Inductors and methods for manufacturing inductors

Abstract

The present invention provides an inductor and a method for producing an inductor which reduce formation abnormalities in an external terminal. An inductor 1 according to the present disclosure which comprises an element body 10 that includes a coil conductor 50 therein and contains metal magnetic particles 10a and a resin, and further comprises an external terminal 30 which is provided on a mounting surface (first main surface 11) of the element body 10 and is electrically connected to the coil conductor 50, wherein: the element body 10 has a first main surface 11 and a second main surface 12 that face each other in the height direction, a first end surface 13 and a second end surface 14 that are orthogonal to the height direction and face each other in the lengthwise direction, and a first side surface 15 and a second side surface 16 that face each other in the widthwise direction, which is orthogonal to the lengthwise direction and the height direction; the external terminal 30 has a coil conductor connection region CL positioned in an exposed region in which a coil conductor 50 is exposed from the element body 10 in a plan view seen from the mounting surface side of the element body 10, and an overlap region OL which overlaps the element body; and the length of contact between the metal magnetic particles 10a and the external terminal 30 is 10% or less of the average length of the overlap region OL of the external terminal 30 along a cut surface obtained by cutting in the height direction of the element body 10 along the lengthwise direction of the element body 10 at a position which passes through the external terminal 30 and the coil conductor connection region CL from the mounting surface side of the element body 10.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an inductor including a composite body made of a composite material of resin and metal magnetic powder, an internal electrode provided in the composite body and having an end face exposed from the outer surface of the composite body, and an external terminal electrically connected to the internal electrode. Further, according to FIG. 1 of Patent Document 1, it can be seen that in a plan view, the planar area of the external terminal is larger than the planar area of the internal electrode. That is, it can be grasped that the external terminal is in contact with the composite body containing metal magnetic powder.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The external terminal of the inductor is electrically connected to the electrode of the mounting substrate on which the inductor is mounted. When mounting the inductor on the mounting substrate, it may be desirable to increase the planar area of the external terminal from the perspective of alignment with the mounting substrate. When the planar area of the external terminal is increased, the composite body (the basic body of the inductor) disposed around the internal electrode and the external terminal come into contact with each other.

[0005] Here, when external terminals are formed by plating (for example, electroless plating), the plating formation mechanism for internal electrodes is different from the plating formation mechanism for composite bodies containing metal magnetic powder. In other words, when external terminals are formed by plating, plating growth occurs due to the metal magnetic powder contained in the composite body, leading to abnormalities in the formation of the external terminals, which could reduce the yield of the inductor.

[0006] This disclosure has been made in view of the above issues. Specifically, the primary purpose of this disclosure is to provide an inductor and a method for manufacturing an inductor that reduces abnormalities in the formation of external terminals. [Means for solving the problem]

[0007] The inductor disclosed herein is A base body containing a coil conductor, metallic magnetic particles, and resin, The above-mentioned body is provided with an external terminal on its mounting surface that is electrically connected to the coil conductor, The aforementioned body has a first principal surface and a second principal surface that are opposite to each other in the height direction, a first end surface and a second end surface that are perpendicular to the height direction and opposite to each other in the length direction, and a first side surface and a second side surface that are perpendicular to the length direction and the height direction and opposite to each other in the width direction, The external terminal has a coil conductor connection region located on an exposed region where the coil conductor is exposed from the base body in a planar perspective view from the mounting surface side of the base body, and an overlapping region that overlaps with the base body. The average length of contact between the metal magnetic particles and the external terminals is 10% or less of the length of the overlap region of the external terminals in the cross-section obtained by cutting the body in the height direction along the length direction of the body from the mounting surface side of the body, at a position passing through the connection area between the external terminals and the coil conductor.

[0008] Furthermore, the inductor of this disclosure is A base body containing a coil conductor inside, metal magnetic particles, and resin, The above-mentioned body is provided with an external terminal on its mounting surface that is electrically connected to the coil conductor, In a planar perspective view from the mounting surface of the base body, the external terminals are positioned inside the exposed region where the coil conductor is exposed from the base body.

[0009] The method for manufacturing an inductor in this disclosure is: A process for forming a substrate that has a coil conductor inside and contains metal magnetic particles and resin, An exposure step in which the external terminal connection area of ​​the coil conductor is exposed from the base body, A degranulation step in which the metal magnetic particles are removed from the mounting surface of the base body, An external terminal forming step is performed to form external terminals at the locations where metal magnetic particles have been removed by the aforementioned degranulation step and at the locations of the external terminal connection region of the coil conductor that have been exposed by the aforementioned exposure step. It is equipped with.

[0010] Furthermore, the method for manufacturing the inductor of this disclosure is A process for forming a substrate that has a coil conductor inside and contains metal magnetic particles and resin, An exposure step in which the external terminal connection area of ​​the coil conductor is exposed from the base body, An external terminal forming step is performed to form an external terminal inside the exposed region where the external terminal connection region of the coil conductor is exposed from the base body, It is equipped with. [Effects of the Invention]

[0011] This disclosure provides an inductor and a method for manufacturing an inductor that reduces abnormalities in the formation of external terminals. More specifically, in the inductor of this disclosure, the average length of contact between the metal magnetic particles and the external terminals is 10% or less of the length of the overlap region of the external terminals in the cross-section obtained by cutting the body in the height direction along the length direction of the body from the mounting surface side of the body at a position passing through the connection area between the external terminals and the coil conductor. Therefore, plating growth caused by the metal magnetic particles can be reduced. Consequently, abnormalities in the formation of external terminals can be reduced.

[0012] Also, in another inductor of the present disclosure, in a plan view perspective seen from the side of the mounting surface of the base body, since the external terminals are arranged inside the exposed area where the coil conductor is exposed from the base body, it is possible to prevent the metal magnetic particles from contacting the external terminals and reduce abnormal formation of the external terminals.

Brief Description of the Drawings

[0013] [Figure 1] FIG. 1 is a perspective view of the inductor of the present disclosure. [Figure 2] FIG. 2 is an exploded perspective view of the inductor of the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken in the direction of the arrow along line III-III of FIG. 2. [Figure 4] FIG. 4 is an enlarged cross-sectional view of the main part of FIG. 3. [Figure 5] FIG. 5 is an exploded perspective view of the inductor of the second embodiment. [Figure 6] FIG. 6 is a cross-sectional view taken in the direction of the arrow along line VI-VI of FIG. 5. [Figure 7] FIG. 7 is an enlarged cross-sectional view of the main part of FIG. 6. [Figure 8] FIG. 8 is an enlarged cross-sectional view of the main part of the inductor of a modification of the second embodiment. [Figure 9] FIG. 9 is a cross-sectional view of the inductor of another embodiment. [Figure 10] FIG. 10 is a flowchart showing a method for manufacturing the inductor of the present disclosure. [Figure 11] FIG. 11 is an elemental analysis photograph for explaining the elemental analysis results. [Figure 12] FIG. 12 is a cross-sectional view for explaining the state of demixing of the metal magnetic particles. [Figure 13] FIG. 13 is a cross-sectional view for explaining the state of plating formation. [Figure 14] FIG. 14 is a cross-sectional photograph for explaining the contact state between the metal magnetic particles and the external terminals. [Figure 15] FIG. 15 is a perspective view of another embodiment of the inductor of the present disclosure. [Figure 16]Figure 16 is an exploded perspective view of another embodiment of the inductor of the present disclosure. [Figure 17] Figure 17 is a cross-sectional view taken along the line XVII-XVII in Figure 16. [Figure 18] Figure 18 is a perspective view of yet another embodiment of the inductor of the present disclosure. [Figure 19] Figure 19 is an exploded perspective view of yet another embodiment of the inductor of the present disclosure. [Modes for carrying out the invention]

[0014] The inductors of this disclosure are described below. However, this disclosure is not limited to the configurations described below and may be modified as appropriate without departing from the gist of this disclosure. Furthermore, combinations of several of the preferred configurations described below also constitute this disclosure.

[0015] The inductor of this disclosure can be used, for example, in a DC-DC converter. Furthermore, the inductor of this disclosure is also applicable to applications other than DC-DC converters.

[0016] In this specification, terms describing relationships between elements (e.g., "parallel," "orthogonal," etc.) and terms describing the shape of elements mean not only strictly defined aspects but also substantially equivalent ranges, such as ranges with differences of a few percent. In this specification, the direction in which the magnetic layers and coil conductors constituting the element are stacked is referred to as the "stacking direction."

