JP7104905B2 - MAGNETIC CORE, MANUFACTURING METHOD THEREOF, AND COIL COMPONENTS - Google Patents

Description

The present invention relates to a magnetic core, its manufacturing method, and coil parts, and more particularly to a magnetic core using alloy-based magnetic powder, its manufacturing method, and coil parts such as reactors and inductors using this magnetic core. .

Magnetic powders, especially magnetic powders of amorphous alloys with excellent soft magnetic properties, have good magnetic properties such as relative permeability and saturation magnetic flux density, and are suitable for use in high-frequency regions. It is actively researched and developed.

A magnetic core using this magnetic powder is obtained by pressure-molding a composite material containing magnetic powder and a binder. Such distortion may lead to an increase in magnetic loss. For this reason, conventionally, heat treatment is performed at a high temperature after pressure molding to remove distortion. Also, as a binder, a silicone resin with good heat resistance is widely used, which can suppress deterioration of insulation even when heat treatment is performed at a high temperature.

However, magnetic powders of amorphous alloys are difficult to be plastically deformed, so that the packing density during pressure molding is low, which may lead to a decrease in relative magnetic permeability.

Therefore, for example, Patent Document 1 discloses a magnetic core (powder magnetic core) obtained by pressure molding a composite material (mixed powder) containing a soft magnetic alloy powder and a plurality of binders, wherein the plurality of binders at least two binders are incompatible with each other, one of the mutually incompatible binders is a thermosetting silicone resin and the other is a thermosetting phenolic resin, and the soft magnetic alloy A magnetic core has been proposed in which a powder particle surface has regions in which the component ratios of the plurality of binders are different.

In Patent Document 1, a silicone resin and a phenolic resin, which are incompatible with each other, are used as binders, and these bonds are formed on the particle surface of the soft magnetic alloy powder so that a silicone resin-rich region and a phenolic resin-rich region are formed. coated with an agent. That is, in Patent Document 1, the particle surfaces of the magnetic powder are in contact with the binder so that the mutually incompatible silicone resin and phenol resin are mixed. And while ensuring insulation in the region with a large amount of silicone resin, in the region with a large amount of phenol resin, by increasing the fluidity of the soft magnetic alloy powder during pressure molding and improving the filling density of the soft magnetic alloy powder, We are trying to obtain a magnetic core with high insulation resistance and high relative magnetic permeability.

Japanese Patent No. 6359273 (claim 1, paragraphs [0002] to [0006], [0016], [0017], [0021], etc.)

However, in Patent Document 1, since the phenol resin is inferior in insulating properties to the silicone resin, current tends to leak from the particle surface in contact with the phenol resin, resulting in increased eddy current loss and an increase in magnetic loss. may invite.

On the other hand, since silicone resin has a lower hardness than phenolic resin, although the surface of the particles in contact with silicone resin has good insulation properties, sufficient mechanical strength cannot be ensured, and a large external force can be applied. It may be easily damaged if

The present invention has been made in view of such circumstances, and provides a magnetic core having good insulation, low magnetic loss, and sufficient mechanical strength, a method for manufacturing the same, and the magnetic core. To provide a coil component such as a reactor using

The present inventors have made intensive studies to achieve the above object, and have found that the entire magnetic powder is coated with a predetermined amount of a first binder containing silicone resin as a main component, and By bonding the first binders together with a predetermined amount of the second binder such as a phenolic resin having a high hardness, good insulation, low magnetic loss, and sufficient mechanical strength are ensured. The inventors have found that a magnetic core can be obtained.

The present invention has been made based on such findings, and the magnetic core according to the present invention is a magnetic core made of a composite material containing magnetic powder and a binder, wherein the binder is , a first binder containing a silicone resin as a main component, and a second binder consisting of at least one resin having a hardness higher than that of the first binder, and the first binder The content of the agent is 0.25 to 1 wt%, the content of the second binder is 0.25 to 1 wt%, and the total content of the first and second binders is is 1 to 1.75 wt%, the magnetic powder is coated with the first binder, and the first binders are bonded to each other through the second binder. is characterized by

As a result, the magnetic powder is coated with the first binder mainly composed of silicone, which has good insulating properties, so that leakage of electric current from the magnetic powder can be suppressed, and an increase in eddy current loss can be suppressed. This makes it possible to keep the magnetic loss low. In addition, since the magnetic powder coated with the first binder is bonded to each other through the second binder having a hardness higher than that of the first binder, the second binder having a higher hardness can The mechanical strength is improved, and breakage can be suppressed even when a large external force is applied.

As described above, the present invention can provide a magnetic core having both low magnetic loss and mechanical strength.

Also, in the magnetic core of the present invention, the second binder preferably contains at least one of phenol resin and polyimide resin.

Further, in the magnetic core of the present invention, the silicone resin is preferably methylphenyl-based.

That is, since the methylphenyl-based silicone resin has a small shrinkage rate during molding, it can suppress the occurrence of distortion in the magnetic powder during molding, and suppresses the increase in hysteresis loss without requiring heat treatment at high temperatures. can contribute to the reduction of the magnetic loss of the magnetic core.

Further, in the magnetic core of the present invention, the content of the first binder is more preferably 0.5 wt% or more, and the content of the second binder is 0.5 wt% or more. is more preferred. As a result, good mechanical strength and insulation can be secured, and a good magnetic core with low magnetic loss can be obtained.

Further, in the magnetic core of the present invention, it is preferable that a film made of an insulating material is formed on the surface of the magnetic powder. Thereby, further improvement in insulation can be achieved.

Further, in the magnetic core of the present invention, it is preferable that the magnetic powder contains Fe as a main component, and that an amorphous phase and a nanocrystalline phase are mixed.

As a result, it is possible to obtain a magnetic core having good soft magnetic properties, low magnetic loss, good mechanical strength, good magnetic properties such as relative permeability and magnetic flux saturation density, and good DC superimposition properties.

Further, in the magnetic core of the present invention, the magnetic powder preferably has an average particle size of 30 to 80 μm in equivalent circle diameter.

