Coil parts

Abstract

To provide a coil component capable of suppressing the characteristic deterioration even in the case where a physical external force is applied.SOLUTION: A coil component 1 comprises: an element assembly 2 having a main surface 2a as a mounting surface; a pair of external electrodes 3 and 4 arranged on the main surface 2a; and a coil 7 that includes a screw type coil part 71 positioned in the element assembly 2, and a pair of connection parts 73 and 74 exposed from the element assembly 2 and connected to external electrodes 3 and 4 of a corresponded one of the pair of external electrodes 3 and 4. cof the pair of external electrodes 3 and 4 includes: first front faces 3a and 4a opposite to the main surface 2a; and second front faces 3b and 4b opposite to the first front faces 3a and 4a. Each of the pair of connection parts 73 and 74 includes: a first part 73a, 74a jointed to the second front face 3b, 4b of the corresponded external electrode 3, 4; and a second part 73b, 74b communicated with an end of the first part 73a, 74a and the coil part 71.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] A coil component is known that includes a substrate on which a pair of through holes are formed, a coil disposed on the substrate, and external electrodes formed on the main surface of the substrate and on the inner wall surfaces of each through hole (see, for example, Patent Document 1). In the coil component described in Patent Document 1, both ends of the coil are inserted into the corresponding through holes and joined to the external electrodes formed on the inner wall surfaces of the through holes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 56-144508 Summary of the Invention [Problem to be solved by the invention]

[0004] In the coil component described in Patent Document 1, the ends of the coil are located within the through-holes. For example, if a physical external force is applied to this coil component, the ends of the coil may easily come out of the through-holes, potentially disconnecting the electrical connection between the ends of the coil and the external electrodes. If the electrical connection between the ends of the coil and the external electrodes is disconnected, the characteristics of the coil component will deteriorate. The characteristics of the coil component include, for example, electrical characteristics or magnetic characteristics.

[0005] An object of one aspect of the present invention is to provide a coil component that suppresses deterioration of characteristics even when a physical external force is applied. [Means for solving the problem]

[0006] A coil component according to one embodiment includes an element body having a main surface that is a mounting surface, a pair of external electrodes arranged on the main surface, a coil having a spiral coil portion located within the element body, and a pair of connection portions exposed from the element body and connected to corresponding ones of the pair of external electrodes. Each of the pair of external electrodes has a first surface facing the main surface and a second surface facing the first surface. Each of the pair of connection portions has a first portion joined to the second surface of the corresponding external electrode and a second portion continuous with the first portion and an end of the coil portion.

[0007] In one aspect, each of the pair of external electrodes has a first surface facing the main surface of the element body and a second surface facing the first surface. Each of the pair of connecting portions has a first portion joined to the second surface of the corresponding external electrode. The external electrode is positioned between the element body and the first portion of the connecting portion, and the external electrode is connected to the first portion of the connecting portion. Therefore, even if a physical external force acts on the coil component, the external electrode is unlikely to come off the connecting portion, and the electrical connection between the coil and the external electrode is maintained. As a result, deterioration of the characteristics of the coil component is suppressed.

[0008] In the above-described one aspect, each of the pair of external electrodes may have a through hole that opens to the first surface and the second surface, and each of the second portions may be inserted into a corresponding through hole. In a configuration in which a pair of external electrodes each has a through hole that opens to the first surface and the second surface, and each second portion is inserted into the corresponding through hole, the first portion of the connection portion functions as an anchor that prevents the connection portion from coming off the through hole. Therefore, even if a physical external force is applied to the coil component, the external electrode is more unlikely to come off the connection portion, and the electrical connection between the coil and the external electrode is more reliably maintained. As a result, deterioration of the characteristics of the coil component is further suppressed.

[0009] In the above one aspect, the coil component may further include a plating layer formed on the second surface so as to cover the first portion. In a configuration in which the coil component has a plating layer formed on the second surface so as to cover the first portion, the first portion of the connection portion is less likely to peel off from the second surface because the plating layer covers the first portion of the connection portion. Therefore, even if a physical external force is applied to the coil component, the external electrode is less likely to come off from the connection portion, and the electrical connection between the coil and the external electrode is more reliably maintained. As a result, deterioration of the characteristics of the coil component is further suppressed.

[0010] In the above aspect, the element body may have a first element body part covering the coil portion and a second element body part including the main surface. The second element body part may be located between the coil portion and the pair of external electrodes. In a configuration in which the element body has a first element body portion and a second element body portion, and the second element body portion is located between the coil portion and a pair of external electrodes, the element body is composed of at least two portions, which increases the freedom of material selection for the element body and widens the range of adjustment for the characteristics of the coil component.

