Patent Publication Number: US-2020279685-A1

Title: Coil component and electronic device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Japanese Patent Application No. 2019-036841, filed Feb. 28, 2019, the disclosure of which is incorporated herein by reference in its entirety including any and all particular combinations of the features disclosed therein. 
     BACKGROUND 
     Field of the Invention 
     The present invention relates to a coil component and an electronic device. 
     Description of the Related Art 
     It is known that, in order to electrically connect a conductive wire that forms a winding part with terminal electrodes formed by metal plates, the end parts of the conductive wire are joined with parts of the metal plates by means of arc welding or laser welding (refer to Patent Literatures 1 and 2, for example). 
     BACKGROUND ART LITERATURES 
     
         
         [Patent Literature 1] Japanese Patent Laid-open No. 2009-158777 
         [Patent Literature 2] Japanese Patent Laid-open No. 2018-41852 
       
    
     SUMMARY 
     When a conductive wire is joined with a part of a metal plate by means of welding, the fused portion rises and a welded part of rounded shape is formed. Conventional coil components having such welded parts have room for improvement in terms of size reduction. 
     An object of the present invention is to provide a coil component that permits size reduction. 
     The present invention is a coil component comprising: a substrate body; a winding part formed by a conductive wire wound around a part of the substrate body; and terminal electrodes, each having a foundation part constituted by a metal plate provided on the surface of a part of the substrate body, and a welded part formed on the foundation part through welding of a part of the metal plate to the conductive wire, where the conductive wire is electrically connected to a lead part led out from the winding part; wherein, based on a vertical line which passes through the peak point of the welded part where its height from the foundation part becomes the highest and which also crosses at right angles with the foundation part, the distance from the vertical line to the surface of the welded part as viewed in a direction parallel with the foundation part is longer at a point closer to the foundation part when viewed at least in one direction from the vertical line. 
     In the aforementioned constitution, the constitution may be such that the distance from the vertical line to the surface of the welded part as viewed in a direction parallel with the foundation part is longer at a point closer to the foundation part when viewed at least in the direction of the lead part side from the vertical line. 
     In the aforementioned constitution, the constitution may be such that the maximum distance from the vertical line to the surface of a welded part in parallel with the foundation part, as viewed in the direction of the lead part side, is longer than the distance from the foundation part to the peak point. 
     In the aforementioned constitution, the constitution may be such that: the welded part has a dome shape; and the angle formed between the portion of the foundation part contacted by the welded part and the surface of the welded part, is smaller than 60°. 
     In the aforementioned constitution, the constitution may be such that the welded part has a larger area for its cross-section orthogonal to the vertical line when the cross-section is closer to the foundation part. 
     In the aforementioned constitution, the constitution may be such that the welded part is formed on the foundation part in a manner contained within the range where the surface of the substrate body on which the welded part is provided overlaps the foundation part in plan view. 
     In the aforementioned constitution, the constitution may be such that the terminal electrodes each have an engagement part that locks the conductive wire. 
     In the aforementioned constitution, the constitution may be such that: the substrate body is a core that includes a winding core and flange parts provided at the end parts of the winding core in the axial direction; the terminal electrodes are placed on the flange parts; the winding part is formed by the conductive wire being wound around the winding core; and the lead parts are where the conductive wire is led out from the winding core to the terminal electrodes placed on the flange parts. 
     In the aforementioned constitution, the constitution may be such that: the substrate body includes a core that includes a winding core and flange parts provided at the end parts of the winding core in the axial direction, and an exterior core placed on the outer periphery of the core; the terminal electrodes are placed on the exterior core; the winding part is formed by the conductive wire being wound around the winding core; and the lead parts are where the conductive wire is led out from the winding core to the terminal electrodes placed on the exterior core. 
     The present invention is an electronic device comprising: the aforementioned coil component; and a circuit board on which the coil component is mounted. 
     According to the present invention, size reduction of a coil component becomes possible. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a cross-sectional view of a terminal electrode in a coil component according to the invention under the present application for patent, while  FIG. 1B  is a cross-sectional view of a terminal electrode in a coil component representing a comparative example. 
         FIG. 2  is a perspective view showing the coil component pertaining to the first embodiment of the invention under the present application for patent. 
         FIG. 3A  is a view from the arrow F 1  side, while  FIG. 3B  is a view from the arrow F 2  side, of the coil component in  FIG. 2 . 
         FIGS. 4A and 4B  are cross-sectional views of the coil component in  FIG. 2  at its flange parts. 
         FIG. 5  is a view of cross-section A-A of the terminal electrode in  FIG. 3A . 
         FIG. 6  is a drawing for explaining a terminal metal plate of the coil component in  FIG. 2 . 
         FIGS. 7A and 7B  are drawings explaining a method for manufacturing the coil component pertaining to the first embodiment of the invention under the present application for patent (part  1 ). 
         FIGS. 8A and 8B  are drawings explaining a method for manufacturing the coil component pertaining to the first embodiment of the invention under the present application for patent (part  2 ). 
         FIG. 9A  is a side view of a welded part, while  FIGS. 9B to 9D  are views of cross-sections A-A to C-C, respectively, in  FIG. 9A . 
         FIG. 10  is a cross-sectional view of a terminal electrode in the coil component pertaining to the second embodiment of the invention under the present application for patent. 
