Coil component

Abstract

To provide a coil component capable of preventing damage caused by thermal deformation by suppressing the thermal deformation of a conductor.SOLUTION: A coil component includes a base body made of a magnetic material, a pair of external electrodes respectively provided on surfaces of the base body facing each other, and a conductor connected to each of the pair of external electrodes and extending from one of the external electrodes to the other inside the base body, wherein the conductor has a projection on a surface in contact with the base body.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a coil component, and more particularly to a coil component having a plurality of inductor elements and used for being built into a substrate. [Background technology]

[0002] As described in Patent Document 1, a known coil component has a configuration including a chip body (substrate) made of a magnetic material, a conductor embedded in the chip body so as to be exposed from both opposing end faces of the chip body, and a pair of external electrodes electrically connected to the exposed portions of the conductor. In the configuration described in Patent Document 1, the conductors are arranged so as to extend from one opposing external electrode to the other.

[0003] Also known is a component-embedded substrate, in which electronic components such as coil components are embedded in the substrate. By embedding multiple coil components in the substrate, electronic components such as coil components can be mounted at a high density.

[0004] In a component-embedded board, the external electrodes of electronic components such as coil components are electrically connected to wiring through via conductors. The via conductors are formed by sealing the coil component placed in a cavity formed in an insulating layer of a printed circuit board with resin, irradiating the external electrodes of the resin-encapsulated coil component with a laser to form via holes, exposing the external electrodes, and then plating the via holes. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-144526 Summary of the Invention [Problem to be solved by the invention]

[0006] When a coil component is exposed to temperature changes, the conductor may thermally expand or contract more than the substrate due to the difference in thermal expansion coefficient between the conductor and the substrate. Here, because the substrate has high rigidity, the presence of the substrate suppresses thermal expansion or contraction (hereinafter also referred to as thermal deformation) in the portion of the conductor surrounded by the substrate. However, the ends of the conductor are exposed from the surface of the substrate and are prone to thermal expansion or contraction because the substrate does not function to suppress thermal deformation. As a result, damage such as cracks may occur near the ends of the conductor, in the external electrodes connected to the conductor, or in the wiring connected to the external electrodes.

[0007] In particular, when a substrate made of metallic magnetic material particles made of soft magnetic material is used, magnetic saturation is less likely to occur than in a substrate made of ferrite, and so it has high superposition characteristics and is used in circuits through which large currents flow. Therefore, the amount of heat generated by the application of current is large.

[0008] As described in Patent Document 1, when a conductor has a conductor extending from one of opposing external electrodes to the other, the effect of the base body in suppressing thermal deformation is less likely to work in the opposing direction, making the conductor more susceptible to thermal expansion or contraction. Therefore, the possibility of damage due to thermal deformation of the conductor increases in an environment with temperature changes. In particular, in the case of coil components incorporated in component-embedded substrates, the coil components are susceptible to the heat from other elements within the substrate, making the above-mentioned thermal deformation problem more likely to occur.

[0009] An object of the present disclosure is to provide a coil component that can suppress thermal deformation of a conductor due to temperature changes and prevent damage caused by thermal deformation. [Means for solving the problem]

[0010] One aspect of the present disclosure is a coil component comprising a base made of a magnetic material, external electrodes provided on opposing surfaces of the base, and conductors connected to each of the external electrodes and extending from one side of the external electrodes to the other side inside the base, the conductors having a convex portion on the surface that contacts the base. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a coil component that can suppress thermal deformation of a conductor due to temperature changes and prevent damage caused by thermal deformation. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view of a coil component according to a first embodiment. [Figure 2] FIG. 2 is a partially enlarged cross-sectional view taken along line II in FIG. [Figure 3] FIG. 3 is an enlarged view of a portion II of FIG. [Figure 4] FIG. 4 is a cross-sectional view of the conductor taken along line III-III in FIG. [Figure 5] FIG. 10 is a diagram for explaining a preferred height of a convex portion. [Figure 6] 2 is a partially enlarged cross-sectional view of a coil component according to a second embodiment taken along line II in FIG. 1. FIG. [Figure 7] FIG. 7 is an enlarged view of a portion IV in FIG. [Figure 8] FIG. 8 is a cross-sectional view taken along line VV in FIG. 7. [Figure 9] 10 is a diagram showing a part of a cross section along the YZ plane of a coil component according to a modified example. FIG. [Figure 10] 10 is a diagram showing a part of a cross section along the XY plane of a coil component according to a modified example. FIG. [Figure 11] 1 is a cross-sectional view of a component-embedded substrate including a coil component, taken in the thickness direction. [Figure 12] 10A to 10C are diagrams for explaining a method for manufacturing a coil component by a lamination process. [Figure 13] 10A to 10C are diagrams for explaining a method for manufacturing a coil component by a lamination process. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited thereto. In this specification and drawings, components having substantially the same functional configurations may be designated by the same reference numerals to avoid redundant description. The drawings are schematic diagrams shown to facilitate understanding of the present disclosure and are not necessarily drawn to scale. In the drawings, mutually orthogonal X-, Y-, and Z-axes are shown as axes defining a fixed coordinate system for the coil component. In this specification, the extension direction of the X-axis is also referred to as the X-direction, the extension direction of the Y-axis as the Y-direction, and the extension direction of the Z-axis as the Z-direction.

[0014] First Embodiment (Basic structure of coil parts) First, the basic structure of a coil component 1 according to the present disclosure will be described. Fig. 1 is a perspective view of the coil component 1 according to the first embodiment. Fig. 2 is a partially enlarged cross-sectional view taken along line II in Fig. 1. Fig. 3 is an enlarged view of portion II in Fig. 2. Note that Fig. 1 also serves as a perspective view of a second embodiment, which will be described later.

