Inductor

Abstract

The present invention improves the inspection quality of an inductor. This inductor (100) comprises: a three-dimensional magnetic core (10) that has a side surface (12); a coil element (20) that has an embedded part embedded in the magnetic core (10) and a coil end part (22) exposed from the magnetic core (10) and extending along the side surface (12); and an electrode member (30) that is welded to the coil end part (22). The electrode member (30) has a side plate (36) disposed along the side surface (12) of the magnetic core (10). The side plate (36) includes a side plate fixing part (36a) that is fixed to the side surface (12) of the magnetic core (10) and a side plate joining part (36b) that is welded to the coil end part (22). The outer surface (36f) of the side plate (36) is provided with a plated region (Tp) that has been subjected to solder plating and a non-plated region (Tn) that has not been subjected to solder plating. The side plate fixing part (36a) is provided with the plated region (Tp), and the side plate joining part (36b) is provided with the non-plated region (Tn).

Description

Inductor

[0001] The present disclosure relates to an inductor.

[0002] An inductor, which is a passive element that stores electrical energy as magnetic energy, is used in, for example, DC-DC converter devices and the like for the purpose of stepping up / down a power supply voltage and smoothing a direct current. As an example of such an inductor, Patent Documents 1 and 2 disclose a surface-mount inductor mounted on a circuit board. These inductors include a three-dimensional magnetic core containing a magnetic material, a coil element in which a winding portion of a coil is embedded in the magnetic core, and an electrode member joined to an end portion of the coil element protruding from a side surface of the magnetic core. These inductors are mounted on a circuit board by soldering the electrode members to the circuit board.

[0003] Japanese Unexamined Patent Application Publication No. 2011-249770 International Publication No. WO 2022 / 091761

[0004] In conventional inductors, there is room for improvement in inspection quality when inspecting mass-produced products. In view of the above, an object of the present disclosure is to provide an inductor capable of improving inspection quality.

[0005] An inductor according to one aspect of the present disclosure comprises a magnetic core, a coil element, and an electrode member. The magnetic core includes a magnetic material and has a three-dimensional shape with side surfaces, a bottom surface, and a top surface. The coil element includes a metallic material and has an embedded portion and a coil end. The embedded portion is embedded in the magnetic core. The coil end is exposed from the magnetic core and extends along the side surface. The electrode member includes a metallic material and is welded to the coil end. The electrode member has a side plate. The side plate is arranged along the side surface of the magnetic core. The side plate includes a side plate fixing portion and a side plate joint portion. The side plate fixing portion is fixed to the side surface of the magnetic core. The side plate joint portion is welded to the coil end. The outer surface of the side plate is provided with a plated area and an unplated area. The plated area is plated with tin or a tin-based solder plating. The unplated area is not plated with the solder plating. At least a portion of the side plate fixing portion is provided with the plated area. The side plate joint is provided with an unplated area, but without the plated area.

[0006] An inductor according to another aspect of the present disclosure comprises a magnetic core, a coil element, and an electrode member. The magnetic core comprises a magnetic material and has a three-dimensional shape having sides, a bottom, and a top. The coil element comprises a metallic material and has an embedded portion and a coil end. The embedded portion is embedded in the magnetic core. The coil end is exposed from the magnetic core and extends along the sides of the magnetic core. The electrode member comprises a metallic material and is welded to the coil end. A magnetic core recess is provided on the sides of the magnetic core. The magnetic core recess is recessed toward the interior of the magnetic core. The coil end protrudes from the magnetic core recess and extends along the inner bottom surface of the magnetic core recess. The electrode member is a copper-based metal foil with a thickness of less than 100 μm and comprises a side plate and a bottom plate. The side plate is arranged along the sides of the magnetic core. The bottom plate is arranged along the bottom surface of the magnetic core. The side plate has a side plate fixing portion, a side plate joining portion, and a side plate recess. The side plate fixing portion is fixed to the side surface of the magnetic core. The side plate joining portion is welded to the coil end. The side plate recess is connected to the side plate fixing portion and the side plate joining portion and is recessed in the direction of the inner bottom surface of the magnetic core recess. The outer surface of the side plate is provided with a plated area and an unplated area. The plated area is plated with tin or solder plating mainly composed of tin. The unplated area is not plated with solder plating. At least a portion of the side plate fixing portion and the side plate recess is provided with the plated area. The side plate joining portion is not provided with the plated area but is provided with the unplated area.

[0007] An inductor according to yet another aspect of the present disclosure comprises a magnetic core, a coil element, and an electrode member. The magnetic core comprises a magnetic material and has a three-dimensional shape having sides, a bottom, and a top. The coil element comprises a metallic material and has a recessed portion and a coil end. The recessed portion is embedded in the magnetic core. The coil end is exposed from the magnetic core and extends along the sides of the magnetic core. The electrode member comprises a metallic material and is welded to the coil end. A magnetic core recess is provided in the ridge connecting the sides and the top of the magnetic core, extending along the ridge and recessing toward the interior of the magnetic core. The coil end is housed in the magnetic core recess and extends in the direction in which the magnetic core recess extends. The electrode member comprises a side plate and a top plate. The side plate is arranged along the sides of the magnetic core and completely covers the side side of the magnetic core of the magnetic core recess. The top plate is arranged along the top surface of the magnetic core and completely covers the top side of the magnetic core of the magnetic core recess. The electrode member is welded to the coil end at a location where it directly faces and overlaps with the coil end. The side plate includes a side plate fixing portion and a side plate joining portion. The side plate fixing portion is fixed to the side surface of the magnetic core. The side plate joining portion is welded to the coil end. The outer surface of the side plate is provided with a plated area and an unplated area. The plated area is plated with tin or a solder plating mainly composed of tin. The unplated area is not plated with solder plating. At least a part of the side plate fixing portion is provided with the plated area. The side plate joining portion is not provided with the plated area but is provided with the unplated area.

[0008] The inductor of this disclosure can improve inspection quality.

[0009] Figure 1 is a perspective view of an inductor according to Embodiment 1. Figure 2 is a perspective view of the inductor shown in Figure 1 with its top and bottom reversed. Figure 3 is a perspective view of the magnetic core and coil element of the inductor shown in Figure 1. Figure 4 is a cross-sectional view of the magnetic core and coil element of the inductor taken along line IV-IV shown in Figure 3. Figure 5 is a view of the inductor according to Embodiment 1 from the top side. Figure 6 is a view of the inductor according to Embodiment 1 from the side side. Figure 7 is a cross-sectional view of the inductor taken along line VII-VII shown in Figure 1. Figure 8 is a cross-sectional view of the inductor taken along line VIII-VIII shown in Figure 7. Figure 9 shows the first corner portion provided on the side surface of the magnetic core of the inductor, and the second corner portion provided at the coil end of the coil element. Figure 10 shows the first and second bend portions provided on the side plate of the electrode member of the inductor. Figure 11 shows an image of a copper foil sample 1 that has not been plated or heat-treated, laser-welded to the coil end. Figure 12 shows an image of a copper foil sample 2 that has been plated and heat-treated, laser-welded to the end of a coil. Figure 13 shows an image of a copper foil sample 3 that has not been plated and heat-treated, laser-welded to the end of a coil. Figure 14 is a flowchart showing the manufacturing method of an inductor according to Embodiment 1. Figure 15 shows the form of the inductor during the manufacturing process according to Embodiment 1. Figure 16 is a schematic diagram showing various processes applied to the side plate of the electrode member of the inductor according to Embodiment 1. Figure 17 is a perspective view of an inductor according to Embodiment 2. Figure 18 is a perspective view showing the inductor shown in Figure 17 inverted vertically. Figure 19 is a perspective view showing the magnetic core and coil element of the inductor shown in Figure 17. Figure 20 is a cross-sectional view of the magnetic core and coil element of the inductor taken along the line XX-XX shown in Figure 19. Figure 21 is a view of the inductor according to Embodiment 2 from the top side. Figure 22 is a view of the inductor according to Embodiment 2 from the side side. Figure 23 is a flowchart showing the manufacturing method of an inductor according to Embodiment 2. Figure 24 shows the form of the inductor during the manufacturing process according to Embodiment 2.

[0010] (Background to this disclosure) In recent years, inductors have been used in many electronic devices. Inductors are sometimes mounted on circuit boards, and surface-mount type inductors designed for mounting on pads on circuit boards have also been developed.

[0011] Conventional inductors are known, for example, those described in Patent Document 1 or Patent Document 2. The inductor described in Patent Document 1 comprises a magnetic core formed of a magnetic material, a coil embedded inside the magnetic core with its terminal portion protruding from the side surface of the magnetic core, and a flat terminal protruding from the side surface of the magnetic core to the outside of the magnetic core and connected to the terminal portion of the coil. The terminal portion of the coil protruding from the side surface of the magnetic core and the flat terminal are bent along the side surface of the magnetic core toward the bottom surface of the magnetic core. The terminal portion of the coil is positioned between the flat terminal and the magnetic core.

[0012] Furthermore, the inductor described in Patent Document 2 comprises a magnetic core having a three-dimensional shape with a bottom surface, side surfaces and a top surface, a coil element having an embedded portion embedded in the magnetic core and a coil end exposed from the magnetic core and extending along the side surface, and an electrode member positioned on the opposite side from the magnetic core with the coil end in between, and having a plating layer on its surface. The electrode member has a side portion that partially overlaps the coil end, and the electrode member and the magnetic core are bonded together via an adhesive layer. The electrode member and the coil end are welded together in at least a portion of the area where the side portion and the coil end overlap.

[0013] However, in the inductor shown in Patent Document 1, a portion of the flat terminal is embedded in the magnetic core and fixed to the magnetic core body, and there is a gap between the magnetic core body and the flat terminal. Therefore, when vibration is applied, shaking occurs, which leads to a problem of reduced vibration resistance.

[0014] To solve this problem, Patent Document 2 discloses an inductor in which an electrode member is bonded to a magnetic core. With this inductor, when the inductor is mounted on a circuit board, the magnetic core and the electrode member behave as a single unit. Therefore, when vibrations are applied, stress concentration in each part between the electrode member fixed to the circuit board and the magnetic core and coil ends of the inductor is mitigated, making it possible to improve vibration resistance.

[0015] However, the inductor disclosed in Patent Document 2 has room for improvement in terms of inspection quality when inspecting mass-produced products. Therefore, in view of the above, this disclosure provides an inductor that can improve inspection quality. The embodiments will be described in more detail below with reference to the drawings.

[0016] The embodiments described below are all specific examples of this disclosure. The numerical values, shapes, materials, components, arrangement positions of components, connection configurations, steps, and step order shown in the following embodiments are examples only and are not intended to limit this disclosure. Furthermore, any components in the following embodiments that are not described in an independent claim will be described as optional components.

[0017] Furthermore, each figure shows the X, Y, and Z axes, which represent three mutually orthogonal directions, and these axes and the axial directions along them are used for explanatory purposes as needed. Note that these axes are included for explanatory purposes only and do not limit the direction or orientation in which the inductor is used.

