Lamination coil component

Abstract

To provide a lamination coil component capable of reducing a current density without extremely changing an exterior appearance shape of a chip.SOLUTION: A lamination coil component 1 comprises: a lamination body 10 that is formed by laminating a plurality of insulation layers 31, and which includes a coil inside; and a first external electrode 21 and a second external electrode 22 that are electrically connected to a coil 30. A plurality of coil conductors 32 laminated with the insulation layer are connected to the coil. The lamination body has: a first end surface 11 and a second end surface 12 in a length direction; a first main surface 13 and a second main surface 14 in a height direction; and a first side surface 15 and a second side surface 16 in a width direction. The first external electrode covers at least one part of the first end surface, and the second external electrode convers at least one part of the second end surface. A coil shaft of the coil is parallel to the first main surface, and a first concave 11a having a most depth part 11a1 in an inner side of a circulation shape of the coil is provided to the first end surface when the lamination body is seen through from the length direction. The first external electrode covers at least one part of the first concave.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a multilayer coil component.

Background Art

[0002] As one method of reducing the DC resistance of a multilayer coil component, a method of forming thick external electrode terminals is known.

[0003] For example, Patent Document 1 discloses that in a multilayer coil component having an element body in which a coil is disposed, an external electrode having an underlayer metal layer disposed on the surface of the element body and a conductive resin layer formed so as to cover the underlayer metal layer, 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 multilayer coil component can be reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to meet the high current requirements of a multilayer coil component, it is required to suppress heat generation. In order to suppress heat generation of a multilayer coil component, for example, it is effective to reduce the current density, and the multilayer coil component described in Patent Document 1 can reduce the DC resistance (reduce the current density). However, in the method described in Patent Document 1, since a part of the external electrode has a shape that significantly expands, there is a concern that the volume becomes large and the mounting density decreases.

[0006] The present invention has been made to solve the above problems, and an object thereof is to provide a multilayer coil component capable of reducing the current density without significantly changing the external shape of the chip.

Means for Solving the Problems

[0007] The multilayer coil component of the present invention includes a laminate in which a plurality of insulating layers are laminated and has a coil inside, 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 laminated together with the insulating layers. The laminate has a first end face and a second end face opposite to each other in the length direction, a first main face and a second main face opposite to each other in the height direction orthogonal to the length direction, and a first side face and a second side face opposite to 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, and a first depression having a deepest part inside the circumferential shape of the coil is provided on the first end face when the laminate is viewed through in the length direction. The first external electrode covers at least a part of the first depression.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a multilayer coil component capable of reducing the current density without significantly changing the external shape of the chip.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the multilayer coil component of the present invention will be described. Note that the present invention is not limited to the following configurations and may be appropriately changed without departing from the gist of the present invention. Also, combinations of a plurality of the individual preferred configurations described below are also within the scope of the present invention.

[0011] The drawings shown below are schematic diagrams, and their dimensions, scales of aspect ratios, etc. may differ from those of actual products. In the drawings, the same or corresponding parts will be denoted by the same reference numerals. Also, in each figure, the same elements will be denoted by the same reference numerals and redundant descriptions will be omitted.

[0012] In this specification, terms indicating the relationship between elements (e.g., "parallel", "orthogonal", etc.) and terms indicating the shape of elements do not mean only the exact strict aspect, but also mean a substantially equivalent range, for example, a range including a difference of about several percent.

[0013] Each of the embodiments described below is an example, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. In the second and subsequent embodiments, descriptions of matters common to the first embodiment are omitted, and only different points are explained. In particular, for similar operational effects due to similar configurations, they are not sequentially mentioned for each embodiment.

[0014] FIG. 1 is a perspective view schematically showing an example of a multilayer coil component of the present invention. The multilayer coil component 1 shown in FIG. 1 includes a laminate (element body) 10, a first external electrode 21, and a second external electrode 22 provided on the outer surface of the laminate 10. The laminate 10 has a rectangular parallelepiped shape having six faces. Although the configuration of the laminate 10 will be described later, a plurality of insulating layers and a plurality of coil conductors are laminated in the lamination 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.

[0015] In the multilayer coil component and the laminate in this specification, the length direction, the height direction, and the width direction are the L direction, the T direction, and the W direction in FIG. 1. Here, the length direction L, the height direction T, and the width direction W are orthogonal to each other. Here, the length direction L is a direction parallel to the lamination direction.

[0016] As shown in FIG. 1, the laminate 10 has a first end face 11 and a second end face 12 that face each other in the length direction L, a first main face 13 and a second main face 14 that face 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 that face each other in the width direction W orthogonal to the length direction L and the height direction T.

[0017] Although not shown in FIG. 1, it is preferable that the laminate 10 has rounded corners and ridgeline portions. A corner portion is a portion where three faces of the laminate intersect, and a ridgeline portion is a portion where two faces of the laminate intersect.

