Soft magnetic powder, dust core, magnetic element, electronic device and mobile device

Abstract

To provide a soft-magnetic powder allowing for producing a compact preferable in chargeability and less in eddy current loss when used in a high-frequency band, and a magnetic powder core, a magnetic element, an electronic appliance and a movable body.SOLUTION: A soft-magnetic powder is provided wherein, when measuring a volume-based particle-size distribution by a laser-diffractive / scattering particle-size distribution measuring instrument and depicting a particle-size distribution curve by plotting the particle-size distribution onto an orthogonal coordinate system with an abscissa taken as particle size and an ordinate as the relative amount of particles, the particle-size distribution curve has a first peak portion having a maximal value at a particle size D1 [μm] and a second peak portion having a maximal value at a particle size D2 [μm] greater than the particle size D1, in which the particle size D1 lies within a range of 1.0 μm or greater and 16.0 μm or smaller and a difference D2-D1 between the particle size D1 and the particle size D2 satisfies the below expressions (A-1) and (A-2). D2-D1=k1×D1 ... (A-1) 1.0≤k1≤15.0 ... (A-2)SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a soft magnetic powder, a dust core, a magnetic element, an electronic device, and a mobile object. [Background technology]

[0002] Patent Document 1 discloses a soft magnetic solid material obtained by compressing and solidifying soft magnetic powder having an insulating coating, and discloses that a bimodal powder mixture with two particle size peaks is used as the soft magnetic powder from the viewpoint of the powder packing rate. This makes it possible to increase the density of the soft magnetic solid material. And by increasing the density, it is possible to increase the magnetic permeability of the soft magnetic solid material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-234206 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 does not clearly state how to set the two particle size peaks in a bimodal powder mixing system. The particle size peaks affect the packing property and core loss. Therefore, it is necessary to optimize the two particle size peaks. [Means for solving the problem]

[0005] The soft magnetic powder according to the application example of the present invention is The particle size distribution on a volume basis is measured using a laser diffraction scattering type particle size distribution measuring device, and the particle size distribution is The particle size distribution curve is obtained by plotting the cloth on an orthogonal coordinate system with the particle size on the horizontal axis and the relative particle amount on the vertical axis. When I drew The particle size distribution curve has a first peak portion having a maximum value at a particle size D1 [μm] and a second peak portion having a maximum value at a particle size D1 A second peak portion having a maximum value at a larger particle diameter D2 [μm], The particle size D1 is in the range of 1.0 μm or more and 16.0 μm or less, The particle size D2 is within the range of 15.0 μm or more and 50.0 μm or less, The difference D2-D1 between the particle diameter D1 and the particle diameter D2 is expressed by the following formula (A-1) and the following formula (A -2) is satisfied death, When the height of the first peak portion is H1 and the height of the second peak portion is H2, The height H2 is lower than the height H1, and is expressed by the following formula (B-1) and the following formula (B-2): Fulfilling The particle size distribution curve has a minimum value at a particle size D3 located between the particle size D1 and the particle size D2. a bottom portion having When the height of the bottom portion is H3, the height H3 is determined by the following formula (C-1) and the following formula (C-2): Satisfying formula (C-2) It is characterized by: 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) H3=k3×H1 … (C-1) k3<0.9 … (C-2)

[0006] The powder magnetic core according to the application example of the present invention is The soft magnetic powder according to the application example of the present invention is included.

[0007] The magnetic element according to the application example of the present invention includes: The present invention is characterized by including a powder magnetic core according to an application example of the present invention.

[0008] The electronic device according to the application example of the present invention includes: The present invention is characterized by including a magnetic element according to an application example of the present invention.

[0009] A moving body according to an application example of the present invention is The present invention is characterized by including a magnetic element according to an application example of the present invention. [Brief description of the drawings]

