Compacted powder cores, inductors, and electronic and electrical equipment

Abstract

To provide a dust core which is suitable for a construction member of an inductor which has a good magnetic characteristic even under a magnetically severe environment and can also cope with miniaturization.SOLUTION: In a dust core containing a soft magnetic metal powder, the soft magnetic metal powder contains a plurality of crystalline substance particles and a plurality of amorphous substance particles. A median size D50c of the plurality of crystalline substance particles is 1.3 μm or less, and a median size D50a of the plurality of amorphous substance particles is 2.0 μm or more and 12.0 μm or less. Each of the crystalline substance particles includes a composition containing Fe and Ni. A median size D50 of the soft magnetic metal powder is calculated from the following formula (1), and is 1.8 μm or more and 7.0 μm or less: D50=(Rc×D50c+Ra×D50a) / 100 (1). Here, Rc is a mass ratio (unit: mass%) of the plurality of crystalline substance particles to the soft magnetic metal powder, and Ra is a mass ratio (unit: mass%) of the plurality of amorphous substance particles to the soft magnetic metal powder.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a compacted powder core, an inductor comprising such a compacted powder core, and an electronic or electrical device on which such inductor is mounted. In this specification, “inductor” means a passive element comprising a core material including a compacted powder core and a coil. [Background technology]

[0002] In electronic devices, there is a growing demand for miniaturization, weight reduction, and high performance. To meet these demands, switching power supply circuits within electronic devices need to be able to handle high frequencies. Therefore, inductors incorporated into switching power supply circuits must also be able to drive stably at high frequencies.

[0003] In recent years, there has been a particularly high demand for miniaturization in switching power supply circuits, especially DC-DC converters, incorporated into electronic devices such as smartphones, tablets, and laptops. As a result of meeting this demand, the inductors incorporated inside these circuits are becoming smaller while still handling large DC currents. Therefore, the magnetic environment in which the magnetic materials constituting the inductor are placed is one in which an induced magnetic field caused by this DC current is applied as a bias, and a fluctuating magnetic field caused by current fluctuations (ripple current) due to high-frequency switching is further applied. Consequently, the magnetic components constituting the inductor are required to have appropriate magnetic properties (e.g., high relative permeability, high DC superimposed current rating, and low iron loss) in such a magnetically harsh environment. Here, high relative permeability means that the inductance can be easily increased, a high DC superimposed current rating means that miniaturization is easy, and low iron loss means that power efficiency can be easily increased.

[0004] To meet these requirements, a type of compacted core, which is a magnetic component of an inductor, has been proposed that is made by mixing multiple types of magnetic powder (Patent Documents 1 to 4). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2010-118486 [Patent Document 2] International Publication No. 2020 / 090405 [Patent Document 3] Japanese Patent Publication No. 2020-72182 [Patent Document 4] Japanese Patent Publication No. 2022-37533 [Overview of the project] [Problems that the invention aims to solve]

[0006] In view of the current situation, the present invention aims to provide a compacted powder core suitable as a component of an inductor that has good magnetic properties even in a magnetically harsh environment and can be miniaturized, an inductor equipped with such a compacted powder core, and an electronic / electrical device on which this inductor is mounted. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides, in one embodiment, a compacted core comprising soft magnetic metal powder, wherein the soft magnetic metal powder comprises a plurality of crystalline particles and a plurality of amorphous particles, the median diameter D50c of the plurality of crystalline particles is 1.3 μm or less, the median diameter D50a of the plurality of amorphous particles is 2.0 μm or more and 12.0 μm or less, the crystalline particles have a composition containing Fe and Ni, and the median diameter D50 of the soft magnetic metal powder is calculated from the following formula (1) and is 1.8 μm or more and 7.0 μm or less. D50=(Rc×D50c+Ra×D50a) / 100 (1) Here, Rc is the mass ratio (unit: mass%) of the plurality of crystalline particles to the soft magnetic metal powder, and Ra is the mass ratio (unit: mass%) of the plurality of amorphous particles to the soft magnetic metal powder. The dust-compacted core having the above configuration can enhance the overall characteristics (μ 2 ×Isat / Pcv) of the inductor. Regarding the overall characteristics, μ is the relative initial permeability at 1 MHz, Pcv is the iron loss at 1 MHz, and Isat is the DC superposition rated current (the current value at which the self-inductance L decreases by 30% when DC is superposed).

[0008] In the above dust-compacted core, the metallic part of the amorphous particles may consist of an amorphous phase.

[0009] In the above dust-compacted core, the median diameter D50a of the plurality of amorphous particles may be 3.5 μm or more and 9.0 μm or less. The median diameter D50c of the plurality of crystalline particles may be 0.50 μm or more and 1.3 μm or less.

[0010] In the above dust-compacted core, the mass ratio Ra of the plurality of amorphous particles to the soft magnetic metal powder may be 10% by mass or more and 90% by mass or less. The mass ratio Ra of the plurality of amorphous particles to the soft magnetic metal powder may be 35% by mass or more and 85% by mass or less.

[0011] In the above dust-compacted core, the plurality of crystalline particles may have a composition containing 10% by mass or more and 90% by mass or less of Ni, with the balance being Fe and impurities.

[0012] In the above dust-compacted core, the plurality of amorphous particles may have a metallic part having a composition containing P: 5.0 to 13.0 atomic%, C: 2.2 to 13.0 atomic%, Ni: 0 to 10.0 atomic%, B: 0 to 9.0 atomic%, Si: 0 to 7.0 atomic%, Cr: 0 to 6.0 atomic%, and Sn: 0 to 3.0 atomic%, with the balance being Fe and impurities. In the above composition, Ni, B, Si, Cr, and Sn are optional addition elements.

[0013] In the compacted core described above, the plurality of amorphous particles may consist of a first particle in which the metallic portion is made up of an amorphous phase, and a second particle having a metallic portion consisting of a crystalline phase and an amorphous phase with a Scherrer diameter of 50 nm or less.

[0014] In the compacted core comprising the first and second particles described above, the mass ratio Ra2 of the second particles to the plurality of amorphous particles may be 80% by mass or less, or 1% by mass or more and 60% by mass or less.

[0015] In the compacted core comprising the first and second particles described above, the median diameter D50a1 of the first particle may be 3.5 μm or more and 9.0 μm or less. The median diameter D50a2 of the second particle may be 2.0 μm or more and 15 μm or less.

[0016] In the compacted core comprising the first and second particles described above, the median diameter D50a of the plurality of amorphous particles is calculated from the following formula (2) and may be 3.0 μm or more and 8.0 μm or less. D50a=(Ra1×D50a1+Ra2×D50a2) / 100 (2) Here, as described above, Ra1 is the mass ratio (unit: mass%) of the first particle to the plurality of amorphous particles, and Ra2 is the mass ratio (unit: mass%) of the second particle to the plurality of amorphous particles.

[0017] In the compacted core comprising the first and second particles described above, the median diameter D50c of the plurality of crystalline particles may be 0.5 μm or more and 1.3 μm or less. The mass ratio Ra of the plurality of amorphous particles to the soft magnetic metal powder may be 10% by mass or more and 90% by mass or less, or 35% by mass or more and 60% by mass or less.

[0018] In the compacted core comprising the first and second particles described above, the plurality of crystalline particles may have a metallic portion having a composition consisting of 10% by mass or more and 90% by mass or less of Ni, with the remainder being Fe and impurities.

