Coil component

Abstract

This invention provides a coil component with a structure that prevents unintentional cutting of the wire and enables stable and adequate heat bonding. Terminal electrodes (25, 26) are provided on the mounting surfaces (21, 22) of the flange portion (13, 14) of the drum-shaped core (15) facing the mounting substrate, and recesses (27, 28) open on the inner end face (17, 18) side and flat surfaces (29, 30) excluding the recesses are provided. A convex arc surface (31, 32) is formed on the bottom surface of the recess, having a height difference relative to the flat surface that is less than or equal to the diameter of the wire (23). The end of the wire (23) connected to the terminal electrode extends along the arc surface (31, 32) from the inner end face side toward the outer end face (19, 20), resulting in a continuous change in thickness, being thinner on the outer end face side and thicker on the inner end face side.

Description

[0001] This application is a divisional application of patent application No. 201911308152.7, filed on December 18, 2019, filed by Murata Manufacturing Co., Ltd., entitled "Coil Component". Technical Field

[0002] The present invention relates to a wound coil component with a structure in which a wire is wound around a drum-shaped core, and particularly to the structure of the connection portion between the wire and the terminal electrode. Background Technology

[0003] For example, Japanese Patent Application Publication No. 2006-286807 (Patent Document 1) or Japanese Patent Application Publication No. 2011-216681 (Patent Document 2) disclose a wound coil component in which the end of a wire is connected to terminal electrodes respectively provided on the flange portions located at both ends of a drum-shaped core by heat pressing.

[0004] Figure 8 A partial enlarged cross-sectional view of the flange portion 2 located at one end of the drum-shaped core 1 is shown. Figure 8 The flange portion 2 shown illustrates the mounting surface 3 facing the mounting substrate during installation, and a terminal electrode 4 is provided on the mounting surface 3. The terminal electrode 4 comprises: a conductive film formed by firing a conductive paste, for example, with silver as a conductive component, and a plating film such as Ni, Cu, or Sn formed on the conductive film. Furthermore, to achieve good solderability during installation, the surface of the terminal electrode 4 is formed with a Sn plating film.

[0005] On the other hand, the end of the wire 6, which is spirally wound around the core portion 5 of the drum-shaped core 1, is connected to the terminal electrode 4 described above by heat pressing. The wire 6 is, for example, made of copper wire, and its periphery is covered by an insulating film made of resin such as polyurethane or polyimide. The insulating film made of resin is decomposed and removed by heat, for example, during heat pressing.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2006-286807

[0007] Patent Document 2: Japanese Patent Application Publication No. 2011-216681

[0008] To fully and properly realize the 6-directional properties of the wire Figure 8 The hot-pressing of the terminal electrode 4 as shown requires applying a relatively high temperature, such as 300 to 500°C, and a relatively high pressure to the wire 6 to cause the wire 6 to undergo appropriate plastic deformation.

[0009] However, the inventors of this case discovered that, as a result of the pressure applied during the aforementioned hot-pressing process, stress concentration occurs in the portion 8 of the wire 6 near the ridge line where the mounting surface 3 of the flange 2 intersects with the inner end face 7, and sometimes the wire is prone to breakage at this portion 8. Specifically, it is known that, for example, when the diameter of the wire 6 is reduced to 15–100 μm due to miniaturization of the coil component, the aforementioned wire breakage may occur when the coil component is exposed to a high temperature of 120–150°C. Summary of the Invention

[0010] Therefore, the object of the present invention is to provide a coil component having a structure that can simultaneously prevent wire breakage and stabilize the heat-pressed connection.

[0011] Both the first and second aspects of the present invention relate to a coil component, which includes: a drum-shaped core having a core portion and a flange portion provided at an end of the core portion; a wire wound around the core portion; and a terminal electrode for connecting the end of the wire.