         FIG. 11  is a drawing of a coil component for single line (single wire). 
         FIG. 12  is a perspective view of a coil component having an exterior core provided on the outer periphery of a drum core. 
         FIG. 13  is a drawing showing an electronic device comprising the coil component pertaining to the first embodiment of the invention under the present application for patent. 
     
    
    
     DESCRIPTION OF THE SYMBOLS 
     
         
         
           
               10  Drum core 
               12  Winding core 
               14 ,  16  Flange part 
               18 ,  20 ,  22 ,  24  Concaved part 
               30  Winding part 
               32 ,  34  Conductive wire 
               32 A,  32 B,  34 A,  34 B Tip face 
               33 A,  33 B,  35 A,  35 B Lead part 
               36  Core wire 
               38  Insulating film 
               40 ,  42 ,  44 ,  46  Terminal electrode 
               50 ,  52 ,  54 ,  56  Terminal metal plate 
               60  Metal plate body 
               62  Locking tab 
               64  Joining tab 
               70 ,  72 ,  74 ,  76  Welded part 
               71  Peak point 
               73  Vertical line 
               75  Surface 
               80 ,  82 ,  84 ,  86  Foundation part 
               90 ,  92 ,  94 ,  96  Engagement part 
               100 ,  200  Terminal electrode 
               101 ,  201  Welded part 
               102 ,  202  Foundation part 
               103 ,  203  Conductive wire 
               104 ,  204  Metal plate 
               105 ,  205  Peak point 
               106 ,  206  Vertical line 
               107 ,  207  Surface 
               108 ,  208  Maximum diameter part 
               110  Exterior core 
               120  Circuit board 
               122  Electrode 
               124  Solder 
               500 ,  600 ,  700 ,  800  Coil component 
               900  Electronic device 
           
         
       
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     First, the constitutions as well as operations and effects of the invention under the present application for patent, are explained.  FIG. 1A  is a cross-sectional view of a terminal electrode  100  in a coil component according to the invention under the present application for patent, while  FIG. 1B  is a cross-sectional view of a terminal electrode  200  in a coil component representing a comparative example.  FIG. 1A  illustrates a cross-section passing through the peak point  105  where the height of the welded part  101  from the foundation part  102  becomes the highest.  FIG. 1B  illustrates a cross-section passing through the peak point  205  at which the height of the welded part  201  from the foundation part  202  becomes the highest. 
     The terminal electrode  100  in the coil component according to the invention under the present application for patent has: a foundation part  102  constituted by a metal plate  104 ; and a welded part  101  formed on the foundation part  102  by a part of the metal plate  104  being welded to a conductive wire  103 . The welded part  101  is joined to the foundation part  102  by an alloy layer formed between the welded part  101  and the foundation part  102 . The welded part  101  is formed by a part of the metal part  104  fusing to the conductive wire  103 , and therefore has a rounded shape resulting from rising of the fused portion. 
     Now, a vertical line  106  is defined, which passes through a peak point  105  at which the height of the welded part  101  from the foundation part  102  becomes the highest and which also crosses at right angles with the foundation part  102 . The welded part  101  is shaped in such a way that the distance from the vertical line  106  to the surface  107  of the welded part  101  as viewed in a direction parallel with the foundation part  102  (also describable as a direction parallel with the face of the foundation part  102  contacted by the welded part  101  and direction crossing at right angles with the vertical line  106 ), is longer at a point closer to the foundation part  102  when viewed at least in one direction from the vertical line  106 . In other words, between the peak point  105  and the foundation part  102 , the distance from the vertical line  106  to the surface  107  of the welded part  101  as viewed in a direction parallel with the foundation part  102 , is continuously longer from the peak point  105  toward the foundation part  102 , being shorter on the peak point  105  side and longer on the foundation part  102  side. This means that the distance from the vertical line  106  to the surface  107  of the welded part  101  as viewed in a direction parallel with the foundation part  102 , becomes the longest on the joining face of the welded part  101  with the foundation part  102 . Put it differently, among the faces of the welded part  101  running parallel with the foundation part  102 , the joining face of the welded part  101  with the foundation part  102  represents the maximum diameter part  108  of the welded part  101 . This way, the joining can be achieved without fail and the joining strength can be increased. 
     In contrast, with the terminal electrode  200  in the coil component representing the comparative example, the shape of its welded part  201  which is formed on a foundation part  202  constituted by a metal plate  204  and to which a conductive wire  203  is connected, is different from that of the welded part  101  representing the invention under the present application for patent. At the welded part  201 , the maximum diameter part  208  is positioned above the foundation part  202 . For this reason, the distance to the surface  207  of the welded part  201  from the vertical line  206  passing through the peak point  205  and crossing at right angles with the foundation part  202 , as viewed in a direction parallel with the foundation part  202 , becomes gradually longer from the peak point  205  toward the maximum diameter part  208  and then gradually shorter from the maximum diameter part  208  toward the foundation part  202 . When the welded part  201  has such shape, the height of the welded part  201  becomes higher. This makes it difficult to reduce the size of the coil component comprising the welded part  201 . 
