Soft magnetic powder, pressed powder core, magnetic components, electronic equipment and moving objects

Abstract

The present invention provides soft magnetic powder, pressed powder core, magnetic element, electronic device and moving body, which can manufacture pressed powder with good filling property and low eddy current loss when used in high frequency band. A soft magnetic powder, characterized in that the volume-based particle size distribution is measured by a laser diffraction scattering particle size distribution measuring device, the particle size distribution is plotted in an orthogonal coordinate system with the horizontal axis being the particle size and the vertical axis being the relative particle amount, and a particle size distribution curve is drawn, at which time, the particle size distribution curve has: a first peak with a maximum value at a particle size D1 [μm], and a second peak with a maximum value at a particle size D2 [μm] larger than the particle size D1, the particle size D1 is within the range of 1.0 μm or more and 16.0 μm or less, and the difference D2-D1 between the particle size D1 and the particle size D2 satisfies the formula D2-D1=k1×D1 and the formula 1.0≤k1≤15.0.

Description

Technical Field

[0001] The present invention relates to soft magnetic powder, a pressed powder magnetic core, a magnetic element, an electronic device and a moving body. Background Art

[0002] Patent document 1 discloses a soft magnetic solid material obtained by compressing and solidifying a soft magnetic powder having an insulating coating. From the viewpoint of the filling rate of the powder, a double-peak powder mixed system having two particle size peaks is used as the soft magnetic powder. Thus, the high density of the soft magnetic solid material can be achieved. In addition, by achieving high density, the magnetic permeability of the soft magnetic solid material can be improved.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2003-234206

[0004] However, Patent Document 1 does not clearly indicate how to set two particle size peaks in a bimodal powder mixture system. The particle size peak affects the filling property and the core loss. Therefore, it is necessary to optimize the two particle size peaks. Summary of the invention

[0005] The soft magnetic powder according to the application example of the present invention is characterized in that:

[0006] The volume-based particle size distribution is measured by a laser diffraction scattering particle size distribution measuring device, and the particle size distribution is plotted in an orthogonal coordinate system in which the horizontal axis is the particle diameter and the vertical axis is the relative particle amount to draw a particle size distribution curve. At this time,

[0007] The particle size distribution curve has a first peak having a local maximum at a particle size D1 [μm] and a second peak having a local maximum at a particle size D2 [μm] larger than the particle size D1.

[0008] The particle size D1 is within a range of 1.0 μm or more and 16.0 μm or less.

[0009] The difference D2-D1 between the particle diameter D1 and the particle diameter D2 satisfies the following formula (A-1) and the following formula (A-2):

[0010] D2-D1=k1×D1…(A-1),

[0011] 1.0≤k1≤15.0…(A-2).

[0012] A powder magnetic core according to an application example of the present invention is characterized in that:

[0013] The soft magnetic powder according to the application example of the present invention is contained.

[0014] A magnetic element according to an application example of the present invention is characterized in that:

[0015] A powder magnetic core according to an application example of the present invention is provided.

[0016] An electronic device according to an application example of the present invention is characterized in that:

[0017] A magnetic element according to an application example of the present invention is provided.

[0018] A moving object according to an application example of the present invention is characterized in that:

[0019] A magnetic element according to an application example of the present invention is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram showing an example of a particle size distribution curve PSD obtained for the soft magnetic powder according to the embodiment.

[0021] Figure 2 It is a top view schematically showing a toroidal coil component.

[0022] Figure 3 It is a perspective view schematically showing a closed magnetic circuit type coil component.

[0023] Figure 4 It is a perspective view showing a mobile personal computer as an electronic device including the magnetic element according to the embodiment.

[0024] Figure 5 It is a top view showing a smartphone as an electronic device including the magnetic element according to the embodiment.

[0025] Figure 6 It is a perspective view showing a digital still camera as an electronic device including a magnetic element according to the embodiment.

[0026] Figure 7 It is a perspective view showing a car as a moving object including the magnetic element according to the embodiment.

[0027] Figure 8 This is a graph showing the particle size distribution curves obtained for the soft magnetic powders of Examples 1 to 5 in an overlapping manner.

[0028] Fig. 9 This is a graph showing the particle size distribution curves obtained for the soft magnetic powders of Examples 6 to 9 and Comparative Example 2 in a superimposed manner.

[0029] Fig.10 This is a graph showing the particle size distribution curves obtained for the soft magnetic powders of Examples 10 to 14 in a superimposed manner.

[0030] Description of Reference Numerals

[0031] 10: coil component; 11: pressed powder core; 12: wire; 20: coil component; 21: pressed powder core; 22: wire; 100: display unit; 1000: magnetic element; 1100: personal computer; 1102: keyboard; 1104: main body; 1106: display unit; 1200: smart phone; 1202: operation button; 1204: answering port; 1206: talking port; 1300: still digital camera; 1302: housing; 1304: light receiving unit; 1306: shutter button; 1308: memory; 1500: automobile; B: bottom; H1: height; H2: height; H3: height; P1: first peak; P2: second peak; PSD: particle size distribution curve. DETAILED DESCRIPTION

[0032] Hereinafter, the soft magnetic powder, the powder magnetic core, the magnetic element, the electronic device, and the moving body of the present invention will be described in detail based on the drawings.

