阅读说明：本技术 铁氧体磁芯、使用它的线圈部件以及电子部件 (Ferrite core, coil component using the same, and electronic component ) 是由 钱谷亮治 于 2019-02-22 设计创作，主要内容包括：本发明的铁氧体磁芯包括：柱状的中腿部；第一外腿部和第二外腿部,其在与中腿部的轴向正交的方向上以中腿部为中心隔开间隔地配置在两侧；第一连结部,其在中腿部和第一外腿部的根部连结中腿部与第一外腿部；和第二连结部,其在中腿部和第二外腿部的根部连结中腿部和第二外腿部,令中腿部的轴向为z轴方向,与z轴正交的第一外腿部和第二外腿部彼此相对的方向为y轴方向,与y轴和z轴正交的方向为x轴方向,在以各腿部的根部为下侧,从z轴方向的上侧观察铁氧体磁芯时,第一外腿部的x轴方向的宽度w1大于第二外腿部的x轴方向的宽度w2,第一外腿部的沿通过中腿部的中心的y轴方向的直线上的宽度d1小于第二外腿部的沿通过中腿部的中心的y轴方向的直线上的宽度d2。(The ferrite core of the present invention comprises: a columnar middle leg portion; first and second outer legs disposed on both sides of the center leg at a distance from each other in a direction orthogonal to the axial direction of the center leg; a first connecting portion connecting the middle leg portion and the first outer leg portion at the root portions of the middle leg portion and the first outer leg portion; and a second coupling portion that couples the middle leg portion and the second outer leg portion at the root portions of the middle leg portion and the second outer leg portion, wherein an axial direction of the middle leg portion is a z-axis direction, a direction in which the first outer leg portion and the second outer leg portion orthogonal to the z-axis face each other is a y-axis direction, a direction orthogonal to the y-axis and the z-axis is an x-axis direction, and a width w1 in the x-axis direction of the first outer leg portion is larger than a width w2 in the x-axis direction of the second outer leg portion when the ferrite core is viewed from an upper side in the z-axis direction with the root portions of the respective leg portions being lower sides, and a width d1 in a straight line of the first outer leg portion in the y-axis direction passing through the center of the middle leg portion is smaller than a width d2 in a straight line of the.)

1. A ferrite core, comprising:

a columnar middle leg portion;

first and second outer legs disposed on both sides of the center leg at a distance from each other in a direction orthogonal to the axial direction of the center leg;

a first connecting portion that connects the middle leg portion and the first outer leg portion at root portions of the middle leg portion and the first outer leg portion; and

a second joining portion joining the middle leg portion and the second outer leg portion at root portions thereof,

the axial direction of the middle leg is a z-axis direction, the direction in which the first outer leg and the second outer leg orthogonal to the z-axis face each other is a y-axis direction, the direction orthogonal to the y-axis and the z-axis is an x-axis direction, and when the ferrite core is viewed from the upper side in the z-axis direction with the root of each of the legs being the lower side,

the x-axis width w1 of the first outer leg is greater than the x-axis width w2 of the second outer leg,

a width d1 of the first outer leg along a line in a y-axis direction passing through a center of the center leg is less than a width d2 of the second outer leg along a line in a y-axis direction passing through a center of the center leg.

2. The ferrite core of claim 1, wherein:

the middle leg part is cylindrical.

3. The ferrite core according to claim 1 or 2, wherein:

the first and second outer legs have outer side faces on opposite sides of a side opposite the center leg,

a distance h1 from a central axis of the mid-leg to an outer side of the first outer leg and a distance h2 from the central axis of the mid-leg to an outer side of the second outer leg are in a relationship of h1 < h 2.

4. A ferrite core according to any of claims 1 to 3, wherein:

the ferrite core is of a symmetrical shape about a y-z plane passing through a central axis of the center leg.

5. A ferrite core according to any of claims 1 to 4, wherein:

the first outer leg and the second outer leg have arcuate inner side surfaces on a side opposite the center leg.

