阅读说明：本技术 绝缘体包覆磁性合金粉末颗粒、压粉磁芯及线圈部件 (Insulator-coated magnetic alloy powder particle, dust core, and coil component ) 是由 松本康享 于 2020-10-27 设计创作，主要内容包括：提供一种绝缘体包覆磁性合金粉末颗粒、压粉磁芯及线圈部件,其在不降低导磁率和直流绝缘耐压的前提下,降低高频区域中的颗粒间的涡流损耗。绝缘体包覆磁性合金粉末颗粒(1)的特征在于,包括：磁性合金粉末颗粒(2)；以及绝缘体(7),包覆磁性合金粉末颗粒(2)的表面,且表面具有多个突起(5),绝缘体(7)包括：颗粒状的第一绝缘体(3),包含在突起(5)内；以及膜状的第二绝缘体(4),包覆第一绝缘体(3)的表面的至少一部分。(Provided are an insulator-coated magnetic alloy powder particle, a dust core, and a coil component, which reduce the eddy current loss between particles in a high-frequency region without reducing the magnetic permeability and the DC withstand voltage. Insulator-coated magnetic alloy powder particles (1) characterized by comprising: magnetic alloy powder particles (2); and an insulator (7) that covers the surface of the magnetic alloy powder particles (2) and has a plurality of protrusions (5), the insulator (7) comprising: a granular first insulator (3) contained within the protrusion (5); and a film-like second insulator (4) that covers at least a part of the surface of the first insulator (3).)

1. An insulator-coated magnetic alloy powder particle, comprising:

magnetic alloy powder particles; and

an insulator covering a surface of the magnetic alloy powder particles and having a plurality of protrusions on the surface,

the insulator includes:

a granular first insulator contained within the protrusion; and

and a film-like second insulator covering at least a part of a surface of the first insulator.

2. The insulator-coated magnetic alloy powder particle according to claim 1, wherein the film thickness of the second insulator is 2nm or more and 20nm or less.

3. The insulator-coated magnetic alloy powder particle according to claim 1 or 2, wherein the volume resistivity of the second insulator is 1 x 10¹⁴Omega cm or more and 1X 10¹⁷Omega cm or less.

4. The insulator-coated magnetic alloy powder particle according to claim 1 or 2, wherein the average particle diameter of the first insulator is 4nm or more and 40nm or less.

5. The insulator-coated magnetic alloy powder particle according to claim 1 or 2, wherein the relative permittivity of the first insulator is 2 or more and 4 or less.

6. The insulator-coated magnetic alloy powder particle according to claim 1 or 2, wherein the surface area of the magnetic alloy powder particle is 43nm per 43nm²To 10000nm²Wherein one of the first insulators is present.

7. A powder magnetic core obtained by powder-compressing the magnetic alloy powder particle coated with the insulator according to any one of claims 1 to 6.

8. A coil component comprising the powder magnetic core according to claim 7.

9. A powder magnetic core is characterized in that a powder magnetic core is obtained by powder-compressing magnetic alloy powder particles and an insulator covering the surfaces of the magnetic alloy powder particles,

the insulator includes a granular first insulator and a film-like second insulator,

the second insulator covers at least a portion of a surface of the first insulator,

the dust core includes a void surrounded by the first insulator or the second insulator.

10. A coil component comprising the powder magnetic core according to claim 9.

Technical Field

The invention relates to an insulator-coated magnetic alloy powder particle, a dust core, and a coil component.

Background

Conventionally, magnetic alloy powder particles used for magnetic cores of inductors and the like have been known. In order to suppress eddy currents flowing between the particles, the surfaces of such particles are subjected to an insulating treatment. For example, patent document 1 discloses a magnetic material in which the surfaces of particles of a soft magnetic alloy are coated with an oxide film of the soft magnetic alloy.

Patent document 1: japanese laid-open patent publication No. 2012 and 238828

However, in the magnetic material described in patent document 1, the influence of the displacement current becomes large when used at high frequencies, and it is necessary to increase the value of the capacitive reactance in order to suppress the displacement current. The capacitive reactance Xc is represented by the following formula (1), and the capacitance C in the following formula (1) is represented by the following formula (2).

Xc＝1/2πfC…(1)

C＝Sk/d…(2)

According to the above equations (1) and (2), the capacitance C is decreased to increase the capacitive reactance Xc. In order to reduce the capacitance C, the area S or the dielectric constant k is reduced, or the film thickness d of the insulating treatment film is increased.

In order to improve the performance of an inductor using a magnetic material as a core, there is a method of increasing the magnetic permeability by reducing the film thickness d of an insulating coating film. However, when the film thickness d is reduced, the capacitive reactance Xc is reduced by the above equations (1) and (2), and the eddy current loss between particles when a current flows through the inductor is increased. When the eddy current loss becomes large, the performance as an inductor is degraded. Further, when the film thickness d is increased, the capacitive reactance Xc is increased, while the magnetic permeability is decreased, and the performance as an inductor is also easily decreased. That is, the magnetic permeability and the eddy current loss between particles tend to have an inverse relationship.

In the method of reducing the dielectric constant k without reducing the film thickness d, the dielectric constant k is about 2 even in the case of a material having a small dielectric constant k, and therefore, in order to further reduce the dielectric constant k, a structure in which a hollow wall is provided in the insulating film is considered. However, if an insulating treatment film having a hollow wall is formed in a state where the metal of the magnetic material is exposed, electric charges are induced to the surface of the insulating treatment film when a high voltage is applied, and discharge occurs on the surface of the insulator, causing dielectric breakdown. That is, an object of the present invention is to provide insulator-coated magnetic alloy powder particles that reduce eddy current loss between particles in a high-frequency region without reducing magnetic permeability and dc dielectric breakdown voltage.

