Inductor

Abstract

To provide an inductor having a chip shape and good magnetic efficiency.SOLUTION: The coil 20 is configured by connecting in series a plurality of unit coils 21 helically wound along coil axes CA, the plurality of unit coils 21 are disposed adjacent to each other in the same direction such that the coil axes CA are parallel to each other, and the adjacent unit coils 21 are connected in series by connecting first end portions 21a located in a positive direction of the coil axes CA or second end portions 21b located in a negative direction of the coil axes CA. When viewed from the coil axis CA, all the unit coils 21 are wound in the same direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an inductor. [Background technology]

[0002] Toroidal inductors are known as a shape that makes it easy to obtain high inductance. In recent years, there has been a demand for the development of chip-shaped inductors that have the same high magnetic efficiency as toroidal inductors.

[0003] Patent Document 1 discloses an inductor comprising a magnetic core formed by pressure molding a mixture of powdered magnetic material and a binder, a coil element embedded in the magnetic core and having ends exposed from the end faces of the magnetic core, and external electrodes electrically and mechanically connected to the ends of the coil element, the coil element being wound to have a toroidal coil shape. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2023 / 157407 Summary of the Invention [Problem to be solved by the invention]

[0005] As in Patent Document 1, when a coil element with a shape similar to that of a toroidal inductor is incorporated into a chip-shaped magnetic core (also called an element body), it functions as an inductor, but the center and corners of the magnetic core (element body) cannot be used as paths for magnetic flux or current, resulting in a large amount of dead space.

[0006] The present invention has been made to solve the above problems, and has as its object to provide a chip-shaped inductor with good magnetic efficiency. [Means for solving the problem]

[0007] The inductor of the present invention comprises a base body and a coil provided inside the base body, the coil being constructed by connecting in series a plurality of unit coils wound spirally along a coil axis, the unit coils being arranged adjacent to each other in the same direction so that the coil axes of each unit coil are parallel, adjacent unit coils being connected in series by connecting first ends located in the positive direction of the coil axis or second ends located in the negative direction of the coil axis, and the winding direction of all unit coils being the same when viewed from the coil axis. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a chip-shaped inductor with good magnetic efficiency. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic perspective view showing an example of an inductor according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a side view of the inductor shown in FIG. 1, seen from a direction parallel to the coil axis. [Figure 3] FIG. 3 is a plan view of the inductor shown in FIG. 1, seen from a direction parallel to the coil axis and perpendicular to the direction in which the unit coils are adjacent to each other. [Figure 4] FIG. 4 is a schematic perspective view showing a modified example of the inductor according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a side view of the inductor shown in FIG. 4, seen from a direction parallel to the coil axis. [Figure 6] FIG. 6 is a plan view of the inductor shown in FIG. 4, seen from a direction parallel to the coil axis and perpendicular to the direction in which the unit coils are adjacent to each other. [Figure 7] FIG. 7 is a schematic perspective view showing an example of an inductor according to the second embodiment of the present invention. [Figure 8] FIG. 8 is a side view of the inductor shown in FIG. 7, seen from a direction parallel to the coil axis. [Figure 9]FIG. 9 is a plan view of the inductor shown in FIG. 7, seen from a direction parallel to the coil axis and perpendicular to the direction in which the unit coils are adjacent to each other. [Figure 10] FIG. 10 is an exploded perspective view showing a schematic example of a laminate constituting the inductor when the inductor shown in FIG. 1 is a laminate type. [Figure 11] FIG. 11 is a perspective view that schematically shows the magnetic flux that is generated when a current flows through the inductor shown in FIG. [Figure 12] FIG. 12 is a perspective view that schematically shows the magnetic flux that is generated when a current flows through the inductor shown in FIG. [Figure 13] FIG. 13 is a perspective view that schematically shows magnetic flux that is generated when a current flows through the inductor shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] The inductor of the present invention will be described below. Note that the present invention is not limited to the following configuration and may be modified as appropriate without departing from the spirit of the present invention. Furthermore, a combination of multiple individual preferred configurations described below also constitutes the present invention.

[0011] The following embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. From the second embodiment onwards, descriptions of matters common to the first embodiment will be omitted, and differences will be mainly described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment.