[0033] 1. Soft magnetic powder

[0034] First, the soft magnetic powder according to the embodiment will be described.

[0035] The soft magnetic powder according to the embodiment contains soft magnetic particles and has a particle size distribution curve having a bimodal distribution (bimodal distribution) with two peaks.

[0036] Specifically, first, in the soft magnetic powder involved in the embodiment, when the volume-based particle size distribution is measured by a laser diffraction scattering particle size distribution measuring device, the obtained particle size distribution curve PSD has the following characteristics. The particle size distribution curve PSD is a curve that can be drawn when the measured particle size distribution is plotted in an orthogonal coordinate system in which the horizontal axis is the particle diameter and the vertical axis is the relative particle amount. It should be noted that as a laser diffraction scattering particle size distribution measuring device, for example, MICROTRAC and HRA9320-X100 manufactured by Nikkiso Co., Ltd. can be cited.

[0037] Figure 1 This is a diagram showing an example of a particle size distribution curve PSD obtained for the soft magnetic powder according to the embodiment.

[0038] Figure 1 The particle size distribution curve PSD shown is a curve having a first peak P1 having a maximum value at a particle size D1 [μm] and a second peak P2 having a maximum value at a particle size D2 [μm] larger than the particle size D1. The particle size D1 is within the range of 1.0 μm or more and 16.0 μm or less. In addition, the difference D2-D1 between the particle size D1 and the particle size D2 satisfies the following formula (A-1) and the following formula (A-2):

[0039] D2-D1=k1×D1…(A-1),

[0040] 1.0≤k1≤15.0…(A-2).

[0041] In such a soft magnetic powder, the bimodal characteristics are optimized, so the particle size balance of large diameter particles and small diameter particles is good, and the overall diameter is small. Therefore, the soft magnetic powder involved in the embodiment becomes a powder that can produce a compressed powder body with good filling properties and low eddy current loss when used in a high frequency band. As a result, a compressed powder body with good magnetic properties such as magnetic permeability and magnetic flux density and low core loss can be achieved. Examples of the compressed powder body include a compressed powder core, a compressed powder magnetic sheet, a compressed powder magnetic film, etc.

[0042] As described above, the first peak P1 has a local maximum at the particle diameter D1 [μm]. The particle diameter D1 is within a range of 1.0 μm to 16.0 μm, preferably 1.0 μm to 10.0 μm, and more preferably 1.0 μm to 8.0 μm.

[0043] It should be noted that when the particle size D1 is below the lower limit, the filling property of the soft magnetic powder is reduced and the magnetic properties of the powder compact are reduced. On the other hand, when the particle size D1 exceeds the upper limit, the eddy current loss within the particles in the powder compact increases when used in a high frequency band.

[0044] As described above, the second peak P2 has a local maximum at the particle size D2 [μm]. In addition, the coefficient k1 included in the above formula (A-1) satisfies the above formula (A-2), preferably satisfies the following formula (A-3), and more preferably satisfies the following formula (A-4).

[0045] 2.0≤k1≤14.0…(A-3)

[0046] 4.0≤k1≤12.0…(A-4)

[0047] It should be noted that when the coefficient k1 is lower than the lower limit, the first peak P1 and the second peak P2 are close to each other. Therefore, the balance between large-diameter particles and small-diameter particles is destroyed, and the filling property of the soft magnetic powder is reduced. On the other hand, when the coefficient k1 exceeds the upper limit, the first peak P1 and the second peak P2 are separated from each other. Therefore, the balance between large-diameter particles and small-diameter particles is destroyed, and the filling property of the soft magnetic powder is reduced. In addition, the particle size D2 is too large, and when used in a high-frequency band, the eddy current loss within the particles in the powder compact is easily increased.

[0048] The particle size D2 is preferably within a range of 15.0 μm to 50.0 μm, more preferably 25.0 μm to 45.0 μm, and even more preferably 28.0 μm to 40.0 μm.

[0049] By making the particle size D2 within the above range, the particle size balance between large-diameter particles and small-diameter particles can be further improved, and the overall particle size can be prevented from becoming too large. As a result, a soft magnetic powder that can improve the magnetic properties of the powder compact and reduce the core loss can be obtained.

[0050] The soft magnetic material constituting the soft magnetic powder may be one kind or a mixture of two or more kinds. That is, since the soft magnetic powder is an aggregate of a plurality of soft magnetic particles, a mixed powder having particles consisting of a first soft magnetic material and particles consisting of a second soft magnetic material having an alloy composition different from that of the first soft magnetic material may be used. According to the mixed powder of two or more kinds of particles having different alloy compositions, a soft magnetic powder having magnetic properties derived from both the first soft magnetic material and the second soft magnetic material may be obtained. Therefore, for example, a powder compact having particularly high magnetic properties may be obtained.

