JP2017208462A - Powder compact core, manufacturing method thereof, inductor with powder compact core, and electronic/electric device with inductor mounted thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a powder compact core including crystalline magnetic material powder and amorphous magnetic material powder, which is superior in dielectric voltage resistance and which can provide a satisfactory inductor reduced in iron loss.SOLUTION: A powder compact core comprises: crystalline magnetic material powder; and amorphous magnetic material powder. The first mixing ratio, which is a mass ratio of a content of the crystalline magnetic material powder to a total content of the crystalline magnetic material powder and the amorphous magnetic material powder, is 40-90 mass%.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a dust core, a method for manufacturing the dust core, an inductor including the dust core, and an electronic / electrical device on which the inductor is mounted. In this specification, the “inductor” is a passive element including a core material including a dust core and a coil, and includes the concept of a reactor.

  A dust core used in a booster circuit such as a hybrid vehicle, a reactor used in power generation or substation equipment, an inductor such as a transformer or a choke coil can be obtained by compacting soft magnetic powder. An inductor having such a dust core has low iron loss and excellent dielectric strength characteristics (in the present invention, a voltage that causes dielectric breakdown when a DC voltage or an AC voltage having a frequency of 60 Hz or less is applied to the inductor ( It means that the dielectric breakdown voltage) is high.

  Patent Document 1 discloses a mixed magnetic powder obtained by mixing iron-based crystalline alloy magnetic powder and iron-based amorphous alloy magnetic powder as a means for improving a decrease in insulation resistance in a high-temperature environment. A composite magnetic material is disclosed in which the blending ratio of the magnetic alloy magnetic powder and the amorphous alloy magnetic powder is 60 to 90 wt% and 40 to 10 wt%, respectively.

  In Patent Document 2, as a means for improving the insulation and corrosion resistance of a dust core, a mixed magnetic material powder obtained by mixing an amorphous magnetic alloy powder and a crystalline Fe—Cr alloy powder, and an insulating bond are disclosed. In the magnetic core material comprising the adhesive, the mixing ratio of the amorphous magnetic alloy powder and the Fe—Cr alloy powder is set to 10 to 60 wt% of the weight ratio of the Fe—Cr alloy powder to the mixed magnetic material powder. A composite magnetic material is disclosed.

JP 2004-197218 A JP 2007-134381 A

  Both Patent Document 1 and Patent Document 2 pay attention to the fact that the insulation resistance of the powder core decreases as the blending amount of the crystalline alloy powder increases, and the crystalline alloy magnetic powder and the amorphous alloy in the mixed magnetic powder By adjusting the blending ratio with the magnetic powder, the insulation resistance is prevented from decreasing. However, neither Patent Document 1 nor Patent Document 2 evaluates the dielectric strength characteristics of the dust core.

  Accordingly, the present invention provides a dust core containing a powder of a crystalline magnetic material and a powder of an amorphous magnetic material, which has excellent dielectric strength characteristics and provides a good inductor with reduced iron loss. The purpose is to provide a core. Another object of the present invention is to provide a method for manufacturing the above dust core, an inductor including the dust core, and an electronic / electrical device on which the inductor is mounted.

  As a result of investigations by the present inventors in order to solve the above-described problems, the crystalline magnetic material powder has a total content of the crystalline magnetic material powder content and the amorphous magnetic material powder content. By appropriately adjusting the first mixing ratio, which is the mass ratio of the content, it is possible to improve the dielectric strength characteristics of the dust core. In a preferred embodiment, the crystalline magnetic material contained in the dust core Exceeding the range estimated from the mixing ratio of the powder of the amorphous magnetic material and the powder of the amorphous magnetic material, to improve the dielectric strength characteristics of the dust core nonlinearly, and to provide a good inductor with reduced iron loss We obtained new knowledge that it becomes a powder core.

The invention completed by such knowledge is as follows.
One aspect of the present invention is a powder core containing a powder of a crystalline magnetic material and a powder of an amorphous magnetic material, the content of the powder of the crystalline magnetic material and the powder of the amorphous magnetic material The first mixing ratio, which is a mass ratio of the content of the powder of the crystalline magnetic material with respect to the total content, is a powder core of 40% by mass to 90% by mass.

  When the first mixing ratio satisfies the above relationship, the dielectric strength characteristics of the dust core exceed the range estimated from the powder of the crystalline magnetic material or the amorphous magnetic material in a non-linear manner. And a dust core that reduces the iron loss of the inductor.

  The powder core may have a first mixing ratio of 50% by mass to 70% by mass.

  The dust core may have a dielectric strength value of 120% or more with reference to the dielectric strength value of a dust core containing only the amorphous magnetic material powder as magnetic powder (100%).

  The dust core may have a dielectric strength value of 110% or more with reference to the dielectric strength value of the dust core containing only the crystalline magnetic material powder as the magnetic powder (100%).

  The crystalline magnetic material is Fe-Si-Cr alloy, Fe-Ni alloy, Fe-Co alloy, Fe-V alloy, Fe-Al alloy, Fe-Si alloy, Fe-Si-Al. One type or two or more types of materials selected from the group consisting of a system alloy, carbonyl iron and pure iron may be included.

  The crystalline magnetic material is preferably made of an Fe—Si—Cr alloy.

  The amorphous magnetic material includes one or more materials selected from the group consisting of Fe-Si-B alloys, Fe-PC-C alloys, and Co-Fe-Si-B alloys. You may go out.

  The amorphous magnetic material is preferably made of a Fe—PC alloy.

  The powder of the crystalline magnetic material is preferably made of an insulating material. By performing the insulation treatment, it is possible to more stably realize an improvement in the dielectric strength characteristics and insulation resistance of the dust core and a reduction in iron loss in the high frequency band.

