Magnetic material

Abstract

The present disclosure provides a magnetic material comprising a plurality of metal magnetic particles and an insulating layer that covers each of the plurality of metal magnetic particles. In a cross-sectional view, when any one of the metal magnetic particles among the plurality of metal magnetic particles is defined as a first metal magnetic particle, the metal magnetic particle closest to the first metal magnetic particle, among the metal magnetic particles adjacent to the first metal magnetic particle, is defined as a second metal magnetic particle, and the equivalent circle diameter of the first metal magnetic particle is defined as d, and the shortest distance between the surface of the first metal magnetic particle and the surface of the second metal magnetic particle is defined as 2δ, the standard deviation of the δ / d value is greater than 0 and equal to or less than 0.092, and the average value of the δ / d value is 0.001-0.085.

Description

magnetic material

[0001] The present disclosure relates to magnetic materials.

[0002] As a magnetic material for electronic components such as coil components, a magnetic material having particles containing soft magnetic powder or the like composed of powder particles and a non-magnetic coating that covers the particles is sometimes used (see Patent Document 1).

[0003] JP 2016-162764 A

[0004] For example, the magnetic material described in Patent Document 1 includes particles with a particle size distribution having two peaks. The particles with the smaller particle size peak are either not coated with a non-magnetic coating or are coated with a thinner non-magnetic coating than the particles with the larger particle size peak. This improves the particle packing rate in the magnetic material and the initial magnetic permeability of the composite magnetic material.

[0005] However, in such a magnetic material, the magnetic flux density flowing through the particles with a large particle size is high, while the magnetic flux density flowing through the particles with a small particle size is low. The inventors have found that such a difference in magnetic flux density can reduce the uniformity of the magnetic flux density distribution in the magnetic material and degrade the DC bias characteristics.

[0006] The present disclosure has been made in view of the above-mentioned problems. That is, a main object of the present disclosure is to provide a magnetic material that is favorable in terms of initial permeability and DC bias characteristics.

[0007] The present inventors have conducted extensive research to solve the above problems, and as a result have invented a magnetic material that achieves the above-mentioned main object.

[0008] A magnetic material according to one embodiment of the present disclosure comprises a plurality of metal magnetic particles and an insulating layer covering each of the plurality of metal magnetic particles, wherein, in a cross-sectional view, any one of the plurality of metal magnetic particles is designated as a first metal magnetic particle, and among the metal magnetic particles adjacent to the first metal magnetic particle, the metal magnetic particle closest to the first metal magnetic particle is designated as a second metal magnetic particle, and when the circle-equivalent diameter of the first metal magnetic particle is designated as d and the shortest distance between the surface of the first metal magnetic particle and the surface of the second metal magnetic particle is designated as 2δ, the standard deviation of the δ / d value is greater than 0 and not greater than 0.092, and the average value of the δ / d value is 0.001 or greater and 0.085 or less.

[0009] According to one embodiment of the present disclosure, a magnetic material is provided that is suitable in terms of initial permeability and DC bias characteristics.

[0010] FIG. 1 is a schematic cross-sectional view of a magnetic material according to an embodiment of the present disclosure. FIG. 2 is a schematic enlarged cross-sectional view of portion I in FIG. 1. FIG. 3 is a schematic enlarged cross-sectional view of portion Ia in FIG. 2. FIG. 4 is a schematic cross-sectional view of a magnetic material according to an embodiment of the present disclosure. FIG. 5 is a schematic enlarged cross-sectional view of portion II in FIG. 4. FIG. 6 is a schematic cross-sectional view of a molded body according to an embodiment of the present disclosure. FIG. 7 is a schematic cross-sectional view of a molded body according to an embodiment of the present disclosure. FIG. 8 is a schematic internal see-through perspective view of an electronic component according to an embodiment of the present disclosure. FIG. 9 is a schematic front view of an electronic component according to an embodiment of the present disclosure.

[0011] The following describes specific embodiments of the present disclosure. The applicant provides the following description and examples to enable those skilled in the art to fully understand the present disclosure, and it should be noted that these are not intended to limit the subject matter described in the claims. In other words, the present disclosure is not particularly limited to the preferred embodiments described below, and can be implemented with appropriate modifications within the scope of its purpose. For convenience, the present disclosure may be divided into embodiments and examples to facilitate explanation or understanding of the key points. However, partial substitution and / or combination of the configurations shown in different embodiments is possible. In describing such embodiments, redundant explanations of substantially identical features may be omitted, and only differences may be described. In particular, similar effects resulting from similar configurations may not be mentioned in each embodiment.

[0012] The various numerical ranges referred to herein are intended to include the lower and upper numerical limits themselves unless otherwise specified, and the term "about" means that there may be a variation or difference of a few percent, for example, ±10%.

[0013] Hereinafter, a magnetic material according to an embodiment of the present disclosure will be described with reference to the drawings. Although the description will be made with reference to the drawings as necessary, the contents shown in the drawings are merely shown as schematic examples for the purpose of understanding the present disclosure, and the appearance, dimensional ratios, etc. may differ from the actual product.

[0014] 1 is a partial cross-sectional view schematically showing a magnetic material according to an embodiment of the present disclosure. As shown in the figure, the magnetic material 1 comprises a plurality of metal magnetic particles 10 and an insulating layer 20 covering the surface 12 of each of the metal magnetic particles 10. The magnetic material 1 can also be understood as comprising a plurality of composite particles 30 comprising the metal magnetic particles 10 and the insulating layer 20.

[0015] The metal magnetic particles 10 are metal magnetic particles having a particulate shape. In this specification, the "particulate" shape is not limited to a spherical shape, but also includes flat or amorphous shapes. For example, "particulate" includes those having various cross-sectional shapes such as circular, approximately elliptical, polygonal, and / or amorphous.

[0016] The metal magnetic particle 10 has a structure in which its outer surface 12 is covered with an insulating layer 20, and can also be referred to as the core of the composite particle 30. The material of the metal magnetic particle 10 is not particularly limited, but may be a soft magnetic material. When emphasis is placed on improving the initial magnetic permeability, it is particularly preferable that the material of the metal magnetic particle be a soft magnetic material containing iron. By using a soft magnetic material as the metal magnetic particle 10, a magnetic material with high magnetic flux density and high initial magnetic permeability can be obtained.

[0017] The soft magnetic material containing iron may contain various metal elements in addition to iron. While merely illustrative, the soft magnetic material may be iron or an iron alloy. The iron may be iron itself or an iron derivative, such as a complex. Examples of such iron derivatives include, but are not limited to, carbonyl iron, a complex of iron and CO, preferably pentacarbonyl iron. Particularly preferred is hard-grade carbonyl iron with an onion-skin structure (a structure in which concentric spherical layers are formed from the center of the particle) (e.g., hard-grade carbonyl iron manufactured by BASF). Examples of iron alloys include Fe—Si alloys, Fe—Al alloys, Fe—Ni alloys, Fe—Co alloys, Fe—Si—Al alloys, and Fe—Si—Cr alloys. The above alloys may further contain boron and / or carbon as other minor components. The content of the minor components is not particularly limited, but may be, for example, 0.1% by mass to 5.0% by mass, preferably 0.5% by mass to 3.0% by mass. The metal magnetic particles 10 may contain only one type of the metal magnetic material, or two or more types.

[0018] When prioritizing the high efficiency of electronic components to which the magnetic material is applied, it is more preferable that the metal magnetic particles 10 contain at least iron and nickel. By containing iron and nickel, a soft magnetic material with low coercivity can be obtained. By using a soft magnetic material with low coercivity as the metal magnetic particles 10, it is possible to reduce the magnetic core loss (core loss) of the magnetic material. This can enable the high efficiency of electronic components to which the magnetic material is applied.

