Ferrite core as well as coil component and electronic component that use the same

Abstract

To provide a ferrite core, as well as a coil component and an electronic component that use the ferrite core, which enable size and weight reduction.SOLUTION: A ferrite core 1 includes: a columnar center leg portion 40; first and second outer leg portions 52, 53 that are disposed on both sides of the center leg portion and spaced apart in a direction perpendicular to an axial direction of the center leg portion; a first connecting portion connecting the center leg portion and the first outer leg portion at their base portions; and a second connecting portion connecting the center leg portion and the second outer leg portion at their base portions. If the axial direction of the center leg portion is defined as a z-axis direction; a direction in which the first and second outer leg portions face each other perpendicular to the z-axis is defined as a y-axis direction; and a direction perpendicular to both y-axis and z-axis is defined as an x-axis direction, then the ferrite core viewed from above along the z-axis direction with the base portions of each leg located on the lower side is such that: an x-axis direction width w1 of the first outer leg portion is greater than an x-axis direction width w2 of the second outer leg portion; and a width d1 of the first outer leg portion along a straight line in the y-axis direction passing through the center of the center leg portion is smaller than a width d2 of the second outer leg portion along the straight line in the y-axis direction passing through the center of the center leg portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ferrite core used in various electronic devices, and to a coil component and an electronic component using the same. [Background technology]

[0002] Electric vehicles, including electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs), are rapidly gaining popularity in recent years. These vehicles are equipped with high-output electric motors and chargers, and their power supplies require coil components, such as transformers and choke windings, that can withstand high voltages and currents. These coil components generate heat due to resistance losses in the windings and magnetic energy losses in the ferrite core. The windings generate particularly significant heat. Therefore, they must be stabilized at a temperature slightly higher than the maximum temperature of the environment they are exposed to, preventing thermal runaway, which would cause the ferrite core to lose its magnetism, and preventing thermal damage to the windings themselves and the materials that make up the coil components.

[0003] A common method for dealing with heat generated by a coil component is to dissipate the heat to a heat sink that functions as a cooler, a frame with a large heat capacity, or the like via a mounting substrate, a metal case, or other mounting object. Japanese Patent Application Laid-Open Nos. 2013-131540 and 2015-141918 describe a method for dissipating heat generated by a coil component 201 by bringing a heat dissipation member (mounting object 300) into contact with a ferrite core 102, as shown in Fig. 9. The heat dissipation member is made of a metal member with high thermal conductivity, such as a copper plate or an aluminum plate. The so-called E-type ferrite core is known as a ferrite core used in coil components. (TDK Corporation, Mn-Zn ferrite core for switching power supplies, [searched February 15, 2018], Internet<URL: https: / / product.tdk.com / info / ja / catalog / datasheet / ferrite_mz_sw_e_ja.pdf> ). 10, the E-type ferrite core has a rectangular plate portion 160, a pair of outer legs 152, 153 protruding from both ends of the plate portion 160, and a center leg 140 provided therebetween. E-type ferrite core 101 is generally symmetrical, with outer legs 152, 153 provided at positions rotationally symmetrical about the center of center leg 140 standing in the center of plate portion 160. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-131540 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-141918 Summary of the Invention [Problem to be solved by the invention]

[0005] 9, contact between the coil component 201 and the mount object 300 on the back surface of the flat portion 160 of the ferrite core 102 is advantageous in that a wide contact area can be secured. However, because thermal gaps are formed in the heat paths in the radial and width directions (y-axis direction) of the winding 120 due to the insulator that protects the conductor wire, the heat conduction in the radial and width directions of the winding 120 is likely to be inferior to that in the circumferential direction of the winding.

[0006] Furthermore, since the coil component 201 is configured by combining a pair of ferrite cores 102, 102, a thermal gap 210 that reduces thermal conductivity at the combined surfaces is formed in the heat path (indicated by the arrow in the figure) between the ferrite cores 102, 102 when viewed from the mount body 300. As a result, heat dissipation from the winding and ferrite core farther from the mount body 300 in the y-axis direction tends to be insufficient, and it may be necessary to take additional measures to prevent thermal damage to the coil component.

