Coil component

Abstract

To improve electrical insulation between a conducting wire and a powder core without forming an insulating layer such as a glass layer on the surface of the powder core.SOLUTION: A coil component according to one or more embodiments of the present invention includes a powder core 10 that includes a first flange 12 having an inner surface 12a including a first surface 12a1 and a second surface 12a2, a second flange 13 facing the inner surface 12a of the first flange 12, and a winding core 11 that extends in an axial direction and connects the first flange 12 and the second flange 13, and consists of a plurality of metal magnetic particles which is bonded to each other with an insulating material such that the first surface 12a1 has lower smoothness than the second surface 12a2, and a conductive wire 25 wound around the winding core 11 so as to be in contact with the inner surface 12a on the first surface 12a1.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a coil component and a method for manufacturing a coil component. [Background technology]

[0002] A coil component of a wound type is known that includes a core and a conductor wound around the core. The core has a pair of flanges and a winding core that connects the pair of flanges. The surface of the conductor is covered with an insulating covering member.

[0003] JP 2011-014822 A (Patent Document 1) describes a wound coil component in which the periphery of a core is covered with a glass layer. The glass layer is formed by applying a glass paste, which is a mixture of glass powder and binder resin, to the surface of the core. In the coil component of Patent Document 1, the glass layer covering the surface of the core increases the mechanical strength of the core and also increases the insulation between the core and other members.

[0004] As described in JP 2013-045926 A (Patent Document 2), the core may be a molded body (called a "dust core") produced by compression molding metal magnetic particles. A coil component including a dust core exhibits better magnetic saturation characteristics than a coil component including a ferrite core. Cited Document 2 describes forming a glass coating on the surface of the dust core. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2011-014822 A [Patent Document 2] JP 2013-045926 A Summary of the Invention [Problem to be solved by the invention]

[0006] The conductor is wound around the core of the core using a winding machine such as a spindle winding machine or a flyer winding machine. When the conductor is wound around the core, the conductor may come into contact with the inner surface of the flange, damaging the coating material on the surface of the conductor, and the insulation of the conductor may decrease at the damaged area. Since the dust core has a smaller resistivity than the ferrite core, if the coating material of the conductor is partially damaged, current is likely to leak from the conductor to the dust core through the damaged area.

[0007] In the above Patent Documents 1 and 2, it is proposed to ensure the insulation of the core by covering the surface of the core with a glass layer. However, the glass slurry, which is the material of the glass layer, penetrates into the inside of the core through the grain boundaries of the ferrite grains contained in the core and the gaps between the metal magnetic particles, so that even if a part of the glass slurry penetrates into the inside of the core, the remainder remains on the surface of the core and can function as an insulating layer, so that the glass slurry is applied thickly to the surface of the core. In the case of a powder core, the amount of glass slurry that penetrates into the inside is large, so it is particularly difficult to adjust the amount of glass slurry applied. In order to ensure the insulation of the powder core, it is necessary to increase the amount of glass slurry applied, so that a thick glass layer is formed on the surface of the powder core, and the coil component becomes large by the thickness of the glass layer.

[0008] The object of the present invention is to solve or alleviate at least a part of the above-mentioned problems. One specific object of the present invention is to provide a novel coil component and a manufacturing method thereof capable of improving the electrical insulation between the conductor and the dust core. One more specific object of the present invention is to improve the electrical insulation between the conductor and the dust core without forming an insulating layer such as a glass layer on the surface of the dust core.

[0009] The object of the present invention other than the above will become clear throughout the entire description of the specification. The invention described in the claims may solve problems other than those grasped from the "Problem to be solved by the invention." [Means for solving the problem]

[0010] A coil component according to one embodiment of the present invention comprises a first flange having an inner surface including a first surface and a second surface, a second flange facing the inner surface of the first flange, and a winding core extending in an axial direction and connecting the first flange and the second flange, the coil component comprising a dust core made of a plurality of metal magnetic particles bonded together by an insulating material so that the first surface has a lower smoothness than the second surface, and a conductive wire wound around the winding core so that the first surface contacts the inner surface.

[0011] A method for manufacturing a coil component according to one embodiment of the present invention includes the steps of: filling a filling space defined by the inner surface of a die and the upper end surface of a lower punch with a mixed resin composition obtained by mixing a plurality of soft magnetic metal powders with a resin; moving an upper punch having an inclined surface inclined with respect to a uniaxial direction toward the lower punch along the uniaxial direction to compress the mixed resin composition, thereby obtaining a compression-molded body having a first surface extending along the inclined surface and a second surface extending along the uniaxial direction, wherein the first surface has lower smoothness than the second surface; heating the compression-molded body to obtain a dust core; and winding a conductor around the dust core so as to be in contact with the first surface.

[0012] A method for manufacturing a coil component according to one embodiment of the present invention includes the steps of: filling a cavity defined by the inner circumferential surface of a die and the upper end surface of a lower punch with a mixed resin composition obtained by mixing a plurality of soft magnetic metal powders with a resin; and compressing the mixed resin composition by moving an upper punch having a first pressure surface and a second pressure surface disposed closer to the lower punch than the first pressure surface along a uniaxial direction toward the lower punch. The upper punch has a first region compressed by the first pressure surface and having a first surface extending along the uniaxial direction, and a second region compressed by the second pressure surface and having a second surface extending along the uniaxial direction, and the first surface has a lower smoothness than the second surface. The method includes the steps of: heating the compression molded body to obtain a dust core; and winding a conductor around the dust core so as to be in contact with the first surface. Effect of the Invention

