Multilayer inductor

Abstract

Provided is a multilayer inductor in which coil conductor layers have improved internal states on the sides adjacent to metal magnetic bodies, thereby achieving reduction in resistance of the coil conductor layers, and an enhancement in skin effect. A multilayer inductor according to the present disclosure comprises an element body 10 having metal magnetic bodies M obtained by laminating metal magnetic layers ML containing metal magnetic particles and coils (a first coil C1, a second coil C2) obtained by laminating coil conductor layers CL in the lamination direction of the metal magnetic layers ML. Each coil conductor layer CL includes: outer conductor layer parts CLo located adjacent to the metal magnetic layers ML in the lamination direction, and an inner conductor layer part CLi located inward of the outer conductor layer parts CLo and adjacent to the outer conductor layer parts CLo. The number of voids in the outer conductor layer part CLo is less than the number of voids in the inner conductor layer part CLi.

Description

Multilayer inductors

[0001] The present disclosure relates to laminated inductors.

[0002] Patent Document 1 discloses a multilayer inductor in which a plurality of coil conductor layers (Ag) are stacked with magnetic layers (Ni-Cu-Zn ferrite) interposed therebetween, and the actual surface length per unit length of the coil conductor layers is in the range of 1≦(actual surface length / unit length)≦1.3. With this multilayer inductor, the surface smoothness of the conductor layers is improved to shorten the effective surface length of the coil portion, so that even if current flows concentratedly on the surface of the coil portion due to the skin effect, the resistance value can be reduced and a decrease in the Q value can be suppressed.

[0003] Japanese Patent Application Laid-Open No. 2004-39957

[0004] In recent years, metal magnetic particles have been used in the magnetic layer. However, when metal magnetic particles are used, there is a risk that the magnetic properties of the metal magnetic material will deteriorate if the heat treatment (e.g., sintering) temperature is high. Therefore, it is not possible to use a high heat treatment temperature like when ferrite is used in the magnetic layer. Furthermore, if the heat treatment temperature is low, the conductor for the coil tends to be insufficiently sintered.

[0005] If the coil conductor is not sintered properly, the Q value decreases due to the skin effect when a high-frequency current flows through the coil conductor, and the resistance of the coil conductor increases. Specifically, if the coil conductor is not sintered properly, voids P exist throughout the entire coil conductor CD as shown in Figure 7, causing the Q value to decrease due to the skin effect and the resistance of the coil conductor to increase.

[0006] In view of these points, the present disclosure aims to provide a laminated inductor that improves the internal state of the coil conductor layer adjacent to the metal magnetic body, thereby reducing the resistance of the coil conductor layer and improving the skin effect.

[0007] The laminated inductor according to the present disclosure comprises an element body having a metal magnetic body in which metal magnetic layers containing metal magnetic particles are laminated, and a coil in which coil conductor layers are laminated in the lamination direction of the metal magnetic layers, wherein the coil conductor layer comprises an outer conductor layer portion adjacent to the metal magnetic layer in the lamination direction, and an inner conductor layer portion located inside the outer conductor layer portion and adjacent to the outer conductor layer portion, and the amount of voids in the outer conductor layer portion is smaller than the amount of voids in the inner conductor layer portion.

[0008] According to the laminated inductor of the present disclosure, the internal state of the coil conductor layer adjacent to the metal magnetic body can be improved, and the resistance of the coil conductor layer can be reduced and the skin effect can be improved.

[0009] FIG. 1 is a perspective view of a laminated inductor according to the present disclosure. FIG. 2 is an exploded perspective view of a laminated inductor according to the present disclosure. FIG. 3 is a schematic cross-sectional view of a laminated inductor according to the present disclosure. FIG. 4 is an SEM photograph of a laminated inductor according to the present disclosure. FIG. 5 is a schematic cross-sectional view of a laminated inductor according to the present disclosure. FIG. 6 is an SEM photograph of a laminated inductor according to the present disclosure. FIG. 7 is a schematic cross-sectional view of a conventional laminated inductor. FIG. 8 is a manufacturing flow diagram showing a manufacturing process for a laminated inductor according to the present disclosure.

[0010] The laminated inductor and the method for manufacturing the laminated inductor according to the present disclosure will be described in detail below. While the description will be made with reference to the drawings as necessary, the contents shown are merely shown as schematic and illustrative examples to facilitate understanding of the present disclosure, and the appearance and dimensional ratios may differ from those of the actual product. The drawings shown below are schematic diagrams, and the dimensions, aspect ratios, and other scales may differ from those of the actual product.

