Organic film-coated soft magnetic powder, method for producing the same, powder magnetic core, magnetic element, and electronic device

Abstract

Provided are an organic film-coated soft magnetic powder capable of producing a press powder body having excellent filling properties and compatibility with a binder resin, less strength deviation, a method for producing the same, a press magnetic core and a magnetic element each containing the organic film-coated soft magnetic powder, and an electronic device provided with the magnetic element. An organic film-coated soft magnetic powder has: an oxide film-coated soft magnetic powder having a soft magnetic powder and an oxide film containing elements contained in a soft magnetic metal material; and an organic film containing a compound derived from a coupling agent having an amino group, a hydrolyzable group, and a linear alkyl group, with an average particle diameter of 1.0 μm or more and less than 10.0 μm on a volume basis, and a minimum coating area [m 2 / g] of the coupling agent is set as CS, a specific surface area [m 2 / g] of the oxide film-coated soft magnetic powder is set as Sm, and an actual addition amount [mass %] of the coupling agent is 0.5 times or more and less than 2.0 times a theoretical addition amount CA [mass %] of the coupling agent calculated from the following formula. CA = Sm / CS x 100

Description

Technical Field

[0001] This invention relates to organic film-coated soft magnetic powder, a method for manufacturing organic film-coated soft magnetic powder, pressed magnetic cores, magnetic components, and electronic devices. Background Technology

[0002] Patent Document 1 discloses an insulating coating of soft magnetic powder, comprising: soft magnetic powder; an inorganic insulating film covering the particle surface of the soft magnetic powder, comprising ceramic; and an organic film covering the surface of the inorganic insulating film, comprising a compound derived from a coupling agent having hydrophobic functional groups.

[0003] In addition, Patent Document 1 discloses a soft magnetic powder with an average particle size of 1 μm or more and 20 μm or less, and the use of a silane coupling agent having an NH2 group, an isolation component and a hydrolyzable group.

[0004] Based on this structure, it is possible to achieve an insulating soft magnetic powder with excellent moisture resistance, accompanied by a reduction in moisture absorption and fluidity.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2024-140109 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] Patent Document 1 discloses a method for forming an organic film using a silane coupling agent containing an NH2 group in its description of insulating coated soft magnetic powder. However, in the insulating coated soft magnetic powder formed using this silane coupling agent, there is a technical problem that it is difficult to simultaneously achieve both filler properties and compatibility with the adhesive resin. Furthermore, pressed powder bodies manufactured using such insulating coated soft magnetic powder may exhibit significant strength deviations.

[0010] Technical solutions for solving technical problems

[0011] The organic film-coated soft magnetic powder involved in the application examples of the present invention has the following characteristics: An oxide film coating soft magnetic powder comprises a soft magnetic powder made of a soft magnetic metallic material containing Fe, Si, and B, and an oxide film disposed on the surface of the soft magnetic powder and containing oxides of the elements contained in the soft magnetic metallic material; and An organic film, disposed on the surface of the oxide film-coated soft magnetic powder, comprises a compound derived from a coupling agent having an amino group, a hydrolyzable group, and a straight-chain alkyl group located between the amino group and the hydrolyzable group. The average particle size, measured by a laser diffraction particle size distribution measuring device, is greater than 1.0 μm and less than 10.0 μm based on volume. The minimum coating area of ​​the coupling agent [m 2 Set / g] to CS, The specific surface area [m²] of the soft magnetic powder coated with the oxide film 2 When / g] is set to Sm The actual amount of coupling agent added [mass%], calculated from the content [mass%] of the compound, is more than 0.5 times and less than 2.0 times the theoretical amount of coupling agent added CA [mass%] calculated by the following formula.

[0012] CA = Sm / CS × 100

[0013] The application examples of this invention relate to a method for manufacturing organic film-coated soft magnetic powder. The process includes the following steps: A soft magnetic powder is coated with an oxide film, comprising an oxide film of an oxide film containing oxides of elements contained in the soft magnetic metal material, and having an amino group, a hydrolyzable group, and a straight-chain alkyl group located between the amino group and the hydrolyzable group. The coupling agent undergoes a hydrolysis and condensation reaction to form an organic film containing compounds derived from the coupling agent, disposed on the surface of the oxide film-coated soft magnetic powder, thus obtaining an organic film-coated soft magnetic powder. The average particle size, measured by a laser diffraction particle size distribution measuring device, is greater than 1.0 μm and less than 10.0 μm based on volume. The minimum coating area of ​​the coupling agent [m 2 Set / g] to CS, The specific surface area [m²] of the soft magnetic powder coated with the oxide film 2 When / g] is set to Sm The actual amount of coupling agent added in the process [mass%] is more than 0.5 times and less than 2.0 times the theoretical amount of coupling agent CA [mass%] calculated by the following formula.

[0014] CA = Sm / CS × 100

[0015] The powder-pressed magnetic core involved in the application examples of this invention, This includes the organic film-coated soft magnetic powder involved in the application examples of the present invention.

[0016] The magnetic element involved in the application examples of the present invention, The powder core is provided in the application example of the present invention.

[0017] The electronic devices involved in the application examples of this invention, The magnetic element described in the application example of the present invention is provided. Attached Figure Description

[0018] Figure 1 This is a schematic cross-sectional view of a particle of organic film-coated soft magnetic powder involved in the embodiment.

[0019] Figure 2 This is a cross-sectional view of a particle schematically representing a modified example of an organic film-coated soft magnetic powder according to the embodiment.

[0020] Figure 3 This is a schematic top view representing a loop-shaped coil component.

[0021] Figure 4 It is a perspective perspective view schematically representing a coil component with a closed magnetic circuit.

[0022] Figure 5 This is a perspective view of a mobile personal computer, which is an electronic device involved in the implementation method.

[0023] Figure 6 This is a top view of a smartphone, which is an electronic device involved in the implementation.

[0024] Figure 7 This is a perspective view of a digital camera, which is an electronic device involved in the implementation method.

[0025] Figure 8 Table 1 shows the composition of the organic film-coated soft magnetic powder of samples No.1 to 13.

[0026] Figure 9 Table 2 shows the composition of the organic film-coated soft magnetic powder of samples No. 14 to 21.

[0027] Figure 10 Table 3 shows the evaluation results of the organic film-coated soft magnetic powders of samples No.1 to No.13.

[0028] Figure 11 Table 4 shows the evaluation results of the organic film-coated soft magnetic powders of samples No. 14 to 21.

[0029] Symbol Explanation

[0030] 1: Organic film coated with soft magnetic powder; 2: Oxide film coated with soft magnetic powder; 3: Organic film; 4: Insulating film; 10: Coil component; 11: Pressed powder magnetic core; 12: Wire; 20: Coil component; 21: Pressed powder magnetic core; 22: Wire; 24: Soft magnetic powder; 26: Oxide film; 100: Display unit; 1000: Magnetic component; 1100: Personal computer; 1102: Keyboard; 1104: Main body; 1106: Display unit; 1200: Smartphone; 1202: Operation button; 1204: Earpiece; 1206: Microphone; 1300: Digital camera; 1302: Housing; 1304: Light receiving unit; 1306: Shutter button; 1308: Memory. Detailed Implementation

[0031] Hereinafter, based on the preferred embodiments shown in the accompanying drawings, the organic film-coated soft magnetic powder, the manufacturing method of the organic film-coated soft magnetic powder, the pressed magnetic core, the magnetic element, and the electronic device involved in the present invention will be described in detail.

[0032] 1. Organic film-coated soft magnetic powder

[0033] First, the organic film-coated soft magnetic powder 1 involved in the embodiment will be described.

[0034] Figure 1 This is a schematic cross-sectional view of a particle of the organic film-coated soft magnetic powder 1 involved in the embodiment.

[0035] Figure 1 The organic film-coated soft magnetic powder 1 shown has an oxide film-coated soft magnetic powder 2 and an organic film 3 disposed such that it coats the surface of the oxide film-coated soft magnetic powder 2. It should be noted that, in this specification, "coating" refers to the concept of covering not only the entire surface of the oxide film-coated soft magnetic powder 2, but also a portion of the surface.

[0036] The oxide film-coated soft magnetic powder 2 comprises a soft magnetic powder 24 made of a soft magnetic metal material containing Fe, Si, and B, and an oxide film 26 disposed on the surface of the soft magnetic powder 24. The oxide film 26 comprises oxides of the elements contained in the aforementioned soft magnetic metal material.

[0037] Organic membrane 3 comprises compounds derived from coupling agents having an amino group, a hydrolyzable group, and a straight-chain alkyl group located between the amino and hydrolyzable groups.

