JP2021002535A - Dust core, manufacturing method of dust core, electric/electronic component provided with dust core, and electric/electronic device on which electric/electronic component is mounted - Google Patents

Abstract

To provide a dust core that does not easily change the magnetic properties even when used in a high temperature environment and has excellent mechanical properties, a manufacturing method of the dust core, an electric/electronic component provided with the dust core, and an electric/electronic device on which the electric/electronic component is mounted.SOLUTION: A dust core 1 includes a molded body 1B including a soft magnetic powder MM, and an exterior coat CRM of the molded body 1B. The exterior coat CRM includes at least one of a thermoplastic polyimide and a thermoplastic polyamide-imide and has an impregnated structure.SELECTED DRAWING: Figure 2

Description

The present invention relates to a dust core, a method for manufacturing the dust core, an electric / electronic component provided with the dust core, and an electric / electronic device on which the electric / electronic component is mounted.

Electrical and electronic components such as reactors, transformers, and choke coils are used in power circuits in data center servers, booster circuits such as hybrid vehicles, and electrical and electronic equipment such as power generation and substation equipment. A dust core may be used as a magnetic member in such electric / electronic parts. Such a dust core comprises a molded product obtained by compact molding a large number of soft magnetic powders and heat-treating the obtained molded product.

Since the dust core includes a molded body of soft magnetic powder as described above, it may be provided with an exterior coat from the viewpoint of increasing mechanical strength. In this regard, Patent Document 1 describes a composite magnetic material for an inductor in which a soft magnetic metal powder is bonded with a non-magnetic material, and the non-magnetic material is a molding aid added and mixed with the soft magnetic metal powder. The soft magnetic metal powder / molding aid molded body is heat-treated and then has an impregnated resin impregnated in the soft magnetic metal powder / molding aid molded body as a binder, and the impregnated resin is under atmospheric pressure. A composite magnetic material characterized in that the thermosetting temperature is 180 ° C. or higher is disclosed.

Utility Model Registration No. 3145832

The usage environment of the electric / electronic device provided with the electric / electronic component having the above-mentioned dust core is various, and the dust core is set to 100 ° C. due to reasons such as high outside air temperature and location near the heat generating component. It may be used in a close environment. When used in such a high temperature environment, the material constituting the dust core may be thermally denatured. When the modification of the material changes the magnetic properties of the dust core, particularly the core loss, the amount of heat generated from the dust core increases, which may promote the thermal denaturation of the dust core. There is a concern that changes in the magnetic properties of the dust core based on being used in such a high temperature environment may affect the operational stability of electrical and electronic components having the dust core. Therefore, there is a demand for a dust core whose magnetic characteristics do not easily change even when used in the above-mentioned high temperature environment. It is also required that the mechanical strength of the dust core be maintained within an appropriate range when used in the above-mentioned high temperature environment.

INDUSTRIAL APPLICABILITY According to the present invention, a dust core having excellent mechanical properties and whose magnetic characteristics do not easily change even when used in a high temperature environment, a method for manufacturing the dust core, electric / electronic parts provided with the dust core, and the electricity. -The purpose is to provide electrical and electronic equipment on which electronic components are mounted.

One aspect of the present invention provided to solve the above problems is a polyimide core comprising a molded body containing a soft magnetic powder and an exterior coat of the molded body, wherein the exterior coat is thermoplastic. It is a dust core characterized by containing a thermoplastic resin containing at least one of polyimide and thermoplastic polyamide-imide.

The dust core according to the present invention comprising an exterior coat containing a thermoplastic resin containing at least one of a thermoplastic polyimide and a thermoplastic polyamide-imide contains a conventionally used silicone-based resin (particularly a methylphenyl silicone resin). Compared to the dust core with an exterior coating, the magnetic properties, especially the core loss, even when placed in a high temperature environment (specifically, an environment of 250 ° C.) for a long time (specifically, 100 hours or more). Is hard to change. Moreover, it is possible to maintain practical mechanical strength even when it is left in a high temperature environment for a long time. The exterior coat preferably has an impregnated structure.

In the powder core according to the present invention, the soft magnetic powder may contain at least one powder of an iron-based material and a nickel-based material.

In the powder core according to the present invention, the soft magnetic powder may contain a powder of a crystalline magnetic material. In the powder core according to the present invention, the soft magnetic powder may contain a powder of an amorphous magnetic material. In the powder core according to the present invention, the soft magnetic powder may contain a powder of a nanocrystalline magnetic material. Further, the soft magnetic powder may be a mixture of two or more selected from the crystalline magnetic material, the amorphous magnetic material, and the nanocrystalline magnetic material.

In the powder core according to the present invention, the molded product includes the soft magnetic powder and a binding component, and the binding component is composed of a thermal decomposition residue of a binder component including a resin-based material. You may. When the molded product included in the dust core according to the present invention includes the above-mentioned thermal decomposition residue, voids are likely to occur inside the molded product. In general, a molded product having many voids inside tends to lack the mechanical strength of the molded product. In the dust core according to the present invention, a thermoplastic resin containing at least one of a thermoplastic polyimide and a thermoplastic polyamide-imide can be positioned so as to fill this void, so that the mechanical strength of the molded product is reinforced. To. Further, since the exterior coat is composed of at least one of a thermoplastic polyimide having high heat resistance and a thermoplastic polyamide-imide having little thermal denaturation, it is possible to improve the initial magnetic properties after the exterior coat and to improve the initial magnetic properties of the exterior coat material. Deterioration of magnetic properties in a high temperature environment due to thermal denaturation is suppressed.

Another aspect of the present invention is the method for producing a compact core according to the present invention, wherein a molded product is formed by a molding process including pressure molding of a mixture containing the soft magnetic powder and the binder component. A molding step of obtaining, a heat treatment step of heating a molded product obtained by the molding step to obtain the molded product having the soft magnetic powder and a binding component composed of a thermal decomposition residue of the binder component, and thermoplasticity. A liquid composition containing a thermoplastic resin containing at least one of a polyimide and a thermoplastic polyamideimide and a solvent is brought into contact with the molded product to form a coating film of the liquid composition in a region including the surface of the molded product. A method for producing a dust core, which comprises an exterior coating step of drying a coating film to volatilize a solvent to form an exterior coating containing the thermoplastic resin. According to the above method, it is possible to efficiently produce a dust core containing a binder component composed of a thermal decomposition residue of a binder component.

