Organic film coated soft magnetic powder, method for producing organic film coated soft magnetic powder, compacted magnetic core, magnetic element, and electronic device.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SEIKO EPSON CORP
- Filing Date
- 2025-01-22
- Publication Date
- 2026-08-03
Smart Images
Figure 2026125315000001_ABST
Abstract
Description
[Technical Field]
[0001] The present invention relates to organic film-coated soft magnetic powder, a method for producing organic film-coated soft magnetic powder, compacted magnetic core, magnetic element, and electronic device. [Background technology]
[0002] Patent Document 1 discloses an insulating coated soft magnetic powder having a soft magnetic powder, an inorganic insulating film containing ceramics coating the particle surface of the soft magnetic powder, and an organic film containing a compound derived from a coupling agent having hydrophobic functional groups coating the surface of the inorganic insulating film.
[0003] Furthermore, Patent Document 1 discloses that the average particle size of the soft magnetic powder is 1 μm or more and 20 μm or less, and that a silane coupling agent having an NH2 group, a spacer, and a hydrolyzable group is used.
[0004] This configuration makes it possible to create an insulating coated soft magnetic powder that has excellent moisture resistance and suppresses the decrease in insulating properties and fluidity due to moisture absorption. [Prior art documents] [Patent Documents]
[0005] [Patent Document 1] Japanese Patent Publication No. 2024-140109 [Overview of the project] [Problems that the invention aims to solve]
[0006] Patent Document 1 discloses a method for forming an organic film in insulating soft magnetic powder using a silane coupling agent containing NH2 groups. However, insulating soft magnetic powder formed using this silane coupling agent has the problem of being difficult to achieve both packing ability and compatibility with the binder resin. Furthermore, there is a concern that compacts produced using such insulating soft magnetic powder will have large variations in strength. [Means for solving the problem]
[0007] The organic film-coated soft magnetic powder according to an application example of the present invention is A soft magnetic powder composed of a soft magnetic metal material containing Fe, Si, and B, and an oxide film coated soft magnetic powder having an oxide film provided on the surface of the soft magnetic powder containing oxides of the elements contained in the soft magnetic metal material, An organic film is provided on the surface of the oxide film-coated soft magnetic powder and contains a compound derived from a coupling agent having an amino group, a hydrolyzable group, and a linear alkyl group located between the amino group and the hydrolyzable group, It has, The average particle diameter measured by a laser diffraction particle size distribution analyzer is 1.0 μm or more and less than 10.0 μm. Minimum coating area of the coupling agent [m²] 2 Let / g] be CS, The specific surface area of the oxide film-coated soft magnetic powder [m²] 2 When / g] is Sm, The actual amount of the coupling agent added [mass%], determined from the content [mass%] of the aforementioned compound, is 0.5 times or more and less than 2.0 times the theoretical amount of the coupling agent added CA [mass%], which is determined by the following formula. CA = Sm / CS × 100
[0008] The method for producing organic film-coated soft magnetic powder according to an application example of the present invention is as follows: The process involves obtaining an organic film-coated soft magnetic powder, comprising: a soft magnetic powder composed of a soft magnetic metal material containing Fe, Si, and B; an oxide film provided on the surface of the soft magnetic powder containing oxides of elements contained in the soft magnetic metal material; and a coupling agent having amino groups, hydrolyzable groups, and a linear alkyl group located between the amino groups and the hydrolyzable groups, wherein the coupling agent is subjected to a hydrolysis reaction and a condensation reaction, forming an organic film on the surface of the oxide film-coated soft magnetic powder containing compounds derived from the coupling agent, thereby obtaining an organic film-coated soft magnetic powder. The average particle diameter on a volume basis measured by a laser diffraction particle size distribution measuring device is 1.0 μm or more and less than 10.0 μm, The minimum coating area [m 2 / g] of the coupling agent is defined as CS, When the specific surface area [m 2 / g] of the oxide film-coated soft magnetic powder is defined as Sm, The actual addition amount [mass%] of the coupling agent used in the above process is 0.5 times or more and less than 2.0 times the theoretical addition amount CA [mass%] of the coupling agent obtained by the following formula. CA = Sm / CS × 100
[0009] The compacted magnetic core according to the application example of the present invention contains the organic film-coated soft magnetic powder according to the application example of the present invention.
[0010] The magnetic element according to the application example of the present invention includes the compacted magnetic core according to the application example of the present invention.
[0011] The electronic device according to the application example of the present invention includes the magnetic element according to the application example of the present invention.
Brief Description of Drawings
[0012] [Figure 1] It is a cross-sectional view schematically showing one particle of the organic film-coated soft magnetic powder according to the embodiment. [Figure 2] It is a cross-sectional view schematically showing one particle of a modified example of the organic film-coated soft magnetic powder according to the embodiment. [Figure 3] It is a plan view schematically showing a toroidal type coil component. [Figure 4] It is a perspective view showing a closed magnetic circuit type coil component. [Figure 5] It is a perspective view showing a mobile personal computer which is an electronic device according to the embodiment. [Figure 6] It is a plan view showing a smartphone which is an electronic device according to the embodiment. [Figure 7]This is a perspective view showing a digital still camera, which is an electronic device according to an embodiment of this model. [Figure 8] Table 1 shows the composition of the organic film-coated soft magnetic powders of samples No. 1 to 13. [Figure 9] Table 2 shows the composition of the organic film-coated soft magnetic powders of samples No. 14 to 21. [Figure 10] Table 3 shows the evaluation results for organic film-coated soft magnetic powders of samples No. 1 to 13. [Figure 11] Table 4 shows the evaluation results for organic film-coated soft magnetic powders of samples No. 14 to 21. [Modes for carrying out the invention]
[0013] Hereinafter, the organic film-coated soft magnetic powder, the method for producing the organic film-coated soft magnetic powder, the compacted magnetic core, the magnetic element, and the electronic device according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
[0014] 1.Organic film coated soft magnetic powder First, an organic film-coated soft magnetic powder 1 according to an embodiment will be described.
[0015] Figure 1 is a schematic cross-sectional view showing one particle of the organic film-coated soft magnetic powder 1 according to an embodiment.
[0016] The organic film-coated soft magnetic powder 1 shown in Figure 1 comprises an oxide film-coated soft magnetic powder 2 and an organic film 3 provided to cover the surface of the oxide film-coated soft magnetic powder 2. In this specification, "coating" is a concept that includes not only the state in which the entire surface of the oxide film-coated soft magnetic powder 2 is covered, but also the state in which only a part of the surface is covered.
[0017] The oxide-coated soft magnetic powder 2 comprises a soft magnetic powder 24 composed of a soft magnetic metallic material containing Fe, Si, and B, and an oxide film 26 provided on the surface of the soft magnetic powder 24. The oxide film 26 contains oxides of the elements contained in the soft magnetic metallic material.
[0018] Organic film 3 contains compounds derived from a coupling agent having an amino group, a hydrolyzable group, and a linear alkyl group located between the amino group and the hydrolyzable group.
[0019] Furthermore, the average particle size of the organic film-coated soft magnetic powder 1, measured by a laser diffraction particle size distribution analyzer, is between 1.0 μm and less than 10.0 μm on a volume basis.
[0020] Furthermore, the minimum coverage area of the coupling agent [m²] 2 Let CS be [ / g], and the specific surface area [m²] of the oxide film coated soft magnetic powder 2. 2 When Sm is the amount of [ / g] of the compound, the actual amount of coupling agent added [mass%], which can be determined from the aforementioned compound content [mass%], is between 0.5 and 2.0 times the theoretical amount of coupling agent added CA [mass%], which can be determined by the following formula. CA = Sm / CS × 100
[0021] With this configuration, an organic film-coated soft magnetic powder 1 can be obtained that has excellent packing properties and compatibility with binder resins, and can produce compacts with little variation in strength. Therefore, by using the organic film-coated soft magnetic powder 1, a compact with high density and stable mechanical strength can be obtained.
