Inductor

Abstract

This inductor includes a magnetic body, a first conductor, and a second conductor. The magnetic body has a bottom face, a top face facing away from the bottom face, and side faces joining the bottom face and the top face. The first conductor has a first internal conductor that is provided inside the magnetic body and a first external conductor that is provided outside the magnetic body. The second conductor has a second internal conductor that is provided inside the magnetic body and a second external conductor that is provided outside the magnetic body. The first internal conductor and the second internal conductor overlap each other at least partially when viewed from a direction perpendicular to the bottom face. The width of the first internal conductor orthogonal to the extension direction of the first internal conductor and the width of the second internal conductor orthogonal to the extension direction of the second internal conductor are different from each other.

Description

inductor

[0001] The present disclosure relates to an inductor used in a power supply circuit or the like.

[0002] In recent years, large-scale integrated circuits such as CPUs have become increasingly low-voltage, with the current required by the elements reaching tens of amperes, creating a demand for compact, low-profile power supply circuits. Multiphase power supply systems have become mainstream to accommodate these higher currents, and coupling power supply systems have been used to support these systems.

[0003] As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

[0004] Patent No. 4547889

[0005] Conventional inductors have limitations in terms of miniaturization while improving the coupling coefficient.

[0006] An inductor according to one aspect of the present disclosure includes a magnetic body, a first conductor, and a second conductor, wherein the magnetic body has a bottom surface, a top surface facing away from the bottom surface, and a side surface connecting the bottom surface and the top surface, the first conductor has a first internal conductor provided inside the magnetic body and a first external conductor provided outside the magnetic body, the second conductor has a second internal conductor provided inside the magnetic body and a second external conductor provided outside the magnetic body, and the first internal conductor and the second conductor are electrically connected to each other. The internal conductors at least partially overlap each other when viewed from a direction perpendicular to the bottom surface, the first external conductor has a first extension portion connected to the first internal conductor at the side surface and extending toward the bottom surface, the second external conductor has a second extension portion connected to the second internal conductor at the side surface and extending toward the bottom surface, and the width of the first internal conductor perpendicular to the extension direction of the first internal conductor and the width of the second internal conductor perpendicular to the extension direction of the second internal conductor are different from each other.

[0007] According to the present disclosure, it is possible to reduce the size of an inductor while improving the coupling coefficient thereof.

[0008] FIG. 1 is a perspective view of an inductor according to a first embodiment. FIG. 2 is a perspective view showing a first conductor and a second conductor included in the inductor according to the first embodiment. FIG. 3 is a front view of the inductor according to the first embodiment. FIG. 4 is a side view of the inductor according to the first embodiment. FIG. 5 is a diagram showing an inductor of a reference example. FIG. 6 is a diagram showing a table indicating the coupling coefficient when the width of the second conductor is changed, as well as the self-inductance, DC resistance, etc. of the first conductor and the second conductor. FIG. 7 is a graph indicating the coupling coefficient when the width of the second conductor is changed, as well as the self-inductance, DC resistance, etc. of the first conductor and the second conductor. FIG. 8 is a diagram showing an example of an inductor having different heights. FIG. 9 is a diagram showing a table indicating the self-inductance, etc. of the first conductor and the second conductor when the height of the inductor is changed. FIG. 10 is a graph indicating the self-inductance, etc. of the first conductor and the second conductor when the height of the inductor is changed. FIG. 11 is a diagram showing an example of an inductor having different opposing ratios of the first lead portion and the second lead portion. FIG. 12 is a diagram showing a table illustrating the coupling coefficient when the facing ratio between the first and second lead portions is changed, as well as the self-inductance and DC resistance of the first and second conductors. FIG. 13 is a graph showing the coupling coefficient when the facing ratio between the first and second lead portions is changed, as well as the DC resistance of the first and second conductors. FIG. 14 is a flowchart showing a method for manufacturing the inductor according to the first embodiment. FIG. 15 is a perspective view of an inductor according to the second embodiment. FIG. 16 is a perspective view showing the first and second conductors included in the inductor of the second embodiment. FIG. 17 is a front view of the inductor according to the second embodiment. FIG. 18 is a side view of the inductor according to the second embodiment. FIG. 19 is a diagram showing a table illustrating the coupling coefficient when the width of the first conductor is changed, as well as the self-inductance and DC resistance of the first and second conductors. FIG. 20 is a graph showing the coupling coefficient when the width of the first conductor is changed, as well as the self-inductance and DC resistance of the first and second conductors. FIG. 21 is a diagram showing an example of inductors with different heights.Fig. 22 is a diagram showing a table indicating the self-inductance of the first conductor and the second conductor when the height of the inductor is changed. Fig. 23 is a graph indicating the self-inductance of the first conductor and the second conductor when the height of the inductor is changed. Fig. 24 is a diagram showing an example of an inductor having a different facing ratio between the first lead portion and the second lead portion. Fig. 25 is a diagram showing a table indicating the coupling coefficient, the self-inductance of the first conductor and the second conductor, the DC resistance, etc. when the facing ratio between the first lead portion and the second lead portion is changed. Fig. 26 is a graph indicating the coupling coefficient, the DC resistance of the first conductor and the second conductor when the facing ratio between the first lead portion and the second lead portion is changed.

[0009] The embodiments will be specifically described with reference to the drawings.

[0010] Note that the embodiments described below each illustrate a specific example of the present disclosure. The numerical values, shapes, materials, components, component placement positions, connection configurations, steps, and step sequences shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not recited in independent claims are described as optional components.

[0011] Furthermore, in this specification, terms indicating the relationship between elements, such as parallelism, terms indicating the shape of elements, such as rectangular parallelepiped, and numerical ranges are not expressions that only express a strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of a few percent.

[0012] In addition, each drawing is a schematic diagram in which emphasis, omission, or adjustment of proportions has been appropriately made to illustrate the present disclosure, and is not necessarily an exact illustration, and may differ from the actual shape, positional relationship, and proportion. In each drawing, the same reference numerals are used to denote substantially the same components, and duplicated explanations may be omitted or simplified.

[0013] Each figure also shows an X-axis, a Y-axis, and a Z-axis, which represent three mutually orthogonal directions, and these axes and the axial directions along these axes are used as necessary for explanation. Note that these axes are added for explanation purposes only and do not limit the direction or posture in which the inductor is used.

[0014] First Embodiment [Configuration of Inductor] The configuration of an inductor according to a first embodiment will be described with reference to FIGS. 1 to 4. FIG.

[0015] Fig. 1 is a perspective view of an inductor 1 according to a first embodiment. Fig. 2 is a perspective view showing a first conductor 21 and a second conductor 22 included in the inductor 1. Fig. 3 is a view of the inductor 1 as seen from the front. Fig. 4 is a view of the inductor 1 as seen from the side.

[0016] Note that in Fig. 2, the insulating coating 20i on the first outer conductor 41 and the second outer conductor 42 is omitted, and the insulating coating 20i is shown only on the first inner conductor 31 and the second inner conductor 32. Fig. 3 shows a cross section of the inductor 1 taken along line III-III in Fig. 1. Fig. 4 shows a cross section of the inductor 1 taken along line IV-IV in Fig. 1. Furthermore, hatching of the cross sections is omitted in Figs. 3 and 4.

[0017] The inductor 1 shown in Figures 1 to 4 is a transformer inductor including a magnetic body 10 and a pair of conductors. The magnetic body 10 and the pair of conductors are integrally molded by pressure. The pair of conductors is composed of a first conductor 21 and a second conductor 22. The first conductor 21 and the second conductor 22 are insulated from each other and face each other inside the magnetic body 10.

[0018] In the inductor 1 of this embodiment, the first conductor 21 and the second conductor 22 face each other outside the magnetic body 10, making it possible to improve the coupling coefficient between the first conductor 21 and the second conductor 22. Furthermore, in the inductor 1 of this embodiment, the width of the first conductor 21 and the width of the second conductor 22 inside the magnetic body 10 are different from each other, making it possible to improve the self-inductance of the first conductor 21 and the second conductor 22. This makes it possible to reduce the size of the magnetic body 10 and make the inductor 1 more compact.

[0019] Hereinafter, the inductor 1 including the magnetic body 10 and the pair of conductors may be referred to as a transformer-inductor 1. Each of the components included in the transformer-inductor 1 will be described below.

[0020] The magnetic body 10 is a dust core formed from a mixture of magnetic material powder and a binder. The magnetic body 10 may be formed using a magnetic material. The magnetic material may be ferrite, or other magnetic materials. The metal magnetic powder is a particulate material having a predetermined elemental composition, such as an Fe-Si-Al system, an Fe-Si system, an Fe-Si-Cr system, or an Fe-Si-Cr-B system. The binder is a resin material, such as a silicone resin, that can maintain a certain shape by binding the metal magnetic powder particles while insulating them from each other.

[0021] The magnetic body 10 is molded into any shape by die molding. The magnetic body 10 of this embodiment has a rectangular parallelepiped shape with an outer peripheral surface. For example, the magnetic body 10 has a dimension of 2.4 mm in the X-axis direction, a dimension of 2.8 mm in the Y-axis direction, and a dimension of 1.8 mm in the Z-axis direction. The dimensions of the magnetic body 10 are appropriately selected from the ranges of 1.2 mm to 4.8 mm in the X-axis direction, 1.4 mm to 5.6 mm in the Y-axis direction, and 0.9 mm to 3.6 mm in the Z-axis direction.

[0022] 1, the magnetic body 10 has a bottom surface 18, a top surface 19, and four side surfaces connecting the bottom surface 18 and the top surface 19. The four side surfaces are composed of a side surface 11a, a side surface 11b, a side surface 11c, and a side surface 11d. Hereinafter, the side surface 11a may be referred to as one side surface, and the side surface 11b may be referred to as the other side surface.

[0023] The bottom surface 18 is a surface having a flat portion. The top surface 19 and the side surfaces 11a to 11d are each flat. The bottom surface 18 and the top surface 19 are parallel to each other and are back-to-back with each other in the Z-axis direction. One side surface 11a and the other side surface 11b are back-to-back with each other in the X-axis direction. The side surfaces 11c and 11d are back-to-back with each other in the Y-axis direction.