Here, the average particle diameter means the cumulative 50% particle diameter _D50 (median diameter).

Further, a method for manufacturing a magnetic core core according to the present invention includes a step of producing a magnetic powder, mixing the magnetic powder with a first binder containing a silicone resin as a main component, and mixing the magnetic powder with the above-mentioned a step of coating with a first binder; and a second binder comprising the magnetic powder coated with the first binder and at least one resin having higher hardness than the first binder. and bonding the first binders to each other through the second binder to produce a composite material containing the magnetic powder and the first and second binders; and pressing the composite material to produce a magnetic core , wherein the step of producing the composite material includes: and adding the first binder to the magnetic powder so that the content of the first binder in the composite material is 0.25 to 1.0 wt%, and the magnetic coating the body powder with the first binder; and a step of adding the first binder to the magnetic powder coated with one binder and bonding the first binders to each other via the second binder .

Thereby, a magnetic core having low magnetic loss and good mechanical strength can be efficiently manufactured.

Further, in the magnetic core manufacturing method of the present invention, it is preferable that the second binder contains at least one of phenol resin and polyimide resin.

Further, the method for manufacturing a magnetic core of the present invention preferably includes the step of applying an insulating material to the surface of the magnetic powder to form an insulating film.

This makes it possible to efficiently produce a magnetic core with even better insulation.

Further, in the magnetic core manufacturing method of the present invention, the step of producing the magnetic powder includes weighing and blending a predetermined raw material containing at least an Fe component, and heating the blended mixture. A step of producing a melt, a step of ejecting the melt onto a rotating body and rapidly cooling and solidifying to produce a metal ribbon, and heat-treating the metal ribbon to precipitate nanocrystals in an amorphous phase. It is preferable to include a step of producing a nano-crystallized ribbon containing Fe as a main component, and a step of pulverizing the nano-crystallized ribbon to produce the magnetic powder.

By heat-treating the metal ribbon produced by the single-roll quenching method and pulverizing it, it is possible to obtain high-quality nanocrystalline magnetic powder with good soft magnetic properties with high efficiency.

According to another aspect of the present invention, there is provided a coil component including any one of the above magnetic cores and a coil conductor.

Further, in the coil component of the present invention, it is preferable that the coil conductor is wound around the magnetic core.

According to the magnetic core of the present invention, the magnetic core is formed of a composite material containing magnetic powder and a binder, wherein the binder is a first binder containing a silicone resin as a main component; and a second binder made of at least one resin having a hardness higher than that of the first binder, and the content of the first binder is 0.25 to 1 wt%, and the The second binder has a content of 0.25 to 1 wt%, the total content of the first and second binders is 1 to 1.75 wt%, and the magnetic powder contains Since the magnetic powder is coated with the first binder and the first binders are bonded to each other via the second binder, the magnetic powder contains silicone having good insulating properties as a main component. Since the magnetic powder is coated with the first binder, leakage of electric current from the magnetic powder can be suppressed, eddy current loss can be suppressed from increasing, and magnetic loss can be suppressed to a low level. In addition, since the magnetic powder coated with the first binder is bonded to each other through the second binder having a hardness higher than that of the first binder, the second binder having a higher hardness can Mechanical strength is improved, and breakage can be suppressed even when an external force is applied. As described above, the present invention can provide a magnetic core having both low magnetic loss and mechanical strength.

Further, according to the magnetic core core manufacturing method of the present invention, the step of producing the magnetic powder, mixing the magnetic powder with the first binder containing a silicone resin as a main component, and mixing the magnetic powder a step of coating with the first binder; and a second bond comprising the magnetic powder coated with the first binder and at least one resin having higher hardness than the first binder. a step of mixing the magnetic powder and the first and second binders, bonding the first binders to each other through the second binder, and producing a composite material containing the magnetic powder and the first and second binders. and press-molding the composite material to produce a magnetic core , wherein the step of producing the composite material includes a total content of the first and second binders of 1 to 1.75 wt. % range, and the first binder is added to the magnetic powder so that the content of the first binder in the composite material is 0.25 to 1.0 wt%, and the a step of coating the magnetic powder with the first binder; and a step of adding to the magnetic powder coated with the first binder and bonding the first binders to each other through the second binder, so that the magnetic powder has low magnetic loss and good mechanical properties. A magnetic core having strength can be efficiently manufactured.

Further, according to the coil component of the present invention, since it includes the magnetic core and the coil conductor according to any one of the above, the reactor has low magnetic loss and good mechanical strength and is suitable for use in a high frequency region. etc. can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows one Embodiment of the particle shape of the magnetic substance powder used for the magnetic core which concerns on this invention, (a) is a cross-sectional view, (b) is a longitudinal cross-sectional view. 1 is a perspective view showing an embodiment (first embodiment) of a magnetic core according to the present invention; FIG. FIG. 3 is a vertical cross-sectional view showing details of a main part of the magnetic core. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic process drawing which shows one embodiment of the manufacturing method of the metal ribbon used for this invention. 1 is a perspective view showing an embodiment of a reactor as a coil component according to the present invention; FIG. FIG. 6 is a vertical cross-sectional view showing details of a main part of a magnetic core according to a second embodiment of the present invention; FIG. 10 is a vertical cross-sectional view showing details of a main part of a magnetic core according to a third embodiment of the present invention; It is a figure which shows the relationship between content of a silicone resin and powder resistance in a present Example. FIG. 4 is a diagram showing the relationship between the content of silicone resin and core loss in the present example. FIG. 3 is a diagram showing the relationship between the content of silicone resin and radial crushing strength in the present example. It is a figure which shows the relationship between content of a phenol resin and powder resistance in a present Example. FIG. 4 is a diagram showing the relationship between the content of phenolic resin and core loss in this example. It is a figure which shows the relationship between content of a phenol resin and radial crushing strength in a present Example.

Next, embodiments of the present invention will be described in detail.

FIG. 1 is a diagram showing an embodiment of the particle shape of magnetic powder used in a magnetic core according to the present invention, where (a) is a cross-sectional view and (b) is a longitudinal cross-sectional view.

