Multilayer inductor

Abstract

Provided is a multilayer inductor in which a concentration of current density is mitigated and heat generation is reduced. A multilayer inductor according to the present disclosure comprises an element body 10 and an external electrode 20 provided to a mounting surface of the element body 10, wherein: the element body 10 is obtained by layering each of a coil conductor part CL, a magnetic part ML that is disposed around the coil conductor part CL and is configured by joining a plurality of metal magnetic particles, and through hole conductor parts TL that electrically connect each of the external electrode 20 and one end or the other end of the coil conductor part CL; a through hole conductor obtained by layering the through hole conductor parts TL comprises a coil-side through hole conductor part TL1 that is in contact with the coil conductor part CL and an external electrode-side through hole conductor part TL2 that is in contact with the external electrode 20; and the coil-side through hole conductor part TL1 projects further toward the inside of the element body 10 relative to the external electrode-side through hole conductor part TL2.

Description

Multilayer inductors

[0001] The present disclosure relates to laminated inductors.

[0002] Patent Document 1 discloses a coil component including a substrate containing a plurality of first metal magnetic particles, a coil conductor provided inside the substrate and having an end face exposed from the surface of the substrate, and an external electrode provided on the end face. The coil conductor described in Patent Document 1 has a winding portion wound around a coil axis and a lead portion extending from an end of the winding portion to the underside of the substrate.

[0003] Japanese Patent Application Laid-Open No. 2023-102541

[0004] The problem to be solved by the invention will be described in detail with reference to Fig. 10. The coil component shown in Fig. 10 includes a base body BD, a coil conductor CM', and an external electrode E', and the coil conductor CM' has a winding portion CC' wound around the coil axis and a lead-out portion TH' extending from one end or the other end of the winding portion CC' to the underside of the base body BD.

[0005] When a voltage is applied to the external electrode E', a current flows through the lead-out portion TH' along the thickness direction (T-axis direction). On the other hand, a current flows through the winding portion CC' in a direction perpendicular to the thickness direction. In other words, the current flows through the winding portion CC' at a 90° angle with respect to the lead-out portion TH'. As a result, current density concentrates in the connection region A' (particularly the region inside the corner) shown in FIG. 10 , which is formed by the winding portion CC' and the lead-out portion TH', causing heat generation. Heat generation is particularly noticeable in coil components that handle large currents, and it was necessary to alleviate the concentration of current density.

[0006] In view of the above, an object of the present disclosure is to provide a laminated inductor that alleviates current density concentration and reduces heat generation.

[0007] The laminated inductor of the present disclosure is a laminated inductor comprising: an element body; and an external electrode provided on a mounting surface of the element body, wherein the element body is laminated with: a coil conductor portion; a magnetic portion arranged around the coil conductor portion and formed by bonding a plurality of metal magnetic particles; and a through-hole conductor portion electrically connecting the external electrode to one end or the other end of the coil conductor portion, respectively; and the through-hole conductor formed by laminating the through-hole conductor portions comprises a coil-side through-hole conductor portion in contact with the coil conductor portion and an external electrode-side through-hole conductor portion in contact with the external electrode, and the coil-side through-hole conductor portion protrudes toward the inside of the element body relative to the external electrode-side through-hole conductor portion.

[0008] According to the laminated inductor of the present disclosure, the coil-side through-hole conductors in contact with the coil conductors protrude toward the inside of the element body relative to the external electrode-side through-hole conductors in contact with the external electrodes, thereby mitigating current density concentration inside corners formed by the coil conductors and the through-hole conductors, thereby providing a laminated inductor with reduced heat generation.

[0009] FIG. 1 is a perspective view of a laminated inductor according to the present disclosure. FIG. 2 is an exploded perspective view of the laminated inductor according to the present disclosure. FIG. 3 is a schematic cross-sectional view of the laminated inductor according to the first embodiment. FIG. 4 is a schematic cross-sectional view of a laminated inductor according to a modified example of the first embodiment. FIG. 5 is a schematic cross-sectional view of a laminated inductor according to a further modified example of the first embodiment. FIG. 6 is a schematic cross-sectional view of a laminated inductor according to a further modified example of the first embodiment. FIG. 7 is a schematic cross-sectional view of a laminated inductor according to a second embodiment. FIG. 8 is a schematic cross-sectional view of a laminated inductor according to a modified example of the second embodiment. FIG. 9 is a schematic cross-sectional view of a laminated inductor according to a third embodiment. FIG. 10 is a schematic cross-sectional view of a conventional laminated inductor.

[0010] The laminated inductor of the present disclosure will be described below. Note that the present disclosure is not limited to the following configurations and may be modified as appropriate within the scope of the present disclosure. In addition, a combination of multiple individual preferred configurations described below also constitutes the present disclosure.

[0011] 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 parts and coil conductor parts that make up the element body are stacked is referred to as the "stacking direction." Furthermore, a plan view refers to a plan view of the element body as seen from the top (height direction).

[0012] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, scale, etc. may differ from those of the actual product.

[0013] <Laminated Inductor of First Embodiment> First, a laminated inductor of a first embodiment of the present disclosure will be described with reference to Figures 1 to 6. The laminated inductor 1A includes an element body 10 and external electrodes 20 provided on the mounting surface of the element body 10. Each component will be described in detail below.

