Coupling inductor

Abstract

Provided is a coupling inductor with which it is possible to adjust coupling coefficients of a plurality of coils provided in an element body. The present disclosure relates to a coupling inductor 1A-1D in which a first coil C1 and a second coil C2 that are arranged in an element body 10 and face each other in the stacking direction are magnetically coupled with each other, wherein: the element body 10 is provided with a magnetic layer ML containing first magnetic particles MP1, a plurality of coil conductors CD1, CD2 constituting the first coil C1 and the second coil C2, a first through conductor TH1 that electrically connects one end of the first coil C1 with a first external electrode 21 and extends in the stacking direction, a second through conductor TH2 that electrically connects the other end of the first coil C1 with a second external electrode 22 and extends in the stacking direction, a third through conductor TH3 that electrically connects one end of the second coil C2 with a third external electrode 23 and extends in the stacking direction, and a fourth through conductor TH4 that electrically connects the other end of the second coil C2 with a fourth external electrode 24 and extends in the stacking direction; and a coupling adjustment member 30 that adjusts the coupling coefficient between the coils is provided to at least part of the periphery of the first to fourth through conductors TH1-TH4.

Description

Coupled Inductor

[0001] The present disclosure relates to coupled inductors.

[0002] Patent Documents 1 and 2 disclose an inductor with two coils built into a single element body. Such an inductor is said to be capable of reducing the mounting area and enabling a highly efficient DC-DC converter.

[0003] US Patent Application Publication No. 2019-0279811 JP 2020-061415 A

[0004] In an inductor having two coils built into its element body, it is desired to be able to adjust the coupling coefficient between the two coils as appropriate depending on the application.

[0005] In the inductors described in Patent Documents 1 and 2, the coil coupling coefficient can be adjusted by adjusting the distance between the two coils. Here, the dimensions of the inductor are set to dimensions determined for each application. Therefore, weakening the magnetic coupling between the two coils requires increasing the distance between the two coils, which may result in the distance being larger than the determined dimension. Furthermore, strengthening the magnetic coupling between the two coils requires decreasing the distance between the two coils. If the distance between the two coils becomes too small, there is a risk that the voltage resistance performance cannot be ensured.

[0006] Therefore, a main object of the present disclosure is to provide a coupled inductor capable of adjusting the coupling coefficient of multiple coils provided within the element body.

[0007] The coupled inductor of the present disclosure is a coupled inductor in which a first coil and a second coil that are arranged within an element body and face each other in the stacking direction are magnetically coupled, wherein the element body comprises: a magnetic layer containing first magnetic particles; a plurality of coil conductors that constitute the first coil and the second coil; a first penetrating conductor that electrically connects one end of the first coil to a first external electrode and extends in the stacking direction; a second penetrating conductor that electrically connects the other end of the first coil to a second external electrode and extends in the stacking direction; a third penetrating conductor that electrically connects one end of the second coil to a third external electrode and extends in the stacking direction; and a fourth penetrating conductor that electrically connects the other end of the second coil to a fourth external electrode and extends in the stacking direction, and a coupling adjustment member that adjusts the coupling coefficient between the coils is provided around at least a portion of the first to fourth penetrating conductors.

[0008] According to the coupled inductor of the present disclosure, a coupling adjustment member that adjusts the coupling coefficient between coils is provided around at least a portion of the first through fourth through conductors, thereby making it possible to adjust the coupling coefficient of multiple coils provided within the element body.

[0009] FIG. 1 is a perspective view of a coupled inductor according to the present disclosure. FIG. 2 is a perspective view schematically illustrating an example of the internal structure of a coupled inductor according to the present disclosure. FIG. 3 is an exploded perspective view of a coupled inductor according to a first embodiment. FIG. 4A is a schematic cross-sectional view of the coupled inductor according to the first embodiment taken along line A-A in FIG. 3. FIG. 4B is a schematic cross-sectional view of the coupled inductor according to the first embodiment taken along line B-B in FIG. 3. FIG. 5A is an enlarged cross-sectional view of the dashed line region in FIG. 4A. FIG. 5B is an enlarged cross-sectional view of a modified example of the dashed line region in FIG. 4A. FIG. 6A is a schematic cross-sectional view of the coupled inductor according to a second embodiment taken along line A-A in FIG. 3. FIG. 6B is a schematic cross-sectional view of the coupled inductor according to the second embodiment taken along line B-B in FIG. 3. FIG. 7A is a schematic cross-sectional view of the coupled inductor according to a third embodiment taken along line A-A in FIG. 3. FIG. 7B is a schematic cross-sectional view of the coupled inductor according to the third embodiment taken along line B-B in FIG. 3. Fig. 8A is a schematic cross-sectional view of the coupled inductor according to the fourth embodiment taken along line A-A in Fig. 3. Fig. 8B is a schematic cross-sectional view of the coupled inductor according to the fourth embodiment taken along line B-B in Fig. 3. Fig. 9 is a graph showing the relationship between the current amplitude in the inductor and the coupling coefficient. Fig. 10 is a graph showing the relationship between the magnetic permeability around the feedthrough conductor and the coupling coefficient.