[0012] In the following description, when no particular distinction is made between the embodiments, they will simply be referred to as "the inductor of the present invention."

[0013] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, scale, etc. may differ from those of the actual product.

[0014] In this specification, terms indicating the relationship between elements (e.g., "perpendicular," "parallel," "orthogonal," etc.) and terms indicating the shapes of elements are not expressions that only express a strict meaning, but are expressions that mean that a range of substantial equivalence, for example, a difference of about a few percent, is included. Furthermore, in this specification, "equivalent" or "constant" is not an expression that means only completely equivalent or constant, but is an expression that means that a range of substantial equivalence or constant, for example, a difference of about a few percent, is included.

[0015] An inductor according to a first embodiment of the present invention will be described with reference to FIGS. 1, 2 and 3. FIG.

[0016] Fig. 1 is a schematic perspective view showing an example of an inductor according to a first embodiment of the present invention. Fig. 2 is a side view of the inductor shown in Fig. 1, seen from a direction parallel to the coil axis. Fig. 3 is a plan view of the inductor shown in Fig. 1, seen from a direction parallel to the coil axis and perpendicular to the direction in which unit coils are adjacent to each other.

[0017] The inductor 100 shown in FIGS. 1, 2 and 3 includes an element body 10 and a coil 20 provided inside the element body 10.

[0018] The coil 20 includes three unit coils 21A, 21B, and 21C. Hereinafter, the unit coils 21A, 21B, and 21C may be collectively referred to as unit coils 21.

[0019] Each unit coil 21 has a first end 21a and a second end 21b. The first end 21a refers to the first ends 21Aa, 21Ba, and 21Ca of unit coils 21A, 21B, and 21C. The second end 21b refers to the second ends 21Ab, 21Bb, and 21Cb of unit coils 21A, 21B, and 21C. The unit coil 21 is wound spirally from the first end 21a to the second end 21b along the coil axis CA.

[0020] As shown in FIG. 2, the shape (winding shape) of the unit coil 21 when viewed in a direction parallel to the coil axis CA (Y direction in FIG. 1, etc.) is rectangular. The winding shape is not particularly limited and may be square, triangular, circular, elliptical, etc. The winding shape of the unit coil 21 of this embodiment has the same shape and size from the first end 21a to the second end 21b. The winding shape of the unit coil 21 may be a shape that gradually increases or decreases from the first end 21a to the second end 21b. Examples of such shapes of the unit coil 21 include a quadrangular pyramid truncated shape, a triangular pyramid truncated shape, and a circular cone truncated shape.

[0021] The unit coils 21A, 21B, and 21C may all have the same winding shape and size, or some or all of them may be different.

[0022] When viewed from the coil axis CA, all of the unit coils 21A, 21B, and 21C have the same winding direction. In the example shown in Fig. 1, the unit coils 21A, 21B, and 21C are right-handed. The unit coils 21A, 21B, and 21C may also be left-handed.

[0023] As shown in Figures 1, 2 and 3, the unit coils 21A, 21B and 21C are arranged adjacent to each other in the same direction (X direction in Figure 1, etc.) in the order of unit coils 21A, 21B and 21C so that their respective coil axes CA are parallel.

[0024] The unit coils 21A, 21B, and 21C are arranged such that the first ends 21Aa, 21Ba, and 21Ca are located in the positive direction P of the coil axis CA, and the second ends 21Ab, 21Bb, and 21Cb are located in the negative direction N of the coil axis CA.

[0025] Adjacent unit coils 21 are connected in series by connecting their first ends 21a located in the positive direction P of the coil axis CA or their second ends 21b located in the negative direction N of the coil axis CA. In FIGS. 1, 2 and 3, the first end 21Aa of the unit coil 21A and the first end 21Ba of the unit coil 21B are connected via a connection portion 22. Furthermore, the second end 21Bb of the unit coil 21B and the second end 21Cb of the unit coil 21C are connected via a connection portion 22. In this way, the unit coils 21A, 21B and 21C are connected in series.

