Inductor

Abstract

This inductor comprises a magnetic body, a first conductor, and a second conductor. The magnetic body has a bottom surface, a top surface, and side surfaces. 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 outer conductor has a first lead-out portion that is connected to the first inner conductor on a side surface of the magnetic body and extends toward the bottom surface side, and the second outer conductor has a second lead-out portion that is connected to the second inner conductor on a side surface of the magnetic body and extends toward the bottom surface side. At least a portion of the first lead-out portion and the second lead-out portion overlap each other when viewed from a direction perpendicular to the side surfaces of the magnetic body.

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 improving the coupling coefficient.

[0006] In order to solve the above-mentioned problems, the present disclosure provides a magnetic body and a pair of conductors, 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 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, 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, and the first lead portion and the second lead portion at least partially overlap each other when viewed from a direction perpendicular to the side surface.

[0007] According to the present disclosure, the coupling coefficient in an inductor can be improved.

[0008] FIG. 1 is a perspective view of an inductor according to a first embodiment. FIG. 2 is a perspective view showing a pair of conductors 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 a coupling coefficient and the like of the inductor according to the first embodiment and the inductor according to the first comparative example. FIG. 6 is a diagram explaining the facing ratio of a first lead portion and a second lead portion of an inductor. FIG. 7 is a diagram showing a relationship between a coupling coefficient in an inductor and a thickness of an insulating coating on a conductor. FIG. 8 is a diagram showing a relationship between a coupling coefficient in an inductor and an increment in distance between a first internal conductor and a bottom surface. FIG. 9 is a flowchart showing a manufacturing method of the inductor according to the first embodiment. FIG. 10 is a perspective view of an inductor according to a second embodiment. FIG. 11 is a perspective view showing a pair of conductors included in the inductor according to the second embodiment. FIG. 12 is a diagram showing a coupling coefficient and the like of the inductor according to the second embodiment and the inductor according to the second comparative example. FIG. 13 is a perspective view of an inductor according to a third embodiment. FIG. 14 is a perspective view showing a pair of conductors included in the inductor according to the third embodiment. FIG. 15 is a diagram showing a coupling coefficient and the like of the inductor according to the third embodiment and the inductor according to the third comparative example. Fig. 16 is a perspective view of an inductor according to embodiment 4. Fig. 17 is a perspective view showing a pair of conductors included in the inductor according to embodiment 4.

[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 pair of conductors 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 the insulating coating 20i is not shown in Fig. 2. 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 section 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. 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] The first internal conductor 31 is a portion embedded in the magnetic body 10. The first internal conductor 31 is disposed closer to the bottom surface 18 than a second internal conductor 32, which will be described later. That is, the first internal conductor 31 is disposed closer to the bottom surface 18 than the second internal conductor 32. The first internal conductor 31 extends linearly in a direction perpendicular to the side surface 11 a (or side surface 11 b) of the magnetic body 10, and is disposed parallel to the bottom surface 18 (or top surface 19). The first internal conductor 31 has one end 31 a connected to one side surface 11 a and the other end 31 b connected to the other side surface 11 b (see FIG. 3 ).

[0029] The first outer conductor 41 has a plurality of first lead portions 51 and a plurality of first terminal portions 61 .

[0030] 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.

[0031] 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.

[0032] One 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. One 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. One first lead portion 51a is arranged closer to one side surface 11a than one second lead portion 52a, which will be described later. In other words, one first lead portion 51a is arranged closer to one side surface 11a than one second lead portion 52a.

[0033] Furthermore, one of the first lead portions 51a has a wide portion w1a connected to one end 31a of the first internal conductor 31 and a narrow portion n1a connected to the wide portion w1a. The width of the wide portion w1a is the same as the width of the first internal conductor 31. The width of the narrow portion n1a is narrower than the wide portion w1a and is the same as the width of one of the first terminal portions 61a. 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).

[0034] One first lead portion 51a has an end connected to one end 31a of the first internal conductor 31 and an end on the bottom surface 18 side opposite the end connected to the first end. One first terminal portion 61a is connected to the end of one first lead portion 51a on the bottom surface 18 side. One first terminal portion 61a is formed by being bent relative to one first lead portion 51a. One first terminal portion 61a is bent to face the bottom surface 18, and at least a portion of it is housed in one recess 18a. One first terminal portion 61a protrudes outward from the bottom surface 18 (in a direction away from the bottom surface 18), for example, by 0.1 mm from the bottom surface 18.

[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 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 located closer to the other side surface 11b than the other second lead portion 52b, which will be described later. In other words, the other first lead portion 51b is located closer to the other side surface 11b than the other second lead portion 52b.

[0036] The other first lead portion 51b has a wide portion w1b connected to the other end 31b of the first inner conductor 31, and a narrow portion n1b connected to the wide portion w1b. The width of the wide portion w1b is the same as the width of the first inner conductor 31. The width of the narrow portion n1b is narrower than the wide portion w1b and is the same as the width of the other first terminal portion 61b.

[0037] The other first lead portion 51b has an end portion connected to the other end 31b of the first internal conductor 31 and an end portion on the bottom surface 18 side opposite the end portion. The other first terminal portion 61b is connected to the end portion on the bottom surface 18 side of the other first lead portion 51b. The other first terminal portion 61b is formed by being bent relative to the other first lead portion 51b. The other first terminal portion 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 portion 61b protrudes outward from the bottom surface 18, for example, by 0.1 mm.

[0038] 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.

[0039] 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.

[0040] The second internal conductor 32 is a portion embedded in the magnetic body 10. The second internal conductor 32 is disposed closer to the top surface 19 than the first internal conductor 31. The second internal conductor 32 extends linearly along a direction perpendicular to the side surface 11 a (or side surface 11 b) of the magnetic body 10, and is disposed parallel to the bottom surface 18 (or top surface 19). The second internal conductor 32 has one end 32 a connected to one side surface 11 a and the other end 32 b connected to the other side surface 11 b (see FIG. 3 ).

[0041] The width of the second internal conductor 32 is the same as the width of the first internal conductor 31. The first internal conductor 31 and the second internal conductor 32 at least partially overlap when viewed from a direction perpendicular to the bottom surface 18 (or the top surface 19). Specifically, the conductor plate 20c included in the first internal conductor 31 and the conductor plate 20c included in the second internal conductor 32 at least partially face each other in the direction perpendicular to the bottom surface 18. The opposing distance d0 (see FIGS. 3 and 4 ) between the conductor plate 20c included in the first internal conductor 31 and the conductor plate 20c included in the second internal conductor 32 is at least twice the thickness of the insulating coating 20i, and is, for example, 20 μm to 50 μm.

[0042] The distance d2 between the second internal conductor 32 and the top surface 19 may be the same as the distance d1 between the first internal conductor 31 and the bottom surface 18, but is not limited to this, and the distance d2 may be shorter than the distance d1. In other words, the distance d1 between the first internal conductor 31 and the bottom surface 18 may be longer than the distance d2 between the second internal conductor 32 and the top surface 19. In other words, the thickness of the magnetic body 10 provided between the first internal conductor 31 and the bottom surface 18 may be thicker than the thickness of the magnetic body 10 provided between the second internal conductor 32 and the top surface 19.

[0043] The second outer conductor 42 has a plurality of second lead portions 52 and a plurality of second terminal portions 62 .

[0044] 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.

[0045] 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.