[0019] In a soft magnetic material containing at least iron and nickel, the iron content can be 20 atomic % or more and 90 atomic % or less. When emphasizing obtaining a magnetic material with better initial permeability and DC bias characteristics, the iron content in the soft magnetic material containing iron and nickel is preferably 35 atomic % or more and 70 atomic % or less, more preferably 35 atomic % or more and 65 atomic % or less, even more preferably 45 atomic % or more and 65 atomic % or less, and particularly preferably 50 atomic % or more and 65 atomic % or less. By keeping the iron content within the above range, a magnetic material exhibiting a good balance of a good saturation magnetic flux density and initial permeability can be obtained. This allows for the provision of a magnetic material that favorably combines high initial permeability and excellent DC bias characteristics.

[0020] The insulating layer 20 covers the outer surface 12 of the metal magnetic particle 10. Therefore, the insulating layer 20 can also be referred to as a shell that covers the metal magnetic particle 10. The insulating layer 20 is composed of a material with high electrical resistivity. The insulating layer 20 can be one or more insulating coatings selected from the group consisting of inorganic glass coatings, organic-inorganic hybrid coatings, and inorganic insulating coatings formed by the sol-gel reaction of metal alkoxides. For example, the insulating layer 20 can be an oxide coating of the metal that constitutes the metal magnetic particle 10, i.e., a coating other than a self-generated oxide film. Note that the insulating layer 20 does not prevent the metal magnetic particle from having a self-generated oxide film. For example, the insulating layer 20 can have an electrical resistivity of 1×10 Ω·cm or more and 1×10 Ω·cm or less. The insulating layer 20 can also be composed of a non-magnetic material. Therefore, the insulating layer 20 can also be referred to as a high-resistance coating, insulating coating, or non-magnetic coating.

[0021] The insulating layer 20 can function as a high-resistance portion having a higher electrical resistivity than the metal magnetic particle 10. When emphasizing the importance of obtaining this function favorably, the insulating layer 20 preferably covers 90% or more of the surface perimeter of the metal magnetic particle 10 in a cross-sectional view, and more preferably covers the entire surface perimeter (100%). In a cross-sectional view, the insulating layer 20 may be formed continuously or intermittently. In other words, the outer surface of the metal magnetic particle 10 does not necessarily have to be covered entirely by the insulating layer 20. There may be regions on the outer surface of the metal magnetic particle 10 where the insulating layer 20 is not formed.

[0022] In the magnetic material 1, an insulating layer 20 and / or a gap may be interposed between adjacent metal magnetic particles 10. In other words, multiple metal magnetic particles 10 may be adjacent to each other via an insulating layer 20 and / or a gap. Multiple adjacent metal magnetic particles 10 may be separated by a predetermined distance by the insulating layer 20 and / or a gap. Additionally or alternatively, various additives such as resins, binders, and / or solvents may be present between the multiple metal magnetic particles. Such a structure insulates the metal magnetic particles from each other, thereby increasing the resistivity of the magnetic material 1 and suppressing an increase in eddy current loss. A magnetic material 1 in which an increase in eddy current loss is suppressed in this way may be particularly useful for use in high frequency ranges.

[0023] 1 , the magnetic material 1 includes a plurality of composite particles 30. The plurality of composite particles 30 may be arranged adjacent to one another in the magnetic material 1. The present inventors have newly discovered that a magnetic material 1 having excellent DC bias characteristics can be obtained by setting the distance between adjacent composite particles 30 to a value within a predetermined range according to the circle-equivalent diameter of the metal magnetic particles 10.

[0024] FIG. 2 is an enlarged cross-sectional view of portion I shown in FIG. 1. FIG. 3 is an enlarged cross-sectional view of portion Ia shown in FIG. 2. As shown in the figure, any composite particle 30 is adjacent to one or more composite particles. This structure can be interpreted as a structure in which any metal magnetic particle 10A is adjacent to one or more metal magnetic particles 10B. Hereinafter, for convenience of explanation, any metal magnetic particle 10A will be referred to as a first metal magnetic particle 10A. Furthermore, of the one or more metal magnetic particles adjacent to the first metal magnetic particle 10A, the metal magnetic particle 10B closest to the first metal magnetic particle 10A will be referred to as a second metal magnetic particle 10B.

[0025] In this specification, "closest metal magnetic particle" means the metal magnetic particle adjacent to the first metal magnetic particle 10A that has the shortest shortest distance from the surface 12A of the first metal magnetic particle to the surface of the adjacent metal magnetic particle.

[0026] In the magnetic material 1 of the present disclosure, when the circle-equivalent diameter of the first metal magnetic particle 10A in a cross-sectional view is d and the shortest distance between the surface 12A of the first metal magnetic particle 10A and the surface 12B of the second metal magnetic particle 10B (hereinafter simply referred to as the "interparticle distance" or "interparticle spacing") is 2δ, the standard deviation of the δ / d values ​​obtained for multiple first metal magnetic particles 10A may be greater than 0 and not greater than 0.092, and is more preferably greater than 0 and not greater than 0.05. As used herein, "standard deviation" is an index that indicates the variation in data, and a smaller standard deviation value means smaller variation.

[0027] The metal magnetic particles contained in the magnetic material 1 may have a particle size distribution. When the metal magnetic particles have a particle size distribution, the particle size of the metal magnetic particles is not constant and there is variation among the metal magnetic particles. Furthermore, as mentioned above, adjacent metal magnetic particles are separated by the presence of an insulating layer 20 or voids. The magnetic flux density flowing through a metal magnetic particle decreases as the distance between the metal magnetic particle and another adjacent metal magnetic particle increases relative to the particle size of the metal magnetic particle. Therefore, in a structure containing metal magnetic particles of different particle sizes, if the spacing between the metal magnetic particles is constant, the magnetic flux density flowing through the metal magnetic particle when a magnetic field is applied increases with increasing particle size of the metal magnetic particle and decreases with decreasing particle size. This results in an uneven magnetic flux density distribution in the magnetic material 1, which can result in a deterioration of the DC superposition characteristics of the magnetic material 1.

[0028] The magnetic material 1 according to an embodiment of the present disclosure has a standard deviation of the δ / d value within the above-mentioned range. Therefore, the magnetic material 1 can have a substantially uniform δ / d value for each of the plurality of first metal magnetic particles 10A. In other words, the ratio of the shortest distance 2δ between the first metal magnetic particle 10A and the second metal magnetic particle 10B to the size of the circle-equivalent diameter d of the first metal magnetic particle 10A is uniform for the plurality of first metal magnetic particles 10A included in the magnetic material 1. This means that the plurality of metal magnetic particles are arranged in the magnetic material 1 so that the shortest distance 2δ between adjacent metal magnetic particles is a value proportional to the circle-equivalent diameter d of the metal magnetic particle.

[0029] In short, in the magnetic material 1 of the present disclosure, the multiple metal magnetic particles are spaced apart by a distance 2δ corresponding to the circle-equivalent diameter d of the metal magnetic particles. Specifically, the shortest distance 2δ between metal magnetic particles 10 with a large circle-equivalent diameter d is large, while the shortest distance 2δ between metal magnetic particles 10 with a small circle-equivalent diameter d is small. This allows the magnetic flux density flowing through each of the multiple metal magnetic particles with different circle-equivalent diameters to be uniform in the magnetic material 1 including multiple metal magnetic particles 10 with a particle size distribution. As a result, the magnetic flux density distribution in the magnetic material 1 is uniform, thereby improving the DC superposition characteristics of the magnetic material 1.

