JP2022136806A - Inductor and manufacturing method thereof - Google Patents

Abstract

To provide an inductor capable of suppressing cracks that occur in a core.SOLUTION: An inductor 10 includes a core 12 in which a planarly extending coil conductor 11 is embedded. The coil conductor 11 has a horizontally flat elliptical cross-sectional shape perpendicular to the plane extending direction. The core 12 has a magnetic metal body with a filling rate of 80 volume% or more and less than 100 volume%. The magnetic metal body bites into a portion of the total length of 75% or more and 100% or less of the circumference of the elliptical outer circumference in the cross-sectional shape of the coil conductor 11.SELECTED DRAWING: Figure 2

Description

The present invention relates to inductors and methods of manufacturing the same.

A typical conventional inductor consists of a core made of a ferromagnetic material or a ferrimagnetic material wound with a wire made of an electric conductor in a coil shape. In recent years, an inductor has been proposed that has a dust core in which a coil conductor is embedded in a magnetic metal powder that has a high saturation magnetic flux density in a high-frequency current, in order to be suitable for use in the power supply circuit of a computer that operates in a high-frequency range. (See Patent Document 1, for example).

Patent Document 2 discloses a technique for obtaining a core that is highly filled with magnetic metal powder by performing pressure molding until the magnetic metal powder bites into the surface of the coil conductor.

Japanese Patent Publication No. 2019-530217 WO2009/075110

However, in the techniques disclosed in Patent Documents 1 and 2, the coil conductor is a rectangular wire having a rectangular cross section, and the problem is that cracks starting from the corners of the coil conductor tend to occur in the core during pressure molding. There is In the technique disclosed in Patent Document 2, the internal distortion of the magnetic metal powder is removed by heating after pressure molding, but it is difficult to eliminate cracks.

SUMMARY OF THE INVENTION In view of the above points, it is an object of the present invention to provide an inductor capable of suppressing cracks occurring in the core, and a method of manufacturing the same.

An inductor of the present invention is an inductor comprising a core in which a coil conductor extending on a plane is embedded, wherein the coil conductor has a cross-sectional shape perpendicular to the extending direction having a long axis on the plane. The core has an elliptical shape, the core has a magnetic metal body with a filling rate of 80% by volume or more and less than 100% by volume, and the total circumference of the outer circumference of the ellipse in the cross-sectional shape of the coil conductor is 75% or more. It is characterized in that the magnetic metal body bites into a portion of 100% or less of the length.

According to the inductor of the present invention, since the cross-sectional shape of the coil conductor is elliptical and there are no corners, it is possible to suppress the occurrence of cracks that tend to occur in the core starting from the corners. In addition, the filling rate of the magnetic metal body in the core is as high as 80% by volume or more, making it possible to obtain an inductor with high inductance. Furthermore, since the magnetic metal body bites into a portion of the total length of 75% or more and 100% or less of the circumference of the elliptical outer circumference in the cross-sectional shape of the coil conductor, the adhesion between the coil conductor and the core is high.

Note that the cross-sectional shape of the coil conductor may not be strictly elliptical because the magnetic metal body may bite into from the outer periphery thereof, and may not be line-symmetrical in the horizontal and vertical directions. The elliptical shape that defines the circumference of the outer circumference is the closest elliptical shape obtained by using the method of least squares after regarding the actual cross-sectional shape of the coil conductor as an aggregate of many points. As the least-squares method, for example, a linear least-squares method, a multivariate linear least-squares method, or a multivariate nonlinear least-squares method may be used. The length of the portion in which the magnetic metal body is biting means the length of the outer periphery of the portion where the magnetic metal body exists on or inside the approximate elliptical outer periphery.

In the inductor of the present invention, it is preferable that the magnetic metal body is made of Fe-based amorphous powder.

In this case, when the core is formed by pressure molding, heating at a temperature exceeding the softening temperature of the Fe-based amorphous during pressure molding softens the Fe-based amorphous and facilitates deformation of the coil conductor. It is possible to further suppress the occurrence of cracks in the core.

Moreover, in the inductor of the present invention, it is preferable that the surface roughness Rz of the actual circumference of the cross-sectional shape of the coil conductor is 5 μm or more and 40 μm or less.

