TW201901709A - Dust core, method for producing said dust core, inductor provided with said dust core, and electronic/electrical device on which said inductor is mounted - Google Patents

Abstract

Provided is a dust core which is suitable as a constituent member for a small and low inductor with a built-in coil, and which contains a powder of a crystalline magnetic material and a powder of an amorphous magnetic material. This dust core is configured such that: a first mixing ratio, which is the mass ratio of the content of the powder of the crystalline magnetic material to the sum of the content of the powder of the crystalline magnetic material and the content of the powder of the amorphous magnetic material, is from 30% by mass to 70% by mass (inclusive); the crystalline magnetic material is composed of an Fe-Si-Cr system alloy; and the median diameter D50C thereof is from 2.5 [mu]m to 6 [mu]m (inclusive).

Description

Powder core, method for producing the powder core, inductor including the powder core, and electronic/electrical machine to which the inductor is attached

The present invention relates to a powder core, a method of manufacturing the powder core, an inductor including the powder core, and an electric / electric machine to which the inductor is mounted. In the present specification, the term "inductor" means a passive component including a core material and a coil including a powder core.

In electronic devices such as smart phones, tablet terminals, and notebook computers, the demand for miniaturization, weight reduction, and high performance has increased. In response to this requirement, the switching power supply circuit within the electronic machine must be able to handle higher frequencies. Therefore, the inductor assembled into the switching power supply circuit is required to be stably driven at a high frequency. In order to provide a constituent material of a magnetic element capable of coping with a high driving frequency, Patent Document 1 discloses a metal magnetic material powder including a first particle having an average first particle diameter and having an average second particle. The second particle of the diameter, and the ratio of the average first particle diameter to the average second particle diameter is 1/8 to 1/3, and the mixing ratio of the first particle to the second particle is 10/by volume. 90 to 25/75. [Prior Art Document] [Patent Document] [Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-192729

[Problems to be Solved by the Invention] In recent years, switching power supply circuits, particularly DC (direct current)-DC converters, have been particularly demanding for miniaturization, and as a result of responding to such requirements, inductors are assembled inside. Constantly small and circulated large DC current. Therefore, the magnetic environment in which the magnetic material constituting the inductor is placed is an environment in which a current fluctuation (switching current) based on a switch at a high frequency is applied in a state where an induced magnetic field due to the direct current is applied as a bias voltage. The magnetic field caused by the change. Therefore, it is required that the magnetic material constituting the inductor has appropriate magnetic properties (e.g., high relative magnetic permeability) in such a magnetically harsh environment. Moreover, the requirements for the thinning of electronic devices are also strong, and the components on the substrates in the machine are also strongly required to be lowered in height. When the inductor, particularly the coil-embedded inductor, is lowered in height, the absolute amount of the magnetic material located around the coil is reduced, so that it is difficult to maintain the insulating properties of the inductor and maintain the mechanical properties of the core. The present invention has been made in view of the above circumstances, and an object thereof is to provide a powder core suitable as a constituent member of a small-sized and low-height coil-incorporated inductor, and a powder core which can be used as an inductor material having the powder core, the powder A method of manufacturing a core, an inductor including the powder core, and an electric / electrical device to which the inductor is mounted. [Technical means for solving the problem] An aspect of the present invention provided to solve the above problems is a powder core characterized in that it contains a powder of a crystalline magnetic material and a powder of an amorphous magnetic material, and The first mixing ratio is 30% by mass or more and 70% by mass based on the mass ratio of the content of the powder of the crystalline magnetic material to the total of the content of the powder of the crystalline magnetic material and the content of the powder of the amorphous magnetic material. Hereinafter, the crystalline magnetic material contains an Fe—Si—Cr-based alloy, and the median diameter D ₅₀ C is 2.5 μm or more and 6 μm or less. As described above, the current flowing in the inductor fluctuates in a state in which DC is superimposed. Therefore, the magnetic material constituting the powder core is required to have a high magnetic permeability even in a state in which the external magnetic field is somewhat high. The magnetic permeability in the high magnetic field is a parameter that is heterogeneous with the initial magnetic permeability, and cannot be said to have a strong intermediate phase with the saturation magnetic flux density. As an example of the parameter for evaluating the magnetic permeability in such a high magnetic field, the relative magnetic permeability, that is, μ5500 when the external magnetic field is 5500 A/m is exemplified. The higher the μ5500, the more excellent the magnetic properties of the magnetic material in a high magnetic field. Further, when the inductor is small and has a low height, the volume of the core located around the built-in coil is small. As a problem that is feared in this case, insulation breakdown of the core and breakage (breakage or defect) of the core are exemplified. Therefore, it is preferable that the core insulation withstand voltage (unit: V/mm) and radial crushing strength (unit: MPa) are high. Therefore, by using a powder core having a μ5500×insistance