Coil member, circuit board, and electronic device

Abstract

A coil component of one or more aspects of the present invention includes a base body having a first face, a second face opposite the first face, a third face connecting the first face and the second face, a fourth face opposite the third face, a fifth face connecting the third face and the fourth face, and a sixth face opposite the fifth face; and a coil conductor having a winding portion extending around a coil axis that intersects the first face and the second face. The winding portion has a first portion, a second portion, a third portion, and a fourth portion opposite the third face, the fourth face, the fifth face, and the sixth face when viewed from the direction of the coil axis. The radii of curvature of the first portion and the second portion are each smaller than the radii of curvature of the third portion and the fourth portion. The distance between the first portion and the third face and the distance between the second portion and the fourth face are each greater than the distance between the third portion and the fifth face and the distance between the fourth portion and the sixth face when viewed from the direction of the coil axis.

Description

Technical Field

[0001] This specification discloses information about coil components, circuit boards, and electronic devices. Background Technology

[0002] Various types of coil components are used in electronic devices. Typically, existing coil components have: a magnetic substrate formed of magnetic material; external electrodes disposed on the surface of the magnetic substrate; and a coil conductor extending around the coil axis within the magnetic substrate.

[0003] An inductor can be cited as an example of a coil component. Inductors are passive components used in electronic circuits. Inductors are used, for example, to remove noise from power lines and signal lines. A conventional inductor is disclosed in Japanese Patent Application Publication No. 2018-0101732 (Patent Document 1).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-101732 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The magnetic flux generated when the current flowing through the coil conductor changes passes through the area between the winding portion and the end face and side face of the base. When the size of the base is reduced to make this existing coil component more compact, a sufficiently large area cannot be guaranteed for the magnetic flux to pass between the coil conductor and the surface of the base, thus sometimes resulting in inductance degradation. Conversely, when the distance between the coil conductor and the surface of the base is increased indiscriminately to improve inductance, problems such as an increase in the size of the base may occur.

[0009] One of the objectives of the invention disclosed in this specification is to solve or mitigate the problems of the aforementioned existing coil components. A more specific objective of the invention disclosed in this specification is to provide a coil component that suppresses inductance degradation and is compacted. Other objectives of the invention disclosed in this specification, besides those described above, become more apparent upon reference to this specification as a whole. The invention disclosed in this specification can also replace the aforementioned problems or, based on the aforementioned problems, solve problems mastered according to this specification.

[0010] Technical solutions for solving the problem

[0011] One or more embodiments of the present invention provide a coil component comprising: a substrate made of a magnetic material having a first surface extending in a first direction and a second direction orthogonal to the first direction, wherein a first dimension in the first direction is larger than a second dimension in the second direction; a second surface opposite to the first surface; a third surface connecting an end of the first surface in the first direction to an end of the second surface in the first direction; a fourth surface opposite to the third surface; a fifth surface connecting the third surface and the fourth surface; and a sixth surface opposite to the fifth surface; a coil conductor having a winding portion extending about a coil axis intersecting the first surface and the second surface; a first external electrode disposed on the substrate and electrically connected to one end of the coil conductor; and a second external electrode disposed on the substrate and electrically connected to the other end of the coil conductor. In one or more embodiments, the winding portion includes: a first portion that, when viewed from the direction of the coil axis, is opposite to and bends toward the third surface; a second portion that, when viewed from the direction of the coil axis, is opposite to and bends toward the fourth surface; a third portion that connects the first portion and the second portion and is opposite to the fifth surface; and a fourth portion that connects the first portion and the second portion and is opposite to the sixth surface. In one or more embodiments, the radii of curvature of the first portion and the second portion are both smaller than the radii of curvature of the third portion and the fourth portion. In one or more embodiments, when viewed from the direction of the coil axis, the distance between the first portion and the third surface and the distance between the second portion and the fourth surface are both larger than the distance between the third portion and the fifth surface and the distance between the fourth portion and the sixth surface.

[0012] In one or more embodiments of the present invention, the distance between the first part and the third surface and the distance between the second part and the fourth surface are both within the range of 1.5 to 10 times the distance between the third part and the fifth surface and the distance between the fourth part and the sixth surface.

[0013] In one or more embodiments of the present invention, when viewed from the direction of the coil axis, the distance between the first portion of the winding portion and the third surface is substantially equal to the distance between the second portion of the winding portion and the fourth surface.

[0014] In one or more embodiments of the present invention, when viewed from the direction of the coil axis, the distance between the third portion of the winding portion and the fifth surface is substantially equal to the distance between the fourth portion of the winding portion and the sixth surface.

[0015] In one or more embodiments of the present invention, the winding portion has a uniform cross-sectional area.

[0016] In one or more embodiments of the present invention, the first external electrode is connected to one end of the winding portion via a first lead extending along the coil axis.

[0017] In one or more embodiments of the present invention, the second external electrode is connected to the other end of the winding portion via a second lead-out f extending along the axis of the coil.

[0018] In one or more embodiments of the present invention, the ratio of the area of ​​the winding portion viewed from the direction of the coil axis to the area of ​​the first surface viewed from the direction of the coil axis is 0.3 or more.

[0019] In one embodiment of the present invention, the above-described coil component is used in a DC / DC converter. One embodiment of the present invention relates to a DC / DC converter having the above-described coil component.

[0020] A circuit board based on one embodiment of the present invention has the above-described coil component and a mounting substrate that is brazed to the above-described external electrode.

[0021] An electronic device based on one embodiment of the present invention has the circuit board described above.

[0022] Invention Effects

[0023] According to one or more embodiments of the present invention, it is possible to provide coil components that suppress inductance degradation and are compacted. Attached Figure Description

[0024] Figure 1 This is a perspective view schematically illustrating a coil component according to one embodiment of the present invention.

[0025] Figure 2 yes Figure 1 A schematic top view of the coil component.

[0026] Figure 3 It is a graph showing the relationship between the ratio of the end edge E to the side edge S and the inductance calculated by simulation.

[0027] Figure 4 This is a perspective view schematically illustrating a coil component according to another embodiment of the present invention.

[0028] Figure 5 yes Figure 4 A schematic top view of the coil component.

[0029] Figure 6 This is a perspective view schematically illustrating a coil component according to another embodiment of the present invention.

[0030] Figure 7 It is a schematic representation Figure 6 An exploded perspective view of the coil component.

[0031] Figure 8 yes Figure 6 A schematic top view of the coil component.