[0030] The average value of the δ / d value may be 0.001 or more and 0.087 or less, more preferably 0.001 or more and 0.085 or less, and even more preferably 0.003 or more and 0.079 or less. When the average value of the δ / d value is in the above-mentioned range, a magnetic material 1 having a good balance between a suitable initial magnetic permeability and high-frequency characteristics can be provided.

[0031] Specifically, when the average value of the δ / d value is greater than the upper limit mentioned above, i.e., when the shortest distance 2δ between adjacent metal magnetic particles is excessively large relative to the circle-equivalent diameter d of the metal magnetic particles, the filling rate of the metal magnetic particles 10 contained in the magnetic material 1 decreases. This reduces the initial permeability of the magnetic material 1. Furthermore, when the average value of the δ / d value is less than the lower limit mentioned above, i.e., when the shortest distance 2δ between adjacent metal magnetic particles is excessively small relative to the circle-equivalent diameter d of the metal magnetic particles, the insulation between adjacent metal magnetic particles decreases. This reduces the resistivity of the magnetic material 1 and increases eddy current loss. By keeping the average value of the δ / d value within the above range, a magnetic material 1 can be provided that has a good balance between favorable initial permeability and favorable high-frequency characteristics.

[0032] (Measurement of Equivalent Circle Diameter) The equivalent circle diameter d is obtained by analyzing a cross-sectional image of the magnetic material 1 using image processing software. An exemplary measurement procedure is as follows: (1) After embedding the magnetic material in resin, it is cut at an arbitrary location and the cut cross section is polished. Polishing may be performed, for example, using a focused ion beam (FIB) device (e.g., a JEOL FIB device). (2) For the polished cross section, a scanning transmission electron microscope (STEM-EDX) (e.g., a JEOL STEM device) is used to capture images of at least one entire metal magnetic particle from 10 or more fields of view. The image resolution may be 10 nm / pixel or more, and the field of view may be, for example, 20 μm × 20 μm. (3) For each metal magnetic particle whose entirety is captured in the captured image, the equivalent circle diameter (Heywood diameter: diameter equivalent to a circle with an equal area) is measured. For the measurement, image processing software such as Winroof (manufactured by Mitani Corporation) may be used. The circle-equivalent diameter is determined for each of 100 or more metal magnetic particles, and the average value is calculated.

[0033] (Measurement of Interparticle Distance) The interparticle distance 2δ, like the circle-equivalent diameter d, can be obtained by analyzing a cross-sectional image of the magnetic material 1 using image processing software. An exemplary measurement procedure is as follows: (1) After embedding the magnetic material in resin, it is cut at an arbitrary location and the cut cross-section is polished using an FIB device or the like. (2) For the polished cross-section, images are taken of 10 or more fields of view using STEM-EDX, capturing the entirety of at least one metal magnetic particle and at least a portion of the metal magnetic particle adjacent to that metal magnetic particle. The image resolution is 1 nm / pixel or more, and the field of view area may be, for example, 0.3 μm × 0.3 μm. (3) For each metal magnetic particle whose entirety is captured in the captured image, the shortest distance between that metal magnetic particle and the metal magnetic particle nearest to that metal magnetic particle is measured. Image processing software such as Winroof (manufactured by Mitani Corporation) may be used for the measurement. The interparticle distance 2δ is determined for each of 50 or more metal magnetic particles, and the average value is calculated.

[0034] (Measurement of δ / d Value) The δ / d value can be calculated by analyzing a cross-sectional image of the magnetic material 1 taken in the same manner as in measuring the interparticle distance using image processing software. Specifically, for each metal magnetic particle whose entirety is captured in the cross-sectional image, the circle-equivalent diameter d and the shortest distance 2δ between the metal magnetic particle and the metal magnetic particle nearest to that metal magnetic particle are measured. The δ / d value is calculated from the obtained circle-equivalent diameter d and shortest distance 2δ. The δ / d value is calculated for each of 50 or more metal magnetic particles, and the average value and standard deviation are determined.

[0035] The first metal magnetic particle 10A and the second metal magnetic particle 10B may be adjacent to each other and spaced apart via an insulating layer 20. For example, a first insulating layer 20A covering the first metal magnetic particle 10A and / or a second insulating layer 20B covering the second metal magnetic particle 10B may be present between the first metal magnetic particle 10A and the second metal magnetic particle 10B. The first insulating layer 20A and the second insulating layer 20B may be in close contact with each other. Preferably, the first insulating layer 20A and the second insulating layer 20B may be bonded to each other between the first metal magnetic particle 10A and the second metal magnetic particle 10B.

[0036] "Bonding" of the insulating layer refers to a structure in which an insulating layer is continuously formed to cover each of a plurality of adjacent metal magnetic particles. In such a structure, there does not need to be a clearly visible boundary between the first insulating layer 20A and the second insulating layer 20B. That is, each of a plurality of adjacent metal magnetic particles may be covered by a single continuous insulating layer. A plurality of adjacent metal magnetic particles (e.g., the first metal magnetic particle 10A and the second metal magnetic particle 10B) may share a single insulating layer. Such a structure can also be interpreted as a structure in which the first insulating layer 20A and the second insulating layer 20B are "connected" or "integrated."

[0037] In a structure in which the first insulating layer 20A and the second insulating layer 20B are closely or bonded, the shortest distance 2δ between the first metal magnetic particles 10A and the second metal magnetic particles 10B corresponds to the sum of the thickness of the first insulating layer 20A and the thickness of the second insulating layer 20B. Therefore, the standard deviation of the δ / d value being within a predetermined range means that the insulating layer 20 has a thickness corresponding to the circle-equivalent diameter d of the metal magnetic particles 10, and the variation in this ratio is kept below a predetermined value. This ensures insulation between the metal magnetic particles while homogenizing the magnetic flux density distribution in the magnetic material 1, resulting in a magnetic material 1 with excellent DC bias characteristics. Furthermore, by arranging the first insulating layer 20A and the second insulating layer 20B in contact with each other or being bonded, the filling rate of the composite particles 30 in the magnetic material 1 can be improved, thereby improving the initial magnetic permeability.

[0038] Furthermore, the average value Δ of the interparticle distances 2δ among the multiple first metal magnetic particles 10A can be 0.006 μm or more and 0.5 μm or less. When prioritizing suppressing the increase in eddy current loss of the magnetic material and improving permeability, the average value Δ of the interparticle distances 2δ is preferably 0.006 μm or more and 0.18 μm or less. By having the average value Δ be equal to or less than the above-mentioned upper limit value, the filling rate of the metal magnetic particles 10 in the magnetic material 1 is improved, and a suitable initial permeability can be achieved. Furthermore, by having the average value Δ be equal to or more than the above-mentioned lower limit value, sufficient insulation is achieved between the metal magnetic particles, and an increase in eddy current loss is suppressed, thereby obtaining suitable high-frequency characteristics.

[0039] The average circularity of the plurality of first metal magnetic particles 10A can be 0.70 or more and 0.95 or less. When prioritizing the improvement of the initial magnetic permeability and DC bias characteristics of the magnetic material 1, the average circularity is more preferably 0.78 or more and 0.91 or less. When the average circularity is within the above range, the filling rate of the metal magnetic particles 10 in the magnetic material 1 is improved. Furthermore, it becomes possible for the composite particles 30 to be packed in contact with each other. This can provide a magnetic material that is superior in terms of initial magnetic permeability and DC bias characteristics.