[0018] (Embodiment 1) [Configuration] The inductor 100 according to Embodiment 1 will be described with reference to Figures 1 to 13.

[0019] Figure 1 is a perspective view of the inductor 100 according to Embodiment 1. Figure 2 is a perspective view of the inductor 100 shown in Figure 1, but inverted. Figure 3 is a perspective view of the magnetic core 10 and coil element 20 of the inductor 100 shown in Figure 1. Figure 4 is a cross-sectional view of the magnetic core 10 and coil element 20 of the inductor 100 taken along the line IV-IV shown in Figure 3. Figure 5 is a view of the inductor 100 according to Embodiment 1 from the top surface 14 side. Figure 6 is a view of the inductor 100 according to Embodiment 1 from the side surface 12 side.

[0020] In Figures 1, 2, and 6, the plated area Tp is indicated by hatched dots. Figure 3 shows the inductor 100 with the electrode member 30 removed. In Figure 4, the hatching of the magnetic core 10 is omitted.

[0021] As shown in Figures 1 and 2, the inductor 100 according to Embodiment 1 comprises a magnetic core 10, a coil element 20, and an electrode member 30.

[0022] The inductor 100, for example, has a rectangular parallelepiped-shaped powdered magnetic core, and its approximate outer shape is determined by the shape of the magnetic core 10. The magnetic core 10 can be formed into any shape by molding. In other words, an inductor 100 of any shape can be realized depending on the shape of the magnetic core 10 during molding. The inductor 100 of this embodiment is constructed using a magnetic core 10 with dimensions of 4 mm or more and 12 mm or less in the X-axis direction, 4 mm or more and 12 mm or less in the Y-axis direction, and 2 mm or more and 8 mm or less in the Z-axis direction.

[0023] The magnetic core 10 is the outer shell portion of the inductor 100 and covers a part of the coil element 20. The magnetic core 10 is, for example, a compacted magnetic core made of metallic magnetic powder and resin material. The magnetic core 10 can be formed using any magnetic material, such as ferrite, or other materials. For the metallic magnetic powder, particulate materials having a predetermined elemental composition such as Fe-Si-Al, Fe-Si, Fe-Si-Cr, or Fe-Si-Cr-B are used. For the resin material, a material such as silicone is selected that can maintain a certain shape by insulating the particles of the metallic magnetic powder while binding them together.

[0024] The magnetic core 10 is, for example, a rectangular parallelepiped, and has a base surface 13, four sides connected to the base surface 13, and a top surface 14 connected to the four sides and facing away from the base surface 13. The four sides are composed of two sides 11 facing away from each other in the X-axis direction and two sides 12 facing away from each other in the Y-axis direction. Each of the four sides 11 and 12 has a flat surface perpendicular to the base surface 13.

[0025] As shown in Figures 1 to 5, a magnetic core recess 12b is formed on the side surface 12, which is recessed toward the interior of the magnetic core 10. In other words, the side surface 12 is provided with a magnetic core recess 12b formed on the side surface 12 and a base portion 12a, which is the part of the side surface 12 excluding the magnetic core recess 12b. The base portion 12a is a flat portion along the side surface 12. The magnetic core recess 12b is the portion that extends into the interior of the magnetic core 10 when viewed from the base portion 12a. The magnetic core recess 12b may have a groove-like shape, or it may have a stepped shape that drops into the interior of the magnetic core 10 starting from the base portion 12a.

[0026] Figure 7 is a cross-sectional view of the inductor 100 along the line VII-VII shown in Figure 1.

[0027] As shown in Figure 7, the magnetic core recess 12b has an inner bottom surface 12b1 which is the inner bottom of the magnetic core recess 12b, and an inner wall surface 12b2 which connects the base 12a and the inner bottom surface 12b1. The inner bottom surface 12b1 is parallel to the side surface 12 of the magnetic core 10. The inner wall surface 12b2 has an inclined surface that is inclined with respect to the inner bottom surface 12b1 and the base 12a. The magnetic core recess 12b tapers towards the inner bottom surface 12b1 in the direction from the side surface 12 to the inner bottom surface 12b1. In other words, the opening of the magnetic core recess 12b widens as it moves from the inner bottom surface 12b1 toward the side surface 12.

[0028] As shown in Figures 3 and 4, the magnetic core recess 12b extends toward the top surface 14 and reaches the top surface 14, and opens toward the top surface 14. In this embodiment, the magnetic core recess 12b is composed of one inner bottom surface 12b1 and three inner wall surfaces 12b2. The direction in which the magnetic core recess 12b extends toward the top surface 14 is the same direction as the mold removal direction after the magnetic core 10 has been formed. The coil end 22 of the coil element 20 is located inside the magnetic core recess 12b.

[0029] As shown in Figures 4 and 5, the coil element 20 has an embedded portion 21 embedded in the magnetic core 10 and a plurality of coil ends 22 connected to the embedded portion 21. The coil element 20 of this embodiment is composed of one embedded portion 21 and two coil ends 22. The coil element 20 is made of a material selected from metallic materials such as aluminum, copper, silver, and gold, as well as alloys made of metal and other substances. The embedded portion 21 and the coil ends 22 are names given to the respective parts formed by processing a single member made of the same material.

[0030] The coil end 22 is a portion that is not covered by the magnetic core 10 and is exposed from the magnetic core recess 12b. The coil end 22 is flat and has a predetermined thickness. The thickness of the coil end 22 is, for example, 100 μm or more and 150 μm or less. The coil end 22 extends along the side surface 12 to the top surface 14 (i.e., along the Z-axis direction) (see Figures 3 and 4). Specifically, the coil end 22 protrudes from the magnetic core recess 12b and extends along the inner bottom surface 12b1 of the magnetic core recess 12b, and is interrupted before reaching the top surface 14. In other words, the coil end 22 is positioned in the magnetic core recess 12b so as not to protrude beyond the top surface 14 from the magnetic core recess 12b in the positive Z-axis direction.

[0031] As shown in Figure 7, the coil end 22 has an outer end surface 22f1 that contacts the side plate joint 36b, which will be described later, an inner end surface 22f2 that faces away from the outer end surface 22f1 and faces the inner bottom surface 12b1 of the magnetic core recess 12b, and an outer end surface 22s that connects to the outer end surface 22f1 and the inner end surface 22f2, respectively. The coil end 22 may be in contact with the inner bottom surface 12b1 of the magnetic core recess 12b, or it may be positioned with a gap between it and the inner bottom surface 12b1.

[0032] The buried portion 21 shown in Figures 4 and 5 is the part covered by the magnetic core 10. The buried portion 21 is made by winding a long piece of material and functions as a coil. There are no particular limitations on the number of turns of the buried portion 21; for example, 0.5 turns, 10 turns, or 100 turns can be appropriately selected according to the performance required of the inductor 100 and constraints such as the size of the magnetic core 10. The buried portion 21 is formed, for example, by bending a copper wire covered with an insulating coating. The cross-section of the copper wire constituting the buried portion 21 is, for example, circular with a diameter in the range of 0.16 mm to 1.40 mm. The cross-section (transverse surface) of the copper wire may be other than circular, for example, elliptical or rectangular. In the case of a rectangle, the aspect ratio of the cross-section (transverse surface) of the copper wire may be 1:1.

[0033] The buried portion 21 is positioned such that the wound winding shaft is aligned with the Z-axis direction. The buried portion 21 has a curved portion formed by winding and a straight portion connecting the curved portion and the coil end 22. The straight portion of the buried portion 21 extends in the Y-axis direction toward the side surface 12 of the magnetic core 10 where the coil end 22 is located and is connected to the coil end 22.

[0034] The electrode member 30 shown in Figures 1 and 2 has a side plate 36 and a bottom plate 34. The side plate 36 and the bottom plate 34 are formed by bending metal foil, which is the material of the electrode member 30.

[0035] The electrode member 30 is made of a copper-based metal material, including copper or a copper alloy. For example, in the inductor 100 in this embodiment, a copper electrode member 30 is selected.

[0036] The electrode member 30 is made of a flexible material, for example, a foil material having a thickness of 20 μm or more and less than 100 μm. The thickness of the electrode member 30 is thinner than the thickness of the coil end 22, and in this embodiment, the thickness of the electrode member 30 is 50 μm. The flexibility of the electrode member 30 allows it to be bent to follow the surface of the coil end 22 and the magnetic core 10. The flexibility of the electrode member 30 means that when the electrode member 30 is pressed against the magnetic core 10 and the coil end 22, it has the property of being able to plastically deform in accordance with the surface shape of the magnetic core 10 and the coil end 22. In other words, the electrode member 30 deforms when subjected to an external force and maintains its shape after deformation.

[0037] The electrode members 30 are provided one at each of the two coil ends 22, in each direction along the Y-axis of the inductor 100. Here, we will describe one of the two electrode members 30, but the same description applies to the other electrode member 30 as they have the same configuration. The side plate 36 and bottom plate 34 of the electrode member 30 are names given to the respective parts, which are formed by processing a single member made of the same material.

[0038] The side plates 36 shown in Figures 5 and 6 are parts provided to correspond to the side surface 12 of the magnetic core 10 and to be positioned along the side surface 12. The side plates 36 are positioned to overlap the base 12a and coil end 22 of the side surface 12 of the magnetic core 10. The bottom plate 34 is a part provided to correspond to the bottom surface 13 of the magnetic core 10 and to be positioned along the bottom surface 13. The bottom plate 34 is positioned to overlap a part of the bottom surface 13 of the magnetic core 10.

[0039] The side plate 36 is provided with solder plating. This solder plating is the part that will be soldered when the inductor 100 is mounted on the circuit board (not shown). The configuration of the solder plating will be explained in detail later.

[0040] The side plate 36 has a side plate fixing portion 36a, a side plate joining portion 36b, and a side plate recess 36c.

[0041] The side plate fixing portion 36a is a part that is fixed to the side surface 12 of the magnetic core 10. When viewed from a direction perpendicular to the side surface 12, the side plate fixing portion 36a overlaps the base portion 12a and is fixed to the base portion 12a via an adhesive. The adhesive is a thermosetting adhesive that undergoes a curing reaction with heat, for example, an epoxy resin-based adhesive or a silicone resin-based adhesive. The thermosetting temperature of the adhesive is, for example, 150°C or higher.

[0042] The side plate joint 36b is the part that is welded to the coil end 22. When viewed from a direction perpendicular to the side surface 12, the side plate joint 36b has an overlapping region Ts that overlaps with the coil end 22. The side plate joint 36b is welded to the coil end 22 by laser processing. In other words, a welded portion 40 is formed at the side plate joint 36b and the coil end 22 to connect the side plate 36 and the coil end 22. The welded portion 40 is formed, for example, by irradiating the side plate joint 36b and the coil end 22 with laser light, such as a CW (Continuous Wave) laser. The shape of the welded portion 40 may be spot-shaped or strip-shaped.