[0013] According to the invention disclosed in this specification, it is possible to improve the electrical insulation between the conductor and the dust core without forming an insulating layer such as a glass layer on the surface of the dust core. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a perspective view of a coil component according to an embodiment of the present invention. [Diagram 2] 2 is a longitudinal sectional view of the coil component of FIG. 1 mounted on a mounting board. [Diagram 3] 3 is a cross-sectional view of the coil component shown in FIG. 2 taken along line II. [Figure 4] 2 is a perspective view showing a dust core included in the coil component shown in FIG. 1. FIG. [Diagram 5] FIG. 5 is a cross-sectional view of the dust core shown in FIG. 4 along line II-II. [Figure 6] FIG. 5 is a schematic diagram showing a uniaxial press used to manufacture the dust core shown in FIG. 4. [Figure 7] FIG. 7 is a diagram showing a schematic view of an upper punch of the uniaxial press machine of FIG. 6. [Figure 8a] 5 is a schematic diagram for explaining a method for producing the dust core shown in FIG. 4. FIG. [Figure 8b] 5 is a schematic diagram for explaining a method for producing the dust core shown in FIG. 4. FIG. [Figure 8c] 5 is a schematic diagram for explaining a method for producing the dust core shown in FIG. 4. FIG. [Figure 9a] FIG. 5 is a schematic diagram illustrating the microstructure of a second surface of the dust core of FIG. 4. [Figure 9b] FIG. 5 is a schematic diagram illustrating the microstructure of a first surface of the dust core of FIG. 4. [Figure 10] FIG. 4 is a cross-sectional view of a coil component according to another embodiment of the present invention. [Figure 11] 11 is a perspective view showing a dust core included in the coil part shown in FIG. 10. FIG. [Figure 12] 12 is a cross-sectional view of the dust core shown in FIG. 11 along line VV. [Figure 13] FIG. 12 is a schematic diagram showing a mold used to manufacture the dust core shown in FIG. 11 . [Figure 14a] 12A to 12C are schematic diagrams for explaining a method for producing the dust core shown in FIG. 11. [Figure 14b] 12A to 12C are schematic diagrams for explaining a method for producing the dust core shown in FIG. 11. [Figure 14c] 12A to 12C are schematic diagrams for explaining a method for producing the dust core shown in FIG. 11. [Figure 15] FIG. 4 is a cross-sectional view of a coil component according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Various embodiments of the present invention will be described below with reference to the drawings as appropriate. Note that components common to multiple drawings are given the same reference numerals throughout the multiple drawings. Please note that the drawings are not necessarily drawn to scale for the sake of convenience. The embodiments of the present invention described below do not limit the invention according to the claims. Elements described in the following embodiments are not necessarily essential to the solution of the invention.

[0016] 1 to 5 show a coil component 1 according to an embodiment of the present invention. The coil component 1 is, for example, an inductor used to remove noise in an electronic circuit. The coil component 1 may be a power inductor incorporated in a power supply line, or an inductor used in a signal line.

[0017] First, an overview of a coil component 1 will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a perspective view of a coil component 1 according to an embodiment of the present invention, and Fig. 2 is a vertical cross-sectional view of the coil component 1 mounted on a mounting substrate 2a. The mounting substrate 2a is not shown in Fig. 1.

[0018] 1, the coil component 1 includes a dust core 10 and a conductive wire 25 provided on the dust core 10. Hereinafter, the dust core 10 may be simply referred to as the core 10.

[0019] The drawings accompanying this specification show a W-axis, an L-axis, and a Z-axis that are perpendicular to each other. In this specification, unless otherwise understood in the context, the "length" direction, the "width" direction, and the "thickness" direction of the coil device 1 are respectively the "L-axis" direction, the "W-axis" direction, and the "T-axis" direction in Fig. 1. In this specification, the orientation and arrangement of the components of the coil device 1 may be described based on the L-axis direction, the W-axis direction, and the Z-axis direction.

[0020] The core 10 is made of a magnetic material containing metal magnetic particles, for example, by compression molding. The core 10 contains a large number of metal magnetic particles. In one embodiment, adjacent metal magnetic particles in the core 10 are bonded to each other via an insulating material. The insulating material is, for example, an insulating film covering the surface of the metal magnetic particle. The insulating film covering the surface of the metal magnetic particle contains an oxide of an element contained in the metal magnetic particle. In another embodiment, the insulating material between adjacent metal magnetic particles in the core 10 is an insulating binder made of a thermosetting resin with excellent insulating properties, such as an epoxy resin. The average particle size of the metal magnetic particles contained in the core 10 is, for example, 1 to 20 μm. The average particle size of the metal magnetic particles can be the average particle size (median diameter (D50)) calculated from a particle size distribution measured on a volume basis.

[0021] The core 10 has a winding core 11 extending along the axial direction, a plate-shaped first flange 12 provided at one end of the winding core 11, and a plate-shaped second flange 13 provided at the other end of the winding core 11. The winding core 11 connects the first flange 12 and the second flange 13. In the illustrated embodiment, the winding core 11 extends along the T-axis direction, so the axial direction coincides with the T-axis direction.

[0022] In the illustrated embodiment, the winding core 11 has a rectangular prism shape. The winding core 11 may have any shape suitable for winding the conductive wire 25. For example, the winding core 11 may have a polygonal prism shape such as a triangular prism shape, a pentagonal prism shape, or a hexagonal prism shape, a cylindrical shape, an elliptical cylindrical shape, or a truncated cone shape, in addition to a rectangular prism shape.

[0023] The first flange 12 has an inner surface 12a and an outer surface 12b facing the inner surface 12a. The second flange 13 has an inner surface 13a and an outer surface 13b facing the inner surface 13a. The inner surface 12a of the first flange 12 faces the inner surface 13a of the second flange 13.

[0024] In the illustrated embodiment, the outer surface 12b of the first flange 12 is a flat surface formed flat. The outer surface 13b of the second flange 13 is provided with a first recess 14a and a second recess 14b extending along the W-axis direction. The first recess 14a is spaced apart from the second recess 14b in the L-axis direction. An external electrode 21 made of a conductive material is provided on the surface of the first recess 14a, and an external electrode 22 made of a conductive material is provided on the surface of the second recess 14b. Each of the external electrodes 21 and 22 may include a base layer made of a metal material such as copper, silver, palladium, or a silver-palladium alloy, and a plating layer provided on the base layer. The plating layer may have a two-layer structure of a nickel plating layer and a tin plating layer.

[0025] A conductor 25 is wound around the winding core 11. The conductor 25 is formed by covering the periphery of a metal wire made of a metal material with excellent conductivity with an insulating coating. For example, one or more metals selected from Cu, Al, Ni, and Ag, or an alloy containing any of these metals, may be used as the metal material for the conductor 25. The insulating coating provided around the conductor is made of, for example, polyesterimide, polyamide, or other insulating material with excellent insulation properties. One end 25a of the conductor 25 is drawn out into the first recess 14a, and the other end 25b of the conductor 25 is drawn out into the second recess 14b. The conductor 25 may be provided such that one end 25a contacts the external electrode 21 provided on the bottom surface of the first recess 14a, and the other end 25b contacts the external electrode 22 provided on the bottom surface of the second recess 14b. The portion of the conductor 25 that is arranged around the winding core 11 is sometimes called a winding portion 25c. In the illustrated embodiment, the cross-sectional shape of the conductor 25 is circular. The cross-sectional shape of the conductor 25 is not limited to a circle, and may be an ellipse, an oval, a rectangle, or a square.