[0040] (Measurement of Circularity) The circularity of the metal magnetic particles can be obtained by analyzing a cross-sectional image of the magnetic material 1 using image processing software, similar to the measurement of the circle-equivalent diameter d. An exemplary measurement procedure is as follows: (1) After embedding the magnetic material in resin, it is cut at an arbitrary location and the cut cross section is polished using an FIB device or the like. (2) The polished cross section is photographed using STEM-EDX to capture images of at least one entire metal magnetic particle from 10 or more fields of view. The image resolution is 10 nm / pixel or more, and the field of view area may be, for example, 20 μm × 20 μm. (3) The circularity of each of the metal magnetic particles whose entirety is photographed in the 10 photographed fields of view is analyzed. For example, image processing software such as Winroof (manufactured by Mitani Corporation) may be used for the analysis. The circularity of 100 or more metal magnetic particles is determined and the average value is calculated.

[0041] The average particle size of the metal magnetic particles 10 can be 0.01 μm or more and 300 μm or less. Considering the initial magnetic permeability and its frequency characteristics, the average particle size of the first metal magnetic particles 10A is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 8 μm or less, and even more preferably 1 μm or more and 5 μm or less. When the average particle size of the metal magnetic particles 10 is within the above range, this can be advantageous in terms of the initial magnetic permeability and its frequency characteristics. Furthermore, when the average particle size of the metal magnetic particles 10 is within the above range, the magnetic material 1 can exhibit high electrical resistance. This can increase the electrical resistance of the path of the eddy current flowing through the magnetic material 1, thereby reducing eddy current loss.

[0042] Furthermore, when the particle size distribution of the metal magnetic particles includes multiple peaks and the average particle size of the second metal magnetic particles 10B is smaller than that of the first metal magnetic particles 10A, if emphasis is placed on improving the filling rate of the composite particles 30, it is preferable that the average particle size of the second metal magnetic particles 10B be 0.1 μm or more and 1 μm or less.

[0043] In this specification, "average particle diameter" corresponds to D50. D50 means the particle diameter at the point where the cumulative value from the smallest particle side reaches 50% in a cumulative curve (particle size distribution) obtained by calculating the particle size distribution on a volume basis and setting the total volume to 100%. The particle diameter may be the circle-equivalent diameter of the metal magnetic particle in a cross-sectional view.

[0044] (Measurement of particle size distribution) The particle size distribution is obtained by calculating the equivalent circle diameter of each particle observed in the cross-sectional image according to the above-mentioned method for measuring the equivalent circle diameter, counting the frequency of metal magnetic particles (particle frequency) for each equivalent circle diameter interval, and graphing the correlation between the equivalent circle diameter and particle frequency on a volume basis.

[0045] Furthermore, in the particle size distribution of the first metal magnetic particles 10A contained in the magnetic material 1, if the particle size at the point where the cumulative value from the small particle side is 90% is defined as D90 and the particle size at the point where the cumulative value is 10% is defined as D10, the value of D90 / D10 is preferably 1 or more and 5.5 or less, more preferably 1 or more and 3.1 or less. The value of D90 / D10 being within the above range means that there are almost no metal magnetic particles 10 having a particle size (equivalent circle diameter d) that is excessively large compared to the average particle size (D50). As described above, in the magnetic material 1 of the present disclosure, the distance 2δ between the first metal magnetic particles 10A and the second metal magnetic particles 10B is proportional to the equivalent circle diameter d of the first metal magnetic particles 10A. Therefore, the larger the equivalent circle diameter d of the metal magnetic particles, the larger the interparticle distance 2δ. When the value of D90 / D10 is within the above-mentioned range, there are almost no first metal magnetic particles with an excessively large interparticle distance 2δ, so the filling rate of the metal magnetic particles 10 in the magnetic material 1 is improved, and a magnetic material 1 with high initial magnetic permeability can be obtained.

[0046] Furthermore, when the D90 / D10 value is within the above-mentioned range, the particle size distribution width of the first metal magnetic particles 10A becomes sharper. This means that the circle-equivalent diameter d of the first metal magnetic particles 10A is more uniform. Therefore, by forming insulating layers 20 of the same thickness on multiple metal magnetic particles 10 and packing the insulating layers 20 closely together in the magnetic material 1 so that they are in contact with each other, the standard deviation of the δ / d value can be made closer to 0. This makes it possible to obtain a magnetic material 1 having a more uniform magnetic flux density distribution and excellent DC bias characteristics.

[0047] The metal magnetic particles 10 contained in the magnetic material 1 may have a particle size distribution with a single peak. Alternatively, the metal magnetic particles 10 may have a particle size distribution with two peaks. That is, the metal magnetic particles 10 contained in the magnetic material 1 may include large-sized metal magnetic particles (hereinafter also referred to as "large particles") with a relatively large average particle size and small-sized metal magnetic particles (hereinafter also referred to as "small particles") with a relatively small average particle size (see FIG. 4 or FIG. 5). By including two types of metal magnetic particles with different average particle sizes, the filling rate of the metal magnetic particles in the magnetic material 1 can be further increased. This can provide a magnetic material 1 with high initial magnetic permeability.

[0048] The number of peaks in the particle size distribution is not limited to two, and may be three or more. When the particle size distribution includes three or more peaks, the metal magnetic particles whose average particle size is the particle size corresponding to the smallest peak are defined as small-diameter metal magnetic particles. The metal magnetic particles whose average particle size is the particle size corresponding to the largest peak are defined as large-diameter metal magnetic particles.

[0049] The average particle size of the first metal magnetic particles 10A and the average particle size of the second metal magnetic particles 10B may be different from each other. For example, the first metal magnetic particles 10A may be large-sized magnetic particles, and the second metal magnetic particles 10B may be small-sized metal magnetic particles. Alternatively, the first metal magnetic particles 10A may be small-sized magnetic particles, and the second metal magnetic particles 10B may be large-sized metal magnetic particles.

[0050] When the metal magnetic particles have a particle size distribution including multiple peaks, the average circularity of the large-diameter metal magnetic particles having a large average particle size can be 0.70 or more and 0.95 or less. When prioritizing the improvement of the initial magnetic permeability and DC bias characteristics of the magnetic material, the average circularity is more preferably 0.78 or more and 0.91 or less. When the average circularity is within the above range, the filling rate of the metal magnetic particles in the magnetic material 1 is improved. Furthermore, the composite particles can be packed in contact with each other. This can provide a magnetic material with better initial magnetic permeability and DC bias characteristics.

[0051] Furthermore, when prioritizing the initial magnetic permeability and its frequency characteristics, the average particle size of the large-diameter metal magnetic particles is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 8 μm or less, and even more preferably 1 μm or more and 5 μm or less. When prioritizing the improvement of the filling rate of the composite particles, the average particle size of the small-diameter metal magnetic particles is preferably 0.1 μm or more and 1 μm or less.

[0052] Furthermore, in the particle size distribution of large-sized metal magnetic particles, if the particle size at which the cumulative value from the small particle side reaches 90% is defined as D90 and the particle size at which the cumulative value reaches 10% is defined as D10, the value of D90 / D10 is preferably 1 or more and 5.5 or less, and more preferably 1 or more and 3.1 or less. When the value of D90 / D10 is within the above range, there are no large-sized metal magnetic particles with an excessively large interparticle distance 2δ, so the filling rate of the metal magnetic particles in the magnetic material is improved, and a magnetic material with high initial magnetic permeability can be obtained.

[0053] (Measurement of D90 and D10) The D90 and D10 values ​​of large-sized metal magnetic particles can be determined as follows. (1) The particle size distribution is obtained according to the method described above in (Measurement of particle size distribution). (2) Assuming that the large-sized metal magnetic particles and the small-sized metal magnetic particles are each logarithmically distributed, the frequency in the particle size distribution obtained in (1) is converted to a logarithm. A Gaussian function, a Voigt function, or a Lorentz function is applied to each peak in the logarithmic particle size distribution for fitting, and each particle size distribution is separated. (3) In each of the separated particle size distribution peaks, the particle size distribution containing the largest particle diameter is determined to be the particle size distribution of large-sized metal magnetic particles, and D90 and D10 are obtained from this particle size distribution.