[0012] The flange portion has: an inner end face facing the core portion and positioning the end of the core portion; an outer end face facing the outer side opposite to the inner end face; and a mounting surface connecting the inner end face and the outer end face, wherein the mounting surface faces the mounting substrate during installation. Additionally, terminal electrodes are provided on the mounting surface of the flange portion.

[0013] In a coil component having the structure described above, in order to solve the aforementioned technical problem according to the first aspect of the present invention, the characteristic is that an arc surface is formed on the mounting surface, the arc surface having a central axis along a line extending in the width direction parallel to the mounting surface and the outer end face and having a radius of curvature larger than the distance between the inner end face and the outer end face, and the end of the wire extending from the inner end face side toward the outer end face side along the arc surface.

[0014] Regarding the second aspect of the present invention, in addition to the structure common to the first and second aspects described above, in order to solve the aforementioned technical problem, it is characterized in that a recess open on the inner end face side and a flat surface other than the recess are provided on the mounting surface, the end of the wire is received in the recess from the inner end face side toward the outer end face side, and the thickness continuously changes to be thinner on the outer end face side and thicker on the inner end face side.

[0015] According to the coil component of the present invention, it is possible to simultaneously prevent wire breakage and stabilize the heat-pressed connection. Attached Figure Description

[0016] Figure 1 This is a perspective view showing the appearance of the coil component 11 according to the first embodiment of the present invention with the surface facing the mounting substrate facing upwards.

[0017] Figure 2 It is shown with the surface facing the mounting substrate facing upwards. Figure 1 A perspective view of the appearance of the drum-shaped core 15 of the coil component 11 shown.

[0018] Figure 3 It is Figure 2 A partially enlarged cross-sectional view of the drum-shaped core 15 shown.

[0019] Figure 4 It is used to explain the hot pressing process, and will Figure 1 The cross-sectional view shown is an enlarged view of each part of the drum-shaped core 15 and the wire 23 of the coil component 11 shown.

[0020] Figure 5 This is a partial enlargement of the drum-shaped core 15a and the wire 23 included in the coil component of the second embodiment of the present invention. Figure 4 The corresponding diagram.

[0021] Figure 6 This is a partial enlargement of the drum-shaped core 15b included in the coil component of the third embodiment of the present invention. Figure 3 The corresponding diagram.

[0022] Figure 7 This is a partial enlargement of the drum-shaped core 15c included in the coil component of the fourth embodiment of the present invention. Figure 3 The corresponding diagram.

[0023] Figure 8 This is a cross-sectional view showing a partial enlargement of the drum-shaped core 1 and the wire 6, which are present in conventional coil components.

[0024] Explanation of reference numerals in the attached figures

[0025] 11...coil component; 12...core portion; 13...first flange portion; 14...second flange portion; 15, 15a, 15b...drum-shaped core; 17, 18...inner end face; 19, 20...outer end face; 21, 22...mounting surface; 23...wire; 25, 26...terminal electrode; 27, 28...recess; 29, 30...flat surface; 31, 32...arc surface; 33...thermal joint; 35...area with no plastic deformation; 36...area with continuously varying thickness; 38...edge; CA...central axis; r...radius of curvature; D...step. Detailed Implementation

[0026] Figure 1 The appearance of the coil component 11 according to the first embodiment of the present invention is shown. Figure 1The coil component 11 shown has its side facing the mounting substrate facing upwards.

[0027] Reference Figure 1 The coil component 11 includes a drum-shaped core 15, which has a core portion 12 and a first flange portion 13 and a second flange portion 14 respectively provided at a first end and a second end of the core portion 12. The drum-shaped core 15 is made of, for example, alumina or ferrite. In addition, the drum-shaped core 15 has a longitudinal dimension of, for example, about 0.4 to 4.5 mm. Figure 2 The drum-shaped core 15 is shown separately.

