Coil component

Abstract

To provide a coil component in which a surface of an external electrode has improved smoothness.SOLUTION: A coil component according to one embodiment of the present invention comprises: a base having a first surface; a first coil conductor provided inside the base; a first external electrode provided at least on the first surface of the base; and a second external electrode provided at least on the first surface of the base. On the first surface of the base, the second external electrode is provided at a position located away in a first direction from the first external electrode. The first external electrode is connected to one end of the coil conductor, and the second external electrode is connected to the other end of the coil conductor. The first external electrode has a first plating layer, and the second external electrode has a second plating layer. Viewed from a normal direction of the first surface of the base, the first external electrode has a shape without any corners. Viewed from the normal direction of the first surface of the base, the second external electrode has a shape without any corners.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The disclosure herein relates to a coil component. [Background technology]

[0002] Coil components are passive elements used in electronic devices. For example, coil components are used to remove noise from power lines or signal lines. The coil components include a base, a coil conductor provided inside the base with its end face exposed from the base, and an external electrode connected to the end face of the coil conductor.

[0003] A coil component-embedded substrate is known in which electronic components including coil components are embedded in a substrate. In a coil component-embedded substrate, multiple coil components can be embedded in the substrate, allowing the coil components to be mounted at high density. A conventional coil component-embedded substrate in which a coil component is embedded in a substrate is described in JP 2023-065654 A (Reference 1) (see, in particular, FIG. 8 and the description thereof).

[0004] In a coil component-embedded substrate having a built-in coil component, the external electrodes of the coil component 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 Publication No. 2023-065654 Summary of the Invention [Problem to be solved by the invention]

[0006] Many coil components are intended to be surface-mounted on a substrate. Coil components are surface-mounted on a substrate by joining external electrodes to rectangular lands provided on the surface of the substrate. In this context, the external electrodes of coil components are configured to have a rectangular shape when viewed from the normal direction of the mounting surface in order to ensure reliable bonding with the lands. An example of external electrodes that are rectangular when viewed from the mounting surface is shown as terminal electrodes 41 and 42 in FIG. 1A of Cited Document 1. As shown in FIG. 8 of Cited Document 1, conventionally, coil components equipped with rectangular external electrodes 41 and 42 are embedded in a coil component-embedded substrate.

[0007] The external electrodes of coil components are formed by applying a rectangular base electrode layer to at least the mounting surface of a magnetic substrate and then plating the base electrode layer. This base electrode layer is formed so that it has a rectangular shape when viewed from the mounting surface. When plating is performed on this rectangular base electrode layer, a strong electric field is generated in the areas near the corners of the rectangle, which promotes plating growth in the areas near the corners of the base electrode layer more than in other areas. As a result, the film thickness of the external electrodes formed by plating is thicker near the corners than in other areas. Therefore, the surface of the external electrodes of conventional coil components has irregularities corresponding to the degree of plating growth. These irregularities reduce the smoothness of the external electrode surface.

[0008] When surface-mounting a coil component, the coil component is joined to the substrate with solder, so even if the external electrode surface is not smooth, there is almost no problem with mounting. For this reason, until now, little attention has been paid to the smoothness of the external electrode surface.

[0009] The inventor discovered that when a coil component having external electrodes with low surface smoothness is embedded in a substrate, the laser irradiated to form a via hole is diffusely reflected by the surface of the external electrode, and this diffusely reflected laser light hits the side wall of the via hole, widening the width of the via hole beyond the specified width, resulting in the problem that the via conductor cannot be formed accurately.

[0010] One object of the present invention is to provide a coil component having improved surface smoothness of external electrodes. Other objects of the present invention will become apparent throughout the entire specification. The inventions disclosed in this specification may solve problems that are understood from sources other than those described in the "Problem to be Solved by the Invention" section. The various inventions disclosed in this specification may be collectively referred to as "the present invention." [Means for solving the problem]

[0011] A coil component according to one aspect of the present invention comprises a base having a first surface, a first coil conductor provided inside the base, a first external electrode provided at least on the first surface of the base, and a second external electrode provided at least on the first surface of the base. The second external electrode is provided on the first surface of the base at a position spaced apart from the first external electrode in a first direction. The first external electrode is connected to one end of the coil conductor, and the second external electrode is connected to the other end of the coil conductor. The first external electrode has a first plating layer, and the second external electrode has a second plating layer. The first external electrode has a shape without corners when viewed from the normal direction of the first surface of the base. The second external electrode has a shape without corners when viewed from the normal direction of the first surface of the base. [Effects of the Invention]

[0012] According to one aspect of the present invention, the smoothness of the surface of the external electrode can be improved compared to an external electrode that has corners in a plan view. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view schematically showing a coil component 1 according to one embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of the coil device 1 of FIG. [Figure 3] 2 is an enlarged cross-sectional view showing a part of the cross section of the coil device 1 of FIG. 1 taken along line II. [Figure 4] 2 is a schematic plan view of an external electrode included in the coil device of FIG. 1. FIG. [Figure 5] FIG. 10 is a schematic plan view of an external electrode included in a conventional coil component. [Figure 6a] 5A to 5C are diagrams schematically illustrating a part of a process for manufacturing a coil component-embedded substrate according to one embodiment. [Figure 6b] 5A to 5C are diagrams schematically illustrating a part of a process for manufacturing a coil component-embedded substrate according to one embodiment. [Figure 6c] 5A to 5C are diagrams schematically illustrating a part of a process for manufacturing a coil component-embedded substrate according to one embodiment. [Figure 6d] 5A to 5C are diagrams schematically illustrating a part of a process for manufacturing a coil component-embedded substrate according to one embodiment. [Figure 6e] 5A to 5C are diagrams schematically illustrating a part of a process for manufacturing a coil component-embedded substrate according to one embodiment. [Figure 6f] 5A to 5C are diagrams schematically illustrating a part of a process for manufacturing a coil component-embedded substrate according to one embodiment. [Figure 7] FIG. 1 is a perspective view schematically illustrating a coil device 101 according to another embodiment of the present invention. [Figure 8] FIG. 8 is a plan view of the coil device 101 of FIG. [Figure 9] FIG. 10 is a plan view schematically showing a modified example of the external electrode. [Figure 10] FIG. 10 is a plan view schematically showing another modified example of the external electrode. DETAILED DESCRIPTION OF THE INVENTION

[0014] Various embodiments of the present invention will be described below with appropriate reference to the drawings. Components common to multiple drawings are designated by the same or similar reference numerals throughout the drawings. Please note that the drawings are not necessarily drawn to scale for the sake of convenience. The embodiments described below do not necessarily limit the invention according to the claims. Elements described in the following embodiments are not necessarily essential to the solution of the invention.

