Multilayer inductor
The multilayer inductor addresses coil inconsistencies by incorporating a main coil element perpendicular to the stacking direction and a sub-coil element with opposite magnetic flux, enhancing uniformity in electrical characteristics and reducing resistance and inductance variations.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-03-13
- Publication Date
- 2026-03-25
Smart Images
Figure 0007835183000001 
Figure 0007835183000002 
Figure 0007835183000003
Abstract
Description
Technical Field
[0001] The present disclosure relates to a stacked inductor.
Background Art
[0002] In recent years, due to the high functionality of devices, the DC-DC converters of voltage conversion circuits have been increasing in large current and high efficiency, and the rated current of the power inductors used in these devices has also been increasing. As a method for increasing the current and efficiency, a multi-phase method that adds the output currents from a plurality of inductors to increase the current is being adopted.
[0003] Patent Document 1, which shows an example of the above inductor, discloses a multilayer electronic component having a body including a magnetic layer containing magnetic particles, a first coil and a second coil built into the body, and first to fourth external electrodes provided on the bottom surface of the body and electrically connected to any one of the ends of each coil (see FIGS. 6A and 6B of Patent Document 1).
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] In a multi-phase DC-DC converter that drives a plurality of coils, it is desirable that the plurality of coils built into the inductor have small differences in electrical characteristics.
[0006] In the multilayer electronic component described in Patent Document 1, the number of turns of the upper first coil and the lower second coil are the same, but the length of the through-holes electrically connecting the first coil and the through-holes electrically connecting the second coil are different. As a result, the through-holes connected to the second coil are longer than those connected to the first coil, resulting in differences in DC resistance and inductance. Furthermore, the winding pattern based on the wiring structure or number of turns of the upper first coil may differ from the winding pattern of the lower second coil. Therefore, differences in inductance may occur. In short, in the multilayer electronic component described in Patent Document 1, there may be differences in electrical characteristics between the first coil and the second coil.
[0007] The primary object of this disclosure is to provide a multilayer inductor in which the difference in electrical characteristics between the first coil and the second coil is small. [Means for solving the problem]
[0008] The multilayer inductor disclosed herein is A base body with stacked magnetic layers, A first coil is provided inside the aforementioned body, and includes a plurality of first coil conductor layers in the stacking direction, and a second coil includes a plurality of second coil conductor layers in the stacking direction. The first coil comprises a first external electrode and a second external electrode electrically connected to the first coil, The first external electrode and the second external electrode are arranged on the bottom surface of the body. The second coil is provided at a position further from the bottom surface of the base body than the first coil in the stacking direction. The first coil comprises a main coil element consisting of a coil conductor whose stretching direction is perpendicular to the lamination direction, A sub-coil element is electrically connected in series with the main coil element and generates a magnetic flux in the opposite direction to the magnetic flux generated by the main coil element, It consists of. [Effects of the Invention]
[0009] According to this disclosure, it is possible to provide a multilayer inductor in which the difference in electrical characteristics between the first coil and the second coil is small. Specifically, the first coil of the multilayer inductor of this disclosure has a main coil element made of a coil conductor whose extension direction is perpendicular to the stacking direction, and a sub-coil element that is electrically connected in series with the main coil element and generates a magnetic flux in the opposite direction to the magnetic flux generated by the main coil element. Therefore, the number of turns of the main coil element can be increased due to the presence of the sub-coil element, and the difference in DC resistance and inductance values caused by the length of the through-hole and the winding pattern between the first coil and the second coil can be reduced. [Brief explanation of the drawing]
[0010] [Figure 1] Figure 1 is a schematic perspective view showing an example of a multilayer inductor according to the first embodiment. [Figure 2] Figure 2 is a schematic perspective view showing an example of the internal structure of a multilayer inductor according to the first embodiment. [Figure 3A] Figure 3A is a perspective view showing the first coil, first through-hole, and second through-hole extracted from the internal structure shown in Figure 2. [Figure 3B] Figure 3B is a perspective view showing the second coil, third through-hole, and fourth through-hole extracted from the internal structure shown in Figure 2. [Figure 4] Figure 4 is an exploded perspective view of the internal structure shown in Figure 2. [Figure 5] Figure 5 is a cross-sectional view taken in the direction of the arrow along the VV line in Figure 4. [Figure 6A] Figure 6A is an explanatory diagram illustrating the wiring direction of the main coil element in the first embodiment. [Figure 6B] Figure 6B is an explanatory diagram illustrating the wiring direction of the subcoil element in the first embodiment. [Figure 7] Figure 7 is an explanatory diagram illustrating the relationship between the magnetic flux of the main coil element and the magnetic flux of the subcoil element. [Figure 8]FIG. 8 is an exploded perspective view of the internal structure of the laminated inductor according to the second embodiment. [Figure 9A] FIG. 9A is an explanatory diagram for explaining the wiring direction of the main coil element according to the second embodiment. [Figure 9B] FIG. 9B is an explanatory diagram for explaining the wiring direction of the sub-coil element according to the second embodiment. [Figure 10] FIG. 10 is a perspective view schematically showing an example of the internal structure of the laminated inductor according to the third embodiment.
MODE FOR CARRYING OUT THE INVENTION
[0011] Hereinafter, the laminated inductor of the present disclosure will be described. Note that the present disclosure is not limited to the following configuration and may be appropriately changed without departing from the gist of the present disclosure. In addition, a combination of a plurality of the individual preferred configurations described below is also within the scope of the present disclosure.
[0012] The laminated inductor of the present disclosure is used, for example, in a DC-DC converter. The laminated inductor of the present disclosure is also applicable to uses other than DC-DC converters.
[0013] In this specification, terms indicating the relationship between elements (for example, "parallel", "orthogonal", etc.) and terms indicating the shape of elements do not only mean a strictly literal aspect, but also mean a substantially equivalent range, for example, a range including a difference of about several percent. In this specification, the direction in which the magnetic layer and the conductor layer constituting the element body are laminated is defined as the "lamination direction".
[0014] The drawings shown below are schematic diagrams, and their dimensions, scales of aspect ratios, etc. may be different from those of actual products.
[0015] <First Embodiment of the Laminated Inductor> First, a first embodiment of the multilayer inductor of this disclosure will be described with reference to Figures 1 to 7. Figure 1 is a schematic perspective view showing an example of a multilayer inductor of the first embodiment, Figure 2 is a schematic perspective view showing an example of the internal structure of the multilayer inductor of the first embodiment, Figure 3A is a perspective view showing the first coil, first through-hole, and second through-hole extracted from the internal structure shown in Figure 2, Figure 3B is a perspective view showing the second coil, third through-hole, and fourth through-hole extracted from the internal structure shown in Figure 2, Figure 4 is an exploded perspective view of the internal structure shown in Figure 2, Figure 5 is a cross-sectional view in the direction of the VV line in Figure 4, Figure 6A is an explanatory diagram illustrating the wiring direction of the main coil element of the first embodiment, Figure 6B is an explanatory diagram illustrating the wiring direction of the sub-coil element of the first embodiment, and Figure 7 is an explanatory diagram illustrating the relationship between the magnetic flux of the main coil element and the magnetic flux of the sub-coil element. Note that the shape and arrangement of the multilayer inductor and each component are not limited to the examples shown.
