Patent Publication Number: US-11640872-B2

Title: Method for manufacturing coil component

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Japanese Patent Application No. 2018-248306, filed Dec. 28, 2018, 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 method for manufacturing a coil component. 
     Description of the Related Art 
     Coil components, each comprising multiple conductive wires wound around a winding core that constitutes a drum core, are known. For example, it is known that, by winding multiple conductive wires around a winding core in such a way that they are lined up in a single layer from one to the other of a pair of flange parts connected to both ends of the winding core, a wide variety of inductance values can be obtained (refer to Patent Literature 1, for example). Also, the following is known: connect multiple conductive wires to an external electrode part of a core through a wire guard or winding nozzle, turn the winding nozzle in a forward direction by a specified number of times to form twisted conductive wire parts above and below the winding nozzle, and turn the core to allow the twisted conductive wire part below the winding nozzle to be wound around the core; subsequently, turn the winding nozzle in the reverse direction to release the twisting of the twisted part above the winding nozzle, while forming a twisted part below the winding nozzle at the same time, and then turn the core to allow the twisted conductive wire part below the winding nozzle to be wound around the core (refer to Patent Literature 2, for example). Also, common mode choke coils, each having a first conductive wire and a second conductive wire that are wound around a winding core by the same number of turns, are known (refer to Patent Literature 3, for example). 
     Background Art Literatures 
     
         
         
           
             [Patent Literature 1] Japanese Patent Laid-open No. 2003-124031 
             [Patent Literature 2] Japanese Patent Laid-open No. 2010-147132 
             [Patent Literature 3] Japanese Patent Laid-open No. 2017-112156 
           
         
       
    
     SUMMARY 
     As electronic devices become increasingly smaller, reduction of coil component size is being required. When multiple conductive wires are to be wound around a winding core, desirably they are wound by the same number of turns from the viewpoints of obtaining a desired inductance, or the like. In this case, the region in which the conductive wires are wound may become larger and the drum core size may increase as a result, making it difficult to address the requirement to reduce the coil component size. 
     The present invention was made in light of the aforementioned problem, and its object is to reduce the coil component size. 
     The present invention is a method for manufacturing a coil component, comprising: a step to prepare a drum core that includes a winding core, a first flange part provided on one end of the winding core in the axial direction, and a second flange part provided on the other end of the winding core in the axial direction; a first winding step where a first conductive wire, being a round wire, is wound around the winding core by a multiple number of turns in a single layer, from the first flange part toward the second flange part, in such a way that adjacent winding segments of the first conductive wire are contacting each other; and a second winding step where a second conductive wire, being a round wire, is wound around the winding core on an outer periphery of the first conductive wire by the same number of turns as in the first winding step in a single layer, from the first flange part toward the second flange part, in such a way that adjacent winding segments of the second conductive wire are contacting each other; wherein, in the second winding step, the second conductive wire is wound around the winding core in such a way that the center of the axial-direction cross-section of the second conductive wire at the second proximate winding segment which is the winding segment at the start of winding closest to the first flange part, is positioned closer to the first flange part side in the axial direction than is the center of the axial-direction cross-section of the first conductive wire at the first proximate winding segment which is the winding segment at the start of winding closest to the first flange part in the first winding step, and that the spacing in the axial direction, between the center of the cross-section at the first proximate winding segment and the center of the cross-section at the second proximate winding segment, becomes smaller than the equivalent radius of the first conductive wire on the cross-section. In some embodiments, the axial-direction cross-section is typically substantially the same as a radial cross-section where the winding direction is typically substantially perpendicular to the axial direction, wherein the radial cross-section and the axial-direction cross-section may be used interchangeably. 
     In the aforementioned constitution, it may be constituted in such a way that: the step to prepare a drum core comprises having the winding core have a concaved part positioned away from the first flange part and concaved in a direction crossing the axial direction; the first winding step comprises arranging the first proximate winding segment to fit in the concaved part; and the second winding step comprises arranging the second proximate winding segment to contact the first flange part. 
     In the aforementioned constitution, it may be constituted in such a way that: the step to prepare a drum core comprises having the winding core have a projecting part contacting the first flange part and projecting in a direction crossing the axial direction; the first winding step comprises arranging the first proximate winding segment to contact the side face, which crosses the axial direction, of the projecting part; and the second winding step comprises arranging the second proximate winding segment to contact the first flange part. 
     In the aforementioned constitution, it may be constituted in such a way that: the step to prepare a drum core comprises having the winding core have a concaved part that includes a face sloped (inclined) so that the diameter of the winding core decreases for points further away from the first flange part; the first winding step comprises arranging the first proximate winding segment to fit in the concaved part; and the second winding step comprises arranging the second proximate winding segment to contact the first flange part. 
     In the aforementioned constitution, it may be constituted in such a way that: the step to prepare a drum core comprises having the interior face, to which the winding core is connected, of the first flange part have a sloped (inclined) shape so that the thickness of the first flange part in the axial direction increases for points closer to the winding core; the first winding step comprises arranging the first proximate winding segment to contact the interior face of the first flange part; and the second winding step comprises arranging the second proximate turned winding segment to contact the interior face of the first flange part. 
     In the aforementioned constitution, it may be constituted in such a way that: a step to form a spacer part in contact with the first flange part around the winding core is provided before the first winding step; a step to remove the spacer part is provided after the first step and before the second winding step; the first winding step comprises arranging the first proximate winding segment to contact the side face, which crosses the axial direction, of the spacer part that has been formed in contact with the first flange part around the winding core; and the second winding step comprises arranging the second proximate winding segment to contact the first flange part after the spacer part has been removed. 
     According to the present invention, the coil component size can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a plan view,  FIG.  1 B  is a plan view seen from direction A in FIG. A, and  FIG.  1    C is a plan view seen from direction B in  FIG.  1 A , of the coil component pertaining to Example 1. 
         FIG.  2 A  is a cross-sectional view of the coil component pertaining to Example 1, while  FIG.  2    B is an enlarged view of region A in  FIG.  2 A . 
         FIGS.  3 A to  3 C  are cross-sectional views illustrating how the coil component pertaining to Example 1 is manufactured. 
         FIGS.  4 A to  4 C  are cross-sectional views illustrating how the coil component pertaining to Comparative Example 1 is manufactured. 
         FIGS.  5 A to  5 C  are cross-sectional views illustrating how the coil component pertaining to Example 2 is manufactured. 