Another aspect of the present invention is an electrical / electronic component including a dust core, a coil, and connection terminals connected to each end of the coil according to the present invention, at least of the dust core. Some of the electrical and electronic components are arranged 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.

Another aspect of the present invention is an electric / electronic device including the above-mentioned electric / electronic component according to the present invention.

The dust core according to the present invention changes its magnetic properties, particularly core loss, even when it is placed in a high temperature environment (specifically, an environment of 250 ° C.) for a long time (specifically, 100 hours or more). Hateful. Moreover, it is possible to maintain practical mechanical strength even when it is left in a high temperature environment for a long time. Therefore, the dust core according to the present invention is not easily changed in magnetic properties even when used in a high temperature environment, and has excellent mechanical properties. Further, according to the present invention, an electric / electronic component provided with the above-mentioned dust core and an electric / electronic device on which the electric / electronic component is mounted are provided.

It is a perspective view which conceptually shows the shape of the dust core which concerns on one Embodiment of this invention. (A) Schematic diagram of the inside of the molded product after the molding step for producing the dust core according to the embodiment of the present invention and before the heat treatment step, (b) The dust core according to the embodiment of the present invention. A schematic diagram of the inside of the molded body after the heat treatment step for manufacturing the above, and before the exterior coating step, and (c) the dust core after the exterior coating step for manufacturing the dust core according to the embodiment of the present invention. It is a schematic diagram of the inside of. It is a figure which conceptually shows the spray dryer apparatus used in an example of the method of producing granulated powder, and its operation. It is a perspective view which conceptually shows the shape of the toroidal core which is an electronic component which comprises the dust core which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail.
1. 1. Powder core 1 The powder core 1 according to an embodiment of the present invention shown in FIG. 1 has a ring-shaped appearance, and includes a molded body containing soft magnetic powder and an exterior coat of the molded body. The dust core 1 according to an embodiment of the present invention contains a thermoplastic resin in which the outer coat contains at least one of a thermoplastic polyimide and a thermoplastic polyamide-imide. As an example without limitation, the soft magnetic powder is bound to other materials contained in the dust core 1 (the same material may be used or different materials may be used). Contains ingredients. The appearance of the dust core 1 is not limited to the ring shape, and there are, for example, EE type, EI type, ER type, PQ type, I type, or one in which a coil is enclosed inside the dust core.

(1) Molded Body (1-1) Soft Magnetic Powder The soft magnetic powder contained in the molded body of the dust core 1 according to the embodiment of the present invention is an iron-based material containing iron and a nickel-based material containing nickel. May contain at least one powder of.

The soft magnetic powder contained in the molded product of the dust core 1 according to the embodiment of the present invention may contain a powder of a crystalline magnetic material. As used herein, the term "crystalline magnetic material" means a material whose structure is made of crystalline material and is a ferromagnet, particularly a soft magnetic material. The soft magnetic powder contained in the molded product of the dust core 1 according to the embodiment of the present invention may be made of a powder of a crystalline magnetic material. Specific examples of crystalline magnetic materials include Fe—Si—Cr based alloys, Fe—Ni based alloys, Ni—Fe based alloys, Fe—Co based alloys, Fe—V based alloys, Fe—Al based alloys, and Fe—Si. Examples include system alloys, Fe—Si—Al system alloys, carbonyl iron and pure iron.

The soft magnetic powder contained in the molded product of the dust core 1 according to the embodiment of the present invention may contain a powder of an amorphous magnetic material. As used herein, the term "amorphous magnetic material" means a material in which the volume of the amorphous portion in the structure is more than 50% of the total and is a ferromagnet, particularly a soft magnetic material. The soft magnetic powder contained in the molded product of the powder core 1 according to the embodiment of the present invention may be made of a powder of an amorphous magnetic material. Specific examples of the amorphous magnetic material include Fe-Si-B alloys, Fe-PC alloys and Co-Fe-Si-B alloys. The above-mentioned amorphous magnetic material may be composed of one kind of material or may be composed of a plurality of kinds of materials. The magnetic material constituting the powder of the amorphous magnetic material is preferably one kind or two or more kinds of materials selected from the group consisting of the above materials, and among these, the Fe-PC alloy is used. It is preferably contained, and more preferably made of an Fe—PC based alloy.

As specific examples of the Fe-P-C-based alloy of the amorphous magnetic material, composition formula, indicated by _{Fe 100at% -abcxyzt Ni a Sn b} Cr c P x C y B z Si t, 0at% ≤a ≤ 10 at%, 0 at% ≤ b ≤ 3 at%, 0 at% ≤ c ≤ 6 at%, 6.8 at% ≤ x ≤ 13.0 at%, 2.2 at% ≤ y ≤ 13.0 at%, 0 at% ≤ z Examples thereof include Fe-based amorphous alloys having ≦ 9.0 at% and 0 at% ≦ t ≦ 7 at%. In the above composition formula, Ni, Sn, Cr, B and Si are optional additive elements.

The amount a of Ni added is preferably 0 at% or more and 7 at% or less, and more preferably 4 at% or more and 6.5 at% or less. The addition amount b of Sn is preferably 0 at% or more and 2 at% or less, and more preferably 0 at% or more and 1 at% or less. The amount c of Cr added is preferably 0 at% or more and 2.5 at% or less, and more preferably 1.5 at% or more and 2.5 at% or less. In some cases, the addition amount x of P is preferably 8.8 at% or more. The amount y of C added may be preferably 2.2 at% or more and 9.8 at% or less. The addition amount z of B is preferably 0 at% or more and 8.0 at% or less, and more preferably 0 at% or more and 2 at% or less. The addition amount t of Si is preferably 0 at% or more and 6 at% or less, and more preferably 0 at% or more and 2 at% or less.