[0016] The multilayer inductor 1 shown in Figures 1 and 2 comprises a base body 10, a first coil 21, a second coil 22, a first external electrode 31, a second external electrode 32, a third external electrode 33, a fourth external electrode 34, a first through-hole 41, a second through-hole 42, a third through-hole 43, and a fourth through-hole 44. Additionally, an insulating layer 70 is provided on the bottom surface of the base body 10. Each component will be described in detail below.
[0017] -Base model- The base body 10 is, for example, a rectangular prism shape or a roughly rectangular prism shape having six faces. The corners and edges of the base body 10 may be rounded. The corners are the parts where three faces of the base body 10 intersect, and the edges are the parts where two faces of the base body 10 intersect.
[0018] Figures 1 and 2 show the length, width, and height directions of the multilayer inductor 1 and the base body 10 as the L, W, and T directions, respectively. The length direction L, the width direction W, and the height direction T are orthogonal to each other. The mounting surface of the multilayer inductor 1 is, for example, a surface parallel to the length direction L and the width direction W (LW surface).
[0019] The 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 T, a first end surface 13 and a second end surface 14 that are perpendicular to the height direction T and opposite to the length direction L, and a first side surface 15 and a second side surface 16 that are perpendicular to the length direction L and the height direction T and opposite to the width direction W. In the example shown in Figure 1, the first main surface 11 of the body 10 corresponds to the bottom surface of the body 10.
[0020] The base body 10 includes a magnetic layer S (see Figure 4). Preferably, the base body 10 has a laminated structure. Specifically, it is preferable that the base body 10 includes a plurality of magnetic layers S in the lamination direction (e.g., the height direction T). In this embodiment, as shown in Figure 4, it may be constructed by laminating magnetic layer groups G1 to G10, each containing at least one magnetic layer S. The boundaries between each layer of the laminated structure of the base body 10 may be obscured. Furthermore, each magnetic layer group may be constructed by laminating multiple identical patterns.
[0021] Magnetic layer group G1 has a magnetic layer S formed by stacking multiple identical patterns and constitutes the second main surface 12 of the base body 10. The number of stacked layers in magnetic layer group G2 may be one, but as an example, the number of stacked magnetic layers S may be two.
[0022] Magnetic layer group G2 has magnetic layers S formed by stacking multiple identical patterns. The number of stacked layers in magnetic layer group G2 may be one, and as an example, the number of stacked magnetic layers S may be four. Each of the magnetic layers S is provided with a second coil conductor layer 52 that constitutes a part of the second coil 22, and the multiple second coil conductor layers 52 of magnetic layer group G2 constitute one winding of the second coil 22 (90° × 4; that is, intended to be roughly enclosed in a plan view). More specifically, the second coil conductor layers 52 are arranged along the outer edge of the magnetic layer S. In addition, the ends of the second coil conductor layers 52 are spaced apart to form a winding structure.
[0023] Magnetic layer group G3 has a magnetic layer S formed by stacking multiple identical patterns. The number of layers in magnetic layer group G3 may be less than the number of layers in magnetic layer group G2 (for example, one layer). The magnetic layer S is provided with a conductor layer 80 (via conductor) for connecting the second coil conductor layer 52 of magnetic layer group G2 and the second coil conductor layer 52 of magnetic layer group G4, and a fourth through-hole 44 for electrically connecting the second coil conductor layer 52 and the fourth external electrode 34. The fourth through-hole 44 is located in the corner of the magnetic layer S in correspondence with the arrangement of the fourth external electrode, which will be described later. In this specification, "corner" refers to the position of a corner in a closed region (for example, the corner of a rectangular region). The conductor layer 80 is located near the fourth through-hole 44 from the viewpoint of increasing the inductance value by increasing the winding length of the second coil conductor layer 52.
[0024] Magnetic layer group G4 has a magnetic layer S formed by stacking multiple identical patterns. The number of stacked layers in magnetic layer group G4 may be one, but it is preferable to have a number of stacked layers similar to that of magnetic layer group G2 (for example, four layers). The magnetic layer S is provided with a second coil conductor layer 52 that constitutes part of the second coil, and multiple layers of the second coil conductor layer 52 constitute the other windings of the second coil 22 (90° × 3; that is, a C-shape or U-shape in plan view). The end of the second coil conductor layer 52 that is directly connected to the conductor layer 80 has a bypass portion 60 (see Figure 3A), which will be described later. In other words, the second coil conductor layer 52 of magnetic layer group G4 has a bypass portion 60 at one location. Furthermore, the end of the second coil conductor layer 52 that is directly connected to the third through-hole 43, which will be described later, is located in the corner of the magnetic layer S, corresponding to the arrangement of the third external electrode 33, which will be described later.
[0025] Magnetic layer group G5 has a magnetic layer S formed by stacking multiple identical patterns (for example, two layers). Note that the number of stacked magnetic layer groups G5 may be one layer. The magnetic layer S has a third through-hole 43 for electrically connecting the second coil conductor layer 52 and the third external electrode 33, and a fourth through-hole 44 for electrically connecting the second coil conductor layer 52 and the fourth external electrode 34, both provided at the corners.
[0026] Magnetic layer group G6 has magnetic layers S formed by stacking multiple identical patterns. The number of stacked layers in magnetic layer group G6 may be one, but it is preferable to have about the same number of stacked layers as magnetic layer group G4 (for example, four layers). Each of the magnetic layers S is provided with a main coil conductor layer 51a that constitutes part of the first coil 21, and the multiple main coil conductor layers 51a of magnetic layer group G6 constitute one winding (90° × 4) of the first coil 21. More specifically, the main coil conductor layers 51a are arranged along the outer edge of the magnetic layer S while avoiding the third through-hole 43 and the fourth through-hole 44 with avoidance portions 60 (see Figure 3B), and the ends of the main coil conductor layers 51a are spaced apart to form a winding structure. The avoidance portions 60 are configured to avoid the third through-hole 43 and the fourth through-hole 44, and the main coil conductor layer 51a of magnetic layer group G6 is provided with two avoidance portions 60.
[0027] Magnetic layer group G7 has a magnetic layer S formed by stacking multiple identical patterns. The number of stacked layers in magnetic layer group G7 may be one, but it is preferable that it be about the same as the number of stacked layers in magnetic layer group G3. The magnetic layer S is provided with a conductor layer 80 (via conductor) for connecting the main coil conductor layer 51a of magnetic layer group G6 and the main coil conductor layer 51a of magnetic layer group G8, a second through-hole 42 for electrically connecting the main coil conductor layer 51a and the second external electrode 32, a third through-hole 43 for electrical connection with the third external electrode 33, and a fourth through-hole 44 for electrical connection with the fourth external electrode 34. The second through-hole 42, the third through-hole 43, and the fourth through-hole 44 are each located at the corners of the magnetic layer S, and the conductor layer 80, which is directly connected to the main coil conductor layer 51a, is located adjacent to the second through-hole 42.