[0038] In addition, the average particle size of the organic film-coated soft magnetic powder 1, measured by a laser diffraction particle size distribution measuring device, is 1.0 μm or more and less than 10.0 μm on a volume basis.

[0039] Furthermore, the minimum coating area of ​​the coupling agent [m] 2 / g] is set as CS, and the specific surface area of ​​the soft magnetic powder 2 coated with oxide film is [m 2 When / g] is set as Sm, the actual amount of coupling agent added [mass%] calculated from the content [mass%] of the aforementioned compound is more than 0.5 times and less than 2.0 times the theoretical amount of coupling agent added CA [mass%] calculated by the following formula.

[0040] CA = Sm / CS × 100

[0041] Based on this structure, an organic film-coated soft magnetic powder 1 can be obtained, which exhibits excellent filling properties and compatibility with binder resins, and has minimal strength deviation in pressed powder. Therefore, by using the organic film-coated soft magnetic powder 1, a pressed powder with high density and stable mechanical strength can be obtained.

[0042] 1.1. Oxide film coating soft magnetic powder

[0043] Figure 1 The oxide film coating soft magnetic powder 2 shown has soft magnetic powder 24 and oxide film 26.

[0044] 1.1.1. Composition of soft magnetic metallic materials

[0045] The soft magnetic powder 24 is composed of a soft magnetic metallic material containing Fe, Si and B.

[0046] Examples of metallic structures composed of soft magnetic metallic materials include crystalline structures, amorphous structures, and microcrystalline (nanocrystalline) structures. Among these, soft magnetic metallic materials preferably include amorphous alloys composed of amorphous structures or nanocrystalline alloys composed of nanocrystalline structures. By including these components, the coercivity is reduced, which helps to reduce the hysteresis loss of magnetic components. It should be noted that structures with different crystallinities can also coexist in soft magnetic metallic materials.

[0047] As amorphous alloy materials and nanocrystalline alloy materials, examples include Fe-Si-B series alloy materials, Fe-Si-BC series alloy materials, Fe-Si-B-Cr-C series alloy materials, Fe-Co-Si-B series alloy materials, Fe-Si-B-Nb series alloy materials, and Fe-Si-B-Nb-Cu series alloy materials.

[0048] The soft magnetic metallic material is particularly preferably an amorphous alloy material composed of the following composition and impurities. This allows for the production of oxide-coated soft magnetic powder 2, which combines high permeability and low coercivity.

[0049] Composition formula expressed by atomic ratio (Fe) 1-xCr x ) a (Si 1-y B y ) b C c

[0050] [b is 100-ac.]

[0051] in addition, 70.0≤a≤82.0, 0≤c≤4.0, 0≤x≤0.060, 0.30≤y≤0.90. The above composition formula shows the atomic ratio of the five elements Fe, Cr, Si, B, and C. It should be noted that in the above composition formula, the elements Fe, Si, and B must be included.

[0052] Fe (iron) has a significant impact on the basic magnetic and mechanical properties of the oxide film-coated soft magnetic powder 2.

[0053] The Fe content is not particularly limited, but it is set to be Fe as the main component in the oxide film-coated soft magnetic powder 2, that is, the atomic ratio is the highest. In the oxide film-coated soft magnetic powder 2, the Fe content is preferably 72.0 atomic% or more and 82.0 atomic% or less, more preferably 72.5 atomic% or more and 81.5 atomic% or less, and even more preferably 73.0 atomic% or more and 81.0 atomic% or less.

[0054] Cr (chromium) enhances the corrosion resistance of the oxide film-coated soft magnetic powder 2. This improved corrosion resistance suppresses oxidation, thus mitigating the decrease in magnetic properties associated with oxidation. Furthermore, the passive film also helps improve insulation, suppressing eddy current losses in the oxide film-coated soft magnetic powder 2.

[0055] x represents the ratio of the Cr content to the total content when the sum of the Fe and Cr contents is set to 1. In the oxide film-coated soft magnetic powder 2, it is preferably 0 ≤ x ≤ 0.060, more preferably 0.010 ≤ x ≤ 0.050, and even more preferably 0.020 ≤ x ≤ 0.040.

[0056] 'a' represents the ratio of the total Fe content to the total Cr content when the total mass of the five elements is set to 100. In the oxide film-coated soft magnetic powder 2, 'a' is preferably 70.0 ≤ a ≤ 82.0, more preferably 72.0 ≤ a ≤ 81.0, and even more preferably 73.0 ≤ a ≤ 80.5.

[0057] When silicon (Si) is used to manufacture an oxide film-coated soft magnetic powder 2 from raw materials, it promotes amorphization and increases the magnetic permeability of the oxide film-coated soft magnetic powder 2. This enables the achievement of high magnetic permeability and low coercivity.

[0058] Boron (B) promotes amorphization when an oxide film is coated onto soft magnetic powder 2 made from raw materials. In particular, by using Si and B together, amorphization can be synergistically promoted based on the difference in their atomic radii. As a result, both high permeability and low coercivity can be achieved.

[0059] y represents the ratio of the content of B to the total content when the sum of the contents of Si and B is set to 1. In the oxide film-coated soft magnetic powder 2, it is preferably 0.30≤y≤0.90, and more preferably 0.40≤y≤0.80.

[0060] When carbon (C) is used to melt the raw material of the oxide-coated soft magnetic powder 2, it reduces the viscosity of the melt, making amorphization and micronization easier. This allows for the production of oxide-coated soft magnetic powder 2 with a small diameter and high magnetic permeability. As a result, eddy current losses can be suppressed even in the high-frequency region.

[0061] c represents the content of C when the total mass of the five elements is 100. In the oxide film-coated soft magnetic powder 2, it is preferably 0 ≤ c ≤ 4.0, more preferably 1.0 ≤ c ≤ 2.8, and even more preferably 1.5 ≤ c ≤ 2.5.

[0062] The composition of soft magnetic metallic materials is determined by the following analytical methods.

[0063] Examples of analytical methods include the atomic absorption spectrophotometry of iron and steel specified in JIS G 1257:2000, the inductively coupled plasma atomic emission spectrometry of iron and steel specified in JIS G 1258:2007, the spark discharge atomic emission spectrometry of iron and steel specified in JIS G 1253:2002, the fluorescence X-ray analysis of iron and steel specified in JIS G 1256:1997, and the gravimetric / titration / absorbance spectrophotometry specified in JIS G 1211~G1237.

[0064] Specifically, examples include solid-state emission spectrometry analysis devices manufactured by SPECTRO Corporation, particularly spark discharge emission spectrometry analysis devices, model: SPECTROLAB, type: LAMVB08A; and Rigaku Corporation's inductively coupled plasma instrument CIROS120 model.

[0065] In addition, especially when determining C (carbon) and S (sulfur), the oxygen flow combustion (high-frequency induction furnace combustion)-infrared absorption method specified in JIS G 1211:2011 can also be used. Specifically, the carbon / sulfur analysis device CS-200 manufactured by LECO can be cited as an example.

[0066] In addition, especially when determining N (nitrogen) and O (oxygen), the quantitative method for nitrogen in iron and steel specified in JIS G 1228:1997 and the general rules for quantitative method for oxygen in metallic materials specified in JIS Z 2613:2006 can be used. Specifically, the oxygen / nitrogen analyzer manufactured by LECO, TC-300 / EF-300, can be cited as examples.

[0067] 1.1.2. Oxide film

[0068] The oxide film 26 contains oxides of the elements contained in the aforementioned soft magnetic metal material. Since the soft magnetic metal material contains Fe, Si, and B, the oxide film 26 contains at least one of iron oxide, silicon oxide, and boron oxide.

[0069] In addition to the oxides mentioned above, the oxide film 26 may also contain chromium oxide, nickel oxide, cobalt oxide, manganese oxide, phosphorus oxide, aluminum oxide, magnesium oxide, calcium oxide, zinc oxide, titanium oxide, vanadium oxide, cerium oxide, etc. Furthermore, the oxide film 26 may contain two or more of these oxides.

[0070] These oxides inhibit the oxidation of the soft magnetic powder 24, helping to suppress the decrease in magnetic properties. Furthermore, these oxides have a high density of hydroxyl groups on their surface. Therefore, they contribute to improving the compactness of the organic film 3, which will be described later.

[0071] The average thickness of the oxide film 26 is preferably 0.5 nm or more and 50 nm or less, more preferably 1 nm or more and 10 nm or less. This further improves the corrosion resistance of the oxide film coating the soft magnetic powder 2 and the compactness of the organic film 3.