[0017] Furthermore, any references to direction or orientation in this specification are solely for explanatory purposes and are not intended to limit the scope of this disclosure unless explicitly stated otherwise. For example, relative terms such as "outside (or outside, external, or outer perimeter)" and "inside (or inside, internal, or inner perimeter)," as well as their derived terms, should be understood to refer to the direction as described or illustrated. In other words, unless explicitly stated otherwise, the invention is not required to be limited to a specific direction, orientation, or form. Similarly, terms such as "provided," "arranged," "connected," "attached," and "pasted," as well as their derived terms, may refer not only to direct embodiments but also to embodiments involving other elements such as intervening objects, unless explicitly stated otherwise.

[0018] The drawings shown below are schematic representations, and their dimensions, aspect ratios, and scales may differ from those of the actual product.

[0019] <Inductor of the first embodiment> A first embodiment of the inductor of this disclosure will be described with reference to Figures 1 to 4. Figure 1 is a perspective view of the inductor of this disclosure, Figure 2 is an exploded perspective view of the inductor of the first embodiment, Figure 3 is a cross-sectional view taken along the line III-III in Figure 2, and Figure 4 is an enlarged cross-sectional view of the main part of Figure 3. Note that the shape and arrangement of the inductor and its components are not limited to the examples shown.

[0020] The inductor 1 of this disclosure comprises a base body 10 containing a coil conductor 50 inside and metal magnetic particles 10a and resin, and an insulating layer 70 provided on the mounting surface (first main surface 11) of the base body 10, in an area where the external terminals 30 of the mounting surface of the base body 10 containing the coil conductor 50 are not provided. Coil conductor 50 It includes an external terminal 30 that is electrically connected to it.

[0021] In this embodiment, the base body 10 includes a first coil 21 and a second coil 22 located above the first coil 21 in the height direction T. The coils inside the base body 10 are not limited to the above configuration; it may also include one coil or two or more coils. For example, as shown in Figure 9, the base body 10 may include four coils. Furthermore, the first coil 21 may be constructed by stacking multiple stacking groups G4 and G5 (see Figure 2), which will be described later, so that the first coil conductor 51 is wound spirally around via conductors (not shown). The second coil 22 may be constructed by stacking multiple stacking groups G2 and G3 (see Figure 2), which will be described later, so that the second coil conductor 52 is wound spirally around via conductors (not shown). Each component will be described in detail below.

[0022] -Base model- The base body 10 is, for example, a rectangular prism shape or a roughly rectangular prism shape having six faces. The corners and edges of the base body 10 may be rounded. The corners are the parts where three faces of the base body 10 intersect, and the edges are the parts where two faces of the base body 10 intersect.

[0023] Figure 1 shows the length, width, and height directions of the inductor 1 and the base body 10 as the L, W, and T directions, respectively. The length L, width W, and height T are orthogonal to each other. The mounting surface of the inductor 1 is, for example, a surface parallel to the length L and width W (LW surface).

[0024] The base body 10 shown in Figure 1 has a first main surface 11 and a second main surface 12 that are opposite to the height direction T, a first end surface 13 and a second end surface 14 that are perpendicular to the height direction T and opposite to the length direction L, and a first side surface 15 and a second side surface 16 that are perpendicular to the length direction L and the height direction T and opposite to the width direction W. In the example shown in Figure 1, the first main surface 11 of the base body 10 corresponds to the mounting surface (bottom surface) of the base body 10. The second main surface 12 may also be the mounting surface of the base body 10.

[0025] The base body 10 includes a magnetic layer S and a coil conductor 50 (see Figure 2). The base body 10 may also have a laminated structure. Specifically, the base body 10 may include multiple magnetic layers S and coil conductors 50 in the lamination direction (e.g., the height direction T). In this embodiment, as shown in Figure 2, it is constructed by laminating lamination groups G1 to G7, each containing at least one magnetic layer S and a coil conductor 50 (or only the magnetic layer S). The boundaries between each layer of the laminated structure of the base body 10 are lost. Furthermore, each lamination group layer may be constructed by laminating multiple identical patterns.

[0026] The laminated group G1 has a magnetic layer S and constitutes the second main surface 12 of the base body 10.

[0027] The laminated group G2 is provided with a magnetic layer S and a second coil conductor 52 which constitutes part of the second coil 22. The second coil conductor 52 of laminated group G2 constitutes one winding of the second coil 22. More specifically, the second coil conductor 52 is arranged along the approximate outer edge of the magnetic layer S. In addition, one end of the second coil conductor 52 is provided with a conductor layer (or via conductor) (not shown) for connection to the second coil conductor 52 of laminated group G3, and the other end of the second coil conductor 52 is provided with a fourth coil conductor connection portion (not shown) for electrical connection to the fourth external terminal 34.

[0028] The laminated group G3 is provided with a magnetic layer S and a second coil conductor 52 which constitutes part of the second coil 22. 3 The second coil conductor 52 constitutes the other windings of the second coil 22. One end of the second coil conductor 52 is connected to the second coil conductor 52 of the laminated group G2, and the other end of the second coil conductor 52 is provided with a third coil conductor connection portion (not shown) for electrical connection to the third external terminal 33. In addition, a fourth coil conductor connection portion 54v is provided in a corner of the magnetic layer S that is away from the second coil conductor 52 in a plan view, so as to be electrically connected to a fourth coil conductor connection portion (not shown) of the laminated group G2.

[0029] The laminated group G4 is provided with a magnetic layer S and a first coil conductor 51 that constitutes part of the first coil 21. The first coil conductor 51 of laminated group G4 constitutes one winding of the first coil 21. One end of the first coil conductor 51 is provided with a conductor layer (or via conductor) (not shown) for connection to the first coil conductor 51 of laminated group G5, and the other end of the first coil conductor 51 is provided with a second coil conductor connection portion (not shown) for electrical connection to the second external terminal 32. In addition, in the magnetic layer S, each corner away from the first coil conductor 51 in a plan view is provided with a fourth coil conductor connection portion 54v for electrical connection to the fourth coil conductor connection portion of laminated group G3, and a third coil conductor connection portion 53v for electrical connection to the third coil conductor connection portion of laminated group G3.

[0030] The laminated group G5 is provided with a magnetic layer S and a first coil conductor 51 that constitutes part of the first coil 21. The first coil conductor 51 of laminated group G5 constitutes the other windings of the first coil 21. One end of the first coil conductor 51 is connected to the first coil conductor 51 of laminated group G4, and the other end of the first coil conductor 51 is provided with a first coil conductor connection portion (not shown) for electrical connection to the first external terminal 31. In addition, in the magnetic layer S, each corner away from the first coil conductor 51 in a plan view is provided with a fourth coil conductor connection portion 54v for electrical connection to the fourth coil conductor connection portion 54v of laminated group G4, a third coil conductor connection portion 53v for electrical connection to the third coil conductor connection portion 53v of laminated group G4, and a second coil conductor connection portion 52v for electrical connection to the second coil conductor connection portion 52v of laminated group G4.

[0031] The laminated group G6 is provided with a first coil conductor connection portion 51v, a second coil conductor connection portion 52v, a third coil conductor connection portion 53v, and a fourth coil conductor connection portion 54v in the magnetic layer S and at its corners.

[0032] The laminated group G7 is provided with a first coil conductor connection section 51v, a second coil conductor connection section 52v, a third coil conductor connection section 53v, and a fourth coil conductor connection section 54v in the magnetic layer S and corners, which have a larger planar area than the first to fourth coil conductor connection sections of the laminated group G6. By making the planar area of ​​the first to fourth coil conductor connection sections of the laminated group G7 larger than that of the first to fourth coil conductor connection sections of the laminated group G6, the alignment of the coil conductor connection sections can be easily performed.

[0033] As described above, if the base body 10 has a laminated structure comprising laminated groups G1 to G7, the design freedom of the inductor 1 is increased. For example, when manufacturing an inductor 1 having a first external terminal 31, a second external terminal 32, a third external terminal 33, and a fourth external terminal 34 on the bottom surface (first main surface 11) of the base body 10, it becomes easier to pull out the first coil 21 and the second coil 22 to the bottom surface side. The laminated structure comprising the laminated groups G1 to G7 may also be formed by stacking the materials constituting the magnetic layer S, the materials constituting the coil conductor 50, and the materials constituting the coil conductor connection part 50v sequentially by printing (e.g., screen printing) from the second main surface 12 side or the first main surface 11 side of the base body 10. In this case, each of the laminated groups G1 to G7 may be repeatedly printed until the magnetic layer S, coil conductor 50, and coil conductor connection part 50v reach the desired thickness.

