Inductor and method for manufacturing inductor

Abstract

An inductor (100) is provided with a magnetic core (10) having a bottom surface (11) (first surface) and a coil element (20) comprising a flat wire, the coil element (20) having a wound coil part (21) and a first lead-out part (22) connected to the coil part (21) and one of the two end parts (first end part (25)), the first lead-out part (22) being provided with two or more bent parts (31) bent in the direction in which the flat wire extends, and the first lead-out part (22) being provided with two or more second lead-out parts (31) extending in the direction in which the flat wire extends. The coil portion (21) has two or more curved portions (31) having a dimple (32) on the surface of the flat wire in each of the curved portions (31), and a notch structure (33) recessed toward the inside of the flat wire in the dimple (32) is formed in the curved portion (31) closest to the coil portion (21) among the two or more curved portions (31). The indentation depth of the indentation structure (33) on one end side of the indentation (32) closer to the winding axis (B) of the coil part (21) is greater than the indentation depth of the indentation structure on the other end side of the indentation (32) farther from the winding axis (B) of the coil part (21).

Description

Technical Field

[0001] The present disclosure relates to an inductor and a method for manufacturing an inductor. Background Art

[0002] An inductor is a passive element that stores electric energy as magnetic energy, for example, in a DC-DC converter device, etc., for the purpose of stepping up or down a power supply voltage and smoothing a direct current. The inductor is mounted on the surface of a circuit board, etc. For example, Patent Document 1 discloses an inductor comprising: a main body including a magnetic material; a coil element disposed inside the main body; and a terminal metal fitting connected to the coil element. In the inductor described in Patent Document 1, the end of the coil element is exposed from the main body, and a terminal metal fitting is welded to the end of the exposed coil element.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-243685 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In addition, there are inductors that use a rectangular wire with a rectangular cross-sectional shape to form a coil element. In such a coil element formed by using a rectangular wire, different parts of the wire material are close to each other during the bending process for forming the coil element, and there is a case where the insulation between these parts is reduced, and there is a problem that the reliability of the inductor is reduced. In view of the above situation, the present disclosure aims to improve the reliability of the inductor.

[0008] Means for solving problems

[0009] An inductor according to one embodiment of the present disclosure comprises: a magnetic core obtained by press-forming a mixture of magnetic material powder and a binder, the magnetic core having a first surface and a second surface connected to the first surface; and a coil element having an embedded portion embedded in the magnetic core and two ends respectively connected to the embedded portion, the two ends protruding to the outside of the magnetic core at positions at the same height from the first surface, the coil element being composed of a rectangular wire having an insulating coating on the surface and having a rectangular cross-sectional shape, the embedded portion of the coil element having a coil portion wound with the rectangular wire, a first lead connected to the coil portion and one of the two ends A portion, and a second lead-out portion connected to the coil portion and the other of the two end portions, wherein the first lead-out portion is provided with two or more bent portions bent in the extension direction of the flat wire, and the two or more bent portions have indentations on the surface of the flat wire in each of the bent portions, and a notch structure is formed in the bent portion closest to the coil portion among the two or more bent portions, wherein the notch structure is sunken in the indentation toward the inside of the flat wire, and a sunken depth of one end side of the notch that is closer to the winding axis of the coil portion than a sunken depth of the other end side of the notch that is farther from the winding axis.

[0010] In addition, a method for manufacturing an inductor according to an embodiment of the present disclosure includes the following steps: a step of forming a coil element, which is a step of forming a coil element composed of a rectangular wire having an insulating coating on the surface and having a rectangular cross-sectional shape, including the following steps: forming a coil portion formed by winding a portion between two ends of the rectangular wire; and bending a first lead portion connecting one of the two ends to the coil portion twice or more to form two or more bent portions having indentations on the surface of the rectangular wire; and forming a magnetic core by press-molding a mixture of magnetic material powder and a binder, thereby forming the coil element. The coil portion and the first lead portion are buried in the magnetic core; in the process of forming the two or more bent portions, after forming a cut that is sunk into the surface of the flat wire toward the inside of the flat wire at a position corresponding to the indentation in the bent portion closest to the coil portion among the two or more bent portions, the flat wire is bent to form a notch structure sunk into the inside of the flat wire in the indentation, wherein the depth of sunken into one end side of the indentation that is closer to the winding axis of the coil portion is deeper than the depth of sunken into the other end side of the indentation that is farther from the winding axis.

[0011] Effects of the Invention

[0012] According to the present disclosure, the reliability of the inductor can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a first perspective view of the inductor according to the embodiment.

[0014] Figure 2 This is a second perspective view of the inductor according to the embodiment.