[0015] The coil component shown in Figures 1 to 3 is suitable for use as an inductor component. The coil component is also used in a component-embedded wiring board. Furthermore, a wiring board on which the coil component 1 of this embodiment is mounted is suitable for use in electronic devices such as smartphones, tablets, game consoles, servers, and automotive electrical equipment.

[0016] As shown in FIGS. 1 and 2 , a coil component 1 includes a base 10, a pair of external electrodes 20 provided on opposing surfaces of the base 10, and a conductor 130 connected to each of the pair of external electrodes 20 and extending inside the base 10. The base 10, the pair of external electrodes 20, and the conductor 130 form one inductor element 5. In the example shown in FIGS. 1 and 2 , the coil component 1 is provided with four conductors 130, which are electrically independent. The coil component 1 is an array-type inductor component (inductor array) in which four inductor elements 5, each including one conductor 130, are formed. However, the number of inductor elements included in the coil component according to the embodiment of the present disclosure is not limited to four. That is, the coil component 1 may include one inductor element, or may include multiple inductor elements other than four. Including multiple inductor elements in a coil component is advantageous in that multiple inductor elements can be simultaneously mounted in a single operation of mounting one coil component, thereby reducing the complexity of the mounting operation. Furthermore, since there is no need to adjust the relative positions of a plurality of inductor elements, the reliability of the wiring board on which the coil components are mounted and embedded can be improved.

[0017] 1, four inductor elements 5 are arranged in a row in the Y direction, but if the coil device 1 includes multiple inductor elements 5, the multiple inductor elements 5 may be arranged two-dimensionally. That is, multiple element rows each consisting of multiple inductor elements 5 arranged in one direction may be arranged in a direction perpendicular to the one direction.

[0018] As shown in FIG. 1, the base 10 may have a generally rectangular parallelepiped shape. The base 10 may have six surfaces that define its outer surface, specifically, a first main surface 10a, a second main surface 10b, a first side surface 10c, a second side surface 10d, a first end surface 10e, and a second end surface 10f. The first main surface 10a and the second main surface 10b face each other, the first side surface 10c and the second side surface 10d face each other, and the first end surface 10e and the second end surface 10f face each other. The areas of the first main surface 10a and the second main surface 10b are larger than the areas of the first side surface 10c, the second side surface 10d, the first end surface 10e, and the second end surface 10f. When the coil component 1 is provided on a substrate to form a wiring board, the coil component 1 is arranged so that the planar direction (direction along the XY plane) along the first main surface 10a or the second main surface 10b is aligned with the planar direction of the substrate.

[0019] As shown in FIGS. 1 and 2, the direction in which the first main surface 10a and the second main surface 10b face each other (the direction in which the main surfaces 10a and 10b face each other) is the Z direction. The direction in which the first side surface 10c and the second side surface 10d face each other (the direction in which the side surfaces 10c and 10d face each other) is the X direction, and the direction in which the first end surface 10e and the second end surface 10f face each other (the direction in which the end surfaces 10e and 10f face each other) is the Y direction. In FIGS. 1 and 2, since the first main surface 10a is located on the upper side of the base 10, the first main surface 10a is sometimes referred to as the "upper surface" and the second main surface 10b is sometimes referred to as the "lower surface." The vertical direction of the base 10 is also referred to as the height direction and is the Z direction in the drawings. The longitudinal direction of the base 10 is also referred to as the length direction and is the Y direction in the drawings. Furthermore, the direction perpendicular to both the height direction (Z direction) and the length direction (Y direction) is also called the width direction, and is defined as the X direction in the drawings.

[0020] In Fig. 1, each of the faces 10a to 10f of the base 10 is shown as a flat surface, but each of the faces 10a to 10f may be a curved surface. Furthermore, each of the faces 10a to 10f is shown as being perpendicular to the adjacent faces, but each of the faces 10a to 10f does not necessarily have to be perpendicular to the adjacent faces. Furthermore, each vertex of the base 10 may be rounded, and the ridge lines of the base 10 (lines indicating the boundaries between adjacent faces among the faces 10a to 10f) may not be straight, but may be curved depending on the shape and arrangement of each of the faces 10a to 10f.

[0021] The height of the base 10, i.e., the distance between the opposing first main surface 10a and second main surface 10b (dimension in the Z direction), may be 0.5 mm or more and 2 mm or less. The width of the base 10, i.e., the distance between the opposing first side surface 10c and second side surface 10d (dimension in the X direction), may be 0.5 mm or more and 10 mm or less. The length of the base 10, i.e., the distance between the opposing first end surface 10e and second end surface 10f (dimension in the Y direction), may be 2 mm or more and 20 mm or less. The dimension of the base 10 in the Z direction may be smaller than the dimensions in the X direction and the Y direction. The dimensions of the coil device 1 are the dimensions of the base 10 plus the external electrodes 20, and are approximately equal to the above-mentioned dimensions of the base 10.

[0022] The substrate 10 is made of a magnetic material, and more specifically, contains metal magnetic particles. Furthermore, the substrate 10 may be a composite magnetic material containing metal magnetic particles and a binder, i.e., a metal composite. The substrate 10 made of a metal composite is obtained, for example, by pressure molding a slurry obtained by kneading a composite magnetic material containing metal magnetic particles and a resin binder (also called a resin binder).