Disclosure of Invention

An insulator-coated magnetic alloy powder particle, comprising: magnetic alloy powder particles; and an insulator covering a surface of the magnetic alloy powder particle and having a plurality of protrusions, the insulator including: a granular first insulator contained within the protrusion; and a film-like second insulator covering at least a part of the surface of the first insulator.

In the above insulator-coated magnetic alloy powder particle, the film thickness of the second insulator is preferably 2nm or more and 20nm or less.

In the above insulator-coated magnetic alloy powder particle, the volume resistivity of the second insulator is preferably 1 × 10¹⁴Omega cm or more and 1X 10¹⁷Omega cm or less.

In the above insulator-coated magnetic alloy powder particle, the average particle diameter of the first insulator is preferably 4nm or more and 40nm or less.

In the above insulator-coated magnetic alloy powder particle, the relative permittivity of the first insulator is preferably 2 or more and 4 or less.

In the above insulator-coated magnetic alloy powder particles, the surface area of the magnetic alloy powder particles is preferably 43nm per 43nm²To 10000nm²There is a first insulator.

A powder magnetic core is characterized in that the magnetic core is obtained by powder-compressing magnetic alloy powder particles coated with the insulator.

A coil component is characterized by comprising the powder magnetic core.

A powder magnetic core is obtained by powder-compacting magnetic alloy powder particles and an insulator covering the surfaces of the magnetic alloy powder particles, wherein the insulator includes a granular first insulator and a film-like second insulator, the second insulator covers at least a part of the surface of the first insulator, and the powder magnetic core includes a void surrounded by the first insulator or the second insulator.

A coil component is characterized by comprising the powder magnetic core.

Drawings

Fig. 1 is a schematic cross-sectional view showing one particle of the insulator-coated magnetic alloy powder particles according to the first embodiment.

Fig. 2 is a schematic diagram showing the structure of the dust core.

Fig. 3 is a process flow diagram showing a method for producing the insulator-coated magnetic alloy powder particles.

Fig. 4 is a schematic diagram showing an example of a manufacturing method of the insulator-coated magnetic alloy powder particles.

Fig. 5 is a schematic cross-sectional view showing one particle of the insulator-coated magnetic alloy powder particles according to the second embodiment.

Fig. 6 is an external view of a toroidal coil as a coil component according to a third embodiment.

Fig. 7 is a perspective view of an inductor as a coil component according to a fourth embodiment.

Description of reference numerals:

1. 101 … insulator-coated magnetic alloy powder particles (insulator-coated particles), 2 … magnetic alloy powder particles, 3 … first insulator, 4 … second insulator, 5 … protrusions, 7, 107 … insulators, 9 … voids, 10 … toroidal coil as coil component, 11, 21, 100 … dust core, 20 … inductor as coil component.

Detailed Description

1. First embodiment

The structure of the insulator-coated magnetic alloy powder particles according to the first embodiment will be described. Fig. 1 is a schematic cross-sectional view showing one particle of the insulator-coated magnetic alloy powder particle.

1.1. Insulator coated magnetic alloy powder particles

As shown in fig. 1, the insulator-coated magnetic alloy powder particle 1 of the present embodiment includes a magnetic alloy powder particle 2 and an insulator 7. The insulator 7 covers the surface of the magnetic alloy powder particle 2 and has a plurality of protrusions 5 on the surface. Note that in the following description, the insulator-coated magnetic alloy powder particles 1 are also sometimes simply referred to as insulator-coated particles 1.

1.2. Magnetic alloy powder particles

The magnetic alloy powder particles 2 are particles containing a soft magnetic material. Examples of the soft magnetic material contained in the magnetic alloy powder particles 2 include various Fe-based alloys such as pure iron and silicon steel, Fe-Si-based alloys such as permalloy, Fe-Co-based alloys such as permendur, Fe-Si-Al-based alloys such as sendust, Fe-Cr-Si-based alloys and Fe-Cr-Al-based alloys, various Ni-based alloys, various Co-based alloys, and the like. Among them, various Fe-based alloys are preferably used from the viewpoint of magnetic properties such as magnetic permeability and magnetic flux density, and productivity such as cost.

The crystallinity of the soft magnetic material is not particularly limited, and may be any of crystalline, amorphous (amorphous form), and microcrystalline (nanocrystalline). Among these crystallinities, the soft magnetic material preferably contains an amorphous substance or a microcrystalline substance, and more preferably contains an amorphous substance. This reduces the coercive force of the soft magnetic material, reduces hysteresis loss, improves magnetic permeability and magnetic flux density, and reduces iron loss during powder compaction.

Examples of soft magnetic materials capable of forming an amorphous or microcrystalline material include Fe-Si-B, Fe-Si-B-C, Fe-Si-B-Cr-C, Fe-Si-Cr, Fe-B, Fe-P-C, Fe-Co-Si-B, Fe-Si-B-Nb, Fe-Zr-B Fe-Si-B Fe-B-based Fe-based alloys, Ni-based alloys such as Ni-Si-B and Ni-P-B-based alloys, and Co-based alloys such as Co-Si-B-based alloys. Note that a plurality of soft magnetic materials having different crystallinities may be used for the magnetic alloy powder particles 2.

The soft magnetic material is preferably contained by 50 mass% or more, more preferably 80 mass% or more, and further preferably 90 mass% or more, with respect to the total mass of the magnetic alloy powder particles 2. Thereby, the soft magnetism of the magnetic alloy powder particles 2 is improved.

The magnetic alloy powder particles 2 may contain impurities and additives in addition to the soft magnetic material. Examples of such additives include: various metallic materials, various non-metallic materials, various metal oxide materials, and the like.