[0028] Reference Figure 1 and Figure 2 The first flange portion 13 and the second flange portion 14 each have: inner end faces 17 and 18 facing the core portion 12 and positioning the first end and the second end of the core portion 12 respectively; outer end faces 19 and 20 facing the outer side opposite to the inner end faces 17 and 18 respectively; and mounting surfaces 21 and 22 connecting the inner end faces 17 and 18 to the outer end faces 19 and 20 respectively, and the mounting surfaces 21 and 22 facing the mounting substrate side during installation.

[0029] The coil component 11 further includes: a wire 23 wound around the core portion 12 of the drum-shaped core 15; and a first terminal electrode 25 and a second terminal electrode 26, which are respectively connected to the first end and the second end of the wire 23. The forming areas of the terminal electrodes 25 and 26 are shown by shading. The terminal electrodes 25 and 26 are respectively configured to cover the entire mounting surfaces 21 and 22 of the first flange portion 13 and the second flange portion 14.

[0030] Terminal electrodes 25 and 26 are formed by applying a conductive paste, for example, containing Ag as a conductive component and glass frit as a bonding component in a resin binder, to mounting surfaces 21 and 22 via an impregnation method, followed by firing to form a conductive film serving as a substrate. Next, Ni, Cu, Sn, or similar materials are plated onto the conductive film of the substrate. As a result of the impregnation method, terminal electrodes 25 and 26 are formed extending from mounting surfaces 21 and 22 to portions of the surfaces adjacent to mounting surfaces 21 and 22. Furthermore, to achieve good solderability during installation, it is preferable that the surfaces of terminal electrodes 25 and 26 are formed with a Sn-plated film. Alternatively, the plating film may be formed only around the connection portion of terminal electrodes 25 and 26 where they connect to wire 23.

[0031] The aforementioned wire 23 has a structure consisting of a core wire made of Cu with a diameter of approximately 15 to 200 μm, and the core wire is surrounded by an insulating film of approximately several μm thickness made of resin such as polyurethane or polyimide. The connection between each end of the wire 23 and the terminal electrodes 25 and 26 is achieved by thermoforming. The insulating film at the ends of the wire 23 is removed, for example, by thermal decomposition during thermoforming, or by laser irradiation.

[0032] The mounting surfaces 21 and 22 of the first flange portion 13 and the second flange portion 14 are given the features described below. Furthermore, such features are not given solely by tumbling or grinding, but are ultimately obtained as a result of being given during the forming stage of the drum-shaped core 15, and are thus clearly retained after post-processing such as firing and tumbling of the drum-shaped core.

[0033] The following explains the reasons why the inventors of this invention adopted the characteristic structure of the embodiments of the present invention.

[0034] Referring to the above Figure 8 The inventors of this case speculate that the copper in the central conductor of the hot-pressed wire 6 becomes brittle under harsh temperature conditions, forming an alloy between itself and the tin on the surface of the terminal electrode 4, as well as the tin contained in the solder during installation. As a result, the wire 6 is prone to breakage, especially in the portion 8 near the edge where stress tends to concentrate. Furthermore, the inventors of this case have also found that, in terms of the wire 6 being cut by this process, there is a tendency that the thicker the wire 6, the more likely it is to break.

[0035] Furthermore, the drum-shaped core 1 is made of materials such as alumina or ferrite, but after forming and firing, it undergoes tumbling. During this tumbling process, the ridge portion between the mounting surface 3 and the inner end face 7 at the flange 2, and the ridge portion between the mounting surface 3 and the outer end face 9, are rounded. Moreover, regarding the rounded chamfer state, in... Figure 8 (Not illustrated in the diagram). It's easy to imagine that, in terms of the degree of rounded chamfering, the ridge line between mounting surface 3 and inner end face 7 is relatively lower than that between mounting surface 3 and outer end face 9. This is because, in terms of the probability of collision with granular abrasive material, the ridge line between mounting surface 3 and inner end face 7 is relatively lower. Therefore, compared to the ridge line between mounting surface 3 and outer end face 9, the ridge line between mounting surface 3 and inner end face 7 retains more sharpness and has a smaller radius of curvature. This is presumably one reason why the wire 6 is prone to breakage near the ridge line at the portion 8.