[0019] In the compacted core comprising the first and second particles described above, the plurality of amorphous particles may have a metallic portion with a composition containing P: 5.0-13.0 atomic%, C: 2.2-13.0 atomic%, Ni: 0-10.0 atomic%, B: 0-9.0 atomic%, Si: 0-7.0 atomic%, Cr: 0-6.0 atomic%, and Sn: 0-3.0 atomic%, with the remainder being Fe and impurities. In the above composition, Ni, B, Si, Cr, and Sn are optional additive elements.

[0020] In the compacted core comprising the first and second particles described above, the second particle may have a composition comprising one or more elements X selected from the group consisting of C, B, P, and Si: 5 atomic% to 20 atomic%; one or more elements M selected from the group consisting of Mo, Nb, Cu, Zr, Al, and V: 1 atomic% to 10 atomic%; and the remainder being Fe and impurities.

[0021] In the compacted core described above, the D50a of the plurality of amorphous particles is 3.5 μm or more and 9.0 μm or less, the D50c of the plurality of crystalline particles is 0.50 μm or more and 1.3 μm or less, the mass ratio Ra of the plurality of amorphous particles to the soft magnetic metal powder is 35 mass% or more and 60 mass% or less, and the plurality of amorphous particles have a composition containing P: 5.0 to 13.0 atomic%, C: 2.2 to 13.0 atomic%, Ni: 0 to 10.0 atomic%, B: 0 to 9.0 atomic%, Si: 0 to 7.0 atomic%, Cr: 0 to 6.0 atomic%, and Sn: 0 to 3.0 atomic%, with the remainder being Fe and impurities, and may have a metallic portion consisting of an amorphous phase. In the above composition, Ni, B, Si, Cr, and Sn are optional additive elements.

[0022] The above compacted core, when measured under conditions of a frequency of 1 MHz and an effective maximum magnetic flux density Bm of 15 mT, exhibited an iron loss Pcv of 70 kW. -1 m 3The following may also be true: A compacted core according to another aspect of the present invention comprises soft magnetic metal powder, wherein the soft magnetic metal powder comprises a plurality of crystalline particles and a plurality of amorphous particles, and when a cross-section of the compacted core is observed, it may have the following characteristics: The average equivalent circular diameter of the plurality of crystalline particles is 1.0 μm or less. The average equivalent diameter of the plurality of amorphous particles is 1.0 μm or more and 8.0 μm or less, The ratio of the cross-sectional area occupied by the plurality of amorphous particles in the observation field to the cross-sectional area occupied by the soft magnetic metal powder in the observation field is 30% or more and 70% or less.

[0023] In another aspect of the present invention, an inductor is provided comprising a connection terminal, a conductor electrically connected to the connection terminal and capable of generating an induced magnetic field by energization, and the powder core described above. In such an inductor, the powder core is positioned at a location through which the magnetic field lines of the induced magnetic field from the conductor pass.

[0024] In another aspect, the present invention provides an electronic / electrical device on which an inductor according to the above-described aspect of the present invention is mounted. In this electronic / electrical device, the inductor is connected to a circuit board via a connection terminal. The circuit into which the inductor is incorporated in the above-described electronic / electrical device is not particularly limited, but when used in a switching power supply circuit such as a DC-DC converter, the advantages of the above-described inductor, which has excellent DC superposition characteristics, can be easily utilized. Furthermore, when the electronic / electrical device is a portable device such as a smartphone, the advantages of the above-described inductor, which is small and low-profile, can be easily utilized. [Effects of the Invention]

[0025] According to the above invention, a compacted powder core suitable as a component of an inductor that has good magnetic properties even in a magnetically harsh environment and can be miniaturized, an inductor equipped with such a compacted powder core, and an electronic / electrical device on which this inductor is mounted are provided. [Brief explanation of the drawing]

[0026] [Figure 1] This is a conceptual perspective view showing the shape of a compacted core according to one embodiment of the present invention. [Figure 2] This diagram conceptually illustrates a spray dryer device and its operation used in an example of a method for manufacturing granulated powder. [Figure 3] This is a conceptual perspective view showing the shape of a toroidal coil, which is a type of inductor equipped with a compacted powder core according to one embodiment of the present invention. [Figure 4] This is a conceptual perspective view showing the shape of a coil-embedded inductor, which is a type of inductor equipped with a compacted powder core according to one embodiment of the present invention. [Figure 5] This graph illustrates the characteristics of an inductor equipped with a powder-compacted core according to one embodiment of the present invention. [Figure 6] This figure illustrates the relationship between the characteristics of an inductor equipped with a compacted powder core according to one embodiment of the present invention and the median diameter D50. [Figure 7] This graph shows the results presented in Examples 26 to 29. [Figure 8] This graph shows the results presented in Examples 30 to 33. [Figure 9] This figure shows a secondary electron image of the cross-section of the compacted core according to Example 5-3. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described in detail below. 1. Flour core (1) Overview The compacted core 1 according to one embodiment of the present invention shown in Figure 1 is a toroidal core with a ring-shaped appearance and contains soft magnetic metal powder. The soft magnetic metal powder contains multiple types, specifically multiple crystalline particles and multiple amorphous particles. For each of these multiple types of metal powder, when the median diameter (unit: μm) is determined, which is the particle size at which the cumulative particle size distribution from the smallest particle size side accounts for 50% of the volume-based particle size distribution measured by laser diffraction-scattering, the median diameter D50c for the multiple crystalline particles is 1.3 μm or less, and the median diameter D50a for the multiple amorphous particles is 2.0 μm or more and 12.0 μm or less. The median diameter D50 of the soft magnetic metal powder containing these multiple types of particles can be approximately calculated from the following formula (1) and is 1.8 μm or more and 7.0 μm or less: D50=(Rc×D50c+Ra×D50a) / 100 (1)

[0028] Here, Rc is the mass ratio (unit: mass%) of multiple crystalline particles to the soft magnetic metal powder, and Ra is the mass ratio (unit: mass%) of multiple amorphous particles to the soft magnetic metal powder.

[0029] The compacted core 1 according to this embodiment has a low initial permeability (relative initial permeability μ), low iron loss Pcv, and excellent DC superposition characteristics because the soft magnetic metal powder satisfies the above-mentioned particle size conditions, and furthermore, the multiple crystalline particles satisfy the compositional conditions described later (containing Fe and Ni). In this specification, the DC superposition characteristics are evaluated by the DC superposition rated current Isat (the current value at which the self-inductance L of the inductor decreases by 30% when DC is superimposed). Specifically, the DC superposition rated current Isat is a value measured by passing current through an inductor having a toroidal core with an outer diameter of 20 mm, an inner diameter of 12.7 mm, and a height of 3.1 mm, on which 34 turns of winding are applied. The compacted core 1 according to this embodiment and the inductor equipped therewith have excellent overall characteristics (μ) due to the appropriateness of the above characteristics. 2 It has ×Isat / Pcv. Therefore, the inductor equipped with the compacted core 1 according to this embodiment exhibits excellent characteristics even under magnetically harsh conditions such as high current, and can be miniaturized.

[0030] (2) Crystalline particles The compacted core 1 according to this embodiment contains a plurality of soft magnetic particles (crystalline particles) that include a crystalline phase. In this specification, "crystalline" means that a diffraction spectrum with a clear peak that allows the material type to be identified can be obtained by general X-ray diffraction measurement.