In this case, if the surface roughness Rz of the actual outer circumference in the cross-sectional shape of the coil conductor exceeds 40 μm, the DC resistance increases, and if it is less than 5 μm, deformation becomes insufficient. Note that the actual outer circumference of the cross-sectional shape of the coil conductor is the actual outer circumference of the cross-sectional shape of the coil conductor, and is not the elliptical outer circumference approximated as described above. Then, the surface roughness Rz of the actual outer circumference is calculated as a ten-point average roughness using a roughness curve that indicates the deviation in the direction perpendicular to the average line of the outer circumference of the approximate ellipse described above. Just do it.

In addition, in the inductor of the present invention, it is preferable that the total length of the actual outer circumference of the cross-sectional shape of the coil conductor is 1.1 times or more and 2.5 times or less of the total length of the outer circumference of the elliptical shape.

In this case, if the total length of the actual outer circumference in the cross-sectional shape of the coil conductor is less than 1.1 times the total length of the outer circumference of the elliptical shape, the deformation becomes insufficient, and if it exceeds 2.5 times, the DC resistance increases. This is because a problem arises.

Further, in the inductor of the present invention, an insulator having a thickness equal to or less than the average grain size of the magnetic metal body may be present on the outer circumference of the ellipse in the cross-sectional shape of the coil conductor. As the average particle diameter of the magnetic metal body, the median diameter D50 at which the cumulative particle size frequency is 50% may be used.

In this case, the adhesion between the coil conductor and the core is maintained to some extent by the insulator. It should be noted that this insulator remains, for example, when the insulator film covering the surface of the coil conductor is formed by hot-pressing the core.

Further, in the inductor of the present invention, the elliptical cross-sectional shape in the vertical direction orthogonal to the extending direction of the coil conductor preferably has a major axis that is 1.3 to 2.0 times as large as a minor axis.

In this case, if the core is pressurized vertically in a state where the coil conductor made of round wire is embedded, the core is sufficiently pressurized, and cracks occurring in the core can be suppressed. becomes.

The filling rate of the magnetic metal bodies in the core positioned in the horizontal direction of the coil conductor is 0.8 to 1.0 times the filling rate of the magnetic metal bodies in the core positioned in the vertical direction of the coil conductor. The following are preferable.

In this case, when the core is formed by pressing in the vertical direction while the coil conductor is embedded, the core is uniformly pressed.

In the inductor manufacturing method of the present invention, a raw material powder containing a magnetic metal powder and a binder is filled in a mold while a coil conductor extending on a plane is embedded so that the plane is horizontal. and pressing the metal mold filled with the raw material powder in the vertical direction while heating, so that the cross-sectional shape of the coil conductor perpendicular to the extending direction is an ellipse having a long axis on the plane. and deforming to become.

According to the inductor manufacturing method of the present invention, since the cross-sectional shape of the coil conductor is changed from a circular shape to an elliptical shape and there are no corners, it is possible to suppress the occurrence of cracks that tend to occur in the core starting from the corners. become.

In the inductor manufacturing method of the present invention, it is preferable that the magnetic metal powder is made of Fe-based amorphous material, and that the heating temperature in the heating exceeds the softening temperature of the Fe-based amorphous material.

In this case, the heating softens the Fe-based amorphous material, facilitating deformation of the coil conductor, so that cracks in the core can be further suppressed.

In the method of manufacturing an inductor according to the present invention, preferably, the surface of the coil conductor is covered with an insulating film, and the heating temperature in the heating exceeds the heat resistance temperature of the insulating film.

In this case, all or most of the insulating film disappears by heating, so that it is possible to improve the adhesion between the coil conductor and the core.

FIG. 4 is a cross-sectional explanatory diagram showing a method of manufacturing an inductor according to an embodiment of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory cross-sectional view showing an inductor according to an embodiment of the present invention; FIG. 3 is an explanatory cross-sectional view schematically showing an enlarged periphery of the coil conductor in FIG. 2 ; FIG. 3 is a cross-sectional photographic view of inductors in Examples 1 to 3; FIG. 11 is a cross-sectional photographic view of inductors in Examples 4 and 5; FIG. 4 is a cross-sectional photographic view of inductors in Comparative Examples 1 to 3;

A method of manufacturing an inductor according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. This manufacturing method is a method for manufacturing an inductor 10 according to an embodiment of the present invention, which will be described later. and a hot pressure forming step of performing hot pressure (hot press) forming using the hot press forming process. 1 to 3 are diagrams for schematically explaining the embodiment, and the dimensions are deformed.

In the preparation step, first, the raw material powder 2 for forming the core 12 is prepared. The raw material powder 2 is, for example, a granulated powder produced by mixing a magnetic metal powder, a binder, and the like.