[0015] 1 First embodiment (coil component 1) 1-1 Basic structure of coil component 1 Various embodiments disclosed in this specification relate to a coil component built into a coil component-embedded substrate. A coil component 1 according to a first embodiment of the present invention will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a perspective view schematically showing the coil component 1, Fig. 2 is a plan view of the coil component 1, and Fig. 3 is a schematic cross-sectional view showing an enlarged portion of the cross section of the coil component 1 taken along line II.

[0016] For ease of explanation, each figure may include an L axis, a W axis, and a T axis that are perpendicular to each other. In this specification, the dimensions, arrangement, shape, and other features of each component of the coil device 1 may be explained based on the L axis, W axis, and T axis. In this specification, the dimension of each component in the T axis direction may be referred to as the "thickness dimension."

[0017] The coil component 1 is used in an electronic circuit, for example, to remove noise. The coil component 1 may be a power inductor incorporated in a power supply line, or an inductor used in a signal line. As will be described later, the coil component 1 may be built into a substrate.

[0018] The coil component 1 includes a base 10, a coil conductor 25 provided inside the base 10, a first external electrode 21 provided on the surface of the base 10, and a second external electrode 22 provided on the surface of the base 10 at a position spaced apart from the first external electrode 21. The first external electrode 21 is electrically connected to one end of the coil conductor 25, and the second external electrode 22 is electrically connected to the other end of the coil conductor 25. The first external electrode 21 is disposed so as to be spaced apart from the second external electrode 22 in the L-axis direction.

[0019] The coil conductor 25 can have various shapes depending on the type of coil component 1. The coil conductor 25 is configured to have a shape that generates a desired inductance. For example, the coil conductor 25 is wound a predetermined number of turns around the coil axis. One end and the other end of the coil conductor are connected to the first external electrode 21 and the second external electrode, respectively.

[0020] The base 10 may contain multiple soft magnetic metal particles bonded together. The soft magnetic metal particles are coated with an insulating film. If the insulating film on the surface of the soft magnetic metal particles is damaged, the insulation resistance of the base 10 formed by bonding the soft magnetic metal particles will decrease. For this reason, an insulating layer may be provided on the surface of the base 10 in the region between the first external electrode 21 and the second external electrode 22. The insulating layer may be formed from a resin with excellent insulating properties. This insulating film can increase the insulation resistance between the first external electrode 21 and the second external electrode 22 on the surface of the base 10. In one embodiment, the base 10 may be configured to have a rectangular parallelepiped shape. In this specification, the terms "rectangular parallelepiped" and "rectangular parallelepiped shape" do not necessarily mean "rectangular parallelepiped" in the strict mathematical sense. The base 10 has an upper surface 10a, a lower surface 10b, a first end surface 10c, a second end surface 10d, a first side surface 10e, and a second side surface 10f. These six faces define the outer surface of the base body 10. The upper face 10a is perpendicular to the T-axis direction.

[0021] In one embodiment, the first external electrode 21 and the second external electrode 22 are both provided on the base 10 so as to be in contact with at least the upper surface 10a. The first external electrode 21 and the second external electrode 22 may both be in contact with only the upper surface 10a of the outer surface of the base 10.

[0022] A resin film may be provided on the upper surface 10a of the base 10 so as to cover the periphery of each of the first external electrode 21 and the second external electrode 22. The resin film can improve the insulation properties of the first external electrode 21 and the second external electrode 22.

[0023] 1-2 First external electrode 21 and second external electrode 22 The first external electrode 21 has a first base electrode layer 21A and a first plating layer 21B covering the first base electrode layer 21A. The second external electrode 22 has a second base electrode layer 22A and a second plating layer 22B covering the second base electrode layer 22A.

[0024] The first and second underlying electrode layers 21A and 22A are formed, for example, by applying a paste-like conductive material to the surface of the substrate 10 and then curing the applied conductive material. Examples of conductive materials that can be used for the first and second underlying electrode layers 21A and 22A include metal materials such as copper (Cu), nickel (Ni), silver (Ag), palladium (Pd), and gold (Au), as well as alloy materials containing one or more of these metal materials. An example of such an alloy material is a Cu-Ni alloy.

[0025] The first plating layer 21B is formed on the surface of the first base electrode layer 21A by, for example, electrolytic plating, so as to cover the first base electrode layer 21A. The first plating layer 21B extends along the conductive first base electrode layer 21A to the edges of the first base electrode layer 21A. Therefore, when the coil device 1 is viewed from above (in other words, when viewed from the normal direction of the upper surface 10a (i.e., the direction along the T-axis in the illustrated embodiment)), the shape of the first plating layer 21B is equal to or similar to the shape of the first base electrode layer 21A. The second plating layer 22B is formed on the surface of the second base electrode layer 22A by, for example, electrolytic plating, so as to cover the second base electrode layer 22A. The second plating layer 22B extends along the conductive second base electrode layer 22A to the edges of the second base electrode layer 22A. Therefore, when the coil component 1 is viewed from above, the shape of the second plating layer 22B is equal to or similar to the shape of the second base electrode layer 22A. At least one of the first plating layer 21B and the second plating layer 22B may have a two-layer structure. When the first plating layer 21B has a two-layer structure, the first plating layer in contact with the first base electrode layer 21A may be a nickel plating layer, and the second plating layer formed on the first plating layer may be a tin plating layer. When the second plating layer 22B has a two-layer structure, the first plating layer in contact with the second base electrode layer 22A may be a nickel plating layer, and the second plating layer formed on the first plating layer may be a tin plating layer. The outermost layers of the first plating layer 21B and the second plating layer 22B may be Cu plating layers.