6. The ferrite core according to claim 5, wherein:

a distance from the central axis of the medial leg to the inner side of the first outer leg is the same as a distance from the central axis of the medial leg to the inner side of the second outer leg, as measured along a line in the y-axis direction passing through the central axis of the medial leg.

7. A ferrite core according to any of claims 1 to 6, wherein:

the outer side of the first outer leg is a flat surface.

8. A ferrite core according to any of claims 1 to 7, wherein:

an area S1 of the z-axis direction end surface of the first outer leg portion is substantially the same as an area S2 of the z-axis direction end surface of the second outer leg portion when viewed from the z-axis direction upper side.

9. The ferrite core of claim 8, wherein:

the area S1 and the area S2 satisfy the relation of S1 × 0.8 ≦ S2 ≦ S1 × 1.2.

10. A coil component characterized by:

having a ferrite core according to any one of claims 1 to 9 and a winding arranged on the mid-leg of the ferrite core.

11. The coil component of claim 10, wherein:

the ferrite core winding device comprises a winding frame, wherein the winding frame is provided with a main body part which can be inserted by the middle leg parts of a pair of ferrite cores and can be wound by a winding.

12. The coil component of claim 11, wherein:

both end portions of the winding are led out to the second outer leg portion side of the ferrite core.

13. An electronic component characterized by:

the coil component according to any one of claims 10 to 12,

the coil component is fixed to the body to be mounted made of metal so that an outer side surface of the first outer leg portion of the ferrite core comes into contact with or comes close to the body to be mounted, and is embedded in the body to be mounted using a resin containing a filler for heat conduction, wherein the body to be mounted has a higher heat conductivity than the ferrite core.

Technical Field

The present invention relates to a ferrite core used in various electronic devices, and a coil component and an electronic component using the ferrite core.

Background

Electric vehicles, which are one of electric transportation devices such as EVs (electric vehicles) and PHEVs (plug-in hybrid electric vehicles) that have rapidly become widespread in recent years, are equipped with devices such as high-output motors and chargers, and power supply devices used for these devices need to have coil components such as transformers and chokes that can withstand high voltage and large current, and electronic components using the coil components. The coil component generates heat due to resistance loss of the winding and magnetic energy loss of the ferrite core. In particular, the heat generation of the winding is significant. Therefore, it is necessary to stabilize the temperature at a temperature slightly higher than the maximum environmental temperature to be exposed, prevent thermal runaway in which the ferrite core loses magnetism, and prevent thermal damage to the winding itself and the members constituting the coil component.

As measures for preventing the coil component from generating heat, the following methods are generally used: heat is released to a heat sink serving as a cooler, a frame having a large heat capacity, or the like through a mounted body such as a mounted substrate or a metal case. Japanese patent laid-open nos. 2013-131540 and 2015-141918 describe heat dissipation of heat generated by the coil part 201 by bringing a heat dissipation member (mounted body 300) into contact with the ferrite core 102. The heat radiation member is made of a metal member having high thermal conductivity such as a copper plate or an aluminum plate.

As a ferrite core used for coil components, a so-called E-type ferrite core (TDK corporation, ferrite core for Mn — Zn switching power supply, search 2.15.2018, internet < URL: https:// product.tdk.com/info/ja/catalog/datasheet/transfer _ mz _ sw _ E _ ja.pdf >) is known. As shown in fig. 10, the E-type ferrite core has: a rectangular flat plate portion 160; a pair of outer leg portions 152 and 153 provided to protrude from both ends of the flat plate portion 160; and a middle leg 140 disposed therebetween. The E-type ferrite core 101 is generally of a symmetrical type in which outer leg portions 152, 153 are provided at positions rotationally symmetrical with respect to the center of the center leg portion 140 standing on the center of the flat plate portion 160.