The magnetic metal powder is, for example, Fe-based soft magnetic metal powder, and includes Fe, Fe—Si, Fe—Ni, Fe—Ni—Mo, Fe—Si—Al, Fe—Si—Cr, Fe A metal powder made of an Fe-based soft magnetic material containing at least one selected from Fe-based soft magnetic nanocrystals and Fe-based soft magnetic nanocrystals. When the magnetic metal powder contains two or more of these materials, the ratio is not limited.

The Fe-based amorphous is amorphous without a crystal structure. Fe-based amorphous is particularly preferable as a magnetic metal powder because its softening temperature is lower than the heating temperature in the hot pressure forming process and softens during hot pressure forming to prevent deformation of the coil conductor 1 .

The magnetic metal powder has a particle size of, for example, 1 μm or more and 100 μm or less, more preferably 1 μm or more and 50 μm or less. The particle size distribution of the magnetic metal powder may have one or more peaks. In particular, when the magnetic metal powder is an Fe-based amorphous powder, it is softened by heating during hot pressure molding, and the filling rate of the magnetic metal powder is necessarily improved by having a plurality of peaks in the particle size distribution. No need.

A thermosetting resin is suitable for the binder, and the type of the resin may be appropriately selected according to the use of the inductor 10 or the like. Resins used as binders include, but are not limited to, epoxy resins, phenol resins, silicone resins, melamine resins, polyurethane resins, polyimide resins, alkyd resins, unsaturated polyester resins, and the like.

The amount of the binder added to the magnetic metal powder is preferably 10% by weight or less, more preferably 0.4% by weight or more and 5% by weight or less. Furthermore, the raw material powder 2 may contain dispersants, lubricants, auxiliaries, and the like in order to impart arbitrary functionality to the extent that the effects of the present invention are not impaired.

Then, the raw material powder 2 is filled up to a predetermined height in a mold 3 having a shape that follows the outer shape of the core 12 and having high heat resistance, and the upper surface is leveled.

Next, the coil conductor 1 is placed on the raw material powder 2 whose upper surface is flattened.

The coil conductor 1 is a conductor that constitutes the coil of the inductor 10, and is made of, for example, a metal conductor, but is particularly preferably made of copper or a copper alloy so as to be easily deformed in the hot pressing process.

The coil conductor 1 is composed of a single round wire having a circular cross section perpendicular to the extending direction (hereinafter referred to as a vertical cross section). Then, the coil conductor 1 is bent on a plane so that the round wire is formed into an arbitrary unicursal shape such as a zigzag shape, a wave shape, an S shape, a Z shape, an N shape, an arc shape, and a spiral shape. extended. That is, the coil conductor 1 is a planar coil whose centerline is located on a predetermined plane. A coil conductor extending on a plane is embedded in the raw material powder 2 so that the plane is horizontal. Although not shown, both ends of the coil conductor 1 are provided with external connections such as lead frames.

The diameter of the vertical cross section of the coil conductor 1 is, for example, 0.3 mm or more and 3 mm or less, more preferably 0.5 mm or more and 2 mm or less. However, the vertical cross section of the coil conductor 1 is not necessarily limited to a perfect circular shape, and may be a flattened shape such as an elliptical shape.

In order to prevent the surface from being oxidized until the hot pressure molding process, which will be described later, the surface of the coil conductor 1 is preferably covered with an insulating film 4 . The insulating film 4 is made of, for example, an insulating resin such as polyurethane or polyamide-imide whose heat resistance temperature is lower than the heating temperature in the hot pressure molding process, for example, 500° C. or lower, more preferably 300° C. or lower. The thickness of the insulator film 4 may be determined so that all or most of the insulator film 4 disappears in the hot pressure molding process. It is preferably 15 μm or less.

Next, the raw material powder 2 is also added onto the coil conductor 1 to fill the inside of the mold 3 with the raw material powder 2 . Thereby, the coil conductor 1 is embedded in the raw material powder 2 . However, the connecting portions at both ends of the coil conductor 1 are exposed from the raw material powder 2 .

Next, for example, a heating temperature of 200° C. to 550° C., more preferably 400° C. to 500° C., a heating time of 30 seconds to 15 minutes, more preferably 30 seconds to 5 minutes, 4 t/cm ² or more A hot pressure molding step is performed in which pressure is applied while heating with a pressure of 15 t/cm ² or less, more preferably 6 t/cm ² or more and 10 t/cm ² or less. The pressing direction is vertical.