[0036] To mitigate the aforementioned wire breakage, reducing the pressure applied during heat pressing could be considered to decrease the degree of plastic deformation experienced by wire 6. However, from the perspective of the adhesion strength between wire 6 and terminal electrode 4, sufficient pressure and temperature are necessary together during heat pressing; simply reducing the pressure is insufficient to achieve adequate and proper heat pressing. In any case, adjusting the pressure applied during heat pressing is crucial, but it is also extremely delicate, and undeniably, setting an appropriate pressure stably is not easy.

[0037] Given the aforementioned circumstances, it is understood that the embodiments of the present invention preferably possess the following features.

[0038] Mounting surfaces 21 and 22 are respectively provided with recesses 27 and 28 open on their inner end faces 17 and 18, and flat surfaces 29 and 30 are provided in the areas excluding the recesses 27 and 28. The recesses 27 and 28 extend from the inner end faces 17 and 18 toward the outer end faces 19 and 20. Figure 3 As clearly shown, at least partially on the bottom surfaces of each of the recesses 27 and 28, arcuate surfaces 31 and 32 are formed for recess 27. In the illustrated embodiment, the bottom surfaces of each of the recesses 27 and 28 are entirely formed by arcuate surfaces 31 and 32.

[0039] Furthermore, terminal electrodes 25 and 26 are formed covering the entire surfaces of mounting surfaces 21 and 22, respectively. Thus, the recesses 27 and 28, the flat surfaces 29 and 30, and the curved surfaces 31 and 32 described above are provided by mounting surfaces 21 and 22. However, hereafter, it will sometimes be described as the recesses 27 and 28, the flat surfaces 29 and 30, and the curved surfaces 31 and 32 being provided by terminal electrodes 25 and 26.

[0040] The following is about Figure 3 and Figure 4 The structure of the first flange portion 13 shown in the figure will be described. The structure of the second flange portion 14 is symmetrical to the structure of the first flange portion 13, so the description is omitted.

[0041] like Figure 3 As shown, the arc surface 31 of the bottom surface of the recess 27 formed on the mounting surface 21 of the first flange 13 has a central axis CA along a line extending in the width direction parallel to the mounting surface 21 and the outer end face 19, and has a radius of curvature r larger than the distance between the inner end face 17 and the outer end face 19, i.e., the thickness of the first flange 13. Furthermore, the radius of curvature r can also be infinitely large. The central axis CA may not necessarily be parallel to the ridge line L, but it is preferable to extend parallel to or almost parallel to the ridge line L. Additionally, as from... Figure 3By analogy, the central axis CA is preferably located on the surface extending from the outer end face 19, or at a position further outward than the surface extending from the outer end face 19. With this configuration, the arc surface 31 can be... Figure 3 The highest point is positioned at the edge L. This is in reference... Figure 4 It is more effective in the hot pressing process described later.

[0042] Furthermore, as a result of the aforementioned formation of the curved surface 31, the bottom surface of the recess 27 is generally formed at an angle that is shallower on the outer end face 19 side and deeper on the inner end face 17 side. In other words, the recess 27 gradually deepens from the outer end face 19 side to the inner end face 17 side. Additionally, the bottom surface of the recess 27 has a portion that has a height difference relative to the flat surface 29 that is less than or equal to the diameter of the wire 23. This is also referred to... Figure 4 This is particularly effective in the heat-pressing process described later. In the illustrated embodiment, the bottom surface of the recess 27, except for a limited portion near the inner end face 17, has a height difference relative to the flat surface 29 that is less than or equal to the diameter of the wire 23. Here, more precisely, the diameter of the wire 23 refers to the diameter of the portion of the wire 23 wound around the core portion 12 (where the wire 23 is not flattened radially).

