JP2010245216A - Magnetic powder material, granulating powder, compact, baked object for magnetic core, and method of manufacturing electromagnetic component and baked object for magnetic core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a magnetic powder material for acquiring a high-density baked object capable of improving permeability for use in a magnetic core; granulating powder; and compact. <P>SOLUTION: The magnetic powder material includes soft magnetic powder containing fine particles and coarse grains with different particle sizes, and insulating layers consisting of inorganic matters whose principal ingredient is silicon oxide formed at least in the outer peripheral surface of coarse grains. It is preferable that the magnetic powder material includes insulating layers composed of inorganic matters whose main ingredient is silicon oxide existing only in coarse grains. As insulating layers composed of inorganic matters whose main ingredient is silicon oxide with excellent rigidity are formed at least in coarse grains, insulation between large coarse grains which have a large impact on iron loss can be reliably secured. Using the soft magnetic powder combining fine particles and coarse grains, it is possible to obtain compacts and baked objects where fine particles have penetrated into gaps between coarse grains, thereby producing baked objects of high density and high permeability. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a magnetic powder material, a granulated powder using the powder material, a molded body using the granulated powder, a sintered body for a magnetic core made of the molded body, an electromagnetic component using the sintered body for a magnetic core, and a magnetic core The present invention relates to a method for producing a fired body.

  Inductors such as choke coils are used in circuits that convert energy, such as switching power supplies and DC / DC converters. As an example of a configuration of an inductor, one having a magnetic core obtained by firing a powder compact of soft magnetic powder and a coil configured by winding a winding around the outer periphery of the magnetic core is known.

  For example, Patent Document 1 discloses a method for manufacturing a magnetic core as follows. First, a silicone resin is mixed with an irregularly shaped soft magnetic powder having a particle size of 5 to 70 μm, and the mixture is heated in the range of 100 ° C. to 130 ° C. to form an insulating coating of silicone oxide on the soft magnetic powder. Then, the soft magnetic powder having the silicone oxide insulating film formed thereon is pressure-molded into a predetermined shape and heat-treated at 500 ° C. to 700 ° C. to produce a magnetic core.

  According to the magnetic core obtained by such a method, the insulation between the soft magnetic powders is ensured by the insulating coating made of silicone oxide, and even if a large direct current is superimposed, the inductance is not extremely reduced.

Japanese Patent Laid-Open No. 2004-319652

  Inductor magnetic cores are required to increase magnetic permeability and to reduce iron loss by suppressing the generation of eddy currents. However, the conventional magnetic core is still insufficient for such a demand.

  In general, the green compact can increase the magnetic permeability by increasing its density. However, Patent Document 1 only discloses the use of soft magnetic powder having a particle size of 5 to 70 μm. Usually, such a powder has a certain particle size distribution around a certain average particle size. Therefore, only a compacted body in which various particles of coarse to coarse particles in this distribution are mixed at random can be obtained, and it is difficult to improve the density of the molded body, that is, to improve the magnetic permeability. .

  Moreover, in order to reduce an iron loss, it is calculated | required that the particles of soft-magnetic powder are insulated reliably. However, in the technique of Patent Document 1, the heat treatment temperature of the mixture of the soft magnetic powder and the silicone resin is as low as 100 ° C. to 130 ° C., and at such a heat treatment temperature, the ratio of the silicone resin converted into silicon oxide is considerably low. As a result, the insulation film formed on the outer periphery of the soft magnetic powder cannot obtain sufficient hardness, and the insulation film breaks due to the contact between the powders during the pressure forming of the molded body, and the soft magnetic powder is sufficiently insulated from each other. Difficult to do. In particular, when the soft magnetic powder has such a rigidity that it is not substantially deformed by the pressure at the time of molding, the insulating coating with a low hardness remaining in the silicone resin state is likely to break.

  The present invention has been made in view of the above circumstances, and one of its purposes is to obtain a sintered body for a magnetic core which can improve magnetic permeability at a high density and reduce iron loss by insulating treatment of soft magnetic powder. It is in providing a magnetic powder material, granulated powder, and a molded object.

  Another object of the present invention is to provide a sintered core for a magnetic core that has a high density, a high magnetic permeability, and can reduce iron loss by insulating a soft magnetic powder, a method for manufacturing the same, and an electromagnetic component using the sintered core for a magnetic core. There is to do.

[Magnetic powder material]
The magnetic powder material of the present invention is composed of a soft magnetic powder containing fine particles and coarse particles having different particle diameters, and an inorganic substance mainly composed of silicon oxide formed on the outer peripheral surface of at least the coarse particles of the soft magnetic powder. And an insulating layer.

  According to this configuration, it is possible to reliably ensure insulation between coarse grains having a large influence on iron loss by forming at least coarse grains of an inorganic insulating layer mainly composed of silicon oxide having excellent rigidity. it can. In addition, by using soft magnetic powder in which fine particles and coarse particles are combined, it is possible to obtain compacts and fired bodies in which fine particles enter the gaps between the coarse particles, producing high-density and high magnetic permeability fired bodies. it can.

  In the magnetic powder material of the present invention, it is preferable that only the coarse particles have an insulating layer made of an inorganic material mainly composed of silicon oxide.