  The dust core contains a binding component that binds the powder of the crystalline magnetic material and the powder of the amorphous magnetic material to another material contained in the dust core. Also good. In this case, the binding component preferably includes a component based on a resin material.

  Another aspect of the present invention is the above-described method for producing a dust core, wherein the addition of a mixture comprising the crystalline magnetic material powder, the amorphous magnetic material powder, and the binder component comprising the resin material is performed. A method for producing a powder core, comprising a molding step of obtaining a molded product by a molding process including pressure molding. By such a manufacturing method, it is possible to more efficiently manufacture the powder core.

  In the above manufacturing method, the molded product obtained by the molding step may be the powder core. Or you may provide the heat processing process which obtains the said powder core by the heat processing which heats the said molded product obtained by the said shaping | molding process.

  Still another aspect of the present invention is an inductor including the dust core, the coil, and a connection terminal connected to each end of the coil, wherein at least a part of the dust core is the connection. It is an inductor disposed so as to be located in an induced magnetic field generated by the current when a current is passed through the coil via a terminal. Such an inductor can achieve both excellent dielectric strength characteristics and low loss based on the excellent characteristics of the dust core.

  Still another embodiment of the present invention is an electronic / electrical device in which the inductor is mounted, and the inductor is an electronic / electrical device connected to a substrate by the connection terminal. Examples of such electronic / electrical equipment include a power supply device including a power supply switching circuit, a voltage raising / lowering circuit, and a smoothing circuit, and a small portable communication device. Since the electronic / electrical device according to the present invention includes the inductor, the electronic / electrical device can easily cope with higher voltages and higher frequencies.

  Since the 1st mixing ratio is adjusted appropriately for the dust core which concerns on said invention, it is possible to improve the dielectric strength characteristic of this dust core. Moreover, according to this invention, the manufacturing method of said powder core, the inductor provided with the said powder core, and the electronic / electrical device by which the said inductor was mounted are provided.

It is a perspective view which shows notionally the shape of the powder core which concerns on one Embodiment of this invention. It is a figure which shows notionally the spray dryer apparatus used in an example of the method of manufacturing granulated powder, and its operation | movement. It is a perspective view which shows notionally the shape of the toroidal coil which is 1 type of an inductor provided with the dust core which concerns on one Embodiment of this invention. It is a perspective view which shows notionally the shape of the coil embedding type | mold inductor which is a kind of inductor provided with the powder core which concerns on one Embodiment of this invention. 5 is a graph showing the dependency of the withstand voltage on the first mixing ratio in Example 1. It is the graph which showed the dependence with respect to the 1st mixing ratio of the withstand voltage in Example 2. It is the graph which showed the dependence with respect to the 1st mixing ratio of the withstand voltage in Example 1 and Example 2. FIG. It is the graph which showed the dielectric strength ratio in each 1st mixing ratio on the basis of the simple substance powder of an amorphous magnetic material in Example 1 and Example 2. FIG. It is the graph which showed the dielectric strength ratio in each 1st mixing ratio on the basis of the powder single-piece | unit of the crystalline magnetic material in Example 1 and Example 2. FIG. 6 is a graph showing the dependency of the insulation resistance on the first mixing ratio in Example 1. FIG. 4 is a graph showing the dependence of the core density on the first mixing ratio in Example 1. FIG. 4 is a graph showing the dependence of the magnetic permeability on the first mixing ratio in Example 1. It is the graph which showed the dependence with respect to the 1st mixing ratio of the insulation resistance in Example 2. FIG. 6 is a graph showing the dependence of the core density on the first mixing ratio in Example 2. 6 is a graph showing the dependence of the magnetic permeability on the first mixing ratio in Example 2.

Hereinafter, embodiments of the present invention will be described in detail.
1. A dust core 1 according to one embodiment of the present invention shown in FIG. 1 is a ring-shaped toroidal core, and contains a powder of a crystalline magnetic material and a powder of an amorphous magnetic material. . The powder core 1 according to the present embodiment is manufactured by a manufacturing method including a forming process including pressure forming a mixture containing these powders. As a non-limiting example, the dust core 1 according to the present embodiment includes a crystalline magnetic material powder and an amorphous magnetic material powder as other materials (same type of material) contained in the dust core 1. Or it may be a dissimilar material).

(1) Powder of crystalline magnetic material The crystalline magnetic material that gives the powder of crystalline magnetic material contained in the dust core 1 according to one embodiment of the present invention is crystalline (general X-ray diffraction) The specific type is not limited as long as a diffraction spectrum having a clear peak that can identify the material type is obtained by measurement) and that the material is a ferromagnetic material, particularly a soft magnetic material. Specific examples of crystalline magnetic materials include Fe-Si-Cr alloys, Fe-Ni alloys, Fe-Co alloys, Fe-V alloys, Fe-Al alloys, Fe-Si alloys, Fe-Si. -Al-based alloys, carbonyl iron and pure iron are mentioned. Said crystalline magnetic material may be comprised from one type of material, and may be comprised from multiple types of material. The crystalline magnetic material that gives the powder of the crystalline magnetic material is preferably one or more materials selected from the group consisting of the above materials, and among these, an Fe—Si—Cr alloy is used. It is preferable to contain, and it is more preferable to consist of a Fe-Si-Cr type alloy. Since the Fe—Si—Cr alloy is a material capable of relatively reducing the iron loss Pcv among the crystalline magnetic materials, the content of the crystalline magnetic material powder in the dust core 1 and the amorphous Even if the mass ratio of the content of the crystalline magnetic material powder to the total content of the magnetic material powder (also referred to as a “first mixing ratio” in this specification) is increased, the inductor provided with the dust core 1 Iron loss Pcv is difficult to increase. The Si content and the Cr content in the Fe—Si—Cr alloy are not limited. As an example which is not limited, it is mentioned that content of Si shall be about 2-7 mass%, and content of Cr shall be about 2-7 mass%.