[0014] -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.

[0015] 1, the long side direction, short side direction, and height direction of the laminated 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.

[0016] The element body 10 shown in Fig. 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 and a second external electrode 22 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 multilayer inductor 1A. In the example shown in Fig. 1, the first external electrode 21 and the second external electrode 22 are provided so as to extend in the W direction, but this is not limited to this example, and the first external electrode 21 and the second external electrode 22 may be formed at diagonal corners of the first main surface 11, respectively.

[0017] FIG. 2 is an exploded perspective view schematically illustrating an example of the internal structure of a laminated inductor 1A according to the present disclosure. As shown in FIG. 2, the element body 10 includes a coil conductor portion CL, a magnetic portion ML, and a through-hole conductor portion TL, which are laminated together. In this embodiment, as shown in FIG. 2, the element body 10 is formed by laminating multilayer groups G1 to G8, with a first external electrode 21 and a second external electrode 22 formed on the underside of the multilayer group G8. Each of the multilayer groups G1 to G8 may also be formed by laminating multiple layers of the same pattern. Note that the boundaries between the layers in the laminate structure of the element body 10 may disappear.

[0018] (Stacking Group G1) The stacking group G1 has a magnetic part ML and may constitute the second main surface 12 of the element body 10 (see FIG. 1).

[0019] (Multilayer Group G2) The multilayer group G2 may include a coil conductor portion CL and a magnetic portion ML arranged around the coil conductor portion CL.

[0020] The coil conductor portion CL of the multilayer group G2 may be wound along the outer edge of the magnetic portion ML from a position corresponding to the first external electrode 21 to a position corresponding to the via conductor V of the multilayer group G3.

[0021] (Multilayer Group G3) The multilayer group G3 may include the coil side through-hole conductor portion TL1, the via conductor V, and the magnetic portion ML arranged around the via conductor V and the coil side through-hole conductor portion TL1.

[0022] The coil side through-hole conductor portion TL1 of the multilayer group G3 may electrically connect one end of the coil conductor portion CL of the multilayer group G2 to the external electrode side through-hole conductor portion TL2 of the multilayer group G4, and the via conductor V of the multilayer group G3 may electrically connect the other end of the coil conductor portion CL of the multilayer group G2 to one end of the coil conductor portion CL of the multilayer group G4.

[0023] (Multilayer Group G4) The multilayer group G4 may include a coil conductor portion CL, an external electrode side through-hole conductor portion TL2, and a magnetic portion ML arranged around the coil conductor portion CL and the external electrode side through-hole conductor portion TL2.

[0024] The coil conductor portion CL of the multilayer group G4 may be wound along the outer edge of the magnetic portion ML from a position corresponding to the via conductor V of the multilayer group G3 to a position corresponding to the via conductor V of the multilayer group G5. The coil conductor portion CL of the multilayer group G4 may include an avoidance portion A that avoids the external electrode side through-hole conductor portion TL2. By providing the avoidance portion A, it is possible to make the winding length of the coil conductor portion CL as long as possible while avoiding contact with the external electrode side through-hole conductor portion TL2.

[0025] The external electrode side through-hole conductor portion TL2 of the multilayer group G4 may be provided at a position corresponding to the coil side through-hole conductor portion TL1 of the multilayer group G3. The area of ​​the external electrode side through-hole conductor portion TL2 may be smaller than the area of ​​the coil side through-hole conductor portion TL1. The reason for this will be described in detail later when explaining the through-hole conductors TH.

[0026] (Multilayer Group G5) The multilayer group G5 may include an external electrode side through-hole conductor portion TL2, a via conductor V, and a magnetic portion ML arranged around the via conductor V and the coil side through-hole conductor portion TL1.

[0027] The external electrode side through-hole conductor portion TL2 of the multilayer group G5 may electrically connect the external electrode side through-hole conductor portions TL2 of the adjacent multilayer groups G4 and G6 to each other. Also, the via conductor V of the multilayer group G5 may electrically connect the other end of the coil conductor portion CL of the multilayer group G4 to one end of the coil conductor portion CL of the multilayer group G6.

[0028] (Multilayer Group G6) The multilayer group G6 may include a coil conductor portion CL, an external electrode side through-hole conductor portion TL2, and a magnetic portion ML arranged around the coil conductor portion CL and the external electrode side through-hole conductor portion TL2.

[0029] The coil conductor portion CL of the multilayer group G6 may be wound along the outer edge of the magnetic portion ML from a position corresponding to the via conductor V of the multilayer group G5 to a position corresponding to the coil side through-hole conductor portion TL1 of the multilayer group G7. The coil conductor portion CL of the multilayer group G6 may also have an avoidance portion A that avoids the external electrode side through-hole conductor portion TL2, similar to the coil conductor portion CL of the multilayer group G4.

[0030] The external electrode through-hole conductor portion TL2 of the multilayer group G6 may be provided at a position corresponding to the external electrode through-hole conductor portion TL2 of the multilayer group G5.

[0031] (Stacking group G7) The stacking group G7 may include an external electrode side through-hole conductor portion TL2 provided at a position corresponding to the first external electrode 21, a coil side through-hole conductor portion TL1 provided at a position corresponding to the second external electrode 22, and a magnetic portion ML arranged around the external electrode side through-hole conductor portion TL2 and the coil side through-hole conductor portion TL1.