[0010] The coupled inductor of the present disclosure will be described below. Note that the present disclosure is not limited to the following configuration and may be modified as appropriate without departing from the spirit of the present disclosure. In addition, a combination of multiple individual preferred configurations described below also constitutes the present disclosure.

[0011] The coupled inductor of the present disclosure is used in, for example, a DC-DC converter, but the laminated coupled inductor of the present disclosure can also be used for purposes other than DC-DC converters.

[0012] In this specification, terms indicating the relationship between elements (e.g., "parallel," "orthogonal," etc.) and terms indicating the shape of elements do not only mean the strict literal form, but also mean a range of substantial equivalence, for example, a range including a difference of about a few percent. Note that in this specification, the direction in which the magnetic layers and conductor layers that make up the element body are stacked is referred to as the "stacking direction."

[0013] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, scale, etc. may differ from those of the actual product.

[0014] <First Embodiment of Coupled Inductor> First, a first embodiment of a coupled inductor according to the present disclosure will be described with reference to Figures 1 to 5. Note that the shape and arrangement of the coupled inductor and each component are not limited to the examples shown in the figures. A coupled inductor 1A according to the first embodiment includes an element body 10 and an external electrode 20 provided on the mounting surface of the element body 10. Each component will be described in detail below.

[0015] -Element body- The element body 10 is, for example, a hexahedron having six faces. As an example, it may be a rectangular parallelepiped or approximately rectangular parallelepiped shape. The vertices and ridges of the element body 10 may be rounded. A vertex is a portion where three faces of the element body 10 intersect, and a ridge is a portion where two faces of the element body 10 intersect.

[0016] 1, the long side direction, short side direction, and height direction of the coupled inductor 1A and the element body 10 are respectively indicated as L direction, W direction, and T direction. The long side direction L, the short side direction W, and the height direction T are perpendicular to each other.

[0017] 1 has a first main surface 11 and a second main surface 12 that face each other in the height direction T, a first end surface 13 and a second end surface 14 that face each other in the long side direction L, and a first side surface 15 and a second side surface 16 that face each other in the short side direction W. A first external electrode 21, a second external electrode 22, a third external electrode 23, and a fourth external electrode 24 are formed on the first main surface 11 of the element body 10, which corresponds to the mounting surface (bottom surface of the element body) of the coupled inductor 1A.

[0018] FIG. 3 is an exploded perspective view schematically illustrating an example of the internal structure of a coupled inductor 1A according to the present disclosure. As shown in FIG. 3, the element body 10 includes a first coil conductor CD1 constituting the first coil C1, a second coil conductor CD2 constituting the second coil C2, a magnetic layer ML, first through fourth through conductors TH1 through TH4, and a coupling adjustment member 30. In this embodiment, as shown in FIG. 2, the element body 10 is formed by stacking multilayer groups G1 through G9, with first through fourth external electrodes 21 through 24 formed below the multilayer group G9. Each of the multilayer groups G1 through G9 may be formed by stacking multiple layers of the same pattern. Note that the boundaries between the layers in the multilayer structure of the element body 10 may disappear.

[0019] (Stacking Group G1) The stacking group G1 includes a magnetic layer ML and may constitute the second main surface 12 of the element body 10 (see FIG. 1).

[0020] (Lamination Group G2) The lamination group G2 may include a second coil conductor CD2 and a magnetic layer ML arranged around the second coil conductor CD2.

[0021] The second coil conductor CD2 of the multilayer group G2 may be wound along the outer edge of the magnetic layer ML from a position corresponding to the fourth external electrode 24 to a position corresponding to the via conductor V of the multilayer group G3 in a plan view.

[0022] (Stacking group G3) The stacking group G3 may include a fourth through conductor TH4, a coupling adjustment member 30 surrounding at least a portion of the periphery of the fourth through conductor TH4, a via conductor V, and a magnetic layer ML arranged around the via conductor V and the coupling adjustment member 30.

[0023] The fourth through conductor TH4 may electrically connect one end of the second coil conductor CD2 of the multilayer group G2 to the fourth through conductor TH4 of the multilayer group G4. The via conductor V of the multilayer group G3 may electrically connect the other end of the second coil conductor CD2 of the multilayer group G2 to one end of the second coil conductor CD2 of the multilayer group G4. Details of the coupling adjustment member 30 will be described later.

[0024] (Stacking group G4) The stacking group G4 may include a second coil conductor CD2, a fourth through conductor TH4, a coupling adjustment member 30 that surrounds at least a portion of the periphery of the fourth through conductor TH4, and a magnetic layer ML that is arranged around the second coil conductor CD2 and the coupling adjustment member 30.

[0025] The second coil conductor CD2 of the multilayer group G4 may be wound along the outer edge of the magnetic layer ML from a position corresponding to the via conductor V of the multilayer group G3 to a position corresponding to the third external electrode 23 in a plan view. Furthermore, the second coil conductor CD2 may include an avoidance portion A that avoids the fourth through conductor TH4. More specifically, the avoidance portion A may be configured to curve the second coil conductor CD2 inward in a plan view, and may avoid the fourth through conductor TH4. By providing the avoidance portion A, it is possible to avoid contact between the fourth through conductor TH4 and the second coil conductor CD2.

