Inductor and method for manufacturing inductor

Abstract

Provided are: an inductor that enables shape miniaturization and high-density mounting while reducing magnetic coupling between coils; and a method for manufacturing the inductor. Inductors 1A, 1B according to the present disclosure each comprise: an element body 10 containing metal magnetic particles DP; and a first coil 21 and second coil 22 disposed in the element body 10. The first coil 21 and second coil 22 are disposed adjacent to each other in a direction intersecting the winding axes. In the plan view as viewed from the top surface of the element body 10, the shape of a first winding part 51 of the first coil 21 is symmetrical to the shape of a second winding part 52 of the second coil 22. In the plan view as viewed from the top surface of the element body 10, the first winding part 51 of the first coil 21 and the second winding part 52 of the second coil 22 partially overlap.

Description

Inductor and Method for Manufacturing Inductor

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

[0002] Patent Document 1 discloses a laminated coil array for a DC-DC converter in which a first coil and a second coil are stacked and incorporated in a body.

[0003] Japanese Patent Application Laid-Open No. 2020-61415

[0004] In the laminated coil array for a DC-DC converter described in Patent Document 1, the first coil and the second coil are stacked and incorporated, and the magnetic coupling between the coils is relatively strong. Depending on the user, an inductor with a weak magnetic coupling between the coils may be preferred. In that case, it has been desired to enable miniaturization of the shape and high-density mounting at the user's site.

[0005] In view of such problems, the main object of the present disclosure is to provide an inductor and a method for manufacturing an inductor that enable miniaturization of the shape and high-density mounting while reducing the magnetic coupling between the coils.

[0006] The inductor of the present disclosure includes: a body containing metal magnetic particles; a first coil and a second coil disposed in the body; the first coil and the second coil are disposed adjacent to each other in a direction intersecting the winding axis; in a plan view seen from the upper surface of the body, the shape of the winding portion of the first coil is in a symmetric relationship with the shape of the winding portion of the second coil; in a plan view seen from the upper surface of the body, the winding portion of the first coil and the winding portion of the second coil partially overlap.

[0007] The method for manufacturing an inductor according to the present disclosure is a method for manufacturing the above-described inductor, comprising: a base body forming step of forming a base body by laminating a magnetic layer containing metallic magnetic particles, coil conductors corresponding to the winding portion of the first coil and the winding portion of the second coil, and lead conductors drawn out from the winding portion of the first coil and the winding portion of the second coil; a grinding step of grinding one main surface and the other main surface of the base body; and an electrode forming step of forming electrodes on one main surface and the other main surface of the base body.

[0008] The inductor and inductor manufacturing method described herein provide an inductor and an inductor manufacturing method that enable miniaturization of the shape and high-density mounting while reducing the magnetic coupling between coils.

[0009] Figure 1 is a perspective view of an inductor according to the first embodiment of this disclosure. Figure 2A is a front perspective view of an inductor according to the first embodiment of this disclosure. Figure 2B is a plan perspective view of an inductor according to the first embodiment of this disclosure. Figure 2C is an enlarged cross-sectional view of the portion enclosed by the dashed line in Figure 2A. Figure 3 is an exploded perspective view of an inductor according to the first embodiment of this disclosure. Figure 4 is a perspective view of an inductor according to a modified example of the first embodiment of this disclosure. Figure 5 is a perspective view of an inductor according to the second embodiment of this disclosure. Figure 6 is an exploded perspective view of an inductor according to the second embodiment of this disclosure. Figure 7 is a perspective view of an inductor according to a modified example of the second embodiment of this disclosure. Figure 8 is a manufacturing flow chart of a method for manufacturing the inductor of this disclosure.

[0010] The inductors of this disclosure are described below. However, this disclosure is not limited to the configurations described below and may be modified as appropriate without departing from the gist of this disclosure. Furthermore, combinations of several of the preferred configurations described below also constitute this disclosure.

[0011] The inductor of this disclosure can be used, for example, as a choke coil in a DC-DC converter. However, the inductor of this disclosure can also be applied to applications other than choke coils.

[0012] In this specification, terms describing relationships between elements (e.g., "parallel," "orthogonal," etc.) and terms describing the shape of elements mean not only strictly accurate embodiments but also substantially equivalent ranges, such as ranges with differences of a few percent. In this specification, the direction in which the magnetic material layers and coil conductors constituting the base body are stacked is referred to as the "stacking direction" or "height direction." In this specification, "plan view" means viewing from the first main surface 11 side of the base body 10 (see Figure 1), that is, viewing along the -Z direction in Figure 1.

[0013] The drawings shown below are schematic representations, and their dimensions, aspect ratios, and scales may differ from those of the actual product.

[0014] <Inductor of the First Embodiment> First, an embodiment of the inductor of the present disclosure will be described with reference to Figures 1 to 3. Figure 1 is a perspective view of the inductor according to the first embodiment of the present disclosure, Figure 2A is a front perspective view of the inductor according to the first embodiment of the present disclosure, Figure 2B is a plan perspective view of the inductor according to the first embodiment of the present disclosure, Figure 2C is an enlarged cross-sectional view of the dashed line portion of Figure 2A, and Figure 3 is an exploded perspective view of the inductor according to the first embodiment of the present disclosure.

[0015] The inductor 1A of the first embodiment comprises a base body 10, a first coil 21, and a second coil 22. Each component will be described in detail below.

[0016] -Basic Body- The basic body 10 is, for example, a hexahedron shape having six faces. As an example, it may be a rectangular prism shape or a roughly rectangular prism shape. The corners and edges of the basic body 10 may be rounded. The corners are the parts where three faces of the basic body 10 intersect, and the edges are the parts where two faces of the basic body 10 intersect.

[0017] Figure 1 shows the length, width, and height directions of the inductor 1A and the base body 10 as the X, Y, and Z directions, respectively. The length direction X, the width direction Y, and the height direction Z are orthogonal to each other.

[0018] The base body 10 shown in Figure 1 has a first main surface 11 and a second main surface 12 that are opposite to the height direction Z, a first end surface 13 and a second end surface 14 that are opposite to the length direction X, and a first side surface 15 and a second side surface 16 that are opposite to the width direction Y.