[0026] The first external electrode 21 has an upper surface 21a, a lower surface 21b, a first end surface 21c, a second end surface 21d, a first side surface 21e, and a second side surface 21f. The outer surface of the first external electrode 21 is defined by these six surfaces.

[0027] The second external electrode 22 has an upper surface 22a, a lower surface 22b, a first end surface 22c, a second end surface 22d, a first side surface 22e, and a second side surface 22f. The outer surface of the second external electrode 22 is defined by these six surfaces.

[0028] The first external electrode 21 is provided on the base 10 so that the lower surface 21b is in contact with the upper surface 10a of the base 10. The second external electrode 22 is provided on the base 10 so that the lower surface 22b is in contact with the upper surface 10a of the base 10. As shown in Fig. 3, the first external electrode 21 is provided so that the second end surface 21d thereof faces the first end surface 22c of the second external electrode 22 in the L-axis direction.

[0029] The shapes of the first external electrode 21 and the second external electrode 22 in a plan view will be described with particular reference to Fig. 2. As shown in Fig. 2, when the coil device 1 is viewed in a plan view, the first external electrode 21 has a shape without any corners. In the embodiment shown in Fig. 2, the outer edge of the first external electrode 21 has an oval shape. More specifically, the outer edge of the first external electrode 21 is defined by a first straight line portion L11 extending linearly along the W-axis, a second straight line portion L12 extending linearly along the L-axis, a third straight line portion L13 extending linearly along the W-axis, a fourth straight line portion L14 extending linearly along the L-axis, a first corner portion C11 connecting the first straight line portion L11 and the second straight line portion L12 and curving, a second corner portion C12 connecting the second straight line portion L12 and the third straight line portion L13 and curving, a third corner portion C13 connecting the third straight line portion L13 and the fourth straight line portion L14 and curving, and a fourth corner portion C14 connecting the fourth straight line portion L14 and the first straight line portion L11 and curving. The outer edge of the first external electrode 21 has multiple linearly extending portions, but these linearly extending portions are not connected directly to each other but are connected via curved corners, so that there are no corners where two straight lines intersect on the outer edge of the first external electrode 21. The first linear portion L11, a portion of the first corner portion C11, and a portion of the fourth corner portion C14 correspond to the first end face 21c. The second linear portion L12, a portion of the first corner portion C11, and a portion of the second corner portion C12 correspond to the first side face 21e. The third linear portion L13, a portion of the second corner portion C12, and a portion of the third corner portion C13 correspond to the second end face 21d. The fourth linear portion L14, a portion of the third corner portion C13, and a portion of the fourth corner portion C14 correspond to the second side face 21f.

[0030] When the coil device 1 is viewed from above, the second external electrode 22 has a shape without corners, similar to the first external electrode 21. The shape of the second external electrode 22 in a plan view may be the same as the shape of the first external electrode 21 in a plan view. In the embodiment shown in FIG. 2 , the outer edge of the second external electrode 22 is defined by a first straight line portion L21 extending linearly along the W-axis, a second straight line portion L22 extending linearly along the L-axis, a third straight line portion L23 extending linearly along the W-axis, a fourth straight line portion L24 extending linearly along the L-axis, a first corner portion C21 connecting the first straight line portion L21 and the second straight line portion L22 and curved, a second corner portion C22 connecting the second straight line portion L22 and the third straight line portion L23 and curved, a third corner portion C23 connecting the third straight line portion L23 and the fourth straight line portion L24 and curved, and a fourth corner portion C24 connecting the fourth straight line portion L24 and the first straight line portion L21 and curved. The outer edge of the second external electrode 22 has multiple linearly extending portions, but these linearly extending portions are not directly connected to each other but are connected via curved corners, so that there are no corners where two straight lines intersect on the outer edge of the second external electrode 22. The first linear portion L21, a portion of the first corner portion C21, and a portion of the fourth corner portion C24 correspond to the first end face 22c. The second linear portion L22, a portion of the first corner portion C21, and a portion of the second corner portion C22 correspond to the first side face 22e. The third linear portion L23, a portion of the second corner portion C22, and a portion of the third corner portion C23 correspond to the second end face 22d. The fourth linear portion L24, a portion of the third corner portion C23, and a portion of the fourth corner portion C24 correspond to the second side face 22f.

[0031] The first external electrode 21 is positioned so that the second end face 21d faces the first end face 22c of the second external electrode 22, and therefore, in a planar view, the third straight line portion L13 of the first external electrode 21 faces the first straight line portion L21 of the second external electrode 22 in the L-axis direction.

[0032] In one embodiment, the first external electrode 21 is configured so that the circularity of the outer edge in a plan view is equal to or greater than 0.8 and less than 1. When the first plating layer 21B is formed by electrolytic plating, the higher the circularity of the outer edge of the first base electrode layer 21A in a plan view, the more uniform the electric field strength on the surface of the first base electrode layer 21A becomes. For this reason, it is desirable that the circularity of the first base electrode layer 21A in a plan view (i.e., the circularity of the outer edge of the first external electrode 21) is high. On the other hand, if the circularity of the outer edge of the first external electrode 21 in a plan view is high, the distance between the first external electrode 21 and the second external electrode 22 becomes shorter, assuming that the area of ​​the first external electrode 21 in a plan view is constant. For this reason, it is desirable to set an upper limit to the circularity of the outer edge in a plan view. In one embodiment, the upper limit of the circularity of the outer edge of the first external electrode 21 (and the first base electrode layer 21A) in a plan view may be 0.95.

[0033] Similar to the first external electrode 21, the second external electrode 22 is configured so that the circularity of the outer edge in a plan view is equal to or greater than 0.8 and less than 1. The upper limit of the circularity of the outer edge of the second external electrode 22 in a plan view may be 0.95.