[0010] [Figure 1] FIG. 4 is a diagram showing an example of a particle size distribution curve PSD obtained for the soft magnetic powder according to the embodiment. [Diagram 2] FIG. 2 is a plan view illustrating a schematic diagram of a toroidal type coil component. [Diagram 3] FIG. 2 is a see-through perspective view that typically illustrates a closed magnetic circuit type coil component. [Figure 4] FIG. 1 is a perspective view showing a mobile personal computer, which is an electronic device including a magnetic element according to an embodiment. [Diagram 5] FIG. 1 is a plan view showing a smartphone, which is an electronic device including a magnetic element according to an embodiment. [Figure 6] FIG. 1 is a perspective view showing a digital still camera, which is an electronic device including a magnetic element according to an embodiment. [Figure 7] FIG. 1 is a perspective view showing an automobile, which is a moving body including a magnetic element according to an embodiment. [Figure 8] 2 is a graph showing particle size distribution curves obtained for the soft magnetic powders of Examples 1 to 5 superimposed on each other. [Figure 9] 2 is a graph showing particle size distribution curves obtained for the soft magnetic powders of Examples 6 to 9 and Comparative Example 2, superimposed on each other. [Figure 10] 2 is a graph showing particle size distribution curves obtained for the soft magnetic powders of Examples 10 to 14. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The soft magnetic powder, the dust core, the magnetic element, the electronic device, and the mobile object of the present invention will be described in detail below with reference to the accompanying drawings.

[0012] 1. Soft magnetic powder First, the soft magnetic powder according to the embodiment will be described. The soft magnetic powder according to the embodiment is a powder containing soft magnetic particles and having a bimodal distribution (two-peak distribution) in which the particle size distribution curve has two peaks.

[0013] Specifically, first, in the soft magnetic powder according to the embodiment, when the volume-based particle size distribution is measured by a laser diffraction scattering type 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 on an orthogonal coordinate system with the particle size on the horizontal axis and the relative particle amount on the vertical axis. Note that examples of the laser diffraction scattering type particle size distribution measuring device include Microtrack, HRA9320-X100, manufactured by Nikkiso Co., Ltd.

[0014] FIG. 1 is a diagram showing an example of a particle size distribution curve PSD obtained for the soft magnetic powder according to the embodiment.

[0015] The particle size distribution curve PSD shown in Figure 1 is a curve having a first peak P1 with a maximum value at a particle size D1 [μm] and a second peak P2 with a maximum value at a particle size D2 [μm] larger than the particle size D1. The particle size D1 is located in the range of 1.0 μm to 16.0 μm. 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). D2-D1=k1×D1 … (A-1) 1.0≦k1≦15.0 … (A-2)

[0016] In such soft magnetic powders, the bimodal characteristics are optimized, so the particle size balance between the large and small particles is good, and the overall particle size is small. Therefore, the soft magnetic powder according to the embodiment has good packing properties, and is a powder that can be used to manufacture a green compact with low eddy current loss when used in the high frequency band. As a result, a green compact with good magnetic properties such as magnetic permeability and magnetic flux density and low core loss can be realized. Examples of the green compact include a green compact core, a green compact sheet, and a green compact film.

[0017] As described above, the first peak P1 has a maximum value at the particle diameter D1 [μm], which is located in the 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.

[0018] If 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 compact are reduced. On the other hand, if the particle size D1 is above the upper limit, eddy current loss increases in the particles in the compact when used in a high frequency band.

[0019] As described above, the second peak portion P2 has a maximum value at the particle diameter D2 [μm]. The coefficient k1 included in the above formula (A-1) satisfies the above formula (A-2), but preferably satisfies the following formula (A-3), and more preferably satisfies the following formula (A-4).

[0020] 2.0≦k1≦14.0 … (A-3) 4.0≦k1≦12.0 … (A-4)

[0021] If the coefficient k1 is below the lower limit, the first peak P1 and the second peak P2 will approach each other. This will cause the balance between the large and small particles to be lost, and the packing ability of the soft magnetic powder will decrease. On the other hand, if the coefficient k1 is above the upper limit, the first peak P1 and the second peak P2 will be separated from each other. This will cause the balance between the large and small particles to be lost, and the packing ability of the soft magnetic powder will decrease. In addition, if the particle size D2 becomes too large, eddy current loss will increase in the particles in the compact when used in a high frequency band.

[0022] Also, the particle diameter D2 is preferably in the range of 15.0 μm or more and 50.0 μm or less, more preferably 25.0 μm or more and 45.0 μm or less, and even more preferably 28.0 μm or more and 40.0 μm or less.

[0023] By setting the particle size D2 within the above range, the particle size balance between the large particles and the small particles can be improved, and the particle size as a whole can be prevented from becoming too large. As a result, a soft magnetic powder can be obtained that can improve the magnetic properties of the compact and reduce core loss.

