Magnetic materials and inductors

Abstract

The magnetic material (1) is composed of an aggregate of a plurality of magnetic particles (10). The first center of gravity position (G 10X ) is rotated 360 / n degrees (n is any integer greater than 6), the area of the first magnetic particle (10X) after rotation overlaps with the first magnetic particle (10X) before rotation by more than 90%. In the first planar region (P1), there are 9 to 11 centroid positions of the magnetic particles 10 on the rectangular first band portion (B1). For the magnetic particles (10) present in the first planar region (P1), when the 50% cumulative frequency distribution D50 based on the number of the maximum length in the first direction (d1) passing through the respective centroid positions in the first planar region (P1) is set to α, the 10% cumulative frequency distribution D10 is greater than 0.6α and the 90% cumulative frequency distribution D90 is less than 1.4α.

Description

Technical Field

[0001] The present invention relates to magnetic materials and inductors. Background Art

[0002] Power inductors employ a structure in which a coil conductor is covered with a resin containing magnetic powder. For example, Patent Document 1 discloses a power inductor comprising a unit body in which a coil conductor is embedded, and terminal electrodes formed on the exterior of the unit body and connected to the coil conductor. The unit body is characterized in that: the unit body comprises a first insulator, a coil conductor formed on the upper and lower surfaces of the first insulator, a second insulator formed to cover the coil conductor and the first insulator, and a third insulator formed to cover at least the upper and lower surfaces of the second insulator, and at least the third insulator is composed of an organic resin containing a flat metallic soft magnetic powder as a filler.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-67214 Summary of the Invention

[0006] Inductors such as those described in Patent Document 1 are expected to have good DC bias characteristics, meaning a high DC current value at which the inductance decreases by a certain amount due to magnetic saturation. This DC bias characteristic is a key factor in determining the rated current of an inductor. To achieve good DC bias characteristics, the magnetic material constituting the inductor must have a high DC current value at which the magnetic permeability decreases by a certain amount due to magnetic saturation.

[0007] According to Patent Document 1, inductors using metallic soft magnetic powder as filler have a higher maximum DC current before magnetic saturation than ferrite, resulting in better DC bias characteristics. However, from the perspective of improving the DC bias characteristics of magnetic materials, there is still room for improvement.

[0008] The present invention has been made to solve the above-mentioned problems, and its object is to provide a magnetic material having excellent DC superposition characteristics. Another object of the present invention is to provide an inductor using the magnetic material.

[0009] Solutions for solving problems

[0010] The inventors of this invention determined that by regularly arranging the magnetic particles constituting a magnetic material, the magnetic flux density passing through the material would be uniform, improving the DC superposition characteristics. Furthermore, the rated current and magnetic energy density of inductors using these magnetic particles would be improved. Based on this, they discovered a magnetic material structure that achieves these goals, leading to the completion of the present invention.

[0011] The magnetic material of the present invention is composed of an aggregate of multiple magnetic particles. In a first planar region observed using a scanning electron microscope or an optical microscope with 50 to 200 magnetic particles in a field of view, when the first magnetic particle's center of gravity, i.e., the first center of gravity, is rotated 360 / n degrees (n is an integer greater than or equal to 6), the rotated first magnetic particle overlaps with the first magnetic particle before rotation by at least 90% of its area. In first and second directions perpendicular to each other within the first planar region, defining the maximum length of the first magnetic particle passing through the first center of gravity as the first particle diameter and the second particle diameter, respectively, the first planar region contains nine to eleven centers of gravity of the magnetic particles within a first rectangular band centered on the first center of gravity, having a length five times the first particle diameter on either side in the first direction and a width equal to the second particle diameter in the second direction. For the magnetic particles existing in the above-mentioned first planar region, in the above-mentioned first planar region, when the 50% cumulative frequency distribution D50 based on the number of the maximum length in the above-mentioned first direction passing through each center of gravity position is set to α, the 10% cumulative frequency distribution D10 is greater than 0.6α and the 90% cumulative frequency distribution D90 is less than 1.4α.

[0012] The inductor of the present invention includes the above-mentioned magnetic material.

[0013] Effects of the Invention

[0014] According to the present invention, a magnetic material having excellent DC superposition characteristics can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a perspective view schematically showing an example of the magnetic material of the present invention.

[0016] Figure 2 This is a cross-sectional view schematically showing an example of magnetic particles constituting the magnetic material of the present invention.

[0017] Figure 3 It is a cross-sectional view schematically showing an example of the first plane region.

[0018] Figure 4 A. Figure 4 B. Figure 4 C and Figure 4 D is a cross-sectional view schematically showing an example of the shape of magnetic particles.

[0019] Figure 5 yes Figure 3 An enlarged view of the 1st plane area is shown.

[0020] Figure 6 It is a schematic diagram for explaining the first particle size and the second particle size of the first magnetic particle.

[0021] Figure 7 It is a schematic diagram for explaining the third particle diameter and the fourth particle diameter of the first magnetic particle.

[0022] Figure 8 This is a model diagram used in the simulation of Example 1-1.

[0023] Figure 9 This is a model diagram used in the simulation of Example 1-2.

[0024] Figure 10 This is a model diagram used in the simulation of Comparative Example 1-1.

[0025] Figure 11 This is a model diagram used in the simulation of Example 2-1.

[0026] Figure 12 This is a model diagram used in the simulation of Example 2-2.

[0027] Figure 13 This is a model diagram used in the simulation of Comparative Example 2-1.

[0028] Figure 14 This is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Example 1-1.

[0029] Figure 15 It is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Example 1-2.

[0030] Figure 16 It is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Comparative Example 1-1.

[0031] Figure 17 It is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Example 2-1.

[0032] Figure 18 This is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Example 2-2.

[0033] Figure 19 It is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Comparative Example 2-1.

[0034] Figure 20 This is a plan view schematically showing an example of the inductor of the present invention.

[0035] Figure 21 This is a perspective view schematically showing another example of the inductor of the present invention. DETAILED DESCRIPTION

[0036] Hereinafter, the magnetic material and inductor of the present invention will be described.

[0037] However, the present invention is not limited to the following configurations, and can be appropriately modified and used without changing the gist of the present invention. It should be noted that combinations of two or more of the preferred configurations of the present invention described below also belong to the present invention.