[0032] Explanation of reference numerals in the attached figures

[0033] 1, 101, 201 Coil Components

[0034] 10, 110, 210 magnetic matrix

[0035] 21, 22, 121, 122, 221, 222 External electrodes

[0036] 25, 125, 225 coil conductors

[0037] Ax coil shaft

[0038] E1 and E2 end edges

[0039] S1 and S2 side edges. Detailed Implementation

[0040] Hereinafter, various embodiments of the present invention will be described with appropriate reference to the accompanying drawings. Furthermore, common components in the various drawings are labeled with the same reference numerals in those drawings. It should be noted that, for ease of explanation, the drawings are not necessarily shown to precise scale.

[0041] Reference Figure 1 and Figure 2 A coil component 1 according to one embodiment of the present invention will be described. Figure 1 This is a schematic three-dimensional view of coil component 1. Figure 2 This is a schematic top view of coil component 1. Figure 2 The diagram shows a top-view (viewed from the direction of the coil axis Ax, described later) transmission image of the magnetic substrate 10 and the coil conductor 25. In the illustrated embodiment, the coil component 1 is a planar coil having a coil conductor wound with multiple turns in a plane. The coil component 1 includes: a magnetic substrate 10; a coil conductor 25 disposed inside the magnetic substrate 10; an external electrode 21 disposed on the surface of the magnetic substrate 10; and an external electrode 22 disposed on the surface of the substrate 10 and at a position separate from the external electrode 21.

[0042] In this specification, unless the context otherwise requires, the "length", "width", and "height" directions of the coil component 1 are respectively set as follows: Figure 1 The directions of the "L-axis", "W-axis", and "T-axis".

[0043] The coil component 1 is mounted on a mounting substrate. In one embodiment of the present invention, the circuit board has a coil component 1 and a mounting substrate on which the coil component 1 is mounted. Figure 1 The mounting substrate is not shown in the diagram. Two pads are provided on the mounting substrate, and the coil component 1 is mounted on the mounting substrate by engaging the corresponding pads of the external electrodes 21 and 22. The circuit board can be mounted on a wide variety of electronic devices. Electronic devices that can mount the circuit board 2 include smartphones, tablets, game consoles, automotive electrical components, and various other electronic devices.

[0044] Coil component 1 can be applied to inductors, transformers, filters, reactors, and various other coil components. Coil component 1 can also be applied to coupled inductors, chokes, and various other magnetically coupled coil components. Coil component 1 can also be, for example, an inductor used in a DC / DC converter. The application of coil component 1 is not limited to the applications specified in this specification.

[0045] In one embodiment, the substrate 10 is primarily made of magnetic material and has a generally cuboid shape. When referred to as "cuboid" or "cuboid shape" in this specification, it does not refer solely to a "cuboid" in a strictly mathematical sense. The substrate 10 has: a first main surface 10a, a second main surface 10b, a first end surface 10c, a second end surface 10d, a first side surface 10e, and a second side surface 10f. The outer surface of the substrate 10 is defined by these six surfaces. The first main surface 10a and the second main surface 10b respectively form the surfaces at both ends in the height direction, the first end surface 10c and the second end surface 10d respectively form the surfaces at both ends in the length direction, and the first side surface 10e and the second side surface 10f respectively form the surfaces at both ends in the width direction. The first main surface 10a is opposite to the second main surface 10b, the first end surface 10c is opposite to the second end surface 10d, and the first side surface 10e is opposite to the second side surface 10f. The first end face 10c connects one end of the first main face 10a in the positive direction of the L-axis to one end of the second main face 10b in the positive direction of the L-axis. The first main face 10a, the second main face 10b, the first end face 10c, the second end face 10d, the first side face 10e, and the second side face 10f are examples of the first, second, third, fourth, fifth, and sixth faces in the claims, respectively.

[0046] In one embodiment, the first main surface 10a extends in both the L-axis direction and the W-axis direction. In one embodiment, the dimension L1 of the first main surface 10a in the L-axis direction is larger than the dimension W1 in the W-axis direction. In one embodiment, the substrate 10 is formed with a length dimension (dimension in the L-axis direction) L1 of 1.0 mm to 4.5 mm, a width dimension (dimension in the W-axis direction) W1 of 0.5 mm to 3.2 mm, and a height dimension (dimension in the T-axis direction) of 0.5 mm to 5.0 mm. The dimensions of the substrate 10 are not limited to those specifically described in this specification.

[0047] In one embodiment, the magnetic matrix 10 is composed of a composite magnetic material comprising multiple metallic magnetic particles and a binder material. The metallic magnetic particles may also be a mixture of multiple types of metallic magnetic particles having different average particle sizes. In the case where the metallic magnetic particles comprise both large-diameter and small-diameter particles, the average particle size of the large-diameter particles is, for example, 10 μm, and the average particle size of the small-diameter particles is, for example, 1 μm. The binder material bonds the multiple metallic magnetic particles together. The binder material is, for example, a thermosetting resin with excellent insulating properties. The magnetic matrix 10 may also be a pressed powder in which the metallic magnetic particles are bonded together without a binder material. The metallic magnetic particles are composed of various soft magnetic materials. For example, Fe is used as the main component in the metallic magnetic particles. Specifically, the metallic magnetic particles are: (1) metallic particles such as Fe and Ni; (2) crystalline alloy particles such as Fe-Si-Cr alloy, Fe-Si-Al alloy, and Fe-Ni alloy; (3) amorphous alloy particles such as Fe-Si-Cr-B-C alloy and Fe-Si-Cr-B alloy; or (4) mixed particles of these. The composition of the metallic magnetic particles contained in the magnetic matrix 10 is not limited to the above-mentioned compositions. An insulating film made of glass, resin, or other materials with excellent insulating properties may also be provided on the surface of each metallic magnetic particle.

[0048] The coil conductor 25 has: a winding portion 25a wound around a coil axis Ax extending along the thickness direction (T-axis direction); a lead-out portion 25b1 connected to an external electrode 21 at one end of the winding portion 25a; and a lead-out portion 25b2 connected to an external electrode 22 at the other end of the winding portion 25a. In the illustrated embodiment, the coil axis Ax intersects with the first main surface 10a and the second main surface 10b, but does not intersect with the first end surface 10c, the second end surface 10d, the first side surface 10e, and the second side surface 10f. In other words, the first end surface 10c, the second end surface 10d, the first side surface 10e, and the second side surface 10f extend along the coil axis Ax. In one embodiment, the coil axis Ax, when viewed from above the substrate 10, passes through the intersection of the two diagonals of the substrate 10.

[0049] In the illustrated embodiment, the winding portion 25a is wound multiple turns around the coil axis Ax in a plane extending along the LW plane. In the illustrated embodiment, the winding portion 25a has a generally oblong shape. The shape of the winding portion 25a is not limited to the shape illustrated. The shape of the winding portion 25a may also be elliptical, for example. In one embodiment, the cross-sectional area of ​​the winding portion 25a cut in a direction perpendicular to the direction of current flow is uniform.