[0026] As shown in Fig. 2, the coil component 1 may be mounted on a mounting board 2a. The coil component 1 is joined to a land 3a and a land 3b of the mounting board 2a by a solder portion 30a provided on the core 10 so as to cover one end 25a of the conductor 25 and a solder portion 30b provided on the core 10 so as to cover the other end 25b of the conductor 25, respectively. A gap G exists between the land 3a and the land 3b. The conductor 25 may be electrically connected to the land 3a via the solder portion 30a, or may be in direct contact with the land 3a. Similarly, the conductor 25 may be electrically connected to the land 3b via the solder portion 30b, or may be in direct contact with the land 3b.

[0027] The solder portion 30a can be produced by heating the solder paste filled in the first recess 14a to generate molten solder, which spreads over the first recess 14a, and solidifying the molten solder that has spread over the first recess 14a. In one or more embodiments of the present invention, the insulating coating covering the conductor 25 is removed from the conductor 25 before filling the first recess 14a with solder. The insulating coating covering the conductor 25 may be thermally decomposed by contact with the molten solder generated by melting the solder portion 30a during mounting, and may be removed from the conductor 25 by this thermal decomposition. The solder paste is made of any solder material. For example, a lead-free alloy material specified in JIS Z 3282 may be used as the solder material. The solder paste may be applied to the first recess 14a by, for example, a stencil printing method. The solder portion 30a may be formed by immersing the core 10 in a solder bath. The solder portion 30a may be formed by fitting a compact of solder material obtained by molding the solder material using a mold into the first recess 14a together with one end 25a of the conductor 25, and heating the compact of solder material fitted into the first recess 14a. The specific method of forming the solder portion 30a is not limited to those explicitly disclosed in this specification. The solder portion 30b is provided in the second recess 14b in the same manner as the solder portion 30a so as to be electrically connected to the other end 25b of the conductor 25.

[0028] As described above, the coil component 1 is disposed so that the outer surface 13b of the second flange 13 of the core 10 faces the mounting board 2a, and is mounted on the mounting board 2a via the external electrodes 21, 22 and the solder parts 30a, 30b provided on this outer surface 13b. Therefore, the outer surface 13b of the second flange 13 becomes the mounting surface of the coil component 1.

[0029] Next, the core 10 will be described with further reference to Fig. 3 to Fig. 5. Fig. 3 is a cross-sectional view of the coil device 1 in Fig. 2 taken along line II, Fig. 4 is a perspective view showing the core 10 included in the coil device 1, and Fig. 5 is a cross-sectional view of the core 10 taken along line II-II.

[0030] As shown in Figures 3 to 5, the inner surface 12a of the first flange 12 is divided into a first surface 12a1 and a second surface 12a2. The first surface 12a1 has a lower smoothness than the second surface 12a2. In other words, the first surface 12a1 is rougher than the second surface 12a2. In this specification, the smoothness of the surface of the core 10 is defined as the arithmetic mean of the surface of the core 10. height It is represented by Sa. Average height Sa is calculated using a measuring device that complies with ISO25178. Average height Sa can be measured using a shape analysis laser microscope (VK-X250) manufactured by Keyence Corporation. height is the first Sa, and the arithmetic mean of the second surface 12a2 is height Assuming that the second Sa is the first Sa, the first Sa is larger than the second Sa. In one embodiment, the first Sa is at least twice as large as the second Sa. In one embodiment, the first Sa is two to three times the value of the second Sa.

[0031] In one embodiment, the outer surface 12b of the first flange 12 has a lower smoothness than the second surface 12a2 of the inner surface 12a. In this case, the arithmetic mean of the outer surface 12b height The arithmetic mean of the outer surface 12b is the same as that of the second surface 12a2. height The third Sa is the arithmetic mean of the first surface 12a1 of the inner surface 12a. height It may be smaller than the first Sa.

[0032] In one embodiment, the arithmetic mean of the first surface 12a1 height The first Sa is equal to or greater than 1 / 20 of the average grain size of the metal magnetic grains contained in the core 10. The arithmetic mean of the second surface 12a2 height Arithmetic mean of second Sa and outer surface 12b height The third Sa is smaller than 1 / 20 of the average grain size of the metal magnetic grains contained in the core 10. height The first Sa is, for example, 0.3 μm or more and 1 μm or less. heightThe second Sa is, for example, 0.1 μm or more and less than 0.3 μm. height The arithmetic mean of the first surface 12a1 is, for example, 0.2 μm or more and less than 0.6 μm. height The first Sa is the arithmetic mean of the second surface 12a2. height Since the surface resistance value of the first surface 12a1 per unit length is greater than the surface resistance value of the second surface 12a2 per unit length, the surface resistance value of the first surface 12a1 per unit length is greater than the surface resistance value of the second surface 12a2 per unit length. The surface resistance value of the surface of the core 10 can be measured using a commercially available contact-type resistance measuring device in accordance with JIS C-2139-3-2. The surface resistance value of the surface of the core 10 can be measured using a super insulation meter (SM8203) manufactured by Toa DKK. Similarly, the arithmetic mean of the outer surface 12b height The third Sa is the arithmetic mean of the second surface 12a2. height Since the surface resistance of the first surface 12a1 is greater than the second Sa, the surface resistance of the outer surface 12b per unit length is greater than the surface resistance of the second surface 12a2 per unit length. The surface resistance of the first surface 12a1 can be 1000 MΩ / cm or more and 10000 MΩ / cm or less. The surface resistance of the second surface 12a2 can be 100 MΩ / cm or more and less than 1000 MΩ / cm. The surface resistance of the outer surface 12b can be 500 MΩ / cm or more and less than 5000 MΩ / cm.