[0038] [Magnetic materials]

[0039] Figure 1 This is a perspective view schematically showing an example of the magnetic material of the present invention. Figure 2 This is a cross-sectional view schematically showing an example of magnetic particles constituting the magnetic material of the present invention.

[0040] Figure 1 The magnetic material 1 shown is composed of a plurality of magnetic particles 10. Figure 2 As shown, the surface of the magnetic particle 10 may be covered with an insulating film 20. If the surface of the magnetic particle 10 is covered with the insulating film 20, the generation of eddy currents large enough to penetrate multiple magnetic particles 10 can be suppressed. The insulating film 20 may cover a portion of the surface of the magnetic particle 10, but preferably covers the entire surface of the magnetic particle 10. It should be noted that the surface of the magnetic particle 10 does not necessarily have to be covered with the insulating film 20.

[0041] In this specification, when “magnetic particles” are described, unless otherwise specified, the term “magnetic particles” refers to particles that do not contain an insulating film, regardless of the presence or absence of an insulating film.

[0042] Figure 1 The magnetic material 1 shown has a periodic structure at least in the first planar region P1. The magnetic material 1 preferably further has a periodic structure in the second planar region P2. Figure 1 In the embodiment, the aggregate of the magnetic particles 10 has a face-centered cubic lattice structure, but is not limited to a periodic structure. Figure 1 In the embodiment, six layers of the magnetic grains 10 having a periodic structure in a plane parallel to the first planar region P1 are stacked, but the number of stacked magnetic grains 10 is not particularly limited.

[0043] Figure 3 It is a cross-sectional view schematically showing an example of the first plane region.

[0044] like Figure 3 As shown, observation is performed using a scanning electron microscope or an optical microscope, and the first planar region P1 is observed so that 50 to 200 magnetic particles 10 fit into one field of view.

[0045] In principle, when the particle diameter of the magnetic particles 10 is less than 50 μm, a scanning electron microscope is used, and when the particle diameter of the magnetic particles 10 is 50 μm or more, an optical microscope is used.

[0046] When observing the first planar region P1, it is necessary to find a cross section where the magnetic particles 10 are regularly arranged. For example, observe cross sections at approximately 5 to 10 locations in different directions and use the cross sections where the particle size variation of the magnetic particles 10 is minimal. The same applies when observing the second planar region P2.

[0047] In the first planar region P1, the center of gravity position of a certain magnetic particle (hereinafter referred to as the first magnetic particle 10X), that is, the first center of gravity position G 10X When the first magnetic particle 10X is rotated 360 / n degrees with n as the center, at least 90% of the area of the rotated first magnetic particle 10X overlaps with the area of the first magnetic particle 10X before the rotation. n can be any integer greater than 6. The lower limit of n can be any integer such as 7, 8, 9, or 10. For example, n is 6.

[0048] It should be noted that the center of gravity position of a magnetic particle does not refer to the center of gravity position of the magnetic particle in the strict sense. For example, it does not need to take into account the depth of the magnetic particle or the density unevenness within the particle. In other words, the center of gravity position of the magnetic particle 10 is only the center of gravity position with respect to the planar shape of the magnetic particle 10 appearing in the first planar region P1, and does not need to take into account the density unevenness in the planar shape. It refers to the center when the density is assumed to be uniform (i.e., the geometric center of the planar shape). Such a center of gravity position of the magnetic particle 10 can be specifically determined using image processing software, etc.

[0049] In this specification, when a magnetic particle is rotated 360 / n degrees with its center of gravity as the center, and the area overlaps by more than 90% with the area overlapped by the magnetic particle before rotation, it is defined as "the magnetic particle has C symmetry when n".

[0050] For a magnetic particle to have C symmetry when n is an integer, it is sufficient that the area of the magnetic particle before rotation overlaps with the area of the magnetic particle rotated 360 / n degrees by 90% or more. In other words, for an integer n ≥ 6, the above conditions only need to be met. For example, it is not necessary to have a 90% or more area overlap between the rotated magnetic particle and the unrotated magnetic particle after rotation by 2 × 360 / n degrees. However, for all integers k from 1 to n-1, it is preferable that the area of the rotated magnetic particle overlap with the area of the unrotated magnetic particle by 90% or more when rotating by k × 360 / n degrees.

[0051] In order for the magnetic particles to have C symmetry when n is present, only one n is required to satisfy C symmetry. However, it is preferred that C symmetry be satisfied when multiple n (non-prime numbers such as n=6, n=8, etc.) are present.

[0052] Figure 4 A. Figure 4 B. Figure 4 C and Figure 4 D is a cross-sectional view schematically showing an example of the shape of magnetic particles.

[0053] Figure 4 The magnetic particle 10A shown in A has a circular (perfectly circular) shape. Therefore, when n = 2, 3, 4, 5, 6, 7, 8, 9 or 10, C symmetry holds. In the case where the magnetic particle has a circular (perfectly circular) shape, it can be said that C symmetry holds when n is "any integer greater than 6", and therefore, the above relationship is satisfied. In the case where the magnetic particle has a circular (perfectly circular) shape, it can be said that C symmetry also holds when n is "any integer greater than 7".

[0054] Figure 4 The magnetic particle 10B shown in B has a regular hexagonal shape. Therefore, C symmetry holds when n=2, 3, or 6. In this case, C symmetry holds when n=6, and thus the above-mentioned relationship is satisfied.

[0055] Figure 4 The magnetic particle 10C shown by C has a regular octagonal shape. Therefore, C symmetry holds when n=2, 4, or 8. In this case, C symmetry holds when n=8, and thus the above-mentioned relationship is satisfied.

[0056] Figure 4 The magnetic particle 10D shown in D has a regular decagonal shape. Therefore, C symmetry holds when n=2, 4, 5, or 10. In this case, C symmetry holds when n=10, and thus the above-mentioned relationship is satisfied.

[0057] The shape of the magnetic particle 10 having C-symmetry when n is not a specific value is not limited, as long as the area of the magnetic particle 10 after rotation overlaps by 90% or more with the area of the magnetic particle 10 before rotation when the magnetic particle 10 is rotated 360 / n degrees. The shape of the magnetic particle 10 does not need to be an idealized circle, ellipse, or regular polygon. For example, if the magnetic particle 10 is polygonal, some corners may be rounded.