[0046] 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 the one side surface 11a and is then bent toward the bottom surface 18, and extends toward the bottom surface 18 in a direction perpendicular to the bottom surface 18, i.e., along the one side surface 11a. The second second lead portion 52a is disposed outward of the first first lead portion 51a.

[0047] The second lead portion 52a has a wide portion w2a connected to one end 32a of the second inner conductor 32 and a narrow portion n2a connected to the wide portion w2a. The width of the wide portion w2a is the same as the width of the second inner conductor 32. The width of the narrow portion n2a is narrower than the wide portion w2a and is the same as the width of the second terminal portion 62a. The wide portion w1a of the first lead portion 51a and the wide portion w2a of the second lead portion 52a are the same length, and the wide portion w1a of the first lead portion 51a and the wide portion w2a of the second lead portion 52a overlap each other when viewed from a direction perpendicular to one side surface 11a.

[0048] That is, 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, and is, for example, 20 μm to 50 μm.

[0049] The first second lead portion 52a has an end connected to one end 32a of the second internal conductor 32 and an end opposite the end connected to the bottom surface 18. The second terminal portion 62a is connected to the end of the second lead portion 52a facing the bottom surface 18. The second terminal portion 62a is formed by being bent relative to the second lead portion 52a. The second terminal portion 62a is bent to face the bottom surface 18, and at least a portion of the second terminal portion 62a is housed in one of the recesses 18a. The second terminal portion 62a protrudes outward from the bottom surface 18, for example, by 0.1 mm. The first terminal portion 61a and the second terminal portion 62a do not overlap each other when viewed 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, 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 second lead portion 52b is disposed outward of the other first lead portion 51b.

[0051] The other second lead portion 52b has a wide portion w2b connected to the other end 32b of the second inner conductor 32 and a narrow portion n2b connected to the wide portion w2b. The width of the wide portion w2b is the same as the width of the second inner conductor 32. The width of the narrow portion n2b is narrower than the wide portion w2b and is the same as the width of the other second terminal portion 62b. The wide portion w1b of the other first lead portion 51b and the wide portion w2b of the other second lead portion 52b have the same length, and the wide portion w1b of the other first lead portion 51b and the wide portion w2b of the other second lead portion 52b overlap each other when viewed from a direction perpendicular to the other side surface 11b.

[0052] That is, 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.

[0053] The other second lead portion 52b has an end connected to the other end 32b of the second internal conductor 32 and an end opposite the end connected to the other end 32b of the second internal conductor 32, facing the bottom surface 18. The other second terminal portion 62b is connected to the end of the other second lead portion 52b facing the bottom surface 18. The other second terminal portion 62b is formed by being bent relative to the other second lead portion 52b. The other second terminal portion 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 portion 62b protrudes outward from the bottom surface 18, for example, by 0.1 mm from the bottom surface 18. The other first terminal portion 61b and the other second terminal portion 62b do not overlap each other when viewed perpendicular to the side surface 11b.

[0054] 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 between the first conductor 21 and the second conductor 22 in the transformer inductor 1 to be improved.

[0055] Although the above example shows that the width of the wide portion of the first lead portion 51 and the width of the wide portion of the second lead portion 52 are the same when viewed from a direction perpendicular to one side surface 11a, this is not limiting. For example, the width of the wide portion of the first lead portion 51 and the width of the wide portion of the second lead portion 52 may be different. In this case, it is preferable to position these wide portions so that the entire width of the narrower wide portion is included in the entire width of the wider wide portion. In this way, even if the positions of the wide portions are shifted, the wide portions will always face each other within the area of ​​the narrower wide portion, thereby reducing variations in the coupling coefficient due to positional shifts.

[0056] [Effects, etc.] The coupling coefficient, etc. of the transformer-inductor 1 will be described with reference to FIGS.

[0057] Fig. 5 is a diagram showing the coupling coefficients and the like of the inductor 1 of the embodiment 1 and the inductor of the comparative example 1. Note that Fig. 5(b) is a graph of the table shown in Fig. 5(a).

[0058] 5A also shows the self-inductance L, short-circuit inductance Ls, and DC resistance DCR of the first conductor 21, as well as the self-inductance L, short-circuit inductance Ls, and DC resistance DCR of the second conductor 22. The short-circuit inductance Ls is the value obtained by measuring the inductance of one coil when the other coil is short-circuited, and is also called leakage inductance.

[0059] The coupling coefficient k shown in FIG. 5 is derived from the following (Equation 1).

[0060] 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.

[0061] 5 shows the coupling coefficient k when the opposing ratio between the first lead portion 51 and the second lead portion 52 is changed. Note that the coupling coefficient k shown in FIG. 5 is a value when the thickness of the insulating coating 20i is 15 μm.

[0062] Here, 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.

[0063] Fig. 6 is a diagram illustrating the facing ratio Ro of the first lead portion 51 and the second lead portion 52. Fig. 6(a) shows a cross section of the inductor 1 viewed from the same direction as Fig. 3. Note that hatching of the cross section is omitted in Fig. 6. Fig. 6(b) shows a perspective view of the inductor 1. Fig. 6(b) illustrates an example where the facing ratio of the first lead portion 51 and the second lead portion 52 is 50%.

[0064] The facing ratio Ro is defined by the following (Equation 2).

[0065] 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 first lead portion 51 and second lead portion 52 in a direction perpendicular to bottom surface 18 As shown in Figure 5, in the transformer inductor 1 of embodiment 1, the coupling coefficient k increases as the opposing ratio Ro increases. Also, the DC resistance decreases as the opposing ratio Ro increases.

[0066] Here, in order to explain the effect of the transformer-inductor 1 of the first embodiment, a transformer-inductor of a first comparative example will be explained.

[0067] In the transformer inductor of Comparative Example 1, the opposing ratio Ro of the first lead portion 51 and the second lead portion 52 is 0%. In Comparative Example 1, the first conductor 21 has L = 21.70 nH, Ls = 2.26 nH, and DCR = 2.13 mΩ, and the second conductor 22 has L = 21.42 nH, Ls = 2.23 nH, and DCR = 2.81 mΩ. The coupling coefficient k of the transformer inductor of Comparative Example 1 is k = 0.947 according to (Equation 1).

[0068] In contrast, the transformer inductor 1 of embodiment 1 has a coupling coefficient k=0.949 when the opposing ratio Ro is 10%, and a coupling coefficient k=0.969 when the opposing ratio Ro is 80%, both of which are higher than the coupling coefficient k in comparative example 1.

[0069] In this way, by setting the facing ratio Ro of the transformer inductor 1 to be 10% or more and 80% or less, it is possible to make the coupling coefficient k higher than that of the transformer inductor of Comparative Example 1. The facing ratio Ro is set to be 80% or less in order to avoid electrical contact with the opposing conductor when the transformer inductor 1 is mounted on a circuit board.

[0070] Furthermore, in the transformer inductor 1, the coupling coefficient k can be further increased by setting the opposing ratio Ro to be 20% or more and 80% or less. For example, by setting the opposing ratio Ro to be 20% or more, the short-circuit inductance Ls, which is leakage inductance, can be set to approximately 2 nH or less.

[0071] Next, the relationship between the coupling coefficient k and the thickness of the insulating coating 20i will be described with reference to FIG.

[0072] Fig. 7 is a diagram showing the relationship between the coupling coefficient k and the thickness of the insulating coating 20i of the conductor in the inductor 1. Fig. 7(b) is a graph of the table shown in Fig. 7(a).

