Inductor and method for manufacturing inductor

Abstract

The present invention suppresses deterioration of reliability of an inductor. This inductor is provided with a magnetic core, a coil element embedded in the magnetic core, and an electrode member connected to the coil element. The coil element has a winding portion in which a conductive wire with an insulating film is wound, and a lead portion (23) led out from an end of the winding portion. The electrode member includes: a side plate portion; a first lead-out portion (31) extending from the side plate portion into the magnetic core; and a connection portion (34) including a second crimping portion (34b) and a first crimping portion (34a). In the connection portion (34), the lead portion (23) is sandwiched between and crimped by the second crimping portion (34b) and the first crimping portion (34a) inside the magnetic core. The connection portion (34) includes a welded portion (34m) in which the connection portion (34) between a first melting mark (34 ma) and a second melting mark (34 mb), and the lead portion (23) are melted and solidified.

Description

Inductor and method for manufacturing the same

[0001] The present disclosure relates to inductors and methods for manufacturing inductors.

[0002] In recent years, as electronic devices have become more sophisticated, there has been a demand for smaller size and a tendency for the current used to increase, and there is a demand for inductors that can satisfy both of these requirements.

[0003] One example of such a conventional inductor is an inductor in which a coil is covered with magnetic powder and the magnetic powder is pressure-molded to form a magnetic core. Patent Document 1 proposes an electronic component (inductor) in which a pair of terminals of a winding portion made of a conductive wire of a coil component are fixed by crimping to crimping holding portions of a terminal plate material and fixed by resistance welding, and the portions to which the terminals and crimping holding portions are resistance-welded are placed inside the magnetic core.

[0004] Japanese Patent Application Laid-Open No. 2020-43370

[0005] However, in the inductor disclosed in Patent Document 1, when the conductive wire material of the coil component and the terminal plate material are made of a high-purity copper material such as tough-pitch copper, copper does not generate heat easily due to its low specific resistance and is prone to heat loss due to its high thermal conductivity, making it difficult to obtain a nugget (welded joint) even with resistance welding and prone to becoming a diffusion-bonded joint. If this diffusion-bonded joint is covered with magnetic powder and then pressure-molded, there is a risk that the joint will come off due to insufficient strength.

[0006] For this reason, in order to increase the connection strength, it is conceivable to use a method such as laser welding to melt the crimped portion of the conductor and terminal plate material with a large amount of heat to form a molten ball. However, in small inductors, the distance between the joint and the insulating coating of the coil winding and coil lead portions is short, so the heat from welding can deteriorate the insulating coating of the conductor; specifically, the insulating coating can foam and become cloudy, causing problems with the reliability of the inductor.

[0007] In view of the above problems, the present disclosure provides an inductor and a method for manufacturing an inductor that can prevent a decrease in the reliability of the inductor.

[0008] An inductor according to one aspect of the present disclosure includes a magnetic core having a bottom surface, a top surface facing away from the bottom surface, and an end surface connecting the bottom surface and the top surface, a coil element embedded in the magnetic core, and an electrode member connected to the coil element. The coil element has a winding portion around which an insulating-coated conductor wire is wound and a lead portion extending from an end of the winding portion. The electrode member has a side plate portion arranged along the end surface, a first lead portion extending from the end of the side plate on the top surface side into the magnetic core, and a connection portion connected to the first lead portion and including, in order from closest to the first lead portion, a second crimping portion and a first crimping portion. The connection portion is crimped inside the magnetic core, sandwiching the lead portion between the second crimping portion and the first crimping portion. The connection portion has a first melting mark which is a melting mark formed on the surface of the first crimping portion where the first crimping portion has melted and solidified, a second melting mark which is a melting mark formed on the surface of the second crimping portion where the second crimping portion has melted and solidified, and a welded portion between the first melting mark and the second melting mark where the connection portion and the lead portion have melted and solidified.

[0009] A method for manufacturing an inductor according to another aspect of the present disclosure is a method for manufacturing an inductor including a coil element embedded in a magnetic core and an electrode member connected to the coil element, and includes a coil element forming process, an electrode member preforming process, a connection process, and a magnetic core forming process. The coil element forming process forms a coil element having a winding portion and a lead portion extending from an end of the winding portion. The electrode member preforming process includes the coil element forming process and forming an electrode member having a side plate portion arranged along a predetermined direction, a first lead portion bent at one end of the side plate portion in the predetermined direction, and a connection portion extending from the first lead portion and including a second crimping portion and a first crimping portion in that order from closest to the first lead portion. The connection process connects the lead portion and the connection portion. The magnetic core forming process embeds the coil element, the first lead portion, and the connection portion in the magnetic core. The connection process fusion-connects the connection portion and the lead portion using the following procedure. That is, the lead portion is sandwiched and crimped between the second crimping portion and the first crimping portion. Then, laser light is irradiated onto the surface of the first crimping portion in a direction from the surface side of the first crimping portion toward the surface of the second crimping portion, to form a first melting mark on the surface of the first crimping portion, which is a melting mark where the first crimping portion melts and solidifies, and to form a second melting mark on the surface of the second crimping portion, which is a melting mark where the second crimping portion melts and solidifies, and the connection portion between the first melting mark and the second melting mark and the lead portion are melt-connected.

[0010] According to the inductor and the method for manufacturing the inductor of the present disclosure, it is possible to prevent the reliability of the inductor from decreasing.

[0011] FIG. 1 is a schematic diagram showing an inductor according to an embodiment. FIG. 2 is a diagram showing a scene in which a coil element and an electrode member are connected in the embodiment. FIG. 3 is a diagram showing the lead portion of the coil element and the electrode member from the end face side of the magnetic core in a scene in which the coil element and the electrode member of FIG. 2 are connected. FIG. 4 is an external view of an inductor according to an embodiment. FIG. 5 is an external view of an inductor according to an embodiment. FIG. 6 is a diagram showing a coil element and an electrode member of an inductor according to an embodiment. FIG. 7 is a diagram showing a coil element and an electrode member of an inductor according to an embodiment. FIG. 8 is a diagram showing a coil element and an electrode member of an inductor according to an embodiment. FIG. 9 is a diagram showing a connection portion of an inductor according to an embodiment. FIG. 10 is a diagram comparing DCR characteristics of an inductor according to an embodiment with a comparative example. FIG. 11 is a diagram comparing the coating foaming distance of an inductor according to an embodiment with a comparative example. FIG. 12 is a diagram showing the relationship between the bottom melting area and the ratio of the total melting area / conductor cross-sectional area of ​​an inductor according to an embodiment. FIG. 13 is a diagram comparing DCR characteristics of an inductor according to an embodiment with a comparative example. FIG. 14 is a diagram comparing DCR characteristics of an inductor according to an embodiment with a comparative example. FIG. 1 is a diagram showing a coil element formed by a coil element forming step; FIG. 2 is a diagram showing an electrode member formed by an electrode member pre-forming step; FIG. 3 is a diagram showing an example of a connecting step for connecting a coil element and an electrode member; FIG. 4 is a diagram for explaining welding marks on an inductor according to a modified example of an embodiment; FIG. 5 is a diagram for explaining welding marks on an inductor according to a modified example of an embodiment; FIG. 6 is a diagram for explaining welding marks on an inductor according to a modified example of an embodiment; FIG. 7 is a diagram for explaining welding marks on an inductor according to a modified example of an embodiment;

[0012] (Embodiments) [Configuration of Inductor] Hereinafter, embodiments will be specifically described with reference to the drawings. Note that each of the embodiments described below represents a specific example of the present disclosure. The numerical values, shapes, materials, components, component placement positions, connection configurations, steps, and step order 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 will be described as optional components.

[0013] 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.

[0014] Furthermore, each figure 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 figure, the same reference numerals are used to designate components that are substantially the same as those in other figures, and duplicated explanations may be omitted or simplified.

[0015] 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.

[0016] Furthermore, in this specification, the terms "top surface" and "bottom surface" in the configuration of an inductor do not refer to the top surface (the surface on the vertically upper side) and 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 components of the inductor.