[0032] (Stacking group G8) The stacking group G8 may include an external electrode side through-hole conductor portion TL2 provided at a position corresponding to the first external electrode 21, an external electrode side through-hole conductor portion TL2 provided at a position corresponding to the second external electrode 22, and a magnetic portion ML arranged around both external electrode side through-hole conductor portions TL2.

[0033] As described above, when the element body 10 has a multilayer structure including the multilayer groups G1 to G8, the degree of freedom in designing the multilayer inductor 1A is increased. For example, when manufacturing a multilayer inductor 1A including the first external electrode 21 and the second external electrode 22 on the bottom surface (first main surface 11) of the element body 10, it becomes easier to extend the coil conductor portion CL to the bottom surface side using the through-hole conductor portion TL. Note that the multilayer structure including the above-mentioned multilayer groups G1 to G8 may be laminated from the second main surface 12 side or the first main surface 11 side of the element body 10. Furthermore, the material constituting the through-hole conductor portion TL and / or the via conductor may be repeatedly printed by, for example, screen printing or the like until the via conductor reaches a desired thickness, or may be formed by an inkjet method or other known method.

[0034] As described above, the element body 10 contains the coil C formed by laminating coil conductor portions CL, the magnetic body M formed by laminating magnetic portions ML, and the through-hole conductors TH formed by laminating through-hole conductor portions TL. Each element constituting the element body 10 will be described in detail below.

[0035] - Coil - The coil C formed by stacking coil conductor portions CL may have a winding axis in the stacking direction. As described above, adjacent coil conductor portions CL in the stacking direction may be connected to each other via via conductors V. In the embodiment shown in FIG. 3, the number of turns may be 2.5 for the stacking groups G2, G4, and G6. Note that the number of turns is not limited to 2.5 as shown in the example.

[0036] The thickness of the coil conductor portion CL may be the same or different in each lamination group. The coil conductor portion CL may be made of a metal conductor such as Ag, Cu, and / or Pd. The coil conductor portion CL may be formed, for example, by printing a conductive paste on the magnetic portion ML.

[0037] -Magnetic Body- The magnetic body M (see FIG. 3), which is formed by stacking the magnetic sections ML, may contain metal magnetic particles made of a magnetic material. The metal magnetic particles may contain Fe and / or Si. More specifically, they may be Fe particles or Fe alloy particles. Examples of the Fe alloy include Fe-Si alloys, Fe-Si-Cr alloys, Fe-Si-Al alloys, Fe-Si-B-P-Cu-C alloys, and Fe-Si-B-Nb-Cu alloys. The metal magnetic particles may also contain impurities such as Cr, Mn, Cu, Ni, P, S, or Co that are not intended during manufacturing. The metal magnetic particles may also be contained in a magnetic paste. Elements that are more easily oxidized than Fe (e.g., Si, Cr, Al, Li, Zn, and Zr) may also be added to the magnetic paste.

[0038] The surfaces of the metal magnetic particles may be covered with an insulating coating. Covering the surfaces of the metal magnetic particles with an insulating coating can enhance the insulation between the metal magnetic particles, improve the withstand voltage of the inductor, and suppress eddy currents generated in the metal magnetic particles. Methods for forming the insulating coating on the surfaces of the metal magnetic particles include the sol-gel method and the mechanochemical method. The insulating coating may be made of an oxide of P, Si, or the like, zinc phosphate, or manganese phosphate. The insulating coating may also be an oxide film formed by oxidizing the surfaces of the metal magnetic particles with oxygen in the atmosphere, or an oxide film of an element that is more easily oxidized than Fe. The thickness of the insulating coating is preferably 1 nm or more and 50 nm or less, more preferably 1 nm or more and 30 nm or less, and even more preferably 1 nm or more and 20 nm or less. For example, the cross section obtained by polishing an inductor sample can be photographed using a transmission electron microscope (TEM), and the thickness of the insulating coating covering the surfaces of the metal magnetic particles can be measured from the resulting TEM photograph.

[0039] The average particle size of the metal magnetic particles in the magnetic body M (see FIG. 3 ) is preferably 1 μm or more and 30 μm or less, more preferably 1 μm or more and 20 μm or less, and even more preferably 1 μm or more and 10 μm or less. The average particle size of the metal magnetic particles in the magnetic body M can be measured by the following procedure. An inductor sample is cut to obtain a cross section. Specifically, the sample cross section is obtained by cutting the sample through the center of the element body so as to be perpendicular to the mounting surface and end surface of the laminated inductor. Multiple (e.g., five) regions (e.g., 130 μm × 100 μm) of the obtained cross section are photographed with a scanning electron microscope (SEM). 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 metal magnetic particles. The average of the obtained circle-equivalent diameters is defined as the average particle size of the metal magnetic particles.

[0040] When forming the element body 10, a heat treatment may be performed. In this case, the metal magnetic particles contained in the element body 10 have an oxide film on their surfaces. This oxide film is derived from the metal magnetic particles and is formed by heat treatment. In the element body 10, adjacent metal magnetic particles are joined to each other via the oxide film to form the magnetic section ML. As used herein, "composed of a plurality of metal magnetic particles joined together" may include not only a configuration in which the grain shape can be confirmed by SEM observation or the like, but also a configuration in which metal magnetic particles are used but a plurality of metal magnetic particles are united by heat treatment or the like to form a porous structure.