[0019] In the example shown in Figure 1, the first one-sided lead conductor 31a and the second one-sided lead conductor 32a are provided on the first main surface 11 of the base body 10, respectively, on the virtual diagonal L1. In this specification, the virtual diagonal refers to a virtual line connecting the diagonals of the first main surface 11. Also, in the example shown in Figure 1, when viewed from above the base body 10 in each of the stacking groups described later, the first one-sided lead conductor 31a and the second one-sided lead conductor 32a on the first main surface 11 side of the base body 10 (for example, the first one-sided lead conductor 31a and the second one-sided lead conductor 32a of stacking group G1 (see Figure 3)) are formed larger than the first one-sided lead conductor 31a and the second one-sided lead conductor 32a on the inside side of the base body 10 (for example, the first one-sided lead conductor 31a and the second one-sided lead conductor 32a of stacking group G2 (see Figure 3)). Furthermore, the first one-sided lead conductor 31a and the second one-sided lead conductor 32a on the first main surface 11 side of the base body 10 (for example, the first one-sided lead conductor 31a and the second one-sided lead conductor 32a of the laminated group G1 (see Figure 3)) are formed in a rectangular shape when viewed from above the base body 10. Note that the size of the first one-sided lead conductor 31a and the second one-sided lead conductor 32a on the first main surface 11 side of the base body 10 is not limited to the above-described embodiment, and the size may be the same on the first main surface 11 side (for example, laminated group G1 in Figure 3) and the interior side (for example, laminated group G2 in Figure 3).

[0020] Furthermore, on the second main surface 12 of the base body 10, the first other-direction conductor 31b and the second other-direction conductor 32b are provided on a virtual diagonal L2 that intersects with the virtual diagonal L1 in planar perspective. In the example shown in Figure 1, when viewed from above the base body 10 in each of the stacking groups described later, the first other-direction conductor 31b and the second other-direction conductor 32b on the second main surface 12 side of the base body 10 (for example, the first other-direction conductor 31b and the second other-direction conductor 32b of stacking group G7 (see Figure 3)) are formed to be larger than the first other-direction conductor 31b and the second other-direction conductor 32b on the inside side of the base body 10 (for example, the first other-direction conductor 31b and the second other-direction conductor 32b of stacking group G6 (see Figure 3)). Furthermore, the first other-direction conductor 31b and the second other-direction conductor 32b on the first main surface 11 side of the base body 10 (for example, the first other-direction conductor 31b and the second other-direction conductor 32b of the laminated group G7 (see Figure 3)) are formed in a rectangular shape when viewed from above the base body 10. Note that the size of the first other-direction conductor 31b and the second other-direction conductor 32b on the second main surface 12 side of the base body 10 is not limited to the above-described embodiment, and the size may be the same on the second main surface 12 side (for example, laminated group G7 in Figure 3) and the interior side (for example, laminated group G6 in Figure 3).

[0021] Furthermore, the first one-way lead conductor 31a is electrically connected to the first one-way conductor 41a, the second one-way lead conductor 32a is electrically connected to the second one-way conductor 42a, the first other-way lead conductor 31b is electrically connected to the first other-way conductor 41b, and the second other-way lead conductor 32b is electrically connected to the second other-way conductor 42b.

[0022] Figure 3 is a schematic exploded perspective view showing an example of the internal structure of an inductor according to the first embodiment of this disclosure. As shown in Figure 3, the base body 10 is constructed by stacking multiple magnetic material layers ML in the height direction. Inside the base body 10 are a first coil 21 having a first winding portion 51, which will be described later, and a second coil 22 having a second winding portion 52. In this embodiment, as shown in Figure 3, the base body 10 is constructed by stacking stacking groups G1 to G7. The boundaries between each layer of the stacking structure of the base body 10 may disappear. Also, the thicknesses of each stacking group G1 to G7 may be different from each other. The stacking groups G1 to G7 will be described in detail below.

[0023] (Laminated group G1) Laminated group G1 has a magnetic layer ML and may constitute the first main surface 11 of the base body 10. A first one-way lead conductor 31a and a second one-way lead conductor 32a are provided on the virtual diagonal L1 of the magnetic layer ML.

[0024] (Laminated group G2) Laminated group G2 comprises a magnetic layer ML, a first one-way drawn conductor 31a, and a second one-way drawn conductor 32a.

[0025] The first one-way lead conductor 31a is electrically connected to the first one-way lead conductor 31a of the aforementioned laminated group G1, and is electrically connected to the first one-way lead conductor 31a of the laminated group G3, which will be described later. The planar area of ​​the first one-way lead conductor 31a of laminated group G1 may be designed to be larger than the planar area of ​​the first one-way lead conductor 31a of laminated group G2.

[0026] The second one-way lead conductor 32a is electrically connected to the second one-way lead conductor 32a of the aforementioned laminated group G1, and is electrically connected to one end of the second winding portion 52 of the laminated group G3, which will be described later. The planar area of ​​the second one-way lead conductor 32a of the laminated group G1 may be designed to be larger than the planar area of ​​the second one-way lead conductor 32a of the laminated group G2.

[0027] The first one-sided lead conductor 31a and the second one-sided lead conductor 32a in this embodiment may both be cylindrical in shape. However, the shape of the first one-sided lead conductor 31a and the second one-sided lead conductor 32a is not limited to a cylindrical shape, and may also be a prism shape.

[0028] (Laminated group G3) Laminated group G3 comprises a magnetic layer ML, a first one-way lead conductor 31a, and a second winding portion 52.

[0029] The first one-way lead conductor 31a is electrically connected to the first one-way lead conductor 31a of the aforementioned laminated group G2, and is electrically connected to the first one-way lead conductor 31a of the laminated group G4, which will be described later. The planar area of ​​the first one-way lead conductor 31a of laminated group G3 may be approximately the same as the planar area of ​​the first one-way lead conductor 31a of laminated group G2.

[0030] The second winding section 52 is provided to be wound around the winding axis O2. The winding axis O2 may be located in the Y direction between the second one-way lead conductor 32a of the aforementioned laminated group G2 and the second other-way lead conductor 32b of the later-described laminated group G4 in a plan view. In Figure 3, which shows an example, the second winding section 52 is formed in less than one turn and has a curved shape such that it has a curved apex P2 on the inside of the base body 10. One end of the second winding section 52 is electrically connected to the second one-way lead conductor 32a of the aforementioned laminated group G2, and the other end of the second winding section 52 is electrically connected to the second other-way lead conductor 32b of the later-described laminated group G4.