[0018] A first recess 11a is provided in the first end face 11 of the laminate 10. In addition, a second recess 12a is also provided on the second end face 12 of the laminate 10.

[0019] The first external electrode 21 covers, for example, as shown in FIG. 1, 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. When the first external electrode 21 covers the entire first recess 11a, it may not be possible 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 component along the coil axis direction, it is possible to confirm whether the first recess is formed on the first end face of the laminate.

[0020] The second external electrode 22 covers, for example, as shown in FIG. 1, 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. When the second external electrode 22 covers the entire second recess 12a, it may not be possible 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 component along the coil axis direction, it is possible to confirm whether the second recess is formed on the second end face of the laminate.

[0021] When mounting the laminated coil component 1 in which the first external electrode 21 and the second external electrode 22 are arranged as described above 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.

[0022] However, the first external electrode 21 only needs to extend from at least a part of the first end face 11 of the laminate 10 to the mounting face of the laminate 10.

[0023] Similarly, the second external electrode 22 may extend from at least a part of the second end face 12 of the laminate 10 over the mounting surface of the laminate 10.

[0024] The first external electrode 21 and the second external electrode 22 may each have a single-layer structure or a multilayer structure.

[0025] When the first external electrode 21 and the second external electrode 22 each have a single-layer structure, examples of the constituent material of each external electrode include Ag, Au, Cu, Pd, Ni, Al, alloys containing at least one of these metals, and the like.

[0026] When the first external electrode 21 and the second external electrode 22 each have a multilayer structure, each external electrode may have, in order from the surface side of the laminate 10, for example, a base electrode layer containing Ag, a Ni film, and a Sn film.

[0027] The size of the laminated coil component of the present invention is not particularly limited, but it is preferably 1608 size or more in JIS C 5101-21(2021) (however, the symbol M indicating that the dimensions are expressed in the metric system is omitted).

[0028] FIG. 2 is an exploded perspective view schematically showing an example of the laminate constituting the laminated coil component shown in FIG. 1.

[0029] As shown in FIG. 2, the laminate 10 is configured by laminating a plurality of insulating layers 31a, 31b, 31c, 31d, 31e, and 31f in the lamination direction (here, the length direction L) from the first end face 11 side to the second end face 12 side of the laminate 10. Hereinafter, the insulating layers 31a, 31b, 31c, 31d, 31e, and 31f will also be collectively referred to as the insulating layer 31.

[0030] In this specification, the direction in which a plurality of insulating layers constituting the laminate are stacked is referred to as the lamination direction.

[0031] In FIG. 2, the insulating layer 31e is disposed on the lower side in the stacking direction (the first end face 11 side of the stacked body 10), and the insulating layer 31f is disposed on the upper side in the stacking direction (the second end face 12 side of the stacked body 10).

[0032] Examples of the constituent material of each insulating layer 31 include magnetic materials such as ferrite materials.

[0033] The insulating layers 31a, 31b, 31c, and 31d are each provided with a coil conductor 32a, 32b, 32c, and 32d, and via conductors 33a, 33b, 33c, and 33d, respectively. The insulating layer 31e is provided with a via conductor 33e and a land 35e. The insulating layer 31f is provided with a via conductor 33f and a land 35f. The insulating layer 31e may be a single layer or two or more layers. Similarly, the insulating layer 31f may be a single 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.

[0034] 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 stacked together with the insulating layers 31a, 31b, 31c, 31d, 31e, and 31f. In FIG. 2, each coil conductor 32 has a 3 / 4 turn shape, and four insulating layers 31 arranged in the order of the insulating layers 31a, 31b, 31c, and 31d are used as one unit (for 3 turns) and repeatedly stacked.

[0035] In addition, the coil conductors 32a, 32b, 32c, and 32d each include an annular circumferential portion 34a, 34b, 34c, and 34d with one part missing and a partial gap, and lands 35a, 35b, 35c, and 35d. Lands 35a, 35b, 35c, and 35d are respectively provided at both ends of each circumferential portion 34a, 34b, 34c, and 34d. Hereinafter, the circumferential portions 34a, 34b, 34c, and 34d will also be collectively referred to as the circumferential portion 34.

[0036] The via conductors 33a, 33b, 33c, 33d, 33e, and 33f are each provided so as to penetrate the insulating layers 31a, 31b, 31c, 31d, 31e, and 31f in the stacking direction. Hereinafter, the via conductors 33a, 33b, 33c, 33d, 33e, and 33f are also collectively referred to as the via conductor 33.

[0037] Lands 35e and 35f are respectively provided directly above the via conductors 33e and 33f. The lands 35a, 35b, 35c, 35d, 35e, and 35f are preferably slightly larger than the line widths of the circumferential portions 34a, 34b, 34c, and 34d. Hereinafter, the lands 35a, 35b, 35c, 35d, 35e, and 35f are also collectively referred to as the land 35.