[0041] To further improve the strength of the element body 10, the element body 10 may be impregnated with a resin material after heat treatment. An example of a resin that can improve the element body strength is epoxy resin and / or phenol resin and / or silicone resin.

[0042] -Through-hole conductor- The through-hole conductor TH, which is formed by stacking the through-hole conductor portions TL, electrically connects the external electrode 20 to one end or the other end of the coil C. The through-hole conductor portions TL may be made of a metal conductor such as Ag, Cu, and / or Pd, for example. The through-hole conductor portions TL may be formed, for example, by printing a conductive paste on the magnetic portion ML.

[0043] A characteristic configuration of the multilayer inductor 1A of the present disclosure is that the through-hole conductors TH include coil-side through-hole conductor portions TL1 in contact with the coil conductor portions CL, and external electrode-side through-hole conductor portions TL2 in contact with the external electrodes 20. In Fig. 3 shown as an example, the coil-side through-hole conductor portions TL1 may be provided in the multilayer groups G3 and G7 shown in Fig. 2, and the external electrode-side through-hole conductor portions TL2 may be provided in the multilayer groups G4 to G8 shown in Fig. 2.

[0044] The coil side through-hole conductor portion TL1 protrudes toward the inside of the element body 10 relative to the external electrode side through-hole conductor portion TL2. In this specification, "protruding toward the inside of the element body 10" includes an embodiment in which, in a plan view, the coil side through-hole conductor portion TL1 extends more toward the center of the element body 10 than the external electrode side through-hole conductor portion TL2, an embodiment in which the coil side through-hole conductor portion TL1 extends more toward the center of the winding of the coil conductor portion CL than the external electrode side through-hole conductor portion TL2, or an embodiment in which the coil side through-hole conductor portion TL1 extends more toward the coil conductor portion CL that is on the same plane than the external electrode side through-hole conductor portion TL2. More specifically, in a cross-sectional view ( FIG. 3 ), the cross-sectional length L1 of the coil side through-hole conductor portion TL1 may be longer than the cross-sectional length L2 of the external electrode side through-hole conductor portion TL2 by 10 μm or more and 200 μm or less. In another aspect of the above configuration, the plane area of ​​the coil side through-hole conductor portion TL1 may be larger than the plane area of ​​the external electrode side through-hole conductor portion TL2. Specifically, in FIG. 2 , the plane area of ​​the coil side through-hole conductor portion TL1 may be 1.1 to 6.5 times the plane area of ​​the external electrode side through-hole conductor portion TL2.

[0045] In the multilayer inductor 1A of this embodiment, when the coil side through-hole conductor portion TL1 protrudes toward the inside of the element body 10 relative to the external electrode side through-hole conductor portion TL2, the coil side through-hole conductor portion TL1 is provided in the connection region A' where current density concentration occurs as shown in FIG. 10, as shown in FIG. 3. Therefore, with the multilayer inductor 1A of this embodiment, it is possible to alleviate current density concentration due to large current, and reduce heat generation in the multilayer inductor 1A. Furthermore, as a secondary effect, the size of the through-hole conductor TH is larger than the lead-out portion TH' shown in FIG. 10, thereby achieving low resistance. Therefore, the DC resistance (Rdc) of the multilayer inductor 1A can be reduced.

[0046] -External Electrode- The external electrode 20 is provided on the bottom surface of the element body 10. The external electrode 20 may include a first external electrode 21 and a second external electrode 22. Providing the external electrode 20 on the bottom surface (first main surface 11) of the element body 10 enables the multilayer inductor 1A to be properly mounted on a mounting board or the like.

[0047] The first external electrode 21 and the second external electrode 22 may each be provided only on the first main surface 11 of the element body 10, or may be provided across the first main surface 11 of the element body 10 and a surface adjacent to the first main surface 11 (one or two of the first end surface 13, the second end surface 14, the first side surface 15, and the second side surface 16).

[0048] The external electrodes 20 may be made of various materials, such as Cu, Au, and / or Ag. The external electrodes 20 may be formed by any method, but may be plated electrodes formed by plating (e.g., electroless plating or sputtering). As an example, a sintered electrode may be formed by applying a conductive paste containing Ag or the like. After the external electrodes 20 are formed, a plating layer of Ni, Sn, or the like may be formed on the external electrodes 20 by plating, resulting in a laminate structure of two or more layers.

[0049] <Preferred Aspect of the Laminated Inductor of First Embodiment> As a more specific feature of the laminated inductor 1A of the first embodiment (see FIGS. 3 to 6), the coil conductor portion CL may include a first coil conductor portion CL1 in contact with the coil-side through-hole conductor portion TL1, and a second coil conductor portion CL2 adjacent to the first coil conductor portion CL1 in the lamination direction. In other words, the number of laminations of the coil conductor portion CL may be two or more.

