Laminated inductor

Abstract

The invention provides a laminated inductor capable of improving an inductance value and a Q value. The laminated inductor includes: a body having a first end surface and a second end surface facing each other in a first direction; a first external electrode provided on the first end surface; a second external electrode provided on the second end surface; an inner conductor provided inside the body and wound in a coil axis direction orthogonal to the first direction; a first lead-out conductor which is provided inside the green body and connects the internal conductor and the first external electrode; and a second lead-out conductor provided inside the body and connecting the inner conductor and the second external electrode, the second lead-out conductor being electrically connected to the second external electrode when viewed from the coil axis direction. A straight line extending in the first direction as a first boundary portion of the boundary between the first lead-out conductor and the inner conductor does not overlap with a second boundary portion of the boundary between the second lead-out conductor and the inner conductor. The second lead-out conductor has a curved shape protruding in a direction away from a straight line formed by extending the first boundary portion in the first direction.

Description

Technical Field

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

[0002] Patent document 1 describes a stacked chip common-mode choke coil, in which a plurality of magnetic sheets having conductor patterns formed on their surfaces are stacked, the conductor patterns being connected by vias to form a pair of coils, and the ends of each coil being extended to different positions on the outer edge of the side of the magnetic sheet to form lead-out electrodes. The stacked chip common-mode choke coil is characterized in that the lead-out electrodes of each coil are formed widely at the side ends.

[0003] Patent Document 2 describes a stacked inductor in which electrical insulating layers and conductor patterns are alternately stacked, the ends of the conductor patterns being sequentially connected to form coils overlapping in the stacking direction within the electrical insulating layer body, and the ends of the coils being connected to external electrodes via lead conductors, respectively, and mounted on a substrate. This stacked inductor is characterized in that the length of the lead conductors is increased or decreased depending on the height of the lead conductors above the substrate, and the inductance values from the substrate to the lead conductors are matched to each other.

[0004] Patent document 3 describes a stacked chip inductor characterized in that a spiral coil is provided inside a magnetic body, and a lead portion connecting the coil to an external terminal electrode formed on the end face of the chip and a spiral winding pattern constituting the coil are independently provided near the surface of the chip, and the lead portion is conductively connected to the starting and ending ends of the coil through a columnar, thinner electrode layer.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 5-190364

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2001-126923

[0007] Patent Document 3: Japanese Utility Model Application Laid-Open No. 5-69915

[0008] In Patent Document 1 Figure 7 The common mode choke coil shown in the patent document 2 Figure 1 In the stacked inductor shown in (b), the lead conductors on both sides extend from the same straight line of the coil when viewed from the coil axis. Arranging the lead conductors so that they extend from the same straight line of the coil reduces the degree of flexibility in the placement of the connection between the lead conductors and the inner conductor. Consequently, it is difficult to adjust electrical characteristics such as inductance by adjusting the placement of the connection between the lead conductors and the inner conductor.

[0009] In addition, in Patent Document 3 Figure 5In the illustrated multilayer chip inductor, when viewed from the coil axis, one lead conductor extends in the same direction as the inner conductor's winding direction (the direction the coil winds around), while the other extends in the opposite direction. When the lead conductor extends in the opposite direction to the inner conductor's winding direction, the direction of current flow changes dramatically at the connection between the lead conductor and the inner conductor. Consequently, there is a risk of deteriorating electrical characteristics, such as the Q value (Q = 2πfL / R) (L: inductance, R: resistance, f: frequency). Summary of the Invention

[0010] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a multilayer inductor capable of improving inductance and Q value.

[0011] A laminated inductor according to the present invention is characterized by comprising: a base body having a first end face and a second end face facing each other in a first direction; a first external electrode provided on the first end face; a second external electrode provided on the second end face; an internal conductor provided inside the base body and wound along a coil axis direction perpendicular to the first direction; a first lead conductor provided inside the base body and connecting the internal conductor to the first external electrode; and a second lead conductor provided inside the base body and connecting the internal conductor to the second external electrode, wherein, when viewed from the coil axis, a straight line extending along the first direction along a first boundary portion does not overlap with a second boundary portion, and the second lead conductor has a curved shape that convexly extends away from the straight line extending along the first boundary portion, wherein the first boundary portion is a boundary between the first lead conductor and the internal conductor, and the second boundary portion is a boundary between the second lead conductor and the internal conductor.

[0012] According to the present invention, a laminated inductor capable of improving inductance and Q value can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic perspective view showing an example of a laminated inductor according to the first embodiment of the present invention.

[0014] Figure 2 yes Figure 1 An example of an exploded perspective view of a laminated inductor is shown.

[0015] Figure 3 Is the perspective along the coil axis Figure 1 The stacked inductor shown in FIG.

[0016] Figure 4 Schematic diagram showing an example of the first boundary portion.

[0017] Figure 5 is a schematic diagram showing another example of the first boundary portion.

[0018] Figure 6 This is a diagram showing a laminated inductor according to a second embodiment of the present invention, viewed from a perspective along the coil axis.

[0019] Figure 7 This is a diagram showing a laminated inductor according to a third embodiment of the present invention, viewed from a perspective along the coil axis.

[0020] Figure 8 This is a diagram showing a laminated inductor according to a fourth embodiment of the present invention, viewed from a perspective along the coil axis.

[0021] Figure 9 It is a schematic perspective view showing an example of a laminated inductor according to a fifth embodiment of the present invention.

[0022] Figure 10 yes Figure 9 An example of an exploded perspective view of a laminated inductor is shown.

[0023] Figure 11 yes Figure 1 Another example of an exploded perspective view of a stacked inductor is shown.

[0024] Explanation of Reference Numerals: 1, 2, 3, 4, 5…laminated inductor; 10…body; 11…first end surface; 12…second end surface; 13…first side surface; 14…second side surface; 15…first principal surface; 16…second principal surface; 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, 17i…insulating layer; 21…first external electrode; 22…second external electrode; 30…inner conductor; 31…coil conductor; 32…connecting conductor; 41…first lead conductor; 42…second lead conductor; 51…first boundary portion; 52…second boundary portion; 61…first via-hole conductor; 62…second via-hole conductor; D1…first direction; D2…second direction; D3…third direction; C…coil axis direction DETAILED DESCRIPTION

[0025] The following describes the laminated inductor of the present invention. The present invention is not limited to the following configurations and can be modified as appropriate without departing from the spirit of the present invention. Furthermore, combinations of multiple preferred configurations described below also constitute the present invention.