It is preferable to apply pressure simultaneously in both vertical directions using an upper punch and a lower punch. However, the pressure may be applied in either one of the upward direction and the downward direction, or a time difference may be provided between the upward and downward pressures. In addition, it is preferable to heat by a heater (not shown) provided in the pressurizer at the time of pressurization.

Thereby, the inductor 10 according to the embodiment of the present invention is obtained. As will be described below, the inductor 10 has a core 12 that includes a powdered magnetic metal body formed by hot pressing, and a coil conductor 1 that has an elliptical cross-sectional shape in the vertical direction. The coil conductor 11 is transformed into a coil conductor 11, and the powdery magnetic metal material bites into at least a part of the surface of the coil conductor 11, so that the coil conductor 11 and the core 12 are in close contact with each other with almost no gap. become a thing.

An inductor 10 according to an embodiment of the present invention will be described below. This inductor 10 is a 1T inductor in which the coil conductor 1 has one turn.

The inductor 10 has a coil conductor 11 having an elliptical cross section in the vertical direction embedded in a core 12, and has a magnetic metal filling rate of 80% by volume or more and less than 100% by volume, resulting in high inductance.

3 to 5, the inductor 10 has powdered magnetic metal in a total length of 75% or more and 100% or less of the circumference of the elliptical outer circumference in the cross-sectional shape of the coil conductor 11. The body bites into the coil conductor 11 and the core 12 has high adhesion.

Note that the cross-sectional shape of the coil conductor 11 does not have to be strictly elliptical, such as a magnetic metal body biting in from the outer periphery, and it does not have to be line-symmetrical in the horizontal and vertical directions. The elliptical shape that defines the circumference of the outer circumference is the closest elliptical shape that can be obtained by using the method of least squares, assuming that the actual cross-sectional shape of the coil conductor 11 is an aggregate of many points. As the least-squares method, for example, a linear least-squares method, a multivariate linear least-squares method, a multivariate nonlinear least-squares method, or the like may be used. The length of the part where the magnetic metal body is biting means the length of the outer periphery of the part where the magnetic metal body exists on or inside the approximate ellipse.

In order to obtain high inductance, the filling rate of the magnetic metal body in the core 12 is 80% by volume or more, and more preferably 90% by volume or more. The filling rate of the magnetic metal body can be calculated based on the density obtained by actually measuring the partially cut core 12 .

The powdery magnetic metal body that has bitten into the surface of the coil conductor 11 may be the magnetic metal powder described above remaining in its original shape. The powdery magnetic metal material that bites into the surface of the coil conductor 11 has a particle size of, for example, 1 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less.

Further, the surface roughness Rz of the actual circumference of the cross-sectional shape of the coil conductor 11 is, for example, 5 μm or more and 40 μm or less, and more preferably 5 μm or more and 30 μm or less. This is because if the surface roughness Rz of the actual circumference exceeds 40 μm, the direct current resistance increases, and if it is less than 5 μm, deformation becomes insufficient. The total length of the actual outer circumference of the coil conductor 11 in cross section is, for example, 1.1 times or more and 2.5 times or less of the total length of the outer circumference of the elliptical shape.

Note that the actual outer circumference of the cross-sectional shape of the coil conductor 11 is the actual outer circumference of the cross-sectional shape of the coil conductor 11, and is not the approximate elliptical outer circumference as described above. Then, the surface roughness Rz of the actual outer circumference is calculated as the ten-point average roughness by using a curve representing the deviation in the direction perpendicular to the average line when the outer circumference of the approximated ellipse is taken as the average line. Just do it.

The major axis (width) in the horizontal direction (direction perpendicular to the pressing direction) with respect to the minor axis (height) h of the approximated ellipse in the vertical direction (pressing direction) orthogonal to the extending direction of the coil conductor 11 The ratio of w is, for example, 1.3 or more and 2.0 or less, more preferably 1.5 or more and 1.8 or less for the long diameter w to 1 for the short diameter h. As a result, an appropriate pressurizing force acts and the magnetic metal body is highly filled, making it possible to obtain an inductor 10 with a high inductance. Furthermore, while the occurrence of a gap between the magnetic metal body and the coil conductor 11 is suppressed, the occurrence of cracks in the core 12 is also suppressed.