[0026] The coupling adjustment member 30 is disposed between the fourth through conductor TH4 and the second coil conductor CD2, and ensures insulation between the fourth through conductor TH4 and the second coil conductor CD2. The coupling adjustment member 30 may be provided up to the vicinity of the outer edge of the magnetic layer ML (i.e., near the end face and side face of the element body) in a plan view. This is not limited to the illustrated example, and the coupling adjustment member 30 may be exposed from the end face and side face of the element body. This configuration allows the fourth through conductor TH4 to be appropriately surrounded by the coupling adjustment member 30.

[0027] (Stacking group G5) The stacking group G5 may include a third through conductor TH3, a coupling adjustment member 30 surrounding at least a portion of the periphery of the third through conductor TH3, a fourth through conductor TH4, a coupling adjustment member 30 surrounding at least a portion of the periphery of the fourth through conductor TH4, and a magnetic layer ML arranged around each coupling adjustment member 30.

[0028] The third through conductor TH3 may electrically connect the third through conductor TH3 of the stacking group G4 to the third through conductor TH3 of the stacking group G6, and the fourth through conductor TH4 may electrically connect the fourth through conductor TH4 of the stacking group G4 to the fourth through conductor TH4 of the stacking group G6.

[0029] (Stacking group G6) The stacking group G6 may include a first coil conductor CD1, a third through conductor TH3, a coupling adjustment member 30 surrounding at least a portion of the periphery of the third through conductor TH3, a fourth through conductor TH4, a coupling adjustment member 30 surrounding at least a portion of the periphery of the fourth through conductor TH4, and a magnetic layer ML arranged around the first coil conductor CD1 and each coupling adjustment member 30.

[0030] The first coil conductor CD1 of the multilayer group G6 may be wound along the outer edge of the magnetic layer ML from a position corresponding to the second external electrode 22 in plan view to a position corresponding to the via conductor V of the multilayer group G7. Furthermore, the first coil conductor CD1 may include avoidance portions A that avoid the third through conductor TH3 and the fourth through conductor TH4. More specifically, the avoidance portions A may be configured to curve the first coil conductor CD1 inward in plan view, and may avoid the third through conductor TH3 and the fourth through conductor TH4. By providing the avoidance portions A, it is possible to prevent contact between the third through conductor TH3 and the fourth through conductor TH4 and the first coil conductor CD1.

[0031] The coupling adjustment members 30 are respectively disposed between the third through conductor TH3 and the first coil conductor CD1, and between the fourth through conductor TH4 and the first coil conductor CD1, ensuring insulation between each through conductor and the first coil conductor CD1. The coupling adjustment members 30 may be provided up to the vicinity of the outer edge of the magnetic layer ML in plan view (i.e., near the end face and side face of the element body). This is not limited to the illustrated example, and the coupling adjustment members 30 may be exposed from the end face and side face of the element body. This configuration allows the periphery of each through conductor to be appropriately surrounded by the coupling adjustment members 30.

[0032] (Stacking group G7) The stacking group G7 may include a second through conductor TH2, a coupling adjustment member 30 surrounding at least a portion of the periphery of the second through conductor TH2, a third through conductor TH3, a coupling adjustment member 30 surrounding at least a portion of the periphery of the third through conductor TH3, a fourth through conductor TH4, a coupling adjustment member 30 surrounding at least a portion of the periphery of the fourth through conductor TH4, a via conductor V, and a magnetic layer ML arranged around the via conductor V and each coupling adjustment member 30.

[0033] The second through conductor TH2 may electrically connect the second through conductor TH2 of the multilayer group G6 to the second through conductor TH2 of the multilayer group G8, the third through conductor TH3 may electrically connect the third through conductor TH3 of the multilayer group G6 to the third through conductor TH3 of the multilayer group G8, and the fourth through conductor TH4 may electrically connect the fourth through conductor TH4 of the multilayer group G6 to the fourth through conductor TH4 of the multilayer group G8. The via conductor V of the multilayer group G7 may electrically connect the other end of the second coil conductor CD2 of the multilayer group G6 to one end of the second coil conductor CD2 of the multilayer group G8.

[0034] (Stacking group G8) The stacking group G8 may include a first coil conductor CD1, a second through conductor TH2, a coupling adjustment member 30 surrounding at least a portion of the periphery of the second through conductor TH2, a third through conductor TH3, a coupling adjustment member 30 surrounding at least a portion of the periphery of the third through conductor TH3, a fourth through conductor TH4, a coupling adjustment member 30 surrounding at least a portion of the periphery of the fourth through conductor TH4, and a magnetic layer ML arranged around the second coil conductor CD2 and each coupling adjustment member 30.

[0035] The first coil conductor CD1 of the multilayer group G8 may be wound along the outer edge of the magnetic layer ML from a position corresponding to the via conductor V of the multilayer group G7 to a position corresponding to the first external electrode 21 in a plan view. Furthermore, the first coil conductor CD1 may include avoidance portions A that avoid the second through conductor TH2, the third through conductor TH3, and the fourth through conductor TH4, respectively. More specifically, the avoidance portions A may be configured to curve the second coil conductor CD2 inward in a plan view, and may avoid the second through conductor TH2, the third through conductor TH3, and the fourth through conductor TH4. By providing the avoidance portions A, it is possible to prevent the second coil conductor CD2 from contacting the second through conductor TH2, the third through conductor TH3, and the fourth through conductor TH4.