[0050] In one embodiment, when viewed from above (i.e., from the perspective of the coil axis Ax), the winding portion 25a has: a first portion 25a1 opposite to the first end face 10c; a second portion 25a2 opposite to the second end face 10d; a third portion 25a3 opposite to the first side face 10e; and a fourth portion 25a4 opposite to the second side face 10f.

[0051] In the illustrated embodiment, the first portion 25a1 of the first turn, counting from the lead-out portion 25b1, extends counterclockwise from one end to the other, connecting to the lead-out portion 25b1 at one end. The third portion 25a3 of the first turn extends counterclockwise from one end to the other, connecting to the other end of the first portion 25a1 of the first turn at one end. The second portion 25a2 of the first turn extends counterclockwise from one end to the other, connecting to the other end of the third portion 25a3 of the first turn at one end. The fourth portion 25a4 of the first turn extends counterclockwise from one end to the other, connecting to the other end of the second portion 25a2 of the first turn at one end. The first portion 25a1 of the second turn extends counterclockwise from one end to the other, connecting to the fourth portion 25a4 of the first turn at one end. Similarly, the winding portion 25a extends to and connects to the lead-out portion 25b2. The third part 25a3 and the fourth part 25a4 connect the first part 25a1 and the second part 25a2, respectively.

[0052] In one embodiment, as shown, the first portion 25a1 has a curved surface 26 that bends toward and opposite to a first end face 10c. In another embodiment, as shown, the second portion 25a2 has a curved surface 27 that bends toward and opposite to a second end face 10d. The curved surface 26 of the first portion 25a1 and the curved surface 27 of the second portion 25a2 may have the same or substantially the same radius of curvature. If the difference between the radius of curvature of the curved surface 26 of the first portion 25a1 and the radius of curvature of the curved surface 27 of the second portion 25a2 is less than 10% of the radius of curvature of the curved surface 26 of the first portion 25a1, then it can be said that their radii of curvature are substantially the same.

[0053] In one embodiment, as shown in the figure, the third portion 25a3 has a plane 28 extending parallel to and opposite to the first side surface 10e. The plane 28 can be the entirety or a portion of the surface of the third portion 25a3 opposite to the first side surface 10e. The surface of the third portion 25a3 opposite to the first side surface 10e can also be a composite surface connecting the plane 28 and the curved surface. In one embodiment, the surface of the third portion 25a3 opposite to the first side surface 10e can also be a curved surface that curves protruding towards the first side surface 10e.

[0054] In one embodiment, as shown in the figure, the fourth portion 25a4 has a plane 29 extending parallel to and opposite to the second side surface 10f. Similar to the third portion 25a3, the plane 29 can be all or part of the surface of the fourth portion 25a4 opposite to the second side surface 10f. The surface of the fourth portion 25a4 opposite to the second side surface 10f can be a composite surface connecting the plane 29 and the curved surface. In one embodiment, the surface of the fourth portion 25a4 opposite to the second side surface 10f can also be a curved surface that curves protruding towards the second side surface 10f.

[0055] In one embodiment, the radius of curvature of the first portion 25a1 is smaller than the radii of curvature of either the third portion 25a3 or the fourth portion 25a4. In a more specific embodiment, the radius of curvature of the curved surface 27 of the first portion 25a1 is smaller than the radius of curvature of the surface of the third portion 25a3 opposite to the first side surface 10e and the radius of curvature of the surface of the fourth portion 25a4 opposite to the second side surface 10f. In one embodiment, the radius of curvature of the second portion 25a2 is smaller than the radius of curvature of either the third portion 25a3 or the fourth portion 25a4. In a more specific embodiment, the radius of curvature of the curved surface 27 of the second portion 25a2 is smaller than the radius of curvature of the surface of the third portion 25a3 opposite to the first side surface 10e and the radius of curvature of the surface of the fourth portion 25a4 opposite to the second side surface 10f. When the radius of curvature of the first part 25a1 is not fixed, the average of the radii of curvature of multiple points (e.g., 3 or 5 points) evenly distributed around the coil axis Ax in the first part 25a1 can be set as the radius of curvature of the first part 25a1, or the maximum value of the radius of curvature in the first part 25a1 can be set as the radius of curvature of the first part 25a1. When the radii of curvature of the second part 25a2, the third part 25a3, and the fourth part 25a4 are not fixed, their radii of curvature can be determined in the same way as when the radius of curvature of the first part 25a1 is not fixed.

[0056] In one embodiment, the first portion 25a1 includes the intersection point P1 of a perpendicular line from the coil axis Ax to the first end face 10c and the outermost turn of the winding portion 25a. In one embodiment, the second portion 25a2 includes the intersection point P2 of a perpendicular line from the coil axis Ax to the second end face 10d and the outermost turn of the winding portion 25a. In one embodiment, the third portion 25a3 includes the intersection point P3 of a perpendicular line from the coil axis Ax to the first side face 10e and the outermost turn of the winding portion 25a. In one embodiment, the fourth portion 25a4 includes the intersection point P4 of a perpendicular line from the coil axis Ax to the second side face 10f and the outermost turn of the winding portion 25a.

[0057] The boundaries between adjacent portions of the first part 25a1, the second part 25a2, the third part 25a3, and the fourth part 25a4 can be determined, for example, as described below. Viewed from the direction of the coil axis Ax, imaginary lines connecting the coil axis Ax to the four corners of the base 10 are determined, and these four imaginary lines can be used as the boundaries between the four portions of the first part 25a1, the second part 25a2, the third part 25a3, and the fourth part 25a4 and their adjacent portions. For example, using... Figure 2 From this perspective, the imaginary line connecting the upper left corner of the base 10 and the coil axis Ax can be set as the boundary line between the first part 25a1 and the fourth part 25a4. Similarly, with Figure 2 From this perspective, the imaginary lines connecting the upper right, lower right, and lower left corners of the base 10 to the coil axis Ax can be set as the boundary lines between the fourth part 25a4 and the second part 25a2, the second part 25a2 and the third part 25a3, and the third part 25a3 and the first part 25a1, respectively.