[0034] The magnetic layer S contains metallic magnetic particles 10a (see Figure 4) composed of a magnetic material. The metallic magnetic particles 10a may contain Fe and / or Si. More specifically, they may be Fe particles or Fe alloy particles. Examples of Fe alloys include Fe-Si alloys, Fe-Si-Cr alloys, Fe-Si-Al alloys, Fe-Si-BP-Cu-C alloys, Fe-Si-B-Nb-Cu alloys, etc. The metallic magnetic particles 10a may also contain impurities such as Cr, Mn, Cu, Ni, P, S, or Co that are not intended during manufacturing. Furthermore, the metallic magnetic particles 10a may be contained in the magnetic paste, as will be described in detail in the manufacturing method section. Therefore, the metallic magnetic particles may contain elements that are more easily oxidized than Fe added during the production of the magnetic paste (e.g., Cr, Al, Li, Zn).

[0035] The surface of the metallic magnetic particles 10a made of the above-mentioned metallic magnetic material may be covered with an insulating film (not shown). Covering the surface of the metallic magnetic particles with an insulating film can increase the insulation between the metallic magnetic particles. Methods for forming the insulating film on the surface of the metallic magnetic particles include the sol-gel method and the mechanochemical method. The material constituting the insulating film may be an oxide such as P or Si. The insulating film may also be an oxide film formed by the oxidation of the surface of the metallic magnetic particles. The thickness of the insulating film is preferably 1 nm to 50 nm, more preferably 1 nm to 30 nm, and even more preferably 1 nm to 20 nm. For example, a cross-section obtained by polishing an inductor sample can be photographed with a scanning electron microscope (SEM), and the thickness of the insulating film covering the surface of the metallic magnetic particles can be measured from the obtained SEM image.

[0036] The average particle size of the metallic magnetic particles 10a in the magnetic layer S is preferably 1 μm to 30 μm, more preferably 1 μm to 20 μm, and even more preferably 1 μm to 10 μm. The average particle size of the metallic magnetic particles 10a in the magnetic layer can be measured by the procedure described below. A sample of the inductor is cut to obtain a sample cross-section. Specifically, a sample cross-section is obtained by cutting through the center of the body so as to be perpendicular to the mounting surface and end face of the body. Multiple areas (e.g., 5 areas) of the obtained cross-section (e.g., 130 μm × 100 μm) are photographed with an SEM, and the obtained SEM images are analyzed using image analysis software (e.g., image analysis software WinROOF2021 (manufactured by Mitani Corporation)) to determine the equivalent circle diameter of the metallic magnetic particles. The average value of the obtained equivalent circle diameters is taken as the average particle size of the metallic magnetic particles.

[0037] When forming the base body 10, heat treatment is applied. In this case, the metallic magnetic particles 10a contained in the base body 10 have an oxide film on their surface. This oxide film originates from the metallic magnetic particles 10a and is formed by the heat treatment. In the base body 10, adjacent metallic magnetic particles 10a are joined to each other via the oxide film.

[0038] The base body 10 may include a non-magnetic layer between the first coil 21 and the second coil 22. By providing a non-magnetic layer between the first coil 21 and the second coil 22, the insulation between the first coil 21 and the second coil 22 can be improved, and short circuits between them can be prevented.

[0039] The non-magnetic layer may contain glass ceramic material and non-magnetic ferrite material as non-magnetic materials. The non-magnetic layer may contain non-magnetic ferrite material as a non-magnetic material. As the non-magnetic ferrite material, a non-magnetic ferrite material having a composition in which Fe is 40 mol% to 49.5 mol% of the entire non-magnetic layer when converted to Fe2O3, Cu is 6 mol% to 12 mol% of the entire non-magnetic layer when converted to CuO, and the remainder is ZnO can be used. The non-magnetic material may contain Mn3O4, Co3O4, SnO2, Bi2O3, SiO2, etc. as additives as needed, and may contain trace amounts of unavoidable impurities. The non-magnetic layer preferably contains Zn-Cu ferrite.

[0040] The thickness of the non-magnetic layer can be measured using the following procedure. The inductor sample is placed vertically, and the area around the sample is encased in resin, ensuring that the LT surface is exposed. Polishing is completed using a polishing machine to a depth of approximately half the width of the sample, exposing a cross-section parallel to the LT surface. After polishing, the polished surface is processed using ion milling (Hitachi High-Tech Corporation IM4000 ion milling device) to remove any sagging of the internal conductor caused by polishing. The approximate center of the non-magnetic layer in the polished sample is photographed with an SEM, and the thickness of the approximate center of the non-magnetic layer is measured from the obtained SEM image and defined as the thickness of the non-magnetic layer.

[0041] The element 10 may include non-magnetic sections 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 sections are provided at least at one location between adjacent coil conductors among the first coil conductors 51 and the second coil conductors 52. By providing non-magnetic sections between adjacent coil conductors, it is possible to prevent magnetic flux from leaking between the coil conductors and reducing the inductance value.

[0042] The non-magnetic layer and the non-magnetic portion may have the same composition. For example, the non-magnetic layer and the non-magnetic portion may be composed of Zn-Cu ferrite.

[0043] Inside the base body 10 are a first coil 21 and a second coil 22. The first coil 21 and the second coil 22 may 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. The base body 10 may contain only two coils, including the first coil 21 and the second coil 22, or it may contain three or more coils, including the first coil 21 and the second coil 22.

[0044] -Coil 1- The first coil 21 includes a plurality of first coil conductors 51 in the stacking direction (e.g., the height direction T). Adjacent first coil conductors 51 are connected to each other via conductors. The first coil 21 may have 1.75 turns by including first coil conductors 51 formed in two different stacking groups in the stacking direction. The number of turns is not limited to 1.75 and may be 2 or more by stacking the first coil conductors 51 in the stacking direction.

[0045] The thickness of each of the first coil conductors 51 may be the same. Also, the thickness of the first coil conductor 51 may be the same as the thickness of the second coil conductor 52, which will be described later.

[0046] The first coil conductor 51 may be a metal conductor such as Ag, Cu, and / or Pd, as an example of its material. The first coil conductor 51 may be formed, for example, by printing a conductive paste onto the magnetic layer S described above.

[0047] -Coil 2- The second coil 22 includes a plurality of second coil conductors 52 in the stacking direction (e.g., the height direction T). Adjacent second coil conductors 52 are connected via conductors. The second coil 22 may have 1.75 turns by including second coil conductors 52 formed in two different stacking groups in the stacking direction. The number of turns is not limited to 1.75 as shown in the example. Second coil conductor 52The number of layers can be increased to, for example, two or more by stacking them in the stacking direction. Also, the number of layers of the second coil conductor 52 may be the same as or different from the number of layers of the first coil conductor 51.

[0048] The thickness of each second coil conductor 52 may be the same. Also, the thickness of the second coil conductor 52 may be the same as the thickness of the first coil conductor 51.

[0049] The second coil conductor 52 may be a metal conductor such as Ag, Cu, and / or Pd, as an example of its material. Furthermore, the material of the second coil conductor 52 may be the same as that of the first coil conductor 51, or a different material may be used. The second coil conductor 52 may be formed, for example, by printing a conductive paste onto the magnetic layer S described above.

[0050] -Coil conductor connection section- The coil conductor 50 includes a coil conductor connection portion 50v. The coil conductor connection portion 50v includes a first coil conductor connection portion 51v, a second coil conductor connection portion 52v, a third coil conductor connection portion 53v, and a fourth coil conductor connection portion 54v. 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 located inside the base body 10. 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 exposed from the mounting surface (first main surface 11) of the base body 10.

[0051] The coil conductor connection portion 50v may be made of a metal conductor such as Ag, Cu, and / or Pd, as an example of its material. Furthermore, the material of the coil conductor connection portion 50v may be the same as that of the first coil conductor 51 and / or the second coil conductor 52, or a different material may be used. The coil conductor connection portion 50v may be formed, for example, by forming through holes in the magnetic layer S described above and printing conductive paste into the through holes.

[0052] The first coil conductor connection portion 51v connects the end of the first coil conductor 51 closest to the bottom surface (first main surface 11) of the base body 10 with the first external terminal 31. The first coil conductor connection portion 51v may extend along the stacking direction (for example, the height direction T). The first coil conductor connection portion 51v may have a stacked structure.