[0043] Furthermore, the axial direction of the wire 23 may not be parallel to the flat surface 29. Therefore, the height difference between the bottom surface of the recess 27 and the flat surface 29 is the height difference measured along the radial direction of the wire 23. More accurately, it should be understood as the diameter of the portion of the wire 23 wound around the core portion 12.

[0044] In addition, such as Figure 1 and Figure 2 As shown, the flat surface 29 exists with respect to the recess 27. This is also in reference to... Figure 4 It is more effective in the hot pressing process described later.

[0045] like Figure 4 As shown, during the hot-pressing process, the end of the wire 23 that is connected to the terminal electrode 25 is received in the recess 27 in a state that extends from the inner end face 17 side toward the outer end face 19 side, and exists along the arc surface 31. Figure 4 In the image, a portion of the wire 23 before heat pressing is shown by dashed lines.

[0046] Next, the heat-pressing joint 33 descends towards the mounting surface of the flange portion 13 in the direction indicated by arrow 34, heating and pressing the end of the wire 23 simultaneously, causing the wire 23 to begin the heat-pressing process of plastic deformation as shown by the solid line. Here, the heat-pressing temperature varies depending on the material of the insulation film of the wire 23, but is selected as, for example, a temperature of about 300 to 500°C. In addition, when the diameter of the wire 23 is 15 to 200 μm, the heat-pressing pressure is selected as, for example, a pressure of about tens to several kgf.

[0047] In the initial stage of the above-mentioned hot-pressing process, the insulating film at the end of the wire 23 is decomposed and removed by the heat imparted by the hot-pressing joint 33.

[0048] Next, the heat-pressed joint 33 descends further in the direction of arrow 34, and the end of the wire 23 is radially crushed between the heat-pressed joint 33 and the arc surface 31. As a result, as Figure 4 As shown by the solid line, the ends of wire 23 undergo plastic deformation, are heated, and joined with terminal electrode 25. Simultaneously, wire 23 is cut at the edge where the outer end face 19 of flange 13 intersects with the arc surface 31. This completes the hot-pressing process. After the hot-pressing process, the ends of wire 23 are joined with terminal electrodes 25 and 26 respectively, as shown in the diagram. Figure 1 As shown.

[0049] like Figure 4 As shown, if we observe the plastic deformation state of the wire 23 after the aforementioned hot-pressing process, the end thickness of the wire 23 continuously changes, being thinner on the outer end face 19 side and thicker on the inner end face 17 side. Specifically, in this embodiment, instead of the bottom surface of the recess 27 having a height difference with respect to the flat surface 29 that is less than or equal to the diameter of the wire 23, a limited portion near the inner end face 17 has a height difference with respect to the flat surface 29 that is larger than the diameter of the wire 23. Therefore, in the limited portion near the inner end face 17, there exists a region 35 where the wire 23 exhibits no plastic deformation whatsoever.

[0050] A region 36 exists adjacent to the outer end face 19 of the aforementioned region 35, where the thickness of the end of the wire 23 gradually decreases continuously. This continuous change in thickness is caused by the curved surface 31. Regarding the region 36 where the thickness of the end of the wire 23 continuously changes, it is possible to achieve a region where the pressure continuously changes along the length of the wire 23, from a portion where the heat-pressing joint 33 presses the wire 23 relatively weakly to a portion where the pressure of the heat-pressing joint 33 gradually increases and presses the wire 23 more strongly. By increasing the aforementioned radius of curvature r of the curved surface 31 to be larger than the distance between the inner end face 17 and the outer end face 19, a slower change in pressure can be achieved over a larger area within region 36.