[0017] [Configuration of Inductor] FIG. 1 is a diagram showing an inductor 1 according to an embodiment.

[0018] The inductor 1 according to the embodiment is a passive element that stores electrical energy flowing through a coil element as magnetic energy.

[0019] The inductor 1 of the embodiment includes a magnetic core 10, a coil element 20 having a winding portion 21 and multiple lead portions 23, 24, and multiple electrode members 30 and 40 that serve as terminal electrodes. Note that the magnetic core 10 is indicated by a dashed line in Fig. 1. The magnetic core 10 is rectangular parallelepiped-shaped and has a bottom surface 18, a top surface 19, end surfaces 13 and 14, and side surfaces 15 and 16.

[0020] One lead portion 23 of the coil element 20 is fixed by crimping to the connection portion 34 of the electrode member 30, and the other lead portion 24 is fixed by crimping to the connection portion 44 of the electrode member 40. Then, one lead portion 23 of the coil element 20 is fusion-connected to the connection portion 34, and the other lead portion 24 is fusion-connected to the connection portion 44. In this fusion connection, first fusion marks 34ma and 44ma are formed on the connection portions 34 and 44, respectively. The fusion connection between the lead portions 23 and 24 and the connection portions 34 and 44 will be described later. Protrusions 33 and 43 are formed on the electrode members 30 and 40, respectively. In the height direction (Z-axis direction), the protrusions 33 and 43 protrude more than the first lead portions 31 and 41. When connecting the electrode members 30, 40 and the coil element 20, one lead portion 23 of the coil element 20 is crimped and fixed to the connection portion 34 of the electrode member 30, and the other lead portion 24 is crimped and fixed to the connection portion 44 of the electrode member 40. In order to bring the lead portions 23, 24 into contact with the connection portions 34, 44 before crimping and fixing the lead portions 23, 24 to the connection portions 34, 44, respectively, the coil element 20 is positioned so that the lead portions 23, 24 are located on the protrusions 33, 43 of the electrode members 30, 40, respectively. Then, by rotating the coil element 20 around the winding axis 21c of the winding portion 21 (see FIG. 2 described later), the lead portions 23, 24 are rotated and brought into contact with the connection portions 34, 44, respectively. In this embodiment, the first lead portions 31 and 41 are formed by bending the electrode members 30 and 40, respectively, and the first grooves 36 and 46 are formed to facilitate this bending. If the protrusions 33 and 43 were not formed, notches corresponding to the depths of the first grooves 36 and 46 would be formed, respectively, and these notches for bending the first lead portions 31 and 41 would be lower in the height direction than the first lead portions 31 and 41 after bending. When the coil element 20 is rotated as described above to bring the lead portions 23 and 24 into contact with the connection portions 34 and 44, respectively, the presence of such low notches would likely cause problems, such as the lead portions 23 and 24 getting caught in the notches. Therefore, in this embodiment, the protrusions 33 and 43 are provided so as to protrude higher in the height direction than the first lead portions 31 and 41, respectively.This is explained in more detail below.

[0021] Fig. 2 is a diagram showing a state in which the coil element 20 and the electrode members 30, 40 are connected in the embodiment. Fig. 3 is a diagram showing the lead portion 23 of the coil element 20 and the electrode member 30 as viewed from the end face 13 side of the magnetic core 10 in a state in which the coil element 20 and the electrode members 30, 40 are connected in Fig. 2. Figs. 2 and 3 show a state before the connection portion 34 is fixed to the lead portion 23 by crimping.

[0022] In the inductor 1 of the embodiment, first, the coil element 20 is positioned so that the lead portion 23 is located on the protruding portion 33 of the electrode member 30. Then, by rotating the coil element 20 around the winding axis 21c of the winding portion 21, the lead portion 23 is rotated and positioned at the connection portion 34. In the embodiment, the lead portion 23 is positioned on the protruding portion 33, which is higher than the first lead portion 31. Therefore, when the lead portion 23 is rotated, the lead portion 23 moves smoothly over the protruding portion 33 and the first lead portion 31 and is positioned at the connection portion 34. This prevents the lead portion 23 from being damaged and reduces the reliability of the inductor 1. Furthermore, since the lead portion 23 can be prevented from getting caught on the electrode member 30, a reduction in production efficiency can be suppressed.

[0023] 4A and 4B are external views of the inductor 1 according to the embodiment. Figures 5A and 5B are diagrams showing the coil element 20 and electrode members 30 and 40 of the inductor 1 according to the embodiment.

[0024] Figures 4A and 4B are perspective views of the inductor 1 viewed from different angles. Figures 5A and 5B are perspective views of the coil element 20 and the electrode members 30 and 40 viewed from different angles. In Figures 5A and 5B, the outline of the magnetic core 10 is shown by a dashed line.

[0025] Figures 6 and 7 are diagrams showing the coil element 20 and electrode members 30, 40 of the inductor 1 according to the embodiment. The magnetic core 10 is not shown in Figures 6 and 7. Figure 8 is a diagram showing the connection portion 34 of the inductor 1 according to the embodiment. Figures 8(a) and 8(b) are cross-sectional views taken along lines VIIIA-VIIIA and VIIIB-VIIIB shown in Figure 6, respectively, focusing on the vicinity of the connection portion 34.

[0026] 4A, 4B, 5A, and 5B includes a magnetic core 10, a coil element 20 having a winding portion 21 and multiple lead portions 23 and 24, and multiple electrode members 30 and 40 that are terminal electrodes. The approximate outer shape of the inductor 1 is determined by the shape of the magnetic core 10, which is, for example, a powder magnetic core. The magnetic core 10 is molded into any shape by molding. In other words, the shape of the magnetic core 10 during molding determines the shape of the inductor 1. The magnetic core 10 of this embodiment is rectangular and has, for example, dimensions of 10 mm in the X-axis direction, 10 mm in the Y-axis direction, and 5 mm in the Z-axis direction.

[0027] The magnetic core 10 is the outer shell of the inductor 1 and covers the entire coil element 20 and portions of the electrode members 30 and 40. The magnetic core 10 is a powder magnetic core made of a magnetic material, such as a mixture of a metal magnetic powder and a resin material. The magnetic core 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 resin material is selected from materials such as silicone resins that can maintain a certain shape by binding the metal magnetic powder particles while insulating them from each other.

[0028] The magnetic core 10 has a bottom surface 18, a top surface 19 facing away from the bottom surface 18, and two end surfaces 13 and 14 connecting the bottom surface 18 and the top surface 19. The magnetic core 10 also has two side surfaces 15 and 16 connecting the bottom surface 18 and the top surface 19 and joining the end surfaces 13 and 14. The magnetic core 10 has a quadrangular shape when viewed from a direction perpendicular to the top surface 19 (the Z-axis direction). The magnetic core 10 may also have a rectangular or square shape when viewed from a direction perpendicular to the top surface 19. The bottom surface 18 and the top surface 19 face each other back to back in the Z-axis direction, the end surfaces 13 and 14 face each other back to back in the Y-axis direction, and the side surfaces 15 and 16 face each other back to back in the X-axis direction.

[0029] The bottom surface 18, top surface 19, end surfaces 13, 14, and side surfaces 15, 16 each have a flat surface. The bottom surface 18 and top surface 19 are aligned in the Z-axis direction and parallel to each other. The end surfaces 13 and 14 are aligned in the Y-axis direction. The side surfaces 15 and 16 are aligned in the X-axis direction and parallel to each other. In this example, the end surfaces 13 and 14 are inclined inward, and the distance between them decreases from the bottom surface 18 to the top surface 19.

[0030] Furthermore, the bottom surface 18, the top surface 19, and the end surface 13 (or 14) intersect with each other when the plane is extended. The bottom surface 18, the top surface 19, and the side surface 15 (or 16) intersect with each other when the plane is extended, specifically, they are perpendicular to each other. The end surface 13 (or 14) and the side surface 15 (or 16) intersect with each other when the plane is extended.