[0053] The second coil conductor connection portion 52v connects the other end of the first coil 21 to the second external terminal 32. The second coil conductor connection portion 52v may extend along the stacking direction (e.g., the height direction T). The second coil conductor connection portion 52v may have a stacked structure.

[0054] The third coil conductor connection portion 53v connects the end of the second coil conductor 52 closest to the bottom surface (first main surface 11) of the base body 10 with the third external terminal 33. The third coil conductor connection portion 53v may extend along the stacking direction (for example, the height direction T). The third coil conductor connection portion 53v may have a stacked structure.

[0055] The fourth coil conductor connection portion 54v connects the other end of the second coil 22 to the fourth external terminal 34. The fourth coil conductor connection portion 54v may extend along the stacking direction (e.g., the height direction T). The fourth coil conductor connection portion 54v may have a stacked structure.

[0056] Here, a suitable arrangement of the coil conductor connection portion 50v is such that 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 that constitutes the outer edge of the base 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 base body 10 in a plan view 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.

[0057] -External terminals- As shown in Figure 2, the external terminals 30 include 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 provided on the first main surface 11 of the base body 10 and are electrically connected to the first coil 21. The third external terminal 33 and the fourth external terminal 34 are provided on the first main surface 11 of the base body 10 and are electrically connected to the second coil 22. In the inductor 1, the first main surface 11 of the base body 10 can be used as the mounting surface.

[0058] The first external terminal 31 acts 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 base body 10, or it may be provided spanning the first main surface 11 and at least one of the first end surface 13 and the second side surface 16 of the base body 10.

[0059] The second external terminal 32 acts 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 base body 10, or it may be provided spanning the first main surface 11 and at least one of the second end surface 14 and the second side surface 16 of the base body 10.

[0060] The third external terminal 33 acts 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 base body 10, or it may be provided spanning the first main surface 11 and at least one of the second end surface 14 and the first side surface 15 of the base body 10.

[0061] The fourth external terminal 34 acts as an input electrode for the second coil 22. The fourth external terminal 34 may be provided only on the first main surface 11 of the base body 10, or it may be provided spanning the first main surface 11 and at least one of the first end surface 13 and the first side surface 15 of the base body 10.

[0062] The external terminal 30 has a coil conductor connection region CL located on the exposed region (the region where the coil conductor connection portion 50v is exposed) where the coil conductor 50 is exposed from the base body 10 in a planar perspective view from the mounting surface side of the base body 10, and an overlap region OL that overlaps with the base body 10. In other words, in a planar perspective view from the mounting surface side of the base body 10, the planar area of ​​the external terminal 30 is larger than the planar area of ​​the coil conductor connection portion 50v. By making the planar area of ​​the external terminal 30 relatively large, when mounting the inductor 1 on a mounting board or the like, it is possible to easily align the electrodes of the mounting board with the external terminal 30 of the inductor 1.

[0063] The external terminal 30 may be made of various materials, such as Cu or Ni, as an example. The external terminal 30 may be formed as a single layer or as a laminated structure of two or more layers. The external terminal 30 may be formed by any method, but as an example, it may be formed by plating (for example, electroless plating). When the external terminal 30 is formed by plating, the plating formation mechanism for the coil conductor connection portion 50v and the plating formation mechanism for the base body 10 containing the metallic magnetic particles 10a are different. Therefore, in the inductor 1 according to this embodiment, the average length of contact between the metallic magnetic particles 10a and the external terminal 30 is 10% or less, preferably 8% or less, more preferably 4% or less, and even more preferably 0% of the length of the overlap region OL of the external terminal 30 in the cross-section obtained by cutting the base body 10 in the height direction along the length direction of the base body 10 at a position passing through the external terminal 30 from the mounting surface (first main surface 11) side of the base body 10 (see Figure 4). The method for calculating the "average length of contact between the metallic magnetic particles and the external terminals" described herein will be explained in detail in the examples below.

[0064] Here, we will describe the specific plating formation mechanism in detail. As an example, if the metal magnetic particles 10a are Fe, the coil conductor connection part 50v is Ag, and the external terminal 30 is Cu, the ionization tendency of the metal magnetic particles (Fe) is greater than that of the coil conductor connection part (Ag), and the plating growth reaction will preferentially start on the side of the metal magnetic particles with the greater ionization tendency. Therefore, in conventional inductors where the external terminal is in contact with a substrate containing metal magnetic powder, and the planar area of ​​the external terminal is larger than the planar area of ​​the coil conductor connection part when viewed from the mounting surface side of the substrate 10, abnormalities in the formation of the external terminal occurred due to plating growth caused by the metal magnetic particles.

[0065] However, according to the inductor 1 of this embodiment, the average length of contact between the metal magnetic particles 10a and the external terminal 30 is 10% or less of the length of the overlap region OL (see Figure 4), so that plating growth caused by the metal magnetic particles 10a can be reduced. Therefore, abnormal formation of the external terminal 30 can be reduced.

[0066] As an example of a method to ensure that the average length of contact between the metallic magnetic particles 10a and the external terminals 30 is 10% or less of the length of the overlap region OL, this can be achieved by removing the metallic magnetic particles 10a from the mounting surface (first main surface 11) of the base body 10. With such a configuration, since the metallic magnetic particles 10a are removed from the mounting surface of the base body 10, the proportion of metallic magnetic particles 10a on the mounting surface can be further reduced, and contact between the metallic magnetic particles 10a and the external terminals 30 can be further reduced.

[0067] Furthermore, the detachment of the metallic magnetic particles 10a is not limited to the mounting surface of the base body 10, but may also occur on surfaces other than the mounting surface of the base body 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). With this configuration, since unintended metallic magnetic particles 10a around the base body 10 are removed, the formation of plating caused by these metallic magnetic particles 10a can be reduced.

[0068] Regarding the detachment of metallic magnetic particles 10a, the surface roughness of the mounting surface (first main surface 11) of the base body 10 is greater than the surface roughness of the surface opposite to the mounting surface (second main surface 12) of the base body 10. In this specification, surface roughness can be measured by the following method.

[0069] (1) A cross-section is created by cutting parallel to the height direction T (see Figure 1) of the base body 10 from the mounting surface side, along a virtual line extending in the length direction L of the base body, passing through the external terminals and coil conductor connection area on the mounting surface of the base body 10. Three such cross-sections are created along the width direction W (see Figure 1) of the base body. (2) At those cross-sections, on the first main surface of the body 10, three imaging locations are taken at 5000x magnification using an SEM (manufacturer: JEOL Ltd., Schottky field emission scanning electron microscope, model number JSM-7900F) and an EDX (manufacturer: JEOL Ltd., Schottky field emission scanning electron microscope, model number JSM-7900F). These locations are the parts on both sides of the coil conductor connection area of ​​the external terminal 30 on the first main surface of the body 10 that extend outward from the coil conductor connection area and are in contact with the body 10, specifically the center and both ends of the external terminal that has a longer distance from the coil conductor connection area to the tip, and three imaging locations on the second main surface 12 of the body 10 that correspond to these imaging locations. (3) In each captured field of view, the positional relationship of the metal magnetic particles in the SEM can be confirmed by checking the position of the metal magnetic particles 10a (e.g., Fe) contained in the element 10 and the composition of the external terminal 30 (e.g., Cu) using EDX. Next, the SEM images are loaded into the image analysis software "Win RooF" (manufactured by Mitani Corporation), and the outer edge of the metal magnetic particle on the surface side of the metal magnetic particle is identified in the SEM image based on the composition image of the metal magnetic particle from the EDX (for example, the Fe composition image). Then, tangents are drawn between the outer edges of the metal magnetic particles that are closest to the surface of the substrate and the outer edges of the metal magnetic particles that are second closest to the surface of the substrate within the field of view, and the distance between the outer edge of the metal magnetic particle that is most recessed inward into the substrate and the tangent is measured. By performing this measurement on the first main surface 11 and the second main surface 12 of the substrate 10, it is possible to measure the surface roughness of the first main surface 11 and the surface roughness (maximum unevenness) of the second main surface 12.

[0070] In a preferred configuration of the external terminal 30, the external terminal 30 may be embedded in the recesses where the metallic magnetic particles 10a have been removed from the mounting surface (first main surface 11) of the base body 10. With such a configuration, the external terminal 30, by embedding itself in the recesses where the metallic magnetic particles 10a have been removed, exerts an anchoring effect, thereby improving the adhesion between the base body 10 and the external terminal 30.