[0058] In one embodiment, the first end edge E1, representing the distance between the first portion 25a1 of the winding portion 25a and the first end face 10c of the substrate 10, is larger than either the first side edge S1, representing the distance between the third portion 25a3 of the winding portion 25a and the first side face 10e of the substrate 10, or the second side edge S2, representing the distance between the fourth portion 25a4 of the winding portion 25a and the second side face 10f of the substrate 10. In one embodiment, the second end edge E2, representing the distance between the second portion 25a2 of the winding portion 25a and the second end face 10d of the substrate 10, is larger than either the first side edge S1 or the second side edge S2. In one embodiment, both end edges E1 and E2 are within the range of 1.5 to 10 times the size of the side edges S1 and S2.

[0059] In one embodiment, the first end edge E1 and the second end edge E2 may be the same or substantially the same. When the difference between the first end edge E1 and the second end edge E2 is less than 10% of the first end edge E1, it can be said that the first end edge E1 and the second end edge E2 are substantially the same.

[0060] In one embodiment, the first side edge S1 and the second side edge S2 may be the same or substantially the same. When the difference between the first side edge S1 and the second side edge S2 is less than 10% of the first side edge S1, it can be said that the first side edge S1 and the second side edge S2 are substantially the same.

[0061] As shown in the figure, in one embodiment, the lead-out portion 25b1 extends along the coil axis Ax. In another embodiment, the lead-out portion 25b2 extends along the coil axis Ax. When the area occupied by the lead-out portion in a cross-section perpendicular to the coil axis Ax increases, the inductance of the coil component 1 may deteriorate because the lead-out portion obstructs the passage of magnetic flux. According to the illustrated embodiment, one end of the winding portion 25a is connected to the external electrode 21 using the lead-out portion 25b1 extending along the coil axis Ax, thus suppressing the deterioration of inductance caused by connecting one end of the winding portion 25a to the lead-out portion of the external electrode 21. Furthermore, according to the illustrated embodiment, the other end of the winding portion 225a is connected to the external electrode 22 using the lead-out portion 25b2 extending along the coil axis Ax, thus suppressing the deterioration of inductance caused by connecting the other end of the winding portion 25a to the lead-out portion of the external electrode 21.

[0062] In one embodiment, the ratio of the area of ​​the winding portion 25a viewed from the direction of the coil axis Ax to the area of ​​the first main surface 10a is 0.3 or more. When the shape of the first main surface 10a viewed from the direction of the coil axis Ax is rectangular, its dimension in the L-axis direction is L1 and its dimension in the W-axis direction is W1. Therefore, the area S1 of the first main surface 10a viewed from the direction of the coil axis Ax becomes S1 = L1 × W1. When the area of ​​the winding portion 25a viewed from the direction of the coil axis Ax is set to S2, in one embodiment, S2 / S1 is 0.3 or more. A coil component capable of carrying a large current while maintaining a compact external size is required. To achieve such a coil component, there is a tendency to increase the cross-sectional area of ​​the coil conductor. When the cross-sectional area of ​​the coil conductor increases, the area S2 of the winding portion 25a viewed from the direction of the coil axis Ax also increases. Especially as S2 / S1 increases to 0.3 and S2 increases further, the inductance may deteriorate in areas where magnetic flux cannot be adequately ensured when the side and end edges are set to be the same. Therefore, when S2 / S1 is 0.3 or higher, optimizing the ratio of the side and end edges to design a sufficient area for magnetic flux passage is effective. Furthermore, if S2 / S1 is below 0.3, even if the side and end edges are designed to be the same, the area for magnetic flux passage can be adequately ensured, and thus the inductance will not deteriorate to a level that becomes problematic in practical use.

[0063] Next, an example of a method for manufacturing a coil component 1 according to one embodiment of the present invention will be described. Hereinafter, an example of a method for manufacturing a coil component 1 based on a compression molding process will be described. First, metallic magnetic particles are prepared. An insulating film is provided on the surface of the metallic magnetic particles as needed. These metallic magnetic particles may also be a mixture of various particles with different average particle sizes. Next, the prepared metallic magnetic particles, resin material, and diluent are mixed to produce a composite magnetic material. The composite magnetic material is placed into a pre-prepared molding die containing a coil conductor 25, and molding pressure is applied, for example, at a temperature of 50°C to 150°C. Further, it is heated and cured at 150°C to 400°C, thereby obtaining a magnetic matrix 10 containing a coil conductor 25 internally. The coil conductor 25 is configured and arranged such that, when viewed from the direction of the coil axis Ax, the first end edge E1 and the second end edge E2 are larger than either the first side edge S1 or the second side edge S2.

[0064] The heat treatment for obtaining the magnetic substrate 10 can be performed in two stages as described above, or in one stage. In the case of a one-stage heat treatment, forming and curing occur during the heat treatment. In the substrate 10, the resin contained in the composite magnetic material cures to become a bonding material. The substrate 10 can also be formed, for example, at a temperature of approximately 80°C. The forming pressure is, for example, set to 50 MPa to 200 MPa. The forming pressure can be appropriately adjusted to obtain the desired filling rate. The forming pressure is, for example, set to 100 MPa.

[0065] Next, external electrodes 21 and 22 are formed by applying conductive paste to the surface of the magnetic substrate 10 obtained as described above. External electrode 21 is electrically connected to one end of the coil conductor 25 disposed within the magnetic substrate 10, and external electrode 22 is electrically connected to the other end of the coil conductor 25 disposed within the magnetic substrate 10. Through the above, coil component 1 is obtained.

[0066] The manufactured coil component 1 is mounted on a mounting substrate through a reflow soldering process. In this case, after the mounting substrate on which the coil component 1 is disposed passes through a reflow oven heated to a peak temperature of 260°C at high speed, the external electrodes 21 and 22 are respectively brazed to the pad portion of the mounting substrate, thereby mounting the coil component 1 on the mounting substrate and manufacturing a circuit board.

[0067] Next, the inductor characteristics of the coil component 1 according to one embodiment will be described. To simulate the inductor characteristics, four evaluation models (evaluation model #1 to evaluation model #4) were constructed. Each of evaluation models #1 to #4 is a model of the coil component 1. Each of evaluation models #1 to #4 has a cuboid base corresponding to the base 10, a conductor corresponding to the coil conductor 25, and two electrodes corresponding to the external electrodes 21 and 22, respectively. The length dimension (dimension in the L-axis direction) of the base is set to 2.0 mm, the width dimension (dimension in the W-axis direction) is set to 1.2 mm, and the height dimension (dimension in the T-axis direction) is set to 1.2 mm. In each evaluation model, the conductor corresponding to the coil conductor 25 is wound only 10.5 turns around the coil axis corresponding to the coil axis Ax. In evaluation model #1, the distance from the conductor to the surface of the base when viewed from the direction of the coil axis is set to 0.25 mm. That is, in evaluation model #1, both the end edge and the side edge are set to 0.25 mm. In each evaluation model, the end edge (or side edge) where the end edge and the side edge are equal is called the reference edge. In evaluation models #2 to #4, the reference edge is set to 0.2 mm, 0.15 mm, and 0.1 mm, respectively.