  According to this configuration, a sintered body having a high magnetic permeability and a low iron loss can be easily obtained by providing an insulating layer made of an inorganic material mainly composed of silicon oxide only on coarse particles.

  In the magnetic powder material of the present invention, the soft magnetic powder is preferably at least one of an Fe—Si—Al alloy, an Fe—Si alloy, and an Fe—Al alloy.

  In the soft magnetic powder having such a composition, the soft magnetic powder is not substantially deformed by the compression force when the magnetic powder material is formed. Therefore, with such a high-rigidity soft magnetic powder, damage to the insulating layer due to the deformation of the powder can be avoided as much as possible even if it has a high-hardness insulating layer.

  In the magnetic powder material of the present invention, the fine particles preferably have a maximum particle size of less than 40 μm, the coarse particles have a minimum particle size of 40 μm or more, and a maximum particle size of 150 μm or less.

  By limiting the maximum particle size of the powder in this manner, eddy current loss in the powder particles, which is generated in proportion to the square of the particle size, can be kept low.

  In the magnetic powder material of the present invention, the constituent material of the soft magnetic powder preferably has a Vickers hardness HV0.1 of 300 or more. “HV0.1” indicates that the load of the indenter during the test is 0.1 kgf.

  According to this configuration, the soft magnetic powder is not substantially deformed by the compressive force when the magnetic powder material is molded. Therefore, with such a high-rigidity soft magnetic powder, damage to the insulating layer due to the deformation of the powder can be avoided as much as possible even if it has a high-hardness insulating layer.

[Granulated powder]
The granulated powder of the present invention is a granulated powder that is formed into a molded body by pressurization and is fired for a magnetic core by firing the molded body, and the magnetic powder material of the present invention and a binder during the firing And a firing resin for retaining the fired body after firing. The magnetic powder material and the firing resin are integrated into a granular form.

  According to the granulated powder of this configuration, it is possible to obtain a molded body with high density and coarse particles insulated by an insulating layer made of an inorganic material mainly composed of silicon oxide, and further by firing the molded body, It can be set as the sintered body for magnetic cores of high density and low iron loss.

  The granulated powder of the present invention further comprises a molding resin that retains the molded body after the pressurization and that substantially disappears during the firing. These magnetic powder material, molding resin, and firing resin are provided. It is preferable to be integrated in a granular form.

  According to this configuration, when the magnetic powder material is formed into a molded body, the molded body can be reliably retained.

  In the granulated powder of the present invention, it is mentioned that the molding resin is a thermoplastic resin and the baking resin is a silicone resin.

  According to this configuration, when the magnetic powder material is molded, the molded body is retained by the molding resin, and when fired, the sintered body is sufficiently retained by the binder generated from the firing resin. Can do.

[Molded body]
The molded body of the present invention is characterized in that the granulated powder is pressure-molded.

  According to this configuration, it is possible to obtain a molded body having high density and coarse particles insulated by an insulating layer made of an inorganic material mainly composed of silicon oxide. It can be set as a sintered body.

[Firing body for magnetic core]
The fired body for magnetic core of the present invention is a fired body for magnetic core comprising a magnetic powder material and a binder that integrates the magnetic powder material. This magnetic powder material is composed of a soft magnetic powder including fine particles and coarse particles having different particle diameters, and an insulating material made of an inorganic material mainly composed of silicon oxide formed on the outer peripheral surface of at least the coarse particles of the soft magnetic powder. And having a layer. The binder is an amorphous body containing Si, C, and O.

  According to this structure, it can be set as the high-density sintered body for magnetic cores by using a fine grain and a coarse grain. In addition, the insulating layer made of an inorganic material mainly composed of silicon oxide formed into coarse particles can secure insulation between the coarse particles or between the coarse particles and the fine particles, and can be made into a sintered body for magnetism with low iron loss. . Furthermore, the soft magnetic powder can be reliably retained by an amorphous binder containing Si, C, and O.

  In the fired body for magnetic core of the present invention, the molded body of the present invention is fired.

  According to this configuration, the fired body for magnetic core of the present invention can be easily obtained by firing the molded body of the present invention.

[Method of manufacturing sintered body for magnetic core]
The method for producing a fired body for a magnetic core according to the present invention is a method for producing a fired body for a magnetic core by forming a formed body using soft magnetic powder, and firing the formed body to obtain a fired body. It is characterized by including.
A step of preparing soft magnetic powder containing fine particles and coarse particles having different particle sizes.
A step of forming an insulating layer made of an inorganic material mainly composed of silicon oxide on at least coarse particles of the soft magnetic powder.
The soft magnetic powder including the coarse particles having the insulating layer, the molding resin for retaining the molded body, and the firing resin for retaining the fired body after the firing are mixed and granulated. Process.
A step of compression-molding the granulated powder into a predetermined shape to form a molded body.
A step of firing the molded body to obtain a fired body.

  According to this method, the fired body for magnetic core of the present invention can be easily obtained.

[Electromagnetic parts]
An electromagnetic component according to the present invention includes a magnetic core made of the fired body for a magnetic core according to the present invention, and a coil that is formed by winding a winding and is disposed outside the magnetic core.