[0031] As described above, the median diameter D50c of the multiple crystalline particles is 1.3 μm or less. By reducing the median diameter D50c in this way, a reduction in the iron loss Pcv of the compacted core 1 and an improvement in the DC superposition characteristics of the inductor equipped with the compacted core 1 are achieved. From the viewpoint of appropriate handling, appropriate availability, and improved magnetic properties, it may be preferable that the median diameter D50c of the multiple crystalline particles be between 0.50 μm and 1.0 μm.

[0032] The particle sizes of multiple crystalline particles can also be obtained by analyzing an image (secondary electron image) obtained by imaging the cross-section of the compacted core 1 with a scanning electron microscope. In this case, the average equivalent circular diameter of the multiple crystalline particles in the observation field should be 1.0 μm or less, and preferably between 0.3 μm and 0.7 μm. As explained in the examples, the average equivalent circular diameter of the particles obtained from the secondary electron image is obtained as a value of approximately 60-70% (63% in the examples) of the median diameter of the particle size distribution measured by laser diffraction-scattering.

[0033] The mass ratio Rc of multiple crystalline particles to soft magnetic metal powder is preferably 10% by mass or more and 90% by mass or less, and more preferably 10% by mass or more and less than 50% by mass. Since the multiple crystalline particles are softer than the multiple amorphous particles and deform to fill the spaces between the multiple amorphous particles in the compacted core 1, a mass ratio Rc < mass ratio Ra makes it possible to increase the core density in the inductor equipped with the compacted core 1, and the DC superposition characteristics do not deteriorate easily.

[0034] The composition of the multiple crystalline particles includes Fe and Ni, preferably Fe and Ni. In a compacted core 1 having such a composition, the iron loss Pcv is lower compared to cases where the composition of the multiple crystalline particles includes other elements instead of Ni, such as Si or Cr, and the DC superposition characteristics of the inductor equipped with the compacted core 1 tend to be good. In particular, when the composition of the multiple crystalline particles consists of Fe and Ni, the iron loss Pcv can be reduced by lowering the annealing temperature during the annealing process in the manufacturing of the compacted core 1. When the composition consists of Fe, Si, and Cr, this tendency is not observed; rather, the opposite tendency is observed (iron loss Pcv increases as the annealing temperature decreases).

[0035] From the viewpoint of enhancing the magnetic properties of multiple crystalline particles, the composition of the multiple crystalline particles is more preferably composed of 10% to 90% by mass of Ni, with the remainder being Fe and impurities, and is particularly preferably composed of 40% to 60% by mass of Ni.

[0036] Furthermore, it is preferable that the metallic portion of the multiple crystalline particles substantially does not contain amorphous phase. In this case, the DSC curve obtained by differential thermal analysis does not contain a peak indicating crystallization, i.e., a peak of exothermic reaction associated with the phase change from amorphous to crystalline phase. The structure of the multiple crystalline particles may consist of crystalline phase.

[0037] (3) Amorphous particles The compacted core 1 according to this embodiment contains a plurality of particles (amorphous particles) that are soft magnetic and include an amorphous phase. In this specification, "amorphous" means satisfying at least one of the following conditions: (A) the diffraction spectrum obtained by a general X-ray diffraction method includes a broad peak, and (B) the DSC curve obtained by differential thermal analysis includes a peak indicating crystallization, i.e., an exothermic peak associated with the phase change from the amorphous phase to the crystalline phase. The metallic portion of the plurality of amorphous particles may consist only of the amorphous phase, or it may have both an amorphous phase and a crystalline phase.

[0038] The median diameter D50a of the multiple amorphous particles is between 2.0 μm and 12.0 μm, as described above. Having the median diameter D50a within this range reduces the iron loss Pcv of the compacted core 1. From the viewpoint of appropriate handling, availability, and improved magnetic properties, it may be preferable for the median diameter D50a to be between 3.5 μm and 9.0 μm.

[0039] The particle sizes of the multiple amorphous particles can also be obtained by analyzing the image (secondary electron image) obtained by imaging the cross-section of the compacted core 1 with a scanning electron microscope. In this case, the average equivalent circular diameter of the multiple amorphous particles in the observation field should be between 1.0 μm and 8.5 μm, and preferably between 2.0 μm and 6.5 μm.

[0040] The mass ratio Ra of multiple amorphous particles to soft magnetic metal powder is preferably 10% by mass or more and 90% by mass or less, and may be more preferably 30% by mass or more and less than 85% by mass, from the viewpoint of more stably reducing iron loss Pcv and more stably improving DC superposition characteristics in an inductor equipped with a compacted powder core 1.

[0041] One example of a case where the metallic portion of amorphous particles is substantially composed of an amorphous phase (amorphous single-phase particles, first particle) is when the metallic portion of the amorphous particles has a composition containing B or P.

[0042] For example, the metallic portion of amorphous particles may be composed of an Fe-PC alloy. The composition of the Fe-PC alloy may consist of 1.0 to 13.0 atomic percent of P, 1.0 to 13.0 atomic percent of C, Fe, and impurities. This Fe-PC alloy may also contain one or more elements selected from the group consisting of Ni, Sn, Cr, B, and Si. In this case, for example, the amount of Ni may be 0 to 10.0 atomic percent, the amount of Sn may be 0 to 3.0 atomic percent, the amount of Cr may be 0 to 6.0 atomic percent, the amount of B may be 0 to 9.0 atomic percent, and the amount of Si may be 0 to 7.0 atomic percent. The amount of Fe is preferably 65 atomic percent or more.

[0043] Specific examples of Fe-PC alloys include those with the following compositions: P: 5.0 atomic% or more and 13.0 atomic% or less C: 2.2 atomic% or more and 13.0 atomic% or less Ni: 10.0 atomic% or less B: 9.0 atomic% or less Si: 7.0 atomic% or less Cr: 6.0 atomic% or less Sn: 3.0 atomic% or less It contains [a certain substance], with the remainder being Fe and impurities. In the above composition, Ni, B, Si, Cr, and Sn are arbitrary elements. Therefore, the lower limit of the amount of these arbitrary elements is 0 atomic percent.

[0044] Furthermore, for example, the metallic portion of the amorphous particles may be composed of an Fe-BC alloy. Specific examples of this Fe-BC alloy include those with the following compositions: B: 5.0 atomic% or more and 16.0 atomic% or less C: 2.0 atomic% or more and 10.0 atomic% or less Si: 12.0 atomic% or less Ni: 10.0 atomic% or less Cr: 6.0 atomic% or less Sn: 3.0 atomic% or less It contains [a certain substance], with the remainder being Fe and impurities. In the above composition, Ni, B, Si, Cr, and Sn are arbitrary elements. Therefore, the lower limit of the amount of these arbitrary elements is 0 atomic percent. In this case, it is preferable that the amount of C is 5.0 atomic percent or more.

[0045] One example of a case where multiple amorphous particles have both an amorphous phase and a crystalline phase is when the multiple amorphous particles are nanocrystalline particles (second particles) having a metallic portion containing a crystalline phase with a Scherrer diameter of 50 nm or less. This metallic portion may consist of a crystalline phase with a Scherrer diameter of 50 nm or less and an amorphous phase surrounding the crystalline phase.