withstand voltage×high radial crushing strength, an inductor having excellent magnetic properties even in a small magnetic field and a high magnetic field can be obtained. Therefore, the conditions for providing a powder core having a μ5500×insulation withstand voltage×high radial crushing strength have been studied, and as a result, the following knowledge has been obtained: a powder of a magnetic material contained in a powder core (magnetic powder) It satisfies the following matters, and even if it has a small and low-profile shape, it is less likely to cause insulation breakdown or breakage of the core, and the inductor using the core can have appropriate magnetic characteristics even when used in a high magnetic field. (Item 1) The magnetic powder is a mixture of a powder of a crystalline magnetic material and a powder of an amorphous magnetic material. (Item 2) The first mixing ratio is 30% by mass or more and 70% by mass or less. (Problem 3) The crystalline magnetic material contains an Fe—Si—Cr-based alloy, and the median diameter D ₅₀ C is 2.5 μm or more and 6 μm or less. By satisfying these matters, it is possible to obtain a powder core having a μ5500 × insulation withstand voltage × radial crushing strength which is particularly high. In the above-mentioned powder core, it is preferable that the powder of the amorphous magnetic material has a median diameter D ₅₀ A of 5 μm or more and 8 μm or less. When the case 2 is satisfied, the μ5500×insulation withstand strength×radial crushing strength can be specifically increased by the median diameter D ₅₀ A of 5 μm or more. From this viewpoint, it is more preferable that the median diameter D ₅₀ A is 5.5 μm or more. On the other hand, when the median diameter D ₅₀ A is excessively large, the μ5500×insulation withstand voltage×radial crushing strength is liable to be lowered, or iron loss, particularly at high frequency, is increased. Therefore, the median diameter D ₅₀ A is preferably 8 μm or less, more preferably 7 μm or less. In the powder core, it is preferable that the powder median diameter D ₅₀ A of the amorphous magnetic material and the powder median diameter D ₅₀ C of the crystalline magnetic material satisfy the following formula (1). By making the particle diameters of the two kinds of powders satisfy the relationship of the following formula (1), it is more stably achieved that the μ5500×insulation withstand voltage×radial crushing strength is improved. 1≦D ₅₀ A/D ₅₀ C≦3.5 (1) In the above-mentioned powder core, by setting the first mixing ratio to 40% by mass or more and 60% by mass or less, it is possible to specifically increase μ5500×insulation withstand voltage× Radial crush strength. In the above-mentioned powder core, it is preferable that the amorphous magnetic material may further comprise a material selected from the group consisting of Fe-Si-B alloy, Fe-PC alloy, and Co-Fe-Si-B alloy. One or two or more materials of the group, and the amorphous magnetic material contains an Fe-PC alloy. In the above-mentioned powder core, there is a case where it is easy to improve by containing a binder component in which the powder of the crystalline magnetic material and the powder of the amorphous magnetic material are adhered to other materials contained in the powder core. The insulation pressure of the powder core or the increase of the radial crush strength. In this case, the above-mentioned bonding component may also contain a component based on a resin material. Another aspect of the present invention provides a method of producing a powder core comprising the above-described binder component comprising a resin material-based component. The production method includes a molding step of obtaining a molded article by a molding process including press molding of a mixture, the mixture comprising a powder of the crystalline magnetic material and a powder of the amorphous magnetic material and a bond containing the resin material Ingredients. From the viewpoint of improving productivity, it is preferred that the molding treatment at this time is compression molding which is pressurized at a temperature of about 0.5 GPa to about 2 GPa in a temperature environment of about room temperature. According to still another aspect of the present invention, there is provided an inductor comprising: the powder core, a coil, and a connection terminal connected to respective ends of the coil, and at least a portion of the powder core is located via the connection terminal When the current flows through the coil, it is disposed in the induced magnetic field generated by the current. According to the excellent characteristics of the powder core, the inductor is not easily damaged or broken by insulation even if it is small in size and low in height, and is excellent in DC superposition characteristics. A further aspect of the present invention to provide a kind of electronic and electrical equipment, which is mounted based electronic and electric equipment of the inductor, the inductor and the connecting lines from the terminals connected to the substrate. The circuit in which the inductor is incorporated in the electronic / electrical device is not particularly limited. However, when it is used in a switching power supply circuit such as a DC-DC converter, it is easy to exhibit the advantages of the above-described inductor excellent in DC superposition characteristics. Moreover, when the electronic / electrical device is a portable device such as a smart phone, it is easy to provide an advantage that it is easy to cope with a small-sized and low-profile inductor. [Effects of the Invention] The powder core of the above invention is appropriately adjusted in the composition and particle size distribution of the powder of the crystalline magnetic material, and the mixing ratio of the powder of the crystalline magnetic material and the powder of the amorphous magnetic material (first Since the mixing ratio is the same, the inductor having the powder core can improve the DC superposition characteristics even in a small size and a low height. Moreover, according to the present invention, there is provided a method of manufacturing the above-described powder core, an inductor including the powder core, and an electric / electric machine to which the inductor is attached.