[0058] Among the magnetic particles 10 present in the first planar region P1, the magnetic particle 10 having C symmetry when n is at least the first magnetic particle 10X is sufficient, but it is preferable that the first magnetic particle 10X be as described below. Figure 5All the magnetic particles 10 present on the first band portion B1 shown are more preferably all the magnetic particles 10 present on the first band portion B1 and the second band portion B2, further preferably all the magnetic particles 10 within the first circular region C1, further preferably all the magnetic particles 10 within the first circular region C1 and the second circular region C2, and particularly preferably all the magnetic particles 10 within the first planar region P1. In the case where the plurality of magnetic particles 10 present in the first planar region P1 have C symmetry for n, all the magnetic particles 10 do not need to have C symmetry for the same n. For example, the shapes of the magnetic particles 10 having C symmetry may be different from each other, and may satisfy C symmetry for different n. In addition, magnetic particles 10 having C symmetry for a certain n1 and magnetic particles 10 having C symmetry for n2 instead of n1 may be arranged alternately.

[0059] Figure 5 yes Figure 3 An enlarged view of the 1st plane area is shown. Figure 6 It is a schematic diagram for explaining the first particle size and the second particle size of the first magnetic particle. Figure 7 It is a schematic diagram for explaining the third particle diameter and the fourth particle diameter of the first magnetic particle.

[0060] like Figure 5 and Figure 6 As shown in FIG. 1 , the first direction d1 and the second direction d2 that are orthogonal to each other in the first plane region P1 will pass through the first centroid position G 10X The maximum lengths of the first magnetic particles 10X are defined as the first particle diameter x1 and the second particle diameter x2. Figure 5 As shown, in the first plane region P1, at the first center of gravity position G 10X There are 9 to 11 magnetic particles 10 having their center of gravity located on the first band portion B1, which is a rectangle with a length of 5 times the first particle diameter x1 on both sides in the first direction d1 and a width equal to the second particle diameter x2 in the second direction d2. Figure 5 In the example shown, the center-of-gravity positions of nine magnetic particles 10 exist on the first band portion B1.

[0061] In this specification, when the relationship of the center of gravity positions of 9 to 11 magnetic particles exists on the first band portion in the first plane region, it is defined as "the magnetic particles have periodicity in the first plane region."

[0062] Furthermore, if Figure 5 and Figure 7 As shown, in the first plane region P1, the third direction d3 intersecting the first direction d1 and the fourth direction d4 perpendicular to the third direction d3 will pass through the first centroid position G 10XThe maximum lengths of the first magnetic particles 10X are defined as the third particle diameter x3 and the fourth particle diameter x4. Figure 5 As shown, in the first plane region P1, at the first center of gravity position G 10X The center of gravity of 9 to 11 magnetic particles 10 is preferably present on the second band portion B2 of a rectangle having a length of 5 times the third particle diameter x3 on both sides in the third direction d3 and a width equal to the fourth particle diameter x4 in the fourth direction d4. Figure 5 In the example shown, the magnetic particles 10 are circular in shape, and therefore, nine centers of gravity of the magnetic particles 10 are also present on the second band portion B2. The number of magnetic particles 10 with centers of gravity on the second band portion B2 may be the same as or different from the number of magnetic particles 10 with centers of gravity on the first band portion B1.

[0063] As described above, the particle size of the magnetic particles 10 referred to in this specification is different from the actual particle size of the three-dimensionally shaped magnetic particles 10. For example, for each magnetic particle 10 in the first planar region P1, the maximum length passing through the center of gravity is measured along a certain direction and used as the particle size of the magnetic particle 10 in the first planar region P1.

[0064] In addition, if Figure 5 As shown, the first center of gravity position G 10X The area enclosed by a circle having a radius five times the first particle diameter x1 as the center is defined as the first circular area C1. 10X The area enclosed by a circle with a radius of 5 times the third particle diameter x3 as the center is defined as the second circular area C2. Figure 5 In the example shown, the shape of the first magnetic particle 10X is circular, and therefore the first circular region C1 and the second circular region C2 coincide with each other.

[0065] exist Figure 5 In the example shown, the aggregate of magnetic particles 10 has a face-centered cubic lattice structure. Therefore, the angle between the first direction d1 and the third direction d3 in the first planar region P1 is 60 degrees. The angle between the first direction d1 and the third direction d3 is not particularly limited and is, for example, 20 to 160 degrees. The angle between the first direction d1 and the third direction d3 is preferably 55 to 65 degrees.

[0066] In addition, for the magnetic particles 10 existing in the first planar region P1, when the 50% cumulative frequency distribution D50 based on the number of the maximum length in the first direction d1 passing through each center of gravity position in the first planar region P1 is set to α, the 10% cumulative frequency distribution D10 is greater than 0.6α, and the 90% cumulative frequency distribution D90 is less than 1.4α.

[0067] Specifically, for the magnetic particles 10 present in the first planar region P1, the maximum length in the first direction d1 passing through the respective center of gravity positions in the first planar region P1 is measured to calculate D10, D50, and D90. The same applies to the particle size of the magnetic particles 10 present in the second planar region P2.

[0068] In this specification, for the magnetic particles existing in the above-mentioned first plane region, when the 50% cumulative frequency distribution D50 based on the number of the maximum length in the first direction passing through each center of gravity position is set to α, the 10% cumulative frequency distribution D10 is greater than 0.6α and the 90% cumulative frequency distribution D90 is less than 1.4α. If this relationship holds, it is defined as "the magnetic particles have narrow dispersion in the first plane region."

[0069] For the magnetic particles 10 existing in the first planar region P1, it is preferred that: when the 50% cumulative frequency distribution D50 based on the number of the maximum length in the first direction d1 passing through the respective center of gravity positions in the first planar region P1 is set to α, the 10% cumulative frequency distribution D10 is greater than 0.9α and the 90% cumulative frequency distribution D90 is less than 1.1α.

[0070] In the magnetic material 1, further observation is performed using a scanning electron microscope or an optical microscope with 50 to 200 magnetic particles entering one field of view, and a second plane region P2 that is not on the same plane as the first plane region P1 can also be observed (see Figure 1 ).

[0071] The angle formed by the first planar region P1 and the second planar region P2 is not particularly limited, and is, for example, 20 degrees to 160 degrees.