[0046] As an example without limitation, the second particle may have a composition containing one or more elements X selected from the group consisting of C, B, P, and Si: 5 to 20 atomic percent, one or more elements M selected from the group consisting of Mo, Nb, Cu, Zr, Al, and V: 1 to 10 atomic percent, with the remainder being Fe and impurities. In this case, a crystalline phase with a Scherrer diameter of 50 nm or less is likely to form.

[0047] A specific example of the second type of particle is one in which the metallic portion is composed of an Fe-Si-B-Nb-Cu alloy. The Fe-Si-B-Nb-Cu alloy may consist of 1.0 to 16.0 atomic percent of Si, 1.0 to 15.0 atomic percent of B, 0.50 to 8.0 atomic percent of Nb, 0.50 to 5.0 atomic percent of Cu, and the remainder consisting of Fe and impurities. In this case, the amount of Fe is preferably 65 atomic percent or more.

[0048] Another example of a case where multiple amorphous particles have both an amorphous phase and a crystalline phase is when the multiple amorphous particles are a mixture of the first and second particles described above.

[0049] In the above mixed particles, at least one of the following conditions may be met: (a) the mass ratio Ra2 of the second particle to the plurality of amorphous particles is 80% by mass or less, and (b) the mass ratio Ra2 of the second particle to the plurality of amorphous particles is 1% by mass or more and 60% by mass or less.

[0050] In the above mixed particles, at least one of the following conditions may be met: (c) the median diameter D50a1 of the first particle is 3.5 μm or more and 9.0 μm or less; and (d) the median diameter D50a2 of the second particle is 2.0 μm or more and 15.0 μm or less.

[0051] In the above mixed particles, the median diameter D50a of multiple amorphous particles may be calculated as an approximate value from the following formula (2), and the calculated median diameter D50a may be between 3.0 μm and 8.0 μm. D50a=(Ra1×D50a1+Ra2×D50a2) / 100 (2)

[0052] Furthermore, the metallic portion of the first particle may include a crystalline phase that inevitably occurs during the process.

[0053] (4) Soft magnetic powder The median diameter D50 of the soft magnetic metal powder contained in the compacted core 1 according to one embodiment of the present invention can be approximately calculated from the following formula (1) and is between 1.8 μm and 7.0 μm. D50=(Rc×D50c+Ra×D50a) / 100 (1)

[0054] The median diameter D50 being within this range results in excellent overall characteristics (μ 2 An inductor having ×Isat / Pcv can be provided. From the viewpoint of more stably improving the overall characteristics, the median diameter D50 may preferably be 2.0 μm or more and 5.0 μm or less, and more preferably 2.5 μm or more and 4.0 μm or less.

[0055] The particle size of the soft magnetic powder can also be determined by analyzing an image (secondary electron image) obtained by imaging the cross-section of the compacted core 1 with a scanning electron microscope. In this case, the ratio of the occupied cross-sectional area of ​​the multiple amorphous particles in the observation field to the occupied cross-sectional area of ​​the soft magnetic metal powder in the observation field should be between 30% and 70%, and preferably between 40% and 60%.

[0056] The shape of the soft magnetic powder is not limited. The soft magnetic powder may be spherical, elliptical, flaky, or have an irregular shape. The manufacturing method for obtaining these shapes is also not limited.

[0057] The soft magnetic powder may be subjected to a surface insulation treatment. When the soft magnetic powder is subjected to a surface insulation treatment, the insulation resistance of the compacted powder core 1 is improved. The type of surface insulation treatment applied to the soft magnetic powder is not limited. Examples include phosphoric acid treatment, phosphate treatment, and oxidation treatment. The soft magnetic powder may have an insulating film on its surface. This insulating film may contain at least one selected from the group consisting of Si, P, and B, and O (oxygen).

[0058] (5) Other materials The compacted core 1 according to one embodiment of the present invention may further contain optional auxiliary materials in addition to the soft magnetic powder. These optional auxiliary materials may be, for example, binders or modifiers. The binders bind together the particles, such as magnetic powder, contained in the compacted core 1. The binders are preferably insulating materials in order to impart insulation resistance to the compacted core 1.

[0059] The binder may be an organic or inorganic material. The organic material may be a resin material. Examples of resin materials include acrylic resin, silicone resin, epoxy resin, phenolic resin, urea resin, melamine resin, and polyester resin. The inorganic material may be a glass-based material such as water glass. The binder may be a product of a reaction such as thermal decomposition, or it may be a mixture of multiple materials.

[0060] Modifiers, for example, improve the fluidity of powders or adjust the hardening rate of binders. The modifier may also be a glass-based material.

[0061] (6) Iron loss Pcv The iron loss Pcv of the compacted core 1 according to this embodiment was measured at a frequency of 1 MHz and an effective maximum magnetic flux density Bm of 15 mT, resulting in a value of 70 kW. -1 m 3 The following is preferable. Having the iron loss Pcv of the powder core 1 within this range makes it easier to stably improve the overall characteristics of the inductor equipped with the powder core 1. From the viewpoint of more stably improving the overall characteristics of the inductor, the iron loss Pcv of the powder core 1 should be 60kW when measured under the above conditions. -1m 3 is preferably as follows, 55 kW -1 m 3 is more preferably as follows.

[0062] 2. Method for manufacturing the compacted core The method for manufacturing the compacted core 1 according to one embodiment of the present invention is not particularly limited, but if the manufacturing method described below is adopted, it is possible to more efficiently manufacture the compacted core 1.

[0063] The method for manufacturing the compacted core 1 according to one embodiment of the present invention includes a molding step described below, and may further include a heat treatment step.

[0064] (1) Molding step First, prepare a mixture containing magnetic powder and a component that provides a binding component in the compacted core 1. The component that provides the binding component (also referred to as the "binder component" in this specification) may be the binder component itself or a material different from the binder component. As a specific example of the latter, there is a case where the binder component is a resin material and the binding component is its thermal decomposition residue. Such a thermal decomposition residue can be formed by a heat treatment step performed subsequent to the molding step, as described below.

[0065] A molded product can be obtained by a molding process including pressure molding of this mixture. The pressure conditions are not limited and are appropriately set based on the composition of the binder component and the like. For example, when the binder component is made of a thermosetting resin, it is preferable to heat together with pressurization to advance the curing reaction of the resin in the mold. On the other hand, in the case of compression molding with a high pressure, heating is not a necessary condition, and the pressurization is for a short time. The pressure in the case of compression molding is appropriately set. By way of non-limiting illustration, it is 0.5 GPa or more and 2 GPa or less, and may preferably be 1 GPa or more and 2 GPa or less.

[0066] The following will explain in more detail the case where the mixture is granulated powder and compression molding is performed. Because granulated powder has excellent handling properties, it can improve the workability of the compression molding process, which has a short molding time and excellent productivity.