  According to this configuration, an electromagnetic component having a magnetic core with a low iron loss and a relatively high magnetic permeability can be obtained.

  According to the magnetic powder material and granulated powder of the present invention, a molded body and a fired body having a high density and a low iron loss can be obtained.

  According to the molded body and fired body of the present invention, high iron loss can be achieved at high density.

  According to the method for producing a fired body of the present invention, a fired body having a high density and a low iron loss can be easily produced.

  According to the electromagnetic component of the present invention, an inductor having a magnetic core with high density and low iron loss can be configured.

  Hereinafter, the magnetic powder material, the granulated powder, the molded body, the fired body, and the electromagnetic component of the present invention will be described in more detail sequentially.

[Magnetic powder material]
<Structure>
The magnetic powder material of the present invention includes soft magnetic powder and an insulating layer made of an inorganic material mainly composed of silicon oxide formed on the outer peripheral surface thereof.

(Soft magnetic powder)
The soft magnetic powder preferably has such a rigidity that it is not substantially deformed by the pressure applied when a molded body to be described later is obtained. For example, a soft magnetic powder having a Vickers hardness HV0.1 of 300 or more is suitable. Specifically, Fe-Si-Al alloys, Fe-Si alloys, Fe-Al alloys, and the like can be given. Of the Fe-Si-Al alloys, those containing 3 to 15% by mass of Si and 1 to 10% by mass of Al are suitable. Among Fe-Si alloys, those containing 3 to 15% by mass of Si are suitable. Of the Fe-Al alloys, those containing 1 to 10% by mass of Al are suitable. With such a soft magnetic powder, it is easy to obtain a fired body having predetermined electromagnetic characteristics. Other uses such as Fe-Ni alloys, Fe-B alloys, Fe-C alloys, Fe-N alloys, Fe-P alloys, Fe-Co alloys, Fe-Ni-Co alloys are also considered. It is done. The Vickers hardness HV0.1 is measured in accordance with JIS-Z2244, and “HV0.1” indicates that the load of the indenter during the test is 0.1 kgf. Specific examples of the Vickers hardness in each alloy system are about 500 for Fe-9.5Si-5.5Al, about 400 for Fe-6.5Si, and about 300 or more for Si-containing alloys of 4 mass% or more.

  In such soft magnetic powder, coarse particles and fine particles are mixed. It is preferable that a plurality of peaks exist in the particle size distribution of these mixed grains. In particular, the coarse particles and the fine particles are preferably a combination in which the particle size distribution ranges do not overlap or a combination in which the distribution ranges are adjacent. By such a combination of coarse particles and fine particles, it is easy to obtain a molded body in which fine particles are filled in the gaps between the coarse particles. For example, the minimum particle size of the coarse particles is preferably about 40 μm, and the maximum particle size is preferably about 150 μm. Use of such coarse grains is effective in suppressing increase in eddy current loss when using a sintered body for a magnetic core in a high frequency range of 1 kHz or higher. The maximum particle size of the fine particles is preferably about 40 μm. However, for the convenience of handling the fine particles, the minimum particle size of the fine particles is preferably 1 μm or more. Further, the particle size ratio between the coarse particles and the fine particles is preferably about the average particle size of the fine particles: the average particle size of the coarse particles = 1: 2 to 1:10. Further, the mass blending ratio of coarse particles to fine particles is preferably about fine particles: coarse particles = 1: 1 to 1: 4. By setting it as such a particle size ratio or compounding ratio, it is easy to obtain a high-density molded body or fired body in which fine particles are filled in gaps between coarse particles.

  In addition, the soft magnetic powder is preferably obtained by the atomization method, but any of those produced by the water atomization method and those produced by the gas atomization method can be used. Since the soft magnetic powder produced by the water atomization method has many irregularities on the particle surface, it is easy to obtain a high-strength fired body by meshing the irregularities. On the other hand, the soft magnetic powder produced by the gas atomization method is preferable because the particle shape is almost spherical, and there are few irregularities that break through the insulating layer. In addition, an insulating coating such as a natural oxide film may be formed on the surface of the soft magnetic powder.

(Insulating layer made of inorganic material mainly composed of silicon oxide)
The insulating layer made of an inorganic material mainly composed of silicon oxide covers the outer peripheral surface of the soft magnetic powder, thereby ensuring insulation between the soft magnetic powders. That is, this insulating layer is not destroyed by the pressing force when the granulated powder using the magnetic powder material is compressed later to form a molded body, and the insulating layer is exposed to the heat when the molded body is fired. Will not be disassembled. The content of silicon oxide in the insulating layer is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more. The silicon oxide is typically SiO ₂ , but at least one of SiO and Si ₂ O ₃ may be contained. Examples of the insulating layer made of an inorganic material mainly composed of silicon oxide include a film formed by heat-treating a silicone resin in an oxygen-containing atmosphere.

