Insulating coated soft magnetic powder, compacted magnetic core, magnetic element, and electronic equipment

Abstract

To provide an insulating coated soft magnetic powder with good interparticle insulation and adhesion of the insulating film, a compacted magnetic core and magnetic element containing such insulating coated soft magnetic powder, and an electronic device equipped with the magnetic element. [Solution] A soft magnetic powder coated with an insulating film, comprising a soft magnetic powder composed of an amorphous alloy soft magnetic material of the Fe-Si-BC system, and an insulating film containing phosphoric acid-based glass coating the surface of the soft magnetic powder, wherein the average particle size is 15.0 μm or more and 40.0 μm or less, and the phosphoric acid-based glass is a glass mainly composed of phosphorus oxide and containing Li, and the ratio of the Li content to the P content quantified by elemental analysis, Li / P, is 0.01 or more and 0.20 or less.

Description

[Technical Field]

[0001] This invention relates to insulating coated soft magnetic powder, compacted magnetic core, magnetic element, and electronic equipment. [Background technology]

[0002] Patent Document 1 discloses an insulating coated soft magnetic powder having a particulate core made of a soft magnetic material, a first coating layer covering the core, and a second coating layer covering the first coating layer. The first coating layer is formed by mechanically fixing glass particles. The second coating layer is formed by applying a solution or dispersion of an insulating material and then drying it.

[0003] With this configuration, an insulating coated soft magnetic powder can be obtained, which has an insulating coating on its surface and can be used to manufacture compacted magnetic cores with low eddy current losses over long periods of time. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-232224 [Overview of the project] [Problems that the invention aims to solve]

[0005] In the insulating soft magnetic powder described in Patent Document 1, the insulating properties of the first coating layer are insufficient. Therefore, in compacted magnetic cores containing insulating soft magnetic powder, an increase in eddy current loss in the high-frequency range is a problem. Furthermore, there is also the issue of poor adhesion of the first coating layer.

[0006] Therefore, there is a need for insulating coated soft magnetic powders with good inter-particle insulation and good adhesion of the insulating coating. [Means for solving the problem]

[0007] The insulating coated soft magnetic powder according to an application example of the present invention is A soft magnetic powder composed of an amorphous alloy soft magnetic material of the Fe-Si-BC type, The surface of the soft magnetic powder is coated with an insulating film containing phosphate-based glass, It has, The average particle size is between 15.0 μm and 40.0 μm. The aforementioned phosphoric acid-based glass is a glass whose main component is phosphorus oxide and which contains Li. The ratio of Li content to P content, Li / P, determined by elemental analysis, is between 0.01 and 0.20.

[0008] The compacted magnetic core according to an application example of the present invention is This invention includes an insulating coated soft magnetic powder, which is an example of an application of the present invention.

[0009] A magnetic element according to an application example of the present invention is The present invention comprises a compacted magnetic core according to an example of its application.

[0010] The electronic device according to an example of the application of the present invention is The present invention comprises a magnetic element according to an example of its application. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic cross-sectional view showing one particle of the insulating soft magnetic powder according to the embodiment. [Figure 2] This is a schematic plan view showing a toroidal coil component. [Figure 3] This is a schematic, transmissive perspective view showing a closed-magnetic-circuit type coil component. [Figure 4] This is a perspective view showing a mobile personal computer, which is an electronic device according to the embodiment. [Figure 5] This is a plan view showing a smartphone, which is an electronic device according to the embodiment. [Figure 6] This is a perspective view showing a digital still camera, which is an electronic device according to an embodiment of this model. [Figure 7]Table 1 shows the compositions of amorphous alloy soft magnetic materials included in insulator-coated soft magnetic powder. [Figure 8] Table 2 shows the compositions of phosphate glass included in the insulating coating of the insulator-coated soft magnetic powder. [Figure 9] Table 3 shows the configurations and evaluation results of the insulator-coated soft magnetic powder of Sample Nos. 1 to 8. [Figure 10] Table 4 shows the configurations and evaluation results of the insulator-coated soft magnetic powder of Sample Nos. 9 to 17. [Figure 11] Table 5 shows the configurations and evaluation results of the insulator-coated soft magnetic powder of Sample Nos. 18 to 26. Mode for Carrying Out the Invention

[0012] Hereinafter, the insulator-coated soft magnetic powder, the dust core, the magnetic element and the electronic device according to the present invention will be described in detail based on the preferred embodiments shown in the accompanying drawings.

[0013] 1. Insulator-coated soft magnetic powder Figure 1 is a cross-sectional view schematically showing one particle of the insulator-coated soft magnetic powder 1 according to the embodiment. In the following description, one particle of the insulator-coated soft magnetic powder 1 is also referred to as "insulator-coated soft magnetic powder 1".

[0014] The insulator-coated soft magnetic powder 1 shown in Figure 1 includes soft magnetic powder 2 and an insulating coating 3 that covers the surface of the soft magnetic powder 2. Among these, the soft magnetic powder 2 is composed of an Fe-Si-B-C-based amorphous alloy soft magnetic material. The insulating coating 3 contains phosphate glass and insulates particles of the soft magnetic powder 2 from each other. Note that the term "coating" as used herein includes not only a state where the entire particle surface of the soft magnetic powder 2 is covered, but also a state where a part of the particle surface is covered.

[0015] The average particle diameter of the insulator-coated soft magnetic powder 1 is 15.0 µm or more and 40.0 µm or less. Further, the phosphate glass contained in the insulating coating 3 is glass containing phosphorus oxide as a main component and containing Li (lithium).

[0016] Furthermore, when the insulating coated soft magnetic powder 1 was subjected to qualitative and quantitative analysis by elemental analysis, the ratio of the Li content to the quantified P (phosphorus) content, Li / P, was between 0.01 and 0.20.

