Inductor

Abstract

This inductor comprises: a magnetic core having a bottom surface that faces a circuit board when mounted on the circuit board; a coil element having an embedded portion and a coil end portion; an electrode member that has a thickness of less than 100 μm, and includes a side plate which has a side plate joining portion joined to the coil end portion and a side plate fixing portion fixed to a side surface of the magnetic core, and which is disposed along the side surface of the magnetic core; and an adhesive for bonding and fixing the side plate fixing portion to the side surface of the magnetic core. The adhesive has a region where a present portion in which the adhesive is present between the side surface of the magnetic core and the side plate and a void portion in which the adhesive is not present between the side surface of the magnetic core and the side plate are alternately repeated in a prescribed direction parallel to the side surface.

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 purposes 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. The inductor includes 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 Patent Application Laid-Open No. 2011-249770 International Publication No. WO 2022 / 091761

[0004] Conventional inductors sometimes fail to operate properly.

[0005] An inductor according to an aspect of the present disclosure includes: a three-dimensional magnetic core containing a magnetic material, the magnetic core having a side surface, a top surface, and a bottom surface facing a circuit board when mounted on the circuit board; a coil element containing a metal material, the 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 of the magnetic core; and an electrode member having a thickness of less than 100 µm, the electrode member containing a metal material, having a side plate joint portion joined to the coil end and a side plate fixing portion fixed to the side surface of the magnetic core, and including a side plate disposed along the side surface of the magnetic core; and an adhesive that adhesively fixes the side plate fixing portion to the side surface of the magnetic core. The adhesive has a region arranged such that a plurality of existing portions where the adhesive is present between the side surface of the magnetic core and the side plate, and a plurality of void portions where the adhesive is not present between the side surface of the magnetic core and the side plate are alternately repeated in a predetermined direction parallel to the side surface.

[0006] According to the inductor of the present disclosure, it can operate more properly.

[0007] Figure 1 is a perspective view of an inductor according to an embodiment. 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 the line IV-IV shown in Figure 3. Figure 5 is a view of the inductor according to an embodiment from the top side. Figure 6 is a view of the inductor according to an embodiment from the side side. Figure 7 is a cross-sectional view of the inductor taken along the line VII-VII shown in Figure 1. Figure 8 is a cross-sectional view of the inductor taken along the 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 bent portion and the second bent portion provided on the side plate of the electrode member of the inductor. Figure 11 is a diagram illustrating the configuration of the adhesive for fixing the electrode member of the inductor according to an embodiment. Figure 12 is a diagram illustrating the configuration of the adhesive for fixing the electrode member of the inductor according to an embodiment. Figure 13 is a cross-sectional view of an inductor mounting example from the same viewpoint as Figure 4. Figure 14 is a diagram illustrating the void ratio of the inductor according to the embodiment. Figure 15 is a flowchart of the manufacturing method of the inductor according to the embodiment. Figure 16 is a diagram showing the form of the inductor during the manufacturing process according to the embodiment. Figure 17 is a schematic diagram showing various processes applied to the side plate of the electrode member of the inductor according to the embodiment. Figure 18 is a schematic diagram showing the magnetic core, coil end and electrode member of the inductor of Comparative Example 1. Figure 19 is a schematic diagram showing the magnetic core, coil end and electrode member of the inductor of Comparative Example 2. Figure 20 is a schematic diagram showing the magnetic core, coil end and electrode member of the inductor of Comparative Example 3. Figure 21 is a perspective view of an inductor according to a modified example of the embodiment.

[0008] (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.

[0009] Conventional inductors are known, such as those described in Patent Document 1, which include 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, wherein 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, and the inductor is positioned between the flat terminal and the magnetic core.

[0010] Furthermore, as shown in Patent Document 2, an inductor is also known which comprises a magnetic core having a three-dimensional shape with a bottom surface, side surfaces and a top surface and containing a magnetic material; 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 disposed on the opposite side from the magnetic core with the coil end in between and having a plating layer on its surface, wherein the electrode member has a side portion that partially overlaps the coil end, the electrode member and the magnetic core are bonded via an adhesive layer, and the electrode member and the coil end are welded in at least a portion of the region where the side portion and the coil end overlap.

[0011] However, when an inductor is mounted on a circuit board, the mounting reliability of the inductor may be compromised, and the electrical product consisting of the inductor and the circuit board on which the inductor is mounted may not function properly. Therefore, in view of the above, this disclosure provides an inductor that functions more properly by improving the mounting reliability of the inductor. The embodiments will be described in more detail below with reference to the drawings.

[0012] 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 the order of steps 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.

[0013] 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.

[0014] (Embodiment) [Configuration] The inductor according to the embodiment will be described with reference to Figures 1 to 14.

[0015] Figure 1 is a perspective view of an inductor according to an embodiment. 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 elements of the inductor shown in Figure 1. Figure 4 is a cross-sectional view of the magnetic core and coil elements of the inductor taken along the line IV-IV shown in Figure 3. Figure 5 is a view of the inductor according to an embodiment from the top side. Figure 6 is a view of the inductor according to an embodiment from the side side.

[0016] Figure 3 shows the inductor 100 with the electrode member 30 removed. In Figure 4, the hatching of the magnetic core 10 is omitted.

[0017] As shown in Figures 1 and 2, the inductor 100 according to the embodiment comprises a magnetic core 10, a coil element 20, and an electrode member 30.

[0018] The inductor 100, for example, has a rectangular prism-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, 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 composed of a magnetic core 10 with dimensions of 4 mm to 12 mm in the X-axis direction, 4 mm to 12 mm in the Y-axis direction, and 2 mm to 8 mm in the Z-axis direction. For example, the inductor 100 may have dimensions of 6 mm in the X-axis direction, 6 mm in the Y-axis direction, and 3 mm in the Z-axis direction.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] Figure 7 is a cross-sectional view of the inductor along the line VII-VII shown in Figure 1.

[0023] 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.

[0024] As shown in Figures 3 and 4, the magnetic core recess 12b extends toward the top surface 14 and reaches the top surface 14, with the top surface 14 side of the magnetic core recess 12b being open. 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.

[0025] 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.

[0026] 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 extends along the side surface 12 toward 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 in the extension direction E22, 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 from the magnetic core recess 12b toward the positive Z-axis direction.