[0033] The inner surface 13a of the second flange 13 is divided into a first surface 13a1 and a second surface 13a2, similar to the inner surface 12a of the first flange 12. The smoothness of the first surface 13a1 is lower than that of the second surface 13a2. The first surface 13a1 of the inner surface 13a of the second flange 13 is provided at a position facing the first surface 12a1 of the inner surface 12a of the first flange 12, and the second surface 13a2 of the inner surface 13a of the second flange 13 is provided at a position facing the second surface 12a2 of the inner surface 12a of the first flange 12. In one embodiment, the outer surface 13b of the second flange 13 has a lower smoothness than the second surface 13a2 of the inner surface 13a. The arithmetic mean of the first surface 13a1 height is the arithmetic mean of the second surface 13a2 heightSince the surface resistance of the first surface 13a1 per unit length is greater than the surface resistance of the second surface 13a2 per unit length, the arithmetic mean of the outer surface 13b is height is the arithmetic mean of the second surface 13a2 height , the surface resistance value per unit length of the outer surface 13b is greater than the surface resistance value per unit length of the second surface 13a2.

[0034] For simplicity of explanation, the present specification will mainly discuss the first flange 12, but the discussion of the first flange 12 also applies to the second flange 13 as far as possible.

[0035] As shown in FIG. 3 and FIG. 4, the first surface 12a1 is disposed at a position closer to the second flange 13 than the second surface 12a2 in the T-axis direction. The first surface 12a1 protrudes from the inner surface 12a of the first flange 12 toward the second flange 13. In the illustrated embodiment, the second surface 12a2 extends in a direction perpendicular to the axial direction (T-axis direction). In other words, the second surface 12a2 extends parallel to the LW plane perpendicular to the axial direction. In the illustrated embodiment, the first surface 12a1 is inclined with respect to the second surface 12a2. As shown in the drawings, the first surface 12a1 may be inclined with respect to the second surface 12a2 so as to be farthest from the second surface 12a2 at the connection position with the winding core 11. Both the first surface 12a1 and the second surface 12a2 are flat surfaces.

[0036] Similarly, in the second flange 13, the first surface 13a1 is disposed at a position closer to the first flange 12 than the second surface 13a2 in the T-axis direction. The first surface 13a1 protrudes from the inner surface 13a of the second flange 13 toward the first flange 12. In the illustrated embodiment, the second surface 13a2 extends in a direction perpendicular to the axial direction (T-axis direction). In other words, the second surface 13a2 extends parallel to the LW plane perpendicular to the axial direction. In the illustrated embodiment, the first surface 13a1 is inclined with respect to the second surface 13a2. As illustrated, the first surface 13a1 may be inclined with respect to the second surface 13a2 so as to be farthest from the second surface 13a2 at the connection position with the winding core 11. Both the first surface 13a1 and the second surface 13a2 are flat surfaces.

[0037] As shown in FIG. 5, the inner surface 12a of the first flange 12 is divided into a first region R1 on the positive side of the W axis direction relative to the winding core 11, a second region R2 on the negative side of the W axis direction relative to the winding core 11, a third region R3 on the positive side of the L axis direction relative to the winding core 11, and a fourth region R4 on the negative side of the L axis direction relative to the winding core 11, when viewed from the axial direction (T axis direction). Of these regions, the first region R1 and the second region R2 constitute the first surface 12a1, and the third region R3 and the fourth region R4 constitute the second surface 12a2. In other words, the first surface 12a1 is divided into the first region R1 and the second region R2, and the second surface 12a2 is divided into the third region R3 and the fourth region R4. The region R1 is in contact with the third region R3 and the fourth region R4 in the L axis direction. Similarly, the region R2 is in contact with the third region R3 and the fourth region R4 in the L-axis direction.

[0038] The outer peripheral surface of the winding core 11 is defined by a first peripheral surface 11a, a second peripheral surface 11b facing the first peripheral surface 11a, a third peripheral surface 11c connecting the first peripheral surface 11a and the second peripheral surface 11b, and a fourth peripheral surface 11d facing the third peripheral surface 11c. A first region R1 of the first surface 12a1 of the first flange 12 contacts the first peripheral surface 11a of the winding core 11, and a second region R2 contacts the second peripheral surface 11b of the winding core 11. In the illustrated embodiment, the dimension (= a) of the first peripheral surface 11a of the winding core 11 in the L-axis direction is equal to the dimension (= a) of the second peripheral surface 11b in the L-axis direction. In one embodiment, the dimension in the L axis direction of the first surface 12a1 of the first flange 12 is equal to the dimension in the L axis direction of the first circumferential surface 11a of the winding core 11 and the dimension in the L axis direction of the second circumferential surface 11b of the winding core 11. Thus, the first surface 12a1 is in contact with the winding core over the length 2a.

[0039] In one embodiment, the third region R3 of the second surface 12a2 of the first flange 12 contacts the third circumferential surface 11c of the winding core 11, and the fourth region R4 contacts the fourth circumferential surface 11d of the winding core 11. In the illustrated embodiment, the dimension (= b) of the third circumferential surface 11c of the winding core 11 in the W-axis direction is equal to the dimension (= b) of the fourth circumferential surface 11d in the W-axis direction. Thus, the second surface 12a2 contacts the winding core over a length 2b.

[0040] In one embodiment, the area of ​​the second surface 12a2 of the first flange 12 (i.e., the sum of the areas of the regions R3 and R4) is greater than the area of ​​the first surface 12a1 (i.e., the sum of the areas of the regions R1 and R2).

[0041] When manufacturing the coil component 1, the core 10 is molded from a magnetic material containing metallic magnetic particles by a compression molding method, and then the conductive wire 25 is wound around the winding core 11 of the core 10. The conductive wire 25 is wound around the winding core 11 using a commercially available spindle-type winding machine, a commercially available flyer-type winding machine, or any other known winding machine.

[0042] 3, in the core 10, the first surface 12a1 of the inner surface 12a of the first flange 12 protrudes toward the second flange 13, so that the conductor 25 contacts the first surface 12a1 of the inner surface 12a of the first flange 12. In one embodiment, the second surface 12a2 is located further back than the first surface 12a1 in the T-axis direction, so that the conductor 25 does not contact the second surface 12a2. Therefore, only the first surface 12a1 of the inner surface 12a of the first flange 12 comes into contact with the conductor 25.

[0043] Similarly, in the core 10, the first surface 12a1 of the inner surface 12a of the first flange 12 protrudes toward the second flange 13, so that the conductor 25 contacts the inner surface 13a of the second flange 13 at the first surface 13a1. In one embodiment, the second surface 13a2 is located further back than the first surface 13a1 in the T-axis direction, so that the conductor 25 does not contact the second surface 13a2. Therefore, only the first surface 13a1 of the inner surface 13a of the second flange 13 comes into contact with the conductor 25.