[0038] Examples of the constituent materials of each coil conductor 32 including the circumferential portion 34 and the land 35 and each via conductor 33 include Ag, Au, Cu, Pd, Ni, Al, alloys containing at least one of these metals, and the like.

[0039] The plurality of insulating layers 31a, 31b, 31c, 31d, 31e, and 31f configured as described above are stacked in the stacking direction. Thereby, the stacked body 10 is configured, 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 stacking direction is formed in the stacked body 10.

[0040] Also, the via conductor 33e and the land 35e serve as a first connection lead-out conductor within the stacked body 10 and are exposed on the first end face 11 of the stacked body 10. That is, the first connection lead-out conductor includes the via conductor 33e and the land 35e. As will be described later, the first connection lead-out conductor connects between the first external electrode 21 and the coil conductor 32a facing the same within the stacked body 10.

[0041] The via conductor 33f and the land 35f serve as the second connection lead-out conductor within the laminate 10 and are exposed on the second end face 12 of the laminate 10. That is, the second connection lead-out conductor includes the via conductor 33f and the land 35f. As will be described later, the second connection lead-out conductor connects between the second external electrode 22 and the coil conductor 32d facing it within the laminate 10.

[0042] When viewed from the stacking direction (length direction L), it is preferable that the coil conductors 32 overlap each other. Also, when viewed from the stacking direction, the coil may have a shape composed of straight portions as shown in FIG. 2 (for example, a polygonal shape such as a rectangle), a shape composed of curved portions (for example, a circular shape), or a shape composed of straight portions and curved portions.

[0043] FIG. 3 is a side view schematically showing a perspective view of an example of the internal structure of the laminate constituting the laminated coil component shown in FIG. 1.

[0044] As shown in FIG. 3, in the laminated coil component 1, since a plurality of insulating layers 31 are laminated in the length direction L, the length direction L is the stacking direction. Also, 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, or the second side surface 16, which is the mounting surface, for example, the first main surface 13.

[0045] Note that, as shown in FIG. 3, actually, no boundary is visually recognized between adjacent insulating layers 31.

[0046] The first connection lead-out conductor 41 extends in the stacking direction within the laminate 10 and linearly connects between the first external electrode 21 provided on the first end face 11 and the coil conductor 32a facing it. Similarly, the second connection lead-out conductor 42 extends in the stacking direction within the laminate 10 and linearly connects between the second external electrode 22 provided on the second end face 12 and the coil conductor 32d facing it.

[0047] When viewed from the stacking direction (length direction L), it is preferable that the via conductors constituting the connecting and lead-out conductor overlap each other, but the via conductors constituting the connecting and lead-out conductor do not necessarily have to be arranged strictly linearly.

[0048] In FIGS. 2 and 3, when the number of stacked coil conductors 32 for forming three turns of the coil 30 is four, that is, when the repeating shape is a 3 / 4 turn shape, this case is illustrated. However, the number of stacked coil conductors 32 for forming one turn of the coil 30 is not particularly limited. For example, the number of stacked coil conductors 32 for forming one turn of the coil 30 may be two, that is, the repeating shape may be a 1 / 2 turn shape.

[0049] Also, the number of stacked coil conductors 32, that is, the total number of stacked coil conductors 32 included in the stacked body 10 is not particularly limited, but it is preferably 30 or more and 120 or less.

[0050] FIG. 4 is a cross-sectional view schematically showing an example of a cross-section along the line segment A1 - A1 of the stacked coil component shown in FIG. 1.

[0051] As shown in FIG. 4, when looking at a cross-section in a direction perpendicular to the direction in which the coil conductor 32 extends, the cross-sectional shape of the coil conductor 32 is a flat shape (longitudinal shape), and its longitudinal direction is orthogonal to the stacking direction (length direction L). In the example shown in FIG. 4, the cross-sectional shape of the coil conductor 32 is an elliptical shape with the major axis orthogonal to the stacking direction. However, the cross-sectional shape of the coil conductor 32 is not particularly limited, and for example, it may be a rectangular shape in which the lengths of a pair of opposite sides in the stacking direction are the same, or a trapezoidal shape in which the lengths of a pair of opposite sides in the stacking direction are different.

[0052] A first recess 11a is provided on the first end face 11 of the stacked body 10 shown in FIG. 4. The first depression 11a is a macroscopic depression formed such that, among the first end faces 11 of the laminate 10, the portion overlapping the circumferential shape of the coil when the laminate 10 is viewed through in the length direction L bulges relatively, and the inner portion thereof is recessed relatively. Therefore, the first depression is different from the fine unevenness formed on the surface of the laminate. The same applies to the second depression described later.