[0023] The metal magnetic particles contained in the substrate 10 may be a mixture of one type or multiple types of metal magnetic particles. The metal magnetic particles contained in the substrate 10 may contain one or more of iron (Fe), nickel (Ni), and cobalt (Co). Specific examples of materials constituting the metal particles include Fe, Fe-Ni alloy, Fe-Co alloy, Fe-Si alloy, Fe-Si-Al alloy, Fe-Si-Cr alloy, Fe-Si-Al-Cr alloy, Fe-Si-Cr-B alloy, and Fe-Si-Cr-BC. These metal magnetic particles can be used alone or in a mixture of two or more types to form mixed particles.

[0024] The cross-sectional shape of the metal magnetic particles may be circular, elliptical, or a modified form of these. The average particle size of the metal magnetic particles contained in the base 10 may be preferably 1 μm or more and 20 μm or less, more preferably 2 μm or more and 10 μm or less. In this specification, the average particle size of the particles may be the average particle size (median diameter (D50)) calculated from the volume-based particle size distribution measured based on scanning electron microscope (SEM) images.

[0025] The binder contained in the substrate 10 may be an organic binder, an inorganic binder, or both. Resins, particularly thermosetting resins with excellent insulating properties, are preferred as organic binders. Specific examples of resin materials for binders include epoxy resins, polyimide resins, polystyrene (PS) resins, high-density polyethylene (HDPE) resins, polyoxymethylene (POM) resins, polycarbonate (PC) resins, polyvinylidene fluoride (PVDF) resins, phenolic resins, polytetrafluoroethylene (PTFE) resins, and polybenzoxazole (PBO) resins. Inorganic binders include inorganic oxides such as BO, NaO, SiO, ZnO, and PbO, as well as glass. The binders described above may be used singly or in combination.

[0026] The proportion of the metal magnetic particles to the entire substrate 10 may be 80% by volume or more. The proportion of the binder to the entire substrate 10 may be 3% by volume or more. The substrate 10 may contain voids, but the proportion of the voids to the entire substrate 10 may be less than 2% by volume.

[0027] 1 and 2, the external electrode 20 includes a first external electrode 20a and a second external electrode 20b that are spaced apart from each other. In the example shown in FIGS. 1 and 2, the first external electrode 20a is provided on the first main surface 10a of the base 10, and the second external electrode 20b is provided on the second main surface 10b of the base 10. Therefore, the first external electrode 20a and the second external electrode 20b face each other in the opposing direction of the main surfaces 10a and 10b, i.e., in the Z direction. The first external electrode 20a is connected to one end of the conductor 130, and the second external electrode 20b is connected to the other end of the conductor 130.

[0028] The external electrodes 20 are provided only on opposing surfaces of the base 10 and are connected to the ends of the conductors 130. In the case of FIGS. 1 and 2, the external electrodes 20 are provided on the first main surface 10a and the second main surface 10b of the base 10.

[0029] As shown in FIG. 3 , the external electrode 20 may include a first portion 21 formed on the outermost side, and a second portion 22 located inside the first portion 21 and inward in the Z direction from the main surfaces (the first main surface 10a and the second main surface 10b) of the base 10. By forming the external electrode 20 to include the first portion 21 and the second portion 22, a sufficient thickness can be ensured. Furthermore, the first portion 21 may be formed to cover the second portion 22. Although not shown in FIGS. 1 to 3 , an insulating layer that is flush with the second portion 22 may be disposed on the periphery of the second portion 22. The dimensions of the base 10 and the coil component 1 described above may be the dimensions when the insulating layer is disposed.

[0030] The thickness (length in the Z direction) of the external electrode 20 may be 15 μm or more and 30 μm or less. When the external electrode 20 includes the first portion 21 and the second portion 22, the above thickness is the total thickness of the first portion 21 and the second portion 22 combined. The thickness of the first portion 21 may be 5 μm or more and 20 μm or less. The thickness of the second portion 22 may be 10 μm or more and 30 μm or less.

[0031] The external electrode 20 may contain one or more of silver (Ag), copper (Cu), nickel (Ni), and alloys thereof. The first portion 21 and the second portion 22 may be made of the same material or different materials.

[0032] 1 and 2, the conductor 130 is embedded in the base 10 and is disposed so that both ends thereof are exposed from the first main surface 10a and the second main surface 10b of the base 10. The exposed both ends of the conductor 130 are connected to the first external electrode 20a and the second external electrode 20b, respectively. Note that in FIG. 1, protrusions 135 formed on the conductor 130 are not shown.

[0033] Furthermore, the conductor 130 is arranged so as to extend from the first external electrode 20a arranged on the first main surface 10a toward the second external electrode 20b arranged on the second main surface 10b, or so as to extend from the second external electrode 20b arranged on the second main surface 10b toward the first external electrode 20a arranged on the first main surface 10a. In other words, the conductor 130 extends along the opposing direction in which the first main surface 10a and the second main surface 10b face each other, i.e., along the Z direction, or the conductor 130 is embedded so as to penetrate through the base 10 in the Z direction. Note that in this specification, "along a predetermined direction" not only means that the extending direction coincides with the predetermined direction, but also includes a direction that deviates from the predetermined direction and forms an angle with respect to the predetermined direction, preferably no more than 10°, more preferably no more than 5°.