[0072] It should be noted that the average thickness of the oxide film 26 is determined, for example, by magnifying and observing a cross-section of the organic film-coated soft magnetic powder 1. Specifically, a particle of the organic film-coated soft magnetic powder 1 is cut to prepare a cross-sectional thin-film sample. Then, the obtained cross-sectional thin-film sample is observed using a scanning transmission electron microscope, and the thickness of the oxide film 26 is measured at at least five locations. The measured values ​​are then averaged, and the calculated result is taken as the average thickness of the oxide film 26. The distribution range of the oxide film 26 in the image can be more clearly confirmed, for example, by combining EDX (energy-dispersive X-ray diffraction) analysis and Auger electron spectroscopy.

[0073] The oxide film-coated soft magnetic powder 2 can be a powder manufactured by any method. Examples of manufacturing methods include various atomization methods such as water atomization, gas atomization, and rotating water atomization, as well as reduction, carbonylation, and pulverization methods. Among these, atomization is preferred. Furthermore, in water atomization and rotating water atomization, since pulverization occurs through contact between molten metal and water, an oxide film 26 of appropriate thickness can easily be formed on the surface of the oxide film-coated soft magnetic powder 2. Moreover, in rotating water atomization, oxide film-coated soft magnetic powder 2 with the particle size described later can be effectively manufactured.

[0074] The thickness of the oxide film 26 is adjusted according to the manufacturing conditions of the oxide film coating soft magnetic powder 2, such as the cooling rate of the molten metal. Specifically, when the cooling rate is slowed down, the oxide film 26 tends to become thicker.

[0075] In addition, the oxide film 26 preferably covers the entire surface of the soft magnetic powder 24, but it may also have intermittent parts.

[0076] 1.2. Organic membranes

[0077] The organic film 3 is a film formed by reacting a coupling agent having amino, hydrolyzable groups, and straight-chain alkyl groups with the surface of the oxide film-coated soft magnetic powder 2. Therefore, the organic film 3 contains compounds derived from the coupling agent, i.e., hydrolysates of hydrolyzable groups, formed by the condensation reaction with the oxide film-coated soft magnetic powder 2, and compounds having amino and straight-chain alkyl groups. This imparts filling properties and good compatibility with the adhesive resin to the organic film-coated soft magnetic powder 1. Furthermore, it suppresses the hygroscopicity of the organic film-coated soft magnetic powder 1 and inhibits the reduction in filling properties associated with agglomeration.

[0078] Coupling agents are, for example, compounds represented by the following general formula (I).

[0079] [Chemical Formula 1]

[0080] In the above general formula (I), R 1 R 2 and R 3 Each can be independently a hydrogen atom, an alkoxy group, a halogen atom, or an alkyl group. Wherein, R... 1 R 2 and R 3 At least one, preferably two or three, of the atoms are alkoxy or halogen atoms that are hydrolyzable groups. 1 R 2 and R 3 They can be the same as each other, or they can be different from each other.

[0081] In the above general formula (I), -(CH2) n- It is a straight-chain alkyl group. n is preferably an integer of 1 or more and 20 or less, more preferably an integer of 1 or more and 12 or less.

[0082] In the above general formula (I), X is a functional group containing an amino group. It should be noted that functional group X may contain more than two amino groups, but from the viewpoint of compatibility with adhesive resin, it is preferable to have an amino group at the end.

[0083] In the case where the hydrolyzable group is, for example, an alkoxy group, the alkoxy group undergoes hydrolysis and condensation reactions to generate a compound derived from the coupling agent. This compound forms an organic film 3 that is bonded to the oxide film-coated soft magnetic powder 2.

[0084] The linear alkyl groups impart moisture resistance and oleophilicity to the compounds constituting the organic film 3. This suppresses the agglomeration of the soft magnetic powder 1 coated with the organic film, thus preventing a decrease in filler properties. Furthermore, the organic film 3 exhibits improved affinity with the adhesive resin. Specifically, both the amino and linear alkyl groups in the organic film 3 contribute to its compatibility with the adhesive resin.

[0085] Furthermore, the number of carbon atoms in the straight-chain alkyl group (n) is preferably an integer of 1 or more and 6 or less, and particularly preferably an integer of 3 or more and 6 or less. When the number of carbon atoms in the straight-chain alkyl group is within this range, the compound readily aligns in the organic film 3 through the interaction of the straight-chain alkyl groups with each other. This facilitates the placement of amino groups on the surface. Additionally, the aforementioned moisture resistance and oleophilicity can be sufficiently ensured, and the vacancy factor of the organic film 3 can be prevented from increasing beyond a certain point.

[0086] Examples of amino groups include primary and secondary amino groups. Among these, the amino group in the coupling agent is preferably a primary amino group. Primary amino groups, due to their excellent reactivity with, for example, epoxy groups, are particularly beneficial for compatibility with adhesive resins.

[0087] The average thickness of the organic film 3 is determined based on the molecular weight of the aforementioned compound, and as an example, it is preferably 1 nm or more and 100 nm or less, more preferably 3 nm or more and 30 nm or less. Thus, the organic film 3 becomes a monomolecular film or a molecular film of similar thickness. Therefore, the aforementioned effects brought about by the organic film 3 can be obtained, and the decrease in the magnetic properties of the soft magnetic powder 1 coated with the organic film due to excessive thickness of the organic film 3 can be suppressed.

[0088] The average thickness of the organic film 3 can be determined, for example, by qualitative and quantitative analysis along the depth direction using X-ray photoelectron spectroscopy and ion sputtering. Specifically, the concentration of the component originating from the coupling agent is investigated along the depth direction. Furthermore, the region where the concentration of the component originating from the coupling agent increases is taken as the average thickness of the organic film 3. Specifically, when the concentration changes near the boundary between the organic film 3 and the oxide-coated soft magnetic powder 2, the position corresponding to half the amount of concentration change, i.e., the midpoint between the concentration on the organic film 3 side and the concentration on the oxide-coated soft magnetic powder 2 side, is taken as the boundary, and the thickness closer to the surface side than this boundary is taken as the average thickness of the organic film 3.

[0089] 1.3. Particle size

[0090] In the cumulative particle size distribution of organic film-coated soft magnetic powder 1 obtained using a laser diffraction particle size distribution measuring device, the particle size at which the cumulative frequency is 50% from the small diameter side is set as D50.

[0091] The particle size D50 of the organic film-coated soft magnetic powder 1 is 1.0 μm or more and less than 10.0 μm, preferably 3.0 μm or more and less than 8.0 μm. Because of its small particle size, the organic film-coated soft magnetic powder 1 achieves good filling properties by reducing interparticle friction and decreasing the interparticle distance. This allows for further high-density production of pressed magnetic cores. Furthermore, if the particle size D50 of the organic film-coated soft magnetic powder 1 is within this range, it helps to suppress eddy current losses in the magnetic element.

[0092] It should be noted that when the particle size D50 is below the lower limit, the particle size becomes too small, thus increasing manufacturing difficulty and causing agglomeration, which fails to adequately improve the filling performance during powder molding. Furthermore, as the surface area increases, the amount of binder resin required for particle adhesion increases. On the other hand, when the particle size D50 is above the upper limit, depending on the amount of coupling agent added, the interparticle distance increases, which also fails to adequately improve the filling performance during powder molding.

[0093] For example, when manufacturing an oxide film-coated soft magnetic powder 2 using an atomization method, the particle size of the organic film-coated soft magnetic powder 1 can be adjusted by factors such as the supply rate of molten metal, the pressure and flow rate of water used as a cooling medium.

[0094] Alternatively, the particle size can be adjusted by classifying the manufactured powder. Examples of classification methods include dry classification such as sieving, inertial classification, centrifugal classification, and air classification, and wet classification such as sedimentation classification.

[0095] 1.4. Amount of coupling agent added

[0096] The minimum coating area of ​​the coupling agent [m 2 / g] is set as CS, and the specific surface area [m] of the oxide film-coated soft magnetic powder 2 is [m 2 / g] is set as Sm. At this time, the actual amount of coupling agent added [mass%] calculated based on the content [mass%] of the compound derived from the coupling agent is 0.5 times or more and less than 2.0 times the theoretical amount of coupling agent added CA [mass%] calculated according to the following formula, preferably 0.7 times or more and less than 1.9 times, more preferably 0.9 times or more and less than 1.8 times.

[0097] CA = Sm / CS × 100

[0098] The actual amount added [mass %] is calculated by dividing the mass of organic film 3 by the mass of organic film-coated soft magnetic powder 1. The mass of organic film 3 can be calculated, for example, by observing the particle cross-section of organic film-coated soft magnetic powder 1, calculating the area of ​​organic film 3 and the area of ​​organic film-coated soft magnetic powder 1, and then based on the known specific gravity of organic film 3 and the known specific gravity of oxide film-coated soft magnetic powder 2.

[0099] Minimum coating area of ​​coupling agent [m] 2 / g]Calculated based on the Stuart-Briegleb molecular model, for example, by the following formula.