[0050] Furthermore, the bottom position P of the preferred coil-side through-hole conductor portion TL1 (see FIGS. 3 to 6 ) may be included in the corresponding region R1 extending from between the first coil conductor portion CL1 and the second coil conductor portion CL2 in the stacking direction to the bottom surface of the second coil conductor portion CL2. In the example of the multilayer inductor 1A shown in FIG. 3 , the bottom position P of the coil-side through-hole conductor portion TL1 coincides with the upper surface of the second coil conductor portion CL2. The bottom position P of the coil-side through-hole conductor portion TL1 is not limited to the embodiment shown in FIG. 3 . For example, as shown in FIG. 4 , the bottom position P of the coil-side through-hole conductor portion TL1 may be located within the magnetic portion ML between the first coil conductor portion CL1 and the second coil conductor portion CL2. Furthermore, as shown in FIG. 5 , the bottom position P of the coil-side through-hole conductor portion TL1 may be located so as to overlap the second coil conductor portion CL2 in the stacking direction. 6, the bottom position P of the coil side through-hole conductor portion TL1 may coincide with the bottom position of the second coil conductor portion CL2 in the stacking direction. In this way, the current density can be adjusted appropriately by appropriately changing the thickness of the coil side through-hole conductor portion TL1 and the shape of the magnetic portion ML in the vicinity of the coil side through-hole conductor portion TL1.

[0051] Furthermore, when the through-hole conductor portions TL are used to dissipate heat generated in the coil-side through-hole conductor portions TL1 from the mounting surface side, the second external electrode 22 side is closer to the mounting surface (first main surface 11) of the multilayer inductor 1A, making it easier to dissipate heat to the mounting board. On the other hand, the first external electrode 21 side is farther from the mounting surface (first main surface 11) of the multilayer inductor 1A, making it more difficult to dissipate heat to the mounting board. Therefore, the coil-side through-hole conductor portions TL1 on the first external electrode 21 side, which are farther from the mounting surface (first main surface 11) of the multilayer inductor 1A, may be made thicker to further alleviate the current density and reduce heat generation, as shown in FIG. 5 or 6 . In addition, since the second external electrode 22 side, which is closer to the mounting surface (first main surface 11) of the laminated inductor 1A, is relatively easy to dissipate heat, the coil side through-hole conductor portion TL1 on the second external electrode 22 side may be the same as or larger than the external electrode side through-hole conductor portion TL2.

[0052] As a more specific feature of the multilayer inductor 1A, as shown in Fig. 5 , the second coil conductor portion CL2 includes a thick portion T1 and a thin portion T2 extending from the thick portion T1 toward the coil-side through-hole conductor portion, and in plan view, a portion of the thin portion T2 of the second coil conductor portion CL2 may overlap with the coil-side through-hole conductor portion TL1. More specifically, the thin portion T2 of the second coil conductor portion CL2 may overlap with the coil-side through-hole conductor portion TL1 in an overlap region R2 shown in Fig. 5 . With this configuration, the characteristics (e.g., withstand voltage characteristics) of the multilayer inductor 1A can be ensured while making the thickness of the coil-side through-hole conductor portion TL1 as thick as possible (e.g., thicker than the thickness of the magnetic portion ML between the first coil conductor portion CL1 and the second coil conductor portion CL2) without changing the length L3 (see Fig. 5 ) of the second coil conductor portion CL2.

[0053] As a further specific feature of the laminated inductor 1A, as shown in FIG. 6, the coil conductor portion CL may further include a third coil conductor portion CL3 adjacent to the second coil conductor portion CL2 in the lamination direction.

[0054] 6 , the facing surface F1 of the second coil conductor portion CL2 facing the coil-side through-hole conductor portion TL1 may be located closer to the coil winding than the facing surface F2 of the third coil conductor portion CL3 facing the external electrode-side through-hole conductor portion TL2 in plan view. By specifying the facing surface F1 of the second coil conductor portion CL2 as described above, the thickness of the coil-side through-hole conductor portion TL1 can be increased while the second coil conductor portion CL2 is spaced apart from the coil-side through-hole conductor portion TL1 in the direction perpendicular to the stacking direction. This prevents unintended short circuits between the second coil conductor portion CL2 and the coil-side through-hole conductor portion TL1.

[0055] Furthermore, as shown in FIG. 6 , the shortest distance L4 between the coil-side through-hole conductor portion TL1 and the third coil conductor portion CL3 may be shorter than the shortest distance L5 between the coil-side through-hole conductor portion TL1 and the second coil conductor portion CL2. Here, the characteristics of the multilayer inductor 1A are better (e.g., L value) when the coil C has a relatively large number of turns of the coil conductor. In other words, it is preferable that the length of the coil conductor portion CL is as long as possible in the direction perpendicular to the lamination direction. To manufacture a coil conductor portion with as large a number of turns as possible, the second coil conductor portion CL2 and the coil-side through-hole conductor portion TL1 belong to the same lamination group. The distance between the second coil conductor portion CL2 and the coil-side through-hole conductor portion TL1 depends on the accuracy of pattern formation, such as screen printing. Therefore, the proximity of the second coil conductor portion CL2 to the coil-side through-hole conductor portion TL1 has been limited by the accuracy of pattern formation. Meanwhile, the coil-side through-hole conductor portion TL1 and the third coil conductor portion CL3 belong to different lamination groups. Therefore, it is possible to relatively easily bring the coil side through-hole conductor portion TL1 and the third coil conductor portion CL3 close to each other without relying on the accuracy of pattern formation such as screen printing. In view of the above, as shown in Fig. 6, good inductor characteristics can be obtained by making the shortest distance L4 between the coil side through-hole conductor portion TL1 and the third coil conductor portion CL3 shorter than the shortest distance L5 between the coil side through-hole conductor portion TL1 and the second coil conductor portion CL2.