[0068] For each of the evaluation models #1 to #4 constructed as described above, while maintaining the total of the end edge and side edge at a constant value (twice that of the reference edge), the end edge and side edge are increased or decreased by 0.05 mm each time, and the inductance L after such changes in the end edge and side edge is calculated by simulation. Figure 3 The result is represented in the figure. Figure 3 This is a graph showing the simulation results of the inductance L for evaluation models #1 to #4. The horizontal axis represents the ratio of the end edge E to the side edge S on a logarithmic scale, and the vertical axis represents the calculated inductance. Figure 3 In the evaluation model #1 with a reference edge of 0.25mm, the simulation results of the inductance when the end edge and the reference edge are equal are plotted at the origin of the X-axis (E / S = 1). To the right of one of the plotting points located at this origin, the simulation results of the inductance when the end edge is increased by only 0.05 from the reference edge (set to 0.30mm) and the side edge is decreased by only 0.05 from the reference edge (set to 0.20mm) are plotted at X = 1.5 (= 0.3 / 0.2) on the X-axis. Other simulation results are calculated similarly. Figure 3 The calculated simulation results are plotted in the chart. Furthermore, in cases where the end or side edge becomes zero by reducing it by 0.05 mm, 0.01 is used instead of zero for ease of calculation.

[0069] As shown in the figure, when the reference edge is any of 0.10 to 0.25 mm, the inductance can be improved by making the dimension corresponding to the end edge larger than that of the side edge.

[0070] Next, refer to Figure 4 and Figure 5 A coil component 101 according to another embodiment of the present invention will be described. The coil component 101 differs from the coil component 1, which has a coil conductor 25a wound in a spiral shape, in that it has a coil conductor wound in a spiral shape.

[0071] like Figure 4 and Figure 5 As shown, the coil component 101 includes: a coil conductor 125 disposed within a magnetic substrate 110; an external electrode 121 disposed in the magnetic substrate 110; and an external electrode 122 disposed in the magnetic substrate 110 at a distance from the external electrode 121. Similar to the magnetic substrate 10, the magnetic substrate 110 is formed of a magnetic material.

[0072] The coil component 101 can also be mounted on the mounting substrate 2a. Two pad portions 3 are provided on the mounting substrate 2a. The coil component 1 is mounted on the mounting substrate 2a by engaging the external electrodes 21 and 22 with their respective pad portions 3 on the mounting substrate 2a. The circuit board 2 is constructed by mounting the coil component 101 on the mounting substrate 2a. The circuit board 2 has the coil component 101 and the mounting substrate 2a on which the coil component 1 is mounted. The circuit board 2 can have electronic components other than the coil component 101.

[0073] The magnetic substrate 110 has a generally rectangular parallelepiped shape. The magnetic substrate 110 has: a first main surface 110a, a second main surface 110b, a first end surface 110c, a second end surface 110d, a first side surface 110e, and a second side surface 110f. The outer surface of the magnetic substrate 110 is defined by these six surfaces. The first main surface 110a and the second main surface 110b respectively form the surfaces at both ends in the height direction, the first end surface 110c and the second end surface 110d respectively form the surfaces at both ends in the length direction, and the first side surface 110e and the second side surface 110f respectively form the surfaces at both ends in the width direction. The description relating to the magnetic substrate 10 also applies as much as possible to the magnetic substrate 110.

[0074] The coil conductor 125 has: a winding portion 125a that is wound into a spiral shape around a coil axis Ax extending along the thickness direction (T direction); a lead-out portion 125b1 that connects one end of the winding portion 125a to the external electrode 121; and a lead-out portion 125b2 that connects the other end of the winding portion 125a to the external electrode 122.

[0075] Similar to the winding portion 25a, the winding portion 125a has: a first portion 125a1 opposite to the first end face 110c; a second portion 125a2 opposite to the second end face 110d; a third portion 125a3 opposite to the first side face 110e; and a fourth portion 125a4 opposite to the second side face 110f. In the illustrated embodiment, the fourth portion 125a4, counting the first turn from the lead-out portion 125b1, extends clockwise from one end to the other and connects to the lead-out portion 125b1 at one end. The second portion 125a2 of the first turn extends clockwise from one end to the other and connects to the other end of the fourth portion 125a4 of the first turn at one end. The third portion 125a3 of the first turn extends clockwise from one end to the other and connects to the other end of the second portion 125a2 of the first turn at one end. The first portion 125a1 of the first turn extends clockwise from one end to the other, connecting at one end to the other end of the third portion 125a3 of the first turn. The third portion 125a3 of the second turn extends clockwise from one end to the other, connecting at one end to the other end of the first portion 125a1 of the first turn. Similarly, the winding portion 125a extends to and connects to the lead-out portion 125b2. As described above, the third portion 125a3 and the fourth portion 125a4 connect the first portion 125a1 and the second portion 125a2, respectively. The boundaries between adjacent portions of the first portion 125a1, the second portion 125a2, the third portion 125a3, and the fourth portion 125a4 can be determined in the same way as the boundaries between the portions of the winding portion 25a. For example, from the direction of the coil axis Ax, one can determine the imaginary lines connecting the coil axis Ax and the four corners of the base 110, and set these four imaginary lines as the boundary lines between the four parts of the first part 125a1, the second part 125a2, the third part 125a3 and the fourth part 125a4 and their adjacent parts.

[0076] In one embodiment, as shown, the first portion 125a1 has a curved surface 126 that bends toward and opposite to a first end face 110c. In one embodiment, as shown, the second portion 125a2 has a curved surface 127 that bends toward and opposite to a second end face 110d. In one embodiment, as shown, the third portion 125a3 has a curved surface 128 that bends toward and opposite to a first side face 110e. In one embodiment, as shown, the fourth portion 125a4 has a curved surface 129 that bends toward and opposite to a second side face 110f.