Disclosure of Invention

Technical problem to be solved by the invention

As shown in fig. 9, on the back surface of the flat plate portion 160 of the ferrite core 102, it is advantageous to bring the coil component 201 into contact with the mounted body 300 because the contact area can be enlarged. However, since a thermal gap is formed on a thermal path in the radial and width directions (y-axis directions) of the winding 120 with the insulator protecting the wire, thermal conduction in the radial and width directions of the winding 120 easily becomes worse than thermal conduction in the circumferential direction around which it is wound.

Further, since the coil component 201 has a configuration in which the ferrite cores 102, 102 are combined into a pair, a thermal gap 210 in which thermal conductivity is reduced by the combined surfaces is formed on a thermal path (indicated by an arrow in the drawing) between the ferrite cores 102, 102 as viewed from the mounted body 300. Therefore, heat dissipation of the windings and the ferrite core on the side away from the mounted body 300 in the y-axis direction tends to be insufficient easily, and sometimes additional measures must be taken to prevent thermal damage to the coil component.

Further, as the density of circuit boards increases, in order to make it possible to densely arrange a plurality of electronic components in a limited space, and from the viewpoint of suppressing battery consumption, there is a strong demand for smaller and lighter electronic components, tending to limit the area in which each electronic component can be arranged. When the size of the ferrite core is reduced in order to reduce the size and weight of the coil component, the amount of heat generation increases and the contact area with the heat dissipation member decreases, which causes a problem of deterioration in heat dissipation performance.

Accordingly, an object of the present invention is to provide a ferrite core capable of reducing the size and weight of a coil component while considering heat dissipation, and a coil component and an electronic component using the ferrite core.

Means for solving the problems

Namely, the ferrite core of the present invention comprises:

a columnar middle leg portion;

first and second outer legs disposed on both sides of the center leg at a distance from each other in a direction orthogonal to the axial direction of the center leg;

a first connecting portion that connects the middle leg portion and the first outer leg portion at root portions of the middle leg portion and the first outer leg portion; and

a second joining portion joining the middle leg portion and the second outer leg portion at root portions thereof,

the axial direction of the middle leg is a z-axis direction, the direction in which the first outer leg and the second outer leg orthogonal to the z-axis face each other is a y-axis direction, the direction orthogonal to the y-axis and the z-axis is an x-axis direction, and when the ferrite core is viewed from the upper side in the z-axis direction with the root of each of the legs being the lower side,

the x-axis width w1 of the first outer leg is greater than the x-axis width w2 of the second outer leg,

a width d1 of the first outer leg along a line in a y-axis direction passing through a center of the center leg is less than a width d2 of the second outer leg along a line in a y-axis direction passing through a center of the center leg.

Preferably, the middle leg portion is cylindrical.

Preferably, in the ferrite core of the present invention, the first outer leg portion and the second outer leg portion have outer side surfaces on the opposite side to the side opposite to the center leg portion, and a distance h1 from a center axis of the center leg portion to the outer side surface of the first outer leg portion and a distance h2 from the center axis of the center leg portion to the outer side surface of the second outer leg portion have a relationship of h1 < h 2.

Preferably, the ferrite core of the present invention is of a symmetrical shape with respect to a y-z plane passing through a central axis of the center leg portion.

Preferably, in the ferrite core of the present invention, the first outer leg portion and the second outer leg portion have circular-arc inner side surfaces on a side opposite to the center leg portion.

Preferably, in the ferrite core of the present invention, a distance from the central axis of the center leg portion to the inner side surface of the first outer leg portion is the same as a distance from the central axis of the center leg portion to the inner side surface of the second outer leg portion, when measured along a straight line in the y-axis direction passing through the central axis of the center leg portion.

Preferably, in the ferrite core of the present invention, an outer side surface of the first outer leg portion is a flat surface.