[0026] When viewed from the coil axis CA, it is preferable that the area enclosed by the inner periphery 21Bc of the unit coil 21B located in the center is equal to the area enclosed by the inner periphery 21Ac of the unit coil 21A located at one end, and is also equal to the area enclosed by the inner periphery 21Cc of the unit coil 21C located at the other end. As shown in Fig. 2, when viewed from the coil axis CA, the area enclosed by the inner peripheries 21Ac, 21Bc, and 21Cc of the unit coils 21A, 21B, and 21C, respectively, is equal.

[0027] The element body 10 is, for example, a rectangular parallelepiped having a first side surface 11 and a second side surface 12 that face each other in a direction parallel to the coil axis CA, and a third side surface 13 and a fourth side surface 14 that face each other in the direction in which the unit coils 21A, 21B, and 21C are adjacent to each other. In this case, the element body 10 further has a top surface 15 and a bottom surface 16, and the first side surface 11, the second side surface 12, the third side surface 13, and the fourth side surface 14 connect the outer edges of the top surface 15 and the bottom surface 16. The element body 10 may have rounded corners and ridges. A corner is a portion where three sides of the element body 10 intersect, and a ridge is a portion where two sides of the element body 10 intersect.

[0028] The distance from the first end 21a to the second end 21b of each unit coil 21 in the direction parallel to the coil axis CA is preferably 85% to 95% of the distance from the first side face 11 to the second side face 12 of the element body 10. In the example shown in Fig. 3, the distance L1 from the first end 21a to the second end 21b of each unit coil 21 in the direction parallel to the coil axis CA is approximately 90% of the distance L2 from the first side face 11 to the second side face 12 of the element body 10. The distance from the first end 21a to the second end 21b of each unit coil 21 may be 50% or more of the distance from the first side face 11 to the second side face 12 of the element body 10.

[0029] In the direction in which the unit coils 21 are adjacent to each other, the distance from the outer periphery on the third side face 13 side of the unit coil 21 arranged closest to the third side face 13 to the outer periphery on the fourth side face 14 side of the unit coil 21 arranged closest to the fourth side face 14 is preferably 85% or more and 95% or less of the distance from the third side face 13 to the fourth side face 14 of the element body 10. In the example shown in FIG. 2 , the distance W1 from the third side face 13 side of the unit coil 21A to the fourth side face 14 side of the unit coil 21C is approximately 90% of the distance W2 from the third side face 13 to the fourth side face 14 of the element body 10. The distance from the outer periphery on the third side face 13 side of the unit coil 21 arranged closest to the third side face 13 to the outer periphery on the fourth side face 14 side of the unit coil 21 arranged closest to the fourth side face 14 may be 50% or more of the distance from the third side face 13 to the fourth side face 14 of the element body 10.

[0030] As shown in FIGS. 1 and 3, the coil 20 has a first lead conductor 23A that extends perpendicularly to the first side surface 11 of the element body 10 from the first end 21Ca of the unit coil 21C.

[0031] The coil 20 has a second lead conductor 23B that extends perpendicularly to the second side surface 12 of the element body 10 from the second end 21Ab of the unit coil 21A.

[0032] The inductor of this embodiment is configured by connecting three unit coils in series. The number of unit coils is preferably an odd number. The number of unit coils may be five or more, but three is more preferable.

[0033] 1 and 3, the inductor 100 has unit coils 21A, 21B, and 21C all having the same number of turns (11 turns each in FIGS. 1 and 3). The number of turns may be the same for all unit coils, or may be different for some or all unit coils.

[0034] A first external electrode and a second external electrode (not shown) may be provided on the outer surface of the element body 10, and connected to the first lead conductor 23A and the second lead conductor 23B, respectively.

[0035] Although the element body 10 of this embodiment has a rectangular parallelepiped shape, the shape of the element body 10 is not particularly limited, and may be a cube, a polygonal pillar shape other than a rectangular parallelepiped, a cylindrical shape, or the like.

[0036] The constituent material of the element body 10 is preferably a magnetic material such as a ferrite material or a metal magnetic material. Alternatively, it may be a resin mixed with a ferrite material or a metal magnetic material, a non-magnetic material such as alumina or silica, or a resin mixed with a non-magnetic material. A mixed material of a magnetic material and a non-magnetic material may also be used.

[0037] The material of which the coil 20 is made is not particularly limited, but examples thereof include metals such as Ag, Au, Cu, Pd, Ni, and Al, and alloys containing at least one of these metals.