Hereinafter, embodiments of the present invention will be described in detail. 1. Powder core The powder core 1 of one embodiment of the present invention shown in Fig. 1 has an annular core shape and contains a powder of a crystalline magnetic material and a powder of an amorphous magnetic material. The powder core 1 of the present embodiment is manufactured by a production method including a molding process including press molding a mixture containing the powders. The powder core 1 of the present embodiment contains a powder in which a powder of a crystalline magnetic material and a powder of an amorphous magnetic material are adhered to other materials contained in the powder core 1 (the same type of material exists). In the case of the case, there are also bonding components for the case of different kinds of materials. (1) Powder of crystalline magnetic material The crystal magnetic material of the powder of the crystalline magnetic material contained in the dust core 1 of one embodiment of the present invention is crystalline (determined by usual X-ray diffraction) A diffraction spectrum having a clear peak at a specific level of material can be obtained and ferromagnetic, including an Fe-Si-Cr alloy. The Fe-Si-Cr alloy is a material having a relatively high saturation magnetic flux density, good soft magnetic properties, and high specific resistance among crystalline magnetic materials. Therefore, compared with other crystalline magnetic materials, for example, carbonyl iron powder, the loss is low even under conditions of high magnetic field and high frequency, and it is easy to exhibit good magnetic properties. Therefore, by making the powder of the crystalline magnetic material contained in the powder core 1 contain the Fe—Si—Cr-based alloy, even if the content of the powder of the crystalline magnetic material is increased relative to the crystalline magnetic material in the powder core 1 The mass ratio of the content of the powder to the sum of the contents of the powder of the amorphous magnetic material (also referred to as "the first mixing ratio" in the present specification), and the relative magnetic permeability in a high magnetic field environment, specifically, μ5500 Not easy to reduce. The content of Si and the content of Cr in the Fe-Si-Cr alloy are not limited. By way of example, the content of Si is about 2 to 7% by mass, the content of Cr is about 2 to 7% by mass, and the rest is Fe and unavoidable impurities. The shape of the powder of the crystalline magnetic material contained in the dust core 1 according to the embodiment of the present invention is not limited. The shape of the powder may be spherical or non-spherical. In the case of an aspherical shape, it may have a shape having an anisotropic shape such as a scaly shape, an elliptical shape, a droplet shape, or a needle shape. The shape of the powder may be a shape obtained at the stage of producing the powder, or may be a shape obtained by secondary processing of the produced powder. The shape of the former is exemplified by a spherical shape, an elliptical shape, a droplet shape, a needle shape, or the like, and the shape of the latter is exemplified by a scaly shape. The particle diameter of the powder of the crystalline magnetic material contained in the dust core 1 according to the embodiment of the present invention is such that the cumulative particle diameter distribution from the small particle diameter side in the volume-based particle size distribution becomes 50% ( Also referred to as "crystallized powder median diameter" in the present specification, D ₅₀ C is 2.5 μm or more and 6 μm or less. When the crystal powder median diameter D ₅₀ C is in the above range, when the first mixing ratio is 30% by mass or more and 70% by mass or less, the μ5500×insulation withstand voltage×radial crushing strength can be specifically increased. . There is a case where the crystal powder median diameter D ₅₀ C is preferably 2.5 μm or more and 5.5 μm or less, in consideration of the influence of the high frequency, particularly the iron loss Pcv of 1 MHz or more. At least a portion of the powder of the crystalline magnetic material may also be subjected to surface insulation treatment. When the surface of the crystalline magnetic material was subjected to surface insulation treatment, the tendency of the insulation resistance of the powder core 1 to be improved was observed. The type of surface insulation treatment performed on the powder of the crystalline magnetic material is not limited. Phosphoric acid treatment, phosphate treatment, oxidation treatment, and the like are exemplified. (2) Powder of amorphous magnetic material The amorphous magnetic material which provides the powder of the amorphous magnetic material contained in the powder core 1 of one embodiment of the present invention is amorphous (by the usual X) The ray diffraction measurement does not provide a diffraction spectrum having a clear peak to the extent that the material type can be specified, and is a ferromagnetic material, particularly a soft magnetic material, and the specific type is not limited. Specific examples of the amorphous magnetic material include an Fe-Si-B based alloy, an Fe-PC based alloy, and a Co-Fe-Si-B based alloy. The amorphous magnetic material may be composed of one material or a plurality of materials. The magnetic material constituting the powder of the amorphous magnetic material is preferably one or more selected from the group consisting of the above materials, and among these, it is preferable to contain an Fe-PC alloy, preferably It is an alloy containing Fe-PC. Specific examples of the Fe-PC-based alloy include Fe-based amorphous alloys having a composition formula of Fe _{100 atom % - a - b - c - x - y - z - t} Ni _a Sn _b Cr _c P _x C _y B _z Si _t represents, and 0 atom% ≦ a ≦ 10 atom%, 0 atom% ≦ b ≦ 3 atom%, 0 atom% ≦ c ≦ 6 atom%, 6.8 atom% ≦ x ≦ 13 atom%, 2.2 Atomic % ≦ y ≦ 13 Atomic %, 0 Atomic % ≦ z ≦ 9 Atomic %, 0 Atomic % ≦ t ≦ 7 Atomic %. In the above composition formula, Ni, Sn, Cr, B, and Si are arbitrary added elements. The addition amount a of Ni is preferably 0 atom% or more and 6 atom% or less, more preferably 0 atom% or more and 4 atom% or less. The addition amount b of Sn is preferably 0 atom% or more and 2 atom% or less, and may be added in a range of 1 atom% or more and 2 atom% or less. The amount c of Cr added is preferably 0 atom% or more and 2 atom% or less, more preferably 1 atom% or more and 2 atom% or less. There is also a case where the addition amount x of P is preferably 8.8 atom% or more. The addition amount y of C is preferably 5.8 atom% or more and 8.8 atom% or less. The amount z of addition of B is preferably 0 atom% or more and 3 atom% or less, more preferably 0 atom% or more and 2 atom% or less. The amount t of addition of Si is preferably 0 atom% or more and 6 atom% or less, more preferably 0 atom% or more and 2 atom% or less. The shape of the powder of the amorphous magnetic material contained in the powder core 1 according to the embodiment of the present invention is not limited. The type of the shape of the powder is the same as that of the powder of the crystalline magnetic material, and thus the description thereof is omitted. There is also a case where the amorphous magnetic material is easily formed into a spherical shape or an ellipsoidal shape in terms of the manufacturing method. Further, in general, since the amorphous magnetic material is harder than the crystalline magnetic material, it is preferable that the crystalline magnetic material is non-spherical and is easily deformed at the time of press molding. The shape of the powder of the amorphous magnetic material contained in the powder core 1 according to the embodiment of the present invention may be a shape obtained at the stage of producing the powder, or may be performed by secondary processing of the produced powder. Get the shape. The shape of the former is exemplified by a spherical shape, an elliptical