Preferably, in the ferrite core of the present invention, an area S1 of the z-axis direction end surface of the first outer leg portion is substantially the same as an area S2 of the z-axis direction end surface of the second outer leg portion when viewed from the z-axis direction upper side. Preferably, the area S1 and the area S2 satisfy the relationship S1 × 0.8 ≦ S2 ≦ S1 × 1.2.

The coil component of the present invention includes the ferrite core of the present invention and a winding disposed on the center leg portion of the ferrite core.

Preferably, the coil component of the present invention includes a bobbin having a main body portion into which the pair of middle leg portions of the ferrite core are inserted and around which a winding is wound.

Preferably, in the coil component of the present invention, both end portions of the winding are drawn out to the second outer leg portion side of the ferrite core.

The electronic component of the present invention uses the coil component of the present invention, wherein the coil component is fixed to a metal mounting object such that an outer side surface of the first outer leg portion of the ferrite core is in contact with or close to the mounting object, and is embedded in the mounting object using a resin containing a filler for heat conduction, and wherein the thermal conductivity of the mounting object is higher than that of the ferrite core.

Effects of the invention

According to the present invention, it is possible to provide a ferrite core capable of reducing the size and weight of a coil component while taking heat dissipation into consideration, and a coil component and an electronic component using the ferrite core.

Drawings

Fig. 1 is a front view showing the structure of a ferrite core according to an embodiment of the present invention.

Fig. 2 is a front view showing the structure of the ferrite core with dimensional marks removed from fig. 1.

Fig. 3 is a right side view of the ferrite core shown in fig. 2.

Fig. 4 is a rear view of the ferrite core shown in fig. 2.

Fig. 5 is a top view of the ferrite core shown in fig. 2.

Fig. 6 is a bottom view of the ferrite core shown in fig. 2.

Fig. 7 is a perspective view of the ferrite core shown in fig. 2.

Fig. 8 is a perspective view showing a state in which a coil component of the present invention configured by combining ferrite cores according to an embodiment of the present invention is arranged on a surface of a mounting object.

Fig. 9 is a perspective view of a conventional coil component arranged on a surface of a mounted body.

Fig. 10 is a front view showing an example of a conventional ferrite core.

Detailed Description

Hereinafter, a ferrite core, a coil component using the same, and an electronic component according to an embodiment of the present invention will be specifically described, but the present invention is not limited thereto, and various changes may of course be made without departing from the gist of the present invention. In the drawings for explanation, main parts are mainly described to facilitate understanding of the gist of the present invention, and details and the like are appropriately omitted. Regarding the ferrite core, the coil component and the electronic component of the present invention, the same reference numerals are given to the parts having the same functions throughout the drawings.

[1] Ferrite magnetic core

Fig. 1 to 8 show the structure of a ferrite core 1 according to an embodiment of the present invention. The ferrite core 1 of the present invention comprises: a columnar center leg portion 40; a first outer leg 52 and a second outer leg 53 arranged on both sides of the center leg 40 with a space therebetween in a direction orthogonal to the axial direction of the center leg 40; a first connecting portion 61 that connects the middle leg portion 40 and the first outer leg portion 52 at their roots; and a second joining portion 62 joining the middle leg portion 40 and the second outer leg portion 53 at their root portions.

That is, the ferrite core 1 is configured such that: the first outer leg portion 52, the middle leg portion 40, and the second outer leg portion 53 arranged in a line are connected at their base portions by the first connecting portion 61 and the second connecting portion 62, and protrude in the same direction. In addition, the first outer leg 52 and the second outer leg 53 are also referred to as a pair of outer legs.