[0015] Figure 3 This is a third perspective view of the inductor according to the embodiment.

[0016] Figure 4 1 is a flowchart showing a method for manufacturing an inductor according to an embodiment.

[0017] Figure 5 This is a flowchart showing a method for forming a coil element of an inductor according to an embodiment.

[0018] Figure 6 It is a plan view for explaining the shape of the cutout according to the embodiment. DETAILED DESCRIPTION

[0019] (How this disclosure was obtained)

[0020] As described in the background technology section, in an inductor in which a coil element is formed by bending a flat wire, it is common for different parts of the wire to be close to each other. Specifically, as a coil element using a flat wire, it is assumed that a coil element having a coil portion formed by winding a flat wire in an edgewise shape is formed. Usually, when an edgewise coil portion is formed, the heights of the two end portions extending from the coil portion (the positions in the winding axis direction of the coil portion) gradually differ depending on the number of windings. In order to bury the coil element with different heights at the two end portions in the magnetic core as it is, it is necessary to design the magnetic core according to the ends with different heights.

[0021] On the other hand, from the perspective of inductor performance, it is required to fill magnetic material powder with high density, and sometimes it is required to use a powder core obtained by press-molding a mixture of magnetic material powder and a binder as the magnetic core of the inductor.

[0022] In press forming, it is difficult to control the positions of the ends before and after compression, so it is difficult to design a magnetic core that corresponds to the ends of different heights. Therefore, there is a case where the following method is adopted, that is, inside the magnetic core, the wire is bent in the lead-out portion from the coil portion to the end so that the heights of the respective ends are aligned (to become the same height). However, when the wire is bent, the metal material of the wire expands and contracts, and it is possible that the metal material on the concave side of the bend reaches a position outside the expansion compared to the original surface position of the wire.

[0023] In particular, if the wire extending from the coil portion to the outside of the magnetic core, that is, in a direction away from the coil portion, is bent so that it extends in the direction of the winding axis of the coil portion, the wires may be close to each other between the coil portion and the expanded wire because the expanded side of the metal material of the wire is toward the direction of the coil portion.

[0024] When bending a wire, a metal having a bent corner is placed at a position to form a bend dent and processed. Due to the pressure applied at this time, the insulating coating such as enamel covering the surface of the wire is damaged by tearing and peeling. As mentioned above, due to expansion, the damage to the insulating coating also spreads to the expanded portion, and the insulation performance of the expanded portion may be significantly reduced.

[0025] For this reason, the insulation between different parts of the wire, for example, between the expanded part of the wire and the coil part, is reduced. Therefore, the object of the present disclosure is to bend the wire after performing a process for controlling the expansion of the metal material due to expansion and contraction when bending the wire, thereby suppressing the approach of the wires to each other, and providing an inductor with high reliability.

[0026] In order to improve the reliability of the inductor, the present disclosure has the following structure. Hereinafter, embodiments will be described in more detail with reference to the drawings.

[0027] In addition, the embodiments described below all represent a specific example of the present disclosure. The numerical values, shapes, materials, structural elements, configuration positions of structural elements, connection methods, steps, and step sequences shown in the following embodiments are only examples, and their purpose is not to limit the present disclosure. In addition, among the structural elements in the following embodiments, structural elements not recorded in the independent technical solutions are described as arbitrary structural elements.

[0028] In addition, in this specification, terms such as parallel that indicate the relationship between elements, terms such as rectangular that indicate the shape of an element, and numerical ranges do not express only strict meanings, but rather express substantially equivalent ranges, for example, also including differences of several percentage points.

[0029] In addition, each figure is a schematic diagram that appropriately emphasizes, omits, or adjusts the ratio in order to express the present disclosure, and is not necessarily a strict illustration, and sometimes differs from the actual shape, positional relationship, and ratio. In each figure, the same reference numerals are marked for substantially the same structure, and repeated descriptions are sometimes omitted or simplified.

[0030] In addition, the X-axis, Y-axis, and Z-axis are shown in each figure as three mutually orthogonal directions, that is, these axes and axial directions along the axes are used for explanation as needed. In addition, each axis is marked for the purpose of explanation and does not limit the direction and posture of using the inductor.

[0031] In addition, in this specification, terms such as "top surface" and "bottom surface" in the structure of an inductor do not refer to the top surface (the surface on the vertically upper side) and the bottom surface (the surface on the vertically lower side) in absolute spatial recognition, but are used as terms defined by the relative positional relationship of the structural elements of the inductor.