[0027] As shown in Figure 7, the coil end 22 has an outer end surface 22f1 that contacts the side plate joint 36b, an inner end surface 22f2 that faces away from the outer end surface 22f1 and towards 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. Note that the magnetic core recess 12b is not an essential component. For example, even if the inductor is made of a magnetic core with flat sides without a magnetic core recess 12b, if the stress on the solder 155 (described later) can be reduced by the configuration of the adhesive 154, the inductor 100 can be used more effectively.

[0028] 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 circular with a diameter of 0.16 to 1.40 mm, and the aspect ratio of the copper wire's cross-section (transverse surface) is 1:1. For example, in the inductor 100, the cross-section of the copper wire constituting the buried portion 21 is circular with a diameter of 0.4 mm and an aspect ratio of 1:1.

[0029] 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.

[0030] 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.

[0031] The electrode member 30 is made of a material selected from metallic materials such as aluminum, copper, silver, and gold, as well as alloys consisting of metals and other substances. For example, in the inductor 100 in this embodiment, a copper-based electrode member 30 including copper or a copper alloy is selected.

[0032] 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 T1 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.

[0033] The electrode members 30 are provided one on each side in the Y-axis direction of the inductor 100, 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 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.

[0034] The side plate 36 shown in Figures 5 and 6 is a portion provided along the side surface 12 of the magnetic core 10, corresponding to the side surface 12 of the magnetic core 10. The side plate 36 is positioned to overlap the base 12a and the coil end 22 of the side surface 12 of the magnetic core 10.

[0035] The side plate 36 has a side plate fixing portion 36a, a side plate joining portion 36b, and a side plate recess 36c.

[0036] The side plate fixing portion 36a is the part that is fixed to the side surface 12 of the magnetic core 10 by adhesive 154 (see Figure 11, etc., described later). 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 adhesive 154 (see Figures 16 and 17). In this way, the side plate 36 is fixed to the magnetic core 10 by adhesive fixing between the side plate fixing portion 36a and the base portion 12a. As the adhesive 154, for example, a resin adhesive such as a thermosetting epoxy resin or a silicone resin is used.

[0037] The side plate joint 36b is the portion that is joined to the coil end 22. Figures 1 and 6 show multiple spot-shaped joining regions 40. When viewed from a direction perpendicular to the side surface 12, the side plate joint 36b overlaps the coil end 22 and is joined to the coil end 22 by, for example, laser welding.

[0038] 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 17(d)) ​​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.

[0039] As shown in Figure 7, the side plate recess 36c formed by the pressing jig 80 has an inner bottom portion 36c1 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 on the inner bottom surface 12b1 side of the magnetic core recess 12b rather than the side surface 12 and the outer end surface 22f1 of the coil end 22. The inner wall portion 36c2 has an inclined surface that is inclined with respect to the inner bottom portion 36c1 and the side plate fixing portion 36a. The side plate recess 36c is tapered in the direction from the side plate fixing portion 36a toward the inner bottom portion 36c1. The inclination angle of the inner wall portion 36c2 with respect to the inner bottom portion 36c1 is smaller than the inclination angle of the inner wall surface 12b2 with respect to the inner bottom surface 12b1.

[0040] For example, the depth dp2 of the side plate recess 36c is 0.3 times or more and 0.9 times or less of the depth dp1 of the magnetic core recess 12b. The side plate recess 36c does not contact the inner bottom surface 12b1 of the magnetic core recess 12b, and there is a predetermined gap 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 with the pressing jig 80, but in order to maintain the shape after deformation, it is desirable that the depth dp2 of the side plate recess 36c be 1 / 2 or more of the thickness T1 of the electrode member 30.

[0041] Figure 8 is a cross-sectional view of the inductor taken along the 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 bent portions provided on the side plate of the electrode member of the inductor.

[0042] 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 that serves 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. The plurality of first corner portions m1 are formed along the inner wall surface 12b2 of the magnetic core recess 12b when viewed from a direction perpendicular to the side surface 12 of the magnetic core 10 (see FIG. 9). Among the plurality of first corner portions m1, two first corner portions m1 are each 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.

[0043] As shown in FIGS. 7 and 9, the coil end portion 22 has two second corner portions m2 located at the boundary between the end outer surface 22f1 and the end side surface 22s. The second corner portion m2 is a corner portion formed by the end outer surface 22f1 and the end side 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 E22 of the coil end portion 22.

[0044] 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 a pressing jig 80 is pressed into a part of the side plate 36 to form the side plate recess 36c.

[0045] 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 (not shown). 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.

[0046] 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 direction of the inner bottom surface 12b1 of the magnetic core recess 12b.

[0047] The two first corner portions m1 shown in Fig. 7 are arranged side by side 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 direction. Each of the two first bent portions n1 is located diagonally inward of the two first corner portions m1, and abuts against the two first corner portions m1 located diagonally outward of the two first bent portions n1. With the arrangement configuration of these two first corner portions m1 and two first bent portions n1, the position of the magnetic core 10 with the electrode member 30 as a reference is restricted in the X-axis direction. Thereby, the vibration resistance of the inductor 100 is improved.

[0048] Furthermore, the two second corner portions m2 shown in Fig. 7 are arranged side by side in a direction along the end outer surface 22f1 and perpendicular to the extending direction E22 of the coil end portion 22, that is, in a direction along the X-axis direction. Each of the two second bent portions n2 is located diagonally outward of the two second corner portions m2, and abuts against the two second corner portions m2 located diagonally inward of the two second bent portions n2. With the arrangement configuration of these two second corner portions m2 and two second bent portions n2, the position of the coil end portion 22 with the electrode member 30 as a reference is restricted in the X-axis direction. Thereby, the vibration resistance of the inductor 100 is improved.

[0049] The first corner portion m1 shown in Figure 8 is provided on the bottom surface 13 side 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 opposite the bottom surface 13 of the magnetic core 10. The bottom plate 34 is bonded to the bottom surface 13, for example, with an adhesive 154 similar to that used for the side plate 36, and is fixed to the bottom surface 13 of the magnetic core 10 through the adhesive 154. 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. The 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 with respect to the electrode member 30 in the Z-axis direction. This improves the vibration resistance of the inductor 100.

[0050] 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.

[0051] Furthermore, the configuration of the adhesive used to bond and fix the side plate 36 to the side surface 12 of the magnetic core 10 of the inductor 100 will be described below. Figures 11 and 12 are diagrams illustrating the configuration of the adhesive used to fix the electrode member of the inductor according to the embodiment.