[0024] The bottom surface 18 and the top surface 19 extend in directions that intersect with each other, specifically perpendicular to the sides 11a to 11d, while the side surfaces 11a and 11b extend in directions that intersect with each other, specifically perpendicular to the sides 11c and 11d.

[0025] Two recesses are provided in the bottom surface 18. Of the two recesses, recess 18a is provided in a corner portion connecting the bottom surface 18 and one of the side surfaces 11a, and the other recess 18b is provided in a corner portion connecting the bottom surface 18 and the other side surface 11b. In other words, one recess 18a is recessed from the bottom surface 18 toward the top surface 19 and from one side surface 11a toward the other side surface 11b. The other recess 18b is recessed from the bottom surface 18 toward the top surface 19 and from the other side surface 11b toward the one side surface 11a. Both end portions of the first conductor 21 and the second conductor 22 are folded and stored in recesses 18a and 18b.

[0026] Each of the first conductor 21 and the second conductor 22 is formed by a conductor plate 20c having an insulating coating 20i (see FIGS. 3 and 4). The conductor plate 20c is made of a metal material selected from metals such as copper, aluminum, silver, and gold, alloys containing one or more of these metals, and materials consisting of metals or alloys and other substances. The insulating coating 20i is formed on the surface of the conductor plate 20c. The insulating coating 20i is made of a resin material containing an inorganic filler such as silica or alumina, such as a polyimide resin material. For example, the thickness of the conductor plate 20c of the first conductor 21 is 0.12 mm, and the thickness of the conductor plate 20c of the second conductor 22 is 0.1 mm. In this embodiment, the thickness of the conductor plate 20c of the first conductor 21 is thicker than the thickness of the conductor plate 20c of the second conductor 22, but this is not limited to this, and the conductor plate 20c of the first conductor 21 and the conductor plate 20c of the second conductor 22 may be the same thickness, or the thickness of the conductor plate 20c of the second conductor 22 may be thicker than the thickness of the conductor plate 20c of the first conductor 21.

[0027] First, the first conductor 21 of the pair of conductors will be described. The first conductor 21 has a shape that is line-symmetrical with respect to the midline between the one side surface 11a and the other side surface 11b when viewed from a direction perpendicular to the top surface 19, and also has a shape that is line-symmetrical with respect to the midline between the one side surface 11a and the other side surface 11b when viewed from a direction perpendicular to the side surface 11c.

[0028] 2, the first conductor 21 has a first inner conductor 31 provided inside the magnetic body 10 and a first outer conductor 41 provided outside the magnetic body 10. The first inner conductor 31 and the first outer conductor 41 are formed by processing a single member made of the same material.

[0029] The first internal conductor 31 is a portion embedded in the magnetic body 10. The first internal conductor 31 has one end 31a connected to one side surface 11a and the other end 31b connected to the other side surface 11b. The first internal conductor 31 extends linearly along a direction perpendicular to the side surface 11a (or side surface 11b) of the magnetic body 10 and is disposed parallel to the bottom surface 18 (or top surface 19). The first internal conductor 31 has a rectangular cross section (transverse cross section) perpendicular to the extension direction, and its width dimension is greater than its thickness dimension. Note that the width in this embodiment refers to the length in a direction parallel to both the bottom surface 18 (or top surface 19) and the side surface 11a (or side surface 11b). The first internal conductor 31 is disposed closer to the bottom surface 18 than a second internal conductor 32 (described later). The width W1 of the first inner conductor 31 perpendicular to the direction in which the first inner conductor 31 extends is wider than the width W2 of the second inner conductor 32 perpendicular to the direction in which the second inner conductor 32 extends.

[0030] The first outer conductor 41 has a plurality of first lead portions 51 and a plurality of first terminal portions 61 .

[0031] The plurality of first terminals 61 include one first terminal 61 a and another first terminal 61 b. The first terminals 61 are connected to the circuit board via a joining material such as solder when the transformer-inductor 1 is mounted on the circuit board. The insulating film 20 i is removed from the first terminals 61, exposing the conductor plate 20 c.

[0032] The multiple first lead portions 51 include one first lead portion 51a and another first lead portion 51b. One first lead portion 51a connects the first internal conductor 31 to one first terminal portion 61a, and the other first lead portion 51b connects the first internal conductor 31 to the other first terminal portion 61b. The first lead portion 51 has an insulating coating 20i on its surface. The first internal conductor 31, one first lead portion 51a, and the other first lead portion 51b function as a first coil of the transformer inductor 1.

[0033] One of the first lead portions 51a is connected to one end 31a of the first internal conductor 31 at one side surface 11a of the magnetic body 10. The one of the first lead portions 51a is bent at a right angle to the first internal conductor 31 and extends along a direction perpendicular to the bottom surface 18, i.e., along one side surface 11a, toward the bottom surface 18. The one of the first lead portions 51a is disposed closer to one side surface 11a than one of the second lead portions 52a, which will be described later. The width (maximum width) W1 of the one of the first lead portions 51a is wider than the width (maximum width) W2 of the one of the second lead portions 52a. In this example, the width (maximum width) W1 of the one of the first lead portions 51a is the same as the width W1 of the first internal conductor 31, and the width (maximum width) W2 of the one of the second lead portions 52a is the same as the width W2 of the second internal conductor 32.

[0034] One of the first terminal portions 61a is connected to the end of one of the first lead portions 51a on the bottom surface 18 side. One of the first terminal portions 61a is formed by being bent relative to one of the first lead portions 51a. One of the first terminal portions 61a is bent to face the bottom surface 18, and at least a portion of it is housed in one of the recesses 18a. One of the first terminal portions 61a protrudes outward from the bottom surface 18 (in a direction away from the bottom surface 18), and protrudes from the bottom surface 18 by, for example, 0.1 mm.

[0035] The other first lead portion 51b is connected to the other end 31b of the first internal conductor 31 at the other side surface 11b of the magnetic body 10. The other first lead portion 51b is bent at a right angle to the first internal conductor 31 and extends toward the bottom surface 18 in a direction perpendicular to the bottom surface 18, i.e., along the other side surface 11b. The other first lead portion 51b is disposed closer to the other side surface 11b than the other second lead portion 52b, which will be described later. The width (maximum width) W1 of the other first lead portion 51b is wider than the width (maximum width) W2 of the other second lead portion 52b. In this example, the width (maximum width) W1 of the other first lead portion 51b is the same as the width W1 of the first internal conductor 31, and the width (maximum width) W2 of the other second lead portion 52b is the same as the width W2 of the second internal conductor 32.

[0036] The other first terminal 61b is connected to the end of the other first lead portion 51b on the bottom surface 18 side. The other first terminal 61b is formed by being bent relative to the other first lead portion 51b. The other first terminal 61b is bent to face the bottom surface 18, and at least a portion of it is housed in the other recess 18b. The other first terminal 61b protrudes outward from the bottom surface 18, for example, by 0.1 mm.

[0037] Next, the second conductor 22 will be described. The second conductor 22 also has a shape that is line-symmetrical with respect to the midline between the one side surface 11 a and the other side surface 11 b when viewed from a direction perpendicular to the top surface 19, and also has a shape that is line-symmetrical with respect to the midline between the one side surface 11 a and the other side surface 11 b when viewed from a direction perpendicular to the side surface 11 c.

[0038] 2, the second electrical conductor 22 has a second inner conductor 32 provided inside the magnetic body 10 and a second outer conductor 42 provided outside the magnetic body 10. The second inner conductor 32 and the second outer conductor 42 are formed by processing a single member made of the same material.

[0039] The second internal conductor 32 is a portion embedded in the magnetic body 10. The second internal conductor 32 has one end 32a connected to one side surface 11a and the other end 32b connected to the other side surface 11b. The second internal conductor 32 extends linearly along a direction perpendicular to the side surface 11a (or side surface 11b) of the magnetic body 10, and is disposed parallel to the bottom surface 18 (or top surface 19). The second internal conductor 32 has a rectangular cross section (transverse cross section) perpendicular to the extension direction, and its width dimension is greater than its thickness dimension.

[0040] The second internal conductor 32 is parallel to the first internal conductor 31 and extends in the same direction as the first internal conductor 31. The first internal conductor 31 and the second internal conductor 32 have the same length in the extension direction inside the magnetic body 10. The second internal conductor 32 is disposed closer to the top surface 19 than the first internal conductor 31.

[0041] The first internal conductor 31 and the second internal conductor 32 at least partially overlap each other when viewed from a direction perpendicular to the bottom surface 18 (or the top surface 19). Specifically, the conductive plate 20c included in the first internal conductor 31 and the conductive plate 20c included in the second internal conductor 32 at least partially face each other in the direction perpendicular to the bottom surface 18.

[0042] In this embodiment, the width W1 of the first inner conductor 31 and the width W2 of the second inner conductor 32 are different in length. Specifically, the width W2 of the second inner conductor 32 is narrower than the width W1 of the first inner conductor 31 (W2<W1), and the dimension of the width W2 is 0.45 to 0.82 times the dimension of the width W1. Furthermore, the cross-sectional area of ​​the transverse cross section of the second inner conductor 32 is smaller than the cross-sectional area of ​​the transverse cross section of the first inner conductor 31. When viewed from a direction perpendicular to the top surface 19, both ends of the second inner conductor 32 in the width direction are located inside both ends of the first inner conductor 31 in the width direction. In the width direction, the second inner conductor 32 is disposed in the center of the first inner conductor 31.

[0043] The opposing distance d0 (see FIGS. 3 and 4 ) between the conductive plates 20c included in the first internal conductor 31 and the conductive plates 20c included in the second internal conductor 32 is at least twice the thickness of the insulating coating 20i, for example, 20 μm to 50 μm. The distance d2 between the second internal conductor 32 and the top surface 19 and the distance d1 between the first internal conductor 31 and the bottom surface 18 are the same. The first internal conductor 31 and the second internal conductor 32 may be arranged so that the boundary between them is at a height position half the height of the magnetic body 10.

[0044] The second outer conductor 42 has a plurality of second lead portions 52 and a plurality of second terminal portions 62 .

