Laminated coil component

Abstract

The present invention provides a laminated coil component capable of reducing current density without significantly changing the external shape of a chip, the laminated coil component comprising: a laminated body in which a plurality of insulating layers are laminated and which has a coil therein; and first and second external electrodes electrically connected to the coil and forming the coil by electrically connecting a plurality of coil conductors stacked together with the insulating layer, the laminated body has first and second end surfaces facing each other in a longitudinal direction, first and second main surfaces facing each other in a height direction orthogonal to the longitudinal direction, and first and second side surfaces facing each other in a width direction orthogonal to the longitudinal direction and the height direction, and the first external electrode covers at least a part of the first end surface. The second external electrode covers at least a portion of the second end surface, a coil axis of the coil is parallel to the first main surface, a first recess having a deepest portion on an inner side of a surrounding shape of the coil when the laminated body is viewed in a longitudinal direction is provided on the first end surface, and the first external electrode covers at least a portion of the first recess.

Description

Technical Field

[0001] The present invention relates to a stacked coil component. Background Art

[0002] As one method for reducing the DC resistance of a stacked coil component, a method of forming an external electrode terminal thicker is known.

[0003] For example, Patent Document 1 discloses a stacked coil component including: a green body in which a coil is disposed inside; and an external electrode disposed on the surface of the green body and having a base metal layer and a conductive resin layer formed to cover the base metal layer. In this stacked coil component, by making the position where the connection conductor is exposed different from the position of the maximum thickness of the conductive resin layer, the DC resistance of the stacked coil component can be reduced.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2017-216290

[0005] In order to respond to the large current requirement of the stacked coil component, heat generation needs to be suppressed. In order to suppress heat generation of the stacked coil component, for example, reducing the current density is effective, and the stacked coil component described in Patent Document 1 can reduce the DC resistance (reduce the current density).

[0006] However, in the method described in Patent Document 1, the shape of a part that becomes a part of the external electrode expands significantly, so there is a concern about an increase in volume and a decrease in mounting density. Summary of the Invention

[0007] The present invention has been made to solve the above problems, and an object thereof is to provide a stacked coil component capable of reducing the current density without significantly changing the external shape of the chip.

[0008] The stacked coil component of the present invention includes: a stacked body formed by laminating a plurality of insulating layers and having a coil inside; and a first external electrode and a second external electrode electrically connected to the coil and formed by electrically connecting a plurality of coil conductors laminated together with the insulating layer. The stacked body has: a first end face and a second end face facing each other in the length direction, a first main face and a second main face facing each other in the height direction orthogonal to the length direction, and a first side face and a second side face facing each other in the width direction orthogonal to the length direction and the height direction. The first external electrode covers at least a part of the first end face, the second external electrode covers at least a part of the second end face, the coil axis of the coil is parallel to the first main face, a first recess is provided in the first end face, and the first recess has a deepest part inside the surrounding shape of the coil when the stacked body is viewed in perspective along the length direction, and the first external electrode covers at least a part of the first recess.

[0009] According to the present invention, a laminated coil component capable of reducing the current density without significantly changing the external shape of the chip can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 FIG. 1 is a perspective view schematically showing an example of the laminated coil component of the present invention.

[0011] Figure 2 FIG. 2 is a perspective exploded view schematically showing an example of a laminate constituting the laminated coil component shown in FIG. 1. Figure 1 FIG. 3 is a side view schematically showing an example of the internal structure of the laminate constituting the laminated coil component shown in FIG. 1 in a perspective manner.

[0012] Figure 3 FIG. 4 is a cross-sectional view schematically showing an example of a cross-section along line A1 - A1 of the laminated coil component shown in FIG. 1. Figure 1 FIG. 5 is a perspective view of the laminate constituting the laminated coil component shown in FIG. 1 as viewed from the first end face side.

[0013] Figure 4 FIG. 6 is a schematic view of a part of the internal structure of the laminate shown in FIG. 5 as viewed from the first end face side. Figure 1 FIG. 7 is a diagram showing a simulation result of the current density of the external electrode in the case where depressions are provided on the first end face and the second end face, respectively.

[0014] Figure 5 FIG. 8 is a diagram showing a simulation result of the current density of the external electrode in the case where no depressions are provided on the first end face and the second end face. Figure 1 FIG. 9 is a perspective view of the laminate constituting the laminated coil component shown in FIG. 1 as viewed from the first end face side.

[0015] Figure 6 FIG. 10 is a schematic view of a part of the internal structure of the laminate shown in FIG. 9 as viewed from the first end face side. Figure 5 FIG. 11 is a diagram showing a simulation result of the current density of the external electrode in the case where depressions are provided on the first end face and the second end face, respectively.

[0016] Figure 7 FIG. 12 is a diagram showing a simulation result of the current density of the external electrode in the case where no depressions are provided on the first end face and the second end face.

[0017] Figure 8 FIG. 13 is a diagram showing a simulation result of the current density of the external electrode in the case where depressions are provided on the first end face and the second end face, respectively.