[0051] Soft magnetic powder is based on soft magnetic material. As soft magnetic material, for example, various Fe alloys such as Fe-Si alloys such as pure iron, silicon steel, Fe-Ni alloys such as permalloy, Fe-Co alloys such as permalloy, sandast alloy, Fe-Si-Al alloys, Fe-Cr-Si alloys, Fe-Cr-Al alloys, and various Ni alloys, various Co alloys, etc. can be listed. Wherein, from the viewpoints of magnetic properties such as magnetic permeability, magnetic flux density and cost, various Fe alloys are preferably used.

[0052] The crystal structure of the soft magnetic material is not particularly limited, and may be crystalline, amorphous (amorphous), or microcrystalline (nanocrystalline).

[0053] Crystalline soft magnetic materials are relatively cheap, so they help to reduce the cost of soft magnetic powders. Amorphous soft magnetic materials tend to have higher magnetic permeability and lower coercivity than crystalline soft magnetic materials, so they help to improve the magnetic properties of the powder compact and reduce core loss. Microcrystalline soft magnetic materials tend to have higher magnetic permeability and saturation magnetic flux density than amorphous soft magnetic materials, so they help to further improve the magnetic properties of the powder compact.

[0054] Therefore, the soft magnetic powder preferably contains two or more types of particles having different crystal structures. This can realize a soft magnetic powder having two or more properties that are different depending on the crystal structure.

[0055] The soft magnetic powder preferably contains an amorphous soft magnetic material or a microcrystalline soft magnetic material. By containing these components, the magnetic properties of the soft magnetic powder can be improved and low coercivity can be achieved. As a result, a powder compact having particularly high magnetic properties and further low core loss can be achieved.

[0056] The soft magnetic powder may be a mixture of a powder mainly made of an amorphous soft magnetic material and a powder mainly made of a microcrystalline soft magnetic material, thereby achieving a soft magnetic powder having the characteristics of both powders.

[0057] The microcrystalline soft magnetic material refers to a soft magnetic material containing crystal grains with a grain size of 1.0 nm or more and 30.0 nm or less. In the microcrystalline soft magnetic material, the volume ratio of the crystal grains is preferably 30% by volume or more, more preferably 40% by volume or more.

[0058] As amorphous soft magnetic materials and microcrystalline soft magnetic materials, for example, Fe-Si-B series, Fe-Si-BC series, Fe-Si-B-Cr-C series, Fe-Si-Cr series, Fe-B series, Fe-PC series, Fe-Co-Si-B series, Fe-Si-B-Nb series, Fe-Si-B-Nb-Cu series, Fe-Zr-B series and other Fe series alloys, Ni-Si-B series, Ni-PB series and other Ni series alloys, Co-Si-B series and other Co series alloys, etc.

[0059] In the soft magnetic powder, preferably the soft magnetic material is the main material, and impurities may be contained in addition. The main material refers to the material that accounts for 50% by mass or more of the particles of the soft magnetic powder. In addition, the content of the soft magnetic material in the particles of the soft magnetic powder is preferably 80% by mass or more, and more preferably 90% by mass or more.

[0060] In addition to the soft magnetic material, any additives may be added to the soft magnetic powder. Examples of such additives include various metal materials, various non-metal materials, and various metal oxide materials.

[0061] In addition, Figure 1 In the above, the height of the first peak P1 is set to H1, and the height of the second peak P2 is set to H2. The height H1 refers to the component of the length from the origin to the peak of the first peak P1 along the vertical axis of the orthogonal coordinate system depicting the particle size distribution curve. The height H2 refers to the component of the length from the origin to the peak of the second peak P2 along the vertical axis. In addition, the height H2 preferably satisfies the following formula (B-1) and the following formula (B-2).

[0062] H2=k2×H1…(B-1)

[0063] 0.2≤k2≤5.0…(B-2)

[0064] In addition, the coefficient k2 included in the above formula (B-1) satisfies the above formula (B-2), but more preferably satisfies the following formula (B-3), and further preferably satisfies the following formula (B-4).

[0065] 0.3≤k2≤4.0…(B-3)

[0066] 0.4≤k2≤2.0…(B-4)

[0067] In the soft magnetic powder showing such a particle size distribution curve, the balance between the amount of particles belonging to the first peak portion P1 and the amount of particles belonging to the second peak portion P2 is further optimized, thereby achieving a soft magnetic powder having particularly good filling properties.

[0068] It should be noted that when the coefficient k2 is lower than the lower limit, the volume ratio of the particles belonging to the first peak portion P1 becomes too large, so the balance of the amount of particles belonging to the first peak portion P1 and the particles belonging to the second peak portion P2 is easily destroyed, and the filling property may be reduced. On the other hand, when the coefficient k2 exceeds the upper limit, the volume ratio of the particles belonging to the second peak portion P2 becomes too large, so the above-mentioned balance of amount is easily destroyed, and the filling property may be reduced. In addition, the particle size becomes too large as a whole, so when used in a high frequency band, the eddy current loss in the particles in the powder compact may be easily increased.