         FIGS.  6 A to  6 C  are cross-sectional views illustrating how the coil component pertaining to Example 3 is manufactured. 
         FIGS.  7 A to  7 C  are cross-sectional views illustrating how the coil component pertaining to Example 4 is manufactured. 
         FIGS.  8 A to  8 C  are cross-sectional views illustrating how the coil component pertaining to Example 5 is manufactured. 
         FIG.  9 A  is a plan view, while  FIG.  9 B  is a plan view seen from direction A in  FIG.  9 A , of a coil component for single line. 
     
    
    
     DESCRIPTION OF THE SYMBOLS 
     
         
         
           
               10  Drum core 
               12 ,  12   a ,  12   b ,  12   c  Winding core 
               14 ,  14   a  Flange part 
               16 ,  16   a  Flange part 
               20 ,  30  Connection face 
               22 ,  32  Mounting face 
               24 ,  34  Interior face 
               26 ,  36  Exterior face 
               40  Concaved part 
               42  Projecting part 
               44  Concaved part 
               46  Spacer part 
               50  Conductive wire 
               52  Proximate winding segment 
               54  Center 
               60  Conductive wire 
               62  Proximate winding segment 
               64  Center 
               66  Last winding segment 
               70   a  to  70   d  Terminal electrode 
               500 ,  600  Coil component 
           
         
       
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Examples of the present invention are explained below by referring to the drawings. 
     Example 1 
       FIG.  1 A  is a plan view,  FIG.  1 B  is a plan view seen from direction A in FIG. A, and  FIG.  1 C  is a plan view seen from direction B in  FIG.  1 A , of the coil component pertaining to Example 1. It should be noted that, in  FIG.  1 A , the illustration of the windings of the conductive wires  50 ,  60  is simplified for the sake of clarity of figures. Also, in  FIGS.  1 A to  1 C , the conductive wire  50  and terminal electrodes  70   a  to  70   d  are hatched for the sake of clarity of figures.  FIG.  2 A  is a cross-sectional view of the coil component pertaining to Example 1, while  FIG.  2 B  is an enlarged view of region A in  FIG.  2 A . It should be noted that, in  FIG.  2    A, the terminal electrodes  70   a  to  70   d  are not illustrated. As shown in  FIGS.  1 A  to  1 C,  2 A, and  2 B, the coil component  500  in Example 1 is a common mode choke coil comprising a drum core  10 , conductive wires  50 ,  60 , and terminal electrodes  70   a  to  70   d.    
     The drum core  10  comprises a winding core  12 , a flange part  14  provided at one end of the winding core  12  in the axial direction, and a flange part  16  provided at the other end of the winding core  12  in the axial direction. The external dimensions of the drum core  10  are 3.2 mm in length dimension, 2.5 mm in width dimension, and 2.0 mm in height dimension, in one example. The flange parts  14 ,  16  are shaped as a rectangular solid, for example. The thickness dimensions of the flange parts  14 ,  16  are approx. 0.2 mm to 0.4 mm, for example. The winding core  12  is shaped as a circular cylinder having a concaved part  40 , for example. The length dimension of the winding core  12  is approx. 2.4 mm to 2.8 mm, for example. 
     The flange part  14  has a connection face  20 , a mounting face  22  on the side of the flange part  14  opposite to the connection face  20 , an interior face  24  to which the winding core  12  is connected, and an exterior face  26  on the side of the flange part  14  opposite to the interior face  24 . The flange part  16  has a connection face  30 , a mounting face  32  on the side of the flange part  16  opposite to the connection face  30 , an interior face  34  to which the winding core  12  is connected, and an exterior face  36  on the side of the flange part  16  opposite to the interior face  34 . The winding core  12  connects to the interior face  24  of the flange part  14  and the interior face  34  of the flange part  16  in such a way that the center axis of the winding core  12  roughly corresponds to the center of the interior face  24  of the flange part  14  and that of the interior face  34  of the flange part  16 . 
     The winding core  12  has a concaved part  40  formed on the flange part  14  side, which is concaved in a direction crossing (such as a direction crossing at right angles) the axial direction of the winding core  12 . The concaved part  40  is formed in a manner going all around the winding core  12 , for example. The concaved part  40  is away from the flange part  14  and does not contact the flange part  14 . The spacing X 1  between the concaved part  40  and the flange part  14  is smaller than the radius of the conductive wire  60 , for example. The drum core  10  is formed in such a way that it contains a magnetic material. For example, the drum core  10  is formed in such a way that it contains Ni—Zn, Mn—Zn, or other 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 conductive wire  50  is wound around the winding core  12  in a single layer. The conductive wire  50  is wound by a multiple number of turns, with adjacent winding segments contacting each other. The conductive wire  50  is wound around the winding core  12  in such a way that its proximate winding segment  52  wound closest to the flange part  14  is fitted in the concaved part  40 . The conductive wire  60  is wound around the winding core  12  on the exterior side of the conductive wire  50  in a single layer. The conductive wire  60  is wound by a multiple number of turns, with adjacent winding segments contacting each other. The number of turns by which the conductive wire  60  is wound around the winding core  12  is the same as the number of turns by which the conductive wire  50  is wound around the winding core  12 . The conductive wire  60  is wound in such a way that its winding segments, and corresponding winding segments of the conductive wire  50 , are contacting each other by 0.5 turns or more. In other words, the conductive wire  60  is wound in such a way that its winding segments are in contact, at least partially, with those of the conductive wire  50  in turns representing the same numbers of turns. The conductive wire  50 , and the conductive wire  60 , are positioned away from each other at the winding segments representing different numbers of turns. 
     The conductive wire  60  is wound around the winding core  12  in such a way that the center  64  of the cross-section at the proximate winding segment  62  wound closest to the flange part  14 , is positioned closer to the flange part  14  side in the axial direction than is the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 . The proximate winding segment  62  of the conductive wire  60  is contacting the flange part  14 . The spacing X 2  in the axial direction, between the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50  and the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60 , is smaller than the radius of the conductive wire  50 . Also, the angle θ formed by a line segment connecting the centers of adjacent winding segments of the conductive wire  50 , and a line segment connecting the center of the winding segment on the flange part  14  side of the adjacent winding segments, and the center of the winding segment of the conductive wire  60  representing the same turn as the aforementioned winding segment, is greater than 90° but smaller than 120°. The formed angle θ may be 95° or greater but no greater than 115°, or 100° or greater but no greater than 110°. It should be noted that, if the center of the winding segment (referred to as the “second winding segment”) of the conductive wire  60  representing the same turn as the winding segment on the flange part  14  side (referred to as “first winding segment”) of the adjacent winding segment of the conductive wire  50 , is positioned closer to the flange part  16  side in the axial direction of the winding core  12  than is the center of the first winding segment, then the formed angle θ becomes smaller than 90°. 