[0071] -Insulating layer- The insulating layer 70 covers the surface of the base body 10, excluding the external terminals 30, on the mounting surface (first main surface 11). Specifically, it is a layer laminated on the first main surface 11 of the base body 10 (see Figures 1-4), and photoresist is one example. In this way, by providing the insulating layer 70 in the inductor 1 of this embodiment, it is possible to prevent short circuits between the inductor 1 and the mounting substrate on which the inductor 1 is mounted.

[0072] Furthermore, in a preferred configuration of the insulating layer 70, the insulating layer 70 may be embedded in the recesses where the metallic magnetic particles 10a have fallen off on the mounting surface (first main surface 11) of the base body 10 (see Figure 4). With such a configuration, the insulating layer 70 embeds itself in the recesses where the metallic magnetic particles 10a have fallen off, exerting an anchoring effect, thereby improving the adhesion between the base body 10 and the insulating layer 70.

[0073] <Inductor of the second embodiment> Next, the inductor of the second embodiment will be described with reference to Figures 5 to 8. Figure 5 is an exploded perspective view of the inductor of the second embodiment, Figure 6 is a cross-sectional view in the direction of the arrow VI-VI in Figure 5, Figure 7 is an enlarged cross-sectional view of the main part of Figure 6, and Figure 8 is an enlarged cross-sectional view of the main part of an inductor of a modified example of the second embodiment. The inductor of the second embodiment differs from the inductor of the first embodiment described above in its configuration of external terminals. The following description will focus on the differences from the inductor described in the above embodiment.

[0074] The inductor 1 of this embodiment comprises a base body 10 containing a coil conductor 50 and metallic magnetic particles 10a, a coil conductor connection portion 50v that is electrically connected to the coil conductor 50 and exposed from the base body 10, and an external terminal 30 provided on the mounting surface (first main surface 11) of the base body 10 and electrically connected to the coil conductor connection portion 50v. In a planar perspective view of the base body 10 from the mounting surface side, the external terminal 30 is positioned inside the exposed region E where the coil conductor connection portion 50v is exposed from the base body 10 (see Figures 6 and 7).

[0075] More specifically, unlike the first embodiment, the inductor 1 of this embodiment has a planar view from the mounting side of the base body 10, in which 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 planar view from the mounting side of the base body 10, there is no overlapping region where the external terminal 30 and the base body 10 overlap. However, the inductor of the first embodiment and the inductor of the second embodiment share a common technical concept in that they both have the technical concept of "preventing plating growth caused by metal magnetic particles contained in the base body."

[0076] In other words, in the second embodiment, the inductor 1, when viewed from the mounting side of the base body 10 in a planar perspective view, has the external terminal 30 positioned inside the exposed region E where the coil conductor connection portion 50v is exposed from the base body 10, and the base body 10 and the external terminal 30 are not in contact. Therefore, even if the external terminal 30 is formed by plating, abnormalities in the formation of the external terminal 30 can be reduced.

[0077] As a preferred embodiment of the inductor, the depth of the recess where the metal magnetic particles 10a have been removed may be greater than or equal to the maximum particle diameter of the metal magnetic particles 10a and less than or equal to twice the maximum particle diameter. The method for measuring the maximum particle diameter is the method described in <Inductor of the First Embodiment>. Specifically, a sample cross-section is obtained by cutting the body through its center so as to be perpendicular to the mounting surface and end face of the body. Multiple areas (e.g., 130 μm × 100 μm) of the obtained cross-section are photographed with an SEM at multiple locations (e.g., 5 locations), and the obtained SEM images are analyzed using image analysis software (e.g., image analysis software WinROOF2021 (manufactured by Mitani Corporation)) to determine the equivalent circular diameter of the metal magnetic particles. The maximum value of the obtained equivalent circular diameter is taken as the maximum particle size of the metal magnetic particles. With such a configuration, the thickness of the insulating layer 70 can be secured, thereby increasing the strength of the inductor. The specification regarding the depth of the recess where the particles have been removed may also be applied to the inductor according to the first embodiment.

[0078] <Manufacturing method for the inductor of the first embodiment> The manufacturing method of the "Inductor of the First Embodiment" will be described with reference to Figure 10. Figure 10 is a flowchart showing the manufacturing method of the inductor of this disclosure. The manufacturing method of the inductor of the first embodiment may include a base body formation step, an exposure step, a degranulation step, an external terminal formation step, and an insulating layer formation step. The steps will be described in detail below.

[0079] -Body formation process- The base body formation process includes a laminate formation process for forming a laminate that constitutes the base body 10, and a firing process for firing the laminate.

[0080] • Lamination process First, the magnetic layer S described in Figure 2 is prepared. The magnetic layer S is prepared by printing and layering a magnetic paste containing metallic magnetic particles 10a with an average particle size of preferably 1 μm to 30 μm, more preferably 1 μm to 20 μm, and even more preferably 1 μm to 10 μm.

[0081] Next, conductive paste that will become the coil conductor 50 is printed onto the prepared magnetic layer S, conductive paste that will become the conductor layer (or via conductor) connecting the coil conductors 50 is printed, conductive paste that will become the coil conductor connection part 50v is printed, and magnetic paste is printed on the parts other than the coil conductor, conductor layer, and coil conductor connection part. This prepares the laminated groups G1 to G7 as described in Figure 2. Then, the prepared laminated groups G1 to G7 are laminated and crimped together to form a laminated body.

[0082] • Firing process The formed laminate is degreased to remove the binders contained in the magnetic paste and conductive paste, and then fired. The firing temperature is such that the laminate hardens, for example, it may be around 700°C. Furthermore, in order to increase the strength of the laminate, the laminate is impregnated with resin and cured. The resin used to impregnate the laminate is epoxy resin, but one or more resins selected from the group consisting of phenolic resin, polyester resin, polyimide resin, polyolefin resin, silicone resin, acrylic resin, polyvinyl butyral resin, cellulose resin, and alkyd resin may also be used. Through the above process, a base body 10 is formed which contains a coil conductor 50 inside and contains metallic magnetic particles 10a and resin.

[0083] -Exposure process- The exposure process is a process of exposing the coil conductor connection portion 50v, which is electrically connected to the coil conductor 50, from the base body 10. Specifically, the coil conductor connection portion 50v is exposed from the base body 10 by grinding the first main surface 11 of the base body 10, thereby ensuring electrical connectivity with the external terminal 30 described later. In other words, on the mounting surface side of the laminate, the coil conductor connection portion 50v is exposed by removing the resin impregnated into the laminate as described above. Note that this grinding is performed on the second main surface 12, first end surface 13, second end surface 14, first side surface 15 and / or second side surface of the base body 10 in order to shape the base body 10. 16This may also be performed on the base body 10. Here, the exposure process is not limited to grinding, but any method can be used as long as it can expose the coil conductor connection portion 50v from the base body 10. For example, the coil conductor connection portion 50v may be exposed from the base body 10 by chemical etching.

[0084] -Shelling process- The degranulation process is a process of degranulating the metallic magnetic particles 10a from the mounting surface (first main surface 11) of the base body 10. Specifically, the metallic magnetic particles 10a are removed from the mounting surface (first main surface 11) of the base body 10 by immersing the base body 10 containing the metallic magnetic particles 10a in an acidic solution. Sulfuric acid is an example of an acidic solution used to remove the metallic magnetic particles 10a. After degranulating the metallic magnetic particles 10a by immersion in an acidic solution, a thin resin film may be formed on the affected area, or an oxide film may be formed by oxidation treatment.

[0085] -Insulating layer formation process- The insulating layer formation step is a step of forming an insulating layer 70 on the mounting surface (first main surface 11) of the base body 10, excluding at least the position where the coil conductor connection portion 50v is exposed from the base body 10. Specifically, the insulating layer 70 may be, for example, a photosensitive resist resin containing silica as a filler. The resist resin is applied to the entire mounting surface of the base body 10 by screen printing or the like. After pattern exposure is performed on the photosensitive resist resin applied to the entire mounting surface along the shape of the external terminals 30 described later, it is immersed in a developing solution to remove the insulating layer 70 in the areas where the external terminals 30 are formed. Here, when manufacturing the inductor of the first embodiment, the insulating layer 70 is formed such that the external terminals 30 have an overlapping region that overlaps with the base body 10 in a planar perspective view as seen from the mounting surface side of the base body 10. Although the above-described insulating layer formation step uses a photosensitive resist resin, an insulating layer formation method other than screen printing may be used, such as attaching a resist film to the mounting surface of the base body 10.