[0036] The coupling adjustment members 30 are respectively arranged between the second through conductor TH2 and the second coil conductor CD2, between the third through conductor TH3 and the second coil conductor CD2, and between the fourth through conductor TH4 and the second coil conductor CD2, ensuring insulation between each through conductor and the second coil conductor CD2. The coupling adjustment members 30 may be provided up to the vicinity of the outer edge of the magnetic layer ML in plan view (i.e., near the end face and side face of the element body). This is not limited to the illustrated example, and the coupling adjustment members 30 may be exposed from the end face and side face of the element body. This configuration allows the periphery of each through conductor to be appropriately surrounded by the coupling adjustment members 30.

[0037] (Stacking group G9) The stacking group G9 may include a first through conductor TH1, a coupling adjustment member 30 surrounding the first through conductor TH1, a second through conductor TH2, a coupling adjustment member 30 surrounding the second through conductor TH2, a third through conductor TH3, a coupling adjustment member 30 surrounding the third through conductor TH3, a fourth through conductor TH4, a coupling adjustment member 30 surrounding the fourth through conductor TH4, a via conductor V, and a magnetic layer ML arranged around the via conductor V and each coupling adjustment member 30.

[0038] As described above, when the element body 10 has a layered structure including the multilayer groups G1 to G9, the design freedom of the coupled inductor 1A is increased. For example, when manufacturing a coupled inductor 1A including the first external electrode 21 to the fourth external electrode 24 on the bottom surface (first principal surface 11) of the element body 10, it becomes easier to extend the coil conductor to the bottom surface side using a through conductor. The layered structure including the above-described multilayer groups G1 to G9 may be stacked from the second principal surface 12 side or the first principal surface 11 side of the element body 10. For example, a layered group in which the multilayer groups G1 to G5 are stacked in this order may be stacked with a separate layered group in which the multilayer groups G6 to G9 are stacked in the reverse order. Furthermore, the material constituting the through conductors and / or via conductors may be repeatedly printed sequentially by, for example, screen printing or the like until the via conductors reach the desired thickness, or may be formed by an inkjet method or other known method.

[0039] As described above, the element body 10 includes at least the magnetic material part MB formed by stacking magnetic layers ML and containing first magnetic particles MP1 and resin (not shown), coils (first coil C1 and second coil C2) embedded in the magnetic material part MB, the first through fourth through conductors TH1 to TH4, and coupling adjustment members 30 provided around at least a portion of each through conductor (see FIGS. 4A to 5B). Each element constituting the element body 10 will be described in detail below.

[0040] -Magnetic Material Portion- The magnetic material portion MB formed by stacking the magnetic layers ML may include first magnetic particles MP1 made of a magnetic material (see FIGS. 5A and 5B). The first magnetic particles MP1 may contain Fe and / or Si. More specifically, they may be Fe particles or Fe alloy particles. Examples of Fe alloys include Fe-Si alloys, Fe-Cr alloys, Fe-Si-Cr alloys, Fe-Si-Al alloys, Fe-Si-B-P-Cu-C alloys, and Fe-Si-B-Nb-Cu alloys. The first magnetic particles MP1 may also contain impurities such as Cr, Mn, Cu, Ni, P, S, or Co that are not intended during manufacturing. The first magnetic particles MP1 may also be contained in a magnetic paste. Therefore, the first magnetic particles MP1 may contain elements (for example, Cr, Al, Li, Zn, Zr) that are more easily oxidized than the Fe added when the magnetic paste is prepared.

[0041] The surfaces of the first magnetic particles MP1 described above may be covered with a first insulating coating OL1 (see FIGS. 5A and 5B). Covering the surfaces of the first magnetic particles MP1 with the first insulating coating OL1 improves the insulation between the first magnetic particles MP1, improving the withstand voltage of the inductor and suppressing eddy currents that occur in magnetic particles with large particle sizes due to the first magnetic particles MP1 being electrically connected to each other. Methods for forming the first insulating coating OL1 on the surfaces of the first magnetic particles MP1 include the sol-gel method and the mechanochemical method. The material constituting the first insulating coating OL1 may be an oxide of P, Si, or the like, zinc phosphate, or manganese phosphate. The first insulating coating OL1 may also be an oxide film formed by oxidizing the surfaces of the first magnetic particles MP1 with oxygen in the atmosphere, or an oxide film of an element more easily oxidized than Fe. The thickness of the first insulating coating OL1 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 using a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and the thickness of the first insulating coating OL1 covering the surface of the first magnetic particle MP1 can be measured from the obtained SEM or TEM photograph.