[0032] (Implementation Method)

[0033] [Inductor Structure]

[0034] The structure of the inductor of this embodiment is described. The inductor is a passive element that stores electric energy flowing through a coil element as magnetic energy.

[0035] Figure 1 This is a first perspective view of the inductor according to the embodiment. Figure 2 is a second stereogram of the inductor. In addition, Figure 2 Yes Figure 1 The enlarged perspective view of the curved portion 31 in the region A is shown in FIG.

[0036] like Figure 1 and Figure 2 As shown, the inductor 100 includes a magnetic core 10 and a coil element 20 having a coil portion 21 and a plurality of lead portions.

[0037] The general shape of the inductor 100 is determined by the shape of the magnetic core 10, which is a rectangular powder core. In addition, the magnetic core 10 can be formed into any shape by molding. That is, according to the shape of the magnetic core 10 when it is formed, an inductor 100 of any shape can be realized. In the magnetic core 10 of this embodiment, for example, the dimension in the X-axis direction is greater than 17 mm and less than 70 mm, the dimension in the Y-axis direction is greater than 17 mm and less than 70 mm, and the dimension in the Z-axis direction is greater than 7 mm and less than 50 mm. For example, the dimension of the magnetic core 10 in the X-axis direction is 40 mm, the dimension in the Y-axis direction is greater than 40 mm, and the dimension in the Z-axis direction is 18 mm, etc.

[0038] The magnetic core 10 is the outer shell of the inductor 100, and covers a part of the coil element 20 (the embedded part 24 composed of the coil part 21 and the first lead part 22 and the second lead part 23). In other words, the embedded part 24 is embedded in the magnetic core 10. The magnetic core 10 includes a magnetic material, for example, a pressed powder magnetic core composed of a metal magnetic material powder and a resin material as a binder for bonding the magnetic material powders to each other. In addition, the magnetic core 10 can be formed using a magnetic material. For the magnetic material, ferrite can be used, or other magnetic materials can be used. For the metal magnetic material powder, a granular material having a specified element composition such as Fe-Si-Al, Fe-Si, Fe-Si-Cr or Fe-Si-Cr-B is used. In addition, for the resin material, a material such as a silicone resin is selected that insulates between the particles of the metal magnetic powder and can maintain a certain shape by bonding the particles of the metal magnetic powder.

[0039] The magnetic core 10 is, for example, in the shape of a rectangular parallelepiped. The magnetic core 10 has a bottom surface (in other words, a first surface) 11, a top surface 12 facing away from the bottom surface 11, and four side surfaces 13a, 13b, 13c, and 13d (in other words, end surfaces) connecting the bottom surface 11 and the top surface 12. In this example, an example is described in which, among the side surfaces 13a, 13b, 13c, and 13d, the side surface 13c is the second surface, and the side surfaces 13a, 13b, and 13d are the third surface. In addition, any one of the side surfaces 13a, 13b, 13c, and 13d can be the second surface. The side surface 13a and the side surface 13b are arranged in the X-axis direction and facing away from each other. The side surface 13c and the side surface 13d are arranged in the Y-axis direction and facing away from each other. The bottom surface 11, the top surface 12, and the side surfaces 13a, 13b, 13c, and 13d are respectively substantially flat planes. The group of the bottom surface 11 and the top surface 12, the group of the side surface 13a and the side surface 13b, and the group of the side surface 13c and the side surface 13d are groups of surfaces that are in a parallel positional relationship. The bottom surface 11 and the top surface 12 extend in a direction intersecting with the side surfaces 13a, 13b, 13c, and 13d, specifically, in a direction orthogonal to them. In addition, the side surfaces 13a and 13b extend in a direction intersecting with the side surfaces 13c and 13d, specifically, in a direction orthogonal to them.

[0040] The coil element 20 has: a coil portion 21, which is composed of a wire embedded in the magnetic core 10 and is a portion around which the wire is wound; a plurality of ends, corresponding to the two ends of the wire, exposed to the outside of the magnetic core 10; and a lead portion, which connects each end to the coil portion 21. That is, the coil element 20 of the embodiment is composed of a coil portion 21, two lead portions, and two ends. Figure 1 In FIG. 1 , the embedded coil portion 21 and the lead portion are indicated by dotted lines.

[0041] The coil element 20 is composed of, for example, a conductive wire. The conductive wire is composed of a metal wire and an insulating coating covering the surface of the metal wire, and the metal wire is composed of a metal material selected from metals such as aluminum, copper, silver, and gold, alloys containing one or more of these metals, and materials composed of metals or alloys and other substances. Specifically, the conductive wire is, for example, a copper wire covered with an insulating coating. The coil portion 21, the lead portion, and the end portion are names given to various parts formed by, for example, processing a component composed of the same material.