[0052] As described above, the inductor 100 has its side plate 36 (particularly the side plate fixing portion 36a) fixed to the side surface 12 (particularly the base portion 12a) of the magnetic core 10 by adhesive 154. At this time, the adhesive 154 is arranged such that in a certain area (lower region 162) involved in bonding, there are multiple existing portions 154b where the adhesive 154 is present and multiple void portions 154s that are voids. For example, as shown in Figures 11 and 12, the adhesive 154 includes the main portion 154a of the adhesive 154 provided in the upper region 161 that sandwiches the magnetic core recess 12b of the base portion 12a in the horizontal direction (X-axis direction), and the existing portion 154b of the adhesive 154 provided in the lower region 162 that is below (towards the bottom surface 13) in the vertical direction (Z-axis direction) from the magnetic core recess 12b of the base portion 12a.

[0053] The upper region 161 (main portion 154a) is provided with adhesive 154 as widely as possible where the base portion 12a and the side plate fixing portion 36a overlap, and functions as the main part for ensuring the fixing strength of the side plate 36. That is, in this embodiment shown in Figures 11 and 12, the upper region 161 (existing portion 154a) does not have a gap where the base portion 12a and the side plate fixing portion 36a overlap. On the other hand, the lower region 162 (existing portion 154b) is arranged such that existing portion 154b and gap portion 154s are mixed within the area where the base portion 12a and the side plate fixing portion 36a overlap. For example, in the example of the inductor 100 shown in Figure 11, existing portion 154b is arranged to be scattered among the gap portion 154s. That is, multiple gap portions 154s are connected to each other. As an example, the existing portion 154b is 20 pieces / mm ２ These particles are scattered within the void portion 154s at the density described above. As a result, in the example of the inductor 100 shown in Figure 11, the present particles 154b and the void portion 154s are alternately arranged in any predetermined direction within the in-plane direction (XZ plane) of the side surface 12, namely the X-axis direction, the Z-axis direction, or an oblique direction intersecting both the X-axis and Z-axis directions.

[0054] Furthermore, in the example of the inductor 100 shown in Figure 12, multiple gap portions 154s are arranged so as to be scattered around one existing portion 154b. That is, the multiple existing portions 154b are connected to each other. As an example, there are 20 gap portions 154s / mm ２The present portion 154b is scattered at the above density. As a result, even in the example of the inductor 100 shown in Figure 12, the present portion 154b and the void portion 154s are alternately arranged in any predetermined direction within the in-plane direction (XZ plane) of the side surface 12, namely the X-axis direction, the Z-axis direction, or an oblique direction intersecting both the X-axis and Z-axis directions. Although the above has described the relationship between the scattered void portion 154s and the present portion 154b, the void portion 154s and the present portion 154b are not limited to scattered arrangements as long as they are alternately arranged in one or more predetermined directions. For example, the same effect can be obtained even if the void portion 154s and the present portion 154b are alternately arranged in a vertical stripe pattern in the X-axis direction, or in a horizontal stripe pattern in the Z-axis direction.

[0055] Here, Figure 13 shows a cross-sectional view of an example of inductor 100 mounting from the same viewpoint as Figure 4. Figure 13 also shows an enlarged view of a part of the said cross-sectional view. As shown in Figure 13, when mounting the inductor 100, the bottom surface 13 of the magnetic core 10 of the inductor 100 is mounted using solder 155 so that it faces the circuit board 151. Specifically, the electrode members 30 of the inductor 100 are electrically and physically connected to lands (not shown) formed on the circuit board 151 using solder 155. As shown in Figure 13, the solder 155 hardens by forming fillets, so that the inductor 100 is stably joined to the circuit board 151. As shown in the figure, the fillets of solder 155 wet and spread along the side plate 36 toward the top surface, and harden so as to sandwich the inductor 100 in the Y-axis direction.

[0056] The circuit board 151 is a so-called printed circuit board, in which conductive circuit patterns are formed inside and on the surface of a resin material. On the other hand, the magnetic core 10 is formed by compression molding of metallic magnetic powder and resin material, as described above. Therefore, because the magnetic core 10 and the circuit board 151 differ in materials and formation procedures, they have different coefficients of thermal expansion, and even if the same temperature load is applied, the amount of expansion and contraction will differ. In other words, the deformation of the magnetic core 10 may not be able to keep up with the deformation of the circuit board 151, causing stress to concentrate on the solder 155, which is the mounting part, and damage may occur to the solder 155 if thermal shock is continued. In other words, an inductor with a structure that is prone to stress concentration on the solder 155 has low mounting reliability.

[0057] On the other hand, in the inductor 100 of this embodiment, the area covered by the solder fillet 155 is a mixture of the portion 154b where adhesive 154 is present and the void portion 154s where adhesive 154 is absent. Furthermore, because the electrode member 30 made of foil material deforms easily, the void portion 154s can absorb a portion of the stress applied to the solder 155. Even with the void portion 154s provided, the strength of the adhesive fixing of the side plate 36 can be ensured by the portion 154b. Therefore, the inductor 100 properly fixes the side plate 36, and stress is less likely to concentrate on the solder 155, resulting in high mounting reliability. In other words, the inductor 100 can operate more appropriately.

[0058] The void portion 154s must exist in the area covered by the solder fillet 155. In this embodiment, the inductor 100 has a height of approximately 3.0 mm, so it is estimated that the void portion 154s extends to a height of approximately 0.3 mm from the bottom surface 13 of the fillet. Therefore, the lower region 162 of the adhesive 154, including the void portion 154s, is provided to span a height of 0.3 mm or more from the bottom surface 13 of the magnetic core 10, so as to correspond to at least the area below the top of the fillet. In other words, the lower region 162 of the adhesive 154, including the void portion 154s, is provided at a position higher than the reference height set to 0.3 mm or more from the bottom surface 13, and at a position lower than the reference height.

[0059] As an example, the height H1 of the lower region 162 of the adhesive 154 including the void portion 154s is 0.3 mm above the bottom surface 13 of the magnetic core 10, and the lower end is 0.0 mm above the bottom surface 13 of the magnetic core 10. The adhesive 154 of the lower region 162 may include continuous portions at its upper and lower ends, consisting only of the existing portion 154b other than the portion where the void portion 154s and the existing portion 154b are mixed. In this case, the height H1 of the lower region 162 of the adhesive 154 including the void portion 154s is 0.3 mm above the bottom surface 13 of the magnetic core 10, the lower end is 0.1 mm above the bottom surface 13 of the magnetic core 10, and a continuous portion may be provided at a position lower than 0.1 mm.