[0067] (1-1) Granulated flour The granulated powder contains magnetic powder and a binder component. The amount of the binder component in the granulated powder is not particularly limited. If the amount is excessively low, the binder component will have difficulty holding the magnetic powder. Also, if the amount of the binder component is excessively low, the binding component consisting of the thermal decomposition residue of the binder component in the compacted core 1 obtained through the heat treatment process will have difficulty insulating the multiple magnetic powders from each other. On the other hand, if the amount of the binder component is excessively high, the amount of binding component contained in the compacted core 1 obtained through the heat treatment process tends to be high. If the amount of binding component in the compacted core 1 is high, the magnetic properties of the compacted core 1 tend to deteriorate. Therefore, it is preferable that the amount of the binder component in the granulated powder be 0.5% by mass or more and 5.0% by mass or less of the total amount of granulated powder. From the viewpoint of more stably reducing the possibility of deterioration in the magnetic properties of the compacted core 1, it is preferable that the amount of binder component in the granulated powder be 1.0% by mass or more and 3.5% by mass or less of the total granulated powder, and more preferably 1.2% by mass or more and 3.0% by mass or less.

[0068] The granulated powder may contain materials other than the magnetic powder and binder components mentioned above. Examples of such materials include lubricants, silane coupling agents, and insulating fillers. When a lubricant is included, its type is not particularly limited. It may be an organic lubricant or an inorganic lubricant. Specific examples of organic lubricants include metal soaps such as zinc stearate and aluminum stearate. These organic lubricants are thought to vaporize during the heat treatment process and hardly remain in the compacted core 1.

[0069] The method for producing granulated powder is not particularly limited. The components that give granulated powder may be kneaded as is, and the resulting kneaded product may be pulverized by a known method to obtain granulated powder. Alternatively, a slurry may be prepared by adding a dispersion medium (water is one example) to the above components, and granulated powder may be obtained by drying and pulverizing this slurry. The particle size distribution of the granulated powder may be controlled by sieving or classification after pulverization.

[0070] One example of a method for obtaining granulated powder from the slurry described above is the use of a spray dryer. As shown in Figure 2, a rotor 201 is provided inside the spray dryer device 200, and slurry S is injected from the top of the device toward the rotor 201. The rotor 201 rotates at a predetermined speed, and the slurry S is sprayed into droplets by centrifugal force in the chamber inside the spray dryer device 200. Furthermore, hot air is introduced into the chamber inside the spray dryer device 200, thereby volatilizing the dispersion medium (water) contained in the droplet-shaped slurry S while maintaining its droplet shape. As a result, granulated powder P is formed from the slurry S. This granulated powder P is collected from the bottom of the spray dryer device 200. The rotation speed of the rotor 201, the temperature of the hot air introduced into the spray dryer device 200, the temperature at the bottom of the chamber, and other parameters can be set as appropriate. Specific examples of parameter settings include a rotational speed of 4000-8000 rpm for the rotor 201, a hot air temperature of 100-170°C for the spray dryer device 200, and a temperature of 80-90°C for the bottom of the chamber. The atmosphere and pressure inside the chamber can also be set as appropriate. For example, the chamber can be set to an air atmosphere with a pressure difference of 2 mmH2O (approximately 0.02 kPa) from atmospheric pressure. The particle size distribution of the obtained granulated powder P may be further controlled by sieving or other methods.

[0071] (1-2) Pressurization conditions The pressurizing conditions in compression molding are not particularly limited. They should be set appropriately considering the composition of the granulated powder, the shape of the molded product, etc. If the pressurizing force when compressing the granulated powder is excessively low, the mechanical strength of the molded product will decrease. This can lead to problems such as reduced handling of the molded product and reduced mechanical strength of the compacted core 1 obtained from the molded product. In addition, the magnetic properties or insulating properties of the compacted core 1 may decrease. On the other hand, if the pressurizing force when compressing the granulated powder is excessively high, it becomes difficult to manufacture a molding die that can withstand that pressure. From the viewpoint of more stably reducing the possibility that the compression process adversely affects the mechanical and magnetic properties of the compacted core 1 and facilitating mass industrial production, the pressurizing force when compressing the granulated powder is preferably 0.3 GPa or more and 2 GPa or less, more preferably 0.5 GPa or more and 2 GPa or less, and particularly preferably 0.8 GPa or more and 2 GPa or less.

[0072] In compression molding, pressure may be applied while heating, or pressure may be applied at room temperature.

[0073] (2) Heat treatment process The molded product obtained by the molding process may be the compacted core 1 according to this embodiment, or the compacted core 1 may be obtained by performing a heat treatment process on the molded product as described below.

[0074] In the heat treatment process, the molded product obtained in the molding process is heated to adjust the magnetic properties by correcting the distance between the magnetic powders and to relieve the strain applied to the magnetic powders in the molding process, thereby obtaining the compacted powder core 1.

[0075] As the purpose of the heat treatment process is to adjust the magnetic properties of the compacted core 1, the heat treatment conditions, such as the heat treatment temperature, are set to the extent that the magnetic properties of the compacted core 1 are optimal. One example of a method for setting the heat treatment conditions is to vary the maximum heating temperature (annealing temperature) of the molded product while keeping other conditions such as the heating rate and the holding time at the heating temperature constant.

[0076] The criteria for evaluating the magnetic properties of the compacted core 1 when setting heat treatment conditions are not particularly limited. A specific example of an evaluation item is the iron loss Pcv of the compacted core 1. In this case, the heating temperature of the molded product should be set so that the iron loss Pcv of the compacted core 1 is minimized. As will be described later, in this embodiment, the compacted core 1 tends to have a lower iron loss Pcv as the annealing temperature decreases in the range of 325°C to 400°C.

[0077] The atmosphere during heat treatment is not particularly limited. In the case of an oxidizing atmosphere, there is a higher possibility of excessive thermal decomposition of the binder component and oxidation of the magnetic powder, so it is preferable to perform heat treatment in an inert atmosphere such as nitrogen or argon, or a reducing atmosphere such as hydrogen. If the binder component is formed of a resin material, this binder component may become a thermal decomposition residue after the heat treatment described above. It is conceivable that the binder component becomes a thermal decomposition residue when the strain is relieved as described above.

[0078] 3. Inductors, electronic and electrical equipment An inductor according to one embodiment of the present invention comprises a connection terminal for electrically connecting to a substrate or the like, a conductor electrically connected to the connection terminal and capable of generating an induced magnetic field when energized, and a powder core 1 according to the above embodiment of the present invention. In the inductor, the powder core 1 is positioned where the magnetic field lines of the induced magnetic field from the conductor pass through. Since the inductor according to one embodiment of the present invention comprises the powder core 1 according to the above embodiment of the present invention, the overall characteristics (μ 2 Excellent in ×Isat / Pcv.

[0079] In this specification, the overall characteristics are determined by the relative initial permeability μ at 1 MHz, the iron loss Pcv at 1 MHz, and the DC superimposed rated current Isat. High self-inductance L and high DC superimposed rated current Isat are required as product characteristics for inductors. Since self-inductance L is proportional to relative initial permeability μ, μ × Isat is one of the indicators for evaluating the characteristics of an inductor. Here, even with the same composition, μ × Isat changes depending on the value of the relative initial permeability μ. Therefore, when comparing with the same relative initial permeability μ, a higher μ × Isat indicates that the inductor has superior characteristics. Another indicator, separate from the above, is a low iron loss Pcv of the compacted core 1.