[0042] The average particle size of the first magnetic particles MP1 in the magnetic material portion MB may be preferably 1.5 μm or more and 50 μm or less, more preferably 5 μm or more and 20 μm or less, and even more preferably 5 μm or more and 10 μm or less. The average particle size of the first magnetic particles MP1 in the magnetic material portion MB can be measured using the procedure described below. An inductor sample is cut to obtain a cross-section of the sample. Specifically, the sample is cut through the center of the element body 10, perpendicular to the mounting surface and end surface of the coil component, to obtain a cross-section of the sample. Multiple (e.g., five) regions (e.g., 130 μm x 100 μm) of the obtained cross-section are photographed using 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 circle-equivalent diameter of the magnetic particles. The average of the obtained circle-equivalent diameters is taken as the average particle size of the magnetic particles.

[0043] When forming the element body 10, a heat treatment may be performed. In this case, the first magnetic grains MP1 included in the element body 10 may have an oxide film (first insulating coating OL1) on their surfaces. This oxide film originates from the first magnetic grains MP1 and is formed by the heat treatment. In the element body 10, adjacent first magnetic grains MP1 are joined to each other via the oxide film to form the magnetic body part MB.

[0044] In order to further improve the strength of the element body 10, the element body 10 may be impregnated with a resin material after firing the element body 10. As an example of a resin that increases the strength of the element body, an epoxy resin and / or a phenol resin and / or a silicone resin may be used.

[0045] - Coil - The coil of this embodiment includes a first coil C1 and a second coil C2 that face each other in the stacking direction. The first coil C1 and the second coil C2 are magnetically coupled. In this specification, "magnetic coupling" refers to causing the magnetic flux generated in one coil to act on the other coil. In addition, magnetic coupling can be performed in several ways: a way in which the magnetic flux generated in one coil acts on the other coil, thereby strengthening the magnetic flux; a way in which the magnetic flux generated in one coil is affected by the other coil, thereby weakening the magnetic flux; and a way in which the coils are not coupled to each other.

[0046] Furthermore, the direction of the current flowing through the first coil C1 and the direction of the current flowing through the second coil C2 may be the same or opposite. When the direction of the magnetic flux generated by the current flowing through the first coil C1 and the direction of the magnetic flux generated by the current flowing through the second coil C2 are the same, the magnetic fluxes act to reinforce each other. On the other hand, when the direction of the magnetic flux generated by the current flowing through the first coil C1 and the direction of the magnetic flux generated by the second coil C2 are opposite, the magnetic fluxes act to weaken each other.

[0047] First Coil The first coil C1 includes multiple first coil conductors CD1 in the stacking direction (e.g., height direction T). Adjacent first coil conductors CD1 are connected to each other via via conductors V (see FIG. 3 ). The first coil C1 may have a desired number of turns by including first coil conductors CD1 formed in two different stacking groups in the stacking direction (see FIG. 3 ). In this embodiment, the first coil C1 may be configured using stacking groups G6 and G8. The number of turns may be set to, for example, two or more, by stacking the first coil conductors CD1 in the stacking direction.

[0048] The thickness of each of the first coil conductors CD1 is preferably the same as that of a second coil conductor CD2, which will be described later.

[0049] The first coil conductor CD1 may be made of a metal conductor such as Ag, Cu, and / or Pd, and may be formed by printing a conductive paste on the magnetic layer ML, for example.

[0050] Second Coil The second coil C2 includes multiple second coil conductors CD2 in the stacking direction (e.g., height direction T). Adjacent second coil conductors CD2 are connected to each other via via conductors V. The second coil C2 may have a desired number of turns by including second coil conductors CD2 formed in two different stacking groups in the stacking direction (see FIG. 3). In this embodiment, the second coil C2 may be formed by stacking groups G2 and G4. The number of turns may be set to, for example, two or more, by stacking the second coil conductors CD2 in the stacking direction.

[0051] The thickness of each of the second coil conductors CD2 is preferably the same as that of the first coil conductor CD1.

[0052] The second coil conductor CD2 may be made of a metal conductor such as Ag, Cu, and / or Pd, and may be formed by printing a conductive paste on the magnetic layer ML, for example.

[0053] -Through conductors- The through conductors (first through conductor TH1 to fourth through conductor TH4) electrically connect the external electrode 20 to one end or the other end of the coil (first coil C1 or second coil C2). The through conductors may be made of the same material as the first coil conductor CD1 and the second coil conductor CD2. The through conductors may be formed, for example, by printing a conductive paste on the magnetic layer ML described above.

[0054] In a preferred embodiment of the through conductors, the height of the through conductors in the stacking direction may be such that the fourth through conductor TH4 is the greatest, followed by the third through conductor TH3, the second through conductor TH2, and the first through conductor TH1 in that order. When the heights of the through conductors in the stacking direction are set in this manner, electrical wiring can be appropriately performed for the first external electrode 21 to the fourth external electrode 24 arranged on the mounting surface (second main surface 12) with the first coil C1 arranged above the second coil C2.

[0055] Coupling Adjustment Member The coupling adjustment member 30 is provided around at least a portion of the first through fourth through conductors TH1 to TH4, and adjusts the coupling between the first coil C1 and the second coil C2. Specifically, it adjusts the coupling coefficient between the coils.