[0034] The first external electrode 21 and the second external electrode 22 are designed and manufactured to have an area equal to or greater than a predetermined area in order to ensure the bonding strength with the coil conductor 25 and to reduce electrical resistance. If the first external electrode 21 and the second external electrode 22 are circular (circularity = 1), and if the areas of the first external electrode 21 and the second external electrode 22 are both equal to or greater than a predetermined area that satisfies design requirements, the distance between the first external electrode 21 and the second external electrode 22 will be short, making it more likely that a short circuit will occur between the first external electrode 21 and the second external electrode 22. In one aspect of the present invention, both the first external electrode 21 and the second external electrode 22 have straight portions that extend linearly in a plan view, so that the distance between the first external electrode 21 and the second external electrode 22 can be made larger than when the first external electrode 21 and the second external electrode 22 are circular. 2, the third straight line portion L13 of the first external electrode 21 and the first straight line portion L21 of the second external electrode 22 are arranged to face each other in the L-axis direction, so the distance between the first external electrode 21 and the second external electrode 22 can be made larger than when the first external electrode 21 and the second external electrode 22 are formed in a circular shape in a plan view or when the first external electrode 21 and the second external electrode 22 have curved surfaces that protrude toward each other. This makes it possible to prevent short circuits from occurring between the first external electrode 21 and the second external electrode 22.

[0035] As described above, the first plating layer 21B of the first external electrode 21 is formed by electrolytic plating on the surface of the first base electrode layer 21A. By forming the first base electrode layer 21A so that it has a shape without corners in a plan view, it is possible to prevent the electric field from concentrating in a certain region of the first base electrode layer 21A during the plating process. This makes it possible to uniformize the size of the crystal grains formed by the plating process in the first plating layer 21B. By a similar mechanism, it is possible to uniformize the size of the crystal grains formed by the plating process in the second plating layer 22B as well.

[0036] Next, a first external electrode 21 provided in a coil component 1 according to one embodiment of the present invention will be compared with an external electrode 1021 provided in a conventional coil component, with reference to Figures 4 and 5. Figure 4(a) is a schematic diagram showing the first external electrode 21 in a plan view, and Figure 4(b) is a cross-sectional view showing the cross section of the first external electrode 21 taken along line AA in Figure 4(a). Figure 5(a) is a schematic diagram showing the external electrode 1021 in a plan view, and Figure 5(b) is a cross-sectional view showing the cross section of the external electrode 1021 taken along line BB in Figure 5(a).

[0037] As described above, the first external electrode 21 provided in the coil component 1 has a shape without corners in a plan view. In contrast, the external electrode 1021 provided in a conventional coil component has a rectangular shape in a plan view, as shown in FIG. 5(a). An external electrode having a rectangular shape is shown, for example, in FIG. 5A of Japanese Patent Application Laid-Open No. 2023-065654. Conventional external electrodes are formed to have a rectangular shape in a plan view due to ease of fabrication and the fact that the shape of the land to which they are joined during surface mounting is standardized to a rectangular shape.

[0038] The external electrode 1021 is fabricated by forming a plating layer 1021B on a rectangular base electrode layer 1021A. When forming the plating layer on the rectangular base electrode layer 121A, a strong electric field is generated near the corners, resulting in protrusions 1021B1 where the plating has grown excessively near the corners, as shown in Fig. 5(b). Thus, when the plating layer 1021B is formed on the rectangular base electrode layer 1021A, the plating that grows excessively near the corners reduces the smoothness of the surface of the external electrode 1021.

[0039] On the other hand, the first external electrode 21 has a shape without corners in a plan view. Therefore, when forming the first plating layer 21B provided on the first external electrode 21, the generation of a strong electric field in some regions on the first base electrode layer 21A is suppressed, and excessive plating growth in some regions can be suppressed. Therefore, as shown in Fig. 4(b), the surface of the first external electrode 21, which has a shape without corners in a plan view, can be formed smoother than the surface of the conventional external electrode 1021, which has a shape with corners in a plan view.

[0040] The arithmetic surface roughness Ra of the upper surface 21a of the first external electrode 21 is, for example, in the range of 1 to 3 μm. The maximum waviness height Wz of the upper surface 21a of the first external electrode 21 is, for example, in the range of 10 μm or less. The arithmetic surface roughness Ra and the maximum waviness height Wz described herein are both measured in accordance with Japanese Industrial Standard JIS B 0601:2013. The arithmetic surface roughness Ra and the maximum waviness height Wz can be measured using a one-shot 3D shape measuring instrument VR-6200 manufactured by Keyence Corporation. The maximum waviness height Wz of a conventional external electrode 1021 having a shape with corners in plan view is 10 μm or more due to the uneven strength of the electric field applied when forming the external electrode 1021 by electroplating. In contrast, the maximum waviness height Wz of a first external electrode 21 having a shape without corners in plan view can be within the range of 10 μm. In this way, by forming the first external electrode 21 so that it has a shape without corners in a plan view, it is possible to make the surface of the external electrode 21 smoother. The circularity of the first base electrode layer 21A is desirably high, and specifically, as described above, it is desirably equal to or greater than 0.8 and less than 1. By increasing the circularity of the first base electrode layer 21A, it is possible to form a first external electrode 21 that is smoother and has less waviness.

[0041] For simplicity of illustration, only the first external electrode 21 is shown in FIG. 4, but the above description of the first external electrode 21 also applies to the second external electrode 22 unless a contradiction occurs.

[0042] 1-3 Manufacturing method for substrate with built-in coil components Next, an example of a method for manufacturing a coil component built-in substrate that incorporates the coil component 1 will be described with reference to FIGS. 6a to 6f.

[0043] First, as shown in FIG. 6a, an insulating layer 52 is formed on a film 51, and a cavity H1 is formed in the insulating layer 52. Then, the coil component 1 is placed in the cavity H1 so that the first external electrode 21 and the second external electrode 22 contact the film 51. The film 51 is a film for temporarily attaching the coil component 1 in the manufacturing process of the coil component-embedded substrate. The insulating layer 52 is part of a multilayer printed circuit board. Although not shown, multiple wiring patterns and via conductors connecting the wiring patterns may be formed inside the insulating layer 52. The insulating layer 52 is made of an insulating material such as glass epoxy. The material of the insulating layer 52 is not limited to glass epoxy, and various materials suitable for insulating layers in multilayer printed circuit boards may be used.

