Drum-shaped core

Abstract

To prevent a flange side surface from being cracked.SOLUTION: A drum-shaped core includes: a pair of flange portions; and a winding core portion extending in a first direction between the pair of flange portions and connecting the pair of flange portions to each other. The flange portion includes: a first main surface extending along a first direction and a second direction orthogonal to the first direction in a plan view; and a second main surface opposite to the first main surface. A side surface of the flange portion in the second direction includes a first side surface and a second side surface connected to the first side surface and located closer to the first main surface than the first side surface. Each of the first side surface and the second side surface has inclination with respect to a third direction orthogonal to each of the first direction and the second direction. An inclination angle of the second side surface with respect to the third direction is larger than that of the first side surface with respect to the third direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technique that is effective when applied to a drum-shaped core that constitutes a coil component. [Background technology]

[0002] A drum-shaped core is one of the components that constitute a coil component. The drum-shaped core has a winding core portion around which a wire is wound and a pair of flange portions provided on each end of the winding core portion.

[0003] Patent Document 1 (Utility Model Registration No. 2522085) describes a method of removing the core from the mold without damaging it by using a drum-shaped core having a tapered surface at the boundary between the winding core and the flange. Patent Document 2 (JP Patent Publication 2019-57608) describes a drum-shaped core in which the flange surface to which the plate-shaped core is bonded has a convex curved shape. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Utility Model Registration No. 2522085 [Patent Document 2] JP 2019-57608 A Summary of the Invention [Problem to be solved by the invention]

[0005] The drum-shaped core is manufactured by feeding, for example, ferrite powder into a die, pressing it to form it, and then removing it from the die and sintering it. However, since the side of the compact is attached to the die, cracks may occur on the side of the flange of the compact when the compact is forcibly removed from the die. Such damage reduces the reliability of the drum-shaped core. In addition, this leads to the problem of reduced yield in the manufacturing process. [Means for solving the problem]

[0006] In one embodiment, a drum-shaped core has a pair of flange portions and a winding core portion extending in a first direction between the pair of flange portions and connecting the pair of flange portions to each other, the flange portions having a first main surface that extends in a planar view along the first direction and a second direction perpendicular to the first direction, and a second main surface opposite the first main surface, the side surfaces of the flange portions in the second direction have a first side surface and a second side surface connected to the first side surface and located closer to the first main surface than the first side surface, each of the first side surface and the second side surface has an inclination with respect to a third direction perpendicular to each of the first direction and the second direction, and the inclination angle of the second side surface with respect to the third direction is greater than the inclination angle of the first side surface with respect to the third direction. Effect of the Invention

[0007] According to one embodiment, it is possible to suppress the occurrence of cracks on the side surface of the flange portion. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a perspective view showing a drum-shaped core according to the embodiment. [Diagram 2] 1 is a perspective view showing a configuration in which a wire is wound around a drum-shaped core and a plate-shaped core is further bonded to the drum-shaped core in an embodiment. FIG. [Diagram 3] FIG. 4 is a side view showing a flange portion of the drum-shaped core according to the embodiment. [Figure 4] 4 is an enlarged side view showing a part of a flange portion of a drum-shaped core and a plate-shaped core facing the flange portion in the embodiment. FIG. [Diagram 5] 5A to 5C are cross-sectional views showing a manufacturing process of the drum-shaped core in the embodiment. [Figure 6] 10A to 10C are plan views showing a plurality of examples of the flange portion of the drum-shaped core in the first modified example of the embodiment. [Figure 7] FIG. 11 is a perspective view showing a drum-shaped core in a second modified example of the embodiment. [Figure 8] FIG. 11 is a perspective view showing a drum-shaped core in a third modified example of the embodiment. [Figure 9] FIG. 4 is a side view showing a drum-shaped core and a plate-shaped core in a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In all the drawings for explaining the embodiments, the same members are generally designated by the same reference numerals, and the repeated explanations thereof will be omitted. In addition, hatching may be applied even to plan views in order to make the drawings easier to understand.