[0024] The soft magnetic material constituting this soft magnetic powder may be one type or a mixture of two or more types. In other words, since the soft magnetic powder is an aggregate of many soft magnetic particles, it can take the form of a mixed powder having particles made of a first soft magnetic material and particles made of a second soft magnetic material having a different alloy composition from the first soft magnetic material. A mixed powder having two or more types of particles with different alloy compositions can provide a soft magnetic powder having magnetic properties derived from both the first soft magnetic material and the second soft magnetic material. For this reason, for example, a green compact with particularly high magnetic properties can be obtained.

[0025] The soft magnetic powder is mainly made of a soft magnetic material. Examples of the soft magnetic material include pure iron, Fe-Si alloys such as silicon steel, Fe-Ni alloys such as permalloy, Fe-Co alloys such as permendur, Fe-Si-Al alloys such as sendust, Fe-Cr-Si alloys, Fe-Cr-Al alloys, and various Fe alloys, as well as various Ni alloys and various Co alloys. Among these, various Fe alloys are preferably used from the viewpoints of magnetic properties such as magnetic permeability and magnetic flux density, and cost.

[0026] Furthermore, the crystal structure of the soft magnetic material is not particularly limited, and may be crystalline, non-crystalline (amorphous), or microcrystalline (nanocrystalline). Crystalline soft magnetic materials are relatively inexpensive, which contributes to reducing the cost of soft magnetic powder. Amorphous soft magnetic materials tend to have higher magnetic permeability and lower coercive force than crystalline soft magnetic materials, which contributes to improving the magnetic properties of the compact and reducing core loss. Microcrystalline soft magnetic materials tend to have higher magnetic permeability and saturation magnetic flux density than amorphous soft magnetic materials, which contributes to further improving the magnetic properties of the compact.

[0027] Therefore, it is preferable that the soft magnetic powder contains two or more types of particles with different crystal structures, which makes it possible to realize a soft magnetic powder that combines two or more different properties depending on the crystal structure.

[0028] Of these, the soft magnetic powder preferably contains an amorphous soft magnetic material or a microcrystalline soft magnetic material. By containing these, the magnetic properties of the soft magnetic powder can be improved and a low coercive force can be achieved. As a result, a green compact with particularly high magnetic properties and further reduced core loss can be achieved.

[0029] 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 realizing a soft magnetic powder having the properties of both powders.

[0030] A microcrystalline soft magnetic material is a soft magnetic material containing crystal grains with a crystal grain size of 1.0 nm to 30.0 nm. In a microcrystalline soft magnetic material, the volume ratio of the crystal grains is preferably 30 volume % or more, and more preferably 40 volume % or more.

[0031] Examples of amorphous soft magnetic materials and microcrystalline soft magnetic materials include Fe-based alloys such as Fe-Si-B, Fe-Si-BC, Fe-Si-B-Cr-C, Fe-Si-Cr, Fe-B, Fe-PC, Fe-Co-Si-B, Fe-Si-B-Nb, Fe-Si-B-Nb-Cu, and Fe-Zr-B, Ni-based alloys such as Ni-Si-B and Ni-PB, and Co-based alloys such as Co-Si-B.

[0032] In the soft magnetic powder, the soft magnetic material is preferably the main material, and other impurities may be included. The main material refers to a material that occupies 50% or more by mass of the particles of the soft magnetic powder. The content of the soft magnetic material in the particles of the soft magnetic powder is preferably 80% or more by mass, and more preferably 90% or more by mass.

[0033] In addition to the soft magnetic material, any additive may be added to the soft magnetic powder, such as various metal materials, various non-metal materials, various metal oxide materials, and the like.

[0034] In Fig. 1, the height of the first peak P1 is H1, and the height of the second peak P2 is H2. The height H1 refers to the length from the origin to the peak top of the first peak P1 along the vertical axis of the orthogonal coordinate system on which the particle size distribution curve is drawn. The height H2 refers to the length from the origin to the peak top of the second peak P2 along the vertical axis. The height H2 preferably satisfies the following formula (B-1) and formula (B-2).

[0035] H2=k2×H1 … (B-1) 0.2≦k2≦5.0 … (B-2)

[0036] Furthermore, 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).

[0037] 0.3≦k2≦4.0 … (B-3) 0.4≦k2≦2.0 … (B-4)

[0038] In a soft magnetic powder exhibiting such a particle size distribution curve, the quantitative balance between the particles belonging to the first peak portion P1 and the particles belonging to the second peak portion P2 is more optimized, thereby realizing a soft magnetic powder with particularly good packing properties.