[0011] In the above one aspect, the second element body portion may be formed from a material having a lower relative dielectric constant than the first element body portion. In a configuration in which the second body portion is made of a material with a lower dielectric constant than the first body portion, the second body portion reduces the stray capacitance that occurs between the coil portion and the external electrodes, thereby suppressing a decrease in the self-resonant frequency of the coil component. [Effects of the Invention]

[0012] One aspect of the present invention provides a coil component that suppresses deterioration of characteristics even when a physical external force is applied. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing a coil component according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of an external electrode. [Figure 3] FIG. 2 is a diagram showing a cross-sectional configuration of the coil component according to the first embodiment. [Figure 4]FIG. 2 is a diagram showing the element body and the coil before external electrodes are arranged. [Figure 5] FIG. 2 is a diagram showing the element body and the coil with external electrodes arranged thereon. [Figure 6] FIG. 10 is a perspective view showing a coil component according to a modified example. [Figure 7] FIG. 10 is a perspective view showing a coil component according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same elements or elements having the same functions will be denoted by the same reference numerals, and redundant description will be omitted.

[0015] (First embodiment) The configuration of a coil component 1 according to a first embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a perspective view showing the coil component according to this embodiment. Fig. 2 is a diagram showing the configuration of external electrodes. Fig. 2 is a perspective view of the coil component shown in Fig. 1 in which plating layers 8 and 9 are omitted. Fig. 3 is a diagram showing the cross-sectional configuration of the coil component. The coil component 1 includes an element body 2, a pair of external electrodes 3 and 4, a coil 7, and plating layers 8 and 9.

[0016] The element body 2 has a rectangular parallelepiped shape. The rectangular parallelepiped shape includes a rectangular parallelepiped shape with chamfered corners and ridges, and a rectangular parallelepiped shape with rounded corners and ridges. The element body 2 has a main surface 2a, a pair of side surfaces 2b and 2c, and a pair of end surfaces 2d and 2e. The pair of side surfaces 2b and 2c face each other. The direction in which the pair of side surfaces 2b and 2c face each other is the first direction D1. The pair of end surfaces 2d and 2e face each other. The direction in which the pair of end surfaces 2d and 2e face each other is the second direction D2. The direction perpendicular to the main surface 2a is the third direction D3. In this embodiment, the first direction D1 is the short-side direction of the element body 2. The second direction D2 is the longitudinal direction of the element body 2 and is perpendicular to the first direction D1. The third direction D3 is the height direction of the element body 2 and is perpendicular to the first direction D1 and the second direction D2.

[0017] The main surface 2a extends along the first direction D1 and the second direction D2. The side surfaces 2b, 2c extend along the second direction D2 and the third direction D3. The end surfaces 2d, 2e extend along the first direction D1 and the third direction D3. The main surface 2a connects the pair of side surfaces 2b, 2c together. The main surface 2a also connects the pair of end surfaces 2d, 2e together. The coil component 1 is mounted to an electronic device, for example, by soldering. The electronic device is, for example, a circuit board or an electronic component. In the coil component 1, the main surface 2a is the mounting surface that faces the electronic device.

[0018] The element body 2 is made of, for example, an electrically insulating material. The element body 2 is made of, for example, a resin. The resin is, for example, a liquid crystal polymer (LCP), a polyimide resin, a crystalline polystyrene, an epoxy resin, or a fluororesin. The polyimide resin is, for example, a bismaleimide resin. The fluororesin is, for example, a polytetrafluoroethylene resin (PTFE). The material making up the element body 2 may contain a filler or impurities to improve the characteristics of the coil component 1.

[0019] The pair of external electrodes 3, 4 are arranged on the main surface 2a. The pair of external electrodes 3, 4 are electrically connected to the coil 7. As shown in FIG. 2, the pair of external electrodes 3, 4 are arranged at both ends of the element body 2 in the second direction D2. The pair of external electrodes 3, 4 are spaced apart from each other in the second direction D2. The external electrode 3 is arranged on the end face 2d side. The external electrode 4 is arranged on the end face 2e side.

[0020] Each of the external electrodes 3, 4 has a flat plate shape. Each of the external electrodes 3, 4 has a thickness in the third direction D3. In this embodiment, each of the external electrodes 3, 4 has a rectangular shape in plan view. Each of the external electrodes 3, 4 may have a rectangular shape with rounded corners in plan view, or may have an elliptical or oblong shape. The longitudinal direction of each of the external electrodes 3, 4 is along the first direction D1, i.e., the short-side direction of the element body 2. In this embodiment, the length of each of the external electrodes 3, 4 in the first direction D1 is equal to the length of the element body 2 in the first direction D1. Hereinafter, "equal" does not necessarily mean that the values ​​are the same. The values ​​may be considered to be equal even if they include slight differences, manufacturing errors, or measurement errors within a predetermined range.

