Inductor and method for manufacturing inductor

Abstract

The invention provides an inductor and a manufacturing method of the inductor, and formation abnormity of an external terminal is reduced. This inductor (1) is provided with: a green body (10) which is internally provided with a coil conductor (50) and which contains metal magnetic particles (10a) and a resin; and an external terminal (30) which is provided on the mounting surface (first main surface (11)) of the element (10) and which is electrically connected to the coil conductor (50). The green body (10) has: a first main surface (11) and a second main surface (12) facing each other in the height direction; a first end surface (13) and a second end surface (14) facing each other in the longitudinal direction orthogonal to the height direction; and a first side surface (15) and a second side surface (16) facing each other in the width direction orthogonal to the longitudinal direction and the height direction. The external terminal (30) has a coil conductor connection region (CL) located in an exposed region where the coil conductor (50) is exposed from the element (10) in a plan view viewed from the mounting surface side of the element (10), and an overlapping region (OL) overlapping the element. The average length at which the metal magnetic particles (10a) are in contact with the external terminal (30) is 10% or less of the length of the overlapping region (OL) of the external terminal (30) in a cut surface cut in the height direction of the blank (10) along the length direction of the blank (10) at a position passing through the external terminal (30) and the coil conductor connection region (CL) from the mounting surface side of the blank (10).

Description

TECHNICAL FIELD

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

[0002] An inductor is disclosed in Patent Literature 1, which includes a composite body composed of a composite material of a resin and a metal magnetic powder, an internal electrode provided inside the composite body with an end face exposed from an outer surface of the composite body, and an external terminal electrically connected to the internal electrode. In addition, according to Patent Literature 1, the external terminal is formed by plating (as an example, electroless plating) on the internal electrode. Figure 1 A point at which a planar area of the external terminal is larger than a planar area of the internal electrode can be seen in a planar perspective. That is, a point at which the external terminal contacts the composite body containing the metal magnetic powder can be grasped.

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2022-18910

[0004] An external terminal of an inductor is electrically connected to an electrode of a mounting substrate on which the inductor is mounted. When the inductor is mounted on the mounting substrate, it is sometimes desired to increase a planar area of the external terminal from the viewpoint of alignment with the mounting substrate. If the planar area of the external terminal is increased, the composite body (a blank of the inductor) disposed around the internal electrode contacts the external terminal.

[0005] Here, in a case where the external terminal is formed by plating (as an example, electroless plating), a plating formation mechanism for the internal electrode is different from a plating formation mechanism for the composite body containing the metal magnetic powder. That is, if the external terminal is formed by plating, plating growth caused by the metal magnetic powder contained in the composite body occurs, abnormal formation of the external terminal occurs, and thus there is a concern that the yield of the inductor decreases. SUMMARY

[0006] The present disclosure has been achieved in view of the problem. That is, a main object of the present disclosure is to provide an inductor and a manufacturing method of an inductor that reduce abnormal formation of an external terminal.

[0007] The inductor of the present disclosure includes a core having a coil conductor inside, containing metal magnetic particles and resin; and an external terminal provided on a mounting surface of the core and electrically connected to the coil conductor. The core has a first main surface and a second main surface facing each other in a height direction, a first end surface and a second end surface facing each other in a length direction orthogonal to the height direction, and a first side surface and a second side surface facing each other in a width direction orthogonal to the length direction and the height direction. The external terminal has a coil conductor connection region on a protruding region of the coil conductor protruding from the core in a planar perspective view from the mounting surface side of the core, and an overlapping region overlapping the core. In a cut surface cut in the height direction of the core along the length direction of the core at a position passing through the external terminal and the coil conductor connection region from the mounting surface side of the core, an average length of the metal magnetic particles in contact with the external terminal is 10% or less of a length of the overlapping region of the external terminal.

[0008] In addition, the inductor of the present disclosure includes a core having a coil conductor inside, containing metal magnetic particles and resin; and an external terminal provided on a mounting surface of the core and electrically connected to the coil conductor. In a planar perspective view from the mounting surface side of the core, the external terminal is disposed inside a protruding region of the coil conductor protruding from the core.

[0009] The manufacturing method of the inductor of the present disclosure includes a core forming step of forming a core having a coil conductor inside, containing metal magnetic particles and resin; a protruding step of protruding an external terminal connection region of the coil conductor from the core; a degranulation step of degranulating the metal magnetic particles in a mounting surface of the core; and an external terminal forming step of forming an external terminal at a degranulation site where the metal magnetic particles are degranulated by the degranulation step and at a site of the external terminal connection region of the coil conductor protruding from the core by the protruding step.

[0010] In addition, the manufacturing method of the inductor of the present disclosure includes a core forming step of forming a core having a coil conductor inside, containing metal magnetic particles and resin; a protruding step of protruding an external terminal connection region of the coil conductor from the core; and an external terminal forming step of forming an external terminal inside a protruding region of the external terminal connection region of the coil conductor protruding from the core.

[0011] According to the present disclosure, it is possible to provide an inductor and a manufacturing method of an inductor, which reduce formation abnormalities of external terminals. More specifically, in the inductor of the present disclosure, in a cut surface cut in a height direction of a blank at a position passing through an external terminal and a coil conductor connection region from a mounting surface side of the blank along a length direction of the blank, an average length of a metal magnetic particle in contact with the external terminal is 10% or less with respect to a length of an overlapping region of the external terminal, and thus plating growth caused by the metal magnetic particle can be reduced. Therefore, it is possible to reduce formation abnormalities of the external terminal.

[0012] In addition, other inductors of the present disclosure are configured with an external terminal at a position inside a region in which a coil conductor is exposed from a blank, in a plan view perspective viewed from a mounting surface side of the blank, and thus it is possible to prevent a metal magnetic particle from being in contact with the external terminal, and it is possible to reduce formation abnormalities of the external terminal. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a perspective view of an inductor of the present disclosure.

[0014] Figure 2 is an exploded perspective view of an inductor of a first embodiment.

[0015] Figure 3 is a cross-sectional view of an arrow direction of a III-III line of Figure 2

[0016] Figure 4 is a main part enlarged cross-sectional view of Figure 3

[0017] Figure 5 is an exploded perspective view of an inductor of a second embodiment.

[0018] Figure 6 is a cross-sectional view of an arrow direction of a VI-VI line of Figure 5

[0019] Figure 7 is a main part enlarged cross-sectional view of Figure 6

[0020] Figure 8 is a main part enlarged cross-sectional view of an inductor of a modification of the second embodiment.

[0021] Figure 9 is a cross-sectional view of an inductor of another embodiment.

[0022] Figure 10 is a flowchart showing a manufacturing method of an inductor of the present disclosure.

[0023] Figure 11 is an elemental analysis photograph explaining an elemental analysis result.​​​​

[0024] Figure 12 is a cross-sectional view that explains the state of deagglomeration of the metal magnetic particles.

[0025] Figure 13 is a cross-sectional view that explains the state of plating formation.

[0026] Figure 14 is a cross-sectional photograph that explains the state of contact of the metal magnetic particles with the external terminal.

[0027] Figure 15 is a perspective view of another embodiment of the inductor of the present disclosure.

[0028] Figure 16 is an exploded perspective view of another embodiment of the inductor of the present disclosure.

[0029] Figure 17 is a cross-sectional view of the arrow direction of XVII-XVII line of Figure 16

[0030] Figure 18 is a perspective view of another other embodiment of the inductor of the present disclosure.

[0031] Figure 19 is an exploded perspective view of another other embodiment of the inductor of the present disclosure. DETAILED DESCRIPTION

[0032] Hereinafter, the inductor of the present disclosure will be explained. Furthermore, the present disclosure is not limited to the following structure, and can be appropriately changed within the range not departing from the gist of the present disclosure. In addition, the structure obtained by combining a plurality of each of the preferred structures described below is also the present disclosure.

[0033] The inductor of the present disclosure is used, for example, for a DC-DC converter. In addition, the inductor of the present disclosure can also be applied to uses other than the DC-DC converter.

[0034] In the present specification, the terms indicating the relationship between elements (for example, "parallel", "orthogonal", and the like) and the terms indicating the shape of the element do not only mean the strict manner like the literal, but also mean the substantially equivalent range, for example, the range including a difference of several % or so. Furthermore, in the present specification, the direction in which the magnetic layer and the coil conductor layer constituting the green sheet are stacked is set as the "stacking direction".

[0035] ​In addition, in the description of the present specification, the mention of directions or orientations and the like is for the purpose of facilitating the explanation, and is not intended to limit the scope of the present disclosure, unless specifically stated otherwise. For example, relative terms such as "outer (or outside, exterior, or periphery)", "inner (or inside, interior, or inner periphery)", and the like, and their derivative terms and the like, are to be understood as the directions as recited or as illustrated. That is, unless specifically and explicitly stated otherwise, the present disclosure is not intended to be limited to only a specific direction, orientation, manner, and the like. In addition, terms such as "provided", "disposed", "connected", "contacted", "bonded", and the like, and their derivative terms are also the same, and unless specifically and explicitly stated otherwise, are not limited to a direct manner, but can also be a manner in which other elements such as an interposed element are interposed.

[0036] The drawings shown below are schematic drawings, and the scale of the size, the aspect ratio, and the like can sometimes be different from those of the actual product.