  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 a non-spherical shape, it may have a shape anisotropy such as a scale shape, an oval sphere shape, a droplet shape, a needle shape, or an indefinite shape having no special shape anisotropy. Good. Examples of the amorphous powder include a case where a plurality of spherical powders are bonded in contact with each other, or are bonded so as to be partially embedded in other powders. Such amorphous powder is easily observed in carbonyl iron.

  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. Examples of the former shape include a spherical shape, an oval shape, a droplet shape, and a needle shape, and examples of the latter shape include a scale shape.

The particle size of the powder of the crystalline magnetic material contained in the powder core 1 according to the embodiment of the present invention is not limited. In the powder of the crystalline magnetic material, the particle size at which the cumulative particle size distribution from the small particle size side becomes 50% in the volume-based particle size distribution (also referred to as “median diameter” in this specification) D ₅₀ C is 15 μm or less. May be preferred. Since the crystalline magnetic material powder is softer than the amorphous magnetic material powder, there is a high possibility that the crystalline magnetic material powder is deformed inside the powder core 1. For this reason, the influence which the magnitude of a particle size has on the characteristic of the powder core 1 is relatively low. The median diameter D ₅₀ A of the crystalline magnetic material powder is preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 2 μm or less.

The content of the crystalline magnetic material powder in the dust core 1 is such that the first mixing ratio is 40% by mass or more and 90% by mass or less. When the first mixing ratio is 40% by mass or more and 90% by mass or less, the dielectric strength characteristics of the dust core 1 are improved as compared with the case where the first magnetic material is made of only an amorphous magnetic material. The improvement in the dielectric strength characteristics is considered to be because the dielectric breakdown energy is dispersed throughout the powder core 1 containing the crystalline magnetic material powder in the above range. From the viewpoint of stably improving the dielectric strength characteristics of the dust core 1, the first mixing ratio is more preferably 45% by mass to 85% by mass, and more preferably 50% by mass to 80% by mass. Particularly preferred. By setting the first mixing ratio within the above range, for example, a dust core 1 having good withstand voltage characteristics can be manufactured using an amorphous magnetic material having a D ₅₀ A of about 3 μm to 20 μm.

  The withstand voltage value of the dust core 1 is preferably 1.2 times or more, more preferably 1.25 times or more of the withstand voltage value of the dust core containing only the powder of the amorphous magnetic material as the magnetic powder. It is more preferable that the ratio is 1.3 times or more. Here, the “magnetic powder” refers to a crystalline magnetic material powder and an amorphous magnetic material powder contained in the dust core 1. “The dust core containing only the powder of the amorphous magnetic material as the magnetic powder” means the same components and conditions except that the crystalline magnetic material in the dust core is all replaced with an amorphous magnetic material. It refers to the powder core manufactured in

  At least a part of the powder of the crystalline magnetic material is preferably made of a material subjected to surface insulation treatment, and the powder of the crystalline magnetic material is more preferably made of a material subjected to surface insulation treatment. When the surface insulation treatment is performed on the powder of the crystalline magnetic material, the insulation resistance of the dust core 1 tends to be improved. The type of surface insulation treatment applied to the crystalline magnetic material powder is not limited. Examples include phosphoric acid treatment, phosphate treatment, and oxidation treatment.

(2) Amorphous Magnetic Material Powder The amorphous magnetic material that provides the amorphous magnetic material powder contained in the dust core 1 according to an embodiment of the present invention is amorphous (generally As long as the X-ray diffraction measurement does not provide a diffraction spectrum with a clear peak that can identify the material type), and the material is a ferromagnetic material, particularly a soft magnetic material, the specific types are limited. Not. Specific examples of the amorphous magnetic material include an Fe-Si-B alloy, an Fe-PC-C alloy, and a Co-Fe-Si-B alloy. Said amorphous magnetic material may be comprised from one type of material, and may be comprised from multiple types of material. The magnetic material constituting the powder of the amorphous magnetic material is preferably one or more materials selected from the group consisting of the above materials, and among these, an Fe—PC alloy is used. It is preferable to contain it, and it is more preferable that it consists of a Fe-PC-type alloy.

Specific examples of the Fe-P-C-based alloy, composition _formula, shown in _{Fe 100 atomic% -a-b-c-x} -y-z-t Ni a Sn b Cr c P x C y B z Si t 0 atom% ≦ a ≦ 10 atom%, 0 atom% ≦ b ≦ 3 atom%, 0 atom% ≦ c ≦ 6 atom%, 6.8 atom% ≦ x ≦ 13 atom%, 2.2 atom% ≦ Examples include Fe-based amorphous alloys in which y ≦ 13 atomic%, 0 atomic% ≦ z ≦ 9 atomic%, and 0 atomic% ≦ t ≦ 7 atomic%. In the above composition formula, Ni, Sn, Cr, B, and Si are optional added elements.

  The addition amount a of Ni is preferably 0 atom% or more and 6 atom% or less, and 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 the range of 1 atom% or more and 2 atom% or less. The addition amount c of Cr is preferably 0 atom% or more and 2 atom% or less, and more preferably 1 atom% or more and 2 atom% or less. In some cases, the addition amount x of P is preferably 8.8 atomic% or more. The addition amount y of C is preferably 4 atom% or more and 10 atom% or less, and may preferably be 5.8 atom% or more and 8.8 atom% or less. The addition amount z of B is preferably 0 atom% or more and 6 atom% or less, and more preferably 0 atom% or more and 2 atom% or less. The addition amount t of Si is preferably 0 atom% or more and 6 atom% or less, and more preferably 0 atom% or more and 2 atom% or less.