[0045] The plurality of second terminals 62 include one second terminal 62 a and another second terminal 62 b. The second terminals 62 are connected to the circuit board via a joining material such as solder when the transformer-inductor 1 is mounted on the circuit board. The insulating film 20 i is removed from the second terminals 62, exposing the conductor plate 20 c.

[0046] The second lead portions 52 include one second lead portion 52a and another second lead portion 52b. One second lead portion 52a connects the second internal conductor 32 to one second terminal portion 62a, and the other second lead portion 52b connects the second internal conductor 32 to the other second terminal portion 62b. The second lead portions 52 have an insulating coating 20i on their surfaces. The second internal conductor 32, one second lead portion 52a, and the other second lead portion 52b function as a second coil of the transformer inductor 1.

[0047] The first second lead portion 52a is connected to one end 32a of the second internal conductor 32 at one side surface 11a of the magnetic body 10. The first second lead portion 52a is formed by being bent relative to the second internal conductor 32. Specifically, the first second lead portion 52a overhangs the first first lead portion 51a at one side surface 11a and is then bent toward the bottom surface 18, extending in a direction perpendicular to the bottom surface 18, i.e., along the one side surface 11a, toward the bottom surface 18. The first second lead portion 52a is disposed outward of the first first lead portion 51a. The width (maximum width) W2 of the first second lead portion 52a is narrower than the width (maximum width) W1 of the first first lead portion 51a, and the dimension of the width W2 of the first second lead portion 52a is 0.45 to 0.82 times the dimension of the width W1 of the first first lead portion 51a.

[0048] The first lead portion 51a and the second lead portion 52a at least partially overlap each other when viewed from a direction perpendicular to the side surface 11a. In other words, the first lead portion 51a and the second lead portion 52a at least partially face each other in a direction perpendicular to the side surface 11a. In the region where the first lead portion 51a and the second lead portion 52a face each other, the facing distance between the conductor plate 20c included in the first lead portion 51a and the conductor plate 20c included in the second lead portion 52a is at least twice the thickness of the insulating coating 20i, for example, 20 μm to 50 μm.

[0049] One second terminal portion 62a is connected to the end portion of one second lead portion 52a on the bottom surface 18 side. One second terminal portion 62a is formed by being bent relative to one second lead portion 52a. One second terminal portion 62a is bent to face the bottom surface 18, and at least a portion of it is housed in one recess 18a. One second terminal portion 62a protrudes outward from the bottom surface 18, for example, protruding 0.1 mm from the bottom surface 18. Note that one first terminal portion 61a and one second terminal portion 62a do not overlap each other when viewed from a direction perpendicular to the side surface 11a.

[0050] The other second lead portion 52b is connected to the other end 32b of the second internal conductor 32 at the other side surface 11b of the magnetic body 10. The other second lead portion 52b is formed by being bent relative to the second internal conductor 32. Specifically, the other second lead portion 52b overhangs the other second lead portion 52b at the other side surface 11b and is then bent toward the bottom surface 18, extending along a direction perpendicular to the bottom surface 18, i.e., along the other side surface 11b, toward the bottom surface 18. The other second lead portion 52b is disposed outward of the other first lead portion 51b. The width (maximum width) W2 of the other second lead portion 52b is narrower than the width (maximum width) W1 of the other first lead portion 51b, and the dimension of the width W2 of the other second lead portion 52b is 0.45 to 0.82 times the dimension of the width W1 of the other first lead portion 51b.

[0051] The other first lead portion 51b and the other second lead portion 52b at least partially overlap each other when viewed from a direction perpendicular to the other side surface 11b. In other words, the other first lead portion 51b and the other second lead portion 52b at least partially face each other in a direction perpendicular to the other side surface 11b. In the region where the other first lead portion 51b and the other second lead portion 52b face each other, the facing distance between the conductor plate 20c included in the other first lead portion 51b and the conductor plate 20c included in the other second lead portion 52b is at least twice the thickness of the insulating coating 20i, for example, 20 μm to 50 μm.

[0052] The other second terminal 62b is connected to the end of the other second lead-out portion 52b on the bottom surface 18 side. The other second terminal 62b is formed by being bent relative to the other second lead-out portion 52b. The other second terminal 62b is bent to face the bottom surface 18, and at least a portion of it is housed in the other recess 18b. The other second terminal 62b protrudes outward from the bottom surface 18, for example, protruding 0.1 mm from the bottom surface 18. Note that the other first terminal 61b and the other second terminal 62b do not overlap each other when viewed in a direction perpendicular to the side surface 11b.

[0053] As described above, in the transformer inductor 1 of this embodiment, the first lead portion 51 and the second lead portion 52 at least partially overlap each other when viewed from a direction perpendicular to the side surface 11 a. This allows the first lead portion 51 and the second lead portion 52 to be coupled to each other outside the magnetic body 10. This allows the coupling coefficient of the transformer inductor 1 to be improved.

[0054] Furthermore, in the transformer inductor 1 of this embodiment, the width W1 of the first inner conductor 31 and the width W2 of the second inner conductor 32 are different from each other. This configuration shortens the magnetic path length of the magnetic flux circulating around the first inner conductor 31 and the second inner conductor 32. This makes it possible to improve the self-inductance of the first conductor 21 and the second conductor 22 while maintaining a high coupling coefficient in the transformer inductor 1. This reduces the size of the magnetic body 10, thereby enabling the transformer inductor 1 to be miniaturized.

[0055] [Effects, etc.] The effects of the above-described transformer-inductor 1 will be described in comparison with a reference example, etc.

[0056] 5 is a diagram showing an inductor 901 of a reference example. Note that in the reference example, the insulating coating 20i is omitted from the illustration.

[0057] The inductor 901 of the reference example is a transformer inductor including a magnetic body 10 and a pair of conductors. The pair of conductors is composed of a first conductor 21 and a second conductor 22. In the inductor 901 of the reference example, the width of the first conductor 21 and the width of the second conductor 22 inside the magnetic body 10 are the same. Specifically, the width of the first inner conductor 31 and the width of the second inner conductor 32 are the same. Furthermore, the width of one first lead portion 51a and the width of one second lead portion 52a are the same, and the width of the other first lead portion 51b and the width of the other second lead portion 52b are the same.

[0058] First, the coupling coefficient, self-inductance, DC resistance, etc. of the transformer-inductor 1 when the width of the second conductor 22 is changed will be described.

[0059] Fig. 6 is a table showing the coupling coefficient k when the width of the second conductor 22 is changed, as well as the self-inductance L and DC resistance DCR of the first conductor 21 and the second conductor 22. Fig. 7 is a graph showing the coupling coefficient k when the width of the second conductor 22 is changed, as well as the self-inductance L and DC resistance DCR of the first conductor 21 and the second conductor 22. Note that Fig. 7 is a graph of some of the data shown in Fig. 6.

[0060] 6 shows the coupling coefficient k of the inductor, the DC resistance DCR, self-inductance L (self L), and short-circuit inductance Ls (short L) of the first conductor 21, and the DC resistance DCR, self-inductance L (self L), and short-circuit inductance Ls (short L) of the second conductor 22. The short-circuit inductance Ls is the value measured when the inductance of one coil is measured with the other coil shorted, and is also called leakage inductance.

[0061] The coupling coefficient k shown in FIG. 6 is derived from the following (Equation 1).

[0062] k=(1-Ls / L) １／２... (Equation 1) The coupling coefficient k shown in the figure is a value calculated using the self-inductance L and short-circuit inductance Ls of the first conductor 21. The coupling coefficient k is a value when the thickness of the insulating coating 20i is 15 μm. In this example, a high coupling coefficient k is obtained when the coupling coefficient k is 0.95 or higher. The facing ratio between the first lead portion 51 and the second lead portion 52 in the figure is 80%. The facing ratio will be described later.

[0063] 6 shows data obtained when the width of the first conductor 21 is fixed at 0.55 mm and the width of the second conductor 22 is narrowed in 0.1 mm increments from 0.55 mm to 0.25 mm. The case where the width of the second conductor 22 is 0.55 mm corresponds to the above-mentioned Reference Example, and the cases where the width of the second conductor 22 is 0.45 mm, 0.35 mm, and 0.25 mm correspond to Embodiment 1. The widths of the second conductor 22, 0.45 mm, 0.35 mm, and 0.25 mm, are 0.82 times, 0.64 times, and 0.45 times the width of the first conductor 21, 0.55 mm, respectively.

[0064] 6 and 7 , as the width of the second conductor 22 is changed from 0.55 mm to 0.25 mm, the self-inductance L of the first conductor 21 and the self-inductance L of the second conductor 22 increase. Meanwhile, although the coupling coefficient k decreases slightly, it remains high at 0.95 or higher. Furthermore, although the DC resistance DCR of the second conductor 22 increases, the DC resistance DCR of the first conductor 21 remains the same.

[0065] In this way, by making the width of the second conductor 22 narrower than the width of the first conductor 21, for example, by making the width dimension of the second conductor 22 0.45 to 0.82 times the width dimension of the first conductor 21, the self-inductance L can be increased while maintaining a high coupling coefficient k.

[0066] Next, the coupling coefficient, self-inductance, DC resistance, etc. of the transformer-inductor 1 when the height of the transformer-inductor 1 is changed will be described.

[0067] FIG. 8 is a diagram showing an example of an inductor 1 having different heights.

[0068] The height of the transformer inductor 1 changes depending on the height of the magnetic body 10, so an example in which the height of the transformer inductor 1 is changed by changing the height of the magnetic body 10 will be described below.

[0069] The height of the transformer inductor 1 shown in Figure 8(a) is 1.85 mm, and the height of the transformer inductor 1 shown in Figure 8(b) is 1.76 mm. The height of the transformer inductor 1 shown in Figure 8(b) is 4.9% shorter than that of the transformer inductor 1 shown in Figure 8(a).

[0070] Fig. 9 is a table showing the coupling coefficient k, the self-inductance L of the first conductor 21 and the second conductor 22, and the like when the height of the inductor 1 is changed. Fig. 10 is a graph showing the self-inductance L of the first conductor 21 and the second conductor 22 when the height of the inductor 1 is changed. Note that Fig. 10 is a graph of some of the data shown in Fig. 9.