[0042] The coil portion 21 is a part of the buried portion 24 covered by the magnetic core 10. The coil portion 21 is formed by winding a conductive wire and functions as a coil. The number of turns of the coil portion 21 is not particularly limited. For example, in order to adapt to the performance required of the inductor 100 and the size of the magnetic core 10, 0.5 turns to 10 turns are appropriately selected. The cross-section of the conductive wire constituting the coil portion 21 is, for example, a flat wire with each side of 6.0 mm×3.5 mm. In addition, the coil portion 21 can also be composed of a square wire with an aspect ratio of 1:1 in the cross-section. In addition, the coil portion 21 is wound in the longitudinal direction by overlapping the surface of the conductive wire including the long side of the cross-section. That is, the coil portion 21 is formed by winding the flat wire along the side. The coil portion 21 is buried in the magnetic core 10 in such a way that the winding axis B (the double-dashed line in the figure) of the coil portion 21 is along the direction connecting the bottom surface 11 and the top surface 12 (Z-axis direction).

[0043] The coil portion 21 has a first lead portion 22 and a second lead portion 23 connected to the side surface 13c of the magnetic core 10 from the wound portion. In the following, when the first lead portion 22 and the second lead portion 23 are not particularly distinguished, they are sometimes collectively described as a lead portion. In the lead portion, when viewed from a direction perpendicular to the side surface 13c, the second lead portion 23 is arranged on the right outer side, that is, the positive side of the X axis, relative to the winding axis B, and the first lead portion 22 is arranged on the left outer side, that is, the negative side of the X axis relative to the winding axis B. In addition, when viewed from a direction perpendicular to the side surface 13c, the second lead portion 23 is located at a height closer to the bottom surface 11 side than the center of the side surface 13c. On the other hand, when viewed from a direction perpendicular to the side surface 13c, the first lead portion 22 extends in a direction connecting the bottom surface 11 and the top surface 12 in a manner that reaches the same height as the second lead portion 23 from the height closer to the top surface 12 side than the center of the side surface 13c. On the side surface 13c, the height of the lead portion from the bottom surface 11 is the same height. In other words, on the side surface 13 c , the distances of the lead portions from the bottom surface 11 are all the same.

[0044] The end is connected to the coil portion 21 via the lead portion. The end includes a first end 25 and a second end 26. The first end 25 is connected to the coil portion 21 via the first lead portion 22. The second end 26 is connected to the coil portion 21 via the second lead portion 23. In the following, when the first end 25 and the second end 26 are not particularly distinguished, they are sometimes collectively recorded as ends. The end is led outward from the side 13c of the magnetic core 10 and extends. Specifically, the end is led out in a direction perpendicular to the side 13c from the height of the side 13c closer to the bottom surface 11 than the center. The end is led out from one of the four side surfaces 13a to 13d. In other words, on the same side of the four side surfaces 13a to 13d, the two ends protrude to the outside of the magnetic core 10.

[0045] exist Figure 2 In the figure, the structure on the opposite side of the viewpoint is visible through the dotted line. Figure 2 As shown, in the first lead-out portion 22, a curved portion 31 is formed in the extension direction of the wire between a section extending in a direction away from the coil portion 21 and a section extending along the winding axis B of the coil portion 21 or in a direction connecting the bottom surface 11 and the top surface 12. Similarly, in the first lead-out portion 22, a curved portion 31 is formed in the extension direction of the wire between a section extending along the winding axis B of the coil portion 21 and a section extending in a direction away from the coil portion 21 at a height parallel to the extension height of the second lead-out portion 23.

[0046] By forming the bent portion 31, a notch 32 is formed in the flat wire as the wire material, and the notch 32 extends in a direction orthogonal to the directions extending in front and behind the bent portion 31. The notch 32 can also be interpreted as a fold formed on the inner side of the bend. In addition, in the present embodiment, the inductor 100 in which the first lead portion 22 has two bent portions 31 is described, but there may be more than three bent portions 31. In addition, the second lead portion may also have a plurality of bent portions. Moreover, in the present embodiment, the inductor 100 in which the lead portions on the side 13c are all located at a height closer to the bottom surface 11 than the center of the side 13c is described, but the lead portions on the side 13c may all be at the same height, and may be located in the middle of the height of the side 13c, or may be closer to the top surface 12 than the center of the side 13c.