The soft magnetic powder contained in the molded product of the dust core 1 according to the embodiment of the present invention may contain a powder of a nanocrystalline magnetic material. In the present specification, the "nanocrystal magnetic material" has a nanocrystal structure in which crystal grains having an average crystal grain size of several nm to several tens of nm are uniformly precipitated in a portion exceeding at least 50% of the structure. , Means a material that is a ferromagnetic material, especially a soft magnetic material. The nanocrystal magnetic material may have an amorphous structure other than the nanocrystal grains, or may have a nanocrystal structure. The soft magnetic powder contained in the molded product of the dust core 1 according to the embodiment of the present invention may be made of a powder of a nanocrystalline magnetic material. As a specific example of the nanocrystalline magnetic material, Fe-Cu-M (where M is one or more metal elements selected from Nb, Zr, Ti, V, Mo, Hf, Ta, and W) -Si Examples thereof include −B alloys, Fe—MB alloys, Fe—Cu—MB alloys and the like.

The soft magnetic powder contained in the molded product of the dust core 1 according to the embodiment of the present invention may be composed of one kind of powder or may be a mixture of a plurality of kinds. Specific examples of this mixture include a mixture of two or more of a crystalline magnetic material, an amorphous magnetic material, and a nanocrystalline magnetic material. More specifically, for example, the soft magnetic powder contained in the compact of the dust core 1 according to the embodiment of the present invention is a mixture of a powder of a crystalline magnetic material and a powder of an amorphous magnetic material. It may be a powder of an amorphous magnetic material, and a part thereof may be a powder of a nanocrystalline magnetic material.

The shape of the soft magnetic powder contained in the dust core 1 according to the embodiment of the present invention is not limited. The shape of the soft magnetic powder may be spherical or non-spherical. When it is non-spherical, it may have a shape having shape anisotropy such as scaly, elliptical sphere, droplet shape, or needle shape, or an irregular shape having no particular shape anisotropy. Good. Examples of the amorphous soft magnetic powder include cases where a plurality of spherical soft magnetic powders are bonded in contact with each other or bonded so as to be partially buried in another soft magnetic powder. Such amorphous soft magnetic powder is easily observed when the soft magnetic powder is a powder of carbonyl iron.

The shape of the soft magnetic powder may be a shape obtained at the stage of producing the soft magnetic powder, or may be a shape obtained by secondary processing the produced soft magnetic powder. Examples of the former shape include a spherical shape, an elliptical spherical shape, a droplet shape, and a needle shape, and examples of the latter shape include a scaly shape.

The particle size of the soft magnetic powder contained in the dust core 1 according to the embodiment of the present invention is not limited. If such a particle size is defined by a median diameter D50 (particle size when the volume cumulative value in the volume distribution of the particle size of the soft magnetic powder measured by the laser diffraction scattering method is 50%), it is usually 1 μm to 45 μm. It is considered to be a range. The median diameter D50 of the soft magnetic powder is preferably 2 μm or more and 30 μm or less, preferably 3 μm or more and 15 μm or less, from the viewpoint of improving handleability and increasing the packing density of the soft magnetic powder in the molded product of the dust core 1. It is more preferable that the thickness is 4 μm or more and 13 μm or less.

(1-2) Bundling component The composition of the binding component is not limited as long as it is a material that contributes to fixing the soft magnetic powder contained in the dust core 1 according to the embodiment of the present invention. As the material constituting the binding component, an organic material such as a resin material and a thermal decomposition residue of the resin material (in the present specification, these are collectively referred to as "components based on the resin material"), an inorganic material, etc. Is exemplified. Examples of the resin material include acrylic resin, silicone resin, epoxy resin, phenol resin, urea resin, and melamine resin. A glass-based material such as water glass is exemplified as a binding component composed of an inorganic-based material. The binding component may be composed of one kind of material or may be composed of a plurality of materials. The binding component may be a mixture of an organic material and an inorganic material.

Insulating materials are usually used as the binding component. This makes it possible to improve the insulating property of the dust core 1.

As a specific example, the molded product of the dust core 1 according to the embodiment of the present invention is manufactured by a production method including a molding process including pressure molding of a mixture containing a soft magnetic powder and a binder component. Is. In the present specification, the "binder component" is a component that gives a binder component, and the binder component may be composed of a binder component or a material different from the binder component.

As a specific example of the case where the binder component is different from the binder component, the case where the binder component contained in the molded product of the dust core 1 according to the embodiment of the present invention comprises a thermal decomposition residue of the binder component including a resin-based material. Can be mentioned. In the formation of this pyrolysis residue, a part of the binder component is decomposed and volatilized. Therefore, when the molded body included in the dust core 1 includes the above-mentioned thermal decomposition residue, voids are generated in the molded body, specifically, between the soft magnetic powders located at the most recent positions in the molded body. In some cases.

This point will be described with reference to FIG. FIG. 2A is a schematic view of the inside of the molded product after the molding step for producing the dust core according to the embodiment of the present invention and before the heat treatment step, and FIG. 2B is a schematic view of the inside of the molded product of the present invention. After the heat treatment step for producing the dust core according to one embodiment, FIG. 2C shows the dust core after the exterior coating step for producing the dust core according to one embodiment of the present invention. It is a schematic diagram of the inside. As shown in FIG. 2A, in the molded product 1A obtained through the molding step, the soft magnetic powder MM is bound and fixed by the binder component BM containing the resin-based material. When the heat treatment step is performed on the molded product 1A, as shown in FIG. 2B, thermal decomposition residue TDM is generated by decomposition and volatilization of the binder component BM, and the soft magnetic powder MM of the molded product 1B is produced. It is bound and fixed by the thermal decomposition residue TDM. Therefore, in the molded product 1B, the volume of the void PR increases as compared with the molded product 1A.