  The formation target of the insulating layer made of an inorganic material mainly composed of silicon oxide is at least coarse. When a molded body is formed using the magnetic powder material of the present invention, a state in which fine particles are filled between coarse particles is realized with high frequency. In such a state, suppressing the contact between the coarse particles is effective in reducing the iron loss. Even if there is an insulating layer only in the coarse particles and the fine particles are in direct contact with each other, it can be regarded as a state in which a slightly larger fine particle exists equivalently, and therefore, the effect of reducing the iron loss can be sufficiently achieved. In this way, by forming an insulating layer made of an inorganic material mainly composed of silicon oxide only on coarse particles, high density and low loss can be easily realized. On the other hand, when an insulating layer made of an inorganic material mainly composed of silicon oxide is formed not only on coarse particles but also on fine particles, insulation between soft magnetic powders can be secured more reliably, improving the iron loss reduction effect. Can be made.

  The thickness of the insulating layer made of an inorganic substance mainly composed of silicon oxide is preferably 20 nm or more and 1 μm or less. By setting it as the lower limit value or more, the insulation between the soft magnetic powders is secured, and the mechanical strength that is not broken by the applied pressure during the granulated powder compression is secured. By setting it to the upper limit or less, the thickness of the insulating layer is prevented from being too large, and when the magnetic powder material is formed into a molded body or a fired body, a predetermined density is secured and damage to the insulating layer is suppressed.

<Manufacturing method>
The magnetic powder material of the present invention can be obtained by a production method mainly including classification, resin mixing, and heat treatment.

(Classification)
The soft magnetic powder is classified into coarse particles and fine particles having a predetermined particle size. This classification may be typically performed using a sieve having a predetermined mesh size. For example, the coarse particles may be a mesh having a mesh size corresponding to the upper and lower limits of the particle size. The fine particles may be a mesh having a mesh size corresponding to the upper limit of the particle size. The soft magnetic powder before classification can be classified efficiently by preparing powders having different average particle sizes for coarse particles and fine particles, respectively.

(Mixed resin)
Each of the classified coarse particles and fine particles is mixed with a silicone resin. This mixing is preferably performed with a mixer or the like. The blending amount of the silicone resin is preferably selected according to the specific surface area of the soft magnetic powder to be mixed. By determining the blending amount of the silicone resin according to the specific surface area of the soft magnetic powder, a silicone resin film having a predetermined thickness can be formed on the outer peripheral surface of the soft magnetic powder. The blending amount of the soft magnetic powder and the silicone resin may be, for example, such that the silicone resin is about 0.02 to 1.8% by mass with respect to the mixture of both, more preferably 0.05 to 1.5% by mass, and still more preferably Is 0.1-1.0 mass%. The mixing of soft magnetic powder and silicone resin should be performed separately for both coarse and fine particles, even when forming an insulating layer made of an inorganic material mainly composed of silicon oxide on both coarse and fine particles. Is preferred. When fine particles and coarse particles are mixed together with the silicone resin, the fine silicone resin coating becomes relatively thick or the fine particles are aggregated together, but the coarse particles and fine particles are separated and mixed with the silicone resin. These inconveniences can be suppressed. Further, the silicone resin may be adjusted to a slurry having an appropriate viscosity with an appropriate solvent and mixed with the soft magnetic powder.

(Curing (dry))
The silicone resin film formed on the outer peripheral surface of the soft magnetic powder is preferably cured by heating. This resin is preferably cured by heating after mixing the soft magnetic powder and the silicone resin without heating. By curing the silicone resin, it is possible to prevent the silicone resins from being bonded to each other during the heat treatment described later. The curing condition is preferably about 100 ° C. to 200 ° C. × 30 to 120 minutes, for example.

(Hoshigushi)
Usually, since the soft magnetic powders after curing of the silicone resin are partly joined to each other through the silicone resin, it is preferable to perform “unraveling” to separate the joints. The loosening operation is enough to lightly screen the soft magnetic powder after curing the silicone resin.

(Heat treatment)
By this heat treatment, the silicone resin film formed on the surface of the soft magnetic powder is used as an insulating layer made of an inorganic material mainly composed of silicon oxide. Although the silicone resin decomposes at about 300 ° C., the silicone resin can be reliably converted to silicon oxide by setting the temperature higher. In particular, by increasing the temperature, the crystallinity of silicon oxide can be increased, and an insulating layer having a high hardness can be formed. A preferable heat treatment temperature is 400 ° C to 1000 ° C, and a more preferable heat treatment temperature is 500 ° C to 800 ° C. A preferable heat treatment time is about 30 minutes to 2 hours. By this heat treatment, the silicone resin film becomes an insulating layer made of an inorganic material mainly composed of silicon oxide having a thickness of about half.

(Disintegration)
Usually, a magnetic powder material on which an insulating layer made of an inorganic material mainly composed of silicon oxide is formed has a portion where the insulating layers of particles are bonded to each other. Therefore, it is preferable to crush the magnetic powder materials bonded in this way by an appropriate means.

[Granulated powder]
<Structure>
The magnetic powder material is further mixed with a molding resin and a firing resin to form a granulated powder. In this granulated powder, at least a firing resin and a magnetic powder material are integrated, and if necessary, a molding resin may be further integrated.

(Resin for molding)
When the magnetic powder material is compressed into a molded body, the molding resin is a resin for retaining the molded body, and is preferably a thermoplastic resin. In the case of granulated powder, since the firing resin described below is integrated with the magnetic powder material, if the shaped body can be retained with this firing resin, the addition of the molding resin can be omitted. Also good. As specific examples of the thermoplastic resin, it is considered that polyvinyl alcohol, acrylic resin, polyethylene resin and the like can be used in addition to polyvinyl butyral.