[0047] In the present embodiment, the structure of the bend 31 of the two bends 31 which is closest to the coil portion 21 in the wire, in other words, the bend 31 in which the straight-line distance between the indentation 32 and the coil portion 21 is closest, is different from the structure of the other bends 31. Specifically, in the bend 31 closest to the coil portion 21, a notch structure 33 (the dotted shaded area in the figure) is formed at the position of the notch 32, in which the surface of the wire is sunken inward. The notch structure 33 is a surface extending deeply within a plane intersecting the surface of the wire, and is filled with the space that existed before the wire was bent by bending. Therefore, a cut 33a for forming the notch structure 33 is formed in the wire before the original bending (refer to the part described later). Figure 6 ). Regarding the cutout 33a, Figure 6 The description of will be described later.

[0048] Due to the presence of the cutout 33a, when the wire is bent, the expanded portion of the metal material from the surface of the wire formed by the contraction of the metal material on the inner side of the bend closer to the neutral line can enter the space of the cutout 33a, so that the expanded portion can be kept relatively small. As a result, in the bent portion 31 of the first lead-out portion 22, the expanded portion toward the coil portion 21 is not easy to expand, and the distance between the coil portion 21 and the expanded portion of the first lead-out portion 22 is easy to maintain.

[0049] use Figure 3 To be more specific. Figure 3 This is a third perspective view of the inductor according to the embodiment. Figure 3 It is from Figure 2 A three-dimensional view of the vicinity of the curved portion 31 closest to the coil portion 21 as viewed from different viewpoints. Figure 3 In (a), only the general shape of the expansion portion 34 is shown by the dotted line diagram, and the perspective notch structure 33 is also shown by the dotted line diagram. Figure 3 In (b) , the expansion portion 34 is shown completely without perspective.

[0050] like Figure 3 As shown, at each position in the extension direction of the notch 32, the depth of the notch structure 33 sinking into the wire is different. The sinking depth of the notch structure corresponds to the size of the space of the cutout 33a before bending. The wider the space, the deeper the sinking depth. Figure 3 As shown in (a), the depth of the indentation is deepest at one end side of the indentation 32 which is closer to the straight-line distance to the coil portion 21, or at one end side of the indentation 32 which is closer to the straight-line distance to the winding axis B of the coil portion 21 (the positive side of the X-axis), and is shallowest at the other end side (the negative side of the X-axis).

[0051] In this way, Figure 3As shown by the double arrows in (b), it is possible to take into account both the expansion of the bulge portion 34 on the side closer to the straight-line distance between the coil portion 21, which has a greater risk of reducing insulation, and the reduction of the cross-sectional area of ​​the notch structure 33, that is, the increase in resistance. In addition, the notch structure 33 may also be sunk to a depth of 0 between one end and the other end of the notch 32. That is, the space of the notch 33a may also be formed only in a part of the direction in which the notch 32 extends.

[0052] [Inductor Manufacturing Method]

[0053] Next, a method for manufacturing the above-mentioned inductor 100 will be described. The inductor of the embodiment is manufactured as follows. The method for manufacturing the inductor 100 is not limited to the following example. Figure 4 : is a flowchart showing a method for manufacturing an inductor according to an embodiment. Figure 5 This is a flowchart showing a method for forming a coil element of an inductor according to an embodiment.

[0054] In the method for manufacturing the inductor 100, a step of forming a coil element is first performed (S101). Figure 5 The process is divided into three steps as shown. Specifically, first, a portion between the two ends of the wire is wound to form the coil portion 21 (S201). After the formation of the coil portion 21 or before the winding of the final turn of the coil portion 21 is completed, a cutout 33a is formed at a position corresponding to the indentation 32 during bending (S202). Regarding the formation of the cutout 33a, a mold with a protrusion bar having the same shape as the space of the cutout 33a is used for pressing, so that the metal material corresponding to the space of the cutout 33a is pressed into the interior of the wire to form the space of the cutout 33a. In addition, the formation of the cutout 33a can also be performed by other methods such as cutting. After the cutout 33a is formed, it is bent along the cutout 33a to form the bent portion 31, and the notch structure 33 is formed (S203). If this time point is in the process of performing step S101, the winding of the final turn of the coil portion 21 is further completed.

[0055] Here, refer to Figure 6 The shape of the cutout 33a will be described. Figure 6 1 is a plan view for explaining the shape of the cutout in the embodiment. Figure 6 In the figure, (a) is a plan view of the lead portion 22a corresponding to the first lead portion 22 before bending, observed from the extension direction of the wire, (b) is a plan view of the lead portion 22a observed from a direction orthogonal to the extension direction of the wire and the extension direction of the cut 33a (corresponding to the extension direction of the indentation 32), and (c) is a plan view of the lead portion 22a observed from the extension direction of the cut 33a.