[0038] Next, an inductor 101, which is a modification of the inductor 100 according to the first embodiment, will be described with reference to FIGS.

[0039] Fig. 4 is a schematic perspective view showing a modified example of the inductor according to the first embodiment of the present invention. Fig. 5 is a side view of the inductor shown in Fig. 4, seen from a direction parallel to the coil axis. Fig. 6 is a plan view of the inductor shown in Fig. 4, seen from a direction parallel to the coil axis and perpendicular to the direction in which the unit coils are adjacent to each other.

[0040] 4, 5, and 6, the inductor 101 has a larger winding shape for the unit coil 21B disposed at the center than the unit coils 21A and 21C disposed at both ends. When viewed from the coil axis CA, it is preferable that the area surrounded by the inner periphery 21Bc of the unit coil 21B disposed at the center is equal to the sum of the areas surrounded by the inner peripheries 21Ac and 21Cc of the unit coils 21A and 21C disposed at both ends. When viewed from the coil axis CA, as shown in FIG. 5, the area surrounded by the inner periphery 21Bc of the unit coil 21B disposed at the center is equal to the sum of the areas surrounded by the inner periphery 21Ac of the unit coils 21A disposed at both ends and the inner periphery 21Cc of the unit coil 21C.

[0041] The unit coil 21A and the unit coil 21C have the same size and shape when viewed from the coil axis CA. The unit coil 21A and the unit coil 21C may have different sizes and / or different shapes, but preferably have the same size and shape.

[0042] 4 and 6, the number of turns of the unit coil 21B in the inductor 101 may be different from that in the inductor 100. In the inductor 100, the number of turns of the unit coils 21A, 21B, and 21C is 11, but in the inductor 101, the number of turns of the unit coils 21A and 21C is 11, and the number of turns of the unit coil 21B is 10. The number of turns of the unit coil 21B may be either more or less than the number of turns of the unit coils 21A and 21C.

[0043] In inductor 101, the number of turns of unit coil 21B is different from that of inductor 100, and therefore, as shown in FIG. 5, connection portion 22 connecting second end portion 21Bb of unit coil 21B and second end portion 21Cb of unit coil 21C is located on the bottom surface 16 side of element body 10.

[0044] Next, an inductor 200 according to a second embodiment of the present invention will be described with reference to FIGS.

[0045] Fig. 7 is a schematic perspective view showing an example of an inductor according to a second embodiment of the present invention. Fig. 8 is a side view of the inductor shown in Fig. 7, seen from a direction parallel to the coil axis. Fig. 9 is a plan view of the inductor shown in Fig. 7, seen from a direction parallel to the coil axis and perpendicular to the direction in which the unit coils are adjacent to each other.

[0046] 7, 8, and 9, the inductor 200 includes two unit coils. The second end 21Ab of the unit coil 21A and the second end 21Bb of the unit coil 21B are connected in series via a connection part 22. In the inductor 200, the connection part 22 extends from the top surface 15 side to the bottom surface 16 side of the element body 10, as shown in FIGS.

[0047] When viewed from the coil axis CA, it is preferable that the area enclosed by the inner periphery of one unit coil is equal to the area enclosed by the inner periphery of the other unit coil. As shown in Fig. 8, when viewed from the coil axis CA, the areas enclosed by the inner peripheries 21Ac and 21Bc of unit coils 21A and 21B are equal. The areas enclosed by the inner peripheries 21Ac and 21Bc of unit coils 21A and 21B may be different.

[0048] In the inductor 200, the first lead conductor 23A and the second lead conductor 23B are both located on the first side surface side.

[0049] In the inductor of this embodiment, the number of unit coils may be an even number. The number of unit coils may be four or more, but two is preferable.

[0050] The inductor of the present invention may be a molded type in which the coil is sealed with the constituent material of the element body, or a laminated type in which a coil conductor layer is formed on a portion of multiple insulating layers and the multiple stacked coil conductor layers are electrically connected, etc. The inductor of the present invention is suitable for the laminated type.

[0051] In the inductor of the present invention, it is preferable that the base body is constructed by stacking multiple insulating layers in a direction parallel to the coil axis, and each unit coil is constructed by electrically connecting multiple coil conductor layers stacked in a direction parallel to the coil axis together with the insulating layers.