[0007] Furthermore, as circuit boards become increasingly dense, there is a strong demand for smaller and lighter electronic components so that multiple electronic components can be densely arranged in a limited space, and also from the perspective of reducing battery consumption, which tends to limit the area in which individual electronic components can be arranged.When the ferrite core is made smaller to make coil components smaller and lighter, the amount of heat generated increases, and the contact area with the heat-dissipating material decreases, resulting in problems such as reduced heat dissipation performance.

[0008] Therefore, an object of the present invention is to provide a ferrite core that enables miniaturization and weight reduction, and a coil component and an electronic component that use the same. [Means for solving the problem]

[0009] That is, the ferrite core of the present invention is a ferrite core having a columnar center leg portion, a first outer leg portion and a second outer leg portion arranged spaced apart on both sides of the center leg portion in a direction perpendicular to the axial direction of the center leg portion, a first connecting portion connecting the center leg portion and the first outer leg portion at their bases, and a second connecting portion connecting the center leg portion and the second outer leg portion at their bases, When the axial direction of the center leg is defined as the z-axis direction, the opposing direction of the first outer leg and the second outer leg perpendicular to the z-axis is defined as the y-axis direction, and the direction perpendicular to the y-axis and z-axis is defined as the x-axis direction, and the ferrite core is viewed from above in the z-axis direction with the bases of the legs facing downward, a width w1 of the first outer leg in the x-axis direction is larger than a width w2 of the second outer leg in the x-axis direction, a width d1 of the first outer leg portion along a straight line in the y-axis direction that passes through the center of the middle leg portion is smaller than a width d2 of the second outer leg portion along a straight line in the y-axis direction that passes through the center of the middle leg portion; The ferrite core has a constriction that is continuous in the z-axis direction on both side surfaces of the center leg in the x-axis direction.

[0010] The center leg is preferably cylindrical.

[0011] In the ferrite core of the present invention, the first outer leg portion and the second outer leg portion have outer surfaces on the opposite side of the side facing the middle leg portion. It is preferable that the distance h1 from the central axis of the middle leg portion to the outer surface of the first outer leg portion and the distance h2 from the central axis of the middle leg portion to the outer surface of the second outer leg portion satisfy the relationship h1 < h2.

[0012] The ferrite core of the present invention is preferably symmetric with respect to the y-z plane passing through the central axis of the middle leg portion.

[0013] In the ferrite core of the present invention, it is preferable that the first outer leg portion and the second outer leg portion have arcuate inner surfaces on the side facing the middle leg portion.

[0014] In the ferrite core of the present invention, when measured along a straight line in the y-axis direction passing through the central axis of the middle leg portion, it is preferable that the distance from the central axis of the middle leg portion to the inner surface of the first outer leg portion is the same as the distance from the central axis of the middle leg portion to the inner surface of the second outer leg portion.

[0015] In the ferrite core of the present invention, it is preferable that the outer surface of the first outer leg portion is a flat surface.

[0016] In the ferrite core of the present invention, when viewed from the upper side in the z-axis direction, it is preferable that the area S1 of the end face in the z-axis direction of the first outer leg portion and the area S2 of the end face in the z-axis direction of the second outer leg portion are substantially the same. It is preferable that the area S1 and the area S2 satisfy the relationship S1 × 0.8 ≤ S2 ≤ S1 × 1.2.

[0017] The coil component of the present invention is a coil component including the ferrite core of the present invention and a winding disposed on the middle leg portion of the ferrite core.

[0018] In the coil component of the present invention, it is preferable to have a bobbin provided with a body portion into which the middle leg portions of a pair of the ferrite cores are inserted and around which the winding is wound.