(Resin for baking)
When the fired resin is made by firing a compact obtained by compressing the magnetic powder material, the firing resin becomes a ceramic compound and becomes a binder for holding the magnetic powder material. Typically, a silicone resin is used as the firing resin. As will be described later, this silicone resin is presumed to be an amorphous binder containing Si, C, and O during the firing process. In addition, a sodium silicate binder (water glass) can be used as the firing resin.

<Manufacturing method>
The granulated powder is produced by mixing a magnetic powder material, a firing resin and, if necessary, a molding resin with a mixer or the like. This mixing usually forms unit particles of granulated powder in which several magnetic powder materials are integrated with a firing resin (molding resin). The molding resin or the firing resin may be adjusted to a slurry having an appropriate viscosity with an appropriate solvent and mixed with the magnetic powder material.

  The mixture of magnetic powder material and firing resin (when adding molding resin, the total mixture of magnetic powder material, firing resin and molded body resin) is 5-15% by volume of the total amount of resin added. It is preferable to mix so that it becomes. By setting the resin content above this lower limit, the molded body or fired body can be sufficiently retained, and conversely by setting it to the upper limit or lower, the amount of resin in the mixture becomes an appropriate amount, and the molded body or fired body. Can be densified.

[Molded body]
<Structure>
The molded body of the present invention is obtained by pressure-molding the granulated powder into a predetermined shape. That is, in this molded body, the magnetic powder material is integrated with the firing resin and, if necessary, the molding resin. Since the soft magnetic powder used here is not substantially deformed by the pressure at the time of molding, damage to the high-hardness insulating layer formed on the outer periphery of the soft magnetic powder is also suppressed. What is necessary is just to select the shape of a molded object according to the shape of the magnetic core of electromagnetic components.

<Manufacturing method>
Such a molded body is obtained by a method including a step of supplying granulated powder to a mold and a step of pressing the granulated powder in the mold to form a molded body.

  Here, the pressure for pressurizing the granulated powder is preferably about 500 MPa to 1200 MPa. By setting the lower limit value or more, a high-density molded body can be obtained. Moreover, the damage of an insulating layer accompanying the deformation | transformation of a soft magnetic powder can be suppressed by setting it as an upper limit or less. This pressurization may be performed at room temperature, but when a thermoplastic resin is used as the molding resin, it is preferably molded at a temperature equal to or higher than the glass transition temperature of the resin. This can improve the density and strength of the molded body.

[Fired body]
<Structure>
The sintered body for a magnetic core of the present invention includes the above-described magnetic powder material and a binder that integrates the magnetic powder material.

  As described above, the magnetic powder material is a granular material in which an insulating layer made of an inorganic material mainly composed of silicon oxide is formed on the outer peripheral surface of the soft magnetic powder. This insulating layer remains almost intact even after firing, and ensures insulation between the soft magnetic powders.

  On the other hand, the binder is a ceramic material in which the firing resin is modified by heat during firing. In this binder, it is presumed that the silicone resin added as a firing resin is an amorphous body containing Si, C, and O during the firing process. In other words, it is a fired body in which the magnetic powder material is held in the binder, and the vicinity of the outer periphery of the soft magnetic powder is composed of an insulating layer made of an inorganic material mainly composed of silicon oxide. The outside of the insulating layer is an amorphous material containing a material having a higher C content than the insulating layer, that is, Si, C, and O.

<Manufacturing method>
Such a fired body can be obtained by subjecting the above-described molded body to a predetermined heat treatment. The heating temperature for this heat treatment is preferably 600 ° C to 1000 ° C. The heating time is preferably about 30 minutes to 2 hours. Many strains are introduced into the soft magnetic powder constituting the green body before firing. By heat-treating the molded body under the above conditions, the strain can be sufficiently removed. Furthermore, by performing heat treatment under the above conditions, the molding resin disappears, and the firing resin is used as an amorphous binder containing Si, C, and O. In addition, the heat treatment atmosphere is preferably an inert gas atmosphere such as a nitrogen atmosphere or a reduced pressure atmosphere. Heat treatment in such an atmosphere is preferable in that the mass of the firing resin can be prevented from being reduced and the fired body can be reliably retained.

[Electromagnetic parts]
The electromagnetic component of the present invention includes a magnetic core and a coil. A magnetic core consists of the sintered body for magnetic cores mentioned above. Examples of the shape of the magnetic core include an E-type and an I-type core such as an annular shape and a rod shape. On the other hand, the coil is formed by winding a winding having a conductive wire provided with an insulating coating. As the cross-sectional shape of the winding, various shapes such as a circle and a rectangle can be used. For example, a round wire may be wound in a spiral shape to form a cylindrical coil, or a flat wire may be wound edgewise in a spiral shape to form a rectangular tube coil.

  This electromagnetic component may be configured by winding a winding around the outer periphery of the magnetic core, or may be configured by fitting an air-core coil formed in advance in a spiral shape into the outer periphery of the magnetic core.