[0043] The side plate recess 36c is connected to the side plate fixing portion 36a and the side plate joining portion 36b, and is a recessed portion that, when viewed from the side surface 12 of the magnetic core 10, is in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b. The side plate 36 has two side plate recesses 36c, and the two side plate recesses 36c are located on both sides of the coil end 22 when viewed from a direction perpendicular to the side surface 12 of the magnetic core 10. The side plate recess 36c is positioned between the inner wall surface 12b2 of the magnetic core recess 12b and the coil end 22. Furthermore, the side plate recess 36c has a shape that conforms to the shape of the outer surface of the magnetic core recess 12b and the coil end 22. For example, the side plate recess 36c is formed by applying a pressing jig 80 (see Figure 16(d), described later) to a part of the side plate 36 between the side plate fixing part 36a and the side plate joining part 36b, and pushing a part of the side plate 36 toward the inner bottom surface 12b1 of the magnetic core recess 12b.

[0044] The side plate recess 36c formed by the pressing jig 80 includes, as shown in Fig. 7, an inner bottom portion 36c1 located at the inner bottom of the side plate recess 36c, and an inner wall portion 36c2 connecting the side plate fixing portion 36a and the inner bottom portion 36c1. The inner bottom portion 36c1 of the side plate recess 36c is substantially parallel to the side surface 12 of the magnetic core 10, and is located closer to the inner bottom surface 12b1 of the magnetic core recess 12b than the side surface 12 and the outer end surface 22f1 of the coil end portion 22. The inner wall portion 36c2 has an inclined surface that is inclined relative to the inner bottom portion 36c1 and the side plate fixing portion 36a. The side plate recess 36c is tapered in a direction from the side plate fixing portion 36a toward the inner bottom portion 36c1. The inclination angle of the inner wall portion 36c2 based on the inner bottom portion 36c1 is smaller than the inclination angle of the inner wall surface 12b2 based on the inner bottom surface 12b1.

[0045] For example, the depth dp2 of the side plate recess 36c is not less than 0.3 times and not more than 0.9 times the depth dp1 of the magnetic core recess 12b. The side plate recess 36c is not in contact with the inner bottom surface 12b1 of the magnetic core recess 12b, and a predetermined gap is provided between the side plate recess 36c and the inner bottom surface 12b1 of the magnetic core recess 12b. The side plate recess 36c is formed by bending deformation caused by pressing of the pressing jig 80. In order to maintain the shape after deformation, the depth dp2 of the side plate recess 36c is preferably not less than 1 / 2 of the thickness of the electrode member 30.

[0046] Fig. 8 is a cross-sectional view of the inductor 100 taken along line VIII-VIII shown in Fig. 7. Fig. 9 is a diagram showing a first corner portion m1 provided on the side surface 12 of the magnetic core 10 of the inductor 100, and a second corner portion m2 provided on the coil end portion 22 of the coil element 20. Fig. 10 is a diagram showing a first bent portion n1 and a second bent portion n2 provided on the side plate 36 of the electrode member 30 of the inductor 100.

[0047] As shown in FIGS. 7 to 9, the magnetic core 10 has a plurality of first corner portions m1 located at the boundary between the side surface 12 of the magnetic core 10 and the inner wall surface 12b2 of the magnetic core recess 12b. The first corner portion m1 is a portion serving as a starting point of a step formed by the base portion 12a and the inner wall surface 12b2. The corner portion of the first corner portion m1 may be rounded. When viewed from a direction perpendicular to the side surface 12 of the magnetic core 10, the plurality of first corner portions m1 are formed along the inner wall surface 12b2 of the magnetic core recess 12b (see FIG. 9). Among the plurality of first corner portions m1, two first corner portions m1 are formed along a direction that is along the side surface 12 and parallel to an axis perpendicular to the bottom surface 13 and the top surface 14. The other two first corner portions m1 are formed along a direction that is along the side surface 12 and parallel to the bottom surface 13.

[0048] As shown in FIGS. 7 and 9, the coil end portion 22 has two second corner portions m2 located at the boundary between the outer end surface 22f1 and the side end surface 22s. The second corner portion m2 is a corner portion formed by the outer end surface 22f1 and the side end surface 22s. The corner portion of the second corner portion m2 has a predetermined roundness. The second corner portion m2 is formed along the extending direction of the coil end portion 22.

[0049] As shown in FIGS. 7 and 10, the side plate 36 of the electrode member 30 has a first bent portion n1 located at the boundary between the side plate fixing portion 36a and the side plate recess 36c, and a second bent portion n2 located at the boundary between the side plate joining portion 36b and the side plate recess 36c. The first bent portion n1 and the second bent portion n2 are simultaneously formed when the side plate recess 36c is formed by pressing a pressing jig 80 into a part of the side plate 36.

[0050] The first bent portion n1 is in contact with the first corner portion m1 so as to cover the first corner portion m1. The first bent portion n1 may be in contact with the first corner portion m1 via an adhesive. The side plate recess 36c is recessed starting from the first bent portion n1 toward the inner bottom surface 12b1 of the magnetic core recess 12b.

[0051] The second bent portion n2 is in contact with the second corner portion m2 so as to cover the second corner portion m2. The second bent portion n2 is in contact with the second corner portion m2. The side plate recess 36c is recessed starting from the second bent portion n2 toward the inner bottom surface 12b1 of the magnetic core recess 12b.

[0052] The two first corners m1 shown in Figure 7 are arranged in a direction along the side surface 12 of the magnetic core 10 and parallel to the bottom surface 13 of the magnetic core 10, that is, in a direction along the X-axis. The two first bent portions n1 are each located diagonally inward from the two first corners m1 and are in contact with the two first corners m1 located diagonally outward from the two first bent portions n1. This arrangement of the two first corners m1 and the two first bent portions n1 restricts the position of the magnetic core 10 with respect to the electrode member 30 in the X-axis direction. As a result, the vibration resistance of the inductor 100 is improved.

[0053] Furthermore, the two second corner portions m2 shown in Figure 7 are arranged in a direction along the outer surface 22f1 of the end and perpendicular to the extension direction of the coil end portion 22, that is, in a direction along the X-axis. The two second bent portions n2 are each located diagonally outside the two second corner portions m2 and are in contact with the two second corner portions m2 located diagonally inside the two second bent portions n2. This arrangement of the two second corner portions m2 and the two second bent portions n2 restricts the position of the coil end portion 22 relative to the electrode member 30 in the X-axis direction. As a result, the vibration resistance of the inductor 100 is improved.

[0054] The first corner portion m1 shown in Figure 8 is located near the bottom surface 13 of the magnetic core recess 12b in a direction perpendicular to the bottom surface 13 and top surface 14 of the magnetic core 10, i.e., in the Z-axis direction. The bottom plate 34 of the electrode member 30 is in contact with the bottom surface 13 of the magnetic core 10. The first bent portion n1 and the bottom plate 34 are located outside the first corner portion m1 and the bottom surface 13, respectively, and are in contact with the first corner portion m1 and the bottom surface 13 of the magnetic core 10, respectively. This arrangement of the first corner portion m1, the first bent portion n1, the bottom surface 13 of the magnetic core 10, and the bottom plate 34 of the electrode member 30 restricts the position of the magnetic core 10 relative to the electrode member 30 in the Z-axis direction. This improves the vibration resistance of the inductor 100.

[0055] Furthermore, the position of the magnetic core 10 in the Y-axis direction is restricted by the fact that the two electrode members 30, when joined to the circuit board, contact the two sides 12 of the magnetic core 10. This ensures the vibration resistance of the inductor 100.

[0056] In this embodiment, a plating layer made of solder plating is formed on both the side plate 36 and the bottom plate 34. The solder plating is tin or a plating mainly composed of tin. The plating region Tp, which is the area where the solder plating is provided, is formed on a part of the outer surface 36f of the side plate 36 and on the entire outer surface 34f of the bottom plate 34. The outer surface 36f of the side plate 36 is the surface located opposite the magnetic core 10 when viewed from the side plate 36, and the outer surface 34f of the bottom plate 34 is the surface located opposite the magnetic core 10 when viewed from the bottom plate 34.

[0057] The following describes the configuration of the solder plating provided on the outer surface 36f of the side plate 36. As shown in Figure 6, the outer surface 36f of the side plate 36 is provided with a plated area Tp where solder plating is applied, and an unplated area Tn where solder plating is not applied. In Figure 6, the plated area Tp is indicated by the area of ​​hatched dots, and the unplated area Tn is indicated by the area without hatching.

[0058] A plated area Tp is provided in at least a portion of the side plate fixing portion 36a. In this example, more than 80% of the outer surface 36f of the side plate fixing portion 36a is the plated area Tp, and the portion excluding the plated area Tp is the unplated area Tn. The plated area Tp is provided on both outer sides of the unplated area Tn when viewed from a direction perpendicular to the side surface 12. The plated area Tp is also provided in the area extending from the unplated area Tn toward the bottom surface 13. Of the side plate fixing portion 36a, the plated area Tp located from the lower end of the unplated area Tn to the bottom surface 13 is the area where the solder material gets wet when the inductor 100 is soldered to the circuit board.

[0059] The side plate joint 36b does not have a plated area Tp, but it does have an unplated area Tn. For example, the unplated area Tn is formed by forming a plating on the entire surface of one main surface of the copper foil that will become the electrode member 30 before bonding the electrode member 30 to the magnetic core 10, and then irradiating this entire plating with a pulsed laser to remove a portion of the plating. The unplated area Tn is rectangular when viewed from a direction perpendicular to the side surface 12. The unplated area Tn is formed in the side plate joint 36b, the inner wall portion 36c2 of the side plate recess 36c that is connected to the side plate joint 36b, and a part of the side plate fixing portion 36a that is connected to the lower end of the side plate joint 36b. The aforementioned welded portion 40 is formed in the unplated area Tn.

[0060] As shown in Figure 6, the width direction dw is defined as the direction along the side surface 12 of the magnetic core 10 and parallel to the bottom surface 13. When comparing the dimensions in this width direction dw, the width wn of the unplated area Tn is greater than or equal to the width ws of the overlapping area Ts of the side plate joint 36b (wn ≥ ws). For example, the width wn of the unplated area Tn is at least 1 times and not exceeding 4 times the width ws of the overlapping area Ts. Furthermore, when comparing the lengths in the direction perpendicular to the bottom surface 13 of the magnetic core 10 (height direction dh), the length Ln of the unplated area Tn is greater than or equal to the length Ls of the overlapping area Ts (Ln ≥ Ls). For example, the length Ln of the unplated area Tn is at least 1 times and not exceeding 2 times the length Ls of the overlapping area Ts. Note that the length Ln of the unplated area Tn may also be at least 1 time and not exceeding 4 times the length Ls of the overlapping area Ts.

[0061] The unplated area Tn is not plated and the copper material is originally exposed, making the surface prone to oxidation. In this example, when the adhesive is cured, heat treatment is performed at a temperature of 150°C or higher in an atmospheric environment, so the unplated area Tn becomes oxidized, i.e., an oxide film is formed. In addition, the surface of the exposed copper material in the unplated area Tn discolors and darkens due to oxidation. When the welded area 40 is formed by laser processing, the copper material melts and solidifies in the area where the welded area 40 is formed, so the oxide film is hardly visible. However, in the unplated area Tn excluding the welded area 40, the metal material (copper material) of the electrode member 30 is oxidized and darkened. For example, the area of ​​the unplated area Tn excluding the welded area 40 has a lower surface brightness than the welded area 40 and the plated area Tp. Brightness indicates the degree of lightness of a color; the brighter the color, the higher the brightness, and the darker the color, the lower the brightness.