[0034] In the examples shown in FIGS. 1 to 3, the conductor 130 may be linearly arranged within the base 10. Here, "linearly" arranged" means that the central axis CA (FIG. 3) of the conductor is arranged along the opposing direction (Z direction) in which the first main surface 10a and the second main surface 10b oppose each other, preferably such that the direction of the central axis CA (FIG. 3) of the conductor coincides with the opposing direction (Z direction). Within the base 10, the conductor 130 may include a curved portion or may partially include a wound portion. Note that when the conductor 130, preferably the entire conductor 130, is linearly arranged, opposing external electrodes can be connected using the shortest conductor length, thereby reducing the DC resistance of the coil component.

[0035] The conductor 130 may include one or more of silver (Ag), copper (Cu), nickel (Ni), and alloys thereof. The conductor 130 may be formed by applying a conductor-forming material (such as a conductive paste) using plating, screen printing, or the like.

[0036] (Specific configuration of conductor) Next, the conductor 130 according to an embodiment of the present disclosure will be described in more detail. In addition to Figures 1 to 3, Figure 4 shows a cross-sectional view taken along line III-III in Figure 3.

[0037] As shown in FIGS. 2 to 4 , the conductor 130 in this embodiment has a convex portion 135 formed on the surface that contacts the base 10. The convex portion 135 is a portion that protrudes from the peripheral surface of the core portion 134 of the conductor 130 in a direction perpendicular to the Z direction, i.e., along the X-Y plane. While FIGS. 2 and 3 show a cross section of the conductor 130 taken along the Z-Y plane including the central axis CA, the convex portion 135 may be observed in a cross section of the conductor 130 cut along any Z direction, even if the cross section is not taken along the Z-Y plane or does not include the central axis CA. The presence of the convex portion 135 in the conductor 130 can be confirmed, for example, by observing an arbitrary cross section of the coil device 1 cut along the Z direction of the conductor 130 with a microscope or the like.

[0038] When an electronic device incorporating a coil component is in use, the coil component is exposed to temperature changes due to factors such as heat generation from elements included in the electronic device. Among the components constituting the coil component, the conductor has a relatively high thermal expansion coefficient and is therefore more susceptible to thermal expansion or thermal contraction (hereinafter also referred to as thermal deformation) than the base. Because the base has high rigidity, the thermal deformation of the conductor is suppressed in the area surrounded by the base, but is more likely to occur in areas not in contact with the base, i.e., the ends of the conductor exposed from the base. Furthermore, as shown in FIGS. 1 and 2 , when the conductor extends along the opposing direction (Z direction) in which the first and second main surfaces 10a and 10b of the base face each other, the effect of suppressing thermal deformation of the conductor in the opposing direction (Z direction) inside the base is weakened, and the amount of thermal deformation in the opposing direction may be large. This may result in loads being applied to the periphery of the end of the conductor 130, for example, to the external electrode 20 connected to the conductor 130, which may cause damage such as cracks or peeling between components. More specifically, damage may occur to the external electrodes 20 connected to the conductors 130, or to the wiring or the like connected to the external electrodes 20 when the coil component 1 is built into a substrate.

[0039] In contrast, according to this embodiment, the peripheral surface of the conductor 130 is not smooth as in the prior art, but has a protrusion 135 on the surface that comes into contact with the base 10. The protrusion 135 is a portion that protrudes in a direction perpendicular to the facing direction (Z direction) and is a portion that bites into the base 10, so that the base 10 penetrates into the upper or lower side or both sides of the protrusion 135 (FIG. 3). This makes it possible to suppress thermal deformation of the conductor 130 in the vertical direction (i.e., in the facing direction or Z direction) at the position of the protrusion 135. More specifically, by having the base 10 intrude into the side closer to the main surfaces (first main surface 10a and / or second main surface 10b) of the protrusions 135 in the Z direction, deformation of the conductor 130 due to thermal expansion can be effectively suppressed, and by having the base 10 intrude into the side farther from the main surfaces (first main surface 10a and / or second main surface 10b) of the protrusions 135 in the Z direction, deformation of the conductor 130 due to thermal contraction can be effectively suppressed. The configuration according to this embodiment, which exhibits such an effect of suppressing thermal deformation by the protrusions 135, is particularly suitable for coil components 1 including conductors 130 arranged in a straight line (conductors 130 with no curved or wound portions) that are prone to thermal deformation.

[0040] The number of protrusions 135 formed on one conductor 130 may be one or more, counted along the Z direction. As shown in Figures 2 and 3, when multiple protrusions 135 are formed on one conductor 130 along the Z direction, the effect of suppressing thermal deformation of the conductor 130 can be improved. As shown in Figures 2 and 3, the multiple protrusions 135 do not have to be regularly arranged along the Z direction. In other words, the pitch between the protrusions 135 does not necessarily have to be constant.

[0041] Here, as shown in FIG. 2 , the coil device 1 or the base 10 is divided into two equal parts along the Z direction, namely, an upper portion Pza and a lower portion Pzb. When a plurality of convex portions 135 are formed along the Z direction, it is preferable that at least one convex portion 135 is formed in the upper portion Pza and at least one convex portion 135 is formed in the lower portion Pzb. In other words, when the conductor 130 is divided into regions spanning the upper portion Pza and the lower portion Pzb, at least one convex portion 135 is formed in the section spanning the upper portion Pza of the conductor 130, and at least one convex portion 135 is formed in the section spanning the lower portion Pzb of the conductor 130. By forming at least one convex portion 135 in each of the upper portion Pza and the lower portion Pzb, the effect of suppressing thermal deformation of the conductor 130 in the up-down direction (Z direction) can be improved in each of the upper portion Pza and the lower portion Pzb. As described above, the conductor 130 is exposed from the base 10, and the areas where thermal deformation of the conductor 130 is likely to occur are on both the first main surface 10a side (upper side) and the second main surface 10b side (lower side), so damage to the external electrode 20 or the wiring connected to the external electrode 20 can be prevented at each of these locations.