[0028] Magnetic layer group G8 has a magnetic layer S formed by stacking multiple identical patterns. The number of stacked layers in magnetic layer group G8 may be one, but it is preferable to have a number of stacked layers similar to that of magnetic layer group G6 (for example, four layers). The magnetic layer S is provided with a main coil conductor layer 51a that constitutes part of the first coil 21. The multiple main coil conductor layers 51a of magnetic layer group G8 constitute the other windings of the first coil 21 (larger than 90° × 3 and smaller than 90° × 4). More specifically, the main coil conductor layer 51a is arranged along the outer edge of the magnetic layer S while avoiding the second through-hole 42, third through-hole 43, and fourth through-hole 44 with avoidance portions 60 (see Figure 3B), and the ends of the main coil conductor layer 51a are spaced apart to form a winding structure. In other words, the main coil conductor layer 51a of magnetic layer group G8 is provided with three avoidance portions 60. In this disclosure, the main coil conductor layer 51a has an end that directly connects to the via conductor 80 and an end that directly connects to the first through-hole 41, arranged in close proximity, from the viewpoint of increasing the winding length of the first coil 21 and thereby increasing the inductance value. As a result, the main coil conductor layer 51a can be wound in the area where the sub-coil conductor layer 51b, described later, is provided.
[0029] Magnetic layer group G9 has a magnetic layer S formed by stacking multiple identical patterns. The number of stacked layers in magnetic layer group G9 may be one, but it is preferable to have more than magnetic layer group G7 (for example, four layers). The magnetic layer S has a second through-hole 42, a third through-hole 43, and a fourth through-hole 44 at its corners. On the other hand, the first through-hole 41 is not provided at the corners of the magnetic layer S. More specifically, the first through-hole 41 is located at a distance equal to the length of the sub-coil conductor layer 51b from the corners of the magnetic layer S.
[0030] Magnetic layer group G10 has a magnetic layer S formed by stacking multiple identical patterns. The number of stacked layers in magnetic layer group G10 may be one, but it is preferable to have a number of stacked layers similar to that of magnetic layer group G8 (for example, two layers). The magnetic layer S is provided with a subcoil conductor layer 51b that constitutes part of the first coil, a second through-hole 42, a third through-hole 43, and a fourth through-hole 44. Specifically, at the corners of the magnetic layer S, the second through-hole 42, the third through-hole 43, and the fourth through-hole 44 are provided at positions corresponding to the second external electrode 32, the third external electrode 33, and the fourth external electrode 34. In addition, a subcoil conductor layer 51b is provided at a position corresponding to the first external electrode 31. The subcoil conductor layer 51b extends parallel to the outer edge of the magnetic layer S toward the second through-hole 42.
[0031] As described above, if the base body 10 has a laminated structure comprising magnetic layer groups G1 to G10, the design freedom of the laminated inductor 1 is increased. For example, when manufacturing a laminated inductor 1 having a first external electrode 31, a second external electrode 32, a third external electrode 33, and a fourth external electrode 34 on the bottom surface (first main surface 11) of the base body 10, it becomes easier to pull out the first coil 21 and the second coil 22 to the bottom surface side.
[0032] The magnetic layer S contains magnetic particles made of a magnetic material. The magnetic particles may be particles of metallic magnetic materials such as Fe, Co, Ni, and alloys containing at least one of these (metallic magnetic particles) or ferrite particles. Preferably, the magnetic particles are Fe particles or Fe alloy particles. As for the Fe alloy, Fe-Si alloys, Fe-Si-Cr alloys, Fe-Si-Al alloys, Fe-Si-BP-Cu-C alloys, Fe-Si-B-Nb-Cu alloys, etc. are preferred.
[0033] The surface of the metallic magnetic particles made of the aforementioned metallic magnetic material is preferably covered with an insulating film. Covering the surface of the metallic magnetic particles with an insulating film increases the insulating properties between the metallic magnetic particles. Methods for forming the insulating film on the surface of the metallic magnetic particles include the sol-gel method and the mechanochemical method. The material constituting the insulating film is preferably an oxide such as P or Si. Alternatively, the insulating film may be an oxide film formed by the oxidation of the surface of the metallic magnetic particles. The thickness of the insulating film 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 a sample of a multilayer inductor can be photographed with a scanning electron microscope (SEM), and the thickness of the insulating film covering the surface of the metallic magnetic particles can be measured from the obtained SEM image.
[0034] The average particle size of the metallic magnetic particles in the magnetic layer S 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 in the magnetic layer can be measured by the procedure described below. A cross section obtained by cutting a sample of the multilayer inductor is photographed using an SEM in multiple locations (e.g., 5 locations) of a region (e.g., 130 μm × 100 μm). 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. The average value of the obtained equivalent circle diameters is taken as the average particle size of the metallic magnetic particles.
[0035] Furthermore, heat treatment is applied when forming the base body 10. In this case, the metallic magnetic particles contained in the base body 10 have an oxide film on their surface. This oxide film originates from the metallic magnetic particles and is formed by the heat treatment. In the base body 10, adjacent metallic magnetic particles are joined to each other via the oxide film.
[0036] The base body 10 may include a non-magnetic layer between the first coil 21 and the second coil 22. By providing a non-magnetic layer between the first coil 21 and the second coil 22, the insulation between the first coil 21 and the second coil 22 can be improved, and short circuits between them can be prevented.
[0037] The non-magnetic layer may contain glass ceramic material and non-magnetic ferrite material as non-magnetic materials. Preferably, the non-magnetic layer contains non-magnetic ferrite material. As the non-magnetic ferrite material, a non-magnetic ferrite material having a composition in which Fe is 40 mol% to 49.5 mol% of the entire non-magnetic layer when converted to Fe2O3, Cu is 6 mol% to 12 mol% of the entire non-magnetic layer when converted to CuO, and the remainder is ZnO can be used. The non-magnetic material may contain Mn3O4, Co3O4, SnO2, Bi2O3, SiO2, etc. as additives as needed, and may contain trace amounts of unavoidable impurities. Preferably, the non-magnetic layer contains Zn-Cu ferrite.
[0038] The thickness of the non-magnetic layer can be measured using the following procedure. The multilayer inductor sample is placed vertically, and the area around the sample is encased in resin. At this time, the LT surface is exposed. Polishing is completed with a polishing machine to a depth of approximately 1 / 2 of the sample's width (W) direction, exposing a cross-section parallel to the LT surface. To remove any sagging of the internal conductor caused by polishing, the polished surface is processed after polishing using ion milling (Hitachi High-Tech Corporation IM4000 ion milling device). The approximate center of the non-magnetic layer in the polished sample is photographed with an SEM, and the thickness of the approximate center of the non-magnetic layer is measured from the obtained SEM image and defined as the thickness of the non-magnetic layer.