[0086] -External terminal formation process- The external terminal formation process involves forming external terminals at locations where metal magnetic particles have been removed and at locations where the coil conductor connection portion is exposed from the base body. Specifically, a Pd catalyst is applied to the area on the mounting surface (first main surface 11) of the base body 10 where the insulating layer 70 has been removed, and external terminals are formed by electroless plating. The plating configuration involves forming Cu plating at the coil conductor connection portion. Other examples include, but are not limited to, Ni-Sn, Ni-Au, Ni-Cu, Cu-Ni-Au, etc. After external terminal formation, the element can be cut into individual components to manufacture the inductor of this embodiment.

[0087] As described above, according to the inductor manufacturing method described in this embodiment, metallic magnetic particles are removed from the mounting surface of the base body, and external terminals are formed at the locations where the metallic magnetic particles have been removed and at the locations where the coil conductor connection portion is exposed from the base body. Therefore, plating growth caused by metallic magnetic particles can be reduced. Consequently, abnormalities in the formation of external terminals can be reduced.

[0088] <Manufacturing method for the inductor according to the second embodiment> The manufacturing method for the "inductor of the second embodiment" will now be described. Note that the body formation process, exposure process, and degraining process in the manufacturing method of the inductor of the second embodiment are substantially the same as those in the manufacturing method of the inductor of the first embodiment, and therefore their explanation will be omitted. The following description will focus on the differences from the manufacturing method of the inductor of the first embodiment described above.

[0089] -Insulating layer formation process- In the insulating layer formation step of the inductor manufacturing method of the second embodiment, the insulating layer 70 is formed such that, in a planar view from the mounting side of the base body 10, the external terminal 30 is positioned inside the exposed region E where the coil conductor connection portion 50v is exposed from the base body 10. In other words, in a planar view from the mounting side of the base body 10, the insulating layer 70 is formed so as to cover a part of the coil conductor connection portion 50v.

[0090] -External terminal formation process- The external terminal formation process involves forming the external terminal 30 inside the exposed region E (see Figures 6 and 7) where the coil conductor connection portion 50v is exposed from the base body 10. In other words, the external terminal 30 is formed so as not to come into contact with the base body 10, but only with the coil conductor connection portion 50v.

[0091] As described above, according to the inductor manufacturing method described in this embodiment, in a planar perspective view from the mounting surface side of the base body 10, the external terminal 30 is positioned inside the exposed region E where the coil conductor connection portion 50v is exposed from the base body 10, and the base body 10 and the external terminal 30 are not in contact. Therefore, even if the external terminal 30 is formed by plating, abnormalities in the formation of the external terminal 30 can be reduced. [Examples]

[0092] This disclosure details the demonstration tests conducted on the inductor described herein.

[0093] <Verification Test 1: Composition Analysis> The following examples and comparative examples were subjected to compositional analysis using EDX.

[0094] • Examples The inductor of the first embodiment shown in Figure 4 was used, and the grain removal process shown in Figure 10 was performed. • Comparative Example An inductor that has not undergone the grain removal process shown in Figure 10.

[0095] Compositional analysis using EDX was performed using an EDX machine (manufacturer: JEOL Ltd., model number: JSM-7900F), and the observation conditions for compositional analysis were set to an observation magnification of 5000x.

[0096] The compositional analysis results are shown in Figure 11. According to the compositional analysis results in Figure 11, in the inductor of the example, Fe elements were detected at the locations where metallic magnetic particles were contained in the base material, and it was confirmed that the elements constituting the plating components as external terminals (e.g., Cu elements) had entered the recessed areas in the base material where the particles had been removed. On the other hand, in the inductor of the comparative example, the boundary between the Fe elements as metallic magnetic particles and the elements constituting the plating components as external terminals (e.g., Cu elements) was clearly separated, and it was confirmed that the external terminals had not entered the base material.

[0097] <Verification Test 2: SEM Observation 1> SEM observation was performed on the inductors of the above-described embodiment and comparative example. SEM observation was performed using an SEM (manufacturer: JEOL Ltd., model number: JSM-7900F), and the observation conditions were set to two magnification levels: 1500x and 5000x.

[0098] A schematic diagram of the SEM image is shown in Figure 12. The schematic diagram in Figure 12 shows the vicinity of the boundary between the substrate containing the metallic magnetic particles and the insulating layer. According to Figure 12, it was possible to confirm that the insulating layer in the inductor of the example had penetrated into the recesses where the metallic magnetic particles had fallen out. In particular, by magnifying up to 5000 times, it was clearly confirmed that the insulating layer had penetrated into the substrate. On the other hand, in the inductor of the comparative example, the boundary between the insulating layer and the substrate was clearly separated, and the insulating layer had not penetrated into the substrate.

[0099] <Verification Test 3: SEM Observation 2> In demonstration test 3, SEM observations were performed on the examples and comparative examples to check for abnormal plating growth. The observation conditions were set to approximately 500x magnification.

[0100] A schematic diagram of the SEM image is shown in Figure 13. In the comparative example inductor, the average length of contact between the metal magnetic particles and the external terminal exceeds 10% of the length of the overlap region. Therefore, the influence of the metal magnetic particles 10a exposed on the surface of the base body is significant, and because the plating formation mechanism for the base body 10 containing the metal magnetic particles 10a is different from the plating formation mechanism for the coil conductor connection portion 50v, abnormal plating growth occurs on the base body side at the external terminal. In this specification, "abnormal plating growth" means that the average thickness of the plating on the base body is 20% or more thicker than the average thickness of the plating on the coil conductor connection region. On the other hand, in the example inductor, as will be explained in the demonstration test 4 described later, in the overlap region where the external terminal and the base body overlap in a planar perspective view from the mounting surface side of the base body, the average length of contact between the metal magnetic particles and the external terminal is 10% or less of the length of the overlap region. Therefore, it was confirmed that abnormal plating growth like that of the comparative example inductor did not occur.

[0101] <Verification Test 4: SEM Observation 3> In demonstration test 4, the contact ratio between the metallic magnetic particles and the external terminals was calculated for the example using SEM observation. The calculation method is described in detail below.

[0102] (1) A cross-section is created by cutting parallel to the height direction T (see Figure 1) of the base body 10, from the mounting surface (first main surface 11) side, along a virtual line extending in the length direction L of the base body, passing through the external terminals and coil conductor connection area of ​​the mounting surface of the base body 10. Three such cross-sections are created along the width direction W (see Figure 1) of the base body. (2) At each cross-section, for each external terminal 30 on the first main surface of the body 10, three locations are photographed at a magnification of 5000x using an SEM (manufacturer: JEOL Ltd., model number: JSM-7900F) and an EDX (manufacturer: JEOL Ltd., model number: JSM-7900F) at the center and both ends of the external terminal that has the longer distance from the coil conductor connection area to the tip, among the portions that extend outward from the coil conductor connection area on both sides of the coil conductor connection area of ​​the external terminal 30 and are in contact with the body 10. (3) In each captured field of view, the composition of the metal magnetic particles 10a constituting the base body 10 (e.g., Fe), the composition of the resin in the base body (e.g., C), and the composition of the external terminals (Cu) are confirmed using EDX, and the positional relationship between the metal magnetic particles, the base body, and the external terminals is confirmed. Next, the SEM image is loaded into the image analysis software "Win RooF" (manufactured by Mitani Corporation), and the outer edge of the external terminal is identified in the SEM image based on the composition image of the EDX external terminal (for example, the Cu composition image) (see the SEM image after image processing in Figure 14). Then, the length of the outer edge on the metallic magnetic particle side of the external terminal is calculated using image processing. Next, based on the compositional images of the EDX metal magnetic particles (e.g., Fe compositional image) and the resin (e.g., C compositional image), the outer edges of the metal magnetic particles that are in contact with the external terminals and where no resin is present around the metal magnetic particles are identified by image processing. Then, for each external terminal, the ratio of the contact length between the metal magnetic particle and the external terminal to the length of the outer edge of the metal magnetic particle side of the external terminal was calculated for each of the multiple fields of view captured, and the average of these ratios was calculated for all external terminals to obtain the contact ratio shown in Figure 14.