[0073] 7 also shows the self-inductance L and short-circuit inductance Ls of the first conductor 21, and the self-inductance L and short-circuit inductance Ls of the second conductor 22. The coupling coefficient k shown in FIG. 7 is a value when the facing ratio Ro is 80%.

[0074] 7, in the transformer inductor 1 of embodiment 1, the coupling coefficient k decreases as the thickness of the insulating coating 20i increases. As shown in the figure, for example, if a coupling coefficient k of 0.94 or greater is required, the thickness of the insulating coating 20i is preferably 10 μm or greater and 50 μm or less to ensure a coupling coefficient k of 0.95 or greater. Furthermore, the thickness of the insulating coating 20i may be 15 μm or greater to ensure the insulation of the conductor.

[0075] Next, the relationship between the coupling coefficient k and the distance d1 between the first inner conductor 31 and the bottom surface 18 will be described with reference to FIG.

[0076] Fig. 8 is a diagram showing the relationship between the coupling coefficient k in the inductor 1 and the increment of the distance d1 between the first inner conductor 31 and the bottom surface 18. Fig. 8(b) is a graph of the table shown in Fig. 8(a). The increment is the amount of increase in the distance d1 when the distance d1 = d2 is used as a reference. The distance d2 is assumed to decrease by the same amount as the increase in the distance d1.

[0077] 8 also shows the self-inductance L, short-circuit inductance Ls, and DC resistance DCR of the first conductor 21, and the self-inductance L, short-circuit inductance Ls, and DC resistance DCR of the second conductor 22. The coupling coefficient k shown in FIG. 8 is a value when the facing ratio Ro is 80% and the thickness of the insulating coating 20i is 15 μm.

[0078] 8 , in the transformer inductor 1 of embodiment 1, the self-inductance L can be increased by increasing the distance d1 between the first internal conductor 31 and the bottom surface 18 by 0.25 mm and decreasing the distance d2 between the second internal conductor 32 and the top surface 19 by 0.25 mm. In other words, the self-inductance L can be increased by increasing the thickness of the magnetic body 10 between the first internal conductor 31 and the bottom surface 18 by 0.25 mm and decreasing the thickness of the magnetic body 10 between the second internal conductor 32 and the top surface 19 by 0.25 mm.

[0079] Increasing the distance d1 in this way increases the effective cross-sectional area of ​​the magnetic path of the first coil formed by the first inner conductor 31, the one first lead portion 51a, and the other first lead portion 51b, and the second coil formed by the second inner conductor 32, the one second lead portion 52a, and the other second lead portion 52b. This increases the self-inductance L of each of the first conductor 21 and the second conductor 22. Note that if the distance d1 is made too large, the distance d2 becomes small, reducing the self-inductance L. Therefore, it is desirable that the increment in distance d1, (d1-d2), be 0 < (d1-d2) ≤ 0.4 mm.

[0080] [Method of Manufacturing Inductor] A method of manufacturing the inductor 1 according to the first embodiment will be described.

[0081] FIG. 9 is a flowchart showing a method for manufacturing the inductor 1 according to the first embodiment.

[0082] As shown in FIG. 9, the method for manufacturing the inductor 1 includes a conductor forming step S110, a magnetic body forming step S130, and a bending step S150.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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. 9 , the transformer inductor 1 is produced.

[0087] 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).

[0088] Second Embodiment [Configuration of Inductor] The configuration of an inductor 1A according to a second embodiment will be described with reference to Fig. 10 and Fig. 11. In the second embodiment, an example will be described in which the inductor 1A does not include a first terminal portion 61 and a second terminal portion 62.

[0089] Fig. 10 is a perspective view of an inductor 1A according to embodiment 2. Fig. 11 is a perspective view showing a pair of conductors included in the inductor 1A. Note that in Fig. 11, the insulating coating 20i is not shown.

[0090] The inductor 1A shown in Figures 10 and 11 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 21A and a second conductor 22A. The first conductor 21A and the second conductor 22A are insulated from each other and face each other inside the magnetic body 10. In the inductor 1A of this embodiment, the first conductor 21A and the second conductor 22A face each other outside the magnetic body 10, which makes it possible to improve the coupling coefficient between the first conductor 21A and the second conductor 22A.

[0091] Hereinafter, the inductor 1A including the magnetic body 10 and the pair of conductors may be referred to as a transformer-inductor 1A. Each of the components included in the transformer-inductor 1A will be described below.

[0092] The magnetic body 10, the first inner conductor 31, and the second inner conductor 32 of the transformer inductor 1A are the same as those in the first embodiment, and therefore a description thereof will be omitted. In the example shown in the drawing, the magnetic body 10 has recesses 18a and 18b, but the magnetic body 10 of the second embodiment does not necessarily have recesses.

[0093] Each of the first conductor 21A and the second conductor 22A is formed by a conductor plate 20c having an insulating coating 20i.

[0094] The first conductor 21A has a shape that is linearly symmetrical with respect to the midline between 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 linearly symmetrical with respect to the midline between one side surface 11a and the other side surface 11b when viewed from a direction perpendicular to the side surface 11c.

[0095] The first electrical conductor 21A has a first inner conductor 31 provided inside the magnetic body 10 and a first outer conductor 41 provided outside the magnetic body 10 .

[0096] The first outer conductor 41 has a plurality of first lead portions 51 .

[0097] The plurality of first lead portions 51 include one first lead portion 51a and another first lead portion 51b. When the transformer inductor 1A is mounted on the circuit board, the first lead portion 51 is connected to the circuit board via a joining material such as solder. Each first lead portion 51 has an end connected to the first internal conductor 31 and an end opposite the end on the bottom surface 18 side. The insulating coating 20i is removed from the end of the first lead portion 51 on the bottom surface 18 side, exposing the conductor plate 20c.

[0098] The first inner conductor 31, one first lead portion 51a, and the other first lead portion 51b function as a first coil of the transformer inductor 1A.

[0099] 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 extends along a direction perpendicular to the bottom surface 18, i.e., along the one side surface 11a, toward the bottom surface 18. The first lead portion 51a is disposed closer to the one side surface 11a than the second lead portion 52a, which will be described later. In other words, the first lead portion 51a is disposed closer to the one side surface 11a than the second lead portion 52a.

[0100] The first lead portion 51a has a wide portion w1a connected to one end 31a of the first inner conductor 31 and a narrow portion n1a connected to the wide portion w1a. The width of the wide portion w1a is the same as the width of the first inner conductor 31.

[0101] The other first lead portion 51b is connected to the other end 31b of the first inner conductor 31 at the other side surface 11b of the magnetic body 10. The other first lead portion 51b 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 located closer to the other side surface 11b than the other second lead portion 52b, which will be described later. In other words, the other first lead portion 51b is located closer to the other side surface 11b than the other second lead portion 52b.

[0102] The other first lead portion 51b has a wide portion w1b connected to the other end 31b of the first inner conductor 31 and a narrow portion n1b connected to the wide portion w1b. The width of the wide portion w1b is the same as the width of the first inner conductor 31.

[0103] The second conductor 22A also has a shape that is linearly symmetrical with respect to the midline between one side 11a and the other side 11b when viewed from a direction perpendicular to the top surface 19, and also has a shape that is linearly symmetrical with respect to the midline between one side 11a and the other side 11b when viewed from a direction perpendicular to the side 11c.

[0104] The second electrical conductor 22A has a second inner conductor 32 provided inside the magnetic body 10 and a second outer conductor 42 provided outside the magnetic body 10 .