[0060] Furthermore, as shown in Figures 11 and 12, the void portions 154s and the present portions 154b are arranged regularly. That is, the two present portions 154b flanking the void portions 154s in a predetermined direction are arranged at a constant interval, and the two void portions 154s flanking the present portions 154b in a predetermined direction are arranged at a constant interval. In this way, the void portions 154s for stress absorption and the present portions 154b for ensuring adhesive strength are arranged without bias. As a result, it is possible to suppress localized unevenness in the stress absorption effect and localized unevenness in the effect of ensuring adhesive strength. In other words, the stress absorption effect and the effect of ensuring adhesive strength can be applied substantially uniformly regardless of location. Conversely, the void portions 154s and the present portions 154b may be arranged irregularly (with density gradients, etc.) depending on the location where the stress to be absorbed is applied.

[0061] In both Figure 11 and Figure 12, the adhesive 154 is scattered in the same way to form the inductor 100, but the amount of adhesive 154 used for scattering can be varied to create different inductors. Specifically, after scattering the adhesive 154, the side plate 36 is pressed against it and the adhesive 154 is allowed to harden. If the amount of adhesive 154 (and the pressure applied) is such that two or more adhesive 154 areas do not spread and come into contact, the inductor 100 shown in Figure 11 is formed. If the amount of adhesive 154 (and the pressure applied) is such that two or more adhesive 154 areas spread and come into contact, the inductor 100 shown in Figure 12 is formed.

[0062] Furthermore, as shown in Figure 13, in order to absorb the stress on the solder 155 with a width W2 of the gap portion 154s, it is necessary to specify that the electrode member 30 (side plate 36) sandwiched between the solder 155 and the gap portion 154s bends and deforms easily. For example, the width W2 of the gap portion 154s should be greater than the thickness T1 of the electrode member 30.

[0063] In the example of Figure 11, the width W2 of the void portion 154s can also be described as the distance between the two existing portions 154b that surround the void portion 154s. Depending on the combination of existing portions 154b selected, there are several possible lengths for the width W2 of the void portion 154s. Here, the width W2 of the void portion 154s is defined as the average value of the distances corresponding to all combinations of adjacent existing portions 154b. Alternatively, the width W2 of the void portion 154s may be the minimum distance among all combinations of adjacent existing portions 154b. Furthermore, in the example of Figure 12, if the shape of the scattered void portions 154s viewed from a direction perpendicular to the side surface 12 is approximately circular, the width W2 of the void portion 154s is the diameter of the scattered void portions 154s.

[0064] However, as shown in Figure 13, due to factors such as shrinkage when the adhesive 154 hardens, the distance between adjacent portions 154b of the void portion 154s changes as it moves away from the side surface 12 or side plate 36 in the cross-section of the layer formed by the adhesive 154. The width W2 of the void portion 154s is defined as corresponding to the longest distance in this cross-section, that is, the distance between the portions 154b at the center (the center in the thickness direction of the adhesive 154 layer) which is approximately equidistant from the side surface 12 and side plate 36. Therefore, the width W2 of the void portion 154s is greater than the contact width W1 of the void portion 154s with the side surface 12 and side plate 36. The contact width W1 is the width of the void portion 154s on the side surface 12 and side plate 36.

[0065] As described above, the void portion 154s contributes to the effect of absorbing stress on the solder 155, and the existing portion 154b contributes to ensuring the strength of the adhesive fixation. Therefore, if either the void portion 154s or the existing portion 154b is too large or too small compared to the other, it becomes difficult to achieve both of the above effects simultaneously. Figure 14 is a diagram illustrating the void ratio of the inductor according to the embodiment. In Figure 14, the void ratio of the adhesive surface shown on the horizontal axis is calculated by simulation using the ratio of the area of ​​the void portion 154s to the sum of the area of ​​the void portion 154s and the area of ​​the existing portion 154b in a plan view of the adhesive 154 in the lower region 162 from a direction perpendicular to the side plate 36, and the reduction rate of the maximum principal stress on the solder 155 is shown. In the figure, it is shown that the amount of stress absorbed on the solder 155 increases as it is higher in the vertical axis direction.

[0066] As shown in Figure 14, it is demonstrated that increasing the porosity allows for greater stress absorption on the solder 155. For example, if 2% is used as a baseline for stress absorption that is sufficiently effective beyond the error level, it can be seen that such an effect can be obtained if the porosity is 30% or higher. However, increasing the porosity directly means that the area ratio of the existing portion 154b, i.e., the adhesive area, decreases. In order to maintain a certain degree of adhesive strength in the lower region 162, the porosity should be 60% or less. In other words, from this simulation, it is best for the porosity to be between 30% and 60%.

[0067] As described above, in the inductor 100, the adhesive 154 is arranged in the lower region 162 to which the solder fillet 155 extends during mounting, such that the gap portion 154s and the present portion 154b are repeated in a predetermined direction. This allows the stress on the solder 155 to be absorbed by the gap portion 154s, while the present portion 154b maintains the strength of the adhesive fixing to the side plate 36. Therefore, the mounting reliability of the inductor 100 can be improved, and it can operate more appropriately.

[0068] The inductor 100 of this embodiment comprises a magnetic core 10 having a three-dimensional shape and containing a magnetic material, with a side surface 12, a bottom surface 13, and a top surface 14; a coil element 20 containing a metal material, having an embedded portion 21 embedded in the magnetic core 10, and a coil end 22 exposed from the magnetic core 10 and extending along the side surface of the magnetic core 10; and an electrode member 30 containing a metal material and joined 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 interior 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 arranged along the side surface 12 of the magnetic core 10 and a bottom plate 34 arranged along the bottom surface 13 of the magnetic core 10. The side plate 36 has a side plate fixing portion 36a that is fixed to the side surface 12 of the magnetic core 10, a side plate joining portion 36b that is joined to the coil end 22, and a side plate recess 36c that is connected to the side plate fixing portion 36a and the side plate joining portion 36b and recessed in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b.

[0069] In this way, since the side plate recess 36c, which is part of the electrode member 30, is recessed in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b, the position of the magnetic core 10 can be restricted using the side plate recess 36c. This improves the vibration resistance of the inductor 100.

[0070] [Manufacturing Method] Next, the manufacturing method of the inductor 100 described above will be explained with reference to Figures 15 to 17.