[0010] (Embodiment 1) Below, we will explain how to provide a multi-stage tapered surface on the side of the flange portion of the drum-shaped core, and how to provide a flat surface on the convex portion of the surface of the flange portion of the drum-shaped core that is bonded to the plate-shaped core. (Embodiment) <Drum-shaped core configuration> Fig. 1 is a perspective view showing a drum-shaped core 1 in this embodiment. As shown in Fig. 1, the drum-shaped core 1 includes a winding core portion (column portion) 3 extending in the Y direction, and a pair of flange portions 2 provided in contact with both ends of the winding core portion 3 in the Y direction. In other words, the drum-shaped core 1 includes a pair of flange portions 2 and the winding core portion 3 extending in the Y direction between the pair of flange portions 2. Both ends of the winding core portion 3 in the Y direction are connected to the side surfaces of the pair of flange portions 2, respectively.

[0011] The drum-shaped core 2 is made of an electrically insulating material, more specifically, a magnetic material such as soft ferrite such as NiZn ferrite, a metal amorphous material, or a resin containing magnetic powder. The winding core 3 has, for example, a substantially rectangular cross-sectional shape, and is a rectangular prism extending in the Y direction (first direction). However, as described later, the side surface of the winding core 3 in the X direction (second direction) has a two-stage taper, and the cross section is not a perfect rectangle but is closer to a trapezoid. In other words, the width of the main surface 21 in the X direction is smaller than the width of the main surface 22 in the X direction. The X direction and the Y direction are perpendicular to each other in a plan view. The Z direction (height direction, third direction) is perpendicular to each of the X direction and the Y direction.

[0012] The flange portion 2 has a main surface (first main surface) 21 which is the upper surface, and a main surface (second main surface, top surface) 22 which is the lower surface opposite to the main surface 21. The main surface 21 is a surface along the X direction and the Y direction. The side surfaces on both sides of the flange portion 2 in the Y direction, which are side surfaces connecting the main surface 21 and the main surface 22, are along the Z direction. In contrast, the side surfaces on both sides of the flange portion 2 in the X direction have a taper (slope) with respect to the Z direction (direction perpendicular to the main surface 21). Each of the side surfaces of the flange portion 2 in the X direction has a two-stage taper between the main surface 22 and the main surface 21. Therefore, the width of the flange portion 2 in the X direction gradually decreases from the main surface 22 side toward the main surface 21 side. In a plan view, that is, when looking down on the drum-shaped core 1 from the main surface 21 side in the Z direction, all the side surfaces of the flange portion 2 in the X direction are arranged (see FIG. 6). Each of the two side surfaces of the flange portion 2 in the X direction is composed of a side surface (first side surface) 2a on the main surface 22 side and a side surface (second side surface) 2b located on the main surface 21 side of the side surface 2a, and the side surfaces 2a and 2b are connected to each other with a corner as a boundary. In this application, the plan view is a plan view from the Z direction, unless otherwise specified.

[0013] Similarly, the winding core 3 has a main surface (third main surface) 32 and a main surface opposite the main surface, and both side surfaces of the winding core 3 in the X direction have a two-stage taper. Therefore, the width of the winding core 3 in the X direction gradually decreases from the main surface 22 side toward the main surface 21 side. In a plan view, all of the side surfaces of the winding core 3 in the X direction are arranged. Each of the two side surfaces of the winding core 3 in the X direction is composed of a side surface (third side surface) 3a on the main surface 22 side and a side surface (fourth side surface) 3b on the main surface 21 side, and the side surfaces 3a, 3b are connected to each other with a corner as a boundary.