     On the other hand, with the terminal electrode  100  in the coil component according to the invention under the present application for patent, the distance from the vertical line  106  to the surface  107  of the welded part  101  as viewed in a direction parallel with the foundation part  102 , is longer at a point closer to the foundation part  102  when viewed at least in one direction from the vertical line  106 . When the welded part  101  has such shape, the height of the welded part  101  becomes lower compared to the welded part  201  in the coil component representing the comparative example. This permits size reduction of the coil component comprising the welded part  101 . 
     The following explains embodiments of the invention under the present application for patent by referring to the drawings as deemed appropriate. Constitutional elements that are common in multiple drawings are denoted with the same reference symbols throughout the multiple drawings. It should be noted that, for the sake of explanation, the scale in which each drawing was written is not necessarily accurate. 
     First Embodiment 
     The coil component  500  pertaining to the first embodiment of the invention under the present application for patent is explained by referring to  FIGS. 2, 3A, 3B, 4A, 4B , and  5 .  FIG. 2  is a perspective view showing the coil component  500  pertaining to the first embodiment of the invention under the present application for patent.  FIG. 3A  is a view of the coil component  500  from the arrow F 1  side in  FIG. 2 , while  FIG. 3B  is a view of the coil component  500  from the arrow F 2  side in  FIG. 2 . It should be noted that, in  FIGS. 3A and 3B , the winding part  30  is partially not shown in order to illustrate the winding core  12  clearly.  FIG. 4A  is a cross-sectional view at the flange part  14 , while  FIG. 4B  is a cross-sectional view at the flange part  16 , of the coil component  500 .  FIG. 5  is a view of cross-section A-A of the terminal electrode  40  in  FIG. 3A . To be specific,  FIG. 5  is a view of a cross-section which is orthogonal to the surface of the flange part  14  on which the welded part  70  is provided and which also passes through the peak point  71  at which the height of the welded part  70  from the foundation part  80  becomes the highest and through the center of the conductive wire  32  (center of the lead part  33 A). 
     As shown in  FIG. 5 , the coil component  500  is such that, between the peak point  71  and the foundation part  80 , the distance to the surface  75  of the welded part  70  from the vertical line  73  passing through the peak point  71  and crossing at right angles with the foundation part  80 , as viewed in a direction parallel with the foundation part  80 , is continuously longer from the peak point  71  toward the foundation part  80 , being shorter on the peak point  71  side and longer on the foundation part  80  side. Having the welded part  70  of such dimensional relationships means the height of the peak point  71  of the welded part can be lowered. This permits size reduction of the coil component  500 . 
     The following explains in detail each part constituting the coil component  500 . The coil component  500  is described as a common-mode filter by way of example, but the present invention is not limited thereto. As shown in  FIGS. 2, 3A, 3B, 4A, 4B, and 5 , the coil component  500  comprises a drum core  10 , a winding part  30 , and terminal electrodes  40 ,  42 ,  44 ,  46 . The drum core  10  comprises a winding core  12 , a flange part  14  provided at one end part of the winding core  12  in the axial direction, and a flange part  16  provided at the other end part of the winding core  12  in the axial direction. The winding core  12  has a roughly rectangular shape in terms of cross-section shape, for example, but it may have a polygonal shape such as hexagon or octagon, etc., or it may also have a circular shape, oval shape, etc. The flanges  14 ,  16  each have a rectangular solid shape having concaved parts. The drum core  10  is formed by Ni—Zn ferrite material, for example, but it may be formed by other material. For instance, the drum core  10  may be formed by Mn—Zn ferrite material, Fe—Si—Cr, Fe—Si—Al, Fe—Si—Cr—Al, or other soft magnetic alloy material, Fe, Ni, or other magnetic metal material, amorphous magnetic metal material, or nanocrystal magnetic metal material. 
     The dimensions of the coil component  500  are 3.2 mm in length, 2.5 mm in width, and 2.5 mm in height, for example. Here, the length of the coil component  500  indicates the dimension in the axial direction (X direction in  FIG. 2 ), while its width indicates the dimension in the direction crossing at right angles with the X direction and running parallel with the mounting face (Y direction in  FIG. 2 ), and its height indicates the dimension in the direction crossing at right angles with the X direction and Y direction (Z direction in  FIG. 2 ), of the winding core  12  of the drum core  10 . The dimensions of the drum core  10  are 3.0 mm in length (dimension in the X direction in  FIG. 2 ), 2.5 mm in width (dimension in the Y direction in  FIG. 2 ), and 1.6 mm in height (dimension in the Z direction in  FIG. 2 ), for example. The winding core  12  of the drum core  10  has a width (dimension in the Y direction in  FIG. 2 ) of 1.6 mm and a height (dimension in the Z direction in  FIG. 2 ) of 0.8 mm, for example. 
     The winding part  30  comprises two conductive wires  32 ,  34 . The conductive wire  32  is wound around the winding core  12 , with one end electrically connected to the terminal electrode  40  and the other end electrically connected to the terminal electrode  46 . The conductive wire  34  is wound around the winding core  12 , with one end electrically connected to the terminal electrode  42  and the other end electrically connected to the terminal electrode  44 . The conductive wire  32  is wound around the winding core  12  over the conductive wire  34 . The conductive wires  32 ,  34  each have a construction of a core wire  36  made of copper whose peripheral face is covered with an insulating film  38  made of polyamide imide, for example. The core wire  36  may be formed by a metal other than copper; for example, it may be formed by silver, palladium, or silver-palladium alloy. The insulating film  38  may be formed by an insulating material other than polyamide imide; for example, it may be formed by polyester imide, polyurethane, or other resin material. The diameters of the conductive wires  32 ,  34  are 0.05 mm, for example. The conductive wires  32 ,  34  are wound around the winding core  12  by the same number of turns, respectively. 