The average particle diameter of the magnetic alloy powder particles 2 is not particularly limited, and is, for example, 0.25 μm or more and 250.00 μm or less. Here, the average particle diameter in the present specification means a volume-based particle size distribution (50%). The average particle diameter is measured by a dynamic light scattering method or a laser diffraction method described in JIS Z8825. Specifically, for example, a particle size distribution meter using a dynamic light scattering method as a measurement principle can be used.

The method for producing the magnetic alloy powder particles 2 is not particularly limited, and examples thereof include: various atomization methods such as a water atomization method, a gas atomization method, and a high-speed rotating water stream atomization method, a reduction method, a carbonyl method, a pulverization method, and the like. Among them, from the viewpoint of suppressing variation in particle size and efficiently producing fine particles, the atomization method is preferably used.

1.3. Insulator

The insulator 7 includes a granular first insulator 3 and a film-like second insulator 4. The first insulators 3 are contained in the plurality of protrusions 5, respectively. The second insulator 4 covers at least a part of the surface of the first insulator 3 and a part of the surface of the magnetic alloy powder particles 2. In detail, the second insulator 4 covers the surfaces of the first insulator 3 and the magnetic alloy powder particles 2 except for the region where the first insulator 3 and the magnetic alloy powder particles 2 are in contact with each other.

1.3.1. First insulator

A plurality of first insulators 3 are attached to the surface of the magnetic alloy powder particle 2. The first insulator 3 is granular and smaller than the magnetic alloy powder particles 2. Preferably every 43nm of the surface area of the magnetic alloy powder particles 2²To 10000nm²In the presence of a first insulator 3, more preferably in the above-mentioned surface area per 97nm²To 625nm²There is one first insulator 3.

The average particle diameter of the first insulator 3 is 4nm or more and 40nm or less, and more preferably 6nm or more and 10nm or less. This facilitates formation of the projections 5 in the insulator 7, and voids, which will be described later, are easily generated by the projections 5 when the insulator-coated particles 1 are pulverized. The average particle diameter of the first insulator 3 can be measured in the same manner as the magnetic alloy powder particles 2. Note that the shape of the protrusion 5 can be changed according to the average particle diameter of the first insulator 3 or the like.

The first insulator 3 has a relative dielectric constant of 2 to 4. The relative dielectric constant of the first insulator 3 can be calculated by analyzing the components and based on the components.

The volume resistivity of the first insulator 3 is preferably 1 × 10¹⁴Omega cm or more and 1X 10¹⁷Omega cm or less. This can improve the dc breakdown voltage and the magnetic permeability of the insulator-coated particles 1. The volume resistivity of the first insulator 3 can be measured by a known value or a known measurement method.

Examples of the material for forming the first insulator 3 include: alumina, aluminum fluoride, silica such as crystalline silica and amorphous silica, a fluororesin such as polytetrafluoroethylene, a silicone resin, paraffin, an elastomer such as urethane rubber, and the like. The first insulator 3 uses a single kind or plural kinds of these forming materials.

1.3.2. Second insulator

The second insulator 4 is film-shaped and covers the magnetic alloy powder particles 2 and the first insulator 3. That is, the insulator 7 including the first insulator 3 and the second insulator 4 covers the surface of the magnetic alloy powder particle 2 so that the magnetic alloy powder particle 2 is not exposed on the surface of the insulator-covered particle 1. Therefore, a part of the first insulator 3 may be exposed to the surface of the insulator-coated particle 1 without being coated with the second insulator 4.

The second insulator 4 is raised in a convex shape in a region covering the first insulator 3, and forms a protrusion 5 of the insulator 7. That is, the protrusion 5 exists at a position corresponding to the first insulator 3. Therefore, the number of protrusions 5 in one particle of the insulator-coated particles 1 corresponds to the number of first insulators 3 present on the surface of one particle of the magnetic alloy powder particles 2.

The film thickness of the second insulator 4 is 2nm or more and 20nm or less, and more preferably 3nm or more and 5nm or less. This facilitates formation of the projections 5 in the insulator 7, and voids, which will be described later, are easily generated by the projections 5 when the insulator-coated particles 1 are pulverized. The shape of the projection 5 can be changed according to the film thickness of the second insulator 4, in addition to the average particle diameter of the first insulator 3. The film thickness of the second insulator 4 can be obtained from the average value of the film thicknesses measured at five or more places by observing the cross section of the insulator-coated particle 1 with a transmission electron microscope or the like.

The second insulator 4 has a volume resistivity of 1X 10¹⁴Omega cm or more and 1X 10¹⁷Omega cm or less. This can improve the dc breakdown voltage and the magnetic permeability of the insulator-coated particles 1. As with the first insulator 3, the volume resistivity of the second insulator 4 can be measured by a known value or a known measurement method.

Examples of the material for forming the second insulator 4 include alumina, silicon oxide such as crystalline silicon oxide and amorphous silicon oxide, fluorine resin such as polytetrafluoroethylene, carbon fluoride, polysilazane compound, and silicone resin such as an organic silicon compound. Note that the material for forming the first insulator 3 and the material for forming the second insulator 4 may be the same material, or different materials may be used in combination.

1.4. Dust core

The insulator-coated particles 1 are suitably used for a dust core provided in a coil component such as an inductor or a toroidal coil. The insulator-coated particles 1 are also used for magnetic elements other than coil components, such as antennas and electromagnetic wave absorbers. Therefore, the powder magnetic core is molded into a desired shape in accordance with these uses.

The powder magnetic core 100 according to the present embodiment is manufactured by mixing the insulator-coated particles 1 and the binder or the like into a mixture, and pressure-molding the mixture while heating the mixture. That is, the powder magnetic core 100 is obtained by powder-compressing the insulator-coated particles 1.