[0053] The first depression 11a provided on the first end face 11 has the deepest part 11a1 inside the circumferential shape of the coil when the laminate 10 is viewed through in the length direction L. On the first end face 11 of the laminate 10, a first annular convex portion 11b that protrudes annularly so as to overlap the circumferential shape of the coil is provided in the direction opposite to the depth direction of the first depression 11a, that is, toward the outside of the laminate 10. Note that the depth d1 of the deepest part 11a1 of the first depression 11a is the length from the deepest part 11a1 of the first depression 11a in the length direction L to the apex 11b1 of the first annular convex portion 11b, which is the most protruding part of the first end face 11.

[0054] Here, the depth of the deepest part of the first depression on the first end face is measured by using a parallel dimension measurement tool or the like on a cross-sectional image obtained by using a digital microscope or the like for a cross-section exposed by polishing the laminate from the side surface (LT surface) of the laminate to the center in the width direction W, where the insulating layer is the lowest (the most recessed part) and the highest (the most protruding part, that is, corresponding to the apex of the first annular convex portion) in the length direction L.

[0055] Note that since the first annular convex portion 11b extends annularly corresponding to the circumferential shape of the coil, the apex 11b1 of the first annular convex portion 11b does not indicate the most protruding single point of the first annular convex portion, but indicates a ridge line that exists annularly at a position overlapping the circumferential shape of the coil. The entire region surrounded by the apex 11b1 of the first annular convex portion 11b corresponds to the first depression 11a.

[0056] The first annular convex portion is provided so as to overlap the circumferential shape of the coil, while the deepest part of the first depression is arranged inside the circumferential shape of the coil. Therefore, when the laminate is viewed through in the length direction L, it can be said that the first depression is arranged inside the first annular convex portion.

[0057] The first external electrode 21 is formed so as to cover the deepest part 11a1 of the first depression 11a and the apex 11b1 of the first annular convex portion 11b.

[0058] The first external electrode 21 shown in FIG. 4 covers the entire first end face 11 of the laminate 10 and a part of the first main face 13, the second main face 14, the first side face 15, and the second side face 16 extending from the first end face 11. However, in the laminated coil component of the present invention, the first external electrode only needs to cover at least a part of the first depression and a part of the surface that becomes the mounting surface on the first end face. For example, the first external electrode may be an L-shaped electrode that covers a part of the first end face and the surface (for example, the second main face) that extends from the first end face and becomes the mounting surface. Further, the first external electrode may be an oblique electrode that covers a part of the first end face, a part of the surface (for example, the second main face) that extends from the first end face and becomes the mounting surface, and a part of the first side face and the second side face that extend from the first end face and the mounting surface (for example, the second main face).

[0059] The first external electrode and the second external electrode may be resin electrode layers formed by applying and baking a conductive paste such as a paste containing Ag and glass frit on the first end face and the second end face of the laminate. When the first external electrode and the second external electrode are resin electrode layers, even when the substrate is bent after mounting, it is easy to relieve the stress transmitted from the substrate, and the connection reliability is excellent.

[0060] By the first external electrode 21 covering at least a part of the first depression 11a, while suppressing the first external electrode 21 from protruding outward, the thickness of the first external electrode 21 can be increased by the depth of the first depression 11a. Therefore, the current density can be reduced without significantly changing the external shape of the chip.

[0061] The first recess provided on the first end face of the laminate will be described with reference to FIGS. 5 and 6. 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. FIG. 6 is a schematic view of a state in which a part of the internal structure of the laminate shown in FIG. 5 is seen through as viewed from the first end face side. As shown in FIGS. 5 and 6, a first recess 11a is provided on the first end face 11 of the laminate 10. As shown in FIG. 6, the first recess 11a has a deepest part 11a1 inside the circumferential shape of the coil. Note that a part that is not the deepest part of the first recess 11a may overlap with the circumferential shape of the coil. As shown in FIGS. 5 and 6, a first annular convex portion 11b is provided on the first end face 11 of the laminate. As shown in FIG. 6, the first annular convex portion 11b is annular and is provided so as to overlap with the circumferential shape of the coil. When scanning the first annular convex portion 11b from the inside to the outside of the circumferential shape of the coil, the point where the distance from the deepest part 11a1 of the first recess 11a in the length direction L is the farthest is defined as the vertex 11b1 of the first annular convex portion 11b. The vertex 11b1 of the first annular convex portion 11b is annularly provided at a position overlapping with the circumferential shape of the coil.

[0062] 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 circumferential shape of the coil rising relatively when the laminate 10 is seen through in the length direction L and the part inside it being relatively recessed. Therefore, the first recess is different from the fine irregularities formed on the surface of the laminate. The same applies to the second recess described later.