[0021] As shown in FIG. 3 , the external electrode 3 has a first surface 3a and a second surface 3b. The first surface 3a is a flat surface extending along the first direction D1 and the second direction D2. The first surface 3a faces the principal surface 2a. The first surface 3a may face the principal surface 2a directly or indirectly. The first surface 3a facing the principal surface 2a directly means that no intervening element exists between the first surface 3a and the principal surface 2a. The first surface 3a facing the principal surface 2a indirectly means that an intervening element exists between the first surface 3a and the principal surface 2a. An adhesive may be disposed between the first surface 3a and the principal surface 2a as an intervening element.

[0022] The second surface 3b is a flat surface extending along the first direction D1 and the second direction D2. In this embodiment, the second surface 3b is parallel to the first surface 3a. The second surface 3b faces the first surface 3a. As shown in FIG. 3, the external electrode 3 has a through hole 31 formed therein that opens to the first surface 3a and the second surface 3b. When viewed from the third direction D3, the outer edge of the through hole 31 has a circular shape.

[0023] The external electrode 4 has a first surface 4a and a second surface 4b. The first surface 4a is a flat surface extending along the first direction D1 and the second direction D2. The first surface 4a faces the principal surface 2a. The first surface 4a may face the principal surface 2a directly or indirectly. The first surface 4a facing the principal surface 2a directly means that no intervening element exists between the first surface 4a and the principal surface 2a. The first surface 4a facing the principal surface 2a indirectly means that an intervening element exists between the first surface 4a and the principal surface 2a. An adhesive may be disposed between the first surface 4a and the principal surface 2a as an intervening element.

[0024] The second surface 4b is a flat surface extending along the first direction D1 and the second direction D2. In this embodiment, the second surface 4b is parallel to the first surface 4a. The second surface 4b faces the first surface 4a. The external electrode 4 is formed with a through hole 41 that opens to the first surface 4a and the second surface 4b. When viewed from the third direction D3, the outer edge of the through hole 41 has a circular shape.

[0025] Each of the external electrodes 3, 4 is made of, for example, a metal material. Examples of the metal material include copper, silver, gold, nickel, and chromium. Each of the external electrodes 3, 4 may be formed by electroplating or LDS (Laser Direct Structuring). Each of the external electrodes 3, 4 may be formed by applying an electrode paste to the element body 2 and then drying it. The electrode paste is formed on the element body 2 using, for example, a screen printing method. Each of the external electrodes 3, 4 may be formed by pressing a metal material into a flat plate shape.

[0026] The coil 7 has a coil portion 71 and a pair of connection portions 73, 74. The coil portion 71 is located within the element body 2. The coil portion 71 has a spiral shape. The axis of the coil portion 71 is along the first direction D1. The coil portion 71 has a plurality of turns aligned in the first direction D1.

[0027] The pair of connection portions 73, 74 are exposed from the element body 2. Each of the pair of connection portions 73, 74 is continuous with a corresponding one of both ends of the coil portion 71. As shown in FIG. 2 , the pair of connection portions 73, 74 are located on a diagonal line of the main surface 2a when viewed from the third direction D3. In this embodiment, the pair of connection portions 73, 74 are located on a diagonal line connecting the ridge portion of the side surface 2b and the end surface 2d with the ridge portion of the side surface 2c and the end surface 2e. The connection portion 73 is located closer to the ridge portion of the side surface 2b and the end surface 2d than the connection portion 74. Each of the pair of connection portions 73, 74 is connected to a corresponding one of the pair of external electrodes 3, 4. The connection portion 73 is electrically and physically connected to the external electrode 3. The connection portion 74 is electrically and physically connected to the external electrode 4.

[0028] The coil portion 71 and the pair of connecting portions 73, 74 are made of wire. The wire is made of, for example, a metal material. The metal material is, for example, copper, silver, gold, nickel, or chromium. The diameter of the wire is, for example, 20 μm or more and 40 μm or less. As shown in FIG. 3 , a coating 77 is formed around the wire that makes up the coil portion 71. The coating 77 is, for example, made of an electrically insulating material. The electrically insulating material is, for example, polyurethane. The coating 77 is not formed around the wire that makes up the connecting portions 73, 74.