  The shape of the powder of the amorphous magnetic material contained in the dust core 1 according to the embodiment of the present invention is not limited. Since the kind of the powder shape is the same as that of the crystalline magnetic material powder, the description thereof is omitted. In some cases, the amorphous magnetic material can be easily formed into a spherical shape or an elliptical spherical shape because of the manufacturing method. In general, since an amorphous magnetic material is harder than a crystalline magnetic material, it may be preferable to make the crystalline magnetic material non-spherical so that it is easily deformed during pressure molding.

  The shape of the powder of the amorphous magnetic material contained in the dust core 1 according to the embodiment of the present invention may be the shape obtained in the stage of producing the powder, or the produced powder is secondary The shape obtained by processing may be sufficient. Examples of the former shape include a sphere, an oval sphere, and a needle shape, and examples of the latter shape include a scale shape.

As for 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, the median diameter D ₅₀ A of the powder of the amorphous magnetic material is preferably 50 μm or less. is there. When the median diameter D ₅₀ A of the powder of the amorphous magnetic material is 50 μm or less, it may be easy to reduce the iron loss Pcv while improving the insulation resistance of the powder core 1. From the viewpoint of more stably realizing the reduction of the iron loss Pcv while improving the insulation resistance of the dust core 1, the median diameter D ₅₀ A of the powder of the amorphous magnetic material is preferably 20 μm or less. In some cases, it is preferably 10 μm or less, more preferably 7 μm or less, and particularly preferably 5 μm or less.

(3) Binder Component The powder core 1 includes a binder component that binds the powder of the crystalline magnetic material and the powder of the amorphous magnetic material to the other materials contained in the powder core 1. It may be. The binder component is a powder of crystalline magnetic material and powder of amorphous magnetic material contained in the dust core 1 according to the present embodiment (in this specification, these powders are collectively referred to as “magnetic powder”). The composition is not limited as long as the material contributes to fixing. As a material constituting the binder component, an organic material such as a resin material and a thermal decomposition residue of the resin material (in this specification, these are collectively referred to as “components based on a resin material”), an inorganic material, and the like Is exemplified. Examples of the resin material include acrylic resin, silicone resin, epoxy resin, phenol resin, urea resin, and melamine resin. The binder component made of an inorganic material is exemplified by a glass-based material such as water glass. The binder component may be composed of one type of material or may be composed of a plurality of materials. The binder component may be a mixture of an organic material and an inorganic material.

  As the binding component, an insulating material is usually used. Thereby, it becomes possible to improve the insulation as the dust core 1.

2. Manufacturing method of powder core Although the manufacturing method of the powder core 1 which concerns on one embodiment of said this invention is not specifically limited, if the manufacturing method demonstrated below is employ | adopted, the powder core 1 will be manufactured more efficiently. Is realized.

  The manufacturing method of the powder core 1 which concerns on one Embodiment of this invention is equipped with the shaping | molding process demonstrated below, and may be further provided with the heat processing process.

(1) Molding step First, a mixture containing magnetic powder and a component that provides a binding component in the powder core 1 is prepared. The component that gives the binding component (also referred to as “binder component” in this specification) may be the binding component itself or may be a material different from the binding component. Specific examples of the latter include a case where the binder component is a resin material and the binder component is a thermal decomposition residue thereof.

  A molded product can be obtained by a molding process including pressure molding of the mixture. The pressurizing condition is not limited and is appropriately determined based on the composition of the binder component. For example, when the binder component is made of a thermosetting resin, it is preferable to heat the resin together with pressure to advance the resin curing reaction 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 pressurization is performed for a short time.

  Hereinafter, the case where the mixture is granulated powder and compression molding will be described in some detail. Since the granulated powder is excellent in handleability, it is possible to improve the workability of the compression molding process in which the molding time is short and the productivity is excellent.

(1-1) Granulated powder Granulated powder contains magnetic powder and a binder component. The content of the binder component in the granulated powder is not particularly limited. When this content is too low, it becomes difficult for the binder component to hold the magnetic powder. In addition, when the content of the binder component is excessively low, in the powder core 1 obtained through the heat treatment step, the binder component composed of the thermal decomposition residue of the binder component causes a plurality of magnetic powders to be separated from each other. It becomes difficult to insulate. On the other hand, when the content of the binder component is excessively high, the content of the binder component contained in the powder core 1 obtained through the heat treatment step tends to be high. When the content of the binder component in the dust core 1 is increased, the magnetic properties of the dust core 1 are likely to be reduced. Therefore, the content of the binder component in the granulated powder is preferably set to an amount that is 0.5% by mass or more and 5.0% by mass or less with respect to the entire granulated powder. From the viewpoint of more stably reducing the possibility that the magnetic properties of the dust core 1 will decrease, the content of the binder component in the granulated powder is 1.0 mass% or more with respect to the entire granulated powder. The amount is preferably 5% by mass or less, and more preferably 1.2% by mass or more and 3.0% by mass or less.

  The granulated powder may contain materials other than the above magnetic powder and binder component. Examples of such materials include lubricants, silane coupling agents, and insulating fillers. In the case of containing a lubricant, the type is not particularly limited. It may be an organic lubricant or an inorganic lubricant. Specific examples of the organic lubricant include metal soaps such as zinc stearate and aluminum stearate. It is considered that such an organic lubricant is vaporized in the heat treatment step and hardly remains in the powder core 1.