[0069] also, Figure 1 The particle size distribution curve shown has a bottom B located between the first peak P1 and the second peak P2. The bottom B has a minimum value at a particle size D3 located between the particle size D1 and the particle size D2. Figure 1 , the height of the bottom B is set to H3. The height H3 refers to the component of the length from the origin to the bottom of the bottom B along the vertical axis of the orthogonal coordinate system depicting the particle size distribution curve. In addition, the height H3 preferably satisfies the following formula (C-1) and the following formula (C-2).

[0070] H3=k3×H1…(C-1)

[0071] k3≤0.9…(C-2)

[0072] In addition, the coefficient k3 included in the above formula (C-1) satisfies the above formula (C-2), but more preferably satisfies the following formula (C-3), and further preferably satisfies the following formula (C-4).

[0073] 0.1≤k3≤0.8…(C-3)

[0074] 0.1≤k3≤0.7…(C-4)

[0075] In the soft magnetic powder showing such a particle size distribution curve, the particle size balance between the particles belonging to the first peak portion P1 and the particles belonging to the second peak portion P2 is further optimized, thereby achieving a soft magnetic powder with particularly good filling properties.

[0076] It should be noted that when the coefficient k3 is lower than the lower limit, the balance of the amount of particles belonging to the first peak portion P1 and the amount of particles belonging to the second peak portion P2 is easily destroyed, and the filling property may be reduced. On the other hand, when the coefficient k3 exceeds the upper limit, the effect of improving the filling property brought by the bimodal distribution may become smaller.

[0077] If necessary, an insulating film may be provided on the surface of the particles of the soft magnetic powder. Examples of the insulating film include glass materials, ceramic materials, and resin materials.

[0078] It should be noted that the number of peaks of the particle size distribution curve of the soft magnetic powder is not limited to two, and may be three or more. That is, when the particle size distribution curve is drawn for the soft magnetic powder, the particle size distribution curve may also have a multimodal distribution. When the particle size distribution curve has three or more peaks, one of two adjacent peaks may be used as the first peak P1, and the other may be used as the second peak P2.

[0079] 2. Method for producing soft magnetic powder

[0080] Next, an example of a method for producing the above-mentioned soft magnetic powder will be described.

[0081] The soft magnetic powder is produced by mixing a first powder and a second powder having an average particle size larger than that of the first powder.

[0082] The first powder and the second powder may be powders manufactured by any method, respectively. As examples of manufacturing methods, in addition to various atomization methods such as water atomization, gas atomization, and rotating water flow atomization, reduction method, carbonyl method, and pulverization method may also be cited. Among them, the first powder and the second powder are preferably powders manufactured by atomization. By atomization, tiny powders with good particle shape can be efficiently manufactured. Therefore, by using powder manufactured by atomization (atomized powder), a soft magnetic powder with particularly high filling property can be obtained.

[0083] In addition, the manufacturing methods of the first powder and the second powder may be the same or different from each other. Since different characteristics of the powders manufactured by each manufacturing method can be derived in most cases, when the manufacturing methods are different, multiple characteristics that the soft magnetic powder is desired to have can be allocated to the first powder and the second powder. In this way, it is possible to manufacture a soft magnetic powder having multiple characteristics that powders obtained by the same manufacturing method cannot have.

[0084] Specifically, an example can be given in which a powder produced by a water atomization method is used as the first powder, and a powder produced by a rotating water flow atomization method is used as the second powder. In the water atomization method, since the high-speed jet of water collides with the molten metal to be miniaturized, a first powder having a particularly small diameter can be efficiently produced. In the rotating water flow atomization method, the molten metal can be miniaturized by colliding with a high-speed jet of gas, and then rushed into a rotating water flow to be rapidly cooled, so even a powder having a larger diameter than the powder based on the water atomization method can obtain a high cooling rate. Therefore, it is easy to obtain amorphous with a high degree of amorphism and microcrystalline with a small crystal size, and even a composition with high magnetic permeability and saturation magnetic flux density can efficiently produce a second powder having both low coercivity.

[0085] By making the average particle diameters of the first powder and the second powder the same, the specific surface area of ​​the second powder can be reduced to about half of that of the first powder. This suggests that the powder produced by the rotating water atomization method has a higher sphericity than the powder produced by the water atomization method.

[0086] In addition, due to the difference in the production method, for example, the coercive force of the second powder can be suppressed to about half of that of the first powder. This is considered to suggest that the swirling water atomization method has a higher cooling rate than the water atomization method.

[0087] By using such first and second powders, it is possible to easily obtain a soft magnetic powder that can produce a green compact having good filling properties and low magnetic properties and core loss in a high frequency band.