[0029] The connection portion 73 has a first portion 73a and a second portion 73b. As shown in FIG. 3, the first portion 73a is exposed from the external electrode 3. As shown in FIG. 2, the first portion 73a has a circular shape when viewed from the third direction D3. The diameter of the first portion 73a when viewed from the third direction D3 is larger than the inner diameter of the through hole 31. The shape of the first portion 73a is not limited, and the first portion 73a may have a rectangular or elliptical shape when viewed from the third direction D3. The first portion 73a is bonded to the second surface 3b. The first portion 73a may be fused to the second surface 3b without an intervening element. For example, the first portion 73a may be fused to the second surface 3b by thermocompression bonding or ultrasonic bonding. The first portion 73a may be bonded to the second surface 3b via an intervening element (e.g., an adhesive).

[0030] The second portion 73b connects the first portion 73a to a corresponding one of both ends of the coil portion 71. The second portion 73b extends in the third direction D3. One end of the second portion 73b is continuous with the first portion 73a. The other end of the second portion 73b is continuous with an end of the coil portion 71. The second portion 73b is inserted into the through hole 31. The cross-sectional shape of the second portion 73b is circular. The diameter of the second portion 73b is smaller than the inner diameter of the through hole 31. A gap is formed between the side surface of the second portion 73b and the inner surface of the through hole 31. The diameter of the cross-section of the second portion 73b may be equal to the inner diameter of the through hole 31. The side surface of the second portion 73b may be in contact with the inner surface of the through hole 31.

[0031] The connection portion 74 has a first portion 74a and a second portion 74b. The first portion 74a is exposed from the external electrode 4. As shown in FIG. 2, the first portion 74a has a circular shape when viewed from the third direction D3. The diameter of the first portion 74a when viewed from the third direction D3 is larger than the inner diameter of the through hole 41. The shape of the first portion 74a is not limited, and the first portion 74a may have a rectangular or elliptical shape when viewed from the third direction D3. The first portion 74a is bonded to the second surface 4b. The first portion 74a may be fused to the second surface 4b without an intervening element. For example, the first portion 74a may be fused to the second surface 4b by thermocompression bonding or ultrasonic bonding. The first portion 74a may be bonded to the second surface 4b via an intervening element (e.g., an adhesive).

[0032] The second portion 74b connects the first portion 74a to a corresponding one of both ends of the coil portion 71. The second portion 74b extends in the third direction D3. One end of the second portion 74b is continuous with the first portion 74a. The other end of the second portion 74b is continuous with an end of the coil portion 71. The second portion 74b is inserted into the through hole 41. The cross-sectional shape of the second portion 74b is circular. The diameter of the second portion 74b is smaller than the inner diameter of the through hole 41. A gap is formed between the side surface of the second portion 74b and the inner surface of the through hole 41. The diameter of the cross-section of the second portion 74b may be equal to the inner diameter of the through hole 41. The side surface of the second portion 74b may be in contact with the inner surface of the through hole 41.

[0033] The plating layer 8 is formed on the second surface 3b so as to cover the first portion 73a. A portion of the first portion 73a is located so as to be sandwiched between the plating layer 8 and the second surface 3b. In this embodiment, the plating layer 8 is formed over the entire second surface 3b. The plating layer 9 is formed on the second surface 4b so as to cover the first portion 74a. A portion of the first portion 74a is located so as to be sandwiched between the plating layer 9 and the first surface 4a. In this embodiment, the plating layer 9 is formed over the entire second surface 4b. Each of the plating layers 8, 9 is made of, for example, a metal material. The metal material is, for example, copper, silver, gold, nickel, or chromium. Each of the plating layers 8, 9 may be formed by electroplating or LDS.

[0034] The state of the coil 7 during the manufacturing process of the coil device 1 will be described with reference to Figures 4 and 5. Figure 4 is a diagram showing the element body 2 and the coil 7 before the external electrodes 3, 4 are arranged. Figure 5 is a diagram showing the element body 2 and the coil 7 in a state in which the external electrodes 3, 4 are arranged. Both Figures 4 and 5 show the state before the connecting portions 73, 74 are joined to the external electrodes 3, 4. The manufacturing process of the coil device 1 includes the steps shown in Figure 4 and the steps shown in Figure 5.

[0035] As shown in FIG. 4, when the connection portion 73 is not joined to the external electrode 3, the connection portion 73 does not have a first portion 73a or a second portion 73b. In the state shown in FIG. 4, the connection portion 73 is cylindrical, and the central axis of the connection portion 73 extends along the third direction D3. Similarly, when the connection portion 74 is not joined to the external electrode 4, the connection portion 74 does not have a first portion 74a or a second portion 74b. In the state shown in FIG. 4, the connection portion 74 is cylindrical, and the central axis of the connection portion 74 extends along the third direction D3. The diameter of each of the connection portions 73, 74 is constant in the third direction D3.

