METHOD FOR MANUFACTURING A COIL COMPONENT

Abstract

Method for manufacturing a coil component (1) comprising the following steps: a step to provide a wire comprising a linear central conductor (3a) and an insulating coating (3b) covering a circumferential surface of the central conductor; a step to provide a metal terminal which is to be electrically connected to the central conductor (3a) at an end section of the wire and which has a surface on which a tin-containing film (27) containing tin is arranged and over which at least the end section of the wire is to be arranged; and a step to weld the central conductor (3a) of the wire to the metal terminal by irradiating at least the tin-containing film (27) with a laser beam to perform welding with the end section of the wire, wherein the end section of the wire is arranged along the tin-containing film; wherein in the step of welding the central conductor (3a) of the wire to the metal terminal the laser beam is emitted, the end section of the wire being in contact with the tin-containing film (27); wherein the step of welding the central conductor (3a) of the wire to the metal terminal further comprises flattening the end section of the wire into an elongated shape and temporarily securing the end section of the wire to the metal terminal by thermocompression bonding the end section of the wire to the tin-containing film (27) before the step of irradiation with the laser beam takes place, and wherein the end section of the wire is brought into contact with the tin-containing film (27) such that a principal axis direction of a subsection of the elongated shape of the wire runs along a surface of the tin-containing film.

Description

[0001] The present invention relates to a method for manufacturing a coil component and in particular to a method for joining a wire and a metal connection together by laser welding, as well as to a connecting structure.

[0002] In JP 2007 - 150 032 A, reference is made to the provision of a coil-part connection device which ensures the welding of a coil and a metal connection and is intended to improve the reliability of the connection.

[0003] In JP 2011 - 243 685 A, reference is made to the provision of a coil component which is intended to ensure sufficient component accuracy even when miniaturized, by containing a magnetic substance in a main part consisting of a green body.

[0004] In JP 2002 - 117 913 A, reference is made to a welded joint and its joining method for welding a metal connection with one metal wire or two metal wires through an intense heat source.

[0005] DE 10 2009 013 110 B4 refers to a laser-welded structure comprising a conductor, a conductive component and a weld part.

[0006] An interesting method for the present invention is disclosed, for example, in Japanese patent JP 4 184 394 B2. Fig. 5, Fig. 6, Fig. 7 and Fig. 8 are quoted from Japanese patent JP 4 184 394 B2 and each corresponds to Fig. 2, Fig. 3, Fig. 4 and Fig. 5 of Japanese patent JP 4 184 394 B2. Fig. 5 to Fig. Figure 8 illustrates a flange section 71, which is part of a core contained in a coil component, a metal terminal 72 arranged on the same, and an end section of a wire 73 connected to the metal terminal 72.

[0007] As in Fig. 5 and Fig. As well illustrated in Figure 8, the wire 73 comprises a linear central conductor 74 and an insulating coating 75 covering the circumferential surface of the central conductor 74. The metal terminal 72 is formed using a metal plate, for example made of phosphor bronze, and comprises a base 77 located on an outer end surface 76 of the flanged section 71, and a receiving section 79 extending from the base 77 over a curved section 78, which receives the end section of the wire 73. As shown in Fig. As is well illustrated in Figure 5, the metal connection 72 also includes a welded part 81 extending from the receiving section 79 over a first bent section 80 and welded to the central conductor 74 of the wire 73, and a holding section 83 extending from the receiving section 79 over a second bent section 82 and holding the wire 73 for positioning purposes.

[0008] Fig. 5 and Fig. Figure 6 illustrates the state of the welded part 81 before a welding process is carried out, and Fig. 7 and Fig. Figure 8 illustrates the state of the same after the welding process has been carried out. Fig. 7 and Fig. Figure 8 also illustrates an extension section 84 produced by welding. The extension section 84, also referred to as a weld bead or weld lenticular section, is produced by forming molten metal into a spherical shape due to surface tension during welding, where it then cools and solidifies.