[0088] It should be noted that the first powder and the second powder thus produced may be classified as needed. Examples of classification methods include dry classification such as sieving classification, inertial classification, centrifugal classification, and wind classification, and wet classification such as sedimentation classification.

[0089] The first powder and the second powder are powders with low coercive force. The coercive force of the first powder and the second powder is preferably 5.0 [Oe] (398 [A / m]) or less, and more preferably 3.0 [Oe] (239 [A / m] or less. By using the first powder and the second powder with low coercive force, a powder compact can be manufactured that can fully suppress hysteresis loss even when used in a high frequency band.

[0090] The coercive force of the first powder and the second powder can be measured, for example, by a magnetization measuring device TM-VSM1230-MHHL manufactured by Tamagawa Seisakusho Co., Ltd.

[0091] 3.Powder cores and magnetic components

[0092] Next, a dust core and a magnetic element according to an embodiment will be described.

[0093] The magnetic element according to the embodiment can be applied to various magnetic elements having a magnetic core, such as a choke coil, an inductor, a noise filter, a reactor, a transformer, a motor, an actuator, a solenoid valve, a generator, etc. In addition, the powder magnetic core according to the embodiment can be applied to the magnetic core of these magnetic elements.

[0094] Hereinafter, two types of coil components will be described as representative examples of magnetic elements.

[0095] 3.1. Ring type

[0096] First, a toroidal coil component as an example of the magnetic element according to the embodiment will be described.

[0097] Figure 2 It is a top view schematically showing a toroidal coil component.

[0098] Figure 2 The coil component 10 shown has a ring-shaped powder magnetic core 11 and a conductive wire 12 wound around the powder magnetic core 11. Such a coil component 10 is generally called a toroidal coil.

[0099] The powder core 11 is obtained by mixing the soft magnetic powder and the binding material involved in the embodiment, supplying the obtained mixture to a molding die, and pressing and molding. That is, the powder core 11 is a powder body containing the soft magnetic powder involved in the embodiment. In such a powder core 11, the filling property of the soft magnetic powder is good, and the eddy current loss is small when used in a high frequency band. Therefore, the coil component 10 with the powder core 11 has low core loss and high magnetic properties such as magnetic permeability and magnetic flux density. As a result, when the coil component 10 is mounted on an electronic device, etc., the power consumption of the electronic device, etc. can be reduced, and high performance and miniaturization can be achieved.

[0100] As the constituent materials of the binding material used in the manufacture of the powder magnetic core 11, for example, organic materials such as silicone resins, epoxy resins, phenol resins, polyamide resins, polyimide resins, and polyphenylene sulfide resins, and inorganic materials such as phosphates such as magnesium phosphate, calcium phosphate, zinc phosphate, manganese phosphate, and cadmium phosphate, and silicates such as sodium silicate, etc., are listed, and thermosetting polyimide or epoxy resin is particularly preferred. These resin materials are easily cured by heating and have excellent heat resistance. Therefore, the ease of manufacture and heat resistance of the powder magnetic core 11 can be improved. It should be noted that the binding material can be added as needed or omitted.

[0101] In addition, the ratio of the binding material to the soft magnetic powder is slightly different, preferably from 0.5 mass % to 5.0 mass %, and more preferably from 1.0 mass % to 3.0 mass %, depending on the target magnetic properties or mechanical properties, the permissible eddy current loss, etc. of the manufactured powder magnetic core 11. Thus, the particles of the soft magnetic powder can be fully bonded to each other, and the coil component 10 with excellent magnetic properties can be obtained.

[0102] Various additives may be added to the mixture for any purpose as needed.

[0103] The conductive wire 12 may be made of a material having high conductivity, such as a metal material containing Cu, Al, Ag, Au, Ni, etc. An insulating film may be provided on the surface of the conductive wire 12 as necessary.

[0104] It should be noted that the shape of the powder core 11 is not limited to Figure 2 The ring shape shown may be, for example, a shape in which a part of the ring is missing, a shape in which the longitudinal direction is linear, a sheet shape, a film shape, or the like.

[0105] Furthermore, the powder core 11 may contain a soft magnetic powder or a non-magnetic powder other than the soft magnetic powder according to the above-mentioned embodiment, as necessary.

[0106] As described above, the coil component 10 as a magnetic element includes the powder core 11 containing the soft magnetic powder described above. This makes it possible to realize the coil component 10 having low core loss and excellent magnetic characteristics.

[0107] 3.2. Closed magnetic circuit type

[0108] Next, a closed magnetic circuit type coil component will be described as an example of the magnetic element according to the embodiment.

[0109] Figure 3 It is a perspective view schematically showing a closed magnetic circuit type coil component.

[0110] The closed magnetic circuit type coil component will be described below. However, in the following description, the differences from the annular type coil component will be mainly described, and the description of the same matters will be omitted.