[0080] Therefore, when the measurement results of the inductor (and the compacted powder core 1 constituting it) are plotted with μ × Isat on the vertical axis and μ / Pcv on the horizontal axis, the higher up the resulting graph is, the better the inductor (and the compacted powder core 1 constituting it) is. Figure 5 is a graph illustrating the characteristics of an inductor equipped with a compacted powder core 1 according to one embodiment of the present invention, and plots an inductor equipped with a compacted powder core 1 according to one embodiment of the present invention (inventive example) and an inductor equipped with a compacted powder core other than the compacted powder core 1 according to one embodiment of the present invention (comparative example). In Figure 5, the dashed lines represent μ 2 ×Isat / Pcv=380mA·kW -1 m 3 and μ 2 ×Isat / Pcv = 420mA·kW -1 m 3 This indicates that approximately μ 2 ×Isat / Pcv is 400mA·kW -1 m 3 To a certain extent, a boundary area exists that distinguishes between inventive examples and comparative examples.

[0081] Figure 6 illustrates the relationship between the characteristics of an inductor equipped with a compacted powder core according to one embodiment of the present invention and the median diameter D50. Figure 6 shows the results used to plot the graph in Figure 5, with the overall characteristic (μ) on the vertical axis. 2The graph shows the median diameter D50 of the compacted core 1 on the horizontal axis (×Isat / Pcv). It is confirmed that the inventive example is located in the median diameter D50 range of 1.8 μm to 7.0 μm.

[0082] An example of an inductor is the toroidal coil 10 shown in Figure 3. The toroidal coil 10 comprises a coil 2a formed by winding a coated conductive wire 2 around a ring-shaped compacted core (toroidal core) 1. The ends 2d and 2e of the coil 2a can be defined in the portion of the conductive wire located between the coil 2a, which consists of the wound coated conductive wire 2, and the ends 2b and 2c of the coated conductive wire 2. Thus, in this embodiment, the components constituting the coil and the components constituting the connection terminals may be made of the same material.

[0083] Another example of an inductor according to one embodiment of the present invention is the coil-embedded inductor 20 shown in Figure 4. The coil-embedded inductor 20 can be formed in a small chip shape of a few millimeters square and comprises a box-shaped powder core 21, in which the coil portion 22c of a coated conductive wire 22 is embedded. The conductor of the coil portion 22c generates an induced magnetic field when energized, and the magnetic field lines of this induced magnetic field pass through the powder core 21. The ends 22a and 22b of the coated conductive wire 22 are located on the surface of the powder core 21 and are exposed. Part of the surface of the powder core 21 is covered by electrically independent connecting ends 23a and 23b. Connecting end 23a is electrically connected to end 22a of the coated conductive wire 22, and connecting end 23b is electrically connected to end 22b of the coated conductive wire 22. In the coil-embedded inductor 20 shown in Figure 4, the end 22a of the insulated conductive wire 22 is covered by the connecting end 23a, and the end 22b of the insulated conductive wire 22 is covered by the connecting end 23b.

[0084] The method of embedding the coil portion 22c of the coated conductive wire 22 into the compacted core 21 is not limited. A member with the coated conductive wire 22 wound around it may be placed in a mold, and a mixture (granulated powder) containing magnetic powder may be supplied to the mold to perform pressure molding. Alternatively, multiple members made by pre-molding a mixture (granulated powder) containing magnetic powder may be prepared in advance, these members may be combined, and the coated conductive wire 22 may be placed in the voids formed at that time to obtain an assembly, which may then be pressure molded. The material of the coated conductive wire 22 including the coil portion 22c is not limited. For example, it may be copper or a copper alloy. The coil portion 22c may be an edgewise coil. The material of the connecting ends 23a and 23b is also not limited. From the viewpoint of superior productivity, it may be preferable to have a metallized layer formed from a conductive paste such as silver paste and a plating layer formed on this metallized layer. The material for forming this plating layer is not limited. Examples of metallic elements contained in the material include copper, aluminum, zinc, nickel, iron, and tin.

[0085] An electronic / electrical device according to one embodiment of the present invention is an electronic / electrical device on which an inductor according to the above embodiment of the present invention is mounted, wherein the inductor is connected to a circuit board at its connection terminals. An example of a circuit equipped with such an inductor is a switching power supply circuit such as a DC-DC converter. Switching power supply circuits tend to have a higher switching frequency and an increased amount of current flowing through the circuit in order to meet various demands such as miniaturization, weight reduction, and increased functionality of electronic / electrical devices. For this reason, the current flowing through the inductor, which is a component of the circuit, also tends to have a higher fluctuating frequency and an increased average current.

[0086] In this regard, as described above, the compacted powder core 1 according to one embodiment of the present invention has excellent DC superposition characteristics, so an inductor equipped with this compacted powder core 1 can operate appropriately in a high magnetic field environment. Moreover, because the iron loss Pcv of the compacted powder core 1 is low in the inductor according to one embodiment of the present invention, the decrease in efficiency is suppressed in a switching power supply circuit equipped with such an inductor, and the problem of heat generation is less likely to occur. Thus, electronic and electrical equipment on which the inductor according to one embodiment of the present invention is mounted can be made smaller and lighter while achieving high functionality.

[0087] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. Accordingly, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. [Examples]

[0088] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples. (Examples 1-1 to 33)

[0089] (1) Preparation of magnetic powder Three types of crystalline particles (commercially available) with different median diameters (D50c) were prepared, consisting of an Fe-Ni alloy with a Ni content of 50% by mass and the remainder being Fe and impurities, where the metallic portion is a crystalline phase. No insulating surface treatment was applied to these crystalline particles.

[0090] Crystalline particles (median diameter D50c: 2.0 μm) were prepared (commercially available) consisting of an Fe-Si-Cr alloy with a Si content of 3.5 mass% and a Cr content of 4.5 mass% and the remainder being Fe and impurities, with the metallic portion being the crystalline phase. No insulating surface treatment was applied to these crystalline particles.

[0091] Fe-PC alloys were prepared by weighing raw materials containing the elements Fe, Ni, Cr, P, C, and B to achieve a predetermined composition. Five types of particles (5.5 μm, 6.5 μm, 8.0 μm, 11.0 μm, 12.0 μm) with different median diameters D50a1, all consisting of amorphous metallic phases, were then prepared from the resulting Fe-PC alloy using methods such as water atomization. The chemical composition of the obtained first particles consisted of 6 atomic% Ni, 2 atomic% Cr, 11 atomic% P, 8 atomic% C, 2 atomic% B, with the remainder being Fe and impurities. No insulating surface treatment was applied to these first particles.

[0092] Second particles were prepared (commercially available) that contain the elements Fe, Si, B, Nb, and Cu, and have a metallic portion consisting of a crystalline phase and an amorphous phase with a Scherrer diameter of 50 nm or less, and have different median diameters D50a2 (four types: 4.0 μm, 11 μm, 15 μm, and 27 μm). These second particles were subjected to an insulating coating treatment on their surface.

[0093] The particle size distributions of the prepared crystalline powder (crystalline particles), amorphous single-phase powder (first particles), and nanocrystalline powder (second particles) were measured as volume distributions using a laser diffraction / scattering particle size analyzer (Nikkiso Co., Ltd. "Microtrac Particle Size Distribution Analyzer MT3300EX"). The particle size (median diameter, unit: μm) at which the cumulative particle size distribution from the smallest particle size side accounts for 50% of the volume-based particle size distribution was determined.

[0094] (2) Preparation of granulated powder As shown in Tables 1 to 4, two or three types were selected from the first particles, second particles, and crystalline particles described above, and mixed in the predetermined proportions shown in each table to obtain magnetic powder, and the median diameter D50 was determined. The calculated median diameter D50 (unit: μm) is shown in Tables 1 to 4.