[0103] Figure 14 shows the results of calculating the contact ratio between the metallic magnetic particles and the external terminals. It was confirmed that the contact ratio was 10% or less at all three shooting locations in the width direction of the base body (position 1: 4%, position 2: 0%, position 3: 8%). Furthermore, no abnormal plating growth, as explained in demonstration test 3, was observed at any of the three locations.

[0104] As described above, the inductor and the method for manufacturing an inductor according to this disclosure make it possible to reduce abnormalities in the formation of external terminals and improve the yield of inductors.

[0105] It should be noted that the embodiments disclosed herein are illustrative in all respects and do not constitute a basis for limiting interpretation. For example, the embodiments described above disclose a coil constructed by stacking coil conductors, but the invention is not limited to this coil, and a coil constructed by winding a wire may also be disclosed. More specifically, an air-core coil may be constructed by winding a wire in a spiral pattern in two stages such that the lead-out portions of the wire are located on the outer circumference, and the coil may be embedded so that the winding axis is perpendicular to the mounting surface of the base body.

[0106] Furthermore, in the inductor of the first embodiment and the inductor of the second embodiment, the basic body 10 and external terminals 30 may be replaced with the configurations shown in Figures 15 to 17. The configurations of the basic body 10 and external terminals 30 will be described in detail below.

[0107] -Base model- The base body 10 shown in Figure 15 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 on the second main surface 12. The third external terminal 33 and the fourth external terminal 34 are arranged along the long side (or short side) of the second main surface 12.

[0108] Furthermore, the base body 10 shown in Figure 15 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. 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.

[0109] The base body 10 shown in Figure 15 may be constructed by stacking the stacking groups G1 to G9 shown in Figure 16. The stacking groups G1 to G9 will be described in detail below, but elements common to both Figure 2 and the above-mentioned figures will be given the same reference numerals, and explanations will be omitted as appropriate.

[0110] The laminated group G1 constitutes the second main surface 12 of the base body 10. The third external terminal 33 and the fourth external terminal 34 are arranged along the long side (or short side) of the second main surface 12.

[0111] In the laminated group G2, the third coil conductor connection portion 53v and the fourth coil conductor connection portion 54v are arranged in accordance with the arrangement of the third external terminal 33 and the fourth external terminal 34.

[0112] The second coil conductor 52 is arranged such that the second coil 22 is formed by laminated group G3 and laminated group G4.

[0113] The laminated group G5 has a magnetic layer S arranged to electrically insulate the first coil 21 and the second coil 22.

[0114] The first coil conductor 51 is arranged such that the first coil 21 is composed of laminated groups G6 and G7.

[0115] In the stacked group G8, the first coil conductor connection portion 51v and the second coil conductor connection portion 52v are arranged in accordance with the arrangement of the first external terminal 31 and the second external terminal 32.

[0116] The laminated group G9 constitutes the first main surface 11 of the base body 10. The first external terminal 31 and Second external terminal 32 It is positioned there.

[0117] Furthermore, the insulating layer 70 covers the mounting surfaces (first main surface 11 and second main surface 12) of the base body 10, excluding the external terminals 30.

[0118] In the inductor described above, as explained in the inductor of the first embodiment, the overlap region OL of the external terminal 30 is in the cross-section obtained by cutting the body 10 in the height direction along the length direction of the body 10 at a position passing through the coil conductor connection region CL from the mounting surface (first main surface 11 and / or second main surface 12) side of the body 10, along the length direction of the body 10. of In relation to the length, the metal magnetic particle 10a and the external terminal 30 are in contact. averageThe length is 10% or less. Therefore, plating growth caused by metallic magnetic particles can be reduced, and abnormalities in the formation of external terminals can be reduced.

[0119] Furthermore, in the inductor described above, as explained in the inductor of the second embodiment, the external terminals may be positioned inside the exposed region where the coil conductor is exposed from the base body in a planar perspective view from the mounting surface side of the base body. With such an inductor of the second embodiment, contact between the metal magnetic particles and the external terminals can be prevented, and abnormalities in the formation of the external terminals can be reduced.

[0120] Furthermore, in the inductor of the first embodiment and the inductor of the second embodiment, the basic body 10 and external terminals 30 may be replaced with the configurations shown in Figures 18-19. The configurations of the basic body 10 and external terminals 30 will be described in detail below.

[0121] -Base model- The base body 10 shown in Figure 18 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 the second main surface 12. The first external terminal 31 and the fourth external terminal 34 are located diagonally opposite each other on the second main surface 12.

[0122] Furthermore, the base body 10 shown in Figure 18 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 the first main surface 11. The second external terminal 32 and the third external terminal 33 are located on the diagonal of the first main surface 11 (a diagonal different from the diagonal of the second main surface 12).

[0123] The base body 10 shown in Figure 18 may be constructed by stacking the stacking groups G1 to G9 shown in Figure 19. The stacking groups G1 to G9 will be described in detail below, but elements common to Figures 2 or 16 will be given the same reference numerals, and explanations will be omitted as appropriate.

[0124] The laminated group G1 constitutes the second main surface 12 of the base body 10. The first external terminal 31 and the fourth external terminal 34 are arranged on the diagonal of the second main surface 12.

[0125] In the laminated group G2, the first coil conductor connection part 51v and the fourth coil conductor connection part 54v are arranged in accordance with the arrangement of the first external terminal 31 and the fourth external terminal 34.

[0126] In parts of lamination groups G3, G5, and G7, first coil conductors 51 are arranged to form a first coil 21. More specifically, in lamination group G3, the first coil conductors 51 are arranged along two sides of the magnetic layer S that constitute the corner corresponding to the second external terminal 32 in a planar view; in lamination group G5, the first coil conductors 51 are arranged along three sides of the 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 in a planar view; and in lamination group G7, the first coil conductors 51 are arranged along three sides of the 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 in a planar view. Each of the first coil conductors 51 is electrically connected to another by via conductors V.

[0127] Furthermore, in parts of lamination groups G3, G5, and G7, second coil conductors 52 are arranged so as to constitute a second coil 22. More specifically, in lamination group G3, the second coil conductors 52 are arranged along two sides of the magnetic layer S that constitute the corner corresponding to the third external terminal 33 in a planar view; in lamination group G5, the second coil conductors 52 are arranged along three sides of the 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 in a planar view; and in lamination group G7, the second coil conductors 52 are arranged along three sides of the 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 in a planar view. Each second coil conductor 52 is electrically connected to the others by via conductors V.

[0128] To rephrase the arrangement of the first coil conductor 51 and the second coil conductor 52 described above, the first coil conductor 51 and the second coil conductor 52 may be point-symmetrical with respect to the center of each laminated group G3, G5, and G7.

[0129] In the laminated group G8, the second coil conductor connection portion 52v and the third coil conductor connection portion 53v are arranged in accordance with the arrangement of the second external terminal 32 and the third external terminal 33.

[0130] The laminated group G9 constitutes the first main surface 11 of the base body 10. The second external terminal 32 and the third external terminal 33 are arranged diagonally across the first main surface 11.

[0131] Furthermore, the insulating layer 70 covers the mounting surfaces (first main surface 11 and second main surface 12) of the base body 10, excluding the external terminals 30.

[0132] In the inductor described above, as explained in the inductor of the first embodiment, the overlap region OL of the external terminal 30 is in the cross-section obtained by cutting the body 10 in the height direction along the length direction of the body 10 at a position passing through the coil conductor connection region CL from the mounting surface (first main surface 11 and / or second main surface 12) side of the body 10, along the length direction of the body 10. of In relation to the length, the metal magnetic particle 10a and the external terminal 30 are in contact. average The length is 10% or less. Therefore, plating growth caused by metallic magnetic particles can be reduced, and abnormalities in the formation of external terminals can be reduced.

[0133] Furthermore, in the inductor described above, as explained in the inductor of the second embodiment, the external terminals may be positioned inside the exposed region where the coil conductor is exposed from the base body in a planar perspective view from the mounting surface side of the base body. With such an inductor of the second embodiment, contact between the metal magnetic particles and the external terminals can be prevented, and abnormalities in the formation of the external terminals can be reduced.

[0134] Furthermore, the technical scope of the present invention is not construed solely by the embodiments described above, but is defined based on the claims. The technical scope of the present invention also includes all modifications within the meaning and scope of the claims.