[0031] (Laminated group G4) Laminated group G4 comprises a magnetic layer ML, a first one-way lead conductor 31a, and a second other-way lead conductor 32b.

[0032] The first one-way lead conductor 31a is electrically connected to the first one-way lead conductor 31a of the aforementioned laminated group G3, and is electrically connected to one end of the first winding portion 51 of the laminated group G5, which will be described later. The planar area of ​​the first one-way lead conductor 31a of the laminated group G4 may be approximately the same as the planar area of ​​the first one-way lead conductor 31a of the laminated group G3.

[0033] The second other lead conductor 32b is electrically connected to the other end of the second winding portion 52 of the aforementioned laminated group G3, and is electrically connected to the second other lead conductor 32b of the laminated group G5 described later. In Figure 3, which shows an example, the second other lead conductor 32b and the first one lead conductor 31a may be aligned on the +Y direction side of the element 10 in a plan view.

[0034] In this embodiment, both the first one-way lead conductor 31a and the second other-way lead conductor 32b may be cylindrical in shape. However, the shape of the first one-way lead conductor 31a and the second other-way lead conductor 32b is not limited to a cylindrical shape, and they may also be prism-shaped.

[0035] (Laminated group G5) Laminated group G5 comprises a magnetic layer ML, a first winding portion 51, and a second other leading conductor 32b.

[0036] The first winding section 51 is provided to be wound around a winding axis O1. The winding axis O1 may be provided to be wound around a winding axis O1 located in the Y direction between the first one-way lead conductor 31a of the aforementioned laminated group G4 and the first other-way lead conductor 31b of the later-described laminated group G6 in a plan view. In Figure 3, which shows an example, the first winding section 51 is formed in less than one turn and has a curved shape such that it has a curved apex P1 on the inside of the base body 10. One end of the first winding section 51 is electrically connected to the first one-way lead conductor 31a of the aforementioned laminated group G4, and the other end of the first winding section 51 is electrically connected to the first other-way lead conductor 31b of the later-described laminated group G6.

[0037] The second other lead conductor 32b is electrically connected to the second other lead conductor 32b of the aforementioned laminated group G4, and is electrically connected to the second other lead conductor 32b of the laminated group G6 described later.

[0038] (Laminated group G6) Laminated group G6 comprises a magnetic layer ML, a first other-leaded conductor 31b, and a second other-leaded conductor 32b.

[0039] The first other lead conductor 31b is electrically connected to the other end of the first winding portion 51 of the aforementioned laminated group G5, and is electrically connected to the first other lead conductor 31b of the laminated group G7, which will be described later.

[0040] The second other lead conductor 32b is electrically connected to the second other lead conductor 32b of the aforementioned laminated group G5, and is electrically connected to the second other lead conductor 32b of the later-described laminated group G7.

[0041] The first other lead-out conductor 31b and the second other lead-out conductor 32b of this embodiment may both be cylindrical. Note that the shapes of the first other lead-out conductor 31b and the second other lead-out conductor 32b are not limited to cylindrical shapes, and may be prismatic shapes.

[0042] (Stacked group G7) The stacked group G7 has a magnetic layer ML and may constitute the second main surface 12 of the base body 10. Then, the first other lead-out conductor 31b and the second other lead-out conductor 32b may be provided on a virtual diagonal line L2 different from the virtual diagonal line L1 described in the above-mentioned stacked group G1. Note that the planar area of the first other lead-out conductor 31b of the stacked group G7 may be designed to be larger than the planar area of the first other lead-out conductor 31b of the stacked group G6, and the planar area of the second other lead-out conductor 32b of the stacked group G7 may be designed to be larger than the planar area of the second other lead-out conductor 32b of the stacked group G6.

[0043] As described above, the base body 10 of this embodiment includes stacked groups G1 to G7. Note that the stacked structure including the stacked groups G1 to G7 may be sequentially and repeatedly printed by screen printing or the like from the second main surface 12 side of the base body 10, or may be sequentially and repeatedly printed by screen printing or the like from the first main surface 11 side of the base body 10.

[0044] Additional elements regarding the base body 10 will be described. The magnetic layer ML may include metal magnetic particles DP made of a magnetic material (see FIG. 2C). The metal magnetic particles DP may contain Fe and / or Si. More specifically, they may be Fe particles or Fe alloy particles. Examples of the Fe alloy may include Fe—Si-based alloys, Fe—Si—Cr-based alloys, Fe—Si—Al-based alloys, Fe—Si—B—P—Cu—C-based alloys, Fe—Si—B—Nb—Cu-based alloys, and the like. Further, the metal magnetic particles DP may contain impurities such as Cr, Mn, Cu, Ni, P, S, or Co that are not intended in production.

[0045] The surface of the metal magnetic particles DP described above may be covered with an insulating oxide film OL (see Figure 2C). Covering the surface of the metal magnetic particles with an insulating oxide film OL increases the insulation between the metal magnetic particles DP. Methods for forming the insulating oxide film OL on the surface of the metal magnetic particles DP include the sol-gel method and the mechanochemical method. The materials constituting the insulating oxide film OL may be oxides of P, Si, zinc phosphate, or manganese phosphate. The insulating oxide film OL may also be an oxide film formed by the oxidation of the surface of the metal magnetic particles DP. The thickness of the insulating oxide film OL is preferably 1 nm to 50 nm, more preferably 1 nm to 30 nm, and even more preferably 1 nm to 20 nm. For example, a cross-section obtained by polishing an inductor sample can be photographed with a scanning electron microscope (SEM), and the thickness of the insulating oxide film OL covering the surface of the metal magnetic particles DP can be measured from the obtained SEM image.