[0039] If the coefficient k2 is below the lower limit, the volume ratio of the particles belonging to the first peak portion P1 becomes too large, which may cause the quantitative balance between the particles belonging to the first peak portion P1 and the particles belonging to the second peak portion P2 to be easily disturbed, and the packing property may be deteriorated. On the other hand, if the coefficient k2 is above the upper limit, the volume ratio of the particles belonging to the second peak portion P2 becomes too large, which may cause the quantitative balance to be easily disturbed, and the packing property may be deteriorated. In addition, the particle size becomes too large overall, which may cause the eddy current loss to increase in the particles in the compact when used in a high frequency band.

[0040] Furthermore, the particle size distribution curve shown in FIG. 1 has a bottom part B located between the first peak part P1 and the second peak part P2. The bottom part B has a minimum value at a particle size D3 located between particle size D1 and particle size D2. In FIG. 1, the height of the bottom part B is H3. The height H3 refers to the length from the origin to the bottom of the bottom part B along the vertical axis of the orthogonal coordinate system on which the particle size distribution curve is drawn. The height H3 preferably satisfies the following formula (C-1) and the following formula (C-2).

[0041] H3=k3×H1 … (C-1) k3≦0.9 … (C-2)

[0042] Furthermore, 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).

[0043] 0.1≦k3≦0.8 … (C-3) 0.1≦k3≦0.7 … (C-4)

[0044] In a 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, which makes it possible to realize a soft magnetic powder with particularly good packing properties.

[0045] If the coefficient k3 is below the lower limit, the quantitative balance between the particles belonging to the first peak portion P1 and the particles belonging to the second peak portion P2 is likely to be lost, and the packing property may be reduced. On the other hand, if the coefficient k3 is above the upper limit, the effect of improving the packing property by the bimodal distribution may be reduced.

[0046] The surface of the soft magnetic powder may be provided with an insulating coating, if necessary. Examples of the insulating coating include glass, ceramic, and resin materials.

[0047] The number of peaks in the particle size distribution curve of the soft magnetic powder is not limited to two, and may be three or more. That is, when a particle size distribution curve is drawn for the soft magnetic powder, the particle size distribution curve may have a multimodal distribution. When the particle size distribution curve has three or more peaks, one of two adjacent peaks may be designated as the first peak P1, and the other as the second peak P2.

[0048] 2. Manufacturing method of soft magnetic powder Next, an example of a method for producing the above-mentioned soft magnetic powder will be described. The above-mentioned soft magnetic powder is produced by mixing a first powder with a second powder having an average particle size larger than that of the first powder.

[0049] The first powder and the second powder may be powders produced by any method. Examples of the production method include various atomization methods such as water atomization, gas atomization, and rotary water flow atomization, as well as reduction, carbonyl, and pulverization. Of these, powders produced by the atomization method are preferably used for the first powder and the second powder. According to the atomization method, fine powders with good particle shapes can be efficiently produced. Therefore, by using powders produced by the atomization method (atomized powders), soft magnetic powders with particularly high filling properties can be obtained.

[0050] The first powder and the second powder may be manufactured by the same method or different methods. Since different properties of the powders manufactured by each manufacturing method are often brought out, in the latter case, multiple properties that are desired to be imparted to the soft magnetic powder can be allocated to the first powder and the second powder. This makes it possible to manufacture a soft magnetic powder that has multiple properties that cannot be obtained by powders manufactured by the same manufacturing method.

[0051] Specifically, the powder produced by the water atomization method is the first powder, and the powder produced by the rotating water atomization method is the second powder. In the water atomization method, water injected at high speed is collided with molten metal to make it fine, so that the first powder, especially with a small diameter, can be efficiently produced. In the rotating water atomization method, molten metal is collided with gas injected at high speed to make it fine, and then it is plunged into a rotating water flow to be rapidly cooled, so that even with powder with a larger diameter than that of the water atomization method, a high cooling rate can be obtained. Therefore, amorphous material with a high degree of amorphousness and microcrystalline material with a small crystal size can be easily obtained, and even if the composition has high magnetic permeability and saturation magnetic flux density, the second powder having low coercivity can be efficiently produced.

[0052] Due to these differences in manufacturing methods, when the first and second powders have the same average particle size, for example, the specific surface area of ​​the second powder can be reduced to about half that of the first powder. This is believed to suggest that the powder manufactured by the rotary water flow atomization method has higher particle sphericity than the powder manufactured by the water atomization method.