  The manufacturing method of granulated powder is not specifically limited. The ingredients that give the granulated powder may be kneaded as they are, and the resulting kneaded product may be pulverized by a known method to obtain granulated powder, or a dispersion medium (water as an example) It is also possible to obtain a granulated powder by preparing a slurry to which is added, and drying and pulverizing the slurry. Screening and classification may be performed after pulverization to control the particle size distribution of the granulated powder.

As an example of a method for obtaining granulated powder from the above slurry, a method using a spray dryer can be mentioned. As shown in FIG. 2, a rotator 201 is provided in the spray dryer apparatus 200, and the slurry S is injected toward the rotor 201 from the upper part of the spray dryer apparatus 200. The rotor 201 rotates at a predetermined number of revolutions, and sprays the slurry S as droplets by centrifugal force in a chamber inside the spray dryer apparatus 200. Further, hot air is introduced into the chamber inside the spray dryer apparatus 200, whereby the dispersion medium (water) contained in the droplet-like slurry S is volatilized while maintaining the droplet shape. As a result, the granulated powder P is formed from the slurry S. The granulated powder P is collected from the lower part of the spray dryer apparatus 200. Each parameter such as the number of rotations of the rotor 201, the temperature of hot air introduced into the spray dryer apparatus 200, and the temperature at the bottom of the chamber may be set as appropriate. As specific examples of the setting ranges of these parameters, the rotation speed of the rotor 201 is 4000 to 8000 rpm, the hot air temperature introduced into the spray dryer apparatus 200 is 130 to 170 ° C., and the temperature at the bottom of the chamber is 80 to 90 ° C. . The atmosphere in the chamber and its pressure may be set as appropriate. As an example, the inside of the chamber is an air atmosphere, and the pressure is ₂ mmH ₂ O (about 0.02 kPa) as a differential pressure from the atmospheric pressure. You may further control the particle size distribution of the obtained granulated powder P by sieving.

(1-2) Pressing conditions The pressing conditions in compression molding are not particularly limited. What is necessary is just to set suitably considering the composition of granulated powder, the shape of a molded article, etc. If the pressure applied when the granulated powder is compression-molded is excessively low, the mechanical strength of the molded product decreases. For this reason, it becomes easy to produce the problem that the handleability of a molded article falls and the mechanical strength of the compacting core 1 obtained from the molded article falls. Moreover, the magnetic characteristics of the dust core 1 may deteriorate or the insulating properties may decrease. On the other hand, when the pressing force when the granulated powder is compression-molded is excessively high, it becomes difficult to produce a molding die that can withstand the pressure. From the viewpoint of more stably reducing the possibility that the compression and pressurization process will adversely affect the mechanical properties and magnetic properties of the dust core 1 and facilitating mass production industrially, The applied pressure is preferably 0.3 GPa to 2 GPa, more preferably 0.5 GPa to 2 GPa, and particularly preferably 0.8 GPa to 2 GPa.

  In compression molding, pressurization may be performed while heating, or pressurization may be performed at room temperature.

(2) Heat treatment step The molded product obtained in the molding step may be the powder core 1 according to the present embodiment, or the molded product may be subjected to a heat treatment step and pressed as described below. A powder core 1 may be obtained.

  In the heat treatment process, the molded product obtained by the above molding process is heated to adjust the magnetic properties by correcting the distance between the magnetic powders and to relax the strain applied to the magnetic powder in the molding process. The powder core 1 is obtained by adjusting the magnetic characteristics.

  Since the purpose of the heat treatment step is to adjust the magnetic properties of the dust core 1 as described above, the heat treatment conditions such as the heat treatment temperature are set so that the magnetic properties of the dust core 1 are the best. As an example of a method for setting the heat treatment conditions, it is possible to change the heating temperature of the molded product and to make other conditions constant, such as the heating rate and the holding time at the heating temperature.

  The evaluation criteria for the magnetic properties of the dust core 1 when setting the heat treatment conditions are not particularly limited. The iron loss Pcv of the powder core 1 can be given as a specific example of the evaluation item. In this case, what is necessary is just to set the heating temperature of a molded product so that the iron loss Pcv of the powder core 1 may become the minimum. The measurement conditions of the iron loss Pcv are set as appropriate. As an example, the conditions are a frequency of 100 kHz and an effective maximum magnetic flux density Bm of 100 mT.

  The atmosphere during the heat treatment is not particularly limited. In the case of an oxidizing atmosphere, the possibility of excessive thermal decomposition of the binder component and the possibility of progress of oxidation of the magnetic powder increases, so that an inert atmosphere such as nitrogen or argon, or a reducing property such as hydrogen Heat treatment is preferably performed in an atmosphere.

3. Inductor, Electronic / Electric Device An inductor according to an embodiment of the present invention includes the dust core 1 according to the embodiment of the present invention, a coil, and a connection terminal connected to each end of the coil. Here, at least a part of the dust core 1 is disposed so as to be located in an induced magnetic field generated by the current when a current is passed through the coil via the connection terminal. Since the inductor according to an embodiment of the present invention includes the dust core 1 according to the above-described embodiment of the present invention, it has excellent withstand voltage characteristics and hardly increases iron loss even at high frequencies. Therefore, it is possible to reduce the size as compared with the inductor according to the prior art.

  An example of such an inductor is the toroidal coil 10 shown in FIG. The toroidal coil 10 includes a coil 2 a formed by winding a coated conductive wire 2 around a ring-shaped dust 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 formed of the wound covered conductive wire 2 and the ends 2b and 2c of the covered conductive wire 2. Thus, in the inductor according to the present embodiment, the member constituting the coil and the member constituting the connection terminal may be composed of the same member.