[0056] exist Figure 6 In (a), the cutout 33a is shown by a dotted line. Figure 6 As shown, the cutout 33a absorbs the expansion of the expanded portion 34 during bending according to the size of the space. Therefore, the cutout 33a is formed so that a larger space is provided at one end side which is closest to the coil portion 21 in a straight line and needs to further absorb the expansion of the expanded portion 34, and a smaller space is provided at the other end side in order to suppress the reduction of the cross-sectional area caused by the formation of the notch structure 33.

[0057] For this purpose, the notch 33a has a deeper sinking depth at one end closest to the coil portion 21 and a shallower sinking depth at the other end. For example, the deepest sinking depth of the notch 33a ( Figure 6 h1) in (c) can be the length of the flat wire in the sinking direction ( Figure 6 10% or more of h2) in (c), or more than 20%. Thus, the expansion of the expanded portion 34 can be effectively absorbed by the space of the cutout 33a. The deepest penetration depth of the notch structure 33 can also be more than 10% of the length of the flat wire in the penetration direction, or more than 20%. However, strictly speaking, the penetration depth of the notch structure and the penetration depth of the notch 33a are inconsistent due to the expansion and contraction of the metal material, so the penetration depth can be set for either the notch 33a or the notch structure 33. In addition, strictly speaking, after bending, since the thickness outside the neutral plane becomes thinner, the proportion of the penetration depth of the notch structure 33 in the thickness tends to increase compared to before bending.

[0058] In addition, the deepest sinking depth h1 of the notch 33a may be less than 50% of the length h2 of the flat wire in the sinking direction, or less than 40%. This can prevent the cross-sectional area from being unnecessarily reduced due to the formation of the notch structure 33. The deepest sinking depth of the notch structure 33 may also be less than 50% of the length of the flat wire in the sinking direction, or less than 40%. However, strictly speaking, the sinking depth of the notch structure 33 and the sinking depth of the notch 33a are different due to the expansion and contraction of the metal material, so the sinking depth can be set for either the notch 33a or the notch structure 33.

[0059] More preferably, the notch structure 33 and the cutout 33a are formed from the inner side of the bent portion 31 obtained by bending the flat wire (the side where the metal material contracts) to the neutral plane. To this end, the sinking depth can be determined by conducting an experiment for estimating the neutral line of the flat wire in advance.

[0060] In addition, if Figure 6As shown, at both ends of the direction in which the cutout 33a extends, the width of the cutout 33a in the direction orthogonal to the direction in which the cutout 33a extends is different. Specifically, the width w1 of the other end side of the cutout 33a, which is farther from the winding axis B in a straight line, is shorter than the width w2 of the one end side of the cutout 33a, which is closer to the winding axis B in a straight line. In other words, the width w2 of the one end side of the cutout 33a is longer than the width w1 of the other end side of the cutout 33a. According to the structure in which the width of the cutout 33a changes along the direction in which the cutout 33a extends, it is easy to design a larger space at one end side of the cutout 33a than at the other end side. Specifically, in combination with the above description of the sinking depth, at one end side of the cutout 33a, the width w2 is longer than that at the other end side, and the sinking depth is deeper than that at the other end side, thereby forming a larger space than at the other end side. On the other hand, at the other end side of the cutout 33 a , the width w1 is shorter than that at the one end side, and the sunken depth is shallower than that at the one end side, so that a smaller space than that at the one end side is formed.

[0061] return Figure 4 The formed coil element 20 is placed in a forming mold together with a mixture of magnetic material powder and a binder, and the powder core is pressed and formed, thereby burying the coil element 20 in the magnetic core 10 (S102). The pressure during the press forming is, for example, 5 ton / cm 2 The heat curing temperature is, for example, 185° C. After the press forming, the exposed end portion not covered by the core 10 protrudes vertically relative to the side surface 13 c of the core 10 . The end portion is irradiated with a laser beam, for example, to remove the insulating coating. In this way, the inductor 100 is manufactured.

[0062] [Effects, etc.]