Even in such a case, in the polyimide core 1 according to the present invention manufactured by performing a step including an exterior coating step on the molded body 1B, as shown in FIG. 2C, this A material (exterior coating material) CRM that constitutes an exterior coating containing a thermoplastic resin containing at least one of a thermoplastic polyimide and a thermoplastic polyamide-imide can be positioned so as to fill at least a part of the void PR. Therefore, in the dust core 1, the volume of the void PR is reduced, and the soft magnetic powder MM is bound and fixed by the thermal decomposition residue TDM and the exterior coating material CRM to reinforce the mechanical strength. Further, since the exterior coating material CRM uses a thermoplastic resin containing at least one of a thermoplastic polyimide and a thermoplastic polyamide-imide that does not need to be thermoset after coating, the stress due to the thermosetting after the exterior coating is applied to the dust core 1. Not given to. Therefore, the magnetic characteristics of the dust core 1 obtained by the exterior coating step are maintained or improved. Further, since the exterior coating material CRM uses a thermoplastic resin containing at least one of the thermoplastic polyamide-imides with little heat modification, even if the dust core 1 is placed in a high temperature environment, the heat of the exterior coating material CRM is used. Deterioration of the magnetic properties of the dust core 1 due to modification is suppressed.

(2) Exterior coat The dust core 1 according to the embodiment of the present invention includes an exterior coat. The exterior coat is a layer provided so as to cover at least a part of the molded body 1B for the purpose of improving the mechanical strength of the molded body 1B. Since the molded body 1B is formed by press-molding a mixture containing the soft magnetic powder MM, the surface thereof may have irregularities derived from the soft magnetic powder. Further, when the mixture contains the binder component BM and the molded product 1B contains the thermal decomposition residue TDM of the binder component BM, the molded product may have a void PR as described above. In such a case, as shown in FIG. 2C, the exterior coating material CRM may exist not only on the surface of the molded body 1B but also in a region inside from the surface to some extent. That is, in the powder core 1 according to the embodiment of the present invention, it is preferable that the exterior coat has an impregnation structure with respect to the molded body 1B.

The exterior coat included in the dust core 1 according to the embodiment of the present invention contains a thermoplastic resin containing at least one of a thermoplastic polyimide and a thermoplastic polyamide-imide. An example of an unlimited manufacturing method of such an exterior coat is as follows. First, a liquid composition containing a thermoplastic resin containing at least one of a thermoplastic polyimide and a thermoplastic polyamide-imide (abbreviated as "thermoplastic resin" in the following description) and a solvent is prepared. The concentration of the thermoplastic resin in the liquid composition is not limited, but the ease of preparation (easiness of dissolving the thermoplastic resin), the handleability (viscosity), and the thickness of the coating film formed on the molded product 1B are appropriate. Considering the range, the concentration of the thermoplastic resin in the liquid composition is preferably 1% by mass or more and 40% by mass or less, and more preferably 5% by mass or more and 20% by mass or less. The type of solvent is arbitrary as long as the thermoplastic resin can be dissolved. A mixed solvent of an aprotic polar solvent such as N-methylpyrrolidone, methylethylketone or butyl acetate and an aromatic solvent such as xylene or toluene may be preferable. The liquid composition may contain a resin or filler other than the thermoplastic resin as long as the object of the present invention can be achieved. In the following description, a case where the liquid composition contains only the thermoplastic polyimide or the thermoplastic polyamide-imide as the thermoplastic resin as the solid content is taken as a specific example.

Next, the prepared liquid composition is brought into contact with the above-mentioned molded body 1B to form a coating film of the liquid composition in a region including the surface of the molded body 1B. The contact method is arbitrary. The simplest method is to immerse the molded product 1B in the liquid composition for a predetermined time (for example, 5 to 30 minutes). Alternatively, the liquid composition may be sprayed onto the molded product 1B. The atmosphere at the time of contacting the liquid composition with the molded product 1B may be reduced. The amount of the liquid composition applied and the thickness of the coating film formed by contact are arbitrary. Since the molded product 1B has the void PR as described above, the liquid composition can be easily impregnated into the inside of the molded product 1B by contacting the molded product 1B in a reduced pressure atmosphere or lowering the viscosity of the liquid composition.

Subsequently, the coating film formed on the molded body 1B is dried to volatilize the solvent. The drying temperature and time are appropriately set according to the type of solvent. By way of example without limitation, it is about 20 minutes to 5 hours at 60 ° C. to 170 ° C. It may be preferable to perform stepwise heating.

The exterior coat provided in the dust core 1 according to the embodiment of the present invention contains a thermoplastic resin, and in a preferred embodiment, it is made of a thermoplastic resin. Therefore, when the dust core 1 is placed in an environment of 250 ° C. Even so, changes in magnetic properties are unlikely to occur. Specifically, the rate of increase in core loss when left in the above environment for 200 hours can be set to 10% or less. In addition, the rate of decrease in relative magnetic permeability when left in the above environment for 200 hours can be set to 6% or less (the rate of change can be set to -6% or more).

The exterior coat provided in the dust core 1 according to the embodiment of the present invention contains a thermoplastic resin, and in a preferred embodiment, it is made of a thermoplastic resin. Therefore, when the dust core 1 is placed in an environment of 250 ° C. Even so, the decrease in mechanical strength is unlikely to occur. Specifically, the initial ring strength can be set to 15 MPa or more, and the ring strength can be set to 15 MPa or more even when the product is left in the above environment for 200 hours.

(3) Method for Producing Dust Core 1 The method for producing the dust core 1 according to the above embodiment of the present invention is not particularly limited, but if the manufacturing method described below is adopted, the dust core 1 is made more efficient. Is realized.

The method for producing the dust core 1 according to the embodiment of the present invention may include a molding step and an exterior coating step described below, and may further include a heat treatment step.

(3-1) Molding Step First, a mixture containing a soft magnetic powder and a binder component is prepared. A molded product 1A can be obtained by a molding process including pressure molding of this mixture. The pressurizing conditions are not limited and are appropriately determined based on the composition of the binder component and the like. For example, when the binder component is made of a thermosetting resin, it is preferable to heat it together with pressurization to allow the resin curing reaction to proceed 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 pressurization is performed for a short time.