[0009] The welding process will now be described in detail. Before the welding process, the weld part 81 and the holding section 83 are not bent towards the receiving section 79 of the metal connection 72 and are not facing the receiving section 79. Fig. Figure 5 illustrates a condition in which the holding section 83 faces the receiving section 79 and the weld part 81 is not bent towards the receiving section 79.

[0010] The wire 73 is first placed on the receiving section 79 of the metal connector 72. To temporarily maintain this state, the retaining section 83 is bent from the second bent section 82 towards the receiving section 79 so that the wire 73 is positioned between the receiving section 79 and the retaining section 83.

[0011] The following describes how in Fig. As illustrated in Figure 5, a section of the insulating coating 75 of the wire 73 is removed, which is closer to one end than a section located between the receiving section 79 and the holding section 83. The section of insulating coating 75 is removed, for example, by laser beam irradiation. As shown in Fig. 5 and Fig. As is well illustrated in Figure 8, a section of the insulating coating 75, which is in contact with the receiving section 79, is not removed and remains.

[0012] The following describes how in Fig. Figure 6 illustrates that the weld part 81 is bent from the first bent section 80 towards the receiving section 79, and the wire 73 is arranged between the weld part 81 and the receiving section 79.

[0013] The central conductor 74 of the wire 73 and the weld part 81 are subsequently welded together. More precisely, laser beam welding is used. The weld part 81, which is located in the Fig. The illustrated state (6) is irradiated with a laser beam, and the central conductor 74 of the wire 73 and the welded part 81 are thereby melted. As in Fig. 7 and Fig. As illustrated in Figure 8, surface tension causes a liquefied weld lens section to be formed into a spherical shape. The extension section 84 is then formed as described above.

[0014] During the welding process described above, the molten metal protrudes from the receiving section 79 of the metal connection 72 and in some cases extends to the bent section 78 or the base 77. As a result, the heat from such excessive welding causes the metal connection 72 to deform undesirably.

[0015] According to the method disclosed in Japanese patent JP 4 184 394 B2, the section of insulating coating 75 that is in contact with the receiving section 79 is not removed and remains as described above to prevent the excessive welding described above. It can therefore be argued that a provisional measure according to the method disclosed in Japanese patent JP 4 184 394 B2 is being considered to prevent excessive welding.

[0016] The object of the present invention is to create a method and a coil component with improved characteristics.

[0017] This problem is solved by a method for manufacturing a coil component according to claim 1.

[0018] A metal terminal formed using a metal plate typically has a tinned surface and a non-tinned surface, where no tinning is performed. More specifically, the tinned surface is the surface of the metal terminal that is soldered to a mounting substrate when a coil component is attached, to ensure good wettability. The non-tinned surface is the other surface of the metal terminal that adheres to a core with an adhesive. The tinned surface is more likely to melt a tinning film at the temperature used for soldering by molten metal, thus preventing adhesion between the metal terminal and the core.

[0019] The metal connector 72, which is in Fig. 5 to Fig. Figure 8 illustrates this and is described in more detail below. One surface of the metal connection 72, designated “A”, is the tinned surface, which is soldered. One surface of the metal connection 72, designated “B”, is the non-tinned surface and adheres to the core, more precisely to the flange section 71, with the bonding agent.

[0020] Attention is focused on the weld part 81, which is irradiated with the laser beam during the welding process. As in Fig. As illustrated in Figure 6, surface B, that is, the untinned surface of the welded part 81, faces outwards. Accordingly, the laser beam is directed towards the untinned surface. The metal terminal 72, for example, consists of a copper alloy such as phosphor bronze, and the laser beam is directed towards the copper alloy, which is the base material of the metal terminal 72.

[0021] However, copper has a relatively low laser beam absorption efficiency. Consequently, it takes a long time to reach the temperature of approximately 1000 °C at which the weld part 81 can be melted and welded. Therefore, the metal terminal 72 and the wire 73 are exposed to excessive heat. This excessive heat causes pyrolysis of the adhesive bonding the metal terminal 72 to the flange section 71 and results in a thermal shock to the adhesive, leading to the metal terminal 72 detaching from the core, pyrolysis of the insulating coating 75 of the wire 73, and a change in the quality of the insulating coating 75.