[0095] [Table 1]

[0096] [Table 2]

[0097] [Table 3]

[0098] [Table 4]

[0099] To 100 parts by mass of the obtained mixed powder, 2 to 3 parts by mass of an insulating binder consisting of acrylic resin and phenolic resin, and 0 to 0.5 parts by mass of a lubricant consisting of zinc stearate were mixed, and water was used as the solvent to obtain a slurry.

[0100] The obtained slurry was granulated using the spray dryer apparatus 200 shown in Figure 2 under the conditions described above to obtain granulated powder.

[0101] (3) Compression molding The obtained granulated powder was filled into a mold and pressure-molded at a surface pressure of 980 MPa to obtain a molded body having a ring shape with an outer diameter of 20 mm, an inner diameter of 12 mm, and a thickness of 3 mm.

[0102] (4) Heat treatment The obtained molded body was placed in a furnace under a nitrogen atmosphere, and the furnace temperature was heated from room temperature (23°C) at a heating rate of 10°C / min to the annealing temperatures shown in Tables 1 to 4. This temperature was maintained for 1 hour, and then the body was cooled back to room temperature in the furnace to obtain a toroidal core made of compacted powder core 1.

[0103] (Test Example 1) Measurement of relative initial permeability μ The toroidal coils obtained by winding coated copper wire 20 times around the toroidal core fabricated in the examples were measured using an impedance analyzer (HP 4192A) at 1 MHz to determine the relative initial permeability μ. The measurement results are shown in Tables 1 to 4.

[0104] (Test Example 2) Measurement of Iron Loss Pcv For the toroidal coils obtained by winding coated copper wire 15 times on the primary side and 10 times on the secondary side of the toroidal core fabricated in the examples, the iron loss Pcv (unit: kW / m) was measured using a BH analyzer (Iwasaki Communication Equipment Co., Ltd. "SY-8217") at a measurement frequency of 1 MHz, under the condition that the effective maximum magnetic flux density Bm was 15 mT. 3 The following measurements were taken. The measurement results are shown in Tables 1 to 4.

[0105] (Test Example 3) DC superimposed rated current Isat An inductance element was fabricated by winding copper wire around a toroidal core created in the example. For this inductance element, the DC superimposed rated current Isat (in mA) was determined as the current value at which the self-inductance L decreases by 30% when DC current is superimposed. Here, Isat was calculated by winding 34 turns of wire onto a toroidal core with an outer diameter of 20 mm, an inner diameter of 12.7 mm, and a height of 3.1 mm, and then passing current through it. The measurement results are shown in Tables 1 to 5.

[0106] (Evaluation example 1) μ 2 ×Isat / Pcv Based on the results measured in Test Examples 1 to 3, the overall characteristic is μ 2 ×Isat / Pcv (Unit: mA·kW) -1 m 3 The following was calculated. The calculation results are shown in Tables 1 and 5.

[0107] As shown in Tables 1 to 3, the median diameter D50c of crystalline particles is 1.3 μm or less, the median diameter D50a of amorphous particles is 2.0 μm or more and 12.0 μm or less, and the median diameter D50 of soft magnetic metal powder is 1.8 μm or more and 7.0 μm or less, resulting in the overall properties (μ 2 It was confirmed that the ×Isat / Pcv ratio was favorable. In particular, the iron loss Pcv was 70kW. -1 m 3 The following is true: Overall characteristics (μ 2 ×Isat / Pcv) is 400mA·kW -1 m 3This is easily achievable, and the overall characteristic is 400mA·kW -1 m 3 From the perspective of achieving this more stably, the iron loss Pcv is 60kW -1 m 3 The following is preferable: 55kW -1 m 3 It was confirmed that the following is more preferable.

[0108] Comparing the results shown in Tables 1 to 3 regarding the relationship between annealing temperature and overall characteristics, it can be seen that when the crystalline particles have an Fe-Ni alloy, the overall characteristics tend to improve as the annealing temperature decreases, but when the crystalline particles have an Fe-Si-Cr alloy, the overall characteristics tend to decrease as the annealing temperature decreases. It should be noted that even when the crystalline particles have an Fe-Si-Cr alloy, inductors with excellent overall characteristics were sometimes obtained. Specifically, Example 22 falls into this category and is shown as a reference example in Table 3. However, when the crystalline particles have an Fe-Si-Cr alloy, the range of median diameter D50c for crystalline particles that yield good overall characteristics was limited. Therefore, it can be said that when the crystalline particles have an Fe-Ni alloy, the range of median diameter D50c for crystalline particles that yield good overall characteristics is wider than when the crystalline particles have an Fe-Si-Cr alloy, and thus it is superior from the standpoint of design flexibility and ease of quality control.

[0109] Figure 7 is a graph of the results shown in Examples 26 to 29, and Figure 8 is a graph of the results shown in Examples 30 to 33. As can be seen from these graphs, even within the scope of the inventive examples, by optimizing the median diameter D50 of the magnetic powder, the overall characteristics (μ 2 It is possible to further increase the ×Isat / Pcv. Specifically, the median diameter D50 of the magnetic powder is more preferably 3 μm or more and 5.5 μm or less, and particularly preferably 3.5 μm or more and 5 μm or less.

[0110] (Evaluation Example 2) Average circular equivalent diameter of particles For the compacted core according to Example 5-3, a secondary electron image was obtained by imaging the cross-section with a scanning electron microscope (Figure 9). As shown in Figure 9, 32 amorphous particles located within the field of view of the secondary electron image were arbitrarily selected, and the equivalent circle diameter was determined for each. Figure 9 shows the numbers of the amorphous particles selected for measurement. In addition, 40 crystalline particles located between the amorphous particles were arbitrarily selected, and the equivalent circle diameter was also determined for each. The method for determining the equivalent circle diameter was as follows: First, for the selected particles, the lateral length L1 (unit: μm) and vertical length L2 (unit: μm) of the particle in the image were measured. Based on these measurement results, an approximate value of the particle's cross-sectional area was obtained by L1 × L2 × π / 4, and the equivalent circle diameter was determined from this approximate value. The measurement and calculation results are shown in Table 5. Table 5 also shows the average value, maximum value, and minimum value for amorphous particles and crystalline particles, as well as the median diameter based on particle size distribution measurement by laser diffraction and scattering method.