[0022] 1.1. Oxide coated soft magnetic powder The oxide-coated soft magnetic powder 2 shown in Figure 1 has a soft magnetic powder 24 and an oxide film 26.
[0023] 1.1.1. Composition of soft magnetic metal materials The soft magnetic powder 24 is composed of soft magnetic metallic materials containing Fe, Si, and B.
[0024] Examples of the metal structure composed of the soft magnetic metal material include a crystal structure, an amorphous structure, a nanocrystalline structure, and the like. Among these, the soft magnetic metal material preferably includes an amorphous alloy composed of an amorphous structure or a nanocrystalline alloy composed of a nanocrystalline structure. By including these, the coercive force is reduced, contributing to the reduction of the hysteresis loss of the magnetic element. Note that in the soft magnetic metal material, structures with different crystallinities may be mixed.
[0025] Examples of the amorphous alloy material and the nanocrystalline alloy material include Fe-Si-B-based alloy materials, Fe-Si-B-C-based alloy materials, Fe-Si-B-Cr-C-based alloy materials, Fe-Co-Si-B-based alloy materials, Fe-Si-B-Nb-based alloy materials, Fe-Si-B-Nb-Cu-based alloy materials, and the like.
[0026] The soft magnetic metal material is particularly preferably an amorphous alloy material composed of the composition and impurities of the following composition formula. Thereby, an oxide film-coated soft magnetic powder 2 having both high magnetic permeability and low coercive force can be obtained.
[0027] Composition formula expressed in atomic ratio (Fe 1-x Cr x ) a (Si 1-y B y ) b C c [b is 100 - a - c. Also, 70.0 ≦ a ≦ 82.0, 0 ≦ c ≦ 4.0, 0 ≦ x ≦ 0.060, 0.30 ≦ y ≦ 0.90, That is.
[0028] The above composition formula represents the ratio in terms of the number of atoms in the composition composed of the five elements of Fe, Cr, Si, B, and C. Note that in the above composition formula, the essential elements are Fe, Si, and B.
[0029] Fe (iron) significantly affects the basic magnetic and mechanical properties of the oxide-coated soft magnetic powder 2.
[0030] The Fe content is not particularly limited, but is set such that Fe is the main component, i.e., the ratio of atoms is highest, in the oxide film-coated soft magnetic powder 2. 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.
[0031] Cr (chromium) acts to improve the corrosion resistance of the oxide-coated soft magnetic powder 2. Improved corrosion resistance suppresses oxidation, thereby preventing the deterioration of magnetic properties associated with oxidation. Furthermore, the passive film enhances insulation and contributes to suppressing eddy current losses in the oxide-coated soft magnetic powder 2.
[0032] x represents the ratio of the Cr content to the total content, where the sum of the Fe and Cr content is set to 1. In the oxide film-coated soft magnetic powder 2, x is preferably 0 ≤ x ≤ 0.060, more preferably 0.010 ≤ x ≤ 0.050, and even more preferably 0.020 ≤ x ≤ 0.040.
[0033] '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, it is preferably 70.0 ≤ a ≤ 82.0, more preferably 72.0 ≤ a ≤ 81.0, and even more preferably 73.0 ≤ a ≤ 80.5.
[0034] When manufacturing oxide-coated soft magnetic powder 2 from raw materials, silicon (Si) promotes amorphization and increases the permeability of the oxide-coated soft magnetic powder 2. This makes it possible to achieve high permeability and low coercivity.
[0035] Boron (B) promotes amorphous formation when manufacturing oxide-coated soft magnetic powder 2 from raw materials. In particular, by using Si and B together, amorphous formation can be synergistically promoted based on the difference in their atomic radii. This allows for sufficient improvement of both magnetic permeability and coercivity.
[0036] y represents the ratio of the B content to the total content, where the sum of the Si content and B content is set to 1. In the oxide film coated soft magnetic powder 2, y is preferably 0.30 ≤ y ≤ 0.90, and more preferably 0.40 ≤ y ≤ 0.80.
[0037] When the raw materials for the oxide-coated soft magnetic powder 2 are melted, carbon (C) reduces the viscosity of the molten material, facilitating amorphous and fine powder formation. This makes it possible to obtain 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 range.
[0038] c represents the carbon content when the total mass of the five elements is set to 100. In the oxide film-coated soft magnetic powder 2, c is preferably 0 ≤ c ≤ 4.0, more preferably 1.0 ≤ c ≤ 2.8, and even more preferably 1.5 ≤ c ≤ 2.5.
[0039] The composition of soft magnetic metal materials is determined by the following analytical methods. Examples of analytical methods include atomic absorption spectrometry for iron and steel as specified in JIS G 1257:2000, ICP emission spectrometry for iron and steel as specified in JIS G 1258:2007, spark discharge emission spectrometry for iron and steel as specified in JIS G 1253:2002, X-ray fluorescence spectrometry for iron and steel as specified in JIS G 1256:1997, and gravimetric titration-absorbance spectrophotometric methods as specified in JIS G 1211 to G 1237.
[0040] Specifically, examples include solid-state emission spectrometers manufactured by SPECTRO, particularly spark discharge emission spectrometers, model: SPECTROLAB, type: LAVMB08A, and the ICP instrument CIROS120 manufactured by Rigaku Corporation.
[0041] Furthermore, in particular, when identifying C (carbon) and S (sulfur), the oxygen-flow combustion (high-frequency induction heating furnace combustion)-infrared absorption method specified in JIS G 1211:2011 is also used. Specifically, the LECO CS-200 carbon-sulfur analyzer is an example.
[0042] Furthermore, when specifically identifying nitrogen (N) and oxygen (O), the methods for determining nitrogen in iron and steel specified in JIS G 1228:1997 and the general rules for determining oxygen in metallic materials specified in JIS Z 2613:2006 are also used. Specifically, the LECO TC-300 / EF-300 oxygen and nitrogen analyzer is an example.
[0043] 1.1.2. Oxide Film The oxide film 26 contains oxides of elements included in the soft magnetic metal material described above. 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.
[0044] 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.
[0045] These oxides suppress the oxidation of the soft magnetic powder 24, contributing to the suppression of the deterioration of its magnetic properties. Furthermore, these oxides have a high density of hydroxyl groups on their surface. Therefore, they contribute to improving the adhesion of the organic film 3, which will be described later.
[0046] The average thickness of the oxide film 26 is preferably 0.5 nm to 50 nm, and more preferably 1 nm to 10 nm. This further enhances the corrosion resistance of the oxide film-coated soft magnetic powder 2 and the adhesion of the organic film 3.
[0047] The average thickness of the oxide film 26 is measured, for example, by magnifying and observing the cross-section of the organic film-coated soft magnetic powder 1. Specifically, one particle of the organic film-coated soft magnetic powder 1 is cut to prepare a cross-sectional thin section sample. Next, the obtained cross-sectional thin section sample is observed using a scanning transmission electron microscope, and the thickness of the oxide film 26 is measured at five or more 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 observed image can be more clearly confirmed by using, for example, EDX analysis (energy-dispersive X-ray analysis) or Auger electron spectroscopy.
[0048] The oxide-coated soft magnetic powder 2 may be produced by any method. Examples of production methods include various atomization methods such as water atomization, gas atomization, and rotary water atomization, as well as reduction, carbonylation, and pulverization methods. Of these, atomization is preferred. Furthermore, in water atomization and rotary water atomization, pulverization is performed by contact between molten metal and water, making it easy to form an oxide film 26 of appropriate thickness on the surface of the oxide-coated soft magnetic powder 2. In addition, the rotary water atomization method can efficiently produce oxide-coated soft magnetic powder 2 with the particle size described later.
[0049] The thickness of the oxide film 26 is adjusted by the manufacturing conditions of the oxide-coated soft magnetic powder 2, such as the cooling rate of the molten metal. Specifically, slowing down the cooling rate tends to increase the thickness of the oxide film 26.