[0105] The second outer conductor 42 has a plurality of second lead portions 52 .

[0106] The plurality of second lead portions 52 include one second lead portion 52a and another second lead portion 52b. When the transformer inductor 1A is mounted on the circuit board, the second lead portion 52 is connected to the circuit board via a joining material such as solder. Each second lead portion 52 has an end connected to the second internal conductor 52 and an end opposite the end on the bottom surface 18 side. The insulating coating 20i is removed from the end of the second lead portion 52 on the bottom surface 18 side, exposing the conductor plate 20c.

[0107] The second inner conductor 32, one second lead portion 52a, and the other second lead portion 52b function as a second coil of the transformer inductor 1A.

[0108] One of the second lead portions 52a is connected to one end 32a of the second internal conductor 32 at one side surface 11a of the magnetic body 10. One of the second lead portions 52a extends along a direction perpendicular to the bottom surface 18, i.e., along one side surface 11a, toward the bottom surface 18. One of the second lead portions 52a is disposed outside one of the first lead portions 51a.

[0109] The second lead portion 52a has a wide portion w2a connected to one end 32a of the second inner conductor 32 and a narrow portion n2a connected to the wide portion w2a. The width of the wide portion w2a is the same as the width of the second inner conductor 32. The wide portion w1a of the first lead portion 51a and the wide portion w2a of the second lead portion 52a are the same length, and the wide portion w1a of the first lead portion 51a and the wide portion w2a of the second lead portion 52a overlap each other when viewed from a direction perpendicular to one side surface 11a.

[0110] That is, the first lead portion 51 a and the second lead portion 52 a at least partially overlap each other when viewed from a direction perpendicular to the side surface 11 a. In other words, the first lead portion 51 a and the second lead portion 52 a at least partially face each other in the direction perpendicular to the side surface 11 a.

[0111] The other second lead portion 52b is connected to the other end 32b of the second inner conductor 32 at the other side surface 11b of the magnetic body 10. The other second lead portion 52b 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 second lead portion 52b is positioned outward of the other first lead portion 51b.

[0112] The other second lead portion 52b has a wide portion w2b connected to the other end 32b of the second inner conductor 32 and a narrow portion n2b connected to the wide portion w2b. The width of the wide portion w2b is the same as the width of the second inner conductor 32. The wide portion w1b of the other first lead portion 51b and the wide portion w2b of the other second lead portion 52b have the same length, and the wide portion w1b of the other first lead portion 51b and the wide portion w2b of the other second lead portion 52b overlap each other when viewed from a direction perpendicular to the other side surface 11b.

[0113] That is, 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 the direction perpendicular to the other side surface 11b.

[0114] 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 of the transformer inductor 1A to be improved.

[0115] [Effects, etc.] The coupling coefficient, etc. of the above-described transformer-inductor 1A will be described with reference to FIG.

[0116] Fig. 12 is a diagram showing the coupling coefficients and the like of the inductor 1A of the embodiment 2 and the inductor of the comparative example 2. Note that Fig. 12(b) is a graph of the table shown in Fig. 12(a).

[0117] 12A also shows the self-inductance L, short-circuit inductance Ls, and DC resistance DCR of the first conductor 21A, as well as the self-inductance L, short-circuit inductance Ls, and DC resistance DCR of the second conductor 22A. The coupling coefficient k shown in the figure is derived using the above-mentioned (Equation 1). Note that 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 21A.

[0118] Fig. 12 shows the coupling coefficient k when the facing ratio between the first lead portion 51 and the second lead portion 52 is changed. Note that the coupling coefficient k shown in Fig. 12 is a value when the thickness of the insulating coating 20i is 15 µm. As shown in Fig. 12, in the inductor 1A of the second embodiment as well, the coupling coefficient k increases as the facing ratio Ro increases. Furthermore, the DC resistance decreases as the facing ratio Ro increases.

[0119] Here, in order to explain the effect of the transformer-inductor 1A of the second embodiment, a transformer-inductor of a second comparative example will be explained.

[0120] In the transformer inductor of Comparative Example 2, the opposing ratio Ro of the first lead portion 51 and the second lead portion 52 is 0%. In Comparative Example 2, the first conductor 21A has L = 20.80 nH, Ls = 2.12 nH, and DCR = 2.18 mΩ, and the second conductor 22A has L = 20.55 nH, Ls = 2.09 nH, and DCR = 2.86 mΩ. The coupling coefficient k of the transformer inductor of Comparative Example 2 is calculated to be k = 0.948 according to Equation 1.

[0121] In contrast, the transformer inductor 1A of embodiment 2 has a coupling coefficient k=0.950 when the opposing ratio Ro is 10%, and a coupling coefficient k=0.971 when the opposing ratio Ro is 80%, both of which are higher than the coupling coefficient k in comparative example 2.

[0122] In this way, by setting the opposing ratio Ro of the transformer inductor 1A to be 10% or more and 80% or less, it is possible to make the coupling coefficient k higher than that of the transformer inductor of Comparative Example 2. The opposing ratio Ro is set to be 80% or less in order to avoid electrical contact with the opposing conductor when the transformer inductor 1A is mounted on a circuit board.

[0123] Furthermore, in the transformer inductor 1A, the coupling coefficient k can be further increased by setting the opposing ratio Ro to be 20% or more and 80% or less. For example, by setting the opposing ratio Ro to be 20% or more, the short-circuit inductance Ls, which is leakage inductance, can be set to approximately 2 nH or less.

[0124] Third Embodiment [Configuration of Inductor] The configuration of an inductor 1B according to a third embodiment will be described with reference to Fig. 13 and Fig. 14. In the third embodiment, an example will be described in which the arrangements of the other first terminal portion 61b and the other second terminal portion 62b are reversed.

[0125] Fig. 13 is a perspective view of an inductor 1B according to embodiment 3. Fig. 14 is a perspective view showing a pair of conductors included in inductor 1B. Note that in Fig. 14, illustration of insulating coating 20i is omitted.

[0126] The inductor 1B shown in Figures 13 and 14 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 21B and a second conductor 22B. The first conductor 21B and the second conductor 22B are insulated from each other and face each other inside the magnetic body 10. In the inductor 1B of this embodiment, the first conductor 21B and the second conductor 22B face each other outside the magnetic body 10, which makes it possible to improve the coupling coefficient.

[0127] Hereinafter, the inductor 1B including the magnetic body 10 and the pair of conductors may be referred to as a transformer-inductor 1B. Each of the components included in the transformer-inductor 1B will be described below.

[0128] The magnetic body 10, the first internal conductor 31 and the second internal conductor 32 are the same as those in the first embodiment, and therefore the description thereof will be omitted.

[0129] Each of the first conductor 21B and the second conductor 22B is formed by a conductor plate 20c having an insulating coating 20i.

[0130] The first conductor 21B has a shape that is point-symmetric with respect to the center of the top surface 19 when viewed in a direction perpendicular to the top surface 19.

[0131] The first electrical conductor 21B has a first inner conductor 31 provided inside the magnetic body 10 and a first outer conductor 41 provided outside the magnetic body 10 .

[0132] The first outer conductor 41 has a plurality of first lead portions 51 and a plurality of first terminal portions 61 .

[0133] The plurality of first terminals 61 have one first terminal 61a and the other first terminal 61b.