[0011] In this specification, terms indicating the relationship between elements (e.g., "parallel," "orthogonal," etc.) and terms indicating the shape of elements not only refer to the strict literal form, but also refer to a range of substantial equivalence, for example, a range including a difference of about a few percent. Note that in this specification, the direction in which the magnetic layers and coil conductor layers constituting 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] <Laminated Inductor of the Present Disclosure> The laminated inductor 1 of the present disclosure includes an element body 10 and an external electrode 20 provided on the mounting surface of the element body 10 .

[0013] [Element Body] The element body 10 has, for example, a hexahedral shape having six sides. As an example, it may have a rectangular parallelepiped shape or a substantially rectangular parallelepiped shape. The corners and ridges of the element body 10 may be rounded. A corner is a portion where three sides of the element body 10 intersect, and a ridge is a portion where two sides of the element body 10 intersect.

[0014] 1, the long side direction, short side direction, and height direction of the laminated inductor 1 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.

[0015] 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. In the example shown in Fig. 1, a first external electrode 21, a second external electrode 22, a third external electrode 23, and a fourth external electrode 24 are formed on the first main surface 11 of the element body 10, and the first main surface 11 of the element body 10 corresponds to the mounting surface of the laminated inductor 1 (the bottom surface of the element body).

[0016] Fig. 2 is an exploded perspective view schematically showing an example of the internal structure of the laminated inductor 1 of the present disclosure. As shown in Fig. 2, the element body 10 is formed by laminating a coil conductor layer CL, a metal magnetic layer ML containing metal magnetic particles, and a through-hole conductor TH. As an example, two coils (a first coil C1 and a second coil C2) are provided inside the element body 10. The number of coils provided inside the element body 10 may be three or more, or may be one.

[0017] The element body 10 is formed by stacking multilayer groups G1 to G7, with the first external electrode 21 to the fourth external electrode 24 formed below the multilayer group G7. The boundaries between the layers in the multilayer structure of the element body 10 may disappear. Each of the multilayer groups G1 to G7 may be configured by stacking multiple layers to achieve a desired thickness.

[0018] The lamination group G1 has a metal magnetic layer ML and constitutes the second main surface 12 of the element body 10 (see FIG. 1).

[0019] The multilayer group G2 and the multilayer group G3 are provided to configure the second coil C2. That is, the coil conductor layers CL are stacked to configure the second coil C2. The coil conductor layers CL of the multilayer group G2 and the coil conductor layers CL of the multilayer group G3 may be connected to each other by via conductors (not shown). Furthermore, the multilayer groups G2 and G3 of the present disclosure may each be configured by stacking multiple layers.

[0020] One end of the second coil C2 is provided with a third through-hole conductor TH3 electrically connected to the third external electrode 23, and the other end of the second coil C2 is provided with a fourth through-hole conductor TH4 electrically connected to the fourth external electrode 24. A metal magnetic layer ML is disposed around the coil conductor layer CL, the third through-hole conductor TH3, and the fourth through-hole conductor TH4.

[0021] The multilayer group G4 and the multilayer group G5 are provided to configure the first coil C1. That is, the coil conductor layers CL are stacked to configure the first coil C1. The coil conductor layers CL of the multilayer group G4 and the coil conductor layers CL of the multilayer group G5 may be connected to each other by via conductors (not shown). Furthermore, the multilayer group G4 and the multilayer group G5 of the present disclosure may be configured by stacking multiple layers.

[0022] One end of the first coil C1 is provided with a first through-hole conductor TH1 electrically connected to the first external electrode 21, and the other end of the first coil C1 is provided with a second through-hole conductor TH2 electrically connected to the second external electrode 22. A metal magnetic layer ML is disposed around the coil conductor layer CL and the first through-hole conductors TH1 to TH4.

[0023] The multilayer group G6 and the multilayer group G7 are provided with first through-hole conductors TH1 to 4th through-hole conductors TH4 corresponding to the arrangement of the first external electrodes 21 to 4th external electrodes 24. A metal magnetic layer ML is arranged around the first through-hole conductors TH1 to 4th through-hole conductors TH4. As shown in FIG. 2 , by making the planar area of ​​the first through-hole conductors TH1 to 4th through-hole conductors TH4 of the multilayer group G7 larger than the planar area of ​​the first through-hole conductors TH1 to 4th through-hole conductors TH4 of the multilayer group G6, the alignment of the through-hole conductors can be facilitated.