[0031] Two bottom surface recesses 18a are formed on the bottom surface 18 of the magnetic core 10 (see FIG. 1). The bottom plate portion 38 of the electrode member 30 is disposed in one of the two bottom surface recesses 18a, and the bottom plate portion 48 of the electrode member 40 is disposed in the other bottom surface recess 18a.

[0032] The coil element 20 is provided inside the magnetic core 10. In other words, the entire coil element 20 is embedded in the magnetic core 10.

[0033] The coil element 20 is formed, for example, by a single conductor wire. For example, the conductor wire is a round wire with a cross-sectional diameter of 0.5 mm. The diameter of the conductor wire is appropriately selected from the range of 0.2 mm to 1 mm. The conductor wire is composed of a metal wire made of a metal material selected from metals such as aluminum, copper, silver, and gold, alloys containing one or more of these metals, and materials made of metals or alloys and other substances, and an insulating coating that covers the metal wire. Specifically, the conductor wire is, for example, a copper wire coated with an insulating coating.

[0034] Coil element 20 has winding portion 21 around which a conductor is wound, and multiple lead portions 23 and 24 that are conductors drawn out from the ends of winding portion 21. In this example, coil element 20 is composed of one winding portion 21 and two lead portions 23, 24. Winding portion 21 and lead portions 23, 24 are names given to respective portions formed, for example, by processing a single wire made of the same material. Coil element 20 is disposed within magnetic core 10 so that winding axis 21c of winding portion 21 is perpendicular to bottom surface 18 and top surface 19.

[0035] The winding portion 21 is made up of a wound conductor and functions as a coil. The winding portion 21 is composed of an inner coil and an outer coil connected to the inner coil. The number of turns of the inner coil and the outer coil is two each. There is no particular limitation on the number of turns of the winding portion 21, and it is selected appropriately according to the performance required of the inductor 1 and constraints such as the size of the magnetic core 10. Lead portions 23 and 24 are connected to both ends of the winding portion 21, respectively. Specifically, the lead portion 23 is connected to the end of the inner coil, and the lead portion 24 is connected to the end of the outer coil.

[0036] The lead portions 23, 24 are made of straight conductors. The lead portions 23, 24 are arranged along one diagonal of the rectangular top surface 19. The lead portions 23, 24 are drawn from the end of the winding portion 21 toward the surface of the magnetic core 10 and terminate before reaching the surface of the magnetic core 10. The distance from the end of the lead portion 23 to the end of the lead portion 24 is longer than the distance from the end face 13 to the end face 14 (or the distance from the protrusion 33 to the protrusion 43) and shorter than the length of the diagonal of the magnetic core 10.

[0037] One lead portion 23 is arranged at corner 10r of magnetic core 10 where end face 13 and side face 15 intersect when viewed from a direction perpendicular to top surface 19 (Z-axis direction). The other lead portion 24 is arranged at corner 10r of magnetic core 10 where end face 14 and side face 16 intersect when viewed from a direction perpendicular to top surface 19. In other words, lead portions 23 and 24 are each arranged at corners 10r that face diagonally opposite corners of square-shaped top surface 19. By arranging lead portions 23 and 24 at corners 10r of magnetic core 10, the volume of magnetic core 10 can be used effectively, and the superposition characteristics of inductor 1 can be improved.

[0038] Furthermore, when viewed from a direction perpendicular to end face 13, lead portion 23 is located closer to top face 19 than the center of end face 13, specifically closer to top face 19 than a first lead portion 31 described later. When viewed from a direction perpendicular to end face 14, lead portion 24 is located closer to top face 19 than the center of end face 14, specifically closer to top face 19 than a first lead portion 41 described later.

[0039] The insulating coating of the lead portions 23, 24 has been removed so that they can be electrically connected to the electrode members 30, 40, respectively. The lead portion 23 is crimped to a connection portion 34 of the electrode member 30 and then welded to be connected and fixed to the electrode member 30. The lead portion 24 is crimped to a connection portion 44 of the electrode member 40 and then welded to be connected and fixed to the electrode member 40.

[0040] The electrode member 30 and the lead portion 23, and the electrode member 40 and the lead portion 24 have shapes and positions that are symmetrical about 180° with respect to the winding axis 21c. In the following, of the electrode members 30 and 40, the electrode member 30 will be described as an example.

[0041] 5A and 5B , the electrode member 30 has a side plate portion 35 and a bottom plate portion 38. The electrode member 30 also has a first lead portion 31, a connection portion 34, a protrusion 33, a second lead portion 32, a first groove portion 36, and a second groove portion 37.

[0042] The electrode member 30 is formed, for example, from a metal plate. The metal plate is made 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. The thickness of the metal plate is, for example, 0.15 mm. The side plate portion 35, the first lead portion 31 and the connection portion 34, the second lead portion 32, the protrusion portion 33, and the bottom plate portion 38 are names given to respective portions formed, for example, by processing a single plate made of the same material. The first groove portion 36 and the second groove portion 37 are notched grooves that facilitate bending of the first lead portion 31 and the second lead portion 32, respectively.

[0043] The side plate portion 35 is disposed along the end face 13 of the magnetic core 10 on the outside of the magnetic core 10. The side plate portion 35 is plate-shaped and in contact with the end face 13. In a direction perpendicular to the top face 19, the length of the side plate portion 35 is shorter than the length (height) of the end face 13. An end portion 35a of the side plate portion 35 on the top face 19 side is located closer to the bottom face 18 than the top face 19, and an end portion 35b of the side plate portion 35 on the bottom face 18 side is located closer to the bottom face 18 than the end portion 35a and at approximately the same height as the bottom face 18.

[0044] The bottom plate portion 38 is connected to the end portion 35b of the side plate portion 35 on the bottom surface 18 side, and is pulled out from the end portion 35b on the bottom surface 18 side to extend along the bottom surface 18. Specifically, the bottom plate portion 38 is bent starting from the end portion 35b of the side plate portion 35 on the bottom surface 18 side, and is arranged so that at least a portion of it fits into the bottom surface recess 18a.

[0045] The outer surfaces of the side plate portion 35 and the bottom plate portion 38 are exposed and not embedded in the magnetic core 10. The side plate portion 35 and the bottom plate portion 38 are joined to the circuit board by solder or the like when the inductor 1 is mounted on the circuit board.

[0046] The first lead portion 31, the connection portion 34, and the second lead portion 32 are embedded in the magnetic core 10. In the present embodiment, the first lead portion 31, the connection portion 34, and the second lead portion 32 are embedded in the magnetic core 10, so that the electrode member 30 does not fall out of the magnetic core 10.

[0047] The first lead portion 31 is connected to an end 35a of the side plate portion 35 on the top surface 19 side, and extends from the end 35a on the top surface 19 side into the interior of the magnetic core 10. The first lead portion 31 is formed by bending the end 35a of the side plate portion 35 on the top surface 19 side as a starting point. The first lead portion 31 is disposed parallel to the top surface 19.

[0048] The connection portion 34 is connected to the first lead portion 31 and connected to the lead portion 23 inside the magnetic core 10. The connection portion 34 is fixed by crimping so as to wrap around and cover at least half the circumference of the outer periphery of the lead portion 23. The connection portion 34 is further joined to the lead portion 23 by laser welding.

[0049] Here, the connection portion 34 includes, in order from closest to the first lead portion 31, a second crimping portion 34b (see FIG. 8) and a first crimping portion 34a (see FIG. 8). The second crimping portion 34b sandwiches the lead portion 23 from the bottom surface 18 side, and the first crimping portion 34a sandwiches the lead portion 23 from the top surface 19 side, and they are crimped together with the lead portion 23. As shown in FIG. 6, a first melting mark 34ma is formed on the first crimping portion 34a on the top surface 19 side due to laser welding. As shown in FIG. 7, a second melting mark 34mb is formed on the second crimping portion 34b on the bottom surface 18 side due to laser welding. The laser welding is performed by irradiating a laser beam only from one side of the top surface 19, and between the first fusion mark 34ma and the second fusion mark 34mb, a part of the connection portion 34 and a part of the lead portion 23 are melted by the welding and then solidified (melted and solidified) to form a welded portion 34m. The welded portion 34m is both a part of the connection portion 34 and a part of the lead portion 23.