  As another example of the inductor according to the embodiment of the present invention, a coil embedded type inductor 20 shown in FIG. 4 can be cited. The coil-embedded inductor 20 can be formed in a small chip shape of several mm square, and includes a dust core 21 having a box shape, and a coil portion 22c in the covered conductive wire 22 is provided therein. Buried. End portions 22a and 22b of the coated conductive wire 22 are located on the surface of the powder core 21 and exposed. Part of the surface of the dust core 21 is covered with connection end portions 23a and 23b that are electrically independent from each other. The connection end portion 23 a is electrically connected to the end portion 22 a of the covered conductive wire 22, and the connection end portion 23 b is electrically connected to the end portion 22 b 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 with the connection end portion 23a, and the end portion 22b of the covered conductive wire 22 is covered with the connection end portion 23b.

  The method for embedding the coil portion 22c of the coated conductive wire 22 in the dust core 21 is not limited. A member around which the coated conductive wire 22 is wound may be placed in a mold, and a mixture (granulated powder) containing magnetic powder may be supplied into the mold to perform pressure molding. Alternatively, a plurality of members prepared by preforming a mixture (granulated powder) containing magnetic powder in advance are prepared, and these members are combined, and the coated conductive wires 22 are arranged in the gaps defined at that time. A solid may be obtained and this assembly may be pressure molded. The material of the covered conductive wire 22 including the coil portion 22c is not limited. For example, a copper alloy can be used. The coil portion 22c may be an edgewise coil. The material of the connection end portions 23a and 23b is not limited. From the viewpoint of excellent productivity, it may be preferable to include a metallized layer formed from a conductive paste such as a silver paste and a plating layer formed on the metallized layer. The material for forming the plating layer is not limited. Examples of the metal element contained in the material include copper, aluminum, zinc, nickel, iron, and tin.

  An electronic / electrical device according to an embodiment of the present invention is an electronic / electrical device in which the inductor according to the above-described embodiment of the present invention is mounted, and is connected to a substrate at the connection terminal. is there. Since the electronic device according to an embodiment of the present invention has the inductor according to the embodiment of the present invention mounted thereon, a high voltage or a high frequency signal may be applied to the device. However, it is difficult to cause problems due to the reduced function and heat generation of the inductor, and the device can be easily downsized.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.
Example 1

(1) Preparation of Fe-based amorphous alloy powder Fe _balance Ni _{5-7 atomic%} Cr _{2-4 atomic%} P _{10-13 atomic%} C _{5-6 atomic%} B _{2-4 atomic%} The raw materials were weighed, and an amorphous magnetic material powder (amorphous powder) was prepared using a water atomization method. The particle size distribution of the obtained amorphous magnetic material powder was measured by volume distribution using “Microtrack particle size distribution measuring device MT3300EX” manufactured by Nikkiso Co., Ltd. In the volume-based particle size distribution, the particle size (median diameter) D ₅₀ A at which the cumulative particle size distribution from the small particle size side becomes 50% was 5 μm.
Further, as a powder of crystalline magnetic material, Fe-Si-Cr-based alloy, specifically, Si content is 6-7 mass%, Cr content is 3-4 mass%, and the balance is A powder comprising an alloy composed of Fe and inevitable impurities and having a median diameter D ₅₀ C of 2 μm was prepared.

(2) Production of Granulated Powder The above-mentioned amorphous magnetic material powder and crystalline magnetic material powder were mixed so as to have the first mixing ratio shown in Table 1 to obtain a magnetic powder. 97.2 parts by mass of magnetic powder, 2 to 3 parts by mass of an insulating binder made of acrylic resin or phenol resin, and 0 to 0.5 parts by mass of a lubricant made of zinc stearate are added to water as a solvent. A slurry was obtained by mixing.

  The obtained slurry was granulated under the conditions described above using a spray dryer apparatus 200 shown in FIG. 2 to obtain granulated powder.

(3) Compression molding The obtained granulated powder is filled in a mold and press-molded at a surface pressure of 0.5 to 1.5 GPa to form a ring shape having an outer diameter of 20 mm, an inner diameter of 12 mm and a thickness of 3 mm. Got the body.

(4) Heat treatment The obtained molded body was placed in a furnace in a nitrogen stream atmosphere, and the furnace temperature was an optimum core heat treatment temperature from room temperature (23 ° C.) to a heating rate of 10 ° C./min. The mixture was heated to 0 ° C., held at this temperature for 1 hour, and then heat-treated to cool to room temperature in a furnace to obtain a toroidal core composed of a dust core.

  Toroidal cores having different first mixing ratios shown in Table 1 below were prepared, and the core density, insulation resistance, withstand voltage, magnetic permeability, and iron loss Pcv were measured by the following measurement methods.

(Test Example 1) Measurement of dielectric strength voltage Using a pressure resistance measuring device “TOS5051A” manufactured by Kikusui as a measuring device, a toroidal core as a sample was sandwiched between parallel plate electrodes, and an applied voltage was applied at AC (50 Hz). The breakdown voltage was determined as the withstand voltage.
The withstand voltage values of Examples 1-2 to 1-8 measured as described above are the withstand voltages of the toroidal core of Example 1-1 containing only the powder of the amorphous magnetic material as the magnetic powder. The withstand voltage ratio (100% of amorphous) with respect to the value (100%) as the reference value, and the withstand voltage value of the toroidal core of Example 1-8 containing only the powder of the crystalline magnetic material as the magnetic powder The dielectric strength ratio (100% crystalline basis) was determined when the standard (100%) was used.