[0062] For example, when a coil end 22 and an electrode member 30 are overlapped and welded by laser processing, and the welded part 40 is visually inspected using a camera, it is difficult to determine the quality of the welded part 40 if the difference in brightness between the welded part 40 and the surrounding material is small. Also, if the area around the welded part 40 is made of a material that reflects light, such as plating, it is difficult to determine the quality of the welded part 40.

[0063] Here, we will explain the differences in the appearance of the welded area depending on whether the copper foil sample is plated or heat-treated. Note that the material of the copper foil sample shown below is the same as the material of the electrode member 30. The welded area 40 is formed by scanning a laser beam from the coil end 22 toward the bottom surface 13, and melting and solidifying a portion of the copper foil sample and the coil end 22 in the area where the coil end 22 and the copper foil sample overlap.

[0064] Figure 11 shows an image of a copper foil sample 1 that has not been plated or heat-treated, after being laser-welded to the coil end 22. As shown in Figure 11, in the copper foil sample 1 that has not been plated or heat-treated, it is difficult to distinguish the color of the welded area formed by laser processing from the surrounding copper material, making it difficult to visually inspect the welded area.

[0065] Figure 12 shows an image of a copper foil sample 2 that has been plated and heat-treated, after being laser-welded to the coil end 22. As shown in Figure 12, in the plated and heat-treated copper foil sample 2, it is difficult to distinguish between the welded portion formed by laser processing and the plating surrounding the welded portion, making it difficult to visually inspect the welded portion.

[0066] Figure 13 shows an image of a copper foil sample 3 that has not been plated and has been heat-treated, after being laser-welded to the coil end 22. As shown in Figure 13, in the copper foil sample 3 that has not been plated and has been heat-treated, it is easy to distinguish between the surface of the welded portion formed by laser processing and the surface of the copper material surrounding the welded portion that has oxidized and turned black.

[0067] The combination of the copper foil sample 3 and the coil end 22 shown in Figure 13 is the same as in the embodiment. In this embodiment, by oxidizing the surface of the copper material by heat treatment without plating, the brightness of the area excluding the welded portion is made lower than the brightness of the welded portion and the plated area Tp, respectively. Therefore, the difference in brightness between the welded portion and the surrounding area can be made large. This allows for accurate judgment of quality during visual inspection and improves inspection quality.

[0068] The inductor 100 of this embodiment comprises a magnetic core 10, a coil element 20, and an electrode member 30. The magnetic core 10 contains a magnetic material and has a three-dimensional shape with a side surface 12, a bottom surface 13, and a top surface 14. The coil element 20 contains a metal material and has an embedded portion 21 and a coil end 22. The embedded portion 21 is embedded in the magnetic core 10. The coil end 22 is exposed from the magnetic core 10 and extends along the side surface 12. The electrode member 30 contains a metal material and is welded to the coil end 22. The electrode member 30 has a side plate 36. The side plate 36 is arranged along the side surface 12 of the magnetic core 10. The side plate 36 includes a side plate fixing portion 36a and a side plate joining portion 36b. The side plate fixing portion 36a is fixed to the side surface 12 of the magnetic core 10. The side plate joining portion 36b is welded to the coil end 22. The outer surface 36f of the side plate 36 is provided with a plated area Tp and an unplated area Tn. The plated area Tp is plated with tin or solder plating mainly composed of tin. The unplated area Tn is not plated with solder plating. At least a part of the side plate fixing portion 36a is provided with a plated area Tp. The side plate joining portion 36b is not provided with a plated area Tp but is provided with an unplated area Tn.

[0069] In this way, by providing an unplated area Tn in the side plate joint 36b, the unplated area Tn can be oxidized when, for example, the adhesive used to bond the electrode member 30 and the magnetic core 10 is heat-treated and heat-cured. As a result, the difference in brightness between the welded area and the unplated area Tn surrounding the welded area can be increased. This allows for accurate judgment of quality during visual inspection and improves the inspection quality of the inductor 100.

[0070] [Manufacturing Method] Next, the manufacturing method of the inductor 100 described above will be explained with reference to Figures 14 to 16.

[0071] Figure 14 is a flowchart showing the manufacturing method of the inductor 100 according to Embodiment 1. Figure 15 is a diagram showing the configuration during the manufacturing process of the inductor 100 according to Embodiment 1. Figure 16 is a schematic diagram showing various processes applied to the side plate 36 of the electrode member 30 of the inductor 100 according to Embodiment 1.

[0072] In the manufacturing method of the inductor 100, first, as shown in Figure 15(a), the coil element 20 is formed by winding a wire (step S101). This forms a coil element 20 having a winding portion and an end.

[0073] Next, as shown in Figure 15(b), the magnetic core 10 is molded by pressure molding (step S102). This molding of the magnetic core 10 is carried out by pressure molding the compacted magnetic core so as to enclose the winding portion of the coil element 20. Magnetic core recesses 12b are formed on the two sides 12 of the magnetic core 10. After step S102, the insulating coating on the ends of the coil element 20 protruding from the magnetic core recesses 12b is removed.

[0074] Next, as shown in Figure 15(c), the ends of the coil element 20 are press-formed into a flat plate shape (step S103).

[0075] Next, as shown in Figure 15(d), a step (step S104) is performed in which the end of the coil element 20 is bent along the side surface 12 of the magnetic core 10. This bending step positions the coil end 22 within the magnetic core recess 12b (see Figure 16(a)).

[0076] Next, as shown in Figure 15(e), adhesive is applied to the two sides 12 of the magnetic core 10 (step S105). The adhesive is formed on the base 12a of the magnetic core 10 by, for example, printing or application with a dispenser (see Figure 16(b)).

[0077] Next, as shown in Figure 15(f), electrode members 30 are attached to each of the two sides 12 of the magnetic core 10 (step S106). The plated area Tp is formed by plating a strip of copper foil with a solder plating material. The unplated area Tn is formed by irradiating the coated plating material with a pulsed laser to remove a portion of the plating material. Then, the plate-shaped electrode member 30 is formed by punching out the copper foil on which the plated area Tp and the unplated area Tn are formed.

[0078] In step S106, the electrode member 30, which has been pre-bent and formed to have side plates 36 and a bottom plate 34, is attached to the side surface 12 and bottom surface 13 of the magnetic core 10. When attaching the electrode member 30 to the magnetic core 10, it may also be attached by pressing the side plates 36 and bottom plate 34 of the electrode member 30 against the side surface 12 and bottom surface 13 of the magnetic core 10 using a jig (not shown).

[0079] After attaching the electrode members 30, the adhesive is cured by heat treatment at 150°C or higher in an atmospheric environment, thereby fixing the side plates 36 of the electrode members 30 to the respective side surfaces 12 of the magnetic core 10 (see Figure 16(c)). Due to this heat treatment, the surface of the copper material exposed in the unplated region Tn oxidizes and darkens. However, the surface of the solder plating in the plated region Tp does not darken even when oxidized.

[0080] Next, as shown in Figure 15(g), a side plate recess 36c is formed in the side plate 36 (step S107). The side plate recess 36c is formed by applying a pressing jig 80 to a part of the side plate 36 between the side plate fixing part 36a and the side plate joining part 36b, and pushing the part of the side plate 36 toward the inner bottom surface 12b1 of the magnetic core recess 12b (see Figure 16(d)). This pressing by the pressing jig 80 bends and stretches a part of the side plate 36, forming the inner bottom part 36c1, the inner wall part 36c2, and the first bent part n1 and the second bent part n2 of the side plate recess 36c. The formation of this side plate recess 36c is achieved by a type of drawing process in which the pressing jig 80 is used as a punch and the magnetic core 10 including the magnetic core recess 12b is used as a die. The two side plate recesses 36c located on both sides of the coil end 22 are formed simultaneously by the pressing jig 80. The side plate recesses 36c of each of the two electrode members 30 may be formed simultaneously by two pressing jigs 80 positioned on both outer sides of the side surface 12 of the magnetic core 10.

[0081] Next, as shown in Figure 15(h), a step (step S108) is performed in which the electrode member 30 and the coil end 22 are welded together by lap joint laser welding. In the welding process, the coil end 22 and the electrode member 30 are laser welded together to form a welded joint 40. This laser processing welds the electrode member 30 to the coil end 22 (see Figure 16(e)).

[0082] Next, the inductor 100 manufactured in steps S101 to S108 is visually inspected. As described above, by not plating the side plate joint 36b and performing heat treatment to oxidize the surface of the copper material, the brightness around the welded part 40 can be made lower than the brightness of the welded part 40 and the brightness of the plated area Tp. This makes it possible to accurately determine whether the welded part 40 is good or bad by visual inspection, and improves the quality of the inspection.

[0083] The method for manufacturing the inductor 100 according to this embodiment includes an element formation step, a magnetic core formation step, a bending step, a fixing step, a recess formation step, and a welding step. In the element formation step, a coil element 20 having a winding portion and a coil end 22 is formed. In the magnetic core formation step, when forming a rectangular parallelepiped-shaped magnetic core 10 having a magnetic core recess 12b on its side surface 12, the winding portion is embedded so that the coil end 22 protrudes from the magnetic core recess 12b to form the magnetic core 10. In the bending step, the coil end 22 is bent so that the coil end 22 protruding from the magnetic core recess 12b is positioned within the magnetic core recess 12b. In the fixing step, the side plate 36 of the electrode member 30 is fixed to the side surface 12 of the magnetic core 10 so as to cover at least a portion of the coil end 22 positioned within the magnetic core recess 12b. In the recess formation step, a portion of the side plate 36 of the electrode member 30 is pushed into the magnetic core recess 12b to form a side plate recess 36c. In the welding process, the electrode member 30 is welded to the coil end 22.

[0084] In this embodiment, before the fixing process, a plated area Tp and an unplated area Tn are provided on the electrode member 30. In the fixing process, heat treatment is performed in an atmospheric environment to cure the adhesive, and this heat treatment oxidizes the unplated area Tn, causing the surface to darken. In the welding process, a welded area 40 is formed in the unplated area Tn by laser processing.

[0085] In this way, by not plating the side plate joint 36b and performing heat treatment to oxidize the surface of the copper material, the brightness around the welded area can be made lower than the brightness of the welded area and the brightness of the plated area Tp. This allows for accurate quality judgment of the welded area by visual inspection, thereby improving the inspection quality of the inductor 100.

[0086] (Embodiment 2) [Configuration] The inductor 100A according to Embodiment 2 will be described with reference to Figures 17 to 22.