[0050] The second lead-out portion 32 is connected to an end 35a of the side plate portion 35 on the top surface 19 side, and extends from the end 35a on the top surface 19 side into the interior of the magnetic core 10. The second lead-out portion 32 is formed by bending the side plate portion 35 from the end 35a on the top surface 19 side as a starting point. The second lead-out portion 32 is disposed parallel to the top surface 19. The second lead-out portion 32 does not have a connecting portion, but has a through hole 32h formed therein to enhance prevention of disconnection.

[0051] The protruding portion 33 is connected to the end 35a of the side plate portion 35 on the top surface 19 side, and protrudes further toward the top surface 19 from the end 35a on the top surface 19 side. The protruding portion 33 is arranged along the end face 13, and the outer surface of the protruding portion 33 is not embedded in the magnetic core 10. Note that, for example, the protruding portion 33 may be slightly bent toward the center 10c of the magnetic core 10 from the end 35a on the top surface 19 side of the side plate portion 35 as a starting point, and the tip 33e of the protruding portion 33 may be embedded in the magnetic core 10. Alternatively, the side plate portion 35 and the protruding portion 33 may be at least partially or entirely embedded in a 0.15 mm thick metal plate and fixed in the magnetic core 10, and the bottom plate portion 38 may not be embedded in the magnetic core 10. By embedding and fixing the side plate portion 35 and the protrusion portion 33 in the magnetic core 10, vibration resistance can be ensured, and since the bottom plate portion 38 is not fixed to the magnetic core 10, heat cycle resistance can be improved.

[0052] The first groove 36 is provided at an end 35a of the side plate 35 on the top surface 19 side, between the first lead portion 31 and the protrusion 33. The first groove 36 is a groove that extends in the thickness direction of the side plate 35. The groove width of the first groove 36 is desirably smaller than the width of the cross section of the conducting wire that forms the coil element 20. The groove width of the first groove 36 is, for example, not less than 0.2 mm and not more than 0.4 mm.

[0053] The second groove 37 is provided between the second drawer 32 and the protrusion 33 at the end 35a of the side plate 35 on the top surface 19 side. The second groove 37 is a groove that progresses in the thickness direction of the side plate 35. It is desirable that the groove width of the second groove 37 be the same as the groove width of the first groove 36.

[0054] In this way, the end 35a of the side plate 35 on the top surface 19 side is provided with the protrusion 33, the first groove 36, the second groove 37, the first lead-out portion 31, and the second lead-out portion 32. The protrusion 33, the first groove 36, the second groove 37, the first lead-out portion 31, and the second lead-out portion 32 are provided in different regions of the end 35a of the side plate 35 on the top surface 19 side.

[0055] When viewed from a direction perpendicular to the top surface 19 (the Z-axis direction), the protrusion 33 is positioned so as to overlap a line 10cL that passes through the center 10c of the magnetic core 10 and is perpendicular to the end surface 13 (see FIG. 4A ). In other words, the protrusion 33 is positioned at the center of the side plate portion 35 in a direction perpendicular to the side surface 15. A first groove 36 and a second groove 37 are provided on both outer sides of the protrusion 33. That is, the first groove 36 is provided on the side surface 15 side when viewed from the protrusion 33. The first lead-out portion 31 is provided further toward the side surface 15 than the first groove 36. The second groove 37 is provided on the side surface 16 side when viewed from the protrusion 33. The second lead-out portion 32 is provided further toward the side surface 16 than the second groove 37.

[0056] In this embodiment, when viewed from a direction perpendicular to the end face 13, the tip 33e of the protrusion 33 is located closer to the top surface 19 than the first lead portion 31. Furthermore, when compared in terms of position coordinates in a direction perpendicular to the top surface 19 (the Z-axis direction), the tip 33e of the protrusion 33 is located closer to the top surface 19 than the guide surface 31g of the first lead portion 31 on the top surface 19 side, and is located closer to the bottom surface 18 than the edge 34e of the connection portion 34 on the top surface 19 side. The dimension by which the protrusion 33 protrudes toward the top surface 19 from the first lead portion 31 is preferably smaller than the height dimension of the cross section of the conductor forming the coil element 20. The protrusion height by which the protrusion 33 protrudes toward the top surface 19 from the first lead portion 31 is, for example, 0.1 mm or more and 0.4 mm or less. The guide surface 31g is a surface that abuts against the lower end of the lead portion 23 when the lead portion 23 slides on the first lead portion 31 and moves toward the connection portion 34.

[0057] By providing the protrusion 33 so that the tip 33e of the protrusion 33 is located closer to the top surface 19 than the first lead portion 31, for example, when the lead portion 23 of the coil element 20 is placed on the tip 33e of the protrusion 33 and the coil element 20 is rotated to move the lead portion 23, the lead portion 23 does not get caught on the electrode member 30 and can be moved smoothly to the connection portion 34. This prevents the lead portion 23 of the coil element 20 from being damaged and prevents a decrease in the reliability of the inductor 1. Furthermore, since the lead portion 23 can be reliably placed on the connection portion 34, the connection reliability between the lead portion 23 and the connection portion 34 can be improved. Furthermore, since the positional accuracy of the lead portion 23 and the connection portion 34 relative to the magnetic core 10 is improved, the vibration resistance of the inductor 1 can be improved.

[0058] Here, we consider whether the fusion connection between the connection portion 34 and the lead portion 23 is performed using laser light from the top surface 19 side or from the bottom surface 18 side. Here, a case where the fusion connection between the connection portion 34 and the lead portion 23 is performed using laser light from the top surface 19 side is referred to as an example (shown as an open circle in FIGS. 9 to 13 , which will be described later), and a case where the fusion connection between the connection portion 34 and the lead portion 23 is performed using laser light from the bottom surface 18 side is referred to as a comparative example (shown as a filled circle in FIGS. 9 to 13 , which will be described later). However, the following description does not apply to cases where the first crimped portion 34 a on the top surface 19 side and the second crimped portion 34 b on the bottom surface 18 side are arranged in descending order of proximity from the first lead portion 31. When determining whether the fusion connection between the connection portion 34 and the lead portion 23 is performed using laser light from the top surface 19 side or from the bottom surface 18 side, it is important to perform the connection from the surface of the crimped portion farthest from the first lead portion 31. In other words, whether the fusion connection between the connection portion 34 and the lead portion 23 is performed using laser light from the top surface 19 side or from the bottom surface 18 side, it is important to perform the connection from the surface of the crimping portion closest to the edge 34e.

[0059] FIG. 9 is a graph comparing the DCR characteristics (DC resistance characteristics) of the inductor according to the embodiment with those of a comparative example. FIG. 10 is a graph comparing the film foaming distance of the inductor according to the embodiment with those of a comparative example. FIG. 11 is a graph showing the relationship between the bottom molten area and the ratio of the total molten area / conductor cross-sectional area of ​​the inductor according to the embodiment. FIG. 12 is a graph comparing the DCR characteristics of the inductor according to the embodiment with those of a comparative example. FIG. 13 is a graph comparing the DCR characteristics of the inductor according to the embodiment with those of a comparative example. FIG. 14 is a graph for explaining a crystal orientation analysis of the inductor according to the embodiment.

[0060] 9, the DCR (direct current resistance) versus laser output of the example exhibits lower values ​​in the low laser output range (less than 1250 W) compared to the comparative example. The lower the DCR, the better the characteristics of the inductor 1. Therefore, the example exhibiting a low DCR is more advantageous than the comparative example when performing a fusion connection between the connection portion 34 and the lead portion 23 using a low laser output. For example, since the insulating coating of the conductor may be deteriorated by the heat during welding, it is useful to be able to achieve a low DCR with a low laser output.