[0046] The average particle size of the metallic magnetic particles DP in the magnetic layer ML is preferably 1 μm to 30 μm, more preferably 1 μm to 20 μm, and even more preferably 1 μm to 10 μm. The average particle size of the metallic magnetic particles DP in the magnetic layer ML can be measured by the procedure described below. A sample of the inductor is cut to obtain a sample cross-section. Specifically, a sample cross-section is obtained by cutting through the center of the base body 10 so as to be perpendicular to the first main surface 11, the second main surface 12, and the end face of the base body 10. Multiple regions (e.g., 130 μm × 100 μm) of the obtained cross-section are photographed with an SEM, and the obtained SEM images are analyzed using image analysis software (e.g., image analysis software WinROOF2021 (manufactured by Mitani Corporation)) to determine the equivalent circle diameter of the metallic magnetic particles DP. The average value of the obtained equivalent circle diameters is taken as the average particle size of the metallic magnetic particles DP.

[0047] At least one of one main surface (first main surface 11) and the other main surface (second main surface 12) of the base body 10 may be provided with a recess C from which the metal magnetic particles DP have been removed (see FIG. 2C). The formation of the recess C will be described in detail in the manufacturing method of the inductor described later, but it may be provided by etching the first main surface 11 and the second main surface 12 of the base body 10 in the removal process, so that the metal magnetic particles DP are removed. Thereby, the first main surface 11 and the second main surface 12 of the base body 10 are not exposed with the metal magnetic particles DP, and the inductor can be appropriately electrically mounted.

[0048] For the purpose of further improving the strength of the base body 10, the base body 10 may be impregnated with an insulating resin material after heat treatment of the base body 10. Specifically, the insulating resin material may penetrate into the interior of the base body 10. As an example of the resin for increasing the strength of the base body, an epoxy resin, a phenolic resin and / or a silicone resin may be used.

[0049] The base body 10 will be described in detail in the manufacturing method of the inductor described later, but the first main surface 11 and the second main surface 12 may be ground. Therefore, the surface roughness of the first main surface 11 and the second main surface 12 of the base body 10 (more specifically, the surface roughness of the first main surface 11 and the second main surface 12 in contact with the insulating coating IL (see FIG. 2C)) may be rougher than the surface roughness of the surfaces of the base body 10 other than the first main surface 11 and the second main surface 12 (for example, the first end surface 13, the second end surface 14, the first side surface 15 and the second side surface 16 in FIG. 1) (more specifically, the surface roughness of the first end surface 13, the second end surface 14, the first side surface 15 and the second side surface 16 in contact with the insulating coating IL).

[0050] -First Coil- The first coil 21 comprises a first winding portion 51 as described in the lamination group G5 above, a first one-way lead conductor 31a extending from one end of the first winding portion 51 along the +Z direction, a first one-way conductor 41a electrically connected to the first one-way lead conductor 31a, a first other lead conductor 31b extending from one end of the first winding portion 51 along the -Z direction, and a first other lead conductor 41b electrically connected to the first other lead conductor 31b. The planar area of ​​the first one-way conductor 41a and the first other lead conductor 41b may be smaller than the planar area of ​​the first one-way lead conductor 31a of lamination group G1 and the first other lead conductor 31b of lamination group G7. Furthermore, the first one-way conductor 41a and the first other lead conductor 41b may be formed by electroplating. The plating material may be Cu plating. Other examples include, but are not limited to, Ni-Sn, Ni-Au, Ni-Cu, and / or Cu-Ni-Au.

[0051] -Second Coil- The second coil 22 comprises a second winding portion 52 as described in the laminated group G3 above, a second one-way lead conductor 32a extending from one end of the second winding portion 52 along the +Z direction, a second one-way conductor 42a electrically connected to the second one-way lead conductor 32a, a second other-way lead conductor 32b extending from one end of the second winding portion 52 along the -Z direction, and a second other-way conductor 42b electrically connected to the second other-way lead conductor 32b. The planar area of ​​the second one-way conductor 42a and the second other-way conductor 42b may be smaller than the planar area of ​​the second one-way lead conductor 32a of laminated group G1 and the second other-way lead conductor 32b of laminated group G7. Furthermore, the second one-way conductor 42a and the second other-way conductor 42b may be formed by electroplating. The plating material may be Cu plating. Other materials include, but are not limited to, Ni-Sn, Ni-Au, Ni-Cu, and / or Cu-Ni-Au. The second coil 22 may have the same structure as the first coil 21 when inverted vertically.

[0052] The second coil 22 is positioned adjacent to the first coil 21 in a direction that intersects the direction along the winding axes O1 and O2 (i.e., the +Z direction in Figure 1) (i.e., the +X direction in Figure 1). As described above, the second coil 22 has the same structure as the first coil 21 when it is inverted vertically and rotated 180 degrees around the winding axis O1. Therefore, in a plan view, the shape of the second winding portion 52 of the second coil 22 is symmetrical to the shape of the first winding portion 51 of the first coil 21. In this specification, "symmetrical shape" means that when one object (the first coil) is inverted vertically and rotated 180 degrees around the winding axis, it becomes the same shape as the other object (the second coil).

[0053] Furthermore, the second winding portion 52 of the second coil 22 partially overlaps with the first winding portion 51 of the first coil 21 in a plan view. More specifically, at least the curved apex P2 of the second winding portion 52 overlaps with the first winding portion 51 in a plan view, and the curved apex P1 of the first winding portion 51 overlaps with the second winding portion 52 in a plan view. In this way, the partial overlap of the first winding portion 51 of the first coil 21 and the second winding portion 52 of the second coil 22 reduces the magnetic coupling between the coils compared to inductors where the first and second coils are stacked and built into a base body, as in the conventional technology. Furthermore, because the first winding portion 51 of the first coil 21 and the second winding portion 52 of the second coil 22 partially overlap in a plan view, it is possible to miniaturize the shape and achieve high-density mounting in the direction in which the first coil 21 and the second coil 22 are adjacent (i.e., the +X direction in Figure 1).