[0056] The magnetic permeability of the coupling adjustment member 30 is different from the magnetic permeability of the magnetic layer ML of the element body 10. Therefore, by providing the coupling adjustment member 30 at least partially around the first through conductor TH1 to the fourth through conductor TH4, the inductance L mainly generated in each of the first through conductor TH1, the second through conductor TH2, the third through conductor TH3, and the fourth through conductor TH4 can be reduced. ＴＨ１ , L ＴＨ２ , L ＴＨ３ , L ＴＨ４ Conceptually, the inductance of each of the coupled inductors is L1 (the L value of the first coil C1) + L ＴＨ１ +L ＴＨ２ , L2 (L value of the second coil C2) + LＴＨ３ +L ＴＨ４ It can be considered that the inductance L1 of the first coil C1 and the inductance L2 of the second coil C2 are substantially coupled together. Therefore, the L value (L1) of the first coil C1 and the L value (L2) of the second coil C2, and the adjustment of the first coil C1 and the second coil C2 can be reduced, and the inductance L of the first through conductor TH1 to the fourth through conductor TH4 can be reduced. ＴＨ１ ~L ＴＨ４ It is possible to adjust the coupling coefficient by adjusting the inductance of the first through fourth through conductors TH1 to TH4. The adjustment range of the coupling coefficient becomes wider as the proportion of the inductance generated in the first through fourth through conductors TH1 to TH4 increases and the proportion of the inductance of the first coil C1 and the second coil C2 decreases.

[0057] In a preferred embodiment of the coupled inductor 1A of the present disclosure, the magnetic permeability of the coupling adjustment member 30 may be smaller than that of the magnetic layer ML. By making the magnetic permeability of the coupling adjustment member 30 smaller than that of the magnetic layer ML, the L values ​​of the first coil C1 and the second coil C2 can be reduced. This makes it possible to strengthen the coupling between the first coil C1 and the second coil C2.

[0058] One way to make the magnetic permeability of the coupling adjustment member 30 smaller than that of the magnetic layer ML is to configure the coupling adjustment member 30 by coating second magnetic particles MP2 made of a magnetic material with a second insulating coating OL2, using the same magnetic material for the second magnetic particles MP2 and the first magnetic particles MP1, and setting the average particle size of the second magnetic particles MP2 smaller than that of the first magnetic particles MP1 (see FIG. 5B ). Generally, magnetic materials with small particle sizes tend to have small magnetic permeabilities. Therefore, by making the average particle size of the second magnetic particles MP2 making up the coupling adjustment member 30 smaller than that of the first magnetic particles MP1, the magnetic permeability of the coupling adjustment member 30 can be made smaller than that of the magnetic layer ML.

[0059] As another means for making the magnetic permeability of the coupling adjustment member 30 smaller than that of the magnetic layer ML, the magnetic material of the coupling adjustment member 30 may be made of a material with a lower magnetic permeability than that of the magnetic layer ML. As an example, a non-magnetic material such as lumina, titania, zirconia, glass, or resin may be used, or an iron alloy containing more Cr or Si than the Fe particles or Fe alloy particles of the magnetic material of the coupling adjustment member 30 may be used. Iron alloys containing a large amount of Cr form a strong oxide film on the particle surfaces, making it easy to ensure insulation.

[0060] In a preferred embodiment of the coupled inductor of the present disclosure, the magnetic permeability of the coupling adjustment member 30 may be greater than that of the magnetic layer ML. By making the magnetic permeability of the coupling adjustment member 30 greater than that of the magnetic layer ML, the L value of the first coil C1 and the L value of the second coil C2 can be increased. This can weaken the coupling between the first coil C1 and the second coil C2.

[0061] One way to make the magnetic permeability of the coupling adjustment member 30 greater than that of the magnetic layer ML is to configure the coupling adjustment member 30 by coating second magnetic particles MP2 made of a magnetic material with a second insulating coating OL2, using the same magnetic material for the second magnetic particles MP2 and the first magnetic particles MP1, and setting the average particle size of the second magnetic particles MP2 greater than that of the first magnetic particles MP1 (see FIG. 5A ). By making the average particle size of the second magnetic particles MP2 constituting the coupling adjustment member 30 greater than that of the first magnetic particles MP1, the magnetic permeability of the coupling adjustment member 30 can be made greater than that of the magnetic layer ML.

[0062] As another means for making the magnetic permeability of the coupling adjustment member 30 greater than that of the magnetic layer ML, the magnetic material of the coupling adjustment member 30 may be made to have a higher magnetic permeability than that of the magnetic layer ML. As an example, the magnetic material of the coupling adjustment member 30 may be sendust, permalloy, permendur, ferrite powder, or the like, which has a higher magnetic permeability than Fe particles or Fe alloy particles.

[0063] In a preferred embodiment of the coupling adjustment member 30, the coupling adjustment member 30 may be provided around the avoidance portion A (see FIG. 3 ). With this configuration, the space between the coil conductor and the through conductor created by the avoidance portion A can be utilized to appropriately provide the coupling adjustment member 30 around the through conductor.

[0064] 4A and 4B, the coupled inductor 1A of the first embodiment may be provided with a coupling adjuster 30 over the entire area of ​​the first through fourth through conductors TH1 to TH4 in the stacking direction. With this configuration, since the coupling adjuster 30 is provided over the entire area of ​​each through conductor in the stacking direction, the coupling coefficient of the first coil C1 and the second coil C2 can be adjusted by increasing the L value of the first coil C1 and the second coil C2.