     The conductive wires  50 ,  60  are round wires whose cross-section has a circular shape. The diameters of the conductive wires  50 ,  60  are approx. 0.03 mm to 0.5 mm, for example. The conductive wire  50 , and the conductive wire  60 , have the same diameter, for example. It should be noted that describing diameters to be the same does not only mean they are exactly the same; instead, it also includes cases where they are roughly the same, or specifically their difference amounts to a manufacturing error or so, and thus they are considered the same. For example, the ratio of the diameter R 2  of the conductive wire  60  to the diameter R 1  of the conductive wire  50 , or (R 2 /R 1 ), is 0.9 or greater but no greater than 1.1, where it may be 0.95 or greater but no greater than 1.05, or 0.98 or greater but no greater than 1.02. The conductive wires  50 ,  60  are each constituted by a metal wire and an insulating film covering the metal wire. The metal wire is formed by, for example, copper, silver, palladium, or silver-palladium alloy, and the like. The insulating film is formed by, for example, polyester imide or polyamide, and the like. 
     The terminal electrodes  70   a ,  70   c  are provided on the flange part  14 . The terminal electrodes  70   a ,  70   c  extend from the connection face  20 , via the exterior face  26 , to the mounting face  22 , of the flange part  14 . The terminal electrodes  70   b ,  70   d  are provided on the flange part  16 . The terminal electrodes  70   b ,  70   d  extend from the connection face  30 , via the exterior face  36 , to the mounting face  32 , of the flange part  16 . The terminal electrodes  70   a  to  70   d  are each a metal film constituted by layering, for example, a base layer of copper, silver, palladium, or silver-palladium alloy, and the like, and a plating layer provided on top of the base layer comprising a nickel layer and a tin layer. 
     One end of the conductive wire  50  is connected to the terminal electrode  70   a  at the connection face  20  of the flange part  14 , while the other end is connected to the terminal electrode  70   b  at the connection face  30  of the flange part  16 . One end of the conductive wire  60  is connected to the terminal electrode  70   c  at the connection face  20  of the flange part  14 , while the other end is connected to the terminal electrode  70   d  at the connection face  30  of the flange part  16 . As described, the connection faces  20 ,  30  of the flange parts  14 ,  16  are faces on which the ends of the conductive wires  50 ,  60  connect to the terminal electrodes  70   a  to  70   d , and face the same side. Also, the mounting faces  22 ,  32  of the flange parts  14 ,  16  are faces on which the coil component  500  is mounted with a solder, etc. 
       FIGS.  3 A to  3 C  are cross-sectional views illustrating how the coil component pertaining to Example 1 is manufactured. It should be noted that, in  FIGS.  3 B and  3 C , the winding direction of the conductive wires  50 ,  60  is indicated by an arrow D. As shown in  FIG.  3 A , a drum core  10  is prepared that includes a winding core  12 , a flange part  14  provided at one end of the winding core  12  in the axial direction, and a flange part  16  provided at the other end of the winding core  12  in the axial direction. In Example 1, a drum core  10  whose winding core  12  has a concaved part  40  formed on it, which is a specified distance away from the flange part  14  and is concaved in a direction crossing (such as a direction crossing at right angles) the axial direction of the winding core  12 , is prepared. The drum core  10 , if formed with a ferrite material, may be formed by molding the material to a desired shape and then heat-treating (sintering) it at approx. 1100° C., for example. The drum core  10 , if formed with metal magnetic grains, may be formed by molding to a desired shape a granular composite magnetic material prepared by mixing metal magnetic grains with a resin, and then heat-treating it at approx. 200° C., for example, to harden the resin. Additionally, the drum core  10 , if formed with metal magnetic grains, may be formed by compacting multiple metal magnetic grains into a desired shape and then heat-treating it at approx. 800° C., for example, in an oxygen atmosphere, thereby allowing the multiple metal magnetic grains to bind together by means of oxide films formed on the surfaces of the metal magnetic grains. It should be noted that the concaved part  40  may be formed in the stage where a desired shape has been formed, or it may be formed by cutting, etc., following the completion of post-molding heat-treatment. 
     After the drum core  10  has been prepared, terminal electrodes  70   a ,  70   c  are formed on the flange part  14 , while terminal electrodes  70   b ,  70   d  are formed on the flange part  16 , which are not illustrated. The terminal electrodes  70   a  to  70   d  may be formed by, for example, bonding metal foils, each constituted by a base layer with a plating layer provided on top, to the flange parts  14 ,  16  using an adhesive, etc. Also, the terminal electrodes  70   a  to  70   d  may be formed by, for example, using the sputtering method to form base layers on the flange parts  14 ,  16  and then forming plating layers on top of the base layers. The base layers may be formed by applying a conductive paste. 
     One end of the conductive wire  50  is connected, at the connection face  20 , to the terminal electrode  70   a  formed on the flange part  14 , after which, as shown in  FIG.  3 B , winding of the conductive wire  50  around the winding core  12  is started in such a way that it is fitted in the concaved part  40  of the winding core  12 , to wind the conductive wire  50  around the winding core  12  from the flange part  14  toward the flange part  16 . In other words, the conductive wire  50  is wound around the winding core  12  from the flange part  14  toward the flange part  16  so that, of the conductive wire  50 , the proximate winding segment  52  at the start of winding, which is wound closest to the flange part  14 , is fitted in the concaved part  40 . Regarding the winding of the conductive wire  50 , it is wound in such a way that its adjacent winding segments contact each other. After the winding of the conductive wire  50  around the winding core  12  is completed, the other end of the conductive wire  50  is led out to the connection face  30  of the flange part  16  and connected to the terminal electrode  70   b  formed on the flange part  16 . Connecting both ends of the conductive wire  50  to the terminal electrodes  70   a ,  70   b  is performed by means of soldering using an unleaded solder, for example. It should be noted that the connection of one end of the conductive wire  50  to the terminal electrode  70   a  formed on the flange part  14  may be performed after the winding of the conductive wire  50  around the winding core  12  is completed. 