[0054] <Preferred Embodiment of the Inductor of the First Embodiment> The following describes preferred embodiments of the inductor of the first embodiment. As a specific embodiment of the first coil 21 and the second coil 22 described above, when the direction along the winding axes O1 and O2 is defined as the +Z direction and the direction opposite to the Z direction is defined as the -Z direction, the specific embodiment of the inductor includes a first one-way lead conductor 31a extending along the +Z direction from one end of the first winding portion 51 of the first coil 21, a first other lead conductor 31b extending along the -Z direction from the other end of the first winding portion 51 of the first coil 21, a second one-way lead conductor 32a extending along the +Z direction from one end of the second winding portion 52 of the second coil 22, and a second other lead conductor 32b extending along the -Z direction from the other end of the second winding portion 52 of the second coil 22. Furthermore, the first one-way lead conductor 31a may be electrically connected to the first one-way conductor 41a provided on the first main surface 11 of the base body 10, the first other-way lead conductor 31b may be electrically connected to the first other-way conductor provided on the second main surface 12 of the base body 10, the second one-way lead conductor 32a may be electrically connected to the second one-way conductor 42a provided on the first main surface 11 of the base body 10, and the second other-way lead conductor 32b may be electrically connected to the second other-way conductor 42b provided on the second main surface 12 of the base body 10. Because lead conductors and conductors are provided in this manner, high-density mounting of inductors becomes possible.

[0055] Furthermore, as described above, the second coil 22 has the same structure as the first coil 21 when inverted vertically, and is therefore in a "symmetrical relationship" as defined herein. In this case, when the direction perpendicular to the +Z direction is defined as the ±X direction, and the directions perpendicular to both the +Z direction and the +X direction are defined as the ±Y direction, the first one-sided lead conductor 31a may be shifted in the ±Y direction relative to the first other lead conductor 31b, and the second one-sided lead conductor 32a may be shifted in the ±Y direction relative to the second other lead conductor 32b. Specifically, as shown in Figure 2B, the first one-sided lead conductor 31a is not shifted (or has little shift) in the X direction relative to the first other lead conductor 31b, but has a shift of ΔY in the Y direction. Similarly, the second one-sided lead conductor 32a is not shifted (or has little shift) in the X direction relative to the second other lead conductor 32b, but has a shift of ΔY in the Y direction. When the lead conductors are properly drawn out from the first winding section 51 and the second winding section 52 in this manner, it becomes possible to mount the inductor at an even higher density.

[0056] Regarding the preferred relationship between the lengths of the first one-sided lead conductor 31a, the first other lead conductor 31b, the second one-sided lead conductor 32a, and the second other lead conductor 32b, as shown in Figure 2A, the length D1 of the first one-sided lead conductor 31a in the +Z direction may be longer than the length D2 of the first other lead conductor 31b in the -Z direction, and the length D3 of the second one-sided lead conductor 32a in the +Z direction may be shorter than the length D4 of the second other lead conductor 32b in the -Z direction. With such a relationship between the lengths of the lead conductors, the first winding portion 51 of the first coil 21 and the second winding portion 52 of the second coil 22 can be suitably partially overlapped in a plan view, thereby reducing the magnetic coupling between the coils while further miniaturizing the shape in the +X direction.

[0057] Regarding a preferred relationship for the lengths of the further first one-way lead conductor 31a, the first other lead conductor 31b, the second one-way lead conductor 32a, and the second other lead conductor 32b, the length D1 of the first one-way lead conductor 31a in the +Z direction may correspond to the length D4 of the second other lead conductor 32b in the -Z direction, and the length D2 of the first other lead conductor 31b in the -Z direction may correspond to the length D3 of the second one-way lead conductor 32a in the +Z direction. The term "corresponding lengths" as used herein may include not only cases where the two lengths are identical, but also cases where there is an error of approximately ±10%.

[0058] Regarding the specific arrangement of the first one conductor 41a, the first other conductor 41b, the second one conductor 42a, and the second other conductor 42b, the first one conductor 41a may be offset in the ±Y and ±X directions relative to the second one conductor 42a, and the first other conductor 41b may be offset in the ±Y and ±X directions relative to the second other conductor 42b. Specifically, as shown in Figure 2B, the first one conductor 41a is offset by ΔY and ΔX relative to the second one conductor 42a, and the first other conductor 41b is offset by ΔY and ΔX relative to the second other conductor 42b. When the first one conductor 41a, the first other conductor 41b, the second one conductor 42a, and the second other conductor 42b are arranged in this manner, it becomes possible to mount the inductor of this embodiment at an even higher density.

[0059] <Modified Examples of the Inductor of the First Embodiment> Next, modified examples of the inductor 1A of the first embodiment will be described with reference to Figure 4. Figure 4 is a perspective view of an inductor according to a modified example of the first embodiment of this disclosure.

[0060] A modified version of the inductor 1A of the first embodiment is one in which multiple coil groups CG, each comprising a first coil 21 and a second coil 22, are arranged in a direction intersecting the winding axis (X direction). Figure 4 shows a configuration in which four coil groups CG are arranged. By arranging multiple coil groups CG in a direction intersecting the winding axis O1, O2 (X direction), multiple coil groups CG can be packaged together to form an electronic device.

[0061] Furthermore, in this modified inductor, in a plan view, the first one conductor 41a and the second one conductor 42a of the multiple coil group CG may be arranged in a staggered pattern relative to each other. Also, in a plan view, the first other conductor 41b and the second other conductor 42b of the multiple coil group CG may be arranged in a staggered pattern relative to each other. In this specification, "staggered pattern" means that one electrode aligned in the X direction and the other electrode aligned in the X direction are arranged alternately offset in the Y direction. When the first one conductor 41a and the second one conductor 42a of the multiple coil group CG are arranged in a staggered pattern relative to each other in this way, the first coil 21 and the second coil 22 can be arranged in a space-saving manner while preventing short circuits between the first one conductor 41a and the second one conductor 42a.