[0018] Description of reference numerals: 1... laminated coil component; 10... laminate; 11... first end face; 11a... first recess; 11a1... deepest part of the first recess; 11b... first annular protrusion; 11b1... vertex of the first annular protrusion; 12... second end face; 12a... second recess; 12a1... deepest part of the second recess; 12b... second annular protrusion; 12b1... vertex of the second annular protrusion; 13... first main surface; 14... second main surface; 15... first side surface; 16... second side surface; 21... first external electrode; 22... second external electrode; 30... coil; 31a, 31b, 31c, 31d, 31e, 31f... insulating layers; 32, 32a, 32b, 32c, 32d... coil conductors; 33, 33a, 33b, 33c, 33d, 33e, 33f... via conductors; 34, 34a, 34b, 34c, 34d... surrounding parts; 35, 35a, 35b, 35c, 35d, 35e, 35f... pads; 41... first lead conductor; 42... second lead conductor; A... coil axis of the coil; d1... depth of the deepest part of the first recess; d2... depth of the deepest part of the second recess; t 11 ... thickness of the first external electrode covering the vertex of the first annular protrusion; t 12 ... thickness of the first external electrode covering the deepest part of the first recess; t 21 ... thickness of the second external electrode covering the vertex of the second annular protrusion; t 22 ... thickness of the second external electrode covering the deepest part of the second recess. Detailed description of the preferred embodiments

[0019] Hereinafter, the laminated coil component of the present invention will be described. In addition, the present invention is not limited to the following structure, and may be appropriately modified without departing from the gist of the present invention. In addition, a structure in which a plurality of the following described preferred structures are combined is also the present invention.

[0020] The following drawings are schematic views, and sometimes their dimensions, scales of aspect ratios, etc. are different from those of actual products. In the drawings, the same or corresponding parts are denoted by the same reference numerals. In addition, in each figure, the same elements are denoted by the same reference numerals and repeated descriptions are omitted.

[0021] In this specification, terms indicating the relationship between elements (e.g., "parallel", "orthogonal", etc.) and terms indicating the shape of elements do not mean strict forms that only mean the literal meaning, but also mean substantially equivalent ranges, for example, ranges including differences of about several percent.

[0022] Each of the embodiments described below is an exemplification, and of course, partial replacement or combination of the structures shown in different embodiments can be performed. After the second embodiment, descriptions of matters common to the first embodiment are omitted, and only different points are described. In particular, the same operational effects brought about by the same structure are not sequentially mentioned in each embodiment.

[0023] Figure 1 It is a perspective view schematically showing an example of the stacked coil component of the present invention.

[0024] Figure 1 The stacked coil component 1 shown is provided with a stacked body (green body) 10, a first external electrode 21 provided on the outer surface of the stacked body 10, and a second external electrode 22. The stacked body 10 has a rectangular parallelepiped shape with six faces. The structure of the stacked body 10 will be described later, but it is formed by laminating a plurality of insulating layers and a plurality of coil conductors in the stacking direction, and a coil is provided inside. The first external electrode 21 and the second external electrode 22 are each electrically connected to the coil.

[0025] In the stacked coil component and the stacked body in this specification, the length direction, the height direction, and the width direction are set as Figure 1 the L direction, the T direction, and the W direction in

[0026] Here, the length direction L is a direction parallel to the stacking direction.

[0027] As Figure 1 shown, the stacked body 10 has a first end face 11 and a second end face 12 facing each other in the length direction L, a first main face 13 and a second main face 14 facing each other in the height direction T orthogonal to the length direction L, and a first side face 15 and a second side face 16 facing each other in the width direction W orthogonal to the length direction L and the height direction T.

[0028] Although not shown in Figure 1 it, it is preferable that the stacked body 10 has rounded corners and ridge lines. A corner is a part where three faces of the stacked body intersect, and a ridge line is a part where two faces of the stacked body intersect.

[0029] A first recess 11a is provided on the first end face 11 of the stacked body 10.

[0030] In addition, a second recess 12a is also provided on the second end face 12 of the stacked body 10.

[0031] For example, as Figure 1As shown, the first external electrode 21 covers the entire first end face 11 of the laminate 10, and extends from the first end face 11 to cover a part of the first main face 13, a part of the second main face 14, a part of the first side face 15, and a part of the second side face 16.

[0032] When the first external electrode 21 covers the entire first recess 11a, it may be impossible to confirm from the external shape of the first external electrode 21 that the first recess 11a is provided on the first end face 11 of the laminate 10. However, by exposing the cut surface obtained by cutting the laminated coil member along the coil axis direction, it is possible to confirm whether the first recess is formed on the first end face of the laminate.

[0033] For example, as Figure 1 shown, the second external electrode 22 covers the entire second end face 12 of the laminate 10, and extends from the second end face 12 to cover a part of the first main face 13, a part of the second main face 14, a part of the first side face 15, and a part of the second side face 16.

[0034] When the second external electrode 22 covers the entire second recess 12a, it may be impossible to confirm from the external shape of the second external electrode 22 that the second recess 12a is provided on the second end face 12 of the laminate 10. However, by exposing the cut surface obtained by cutting the laminated coil member along the coil axis direction, it is possible to confirm whether the second recess is formed on the second end face of the laminate.

[0035] When the laminated coil member 1 configured with the first external electrode 21 and the second external electrode 22 as described above is mounted on a substrate, any one of the first main face 13, the second main face 14, the first side face 15, and the second side face 16 of the laminate 10 becomes the mounting face.

[0036] However, it is sufficient that the first external electrode 21 extends from at least a part of the first end face 11 of the laminate 10 to the mounting face of the laminate 10.

[0037] Similarly, it is sufficient that the second external electrode 22 extends from at least a part of the second end face 12 of the laminate 10 to the mounting face of the laminate 10.

[0038] The first external electrode 21 and the second external electrode 22 can each be a single-layer structure or a multi-layer structure.

[0039] When the first external electrode 21 and the second external electrode 22 are each a single-layer structure, examples of the constituent material of each external electrode include Ag, Au, Cu, Pd, Ni, Al, an alloy containing at least one of these metals, and the like.

[0040] In the case where the first external electrode 21 and the second external electrode 22 are each a multilayer structure, each external electrode may also have, for example, a base electrode layer containing Ag, a Ni coating film, and a Sn coating film in this order from the surface side of the laminate 10.