[0050] Furthermore, while it is preferable that the oxide film 26 covers the entire surface of the soft magnetic powder 24, there may be interrupted portions.
[0051] 1.2.Organic film The organic film 3 is formed by reacting a coupling agent having an amino group, a hydrolyzable group, and a linear alkyl group with the surface of the oxide-coated soft magnetic powder 2. Therefore, the organic film 3 contains compounds derived from the coupling agent, i.e., a structure formed by the condensation reaction of a hydrolyzable group's hydrolysate with the oxide-coated soft magnetic powder 2, as well as compounds having an amino group and a linear alkyl group. This imparts good packing properties and compatibility with the binder 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 prevents a decrease in packing properties of the organic film-coated soft magnetic powder 1 due to aggregation. The coupling agent is, for example, a compound represented by the following general formula (I).
[0052] [ka]
[0053] In the above general formula (I), R 1 , R 2 and R 3 Each of these is independently a hydrogen atom, an alkoxy group, a halogen atom, or an alkyl group. However, R 1 , R 2 and R 3 At least one, preferably two or three, of these is a hydrolyzable alkoxy group or halogen atom. 1 , R 2 and R 3 They may be identical to each other, or they may be different to each other.
[0054] In the above general formula (I), -(CH2) n - is a linear alkyl group. n is preferably an integer between 1 and 20, and more preferably an integer between 1 and 12.
[0055] In the above general formula (I), X is a functional group containing an amino group. The functional group X may contain two or more amino groups, but from the viewpoint of compatibility with the binder resin, it is preferable that the amino group be at the terminal end.
[0056] If the hydrolyzable group is, for example, an alkoxy group, hydrolysis and condensation reactions occur at the alkoxy group, producing a compound derived from the coupling agent. This compound forms an organic film 3 bonded to the oxide film-coated soft magnetic powder 2.
[0057] The linear alkyl group imparts moisture resistance and lipophilicity to the above-mentioned compounds constituting the organic film 3. This suppresses aggregation of the organic film-coated soft magnetic powder 1 due to moisture absorption, thereby preventing a decrease in packing performance. Furthermore, it enhances the affinity of the organic film 3 with the binder resin. In other words, both the amino group and the linear alkyl group contribute to the compatibility of the organic film 3 with the binder resin.
[0058] Furthermore, the number of carbon atoms in the linear alkyl group (n above) is more preferably an integer between 1 and 6, and particularly preferably an integer between 3 and 6. If the number of carbon atoms in the linear alkyl group is within the above range, the compounds are more likely to align in the organic film 3 due to the interaction between the linear alkyl groups. This makes it easier to position the amino group on the surface. In addition, it is possible to prevent the packing density of the organic film 3 from becoming unnecessarily large while ensuring sufficient moisture resistance and lipophilicity.
[0059] Examples of amino groups include primary amino groups and secondary amino groups. Of these, the amino group present in the coupling agent is preferably a primary amino group. Primary amino groups have excellent reactivity with epoxy groups, for example, and can therefore contribute particularly to compatibility with the binder resin.
[0060] The average thickness of the organic film 3 is determined according to the molecular weight of the compound, but as an example, it is preferably 1 nm to 100 nm, and more preferably 3 nm to 30 nm. This results in the organic film 3 being a monolayer or a near-monolayer. Therefore, the above-mentioned effects of the organic film 3 can be obtained, and the decrease in the magnetic properties of the organic film-coated soft magnetic powder 1 that occurs when the thickness of the organic film 3 becomes excessive can be suppressed.
[0061] The average thickness of the organic film 3 can be determined, for example, by qualitative and quantitative analysis in the depth direction using a combination of X-ray photoelectron spectroscopy and ion sputtering. Specifically, the concentration of components derived from the coupling agent is investigated along the depth direction. The region where the concentration of components derived from the coupling agent is high is then defined as the average thickness of the organic film 3. More specifically, when the concentration changes near the boundary between the organic film 3 and the oxide-coated soft magnetic powder 2, the boundary can be considered to be half the amount of concentration change, that is, the midpoint between the concentration on the organic film 3 side and the concentration on the oxide-coated soft magnetic powder 2 side. The thickness on the surface side of this boundary can then be defined as the average thickness of the organic film 3.
[0062] 1.3.Particle size In the volume-based cumulative particle size distribution of organic film-coated soft magnetic powder 1 obtained using a laser diffraction particle size distribution analyzer, the particle size at which the cumulative frequency from the smallest diameter side reaches 50% is defined as D50.
[0063] 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 8.0 μm or less. Because such organic film-coated soft magnetic powder 1 has a relatively small particle size, friction between particles is suppressed, reducing the distance between particles and enabling good packing. This makes it possible to further increase the density of the compacted magnetic core. In addition, if the particle size D50 of the organic film-coated soft magnetic powder 1 is within the above range, it can contribute to suppressing eddy current losses in magnetic elements.
[0064] Furthermore, if the particle size D50 falls below the lower limit, the particle size becomes too small, increasing the difficulty of manufacturing and causing aggregation, which prevents sufficient filling during compaction. In addition, the amount of binder resin required for particle bonding increases with the increase in surface area. On the other hand, if the particle size D50 exceeds the upper limit, the inter-particle distance increases depending on the amount of coupling agent added, which prevents sufficient filling during compaction.
[0065] The particle size of the organic film-coated soft magnetic powder 1 can be adjusted, for example, by the supply rate of molten metal, the pressure and flow rate of the water used as a cooling medium, when producing the oxide film-coated soft magnetic powder 2 by the atomization method.
[0066] Furthermore, the particle size may be adjusted by classifying the powder after manufacturing. Examples of classification methods include dry classification such as sieving, inertial classification, centrifugal classification, and wind classification, and wet classification such as sedimentation classification.
[0067] 1.4. Amount of coupling agent to be added Minimum coverage area of coupling agent [m²] 2 Let CS be [ / g], and the specific surface area [m²] of the oxide film coated soft magnetic powder 2. 2 Let Sm be the amount of [ / g]. In this case, the actual amount of coupling agent added [mass%], which can be determined from the content of the compound derived from the coupling agent [mass%], is 0.5 times or more and less than 2.0 times the theoretical amount of coupling agent added CA [mass%], which can be determined by the following formula, preferably 0.7 times or more and 1.9 times or less, and more preferably 0.9 times or more and 1.8 times or less. CA = Sm / CS × 100
[0068] The actual amount added [mass%] is determined by dividing the mass of the organic film 3 by the mass of the organic film-coated soft magnetic powder 1. The mass of the organic film 3 can be calculated, for example, by observing the particle cross-section of the organic film-coated soft magnetic powder 1, calculating the area of the organic film 3 and the area of the organic film-coated soft magnetic powder 1, and then using the known specific gravity of the organic film 3 and the known specific gravity of the oxide film-coated soft magnetic powder 2.
[0069] Minimum coverage area of coupling agent [m²] 2 The value [ / g] is calculated from the Stuart-briegleb molecular model and can be obtained, for example, by the following formula. Minimum coverage area [m 2 / g] = (78.3 × 1000) / Molecular weight of coupling agent
[0070] Note that this information may be available from instruction manuals or catalogs created by the coupling agent manufacturers. In such cases, you should use the obtained values rather than calculated values.
[0071] Specific surface area [m²] of oxide-coated soft magnetic powder 2 2 The specific surface area ( / g) is measured using a BET-type specific surface area analyzer HM1201-010 manufactured by Mountec Co., Ltd., after removing the organic film 3 from the organic film-coated soft magnetic powder 1. The sample volume is 5g.
[0072] If the actual amount of coupling agent added is within the aforementioned range, the amount of compounds derived from the coupling agent is optimized, making it possible to realize an organic film-coated soft magnetic powder 1 that has excellent packing properties and compatibility with binder resin, and produces compacts with little variation in strength. Therefore, by using the organic film-coated soft magnetic powder 1, compacts with high density and stable mechanical strength can be obtained.