[0022] Accordingly, it is an object of the present invention to solve the problems described above and to create a method for manufacturing a coil component that enables laser welding to be completed in a shorter time.

[0023] According to preferred embodiments of the present invention, the fact that tin has a higher absorption efficiency of a laser beam than copper is exploited.

[0024] According to preferred embodiments of the present invention, a method for manufacturing a coil component comprises a step for providing a wire comprising a linear central conductor and an insulating coating covering a circumferential surface of the central conductor, a step for providing a metal terminal to be electrically connected to the central conductor at an end section of the wire and having a surface on which a tin-containing film containing tin is arranged and over which at least the end section of the wire is to be arranged, and a step for welding the central conductor of the wire to the metal terminal by irradiating the tin-containing film with a laser beam, wherein the end section of the wire is arranged along the tin-containing film.In the step of welding the wire's central conductor to the metal terminal, the laser beam is emitted while the wire's end section is in contact with the tin-containing film. This welding step further includes flattening the wire's end section into an elongated shape and temporarily securing it to the metal terminal by thermal compression bonding the wire's end section to the tin-containing film before the laser beam irradiation. The wire's end section is then brought into contact with the tin-containing film such that a principal axis of a portion of the wire's elongated shape runs along a surface of the tin-containing film.

[0025] According to preferred examples of the present invention, a coil component produced by such a method comprises a wire comprising a linear central conductor and an insulating coating covering a circumferential surface of the central conductor, and a metal terminal electrically connected to the central conductor of the wire and comprising a receiving section that receives the end section of the wire.

[0026] A tin-containing film is arranged on a surface of the metal terminal that faces in the same direction as a surface of the receiving section over which the wire end section is located. The receiving section comprises a welded section to which the central conductor is welded, and an adjacent non-welded section. The welded and non-welded sections are arranged in that order from one end to an intermediate section of the wire in a longitudinal direction. The welded section includes a weld bead section formed integrally by welding the central conductor and the receiving section, and which projects from the surface of the receiving section over which the wire end section is located.Tin is distributed along or near an imaginary extensional surface of the tin-containing film extending within the weld lens section.

[0027] According to the preferred embodiment of the present invention, the temperature of the metal terminal can reach a temperature at which it can be welded in a relatively short time, since the absorption efficiency of the laser beam irradiating the tin-containing film is relatively high. Therefore, it is possible to prevent the metal terminal and the wire from being exposed to excessive heat during welding. Consequently, thermal damage to the metal terminal and the wire in the coil component can be reduced.

[0028] Further features, elements, characteristics and advantages of the present invention will become apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.

[0029] Preferred embodiments of the present invention are explained in more detail below with reference to the accompanying drawings. These show: Fig. 1A a perspective view of a coil component according to an embodiment of the present disclosure from a relatively higher position; Fig. 1B a perspective view of the coil component from a relatively lower position; Fig. 2 an enlarged sectional view of a first wire which is in the Fig. 1A and Fig. The coil component illustrated in 1B is included; Fig. 3A and Fig. 3B schematically depicts a welding process in which the first wire is connected to a first metal terminal in the coil component, which is in Fig. 1A and Fig. 1B illustrates how it is electrically connected; Fig. 4 An enlarged view of a section of the electrical contact between the first wire and the first metal terminal obtained during the welding process, which is described in Fig. 3A and Fig. 3B illustrates this; Fig. 5 a perspective view of a flange section of a core contained in a coil component disclosed in Japanese patent JP 4 184 394 B2, a metal terminal arranged thereon, and a wire connected to the metal terminal, illustrating a pre-welding condition in which the wire is arranged and temporarily secured between a receiving section and a holding section, and a weld part is not bent towards the receiving section; Fig. 6 a perspective view that Fig. 5 corresponds to, and illustrates a state prior to welding, in which the welded part, from a first bent section towards the receiving section, is in the state that is shown in Fig. 5 is illustrated, is bent and the wire is positioned between the welding part and the receiving section; Fig. 7 in accordance with Fig. 5 a state in which the welded part is in the state that is in Fig. Figure 6 illustrates the process of irradiation, whereby a central conductor of the wire and the welded part have been welded together; and Fig. 8 an enlarged sectional view of a welded section which is in Fig. Figure 7 illustrates this.