[0041] The size of the laminated coil component of the present invention is not particularly limited, and is preferably 1608 size or more in JIS C 5101-21(2021) (however, the symbol M indicating that the size is in metric is omitted).

[0042] Figure 2 is a schematic representation of Figure 1 an exploded perspective view of an example of the laminate constituting the laminated coil component shown.

[0043] As Figure 2 shown, the laminate 10 is formed by laminating a plurality of insulating layers 31a, 31b, 31c, 31d, 31e, and 31f from the first end face 11 side of the laminate 10 toward the second end face 12 side in the lamination direction (here, the length direction L). Hereinafter, the insulating layers 31a, 31b, 31c, 31d, 31e, and 31f will also be collectively referred to as the insulating layer 31.

[0044] In addition, in the present specification, the direction in which a plurality of insulating layers constituting the laminate are stacked is referred to as the lamination direction.

[0045] In Figure 2 it, the insulating layer 31e is disposed on the lower side in the lamination direction (the first end face 11 side of the laminate 10), and the insulating layer 31f is disposed on the upper side in the lamination direction (the second end face 12 side of the laminate 10).

[0046] As a constituent material of each insulating layer 31, for example, a magnetic material such as a ferrite material is listed.

[0047] Coil conductors 32a, 32b, 32c, and 32d and via conductors 33a, 33b, 33c, and 33d are provided in the insulating layers 31a, 31b, 31c, and 31d, respectively. A via conductor 33e and a pad 35e are provided in the insulating layer 31e. A via conductor 33f and a pad 35f are provided in the insulating layer 31f. The insulating layer 31e may be one layer or two or more layers. Similarly, the insulating layer 31f may be one layer or two or more layers. Hereinafter, the coil conductors 32a, 32b, 32c, and 32d will also be collectively referred to as the coil conductor 32.

[0048] The coil conductors 32a, 32b, 32c, and 32d are respectively provided on the main surfaces of the insulating layers 31a, 31b, 31c, and 31d and are laminated together with the insulating layers 31a, 31b, 31c, 31d, 31e, and 31f. In Figure 2In this case, each coil conductor 32 has a 3 / 4 turn shape, and four insulating layers 31 arranged in the order of insulating layers 31a, 31b, 31c, and 31d are repeatedly laminated as one unit (the amount of 3 turns).

[0049] In addition, the coil conductors 32a, 32b, 32c, and 32d respectively include annular surrounding portions 34a, 34b, 34c, and 34d that are lacking one place and have a locally vacant gap, and pads 35a, 35b, 35c, and 35d. Pads 35a, 35b, 35c, and 35d are provided at both end portions of each of the surrounding portions 34a, 34b, 34c, and 34d. Hereinafter, the surrounding portions 34a, 34b, 34c, and 34d will also be collectively referred to as the surrounding portion 34.

[0050] The via conductors 33a, 33b, 33c, 33d, 33e, and 33f are respectively provided to penetrate the insulating layers 31a, 31b, 31c, 31d, 31e, and 31f in the lamination direction. Hereinafter, the via conductors 33a, 33b, 33c, 33d, 33e, and 33f will also be collectively referred to as the via conductor 33.

[0051] Pads 35e and 35f are respectively provided directly above the via conductors 33e and 33f. It is preferable that the pads 35a, 35b, 35c, 35d, 35e, and 35f are slightly wider than the line width of the surrounding portions 34a, 34b, 34c, and 34d. Hereinafter, the pads 35a, 35b, 35c, 35d, 35e, and 35f will also be collectively referred to as the pad 35.

[0052] As the constituent materials of each coil conductor 32 and each via conductor 33 including the surrounding portion 34 and the pad 35, for example, Ag, Au, Cu, Pd, Ni, Al, alloys containing at least one of these metals, etc. are listed.

[0053] The plurality of insulating layers 31a, 31b, 31c, 31d, 31e, and 31f configured as described above are laminated in the lamination direction. Thereby, the laminate 10 is formed, and the plurality of coil conductors 32a, 32b, 32c, and 32d are electrically connected via the via conductors 33a, 33b, 33c, and 33d. As a result, a solenoid-shaped coil having a coil axis parallel to the lamination direction is formed within the laminate 10.

[0054] In addition, the via conductor 33e and the pad 35e become the first connection lead-out conductor within the laminate 10 and are exposed at the first end face 11 of the laminate 10. That is, the first connection lead-out conductor includes the via conductor 33e and the pad 35e. As will be described later, the first connection lead-out conductor connects the first external electrode 21 and the coil conductor 32a opposed thereto within the laminate 10.

[0055] The via conductor 33f and the pad 35f become the second connection lead conductor within the laminate 10 and are exposed at the second end face 12 of the laminate 10. That is, the second connection lead conductor includes the via conductor 33f and the pad 35f. As will be described later, the second connection lead conductor connects the second external electrode 22 and the coil conductor 32d opposed thereto within the laminate 10.

[0056] When viewed in the stacking direction (length direction L), it is preferable that the coil conductors 32 overlap each other. In addition, when viewed in the stacking direction, the coil may be Figure 2 a shape composed of straight portions (e.g., a polygonal shape such as a rectangle) as shown, a shape composed of curved portions (e.g., a circle), or a shape composed of straight portions and curved portions.

[0057] Figure 3 is a side view schematically showing an example of the internal structure of the laminate of the stacked coil component shown in a perspective view Figure 1 of the laminate.

[0058] As Figure 3 shown, in the stacked coil component 1, a plurality of insulating layers 31 are stacked in the length direction L, so the length direction L is the stacking direction. In addition, the stacking direction of the laminate 10 and the coil axis A of the coil 30 are parallel to any one of the first main surface 13, the second main surface 14, the first side surface 15, and the second side surface 16, which is the mounting surface, for example, the first main surface 13.