Next, the state of the insulator-coated particles 1 inside the powder magnetic core 100 will be described. Fig. 2 is a schematic diagram showing the structure of the dust core. Note that fig. 2 is a diagram schematically illustrating a state of three insulator-coated particles 1 in the powder magnetic core 100. In fig. 2, the first insulator 3 and the bonding material included in the insulator-coated particle 1 are not illustrated.

As shown in fig. 2, the dust core 100 is obtained by compressing insulator-coated particles 1, and the insulator-coated particles 1 include magnetic alloy powder particles 2 and insulators 7 that coat the surfaces of the magnetic alloy powder particles 2. The insulator 7 includes a granular first insulator 3 and a film-like second insulator 4, which are not shown. The second insulator 4 covers at least a part of the first insulator 3.

Here, the surface of the magnetic alloy powder particle 2 is preferably entirely covered with the insulator 7, but there may be a region which is not partially covered with the insulator 7. Even if there are regions that are not coated locally, the chance of the regions matching each other is reduced when the magnetic alloy powder particles 2 are compacted, and therefore a desired effect such as suppression of creeping discharge can be obtained. Note that the entire surface of the coated magnetic alloy powder particle 2 means that a cross section of the insulator-coated particle 1 is observed at five or more places by a transmission electron microscope or the like, and in the observed field of view, no defect such as peeling is detected between the second insulator 4 and the magnetic alloy powder particle 2.

In the dust core 100, the plurality of insulator-coated particles 1 are aggregated and agglomerated by press molding as dust. At this time, the plurality of protrusions 5 provided in each of the insulator-coated particles 1 interfere with each other, and a gap 9 is generated between the insulator-coated particles 1. That is, the dust core 100 includes the void 9 surrounded by the second insulator 4. Note that, as described above, when the first insulator 3 is exposed on the surface of the insulator-coated particle 1, the void 9 surrounded by the first insulator 3 may be included. Since the dielectric constant of air is about 1.00, in the dust core 100, the total dielectric constant is lowered due to the voids 9.

Conventionally, as a method for reducing the dielectric constant by using air, a method of coating a magnetic body with an insulating porous film and using air in the pores, that is, a hollow wall, or a method of attaching insulating particles to a magnetic body and using air between the magnetic bodies have been studied.

In the method using the porous film, when the magnetic bodies are pulverized, the contact between the magnetic bodies is suppressed by the porous film. However, since the surfaces of the magnetic bodies are exposed at the bottoms of the pores of the porous film, when a high voltage is applied, discharge may occur in regions where the pores of adjacent magnetic bodies face each other. In the magnetic material to which the insulator particles are attached, there is a region where the surface of the magnetic material is exposed at a portion to which the insulator particles are not attached. Therefore, when the magnetic bodies are brought close to each other by the dust, discharge may occur in a region where the surfaces of the magnetic bodies are close to each other, as described above. Thus, it has been difficult to improve the insulation resistance with air.

In contrast, in the dust core 100 of the insulator-coated particle 1, the void 9 is formed by interference of the protrusion 5 except for the surface of the magnetic alloy powder particle 2 coated with the insulator 7. Therefore, in the powder magnetic core 100, the dielectric constant between the magnetic alloy powder particles 2 is reduced and the insulation resistance is improved.

When the insulator-coated particles 1 are pulverized, stress acts on the insulator-coated particles 1. In particular, bending stress or the like is applied to the protrusions 5 on the surface of the insulator-coated particle 1. Therefore, when the above-described forming material is used for the second insulator 4, it is preferable that the pressing is performed at a pressure equal to or lower than the bending strength of each forming material. This can suppress the occurrence of breakage of the projection 5, and facilitate formation of the void 9.

The following exemplifies the formation material and the numerical value of the bending strength of the second insulator 4. The numerical value in parentheses of each forming material is the bending strength. Alumina (about 350MPa), quartz (about 150MPa), amorphous silica (about 150MPa), polytetrafluoroethylene (about 600 MPa).

1.5. Method for producing insulator-coated magnetic alloy powder particles

A method for producing the insulator-coated particle 1 will be described. Fig. 3 is a process flow diagram showing a method for producing the insulator-coated magnetic alloy powder particles. Fig. 4 is a schematic diagram showing an example of a manufacturing method of the insulator-coated magnetic alloy powder particles.

As shown in fig. 3, the method for producing the insulator-coated particle 1 according to the present embodiment includes steps S1 to S3. Note that the process flow shown in fig. 3 is only an example, and is not limited thereto.

In step S1, the magnetic alloy powder particles 2 are pretreated. Specifically, the surface of the magnetic alloy powder particle 2 is treated to remove the adhering substances such as organic substances and to improve the wettability of the surface. Examples of the pretreatment include ozone treatment and plasma treatment. Specifically, in the ozone treatment, the magnetic alloy powder particles 2 are exposed for 10 minutes or longer in an atmosphere having an ozone concentration of 5000 ppm.

In the plasma treatment, He (helium), Ar (argon), N (nitrogen) is used for atmospheric pressure plasma or vacuum plasma₂(Nitrogen), H₂O (water), O₂And a gas such as (oxygen) or Ne (neon). In this case, it is preferable not to use F₂(fluorine) and Cl₂A gas such as (chlorine) remaining on or etching the surface of the magnetic alloy powder particles 2.

The surface wettability index of the magnetic alloy powder particles 2 uses the contact angle of water. The contact angle of water on the surface of the magnetic alloy powder particles 2 after the pretreatment in step S1 is 15 ° or less. This improves the adhesion of the first insulator 3 and the second insulator 4 to the magnetic alloy powder particles 2. Then, the process proceeds to step S2.