[0026] The following embodiments are merely illustrative, and it is naturally possible to partially substitute or combine the components shown in different embodiments. From the second embodiment onwards, details common to the first embodiment are omitted, and the description will focus on the differences. In particular, the same functions and effects resulting from the same components will not be mentioned sequentially in each embodiment.

[0027] In the following description, when there is no particular distinction between the embodiments, each embodiment will be referred to simply as a "laminated inductor of the present invention."

[0028] The drawings shown below are schematic diagrams, and their dimensions, aspect ratios, and other aspects may differ from those of actual products.

[0029] In this specification, terms indicating the relationship between elements (for example, "parallel," "perpendicular," "orthogonal," etc.) and terms indicating the shape of an element mean not only the precise manner as described in the text, but also a substantially equivalent range, for example, a range containing a difference of several percent.

[0030] [First embodiment]

[0031] Hereinafter, an example of the laminated inductor of the present invention will be described as a laminated inductor according to a first embodiment of the present invention.

[0032] Figure 1 This is a schematic perspective view showing an example of a laminated inductor according to the first embodiment of the present invention.

[0033] Figure 1 The illustrated multilayer inductor 1 includes an element 10 , a first external electrode 21 , and a second external electrode 22 .

[0034] In this manual, if Figure 1 As shown in FIG. 1 , the first direction, the second direction, and the third direction are defined by D1, D2, and D3, respectively. Here, the first direction D1, the second direction D2, and the third direction D3 are orthogonal to each other.

[0035] like Figure 1 As shown, in the stacked inductor 1, the surface of the body 10 includes a first end face 11 and a second end face 12 facing each other in a first direction D1, a first side face 13 and a second side face 14 facing each other in a second direction D2, and a first main face 15 and a second main face 16 facing each other in a third direction D3.

[0036] The first end face 11 and the second end face 12 of the blank 10 do not need to be strictly perpendicular to the first direction D1. Furthermore, the first side face 13 and the second side face 14 of the blank 10 do not need to be strictly perpendicular to the second direction D2. Furthermore, the first principal face 15 and the second principal face 16 of the blank 10 do not need to be strictly perpendicular to the third direction D3.

[0037] like Figure 1 As shown, the blank 10 is, for example, in the shape of a rectangular parallelepiped.

[0038] In this specification, a rectangular parallelepiped shape may be a shape that can be basically called a rectangular parallelepiped, and for example, a substantially rectangular parallelepiped shape including rounded corners and ridges as described later.

[0039] It is preferable that the corners and ridges of the blank 10 are rounded. The corners of the blank 10 are the portions where three surfaces of the blank 10 intersect. The ridges of the blank 10 are the portions where two surfaces of the blank 10 intersect.

[0040] The first external electrode 21 is provided on the first end surface 11 of the green body 10. Figure 1 In the example shown, the first external electrode 21 is provided on a portion of the first end surface 11 of the green body 10 , but the first external electrode 21 may be provided on the entire first end surface 11 of the green body 10 .

[0041] exist Figure 1 In the example shown, the first external electrode 21 extends from the first end surface 11 to the first main surface 15. The first external electrode 21 is exposed on a portion of the first end surface 11 and a portion of the first main surface 15 of the green body 10. The first external electrode 21 may be provided only on the first end surface 11.

[0042] The second external electrode 22 is provided on the second end surface 12 of the green body 10. Figure 1 In the example shown, the second external electrode 22 is provided on a portion of the second end surface 12 of the green body 10 , but the second external electrode 22 may be provided on the entire second end surface 12 of the green body 10 .

[0043] exist Figure 1 In the example shown, the second external electrode 22 extends from the second end surface 12 to the first main surface 15. The second external electrode 22 is exposed on a portion of the second end surface 12 and a portion of the first main surface 15 of the green body 10. The second external electrode 22 may be provided only on the second end surface 12.

[0044] In the multilayer inductor 1 , the first principal surface 15 of the base body 10 is a mounting surface. More specifically, the first principal surface 15 of the base body 10 is a mounting surface that faces a mounting object (eg, a substrate) when the multilayer inductor 1 is mounted.

[0045] When the first external electrode 21 and the second external electrode 22 are exposed on the first principal surface 15 of the element 10 , which serves as the mounting surface, the mountability of the multilayer inductor 1 is easily improved.

[0046] Figure 2 yes Figure 1 An example of an exploded perspective view of a laminated inductor is shown.

[0047] The green body 10 includes an insulator. The insulator is formed by stacking a plurality of insulating layers in the coil axis direction C. The coil axis direction C is a direction parallel to the stacking direction of the green body 10. Figure 2 In the illustrated example, the coil axis direction C is a direction parallel to the third direction D3 and a direction perpendicular to the first direction D1 and the second direction D2.

[0048] exist Figure 2 In the illustrated example, the plurality of insulating layers include insulating layer 17a, insulating layer 17b, insulating layer 17c, insulating layer 17d, insulating layer 17e, insulating layer 17f, insulating layer 17g, insulating layer 17h, and insulating layer 17i. Insulating layers 17a, 17b, 17c, 17d, 17e, 17f, 17g, 17h, and 17i are stacked in order from first principal surface 15 toward second principal surface 16 of base body 10 in coil axis direction C.

[0049] Furthermore, a plurality of insulating layers may be integrated, and the boundaries between these insulating layers may not be clearly visible.

[0050] Examples of insulating materials constituting the insulator (insulating layer) include glass materials primarily composed of borosilicate glass, ceramic materials, organic materials such as epoxy resins, fluororesins, and polymer resins, and composite materials such as glass epoxy resins. Insulating materials having low dielectric constants and dielectric loss are particularly preferred.

[0051] The insulating materials constituting the plurality of insulating layers may be the same as or different from each other, or may be partially different from each other.

[0052] The dimensions of the plurality of insulating layers in the coil axis direction C may be the same as or different from each other, or may be partially different from each other.

[0053] The multilayer inductor 1 further includes an inner conductor 30 , a first lead conductor 41 , and a second lead conductor 42 .

[0054] The internal conductor 30 is provided inside the base body 10 and is wound along the coil axis direction C that is perpendicular to the first direction D1 .

[0055] Figure 2 The illustrated laminated inductor 1 has a so-called longitudinally wound structure. Specifically, in laminated inductor 1, the coil axis direction C is perpendicular to first principal surface 15, the mounting surface of base body 10. First and second external electrodes 21, 22 extend to first principal surface 15, the mounting surface of longitudinally wound laminated inductor 1.

[0056] exist Figure 2 In the illustrated example, the internal conductor 30 includes a plurality of coil conductors 31 and a plurality of connection conductors 32 .

[0057] The plurality of coil conductors 31 are electrically connected via the plurality of connection conductors 32 , thereby constituting a solenoid-shaped coil built into the base body 10 .