[0037] <Inductor of First Embodiment>

[0038] While referring to Figures 1-4 , a first embodiment of an inductor of the present disclosure will be described. Figure 1 is a perspective view of an inductor of the present disclosure, Figure 2 is an exploded perspective view of the inductor of the first embodiment, Figure 3 is Figure 2 is a cross-sectional view in the arrow direction of the III-III line of Figure 4 is Figure 3 is a main part enlarged cross-sectional view of . It should be noted that the shapes and the arrangement and the like of the inductor and each constituent element are not limited to the examples illustrated.

[0039] The inductor 1 of the present disclosure is provided with: a blank 10 provided with a coil conductor 50 inside, containing a metal magnetic particle 10a and a resin; an insulating layer 70 provided on a mounting surface (first main surface 11) of the blank 10, provided on the mounting surface of the blank 10 provided with the coil conductor 50 inside, in a region where an external terminal 30 is not provided; and the external terminal 30 electrically connected to the coil conductor 50.

[0040] In the present embodiment, the blank 10 is provided with a first coil 21 and a second coil 22, and the second coil 22 is located on the upper side in the height direction T than the first coil 21. In addition, the coil provided inside the blank 10 is not limited to the above-described manner, and a manner of being provided with one coil or a manner of being provided with two or more coils can also be employed. For example, as Figure 9 indicated, a manner of being provided with four coils in the blank 10 can also be employed. In addition, the laminated groups G4 and G5 (refer to Figure 2) The first coil conductor 51 is wound in a spiral shape via a via conductor (not shown) to constitute the first coil 21 by being stacked multiple times. The first coil conductor 51 can be constituted by stacking the later-described stacked groups G2 and G3 (refer to Figure 2 ) The second coil conductor 52 is wound in a spiral shape via a via conductor (not shown) to constitute the second coil 22 by being stacked multiple times. Hereinafter, each constituent element will be described in detail.

[0041] Green Body

[0042] The green body 10 has, for example, a rectangular parallelepiped shape or a substantially rectangular parallelepiped shape. The green body 10 can also have a rounded corner at a corner portion and a rounded edge at an edge portion. The corner portion is a portion where three faces of the green body 10 intersect, and the edge portion is a portion where two faces of the green body 10 intersect.

[0043] In Figure 1 , the length direction, the width direction, and the height direction in the inductor 1 and the green body 10 are denoted as the L direction, the W direction, and the T direction, respectively. The length direction L, the width direction W, and the height direction T are orthogonal to each other. The mounting surface of the inductor 1 is, for example, a surface (LW surface) parallel to the length direction L and the width direction W.

[0044] Figure 1 The green body 10 illustrated in the drawing has a first main surface 11 and a second main surface 12 that are opposite in the height direction T, a first end surface 13 and a second end surface 14 that are opposite in the length direction L orthogonal to the height direction T, and a first side surface 15 and a second side surface 16 that are opposite in the width direction W orthogonal to the length direction L and the height direction T. In Figure 1 In the example illustrated in the drawing, the first main surface 11 of the green body 10 corresponds to the mounting surface (bottom surface) of the green body 10. In addition, the second main surface 12 can also be the mounting surface of the green body 10.

[0045] The green body 10 includes a magnetic layer S and a coil conductor 50 (refer to Figure 2 ). In addition, the green body 10 can have a stacked structure. Specifically, the green body 10 can include a plurality of magnetic layers S and coil conductors 50 in the stacking direction (for example, the height direction T). In the present embodiment, as Figure 2 illustrated in the drawing, a stacked group G1 to G7 including at least one magnetic layer S and a coil conductor 50 (or only a magnetic layer S) is stacked to constitute. In addition, the boundary of each layer of the stacked structure possessed by the green body 10 disappears. In addition, the same pattern can be stacked multiple times to constitute each stacked group layer.

[0046] The stacked group G1 has a magnetic layer S, and constitutes the second main surface 12 of the green body 10.

[0047] The stacked group G2 is provided with the magnetic layer S and the second coil conductor 52 that constitutes a part of the second coil 22. One winding of the second coil 22 is constituted by the second coil conductor 52 of the stacked group G2. More specifically, the second coil conductor 52 is arranged along the substantially outer periphery of the magnetic layer S. In addition, one of the end portions of the second coil conductor 52 is provided with a conductor layer (or a via conductor) (not shown) for connection with the second coil conductor 52 of the stacked group G3, and the other of the end portions of the second coil conductor 52 is provided with a fourth coil conductor connection portion (not shown) for electrical connection with the fourth external terminal 34.

[0048] The stacked group G3 is provided with the magnetic layer S and the second coil conductor 52 that constitutes a part of the second coil 22. The other winding of the second coil 22 is constituted by the second coil conductor 52 of the stacked group G3. One of the end portions of the second coil conductor 52 is connected with the second coil conductor 52 of the stacked group G2, and the other of the end portions of the second coil conductor 52 is provided with a third coil conductor connection portion (not shown) for electrical connection with the third external terminal 33. In addition, a fourth coil conductor connection portion 54v is provided in the corner of the magnetic layer S that is away from the second coil conductor 52 in plan view, for electrical connection with the fourth coil conductor connection portion (not shown) of the stacked group G2.

[0049] The stacked group G4 is provided with the magnetic layer S and the first coil conductor 51 that constitutes a part of the first coil 21. One winding of the first coil 21 is constituted by the first coil conductor 51 of the stacked group G4. One of the end portions of the first coil conductor 51 is provided with a conductor layer (or a via conductor) (not shown) for connection with the first coil conductor 51 of the stacked group G5, and the other of the end portions of the first coil conductor 51 is provided with a second coil conductor connection portion (not shown) for electrical connection with the second external terminal 32. In addition, a fourth coil conductor connection portion 54v is provided in each of the corners of the magnetic layer S that is away from the first coil conductor 51 in plan view, for electrical connection with the fourth coil conductor connection portion of the stacked group G3, and a third coil conductor connection portion 53v is provided for electrical connection with the third coil conductor connection portion of the stacked group G3.

[0050] The stacked group G5 is provided with the magnetic layer S and the first coil conductor 51 that constitutes a part of the first coil 21. The other windings of the first coil 21 are constituted by the first coil conductor 51 of the stacked group G5. One of the end portions of the first coil conductor 51 is connected to the first coil conductor 51 of the stacked group G4, and the other of the end portions of the first coil conductor 51 is provided with a first coil conductor connection portion (not shown) for electrical connection with the first external terminal 31. Further, in the magnetic layer S, fourth coil conductor connection portions 54v are provided at the corners away from the first coil conductor 51 in plan view to be electrically connected to the fourth coil conductor connection portions 54v of the stacked group G4, third coil conductor connection portions 53v are provided to be electrically connected to the third coil conductor connection portions 53v of the stacked group G4, and second coil conductor connection portions 52v are provided to be electrically connected to the second coil conductor connection portions 52v of the stacked group G4.

[0051] The stacked group G6 is provided with the magnetic layer S and the first coil conductor connection portion 51v, the second coil conductor connection portion 52v, the third coil conductor connection portion 53v, and the fourth coil conductor connection portion 54v are provided at the corners.

[0052] The stacked group G7 is provided with the magnetic layer S and the first coil conductor connection portion 51v, the second coil conductor connection portion 52v, the third coil conductor connection portion 53v, and the fourth coil conductor connection portion 54v are provided at the corners with larger planar areas than the first to fourth coil conductor connection portions of the stacked group G6. By making the planar areas of the first to fourth coil conductor connection portions of the stacked group G7 larger than those of the stacked group G6, alignment of the coil conductor connection portions with each other can be easily performed.

[0053] If the blank 10 has the stacked structure with the stacked groups G1 to G7 as above, the degree of freedom of design of the inductor 1 becomes higher. For example, in the case of manufacturing the inductor 1 provided with the first external terminal 31, the second external terminal 32, the third external terminal 33, and the fourth external terminal 34 on the bottom surface (the first main surface 11) of the blank 10, it is easy to lead out the first coil 21 and the second coil 22 to the bottom surface side. Further, the stacked structure with the stacked groups G1 to G7 described above can be formed by sequentially printing (for example, screen printing or the like) the material constituting the magnetic layer S, the material constituting the coil conductor 50, and the material constituting the coil conductor connection portion 50v from the second main surface 12 side or from the first main surface 11 side of the blank 10. In this case, each of the stacked groups G1 to G7 can also be repeatedly printed until the magnetic layer S, the coil conductor 50, and the coil conductor connection portion 50v become the desired thickness.

[0054] The magnetic layer S contains metal magnetic particles 10a (refer to Figure 4). The metal magnetic particle 10a can contain Fe and / or Si. More specifically, it can be a Fe particle or a Fe alloy particle. As the Fe alloy, it can be a Fe-Si-based alloy, a Fe-Si-Cr-based alloy, a Fe-Si-Al-based alloy, a Fe-Si-B-P-Cu-C-based alloy, a Fe-Si-B-Nb-Cu-based alloy, or the like. In addition, in the metal magnetic particle 10a, impurities such as Cr, Mn, Cu, Ni, P, S, or Co, which are not desired in terms of manufacturing, can be contained. In addition, regarding the metal magnetic particle 10a, detailed description is made in the description of the manufacturing method, but it can also be contained in the magnetic paste. Therefore, in the metal magnetic particle, an element (for example, Cr, Al, Li, Zn) that is more easily oxidized than Fe can also be contained when the magnetic paste is produced.