[0071] 9 shows an inductor 901 of the reference example. In the inductor 901 of the reference example, the width of the second conductor 22 is 0.55 mm, and the height of the inductor is 1.85 mm.

[0072] The second and subsequent lines in Fig. 9 are an example of embodiment 1. Figs. 9 and 10 show data obtained when the width of the first conductor 21 is 0.55 mm, the width of the second conductor 22 is 0.35 mm, and the height of the transformer inductor 1 is changed from 1.85 mm to 1.66 mm. The height positions of the first inner conductor 31 and the second inner conductor 32 were adjusted so that the height of the magnetic body 10 was changed and the boundary surface between the first inner conductor 31 and the second inner conductor 32 was located at half the height of the magnetic body 10. In Fig. 9, the facing ratio between the first lead portion 51 and the second lead portion 52 is 80%.

[0073] As shown in Figures 9 and 10, the self-inductance L of the first conductor 21 and the self-inductance L of the second conductor 22 decrease as the height of the transformer inductor 1 is changed from 1.85 mm to 1.66 mm. However, in this example, even when the height of the transformer inductor 1 is reduced to 1.76 mm, the self-inductance L of the first conductor 21 is 21.25 nH, which is approximately the same as the self-inductance of the inductor 901 of the reference example (21.26 nH). In other words, by setting the width of the first conductor 21 to 0.55 mm and the width of the second conductor 22 to 0.35 mm, the self-inductance L can be increased, thereby achieving a self-inductance equivalent to that of the reference example even when the height of the transformer inductor 1 is reduced as described above. In this example, the height can be changed from that shown in Figure 8(a) to that shown in Figure 8(b), reducing the height of the transformer inductor 1 by 4.9%. This allows the transformer inductor 1 to be made smaller.

[0074] Next, the relationship between the coupling coefficient k and the facing ratio of the first lead section 51 and the second lead section 52 will be described.

[0075] FIG. 11 is a diagram showing an example of an inductor in which the facing ratios of the first lead portion 51 and the second lead portion 52 are different.

[0076] Fig. 11 shows the transformer inductor 1 as viewed from a direction perpendicular to the side surface 11b. While the figure shows the view from the side surface 11b, the view from the side surface 11a is similar. Fig. 11(a) shows an example where the facing ratio is 0%, (b) shows an example where the facing ratio is 40%, and (c) shows an example where the facing ratio is 80%. The facing ratio Ro is defined by the following (Equation 2).

[0077] Ro (%) = (Ho / H1) × 100 (Equation 2) H1: length of first lead portion 51 in a direction perpendicular to bottom surface 18 (length from top to bottom end) Ho: length of opposing relationship between first lead portion 51 and second lead portion 52 in a direction perpendicular to bottom surface 18 Fig. 12 is a table showing the coupling coefficient k, the self-inductance L, and the DC resistance DCR of first conductor 21 and second conductor 22 when the opposing ratio Ro of first lead portion 51 and second lead portion 52 is changed. Fig. 13 is a graph showing the coupling coefficient k and the DC resistance DCR of first conductor 21 and second conductor 22 when the opposing ratio Ro of first lead portion 51 and second lead portion 52 is changed. Note that Fig. 13 is a graph of some of the data shown in Fig. 12 .

[0078] 12 shows data obtained when the opposing ratio is changed from 0% to 80% with the width of the first conductor 21 set to 0.55 mm and the width of the second conductor 22 set to 0.35 mm. The height of the transformer inductor 1 is set to 1.85 mm.

[0079] 12 and 13, in the transformer inductor 1, the coupling coefficient k increases as the opposing ratio Ro increases. Specifically, the coupling coefficient k is 0.9519 when the opposing ratio Ro is 10%, and the coupling coefficient k is 0.9651 when the opposing ratio Ro is 80%, both of which are higher than 0.95.

[0080] In this way, by setting the facing ratio Ro to be 10% or more and 80% or less, the coupling coefficient k can be increased. Also, by setting the facing ratio Ro to be 10% or more and 80% or less, the direct current resistance DCR can be reduced.

[0081] Furthermore, by setting the facing ratio Ro to be 30% or more and 80% or less, the coupling coefficient k can be further increased. Furthermore, by setting the facing ratio Ro to be 30% or more, the short-circuit inductance Ls, which is leakage inductance, can be set to approximately 2 nH or less. The reason why the facing ratio Ro is set to be 80% or less is to avoid electrical contact with the opposing conductor when the transformer inductor 1 is mounted on a circuit board.

[0082] [Method of Manufacturing Inductor] A method of manufacturing the inductor 1 according to the first embodiment will be described.

[0083] FIG. 14 is a flowchart showing a method for manufacturing the inductor 1 according to the first embodiment.

[0084] As shown in FIG. 14, the method for manufacturing the inductor 1 includes a conductor forming step S110, a magnetic body forming step S130, and a bending step S150.

[0085] First, in the conductor forming step S110, the conductor plate 20c is formed by punching a metal plate. Then, an insulating film 20i is formed on the surface of the conductor plate 20c, and the insulating film 20i is removed from the portion that will become the first terminal portion 61 to expose the conductor plate 20c, thereby forming the first conductor 21.

[0086] Another conductive plate 20c is formed by punching out another metal plate. The insulating film 20i is then removed from the portion that will become the second terminal 62 to expose the conductive plate 20c, thereby forming the second conductor 22. The insulating film 20i is removed by, for example, laser processing.

[0087] Next, in the magnetic body forming step S130, the magnetic body 10 is press-molded together with the first conductor 21 and the second conductor 22. In this magnetic body forming step S130, the first conductor 21 and the second conductor 22 are stacked in the thickness direction, and a portion of the first conductor 21 and a portion of the second conductor 22 are placed in a mold and covered with a mixture containing magnetic material powder and a binder. The press molding is performed so that the other portion of the first conductor 21 and the other portion of the second conductor 22 are not covered with the mixture, thereby forming the magnetic body 10. The portion of the first conductor 21 embedded in the magnetic body 10 becomes the first inner conductor 31, and the other portion of the first conductor 21 not embedded in the magnetic body 10 becomes the first outer conductor 41. The portion of the second conductor 22 embedded in the magnetic body 10 becomes the second inner conductor 32, and the other portion of the second conductor 22 not embedded in the magnetic body 10 becomes the second outer conductor 42.

[0088] Next, in a bending step S150, the two first lead portions 51 of the first outer conductor 41 are bent, and the two first terminal portions 61 are also bent. The two second lead portions 52 of the second outer conductor 42 are bent, and the two second terminal portions 62 are also bent. Through these steps shown in FIG. 14 , the transformer inductor 1 is produced.

[0089] Although the above example shows the case where the insulating film 20i is removed in the conductor forming step S110, the present invention is not limited to this. For example, the insulating film 20i may not be removed in the conductor forming step S110, but may be removed after the first terminal portion 61 and the second terminal portion 62 are bent in the bending step S150. In this case, the insulating film 20i may be removed by polishing or the like only from the outward facing surfaces of the first terminal portion 61 and the second terminal portion 62 (the surfaces opposite to the surfaces facing the magnetic body 10).

[0090] Second Embodiment [Configuration of Inductor] The configuration of an inductor 1A according to a second embodiment will be described with reference to Fig. 15 to Fig. 18. In the second embodiment, an example will be described in which the width of the first conductor 21 is narrower than the width of the second conductor 22.

[0091] Fig. 15 is a perspective view of an inductor 1A according to embodiment 2. Fig. 16 is a perspective view showing a first conductor 21 and a second conductor 22 included in the inductor 1A. Fig. 17 is a view of the inductor 1A as seen from the front. Fig. 18 is a view of the inductor 1A as seen from the side.

[0092] In Fig. 16, the insulating coating 20i on the first outer conductor 41 and the second outer conductor 42 is omitted, and the insulating coating 20i is shown only on the first inner conductor 31 and the second inner conductor 32. Fig. 17 shows a cross section of the inductor 1A taken along line XVII-XVII in Fig. 15. Fig. 18 shows a cross section of the inductor 1A taken along line XVIII-XVIII in Fig. 15. Furthermore, hatching of the cross section is omitted in Figs. 17 and 18.

[0093] The inductor 1A shown in Figures 15 to 18 is a transformer inductor including a magnetic body 10 and a pair of conductors. The magnetic body 10 and the pair of conductors are integrally molded by pressure. The pair of conductors is composed of a first conductor 21 and a second conductor 22. The first conductor 21 and the second conductor 22 are insulated from each other and face each other inside the magnetic body 10.

[0094] In the inductor 1A of this embodiment, the first conductor 21 and the second conductor 22 face each other outside the magnetic body 10, making it possible to improve the coupling coefficient k between the first conductor 21 and the second conductor 22. Furthermore, in the inductor 1A of this embodiment, the width of the first conductor 21 and the width of the second conductor 22 inside the magnetic body 10 are different from each other, making it possible to improve the self-inductance L of the first conductor 21 and the second conductor 22. This makes it possible to reduce the size of the magnetic body 10 and miniaturize the inductor 1A.

[0095] Hereinafter, the inductor 1A including the magnetic body 10 and a pair of conductors may be referred to as a transformer inductor 1A. Each component of the transformer inductor 1A will be described below. Note that the configuration of the magnetic body 10 is the same as in the first embodiment, and therefore description thereof will be omitted.

[0096] Each of the first conductor 21 and the second conductor 22 is formed by a conductor plate 20c having an insulating coating 20i (see FIGS. 17 and 18 ). The conductor plate 20c is made of a metal material selected from metals such as copper, aluminum, silver, and gold, alloys containing one or more of these metals, and materials composed of metals or alloys and other substances. The insulating coating 20i is formed on the surface of the conductor plate 20c. The insulating coating 20i is made of a resin material containing an inorganic filler such as silica or alumina, such as a polyimide resin material. For example, the thickness of the conductor plate 20c of the first conductor 21 is 0.12 mm, and the thickness of the conductor plate 20c of the second conductor 22 is 0.1 mm. In this embodiment, the thickness of the conductor plate 20c of the first conductor 21 is thicker than the thickness of the conductor plate 20c of the second conductor 22, but this is not limited to this, and the conductor plate 20c of the first conductor 21 and the conductor plate 20c of the second conductor 22 may be the same thickness, or the thickness of the conductor plate 20c of the second conductor 22 may be thicker than the thickness of the conductor plate 20c of the first conductor 21.