[0063] First embodiment: As described above, the inductor 100 of the present embodiment includes: a magnetic core 10 obtained by press-molding a mixture of magnetic material powder and a binder, and having a bottom surface 11 (first surface) and a side surface 13c (second surface) connected to the bottom surface 11; and a coil element 20, including an embedded portion 24 embedded in the magnetic core 10 and two end portions respectively connected to the embedded portion 24, the two end portions protruding to the outside of the magnetic core 10 at positions at the same height from the bottom surface 11, the coil element 20 being composed of a rectangular wire having an insulating coating on the surface and having a rectangular cross-sectional shape, the embedded portion 24 of the coil element 20 having a coil portion 21 wound with the rectangular wire, and a side surface 13c (second surface) connected to the coil portion 21 and one of the two end portions (the first end portion 24). 5), and a second lead-out portion 23 connected to the coil portion 21 and the other of the two ends (the second end 26), wherein the first lead-out portion 22 is provided with two or more bent portions 31 bent in the extension direction of the flat wire, and the two or more bent portions 31 have an indentation 32 on the surface of the flat wire in each of the two or more bent portions 31, and a notch structure 33 is formed in the bend 31 closest to the coil portion 21 among the two or more bent portions 31, and the notch structure 33 is sunken in the indentation 32 toward the inside of the flat wire, and the sunken depth of one end side of the indentation 32 which is closer to the straight-line distance from the winding axis B of the coil portion 21 is deeper than the sunken depth of the other end side of the indentation 32 which is farther from the straight-line distance from the winding axis.

[0064] Thus, by forming the curved portion 31, the bulge 34 formed on the concave fold side of the curve can be absorbed when the notch structure 33 is formed. Since the depth of the notch structure 33 corresponds to the volume of the bulge 34 that can be absorbed during its formation, the bulge 34 is less likely to be formed on one end side of the notch 32 than on the other end side of the notch 32, that is, the formed bulge 34 can be further reduced. As a result, on the one end side of the notch 32, the reduction in insulation between the coil portion 21 is suppressed, and the inductor 100 with high reliability can be realized.

[0065] Second embodiment: In addition, for example, in the inductor 100 described in the first embodiment, the core 10 further has other side surfaces 13a, 13b, 13d (third surface) connected to the bottom surface 11, and both end portions protrude to the outside of the core 10 at the side surface 13c.

[0066] This makes it possible to realize the inductor 100 in which both end portions protrude from the side surface 13 c. When the inductor 100 is incorporated into an electronic circuit, it is easy to handle and has an advantage in terms of easy connection.

[0067] Third aspect: For example, in the inductor 100 according to the first aspect or the second aspect, the deepest depression depth of the notch structure 33 may be 10% or more of the length of the rectangular wire in the depression direction.

[0068] Thereby, it is possible to realize the inductor 100 formed with the notch structure 33 having the recessed depth required for further reducing the swollen portion 34 .

[0069] Fourth aspect: For example, in the inductor 100 according to any one of the first to third aspects, the deepest depression depth of the notch structure 33 may be equal to or less than 50% of the length of the rectangular wire in the depression direction.

[0070] Thus, even if the cross-sectional area of ​​the rectangular wire is reduced by the notch structure 33 , the cross-sectional area of ​​the rectangular wire can be maintained at a certain value or more, and the inductor 100 having the notch structure 33 while suppressing an increase in resistance can be realized.

[0071] Fifth mode: In addition, for example, the manufacturing method of the inductor 100 of the present embodiment includes: a step of forming the coil element 20, which is a step of forming the coil element 20 composed of a rectangular wire having an insulating coating on the surface and having a rectangular cross-sectional shape, including: forming a coil portion 21 formed by winding a portion between two ends of the rectangular wire; and bending a first lead portion 22 connecting one end (first end 25) of the two ends and the coil portion 21 two or more times to form two or more bent portions 31 having indentations 32 on the surface of the rectangular wire; and forming the magnetic core 10 by press-molding a mixture of magnetic material powder and a binder, thereby A process of burying the coil portion 21 and the first lead portion 22 of the coil element 20 in the magnetic core 10; in the formation of two or more bent portions 31, after forming a cut 33a on the surface of the flat wire that is sunken toward the inside of the flat wire at a position corresponding to the indentation 32 in the bent portion 31 closest to the coil portion 21 among the two or more bent portions 31, the flat wire is bent to form a notch structure 33 that is sunken toward the inside of the flat wire in the indentation 32, and the depth of sunkenness of one end side of the notch structure 33 that is closer to the winding axis B of the coil portion 21 is deeper than the depth of sunkenness of the other end side of the notch 32 that is farther from the winding axis.

[0072] Sixth embodiment: In addition, for example, it may be a method for manufacturing the inductor 100 as described in the fifth embodiment, wherein the width of the cut 33a in a direction perpendicular to the direction in which the indentation 32 extends is longer at one end of the indentation 32 which is closer to the winding axis B in a straight line than at the other end of the indentation 32 which is farther from the winding axis B in a straight line.

[0073] According to these aspects, the inductor 100 described in the first aspect and the like can be manufactured.

[0074] (Other Implementations, etc.)