[0111] like Figure 3As shown, the coil component 20 involved in this embodiment is formed by burying the conductive wire 22 formed into a coil shape inside the powder core 21. That is, the coil component 20 as a magnetic element has a powder core 21 containing the above-mentioned soft magnetic powder, and the conductive wire 22 is molded by the powder core 21. The powder core 21 has the same structure as the above-mentioned powder core 11. As a result, the coil component 20 with low core loss and excellent magnetic properties can be realized.

[0112] The coil component 20 of such a form is easy to obtain a relatively small component. In addition, the coil component 20 has high magnetic properties and low core loss. Therefore, when the coil component 20 is mounted on an electronic device, the power consumption of the electronic device can be reduced, and high performance and miniaturization can be achieved.

[0113] Furthermore, since the lead wire 22 is buried inside the powder core 21, a gap is unlikely to be generated between the lead wire 22 and the powder core 21. Therefore, vibration caused by magnetostriction of the powder core 21 can be suppressed, and noise caused by the vibration can be suppressed.

[0114] It should be noted that the shape of the powder core 21 is not limited to Figure 3 The shape shown may also be a sheet, a film, etc.

[0115] Furthermore, the powder core 21 may contain a soft magnetic powder or a non-magnetic powder other than the soft magnetic powder according to the above-mentioned embodiment, as necessary.

[0116] 4. Electronic devices

[0117] Next, based on Figures 4 to 6 An electronic device including the magnetic element according to the embodiment will be described.

[0118] Figure 4 It is a perspective view showing a mobile personal computer as an electronic device including the magnetic element according to the embodiment. Figure 4 The personal computer 1100 shown in the figure includes a main body 1104 including a keyboard 1102 and a display unit 1106 including a display unit 100. The display unit 1106 is rotatably supported by the main body 1104 via a hinge structure. Such a personal computer 1100 has a built-in magnetic element 1000 such as a choke coil or inductor for a switching power supply, a motor, or the like.

[0119] Figure 5 It is a top view showing a smartphone as an electronic device including the magnetic element according to the embodiment. Figure 5The smartphone 1200 shown includes a plurality of operation buttons 1202, an earpiece 1204, and a talk port 1206. The display unit 100 is disposed between the operation buttons 1202 and the earpiece 1204. Such a smartphone 1200 has magnetic components 1000 such as an inductor, a noise filter, and a motor built therein.

[0120] Figure 6 13 is a perspective view showing a digital still camera as an electronic device including a magnetic element according to an embodiment. The digital still camera 1300 generates an imaging signal by photoelectrically converting an optical image of a subject using an imaging element such as a CCD (Charge Coupled Device).

[0121] Figure 6 The digital still camera 1300 shown in the figure has a display unit 100 provided on the back of a housing 1302. The display unit 100 functions as a viewfinder for displaying an electronic image of a subject. In addition, a light receiving unit 1304 including an optical lens or a CCD is provided on the front side of the housing 1302, that is, the back side in the figure.

[0122] When the photographer checks the subject image displayed on the display unit 100 and presses the shutter button 1306, the imaging signal of the CCD at that time is transferred and stored in the memory 1308. Such a digital still camera 1300 also has a magnetic element 1000 such as an inductor or a noise filter built in.

[0123] As an electronic device according to an embodiment of the present invention, in addition to Figure 4 Personal computers, Figure 5 Smartphones, Figure 6 In addition to still digital cameras, examples include mobile phones, tablet terminals, watches, inkjet printers and other inkjet ejection devices, notebook personal computers, televisions, cameras, video recorders, car navigation devices, pagers, electronic notepads, electronic dictionaries, calculators, electronic game consoles, word processors, workstations, videophones, anti-theft television monitors, electronic binoculars, POS terminals, electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasonic diagnostic devices, electronic endoscopes and other medical equipment, fish finders, various measuring equipment, measuring instruments for vehicles, aircraft, and ships, mobile body control equipment such as automobile control equipment, aircraft control equipment, railway vehicle control equipment, and ship control equipment, flight simulators, etc.

[0124] As described above, such an electronic device includes the magnetic element according to the embodiment. Thus, the effects of the magnetic element such as low coercive force and low core loss can be enjoyed, and the performance of the electronic device can be improved.

[0125] 5. Mobile body

[0126] Next, based on Figure 7 A moving body including the magnetic element according to the present embodiment will be described.

[0127] Figure 7 It is a perspective view showing a car as a moving object including the magnetic element according to the embodiment.

[0128] The magnetic element 1000 is built into the automobile 1500. Specifically, the magnetic element 1000 is built into various automobile parts such as a car navigation system, an anti-lock braking system (ABS), an engine control unit, a battery control unit of a hybrid car or an electric car, a body posture control system, an electronic control unit (ECU: electronic control unit) such as an automatic driving system, a drive motor, a generator, and an air conditioning unit.

[0129] As described above, such a moving body includes the magnetic element according to the embodiment. Thus, the effects of the magnetic element such as low coercive force and low core loss can be enjoyed, and the high performance of the moving body can be achieved.