[0087] Figure 17 is a perspective view of the inductor 100A according to Embodiment 2. Figure 18 is a perspective view of the inductor 100A shown in Figure 17 with its top and bottom reversed. Figure 19 is a perspective view of the magnetic core 10 and coil element 20 of the inductor 100A shown in Figure 17. Figure 20 is a cross-sectional view of the magnetic core 10 and coil element 20 of the inductor 100A taken along the line XX-XX shown in Figure 19. Figure 21 is a view of the inductor 100A according to Embodiment 2 from the top surface 14 side. Figure 22 is a view of the inductor 100A according to Embodiment 2 from the side surface 12 side.

[0088] In Figures 17, 18, and 22, the plated area Tp is indicated by hatched dots. Figure 19 shows the inductor 100A with the electrode member 30 removed. In Figure 20, the hatching of the magnetic core 10 is omitted.

[0089] As shown in Figures 17 and 18, the inductor 100A according to Embodiment 2 comprises a magnetic core 10, a coil element 20, and an electrode member 30.

[0090] Inductor 100A, for example, has a rectangular parallelepiped-shaped powdered magnetic core, and its approximate external shape is determined by the shape of the magnetic core 10. The magnetic core 10 can be formed into any shape by molding. In other words, inductors 100A of any shape can be realized depending on the shape of the magnetic core 10 during molding. The inductor 100A of this embodiment is composed of a magnetic core 10 that is relatively low-profile, with dimensions of 3 mm or more and 4 mm or less in the X-axis direction, 3 mm or more and 4 mm or less in the Y-axis direction, and 2 mm in the Z-axis direction. For example, inductor 100A may have dimensions of 4 mm in the X-axis direction, 4 mm in the Y-axis direction, and 2 mm in the Z-axis direction.

[0091] The magnetic core 10 is the outer shell portion of the inductor 100A and covers a part of the coil element 20. The magnetic core 10 is, for example, a compacted magnetic core made of metallic magnetic powder and resin material. The magnetic core 10 may be formed using any magnetic material, such as ferrite, or other materials. For the metallic magnetic powder, particulate materials having a predetermined elemental composition such as Fe-Si-Al, Fe-Si, Fe-Si-Cr, or Fe-Si-Cr-B are used. For the resin material, a material such as silicone is selected that can maintain a certain shape by insulating the particles of the metallic magnetic powder from each other and binding them together.

[0092] The magnetic core 10 is, for example, a rectangular parallelepiped, and has a base surface 13, four sides connected to the base surface 13, and a top surface 14 connected to the four sides and facing away from the base surface 13. The four sides are composed of two sides 11 facing away from each other in the X-axis direction and two sides 12 facing away from each other in the Y-axis direction. Each of the four sides 11 and 12 has a flat surface perpendicular to the base surface 13.

[0093] As shown in Figures 17, 19 to 21, a magnetic core recess 12b is formed at the ridge where the side surface 12 and the top surface 14 connect, indenting toward the interior of the magnetic core 10. In other words, the side surface 12 and the top surface 14 are provided with the magnetic core recess 12b formed on the side surface 12 and the top surface 14, and the portion excluding the magnetic core recess 12b. The portion excluding the magnetic core recess 12b is a flat portion along the side surface 12 and the top surface 14, respectively. The magnetic core recess 12b is the portion that extends into the interior of the magnetic core 10 when viewed from the portion of the side surface 12 and the top surface 14 excluding the magnetic core recess 12b. In other words, the magnetic core recess 12b can be said to be the portion that extends into the interior of the magnetic core 10 from the side surface 12, or the portion that extends into the interior of the magnetic core 10 from the top surface 14.

[0094] The magnetic core recess 12b has a groove-like shape for accommodating the coil end 22, which will be described later, and extends along the ridge of the ridge where the side surface 12 and the top surface 14 connect. However, both ends of the magnetic core recess 12b in the direction of extension (the direction connecting the side surfaces 11) are interrupted and do not connect to the side surfaces 11. Therefore, in a plan view from the side surface 12, the magnetic core recess 12b is pocket-shaped, having a bottom wall surface that extends approximately parallel to the top surface 14 and side wall surfaces closer to both side surfaces 11 (surrounded by these surfaces).

[0095] As shown in Figures 19 and 20, the magnetic core recess 12b reaches the side surface 12 and the top surface 14, respectively, and opens toward the side surface 12 and the top surface 14 of the magnetic core recess 12b. The coil end 22 of the coil element 20, which is arranged to extend along the extension direction of the magnetic core recess 12b, is housed inside the magnetic core recess 12b.

[0096] As shown in Figures 20 and 21, the coil element 20 has an embedded portion 21 embedded in the magnetic core 10 and a plurality of coil ends 22 connected to the embedded portion 21. The coil element 20 of this embodiment is composed of one embedded portion 21 and two coil ends 22. The coil element 20 is made of a material selected from metallic materials such as aluminum, copper, silver, and gold, as well as alloys made of metal and other substances. The embedded portion 21 and the coil ends 22 are designations given to the respective parts formed by processing a single member made of the same material.

[0097] The coil end 22 is a portion that is not covered by the magnetic core 10 and is exposed from the magnetic core recess 12b. The coil end 22 is rectangular in shape and extends within the magnetic core recess 12b along the side surface 12 and the top surface 14 (i.e., along the X-axis direction) (see Figures 19 and 20). Specifically, the coil end 22 protrudes from one end of the magnetic core recess 12b and extends along the direction in which the magnetic core recess 12b extends, and is terminated before reaching the other end of the magnetic core recess 12b. The coil end 22 does not protrude from the coil end 22 in the X-axis direction and is housed within the magnetic core recess 12b in its direction of extension. Furthermore, the magnetic core recess 12b is recessed inward toward the magnetic core 10 to a degree greater than the dimensions of the coil end 22 in order to completely house the coil end 22. As a result, the coil end 22 is positioned within the magnetic core recess 12b so as not to protrude from the magnetic core recess 12b in either the Y-axis direction or the Z-axis direction.

[0098] As shown in Figures 20 and 21, the coil end 22 has an exposed end portion 22a that is exposed from the magnetic core 10 to the outside of the magnetic core 10, an extruded end portion 22b that displaces the extension position of the coil end 22 in the height direction (Z-axis direction), and an end ridge portion 22c that extends along the ridge of the ridge portion of the side surface 12 and the top surface 14.

[0099] As shown in Figure 20, the exposed end portion 22a is exposed from the magnetic core 10 to the outside of the magnetic core 10 at a predetermined length (height H1) from the top surface 14. The height H1 is set to 10% or more of the length between the top surface 14 and the bottom surface 13 of the magnetic core 10 (i.e., height Hs). This makes it possible to provide a compacted magnetic core with a height of 10% or more of the height of the magnetic core 10 at least above the position of the exposed end portion 22a (closer to the top surface 14). For example, if the height H1 is less than 10% of the height Hs, the amount of compacted magnetic core provided above the position of the exposed end portion 22a will decrease, which may make it easier for cracks to occur when bending the coil end 22. Therefore, by setting the height H1 to 10% or more of the height Hs, such cracks are less likely to occur, and the yield of the inductor 100A is improved.

[0100] At a height of H1, the exposed end portion 22a that is exposed from the magnetic core recess 12b is connected to the end displacement portion 22b. The end displacement portion 22b is the part that provides a displacement in the height direction so that the extended position of the coil end 22 is closer to the top surface 14. In other words, the end displacement portion 22b is the part that extends in a direction that includes at least a component in the height direction (Z-axis direction). Due to the end displacement portion 22b, the coil end 22 is displaced to a position where its length from the top surface 14 is less than 10% of the height Hs. In this embodiment, the end displacement portion 22b extends in a direction that includes components in the Z-axis direction and the X-axis direction, but it may also extend in a direction that includes only a component in the Z-axis direction.

[0101] The end displacement portion 22b is connected to the end ridge portion 22c at approximately the same height as the top surface 14. The end ridge portion 22c is the portion that extends along the ridge of the side surface 12 and the top surface 14, and is the largest portion of the coil end 22. The end ridge portion 22c is used for welding the coil end 22 to the electrode member 30.

[0102] The buried portion 21 shown in Figures 20 and 21 is the part covered by the magnetic core 10. The buried portion 21 is made by winding a long piece of material and functions as a coil. There are no particular limitations on the number of turns of the buried portion 21; for example, 0.5 turns or 10 turns, etc., can be appropriately selected according to the performance required of the inductor 100A and constraints such as the size of the magnetic core 10. The buried portion 21 is formed, for example, by bending a copper wire covered with an insulating coating. The cross-section of the copper wire constituting the buried portion 21 is, for example, a rectangle with sides in the range of 0.16 to 0.40 mm, and the aspect ratio of the copper wire's cross-section (transverse surface) is 1:1. For example, in the inductor 100A, the cross-section of the copper wire constituting the buried portion 21 is a rectangle with sides of 0.3 mm and an aspect ratio of 1:1. Note that the copper wire constituting the buried portion 21 is not limited to a square wire with such a rectangular cross-section; a round wire with a circular cross-section may also be used.

[0103] The buried portion 21 is positioned such that the wound winding shaft is aligned with the Z-axis direction. The buried portion 21 has a curved portion formed by winding and a straight portion connecting the curved portion and the coil end 22. The straight portion of the buried portion 21 extends in the Y-axis direction toward the side surface 12 of the magnetic core 10 where the coil end 22 is located and is connected to the coil end 22.

[0104] The electrode member 30 shown in Figures 17 and 18 has a side plate 36, a top plate 37, and a bottom plate 34. The side plate 36, top plate 37, and bottom plate 34 are formed by bending metal foil, which is the material of the electrode member 30.

[0105] The electrode member 30 is made of a copper-based metal material, including copper or a copper alloy. For example, in the inductor 100A in this embodiment, a copper electrode member 30 is selected.

[0106] The electrode member 30 is made of a flexible material, for example, a foil material having a thickness of 20 μm or more and less than 100 μm. Specifically, the thickness of the electrode member 30 in this embodiment is 50 μm. The flexibility of the electrode member 30 allows it to be bent to follow the surface of the coil end 22 and the magnetic core 10. The flexibility of the electrode member 30 means that when the electrode member 30 is pressed against the magnetic core 10 and the coil end 22, it has the property of being able to plastically deform in accordance with the surface shape of the magnetic core 10 and the coil end 22. In other words, the electrode member 30 deforms when subjected to an external force and maintains its shape after deformation. The electrode member 30 is not limited to the foil material described above. The thickness of the electrode member 30 is not particularly limited as long as the side plate 36, top plate 37 and bottom plate 34 can be formed by 90° bending in the dimensions of the inductor 100A. However, in cases where the electrode member 30 requires plastic deformation more complex than 90° bending, as in the modified example described later, it is preferable to use the foil material described above.

[0107] The electrode members 30 are provided one on each side of the inductor 100A in the Y-axis direction, i.e., on each side 12, corresponding to each of the two coil ends 22. Here, we will describe one of the two electrode members 30, but the same description applies to the other electrode member 30 as they have the same configuration. The side plate 36, top plate 37, and bottom plate 34 of the electrode member 30 are names given to the respective parts, which are formed by processing a single member made of the same material.