[0039] The element 10 may include non-magnetic sections between the multiple main coil conductor layers 51a constituting the first coil 21, or between the multiple second coil conductor layers 52 constituting the second coil 22. In this case, the non-magnetic sections are provided at least at one location between adjacent coil conductor layers among the main coil conductor layers 51a and the second coil conductor layers 52. By providing non-magnetic sections between adjacent coil conductor layers, it is possible to prevent magnetic flux from leaking between the coil conductor layers and reducing the inductance value.
[0040] It is preferable that the non-magnetic layer and the non-magnetic portion have the same composition. For example, it is preferable that the non-magnetic layer and the non-magnetic portion are composed of Zn-Cu ferrite.
[0041] Inside the base body 10 are a first coil 21 and a second coil 22. Preferably, the first coil 21 and the second coil 22 are magnetically coupled. For example, the coupling coefficient between the first coil 21 and the second coil 22 is 0.1 or more and 0.8 or less. The base body 10 may contain only two coils, including the first coil 21 and the second coil 22, or it may contain three or more coils, including the first coil 21 and the second coil 22.
[0042] -Coil 1- The first coil 21 comprises a main coil element 21a consisting of a main coil conductor layer 51a whose stretching direction is perpendicular to the lamination direction, and a sub-coil element 21b consisting of a sub-coil conductor layer 51b that is electrically connected in series with the main coil element 21a.
[0043] (Main coil element) The main coil element 21a includes multiple main coil conductor layers 51a in the stacking direction (e.g., the height direction T). Adjacent main coil conductor layers 51a are connected via via conductors 80. The number of turns in the main coil element 21a may be greater than 1.75 by including main coil conductor layers 51a formed in two different magnetic layer groups in the stacking direction (see Figure 3). The number of turns is not limited to the two main coil conductor layers 51a shown in the example, and the number of turns may be increased by stacking magnetic layer groups containing main coil conductor layers 51a in the stacking direction.
[0044] The thickness and width of the main coil conductor layer 51a are preferably the same, but they may be different. Furthermore, the thickness and width of the main coil conductor layer 51a are preferably the same as the thickness and width of the second coil conductor layer 52 described later, but they may be different.
[0045] The main coil conductor layer 51a may be a metallic conductor such as Ag, Cu, and / or Pd, as an example of its material. The main coil conductor layer 51a may be formed, for example, by printing a conductive paste onto the magnetic layer S described above.
[0046] Figure 3A is a perspective view showing the main coil element 21a, sub-coil element 21b, first through-hole 41, and second through-hole 42 extracted from the internal structure shown in Figure 2.
[0047] The main coil element 21a may include avoidance portions 60 positioned inside the second through-hole 42, third through-hole 43, and fourth through-hole 44 in a plan view from the stacking direction (e.g., height direction T) to avoid the second through-hole 42, third through-hole 43, and fourth through-hole 44, and a straight portion 65 connected to the avoidance portions 60. By providing the avoidance portions 60, wiring can be appropriately drawn out from the main coil element 21a toward the external electrodes so that the second through-hole 42, third through-hole 43, and fourth through-hole 44 do not interfere with the main coil conductor layer 51a.
[0048] The avoidance portion 60 of the main coil element 21a only needs to be positioned inside the second through-hole 42 in a plan view from the stacking direction (e.g., height direction T) in order to avoid the second through-hole 42. In other words, the main coil element 21a only needs to include an avoidance portion 60 to avoid at least the second through-hole 42, and does not need to include an avoidance portion 60 to avoid at least one of the third through-hole 43 and the fourth through-hole 44. In the illustrated example, the winding portion on the bottom side of the main coil element 21a has three avoidance portions 60 to avoid the second through-hole 42, the third through-hole 43, and the fourth through-hole 44. In addition, the winding portion on the top side of the main coil element 21a has two avoidance portions 60 to avoid the third through-hole 43 and the fourth through-hole 44. In short, the avoidance portions 60 are provided in large numbers on the winding portion on the bottom side of the main coil element 21a.
[0049] The main coil element 21a has its end closer to the bottom directly connected to the first through-hole 41, and its end further from the bottom directly connected to the second through-hole 42.
[0050] (Subcoil element) The subcoil element 21b is electrically connected in series with the main coil element 21a. More specifically, one end of the subcoil element 21b may be directly connected to the first external electrode, and the other end of the subcoil element 21b may be electrically connected to the main coil element 21a via the first through-hole 41. With this configuration, the subcoil element 21b and the main coil element 21a can be properly electrically connected.
[0051] In a preferred configuration of the subcoil element 21b, the subcoil element 21b may overlap with a portion of the main coil element 21a when viewed from the stacking direction. Specifically, as shown in Figures 6A and 6B, when the first coil 21 is viewed planar from the stacking direction, it may have an overlapping region A where the main coil element 21a and the subcoil element 21b overlap. By providing the subcoil element 21b, the main coil element 21a can be extended from the corner by the length of the subcoil element 21b, rather than being stopped at the corner of the base body 10 when viewed from the stacking direction.
[0052] A more preferable configuration of the subcoil element 21b is one in which the subcoil element 21b is wound coaxially with the main coil element, and an insulating layer 70, described later, is provided on a portion of the bottom surface of the subcoil element 21b. This allows the laminated inductor 1 to be electrically connected by the first external electrode 31, which is directly connected to the subcoil element 21b, without the subcoil element 21b directly contacting the mounting substrate when the laminated inductor 1 is mounted on the mounting substrate.
[0053] -Coil 2- The second coil 22 is positioned further away from the bottom surface (first main surface 11) of the base body 10 than the first coil 21.
[0054] The second coil 22 includes a plurality of second coil conductor layers 52 in the stacking direction (e.g., the height direction T). Adjacent second coil conductor layers 52 are connected via conductors. The second coil 22 may have 1.75 turns by including second coil conductor layers 52 formed in two different magnetic layer groups in the stacking direction (see Figure 3B). The number of turns is not limited to the two second coil conductor layers 52 shown in the example, and may be increased by stacking magnetic layer groups including the main coil conductor layer 51a in the stacking direction. The number of stacked second coil conductor layers 52 may be the same as or different from the number of stacked main coil conductor layers 51a.
[0055] The thickness and width of the second coil conductor layer 52 are preferably the same, but they may be different. Furthermore, the thickness and width of the second coil conductor layer 52 are preferably the same as the thickness and width of the main coil conductor layer 51a, but they may be different.
[0056] The second coil conductor layer 52 may be made of a metal conductor such as Ag, Cu, and / or Pd, as an example of its material. Furthermore, the material of the second coil conductor layer 52 may be the same as that of the main coil conductor layer 51a, or a different material may be used. The second coil conductor layer 52 may be formed, for example, by printing a conductive paste onto the magnetic layer S described above.
[0057] Figure 3B is a perspective view showing the second coil 22, the third through-hole 43, and the fourth through-hole 44 extracted from the internal structure shown in Figure 2.