[0059] In addition, as Figure 3 shown, actually, no boundary can be confirmed between adjacent insulating layers 31.

[0060] The first connection lead conductor 41 extends in the stacking direction within the laminate 10 and linearly connects the first external electrode 21 provided on the first end face 11 and the coil conductor 32a opposed thereto. Similarly, the second connection lead conductor 42 extends in the stacking direction within the laminate 10 and linearly connects the second external electrode 22 provided on the second end face 12 and the coil conductor 32d opposed thereto.

[0061] In addition, when viewed in the stacking direction (length direction L), it is preferable that the via conductors constituting the connection lead conductor overlap each other, but the via conductors constituting the connection lead conductor may not be strictly linearly arranged with respect to each other.

[0062] In addition, in Figure 2 and Figure 3 an example is shown in which the number of stacked coil conductors 32 for forming 3 turns of the coil 30 is 4, that is, the repeating shape is a 3 / 4 turn shape, but the number of stacked coil conductors 32 for forming 1 turn of the coil 30 is not particularly limited.

[0063] For example, the number of layers of the coil conductor 32 that forms one turn of the coil 30 may be 2, that is, the repeating shape is a 1 / 2 turn shape.

[0064] In addition, the number of layers of the coil conductor 32, that is, the total number of layers of all the coil conductors 32 included in the laminate 10 is not particularly limited, and is preferably 30 or more and 120 or less.

[0065] Figure 4 is schematically showing Figure 1 a cross-sectional view of an example of the cross-section along the line A1 - A1 of the laminated coil component shown.

[0066] As Figure 4 shown, when observing the cross-section in a direction perpendicular to the extending direction of the coil conductor 32, the cross-sectional shape of the coil conductor 32 is a flat shape (long strip shape), and the long side direction thereof is orthogonal to the lamination direction (length direction L). In Figure 4 the example shown, the cross-sectional shape of the coil conductor 32 is an ellipse with the major axis orthogonal to the lamination direction, but the cross-sectional shape of the coil conductor 32 is not particularly limited. For example, it may also be a rectangle in which the lengths of a pair of opposite sides facing each other in the lamination direction are the same, a trapezoid in which the lengths of a pair of opposite sides facing each other in the lamination direction are different, or the like.

[0067] In Figure 4 the first end face 11 of the laminate 10 shown, a first recess 11a is provided.

[0068] The first recess 11a is a macroscopic recess formed by the part of the first end face 11 of the laminate 10 that overlaps with the surrounding shape of the coil when the laminate 10 is viewed through in the length direction L bulging relatively, and the part inside thereof being recessed relatively. Therefore, the first recess is different from the minute unevenness formed on the surface of the laminate. The same applies to the second recess described later.

[0069] The first recess 11a provided on the first end face 11 has a deepest part 11a1 inside the surrounding shape of the coil when the laminate 10 is viewed through in the length direction L.

[0070] A first annular protrusion 11b is provided on the first end face 11 of the laminate 10, and the first annular protrusion 11b protrudes annularly in a direction opposite to the depth direction of the first recess 11a, that is, outward of the laminate 10 and overlaps with the surrounding shape of the coil.

[0071] In addition, the depth d1 of the deepest part 11a1 of the first recess 11a is the length in the length direction L from the deepest part 11a1 of the first recess 11a to the most protruding part of the first end face 11, that is, the vertex 11b1 of the first annular protrusion 11b.

[0072] Here, the laminate is ground from the side surface (LT surface) of the laminate to the center in the width direction W to expose the LT cross-section. In the cross-sectional image obtained by using a digital microscope or the like for this cross-section, the dimensional difference between the lowest part (the most recessed part) and the highest part (the most protruding part, i.e., the vertex corresponding to the first annular convex part) of the insulating layer in the length direction L is measured by using a parallel dimension measurement tool or the like, and is used as the depth of the deepest part of the first recess of the first end face.

[0073] In addition, since the first annular convex part 11b extends annularly corresponding to the surrounding shape of the coil, the vertex 11b1 of the first annular convex part 11b does not represent the most protruding part of the first annular convex part, but represents the ridge line that exists annularly at the position overlapping with the surrounding shape of the coil. The entire region surrounded by the vertex 11b1 of the first annular convex part 11b corresponds to the first recess 11a.

[0074] The first annular convex part is arranged to overlap with the surrounding shape of the coil. In contrast, the deepest part of the first recess is arranged inside the surrounding shape of the coil. Therefore, when the laminate is viewed in perspective along the length direction L, it can be said that the first recess is arranged inside the first annular convex part.

[0075] The first external electrode 21 is formed to cover the deepest part 11a1 of the first recess 11a and the vertex 11b1 of the first annular convex part 11b.

[0076] Figure 4 The shown first external electrode 21 covers the entire first end face 11 of the laminate 10, and extends from the first end face 11 to cover a part of the first main face 13, the second main face 14, the first side face 15, and the second side face 16. However, in the laminated coil component of the present invention, it is sufficient that the first external electrode covers at least a part of the first recess of the first end face and a part of the surface that becomes the mounting surface.

[0077] For example, the first external electrode may also be an L-shaped electrode that covers a part of the first end face and extends from the first end face to cover the surface that becomes the mounting surface (for example, the second main face). In addition, the first external electrode may also be an inclined electrode that covers a part of the first end face, extends from the first end face to cover a part of the surface that becomes the mounting surface (for example, the second main face), and extends from the first end face and the mounting surface (for example, the second main face) to cover a part of the first side face and the second side face.

[0078] The first external electrode and the second external electrode may also be resin electrode layers formed by applying a conductive paste such as a paste containing Ag and glass powder to the first end face and the second end face of the laminate and firing them. If the first external electrode and the second external electrode are resin electrode layers, even when the substrate is flexed after installation, it is easy to relieve the stress transmitted from the substrate, and the connection reliability is excellent.