[0077] In one embodiment, the radius of curvature of the first portion 125a1 is smaller than the radii of curvature of either the third portion 125a3 or the fourth portion 125a4. In a more specific embodiment, the radius of curvature of the curved surface 126 of the first portion 125a1 is smaller than the radius of curvature of either the curved surface 128 of the third portion 125a3 or the curved surface 129 of the fourth portion 125a4. In one embodiment, the radius of curvature of the second portion 125a2 is smaller than the radius of curvature of either the third portion 125a3 or the fourth portion 125a4. In a more specific embodiment, the radius of curvature of the curved surface 127 of the second portion 125a2 is smaller than the radius of curvature of either the curved surface 128 of the third portion 125a3 or the curved surface 129 of the fourth portion 125a4. When the radius of curvature of the first part 125a1 is not fixed, the average of the radii of curvature of multiple points (e.g., 3 or 5 points) evenly distributed around the coil axis Ax in the first part 125a1 can be set as the radius of curvature of the first part 125a1, or the maximum value of the radius of curvature in the first part 125a1 can be set as the radius of curvature of the first part 125a1. Similarly, when the radii of curvature of the second part 125a2, the third part 125a3, and the fourth part 125a4 are not fixed, their radii of curvature can be determined in the same way as when the radius of curvature of the first part 125a1 is not fixed.

[0078] The arrangement of the winding portion 125a in coil component 101 relative to the base 110 is the same as the arrangement of the winding portion 25a in coil component 1 relative to the base 10 described above. For example, in one embodiment, the first end edge E1, which represents the distance between the first portion 125a1 of the winding portion 125a and the first end face 110c of the base 110, is larger than either the first side edge S1, which represents the distance between the third portion 125a3 of the winding portion 125a and the first side face 110e of the base 110, or the second side edge S2, which represents the distance between the fourth portion 125a4 of the winding portion 125a and the second side face 110f of the base 110. Furthermore, in one embodiment, the second end edge E2, which represents the distance between the second portion 125a2 of the winding portion 125a and the second end face 110d of the base 110, is larger than either the first side edge S1 or the second side edge S2.

[0079] Similar to coil component 1, coil component 101 can be manufactured by compression molding. The manufactured coil component 101 is mounted on mounting substrate 2 by reflow soldering. In this case, after the substrate 2 on which coil component 1 is disposed passes through a reflow oven heated to a peak temperature of, for example, 260°C at high speed, external electrodes 121 and 122 are soldered to the pad portions 3 of the substrate 2, thereby mounting coil component 101 on mounting substrate 2a and manufacturing circuit board 2.

[0080] Next, refer to Figures 6 to 8 Another embodiment of the coil component 201 of the present invention will be described. The coil component 201 is a stacked coil. As shown in the figure, the coil component 201 includes: a magnetic substrate 210; a coil conductor 225 disposed within the magnetic substrate 210; an external electrode 221 disposed in the magnetic substrate 210; and an external electrode 222 disposed in the magnetic substrate 210 at a distance from the external electrode 221. Similar to the magnetic substrate 10, the magnetic substrate 210 is made of a magnetic material.

[0081] The magnetic substrate 210 is formed into a cuboid shape from a magnetic material. The magnetic substrate 210 includes: a magnetic body layer 220 with an embedded coil 225; an upper cover layer 218 made of magnetic material disposed on the upper surface of the magnetic body layer 220; and a lower cover layer 219 made of magnetic material disposed on the lower surface of the magnetic body layer 220. The upper cover layer 218 has magnetic films 218a to 218d made of magnetic material, and the lower cover layer 219 has magnetic films 219a to 219d made of magnetic material. The boundaries between the magnetic body layer 220 and the upper cover layer 218, and between the magnetic body layer 220 and the lower cover layer 219, are sometimes not clearly defined depending on the manufacturing method of the magnetic substrate 10. The magnetic substrate 210 has a generally cuboid shape and includes a first main surface 210a, a second main surface 210b, a first end surface 210c, a second end surface 210d, a first side surface 210e, and a second side surface 210f. The outer surface of the magnetic substrate 210 is defined by these six surfaces. The first main surface 210a and the second main surface 210b form the surfaces at both ends in the height direction, the first end surface 210c and the second end surface 210d form the surfaces at both ends in the length direction, and the first side surface 210e and the second side surface 210f form the surfaces at both ends in the width direction. The description relating to the magnetic substrate 10 also applies as much as possible to the magnetic substrate 210.

[0082] The magnetic layer 220 has magnetic films 211 to 214. In the magnetic layer 220, magnetic films 211, 212, 213, and 214 are sequentially stacked from the positive direction to the negative direction along the T-axis. Conductor patterns C11 to C14 are formed on the upper surface of each of the magnetic films 211 to 214. The conductor patterns C11 to C14 are formed, for example, by screen printing a conductive paste made of a metal or alloy with excellent conductivity. Ag, Pd, Cu, Al, or alloys thereof can be used as the material for this conductive paste.

[0083] Conductive holes V1 to V3 are formed at predetermined positions on magnetic films 211 to 213. These conductive holes V1 to V3 are formed by creating through-holes in the T-axis direction of magnetic films 211 to 213 at predetermined positions, and embedding conductive material within these through-holes. Conductor patterns C11 to C14 are electrically connected via adjacent conductor patterns and conductive holes V1 to V3. These connected conductor patterns C11 to C14 form a helical coil conductor 225.

[0084] like Figure 7 As shown, the coil conductor 225 has: a winding portion 225a that is wound into a spiral shape around a coil axis Ax extending along the thickness direction (T direction); a lead-out portion 225b1 that connects one end of the winding portion 225a to the external electrode 221; and a lead-out portion 225b2 that connects the other end of the winding portion 225a to the external electrode 222.

[0085] Similar to the winding portion 25a, the winding portion 225a has: a first portion 225a1 opposite to the first end face 210c; a second portion 225a2 opposite to the second end face 210d; a third portion 225a3 opposite to the first side face 210e; and a fourth portion 225a4 opposite to the second side face 210f. In the illustrated embodiment, the first portion 225a1 of the first turn extends clockwise from one end to the other and is connected to the lead-out portion 225b1 at one end. The fourth portion 225a4 of the first turn extends clockwise from one end to the other and is connected to the other end of the first portion 225a1 of the first turn at one end. The second portion 225a2 of the first turn extends clockwise from one end to the other and is connected to the other end of the fourth portion 225a4 of the first turn at one end. The third portion 125a4 of the first turn extends clockwise from one end to the other, connecting at one end to the other end of the second portion 125a2. The first portion 225a1 of the second turn extends clockwise from one end to the other, connecting at one end to the other end of the third portion 125a3 of the first turn. Similarly, the winding portion 225a extends to and connects to the lead-out portion 225b2. As described above, the third portion 225a3 and the fourth portion 225a4 connect the first portion 225a1 and the second portion 225a2, respectively. The boundaries between adjacent portions of the first portion 225a1, the second portion 225a2, the third portion 225a3, and the fourth portion 225a4 can be determined in the same way as the boundaries between the portions of the winding portion 25a. For example, by observing from the direction of the coil axis Ax, imaginary lines connecting the coil axis Ax and the four corners of the base 210 can be determined, and these four imaginary lines can be used as the dividing lines between the four parts of the first part 225a1, the second part 225a2, the third part 225a3 and the fourth part 225a4 and their adjacent parts.