[0061] 10, the coating foaming distance (the distance from the welded portion 34m at which foaming (deterioration) occurs in the insulating coating) is shorter in the example than in the comparative example in the low laser power range (less than 1250 W). In other words, it can be said that fusing the connection portion 34 and the lead portion 23 with a laser beam from the top surface 19 side is less likely to cause foaming in the insulating coating of the conductor than using a laser beam from the bottom surface 18 side.

[0062] This can be explained as follows. First, when laser light is irradiated from the top surface 19 side, the laser light strikes the surface of the first crimped portion 34a, generating heat and melting the first crimped portion 34a, the lead portion 23, and the second crimped portion 34b in that order. The first crimped portion 34a is close to the edge 34e, so the heat is less likely to reach other portions of the connection portion 34, and the first crimped portion 34a is heated efficiently. This then makes it easier for heat to reach the lead portion 23 from the first crimped portion 34a, and the lead portion 23 is also heated efficiently. Here, the heat reaching the lead portion 23 from the lead portion 23 to the winding portion 21 causes foaming of the insulating coating, but because the second crimped portion 34b, which has not yet been fully heated, is nearby, the heat from the lead portion 23 is distributed to the winding portion 21 and the second crimped portion 34b. In particular, the second crimped portion 34b is thermally connected to the other portions of the electrode member 30, and therefore is not easily heated, and a large amount of heat is distributed to the second crimped portion 34b. As a result, the amount of heat given to the winding portion 21 until the welded portion 34m is formed is relatively small.

[0063] On the other hand, when laser light is irradiated from the bottom surface 18 side, the laser light strikes the surface of the second crimped portion 34b, generating heat and melting the second crimped portion 34b, the lead portion 23, and the first crimped portion 34a in that order. Because the second crimped portion 34b is thermally connected to other portions of the electrode member 30, the heat spreads to other portions of the connection portion 34, causing heating to proceed inefficiently. Heat then spreads from the second crimped portion 34b to the lead portion 23, and is used to melt the lead portion 23 and distribute the heat to the winding portion 21 and the first crimped portion 34a. Because the first crimped portion 34a is close to the edge 34e, the first crimped portion 34a is heated efficiently. As a result, a relatively large amount of heat is applied to the winding portion 21 before the weld 34m is formed.

[0064] Thus, when irradiating laser light from either the top surface 19 side or the bottom surface 18 side, it can be said that irradiating the laser light from the surface of the crimped portion closer to the edge 34e (here, the top surface 19) is more likely to suppress deterioration of the inductor 1. Here, the first crimped portion 34a is melted before the second crimped portion 34b, so the first melted mark 34ma, which is the melted mark formed on that surface, has a larger area than the second melted mark 34mb, which is the melted mark formed on the surface on the bottom surface 18 side. An appropriate value for the area of ​​such a melted mark will be defined using Figures 11 to 13.

[0065] As shown in FIG. 11 , when the sum of the surface areas of the first melt mark 34ma and the second melt mark 34mb (total melted area) exceeds 50% of the cross-sectional area of ​​the conductor (here, the cross-sectional area of ​​the wire without deformation such as crimping), the surface area of ​​the second melt mark 34mb becomes greater than 0. In other words, a weld 34m can be formed that extends to the surface of the second crimped portion 34b. However, even if the weld 34m does not extend to the surface of the second crimped portion 34b, electrical connection between the connection portion 34 and the lead portion 23 is possible as long as the weld 34m is formed into the second crimped portion 34b. Therefore, it is preferable that the total melted area relative to the cross-sectional area of ​​the conductor be, for example, 20% or more. This can also be seen from the fact that the DCR value in FIG. 12 is within the standard value (8.48 mΩ). In practice, the inductor 1 must be manufactured within a safety range that takes into account manufacturing errors, etc., and therefore, as shown in FIG. 13 , a target value of within 2% of the standard value of 8.2 mΩ should be achieved. In terms of such criteria, the total melting area relative to the cross-sectional area of ​​the conductor is preferably, for example, 50% or more. Note that such specific values ​​may vary depending on the cross-sectional area and material of the wire, and may be determined empirically or through prior experiments, as appropriate.

[0066] Further, appropriate values ​​for the crystalline state within the weld 34m will be defined below using FIG. 14 . FIG. 14 shows the results of crystal orientation analysis of a cross section of the lead 23 and connection 34 that were actually fusion-connected, taken from the same perspective as FIG. 8A. Specifically, it shows an inverse pole figure orientation map of electron backscatter diffraction (EBSD). In the figure, areas with different contrast indicate grains with different crystal orientations. The weld 34m is indicated by a bold white line. Additionally, areas a, b, c, d, g, h, i, and k (areas a, b, and c are the weld 34m) for analyzing each area are individually delimited by dashed lines.

[0067] The area average diameter D of the crystalline structure in the weld 34 m ＭＡ There is an appropriate range from the viewpoint of ensuring the strength of the welded portion 34m, and it is preferable that the diameter is, for example, 5 μm or more and 100 μm or less. As an example, for the welding and the forming of the magnetic core 10, three different conditions are set within the standard values, and the area mean diameter D ＭＡ The area mean diameter D (μm) was calculated and evaluated under the conditions where the welding was within the standard value (specifically, the welding conditions where the total melting area relative to the cross-sectional area of ​​the conductor was 112% and the conductor was in a state before being embedded in the magnetic core 10). ＭＡ As shown in Table 1, the thicknesses of the areas a, b, c, d, g, h, i, and k were 13.6 μm, 11.2 μm, 21 μm, 6.3 μm, 6.5 μm, 8.6 μm, 8 μm, and 6.3 μm, respectively.

[0068]

[0069] Under conditions where welding and molding are within the standard values ​​(specifically, welding conditions where the total melting area relative to the cross-sectional area of ​​the conductor is 112% and the part of the magnetic core 10 where the density of the metal magnetic powder is lowest is aligned with the position of the lead portions 23 and 24), the area mean diameter D ＭＡAs shown in Table 2, the average particle diameters were 33.2 μm, 23.1 μm, 30.8 μm, N.A., 5.8 μm, 7.1 μm, N.A., and 6.2 μm in areas a, b, c, d, g, h, i, and k, respectively. N.A. means that measurement was not possible.

[0070]

[0071] Under conditions where welding is within the standard values ​​and molding is within the upper limit of the standard values ​​(specifically, welding conditions where the total melting area relative to the cross-sectional area of ​​the conductor is 89%, and the part of the magnetic core 10 where the density of the metal magnetic powder is lowest is moved 0.28 mm toward the bottom surface 18 relative to the positions of the lead portions 23 and 24), the area average diameter D ＭＡ As shown in Table 3, the thicknesses of the areas a, b, c, d, g, h, i, and k were 19.2 μm, 23.7 μm, 26 μm, N.A., 8.8 μm, 7.6 μm, N.A., and 6.8 μm, respectively.

[0072]

[0073] Area average diameter D ＭＡ In the figure, the welded portion 34m (areas a, b, c) showed 11 μm to 34 μm, and the non-welded portion (areas d, g, h, i, k) showed 5 μm to 9 μm.

[0074] In addition, crystal structure D ＭＡ The calculation formula for is as follows: (1) where S represents the crystal grain area, which is measured using particle size analysis software, and DH represents the Heywood diameter calculated from the crystal grain area using the particle size analysis software.

[0075]

[0076] Area average aspect ratio AR of the crystalline structure in the weld 34 m ＭＡ The smaller the crystal strain, the better from the viewpoint of ensuring the strength of the welded portion 34m, and for example, it is preferable that the value be 7 or less. As an example, for welding and forming, three different conditions are set within the standard values, and the area average aspect ratio AR ＭＡThe area average aspect ratio AR was calculated and evaluated under the conditions where the welding was within the standard values ​​(specifically, under the welding conditions where the total melting area relative to the cross-sectional area of ​​the conductor was 112% and in the state before being embedded in the magnetic core 10). ＭＡ As shown in Table 4, the values ​​were 1.98, 1.80, 1.90, 1.84, 1.88, 2.39, 2.01, and 1.87 in areas a, b, c, d, g, h, i, and k, respectively.