[0097] First, the first conductor 21 of the pair of conductors will be described. The first conductor 21 has a shape that is line-symmetrical with respect to the midline between the one side surface 11a and the other side surface 11b when viewed from a direction perpendicular to the top surface 19, and also has a shape that is line-symmetrical with respect to the midline between the one side surface 11a and the other side surface 11b when viewed from a direction perpendicular to the side surface 11c.

[0098] 16 , the first conductor 21 has a first inner conductor 31 provided inside the magnetic body 10 and a first outer conductor 41 provided outside the magnetic body 10. The first inner conductor 31 and the first outer conductor 41 are formed by processing a single member made of the same material.

[0099] The first internal conductor 31 is a portion embedded in the magnetic body 10. The first internal conductor 31 has one end 31a connected to one side surface 11a and the other end 31b connected to the other side surface 11b. The first internal conductor 31 extends linearly along a direction perpendicular to the side surface 11a (or side surface 11b) of the magnetic body 10 and is disposed parallel to the bottom surface 18 (or top surface 19). The first internal conductor 31 has a rectangular cross section (transverse cross section) perpendicular to the extension direction, and its width dimension is greater than its thickness dimension. Note that the width in this embodiment refers to the length in a direction parallel to both the bottom surface 18 (or top surface 19) and the side surface 11a (or side surface 11b).

[0100] The first internal conductor 31 is parallel to the second internal conductor 32 and extends in the same direction as the second internal conductor 32. The first internal conductor 31 and the second internal conductor 32 have the same length in the extension direction inside the magnetic body 10. The first internal conductor 31 is disposed closer to the bottom surface 18 than the second internal conductor 32, which will be described later.

[0101] The first internal conductor 31 and the second internal conductor 32 at least partially overlap each other when viewed from a direction perpendicular to the bottom surface 18 (or the top surface 19). Specifically, the conductive plate 20c included in the first internal conductor 31 and the conductive plate 20c included in the second internal conductor 32 at least partially face each other in the direction perpendicular to the bottom surface 18.

[0102] In this embodiment, the width W1 of the first inner conductor 31 and the width W2 of the second inner conductor 32 are different in length. Specifically, the width W1 of the first inner conductor 31 is narrower than the width W2 of the second inner conductor 32 (W1<W2), and the dimension of the width W1 is 0.45 to 0.82 times the dimension of the width W2. Furthermore, the cross-sectional area of ​​the transverse cross section of the first inner conductor 31 is smaller than the cross-sectional area of ​​the transverse cross section of the second inner conductor 32. When viewed from a direction perpendicular to the bottom surface 18, both ends of the first inner conductor 31 in the width direction are located inside both ends of the second inner conductor 32 in the width direction. In the width direction, the first inner conductor 31 is disposed at the center of the second inner conductor 32.

[0103] The first outer conductor 41 has a plurality of first lead portions 51 and a plurality of first terminal portions 61 .

[0104] The plurality of first terminals 61 include one first terminal 61 a and another first terminal 61 b. When the transformer inductor 1A is mounted on a circuit board, the first terminals 61 are connected to the circuit board via a joining material such as solder. The insulating film 20 i of the first terminals 61 is removed, exposing the conductor plate 20 c.

[0105] The plurality of first lead portions 51 include one first lead portion 51a and another first lead portion 51b. One first lead portion 51a connects the first internal conductor 31 to one first terminal portion 61a, and the other first lead portion 51b connects the first internal conductor 31 to the other first terminal portion 61b. The first lead portion 51 has an insulating coating 20i on its surface. The first internal conductor 31, one first lead portion 51a, and the other first lead portion 51b function as a first coil of the transformer inductor 1A.

[0106] The first lead portion 51a is connected to one end 31a of the first internal conductor 31 at one side surface 11a of the magnetic body 10. The first lead portion 51a is bent at a right angle to the first internal conductor 31 and extends along a direction perpendicular to the bottom surface 18, i.e., along one side surface 11a, toward the bottom surface 18. The first lead portion 51a is disposed closer to one side surface 11a than a second lead portion 52a, which will be described later. The width (maximum width) W1 of the first lead portion 51a is narrower than the width (maximum width) W2 of the second lead portion 52a, and the dimension of the width W1 of the first lead portion 51a is 0.45 to 0.82 times the dimension of the width W2 of the second lead portion 52a. In this example, the width (maximum width) W1 of one of the first draw-out portions 51a is the same as the width W1 of the first internal conductor 31, and the width (maximum width) W2 of one of the second draw-out portions 52a is the same as the width W2 of the second internal conductor 32.

[0107] One of the first terminal portions 61a is connected to the end of one of the first lead portions 51a on the bottom surface 18 side. One of the first terminal portions 61a is formed by being bent relative to one of the first lead portions 51a. One of the first terminal portions 61a is bent to face the bottom surface 18, and at least a portion of it is housed in one of the recesses 18a. One of the first terminal portions 61a protrudes outward from the bottom surface 18 (in a direction away from the bottom surface 18), and protrudes from the bottom surface 18 by, for example, 0.1 mm.

[0108] The other first lead portion 51b is connected to the other end 31b of the first internal conductor 31 at the other side surface 11b of the magnetic body 10. The other first lead portion 51b is bent at a right angle to the first internal conductor 31 and extends along a direction perpendicular to the bottom surface 18, i.e., along the other side surface 11b, toward the bottom surface 18. The other first lead portion 51b is disposed closer to the other side surface 11b than the other second lead portion 52b, which will be described later. The width (maximum width) W1 of the other first lead portion 51b is narrower than the width (maximum width) W2 of the other second lead portion 52b, and the dimension of the width W1 of the other first lead portion 51b is 0.45 to 0.82 times the dimension of the width W2 of the other second lead portion 52b. In this example, the width (maximum width) W1 of the other first draw-out portion 51b is the same as the width W1 of the first internal conductor 31, and the width (maximum width) W2 of the other second draw-out portion 52b is the same as the width W2 of the second internal conductor 32.

[0109] The other first terminal 61b is connected to the end of the other first lead portion 51b on the bottom surface 18 side. The other first terminal 61b is formed by being bent relative to the other first lead portion 51b. The other first terminal 61b is bent to face the bottom surface 18, and at least a portion of it is housed in the other recess 18b. The other first terminal 61b protrudes outward from the bottom surface 18, for example, by 0.1 mm.

[0110] Next, the second conductor 22 will be described. The second conductor 22 also has a shape that is line-symmetrical with respect to the midline between the one side surface 11 a and the other side surface 11 b when viewed from a direction perpendicular to the top surface 19, and also has a shape that is line-symmetrical with respect to the midline between the one side surface 11 a and the other side surface 11 b when viewed from a direction perpendicular to the side surface 11 c.

[0111] 16 , the second electrical conductor 22 has a second inner conductor 32 provided inside the magnetic body 10 and a second outer conductor 42 provided outside the magnetic body 10. The second inner conductor 32 and the second outer conductor 42 are formed by processing a single member made of the same material.

[0112] The second internal conductor 32 is embedded in the magnetic body 10. The second internal conductor 32 has one end 32a connected to one side surface 11a and the other end 32b connected to the other side surface 11b. The second internal conductor 32 extends linearly in a direction perpendicular to the side surface 11a (or side surface 11b) of the magnetic body 10 and is disposed parallel to the bottom surface 18 (or top surface 19). The second internal conductor 32 has a rectangular cross section (transverse cross section) perpendicular to the extension direction, and its width dimension is greater than its thickness dimension. The second internal conductor 32 is disposed closer to the top surface 19 than the first internal conductor 31. A width W2 of the second internal conductor 32 perpendicular to the extension direction of the second internal conductor 32 is wider than a width W1 of the first internal conductor 31 perpendicular to the extension direction of the first internal conductor 31.

[0113] The opposing distance d0 (see FIGS. 17 and 18 ) between the conductive plates 20c included in the first internal conductor 31 and the conductive plates 20c included in the second internal conductor 32 is at least twice the thickness of the insulating coating 20i, for example, 20 μm to 50 μm. The distance d2 between the second internal conductor 32 and the top surface 19 is the same as the distance d1 between the first internal conductor 31 and the bottom surface 18. The first internal conductor 31 and the second internal conductor 32 may be arranged so that the boundary surface between them is at a height position half the height of the magnetic body 10.

[0114] The second outer conductor 42 has a plurality of second lead portions 52 and a plurality of second terminal portions 62 .

[0115] The plurality of second terminals 62 include one second terminal 62 a and another second terminal 62 b. When the transformer inductor 1A is mounted on a circuit board, the second terminals 62 are connected to the circuit board via a joining material such as solder. The insulating coating 20 i of the second terminals 62 is removed, exposing the conductive plate 20 c.

[0116] The second lead portions 52 include one second lead portion 52a and another second lead portion 52b. One second lead portion 52a connects the second internal conductor 32 to one second terminal portion 62a, and the other second lead portion 52b connects the second internal conductor 32 to the other second terminal portion 62b. The second lead portions 52 have an insulating coating 20i on their surfaces. The second internal conductor 32, one second lead portion 52a, and the other second lead portion 52b function as a second coil of the transformer inductor 1A.

[0117] The second lead portion 52a is connected to one end 32a of the second internal conductor 32 at one side surface 11a of the magnetic body 10. The second lead portion 52a is formed by being bent relative to the second internal conductor 32. Specifically, the second lead portion 52a overhangs the first lead portion 51a at one side surface 11a and is then bent toward the bottom surface 18, extending in a direction perpendicular to the bottom surface 18, i.e., along the one side surface 11a, toward the bottom surface 18. The second lead portion 52a is positioned outward of the first lead portion 51a. The width (maximum width) W2 of the second lead portion 52a is wider than the width (maximum width) W1 of the first lead portion 51a.