[0042] As described above, the locations where thermal deformation of the conductor 130 is likely to occur are the ends of the conductor 130 where the conductor 130 is exposed from the base 10 and where the base 10 is less likely to suppress deformation, so it is preferable that the convex portions 135 be formed in positions closer to the ends of the conductor 130. This configuration can effectively suppress thermal deformation. Therefore, for example, it is preferable that at least one convex portion 135 is formed in the upper portion of the portion obtained by further dividing the upper portion Pza into two equal parts, and at least one convex portion 135 is formed in the lower portion of the portion obtained by further dividing the lower portion Pzb into two equal parts.

[0043] 2 and 3, it is preferable that the protrusions 135 are directly connected to the external electrodes 20. In other words, it is preferable that the protrusions 135 are formed on the ends of the conductors 130 that are exposed from the base 10. This makes it possible to suppress thermal deformation of the conductors 130, particularly deformation during thermal contraction, and to prevent damage to the wiring that may occur in or around the coil component 1.

[0044] 3, the external electrode 20 may be formed so as to cover the entire conductor 130, including the protrusion 135. In other words, when viewed from above, that is, when viewed in the direction toward the surface of the base 10 on which the external electrode 20 is provided, the conductor 130 is provided within the range of the external electrode 20. Note that, when the external electrode 20 includes a first portion 21 and a second portion 22, it is preferable that both the first portion 21 and the second portion 22 are formed so as to cover the entire conductor 130.

[0045] Furthermore, as shown in FIG. 4, the protrusions 135 may be formed on the entire peripheral surface of the conductor 130. In other words, the protrusions 135 form a closed ring when viewed in a cross section perpendicular to the Z direction or in a cross section along the XY plane. However, the protrusions 135 may be formed only partially when viewed along the peripheral surface of the conductor 130. Furthermore, multiple protrusions 135 may be formed spaced apart in the circumferential direction of the conductor 130. When multiple protrusions 135 are formed along the peripheral surface of the conductor 130, it is preferable that the multiple protrusions 135 be arranged point-symmetrically about the central axis CA. This allows the effect of suppressing thermal deformation of the conductor 130 to be obtained in a balanced manner along the peripheral surface.

[0046] 4, the contour shape of the convex portion 135 is circular when viewed in a cross section of the conductor 130 cut in a direction perpendicular to the Z direction. The contour shape of the cross section of the core portion 134 is also circular, and the entire core portion 134 may be roughly cylindrical. As described above, in this embodiment, when viewed in a cross section of the conductor 130 cut in a direction perpendicular to the Z direction, the contour shape of the convex portion 135 and the contour shape of the cross section of the core portion 134 may be similar, for example, may be similar shapes. Note that the contour shape of the convex portion 135 and the contour shape of the cross section of the core portion 134 are arbitrary and may be different, as described below.

[0047] The size of the protrusions 135 is not particularly limited as long as it can suppress thermal deformation of the conductor 130 in the direction in which the first principal surface 10a and the second principal surface 10b oppose each other (the Z direction). However, the height d (FIG. 3) of the protrusions 135, i.e., the extension distance in the direction perpendicular to the Z direction (the direction along the XY plane), is preferably greater than the average particle size of the metal magnetic particles contained in the base 10. When the conductor 130 attempts to expand or contract, the protrusions 135 exert a force from below or above on the base 10 above or below it. However, by having the height d of the protrusions 135, a sufficient distance can be secured to withstand such forces. This improves the suppression of thermal deformation of the conductor 130 in the vertical direction. The height d of the protrusions 135 can be the protruding distance of the protrusions 135 as viewed in a cross section cut to include the central axis CA of the conductor 130.

[0048] When viewed in a cross section cut along the Z direction including the central axis CA, the shape of the protrusion 135 may be, for example, a substantially triangular shape, with the length (width) in the Z direction decreasing with increasing distance from the central axis CA of the conductor 130, as shown in FIG. 3 . Such a shape is preferable because it allows the height d of the protrusion 135 to be increased with a smaller volume. The shape of the protrusion 135 is not limited and may be, for example, a polygon including quadrangles such as rectangles, trapezoids, and parallelograms, as well as a semicircle, semiellipse, or the like. When the cross section of the protrusion 135 cut along the Z direction is polygonal, the corners may be rounded. Furthermore, the apex of the protrusion 135, i.e., the apex of the portion protruding in a direction perpendicular to the Z direction or along the XY plane, may be flat or pointed. When multiple protrusions 135 are formed on one conductor 130, they may have different shapes depending on their location.

[0049] The height d of the protrusion 135 may be preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 80 μm or less. When the height d is 5 μm or more, the strength or rigidity of the portions of the base 10 that are above and below the protrusion 135 is increased, thereby improving the effect of suppressing thermal deformation of the conductor 130 in the vertical direction. When the height d is 100 μm or less, the shape of the peripheral surface of the conductor 130 becomes complex, and electrical distance between adjacent conductors is ensured, preventing defects such as short circuits. When multiple protrusions 135 are formed and the heights of the respective protrusions 135 are different, the height d of the protrusions 135 is an average value.