[0053] In addition, due to the difference in the manufacturing method, for example, the coercive force of the second powder can be reduced to about half that of the first powder, which is believed to suggest that the cooling rate of the rotating water flow atomization method is higher than that of the water atomization method.

[0054] By using such first powder and second powder, it is possible to easily obtain a soft magnetic powder that has good packing properties and that can be used to produce a green compact having low magnetic properties and low core loss in high frequency bands.

[0055] The first and second powders thus produced may be classified as necessary. Examples of the classification method include dry classification such as sieving classification, inertial classification, centrifugal classification, and air classification, and wet classification such as sedimentation classification.

[0056] The first powder and the second powder each have a 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 each having a low coercive force, a green compact can be manufactured that can sufficiently suppress hysteresis loss even when used in a high frequency band.

[0057] The coercive forces 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.

[0058] 3. Powder cores and magnetic components Next, the powder magnetic core and the magnetic element according to the embodiment will be described. 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, an electromagnetic valve, a generator, etc. Furthermore, the powder magnetic core according to the embodiment can be applied to the magnetic cores included in these magnetic elements.

[0059] Two types of coil components will be described below as representative examples of the magnetic element. 3.1.Toroidal type First, a toroidal type coil component, which is an example of a magnetic element according to the embodiment, will be described. FIG. 2 is a plan view that illustrates a schematic diagram of a toroidal type coil component.

[0060] 2 has a ring-shaped powder magnetic core 11 and a conductive wire 12 wound around this powder magnetic core 11. Such a coil component 10 is generally called a toroidal coil.

[0061] The powder magnetic core 11 is obtained by mixing the soft magnetic powder according to the embodiment with a binder, supplying the mixture to a molding die, and pressing and molding it. That is, the powder magnetic core 11 is a compact containing the soft magnetic powder according to the embodiment. In such a powder magnetic core 11, the filling property of the soft magnetic powder is good, and eddy current loss is small when used in a high frequency band. Therefore, the coil component 10 including the powder magnetic 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, the power consumption of the electronic device can be reduced and the electronic device can be made compact and high-performance.

[0062] Examples of the binder used to manufacture the powder magnetic core 11 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, and thermosetting polyimide or epoxy resins are 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. The binder may be added as necessary, or may be omitted.

[0063] The ratio of binder to soft magnetic powder varies slightly depending on the desired magnetic properties, mechanical properties, allowable eddy current loss, etc. of the powder core 11 to be produced, but is preferably about 0.5% by mass to 5.0% by mass, and more preferably about 1.0% by mass to 3.0% by mass. This allows the particles of the soft magnetic powder to be sufficiently bound together, while providing a coil component 10 with excellent magnetic properties. If necessary, various additives may be added to the mixture for any purpose.

[0064] The conductive wire 12 may be made of a highly conductive material, 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.

[0065] The shape of the powder magnetic core 11 is not limited to the ring shape shown in FIG. 2, but may be, for example, a ring shape in which part of the ring is missing, a shape in which the longitudinal direction is linear, or a sheet or film shape. Furthermore, the powder magnetic core 11 may contain soft magnetic powder other than the soft magnetic powder according to the embodiment described above or non-magnetic powder, as necessary.

[0066] As described above, the coil component 10, which is a magnetic element, includes the dust core 11 containing the soft magnetic powder described above. This makes it possible to realize the coil component 10 with low core loss and excellent magnetic properties.

[0067] 3.2.Closed magnetic circuit type Next, a closed magnetic circuit type coil component, which is an example of a magnetic element according to the embodiment, will be described. FIG. 3 is a see-through perspective view that typically shows a closed magnetic circuit type coil component.

[0068] The closed magnetic circuit type coil component will be described below, but in the following description, the differences from the toroidal type coil component will be mainly described, and a description of similar points will be omitted.

[0069] 3, the coil component 20 according to this embodiment is formed by embedding a conductor wire 22 formed into a coil shape inside a powder core 21. That is, the coil component 20, which is a magnetic element, includes a powder core 21 containing the soft magnetic powder described above, and is formed by molding the conductor wire 22 with the powder core 21. This powder core 21 has a similar configuration to the powder core 11 described above. This makes it possible to realize a coil component 20 with low core loss and excellent magnetic properties.

[0070] The coil component 20 of this type can be easily obtained as a relatively small one. Moreover, the coil component 20 has high magnetic properties and low core loss. Therefore, when the coil component 20 is mounted in an electronic device or the like, it is possible to reduce the power consumption of the electronic device or the like and to achieve high performance and miniaturization.