[0055] The surface of the metal magnetic particle 10a composed of the metal magnetic material described above can be covered with an insulating coating film (not shown). If the surface of the metal magnetic particle is covered with the insulating coating film, the insulating property between the metal magnetic particles can be improved. As a method of forming the insulating coating film on the surface of the metal magnetic particle, a sol-gel method, a mechanochemical method, or the like can be used. The material constituting the insulating coating film can be an oxide of P, Si, or the like. In addition, the insulating coating film can also be an oxide film formed by oxidizing the surface of the metal magnetic particle. The thickness of the insulating coating film is preferably 1 nm or more and 50 nm or less, more preferably 1 nm or more and 30 nm or less, and further preferably 1 nm or more and 20 nm or less. For example, the cross section of a test piece obtained by grinding the inductor can be photographed with a scanning electron microscope (SEM), and the thickness of the insulating coating film covering the surface of the metal magnetic particle can be determined from the obtained SEM photograph.

[0056] The average particle diameter of the metal magnetic particle 10a in the magnetic layer S is preferably 1 μm or more and 30 μm or less, more preferably 1 μm or more and 20 μm or less, and further preferably 1 μm or more and 10 μm or less. The average particle diameter of the metal magnetic particle 10a in the magnetic layer can be determined in accordance with the following procedure. A test piece is obtained by cutting the inductor. Specifically, a test piece is obtained by cutting through the center portion of the blank so as to be orthogonal to the mounting surface and the end surface of the blank. For the obtained cross section, the regions (for example, 130 μm x 100 μm) of a plurality of sites (for example, five sites) are photographed with an SEM, the obtained SEM images are analyzed using image analysis software (for example, image analysis software WinROOF2021 (manufactured by San-ei Denki Co., Ltd.)), and the equivalent circle diameter of the metal magnetic particle is calculated. The average value of the obtained equivalent circle diameters is set as the average particle diameter of the metal magnetic particle.

[0057] When the green body 10 is formed, heat treatment is performed. In this case, the metal magnetic particles 10a included in the green body 10 have an oxide film on the surface. The oxide film is derived from the metal magnetic particles 10a and is formed by the heat treatment. In the green body 10, the adjoining metal magnetic particles 10a are joined to each other via the oxide film.

[0058] The green body 10 can also include a non-magnetic layer between the first coil 21 and the second coil 22. By providing the non-magnetic layer between the first coil 21 and the second coil 22, it is possible to improve the insulation between the first coil 21 and the second coil 22 and prevent short-circuiting therebetween.

[0059] The non-magnetic layer can include a glass-ceramic material and a non-magnetic ferrite material or the like as the non-magnetic material. The non-magnetic layer can include a non-magnetic ferrite material as the non-magnetic material. As the non-magnetic ferrite material, a non-magnetic ferrite material having a composition in which Fe is converted into Fe2O3 to be 40 mol% or more and 49.5 mol% or less based on the entire non-magnetic layer, Cu is converted into CuO to be 6 mol% or more and 12 mol% or less based on the entire non-magnetic layer, and the remainder is ZnO can be used. As necessary, Mn3O4, Co3O4, SnO2, Bi2O3, SiO2, or the like can be contained as an additive in the non-magnetic material, and a trace amount of unavoidable impurities can also be contained. The non-magnetic layer preferably contains a Zn-Cu-based ferrite.

[0060] The thickness of the non-magnetic layer can be measured according to the following procedure. The test piece of the inductor is vertically erected, and the periphery of the test piece is fixed with a resin. At this time, the LT surface is exposed. Polishing is ended at a depth of about 1 / 2 of the W direction of the test piece using a polisher, and a cross section parallel to the LT surface is exposed. In order to remove the sagging of the internal conductor due to polishing, the polished surface is processed by ion milling (manufactured by Hitachi High-Tech Corporation, ion milling device IM4000) after the polishing is ended. The approximately central portion of the non-magnetic layer in the test piece after polishing is photographed using an SEM, and the thickness of the approximately central portion of the non-magnetic layer is measured from the obtained SEM photograph, which is defined as the thickness of the non-magnetic layer.

[0061] The green body 10 can also include a non-magnetic portion between the first coil conductors 51 constituting the first coil 21 or between the second coil conductors 52 constituting the second coil 22. In this case, the non-magnetic portion is provided at least one of the adjoining coil conductors among the first coil conductors 51 and the second coil conductors 52. By providing the non-magnetic portion between the adjoining coil conductors, it is possible to prevent the magnetic flux from leaking between the coil conductors and the inductance value from decreasing.

[0062] The non-magnetic layer and the non-magnetic portion can have the same composition. For example, the non-magnetic layer and the non-magnetic portion can be composed of a Zn-Cu-based ferrite.

[0063] The first coil 21 and the second coil 22 are provided inside the green sheet 10. The first coil 21 and the second coil 22 can be 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. In addition, only two coils including the first coil 21 and the second coil 22 can be provided inside the green sheet 10, or three or more coils including the first coil 21 and the second coil 22 can be provided.

[0064] - First Coil -

[0065] The first coil 21 includes a plurality of first coil conductors 51 in the stacking direction (for example, the height direction T). Adjacent first coil conductors 51 are connected to each other via a via conductor. In addition, the first coil 21 can have a winding number of 1.75 by including first coil conductors 51 formed in two different stacking groups in the stacking direction. In addition, the winding number is not limited to 1.75, and the winding number can be, for example, 2 or more by stacking the first coil conductors 51 in the stacking direction.

[0066] The thicknesses of the first coil conductors 51 can be the same, respectively. In addition, the thicknesses of the first coil conductors 51 can be the same as the thicknesses of the second coil conductors 52 described later.

[0067] As an example of the material of the first coil conductors 51, a metal conductor such as Ag, Cu, and / or Pd can be used. The first coil conductors 51 can be formed, for example, by printing a conductive paste on the magnetic layer S described above.

[0068] - Second Coil -

[0069] The second coil 22 includes a plurality of second coil conductors 52 in the stacking direction (for example, the height direction T). Adjacent second coil conductors 52 are connected to each other via a via conductor. In addition, the second coil 22 can have a winding number of 1.75 by including second coil conductors 52 formed in two different stacking groups in the stacking direction. In addition, the winding number is not limited to 1.75 in the illustrated example, and the winding number can be, for example, 2 or more by stacking the first coil conductors 52 in the stacking direction. In addition, the number of layers of the second coil conductors 52 can be the same as or different from the number of layers of the first coil conductors 51.

[0070] The thicknesses of the second coil conductors 52 can be the same, respectively. In addition, the thicknesses of the second coil conductors 52 can be the same as the thicknesses of the first coil conductors 51.

[0071] As an example of the material of the second coil conductor 52, a metal conductor such as Ag, Cu, and / or Pd can be used. Alternatively, the same kind of material as the first coil conductor 51 can be used, or a different kind of material can be used. The second coil conductor 52 can be formed by, for example, printing a conductive paste in a through-hole formed in the magnetic layer S described above.

[0072] - Coil conductor connection part -

[0073] The coil conductor 50 includes a coil conductor connection part 50v. The coil conductor connection part 50v includes a first coil conductor connection part 51v, a second coil conductor connection part 52v, a third coil conductor connection part 53v, and a fourth coil conductor connection part 54v. The first coil conductor connection part 51v, the second coil conductor connection part 52v, the third coil conductor connection part 53v, and the fourth coil conductor connection part 54v are provided inside the green sheet 10. Moreover, the first coil conductor connection part 51v, the second coil conductor connection part 52v, the third coil conductor connection part 53v, and the fourth coil conductor connection part 54v are exposed from the mounting surface (the first main surface 11) of the green sheet 10.

[0074] As an example of the material of the coil conductor connection part 50v, a metal conductor such as Ag, Cu, and / or Pd can be used. Alternatively, the same kind of material as the first coil conductor 51 and / or the second coil conductor 52 can be used, or a different kind of material can be used. The coil conductor connection part 50v can be formed by, for example, forming a through-hole in the magnetic layer S described above, and printing a conductive paste in the through-hole.

[0075] The first coil conductor connection part 51v connects the end portion of the first coil conductor 51 of the first coil 21, which is closest to the bottom surface (the first main surface 11) of the green sheet 10, and the first external terminal 31. The first coil conductor connection part 51v can extend in the stacking direction (for example, the height direction T). The first coil conductor connection part 51v can also have a stacked structure.

[0076] The second coil conductor connection part 52v connects the other end portion of the first coil 21 and the second external terminal 32. The second coil conductor connection part 52v can extend in the stacking direction (for example, the height direction T). The second coil conductor connection part 52v can also have a stacked structure.

[0077] The third coil conductor connection part 53v connects the end portion of the second coil conductor 52 of the second coil 22, which is closest to the bottom surface (the first main surface 11) of the green sheet 10, and the third external terminal 33. The third coil conductor connection part 53v can extend in the stacking direction (for example, the height direction T). The third coil conductor connection part 53v can also have a stacked structure.

