Patent Publication Number: US-2023135284-A1

Title: Coil component

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims benefit of priority to Japanese Patent Application No. 2021-176448 filed Oct. 28, 2021, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     Technical Field 
     The present disclosure relates to a coil component including: a core including a winding core portion around which a wire is wound and a first flange portion and a second flange portion that are provided at the respective end portions of the winding core portion; and a top plate fixed to the core to be spanned between the first flange portion and the second flange portion, in particular, to the structure of a coupling portion between a core and a top plate. 
     Background Art 
     For example, Japanese Unexamined Patent Application Publication No. 2011-96815 describes a coil component including: a core including a winding core portion around which a wire is wound and a first flange portion and a second flange portion that are provided at the respective end portions of the winding core portion; and a top plate adhesive fixed to the core to be spanned between the first flange portion and the second flange portion. 
     The first flange portion and the second flange portion each have a bottom surface that faces a mounting substrate when the coil component is mounted, a top surface on the opposite side of the bottom surface, and an outer-side end surface that couples the bottom surface and the top surface to each other and is located on the opposite side of the winding core portion. The top plate described above is fixed to the core with an adhesive interposed therebetween while the lower main surface of the top plate is facing the top surface of each of the first flange portion and the second flange portion. 
     The first flange portion and the second flange portion are each provided with at least one terminal electrode. The terminal electrode is provided to integrally extend along each of the first flange portion and the second flange portion from the bottom surface to the top surface through the outer-side end surface. 
     Each end portion of the wire wound around the winding core portion is connected to the terminal electrode, and the connection portion between the end portion of the wire and the terminal electrode is located on the top surface of each of the first flange portion and the second flange portion. Thus, the top plate described above is placed at a predetermined distance from the top surface of each of the first flange portion and the second flange portion so that a magnetic gap can be formed between the flange portions and the top plate. This magnetic gap prevents the occurrence of magnetic saturation, thereby contributing to the improvement of the DC superimposition characteristics. 
     SUMMARY 
     In recent years, coil components high in current and inductance value have been increasingly demanded, and it is thus required to improve DC superimposition characteristics while acquiring a high inductance value. 
     Japanese Unexamined Patent Application Publication No. 2011-96815 describes the structure in which the gap is formed between the top plate and the core to improve the DC superimposition characteristics. 
     However, as described in Japanese Unexamined Patent Application Publication No. 2011-96815, in a coil component including a top plate and a core, desired inductance value and DC superimposition characteristics are obtained with the top plate and the core facing each other in a predetermined positional relationship. In other words, in order to obtain desired characteristics, the positional relationship between the top plate and the core is important. To achieve this, it is required that in the manufacturing stage of the coil component, the top plate and the core are assembled in a stable positional relationship. However, Japanese Unexamined Patent Application Publication No. 2011-96815 describes the gap but does not describe position control between the top plate and the core at points other than the gap. 
     In view of this, the present disclosure provides the structure of a coil component in which a stable positional relationship can be achieved while a gap is formed between a top plate and a core. 
     The present disclosure is directed to a coil component including: a core that includes a winding core portion that extends in an axial direction and a first flange portion and a second flange portion that are provided at a first end and a second end, respectively, that are opposite ends in the axial direction of the winding core portion; a top plate that has a lower main surface and an upper main surface that face directions opposite to each other; at least one wire wound around the winding core portion; and a first terminal electrode and a second terminal electrode that are electrically connected to respective end portions of the wire and provided at the first flange portion and the second flange portion, respectively. 
     The first flange portion and the second flange portion each have a bottom surface that faces a mounting substrate when the coil component is mounted and a top surface on an opposite side of the bottom surface. The top plate is fixed to the core with an adhesive interposed therebetween while the lower main surface is facing the top surface of each of the first flange portion and the second flange portion. 
     The present disclosure has the feature of having the following configuration in view of the technical problem described above. 
     When one of the top surface of at least one of the first flange portion and the second flange portion and the lower main surface is defined as a first surface and another thereof is defined as a second surface, a projection is provided on the first surface and a recess for receiving the projection is provided in the second surface. 