(Test Example 2) Measurement of Insulation Resistance A high resistance measuring instrument “4339B” (former Agilent (currently Keysight)) was used as a measuring apparatus, and the measurement was performed by a two-terminal method at an applied voltage of 20V.

(Test Example 3) Measurement of core density ρ The dimensions and weight of the toroidal core produced in Example 1 were measured, and the density ρ (unit: g / cc) of each toroidal core was calculated from these numerical values.

(Test Example 4) Measurement of Magnetic Permeability The toroidal coil obtained by winding the coated copper wire on the toroidal core produced in Example 1 40 times on the primary side and 10 times on the secondary side, respectively, was analyzed using an impedance analyzer (manufactured by HP, “ 4192A "), the initial permeability μ0 was measured under the condition of 100 kHz.

(Test Example 5) Measurement of Iron Loss Pcv For the toroidal coils obtained by winding the coated copper wire around the toroidal core produced in Example 1 15 times on the primary side and 10 times on the secondary side, BH analyzer (Iwasaki Tsushinki) The core loss Pcv (unit: kW / m ³ ) was measured at a measurement frequency of 2 MHz under the condition that the effective maximum magnetic flux density Bm was 15 mT.
Table 1 shows the results measured using the methods of Test Examples 1 to 5 described above.

  FIG. 5 is a graph showing the dependence of the withstand voltage on the first mixing ratio for Example 1. As shown in the graph of dielectric strength voltage in the figure, in Example 1, by mixing the powder of the crystalline magnetic material with the powder of the amorphous magnetic material, compared with the case where each magnetic powder is used alone. As a result, the dielectric strength characteristics improved. That is, by mixing the above different magnetic powders, an effect of synergistically increasing the dielectric strength value of the dust core was obtained. In Example 1, the withstand voltage value suddenly increases when the first mixing ratio is in the vicinity of 30% by mass to 40% by mass. In the range of 40% by mass to 70% by mass, the withstand voltage ratio becomes 120% or more and 50% by mass. In the range of ˜70 mass%, the withstand voltage ratio was 130% or more, and the value of the withstand voltage ratio with respect to the single powder of the amorphous magnetic material of Example 1-1 was improved by 30% or more.

(Example 2)
The magnetic powder used in Example 1 is a magnetic powder having a different particle diameter of amorphous magnetic material powder, surface treatment of crystalline magnetic material powder, and different particle diameter, as in Example 1. A toroidal core consisting of a powder core was obtained.
Specifically, an Fe-based amorphous alloy powder having the same composition as in Example 1 and a median diameter D50A of 15 μm was prepared as an amorphous magnetic material powder. In addition, the powder of the amorphous magnetic material used in Example 2 was produced by an atomizing method in which gas atomization and water atomization are continuously performed.
As a powder of crystalline magnetic material, Fe—Si—Cr-based alloy, specifically, Si content is 6-7 mass%, Cr content is 3-4 mass%, the balance is Fe and A powder made of an alloy composed of inevitable impurities and having a median diameter D50C of 4 μm was prepared. The crystalline magnetic material powder used was subjected to phosphate surface insulation treatment.
The pressing force of the pressure molding was 0.5 to 1.5 GPa, and in the heat treatment, heating was performed at 200 to 400 ° C. for 1 hour in a nitrogen atmosphere.

Toroidal cores having different first mixing ratios shown in Table 2 below were produced, and dielectric strength voltage, insulation resistance, core density, magnetic permeability, and iron loss Pcv were measured.
(Test Examples 1 to 5)
The measurement of the withstand voltage, the measurement of the insulation resistance, the measurement of the core density ρ, the measurement of the magnetic permeability, and the measurement of the iron loss Pcv were performed in the same manner as in Example 1.
Dielectric strength ratio (amorphous 100% standard) and crystal as magnetic powder when the dielectric strength value of the toroidal core of Example 2-1 containing only amorphous magnetic material powder is used as the standard (100% amorphous) The dielectric strength ratio (100% crystalline basis) was determined when the dielectric strength value of the toroidal core of Example 2-7 containing only the magnetic material powder was taken as the standard (100%).
As for the magnetic permeability, in addition to the initial magnetic permeability μ0, a relative magnetic permeability μ5500 was measured when a direct current was superimposed on the toroidal coil under the condition of 100 kHz and the DC applied magnetic field was 5500 A / m. The measurement results are shown in Table 2.

  FIG. 6 is a graph showing the dependence of the withstand voltage on the first mixing ratio for Example 2. As shown in the dielectric strength graph of FIG. 6, in Example 2 as well as Example 1, each powder was used alone by mixing the powder of the amorphous magnetic material with the powder of the amorphous magnetic material. Compared with the above, the dielectric strength characteristics were improved and a synergistic effect was recognized. In Example 2, the withstand voltage value is higher than the amorphous magnetic material powder from the first mixing ratio of around 40% by mass, and the withstand voltage ratio is 180% or more in the range of 70% by mass to 90% by mass, The value of the withstand voltage ratio based on the single powder of the amorphous magnetic material of Example 2-6 (100%) was improved by 80% or more.

  FIG. 7 is a graph showing the dependence of the withstand voltage on the first mixing ratio in Example 1 and Example 2. From the results shown in the figure, it is understood that a powder core with higher withstand voltage can be obtained by mixing crystalline magnetic material powder with amorphous magnetic material powder than when each powder is used alone. It was. That is, FIG. 7 is more than expected based on the mixing ratio of the crystalline magnetic material powder and the amorphous magnetic material powder contained in the dust core, that is, synergistic beyond simple additivity. It shows that a dust core having excellent dielectric strength characteristics was obtained due to the effect.