[0078] The fourth coil conductor connection 54v connects the other end of the second coil 22 to the fourth external terminal 34. The fourth coil conductor connection 54v may extend along the stacking direction (e.g., the height direction T). The fourth coil conductor connection 54v may also have a stacked structure.

[0079] Here, as a preferred configuration of the coil conductor connection portion 50v, the second coil conductor connection portion 52v and the third coil conductor connection portion 53v, which are electrically connected to the output electrode of the inductor 1, are arranged along one side of the outer edge constituting the blank body 10. In other words, the second coil conductor connection portion 52v and the third coil conductor connection portion 53v are not arranged along the diagonal of the blank body 10 when viewed from the stacking direction. By arranging the coil conductor connection portion 50v in this way, the output electrode and the input electrode can be aligned in the same direction.

[0080] -External terminal-

[0081] like Figure 2 As shown, the external terminal 30 includes a first external terminal 31, a second external terminal 32, a third external terminal 33, and a fourth external terminal 34. The first external terminal 31 and the second external terminal 32 are disposed on the first main surface 11 of the blank 10 and are electrically connected to the first coil 21. The third external terminal 33 and the fourth external terminal 34 are disposed on the first main surface 11 of the blank 10 and are electrically connected to the second coil 22. In the inductor 1, the first main surface 11 of the blank 10 can be used as the mounting surface.

[0082] The first external terminal 31 functions as an input electrode for the first coil 21. The first external terminal 31 may be provided only on the first main surface 11 of the blank 10, or it may be provided across at least one of the first main surface 11, the first end surface 13, and the second side surface 16 of the blank 10.

[0083] The second external terminal 32 functions as an output electrode for the first coil 21. The second external terminal 32 may be provided only on the first main surface 11 of the blank 10, or it may be provided across at least one of the first main surface 11, the second end surface 14, and the second side surface 16 of the blank 10.

[0084] The third external terminal 33 functions as an output electrode for the second coil 22. The third external terminal 33 may be provided only on the first main surface 11 of the blank 10, or it may be provided across at least one of the first main surface 11, the second end surface 14, and the first side surface 15 of the blank 10.

[0085] The fourth external terminal 34 functions as an input electrode for the second coil 22. The fourth external terminal 34 can be provided only on the first main surface 11 of the blank 10, but can be provided across at least one of the first main surface 11, the first end surface 13, and the first side surface 15 of the blank 10.

[0086] The external terminal 30 has a coil conductor connection region CL on a region where the coil conductor 50 is exposed from the blank 10 in a plan view from the mounting surface side of the blank 10 (a region where the coil conductor connection portion 50v is exposed), and an overlapping region OL that overlaps the blank 10. In other words, the planar area of the external terminal 30 is larger than the planar area of the coil conductor connection portion 50v in a plan view from the mounting surface side of the blank 10. By making the planar area of the external terminal 30 relatively large, the alignment of the electrode of the mounting substrate and the external terminal 30 of the inductor 1 can be easily performed when the inductor 1 is mounted on the mounting substrate or the like.

[0087] As an example, the external terminal 30 can be formed of various materials such as Cu, Ni, or the like. In addition, the external terminal 30 can be formed of one layer, or can be a laminated structure of two or more layers. The external terminal 30 can be formed by any method, but as an example, can be formed by plating (e.g., electroless plating). In the case where the external terminal 30 is formed by plating, the plating formation mechanism for the coil conductor connection portion 50v is different from the plating formation mechanism for the blank 10 containing the metal magnetic particles 10a. Therefore, in the inductor 1 according to the present embodiment, in a cross section that is cut along the length direction of the blank 10 in the height direction of the blank 10 at a position where the external terminal 30 passes through the blank 10 from the mounting surface (the first main surface 11) side of the blank 10, the average length of the metal magnetic particles 10a that are in contact with the external terminal 30 is 10% or less, preferably 8% or less, further preferably 4% or less, and further preferably 0% (see FIG. 6) of the length of the overlapping region OL of the external terminal 30. Note that the calculation method of the "average length of the metal magnetic particles in contact with the external terminal" described in the present specification is described in detail in the Examples described later. Figure 4

[0088] ​Here, the specific plating formation mechanism is described in detail. As an example, in a case where the metal magnetic particle 10a is set to Fe, the coil conductor connecting portion 50v is set to Ag, and the external terminal 30 is set to Cu, the ionization tendency of the metal magnetic particle (Fe) is greater than that of the coil conductor connecting portion (Ag), and the reaction of plating growth preferentially starts on the side of the metal magnetic particle with the greater ionization tendency. Therefore, the conventional "inductor in which the external terminal has a larger planar area than the coil conductor connecting portion in a planar perspective view observed from the mounting surface side of the blank 10, and the external terminal contacts the blank containing the metal magnetic powder" causes plating growth due to the metal magnetic particle, and thus causes formation abnormalities of the external terminal.

[0089] However, according to the inductor 1 related to the present embodiment, the average length of the metal magnetic particle 10a contacting the external terminal 30 is 10% or less with respect to the length of the overlapping region OL (see FIG. 6), and thus plating growth due to the metal magnetic particle 10a can be reduced. Therefore, formation abnormalities of the external terminal 30 can be reduced. Figure 4

[0090] As an example of a method in which the average length of the metal magnetic particle 10a contacting the external terminal 30 is 10% or less with respect to the length of the overlapping region OL, deagglomeration of the metal magnetic particle 10a can be achieved on the mounting surface (first main surface 11) of the blank 10. According to such a structure, the metal magnetic particle 10a is removed from the mounting surface of the blank 10, and thus the proportion of the metal magnetic particle 10a in the mounting surface can be further reduced, and the metal magnetic particle 10a contacting the external terminal 30 can be further reduced.

[0091] In addition, the deagglomeration of the metal magnetic particle 10a is not limited to the mounting surface of the blank 10, and the metal magnetic particle 10a can be deagglomerated on a surface other than the mounting surface of the blank 10 (for example, the second main surface 12, the first end surface 13, the second end surface 14, the first side surface 15, and / or the second side surface 16). According to such a structure, the metal magnetic particle 10a around the blank 10 is removed, and thus the formation of plating growth due to the metal magnetic particle 10a can be reduced.

[0092] Regarding the deagglomeration of the metal magnetic particle 10a, the surface roughness of the mounting surface (first main surface 11) of the blank 10 is greater than the surface roughness of the surface on the side opposite to the mounting surface of the blank 10 (second main surface 12). In the present specification, the surface roughness can be measured by the following method.

[0093] (1) An imaginary line extending along the external terminal and the coil conductor connecting region passing through the mounting surface of the blank 10 and in the length direction L of the blank is prepared, and the height direction T (see FIG. 6) of the blank 10 is measured from the mounting surface side. Figure 1 ​) parallel cut surfaces. The cut surfaces are along the width direction W (refer to Figure 1 ) three places are made.

[0094] (2) Among the cut surfaces, the central and both ends of the external terminal, which are longer in distance from the coil conductor connection region to the front end, in the portion of the first main surface of the compact 10, which extends outward on both sides of the coil conductor connection region of the external terminal 30 and contacts the compact 10, and the second main surface 12 of the compact 10, which are three places corresponding to the photographed places, are photographed at 5000 times magnification using an SEM (manufacturer name: JEOL Ltd., Schottky field emission scanning electron microscope, model number: JSM-7900F) and an EDX (manufacturer name: JEOL Ltd., Schottky field emission scanning electron microscope, model number: JSM-7900F).

[0095] (3) In the respective photographed fields of view, the composition (for example, Fe) of the metal magnetic particles 10a contained in the compact 10, and the position of the composition (for example, Cu) of the external terminal 30 are confirmed using the EDX, respectively, whereby the positional relationship of the metal magnetic particles in the SEM can be confirmed.

[0096] Next, the image analysis software "WinRooF" (manufactured by Mitsui Bussan Corporation) is read into the SEM image, and the outer edge of the metal magnetic particles on the compact surface side in the SEM image is determined based on the composition image (for example, Fe composition image) of the metal magnetic particles by EDX.

[0097] Furthermore, a tangent line is drawn for the outer edge of the metal magnetic particle on the compact surface side that is the first among the outer edges of the metal magnetic particles within the field of view, and the outer edge of the metal magnetic particle on the compact surface side that is the second among the outer edges of the metal magnetic particles, and the distance of the outer edge of the metal magnetic particle on the compact interior side that is the first among the outer edges of the metal magnetic particles from the tangent line is measured. By performing this measurement on the first main surface 11 and the second main surface 12 of the compact 10, the surface roughness of the first main surface 11 and the surface roughness of the second main surface 12 (maximum unevenness) can be measured.

[0098] As a preferable mode of the external terminal 30, the external terminal 30 can enter the recessed portion after the metal magnetic particles 10a are degranulated in the mounting surface (first main surface 11) of the compact 10. According to such a structure, an anchoring effect is brought about by the external terminal 30 entering the recessed portion after the metal magnetic particles 10a are degranulated, and thus the adhesion of the compact 10 and the external terminal 30 can be improved.

[0099] - Insulating layer -

[0100] The insulating layer 70 covers the surface of the mounting surface (first main surface 11) of the green sheet 10 except for the external terminal 30. Specifically, it is a layer laminated on the first main surface 11 of the green sheet 10 (refer to Figures 1-4 ). As an example, a photoresist is cited. In this way, in the inductor 1 of the present embodiment, by providing the insulating layer 70, it is possible to prevent short-circuiting between the inductor 1 and the mounting substrate on which the inductor 1 is mounted.