[0044] When the conductor 25 is wound around the winding core 11 by the winding machine, both ends of the conductor are pulled by the nozzle of the winding machine, so that the conductor is under tension. Therefore, if the conductor 25 comes into contact with the inner surface 12a of the first flange 12 or the inner surface 13a of the second flange 13 when winding the conductor 25 around the winding core 11, the insulating coating on the surface of the conductor 25 may be damaged. The conductor 25 comes into contact with the inner surface 12a of the first flange 12 only on the first surface 12a1. As described above, first surface 12a1 has a higher surface resistance than second surface 12a2, so even if the covering material of conductor wire 25 is damaged due to friction with inner surface 12a of first flange 12 when winding conductor wire 25 around winding core 11, the damaged portion of conductor wire 25 comes into contact with inner surface 12a at first surface 12a1, which has a higher surface resistance, and therefore current leakage through the damaged portion of the covering material of conductor wire 25 between conductor wire 25 and first flange 12 can be suppressed. Similarly, conductor wire 25 comes into contact with inner surface 13a of second flange 13 only at first surface 13a1, so current leakage through the damaged portion of the covering material of conductor wire 25 between conductor wire 25 and second flange 13 can be suppressed.

[0045] The core 10 can be produced by a uniaxial press method. Fig. 6 is a schematic diagram of a uniaxial press machine for producing the core 10, and Fig. 7 shows an upper punch 52 of the uniaxial press machine. As shown in the figure, the uniaxial press machine 50 includes a die 51 having a through hole, an upper punch 52, and a lower punch 53.

[0046] As shown in Fig. 7, the upper punch 52 has a flat first pressing surface 52a, a flat second pressing surface 52b, a first inclined surface 52c1 provided on a protruding portion 52c protruding downward, a second inclined surface 52c2 provided on the protruding portion 52c, and a flat third pressing surface 52c3 connecting the first inclined surface 52c1 and the second inclined surface 52c2. The first inclined surface 52c1 forms an angle of more than 1° with respect to the stroke direction (the up-down direction of the paper in Figs. 8a to 8c described later). Similarly, the second inclined surface 52c2 forms an angle of more than 1° with respect to the stroke direction. The lower punch 53 has the same shape as the upper punch 52. Specifically, the lower punch 53 has a flat first pressing surface 53a, a flat second pressing surface 53b, a first inclined surface 53c1 provided on the protruding portion 53c protruding upward, a second inclined surface 53c2 provided on the protruding portion 52c, and a flat third pressing surface 53c3 connecting the first inclined surface 53c1 and the second inclined surface 53c2. The lower punch 53 is installed in the through hole of the die 51 so that the up-down direction is opposite to that of the upper punch 52. The upper punch 52 and the lower punch 53 are movable in the stroke direction. The stroke direction of the upper punch 52 and the lower punch 53 is the up-down direction of the paper.

[0047] A method for manufacturing the core 10 will be described with reference to Figures 8a to 8c. Figures 8a to 8c are schematic cross-sectional views of a uniaxial press machine 50 taken along line III-III in Figure 6. First, as shown in Figure 8a, a magnetic material M is filled into a filling space defined by the inner peripheral surface of a die 51 and the upper end surface of a lower punch 53. The magnetic material M is a mixed resin composition obtained by mixing soft magnetic metal powder and resin.

[0048] Next, the magnetic material M filled in the filling space is pressed by the lower punch 53 and the upper punch 52. Specifically, the upper punch 52 is lowered to the position shown in FIG. 8b, and the magnetic material M is pressed by the lower punch 53, the upper punch 52, and the die 51. Then, the upper punch 52 is raised to obtain a molded body 60 having a shape corresponding to the core 10, as shown in FIG. 8c. The molded body 60 is a molded body containing a plurality of metal magnetic particles. The molded body 60 has a winding core portion 61 corresponding to the winding core 11, a first flange portion 62 corresponding to the first flange 12, and a second flange portion 63 corresponding to the second flange 13. The first flange portion 62 has an inclined surface 62a1 corresponding to the first inclined surface 52c1 of the upper punch 52 and the first inclined surface 53c1 of the lower punch 53, and a flat surface 62a2 extending along the stroke direction. The second flange portion 63 has an inclined surface 63a1 corresponding to the second inclined surface 52c2 of the upper punch 52 and the second inclined surface 53c2 of the lower punch 53, and a flat surface 63a2 extending along the stroke direction.

[0049] After the molded body 60 is removed from the uniaxial press 50, the molded body 60 is heated to obtain the core 10. Through this heat treatment, the winding core portion 61 of the molded body 60 becomes the winding core 11, the first flange portion 62 becomes the first flange 12, and the second flange portion 63 becomes the second flange 13. The heat treatment of the molded body 60 is performed, for example, at 600°C to 850°C for 30 minutes to 240 minutes.

[0050] In the above manufacturing process, when the upper punch 52 is raised after the magnetic material M is pressed, a frictional force acts on the flat surface 62a2 of the molded body 60 from the molding surface extending along the stroke direction of the upper punch 52. Due to this frictional force, the metal magnetic particles exposed from the flat surface 62a2 among the multiple metal magnetic particles contained in the molded body 60 are deformed in the stroke direction. As a result, as shown in FIG. 9a, in the core 10, the metal magnetic particles 31 exposed from the second surface 12a2 of the first flange 12 are deformed more along the stroke direction than the metal magnetic particles 31 inside the core 10. In this way, due to the frictional force when the upper punch 52 is raised after pressing, the metal magnetic particles 31 exposed from the flat surface 62a2 of the molded body 60 are deformed along the stroke direction, and as a result, the unevenness caused by the shape of the metal magnetic particles 31 on the flat surface 62a2 is reduced. For this reason, the flat surface 62a2 of the molded body 60, and therefore the second surface 12a2 of the first flange 12 of the core 10, have high smoothness. For the same reason, the second surface 13a2 of the second flange 13 of the core 10 also has high smoothness.