[0050] The height d of the protrusions 135 is preferably defined as follows in relation to the diameter of the metal magnetic particles contained in the base 10. FIG. 5 is a schematic enlarged view of portion A in FIG. 3. As shown in FIG. 5, if the metal magnetic particles MP (shown by dotted lines) are closely packed on at least one of the upper and lower sides of the protrusions 135, and the metal magnetic particles MP are arranged in at least three layers in the direction along the XY plane, it is believed that sufficient strength against thermal deformation of the conductor 130 will be ensured. Therefore, it is preferable that the height d of the protrusions 135 be 5.46r or greater, where r is the average particle size (radius) of the metal magnetic particles. The specific numerical range of the height d of the protrusions 135 described above is set in consideration of the preferred average particle size of the metal magnetic particles in this embodiment.

[0051] Furthermore, the width w of the protrusion 135, more specifically, the Z-direction length of the protrusion 135, may be preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 30 μm or less. By having the width w within this range, the protrusion 135 can be more reliably embedded in the base 10, thereby improving the effect of suppressing thermal deformation of the conductor 130 in the vertical direction. The width w of the protrusion 135 may be the Z-direction distance from the start point to the end point of the protrusion 135 in the Z direction, as viewed in a cross section cut to include the central axis CA of the conductor 130. The start point and end point of the protrusion 135 are both points where the slope of the tangent to the outline of the protrusion 135 becomes zero on the side closer to the central axis CA. However, in the case of a protrusion 135 formed at the end of the conductor 130, the start point or end point of the protrusion 135 may be the position of the end face of the conductor 130. When a plurality of convex portions 135 are formed and the widths of the convex portions 135 are different from one another, the width w of the convex portions 135 is set to the average value.

[0052] The cross section (cut in a direction perpendicular to the central axis CA) of the core portion 134 of the conductor 130 may have an equivalent circle diameter (the diameter of a circle having the same area) of 30 μm or more and 200 μm or less. The diameter of the cross section of the core portion 134 can determine the electrical characteristics of the conductor 130, including the DC resistance of the conductor 130.

[0053] Second Embodiment Furthermore, a second embodiment will be described with reference to FIGS. 6 and 7. A coil component 201 according to the second embodiment differs from the coil component 1 according to the first embodiment in that the conductor configuration is different. Other configurations are the same as those of the first embodiment, and therefore description thereof will be omitted. Definitions of terms are also the same as those described in the first embodiment. FIG. 6 is a partially enlarged view of the cross section of line II in FIG. 1 for the coil component 201 according to the second embodiment. FIG. 7 is an enlarged view of a portion IV in FIG. 2. FIG. 8 is a cross section of line VV in FIG. 7.

[0054] The coil component 201 has a base 10, a pair of external electrodes 20 provided on opposing surfaces of the base 10, and a conductor 230 connected to each of the pair of external electrodes 20 and extending inside the base 10. In this embodiment, four conductors 230 are also formed within the coil component 201 as shown in Fig. 6, and four inductor elements 5 are formed by the base 10, the pair of external electrodes, and the conductors 230.

[0055] Furthermore, as in the first embodiment, in the second embodiment, the conductor 230 is arranged so as to extend from the first external electrode 20a arranged on the first main surface 10a toward the second external electrode 20b arranged on the second main surface 10b, or from the second external electrode 20b arranged on the second main surface 10b toward the first external electrode 20a arranged on the first main surface 10a. That is, it extends along the opposing direction (Z direction) in which the first main surface 10a and the second main surface 10b oppose each other. The overall appearance of the coil component 201 is similar to that of the coil component 1 according to the first embodiment, and therefore a perspective view of the coil component 201 is omitted.

[0056] Furthermore, the conductor 230 has protrusions 235 formed on the surface that contacts the base 10. In the second embodiment, a plurality of protrusions 235 are also formed along the Z direction, but as shown in Fig. 7, the size and shape of each protrusion 235 and the pitch of the protrusions 235 in the Z direction are uniform. Furthermore, when viewed in a cross section cut along the Z direction including the central axis CA, the shape of the protrusions 235 is rectangular.

[0057] In the coil device 201 according to the second embodiment, the conductor 230 is also provided with the protrusions 235, which allow the protrusions 235 to dig into the base 10 in a direction perpendicular to the facing direction (Z direction), and the base 10 fits into the upper or lower side or both sides of the protrusions 235. This makes it possible to suppress thermal deformation of the entire conductor 230, including the protrusions 235, in the vertical direction, i.e., in the facing direction (Z direction), as described in the first embodiment. This reduces the possibility of damage to the periphery of the end of the conductor 230, for example, to the external electrode 20 or the wiring connected to the external electrode 20, which may occur due to thermal deformation.

[0058] Furthermore, the height d of the protrusions 235, i.e., the extension distance in the direction perpendicular to the Z direction, i.e., the direction along the XY plane, is preferably greater than the average particle size of the metal magnetic particles contained in the base 10. This ensures that the protrusions 235 have a sufficient distance to withstand the force applied to the base 10 in the vertical direction when the protrusions 235 expand or contract, thereby improving the suppression of thermal deformation in the vertical direction of the conductor 230. The height d of the protrusions 235 can be the average value of the heights of multiple protrusions. The specific range of the height d of the protrusions 235 in the second embodiment may be the same as the height d of the protrusions 135 in the first embodiment.

[0059] 8, when viewed in a cross section cut along a direction perpendicular to the Z direction (along the XY plane), the contour shape of the cross section of the protrusion 235 of the conductor 230 is approximately square, more specifically, a square with rounded corners. Similarly, the cross section of the core portion 234 is also a square with rounded corners. In this way, the contour shape of the cross section of the protrusion 235 and the cross section of the core portion 2134 may be the same or similar shapes.