[0077]

[0078] Under conditions where welding and molding are within the standard values ​​(specifically, welding conditions where the total melting area relative to the cross-sectional area of ​​the conductor is 112% and the part of the magnetic core 10 where the density of the metal magnetic powder is lowest is aligned with the position of the lead portions 23 and 24), the area average aspect ratio AR ＭＡ As shown in Table 5, the values ​​were 1.72, 2.20, 2.19, N.A., 1.83, 2.24, N.A., and 1.85 in areas a, b, c, d, g, h, i, and k, respectively.

[0079]

[0080] Under the conditions where welding and molding are at the upper limit of the standard values ​​(specifically, the welding conditions are such that the total melting area relative to the cross-sectional area of ​​the conductor is 89%, and the part of the magnetic core 10 where the density of the metal magnetic powder is lowest is moved 0.28 mm toward the bottom surface 18 relative to the positions of the lead portions 23 and 24), the area average aspect ratio AR ＭＡ As shown in Table 6, the values ​​were 2.02, 3.49, 2.41, N.A., 1.93, 1.95, N.A., and 2.16 in areas a, b, c, d, g, h, i, and k, respectively.

[0081]

[0082] Area average aspect ratio AR ＭＡ In the test, the welded area 34m (areas a, b, c) showed a value of 1.8 to 3.5, and the non-welded area (areas d, g, h, i, k) showed a value of 1.8 to 2.4.

[0083] The area average aspect ratio AR ＭＡThe calculation formula is as follows: (2) where AR indicates the ratio of the maximum Feret diameter to the minimum Feret diameter calculated using particle size analysis software.

[0084]

[0085] Of the electrode members 30 and 40, the electrode member 30 has been described above as an example, but the same can be said for the electrode member 40. In that case, the following configuration with interchanged reference numerals is established.

[0086] For example, the electrode member 30 in the above may be replaced with the electrode member 40, the first lead portion 31 with the first lead portion 41, the guide surface 31g with the guide surface 41g, the second lead portion 32 with the second lead portion 42, the through hole 32h with the through hole 42h, the protrusion 33 with the protrusion 43, the tip 33e with the tip 43e, the connection portion 34 with the connection portion 44, the first melting mark 34ma with the first melting mark 44ma, the second melting mark 34 The same result can be obtained by replacing mb with the second melting mark 44mb, edge 34e with edge 44e, side plate portion 35 with side plate portion 45, end portion 35a with end portion 45a, end portion 35b with end portion 45b, first groove portion 36 with first groove portion 46, second groove portion 37 with second groove portion 47, bottom plate portion 38 with bottom plate portion 48, end face 13 with end face 14, side surface 15 with side surface 16, and lead portion 23 with lead portion 24.

[0087] [Method for Manufacturing Inductor] A method for manufacturing the inductor 1 will be described with reference to FIGS.

[0088] FIG. 15 is a flowchart showing a method for manufacturing the inductor 1 according to the embodiment.

[0089] The manufacturing method of the inductor 1 includes a coil element forming step S10, an electrode member pre-forming step S20, a connection step S30, and a magnetic core forming step S40. The manufacturing method of the inductor 1 also includes a bottom plate portion forming step S50.

[0090] FIG. 16 is a diagram showing the coil element 20 formed in the coil element forming step S10.

[0091] In the coil element formation process S10, a coil element 20 is formed, which has a winding portion 21 around which a conductor wire is wound and lead portions 23, 24 drawn out from the ends of the winding portion 21. The insulating coating of the conductor wire is removed from at least a portion of the lead portions 23, 24.

[0092] 17 is a diagram showing the electrode members 30, 40 formed in the electrode member pre-forming step S20. While the figure shows an example in which the electrode members 30, 40 are formed from hoop material, the present invention is not limited to this, and the electrode members 30, 40 may be fixed to a transport jig by positioning pins or the like.

[0093] In the electrode member pre-forming step S20, the electrode members 30 and 40 are pre-formed.

[0094] In this step S20, an electrode member 30 is pre-formed, which has a side plate portion 35 arranged along a predetermined direction, a first draw-out portion 31 bent at one end 35a of the side plate portion 35 in the predetermined direction, a connection portion 34 extending from the first draw-out 31, and a protrusion 33 protruding in a predetermined direction from one end 35a of the side plate portion 35 in the predetermined direction.

[0095] The preformed electrode member 30 is in a state before it is crimped, and the connection portion 34 has an opening for inserting the lead portion 23 in a subsequent process. The preformed electrode member 30 is in a state before the bottom plate portion 38 is bent, and the lower portions of the side plate portions 35 form the leg portions 38a. The predetermined direction is the direction in which the leg portions 38a extend straight.

[0096] In addition, in this process S20, an electrode member 40 is pre-formed, which has a side plate portion 45 arranged along a predetermined direction, a first draw-out portion 41 bent at one end 45a of the side plate portion 45 in the predetermined direction, a connection portion 44 extending from the first draw-out 41, and a protrusion 43 protruding in a predetermined direction from one end 45a of the side plate portion 45 in the predetermined direction.

[0097] The preformed electrode member 40 is in a state before it is crimped, and the connection portion 44 has an opening for inserting the lead portion 24 in a subsequent process. The preformed electrode member 40 is in a state before the bottom plate portion 48 is formed by bending, and the lower portions of the side plate portions 45 form the leg portions 48a. The predetermined direction is the direction in which the leg portions 48a extend straight.

[0098] FIG. 18 is a diagram showing an example of a connecting step S30 for connecting the coil element 20 and the electrode members 30 and 40.

[0099] In the connecting step S30, the lead portion 23 and the connecting portion 34 are connected, and the lead portion 24 and the connecting portion 44 are connected.

[0100] Specifically, as shown in (a) of Figure 18, the winding portion 21 of the coil element 20 is inserted into the support 61 of the transport jig, and the lead portion 23 is placed on the tip 33e of the protrusion 33, and the lead portion 24 is placed on the tip 43e of the protrusion 43.

[0101] Next, as shown in FIG. 18B, the winding portion 21 and the lead portions 23 and 24 of the coil element 20 are rotated around the winding axis 21c. In the figure, the lead portion 23 is rotated by pushing and rotating the coil element 20 using the rotating member 62. As a result, as shown in FIG. 18C, the lead portion 23 is moved from its position on the protrusion 33, over the first lead portion 31, to the connection portion 34. At the same time, the lead portion 24 is moved from its position on the protrusion 43, over the first lead portion 41, to the connection portion 44 (not shown). Specifically, the lead portion 23 is moved while in contact with the protrusion 33 and the first lead portion 31, and inserted into the opening of the connection portion 34, and the lead portion 24 is moved while in contact with the protrusion 43 and the first lead portion 41, and inserted into the opening of the connection portion 44.

[0102] 18(d), the lead portion 23 and the connecting portion 34 are connected by crimping using a crimping jig (not shown). Specifically, the lead portion 23 is sandwiched and crimped between the second crimping portion 34b and the first crimping portion 34a. Similarly, the connecting portion 44 is connected to the lead portion 24 by crimping using the crimping jig. After being crimped, the lead portion 23 and the connecting portion 34, and the lead portion 24 and the connecting portion 44 are joined by laser welding. Specifically, as shown by the white arrow in Figure 18(d), the surface of the first crimped portion 34a is irradiated with laser light in a direction from the surface of the first crimped portion 34a toward the surface of the second crimped portion 34b. As shown in Figures 6 to 8, a first melting mark 34ma is formed on the surface of the first crimped portion 34a, where the first crimped portion 34a melts and solidifies, and a second melting mark 34mb is formed on the surface of the second crimped portion 34b, where the second crimped portion 34b melts and solidifies (see Figure 8). A weld 34m is formed between the first melting mark 34ma and the second melting mark 34mb, and the connection portion 34 and the lead portion 23 are melt-connected between the first melting mark 34ma and the second melting mark 34mb. The lead portion 24 and the connection portion 44 are melt-connected in the same manner.