[0065] Next, a coupled inductor 1B according to a second embodiment will be described with reference to Figures 6A and 6B. The coupled inductor 1B according to the second embodiment differs from the coupled inductor 1A according to the first embodiment in the configuration of the coupling adjustment member 30. The following description will focus on the differences from the coupled inductor 1A according to the first embodiment.

[0066] 6A and 6B , in the coupled inductor 1B of the second embodiment, the coupling adjustment member 30 may be provided in a region R1 where the first through conductors TH1 to TH4 face the coil conductor in the stacking direction. In other words, the coupling adjustment member 30 is not provided in a region where the coil conductor and the through conductor do not face each other in the stacking direction. More specifically, the coupling adjustment member 30 is not provided in the first through conductor TH1. With this configuration, the coupling adjustment member 30 is disposed in the region R1 that relatively affects the L value of the coil conductor, and the L values ​​of the first coil C1 and the second coil C2 can be more effectively adjusted, thereby adjusting the coupling coefficient of the first coil C1 and the second coil C2.

[0067] Next, a coupled inductor 1C of a third embodiment will be described with reference to Figures 7A and 7B. The coupled inductor 1C of the third embodiment differs from the coupled inductor 1A of the first embodiment and the coupled inductor 1B of the second embodiment in the configuration of the coupling adjustment member 30. The following description will focus on the differences from the coupled inductor 1A of the first embodiment and the coupled inductor 1B of the second embodiment.

[0068] 7A and 7B , in the coupled inductor 1C of the third embodiment, the coupling adjuster 30 may be provided in a region R2 from the coil conductor in the stacking direction to the mounting surface of the element body 10. In other words, the coupling adjuster 30 is not provided in the region where the coil conductor and the through conductor face each other in the stacking direction. With this configuration, the coupling adjuster 30 is disposed in the region R2 that does not relatively affect the L value of the coil conductor, and the L values ​​of the first coil C1 and the second coil C2 can be finely adjusted, thereby precisely adjusting the coupling coefficient of the first coil C1 and the second coil C2.

[0069] Next, a coupled inductor 1D of a fourth embodiment will be described with reference to Figures 8A and 8B. The coupled inductor 1D of the fourth embodiment differs from the coupled inductor 1A of the first embodiment to the coupled inductor 1C of the third embodiment in the configuration of the coupling adjustment member 30. The following description will focus on the differences from the coupled inductor 1A of the first embodiment to the coupled inductor 1C of the third embodiment.

[0070] 8A and 8B , in the coupled inductor 1D of the fourth embodiment, the coupling adjustment member 30 may be provided in a region R3 between the first coil C1 and the second coil C2 in the stacking direction. In other words, the coupling adjustment member 30 may be provided only in the third through conductor TH3 and the fourth through conductor TH4, without being provided in the first through conductor TH1 and the second through conductor TH2. With this configuration, the coupling adjustment member 30 may be provided only in the third through conductor TH3 and the fourth through conductor TH4, allowing the coupling coefficient of the first coil C1 and the second coil C2 to be adjusted by a simple method.

[0071] Regarding the coupled inductor of the present disclosure, a simulation of the coupling coefficient using finite element analysis software "Femtet (registered trademark)" manufactured by Murata Software Co., Ltd. will be described in detail.

[0072] --Simulation 1: Relationship between coupling coefficient and ripple current-- Figure 9 shows a graph of the results of calculating the current amplitude inside the inductor when a square wave with a duty ratio of 25% is input to each of the first coil C1 and the second coil C2, and the coupling coefficient k between the first coil C1 and the second coil C2 is changed from -0.8 to 0.6.

[0073] According to the graph in Figure 9, the current amplitude takes a minimum value when the coupling coefficient is in the range of -0.2 to -0.6. From this result, it is possible to reduce the ripple current (fluctuations in current according to the switching frequency) by providing the coupling adjustment member 30 at least partially around the first through fourth through conductors TH1 to TH4 so that the coupling coefficient is -0.2 to -0.6. On the other hand, if the coupling coefficient is set so that the current amplitude exceeds 0.2 A, there is a risk that the current loss will increase and heat will be generated.

[0074] --Simulation 2: Relationship Between Coupling Coefficient and Permeability Around the Through Conductor-- FIG. 10 shows a graph of the results of a simulation using Femtet on the relationship between the coupling coefficient and the permeability around the through conductor.

[0075] According to the graph in Figure 10, as the magnetic permeability around the through conductor decreases, the absolute value of the coupling coefficient increases, and it can be seen that the coupling coefficient of the first coil and the second coil is appropriately adjusted.

[0076] It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present disclosure should not be interpreted solely by the above-described embodiments, but should be defined based on the claims. The technical scope of the present disclosure also includes all modifications within the scope and meaning equivalent to the claims.