[0071] Furthermore, because the conductive wire 22 is embedded inside the powder core 21, a gap is unlikely to occur between the conductive wire 22 and the powder core 21. This makes it possible to suppress vibrations caused by magnetostriction of the powder core 21, and also to suppress the generation of noise associated with this vibration.

[0072] The shape of the powder magnetic core 21 is not limited to the shape shown in FIG. 3, and may be a sheet, a film, or the like. Furthermore, the dust core 21 may contain soft magnetic powder other than the soft magnetic powder according to the embodiment described above or non-magnetic powder, as necessary.

[0073] 4.Electronic equipment Next, an electronic device including the magnetic element according to the embodiment will be described with reference to FIGS.

[0074] Fig. 4 is a perspective view showing a mobile personal computer, which is an electronic device including a magnetic element according to the embodiment. The personal computer 1100 shown in Fig. 4 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 includes a magnetic element 1000, such as a choke coil or inductor for a switching power supply, or a motor.

[0075] Fig. 5 is a plan view showing a smartphone, which is an electronic device including the magnetic element according to the embodiment. The smartphone 1200 shown in Fig. 5 includes a plurality of operation buttons 1202, an earpiece 1204, and a mouthpiece 1206. A display unit 100 is disposed between the operation buttons 1202 and the earpiece 1204. Such a smartphone 1200 includes a built-in magnetic element 1000, such as an inductor, a noise filter, or a motor.

[0076] 6 is a perspective view showing a digital still camera, which is an electronic device including the magnetic element according to the embodiment. The digital still camera 1300 photoelectrically converts an optical image of a subject using an imaging element such as a CCD (Charge Coupled Device) to generate an imaging signal.

[0077] 6 includes a display unit 100 provided on the back of a case 1302. The display unit 100 functions as a viewfinder that displays a subject as an electronic image. In addition, a light receiving unit 1304 including an optical lens, a CCD, etc. is provided on the front side of the case 1302, i.e., on the back side in the figure.

[0078] When the photographer checks the subject image displayed on the display unit 100 and presses the shutter button 1306, the image signal of the CCD at that time is transferred to and stored in memory 1308. Such a digital still camera 1300 also has a built-in magnetic element 1000, such as an inductor or a noise filter.

[0079] Examples of electronic devices according to the embodiments include the personal computer of FIG. 4, the smartphone of FIG. 5, and the digital still camera of FIG. 6, as well as mobile phones, tablet terminals, watches, inkjet discharge devices such as inkjet printers, laptop personal computers, televisions, video cameras, video tape recorders, car navigation devices, pagers, electronic organizers, electronic dictionaries, calculators, electronic game devices, word processors, workstations, videophones, security television monitors, electronic binoculars, POS terminals, medical devices such as electronic thermometers, blood pressure monitors, blood glucose meters, electrocardiogram measuring devices, ultrasonic diagnostic devices, and electronic endoscopes, fish finders, various measuring devices, instruments for vehicles, aircraft, and ships, mobile object control devices such as automobile control devices, aircraft control devices, railway vehicle control devices, and ship control devices, and flight simulators.

[0080] As described above, such electronic devices include the magnetic element according to the embodiment, thereby enjoying the effects of the magnetic element, such as low coercive force and low core loss, and improving the performance of the electronic devices.

[0081] 5. Mobile Next, a moving body including the magnetic element according to this embodiment will be described with reference to FIG. FIG. 7 is a perspective view showing an automobile, which is a moving object including the magnetic element according to the embodiment. 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 antilock braking system (ABS), an engine control unit, a battery control unit for a hybrid automobile or an electric automobile, a vehicle attitude control system, an electronic control unit (ECU) for an automatic driving system, a drive motor, a generator, an air conditioning unit, and the like.

[0082] As described above, such a moving body includes the magnetic element according to the embodiment, thereby enjoying the effects of the magnetic element, such as low coercive force and low core loss, and improving the performance of the moving body. Note that the moving body according to this embodiment may be, for example, a motorcycle, a bicycle, an airplane, a helicopter, a drone, a ship, a submarine, a train, a rocket, a spaceship, or the like, in addition to the automobile shown in FIG.