[0086] In one embodiment, as shown, the first portion 225a1 has a curved surface 226 that bends toward and opposite to the first end face 210c. In one embodiment, as shown, the second portion 225a2 has a curved surface 227 that bends toward and opposite to the second end face 210d. In one embodiment, as shown, the third portion 225a3 has a curved surface 228 that bends toward and opposite to the first side face 210e. In one embodiment, as shown, the fourth portion 225a4 has a curved surface 229 that bends toward and opposite to the second side face 210f.

[0087] In one embodiment, the radius of curvature of the first portion 225a1 is smaller than the radii of curvature of either the third portion 225a3 or the fourth portion 225a4. In a more specific embodiment, the radius of curvature of the curved surface 226 of the first portion 225a1 is smaller than the radius of curvature of either the curved surface 128 of the third portion 225a3 or the curved surface 229 of the fourth portion 225a4. In one embodiment, the radius of curvature of the second portion 225a2 is smaller than the radius of curvature of either the third portion 225a3 or the fourth portion 225a4. In a more specific embodiment, the radius of curvature of the curved surface 227 of the second portion 225a2 is smaller than the radius of curvature of either the curved surface 228 of the third portion 225a3 or the curved surface 229 of the fourth portion 225a4. When the radius of curvature of the first part 225a1 is not fixed, the average of the radii of curvature of multiple points (e.g., 3 or 5 points) evenly distributed around the coil axis Ax in the first part 225a1 can be set as the radius of curvature of the first part 225a1, or the maximum value of the radius of curvature in the first part 225a1 can be set as the radius of curvature of the first part 225a1. When the radii of curvature of the second part 225a2, the third part 225a3, and the fourth part 225a4 are not fixed, their radii of curvature can be determined in the same way as when the radius of curvature of the first part 225a1 is not fixed.

[0088] The arrangement of the winding portion 225a in coil component 201 relative to the base 210 is the same as the arrangement of the winding portion 25a in coil component 1 relative to the base 10. For example, in one embodiment, the first end edge E1, which represents the distance between the first portion 225a1 of the winding portion 225a and the first end face 210c of the base 210, is larger than either the first side edge S1, which represents the distance between the third portion 225a3 of the winding portion 225a and the first side face 210e of the base 210, or the second side edge S2, which represents the distance between the fourth portion 225a4 of the winding portion 225a and the second side face 210f of the base 210. Furthermore, in one embodiment, the second end edge E2, which represents the distance between the second portion 225a2 of the winding portion 225a and the second end face 210d of the base 210, is larger than either the first side edge S1 or the second side edge S2.

[0089] Next, an example of a method for manufacturing the coil component 201 will be described. The coil component 201 can be manufactured, for example, by a lamination process. Hereinafter, an example of a method for manufacturing the coil component 201 by a lamination process will be described.

[0090] First, magnetic sheets are fabricated, which consist of magnetic films 218a-218d constituting the upper cover layer 218, magnetic films 211-214 constituting the magnetic layer 220, and magnetic films 219a-219d constituting the lower cover layer 219. These magnetic sheets are formed from a composite magnetic material containing a bonding material and metallic magnetic particles. The magnetic sheets used for the coil component 201 can be fabricated using the same method as the magnetic sheets used in the manufacturing process of the coil component 1.

[0091] Next, a coil conductor is placed relative to the magnetic sheet. Specifically, through holes extending through each magnetic sheet in the T-axis direction are formed at predetermined positions on each of the magnetic sheets that become magnetic films 211 to 213. Next, conductive paste is printed onto the upper surface of each of the magnetic sheets that become magnetic films 211 to 214 using screen printing, thereby forming an unburned conductor pattern on the magnetic sheet. Furthermore, conductive paste is embedded in each through hole formed in each magnetic sheet.

[0092] Next, magnetic sheets that will become magnetic films 211 to 214 are stacked to obtain a coil stack. Each magnetic sheet that becomes magnetic film 211 to 214 is stacked in such a way that the unburned conductor patterns C11 to C14 formed on each magnetic sheet are electrically connected through adjacent conductor patterns and unburned through holes V1 to V3.

[0093] Next, multiple magnetic sheets are stacked to form an upper layer 218. Additionally, multiple magnetic sheets are stacked to form a lower layer 219.

[0094] Next, the lower stack, coil stack, and upper stack are stacked in this order from the negative direction to the positive direction along the T-axis. The stacked layers are then heat-pressed together using a stamping machine to obtain the main stack. Alternatively, the main stack can be formed by skipping the lower, coil, and upper stacks and instead stacking all the prepared magnetic sheets sequentially and heat-pressing them together.

[0095] Next, the main body laminate is cut into single pieces of the desired size using a cutting machine or laser processing machine to obtain a chip laminate. Then, the chip laminate is degreased and subjected to heat treatment. If necessary, the ends of the chip laminate are subjected to grinding treatments such as tumbling.

[0096] Next, external electrodes 221 and 222 are formed by applying conductive paste to both ends of the chip stack. Through the above process, coil component 201 is obtained.

[0097] Next, the effects of the above-described embodiments will be explained. In order to effectively utilize each region of the substrate magnetically, conventional coil components are designed with identical end edges and side edges to avoid magnetic flux concentration in specific areas of the substrate. Furthermore, in conventional coil components, to prevent the coil conductor winding from protruding from the substrate and to prevent short circuits between the winding and external conductive components, certain edges are provided between the winding and the end and side faces of the substrate. When manufacturing coil components using a lamination process, the conductor pattern printing may deviate from its initial position, or the magnetic sheets may deviate from each other when multiple magnetic sheets are laminated, or the cutting position may deviate during the single-piece manufacturing process. This deviation occurs equally in both the length direction (L-axis direction) and the width direction (W-axis direction). Therefore, to avoid adverse conditions caused by this deviation (e.g., exposure of the winding), the edges provided between the winding and the substrate surfaces are set in the same manner in both the length and width directions. When manufacturing coil components using a compression molding process with a mold, a certain distance is required between the wall of the mold containing the composite magnetic material and the winding portion of the coil conductor embedded within the mold. This required distance is the same in both the length and width directions. As mentioned above, existing coil components are designed with identical or substantially identical end edges and side edges. On the other hand, when viewed from the coil axis, the coil conductor sometimes takes a shape such as an oblong or elliptical shape, where the dimension in one direction perpendicular to the coil conductor is larger than the dimension in another direction perpendicular to the coil conductor. Therefore, the winding portion of the coil conductor sometimes includes sections with a smaller radius of curvature and sections with a larger radius of curvature. When the current flowing through the coil conductor changes, the magnetic flux is more likely to concentrate around the section with a smaller radius of curvature compared to the area around the section with a larger radius of curvature. In one or more embodiments of the present invention, the winding portions 25a, 125a, 225a have first portions 25a1, 125a1, 225a1 and second portions 25a2, 125a2, 225a2 with small radii of curvature, and third portions 25a3, 125a3, 225a3 and fourth portions 25a4, 125a4, 225a4 with larger radii of curvature. Therefore, in the substrates 10, 110, 210, magnetic flux tends to concentrate in the regions between the first portions 25a1, 125a1, 225a1 and the first end faces 10c, 110c, 210c, and in the regions between the second portions 25a2, 125a2, 225a2 and the second end faces 10d, 110d, 210d.