[0030] The entire structure of a coil component 1, which can be manufactured using a method according to an embodiment of the present invention, is described with reference to Fig. 1A and Fig. 1B described. The ones in Fig. 1A and Fig. The coil component 1 illustrated in Figure 1B, for example, forms a common-mode choke coil. Fig. 1A and Fig. In 1B, an illustration of the main components of two wires is omitted.

[0031] The coil component 1 comprises a drum-shaped core 2. A first wire 3 and a second wire 4 are wound around the drum-shaped core 2. The drum-shaped core 2 comprises a winding core section 5 extending in an axial direction X, and a first flange section 6 and a second flange section 7 arranged on end sections of the winding core section 5 that are opposite each other in the axial direction X. The drum-shaped core 2 is preferably made of ferrite. The drum-shaped core 2 can be made of a non-conductive material other than ferrite, for example, a non-magnetic material such as aluminum or a resin containing ferrite powder or magnetic metal powder.

[0032] The winding core section 5, the first flange section 6, and the second flange section 7, contained within the drum-shaped core 2, have, for example, a substantially quadrilateral prismatic shape with a substantially square cross-sectional shape. Edge sections of the winding core section 5, the first flange section 6, and the second flange section 7, which have a substantially quadrilateral prismatic shape, are preferably chamfered, although this is not illustrated. The cross-sectional shape of the winding core section 5, the first flange section 6, and the second flange section 7 can, instead of being square, have a substantially polygonal shape, for example, a hexagon, a substantially circular shape, or a substantially elliptical shape, or a combination thereof.

[0033] The first flange section 6 has a bottom surface 8 extending in the axial direction X, which is intended to face a fastening substrate during fastening, and an upper surface 10 opposite the bottom surface 8. The first flange section 6 also has an inner end surface 12a extending upwards from the bottom surface 8 in a direction perpendicular to the fastening substrate and facing the winding core section 5, an outer end surface 12b extending upwards from the bottom surface 8 in a direction perpendicular to the fastening substrate and facing in the opposite direction to the winding core section 5, and a first side surface 12c and a second side surface 12d connecting the inner end surface 12a and the outer end surface 12b.

[0034] Similar to the first flange section 6, the second flange section 7 has a bottom surface 9 extending in the axial direction X and which is to face the fastening substrate during fastening, and an upper surface 11 opposite the bottom surface 9.The second flange section 7 also has an inner end surface 13a extending upwards from the bottom surface 9 in the direction perpendicular to the mounting substrate and facing the winding core section 5, an outer end surface 13b extending upwards from the bottom surface 9 in the direction perpendicular to the mounting substrate and facing in the opposite direction to the winding core section 5, and a first side surface 13c and a second side surface 13d connecting the inner end surface 13a and the outer end surface 13b.

[0035] Steps formed to project along the upper sides of the outer end surfaces 12b and 13b of the flange sections 6 and 7 are not strictly necessary and may not be formed.

[0036] A first metal connection 16 and a third metal connection 18 are spaced apart and attached to the first flange section 6 with an adhesive. A second metal connection 17 and a fourth metal connection 19 are spaced apart and attached to the second flange section 7 with an adhesive. Each of the first to fourth metal connections 16 to 19 is typically manufactured by processing a metal plate made of a copper alloy such as phosphor bronze or tough-polished copper. The metal plate has a thickness of not less than 0.10 mm and not more than 0.15 mm, for example, a thickness of approximately 0.1 mm.

[0037] As in Fig. 1A and Fig. As illustrated in Figure 1B, each of the first metal connection 16 and the third metal connection 18 comprises a base section 20 extending along the bottom surface 8 of the first flange section 6, and a rising section 23 connected to the base section 20 via a curved section 22 covering an edge line section 21 along which the outer end surface 12b and the bottom surface 8 of the first flange section 6 intersect, and which extends along the outer end surface 12b of the first flange section 6. Each of the first metal connection 16 and the third metal connection 18 also comprises a receiving section 24 extending from the base section 20 and receiving an end section of the first wire 3 or the second wire 4. The receiving section 24 is preferably spaced slightly apart from the drum-shaped core 2.