[0058] exist Figure 2 In the example shown, coil conductors 31 are provided in each of insulating layers 17c, 17d, 17e, 17f, and 17g. Furthermore, connecting conductors 32 are provided in each of insulating layers 17d, 17e, 17f, and 17g. Each connecting conductor 32 is provided so as to penetrate each insulating layer.

[0059] Examples of the conductive material constituting the coil conductor 31 include Ag, Au, Cu, Pd, Ni, Al, and alloys containing at least one of these metals.

[0060] The conductive materials constituting the plurality of coil conductors 31 may be the same as or different from each other, or may be partially different from each other.

[0061] The dimensions of the coil conductors 31 in the coil axis direction C, in other words, the thicknesses of the coil conductors 31 may be the same as or different from each other, or may be partially different from each other.

[0062] The dimensions of the plurality of coil conductors 31 in a direction perpendicular to the direction in which the coil conductors 31 extend when viewed from the coil axis direction C, in other words, the widths of the coil conductors 31 , may be the same as, different from, or partially different from each other.

[0063] When viewed from the coil axis direction C, the coil conductors 31 preferably overlap with each other.

[0064] When viewed from the coil axis direction C, the internal conductor 30 may be a shape consisting of only straight portions, a shape consisting of only curved portions, or a shape consisting of both straight portions and curved portions. For example, when viewed from the coil axis direction C, the internal conductor 30 may be a circular shape, an elliptical shape, an oblong shape, or a polygonal shape. Figure 2 In the example shown, when viewed from the coil axis direction C, the shape of the internal conductor 30 is an oval shape.

[0065] Examples of the conductive material constituting the connection conductor 32 include Ag, Au, Cu, Pd, Ni, Al, and alloys containing at least one of these metals.

[0066] The conductive materials constituting the plurality of connection conductors 32 may be the same as or different from each other, or may be partially different from each other.

[0067] The conductive material constituting the connection conductor 32 may be the same as or different from the conductive material constituting the coil conductor 31 .

[0068] The first lead conductor 41 is provided inside the base body 10 and connects the internal conductor 30 to the first external electrode 21. Figure 2 In the illustrated example, the first lead conductor 41 is provided on the insulating layer 17 b .

[0069] The second lead conductor 42 is provided inside the body 10 and connects the internal conductor 30 to the second external electrode 22. Figure 2 In the illustrated example, the second lead conductor 42 is provided on the insulating layer 17h.

[0070] exist Figure 2 In the illustrated laminated inductor 1 , the first lead conductor 41 , the inner conductor 30 , and the second lead conductor 42 are stacked in this order from one side toward the other in the coil axis direction C. Specifically, the first lead conductor 41 , the inner conductor 30 , and the second lead conductor 42 are stacked in this order from the first principal surface 15 side toward the second principal surface 16 side of the base body 10 .

[0071] The inner conductor 30 and the first lead conductor 41 are connected via the first via-hole conductor 61 , and the inner conductor 30 and the second lead conductor 42 are connected via the second via-hole conductor 62 .

[0072] When the first lead conductor 41 is connected to the internal conductor 30 via the first via-hole conductor 61, the distance between the first lead conductor 41 and the internal conductor 30 is increased, thereby preventing short circuits and improving reliability. Furthermore, magnetic flux blocking can be suppressed, thereby improving inductance and Q value.

[0073] Similarly, if the second lead conductor 42 is connected to the internal conductor 30 via the second via-hole conductor 62, the distance between the second lead conductor 42 and the internal conductor 30 is increased, thereby preventing short circuits and improving reliability. In addition, the magnetic flux can be suppressed, thereby improving the inductance value and Q value.

[0074] The first via-hole conductor 61 may be provided to penetrate one insulating layer or multiple insulating layers. Similarly, the second via-hole conductor 62 may be provided to penetrate one insulating layer or multiple insulating layers.

[0075] Although not shown, the first lead conductor 41 and the internal conductor 30 may be connected without a via conductor. That is, the first lead conductor 41 and the internal conductor 30 may be present on the same insulating layer and directly connected.

[0076] Although not shown, the second lead conductor 42 and the internal conductor 30 may be connected without a via conductor. In other words, the second lead conductor 42 and the internal conductor 30 may be present on the same insulating layer and directly connected.

[0077] Alternatively, one of the first lead conductor 41 and the second lead conductor 42 may be connected to the internal conductor 30 via a via-hole conductor, while the other may be connected to the internal conductor 30 without a via-hole conductor.

[0078] Figure 3 Is the perspective along the coil axis Figure 1 The stacked inductor shown in FIG.

[0079] The first boundary portion 51 is a boundary between the first lead conductor 41 and the internal conductor 30. The definition of the first boundary portion 51 will be described later.

[0080] The second boundary portion 52 is a boundary between the second lead conductor 42 and the internal conductor 30. The definition of the second boundary portion 52 will be described later.

[0081] In the multilayer inductor 1 , when viewed from the coil axis, a straight line A extending the first boundary 51 in the first direction D1 does not overlap with the second boundary 52 between the second lead conductor 42 and the inner conductor 30 .

[0082] Unlike the case where the straight line A, obtained by extending the first boundary portion 51 along the first direction D1, overlaps with the second boundary portion 52, which serves as the boundary between the second lead conductor 42 and the inner conductor 30. In this case, the second boundary portion 52 does not need to overlap with the straight line A. This allows the arrangement of the second boundary portion 52, which serves as the connection between the second lead conductor 42 and the inner conductor 30, to be adjusted. This allows the length of the inner conductor 30 forming the coil to be adjusted. For example, the second boundary portion 52 can be arranged so that the length of the inner conductor 30 forming the coil is longer than when the second boundary portion 52 overlaps with the straight line A. This allows the inductance of the laminated inductor 1 to be increased.

[0083] Furthermore, in the multilayer inductor 1 , when viewed from the coil axis direction, the second lead conductor 42 has a curved shape that is convex in a direction away from a straight line A extending the first boundary portion 51 in the first direction D1 .

[0084] If the second lead conductor 42 has a curved shape that is convex in a direction away from the straight line A obtained by extending the first boundary portion 51 along the first direction D1, the change in the flow direction of the current at the second boundary portion 52 can be made gentle. Figure 3 Compared to the laminated inductor of the comparative example in which the second boundary portion 52 in the embodiment extends in a straight line parallel to the straight line A, Figure 3 In the multilayer inductor 1 shown, the change in the direction of current flow can be made gentle at the second boundary portion 52. Therefore, the second boundary portion 52 can suppress the obstruction of current flow, thereby improving the Q value of the multilayer inductor 1.