     Next, one end of the conductive wire  60  is connected, at the connection face  20 , to the terminal electrode  70   c  formed on the flange part  14 , after which, as shown in  FIG.  3 C , the conductive wire  60  is wound around the winding core  12  on the exterior side of the conductive wire  50  from the flange part  14  toward the flange part  16 . Here, the conductive wire  60  is wound around the winding core  12  in such a way that the center  64  of the cross-section at the proximate winding segment  62  at the start of winding wound closest to the flange part  14 , is positioned closer to the flange part  14  side in the axial direction of the winding core  12  than is the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , and that the spacing in the axial direction of the winding core  12 , between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , becomes smaller than the radius of the conductive wire  50 . In Example 1, the conductive wire  50  is wound around the winding core  12  so that the proximate winding segment  52  of the conductive wire  50  is fitted in the concaved part  40  of the winding core  12 , and then the conductive wire  60  is wound around the winding core  12  on the exterior side of the conductive wire  50  so that the proximate winding segment  62  of the conductive wire  60  contacts the flange part  14 . This way, the conductive wire  60  can be wound around the winding core  12  in such a way that the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  is positioned closer to the flange part  14  side than is the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , and that the spacing in the axial direction of the winding core  12 , between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , becomes smaller than the radius of the conductive wire  50 . 
     As for the winding of the conductive wire  60 , it is wound in such a way that its adjacent winding segments contact each other. After the winding of the conductive wire  60  around the winding core  12  is completed, the other end of the conductive wire  60  is led out to the connection face  30  of the flange part  16  and connected to the terminal electrode  70   d  formed on the flange part  16 . Connecting both ends of the conductive wire  60  to the terminal electrodes  70   c ,  70   d  is performed by means of soldering using an unleaded solder, for example. It should be noted that the connection of one end of the conductive wire  60  to the terminal electrode  70   c  formed on the flange part  14  may be performed after the winding of the conductive wire  60  around the winding core  12  is completed. 
       FIGS.  4 A to  4 C  are cross-sectional views illustrating how the coil component pertaining to Comparative Example 1 is manufactured. It should be noted that, in  FIGS.  4 B and  4 C , the winding direction of the conductive wires  50 ,  60  is indicated by an arrow D. As shown in  FIG.  4 A , a drum core  110  is prepared that includes a winding core  112  and flange parts  114 ,  116  provided at both ends of the winding core  112  in the axial direction. In the winding core  112 , no concaved part is formed, which is different from the winding core  12  in Example 1. After the drum core  110  has been prepared, terminal electrodes  70   a ,  70   c  are formed on the flange part  114 , while terminal electrodes  70   b ,  70   d  are formed on the flange part  116 , which are not illustrated. 
     Next, one end of the conductive wire  50  is connected to the terminal electrode  70   a  formed on the flange part  114 , after which, as shown in  FIG.  4 B , the conductive wire  50  is wound around the winding core  112  from the flange part  114  toward the flange part  116 . After the winding of the conductive wire  50  around the winding core  112  is completed, the other end of the conductive wire  50  is led out to the flange part  116  and connected to the terminal electrode  70   b  formed on the flange part  116 . It should be noted that the connection of one end of the conductive wire  50  to the terminal electrode  70   a  formed on the flange part  114  may be performed after the winding of the conductive wire  50  around the winding core  112  is completed. 
     Next, one end of the conductive wire  60  is connected to the terminal electrode  70   c  formed on the flange part  114 , after which, as shown in  FIG.  4 C , the conductive wire  60  is wound around the winding core  112  on the exterior side of the conductive wire  50  from the flange part  114  toward the flange part  116 . Since the conductive wire  60  stabilizes when it enters the hollows between the adjacent winding segments of the conductive wire  50 , the conductive wire  60  is wound in a manner entering the hollows between the adjacent winding segments of the conductive wire  50 . Now, assume that the conductive wire  50  is wound around the winding core  112  by the maximum number of turns possible between the flange part  114  and the flange part  116 ; in this case, trying to wind the conductive wire  60  on the exterior side of the conductive wire  50  by the same number of turns as the conductive wire  50 , may cause the last winding segment  66  of the conductive wire  60  that happens at the very end, to be wound on the exterior side of the winding segments before the last winding segment  66 . After the winding of the conductive wire  60  around the winding core  112  is completed, the other end of the conductive wire  60  is led out to the flange part  116  and connected to the terminal electrode  70   d  formed on the flange part  116 . It should be noted that the connection of one end of the conductive wire  60  to the terminal electrode  70   c  formed on the flange part  114  may be performed after the winding of the conductive wire  60  around the winding core  112  is completed. 
     According to Comparative Example 1, the last winding segment  66  of the conductive wire  60  is wound around the winding core  112  on the exterior side of the winding segments before the last winding segment  66 . Accordingly, it is required that the flange parts  114 ,  116  be made larger so that the last winding segment  66  of the conductive wire  60  can be accommodated between the flange part  114  and the flange part  116 . As a result, the coil component size increases. In the meantime, lengthening the winding core  112  by the diameter of the conductive wire  60  is also a possibility so that the last winding segment  66  of the conductive wire  60  can be wound in an aligned manner in the same layer as the wound portions before the last winding segment  66 ; in this case, too, the winding core  112  becomes longer and the coil component size increases as a result. 
     According to Example 1, on the other hand, the conductive wire  60  is wound around the winding core  12  on the exterior side of the conductive wire  50  in such a way that the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  at the start of winding turning closest to the flange part  14 , is positioned closer to the flange part  14  side in the axial direction of the winding core  12  than is the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50  at the start of winding turning closest to the flange part  14 , as shown in  FIG.  3 C . Here, the spacing X 2  (refer to  FIG.  2 B ) in the axial direction of the winding core  12 , between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , is made smaller than the radius of the conductive wire  50 . This way, the positioning of the last winding segment  66  of the conductive wire  60  on the exterior side of the winding segments before it can be prevented, even when the conductive wire  50  is wound around the winding core  12  by the maximum number of turns possible between the flange part  14  and the flange part  16 , and the conductive wire  60  is wound around the winding core  12  on the exterior side of the conductive wire  50  by the same number of turns as the conductive wire  50 . The result is that the flange parts  14 ,  16  need not be increased in size. Also, elongating the length of the winding core  12  within a range shorter than the radius of the conductive wire  60  can prevent the last winding segment  66  of the conductive wire  60  from positioning on the exterior side of the turned portions before it. This means that, according to Example 1, size increase in the coil component  500  can be prevented. 