[0108] The side plate 36 shown in Figures 21 and 22 is a part that corresponds to the side surface 12 of the magnetic core 10 and is provided along the side surface 12. The side plate 36 is positioned to overlap the side surface 12 of the magnetic core 10 and the coil end 22.

[0109] The side plate 36 has a width (length in the X-axis direction) greater than the extending length of the magnetic core recess 12b, and completely covers the side surface 12 of the magnetic core recess 12b. The portion of the side plate 36 that overlaps with the coil end 22 (the side plate joint portion 36b described later) is the part that is welded to the coil end 22. The portion of the side plate 36 that covers the magnetic core recess 12b overlaps with the coil end 22 when viewed from a direction perpendicular to the side surface 12.

[0110] The side plate 36 is provided with solder plating. The solder plating is the part that will be soldered when the inductor 100A is mounted on the circuit board (not shown).

[0111] The side plate 36 has a side plate fixing portion 36a and a side plate joining portion 36b.

[0112] The side plate fixing portion 36a is a part that is fixed to the side surface 12 of the magnetic core 10. When viewed from a direction perpendicular to the side surface 12, the side plate fixing portion 36a overlaps the base portion 12a and is fixed to the base portion 12a via an adhesive. The adhesive is a thermosetting adhesive that undergoes a curing reaction with heat, for example, an epoxy resin-based adhesive or a silicone resin-based adhesive. The thermosetting temperature of the adhesive is, for example, 150°C or higher.

[0113] The side plate joint 36b is the part that is welded to the coil end 22. When viewed from a direction perpendicular to the side surface 12, the side plate joint 36b has an overlapping region Ts that overlaps with the coil end 22. The side plate joint 36b is welded to the coil end 22 by laser processing. In other words, a welded portion 40 is formed at the side plate joint 36b and the coil end 22 to connect the side plate 36 and the coil end 22. The welded portion 40 is formed, for example, by irradiating the side plate joint 36b and the coil end 22 with laser light, such as a CW laser. The shape of the welded portion 40 may be strip-shaped or spot-shaped.

[0114] The top plate 37 shown in Figures 21 and 22 is a part that corresponds to the top surface 14 of the magnetic core 10 and is provided along the top surface 14. The top plate 37 is positioned to overlap the top surface 14 of the magnetic core 10 and the coil end 22.

[0115] The top plate 37 has a width (length in the X-axis direction) greater than the extending length of the magnetic core recess 12b, and completely covers the top surface 14 side of the magnetic core recess 12b. The portion of the top plate 37 that overlaps with the coil end 22 (the top plate joint portion 37b described later) is the part that is welded to the coil end 22. The portion of the top plate 37 that covers the magnetic core recess 12b overlaps with the coil end 22 when viewed from a direction perpendicular to the top surface 14. The welded portion 40 is provided on both the top plate 37 and the side plate 36, but it may also be provided on at least one of the top plate 37 and the side plate 36 (for example, only one of the top plate 37 or the side plate 36).

[0116] The top plate 37 is coated with solder plating.

[0117] The top plate 37 has a top plate fixing portion 37a and a top plate joining portion 37b.

[0118] The top plate fixing portion 37a is the part that is fixed to the top surface 14 of the magnetic core 10. When viewed from a direction perpendicular to the top surface 14, the top plate fixing portion 37a overlaps the top surface 14 and is fixed to the top surface 14 via an adhesive. The adhesive is a thermosetting adhesive that undergoes a curing reaction with heat, for example, an epoxy resin-based adhesive or a silicone resin-based adhesive. The thermosetting temperature of the adhesive is, for example, 150°C or higher.

[0119] The top plate joint 37b is the part that is welded to the coil end 22. When viewed from a direction perpendicular to the top surface 14, the top plate joint 37b has an overlapping region Ts that overlaps with the coil end 22. The top plate joint 37b is welded to the coil end 22 by laser processing. In other words, a welded portion 40 for connecting the top plate 37 and the coil end 22 is formed at the top plate joint 37b and the coil end 22. The welded portion 40 is formed, for example, by irradiating the top plate joint 37b and the coil end 22 with laser light such as a CW laser. The shape of the welded portion 40 may be strip-shaped or spot-shaped.

[0120] The bottom plate 34 shown in Figures 18 and 22 is a portion provided to correspond to the bottom surface 13 of the magnetic core 10 and to be positioned along the bottom surface 13. The bottom plate 34 is positioned to overlap the bottom surface 13 of the magnetic core 10.

[0121] The base plate 34 is the part that is fixed to the bottom surface 13 of the magnetic core 10. When viewed from a direction perpendicular to the bottom surface 13, the base plate 34 overlaps the bottom surface 13 and is fixed to the bottom surface 13 via an adhesive. The adhesive is a thermosetting adhesive that undergoes a curing reaction with heat, for example, an epoxy resin-based adhesive or a silicone resin-based adhesive. The thermosetting temperature of the adhesive is, for example, 150°C or higher.

[0122] A solder plating is provided on the surface of the base plate 34 opposite to the magnetic core 10. The solder plating is the part that will be soldered when the inductor 100A is mounted on a circuit board (not shown).

[0123] In this embodiment, a plating layer made of solder plating is formed on each of the side plate 36, bottom plate 34, and top plate 37. Solder plating is tin or a plating mainly composed of tin. The plating region Tp, which is the area where solder plating is provided, is formed on a part of the outer surface 36f of the side plate 36, the entire outer surface 34f of the bottom plate 34, and a part of the outer surface 37f of the top plate 37, as shown in Figures 17 and 18. The outer surface 36f of the side plate 36 is the outer surface located on the opposite side from the magnetic core 10 when viewed from the side plate 36, the outer surface 34f of the bottom plate 34 is the outer surface located on the opposite side from the magnetic core 10 when viewed from the bottom plate 34, and the outer surface 37f of the top plate 37 is the outer surface located on the opposite side from the magnetic core 10 when viewed from the top plate 37.

[0124] The following describes the configuration of the solder plating provided on the outer surface 36f of the side plate 36 and the outer surface 37f of the top plate 37. As shown in Figures 22 and 21, each of the outer surface 36f of the side plate 36 and the outer surface 37f of the top plate 37 is provided with a plated area Tp where solder plating is applied and an unplated area Tn where solder plating is not applied. In Figures 22 and 21, the plated area Tp is shown as an area of ​​hatched dots, and the unplated area Tn is shown as an area without hatching.

[0125] A plated area Tp is provided on at least a portion of the side plate fixing portion 36a and at least a portion of the top plate fixing portion 37a. In this example, more than 80% of the outer surface 36f of the side plate fixing portion 36a and more than 50% of the outer surface 37f of the top plate fixing portion 37a are plated areas Tp, and the portion excluding the plated area Tp is an unplated area Tn.

[0126] The side plate joint 36b and the top plate joint 37b do not have a plated area Tp, but rather a non-plated area Tn. For example, the non-plated area Tn is formed by forming a plating on the entire surface of one main surface of the copper foil that will become the electrode member 30 before bonding the electrode member 30 to the magnetic core 10, and then irradiating this entire plating with a pulsed laser to remove a portion of the plating. The non-plated areas Tn are rectangular in shape when viewed from a direction perpendicular to the side surface 12, and also rectangular when viewed from a direction perpendicular to the top surface 14. The aforementioned welded area 40 is formed in the non-plated area Tn.

[0127] As shown in Figure 22, when comparing the lengths in the direction perpendicular to the bottom surface 13 of the magnetic core 10 (height direction dh), the length Ln of the unplated region Tn is greater than or equal to the length Ls of the overlapping region Ts of the side plate joint 36b (Ln ≥ Ls). For example, the length Ln of the unplated region Tn may be between 1 and 4 times the length Ls of the overlapping region Ts.

[0128] As shown in Figure 21, when comparing the lengths in the direction perpendicular to the side surface 12 of the magnetic core 10 (Y-axis direction), the length Ln of the unplated region Tn is greater than or equal to the length Ls of the overlapping region Ts of the top plate joint 37b (Ln ≥ Ls). For example, the length Ln of the unplated region Tn may be between 1 and 4 times the length Ls of the overlapping region Ts.

[0129] The unplated area Tn is not plated and the copper material is originally exposed, making its surface prone to oxidation. In this example, when the adhesive is cured, heat treatment is performed at a temperature of 150°C or higher in an atmospheric environment, so the unplated area Tn becomes oxidized, i.e., an oxide film is formed. In addition, the surface of the exposed copper material in the unplated area Tn discolors and darkens due to oxidation. When the welded area 40 is formed by laser processing, the copper material melts and solidifies in the area where the welded area 40 is formed, so the oxide film is hardly visible. However, in the unplated area Tn excluding the welded area 40, the metal material (copper material) of the electrode member 30 is oxidized and darkened. For example, the surface brightness of the area of ​​the unplated area Tn excluding the welded area 40 is lower than that of the welded area 40 and the plated area Tp.

[0130] For example, when a coil end 22 and an electrode member 30 are overlapped and welded by laser processing, and the welded part 40 is visually inspected using a camera, it is difficult to determine the quality of the welded part 40 if the difference in brightness between the welded part 40 and the surrounding material is small. Also, if the area around the welded part 40 is made of a material that reflects light, such as plating, it is difficult to determine the quality of the welded part 40.

[0131] In contrast, in this embodiment, the surface of the copper material is oxidized by heat treatment without plating, thereby making the brightness of the area excluding the welded portion 40 lower than the brightness of the welded portion 40 and the plated area Tp, respectively. As a result, the difference in brightness between the welded portion 40 and the area surrounding the welded portion 40 can be made larger. This allows for accurate quality judgment by visual inspection and improves inspection quality.

[0132] The inductor 100A of this embodiment comprises a magnetic core 10, a coil element 20, and an electrode member 30. The magnetic core 10 contains a magnetic material and has a three-dimensional shape with side surfaces 11 and 12, a bottom surface 13, and a top surface 14. The coil element 20 contains a metal material and has an embedded portion 21 and a coil end 22. The embedded portion 21 is embedded in the magnetic core 10. The coil end 22 is exposed from the magnetic core 10 and extends along the side surface 12 of the magnetic core 10. The electrode member 30 contains a metal material and is welded to the coil end 22. A magnetic core recess 12b is provided on the ridge line connecting the side surface 12 and the top surface 14 of the magnetic core 10, extending along the ridge line and recessed toward the interior of the magnetic core 10. The coil end 22 is housed in the magnetic core recess 12b and extends in the direction in which the magnetic core recess 12b extends. The electrode member 30 has a side plate 36 and a top plate 37. The side plate 36 is arranged along the side surface 12 of the magnetic core 10 and completely covers the side surface 12 of the magnetic core recess 12b. The top plate 37 is arranged along the top surface 14 of the magnetic core 10 and completely covers the top surface 14 of the magnetic core recess 12b. The electrode member 30 is welded to the coil end 22 at a point where it directly faces and overlaps with the coil end 22. The side plate 36 includes a side plate fixing portion 36a and a side plate joining portion 36b. The side plate fixing portion 36a is fixed to the side surface 12 of the magnetic core 10. The side plate joining portion 36b is welded to the coil end 22. The outer surface 36f of the side plate 36 is provided with a plated area Tp and an unplated area Tn. The plated area Tp is plated with tin or a solder plating mainly composed of tin. The unplated area Tn is not solder-plated. A plated area Tp is provided in at least a portion of the side plate fixing portion 36a. The side plate joining portion 36b does not have a plated area Tp, but it does have an unplated area Tn.