[0051] On the other hand, since the inclined surface 62a1 is inclined with respect to the stroke direction, when the upper punch 52 is raised, the frictional force from the upper punch 52 does not act on the inclined surface 62a1. Therefore, when the upper punch 52 is raised, the unevenness of the metal magnetic particles is maintained on the inclined surface 62a1. As a result, as shown in FIG. 9b, in the core 10, the metal magnetic particles 31 exposed from the first surface 12a1 of the first flange 12 are suppressed from being deformed compared to the metal magnetic particles 31 exposed from the second surface 12a2. For this reason, the smoothness of the inclined surface 62a1 in the molded body 60, and therefore the smoothness of the first surface 12a1 in the first flange 12 of the core 10, is lower than that of the second surface 12a2. For the same reason, the smoothness of the first surface 13a1 in the second flange 13 of the core 10 is also lower than that of the second surface 13a2.

[0052] Next, a coil device 101 according to another embodiment will be described with reference to Fig. 10 to Fig. 12. The coil device 101 differs from the coil device 1 in that it includes a core 110 instead of the core 10. The coil device 1 and the coil device 101 have common features other than the shape of the core, so the following description will mainly focus on the core 110, and a description of the common features will be omitted.

[0053] As shown in Figs. 10 and 11, the first flange 12 of the core 110 has an inner surface 12a and an outer surface 12b. The inner surface 12a of the first flange 12 is divided into a first surface 112a1 and a second surface 12a2. Unlike the first surface 12a1, the first surface 112a1 extends parallel to the second surface 12a2. The first surface 112a1 has a lower smoothness than the second surface 12a2. The description regarding the smoothness of the first surface 12a1 of the coil device 1 also applies to the smoothness of the first surface 112a1.

[0054] Fig. 12 is a cross-sectional view taken along line VV of core 110. As shown in Fig. 12, the arrangement of first surfaces 112a1 as viewed from the T-axis direction is similar to the arrangement of first surfaces 12a1.

[0055] The second flange 13 of the core 110 has an inner surface 13a and an outer surface 13b. The inner surface 13a of the second flange 13 is divided into a first surface 113a1 and a second surface 13a2. Unlike the first surface 13a1, the first surface 113a1 extends parallel to the second surface 13a2. The first surface 113a1 has a lower smoothness than the second surface 13a2. The description regarding the smoothness of the first surface 13a1 of the coil component 1 also applies to the smoothness of the first surface 113a1.

[0056] The core 110 is produced by the uniaxial press method, similarly to the core 10. A method for producing the core 110 will be described with reference to FIG. 13 and FIGS. 4a to 14c. The core 110 can be produced by using a uniaxial press machine 50. However, since the core 110 has a different shape from the core 10, an upper punch 152 is used instead of the upper punch 52, and a lower punch 153 is used instead of the lower punch 53. FIG. 13 shows a schematic diagram of the upper punch 152 used in the uniaxial press machine for producing the core 110. Also, FIGS. 14a to 14c show a schematic diagram of a cross section of the uniaxial press machine used for producing the core 110, taken along line IV-IV in FIG. 6.

[0057] 13, the upper punch 152 has a plate-shaped first portion 152a, a plate-shaped second portion 152b, and a protruding portion 152c protruding downward from a connection portion between the first portion 152a and the second portion 152b. The first portion 152a has a flat first pressure surface 152a1, and flat second and third pressure surfaces 152a2 and 152a3 located below the first pressure surface 152a1. The second portion 152b may be configured to have substantially the same shape as the first portion 152a. The protruding portion 152c has a flat fourth pressure surface 152c1.

[0058] The lower punch 153 has the same shape as the upper punch 152. Specifically, the lower punch 153 includes a first pressing surface 153a1 provided at a position facing the first pressing surface 152a1, a second pressing surface 153a2 provided at a position facing the second pressing surface 152a2, and a third pressing surface 153a3 provided at a position facing the third pressing surface 152a3. The lower punch 153 has a fourth pressing surface 153c1 provided on a protruding portion protruding upward so as to face the fourth pressing surface 152c1.

[0059] To manufacture the core 110, first, as shown in Fig. 14a, a magnetic material M is filled into a filling space defined by the inner peripheral surface of the die 151 and the upper end surface of the lower punch 153. The magnetic material M is a mixed resin composition obtained by mixing soft magnetic metal powder and resin.

[0060] Next, the magnetic material M filled in the filling space is pressed by the lower punch 153 and the upper punch 152. Specifically, the upper punch 152 is lowered to the position shown in FIG. 14b, and the magnetic material M is pressed by the lower punch 153, the upper punch 152, and the die 151. Then, the upper punch 152 is raised to obtain a molded body 160 having a shape corresponding to the core 110, as shown in FIG. 14c. The molded body 160 is a molded body containing a plurality of metal magnetic particles. As shown in FIG. 14c, the molded body 160 has a winding core portion 61 corresponding to the winding core 11, a first flange portion 162 corresponding to the first flange 12, and a second flange portion corresponding to the second flange 13. Although the second flange portion is not shown, the second flange portion has the same shape as the first flange portion from the viewpoint of FIG. 14c. The molded body 160 is subjected to a heat treatment to obtain the core 110.

[0061] The molded body 160 is divided into a plurality of regions with different compression amounts. Specifically, the molded body 160 is divided into a first region 160a compressed between a first pressure surface 152a1 of the upper punch 152 and a first pressure surface 153a1 of the lower punch 153, a second region 160b compressed between a second pressure surface 152a2 of the upper punch 152 and a second pressure surface 153a2 of the lower punch 153, and a third region 160c compressed between a third pressure surface 152a3 of the upper punch 152 and a third pressure surface 153a3 of the lower punch 153. Since the second region 160b and the third region 160c are compressed between the second pressure surface 152a2 and the third pressure surface 152a3 of the upper punch 152, which are closer to the lower punch 153 than the first pressure surface 152a1, and the second pressure surface 153a2 and the third pressure surface 153a3 of the lower punch 153, which are closer to the upper punch 152 than the first pressure surface 153a1, the compression amount of the second region 160b and the third region 160c is larger than the compression amount of the first region 160a compressed between the first pressure surface 152a1 of the upper punch 152 and the first pressure surface 153a1 of the lower punch 153. Therefore, the filling rate of the metal magnetic particles in the second region 160b and the third region 160c is larger than the filling rate of the metal magnetic particles in the first region 160a. Moreover, the metal magnetic particles contained in the second region 160b and the third region 160c are deformed more than the metal magnetic particles contained in the first region 160a. Therefore, the flat surface 162a2 constituting the surface of the second region 160b and the third region 160c of the molded body 160 has a higher smoothness than the flat surface 162a1 constituting the surface of the first region 160a. Therefore, the smoothness of the flat surface 162a1 in the molded body 160 is lower than the smoothness of the flat surface 162a2 in the molded body 160. Therefore, in the core 110 obtained by subjecting the molded body 160 to a heat treatment, the smoothness of the first surface 112a1 in the first flange 12 is lower than the smoothness of the second surface 12a2. For the same reason, the smoothness of the first surface 113a1 in the second flange 13 of the core 110 is also lower than the smoothness of the second surface 13a2.