[0130] It should be noted that the mobile body involved in this embodiment has Figure 7 In addition to the automobile shown, for example, it may be a motorcycle, a bicycle, an aircraft, a helicopter, an unmanned aerial vehicle, a ship, a submarine, a train, a rocket, a spacecraft, etc.

[0131] As mentioned above, the soft magnetic powder, the powder magnetic core, the magnetic element, the electronic device, and the moving body of the present invention have been described based on the preferred embodiments, but the present invention is not limited thereto.

[0132] For example, in the above-described embodiment, as an example of application of the soft magnetic powder of the present invention, a compressed powder body such as a powder core is cited and described. However, the application example is not limited to this, and for example, magnetic devices such as a magnetic fluid, a magnetic head, and a magnetic shielding sheet may also be used.

[0133] Furthermore, the shapes of the powder magnetic core and the magnetic element are not limited to those shown in the drawings, and may be any shapes.

[0134] Example

[0135] Next, specific examples of the present invention will be described.

[0136] 6. Production of raw material powder

[0137] 6.1. Raw material powder No. 1 to 3

[0138] The soft magnetic powders of raw material powders No. 1 to 3 were produced by the swirling water atomization method. The properties of the soft magnetic powders of raw material powders No. 1 to 3 are shown in Table 1.

[0139] 6.2 Raw material powder No. 4 to 7

[0140] Soft magnetic powders of raw material powders No. 4 to 7 were produced by water atomization. The properties of the soft magnetic powders of raw material powders No. 4 to 7 are shown in Table 1.

[0141] 6.3 Raw material powder No.8

[0142] The soft magnetic powder of raw material powder No. 8 was produced by the swirling water atomization method. The properties of the soft magnetic powder of raw material powder No. 8 are shown in Table 1.

[0143] 7. Evaluation of raw material powder

[0144] 7.1. Average particle size

[0145] For the soft magnetic powder of each raw material powder No., a volume-based particle size distribution was obtained by a laser diffraction scattering particle size distribution measuring device. Then, based on the obtained particle size distribution, the average particle size was calculated. It should be noted that the average particle size is the particle size when the relative particle amount is 50 volume %. The obtained average particle size is shown in Table 1.

[0146] 7.2. Coercivity

[0147] The coercive force of the soft magnetic powder of each raw material powder No. was measured using VSM system TM-VSM1230-MHHL manufactured by Tamagawa Seisakusho Co., Ltd. as a magnetization measuring device. The measurement results are shown in Table 1.

[0148] 7.3. Magnetic loss (core loss)

[0149] The magnetic loss (core loss) of the soft magnetic powder of each raw material powder No. was measured by the following method.

[0150] First, a methyl ethyl ketone solution of epoxy resin as a binder was added to the soft magnetic powder of each raw material powder No. in an amount of 2.0 mass % solid content. The mixture was mixed and dried to form a block. The block was crushed and then pressed into an outer diameter of 1.0 mm at a molding pressure of 294 MPa. inner diameter The ring was shaped into a 3 mm thick ring and then heated at 150° C. for 30 minutes to form a toroidal magnetic core.

[0151] Next, the core loss Pcv of the obtained toroidal core was measured. It should be noted that the measurement conditions were 36 turns of the primary coil and 36 turns of the secondary coil, 1 MHz of measurement frequency, 30 mT of maximum magnetic flux density, and 21 of magnetic permeability μ'. The measurement results are shown in Table 1.

[0152] 7.4. Magnetic permeability

[0153] The magnetic permeability of the soft magnetic powder of each raw material powder No. was measured by the following method.

[0154] First, a methyl ethyl ketone solution of epoxy resin as a binder was added to the soft magnetic powder of each raw material powder No. in an amount of 2.0 mass % solid content. The mixture was mixed and dried to form a block. The block was crushed and then pressed into an outer diameter of 1.0 mm at a molding pressure of 294 MPa. inner diameter The ring was shaped into a 3 mm thick ring and then heated at 150° C. for 30 minutes to form a toroidal magnetic core.

[0155] Next, the magnetic permeability of the toroidal magnetic core at a frequency of 1 MHz was measured using a 4294A precision impedance analyzer (Precision Impedance Analyzer) manufactured by Agilent. The measurement results are shown in Table 1.

[0156] [Table 1]

[0157]

[0158] 8. Manufacture of soft magnetic powder

[0159] 8.1 Example 1

[0160] Raw material powder No. 5 was used as the first powder, and raw material powder No. 1 was used as the second powder, and they were mixed. Thus, a soft magnetic powder was obtained. It should be noted that the mixing conditions of the first powder and the second powder are shown in Table 2.

[0161] 8.2. Examples 2 to 17

[0162] A soft magnetic powder was obtained in the same manner as in Example 1 except that the mixing conditions of the first powder and the second powder were changed as shown in Table 2 or Table 3.

[0163] 8.3. Comparative Examples 1 to 4

[0164] Except that the production conditions of the soft magnetic powder were as shown in Table 2 or Table 3, the same procedure as in Example 1 was carried out to obtain a soft magnetic powder.