[0062] Furthermore, in the modified inductor, the first coil 21 and the second coil 22 of the multiple coil groups CG may be symmetrical with respect to each other, with the center of the ±X, ±Y, and ±Z directions inside the base body 10 being the point of symmetry SP (see Figure 4). In this specification, "the first coil 21 and the second coil 22 of the multiple coil groups CG are symmetrical with respect to each other" means that when the multiple coil groups CG are moved horizontally a predetermined distance in the +X direction, they will overlap with other multiple coil groups CG. Alternatively, it means that when rotated 180° around a symmetry axis parallel to the Z axis passing through the point of symmetry SP, each side constituting one coil group CG coincides with, is parallel to, or overlaps with each side constituting the other coil group. Specifically, in Figure 4, if the center of the ±X, ±Y, and ±Z directions is defined as the point of symmetry SP, then when multiple coil groups CG are moved horizontally along the +X axis to the point of symmetry SP, the coil groups may overlap. Alternatively, in Figure 4, when rotated 180° around the Z axis passing through the point of symmetry SP, the outer contours of the first coil 21 and the second coils of the multiple coil groups CG may overlap. Alternatively, in Figure 4, when rotated 180° around the Z axis passing through the point of symmetry SP, the tangent to the outer contour of the first coil 21 and the outer contour of the second coils of the multiple coil groups CG may be parallel. Because the inductor in this modified example has the symmetrical arrangement described above, it can be properly implemented even if the inductor is reversed in the left-right direction.

[0063] <Inductor of the Second Embodiment> Next, the inductor of the second embodiment will be described with reference to Figures 5 and 6. Figure 5 is a perspective view of the inductor according to the second embodiment of this disclosure, and Figure 6 is an exploded perspective view of the inductor according to the second embodiment of this disclosure. In describing the inductor of the second embodiment, points that are common with the description in the section on <Inductor of the First Embodiment> above will be omitted as appropriate. In other words, the following description will focus on the points that differ from the description in the section on [Inductor of the First Embodiment] above.

[0064] In the second embodiment, the inductor 1B has a cross-sectional shape in which the cross-sectional shape of the first one-sided lead conductor 31a and the second one-sided lead conductor 32a differs from the cross-sectional shape of the first other lead conductor 31b and the second other lead conductor 32b of the first other lead conductor 32b of the second coil 22. More specifically, as shown in Figure 6, in the stacked group G2, the cross-sectional shape of the second one-sided lead conductor 32a in the second coil 22 is rectangular when cut in the XY plane, while the cross-sectional shape of the second other lead conductor 32b in the second coil 22 is circular when cut in the XY plane. By making the shapes of the first one-sided lead conductor 31a and the second one-sided lead conductor 32a different in this way, the vertical direction of the inductor 1B can be determined by photographing the internal structure of the inductor 1B with X-rays, and the inductor can be properly mounted with the vertical direction determined. In the illustrated example, the cross-sectional shape of the lead conductor on the second coil 22 side is described as being different, but the cross-sectional shape of the lead conductor on the first coil 21 side may also be different, or the vertical direction of the inductor can be specified by differentiating the cross-sectional shapes of both the first coil 21 and the second coil 22.

[0065] Furthermore, in the second embodiment, the inductor 1B may have different cross-sectional shapes for one of the lead conductors of the first coil 21 and one of the lead conductors of the second coil 22. In Figure 6, the second lead conductor 32a in the second coil 22 (with a square cross-sectional shape) and the first lead conductor 31a in the first coil 21 (with a circular cross-sectional shape) have different shapes. By making the cross-sectional shapes of one lead conductor different for the first coil 21 and the second coil 22 in this way, the left-right direction of the inductor 1B can be determined by photographing its internal structure with X-rays, and the inductor can be properly mounted with the left-right direction determined.

[0066] <Modified Inductor of Second Embodiment> Furthermore, as a modified version of the inductor of the second embodiment, as shown in Figure 7, a plurality of coil groups CG, each comprising a first coil 21 and a second coil 22, may be arranged in a direction intersecting the winding axis (X direction). By arranging a plurality of coil groups CG in a direction intersecting the winding axis (X direction), multiple coil groups CG can be made into an electronic device in a single package.

[0067] <Method for Manufacturing an Inductor> Next, the method for manufacturing an inductor according to the present disclosure will be described. The method for manufacturing an inductor according to the present disclosure comprises a body formation step for forming a base body, a grinding step, and an electrode formation step. Furthermore, a degraining step may be included after the grinding step. The details of each step will be described below.

[0068] -Bottom Formation Process- Prepare the magnetic material (magnetic paste) that constitutes the magnetic layer ML of the laminated groups G1 to G7 as explained in Figure 3, and the conductive paste that constitutes the coil conductor CD.

[0069] As an example of a material for magnetic paste, a metallic magnetic powder containing Fe and Si with a D50 (cumulative 50% particle size by volume) of 2 μm to 20 μm is prepared. Then, a magnetic paste is produced by kneading the metallic magnetic powder with a binder such as cellulose or polyvinyl butyral (PVB) and a solvent such as a mixture of terpineol and butyl diglycol acetate (BCA).

[0070] As a conductive paste, for example, a paste containing Ag as a conductive material is prepared. However, the conductive material is not limited to Ag; a paste made from a conductive material such as Cu, Au, or an alloy thereof may also be used.

[0071] Using the magnetic paste and conductive paste described above, the laminate groups G1 to G7 shown in Figure 3 are prepared and laminated by screen printing or the like.

[0072] After lamination of lamination groups G1 to G7, lamination groups G1 to G7 are pressurized. This pressurization may be performed at a pressure of 300 MPa or higher. Pressurizing lamination groups G1 to G7 can improve the packing density of metal magnetic powder MP within the lamination of lamination groups G1 to G7.

[0073] A suitable manufacturing process for an inductor may include a degreasing step. The degreasing step is a process of removing the binder contained in the magnetic paste and conductive paste. For example, degreasing is performed in an air atmosphere at a temperature of approximately 300°C to 500°C. This removes the binder contained in the magnetic paste and conductive paste.

[0074] A heat treatment is performed after the degreasing process. Air, nitrogen, or nitrogen and hydrogen are injected into the furnace of the heat treatment apparatus. The heat treatment temperature is such that the coil conductor sintersects, for example, it may be between 400°C and 1000°C. Furthermore, to achieve both a reduction in coercivity and suppression of heat diffusion of the coil conductor material components into the base material, it is desirable to set the temperature between 600°C and 800°C. Through this heat treatment, adjacent metal magnetic powders MP are bonded together by an insulating oxide film OL.

[0075] Furthermore, in order to further improve the strength of the base material after heat treatment, an insulating resin material may be impregnated into the base material 10 after heat treatment. The resin material used for impregnation is epoxy resin, but one or more resins selected from the group consisting of phenolic resin, polyester resin, polyimide resin, polyolefin resin, silicone resin, acrylic resin, polyvinyl butyral resin, cellulose resin, and alkyd resin may also be used.