     The flange part  14  has a bottom face  14 A, a top face  14 B, end faces  14 C,  14 D, and side faces  14 E,  14 F. The flange part  16  has a bottom face  16 A, a top face  16 B, end faces  16 C,  16 D, and side faces  16 E,  16 F. The bottom faces  14 A,  16 A, when the coil component  500  is mounted on a circuit board, will become faces opposing the circuit board. The side faces  14 F,  16 F are faces to which the winding core  12  is connected. 
     A concaved part  18  is formed on the end face  14 C, while a concaved part  20  is formed on the end face  14 D, of the flange part  14 . The concaved parts  18 ,  20  are formed at positions across the centers of the end faces  14 C,  14 D in the vertical direction. The concaved parts  18 ,  20  are formed in a manner connecting to the base portions via tapered faces from the end faces  14 C,  14 D, for example. The tapered faces and bases of the concaved parts  18 ,  20  are considered parts of the end faces  14 C,  14 D, respectively. The angles of the tapered faces of the end faces  14 C,  14 D are set as deemed appropriate according to the directions in which the conductive wires  32 ,  34  are led out, etc. Just like the concaved parts  18 ,  20  formed in the flange part  14 , a concaved part  22  is formed on the end face  16 C, while a concaved part  24  is formed on the end face  16 D, of the flange part  16 . The thicknesses of the flange parts  14 ,  16  are 0.6 mm, for example. The depths of the concaved parts  18 ,  20 ,  22 ,  24  are 0.5 mm, for example, while the widths of their base parts are 0.7 mm, for example. 
     The terminal electrodes  40 ,  42  are provided on the flange part  14 . The terminal electrodes  44 ,  46  are provided on the flange part  16 . The terminal electrode  40  is constituted by a terminal metal plate  50 , while the terminal electrode  42  is constituted by a terminal metal plate  52 . The terminal electrode  44  is constituted by a terminal metal plate  54 , while the terminal electrode  46  is constituted by a terminal metal plate  56 . The terminal metal plates  50 ,  52 ,  54 ,  56  are Sn-plated phosphor bronze plates, for example, but brass plates, tough pitch copper plates, or plates of other metals may be used. 
     The terminal metal plate  50  is attached to the flange part  14  in a manner extending from the bottom face  14 A, via the side face  14 E, to the top face  14 B, while also extending to the concaved part  18  provided on the end face  14 C, of the flange part  14 . The terminal metal plate  52  is attached to the flange part  14  in a manner extending from the bottom face  14 A, via the side face  14 E, to the top face  14 B, while also extending to the concaved part  20  provided on the end face  14 D, of the flange part  14 . Similarly, the terminal metal plate  54  is attached to the flange part  16  in a manner extending from the bottom face  16 A, via the side face  16 E, to the top face  16 B, while also extending to the concaved part  24  provided on the end face  16 D, of the flange part  16 . The terminal metal plate  56  is attached to the flange part  16  in a manner extending from the bottom face  16 A, via the side face  16 E, to the top face  16 B, while also extending to the concaved part  22  provided on the end face  16 C, of the flange part  16 . 
       FIG. 6  is a drawing for explaining the terminal metal plate  50  of the coil component  500 . It should be noted that, since the terminal metal plates  52 ,  54 ,  56  have the same construction as the terminal metal plate  50 , only the terminal metal plate  50  is explained and the terminal metal plates  52 ,  54 ,  56  are not explained. 
     As shown in  FIG. 6 , the terminal metal plate  50  comprises a metal plate body  60 , a locking tab  62  extending from the metal plate body  60 , and a joining tab  64  placed at a distance from the locking tab  62  and extending from the metal plate body  60 . The metal plate body  60  is attached to the surface of the flange part  14  with the side on one end pressed against the bottom face  14 A, and the side on the other end pressed against the top face  14 B, of the flange part  14 . The locking tab  62  and joining tab  64  are placed inside the concaved part  18  provided on the end face  14 C. The locking tab  62  is provided for the purpose of locking the conductive wire  32  by sandwiching it with the metal plate body  60 . The joining tab  64 , which is joined to the conductive wire  32  by means of welding, is provided for the purpose of electrically connecting the conductive wire  32  with the terminal metal plate  50 . 