[0071] Figure 15 is a flowchart showing the manufacturing method of an inductor according to the embodiment. Figure 16 is a diagram showing the configuration in the manufacturing process of an inductor according to the embodiment. Figure 17 is a schematic diagram showing various processes applied to the side plate of the electrode member of the inductor according to the embodiment.

[0072] In the manufacturing method of the inductor 100, first, as shown in Figure 16(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 16(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 16(c), the end of the coil element 20 is press-formed so that it becomes flat (step S103). Next, as shown in Figure 16(d), the end of the coil element 20 is bent to follow the side surface 12 of the magnetic core 10 (step S104). This bending process positions the coil end 22 within the magnetic core recess 12b (see Figure 17(a)).

[0075] Next, as shown in Figure 16(e), adhesive 154 is applied to the two sides 12 of the magnetic core 10 (step S105). For example, the adhesive 154 is applied to the base 12a of the magnetic core 10 in the upper region 161 by printing or using a dispenser (see Figure 17(b)), and in the lower region 162, the adhesive 154 is applied by using a plate provided with multiple pores (approximately 50 to 100 μm in diameter) corresponding to the present portion 154b, using a short-pulse laser or the like, to allow a predetermined amount of adhesive 154 to seep out from the back surface of the pores to the surface, and then bringing the seeped-out adhesive 154 into contact with the plate.

[0076] Next, as shown in Figure 16(f), electrode members 30 are attached to each of the two sides 12 of the magnetic core 10 (step S106). In step S106, electrode members 30 that have been pre-bent and formed to have side plates 36 and bottom plates 34 are attached to the side plates 12 of the magnetic core 10. This fixes the side plates 36 of the electrode members 30 to the side plates 12 of the magnetic core 10 (see Figure 17(c)).

[0077] Next, as shown in Figure 16(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 17(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.

[0078] Next, as shown in Figure 16(h), a step (step S108) is performed in which the electrode member 30 and the coil end 22 are welded together by overlap joint laser welding. This joins the electrode member 30 to the coil end 22 (see Figure 17(e)). Through these steps, the inductor 100 is manufactured.

[0079] The method for manufacturing the inductor 100 according to this embodiment includes: an element formation step of forming a coil element 20 having a winding portion and a coil end 22; a magnetic core formation step of forming a magnetic core 10 in the form of a rectangular parallelepiped shape having a magnetic core recess 12b on its side surface 12, by embedding the winding portion so that the coil end 22 protrudes from the magnetic core recess 12b; a bending step of bending the coil end 22 so that the coil end 22 protruding from the magnetic core recess 12b is positioned within the magnetic core recess 12b; a fixing step of fixing the side plate 36 of the electrode member 30 to the side surface 12 of the magnetic core 10 so as to cover at least a part of the coil end 22 positioned within the magnetic core recess 12b; a recess formation step of pushing a part of the side plate 36 of the electrode member 30 into the magnetic core recess 12b to form a side plate recess 36c; and a joining step of joining the electrode member 30 to the coil end 22.

[0080] In this way, by recessing the side plate recess 36c, which is part of the electrode member 30, in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b, an inductor 100 can be manufactured in which the position of the magnetic core 10 can be restricted using the side plate recess 36c. This improves the vibration resistance of the inductor 100.

[0081] [Differences from Comparative Examples] The effects of the inductor according to this embodiment will be explained with reference to the comparative examples. Below, the advantages of forming the electrode member 30 from a copper-based metal foil with a thickness of less than 100 μm will be explained. Note that Comparative Example 1 shown below is prior art, but Comparative Examples 2 and 3 are examples presented for comparison with this embodiment and are not prior art.

[0082] Figure 18 is a schematic diagram showing the magnetic core, coil ends, and electrode members of the inductor of Comparative Example 1.

[0083] The electrode member 30x of the inductor 100x in Comparative Example 1 is flat and does not have a side plate recess like the electrode member 30 of the inductor 100 in the embodiment. In the inductor 100x of Comparative Example 1, the flat electrode member 30x is bonded to the magnetic core 10, but with this configuration it is difficult to further improve vibration resistance.

[0084] Figure 19 is a schematic diagram showing the magnetic core, coil ends, and electrode members of the inductor of Comparative Example 2.

[0085] Comparative Example 2 shows an example in which the thickness T1x of the electrode member 30x is 150 μm. In Comparative Example 2, after bonding the side plate 36x of the electrode member 30x to the side surface 12 of the magnetic core 10, a part of the side plate 36x of the electrode member 30x is pressed in to form a concave side plate recess 36cx. However, the side plate 36x with a thickness T1x of 150 μm has higher rigidity and lower flexibility than the side plate 36 of the metal foil (in this embodiment) with a thickness of 50 μm. Therefore, in Comparative Example 2, when a part of the side plate 36x is pressed in starting from the corner mx of the magnetic core 10 to form the side plate recess 36cx, the pressing force is also transmitted to the side plate fixing part 36ax, and there is a risk that the adhesion between the side plate fixing part 36ax and the side surface 12 will come undone. Also, in Comparative Example 2, when a part of the side plate 36x is pressed in, the coil end 22 may be deformed, and there is a risk that laser welding in the subsequent process cannot be performed stably.

[0086] Figure 20 is a schematic diagram showing the magnetic core, coil ends, and electrode members of the inductor of Comparative Example 3.

[0087] Comparative Example 3 shows an example in which the side plate recess 36cx is formed before attaching the electrode member 30x to the side surface 12 of the magnetic core 10, and the side plate 36x with the side plate recess 36cx formed therein is attached to the side surface of the magnetic core 10. However, when fitting the pre-formed side plate recess 36cx into the magnetic core recess 12b, a clearance is required between the corner mx and the bent portion nx to insert the side plate recess 36cx. Therefore, in Comparative Example 3, a clearance is created between the corner mx and the bent portion nx, making it difficult to further improve vibration resistance. In addition, in Comparative Example 3, due to variations in the thickness of the coil end 22 or the thickness of the adhesive, a gap may be created between the outer surface 22f1x of the coil end 22 and the side plate joint 36bx, which may make it difficult to perform laser welding stably in subsequent processes.

[0088] In contrast, in the inductor 100 of this embodiment, the electrode member 30 is made of copper-based metal foil with a thickness of less than 100 μm. Therefore, a side plate recess 36c can be easily formed by plastically deforming a part of the side plate 36 starting from the corner of the boundary between the side surface 12 of the magnetic core 10 and the magnetic core recess 12b. With this configuration, for example, when the inductor 100 is subjected to lateral and vertical vibrations, the side plate recess 36c acts to catch on the magnetic core recess 12b, etc. This improves the vibration resistance of the inductor 100.