[0019] In the coil component of the present invention, both ends of the winding are preferably drawn out to the second outer leg side of the ferrite core.

[0020] The electronic component of the present invention is an electronic component using the coil component of the present invention, The coil component is an electronic component in which the coil component is fixed to a metal support having a higher thermal conductivity than the ferrite core, with the outer surface of the first outer leg of the ferrite core in contact with or close to the support. In the electronic component of the present invention, it is preferable that the coil component is embedded in a resin containing a thermally conductive filler, and that the surface of the resin is exposed except for the surface in contact with the support. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a ferrite core that enables miniaturization and weight reduction, as well as a coil component and an electronic component that use the same. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a front view showing the structure of a ferrite core according to an embodiment of the present invention. [Figure 2] FIG. 2 is a front view showing the structure of a ferrite core with dimensions removed from FIG. 1. [Figure 3] FIG. 3 is a right side view of the ferrite core shown in FIG. 2. [Figure 4] FIG. 3 is a rear view of the ferrite core shown in FIG. 2. [Figure 5] FIG. 3 is a plan view of the ferrite core shown in FIG. 2. [Figure 6] FIG. 3 is a bottom view of the ferrite core shown in FIG. 2. [Figure 7] FIG. 3 is a perspective view of the ferrite core shown in FIG. 2. [Figure 8] 1 is a perspective view showing a state in which a coil component of the present invention, which is configured by combining ferrite magnetic cores according to an embodiment of the present invention, is placed on the surface of an object to be mounted. [Figure 9]FIG. 1 is a perspective view of a conventional coil component placed on the surface of an object to be mounted. [Figure 10] FIG. 1 is a front view showing an example of a conventional ferrite core. DETAILED DESCRIPTION OF THE INVENTION

[0023] Below, we will specifically explain a ferrite core according to one embodiment of the present invention, as well as coil components and electronic components using the same, but the present invention is not limited to these, and various modifications can of course be made within the scope of the present invention. Furthermore, the drawings used in the explanation mainly depict the essential parts to facilitate understanding of the gist of the invention, and omit details as appropriate. For the ferrite core, coil components, and electronic components of the present invention, parts having the same function are given the same numbers and symbols throughout the drawings.

[0024] [1] Ferrite core 1 to 8 show the structure of a ferrite core 1 according to one embodiment of the present invention. The ferrite core 1 of the present invention has a columnar center leg 40, a first outer leg 52 and a second outer leg 53 arranged on both sides of the center leg 40 at a distance in a direction perpendicular to the axial direction of the center leg 40, a first connecting portion 61 connecting the center leg 40 and the first outer leg 52 at their bases, and a second connecting portion 62 connecting the center leg 40 and the second outer leg 53 at their bases.

[0025] That is, the ferrite core 1 is configured such that the first outer leg 52, the middle leg 40, and the second outer leg 53, which are arranged in a row, are connected at their bases by the first connecting portion 61 and the second connecting portion 62, and protrude in the same direction. The first outer leg 52 and the second outer leg 53 are also referred to as a pair of outer legs.

[0026] The axial direction of the center leg 40 (the direction in which each leg protrudes) is the z-axis direction, the opposing direction between the first outer leg 52 and the second outer leg 53 perpendicular to the z-axis is the y-axis direction, and the direction perpendicular to the y-axis and z-axis is the x-axis direction. When the ferrite core 1 is viewed from above in the z-axis direction with the base of each leg (center leg 40, first outer leg 52, and second outer leg 53) facing downward, the first outer leg 52 and the second outer leg 53 have asymmetric shapes with different widths in the x-axis direction and different widths along a straight line in the y-axis direction passing through the center O of the center leg 40 (hereinafter, the "straight line in the y-axis direction passing through the central axis of the center leg 40" will also be simply referred to as the "straight line in the y-axis direction"). The width w1 of the first outer leg 52 in the x-axis direction is larger than the width w2 of the second outer leg 53 in the x-axis direction, and the width d1 of the first outer leg 52 along the straight line in the y-axis direction is smaller than the width d2 of the second outer leg 53 along the straight line in the y-axis direction. In the present invention, it is preferable that the shape of the center leg portion 40 when viewed in the z-axis direction (the shape when the ferrite core 1 is viewed from above in the z-axis direction with the base of each leg portion facing downward) is circular, i.e., the center leg portion 40 is cylindrical.