[0056] <Laminated inductor of second embodiment> Next, a laminated inductor 1B of a second embodiment will be described with reference to Fig. 7 and Fig. 8. The laminated inductor 1B of the second embodiment differs from the laminated inductor 1A of the first embodiment in that an insulating portion IL is provided within the element body 10. The following description will focus on the differences from the laminated inductor 1A of the first embodiment.

[0057] In the multilayer inductor 1B of the second embodiment shown in FIG. 7 , an insulating portion IL extends from the second coil conductor portion CL2 in a direction perpendicular to the lamination direction. As described above, to obtain good inductor characteristics, a narrow spacing between the coil-side through-hole conductor portion TL1 and the second coil conductor portion CL2 is preferable. Therefore, by providing the insulating portion IL while narrowing the spacing between the coil-side through-hole conductor portion TL1 and the second coil conductor portion CL2, as in the multilayer inductor 1B of the second embodiment shown in FIG. 7 , it is possible to prevent a short circuit between the second coil conductor portion CL2 and the coil-side through-hole conductor portion TL1 and improve the withstand voltage. Note that the extending insulating portion IL does not need to be in contact with the coil-side through-hole conductor portion TL1 and / or the external electrode-side through-hole conductor portion TL2, as long as it is positioned within the shortest distance between the second coil conductor portion CL2 and the coil-side through-hole conductor portion TL1.

[0058] The second coil conductor portion CL2 of the multilayer inductor 1B of the second embodiment shown in FIG. 7 includes a thick portion T1 and a thin portion T2 extending from the thick portion T1 toward the coil-side through-hole conductor portion. An insulating portion IL may extend from an end portion TE of the thick portion T1 in a direction perpendicular to the lamination direction. This configuration allows the insulating portion IL to be provided over a wide area. The insulating portion IL may also extend over the second coil conductor portion CL2 of a uniform thickness, without providing the thick portion T1 and the thin portion T2 as shown in FIG. 7.

[0059] Furthermore, in the multilayer inductor 1B of the second embodiment shown in Fig. 7, the insulating portion IL may extend from the coil side through-hole conductor portion TL1 in a direction perpendicular to the lamination direction. Even with this configuration, it is possible to prevent a short circuit between the second coil conductor portion CL2 and the coil side through-hole conductor portion TL1. Note that the extending insulating portion IL does not need to be in contact with the second coil conductor portion CL2, as long as it is located between the second coil conductor portion CL2 and the coil side through-hole conductor portion TL1 at the shortest distance.

[0060] The insulating portion IL is preferably made of a material with higher insulating properties than the magnetic portion ML. For example, the insulating portion IL may contain at least one material selected from the group consisting of non-magnetic ferrite, zirconia, alumina, and glass. These insulating materials can ensure the voltage resistance characteristics of the laminated inductor.

[0061] In another embodiment of the insulating portion IL, the insulating portion IL may be made of the same material as the magnetic portion ML, but the particle size of the metal magnetic particles contained in the insulating portion IL may be smaller than the particle size of the metal magnetic particles contained in the magnetic portion ML. In other words, the insulating portion IL may contain small-diameter metal magnetic particles (e.g., 2 μm) smaller than the particle size of the metal magnetic particles contained in the magnetic portion ML (e.g., 5 μm). Generally, the smaller the particle size of the metal magnetic particles, the greater the number of layers of insulating coating per unit length, resulting in higher insulation properties. Therefore, by using small-diameter metal magnetic particles smaller than the particle size of the metal magnetic particles contained in the magnetic portion ML for the insulating portion IL, the voltage resistance characteristics of the laminated inductor can be ensured.

[0062] Furthermore, as another aspect of the insulating portion IL, the thickness of the insulating coating of the metal magnetic particles contained in the insulating portion IL may be made thicker than that of the metal magnetic particles contained in the magnetic portion ML, or the composition of the metal magnetic particles may be changed to a configuration with a higher resistance value.

[0063] As a modified example of the laminated inductor 1B of the second embodiment, as shown in Fig. 8, the insulating portion IL may extend at least to the outer edge CE of the second coil conductor portion CL2 in a plan view. Note that the insulating portion IL may be longer or shorter than the outer edge CE of the second coil conductor portion CL2. With this configuration, the insulating portion extending to the outer edge of the second coil conductor portion CL2 in a plan view can prevent an electrical short circuit to the second coil conductor portion CL2, thereby ensuring the voltage resistance characteristics of the laminated inductor.

[0064] Furthermore, as in a modified example of the laminated inductor 1B of the second embodiment shown in Fig. 8, insulating portions IL may be provided between adjacent coil conductor portions CL in the lamination direction. With this configuration, in the coil conductor portions CL electrically connected in the lamination direction by the via conductors V, contact between adjacent coil conductor portions CL can be appropriately prevented, and the withstand voltage characteristics of the laminated inductor can be ensured.