     Also, according to Example 1, all wound portions of the conductive wire  60  can be formed in a manner aligned in a single layer. In the case of  FIG.  4 C  under Comparative Example 1, for example, the last winding segment  66  of the conductive wire  60  may shift in such a way that it enters the hollow between adjacent winding segments among the winding segments before the last winding segment  66 . In this case, parasitic capacitance may generate and high-frequency characteristics may deteriorate. In Example 1, on the other hand, all winding segments of the conductive wire  60  are formed in a manner aligned in a single layer; this prevents generation of parasitic capacitance, which in turn prevents deterioration in high-frequency characteristics. 
     Also, according to Example 1, a drum core  10  whose winding core  12  has a concaved part  40  which is positioned away from the flange part  14  and concaved in a direction crossing the axial direction of the winding core  12 , is prepared, as shown in  FIG.  3 A . As shown in  FIG.  3 B , the conductive wire  50  is wound around the winding core  12  in a manner allowing the proximate winding segment  52  of the conductive wire  50  to fit in the concaved part  40 . As shown in  FIG.  3 C , the conductive wire  60  is wound around the winding core  12  in a manner allowing the proximate winding segment  62  of the conducive wire  60  to contact the flange part  14 . This way, winding of the conductive wire  60  around the winding core  12  in such a way that the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  is positioned closer to the flange part  14  side in the axial direction of the winding core  12  than is the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , and that the spacing in the axial direction of the winding core  12  between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50  becomes smaller than the radius of the conductive wire  50 , can be realized with ease. 
     The concaved part  40  only needs to have such depth and width that can fix the proximate winding segment  52  of the conductive wire  50  in an immovable manner. For example, the width of the concaved part  40  may be 0.5 times or greater but no greater than 1.5 times, or 0.8 times or greater but no greater than 1 times, the diameter of the conductive wire  50 . The depth of the concaved part  40  may be 0.2 times or greater but smaller than 1 times, or 0.3 times or greater but no greater than 0.8 times, or 0.4 times or greater but no greater than 0.5 times, the diameter of the conductive wire  50 . 
     The spacing X 1  (refer to  FIG.  2 B ) between the flange part  14  and the concaved part  40  only needs to be a spacing that allows the spacing between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50  to become smaller than the radius of the conductive wire  50 . For example, the spacing X 1  may be 0.1 times or greater but smaller than 0.5 times, or 0.2 times or greater but no greater than 0.45 times, or 0.3 times or greater but no greater than 0.4 times, the diameter of the conductive wire  60 . Additionally, while preferably the concaved part  40  is formed continuously all around the periphery of the winding core  12 , it may be partially disrupted or formed only in some portions. 
     Example 2 
     The coil component pertaining to Example 2 is a common mode choke coil just like the one in Example 1, and because its plan views are the same as  FIGS.  1 A to  1 C  in Example 1, they are not illustrated or explained.  FIGS.  5 A to  5 C  are cross-sectional views illustrating how the coil component pertaining to Example 2 is manufactured. It should be noted that, in  FIGS.  5 B and  5 C , the winding direction of the conductive wires  50 ,  60  is indicated by an arrow D. As shown in  FIG.  5 A , a drum core  10  is prepared that includes a winding core  12   a  and flange parts  14 ,  16  provided at both ends of the winding core  12   a  in the axial direction. In Example 2, a drum core  10  whose winding core  12   a  has a projecting part  42  formed on it, which is contacting the flange part  14  and projecting in a direction crossing (such as a direction crossing at right angles) the axial direction of the winding core  12   a , is prepared. The projecting part  42  is formed all around the winding core  12   a , for example. The projecting part  42 , just like the concaved part  40  in Example 1, may be formed in the stage where a desired shape has been formed in the drum core  10  forming step, or it may be formed by cutting, etc., following the completion of post-molding heat-treatment. After the drum core  10  has been prepared, terminal electrodes  70   a ,  70   c  are formed on the flange part  14 , while terminal electrodes  70   b ,  70   d  are formed on the flange part  16 , which are not illustrated. 
     Next, one end of the conductive wire  50  is connected to the terminal electrode  70   a  formed on the flange part  14 , after which, as shown in  FIG.  5 B , the conductive wire  50  is wound around the winding core  12   a  from the flange part  14  toward the flange part  16  between the projecting part  42  and the flange part  16 . In other words, the conductive wire  50  is wound around the winding core  12   a  from the flange part  14  toward the flange part  16  in such a way that the proximate winding segment  52  of the conductive wire  50  contacts the side face of the projecting part  42  on the flange part  16  side which crosses (such as crosses at right angles) the axial direction of the winding core  12   a . After the winding of the conductive wire  50  around the winding core  12   a  is completed, the other end of the conductive wire  50  is led out to the flange part  16  and connected to the terminal electrode  70   b  formed on the flange part  16 . It should be noted that the connection of one end of the conductive wire  50  to the terminal electrode  70   a  formed on the flange part  14  may be performed after the winding of the conductive wire  50  around the winding core  12   a  is completed. 
     Next, one end of the conductive wire  60  is connected to the terminal electrode  70   c  formed on the flange part  14 , after which, as shown in  FIG.  5 C , the conductive wire  60  is wound around the winding core  12   a  on the exterior side of the conductive wire  50  from the flange part  14  toward the flange part  16 . Here, the conductive wire  60  is wound around the winding core  12   a  from the flange part  14  toward the flange part  16  in such a way that the proximate winding segment  62  of the conductive wire  60  contacts the flange part  14 . After the winding of the conductive wire  60  around the winding core  12   a  is completed, the other end of the conductive wire  60  is led out to the flange part  16  and connected to the terminal electrode  70   d  formed on the flange part  16 . It should be noted that the connection of one end of the conductive wire  60  to the terminal electrode  70   c  formed on the flange part  14  may be performed after the winding of the conductive wire  60  around the winding core  12   a  is completed. 
     According to Example 2, a drum core  10  whose winding core  12   a  has a projecting part  42  which is contacting the flange part  14  and projecting in a direction that crosses the axial direction of the winding core  12   a , is prepared, as shown in  FIG.  5    A. As shown in  FIG.  5 B , the conductive wire  50  is wound around the winding core  12   a  between the projecting part  42  and the flange part  16  in a manner allowing the proximate  52  of the conductive wire  50  to contact the side face of the projecting part  42  that crosses the axial direction of the winding core  12   a . As shown in  FIG.  5 C , the conductive wire  60  is wound around the winding core  12   a  in a manner allowing the proximate winding segment  62  of the conducive wire  60  to contact the flange part  14 . This way, winding of the conductive wire  60  around the winding core  12   a  in such a way that the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  is positioned closer to the flange part  14  side in the axial direction of the winding core  12   a  than is the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , and that the spacing in the axial direction of the winding core  12   a  between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50  becomes smaller than the radius of the conductive wire  50 , can be realized with ease. 