[0027] In the present application, the center O of the middle leg 40 is defined as the center of a circle circumscribing the shape of the middle leg as viewed in the z-axis direction. For example, if the shape of the middle leg as viewed in the z-axis direction is circular (i.e., the middle leg is cylindrical), the center of the circle is the center O. For example, if the shape of the middle leg as viewed in the z-axis direction is square (i.e., the middle leg is a regular rectangular prism), the intersection of the two diagonals of the square is the center O. The central axis of the middle leg is defined as the axis in the z-axis direction that passes through the center O of the middle leg.

[0028] An inner surface 52d1 of the first outer leg 52 facing the center leg 40 and an inner surface 53d of the second outer leg 53 facing the center leg 40 are arc-shaped curved surfaces so as to fit the outer shape of the winding 120, which is arranged in the center leg 40 and is formed by winding a conductor with a predetermined number of turns and winding diameter. When measured along a straight line in the y-axis direction, the distance from the central axis (center O) of the center leg 40 to the inner surface 52d1 of the first outer leg 52 is the same as the distance from the central axis (center O) of the center leg 40 to the inner surface 53d of the second outer leg 53.

[0029] The first outer leg portion 52 and the second outer leg portion 53 each have an outer surface 52c and an outer surface 53c on the side opposite to the side facing the middle leg portion 40 (the side of the inner surfaces 52d1 and 53d). The distance h1 from the central axis (center O) of the middle leg portion 40 to the outer surface 52c of the first outer leg portion 52 and the distance h2 from the central axis (center O) of the middle leg portion 40 to the outer surface 53c of the second outer leg portion 53 are in the relationship of h1 < h2. That is, the middle leg portion 40 is arranged at a position where the center O (central axis) is biased toward the first outer leg portion 52 with respect to the midpoint of the line segment connecting one end (outer surface 52c) and the other end (outer surface 53c) of the ferrite core 1 in the y-axis direction. The middle leg portion 40 only needs to have a cross-sectional area that does not cause magnetic saturation during use. In the illustrated example, the shape as viewed from the upper side in the z-axis direction is circular, but other shapes may also be used.

[0030] In the illustrated example, when viewed from the upper side in the z-axis direction, the area S1 of the end surface of the first outer leg portion 52 in the z-axis direction and the area S2 of the end surface of the second outer leg portion 53 in the z-axis direction are substantially the same, and the area S3 of the end surface of the middle leg portion 40 in the z-axis direction is substantially the same as the sum of the area S1 and the area S2. Since the middle leg portion 40 is a portion where the winding 120 is arranged and is likely to cause magnetic saturation, the area S3 may be set to be larger than the sum of the area S1 and the area S2. On the contrary, since leakage magnetic flux is likely to occur in the first outer leg portion 52 and the second outer leg portion 53, the area S3 of the middle leg portion 40 may be made smaller than the sum of the area S1 and the area S2. In that case, it is naturally necessary that the area S3 of the middle leg portion 40 is set so as not to cause magnetic saturation. Also, the area S1 and the area S2 may be made different as long as magnetic saturation is not caused, but it is desirable to make them the same in consideration of miniaturization of the ferrite core 1.