[0101] In addition, as a preferable mode of the insulating layer 70, the insulating layer 70 can also enter the recesses (refer to Figure 4 ) after the metal magnetic particles 10a are degranulated in the mounting surface (first main surface 11) of the green sheet 10. According to such a structure, by the insulating layer 70 entering the recesses after the metal magnetic particles 10a are degranulated, an anchoring effect is brought about, and thus it is possible to improve the adhesion of the green sheet 10 and the insulating layer 70.

[0102] <Inductor of Second Embodiment>

[0103] Next, the inductor of the second embodiment will be described with reference to Figures 5-8 . Figure 5 is an exploded perspective view of the inductor of the second embodiment, Figure 6 is a cross-sectional view in the arrow direction of the VI-VI line of Figure 5 , Figure 7 is a main part enlarged cross-sectional view of Figure 6 , Figure 8 is a main part enlarged cross-sectional view of the inductor of a modification of the second embodiment. The structure of the inductor of the second embodiment related to the external terminal is different from that of the inductor of the first embodiment described above. In the following description, the points different from the inductor described in the above-described embodiment will be described as the center.

[0104] The inductor 1 of the present embodiment internally has the coil conductor 50, and has: a green sheet 10 containing metal magnetic particles 10a; a coil conductor connection portion 50v electrically connected to the coil conductor 50 and exposed from the green sheet 10; and an external terminal 30 provided to the mounting surface (first main surface 11) of the green sheet 10 and electrically connected to the coil conductor connection portion 50v. Moreover, in a planar perspective view from the mounting surface side of the green sheet 10, the external terminal 30 is disposed inside the exposed region E in which the coil conductor connection portion 50v is exposed from the green sheet 10 (refer to Figure 6 and Figure 7 ).

[0105] More specifically, the inductor 1 of this embodiment differs from that of the first embodiment in that, in a top view taken from the mounting surface side of the blank 10, the planar area of ​​the external terminal 30 is smaller than the planar area of ​​the coil conductor connection portion 50v. In other words, in a top view taken from the mounting surface side of the blank 10, there is no overlapping area where the external terminal 30 overlaps with the blank 10. However, in terms of having the technical concept of "not generating plating growth caused by the metallic magnetic particles contained in the blank," the inductor of the first embodiment and the inductor of the second embodiment share the same technical concept.

[0106] That is, in the top view of the inductor 1 of the second embodiment, when viewed from the mounting surface side of the blank 10, an external terminal 30 is arranged inside the exposed area E where the coil conductor connection portion 50v is exposed from the blank 10, so that the blank 10 does not come into contact with the external terminal 30. Therefore, even if the external terminal 30 is formed by plating, the abnormality of the formation of the external terminal 30 can be reduced.

[0107] In a preferred embodiment of the inductor, the depth of the recess after threshing the metallic magnetic particles 10a can be greater than or equal to twice the maximum particle size of the metallic magnetic particles 10a. Furthermore, the method for determining the maximum particle size is the method described in <Inductor of the First Embodiment>. Specifically, a sample cross-section is obtained by cutting through the center of the blank and orthogonally to the mounting surface and end face of the blank. For the obtained cross-section, multiple areas (e.g., five areas) (e.g., 130 μm × 100 μm) are photographed using SEM, and the obtained SEM images are analyzed using image analysis software (e.g., WinROOF2021 image analysis software (manufactured by Mitani Corporation)) to determine the equivalent circle diameter of the metallic magnetic particles. The maximum value of the obtained equivalent circle diameter is set as the maximum value of the particle size of the metallic magnetic particles. With such a structure, the thickness of the insulating layer 70 can be ensured, thus improving the strength of the inductor. Furthermore, the specific characteristics related to the depth of the recess after threshing can also be applied to the inductor according to the first embodiment.

[0108] <Inductor Manufacturing Method of the First Embodiment>

[0109] While referring to Figure 10 The manufacturing method of the "inductor of the first embodiment" will be explained. Figure 10 This is a flowchart illustrating a method for manufacturing an inductor according to the present disclosure. The method for manufacturing an inductor according to the first embodiment may include a blank formation process, an exposure process, a de-granulation process, an external terminal formation process, and an insulating layer formation process. Hereinafter, the process will be described in detail.

[0110] -Blank Formation Process-

[0111] The green body forming step includes a laminate forming step of forming a laminate that constitutes the green body 10, and a firing step of firing the laminate.

[0112] • The laminate forming step

[0113] First, the magnetic layer S described in Figure 2 is prepared. The magnetic layer S is prepared by printing a magnetic paste containing the metal magnetic particles 10a having an average particle diameter of preferably 1 μm or more and 30 μm or less, more preferably 1 μm or more and 20 μm or less, and further preferably 1 μm or more and 10 μm or less, and repeating the coating.

[0114] Next, on the prepared magnetic layer S, a conductive paste that becomes the coil conductor 50 is printed, a conductive paste that becomes a conductor layer (or a via conductor) that connects the coil conductors 50 to each other is printed, a conductive paste that becomes the coil conductor connection portion 50v is printed, and a magnetic paste is printed on portions other than the coil conductors, the conductor layer, and the coil conductor connection portion. Thus, the laminate groups G1 to G7 described in Figure 2 are prepared. Furthermore, the prepared laminate groups G1 to G7 are laminated and pressure-bonded to form the laminate.

[0115] • The firing step

[0116] The formed laminate is fired after debinding that removes the binder contained in the magnetic paste and the conductive paste. The firing temperature is a temperature at which the laminate is fired to a certain extent, and can be set to about 700°C, for example. Furthermore, in order to improve the strength of the laminate, resin is impregnated into the laminate and cured. The resin that is impregnated into the laminate is an epoxy resin, but one or more kinds of resin selected from a group consisting of phenol resin, polyester resin, polyimide resin, polyolefin resin, silicone resin, acrylic resin, polyvinyl butyral resin, cellulose resin, and alkyd resin, etc. can be used. Through the above-described steps, the green body 10 that has the coil conductor 50 inside and contains the metal magnetic particles 10a and the resin is formed.

[0117] • The exposing step

[0118] The exposing step is a step of exposing the coil conductor connecting portion 50v electrically connected to the coil conductor 50 from the blank 10. Specifically, the coil conductor connecting portion 50v is exposed from the blank 10 by grinding the first main surface 11 of the blank 10, and electrical connection with the external terminal 30 described later is ensured. That is, the mounting surface side of the laminate is removed from the resin impregnated in the above-described laminate, and thus the coil conductor connecting portion 50v is exposed. Further, in order to adjust the shape of the blank 10, the second main surface 12, the first end surface 13, the second end surface 14, the first side surface 15, and / or the second side surface 16 of the blank 10 can also be ground. Here, the exposing step is not limited to the method based on grinding, and any method can be employed as long as the coil conductor connecting portion 50v can be exposed from the blank 10. As an example, the coil conductor connecting portion 50v can also be exposed from the blank 10 by chemically etching the blank 10.

[0119] -Deagglomeration step-

[0120] The deagglomeration step is a step of deagglomerating the metal magnetic particles 10a in the mounting surface (the first main surface 11) of the blank 10. Specifically, the metal magnetic particles 10a of the mounting surface (the first main surface 11) of the blank 10 are removed by immersing the blank 10 containing the metal magnetic particles 10a in an acidic solution. As an example of the acidic solution for removing the metal magnetic particles 10a, sulfuric acid is given. Further, after the metal magnetic particles 10a are deagglomerated by being immersed in the acidic solution, a thin resin film can be formed at the site, and an oxide film can be formed by oxidation treatment.

[0121] -Insulating layer forming step-

[0122] The insulating layer forming step is a step of forming the insulating layer 70 at least on the mounting surface (the first main surface 11) of the blank 10 except for the position where the coil conductor connecting portion 50v is exposed from the blank 10. Specifically, the insulating layer 70 can employ, for example, a resist resin having photosensitivity containing silica as a filler. The resist resin is applied to the entire mounting surface of the blank 10 by screen printing or the like. The photosensitive resist resin applied to the entire mounting surface is immersed in a developing solution after pattern exposure along the shape of the external terminal 30 described later, and the insulating layer 70 at the site where the external terminal 30 is formed is removed. Here, in manufacturing the inductor of the first embodiment, the insulating layer 70 is formed so as to have an overlapping region overlapping the blank 10 in a planar perspective view of the external terminal 30 from the mounting surface side of the blank 10. Further, in the above-described insulating layer forming step, the method using the resist resin having photosensitivity is described, but as an insulating layer forming method other than screen printing, a resist film can be attached to the mounting surface of the blank 10.

[0123] -External terminal forming step-

[0124] The external terminal forming step is a step of forming the external terminal at the degranulation site of the metal magnetic particle and the site where the coil conductor connecting portion is exposed from the green body. Specifically, the region of the mounting surface (first main surface 11) of the green body 10 from which the insulating layer 70 is removed is given a Pd catalyst, and the external terminal is formed by electroless plating. The structure of plating forms Cu plating at the coil conductor connecting portion. In addition to this, Ni-Sn, Ni-Au, Ni-Cu, Cu-Ni-Au, and the like are cited, but are not limited thereto. After the external terminal is formed, element singulation cutting is performed, and thus the inductor of the present embodiment can be manufactured.