Hereinafter, a case where the mixture is a granulated powder and compression molding is performed will be described in some detail. Since the granulated powder is excellent in handleability, the workability of the compression molding process, which has a short molding time and excellent productivity, can be improved.

(3-1-1) Granulation powder The granulation powder contains a soft magnetic powder and a binder component. The content of the binder component in the granulated powder is not particularly limited. If the content is excessively low, it becomes difficult for the binder component to retain the soft magnetic powder. When the content of the binder component is excessively low, in the powder core 1 obtained through the heat treatment step, the binding component composed of the thermal decomposition residue of the binder component may be a plurality of soft magnetic powders. It becomes difficult to insulate from. On the other hand, when the content of the binder component is excessively high, the content of the binder component contained in the dust core 1 obtained through the heat treatment step tends to be high. When the content of the binding component in the dust core 1 is high, the magnetic characteristics of the dust core 1 are likely to deteriorate due to the influence of the stress that the soft magnetic powder receives from the binding component. Further, when the content of the binder component is excessively high, the space filling rate of the soft magnetic powder of the dust core 1 decreases, and the magnetic characteristics of the powder core 1 tend to decrease. 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 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 are deteriorated, the content of the binder component in the granulated powder is 0.5% by mass or more with respect to the entire granulated powder. The amount is preferably 5% by mass or less, and more preferably 0.6% by mass or more and 3.0% by mass or less.

The granulated powder may contain a material other than the above-mentioned soft magnetic powder and binder component. Examples of such materials include lubricants, silane coupling agents, insulating fillers and the like. When the lubricant is contained, 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 dust core 1.

The method for producing the granulated powder is not particularly limited. The component that gives the above-mentioned granulated powder may be kneaded as it is, and the obtained kneaded product may be pulverized by a known method to obtain the granulated powder, or a solvent (solvent / dispersion medium, Water may be mentioned as an example) to prepare a slurry, and the slurry may be dried and pulverized to obtain granulated powder. The particle size distribution of the granulated powder may be controlled by sieving or classifying after pulverization.

An example of a method for obtaining 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 from the upper part of the device toward the rotor 201. The rotor 201 is rotating at a predetermined rotation speed, and the slurry S is sprayed as droplets 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 while maintaining the droplet shape. As a result, granulated powder P is formed from the slurry S. The granulated powder P is collected from the lower part of the spray dryer device 200.

Each parameter such as the rotation speed of the rotor 201, the temperature of hot air introduced into the spray dryer device 200, and the temperature of the lower part of the chamber may be appropriately set. Specific examples of the setting range of these parameters include 4000 to 6000 rpm as the rotation speed of the rotor 201, 130 to 170 ° C as the hot air temperature to be introduced into the spray dryer device 200, and 80 to 90 ° C as the temperature of the lower part of the chamber. .. Further, the atmosphere in the chamber and its pressure may be appropriately set. As an example, it is possible to set the inside of the chamber as an air atmosphere and set the pressure to ₂ mmH ₂ O (about 0.02 kPa) by the pressure difference from the atmospheric pressure. The particle size distribution of the obtained granulated powder P may be further controlled by sieving or the like.

(3-1-2) Pressurization conditions The pressurization conditions in compression molding are not particularly limited. It may be appropriately set in consideration of the composition of the granulated powder, the shape of the molded product 1A, and the like. If the pressing force during compression molding of the granulated powder is excessively low, the mechanical strength of the molded product 1A decreases. For this reason, problems such as a decrease in the handleability of the molded product 1A and a decrease in the mechanical strength of the dust core 1 obtained from the molded product 1A are likely to occur. In addition, the magnetic characteristics of the dust core 1 may be lowered or the insulating property may be lowered. On the other hand, if the pressing force when compression molding the granulated powder is excessively high, it becomes difficult to produce a molding die that can withstand the pressure.

When the granulated powder is compression-molded from the viewpoint of more stably reducing the possibility that the compression and pressurization process adversely affects the mechanical properties and magnetic properties of the dust core 1 and facilitating industrial mass production. The pressing force may be 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 0.5 GPa or more and 1.8 GPa or less. There is.

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

(3-2) Heat Treatment Step The molded product 1A obtained in the molding step may be the molded product 1B included in the dust core 1 according to the present embodiment, or may be the molded product 1A as described below. On the other hand, a heat treatment step may be carried out to obtain a molded product 1B.

In the heat treatment step, the molded product 1A obtained in the above molding step is heated to adjust the magnetic properties by correcting the distance between the soft magnetic powders, and the strain applied to the soft magnetic powder in the molding step is applied. The molded product 1B is obtained by relaxing and adjusting the magnetic properties.

Since the purpose of the heat treatment step is to adjust the magnetic characteristics of the molded product 1B as described above, the heat treatment conditions such as the heat treatment temperature are set so that the magnetic characteristics of the molded product 1B are the best. As an example of the method of setting the heat treatment conditions, the heating temperature of the molded product 1A may be changed, and other conditions such as the heating rate and the holding time at the heating temperature may be constant.

The evaluation criteria for the magnetic properties of the molded product 1B when setting the heat treatment conditions are not particularly limited. As a specific example of the evaluation item, the core loss of the molded product 1B can be mentioned. In this case, the heating temperature of the molded product 1A may be set so that the core loss of the molded product 1B is minimized. The measurement conditions for core loss are appropriately set, and one example is a condition in which the frequency is 100 kHz and the maximum magnetic flux density is 100 mT.

The atmosphere during the heat treatment is not particularly limited. In the case of an oxidizing atmosphere, the possibility that the thermal decomposition of the binder component proceeds excessively and the possibility that the oxidation of the soft magnetic powder progresses increases, so that the inert atmosphere such as nitrogen and argon and the reduction of hydrogen and the like increase. It is preferable to perform the heat treatment in a sexual atmosphere.