[0044] Next, as shown in FIG. 6b, a first resin layer 53 is formed in the cavity H1 in which the coil component 1 is placed so as to cover the coil component 1. The first resin layer 53 is made of, for example, a thermosetting resin. The first resin layer 53 may be formed by injecting uncured thermosetting resin into the cavity H1 and heating and curing the injected thermosetting resin. In this way, an intermediate body is produced in which the coil component 1 is sealed in the cavity H1 by the first resin layer 53.

[0045] 6c, the intermediate body is turned upside down, and then the film 51 is removed. A second resin layer 54 is formed on the upper surface of the intermediate body from which the film 51 has been removed. The second resin layer 54 may be made of the same thermosetting resin as the first resin layer 53. The second resin layer 54 is formed so as to cover the first external electrode 21 and the second external electrode 22 that are exposed when the film 51 is removed.

[0046] Next, as shown in FIG. 6d, first via holes VH1 and second via holes VH2 are formed in the second resin layer 54 to expose a portion of the first external electrode 21 and a portion of the second external electrode 22. The first via holes VH1 are formed by irradiating a laser beam from above the paper toward the first external electrode 21. Similarly, the second via holes VH2 are formed by irradiating a laser beam from above the paper toward the second external electrode 22. The irradiated laser is, for example, a carbon dioxide laser. By using two carbon dioxide laser processing machines, the laser can be simultaneously irradiated toward the upper surface 21 a of the first external electrode 21 and the upper surface 22 a of the second external electrode 22, so that the first via holes VH1 and the second via holes VH2 can be formed in parallel. This shortens the manufacturing time.

[0047] As described above, the first external electrode 21 and the second external electrode 22 have a shape without corners in a plan view, and therefore the respective upper surfaces 21a and 22a are smoother than those of conventional external electrodes. Therefore, diffuse reflection of the laser irradiated toward the first external electrode 21 and the second external electrode 22 to form the first via holes VH1 and the second via holes VH2 is suppressed from the upper surfaces 21a and 22a, thereby enabling the first via holes VH1 and the second via holes VH2 to be formed with high precision. Furthermore, a Cu plating layer may be provided on the outermost layer of each of the first external electrode 21 and the second external electrode 22. By providing the Cu plating layer on the outermost layer of each of the first external electrode 21 and the second external electrode 22, the connectivity between the first external electrode 21 and the second external electrode 22 and the substrate can be improved, and deformation of the surfaces of the first external electrode 21 and the second external electrode 22 when the first external electrode 21 and the second external electrode 22 are irradiated with the laser can be suppressed.

[0048] 6e, the bottom and wall surfaces defining the first via hole VH1 and the bottom and wall surfaces defining the second via hole VH2 are plated to form via conductors 61 in the first via hole VH1 and via conductors 62 in the second via hole VH2. In addition, the surface of the second resin layer 54 is plated to form a conductor layer 70 on the surface of the second resin layer 54.

[0049] Next, as shown in Figure 6f, the region of the conductor layer 70 between the first external electrode 21 and the second external electrode 22 in the L-axis direction is etched to form a first wiring pattern 71 connected to the first external electrode 21 and a second wiring pattern 72 connected to the second external electrode 22.

[0050] In this manner, a coil component built-in substrate 81 in which the coil component 1 is embedded is produced.

[0051] In addition to the illustrated coil component 1, various electronic components may be built into the coil component-built-in substrate 81. The electronic components other than the coil component 1 built into the coil component-built-in substrate 81 may be passive elements such as inductors, capacitors, resistors, etc., or active elements such as semiconductor ICs.

[0052] The coil component built-in substrate 81 can be mounted in various electronic devices, including smartphones, tablets, game consoles, automotive electrical components, servers, and various other electronic devices.

[0053] 2 Second embodiment (coil component 101) Next, a coil component 101 according to a second embodiment will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is a perspective view of the coil component 101 according to the second embodiment, and Fig. 8 is a plan view of the coil component 101. The coil component 101 differs from the coil component 1 that has two external electrodes in that the coil component 101 has eight external electrodes 121 to 128.

[0054] The coil component 101 is, for example, an array-type element in which multiple elements are packaged inside the base 110. In an array-type element, multiple elements are packaged as a single element, which reduces the mounting space required for packaging multiple elements. In the coil component 101, four coil components 1 described in the first embodiment are arranged in the W-axis direction, and these four coil components are packaged as a single element. Different types of elements may be packaged in the coil component 101. For example, the coil component 101 may be configured by packaging four elements selected from an LC filter, an LCR filter, and an inductor inside the base 110. The coil component 101 may be configured by packaging four elements of the same type inside the base 110. For example, the coil component 101 may be an array-type inductor in which four inductor elements are packaged. The coil component 101 may also include an element connected to more than two external electrodes, such as a magnetically coupled inductor (e.g., a common mode choke coil).

[0055] Each of the external electrodes 121 to 128 may be in contact with only the upper surface 110a of the outer surface of the base 110. The external electrode 121 is connected to one end of a first coil conductor (not shown), and the external electrode 122 is connected to the other end of the first coil conductor. The external electrode 123 is connected to one end of a second coil conductor (not shown), and the external electrode 124 is connected to the other end of the second coil conductor. The external electrode 125 is connected to one end of a third coil conductor (not shown), and the external electrode 126 is connected to the other end of the third coil conductor. The external electrode 127 is connected to one end of a fourth coil conductor (not shown), and the external electrode 128 is connected to the other end of the fourth coil conductor. The first coil conductor, the second coil conductor, the third coil conductor, and the fourth coil conductor may each be configured similarly to the coil conductor 25 provided in the coil component 1.

[0056] Each of the external electrodes 121 to 128 has a base electrode layer and a plating layer covering the base electrode layer, similar to the first external electrode 21. This plating layer is formed by, for example, electrolytic plating.

[0057] The regions of the upper surface 110a of the base 110 that are not covered by the external electrodes 121 to 128 may be covered with an insulating layer. The insulating layer may be made of a resin with excellent insulating properties.