[0111] [Table 5]

[0112] As shown in Table 5, for amorphous particles, the median diameter D50a was 5.5 μm, while the average equivalent particle size was 3.47 μm, which is 63% of the median diameter D50a. For crystalline particles, the median diameter D50a was 0.9 μm, while the average equivalent particle size was 0.57 μm, which is 63% of the median diameter D50c. Thus, the equivalent diameter was calculated to be 63% of the median diameter. [Industrial applicability]

[0113] The inductor equipped with the powdered core of the present invention can be suitably used as an inductor that is a component of a switching power supply circuit such as a DC-DC converter. [Explanation of symbols]

[0114] 1…Flour-compacted core (toroidal core) 10... Toroidal coil 2...Insulated conductive wire 2a... Coil 2b, 2c... Ends of insulated conductive wire 2 2d, 2e... Ends of coil 2a 20…Coil-embedded inductor 21...Flour core 22...Insulated conductive wire 22a, 22b...ends 23a, 23b... Connection ends 22c... Coil section 200... Spray dryer device 201... Rotor S...Slurry P…Granulated powder

Claims

1. A compacted core containing soft magnetic metal powder, The soft magnetic metal powder comprises a plurality of crystalline particles and a plurality of amorphous particles. The median diameter D50c of the plurality of crystalline particles is 1.3 μm or less. The median diameter D50a of the plurality of amorphous particles is 2.0 μm or more and 12.0 μm or less. The crystalline particles have a composition containing Fe and Ni. The median diameter D50 of the soft magnetic metal powder is calculated from the following formula (1) and is characterized in that it is 1.8 μm or more and 7.0 μm or less. D50=(Rc×D50c+Ra×D50a) / 100 (1) Here, Rc is the mass ratio (unit: mass%) of the plurality of crystalline particles to the soft magnetic metal powder, and Ra is the mass ratio (unit: mass%) of the plurality of amorphous particles to the soft magnetic metal powder.

2. The compacted core according to claim 1, wherein the metallic portion of the amorphous particles consists of an amorphous phase.

3. The compacted core according to claim 1, wherein the median diameter D50a of the plurality of amorphous particles is 3.5 μm or more and 9.0 μm or less.

4. The compacted core according to claim 1, wherein the median diameter D50c of the plurality of crystalline particles is 0.50 μm or more and 1.3 μm or less.

5. The compacted core according to claim 1, wherein the mass ratio Ra of the plurality of amorphous particles to the soft magnetic metal powder is 10% by mass or more and 90% by mass or less.

6. The compacted core according to claim 5, wherein the mass ratio Ra of the plurality of amorphous particles to the soft magnetic metal powder is 35% by mass or more and 85% by mass or less.

7. The compacted core according to claim 1, wherein the plurality of crystalline particles have a composition comprising 10% by mass or more and 90% by mass or less of Ni, with the remainder being Fe and impurities.

8. The plurality of amorphous particles are, P: 5.0 to 13.0 atomic% C: 2.2 to 13.0 atomic% Ni: 0 to 10.0 atomic% B: 0 to 9.0 atomic% Si: 0 to 7.0 atomic% Cr: 0 to 6.0 atomic% Sn: 0-3.0 atomic percent The compacted core according to claim 1, comprising a metallic portion having a composition in which the remainder consists of Fe and impurities.

9. The compacted core according to claim 1, wherein the plurality of amorphous particles consist of a first particle in which the metallic portion is made up of an amorphous phase, and a second particle having a metallic portion in which the Scherrer diameter is 50 nm or less and the crystalline phase is made up of an amorphous phase.

10. The compacted core according to claim 9, wherein the mass ratio Ra2 of the second particle to the plurality of amorphous particles is 80% by mass or less.

11. The compacted core according to claim 10, wherein the mass ratio Ra2 of the second particle to the plurality of amorphous particles is 1% by mass or more and 60% by mass or less.

12. The compacted core according to claim 9 or claim 10, wherein the median diameter D50a1 of the first particle is 3.5 μm or more and 9.0 μm or less.

13. The compacted core according to claim 9 or claim 10, wherein the median diameter D50a2 of the second particle is 2.0 μm or more and 15 μm or less.

14. The median diameter D50a of the plurality of amorphous particles is calculated from the following formula (2) and is 3.0 μm or more and 8.0 μm or less, according to claim 9 or claim 10: D50a=(Ra1×D50a1+Ra2×D50a2) / 100 (2) Here, Ra1 is the mass ratio (unit: mass%) of the first particle to the plurality of amorphous particles, and Ra2 is the mass ratio (unit: mass%) of the second particle to the plurality of amorphous particles.

15. The compacted core according to claim 9 or claim 10, wherein the median diameter D50c of the plurality of crystalline particles is 0.5 μm or more and 1.3 μm or less.

16. The compacted core according to claim 9 or claim 10, wherein the mass ratio Ra of the plurality of amorphous particles to the soft magnetic metal powder is 10% by mass or more and 90% by mass or less.

17. The compacted core according to claim 16, wherein the mass ratio Ra of the plurality of amorphous particles to the soft magnetic metal powder is 35% by mass or more and 60% by mass or less.

18. The compacted core according to claim 9 or 10, wherein the plurality of crystalline particles have a metallic portion with a composition consisting of 10% by mass or more and 90% by mass or less of Ni, with the remainder being Fe and impurities.

19. The plurality of amorphous particles are, P: 5.0 to 13.0 atomic% C: 2.2 to 13.0 atomic% Ni: 0 to 10.0 atomic% B: 0 to 9.0 atomic% Si: 0 to 7.0 atomic% Cr: 0 to 6.0 atomic% Sn: 0-3.0 atomic percent The compacted core according to claim 9 or claim 10, comprising a metallic portion having a composition in which the remainder consists of Fe and impurities.

20. The second particle is, Element X consisting of one or more elements selected from the group consisting of C, B, P, and Si: 5 atomic percent or more and 20 atomic percent or less. Element M consisting of one or more elements selected from the group consisting of Mo, Nb, Cu, Zr, Al, and V: 1 atomic% to 10 atomic% A compacted powder core according to claim 9 or claim 10, having a composition containing the above, with the remainder being Fe and impurities.

21. The D50a of the plurality of amorphous particles is 3.5 μm or more and 9.0 μm or less. The D50c of the aforementioned plurality of crystalline particles is 0.50 μm or more and 1.3 μm or less. The mass ratio Ra of the plurality of amorphous particles to the soft magnetic metal powder is 35% by mass or more and 60% by mass or less. The plurality of amorphous particles are, P: 5.0 to 13.0 atomic% C: 2.2 to 13.0 atomic% Ni: 0 to 10.0 atomic% B: 0 to 9.0 atomic% Si: 0 to 7.0 atomic% Cr: 0 to 6.0 atomic% Sn: 0-3.0 atomic percent The compacted core according to claim 1, having a composition containing, with the remainder being Fe and impurities, and having a metallic portion consisting of an amorphous phase.

22. When measured under conditions of a frequency of 1 MHz and an effective maximum magnetic flux density Bm of 15 mT, the iron loss Pcv was 70 kW. -1 I understand 3 The powder compacted core according to claim 1, which is as follows:

23. A compacted core containing soft magnetic metal powder, The soft magnetic metal powder comprises a plurality of crystalline particles and a plurality of amorphous particles. When observing the cross-section of the compacted powder core, The average equivalent diameter of the plurality of crystalline particles is 1.0 μm or less. The average equivalent circular diameter of the plurality of amorphous particles is 1.0 μm or more and 8.0 μm or less. A compacted core characterized in that the ratio of the occupied cross-sectional area of ​​the plurality of amorphous particles in the observation field to the occupied cross-sectional area of ​​the soft magnetic metal powder in the observation field is 30% or more and 70% or less.

24. Connection terminals, A conductor electrically connected to the aforementioned connection terminal and capable of generating an induced magnetic field when energized, A compacted powder core according to any one of claims 1, 2, and 9, Equipped with, The compacted powder core is positioned so that the magnetic field lines of the induced magnetic field from the conductor pass through it. An inductor characterized by the following.

25. An electronic or electrical device having an inductor as described in claim 24 mounted, wherein the inductor is connected to a circuit board at the connection terminal.

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