[0075] The above describes the inductors and the like of the embodiments and variants of the present disclosure, but the present disclosure is not limited to the above embodiments and variants. As long as it does not deviate from the main purpose of the present disclosure, the embodiments and variants are implemented in various ways that can be thought of by those skilled in the art, and other ways constructed by combining some structural elements in the embodiments and variants are also included in the scope of the present disclosure.

[0076] For example, in the above embodiment, an example is shown in which the end portion is led out from the height of the side surface 13c closer to the bottom surface 11 than the center, but the end portion is not limited to this. The lead portion may also be led out from the height of the side surface 13c closer to the top surface 12 than the center. In this case, the same bent portion 31 may be formed in the second lead portion 23.

[0077] Furthermore, for example, terminal metal fittings (not shown) may be connected to the ends of the first end portion 25 and the second end portion 26 by welding, or the ends of the first end portion 25 and the second end portion 26 may be bent to serve as electrodes for surface mounting.

[0078] In addition, for example, an electric product or electric circuit using the above-mentioned inductor is also included in the present disclosure. As the electric product, there can be mentioned a power supply device including the above-mentioned inductor, various devices including the power supply device, and the like.

[0079] Industrial Applicability

[0080] The inductor of the present disclosure is useful as an inductor used in various devices and equipment.

[0081] Description of Reference Numerals

[0082] 10 cores

[0083] 11 Bottom surface (first surface)

[0084] 12 Top surface

[0085] 13a, 13b, 13c, 13d side

[0086] 20 coil elements

[0087] 21 Coil unit

[0088] 22 first lead-out portion

[0089] 22a Lead-out section

[0090] 23 Second lead-out portion

[0091] 24 buried part

[0092] 25 first end

[0093] 26 Second end

[0094] 31 bending part

[0095] 32 Dents

[0096] 33 notch structure

[0097] 33a incision

[0098] 34 expansion part

[0099] 100 Inductor

Claims

1. An inductor, characterized in that: have: a magnetic core obtained by press-molding a mixture of magnetic material powder and a binder, and having a first surface and a second surface connected to the first surface; and a coil element having an embedded portion embedded in the magnetic core and two ends respectively connected to the embedded portion, the two ends protruding to the outside of the magnetic core at positions at the same height from the first surface, the coil element being composed of a flat wire having a rectangular cross-sectional shape and having an insulating coating on the surface, The embedded portion of the coil element has a coil portion wound with the rectangular wire, a first lead portion connected to the coil portion and one of the two ends, and a second lead portion connected to the coil portion and the other of the two ends. The first lead portion is provided with two or more bent portions bent in the extending direction of the rectangular wire, and the two or more bent portions have a dent on the surface of the rectangular wire in each bent portion. A notch structure is formed at a bend portion closest to the coil portion among the two or more bend portions, and the notch structure is sunken into the inside of the flat wire in the notch. The notch structure has a recessed depth at one end of the notch closer to the winding axis of the coil portion than at the other end of the notch farther from the winding axis.

2. The inductor according to claim 1, characterized in that The magnetic core also has another third surface connected to the first surface, The two end portions protrude to the outside of the magnetic core at the second surface.

3. The inductor according to claim 1, wherein: The deepest sinking depth of the notch structure is more than 10% of the length of the flat wire in the sinking direction.

4. The inductor according to any one of claims 1 to 3, wherein: The deepest sinking depth of the notch structure is less than 50% of the length of the flat wire in the sinking direction.

5. A method for manufacturing an inductor, characterized in that: Including the following processes: The process of forming a coil element is a process of forming a coil element composed of a rectangular wire having an insulating coating on the surface and having a rectangular cross-sectional shape, comprising the following steps: forming a coil portion formed by winding a portion between two ends of the rectangular wire; and bending a first lead portion connecting one of the two ends and the coil portion twice or more to form two or more bent portions having indentations on the surface of the rectangular wire; and a step of forming a magnetic core by press-molding a mixture of magnetic material powder and a binder, and embedding the coil portion and the first lead portion of the coil element in the magnetic core; In forming the two or more bent portions, after forming a notch that sinks into the surface of the flat wire toward the inside of the flat wire at a position corresponding to the notch in the bent portion closest to the coil portion among the two or more bent portions, the flat wire is bent to form a notch structure that sinks into the inside of the flat wire in the notch, The notch structure has a recessed depth at one end of the notch closer to the winding axis of the coil portion than at the other end of the notch farther from the winding axis.

6. The method for manufacturing an inductor according to claim 5, wherein: The width of the cutout in a direction perpendicular to the direction in which the notch extends is longer at one end of the notch closer to the winding axis than at the other end of the notch farther from the winding axis.

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