[0051] More specifically, in Figure 4 In the state following the heat-pressing process, the wire 23 undergoes significant plastic deformation on the outer end face 19 side of the flange portion 13 to bond with the terminal electrode 25. However, due to the relatively strong pressure applied to the wire 23, the wire 23 exhibits relatively high peel strength relative to the terminal electrode 25. On the other hand, the pressure applied to the wire 23 on the inner end face 17 side of the flange portion 13 is relatively low, resulting in only relatively low peel strength for the wire 23 relative to the terminal electrode 25. Conversely, the amount of crushing on the wire 23 is relatively small, thus the strength of the wire 23 itself is maintained with almost no reduction.

[0052] Here, let's consider a scenario where an external force is applied to peel off the wire 23. In this case, two types of damage are possible. One is that the wire 23 peels off from the terminal electrode 25 due to poor crimping. The other is that the wire 23 becomes too thin due to heat crimping, resulting in wire breakage.

[0053] exist Figure 4 In the region 36, where the thickness varies continuously, the portion on the outer end face 19, where the crimping strength is relatively high and the wire 23 itself is thin, is smoothly connected along the arc surface 31 to the portion where the crimping strength is relatively low but the wire 23 itself has higher strength due to less compression. Therefore, when a peeling force is applied from the outside, there will inevitably be a point in the middle of region 36 where the force is resisted, making peeling "difficult" and "the wire 23 unlikely to break," thus applying appropriate pressure. Therefore, unintentional cutting of the wire 23 is prevented, and a stable and adequate heat crimping can be achieved.

[0054] During the aforementioned heat-pressing, the flat surface 29 formed on the mounting surface 21 of the flange portion 13, excluding the recess 27, serves to prevent excessive pressure from the heat-pressed joint 33. That is, the descending tail end of the heat-pressed joint 33 in the direction of arrow 34 is defined by the flat surface 29. As in this embodiment, if the flat surface 29 exists in the space between the recess 27 and the flange portion 13, the descending tail end of the heat-pressed joint 33 can be stably defined. Furthermore, regarding the width dimension of the drum-shaped core 15, it is preferable that the recess 27 is at least one times the length of the wire 23 and less than two-thirds the length of the flange portion 13.

[0055] Next, refer to Figure 5 The second embodiment of the present invention will be described. Figure 5 Is with Figure 4 The corresponding figure shows a portion of the drum-shaped core 15a and the wire 23 of the coil component. Figure 5 In the middle, to and Figure 4Elements that are equivalent to those shown are given the same reference numerals, and repeated descriptions are omitted.

[0056] Figure 5 The embodiment shown is characterized in that the bottom surface of the recess 27 has a height difference relative to the flat surface 29 that is less than or equal to the diameter of the portion of the wire 23 wound around the core portion 12. In this case, it is preferable that the end of the bottom surface of the recess 27 on the inner end face 17 side has a height difference relative to the flat surface 29 that is 0.5 to 1 times the diameter of the wire 23.

[0057] According to this embodiment, there is essentially no region 35 in the wire 23 where there is absolutely no plastic deformation (see reference). Figure 4 The region 36, where the thickness of the end of the wire 23 gradually decreases and continuously varies, exists throughout the entire area of ​​the recess 27.

[0058] In this embodiment, as described above, there is essentially no region 35 where the wire 23 is completely free from plastic deformation. Therefore, in the region 36 where the thickness of the wire 23 gradually decreases, the variation in the thickness of the wire 23 may be smaller than in the first embodiment described above. Therefore, in order to find a position within region 36 that is "not easily peeled" and "not easily broken" against external peeling forces, i.e., a position where appropriate pressure is applied, the height difference between the end of the bottom surface of the recess 27 on the inner end face 17 side and the flat surface 29 needs to be increased to a certain extent. Therefore, this height difference is preferably 0.5 times or more the diameter of the wire 23, as described above.

[0059] Next, refer to Figure 6 The third embodiment of the present invention will be described. Figure 6 Is with Figure 3 The corresponding figure shows a portion of the drum-shaped core 15b of the coil component. Figure 6 In the middle, to and Figure 3 Elements that are equivalent to those shown are labeled with the same reference numerals, and repeated descriptions are omitted.