[0036] In the state shown in FIG. 5, the external electrodes 3 and 4 are disposed on the main surface 2a. The connection portion 73 is inserted into the through hole 31, and the connection portion 74 is inserted into the through hole 41. The length of each of the connection portions 73 and 74 in the third direction D3 is greater than the thickness of each of the external electrodes 3 and 4. An end of the connection portion 73 is exposed to the outside of the external electrode 3 through the through hole 31. Similarly, an end of the connection portion 74 is exposed to the outside of the external electrode 4 through the through hole 41. In this embodiment, the end of the connection portion 73 exposed from the through hole 31 is fused to the second surface 3b. The state after fusion is the state shown in FIG. 2. The end of the connection portion 73 exposed from the through hole 31 (the fused portion) shown in FIG. 5 constitutes the first portion 73a shown in FIG. 2. The portion of the connection portion 73 shown in FIG. 5 located inside the through hole 31 constitutes the second portion 73b shown in FIG. 2. Similarly, the end of the connection portion 74 exposed from the through hole 41 (the portion to be fused) constitutes the first portion 74a shown in Fig. 2. The portion of the connection portion 74 shown in Fig. 5 that is located inside the through hole 41 constitutes the second portion 74b shown in Fig. 2.

[0037] In the coil component 1 according to this embodiment, each of the pair of external electrodes 3 and 4 has a first surface 3a, 4a facing the main surface 2a of the element body 2 and a second surface 3b, 4b facing the first surface 3a, 4a. Each of the pair of connection portions 73, 74 has a first portion 73a, 74a joined to the second surface 3b, 4b of the corresponding external electrode 3, 4. The external electrodes 3 and 4 are located between the element body 2 and the first portions 73a, 74a of the connection portions 73, 74, and are connected to the first portions 73a, 74a of the connection portions 73, 74. Therefore, even if a physical external force acts on the coil component 1, the external electrodes 3 and 4 are unlikely to come off the connection portions 73 and 74, and the electrical connection between the coil 7 and the external electrodes 3 and 4 is maintained. As a result, deterioration of the characteristics of the coil component 1 is suppressed.

[0038] Through holes 31, 41 that open to the first surfaces 3a, 4a and the second surfaces 3b, 4b are formed in each of the pair of external electrodes 3, 4. The second portions 73b, 74b are inserted into the corresponding through holes 31, 41, respectively. In a configuration in which through holes 31, 41 that open to the first surfaces 3a, 4a and the second surfaces 3b, 4b are formed in each of the pair of external electrodes 3, 4, and the second portions 73b, 74b are inserted into the corresponding through holes 31, 41, respectively, the first portions 73a, 74a of the connection portions 73, 74 function as anchors that prevent the connection portions 73, 74 from coming off the through holes 31, 41. Therefore, even if a physical external force is applied to the coil component 1, the external electrodes 3, 4 are more unlikely to come off the connection portions 73, 74, and the electrical connection between the coil 7 and the external electrodes 3, 4 is more reliably maintained. As a result, deterioration of the characteristics of the coil component 1 is further suppressed.

[0039] In the one embodiment, the coil device 1 includes plating layers 8 and 9 formed on the second surfaces 3b and 4b so as to cover the first portions 73a and 74a. In a configuration in which the coil component 1 includes plating layers 8, 9 formed on the second surfaces 3b, 4b so as to cover the first portions 73a, 74a, the first portions 73a, 74a of the connection portions 73, 74 are covered by the plating layers 8, 9, making the first portions 73a, 74a less likely to peel off from the second surfaces 3b, 4b. Therefore, even when a physical external force is applied to the coil component 1, the external electrodes 3, 4 are less likely to come off the connection portions 73, 74, and the electrical connection between the coil 7 and the external electrodes 3, 4 is more reliably maintained. As a result, deterioration of the characteristics of the coil component 1 is further suppressed.

[0040] (Variation) The configuration of one modified example of the coil device 1 will be described with reference to Fig. 6. Fig. 6 is a perspective view showing a coil device 1A according to the modified example. This modified example differs from the first embodiment described above in terms of the configuration of the element body. Below, differences between the first embodiment described above and this modified example will be mainly described, and descriptions of common points may be omitted.

[0041] The element body 2A according to the modified example has a first element body portion 21 and a second element body portion 22. The first element body portion 21 covers the coil portion 71. The first element body portion 21 has a rectangular parallelepiped shape. The first element body portion 21 includes a main surface 21a, a pair of side surfaces 21b and 21c, and a pair of end surfaces 21d and 21e. The pair of side surfaces 21b and 21c face each other in the first direction D1. The pair of end surfaces 21d and 21e face each other in the second direction D2.