     The height of the projecting part  42  only needs to be a height that prevents the proximate winding segment  52  of the conductive wire  50  from moving to the flange part  14  side. For example, the height of the projecting part  42  may be 0.2 times or greater but no greater than 1 times, or 0.3 times or greater but no greater than 0.8 times, or 0.4 times or greater but no greater than 0.6 times or 0.5 times, the diameter of the conductive wire  50 . The width of the projecting part  42  only needs to be a width that makes the spacing in the axial direction of the winding core  12   a  between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , smaller than the radius of the conductive wire  50 . For example, the width of the projecting part  42  may be 0.1 times or greater but less than 0.5 times, or 0.2 times or greater but no greater than 0.45 times, or 0.3 times or greater but no greater than 0.4 times, the diameter of the conductive wire  60 . Additionally, while preferably the projecting part  42  is formed continuously all around the periphery of the winding core  12   a , it may be partially disrupted or formed only in some portions. 
     Example 3 
     The coil component pertaining to Example 3 is a common mode choke coil just like the one in Example 1, and because its plan views are the same as  FIGS.  1 A to  1 C  in Example 1, they are not illustrated or explained.  FIGS.  6 A to  6 C  are cross-sectional views illustrating how the coil component pertaining to Example 3 is manufactured. It should be noted that, in  FIGS.  6 B and  6 C , the winding direction of the conductive wires  50 ,  60  is indicated by an arrow D. As shown in  FIG.  6 A , a drum core  10  is prepared that includes a winding core  12   b  and flange parts  14 ,  16  provided at both ends of the winding core  12   b  in the axial direction. In Example 3, a drum core  10  whose winding core  12   b  has a concaved part  44  provided on it, which is contacting the flange part  14  and whose depth gradually increases for points further away from the flange part  14 , is prepared. In other words, a drum core  10  whose winding core  12   b  has a concaved part  44  provided on it, which is contacting the flange part  14  and having a face sloped so that the diameter of the winding core  12   b  decreases for points further away from the flange part  14 , is prepared. The concaved part  44  is formed all around the winding core  12   b , for example. The concaved part  44 , just like the concaved part  40  in Example 1, may be formed in the stage where a desired shape has been formed in the drum core  10  forming step, or it may be formed by cutting, etc., following the completion of post-molding heat-treatment. After the drum core  10  has been prepared, terminal electrodes  70   a ,  70   c  are formed on the flange part  14 , while terminal electrodes  70   b ,  70   d  are formed on the flange part  16 , which are not illustrated. 
     Next, one end of the conductive wire  50  is connected to the terminal electrode  70   a  formed on the flange part  14 , after which, as shown in  FIG.  6 B , the conductive wire  50  is wound around the winding core  12   b  from the flange part  14  toward the flange part  16  in a manner allowing the proximate winding segment  52  of the conductive wire  50  to fit in the concaved part  44 . Because the concaved part  44  is shaped so that it becomes gradually deeper for points further away from the flange part  14 , having a face sloped so that the diameter of the winding core  12   b  decreases for points further away from the flange part  14 , the conductive wire  50  is wound around the winding core  12   b  with the proximate winding segment  52  contacting the side face of the concaved part  44  on the flange part  16  side. After the winding of the conductive wire  50  around the winding core  12   b  is completed, the other end of the conductive wire  50  is led out to the flange part  16  and connected to the terminal electrode  70   b  formed on the flange part  16 . It should be noted that the connection of one end of the conductive wire  50  to the terminal electrode  70   a  formed on the flange part  14  may be performed after the winding of the conductive wire  50  around the winding core  12   b  is completed. 
     Next, one end of the conductive wire  60  is connected to the terminal electrode  70   c  formed on the flange part  14 , after which, as shown in  FIG.  6 C , the conductive wire  60  is wound around the winding core  12   b  on the exterior side of the conductive wire  50  from the flange part  14  toward the flange part  16 . Here, the conductive wire  60  is wound around the winding core  12   b  from the flange part  14  toward the flange part  16  in a manner allowing the proximate winding segment  62  of the conductive wire  60  to contact the flange part  14 . After the winding of the conductive wire  60  around the winding core  12   b  is completed, the other end of the conductive wire  60  is led out to the flange part  16  and connected to the terminal electrode  70   d  formed on the flange part  16 . It should be noted that the connection of one end of the conductive wire  60  to the terminal electrode  70   c  formed on the flange part  14  may be performed after the winding of the conductive wire  60  around the winding core  12   b  is completed. 
     According to Example 3, a drum core  10  whose winding core  12   b  has a concaved part  44  that includes a face sloped so that the diameter of the winding core  12   b  decreases for points further away from the flange part  14 , is prepared, as shown in  FIG.  6 A . As shown in  FIG.  6 B , the conductive wire  50  is wound around the winding core  12   b  in a manner allowing the proximate winding segment  52  of the conductive wire  50  to fit in the concaved part  44 . As shown in  FIG.  6 C , the conductive wire  60  is wound around the winding core  12   b  in a manner allowing the proximate winding segment  62  of the conducive wire  60  to contact the flange part  14 . This way, winding of the conductive wire  60  around the winding core  12   b  in such a way that the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  is positioned closer to the flange part  14  side in the axial direction of the winding core  12   b  than is the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , and that the spacing in the axial direction of the winding core  12   b  between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50  becomes smaller than the radius of the conductive wire  50 , can be realized with ease. Additionally, the concaved part  40  described in Example 1 is required to have a size corresponding to the diameter of the conductive wire  50 ; according to the concaved part  44  described in Example 3, on the other hand, the range of conductive wire  50  diameters that can be accommodated increases compared to Example 1. 
     While the concaved part  44  is provided in contact with the flange part  14  in the illustrated example, it may be provided away from the flange part  14 . Additionally, while preferably the concaved part  44  is formed continuously all around the periphery of the winding core  12   b , it may be partially disrupted or formed only in some portions. The width of the concaved part  44  may be greater than 1 times but smaller than 1.5 times, or 1.2 times or greater but smaller than 1.5 times, the diameter of the conductive wire  50 , for example. The depth of the deepest part of the concaved part  44  may be 0.5 times or greater but smaller than 1 times, or 0.6 times or greater but no greater than 0.8 times, the diameter of the conductive wire  50 . 