[0024] As described above, when the element body 10 has a multilayer structure including the multilayer groups G1 to G7, the degree of freedom in designing the multilayer inductor 1 is increased. For example, when manufacturing a multilayer inductor 1 including the first external electrode 21 to the fourth external electrode 24 on the bottom surface (first main surface 11) of the element body 10, it becomes easier to draw the coils (first coil C1, second coil C2) to the bottom surface side using through-hole conductors. Note that the multilayer structure including the above-mentioned multilayer groups G1 to G7 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 conductors TH and / or the via conductors may be repeatedly printed in sequence by, for example, screen printing or the like until the via conductors reach the desired thickness, or they may be formed by sputtering, inkjet printing, or other known methods.

[0025] As described above, the element body 10 includes a metal magnetic body M formed by laminating metal magnetic layers ML, coils (first coil C1 and second coil C2) formed by laminating coil conductor layers CL, and through-hole conductors TH. Each element constituting the element body 10 will be described in detail below.

[0026] -Metal Magnetic Material- The metal magnetic material M formed by laminating metal magnetic layers ML may contain metal magnetic particles made of a metal 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 Fe alloys include Fe-Si alloys, Fe-Cr alloys, Fe-Si-Cr alloys, Fe-Si-Al alloys, Fe-Si-B-P-Cu-C alloys, and Fe-Si-B-Nb-Cu alloys. The 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. Therefore, the metal magnetic particles may contain elements (e.g., Cr, Al, Li, Zn, Zr) that are more easily oxidized than the Fe added during magnetic paste production.

[0027] The surfaces of the above-mentioned metal magnetic particles may be covered with an insulating coating. Covering the surfaces of the metal magnetic particles with an insulating coating can improve the insulation between the metal magnetic particles, improving the withstand voltage of the inductor and suppressing 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 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 with a scanning electron microscope (SEM), and the thickness of the insulating coating covering the surfaces of the metal magnetic particles can be measured from the obtained SEM photograph.

[0028] The average particle size of the metal magnetic particles in the metal magnetic body M is preferably 0.2 μm or more and 50 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 metal magnetic body M can be measured by the following procedure. An inductor sample is cut to obtain a cross section of the sample. Specifically, the sample cross section is obtained by cutting 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 using an SEM, and the obtained SEM images are analyzed using image analysis software (e.g., image analysis software WinROOF2021 (manufactured by Mitani Corporation)) to determine the circle-equivalent diameter of the metal magnetic particles. The average of the obtained circle-equivalent diameters is taken as the average particle size of the metal magnetic particles.

[0029] 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 metal magnetic layer ML. As used herein, "composed of a plurality of joined metal magnetic particles" 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 the plurality of metal magnetic particles are mixed together by heat treatment or the like to form a dense structure (for example, a sintered body).

[0030] In order to further improve the strength of the element body 10, the element body 10 may be impregnated with a resin material after firing the element body 10. As an example of a resin that increases the strength of the element body, an epoxy resin and / or a phenol resin and / or a silicone resin may be used.

[0031] - Coils - The coils (first coil C1 and second coil C2) formed by stacking coil conductor layers CL may have a winding axis in the stacking direction. As described above, adjacent coil conductor layers CL in the stacking direction may be connected via via conductors. In the embodiment shown in FIG. 2, the first coil C1 is formed by the stacking group G4 and the stacking group G5. The second coil C2 is formed by the stacking group G2 and the stacking group G3.

[0032] The thickness of the coil conductor layer CL may be the same or different in each lamination group. The coil conductor layer CL may contain, as an example of a material, Ag, and may further contain a metal conductor such as Cu and / or Pd. More specifically, the material of the coil conductor layer CL may be softer than the metal magnetic material constituting the above-mentioned metal magnetic body M. The coil conductor layer CL may be formed, for example, by printing a conductive paste on the above-mentioned metal magnetic layer ML.

[0033] Each coil conductor layer CL may include an outer conductor layer portion CLo adjacent to the metal magnetic layer ML in the stacking direction, and an inner conductor layer portion CLi located inside the outer conductor layer portion CLo and adjacent to the outer conductor layer portion CLo (see Figures 3 and 5).