(3-3) Exterior coating step Heat is applied to the molded product 1B made of the molded product 1A obtained by the above molding step, or the molded product 1B obtained by the above heat treatment step for the molded product 1A. Apply an exterior coat containing a plastic resin. Since an example of the manufacturing method is as described above, the description thereof is omitted here.

2. 2. Electrical / Electronic Components The electrical / electronic components according to the embodiment of the present invention include the dust core according to the embodiment of the present invention described above. Specifically, the electrical / electronic component according to the embodiment of the present invention includes a dust core, a coil, and connection terminals connected to the respective ends of the coil. Here, at least a part of the dust core is arranged so as to be located in an induced magnetic field generated by this current when a current is passed through the coil through the connection terminal.

An example of such an electric / electronic component is the toroidal coil 10 shown in FIG. The toroidal coil 10 includes a coil 2a formed by winding a coated conductive wire 2 around a ring-shaped dust 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 composed of the wound conductive wire 2 and the ends 2b and 2c of the coated conductive wire 2. As described above, the electric / electronic component according to the present embodiment may be composed of the same member as the member constituting the coil and the member constituting the connection terminal. Further, the present invention is not limited to the ring-shaped dust core 1 as described above, and for example, an EE type, EI type, ER type, PQ type, or I type dust core with a coil winding or a coil is pressed. Examples thereof include those enclosed inside the powder core.

Since the electrical / electronic component according to the embodiment of the present invention includes the dust core according to the embodiment of the present invention described above, the electrical / electronic component is long in a high temperature environment (specifically, an environment at 250 ° C.). Even if it is left for a period of time (specifically, 100 hours or more), deterioration of the characteristics of electrical and electronic components due to changes in the magnetic characteristics of the dust core is unlikely to occur. In addition, since the dust core can maintain practical mechanical strength even if it is left in the above environment for a long time, the manufacturing process of electric / electronic parts using the dust core, and the electric / electronic parts are electrically / electronic. During the process of mounting or incorporating as part of equipment, and when using the obtained electrical and electronic equipment, external mechanical loads such as collisions with other parts and thermal stress due to sudden temperature changes Even if such a problem occurs, it is unlikely that the electrical and electronic parts will be damaged.

Examples of the electric / electronic component according to the embodiment of the present invention include a reactor, a transformer, a choke coil, and the like in addition to the toroidal coil 10 described above.

3. 3. Electrical / Electronic Equipment The electrical / electronic equipment according to the embodiment of the present invention includes the electrical / electronic component including the dust core according to the embodiment of the present invention described above. Specifically, the one in which the above-mentioned electric / electronic parts are mounted and the one in which the above-mentioned electric / electronic parts are incorporated are exemplified. As a further specific example of such electric / electronic equipment, a switching power supply device equipped with a voltage buck-boost circuit, a smoothing circuit, a DC-DC converter, an AC-DC converter, etc., a power control unit used for solar power generation, etc. Can be mentioned.

Since the electrical / electronic component according to the embodiment of the present invention includes the electrical / electronic component including the dust core according to the embodiment of the present invention, it is in a high temperature environment (specifically, an environment at 250 ° C.). Even if it is left for a long time (specifically, 100 hours or more), malfunctions due to deterioration or breakage of the magnetic properties of the dust core are unlikely to occur. Therefore, the electrical / electronic components according to the embodiment of the present invention are excellent in reliability.

The embodiments described above are described for facilitating the understanding of the present invention, and are 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.

Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

(Example 1)
(1) Preparation of Fe-based amorphous alloy powder Using the water atomization method, Fe _{74.3 at%} Cr _{1.56 at%} P _{8.78 at%} C _{2.62 at%} B _{7.57 at%} Si _{4.19 at%} A powder of an amorphous magnetic material obtained by weighing so as to have a composition was prepared as a soft magnetic powder. The particle size distribution of the obtained soft magnetic powder was measured by volume distribution using a Microtrack particle size distribution measuring device (“MT3300EX” manufactured by Nikkiso Co., Ltd.). As a result, the median diameter (D50), which is the particle size of 50% in the volume distribution when the cumulative volume value in the volume distribution is 50%, was 11 μm.

(2) Preparation of granulated powder 98.1 parts by mass of the above soft magnetic powder, 0.8 parts by mass of an insulating binder made of acrylic resin, 0.6% by mass of a silane coupling agent and zinc stearate. A slurry containing 0.6 parts by mass of a lubricant composed of the above and using water as a solvent was prepared.

The obtained slurry was spray-dried with a spray dryer device (“D350AT-24HOP” manufactured by Pris) to obtain granulated powder. The particle size distribution of the obtained granulated powder was measured by volume distribution using a laser diffraction scattering method particle size distribution measuring device (“LS 13 320” manufactured by Beckman Coulter). As a result, the median diameter (D50), which is the particle size of 50% in the particle size volume distribution when the volume cumulative value in the volume distribution of the measured particle size of the granulated powder is 50%, was 85 μm.

(3) Compression molding The obtained granulated powder is filled in a mold and pressure-molded at a surface pressure of 0.5 to 2 GPa to form a ring shape having an outer diameter of 20 mm, an inner diameter of 12.8 mm, and a thickness of 6.8 mm. A molded product 1A having was obtained.

(4) Heat treatment The obtained molded product 1A is placed in a furnace in a nitrogen air flow atmosphere, and the temperature inside the furnace is 300, which is the optimum core heat treatment temperature from room temperature (23 ° C) to a heating rate of 10 ° C / min. It was heated to ~ 500 ° C., held at this temperature for 1 hour, and then heat-treated to cool to room temperature in a furnace to obtain a molded product 1B.

(5) Exterior Coated Thermoplastic Polyimide (“Q-VR-X1444” manufactured by PI Giken Co., Ltd.) is dissolved in N-methylpyrrolidone (NMP) to prepare a liquid composition having a thermoplastic polyimide concentration of 10% by mass. Prepared.