[0073] Furthermore, if the actual amount of coupling agent added falls below the lower limit, the ratio of amino groups and linear alkyl groups decreases, reducing the compatibility between the organic film-coated soft magnetic powder 1 and the binder resin, and increasing friction between particles of the organic film-coated soft magnetic powder 1, thus reducing packing efficiency. In addition, the packing density of the organic film 3 decreases, reducing the region with high compatibility with the binder resin. As a result, the variation in strength of the compact produced using the organic film-coated soft magnetic powder 1 increases. On the other hand, if the actual amount of coupling agent added exceeds the upper limit, the magnetic properties of the compact produced using the organic film-coated soft magnetic powder 1 decrease. In addition, the packing density of the organic film 3 becomes excessive, resulting in a large amount of compounds that do not contribute to improving compatibility with the binder resin. As a result, the variation in strength of the compact produced using the organic film-coated soft magnetic powder 1 increases.
[0074] 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 amount of coupling agent added can be further optimized, thereby suppressing shortages or excesses of the coupling agent.
[0075] 1.5.Various characteristics Next, we will describe the various properties of the organic film-coated soft magnetic powder 1.
[0076] 1.5.1.Moisture content The moisture content of the organic film-coated soft magnetic powder 1 is preferably 90 ppm to 1000 ppm by mass, more preferably 150 ppm to 800 ppm, and even more preferably 200 ppm to 600 ppm. Having a moisture content within this range makes the organic film-coated soft magnetic powder 1 less susceptible to moisture absorption and less prone to a decrease in packing properties. Furthermore, it suppresses rust formation of the soft magnetic powder 24 due to moisture, thereby preventing a decrease in the magnetic properties of the compacted magnetic core.
[0077] Furthermore, if the moisture content falls below the lower limit, the packing properties may change significantly due to moisture absorption in a humid environment. As a result, there is a risk of large variations in the strength of the compacted powder. On the other hand, if the moisture content exceeds the upper limit, the packing properties of the organic film-coated soft magnetic powder 1 will decrease due to the excessive moisture content, and the soft magnetic powder 24 may become more susceptible to rusting.
[0078] The moisture content of the organic film-coated soft magnetic powder 1 is measured as follows. First, the organic film-coated soft magnetic powder 1 is left for 24 hours in an environment of atmospheric pressure, temperature of 30°C, and relative humidity of 80%. Next, the organic film-coated soft magnetic powder 1 is heated to 250°C, and the moisture content in that state is measured by the Karl Fischer method. For measuring the moisture content by the Karl Fischer method, for example, a moisture measuring device such as the CA-310 manufactured by Nitto Seikou Analytech Co., Ltd. is used.
[0079] 1.5.2.Oxygen content The oxygen content of the organic film-coated soft magnetic powder 1 is preferably 200 ppm to 5000 ppm by mass ratio, more preferably 250 ppm to 3000 ppm, and even more preferably 300 ppm to 2500 ppm. If the oxygen content of the organic film-coated soft magnetic powder 1 is within the above range, the adhesion between the organic film 3 and the oxide film-coated soft magnetic powder 2 can be particularly enhanced.
[0080] Furthermore, if the oxygen content falls below the lower limit, the content of hydroxyl groups that react with the coupling agent decreases, which may reduce the adhesion between the organic film 3 and the oxide film-coated soft magnetic powder 2. On the other hand, if the oxygen content exceeds the upper limit, the magnetic properties of the organic film-coated soft magnetic powder 1 may decrease.
[0081] The oxygen content of organic film-coated soft magnetic powder 1 is measured in accordance with the general rules for determining oxygen content in metallic materials specified in JIS Z 2613:2006. Specifically, it can be measured using LECO oxygen and nitrogen analyzers, such as the TC-300 / EF-300 or the LECO oxygen, nitrogen, and hydrogen analyzer, such as the ONH836.
[0082] 1.5.3. Compression strength When a molded body is obtained using organic film-coated soft magnetic powder 1 and epoxy resin (binder resin), the compression strength of the obtained molded body is preferably 23 MPa or higher, more preferably 25 MPa to 45 MPa, and even more preferably 27 MPa to 40 MPa. If the compression strength of the molded body is within the above range, it is possible to realize organic film-coated soft magnetic powder 1 that has a mechanical strength within a practical range and can produce compacted magnetic cores with little variation in strength.
[0083] Furthermore, if the compression strength of the molded body falls below the lower limit, a strong impact may occur on the powdered magnetic core manufactured using the organic film-coated soft magnetic powder 1, potentially causing chipping or cracking of the core. On the other hand, the compression strength of the molded body may exceed the upper limit, but in that case, there is a risk of increased variation in the strength of the powdered magnetic core or a decrease in dimensional accuracy.
[0084] The compression strength of the molded body is measured as follows. First, an epoxy resin equivalent to 2.0% by mass of the organic film-coated soft magnetic powder 1 is mixed with the organic film-coated soft magnetic powder 1, and then heated to 98.1 MPa (1.0 t / cm²). 2 The material is compressed and molded under a pressure of ). Next, the resulting molded body is heat-treated at 600°C for 1 hour in an atmospheric environment. This yields an annular molded body with an outer diameter of 14 mm, an inner diameter of 8 mm, and a thickness of 3 mm. Next, the compression strength of the resulting molded body is measured. The method for measuring the compression strength shall conform to the compression strength test method specified in JIS Z 2507:2000. Specifically, when the compression strength is K, the outer diameter is D, the radial wall thickness (half the difference between the outer and inner diameters) is t, the thickness is L, and the breaking load is F, the compression strength K is given by K = F(Dt) / (Lt). 2 It can be calculated using ).
[0085] 2. Manufacturing method of organic film-coated soft magnetic powder Next, a method for producing organic film-coated soft magnetic powder according to an embodiment will be described.
[0086] The method for producing organic film-coated soft magnetic powder according to the embodiment includes the step of obtaining organic film-coated soft magnetic powder 1 by causing a hydrolysis reaction and a condensation reaction in the presence of oxide film-coated soft magnetic powder 2 and a coupling agent to form an organic film 3.
[0087] As described above, the oxide-coated soft magnetic powder 2 comprises soft magnetic powder 24 and oxide film 26. The coupling agent has an amino group, a hydrolyzable group, and a linear alkyl group.
[0088] Furthermore, the average particle size on a volume basis of the manufactured organic film-coated soft magnetic powder 1, as measured by a laser diffraction particle size distribution analyzer, is between 1.0 μm and less than 10.0 μm.
[0089] Furthermore, the minimum coverage area of the coupling agent [m²] 2 Let CS be [ / g], and the specific surface area [m²] of the oxide film coated soft magnetic powder 2.2 When Sm is the amount of coupling agent used in the above process, the actual amount of coupling agent added [mass%] is 0.5 times or more and less than 2.0 times the theoretical amount of coupling agent added CA [mass%] calculated by the following formula, preferably 0.7 times or more and 1.9 times or less, and more preferably 0.9 times or more and 1.8 times or less. CA = Sm / CS × 100
[0090] If the actual amount of coupling agent added is within the aforementioned range, an organic film-coated soft magnetic powder 1 can be produced that has excellent packing properties and compatibility with binder resin, and produces compacts with little variation in strength. By using such an organic film-coated soft magnetic powder 1, a compact with high density and stable mechanical strength can be obtained.
[0091] Furthermore, the moisture content of the manufactured 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, and more preferably 60% to 100%. If the moisture content of the organic film-coated soft magnetic powder 1 is within the above range, moisture absorption associated with the formation of the organic film 3 can be minimized. Therefore, it is possible to realize an organic film-coated soft magnetic powder 1 that is less prone to problems such as rusting over time and aggregation due to moisture absorption.