[0058] As shown in Figure 3B, the second coil conductor layer 52 may include avoidance portions 60 positioned inside each of the fourth through-holes 44 in a plan view from the stacking direction (e.g., height direction T) to avoid the fourth through-holes 44, and a straight portion 65 connected to the avoidance portions 60. By providing the avoidance portions 60, wiring can be appropriately drawn out from the second coil 22 toward the external electrode without interfering with the fourth through-holes 44. In the illustrated example, one avoidance portion 60 is provided in the winding portion on the bottom side of the second coil 22 to avoid the fourth through-hole 44. Also, no avoidance portion 60 is provided in the winding portion on the top side of the second coil 22. In other words, the number of avoidance portions 60 provided in the second coil 22 is less than the number of avoidance portions 60 provided in the first coil 21.
[0059] -Regarding the electrical characteristics of the first and second coils- As described above, the number of avoidance sections 60 provided on the second coil 22 is less than the number of avoidance sections 60 provided on the main coil element 21a. Therefore, if the main coil element 21a of the first coil 21 is secured at the corner of the base body 10 in a plan view from the stacking direction, the inner circumference area of the winding section of the first coil 21 will be smaller than the inner circumference area of the winding section of the second coil 22 due to the number of avoidance sections 60. Also, the distance from the bottom surface of the first coil will be shorter than the distance from the bottom surface of the second coil 22. That is, the heights of the first through-hole 41 and the second through-hole 42 of the first coil 21 are lower than the heights of the third through-hole 43 and the fourth through-hole 44 of the second coil 22. As a result, the inductance value of the first coil 21 will be smaller than the inductance value of the second coil 22, and the DC resistance value of the first coil 21 will be smaller than the DC resistance value of the second coil 22.
[0060] This disclosure provides a "sub-coil element 21b" to reduce the difference in inductance value and DC resistance value between the first coil 21 and the second coil 22 described above. In other words, the main coil element 21a of the first coil 21 is not terminated at the corner of the base body 10 in a plan view from the stacking direction, but extends from the corner by the length of the sub-coil element 21b. As a result, the winding length of the main coil of the first coil 21 can be increased, and the number of turns can be increased.
[0061] Here, the electrical characteristics of the subcoil element 21b and the main coil element 21a in this disclosure will be explained with reference to Figures 6A, B and 7.
[0062] As shown in Figure 6A, when current flows counterclockwise through the main coil element 21a, a magnetic flux is generated inside the main coil element 21a in the direction from the bottom to the top, as shown in Figure 7. On the other hand, as shown in Figure 6B, when current flows from the main coil element 21a to the sub-coil element 21b through the first through-hole 41, in the overlapping region A between the main coil element 21a and the sub-coil element 21b, the direction of the current in the main coil element 21a is opposite to the direction of the current in the sub-coil element 21b. As a result, a magnetic flux is generated around the sub-coil element 21b, and the direction of the generated magnetic flux is opposite to the direction of the magnetic flux generated from the main coil element 21a inside the sub-coil element 21b (towards the center of the element 10), so the magnetic fluxes cancel each other out and the inductance value cannot be increased (see Figure 7). However, the main coil element 21a is located inside the element 10, while the sub-coil element 21b is located on the surface of the element 10, away from the main coil element 21a. As a result, the inductance value generated in the sub-coil element 21b becomes smaller than the inductance value generated in the main coil element 21a, and consequently the inductance value of the first coil 21 increases. In addition, the DC resistance value of the first coil 21 can be made larger than that of the second coil 22 by the amount of overlap region A of the main coil element 21a and the sub-coil element 21b.
[0063] Therefore, it is preferable that the main coil element 21a and the sub-coil element 21b are separated. Specifically, it is preferable to separate the main coil element 21a and the sub-coil element 21b by a first through-hole 41 that electrically connects the main coil element 21a and the sub-coil element 21b. More specifically, the distance D1 between the sub-coil element 21b and the main coil element 21a in the stacking direction may be longer than the interlayer distance D2 between the main coil conductor layers 51a in the stacking direction (see Figure 5). With such a configuration, the mutual influence between the magnetic flux of the main coil element 21a and the magnetic flux of the sub-coil element 21b can be further reduced.
[0064] Furthermore, in order to further separate the subcoil element 21b and the main coil element 21a, the subcoil element 21b may be provided so as to be exposed on the bottom surface of the base body 10. With such a configuration, the influence of each other's magnetic flux can be further reduced.
[0065] As described herein, the winding length of the main coil of the first coil 21 can be increased, thereby increasing the number of turns, and thus reducing the difference between the inductance value of the first coil 21 and the inductance value of the second coil 22. Furthermore, by providing a sub-coil element 21b to the first coil 21, the winding length of the first coil 21 can be increased, thereby reducing the difference in DC resistance values.
[0066] More specifically, the multilayer inductor 1 of this disclosure includes a subcoil element, so that the inductance value between the first coil 21 and the second coil 22 can be within a range of ±10%. Here, the inductance value is measured between the external electrodes using an impedance analyzer.
[0067] In a preferred embodiment of the multilayer inductor of this disclosure, the number of turns of the main coil element 21a of the first coil 21 may be greater than the number of turns of the second coil 22. In the multilayer inductor shown in Figure 2, the number of turns of the main coil element 21a of the first coil 21 is 1.80, and the number of turns of the second coil 22 is 1.75. In other words, since the number of turns of the main coil element of the first coil 21 is greater than that of the second coil 22, and there is also a sub-coil element 21b, the first coil 21 uses more coil conductor for winding. With this configuration, even if the DC resistance of the second coil 22 increases because the second coil 22 is positioned further from the bottom surface of the base body 10 than the first coil 21 in the stacking direction, the difference in DC resistance between the first coil 21 and the second coil 22 can be reduced because the first coil 21 uses more coil conductor. Here, the DC resistance is measured between the external electrodes using a digital multimeter.
[0068] Furthermore, since the multilayer inductor 1 of this disclosure includes a subcoil element, the DC resistance value can be within ±20% of the range between the first coil 21 and the second coil 22.
[0069] -External electrode- The external electrodes include a first external electrode 31, a second external electrode 32, a third external electrode 33, and a fourth external electrode 34. The first external electrode 31 and the second external electrode 32 are provided on the bottom surface (first main surface 11) of the base body 10 and are electrically connected to the first coil 21. The third external electrode 33 and the fourth external electrode 34 are provided on the bottom surface (first main surface 11) of the base body 10 and are electrically connected to the second coil 22. In the multilayer inductor 1, the bottom surface (first main surface 11) of the base body 10 can be used as the mounting surface. That is, mounting on the bottom surface of the multilayer inductor 1 becomes possible.
[0070] The first external electrode 31 acts as an output electrode for the first coil 21. The first external electrode 31 may be provided only on the first main surface 11 of the base body 10, or it may be provided spanning the first main surface 11 and at least one of the first end surface 13 and the second side surface 16 of the base body 10.
[0071] The second external electrode 32 acts as an input electrode to the first coil 21. The second external electrode 32 may be provided only on the first main surface 11 of the base body 10, or it may be provided spanning the first main surface 11 and at least one of the second end surface 14 and the second side surface 16 of the base body 10.