In step S2, the first granular insulator 3 is formed on the surface of the magnetic alloy powder particle 2. Specifically, for example, as shown in fig. 4, magnetic alloy powder particles 2 are put into a cylindrical container 30, and particles of the material for forming the first insulator 3 are put into the container while rotating the inclined cylindrical container 30. By this operation, the first insulator 3 is attached to the surface of the magnetic alloy powder particle 2 by electrostatic interaction or the like.

The average particle diameter of the material for forming the first insulator 3 put into the cylindrical container 30 is the average particle diameter of the first insulator 3. The number of first insulators 3 attached to the surface of magnetic alloy powder particle 2 is within a numerical range with respect to the surface area of magnetic alloy powder particle 2. Then, the process proceeds to step S3.

In step S3, second insulator 4 and protrusion 5 are formed on magnetic alloy powder particle 2 to which first insulator 3 is attached. Examples of the method for forming the second insulator 4 and the protrusion 5 include an ALD (Atomic Layer Deposition), a sol-gel method, a dipping method, a thermal oxidation method, a CVD (Chemical Vapor Deposition) method, and a direct coating method.

When the ALD method is employed, for example, a silicon-containing compound such as trisdimethylaminosilane is used in order to form silicon oxide as the second insulator 4. The silicon-containing compound used was the following: an alkyl group or an amino group having an alkyl group which is easily reacted with a hydroxyl group by heat. First, the magnetic alloy powder particles 2 to which the first insulator 3 is attached are thermally reacted with the silicon-containing compound. The surface is then oxidized with ozone, water or oxygen plasma. Then, the reaction of the silicon-containing compound is repeated again until the film thickness of the second insulator 4 is obtained.

When the sol-gel method is employed, for example, in order to form silicon oxide as the second insulator 4, a silicon compound having two to four alkoxy groups in a molecule such as tetraethyl orthosilicate is used.

First, the silicon compound, water used for the reaction, and ammonia as a catalyst were added to ethanol to prepare a mixed solution. Next, the magnetic alloy powder particles 2 to which the first insulator 3 is attached are put into the mixed solution, and the hydrolysis and polycondensation reaction of the alkoxy group in the silicon compound forms the second insulator 4 to cover the magnetic alloy powder particles 2 and the first insulator 3. At this time, the protrusion 5 is also formed.

When a plasma CVD method is employed among CVD methods, for example, a silicon compound in which hydrogen, an alkyl group, or an alkoxy group is added to a silicon atom is used to form silicon oxide as the second insulator 4. The silicon compound is introduced into the apparatus for oxidizing the magnetic alloy powder particles 2 to which the first insulator 3 is attached by oxygen plasma, thereby forming the second insulator 4 and the protrusion 5. Alternatively, organosilane may be introduced into the apparatus for the magnetic alloy powder particles 2 to which the first insulator 3 is attached, and polymerization may be caused by argon plasma to form the second insulator 4 and the protrusion 5.

In order to form carbon fluoride as the second insulator 4, for example, perfluorocarbon is introduced into the apparatus for the magnetic alloy powder particles 2 to which the first insulator 3 is attached, and the second insulator 4 and the projections 5 are formed by argon plasma.

As another method for producing the insulator-coated particles 1, there is a method in which powder particles as a material for forming the first insulator 3 and the second insulator 4 are sprinkled on the magnetic alloy powder particles 2. Specifically, the cylindrical container 30 of step S2 shown in fig. 4 is used to sprinkle the magnetic alloy powder particles 2 to which the first insulator 3 has adhered, with the powder of the material for forming the second insulator 4 while rotating the cylindrical container 30. The powder is intermittently charged. At this time, the inside of the cylindrical container 30 may be heated. Thereby, the protrusion 5 and the second insulator 4 are formed, and the insulator-coated particle 1 is manufactured.

Further, the first insulator 3, the second insulator 4, and the projection 5 may be formed continuously by performing the above-described operation on the magnetic alloy powder particles 2 to which the first insulator 3 is not attached. In this case, the first insulator 3 and the second insulator 4 contain the same forming material.

According to the present embodiment, the following effects can be obtained.

The eddy current loss between particles in a high-frequency region can be reduced without reducing the magnetic permeability and the DC dielectric breakdown voltage. In detail, the surface of the magnetic alloy powder particle 2 is coated with the insulator 7. In addition, during the powder compaction, the plurality of protrusions 5 provided between the insulator-coated particles 1 interfere with each other, and the insulator-coated particles 1 are not easily brought into close contact with each other. Therefore, the voids 9 surrounded by the insulator 7 are generated, and the voids 9 function as another insulator, so that the eddy current loss between particles can be reduced. Further, since the surfaces of the magnetic alloy powder particles 2 are coated with the insulator 7, even if the high voltage is applied after the powder compaction, creeping discharge along the interface between the gap 9 and the insulator 7 is less likely to occur between the insulator-coated particles 1, and the dc dielectric breakdown voltage can be ensured without increasing the film thickness in the insulator 7, particularly without increasing the film thickness of the second insulator 4.

Since the granular first insulator 3 is contained in the insulator 7, the plurality of protrusions 5 of the insulator 7 can be easily formed with the first insulator 3 as a core.

Since the second insulator 4 has a film thickness of 2nm or more, generation of creeping discharge is further suppressed, and the dc dielectric breakdown voltage can be improved. Since the second insulator 4 has a film thickness of 20nm or less, the magnetic permeability can be improved.