[0065] <Laminated Inductor of Third Embodiment> Next, a laminated inductor of a third embodiment will be described with reference to Fig. 9. The laminated inductor of the third embodiment differs from the laminated inductor of the first embodiment in that two or more coils are arranged within the element body 10. The following description will focus on the differences from the description of the laminated inductor of the first embodiment.

[0066] 9, a first coil C1 and a second coil C2 disposed below the first coil C1 are provided within the element body 10. The first coil C1 is composed of a first coil conductor portion CL1 to a third coil conductor portion CL3, and the second coil C2 is composed of a fourth coil conductor portion CL4 to a sixth coil conductor portion CL6.

[0067] 9, one end of the first coil C1 is electrically connected to the first external electrode 21 via a through-hole conductor TH, and the other end is electrically connected to the second external electrode 22 via a through-hole conductor TH. Similarly, one end of the second coil C2 is electrically connected to the third external electrode (not shown) via a through-hole conductor (not shown), and the other end is electrically connected to the fourth external electrode (not shown) via a through-hole conductor (not shown).

[0068] As described in <Laminated Inductor of First Embodiment>, each through-hole conductor TH includes a coil-side through-hole conductor portion TL1 in contact with the coil conductor portion CL, and an external electrode-side through-hole conductor portion TL2 in contact with the external electrode 20. The coil-side through-hole conductor portion TL1 protrudes toward the inside of the element body 10 relative to the external electrode-side through-hole conductor portion TL2. Therefore, even in the multilayer inductor 1C of the third embodiment, the coil-side through-hole conductor portion TL1 can mitigate current density concentration due to large currents, thereby reducing heat generation in the multilayer inductor 1C. Furthermore, the DC resistance (Rdc) of the multilayer inductor 1C can be reduced.

[0069] Furthermore, the laminated inductor 1C of the third embodiment may also be provided with the insulating portion IL described in <Laminated inductor of the second embodiment>. The insulating portion IL shown in Fig. 9 extends from the end TE of the thick portion T1 in a direction perpendicular to the lamination direction, but is not limited to this. The insulating portion IL may be provided between coil conductor portions CL adjacent in the lamination direction, as shown in a modified example of the laminated inductor of the second embodiment (Fig. 8).

[0070] 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.

[0071] The aspects of the laminated inductor of the present disclosure are as follows: <1> A laminated inductor comprising an element body and an external electrode provided on a mounting surface of the element body, wherein the element body is laminated with a coil conductor portion, a magnetic portion disposed around the coil conductor portion and formed by bonding a plurality of metal magnetic particles, and through-hole conductor portions electrically connecting the external electrode to one end or the other end of the coil conductor, wherein a through-hole conductor formed by laminating the through-hole conductor portions comprises a coil-side through-hole conductor portion in contact with the coil conductor portion and an external electrode-side through-hole conductor portion in contact with the external electrode, and the coil-side through-hole conductor portion protrudes toward the inside of the element body with respect to the external electrode-side through-hole conductor portion. <2> The laminated inductor according to <1>, wherein the coil conductor comprises a first coil conductor in contact with the coil-side through-hole conductor and a second coil conductor adjacent to the first coil conductor in the stacking direction, and the bottom surface of the coil-side through-hole conductor is located in a corresponding region from between the first coil conductor and the second coil conductor to the bottom surface of the second coil conductor. <3> The laminated inductor according to <1> or <2>, wherein the coil conductor comprises a first coil conductor in contact with the coil-side through-hole conductor and a second coil conductor adjacent to the first coil conductor in the stacking direction, and the second coil conductor comprises a thick portion and a thin portion extending from the thick portion toward the coil-side through-hole conductor, and a part of the thin portion overlaps with the coil-side through-hole conductor in a plan view. <4> A laminated inductor described in any one of <1> to <3>, wherein the coil conductor portion includes a first coil conductor portion in contact with the coil side through hole conductor portion, a second coil conductor portion adjacent to the first coil conductor portion in the stacking direction, and a third coil conductor portion adjacent to the second coil conductor portion in the stacking direction, and the opposing surface of the second coil conductor portion facing the coil side through hole conductor portion is located more inward than the opposing surface of the third coil conductor portion facing the external electrode side through hole conductor portion in a planar view.<5> The multilayer inductor according to any one of <1> to <4>, wherein the coil conductor comprises a first coil conductor in contact with the coil side through-hole conductor, a second coil conductor adjacent to the first coil conductor in the stacking direction, and a third coil conductor adjacent to the second coil conductor in the stacking direction, and the shortest distance between the coil side through-hole conductor and the third coil conductor is shorter than the shortest distance between the coil side through-hole conductor and the second coil conductor. <6> The multilayer inductor according to any one of <1> to <5>, wherein the coil conductor comprises a first coil conductor in contact with the coil side through-hole conductor and a second coil conductor adjacent to the first coil conductor in the stacking direction, and an insulating portion extends from the second coil conductor in a direction perpendicular to the stacking direction. <7> The multilayer inductor according to any one of <1> to <6>, wherein the coil conductor comprises a first coil conductor in contact with the coil-side through-hole conductor and a second coil conductor adjacent to the first coil conductor in the stacking direction, and wherein an insulating portion extends from the coil-side through-hole conductor in a direction perpendicular to the stacking direction. <8> The multilayer inductor according to <6> or <7>, wherein the insulating portion extends to the outer edge of the second coil conductor in a plan view. <9> The multilayer inductor according to any one of <6> to <8>, wherein the insulating portion is provided between the coil conductors adjacent in the stacking direction. <10> The multilayer inductor according to any one of <6> to <9>, wherein the insulating portion contains at least one material selected from the group consisting of non-magnetic ferrite, zirconia, and glass. <11> The multilayer inductor according to any one of <6> to <10>, wherein the insulating portion contains small-diameter metal magnetic particles having a particle size smaller than that of the metal magnetic particles contained in the magnetic portion. <12> The laminated inductor according to any one of <1> to <11>, wherein the coil conductors are used to arrange two or more coils in the lamination direction.