[0072] The third external electrode 33 acts as an input electrode to the second coil 22. The third external electrode 33 may be provided only on the first main surface 11 of the base body 10, or it may be provided spanning the first main surface 11 and at least one of the second end surface 14 and the first side surface 15 of the base body 10.
[0073] The fourth external electrode 34 acts as an output electrode for the second coil 22. The fourth external electrode 34 may be provided only on the first main surface 11 of the base body 10, or it may be provided spanning the first main surface 11 and at least one of the first end surface 13 and the first side surface 15 of the base body 10.
[0074] As described above, the external electrodes are configured such that when current is supplied from the second external electrode 32 to the multilayer inductor 1, current flows counterclockwise through the first coil 21 when viewed in a plan view from the stacking direction, as shown in the perspective view of Figure 2. Similarly, when current is supplied from the third external electrode 33, current flows clockwise through the second coil 22 when viewed in a plan view, as shown in the perspective view of Figure 2. In other words, the direction of the current flowing through the first coil 21 and the direction of the current flowing through the second coil 22 are opposite. Furthermore, the direction of the magnetic flux generated by the first coil 21 is opposite to the direction of the magnetic flux generated by the second coil 22. To put this configuration in other words, when viewed from the output side electrodes (first external electrode 31 and fourth external electrode 34), the winding direction of the first coil 21 and the winding direction of the second coil 22 are opposite. This allows for optimal characteristics as an inductor used in a multiphase DC-DC converter.
[0075] A preferred arrangement of external electrodes is such that the second external electrode 32 and the third external electrode 33, which constitute the output electrode of the multilayer inductor 1, are arranged along one side that constitutes the outer edge of the base body 10. In other words, the second external electrode 32 and the third external electrode 33 are not arranged along the diagonal of the base body 10 in a plan view from the stacking direction. By arranging the external electrodes in this way, the output electrode and input electrode can be aligned on the same side of the base body, and the wiring on the substrate to the multilayer inductor 1 can be simplified.
[0076] The first external electrode 31, the second external electrode 32, the third external electrode 33, and the fourth external electrode 34 may each be composed of a conductive material such as Ag, Cu, and / or Pd. More preferably, a plating layer of one or more materials selected from the group consisting of Ni, Sn, Cu, and Au may be provided on the surface of these external electrodes. By providing a plating layer of the above materials, the electrodes can be properly mounted on a mounting substrate.
[0077] The thickness of the first external electrode 31, the second external electrode 32, the third external electrode 33, and the fourth external electrode 34 is preferably 5 μm or more and 100 μm or less, for example, 10 μm or more and 50 μm or less.
[0078] The thickness of external electrodes, such as the first external electrode 31, can be measured using the procedure described in "Thickness of the Non-magnetic Layer". That is, the sample is polished using the method described above, and the external electrode area is photographed with an SEM. In the obtained SEM image, one measurement is taken approximately in the center of the external electrode, and this measurement is defined as the thickness of the external electrode.
[0079] -Through-hole- The through-holes include a first through-hole 41, a second through-hole 42, a third through-hole 43, and a fourth through-hole 44. The first through-hole 41, the second through-hole 42, the third through-hole 43, and the fourth through-hole 44 are located inside the base body 10.
[0080] The first through-hole 41 connects the end of the main coil element 21a closest to the bottom surface (first main surface 11) of the base body 10 and the sub-coil element 21b in the first coil 21 at a position where the first through-hole 41 and the first external electrode 31 do not overlap when viewed from the stacking direction. The first through-hole 41 may extend along the stacking direction (for example, the height direction T). The first through-hole 41 may have a stacked structure.
[0081] Furthermore, the first through-hole 41 may be spaced apart from the first external electrode 31 when viewed from the stacking direction. Therefore, even if a sub-coil element 21b is provided in the stacked inductor 1 of this disclosure, the main coil element 21a and the sub-coil element 21b can be properly connected by the first through-hole 41.
[0082] The second through-hole 42 connects the other end of the main coil element 21a to the second external electrode 32 in the first coil 21. Preferably, the second through-hole 42 extends along the stacking direction (e.g., the height direction T). The second through-hole 42 may have a stacked structure.
[0083] The third through-hole 43 connects the end of the second coil conductor layer 52 closest to the bottom surface (first main surface 11) of the base body 10 with the third external electrode 33. Preferably, the third through-hole 43 extends along the stacking direction (e.g., the height direction T). The third through-hole 43 may have a stacked structure.
[0084] The fourth through-hole 44 connects the other end of the second coil 22 to the fourth external electrode 34. Preferably, the fourth through-hole 44 extends along the stacking direction (e.g., the height direction T). The fourth through-hole 44 may have a stacked structure.
[0085] Here, a preferred arrangement of the first through-holes 41 to the fourth through-holes 44 is such that the second through-holes 42 and the third through-holes 43, which are electrically connected to the output electrodes of the stacked inductor 1, are arranged along one side that constitutes the outer edge of the base body 10. In other words, the second through-holes 42 and the third through-holes 43 are not arranged along the diagonal of the base body 10 in a plan view from the stacking direction. By arranging the through-holes in this way, the output electrodes and input electrodes can be aligned in the same direction.
[0086] Furthermore, it is preferable that the length of the through-holes in the stacking direction is such that the length of the second through-hole 42 is longer than the length of the first through-hole 41, the length of the third through-hole 43 is longer than the length of the second through-hole 42, and the length of the fourth through-hole 44 is longer than the length of the third through-hole 43. Due to this relationship of through-hole lengths, the second coil 22, which is located further from the bottom surface of the base body 10 than the first coil 21 in the stacking direction, can be properly electrically connected to the external electrode.
[0087] Furthermore, in a preferred embodiment related to through-holes, the fourth through-hole 44 may be provided adjacent to three avoidance sections 60, the third through-hole 43 may be provided adjacent to two avoidance sections 60, the second through-hole 42 may be provided adjacent to one avoidance section 60, and the first through-hole 41 may be provided without being adjacent to an avoidance section 60. By avoiding the through-holes with the avoidance sections 60 in this way, the miniaturization of the multilayer inductor 1 is achieved.
[0088] Furthermore, in a preferred embodiment related to through-holes, the first through-hole 41 may be directly connected to the lower coil conductor of the first coil 21 winding, the second through-hole 42 may be directly connected to the upper coil conductor of the first coil 21 winding, the third through-hole 43 may be directly connected to the lower coil conductor of the second coil 22 winding, and the fourth through-hole 44 may be directly connected to the upper coil conductor of the second coil 22 winding. By directly connecting the through-holes to the coil conductors in this way, the miniaturization of the multilayer inductor 1 is achieved.
[0089] -Insulating layer- In a preferred configuration of the base body 10, an insulating layer 70 may be formed on the first main surface 11 (bottom surface) of the base body 10, covering the surface excluding the first to fourth external electrodes. The insulating layer 70 is a layer laminated on the first main surface 11 of the base body 10 (see Figure 4), and photoresist is one example. Furthermore, the insulating layer 70 has openings at positions corresponding to the four corners, and the first external electrode 31, second external electrode 32, third external electrode 33, and fourth external electrode 34 are embedded in these openings.