shape, a needle shape, or the like, and the shape of the latter is exemplified by a scaly shape. The particle size of the powder of the amorphous magnetic material contained in the powder core 1 according to the embodiment of the present invention is 50% of the particle size distribution from the small particle size side in the volume-based particle size distribution. (also referred to as "amorphous powder median diameter" in the present specification) D ₅₀ A is preferably 5 μm or more and 8 μm or less. When the amorphous powder median diameter D ₅₀ A is 5 μm or more when the first mixing ratio is 30% by mass or more and 70% by mass or less, the μ5500×insulation withstand strength×radial crushing strength can be specifically increased. From this viewpoint, the amorphous powder median diameter D ₅₀ A is more preferably 5.5 μm or more. On the other hand, there is also a case where the amorphous powder has a median particle diameter D ₅₀ A which is excessively large, and has a μ5500×insulation withstand voltage×radial crushing strength reduction, or iron loss Pcv, especially in high frequency. The tendency of the iron loss Pcv to increase. Therefore, the amorphous powder median diameter D ₅₀ A is preferably 8 μm or less, more preferably 7 μm or less. Further, the particle diameter of the powder of the amorphous magnetic material contained in the powder core 1 according to the embodiment of the present invention may have the following relationship with the particle diameter of the powder of the amorphous magnetic material contained in the powder core 1. . That is, the amorphous powder median diameter D ₅₀ A and the crystalline powder median diameter D ₅₀ C may satisfy the following formula (1). 1≦D ₅₀ A/D ₅₀ C≦3.5 (1) By setting D ₅₀ A/D ₅₀ C in the range of 1 to 3.5, it is easy to specifically increase μ5500×insulation withstand voltage×radial pressure with respect to the powder core 1 Broken strength. From the viewpoint of more stably achieving a specific increase of μ5500 × insulation withstand voltage × radial crush strength, D ₅₀ A/D ₅₀ C preferably exists in the range of 1.2 to 2.5, and is preferably in the presence of The case of the range of 1.3 to 2.0. The first mixing ratio is preferably 40% by mass or more and 60% by mass or less, more preferably from the viewpoint that the powder core 1 is made to have a specific height of μ5500×insulation pressure×radial crushing strength. It is 40% by mass or more and 55% by mass or less. (3) Bonding Component The powder core 1 may contain a bonding component that bonds a powder of a crystalline magnetic material and a powder of an amorphous magnetic material to other materials contained in the powder core 1. The binder component is a powder which contributes to the powder of the crystalline magnetic material and the amorphous magnetic material contained in the powder core 1 of the present embodiment (in the present specification, the powder may be collectively referred to as "the powder". The material of the magnetic powder ") is not limited in its composition. Examples of the material constituting the binder component include an organic material such as a thermal decomposition residue of a resin material and a resin material (in the present specification, collectively referred to as "component based on a resin material"), and an inorganic material. Examples of the resin material include an acrylic resin, an anthrone resin, an epoxy resin, a phenol resin, a urea resin, and a melamine resin. A glass-based material such as water glass is exemplified as the binder component composed of an inorganic material. The bonding component may be composed of one material or a plurality of materials. The bonding component may also be a mixture of an organic material and an inorganic material. As the bonding component, an insulating material is usually used. Thereby, the insulation property of the powder core 1 can be improved. 2. Method for Producing Powder Core The method for producing the powder core 1 according to the embodiment of the present invention is not particularly limited. However, the production method described below is adopted to realize the production of the powder core 1 more efficiently. The method for producing the powder core 1 according to the embodiment of the present invention includes the molding step described below, and may further include a heat treatment step. (1) Forming Step First, a mixture containing a magnetic powder and a component which provides a binder component in the powder core 1 is prepared. The component that provides the bonding component (also referred to as "adhesive component" in the present specification) is either in the case of the bonding component itself or in the case of a material different from the bonding component. Specific examples of the latter include a case where the binder component is a resin material and the binder component is a thermally decomposed residue. Such a thermal decomposition residue is formed by a heat treatment step which is carried out after the forming step as described below. The shaped article can be obtained by a press forming process comprising the mixture. The pressurization conditions are not limited, and are appropriately set based on the composition of the binder component and the like. For example, in the case where the binder component includes a thermosetting resin, it is preferred to carry out pressurization and heating together to carry out a curing reaction of the resin in the mold. On the other hand, in the case of compression molding, although the pressing force is high, heating is not a necessary condition, and the pressing time is short. The pressing force in the case of compression molding is appropriately set. When it is not limited to an example, it is 0.5 GPa or more and 2 GPa or less, and preferably 1 GPa or more and 2 GPa or less. Hereinafter, the case where the mixture is a granulated powder and compression-molded will be described in some detail. Since the granulated powder is excellent in workability, workability in a compression molding step which is short in molding time and excellent in productivity can be improved. (1-1) Granulated powder The granulated powder contains a magnetic powder and a binder component. The content of the binder component in the granulated powder is not particularly limited. When the content is too low, the binder component does not easily retain the magnetic powder. Further, when the content of the binder component is too low, in the powder core 1 obtained by the heat treatment step, the binder component containing the thermal decomposition residue of the binder component is not easy to insulate the plurality of magnetic powders from each other with other magnetic powders. . On the other hand, when the content of the above-mentioned binder component is too high, the content of the binder component contained in the powder core 1 obtained by the heat treatment step tends to be high. When the content of the binder component in the powder core 1 becomes high, the magnetic properties of the powder core 1 are liable to lower. Therefore, the content of the binder component in the granulated powder is preferably 0.5% by mass or more and 5.0% by mass or less based on the total amount of the granulated powder. The content of the binder component in the granulated powder is preferably 1.0% by mass or more and 3.5% by mass based on the total amount of the granulated powder, from the viewpoint of more stably reducing the possibility that the magnetic properties of the powder core 1 are lowered. The amount below is more preferably 1.2% by mass or more and 3.0% by mass or less. The granulated powder may also contain materials other than the above magnetic powder and binder components. As such a material, a lubricant, a decane coupling agent, an insulating filler, or the like is exemplified. In the case of containing a lubricant, the kind thereof is not particularly limited. It can be an organic lubricant or an inorganic lubricant. Specific examples