[0083] The soft magnetic powder, dust core, magnetic element, electronic device, and mobile object of the present invention have been described above based on the preferred embodiments, but the present invention is not limited thereto. For example, in the above embodiment, a powder compact such as a powder core has been described as an example of an application of the soft magnetic powder of the present invention, but the application examples are not limited to this and may also be magnetic devices such as magnetic fluids, magnetic heads, and magnetic shielding sheets. Furthermore, the shapes of the dust core and the magnetic element are not limited to those shown in the drawings, and may be any shape. EXAMPLES

[0084] Next, specific examples of the present invention will be described. 6. Manufacturing raw powder 6.1. Raw material powder No.1~3 The soft magnetic powders of raw material powders No. 1 to 3 were produced by the rotary water flow atomization method. The properties of the soft magnetic powders of raw material powders No. 1 to 3 are as shown in Table 1.

[0085] 6.2. Raw material powder No.4~7 The soft magnetic powders of raw material powder Nos. 4 to 7 were produced by water atomization. The attributes of the soft magnetic powders of raw material powder Nos. 4 to 7 are as shown in Table 1.

[0086] 6.3. Raw material powder No.8 Soft magnetic powder of raw material powder No. 8 was produced by the rotary water flow atomization method. The properties of soft magnetic powder of raw material powder No. 8 are as shown in Table 1.

[0087] 7. Evaluation of raw powder 7.1. Average particle size For each soft magnetic powder of raw powder No., a volumetric particle size distribution was obtained using a laser diffraction scattering type particle size distribution measuring device. Then, based on the obtained particle size distribution, the average particle size was calculated. 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.

[0088] 7.2.Coercive force The coercive force of each soft magnetic powder of raw powder No. was measured using a magnetization measuring device, VSM System TM-VSM1230-MHHL, manufactured by Tamagawa Seisakusho Co., Ltd. The measurement results are shown in Table 1.

[0089] 7.3.Magnetic loss (core loss) For each of the soft magnetic powder raw material powder numbers, the magnetic loss (core loss) was measured by the following method. First, a methyl ethyl ketone solution of epoxy resin, which is a binder, was added to the soft magnetic powder of each raw powder No. so that the amount of addition was 2.0 mass% in terms of solid content. This was mixed and dried to form a mass. After the mass was crushed, it was press-molded at a molding pressure of 294 MPa into a ring shape with an outer diameter of φ14 mm, an inner diameter of φ7 mm, and a thickness of 3 mm. Next, it was heated at 150°C for 30 minutes to form a toroidal core.

[0090] Next, the core loss Pcv of the obtained toroidal core was measured under the following measurement conditions: the number of turns of the primary coil and the number of turns of the secondary coil were 36 turns each, the measurement frequency was 1 MHz, the maximum magnetic flux density was 30 mT, and the magnetic permeability μ' was 21. The measurement results are shown in Table 1.

[0091] 7.4.Magnetic permeability For each of the raw material powder numbers, the soft magnetic powder was measured for magnetic permeability by the following method. First, a methyl ethyl ketone solution of epoxy resin, which is a binder, was added to the soft magnetic powder of each raw powder No. so that the amount of addition was 2.0 mass% in terms of solid content. This was mixed and dried to form a mass. After the mass was crushed, it was press-molded at a molding pressure of 294 MPa into a ring shape with an outer diameter of φ14 mm, an inner diameter of φ7 mm, and a thickness of 3 mm. Next, it was heated at 150°C for 30 minutes to form a toroidal core.

[0092] Next, the magnetic permeability of this toroidal core was measured at a frequency of 1 MHz using an Agilent 4294A precision impedance analyzer. The measurement results are shown in Table 1.

[0093] [Table 1]

[0094] 8. Manufacturing of soft magnetic powder 8.1. Example 1 Raw material powder No. 5 was used as the first powder, and raw material powder No. 1 was used as the second powder, and these were mixed. In this way, a soft magnetic powder was obtained. The mixing conditions for the first powder and the second powder are as shown in Table 2.

[0095] 8.2. Examples 2 to 17 A soft magnetic powder was obtained in the same manner as in Example 1, except that the mixing conditions for the first powder and the second powder were changed as shown in Table 2 or Table 3.

[0096] 8.3. Comparative Examples 1 to 4 A soft magnetic powder was obtained in the same manner as in Example 1, except that the production conditions for the soft magnetic powder were set as shown in Table 2 or Table 3.