[0072] The laminated inductor of the present disclosure can be suitably used as an electronic component that alleviates current density concentration and reduces heat generation.

[0073] 1A, 1B, 1C Multilayer inductor 10 Element body 20 External electrode 21 First external electrode 22 Second external electrode C Coil C1 to C2 First and second coils CL Coil conductor portion CL1 to CL3 First to third coil conductor portions A Avoidance portion T1 Thick portion TE End portion T2 Thin portion M Magnetic body ML Magnetic portion TH Through-hole conductor TL Through-hole conductor portion TL1 Coil side through-hole conductor portion TL2 External electrode side through-hole conductor portion IL Insulation portion V Via conductor

Claims

1. A laminated inductor comprising an element body and an external electrode provided on a mounting surface of the element body, wherein the element body is laminated with: a coil conductor portion; a magnetic portion arranged around the coil conductor portion and formed by bonding a plurality of metal magnetic particles; and through-hole conductor portions electrically connecting the external electrode to one end or the other end of the coil conductor portion, wherein the through-hole conductor formed by laminating the through-hole conductor portions comprises a coil-side through-hole conductor portion in contact with the coil conductor portion and an external electrode-side through-hole conductor portion in contact with the external electrode, and the coil-side through-hole conductor portion protrudes toward the inside of the element body relative to the external electrode-side through-hole conductor portion.

2. A laminated inductor as described in claim 1, wherein the coil conductor comprises a first coil conductor in contact with the coil side through-hole conductor, and a second coil conductor adjacent to the first coil conductor in the lamination direction, and the bottom surface of the coil side through-hole conductor is located in a corresponding area extending from between the first coil conductor and the second coil conductor to the bottom surface of the second coil conductor.

3. A laminated inductor according to claim 1 or 2, wherein the coil conductor comprises a first coil conductor in contact with the coil side through hole conductor and a second coil conductor adjacent to the first coil conductor in the lamination direction, and the second coil conductor comprises a thick portion and a thin portion extending from the thick portion towards the coil side through hole conductor, and a part of the thin portion overlaps with the coil side through hole conductor in a plan view.

4. A multilayer inductor according to any one of claims 1 to 3, wherein the coil conductor comprises a first coil conductor in contact with the coil side through hole conductor, a second coil conductor adjacent to the first coil conductor in the stacking direction, and a third coil conductor adjacent to the second coil conductor in the stacking direction, and the opposing surface of the second coil conductor that faces the coil side through hole conductor is located more inward than the opposing surface of the third coil conductor that faces the external electrode side through hole conductor in a plan view.

5. A multilayer inductor according to any one of claims 1 to 4, wherein the coil conductor comprises a first coil conductor in contact with the coil side through hole conductor, a second coil conductor adjacent to the first coil conductor in the stacking direction, and a third coil conductor adjacent to the second coil conductor in the stacking direction, and the shortest distance between the coil side through hole conductor and the third coil conductor is shorter than the shortest distance between the coil side through hole conductor and the second coil conductor.

6. A multilayer inductor according to any one of claims 1 to 5, wherein the coil conductor comprises a first coil conductor in contact with the coil-side through-hole conductor, and a second coil conductor adjacent to the first coil conductor in the stacking direction, and an insulating portion extends from the second coil conductor in a direction perpendicular to the stacking direction.

7. A multilayer inductor according to any one of claims 1 to 6, wherein the coil conductor comprises a first coil conductor in contact with the coil-side through-hole conductor, and a second coil conductor adjacent to the first coil conductor in the stacking direction, and an insulating portion extends from the coil-side through-hole conductor in a direction perpendicular to the stacking direction.

8. The laminated inductor according to claim 6 or 7, wherein the insulating portion extends to the outer edge of the second coil conductor portion in a plan view.

9. The laminated inductor according to any one of claims 6 to 8, wherein the insulating portion is provided between the coil conductor portions adjacent in the lamination direction.

10. The laminated inductor according to any one of claims 6 to 9, wherein the insulating portion comprises at least one material selected from the group consisting of non-magnetic ferrite, zirconia, alumina, and glass.

11. A laminated inductor according to any one of claims 6 to 10, wherein the insulating portion contains small-diameter metal magnetic particles having a particle size smaller than that of the metal magnetic particles contained in the magnetic portion.

12. The multilayer inductor according to any one of claims 1 to 11, wherein two or more coils are arranged in the stacking direction by the coil conductor portion.

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