[0090] In the laminated inductor 1 of this disclosure, if an insulating layer 70 is provided and the subcoil element 21b of the first coil 21 is covered with the insulating layer 70, it is possible to prevent a short circuit between the laminated inductor 1 and the mounting substrate on which it is mounted.
[0091] <Second Embodiment of a Multilayer Inductor> Next, the multilayer inductor of the second embodiment will be described with reference to Figures 8, 9A, and 9B. Figure 8 is an exploded perspective view of the internal structure of the multilayer inductor of the second embodiment, Figure 9A is an explanatory diagram illustrating the wiring direction of the main coil element of the second embodiment, and Figure 9B is an explanatory diagram illustrating the wiring direction of the sub-coil element of the second embodiment. The multilayer inductor of the second embodiment differs from the multilayer inductor of the first embodiment described above in the configuration of the main coil element 21a and the sub-coil element 21b. The following description will focus on the differences from the multilayer inductor described in the above embodiment.
[0092] In this embodiment, the magnetic layer groups G1 to G7 shown in Figure 4 are as described in the multilayer inductor of the first embodiment.
[0093] In magnetic layer group G8, from the viewpoint of further increasing the inductance value by increasing the winding length of the first coil 21, the end of the main coil conductor layer 51a extends inward of the element 10 beyond the imaginary line C connecting the point on the inside of the first external electrode 31 and the point on the inside of the second external electrode 32 in a planar perspective view from the stacking direction.
[0094] In magnetic layer group G9, the first through-hole 41 is directly connected to the main coil conductor layer 51a, and is therefore positioned on the interior side of the element 10 relative to the imaginary line C in a planar perspective view from the stacking direction.
[0095] In magnetic layer group G10, one end of the subcoil conductor layer 51b is directly connected to the first through-hole 41, and therefore, corresponding to the position of the first through-hole 41, it extends inward from the imaginary line C in a planar perspective view from the stacking direction.
[0096] In the case of a multilayer inductor configured in this way, the overlapping region A between the main coil element 21a and the sub-coil element 21b can also be provided on the interior side of the element 10 beyond the imaginary line C, as shown in Figures 9A and 9B.
[0097] As described above, in this embodiment, one end of the main coil element 21a electrically connected to the first external electrode 31 of the laminated inductor 1 is positioned on the interior side of the base body 10 relative to the imaginary line C connecting the point on the interior side of the first external electrode 31 and the point on the interior side of the second external electrode 32. Therefore, the winding length of the main coil of the first coil 21 can be further increased, thereby increasing the number of turns, and thus the difference between the inductance value of the first coil 21 and the inductance value of the second coil 22 can be further reduced. Furthermore, by providing a sub-coil element 21b to the first coil 21, the winding length of the first coil 21 becomes even longer, which further reduces the difference in DC resistance value based on the wiring length of the second coil 22, which is located at a position away from the bottom surface of the base body 10.
[0098] <Third embodiment of a multilayer inductor> Next, a multilayer inductor of the third embodiment will be described with reference to Figure 10. Figure 10 is a schematic perspective view showing an example of the internal structure of the multilayer inductor of this disclosure.
[0099] The multilayer inductor 1 of this disclosure may include, in addition to the first coil 21 and second coil 22 described in the above-described multilayer inductor, a third coil 23 to a sixth coil 26 inside the base body 10. The third coil 23 and fifth coil 25 have substantially the same structure as the first coil 21, and the fourth coil 24 and sixth coil 26 have substantially the same structure as the second coil 22. That is, the second coil 22 is provided at a position further from the bottom surface of the base body 10 than the first coil 21 in the stacking direction, the fourth coil 24 is provided at a position further from the bottom surface of the base body 10 than the third coil 23 in the stacking direction, and the sixth coil 26 is provided at a position further from the bottom surface of the base body 10 than the fifth coil 25 in the stacking direction. Furthermore, the third coil 23 and fourth coil 24 are provided adjacent to the first coil 21 and second coil 22, and the fifth coil 25 and sixth coil 26 are provided adjacent to the third coil 23 and second coil 22. In other words, the third coil 23 and the fourth coil 24, as well as the fifth coil 25 and the sixth coil 26, are provided in a direction perpendicular to the stacking direction of the multilayer inductor, relative to the first coil 21 and the second coil 22.
[0100] The multilayer inductor 1 of this disclosure may include a fifth external electrode 35 and a sixth external electrode 36 electrically connected to the third coil. The end of the third coil conductor layer closest to the bottom surface may be connected to the fifth external electrode 35 by a fifth through-hole 45. The other end of the third coil conductor layer may be connected to the sixth external electrode 36 by a sixth through-hole 46.
[0101] The laminated inductor 1 of this disclosure may include a seventh external electrode 37 and an eighth external electrode 38 electrically connected to the fourth coil. The fourth coil may be positioned further from the bottom surface of the element 10 than the third coil in the lamination direction. The end of the fourth coil conductor layer closest to the bottom surface may be connected to the seventh external electrode 37 by a seventh through-hole 47. The other end of the fourth coil conductor layer may be connected to the eighth external electrode 38 by an eighth through-hole 48.
[0102] The case of the fifth coil 25 and the sixth coil 26 is the same as that of the third coil 23 and the fourth coil 24 described above, so the explanation is omitted.
[0103] As in this embodiment, by providing multiple coils adjacent to each other within the base body 10 perpendicular to the stacking direction, it is possible to contribute to increasing the current capacity and efficiency of the DC-DC converter.
[0104] 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.