[0097] [Table 2]

[0098] [Table 3]

[0099] 9. Evaluation of soft magnetic powder 9.1.Particle size distribution For the soft magnetic powders of each Example and Comparative Example, a volume-based particle size distribution was obtained by a laser diffraction scattering type particle size distribution measuring device. Then, a particle size distribution curve was created based on the obtained particle size distribution. Then, in Tables 4 and 5, when the obtained particle size distribution curve has a bimodal distribution, the particle size D1, particle size D2, difference D2-D1, coefficient k1, height H1, height H2, coefficient k2, height H3, and coefficient k3 are described. On the other hand, in Tables 4 and 5, when the obtained particle size distribution curve does not have a bimodal distribution, only one of the particle size D1 or particle size D2, and only one of the height H1 or height H2 are described.

[0100] Fig. 8 is a graph showing the particle size distribution curves obtained for the soft magnetic powders of Examples 1 to 5. Fig. 9 is a graph showing the particle size distribution curves obtained for the soft magnetic powders of Examples 6 to 9 and Comparative Example 2. Fig. 10 is a graph showing the particle size distribution curves obtained for the soft magnetic powders of Examples 10 to 14. In Figs. 8 to 10, the mixing ratio of the first powder to the second powder is described as, for example, 5:5.

[0101] As shown in Figures 8 to 10, 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 portion B can be controlled according to the mixing ratio.

[0102] 9.2.Magnetic loss (core loss) Using the soft magnetic powders of each Example and 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. The measurement conditions were the same as in 7.3. The measurement results are shown in Table 4 or Table 5.

[0103] 9.3.Magnetic permeability Using the soft magnetic powders of each Example and 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.

[0104] [Table 4]

[0105] [Table 5]

[0106] As is clear from Tables 4 and 5, the soft magnetic powders of each Example all had a bimodal distribution in which the particle size distribution curves satisfied the specified conditions. The compacts made from the soft magnetic powders of each Example had better magnetic permeability and core loss than the compacts made from the soft magnetic powders of each Comparative Example. From this, it is presumed that the soft magnetic powders of each Example have good packing properties and can produce compacts with low eddy current loss when used in the high frequency band. [Explanation of symbols]

[0107] 10...coil part, 11...powder magnetic core, 12...conductor, 20...coil part, 21...powder magnetic core, 22...conductor, 100...display part, 1000...magnetic element, 1100...personal computer, 1102...keyboard, 1104...main body, 1106...display unit, 1200...smartphone, 1202...operation button, 1204...earpiece, 1206...mouthpiece, 1300...digital still camera, 1302...case, 1304...light receiving unit, 1306...shutter button, 1308...memory, 1500...automobile, B...bottom part, H1...height, H2...height, H3...height, P1...first peak part, P2...second peak part, PSD...particle size distribution curve

Claims

1. The particle size distribution on a volume basis is measured using a laser diffraction scattering type particle size distribution measuring device, and the particle size distribution is The particle size distribution curve is obtained by plotting the cloth on an orthogonal coordinate system with the particle size on the horizontal axis and the relative particle amount on the vertical axis. When I drew The particle size distribution curve has a first peak portion having a maximum value at a particle size D1 [μm] and a second peak portion having a maximum value at a particle size D1 A second peak portion having a maximum value at a larger particle diameter D2 [μm], The particle diameter D1 is in the range of 1.0 μm or more and 16.0 μm or less, The particle diameter D2 is in the range of 15.0 μm or more and 50.0 μm or less, The difference D2-D1 between the particle diameter D1 and the particle diameter D2 is expressed by the following formula (A-1) and the following formula (A -2) is satisfied, When the height of the first peak portion is H1 and the height of the second peak portion is H2, The height H2 is lower than the height H1, and is expressed by the following formula (B-1) and the following formula (B-2): Fulfilling The particle size distribution curve has a minimum value at a particle size D3 located between the particle size D1 and the particle size D2. a bottom portion having When the height of the bottom portion is H3, the height H3 is calculated by the following formula (C-1) and the following formula (C-2): A soft magnetic powder characterized by satisfying formula (C-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) H3=k3×H1... (C-1) k3<0.9... (C-2)

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

3. 3. The soft magnetic powder according to claim 1, comprising two or more types of particles having different crystal structures.

4. A dust core comprising the soft magnetic powder according to any one of claims 1 to 3. 。

5. A magnetic element comprising the powder magnetic core according to claim 4.

6. An electronic device comprising the magnetic element according to claim 5 .

7. A moving body comprising the magnetic element according to claim 5 .

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