[0014] A protrusion (base) 4 is provided on the main surface 21 of the flange 2. The protrusion 4 has a substantially rectangular parallelepiped shape having a thickness in the Z direction. The upper surface of the protrusion 4 is along the main surface 21. The side surfaces of the protrusion 4 in the X direction and the Y direction are each along the Z direction, and a concave curved surface 4a that gently connects the side surface and the main surface 21 is provided at the boundary between the side surface and the main surface 21. Here, among the side surfaces of the flange 2 in the Y direction, the side surface opposite the winding core 3 and one side surface of the protrusion 4 are integrated, and they are continuous within one XZ plane. The drum-shaped core 1 constitutes a coil component, and is used with the main surface 21 side facing a substrate (not shown), and the protrusion 4 is used as a base (leg) facing the substrate.

[0015] The flange 2 has a protrusion 5 that protrudes downward (outside the flange 2) in the Z direction on the main surface 22 side. The lower surface of the protrusion 5 and the corner that is the boundary between the main surface 22 and the side surface 2a are connected by, for example, a gentle concave surface (concave curved surface).

[0016] The outer dimensions of the drum-shaped core 1 are, for example, 3.28 mm in the Y direction, 2.55 mm in the X direction, and 1.47 mm in the Z direction. The outer dimensions of the flange portion 2 are, for example, 0.66 mm in the Y direction. The dimensions of the winding core portion 3 are, for example, 1.96 mm in the Y direction, 1.14 mm in the X direction, and 0.84 mm in the Z direction.

[0017] The external dimensions of the protrusion 4 are, for example, 0.53 mm in the Y direction, 1.25 mm in the X direction, and 0.31 mm in the Z direction. The external dimensions of the protrusion 4 can also be, for example, 0.5 mm in the Y direction, 1.0 mm in the X direction, and 0.4 mm in the Z direction. The concave curved surface at the base of the protrusion 4 can be a concave curved surface with a radius of curvature R in the range of 0.05 μm or more and 0.2 μm or less, and here, for example, R=0.15 μm.

[0018] FIG. 2 shows a configuration in which a plate-shaped core (top plate) 30 is connected to a drum-shaped core 1, and a wire 6 is wound around a winding core 3. The drum-shaped core 1, the plate-shaped core 30, and the wire 6 constitute a coil component 10. The wire 6 is wound around the winding core 3 multiple times. One end of the wound wire is connected to, for example, a solder connected to a main surface 21 of one flange 2, although not shown here, and the other end of the wire is connected to a solder connected to a main surface 21 of the other flange 2. These solders are used as electrodes of the coil component 10. The wire 6 is made of, for example, a copper wire insulated with polyurethane or polyesterimide. The coil component 10 constitutes a closed ring-shaped magnetic circuit by the winding core 3, the flange 2, the plate-shaped core 30, and the flange 2, which are connected in sequence. The winding state of the wire 6 is not necessarily limited to the winding state shown in FIG. 2. For example, the wire 6 may be wound multiple times so as to fill the space between the winding core 3 and the plate-shaped core 30.

[0019] The upper surface of the plate core 30, i.e., the surface facing the main surface 22, is along the XY plane and is parallel to the lower surface (top surface) of the protrusion 5. The lower surface of the protrusion 5 and the upper surface of the plate core 30, and the concave surface and the upper surface of the plate core 30 are connected to each other by an adhesive 31. The drum-shaped core 1 and the plate core 30 are made of a magnetic material such as ferrite, a metallic amorphous material, or a resin containing magnetic powder.

[0020] Next, the shape of the flange portion 2 will be described with reference to Fig. 3. As shown in Fig. 3, the side surface of the flange portion 2 in the X direction has continuous side surfaces 2a and 2b. The side surface 2a is inclined at an angle θ1 with respect to the Z direction (vertical direction). The side surface 2b is inclined at an angle θ2 with respect to the Z direction. The relationship between the angles θ1 and θ2 is expressed as θ2>θ1. θ2 is, for example, in the range of 3 degrees or more and 10 degrees or less.