[0034] In this specification, the boundary between the outer conductor layer portion CLo and the inner conductor layer portion CLi is set as follows: (1) A cross section is prepared by cutting the element body 10 in the thickness direction along the longitudinal direction of the element body 10 from the mounting surface side at a position passing through the winding axis of the coil. (2) This cross section is photographed by SEM and / or EDX with a field of view (approximately 400 to 600 times) large enough to confirm the entire thickness of the coil conductor layer CL (see FIGS. 4 and 6 for examples). (3) As shown in FIGS. 3 and 4 , when the cross section of the coil conductor layer CL is observed, it can be seen from the amount of void P that the coil conductor layer CL has, in the thickness direction, an outer conductor layer portion CLo adjacent to the metal magnetic layer ML and an inner conductor layer portion CLi adjacent to the outer conductor layer portion CLo. In the illustrated example, the thickness L1 of the inner conductor layer portion CLi and the total thickness (0.5L1, 0.5L1) of the outer conductor layer portion CLo are approximately equal to each other, but this is not limited to this.

[0035] In the laminated inductor 1 of the present disclosure, the amount of the gap P in the outer conductor layer portion CLo is smaller than the amount of the gap P in the inner conductor layer portion CLi (see FIGS. 4 and 6). In this specification, the amount of the gap P is determined by binarizing an image of the coil conductor layer CL and calculating the area of ​​the gap P in the inner conductor layer portion CLi and the area of ​​the gap P in the outer conductor layer portion CLo.

[0036] Therefore, compared to a conventional inductor in which a gap P exists over the entire area of ​​the coil conductor CD as shown in FIG. 7 , the laminated inductor 1 of the present disclosure has a smaller amount of gap in the outer conductor layer portion CLo, which makes it possible to improve the reduction in the Q value caused by the skin effect and to reduce the resistance of the coil.

[0037] In a preferred embodiment of the laminated inductor 1, the inner conductor layer portions CLi may be sandwiched between the outer conductor layer portions CLo in the stacking direction. With this configuration, the inner conductor layer portions CLi are sandwiched between the outer conductor layer portions CLo with few gaps, which makes it possible to more appropriately improve the reduction in the Q value caused by the skin effect at the boundary between the coil conductor layer CL and the metal magnetic layer ML.

[0038] 5 and 6, the thickness of the outer conductor layer portion CLo (0.05L2, 0.05L2) may be 0.1 times the thickness L2 of the inner conductor layer portion CLi. Note that the thickness of the outer conductor layer portion CLo in this specification refers to the total thickness of the outer conductor portions CLo on both sides of the inner conductor layer portion CLi in the stacking direction. Setting the outer conductor layer portion CLo and the inner conductor layer portion CLi in this manner reduces the amount of voids in the outer conductor layer portion CLo, further improving the reduction in the Q value due to the skin effect. Therefore, it is preferable that the thickness of the outer conductor layer portion CLo be 0.1 to 1 times the thickness of the inner conductor layer portion CLi.

[0039] 3 and 4, the area of ​​the gap P in the inner conductor layer portion CLi is 1.2 times the area of ​​the gap P in the outer conductor layer portion CLo, and in the embodiment shown in FIGS. 5 and 6, the area of ​​the gap P in the inner conductor layer portion CLi is three times the area of ​​the gap P in the outer conductor layer portion CLo. Note that the area of ​​the gap P in the outer conductor layer portion CLo referred to in this specification refers to the total area of ​​the gaps P in the outer conductor portions CLo on both sides of the inner conductor layer portion CLi in the stacking direction. Therefore, in a preferred embodiment of the multilayer inductor 1 of the present disclosure, when the coil conductor layer CL is viewed in cross section, the area of ​​the gap P in the inner conductor layer portion CLi may be 1.2 to 3 times the area of ​​the gap P in the outer conductor layer portion CLo. This configuration can favorably reduce the resistance of the coil conductor layer and improve the surface effect.

[0040] -Through-Hole Conductors- The through-hole conductors TH (first through-hole conductor TH1 to fourth through-hole conductor TH4) electrically connect the external electrode 20 to one end or the other end of the coil (first coil C1, second coil C2). The through-hole conductors TH may be made of a metal conductor such as Ag, Cu, and / or Pd, for example. The through-hole conductor layer TL may be formed, for example, by printing a conductive paste on the metal magnetic layer ML.

[0041] [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 to a fourth external electrode 24. The first external electrode 21 to the fourth external electrode 24 are electrically connected to the first through-hole conductor TH1 to the fourth through-hole conductor TH4, respectively. Providing the external electrode 20 on the bottom surface (first main surface 11) of the element body 10 enables the multilayer inductor 1 to be properly mounted on a mounting board or the like.