In the magnetic powder shown in FIG. 1, for convenience of explanation, the cross-sectional shape is circular, and the vertical cross-sectional shape is a constant thickness with four rounded corners 1a. It has a substantially circular or substantially elliptical shape, the outer circumference has fine irregularities, and the vertical cross-sectional shape has unevenness in thickness. Therefore, in FIG. 1, the average length a in the radial direction and the average thickness b in the thickness direction indicate the arithmetic average of the length and thickness, respectively.

The magnetic powder 1 is three-dimensionally formed into a flat spherical shape, and has an aspect ratio a/b, which indicates the ratio of the average length a to the average thickness b, of 1.8 to 6.8. A portion 1a is formed into a curved surface having a radius R of 0.8 to 25 μm.

By using this magnetic powder 1, it is possible to realize a magnetic core with good DC superimposition characteristics and low magnetic loss. That is, the present magnetic core is produced using magnetic powder made of pulverized metal ribbons, as will be described later. It has a sharp shape. Therefore, if the molding process is performed while the edges of the magnetic powder are in contact with each other, the magnetic flux will concentrate on the edges, which may deteriorate the DC superimposition characteristics. Therefore, in order to avoid concentration of the magnetic flux on the edge portion, it is preferable to form the magnetic powder 1 into a spherical shape, and it is particularly preferable to form the corner portion 1a into a curved surface.

On the other hand, when an external force is applied to the metal ribbon and mechanical processing including pulverization is performed for a long time, spheroidization progresses, but the magnetic powder may be greatly distorted. Such distortion cannot be easily removed even if heat treatment is performed at a high temperature after machining. Due to this distortion, the coercive force Hc of the magnetic powder 1 increases, resulting in an increase in hysteresis loss. Therefore, the magnetic loss increases.

Therefore, in the present embodiment, the aspect ratio a/b of the magnetic powder 1 and the radius R of the corner 1a are defined as described above. The reason for this will be detailed below.

(a) aspect ratio a/b
As described above, when the magnetic powder 1 has a nearly spherical shape, unlike the magnetic powder having distorted and sharp edges, the magnetic flux flows while diffusing on the spherical surface, so that the concentration of the magnetic flux can be suppressed. It is possible to improve the DC superimposition characteristics. For that purpose, the aspect ratio a/b must be 6.8 or less. That is, when the aspect ratio a/b exceeds 6.8, the average length a in the radial direction becomes relatively large, and the average thickness b in the thickness direction becomes relatively small. A flat shape is obtained, and the radius R of the corner portion 1a becomes small, so that the curved surface property of the corner portion 1a is impaired. Therefore, when a DC bias current is applied to the coil component, the magnetic flux concentrates on the corner portion 1a, which may reduce the inductance and cause deterioration of the DC superimposition characteristics. Furthermore, since the corner 1a has a sharp shape, even if it is attempted to coat the magnetic powder 1 with a binder as described later, it becomes difficult to uniformly coat the magnetic powder 1 with the binder, resulting in insufficient insulation. may occur, resulting in an increase in magnetic loss.

On the other hand, when the aspect ratio a/b is spheroidized to less than 1.8, external force is applied to the metal ribbon for a long period of time, and large strain is likely to be formed in the magnetic powder 1 after processing. As a result, the coercive force Hc increases, the hysteresis loss increases, and the magnetic loss also increases in this case.

Therefore, in the present embodiment, the aspect ratio a/b is set to 1.8 to 6.8.

(b) Radius R of corner 1a
The radius R of the corner portion 1a is also an important factor in order to avoid the occurrence of magnetic flux concentration while ensuring low magnetic loss. That is, when the radius R of the corner portion 1a is less than 0.8 μm, the curvature of the corner portion 1a is impaired, so the magnetic flux tends to concentrate on the corner portion 1a, resulting in a decrease in inductance and a deterioration in the DC superimposition characteristics. There is a risk of Furthermore, since the corners 1a have a sharp shape, as described above, when the magnetic powder 1 is coated with a binder, the uniformity of the coating film is impaired, the insulation is lowered, and the magnetic loss is reduced. It may lead to an increase.

On the other hand, when the radius R of the corner portion 1a exceeds 25 μm, the magnetic powder 1 is more spherically formed, so that the inductance is good and the DC superimposition characteristics can be improved, but the processing for the spherical shape is performed for a long time. Therefore, in this case as well, the magnetic powder 1 is likely to be greatly distorted, the coercive force Hc of the magnetic powder 1 increases, and the hysteresis loss increases, resulting in an increase in magnetic loss.

Therefore, in the present embodiment, the radius R of the corner portion 1a is set to 0.8 to 25 μm.

Further, the magnetic powder 1 is preferably subjected to heat treatment in a state after the spheroidizing treatment described below. That is, the magnetic powder 1 is obtained by applying an external force to the metal ribbon and mechanically processing the metal ribbon as described above. Specifically, since the magnetic powder 1 is obtained by pulverizing a thin metal strip, the magnetic powder 1 is likely to be distorted. Since such distortion causes an increase in magnetic loss, it is preferable to heat-treat the magnetic powder 1 obtained by pulverizing the metal ribbon. For example, by raising the temperature to about 400° C. in a short time and holding it for a short time, the distortion formed in the magnetic powder 1 can be efficiently removed, thereby reducing the coercive force Hc and reducing the hysteresis loss. Since it can be made smaller, it becomes possible to further reduce the magnetic loss.

As the magnetic powder 1, Fe—Si alloys, Fe—Si—Cr alloys, Fe—Si—Al alloys, Fe—Ni alloys, Fe—Co alloys, Fe—Si—B—Nb - Various crystalline alloy powder materials such as Cu-based alloys can be used. It is more preferable to use

Here, the term "main component" means that the Fe component is contained in the magnetic powder 1 in an amount of 60 wt % or more, preferably 80 wt % or more.