  Specific examples of the electromagnetic component include a high frequency choke coil, a high frequency tuning coil, a bar antenna coil, a power choke coil, a power transformer, a switching power transformer, and a reactor.

  Under the following conditions, the magnetic powder material was produced, the granulated powder was produced, the molded body was molded, and the fired body was fired to produce a test piece of the sintered body for the magnetic core, and several characteristics of the test piece were evaluated. .

<Preparation of sample>
First, two types of soft magnetic powders having a composition of Fe-9.5 mass% Si-5.5 mass% Al and obtained by a gas atomization method and having an average particle diameter of 30 μm and 75 μm are prepared. The Vickers hardness HV0.1 of the alloy having this composition is 500. Each soft magnetic powder was sieved and classified into two types: fine particles having a maximum particle size of 38 μm or less and coarse particles having a minimum particle size of 45 μm and a maximum particle size of 106 μm. The average particle size of the fine particles is about 25 μm, the average particle size of the coarse particles is about 75 μm, and the ratio of these average particle sizes is 1: 3.

  Next, the coarse particles are mixed with a silicone resin by a mixer to form a silicone resin film on the surface of the coarse particles. The blending amount of the soft magnetic powder and the silicone resin is such that the silicone resin is 0.3% by mass with respect to the mixture of both. Further, fine particles having a silicone resin film formed thereon are also prepared. The silicone resin used is a resin-based silicone oligomer containing 40% alkoxy groups as reactive groups. Its viscosity at 25 ° C. is 4.9 mPa · s, and its specific gravity is 1.09. The thickness of the silicone resin film is about 250 nm.

  Subsequently, the soft magnetic powder on which the silicone resin film is formed is subjected to a heat treatment at 180 ° C. for 1 hour in an air atmosphere to cure the resin. At this point, the silicone resin has not been converted to silicon oxide. Thereafter, the obtained soft magnetic powder with a silicone resin coating is sieved to loosen the particles.

  Next, the obtained soft magnetic powder with a silicone resin coating is subjected to a heat treatment at 600 ° C. for 1 hour in an air atmosphere to form the silicone resin coating as an insulating layer made of an inorganic material mainly composed of silicon oxide. The thickness of the insulating layer is about 120 nm. When a soft magnetic powder with an insulating layer is obtained, pulverization is performed to separate the particles from each other.

  According to the above process, a total of four types of magnetic powder materials including coarse particles without an insulating layer mainly composed of silicon oxide, coarse particles without an insulating layer, coarse particles with an insulating layer, fine particles without an insulating layer, and fine particles with an insulating layer are obtained. Produced.

The obtained coarse particles and fine particles are combined, and a molding resin and a firing resin are mixed to produce granulated powder that becomes a fired body of the following samples No. 1 to No. 3. The blending ratio of coarse particles and fine particles in the granulated powder is 7: 3 by mass ratio. In any case, the total addition amount of the molding resin and the firing resin is 10% by volume of the total raw material of the granulated powder. Polyvinyl butyral (Denka Butyral # 3000-K manufactured by Denki Kagaku Kogyo Co., Ltd.) was used as the molding resin, and silicone resin was used as the firing resin. This silicone resin is different from the silicone resin used for the insulation coating, and is a silicone varnish mainly composed of polyalkylsiloxane, and after firing, is an amorphous body containing Si, C, and O It is estimated to be. Its viscosity at 25 ° C. is 100 mPa · s, and its specific gravity is 1.02.
(Invention) Sample No.1: Coarse grain: with insulation treatment, Fine grain: No insulation treatment (Invention product) Sample No.2: Coarse grain: With insulation treatment, Fine grain: With insulation treatment (Comparative product) Sample No.3 : Coarse grain: no insulation treatment, fine grain: no insulation treatment

  Next, the granulated powder of each sample is supplied to a mold and compressed to form a molded body. The surface pressure during this pressure molding is 980 MPa. With this surface pressure, the soft magnetic powder is not substantially deformed during molding.

  Then, the obtained molded body is heat-treated at 800 ° C. for 1 hour in a nitrogen atmosphere to obtain a fired body. The obtained test piece made of the fired body has a ring shape and has an outer diameter of 34 mm, an inner diameter of 20 mm, and a thickness of 5 mm.

<Evaluation>
About each sample produced as mentioned above, the characteristic value enumerated below was measured and the calcination object was evaluated. The evaluation results are listed in Tables 1 and 2 below. Underlined sample numbers in each table indicate comparative products.

≪Magnetic characteristics≫
Winding was applied to the ring-shaped test piece to prepare a measuring member for measuring the magnetic properties of the test piece. About this test piece, BH / μ analyzer SY-8258 made by Iwatsu Measurement Co., Ltd., excitation magnetic flux density Bm: 1kG (= 0.1T), measurement frequency: 100kHz, iron loss W1 / 100k and AC initial permeability μiac Was measured. Further, the frequency curve of iron loss was fitted by the following three equations by the least square method, and the hysteresis loss coefficient Kh (kWs / m ³ ) and eddy current loss coefficient Ke (kWs ² / m ³ ) were calculated.
(Iron loss) = (Hysteresis loss) + (Eddy current loss)
(Hysteresis loss) = (Hysteresis loss coefficient) x (Frequency)
(Eddy current loss) = (Eddy current loss coefficient) × (Frequency) ²

≪Density≫
The outer diameter, inner diameter, thickness, and weight of each test piece were measured, and the density (g / cm ³ ) of the test piece was calculated. The outer diameter, inner diameter, and thickness were measured using a micrometer.