[0134] The first lead portions 51 include one first lead portion 51 a and another first lead portion 51 b. The first inner conductor 31, the one first lead portion 51 a, and the other first lead portion 51 b function as a first coil of the transformer inductor 1B.

[0135] 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 extends along a direction perpendicular to the bottom surface 18, i.e., along the one side surface 11a, toward the bottom surface 18. The first lead portion 51a is disposed closer to the one side surface 11a than the second lead portion 52a, which will be described later. In other words, the first lead portion 51a is disposed closer to the one side surface 11a than the second lead portion 52a.

[0136] The first lead portion 51a has a wide portion w1a connected to one end 31a of the first inner conductor 31 and a narrow portion n1a connected to the wide portion w1a. The width of the wide portion w1a is the same as the width of the first inner conductor 31.

[0137] One first lead portion 51a has an end connected to one end 31a of the first internal conductor 31 and an end opposite the end on the bottom surface 18 side. One first terminal portion 61a is connected to the end of one first lead portion 51a on the bottom surface 18 side. One first terminal portion 61a is bent to face the bottom surface 18, and at least a portion of it is housed in one recess 18a.

[0138] The other first lead portion 51b is connected to the other end 31b of the first inner conductor 31 at the other side surface 11b of the magnetic body 10. The other first lead portion 51b 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 located closer to the other side surface 11b than the other second lead portion 52b, which will be described later. In other words, the other first lead portion 51b is located closer to the other side surface 11b than the other second lead portion 52b.

[0139] The other first lead portion 51b has a wide portion w1b connected to the other end 31b of the first inner conductor 31 and a narrow portion n1b connected to the wide portion w1b. The width of the wide portion w1b is the same as the width of the first inner conductor 31.

[0140] In addition, the narrow portion n1a of one first draw-out portion 51a and the narrow portion n1b of the other first draw-out portion 51b are located opposite each other in a direction perpendicular to the side surface 11a in embodiment 1, but in embodiment 3 they are located in positions that do not face each other.

[0141] The other first lead portion 51b has an end portion connected to the other end 31b of the first internal conductor 31 and an end portion opposite the end portion on the bottom surface 18 side. The other first terminal portion 61b is connected to the end portion of the other first lead portion 51b on the bottom surface 18 side. The other first terminal portion 61b is bent to face the bottom surface 18, and at least a portion of it is housed in the other recess 18b.

[0142] The second conductor 22B also has a shape that is point-symmetric with respect to the center of the top surface 19 when viewed in a direction perpendicular to the top surface 19.

[0143] The second electrical conductor 22B has a second inner conductor 32 provided inside the magnetic body 10 and a second outer conductor 42 provided outside the magnetic body 10 .

[0144] The second outer conductor 42 has a plurality of second lead portions 52 and a plurality of second terminal portions 62 .

[0145] The plurality of second terminals 62 include one second terminal 62a and the other second terminal 62b.

[0146] The second lead portions 52 include one second lead portion 52 a and another second lead portion 52 b. The second inner conductor 32, the one second lead portion 52 a, and the other second lead portion 52 b function as a second coil of the transformer inductor 1B.

[0147] One of the second lead portions 52a is connected to one end 32a of the second internal conductor 32 at one side surface 11a of the magnetic body 10. One of the second lead portions 52a extends along a direction perpendicular to the bottom surface 18, i.e., along one side surface 11a, toward the bottom surface 18. One of the second lead portions 52a is disposed outside one of the first lead portions 51a.

[0148] The second lead portion 52a has a wide portion w2a connected to one end 32a of the second inner conductor 32 and a narrow portion n2a connected to the wide portion w2a. The width of the wide portion w2a is the same as the width of the second inner conductor 32. The wide portion w1a of the first lead portion 51a and the wide portion w2a of the second lead portion 52a are the same length, and the wide portion w1a of the first lead portion 51a and the wide portion w2a of the second lead portion 52a overlap each other when viewed from a direction perpendicular to one side surface 11a.

[0149] The first lead portion 51 a and the second lead portion 52 a at least partially overlap each other when viewed from a direction perpendicular to the side surface 11 a. In other words, the first lead portion 51 a and the second lead portion 52 a at least partially face each other in the direction perpendicular to the side surface 11 a.

[0150] One second lead portion 52a has an end connected to one end 32a of the second internal conductor 32 and an end opposite the end on the bottom surface 18 side. One second terminal portion 62a is connected to the end of one second lead portion 52a on the bottom surface 18 side. 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. Note that one first terminal portion 61a and the other first terminal portion 61b are arranged on the diagonal of the rectangular first internal conductor 31 when viewed from a direction perpendicular to the top surface 19.

[0151] The other second lead portion 52b is connected to the other end 32b of the second inner conductor 32 at the other side surface 11b of the magnetic body 10. The other second lead portion 52b 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 second lead portion 52b is positioned outward of the other first lead portion 51b.

[0152] The other second lead portion 52b has a wide portion w2b connected to the other end 32b of the second inner conductor 32 and a narrow portion n2b connected to the wide portion w2b. The width of the wide portion w2a is the same as the width of the second inner conductor 32. The wide portion w1b of the other first lead portion 51b and the wide portion w2b of the other second lead portion 52b have the same length, and the wide portion w1b of the other first lead portion 51b and the wide portion w2b of the other second lead portion 52b overlap each other when viewed from a direction perpendicular to the other side surface 11b.

[0153] In addition, the narrow portion n2a of one second draw-out portion 52a and the narrow portion n2b of the other second draw-out portion 52b are located opposite each other in a direction perpendicular to the side surface 11a in embodiment 1, but in embodiment 3 they are located in positions that do not face each other.

[0154] 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 the direction perpendicular to the other side surface 11b.

[0155] The other second lead portion 52b has an end portion connected to the other end 32b of the second internal conductor 32 and an end portion on the bottom surface 18 side opposite the end portion. The other second terminal portion 62b is connected to the end portion on the bottom surface 18 side of the other second lead portion 52b. The other second terminal portion 62b is bent to face the bottom surface 18, and at least a portion of it is housed in the other recess 18b. Note that the one second terminal portion 62a and the other second terminal portion 62b are arranged on diagonals of the rectangular second internal conductor 32 when viewed from a direction perpendicular to the top surface 19.

[0156] As described above, in the transformer inductor 1B 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 of the transformer inductor 1B to be improved.

[0157] [Effects, etc.] The coupling coefficient, etc. of the above-described transformer-inductor 1B will be described with reference to FIG.

[0158] Fig. 15 is a diagram showing the coupling coefficients and the like of the inductor 1B of the third embodiment and the inductor of the comparative example 3. Note that Fig. 15(b) is a graph of the table shown in Fig. 15(a).

[0159] 15A also shows the self-inductance L, short-circuit inductance Ls, and DC resistance DCR of the first conductor 21B, as well as the self-inductance L, short-circuit inductance Ls, and DC resistance DCR of the second conductor 22B. The coupling coefficient k shown in the figure is derived using the above-mentioned (Equation 1). Note that 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 21B.

[0160] Fig. 15 shows the coupling coefficient k when the facing ratio between the first lead portion 51 and the second lead portion 52 is changed. Note that the coupling coefficient k shown in Fig. 15 is a value when the thickness of the insulating coating 20i is 15 μm. As shown in Fig. 15, in the transformer inductor 1B of embodiment 3 as well, the coupling coefficient k increases as the facing ratio Ro increases. Furthermore, the DC resistance decreases as the facing ratio Ro increases.