When the ferrite core 1 is viewed from the upper side in the z-axis direction with the root of each leg (the middle leg 40, the first outer leg 52, and the second outer leg 53) being the lower side and the base of each leg (the middle leg 40, the first outer leg 52, and the second outer leg 53) being the z-axis direction, the direction in which the first outer leg 52 and the second outer leg 53 orthogonal to the z-axis oppose each other being the y-axis direction, the direction orthogonal to the y-axis and the z-axis being the x-axis direction, the first outer leg 52 and the second outer leg 53 being formed such that: widths in the x-axis direction are different, and asymmetric shapes in which widths of straight lines in the y-axis direction passing through the center O of the center leg portion 40 (hereinafter, "straight lines in the y-axis direction passing through the center axis of the center leg portion 40" will also be simply referred to as "straight lines in the y-axis direction") are different, the width w1 in the x-axis direction of the first outer leg portion 52 is larger than the width w2 in the x-axis direction of the second outer leg portion 53, and the width d1 in the y-axis direction of the first outer leg portion 52 is smaller than the width d2 in the y-axis direction of the second outer leg portion 53. In the present invention, it is preferable that the shape of the center leg portion 40 as viewed in the z-axis direction (the shape when the ferrite core 1 is viewed from the upper side in the z-axis direction with the root of each leg portion as the lower side) be circular, that is, the center leg portion 40 be cylindrical.

In the present application, the center O of the center leg portion 40 is defined as the center of a circle that circumscribes the shape of the center leg portion when viewed in the z-axis direction. For example, when the shape of the middle leg portion as viewed in the z-axis direction is a circle (i.e., the middle leg portion is cylindrical), the center of the circle is the center O. For example, when the shape of the middle leg portion as viewed in the z-axis direction is a square (that is, the middle leg portion has a regular quadrangular prism shape), the intersection of two diagonal lines of the square is the center O. The central axis of the center leg is defined as the axis in the z-axis direction passing through the center O of the center leg.

The inner side surface 52d1 of the first outer leg portion 52 on the side opposite to the middle leg portion 40 and the inner side surface 53d of the second outer leg portion 53 on the side opposite to the middle leg portion 40 are curved in an arc shape so as to follow the outer shape of the coil 120 formed by winding a wire around the middle leg portion 40 with a predetermined number of turns and a winding diameter. Further, the distance from the central axis (center O) of the center leg portion 40 to the inner side surface 52d1 of the first outer leg portion 52 when measured along a straight line in the y-axis direction is made the same as the distance from the central axis (center O) of the center leg portion 40 to the inner side surface 53d of the second outer leg portion 53.

The first and second outer legs 52, 53 have an outer side surface 52c and an outer side surface 53c, respectively, on the opposite side of the side opposite the center leg 40 (the side of the inner side surfaces 52d1, 53 d), and the relationship between the distance h1 from the center axis (center O) of the center leg 40 to the outer side surface 52c of the first outer leg 52 and the distance h2 from the center axis (center O) of the center leg 40 to the outer side surface of the second outer leg 53 is h1 < h 2. That is, the center O (central axis) of the center leg 40 is arranged closer to the first outer leg 52 than to the midpoint of the line segment connecting one end (outer side surface 52c) and the other end (outer side surface 53c) of the ferrite core 1 in the y-axis direction. The middle leg portion 40 may have a cross-sectional area that does not cause magnetic saturation during use, and in the illustrated example, the shape when viewed from the upper side in the z-axis direction is circular, but may have another shape.

In the illustrated example, when viewed from the upper side in the z-axis direction, the area S1 of the z-axis direction end surface of the first outer leg portion 52 is substantially the same as the area S2 of the z-axis direction end surface of the second outer leg portion 53, and the area S3 of the z-axis direction end surface of the middle leg portion 40 is substantially the same as the sum of the area S1 and the area S2. Since the center leg 40 is a portion where magnetic saturation is likely to occur due to the arrangement of the windings 120, the area S3 may be set larger than the sum of the areas S1 and S2, or since the first and second outer legs 52, 53 are likely to generate leakage magnetic flux, conversely the area S3 of the center leg 40 may be set smaller than the sum of the areas S1 and S2. In this case, the area S3 of the middle leg 40 needs to be set so that magnetic saturation does not occur. Further, the area S1 and the area S2 may be different as long as the setting is such that magnetic saturation does not occur, but it is desirable that the area S1 be the same as the area S2 in view of the miniaturization of the ferrite core 1.