[0038] In Fig. 1A and Fig. Figure 1B shows the second metal terminal 17 and the fourth metal terminal 19 partially illustrated. The first metal terminal 16 and the fourth metal terminal 19 described above have the same shape. The second metal terminal 17 and the third metal terminal 18 described above also have the same shape. Accordingly, the reference numerals 20, 22, 23, and 24, which denote the base section, the bent section, the rising section, and the receiving section of each of the first metal terminal 16 and the third metal terminal 18 described above, are also used, as needed, to denote those of the second metal terminal 17 and the fourth metal terminal 19.

[0039] The first end of the first wire 3 is electrically connected to the receiving section 24 of the first metal terminal 16. The second end of the first wire 3, opposite the first end, is electrically connected to the receiving section 24 of the second metal terminal 17. The first end of the second wire 4 is electrically connected to the receiving section 24 of the third metal terminal 18. The second end of the second wire 4, opposite the first end, is electrically connected to the receiving section 24 of the fourth metal terminal 19. These are electrically connected by laser welding using a laser beam. Fig. 1A and Fig. Figure 1B illustrates weld lens sections 25, which bulge out into a hemispherical shape as a result of laser welding. The processes for joining the first to fourth metal terminals 16 to 19 and the first and second wires 3 and 4 by laser welding, as well as the structure of each weld lens section 25, will be described later with reference to Fig. 3A, Fig. 3B and Fig. 4 described in more detail.

[0040] Fig. Figure 2 is an enlarged sectional view of the first wire 3 contained within the coil component 1. The first wire 3 and the second wire 4 have essentially the same cross-sectional shape. The first wire 3, which is contained in Fig. The second wire 4, which is illustrated in Figure 2, is described below; however, a description of the second wire 4 is omitted.

[0041] As in Fig. As illustrated in Figure 2, the first wire 3 typically has a substantially circular cross-sectional shape and comprises a linear central conductor 3a and an insulating coating 3b covering the circumferential surface of the central conductor 3a, which consists of an electrically insulating resin. The diameter D of the central conductor 3a is, for example, not less than 28 µm and not more than 50 µm. The thickness T of the insulating coating 3b is, for example, not less than 3 µm and not more than 6 µm. The central conductor 3a is, for example, made of a highly conductive metal such as copper. The insulating coating 3b consists of a resin containing at least one imide linkage, such as polyamide-imide or imide-modified polyurethane.

[0042] The first wire 3 and the second wire 4 are wound spirally in the same direction around the winding core section 5, although an illustration of this is shown in Fig. 1A and Fig. 1B is omitted. More precisely, the first wire 3 and the second wire 4 can be wound to form two layers, with either the first wire 3 or the second wire 4 wound on the inside and the other wire on the outside, or they can be wound to form a single layer, with the windings of each wire arranged alternately and parallel to each other along the axis of the core section 5. In the latter case, the two wires 3 and 4 are wound simultaneously in the manner of a bifilar winding.

[0043] After a process for winding the first wire 3 and the second wire 4 is completed, the processes for connecting the first wire 3 and the second wire 4 and the first to fourth metal terminals 16 to 19 are carried out as described below.

[0044] The process for connecting the first wire 3 to the first metal terminal 16 is described below with reference to Fig. 3A and Fig. 3B is described representatively. Accordingly, in the following description, the “first wire” is simply referred to as the “wire”, and the “first metal terminal” is simply referred to as the “metal terminal”. Fig. 3A and Fig. Figure 3B schematically illustrates the receiving section 24 of the metal connector 16 and the end section of the wire 3. Fig. 3A and Fig. In 3B, a laser beam 28 is directed from top to bottom. This relationship in the vertical direction is opposite to that in Fig. 1A and Fig. 1B.