[0072] In the second planar region P2, when the center of gravity position of a certain magnetic particle (hereinafter referred to as the second magnetic particle), that is, the second center of gravity position, is rotated 360 / m degrees, it is preferred that the second magnetic particle after rotation overlaps with the second magnetic particle before rotation by more than 90% of its area. That is, in the second planar region P2, the second magnetic particle preferably has C symmetry when it is m. In the above, m can be any integer greater than 6. The lower limit of m can be any integer such as 7, 8, 9 or 10. For example, m is 6. It can be m=n or m≠n.

[0073] For a magnetic particle to have C symmetry when m is an integer, it is sufficient that the area of the magnetic particle before rotation overlaps with the area of the magnetic particle rotated 360 / m degrees by 90% or more. In other words, for integers m ≥ 6, the above conditions only need to be met. For example, it is not necessary to have a 90% or more area overlap between the rotated magnetic particle and the unrotated magnetic particle when rotating 2 × 360 / m degrees. However, for all integers k from 1 to m-1, it is preferable that the area of the rotated magnetic particle overlap with the area of the unrotated magnetic particle by 90% or more when rotating k × 360 / m degrees.

[0074] In order for the magnetic particles to have C symmetry when m is present, only one m is required to satisfy C symmetry. However, it is preferred that C symmetry be satisfied when multiple m (non-prime numbers such as m=6, m=8, etc.) are present.

[0075] The shape of the magnetic particle 10 having C symmetry at m is not particularly limited, as long as the area of the rotated magnetic particle 10 overlaps by at least 90% with the area of the magnetic particle 10 before rotation when the magnetic particle 10 is rotated 360 / m. The shape of the magnetic particle 10 does not need to be an idealized circle, ellipse, or regular polygon. For example, if the magnetic particle 10 is polygonal, some corners may be rounded.

[0076] The second magnetic particle is preferably a particle different from the first magnetic particle 10X. The shape of the second magnetic particle may be the same as or different from the shape of the first magnetic particle 10X.

[0077] Among the magnetic particles 10 present in the second planar region P2, the magnetic particles 10 having C symmetry when m is at least the second magnetic particle, but preferably all the magnetic particles 10 present in the third band portion described later, more preferably all the magnetic particles 10 present in the third band portion and the fourth band portion, further preferably all the magnetic particles 10 within the third circular region, further preferably all the magnetic particles 10 within the third circular region and the fourth circular region, and particularly preferably all the magnetic particles 10 within the second planar region P2. In the case where a plurality of magnetic particles 10 present in the second planar region P2 have C symmetry when m is, all the magnetic particles 10 do not need to have C symmetry for the same m. For example, the shapes of the magnetic particles 10 having C symmetry may be different from each other, and may satisfy C symmetry for different m. In addition, magnetic particles 10 having C symmetry for a certain m1 and magnetic particles 10 having C symmetry for m2 instead of m1 may be arranged alternately.

[0078] In the second planar region P2, the maximum length of the second magnetic particle passing through the second center of gravity position in the fifth and sixth directions, which are orthogonal to each other, is defined as the fifth particle diameter and the sixth particle diameter, respectively. In the second planar region P2, the center of gravity positions of 9 to 11 magnetic particles 10 are preferably present in the third rectangular band portion centered on the second center of gravity position, having a length five times the fifth particle diameter on either side in the fifth direction and a width equal to the sixth particle diameter in the sixth direction.

[0079] Furthermore, within the second planar region P2, the maximum length of the second magnetic particle passing through the second center of gravity position in the seventh direction intersecting the fifth direction and the eighth direction orthogonal to the seventh direction is defined as the seventh particle diameter and the eighth particle diameter, respectively. In the second planar region P2, preferably, nine to eleven centers of gravity of magnetic particles 10 are present in the fourth band portion, which is a rectangle centered on the second center of gravity position, with a length five times the seventh particle diameter on either side in the seventh direction and a width equal to the eighth particle diameter in the eighth direction. The number of magnetic particles 10 with centers of gravity in the fourth band portion may be the same as or different from the number of magnetic particles 10 with centers of gravity in the third band portion.

[0080] In addition, the area surrounded by a circle with a radius of 5 times the 5th particle size and the second center of gravity as the center is defined as the third circular area. Similarly, the area surrounded by a circle with a radius of 5 times the 7th particle size and the second center of gravity as the center is defined as the fourth circular area. The third circular area and the fourth circular area may be the same.

[0081] The angle formed by the fifth direction and the seventh direction is not particularly limited, and is, for example, 20 to 160 degrees. The angle formed by the fifth direction and the seventh direction is preferably 55 to 65 degrees.

[0082] Furthermore, for the magnetic particles 10 present in the second planar region P2, when β is defined as the number-based 50% cumulative frequency distribution D50 of the maximum length in the fifth direction passing through the respective center of gravity positions in the second planar region P2, it is preferred that the 10% cumulative frequency distribution D10 is 0.6β or greater and the 90% cumulative frequency distribution D90 is 1.4β or less, and more preferably the 10% cumulative frequency distribution D10 is 0.9β or greater and the 90% cumulative frequency distribution D90 is 1.1β or less. β may be equal to α or β≠α.

[0083] In the magnetic material 1, by making the magnetic particles 10 have C symmetry when n is 5, it becomes a driving force for generating a periodic structure and can control the deformation of the magnetic flux. If n of the C symmetry is 5 or less, the angle of the corner of the cross-sectional shape of the magnetic particle 10 becomes sharp, and the magnetic flux tends to concentrate at its corner. Therefore, by making n of the C symmetry be 6 or more, the concentration of the magnetic flux can be prevented. From the viewpoint of preventing the concentration of the magnetic flux, it is preferred that C symmetry is satisfied when there are multiple n, that is, there are multiple n that satisfy C symmetry, and the more n that satisfy C symmetry, the better. In particular, the shape of the magnetic particle 10 is preferably Figure 4 The circle (perfect circle) indicated by A. The same also applies when the magnetic particle 10 has C symmetry when m is the number.

[0084] Furthermore, by providing the magnetic particles 10 with periodicity, the density of the magnetic flux can be minimized, thereby making the magnetic flux density uniform.

[0085] Furthermore, by providing the magnetic particles 10 with narrow dispersion, this becomes a driving force for generating a periodic structure.