[0021] Similarly, the side surface in the X direction of the winding core portion 3 shown in Fig. 1 has a two-stage taper. The side surface is composed of side surfaces 3a and 3b connected to each other. Each of the side surfaces 3a and 3b has an inclination with respect to the Z direction, and the inclination angle of the side surface 3b with respect to the Z direction is larger than the inclination angle of the side surface 3a with respect to the Z direction.

[0022] As shown in FIG. 3, at a certain height, the distance between the side surfaces 2a in the X direction is w1, and at another height position, the distance between the side surfaces 2b in the X direction is w2. In this case, w1>w2. For example, the distance w1 is in the range of 2.46 mm or more and 2.55 mm or less, and the distance w2 is in the range of 2.30 mm or more and 2.50 mm or less. In the Z direction, the distance w1 is the width in the X direction at a position corresponding to 10% of the thickness t of the flange portion 2, and the distance w2 is the width in the X direction at a position corresponding to 90% of the thickness t of the flange portion 2.

[0023] In the Z direction, the dimensions of each of the side surfaces 2a and 2b are 0.4 mm or more and 0.8 mm or less. The dimensional ratio of the side surface 2b / the side surface 2a is, for example, 0.3 or more and 2 or less.

[0024] 1, the dimensions of each of the side surfaces 3a and 3b are 0.4 mm or more and 0.5 mm or less, and the dimensional ratio of the side surface 3b / the side surface 3a is, for example, 0.8 or more and 1.25 or less.

[0025] 4 shows an enlarged view of the lower end of the flange portion 2 on the main surface 22 side and the connection portion between the plate core 30 and the plate core 30. As shown in FIG. 4, the flange portion 2 has a top flat surface 5a (the lower surface of the protrusion 5 described above) and a concave inclined surface 5b (the concave surface described above) on the main surface 22 on the side to which the plate core 30 is bonded. That is, the main surface 22 includes the flat surface 5a, which is the surface of the protrusion 5, and the concave inclined surfaces 5b located on both sides of the flat surface 5a in the X direction. The flat surface 5a is a surface along the X direction and the Y direction, and is a surface that is connected in a state parallel to the upper surface of the plate core 30.

[0026] The height of the protrusion 5 in the Z direction is preferably in the range of 0 μm or more and 15 μm or less, for example, 5 μm. When the height of the protrusion 5 is in the above range, the distance between the main surface 22 other than the protrusion 5 and the plate-like core 30 is sufficiently close, so that the generation of leakage magnetic flux can be further suppressed. The height of the protrusion 5 here is the distance in the Z direction between the plane 5a, which is the lower surface of the protrusion 5, and the main surface 22 adjacent to the corner portion, which is the boundary between the main surface 22 and the side surface 2a. The dimension of the plane 5a in the X direction is preferably in the range of 200 μm or more and 700 μm or less, for example, 300 μm. The plane 5a is not limited to a perfect plane, but when the plane 5a is sandwiched between two imaginary planes parallel to the XY plane, the distance between the imaginary planes is 5 μm or less, preferably 3 μm or less, more preferably 1 μm or less, and particularly preferably zero. If the distance between the virtual surfaces is small in this way, there is substantially no magnetic gap between the plane 5a and the plate-shaped core 30. In addition, it is preferable that the plane 5a is provided at the center of the main surface 22 of the flange portion 2 in the X direction. More preferably, the winding core portion 3 is provided at the center of the flange portion 2 in the X direction. The concave inclined surface 5b is provided between the end of the plane 5a in the X direction and the corner portion. The concave inclined surface 5b is provided so as to be connected to each of both ends of the plane 5a in the X direction. The concave inclined surface 5b may be a plurality of planes having different inclination angles with respect to the Z direction connected and arranged continuously from the end of the plane 5a in the X direction to the corner portion of the plane 5a, or may be mainly composed of a concave curved surface.