In addition, the ratio of the filling rate of the magnetic metal bodies existing in the vertical direction and the horizontal direction of the coil conductor 11 is 1 in the vertical direction and 0.8 or more and 1.0 or less in the horizontal direction, and more preferably. It is 0.9 or more and 1.0 or less. Furthermore, the difference between the upward and downward directions and the difference between one and the other in the horizontal direction is, for example, 10% or less, more preferably 5% or less. As a result, an appropriate pressurizing force acts and the magnetic metal body is uniformly highly filled, making it possible to obtain the inductor 10 with a high inductance. Moreover, the formation of a gap between the magnetic metal body and the coil conductor 11 is suppressed.

Note that the insulator film 4 may remain on the surface of the coil conductor 11 . The remaining insulator film 4 may exist on the outer periphery of the cross section of the coil conductor 11 with a thickness equal to or less than the average particle size of the powdered magnetic metal. As the average particle diameter of the magnetic metal body, the median diameter D50 at which the cumulative particle size frequency is 50% may be used. Moreover, the thickness of the remaining insulator film 4 is preferably 10 μm or less.

As described above, the coil conductor 1 made of a round wire is embedded in the raw material powder 2 and hot-pressed, so that the vertical cross section of the coil conductor 11 has a substantially elliptical shape. Therefore, unlike the conventional case where the coil conductor is made of a rectangular wire, since the coil conductor 11 does not have corners, it is possible to suppress the occurrence of cracks that tend to occur in the core 12 starting from the corners. Become. The coil conductor 1 before hot pressure forming does not necessarily have to be a round wire. It is desirable to have a round wire or a conductor with a cross section close to a circle before compression molding.

Furthermore, since the coil conductor 1 has a circular vertical cross section, it is easily flattened in the horizontal direction and deformed into an elliptical shape when pressure is applied from the vertical direction. In addition, since the magnetic metal powder also moves due to this deformation, the filling rate of the magnetic metal body is improved.

For example, if the coil conductor 1 is a rectangular wire as in the prior art, it is difficult to deform so as to extend further in the horizontal direction, and even if the coil conductor 1 is deformed, there is a risk of cracks occurring in the core 12 due to springback. .

Furthermore, when the magnetic metal powder is amorphous metal powder, if the heating temperature in the hot pressing process is higher than the softening temperature, the amorphous metal powder will soften and the deformation of the coil conductor 1 will not be hindered, and the pressing force can be applied in the horizontal direction. Since the core 12 is made uniform by being affected by the heat, it becomes possible to further suppress the occurrence of cracks.

Furthermore, by performing hot pressure molding at a heating temperature exceeding the heat resistance temperature of the insulating film 4 covering the surface of the coil conductor 1, it is possible to eliminate all or most of the insulating film 4, Since the magnetic metal grains bite into the coil conductor 11 , it is possible to improve the adhesion between the coil conductor 11 and the core 12 .

It should be noted that the present invention is not limited to the above, and can be modified as appropriate. For example, although the coil conductor 11 extends on the horizontal plane, the plane on which the coil conductor 11 extends may be an inclined plane, a vertical plane, or the like.

(Examples 1 to 5, Comparative Examples 1 to 3)
As the raw material powder 2, granulated amorphous metal powder was used as magnetic metal powder, and epoxy resin was used as a binder. The amount of the binder added to the magnetic metal powder was 0.4% by weight. The magnetic metal powder had a first crystallization temperature of 400°C and a second crystallization temperature of 500°C.

In Examples 1 to 5 and Comparative Examples 1 to 3, the coil conductor 1 was a straight rod with a length of 50 mm.

In Examples 1 to 5, a round wire made of copper and having a circular cross section was used as the coil conductor 1 . The cross-sectional diameters were 0.10 mm for Example 1, 0.37 mm for Example 2, 0.50 mm for Example 3, 0.17 mm for Example 4, and 0.26 mm for Example 5. The surfaces of the coil conductors 1 of Examples 1 to 3 were covered with a polyurethane film 4 having a thickness of 12 μm and a heat resistance temperature of 130° C. as an insulating film 4 . Further, the surfaces of the coil conductors 1 of Examples 4 and 5 were coated with polyamide-imide having a thickness of 7 μm and 20 μm and having a heat resistance temperature of 220° C. as an insulating film 4 .

In Comparative Examples 1 to 3, a flat wire made of copper and having a rectangular cross section was used as the coil conductor 1 . The height and width of the cross section are 0.1 mm in height and 1.0 mm in width in Comparative Example 1, 0.16 mm in height and 1.27 mm in width in Comparative Example 2, and 0.45 mm in height and 1 mm in width in Comparative Example 3. 0.8 mm. Then, the surfaces of the coil conductors 1 of Comparative Examples 1 to 3 were covered with a polyamideimide film 4 having a thickness of 15 μm and a heat resistance temperature of 220° C. as an insulating film 4 .