     Example 4 
     The coil component pertaining to Example 4 is a common mode choke coil just like the one in Example 1, and because its plan views are the same as  FIGS.  1 A to  1 C  in Example 1, they are not illustrated or explained.  FIGS.  7 A to  7 C  are cross-sectional views illustrating how the coil component pertaining to Example 4 is manufactured. It should be noted that, in  FIGS.  7 B and  7 C , the winding direction of the conductive wires  50 ,  60  is indicated by an arrow D. As shown in  FIG.  7 A , a drum core  10  is prepared that includes a winding core  12   c  and flange parts  14   a ,  16   a  provided at both ends of the winding core  12   c  in the axial direction. In Example 4, a drum core  10  whose winding core  12   c  has no concaved part or projecting part provided on it, and which has a slope so that the thicknesses of the flange parts  14   a ,  16   a  in the axial direction of the winding core  12   c  increase for points on the interior faces  24 ,  34  of the flange parts  14   a ,  16   a  closer to the winding core  12   c , is prepared. The angle θ of each of the interior faces  24 ,  34  of the flange parts  14   a ,  16   a , with respect to the winding core  12   c , is greater than 90° but smaller than 120°, and it may be 95° or greater but no greater than 115°, or 100° or greater but no greater than 110°, for example. After the drum core  10  has been prepared, terminal electrodes  70   a ,  70   c  are formed on the flange part  14   a , while terminal electrodes  70   b ,  70   d  are formed on the flange part  16   a , which are not illustrated 
     Next, one end of the conductive wire  50  is connected to the terminal electrode  70   a  formed on the flange part  14   a , after which, as shown in  FIG.  7 B , the conductive wire  50  is wound around the winding core  12   c  from the flange part  14   a  toward the flange part  16   a . Here, the conductive wire  50  is wound around the winding core  12   c  from the flange part  14   a  toward the flange part  16   a  in a manner allowing the proximate winding segment  52  of the conductive wire  50  to contact the interior face  24  of the flange part  14   a . After the winding of the conductive wire  50  around the winding core  12   c  is completed, the other end of the conductive wire  50  is led out to the flange part  16   a  and connected to the terminal electrode  70   b  formed on the flange part  16   a . It should be noted that the connection of one end of the conductive wire  50  to the terminal electrode  70   a  formed on the flange part  14   a  may be performed after the winding of the conductive wire  50  around the winding core  12   c  is completed. 
     Next, one end of the conductive wire  60  is connected to the terminal electrode  70   c  formed on the flange part  14   a , after which, as shown in  FIG.  7 C , the conductive wire  60  is wound around the winding core  12   c  on the exterior side of the conductive wire  50  from the flange part  14   a  toward the flange part  16   a . Here, the conductive wire  60  is wound around the winding core  12   c  from the flange part  14   a  toward the flange part  16   a  in a manner allowing the proximate winding segment  62  of the conductive wire  60  to contact the interior face  24  of the flange part  14   a . After the winding of the conductive wire  60  around the winding core  12   c  is completed, the other end of the conductive wire  60  is led out to the flange part  16   a  and connected to the terminal electrode  70   d  formed on the flange part  16   a . It should be noted that the connection of one end of the conductive wire  60  to the terminal electrode  70   c  formed on the flange part  14   a  may be performed after the winding of the conductive wire  60  around the winding core  12   c  is completed. 
     According to Example 4, a drum core  10  having a slope so that the thickness of the flange part  14   a  in the axial direction of the winding core  12   c  increases for points on the interior face  24  of the flange part  14   a  closer to the winding core  12   c , is prepared, as shown in  FIG.  7 A . As shown in  FIG.  7 B , the conductive wire  50  is wound around the winding core  12   c  in a manner allowing the proximate winding segment  52  of the conductive wire  50  to contact the interior face  24  of the flange part  14   a . As shown in  FIG.  7 C , the conductive wire  60  is wound around the winding core  12   c  in a manner allowing the proximate winding segment  62  of the conducive wire  60  to contact the interior face  24  of the flange part  14   a . This way, winding of the conductive wire  60  around the winding core  12   c  in such a way that the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  is positioned closer to the flange part  14   a  side in the axial direction of the winding core  12   c  than is the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , and that the spacing in the axial direction of the winding core  12   c  between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50  becomes smaller than the radius of the conductive wire  50 , can be realized with ease. Also, according to Example 4, conductive wires  50 ,  60  of various sizes can be supported. 
     In Example 4, the interior face  34  of the flange part  16   a  has a slope in the illustrated example; however, the interior face  34  of the flange part  16   a  may be orthogonal to the axial direction of the winding core  12   c . Also, while in the illustrated example the entire interior face  24  of the flange part  14   a  has a slope, except for the portion to which the winding core  12   c  is connected, it suffices that, of the interior face  24  of the flange part  14   a , at least the portions contacted by the proximate winding segment  52  of the conductive wire  50  and proximate winding segment  62  of the conductive wire  60  have a slope. Additionally, while preferably the portions of the interior face  24  of the flange part  14   a  having a slope are formed continuously all around the periphery of the winding core  12   c , they may include portions without a sloped face along the way, or be formed only partially. 
     Example 5 
     The coil component pertaining to Example 5 is a common mode choke coil just like the one in Example 1, and because its plan views are the same as  FIGS.  1 A to  1 C  in Example 1, they are not illustrated or explained.  FIGS.  8 A to  8 C  are cross-sectional views illustrating how the coil component pertaining to Example 5 is manufactured. It should be noted that, in  FIGS.  8 B and  8 C , the winding direction of the conductive wires  50 ,  60  is indicated by an arrow D. As shown in  FIG.  8 A , a drum core  10  is prepared that includes a winding core  12   c  and flange parts  14 ,  16  provided at both ends of the winding core  12   c  in the axial direction. Next, a spacer part  46  is formed over a portion of the interior face  24  of the flange part  14  to which the winding core  12   c  is not connected, in a manner contacting the interior face  24 . The spacer part  46  is provided all around the periphery of the winding core  12   c , for example, but it may be disrupted along the way or formed only in some portions. The spacer part  46  may be formed by an insulating member, or it may be formed by a metal member. Because it will be removed as described below, preferably the spacer part  46  is not bonded to the flange part  14 . After the drum core  10  has been prepared, terminal electrodes  70   a ,  70   c  are formed on the flange part  14 , while terminal electrodes  70   b ,  70   d  are formed on the flange part  16 , which are not illustrated, before or after the forming of the spacer part  46 . 