[0027] <Effects of this embodiment> The drum-shaped core is manufactured by feeding, for example, ferrite powder into a die, pressing it to form it, and then removing it from the die and sintering it. However, since the side of the compact is attached to the die, cracks may occur on the side of the flange of the compact when the compact is forcibly removed from the die. Such damage causes a problem of reduced reliability of the drum-shaped core. In addition, in the manufacturing process, this leads to a problem of reduced yield of the drum-shaped core. Similarly, the problem of the compact being difficult to remove from the die may also occur near the side of the winding core 3.

[0028] Also, the main surface of the flange of the drum-shaped core, which is the surface to be bonded to the plate-shaped core, may be flat as a whole. However, in that case, the thickness of the adhesive between the drum-shaped core and the plate-shaped core is uniform. This uniform thickness of the adhesive becomes a magnetic gap, which causes a problem that leakage flux is likely to occur. That is, the performance of the drum-shaped core is deteriorated. Therefore, as shown in FIG. 9 as a comparative example of the drum-shaped core 11, it is possible to make the main surface 22x (the lower surface of the protrusion 5x) of the flange 2x on the plate-shaped core 30 side arc-shaped. However, in this comparative example, when the drum-shaped core 11 and the plate-shaped core 30 are bonded to each other, they come into line contact with each other, and the mutual arrangement cannot be stabilized, and the interval between the drum-shaped core 11 and the plate-shaped core 30 is likely to vary. In other words, the plate-shaped core 30 is likely to be bonded to the drum-shaped core 11 at an angle. Also, the gap between the drum-shaped core 11 and the plate-shaped core 30 is large except for the line contact portion, which causes a problem that leakage flux is likely to occur. That is, the performance of the drum-shaped core 11 is deteriorated.

[0029] Therefore, in this embodiment, the side surface of the flange portion 2 in the X direction is tapered in two stages (continuously tapered). This makes it possible to reduce the area of ​​contact between the side surface of the flange portion 2 and the die, and to prevent the side surface of the compact (drum-shaped core 1) from being stuck to the die. That is, the drum-shaped core of this embodiment is formed by pressing ferrite powder or the like from above and below using dies 25 and 26 as shown in FIG. 5. In FIG. 5, the outlines of the location where the winding core portion is formed and the convex portion of the die 26 located directly below the winding core portion are indicated by dashed lines.

[0030] Here, when the die 25 is released upward, the two-stage tapered side surfaces 2a, 2b (see FIG. 1) of the flange 2 allow the molded body to be easily removed from the die 25. This makes it easier to remove the molded body of the drum-shaped core 1 from the dies 25, 26, and inhibits cracks from occurring on the side surfaces of the flange 2 of the molded body. This prevents the reliability and performance of the drum-shaped core from deteriorating.

[0031] Similarly, the side of the winding core 3 in the X direction is tapered in two stages (continuous taper). This reduces the area of ​​contact between the side of the winding core 3 and the die, and prevents the side of the compact (drum-shaped core 1) from adhering to the die. The two-stage tapered sides 3a, 3b (see FIG. 1) of the winding core 3 allow the compact to be easily removed from the die 25. This makes it easier to remove the compact of the drum-shaped core 1 from the dies 25, 26, and prevents cracks from occurring in the side of the winding core 3 of the compact. This prevents the reliability and performance of the drum-shaped core from deteriorating.

[0032] Furthermore, by forming the connection between the protrusion 4 and the main surface 21 into a shape having a slope such as a gently sloping concave surface (concave surface 4a), the molded body can be easily removed from the die 25.

[0033] In addition, a convex portion 5 is provided on the main surface 22 of the flange portion 2. The main surface 22 has a plane 5a which is a flat surface, and the other area is configured by a concave inclined surface 5b, so that the gap of the adhesive surface between the drum-shaped core 1 and the plate-shaped core 30 can be reduced. Therefore, the generation of leakage magnetic flux can be prevented. In addition, since the plane 5a of the maximum convex portion abuts against the upper surface of the plate-shaped core 30, the arrangement of the plate-shaped core 30 can be more stable than the arc-shaped main surface 22x of the drum-shaped core 11 of the comparative example. Preferably, in the X direction, the plane 5a is provided in the center of the main surface 22 of the flange portion 2. More preferably, in the X direction, the winding core portion 3 is provided in the center of the flange portion 2. At this time, by reducing the gap of the contact surface between the drum-shaped core 1 and the plate-shaped core 30 near the center in the X direction, the generation of leakage magnetic flux can be further prevented.