     As shown in  FIGS. 2, 3A, 3B, 4A, 4B and 5 , one end part of the conductive wire  32  is joined to the joining tab  64  of the terminal metal plate  50  by means of welding. As a result, the fused portion rises and a rounded, dome-shaped welded part  70  is formed, and by this welded part  70 , a lead part  33 A constituted by the conductive wire  32  being led out from the winding part  30  is electrically connected to the terminal electrode  40 . The other end part of the conductive wire  32  is joined to the joining tab  64  of the terminal metal plate  56  by means of welding. As a result, the fused portion rises and a rounded, dome-shaped welded part  76  is formed, and by this welded part  76 , a lead part  33 B constituted by the conductive wire  32  being led out from the winding part  30  is electrically connected to the terminal electrode  46 . Similarly, one end part of the conductive wire  34  is joined to the joining tab  64  of the terminal metal plate  52  by means of welding and thus a rounded, dome-shaped welded part  72  is formed, and by this welded part  72 , a lead part  35 A constituted by the conductive wire  34  being led out from the winding part  30  is electrically connected to the terminal electrode  42 . The other end part of the conductive wire  34  is joined to the joining tab  64  of the terminal metal plate  54  by means of welding and thus a rounded, dome-shaped welded part  74  is formed, and by this welded part  74 , a lead part  35 B constituted by the conductive wire  34  being led out from the winding part  30  is electrically connected to the terminal electrode  44 . The welded parts  70 ,  72 ,  74 ,  76  are formed by means of laser welding, arc welding, or the like. 
     Of the conductive wire  32 , the lead part  33 A positioned between the winding part  30  and the welded part  70  is locked in a manner being sandwiched between an engagement part  90  constituted by the locking tab  62  of the terminal metal plate  50  that has been bent, and a foundation part  80  constituted by the metal plate body  60  of the terminal metal plate  50 . Also, of the conductive wire  32 , the lead part  33 B positioned between the winding part  30  and the welded part  76  is locked in a manner being sandwiched between an engagement part  96  constituted by the locking tab  62  of the terminal metal plate  56  that has been bent, and a foundation part  86  constituted by the metal plate body  60  of the terminal metal plate  56 . 
     Similarly, of the conductive wire  34 , the lead part  35 A positioned between the winding part  30  and the welded part  72  is locked in a manner being sandwiched between an engagement part  92  constituted by the locking tab  62  of the terminal metal plate  52  that has been bent, and a foundation part  82  constituted by the metal plate body  60  of the terminal metal plate  52 . Also, of the conductive wire  34 , the lead part  35 B positioned between the winding part  30  and the welded part  74  is locked in a manner being sandwiched between an engagement part  94  constituted by the locking tab  62  of the terminal metal plate  54  that has been bent, and a foundation part  84  constituted by the metal plate body  60  of the terminal metal plate  54 . 
     The conductive wire  32  projects from the welded part  70  by a portion of a prescribed length from a tip face  32 A which is a cross-section at the tip on the lead part  33 A side, and also projects from the welded part  76  by a portion of a prescribed length from a tip face  32 B which is a cross-section at the tip on the lead part  33 B side. Similarly, the conductive wire  34  projects from the welded part  72  by a portion of a prescribed length from a tip face  34 A which is a cross-section at the tip on the lead part  35 A side, and also projects from the welded part  74  by a portion of a prescribed length from a tip face  34 B which is a cross-section at the tip on the lead part  35 B side. 
     The welded part  70  is formed on the foundation part  80 . Similarly, the welded parts  72 ,  74 ,  76  are formed on the foundation parts  82 ,  84 ,  86 . The welded parts  70 ,  72 ,  74 ,  76  are joined to the foundation parts  80 ,  82 ,  84 ,  86  via alloy layers. Now, a vertical line which passes through the peak point  71  at which the height of the welded part  70  from the foundation part  80  becomes the highest, and which also crosses at right angles with the foundation part  80 , is defined as a vertical line  73 . The welded part  70  is shaped in such a way that the distance from the vertical line  73  to the surface  75  of the welded part  70  as viewed in a direction parallel with the foundation part  80 , is longer at a point closer to the foundation part  80  when viewed at least in one direction from the vertical line  73 . The distance from the vertical line  73  to the surface  75  of the welded part  70  as viewed in a direction parallel with the foundation part  80 , is continuously longer from the peak point  71  toward the foundation part  80 . The welded parts  72 ,  74 ,  76  have the same shape. 
     [Manufacturing Method] 
     Next, a method for manufacturing the coil component  500  is explained. First, a drum core  10  is formed. For example, a binder is mixed into a Ni—Zn ferrite material and the mixed material is compression-molded using a molding die, to obtain a drum-shaped molded body. If necessary, this molded body may be deburred. This molded body is sintered at a prescribed sintering temperature to obtain a drum core  10  having a winding core  12  and flange parts  14 ,  16 . Next, terminal metal plates  50 ,  52  are bent, clinched or otherwise installed and placed on the flange part  14  of the drum core  10 . Terminal metal plates  54 ,  56  are bent, clinched or otherwise installed and placed on the flange part  16  of the drum core  10 . A conductive wire  34  is wound by the necessary number of times around the outer peripheral face of the winding core  12  of the drum core  10 , and then a conductive wire  32  is wound by the necessary number of times around the winding core  12  on the outside of the conductive wire  34 , to form a winding part  30 . The conductive wires  32 ,  34  are wound by the same number of times. The end parts of the conductive wire  32  are led out onto the terminal metal plates  50 ,  56  and joined for the purpose of electrically connecting the conductive wire  32  and the terminal metal plates  50 ,  56 . Similarly, the end parts of the conductive wire  34  are led out onto the terminal metal plates  52 ,  54  and joined for the purpose of electrically connecting the conductive wire  34  and the terminal metal plates  52 ,  54 . 