[0165] [Table 2]

[0166]

[0167] [Table 3]

[0168]

[0169] 9. Evaluation of soft magnetic powder

[0170] 9.1. Particle size distribution

[0171] About the soft magnetic powder of each embodiment and each comparative example, the particle size distribution of volume basis is obtained by laser diffraction scattering type particle size distribution measuring device. Then, based on the particle size distribution obtained, a particle size distribution curve is made. In addition, when the obtained particle size distribution curve has a bimodal distribution, particle diameter D1, particle diameter D2, difference D2-D1, coefficient k1, height H1, height H2, coefficient k2, height H3 and coefficient k3 are recorded in Table 4 and Table 5. On the other hand, when the obtained particle size distribution curve does not have a bimodal distribution, in Table 4 and Table 5, only either particle diameter D1 or particle diameter D2, and either height H1 or height H2 are recorded.

[0172] Figure 8 This is a graph showing the particle size distribution curves obtained for the soft magnetic powders of Examples 1 to 5 in an overlapping manner. Fig. 9 This is a graph showing the particle size distribution curves obtained for the soft magnetic powders of Examples 6 to 9 and Comparative Example 2 in a superimposed manner. Fig.10 Graph showing the particle size distribution curves obtained for the soft magnetic powders of Examples 10 to 14 in an overlapping manner. Figures 8 to 10 In the embodiment, the mixing ratio of the first powder and the second powder is described as 5:5, for example.

[0173] like Figures 8 to 10 As shown, by changing the mixing ratio of the first powder and the second powder, the height of the first peak portion P1 , the height of the second peak portion P2 , and the height of the bottom B can be controlled according to the mixing ratio.

[0174] 9.2. Magnetic loss (core loss)

[0175] Using the soft magnetic powder of each embodiment and each comparative example, a toroidal core was produced by the same method as in 7.3. Next, the core loss Pcv of the obtained toroidal core was measured. It should be noted that the measurement conditions were the same as in 7.3. The measurement results are shown in Table 4 or Table 5.

[0176] 9.3. Magnetic permeability

[0177] Using the soft magnetic powder of each example and each comparative example, a toroidal core was produced by the same method as in 7.4. Next, the magnetic permeability of the obtained toroidal core was measured by the same method as in 7.4. The measurement results are shown in Table 4 or Table 5.

[0178] [Table 4]

[0179]

[0180] [Table 5]

[0181]

[0182] As can be seen from Tables 4 and 5, the soft magnetic powders of each embodiment have a bimodal distribution whose particle size distribution curve satisfies the specified conditions. In addition, the powder compacts made from the soft magnetic powders of each embodiment have good magnetic permeability and core loss compared to the powder compacts made from the soft magnetic powders of each comparative example. It is inferred that the soft magnetic powders of each embodiment can produce powder compacts with good filling properties and low eddy current loss when used in a high frequency band.

Claims

1. A soft magnetic powder, characterized in that: The volume-based particle size distribution is measured by a laser diffraction scattering particle size distribution measuring device, and the particle size distribution is plotted in an orthogonal coordinate system in which the horizontal axis is the particle diameter and the vertical axis is the relative particle amount to draw a particle size distribution curve. At this time, The particle size distribution curve has: a first peak having a maximum value at a particle size D1; and a second peak having a maximum value at a particle size D2 greater than the particle size D1, wherein the particle sizes D1 and D2 are in units of μm. The soft magnetic powder contains two or more particles with different crystal structures. The particle size D1 is within a range of 1.0 μm or more and 16.0 μm or less. The particle size D2 is within a range of 15.0 μm or more and 45.0 μm or less. The difference D2-D1 between the particle diameter D1 and the particle diameter D2 satisfies the following formula (A-1) and the following formula (A-2): When the height of the first peak is set to H1 and the height of the second peak is set to H2, the height H2 satisfies the following formula (B-1) and the following formula (B-2): D2-D1=k1×D1 (A-1), 1.0≤k1≤15.0 (A-2), H2=k2×H1 (B-1), 0.2≤k2≤5.0 (B-2).

2. The soft magnetic powder according to claim 1, characterized in that The soft magnetic powder contains two or more types of particles having different alloy compositions.

3. The soft magnetic powder according to claim 1, characterized in that The particle size distribution curve has a bottom with a minimum value at a particle size D3 between the particle size D1 and the particle size D2. When the height of the bottom is set to H3, the height H3 satisfies the following formula (C-1) and the following formula (C-2): H3=k3×H1 (C-1), k3<0.9 (C-2).

4. A powder magnetic core, characterized in that: Contains the soft magnetic powder according to any one of claims 1 to 3.

5. A magnetic element, characterized in that: A powder magnetic core according to claim 4 is provided.

6. An electronic device, characterized in that: A magnetic element according to claim 5.

7. A mobile body, characterized in that: A magnetic element according to claim 5.

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