[0052] The following describes the case where the inductor 100 according to the first embodiment is a multilayer type, with reference to FIG. FIG. 10 is an exploded perspective view showing a schematic example of a laminate constituting the inductor when the inductor shown in FIG. 1 is a laminate type.

[0053] As shown in FIG. 10, the inductor 100 is constructed by stacking a plurality of insulating layers 10a, 10b, 10c, 10d, 10e, 10f, 10g, and 10h from the second side surface 12 side of the base body 10 toward the first side surface 11 side in a direction parallel to the coil axis (hereinafter also referred to as the stacking direction).

[0054] In FIG. 10, insulating layer 10g is arranged on the lower side in the stacking direction (the second side surface 12 side of element body 10), and insulating layer 10h is arranged on the upper side in the stacking direction (the first side surface 11 side of element body 10).

[0055] The insulating layers 10a, 10b, 10c, 10d, 10e, and 10f are provided with coil conductor layers 24a, 24b, 24c, 24d, 24e, and 24f, and via conductors 25a, 25b, 25c, 25d, 25e, and 25f, respectively. The insulating layer 10g is provided with a via conductor 25g. The insulating layer 10h is provided with a via conductor 25h. The insulating layer 10g may be a single layer or two or more layers. Similarly, the insulating layer 10h may be a single layer or two or more layers. Hereinafter, the coil conductor layers 24a, 24b, 24c, 24d, 24e, and 24f will also be collectively referred to as coil conductor layer 24.

[0056] The coil conductor layers 24a, 24b, 24c, 24d, 24e, and 24f are provided on one main surface (the upper main surface in the stacking direction in FIG. 10) of the insulating layers 10a, 10b, 10c, 10d, 10e, and 10f, respectively, and are stacked together with the insulating layers 10a, 10b, 10c, 10d, 10e, 10f, 10g, and 10h. In FIG. 10, the coil conductor layers 24b, 24c, 24d, and 24e have a 3 / 4 turn shape, and four insulating layers arranged in this order, 10b, 10c, 10d, and 10e, form one unit (three turns), which are repeatedly stacked.

[0057] Via conductors 25a, 25b, 25c, 25d, 25e, 25f, 25g, and 25h are provided to penetrate insulating layers 10a, 10b, 10c, 10d, 10e, 10f, 10g, and 10h, respectively, in the stacking direction. Hereinafter, via conductors 25a, 25b, 25c, 25d, 25e, 25f, 25g, and 25h will also be collectively referred to as via conductors 25.

[0058] The constituent materials of each coil conductor layer 24 and each via conductor 25 include the metals and alloys mentioned above as constituent materials of the coil.

[0059] The insulating layers 10a, 10b, 10c, 10d, 10e, 10f, 10g, and 10h configured as described above are stacked in the stacking direction. The insulating layers 10a, 10b, 10c, 10d, 10e, 10f, 10g, and 10h form the element body 10, and the coil conductor layers 24a, 24b, 24c, 24d, 24e, and 24f are electrically connected via via conductors 25a, 25b, 25c, 25d, 25e, and 25f. As a result, a coil 20 having a coil axis parallel to the stacking direction is formed inside the element body 10.

[0060] Furthermore, the via conductor 25h becomes the first extension conductor 23A within the element body 10 and is exposed to the first side surface 11 of the element body 10. That is, the first extension conductor 23A includes the via conductor 25h.

[0061] The via conductor 25a and the via conductor 25g provided in the insulating layer 10a on which the coil conductor layer 24a closest to the second side surface 12 is provided become the second extension conductor 23B within the element body 10 and are exposed at the second side surface 12 of the element body 10. That is, the second extension conductor 23B includes the via conductors 25a and 25g.

[0062] An example of a method for manufacturing an inductor according to the present invention will be described below.

[0063] (Molding method) First, a conductor wire for making the coil is prepared. The conductor wire is preferably a metal wire (e.g., a rectangular copper wire) coated with a resin or the like. If the constituent material of the element body is a resin kneaded with a magnetic material or the like, this interacts with the resin coating the metal wire to firmly seal the conductor wire.

[0064] Next, the coil is produced by winding the conductor around the core. If the core is made of a molded product of the magnetic material that will be the constituent material of the element body, the coil can be sealed while being fixed to the core, preventing deformation of the coil.