[0060] 9 and 10 show a modified example of the conductor 130 of this embodiment as a modified example of the first embodiment. FIG. 9 is a cross-sectional view taken along the Z direction at a position including the central axis CA of the conductor 130, and corresponds to FIG. 3. As shown in FIG. 9, in a cross-section taken along the Z direction including the central axis CA, the upper contour of the protrusion 135 extends along the Y direction, and the lower contour of the protrusion 135 extends at an angle along the Y direction. This gives the protrusion 135 a substantially triangular cross-sectional shape. Furthermore, the multiple protrusions 135 are formed without any gaps between them, i.e., the end point of one protrusion 135 is in contact with the start point of the adjacent protrusion 135. This arrangement of the protrusions 135 allows the base 10 that fits between the protrusions 135 to have the same size and shape as the protrusions 135 when viewed in a cross-section taken along the Z direction. In other words, the base 10 that fits between the protrusions 135 also has a substantially triangular shape. This allows the base 10 to firmly fix the convex portion 135 of the conductor 130 in the vertical direction (Z direction), improving the effect of suppressing thermal deformation of the conductor 130 in the vertical direction (Z direction).

[0061] FIG. 10 is a cross-sectional view of the conductor 130 taken in a direction perpendicular to the Z direction (a direction along the XY plane), and corresponds to FIG. 4. As shown in FIG. 10(a), the cross-sectional shape of the core portion 134 is circular, but the contour shape of the protrusions 135 may be substantially square, more specifically, a square with rounded corners. Also, as shown in FIG. 10(b), the cross-sectional shape of the core portion 134 is circular, but the contour shape of the protrusions 135 may be substantially triangular, more specifically, a triangular shape with arc-shaped corners. In the embodiment shown in FIGS. 10(a) and 10(b), the height of the protrusions 135 varies depending on the location when viewed along the circumference, and has a maximum height value dmax and a minimum height value dmin.

[0062] <Coil component embedded board> The coil component 1 or coil component 201 described above can be built into a substrate to provide a component-embedded wiring substrate (also referred to as a coil component-embedded substrate). Fig. 11 shows a schematic diagram of a coil component-embedded substrate 80 having a coil component 1 built in, as an example. The coil component-embedded substrate 80 can be formed, for example, by placing the coil component 1 in a through hole 81a formed in a substrate 81, sealing the substrate with resin, forming via holes by irradiating a laser toward the external electrodes 20 to expose the external electrodes 20, and plating the via holes to connect wiring 83 to the external electrodes 20 of the coil component 1. Thereafter, the coil component 1 is sealed with sealing resin 82 on both the first main surface 10a and the second main surface 10b.

[0063] Compared to component-mounted wiring boards in which coil components are mounted on the main surface of the board, this type of coil component-embedded substrate 80 has the advantage of being more compact because it allows elements to be arranged three-dimensionally, including in the thickness direction. Furthermore, the length of the connected wiring can be shortened, reducing power distribution loss and contributing to power savings in electronic devices equipped with the coil components. However, since the coil components are arranged closer to elements such as CPUs, a more precise and less wasteful structure is required. Furthermore, because the coil components are closer to elements such as CPUs, they are more susceptible to heat from the elements and are more exposed to temperature changes. Therefore, a configuration that can suppress thermal deformation of the conductors due to temperature changes is required. Therefore, the embodiments of the present disclosure (including the first and second embodiments) are suitable for use in coil component-embedded wiring boards.

[0064] <Manufacturing method for coil components> The method for manufacturing a coil component according to the present disclosure is not particularly limited, and any known manufacturing process for coil components such as a lamination process, a thin film process, etc. Below, a method for manufacturing a coil component by a lamination process will be described as a representative example.

[0065] 12 and 13 show a manufacturing method using a lamination process. The lamination process is suitable, for example, as a method for manufacturing the coil component 1 according to the first embodiment. In the lamination process, first, a magnetic sheet 71, which is a precursor of the base-forming sheet that constitutes the base 10, is produced (FIG. 12(a1)). The magnetic sheet 71 can be obtained, for example, by kneading a metal magnetic material with a resin to produce a slurry, applying this slurry to a plastic base film by a method such as a doctor blade method, drying it, and cutting it to a predetermined size.

[0066] Next, through holes 71a are formed in predetermined positions of the magnetic sheet 71, penetrating the magnetic sheet 71 in the thickness direction (FIG. 12(a2)). A conductive paste is then printed on the upper surface of the magnetic sheet with the through holes 71a formed therein by a method such as screen printing, thereby filling the through holes 71a formed in the magnetic sheet with the conductive paste 130A, and producing a main body forming sheet 75 (FIG. 12(a3)). By varying the size and / or shape of the through holes 71a formed in the main body forming sheet 75, a plurality of main body forming sheets 75 with different sizes and / or shapes of the conductive paste (conductor forming material) 130A are formed. The size and / or shape of the through holes 71a formed in the plurality of main body forming sheets 75 are designed so that, when the plurality of main body forming sheets 75 are stacked (FIG. 13(a)), a convex portion 135 (FIG. 13(b)) protruding in a direction perpendicular to the Z direction is formed in the conductor 130.

[0067] On the other hand, as shown in Figures 12(b1) to (b3), an outermost portion forming sheet 77 is prepared for forming the outermost portion including the external electrodes 20. On the main body forming sheet 75 (Figure 12(a3)) obtained as shown in Figures 12(a1) to (a3), second portions 22 of the external electrodes 20 are formed by screen printing or the like using a conductive paste (Figure 12(b2)). Furthermore, insulating layers 73 are formed by screen printing or the like using an insulating paste between the second portions 22 so as to be flush with the second portions 22, thereby forming the outermost portion forming sheet 77 (Figure 12(b3)).