[0133] In this way, by providing an unplated area Tn in the side plate joint 36b, the unplated area Tn can be oxidized when, for example, the adhesive used to bond the electrode member 30 and the magnetic core 10 is heat-treated and heat-cured. As a result, the difference in brightness between the welded area and the unplated area Tn surrounding the welded area can be increased. This allows for accurate quality control through visual inspection, thereby improving the inspection quality of the inductor 100A.

[0134] Furthermore, in the inductor 100A according to this embodiment, a magnetic core recess 12b is provided on the ridges of the side surface 12 and top surface 14 of the magnetic core 10, allowing the coil end 22 for connecting the electrode member 30 and the coil element 20 to be housed within the magnetic core recess 12b. The magnetic core recess 12b is provided at a relatively high position in contact with the top surface 14, and extends in a direction that intersects with the direction perpendicular to the top surface 14 and bottom surface 13, that is, in a direction that does not significantly affect the height, thus making it easy to reduce the height of the inductor 100A. On the other hand, the magnetic core recess 12b is completely covered by the side plate 36 and top plate 37 of the electrode member 30. The electrode member 30 is made of copper-based metal foil, which is thinner than metal fittings such as copper plates. Therefore, a flat surface can be maintained on the top surface 14 of the inductor 100A, making it easy to attach using a mounting suction nozzle. Thus, the inductor 100A can be easily reduced in height while maintaining ease of mounting.

[0135] [Manufacturing Method] Next, the manufacturing method of the inductor 100A described above will be explained with reference to Figures 23 and 24.

[0136] Figure 23 is a flowchart showing the manufacturing method of the inductor 100A according to Embodiment 2. Figure 24 is a diagram showing the configuration during the manufacturing process of the inductor 100A according to Embodiment 2.

[0137] In the manufacturing method of the inductor 100A, first, as shown in Figure 24(a), the coil element 20 is formed by winding a wire (step S101). This forms a coil element 20 having a winding portion and an end.

[0138] Next, as shown in Figure 24(b), the magnetic core 10 is molded by pressure molding (step S102). This molding of the magnetic core 10 is carried out by pressure molding the compacted magnetic core so as to enclose the winding portion of the coil element 20. Magnetic core recesses 12b are formed on the two sides 12 of the magnetic core 10. After step S102, the insulating coating on the ends of the coil element 20 protruding from the magnetic core recesses 12b is removed.

[0139] Next, as shown in Figure 24(c), a step (step S103) is performed in which the end of the coil element 20 is bent along the side surface 12 and top surface 14 of the magnetic core 10 so that it is housed in the magnetic core recess 12b.

[0140] Next, as shown in Figure 24(d), adhesive is applied to the two sides 12 of the magnetic core 10 (step S104). Furthermore, although not shown, adhesive is also applied to a portion of the top surface 14 and a portion of the bottom surface 13. The adhesive is applied to each surface of the magnetic core 10, for example, by printing.

[0141] Next, as shown in Figure 24(e), electrode members 30 are attached to each of the two sides 12 of the magnetic core 10 (step S105). In step S105, electrode members 30, which have been pre-bent and formed to have a top plate 37, side plates 36 and a bottom plate 34, are attached to the top surface 14, side surfaces 12 and bottom surface 13 of the magnetic core 10. This fixes the side plates 36 of the electrode members 30 to each surface of the magnetic core 10.

[0142] Next, as shown in Figure 24(f), a step (step S106) is performed in which the electrode member 30 and the coil end 22 are welded together by overlapping laser welding. This welds the electrode member 30 to the coil end 22, forming a welded portion 40. Although not shown, when forming a welded portion 40 on the top plate 37, it is preferable to perform laser welding from a direction intersecting the top surface 14.

[0143] Next, the inductor 100A manufactured in steps S101 to S106 is visually inspected. As described above, by not plating the side plate joint 36b and the top plate joint 37b and by heat treatment to oxidize the surface of the copper material, the brightness around the welded part 40 can be made lower than the brightness of the welded part 40 and the brightness of the plated area Tp. This makes it possible to accurately determine whether the welded part 40 is good or bad by visual inspection and improves inspection quality.

[0144] The method for manufacturing the inductor 100A according to this embodiment includes an element formation step, a magnetic core formation step, a bending step, a fixing step, and a welding step. In the element formation step, a coil element 20 having a winding portion and a coil end 22 is formed. In the magnetic core formation step, when forming a rectangular parallelepiped-shaped magnetic core 10 having a magnetic core recess 12b extending along the ridge line of the side surface 12 and top surface 14, the winding portion is embedded so that the coil end 22 protrudes from the magnetic core recess 12b to form the magnetic core 10. In the bending step, the coil end 22 protruding from the magnetic core recess 12b is housed within the magnetic core recess 12b and the coil end 22 is bent so that it extends in the direction in which the magnetic core recess 12b extends. In the fixing step, the side plate 36 and top plate 37 of the electrode member 30 are fixed to the side surface 12 and top surface 14 of the magnetic core 10 so as to completely cover the magnetic core recess 12b together with the coil end 22 placed within the magnetic core recess 12b. In the welding process, the electrode member 30 is welded to the coil end 22.

[0145] In this embodiment as well, before the fixing process, the electrode member 30 is provided with a plated area Tp and an unplated area Tn. In the fixing process, heat treatment is performed in an atmospheric environment to cure the adhesive, and this heat treatment causes the unplated area Tn to oxidize, resulting in a darkened surface. In the welding process, a welded area 40 is formed in the unplated area Tn by laser processing.

[0146] In this way, by not plating the side plate joint 36b and instead performing heat treatment to oxidize the surface of the copper material, the brightness around the welded area can be made lower than the brightness of the welded area and the brightness of the plated area Tp. This allows for accurate quality judgment of the welded area by visual inspection, thereby improving the inspection quality of the inductor 100A.

[0147] Furthermore, by forming the magnetic core recess 12b on the ridges of the side surface 12 and the top surface 14, and housing the coil end 22 in the magnetic core recess 12b, a low-profile inductor 100A can be manufactured. Then, by covering the magnetic core recess 12b with the side plate 36 and the top plate 37, which are part of the electrode member 30, an inductor 100A can be manufactured that maintains ease of mounting, allowing it to be attached using a mounting suction nozzle.

[0148] (Summary) An example of an inductor (100, 100A) according to one embodiment of the present disclosure is given below.

[0149] The inductor (100, 100A) of Example 1 comprises a magnetic core 10, a coil element 20, and an electrode member 30. The magnetic core 10 contains a magnetic material and has a three-dimensional shape with a side surface 12, a bottom surface 13, and a top surface 14. The coil element 20 contains a metal material and has an embedded portion 21 and a coil end 22. The embedded portion 21 is embedded in the magnetic core 10, and the coil end 22 is exposed from the magnetic core 10 and extends along the side surface 12. The electrode member 30 contains a metal material and is welded to the coil end 22. The electrode member 30 has a side plate 36, which is arranged along the side surface 12 of the magnetic core 10. The side plate 36 includes a side plate fixing portion 36a and a side plate joining portion 36b. The side plate fixing portion 36a is fixed to the side surface 12 of the magnetic core 10. The side plate joining portion 36b is welded to the coil end 22. The outer surface 36f of the side plate 36 is provided with a plated area Tp and an unplated area Tn. The plated area Tp is plated with tin or solder plating mainly composed of tin. The unplated area Tn is not plated with solder plating. At least a part of the side plate fixing portion 36a is provided with a plated area Tp. The side plate joining portion 36b is not provided with a plated area Tp but is provided with an unplated area Tn.

[0150] In this way, by providing an unplated area Tn in the side plate joint 36b, the unplated area Tn can be oxidized when, for example, the adhesive used to bond the electrode member 30 and the magnetic core 10 is heat-treated and heat-cured. As a result, the difference in brightness between the welded portion of the side plate joint 36b and the unplated area Tn surrounding the welded portion can be increased. This allows for accurate quality judgment through visual inspection, thereby improving the inspection quality of the inductor.

[0151] The inductor (100, 100A) in Example 2 is the inductor described in Example 1, and the side plate joint 36b has an overlapping region Ts that overlaps the coil end 22 when viewed from a direction perpendicular to the side surface 12. The width direction dw is defined as the direction along the side surface 12 of the magnetic core 10 and parallel to the bottom surface 13, and when comparing the dimensions in the width direction dw, the width wn of the unplated region Tn may be 1 or more and 4 or less than the width ws of the overlapping region Ts.

[0152] This allows for the specification of dimensions necessary for properly determining the quality of welded parts. This enables accurate quality determination through visual inspection, thereby improving the inspection quality of inductors.

[0153] The inductor (100, 100A) in Example 3 is the inductor described in Example 1, and the side plate joint 36b has an overlapping region Ts that overlaps the coil end 22 when viewed from a direction perpendicular to the side surface 12. When comparing the lengths in the direction perpendicular to the bottom surface 13 of the magnetic core 10, the length Ln of the unplated region Tn may be 1 or more and 4 or less than the length Ls of the overlapping region Ts.

[0154] This allows for the specification of dimensions necessary for properly determining the quality of welded parts. This enables accurate quality determination through visual inspection, thereby improving the inspection quality of inductors.

[0155] The inductor (100, 100A) in Example 4 is the inductor described in any of Examples 1 to 3, wherein a welded portion 40 is formed in the unplated region Tn where the coil end 22 and the side plate joint portion 36b are welded, and the surface of the metal material of the electrode member 30 in the region of the unplated region Tn excluding the welded portion 40 may be more oxidized than the welded portion 40.

[0156] According to this, the physical conditions necessary for properly determining the quality of the welded joint 40 can be defined. This allows for accurate quality determination by visual inspection, thereby improving the inspection quality of the inductor.

[0157] The inductor (100, 100A) in Example 5 is the inductor described in any of Examples 1 to 3, wherein a welded portion 40 is formed in the unplated region Tn where the coil end 22 and the side plate joint 36b are welded, and the area of ​​the unplated region Tn excluding the welded portion 40 may have a lower surface brightness than the welded portion 40.

[0158] This allows for the identification of surface condition indicators necessary for appropriately determining the quality of the welded joint 40. This enables accurate quality determination through visual inspection and improves the inspection quality of the inductor.

[0159] The inductor (100, 100A) in Example 6 is the inductor described in any of Examples 1 to 3, wherein a welded portion 40 is formed in the unplated region Tn where the coil end 22 and the side plate joint 36b are welded, and the surface brightness of the region of the unplated region Tn excluding the welded portion 40 may be lower than that of the welded portion 40 and the plated region Tp.