[0125] As described above, according to the manufacturing method of the inductor described in the present embodiment, the metal magnetic particle is degranulated in the mounting surface of the green body, and the external terminal is formed at the degranulation site of the metal magnetic particle and the site where the coil conductor connecting portion is exposed from the green body, and thus plating growth caused by the metal magnetic particle can be reduced. Therefore, formation abnormalities of the external terminal can be reduced.

[0126] Manufacturing method of inductor of second embodiment

[0127] The manufacturing method of the "inductor of the second embodiment" will be described. Furthermore, in the manufacturing method of the inductor of the second embodiment, the green body forming step, the exposing step, and the degranulation step are substantially the same steps as those of the manufacturing method of the inductor of the first embodiment, and thus the description thereof will be omitted. In the following description, the points different from the manufacturing method of the inductor of the first embodiment described above will be described.

[0128] -Insulating layer forming step-

[0129] The insulating layer forming step of the manufacturing method of the inductor of the second embodiment forms the insulating layer 70 so that, in a planar perspective view observed from the mounting surface side of the green body 10, the external terminal 30 is disposed inside the exposed region E where the coil conductor connecting portion 50v is exposed from the green body 10. In other words, the insulating layer 70 is formed so that, in a planar perspective view observed from the mounting surface side of the green body 10, a portion of the coil conductor connecting portion 50v is covered.

[0130] -External terminal forming step-

[0131] The external terminal forming step forms the external terminal 30 inside the exposed region E (refer to Figure 6 , 7 ) where the coil conductor connecting portion 50v is exposed from the green body 10. In other words, the external terminal 30 is formed so as not to be in contact with the green body 10 and so as to be in contact only with the coil conductor connecting portion 50v.

[0132] As above, according to the manufacturing method of the inductor described in the present embodiment, in a plan view perspective observed from the mounting surface side of the blank 10, the external terminal 30 is disposed inside the exposed region E where the coil conductor connecting portion 50v is exposed from the blank 10, and the blank 10 is not brought into contact with the external terminal 30, so that even if the external terminal 30 is formed by plating, formation abnormalities of the external terminal 30 can be reduced.

[0133]

EXAMPLE

[0134] A detailed description is given of an experimental test related to the inductor of the present disclosure.

[0135] <Experimental Test 1: Composition Analysis>

[0136] Composition analysis based on EDX was performed for the examples and comparative examples shown below.

[0137] • Example

[0138] The inductor of the first embodiment shown in Figure 4 was subjected to the dehulling process shown in Figure 10 .

[0139] • Comparative Example

[0140] The inductor that was not subjected to the dehulling process shown in Figure 10 .

[0141] Composition analysis based on EDX was performed using an EDX (manufacturer name: JEOL Ltd., model number: JSM-7900F) with an observation magnification of 5000 times as the observation conditions.

[0142] The results of the composition analysis are shown in Figure 11 . According to the results of the composition analysis of Figure 11 , in the inductor of the example, it was confirmed that the position of the metal magnetic particle-containing blank was detected for the Fe element, and the case where an element constituting a plating component of the external terminal (for example, a Cu element) entered the recess in the blank after dehulling. On the other hand, in the inductor of the comparative example, the boundary between the Fe element as the metal magnetic particle and the element constituting the plating component of the external terminal (for example, a Cu element) was clearly known, and it was confirmed that the external terminal did not enter the blank.

[0143] <Experimental Test 2: SEM Observation 1>

[0144] SEM observation was performed for the inductor of the example and the inductor of the comparative example described above. SEM observation was performed using an SEM (manufacturer name: JEOL Ltd., model number: JSM-7900F) with an observation magnification of 1500 times and 5000 times as the observation conditions.

[0145] In Figure 12 , a schematic diagram of the SEM image is shown. Further, Figure 12 the schematic diagram shown indicates the vicinity of the boundary position of the green body containing the metal magnetic particles and the insulating layer. According to Figure 12 , it is possible to confirm the case where the insulating layer of the inductor of the example enters the recess after the degranulation of the metal magnetic particles. In particular, by magnifying to 5000 times, it is possible to confirm the entry of the insulating layer into the green body. On the other hand, for the inductor of the comparative example, the boundary of the insulating layer and the green body is clearly known, and the insulating layer does not enter the green body.

[0146] <Proof Test 3: SEM Observation 2>

[0147] In Proof Test 3, for the example and the comparative example, SEM observation was performed regarding the presence or absence of abnormal growth of plating. As the observation conditions, observation was performed at around 500 times.

[0148] In Figure 13 , a schematic diagram of the SEM image is shown. In the inductor of the comparative example, the average length of the metal magnetic particles in contact with the external terminal with respect to the length of the overlapping region exceeds 10%, and thus the influence of the metal magnetic particles 10a exposed on the surface of the green body is large, the plating formation mechanism for the green body 10 containing the metal magnetic particles 10a is different from the plating formation mechanism for the coil conductor connection portion 50v, and thus abnormal growth of plating occurs in the green body side of the external terminal. The "abnormal growth of plating" referred to in this specification means that the average thickness of the plating on the green body is thicker than the average thickness of the plating on the coil conductor connection region by 20% or more. On the other hand, in the inductor of the example, as will be described later in Proof Test 4, in the top perspective view observed from the mounting surface side of the green body, in the overlapping region where the external terminal and the green body overlap, the average length of the metal magnetic particles in contact with the external terminal with respect to the length of the overlapping region is 10% or less, and thus it is possible to confirm that abnormal growth of plating as in the inductor of the comparative example does not occur.

[0149] <Proof Test 4: SEM Observation 3>

[0150] In Proof Test 4, for the example, the contact ratio of the metal magnetic particles to the external terminal was calculated based on SEM observation. The calculation method is described in detail below.

[0151] (1) Along the imaginary line that passes through the external terminal and the coil conductor connection region of the mounting surface of the green body 10 and extends in the length direction L of the green body, a cut surface that is parallel to the height direction T (refer to Figure 1 ) of the green body 10 from the mounting surface (first main surface 11) side is prepared. This cut surface is prepared at three places in the width direction W (refer to Figure 1 ) of the green body.

[0152] (2) In each cross section, for each external terminal 30 in the first main surface of the blank 10, three points of the central and both ends of the external terminal, in which the distance from the coil conductor connection region to the front end is longer, in the portion of the external terminal 30 in which the coil conductor connection region and the portion extending outward from the coil conductor connection region on both sides of the coil conductor connection region are in contact with the blank 10, were photographed at a magnification of 5000 times using an SEM (manufacturer name: JEOL Ltd., model number: JSM-7900F) and an EDX (manufacturer name: JEOL Ltd., model number: JSM-7900F).

[0153] (3) In each photographed field of view, the composition of the metal magnetic particle 10a (for example, Fe) constituting the blank 10, the composition of the resin in the blank (for example, C), and the composition of the external terminal (Cu) were confirmed using the EDX, and the positional relationship of the metal magnetic particle, the blank, and the external terminal was confirmed.

[0154] Next, the image analysis software "Win RooF" (manufactured by Mitsui Bussan Corporation) was caused to read in the SEM image, and the outer edge of the external terminal was determined in the SEM image by image processing based on the composition image of the external terminal by EDX (for example, Cu composition image) (refer to the SEM photograph after image processing of Figure 14 ). Furthermore, the length of the outer edge of the metal magnetic particle side of the external terminal was calculated by image processing.

[0155] Next, the outer edge of the metal magnetic particle in which the metal magnetic particle was in contact with the external terminal without the resin around the metal magnetic particle was determined by image processing based on the composition image of the metal magnetic particle by EDX (for example, Fe composition image) and the composition image of the resin (for example, C composition image).

[0156] Furthermore, in the plurality of photographed fields of view for each external terminal, the proportion of the contact length of the metal magnetic particle in contact with the external terminal with respect to the length of the outer edge of the metal magnetic particle side of the external terminal was calculated for each, and the average thereof was calculated for all of the external terminals, whereby the contact ratio shown in Figure 14 was calculated.

[0157] The calculation result of the contact ratio of the metal magnetic particle to the external terminal is shown in Figure 14 . In any of the three positions of the photographed positions in the width direction of the blank, the contact ratio was confirmed to be 10% or less (position 1: 4%, position 2: 0%, position 3: 8%). Furthermore, in any of the three positions, the plating abnormal growth described in Test 3 was not confirmed.

[0158] As explained above, the inductor and the method for manufacturing the inductor disclosed herein can reduce abnormalities in the formation of external terminals and improve the yield of the inductor.

[0159] Furthermore, the embodiments disclosed herein are illustrative in all respects and are not intended as a basis for limiting interpretation. For example, in the embodiments described above, a coil constructed by stacking coil conductors is disclosed, but it is not limited to this coil; it may also be a coil constructed by winding wires. More specifically, a hollow coil may be embedded with the winding shaft perpendicular to the mounting surface of the blank, wherein the hollow coil is formed by winding two layers in a spiral shape with the lead-out portions of the wires at the beginning and end of winding located on the outer periphery.