[0100] Minimum coverage area [m 2 / g] = (78.3 × 1000) / molecular weight of coupling agent

[0101] It should be noted that sometimes the values ​​can be obtained from instruction manuals and catalogs produced by the coupling agent manufacturer. In such cases, the obtained values ​​are used instead of the calculated values.

[0102] The specific surface area of ​​the oxide film-coated soft magnetic powder 2 [m 2 The surface area ratio [g] was measured using a BET-type surface area measuring device HM1201-010 manufactured by Mounttech Co., Ltd., after removing the organic film 3 from the organic film-coated soft magnetic powder 1. The sample amount was 5g.

[0103] If the actual amount of coupling agent added is within the specified range, the amount of compound derived from the coupling agent is optimized, thus enabling the production of pressed powder with excellent filling properties, compatibility with the binder resin, and minimal strength deviation. Therefore, by using organic film-coated soft magnetic powder 1, pressed powder with high density and stable mechanical strength can be obtained.

[0104] It should be noted that when the actual amount of coupling agent added is lower than the lower limit, the ratio of amino groups and linear alkyl groups decreases, thus reducing the compatibility between the organic film-coated soft magnetic powder 1 and the binder resin, and increasing the friction between the particles of the organic film-coated soft magnetic powder 1, resulting in decreased filling capacity. Furthermore, since the occupancy factor of the organic film 3 decreases, the region with high compatibility with the binder resin becomes smaller. Therefore, the strength deviation of the pressed powder body made using the organic film-coated soft magnetic powder 1 increases. On the other hand, when the actual amount of coupling agent added is higher than the upper limit, the magnetic properties of the pressed powder body made using the organic film-coated soft magnetic powder 1 decrease. Additionally, the excessive occupancy factor of the organic film 3 leads to an increase in compounds that do not contribute to improving compatibility with the binder resin. As a result, the strength deviation of the pressed powder body made using the organic film-coated soft magnetic powder 1 increases.

[0105] It should be noted that the actual amount of coupling agent added is preferably 0.05% by mass or more and 0.30% by mass or less, more preferably 0.07% by mass or more and 0.25% by mass or less, and even more preferably 0.09% by mass or more and 0.20% by mass or less. If the actual amount of coupling agent added is within the above range, the actual amount of coupling agent added can be further optimized, so that the occurrence of insufficient or excessive coupling agent can be suppressed.

[0106] 1.5. Various characteristics

[0107] Next, the various properties of the organic film-coated soft magnetic powder 1 will be explained.

[0108] 1.5.1. Moisture content

[0109] The moisture content of the organic film-coated soft magnetic powder 1 is preferably 90 ppm or more and 1000 ppm or less by mass, more preferably 150 ppm or more and 800 ppm or less, and even more preferably 200 ppm or more and 600 ppm or less. By keeping the moisture content within this range, the organic film-coated soft magnetic powder 1 becomes less prone to moisture absorption, and its filling capacity is less likely to decrease. In addition, since rusting of the soft magnetic powder 24 caused by moisture can be suppressed, the reduction of the magnetic properties of the pressed magnetic core can be suppressed.

[0110] It should be noted that when the moisture content is below the lower limit, the filling performance may change significantly due to moisture absorption in a humid environment. As a result, the strength deviation of the pressed powder may increase. On the other hand, when the moisture content is above the upper limit, the excessive moisture reduces the filling performance of the organic film-coated soft magnetic powder 1, and the soft magnetic powder 24 may easily rust.

[0111] The moisture content of the organic membrane-coated soft magnetic powder 1 was determined as follows.

[0112] First, the organic film-coated soft magnetic powder 1 was placed in an environment with atmospheric pressure, temperature 30°C, and relative humidity of 80% for 24 hours. Next, the organic film-coated soft magnetic powder 1 was heated to 250°C and subjected to Karl Fischer chromatography-mass spectrometry. The Karl Fischer method is used to determine the moisture content under these conditions. For example, a moisture measuring device such as the CA-310 manufactured by Nitto Seiko Analytical Co., Ltd. can be used in the determination of moisture content using the Karl Fischer method.

[0113] 1.5.2. Oxygen content

[0114] The oxygen content of the organic film-coated soft magnetic powder 1 is preferably 200 ppm or more and 5000 ppm or less by mass, more preferably 250 ppm or more and 3000 ppm or less, and even more preferably 300 ppm or more and 2500 ppm or less. If the oxygen content of the organic film-coated soft magnetic powder 1 is within the above range, the tightness between the organic film 3 and the oxide film-coated soft magnetic powder 2 can be particularly improved.

[0115] It should be noted that when the oxygen content is below the lower limit, the content of hydroxyl groups reacting with the coupling agent decreases, and the tightness between the organic film 3 and the oxide film-coated soft magnetic powder 2 may decrease. On the other hand, when the oxygen content is above the upper limit, the magnetic properties of the organic film-coated soft magnetic powder 1 may decrease.

[0116] The oxygen content of the organic film-coated soft magnetic powder 1 was determined according to the general rules for quantitative methods of oxygen in metallic materials as specified in JIS Z 2613:2006. Specifically, it can be determined using oxygen / nitrogen analyzers, such as the TC-300 / EF-300 and the OH836 manufactured by LECO.

[0117] 1.5.3. Strength of the compression ring

[0118] When a molded article is obtained by coating soft magnetic powder 1 with an organic film and epoxy resin (adhesive resin), the ring strength of the resulting molded article is preferably 23 MPa or more, more preferably 25 MPa or more and 45 MPa or less, and even more preferably 27 MPa or more and 40 MPa or less. If the ring strength of the molded article is within the specified range, it is possible to manufacture an organic film-coated soft magnetic powder 1 with a pressed powder magnetic core that has a practical mechanical strength and minimal strength deviation.

[0119] It should be noted that when the ring strength of the molded body is lower than the lower limit, under strong impact, notches and cracks may occur on the pressed powder magnetic core. On the other hand, the ring strength of the molded body can also be higher than the upper limit, but in this case, the strength deviation of the pressed powder magnetic core may become larger, or the dimensional accuracy may be reduced.

[0120] It should be noted that the ring strength of the molded body was measured as follows.

[0121] First, epoxy resin, equivalent to 2.0% by mass of the organic film-coated soft magnetic powder 1, and the organic film-coated soft magnetic powder 1 were mixed and subjected to a pressure of 98.1 MPa (1.0 t / cm). 2 The ring is compressed and molded under pressure. Then, the resulting molded body is heat-treated at 600°C for 1 hour in atmospheric atmosphere. This yields a ring-shaped molded body with an outer diameter of 14 mm, an inner diameter of 8 mm, and a thickness of 3 mm. Next, the ring strength of the obtained molded body is measured. The method for measuring the ring strength is based on the ring strength test method specified in JIS Z2507:2000. Specifically, when the ring strength is set as K, the outer diameter as D, the wall thickness in the radial direction (half the difference between the outer and inner diameters) as t, the thickness as L, and the breaking load as F, the ring strength K is calculated as K = F(Dt) / (Lt). 2 Find the answer.

[0122] 2. Method for manufacturing organic film-coated soft magnetic powder

[0123] Next, the method for manufacturing the organic film-coated soft magnetic powder according to the embodiments will be described.

[0124] The method for manufacturing organic film-coated soft magnetic powder according to the embodiments includes the following steps: by hydrolyzing and condensing the soft magnetic powder 2 coated with an oxide film in the presence of a coupling agent, an organic film 3 is formed, thereby obtaining organic film-coated soft magnetic powder 1.

[0125] As previously described, the oxide film coating of the soft magnetic powder 2 comprises soft magnetic powder 24 and oxide film 26. The coupling agent comprises amino groups, hydrolyzable groups, and straight-chain alkyl groups.

[0126] In addition, the average particle size of the organic film-coated soft magnetic powder 1, as measured by a laser diffraction particle size distribution measuring device, is 1.0 μm or more and less than 10.0 μm based on volume.

[0127] Furthermore, the minimum coating area of ​​the coupling agent [m] 2 / g] is set as CS, and the specific surface area of ​​the soft magnetic powder 2 coated with oxide film is [m2 When / g] is set to Sm, the actual amount of coupling agent added [mass%] in the above process is more than 0.5 times and less than 2.0 times the theoretical amount of coupling agent added CA [mass%] calculated by the following formula, preferably more than 0.7 times and less than 1.9 times, and more preferably more than 0.9 times and less than 1.8 times.

[0128] CA = Sm / CS × 100

[0129] If the actual amount of coupling agent added is within the specified range, an organic film-coated soft magnetic powder 1 can be manufactured, which exhibits excellent filling properties and compatibility with the binder resin, and minimal deviation in strength. By using such an organic film-coated soft magnetic powder 1, a high-density powder with stable mechanical strength can be obtained.