[0085] The curved portion of the second lead conductor 42 extending from the second boundary portion 52 only needs to protrude in a direction away from the straight line A obtained by extending the first boundary portion 51 along the first direction D1. The entire second lead conductor 42 does not need to protrude in a direction away from the straight line A obtained by extending the first boundary portion 51 along the first direction D1. For example, the second lead conductor 42 may include a first curved portion extending from the second boundary portion 52 and protruding in a direction away from the straight line A obtained by extending the first boundary portion 51 along the first direction D1, and a second curved portion extending from the first curved portion and not protruding in a direction away from the straight line A obtained by extending the first boundary portion 51 along the first direction D1. Alternatively, the second lead conductor 42 may include a curved portion extending from the second boundary portion 52 and protruding in a direction away from the straight line A obtained by extending the first boundary portion 51 along the first direction D1, and a straight portion extending from the curved portion.

[0086] Furthermore, when the first end face 11 and the second end face 12 are not strictly parallel and the first direction D1 cannot be strictly defined, the first direction D1 may be defined as follows: The first direction D1 may be defined as a direction in which a straight line extending through the first end face 11 and the second end face 12 does not overlap with the second boundary portion 52 and the second lead conductor 42 protrudes away from the straight line extending through the first boundary portion 51.

[0087] The first lead conductor 41 preferably has a straight shape when viewed from the coil axis direction C. If the first lead conductor 41 has a straight shape, the wiring is less prone to bending, and thus the Q value of the multilayer inductor 1 can be further improved.

[0088] exist Figure 3 In the example shown, the first lead conductor 41 has a linear shape and extends parallel to the first direction D1. However, the first lead conductor 41 may have a linear shape and not extend parallel to the first direction D1.

[0089] Preferably, the first lead conductor 41 has a straight shape when viewed from the coil axis direction C, and the first lead conductor 41 of the first lead conductor 41, the second lead conductor 42, and the internal conductor 30 is located closest to the first main surface 15. With this configuration, the area where the lead conductors face the external electrodes can be designed to be small, which can reduce stray capacitance and improve high-frequency characteristics.

[0090] Figure 4 Schematic diagram showing an example of the first boundary portion.

[0091] Figure 4 is with Figure 3 Similarly, the stacked inductor is viewed from the perspective of the coil axis. Figure 4 In order to simplify the description, only the inner conductor 30 and the first lead conductor 41 are shown. Figure 4 In the description, the definition of the first boundary portion 51 as the boundary between the first lead conductor 41 and the internal conductor 30 is taken as an example, but the second boundary portion 52 as the boundary between the second lead conductor 42 and the internal conductor 30 is also defined by the same definition.

[0092] When the laminated inductor is viewed through along the coil axis, the center line of the inner conductor 30 ( Figure 4 The line shown by M1 in FIG) and the center line of the first lead conductor 41 ( Figure 4 A cross section of the first lead conductor 41 at a point where the center line of the first lead conductor 41 is perpendicular to the center line of the first lead conductor 41 and where the line (indicated by line M2) overlaps is a first boundary portion 51.

[0093] Similarly, when the laminated inductor is viewed through along the coil axis, a cross section of the second lead conductor 42 perpendicular to the center line of the second lead conductor 42 at a point where the center lines of the inner conductor 30 and the second lead conductor 42 overlap is a second boundary portion 52 .

[0094] The center lines of the inner conductor 30 , the first lead conductor 41 , and the second lead conductor 42 are lines passing through the centers of the widths of the inner conductor 30 , the first lead conductor 41 , and the second lead conductor 42 , respectively.

[0095] The first boundary portion 51 has the same width as the first lead conductor 41 , so a straight line A obtained by extending the first boundary portion 51 in the first direction D1 is substantially strip-shaped.

[0096] like Figure 3 As shown, when a pad is present on first boundary portion 51 and the width of first boundary portion 51 is greater than the width of other portions of first lead conductor 41, the width of first boundary portion 51 may be determined assuming that no pad exists. In other words, the width of first boundary portion 51 may be set to the same width as the width of the portion of first lead conductor 41 excluding the pad.

[0097] Figure 5 is a schematic diagram showing another example of the first boundary portion.

[0098] exist Figure 5 In the embodiment, the first lead conductor 41 is connected to the curved portion of the inner conductor 30. When the curved portion of the inner conductor 30 is connected to the first lead conductor 41, the curved portion is also connected to the center line ( Figure 5 The line shown by M1 in FIG) and the center line of the first lead conductor 41 ( Figure 5 A cross section of the first lead conductor 41 at a point where the center line of the first lead conductor 41 is perpendicular to the center line of the first lead conductor 41 and where the line (indicated by line M2) overlaps is a first boundary portion 51.

[0099] [Second embodiment]

[0100] Figure 6 This is a diagram showing a laminated inductor according to a second embodiment of the present invention, viewed from a perspective along the coil axis.

[0101] In the multilayer inductor 2 , the first side surface 13 and the second side surface 14 face each other in the second direction D2 perpendicular to the first direction D1 and the coil axis direction, similarly to the multilayer inductor 1 .

[0102] like Figure 6As shown, in the laminated inductor 2, when viewed from the coil axis, the first boundary portion 51 is located closer to the first side face 13 than the center of the base body 10, and the second boundary portion 52 is located closer to the second side face 14 than the center of the base body 10. In this case, the length of the inner conductor 30 forming the coil can be further extended, thereby further increasing the inductance value of the laminated inductor 2.

[0103] When a straight line passing through the center of gravity of the blank 10 when viewed from the coil axis direction and parallel to the first direction D1 is defined as the center line of the blank 10 ( Figure 6 If the first boundary portion 51 is located closer to the first side 13 than the center line CL of the base body 10, then the first boundary portion 51 can be said to be located closer to the first side 13 than the center line CL of the base body 10. Similarly, if the second boundary portion 52 is located closer to the second side 14 than the center line CL of the base body 10, then the second boundary portion 52 can be said to be located closer to the second side 14 than the center line CL of the base body 10. The center of gravity referred to here refers to the geometric center of gravity without considering the specific gravity of the base body 10, the internal conductor 30, and other components.

[0104] [Third embodiment]

[0105] Figure 7 This is a diagram showing a laminated inductor according to a third embodiment of the present invention, viewed from a perspective along the coil axis.

[0106] like Figure 7 As shown, in the laminated inductor 3, when viewed from the coil axis, the second lead conductor 42 extends at the second boundary portion 52 in a tangential direction along the second boundary portion 52 of the loop path of the inner conductor 30. In this case, the change in current direction becomes more gradual, and the Q value can be further improved.