[0042] The main surface 21a extends along the first direction D1 and the second direction D2. The side surfaces 21b, 21c extend along the second direction D2 and the third direction D3. The end surfaces 21d, 21e extend along the first direction D1 and the third direction D3. The main surface 21a connects the pair of side surfaces 21b, 21c. The main surface 21a also connects the pair of end surfaces 21d, 21e. The main surface 21a is in direct contact with the second element body portion 22.

[0043] The second element body portion 22 has a rectangular parallelepiped shape. The second element body portion 22 is located between the coil portion 71 and the pair of external electrodes 3, 4. The second element body portion 22 may constitute a substrate of the coil device 1A. The second element body portion 22 includes a main surface 22a, a pair of side surfaces 22b, 22c, and a pair of end surfaces 22d, 22e. The pair of side surfaces 22b, 22c face each other in the first direction D1. The pair of end surfaces 22d, 22e face each other in the second direction D2.

[0044] The main surface 22a extends along the first direction D1 and the second direction D2. The side surfaces 22b, 22c extend along the second direction D2 and the third direction D3. The end surfaces 22d, 22e extend along the first direction D1 and the third direction D3. The main surface 22a connects the pair of side surfaces 22b, 22c. The main surface 22a also connects the pair of end surfaces 22d, 22e. The main surface 22a constitutes the main surface 2a, which is the mounting surface of the coil component 1A. That is, the second body portion 22 includes the main surface 2a.

[0045] The side surface 21b is flush with the side surface 22b and constitutes the side surface 2b together with the side surface 22b. The side surface 21c is flush with the side surface 22c and constitutes the side surface 2c together with the side surface 22c. The end surface 21d is flush with the end surface 22d and constitutes the end surface 2d together with the end surface 22d. The end surface 21e is flush with the end surface 22e and constitutes the end surface 2e together with the end surface 22e.

[0046] The first element portion 21 and the second element portion 22 are each made of, for example, an electrically insulating material. The first element portion 21 and the second element portion 22 are each made of, for example, a resin. The resin is, for example, a liquid crystal polymer (LCP), a polyimide resin, a crystalline polystyrene, an epoxy resin, or a fluororesin. The polyimide resin is, for example, a bismaleimide resin. The fluororesin is, for example, a polytetrafluoroethylene resin (PTFE). The material making up the first element portion 21 and the second element portion 22 may contain a filler or impurities to improve the characteristics of the coil device 1A. The second element portion 22 may be made of a material having a lower dielectric constant than the first element portion 21. The dielectric constant of the material making up the first element portion 21 is, for example, not less than 2 and not more than 4. The dielectric constant of the material making up the second element portion 22 is, for example, not less than 2 and not more than 3.

[0047] In this modification, the element body 2A has a first element body portion 21 that covers the coil portion 71, and a second element body portion 22 that includes the main surface 2a. The second element body portion 22 is located between the coil portion 71 and the pair of external electrodes 3, 4. In a configuration in which the element body 2A has a first element body portion 21 and a second element body portion 22, and the second element body portion 22 is located between the coil portion 71 and a pair of external electrodes 3, 4, the element body 2A is composed of at least two portions, which increases the freedom of material selection for the element body 2A and widens the range of adjustment for the characteristics of the coil component 1A.

[0048] In this modification, the second element body portion 22 may be made of a material having a lower relative dielectric constant than the first element body portion 21 . In a configuration in which the second element body portion 22 is made of a material having a lower dielectric constant than that of the first element body portion 21, the stray capacitance generated between the coil portion 71 and the external electrodes 3, 4 is reduced by the second element body portion 22. As a result, a decrease in the self-resonant frequency of the coil device 1A is suppressed.

[0049] Second Embodiment A coil component 1B according to the second embodiment will be described with reference to FIG. 7. FIG. 7 is a perspective view showing the coil component 1B according to the second embodiment. The second embodiment differs from the first embodiment described above in terms of the configurations of the external electrodes 3B, 4B and the connecting portions 173, 174. Below, differences between the first and second embodiments described above will be mainly described, and common points may not be described. The coil component 1B according to the second embodiment includes an element body 2, a pair of external electrodes 3B, 4B, and a coil 7B. The configuration of the element body 2 is the same as that described in the first embodiment.