[0060] Figure 6 The embodiment shown is characterized in that the bottom surface of the recess 27 is not entirely formed by the arc surface 31, but the arc surface 31 stops at the end of the bottom surface of the recess 27 on the side of the inner end face 17.

[0061] As in this embodiment, it is not limited to the case where the bottom surface of the recess 27 is entirely formed by the arc surface 31, and the same effect as in the aforementioned embodiment can be obtained.

[0062] Next, refer to Figure 7 The fourth embodiment of the present invention will now be described. Figure 7 Is with Figure 3The corresponding diagram, but with Figure 3 Compared to the previous case, a portion of the drum-shaped core 15c of the coil component is shown in a more enlarged manner. Figure 7 In the middle, to and Figure 3 Elements that are equivalent to those shown are labeled with the same reference numerals, and repeated descriptions are omitted.

[0063] exist Figure 7 In the embodiments shown, with Figure 6 The situation is the same in the embodiment shown; the bottom surface of the recess 27 is entirely formed by the arc surface 31. Figure 7 In the illustrated embodiment, the arc surface 31 stops at the end of the bottom surface of the recess 27 on the side of the outer end face 19, and a portion of the flat surface 29 exists on the side of the outer end face 19 of the recess 27 via a step D. Furthermore, an angular edge 38 is formed at the edge of the flat surface 29 on the side of the outer end face 19, where the step D is formed.

[0064] The aforementioned step D is preferably more than 1 / 10 and less than 1 / 3 of the diameter of the portion of the wire 23 wound around the core portion 12. According to this embodiment, when the wire 23 is heat-pressed toward the terminal electrode 25, stress concentrates at the edge 38, thus allowing the excess portion at the end of the wire 23 to be cut off with less pressing force, and enabling it to be connected to the heat-pressing connector 33 (see reference 1) for heat pressing. Figure 4 The size and shape of the wire 23 can be controlled more reliably, regardless of its application location, to prevent excessive crushing of the wire 23.

[0065] Reference Figures 5-7 The second to fourth embodiments have been described respectively, but... Figures 5-7 In this diagram, only the structure on the side of the first flange portion 13 is illustrated, and only the structure on the side of the first flange portion 13 is described. Although the structure on the side of the second flange portion 14 is omitted from the description, it is symmetrical to the structure on the side of the first flange portion 13.

[0066] According to the embodiments described above, the end of the wire 23 connected to the terminal electrodes 25 and 26 can be formed such that the pressure applied to the wire 23 in the heat-pressing process becomes stronger and continuously varied closer to the front end of the wire 23, and in other words, the pressure applied to the wire 23 in the heat-pressing process becomes weaker and continuously varied further away from the front end of the wire 23.

[0067] Therefore, within a certain length range of the end of the wire 23 connected to the terminal electrodes 25 and 26, the pressure during heat pressing can be continuously varied along the length direction of the wire 23. Thus, within this length range, there must be a portion where the pressing strength is improved compared to the conventional construction. As a result, in the coil component 11, both preventing wire breakage and ensuring stable heat pressing can be achieved simultaneously.

[0068] The present invention has been described above in relation to the embodiments illustrated, but various other embodiments can be implemented within the scope of the present invention.

[0069] For example, although not shown, a plate-shaped core can be provided to connect the surfaces of the first flange portion 13 and the second flange portion 14 of the drum-shaped core 15 that are opposite to their respective mounting surfaces 21 and 22. When both the drum-shaped core and the plate-shaped core are made of magnetic materials, the drum-shaped core and the plate-shaped core form a closed magnetic circuit.