of the organic-based lubricant include metal soaps such as zinc stearate and aluminum stearate. It is considered that such an organic-based lubricant is vaporized in the heat treatment step and hardly remains in the powder core 1. The method for producing the granulated powder is not particularly limited. The granulated powder may be directly kneaded, and the obtained kneaded product may be pulverized by a known method to obtain a granulated powder, or a dispersing medium (for example, water may be mentioned) may be added to the above-mentioned components. The slurry is formed, and the slurry is dried and pulverized to obtain a granulated powder. It can also be sieved or classified after pulverization to control the particle size distribution of the granulated powder. An example of a method of obtaining a granulated powder from the above slurry is a method using a spray dryer. As shown in FIG. 2, a rotor 201 is provided in the spray dryer device 200, and the slurry S is injected toward the rotor 201 from the upper portion of the device. The rotor 201 is rotated at a specific number of revolutions, and the slurry S is sprayed in a droplet form by centrifugal force in a chamber inside the spray dryer device 200. Further, hot air is introduced into the chamber inside the spray dryer device 200, whereby the dispersion medium (water) contained in the droplet-shaped slurry S is volatilized in a state of maintaining a droplet shape. As a result, the granulated powder P is formed from the slurry S. This granulated powder P is recovered from the lower portion of the spray dryer unit 200. The number of revolutions of the rotor 201, the temperature of the hot air introduced into the spray dryer device 200, and the temperature of the lower portion of the chamber may be appropriately set. As a specific example of the setting range of the parameters, the number of revolutions of the rotor 201 may be 4,000 to 8,000 rpm, and the temperature of the hot air introduced into the spray dryer device 200 may be 100 to 170 ° C, and the temperature at the lower portion of the chamber may be 80 to 8%. 90 ° C. Moreover, the environment and pressure in the chamber can be set as appropriate. As an example, the chamber is an atmospheric (air) environment, and the pressure is 2 mmH ₂ O (about 0.02 kPa) at a pressure difference from atmospheric pressure. The particle size distribution of the obtained granulated powder P can also be controlled by sieving or the like. (1-2) Pressurization Conditions The pressurization conditions in compression molding are not particularly limited. It suffices to appropriately set the composition of the granulated powder, the shape of the molded article, and the like. When the pressing force at the time of compression molding of the granulated powder is too low, the mechanical strength of the molded article is lowered. Therefore, problems such as a decrease in workability of the molded article and a decrease in mechanical strength of the powder core 1 obtained from the molded article are likely to occur. Further, there is a case where the magnetic properties of the powder core 1 are lowered or the insulation properties are lowered. On the other hand, in the case where the pressing force at the time of compression molding of the granulated powder is too high, it is difficult to form a molding die capable of withstanding the pressure. The pressure applied to the compression molding of the granulated powder from the viewpoint of more stably reducing the possibility that the compression and pressurization step adversely affects the mechanical or magnetic properties of the powder core 1, and is industrially easy to mass-produce. It 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. In the compression molding, the pressure may be applied while heating, or may be performed at normal temperature. (2) Heat Treatment Step The molded article obtained by the forming step may be the powder core 1 of the present embodiment, and the powder core 1 may be obtained by subjecting the molded article to a heat treatment step as described below. In the heat treatment step, the molded article obtained by the above-described forming step is heated, thereby adjusting the magnetic properties by correcting the distance between the magnetic powders and imparting strain relief to the magnetic powder in the forming step. The magnetic properties are adjusted to obtain the powder core 1. The heat treatment step is as described above in order to adjust the magnetic properties of the powder core 1, and the heat treatment conditions such as the heat treatment temperature are set such that the magnetic properties of the powder core 1 are optimized. As an example of the method of setting the heat treatment conditions, the heating temperature of the molded article is changed, and other conditions such as the temperature increase rate and the holding time at the heating temperature are fixed. The evaluation criteria of the magnetic properties of the powder core 1 when the heat treatment conditions are set are not particularly limited. As a specific example of the evaluation item, the iron loss Pcv of the powder core 1 can be mentioned. In this case, the heating temperature of the molded article may be set so that the iron loss Pcv of the powder core 1 is the lowest. The measurement conditions of the iron loss Pcv are appropriately set, and examples thereof include a condition in which the frequency is 2 MHz and the effective maximum magnetic flux density Bm is 15 mT. The environment at the time of heat treatment is not particularly limited. In the case of an oxidizing environment, the possibility of excessive thermal decomposition of the binder component or the possibility of progress of oxidation of the magnetic powder is improved. Therefore, it is preferably carried out in an inert environment such as nitrogen or argon or a reducing atmosphere such as hydrogen. Heat treatment. In the case where the binder component is formed of a resin material, there is a case where the binder component becomes a thermal decomposition residue by the heat treatment as described above. It is considered that when the strain is relaxed as described above, the binder component becomes a thermal decomposition residue. 3. Inductor, Electronic/Electrical Apparatus An inductor according to an embodiment of the present invention includes the powder core 1, the coil, and a connection terminal connected to each end portion of the coil according to an embodiment of the present invention. Here, at least a part of the powder core 1 is disposed so as to be located in an induced magnetic field generated by the current when a current flows through the coil via the connection terminal. Since the inductor according to the embodiment of the present invention includes the powder core 1 according to the embodiment of the present invention, it has excellent DC superposition characteristics and is excellent in insulation properties and mechanical properties. An example of such an inductor is the toroidal coil 10 shown in FIG. The loop coil 10 includes a coil 2a formed by winding a covered conductive wire 2 around a ring-shaped powder core (ring core) 1. The end portions 2d and 2e of the coil 2a can be defined in a portion of the conductive line between the coil 2a composed of the wound coated conductive wire 2 and the end portions 2b and 2c covering the conductive wire 2. As described above, in the inductor of the present embodiment, the member constituting the coil and the member constituting the connection terminal may be formed of the same member. Another example of the inductor according to an embodiment of the present invention includes the coil-embedded inductor 20 shown in Fig. 4 . The coil-embedded inductor 20 can be formed in a small piece shape of several mm square, and has a powder core 21 having a box shape, and a coil portion 22c covering the conductive wire 22 is buried therein. The end portions 22a and 22b of the coated conductive wire 22 are located on