[0098] In one or more embodiments of the present invention, the distance between the first portions 25a1, 125a1, 225a1 of the winding portions 25a, 125a, 225a and the first end faces 10c, 110c, 210c, i.e., the end edge E1, is greater than the distance between the third portions 25a3, 125a3, 225a3 and the first side faces 10e, 110e, 210e, i.e., the side edge S1, and the distance between the third portions 25a3, 125a3, 225a3 and the fourth portions 25a4, 125a4, 225a4, i.e., the side edge S2. Therefore, it is possible to suppress the concentration of magnetic flux in the area between the first portions 25a1, 125a1, 225a1 of the winding portions 25a, 125a, 225a with smaller radii of curvature and the surfaces of the substrates 10, 110, 210. Furthermore, in one or more embodiments of the present invention, the distance between the second portions 25a2, 125a2, 225a2 of the winding portions 25a, 125a, 225a2 and the second end faces 10d, 110d, 210d, i.e., the end edge E2, is greater than the side edges S1 and S2. Therefore, it is possible to suppress the concentration of magnetic flux in the area between the second portions 25a2, 125a2, 225a2 of the winding portions 25a, 125a, 225a2 with smaller radii of curvature and the surfaces of the substrates 10, 110, 210.

[0099] Furthermore, in one or more embodiments of the present invention, the side edges S1 and S2 are smaller than the end edges E1 and E2. Therefore, compared with conventional coil components with equal side edges and end edges, the overall size of the substrate can be miniaturized. In other words, by selectively increasing the end edge E1, which contributes to the area of ​​the region between the first portions 25a1, 125a1, 225a1 where magnetic flux tends to concentrate and the first end faces 10c, 110c, 210c, and the end edge E2, which contributes to the area of ​​the region between the second portions 25a2, 125a2, 225a2 and the second end faces 10d, 110d, 210d, the degradation of inductance can be suppressed without increasing the size of the substrate 10 in the width direction.

[0100] Thus, according to one or more embodiments of the present invention, by making the end edges E1 and E2 larger than the side edges S1 and S2, it is possible to suppress the concentration of magnetic flux in the regions between the first portions 25a1, 125a1, 225a1 and the first end faces 10c, 110c, 210c, and the regions between the second portions 25a2, 125a2, 225a2 and the second end faces 10d, 110d, 210d, and to suppress inductance degradation, and to miniaturize the external dimensions of the substrates 10, 110, 210. Therefore, according to one or more embodiments of the present invention, it is possible to provide coil components 1, 101, 201 that suppress inductance degradation and are compacted.

[0101] The dimensions, materials, and configurations of the constituent elements described in the various embodiments above are not limited to those explicitly described in each embodiment. These constituent elements can be modified in any size, material, and configuration that is within the scope of this invention. Furthermore, constituent elements not explicitly described in this specification can be added to the various embodiments above, and some constituent elements described in each embodiment can be omitted.

Claims

1. A coil component, characterized in that, include: A matrix made of magnetic material has a first surface extending in a first direction and a second direction orthogonal to the first direction, wherein a first dimension in the first direction is larger than a second dimension in the second direction; a second surface opposite to the first surface; a third surface connecting the end of the first surface in the first direction to the end of the second surface in the first direction; a fourth surface opposite to the third surface; a fifth surface connecting the third surface and the fourth surface; and a sixth surface opposite to the fifth surface. A coil conductor having a wound portion but not a portion bent at an acute angle, the wound portion extending about a coil axis intersecting the first and second surfaces; A first external electrode is disposed on the substrate and electrically connected to one end of the coil conductor; and A second external electrode is disposed on the substrate and electrically connected to the other end of the coil conductor. The winding portion has a first portion that is opposite to and bent toward the third surface when viewed from the direction of the coil axis; A second portion that is opposite to and bends toward the fourth surface; a third portion that connects the first portion and the second portion and is opposite to the fifth surface; and a fourth portion that connects the first portion and the second portion and is opposite to the sixth surface. The radii of curvature of the first and second parts are both smaller than those of the third and fourth parts. When viewed from the direction of the coil axis, the distance between the first part and the third surface and the distance between the second part and the fourth surface are both greater than the distance between the third part and the fifth surface and the distance between the fourth part and the sixth surface. The distance between the first part and the third surface, and the distance between the second part and the fourth surface, are both within the range of 1.5 to 10 times the distance between the third part and the fifth surface, and the distance between the fourth part and the sixth surface, respectively. The ratio of the area of ​​the wound portion as viewed from the direction of the coil axis to the area of ​​the first surface as viewed from the direction of the coil axis is 0.3 or more.

2. The coil component according to claim 1, characterized in that: When viewed from the direction of the coil axis, the distance between the first portion of the winding and the third surface is substantially equal to the distance between the second portion of the winding and the fourth surface.

3. The coil component according to claim 1 or 2, characterized in that: When viewed from the direction of the coil axis, the distance between the third portion of the winding portion and the fifth surface is substantially equal to the distance between the fourth portion of the winding portion and the sixth surface.

4. The coil component according to any one of claims 1 to 3, characterized in that: The winding section has a uniform cross-sectional area.

5. The coil component according to any one of claims 1 to 4, characterized in that: The first external electrode is connected to one end of the winding portion via a first lead-out extending along the axis of the coil.

6. The coil component according to any one of claims 1 to 5, characterized in that: The second external electrode is connected to the other end of the winding portion via a second lead extending along the axis of the coil.

7. A DC / DC converter, characterized in that: A coil component having any one of claims 1 to 6.

8. A circuit board, characterized in that, include: The coil component according to any one of claims 1 to 6; and The mounting substrate is brazed to the external electrode.

9. An electronic device, characterized in that: It has the circuit board as described in claim 8.

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