[0086] As described above, by regularly arranging the magnetic grains 10 constituting the magnetic material 1 , the magnetic flux density passing through the magnetic material 1 becomes uniform, thereby improving the DC superposition characteristics.

[0087] The material constituting the magnetic particles 10 is not particularly limited. The magnetic particles 10 preferably contain at least one element selected from the group consisting of Fe, Ni, Co, C, Si, and Cr. Examples of the magnetic particles 10 include Ni-P particles containing Ni and P, Fe particles, Fe-Si particles, Fe-Si-Cr particles, Fe-Si-B particles, Fe-Si-B-Cu-Nb particles, Fe-Si-B-P-Cu particles, Fe-Ni particles, and Fe-Co particles.

[0088] The particle size of the magnetic particles 10 is not particularly limited; however, a larger particle size reduces the surface area of the particles. In particular, when the surface of the magnetic particles 10 is charged, by setting the particle size of the magnetic particles 10 to the μm level rather than the nm level, the amount of static charge on the surface can be reduced, thereby significantly achieving the effects of the present invention.

[0089] For example, the first particle size x1 of the first magnetic particle 10X is preferably 0.5 μm to 80 μm, more preferably 0.6 μm to 50 μm, and even more preferably 1 μm to 30 μm. In this case, the above-mentioned α is preferably 0.5 μm to 80 μm, more preferably 0.6 μm to 50 μm, and even more preferably 1 μm to 30 μm. Similarly, the second particle size x2 of the first magnetic particle 10X is preferably 0.5 μm to 80 μm, more preferably 0.6 μm to 50 μm, and even more preferably 1 μm to 30 μm; the third particle size x3 is preferably 0.5 μm to 80 μm, more preferably 0.6 μm to 50 μm, and even more preferably 1 μm to 30 μm; and the fourth particle size x4 is preferably 0.5 μm to 80 μm, more preferably 0.6 μm to 50 μm, and even more preferably 1 μm to 30 μm. The first particle diameter x1, the second particle diameter x2, the third particle diameter x3, and the fourth particle diameter x4 of the first magnetic particle 10X may be the same as or different from each other.

[0090] In addition, the fifth particle size of the second magnetic particle is preferably 0.5 μm to 80 μm, more preferably 0.6 μm to 50 μm, and even more preferably 1 μm to 30 μm. In this case, the above-mentioned β is preferably 0.5 μm to 80 μm, more preferably 0.6 μm to 50 μm, and even more preferably 1 μm to 30 μm. Similarly, the sixth particle size of the second magnetic particle is preferably 0.5 μm to 80 μm, more preferably 0.6 μm to 50 μm, and even more preferably 1 μm to 30 μm; the seventh particle size is preferably 0.5 μm to 80 μm, more preferably 0.6 μm to 50 μm, and even more preferably 1 μm to 30 μm; and the eighth particle size is preferably 0.5 μm to 80 μm, more preferably 0.6 μm to 50 μm, and even more preferably 1 μm to 30 μm. The fifth, sixth, seventh, and eighth particle sizes of the second magnetic particle may be the same or different.

[0091] Magnetic particles 10 can be obtained, for example, by mixing an aqueous metal salt solution with an aqueous reducing agent solution to form the core of the microparticles, and then subjecting these cores to electroless reduction to precipitate the metal. This method, known as the electroless reduction method, yields metal particles that are nearly perfect spheres. This allows for stable, efficient, and low-cost mass production of particles with a desired particle size, symmetry, and narrow dispersion.

[0092] Furthermore, by using the pulsed orifice ejection method (POEM) or the uniform droplet spray method (UDS), metal particles of the order of μm, which are close to true spheres, can be obtained with narrow dispersion.

[0093] The magnetic particles thus obtained are precipitated in a solvent having a light specific gravity (for example, an alkane-containing solvent such as isopropyl alcohol), whereby the magnetic particles can be arranged in the above-mentioned periodic structure.

[0094] Generally speaking, the sedimentation velocity of particles increases as the square of the particle diameter. Therefore, it is preferable to increase the particle diameter of the magnetic particles to promote the sedimentation of the magnetic particles.

[0095] Furthermore, in consideration of the sedimentation of the magnetic particles, it is preferable to form a periodic structure corresponding to the particle size in advance.

[0096] Furthermore, after arranging particles close to true spheres into a periodic structure using the above method, calcining the particles can yield particles with a cross-sectional shape close to a regular hexagon. Specifically, heating the magnetic particles near their softening temperature causes the particles to weld together, achieving C symmetry of n=6.

[0097] For particles having other shapes, known methods may be used.

[0098] As described above, the surface of the magnetic particle 10 may be covered with the insulating film 20 .

[0099] The material constituting the insulating film 20 is not particularly limited and may or may not be polar. When the insulating film 20 is polar, it charges the surface of the magnetic particles 10, creating a metastable state between the particles due to electrostatic repulsion and van der Waals attraction. As a result, the periodic structure of the magnetic particles 10 is spontaneously generated. For example, the insulating film 20 can be formed by calcining Fe—Si—Cr particles in an oxygen atmosphere to oxidize their surfaces.

[0100] The insulating film 20 preferably contains at least two elements selected from the group consisting of C, N, O, P, and Si. The insulating film 20 containing these elements has polarity and can charge the surface of the magnetic particle 10 .

[0101] The elements contained in the insulating film 20 can be confirmed by elemental analysis using, for example, a scanning transmission electron microscope (STEM)-energy dispersive X-ray device (EDX).

[0102] The insulating film 20 preferably contains a hydroxyl group or a carbonyl group, and more preferably contains a hydroxyl group and a carbonyl group. The hydroxyl group and the carbonyl group are polar functional groups, and thus the insulating film 20 can charge the surface of the magnetic particle 10 .

[0103] The functional groups included in the insulating film 20 can be confirmed by, for example, Fourier transform infrared spectroscopy (FT-IR).

[0104] Specifically, the insulating film 20 includes an inorganic oxide and a water-soluble polymer.

[0105] Examples of the metal species constituting the inorganic oxide include at least one selected from the group consisting of Li, Na, Mg, Al, Si, K, Ca, Ti, Cu, Sr, Y, Zr, Ba, Ce, Ta, and Bi. Among these, Si, Ti, Al, or Zr is preferred in consideration of the strength and inherent resistivity of the resulting oxide. The aforementioned metal species are metals of the metal alkoxide used to form the insulating film 20. Specific examples of the inorganic oxide include SiO2, TiO2, Al2O3, or ZrO, with SiO2 being particularly preferred.