[0017] This configuration yields an insulating coated soft magnetic powder 1 with good inter-particle insulation and adhesion of the insulating coating. Therefore, in a compacted magnetic core made by compacting the insulating coated soft magnetic powder 1, the increase in eddy current loss in the high-frequency range can be suppressed. Furthermore, electrical insulation can be improved between terminals provided on the compacted magnetic core.

[0018] The following describes in detail the insulating coated soft magnetic powder 1 according to the embodiment. 1.1. Soft magnetic powder The soft magnetic powder 2 is composed of an Fe-Si-BC amorphous alloy soft magnetic material. The Fe-Si-BC amorphous alloy soft magnetic material has a composition in which Fe, Si, B, and C are essential elements and is a soft magnetic metallic material having an amorphous structure.

[0019] As an example of a composition in which Fe, Si, B, and C are essential elements, the composition formula (Fe 1-x Cr x ) a (Si 1-y B y ) b C c One example of a composition is represented by the formula shown. This compositional formula represents the ratio of atoms in a composition consisting of five elements: Fe, Cr, Si, B, and C.

[0020] Also, b is 100 - ac. Furthermore, 70.0 ≤ a ≤ 82.0, 0 <c≦4.0、 0 ≤ x ≤ 0.060, 0.30 ≤ y ≤ 0.90.

[0021] Iron (Fe) significantly influences the fundamental magnetic and mechanical properties of amorphous alloy soft magnetic materials. The Fe content is set to be as high as possible, as described above.

[0022] Cr (chromium) acts to improve the corrosion resistance of amorphous alloy soft magnetic materials. The improved corrosion resistance suppresses oxidation, and can suppress the deterioration of magnetic properties accompanying oxidation. Note that Cr is an optional element.

[0023] Si (silicon) promotes amorphization and increases magnetic permeability when an amorphous alloy soft magnetic material is produced from raw materials. In addition, Si acts as a deoxidizer, generates silicon oxide distributed on the particle surface, and contributes to improving adhesion with the insulating coating 3.

[0024] B (boron) promotes amorphization when an amorphous alloy soft magnetic material is produced from raw materials. In particular, the combined use of Si and B can synergistically promote amorphization based on the difference in atomic radii between the two elements.

[0025] C (carbon) reduces the viscosity of the melt when the raw material for the amorphous alloy soft magnetic material is melted, facilitating amorphization and pulverization. This makes it possible to obtain soft magnetic powder 2 having a small diameter and high magnetic permeability. As a result, a dust core capable of suppressing eddy current loss in a high-frequency region can be obtained.

[0026] a represents the ratio of the total content of Fe and Cr to the total mass of the five elements taken as 100. In the amorphous alloy soft magnetic material, preferably 70.0 ≦ a ≦ 82.0, more preferably 72.0 ≦ a ≦ 81.5, and still more preferably 73.0 ≦ a ≦ 81.0.

[0027] c represents the content percentage of C based on the total mass of the five elements taken as 100. In the amorphous alloy soft magnetic material, preferably 0 < c ≦ 4.0, more preferably 1.0 ≦ c ≦ 2.8, and still more preferably 1.5 ≦ c ≦ 2.5.

[0028] 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. For amorphous alloy soft magnetic materials, x is preferably 0 ≤ x ≤ 0.060, more preferably 0 ≤ x ≤ 0.050, and even more preferably 0 ≤ x ≤ 0.040.

[0029] 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. For amorphous alloy soft magnetic materials, y is preferably 0.30 ≤ y ≤ 0.90, and more preferably 0.40 ≤ y ≤ 0.80.

[0030] The above describes the composition of amorphous alloy soft magnetic materials. However, the above composition is just one example, and is not limited to the above as long as the composition contains Fe, Si, B, and C as essential elements.

[0031] The amorphous alloy soft magnetic material according to the embodiment may contain impurities consisting of other elements in addition to the elements described above. The total impurity content is preferably 1.0 mass% or less, more preferably 0.2 mass% or less, and even more preferably 0.1 mass% or less. Furthermore, the individual content of each element is preferably 0.2 mass% or less, more preferably 0.1 mass% or less, and even more preferably 0.05 mass% or less. Within this range, the presence of other elements is acceptable because the effects of the present invention are not hindered by them.

[0032] The composition of the amorphous alloy soft magnetic material according to the embodiment has been described in detail above, but the above composition and impurities can be identified by the following analytical methods.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Furthermore, when specifically identifying N (nitrogen) and O (oxygen), the methods for determining nitrogen in iron and steel as specified in JIS G 1228:1997 and the general rules for determining oxygen in metallic materials as specified in JIS Z 2613:2006 are also used. Specifically, the LECO TC-300 / EF-300 oxygen / nitrogen analyzer is an example.

[0037] 1.2. Insulating Coating The insulating coating 3 contains a phosphate-based glass and coats the soft magnetic powder 2. This phosphate-based glass is a glass mainly composed of phosphorus oxide such as P2O5 and contains Li. Furthermore, when the insulating coating soft magnetic powder 1 was subjected to qualitative and quantitative analysis by elemental analysis, the ratio of Li content to the quantified P content (Li / P) was between 0.01 and 0.20. This analytical result reflects the ratio of P to Li content in the insulating coating 3.

[0038] Because the insulating coating 3 having such a structure has good insulating properties, it contributes to the insulation between particles of the insulating soft magnetic powder 1. Furthermore, because such an insulating coating 3 has high coverage on the surface of the soft magnetic powder 2, peeling is less likely to occur and it has excellent adhesion. Due to these effects, the increase in eddy current loss in the high-frequency range can be suppressed in a compacted magnetic core made by compacting the insulating soft magnetic powder 1. In addition, electrical insulation can be improved between terminals provided on the compacted magnetic core.