[0062] Next, a coil device 201 according to another embodiment will be described with reference to Fig. 15. The coil device 201 differs from the coil device 1 in that it includes an exterior part 40. A description of the features of the coil device 201 that are common to the coil device 1 will be omitted.

[0063] The exterior part 40 is formed by filling a resin composition containing an insulating resin between the first flange 12 and the second flange 13. A resin material having excellent insulating properties, such as an epoxy resin, can be used as the resin material for the exterior part 40. The exterior part 40 is filled in a part or the whole of the region between the first flange 12 and the second flange 13. The exterior part 40 is provided so as to cover the conductive wire 25. The exterior part 40 may contain a filler. As the filler, a magnetic material or a non-magnetic material can be used. By using ferrite powder, metal magnetic particles, alumina particles, or silica particles as the filler, the linear expansion coefficient of the exterior part 40 can be reduced and the mechanical strength can be increased.

[0064] When the resin composition that is the material of the exterior portion 40 is filled between the first flange 12 and the second flange 13, the first surface 12a1 of the first flange 12 is rougher than the second surface 12a2, and the first surface 13a1 of the second flange 13 is rougher than the second surface 13a2, so that the resin composition easily permeates from the first surface 12a1 and the first surface 13a1 into the inside of the core 10. In the coil component 201, the area of ​​the first surface 12a1 of the first flange 12 is smaller than the area of ​​the second surface 12a2, and the area of ​​the first surface 13a1 of the second flange 13 is smaller than the area of ​​the second surface 13a2, so that the permeation of the resin composition into the core 10 can be suppressed. In this way, by making the area of ​​first surface 12a1 smaller than the area of ​​second surface 12a2 and by making the area of ​​first surface 13a1 smaller than the area of ​​second surface 13a2, the adhesion between the exterior portion 40 and the inner surface 12a of the first flange 12 and the inner surface 13a of the second flange 13 can be improved.

[0065] Next, the effects of the above embodiment will be described. According to one embodiment of the present invention, the inner surface 12a of the first flange 12 has a first surface 12a1 and a second surface 12a2, and the first surface 12a1 is configured to have a lower smoothness than the second surface 12a2. The conductor 25 is wound around the winding core 11 so that the first surface 12a1 contacts the inner surface 12a of the first flange 12. As described above, the first surface 12a1 has a higher surface resistance than the second surface 12a2. Therefore, even if the covering member of the conductor 25 is damaged by friction with the inner surface 12a of the first flange 12 when the conductor 25 is wound around the winding core 11, the damaged portion of the conductor 25 contacts the inner surface 12a at the first surface 12a1, which has a higher surface resistance, so that leakage of current through the damaged portion of the covering member of the conductor 25 between the conductor 25 and the first flange 12 can be suppressed.

[0066] According to one embodiment of the present invention, the first surface 12a1 of the inner side surface 12a of the first flange 12 is disposed at a position closer to the second flange 13 than the second surface 12a2 in the T-axis direction. Therefore, the conductive wire 25 wound so as to be in contact with the first surface 12a1 can be prevented from contacting the second surface 12a2.

[0067] According to one embodiment of the present invention, winding core 11 is in contact with first surface 12a1 over length a, and in contact with second surface 12a2 over length b that is shorter than length a. This allows conductor wire 25 wound around winding core 11 to be supported by first surface 12a1. This makes it possible to prevent contact between conductor wire 25 and second surface 12a2.

[0068] According to one embodiment of the present invention, the area of ​​first surface 12a1 is smaller than the area of ​​second surface 12a2, and the area of ​​first surface 13a1 is smaller than the area of ​​second surface 13a2, so that the adhesion between the exterior portion 40 and the inner surface 12a of the first flange 12 and the inner surface 13a of the second flange 13 can be improved.

[0069] The dimensions, materials, and arrangement of each component described in this specification are not limited to those explicitly described in the embodiments, and each component can be modified to have any dimensions, materials, and arrangement that can be included in the scope of the present invention. In addition, components not explicitly described in this specification can be added to the described embodiments, and some of the components described in each embodiment can be omitted. For example, the first surface 13a1 can be omitted in the second flange 13. In this case, the inner surface 13a of the second flange 13 becomes a flat surface having a substantially uniform smoothness. When the conductive wire 25 is arranged biasedly near the first flange 12 and does not contact the second flange 13, the second flange 13 does not need to have the first surface 13a1.

[0070] Some of the steps included in the manufacturing method described in this specification may be omitted as appropriate, provided that no contradiction occurs. In the manufacturing method described in this specification, steps not explicitly described in this specification may be performed as necessary. Some of the steps included in the manufacturing method described in this specification may be performed in a different order as needed, provided that the order does not deviate from the spirit of the present invention. Some of the steps included in the manufacturing method described in this specification may be performed simultaneously or in parallel, if possible.

[0071] The designations "first," "second," "third," and the like in this specification are given to identify components, and do not necessarily limit the number, order, or content. Furthermore, numbers for identifying components are used in different contexts, and a number used in one context does not necessarily indicate the same configuration in another context. Furthermore, a component identified by a certain number does not prevent the component from also having the function of a component identified by another number.