[0068] A plurality of the obtained main body forming sheets 75 are stacked in the Z direction of the coil component 201 to be obtained, and outermost portion forming sheets 77 are stacked on the uppermost and lowermost sides in the Z direction (FIG. 13(a)). The obtained laminate may be thermocompression bonded using a press. Next, the laminate is cut into pieces of the desired size using a cutting machine such as a dicing machine, thereby obtaining a cut laminate. The cut laminate may be subjected to polishing treatment such as barrel polishing, if necessary.

[0069] Next, the individualized laminate is degreased and heat-treated to obtain the base 10. This heat treatment forms an oxide layer on the surface of each soft magnetic metal powder contained in the magnetic sheet, and adjacent soft magnetic metal powder particles are bonded together via the oxide layer. The heat treatment of the chip laminate is performed, for example, at a heating temperature of 600°C to 800°C for a heating time of 20 to 120 minutes.

[0070] Next, the first portions 21 of the external electrodes 20 are formed by plating or the like, and the coil component 201 is obtained (FIG. 13(b)).

[0071] Although the lamination process described above is a method of laminating sheets having main surfaces aligned with the XY planes of the coil component along the Z direction, the coil component can also be manufactured by a process of laminating sheets having main surfaces aligned with the YZ planes of the coil component along the X direction, or a process of laminating sheets having main surfaces aligned with the XZ planes of the coil component along the Y direction. Also, although a thin-film process has been given as an example suitable for manufacturing the coil component 201 according to the second embodiment, and a lamination process has been given as an example suitable for manufacturing the coil component 201 according to the first embodiment, the lamination process may be used to manufacture the coil component 201, or the thin-film process used to manufacture the coil component 1 may also be used.

[0072] The thin-film process is suitable, for example, as a method for manufacturing the coil component 1 according to the first embodiment. In the thin-film process, a positive resist obtained by developing a photoresist is plated with a conductor material, and then the positive resist is removed to form multiple conductors having predetermined protrusions according to this embodiment. The conductors thus obtained are embedded in a base material, and after undergoing individual division, degreasing, and heat treatment, external electrodes are further formed by plating to obtain the coil component.

[0073] Although specific embodiments have been described above in detail, the present disclosure is not limited to the above embodiments. Furthermore, the above embodiments can be subject to various changes, modifications, substitutions, additions, deletions, and combinations within the scope of the claims.

[0074] Aspects of the present disclosure are, for example, as follows.

[0075] <1> a base made of a magnetic material; a pair of external electrodes respectively provided on opposing surfaces of the substrate; a conductor connected to each of the pair of external electrodes and extending from one of the external electrodes to the other within the base body, The conductor has a protrusion on a surface that contacts the base.

[0076] <2> the conductor has an upper portion and a lower portion that are divided into two equal parts along a direction facing the pair of external electrodes, the conductor has two or more protrusions, At least one of the protrusions is formed in the upper portion and at least one of the protrusions is formed in the lower portion. <1> The coil component according to claim 1.

[0077] <3> the base contains metal magnetic particles, and when viewed in a cross section cut along the opposing direction, the size of the protrusions in a direction perpendicular to the opposing direction of the surface of the base is larger than the average diameter of the metal magnetic particles; <1> or <2> The coil component according to claim 1.

[0078] <4> the conductor is provided within the range of the external electrode when viewed in a direction toward the surface of the base on which the external electrode is provided. <1> from <3> The coil component according to any one of the above items.

[0079] <5> the external electrodes are directly connected to the protrusions. <1> from <4> The coil component according to any one of the preceding claims.

[0080] <6> It is a component built into the board. <1> or <2> The coil component according to claim 1. [Explanation of symbols]

[0081] 1 Coil parts 10 Base 10a 1st main surface (top surface) 10b 2nd principal surface (bottom surface) 10c 1st side 10d 2nd side 10e 1st end face 10f 2nd end face 20 External electrode 20a 1st external electrode 20b 2nd external electrode 21 1st part (outer part) 22 Second part (inner part) 81 Circuit Board 81a Through hole 82 Sealing resin 83 Wiring 80 Component embedded board 130, 230 conductor 134, 234 core part 135, 235 convex part

Claims

1. a base made of a magnetic material; a pair of external electrodes respectively provided on opposing surfaces of the substrate; a conductor connected to each of the pair of external electrodes and extending from one of the external electrodes to the other within the base body, The conductor has a protrusion on a surface that contacts the base.

2. the conductor has an upper portion and a lower portion that are divided into two equal parts along a direction facing the pair of external electrodes, the conductor has two or more protrusions, The coil component according to claim 1 , wherein at least one of the protrusions is formed in the upper portion and at least one of the protrusions is formed in the lower portion.

3. the substrate comprises metal magnetic particles; 3. The coil component according to claim 1, wherein, when viewed in a cross section taken along the direction in which the surfaces of the base face each other, the size of the protrusions protruding in a direction perpendicular to the direction in which the surfaces of the base face each other is greater than the average diameter of the metal magnetic particles.

4. 3. The coil component according to claim 1, wherein the conductor is provided within the range of the external electrodes when viewed in a direction toward the surface of the base on which the external electrodes are provided.

5. The coil component according to claim 1 , wherein the external electrodes are directly connected to the protrusions.

6. The coil component according to claim 1 or 2, which is a component built into a substrate.

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