[0130] Furthermore, the moisture content of the organic film-coated soft magnetic powder 1 is preferably 50% to 120% of the moisture content of the oxide film-coated soft magnetic powder 2, more preferably 60% to 100%. If the moisture content of the organic film-coated soft magnetic powder 1 is within this range, moisture absorption accompanying the formation of the organic film 3 can be minimized. Therefore, it is possible to achieve an organic film-coated soft magnetic powder 1 that is less prone to rusting over time and condensation accompanied by moisture absorption.

[0131] It should be noted that the moisture content of the organic film-coated soft magnetic powder 1 can also be lower than the lower limit value, but in this case, it may easily absorb moisture over time. On the other hand, if the moisture content of the organic film-coated soft magnetic powder 1 is higher than the upper limit value, it may easily rust and coagulate over time.

[0132] The moisture content of the oxide film-coated soft magnetic powder 2 was determined as follows.

[0133] First, the oxide film-coated soft magnetic powder 2 was placed in an environment with atmospheric pressure, temperature 30℃, and relative humidity 80% for 24 hours. Then, the oxide film-coated soft magnetic powder 2 was heated to 250℃ and subjected to a Karl spectroscopy... The Karl Fischer method is used to determine the moisture content under these conditions. For example, a moisture measuring device such as the CA-310 manufactured by Nitto Seiko Analytical Co., Ltd. can be used in the determination of moisture content using the Karl Fischer method.

[0134] Furthermore, the specific surface area of ​​the organic film-coated soft magnetic powder 1 is preferably 40% or more and 120% or less of the specific surface area of ​​the oxide film-coated soft magnetic powder 2, more preferably 50% or more and 100% or less. If the specific surface area of ​​the organic film-coated soft magnetic powder 1 is within the specified range, the change in specific surface area accompanying the formation of the organic film 3 can be minimized.

[0135] It should be noted that the specific surface area of ​​the organic film-coated soft magnetic powder 1 can also be lower than the lower limit value, but in this case, the film thickness of the organic film 3 may need to be increased to achieve this. On the other hand, when the specific surface area of ​​the organic film-coated soft magnetic powder 1 is higher than the upper limit value, the hygroscopicity increases, and the amount of adhesive resin used may increase.

[0136] It should be noted that the specific surface area [m²] of the organic film-coated soft magnetic powder 1 2 The surface area was measured using a BET-type surface area measuring device HM1201-010 manufactured by Mounttech Co., Ltd. The sample volume was 5g.

[0137] Furthermore, the oxygen content of the organic film-coated soft magnetic powder 1 is preferably 50% or more and 140% or less than the oxygen content of the oxide film-coated soft magnetic powder 2, more preferably 80% or more and 120% or less. When the oxygen content of the organic film-coated soft magnetic powder 1 is within this range, the variation in oxygen content relative to the oxide film-coated soft magnetic powder 2 is suppressed. Therefore, it is possible to manufacture an organic film-coated soft magnetic powder 1 that suppresses the decrease in magnetic properties accompanying the formation of the organic film 3.

[0138] It should be noted that the oxygen content of the organic film-coated soft magnetic powder 1 can also be lower than the lower limit value, but in this case, oxidation may easily occur over time. On the other hand, when the oxygen content of the organic film-coated soft magnetic powder 1 is higher than the upper limit value, oxidation occurs as the organic film 3 is formed, and the magnetic properties of the organic film-coated soft magnetic powder 1 may decrease.

[0139] The oxygen content of the oxide film-coated soft magnetic powder 2 was determined according to the general rules for quantitative methods of oxygen in metallic materials as specified in JIS Z 2613:2006. Specifically, it can be determined using oxygen / nitrogen analyzers, such as the TC-300 / EF-300 and the ONH836 manufactured by LECO.

[0140] 3. Variations

[0141] Next, a modified example of the organic film-coated soft magnetic powder according to the above embodiment will be described.

[0142] Figure 2 This is a cross-sectional view of a particle schematically representing a modified example of the organic film-coated soft magnetic powder 1 involved in the embodiment.

[0143] The following describes a modified example, but the description will focus on the differences from the described embodiment, and the same items will be omitted.

[0144] exist Figure 2 In the organic film-coated soft magnetic powder 1 shown, the oxide film-coated soft magnetic powder 2 further has an insulating coating 4 disposed on the surface of the oxide film 26.

[0145] The insulating coating 4 comprises ceramic or glass. This imparts sufficient electrical insulation to the insulating coating 4. As a result, iron losses caused by eddy currents between particles in the pressed powder can be suppressed. Furthermore, when terminals are formed on the pressed powder, the withstand voltage between the terminals can be improved.

[0146] As ceramics, examples include oxides, nitrides, carbides, sulfides, borides, etc., and one or more mixtures of these can be used. Among them, oxides are preferred. Oxides are mostly chemically stable and are useful as constituent materials of the insulating coating 4.

[0147] Examples of oxides include silicon oxide (SiO2), magnesium oxide (MgO), calcium oxide (CaO), aluminum oxide (Al2O3), titanium oxide (TiO2), zirconium oxide (ZrO2), boron oxide (B2O3), yttrium oxide (Y2O3), phosphorus oxide (P2O5), bismuth oxide (Bi2O3), zinc oxide (ZnO), tin oxide (SnO), lead oxide (PbO), lithium oxide (Li2O), sodium oxide (Na2O), potassium oxide (K2O), strontium oxide (SrO), barium oxide (BaO), gadolinium oxide (Gd2O3), lanthanum oxide (La2O3), and ytterbium oxide (Yb2O3). It should be noted that these formulations represent the proportions of each oxide, and each oxide can also be an oxide with proportions other than those mentioned above. Furthermore, the insulating coating 4 may contain two or more of these oxides.

[0148] Examples of nitrides include silicon nitride (Si3N4), aluminum nitride (AlN), boron nitride (BN), titanium nitride (TiN), and tungsten nitride (WN).

[0149] Examples of glass include sodium glass, crystal glass, quartz glass, lead glass, potassium glass, borosilicate glass, alkali-free glass, and phosphate glass.

[0150] In addition, the insulating coating 4 may also contain inorganic materials such as phosphates like magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, and cadmium phosphate, and silicates like sodium silicate.

[0151] The average thickness of the insulating coating 4 is preferably 1 nm or more and 200 nm or less, more preferably 5 nm or more and 150 nm or less, and even more preferably 10 nm or more and 100 nm or less. If the average thickness of the insulating coating 4 is within this range, the insulation properties of the insulating coating 4 can be sufficiently ensured, and the occupancy factor of the insulating coating 4 in the pressed powder can be reduced, thereby increasing the occupancy factor of the oxide film-coated soft magnetic powder 2. Furthermore, even if the surface of the oxide film-coated soft magnetic powder 2 has unevenness, if the average thickness of the insulating coating 4 is within this range, it helps to make the unevenness uniform and smooth, and approach a spherical shape. This further improves the filling properties of the organic film-coated soft magnetic powder 1.

[0152] It should be noted that when the average thickness of the insulating coating 4 is lower than the lower limit, the insulation of the insulating coating 4 becomes insufficient, and it may not be able to sufficiently smooth the surface unevenness of the oxide film-coated soft magnetic powder 2. On the other hand, when the average thickness of the insulating coating 4 is higher than the upper limit, the insulating coating 4 may become easier to peel off, or the duty cycle of the oxide film-coated soft magnetic powder 2 in the pressed powder may decrease.

[0153] It should be noted that the average thickness of the insulating coating 4 is determined, for example, by magnifying and observing the cross-section of the organic film-coated soft magnetic powder 1. Specifically, a particle of the organic film-coated soft magnetic powder 1 is cut off to prepare a cross-sectional thin-film sample. Then, the obtained cross-sectional thin-film sample is observed using a scanning transmission electron microscope, and the thickness of the insulating coating 4 is measured at at least five locations. The measured values ​​are then averaged, and this calculated result is taken as the average thickness of the insulating coating 4. The distribution range of the insulating coating 4 in the image can be more clearly confirmed, for example, by combining EDX (energy dispersive X-ray diffraction) analysis, Auger electron spectroscopy, etc.

[0154] There are no particular limitations on the method for forming the insulating coating 4. Examples include mechanochemical methods, vapor phase film formation methods, and liquid phase film formation methods. Examples of vapor phase film formation methods include plasma polymerization, ALD (Atomic Layer Deposition), CVD (Chemical Vapor Deposition), and ion plating. Examples of liquid phase film formation methods include sol-gel methods and electrolytic reduction methods.

[0155] The following will describe the mechanochemical method and the sol-gel method in turn.