Such magnetic powder 1 preferably contains Fe, B, P, and Cu, and optionally Si and C. For example, Fe: 71 to 86 at %, B: 5 to 15 at %, P: 1 to 10 at%, Cu: 0.1 to 1.3 at%, Si: 0 to 5 at%, and C: 0 to 5 at% (however, Fe, B, P, Cu, Si, and C each at A magnetic powder compounded so that the total % is 100) can be used.

As a result, the desired magnetic properties and DC superimposition properties can be secured not only in a single amorphous phase, but also in a mixture of amorphous and nanocrystalline phases, and low magnetic loss and high mechanical strength can be obtained. A good magnetic core can be obtained.

The average particle diameter D ₅₀ of the magnetic powder 1 is not particularly limited, but usually the magnetic powder 1 having an equivalent circle diameter of 30 to 80 μm, more preferably 30 to 60 μm can be used. can.

By using this magnetic powder 1, it is possible to obtain a magnetic core with good DC superimposition characteristics and low magnetic loss. becomes possible.

FIG. 2 is a perspective view showing an embodiment of a magnetic core according to the present invention. This magnetic core 2 is formed in a ring shape having an elongated hole 2a.

FIG. 3 is a vertical cross-sectional view showing the details of the main part of the magnetic core 2. The magnetic core 2 consists of a magnetic powder 1 and two types of binders (a first binder 3 and a second binder 4). ) is formed of a composite material 5 containing

The first binder 3 is mainly made of silicone resin, and the second binder 4 is made of a resin material having higher hardness than the first binder 3 . The magnetic powder 1 is coated with the first binder 3 , and the first binders 3 are bonded to each other via the second binder 4 .

Here, the main component means that the first binder 3 contains 90 wt % or more, preferably 95 wt % or more of silicone resin.

As a result, it is possible to obtain a magnetic core 2 having good insulation properties, suppressing an increase in magnetic loss, and having good mechanical strength. That is, the silicone resin, which is the main component of the first binder 3, has excellent insulating and adhesive properties, and can form a strong film having Si—O bonds on the particle surfaces of the magnetic powder 1. . Therefore, by coating the magnetic powder 1 with the first binder 3, it is possible to suppress leakage of current from the magnetic powder 1, thereby suppressing eddy current loss. can be reduced. Then, by bonding the first binder 3 covering the magnetic powder 1 to each other through the second binder 4 having higher hardness than the first binder 3, mechanical strength such as radial crushing strength is improved. can be improved, and damage can be suppressed even when a large external force is applied.

Here, the second binder 4 is not particularly limited as long as it has a hardness higher than that of the first binder 3. A phenolic resin (Rockwell hardness: M124-128) or a polyimide resin (Rockwell hardness: M110-120) alone or a mixture thereof can be used.

The silicone resin is not particularly limited, but a methylphenyl-based silicone resin can be preferably used. The methylphenyl-based silicone resin has a small shrinkage rate of 0.1 to 0.2% when the composite material 5 is pressure-molded, and suppresses the magnetic powder 1 from being distorted during the pressure-molding. can be done. As a result, an increase in the holding force of the magnetic powder 1 can be suppressed, and an increase in hysteresis loss can be avoided, so an increase in magnetic loss can be suppressed.

The content of the first binder 3 is not particularly limited as long as desired insulation and adhesion can be secured without affecting other properties. It is preferably set to 0.5 to 1 wt%. If the content of the first binder 3 is less than 0.25 wt %, the content of the first binder 3 becomes too small, and there is a risk that sufficient insulation and adhesion cannot be ensured. On the other hand, when the content of the first binder 3 exceeds 1 wt %, the content of the magnetic powder 1 is relatively decreased, which may lead to a decrease in relative magnetic permeability.

Also, the content of the second binder 4 is not particularly limited as long as the desired mechanical strength can be secured without affecting other properties. It is preferably set to 0.5 to 1 wt%. If the content of the second binder 4 is less than 0.25 wt %, the content of the second binder 4 becomes too small, and there is a possibility that sufficient mechanical strength cannot be ensured. On the other hand, if the content of the second binder 3 exceeds 1 wt %, the content of the magnetic powder 1 is relatively decreased, which may lead to a decrease in the relative magnetic permeability.

In addition, the total content of the first and second binders 3 and 4 is not particularly limited as long as it has good insulation and good mechanical strength, but it is usually 1 to 1.75 wt%. is set to When the total content of the first and second binders 3 and 4 is less than 1 wt%, either the first binder 3 or the second binder 4 is too small to provide insulation and/or mechanical properties. It may lead to a decrease in the physical strength. On the other hand, when the total content of the first and second binders 3 and 4 exceeds 1.75 wt%, the content of the magnetic powder 1 is relatively decreased, so that relative magnetic permeability, magnetic flux saturation density, etc. It may lead to deterioration of the magnetic properties of

Further, in the above-described embodiment, the particle surfaces of the magnetic powder 1 are directly coated with the first binder 3 , but before the magnetic powder 1 is coated with the first binder 3 , the magnetic powder 1 It is also preferable to form an insulating film having a thickness of about 10 to 200 nm on the surface of the magnetic core 2, whereby the insulating properties of the magnetic core 2 can be further improved. In this case, an insulating material containing phosphoric acid or Si can be preferably used as the insulating material for forming the insulating film.

Next, a method for manufacturing the magnetic core will be described.

[Production of metal ribbon]
FIG. 4 is a diagram schematically showing one embodiment of the metal ribbon manufacturing process. In this embodiment, the metal ribbon is manufactured by a single-roll liquid quenching method.

That is, in this metal ribbon manufacturing process, a crucible 7 made of alumina or the like in which a molten metal 6 is accommodated, an induction heating coil 8 arranged on the outer periphery of the crucible 7, and an induction heating coil 8 are rotated at high speed in the direction of arrow A. It has a roll (rotating body) 9 made of Cu or the like, and a winding section 11 that rotates in the direction of arrow B and winds the thin metal strip 10 .

The thin metal ribbon 10 can be manufactured as follows.