≪Evaluation results≫
From the results in Tables 1 and 2, sample Nos. 1 and 2 are compared to sample No. 3 because insulation between soft magnetic powders is ensured reliably by an inorganic insulating layer mainly composed of silicon oxide. Therefore, the eddy current loss coefficient Ke is small and the iron loss is also kept low. On the other hand, sample No. 1 using a magnetic powder material having an insulating layer only in coarse grains has a slightly higher iron loss than sample No. 2 having an insulating layer in both coarse grains and fine grains. Is high.

A soft magnetic powder having the same composition, production method, and particle size as in Example 1 was formed by forming an insulating layer made of an inorganic material mainly composed of silicon oxide on the surface by the same method as in Example 1. Only fine particles and only coarse particles Prepare a powder. Granulation that becomes a fired body of sample No. 4 (uses only fine particles) and No. 5 (uses only coarse particles) by mixing molding resin and firing resin for each of coarse and fine particles. Make flour. The amount of resin and the type of resin are the same as in Example 1.
(Comparative product) Sample No.4: Use only fine particles (38μm or less), with insulation treatment (Comparative product) Sample No.5: Use only coarse particles (45-106μm), with insulation treatment

  Subsequently, the granulated powder was fired in the same manner as in Example 1 and evaluated. The evaluation results are listed in Tables 1 and 2 below. From the results of Tables 1 and 2, the samples No. 4 and No. 5 using only fine particles and only coarse particles have a lower density than samples No. 1 to No. 3 using a combination of fine particles and coarse particles. Low initial permeability.

Two types of powders having the same composition and production method as those of Example 1 and having an average particle diameter of 30 μm and 75 μm are prepared. Each soft magnetic powder was sieved and classified into two types: fine particles having a maximum particle size of 38 μm or less and coarse particles having a minimum particle size of 45 μm and a maximum particle size of 180 μm. The average particle size of the fine particles is about 25 μm, and the average particle size of the coarse particles is about 90 μm. Next, an insulating layer made of an inorganic material mainly composed of silicon oxide is formed on the surface of the coarse particles by the same method as in Example 1. The obtained coarse particles and fine particles are combined and a molding resin and a firing resin are mixed to produce a granulated powder that becomes a fired body of Sample No. 6 below. The blending ratio of coarse particles and fine particles in the granulated powder, the amount of resin, and the type of resin are the same as in Example 1.
(Invention) Sample No.6: Coarse grain: 45-180μm, with insulation treatment
Fine: 38μm or less, no insulation treatment

  Subsequently, the granulated powder was fired in the same manner as in Example 1 and evaluated. The evaluation results are listed in Tables 1 and 2 below. From the results of Tables 1 and 2, sample No. 6 has a powder with a large particle size, and the generated intragranular eddy loss is large. Therefore, eddy current loss coefficient Ke is larger than sample No. 1, and iron loss is large.

A soft magnetic powder having the same composition, production method, and particle size as in Example 1 is prepared. Next, the coarse particles are mixed with a silicone resin by a mixer to form a silicone resin film on the surface of the coarse particles. The blending amount of the soft magnetic powder and the silicone resin is set so that the silicone resin is 0.02 to 1.8% by mass with respect to the mixture of both. The silicone resin film is converted to an insulating layer made of an inorganic material mainly composed of silicon oxide by the same method as in Example 1. The obtained coarse particles and fine particles are combined and a molding resin and a firing resin are mixed to produce granulated powder that becomes a fired body of the following samples No. 7 to No. 10. The blending ratio of coarse particles and fine particles in the granulated powder, the amount of resin, and the type of resin are the same as in Example 1.
(Invention product) Sample No.7: Coarse particles: Covering amount = 0.02 mass%, Fine particles: No insulation treatment (Invention product) Sample No.8: Coarse particles: Coating amount = 0.1 mass%, Fine particles: No insulation treatment (Invention) Product) Sample No. 9: Coarse particles: coating amount = 1.0 mass%, fine particles: no insulation treatment (Invention product) Sample No. 10: Coarse particles: coating amount = 1.8 mass%, fine particles: no insulation treatment

  Subsequently, the granulated powder was fired in the same manner as in Example 1 and evaluated. The evaluation results are listed in Tables 1 and 2 below. From the results of Tables 1 and 2, Sample Nos. 7 to 10 subjected to insulation treatment have a smaller eddy current loss coefficient Ke and a lower iron loss than Sample No. 3. Sample No. 7 with a small amount of coating has a slightly large iron loss, and sample No. 10 with a large amount of coating has a low density and a slightly low initial permeability.