[0107] Preferably, the first lead conductor 41 also extends at the first boundary portion 51 in a tangential direction of the inner conductor 30 at the first boundary portion 51. In this case, the change in the current direction becomes more gradual, and the Q value can be further improved.

[0108] The tangent line at the first boundary portion 51 of the circumferential path of the inner conductor 30 ( Figure 7 The line L1 in FIG. 5 is a tangent line to the centerline of the inner conductor 30 at the first boundary portion 51 when viewed from the coil axis. Specifically, at the first boundary portion 51, a straight line extending in the direction in which the centerline of the inner conductor 30 extends becomes the tangent line L1 to the inner conductor 30's circumferential path at the first boundary portion 51.

[0109] Similarly, the tangent line ( Figure 7The line L2 in FIG. 5 is a tangent line to the centerline of the inner conductor 30 at the second boundary portion 52 when viewed from the coil axis. Specifically, at the second boundary portion 52, a straight line extending in the direction in which the centerline of the inner conductor 30 extends is the tangent line L2 to the inner conductor 30's circumferential path at the second boundary portion 52.

[0110] The center line of the inner conductor 30 is a line passing through the center of the width of the inner conductor 30 .

[0111] [Fourth embodiment]

[0112] Figure 8 This is a diagram showing a laminated inductor according to a fourth embodiment of the present invention, viewed from a perspective along the coil axis.

[0113] like Figure 8 As shown, in the laminated inductor 4, the second lead conductor 42 is connected to the second external electrode 22 at a position perpendicular to the second external electrode 22 at the connection portion thereof when viewed from the coil axis. In this case, current concentration at the connection portion between the second external electrode 22 and the second lead conductor 42 can be suppressed, thereby further improving the Q value.

[0114] When viewed from the coil axis, the second lead conductor 42 does not need to be strictly perpendicular to the second external electrode 22 at the portion where it is connected to the second external electrode 22. For example, if the angle between the second lead conductor 42 and the second external electrode 22 deviates from the perpendicular by less than 5°, the second lead conductor 42 can be said to be perpendicular to the second external electrode 22 at the portion where it is connected to the second external electrode 22.

[0115] Furthermore, when viewed from the coil axis, the first lead conductor 41 is preferably connected to the first external electrode 21 at a portion thereof connected thereto at right angles to the first external electrode 21. For example, if the angle between the first lead conductor 41 and the first external electrode 21 is within 5° of the vertical angle, the first lead conductor 41 can be said to be connected to the first external electrode 21 at a portion thereof at right angles to the first external electrode 21.

[0116] [Fifth embodiment]

[0117] Figure 9 It is a schematic perspective view showing an example of a laminated inductor according to a fifth embodiment of the present invention.

[0118] Figure 10 yes Figure 9 An example of an exploded perspective view of a laminated inductor is shown.

[0119] exist Figure 9 as well as Figure 10In the illustrated stacked inductor 5, the body 10 has a first side surface 13 and a second side surface 14 facing each other in a second direction D2 that is orthogonal to the first direction D1 and the coil axis direction C. The first external electrode 21 extends from the first end surface 11 to the first side surface 13, and the second external electrode 22 extends from the second end surface 12 to the first side surface 13.

[0120] In the laminated inductor 1 , the first side surface 13 of the base body 10 serves as a mounting surface.

[0121] like Figure 10 As shown in FIG. 1 , in the laminated inductor 5 , the coil axis direction C is parallel to the lamination direction of the green body 10 . Figure 10 In the illustrated example, the coil axis direction C is a direction parallel to the third direction D3 and a direction perpendicular to the first direction D1 and the second direction D2.

[0122] Figure 10 The illustrated laminated inductor 5 has a so-called horizontally wound structure. Specifically, in the laminated inductor 5, the coil axis direction C is parallel to the first side surface 13, which serves as the mounting surface of the base body 10. The first and second external electrodes 21 and 22 extend to the first side surface 13, which serves as the mounting surface of the horizontally wound laminated inductor 5.

[0123] In the laminated inductor 5 , the magnetic flux generated in the coil is not blocked by the external electrodes provided on the first side surface 13 or the mounting substrate, so the inductance and Q value are improved.

[0124] [Method for Manufacturing Laminated Inductor]

[0125] Figure 1 as well as Figure 2 The laminated inductor 1 shown in FIG. 1 is manufactured, for example, by the following method.

[0126] <Process of Producing a Mother Laminated Body>

[0127] As an example, refer to Figure 11 A description will be given of a process for producing a mother laminate by forming the respective insulating layers from the insulating layer 17 i toward the insulating layer 17 a .

[0128] Figure 11 yes Figure 1 Another example of an exploded perspective view of a stacked inductor is shown.

[0129] exist Figure 2 In FIG. 1 , the lead conductors and the internal conductors are provided on the second main surface 16 side of the surface of each insulating layer. Figure 11 In the Figure 2The same structure is shown in the figure, in which each lead conductor and each internal conductor are provided on the surface of each insulating layer on the first main surface 15 side. Figure 11 The steps of manufacturing the laminated inductor 1 shown in FIG. 1 are described below.

[0130] First, an insulating paste layer is formed by repeatedly applying an insulating paste containing a glass material mainly composed of borosilicate glass, for example, by screen printing, etc. The insulating paste layer formed here will later become the insulating layer 17i.

[0131] Next, a photosensitive conductive paste layer is formed on the insulating paste layer, for example, by applying a photosensitive conductive paste primarily composed of a metal such as Ag using screen printing. The photosensitive conductive paste layer is then irradiated with ultraviolet light or other light through a photomask and then developed with an alkaline solution or other light source, thereby forming an external conductor layer and a second lead conductor layer on the insulating paste layer. As described above, the external conductor layer and the second lead conductor layer are formed using photolithography. The external conductor layer formed here will later become a portion of the first external electrode 21 and the second external electrode 22, respectively. The same applies to the external conductor layers formed below. The second lead conductor layer formed here will later become the second lead conductor 42.

[0132] Furthermore, when forming the outer conductor layer and the second lead conductor layer, instead of exposure using a photomask, for example, DI exposure (also referred to as direct image exposure or direct drawing) without using a photomask may be performed.

[0133] Next, a new insulating paste layer is formed on the already formed insulating paste layer by applying a photosensitive insulating paste made of a glass material primarily composed of borosilicate glass, for example, using screen printing or other methods. The newly formed insulating paste layer is then irradiated with ultraviolet light or other materials through a photomask and then developed with an alkaline solution or other methods, thereby forming via holes and openings in the insulating paste layer. As described above, an insulating paste layer having multiple via holes and openings is formed using photolithography. This insulating paste layer will later become insulating layer 17h. The via holes formed here overlap with a portion of the already formed second lead conductor layer. The openings formed here overlap with the already formed external conductor layer.