[0089] Furthermore, the electrode member 30 is made of copper-based metal foil with a thickness of less than 100 μm, and has lower rigidity and higher flexibility than the coil end 22, so that it can form the side plate recess 36c while suppressing damage to the coil end 22. In addition, good contact can be maintained between the outer surface 22f1 of the coil end 22 and the side plate joint 36b, allowing for stable laser welding in subsequent processes.

[0090] [Modified Embodiment] An inductor according to a modified embodiment will be described with reference to Figure 21. In this modified embodiment, an example will be described in which the magnetic core recess 12b is configured by a single step.

[0091] Figure 21 is a perspective view of an inductor according to a modified example of the embodiment.

[0092] As shown in Figure 21, the inductor 100 according to a modified embodiment comprises a magnetic core 10, a coil element 20, and an electrode member 30. The configuration of the coil element 20 in the modified embodiment is the same as in the embodiment.

[0093] In the modified version, the magnetic core 10 differs from the embodiment in that the magnetic core recess 12b has a stepped shape. The magnetic core recess 12b in the modified version is a single step that drops into the interior of the magnetic core 10, starting from the base 12a.

[0094] 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. In this modified example, the base 12a is provided on the bottom surface 13 side of the coil end 22.

[0095] The magnetic core recess 12b has an opening on the top surface 14 side. The magnetic core recess 12b also extends to each of the two sides 11 of the magnetic core 10 and reaches both sides 11, and the magnetic core recess 12b has an opening on both sides 11. In the modified example, the magnetic core recess 12b is composed of one inner bottom surface 12b1 and one inner wall surface 12b2. The coil end 22 of the coil element 20 is placed in the magnetic core recess 12b.

[0096] The electrode member 30 is composed of a side plate 36 and a bottom plate 34.

[0097] The side plate 36 is a portion provided to correspond to the side surface 12 of the magnetic core 10 and to be provided along the side surface 12. The side plate 36 is positioned to overlap the base 12a and the coil end 22 of the side surface 12 of the magnetic core 10.

[0098] 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 the part that is fixed to the side surface 12 of the magnetic core 10. The side plate joining portion 36b is the part that is joined to the coil end 22.

[0099] In the modified example, 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, is in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b. The side plate recess 36c is formed 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 shaped to conform 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 to a part of the side plate 36 in a region different from the side plate fixing portion 36a and the side plate joining portion 36b, and pushing a part of the side plate 36 in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b.

[0100] The side plate recess 36c has 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 on the inner bottom surface 12b1 side of the magnetic core recess 12b, rather than the side surface 12 and the outer end surface 22f1 of the coil end 22. The inner wall portion 36c2 has an inclined surface.

[0101] The coil end 22 has two second corners m2 located at the boundary between the outer end surface 22f1 and the side surface 22s of the end. The second corners m2 are formed along the extension direction E22 of the coil end 22. The side plate 36 of the electrode member 30 has a second bent portion n2 at the boundary between the side plate joint 36b and the side plate recess 36c. The second bent portion n2 abuts against the second corner so as to cover the second corner m2. The side plate recess 36c is recessed in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b, starting from the second bent portion n2.

[0102] The two second corner portions m2 are arranged in a direction along the outer surface 22f1 of the end and perpendicular to the extension direction E22 of the coil end portion 22, that is, along the X-axis direction. Each of the two second bent portions n2 is located diagonally outside the two second corner portions m2 and abuts against 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 with respect to the electrode member 30 in the X-axis direction. As a result, the vibration resistance of the inductor 100 is improved.

[0103] The first corner portion m1 is located on the bottom surface 13 side 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. 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.

[0104] 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.

[0105] In this modified example, the side plate recess 36c, which is part of the electrode member 30, is recessed in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b, so that the position of the magnetic core 10 can be restricted using the side plate recess 36c. This improves the vibration resistance of the inductor 100.

[0106] (Summary) An example of an inductor 100 according to one embodiment of the present disclosure is given below.

[0107] The inductor 100 of Example 1 includes a magnetic core 10 which is a three-dimensional shape having sides 11 and 12, a top surface 14 and a bottom surface 13 which faces the circuit board 151 when mounted on the circuit board 151, a coil element 20 which includes a metal material and has an embedded portion 21 embedded in the magnetic core 10 and a coil end 22 which is exposed from the magnetic core 10 and extends along the side surface 12 of the magnetic core 10, a side plate joining portion 36b which includes a metal material and is joined to the coil end 22, and a side plate fixing portion 36a which is fixed to the side surface 12 of the magnetic core 10. The electrode member comprises an electrode member less than 100 μm thick, including a side plate 36 arranged along the side surface 12 of the magnetic core 10, and an adhesive 154 for adhesively fixing the side plate fixing portion 36a to the side surface 12 of the magnetic core 10. The adhesive 154 has a region (lower region 162) in which a portion 154b where the adhesive 154 exists between the side surface 12 of the magnetic core 10 and the side plate 36, and a gap portion 154s where the adhesive 154 does not exist between the side surface 12 of the magnetic core 10 and the side plate 36 are arranged to alternately repeat in a predetermined direction parallel to the side surface 12.

[0108] Thus, the inductor 100 includes a region in which air gaps 154s and present portions 154b are repeatedly arranged. In this region, when solder 155 is used for mounting to the circuit board 151, a portion of the stress on the solder 155 caused by the difference in configuration between the circuit board 151 and the magnetic core 10 can be absorbed by the air gaps 154s. In addition, the adhesive 154 of the present portion 154b can act to bond and fix the side plate 36 (side plate fixing portion 36a) to the side surface 12 (base portion 12a), so that the stress on the solder 155 is absorbed by the air gaps 154s while the strength of the bonded fixing of the side plate 36 can be maintained by the present portion 154b. Therefore, the inductor 100 can be made more reliable to mount and can operate more properly.

[0109] The inductor 100 of Example 2 is the inductor described in Example 1, wherein the side surface 12 of the magnetic core 10 is provided with a magnetic core recess 12b that is recessed toward the interior of the magnetic core 10, the coil end 22 protrudes from the magnetic core recess 12b and extends in the extending direction E22 along the inner bottom surface 12b1 of the magnetic core recess 12b, and the side plate 36 has a side plate recess 36c that is connected to the side plate fixing portion 36a and the side plate joining portion 36b and is recessed toward the inner bottom surface 12b1 of the magnetic core recess 12b.