[0105] The embodiments of the multilayer inductor described herein are as follows: <1> A base body with stacked magnetic layers, A first coil is provided inside the aforementioned body, and includes a plurality of first coil conductor layers in the stacking direction, and a second coil includes a plurality of second coil conductor layers in the stacking direction. The first coil comprises a first external electrode and a second external electrode electrically connected to the first coil, The first external electrode and the second external electrode are arranged on the bottom surface of the body. The second coil is provided at a position further from the bottom surface of the base body than the first coil in the stacking direction. The first coil comprises a main coil element consisting of a coil conductor whose stretching direction is perpendicular to the lamination direction, A sub-coil element is electrically connected in series with the main coil element and generates a magnetic flux in the opposite direction to the magnetic flux generated by the main coil element, A multilayer inductor consisting of the above. <2> The sub-coil element overlaps with a portion of the main coil element when viewed from the stacking direction. <1> The multilayer inductor described above. <3> The main coil element comprises multiple coil conductor layers. <1> or <2> The multilayer inductor described above. <4> One end of the subcoil element is directly connected to the first external electrode. The other end of the sub-coil element is electrically connected to the main coil element via a through-hole. <1> ~ <3> A multilayer inductor as described in any one of the following: <5> The distance between the sub-coil element and the main coil element in the stacking direction is longer than the interlayer distance between the first coil conductor layers in the stacking direction. <1> ~ <4> A multilayer inductor as described in any one of the following: <6> The sub-coil element is provided on the bottom surface of the base body. <1> ~ <5> A multilayer inductor as described in any one of the following: <7> The number of turns of the main coil element of the first coil is greater than the number of turns of the second coil. <1> ~ <6> A multilayer inductor as described in any one of the following: <8> The second coil is electrically connected to a third external electrode and a fourth external electrode, The third external electrode and the fourth external electrode are located on the bottom surface of the body. <1> ~ <7> A multilayer inductor as described in any one of the following: <9> An insulating layer is formed on the bottom surface of the aforementioned body, covering the surface excluding the first to fourth external electrodes. <8> The multilayer inductor described above. <10> A first through-hole is directly connected to one end of the main coil element, A second through-hole is directly connected to the other end of the main coil element, A third through-hole is directly connected to one end of the second coil, It comprises a fourth through-hole that is directly connected to the other end of the second coil, The first through-hole has one end directly connected to the main coil element and the other end directly connected to the sub-coil element. The second through-hole is directly connected to the second external electrode, The third through-hole is directly connected to the third external electrode, The fourth through-hole is directly connected to the fourth external electrode. <1> ~ <9> A multilayer inductor as described in any one of the following: <11> The length of the second through-hole in the stacking direction is longer than the length of the first through-hole in the stacking direction. The length of the third through-hole in the stacking direction is longer than the length of the second through-hole in the stacking direction. The length of the fourth through-hole in the stacking direction is longer than the length of the third through-hole in the stacking direction. <10> The multilayer inductor described above. <12> The inductance value of the first coil is within ±10% of the inductance value of the second coil. <1> ~ <11> A multilayer inductor as described in any one of the following: <13> The DC resistance of the first coil is within ±20% of the DC resistance of the second coil. <1> ~ <12> A multilayer inductor as described in any one of the following: <14> The direction of the magnetic flux generated by the first coil is opposite to the direction of the magnetic flux generated by the second coil. <1> ~ <13> A multilayer inductor as described in any one of the following: <15> One end of the main coil element, which is electrically connected to the first external electrode, is positioned on the interior side of the element beyond the imaginary line connecting the point on the interior side of the first external electrode and the point on the interior side of the second external electrode. <1> ~ <14> A multilayer inductor as described in any one of the following: <16> The through-holes that directly connect the main coil element and the sub-coil element are spaced apart from the corners of the base body in a planar perspective view. <1> ~ <15> A multilayer inductor as described in any one of the following: [Industrial applicability]
[0106] The multilayer inductor of this disclosure has multiple coils built into its base body and can be suitably used as an electronic component with small differences in electrical characteristics between the coils. [Explanation of Symbols]
[0107] 1. Multilayer Inductor 10 Base Body 11. First Main Surface 12 Second Main Surface 13 First end surface 14 Second end face 15 First aspect 16 Second aspect 21. First coil 21a Main coil element 21b Subcoil element 22 Second Coil 23. Third coil 24. Coil 4 25. 5th Coil 26. Coil 6 31 1st external electrode 32 2nd external electrode 33 Third external electrode 34 4th external electrode 35 5th external electrode 36 6th external electrode 37 7th external electrode 38 8th external electrode 41. First through hole 42. Second through hole 43. Third through hole 44. Fourth through hole 45. 5th through hole 46. 6th through hole 47. 7th through hole 48. 8th through hole 51 First coil conductor layer 51a Main coil conductor layer 51b Subcoil conductor layer 52 Second coil conductor layer 60 Avoidance part 65 Straight section 70 Insulating layer 80 via conductors A Overlapping area C virtual line G1-G10 Magnetic Layer Groups D1 Distance between subcoil element and maincoil element D2 Interlayer distance between conductor layers in the main coil S magnetic layer
Claims
1. A base body with stacked magnetic layers, A first coil is provided inside the aforementioned body and includes a plurality of first coil conductor layers in the stacking direction, and a second coil includes a plurality of second coil conductor layers in the stacking direction and has a winding configuration different from that of the first coil. The first coil comprises a first external electrode and a second external electrode electrically connected to the first coil, The first external electrode and the second external electrode are arranged on the bottom surface of the body. The second coil is provided at a position further from the bottom surface of the base body than the first coil in the stacking direction. The first coil comprises a main coil element consisting of a coil conductor whose lamination direction and stretching direction are perpendicular to each other, A sub-coil element is electrically connected in series with the main coil element and generates a magnetic flux in the opposite direction to the magnetic flux generated by the main coil element, thereby reducing the electrical characteristics between the first coil and the second coil. It consists of, The second coil is electrically connected to a third external electrode and a fourth external electrode, The third external electrode and the fourth external electrode are arranged on the bottom surface of the base body. A first through-hole is directly connected to one end of the main coil element, A second through-hole is directly connected to the other end of the main coil element, A third through-hole is directly connected to one end of the second coil, It comprises a fourth through-hole that is directly connected to the other end of the second coil, The first through-hole has one end directly connected to the main coil element and the other end directly connected to the sub-coil element. The second through-hole is directly connected to the second external electrode. The third through-hole is directly connected to the third external electrode, which is electrically connected to the second coil, and to the bottom surface of the body. The fourth through-hole is a multilayer inductor, in which the fourth external electrode, electrically connected to the second coil, is directly connected to the bottom surface of the base body.
2. The laminated inductor according to claim 1, wherein the sub-coil element overlaps with a portion of the main coil element when viewed from the stacking direction.
3. The laminated inductor according to claim 1, wherein the main coil element comprises a plurality of coil conductor layers.
4. The laminated inductor according to claim 1, wherein the distance between the sub-coil element and the main coil element in the lamination direction is longer than the interlayer distance between the first coil conductor layers in the lamination direction.
5. The laminated inductor according to claim 1, wherein the subcoil element is provided on the bottom surface of the main body.
6. The laminated inductor according to claim 1, wherein the number of turns of the main coil element of the first coil is greater than the number of turns of the second coil.
7. The laminated inductor according to claim 1, wherein an insulating layer is formed on the bottom surface of the base body, covering the surface excluding the first to fourth external electrodes.
8. The length of the second through-hole in the stacking direction is longer than the length of the first through-hole in the stacking direction. The length of the third through-hole in the stacking direction is longer than the length of the second through-hole in the stacking direction. The laminated inductor according to claim 1, wherein the length of the fourth through-hole in the stacking direction is longer than the length of the third through-hole in the stacking direction.
9. The multilayer inductor according to claim 1, wherein the inductance value of the first coil is within ±10% of the inductance value of the second coil.
10. The laminated inductor according to claim 1, wherein the DC resistance of the first coil is within ±20% of the DC resistance of the second coil.
11. The multilayer inductor according to claim 1, wherein the direction of the magnetic flux generated by the first coil is opposite to the direction of the magnetic flux generated by the second coil.
12. The stacked inductor according to claim 1, wherein one end of the main coil element electrically connected to the first external electrode is positioned inside the element beyond a virtual line connecting a point inside the first external electrode and a point inside the second external electrode.
Citation Information
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