Since the volume resistivity of the second insulator 4 is 1 × 10¹⁴Since Ω · cm or more, generation of creeping discharge is further suppressed, and the dc withstand voltage can be improved. Since the volume resistivity of the second insulator 4 is 1 × 10¹⁷Since the magnetic permeability is not more than Ω · cm, the magnetic permeability can be improved.

Since the average particle diameter of the first insulator 3 is 4nm or more, the volume of the protrusion 5 of the insulator 7 increases. Therefore, at the time of powder compaction, the protrusions 5 of the insulator 7 more easily interfere with each other between the insulator-coated particles 1, and a void 9 surrounded by the insulator 7 is generated. The voids 9 function as another insulator, and can further reduce eddy current loss between the insulator-coated particles 1.

Since the average particle diameter of the first insulator 3 is 40nm or less, the volume of the protrusion 5 of the insulator 7 does not increase extremely. Therefore, the insulator-coated particles 1 are not excessively separated from each other at the time of powder compaction. Therefore, the ratio of the insulator 7 and the voids 9 to the magnetic alloy powder particles 2 is not easily increased, and a decrease in magnetic permeability can be suppressed.

Since the relative dielectric constant of the first insulator 3 is 2 or more and 4 or less, the total dielectric constant among the magnetic alloy powder particles 2 is reduced together with the voids 9 formed by the protrusions 5. Therefore, the eddy current loss can be reduced.

Since the surface area of the magnetic alloy powder particles 2 is 43nm per²To 10000nm²Since there is one first insulator 3, the space 9 surrounded by the insulator 7 can be easily generated by the protrusion 5 at the time of powder pressing. In detail, the surface area of the magnetic alloy powder particles 2 due to the presence of one first insulator 3 is 43nm²As described above, the plurality of protrusions 5 are not excessively dense, and the voids 9 are easily generated. In addition, since the surface area is 10000nm²Hereinafter, the plurality of protrusions 5 are not excessively thinned. Therefore, the voids 9 are easily generated, and the protrusions 5 are not easily crushed at the time of powder compaction.

Since the dust core 100 is obtained by compressing the above-described insulator-coated particles 1, the eddy current loss between the insulator-coated particles 1 in the high-frequency region can be reduced without lowering the magnetic permeability and the dc withstand voltage.

2. Second embodiment

2.1. Insulator coated magnetic alloy powder particles

The structure of the insulator-coated magnetic alloy powder particles according to the second embodiment will be explained. Fig. 5 is a schematic cross-sectional view showing one particle of the insulator-coated magnetic alloy powder particles according to the second embodiment. Note that the insulator-coated magnetic alloy powder particles of the present embodiment differ in the constitution of the insulator from the insulator-coated particles 1 of the first embodiment. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant description thereof is omitted.

As shown in fig. 5, the insulator-coated magnetic alloy powder particles 101 of the present embodiment include magnetic alloy powder particles 2 and an insulator 107. The insulator 107 covers the surface of the magnetic alloy powder particle 2, and the surface has a plurality of protrusions 5. Note that in the following description, the insulator-coated magnetic alloy powder particles 101 may be simply referred to as insulator-coated particles 101.

2.2. Insulator

The insulator 107 includes a film-like third insulator 6, a granular first insulator 3, and a film-like second insulator 4. That is, the insulator-coated particle 101 is different from the insulator of the first embodiment in that it includes the third insulator 6.

The third insulator 6 covers the magnetic alloy powder particles 2, and is disposed between the magnetic alloy powder particles 2 and the first insulator 3 and the second insulator 4. The first insulators 3 are contained in the plurality of protrusions 5, respectively. The second insulator 4 covers at least a part of the surface of the first insulator 3 and a part of the surface of the third insulator 6. Specifically, the second insulator 4 covers the surfaces of the first insulator 3 and the third insulator 6 except for the region where the first insulator 3 and the third insulator 6 contact each other.

2.2.1. Third insulator

The third insulator 6 is in the form of a film and covers the magnetic alloy powder particles 2. That is, the insulator 107 including the third insulator 6, the first insulator 3, and the second insulator 4 covers the surface of the magnetic alloy powder particle 2 so that the magnetic alloy powder particle 2 is not exposed to the surface of the insulator-covered particle 101. Therefore, a part of the first insulator 3 may be exposed to the surface of the insulator-coated particle 101 without being coated with the second insulator 4.

The film thickness of the third insulator 6 is 2nm or more and 20nm or less, and more preferably 3nm or more and 5nm or less. It can be seen that the film thickness of the third insulator 6 is the same as the film thickness of the second insulator 4 of the insulator-coated particle 1. In addition, the volume resistivity of the third insulator 6 is 1 × 10¹⁴Omega cm or more and 1X 10¹⁷Omega cm or less. This can improve the dc breakdown voltage and the magnetic permeability of the insulator-coated particles 101. The volume resistivity of the third insulator 6 can be measured by a known value or a known measurement method, as in the case of the first insulator 3. Note that the third insulator 6 may be formed using the same material and method as those of the second insulator 4.

According to the present embodiment, the following effects can be obtained in addition to the effects of the first embodiment.

Since the magnetic alloy powder particles 2 are coated with the third insulator 6 in addition to the second insulator 4, the magnetic alloy powder particles 2 are less likely to be exposed to the surface of the insulator-coated particles 101. Therefore, even if the powder compaction is performed and a high voltage is applied, creeping discharge is less likely to occur between the insulator-coated particles 101, and the eddy current loss can be further reduced.

3. Third embodiment

A toroidal coil is exemplified as the coil component according to the third embodiment. Fig. 6 is an external view of a toroidal coil as a coil component according to a third embodiment.

As shown in fig. 6, the toroidal coil 10 of the present embodiment includes an annular dust core 11 and a lead wire 12 wound around the dust core 11. The dust core 11 is a dust core obtained by annularly molding the dust core 100 of the first embodiment.