     At least one of an outer surface of the projection and a wall surface that defines the recess is provided with a guide surface capable of guiding the projection into the recess. 
     The outer surface of the projection and the wall surface that defines the recess form a first abutment portion and a second abutment portion, respectively, that are brought into abutment against each other when the recess receives the projection. An abutment between the first abutment portion and the second abutment portion defines a termination end of the projection inserted into the recess with a gap formed between the first surface and the second surface, thereby achieving positioning in a direction of the insertion and achieves alignment of the top plate relative to the core in at least one of directions along the first surface and the second surface. 
     According to the present disclosure, with the presence of the guide surfaces described above, the projection is smoothly guided into the recess and the first abutment portion and the second abutment portion described above are thus brought into abutment against each other, with the result that positioning in the predetermined direction between the top plate and the core is achieved while the gap is formed between the top plate and the core. Thus, in the manufacturing stage of the coil component, a stable positional relationship can be achieved while the gap is formed between the top plate and the core. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS.  1 A and  1 B  illustrate the appearance of a coil component according to a first embodiment of the present disclosure, in which  FIG.  1 A  is a front view and  FIG.  1 B  is a left-side view; 
         FIGS.  2 A and  2 B  separately illustrate a top plate and a core that are included in the coil component illustrated in  FIGS.  1 A and  1 B , in which  FIG.  2 A  is a bottom view of the top plate and  FIG.  2 B  is a top view of the core; 
         FIG.  3    is an enlarged sectional view taken along the line C-C of  FIGS.  2 A and  2 B , schematically illustrating the top plate and the core, which are illustrated in  FIGS.  2 A and  2 B , fixed to each other with an adhesive interposed therebetween; 
         FIG.  4    is a view corresponding to  FIG.  3   , illustrating a second embodiment of the present disclosure and schematically illustrating the top plate and the core fixed to each other with the adhesive interposed therebetween; 
         FIG.  5    is a view corresponding to  FIG.  3   , illustrating a third embodiment of the present disclosure and schematically illustrating the top plate and the core fixed to each other with the adhesive interposed therebetween; 
         FIG.  6    is a view corresponding to  FIG.  3   , illustrating a fourth embodiment of the present disclosure and schematically illustrating the top plate and the core fixed to each other with the adhesive interposed therebetween; 
         FIG.  7    is a view corresponding to  FIG.  3   , illustrating a fifth embodiment of the present disclosure and schematically illustrating the top plate and the core fixed to each other with the adhesive interposed therebetween; 
         FIG.  8    is a view corresponding to  FIG.  3   , illustrating a sixth embodiment of the present disclosure and schematically illustrating the top plate and the core fixed to each other with the adhesive interposed therebetween; 
         FIG.  9    is a view corresponding to  FIG.  3   , illustrating a seventh embodiment of the present disclosure and schematically illustrating the top plate and the core fixed to each other with the adhesive interposed therebetween; 
         FIGS.  10 A and  10 B  are views corresponding to  FIGS.  2 A and  2 B , illustrating an eighth embodiment of the present disclosure and separately illustrating the top plate and the core; 
         FIGS.  11 A and  11 B  are views corresponding to  FIGS.  2 A and  2 B , illustrating a ninth embodiment of the present disclosure and separately illustrating the top plate and the core; 
         FIGS.  12 A and  12 B  are views corresponding to  FIGS.  2 A and  2 B , illustrating a tenth embodiment of the present disclosure and separately illustrating the top plate and the core; 
         FIGS.  13 A and  13 B  are views corresponding to  FIGS.  2 A and  2 B , illustrating an eleventh embodiment of the present disclosure and separately illustrating the top plate and the core; 
         FIGS.  14 A and  14 B  are views corresponding to  FIGS.  2 A and  2 B , illustrating a twelfth embodiment of the present disclosure and separately illustrating the top plate and the core; 
         FIGS.  15 A and  15 B  are views corresponding to  FIGS.  2 A and  2 B , illustrating a thirteenth embodiment of the present disclosure and separately illustrating the top plate and the core; 
         FIGS.  16 A and  16 B  are views corresponding to  FIGS.  2 A and  2 B , illustrating a fourteenth embodiment of the present disclosure and separately illustrating the top plate and the core; 
         FIGS.  17 A and  17 B  are views corresponding to  FIGS.  2 A and  2 B , illustrating a fifteenth embodiment of the present disclosure and separately illustrating the top plate and the core; and 
         FIG.  18    is an enlarged sectional view taken along the line D-D of  FIGS.  17 A and  17 B , schematically illustrating the top plate and the core, which are illustrated in  FIGS.  17 A and  17 B , fixed to each other with the adhesive interposed therebetween. 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIGS.  1 A and  1 B , the overview of a coil component  1  according to a first embodiment of the present disclosure is described. 