the surface of the dust core 21 and exposed. A portion of the surface of the powder core 21 is covered by electrically connecting the ends 23a, 23b independently of each other. The connection end portion 23a is electrically connected to the end portion 22a of the covered conductive wire 22, and the connection end portion 23b is electrically connected to the end portion 22b of the covered conductive wire 22. In the coil-embedded inductor 20 shown in FIG. 4, the end portion 22a of the covered conductive wire 22 is covered by the connection end portion 23a, and the end portion 22b of the covered conductive wire 22 is covered by the connection end portion 23b. The method of embedding the coil portion 22c of the conductive wire 22 in the powder core 21 is not limited. The member around which the coated conductive wire 22 is wound may be placed in a mold, and the mixture containing the magnetic powder (granulated powder) may be supplied into the mold to be press-formed. Alternatively, a plurality of members including a mixture of magnetic powders (granulated powder) may be prepared in advance, and the members may be combined, and the coated conductive wires 22 may be placed in the void portions formed at this time to obtain an assembly. The assembly is subjected to press forming. The material of the covered conductive wire 22 including the coil portion 22c is not limited. For example, a copper alloy can be cited. The coil portion 22c may also be an edge coil. The material of the connection end portions 23a and 23b is also not limited. There is a case where it is preferable to provide a metallized layer formed of a conductive paste such as a silver paste and a plating layer formed on the metallized layer from the viewpoint of excellent productivity. The material forming the plating layer is not limited. Examples of the metal element contained in the material include copper, aluminum, zinc, nickel, iron, tin, and the like. Electronic and electric equipment system of one embodiment of the present invention is mounted with one embodiment of the present invention, electronic and electric apparatuses form of inductors, inductor-based and which use a connection terminal connected to the substrate. An example of a circuit including the inductor is a switching power supply circuit such as a DC-DC converter. In response to various requirements such as miniaturization, weight reduction, and high functionality of electronic and electrical equipment, the switching power supply circuit has a tendency to increase the switching frequency and increase the amount of current flowing through the circuit. Therefore, the current flowing through the inductor which is a component of the circuit also tends to have a high fluctuation frequency and an increase in the average current amount. In this regard, as described above, the inductor including the powder core according to the embodiment of the present invention can be appropriately operated in a high magnetic field environment even if it is small and has a low height. Therefore, in the switching power supply circuit including the inductor, the decrease in efficiency is suppressed, and the above various requirements can be responded to without causing heat generation. In this way, the electronic / electrical device to which the inductor of one embodiment of the present invention is mounted can be reduced in size and weight, and can be realized with high functionality. The embodiments described above are described in order to facilitate the understanding of the present invention, and are not intended to limit the present invention. Therefore, it is intended that all of the elements of the embodiments disclosed herein are intended to include all modifications and equivalents. [Examples] Hereinafter, the present invention will be specifically described by way of Examples and the like, but the scope of the present invention is not limited to the Examples and the like. (Example 1) (1) The Fe-based amorphous alloy powder was produced in such a manner as to be composed of Fe _{71 atom %} Ni _{6 atom %} Cr _{2 atom %} P _{11 atom %} C _{8 atom %} B _{2 atom %} . A raw material was used to prepare a powder (amorphous powder) of an amorphous magnetic material by a water atomization method. The powder of the obtained amorphous magnetic material was classified, and the particle size distribution of the classified powder was measured by volume distribution using "Microtrac particle size distribution measuring apparatus MT3300EX" manufactured by Nikkiso Co., Ltd. The particle size distribution from the small particle size side in the volume-based particle size distribution was 50% (the amorphous powder median diameter) D ₅₀ A was 6.5 μm. Further, as the powder of the crystalline magnetic material, a powder containing Fe-Si-Cr-based alloy, specifically, a content of Si of 3.5% by mass, a content of Cr of 4.5% by mass, and the balance being Fe and inevitable are prepared. An alloy of impurities, and the crystalline powder had a median diameter D ₅₀ C of 4.0 μm. Therefore, in the powder of Example 1, D ₅₀ A/D ₅₀ C was 1.6. (2) Preparation of granulated powder The powder of the amorphous magnetic material and the powder of the crystalline magnetic material were mixed so as to have a first mixing ratio shown in Table 1, to obtain a magnetic powder. 97.2 parts by mass of the magnetic powder, 2 to 3 parts by mass of the insulating binder containing the acrylic resin and the phenol resin, and 0 to 0.5 parts by mass of the lubricant containing zinc stearate are mixed in water as a solvent to obtain a slurry. The obtained slurry was granulated under the above conditions using the spray dryer device 200 shown in Fig. 2 to obtain a granulated powder. (3) Compression molding The obtained granulated powder was filled in a mold, and subjected to press molding at a surface pressure of 1 GPa to obtain a molded body having a ring shape of an outer diameter of 20 mm × an inner diameter of 12 mm × a thickness of 3 mm. (4) Heat treatment The obtained shaped body is placed in a furnace in a nitrogen gas flow environment, and the furnace temperature is heated from room temperature (23 ° C) at a heating rate of 10 ° C / min to an optimum core heat treatment temperature of 200 to 400 ° C. The temperature was maintained at this temperature for 1 hour, and then heat-treated in a furnace to cool to room temperature to obtain a toroidal core including a powder core. [Table 1] (Example 2) Using the powder of the amorphous magnetic material produced in Example 1, the classification conditions were changed to prepare a powder of an amorphous magnetic material having an amorphous powder median diameter D ₅₀ A of 5.0 μm. Further, as the powder of the crystalline magnetic material, a powder containing Fe-Si-Cr-based alloy, specifically, a content of Si of 6.4% by mass, a content of Cr of 3.1% by mass, and the balance of Fe and inevitable impurities were prepared. The alloy was obtained, and the crystalline powder had a median diameter D ₅₀ C of 2.0 μm. Therefore, in the powder of Example 2, D ₅₀ A/D ₅₀ C was 2.5. The powder of the amorphous magnetic material and the powder of the crystalline magnetic material were mixed so as to have a first mixing ratio shown in Table 2 to obtain a magnetic powder. Hereinafter, a plurality of ring cores were obtained in the same manner as in Example 1. [Table 2] (Test Example 1) Measurement of Core Density ρ The dimensions and weights of the ring cores produced in Examples 1 and 2 were measured, and the density (core density) of each of the ring cores was calculated based on the values (unit: g /cc). The results are shown in Tables 1 and 2. (Test Example 2) Measurement of Initial Magnetic Permeability μ0 The ring-shaped cores produced in Examples 1 and 2 were obtained by winding a coated copper wire 10 times on the primary side and 10 times on the secondary side. The toroidal coil was measured for the initial magnetic permeability μ0 at 100 kHz using an impedance analyzer ("4192A" manufactured