The powder magnetic core 11 is manufactured by mixing the insulator-coated particles 1 of the first embodiment with a binder to form a mixture, and press-molding the mixture. Examples of the binder include organic materials such as silicone resins, epoxy resins, phenol resins, polyamide resins, polyimide resins, and polyphenylene sulfide resins, inorganic materials such as phosphates such as magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, and cadmium phosphate, and silicates such as sodium silicate. Note that the bonding material is not essential, and the powder magnetic core 11 may be manufactured without using the bonding material.

The material for forming the lead 12 is not particularly limited as long as it is a material having high conductivity, and examples thereof include metal materials including Cu (copper), Al (aluminum), Ag (silver), Au (gold), Ni (nickel), and the like.

Although not shown, a surface layer having insulation properties is provided on the surface of the lead 12. By the surface layer, short circuit between the dust core 11 and the wire 12 is prevented. The material for forming the surface layer may be a known resin having insulating properties.

The shape of the powder magnetic core 11 is not limited to a ring shape, and may be, for example, a shape in which a part of the ring is missing, a rod shape, or the like.

The powder magnetic core 11 may include magnetic alloy powder particles or non-magnetic alloy powder particles other than the insulator-coated particles 1 of the above-described embodiment, as necessary. When they are included, the mixing ratio of these powder particles and the insulator-coated particles 1 is not particularly limited and may be arbitrarily set. In addition, a plurality of kinds of the above powder particles other than the insulator-coated particles 1 may also be used.

In the present embodiment, the toroidal coil 10 is exemplified as the coil component, but the present invention is not limited thereto. Examples of the coil component to which the insulator-coated particles 1 are applied include, in addition to a toroidal coil, an inductor, a reactor, a transformer, a motor, a generator, and the like. These coil components may include a dust core obtained by powdering the insulator-coated particles 101 according to the second embodiment, instead of the dust core 100.

The dust core 100 can also be used for magnetic elements other than coil components such as antennas and electromagnetic wave absorbers.

According to the present embodiment, the following effects can be obtained.

The annular coil 10 can be formed, and eddy current loss between particles in a high-frequency region is reduced and performance is improved without reducing magnetic permeability and direct-current insulation withstand voltage.

4. Fourth embodiment

An inductor is exemplified as the coil component according to the fourth embodiment. Fig. 7 is a perspective view of an inductor as a coil component according to a fourth embodiment.

As shown in fig. 7, the inductor 20 of the present embodiment includes a dust core 21 formed by forming the dust core 100 of the first embodiment into a substantially rectangular parallelepiped shape. In the inductor 20, a wire 22 formed in a coil shape is embedded inside the dust core 21. That is, the inductor 20 is formed in such a manner that the conductive wire 22 is molded by the dust core 21.

Since the lead wire 22 is embedded inside the powder magnetic core 21, a gap is less likely to be generated between the lead wire 22 and the powder magnetic core 21. Therefore, vibration due to magnetostriction of the dust core 21 can be suppressed, and generation of noise due to vibration can be suppressed. Further, since the lead wire 22 is embedded in the dust core 21 and molded, the inductor 20 can be easily downsized.

The configuration of the dust core 21 is the same as that of the dust core 11 of the above-described embodiment, except for the difference in shape. The dust core 21 may use the insulator-coated particles 101 of the second embodiment instead of the insulator-coated particles 1 of the first embodiment. The configuration of the lead 22 is the same as that of the lead 12 of the above embodiment, except that the shape of the formation is different.

According to the present embodiment, the following effects can be obtained.

The inductor 20 can be formed to reduce the eddy current loss between particles in the high frequency region without reducing the magnetic permeability and the dc dielectric breakdown voltage, thereby improving the performance.

5. Modification example

The coil component using the powder magnetic core 100 of the above embodiment can be applied to various electronic devices. Examples of the various electronic devices include: notebook or portable personal computers, mobile phones, digital still cameras, smartphones, tablet terminals, watches including smartwatches, smartglasses, wearable terminals such as HMDs (head mounted displays), televisions, video cameras, video tape recorders, car navigation systems, pagers, electronic notebooks with communication functions, electronic dictionaries, calculators, electronic game devices, word processors, workstations, videophones, security television monitors, electronic binoculars, pos (point Of sale) system terminals, medical devices such as electronic thermometers, sphygmomanometers, blood glucose meters, electrocardiograph measuring devices, ultrasonic diagnostic devices, electronic endoscopes, fish school detectors, various measuring devices, meters mounted on vehicles, airplanes, ships, etc., base stations for mobile terminals, flight simulators, and the like. By using the coil component of the above-described embodiment in these electronic devices, the performance is improved, and the coil component can be easily applied to miniaturization and high frequency.

The coil component using the powder magnetic core 100 of the above embodiment can be applied to various devices provided in various moving bodies. Examples of such various devices include: keyless entry, anti-theft device, car navigation system, car air conditioning control system, ABS (antilock brake) system, airbag, TPMS (tire pressure monitoring system), engine control system, brake system, battery monitor of hybrid car or electric car, body posture control system, electronic control unit such as automatic driving system, and the like. By providing the coil component of the above embodiment, various devices provided in these mobile bodies have improved performance and are easily adaptable to miniaturization and high frequency.

The following describes the contents derived from the embodiments.

An insulator-coated magnetic alloy powder particle, comprising: magnetic alloy powder particles and an insulator, the insulator covering a surface of the magnetic alloy powder particles and having a plurality of protrusions on the surface, the insulator comprising: a granular first insulator contained within the protrusion; and a film-like second insulator covering at least a part of the surface of the first insulator.