[0103] In the magnetic core forming step S40, the coil element 20, the first lead portions 31, 41, and the connecting portions 34, 44 are embedded in the magnetic core 10. Note that the side plate portions 35, 45 and the protruding portions 33, 43 may be partially embedded in the magnetic core 10 in the thickness direction. This step S40 is performed by placing the coil element 20, the first lead portions 31, 41, and the connecting portions 34, 44 in a molding die and pressure-molding the mixture that will become the material for the magnetic core 10. During this molding, a bottom surface recess 18a is formed in the bottom surface 18 of the magnetic core 10 at a position that overlaps the bottom plate portion 38.

[0104] In the bottom plate portion forming step S50, the bottom plate portions 38, 48 are formed by bending the lower portions of the side plate portions 35, 45. The tips of the bottom plate portions 38, 48 are bent so as to fit into the bottom surface recess 18a.

[0105] According to this manufacturing method, when the lead portions 23, 24 are rotated, they move smoothly over the protrusions 33, 43 and the first lead portions 31, 41, respectively, and are positioned at the connection portions 34, 44. This prevents the lead portions 23, 24 from being damaged, and reduces the reliability of the inductor 1. Furthermore, this prevents the lead portions 23, 24 from getting caught on the electrode members 30, 40, respectively, and therefore reduces a decrease in production efficiency. After being fixed by crimping, the lead portions 23, 24 are further fusion-connected to the respective connection portions 34, 44 in a manner that suppresses foaming of the insulating coating. This improves the DCR characteristics while suppressing deterioration of the insulating coating, and allows the manufacture of a more reliable inductor 1.

[0106] [Modifications] Modifications will be described below with reference to Figures 19A to 19F. Figures 19A to 19F are diagrams illustrating weld marks on an inductor according to a modification of the embodiment. In each of Figures 19A to 19F, (a) shows the shape of a first melt mark 34ma, and (b) shows the shape of a second melt mark 34mb. In the figures, the two-dot chain line indicates the trajectory of the laser beam movement, and the overlapping circles along this trajectory indicate how the weld mark expands as the laser beam moves. Since there are no differences other than the shapes of the first melt mark 34ma and the second melt mark 34mb, illustrations of other configurations are omitted.

[0107] For example, in the above embodiment, a case where a circular weld mark is formed has been described, but the shape of the weld mark is not limited to a circle. For example, by moving the laser beam on a circular orbit, a substantially circular shape with a shifted circle can be formed as shown in Fig. 19A. Furthermore, by moving the laser beam on a circular orbit or an arcuate orbit with an increased diameter, a ring shape with a shifted circle can be formed as shown in Fig. 19B. Furthermore, by moving the laser beam on a circular orbit or an arcuate orbit with an increased diameter, a open ring shape with a shifted circle can be formed as shown in Fig. 19C.

[0108] 19A to 19C, it is preferable to set the positions where the laser light is first irradiated and where it is last irradiated to be far from the insulating coating of each of the lead portions 23, 24, in other words, on the distal end side of each of the lead portions 23, 24. By doing so, it is possible to further prevent the insulating coating of the lead portions 23, 24 from being affected by heat and from deteriorating.

[0109] Furthermore, by moving the laser beam on a linear trajectory, it is possible to obtain a linear molten mark with a moving circle, as shown in Fig. 19D. When moving the laser beam on a linear trajectory, by adjusting the output power and moving speed of the laser beam while moving the laser beam, it is possible to obtain a linear molten mark with circles of approximately the same size at each point in time, as shown in Fig. 19E. Furthermore, by moving the laser beam on an amplitude trajectory, it is possible to obtain a zigzag shaped molten mark with a moving circle, as shown in Fig. 19F.

[0110] 19D to 19F, the temperatures of the leads 23, 24, first crimping portion 34a, and second crimping portion 34b at the final irradiation of the laser beam will be higher than the temperatures at the initial irradiation of the laser beam, so it is preferable to set the positions at which the laser beam is finally irradiated to positions far from the insulating coating of the leads 23, 24, in other words, toward the distal ends of the leads 23, 24. This makes it possible to further prevent the insulating coating of the leads 23, 24 from being affected by heat and deteriorating.

[0111] 19D and 19E, by adjusting the output power and moving speed of the laser beam while moving it, it is possible to form a melted mark of any shape along any trajectory. However, as shown in the combination of (a) and (b) in each figure, since the laser beam is irradiated from the first crimped portion 34a toward the second crimped portion 34b, the area of ​​the first melted mark 34ma is larger than that of the second melted mark 34mb in either case.

[0112] (Summary) An inductor and a manufacturing method thereof according to one aspect of the present disclosure will be exemplified.

[0113] [Example 1] Inductor 1 of Example 1 includes magnetic core 10 having bottom surface 18, top surface 19 facing away from bottom surface 18, and end surface 13 connecting bottom surface 18 and top surface 19, coil element 20 embedded in magnetic core 10, and electrode member 30 connected to coil element 20. Coil element 20 has winding portion 21 around which a conductor with an insulating coating is wound, and lead portion 23 drawn out from an end of winding portion 21. The electrode member 30 has a side plate portion 35 arranged along the end face 13, a first lead-out portion 31 extending from an end portion 35a of the side plate portion 35 on the top face 19 side into the interior of the magnetic core 10, and a connection portion 34 connected to the first lead-out portion 31 and including a second crimping portion 34b and a first crimping portion 34a in that order from closest to the first lead-out portion 31, the connection portion 34 being crimped inside the magnetic core 10 with the second crimping portion 34b and the first crimping portion 34a sandwiching the lead portion 23. The connection portion 34 has a first melting mark 34ma which is a melting mark formed on the surface of the first crimping portion 34a where the first crimping portion 34a has melted and solidified, a second melting mark 34mb which is a melting mark formed on the surface of the second crimping portion 34b where the second crimping portion 34b has melted and solidified, and a welding portion 34m between the first melting mark 34ma and the second melting mark 34mb where the connection portion 34 and the lead portion 23 have melted and solidified.

[0114] By doing this, a joint with low DC resistance is obtained by melting the first crimping portion 34a, the lead portion 23, and the second crimping portion 34b sandwiched between the first melting mark 34ma and the second melting mark 34mb, thereby improving the DC resistance characteristics (DCR characteristics) and realizing an inductor 1 that can suppress a decrease in reliability.

[0115] Example 2 The inductor 1 of Example 2 is the inductor 1 described in Example 1, in which the area of ​​the first melting mark is larger than the area of ​​the second melting mark.

[0116] This configuration allows for the formation of a weld 34m, which is tapered from the first crimped portion 34a toward the second crimped portion 34b. This can be achieved by irradiating a laser beam from the first crimped portion 34a toward the second crimped portion 34b. At the initial stage of welding to form the weld 34m, the portion irradiated with the laser beam (i.e., the portion where the first melting mark is formed) is close to the edge 34e of the connection portion 34, so melting begins with a small amount of heat. As melting progresses, heat imparted to the lead portion 23 is easily conducted from the backside (i.e., the second crimped portion 34b) to the side plate portion 35, which is the main body of the electrode member. This configuration achieves a joint with low DC resistance and easily suppresses heat-induced deterioration of the insulating coating of the conductor during welding. This allows for the realization of an inductor 1 that is less likely to impair the insulating function of the insulating coating and suppresses a decrease in reliability.

[0117] [Example 3] The inductor 1 of Example 3 is the inductor 1 described in Example 1 or Example 2, in which the sum of the area of ​​the first melting mark 34ma and the area of ​​the second melting mark 34mb is 20% or more of the cross-sectional area of ​​the conductor wire.

[0118] According to this configuration, the cross-sectional area of ​​the welded portion 34m can be easily enlarged relative to the cross-sectional area of ​​the conductor wire, and it is easy to realize an inductor 1 with improved DC resistance characteristics.