     The method for manufacturing the coil component  500  is explained in detail by referring to  FIGS. 7A to 8B .  FIGS. 7A to 8B  are drawings for explaining the method for manufacturing the coil component  500 . It should be noted that, while the vicinity of the terminal metal plate  50  is shown and explained in  FIGS. 7A to 8B , the vicinities of the terminal metal plates  52 ,  54 ,  56  are the same and therefore not explained here. 
     As shown in  FIG. 7A , the terminal metal plate  50  having a metal plate body  60 , as well as a locking tab  62  and a joining tab  64  each extending from the metal plate body  60 , is bent or otherwise placed on the flange part  14  of the drum core  10 . The conductive wires  32 ,  34  are wound around the winding core  12  of the drum core  10 , to form a winding part  30 . One end part side of the conductive wire  32  is led out onto the metal plate body  60  of the terminal metal plate  50  using a clamp or other jig  130 . Next, an insulating film  38  is removed from the portion of the conductive wire  32  sandwiched between the metal plate body  60  and the joining tab  64 , to expose a core wire  36 . The removal of the insulating film  38  may be performed by irradiating laser beam, for example. 
     As shown in  FIG. 7B , both the locking tab  62  and joining tab  64  are bent at normal temperature, and a lead part  33 A constituted by the conductive wire  32  being led out from the winding part  30  is sandwiched between the metal plate body  60  and the locking tab  62  and joining tab  64  and fixed in place. 
     As shown in  FIG. 8A , the conductive wire  32  is cut to create a state where the tip part of the conductive wire  32  is positioned on the outer side of the joining tab  64 . For the cutting of the conductive wire  32 , any generally performed method may be employed. The conductive wire  32  may be cut by press-cutting using the jig used for bending the terminal metal plate  50  and the locking tab  62  and joining tab  64 , for example. In this case, the manufacturing steps can be reduced because the bending of the locking tab  62  and joining tab  64 , and the cutting of the conductive wire  32 , can be performed at the same time. The position at which the conductive wire  32  is cut may be on the metal plate body  60 . Press-cutting it on the metal plate body  60  allows for prevention of damage to the magnetic body or, conversely, breakage, etc., of the cutting blade. Also, any cutting blade used for press-cutting can produce a cut only through a movement in one direction, which reduces any space limitation on its placement. As a result, the cutting position can be set inside the external dimensions of the coil component  500  to prevent the tip part of the conductive wire  32  from protruding out of the external dimensions. This, in turn, prevents the tip part of the conductive wire  32  from interfering with other components, for example. 
     As shown in  FIG. 8B , the joining tab  64  is welded with the conductive wire  32  in a state where the tip part of the conductive wire  32  is positioned on the outer side of the joining tab  64 , to join the joining tab  64  with the conductive wire  32 . As a result, a welded part  70  is formed, causing the lead part  33 A constituted by the conductive wire  32  being led out from the winding part  30  at the welded part  70 , to be electrically connected with the terminal metal plate  50 . For the welding of the joining tab  64  with the conductive wire  32 , laser welding may be used, for example; however, arc welding or other welding method may also be used. By irradiating laser beam onto the joining tab  64  and thus fusing the joining tab  64 , the fused portion rises and a rounded, dome-shaped welded part  70  is formed. Because the joining tab  64  is joined with the conductive wire  32  in a state where the tip part of the conductive wire  32  is positioned on the outer side of the joining tab  64 , the conductive wire  32  projects from the welded part  70  by a portion of a prescribed length from the tip face  32 A. 
     Now, when laser beam is irradiated onto the joining tab  64  to weld the joining tab  64  with the conductive wire  32 , the power of laser beam, irradiating position, beam diameter, etc., are adjusted to achieve a temperature at which the joining tab  64  will fuse but the metal plate body  60  will not fuse. For example, the power of laser beam, irradiating position, beam diameter, etc., are adjusted so that the joining tab  64  will reach 900° C. or above and fuse, while the metal plate body  60  will reach only 500° C. or so and not fuse. By controlling the temperature of the metal plate body  60 , the degree to which the fused portion, where the joining tab  64  has fused, wets, and spreads over the metal plate body  60  can be controlled. The higher the temperature of the metal plate body  60 , the easier it becomes for the fused portion to wet and spread, and consequently the height of the welded part  70  becomes lower. Conversely, the lower the temperature of the metal plate body  60 , the more difficult it becomes for the fused portion to wet and spread, and consequently the height of the welded part  70  becomes higher. As described above, controlling the irradiation of laser beam and thereby controlling the temperature of the metal plate body  60  to an appropriate temperature causes a welded part  70  to form whose shape is such that the distance from the vertical line  73  to the surface  75  of the welded part  70  as viewed in a direction parallel with the foundation part  80  becomes longer at a point closer to the foundation part  80 , as shown in  FIG. 5 . Thereafter, the tip part of the conductive wire  32  that projects from the welded part  70  may be partially cut to shorten the length by which the tip part of the conductive wire  32  projects from the welded part  70 , so that the tip part of the conductive wire  32  projects from the welded part  70  while still contained within the range overlapping with the drum core  10 . 
     It should be noted that, while the manufacturing method in this embodiment illustrated an example where the insulating film  38  was removed from the portion of the conductive wire  32  corresponding to the joining tab  64 , the step to remove the insulating film  38  may not be necessary depending on the material of the insulating film  38 . 
