders 1-8 in each of the metal powders in Examples 2-9 was adjusted to the values ​​shown in Table 3 below. The content (in mass %) of powders 1-8 in each of the metal powders in Comparative Examples 1-6 was adjusted to the values ​​shown in Table 4 below. The D10, D50, and D90 values ​​of the metal powders in Examples 2-9 are shown in Table 5 below. The D10, D50, and D90 values ​​of the metal powders in Comparative Examples 1-6 are shown in Table 6 below. The content α of the metal powder in the compound powders in Examples 2-9 was adjusted to the values ​​shown in Table 5 below. The content α of the metal powder in the compound powders in Comparative Examples 1-6 was adjusted to the values ​​shown in Table 6 below.

[0092] Except for the matters described above, the compound powders for Examples 2-9 and Comparative Examples 1-6 were prepared in the same manner as in Example 1. The relative permeability and Isat of Examples 2-9 and Comparative Examples 1-6 were measured in the same manner as in Example 1. The relative permeability and Isat of Examples 2-9 are shown in Table 5 below. The relative permeability and Isat of Comparative Examples 1-6 are shown in Table 6 below.

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099] For example, the compound powder relating to one aspect of this disclosure may be used as a raw material for the magnetic core contained in an inductor.

[0100] 1... Coil component (inductor), 2... Hardened compound powder, 2dc... Magnetic core (e.g., compacted magnetic core), 3... Terminal electrode, 5... Coil, 5a, 5b... Coil lead-out sections.

Claims

1. A compound powder 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 D50 of the metal powder is 15 μm or more and 21 μm or less, and the D90 of the metal powder is 35 μm or more and 48 μm or less.

2. The compound powder according to claim 1, wherein the D10 of the metal powder is 1.7 μm or more and 2.8 μm or less.

3. The compound powder according to claim 1, wherein the metal powder comprises a first soft magnetic powder and a second soft magnetic powder, the composition of the first soft magnetic powder being different from the composition of the second soft magnetic powder, and the particle size of the first soft magnetic powder being larger than the particle size of the second soft magnetic powder.

4. The compound powder according to claim 3, wherein the proportion of the mass of the first soft magnetic powder in the metal powder is greater than the proportion of the mass of the second soft magnetic powder in the metal powder.

5. The compound powder according to claim 1, wherein the metal powder contains chromium.

6. The compound powder according to claim 3, wherein the first soft magnetic powder contains chromium.

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

8. A molded article comprising the compound powder described in any one of claims 1 to 7.

9. A cured compound powder according to any one of claims 1 to 7.

10. A magnetic core comprising the cured product described in claim 9.

11. A coil component comprising a magnetic core and a coil as described in claim 10, wherein the magnetic core is disposed inside the coil.

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