[0135] The inductors and methods for manufacturing inductors described herein include the following embodiments. <1> A base body containing a coil conductor, metallic magnetic particles, and resin, The above-mentioned body is provided with an external terminal on its mounting surface that is electrically connected to the coil conductor, The aforementioned body has a first principal surface and a second principal surface that are opposite to each other in the height direction, a first end surface and a second end surface that are perpendicular to the height direction and opposite to each other in the length direction, and a first side surface and a second side surface that are perpendicular to the length direction and the height direction and opposite to each other in the width direction, The external terminal has a coil conductor connection region located on an exposed region where the coil conductor is exposed from the base body in a planar perspective view from the mounting surface side of the base body, and an overlapping region that overlaps with the base body. An inductor in which the average length of contact between the metal magnetic particles and the external terminals is 10% or less of the length of the overlap region of the external terminals in a cross-section obtained by cutting the body in the height direction along the length direction of the body from the mounting surface side of the body at a position passing through the connection area between the external terminals and the coil conductor. <2> A base body containing a coil conductor inside, metal magnetic particles, and resin, The above-mentioned body is provided with an external terminal on its mounting surface that is electrically connected to the coil conductor, An inductor in which, in a planar perspective view from the mounting surface side of the base body, the external terminals are arranged inside the exposed region where the coil conductor is exposed from the base body. <3> The metal magnetic particles are detached from the mounting surface of the substrate. <1> or <2> The inductor described above. <4> The metallic magnetic particles are detached from surfaces of the substrate other than the mounting surface. <1> ~ <3> An inductor listed in any one of the following. <5> The external terminals are positioned in the recesses where the metal magnetic particles have been removed from the mounting surface of the aforementioned body. <1> Quote and <2> Do not quote, <1> , <3> or <4> An inductor listed in any one of the following. <6> The mounting surface of the base body is provided with an insulating layer that covers the surface excluding the surface that comes into contact with the external terminals. <1> ~ <5> An inductor listed in any one of the following. <7> The insulating layer is formed in the recesses where the metal magnetic particles have fallen off on the mounting surface of the base body. <6> The inductor described above. <8> The depth of the recess where the metal magnetic particles have been removed is greater than or equal to the maximum particle diameter of the metal magnetic particles and less than or equal to twice the maximum particle diameter. <1> ~ <7> An inductor listed in any one of the following. <9> A process for forming a substrate that has a coil conductor inside and contains metal magnetic particles and resin, An exposure step in which the external terminal connection area of ​​the coil conductor is exposed from the base body, A degranulation step in which the metal magnetic particles are removed from the mounting surface of the base body, An external terminal forming step is performed to form external terminals at the locations where the metal magnetic particles have been removed by the aforementioned degranulation step and at the locations of the external terminal connection region of the coil conductor that have been exposed by the aforementioned exposure step. A method for manufacturing an inductor, which includes the following features. <10> A process for forming a substrate that has a coil conductor inside and contains metal magnetic particles and resin, An exposure step in which the external terminal connection area of ​​the coil conductor is exposed from the base body, An external terminal forming step is performed to form an external terminal inside the exposed region where the external terminal connection region of the coil conductor is exposed from the base body, A method for manufacturing an inductor, which includes the following features. <11> The process includes an insulating layer forming step in which an insulating layer is formed on the surface of the mounting surface of the base body, excluding the surface that comes into contact with the external terminals. <9> or <10> The method for manufacturing an inductor as described above. <12> The aforementioned body formation step is, A step of forming a laminate by stacking the coil conductor and the magnetic layer containing the metallic magnetic particles, A firing process for firing the laminate, Equipped with, <9> ~ <11> A method for manufacturing an inductor as described in any one of the following. <13> The exposure process is performed by grinding the mounting surface of the base body. <9> ~ <12> A method for manufacturing an inductor as described in any one of the following. <14> The aforementioned threshing process is carried out by etching with an acidic solution. <9> or <9> To quote <11> or <12> The method for manufacturing an inductor as described above. <15> The external terminal formation step is performed by electroless plating. <9> ~ <14> A method for manufacturing an inductor as described in any one of the following. [Industrial applicability]

[0136] This disclosure can be used in inductors that reduce abnormalities in the formation of external terminals. [Explanation of symbols]

[0137] 1 Inductor 10 Base Body 10a Metal magnetic particles 11. First Main Surface 12 Second Main Surface 13 First end surface 14 Second end face 15 First aspect 16 Second aspect 21. First coil 22 Second Coil 30 External terminals 31 First external terminal 32 Second external terminal 33 Third external terminal 34. Fourth external terminal 50 Coil Conductors 51 First coil conductor 52 Second coil conductor 50V coil conductor connection 51V First coil conductor connection 52V Second coil conductor connection 53V Third coil conductor connection 54V 4th coil conductor connection G1-G7 Lamination Group 70 Insulating layer S magnetic layer OL overlap region CL coil conductor connection area E exposed area

Claims

1. A base body containing a coil conductor, metallic magnetic particles, and resin, The above-mentioned body is provided with an external terminal on its mounting surface that is electrically connected to the coil conductor, The aforementioned body has a first main surface and a second main surface that are opposite to each other in the height direction, a first end surface and a second end surface that are perpendicular to the height direction and opposite to each other in the length direction, and a first side surface and a second side surface that are perpendicular to the length direction and the height direction and opposite to each other in the width direction, The external terminal has a coil conductor connection region located on an exposed region where the coil conductor is exposed from the base body in a planar perspective view from the mounting surface side of the base body, and an overlapping region that overlaps with the base body. An inductor in which, with respect to the length of the overlap region of the external terminals in a cross-section obtained by cutting the body in the height direction along the length direction of the body from the mounting surface side of the body at a position passing through the connection region between the external terminals and the coil conductor, the average length of contact between the metal magnetic particles and the external terminals is 10% or less.

2. A base body containing a coil conductor inside, metal magnetic particles, and resin, The above-mentioned body is provided with an external terminal on its mounting surface that is electrically connected to the coil conductor, An inductor in which, in a planar perspective view from the mounting surface side of the base body, the external terminals are arranged inside the exposed region where the coil conductor is exposed from the base body.

3. The inductor according to claim 1, wherein the metallic magnetic particles are detached from the mounting surface of the substrate.

4. The inductor according to claim 1, wherein the metallic magnetic particles are detached from a surface of the substrate other than the mounting surface.

5. The inductor according to claim 1, wherein the external terminals are fitted into recesses where the metal magnetic particles have been removed on the mounting surface of the base body.

6. The inductor according to claim 1, wherein the mounting surface of the base body is provided with an insulating layer that covers the surface excluding the surface that comes into contact with the external terminals.

7. The inductor according to claim 6, wherein the insulating layer is embedded in the recesses where the metal magnetic particles have fallen off on the mounting surface of the base body.

8. The inductor according to claim 1, wherein the depth of the recess where the metal magnetic particles have been removed is greater than or equal to the maximum particle diameter of the metal magnetic particles and less than or equal to twice the maximum particle diameter.

9. A process for forming a substrate that has a coil conductor inside and contains metal magnetic particles and resin, An exposure step in which the external terminal connection area of ​​the coil conductor is exposed from the base body, A degranulation step in which the metal magnetic particles are removed from the mounting surface of the base body, An external terminal forming step is performed to form external terminals at the locations where the metal magnetic particles have been removed by the aforementioned degranulation step and at the locations of the external terminal connection region of the coil conductor that have been exposed by the aforementioned exposure step. A method for manufacturing an inductor, which includes the following features.

10. A process for forming a substrate that has a coil conductor inside and contains metal magnetic particles and resin, An exposure step in which the external terminal connection area of ​​the coil conductor is exposed from the base body, An external terminal forming step is performed to form an external terminal inside the exposed region where the external terminal connection region of the coil conductor is exposed from the base body, A method for manufacturing an inductor, which includes the following features.

11. A method for manufacturing an inductor according to claim 9 or 10, comprising an insulating layer forming step of forming an insulating layer on the surface of the mounting surface of the base body, excluding the surface that comes into contact with the external terminals.

12. The aforementioned body formation step is, A step of forming a laminate by stacking the coil conductor and the magnetic layer containing the metallic magnetic particles, A firing process for firing the laminate, A method for manufacturing an inductor according to claim 9 or 10, comprising:

13. The method for manufacturing an inductor according to claim 9 or 10, wherein the exposure step is performed by grinding the mounting surface of the base body.

14. The method for manufacturing an inductor according to claim 9, wherein the grain removal step is performed by etching with an acidic solution.

15. The method for manufacturing an inductor according to claim 9, wherein the external terminal formation step is performed by electroless plating.

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