[0106] The inorganic oxide is preferably contained in an amount within a range of 0.01 wt % to 5 wt % based on the total weight of the magnetic particles 10 and the insulating film 20 .

[0107] Examples of the water-soluble polymer include at least one of polyethyleneimine, polyvinyl pyrrolidone, polyethylene glycol, sodium polyacrylate, carboxymethyl cellulose, polyvinyl alcohol, and gelatin.

[0108] The water-soluble polymer is preferably contained in an amount within a range of 0.01 wt % to 1 wt % based on the total weight of the magnetic particles 10 and the insulating film 20 .

[0109] The thickness of the insulating film 20 is not particularly limited. However, by thinning the insulating film 20, the spatial filling rate of the magnetic particles 10 is increased, thereby achieving a high inductance. Furthermore, variations in effective magnetic permeability due to variations in the thickness of the insulating film 20 can be suppressed, thereby reducing variations in inductance.

[0110] When a region containing one magnetic particle 10 is defined as a unit cell, the length of the insulating film 20 that passes through the center of gravity of the magnetic particle 10 in the first direction d1 in the unit cell is defined as the thickness of the insulating film 20 .

[0111] For example, the thickness of the insulating film 20 covering the surface of the first magnetic particle 10X is preferably 10% or less of the first particle diameter x1 of the first magnetic particle 10X. In particular, the thickness of the insulating film 20 covering the surface of the magnetic particles 10 present in the first planar region P1 is preferably 10% or less of the particle diameter of each magnetic particle 10. In this case, the reduction in the ratio of magnetic particles corresponding to the thickness of the insulating film can be suppressed, thereby achieving high inductance.

[0112] On the other hand, the thickness of the insulating film 20 covering the surface of the first magnetic particle 10X is preferably not less than 0.1% of the first particle diameter x1 of the first magnetic particle 10X. In particular, the thickness of the insulating film 20 covering the surface of the magnetic particles 10 present in the first planar region P1 is preferably not less than 0.1% of the particle diameter of each magnetic particle 10. In this case, the increase in eddy currents due to a decrease in insulation properties can be suppressed, and the periodicity of the structure due to polarization of the insulating film can be improved.

[0113] Specifically, the thickness of the insulating film 20 covering the surface of the first magnetic particle 10X is preferably 30,000 nm or less, and preferably 10 nm or more. Furthermore, the thickness of the insulating film 20 covering the surface of the magnetic particle 10 present in the first planar region P1 is preferably 30,000 nm or less, and preferably 10 nm or more.

[0114] Furthermore, the thickness of the insulating film 20 covering the surface of the second magnetic particle is preferably no greater than 10% of the fifth particle diameter of the second magnetic particle. In particular, the thickness of the insulating film 20 covering the surface of the magnetic particle 10 present in the second planar region P2 is preferably no greater than 10% of the particle diameter of each magnetic particle 10. On the other hand, the thickness of the insulating film 20 covering the surface of the second magnetic particle is preferably no greater than 0.1% of the fifth particle diameter of the second magnetic particle. In particular, the thickness of the insulating film 20 covering the surface of the magnetic particle 10 present in the second planar region P2 is preferably no greater than 0.1% of the particle diameter of each magnetic particle 10.

[0115] Specifically, the thickness of the insulating film 20 covering the surface of the second magnetic particle is preferably 30,000 nm or less, and preferably 10 nm or more. Furthermore, the thickness of the insulating film 20 covering the surface of the magnetic particle 10 present in the second planar region P2 is preferably 30,000 nm or less, and preferably 10 nm or more.

[0116] The thickness of the insulating film 20 can be measured using, for example, an optical microscope, a scanning electron microscope, or a transmission electron microscope. Alternatively, it can be measured using EDX.

[0117] It should be noted that, in principle, when the thickness of the insulating film 20 is less than 200 nm, a transmission electron microscope is used; when the thickness of the insulating film 20 is greater than 200 nm and less than 50,000 nm, a scanning electron microscope is used; and when the thickness of the insulating film 20 is greater than 50,000 nm, an optical microscope is used.

[0118] The insulating film 20 can be formed by the following method described in International Publication No. 2016 / 056351, for example.

[0119] (1) The magnetic particles 10 are dispersed in a solvent.

[0120] (2) Add metal alkoxide and water-soluble polymer to the solvent and stir.

[0121] At this time, the metal alkoxide is hydrolyzed, and as a result, an insulating film 20 containing a metal oxide, which is a hydrolyzate of the metal alkoxide, and a water-soluble polymer is formed on the surface of the magnetic particle 10 .

[0122] As the solvent, alcohols such as methanol and ethanol can be used.

[0123] Examples of the metal species M of the metal alkoxide having the M-OR structure include at least one selected from the group consisting of Li, Na, Mg, Al, Si, K, Ca, Ti, Cu, Sr, Y, Zr, Ba, Ce, Ta, and Bi. Among these, Si, Ti, Al, or Zr is preferred, considering the strength and inherent resistivity of the resulting oxide. Examples of the alkoxy group OR of the metal alkoxide include methoxy, ethoxy, and propoxy. Two or more metal alkoxides may be combined.

[0124] To accelerate the hydrolysis rate of the metal alkoxide, a catalyst may be added as needed. Examples of the catalyst include acidic catalysts such as hydrochloric acid, acetic acid, and phosphoric acid; alkaline catalysts such as ammonia, sodium hydroxide, and piperidine; and salt catalysts such as ammonium carbonate and ammonium acetate.

[0125] The stirred dispersion can be dried by an appropriate method (oven, spray, vacuum, etc.) The drying temperature is, for example, 50° C. to 300° C. The drying time can be appropriately set, for example, 10 minutes to 24 hours.

[0126] Alternatively, the insulating film 20 can be formed by coating the surface of the magnetic particle 10 with a phosphate solution.

[0127] Hereinafter, in order to evaluate the characteristics of the magnetic material of the present invention, a static magnetic field two-dimensional analysis was performed using a simulator (Femtet 2019 manufactured by Murata Manufacturing Co., Ltd.) It should be noted that the present invention is not limited to these Examples.

[0128] In the model shown below, the overall size of the model is 1.18 mm × 1.18 mm, and 49 magnetic particles are arranged.