[0054] When emphasizing the high efficiency of electronic components to which the magnetic material is applied, it is more preferable that the large-sized metal magnetic particles contain at least iron and nickel. The iron content in the large-sized metal magnetic particles containing iron and nickel is preferably 35 atomic % or more and 65 atomic % or less, more preferably 45 atomic % or more and 65 atomic % or less, and particularly preferably 50 atomic % or more and 65 atomic % or less. By having the iron content within the above range, a magnetic material can be obtained that exhibits a good balance of a suitable saturation magnetic flux density and initial magnetic permeability. This makes it possible to provide a magnetic material that favorably combines high initial magnetic permeability and excellent DC bias characteristics.

[0055] Furthermore, the magnetic material 1 of the present disclosure may be in the form of a molded body obtained by compressing and molding the magnetic material 1. Such a molded body can also be called, for example, a compression molded body or a pressure molded body.

[0056] The compact can be obtained, for example, by pressure molding a mixture of the magnetic material 1 of the present disclosure and a resin. The compact may contain various additives such as a resin, a binder, a solvent, and / or a curing agent. These additives may be present, for example, between adjacent composite particles 30.

[0057] The molded article can be used in various electronic components including coil components, etc. By way of example only, the molded article can be used in magnetic cores, element bodies for electronic components having coil conductors inside, etc.

[0058] The coil conductor is made of a conductive material, and may be at least one selected from the group consisting of silver, copper, and aluminum. The shape of the coil conductor is not particularly limited and may be various shapes, such as a wound shape or a meandering shape. For example, the coil conductor may be made of a conductive paste or a wire.

[0059] Fig. 6 is a schematic cross-sectional view of a compact 2 in which the particle size distribution of the metal magnetic particles 10 has a single peak. Fig. 7 is a schematic cross-sectional view of a compact 2A in which the particle size distribution of the metal magnetic particles 10 has two peaks. As shown in the figure, the composite particles 30 contained in the magnetic material 1 are plastically deformed by pressure, and multiple composite particles 30 can be arranged more closely together. This improves the packing rate of the composite particles 30, and a compact with high initial magnetic permeability can be provided.

[0060] The compact of the present disclosure has similar features to those described for the magnetic material 1 described above. To avoid repetition, specific descriptions related to the same features as those for the magnetic material 1 will be omitted. For example, the surfaces of the metal magnetic particles 10 included in the compact 2 may be separated from adjacent metal magnetic particles by being covered with an insulating layer 20. Additionally or alternatively, adjacent metal magnetic particles may be separated from each other by gaps present between the metal magnetic particles. In such a structure, the interparticle distance 2δ between the first metal magnetic particle 10A, which is an arbitrary metal magnetic particle, and the second metal magnetic particle 10B located closest to the first metal magnetic particle 10A may be a value corresponding to the circle-equivalent diameter d of the first metal magnetic particle 10A, as in the magnetic material 1 described above.

[0061] [Method of manufacturing magnetic material] Next, a method of manufacturing a magnetic material according to an embodiment of the present disclosure will be described. Note that the method described below is merely an example, and the method of manufacturing a magnetic material according to this embodiment is not limited to the following method.

[0062] The metal magnetic particles are made of a metal magnetic material having a desired particle size. The particles may have a particle size distribution with a single peak, or may have a particle size distribution with multiple peaks. When prioritizing the improvement of the packing density and magnetic properties of the magnetic material 1, the circularity of the particles is preferably 0.70 to 0.95, more preferably 0.80 to 0.95, and even more preferably 0.90 to 0.95. Commercially available particles of such metal magnetic material may be used. Alternatively, particles obtained by atomization or liquid-phase synthesis may be used.

[0063] Next, an insulating layer is formed on the surface of the metal magnetic particles. The insulating layer may be formed, for example, using a sol-gel method. In this case, the metal magnetic particles are shaken using a sieve shaker (AS200, manufactured by Retsch, mesh size: 1 μm or more and 20 μm or less) to classify the metal magnetic particles into fine levels (e.g., particle size intervals of 1 μm) according to a predetermined particle size, and an insulating layer having a thickness proportional to the average particle size (D50) at each level may be formed for each of the classified metal magnetic particles. The thickness of the insulating layer may be controlled, for example, by adjusting the time of the sol-gel reaction or the amount of material added used in the sol-gel reaction.

[0064] [Electronic Components] Next, electronic components using the magnetic material according to the present disclosure will be described below.

[0065] 8 is a perspective view schematically illustrating an exemplary laminated coil component as an inductor using the magnetic material according to the present disclosure. The inductor 100 includes an element body 110 containing the magnetic material 1 according to the present disclosure and a conductor pattern 120 embedded within the element body 110. Such an inductor 100 is obtained by alternately printing and stacking a paste containing the magnetic material according to the present disclosure for forming the element body 110 and a conductor paste (e.g., silver paste) for forming the coil conductor pattern 120, and then subjecting the laminate to heat treatment. This allows for the production of an inductor 100 in which the conductor pattern 120 is encapsulated within the element body 110. Although not shown, the outer surface of the inductor 100 may be covered with an insulating resin.

[0066] An external electrode 130 electrically connected to the conductor pattern 120 may be disposed on the outer surface of the inductor 100. The external electrode 130 may be formed by, for example, plating, applying a conductive paste to the element body and baking it, and / or sputtering. For example, the insulating resin covering the outer surface of the inductor may have a coating removed by a laser from the portion where the wiring and the external electrode are connected, followed by plating to form the external electrode 130.

[0067] The paste forming the element body 210 may contain, in addition to the composite particles 30, a resin, a binder, and a solvent. The resin may be at least one selected from the group consisting of thermosetting resins such as epoxy resin, phenolic resin, and silicone resin, and low-melting-point glass. The binder may be, for example, cellulose such as ethyl cellulose, or polyvinyl butyral. The solvent may be, for example, terpineol or butyl diglycol acetate.

[0068] 9 is a front view schematically illustrating an exemplary electronic component 200 that uses a magnetic material compact according to the present disclosure as a toroidal ring core. In the electronic component 200, a coil conductor 220 is wound around a base body 210, which is the compact.

[0069] The compact may be formed from a slurry obtained by mixing a particle raw material containing metal magnetic particles, a resin, and a solvent. Specifically, the particle raw material containing the resin and the solvent may be mixed until the solvent evaporates and the mixture becomes sandy.

[0070] The resin may be, for example, at least one selected from the group consisting of epoxy resin, phenol resin, polyester resin, polyimide resin, polyolefin resin, and silicone resin. In terms of electrical insulation and / or mechanical strength, the resin may be, for example, a thermoplastic epoxy resin.

[0071] The solvent may be an organic solvent used to mix the materials to obtain a slurry, such as an aromatic hydrocarbon such as toluene or xylene, a ketone such as acetone, methyl ethyl ketone, or methyl isobutyl ketone, an alcohol such as methanol, ethanol, or isopropyl alcohol, or a glycol ether such as propylene glycol monomethyl ether or propylene glycol monomethyl ether acetate.

[0072] The particle raw material may further contain various additives such as a curing agent for curing the resin.

[0073] The solvent may then be removed from the mixture by heating and drying it. The resulting dried mixture may be shaken in a sieve shaker (mesh size: 160 μm or more and 300 μm or less) to obtain a granulated powder. As used herein, "granulated powder" refers to a particulate material used to produce a compact.