[0045] Immediately after completing the wrapping process described above, as in Fig. As illustrated in Figure 3, the end section of the wire 3 is located on the receiving section 24. At this point, the wire 3 extends to reach an end 24a of the receiving section 24, and the end 24a is located near the end of the wire 3 in the longitudinal direction and is to be irradiated with the laser beam.

[0046] A tin-containing film 27, containing tin, is arranged on a surface of the receiving section 24, above which the end section of the wire 3 is arranged. The tin-containing film 27 has a thickness of, for example, not less than 0.5 µm and not more than 20 µm. The tin-containing film 27 is preferably formed in such a way as to form a tin plating film on a first main surface of the metal plate, which corresponds to the material of the metal terminal 16. The reason for this is that the tin-containing film 27 can be efficiently arranged on the receiving section 24.

[0047] The tin-containing film 27 is not limited to formation by plating and can be formed by printing a paste containing tin powder or by applying tin foil. However, if printing a paste containing tin powder is used, there are concerns that a solvent may evaporate and, due to the heat generated during a welding process described later, a void may be created in the weld lenticular section 25. To dispel these concerns, the tin-containing film 27 is preferably formed by plating or by applying the foil.

[0048] As in Fig. As illustrated in Figure 3A, the insulating coating 3b is removed from the entire circumference of the end section of the wire 3. The insulating coating 3b is removed, for example, using laser beam irradiation.

[0049] Subsequently, a thermocompression bond is performed between the end section of wire 3 and the tin-containing film 27. Consequently, as indicated by a dashed line in Fig. Figure 3A illustrates that, preferably, the end section of the wire 3 is flattened into an elongated shape and that the end section of the wire 3 is temporarily secured to the metal terminal 16 by melting the tin-containing film 27. At this point, the tin-containing film 27 is melted once, but its presence is maintained, and the end section of the wire 3 is brought into contact with the tin-containing film 27 such that the principal axis direction of a partial section of the elongated shape runs along a surface of the tin-containing film 27. This makes it possible to bring the end section of the wire 3 and the receiving section 24 into close contact with each other, and the contact area between them can be relatively wide.Accordingly, in the welding process described later, heat that causes the receiving section 24 to melt can be quickly directed to the central conductor 3a of the wire 3, and the welding can be completed in a shorter time.

[0050] According to the exemplary embodiment, the end section of the wire 3 and the receiving section 24 are preferably, but not necessarily, brought into close contact with each other. If the receiving section 24 and the end section of the wire 3 are in partial contact with each other, heat that causes the receiving section 24 to melt is conducted to the wire 3, and the welding can be completed more quickly.

[0051] The following will be explained, as again in Fig. As illustrated in Figure 3, at least the tin-containing film 27 is irradiated with the laser beam 28 to perform welding with the end section of the wire 3, which is arranged along the tin-containing film 27. At this point, the central conductor 3a of the wire 3, which is exposed by the insulating coating 3b, can also be irradiated with the laser beam 28. However, preferably only the tin-containing film 27 is irradiated. The reason for this is that the tin-containing film 27 has a higher absorption efficiency of the laser beam 28 than the central conductor 3a, which is made of copper, for example, and the temperature reaches the melting point of tin more quickly. Furthermore, liquefied tin further increases the absorption efficiency of the laser beam 28. In addition, it is unlikely that the central conductor 3a and the insulating coating 3b of the wire 3 will be affected by laser beam irradiation.

[0052] After the tin has liquefied and the absorption efficiency of the laser beam 28 has been further increased as described above, the base material of the receiving section 24, such as phosphor bronze, can be easily melted. Consequently, as in Fig. As illustrated in Figure 3B, the central conductor 3a is welded to the receiving section 24 in a short time. At this point, the molten central conductor 3a and the molten receiving section 24 are brought into a spherical shape due to surface tension acting upon them, and the weld nugget section 25 is formed. The weld nugget section 25 is formed in one piece by welding the central conductor 3a and the receiving section 24. The central conductor 3a is contained within the weld nugget section 25.