First, as raw materials, single elements such as Fe, B, P, and Cu, which form an Fe-based metallic magnetic material, or compounds containing these elements are prepared, weighed in predetermined amounts, mixed, and heated in a high-frequency induction heating furnace or the like. It is used to heat above the melting point and then cooled to obtain the mother alloy.

Next, the master alloy is crushed and put into the crucible 7 . Then, a high-frequency power source is applied to the induction heating coil 8 to heat the crucible 7 to melt the master alloy and produce a molten metal 6 .

Next, the molten metal 6 is ejected from the nozzle 7a of the crucible 7 and dropped onto the roll 9 rotating at high speed in the arrow A direction. As a result, the molten metal 6 is rapidly solidified by the roll 9 to form an amorphous metal ribbon 10, which is wound by the winding section 11 rotating in the arrow B direction.

[Production of magnetic powder]
The metal ribbon 10 is heat-treated at a temperature of about 400° C. to precipitate a nanocrystalline phase in the amorphous phase to obtain a nanocrystallized ribbon. By pulverizing this nano-crystallized ribbon, high-quality magnetic powder 1 can be produced with high efficiency. That is, coil components are required to have good DC superimposition characteristics and low magnetic loss. A nanocrystalline alloy powder in which a nanocrystalline phase is precipitated in an amorphous phase is known as a magnetic powder suitable for such coil parts. Conventionally, this type of nanocrystalline alloy powder is produced by heat-treating an amorphous atomized powder produced by an atomizing method to precipitate a nanocrystalline phase in the atomized powder. However, in such a method, the heat treatment temperature of the atomized powder must be individually controlled with high precision, which tends to cause variations in quality and is inferior in productivity.

Therefore, in the present embodiment, by heat-treating the metal ribbon 10 and precipitating a nanocrystalline phase in the amorphous phase of the metal ribbon 10, a high-quality product can be obtained without requiring complicated temperature control or the like. It enables it to produce the magnetic substance powder 1 with high efficiency.

A method for producing the magnetic powder 1 from the metal ribbon 10 on which nanocrystals are precipitated, that is, the nanocrystallized ribbon will be described in detail below.

First, the nano-crystallized ribbon is coarsely pulverized with a coarse pulverizer such as Feather Mill (registered trademark), and then finely pulverized with an impact type fine pulverizer such as a pin mill to a roughly predetermined size. Next, a media stirring type dry pulverizer such as Attritor (registered trademark) is used to perform spheroidization treatment, and the corner 1a is machined into a curved surface so that the average particle diameter _D50 is 30 in terms of equivalent circle diameter. A magnetic powder 1 having curved corners 1a having a diameter of up to 80 μm, an aspect ratio a/b of 1.8 to 6.8, and a radius R of 0.8 to 25 μm is prepared.

Since an external force is applied to the nano-crystallized ribbon for a long time, the produced magnetic powder 1 may be distorted. It is also preferable to subject the treated magnetic powder 1 to a heat treatment. That is, for example, by raising the temperature to about 450° C. in a short time and holding it for a short time, the distortion formed in the magnetic powder 1 can be efficiently removed, the coercive force Hc is lowered, and the hysteresis loss is reduced. Since it can be suppressed, it is possible to further reduce the magnetic loss.

[Fabrication of magnetic core]
A first binder 3 is prepared, the main component of which is a silicone resin, preferably a methylphenyl-based silicone resin. Next, the content of the first binder 3 in the composite material (magnetic powder 1, first and second binders 3, 4) is preferably 0.25 to 1.0 wt%, more preferably 0.25 wt%. The first binder 3 is added to the above-described magnetic powder 1 so as to be 5 to 1.0 wt %, and a predetermined amount of a solvent such as acetone is added and mixed. Then, the solvent is removed by evaporation, and the surface of the magnetic powder 1 is coated with the first binder 3 .

Next, a second binder 4 having higher hardness than the first binder 3 such as phenol resin or polyimide resin is prepared. Next, the content of the second binder 4 in the composite material (magnetic powder 1, first and second binders 3, 4) is preferably 0.25 to 1.0 wt%, more preferably 0 .5 to 1.0 wt%, and the total content of the first and second binders 3 and 4 is preferably 1 to 1.75 wt%, coated with the first binder 3; A second binder 4 is added to the powder 1, and a predetermined amount of a solvent such as acetone is added and mixed. Then, the solvent is removed by evaporation, and the first binders 3 are bonded to each other through the second binders 4, thereby forming a composite consisting of the magnetic powder 1 and the first and second binders 3 and 4. Obtain material 5.

Next, the composite material 5 is poured into the cavity of the mold and pressurized to about 100 MPa to produce a compact.

After that, the compact is taken out from the mold and subjected to heat treatment at a temperature of 120 to 150° C. for about 24 hours to harden the first and second binders 3 and 4, thereby fabricating the magnetic core 2. do.

In the above embodiment, the solvent is removed by evaporation in the step of coating the magnetic powder 1 with the first binder 3, but the second binder 4 is added as it is without removing the solvent. After that, the solvent may be removed by evaporation to produce the composite material 5 .

Further, from the viewpoint of further improving insulation, it is also preferable to form an insulating film on the surface of the magnetic powder 1 before coating the magnetic powder 1 with the first binder 3 as described above. In that case, an insulating film can be easily formed by a known method such as a sol-gel method or a mechanochemical method using an insulating material containing phosphoric acid or Si.

FIG. 5 is a perspective view showing a reactor as an embodiment of the coil component according to the present invention. In this reactor, a coil conductor 14 is wound around a magnetic core 2 .

That is, the slot-shaped magnetic core 2 has two parallel long sides 20a and 20b. The coil conductor 14 includes a first coil conductor (primary winding) 14a wound around one long side 20a and a second coil conductor (secondary winding) wound around the other long side 20b. 14b, and a connecting portion 14c connecting the first coil conductor 14a and the second coil conductor 14b, which are integrally formed. Specifically, the coil conductor 14 is formed by coating a single rectangular wire conductor made of copper or the like with an insulating resin such as polyester resin or polyamide-imide resin. It is wound in a coil shape around the other long side portion 20b.