[0134] Furthermore, when forming an insulating paste layer provided with via holes and openings, for example, DI exposure without using a photomask may be performed instead of exposure using a photomask.

[0135] Next, for example, by applying a photosensitive conductive paste primarily composed of a metal such as Ag using screen printing, a new photosensitive conductive paste layer is formed inside the vias and openings, while a new photosensitive conductive paste layer is simultaneously formed on the already formed insulating paste layer. Furthermore, after irradiating the photosensitive conductive paste layer with ultraviolet light through a photomask, it is developed using an alkaline solution, thereby forming a connecting conductor layer inside the vias, a coil conductor layer connected to the connecting conductor layer is simultaneously formed on the insulating paste layer, and a new external conductor layer connected to the already formed external conductor layer is formed inside the openings, while a new external conductor layer is simultaneously formed on the external conductor layer. As described above, the coil conductor layer, connecting conductor layer, and external conductor layer are formed using photolithography. The coil conductor layer formed here will later become coil conductor 31. The connecting conductor layer formed here will later become second via conductor 62.

[0136] In addition, when forming the coil conductor layer, the connection conductor layer, and the external conductor layer, instead of exposure using a photomask, for example, DI exposure without using a photomask may be performed.

[0137] By repeating the above steps, the insulating paste layer, coil conductor layer, connecting conductor layer, and external conductor layer are formed into a predetermined laminated structure. The insulating paste layers formed here become insulating layers 17g, 17f, 17e, and 17d. The coil conductor layer formed here will later become coil conductor 31. The connecting conductor layer formed here will become connecting conductor 32.

[0138] Next, a new insulating paste layer is formed on the already formed insulating paste layer, for example, by applying a photosensitive insulating paste made of a glass material primarily composed of borosilicate glass, using screen printing or other methods. The newly formed insulating paste layer is then irradiated with ultraviolet light or other light through a photomask and then developed with an alkaline solution or other method to form via holes and openings in the insulating paste layer. As described above, photolithography is used to form an insulating paste layer having multiple via holes and openings. This insulating paste layer will later become insulating layer 17c. The via holes formed here overlap with a portion of the already formed coil conductor layer. The openings formed here overlap with the already formed external conductor layer.

[0139] Furthermore, when forming an insulating paste layer provided with via holes and openings, for example, DI exposure without using a photomask may be performed instead of exposure using a photomask.

[0140] Next, a photosensitive conductive paste primarily composed of a metal such as Ag is applied, for example, by screen printing. A new photosensitive conductive paste layer is formed inside the via holes and openings, and a new photosensitive conductive paste layer is simultaneously formed on the already formed insulating paste layer. Furthermore, after irradiating the photosensitive conductive paste layer with ultraviolet light or the like through a photomask and then developing it with an alkaline solution or the like, a connecting conductor layer is formed inside the via holes, and a first lead conductor layer connected to the connecting conductor layer is simultaneously formed on the insulating paste layer. Furthermore, a new external conductor layer connected to the already formed external conductor layer is formed inside the openings, and a new external conductor layer is simultaneously formed on the existing external conductor layer. In this manner, the connecting conductor layer, the external conductor layer, and the first lead conductor layer are formed using photolithography. The connecting conductor layer formed here will later become the first via hole conductor 61. The first lead conductor layer formed here will later become the first lead conductor 41.

[0141] Furthermore, when forming the connection conductor layer, the external conductor layer, and the first lead conductor layer, instead of exposure using a photomask, for example, DI exposure without using a photomask may be performed.

[0142] Next, a new insulating paste layer is formed on the already formed insulating paste layer by applying a photosensitive insulating paste made of a glass material primarily composed of borosilicate glass, for example, using screen printing or other methods. The newly formed insulating paste layer is then irradiated with ultraviolet light or other materials through a photomask and then developed with an alkaline solution or other materials to form openings in the insulating paste layer. As described above, an insulating paste layer having multiple openings is formed using photolithography. This insulating paste layer will later become insulating layer 17b. The openings formed here overlap with the already formed outer conductive layer.

[0143] In addition, when forming the insulating paste layer provided with the opening, instead of the exposure using a photomask, for example, DI exposure without using a photomask may be performed.

[0144] Next, a new photosensitive conductive paste layer, primarily composed of a metal such as Ag, is applied, for example, by screen printing. This layer is then irradiated with ultraviolet light or the like through a photomask and then developed with an alkaline solution or the like. This forms a new external conductive layer within the opening, connecting to the already formed external conductive layer. Simultaneously, a new external conductive layer is formed on top of the existing external conductive layer. The external conductive layer is formed by photolithography in the aforementioned manner.

[0145] In addition, when forming the outer conductive layer, instead of exposure using a photomask, for example, DI exposure without using a photomask may be performed.

[0146] Next, a new insulating paste layer is formed on the already formed insulating paste layer by applying a photosensitive insulating paste, for example, using screen printing. The newly formed insulating paste layer is then irradiated with ultraviolet light or the like through a photomask and then developed using an alkaline solution or the like, thereby forming openings in the insulating paste layer. As described above, an insulating paste layer having openings in multiple locations is formed using photolithography. The insulating paste layer formed here will later become insulating layer 17a. The openings formed here overlap with the already formed external conductor layer. Furthermore, openings for providing external conductors, which will later become portions of the first external electrode 21 and the second external electrode 22 exposed on the first main surface 15 of the green body 10, are formed on the surface of the green body 10 that will later become the first main surface 15.

[0147] In addition, when forming the insulating paste layer provided with the opening, instead of the exposure using a photomask, for example, DI exposure without using a photomask may be performed.

[0148] Next, a new photosensitive conductive paste layer is formed inside the opening by applying a photosensitive conductive paste containing Ag or other metal as a main component, for example, by screen printing. Furthermore, after the photosensitive conductive paste layer is irradiated with ultraviolet light or the like through a photomask, it is developed with an alkaline solution or the like, thereby forming a new external conductive layer connected to the already formed external conductive layer inside the opening, and simultaneously forming a new external conductive layer on the existing external conductive layer. External conductive layers that will later become portions of the first external electrode 21 and the second external electrode 22 exposed on the first main surface 15 of the body 10 are formed on the surface that will later become the first main surface 15 of the body 10. The external conductive layer formed here can be formed integrally with the first main surface 15 of the body 10, or it can be formed so as to protrude from the first main surface 15 of the body 10. As described above, the external conductive layer is formed by photolithography.