[0050] In the coil device 1, as shown in FIG. 2, the length of each of the external electrodes 3, 4 in the first direction D1 is equal to the length of the element body 2 in the first direction D1. In contrast, in the coil device 1B, the length of each of the external electrodes 3B, 4B in the first direction D1 is shorter than the length of the element body 2 in the first direction D1. In this embodiment, the length of each of the external electrodes 3B, 4B in the first direction D1 is approximately half the length of the element body 2 in the first direction D1. In this embodiment, each of the external electrodes 3B, 4B has a square shape in a plan view. Each of the external electrodes 3B, 4B may have a square shape with rounded corners in a plan view, or may have an elliptical or circular shape.

[0051] The external electrode 3B has a first surface 13a and a second surface 13b. The first surface 13a faces the main surface 2a. The first surface 13a may face the main surface 2a directly or indirectly. The second surface 13b faces the first surface 13a. The external electrode 3B is positioned so as to be sandwiched between the element body 2 and a first portion 173a of the connecting portion 173. In the coil device 1, as shown in FIG. 2, a through hole 31 is formed in the external electrode 3. In contrast, in the coil device 1B, no through hole is formed in the external electrode 3B.

[0052] The external electrode 4B has a first surface 14a and a second surface 14b. The first surface 14a faces the main surface 2a. The first surface 14a may face the main surface 2a directly or indirectly. The second surface 14b faces the first surface 14a. The external electrode 4B is positioned so as to be sandwiched between the element body 2 and a first portion 174a of the connecting portion 174. In the coil device 1, as shown in FIG. 2, a through hole 41 is formed in the external electrode 4. In contrast, in the coil device 1B, no through hole is formed in the external electrode 4B.

[0053] The coil 7 has a coil portion 71 and a pair of connecting portions 173, 174. The configuration of the coil portion 71 is the same as the configuration described in the first embodiment. Each of the pair of connecting portions 173, 174 is continuous with a corresponding one of both ends of the coil portion 71. The connecting portion 173 is located closer to the end face 2d than the center of the main surface 2a. The connecting portion 174 is located closer to the end face 2e than the center of the main surface 2a.

[0054] The connecting portion 173 has a first portion 173a and a second portion 173b. In the coil device 1, the first portion 173a has a circular shape when viewed from the third direction D3. In contrast, in the coil device 1B, the first portion 173a has a rectangular shape with rounded corners when viewed from the third direction D3. The shape of the first portion 173a is not limited, and the first portion 173a may have an elliptical or circular shape when viewed from the third direction D3. The first portion 173a is joined to the second surface 13b. The joining method is not limited, and may be the same as the method for joining the first portion 73a to the second surface 13b described in the first embodiment.

[0055] The second portion 173b connects the first portion 173a to a corresponding one of both ends of the coil portion 71. One end of the second portion 173b is continuous with the first portion 173a. The other end of the second portion 173b is continuous with an end of the coil portion 71. In the coil device 1, the entire second portion 73b extends in the third direction D3. In contrast, in the coil device 1B, the second portion 173b extends not only in the third direction D3 but also in the first direction D1.

[0056] Specifically, the second portion 173b has a bent portion M1 and a straight portion M2. The bent portion M1 is located at the other end of the second portion 173b and is continuous with the end of the coil portion 71. The bent portion M1 is bent from the third direction D3 to the first direction D1. The straight portion M2 is the portion of the second portion 173b other than the bent portion M1 and extends along the first direction D1. The portion of the second portion 173b that is continuous with the end of the coil portion 71 (in this embodiment, the bent portion M1) is located outside the outer edge of the external electrode 3B when viewed from the third direction D3.

[0057] The first portion 173a and the second portion 173b are formed, for example, by the following method. First, a portion of the wire constituting the coil 7B that is exposed from the main surface 2a of the element body 2 (hereinafter referred to as the exposed portion) is bent and arranged so as to extend along the first direction D1. The bent portion corresponds to the bent portion M1. The exposed portion is arranged so that a portion of the exposed portion overlaps with the external electrode 3B in the third direction D3. Next, the portion of the exposed portion that overlaps with the external electrode 3B is joined to the second surface 13b. In this embodiment, the portion that overlaps with the external electrode 3B is melted and fused to the second surface 13b. Of the exposed portion, the portion joined to the second surface 3b corresponds to the first portion 173a, and the other portion corresponds to the second portion 173b.

[0058] Like the connecting portion 173, the connecting portion 174 has a first portion 174a and a second portion 174b. The first portion 174a has a rectangular shape with rounded corners when viewed from the third direction D3. The shape of the first portion 174a is not limited, and the first portion 174a may have an elliptical or circular shape when viewed from the third direction D3. The first portion 174a is joined to the second surface 14b. The joining method is not limited, and may be the same as the joining method of the first portion 174a and the second surface 14b described in the first embodiment.