[0110] In this way, since the side plate recess 36c, which is part of the electrode member 30, is recessed in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b, the position of the magnetic core 10 can be restricted using the side plate recess 36c. This improves the vibration resistance of the inductor 100.

[0111] The inductor 100 in Example 3 is the inductor described in Example 1 or Example 2, and the adhesive 154 has 20 pieces / mm of one of the existing portion 154b and the gap portion 154s relative to the other in the region. ２ They are arranged in a scattered manner with a certain density.

[0112] In this way, one of the existing portion 154b and the gap portion 154s is set to 20 units / mm relative to the other. ２ By distributing them at a certain density, the stress on the solder 155 is absorbed by the void portion 154s, while the present portion 154b maintains the strength of the adhesive fixing of the side plate 36.

[0113] The inductor 100 in Example 4 is the inductor described in Example 3, and the adhesive 154 is arranged such that air gaps 154s are scattered around the existing portion 154b in the region.

[0114] In this way, by distributing the void portions 154s relative to the existing portions 154b, the stress on the solder 155 can be absorbed by the void portions 154s, while the strength of the adhesive fixing of the side plate 36 can be maintained by the existing portions 154b.

[0115] The inductor 100 in Example 5 is the inductor described in Example 3, and the adhesive 154 is arranged in the region such that its present portion 154b is scattered with respect to the void portion 154s.

[0116] In this way, by distributing the existing portions 154b in relation to the void portions 154s, the stress applied to the solder 155 can be absorbed by the void portions 154s, while the strength of the adhesive fixing of the side plate 36 can also be maintained by the existing portions 154b.

[0117] The inductor 100 in Example 6 is an inductor described in any of Examples 1 to 5, and in a plan view taken from a direction perpendicular to the side plate 36, the ratio of the area of ​​the gap portion 154s to the sum of the existing portion 154b and the gap portion 154s in the region is selected from the range of 30% or more and 60% or less.

[0118] In this way, the stress on the solder 155 can be reduced (absorbed) by at least 2%, and the adhesive fixing strength of the side plate 36 can be maintained at 40% or more of the fixing strength when the entire surface is bonded due to the presence of portion 154b.

[0119] The inductor 100 in Example 7 is an inductor described in any of Examples 1 to 6, and the region is provided spanning a height of 0.3 mm or more from the bottom surface 13 of the magnetic core 10.

[0120] In this way, a lower region 162 including a gap portion 154s and an existing portion 154b can be provided at a position corresponding to the height of the solder fillet 155 when it is implemented.

[0121] The inductor 100 in Example 8 is the inductor described in any of Examples 1 to 7, wherein the width W2 of each air gap portion 154s is greater than the thickness T1 of the electrode member 30.

[0122] In this way, in order to absorb the stress of the solder 155, a gap portion 154s can be provided between the solder 155 and the gap portion 154s that can easily absorb the deflection of the electrode member 30.

[0123] The inductor 100 in Example 9 is an inductor described in any of Examples 1 to 8, wherein the width W2 of each air gap portion 154s is greater than the contact width W1 of the air gap portion 154s with the side surface 12 of the magnetic core 10.

[0124] In this way, a gap portion 154s with a width W2 that is larger than the ground contact width W1 can be provided.

[0125] Furthermore, the inductor 100 of the other example 1 includes a magnetic core 10 having a three-dimensional shape with a side surface 12, a bottom surface 13 and a top surface 14 and containing a magnetic material; a coil element 20 having a buried portion 21 embedded in the magnetic core 10 and a coil end 22 exposed from the magnetic core 10 and extending along the side surface 12 of the magnetic core 10; and an electrode member 30 made of a metal material and joined 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 interior 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 arranged along the side surface 12 of the magnetic core 10 and a bottom plate 34 arranged along the bottom surface 13 of the magnetic core 10. The side plate 36 has a side plate fixing portion 36a that is fixed to the side surface 12 of the magnetic core 10, a side plate joining portion 36b that is joined to the coil end 22, and a side plate recess 36c that is connected to the side plate fixing portion 36a and the side plate joining portion 36b and recessed in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b.

[0126] In this way, since the side plate recess 36c, which is part of the electrode member 30, is recessed in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b, the position of the magnetic core 10 can be restricted using the side plate recess 36c. This improves the vibration resistance of the inductor 100.

[0127] Furthermore, the inductor 100 in the alternative example 2 is the inductor described in alternative example 1, and the side plate recess 36c may be located between the inner wall surface 12b2 of the magnetic core recess 12b and the coil end 22.

[0128] With this configuration, the position of the magnetic core 10 and the coil end 22 can be restricted using the side plate recess 36c. This improves the vibration resistance of the inductor 100.

[0129] Furthermore, the inductor 100 in alternative example 3 is the inductor described in alternative example 1 or 2, and the side plate recess 36c may be 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.

[0130] With this configuration, the position of the magnetic core 10 can be restricted using the side plate recesses 36c located on both sides of the coil end 22. This improves the vibration resistance of the inductor 100.

[0131] Furthermore, the inductor 100 of alternative example 4 is an inductor described in any of alternative examples 1 to 3, wherein the magnetic core 10 has a first corner portion 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 side plate 36 has a first bent portion n1 that abuts against the first corner portion m1 so as to cover the first corner portion m1, and the side plate recess 36c may be recessed in the direction of the inner bottom surface 12b1 starting from the first bent portion n1.

[0132] With this configuration, the position of the first corner m1 can be restricted using the first bent portion n1. This restricts the position of the magnetic core 10 and improves the vibration resistance of the inductor 100.

[0133] Furthermore, the inductor 100 in alternative example 5 is the inductor described in alternative example 4, and the first bent portion n1 may be in contact with the first corner portion m1 via an adhesive.

[0134] With this configuration, the position of the first corner portion m1 can be restricted via the adhesive. This restricts the position of the magnetic core 10 and improves the vibration resistance of the inductor 100.

[0135] Furthermore, the inductor 100 in alternative example 6 is the inductor described in alternative example 4, wherein the magnetic core 10 has a plurality of first corners m1 in a direction along the side surface 12 of the magnetic core 10 and in a direction parallel to the bottom surface 13 of the magnetic core 10, and the side plate 36 has a plurality of first bent portions n1 corresponding to the plurality of first corners m1.