[0149] In addition, when forming the outer conductive layer, instead of exposure using a photomask, for example, DI exposure without using a photomask may be performed.

[0150] The development resolution limit of the above-mentioned photosensitive insulating paste is, for example, 3 μm or less when irradiated with ultraviolet light having a light source wavelength of 365 / 405 nm.

[0151] Through the above, a mother laminated body is produced.

[0152] The method for forming the conductor patterns of the coil conductor layer, the connecting conductor layer, the external conductor layer, the first lead conductor layer and the second lead conductor layer is not limited to the above-mentioned photolithography method. For example, it can also be a method of printing and stacking a conductive paste using a screen printing plate whose openings are set to the shape of the conductor pattern, or a method of forming a conductor film by sputtering, evaporation, foil pressing, etc., and then etching the conductor film into the shape of the conductor pattern. It can also be a method of forming a negative pattern by a semi-additive method and then forming a plated film, and then removing unnecessary parts of the plated film by etching to form the shape of the conductor pattern.

[0153] When forming the conductor patterns for the coil conductor layer, connection conductor layer, external conductor layer, first lead conductor layer, and second lead conductor layer, a high aspect ratio is achieved by forming the conductor patterns in multiple stages, thereby reducing losses due to resistance at high frequencies. The method for forming the conductor patterns in stages is not particularly limited. For example, a method of repeatedly stacking conductor patterns by repeating a photolithography process as described above, a method of repeatedly stacking conductor patterns formed using a semi-additive process, a method of stacking conductor patterns formed using a semi-additive process and another conductor pattern formed by etching a plated film grown by electroplating in a different order, or a method of further growing a plated film formed using a semi-additive process by electroplating can also be used.

[0154] The conductive material of the conductor patterns constituting the coil conductor layer, the connecting conductor layer, the external conductor layer, the first lead conductor layer and the second lead conductor layer is not limited to the above-mentioned photosensitive conductive paste with Ag and other metals as the main components. For example, it can also be a conductor containing metals such as Ag, Au, Cu, etc. formed by sputtering, evaporation, foil pressing, electroplating, etc.

[0155] The method of forming the insulating paste layer is not limited to the above-mentioned photolithography method, and may be, for example, a method of pressing a sheet made of an insulating material, a method of spin coating the insulating material, or a method of spray coating the insulating material.

[0156] The method of forming an insulating paste layer having conductive holes and openings is not limited to the above-mentioned photolithography method. For example, it can also be a method of forming an insulating film by crimping a sheet made of insulating material, spin coating insulating material, spraying insulating material, etc., and then performing laser processing, drilling processing, etc. on the insulating film to provide conductive holes and openings.

[0157] The insulating material constituting the insulating paste layer is not limited to the aforementioned glass material primarily composed of borosilicate glass. For example, it may also be a ceramic material, an organic material such as epoxy resin, fluororesin, or polymer resin, or a composite material such as glass epoxy resin. As the insulating material, a material having a low dielectric constant and dielectric loss is particularly preferred.

[0158] <Process of forming the base body, coil, and external electrodes>

[0159] First, the mother laminate is cut by dicing or the like to be individualized into a plurality of unfired laminates.

[0160] The unfired laminate has an insulating paste laminate portion formed by laminating insulating paste layers, a coil conductor laminate portion formed by laminating coil conductor layers so that adjacent coil conductor layers are electrically connected via connecting conductor layers, an external conductor laminate portion formed by laminating external conductor layers, a first lead conductor portion where a first lead conductor layer is located, and a second lead conductor portion where a second lead conductor layer is located.

[0161] When the unfired laminate is singulated, the outer conductor laminate is exposed at two locations on at least the bottom surface of the insulating paste laminate included in the cut surface of the unfired laminate.

[0162] Next, the unfired laminate is fired to produce a laminate.

[0163] When the unfired laminate is fired, the insulating paste layer becomes the insulating layer, and the insulating paste laminate portion becomes the green body 10. Furthermore, when the unfired laminate is fired, the coil conductor layer becomes the coil wiring, and the coil conductor laminate portion becomes the internal conductor 30. Furthermore, when the unfired laminate is fired, one of the two external conductor laminate portions becomes part of the first external electrode 21, and the other becomes part of the second external electrode 22. Furthermore, when the unfired laminate is fired, the first lead conductor portion becomes the first lead conductor 41, and the second lead conductor portion becomes the second lead conductor 42.

[0164] Next, the obtained laminate may be subjected to, for example, barrel grinding to round the corners and ridges of the green body 10 .

[0165] Finally, the two fired outer conductor laminated portions may be used as base electrodes, and a Ni-plated electrode and a Sn-plated electrode may be formed sequentially on the surface of each base electrode by electroplating. The thickness of each Ni-plated electrode and Sn-plated electrode may be, for example, 2 μm or more and 10 μm or less.

[0166] In this way, the first external electrode 21 and the second external electrode 22 are formed, which have a base electrode, a Ni-plated electrode, and a Sn-plated electrode in this order from the surface side of the green body 10. In this case, the base electrode and the surface side of the green body 10 ( Figure 1 In the embodiment, the first end face 11 and the first main face 15 of the blank 10 are integrated, and the Ni-plated electrode and the Sn-plated electrode are formed from the surface of the blank 10 (at Figure 1In the embodiment, the first end face 11 and the first main face 15 of the green body 10 are raised to cover the base electrode. In addition, the base electrode and the surface of the green body 10 (at the Figure 1 In the embodiment, the second end face 12 and the first main face 15 of the blank 10 are integrated, and the Ni-plated electrode and the Sn-plated electrode are formed from the surface of the blank 10 (at Figure 1 In the embodiment, the second end surface 12 and the first main surface 15 of the green body 10 are raised to cover the base electrode.

[0167] The first external electrode 21 and the second external electrode 22 may not include the Ni-plated electrode and the Sn-plated electrode, but may only include the base electrode. Alternatively, the first external electrode 21 and the second external electrode 22 may include another plating electrode such as Au instead of the Ni-plated electrode and the Sn-plated electrode.

[0168] The method for forming the external electrode is not limited to the method of plating the external conductor laminate portion exposed on the cut surface of the unfired laminate (at least the bottom surface of the insulating paste laminate portion) as described above. For example, it can also be a method of exposing the external conductor laminate portion to the cut surface of the unfired laminate (at least the bottom surface of the insulating paste laminate portion) as described above, and then dipping (dip) the exposed portion of the external conductor laminate portion into the conductive paste, or forming a film of the conductive paste on the exposed portion of the external conductor laminate portion by sputtering and then performing electroplating.