As described above, since the coil conductor 14 is wound around the magnetic core 2, the present reactor has high saturation magnetic flux density and low magnetic loss, good mechanical strength, ferromagnetism and small hysteresis loss. A high-purity, high-quality reactor having magnetic properties can be obtained with high efficiency.

FIG. 6 is a vertical cross-sectional view showing details of a main part of a magnetic core according to a second embodiment of the present invention.

In the second embodiment, as in the first embodiment, the surface of the magnetic powder 21 is coated with a first binder 22 containing silicone as a main component, and the first binders 22 are separated from each other. are bonded via a second binder 23 such as a phenolic resin having higher hardness than the first binder 22 . In the second embodiment, the composite material 24 is formed by the magnetic powder 21 and the first and second binders 22 and 23, and the magnetic powder 21 has cracks of 50% or more based on the quantity. 25 are formed. The cracks 25 are filled with the first binder 22 .

By forming the cracks 25 in the magnetic powder 21 in this way, the strain that may occur during pulverization or molding of the nano-crystallized ribbon is released by the cracks 25, resulting in magnetic loss caused by the strain. It is possible to effectively suppress the increase in Moreover, the formation of the cracks 25 improves the packing density of the magnetic powder 21, thereby further improving the DC superimposition characteristics and reducing the magnetic loss.

The magnetic core according to the second embodiment can be produced by the following method.

That is, by the same method and procedure as in the above-described first embodiment, the metal ribbon is heat-treated to produce a nano-crystallized ribbon, and the nano-crystallized ribbon is pulverized to produce the magnetic powder 21. do.

Next, the magnetic powder 21 is heat-treated at a temperature of about 400 to 450° C. to increase the hardness of the magnetic powder 21 and embrittle the magnetic powder 21 .

After that, the surface of the magnetic powder 21 is coated with the first binder 22 by the same method and procedure as described above, and the first binders 22 are bonded to each other via the second binder 23 to form a composite. A material 24 is produced.

The composite material 24 is then poured into a mold cavity and pressure molded. Cracks 25 are formed in the embrittled magnetic powder 21 by this pressure molding, and the cracks 25 are filled with the first binder 22 . Then, this is taken out from the mold, whereby the magnetic core of the present second embodiment in which cracks 25 are formed in 50% or more of the magnetic powder 21 on the basis of quantity is manufactured.

FIG. 7 is a vertical cross-sectional view showing details of a main part of a magnetic core according to a third embodiment of the present invention.

In the third embodiment, the gaps between the magnetic powders 31 are filled with fine particles 35 having an average particle size D ₅₀ of 1 to 50 μm. Like the magnetic powder 31, the fine particles 35 are made of a magnetic metal material containing Fe as a main component. Then, as in the first and second embodiments, the surface of the magnetic powder 31 is coated with a first binder 32 containing silicone as a main component, and the first binders 32 are bonded to each other. are joined via a second binder 33 such as a phenolic resin having a hardness higher than that of the binder 32 . In the third embodiment, a composite material 34 is formed of fine particles 35 in addition to magnetic powder 31 , first and second binders 32 and 33 .

Although the method for producing the fine particles 35 is not particularly limited, atomized powder produced by atomization is preferred, and atomized powder produced by water atomization is more preferred. The water atomization method uses water as the jet fluid, so unlike the gas atomization method, which uses an inert gas as the jet fluid, high-pressure atomization is possible and powder particles with a small average particle size _D50 can be produced. , and the fine particles 35 can be efficiently filled in the gaps between the magnetic powders 31 produced from the metal ribbon 10 .

By including the above-described fine particles 35 in the magnetic core in this way, the fine particles 35 are present in the gaps between the magnetic powders 31, so that the DC superimposition characteristics and the relative magnetic permeability can be further improved. .

Then, the magnetic core according to the third embodiment can be manufactured by the following method.

That is, by the same method and procedure as in the first embodiment, the metal ribbon 10 is heat-treated to produce a nano-crystallized ribbon, and the nano-crystallized ribbon is pulverized to obtain the magnetic powder 31. make.

Next, a magnetic metal material containing Fe as a main component is prepared, and fine particles 35 are produced preferably by an atomization method, more preferably by a water atomization method.

Next, the magnetic powder 31 and the fine particles 35 are mixed in the same manner and procedure as described above, and then the first binder 32 is added in a solvent to cover the surface of the magnetic powder 31 with the first binder 32. After coating, a second binder 33 is added, thereby bonding the first binders 32 together through the second binder 33 .

After that, it is poured into a mold cavity and pressure-molded, and after pressure-molding, the molded body is taken out from the mold, whereby the magnetic core of the present third embodiment can be manufactured.

In this case, before mixing the magnetic powder 31 and the fine particles 35, the magnetic powder 31 is preferably heat-treated to increase the hardness of the magnetic powder 31 and make it brittle. As a result, as in the second embodiment, cracks are formed in the magnetic powder 31 by pressure molding. will be released by

It should be noted that the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention.

In each of the above embodiments, the second binders 4, 23, 33 are formed so as to cover the entire outer surfaces of the first binders 3, 22, 32. The first binders 3, 22, 32 may not be entirely covered with 23, 33, and the first binders 3, 22, 32 are separated from each other via the second binders 4, 23, 33 It is sufficient if they are connected.

In the second embodiment, the magnetic powder 21 is heat-treated before adding the first and second binders 22 and 23 to increase the hardness of the magnetic powder 21. By devising, the nanocrystalline phase may be precipitated in the amorphous phase during the heat treatment of the metal ribbon 10, and the hardness may be increased at the same time.

In addition, in the above-described embodiments, a reactor was exemplified as a coil component using magnetic powder, but it goes without saying that the present invention can also be applied to other coil components such as an inductor.

Furthermore, with respect to the elemental species constituting the present magnetic powder, elements having an amorphous forming ability, such as _Ga , Ge, and Pd, may be added as appropriate. Even if it contains impurities of , it does not affect the characteristics.

In addition, in the above-described embodiment, the metal ribbon is manufactured by heating and melting the mixture by high-frequency induction heating, but the heating and melting method is not limited to high-frequency induction heating. There may be.