[0058] Each of the external electrodes 121 to 128 may be formed in the same shape as the first external electrode 21 or the second external electrode 22 when viewed from above. More specifically, as shown in Fig. 8, when the coil device 101 is viewed from above, all of the external electrodes 121 to 128, and the first external electrode 21, may have a shape without corners.

[0059] In the embodiment shown in FIG. 8 , the outer edge of the external electrode 121 is defined by a first straight line portion L111 extending linearly along the L axis, a second straight line portion L112 extending linearly along the W axis, a third straight line portion L113 extending linearly along the L axis, a fourth straight line portion L114 extending linearly along the W axis, a first corner portion C111 connecting the first straight line portion L111 and the second straight line portion L112 and curved, a second corner portion C112 connecting the second straight line portion L112 and the third straight line portion L113 and curved, a third corner portion C113 connecting the third straight line portion L113 and the fourth straight line portion L114 and curved, and a fourth corner portion C114 connecting the fourth straight line portion L114 and the first straight line portion L111 and curved.

[0060] The outer edge of the external electrode 122 is defined by a first straight line portion L121 extending linearly along the L axis, a second straight line portion L122 extending linearly along the W axis, a third straight line portion L123 extending linearly along the L axis, a fourth straight line portion L124 extending linearly along the W axis, a first corner portion C121 connecting the first straight line portion L121 and the second straight line portion L122 and curving, a second corner portion C122 connecting the second straight line portion L122 and the third straight line portion L123 and curving, a third corner portion C123 connecting the third straight line portion L123 and the fourth straight line portion L124 and curving, and a fourth corner portion C124 connecting the fourth straight line portion L124 and the first straight line portion L121 and curving.

[0061] The outer edge of the external electrode 123 is defined by a first straight line portion L131 extending linearly along the L axis, a second straight line portion L132 extending linearly along the W axis, a third straight line portion L133 extending linearly along the L axis, a fourth straight line portion L134 extending linearly along the W axis, a first corner portion C131 connecting the first straight line portion L131 and the second straight line portion L132 and curving, a second corner portion C132 connecting the second straight line portion L132 and the third straight line portion L133 and curving, a third corner portion C133 connecting the third straight line portion L133 and the fourth straight line portion L134 and curving, and a fourth corner portion C134 connecting the fourth straight line portion L134 and the first straight line portion L131 and curving.

[0062] The outer edge of the external electrode 124 is defined by a first straight line portion L141 extending linearly along the L axis, a second straight line portion L142 extending linearly along the W axis, a third straight line portion L143 extending linearly along the L axis, a fourth straight line portion L144 extending linearly along the W axis, a first corner portion C141 connecting the first straight line portion L141 and the second straight line portion L142 and curving, a second corner portion C142 connecting the second straight line portion L142 and the third straight line portion L143 and curving, a third corner portion C143 connecting the third straight line portion L143 and the fourth straight line portion L144 and curving, and a fourth corner portion C144 connecting the fourth straight line portion L144 and the first straight line portion L141 and curving.

[0063] The outer edge of the external electrode 125 is defined by a first straight line portion L151 extending linearly along the L axis, a second straight line portion L152 extending linearly along the W axis, a third straight line portion L153 extending linearly along the L axis, a fourth straight line portion L154 extending linearly along the W axis, a first corner portion C151 connecting the first straight line portion L151 and the second straight line portion L152 and curving, a second corner portion C152 connecting the second straight line portion L152 and the third straight line portion L153 and curving, a third corner portion C153 connecting the third straight line portion L153 and the fourth straight line portion L154 and curving, and a fourth corner portion C154 connecting the fourth straight line portion L154 and the first straight line portion L151 and curving.

[0064] The outer edge of the external electrode 126 is defined by a first straight line portion L161 extending linearly along the L axis, a second straight line portion L162 extending linearly along the W axis, a third straight line portion L163 extending linearly along the L axis, a fourth straight line portion L164 extending linearly along the W axis, a first corner portion C161 connecting the first straight line portion L161 and the second straight line portion L162 and curving, a second corner portion C162 connecting the second straight line portion L162 and the third straight line portion L163 and curving, a third corner portion C163 connecting the third straight line portion L163 and the fourth straight line portion L164 and curving, and a fourth corner portion C164 connecting the fourth straight line portion L164 and the first straight line portion L161 and curving.

[0065] The outer edge of the external electrode 127 is defined by a first straight line portion L171 extending linearly along the L axis, a second straight line portion L172 extending linearly along the W axis, a third straight line portion L173 extending linearly along the L axis, a fourth straight line portion L174 extending linearly along the W axis, a first corner portion C171 connecting the first straight line portion L171 and the second straight line portion L172 and curving, a second corner portion C172 connecting the second straight line portion L172 and the third straight line portion L173 and curving, a third corner portion C173 connecting the third straight line portion L173 and the fourth straight line portion L174 and curving, and a fourth corner portion C174 connecting the fourth straight line portion L174 and the first straight line portion L171 and curving.

[0066] The outer edge of the external electrode 128 is defined by a first straight line portion L181 extending linearly along the L axis, a second straight line portion L182 extending linearly along the W axis, a third straight line portion L183 extending linearly along the L axis, a fourth straight line portion L184 extending linearly along the W axis, a first corner portion C181 connecting the first straight line portion L181 and the second straight line portion L182 and curving, a second corner portion C182 connecting the second straight line portion L182 and the third straight line portion L183 and curving, a third corner portion C183 connecting the third straight line portion L183 and the fourth straight line portion L184 and curving, and a fourth corner portion C184 connecting the fourth straight line portion L184 and the first straight line portion L181 and curving.

[0067] The outer edge of each of the external electrodes 121 to 128 has multiple linearly extending portions, but these linearly extending portions are not directly connected to each other but are connected via curved corner portions, so that there are no corners where two straight lines intersect on the outer edge of each of the external electrodes 121 to 128.