[0074] Next, the produced granulated powder is filled into a mold. For example, the mold may be, but is not limited to, a mold for producing the ring-shaped toroidal ring core shown in this embodiment. For example, the mold may be a mold for producing at least one selected from the group consisting of an E-type core, an I-type core, a T-type core, and a plate-shaped core. The mold filled with the granulated powder may be introduced into a pressure molding machine and pressurized at room temperature (e.g., 20°C or higher and 40°C or lower). Here, if the granulated powder contains the above-mentioned thermosetting resin, the temperature during pressurization may be relatively low, such as 20°C or higher and 40°C or lower, so that the curing reaction does not proceed, and the resin may remain uncured or semi-cured. For example, if the resin is stored in an uncured or semi-cured state and it becomes necessary to produce a magnetic compact that is almost completely cured as a product, final pressure molding may be performed at the temperature required for curing. The pressure during pressure molding is not particularly limited, but may be, for example, 50 MPa or higher and 150 MPa or lower. Generally, the higher the pressure at which the compact is pressed, the easier it is for the composite particles contained in the compact to undergo plastic deformation, and the higher the packing density of the composite particles.

[0075] The obtained compact may be heat-treated (fired) in an air atmosphere at a predetermined temperature, for example, about 200°C or higher and 950°C or lower.

[0076] According to the present disclosure, in both molding by layer printing of paste and molding by pressure using a mold, by using the magnetic material 1 or molded body of the present disclosure containing composite particles having an insulating layer according to the particle size, the magnetic flux density distribution is made uniform, and it is possible to obtain electronic components with better DC superposition characteristics.

[0077] Although the embodiments of the present disclosure have been described above, they are merely typical examples. Those skilled in the art will readily understand that the present disclosure is not limited thereto, and that various modifications are possible without departing from the spirit and scope of the present invention.

[0078] Note that one embodiment of the present disclosure as described above includes the following preferred aspects: <1> A magnetic material comprising a plurality of metal magnetic particles and an insulating layer covering each of the plurality of metal magnetic particles, wherein, in a cross-sectional view, any of the plurality of metal magnetic particles is a first metal magnetic particle, and of the metal magnetic particles adjacent to the first metal magnetic particle, the metal magnetic particle closest to the first metal magnetic particle is a second metal magnetic particle, and where d is the equivalent-circle diameter of the first metal magnetic particle and 2δ is the shortest distance between the surface of the first metal magnetic particle and the surface of the second metal magnetic particle, the standard deviation of δ / d values ​​is greater than 0 and 0.092 or less, and the average value of δ / d values ​​is 0.001 or more and 0.085 or less. <2> The magnetic material according to <1>, wherein the plurality of metal magnetic particles are adjacent to each other via the insulating layer. <3> The magnetic material according to <1> or <2>, wherein a first insulating layer covering the first metal magnetic particles and a second insulating layer covering the second metal magnetic particles are bonded to each other. <4> The magnetic material according to <3>, wherein the shortest distance 2δ is the sum of the thickness of the first insulating layer and the thickness of the second insulating layer. <5> The magnetic material according to any one of <1> to <4>, wherein, in a cross-sectional view, the average value Δ of the shortest distances 2δ is 0.006 μm or more and 0.18 μm or less. <6> The magnetic material according to any one of <1> to <5>, wherein a particle size distribution curve of the plurality of metal magnetic particles has a single peak. <7> The magnetic material according to <6>, wherein, in a cumulative particle size distribution curve of the metal magnetic particles, the value of D90 / D10 is 1 or more and 5.5 or less, where D10 is the particle size at which the cumulative value from the fine particle side reaches 10% and D90 is the particle size at which the cumulative value reaches 90%. <8> The magnetic material according to <6> or <7>, wherein the metal magnetic particles have an average circularity of 0.78 to 0.91 in cross-sectional view. <9> The magnetic material according to any one of <6> to <8>, wherein in a cumulative particle size distribution curve of the metal magnetic particles, D50, which is the particle size at which the cumulative value from the fine particle side reaches 50%, is 0.1 μm to 10 μm. <10> The magnetic material according to any one of <6> to <9>, wherein the metal magnetic particles contain at least Fe and Ni, and the Fe content in the metal magnetic particles is 35 atomic % to 70 atomic %.<11> The magnetic material according to any one of <1> to <5>, wherein the plurality of metal magnetic particles include large particles with a large average particle size and small particles with a small average particle size. <12> The magnetic material according to <11>, wherein, in a cumulative particle size distribution curve of the large particles, the value of D90 / D10 is 1 or more and 5.5 or less, where D10 is the particle size at which the cumulative value from the fine particle side is 10% and D90 is the particle size at which the cumulative value from the fine particle side is 90%. <13> The magnetic material according to <11> or <12>, wherein, in a cross-sectional view, the average circularity of the large particles is 0.78 or more and 0.91 or less. <14> The magnetic material according to any one of <11> to <13>, wherein D50, which is the particle size at which the cumulative value from the fine particle side is 50% in a cumulative particle size distribution curve of the large particles, is 0.1 μm or more and 10 μm or less. <15> The magnetic material according to any one of <11> to <14>, wherein the large particles contain at least Fe and Ni, and the Fe content in the large particles is 35 atomic % or more and 65 atomic % or less. <16> An electronic component comprising: an element body including the magnetic material according to any one of <1> to <15>; and a coil conductor. <17> An electronic component comprising the magnetic material according to any one of <1> to <15>; and a coil wound around the magnetic material.

[0079] The above effects are merely exemplary, and the present disclosure is not limited to the above, and additional effects may also be achieved.

[0080] Examples related to the present disclosure will be described below. For each of the magnetic materials of the examples and comparative examples shown below, the magnetic property data and geometric parameters were evaluated using simulation.

[0081] [Simulation Method] <Simulation Conditions and Model> The simulation was performed using Femtet2022 (Murata Software). The solver was set to magnetic field analysis (static analysis), and the option was set to differential inductance. The model was two-dimensional. The standard mesh size for the analysis domain was set to 0.015 mm.

[0082] The B-H curve data for the examples and comparative examples were values ​​calculated from the following formula (I) or values ​​obtained from toroidal ring cores fabricated according to the procedure described below. Note that the B-H curve was calculated using the relative permeability μ ｒ The part where the value is 1 or more was used, and further extrapolated to the magnetic permeability of a vacuum using Femtet2022. The wiring material was copper. The creation of a cross-sectional model of the magnetic material used in the simulation will be described later.

[0083] <Acquisition of BH Curve Data Used in Simulation> The BH curve data for Examples 1 to 23 and Comparative Examples 1 to 4 were acquired by calculation from the above formula (I), as will be explained below.

[0084] (A) Examples 1 to 21 and Comparative Examples 1 to 4 In the model simulations of Examples 1 to 21 and Comparative Examples 1 to 4, the metal magnetic particles were Fe6.5Si alloy particles containing 93.5 wt% iron and 6.5 wt% silicon. A tanh curve approximating the B-H curve of the alloy particles was calculated from formula (I). The values ​​used for the calculation were μ ０ is the magnetic permeability of a vacuum (4π×10 －７ H (A / m), H (A / m) is the applied magnetic field, Bs (saturation magnetic flux density) is 1.6 T, and μ (magnetic permeability) is 7000 H / m.

[0085] (B) Examples 22 and 23 For Examples 22 and 23, simulations were carried out on magnetic materials containing two types of metal magnetic particles with different average particle sizes. For the large-diameter metal magnetic particles, the B-H curve data of Fe6.5Si used in the simulation of (A) was used. On the other hand, for the small-diameter metal magnetic particles, particles of pure Fe composition were used. A tanh curve approximating the B-H curve of the particles was calculated from formula (I). The values ​​used for the calculation were μ ０ is the magnetic permeability of a vacuum (4π×10 －７ H (A / m), H (A / m) is the applied magnetic field, Bs (saturation magnetic flux density) is 2.1 T, and μ (magnetic permeability) is 1000 H / m.