[0031] Here, "area S1 and area S2 are approximately the same" means that area S1 and area S2 are substantially the same, and similarly, "area S3 is approximately the same as the sum of area S1 and area S2" means that area S3 is substantially the same as the sum of area S1 and area S2. Specifically, area S1 and area S2 preferably satisfy the relationship S1×0.8≦S2≦S1×1.2, and more preferably satisfy the relationship S1×0.9≦S2≦S1×1.1. Area S3 and area S1+area S2 preferably satisfy the relationship (S1+S2)×0.8≦S3≦(S1+S2)×1.2, and more preferably satisfy the relationship (S1+S2)×0.9≦S3≦(S1+S2)×1.1.

[0032] The x-axis direction side surface of the ferrite core 1 has constrictions 71, 72 that are continuous with the side surface 40a of the center leg 40. The ferrite core 1 is usually formed by compressing ferrite granules and sintering the resulting compact. By providing the constrictions 71, 72, density differences that occur within the compact during molding can be reduced, thereby reducing deformation and cracks in the center leg 40 during sintering. The constrictions 71, 72 can also be used to position the bobbin to be combined with the ferrite core 1.

[0033] The side surface 62a of the second connecting portion 62 extending from the constrictions 71, 72 toward the second outer leg 53 is linear and parallel to the y-axis direction, and is continuous with the side surfaces 53a, 53b of the second outer leg 53 extending in the x-axis direction. Furthermore, the side surface 61a of the first connecting portion 61 extending toward the first outer leg 52 is inclined at a predetermined angle with respect to the y-axis direction so that the side facing the first outer leg 52 is wider.

[0034] At the portion where the first connecting portion 61 is wide and connects to the first outer leg portion 52, the width of the first outer leg portion 52 in the x-axis direction is larger than the width of the first connecting portion 61 in the x-axis direction, i.e., it protrudes in the x-axis direction with a step, forming surfaces 52d2 and 52d3 that connect the arc-shaped inner surface 52d1 of the first outer leg portion 52 to the side surfaces 52a and 52b in the x-axis direction.

[0035] The side surfaces of the first and second outer leg portions 52, 53, the side surface of the middle leg portion 40, and the side surfaces of the first and second connecting portions 61, 62 are all continuous from the upper end surface of each leg portion or connecting portion in the z-axis direction to the back surface 80.

[0036] In the illustrated example, the ferrite core 1 is symmetrical with respect to the yz plane passing through the central axis of the middle leg 40, i.e., in FIG. 1, it is symmetrical with respect to a line in the y-axis direction passing through the center O of the middle leg 40, but slight differences are acceptable.

[0037] The outer surface 52c of the first outer leg 52, the outer surface 53c of the second outer leg 53, and the back surface 80 (the back surfaces of the first and second outer legs 52, 53, the middle leg 40, and the first and second connecting portions 61, 62) are all flat surfaces. To facilitate release of the molded body from the mold during molding and to prevent chipping or damage at the corners, the edges of the back surface 80 are chamfered in a one-sided manner, and the corners of each portion are chamfered in a curved manner.

[0038] [2] Coil parts A coil component is formed by the ferrite core 1 of the present invention and the winding 120 placed on its center leg 40. FIG. 8 is a perspective view showing the appearance of the coil component 200. Preferably, the coil component 200 further includes a bobbin (not shown). The bobbin has a body portion into which the center leg 40 is inserted and around which the winding 120 is wound, and the center leg portions 40 of a pair of ferrite cores 1 are inserted into the body portion and combined to form the coil component 200. The coil component 200 is preferably fixed by applying tape (not shown) to the outer periphery of the combined ferrite cores 1, 1 or by adhesive.

[0039] The bobbin is preferably made of a resin having excellent insulating properties, heat resistance, and moldability, and is preferably made of polyphenylene sulfide, liquid crystal polymer, polyethylene terephthalate, polybutylene terephthalate, or the like, and can be molded by a known method such as injection molding.

[0040] The conductor used for the winding 120 is a coated wire with an insulating coating on a conductor made of a conductive material such as copper, aluminum, or an alloy thereof. Typically, an enameled wire with an insulating coating of polyamide-imide is used for the conductor, and a Litz wire made by twisting multiple enameled wires is preferably used. The number of turns of the winding 120 is set appropriately based on the required inductance, and the wire diameter can also be selected appropriately depending on the current being passed through.