[0092] The moisture content of the organic film-coated soft magnetic powder 1 may be below the lower limit, but in that case, it may become more susceptible to moisture absorption over time. On the other hand, if the moisture content of the organic film-coated soft magnetic powder 1 exceeds the upper limit, it may become more prone to rusting and aggregation over time.
[0093] The moisture content of the oxide-coated soft magnetic powder 2 is measured as follows. First, the oxide-coated soft magnetic powder 2 is left for 24 hours in an environment of atmospheric pressure, temperature of 30°C, and relative humidity of 80%. Next, the oxide-coated soft magnetic powder 2 is heated to 250°C, and the moisture content in that state is measured by the Karl Fischer method. For measuring the moisture content by the Karl Fischer method, for example, a moisture measuring device such as the CA-310 manufactured by Nitto Seikou Analytech Co., Ltd. is used.
[0094] Furthermore, the specific surface area of the manufactured organic film-coated soft magnetic powder 1 is preferably 40% to 120% of the specific surface area of the oxide film-coated soft magnetic powder 2, and more preferably 50% to 100%. If the specific surface area of the organic film-coated soft magnetic powder 1 is within the above range, the change in specific surface area associated with the formation of the organic film 3 can be minimized.
[0095] The specific surface area of the organic film-coated soft magnetic powder 1 may fall below the lower limit, but in that case, the thickness of the organic film 3 may increase in order to achieve this. On the other hand, if the specific surface area of the organic film-coated soft magnetic powder 1 exceeds the upper limit, the hygroscopicity will increase, and the amount of binder resin used may increase.
[0096] The specific surface area of the organic film-coated soft magnetic powder 1 is [m²]. 2 The specific surface area ( / g) is measured using a BET-type specific surface area analyzer HM1201-010 manufactured by Mountec Co., Ltd. The sample volume is 5g.
[0097] Furthermore, the oxygen content of the manufactured organic film-coated soft magnetic powder 1 is preferably 50% to 140% of the oxygen content of the oxide film-coated soft magnetic powder 2, and more preferably 80% to 120%. If the oxygen content of the organic film-coated soft magnetic powder 1 is within the above range, the variation in the 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 in which the deterioration of magnetic properties associated with the formation of the organic film 3 is suppressed.
[0098] The oxygen content of the organic film-coated soft magnetic powder 1 may fall below the lower limit, but in that case, oxidation may progress more easily over time. On the other hand, if the oxygen content of the organic film-coated soft magnetic powder 1 exceeds the upper limit, oxidation will progress as the organic film 3 is formed, and the magnetic properties of the organic film-coated soft magnetic powder 1 may deteriorate.
[0099] The oxygen content of oxide-coated soft magnetic powder 2 is measured in accordance with the general rules for determining oxygen content in metallic materials specified in JIS Z 2613:2006. Specifically, it can be measured using LECO oxygen and nitrogen analyzers, such as the TC-300 / EF-300 or the LECO oxygen, nitrogen, and hydrogen analyzer, such as the ONH836.
[0100] 3. Variant Next, a modified example of the organic film-coated soft magnetic powder according to the above embodiment will be described.
[0101] Figure 2 is a schematic cross-sectional view showing one particle of a modified example of the organic film-coated soft magnetic powder 1 according to the embodiment.
[0102] The following describes modified examples, but the explanation below will focus on the differences from the above-described embodiment, and similar matters will be omitted.
[0103] In the organic film-coated soft magnetic powder 1 shown in Figure 2, the oxide film-coated soft magnetic powder 2 further has an insulating coating 4 provided on the surface of the oxide film 26.
[0104] The insulating coating 4 contains ceramics or glass. This provides the insulating coating 4 with sufficient electrical insulation properties. As a result, iron loss caused by eddy currents between particles in the compacted powder can be suppressed. Furthermore, if terminals are formed in the compacted powder, the withstand voltage between the terminals can be increased.
[0105] Examples of ceramics include oxides, nitrides, carbides, sulfides, and borides, and one or more of these, or mixtures of two or more, are used. Of these, oxides are preferred. Oxides are often chemically stable and are useful as constituent materials for the insulating coating 4.
[0106] Examples of oxides include silicon oxide such as SiO2, magnesium oxide such as MgO, calcium oxide such as CaO, aluminum oxide such as Al2O3, titanium oxide such as TiO2, zirconium oxide such as ZrO2, boron oxide such as B2O3, yttrium oxide such as Y2O3, phosphorus oxide such as P2O5, bismuth oxide such as Bi2O3, zinc oxide such as ZnO, tin oxide such as SnO, lead oxide such as PbO, lithium oxide such as Li2O, sodium oxide such as Na2O, potassium oxide such as K2O, strontium oxide such as SrO, barium oxide such as BaO, gadolinium oxide such as Gd2O3, lanthanum oxide such as La2O3, and ytterbium oxide such as Yb2O3. Note that these compositional formulas are just examples representing the compositional ratio of each oxide, and each oxide may have a compositional ratio other than those described above. Furthermore, the insulating film 4 may contain two or more of these oxides.
[0107] Examples of nitrides include silicon nitride such as Si3N4, aluminum nitride such as AlN, boron nitride such as BN, titanium nitride such as TiN, and tungsten nitride such as WN.
[0108] Examples of glass include soda-lime glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, alkali-free glass, and phosphate glass.
[0109] In addition, the insulating coating 4 may contain inorganic materials such as phosphates like magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, and cadmium phosphate, and silicates like sodium silicate.
[0110] The average thickness of the insulating film 4 is preferably 1 nm to 200 nm, more preferably 5 nm to 150 nm, and even more preferably 10 nm to 100 nm. If the average thickness of the insulating film 4 is within the above range, the insulating properties of the insulating film 4 can be sufficiently ensured while reducing the packing density of the insulating film 4 in the compacted powder and increasing the packing density of the oxide film-coated soft magnetic powder 2. Furthermore, even if there are irregularities on the surface of the oxide film-coated soft magnetic powder 2, if the average thickness of the insulating film 4 is within the above range, it helps to smooth out the irregularities and bring it closer to a spherical shape. This further improves the packing density of the organic film-coated soft magnetic powder 1.
[0111] Furthermore, if the average thickness of the insulating film 4 falls below the lower limit, the insulating properties of the insulating film 4 may become insufficient, and the surface irregularities of the oxide film-coated soft magnetic powder 2 may not be sufficiently smoothed. On the other hand, if the average thickness of the insulating film 4 exceeds the upper limit, the insulating film 4 may become more prone to peeling, and the packing density of the oxide film-coated soft magnetic powder 2 in the compacted powder may decrease.
[0112] The average thickness of the insulating film 4 is measured, for example, by magnifying and observing the cross-section of the organic film-coated soft magnetic powder 1. Specifically, one particle of the organic film-coated soft magnetic powder 1 is cut to prepare a cross-sectional thin section sample. Next, the obtained cross-sectional thin section sample is observed using a scanning transmission electron microscope, and the thickness of the insulating film 4 is measured at five or more locations. The measured values are then averaged, and the calculated result is taken as the average thickness of the insulating film 4. The distribution range of the insulating film 4 in the observed image can be more clearly confirmed by using, for example, EDX analysis (energy-dispersive X-ray analysis) or Auger electron spectroscopy.
[0113] The method for forming the insulating film 4 is not particularly limited, but examples include mechanochemical methods, vapor phase deposition methods, and liquid phase deposition methods. Examples of vapor phase deposition methods include plasma polymerization, ALD (Atomic Layer Deposition), CVD (Chemical Vapor Deposition), and ion plating. Examples of liquid phase deposition methods include sol-gel methods and electrolytic reduction methods. The following will explain the mechanochemical method and the sol-gel method as representative examples.