The above-mentioned molded product 1B was immersed in the obtained liquid composition for 15 minutes. Then, the molded product 1B is taken out from the liquid composition and dried at 80 ° C. for 30 minutes, then at 150 ° C. for 1 hour and at 250 ° C. for 1 hour, and the surface of the molded product 1B is coated with the liquid composition. Was formed, and a dust core 1 having an exterior coat on the molded body 1B was obtained.

(Example 2)
When preparing the liquid composition, thermoplastic polyamide-imide (“HR-11NN” manufactured by Toyobo Co., Ltd.) was dissolved by NMP to prepare a liquid composition having a concentration of thermoplastic polyamide-imide of 10% by mass. A dust core 1 was obtained in the same manner as in Example 1 except for the above.

(Example 3)
Mold 1B was obtained in the same manner as in Example 1. Different types of thermoplastic polyamide-imide (“HL-1210” manufactured by Hitachi Chemical Co., Ltd.) were dissolved in bis (2-methoxyethyl) ether to prepare a liquid composition having a concentration of thermoplastic polyamide-imide of 10% by mass. A dust core 1 was obtained in the same manner as in Example 1 except for the above.

(Example 4)
Mold 1B was obtained in the same manner as in Example 1. A phenol-modified alkyd resin (“H550” manufactured by Meiden Chemical Co., Ltd.) was dissolved in xylene to prepare a liquid composition having a concentration of the phenol-modified alkyd resin of 10% by mass. The above-mentioned molded product 1B was immersed in the obtained liquid composition for 15 minutes. Then, the molded product 1B was taken out from the liquid composition and heated at 45 ° C. for 1 hour and then at 155 ° C. for 1 hour to obtain a dust core 1 having an exterior coat on the molded product 1B.

(Example 5)
Mold 1B was obtained in the same manner as in Example 1. A mixture of polyamide-imide (“V-8000BM” manufactured by DIC) and bisphenol A type epoxy resin (“850-S” manufactured by DIC) in an equivalent amount is diluted with cyclohexanone as a solvent to have a solid content concentration of 12% by mass. A liquid composition was prepared. The above-mentioned molded product 1B was immersed in the obtained liquid composition for 15 minutes. Then, the molded product 1B was taken out from the liquid composition and dried at 100 ° C. for 1 hour to form a coating film of the liquid composition on the surface of the molded product 1B. The molded body 1B provided with this coating film was heated at 200 ° C. for 1 hour to obtain a dust core 1 having an exterior coat on the molded body 1B.

(Example 6)
When preparing the liquid composition, instead of polyamide-imide and bisphenol A type epoxy resin, methylphenyl silicone (“KR-271” manufactured by Shin-Etsu Chemical Co., Ltd.) is diluted with xylene as a solvent to obtain the concentration of methylphenyl silicone. A powder core was obtained in the same manner as in Example 5 except that a liquid composition having a content of 20% by mass was prepared.

(Example 7)
When preparing a liquid composition, different types of methylphenyl silicone (“KR-300” manufactured by Shin-Etsu Chemical Co., Ltd.) are diluted with xylene as a solvent, and the concentration of methylphenyl silicone is 10% by mass. A dust core was obtained in the same manner as in Example 6 except that the above was prepared.

(Example 8)
Mold 1B was obtained in the same manner as in Example 1. Phenylsilicone (“ASP-2010” manufactured by Shin-Etsu Chemical Co., Ltd.) was diluted with xylene to prepare a liquid composition having a solid content concentration of 20% by mass. The above-mentioned molded product 1B was immersed in the obtained liquid composition for 15 minutes. Then, the molded product 1B was taken out from the liquid composition and dried at 100 ° C. for 2 hours to form a coating film of the liquid composition on the surface of the molded product 1B. The molded body 1B provided with this coating film was heated at 150 ° C. for 5 hours to obtain a dust core 1 having an exterior coat on the molded body 1B.

(Example 9)
When preparing the liquid composition, modified silicone (“SCR-1012” manufactured by Shin-Etsu Chemical Co., Ltd.) was diluted with xylene as a solvent to prepare a liquid composition having a concentration of methylphenyl silicone of 10% by mass. A dust core was obtained in the same manner as in Example 8 except for the above.

(Example 10)
Mold 1B was obtained in the same manner as in Example 1. A thermosetting polyimide (“UPIA-AT” manufactured by Ube Industries, Ltd.) was diluted with NMP to prepare a liquid composition having a solid content concentration of 10% by mass. The above-mentioned molded product 1B was immersed in the obtained liquid composition for 15 minutes. Then, the molded product 1B was taken out from the liquid composition and dried at 80 ° C. for 30 minutes and then at 150 ° C. for 1 hour to form a coating film of the liquid composition on the surface of the molded product 1B. The molded body 1B provided with this coating film was heated at 350 ° C. for 1 hour in a nitrogen atmosphere to obtain a powder core 1 having an exterior coat on the molded body 1B.

(Example 11)
When preparing a liquid composition, different types of thermosetting polyimide (“Uimide CR” manufactured by Unitica) are diluted with NMP as a solvent, and the concentration of the thermosetting polyimide is 10% by mass. A polyimide core 1 was obtained in the same manner as in Example 10 except that the product was prepared.

(Reference example 1)
A dust core 1 made of a molded product 1B obtained in the same manner as in Example 1 was obtained. That is, the dust core 1 according to Reference Example 1 did not have an exterior coat.

(Test Example 1) Measurement of relative magnetic permeability and its rate of change A toroidal core was obtained by winding a copper wire around the dust core 1 produced according to Examples and Reference Examples. For this toroidal core, the relative magnetic permeability at a frequency of 100 kHz was measured using an impedance analyzer (“4192A” manufactured by HP). This relative magnetic permeability is called "initial relative magnetic permeability μ ₀ ".
The dust core 1 produced in Examples and Comparative Examples was allowed to stand in an environment of 250 ° C. for 200 hours, and the relative magnetic permeability of the dust core 1 after standing was measured in the same manner as described above. This relative magnetic permeability is referred to as "after heating specific magnetic permeability μ ₁ ".
The rate of change of relative magnetic permeability Rμ (unit:%) was calculated by the following formula.
Rμ = (μ ₁ − μ ₀ ) / μ ₀ × 100
Table 1 shows the initial relative permeability μ _{0, the} relative permeability μ ₁ after heating, and the rate of change Rμ of the relative permeability. Table 1 shows the resin type and concentration (unit: mass%) of the liquid composition used in the examples.