[0039] Phosphorus oxide, the main component of phosphate-based glass, contributes to the formation of a glass structure with a lower softening point than silicate-based glass. This is thought to contribute to the aforementioned coating properties. Therefore, when the insulating film 3 is formed by, for example, a mechanochemical method, a highly coating insulating film 3 can be formed even with a small amount of raw materials or with a small amount of energy applied during film formation. Note that the ratio of P to O in phosphorus oxide may be a ratio other than P2O5.

[0040] In the qualitative and quantitative analysis of the insulating soft magnetic powder 1, the P content is preferably 10.0% by mass or more and 50.0% by mass or less, more preferably 15.0% by mass or more and 40.0% by mass or less, and even more preferably 20.0% by mass or more and 30.0% by mass or less. This yields an insulating coating 3 containing an amount of phosphorus oxide that is necessary and sufficient to exhibit the above effects.

[0041] On the other hand, phosphorus oxide has high reactivity between its phosphate bond (POP) and water, i.e., high hygroscopicity. When phosphorus oxide absorbs moisture, the insulating properties of insulating film 3 may decrease.

[0042] Therefore, in this embodiment, Li is added to the phosphate-based glass. In the phosphate-based glass, Li exists as lithium oxide, such as Li2O. Lithium oxide is thought to weaken intermolecular bonds in the glass structure, further reducing the softening point and viscosity of the phosphate-based glass. In particular, this effect is thought to be strong because the ionic radius of Li ions is small. As a result, the phosphate-based glass containing Li softens at a lower temperature and exhibits excellent coating properties on the surface of the soft magnetic powder 2. This results in a highly adhesive insulating film 3. Furthermore, by lowering the applied energy during the formation of the insulating film 3, the reactivity of phosphorus oxide with water can be suppressed, and as a result, the hygroscopicity of the phosphate-based glass can be reduced. From the above, by adding a predetermined amount of Li to the phosphate-based glass, the decrease in the insulating properties of the insulating film 3 can be suppressed, and the coating properties of the insulating film 3 can be improved. Note that the ratio of Li to O in lithium oxide may be a ratio other than Li2O.

[0043] Furthermore, since the soft magnetic powder 2 contains Si, the Si acting as a deoxidizing agent generates silicon oxide on the particle surface. Because this silicon oxide is a glass component, it exhibits good affinity for phosphate-based glass. This further enhances the adhesion of the insulating coating 3.

[0044] In phosphoric acid-based glass, the ratio of Li content to P content, Li / P, is 0.01 to 0.20, preferably 0.03 to 0.17, and more preferably 0.05 to 0.15.

[0045] If the Li / P ratio of the content falls below the lower limit, the amount ratio of lithium oxide to phosphorus oxide decreases, which reduces at least one of the insulating properties and adhesion of the insulating film 3. On the other hand, if the Li / P ratio of the content exceeds the upper limit, the amount ratio of lithium oxide to phosphorus oxide becomes excessive, which can easily lead to the side effect of a decrease in insulating properties and adhesion.

[0046] In the qualitative and quantitative analysis of the insulating soft magnetic powder 1, the Li content is preferably 0.5% by mass or more and 5.0% by mass or less, more preferably 1.0% by mass or more and 4.0% by mass or less, and even more preferably 1.5% by mass or more and 3.0% by mass or less. This yields an insulating coating 3 containing an amount of lithium oxide that is necessary and sufficient to exhibit the above effects.

[0047] The phosphate-based glass may also contain zinc. Zinc exists in the phosphate-based glass as zinc oxide, such as ZnO. Zinc oxide, along with phosphorus oxide, contributes to stabilizing the glass structure. Furthermore, zinc oxide slows down the hardening of the raw materials as they cool after being softened at high temperatures. This action enhances the coverage of the insulating film 3. Note that the ratio of Zn to O in the zinc oxide may be other ratios than that of ZnO.

[0048] In phosphoric acid-based glass, the ratio of Li content to Zn content, Li / Zn, is preferably 0.03 to 0.30, more preferably 0.05 to 0.25, and even more preferably 0.07 to 0.20.

[0049] If the Li / Zn content ratio falls below the lower limit, the amount ratio of lithium oxide to zinc oxide decreases, resulting in an imbalance between the two, which may reduce at least one of the insulating properties and adhesion of the insulating coating 3. On the other hand, if the Li / Zn content ratio exceeds the upper limit, the amount ratio of lithium oxide to zinc oxide becomes excessive, which may reduce the effects of adding both.

[0050] In the qualitative and quantitative analysis of the insulating soft magnetic powder 1, the Zn content is preferably 1.0% by mass or more and 20.0% by mass or less, more preferably 5.0% by mass or more and 18.0% by mass or less, and even more preferably 10.0% by mass or more and 16.0% by mass or less. This yields an insulating coating 3 containing an amount of zinc oxide that is necessary and sufficient to exhibit the above effects.

[0051] Phosphate-based glass may also contain Na. Na exists in phosphate-based glass as sodium oxide, such as Na2O. Sodium oxide, like lithium oxide, reduces the softening point and viscosity of the raw materials. The ratio of Na to O in the sodium oxide may be other than the ratio of Na2O.

[0052] In phosphate-based glass, the ratio of Li content to Na content (Li / Na) is preferably 0.05 to 0.60, more preferably 0.10 to 0.50, and even more preferably 0.15 to 0.40.

[0053] If the Li / Na ratio of the content falls below the lower limit, the amount ratio of lithium oxide to sodium oxide decreases, resulting in an imbalance between the two, which may reduce at least one of the insulating properties and adhesion of the insulating coating 3. On the other hand, if the Li / Na ratio of the content exceeds the upper limit, the amount ratio of lithium oxide to sodium oxide becomes excessive, which may reduce the effects of adding both.

[0054] In the qualitative and quantitative analysis of the insulating soft magnetic powder 1, the Na content is preferably 2.0% by mass or more and 15.0% by mass or less, more preferably 4.0% by mass or more and 11.0% by mass or less, and even more preferably 6.0% by mass or more and 9.0% by mass or less. This yields an insulating coating 3 containing an amount of sodium oxide that is necessary and sufficient to exhibit the above effects.