     As described above, the coil component  500  is such that the distance from the vertical line  73  to the surface  75  of the welded part  70  as viewed in a direction parallel with the foundation part  80  becomes longer at a point closer to the foundation part  80  when viewed at least in one direction from the vertical line  73 . As a result, the height of the welded part  70  becomes lower. If the welded part  70  is protruding to the outside of the outline of the coil component  500 , the welded part  70  may contact external members and consequently separate from the foundation part  80 , causing the electrical connection between the conductive wire  32  and the terminal electrode  40  to be lost. This is why the welded part  70  is contained in the concaved part  18  provided on the flange part  14 . When the height of the welded part  70  is lower, the depth of the concaved part  18  can be made shallow. For example, assume that the concaved part  18  must be formed deep; in this case, it is difficult to make the drum core  10  small when the strength of the drum core  10 , etc., are considered. With the coil component  500 , however, the concaved part  18  can be made shallow and therefore the drum core  10  can be made small. This allows for size reduction of the coil component  500 . It should be noted that, even when the flange part has no concaved part formed on it for accommodating the welded part, size reduction of the coil component is still possible because the height of the welded part is lower. 
     Also, the fact that the distance from the vertical line  73  to the surface  75  of the welded part  70  as viewed in a direction parallel with the foundation part  80  becomes longer at a point closer to the foundation part  80 , facilitates the emission, toward the upper side of the foundation part  80 , of the radiation heat energy emitted from the fused portion when the joining tab  64  fuses and the welded part  70  is formed, and also of the scattering light from the irradiation of laser beam to the joining tab  64 . As a result, the effects of the radiation heat energy and scattering light of laser beam on the foundation part  80  and winding part  30  can be reduced. Since the emission of the radiation heat energy and scattering light of laser beam toward the winding part  30  is prevented, the welded part  70  can be placed near the winding part  30 . This point, too, allows for size reduction of the coil component  500 . To prevent the emission of the radiation heat energy and scattering light of laser beam toward the foundation part  80  and winding part  30 , the angle θ formed between the portion of the foundation part  80  joined by the welded part  70  and the surface of the welded part  70  (refer to  FIG. 5 ), is preferably 80° or smaller, or more preferably 70° or smaller, or yet more preferably 60° or smaller. 
     As shown in  FIG. 5 , the maximum distance L from the vertical line  73  to the surface  75  of the welded part  70  in parallel with the foundation part  80  as viewed in the direction of the lead part  33 A, is preferably longer than the distance H from the foundation part  80  to the peak point  71  of the welded part  70 . In this case, the welded part  70  is shaped longer in a direction parallel with the foundation part  80 , and also shaped in such a way that the height from the foundation part  80  is lower. This allows for lowering of the height of the welded part  70 , and consequently size reduction of the coil component  500 . From the viewpoint of size reduction of the coil component  500 , the maximum distance L from the vertical line  73  to the surface  75  of the welded part  70  in parallel with the foundation part  80  as viewed in the direction of the lead part  33 A, is preferably 1.2 times or greater than, or more preferably 1.5 times or greater than, or yet more preferably two times or greater than, the distance H from the foundation part  80  to the peak point  71  of the welded part  70 . 
       FIG. 9A  is a side view of the welded part  70 , while  FIGS. 9B to 9D  are views of cross-sections A-A to C-C, respectively, in  FIG. 9A . As shown in  FIGS. 9A to 9D , the welded part  70  is such that, when cut in a direction vertical to the vertical line  73 , the area of its cross-section is smaller on the peak point  71  side and larger on the foundation part  80  side. The cross-section area of the welded part  70 , when cut in a direction orthogonal to the vertical line  73 , is continuously larger from the peak point  71  toward the foundation part  80 . That is to say, preferably the welded part  70  has a larger area for its cross-section orthogonal to the vertical line  73 , when the cross-section is closer to the foundation part  80 . Such construction results in a lower height of the welded part  70 , which allows for size reduction of the coil component  500 . 
     As shown in  FIG. 5 , preferably the welded part  70  has a dome shape, and the angle θ formed between the portion of the foundation part  80  contacted by the welded part  70  and the surface  75  of the welded part  70  is preferably 60° or smaller. This way, the height of the welded part  70  becomes lower, to allow for size reduction of the coil component  500 . Another point is that, even when an external force is applied laterally to the welded part  70 , separation of the welded part  70  from the foundation part  80  due to this external force is prevented. From the viewpoints of size reduction of the coil component  500  and prevention of separation of the welded part  70 , the angle θ formed between the portion of the foundation part  80  contacted by the welded part  70  and the surface  75  of the welded part  70  is preferably 55° or smaller, or more preferably 50° or smaller, or yet more preferably 45° or smaller. 
     With the coil component  500 , the terminal electrode  40  comprises an engagement part  90  that locks the lead part  33 A by sandwiching it with the foundation part  80 . This can prevent the position of the conductive wire  32  from moving relative to the joining tab  64  before and after the welding of the conductive wire  32  with the joining tab  64 . 