[0063] It is preferable that the maximum thickness of the first external electrode is larger than the depth of the deepest part of the first recess. In the laminated coil component 1 shown in FIG. 4, the maximum thickness of the first external electrode 21 (the length indicated by the double-headed arrow t in FIG. 4) is larger than the depth d1 of the deepest part 11a1 of the first recess 11a. 12で shown length) is larger than the depth d1 of the deepest part 11a1 of the first recess 11a. Incidentally, the thickness of the first external electrode covering the deepest part of the first depression may be the maximum thickness of the first external electrode. In the multilayer coil component 1 shown in FIG. 4, the thickness t of the first external electrode 21 covering the deepest part 11a1 of the first depression 11a 12 is the maximum thickness of the first external electrode 21.

[0064] The first external electrode preferably covers the deepest part of the first depression. In the multilayer coil component 1 shown in FIG. 4, the first external electrode 21 covers the deepest part 11a1 of the first depression 11a on the first end face 11 of the laminate 10. When the first external electrode covers the deepest part of the first depression, the thickness of the first external electrode can be maximized without significantly changing the outer shape of the chip.

[0065] The first end face is provided with a first annular convex portion that is a portion protruding annularly. When the laminate is viewed through in the length direction, the first annular convex portion preferably overlaps the circumferential shape of the coil. In this case, the first external electrode preferably covers at least a part of the apex of the first annular convex portion on the first end face. Also at this time, the thickness of the first external electrode covering the deepest part of the first depression is preferably thicker than the thickness of the first external electrode covering at least a part of the apex of the first annular convex portion. When the thickness of the first external electrode covering the deepest part of the first depression is thicker than the thickness of the first external electrode covering the apex of the first annular convex portion, the first external electrode is formed so as to fill the first depression, and thus the effect of suppressing the current density is high.

[0066] In the multilayer coil component 1 shown in FIG. 4, on the first end face 11 of the laminate 10, at a position overlapping the circumferential shape (coil conductor 32) of the coil in the length direction L, a first annular convex portion 11b that is a portion where the first end face 11 protrudes annularly is provided. The first external electrode 21 covers all of the apex 11b1 of the first annular convex portion 11b. The thickness t of the first external electrode 21 covering the deepest part 11a1 of the first depression 11a 12is the thickness t of the first external electrode 21 that covers the vertex 11b1 of the first annular convex portion 11b 11 is larger.

[0067] It is preferable that the thickest part of the thickness of the first external electrode is provided at a position inside the circumferential shape of the coil, that is, at a position overlapping the first recess, when the laminate is viewed through from the length direction. In the laminated coil component 1 shown in FIG. 4, the position where the thickness of the first external electrode 21 is maximum is a position overlapping the deepest part 11a1 of the first recess 11a.

[0068] In the laminated coil component 1 shown in FIG. 4, although no recess is formed on the surface of the first external electrode 21 that covers the surface of the first end face 11 of the laminate 10, within a range that does not significantly change the external appearance shape of the chip, the shape of the first external electrode 21 that covers the surface of the first end face 11 of the laminate may be slightly recessed inward according to the first recess 11a, or conversely may be slightly swollen outward. For example, the first external electrode 21 that covers the surface of the first end face 11 of the laminate may have a recess that is similar to the first recess of the first end face 11 and shallower than the first recess. This occurs, for example, when the shape of the first external electrode that covers the first end face of the laminate follows the shape of the first end face 11 to a certain extent.

[0069] The depth of the deepest part of the first recess is preferably 30 μm or more and 50 μm or less. In the laminated coil component 1 shown in FIG. 4, the depth d1 of the deepest part 11a1 of the first recess 11a is preferably 30 μm or more and 50 μm or less. When the depth of the deepest part of the first recess is within the above range, even when forming the external electrode by the dip method, the mixing of air bubbles is suppressed, so that the formation defect of the external electrode can be suppressed.

[0070] The thickness of the first external electrode that covers the deepest part of the first recess is preferably 30 μm or more and 100 μm or less. Further, among the thickness of the first external electrode, the maximum thickness of the external electrode not covering the first depression is preferably 20% or more and 100% or less of the thickness of the external electrode covering the deepest part of the first depression.

[0071] The second end face and the second external electrode of the laminate may have the same structure as the first end face and the first external electrode of the laminate described above.

[0072] The second end face of the laminate may be provided with a second depression having a deepest part inside the circumferential shape of the coil when the laminate is viewed through in the length direction. A second depression 12a is provided on the second end face 12 of the laminate 10 shown in FIG. 4. The second depression 12a provided on the second end face 12 has a deepest part 12a1 inside the circumferential shape of the coil when the laminate 10 is viewed through in the length direction L.