[0041] The coil component 200 is used by bringing the outer surface 52c of the first outer leg 52 of the ferrite core 1,1 into contact with or close to a metal mount 300. The mount 300 can be made of a non-magnetic metal with excellent thermal conductivity, such as aluminum or its alloy, magnesium or its alloy, or copper or its alloy. To improve adhesion between the mount 300 and the ferrite core 1, a highly heat-resistant heat-dissipating grease may be applied.

[0042] 1 and 8, the height (dimension in the y-axis direction) of the coil component 200 is determined by the size of the ferrite core 1, and the width (dimension in the x-axis direction) of the coil component 200 is determined by the winding diameter of the winding 120. In the ferrite core 1 of the present invention, the width w1 in the x-axis direction of the first outer leg 52 is made larger than the width w2 in the x-axis direction of the second outer leg 53, without exceeding the outer shape of the winding 120, thereby increasing the opposing area with the mount body 300. Preferably, 1.2 × w2 ≦ w1, and more preferably 1.4 × w2 ≦ w1.

[0043] Then, the width d1 along the straight line in the y-axis direction of the first outer leg portion 52 is made smaller than the width d2 along the straight line in the y-axis direction of the second outer leg portion 53, and by making the width d1 of the first outer leg portion 52 thinner, the distance between the winding 120 and the mounted body 300 is reduced to shorten the heat path. Preferably, 0.3×d2≦d1≦0.7×d2, and more preferably, 0.4×d2≦d1≦0.6×d2. Also, by setting the relationship between the distance h1 from the central axis of the middle leg portion 40 to the outer side surface 52c of the first outer leg portion 52 and the distance h2 to the outer side surface 53c of the second outer leg portion 53 as h1 < h2, the middle leg portion 40 is disposed so as to be biased toward the first outer leg portion 52 side. Further, by making the area S1 of the end surface in the z-axis direction of the first outer leg portion 52 and the area S2 of the end surface in the z-axis direction of the second outer leg portion 53 substantially the same, the width H in the y-axis direction is made smaller than that of the conventional E-shaped ferrite core, thereby making the coil component 200 shorter in height.

[0044] Also, the position of the combined surface of the ferrite cores 1, 1 is set to avoid the position where a thermal gap 210 is formed in the middle of the conventional heat path.

[0045] According to such a configuration, the heat generated by the winding 120 can be efficiently released to the mounted body 300 through the ferrite core 1, and the heat generated by the winding 120 and the ferrite core 1 in the portion far from the mounted body 300 (the portion separated in the y-axis direction) can also be ensured to have heat dissipation performance through the heat path not passing through the thermal gap and the circumferential heat path of the winding 120 itself, so that it can be quickly released to the outside.

[0046] Also, by pulling out both ends (not shown) of the winding 120 to the second outer leg portion 53 side (the direction of arrow A in FIG. 8) of the ferrite cores 1, 1, the height defined by the ferrite cores 1, 1 can be reduced without increasing the dimension in the width direction of the coil component 200, so that the coil component 200 can be miniaturized.

[0047] [3] Electronic Components The coil component 200 is fixed to a metal mount 300 and embedded in a resin containing a thermally conductive filler to form an electronic component. The resin is preferably a silicone resin, and the thermally conductive filler is preferably selected from ceramics with excellent thermal conductivity, such as Al2O3, ZrO2, SiO2, Si3N4, and MgO. The amount of ceramic filler mixed into the silicone resin is desirably adjusted to achieve the desired heat dissipation, deformability, and strength. The resin containing the thermally conductive filler can further improve the heat dissipation of the coil component 200.