[0086] (C) Examples 24 to 33 In Examples 24 to 33, coil components were prepared by winding a coil conductor around an actually manufactured toroidal ring core, and μ-H curve data was obtained using the coil components.

[0087] To prepare the toroidal ring core, metal magnetic particles with an average particle size of 0.3 μm to 3.0 μm, resin, and solvent were placed in a mortar and mixed until the solvent evaporated to form a sandy mixture. The metal magnetic particles were alloy particles containing iron and nickel. Multiple toroidal ring cores were prepared using alloy particles containing various iron and nickel content ratios, and each toroidal ring core was evaluated. A thermoplastic epoxy resin was used as the resin. Methyl ethyl ketone (MEK) was used as the solvent. Table 3 shows only the iron content, with the remainder representing the Ni content.

[0088] The sandy material obtained by mixing was oven-dried at 50°C for 30 minutes to volatilize the solvent, and the resulting dried material was shaken in a sieve shaker (AS200, manufactured by Retsch, mesh size: 160 μm to 300 μm) to obtain granulated powder. The granulated powder was then pressure-molded at room temperature (approximately 25°C) under 120 MPa for 2 minutes to produce a toroidal ring core.

[0089] The toroidal ring core was degreased under a nitrogen atmosphere. ２ and 97% by volume of N ２ The mixture was sintered at 900° C. for 60 minutes in a reducing atmosphere containing the above-mentioned components, thereby obtaining a toroidal ring core as a sintered body.

[0090] A coil conductor (copper, φ0.5 mm) was wound around the obtained toroidal ring core, and the magnetic permeability μ with respect to the applied magnetic field H was measured at 100 Hz using a 4284A Precision LCR meter (manufactured by Keysight Technologies). The μ-H curve data obtained by the measurement was converted into B-H curve data, and the B-H curve data used in the simulation was calculated.

[0091] <Method of Creating a Cross-Sectional Model of a Magnetic Material Used in Simulation> First, particle size distribution data for any powder having a particle size distribution with an average particle size of 1 μm to 10 μm was prepared. Furthermore, for simulations of cross-sectional models of magnetic materials containing two types of metal magnetic particles with different average particle sizes (Examples 22 and 23), particle size distribution data for powder having a particle size distribution with an average particle size of 0.1 μm to 1 μm was used.

[0092] Next, in the prepared particle size distribution data, the particle size that matches the volume frequency of the metal magnetic particles of each particle size and is 150 μm ３ The number of metal magnetic particles of each particle size was calculated so that the total volume occupancy of each metal magnetic particle in the region was 70 to 75%. In Examples 22 and 23, the number of metal magnetic particles of each particle size was calculated so that the particle distribution ratio of two types of metal magnetic particles with different average particle sizes was an arbitrary value. The particle distribution ratio was set to a ratio that allowed the small-sized metal magnetic particles to enter the triple junctions of the large-sized metal magnetic particles, but prevented the small-sized metal magnetic particles from agglomerating. Then, ３ All the calculated metal magnetic particles were randomly packed into the region in order from the metal magnetic particle with the largest volume.

[0093] Finally, a cross section parallel to a certain face of the cube was cut out from the cubic region, and the resulting 2D cross-sectional image was output. In some examples and comparative examples, Winroof's image processing software was used to perform exclusive expansion processing an arbitrary number of times on all particles in the 2D cross-sectional image. Next, Winroof's image processing software or the like was used to shrink all particles in the 2D cross-sectional image by the thickness of an arbitrary insulating layer. Then, a coil (material: copper) was set on one end of the image, and a boundary condition (electric wall) was set on the other end, and this was used as a cross-sectional model of the magnetic core to be used in the simulation.

[0094] <Acquisition of geometric parameters of cross-sectional models (equivalent circle diameter d, interparticle distance δ, circularity)> The equivalent circle diameter d, interparticle distance 2δ, and circularity of the metal magnetic particles in the simulation models of the examples and comparative examples were obtained by analyzing the output 2D cross-sectional images using Winroof image processing software. The interparticle distance measurement function, which is a function of Winroof, was used to acquire the data.

[0095] <Acquisition of Magnetic Property Data of Model> In the simulation models of the examples and comparative examples, the initial magnetic permeability (initial μ in the table), the DC magnetic field H at which the magnetic permeability becomes 80% of the initial value, ｓａｔ (Hsat in the table) is obtained, and the obtained initial magnetic permeability and the DC magnetic field H ｓａｔ The value obtained by multiplying the value of Hsat by the value of μ (initial μ×Hsat in the table) was calculated. ｓａｔ The larger the value obtained by multiplying the initial magnetic permeability by the DC magnetic field H, the more the decrease in inductance due to magnetic saturation is suppressed, and the more excellent the DC bias characteristics of the magnetic material obtained. ｓａｔ The value obtained by multiplying the value by the initial magnetic permeability is referred to as the DC bias characteristic evaluation value. Each model was evaluated on a five-point scale of A, B, C, D, and E, in descending order of merit, based on the initial magnetic permeability and the DC bias characteristic evaluation value, as follows: Models with an evaluation of E were deemed to have failed, and all other models were deemed to have passed. A: The initial magnetic permeability was 9.0 H / m or more, and the DC bias characteristic evaluation value was 1090 or more. B: The initial magnetic permeability was 9.0 H / m or more, and the DC bias characteristic evaluation value was 680 or more but less than 1090. C: The initial magnetic permeability was 9.0 H / m or more, and the DC bias characteristic evaluation value was 660 or more but less than 680. D: The initial magnetic permeability was 5.5 H / m or more but less than 9.0 H / m, and the DC bias characteristic evaluation value was 620 or more but less than 660. E: The initial magnetic permeability was less than 5.5 H / m, or the DC bias characteristic evaluation value was less than 620.

[0096] The geometrical data and magnetic property data of the magnetic materials of Examples 1 to 21 and Comparative Examples 1 to 4 obtained by simulation are shown in Table 1.

[0097]

[0098] As shown in Table 1, in Comparative Examples 2 to 4, in which the average value of the δ / d value was greater than 0.087, the value of the interparticle distance 2δ relative to the circle-equivalent diameter d was large, resulting in a low packing density and a low initial magnetic permeability. On the other hand, in Comparative Example 1, in which the average value of the δ / d value was 0.087 or less, the standard deviation of the δ / d value was 0.097 or more, and the decrease in magnetic permeability resulted in a low resistance to the DC magnetic field H ｓａｔ The DC bias characteristic evaluation value, which evaluates the DC bias characteristic, was therefore small. This is presumably due to the large variation in the δ / d value and the non-uniform magnetic flux density distribution in the magnetic material.

[0099] On the other hand, according to the results of Examples 1 to 21, the standard deviation of the δ / d value was greater than 0 and not more than 0.092, and the average value of the δ / d value was 0.001 or more and 0.087 or less, thereby showing favorable values ​​in the initial magnetic permeability and DC bias characteristics. From the above, it was confirmed that, according to the present disclosure, by having an appropriate δ / d value, a magnetic material favorable in both the initial magnetic permeability and the DC bias characteristics can be obtained.

[0100] According to the results of Examples 7 to 10, the standard deviation and average value of the δ / d value were within the specified range, and in addition, the average value Δ of the interparticle distance 2δ was in the range of 3 μm to 90 μm, so that the initial permeability was 9.0 H / m or more and the DC bias characteristic evaluation value was 660 or more. Therefore, it was confirmed that by setting the average value Δ of the interparticle distance within the specified range, a magnetic material with better initial permeability and DC bias characteristics can be obtained.