[0156] 3.1. Mechanochemical method

[0157] Mechanochemical methods involve applying mechanical stress to ceramic and glass particles to alter their physicochemical properties. For example, when a mechanochemical reaction apparatus with a cylindrical chamber that has a high-speed rotating chamber and internal compression devices and blades is used, an insulating coating 4 can be formed when mechanical interactions (mechanochemical reactions) occur between the oxide film-coated soft magnetic powder 2 and ceramic particles.

[0158] It should be noted that, as a mechanical chemical reaction device, examples include the "Nobilta" (registered trademark) pulverizer and "Mechanofusion" (registered trademark) pulverizer manufactured by Hosokawa Micron Co., Ltd., and the "Hybridizer" (registered trademark) pulverizer manufactured by Nara Machinery Manufacturing Co., Ltd.

[0159] 3.2. Sol-gel method

[0160] The sol-gel method is a method for producing inorganic oxides by hydrolyzing metal alkoxides. For example, in the case of forming an insulating coating 4 by depositing silicon oxide, the hydrolysis reaction of silanolates can be utilized. The method using silanolates will be described below.

[0161] First, the oxide film-coated soft magnetic powder 2 is dispersed in an alcohol solution containing a silanol. Examples of alcohol solutions include lower alcohols such as ethanol and methanol. For instance, 10 to 50 parts by mass of alcohol are mixed relative to 1 part by mass of the silanol.

[0162] Next, ammonia water is mixed in as a catalyst to promote the reaction, causing it to hydrolyze. This results in a dehydration condensation reaction between the hydrolysates and between the hydrolysates and the silanolate, forming -Si-O-Si- bonds on the particle surface. This forms an insulating coating 4 made of silicon oxide. The insulating coating 4 can then be heated if necessary.

[0163] 4. Powder-pressed magnetic cores and magnetic components

[0164] Next, the pressed powder core and magnetic elements involved in the embodiments will be described.

[0165] The magnetic components described in the embodiments can be applied to various magnetic components with magnetic cores, such as choke coils, inductors, noise filters, reactors, transformers, motors, actuators, solenoid valves, and generators. Furthermore, the powder-pressed magnetic cores described in the embodiments can be applied to the magnetic cores of these magnetic components.

[0166] The following explanation uses two types of coil components as examples of magnetic elements.

[0167] 4.1. Circular

[0168] First, the ring-shaped coil component, which is the magnetic element involved in the embodiment, will be described.

[0169] Figure 3 This is a schematic top view representing a loop-shaped coil component. Figure 3 The coil component 10 shown has an annular pressed powder core 11 and a wire 12 wound on the pressed powder core 11.

[0170] The pressed powder magnetic core 11 is obtained by mixing the aforementioned organic film-coated soft magnetic powder 1 with a binder, feeding the resulting mixture into a molding die, and then pressing and molding it. In other words, the pressed powder magnetic core 11 is a pressed powder body containing the organic film-coated soft magnetic powder 1 described in the embodiment. In the coil component 10 equipped with such a pressed powder magnetic core 11, the strength deviation of the pressed powder magnetic core 11 is small, and the pressed powder magnetic core 11 has a high density. Therefore, when the coil component 10 is mounted in electronic devices, miniaturization, high output, and high reliability of the electronic device can be achieved.

[0171] The constituent materials of the binder used in the fabrication of the pressed powder magnetic core 11 can include, for example, organic materials such as silicone resin, epoxy resin, phenolic resin, polyamide resin, polyimide resin, and polyphenylene sulfide resin, as well as inorganic materials such as phosphates such as magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, and cadmium phosphate, and silicates such as sodium silicate.

[0172] Materials with high conductivity can be used as constituent materials for the conductor 12, such as metallic materials including Cu, Al, Ag, Au, and Ni. Additionally, an insulating film may be provided on the surface of the conductor 12 as needed.

[0173] It should be noted that the shape of the pressed powder core 11 is not limited to Figure 3 The ring shape shown can be, for example, a shape with a missing part of the ring, or a shape where the long side is a straight line.

[0174] The pressed powder core 11 may, as needed, contain soft magnetic powder and non-magnetic powder other than the organic film-coated soft magnetic powder 1 involved in the embodiments.

[0175] 3.2. Closed magnetic circuit type

[0176] Next, the closed magnetic circuit type coil component of the magnetic element involved in the embodiment will be described.

[0177] Figure 4 It is a perspective perspective view schematically representing a coil component with a closed magnetic circuit.

[0178] The following description focuses on the differences from the toroidal coil component, but the same points will be omitted.

[0179] Figure 4 The coil component 20 shown has a sheet-like pressed powder magnetic core 21 and a wire 22 embedded inside the pressed powder magnetic core 21 and formed into a coil shape. That is, the pressed powder magnetic core 21 is a pressed powder body containing the organic film-coated soft magnetic powder 1 according to the embodiment. The coil component 20 with such a pressed powder magnetic core 21 has small deviation in the strength of the pressed powder magnetic core 21 and the pressed powder magnetic core 21 has high density. Therefore, when the coil component 20 is mounted in electronic devices, it is possible to achieve miniaturization, high output, and high reliability of the electronic device.

[0180] The pressed powder core 21 may also contain soft magnetic powder and non-magnetic powder other than the organic film-coated soft magnetic powder 1 involved in the embodiments, as needed.

[0181] 4.1 Electronic devices

[0182] Next, based on Figures 5-7 The electronic equipment involved in the implementation method will be described.

[0183] Figure 5 This is a perspective view of a mobile personal computer 1100, which is an electronic device according to an embodiment. Figure 5 The personal computer 1100 shown includes: a main body 1104 with a keyboard 1102; and a display unit 1106 with a display unit 100. The display unit 1106 is rotatably supported on the main body 1104 via a hinge structure. In such a personal computer 1100, magnetic components 1000 such as choke coils and inductors for switching power supplies, and motors are built in.

[0184] Figure 6 This is a top view of a smartphone 1200, which is an electronic device involved in the implementation. Figure 6 The smartphone 1200 shown includes multiple operation buttons 1202, an earpiece 1204, and a microphone 1206. A display unit 100 is also positioned between the operation buttons 1202 and the earpiece 1204. This smartphone 1200 incorporates, for example, magnetic components 1000 such as inductors, noise filters, and motors.

[0185] Figure 7 This is a perspective view of a digital camera 1300, which is an electronic device according to this embodiment. The digital camera 1300 uses an imaging element such as a CCD (Charge Coupled Device) to perform photoelectric conversion on the light image of the subject and generate an imaging signal.

[0186] Figure 7 The digital camera 1300 shown includes a display unit 100 located on the back of the housing 1302. The display unit 100 functions as a viewfinder that displays the subject as an electronic image. Additionally, a light-receiving unit 1304, including an optical lens and a CCD, is located on the front side of the housing 1302, i.e., the back side in the figure.

[0187] When the photographer confirms the image of the subject displayed on the display unit 100 and presses the shutter button 1306, the CCD's image capture signal at that moment is transmitted and stored in the memory 1308. Such a digital camera 1300 also incorporates built-in magnetic components 1000, such as inductors and noise filters.

[0188] Such an electronic device incorporates the magnetic elements involved in the implementation method. Therefore, it is possible to benefit from the small strength deviation of the pressed powder core and the high density of such magnetic elements, achieving miniaturization, high output, and high reliability of the electronic device.

[0189] It should be noted that, as an electronic device involved in the implementation method, in addition to Figure 5 Personal computers Figure 6 smartphones, Figure 7 Besides digital cameras, other examples include mobile phones, tablets, watches, inkjet printers and other inkjet printing devices; laptop computers, televisions, video cameras, video recorders, car navigation systems, pagers, electronic notebooks, electronic dictionaries, calculators, video game consoles, word processors, workbenches, video phones, anti-theft television monitors, electronic binoculars, POS terminals, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasound diagnostic devices, electronic endoscopes and other medical equipment, fish detectors, various measuring devices, measuring instruments for vehicles, airplanes and ships, motor vehicle control equipment, aircraft control equipment, railway vehicle control equipment, ship control equipment and other mobile body control equipment, flight simulators, etc.