[0065] Next, a molded body that will house the coil is prepared. The molded body is made of uncured or semi-cured resin kneaded with magnetic materials, etc. The coil housed in the molded body is then covered with the constituent material of the element body, placed in a mold, and then introduced into a pressure molding machine. The resin contained in the molded body is then cured for a period of 60 to 1800 seconds at a temperature of 150°C to 200°C and a pressure of 5 MPa to 50 MPa, for example, to form the inductor.

[0066] (Layer construction method) (Green sheet manufacturing process) For example, Ni-Cu-Zn ferrite powder is used as the ferrite, and predetermined amounts of Bi2O3, Mn2O3, and Cr2O3 are added. This mixture is placed in a ball mill together with PSZ media, and then an organic binder such as polyvinyl butyral resin, an organic solvent such as ethanol or toluene, a plasticizer, etc. are added and mixed to produce a slurry. The slurry is formed into a sheet of a predetermined thickness by a doctor blade method or the like, and then punched into a predetermined shape to produce a green sheet, whose thickness is, for example, 20 μm or more and 30 μm or less.

[0067] (Conductor pattern formation process) As a paste for the conductive pattern, for example, a predetermined amount of ethyl cellulose is added as a binder to Ag particles, and terpineol is added as a solvent to this, and the resulting paste is kneaded to prepare the paste. Next, via holes are formed by irradiating predetermined locations on the green sheet with a laser. The paste for the conductor pattern is applied to the surface of the green sheet by screen printing or the like, filling the via holes. As a result, conductor patterns for the via conductors are formed in the via holes of the green sheet, and conductor patterns for the coil conductor layer connected to the conductor patterns for the via conductor are formed on the surface. In this way, a coil sheet is produced in which conductor patterns for the coil conductor layer and conductor patterns for the via conductor are formed on the green sheet. The coil sheet is formed with a conductor pattern for the coil conductor layer corresponding to the coil conductor layer 24 shown in FIG. 10 and a conductor pattern for the via conductor corresponding to the via conductor 25 (excluding via conductors 25g and 25h). Separately from the coil sheet, a via sheet is produced in which conductor patterns for the via conductors corresponding to the via conductors 25g and 25h shown in FIG. 10 are formed.

[0068] (Laminated block manufacturing process) The coil sheets and via sheets are stacked in the stacking direction in the order corresponding to FIG. 10, and then pressed at a pressure of, for example, 450 MPa to prepare a laminate block.

[0069] (Laminate and coil manufacturing process) The laminate block is diced to produce individual chips. The individual chips are debindered in air at a predetermined temperature (400°C), and then heat-treated at 920°C. When the individual chips are heat-treated, the green sheets of the coil sheet and via sheet become insulating layers, and an element body is obtained. The insulating layer may be impregnated with epoxy resin to fill voids in the insulating layer. This completes the manufacture of the inductor of the present invention.

[0070] The obtained inductor may be subjected to barrel polishing to round the corners and edges of the element body. External electrodes may then be formed on the element body as needed. The external electrodes may be formed by plating, by applying a conductive paste to the element body and baking it, or by sputtering, among other methods.

[0071] The effects of the inductor of the present invention will be described below.

[0072] Fig. 11 is a perspective view that schematically shows the magnetic flux that is generated when a current flows through the inductor shown in Fig. 1. The current flows from IN to OUT in Fig. 11. 11, in the inductor 100, a plurality of unit coils are wound in the same direction, but the coil conductors are connected in a meandering direction, and the current flows in adjacent unit coils in opposite directions, resulting in opposite directions of magnetic flux generated between adjacent unit coils. In the inductor 100, the magnetic flux of the unit coil 21B located in the center is directed from the second side surface 12 to the first side surface 11, and the magnetic flux of the unit coils 21A and 21C located at both ends is directed from the first side surface 11 to the second side surface 12. The magnetic flux that comes out of the unit coil 21B located in the center near the first end portion 21Ba makes an arc that turns 180 degrees toward the two unit coils 21A and 21C located at both ends, and then splits into two. Near the second ends 21Ab and 21Cb, the magnetic fluxes that have come out of the unit coils 21A and 21C arranged at both ends make an arc that makes a 180-degree turn toward the unit coil 21B arranged in the center, and then converge into one.