[0076] -Grinding Process- The grinding process is a process to expose the lead conductors 31a, 31b, 32a, and 32b from the first main surface 11 and the second main surface 12 of the base body 10. Specifically, by grinding the first main surface 11 and the second main surface 12 of the base body 10, the first one-sided lead conductor 31a, the first other-sided lead conductor 31b, the second one-sided lead conductor 32a, and the second other-sided lead conductor 32b are exposed from the base body 10, and electrical connectivity with the first one-sided conductor 41a, the first other-sided conductor 41b, the second one-sided conductor 42a, and the second other-sided conductor 42b, which will be described later. In other words, the first main surface 11 and the second main surface 12 of the base body 10 are exposed by removing the resin material impregnated into the base body 10 as described above, thereby exposing the first one-way lead conductor 31a, the first other-way lead conductor 31b, the second one-way lead conductor 32a, and the second other-way lead conductor 32b. Alternatively, instead of the mechanical grinding described above, the surface may be ground (or cleaned) by irradiating it with a laser. Furthermore, the grinding process may consist of grinding at least one of the first main surface 11 and the second main surface 12 of the base body 10.

[0077] Furthermore, the grinding process may also be performed on the first end face 13, second end face 14, first side surface 15 and / or second side surface of the base body 10 in order to shape the base body 10. Also, the grinding process is not limited to a grinding method, and any method can be used as long as the first one-way lead conductor 31a, the first other-way lead conductor 31b, the second one-way lead conductor 32a, and the second other-way lead conductor 32b can be exposed from the base body 10. For example, the first one-way lead conductor 31a, the first other-way lead conductor 31b, the second one-way lead conductor 32a, and the second other-way lead conductor 32b can be exposed from the base body 10 by chemical etching.

[0078] - Degraining Process - The degraining process is a process of degraining the metallic magnetic particles DP from the first main surface 11 and the second main surface 12 of the base material 10. Specifically, the metallic magnetic particles 10a are removed from the first main surface 11 and the second main surface 12 of the base material 10 by immersing the base material 10 containing the metallic magnetic particles DP in an acidic solution, as shown in Figure 2C. Sulfuric acid is an example of an acidic solution used to remove the metallic magnetic particles 10a.

[0079] After the degraining process, an insulating film IL (see Figure 2C) may be formed on the first main surface 11 and the second main surface 12 of the substrate 10, except for the positions where conductors connected to at least the first one-way drawn conductor 31a, the first other-way drawn conductor 31b, the second one-way drawn conductor 32a, and the second other-way drawn conductor 32b are formed. Specifically, the insulating film IL may be, for example, a photosensitive resist resin containing silica as a filler. The resist resin is applied to the entire surface of the first main surface 11 and the second main surface 12 of the substrate 10 by screen printing or the like. The photosensitive resist resin applied to the entire surface of the first main surface 11 and the second main surface 12 is then subjected to pattern exposure along the shape of the first one-way conductor 41a and the second one-way conductor 42a, or the first other-way conductor 41b and the second other-way conductor 42b, as described later, and then immersed in a developer solution. Then, the insulating film IL is removed from the locations where the first one-sided conductor 41a, the first other-sided conductor 41b, the second one-sided conductor 42a, and the second other-sided conductor 42b are formed. As a result, the insulating film IL is provided in all locations except where conductors connected to the first one-sided lead conductor 31a, the first other-sided lead conductor 31b, the second one-sided lead conductor 32a, and the second other-sided lead conductor 32b are formed on the base body 10, and thus the insulating properties may be enhanced by the insulating film IL. In addition, although the above-described method for forming the insulating film IL uses a photosensitive resist resin, as an insulating layer formation method other than screen printing, a resist film may be attached to the first main surface 11 and the second main surface 12 of the base body 10.

[0080] - Electrode Formation Process - The electrode formation process is a process of forming the first one-sided conductor 41a, the first other-sided conductor 41b, the second one-sided conductor 42a, and the second other-sided conductor 42b at the positions where the first one-sided drawn conductor 31a, the first other-sided drawn conductor 31b, the second one-sided drawn conductor 32a, and the second other-sided conductor 32b are exposed in the base body 10. Specifically, a Pd catalyst is applied to the areas on the first main surface 11 and the second main surface 12 of the base body 10 from which the insulating coating IL has been removed, and the first one-sided conductor 41a, the first other-sided conductor 41b, the second one-sided conductor 42a, and the second other-sided conductor 42b are formed by electroless plating. Examples of plating materials include Cu plating, but in addition to Cu plating, Ni-Sn, Ni-Au, Ni-Cu, Cu-Ni-Au, etc. may be used.

[0081] After the electrode formation process, the element can be cut into individual pieces to manufacture the inductor of this embodiment.

[0082] As described above, the inductor manufacturing method described in this embodiment allows for the appropriate manufacture of the inductor 1A of the first embodiment or the inductor 1B of the second embodiment. In plan view, the inductor 1A of the first embodiment or the inductor 1B of the second embodiment has a symmetrical relationship between the shape of the first winding portion 51 of the first coil 21 and the shape of the second winding portion 52 of the second coil 22, and in plan view, the first winding portion 51 of the first coil 21 and the second winding portion 52 of the second coil 22 partially overlap. Therefore, compared to conventional inductors in which the first and second coils are stacked and built into a base body, it is possible to reduce the magnetic coupling between the coils while enabling miniaturization of the shape and high-density mounting.

[0083] The embodiments disclosed herein are illustrative in all respects and do not constitute a limiting interpretation. Therefore, the technical scope of this disclosure is not construed solely by the embodiments described above, but is defined based on the claims. Furthermore, the technical scope of this disclosure includes all modifications within the meaning and scope of equivalence to the claims.

[0084] The inductor and method for manufacturing the inductor described herein can be suitably used as electronic components that enable miniaturization and high-density mounting while reducing magnetic coupling between coils.