[0114] 3.1. Mechanochemical Method The mechanochemical method is a method of changing the physicochemical properties of ceramic particles or glass particles by applying mechanical stress. For example, by using a mechanochemical reactor having a cylindrical chamber equipped with a compression tool and blades and rotating at high speed, a mechanical interaction (mechanochemical reaction) can be generated between oxide-coated soft magnetic powder 2 and ceramic particles, etc., to form an insulating film 4.
[0115] Examples of mechanochemical reactors include the "Nobilta" (registered trademark) pulverizer and the "Mechanofusion" (registered trademark) pulverizer manufactured by Hosokawa Micron Corporation, and the "Hybridicer" (registered trademark) pulverizer manufactured by Nara Machinery Works Co., Ltd.
[0116] 3.2. Sol-gel method The sol-gel method is a method for producing inorganic oxides by hydrolysis of metal alkoxides. For example, when forming an insulating film 4 by depositing silicon oxide, the hydrolysis reaction of silicon alkoxide can be utilized. The following describes a method using silicon alkoxide.
[0117] First, the oxide-coated soft magnetic powder 2 is dispersed in an alcohol solution containing silicon alkoxide. Examples of alcohol solutions include lower alcohols such as ethanol and methanol. For example, 10 to 50 parts by mass of alcohol can be mixed with 1 part by mass of silicon alkoxide.
[0118] Next, ammonia water is mixed in as a catalyst to accelerate the reaction, causing hydrolysis. This results in dehydration condensation reactions between the hydrolysates and between them and the silicon alkoxide, forming -Si-O-Si- bonds on the particle surface. This forms an insulating film 4 composed of silicon oxide. After that, the insulating film 4 may be heated as needed.
[0119] 4. Compacted magnetic cores and magnetic elements Next, the compacted magnetic core and magnetic element according to the embodiment will be described.
[0120] The magnetic element according to this embodiment is applicable to various magnetic elements equipped with a magnetic core, such as choke coils, inductors, noise filters, reactors, transformers, motors, actuators, solenoid valves, and generators. Furthermore, the compacted magnetic core according to this embodiment is applicable to the magnetic cores provided in these magnetic elements.
[0121] Below, we will describe two types of coil components as representative examples of magnetic elements. 4.1. Toroidal type First, a toroidal coil component, which is a magnetic element according to the embodiment, will be described.
[0122] Figure 3 is a schematic plan view of a toroidal coil component. The coil component 10 shown in Figure 3 has a ring-shaped powder core 11 and a conductor 12 wound around this powder core 11.
[0123] The compacted magnetic core 11 is obtained by mixing the aforementioned organic film-coated soft magnetic powder 1 with a binder, supplying the resulting mixture to a mold, and then pressurizing and molding it. In other words, the compacted magnetic core 11 is a compacted body containing the organic film-coated soft magnetic powder 1 according to the embodiment. A coil component 10 equipped with such a compacted magnetic core 11 has small variations in the strength of the compacted magnetic core 11 and the compacted magnetic core 11 is densely packed. Therefore, when the coil component 10 is mounted on an electronic device, it is possible to miniaturize the electronic device, increase its output power, and improve its reliability.
[0124] Examples of constituent materials for the binder used in the production of the compacted magnetic core 11 include organic materials such as silicone resins, epoxy resins, phenolic resins, polyamide resins, polyimide resins, and polyphenylene sulfide resins, and inorganic materials such as phosphates like magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, and cadmium phosphate, and silicates like sodium silicate.
[0125] The materials used to construct the conductor 12 include highly conductive materials, such as metallic materials containing Cu, Al, Ag, Au, Ni, etc. An insulating film may be provided on the surface of the conductor 12 as needed.
[0126] Furthermore, the shape of the compacted magnetic core 11 is not limited to the ring shape shown in Figure 3; for example, it may be a shape in which a part of the ring is missing, or a shape in which the longitudinal direction is straight.
[0127] The compacted magnetic core 11 may, if necessary, contain soft magnetic powders other than the organic film-coated soft magnetic powder 1 according to the embodiment, or non-magnetic powders.
[0128] 3.2. Closed Magnetic Circuit Type Next, we will describe a closed-circuit type coil component, which is a magnetic element according to the embodiment. Figure 4 is a schematic transmission perspective view showing a coil component of a closed magnetic circuit type.
[0129] The following describes closed-circuit type coil components, focusing on the differences from toroidal type coil components, and omitting explanations of similar aspects.
[0130] The coil component 20 shown in Figure 4 comprises a chip-shaped powder core 21 and a conductor 22 embedded inside the powder core 21 and formed into a coil. That is, the powder core 21 is a powder compact containing the organic film-coated soft magnetic powder 1 according to the embodiment. A coil component 20 equipped with such a powder core 21 has small variations in the strength of the powder core 21 and the powder core 21 is densely packed. Therefore, when the coil component 20 is mounted on electronic equipment, it is possible to miniaturize, increase the output power and reliability of the electronic equipment.
[0131] The compacted magnetic core 21 may, if necessary, contain soft magnetic powders other than the organic film-coated soft magnetic powder 1 according to the embodiment, or non-magnetic powders.
[0132] 4.Electronic equipment Next, the electronic device according to the embodiment will be described with reference to Figures 5 to 7.
[0133] Figure 5 is a perspective view showing a mobile personal computer 1100, which is an electronic device according to an embodiment. The personal computer 1100 shown in Figure 5 comprises a main body 1104 equipped with a keyboard 1102 and a display unit 1106 equipped with a display unit 100. The display unit 1106 is rotatably supported by the main body 1104 via a hinge structure. Such a personal computer 1100 incorporates magnetic elements 1000, such as a choke coil or inductor for a switching power supply, and a motor.
[0134] Figure 6 is a plan view showing a smartphone 1200, which is an electronic device according to the embodiment. The smartphone 1200 shown in Figure 6 is equipped with a plurality of 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. Such a smartphone 1200 incorporates magnetic elements 1000, such as an inductor, a noise filter, and a motor.
[0135] Figure 7 is a perspective view showing a digital still camera 1300, which is an electronic device according to the embodiment. The digital still camera 1300 generates an imaging signal by photoelectric conversion of the light image of the subject using an image sensor such as a CCD (Charge Coupled Device).
[0136] The digital still camera 1300 shown in Figure 7 includes a display unit 100 located on the back of the case 1302. The display unit 100 functions as a viewfinder, displaying the subject as an electronic image. A light-receiving unit 1304, including an optical lens and a CCD, is provided on the front side of the case 1302, i.e., the back side in the figure.
[0137] When the photographer confirms the subject image displayed on the display unit 100 and presses the shutter button 1306, the imaging signal from the CCD at that moment is transferred and stored in the memory 1308. Such a digital still camera 1300 also incorporates magnetic elements 1000, such as an inductor and a noise filter.
[0138] Such electronic devices are equipped with magnetic elements according to the embodiment. This allows the magnetic elements to benefit from having small variations in the intensity of the compacted magnetic core and high density, thereby enabling miniaturization, increased output, and improved reliability of the electronic devices.
[0139] In addition to the personal computer in Figure 5, the smartphone in Figure 6, and the digital still camera in Figure 7, other examples of electronic devices according to this embodiment include mobile phones, tablet terminals, watches, inkjet printers and other inkjet ejection devices, laptop personal computers, televisions, video cameras, video tape recorders, car navigation systems, pagers, electronic organizers, electronic dictionaries, calculators, electronic game consoles, word processors, workstations, video phones, security television monitors, electronic binoculars, POS terminals, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasound diagnostic devices, medical devices such as electronic endoscopes, fish finders, various measuring instruments, instruments for vehicles, aircraft, and ships, mobile control devices such as automobile control equipment, aircraft control equipment, railway vehicle control equipment, and ship control equipment, and flight simulators.