[0129] Figure 8 This is a model diagram used in the simulation of Example 1-1. Figure 9 This is a model diagram used in the simulation of Example 1-2. Figure 10 This is a model diagram used in the simulation of Comparative Example 1-1. Figure 8 、 Figure 9 and Figure 10In the embodiment, magnetic particles having circular (perfect circle), regular hexagonal, and square shapes are arranged in a square lattice.

[0130] Figure 11 This is a model diagram used in the simulation of Example 2-1. Figure 12 This is a model diagram used in the simulation of Example 2-2. Figure 13 This is a model diagram used in the simulation of Comparative Example 2-1. Figure 11 、 Figure 12 and Figure 13 In the embodiment, magnetic particles having circular (perfect circle), regular hexagonal, and square shapes are arranged in a hexagonal lattice.

[0131] The mesh condition is set to use G2, 1 secondary component, the surface cut is set to the minimum cut number 16, the standard mesh size is set to 0.112mm, the coil and air are set to a mesh size of 0.01mm, the external boundary conditions are set to electric wall and magnetic wall, and the model thickness is set to 1mm.

[0132] The physical properties of iron particles as magnetic particles, that is, the relationship between the magnetic flux density B and the magnetic field H as magnetization characteristics are defined by equation (1).

[0133] B=0.8·tanh(0.011·H) (1)

[0134] When the magnetic field H is 0 [A / m] to 400 [A / m], the magnetic flux density B derived from the formula (1) is input.

[0135] The insulating film was nonmagnetic, the area filling rate of the magnetic particles was 28%, the projections of the magnetic particles were perfect circles, regular hexagons, and squares with the same area, the particle size was 100 μm, and there was air between the particles.

[0136] The effective relative magnetic permeability at 0.85 A / m is taken as the initial effective relative magnetic permeability μ i , and find 0.7μ i The magnetic field H 30 .

[0137] Figure 14 This is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Example 1-1. Figure 15 It is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Example 1-2. Figure 16 It is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Comparative Example 1-1.

[0138] Figure 17 It is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Example 2-1. Figure 18This is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Example 2-2. Figure 19 It is a graph showing the relationship between the effective relative magnetic permeability μ and the magnetic field H in Comparative Example 2-1.

[0139] In addition, the magnetic energy density defined below was obtained.

[0140] ∫μHdB (integral range 0~μ i ×H 30 )

[0141] The H in Example 1-1, Example 1-2 and Comparative Example 1-1 was 30 , initial effective relative permeability μ i The magnetic energy density is shown in Table 1. The H 30 , initial effective relative permeability μ i and magnetic energy density are shown in Table 2.

[0142] [Table 1]

[0143]

[0144] [Table 2]

[0145]

[0146] According to Table 1, when the magnetic particles are arranged in a square lattice, the circular magnetic particles in Example 1-1 and the regular hexagonal magnetic particles in Example 1-2 are compared with the square magnetic particles in Comparative Example 1-1. 30 Furthermore, Example 1-1 and Example 1-2 can obtain higher magnetic energy density than Comparative Example 1-1.

[0147] According to Table 2, when the magnetic particles are arranged in a hexagonal lattice, the magnetic particles in Example 2-1 and Example 2-2, which are circular and regular hexagonal, are arranged in a hexagonal lattice, respectively, compared with Comparative Example 2-1, which is square. 30 Furthermore, Example 2-1 and Example 2-2 can obtain higher magnetic energy density than Comparative Example 2-1.

[0148] [Inductor]

[0149] An inductor including the magnetic material of the present invention is also one aspect of the present invention.

[0150] Figure 20 This is a plan view schematically showing an example of the inductor of the present invention.

[0151] Figure 20 The inductor 100 shown includes a core portion 110 and a conductor wire 120 wound around the core portion 110 .

[0152] The core 110 includes the magnetic material of the present invention (e.g., Figure 1 Magnetic material 1 shown, etc.).

[0153] The conductor wire 120 is made of, for example, copper or a copper alloy.

[0154] Figure 21 This is a perspective view schematically showing another example of the inductor of the present invention.

[0155] Figure 21 The inductor 200 shown includes a unit cell 210 made of the magnetic material of the present invention, an external electrode 220 provided on a surface of the unit cell 210 , and a coil conductor 230 provided inside the unit cell 210 .

[0156] The inductor of the present invention is not limited to the configuration shown in inductor 100 or 200 , and various applications and modifications can be applied to the configuration, manufacturing method, etc. of the inductor within the scope of the present invention.

[0157] For example, the winding method of the coil conductor may be any of α-winding, random winding, edgewise winding, and aligned winding.

[0158] The magnetic material of the present invention is not limited to the structure shown in Magnetic Material 1 , and various applications and modifications can be applied to the structure, production method, etc. of the magnetic material within the scope of the present invention.

[0159] For example, the magnetic material of the present invention may further contain a resin. When the magnetic material of the present invention contains a resin in addition to magnetic particles, curing the resin can produce a molded article in which the magnetic particles are arranged and dispersed in the resin. In this manner, the magnetic particles arranged and dispersed in the resin are also included in the aggregate of magnetic particles.

[0160] When the magnetic material of the present invention includes a resin, the type of resin is not particularly limited and can be appropriately selected according to desired properties and applications. Examples of the resin include epoxy resins, silicone resins, phenolic resins, polyamide resins, polyimide resins, and polyphenylene sulfide resins.

[0161] In the magnetic material of the present invention, the C-symmetry of the magnetic particles about n is sufficient if the area of the magnetic particles that overlap after rotation is 90% or greater. Therefore, the area of the magnetic particles that overlap after rotation does not necessarily need to be 100% and may, for example, be 99% or less. The same applies to the C-symmetry of the magnetic particles about m.

[0162] In the magnetic material of the present invention, the periodicity of the magnetic grains in the first planar region only requires that the number of magnetic grains whose centers of gravity are aligned in the first band portion be 9 to 11. Therefore, the number of magnetic grains whose centers of gravity are aligned in the first band portion is not necessarily 9, but may also be 10 or 11. The same applies to the periodicity of the magnetic grains in the second planar region.