[0068] Each of the external electrodes 121-128 has a shape that has no corners in a plan view, which makes it possible to prevent a strong electric field from being generated in a portion of the base electrode layer when a plating layer is formed on the base electrode layer to provide the external electrodes 121-128 on the base 110. Therefore, like the first external electrode 21, the top surface of each of the external electrodes 121-128, which has a shape that has no corners in a plan view, can be formed smoother than the surface of a conventional external electrode that has a shape that has corners in a plan view.

[0069] In the array-type coil component 101, the elements are arranged closely within the base 110. For this reason, it is necessary to improve the insulation between the external electrodes 121 to 128. In the embodiment shown in FIG. 8, the external electrodes 121 to 128 are arranged so that the linear portions of adjacent external electrodes face each other. For example, with regard to the arrangement of the external electrode 121 and the external electrode 122 adjacent to it in the L-axis direction, the fourth linear portion L114 of the external electrode 121 faces the second linear portion L122 of the external electrode 122 in the L-axis direction. Furthermore, with regard to the arrangement of the external electrode 121 and the external electrode 123 adjacent to it in the W-axis direction, the first linear portion L111 of the external electrode 121 faces the third linear portion L133 of the external electrode 123 in the L-axis direction. Similarly, adjacent external electrodes 121 to 128 are arranged so that the linear portions of each face the adjacent external electrode in both the L-axis direction and the W-axis direction. Therefore, the distance between adjacent external electrodes can be made larger than when adjacent external electrodes have curved surfaces that protrude toward each other, which makes it possible to prevent short circuits from occurring between the external electrodes 121 to 128.

[0070] 6a to 6f, the coil component 101 is mounted on a coil component-embedded substrate through the steps shown in Fig. 6a to 6f, similar to the coil component 1. As described above, the upper surface of each of the external electrodes 121 to 128 has a shape without corners in a plan view, and therefore diffuse reflection of a laser beam irradiated toward the external electrodes 121 to 128 to form via holes is suppressed. This makes it possible to form via holes with high precision for providing via conductors that connect each of the external electrodes 121 to 128 to wiring within the coil component-embedded substrate.

[0071] A Cu plating layer may be provided on the outermost layer of each of the external electrodes 121 to 128. By providing a Cu plating layer on the outermost layer of each of the external electrodes 121 to 128, it is possible to improve the connectivity between the external electrodes 121 to 128 and the substrate, and also to suppress deformation of the surfaces of the external electrodes 121 to 128 when the external electrodes 121 to 128 are irradiated with a laser.

[0072] 3. Variations 3-1 External electrode 31 In the above-described embodiments, the shapes of the first external electrode 21 and the second external electrode 22 are not limited to those shown in FIG. 2, and the shapes of the external electrodes 121 to 128 are not limited to those shown in FIG. 8. The first external electrode 21, the second external electrode 22, and the external electrodes 121 to 128 can have various shapes that do not have corners in a plan view. Modified examples of the shapes that the first external electrode 21, the second external electrode 22, and the external electrodes 121 to 128 can have in a plan view will be described with reference to FIG. 9. FIG. 9 shows a schematic plan view of an external electrode 31. The external electrode 31 can be used in place of at least one of the first external electrode 21, the second external electrode 22, and the external electrodes 121 to 128.

[0073] 9, the external electrode 31 has a shape without corners in plan view. Specifically, the outer edge of the external electrode 31 in plan view is defined by a first linear portion L31 extending linearly along the W axis, a second linear portion L32 extending linearly along the L axis, a third linear portion L33 extending linearly along the W axis, a fourth linear portion L34 extending linearly along the L axis, a first corner portion C31 connecting the first linear portion L31 and the second linear portion L32 and curving, a second corner portion C32 connecting the second linear portion L32 and the third linear portion L33 and curving, a third corner portion C33 connecting the third linear portion L33 and the fourth linear portion L34 and curving, and a fourth corner portion C34 connecting the fourth linear portion L34 and the first linear portion L31 and curving.

[0074] In the illustrated embodiment, the radii of curvature of the first corner portion C31 and the second corner portion C32 are smaller than the radii of curvature of the third corner portion C33 and the fourth corner portion C34, respectively.

[0075] The external electrode 31 has a base electrode layer and a plating layer covering the base electrode layer. The plating layer is formed by, for example, electrolytic plating.

[0076] As described above, the external electrode 31 has a shape without corners in a plan view, which can prevent a strong electric field from being generated in a part of the area on the base electrode layer when a plating layer is formed on the base electrode layer to provide the external electrode 31 on the base. Therefore, the upper surface 31a of the external electrode 31, which has a shape without corners in a plan view, is smoother than the surface of a conventional external electrode, which has a shape with corners in a plan view.

[0077] 3-2 External electrode 41 Next, another modified example of the external electrode will be described with reference to Fig. 10. Fig. 10 shows a schematic plan view of an external electrode 41. The external electrode 41 can be used in place of at least one of the first external electrode 21, the second external electrode 22, and the external electrodes 121-128.

[0078] As shown in Fig. 10 , the external electrode 41 has a shape without corners when viewed in a plan view. Specifically, the outer edge of the external electrode 41 has an elliptical shape when viewed in a plan view. The external electrode 41 may be arranged so that its major axis extends along the W-axis. When two external electrodes 41 are used in place of the first external electrode 21 and the second external electrode 22 in the coil device 1, the two external electrodes 41 can be arranged on the upper surface 10a of the base 10 so that the major axis of each of the two external electrodes 41 extends along the W-axis, thereby increasing the distance between the external electrodes 41 in the L-axis direction and thereby suppressing short circuits between the external electrodes 41.

[0079] The external electrode 41 has a base electrode layer and a plating layer covering the base electrode layer. The plating layer is formed by, for example, electrolytic plating.

[0080] As described above, the external electrode 41 has a shape without corners in a plan view, which can prevent a strong electric field from being generated in a part of the area on the base electrode layer when a plating layer is formed on the base electrode layer to provide the external electrode 41 on the base. Therefore, the upper surface 41a of the external electrode 41, which has a shape without corners in a plan view, is smoother than the surface of a conventional external electrode, which has a shape with corners in a plan view.