[0042] The first external electrode 21 to the fourth external electrode 24 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).

[0043] The external electrodes 20 may be made of various materials such as Cu and / or Au, for example. The external electrodes 20 may be formed by any method, but may be plated electrodes formed by plating (for example, electroless plating or sputtering), or may have a laminated structure of two or more layers by forming a plated layer of Ni, Sn, or the like on the external electrodes 20 using a plating method after the external electrodes 20 are formed.

[0044] <Method for manufacturing a laminated inductor according to the present disclosure> Next, a method for manufacturing an inductor according to the present disclosure will be described with reference to Fig. 8. The method for manufacturing a laminated inductor according to the present disclosure includes a lamination step and a heat treatment step. As will be described later, the method may optionally include a degreasing step.

[0045] --Laminating Process--First, the magnetic material (magnetic paste) that constitutes the metal magnetic layers ML of the lamination groups G1 to G8 described with reference to FIG. 2 and the conductor paste that constitutes the coil conductor layers CL are prepared.

[0046] As an example of a method for producing a magnetic paste, a metal powder such as an Fe-Si alloy or an Fe-Si-Cr alloy with a volume-based cumulative 50% particle diameter (D50) of 2 μm or more and 20 μm or less is prepared. This metal powder is mixed with a binder such as cellulose or polyvinyl butyral (PVB) and a solvent such as a mixture of terpineol and butyl diglycol acetate (BCA), and then kneaded to produce a magnetic paste.

[0047] When an Fe—Si alloy is used as the metal magnetic material, the Si content is preferably 2.0 at% (atomic percent) or more and 8.0 at% or less. When an Fe—Si—Cr alloy is used as the metal magnetic powder, the Si content is preferably 2.0 at% or more and 8.0 at% or less. Furthermore, when an Fe—Si—Cr alloy is used as the metal magnetic powder, the Cr content is preferably 0.2 at% or more and 6.0 at% or less.

[0048] The conductive paste is prepared, for example, by using Ag as a conductive material and an organic substance (such as an ethyl cellulose resin, an acrylic resin, and / or a polyvinyl butyral resin). In the method for manufacturing a laminated inductor according to the present disclosure, a first conductive paste for an outer conductor layer portion having a low organic substance content and a second conductive paste having a higher organic substance content than the first conductive paste are prepared.

[0049] The above-described magnetic paste and conductor paste are used to prepare and stack the multilayer groups G1 to G8 shown in Fig. 2 by screen printing or the like. Here, when forming the coil conductor layer CL, a first conductor paste with a low organic content is used for the outer conductor layer portion CLo, and a second conductor paste with a high organic content is used for the inner conductor layer portion CLi. Then, after stacking the multilayer groups G1 to G8, a pressure treatment is performed using a press device to form a laminate.

[0050] - Degreasing Process (Optional Process) - A manufacturing process of a preferred laminated inductor may include a degreasing process. The degreasing process is a process for removing binders contained in the magnetic paste and the conductor paste. As an example, degreasing is performed at a temperature of about 300°C or higher and 500°C or lower. This removes the binders contained in the magnetic paste and the conductor paste. In other words, some of the organic matter in the first conductor paste and the second conductor paste may be removed, resulting in voids P.

[0051] Heat Treatment Step After the degreasing step, a heat treatment is performed. The heat treatment temperature is a temperature at which the coil conductor layer is sintered, and may be, for example, about 400°C or higher and 1000°C or lower. The heat treatment step of the present disclosure may be performed in an air atmosphere or a low-oxygen concentration atmosphere. By performing the heat treatment, organic matter in the first conductor paste and the second conductor paste is completely removed, and voids P are generated in the coil conductor layer CL (corresponding to the void generation step).

[0052] Thereafter, the element body may be impregnated with a resin and cured to increase its strength. The resin impregnated into the element body is typically an epoxy resin, but one or more resins selected from the group consisting of phenolic resin, polyester resin, polyimide resin, polyolefin resin, silicone resin, acrylic resin, polyvinyl butyral resin, cellulose resin, alkyd resin, etc. may also be used. Through the above steps, the element body of the laminated inductor of the present disclosure is formed.

[0053] External electrodes electrically connected to the coil conductor layers are then formed on the formed element body. The external electrodes are formed by electrolytic plating at positions where the through-hole conductors are exposed on the mounting surface (first main surface 11) of the element body 10. The plating material may be Cu plating. Other examples include, but are not limited to, Ni-Sn, Ni-Au, Ni-Cu, and / or Cu-Ni-Au. After the external electrodes are formed, the element is cut into individual elements to manufacture the multilayer inductor of this embodiment.