Next, examples of the present invention will be specifically described.

[Preparation of sample]
Fe, Si, B, and Fe ₃ P are prepared as raw materials, blended so as to have a predetermined composition, heated to a melting point or higher in a high-frequency induction heating furnace to melt, and then the melt is poured into a copper casting mold. It was poured and cooled to produce a master alloy.

Next, this master alloy was crushed to a size of about 5 mm, put into a crucible of a single-roll liquid quenching apparatus, and subjected to high-frequency induction heating to melt the master alloy to obtain a metal melt.

Next, the metal melt is ejected from the tip nozzle of the crucible, poured into a roll rotating at high speed and rapidly solidified, thereby forming a continuous metal strip having a width of 50 mm and a thickness of 20 to 30 μm. was made.

Next, the metal ribbon is passed through a heating furnace adjusted to a temperature of 400 ° C., the metal ribbon is heat-treated to precipitate a nanocrystalline phase in the amorphous phase, and then pulverized to obtain an average particle size. A magnetic powder having a D ₅₀ of about 60 μm in terms of equivalent circle diameter was prepared.

Next, a methylphenyl-based silicone resin (first binder) is prepared, weighed so that the content of the sample after pressure molding is as shown in Table 1, a predetermined amount of acetone is added, and mixed. did. Thereafter, acetone was removed by evaporation to prepare powder samples of sample numbers 1 to 9.

Observation of each powder sample of sample numbers 1 to 9 with a microscope revealed that silicone resin was coated on the surface of the magnetic powder in sample numbers 2 to 9, except for sample number 1 in which silicone resin was not added. was confirmed.

Next, a phenolic resin (second binder) was prepared, weighed so that the content of the pressure-molded sample would be as shown in Table 1, and a predetermined amount of acetone was added and mixed. After that, acetone was removed by evaporation, and composite materials of sample numbers 1 to 9 were produced.

Next, the composite material was poured into the cavity of the mold and pressurized to about 100 MPa to produce a compact. After that, the molded body is taken out from the mold and subjected to heat treatment at a temperature of 120 to 150° C. for about 24 hours to cure the silicone resin and phenol resin. (magnetic core) was produced. The external dimensions of the prepared sample were 8 mm in outer diameter, 4 mm in inner diameter, and 2.5 mm in thickness.

[Sample evaluation]
(Measurement of powder resistance)
10 g of each mixture was prepared by mixing the silicone resin and the phenol resin so that the mixing ratio of the silicone resin and the phenol resin was as shown in Table 1. Then, using a powder resistance measurement system (MCP-PD51, manufactured by Mitsubishi Chemical Analytech), the powder resistance of these mixtures was measured.

(Measurement of core loss)
For each of the three samples of sample numbers 1 to 9, 8 turns of the primary winding that will be the first coil conductor and 8 turns of the secondary winding that will be the second coil conductor are wound, and a BH analyzer (Iwasaki communication A magnetic field of 100 mT was applied at a measurement frequency of 100 kHz using SY-8218 manufactured by Kisha, and the core loss was measured, and the average value of three samples was obtained.

(Measurement of radial crushing strength)
The radial crushing strength of each of the three samples of sample numbers 1 to 9 was measured using a precision universal tester (Autograph AGS-5kNX manufactured by Shimadzu Corporation), and the average value of each of the three samples was obtained.

(Measurement result)
Table 1 shows the measurement results of silicone resin, phenolic resin, total content, powder resistance, core loss, and radial crushing strength of each of samples Nos. 1 to 9.

Samples Nos. 1 to 5 have a constant phenolic resin content of 0.75 wt % and different silicone resin contents within a range of 0 to 1.0 wt %.

Sample No. 1 contains 0.75 wt% of a phenolic resin having a hardness higher than that of a silicone resin, so although the radial crushing strength is 16 N/mm ² and the mechanical strength is good, it does not contain a silicone resin. As a result, the powder resistance was as low as 1.0×10 Ω·cm and the insulation was poor, and current leakage increased eddy current loss, resulting in a large core loss of 1000 kW/m ³ .

On the other hand, Sample Nos. 2 to 5 contain 0.25 to 1.0 wt % of silicone resin in addition to 0.75 wt % of phenol resin, so the powder resistance is 1.0×10 ³ to 1.0 wt %. It has a large resistance of 0×10 ⁷ Ω·cm and good insulation, which suppresses current leakage, reduces eddy current loss, and secures a good radial crushing strength (mechanical strength) of 16 to 18 N/mm ² . It was possible to reduce the core loss to 900 to 520 kW/m ³ while maintaining the In particular, sample numbers 3 to 5 had a high silicone resin content of 0.5 to 1.0 wt%, so the powder resistance was stable at 1.0×10 ⁶ to 1.0×10 ⁷ Ω·cm. The core loss was reduced to 650 kW/m ³ or less because sufficient insulation was ensured.

Sample Nos. 6 to 9 have a constant silicone resin content of 0.75 wt % and a different phenol resin content within a range of 0 to 1.0 wt %.

Sample No. 6 contains 0.75% by weight of silicone resin, so it has a high powder resistance of 1.0×10 ⁷ Ω·cm, good insulation, and a low core loss of 550 kW/m ³ . , the radial crushing strength was 7 N/mm ² , indicating that the mechanical strength was poor because no high-hardness phenolic resin was contained.

On the other hand, sample numbers 7 to 9 contain 0.25 to 1.0 wt% of phenolic resin in addition to 0.75 wt% of silicone resin, so the radial crushing strength is 10 to 18 N/mm ² and 530 Good mechanical strength could be obtained while ensuring a low core loss of ~560 kW/m ³ . In particular, sample numbers 8 to 9 have a high phenolic resin content of 0.5 to 1.0 wt%, so the radial crushing strength is 16 to 18 N/mm ² , and better mechanical strength can be obtained. I found out.