by HP Corporation). The results are shown in Tables 1 and 2. (Test Example 3) Measurement of μ5500 Using the toroidal coil produced in Test Example 2, a direct current was superimposed at 100 kHz, and the relative magnetic permeability μ5500 at which the induced magnetic field of the superimposed direct current was 5500 A/m was measured. The measurement results are shown in Table 1. (Test Example 4) Measurement of Radial Crush Strength The radial crush strength was determined by measuring the ring cores produced in Examples 1 and 2 according to the test method of JIS Z 2507:2000. The measurement results are shown in Tables 1 and 2. (Testing Example 5) Measurement of the dielectric breakdown voltage The dielectric breakdown voltage (unit: V) of the toroidal core produced in Example 1 and Example 2 (measurement equipment: "TOS5051" manufactured by Kikusui Electronics Co., Ltd.) was measured. The measurement was carried out in accordance with JIS C2110-1, and the both end faces of the annular core shown in Fig. 1 were sandwiched by a metal plate, and subjected to a 60-second step pressure test. The dielectric breakdown electric field (unit: V/mm) was obtained from the obtained insulation breakdown voltage. The results are shown in Tables 1 and 2. (Test Example 6) Measurement of Iron Loss Pcv The toroidal coil obtained by winding the coated copper wire on the primary side 15 times and the secondary side 10 times, respectively, in the ring cores produced in Example 1 and Example 2 Using a BH analyzer ("Yi-8217" manufactured by Iwasaki Communications Co., Ltd.), the iron loss Pcv (unit: kW/m ³ ) was measured at a measurement frequency of 2 MHz with an effective maximum magnetic flux density Bm of 15 mT. . The measurement results are shown in Tables 1 and 2. (Evaluation Example 1) μ5500 × insulation withstand voltage × radial crushing strength Based on the results measured by Test Example 3 to Test Example 5, μ5500 × insulation withstand voltage × radial crushing strength was calculated. The calculated results are shown in Tables 3 and 4 and FIG. Further, regarding the "relative value" in the above table and the drawings, in Example 1, the examples 1-2 to the examples were shown by the μ5500×insulation withstand strength×radial crushing strength in Example 1-1. The results of the standardization of values of 1-9 are shown in Example 2 to normalize the values of Examples 2-2 to 2-8 by the μ5500×insulation withstand strength×radial crush strength in Example 2-1. The result. [table 3] [Table 4] As shown in Table 3 and Table 4 and FIG. 5, in the first embodiment, as compared with the second embodiment, when the first mixing ratio is 30% by mass or more and 70% by mass or less, the relative value is specifically changed. high. It is understood that this tendency is remarkable particularly in the case of 40% by mass or more and 60% by mass or less. (Example 3) Using the powder of the amorphous magnetic material produced in Example 1, the classification conditions were changed, and the amorphous magnetic material having the amorphous powder median diameter D ₅₀ A as shown in Table 5 was prepared. Powder. Further, as the powder of the crystalline magnetic material, a powder having a value of the crystal powder of the Fe-Si-Cr alloy and having a median diameter D ₅₀ C as shown in Table 5 was prepared. The powder of the amorphous magnetic material and the powder of the crystalline magnetic material were mixed at a first mixing ratio of 50% by mass to obtain a magnetic powder. Hereinafter, a plurality of ring cores were obtained in the same manner as in Example 1. Regarding the obtained toroidal core, various measurements and evaluations were carried out in the same manner as in the case of Example 1. The results are shown in Table 5. [table 5] (Example 4) Using the powder of the amorphous magnetic material produced in Example 1, the classification conditions were changed, and a powder of an amorphous magnetic material having a median diameter D ₅₀ A of 5.0 μm was prepared. Further, as the powder of the crystalline magnetic material, a powder having a value of the value shown in Table 6 as the Fe-Si-Cr-based alloy and having a median diameter D ₅₀ C was prepared. The powder of the amorphous magnetic material and the powder of the crystalline magnetic material were mixed at a first mixing ratio of 30% by mass to obtain a magnetic powder. Hereinafter, a plurality of ring cores were obtained in the same manner as in Example 1. Regarding the obtained toroidal core, various measurements and evaluations were carried out in the same manner as in the case of Example 1. The results are shown in Table 6. [Table 6] As shown in Fig. 6 and Fig. 6 and the results of the measurement of the iron loss Pcv, the powder of the amorphous magnetic material and the powder of the crystalline magnetic material are confirmed to be present. When the value of the particle diameter increases, the iron loss Pcv tends to increase. Further, as shown in Figs. 8 and 9 and the measurement results of the relative values shown in Tables 5 and 9, it was confirmed that the powder of the amorphous magnetic material had a median diameter D ₅₀ A of 5 μm or more and 8 The powder median diameter D ₅₀ C of μm or less or the crystalline magnetic material is 2.5 μm or more and 6 μm or less, and the μ5500×insulation withstand voltage×radial crushing strength is specifically increased. (Example 5) Using the powder of the amorphous magnetic material produced in Example 1, the classification conditions were changed, and the median diameter D ₅₀ A was prepared to be 5.0 μm (Example 5-1) and 6.5 μm (Example 5) -2), and a powder of an amorphous magnetic material of 11.0 μm (Example 5-3). Further, as the powder of the crystalline magnetic material, a powder having a median diameter D ₅₀ C of 4.0 μm as an Fe—Si—Cr-based alloy was prepared. The powder of the amorphous magnetic material and the powder of the crystalline magnetic material were mixed at a first mixing ratio of 50% by mass to obtain a magnetic powder. Hereinafter, a plurality of ring cores were obtained in the same manner as in Example 1. Regarding the obtained toroidal core, various measurements and evaluations were carried out in the same manner as in the case of Example 1. The results are shown in Table 7 and Figure 10. [Table 7] (Example 6) Using the powder of the amorphous magnetic material produced in Example 1, the classification conditions were changed, and a powder of an amorphous magnetic material having a median diameter D ₅₀ A of 6.5 μm was prepared. Further, as a powder of a crystalline magnetic material, an Fe-Si-Cr alloy was prepared, and the median diameter D ₅₀ C was 2.0 μm (Example 5-1), 4.0 μm (Example 5-2), and 6.0. Powder of μm (Example 5-3). The powder of the amorphous magnetic material and the powder of the crystalline magnetic material were mixed at a first mixing ratio of 50% by mass to obtain a magnetic powder. Hereinafter, a plurality of ring cores were obtained in the same manner as in Example 1. Regarding the obtained toroidal core, various measurements and evaluations were carried out in the same manner as in the case of Example 1. The results are shown in Table 8 and Figure 11. [Table 8] Figure 12 shows the results of Example 5 and Example 6 normalized by the results of Example 5-2 (i.e., Example 6-2), and the horizontal axis represents the median diameter D ₅₀ A of the amorphous magnetic material. A graph of the ratio of the median diameter D ₅₀ C (D ₅₀ A/D ₅₀ C) of the powder of the crystalline magnetic material. As shown in Fig. 12, the dependence of μ5500×insulation withstand voltage×radial crushing strength with respect to D ₅₀ A/D ₅₀ C becomes a mountain type having a vertex at a range of 1.3 to 2.0 in D ₅₀ A/D ₅₀ C. The distribution of the trend line. [Industrial Applicability] The inductor including the powder core of the present invention can be preferably used as an inductor that is a component of a switching power supply circuit such as a DC-DC converter.