[0140] 5. Effects of the Embodiment As described above, the organic film-coated soft magnetic powder 1 according to the embodiment comprises an oxide film-coated soft magnetic powder 2 and an organic film 3. The oxide film-coated soft magnetic powder 2 comprises 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 provided 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 provided 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 linear alkyl group located between the amino group and the hydrolyzable group. Furthermore, the organic film-coated soft magnetic powder 1 has an average particle diameter on a volume basis measured by a laser diffraction particle size distribution analyzer of 1.0 μm or more and less than 10.0 μm. In addition, the minimum coating area of the coupling agent [m 2 Let CS be [ / g], and the specific surface area [m²] of the oxide film coated soft magnetic powder 2. 2 When Sm is the amount of the compound [mass%], the actual amount of coupling agent added [mass%], which can be determined from the content [mass%] of the compound, is 0.5 times or more and less than 2.0 times the theoretical amount of coupling agent added CA [mass%], which can be determined by the following formula. CA = Sm / CS × 100
[0141] With this configuration, an organic film-coated soft magnetic powder 1 can be obtained that has excellent packing properties and compatibility with binder resins, and can be manufactured into compacted powders with little variation in strength.
[0142] In the organic film-coated soft magnetic powder 1 according to the embodiment, the actual amount of coupling agent added is preferably 0.05% by mass or more and 0.30% by mass or less.
[0143] This configuration allows for a more optimized amount of coupling agent added, thereby preventing shortages or excesses of the coupling agent.
[0144] In the organic film-coated soft magnetic powder 1 according to this embodiment, the amino group is preferably a primary amino group.
[0145] With this configuration, the primary amino group exhibits excellent reactivity with, for example, epoxy groups, and can therefore contribute particularly to compatibility with the binder resin.
[0146] In the organic film-coated soft magnetic powder 1 according to the embodiment, the number of carbon atoms in the linear alkyl group is preferably 1 or more and 6 or less.
[0147] With this configuration, the interaction between linear alkyl groups facilitates the alignment of compounds within the organic film 3. This makes it easier to position amino groups on the surface. Furthermore, it is possible to prevent the packing density of the organic film 3 from becoming unnecessarily large while ensuring sufficient moisture resistance and lipophilicity.
[0148] In the organic film-coated soft magnetic powder 1 according to this embodiment, the oxide film-coated soft magnetic powder 2 may further have an insulating film 4. The insulating film 4 is provided on the surface of the oxide film 26 and includes ceramics or glass. In this case, the organic film 3 is provided on the surface of the insulating film 4.
[0149] With this configuration, the insulating coating 4 is provided with sufficient electrical insulation. As a result, iron loss caused by eddy currents between particles in the compacted powder can be suppressed. Furthermore, if terminals are formed in the compacted powder, the withstand voltage between the terminals can be increased.
[0150] The method for producing organic film-coated soft magnetic powder according to the embodiment includes the step of forming an organic film 3 on the surface of oxide film-coated soft magnetic powder 2, which contains a compound derived from a coupling agent, to obtain organic film-coated soft magnetic powder 1. The oxide film-coated soft magnetic powder 2 has 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 formed 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 linear alkyl group located between the amino group and the hydrolyzable group. The above step causes a hydrolysis reaction and a condensation reaction in the coupling agent in the presence of the oxide film-coated soft magnetic powder 2 and the coupling agent. Furthermore, the organic film-coated soft magnetic powder 1 has an average particle diameter on a volume basis measured by a laser diffraction particle size distribution analyzer of 1.0 μm or more and less than 10.0 μm. Furthermore, the minimum coating area of the coupling agent [m 2 Let CS be [ / g], and the specific surface area [m²] of the oxide film coated soft magnetic powder 2. 2 When Sm is the amount of coupling agent used in the above process, the actual amount of coupling agent added [mass%] is 0.5 times or more and less than 2.0 times the theoretical amount of coupling agent added CA [mass%] calculated by the following formula. CA = Sm / CS × 100
[0151] With this configuration, it is possible to produce an organic film-coated soft magnetic powder 1 that has excellent packing properties and compatibility with binder resins, and can be manufactured into compacted powders with little variation in strength.
[0152] In the method for producing organic film-coated soft magnetic powder according to the embodiment, it is preferable that the moisture content of the organic film-coated soft magnetic powder 1 is 50% or more and 120% or less of the moisture content of the oxide film-coated soft magnetic powder 2.
[0153] This configuration minimizes moisture absorption associated with the formation of the organic film 3. Therefore, it is possible to manufacture an organic film-coated soft magnetic powder 1 that is less prone to problems such as rusting over time or aggregation due to moisture absorption.
[0154] In the method for producing organic film-coated soft magnetic powder according to the embodiment, it is preferable that the specific surface area of the organic film-coated soft magnetic powder 1 is 40% or more and 120% or less of the specific surface area of the oxide film-coated soft magnetic powder 2.
[0155] With this configuration, the change in specific surface area associated with the formation of the organic film 3 can be minimized.
[0156] In the method for producing organic film-coated soft magnetic powder according to the embodiment, it is preferable that the oxygen content of the organic film-coated soft magnetic powder 1 is 50% or more and 140% or less of the oxygen content of the oxide film-coated soft magnetic powder 2.
[0157] With this configuration, the variation in the oxygen content of the oxide film-coated soft magnetic powder 2 is suppressed. Therefore, it is possible to produce an organic film-coated soft magnetic powder 1 in which the deterioration of magnetic properties associated with the formation of the organic film 3 is suppressed.
[0158] The compacted magnetic core according to the embodiment includes the organic film-coated soft magnetic powder 1 according to the embodiment. This configuration allows for the production of a compacted magnetic core with minimal variation in strength.
[0159] Furthermore, the magnetic element according to the above embodiment includes a compacted magnetic core according to the above embodiment. This configuration allows for the creation of a magnetic element with less variation in the strength of the compacted magnetic core and high density.
[0160] Furthermore, the electronic device according to the above embodiment includes the magnetic element according to the above embodiment. This configuration allows for the creation of electronic devices that are smaller, have higher output, and are more reliable.
[0161] The organic film-coated soft magnetic powder, method for producing the organic film-coated soft magnetic powder, compacted magnetic core, magnetic element, and electronic device according to the present invention have been described above based on preferred embodiments, but the present invention is not limited thereto. For example, the organic film-coated soft magnetic powder, compacted magnetic core, magnetic element, and electronic device according to the present invention may be in which each part of the above embodiment is replaced with any component having a similar function, or any component may be added to the above embodiment. Furthermore, the method for producing the organic film-coated soft magnetic powder according to the present invention may be in which any objective step is added to the above embodiment.
[0162] Furthermore, while the above embodiment cited compacted magnetic cores as an example of applications for the organic film-coated soft magnetic powder according to the present invention, the applications are not limited to this, and may also be magnetic devices such as magnetic fluids, magnetic shielding sheets, and magnetic heads. In addition, the shape of the compacted magnetic cores and magnetic elements is not limited to those shown in the figures, and may be any shape. [Examples]
[0163] Next, specific embodiments of the present invention will be described. 6. Production of organic film-coated soft magnetic powder Figure 8 is Table 1, showing the composition, etc., of the organic film-coated soft magnetic powders of samples No. 1 to 13. Figure 9 is Table 2, showing the composition, etc., of the organic film-coated soft magnetic powders of samples No. 14 to 21. Figure 10 is Table 3, showing the evaluation results, etc., of the organic film-coated soft magnetic powders of samples No. 1 to 13. Figure 11 is Table 4, showing the evaluation results, etc., of the organic film-coated soft magnetic powders of samples No. 14 to 21.
[0164] 6.1. Sample No. 1 First, the raw materials were melted in a high-frequency induction furnace and then powdered by water atomization to obtain an oxide-coated soft magnetic powder containing an amorphous alloy.
[0165] Next, the material was classified using a classifier with a mesh opening of 53 μm, and the oxide-coated soft magnetic powder was recovered after classification. Analysis of the oxide film composition by X-ray photoelectron spectroscopy (XPS) revealed that silicon dioxide was the main component.