[0161] Here, in order to explain the effect of the transformer-inductor 1B of the third embodiment, a transformer-inductor of a third comparative example will be explained.

[0162] In the transformer inductor of Comparative Example 3, the opposing ratio Ro of the first lead portion 51 and the second lead portion 52 is 0%. In Comparative Example 3, the first conductor 21B has L = 21.70 nH, Ls = 2.26 nH, and DCR = 2.13 mΩ, and the second conductor 22B has L = 21.43 nH, Ls = 2.23 nH, and DCR = 2.81 mΩ. The coupling coefficient k of the transformer inductor of Comparative Example 3 is calculated to be k = 0.946 according to (Equation 1).

[0163] In contrast, the transformer inductor 1B of embodiment 3 has a coupling coefficient k=0.949 when the opposing ratio Ro is 10%, and a coupling coefficient k=0.969 when the opposing ratio Ro is 80%, both of which are higher than the coupling coefficient k in comparative example 3.

[0164] In this way, by setting the opposing ratio Ro of the transformer inductor 1B to be 10% or more and 80% or less, it is possible to make the coupling coefficient k higher than that of the transformer inductor of Comparative Example 3. The opposing ratio Ro is set to be 80% or less in order to avoid electrical contact with the opposing conductor when the transformer inductor 1B is mounted on a circuit board.

[0165] Furthermore, in the transformer inductor 1B, the coupling coefficient k can be further increased by setting the opposing ratio Ro to be 20% or more and 80% or less. For example, by setting the opposing ratio Ro to be 20% or more, the short-circuit inductance Ls, which is leakage inductance, can be set to approximately 2 nH or less.

[0166] Fourth Embodiment [Configuration of Inductor] The configuration of an inductor 1C according to a fourth embodiment will be described with reference to Fig. 16 and Fig. 17. In the fourth embodiment, an example will be described in which the width of the first terminal portion 61 and the width of the second terminal portion 62 are wide.

[0167] Fig. 16 is a perspective view of an inductor 1C according to embodiment 4. Fig. 17 is a perspective view showing a pair of conductors included in the inductor 1C. Note that in Fig. 17, the insulating coating 20i is not shown.

[0168] The inductor 1C shown in Figures 16 and 17 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 21C and a second conductor 22C. The first conductor 21C and the second conductor 22C are insulated from each other and face each other inside the magnetic body 10. In the inductor 1C of this embodiment, the first conductor 21C and the second conductor 22C face each other outside the magnetic body 10, which makes it possible to improve the coupling coefficient.

[0169] Hereinafter, the inductor 1C including the magnetic body 10 and the pair of conductors may be referred to as a transformer inductor 1C. Each of the components included in the transformer inductor 1C will be described below.

[0170] The magnetic body 10, the first internal conductor 31 and the second internal conductor 32 are the same as those in the first embodiment, and therefore the description thereof will be omitted.

[0171] Each of the first conductor 21C and the second conductor 22C is formed by a conductor plate 20c having an insulating coating 20i.

[0172] The first conductor 21C has a shape that is point-symmetric with respect to the center of the top surface 19 when viewed in a direction perpendicular to the top surface 19.

[0173] The first electrical conductor 21C has a first inner conductor 31 provided inside the magnetic body 10 and a first outer conductor 41 provided outside the magnetic body 10 .

[0174] The first outer conductor 41 has a plurality of first lead portions 51 and a plurality of first terminal portions 61 .

[0175] The plurality of first terminals 61 have one first terminal 61a and the other first terminal 61b.

[0176] The first lead portions 51 include one first lead portion 51 a and another first lead portion 51 b. The first inner conductor 31, the one first lead portion 51 a, and the other first lead portion 51 b function as a first coil of the transformer inductor 1C.

[0177] 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 extends along a direction perpendicular to the bottom surface 18, i.e., along the one side surface 11a, toward the bottom surface 18 and the side surface 11d. The first lead portion 51a is disposed closer to the one side surface 11a than the second lead portion 52a, which will be described later. In other words, the first lead portion 51a is disposed closer to the one side surface 11a than the second lead portion 52a.

[0178] One of the first lead portions 51a has a stepped shape. The first lead portion 51a has a first extending portion connected to one end 31a of the first internal conductor 31 and extending partway toward the bottom surface 18, a second extending portion connected to an end of the first extending portion on the bottom surface 18 side and extending partway toward the side surface 11d, and a third extending portion connected to an end of the second extending portion on the bottom surface 18 side closer to the side surface 11d, extending toward the bottom surface 18, and connected to one of the first terminal portions 61a. Thus, the first extending portion has an end connected to one end 31a of the first internal conductor 31 and an end on the bottom surface 18 side opposite the end. The second extending portion has an end connected to the end of the first extending portion on the bottom surface 18 side and an end on the bottom surface 18 side opposite the end of the first extending portion and closer to the side surface 11d. The third extension portion has an end portion connected to an end portion of the second extension portion closer to the bottom surface 18 and closer to the side surface 11d, and an end portion on the opposite side of the second extension portion closer to the bottom surface 18. The width of the first extension portion is the same as the width of the first internal conductor 31. The width of the third extension portion is the same as the width of one of the first terminal portions 61a. The width of one of the first terminal portions 61a is wider than the width of one of the first terminal portions 61a in the third embodiment.

[0179] 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 bent to face the bottom surface 18, and at least a portion of it is housed in one of the recesses 18a.

[0180] 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 extends along a direction perpendicular to the bottom surface 18, i.e., along the other side surface 11b, toward the bottom surface 18 and the side surface 11c. The other first lead portion 51b is located closer to the other side surface 11b than the other second lead portion 52b, which will be described later. In other words, the other first lead portion 51b is located closer to the other side surface 11b than the other second lead portion 52b.

[0181] The other first lead portion 51b has a stepped shape. The other first lead portion 51b has a first extending portion connected to the other end 31b of the first internal conductor 31 and extending partway toward the bottom surface 18, a second extending portion connected to the end of the first extending portion on the bottom surface 18 side and extending partway toward the side surface 11c, and a third extending portion connected to an end of the second extending portion on the bottom surface 18 side closer to the side surface 11c, extending toward the bottom surface 18, and connected to the other first terminal portion 61b. Thus, the first extending portion has an end connected to the other end 31b of the first internal conductor 31 and an end on the bottom surface 18 side opposite the first extending portion. The second extending portion has an end connected to the end of the first extending portion on the bottom surface 18 side and an end on the bottom surface 18 side opposite the first extending portion. The third extension portion has an end portion connected to an end portion of the second extension portion closer to the bottom surface 18 and the side surface 11c, and an end portion opposite the end portion, closer to the bottom surface 18. The width of the first extension portion is the same as the width of the first internal conductor 31. The width of the other first terminal portion 61b is wider than the width of the other first terminal portion 61b of the third embodiment.

[0182] The other first terminal portion 61b is connected to the end of the other first lead portion 51b on the bottom surface 18 side. The other first terminal portion 61b is bent to face the bottom surface 18, and at least a portion of it is housed in the other recess 18b.

[0183] The second conductor 22C also has a shape that is point-symmetric when viewed from a direction perpendicular to the top surface 19.

[0184] The second electrical conductor 22C has a second inner conductor 32 provided inside the magnetic body 10 and a second outer conductor 42 provided outside the magnetic body 10 .

[0185] The second outer conductor 42 has a plurality of second lead portions 52 and a plurality of second terminal portions 62 .