[0055] The phosphate-based glass may also contain Al. In the phosphate-based glass, Al exists as aluminum oxide, such as Al2O3. The aluminum oxide enhances the weather resistance of the insulating coating 3. In addition, the aluminum oxide slows down the hardening of the raw materials as they cool down after being softened at high temperatures. This effect improves the coverage of the insulating coating 3. Note that the ratio of Al to O in the aluminum oxide may be a ratio other than that of Al2O3.

[0056] In phosphate-based glass, the ratio of Li content to Al content (Li / Al) is preferably 0.20 to 2.00, more preferably 0.40 to 1.50, and even more preferably 0.60 to 1.00.

[0057] If the Li / Al content ratio falls below the lower limit, the amount ratio of lithium oxide to aluminum oxide decreases, which can lead to an imbalance between the two and a decrease in the adhesion of the insulating film 3. On the other hand, if the Li / Al content ratio exceeds the upper limit, the amount ratio of lithium oxide to aluminum oxide becomes excessive, which can reduce the effectiveness of both additions.

[0058] In the qualitative and quantitative analysis of the insulating soft magnetic powder 1, the Al content is preferably 0.5% by mass or more and 5.0% by mass or less, more preferably 1.0% by mass or more and 4.0% by mass or less, and even more preferably 2.0% by mass or more and 3.5% by mass or less. This yields an insulating coating 3 containing an amount of aluminum oxide that is necessary and sufficient to exhibit the above effects.

[0059] The phosphate-based glass may also contain Si. In the phosphate-based glass, Si exists as silicon oxide such as SiO2. As mentioned above, since silicon oxide is present on the particle surface of the soft magnetic powder 2, the inclusion of silicon oxide in the insulating film 3 increases the affinity between the insulating film 3 and the soft magnetic powder 2. This further improves the adhesion of the insulating film 3.

[0060] In the qualitative and quantitative analysis of the insulating coated soft magnetic powder 1, the Si content is preferably 0.02% by mass or more and 0.30% by mass or less, more preferably 0.04% by mass or more and 0.20% by mass or less, and even more preferably 0.06% by mass or more and 0.15% by mass or less.

[0061] If the Si content falls below the lower limit, the affinity described above may not be sufficiently obtained. On the other hand, if the Si content exceeds the upper limit, the proportion of silicon dioxide in the phosphate-based glass increases, raising the softening point of the raw materials, which may reduce the coverage of the insulating film 3.

[0062] The content of each of the above elements is quantified using various elemental analysis methods. The elemental analysis methods for each element are as follows:

[0063] P: Method using an ICP emission spectrometer as specified in JIS G 1258-3:2014 Li: Method using an ICP emission spectrometer as specified in JIS G 1258-3:2014 Zn: Zinc determination method specified in JIS M 8124:2021 Na: Sodium determination method specified in JIS M 8207:2013 Al: Method using an ICP emission spectrometer as specified in JIS G 1258-3:2014 Si: Method using an ICP emission spectrometer as specified in JIS G 1258-3:2014

[0064] Furthermore, the amount of insulating film 3 in the insulating coated soft magnetic powder 1 can be expressed as a volume fraction. The volume fraction of insulating film 3 in the insulating coated soft magnetic powder 1 is preferably 0.30 volume% to 4.00 volume%, more preferably 0.40 volume% to 2.50 volume%, and even more preferably 0.50 volume% to 1.50 volume%. This allows for the optimization of the thickness of the insulating film 3 in the insulating coated soft magnetic powder 1 having the average particle size described later. As a result, an insulating coated soft magnetic powder 1 can be obtained that has good inter-particle insulation and adhesion of the insulating film 3, and that can sufficiently increase the packing density of the soft magnetic powder 2 when compacted.

[0065] Furthermore, if the volume fraction of the insulating film 3 falls below the lower limit, the coverage of the insulating film 3 may decrease, potentially reducing the insulation between particles and the adhesion of the insulating film 3. On the other hand, if the volume fraction of the insulating film 3 exceeds the upper limit, the packing density of the soft magnetic powder 2 may decrease.

[0066] Furthermore, the volume fraction of the insulating coating 3 is measured as follows. First, the cross-section of the particles of the insulating soft magnetic powder 1 is observed using an electron microscope. Next, the ratio of the area of ​​the insulating coating 3 to the total area of ​​the particles (area fraction of the insulating coating 3) is measured. The area fraction of the insulating coating 3 obtained in this way is adopted as the volume fraction of the insulating coating 3.

[0067] 1.3.Average particle size The average particle size of the insulating soft magnetic powder 1 is particle size D50, which is the particle size where the cumulative frequency from the smallest diameter side reaches 50% in the volume-based cumulative particle size distribution of the insulating soft magnetic powder 1 obtained using a laser diffraction particle size distribution analyzer.

[0068] The average particle size of the insulating soft magnetic powder 1 is 15.0 μm or more and 40.0 μm or less, preferably 17.0 μm or more and 35.0 μm or less, and more preferably 20.0 μm or more and 30.0 μm or less. Because the insulating soft magnetic powder 1 with such an average particle size has a relatively large particle size, it has excellent fluidity, thereby enabling good packing. This makes it possible to increase the density of the compacted powder.

[0069] Furthermore, if the average particle diameter falls below the lower limit, the packing performance of the insulating soft magnetic powder 1 may decrease depending on the particle shape. On the other hand, if the average particle diameter exceeds the upper limit, the iron loss in the compacted powder may increase depending on the insulating properties of the insulating coating 3.