[0163] In the magnetic material of the present invention, for the narrow dispersion of magnetic particles in the first planar region, D10 only needs to be 0.6α or greater, and D90 only needs to be 1.4α or less. Therefore, D10 = D90 = α is not necessarily required; for example, D10 may be 0.99α or less and D90 may be 1.01α or greater. The same applies to the narrow dispersion of magnetic particles in the second planar region.

[0164] Explanation of symbols

[0165] 1 Magnetic materials

[0166] 10, 10A, 10B, 10C, 10D magnetic particles

[0167] 10X 1st magnetic particles

[0168] 20 Insulation film

[0169] 100, 200 inductors

[0170] 110 Nuclear Department

[0171] 120 conductor wire

[0172] 210 units

[0173] 220 external electrodes

[0174] 230 Coil conductor

[0175] d1 1st direction

[0176] d2 2nd direction

[0177] d3 3rd direction

[0178] d4 4th direction

[0179] x1 1st particle size

[0180] x2 2nd particle size

[0181] x3 3rd particle size

[0182] x4 4th particle size

[0183] B1 1st band

[0184] B2 Second band

[0185] C1 1st circle area

[0186] C2 2nd circle area

[0187] G 10X 1st center of gravity position

[0188] P1 1st plane area

[0189] P2 Second plane area

Claims

1. A magnetic material consisting of an aggregate of multiple magnetic particles; In a first plane region observed using a scanning electron microscope or an optical microscope so that 50 to 200 magnetic particles fit into one field of view, When the first magnetic particle is rotated 360 / n degrees around the first center of gravity position of the first magnetic particle in the first planar region, the first magnetic particle after rotation overlaps with the first magnetic particle before rotation by more than 90% of its area, wherein Said n is any integer greater than 6, For the first and second directions orthogonal to each other in the first planar region, when the maximum length of the first magnetic particle passing through the first center of gravity position is defined as the first particle diameter and the second particle diameter, respectively, on a rectangular first band portion centered on the first center of gravity position and having a length five times the first particle diameter on both sides of the first direction and a width equal to the second particle diameter in the second direction, there are 9 to 11 center of gravity positions of the magnetic particles. For the magnetic particles present in the first planar region, when α is taken as the number-based 50% cumulative frequency distribution D50 of the maximum length in the first direction passing through the respective center of gravity positions, the 10% cumulative frequency distribution D10 is greater than or equal to 0.6α and the 90% cumulative frequency distribution D90 is less than or equal to 1.4α. Furthermore, the first particle size of the first magnetic particles is 0.5 μm to 80 μm.

2. A magnetic material consisting of an aggregate of multiple magnetic particles; In a first plane region observed using a scanning electron microscope or an optical microscope so that 50 to 200 magnetic particles fit into one field of view, When the first magnetic particle is rotated 360 / n degrees around the first center of gravity position of the first magnetic particle in the first planar region, the first magnetic particle after rotation overlaps with the first magnetic particle before rotation by more than 90% of its area, wherein Said n is any integer greater than 6, For the first and second directions orthogonal to each other in the first planar region, when the maximum length of the first magnetic particle passing through the first center of gravity position is defined as the first particle diameter and the second particle diameter, respectively, on a rectangular first band portion centered on the first center of gravity position and having a length five times the first particle diameter on both sides of the first direction and a width equal to the second particle diameter in the second direction, there are 9 to 11 center of gravity positions of the magnetic particles. For the magnetic particles present in the first planar region, when α is taken as the number-based 50% cumulative frequency distribution D50 of the maximum length in the first direction passing through the respective center of gravity positions, the 10% cumulative frequency distribution D10 is greater than or equal to 0.6α and the 90% cumulative frequency distribution D90 is less than or equal to 1.4α. Furthermore, in a plurality of n, the first magnetic particles after rotation overlap with the first magnetic particles before rotation by 90% or more in area.

3. The magnetic material according to claim 2, wherein The first particle size of the first magnetic particles is 0.5 μm to 80 μm.

4. The magnetic material according to claim 1 or 2, wherein In the first planar area, for the third direction intersecting the first direction and the fourth direction orthogonal to the third direction, when the maximum length of the first magnetic particle passing through the first center of gravity position is defined as the third particle diameter and the fourth particle diameter, respectively, there are 9 to 11 center of gravity positions on the second band portion of the rectangle centered on the first center of gravity position and having a length of 5 times the third particle diameter on both sides of the third direction and a width equal to the fourth particle diameter in the fourth direction.

5. The magnetic material according to claim 4, wherein The angle formed by the first direction and the third direction is 55 degrees to 65 degrees.

6. The magnetic material according to claim 4, wherein In a second plane region that is not coplanar with the first plane region and is observed using a scanning electron microscope or an optical microscope so that 50 to 200 magnetic particles enter one field of view, When the second magnetic particle is rotated 360 / m degrees around the second center of gravity position of the second magnetic particle in the second planar region, that is, the second center of gravity position, the area of the second magnetic particle after rotation overlaps with the area of the second magnetic particle before rotation by more than 90%, wherein m is any integer greater than 6, With respect to the fifth and sixth directions orthogonal to each other within the second planar region, when the maximum lengths of the second magnetic particles passing through the second center of gravity position are defined as the fifth particle diameter and the sixth particle diameter, respectively, there are 9 to 11 center of gravity positions of the magnetic particles on a third rectangular band portion centered on the second center of gravity position and having a length five times the fifth particle diameter on both sides of the fifth direction and a width equal to the sixth particle diameter in the sixth direction. For the magnetic particles existing in the second plane area, when the 50% cumulative frequency distribution D50 based on the number of the maximum length in the fifth direction passing through each center of gravity position is set to β, the 10% cumulative frequency distribution D10 is greater than 0.6β and the 90% cumulative frequency distribution D90 is less than 1.4β.

7. The magnetic material according to claim 1 or 2, wherein n is 6.

8. The magnetic material according to claim 1 or 2, wherein The surfaces of the magnetic particles are covered with an insulating film.

9. The magnetic material according to claim 8, wherein The insulating film contains at least two elements selected from the group consisting of C, N, O, P, and Si.

10. The magnetic material according to claim 8, wherein The insulating film contains a hydroxyl group or a carbonyl group.

11. The magnetic material according to claim 1 or 2, wherein The magnetic particles contain at least one element selected from the group consisting of Fe, Ni, Co, C, Si, and Cr. 12 . An inductor comprising the magnetic material according to claim 1 .

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