[0073] Although the inductor of the present invention has a completely different coil shape from a toroidal coil, it forms a magnetic flux with a closed magnetic circuit structure similar to that of a toroidal coil. As a result, the inductor of the present invention functions in the same way as a toroidal coil, with little magnetic flux leakage.

[0074] In the inductor of the present invention, the multiple unit coils are wound in the same direction and arranged in the same direction, so there is almost no space in the center of the doughnut like in a toroidal coil, the dead space of the element body is narrowed, and high inductance can be achieved.

[0075] In the inductor of the present invention, all unit coils have the same winding direction and are arranged in the same direction, so the end points of the unit coils are close to each other, making it easy to connect adjacent coils and facilitating design within a chip shape (e.g., a rectangular parallelepiped).

[0076] Inductor 100 has a small stray capacitance and is designed for high frequencies because the current input (IN in FIG. 11) and output (OUT in FIG. 11) are separated. When there are an odd number of unit coils, it is easier to increase the distance between the first and second lead conductors compared to when there is an even number, and this makes it possible to reduce stray capacitance.

[0077] FIG. 12 is a perspective view that schematically shows the magnetic flux that is generated when a current flows through the inductor shown in FIG. Inductor 101 has the same number of unit coils (three) as inductor 100, but when viewed from the coil axis, the area surrounded by the inner periphery 21Bc of unit coil 21B located in the center is equal to the sum of the area surrounded by the inner periphery 21Ac of unit coils 21A located at both ends and the area surrounded by the inner periphery 21Cc of unit coil 21C. Inductor 100 and inductor 101 have two unit coils in the direction in which magnetic flux flows from first side surface 11 to second side surface 12 and one unit coil in the direction in which magnetic flux flows from second side surface 12 to first side surface 11, so in terms of magnetic flux density, the burden on unit coil 21B located in the center is heavy. In inductor 101, by designing the size of unit coil 21 as described above, the balance of magnetic flux can be improved as shown in FIG. 12. By improving the balance of magnetic flux, magnetic flux leakage can be further reduced compared to inductor 100. Reducing magnetic flux leakage can reduce both the influence on electronic components outside the inductor and the influence from external electronic components. In inductor 101, the magnetic flux is balanced by changing the area surrounded by the inner circumference of the unit coil, but a similar balance can also be achieved by making the areas surrounded by the inner circumference of the three unit coils the same and making the number of turns of unit coil 21B located in the center the sum of the number of turns of unit coils 21A and 21C located at both ends. By changing the balance of the magnetic flux, it is easy to design the coil so that the inductance is low.

[0078] FIG. 13 is a perspective view that schematically shows magnetic flux that is generated when a current flows through the inductor shown in FIG. While the inductors 100 and 101 have three unit coils, the inductor 200 has two unit coils connected in series, and has a configuration closer to that of a toroidal coil. Inductor 200 is easier to manufacture than inductors 100 and 101 because it has a smaller number of unit coils, and it is easier to manufacture a small-sized inductor. The inductor 200 has a large stray capacitance and is designed for lower frequencies because the current input (IN) and output (OUT) are close to each other.

[0079] The present specification discloses the following:

[0080] <1> The base body and a coil provided inside the element body, the coil is configured by connecting a plurality of unit coils in series, each unit coil being wound in a spiral shape along a coil axis; The plurality of unit coils are arranged adjacent to each other in the same direction so that the coil axes of each unit coil are parallel to each other, adjacent unit coils are connected in series by connecting first ends located in the positive direction of the coil axis or second ends located in the negative direction of the coil axis, An inductor in which the winding direction of all the unit coils is the same when viewed from the coil axis.

[0081] <2> The coil is configured by connecting an odd number of the unit coils in series. <1> The inductor according to claim 1.

[0082] <3> The coil is configured by connecting three of the unit coils in series. <2> The inductor according to claim 1.

[0083] <4> When viewed from the coil axis, the area enclosed by the inner periphery of the unit coil arranged at the center is equal to the sum of the areas enclosed by the inner peripheries of the unit coils arranged at both ends. <3> The inductor according to claim 1.