[0081] 4 Notes The dimensions, materials, and arrangements of each component described in the various embodiments above are not limited to those explicitly described in each embodiment, and each component can be modified to have any dimensions, materials, and arrangements that may fall within the scope of the present invention.

[0082] Components not explicitly described in this specification may be added to each of the above-described embodiments, and some of the components described in each embodiment may be omitted.

[0083] The designations "first," "second," "third," etc. in this specification are used to identify components and do not necessarily limit the number, order, or content thereof. Furthermore, numbers used to identify components are used in different contexts, and numbers used in one context do not necessarily indicate the same configuration in another context. Furthermore, this does not prevent a component identified by a certain number from also serving the function of a component identified by another number.

[0084] In this specification, when a certain component is referred to as "comprising" another component, it does not mean that other components are excluded, but that other components may be further included, unless it is inconsistent with the content of the present invention.

[0085] 5. Supplementary Notes The embodiments disclosed herein also include the following:

[0086] [Appendix 1] a substrate (10) having a first surface (10a); a first coil conductor (25) provided inside the base; a first external electrode (21) having a first plating layer (21B), provided at least on the first surface of the base so as to be connected to one end of the first coil conductor, and having a shape without corners when viewed from a normal direction (T) of the first surface; a second external electrode (22) having a second plating layer (22B), provided on at least the first surface of the base at a position spaced apart from the first external electrode in a first direction (L) so as to be connected to the other end of the first coil conductor, and having a shape without corners when viewed from a normal direction of the first surface; A coil component comprising: [Appendix 2] When viewed from the normal direction of the first surface, an outer edge of the first external electrode has a first linear portion (L13) extending along a second direction (W) perpendicular to the first direction, When viewed from the normal direction of the first surface, the outer edge of the second external electrode has a second linear portion (L21) that extends along the second direction and faces the first linear portion. The coil component described in [Appendix 1]. [Appendix 3] When viewed from the normal direction of the first surface, an outer edge of the first external electrode has a third linear portion (L12) extending along the first direction, The first straight portion and the third straight portion are connected by a curved corner portion (C12). A coil component described in [Appendix 1] or [Appendix 2]. [Appendix 4] The circularity of the outer edge of the first external electrode is 0.8 or more. A coil component according to any one of [Appendix 1] to [Appendix 3]. [Appendix 5] When viewed from the normal direction of the first surface, the outer edge of the first external electrode has an elliptical shape. A coil component according to any one of [Appendix 1] to [Appendix 4]. [Appendix 6] When viewed from the normal direction of the first surface, the outer edge of the first external electrode has an elliptical shape. A coil component according to any one of [Appendix 1] to [Appendix 5]. [Appendix 7] a second coil conductor provided inside the base; a third external electrode (123) having a third plating layer, provided at least on the first surface of the base (110) at a position spaced apart from the first external electrode (121) in the second direction so as to be connected to one end of the second coil conductor, and having a shape without corners when viewed from the normal direction of the first surface; a fourth external electrode (124) having a fourth plating layer, provided on at least the first surface of the base at a position spaced apart from the third external electrode in the first direction so as to be connected to the other end of the second coil conductor, and having a shape without corners when viewed from the normal direction of the first surface; Further equipped A coil component according to any one of [Appendix 1] to [Appendix 6]. [Appendix 8] When viewed from a normal direction of the first surface, an outer edge of the first external electrode has a third linear portion extending along the first direction, When viewed from the normal direction of the first surface, an outer edge of the third external electrode has a fourth linear portion that extends along the first direction and faces the third linear portion. The coil component described in [Appendix 7]. [Appendix 9] A coil component according to any one of [Appendix 1] to [Appendix 8]. [Explanation of symbols]

[0087] 1. 101 Coil parts 10 Insulators 21 1st external electrode 22 2nd external electrode 31, 41, 121~128 External electrode 25 Coil conductor 81 Coil component built-in board

Claims

1. a substrate having a first surface; a first coil conductor provided inside the base; a first external electrode having a first plating layer, provided at least on the first surface of the base so as to be connected to one end of the first coil conductor, and having a shape without corners when viewed from a normal direction of the first surface; a second external electrode having a second plating layer, provided on at least the first surface of the base at a position spaced apart from the first external electrode in a first direction so as to be connected to the other end of the first coil conductor, and having a shape without corners when viewed from a normal direction to the first surface; A coil component comprising:

2. When viewed from a normal direction of the first surface, an outer edge of the first external electrode has a first linear portion extending along a second direction perpendicular to the first direction, When viewed from the normal direction of the first surface, an outer edge of the second external electrode extends along the second direction and has a second linear portion opposite to the first linear portion. The coil component according to claim 1 .

3. When viewed from a normal direction of the first surface, an outer edge of the first external electrode has a third linear portion extending along the first direction, The first straight portion and the third straight portion are connected by a curved corner portion. The coil component according to claim 2 .

4. The circularity of the outer edge of the first external electrode is 0.8 or more. The coil component according to claim 1 or 2.

5. When viewed from a normal direction of the first surface, an outer edge of the first external electrode has an elliptical shape. The coil component according to claim 1 or 2.

6. When viewed from a normal direction of the first surface, an outer edge of the first external electrode has an elliptical shape. The coil component according to claim 1 or 2.

7. a second coil conductor provided inside the base; a third external electrode having a third plating layer, provided at least on the first surface of the base at a position spaced apart from the first external electrode in the second direction so as to be connected to one end of the second coil conductor, and having a shape without corners when viewed from a normal direction to the first surface; a fourth external electrode having a fourth plating layer, the fourth external electrode being provided on at least the first surface of the base at a position spaced apart from the third external electrode in the first direction so as to be connected to the other end of the second coil conductor, and having a shape without corners when viewed from a normal direction to the first surface; Further equipped The coil component according to claim 2 .

8. When viewed from a normal direction of the first surface, an outer edge of the first external electrode has a third linear portion extending along the first direction, When viewed from the normal direction of the first surface, an outer edge of the third external electrode has a fourth linear portion that extends along the first direction and faces the third linear portion. The coil component according to claim 7 .

9. A coil component-embedded substrate incorporating the coil component according to claim 1 or 2.

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