[0072] This specification also discloses the following techniques. [1] Inside including the first and second surfaces of a first flange having a surface; ofa second flange facing the first flange and a core extending in an axial direction and connecting the first flange and the second flange; and a dust core made of a plurality of metal magnetic particles bonded to each other by an insulating material such that the first surface has a lower smoothness than the second surface; The inner side of the first surface of a conductive wire wound around the winding core so as to contact a surface of the winding core; A coil component comprising: [2] The first surface is disposed at a position closer to the second flange than the second surface in the axial direction. [1] A coil component according to the present invention. [3] The conductive wire does not contact the second surface. A coil component according to [1] or [2]. [4] The winding core is in contact with the first surface over a first length and in contact with the second surface over a second length that is shorter than the first length. A coil component according to any one of [1] to [3]. [5] The first surface is divided into a first region and a second region, and the first region is disposed on the opposite side of the winding core from the second region. A coil component according to any one of [1] to [4]. [6] A first area representing an area of ​​the first surface is smaller than a second area representing an area of ​​the second surface; A coil component according to any one of [1] to [5]. [7] The housing further includes an exterior portion including a resin and provided between the first flange and the second flange so as to cover the conductor. A coil component according to any one of [1] to [6]. [8] The arithmetic mean of the first surface height The first Sa is the arithmetic mean of the second surface height More than twice as large as Sa II, A coil component according to any one of [1] to [7]. [9] The arithmetic mean of the first surface height The first Sa is 1 / 20 or more of the average particle size of the plurality of metal magnetic particles; A coil component according to any one of [1] to [8].

[10] the second flange has a second inner side surface facing the inner side surface of the first flange, and an outer side surface facing the second inner side surface and having a lower smoothness than the second side surface, an external electrode provided on the outer surface of the second flange and electrically connected to the conductive wire; A coil component according to any one of [1] to [9].

[11] The first surface is inclined relative to the second surface. A coil component according to any one of [1] to

[10] .

[12] The first surface extends parallel to the second surface. A coil component according to any one of [1] to

[11] .

[13] A step of filling a filling space defined by an inner peripheral surface of the die and an upper end surface of the lower punch with a mixed resin composition obtained by mixing a plurality of soft magnetic metal powders with a resin; a step of compressing the mixed resin composition by moving an upper punch having an inclined surface inclined with respect to a uniaxial direction toward the lower punch along the uniaxial direction to obtain a compression molded body having a first surface extending along the inclined surface and a second surface extending along the uniaxial direction, the first surface having a lower smoothness than the second surface; A step of heating the compression molded body to obtain a powder core; Winding a conductive wire around the dust core so as to contact the first surface; A method for manufacturing a coil component comprising the steps of:

[14] A step of filling a cavity defined by an inner peripheral surface of the die and an upper end surface of the lower punch with a mixed resin composition obtained by mixing a plurality of soft magnetic metal powders with a resin; a step of compressing the mixed resin composition by moving an upper punch, which has a first pressure surface and a second pressure surface disposed closer to the lower punch than the first pressure surface, along a single axis toward the lower punch, to obtain a compression molded body having a first region compressed by the first pressure surface and having a first surface extending along the single axis direction, and a second region compressed by the second pressure surface and having a second surface extending along the single axis direction, the first surface having a lower smoothness than the second surface; A step of heating the compression molded body to obtain a powder core; Winding a conductive wire around the dust core so as to contact the first surface; A method for manufacturing a coil component comprising the steps of: [Explanation of symbols]

[0073] 1, 101, 201 Coil parts 2a Mounting board 3a, 3b Land 10 、 110 cores 11 Roll core 12 First flange 12a Inside surface 12b External surface 12a1 1st page 12a2 2nd side 13 Second flange 13a Inner surface 13b External surface 13a1 1st page 13a2 2nd side 25 Conductor 40 Exterior part 51, 151 dice 52, 152 Upper punch 53, 153 Lower punch

Claims

1. A dust core having a first flange having an inner surface including a first surface and a second surface, a second flange facing the inner surface of the first flange, and a winding core extending in an axial direction and connecting the first flange and the second flange, the dust core being made of a plurality of metal magnetic particles bonded to each other by an insulating material such that the first surface has a lower smoothness than the second surface; a conductive wire wound around the winding core so as to be in contact with the inner surface at the first surface; A coil component comprising:

2. The first surface is disposed at a position closer to the second flange than the second surface in the axial direction. The coil component according to claim 1 .

3. The conductive wire does not contact the second surface. The coil component according to claim 1 or 2.

4. The winding core is in contact with the first surface over a first length and in contact with the second surface over a second length that is shorter than the first length. The coil component according to claim 1 or 2.

5. A first area representing an area of ​​the first surface is smaller than a second area representing an area of ​​the second surface; The coil component according to claim 4 .

6. The housing further includes an exterior portion including a resin and provided between the first flange and the second flange so as to cover the conductor. The coil component according to claim 5 .

7. The arithmetic mean height (first Sa) of the first surface is greater than or equal to two times the arithmetic mean height (second Sa) of the second surface. The coil component according to claim 1 or 2.

8. an arithmetic mean height (first Sa) of the first surface is equal to or greater than 1 / 20 of an average particle size of the plurality of metal magnetic particles; The coil component according to claim 1 or 2.

9. the second flange has a second inner side surface facing the inner side surface of the first flange, and an outer side surface facing the second inner side surface and having a lower smoothness than the second side surface, an external electrode provided on the outer surface of the second flange and electrically connected to the conductive wire; The coil component according to claim 1 or 2.

10. The first surface is inclined relative to the second surface. The coil component according to claim 1 or 2.

11. The first surface extends parallel to the second surface. The coil component according to claim 1 or 2.

12. A step of filling a filling space defined by an inner peripheral surface of the die and an upper end surface of the lower punch with a mixed resin composition obtained by mixing a plurality of soft magnetic metal powders with a resin; a step of compressing the mixed resin composition by moving an upper punch having an inclined surface inclined with respect to a uniaxial direction toward the lower punch along the uniaxial direction to obtain a compression molded body having a first surface extending along the inclined surface and a second surface extending along the uniaxial direction, the first surface having a lower smoothness than the second surface; A step of heating the compression molded body to obtain a powder core; Winding a conductive wire around the dust core so as to contact the first surface; A method for manufacturing a coil component comprising the steps of:

13. A step of filling a cavity defined by an inner peripheral surface of the die and an upper end surface of the lower punch with a mixed resin composition obtained by mixing a plurality of soft magnetic metal powders with a resin; a step of compressing the mixed resin composition by moving an upper punch, which has a first pressure surface and a second pressure surface disposed closer to the lower punch than the first pressure surface, along a uniaxial direction toward the lower punch, to obtain a compression molded body having a first region compressed by the first pressure surface and having a first surface extending along the uniaxial direction, and a second region compressed by the second pressure surface and having a second surface extending along the uniaxial direction, the first surface having a lower smoothness than the second surface; A step of heating the compression molded body to obtain a powder core; Winding a conductive wire around the dust core so as to contact the first surface; A method for manufacturing a coil component comprising the steps of:

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