A soft magnetic powder having the same composition, production method, and particle size as in Example 1 is prepared, and a silicone resin film is formed on the surface of the coarse particles by the same method as in Example 1. Next, the obtained soft magnetic powder with a silicone resin coating is subjected to heat treatment at 200 ° C. for 1 hour. The obtained coarse particles and fine particles are combined and a molding resin and a firing resin are mixed to produce a granulated powder that becomes a fired body of Sample No. 11 below. The blending ratio of coarse particles and fine particles in the granulated powder, the amount of resin, and the type of resin are the same as in Example 1.
(Comparative product) Sample No. 11: Coarse grain: Heat treatment temperature = 200 ° C, Fine grain: No insulation treatment

  Subsequently, the granulated powder was fired in the same manner as in Example 1 and evaluated. The evaluation results are listed in Tables 1 and 2 below. From the results of Tables 1 and 2, sample No. 11 has a lower heat treatment temperature and incomplete conversion of the silicone resin coating to silicon oxide and insufficient insulation between the powders compared to sample No. 1. The eddy current loss coefficient Ke is large, and the iron loss is also large.

By comparing the evaluation results of the above samples No.1~11 Overall, the invention products, the eddy current loss coefficient ^{(× 10 -8 kWs 2 / m} 3): 4.5 or less, the core loss (kW / m ³⁾ : 650 or less, density (g / cm ³ ): 5.5 or more, AC initial permeability μiac (H / m): 70 or more, and it can be seen that high density, high permeability, and low iron loss are well-balanced. In particular, sample Nos. 1, ^{2, 8} , and 9 have an eddy current loss coefficient (× 10 ⁻⁸ kWs ² / m ³ ): 3.5 or less, iron loss (kW / m ³ ): 600 or less, density (g / cm) ³ ): 5.7 or higher, AC initial permeability μiac (H / m): 90 or higher.

  In addition, this invention is not necessarily limited to the Example mentioned above, In the range which does not deviate from the summary of this invention, it can change suitably.

  The magnetic powder material, granulated powder, magnetic core molded body, and core core fired body manufacturing method of the present invention are suitable for obtaining the core fired body used in various inductors. The sintered body for magnetic core and electromagnetic component of the present invention can be suitably used for a high-frequency choke coil, a high-frequency tuning coil, a bar antenna coil, a power choke coil, a power transformer, a switching power transformer, a reactor, and the like.

Claims (13)

Soft magnetic powder containing fine particles and coarse particles having different particle sizes;
A magnetic powder material comprising: an insulating layer made of an inorganic substance mainly composed of silicon oxide formed on at least a coarse outer peripheral surface of the soft magnetic powder.   The magnetic powder material according to claim 1, further comprising an insulating layer made of an inorganic material mainly composed of silicon oxide only on the coarse particles.   The magnetic powder material according to claim 1, wherein the soft magnetic powder is at least one of a Fe—Si—Al alloy, a Fe—Si alloy, and a Fe—Al alloy. The fine particles have a maximum particle size of less than 40 μm,
The magnetic powder material according to claim 1, wherein the coarse particles have a minimum particle size of 40 μm or more and a maximum particle size of 150 μm or less.   The magnetic powder material according to any one of claims 1 to 4, wherein a constituent material of the soft magnetic powder has a Vickers hardness HV0.1 of 300 or more. It is a granulated powder that is made into a molded body by pressing, and is made into a sintered body for a magnetic core by firing the molded body,
Magnetic powder material according to any one of claims 1 to 5,
A firing resin that becomes a binder during the firing and retains the fired body after firing,
A granulated powder comprising the magnetic powder material and a firing resin integrated in a granular form. Furthermore, while holding the shaped body after the pressurization, comprising a molding resin that substantially disappears during the firing,
The granulated powder according to claim 6, wherein the magnetic powder material, the molding resin, and the firing resin are integrated in a granular form. The molding resin is a thermoplastic resin;
The granulated powder according to claim 7, wherein the baking resin is a silicone resin.   A molded body obtained by pressure-molding the granulated powder according to any one of claims 6 to 8. A sintered body for a magnetic core comprising a magnetic powder material and a binder for integrating the magnetic powder material,
The magnetic powder material is
Soft magnetic powder containing fine particles and coarse particles having different particle sizes;
Of this soft magnetic powder, it has an insulating layer made of an inorganic material mainly composed of silicon oxide formed on at least the outer peripheral surface of coarse particles,
The sintered body for a magnetic core, wherein the binder is an amorphous body containing Si, C, and O.   The fired body for a magnetic core according to claim 10, wherein the molded body according to claim 9 is fired. A method for producing a fired body for a magnetic core by forming a molded body using soft magnetic powder and firing the molded body to obtain a fired body,
Preparing a soft magnetic powder containing fine particles and coarse particles having different particle sizes;
A step of forming an insulating layer made of an inorganic material mainly composed of silicon oxide in at least coarse particles of the soft magnetic powder;
The soft magnetic powder including the coarse particles having the insulating layer, the molding resin for retaining the molded body, and the firing resin for retaining the fired body after the firing are mixed and granulated. Process,
A step of compression molding the granulated powder into a predetermined shape to form a molded body;
A method for producing a fired body for a magnetic core, comprising a step of firing the formed body to obtain a fired body. A magnetic core comprising the sintered body for a magnetic core according to claim 10;
An electromagnetic component comprising a coil wound around and disposed outside the magnetic core.