[0079] The first external electrode 21 covers at least a part of the first recess 11a, so that the first external electrode 21 can be prevented from protruding outward, and the thickness of the first external electrode 21 is increased by an amount commensurate with the depth of the first recess 11a. Therefore, the current density can be reduced without significantly changing the external shape of the chip.

[0080] Refer to Figure 5 and Figure 6 , the first recess provided on the first end face of the laminate will be described.

[0081] Figure 5 is a perspective view of the laminate constituting the Figure 1 laminated coil component as viewed from the first end face side. Figure 6 is a schematic view of a state of a part of the internal structure of the laminate as viewed from the first end face side in perspective Figure 5 as shown.

[0082] As Figure 5 and Figure 6 shown, a first recess 11a is provided on the first end face 11 of the laminate 10. As Figure 6 shown, the first recess 11a has a deepest part 11a1 inside the surrounding shape of the coil. In addition, it is also possible that a part other than the deepest part of the first recess 11a overlaps with the surrounding shape of the coil.

[0083] As Figure 5 and Figure 6 shown, a first annular protrusion 11b is provided on the first end face 11 of the laminate. As Figure 6 shown, the first annular protrusion 11b is annular and is provided to overlap with the surrounding shape of the coil.

[0084] When scanning the first annular protrusion 11b from the inside to the outside of the surrounding shape of the coil, the point farthest from the deepest part 11a1 of the first recess 11a in the longitudinal direction L is set as the vertex 11b1 of the first annular protrusion 11b. The vertex 11b1 of the first annular protrusion 11b is provided in an annular shape at a position overlapping with the surrounding shape of the coil.

[0085] The first recess 11a is a macroscopic recess formed in the first end face 11 of the laminate 10, where the portion overlapping the surrounding shape of the coil when the laminate 10 is viewed in perspective along the length direction L bulges relatively, and the inner portion is recessed relatively. Therefore, the first recess is different from the minute unevenness formed on the surface of the laminate. The same applies to the second recess described later.

[0086] Preferably, the maximum thickness of the first external electrode is greater than the depth of the deepest part of the first recess.

[0087] In Figure 4 the laminated coil component 1 shown, the maximum thickness of the first external electrode 21 (in Figure 4 it, the length indicated by the double arrow t 12 is greater than the depth d1 of the deepest part 11a1 of the first recess 11a.

[0088] In addition, the thickness of the first external electrode covering the deepest part of the first recess may also be the maximum thickness of the first external electrode. In Figure 4 the laminated coil component 1 shown, the thickness t 12 of the first external electrode 21 covering the deepest part 11a1 of the first recess 11a becomes the maximum thickness of the first external electrode 21.

[0089] Preferably, the first external electrode covers the deepest part of the first recess.

[0090] In Figure 4 the laminated coil component 1 shown, the first external electrode 21 covers the deepest part 11a1 of the first recess 11a on the first end face 11 of the laminate 10.

[0091] If the first external electrode covers the deepest part of the first recess, the thickness of the first external electrode can be maximized without significantly changing the external shape of the chip.

[0092] On the first end face, there is a portion protruding in a ring shape, that is, the first ring-shaped convex portion. When the laminate is viewed in perspective along the length direction, preferably, the first ring-shaped convex portion overlaps the surrounding shape of the coil.

[0093] In this case, preferably, the first external electrode covers at least a part of the vertex of the first ring-shaped convex portion on the first end face.

[0094] In addition, at this time, preferably, the thickness of the first external electrode covering the deepest part of the first recess is thicker than the thickness of the first external electrode covering at least a part of the vertex of the first ring-shaped convex portion.

[0095] If the thickness of the first external electrode covering the deepest part of the first recess is thicker than the thickness of the first external electrode covering the vertex of the first ring-shaped convex portion, the first external electrode is formed so as to bury the first recess, and thus the effect of suppressing the current density is high.

[0096] In Figure 4 in the stacked coil component 1 shown, at the first end face 11 of the stacked body 10, at a position overlapping the surrounding shape (coil conductor 32) of the coil in the length direction L, a portion where the first end face 11 protrudes annularly, that is, the first annular convex portion 11b, is provided. The first external electrode 21 covers all of the vertex 11b1 of the first annular convex portion 11b.

[0097] The thickness t of the first external electrode 21 covering the deepest part 11a1 of the first recess 11a 12 is larger than the thickness t of the first external electrode 21 covering the vertex 11b1 of the first annular convex portion 11b. 11 is larger.

[0098] Preferably, the portion where the thickness of the first external electrode is the thickest is provided at a position overlapping the first recess, which is the part on the inner side of the surrounding shape of the coil when the stacked body is viewed in perspective in the length direction.

[0099] In Figure 4 in the stacked coil component 1 shown, the position where the thickness of the first external electrode 21 is the largest is the position overlapping the deepest part 11a1 of the first recess 11a.

[0100] In addition, in Figure 4 in the stacked coil component 1 shown, no recess is formed on the surface of the first external electrode 21 covering the surface of the first end face 11 of the stacked body 10, but within a range where the external appearance shape of the chip is not significantly changed, the shape of the first external electrode 21 covering the surface of the first end face 11 of the stacked body may be slightly recessed inward according to the first recess 11a, or may be slightly bulged outward conversely.

[0101] For example, the first external electrode 21 covering the surface of the first end face 11 of the stacked body may also have a recess shallower than the first recess, similar to the first recess of the first end face 11. This occurs, for example, when the shape of the first external electrode covering the first end face of the stacked body follows the shape of the first end face 11 to some extent.