[0070] 1.4. Degree of Crystallinity The microstructure of amorphous alloy soft magnetic materials can be evaluated based on their degree of crystallinity. The degree of crystallinity in amorphous alloy soft magnetic materials is calculated from the spectrum obtained by X-ray diffraction analysis of the insulator-coated soft magnetic powder 1. The degree of crystallinity is calculated based on the following formula. Crystallinity = {Crystal-derived strength / (Crystal-derived strength + Amorphous-derived strength)} × 100

[0071] Furthermore, as an X-ray diffractometer, for example, the RINT2500V / PC manufactured by Rigaku Corporation is used.

[0072] The degree of crystallinity measured by this method is preferably 70% or less, more preferably 60% or less, and even more preferably 40% or less. In other words, in amorphous alloy soft magnetic materials, it is preferable that the entire material is in an amorphous state, but it may also contain crystalline structures in a volume ratio of, for example, 70% or less. This allows for the stable expression of soft magnetism derived from the amorphous structure.

[0073] 1.5. Withstand voltage When 0.7 g of the insulating coated soft magnetic powder 1 is weighed and used as a test subject, and the test subject is placed in a cylinder with an inner diameter of 8 mm and an axis in the vertical direction, and a load of 20 kgf (196 N) is applied to the test subject by sandwiching it between electrodes from above and below, the withstand voltage is measured, and preferably the withstand voltage is between 250 V and 700 V, and more preferably between 350 V and 600 V. The insulating coated soft magnetic powder 1, whose withstand voltage is within this range, contributes to the realization of a magnetic element that is small but has a high rated voltage.

[0074] Furthermore, if the withstand voltage falls below the lower limit, the rated voltage of the magnetic element may not be sufficiently increased. On the other hand, the withstand voltage may exceed the upper limit, but in that case, the variation in the withstand voltage of the magnetic element may increase. In addition, it may be necessary to increase the volume fraction of the insulating coating 3 in order to increase the withstand voltage.

[0075] The method for measuring withstand voltage is as follows: First, weigh out 0.7g of insulating coated soft magnetic powder 1 as the test subject. Next, prepare a resin cylinder with an inner diameter of 8mm and an axis in the vertical direction, and place the test subject inside. Next, sandwich the test subject between two brass electrodes from above and below. The electrodes are cylindrical in shape with an outer diameter of approximately 8mm that slide against the inner surface of the cylinder. Next, with a load of 20 [kgf] (196 [N]) applied to the test subject via the electrodes, apply a DC voltage between the electrodes. Next, measure the electrical resistance between the electrodes using a digital multimeter while increasing the voltage in 50V increments. The voltage at which the electrical resistance becomes 1MΩ or less is defined as the withstand voltage. For example, if the electrical resistance becomes 1MΩ or less when the voltage is 550V, the withstand voltage is set to 500V.

[0076] 2. Method for producing insulating soft magnetic powder Next, an example of a method for producing the insulating coated soft magnetic powder 1 according to the embodiment will be described.

[0077] First, the method for producing the soft magnetic powder 2 will be described. The soft magnetic powder 2 may be produced by any method. Examples of production methods include atomization, reduction, carbonylation, and pulverization.

[0078] The atomization method is a method for producing powder by pulverizing and cooling molten raw materials by colliding them with a high-speed spray of liquid or gas-like fluid. Atomization methods include water atomization, gas atomization, and rotary water atomization, depending on the type of coolant and equipment configuration. Of these, the rotary water atomization method is preferred for the production of soft magnetic powder 2.

[0079] In the rotary water atomization method, a coolant is injected and supplied along the inner surface of a cooling cylinder, and by swirling it along the inner surface of the cooling cylinder, a coolant layer is formed on the inner surface. Meanwhile, raw materials are melted, and the resulting molten metal is allowed to fall naturally while a jet of liquid or gas is blown onto it. When the molten metal is scattered in this way, the scattered molten metal is incorporated into the coolant layer. As a result, the scattered and pulverized molten metal is rapidly cooled and solidified, yielding a soft magnetic powder 2 with a good amorphous structure even in large diameters.

[0080] Furthermore, the manufactured soft magnetic powder 2 may be subjected to classification treatment as needed. Examples of classification treatment methods include dry classification such as sieving classification, inertial classification, centrifugal classification, and wind classification, and wet classification such as sedimentation classification. Note that the classification treatment may be performed after the formation of the insulating coating 3.

[0081] Furthermore, the manufactured soft magnetic powder 2 may be subjected to heat treatment as needed. The heat treatment is performed to relieve residual stress in the soft magnetic powder 2. The heat treatment can also form an oxide film of appropriate thickness on the particle surface of the soft magnetic powder 2. The main component of the oxide film is silicon dioxide. Note that the heat treatment may be performed after the formation of the insulating film 3.

[0082] The heat treatment temperature is preferably 350°C to 450°C, and more preferably 370°C to 430°C. The time for holding this temperature is preferably 5 minutes to 60 minutes, and more preferably 10 minutes to 30 minutes. An inert atmosphere such as a nitrogen atmosphere is preferably used for the heat treatment atmosphere. By performing the heat treatment under these conditions, an oxide film with good adhesion to the insulating coating 3 can be formed.

[0083] Next, a method for forming the insulating film 3 will be described. The method for forming the insulating film 3 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. Of these, the mechanochemical method is preferably used.

[0084] The mechanochemical method is a method of changing the physicochemical properties of phosphoric acid-based 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 induced between soft magnetic powder 2 and phosphoric acid-based glass particles to form an insulating film 3.

[0085] Examples of mechanochemical reactors include the "Nobilta" (registered trademark) pulverizer and "Mechanofusion" (registered trademark) pulverizer manufactured by Hosokawa Micron Corporation, and the "Hybridizer" (registered trademark) pulverizer manufactured by Nara Machinery Works Co., Ltd.

[0086] 3. Compacted magnetic cores and magnetic elements Next, the powdered magnetic core and magnetic element according to the embodiment will be described.

[0087] 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.