[0053] The irradiation conditions of the laser beam 28 include pulsed irradiation with, for example, a YAG laser, a pulse width of not less than 1.0 ms and not more than 10.0 ms, a wavelength of 1064 nm, and a peak power of not less than 0.5 kW and not more than 2.0 kW. The laser beam 28 is preferably emitted in the direction perpendicular to the surface of the tin-containing film 27, but may be inclined by ± 10 degrees with respect to the perpendicular direction.

[0054] It is preferred that the receiving section 24 be slightly spaced from the drum-shaped core 2, as described above. This structure is not strictly necessary. However, with this structure, it is unlikely that the elevated temperature of the receiving section 24 will be transferred to the drum-shaped core 2 during the welding process described above, and any adverse effect on the drum-shaped core 2 due to heat can be reduced.

[0055] Fig. Figure 4 is an enlarged view of a section of the electrical contact between the wire 3 and the metal terminal 16, which is located in the Fig. 3A and Fig. 3B illustrates the welding process. Fig. Figure 4 is a diagram created by tracing an image of a section of the electrical contact. Fig. 4 is the relationship in the vertical direction opposite to the one in Fig. 1A and Fig. 1B, as in Fig. 3A and Fig. 3B.

[0056] With reference to Fig. As a result of the welding process, the weld nugget section 25 and the receiving section 24, which remains after welding, are welded together and formed as a single piece. The central conductor 3a of the wire 3 is located between the receiving section 24 and the weld nugget section 25 and is contained within the weld nugget section 25.

[0057] More precisely, the receiving section 24 comprises a welded section 29, to which the central conductor 3a is welded, and a non-welded section 30 adjacent to the same, and the welded section 29 and the non-welded section 30 are arranged in this order from the end to an intermediate section of the wire 3 in the longitudinal direction. Fig. For simplicity, the boundary between the welded section 29 and the non-welded section 30 is illustrated by a dotted straight line in section 4. In practice, however, such a clear boundary is often not discernible.

[0058] The welded section 29 comprises the weld nugget section 25, which is formed integrally by welding the central conductor 3a and the receiving section 24, and which projects from the surface of the receiving section 24 above which the end section of the wire 3 is arranged, that is, the surface on which the tin-containing film 27 is arranged. Tin 27a is distributed along or near an imaginary extension line of the tin-containing film 27, which extends within the weld nugget section 25. Fig. Figure 4 illustrates the distribution of the tin 27a by markings x. The tin 27a originates from tin contained in the tin-containing film 27 and is distributed in a greater quantity near the surface of the receiving section 24 on which the tin-containing film 27 is arranged than in a greater quantity near the surface of the receiving section 24 opposite the surface on which the tin-containing film 27 is arranged, i.e., the surface on which the tin-containing film 27 is not arranged. This characteristic structure is obtained by irradiating the tin-containing film 27 with the laser beam, with the end section of the wire 3 arranged along the tin-containing film 27 to weld the central conductor 3a of the wire 3 to the metal terminal 16.

[0059] Attention is focused on the surface of the metal terminal 16 on which the tin-containing film 27 is arranged. In the description above, the tin-containing film 27 is arranged on the surface of the receiving section 24, above which the end section of the wire 3 is located. The tin-containing film 27 is typically arranged over an entire first main surface of the metal plate, which corresponds to the material of the metal terminal 16. The base section 20, the rising section 23, and the receiving section 24 are formed, for example, by bending the metal plate. In this case, as in Fig. As illustrated in Figure 1B, the surface of the receiving section 24, over which the end section of the wire 3 is positioned, faces in the same direction as the surface of the metal plate, which is bent to be soldered when the coil component 1 is attached. In other words, the tin-containing film 27, which is positioned on the surface of the receiving section 24, over which the end section of the wire 3 is positioned, extends to the surface that is to be soldered when the coil component 1 is attached.

[0060] Accordingly, the tin-containing film, which is arranged on the first main surface of the metal plate, has a function to reduce the laser welding time for joining the wire 3 to the receiving section 24 of the metal terminal 16, and a function to improve the solder wettability when the metal terminal 13 is soldered.