[0034] <Variation 1> As this modified example, FIG. 6 shows several examples of the arrangement of the protrusions 4. In FIG. 6, four examples of the protrusions 4 are arranged from left to right. In the drum-shaped core 1 described with reference to FIG. 1 and FIG. 2, as shown in the leftmost part of FIG. 6, the positions of the protrusions 4 on the main surface 21 of the flange portion 2 are shifted toward the outer end of the drum-shaped core 1. In other words, in a plan view, a part of the protrusions 4 is in contact with an end portion of the main surface 21 in the Y direction that is opposite to the winding core portion 3 side. In addition, in a plan view, the protrusions 4 are spaced apart from an end portion of the main surface 21 in the Y direction that is on the winding core portion 3 side.

[0035] 6, the position of the protrusion 4 may be closer to the inner end of the drum-shaped core 1 (the winding core 3 side in plan view) on the main surface 21 of the flange portion 2. In other words, in plan view, a part of the protrusion 4 is in contact with the end of the main surface 21 in the Y direction that is on the winding core 3 side. Also, in plan view, the protrusion 4 is spaced apart from the end of the main surface 21 in the Y direction that is opposite to the winding core 3 side.

[0036] 6, the protrusion 4 may be spaced apart from both ends of the main surface 21 in the Y direction in plan view. In this case, the curved surface 4a is provided so as to annularly surround the periphery of the protrusion 4 in plan view.

[0037] 6, the width of the protrusion 4 in the Y direction may be the same as the width of the main surface 21 of the flange portion 2 in the Y direction. In this case, in a plan view, the protrusion 4 is formed from one end to the other end of the main surface 21 in the Y direction. In this case, the curved surface 4a is provided only in the vicinity of the side surface of the protrusion 4 in the X direction.

[0038] <Variation 2> 7, a two-stage taper may also be provided on the side surface in the Y direction of the flange portion 2. That is, of both side surfaces in the Y direction of the flange portion 2, the outer side surface of the drum-shaped core 1 (the side surface opposite the winding core portion 3) is composed of side surfaces 2c and 2d provided continuously in order from the main surface 22 side toward the main surface 21 side. The side surfaces 2c and 2d have a two-stage taper like the side surfaces 2a and 2b.

[0039] Of both side surfaces of the flange portion 2 in the Y direction, the side surface on the center side of the drum-shaped core 1 (the side surface on the winding core portion 3 side) is composed of side surfaces 2e and 2f provided continuously in sequence from the main surface 22 side toward the main surface 21 side. The side surfaces 2e and 2f have a two-stage taper, similar to the side surfaces 2a and 2b.

[0040] In this modified example, the flange portion 2 has a two-stage taper not only on the side surface in the X direction but also on the side surface in the Y direction, which makes it easier to remove from the mold.

[0041] <Modification 3> 8, a concave curved surface 3c may be provided that gently connects the boundary between the main surface (third main surface) 32 of the winding core portion 3 and the side surface of the flange portion 2. This makes it easier to remove the molded body from the die 25. The main surface 32 of the winding core portion 3 here refers to the surface located on the main surface 21 side of the two surfaces of the winding core portion 3 that are opposite to each other in the Z direction.

[0042] <Modification 4> In the present invention, the description has focused on a two-step taper, but the taper may be a three-step taper or a four-step taper. Also, the boundaries between the tapers do not necessarily have to be strictly angular, and may be chamfered.