[0169] Through the above-described process, the laminated inductor 1 is manufactured.

[0170] The multilayer inductor 1 is manufactured in a size of, for example, 0402 (0.4 mm×0.2 mm×0.2 mm). The size of the multilayer inductor 1 is not limited to the size of 0402 (0.4 mm×0.2 mm×0.2 mm).

[0171] The following contents are disclosed in this specification.

[0172] <1>

[0173] A stacked inductor comprising:

[0174] The blank has a first end surface and a second end surface facing each other in a first direction;

[0175] a first external electrode, disposed on the first end surface;

[0176] a second external electrode, disposed on the second end surface;

[0177] an inner conductor disposed inside the green body and wound along a coil axis direction perpendicular to the first direction;

[0178] a first lead conductor disposed inside the green body and connecting the internal conductor to the first external electrode; and

[0179] The second lead conductor is provided inside the body and connects the internal conductor to the second external electrode.

[0180] When viewed from the direction of the coil axis, the straight line obtained by extending the first boundary portion along the first direction does not overlap with the second boundary portion, and the second lead conductor has a curved shape that bulges away from the straight line obtained by extending the first boundary portion along the first direction, wherein the first boundary portion is the boundary between the first lead conductor and the internal conductor, and the second boundary portion is the boundary between the second lead conductor and the internal conductor.

[0181] <2>

[0182] The multilayer inductor according to <1> is characterized in that:

[0183] The green body has a first side surface and a second side surface facing each other in a second direction, wherein the second direction is orthogonal to the first direction and the coil axis direction.

[0184] When viewed from the coil axis direction, the first boundary portion exists on the first side surface relative to the center of the green body, and the second boundary portion exists on the second side surface relative to the center of the green body.

[0185] <3>

[0186] The multilayer inductor according to <1> or <2> is characterized in that:

[0187] The first lead conductor has a straight shape when viewed from the coil axis direction.

[0188] <4>

[0189] The multilayer inductor according to any one of <1> to <3>, characterized in that:

[0190] The second lead conductor extends in a tangential direction along the second boundary portion of the circling path of the inner conductor at the second boundary portion when viewed from the coil axis direction.

[0191] <5>

[0192] The multilayer inductor according to any one of <1> to <4>, characterized in that:

[0193] When viewed from the coil axis direction, the second lead conductor is connected to the second external electrode at a portion connected to the second external electrode.

[0194] <6>

[0195] The multilayer inductor according to any one of <1> to <5>, characterized in that:

[0196] The first lead conductor, the inner conductor, and the second lead conductor are stacked in this order from one side to the other side in the coil axis direction.

[0197] The inner conductor and the first lead conductor are connected via a first via-hole conductor.

[0198] The inner conductor and the second lead conductor are connected via a second via-hole conductor.

[0199] <7>

[0200] The multilayer inductor according to any one of <1> to <6>, characterized in that:

[0201] The green body has a first main surface and a second main surface facing each other in the coil axis direction.

[0202] The first external electrode extends from the first end surface to the first main surface,

[0203] The second external electrode extends from the second end surface to the first main surface.

[0204] <8>

[0205] The laminated inductor according to <7> is characterized in that:

[0206] When viewed from the coil axis, the first lead conductor has a straight line shape.

[0207] Among the first lead conductor, the second lead conductor, and the internal conductor, the first lead conductor is located closest to the first main surface.

[0208] <9>

[0209] The multilayer inductor according to any one of <1> to <6>, characterized in that:

[0210] The green body has a first side surface and a second side surface facing each other in a second direction, wherein the second direction is orthogonal to the first direction and the coil axis direction.

[0211] The first external electrode extends from the first end surface to the first side surface.

[0212] The second external electrode extends from the second end surface to the first side surface.

Claims

1. A stacked inductor, characterized in that: have: The blank has a first end surface and a second end surface facing each other in a first direction; a first external electrode, disposed on the first end surface; a second external electrode, disposed on the second end surface; an inner conductor disposed inside the green body and wound along a coil axis direction perpendicular to the first direction; a first lead conductor disposed inside the green body and connecting the internal conductor to the first external electrode; and The second lead conductor is provided inside the body and connects the internal conductor to the second external electrode. When viewed from the direction of the coil axis, the straight line obtained by extending the first boundary portion along the first direction does not overlap with the second boundary portion, and the second lead conductor has a curved shape that bulges away from the straight line obtained by extending the first boundary portion along the first direction, wherein the first boundary portion is the boundary between the first lead conductor and the internal conductor, and the second boundary portion is the boundary between the second lead conductor and the internal conductor.

2. The laminated inductor according to claim 1, wherein: The green body has a first side surface and a second side surface facing each other in a second direction, wherein the second direction is orthogonal to the first direction and the coil axis direction. When viewed from the coil axis direction, the first boundary portion exists on the first side surface relative to the center of the green body, and the second boundary portion exists on the second side surface relative to the center of the green body.

3. The laminated inductor according to claim 1 or 2, wherein: The first lead conductor has a straight shape when viewed from the coil axis direction.

4. The laminated inductor according to any one of claims 1 to 3, wherein: The second lead conductor extends in a tangential direction along the second boundary portion of the circling path of the inner conductor at the second boundary portion when viewed from the coil axis direction.

5. The laminated inductor according to any one of claims 1 to 4, wherein: When viewed from the coil axis direction, the second lead conductor is connected to the second external electrode at a portion connected to the second external electrode.

6. The laminated inductor according to any one of claims 1 to 5, wherein: The first lead conductor, the inner conductor, and the second lead conductor are stacked in this order from one side to the other side in the coil axis direction. The inner conductor and the first lead conductor are connected via a first via-hole conductor. The inner conductor and the second lead conductor are connected via a second via-hole conductor.

7. The laminated inductor according to any one of claims 1 to 6, wherein: The green body has a first main surface and a second main surface facing each other in the coil axis direction. The first external electrode extends from the first end surface to the first main surface, The second external electrode extends from the second end surface to the first main surface.

8. The laminated inductor according to claim 7, wherein: When viewed from the coil axis, the first lead conductor has a straight line shape. Among the first lead conductor, the second lead conductor, and the internal conductor, the first lead conductor is located closest to the first main surface.

9. The laminated inductor according to any one of claims 1 to 6, wherein: The green body has a first side surface and a second side surface facing each other in a second direction, wherein the second direction is orthogonal to the first direction and the coil axis direction. The first external electrode extends from the first end surface to the first side surface. The second external electrode extends from the second end surface to the first side surface.

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