[0102] Preferably, the depth of the deepest part of the first recess is 30 μm or more and 50 μm or less.

[0103] In Figure 4 in the stacked coil component 1 shown, preferably, the depth d1 of the deepest part 11a1 of the first recess 11a is 30 μm or more and 50 μm or less.

[0104] If the depth of the deepest part of the first recess is within the above range, even when the external electrode is formed by the dip coating method, the mixing of bubbles is suppressed, and thus the formation defect of the external electrode can be suppressed.

[0105] Preferably, the thickness of the first external electrode covering the deepest part of the first recess is 30 μm or more and 100 μm or less.

[0106] In addition, preferably, the maximum thickness of the external electrode of the first external electrode that does not cover the first recess is 20% or more and 100% or less of the thickness of the external electrode covering the deepest part of the first recess.

[0107] For the second end face of the laminate and the second external electrode, the same structure as the first end face and the first external electrode of the above laminate may be provided.

[0108] A second recess having the deepest part inside the surrounding shape of the coil may be provided on the second end face of the laminate when the laminate is viewed through in the length direction.

[0109] In Figure 4 A second recess 12a is provided on the second end face 12 of the laminate 10 shown.

[0110] The second recess 12a provided on the second end face 12 has the deepest part 12a1 inside the surrounding shape of the coil when the laminate 10 is viewed through in the length direction L.

[0111] In Figure 4 A second annular convex portion 12b is provided on the second end face 12 of the laminate 10 shown. The second annular convex portion 12b projects annularly toward the outside of the laminate 10, that is, in the direction opposite to the depth direction of the second recess 12a, and overlaps with the surrounding shape of the coil. When scanning the second annular convex portion 12b from the inside to the outside of the surrounding shape of the coil, the point farthest from the second recess 12a in the length direction is set as the vertex 12b1 of the second annular convex portion 12b. That is, the vertex 12b1 of the second annular convex portion 12b is provided in a ring shape at a position overlapping with the surrounding shape of the coil. Therefore, the length from the deepest part 12a1 of the second recess 12a to the vertex 12b1 of the second annular convex portion 12b in the length direction L becomes the depth d2 of the deepest part 12a1 of the second recess 12a.

[0112] The second external electrode 22 is formed to cover the deepest part 12a1 of the second recess 12a and the vertex 12b1 of the second annular convex portion 12b.

[0113] On the second end face, a portion projecting annularly, that is, the second annular convex portion, is provided. When the laminate is viewed through in the length direction L, preferably, the second annular convex portion overlaps with the surrounding shape of the coil.

[0114] In this case, preferably, the second external electrode covers at least a part of the vertex of the second annular convex portion in the second end face.

[0115] Further, at this time, preferably, the thickness of the second external electrode covering the deepest part of the second recess is thicker than the thickness of the second external electrode covering at least a part of the vertex of the second annular protrusion.

[0116] Preferably, the depth d2 of the deepest part 12a1 of the second recess 12a is 30 μm or more and 50 μm or less.

[0117] Figure 7 It is a diagram showing the simulation results of the current density of the external electrode in the case where recesses are provided on the first end face and the second end face, respectively. Figure 8 It is a diagram showing the simulation results of the current density of the external electrode in the case where no recesses are provided on the first end face and the second end face.

[0118] In addition, in Figure 7 the simulation shown, in a stacked coil component having a size of 2012 (L×W×T = 2.0 mm×1.25 mm×1.25 mm), recesses (first recess and second recess) having a depth of 30 μm at the deepest part are provided on the first end face and the second end face of the stacked body, and an external electrode having a thickness of 40 μm is formed.

[0119] The maximum thickness of the first external electrode covering the deepest part of the first recess is set to 70 μm, and the thickness of the first external electrode covering the portion of the first end face other than the first recess is set to 40 μm. Further, the maximum thickness of the second external electrode covering the deepest part of the second recess is set to 70 μm, and the thickness of the second external electrode covering the portion of the second end face other than the second recess is set to 40 μm.

[0120] In Figure 8 the simulation shown, the shape of the stacked body is changed from Figure 7 the state where there are no first recess and second recess formed. That is, no first recess and second recess are provided on the first end face and the second end face of the stacked body, and the first end face and the second end face are flat. The thickness of the first external electrode covering the first end face and the second external electrode covering the second end face is 40 μm at all parts.

[0121] It was confirmed that the maximum value of the current density in Figure 8 is 55.1 MA / m 2 , and in contrast, in Figure 7 the maximum value of the current density can be reduced to 47.4 MA / m 2 .

[0122] Therefore, it can be known that the stacked coil component of the present invention can reduce the current density without significantly changing the external shape.

[0123] Hereinafter, an example of the manufacturing method of the stacked coil component of the present invention will be described.

[0124] <Manufacturing Process of Magnetic Material>

[0125] First, weigh Fe2O3, ZnO, CuO, and NiO to achieve a specified ratio.

[0126] Next, after putting these weighed substances, pure water, etc. together with PSZ (partially stabilized zirconia) media into a ball mill for mixing, perform pulverization. Regarding the mixing and pulverization time, for example, set it to be 4 hours or more and 8 hours or less.

[0127] Then, after drying the obtained pulverized material, perform calcination. Regarding the calcination temperature, for example, set it to be 700 °C or more and 800 °C or less. Regarding the calcination time, for example, set it to be 2 hours or more and 5 hours or less.

[0128] In this way, a powdery magnetic material, more specifically a powdery magnetic ferrite material, is manufactured.

[0129] The ferrite material is preferably a Ni-Cu-Zn series ferrite material.