     Second Embodiment 
     The coil component  600  pertaining to the second embodiment is explained. The coil component  600  pertaining to the second embodiment is constitutionally identical to the coil component  500  pertaining to the first embodiment, except for the terminal electrode  40 . In other words,  FIGS. 2, 3A, 3B, 4A, and 4B  illustrating the coil component  500  pertaining to the first embodiment, illustrate the coil component  600  pertaining to the second embodiment, except for the terminal electrode  40 . This means that, for each part constituting the coil component  600  pertaining to the second embodiment, except for the terminal electrode  40 , the coil component  500  pertaining to the first embodiment can be applied. Also, for the method for manufacturing the coil component  600  pertaining to the second embodiment, what is described for the coil component  500  pertaining to the first embodiment can be applied. 
       FIG. 10  is a cross-sectional view of the terminal electrode  40  in the coil component  600  pertaining to the second embodiment of the invention under the present application for patent, and a drawing showing cross-section A-A of the terminal electrode  40  in  FIG. 3A . To be specific,  FIG. 10  is a view of a cross-section which is orthogonal to the surface of the flange part  14  on which the welded part  70  is provided and which also passes through the peak point  71  at which the height of the welded part  70  from the foundation part  80  becomes the highest and through the center of the conductive wire  32  (center of the lead part  33 A). In the first embodiment, the welded part  70  was formed on a flat, planar portion of the foundation part  80 , as shown in  FIG. 5 ; in the second embodiment, on the other hand, the welded part  70  is formed on the foundation part  80  in a manner covering the curved portion of the foundation part  80 , as shown in  FIG. 10 . In this case, the distance from the vertical line  73  to the surface  75  of the welded part  70  as viewed in a direction parallel with the foundation part  80  only needs to be longer at a point closer to the foundation part  80  when viewed at least in the direction of the lead part  33 A from the vertical line  73 . 
     When the welded part  70  is provided in a manner covering the curved portion of the foundation part  80 , as shown in  FIG. 10 , the welded part  70  protrudes to the outside of the foundation part  80 . When the welded part  70  protrudes out from the foundation part  80 , the welded part  70  becomes prone to contact with external members. As a result, preferably the welded part  70  is formed on the foundation part  80  in a manner contained within the range where the surface of the flange part  14  on which the welded part  70  is provided overlaps the foundation part  80  in plan view, as shown in  FIG. 3A . This way, the welded part  70  can be prevented from contacting external members. It also leads to size reduction of the coil component  600 . 
     While the aforementioned first and second embodiments illustrated examples where the coil component was a common-mode filter, it may be a coil component for single line or any other coil component.  FIG. 11  is a drawing of a coil component  700  for single line. As shown in  FIG. 11 , only the conductive wire  32  is wound, and the conductive wire  34  is not wound, around the winding core  12  of the drum core  10 . On the flange part  14 , only the terminal electrode  40  is provided and the terminal electrode  42  is not provided, while on the flange part  16 , only the terminal electrode  46  is provided and the terminal electrode  44  is not provided. It should be noted that, while the engagement parts  90 ,  96  are not provided in  FIG. 11 , the engagement parts  90 ,  96  may be provided.  FIG. 12  is a perspective view of a coil component  800  having an exterior core provided on the outer periphery of a drum core. As shown in  FIG. 12 , the exterior core  110  is provided on the outer periphery of the drum core  10 . Only the conductive wire  32  is wound, and the conductive wire  34  is not wound, around the winding core  12  of the drum core  10 . The external electrodes  40 ,  46  are attached to the exterior core  110 . The lead parts  33 A,  33 B constituted by the conductive wire  32  are led out onto the terminal electrodes  40 ,  46  placed on the exterior core  110 . 
     As explained above, the substrate body may be a drum core  10  having flange parts  14 ,  16  provided at both ends of a winding core  12 , or it may be constituted by a drum core  10  and an exterior core  110  placed on the outer periphery of the drum core  10 . When it is constituted by a drum core  10  and an exterior core  110 , terminal electrodes  40 ,  46  may be provided on the exterior core  110 . Also, the substrate body may be other than a drum core  10  or what is constituted by a drum core  10  and an exterior core  110 ; for example, it may be a core (T-core) having a flange part provided only at one end part of a winding core, or other than a core. 
       FIG. 13  is a drawing showing an electronic device  900  comprising the coil component  500  pertaining to the first embodiment of the invention under the present application for patent. As shown in  FIG. 13 , the electronic device  900  comprises a circuit board  120  and the coil component  500  mounted on the circuit board  120 . The coil component  500  is mounted on the circuit board  120  when its terminal electrodes  40 ,  42 ,  44 ,  46  (only the terminal electrodes  40 ,  46  are shown in  FIG. 13 ) are joined to an electrode  122  on the circuit board  120  by a solder  124 . 
     The electronic device  900  is such that the coil component  500  is mounted on the circuit board  120 . This way, an electronic device  900  having a coil component  500  of reduced size can be obtained. It should be noted that, while the coil component  500  in the first embodiment was mounted on the circuit board  120  in the illustrated example of the electronic device  900 , the coil component  600  in the second embodiment may be mounted, or the coil component  700 , coil component  800 , or any of various modes of the coil component proposed by the invention under the present application for patent, other than the coil component  500 , may be mounted. 
     The foregoing described the embodiments of the invention under the present application for patent in detail; it should be noted, however, that the invention under the present application for patent is not limited to these specific embodiments, and various modifications and changes may be added to the extent that doing so does not deviate from the key points of the invention under the present application for patent as described in “What Is Claimed Is.”