[0061] Nevertheless, the tin-containing film is typically not arranged on a second main surface of the metal plate. Accordingly, if the receiving section 24 is formed such that the metal plate is not bent, the base material of the metal terminal 16 is exposed on the surface of the receiving section 24 opposite the surface over which the end section of the wire 3 is arranged. As, for example, Fig. Viewed from 1B, the surface from which the base material is exposed, corresponding to the second main surface of the metal plate, is in contact with the adhesive by which the metal connector 16 adheres to the flange section 6 of the drum-shaped core 2. If a tin-containing film is arranged on this surface, there is a possibility that the tin-containing film will likely melt at a temperature at which soldering by melting is carried out, thus preventing adhesion. Accordingly, it is preferred that no tin-containing film is arranged on the surface of the receiving section 24, which faces the surface over which the end section of the wire 3 is arranged, and that the base material of the metal connector 16 is exposed from this surface.

[0062] The connection between the first metal terminal 16 and the first wire 3 is described above. The same procedures are carried out for the connections between the other metal terminals 17 to 19 and wire 3 or 4, and the same connection structure is obtained.

[0063] The use of a welding process and a welding structure, which are described above for the in Fig. 1A and Fig. As described in Figure 1B, coil component 1 prevents the metal terminals 16 to 19 and the wires 3 and 4 from being exposed to excessive heat. This prevents pyrolysis of the adhesive that bonds the metal terminals 16 to 19 to the flange sections 6 and 7, the occurrence of a thermal shock to the adhesive that would cause each of the metal terminals 16 to 19 to detach from the drum-shaped core 2, pyrolysis of the insulating coating 3B of each of the wires 3 and 4, and a change in the quality of the insulating coating 3B.

[0064] Following the above-described process for winding the first and second wires 3 and 4 and the processes for connecting the first and second wires 3 and 4 to the first to fourth metal terminals 16 to 19, as in Fig. 1A and Fig.As illustrated in Figure 1B, a plate core 32, made of ferrite for example, is bonded to the upper surfaces 10 and 11 of the first flange section 6 and the second flange section 7 using an adhesive. In this way, the drum-shaped core 2 and the plate core 32 form a closed magnetic circuit, and consequently, the inductance value can be improved.

[0065] A nickel film may be arranged at the first metal terminal 16 beneath the tin-containing film 27. The plate core 32 may be replaced by a magnetic resin plate or a metal plate, which may form a magnetic circuit. The coil component 1 may not include the plate core 32.

[0066] A coil component related to the present invention is described above based on the embodiment of the common-mode choke coil.

[0067] The number of wires contained in the coil component, the winding direction of the wires, and the number of metal connections can be changed, for example, according to the task of the coil component.

[0068] A coil component produced using a method according to the invention may not include a core such as the drum-shaped core.

Claims

[1] Method for manufacturing a coil component (1) comprising the following steps: a step to provide a wire comprising a linear central conductor (3a) and an insulating coating (3b) covering a circumferential surface of the central conductor; a step to provide a metal terminal which is to be electrically connected to the central conductor (3a) at an end section of the wire and which has a surface on which a tin-containing film (27) containing tin is arranged and over which at least the end section of the wire is to be arranged; and a step to weld the central conductor (3a) of the wire to the metal terminal by irradiating at least the tin-containing film (27) with a laser beam to perform welding with the end section of the wire, wherein the end section of the wire is arranged along the tin-containing film; wherein in the step of welding the central conductor (3a) of the wire to the metal terminal the laser beam is emitted, the end section of the wire being in contact with the tin-containing film (27); wherein the step of welding the central conductor (3a) of the wire to the metal terminal further comprises flattening the end section of the wire into an elongated shape and temporarily securing the end section of the wire to the metal terminal by thermocompression bonding the end section of the wire to the tin-containing film (27) before the step of irradiation with the laser beam takes place, and wherein the end section of the wire is brought into contact with the tin-containing film (27) such that a principal axis direction of a subsection of the elongated shape of the wire runs along a surface of the tin-containing film. [2] Method according to claim 1, wherein the tin-containing film (27) is a tin plating film.

Images