[0073] On the second end face 12 of the laminate 10 shown in FIG. 4, a second annular convex portion 12b that protrudes annularly so as to overlap the circumferential shape of the coil is provided in the direction opposite to the depth direction of the second depression 12a, that is, toward the outside of the laminate 10. When the second annular convex portion 12b is scanned from the inside to the outside of the circumferential shape of the coil, the point where the distance from the second depression 12a in the length direction is the farthest is defined as the apex 12b1 of the second annular convex portion 12b. That is, the apex 12b1 of the second annular convex portion 12b is annularly provided at a position overlapping the circumferential shape of the coil. Therefore, the length from the deepest part 12a1 of the second depression 12a to the apex 12b1 of the second annular convex portion 12b in the length direction L is the depth d2 of the deepest part 12a1 of the second depression 12a.

[0074] The second external electrode 22 is formed so as to cover the deepest part 12a1 of the second depression 12a and the apex 12b1 of the second annular convex portion 12b.

[0075] The second end face is provided with a second annular convex portion that is a portion protruding annularly, and when the laminate is viewed through in the length direction L, the second annular convex portion preferably overlaps the circumferential shape of the coil. In this case, it is preferable that the second external electrode covers at least a part of the apex of the second annular convex portion among the second end faces. Also at this time, it is preferable that the thickness of the second external electrode covering the deepest part of the second depression is thicker than the thickness of the second external electrode covering at least a part of the apex of the second annular convex portion.

[0076] The depth d2 of the deepest part 12a1 of the second depression 12a is preferably 30 μm or more and 50 μm or less.

[0077] FIG. 7 is a diagram showing the simulation results of the current density of the external electrode when depressions are provided on the first end face and the second end face, respectively, and FIG. 8 is a diagram showing the simulation results of the current density of the external electrode when no depressions are provided on the first end face and the second end face.

[0078] In the simulation shown in FIG. 7, in a laminated coil component of 2012 size (L×W×T = 2.0 mm×1.25 mm×1.25 mm), depressions (first depression and second depression) with a depth of 30 μm at the deepest part are provided on the first end face and the second end face of the laminate, and an external electrode with a thickness of 40 μm is formed. The maximum thickness of the first external electrode covering the deepest part of the first depression is 70 μm, and the thickness of the first external electrode covering the part other than the first depression on the first end face is 40 μm. Also, the maximum thickness of the second external electrode covering the deepest part of the second depression is 70 μm, and the thickness of the second external electrode covering the part other than the second depression on the second end face is 40 μm.

[0079] In the simulation shown in FIG. 8, the shape of the laminate is changed from the state of FIG. 7 to a state where no first depression and second depression are formed. That is, no first depression and second depression are provided on the first end face and the second end face of the laminate, 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 locations.

[0080] In FIG. 8, the maximum value of the current density is 55.1 MA / m 2On the other hand, in FIG. 6, it was confirmed that the maximum value of the current density can be reduced to 47.4 MA / m 2 Thus, it was confirmed that the maximum value of the current density can be reduced to 47.4 MA / m. Therefore, it was found that the laminated coil component of the present invention can reduce the current density without significantly changing the external shape.

[0081] Hereinafter, an example of a method for manufacturing the laminated coil component of the present invention will be described.

[0082] <Production Process of Magnetic Material> First, Fe2O3, ZnO, CuO, and NiO are weighed so as to have a predetermined ratio.

[0083] Next, these weighed materials, pure water, etc. are put into a ball mill together with PSZ (partially stabilized zirconia) media and mixed, and then pulverized. The mixing and pulverizing time is, for example, 4 hours or more and 8 hours or less.

[0084] Then, the obtained pulverized material is dried and then calcined. The calcination temperature is, for example, 700°C or more and 800°C or less. The calcination time is, for example, 2 hours or more and 5 hours or less.

[0085] In this way, a powdery magnetic material, more specifically, a powdery magnetic ferrite material is produced.

[0086] The ferrite material is preferably a Ni-Cu-Zn-based ferrite material.

[0087] When the total amount of the Ni-Cu-Zn-based ferrite material is 100 mol%, it preferably contains Fe in terms of Fe2O3 of 40 mol% or more and 49.5 mol% or less, Zn in terms of ZnO of 2 mol% or more and 35 mol% or less, Cu in terms of CuO of 6 mol% or more and 13 mol% or less, and Ni in terms of NiO of 10 mol% or more and 45 mol% or less.

[0088] The Ni-Cu-Zn-based ferrite material may further contain additives such as Co, Bi, Sn, and Mn.

[0089] The Ni-Cu-Zn ferrite material may further contain inevitable impurities.

[0090] <Manufacturing process of ceramic green sheet> First, a magnetic material, an organic binder such as polyvinyl butyral resin, an organic solvent such as ethanol and toluene, and a plasticizer are put into a ball mill together with PSZ media and mixed, and then pulverized to produce a slurry.