[0119] [Example 4] The inductor 1 of Example 4 is the inductor 1 described in any one of Examples 1 to 3, in which the area mean diameter of the crystalline structure of the welded portion is larger than the area mean diameter of the crystalline structure of the connection portion 34 other than the welded portion 34m, and the area mean diameter of the crystalline structure of the welded portion 34m is 5 μm or more and 100 μm or less.

[0120] According to this configuration, the area average diameter of the crystalline structure of the welded portion 34m is larger than the area average diameter of the surrounding welded portion 34m in the connection portion 34, and by setting the area average diameter of the crystalline structure of the welded portion 34m to be 5 μm or more and 100 μm or less, it is possible to ensure the strength to keep the welded portion 34m resistant to collapse, and by setting the area average aspect ratio of the crystalline structure of the welded portion 34m to be 7 or less, it is possible to reduce crystal distortion, thereby further improving the strength of the welded portion 34m.

[0121] Example 5 A method for manufacturing an inductor 1 according to Example 5 includes a coil element 20 embedded in a magnetic core 10 and an electrode member 30 connected to the coil element 20, and includes a coil element forming step (S10), an electrode member pre-forming step (S20), a connection step (S30), and a magnetic core forming step (S40). The coil element forming step (S10) forms a coil element 20 having a winding portion 21 and a lead portion 23 extending from an end of the winding portion 21. The electrode member pre-forming step (S20) forms an electrode member 30 having a side plate portion 35 arranged in a predetermined direction, a first lead portion 31 bent at one end of the side plate portion 35 in the predetermined direction, and a connection portion 34 extending from the first lead portion 31 and including, in order from closest to the first lead portion 31, a second crimping portion 34b and a first crimping portion 34a. The connection step (S30) connects the lead portion 23 to the connection portion 34. In the magnetic core forming step (S40), the coil element 20, the first lead portion 31, and the connection portion 34 are embedded in the magnetic core 10. In the connection step, the connection portion 34 between the first melting mark 34ma and the second melting mark 34mb and the lead portion 23 are melt-connected in the following procedure. That is, the lead portion 23 is sandwiched and crimped between the second crimping portion 34b and the first crimping portion 34a. Thereafter, a laser beam is irradiated onto the surface of the first crimping portion 34a in a direction from the surface side of the first crimping portion 34a toward the surface of the second crimping portion 34b, thereby forming a first melting mark 34ma on the surface of the first crimping portion 34a, which is a melting mark formed by melting and solidifying the first crimping portion 34a, and forming a second melting mark 34mb on the surface of the second crimping portion 34b, which is a melting mark formed by melting and solidifying the second crimping portion 34b. In this way, the connection portion 34 between the first fusion mark 34ma and the second fusion mark 34mb and the lead portion 23 are fusion-connected.

[0122] According to this manufacturing method, the inductor 1 described in Example 1 can be manufactured.

[0123] (Other Embodiments, etc.) While the inductor and the manufacturing method thereof according to the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments. As long as they do not deviate from the gist of the present disclosure, various modifications that a person skilled in the art can conceive of to the embodiments, as well as other forms constructed by combining some of the components of the embodiments, are also included in the scope of the present disclosure.

[0124] In the above embodiment, an example has been shown in which the connection portion 34 connected to the first lead portion 31 is joined to the lead portion 23, and the connection portion 44 connected to the first lead portion 41 is joined to the lead portion 24, but this is not limiting. For example, if a connection portion is provided in the second lead portion instead of the first lead portion, the connection portion connected to the second lead portion 32 may be joined to the lead portion 23, and the connection portion connected to the second lead portion 42 may be joined to the lead portion 24.

[0125] In the above embodiment, an example has been shown in which protrusions 33, 43 are provided and first crimping portion 34a is provided on the top surface 19 side of magnetic core 10, but this is not limiting. For example, first crimping portion 34a may be provided on the bottom surface 18 side of magnetic core 10 without providing protrusions 33, 43. In this case, laser light may be irradiated from the side that becomes bottom surface 18 of magnetic core 10 to melt and connect connection portion 34 and lead portion 23.

[0126] In the above embodiment, the conductor wire has a circular cross section, but is not limited thereto. The conductor wire may have a rectangular cross section. At least a portion of the lead portion may be flattened to facilitate connection to the electrode member.

[0127] The present disclosure also includes, for example, 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.

[0128] INDUSTRIAL APPLICABILITY The inductor according to the present disclosure is useful as an inductor used in various devices and equipment.

[0129] REFERENCE SIGNS LIST 1 inductor 10 magnetic core 10c center 10cL wire 10r corner 13, 14 end face 15, 16 side face 18 bottom face 18a bottom face recess 19 top face 20 coil element 21 winding portion 21c winding axis 23, 24 lead portion 30, 40 electrode member 31, 41 first lead portion 31g, 41g guide surface 32, 42 second lead portion 32h, 42h through hole 33, 43 protrusion 33e, 43e tip 34, 44 connection portion 34a first crimping portion 34b second crimping portion 34e, 44e edge 34m welded portion 34ma, 44ma first melting mark 34mb, 44mb second melting mark 35, 45 Side plate portion 35a, 45a End portion 35b, 45b End portion 36, 46 First groove portion 37, 47 Second groove portion 38, 48 Bottom plate portion 38a, 48a Leg portion 61 Support 62 Rotating member

Claims

1. A magnetic core having a bottom surface, a top surface facing away from the bottom surface, and an end surface connecting the bottom surface and the top surface; a coil element embedded in the magnetic core; and an electrode member connected to the coil element, wherein the coil element has a winding portion around which an insulating coated conductor is wound, and a lead portion drawn out from an end of the winding portion, and the electrode member has a side plate portion arranged along the end surface, a first lead portion extending from the end of the side plate portion on the top surface side into the magnetic core, and a connection portion connected to the first lead portion and including a second crimping portion and a first crimping portion in that order from closest to the first lead portion, the connection portion being crimped inside the magnetic core with the second crimping portion and the first crimping portion sandwiching the lead portion, and wherein the connection portion has a first melting mark formed on the surface of the first crimping portion where the first crimping portion melts and solidifies, An inductor having: a second melting mark formed on a surface of the second crimping portion, the second crimping portion being a melting mark formed by melting and solidifying the second crimping portion; and a welded portion between the first melting mark and the second melting mark, where the connection portion and the lead portion are melted and solidified.

2. The inductor according to claim 1, wherein the area of ​​the first melting mark is larger than the area of ​​the second melting mark.

3. The inductor according to claim 1 or 2, wherein the sum of the area of ​​the first melting mark and the area of ​​the second melting mark is 20% or more of the cross-sectional area of ​​the conductor wire.

4. An inductor according to claim 1 or 2, wherein the area average diameter of the crystalline structure of the welded portion is larger than the area average diameter of the portion other than the welded portion in the connection portion, the area average diameter of the crystalline structure of the welded portion is 5 μm or more and 100 μm or less, and the area average aspect ratio of the crystalline structure of the welded portion is 7 or less.

5. A method for manufacturing an inductor comprising a coil element embedded in a magnetic core and an electrode member connected to the coil element, comprising: a coil element forming step of forming the coil element having a winding portion and a lead portion drawn out from an end of the winding portion; an electrode member pre-forming step of forming an electrode member having a side plate portion arranged along a predetermined direction, a first lead portion bent at one end of the side plate portion in the predetermined direction, and a connection portion extending from the first lead portion and including a second crimping portion and a first crimping portion in that order closest to the first lead portion; a connecting step of connecting the lead portion and the connection portion; and a magnetic core forming step of embedding the coil element, the first lead portion, and the connection portion in the magnetic core, wherein in the connecting step, the lead portion is sandwiched and crimped between the second crimping portion and the first crimping portion, a first melting mark on the surface of the first crimped portion, the first melting mark being a melting mark caused by the first crimped portion melting and solidifying, and a second melting mark on the surface of the second crimped portion, the second melting mark being a melting mark caused by the second crimped portion melting and solidifying; and a method for manufacturing an inductor, the method comprising: irradiating a surface of the first crimped portion with laser light in a direction from the surface side of the first crimped portion toward the surface of the second crimped portion;

Images