[0084] <5> When viewed from the coil axis, the area enclosed by the inner periphery of the unit coil arranged at the center is equal to the area enclosed by the inner periphery of the unit coil arranged at one end, and is also equal to the area enclosed by the inner periphery of the unit coil arranged at the other end. <3> The inductor according to claim 1.

[0085] <6> The coil is configured by connecting an even number of the unit coils in series. <1> The inductor according to claim 1.

[0086] <7> The coil is configured by connecting two of the unit coils in series. <6> The inductor according to claim 1.

[0087] <8> When viewed from the coil axis, an area enclosed by an inner periphery of one of the unit coils is equal to an area enclosed by an inner periphery of the other unit coil. <7> The inductor according to claim 1.

[0088] <9> the element body is configured by laminating a plurality of insulating layers in a direction parallel to the coil axis, Each of the unit coils is configured by electrically connecting a plurality of coil conductor layers stacked together with the insulating layer in a direction parallel to the coil axis. <1> ~ <8> 10. The inductor according to claim 9, wherein

[0089] <10> the element body is a rectangular parallelepiped having a first side surface and a second side surface that face each other in a direction parallel to the coil axis, and a third side surface and a fourth side surface that face each other in a direction in which the plurality of unit coils are adjacent to each other; <1> ~ <9> 10. The inductor according to claim 9, wherein [Explanation of symbols]

[0090] 10. Body (insulating layer) 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h Insulation layer 11 First aspect 12 Second aspect 13 Third aspect 14 Fourth aspect 15 Top 16 Bottom 20 coils 21, 21A, 21B, 21C unit coil 21a, 21Aa, 21Ba, 21Ca 1st end 21b, 21Ab, 21Bb, 21Cb 2nd end 21Ac, 21Bc, 21Cc inner circumference 22 Connection 23A First lead conductor 23B Second lead-out conductor 24, 24a, 24b, 24c, 24d, 24e, 24f coil conductor layers 25, 25a, 25b, 25c, 25d, 25e, 25f, 25g, 25h Via conductor 100, 101, 200 inductors CA Coil Axis P positive direction N negative direction

Claims

1. The base body and a coil provided inside the element body, the coil is configured by connecting a plurality of unit coils in series, each unit coil being wound in a spiral shape along a coil axis, The plurality of unit coils are arranged adjacent to each other in the same direction so that the coil axes of each unit coil are parallel to each other, adjacent unit coils are connected in series by connecting first ends located in the positive direction of the coil axis or second ends located in the negative direction of the coil axis, An inductor in which the winding direction of all the unit coils is the same when viewed from the coil axis.

2. The inductor according to claim 1 , wherein the coil is configured by connecting an odd number of the unit coils in series.

3. The inductor according to claim 2 , wherein the coil is configured by connecting three of the unit coils in series.

4. 4. The inductor according to claim 3, wherein, when viewed from the coil axis, an area enclosed by an inner periphery of the unit coil arranged at the center is equal to the sum of areas enclosed by the inner peripheries of the unit coils arranged at both ends.

5. 4. The inductor according to claim 3, wherein, when viewed from the coil axis, the area enclosed by the inner periphery of the unit coil arranged at the center is equal to the area enclosed by the inner periphery of the unit coil arranged at one end, and is also equal to the area enclosed by the inner periphery of the unit coil arranged at the other end.

6. The inductor according to claim 1 , wherein the coil is configured by connecting an even number of the unit coils in series.

7. The inductor according to claim 6 , wherein the coil is configured by connecting two of the unit coils in series.

8. 8. The inductor according to claim 7, wherein, when viewed from the coil axis, an area enclosed by an inner periphery of one of the unit coils is equal to an area enclosed by an inner periphery of the other unit coil.

9. the element body is configured by stacking a plurality of insulating layers in a direction parallel to the coil axis, 9. The inductor according to claim 1, wherein each of the unit coils is formed by electrically connecting a plurality of coil conductor layers stacked together with the insulating layer in a direction parallel to the coil axis.

10. The inductor according to any one of claims 1 to 8, wherein the element body is a rectangular parallelepiped having a first side and a second side that face each other in a direction parallel to the coil axis, and a third side and a fourth side that face each other in a direction in which the plurality of unit coils are adjacent to each other.

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