[0091] Next, the slurry is formed into a sheet with a predetermined thickness by the doctor blade method or the like, and then punched into a predetermined shape to produce a ceramic green sheet. The thickness of the ceramic green sheet is, for example, 20 μm or more and 30 μm or less. The shape of the ceramic green sheet is, for example, rectangular.

[0092] As the material of the ceramic green sheet, instead of the magnetic material, a non-magnetic material such as a borosilicate glass material may be used, or a mixed material of the magnetic material and the non-magnetic material may be used.

[0093] <Forming process of conductor pattern> First, laser irradiation is performed on a predetermined portion of the ceramic green sheet to form via holes.

[0094] Next, a conductive paste such as an Ag paste is applied to the surface of the ceramic green sheet while filling the via holes by a screen printing method or the like. Thereby, a conductor pattern for via conductors is formed in the via holes in the ceramic green sheet, and a conductor pattern for coil conductors connected to the conductor pattern for via conductors is formed on the surface. In this way, a coil sheet in which a conductor pattern for coil conductors and a conductor pattern for via conductors are formed on the ceramic green sheet is produced. In the coil sheet, a conductor pattern for coil conductors corresponding to the coil conductor 32 shown in FIG. 2 and a conductor pattern for via conductors corresponding to the via conductors 33 (excluding the via conductors 33e and 33f) shown in FIG. 2 are formed. Further, separately from the coil sheet, a via sheet in which a conductor pattern for via conductors corresponding to the via conductors 33e and 33f shown in FIG. 2 is formed is produced.

[0095] <Manufacturing process of the laminated body block> After laminating the coil sheet and the via sheet in the order corresponding to FIG. 2 in the lamination direction (length direction L), a laminated body block is produced by thermocompression bonding. 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 that become the first end face and the second end face of the laminated body.

[0096] The method of forming the first recess on the surface that becomes the first end face of the laminated body is not particularly limited. For example, after laminating the coil sheet and the via sheet to produce a laminated sheet, when performing thermocompression bonding, a convex portion corresponding to the first recess is formed on the surface of the press die that contacts the upper surface of the laminated sheet. Similarly, the method of forming the second recess on the surface that becomes the second end face of the laminated body is not particularly limited. For example, after laminating the coil sheet and the via sheet to produce a laminated sheet, when performing thermocompression bonding, a convex portion corresponding to the second recess is formed on the surface of the pedestal (press die) that contacts the bottom surface of the laminated sheet.

[0097] Therefore, when thermocompression bonding the laminated sheet, by forming convex portions on the surface of the press die that contacts the upper surface of the laminated sheet and on the surface of the pedestal (press die) that contacts the bottom surface of the laminated sheet, respectively, a laminate can be manufactured in which a first recess and a second recess are formed in the first end face and the second end face, respectively.

[0098] As shown in FIG. 2, since the first end face and the second end face of the laminate are opposite to each other in the stacking direction of the insulating layer, the shape of the surface of the press die that contacts the upper surface or the bottom surface of the laminated sheet when thermocompression bonding the laminated sheet is reflected in the shape of the first end face of the laminate.

[0099] The position and depth of the first recess and the position and depth of the second recess can be appropriately adjusted according to the shape of the convex portion provided on the surface of the die. Note that the shape of the press die itself may be a shape having the above-described convex portion. However, while using a press die with a flat pressing surface, when pressing the laminated sheet, a member having a shape corresponding to the above convex portion may be sandwiched between the press die and the laminated sheet.

[0100] In addition to the method of using the press die described above, by adjusting the thickness, number of layers, etc. of the via sheet and coil sheet, or by changing the thermocompression bonding conditions, a first recess may be formed in the first end face of the laminate in some cases.

[0101] <Manufacturing Process of Laminate and Coil> First, a chip that has been individualized is produced by cutting a laminate block into a predetermined size using a dicing machine or the like.

[0102] Next, the individualized 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 longer and 4 hours or shorter.

[0103] When the individualized chips are fired, the ceramic green sheets of the coil sheet and the via sheet become insulating layers.

[0104] Further, when the fragmented chips are fired, the conductor pattern for the coil conductor and the conductor pattern for the via conductor each become the coil conductor and the via conductor. As a result, a coil is produced in which a plurality of coil conductors laminated together with the insulating layer are electrically connected via the via conductor.

[0105] As described above, a plurality of insulating layers are laminated in the lamination direction to produce a laminate having a coil built therein.

[0106] For the laminate, for example, barrel polishing may be performed to round the corners and ridge lines.

[0107] <External electrode forming step> First, a conductive paste layer is formed by applying a conductive paste such as a paste containing Ag and glass frit to the first end face and the second end face from which the coil is drawn out of the outer surface of the laminate. As a method of applying the conductive paste, a conventionally known method, for example, a dip method or a method of applying the conductive paste with a brush can be used.