[0160] This allows for the identification of surface condition indicators necessary for appropriately determining the quality of the welded joint 40. This enables accurate quality determination through visual inspection and improves the inspection quality of the inductor.

[0161] The inductor (100) of Example 7 comprises a magnetic core 10, a coil element 20, and an electrode member 30. The magnetic core 10 contains a magnetic material and has a three-dimensional shape with a side surface 12, a bottom surface 13, and a top surface 14. The coil element 20 contains a metal material and has an embedded portion 21 and a coil end 22. The embedded portion 21 is embedded in the magnetic core 10. The coil end 22 is exposed from the magnetic core 10 and extends along the side surface 12 of the magnetic core 10. The electrode member 30 contains a metal material and is welded to the coil end 22. The side surface 12 of the magnetic core 10 is provided with a magnetic core recess 12b that is recessed toward the inside of the magnetic core 10. The coil end 22 protrudes from the magnetic core recess 12b and extends along the inner bottom surface 12b1 of the magnetic core recess 12b. The electrode member 30 is a copper-based metal foil with a thickness of less than 100 μm and has a side plate 36 and a bottom plate 34. The side plate 36 is positioned along the side surface 12 of the magnetic core 10. The bottom plate 34 is positioned along the bottom surface 13 of the magnetic core 10. The side plate 36 has a side plate fixing portion 36a, a side plate joining portion 36b, and a side plate recess 36c. The side plate fixing portion 36a is fixed to the side surface 12 of the magnetic core 10. The side plate joining portion 36b is welded to the coil end 22. The side plate recess 36c is connected to the side plate fixing portion 36a and the side plate joining portion 36b and is recessed in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b. The outer surface 36f of the side plate 36 is provided with a plated area Tp and an unplated area Tn. The plated area Tp is plated with tin or solder plating mainly composed of tin. The unplated area Tn is not plated with solder plating. A plated area Tp is provided in at least a portion of the side plate fixing portion 36a and the side plate recess 36c. The side plate joining portion 36b does not have a plated area Tp, but a non-plated area Tn is provided.

[0162] In this way, by providing an unplated area Tn in the side plate joint 36b, the unplated area Tn can be oxidized when, for example, the adhesive used to bond the electrode member 30 and the magnetic core 10 is heat-treated and heat-cured. As a result, the difference in brightness between the welded portion of the side plate joint 36b and the unplated area Tn surrounding the welded portion can be increased. This allows for accurate quality judgment through visual inspection, thereby improving the inspection quality of the inductor.

[0163] The inductor (100A) of Example 8 comprises a magnetic core 10, a coil element 20, and an electrode member 30. The magnetic core 10 contains a magnetic material and has a three-dimensional shape with side surfaces 11 and 12, a bottom surface 13, and a top surface 14. The coil element 20 contains a metallic material and has an embedded portion 21 and a coil end 22. The embedded portion 21 is embedded in the magnetic core 10. The coil end 22 is exposed from the magnetic core 10 and extends along the side surface 12 of the magnetic core 10. The electrode member 30 contains a metallic material and is welded to the coil end 22. A magnetic core recess 12b is provided on the ridge line connecting the side surface 12 and the top surface 14 of the magnetic core 10, extending along the ridge line and recessed toward the interior of the magnetic core 10. The coil end 22 is housed in the magnetic core recess 12b and extends in the direction in which the magnetic core recess 12b extends. The electrode member 30 has a side plate 36 and a top plate 37. The side plate 36 is arranged along the side surface 12 of the magnetic core 10 and completely covers the side surface 12 of the magnetic core recess 12b. The top plate 37 is arranged along the top surface 14 of the magnetic core 10 and completely covers the top surface 14 of the magnetic core recess 12b. The electrode member 30 is welded to the coil end 22 at a location where it directly faces and overlaps with the coil end 22. The side plate 36 includes a side plate fixing portion 36a and a side plate joining portion 36b. The side plate fixing portion 36a is fixed to the side surface 12 of the magnetic core 10. The side plate joining portion 36b is welded to the coil end 22. The outer surface 36f of the side plate 36 is provided with a plated area Tp and an unplated area Tn. The plated area Tp is plated with tin or solder plating mainly composed of tin. The unplated area Tn is not solder-plated. A plated area Tp is provided in at least a portion of the side plate fixing portion 36a. The side plate joining portion 36b does not have a plated area Tp, but it does have an unplated area Tn.

[0164] In this way, by providing an unplated area Tn in the side plate joint 36b, the unplated area Tn can be oxidized when, for example, the adhesive used to bond the electrode member 30 and the magnetic core 10 is heat-treated and heat-cured. As a result, the difference in brightness between the welded area and the unplated area Tn surrounding the welded area can be increased. This allows for accurate quality control through visual inspection, thereby improving the inspection quality of the inductor 100A.

[0165] (Other Embodiments, etc.) Although the inductors according to Embodiments 1 and 2 of this disclosure have been described above, this disclosure is not limited to Embodiments 1 and 2.

[0166] For example, electrical products or circuits using the above-described inductor are also included in this disclosure. Examples of electrical products include power supply devices equipped with the above-described inductor, and various devices equipped with said power supply devices.

[0167] Furthermore, this disclosure is not limited to these two embodiments. Without departing from the spirit of this disclosure, various modifications to these embodiments that a person skilled in the art could conceive of, or forms constructed by combining components from different embodiments, may also be included within the scope of one or more embodiments.

[0168] The inductor relating to this disclosure is useful as an inductor for use in various devices and equipment.

[0169] 10 Magnetic core 11, 12 Side surface 12a Base 12b Magnetic core recess 12b1 Inner bottom surface 12b2 Inner wall surface 13 Bottom surface 14 Top surface 20 Coil element 21 Embedded part 22 Coil end 22a Exposed end part 22b Displaced end part 22c End ridge part 22f1 End outer surface 22f2 End inner surface 22s End side surface 30 Electrode member 34 Bottom plate 34f Outer surface 36 Side plate 36a Side plate fixing part 36b Side plate joint part 36c Side plate recess 36c1 Inner bottom part 36c2 Inner wall part 36f Outer surface 37 Top plate 37a Top plate fixing part 37b Top plate joint part 37f Outer surface 40 Welded part 80 Pressing jig 100, 100A Inductor dh Height direction dp1, dp2 Depth dw Width direction H1, Hs Height Ln Length of unplated area Tn Ls Length of overlapping area Ts m1 First corner m2 Second corner n1 First bend n2 Second bend Tp Plated area Tn Unplated area Ts Overlapping area wn Width of unplated area Tn ws Width of overlapping area Ts

Claims

1. An inductor comprising: a magnetic core having a three-dimensional shape including a magnetic material and having sides, a bottom surface and a top surface; a coil element including a metal material and having an embedded portion embedded in the magnetic core and a coil end exposed from the magnetic core and extending along the sides; and an electrode member including a metal material and welded to the coil end, wherein the electrode member has a side plate arranged along the sides of the magnetic core, the side plate includes a side plate fixing portion fixed to the sides of the magnetic core and a side plate joining portion welded to the coil end, the outer surface of the side plate is provided with a plated area where tin or a solder mainly composed of tin is applied and an unplated area where the solder plating is not applied, at least a part of the side plate fixing portion is provided with the plated area, and the side plate joining portion is not provided with the plated area but is provided with the unplated area.

2. The inductor according to claim 1, wherein the side plate joint has an overlapping region that overlaps the coil end when viewed from a direction perpendicular to the side surface, and the width direction is defined as the direction along the side surface of the magnetic core and parallel to the bottom surface, and when comparing the dimensions in the width direction, the width of the unplated region is at least 1 and at least 4 times the width of the overlapping region.

3. The inductor according to claim 1, wherein the side plate joint has an overlapping region that overlaps with the coil end when viewed from a direction perpendicular to the side surface, and when compared in length perpendicular to the bottom surface of the magnetic core, the length of the unplated region is at least 1 and at least 4 times the length of the overlapping region.

4. The inductor according to any one of claims 1 to 3, wherein a welded portion is formed in the unplated region where the coil end and the side plate joint are welded, and the surface of the metal material of the electrode member in the region of the unplated region excluding the welded portion is more oxidized than that of the welded portion.

5. The inductor according to any one of claims 1 to 3, wherein a welded portion is formed in the unplated region where the coil end and the side plate joint are welded, and the region of the unplated region excluding the welded portion has a lower surface brightness than the welded portion.

6. The inductor according to any one of claims 1 to 3, wherein a welded portion is formed in the unplated region where the coil end and the side plate joint are welded, and the region of the unplated region excluding the welded portion has a lower surface brightness than the welded portion and the plated region.

7. A magnetic core comprising a magnetic material and having a three-dimensional shape with sides, bottom and top surfaces; a coil element comprising a metal material and having an embedded portion embedded in the magnetic core and a coil end exposed from the magnetic core and extending along the sides of the magnetic core; an electrode member comprising a metal material and welded to the coil end, wherein the sides of the magnetic core are provided with magnetic core recesses that are recessed toward the interior of the magnetic core; the coil end protrudes from the magnetic core recess and extends along the inner bottom surface of the magnetic core recess; the electrode member is a copper-based metal foil with a thickness of less than 100 μm and has a side plate arranged along the side surface of the magnetic core and a bottom plate arranged along the bottom surface of the magnetic core; the side plate has a side plate fixing portion fixed to the side surface of the magnetic core, a side plate joint portion welded to the coil end, and a side plate recess connected to the side plate fixing portion and the side plate joint portion and recessed toward the inner bottom surface of the magnetic core recess. An inductor wherein the outer surface of the side plate is provided with a plated area where tin or a solder plate mainly composed of tin is applied, and an unplated area where the solder plate is not applied, and the plated area is provided in at least a part of the side plate fixing portion and the side plate recess, and the unplated area is provided in the side plate joining portion but the plated area is not provided.

8. A magnetic core having a three-dimensional shape including a magnetic material and having sides, a bottom, and a top surface; a coil element including a metal material and having an embedded portion embedded in the magnetic core and a coil end exposed from the magnetic core and extending along the sides of the magnetic core; an electrode member including a metal material and welded to the coil end, wherein a magnetic core recess is provided in the ridge portion connecting the sides and top surface of the magnetic core, extending along the ridge and recessing toward the interior of the magnetic core; the coil end is housed in the magnetic core recess and extends in the direction in which the magnetic core recess extends; the electrode member has a side plate arranged along the sides of the magnetic core and completely covering the side side of the magnetic core recess, and a top plate arranged along the top surface of the magnetic core and completely covering the top side of the magnetic core recess, and is welded to the coil end at a location where it directly faces and overlaps with the coil end; the side plate includes a side plate fixing portion fixed to the side surface of the magnetic core and a side plate joining portion welded to the coil end. An inductor wherein the outer surface of the side plate is provided with a plated area where tin or a solder plate mainly composed of tin is applied, and an unplated area where the solder plate is not applied, and at least a part of the side plate fixing portion is provided with the plated area, and the side plate joint portion is not provided with the plated area but is provided with the unplated area.

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