(Test Example 2) Measurement of core loss and its rate of change A toroidal coil 10 was obtained by winding a copper wire around the dust core 1 produced in Examples and Reference Examples. The core loss (PCV) of this toroidal coil 10 was measured using a BH analyzer (“SY-8218” manufactured by Iwatsu Electric Co., Ltd.) under the conditions of a frequency of 100 kHz and a maximum magnetic flux density of 100 mT. This core loss is called "initial core loss W ₀ " (unit: kW / m ³ ).
The dust core 1 produced in Examples and Comparative Examples was allowed to stand in an environment of 250 ° C. for 200 hours, and the core loss of the dust core 1 after standing was measured in the same manner as described above. This core loss is called "core loss after heating W ₁ " (unit: kW / m ³ ).
The rate of change RW (unit:%) of core loss was calculated by the following formula.
RW = (W ₁ −W ₀ ) / W ₀ × 100
Table 1 shows the initial core loss W _{0, the} core loss W ₁ after heating, and the rate of change RW of the core loss.

(Test Example 3) Measurement of pressure ring strength and its rate of change The powder core 1 produced in Examples and Reference Examples was measured by a test method based on JIS Z2507: 2000, and the initial pressure ring strength S ₀ (unit: MPa). ) Was asked.
The dust core 1 separately prepared according to Examples and Comparative Examples was allowed to stand in an environment of 250 ° C. for 200 hours, and the powder core 1 after standing was measured by a test method based on JIS Z2507: 2000. The pressure ring strength S ₁ (unit: MPa) after heating was determined.
The rate of change RS (unit:%) of the annulus strength was calculated by the following formula.
RS = (S ₁ −S ₀ ) / S ₀ × 100
Table 1 shows the initial ring strength S _{0, the} after-heating pressure ring strength S _1, and the rate of change RS of the pressure ring strength.

As shown in Table 1, the dust core 1 according to the examples of the present invention (Examples 1 to 3) has a change rate of the relative magnetic permeability of − even after being placed in an environment of 250 ° C. for 200 hours. The rate of decrease was 6% or more (the rate of decrease was 6% or less), the rate of change in core loss was within ± 10%, and the ring strength was 15 MPa or more even after heating.
On the other hand, the dust core 1 according to Comparative Examples (Examples 4 to 11) and Reference Example (Reference Example 1) has a decrease rate of relative magnetic permeability of 6% or less and an increase rate of core loss of 10% or less. , And at least one of both the initial annulus strength and the after-heated annulus strength of 15 MPa or more, it was not possible to have particularly excellent properties in terms of both magnetic properties and mechanical strength.

The electronic component using the dust core of the present invention can be suitably used as a booster circuit of a hybrid vehicle or the like, a reactor used in power generation or substation equipment, a transformer, a choke coil, or the like.

1 ... Powder core 1A ... Molded product 1B ... Molded body MM ... Soft magnetic powder BM ... Binder component TDM ... Thermal decomposition residue PR ... Void CRM ... Exterior coating material 10 ... Toroidal coil 2 ... Coated conductive wire 2a ... Coil 2b, 2c ... Ends 2d, 2e of coated conductive wire 2 ... Ends 200 of coil 2a ... Spray dryer device 201 ... Rotor S ... Slurry P ... Granulated powder

Claims (11)

A powder core comprising a molded body containing a soft magnetic powder and an exterior coat of the molded body.
The exterior coat is a dust core comprising a thermoplastic resin containing at least one of a thermoplastic polyimide and a thermoplastic polyamide-imide. The dust core according to claim 1, wherein the exterior coat has an impregnated structure. The dust core according to claim 1 or 2, wherein the soft magnetic powder contains at least one powder of an iron-based material and a nickel-based material. The dust core according to any one of claims 1 to 3, wherein the soft magnetic powder contains a powder of a crystalline magnetic material. The dust core according to any one of claims 1 to 4, wherein the soft magnetic powder contains a powder of an amorphous magnetic material. The dust core according to any one of claims 1 to 5, wherein the soft magnetic powder contains a powder of a nanocrystalline magnetic material. The method according to any one of claims 1 to 6, wherein the soft magnetic powder is a mixture of two or more of the crystalline magnetic material, the amorphous magnetic material, and the nanocrystalline magnetic material. Powder core. The molded product comprises the soft magnetic powder and a binding component, and the binding component comprises a thermal decomposition residue of a binder component containing a resin-based material, according to any one of claims 1 to 7. The described dust core. The method for producing a dust core according to claim 8.
A molding step of obtaining a molded product by a molding process including pressure molding of a mixture containing the soft magnetic powder and the binder component.
A heat treatment step of heating a molded product obtained by the molding step to obtain the molded product having the soft magnetic powder and a binding component composed of a thermal decomposition residue of the binder component, and a thermoplastic polyimide and thermoplastic. A liquid composition containing a thermoplastic resin containing at least one of polyamideimide and a solvent is brought into contact with the molded product to form a coating film of the liquid composition in a region including the surface of the molded product, and the coating film is dried. A method for producing a dust core, which comprises an exterior coating step of forming an exterior coating containing the thermoplastic resin by volatilizing the solvent. An electrical / electronic component comprising the dust core, the coil according to any one of claims 1 to 8, and connection terminals connected to the respective ends of the coil.
At least a part of the dust core is arranged so as to be located in an induced magnetic field generated by the current when a current is passed through the coil through the connection terminal. parts. An electrical / electronic device comprising the electrical / electronic component according to claim 10.