[0085] 1A, 1B Inductor 10 Element 10a Metallic magnetic particles 11 First main surface 12 Second main surface 13 First end surface 14 Second end surface 15 First side surface 16 Second side surface 21 First coil 22 Second coil 31a First one-way lead conductor 31b First other lead conductor 32a Second one-way lead conductor 32b Second other lead conductor 41a First one-way conductor 41b First other conductor 42a Second one-way conductor 42b Second other conductor 51 First winding section 52 Second winding section C Recess CD Coil conductor CG Coil group DP Metallic magnetic particles G1-G7 Laminated group IL Insulating coating L1, L2 Virtual diagonal ML Magnetic layer MP Metallic powder O1, O2 Winding axis OL Insulating oxide film P1, P2 Curved vertex SP symmetric point

Claims

1. An inductor comprising: a body containing magnetic particles; a first coil and a second coil disposed within the body, wherein the first coil and the second coil are arranged adjacent to each other in a direction intersecting the winding axis; in a plan view from the top surface of the body, the shape of the winding portion of the first coil is symmetrical to the shape of the winding portion of the second coil; and in a plan view from the top surface of the body, the winding portion of the first coil and the winding portion of the second coil partially overlap.

2. In a plan view from the top surface of the main body, the winding portion of the first coil and the winding portion of the second coil are curved, as described in claim 1.

3. When the direction along the winding axis is defined as the +Z direction and the direction opposite to the +Z direction is defined as the -Z direction, the coil comprises: a first one-way lead conductor extending from one end of the winding portion of the first coil along the +Z direction; a first other-way lead conductor extending from the other end of the winding portion of the first coil along the -Z direction; a second one-way lead conductor extending from one end of the winding portion of the second coil along the +Z direction; and a second other-way lead conductor extending from the other end of the winding portion of the second coil along the -Z direction, wherein the first one-way lead conductor is electrically connected to a first one-way conductor provided on one main surface of the element; the first other-way lead conductor is electrically connected to a first other-way conductor provided on the other main surface of the element; and the second one-way lead conductor is electrically connected to a second one-way conductor provided on one main surface of the element. The inductor according to claim 1 or 2, wherein the second other lead conductor is electrically connected to the second other conductor provided on the other main surface of the element.

4. The inductor according to claim 3, wherein when the direction perpendicular to the +Z direction is defined as the ±X direction, and the directions perpendicular to both the +Z direction and the +X direction are defined as the ±Y direction, the first one-way lead conductor is offset in the ±Y direction relative to the first other lead conductor, and the second one-way lead conductor is offset in the ±Y direction relative to the second other lead conductor.

5. The inductor according to claim 3 or 4, wherein when the direction perpendicular to the +Z direction is defined as the ±X direction, and the directions perpendicular to the +Z direction and the +X direction are defined as the ±Y direction, the first one conductor is offset from the second one conductor in the ±Y direction and the ±X direction, and the first other conductor is offset from the second other conductor in the ±Y direction and the ±X direction.

6. The inductor according to any one of claims 3 to 5, wherein the length of the first one-way lead conductor in the +Z direction is longer than the length of the first other lead conductor in the -Z direction, and the length of the second one-way lead conductor in the +Z direction is shorter than the length of the second other lead conductor in the -Z direction.

7. The inductor according to any one of claims 3 to 6, wherein the length of the first one-way lead conductor in the +Z direction corresponds to the length of the second other lead conductor in the -Z direction, and the length of the first other lead conductor in the -Z direction corresponds to the length of the second one-way lead conductor in the +Z direction.

8. The inductor according to any one of claims 3 to 7, wherein the shape of the first one-way lead conductor, the first other lead conductor, the second one-way lead conductor, and the second other lead conductor is cylindrical or prismatic.

9. The inductor according to any one of claims 3 to 8, wherein at least one of the first coil and the second coil has a cross-sectional shape of one lead conductor and a cross-sectional shape of the other lead conductor that are different from each other.

10. The inductor according to any one of claims 3 to 8, wherein the cross-sectional shape of one of the lead conductors of the first coil and the cross-sectional shape of one of the lead conductors of the second coil are different from each other.

11. The inductor according to any one of claims 1 to 10, wherein a plurality of coil groups, each comprising the first coil and the second coil, are arranged in a direction intersecting the winding axis within the main body.

12. In a plan view from the top surface of the main body, the first one conductor provided by the plurality of coil groups and the second one conductor provided by the plurality of coil groups are arranged in a staggered pattern with respect to each other, and / or the first other conductor provided by the plurality of coil groups and the second other conductor provided by the plurality of coil groups are arranged in a staggered pattern with respect to each other, as described in claim 11, reference to claim 3.

13. The inductor according to claim 11 or 12, wherein, in the element, the first coil of the plurality of coil groups and the second coil of the plurality of coil groups are symmetrical with respect to the center of the element in the ±X, ±Y, and ±Z directions.

14. The inductor according to any one of claims 1 to 13, wherein at least one of the main surfaces of the substrate is provided with recesses where metallic magnetic particles have been removed.

15. The inductor according to any one of claims 1 to 14, wherein the base body is covered with an insulating film, and the surface roughness of the surface of the main surface of the base body in contact with the insulating film is greater than the surface roughness of the surfaces of other surfaces in contact with the insulating film.

16. A method for manufacturing an inductor according to any one of claims 1 to 14, comprising: a base body forming step of forming a base body by laminating a magnetic layer containing metallic magnetic particles, coil conductors corresponding to the winding portion of the first coil and the winding portion of the second coil, and lead conductors drawn out from the winding portion of the first coil and the winding portion of the second coil; a grinding step of grinding at least one of one of the main surface and the other main surface of the base body; and an electrode forming step of forming electrodes on the main surface and the other main surface of the base body that are electrically connected to the lead conductors.

17. The method for manufacturing an inductor according to claim 16, further comprising a degranulation step of degranulating the metal magnetic particles from the main surface of the base material after the grinding step.

18. The method for manufacturing an inductor according to claim 16 or 17, further comprising the step of forming an insulating coating material that covers one main surface and the other main surface of the base body, except for the position where a conductor connected to the lead conductor of the base body is formed, after the threshing step.

19. The method for manufacturing an inductor according to any one of claims 16 to 18, wherein the base body forming step includes a step of impregnating the base body with an insulating resin material, and the grinding step is a step of grinding the resin material impregnated on one main surface and the other main surface of the base body.

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