FIG. 8 is a graph showing the withstand voltage ratio at each first mixing ratio when the amorphous magnetic material powder alone is used as a reference in Example 1 and Example 2. FIG. 4 is a graph showing a dielectric strength ratio at each first mixing ratio when a crystalline material powder alone is used as a reference in Example 2.
From the results of FIG. 5 to FIG. 9, the effect of improving the value of the withstand voltage is that the median diameter D ₅₀ A of the amorphous magnetic material is appropriately adjusted and the first mixing ratio is 40 mass% or more and 90 mass% or less. By making it within the range, it is stably produced. In addition, by setting the first mixing ratio to 50 to 70% by mass, the dielectric strength characteristics of the piezoelectric core are improved regardless of whether the median diameter D ₅₀ A of the amorphous magnetic material is large or small. It can be made. Furthermore, with the first mixing ratio (50 to 70% by mass) as shown above from FIG. 9, the dielectric strength with respect to the powder core containing only the crystalline material powder as the magnetic powder is set as the reference (100%). It can be seen that a powder core having a ratio value of 110% or more, or 125% or more can be obtained.

10 to 12 are graphs showing the dependency of the insulation resistance, the core density, and the magnetic permeability on the first mixing ratio in Example 1 in this order.
FIGS. 13 to 15 are graphs showing the dependency of the withstand voltage, the insulation resistance, the core density, and the magnetic permeability on the first mixing ratio in Example 2 in this order.

  As shown in Tables 1 and 2 and FIGS. 5 to 15, the excellent dust core obtained by mixing the powder of the amorphous magnetic material with the powder of the amorphous magnetic material has improved dielectric strength characteristics. Thus, the withstand voltage can be increased without increasing the iron loss Pcv, and a good inductor can be obtained.

  According to the present invention, it is possible to obtain a dust core that provides a good inductor with excellent dielectric strength characteristics and reduced iron loss, and the degree of goodness is the same as the crystalline magnetic material powder contained in the dust core. It was confirmed by this example that the degree exceeded the expectation based on the mixing ratio of the amorphous magnetic material with the powder.

  The inductor having the dust core of the present invention can be suitably used as a component of a booster circuit such as a hybrid vehicle, a component of a power generation / transforming facility, a component of a transformer, a choke coil, or the like.

1 ... Compact core (toroidal core)
DESCRIPTION OF SYMBOLS 10 ... Toroidal coil 2 ... Coated conductive wire 2a ... Coils 2b, 2c ... End 2d, 2e of coated conductive wire 2 ... End 20 of coil 2a ... Coil buried type inductor 21 ... Powder core 22 ... Coated conductive wire 22a, 22b ... Ends 23a, 23b ... Connection end 22c ... Coil part 200 ... Spray dryer device 201 ... Rotor S ... Slurry P ... Granulated powder

Claims (16)

A powder core containing a powder of crystalline magnetic material and a powder of amorphous magnetic material,
The first mixing ratio, which is the mass ratio of the content of the crystalline magnetic material powder to the total content of the crystalline magnetic material powder and the amorphous magnetic material powder, is 40% by mass. A powder core of 90% by mass or less.   The powder core according to claim 1, wherein the first mixing ratio is 50 mass% or more and 70 mass% or less.   The said powder core has a dielectric strength value of 120% or more with reference to the dielectric strength value of a powder core containing only the amorphous magnetic material powder as a magnetic powder (100%). Or the compacting core of 2.   The said dust core is 110% or more, with the dielectric strength value of the dust core containing only the powder of the said crystalline magnetic material as magnetic powder as a reference | standard (100%). 2. The powder core according to 2 or 3.   The crystalline magnetic material is Fe-Si-Cr alloy, Fe-Ni alloy, Fe-Co alloy, Fe-V alloy, Fe-Al alloy, Fe-Si alloy, Fe-Si-Al. The powder core as described in any one of Claim 1 to 4 containing the 1 type, or 2 or more types of material chosen from the group which consists of a system alloy, carbonyl iron, and pure iron.   The dust core according to any one of claims 1 to 5, wherein the crystalline magnetic material is made of an Fe-Si-Cr-based alloy.   The amorphous magnetic material includes one or more materials selected from the group consisting of Fe-Si-B alloys, Fe-PC-C alloys, and Co-Fe-Si-B alloys. The powder core according to any one of claims 1 to 6.   The dust core according to claim 7, wherein the amorphous magnetic material is made of a Fe—P—C alloy.   The powder core according to any one of claims 1 to 8, wherein the powder of the crystalline magnetic material is made of an insulating material.   10. The binder according to claim 1, further comprising a binding component that binds the powder of the crystalline magnetic material and the powder of the amorphous magnetic material to another material contained in the powder core. The dust core according to one item.   The powder core according to claim 10, wherein the binder component includes a component based on a resin material.   12. The method for producing a dust core according to claim 11, comprising pressure molding of a mixture comprising the crystalline magnetic material powder and the amorphous magnetic material powder and a binder component comprising the resin material. A method for producing a powder core, comprising a molding step of obtaining a molded product by a molding process.   The method for producing a dust core according to claim 12, wherein the molded product obtained by the molding step is the dust core.   The manufacturing method of the powder core of Claim 12 provided with the heat processing process of obtaining the said powder core by the heat processing which heats the said molded product obtained by the said shaping | molding process.   It is an inductor provided with the connecting terminal connected to each end part of the dust core, coil, and said coil as described in any one of Claim 1-11, Comprising: At least one part of the said dust core is the said connection. An inductor disposed so as to be located in an induced magnetic field generated by the current when a current is passed through the coil via a terminal.   16. An electronic / electrical device on which the inductor according to claim 15 is mounted, wherein the inductor is connected to a substrate at the connection terminal.