[0118] The first lead portion 51a and the second lead portion 52a at least partially overlap each other when viewed from a direction perpendicular to the side surface 11a. In other words, the first lead portion 51a and the second lead portion 52a at least partially face each other in a direction perpendicular to the side surface 11a. In the region where the first lead portion 51a and the second lead portion 52a face each other, the facing distance between the conductor plate 20c included in the first lead portion 51a and the conductor plate 20c included in the second lead portion 52a is at least twice the thickness of the insulating coating 20i, for example, 20 μm to 50 μm.

[0119] One second terminal portion 62a is connected to the end portion of one second lead portion 52a on the bottom surface 18 side. One second terminal portion 62a is formed by being bent relative to one second lead portion 52a. One second terminal portion 62a is bent to face the bottom surface 18, and at least a portion of it is housed in one recess 18a. One second terminal portion 62a protrudes outward from the bottom surface 18, for example, protruding 0.1 mm from the bottom surface 18. Note that one first terminal portion 61a and one second terminal portion 62a do not overlap each other when viewed from a direction perpendicular to the side surface 11a.

[0120] The other second lead portion 52b is connected to the other end 32b of the second internal conductor 32 at the other side surface 11b of the magnetic body 10. The other second lead portion 52b is formed by being bent relative to the second internal conductor 32. Specifically, the other second lead portion 52b overhangs the other second lead portion 52b at the other side surface 11b and is then bent toward the bottom surface 18, extending along a direction perpendicular to the bottom surface 18, i.e., along the other side surface 11b, toward the bottom surface 18. The other second lead portion 52b is positioned outward of the other first lead portion 51b. The width (maximum width) W2 of the other second lead portion 52b is wider than the width (maximum width) W1 of the other first lead portion 51b.

[0121] The other first lead portion 51b and the other second lead portion 52b at least partially overlap each other when viewed from a direction perpendicular to the other side surface 11b. In other words, the other first lead portion 51b and the other second lead portion 52b at least partially face each other in a direction perpendicular to the other side surface 11b. In the region where the other first lead portion 51b and the other second lead portion 52b face each other, the facing distance between the conductor plate 20c included in the other first lead portion 51b and the conductor plate 20c included in the other second lead portion 52b is at least twice the thickness of the insulating coating 20i, for example, 20 μm to 50 μm.

[0122] The other second terminal 62b is connected to the end of the other second lead-out portion 52b on the bottom surface 18 side. The other second terminal 62b is formed by being bent relative to the other second lead-out portion 52b. The other second terminal 62b is bent to face the bottom surface 18, and at least a portion of it is housed in the other recess 18b. The other second terminal 62b protrudes outward from the bottom surface 18, for example, protruding 0.1 mm from the bottom surface 18. Note that the other first terminal 61b and the other second terminal 62b do not overlap each other when viewed in a direction perpendicular to the side surface 11b.

[0123] As described above, in the transformer inductor 1A of this embodiment, the first lead portion 51 and the second lead portion 52 at least partially overlap each other when viewed from a direction perpendicular to the side surface 11a. This allows the first lead portion 51 and the second lead portion 52 to be coupled to each other outside the magnetic body 10. This allows the coupling coefficient k of the transformer inductor 1A to be improved.

[0124] Furthermore, in the transformer inductor 1A of this embodiment, the width W1 of the first inner conductor 31 and the width W2 of the second inner conductor 32 are different in length. This configuration shortens the magnetic path length of the magnetic flux circulating around the first inner conductor 31 and the second inner conductor 32. This makes it possible to improve the self-inductance L of the first conductor 21 and the second conductor 22 while maintaining a high value of the coupling coefficient k in the transformer inductor 1A. This reduces the size of the magnetic body 10, thereby enabling the miniaturization of the transformer inductor 1A.

[0125] [Effects, etc.] The effects of the above-described transformer inductor 1A will be described in comparison with a reference example, etc. The reference example is similar to the inductor 901 shown in FIG.

[0126] First, the coupling coefficient, self-inductance, DC resistance, etc. of the transformer inductor 1A when the width of the second conductor 22 is changed will be described.

[0127] Fig. 19 is a table showing the coupling coefficient k when the width of the first conductor 21 is changed, as well as the self-inductance L, DC resistance DCR, etc. of the first conductor 21 and the second conductor 22. Fig. 20 is a graph showing the coupling coefficient k when the width of the first conductor 21 is changed, as well as the self-inductance L, DC resistance DCR, etc. of the first conductor 21 and the second conductor 22. Note that Fig. 20 is a graph of some of the data shown in Fig. 19 .

[0128] 19 shows the coupling coefficient k of the inductor, the DC resistance DCR, self-inductance L, and short-circuit inductance Ls of the first conductor 21, and the DC resistance DCR, self-inductance L, and short-circuit inductance Ls of the second conductor 22. The short-circuit inductance Ls is the value measured when the inductance of one coil is measured with the other coil short-circuited, and is also called leakage inductance.

[0129] The coupling coefficient k shown in FIG. 19 is derived from the following (Equation 1).

[0130] k=(1-Ls / L) １／２... (Equation 1) The coupling coefficient k shown in the figure is a value calculated using the self-inductance L and short-circuit inductance Ls of the first conductor 21. The coupling coefficient k is a value when the thickness of the insulating coating 20i is 15 μm. In this example, a high coupling coefficient k is obtained when the coupling coefficient k is 0.95 or higher. The facing ratio between the first lead portion 51 and the second lead portion 52 in the figure is 80%. The facing ratio will be described later.

[0131] 19 shows data obtained when the width of the second conductor 22 is fixed at 0.55 mm and the width of the first conductor 21 is narrowed in 0.1 mm increments from 0.55 mm to 0.25 mm. The case where the width of the first conductor 21 is 0.55 mm corresponds to the above-mentioned Reference Example, and the cases where the width of the first conductor 21 is 0.45 mm, 0.35 mm, and 0.25 mm correspond to Embodiment 2. The widths of the first conductor 21, 0.45 mm, 0.35 mm, and 0.25 mm, are 0.82 times, 0.64 times, and 0.45 times the width of the second conductor 22, 0.55 mm, respectively.

[0132] 19 and 20 , as the width of the first conductor 21 is changed from 0.55 mm to 0.25 mm, the self-inductance L of the first conductor 21 and the self-inductance L of the second conductor 22 increase. Meanwhile, although the coupling coefficient k decreases slightly, it remains high at 0.95 or higher. Furthermore, although the DC resistance DCR of the first conductor 21 increases, the DC resistance DCR of the second conductor 22 remains the same.

[0133] In this way, by making the width of the first conductor 21 narrower than the width of the second conductor 22, specifically by making the width dimension of the first conductor 21 between 0.45 and 0.82 times the width dimension of the second conductor 22, it is possible to increase the self-inductance L while maintaining a high coupling coefficient k.

[0134] Next, the coupling coefficient, self-inductance, DC resistance, etc. of the transformer-inductor 1A when the height of the transformer-inductor 1A is changed will be described.

[0135] FIG. 21 is a diagram showing an example of an inductor 1A having a different height.

[0136] The height of the transformer inductor 1A varies depending on the height of the magnetic body 10, and therefore, an example in which the height of the transformer inductor 1A is changed by changing the height of the magnetic body 10 will be described below.

[0137] The height of the transformer inductor 1A shown in (a) of Fig. 21 is 1.85 mm, and the height of the transformer inductor 1A shown in (b) of Fig. 21 is 1.69 mm. The height of the transformer inductor 1A shown in (b) of Fig. 21 is 8.6% shorter than that of the transformer inductor 1A shown in (a).

[0138] Fig. 22 is a table showing the coupling coefficient k and the self-inductance L of the first conductor 21 and the second conductor 22 when the height of the inductor 1A is changed. Fig. 23 is a graph showing the self-inductance L of the first conductor 21 and the second conductor 22 when the height of the inductor 1A is changed. Note that Fig. 23 is a graph of some of the data shown in Fig. 22.

[0139] 22 shows an inductor 901 of the reference example. In the inductor 901 of the reference example, the width of the first conductor 21 is 0.55 mm, and the height of the inductor is 1.85 mm.

[0140] The second and subsequent lines in Fig. 22 are an example of embodiment 2. Figs. 22 and 23 show data obtained when the width of the first conductor 21 is 0.35 mm, the width of the second conductor 22 is 0.55 mm, and the height of the transformer inductor 1A is changed from 1.85 mm to 1.61 mm. The height positions of the first inner conductor 31 and the second inner conductor 32 were adjusted so that the height of the magnetic body 10 was changed and the boundary surface between the first inner conductor 31 and the second inner conductor 32 was located at half the height of the magnetic body 10. The facing ratio between the first lead portion 51 and the second lead portion 52 in the figure is 80%.

[0141] As shown in Figures 22 and 23, the self-inductance L of the first conductor 21 and the self-inductance L of the second conductor 22 decrease as the height of the transformer inductor 1A is changed from 1.85 mm to 1.61 mm. However, in this example, even when the height of the transformer inductor 1A is reduced to 1.69 mm, the self-inductance L of the second conductor 22 is 21.34 nH, which is approximately the same as the self-inductance of the inductor 901 of the reference example, 21.00 nH. In other words, by setting the width of the first conductor 21 to 0.35 mm and the width of the second conductor 22 to 0.55 mm, the self-inductance L can be increased. Therefore, even when the height of the transformer inductor 1A is reduced as described above, a self-inductance equivalent to that of the reference example can be achieved. In this example, the height can be changed from (a) to (b) in Figure 21, reducing the height of the transformer inductor 1A by 8.6%. This allows the transformer inductor 1A to be miniaturized.

[0142] Next, the relationship between the coupling coefficient k and the facing ratio of the first lead section 51 and the second lead section 52 will be described.

[0143] FIG. 24 is a diagram showing an example of an inductor in which the facing ratios of the first lead portion 51 and the second lead portion 52 are different.

[0144] Fig. 24 shows the transformer inductor 1A as viewed from a direction perpendicular to the side surface 11b. While the figure shows the case as viewed from the side surface 11b, the case as viewed from the side surface 11a is similar. Fig. 24(a) shows an example where the opposing ratio is 0%, (b) shows an example where the opposing ratio is 40%, and (c) shows an example where the opposing ratio is 80%. The opposing ratio Ro is defined by the following (Equation 2).