[0054] As described above, the inductor manufacturing method described in this embodiment makes it possible to manufacture a laminated inductor in which the amount of void P in the outer conductor layer portions CLo is smaller than the amount of void P in the inner conductor layer portions CLi. This improves the internal state of the coil conductor layer on the side adjacent to the metal magnetic body, thereby reducing the resistance of the coil conductor layer and improving the skin effect.

[0055] <Another Manufacturing Method of the Laminated Inductor of the Present Disclosure> In the manufacturing method of the laminated inductor described above, one technique for the void generating step may be to degrease the laminate at a degreasing rate of 100° C. / min or more. When the degreasing rate is 100° C. / min or more, the outer conductor layer portions of the coil conductor layers can be degreased more easily than the inner conductor layer portions, and the amount of voids in the outer conductor layer portions can be made smaller than the amount of voids in the inner conductor layer portions.

[0056] 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.

[0057] The present disclosure provides a laminated inductor and a method for manufacturing a laminated inductor as follows. <1> A laminated inductor comprising: an element body including a metal magnetic body having a metal magnetic layer containing metal magnetic particles laminated thereon; and a coil having coil conductor layers laminated in a lamination direction of the metal magnetic layers, wherein the coil conductor layer includes an outer conductor layer portion adjacent to the metal magnetic layer in the lamination direction, and an inner conductor layer portion located inside the outer conductor layer portion and adjacent to the outer conductor layer portion, and wherein the amount of voids in the outer conductor layer portion is smaller than the amount of voids in the inner conductor layer portion. <2> The laminated inductor according to <1>, wherein the thickness of the outer conductor layer portion is 0.1 to 1 times the thickness of the inner conductor layer portion. <3> The laminated inductor according to <1> or <2>, wherein, when the coil conductor layer is viewed in cross section, the area of ​​the voids in the inner conductor layer portion is 1.2 to 3 times the area of ​​the voids in the outer conductor layer portion. <4> The laminated inductor according to any one of <1> to <3>, wherein the coil conductor layer contains Ag. <5> The laminated inductor according to any one of <1> to <4>, wherein the metal magnetic particles contain Fe and Si. <6> The laminated inductor according to any one of <1> to <5>, wherein the inner conductor layer portion is sandwiched between the outer conductor layer portions.

[0058] The laminated inductor of the present disclosure can be used as an electronic component that improves the internal state of the coil conductor layer adjacent to the metal magnetic body, thereby reducing the resistance of the coil conductor layer and improving the skin effect.

[0059] 1 laminated inductor 10 element body 11 first main surface 12 second main surface 13 first end surface 14 second end surface 15 first side surface 16 second side surface 20 external electrode 21 to 24 first to fourth external electrodes C1 to C2 first coil to second coil CL coil conductor layer CD coil conductor G1 to G8 laminated group M metal magnetic material ML metal magnetic layer TH through-hole conductor TH1 to TH4 first to fourth through-hole conductors

Claims

1. A laminated inductor comprising an element body having a metal magnetic body on which metal magnetic layers containing metal magnetic particles are laminated, and a coil in which coil conductor layers are laminated in the lamination direction of the metal magnetic layers, wherein the coil conductor layer comprises an outer conductor layer portion adjacent to the metal magnetic layer in the lamination direction, and an inner conductor layer portion located inside the outer conductor layer portion and adjacent to the outer conductor layer portion, and the amount of voids in the outer conductor layer portion is smaller than the amount of voids in the inner conductor layer portion.

2. The laminated inductor according to claim 1, wherein the thickness of said outer conductor layer portion is 0.1 to 1 times the thickness of said inner conductor layer portion.

3. A laminated inductor according to claim 1 or 2, wherein, when the coil conductor layer is viewed in cross section, the area of ​​the gap in the inner conductor layer portion is 1.2 to 3 times the area of ​​the gap in the outer conductor layer portion.

4. The laminated inductor according to any one of claims 1 to 3, wherein the coil conductor layer contains Ag.

5. A laminated inductor according to any one of claims 1 to 4, wherein the metal magnetic particles contain Fe and Si.

6. A laminated inductor according to any one of claims 1 to 5, wherein the inner conductor layer portion is sandwiched between the outer conductor layer portions.

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