Claims

1. The columnar middle leg and a first outer leg portion and a second outer leg portion arranged on both sides of the middle leg portion at a distance in a direction perpendicular to the axial direction of the middle leg portion; a first connecting portion that connects the middle leg portion and the first outer leg portion at their base portions; a second connecting portion that connects the center leg portion and the second outer leg portion at their base portions, When the axial direction of the center leg is defined as the z-axis direction, the opposing direction of the first outer leg and the second outer leg perpendicular to the z-axis is defined as the y-axis direction, and the direction perpendicular to the y-axis and z-axis is defined as the x-axis direction, and the ferrite core is viewed from above in the z-axis direction with the bases of the legs facing downward, a width w1 of the first outer leg in the x-axis direction is larger than a width w2 of the second outer leg in the x-axis direction, a width d1 of the first outer leg portion along a straight line in the y-axis direction that passes through the center of the middle leg portion is smaller than a width d2 of the second outer leg portion along a straight line in the y-axis direction that passes through the center of the middle leg portion; The center leg portion has a constriction on each side surface in the x-axis direction that is continuous in the z-axis direction, Ferrite core obtained by sintering.

2. The ferrite core according to claim 1, At a portion where the first connecting portion is connected to the first outer leg, the width of the first outer leg in the x-axis direction is larger than the width of the first connecting portion in the x-axis direction; At a portion where the second connecting portion is connected to the second outer leg, the width of the second outer leg in the x-axis direction is equal to the width of the second connecting portion in the x-axis direction. Ferrite core.

3. The ferrite core according to claim 1 or 2, The middle leg is cylindrical. Ferrite core.

4. The ferrite core according to any one of claims 1 to 3, the first outer leg portion and the second outer leg portion have outer surfaces on the opposite sides facing the middle leg portion, a distance h1 from the central axis of the middle leg portion to the outer surface of the first outer leg portion and a distance h2 from the central axis of the middle leg portion to the outer surface of the second outer leg portion satisfy the relationship h1<h2; Ferrite core.

5. The ferrite core according to any one of claims 1 to 4, Symmetrical with respect to the yz plane passing through the central axis of the middle leg. Ferrite core.

6. The ferrite core according to any one of claims 1 to 5, The first outer leg portion and the second outer leg portion have an arc-shaped inner surface on the side facing the middle leg portion. Ferrite core.

7. The ferrite core according to claim 6, When measured along a straight line in the y-axis direction passing through the central axis of the middle leg portion, the distance from the central axis of the middle leg portion to the inner surface of the first outer leg portion is the same as the distance from the central axis of the middle leg portion to the inner surface of the second outer leg portion. Ferrite core.

8. The ferrite core according to any one of claims 1 to 7, The outer surface of the first outer leg portion is a flat surface. Ferrite core.

9. The ferrite core according to any one of claims 1 to 8, When viewed from above in the z-axis direction, an area S1 of an end face of the first outer leg in the z-axis direction and an area S2 of an end face of the second outer leg in the z-axis direction are substantially the same. Ferrite core.

10. The ferrite core according to claim 9, The area S1 and the area S2 are S1×0.8≦S2≦S1×1.2 Satisfy the relationship of Ferrite core.

11. A magnetic coil comprising the ferrite core according to any one of claims 1 to 10 and a winding disposed on the center leg portion of the ferrite core. Coil parts.

12. The coil component according to claim 11, a bobbin having a body portion into which the center legs of the pair of ferrite cores are inserted and on which a winding is wound; Coil parts.

13. The coil component according to claim 12, Both ends of the winding are drawn out to the second outer leg side of the ferrite core. Coil parts.

14. An electronic component using the coil component according to any one of claims 11 to 13, The coil component is fixed to a metal support having a higher thermal conductivity than the ferrite core, with the outer surface of the first outer leg of the ferrite core in contact with or close to the support. Electronic components.

15. The electronic component according to claim 14, Embedded in resin containing thermally conductive filler, Electronic components.

16. The electronic component according to claim 15, The surface of the resin is exposed except for the surface in contact with the object to be attached. Electronic components.

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