     Next, one end of the conductive wire  50  is connected to the terminal electrode  70   a  formed on the flange part  14 , after which, as shown in  FIG.  8 B , the conductive wire  50  is wound around the winding core  12   c  from the flange part  14  toward the flange part  16  between the spacer part  46  and the flange part  16 . In other words, the conductive wire  50  is wound around the winding core  12   c  from the flange part  14  toward the flange part  16  in such a way that the proximate winding segment  52  of the conductive wire  50  contacts the side face of the spacer part  46  which is positioned on the flange part  16  side and crossing (such as crossing at right angles) the axial direction of the winding core  12   c . After the winding of the conductive wire  50  around the winding core  12   c  is completed, the other end of the conductive wire  50  is led out to the flange part  16  and connected to the terminal electrode  70   b  formed on the flange part  16 . It should be noted that the connection of one end of the conductive wire  50  to the terminal electrode  70   a  formed on the flange part  14  may be performed after the winding of the conductive wire  50  around the winding core  12   c  is completed. 
     Next, the conductive wire  50  is fixed in an immovable manner, after which the spacer part  46  is removed from the drum core  10 . The fixing of the conductive wire  50  may be performed using an adhesive, for example. Thereafter, one end of the conductive wire  60  is connected to the terminal electrode  70   c  formed on the flange part  14 , after which, as shown in  FIG.  8 C , the conductive wire  60  is wound around the winding core  12   c  on the exterior side of the conductive wire  50  from the flange part  14  toward the flange part  16 . Here, the conductive wire  60  is wound around the winding core  12   c  from the flange part  14  toward the flange part  16  in a manner allowing the proximate winding segment  62  of the conductive wire  60  to contact the flange part  14 . After the winding of the conductive wire  60  around the winding core  12   c  is completed, the other end of the conductive wire  60  is led out to the flange part  16  and connected to the terminal electrode  70   d  formed on the flange part  16 . It should be noted that the connection of one end of the conductive wire  60  to the terminal electrode  70   c  formed on the flange part  14  may be performed after the winding of the conductive wire  60  around the winding core  12   c  is completed. 
     According to Example 5, a spacer part  46  is formed around the winding core  12   c  in a manner contacting the flange part  14 , as shown in  FIG.  8 A . As shown in  FIG.  8    B, the conductive wire  50  is wound around the winding core  12   c  in a manner allowing the proximate winding segment  52  of the conductive wire  50  to contact the side face of the spacer part  46  crossing the axial direction of the winding core  12   c . As shown in  FIG.  8 C , the conductive wire  60  is wound around the winding core  12   c , after the spacer part  46  has been removed, in a manner allowing the proximate winding segment  62  of the conducive wire  60  to contact the flange part  14 . This way, winding of the conductive wire  60  around the winding core  12   c  in such a way that the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  is positioned closer to the flange part  14  side in the axial direction of the winding core  12   c  than is the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , and that the spacing in the axial direction of the winding core  12   c  between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50  becomes smaller than the radius of the conductive wire  50 , can be realized with ease. 
     The thickness of the spacer part  46  only needs to be a thickness that makes the spacing in the axial direction of the winding core  12   c  between the center  64  of the cross-section at the proximate winding segment  62  of the conductive wire  60  and the center  54  of the cross-section at the proximate winding segment  52  of the conductive wire  50 , smaller than the radius of the conductive wire  50 . For example, the thickness of the spacer part  46  may be 0.1 times or greater but smaller than 0.5 times, or 0.2 times or greater but no greater than 0.45 times, or 0.3 times or greater but no greater than 0.4 times, the diameter of the conductive wire  60 . Also, the spacer part  46  is not necessarily formed over the entire surface of the interior face  24  of the flange part  14 , except for the portion to which the winding core  12   c  is connected; instead, it only needs to be formed at least in a portion contacted by the proximate winding segment  52  of the conductive wire  50 . Additionally, while preferably the spacer part  46  is provided all around the periphery of the winding core  12   c , it may be disrupted along the way or formed only in some portions. 
     While Examples 1 to 5 illustrated examples where the coil component is a common mode choke coil, other coil components are also acceptable so long as the coil components have multiple conductive wires layered around the winding core.  FIG.  9 A  is a plan view, while  FIG.  9 B  is a plan view seen from direction A in  FIG.  9 A , of a coil component for single line. It should be noted that, in  FIG.  9 A , the illustration of the windings of the conductive wires  50 ,  60  is simplified for the sake of clarity of figures. Also, in  FIGS.  9 A and  9 B , the conductive wire  50  and terminal electrodes  70   e ,  70   f  are hatched for the sake of clarity of figures. 
     As shown in  FIGS.  9 A and  9 B , the coil component  600  for single line has terminal electrodes  70   e ,  70   f  provided on the flange part  14 , but no terminal electrode provided on the flange part  16 . The terminal electrodes  70   e ,  70   f  extend from the connection face  20 , via the exterior face  26 , to the mounting face  22 , of the flange part  14 . One end of the conductive wire  50  being wound around the winding core  12  (not illustrated in  FIGS.  9 A and  9 B ) of the drum core  10  is connected to the terminal electrode  70   e , while the other end is connected to the terminal electrode  70   f . One end of the conductive wire  60  being wound around the winding core  12  on the exterior side of the conductive wire  50  is connected to the terminal electrode  70   e , while the other end is connected to the terminal electrode  70   f . The external dimensions of the drum core  10  are 3.2 mm in length dimension, 2.5 mm in width dimension, and 2.4 mm in height dimension, in one example. 
     With the coil component  600  for a single line, the electrical current input to one of the terminal electrodes  70   e ,  70   f  flows to the other terminal electrode by traveling through both the conductive wires  50 ,  60 , which allows for reduction in resistance. Such coil component  600  is used for DC-DC converters, for example. Also, because deterioration in its high-frequency characteristics is prevented, as explained in Example 1, the coil component  600  can support wide frequency bands for noise elimination. 
     The foregoing described the examples of the present invention in detail; however, the present invention is not limited to these specific examples, and various modifications and changes may be added so long as doing so does not deviate from the key points of the present invention as described in “What Is Claimed Is.”