[0059] The second portion 174b connects the first portion 174a to a corresponding one of the ends of the coil portion 71. One end of the second portion 174b is continuous with the first portion 174a. The other end of the second portion 174b is continuous with the end of the coil portion 71. The second portion 174b has a bent portion M3 and a straight portion M4. The bent portion M3 is located at the other end of the second portion 174b and is continuous with the end of the coil portion 71. The bent portion M3 is bent from the third direction D3 to the first direction D1. The straight portion M4 is the portion of the second portion 174b other than the bent portion M3 and extends along the first direction D1. The portion of the second portion 174b that is continuous with the end of the coil portion 71 (in this embodiment, the bent portion M3) is located outside the outer edge of the external electrode 4B when viewed from the third direction D3. The method for forming the first portion 174a and the second portion 174b is similar to the method for forming the first portion 173a and the second portion 173b.

[0060] In the second embodiment, as in the first embodiment described above, each of the pair of external electrodes 3B, 4B has a first surface 13a, 14a facing the main surface 2a of the element body 2 and a second surface 13b, 14b facing the first surface 13a, 14a. Each of the pair of connecting portions 173, 174 has a first portion 173a, 174a joined to the second surface 13b, 14b of the corresponding external electrode 3B, 4B. The external electrodes 3B, 4B are located between the element body 2 and the first portions 173a, 174a of the connecting portions 173, 174, and the external electrodes 3B, 4B are connected to the first portions 173a, 174a of the connecting portions 173, 174. Therefore, even if a physical external force acts on the coil device 1B, the external electrodes 3B, 4B are unlikely to come off the connecting portions 173, 174, and electrical connection between the coil 7B and the external electrodes 3B, 4B is maintained. As a result, deterioration of the characteristics of the coil component 1B is suppressed.

[0061] The above describes embodiments and modifications of the present invention, but the present invention is not necessarily limited to the above-described embodiments and modifications, and various modifications are possible without departing from the spirit of the present invention.

[0062] In the first embodiment, the plating layer 8 need only cover at least the first portion 73a and need not be formed over the entire second surface 3b. Similarly, the plating layer 9 need only cover at least the first portion 74a and need not be formed over the entire second surface 4b.

[0063] In the second embodiment, the length of each of the external electrodes 3B, 4B in the first direction D1 may be equal to the length of the element body 2 in the first direction D1. That is, in the coil component 1B according to the second embodiment, the external electrodes 3B, 4B may have the same configuration as the external electrodes 3, 4 according to the first embodiment. Specifically, the external electrode 3B may have a through hole that opens to the first surface 13a and the second surface 13b, and the bent portion M1 of the second portion 173b may be inserted into the through hole. Similarly, the external electrode 4B may have a through hole that opens to the first surface 14a and the second surface 14b, and the bent portion M3 of the second portion 174b may be inserted into the through hole.

[0064] In the second embodiment, the coil device 1B may further include a plating layer formed on the second surface 13b so as to cover the first portion 173a, and a plating layer formed on the second surface 14b so as to cover the first portion 174a. [Explanation of symbols]

[0065] 1,1A,1B...Coil parts, 2,2A...Element body, 2a...Main surface, 3,3B,4,4B...External electrode, 3a,4a,13a,14a...First surface, 3b,4b,13b,14b...Second surface, 7,7B...Coil, 8,9...Plating layer, 21 ...first element body part, 22...second element body part, 31,41...through hole, 71...coil part, 73,74,173,174...connection part, 73a,74a,173a,174a...first part, 73b,74b,173b,174b...second part.

Claims

1. an element body having a main surface that is a mounting surface; a pair of external electrodes disposed on the main surface; a coil having a spiral coil portion located within the element body and a pair of connection portions exposed from the element body and connected to corresponding ones of the pair of external electrodes, each of the pair of external electrodes has a first surface facing the main surface and a second surface facing the first surface; each of the pair of connection portions has a first portion joined to the second surface of the corresponding external electrode and a second portion continuous with the first portion and an end of the coil portion; At least a portion of the first portion is disposed on the second surface; a through hole opening to the first surface and the second surface is formed in each of the pair of external electrodes; Each of the second portions is inserted into a corresponding one of the through holes.

2. The coil component according to claim 1 , further comprising a plating layer formed on the second surface so as to cover the first portion.

3. the element body has a first element body portion covering the coil portion and a second element body portion including the main surface, The coil component according to claim 1 , wherein the second body portion is located between the coil portion and the pair of external electrodes.

4. The coil component according to claim 3 , wherein the second element portion is formed from a material having a lower dielectric constant than the first element portion.

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