[0088] Below, we will describe two types of coil components as representative examples of magnetic elements. 3.1. Toroidal type First, a toroidal coil component, which is a magnetic element according to the embodiment, will be described.

[0089] Figure 2 is a schematic plan view showing a toroidal type coil component 10. The coil component 10 shown in Figure 2 has a ring-shaped powder core 11 and a conductor 12 wound around this powder core 11.

[0090] The compacted magnetic core 11 is obtained by mixing the aforementioned insulating coated soft magnetic powder 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 powder containing the insulating coated soft magnetic powder according to the embodiment. A coil component 10 equipped with such a compacted magnetic core 11 has good insulation between terminals, low iron loss, and good magnetic properties. For this reason, the coil component 10 can contribute to lower power consumption, miniaturization, and higher output of electronic devices.

[0091] 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.

[0092] 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.

[0093] The shape of the compacted magnetic core 11 is not limited to the ring shape shown in Figure 2; 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.

[0094] The compacted magnetic core 11 may, if necessary, contain soft magnetic powders other than the insulating coated soft magnetic powder according to the embodiment, or non-magnetic powders.

[0095] 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 3 is a schematic transmission perspective view showing a closed magnetic circuit type coil component 20.

[0096] The following description will focus on the differences between the closed-magnetic-circuit type coil component 20 and the toroidal type coil component 10, omitting explanations of similar aspects.

[0097] The coil component 20 shown in Figure 3 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 insulating coated soft magnetic powder according to the embodiment. A coil component 20 equipped with such a powder core 21 has good insulation between terminals, low iron loss, and good magnetic properties. For this reason, such a coil component 20 can contribute to lower power consumption, miniaturization, and higher output of electronic devices.

[0098] The compacted magnetic core 21 may, if necessary, contain soft magnetic powders other than the insulating coated soft magnetic powder according to the embodiment, or non-magnetic powders.

[0099] 4.Electronic equipment Next, the electronic device according to the embodiment will be described with reference to Figures 4 to 6.

[0100] Figure 4 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 4 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.

[0101] Figure 5 is a plan view showing a smartphone 1200, which is an electronic device according to an embodiment. The smartphone 1200 shown in Figure 5 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.

[0102] Figure 6 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).

[0103] The digital still camera 1300 shown in Figure 6 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.

[0104] 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.

[0105] Such electronic devices are equipped with magnetic elements according to the embodiment. This results in electronic devices that are power-efficient, miniaturized, and have high output.

[0106] In addition to the personal computer in Figure 4, the smartphone in Figure 5, and the digital still camera in Figure 6, 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.

[0107] 5. Effects of the Embodiment As described above, the insulating coated soft magnetic powder 1 according to the embodiment comprises soft magnetic powder 2 and an insulating coating 3. The soft magnetic powder 2 is composed of an Fe-Si-BC amorphous alloy soft magnetic material. The insulating coating 3 coats the surface of the soft magnetic powder 2 and contains phosphoric acid-based glass. The average particle size of the insulating coated soft magnetic powder 1 is 15.0 μm or more and 40.0 μm or less. Furthermore, the phosphoric acid-based glass is a glass mainly composed of phosphorus oxide and containing Li. The ratio of the Li content to the P content, Li / P, of the insulating coated soft magnetic powder 1, as quantified by elemental analysis, is 0.01 or more and 0.20 or less.

[0108] This configuration yields an insulating coated soft magnetic powder 1 with good inter-particle insulation and adhesion of the insulating coating. Therefore, in a compacted magnetic core made by compacting the insulating coated soft magnetic powder 1, the increase in eddy current loss in the high-frequency range can be suppressed. Furthermore, electrical insulation can be improved between terminals provided on the compacted magnetic core.

[0109] In the insulating coated soft magnetic powder 1 according to the above embodiment, the phosphoric acid-based glass may further contain Zn. In this case, the ratio of the Li content to the Zn content quantified by elemental analysis, Li / Zn, is preferably 0.03 or more and 0.30 or less.

[0110] In this configuration, zinc oxide, along with phosphorus oxide, contributes to stabilizing the glass structure. Therefore, zinc oxide slows down the hardening of the raw materials as they cool after being softened at high temperatures. This effect enhances the coverage of the insulating film 3.

[0111] In the insulating coated soft magnetic powder 1 according to the above embodiment, the phosphoric acid-based glass may further contain Na. In this case, the ratio of the Li content to the Na content quantified by elemental analysis, Li / Na, is preferably 0.05 or more and 0.60 or less.

[0112] With this configuration, sodium oxide, like lithium oxide, can lower the softening point and viscosity of the raw materials.

[0113] In the insulating coated soft magnetic powder 1 according to the above embodiment, when 0.7 g of the weighed sample is used as the test subject, the sample is placed in a cylinder with an inner diameter of 8 mm and an axis in the vertical direction, and the withstand voltage is measured while the sample is sandwiched between electrodes from above and below and a load of 20 [kgf] (196 [N]) is applied to the sample, it is preferable that the withstand voltage is 250 [V] or more and 700 [V] or less.

[0114] This configuration yields an insulating coated soft magnetic powder 1 that contributes to the realization of a small magnetic element with a high rated voltage.

[0115] In the insulating coated soft magnetic powder 1 according to the above embodiment, the volume fraction of the insulating film 3 is preferably 0.30 volume% or more and 4.00 volume% or less.

[0116] With this configuration, the thickness of the insulating film 3 can be optimized in the insulating coated soft magnetic powder 1 having the aforementioned average particle size. As a result, an insulating coated soft magnetic powder 1 can be obtained that has good inter-particle insulation and adhesion of the insulating film 3, and that can sufficiently increase the packing factor of the soft magnetic powder 2 when compacted.

[0117] The compacted magnetic core according to the embodiment includes the insulating coated soft magnetic powder 1 according to the embodiment. With this configuration, a powder core can be obtained that enables the realization of a magnetic element with good insulation between terminals, low iron loss, and good magnetic properties.