[0160] Furthermore, in the inductor of the first embodiment and the inductor of the second embodiment, a different type may be used instead. Figures 15-17 The blank 10 and the external terminals 30 are shown in the following description. The blank 10 and the external terminals 30 will be described in detail below.

[0161] -Blank-

[0162] Figure 15 The blank 10 shown has a third external terminal 33 electrically connected to one end of the second coil 22 and a fourth external terminal 34 electrically connected to the other end of the second coil 22 disposed on the second main surface 12. In addition, the third external terminal 33 and the fourth external terminal 34 are disposed along the long side (or short side) of the second main surface 12.

[0163] and, Figure 15 The blank 10 shown has a first external terminal 31 electrically connected to one end of the first coil 21 and a second external terminal 32 electrically connected to the other end of the first coil 21 on its first main surface 11. In addition, the first external terminal 31 and the second external terminal 32 are arranged along the long side (or short side) of the first main surface 11.

[0164] Figure 15 The blank 10 shown can be made by making Figure 16 The stacked groups G1 to G9 shown are stacked together. Hereinafter, stacked groups G1 to G9 will be described in detail; however, regarding the above-mentioned... Figure 2 Common elements are labeled with the same reference numerals, and descriptions are omitted where appropriate.

[0165] The stacked assembly G1 forms the second main surface 12 of the blank 10. Furthermore, a third external terminal 33 and a fourth external terminal 34 are arranged along the long side (or short side) of the second main surface 12.

[0166] Corresponding to the configuration of the stacked assembly G2 with the third external terminal 33 and the fourth external terminal 34, a third coil conductor connection portion 53v and a fourth coil conductor connection portion 54v are provided.

[0167] The second coil conductor 52 is configured to form the second coil 22 through the stacked group G3 and the stacked group G4.

[0168] The stacked assembly G5 is provided with a magnetic layer S for electrically insulating the first coil 21 from the second coil 22.

[0169] The first coil conductor 51 is configured to form the first coil 21 through the stacked group G6 and the stacked group G7.

[0170] Corresponding to the configuration of the first external terminal 31 and the second external terminal 32, the stacked assembly G8 is provided with a first coil conductor connection portion 51v and a second coil conductor connection portion 52v.

[0171] The stacked assembly G9 forms the first main surface 11 of the blank 10. Furthermore, a first external terminal 31 and a fourth external terminal 32 are arranged along the long side (or short side) of the first main surface 11.

[0172] In addition, the insulating layer 70 covers the mounting surfaces (first main surface 11 and second main surface 12) of the blank 10, excluding the external terminal 30.

[0173] In the inductor described above, as in the inductor of the first embodiment, in the cut surface cut along the length direction of the blank 10 in the height direction of the blank 10 from the mounting surface (first main surface 11 and / or second main surface 12) of the blank 10 through the connection area CL between the external terminal 30 and the coil conductor, the average length of the contact between the metal magnetic particle 10a and the external terminal 30 is less than 10% of the length of the overlap area OL of the external terminal 30. Therefore, plating growth caused by the metal magnetic particle can be reduced, and abnormalities in the formation of the external terminal can be reduced.

[0174] Furthermore, in the inductor described above, as explained in the inductor of the second embodiment, the external terminals can be positioned inside the exposed area of ​​the coil conductor from the mounting surface of the blank in a top-view perspective. With this type of inductor, contact between metallic magnetic particles and the external terminals can be prevented, reducing the likelihood of abnormal external terminal formation.

[0175] Furthermore, in the inductor of the first embodiment and the inductor of the second embodiment, a different type may be used instead. Figures 18-19 The blank 10 and the external terminals 30 are shown in the following description. The blank 10 and the external terminals 30 will be described in detail below.

[0176] -Blank-

[0177] Figure 18The blank 10 shown has a first external terminal 31 electrically connected to one end of the first coil 21 and a fourth external terminal 34 electrically connected to one end of the second coil 22 on its second main surface 12. In addition, the first external terminal 31 and the fourth external terminal 34 are arranged on opposite sides of the second main surface 12.

[0178] and, Figure 18 The blank 10 shown has a second external terminal 32 electrically connected to the other end of the first coil 21 and a third external terminal 33 electrically connected to the other end of the second coil 22 on its first main surface 11. In addition, the second external terminal 32 and the third external terminal 33 are arranged on the diagonal of the first main surface 11 (a diagonal different from the diagonal of the second main surface 12).

[0179] By making Figure 19 The stacked groups G1 to G9 shown are stacked to form a structure. Figure 18 The blank 10 shown. Hereinafter, the laminate groups G1 to G9 will be described in detail; however, regarding the above-mentioned... Figure 2 or Figure 16 Common elements are labeled with the same reference numerals, and descriptions are omitted where appropriate.

[0180] The laminated group G1 constitutes the second main surface 12 of the blank 10. Furthermore, a first external terminal 31 and a fourth external terminal 34 are arranged on the diagonal of the second main surface 12.

[0181] Corresponding to the configuration of the first external terminal 31 and the fourth external terminal 34, the stacked assembly G2 is provided with a first coil conductor connection portion 51v and a fourth coil conductor connection portion 54v.

[0182] First coil conductors 51 are arranged in a portion of stacked groups G3, G5, and G7 to form a first coil 21. More specifically, in a top view of stacked group G3, the first coil conductors 51 are arranged along both sides of the magnetic layer S that forms the corner corresponding to the second external terminal 32; in a top view of stacked group G5, the first coil conductors 51 are arranged along three sides of a continuous magnetic layer S that includes the corner corresponding to the third external terminal 33 and the corner corresponding to the fourth external terminal 34; and in a top view of stacked group G7, the first coil conductors 51 are arranged along three sides of a continuous magnetic layer S that includes the corner corresponding to the first external terminal 31 and the corner corresponding to the second external terminal 32. Each first coil conductor 51 is electrically connected to each other through a through-hole conductor V.

[0183] Also, the second coil conductors 52 are arranged in a portion of the stacked group G3, the stacked group G5, and the stacked group G7 to constitute the second coil 22. More specifically, the second coil conductors 52 are arranged along two sides of the magnetic layer S constituting the corner portion corresponding to the third external terminal 33 in the planar perspective of the stacked group G3, the second coil conductors 52 are arranged along three sides of the continuous magnetic layer S including the corner portion corresponding to the first external terminal 31 and the corner portion corresponding to the second external terminal 32 in the planar perspective of the stacked group G5, and the second coil conductors 52 are arranged along three sides of the continuous magnetic layer S including the corner portion corresponding to the third external terminal 33 and the corner portion corresponding to the fourth external terminal 34 in the planar perspective of the stacked group G7. The respective second coil conductors 52 are electrically connected to each other by the via conductors V.

[0184] With respect to the arrangement relationship of the above-described first coil conductors 51 and the second coil conductors 52, in other words, the first coil conductors 51 and the second coil conductors 52 are in a point-symmetrical relationship with the center of each of the stacked groups G3, G5, and G7 as an axis.

[0185] The stacked group G8 is arranged with the second coil conductor connection portion 52v and the third coil conductor connection portion 53v corresponding to the arrangement of the second external terminal 32 and the third external terminal 33.

[0186] The stacked group G9 constitutes the first main surface 11 of the blank 10. Also, the second external terminal 32 and the third external terminal 33 are arranged on the diagonal line of the first main surface 11.

[0187] In addition, the insulating layer 70 covers the surface of the mounting surface (the first main surface 11 and the second main surface 12) of the blank 10 except for the external terminals 30.

[0188] In the above-described inductor, as described in the inductor of the first embodiment, in a cut surface cut in the height direction of the blank 10 along the length direction of the blank 10 at a position passing through the external terminal 30 and the coil conductor connection region CL from the mounting surface (the first main surface 11 and / or the second main surface 12) side of the blank 10, the average length of the metal magnetic particles 10a in contact with the external terminal 30 with respect to the length of the overlapping region OL of the external terminal 30 is 10% or less. Thus, plating growth due to the metal magnetic particles can be reduced, and formation abnormalities of the external terminal can be reduced.

[0189] Further, in the above-described inductor, as described in the inductor of the second embodiment, the external terminal can also be arranged at a position inside the exposed region in which the coil conductor is exposed from the blank in the planar perspective viewed from the mounting surface side of the blank. If it is the inductor of the second embodiment, the metal magnetic particles can be prevented from coming into contact with the external terminal, and formation abnormalities of the external terminal can be reduced.

[0190] In addition, the technical scope of the present disclosure is not construed only by the above-described embodiments, but is defined based on the recitations of the claims. In addition, the technical scope of the present disclosure includes all modifications equivalent in meaning and within the scope of the claims.

[0191] The inductor of the present disclosure and the manufacturing method of the inductor include the following modes.

[0192] <1>

[0193] An inductor, wherein:

[0194] a green body having a coil conductor inside, containing a metal magnetic particle and a resin; and

[0195] an external terminal provided on a mounting surface of the green body, electrically connected to the coil conductor,

[0196] the green body has a first main surface and a second main surface opposite in a height direction, a first end surface and a second end surface opposite in a length direction orthogonal to the height direction, and a first side surface and a second side surface opposite in a width direction orthogonal to the length direction and the height direction,

[0197] the external terminal has a coil conductor connection region on a region where the coil conductor is exposed from the green body in a planar perspective view from the mounting surface side of the green body, and an overlapping region overlapping the green body,

[0198] in a cut surface cut in the height direction of the green body along the length direction of the green body at a position passing through the external terminal and the coil conductor connection region from the mounting surface side of the green body, an average length of the metal magnetic particle in contact with the external terminal is 10% or less relative to a length of the overlapping region of the external terminal.