[0166] Next, the recovered oxide-coated soft magnetic powder was surface-treated with a coupling agent to form an organic film. This yielded organic film-coated soft magnetic powder. The composition of the obtained organic film-coated soft magnetic powder is shown in Table 1. The composition was determined using a solid-state emission spectrometer, model: SPECTROLAB, type: LAVMB08A, manufactured by SPECTRO.
[0167] 6.2. Samples No. 2-21 Organic film-coated soft magnetic powder was obtained in the same manner as for Sample No. 1, except that the composition of the organic film-coated soft magnetic powder and the manufacturing conditions for the organic film-coated soft magnetic powder were changed as shown in Table 1 or Table 2. Furthermore, the rotary water atomization method was used in the production of the organic film-coated soft magnetic powders for samples No. 9 and 10. Furthermore, a phosphate glass coating formed by a mechanochemical method was used as the insulating coating.
[0168] Furthermore, for the manufactured organic film-coated soft magnetic powder, the particle size D50, presence or absence of insulating coating, type of coupling agent, actual and theoretical amounts of coupling agent added, and the ratio of the actual amount added to the theoretical amount are shown in Tables 1 and 2, respectively. The types of coupling agents shown in Tables 1 and 2 are as follows.
[0169] C1:3-Aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBE-903)
[0170] [ka]
[0171] C2:N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-603)
[0172] [ka]
[0173] C3:3-Aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-903)
[0174] [ka]
[0175] C4:N-phenyl-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-573)
[0176] [ka]
[0177] In Tables 1 to 4, among the organic film-coated soft magnetic powders of each sample number, those corresponding to the present invention are labeled as "Examples," and those not corresponding to the present invention are labeled as "Comparative Examples."
[0178] 7. Properties of organic film-coated soft magnetic powders 7.1.Moisture content The moisture content of the organic film-coated soft magnetic powders in each example and comparative example was measured using the method described above. 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 a "percentage change (%)". The calculation results are shown in Tables 3 and 4.
[0179] 7.2. Oxygen content The oxygen content of the organic film-coated soft magnetic powders in each example and comparative example was measured using the method described above. 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 a "percentage change (%)". The calculation results are shown in Tables 3 and 4.
[0180] 7.3.Specific surface area The specific surface area of the organic film-coated soft magnetic powders in each example and comparative example 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.
[0181] 8. Evaluation of organic film-coated soft magnetic powders 8.1. Pressure ring strength For each example and comparative example, a molded body for measuring the compression ring strength was prepared for the organic film-coated soft magnetic powder using the method described above, and the compression ring strength was measured. The measurement results are shown in Tables 3 and 4.
[0182] 8.2. Variation in strength For each example and comparative example, ten molded bodies were prepared using the method described above to measure the compression strength of the organic film-coated soft magnetic powder. Next, the measurement values of the compression strength were evaluated against the following evaluation criteria to assess the variability of the strength. The evaluation results are shown in Tables 3 and 4. A: The compression strength range (difference between maximum and minimum values) is less than 1 MPa. B: The compression strength range (difference between maximum and minimum values) is 1 MPa or more and less than 3 MPa. C: The compression strength range (difference between maximum and minimum values) is 3 MPa or more.
[0183] 8.3. Overall Rating As is clear from Tables 3 and 4, it was found that by using the organic film-coated soft magnetic powder of each example, it is possible to produce molded articles with high compression strength and low strength variation. This effect is thought to be due to the high fillability and compatibility with the binder resin of the organic film-coated soft magnetic powder. [Explanation of symbols]
[0184] 1…Organic film coated soft magnetic powder, 2…Oxide film coated soft magnetic powder, 3…Organic film, 4…Insulating film, 10…Coil component, 11…Powdered magnetic core, 12…Conducting wire, 20…Coil component, 21…Powdered magnetic core, 22…Conducting wire, 24…Soft magnetic powder, 26…Oxide film, 100…Display unit, 1000…Magnetic element, 1100…Personal computer, 1102…Keyboard, 1104…Main unit, 1106…Display unit, 1200…Smartphone, 1202…Operation buttons, 1204…Earpiece, 1206…Transmitter, 1300…Digital still camera, 1302…Case, 1304…Light receiving unit, 1306…Shutter button, 1308…Memory
Claims
1. A soft magnetic powder comprising a soft magnetic metal material containing Fe, Si, and B, and an oxide film coated soft magnetic powder having an oxide film provided on the surface of the soft magnetic powder containing oxides of the elements contained in the soft magnetic metal material, An organic film is provided on the surface of the oxide film-coated soft magnetic powder and contains a compound derived from a coupling agent having an amino group, a hydrolyzable group, and a linear alkyl group located between the amino group and the hydrolyzable group, It has, The average particle diameter on a volume basis, as measured by a laser diffraction particle size distribution analyzer, is 1.0 μm or more and less than 10.0 μm. Minimum coating area of the coupling agent [m²] ２ Let CS be [ / g] The specific surface area [m²] of the oxide film coated soft magnetic powder ２ When [ / g] is Sm, The organic film-coated soft magnetic powder is characterized in that the actual amount of coupling agent added [mass%], determined from the content [mass%] of the compound, is 0.5 times or more and less than 2.0 times the theoretical amount of coupling agent added CA [mass%], which is determined by the following formula. CA=Sm / CS×100
2. The organic film-coated soft magnetic powder according to claim 1, wherein the actual amount of the coupling agent added is 0.05% by mass or more and 0.30% by mass or less.
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 number of carbon atoms in the linear alkyl group is 1 or more and 6 or less.
5. The oxide-coated soft magnetic powder further comprises an insulating coating provided on the surface of the oxide film, which includes ceramics or glass. The organic film-coated soft magnetic powder according to claim 1, wherein the organic film is provided on the surface of the insulating coating.
6. The process includes obtaining an oxide-coated soft magnetic powder having a soft magnetic powder composed of a soft magnetic metal material containing Fe, Si, and B, and an oxide film provided on the surface of the soft magnetic powder containing oxides of elements contained in the soft magnetic metal material, and a coupling agent having an amino group, a hydrolyzable group, and a linear alkyl group located between the amino group and the hydrolyzable group, by causing a hydrolysis reaction and a condensation reaction in the coupling agent, thereby forming an organic film provided on the surface of the oxide-coated soft magnetic powder containing a compound derived from the coupling agent, and obtaining an organic film-coated soft magnetic powder. The average particle diameter on a volume basis, as measured by a laser diffraction particle size distribution analyzer, is 1.0 μm or more and less than 10.0 μm. Minimum coating area of the coupling agent [m²] ２ Let CS be [ / g] The specific surface area [m²] of the oxide film coated soft magnetic powder ２ When [ / g] is Sm, A method for producing organic film-coated soft magnetic powder, characterized in that the actual amount [mass%] of the coupling agent used in the above step is 0.5 times or more and less than 2.0 times the theoretical amount CA [mass%] of the coupling agent calculated by the following formula. CA=Sm / CS×100
7. The method for producing organic film-coated soft magnetic powder according to claim 6, wherein the moisture content of the organic film-coated soft magnetic powder is 50% or more and 120% or less of the moisture content of the oxide film-coated soft magnetic powder.
8. The method for producing organic film-coated soft magnetic powder according to claim 6, wherein the specific surface area of the organic film-coated soft magnetic powder is 40% or more and 120% or less of the specific surface area of the oxide film-coated soft magnetic powder.
9. A method for producing organic film-coated soft magnetic powder according to claim 6, wherein the oxygen content of the organic film-coated soft magnetic powder is 50% or more and 140% or less of the oxygen content of the oxide film-coated soft magnetic powder.
10. A compacted magnetic core characterized by containing the organic film-coated soft magnetic powder described in any one of claims 1 to 5.
11. A magnetic element characterized by comprising a compacted magnetic core as described in claim 10.
12. An electronic device characterized by comprising the magnetic element described in claim 11.