[0186] The plurality of second terminals 62 include one second terminal 62a and the other second terminal 62b.

[0187] The second lead portions 52 include one second lead portion 52 a and another second lead portion 52 b. The second inner conductor 32, the one second lead portion 52 a, and the other second lead portion 52 b function as a second coil of the transformer inductor 1C.

[0188] One 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. One second lead portion 52a extends along a direction perpendicular to the bottom surface 18, i.e., along one side surface 11a, toward the bottom surface 18 and the side surface 11c. One second lead portion 52a is disposed outside one first lead portion 51a.

[0189] One of the second lead portions 52a has a stepped shape. The one of the second lead portions 52a has a first extending portion connected to one end 32a of the second internal conductor 32 and extending partway toward the bottom surface 18, a second extending portion connected to an end of the first extending portion on the bottom surface 18 side and extending partway toward the side surface 11c, and a third extending portion connected to an end of the second extending portion on the bottom surface 18 side closer to the side surface 11c, extending toward the bottom surface 18, and connected to one of the second terminal portions 62a. Thus, the first extending portion has an end connected to one end 32a of the second internal conductor 32 and an end on the bottom surface 18 side opposite the first extending portion. The second extending portion has an end connected to the end of the first extending portion on the bottom surface 18 side and an end on the bottom surface 18 side opposite the first extending portion and closer to the side surface 11c. The third extension portion has an end portion connected to an end portion of the second extension portion closer to the bottom surface 18 and closer to the side surface 11c, and an end portion on the bottom surface 18 side opposite the end portion. The width of the first extension portion is the same as the width of the second internal conductor 32. The width of the third extension portion is the same as the width of one of the second terminal portions 62a. The width of one of the second terminal portions 62a is narrower than the width of one of the first terminal portions 61a. The width of one of the second terminal portions 62a is also wider than the width of one of the second terminal portions 62a in embodiment 3.

[0190] The first lead portion 51 a and the second lead portion 52 a at least partially overlap each other when viewed from a direction perpendicular to the side surface 11 a. In other words, the first lead portion 51 a and the second lead portion 52 a at least partially face each other in the direction perpendicular to the side surface 11 a.

[0191] One of the second terminal portions 62a is connected to the end of one of the second lead portions 52a on the bottom surface 18 side. One of the second terminal portions 62a is bent to face the bottom surface 18, and at least a portion of it is housed in one of the recesses 18a.

[0192] 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 extends along a direction perpendicular to the bottom surface 18, i.e., along the other side surface 11b, toward the bottom surface 18 and the side surface 11d. The other second lead portion 52b is positioned outward of the other first lead portion 51b.

[0193] The other second lead portion 52b has a stepped shape. The other second lead portion 52b has a first extending portion connected to the other end 32b of the second internal conductor 32 and extending partway toward the bottom surface 18, a second extending portion connected to the end of the first extending portion on the bottom surface 18 side and extending partway toward the side surface 11d, and a third extending portion connected to an end of the second extending portion on the bottom surface 18 side closer to the side surface 11d, extending toward the bottom surface 18, and connected to the other second terminal portion 62b. Thus, the first extending portion has an end connected to the other end 32b of the second internal conductor 32 and an end on the bottom surface 18 side opposite the first extending portion. The second extending portion has an end connected to the end of the first extending portion on the bottom surface 18 side and an end on the bottom surface 18 side opposite the first extending portion and closer to the side surface 11d. The third extension portion has an end portion connected to an end portion of the second extension portion closer to the bottom surface 18 and closer to the side surface 11d, and an end portion on the bottom surface 18 side opposite the end portion. The width of the first extension portion is the same as the width of the second internal conductor 32. The width of the third extension portion is the same as the width of the other second terminal portion 62b. The width of the other second terminal portion 62b is narrower than the width of the other first terminal portion 61b. The width of the other second terminal portion 62b is also wider than the width of the other second terminal portion 62b in embodiment 3.

[0194] 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 the direction perpendicular to the other side surface 11b.

[0195] The other second terminal portion 62b is connected to the end of the other second lead portion 52b on the bottom surface 18 side. The other second terminal portion 62b is bent to face the bottom surface 18, and at least a portion of it is housed in the other recess 18b.

[0196] As described above, in the transformer inductor 1C 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. Therefore, the first lead portion 51 and the second lead portion 52 can be coupled to each other outside the magnetic body 10. This can improve the coupling coefficient of the transformer inductor 1C.

[0197] For example, in the transformer inductor 1C of the fourth embodiment, when the opposing ratio Ro of the first lead portion 51 and the second lead portion 52 is 62.5%, the first conductor 21C has L = 23.36 nH, Ls = 2.08 nH, and DCR = 1.08 mΩ, and the second conductor 22C has L = 23.20 nH, Ls = 2.06 nH, and DCR = 1.88 mΩ. When the opposing ratio Ro is 62.5%, the coupling coefficient k of the transformer inductor 1C of the fourth embodiment is k = 0.955.

[0198] (Summary) Inductors according to the present embodiment will be exemplified below.

[0199] 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 (e.g., 11a) 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 outer conductor 41 has a first lead portion 51 connected to the first inner conductor 31 at a side surface (e.g., 11a) and extending toward the bottom surface 18, and the second outer conductor 42 has a second lead portion 52 connected to the second inner conductor 32 at a side surface (e.g., 11a) and extending toward the bottom surface 18. 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 (e.g., 11a).

[0200] According to this configuration, the first lead portion 51 and the second lead portion 52 can be coupled inside and outside the magnetic body 10. This can improve the coupling coefficient of the inductor.

[0201] The inductor of Example 2 is the inductor described in Example 1, except that the side surfaces include one side surface 11a and the other side surface 11b that face each other. Each of the first inner conductor 31 and the second inner conductor 32 extends in a direction perpendicular to the one side surface 11a and has one end connected to the one side surface 11a and the other end connected to the other side surface 11b. The first lead portion 51 has one first lead portion 51a connected to 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 at least partially overlap each other when viewed in a direction perpendicular to the one side surface 11a. 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.

[0202] 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 portion 51b and the other of the second lead portion 52b can be coupled to each other outside the magnetic body 10. This can improve the coupling coefficient of the inductor.

[0203] The inductor of Example 3 is the inductor described in Example 2, in which the first inner conductor 31 is arranged closer to the bottom surface 18 than the second inner conductor 32, 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. That is, the first inner conductor 31 may be arranged closer to the bottom surface 18 than the second inner conductor 32, one first lead portion 51a may be arranged closer to one side surface 11a than one second lead portion 52a, and the other first lead portion 51b may be arranged closer to the other side surface 11b than the other second lead portion 52b.

[0204] This configuration allows the first inner conductor 31, the first lead portion 51 a, and the other first lead portion 51 b to be coupled to the second inner conductor 32, the second lead portion 52 a, and the other second lead portion 52 b, thereby improving the coupling coefficient of the inductor.

[0205] The inductor of Example 4 is the inductor described in Example 3, and the distance d1 between the first inner conductor 31 and the bottom surface 18 may be longer than the distance d2 between the second inner conductor 32 and the top surface 19 .

[0206] This configuration makes it possible to increase the effective cross-sectional area of ​​the magnetic path of each of the first coil formed by the first inner conductor 31, the one first lead portion 51a, and the other first lead portion 51b, and the second coil formed by the second inner conductor 32, the one second lead portion 52a, and the other second lead portion 52b. This increases the self-inductance of the inductor. Furthermore, increasing the self-inductance improves the coupling coefficient.