[0130] Regarding the Ni-Cu-Zn series ferrite material, when the total amount is set to 100 mol%, it preferably contains 40 mol% or more and 49.5 mol% or less in terms of Fe converted to Fe2O3, 2 mol% or more and 35 mol% or less in terms of Zn converted to ZnO, 6 mol% or more and 13 mol% or less in terms of Cu converted to CuO, and 10 mol% or more and 45 mol% or less in terms of Ni converted to NiO.

[0131] The Ni-Cu-Zn series ferrite material may further contain additives such as Co, Bi, Sn, and Mn.

[0132] The Ni-Cu-Zn series ferrite material may further contain inevitable impurities.

[0133] <Manufacturing Process of Green Ceramic Sheets>

[0134] First, after putting the magnetic material, an organic binder such as polyvinyl butyral resin, organic solvents such as ethanol and toluene, and a plasticizer, etc. together with PSZ media into a ball mill for mixing, perform pulverization to produce a slurry.

[0135] Next, after forming the slurry into a sheet with a specified thickness by a doctor blade method or the like, cut it into a specified shape to produce green ceramic sheets. Regarding the thickness of the green ceramic sheets, for example, set it to be 20 μm or more and 30 μm or less. Regarding the shape of the green ceramic sheets, for example, set it to be rectangular.

[0136] As a material for a green sheet of ceramics, instead of a magnetic material, a non-magnetic material such as a borosilicate glass material may be used, or a mixed material of a magnetic material and a non-magnetic material may be used.

[0137] <Forming process of conductor pattern>

[0138] First, a through-hole is formed by irradiating a predetermined portion of the green sheet of ceramics with a laser.

[0139] Next, a conductive paste such as an Ag paste is filled into the through-hole and coated on the surface of the green sheet of ceramics by a screen printing method or the like. Thus, for the green sheet of ceramics, a conductor pattern for a via-hole conductor is formed in the through-hole, and a conductor pattern for a coil conductor connected to the conductor pattern for the via-hole conductor is formed on the surface. In this way, a coil sheet having a conductor pattern for a coil conductor and a conductor pattern for a via-hole conductor formed thereon is produced. On the coil sheet, there is formed a conductor pattern for a coil conductor corresponding to Figure 2 the coil conductor 32 shown, and a conductor pattern for a via-hole conductor corresponding to Figure 2 the via-hole conductor 33 (except for the via-hole conductors 33e and 33f) shown. In addition, a via-hole sheet having a conductor pattern for a via-hole conductor corresponding to Figure 2 the via-hole conductors 33e and 33f shown is separately produced.

[0140] <Manufacturing process of laminated body block>

[0141] After laminating the coil sheet and the via-hole sheet in the lamination direction (length direction L) in a sequence corresponding to Figure 2 a certain one, thermocompression bonding is performed to produce a laminated body block.

[0142] At this time, thermocompression bonding is performed in such a way that a first recess and a second recess are respectively formed on the surfaces of the laminated body that become the first end face and the second end face.

[0143] The method of forming the first recess on the surface of the laminated body that becomes the first end face is not particularly limited. For example, the following method can be cited: after laminating the coil sheet and the via-hole sheet to produce a laminated sheet, at the time of thermocompression bonding, a convex portion corresponding to the first recess is previously formed on the surface of the punching die in contact with the upper surface of the laminated sheet.

[0144] Similarly, the method of forming the second recess on the surface of the laminated body that becomes the second end face is not particularly limited. For example, the following method can be cited: after laminating the coil sheet and the via-hole sheet to produce a laminated sheet, at the time of thermocompression bonding, a convex portion corresponding to the second recess is previously formed on the surface of the base (punching die) in contact with the bottom surface of the laminated sheet.

[0145] Therefore, when the stacked sheets are hot-pressed, convex portions are pre-formed on the surface of the stamping metal mold in contact with the upper surface of the stacked sheets and the surface of the base (stamping metal mold) in contact with the bottom surface of the stacked sheets, respectively, so that a stacked body can be manufactured having a first recess and a second recess formed on the first end face and the second end face, respectively.

[0146] like Figure 2 As shown, the first end face and the second end face of the stack face each other in the stacking direction of the insulating layer. Therefore, the shape of the surface of the stamping metal mold that contacts the upper surface or bottom surface of the stack when the stack is hot-pressed is reflected in the shape of the first end face of the stack.

[0147] The position and depth of the first recess and the position and depth of the second recess can be appropriately adjusted by the shape of the protrusion provided on the surface of the metal mold.

[0148] In addition, the shape of the stamping metal mold itself can be set to have the shape of the above-mentioned convex portion, or a stamping metal mold with a flat pressurizing surface can be used, and when the stacked sheet is pressurized, a component with a shape corresponding to the above-mentioned convex portion is clamped between the stamping metal mold and the stacked sheet.

[0149] In addition, in addition to the above-mentioned method and the method using a stamping metal mold, sometimes the first recess can be formed on the first end face of the stack by adjusting the thickness of the via sheet or coil sheet, the number of layers, etc., or changing the conditions of hot pressing.

[0150] <Laminate and coil production process>

[0151] First, the laminated body block is cut into predetermined sizes using a dicing machine or the like, thereby producing individual chips.

[0152] Next, the individual chips are fired. The firing temperature is, for example, 900° C. or higher and 920° C. or lower. The firing time is, for example, 2 hours or higher and 4 hours or lower.

[0153] When the individual chips are fired, the ceramic green sheets of the coil sheet and the via sheet serve as insulating layers.

[0154] When the individual chips are fired, the coil conductor pattern and the via conductor pattern become coil conductors and via conductors, respectively. As a result, a coil is produced in which a plurality of coil conductors stacked together with an insulating layer are electrically connected via via conductors.

[0155] Based on the above, a laminated body is produced in which a plurality of insulating layers are laminated in the lamination direction and the coil is built therein.