[0101] According to the results of Example 11, it was confirmed that the standard deviation and average value of the δ / d value and the average value Δ of the interparticle distance were within the specified range, and that by having the D90 / D10 value of the metal magnetic particles be 1 or more and 5.5 or less, a magnetic material with even higher initial permeability and DC bias characteristics could be obtained.

[0102] The results of Examples 12 to 14 confirmed that the standard deviation and average value of the δ / d value and the average value Δ of the interparticle distance were within the specified ranges, and that by having the circularity of the metal magnetic particles be 0.78 or more and 0.91 or less, a magnetic material with even higher initial permeability and DC bias characteristics could be obtained.

[0103] The results of Examples 15 to 19 confirmed that when the standard deviation and average value of the δ / d value, the average interparticle distance Δ, the circularity, and the D90 / D10 values ​​were within the predetermined ranges, a magnetic material with even higher initial permeability and DC bias characteristics could be obtained.

[0104] The results of Examples 20 and 21 confirmed that the standard deviation and average value of the δ / d value, the average interparticle distance Δ, the circularity, and the D90 / D10 values ​​were all within the specified ranges, and that by having the average particle size of the metal magnetic particles be 5.0 μm or less, a magnetic material with even higher initial permeability and DC bias characteristics could be obtained.

[0105] The geometrical data and magnetic property data of the magnetic materials of Examples 22 and 23 obtained by simulation are shown in Table 2.

[0106]

[0107] According to the results of Example 22, in a magnetic material containing large-sized metal magnetic particles and small-sized metal magnetic particles, the standard deviation and average value of the δ / d value, as well as the average value Δ of the interparticle distance, were within a predetermined range, and thus a magnetic material with high initial magnetic permeability and DC bias characteristics was obtained.

[0108] According to the results of Example 23, it was confirmed that a magnetic material with high initial permeability and DC bias characteristics can be obtained by not only having the standard deviation and average value of the δ / d value and the average value Δ of the interparticle distance within a specified range, but also having the D90 / D10 value of the large-diameter metal magnetic particles within a specified range.

[0109] Unlike Examples 1 to 23, Examples 24 to 33 use alloy particles containing iron and nickel in various content ratios as the metal magnetic particles. Therefore, the preferred initial magnetic permeability and DC bias characteristic evaluation value are different from those of Examples 1 to 23. The magnetic materials of Examples 24 to 33 were comprehensively evaluated using the following evaluation criteria, with three levels of A, B, and C, in descending order of merit. Those with a rating of C were deemed to have failed, and all other materials were deemed to have passed. A: Initial magnetic permeability of 60 H / m or more and DC bias characteristic evaluation value of 90 or more B: Initial magnetic permeability of 30 H / m or more but less than 60 H / m, or DC bias characteristic evaluation value of 60 or more but less than 90 C: Initial magnetic permeability of less than 30 H / m, or DC bias characteristic evaluation value of less than 60

[0110] The geometrical data and magnetic property data of the magnetic materials of Examples 24 to 33 obtained by simulation are shown in Table 3.

[0111]

[0112] All of the magnetic materials of Examples 24 to 33 exhibited favorable values ​​for both initial magnetic permeability and DC bias characteristics. Furthermore, the magnetic materials of Examples 27 to 32, in which the Fe content of the metal magnetic particles was in the range of 35 atomic % or more and 65 atomic % or less, exhibited even higher initial magnetic permeability and DC bias characteristics than the magnetic materials of Examples 24 to 26 and 33, in which the Fe content was less than 35 atomic % or 70 atomic % or more.

[0113] REFERENCE SIGNS LIST 1: Magnetic material 2: Compact 10: Metal magnetic particle 10A: First metal magnetic particle 10B: Second metal magnetic particle 12: Outer surface 20: Insulating layer 20A: First insulating layer 20B: Second insulating layer 30: Composite particle 100, 200: Electronic component 110: Base body 120: Coil conductor 130: External electrode 210: Base body 220: Coil conductor

Claims

1. A magnetic material comprising a plurality of metal magnetic particles and an insulating layer covering each of the plurality of metal magnetic particles, wherein, in a cross-sectional view, any one of the plurality of metal magnetic particles is designated a first metal magnetic particle, and of the metal magnetic particles adjacent to the first metal magnetic particle, the metal magnetic particle closest to the first metal magnetic particle is designated a second metal magnetic particle, and wherein, when the circle-equivalent diameter of the first metal magnetic particle is designated d and the shortest distance between the surface of the first metal magnetic particle and the surface of the second metal magnetic particle is designated 2δ, the standard deviation of the δ / d value is greater than 0 and less than 0.092, and the average value of the δ / d value is between 0.001 and 0.

085.

2. The magnetic material according to claim 1, wherein the plurality of metal magnetic particles are adjacent to each other with the insulating layer interposed therebetween.

3. A magnetic material according to claim 1 or 2, wherein a first insulating layer covering the first metal magnetic particles and a second insulating layer covering the second metal magnetic particles are bonded to each other.

4. The magnetic material according to claim 3, wherein the shortest distance 2δ is the sum of the thickness of the first insulating layer and the thickness of the second insulating layer.

5. A magnetic material according to any one of claims 1 to 4, wherein the average value Δ of the shortest distance 2δ in a cross-sectional view is 0.006 μm or more and 0.18 μm or less.

6. The magnetic material according to any one of claims 1 to 5, wherein the particle size distribution curve of the plurality of metal magnetic particles has a single peak.

7. The magnetic material according to claim 6, wherein, in the cumulative particle size distribution curve of the metal magnetic particles, the particle size at which the cumulative value from the microparticle side reaches 10% is defined as D10 and the particle size at which the cumulative value reaches 90% is defined as D90, and the value of D90 / D10 is 1 or more and 5.5 or less.

8. The magnetic material according to claim 6 or 7, wherein the average circularity of the metal magnetic particles is 0.78 or more and 0.91 or less in cross section.

9. A magnetic material according to any one of claims 6 to 8, wherein D50, which is the particle size at which the cumulative value from the fine particle side reaches 50% in a cumulative particle size distribution curve of the metal magnetic particles, is 0.1 μm or more and 10 μm or less.

10. The magnetic material according to any one of claims 6 to 9, wherein the metal magnetic particles contain at least Fe and Ni, and the Fe content in the metal magnetic particles is 35 atomic % or more and 70 atomic % or less.

11. The magnetic material according to any one of claims 1 to 5, wherein the plurality of metal magnetic particles includes large particles having a large average particle size and small particles having a small average particle size.

12. A magnetic material according to claim 11, wherein, in a cumulative particle size distribution curve of the large particles, the value of D90 / D10 is 1 or more and 5.5 or less, where D10 is the particle size at which the cumulative value from the fine particle side reaches 10% and D90 is the particle size at which the cumulative value reaches 90%.

13. A magnetic material according to claim 11 or 12, wherein the average circularity of the large particles in cross section is 0.78 or more and 0.91 or less.

14. A magnetic material according to any one of claims 11 to 13, wherein D50, which is the particle size at which the cumulative value from the fine particle side reaches 50% in a cumulative particle size distribution curve of the large particles, is 0.1 μm or more and 10 μm or less.

15. A magnetic material according to any one of claims 11 to 14, wherein the large particles contain at least Fe and Ni, and the Fe content in the large particles is 35 atomic % or more and 65 atomic % or less.

16. An electronic component comprising an element body containing the magnetic material according to any one of claims 1 to 15 and a coil conductor.

17. An electronic component comprising the magnetic material according to any one of claims 1 to 15 and a coil wound around the magnetic material.

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