[0207] The inductor of Example 5 is an inductor described in any of Examples 1 to 4, wherein the first outer conductor 41 further has a first terminal portion 61 connected to the end of the first extension portion 51 on the bottom surface 18 side, and the second outer conductor 42 further has a second terminal portion 62 connected to the end of the second extension portion 52 on the bottom surface 18 side.

[0208] This configuration makes it possible to improve connection reliability when connecting the inductor to a circuit board using, for example, solder.

[0209] The inductor of Example 6 is the inductor according to any one of Examples 2 to 4, and the first lead portion 51 and the second lead portion 52 may be at least partially opposed to each other in a direction perpendicular to one side surface 11a.

[0210] According to this configuration, the first lead portion 51 and the second lead portion 52 can be coupled to each other outside the magnetic body 10. This can improve the coupling coefficient of the inductor.

[0211] The inductor of Example 7 is the inductor according to any one of Examples 3 to 6, wherein first lead portion 51 and second lead portion 52 each extend in a direction perpendicular to bottom surface 18. If the length of first lead portion 51 in the direction perpendicular to bottom surface 18 is defined as H1, the length over which first lead portion 51 and second lead portion 52 face each other in the direction perpendicular to bottom surface 18 is defined as Ho, and the facing ratio between first lead portion 51 and second lead portion 52 is defined as Ro, and the facing ratio is calculated as Ro(%) = (Ho / H1) × 100, then Ro may be 10% or more and 80% or less.

[0212] As described above, by setting the facing ratio between the first lead portion 51 and the second lead portion 52, the coupling coefficient of the inductor can be improved.

[0213] The inductor of Example 8 is the inductor according to any one of Examples 1 to 7, wherein the conductor is formed of a conductor plate 20c having an insulating coating 20i. In a region where the first inner conductor 31 and the second inner conductor 32 face each other, an opposing distance d o between the conductor plate 20c included in the first inner conductor 31 and the conductor plate 20c included in the second inner conductor 32 may be 20 μm or more and 50 μm or less.

[0214] As described above, by setting the opposing distance do between the conductive plate 20c included in the first inner conductor 31 and the conductive plate 20c included in the second inner conductor 32, the coupling coefficient of the inductor can be improved.

[0215] The inductor of Example 9 is an inductor described in any one of Examples 2 to 4, 6 and 7, and when viewed from a direction perpendicular to one side surface 11a, the width of the wide portion of the first extension portion 51 connected to the first internal conductor 31 and the width of the wide portion of the second extension portion 52 connected to the second internal conductor 32 may be the same.

[0216] This allows the opposing areas of the wide portions to be increased, thereby improving the coupling coefficient of the inductor.

[0217] The inductor of Example 10 is an inductor described in any one of Examples 2 to 4, 6 and 7, and when viewed from a direction perpendicular to one side surface 11a, the width of the wide portion of the first extension portion 51 connected to the first internal conductor 31 and the width of the wide portion of the second extension portion 52 connected to the second internal conductor 32 may be different.

[0218] As a result, even if the position of the wide portion is shifted, the first drawer portion 51 and the second drawer portion 52 will always face each other in the narrower area, thereby reducing the variation in the coupling coefficient caused by the positional shift of the wide portion.

[0219] The inductor of Example 11 is the inductor described in any one of Examples 1 to 10, wherein the magnetic body 10 includes a mixture of magnetic material powder and a binder, and the magnetic body 10 and the pair of conductors may be integrally molded by pressure.

[0220] By pressure-molding the magnetic body 10 and the pair of conductors in this manner, the coupling coefficient of the inductor can be improved, and the self-inductance and DC bias characteristics can also be improved.

[0221] (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.

[0222] 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.

[0223] The inductor according to the present invention can provide an inductor with a high coupling coefficient, and is therefore industrially useful.

[0224] REFERENCE SIGNS LIST 1, 1A, 1B, 1C 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, 21A, 21B, 21C First conductor 22, 22A, 22B, 22C 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 The other second terminal portion d1, d2 Distance do Opposing distance H1 Length of first lead portion Ho Opposing length Ro Opposing ratio w1a, w1b, w2a, w2b Wide portion

Claims

1. An inductor comprising: 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 in a direction perpendicular to the bottom surface, the first external conductor has a first lead-out portion connected to the first internal conductor at the side surface and extending toward the bottom surface, the second external conductor has a second lead-out portion connected to the second internal conductor at the side surface and extending toward the bottom surface, and the first lead-out portion and the second lead-out portion at least partially overlap each other when viewed in a direction perpendicular to the side surface.

2. The inductor according to claim 1, wherein the side surfaces have one side surface and the other side surface facing each other, the first inner conductor and the second inner conductor each extend in a direction perpendicular to the one side surface and have 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 inner conductor and the other first lead-out portion connected to the other end of the first inner conductor, the second lead-out portion has one second lead-out portion connected to one end of the second inner conductor and the other second lead-out portion connected to the other end of the second inner conductor, the one first lead-out portion and the one second lead-out portion at least partially overlap each other when viewed in the 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 in the direction perpendicular to the other side surface.

3. An inductor as described in claim 2, wherein the first inner conductor is positioned closer to the bottom surface than the second inner conductor, the one first lead-out portion is positioned closer to the one side surface than the one second lead-out portion, and the other first lead-out portion is positioned closer to the other side surface than the other second lead-out portion.

4. The inductor according to claim 3, wherein the distance between the first internal conductor and the bottom surface is longer than the distance between the second internal conductor and the top surface.

5. An inductor as described in any one of claims 1 to 4, wherein the first outer conductor further has a first terminal portion connected to the end of the first lead-out portion on the bottom surface side, and the second outer conductor further has a second terminal portion connected to the end of the second lead-out portion on the bottom surface side.

6. The inductor according to any one of claims 2 to 4, wherein at least a portion of the first lead portion and the second lead portion oppose each other in a direction perpendicular to the one side surface.

7. The inductor according to claim 3 or 4, wherein each of the first and second lead-out portions extends in a direction perpendicular to the bottom surface, H1 is a length of the first lead-out portion in the direction perpendicular to the bottom surface, Ho is a length over which the first and second lead-out portions face each other in the direction perpendicular to the bottom surface, Ro is an opposing ratio between the first and second lead-out portions, and when the opposing ratio is defined as being calculated by Ro(%) = (Ho / H1) x 100, Ro is 10% or more and 80% or less.

8. An inductor according to any one of claims 1 to 4, wherein the conductor is formed by a conductive plate having an insulating coating, and in a region where the first internal conductor and the second internal conductor face each other, the facing distance between the conductive plate included in the first internal conductor and the conductive plate included in the second internal conductor is 20 μm or more and 50 μm or less.

9. An inductor as described in any one of claims 2 to 4, wherein, when viewed from a direction perpendicular to said one side surface, the width of the wide portion of the first lead-out portion connected to the first inner conductor and the width of the wide portion of the second lead-out portion connected to the second inner conductor are the same.

10. An inductor as described in any one of claims 2 to 4, wherein when viewed from a direction perpendicular to the one side surface, the width of the wide portion of the first extension portion connected to the first inner conductor and the width of the wide portion of the second extension portion connected to the second inner conductor are different.

11. An inductor according to any one of claims 1 to 4, wherein the magnetic body contains a mixture of magnetic material powder and a binder, and the magnetic body and the pair of conductors are integrally molded by applying pressure.

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