[0070] Furthermore, while the above-described embodiments pertain to coil components with a single wire, the present invention can also be applied to coil components with multiple wires, such as those constituting a common-mode choke coil or a transformer coil component. Therefore, the number of wires can be varied depending on the function of the coil component, and correspondingly, the number of terminal electrodes provided on each flange is not limited to one, but can be multiple. When multiple terminal electrodes are provided on each flange, the multiple terminal electrodes are electrically isolated from each other in a manner arranged in the width direction of each flange. Therefore, multiple recesses are arranged in a manner arranged in the width direction of each flange.

[0071] In addition, the arc surfaces 31 and 32 may be formed only on a portion of the bottom surfaces of the recesses 27 and 28, or only on a portion of the bottom surfaces of the recesses 27 and 28. In the latter case, where the arc surfaces 31 and 32 are only formed on a portion of the bottom surfaces of the recesses 27 and 28, firstly, the arc surfaces 31 and 32 may be formed only on the regions of the flanges 13 and 14 towards their respective inner end faces 17 and 18; secondly, the arc surfaces 31 and 32 may be formed only on the regions towards their outer end faces 19 and 20; and thirdly, the arc surfaces 31 and 32 may be formed only in the central portion of the recesses 27 and 28. Furthermore, in all three cases, the portion of the bottom surfaces of the recesses 27 and 28 that is not formed by the arc surfaces 31 and 32 may be a surface that has an angle relative to the mounting surfaces 21 and 22, or a surface that is parallel to the mounting surfaces 21 and 22.

[0072] In addition, as shown in the embodiment, the convex shape of the arc surfaces 31 and 32 makes it easier to crimp the wire 23, which is preferred, but they can also be concave.

[0073] Furthermore, the scope of the present invention is not limited to the above-described embodiments, but also includes partial replacement of structures between different embodiments, or combination of the above structures.

Claims

1. A coil component, characterized in that, have: A drum-shaped core having a core portion and a flange portion provided at the end of the core portion; Wire, wound around the core portion; and Terminal electrodes, which are used for end connections of the wire. The flange portion has: an inner end face facing the core portion and positioning the end of the core portion; an outer end face facing the outer side opposite to the inner end face; and a mounting surface connecting the inner end face and the outer end face, wherein the mounting surface faces the mounting substrate during installation. The terminal electrode is disposed on the mounting surface of the flange portion. The mounting surface has a recess that is open only on the inner end face side and a flat surface other than the recess. The portion of the mounting surface located on the outer end face side of the recess is a flat surface. The end of the wire is received within the recess from the inner end face side toward the outer end face side, and its thickness continuously varies, being thinner on the outer end face side and thicker on the inner end face side.

2. The coil component according to claim 1, characterized in that, The height difference between the bottom surface of the recess and the flat surface is less than or equal to the diameter of the portion of the wire wound around the core.

3. The coil component according to claim 1 or 2, characterized in that, The recess gradually deepens from the outer end face to the inner end face.

4. The coil component according to claim 1 or 2, characterized in that, An arc surface is formed at least partially on the bottom surface of the recess, the arc surface having a central axis along a line extending in the width direction parallel to the mounting surface and the outer end face and having a radius of curvature larger than the distance between the inner end face and the outer end face.

5. The coil component according to claim 4, characterized in that, The central axis of the arc surface is located on the surface along the outer end face or at a position further out than the surface along the outer end face.

6. The coil component according to claim 4, characterized in that, The thickness of the end of the wire varies continuously along the arc surface.

7. The coil component according to claim 1 or 2, characterized in that, In the mounting surface, a portion of the flat surface is located on the outer end face side of the recess via a step, and the edge formed by the step in the flat surface on the outer end face side forms an angular edge.

8. The coil component according to claim 7, characterized in that, The step is more than 1 / 10 and less than 1 / 3 of the diameter of the portion of the wire wound around the core.

9. The coil component according to claim 1 or 2, characterized in that, The flat surface exists through the recess.

10. The coil component according to claim 1 or 2, characterized in that, The terminal electrode covers the entire mounting surface.

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