[0118] Furthermore, the magnetic element according to the above embodiment includes a compacted magnetic core according to the above embodiment. With this configuration, a magnetic element can be obtained that has good insulation between terminals, low iron loss, and good magnetic properties.

[0119] 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 low-power, miniaturized, and high-power.

[0120] The insulating 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 compacted magnetic core and magnetic element 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.

[0121] Furthermore, although the above embodiment described a compacted magnetic core as an example of an application of the insulating coated soft magnetic powder according to the present invention, the application examples are not limited to this, and may also include magnetic fluids, magnetic shielding sheets, magnetic heads, and other magnetic devices. In addition, the shape of the compacted magnetic core and magnetic element is not limited to those shown in the figures, and may be any shape. [Examples]

[0122] Next, specific embodiments of the present invention will be described. 6. Manufacturing of insulating coated soft magnetic powder Figure 7 is Table 1, which shows the composition of amorphous alloy soft magnetic materials contained in insulating coated soft magnetic powder. Figure 8 is Table 2, which shows the composition of the phosphoric acid-based glass contained in the insulating coating of the insulating soft magnetic powder. Figure 9 is shown in Table 3, which illustrates the composition and evaluation results of the insulating soft magnetic powders for samples No. 1 to 8. Figure 10 is Table 4, which shows the composition and evaluation results of the insulating coated soft magnetic powders for samples No. 9 to 17. Figure 11 is shown in Table 5, which illustrates the composition and evaluation results of the insulating soft magnetic powders for samples No. 18 to 26.

[0123] 6.1. Samples No. 1-7 First, the raw materials were melted in a high-frequency induction furnace and then powdered using a rotary water atomization method to obtain metal powder.

[0124] Next, the obtained metal powder was subjected to heat treatment. The heating temperature was 410°C, the heating time was 15 minutes, and the furnace atmosphere was a nitrogen atmosphere.

[0125] Next, classification was performed using a classifier with a mesh opening of 53 μm. The classified metal powder was recovered as soft magnetic powder. The composition of the recovered soft magnetic powder is shown in Table 1. A solid-state emission spectrometer, model: SPECTROLAB, type: LAVMB08A, manufactured by SPECTRO, was used to determine the composition.

[0126] Next, an insulating film was formed on the surface of the soft magnetic powder. This yielded insulating coated soft magnetic powders No. 1 to 7. A mechanochemical method was used to form the insulating film. The composition of the phosphate-based glass contained in the insulating film is shown in Table 2.

[0127] Next, the content of P, Li, Zn, Na, Al, and Si in the insulating film was measured using the method described above. The content ratios Li / P, Li / Zn, Li / Na, and Li / Al were then calculated. The calculation results are shown in Tables 3 to 5. The measurement results for the Si content are also shown in Tables 3 to 5.

[0128] Next, the volume fraction of the insulating coating was calculated using the method described above. The calculation results are shown in Tables 3 to 5.

[0129] 6.2. Sample No. 8 The formation of an insulating film was omitted, and the amorphous alloy soft magnetic powder was used as is for Sample No. 8.

[0130] 6.3. Samples No. 9-17 Samples No. 9 to 17 were obtained in the same manner as samples No. 1 to 7, except that the composition of the insulating coated soft magnetic powder was changed as shown in Table 4.

[0131] 6.4. Samples No. 18-23 Samples No. 18 to 23 were obtained in the same manner as samples No. 1 to 7, except that the composition of the insulating coated soft magnetic powder was changed as shown in Table 5.

[0132] 6.5. Sample No. 24 The formation of an insulating coating was omitted, and the amorphous alloy soft magnetic powder was used as is for Sample No. 24.

[0133] 6.6. Sample No. 25-26 Samples No. 25-26 were obtained in the same manner as samples No. 1-7, except that the composition of the insulating coated soft magnetic powder was changed as shown in Table 5.

[0134] In Tables 3 to 5, examples corresponding to the present invention are labeled "Examples," while examples not corresponding to the present invention are labeled "Comparative Examples."

[0135] 7. Evaluation of Insulator-Coated Soft Magnetic Powder The following evaluation was performed on the insulator-coated soft magnetic powder of each sample No.

[0136] 7.1. Withstand Voltage Withstand voltage was measured by the method described above for test specimens produced from the insulator-coated soft magnetic powder of each sample No. The measurement results were evaluated against the following evaluation criteria. The evaluation results are shown in Tables 3 to 5.

[0137] A: Withstand voltage is 350 V or higher B: Withstand voltage is 300 V or higher and lower than 350 V C: Withstand voltage is 250 V or higher and lower than 300 V D: Withstand voltage is lower than 250 V

[0138] 7.2. Iron Loss Reduction Rate For the soft magnetic powder (powder before forming an insulating coating) used to produce the insulator-coated soft magnetic powder of each sample No., iron loss [kW / m 3 was measured by the following method. This measurement result is defined as "iron loss P1".

[0139] First, an amount of epoxy resin corresponding to 2.0 mass% of the soft magnetic powder was mixed with the soft magnetic powder, and the obtained mixture was warm-compacted at a temperature of 70°C and a pressure of 49.0 MPa (0.5 t / cm 2 ). Thereby, a ring-shaped compact having an outer diameter of 14 mm, an inner diameter of 8 mm, and a thickness of 3 mm was obtained. Next, a copper wire with a wire diameter of 0.16 mm was wound around the obtained compact with 18 turns on the primary side and 18 turns on the secondary side to obtain a test specimen. Next, iron loss was measured for the obtained test specimen. For the iron loss measurement, a BH analyzer SY-8218 manufactured by Iwasaki Communications Co., Ltd. was used. In addition, the measurement frequency for iron loss was set to 1 MHz, and the maximum magnetic flux density during iron loss measurement was set to 20 mT.