Here, "the area S1 is substantially the same as the area S2" means that the area S1 is substantially the same as the area S2, and similarly, "the area S3 is substantially the same as the sum of the areas S1 and S2" means that the area S3 is substantially the same as the sum of the areas S1 and S2. Specifically, the area S1 and the 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. The area S3 and the area S1+ the area S2 preferably satisfy the relationship (S1+ S2). times.0.8. ltoreq.S 3. ltoreq.S 1+ S2. ltoreq.1.2, more preferably satisfy the relationship (S1+ S2). times.0.9. ltoreq.S 3. ltoreq.S 1+ S2. ltoreq.S 1.1.

The side surface of the ferrite core 1 in the x-axis direction has constricted portions 71 and 72 continuous with the side surface 40a of the center leg portion 40. The ferrite core 1 is generally obtained by compressing ferrite particles and sintering the molded body thereof, and by providing the constricted portions 71 and 72, the density difference in the molded body generated at the time of molding can be reduced, and the occurrence of deformation, cracking, and the like in the leg portion 40 during sintering can be reduced. Furthermore, the constricted portions 71, 72 can also be used for positioning of the bobbin in combination with the ferrite core 1.

The side surfaces 62a of the second coupling portion 62 extending from the constricted portions 71, 72 toward the second outer leg portion 53 are linear parallel to the y-axis direction and continuous with the side surfaces 53a, 53b of the second outer leg portion 53 in the x-axis direction. The side surface 61a of the first connecting portion 61 extending toward the first outer leg portion 52 is inclined at a predetermined angle with respect to the y-axis direction so as to have a wide width on the first outer leg portion 52 side.

In the portion where the first connecting portion 61 has a wide width and is connected 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, that is, it is protruded stepwise in the x-axis direction, and surfaces 52d2, 52d3 are formed that connect the circular arc-shaped inner side surface 52d1 of the first outer leg portion 52 and the side surfaces 52a, 52b in the x-axis direction.

The side surfaces of the first outer leg portion 52 and the second outer leg portion 53, the side surface of the middle leg portion 40, and the side surfaces of the first coupling portion 61 and the second coupling portion 62 extend continuously from the upper end surface side in the z-axis direction of each leg portion or each coupling portion to the back surface 80.

In the example shown in the drawings, the ferrite core 1 has a symmetrical shape with respect to a y-z plane passing through the center axis of the center leg portion 40, that is, a symmetrical shape with respect to a straight line in the y-axis direction passing through the center O of the center leg portion 40 in fig. 1, but there may be some differences.

The outer side surface 52c of the first outer leg portion 52, the outer side surface 53c of the second outer leg portion 53, and the back surface 80 (the back surfaces of the first outer leg portion 52, the second outer leg portion 53, the middle leg portion 40, and the first and second coupling portions 61, 62) are flat surfaces. In consideration of the fact that the molded article can be released from the mold during molding and the corner portions are prevented from being broken, a single-sided chamfer is provided at the end edge of the back surface 80, and a curved chamfer is provided at the corner portion of each portion.

[2] Coil component

The coil component is composed of the ferrite core 1 of the present invention and the winding 120 disposed on the leg portion 40 thereof. Fig. 8 is a perspective view showing an external appearance of coil component 200. The coil component 200 preferably further has a bobbin (not shown). The bobbin has a main body portion into which the center leg portion 40 is inserted and wound with the winding 120, and the coil component 200 is configured by inserting and combining the center leg portions 40 of the pair of ferrite cores 1 into the main body portion. In the coil component 200, it is preferable that a tape (not shown) is attached to the outer periphery of the combined ferrite cores 1 and 1 or fixed by adhesion.