[0190] 5. Effects of the implementation method

[0191] As described above, the organic film-coated soft magnetic powder 1 according to the embodiment includes an oxide film-coated soft magnetic powder 2 and an organic film 3. The oxide film-coated soft magnetic powder 2 includes a soft magnetic powder 24 and an oxide film 26. The soft magnetic powder 24 is composed of a soft magnetic metal material containing Fe, Si, and B. The oxide film 26 is disposed on the surface of the soft magnetic powder 24 and contains oxides of elements contained in the soft magnetic metal material. The organic film 3 is disposed on the surface of the oxide film-coated soft magnetic powder 2 and contains a compound derived from a coupling agent having an amino group, a hydrolyzable group, and a straight-chain alkyl group located between the amino group and the hydrolyzable group. In addition, the average particle size of the organic film-coated soft magnetic powder 1, measured by a laser diffraction particle size distribution measuring device, is 1.0 μm or more and less than 10.0 μm on a volume basis. Furthermore, the minimum coating area of ​​the coupling agent [m 2 / g] is set as CS, and the specific surface area [m] of the oxide film-coated soft magnetic powder 2 is [m 2 When / g] is set as Sm, the actual amount of coupling agent added [mass%] calculated from the content [mass%] of the compound is more than 0.5 times and less than 2.0 times the theoretical amount of coupling agent added CA [mass%] calculated by the following formula.

[0192] CA = Sm / CS × 100

[0193] Based on this structure, an organic film-coated soft magnetic powder 1 can be obtained, which can produce pressed powder with excellent filling properties, compatibility with adhesive resin, and low strength deviation.

[0194] In the organic film-coated soft magnetic powder 1 described in the embodiments, the actual amount of coupling agent added is preferably 0.05% by mass or more and 0.30% by mass or less.

[0195] Based on this structure, the actual amount of coupling agent added can be further optimized, thus suppressing both insufficient and excessive coupling agents.

[0196] In the organic film-coated soft magnetic powder 1 involved in the embodiments, the amino group is preferably a primary amino group.

[0197] Based on this structure, the excellent reactivity of the primary amine with, for example, epoxy groups can particularly contribute to compatibility with adhesive resins.

[0198] In the organic film-coated soft magnetic powder 1 described in the embodiments, the number of carbon atoms in the straight-chain alkyl group is preferably 1 or more and 6 or less.

[0199] Based on this structure, compounds readily align within the organic film 3 through the interaction of straight-chain alkyl groups. This facilitates the placement of amino groups on the surface. Furthermore, sufficient moisture resistance and oleophilicity are ensured, and the vacancy factor of the organic film 3 is prevented from increasing beyond a necessary level.

[0200] In the organic film-coated soft magnetic powder 1 described in the embodiment, the oxide film-coated soft magnetic powder 2 may further have an insulating coating 4. The insulating coating 4 is disposed on the surface of the oxide film 26 and comprises ceramic or glass. In this case, an organic film 3 is disposed on the surface of the insulating coating 4.

[0201] Based on this structure, the insulating film 4 is endowed with sufficient electrical insulation. As a result, iron losses caused by eddy currents between particles in the pressed powder can be suppressed. In addition, when terminals are formed on the pressed powder, the withstand voltage between the terminals can be improved.

[0202] The method for manufacturing organic film-coated soft magnetic powder according to the embodiments includes the following steps: forming an organic film 3 containing a compound derived from a coupling agent disposed on the surface of an oxide film-coated soft magnetic powder 2, thereby obtaining organic film-coated soft magnetic powder 1. The oxide film-coated soft magnetic powder 2 has soft magnetic powder 24 and an oxide film 26. The soft magnetic powder 24 is composed of a soft magnetic metal material containing Fe, Si, and B. The oxide film 26 is disposed on the surface of the soft magnetic powder 24 and contains oxides of elements contained in the soft magnetic metal material. The coupling agent has an amino group, a hydrolyzable group, and a straight-chain alkyl group located between the amino group and the hydrolyzable group. In addition, in the above steps, in the presence of the oxide film-coated soft magnetic powder 2 and the coupling agent, the coupling agent undergoes a hydrolysis reaction and a condensation reaction. Furthermore, the average particle size of the organic film-coated soft magnetic powder 1, measured by a laser diffraction particle size distribution measuring device, is 1.0 μm or more and less than 10.0 μm on a volume basis. In addition, the minimum coating area of ​​the coupling agent [m 2 / g] is set as CS, and the specific surface area of ​​the soft magnetic powder 2 coated with oxide film is [m 2 When / g] is set to Sm, the actual amount of coupling agent added in the process [mass%] is more than 0.5 times and less than 2.0 times the theoretical amount of coupling agent added CA [mass%] calculated by the following formula.

[0203] CA = Sm / CS × 100

[0204] Based on this structure, an organic film-coated soft magnetic powder 1 can be manufactured, which can produce a pressed powder with excellent filling properties and compatibility with the binder resin, and with little deviation in strength.

[0205] In the method for manufacturing organic film-coated soft magnetic powder according to the embodiments, the moisture content of the organic film-coated soft magnetic powder 1 is preferably 50% or more and 120% or less of the moisture content of the oxide film-coated soft magnetic powder 2.

[0206] Based on this structure, moisture absorption accompanying the formation of the organic film 3 can be minimized. Therefore, it is possible to manufacture organic film-coated soft magnetic powder 1 that is less prone to rusting over time and condensation accompanied by moisture absorption.

[0207] In the method for manufacturing organic film-coated soft magnetic powder according to the embodiments, the specific surface area of ​​organic film-coated soft magnetic powder 1 is preferably 40% or more and 120% or less of the specific surface area of ​​oxide film-coated soft magnetic powder 2.

[0208] Based on this structure, the change in specific surface area accompanying the formation of organic membrane 3 can be suppressed to a minimum.

[0209] In the method for manufacturing organic film-coated soft magnetic powder according to the embodiments, the oxygen content of the organic film-coated soft magnetic powder 1 is preferably 50% or more and 140% or less of the oxygen content of the oxide film-coated soft magnetic powder 2.

[0210] Based on this structure, variations in the oxygen content relative to the oxide film-coated soft magnetic powder 2 can be suppressed. Therefore, it is possible to manufacture an organic film-coated soft magnetic powder 1 that suppresses the decrease in magnetic properties accompanying the formation of the organic film 3.

[0211] The pressed magnetic core involved in the embodiments includes the organic film-coated soft magnetic powder 1 involved in the embodiments.

[0212] Based on this structure, a pressed powder magnetic core with minimal strength deviation can be obtained.

[0213] In addition, the magnetic element involved in the embodiment includes the pressed powder magnetic core involved in the embodiment.

[0214] Based on this structure, it is possible to obtain magnetic components with small strength deviations and high density of pressed powder cores.

[0215] In addition, the electronic device according to the embodiments includes the magnetic element according to the embodiments.

[0216] Based on this structure, electronic devices that achieve miniaturization, high output, and high reliability can be obtained.

[0217] The above description, based on preferred embodiments, outlines the organic film-coated soft magnetic powder, the manufacturing method of the organic film-coated soft magnetic powder, the pressed magnetic core, the magnetic element, and the electronic device according to the present invention. However, the present invention is not limited thereto. For example, the organic film-coated soft magnetic powder, the pressed magnetic core, the magnetic element, and the electronic device according to the present invention can be replaced with any structure having the same function in each of the described embodiments, or any structure can be added to the described embodiments. Furthermore, the manufacturing method of the organic film-coated soft magnetic powder according to the present invention can also include any steps for any purpose in the described embodiments.

[0218] Furthermore, in the embodiments described above, pressed powder magnetic cores are cited as examples of applications of the organic film-coated soft magnetic powder involved in this invention, but the applications are not limited to this. For example, they can also be used as magnetic fluids, magnetic shielding sheets, magnetic heads, and other magnetic devices. In addition, the shapes of pressed powder magnetic cores and magnetic elements are not limited to the shapes shown in the figures, and can be any shape.

[0219] Example

[0220] Next, specific embodiments of the present invention will be described.

[0221] 6. Manufacturing of organic film-coated soft magnetic powder

[0222] Figure 8 Table 1 shows the composition of the organic film-coated soft magnetic powder of samples No.1 to 13. Figure 9 Table 2 shows the composition of the organic film-coated soft magnetic powder of samples No. 14 to 21. Figure 10 Table 3 shows the evaluation results of the organic film-coated soft magnetic powders of samples No.1 to No.13. Figure 11 Table 4 shows the evaluation results of the organic film-coated soft magnetic powders of samples No. 14 to 21.

[0223] 6.1. Sample No. 1

[0224] First, the raw materials are melted in a high-frequency induction furnace and then pulverized by water atomization to obtain soft magnetic powder coated with an oxide film containing an amorphous alloy.

[0225] Next, the oxide film-coated soft magnetic powder was recovered by classifying the powder using a classifier with a mesh size of 53 μm. The composition of the oxide film was analyzed by X-ray photoelectron spectroscopy (XPS), which revealed that silicon oxide was the main component.