[0136] With this configuration, the positions of multiple first bends n1 can be controlled using multiple first corners m1. This allows the position of the magnetic core 10 to be controlled, thereby improving the vibration resistance of the inductor 100.

[0137] Furthermore, the inductor 100 of alternative example 7 is an inductor described in any of alternative examples 1 to 6, wherein the coil end 22 is flat and has an outer end surface 22f1 that contacts the side plate joint 36b, an outer end surface 22s that connects to the outer end surface 22f1, and a second corner m2 located at the boundary between the outer end surface 22f1 and the outer end surface 22s, the side plate 36 has a second bent portion n2 that abuts against the second corner m2 so as to cover the second corner m2, and the side plate recess 36c may be recessed in the direction of the inner bottom surface 12b1 starting from the second bent portion n2.

[0138] With this configuration, the position of the coil end 22 can be restricted using the second bent portion n2. This improves the vibration resistance of the inductor 100.

[0139] Furthermore, the inductor 100 of alternative example 8 is the inductor described in alternative example 7, and 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, the coil end 22 may have a plurality of second corners m2, and the side plate 36 may have a plurality of second bends n2 corresponding to the plurality of second corners m2.

[0140] With this configuration, the positions of multiple second corners m2 can be restricted using multiple second bends n2. This restricts the position of the coil end 22 and improves the vibration resistance of the inductor 100.

[0141] Furthermore, the inductor 100 in alternative example 9 is an inductor described in any of alternative examples 1 to 8, and the depth dp2 of the side plate recess 36c may be 0.3 times or more and 0.9 times or less of the depth dp1 of the magnetic core recess 12b.

[0142] According to this, the position of the magnetic core 10 can be reliably controlled using the recess 36c of the side plate. This improves the vibration resistance of the inductor 100.

[0143] Furthermore, the inductor 100 in alternative example 10 is the inductor described in any of alternative examples 1 to 8, and the depth dp2 of the side plate recess 36c may be 1 / 2 or more of the thickness T1 of the electrode member 30.

[0144] According to this, the position of the magnetic core 10 can be reliably controlled using the plastically deformed side plate recess 36c. This improves the vibration resistance of the inductor 100.

[0145] The inductor 100 of this disclosure may be formed by the inductor manufacturing method described below. For example, the manufacturing method of the inductor 100 includes the steps of forming a molded body (a magnetic core with a coil embedded in it) in which the coil end 22 of the coil element 20 protrudes from the magnetic core recess 12b on the side surface 12 of the magnetic core 10 in which the winding portion of the coil element 20 is embedded and is placed in the magnetic core recess 12b; fixing the side plate 36 of the electrode member 30 to the side surface 12 of the magnetic core 10 so as to cover at least a part of the coil end 22 placed in the magnetic core recess 12b; recess forming step to push a part of the side plate 36 of the electrode member 30 into the magnetic core recess 12b to form a side plate recess 36c; and joining step to join the electrode member 30 to the coil end 22.

[0146] In this way, by recessing the side plate recess 36c, which is part of the electrode member 30, in the direction of the inner bottom surface 12b1 of the magnetic core recess 12b, an inductor 100 can be manufactured in which the position of the magnetic core 10 can be restricted using the side plate recess 36c. This improves the vibration resistance of the inductor 100.

[0147] Furthermore, an inductor may be realized by combining any of the inductors from Examples 1 to 9 shown above with the inductors from Other Examples 1 to 10.

[0148] (Other Embodiments, etc.) Although the inductors relating to the embodiments, etc. of this disclosure have been described above, this disclosure is not limited to these embodiments.

[0149] 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.

[0150] Furthermore, this disclosure is not limited to this embodiment. Without departing from the spirit of this disclosure, various modifications to this embodiment 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.

[0151] The inductor relating to this disclosure is useful as an inductor for use in various devices and equipment.

[0152] 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 22f1 Outer end surface 22f2 Inner end surface 22s Side end surface 30 Electrode member 34 Bottom plate 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 40 Joining area 80 Pressing jig 100 Inductor 151 Circuit board 154 Adhesive 154a Main part 154b Existing part 154s Gap part 155 Solder m1 First corner m2 Second corner n1 First bend n2 Second bend dp1, dp2 Depth H1 Height T1 Thickness W1, W2 Width

Claims

1. An inductor comprising: a magnetic core having a three-dimensional shape including a magnetic material and having sides, a top surface and a bottom surface facing the circuit board when mounted on the circuit board; 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 side surface of the magnetic core; an electrode member less than 100 μm thick including a side plate, which includes a metal material and has a side plate joining portion joined to the coil end and a side plate fixing portion fixed to the side surface of the magnetic core, and is arranged along the side surface of the magnetic core; and an adhesive for bonding and fixing the side plate fixing portion to the side surface of the magnetic core, wherein the adhesive has regions in which a plurality of portions where the adhesive exists between the side surface of the magnetic core and the side plate and a plurality of void portions where the adhesive does not exist between the side surface of the magnetic core and the side plate are arranged to alternately repeat in a predetermined direction parallel to the side surface.

2. The inductor according to claim 1, wherein the side surface of the magnetic core is provided with a magnetic core recess that 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, and the side plate has a side plate recess that is connected to the side plate fixing portion and the side plate joining portion and is recessed toward the inner bottom surface of the magnetic core recess.

3. In the aforementioned region, the adhesive has a density of 20 units / mm between the plurality of existing portions and the plurality of void portions relative to the other. ２ The inductor according to claim 1, which is arranged to be scattered at a density of [value].

4. The inductor according to claim 3, wherein the adhesive is arranged in the region such that the plurality of void portions are scattered with respect to the plurality of existing portions.

5. The inductor according to claim 3, wherein the adhesive is arranged in the region such that the plurality of present portions are scattered with respect to the plurality of void portions.

6. In a plan view taken from a direction perpendicular to the side plate, the ratio of the area of ​​the plurality of gap portions to the sum of the plurality of existing portions and the plurality of gap portions within the region is selected from the range of 30% or more and 60% or less, as described in claim 1.

7. The inductor according to claim 1, wherein the region is provided across a height position of 0.3 mm or more from the bottom surface of the magnetic core.

8. The inductor according to claim 1, wherein the width of each of the plurality of gap portions is greater than the thickness of the electrode member.

9. The inductor according to claim 1, wherein the width of each of the plurality of gap portions is greater than the contact width of the plurality of gap portions with the side surface of the magnetic core.

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