[0140] Next, for the insulator-coated soft magnetic powder of each sample No., iron loss [kW / m 3 was measured by the same method as described above. This measurement result is defined as "iron loss P2".

[0141] Next, the rate of reduction in iron loss due to the formation of the insulating film was calculated using the following formula. Rate of decrease in iron loss = (P1 - P2) / P1

[0142] Next, the calculated rate of reduction in iron loss was evaluated against the following evaluation criteria. The evaluation results are shown in Tables 3 to 5.

[0143] A: The rate of decrease in iron loss is less than 7%. B: The rate of decrease in iron loss is 7% or more but less than 10%. C: The rate of decrease in iron loss is 10% or more but less than 13%. D: The rate of decrease in iron loss is 13% or more.

[0144] 7.3. Coverage of the insulating coating Elemental mapping analysis was performed on the surface of each sample No. of the insulating soft magnetic powder using energy-dispersive X-ray spectroscopy (EDS). The coating performance of the insulating film was then evaluated by comparing the distribution of elements contained in the insulating film against the following evaluation criteria. The evaluation results are shown in Tables 3 to 5.

[0145] A: The insulating coating has particularly good coverage (the distribution of elements is particularly uniform). B: The insulating coating has moderately good coverage (there are slight inconsistencies in the distribution of elements). C: There are areas where the insulating coating does not provide sufficient coverage (there are variations within the acceptable range in the distribution of elements). D: The insulating coating has poor coverage (there is significant unevenness in the distribution of elements).

[0146] 7.4. Density of the molded body For each sample No. of the insulating coated soft magnetic powder, the density of the molded body was calculated using the following method.

[0147] First, epoxy resin equivalent to 2.0% by mass of the insulating soft magnetic powder is mixed with the insulating soft magnetic powder, and then the mixture is heated to 49.0 MPa (0.5 t / cm²). 2The material was compressed and molded under pressure. Next, the resulting molded body was heat-treated at 150°C for 30 minutes in an air atmosphere. This resulted in 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 volume and mass of the obtained molded body were measured. Meanwhile, the particle density of the insulating coated soft magnetic powder used was measured. A dry automatic densimeter capable of measurement by gas displacement was used to measure the particle density. Next, the density of the molded body was calculated from its volume and mass, and the relative density of the molded body was calculated from the obtained density and particle density of the molded body.

[0148] Next, the density of the molded body was evaluated by comparing the calculated relative density with the following evaluation criteria. The evaluation results are shown in Tables 3 to 5.

[0149] A: The molded body has a particularly high density (resulting in particularly good magnetic properties). B: The density of the molded body is slightly high (resulting in necessary and sufficient magnetic properties). C: The density of the molded body is slightly low, but within acceptable limits (the required magnetic properties are obtained). D: The density of the molded body is low (the required magnetic properties cannot be obtained).

[0150] 7.5. Overall Rating Each insulating soft magnetic powder was comprehensively evaluated by further applying the above evaluation results to the following evaluation criteria. The evaluation results are shown in Tables 3 to 5.

[0151] A: None of the above four evaluation results include a C or lower, and there is one or fewer Bs. B: None of the above four evaluation results are C or lower, and there are two or more B's. C: None of the above four evaluation results include D, and one or more include C. D: The above four evaluation results include D.

[0152] As shown in Tables 3 to 5, the insulating coated soft magnetic powders of each example exhibited good dielectric strength, a reduction in iron loss due to the formation of the insulating film, good coating properties of the insulating film, and good density of the molded body. This result is thought to be due to the good inter-particle insulation, good coating properties of the insulating film with minimal peeling (good adhesion), and suppressed film thickness in the insulating coated soft magnetic powders of each example. [Explanation of symbols]

[0153] 1...Insulating coated soft magnetic powder, 2...Soft magnetic powder, 3...Insulating coating, 10...Coil component, 11...Powdered magnetic core, 12...Conducting wire, 20...Coil component, 21...Powdered magnetic core, 22...Conducting wire, 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...Earpiece, 1300...Digital still camera, 1302...Case, 1304...Light receiving unit, 1306...Shutter button, 1308...Memory

Claims

1. A soft magnetic powder composed of an amorphous alloy soft magnetic material of the Fe-Si-B-C system, The surface of the soft magnetic powder is coated with an insulating film containing phosphate-based glass, It has, The average particle diameter is 15.0 μm or more and 40.0 μm or less. The aforementioned phosphoric acid-based glass is a glass whose main component is phosphorus oxide and which contains Li. An insulating coated soft magnetic powder characterized in that the ratio of Li content to P content, Li / P, determined by elemental analysis, is 0.01 or more and 0.20 or less.

2. The aforementioned phosphate-based glass further contains Zn, The insulating coated soft magnetic powder according to claim 1, wherein the ratio of Li content to Zn content, Li / Zn, determined by elemental analysis, is 0.03 or more and 0.30 or less.

3. The aforementioned phosphate-based glass further contains Na, The insulating coated soft magnetic powder according to claim 1, wherein the ratio of Li content to Na content, Li / Na, determined by elemental analysis, is 0.05 or more and 0.60 or less.

4. A weighed 0.7 g was used as the test sample. When the subject is placed inside a cylinder with an inner diameter of 8 mm and an axis in the vertical direction, and a load of 20 [kgf] (196 [N]) is applied to the subject by sandwiching it between electrodes from above and below, the withstand voltage is measured. The insulating coated soft magnetic powder according to claim 1, wherein the withstand voltage is 250 [V] or more and 700 [V] or less.

5. The insulating coated soft magnetic powder according to claim 1, wherein the volume fraction of the insulating coating is 0.30 volume% or more and 4.00 volume% or less.

6. A compacted magnetic core characterized by containing the insulating coated soft magnetic powder described in claim 1.

7. A magnetic element characterized by comprising a compacted magnetic core as described in claim 6.

8. An electronic device characterized by comprising the magnetic element described in claim 7.

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