[0226] Next, the recovered oxide-coated soft magnetic powder was surface-treated with a coupling agent to form an organic film. This yielded an organic film-coated soft magnetic powder. The composition of the obtained organic film-coated soft magnetic powder is shown in Table 1. It should be noted that a solid-state emission spectrometer manufactured by SPECTRO Corporation, model: SPECTROLAB, type: LAVMB08A, was used to determine the composition.

[0227] 6.2. Samples No. 2~21

[0228] Except for changes to the composition and manufacturing conditions of the organic film-coated soft magnetic powder as shown in Table 1 or Table 2, the organic film-coated soft magnetic powder was obtained in the same manner as in Sample No. 1.

[0229] It should be noted that the organic film-coated soft magnetic powder in samples No. 9-10 was manufactured using a rotating water jet atomization method.

[0230] In addition, the insulating coating uses a phosphate glass coating formed by a mechanochemical method.

[0231] In addition, for the manufactured organic film-coated soft magnetic powder, the particle size D50, presence or absence of insulating coating, type of coupling agent, actual amount of coupling agent added, theoretical amount of coupling agent added, and the multiple of actual amount added relative to theoretical amount of coupling agent are shown in Tables 1 and 2, respectively. It should be noted that the types of coupling agents shown in Tables 1 and 2 are as follows.

[0232] C1: 3-Aminopropyltriethoxysilane (Shin-Etsu Chemical Industry Co., Ltd., KBE-903)

[0233] [Chemical Formula 2]

[0234] C2:N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., KBM-603)

[0235] [Chemical Formula 3]

[0236] C3:3-Aminopropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., KBM-903)

[0237] [Chemical Formula 4]

[0238] C4:N-Phenyl-3-aminopropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., KBM-573)

[0239] [Chemical Formula 5]

[0240] It should be noted that in Tables 1 to 4, among the organic film-coated soft magnetic powders of each sample No., the powders equivalent to the present invention are used as "examples", and the powders not equivalent to the present invention are used as "comparative examples".

[0241] 7. Characteristics of organic film-coated soft magnetic powder

[0242] 7.1. Moisture content

[0243] For the organic film-coated soft magnetic powders of each embodiment and each comparative example, the moisture content was determined using the aforementioned method. Furthermore, the ratio of the moisture content of the organic film-coated soft magnetic powder to the moisture content of the oxide film-coated soft magnetic powder was calculated as the "change rate (%)". The calculation results are shown in Tables 3 and 4.

[0244] 7.2. Oxygen content

[0245] For the organic film-coated soft magnetic powders of each embodiment and each comparative example, the oxygen content was determined by the aforementioned method. Furthermore, the ratio of the oxygen content of the organic film-coated soft magnetic powder to the oxygen content of the oxide film-coated soft magnetic powder was calculated as the "change rate (%)". The calculation results are shown in Tables 3 and 4.

[0246] 7.3. Specific surface area

[0247] For the organic film-coated soft magnetic powders of each embodiment and each comparative example, the specific surface area was measured using the method described above. Furthermore, the ratio of the specific surface area of ​​the organic film-coated soft magnetic powder to the specific surface area of ​​the oxide film-coated soft magnetic powder was calculated as the "rate of change (%)". The calculation results are shown in Tables 3 and 4.

[0248] 8. Evaluation of organic film-coated soft magnetic powder

[0249] 8.1. Strength of the compression ring

[0250] For the organic film-coated soft magnetic powders of each embodiment and each comparative example, molded bodies for measuring the ring strength were prepared using the aforementioned method, and the ring strength was measured. The measurement results are shown in Tables 3 and 4.

[0251] 8.2. Strength Deviation

[0252] For the organic film-coated soft magnetic powders of each embodiment and comparative example, 10 molded bodies for measuring the ring strength were prepared using the aforementioned method. Then, the deviation of the measured ring strength values ​​was evaluated according to the following evaluation criteria. The evaluation results are shown in Tables 3 and 4.

[0253] A: The range of ring strength (the difference between the maximum and minimum values) is less than 1 MPa.

[0254] B: The range of ring strength (the difference between the maximum and minimum values) is above 1 MPa and less than 3 MPa.

[0255] C: The range of ring strength (the difference between the maximum and minimum values) is above 3 MPa.

[0256] 8.3. Overall Evaluation

[0257] As shown in Tables 3 and 4, by using the organic film-coated soft magnetic powder of each embodiment, it is possible to produce molded articles with high ring strength and small strength deviation. This effect can be attributed to the high filler capacity and compatibility of the organic film-coated soft magnetic powder with the adhesive resin.

Claims

1. An organic film-coated soft magnetic powder, characterized in that, have: An oxide film coats soft magnetic powder, comprising soft magnetic powder and an oxide film. The soft magnetic powder is composed of a soft magnetic metallic material containing Fe, Si, and B. The oxide film is disposed on the surface of the soft magnetic powder and comprises oxides of the elements contained in the soft magnetic metallic material. An organic film, disposed on the surface of the soft magnetic powder coated by the oxide film, comprises a compound derived from a coupling agent having an amino group, a hydrolyzable group, and a straight-chain alkyl group located between the amino group and the hydrolyzable group. The average particle size, measured by a laser diffraction particle size distribution measuring device, is greater than 1.0 μm and less than 10.0 μm based on volume. When the minimum coating area of ​​the coupling agent is set as CS and the specific surface area of ​​the soft magnetic powder coated by the oxide film is set as Sm, the actual amount of coupling agent added, calculated from the content of the compound, is more than 0.5 times and less than 2.0 times the theoretical amount of coupling agent added, CA, calculated by the following formula. CA = Sm / CS × 100 The units for both minimum coverage area and specific surface area are m. 2 / g, the content of the compound, the actual amount of the coupling agent added, and the theoretical amount of CA added are all expressed as mass% (%).

2. The organic film-coated soft magnetic powder according to claim 1, wherein, The actual amount of the coupling agent added is more than 0.05% by mass and less than 0.30% by mass.

3. The organic film-coated soft magnetic powder according to claim 1, wherein, The amino group is a primary amino group.

4. The organic film-coated soft magnetic powder according to claim 1, wherein, The linear alkyl group has 1 or more but less than 6 carbon atoms.

5. The organic film-coated soft magnetic powder according to claim 1, wherein, The oxide film coating soft magnetic powder further has an insulating coating, which is composed of ceramic or glass, disposed on the surface of the oxide film. The organic film is disposed on the surface of the insulating coating.

6. A method for manufacturing an organic film-coated soft magnetic powder, characterized in that, It has the following processes: In the presence of an oxide film-coated soft magnetic powder and a coupling agent, the coupling agent undergoes a hydrolysis and condensation reaction to form an organic film disposed on the surface of the oxide film-coated soft magnetic powder and containing compounds derived from the coupling agent. This results in an organic film-coated soft magnetic powder. The oxide film-coated soft magnetic powder comprises both soft magnetic powder and an oxide film. The soft magnetic powder is composed of a soft magnetic metal material containing Fe, Si, and B. The oxide film is disposed on the surface of the soft magnetic powder and contains oxides of the elements contained in the soft magnetic metal material. The coupling agent has an amino group, a hydrolyzable group, and a straight-chain alkyl group located between the amino group and the hydrolyzable group. The average particle size, measured by a laser diffraction particle size distribution measuring device, is greater than 1.0 μm and less than 10.0 μm based on volume. When the minimum coating area of ​​the coupling agent is set to CS and the specific surface area of ​​the soft magnetic powder coated by the oxide film is set to Sm, the actual amount of the coupling agent added in the process is more than 0.5 times and less than 2.0 times the theoretical amount CA of the coupling agent calculated by the following formula. CA = Sm / CS × 100 The units for both minimum coverage area and specific surface area are m. 2 / g, where the actual and theoretical addition amounts of the coupling agent CA are both expressed as mass% (%).

7. The method for manufacturing organic film-coated soft magnetic powder according to claim 6, wherein, The moisture content of the organic film-coated soft magnetic powder is more than 50% and less than 120% of the moisture content of the oxide film-coated soft magnetic powder.

8. The method for manufacturing organic film-coated soft magnetic powder according to claim 6, wherein, The specific surface area of ​​the organic film-coated soft magnetic powder is more than 40% and less than 120% of the specific surface area of ​​the oxide film-coated soft magnetic powder.

9. The method for manufacturing organic film-coated soft magnetic powder according to claim 6, wherein, The oxygen content of the organic film-coated soft magnetic powder is more than 50% and less than 140% of the oxygen content of the oxide film-coated soft magnetic powder.

10. A pressed powder magnetic core, characterized in that, It comprises the organic film-coated soft magnetic powder according to any one of claims 1 to 5.

11. A magnetic element, characterized in that, It has the powder-pressed magnetic core as described in claim 10.

12. An electronic device, characterized in that, It has the magnetic element as described in claim 11.

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