[0156] For a laminate, for example, corner portions and ridge line portions can also be rounded by performing barrel polishing.

[0157] <External electrode forming process>

[0158] First, a conductive paste such as a paste containing Ag and glass powder is applied to the first end face and the second end face of the lead-out coil on the outer surface of the laminate, thereby forming a conductive paste layer.

[0159] As a method for applying the conductive paste, a conventionally well-known method can be used, such as a dipping method, a method of applying the conductive paste with a pen, or the like.

[0160] Next, the base electrode of the external electrode is formed by sintering the conductive paste layer. Regarding the sintering temperature, for example, it is set to 800 °C or higher and 820 °C or lower. Regarding the thickness of the base electrode, for example, it is set to 5 μm.

[0161] Then, a Ni plating electrode and a Sn plating electrode are sequentially formed on the surface of the base electrode by electroplating or the like. Thereby, an external electrode having a base electrode, a Ni plating electrode, and a Sn plating electrode in sequence is formed.

[0162] A first recess and a second recess are respectively provided on the first end face and the second end face of the laminate manufactured by the above steps. Therefore, a first external electrode and a second external electrode are respectively formed to cover the first recess and the second recess, thereby manufacturing the laminated coil component of the present invention.

[0163] The following matters are described in this specification.

[0164] The present disclosure (1) is a laminated coil component, wherein,

[0165] comprises: a laminate formed by laminating a plurality of insulating layers and having a coil inside; and a first external electrode and a second external electrode electrically connected to the above coil,

[0166] the above coil is formed by electrically connecting a plurality of coil conductors laminated together with the above insulating layer,

[0167] the above laminate has: a first end face and a second end face facing each other in the length direction, a first main face and a second main face facing each other in the height direction orthogonal to the above length direction, and a first side face and a second side face facing each other in the width direction orthogonal to the above length direction and the above height direction,

[0168] the above first external electrode covers at least a part of the above first end face,

[0169] the above second external electrode covers at least a part of the above second end face,

[0170] The coil axis of the above coil is parallel to the above first main surface,

[0171] A first recess is provided in the above first end face, and the first recess has a deepest part inside the surrounding shape of the above coil when the above laminate is viewed in the above length direction.

[0172] The above first external electrode covers at least a part of the above first recess.

[0173] The present disclosure (2) is in the laminated coil component described in the present disclosure (1),

[0174] The depth of the deepest part of the above first recess is 30 μm or more and 50 μm or less.

[0175] The present disclosure (3) is in the laminated coil component described in the present disclosure (1) or (2),

[0176] The maximum thickness of the above first external electrode is greater than the depth of the deepest part of the above first recess.

[0177] The present disclosure (4) is in the laminated coil component of any arbitrary combination of the present disclosures (1) to (3),

[0178] The above first external electrode covers the deepest part of the above first recess.

[0179] The present disclosure (5) is in the laminated coil component described in the present disclosure (4),

[0180] A first annular convex portion is provided on the above first end face, and the first annular convex portion is a portion that protrudes annularly.

[0181] When the above laminate is viewed in the above length direction, the above first annular convex portion overlaps with the surrounding shape of the above coil.

[0182] The above first external electrode covers at least a part of the vertex of the above first annular convex portion in the above first end face.

[0183] The thickness of the above first external electrode covering the deepest part of the above first recess is thicker than the thickness of the above first external electrode covering at least a part of the vertex of the above first annular convex portion.

[0184] The present disclosure (6) is in the laminated coil component of any arbitrary combination of the present disclosures (1) to (5),

[0185] A second recess is provided in the above second end face, and the second recess has a deepest part inside the surrounding shape of the above coil when the above laminate is viewed in the above length direction.

[0186] The second external electrode covers at least a part of the second recess.

Claims

1. A laminated coil component, wherein: The invention comprises: a laminated body formed by laminating a plurality of insulating layers and having a coil inside; and a first external electrode and a second external electrode electrically connected to the coil. The coil is formed by electrically connecting a plurality of coil conductors stacked together with the insulating layer, The stacked body has a first end face and a second end face facing each other in a length direction, a first main face and a second main face facing each other in a height direction perpendicular to the length direction, and a first side face and a second side face facing each other in a width direction perpendicular to the length direction and the height direction. The first external electrode covers at least a portion of the first end surface, The second external electrode covers at least a portion of the second end surface, The coil axis of the coil is parallel to the first main surface, A first depression is provided on the first end surface, the first depression having a deepest portion inside the encircling shape of the coil when the laminate is seen through in the longitudinal direction. The first external electrode covers at least a portion of the first recess.

2. The laminated coil component according to claim 1, wherein: The deepest portion of the first recess has a depth of 30 μm or more and 50 μm or less.

3. The laminated coil component according to claim 1 or 2, wherein: The maximum thickness of the first external electrode is greater than the depth of the deepest portion of the first recess.

4. The laminated coil component according to any one of claims 1 to 3, wherein: The first external electrode covers the deepest portion of the first recess.

5. The laminated coil component according to claim 4, wherein: A first annular convex portion is provided on the first end surface, wherein the first annular convex portion is a portion protruding in an annular shape. When the stacked body is viewed from above along the longitudinal direction, the first annular protrusion overlaps with the encircling shape of the coil. The first external electrode covers at least a portion of the apex of the first annular convex portion in the first end surface. The thickness of the first external electrode covering the deepest portion of the first recess is thicker than the thickness of the first external electrode covering the at least a portion of the apex of the first annular protrusion.

6. The laminated coil component according to any one of claims 1 to 5, wherein: A second recess is provided on the second end surface, the second recess having a deepest portion inside the loop shape of the coil when the laminate is viewed through along the longitudinal direction. The second external electrode covers at least a portion of the second recess.

Images