1‧‧‧Powder core (ring core)

2‧‧‧covered conductive wire

2a‧‧‧ coil

2b, 2c‧‧‧ covered end of conductive wire 2

2d, 2e‧‧‧ end of coil 2a

10‧‧‧Circular coil

20‧‧‧Coil-embedded inductors

21‧‧‧Powder core

22‧‧‧coated conductive wire

22a‧‧‧End

22b‧‧‧End

23a‧‧‧Connected end

23b‧‧‧Connecting end

22c‧‧‧ coil department

200‧‧‧ spray dryer unit

201‧‧‧Rotor

P‧‧‧Powder powder

S‧‧‧Slurry

Fig. 1 is a perspective view conceptually showing the shape of a powder core according to an embodiment of the present invention. Fig. 2 is a view conceptually showing a spray dryer device used in an example of a method for producing a granulated powder and an operation thereof. Fig. 3 is a perspective view conceptually showing the shape of a loop coil which is one type of inductor having a powder core according to an embodiment of the present invention. Fig. 4 is a perspective view conceptually showing the shape of a coil-embedded inductor including one of the inductors of the powder core according to the embodiment of the present invention. Fig. 5 is a graph showing the relationship between μ5500 × insulation withstand voltage × radial crush strength (relative value) and the first mixing ratio in Example 1 and Example 2. Fig. 6 is a graph showing the results of Example 3, and is a graph showing the relationship between the iron loss Pcv and the powder median diameter D ₅₀ A of the amorphous magnetic material. Fig. 7 is a graph showing the results of Example 4, and is a graph showing the relationship between the iron loss Pcv and the powder median diameter D ₅₀ C of the crystalline magnetic material. Figure 8 is a graph showing the results of Example 3, and shows the relationship between μ5500 × insulation withstand voltage × radial crush strength (relative value) and the powder median diameter D ₅₀ A of the amorphous magnetic material. Graph. Figure 9 is a graph showing the results of Example 4, and shows a relationship between μ5500 × insulation withstand voltage × radial crushing strength (relative value) and the powder median diameter D ₅₀ C of the crystalline magnetic material. Figure. Figure 10 is a graph showing the results of Example 5, and shows the relationship between μ5500 × insulation withstand voltage × radial crush strength (relative value) and the powder median diameter D ₅₀ A of the amorphous magnetic material. Graph. Figure 11 is a graph showing the results of Example 6, and is a graph showing the relationship between μ5500 × insulation withstand voltage × radial crush strength (relative value) and the powder median diameter D ₅₀ C of the crystalline magnetic material. Figure. Figure 12 is a result of normalizing the results of Example 5 and Example 6 by the results of Example 5-2 (i.e., Example 6-2), and comparing the median diameter D ₅₀ A of the amorphous magnetic material with respect to The ratio of the powder median diameter D ₅₀ C (D ₅₀ A/D ₅₀ C) of the crystalline magnetic material is a graph represented by the horizontal axis.

Claims (11)

A powder core characterized in that it contains a powder of a crystalline magnetic material and a powder of an amorphous magnetic material, and the content of the powder of the crystalline magnetic material is relative to the content of the powder of the crystalline magnetic material. The mass ratio of the total content of the powders of the amorphous magnetic material, that is, the first mixing ratio is 30% by mass or more and 70% by mass or less, and the crystalline magnetic material contains Fe-Si-Cr-based alloy and has a median diameter. D ₅₀ C is 2.5 μm or more and 6 μm or less. The powder core of claim 1, wherein the amorphous magnetic material has a powder median diameter D ₅₀ A of 5 μm or more and 8 μm or less. The powder core of claim 1 or 2, wherein the powder median diameter D ₅₀ A of the amorphous magnetic material and the powder median diameter D ₅₀ C of the crystalline magnetic material satisfy the following formula (1) ), 1≦D ₅₀ A/D ₅₀ C≦3.5 (1). The powder core of claim 1 or 2, wherein the first mixing ratio is 40% by mass or more and 60% by mass or less. The powder core of claim 1 or 2, wherein the amorphous magnetic material comprises a group selected from the group consisting of Fe-Si-B alloys, Fe-PC alloys, and Co-Fe-Si-B alloys. One or more materials. The powder core of claim 5, wherein the amorphous magnetic material comprises an Fe-P-C alloy. The powder core of claim 1 or 2, which contains a binder component which bonds the powder of the crystalline magnetic material and the powder of the amorphous magnetic material to other materials contained in the powder core. The powder core of claim 7, wherein the bonding component comprises a component based on a resin material. A method for producing a powder core, which is characterized by the method of producing the powder core of claim 8, and comprising a forming step of obtaining a shaped article by a press forming process comprising a mixture of a mixture, the mixture A powder comprising the crystalline magnetic material and a powder of the amorphous magnetic material and a binder component containing the resin material. An inductor comprising the powder core of any one of claims 1 to 8, a coil, and a connection terminal connected to each end of the coil, and at least a portion of the powder core is located above The connection terminal is disposed in such a manner that an electric field generated by the current is generated when the current flows through the coil. An electronic-electric machine, like mounting request entries based electronic and electric equipment of the inductors 10 and the inductor by the line connecting terminal is connected to the substrate.