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

The wire used for the winding 120 may be a covered wire in which an insulating coating film is provided on a conductor made of a conductive material such as copper, aluminum, or an alloy thereof. Generally, an enamel wire insulatively coated with polyamideimide is used as the wire, and a twisted wire formed by twisting a plurality of enamel wires is preferably used. The number of turns of the winding 120 may be appropriately set based on the required inductance, and the wire diameter may also be appropriately selected according to the current to be passed.

The coil component 200 is used by bringing the outer side surface 52c of the first outer leg 52 of the ferrite cores 1 and 1 into contact with or close to the metal body 300 to be mounted. As the mounted body 300, a nonmagnetic metal having excellent thermal conductivity, such as aluminum or an alloy thereof, magnesium or an alloy thereof, or copper or an alloy thereof, may be used. In order to improve the adhesion between the mounted body 300 and the ferrite core 1, a heat-dissipating grease having high heat resistance may be applied thereto.

As shown in fig. 1 and 8, the height (dimension in the y-axis direction) of coil component 200 is defined by the dimension of ferrite core 1, and the width (dimension in the x-axis direction) of coil component 200 is defined by the winding diameter of winding 120. In the ferrite core 1 of the present invention, the width w1 in the x-axis direction of the first outer leg portion 52 is made larger than the width w2 in the x-axis direction of the second outer leg portion 53 to the extent of not exceeding the outer shape of the winding 120, so as to increase the area opposing the mounted body 300. Preferably 1.2 xw 2 ≦ w1, more preferably 1.4 xw 2 ≦ w 1.

Further, the width d1 of the line along the y-axis direction of the first outer leg portion 52 is made smaller than the width d2 of the line along the y-axis direction of the second outer leg portion 53, and the width d1 of the first outer leg portion 52 is reduced to reduce the interval between the winding 120 and the mounted body 300, thereby shortening the thermal path. Preferably 0.3 × d2 ≦ d1 ≦ 0.7 × d2, and more preferably 0.4 × d2 ≦ d1 ≦ 0.6 × d 2. In addition, the center leg portion 40 is disposed to be offset to the first outer leg portion 52 side by setting the relationship of the distance h1 from the center axis of the center 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 to h1 < h 2. Further, by making the area S1 of the z-axis direction end face of the first outer leg portion 52 substantially the same as the area S2 of the z-axis direction end face of the second outer leg portion 53, the width H in the y-axis direction can be reduced as compared with the conventional E-type ferrite core, and thus the height of the coil component 200 can be made low.

The position of the joint surface of the ferrite cores 1 and 1 is set so as to avoid the position where the thermal gap 210 is formed in the middle of the conventional thermal path.

According to such a configuration, the heat of the winding 120 can be efficiently released to the mounted body 300 by the ferrite core 1, and the heat generated by the winding 120 and the ferrite core 1 in the portion (portion distant in the y-axis direction) distant from the mounted body 300 can also be ensured in heat dissipation by the heat path not interposing the thermal gap and the circumferential heat path of the winding 120 itself, and thus can be quickly released to the outside.

Further, by drawing both end portions (not shown) of the winding 120 to the second outer leg portions 53 side of the ferrite cores 1 and 1 (the direction of arrow a in fig. 8), the height defined by the ferrite cores 1 and 1 can be reduced without increasing the dimension of the coil component 200 in the width direction, and therefore, the coil component 200 can be downsized.

[3] Electronic component

The coil component 200 is fixed to a metal mounting object 300, and embedded with a resin containing a heat conductive filler to form an electronic component. The resin is preferably a silicone resin, and the heat conductive filler is preferably selected from Al₂O₃、ZrO₂、SiO₂、Si₃N₄And ceramics having excellent thermal conductivity such as MgO. The mixing amount of the ceramic filler with respect to the silicone resin is preferably adjusted in such a manner that desired heat dissipation, deformability, and strength can be obtained. The heat dissipation property of the coil component 200 can be further enhanced by the resin containing the heat conductive filler.