According to this configuration, the eddy current loss between particles in the high-frequency region can be reduced without reducing the magnetic permeability and the dc dielectric breakdown voltage. In detail, the surface of the magnetic alloy powder particle is coated with an insulator. Further, the plurality of protrusions provided between the insulator-coated magnetic alloy powder particles interfere with each other, and the insulator-coated magnetic alloy powder particles are less likely to come into close contact with each other during powder compaction. Therefore, voids surrounded by the insulator are generated, and the voids function as another insulator, so that the eddy current loss between particles can be reduced. Further, since the surfaces of the magnetic alloy powder particles are coated with the insulator, even when the powder is compacted and a high voltage is applied, creeping discharge along the interface between the gap and the insulator is less likely to occur between the insulator-coated magnetic alloy powder particles, and the dc dielectric breakdown voltage can be secured without increasing the thickness of the insulator, particularly the second insulator.

Since the granular first insulator is contained in the insulator, the plurality of projections of the insulator can be easily formed with the first insulator as a core.

In the above insulator-coated magnetic alloy powder particle, the film thickness of the second insulator is preferably 2nm or more and 20nm or less.

According to this configuration, since the second insulator has a film thickness of 2nm or more, generation of creeping discharge is further suppressed, and the dc withstand voltage can be improved. Since the second insulator has a film thickness of 20nm or less, the magnetic permeability can be improved.

In the above insulator-coated magnetic alloy powder particle, the volume resistivity of the second insulator is preferably 1 × 10¹⁴Omega cm or more and 1X 10¹⁷Omega cm or less.

According to this constitution, since the volume resistivity of the second insulator is 1 × 10¹⁴Since the voltage is not less than Ω · cm, generation of creeping discharge is further suppressed, and the dc withstand voltage can be improved. Since the volume resistivity of the second insulator is 1 × 10¹⁷Since the magnetic permeability is not more than Ω · cm, the magnetic permeability can be improved.

In the above insulator-coated magnetic alloy powder particle, the average particle diameter of the first insulator is preferably 4nm or more and 40nm or less.

According to this configuration, since the average particle diameter of the first insulator is 4nm or more, the volume of the protrusion of the insulator increases. Therefore, at the time of powder compaction, between the insulator-coated magnetic alloy powder particles, the projections of the insulator more easily interfere with each other, and a void surrounded by the insulator is generated. The voids function as additional insulators, and eddy current loss between the insulator-coated magnetic alloy powder particles can be further reduced.

Since the average particle diameter of the first insulator is 40nm or less, the volume of the protrusion of the insulator does not increase extremely. Therefore, the insulator-coated magnetic alloy powder particles are not excessively separated from each other at the time of powder compaction. Therefore, the ratio of the insulator to the voids to the magnetic alloy powder particles is not easily increased, and a decrease in magnetic permeability can be suppressed.

In the above insulator-coated magnetic alloy powder particle, the relative permittivity of the first insulator is preferably 2 or more and 4 or less.

According to this configuration, the total dielectric constant between the magnetic alloy powder particles is reduced together with the voids formed by the protrusions. Therefore, the eddy current loss can be reduced.

In the above insulator-coated magnetic alloy powder particles, the surface area of the magnetic alloy powder particles is preferably 43nm per 43nm²To 10000nm²There is a first insulator.

According to this configuration, a void surrounded by the insulator through the protrusion can be easily generated at the time of powder compaction. In detail, the surface area of the magnetic alloy powder particles due to the presence of one first insulator was 43nm²Thus, the plurality of protrusions are not too dense, and voids are likely to be generated. In addition, since the surface area is 10000nm²Hereinafter, the plurality of protrusions are not excessively sparse. Therefore, voids are easily generated, and the protrusions are not easily crushed at the time of powder compaction.

A powder magnetic core is characterized in that the magnetic core is obtained by powder-compressing magnetic alloy powder particles coated with the insulator.

According to this configuration, a powder magnetic core can be formed, and eddy current loss between particles in a high-frequency region can be reduced without reducing magnetic permeability and a dc dielectric breakdown voltage.

A coil component is characterized by comprising the powder magnetic core.

According to this configuration, a coil component can be formed in which eddy current loss between particles in a high-frequency region is reduced and performance is improved without lowering magnetic permeability and dc dielectric breakdown voltage.

A powder magnetic core is a powder magnetic core formed by powder-compressing magnetic alloy powder particles and an insulator covering the surfaces of the magnetic alloy powder particles, wherein the insulator includes: the powder magnetic core includes a granular first insulator and a film-like second insulator covering at least a part of a surface of the first insulator, and the powder magnetic core includes a void surrounded by the first insulator or the second insulator.

According to this configuration, the eddy current loss between particles in the high-frequency region can be reduced without reducing the magnetic permeability and the dc dielectric breakdown voltage. In detail, since the gap surrounded by the first insulator or the second insulator functions as a separate insulator, creeping discharge is less likely to occur between the insulator-coated magnetic alloy powder particles even when high voltage is applied by compacting the powder, and eddy current loss can be reduced. That is, the dc dielectric breakdown voltage can be ensured without increasing the film thickness of the insulator, particularly the second insulator.

Since the dc breakdown voltage does not have a high dependency on the film thickness of the second insulator, the film thickness of the second insulator can be set to be thin, and magnetic permeability can be ensured. Thus, a powder magnetic core can be provided, in which eddy current loss between particles in a high-frequency region is reduced without reducing magnetic permeability and DC withstand voltage.

A coil component is characterized by comprising the powder magnetic core.

According to this configuration, a coil component can be formed in which eddy current loss between particles in a high-frequency region is reduced and performance is improved without lowering magnetic permeability and dc dielectric breakdown voltage.