[0145] Ro (%) = (Ho / H1) × 100 (Equation 2) H1: length of first lead portion 51 in a direction perpendicular to bottom surface 18 (length from top to bottom end) Ho: length of opposing relationship between first lead portion 51 and second lead portion 52 in a direction perpendicular to bottom surface 18 FIG. 25 is a table showing the coupling coefficient k, the self-inductance L, and the DC resistance DCR of first conductor 21 and second conductor 22 when the opposing ratio Ro of first lead portion 51 and second lead portion 52 is changed. FIG. 26 is a graph showing the coupling coefficient k and the DC resistance DCR of first conductor 21 and second conductor 22 when the opposing ratio Ro of first lead portion 51 and second lead portion 52 is changed. Note that FIG. 25 is a graph of some of the data shown in FIG. 26 .

[0146] 25 shows data obtained when the width of the first conductor 21 is 0.35 mm and the width of the second conductor 22 is 0.55 mm and the opposing ratio is changed from 0% to 80%, respectively. The height of the transformer inductor 1A is 1.85 mm.

[0147] 25 and 26, in the transformer inductor 1A, the coupling coefficient k increases as the opposing ratio Ro increases. Specifically, when the opposing ratio Ro is 10%, the coupling coefficient k is 0.9528, and when the opposing ratio Ro is 80%, the coupling coefficient k is 0.9653, both of which are higher than 0.95.

[0148] In this way, by setting the facing ratio Ro to be 10% or more and 80% or less, the coupling coefficient k can be increased. Also, by setting the facing ratio Ro to be 10% or more and 80% or less, the direct current resistance DCR can be reduced.

[0149] Furthermore, by setting the facing ratio Ro to be 40% or more and 80% or less, the coupling coefficient k can be further increased. Furthermore, by setting the facing ratio Ro to be 40% or more, the short-circuit inductance Ls, which is leakage inductance, can be set to approximately 2 nH or less. The reason why the facing ratio Ro is set to be 80% or less is to avoid electrical contact with the opposing conductor when the transformer inductor 1A is mounted on a circuit board.

[0150] (Summary) Inductors 1 and 1A according to one aspect of the present disclosure will be illustrated.

[0151] The inductor of Example 1 includes a magnetic body 10, a first conductor 21, and a second conductor 22. The magnetic body 10 has a bottom surface 18, a top surface 19 facing away from the bottom surface 18, and a side surface connecting the bottom surface 18 and the top surface 19. The first conductor 21 has a first internal conductor 31 provided inside the magnetic body 10 and a first external conductor 41 provided outside the magnetic body 10. The second conductor 22 has a second internal conductor 32 provided inside the magnetic body 10 and a second external conductor 42 provided outside the magnetic body 10. The first internal conductor 31 and the second internal conductor 32 at least partially overlap each other when viewed from a direction perpendicular to the bottom surface 18. The first external conductor 41 has a first lead portion 51 connected to the first internal conductor 31 at a side surface and extending toward the bottom surface 18. The second outer conductor 42 has a second lead portion 52 connected to the second inner conductor 32 at its side surface and extending toward the bottom surface 18. The width W1 of the first inner conductor 31 perpendicular to the extension direction of the first inner conductor 31 and the width W2 of the second inner conductor 32 perpendicular to the extension direction of the second inner conductor 32 are different from each other.

[0152] According to this configuration, the first conductor 21 and the second conductor 22 can be coupled inside and outside the magnetic body 10. This improves the coupling coefficient k of the inductor. Furthermore, by making the width W1 of the first inner conductor 31 and the width W2 of the second inner conductor 32 different, the magnetic path length of the magnetic flux circulating around the first inner conductor 31 and the second inner conductor 32 can be shortened, and the self-inductance L of the first conductor 21 and the second conductor 22 can be improved. This reduces the size of the magnetic body 10 and makes it possible to miniaturize the inductor while maintaining a high coupling coefficient k of the inductor.

[0153] The inductor 1 of Example 2 is the inductor described in Example 1, in which the second internal conductor 32 is positioned closer to the top surface 19 than the first internal conductor 31, and the width W2 of the second internal conductor 32 may be narrower than the width W1 of the first internal conductor 31.

[0154] In this way, by making the width W2 of the second inner conductor 32 narrower than the width W1 of the first inner conductor 31, it is possible to shorten the magnetic path length of the magnetic flux circulating around the first inner conductor 31 and the second inner conductor 32, and improve the self-inductance L of the first conductor 21 and the second conductor 22. This makes it possible to reduce the size of the magnetic body 10 and miniaturize the inductor 1 while maintaining a high coupling coefficient k in the inductor 1.

[0155] The inductor 1 of Example 3 is the inductor described in Example 2, and the dimension of the width W2 of the second inner conductor 32 may be 0.45 to 0.82 times the dimension of the width W1 of the first inner conductor 31.

[0156] In this way, by setting the width W2 of the second inner conductor 32 to be 0.45 to 0.82 times the width W1 of the first inner conductor 31, it is possible to shorten the magnetic path length of the magnetic flux circulating around the first inner conductor 31 and the second inner conductor 32 and improve the self-inductance L of the first conductor 21 and the second conductor 22. This allows the size of the magnetic body 10 to be reduced while maintaining a high coupling coefficient k in the inductor 1, thereby making the inductor 1 more compact.

[0157] The inductor 1A of Example 4 is the inductor described in Example 1, in which the first inner conductor 31 is positioned closer to the bottom surface 18 than the second inner conductor 32, and the width W1 of the first inner conductor 31 may be narrower than the width W2 of the second inner conductor 32.

[0158] In this way, by making the width W1 of the first inner conductor 31 narrower than the width W2 of the second inner conductor 32, it is possible to shorten the magnetic path length of the magnetic flux circulating around the first inner conductor 31 and the second inner conductor 32, and improve the self-inductance L of the first conductor 21 and the second conductor 22. This makes it possible to reduce the size of the magnetic body 10 and miniaturize the inductor 1A while maintaining a high value of the coupling coefficient k in the inductor 1A.

[0159] The inductor 1A of Example 5 is the inductor described in Example 4, and the width W1 of the first inner conductor 31 may be 0.45 to 0.82 times the width W2 of the second inner conductor 32.

[0160] In this way, by setting the width W1 of the first inner conductor 31 to be 0.45 to 0.82 times the width W2 of the second inner conductor 32, it is possible to shorten the magnetic path length of the magnetic flux circulating around the first inner conductor 31 and the second inner conductor 32 and improve the self-inductance L of the first conductor 21 and the second conductor 22. This makes it possible to reduce the size of the magnetic body 10 and miniaturize the inductor 1A while maintaining a high coupling coefficient k in the inductor 1A.

[0161] The inductor of Example 6 is the inductor according to any one of Examples 1 to 5, wherein the first inner conductor 31 and the second inner conductor 32 may be parallel to the bottom surface 18 and extend in the same direction.

[0162] According to this configuration, the first conductor 21 and the second conductor 22 can be coupled inside and outside the magnetic body 10. This can improve the coupling coefficient k of the inductor.

[0163] The inductor of Example 7 is the inductor according to any one of Examples 1 to 6, wherein the side surfaces include one side surface 11a and the other side surface 11b facing each other. The first inner conductor 31 and the second inner conductor 32 each extend perpendicular to the one side surface 11a. The first inner conductor 31 has one end 31a connected to the one side surface 11a and the other end 31b connected to the other side surface 11b. The second inner conductor 32 has one end 32a connected to the one side surface 11a and the other end 32b connected to the other side surface 11b. The first lead portion 51 has one first lead portion 51a connected to the one end 31a of the first inner conductor 31 and the other first lead portion 51b connected to the other end 31b of the first inner conductor 31. The second lead portion 52 has one second lead portion 52a connected to one end 32a of the second inner conductor 32, and the other second lead portion 52b connected to the other end 32b of the second inner conductor 32. The one first lead portion 51a and the one second lead portion 52a may at least partially overlap each other when viewed from a direction perpendicular to one side surface 11a, and the other first lead portion 51b and the other second lead portion 52b may at least partially overlap each other when viewed from a direction perpendicular to the other side surface 11b.

[0164] According to this configuration, one of the first lead portions 51a and one of the second lead portions 52a can be coupled to each other outside the magnetic body 10. Also, the other of the first lead portions 51b and the other of the second lead portions 52b can be coupled to each other outside the magnetic body 10. This can improve the coupling coefficient k of the inductor.

[0165] The inductor of Example 8 is the inductor described in Example 7, in which one first lead portion 51a is arranged closer to one side surface 11a than one second lead portion 52a, and the other first lead portion 51b is arranged closer to the other side surface 11b than the other second lead portion 52b. The width W2 of one second lead portion 52a may be narrower than the width W1 of one first lead portion 51a, and the width W2 of the other second lead portion 52b may be narrower than the width W1 of the other first lead portion 51b.

[0166] In this way, by making the width W2 of one second lead portion 52a narrower than the width W1 of one first lead portion 51a, the magnetic path length of the magnetic flux circulating around the one second lead portion 52a and the one first lead portion 51a can be shortened, thereby improving the self-inductance L of the first conductor 21 and the second conductor 22. Furthermore, by making the width W2 of the other second lead portion 52b narrower than the width W1 of the other first lead portion 51b, the magnetic path length of the magnetic flux circulating around the other second lead portion 52b and the other first lead portion 51b can be shortened, thereby improving the self-inductance L of the first conductor 21 and the second conductor 22. This makes it possible to reduce the size of the magnetic body 10 and miniaturize the inductor while maintaining a high coupling coefficient k in the inductor.

[0167] The inductor of Example 9 is the inductor described in Example 8, wherein the dimension of the width W2 of one second draw-out portion 52a is 0.45 to 0.82 times the dimension of the width W1 of one first draw-out portion 51a, and the dimension of the width W2 of the other second draw-out portion 52b is 0.45 to 0.82 times the dimension of the width W1 of the other first draw-out portion 51b.

[0168] The above configuration shortens the magnetic path length of the magnetic flux circulating around the second lead portion 52 and the first lead portion 51, thereby improving the self-inductance L of the first conductor 21 and the second conductor 22. This allows the size of the magnetic body 10 to be reduced, thereby miniaturizing the inductor, while maintaining a high coupling coefficient k in the inductor.