The mold 3 was filled with the raw material powder 2 so that the coil conductor 1 extends horizontally in the center. This completes the preparation process.

Next, a hot pressure molding step was performed. As a result, the inductor 10 having the coil conductor 11 embedded in the core 12 was obtained. Then, the inductor 10 was cut so that the vertical surface was exposed, and the cut surface was observed with an electron microscope.

In Examples 1 to 3, as shown in FIG. 4, the coil conductor 11 has a substantially elliptical vertical cross-section, and the powdery magnetic metal material bites into the surface thereof, so that the gap between the coil conductor 11 and the core 12 is formed. was found to be small.

In Examples 4 and 5, as shown in FIG. 5, it was found that the coil conductor 11 had a substantially elliptical vertical cross-section, and the surface of the coil conductor 11 was bitten by powdered magnetic metal. However, in a microscope photograph at a magnification of 300 times, the insulating film 4 remains in the upper right portion of the cross section of the coil conductor 11 in Example 4, and in the upper and left portions of the cross section of the coil conductor 11 in Example 5. rice field.

In Comparative Examples 1 to 3, as shown in FIG. 6, the coil conductor 11 has a substantially elliptical shape with a vertical cross section that is long in the left and right direction, and the continuous gap between the coil conductor 11 and the core 12 is the same as that in Examples 1 to 3. It was found that the adhesion was inferior to that of No. 5. Further, in a micrograph at a magnification of 50 times, cracks were generated on the left side of the cross section of the coil conductor 11 in Comparative Example 2, and on the left and right sides of the cross section of the coil conductor 11 in Comparative Example 2.

DESCRIPTION OF SYMBOLS 1... Coil conductor 2... Raw material powder 3... Mold 4... Insulator film 10... Inductor 11... Coil conductor 12... Core.

Claims (10)

An inductor comprising a core in which a coil conductor extending on a plane is embedded,
the coil conductor has an elliptical cross-sectional shape perpendicular to the extending direction with a major axis on the plane;
The core has a magnetic metal body with a filling rate of 80% by volume or more and less than 100% by volume,
An inductor, wherein the magnetic metal body bites into a total length of 75% or more and 100% or less of the circumference of the elliptical outer circumference in the cross-sectional shape of the coil conductor. 2. The inductor according to claim 1, wherein the magnetic metal body is made of Fe-based amorphous powder. 3. The inductor according to claim 1, wherein the coil conductor has a surface roughness Rz of 5 [mu]m or more and 40 [mu]m or less on the actual circumference of the cross-sectional shape. 4. The coil conductor according to any one of claims 1 to 3, wherein the total length of the actual perimeter of the cross-sectional shape of the coil conductor is 1.1 times or more and 2.5 times or less of the total length of the elliptical perimeter. inductor. 5. The method according to any one of claims 1 to 4, wherein an insulator having a thickness equal to or smaller than the average grain size of the magnetic metal body is present on the outer periphery of the elliptical shape of the cross-sectional shape of the coil conductor. inductor. 6. The elliptical cross-sectional shape in the vertical direction perpendicular to the direction in which the coil conductor extends has a major axis that is 1.3 to 2.0 times as large as a minor axis. or the inductor according to item 1. The filling rate of the magnetic metal bodies in the core positioned in the horizontal direction of the coil conductor is 0.8 to 1.0 times the filling rate of the magnetic metal bodies in the core positioned in the vertical direction of the coil conductor. 7. The inductor according to any one of claims 1 to 6, characterized by: a step of filling raw material powder containing magnetic metal powder and a binder into a mold in a state in which a coil conductor extending on a plane is embedded so that the plane is horizontal;
The metal mold filled with the raw material powder is pressurized in the vertical direction while being heated so that the cross-sectional shape of the coil conductor perpendicular to the extending direction is an ellipse having the major axis on the plane. A method of manufacturing an inductor, comprising: a step of deforming. The magnetic metal powder is made of Fe-based amorphous,
9. The method of manufacturing an inductor according to claim 8, wherein the heating temperature in the heating exceeds the softening temperature of the Fe-based amorphous. The surface of the coil conductor is coated with an insulating film,
10. The method of manufacturing an inductor according to claim 8, wherein the heating temperature in the heating exceeds the heat resistance temperature of the insulating film.

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