[0199] <2>

[0200] An inductor, wherein:

[0201] a green body having a coil conductor inside, containing a metal magnetic particle and a resin; and

[0202] an external terminal provided on a mounting surface of the green body, electrically connected to the coil conductor,

[0203] in a planar perspective view from the mounting surface side of the green body, the external terminal is disposed inside a region where the coil conductor is exposed from the green body.

[0204] <3>

[0205] The inductor according to any one of <1> to <3>, wherein

[0206] The metal magnetic particles are degranulated in a surface of the green body other than the mounting surface.

[0207] <4>

[0208] The inductor according to any one of <1> to <3>, wherein

[0209] The metal magnetic particles are degranulated in a surface of the green body other than the mounting surface.

[0210] <5>

[0211] The inductor according to any one of <1>, <3> or <4> which refers to <1> and does not refer to <2>, wherein

[0212] The external terminal enters a recess after the degranulation of the metal magnetic particles in the mounting surface of the green body.

[0213] <6>

[0214] The inductor according to any one of <1> to <5>, wherein

[0215] An insulating layer is provided on the mounting surface of the green body, and the insulating layer covers surfaces other than a surface in contact with the external terminal.

[0216] <7>

[0217] The inductor according to <6>, wherein

[0218] The insulating layer enters a recess after the degranulation of the metal magnetic particles in the mounting surface of the green body.

[0219] <8>

[0220] The inductor according to any one of <1> to <7>, wherein

[0221] A depth of the recess after the degranulation of the metal magnetic particles is equal to or greater than a maximum particle diameter of the metal magnetic particles and equal to or less than twice the maximum particle diameter.

[0222] <9>

[0223] A method of manufacturing an inductor, comprising:

[0224] A green body formation step of forming a green body having a coil conductor inside, the green body containing metal magnetic particles and a resin;

[0225] An exposing step of exposing an external terminal connection area of the coil conductor from the green body;

[0226] a degranulation process of degranulating the metal magnetic particles in the mounting surface of the green body; and

[0227] an external terminal forming process of forming an external terminal at a degranulation site of the metal magnetic particles degranulated by the degranulation process and a site of the external terminal connection region of the coil conductor exposed by the exposing process.

[0228] <10>

[0229] A method of manufacturing an inductor, comprising:

[0230] a green body forming process of forming a green body having a coil conductor inside, containing metal magnetic particles and a resin;

[0231] an exposing process of exposing an external terminal connection region of the coil conductor from the green body; and

[0232] an external terminal forming process of forming an external terminal inside an exposed region of the external terminal connection region of the coil conductor exposed from the green body.

[0233] <11>

[0234] The method of manufacturing an inductor according to any one of <9> to <10>, wherein

[0235] comprising an insulating layer forming process of forming an insulating layer on a surface of the mounting surface of the green body other than a surface in contact with the external terminal.

[0236] <12>

[0237] The method of manufacturing an inductor according to any one of <9> to <11>, wherein

[0238] the green body forming process comprises:

[0239] a process of forming a laminate by laminating a magnetic layer containing the coil conductor and the metal magnetic particles; and

[0240] a firing process of firing the laminate.

[0241] <13>

[0242] The method of manufacturing an inductor according to any one of <9> to <12>, wherein

[0243] the exposing process is performed by grinding the mounting surface of the green body.

[0244] <14>

[0245] The method of manufacturing an inductor according to <9>, <11> or <12> reciting <9>, wherein

[0246] The above dehulling process is performed by etching based on an acidic solution.

[0247] <15>

[0248] The method for manufacturing an inductor according to any one of <9> to <14>, wherein

[0249] The above external terminal forming process is performed by electroless plating.

[0250] Industrial applicability

[0251] The present disclosure can be used for an inductor in which formation abnormalities of external terminals are reduced.

[0252] Explanation of reference numerals

[0253] 1… inductor; 10… green body; 10a… metal magnetic particle; 11… first main face; 12… second main face; 13… first end face; 14… second end face; 15… first side face; 16… second side face; 21… first coil; 22… second coil; 30… external terminal; 31… first external terminal; 32… second external terminal; 33… third external terminal; 34… fourth external terminal; 50… coil conductor; 51… first coil conductor; 52… second coil conductor; 50v… coil conductor connecting portion; 51v… first coil conductor connecting portion; 52v… second coil conductor connecting portion; 53v… third coil conductor connecting portion; 54v… fourth coil conductor connecting portion; G1 to G7… stacked group; 70… insulating layer; S… magnetic layer; OL… overlapping region; CL… coil conductor connecting region; E… exposed region.

Claims

1. An inductor, wherein, have: The blank contains coil conductors, metallic magnetic particles, and resin; and External terminals are disposed on the mounting surface of the aforementioned blank and are electrically connected to the aforementioned coil conductor. The aforementioned billet has: a first main surface and a second main surface opposite each other in the height direction; a first end surface and a second end surface opposite each other in the length direction orthogonal to the height direction; and a first side surface and a second side surface opposite each other in the width direction orthogonal to both the length and height directions. The aforementioned external terminal has a coil conductor connection area located on the exposed area where the coil conductor is exposed from the blank in a top perspective view viewed from the mounting surface side of the blank, and an overlapping area that overlaps with the blank. In a cut surface that is cut along the length direction of the blank and in the height direction of the blank from the mounting surface side of the blank through the external terminal and the coil conductor connection area, the average length of the contact between the metal magnetic particle and the external terminal is less than 10% of the length of the overlapping area of ​​the external terminal.

2. An inductor, wherein, have: The blank contains coil conductors, metallic magnetic particles, and resin; and External terminals are disposed on the mounting surface of the aforementioned blank and are electrically connected to the aforementioned coil conductor. In a top-view perspective view taken from the mounting surface side of the aforementioned blank, the aforementioned external terminal is disposed inside the exposed area where the coil conductor is exposed from the aforementioned blank.

3. The inductor according to claim 1 or 2, wherein, The aforementioned magnetic metal particles are granulated on the aforementioned mounting surface of the aforementioned blank.

4. The inductor according to any one of claims 1 to 3, wherein, The aforementioned magnetic metal particles are granulated on surfaces other than the mounting surface of the aforementioned blank.

5. The inductor according to claim 1, or claim 3 or claim 4 which refers to claim 1 but not claim 2, wherein, The aforementioned external terminal enters the recess in the mounting surface of the aforementioned blank after the aforementioned metal magnetic particles have been threshed.

6. The inductor according to any one of claims 1 to 5, wherein, An insulating layer is provided on the mounting surface of the above-mentioned blank, and the insulating layer covers the surface except for the surface that contacts the above-mentioned external terminal.

7. The inductor according to claim 6, wherein, The aforementioned insulating layer enters the recess in the mounting surface of the aforementioned blank after the aforementioned metallic magnetic particles have been threshed.

8. The inductor according to any one of claims 1 to 7, wherein, The depth of the recess after the aforementioned metallic magnetic particles are threshed is above the maximum particle size of the aforementioned metallic magnetic particles and less than twice the maximum particle size.

9. A method for manufacturing an inductor, wherein, have: The blank forming process forms a blank, which contains coil conductors, metallic magnetic particles, and resin. The exposure process exposes the external terminal connection area of ​​the coil conductor from the blank. The threshing process involves threshing the aforementioned magnetic metal particles from the mounting surface of the aforementioned billet; and The external terminal forming process forms an external terminal at the shaving portion where the metal magnetic particles are shaving in the shaving process described above, and at the external terminal connection area of ​​the coil conductor exposed in the exposure process described above.

10. A method for manufacturing an inductor, wherein, have: The blank forming process forms a blank, which contains coil conductors, metallic magnetic particles, and resin. The exposure process exposes the external terminal connection area of ​​the coil conductor from the blank; and In the external terminal forming process, an external terminal is formed inside the exposed area of ​​the coil conductor that is exposed from the blank.

11. The method of manufacturing an inductor according to claim 9 or 10, wherein, It includes an insulating layer forming process, in which an insulating layer is formed on the mounting surface of the above-mentioned blank, excluding the surface that contacts the above-mentioned external terminal.

12. The method for manufacturing an inductor according to any one of claims 9 to 11, wherein, The above-mentioned billet forming process includes: The process of stacking magnetic layers containing the aforementioned coil conductor and the aforementioned metallic magnetic particles to form a laminate; and The firing process involves firing the aforementioned laminated body.

13. The method for manufacturing an inductor according to claim 9 or 10, wherein, The above-mentioned exposure process is performed by grinding the mounting surface of the blank.

14. The method of manufacturing an inductor according to claim 9, or claim 11 or claim 12 which refers to claim 9, wherein, The above-mentioned de-granulation process is carried out by etching based on an acidic solution.

15. The method for manufacturing an inductor according to any one of claims 9 to 14, wherein, The above-mentioned external terminal forming process is performed by electroless plating.

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