[0169] The inductor of Example 10 is the inductor described in Example 8 or 9, in which the first drawer portion 51 and the second drawer portion 52 each extend along a direction perpendicular to the bottom surface 18, and the length of the first drawer portion 51 in the direction perpendicular to the bottom surface 18 is H1, the length of the opposition between the first drawer portion 51 and the second drawer portion 52 in the direction perpendicular to the bottom surface 18 is Ho, and the opposition ratio between the first drawer portion 51 and the second drawer portion 52 is Ro, and the opposition ratio is defined as calculated by Ro (%) = (Ho / H1) × 100, then Ro may be 10% or more and 80% or less.

[0170] As described above, by setting the facing ratio between the first lead portion 51 and the second lead portion 52, the coupling coefficient k of the inductor can be improved.

[0171] The inductor described in Example 11 is the inductor described in Example 7, in which one first lead portion 51a is arranged closer to one side surface 11a than one second lead portion 52a, and the other first lead portion 51b is arranged closer to the other side surface 11b than the other second lead portion 52b. The width W1 of one first lead portion 51a may be narrower than the width W2 of one second lead portion 52a, and the width W1 of the other first lead portion 51b may be narrower than the width W2 of the other second lead portion 52b.

[0172] In this way, by making the width W1 of one first lead portion 51a narrower than the width W2 of one second lead portion 52a, the magnetic path length of the magnetic flux circulating around one second lead portion 52a and one second lead portion 52a can be shortened, thereby improving the self-inductance L of the first conductor 21 and the second conductor 22. Furthermore, by making the width W1 of the other first lead portion 51b narrower than the width W2 of the other second lead portion 52b, the magnetic path length of the magnetic flux circulating around the other first lead portion 51b and the other second lead portion 52b can be shortened, thereby improving the self-inductance L of the first conductor 21 and the second conductor 22. This makes it possible to reduce the size of the magnetic body 10 and miniaturize the inductor while maintaining a high coupling coefficient k in the inductor.

[0173] The inductor of Example 12 is the inductor described in Example 11, wherein the width W1 of one first draw-out portion 51a is 0.45 to 0.82 times the width W2 of one second draw-out portion 52a, and the width W1 of the other first draw-out portion 51b is 0.45 to 0.82 times the width W2 of the other second draw-out portion 52b.

[0174] The above configuration shortens the magnetic path length of the magnetic flux circulating around the second lead portion 52 and the first lead portion 51, thereby improving the self-inductance L of the first conductor 21 and the second conductor 22. This allows the size of the magnetic body 10 to be reduced, thereby miniaturizing the inductor, while maintaining a high coupling coefficient k in the inductor.

[0175] The inductor of Example 13 is the inductor described in Example 11 or 12, wherein the first drawer portion 51 and the second drawer portion 52 each extend along a direction perpendicular to the bottom surface 18, and the length of the first drawer portion 51 in the direction perpendicular to the bottom surface 18 is defined as H1, the length of the opposition between the first drawer portion 51 and the second drawer portion 52 in the direction perpendicular to the bottom surface 18 is defined as Ho, the opposition ratio between the first drawer portion 51 and the second drawer portion 52 is defined as Ro, and the opposition ratio is calculated as Ro (%) = (Ho / H1) × 100, then Ro may be 10% or more and 80% or less.

[0176] As described above, by setting the facing ratio between the first lead portion 51 and the second lead portion 52, the coupling coefficient k of the inductor can be improved.

[0177] (Other Embodiments, etc.) While the inductors and the like according to the embodiments and modifications of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and modifications. As long as they do not deviate from the gist of the present disclosure, various modifications that a person skilled in the art could conceive of to the embodiments and modifications, as well as other forms constructed by combining some of the components of the embodiments and modifications, are also included in the scope of the present disclosure.

[0178] For example, the present disclosure also includes electrical appliances or electrical circuits using the above-described inductor. Examples of electrical appliances include power supply devices equipped with the above-described inductor and various devices equipped with such power supply devices.

[0179] For example, when multiple transformer inductors are used in a multi-phase power supply system, an electrical circuit having multiple transformer inductors may be configured such that either the first conductor 21 or the second conductor 22 of each transformer inductor is arranged between the power supply and the load, and either the other first conductor 21 or the second conductor 22 of each transformer inductor is connected in series.

[0180] The inductor according to the present invention can provide an inductor with a high coupling coefficient and a small size, and is therefore industrially useful.

[0181] REFERENCE SIGNS LIST 1, 1A Inductor (transinductor) 10 Magnetic body 11a, 11b, 11c, 11d Side surface 18 Bottom surface 18a, 18b Recess 19 Top surface 20c Conductor plate 20i Insulating coating 21 First conductor 22 Second conductor 31 First internal conductor 31a One end 31b Other end 32 Second internal conductor 32a One end 32b Other end 41 First outer conductor 42 Second outer conductor 51 First lead portion 51a One first lead portion 51b Other first lead portion 52 Second lead portion 52a One second lead portion 52b Other second lead portion 61 First terminal portion 61a One first terminal portion 61b Other first terminal portion 62 Second terminal portion 62a One second terminal portion 62b Other second terminal portion d1, d2 Distance do: opposing distance H1: length of first lead-out portion Ho: opposing length Ro: opposing ratio W1: width of first inner conductor, width of first lead-out portion W2: width of second inner conductor, width of second lead-out portion

Claims

1. A magnetic body, a first conductor, and a second conductor, wherein the magnetic body has a bottom surface, a top surface facing away from the bottom surface, and a side surface connecting the bottom surface and the top surface, the first conductor has a first internal conductor provided inside the magnetic body and a first external conductor provided outside the magnetic body, the second conductor has a second internal conductor provided inside the magnetic body and a second external conductor provided outside the magnetic body, the first internal conductor and the second internal conductor at least partially overlap each other when viewed from a direction perpendicular to the bottom surface, the first external conductor has a first lead portion connected to the first internal conductor at the side surface and extending toward the bottom surface, and the second external conductor has a second lead portion connected to the second internal conductor at the side surface and extending toward the bottom surface, An inductor, wherein the width of the first inner conductor perpendicular to the direction in which the first inner conductor extends and the width of the second inner conductor perpendicular to the direction in which the second inner conductor extends are different from each other.

2. The inductor according to claim 1, wherein the second internal conductor is disposed closer to the top surface than the first internal conductor, and the width of the second internal conductor is narrower than the width of the first internal conductor.

3. The inductor according to claim 2, wherein the width of the second internal conductor is 0.45 to 0.82 times the width of the first internal conductor.

4. The inductor according to claim 1, wherein the first internal conductor is disposed closer to the bottom surface than the second internal conductor, and the width of the first internal conductor is narrower than the width of the second internal conductor.

5. The inductor according to claim 4, wherein the width of the first inner conductor is 0.45 to 0.82 times the width of the second inner conductor.

6. An inductor according to any one of claims 1 to 5, wherein the first internal conductor and the second internal conductor are parallel to the bottom surface and extend in the same direction.

7. The side surfaces have one side surface and the other side surface facing back to back, the first internal conductor and the second internal conductor each extend along a direction perpendicular to the one side surface, the first internal conductor has one end connected to the one side surface and the other end connected to the other side surface, the second internal conductor has one end connected to the one side surface and the other end connected to the other side surface, the first lead-out portion has one first lead-out portion connected to one end of the first internal conductor and the other first lead-out portion connected to the other end of the first internal conductor, the second lead-out portion has one second lead-out portion connected to one end of the second internal conductor and the other second lead-out portion connected to the other end of the second internal conductor, the one first lead-out portion and the one second lead-out portion at least partially overlap each other when viewed from a direction perpendicular to the one side surface, and the other first lead-out portion and the other second lead-out portion at least partially overlap each other when viewed from a direction perpendicular to the other side surface.

10. The inductor of claim 1.

8. An inductor as described in claim 7, wherein the one first lead-out portion is arranged closer to the one side surface than the one second lead-out portion, the other first lead-out portion is arranged closer to the other side surface than the other second lead-out portion, the width of the one second lead-out portion is narrower than the width of the one first lead-out portion, and the width of the other second lead-out portion is narrower than the width of the other first lead-out portion.

9. The inductor according to claim 8, wherein the width of the one second lead portion is 0.45 to 0.82 times the width of the one first lead portion, and the width of the other second lead portion is 0.45 to 0.82 times the width of the other first lead portion.

10. The inductor according to claim 8 or 9, wherein the first lead-out portion and the second lead-out portion extend in a direction perpendicular to the bottom surface, H1 is the length of the first lead-out portion in the direction perpendicular to the bottom surface, Ho is the length over which the first lead-out portion and the second lead-out portion face each other in the direction perpendicular to the bottom surface, Ro is the facing ratio between the first lead-out portion and the second lead-out portion, and when the facing ratio is calculated by Ro (%) = (Ho / H1) × 100, Ro is 10% or more and 80% or less.

11. An inductor as described in claim 7, wherein the one first lead-out portion is positioned closer to the one side surface than the one second lead-out portion, the other first lead-out portion is positioned closer to the other side surface than the other second lead-out portion, the width of the one first lead-out portion is narrower than the width of the one second lead-out portion, and the width of the other first lead-out portion is narrower than the width of the other second lead-out portion.

12. The inductor according to claim 11, wherein the width of one of the first lead portions is 0.45 to 0.82 times the width of one of the second lead portions, and the width of the other of the first lead portions is 0.45 to 0.82 times the width of the other of the second lead portions.

13. The inductor according to claim 11 or 12, wherein the first lead-out portion and the second lead-out portion each extend in a direction perpendicular to the bottom surface, H1 is the length of the first lead-out portion in the direction perpendicular to the bottom surface, Ho is the length over which the first lead-out portion and the second lead-out portion face each other in the direction perpendicular to the bottom surface, Ro is the facing ratio between the first lead-out portion and the second lead-out portion, and when the facing ratio is calculated by Ro (%) = (Ho / H1) × 100, Ro is 10% or more and 80% or less.

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