[0108] Next, the base electrode of the external electrode is formed by baking the conductive paste layer. The baking temperature is, for example, 800 °C or higher and 820 °C or lower. The thickness of the base electrode is, for example, 5 μm.

[0109] Then, an Ni plating electrode and an Sn plating electrode are sequentially formed on the surface of the base electrode by electrolytic plating or the like. Thereby, an external electrode having a base electrode, an Ni plating electrode, and an Sn plating electrode in this order is formed.

[0110] Since the first end face and the second end face of the laminate produced by the above procedure are each provided with a first recess and a second recess, the first external electrode and the second external electrode are formed so as to cover the first recess and the second recess, respectively, thereby manufacturing the laminated coil component of the present invention.

[0111] The following matters are described in this specification.

[0112] The present disclosure (1) includes a laminate in which a plurality of insulating layers are laminated and has 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 laminated together with the insulating layers. The laminate has a first end face and a second end face opposite to each other in the length direction, a first main face and a second main face opposite to each other in the height direction orthogonal to the length direction, and a first side face and a second side face opposite to 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. On the first end face, a first recess having a deepest part inside the circumferential shape of the coil is provided when the laminate is viewed through in the length direction. The first external electrode is a laminated coil component that covers at least a part of the first recess.

[0113] The present disclosure (2) is the laminated coil component according to the present disclosure (1), wherein the depth of the deepest part of the first recess is 30 μm or more and 50 μm or less.

[0114] The present disclosure (3) is the laminated coil component according to the present disclosure (1) or (2), wherein the maximum thickness of the first external electrode is larger than the depth of the deepest part of the first recess.

[0115] The present disclosure (4) is a laminated coil component in any combination with any one of the present disclosures (1) to (3), wherein the first external electrode covers the deepest part of the first recess.

[0116] On the first end face, a first annular convex part, which is a part protruding annularly, is provided. When the laminate is viewed through in the longitudinal direction, the first annular convex portion overlaps with the circumferential shape of the coil. The first external electrode covers at least a part of the apex of the first annular convex portion among the first end faces. 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 apex of the first annular convex portion. The laminated coil component according to the present disclosure (4).

[0117] In the present disclosure (6), a second recess having a deepest part inside the circumferential shape of the coil is provided on the second end face when the laminate is viewed through in the longitudinal direction. The second external electrode covers at least a part of the second recess. The laminated coil component is an arbitrary combination of any one of the present disclosures (1) to (5).

Explanation of reference numerals

[0118] 1 Laminated coil component 10 Laminate 11 First end face 11a First recess 11a1 Deepest part of the first recess 11b First annular convex portion 11b1 Apex of the first annular convex portion 12 Second end face 12a Second recess 12a1 Deepest part of the second recess 12b Second annular convex portion 12b1 Apex of the second annular convex portion 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 layer 32, 32a, 32b, 32c, 32d Coil conductor 33, 33a, 33b, 33c, 33d, 33e, 33f via conductors 34, 34a, 34b, 34c, 34d circumferential parts 35, 35a, 35b, 35c, 35d, 35e, 35f lands 41 first lead-out conductor 42 second lead-out conductor A coil axis of the coil d1 depth of the deepest part of the first depression d2 depth of the deepest part of the second depression t 11 Thickness of the first external electrode covering the apex of the first annular convex part t 12 Thickness of the first external electrode covering the deepest part of the first depression t 21 Thickness of the second external electrode covering the apex of the second annular convex part t 22 Thickness of the second external electrode covering the deepest part of the second depression

Claims

1. A laminated body in which a plurality of insulating layers are laminated and which has 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 laminated together with the insulating layer, The laminated 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 depression having a deepest part inside the circumferential shape of the coil is provided on the first end face when the laminated body is viewed through in the length direction, The first external electrode covers at least a part of the first depression, a laminated coil component.

2. The depth of the deepest part of the first depression is 30 μm or more and 50 μm or less, the laminated coil component according to claim 1.

3. The maximum thickness of the first external electrode is larger than the depth of the deepest part of the first depression, the laminated coil component according to claim 1 or 2.

4. The first external electrode covers the deepest part of the first depression, the laminated coil component according to claim 1 or 2.

5. A first annular convex part which is a part protruding annularly is provided on the first end face, When the laminated body is viewed through in the length direction, the first annular convex part overlaps the circumferential shape of the coil, The first external electrode covers at least a part of the apex of the first annular convex part of the first end face, The thickness of the first external electrode covering the deepest part of the first depression is thicker than the thickness of the first external electrode covering at least a part of the apex of the first annular convex part, the laminated coil component according to claim 4.

6. A second depression having a deepest part inside the circumferential shape of the coil is provided on the second end face when the laminated body is viewed through in the length direction, The second external electrode covers at least a part of the second depression, the laminated coil component according to claim 1.

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