[0077] The aspects of the coupled inductor disclosed herein are as follows: <1> A coupled inductor in which a first coil and a second coil are arranged within an element body and are magnetically coupled to each other in a stacking direction, wherein the element body comprises: a magnetic layer containing first magnetic particles; a plurality of coil conductors constituting the first coil and the second coil; a first penetrating conductor extending in the stacking direction and electrically connecting one end of the first coil to a first external electrode; a second penetrating conductor extending in the stacking direction and electrically connecting the other end of the first coil to a second external electrode; a third penetrating conductor extending in the stacking direction and electrically connecting one end of the second coil to a third external electrode; and a fourth penetrating conductor extending in the stacking direction and electrically connecting the other end of the second coil to a fourth external electrode, wherein a coupling adjustment member for adjusting a coupling coefficient between the coils is provided around at least a portion of the first to fourth penetrating conductors. <2> The coupled inductor according to <1>, wherein the magnetic permeability of the coupling adjuster is smaller than that of the magnetic layer. <3> The coupled inductor according to <2>, wherein the average particle size of the second magnetic particles contained in the coupling adjuster is smaller than that of the first magnetic particles. <4> The coupled inductor according to <1>, wherein the magnetic permeability of the coupling adjuster is larger than that of the magnetic layer. <5> The coupled inductor according to <4>, wherein the average particle size of the second magnetic particles contained in the coupling adjuster is larger than that of the first magnetic particles. <6> The coupled inductor according to any one of <1> to <5>, wherein the coil conductor is provided with an avoidance portion that avoids the second through fourth through conductors. <7> The coupled inductor according to <6>, wherein the coupling adjuster is provided around the avoidance portion. <8> The coupled inductor according to any one of <1> to <7>, wherein the coupling adjuster is provided over the entire area of ​​the first through fourth through conductors in the stacking direction. <9> A coupled inductor described in any one of <1> to <7>, wherein the coupling adjustment member is provided in an area of ​​the first through conductor to the fourth through conductor that faces the coil conductor in the stacking direction.<10> The coupled inductor according to any one of <1> to <7>, wherein the coupling adjustment member is provided in a region from the coil conductor to the mounting surface of the element body in the stacking direction. <11> The coupled inductor according to any one of <1> to <7>, wherein the coupling adjustment member is provided in a region between the first coil and the second coil in the stacking direction.

[0078] The coupled inductor of the present disclosure can be suitably used as an electronic device capable of adjusting the coupling coefficient of multiple coils provided within the element body.

[0079] 1A to 1D Coupled inductor 10 Element body 11 First main surface 12 Second main surface 13 First end surface 14 Second end surface 15 First side surface 16 Second side surface 20 External electrode 21 First external electrode 22 Second external electrode 23 Third external electrode 24 Fourth external electrode 30 Coupling adjustment member A Avoidance portion C1 First coil C2 Second coil CD1 First coil conductor CD2 Second coil conductor G1 to G9 Lamination group ML Magnetic layer MP1 First magnetic particle MP2 Second magnetic particle MB Magnetic material portion R1 to R3 Region TH1 First through conductor TH2 Second through conductor TH3 Third through conductor TH4 Fourth through conductor V Via conductor

Claims

1. A coupled inductor in which a first coil and a second coil are arranged within an element body and are magnetically coupled to each other in a stacking direction, wherein the element body comprises: a magnetic layer containing first magnetic particles; a plurality of coil conductors constituting the first coil and the second coil; a first penetrating conductor electrically connecting one end of the first coil to a first external electrode and extending in the stacking direction; a second penetrating conductor electrically connecting the other end of the first coil to a second external electrode and extending in the stacking direction; a third penetrating conductor electrically connecting one end of the second coil to a third external electrode and extending in the stacking direction; and a fourth penetrating conductor electrically connecting the other end of the second coil to a fourth external electrode and extending in the stacking direction, wherein a coupling adjustment member for adjusting the coupling coefficient between the coils is provided around at least a portion of the first to fourth penetrating conductors.

2. The coupled inductor according to claim 1, wherein the magnetic permeability of the coupling adjustment member is smaller than the magnetic permeability of the magnetic layer.

3. The coupled inductor according to claim 2, wherein the average particle size of the second magnetic particles contained in the coupling adjustment member is smaller than the average particle size of the first magnetic particles.

4. A coupled inductor according to any one of claims 1 to 3, wherein the magnetic permeability of the coupling adjustment member is greater than the magnetic permeability of the magnetic layer.

5. The coupled inductor according to claim 4, wherein the average particle size of the second magnetic particles contained in the coupling adjustment member is larger than the average particle size of the first magnetic particles.

6. A coupled inductor according to any one of claims 1 to 5, wherein the coil conductor is provided with avoidance portions that avoid the second through fourth through conductors.

7. The coupled inductor according to claim 6, wherein the coupling adjustment member is provided around the avoidance portion.

8. A coupled inductor according to any one of claims 1 to 7, wherein the coupling adjustment member is provided over the entire area of ​​the first through fourth through conductors in the stacking direction.

9. A coupled inductor according to any one of claims 1 to 8, wherein the coupling adjustment member is provided in an area of ​​the first through fourth through conductors that faces the coil conductor in the stacking direction.

10. A coupled inductor according to any one of claims 1 to 9, wherein the coupling adjustment member is provided in the region from the coil conductor to the mounting surface of the element body in the stacking direction.

11. A coupled inductor according to any one of claims 1 to 10, wherein the coupling adjustment member is provided in a region between the first coil and the second coil in the stacking direction.

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