FIG. 8 is a diagram showing the relationship between the content of silicone resin and powder resistance when the content of phenol resin is constant, and FIG. 9 shows the relationship between the content of silicone resin and core loss in that case. FIG. 4 is a diagram showing; In the figure, the horizontal axis indicates the silicone resin content (wt%), and the vertical axis indicates the powder resistance (Ω·cm) (Fig. 8) and the core loss (kW/m ³ ) (Fig. 9). there is

As is clear from FIG. 8, as the content of the silicone resin increases, the powder resistance also increases. It's becoming

Moreover, as is clear from FIG. 9, the core loss decreases as the silicone resin content increases, indicating that there is a correlation between the two.

FIG. 10 is a diagram showing the relationship between the content of silicone resin and radial crushing strength when the content of phenol resin is constant. In the figure, the horizontal axis indicates the content (wt%) of the silicone resin, and the vertical axis indicates the radial crushing strength (N/mm ² ).

As is clear from FIG. 10, samples Nos. 1 to 5 contain 0.75 wt % silicone resin, and therefore have good radial crushing strength of 16 to 18 N/mm ² . When the content was 0.5 wt % or more, the radial crushing strength was slightly improved, and it was found that the silicone resin can also contribute to the improvement of the radial crushing strength depending on the content.

FIG. 11 shows the relationship between the phenolic resin content and the powder resistance when the silicone resin content is constant, and FIG. 12 shows the relationship between the phenolic resin content and the core loss in that case. FIG. 4 is a diagram showing; In the figure, the horizontal axis indicates the phenolic resin content (wt%), and the vertical axis indicates the powder resistance (Ω·cm) (Fig. 11) and the core loss (kW/m ³ ) (Fig. 12). there is

As is clear from FIG. 11, since the content of the silicone resin is constant at 0.75 wt %, the powder resistance is also constant at 1.0×10 ⁷ Ω·cm.

Moreover, as is clear from FIG. 12, the core loss is also maintained substantially constant at 530 to 560 kW/m ³ , suggesting that there is a correlation between the two.

FIG. 13 is a diagram showing the relationship between the content of phenolic resin and radial crushing strength when the content of silicone resin is constant. In the figure, the horizontal axis indicates the content (wt%) of the phenolic resin, and the vertical axis indicates the radial crushing strength (N/mm ² ).

As is clear from FIG. 13, as the phenolic resin content increases, the radial crushing strength improves, and when the phenolic resin content exceeds 0.5 wt %, the radial crushing strength gradually increases.

It is possible to realize a magnetic core with small magnetic loss and good mechanical strength, and a coil component such as a reactor using this magnetic core.

1 magnetic powder 2 magnetic core 3 first binder 4 second binder 5 composite material 6 metal melt (melt)
10 Metal ribbon 14 Coil conductor 21 Magnetic powder 22 First binder 23 Second binder 24 Composite material 31 Magnetic powder 32 First binder 33 Second binder 34 Composite material

Claims (14)

A magnetic core made of a composite material containing magnetic powder and a binder,
The binder comprises a first binder containing a silicone resin as a main component, and a second binder comprising at least one resin having a hardness higher than that of the first binder. along with
The content of the first binder is 0.25 to 1 wt%, the content of the second binder is 0.25 to 1 wt%, and the first and second binders are , the total content is 1 to 1.75 wt%,
A magnetic core, wherein the magnetic powder is coated with the first binder, and the first binders are bonded to each other via the second binder. 2. A magnetic core according to claim 1 , wherein said second binder contains at least one of phenolic resin and polyimide resin. 3. A magnetic core according to claim 1 , wherein said silicone resin is of the methylphenyl type. 4. The magnetic core according to claim 1 , wherein the content of said first binder is 0.5 wt % or more. 5. The magnetic core according to claim 1 , wherein the content of said second binder is 0.5 wt % or more. 6. A magnetic core according to claim 1 , wherein a film made of an insulating material is formed on the surface of said magnetic powder. 7. The magnetic core according to claim 1 , wherein said magnetic powder contains Fe as a main component and includes a mixture of an amorphous phase and a nanocrystalline phase. 8. The magnetic core according to claim 1 , wherein the magnetic powder has an average particle size of 30 to 80 μm in terms of equivalent circle diameter. a step of producing a magnetic powder;
a step of mixing a first binder containing a silicone resin as a main component and the magnetic powder, and coating the magnetic powder with the first binder;
The magnetic powder coated with the first binder and a second binder made of at least one kind of resin having higher hardness than the first binder are mixed to form the first binder. bonding together via the second binder to produce a composite material containing the magnetic powder and the first and second binders;
and pressing the composite material to produce a magnetic core. including
In the step of producing the composite material, the total content of the first and second binders is defined in the range of 1 to 1.75 wt%, and the content of the first binder in the composite material A step of adding the first binder to the magnetic powder so that the content is 0.25 to 1.0 wt%, and coating the magnetic powder with the first binder; The second binder is added to the magnetic powder coated with the first binder so that the content of the second binder is 0.25 to 1.0 wt%, and the first binder is added. and bonding the binders together via the second binder. A method of manufacturing a magnetic core, characterized by: 10. The method of manufacturing a magnetic core according to claim 9 , wherein the second binder contains at least one of phenolic resin and polyimide resin. 11. The method of manufacturing a magnetic core according to claim 9 , further comprising the step of applying an insulating material to the surface of said magnetic powder to form an insulating coating. The step of producing the magnetic powder comprises weighing and mixing predetermined raw materials containing at least an Fe component, heating the prepared mixture to prepare a melt, and heating the melt. A step of ejecting onto a rotating body and quenching and solidifying to produce a metal ribbon, and heat-treating the metal ribbon to obtain a nano-crystallized ribbon mainly composed of Fe in which nanocrystals are precipitated in an amorphous phase. 12. The method for manufacturing a magnetic core core according to claim 9 , comprising the step of manufacturing, and the step of pulverizing the nano-crystallized ribbon to manufacture the magnetic powder. A coil component comprising the magnetic core according to any one of claims 1 to 8 and a coil conductor. 14. The coil component according to claim 13 , wherein the coil conductor is wound around the magnetic core.

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