[0043] Although the present invention has been specifically described based on the embodiments thereof, it goes without saying that the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the invention. For example, the first, second, third, and fourth modifications may be combined with each other. [Explanation of symbols]

[0044] 1, 11 Drum-shaped core 2, 2x Tsuba 2a, 2b, 2c, 2d, 2e, 2f, 3a, 3b side 3. Winding core 3c, 4a concave surface 4 Protrusion 5, 5x protrusion 5a plane 5b Concave slope 6 Wire 10 Coil parts 21, 22, 22x, 32 main surface 25, 26 Mold 30 Plate core 31 Adhesive

Claims

1. A pair of flanges; a winding core portion extending in a first direction between the pair of flange portions and connecting the pair of flange portions to each other; having The flange portion includes a first main surface along the first direction and a second direction perpendicular to the first direction in a plan view, and a second main surface opposite to the first main surface, a side surface of the flange portion in the second direction includes a first side surface and a second side surface connected to the first side surface and located closer to the first main surface than the first side surface; each of the first side surface and the second side surface has an inclination with respect to a third direction perpendicular to each of the first direction and the second direction; A drum-shaped core, wherein an inclination angle of the second side surface with respect to the third direction is greater than an inclination angle of the first side surface with respect to the third direction.

2. A pair of flanges; a winding core portion extending in a first direction between the pair of flange portions and connecting the pair of flange portions to each other; having the flange portion includes a first main surface along the first direction and a second direction perpendicular to the first direction in a plan view from a third direction perpendicular to the first direction, and a second main surface opposite to the first main surface; a side surface of the flange portion in the second direction includes a first side surface and a second side surface connected to the first side surface and located closer to the first main surface than the first side surface; each of the first side surface and the second side surface has an inclination with respect to the third direction perpendicular to each of the first direction and the second direction; A drum-shaped core, wherein a width of the first major surface is smaller than a width of the second major surface in the second direction.

3. The drum-shaped core according to claim 1 or 2, Further comprising a protrusion provided on the first main surface, A drum-shaped core, wherein a second side surface of the protrusion in the first direction or the second direction and the first main surface are connected by a concave curved surface.

4. The drum-shaped core according to claim 1 or 2, A side surface of the winding core portion in the second direction includes a third side surface and a fourth side surface connected to the third side surface and located closer to the first main surface than the third side surface in the third direction, each of the third side surface and the fourth side surface has an inclination with respect to the third direction; A drum-shaped core, wherein an inclination angle of the fourth side surface with respect to the third direction is greater than an inclination angle of the third side surface with respect to the third direction.

5. The drum-shaped core according to claim 1 or 2, The third main surface of the winding core portion and the flange portion are connected to each other by a concave curved surface, The third main surface is located on a side of the first main surface with respect to the winding core portion in the third direction.

6. A pair of flanges; a winding core portion extending in a first direction between the pair of flange portions and connecting the pair of flange portions to each other; having The flange portion includes a first main surface along the first direction and a second direction perpendicular to the first direction in a plan view, and a second main surface opposite to the first main surface, The second main surface is a surface to which a plate-like core is connected, the second main surface has a protrusion protruding outward from the flange portion in a third direction perpendicular to both the first direction and the second direction, A drum-shaped core, wherein the second main surface comprises a first plane which is the surface of the convex portion, and a concave inclined surface provided between an end of the first plane in the second direction and a corner which is the boundary between the second main surface and the side of the flange portion in the second direction.

7. The drum-shaped core according to claim 6, The first plane is connected to the plate-shaped core in a state parallel to a surface of the plate-shaped core.

8. The drum-shaped core according to claim 6, A drum-shaped core, wherein the concave inclined surface is connected to each of both end portions of the first plane in the second direction.

9. The drum-shaped core according to claim 6, The concave inclined surface is configured by connecting a plurality of flat surfaces each having a different inclination angle with respect to the third direction.

10. The drum-shaped core according to claim 6, The concave inclined surface has a concave curved surface.

11. The drum-shaped core according to claim 6, A drum-shaped core, wherein in a second direction, the first plane is provided at the center of the second main surface.

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