     As illustrated in  FIGS.  1 A and  1 B , the coil component  1  includes a core  2  made of, for example, a resin containing ferrite such as Ni—Zn-based ferrite, alumina, or magnetic metal powder. The core  2  includes a winding core portion  3  that extends in an axial direction AX and a first flange portion  5  and a second flange portion  6  that are provided at a first end and a second end, respectively, that are opposite ends in the axial direction AX of the winding core portion  3 . The cross-sectional shape of the winding core portion  3  is, for example, a rectangular shape but may be another shape such as a polygonal shape such as a hexagonal shape, a circular shape, an elliptical shape, or a shape obtained by combining them. 
     The first flange portion  5  and the second flange portion  6  have bottom surfaces  7  and  8  that face a mounting substrate (not illustrated) when the coil component  1  is mounted and top surfaces  9  and  10  on the opposite side of the respective bottom surfaces  7  and  8 , respectively. 
     A first terminal electrode  11  is provided on the bottom surface  7  of the first flange portion, and a second terminal electrode  12  is provided on the bottom surface  8  of the second flange portion  6 . The terminal electrodes  11  and  12  are formed by performing immersion or printing with a conductive paste containing conductive metal powder such as Ag powder, baking the resultant, and then sequentially performing Cu plating, Ni plating, and Sn plating, for example. Alternatively, the terminal electrodes  11  and  12  may be provided by mounting terminal members including conductive metal plates on the first and second flange portions  5  and  6 . 
     At least one wire  13  is wound around the winding core portion  3 . The wire  13  includes, for example, a central wire made of a metal with good conductivity such as copper, silver, or gold, and an insulating coating film covering the central wire and made of an electrical insulating resin such as polyamide imide, polyurethane, or polyester imide. The central wire has a diameter of 60 μm or more and 160 μm or less (i.e., from 60 μm to 160 μm), for example. One end of the wire  13  is connected to the first terminal electrode  11  on the side of the bottom surface  7  of the first flange portion  5  and the other end thereof is connected to the second terminal electrode  12  on the side of the bottom surface  8  of the second flange portion  6 . The terminal electrodes  11  and  12  and the wire  13  are connected to each other by thermocompression bonding, ultrasonic welding, or laser welding, for example. The number of turns of the wire  13  on the winding core portion  3  is optionally selected depending on required characteristics. The wire  13  may include turns in multiple layers as needed. 
     The coil component  1  includes a top plate  14  spanned between the first flange portion  5  and the second flange portion  6  described above. The top plate  14  has a lower main surface  15  and an upper main surface  16  that face directions opposite to each other. The top plate  14  is made of, for example, a resin containing ferrite, alumina, magnetic metal powder, or the like. Note that when the core  2  and the top plate  14  are both made of magnetic materials, the top plate  14  forms a closed magnetic circuit together with the core  2 . 
     The top plate  14  is fixed to the core  2  while the lower main surface  15  is facing the top surface  9  of the first flange portion  5  and the top surface  10  of the second flange portion  6  with an adhesive  17  interposed therebetween. The adhesive  17  contains a thermosetting resin such as an epoxy-based resin, for example. An inorganic filler such as a silica filler may be added to the adhesive  17  to improve the thermal shock resistance. 
     The coil component  1  has, for example, a dimension in the length direction (axial direction AX) of 2.0 mm, a dimension in a width direction (a direction vertical to the axial direction AX and in parallel with the mounting surface) of 1.2 mm, and a dimension in a height direction (a direction vertical to the axial direction AX and the width direction) of 1.6 mm. It is also conceivable that the coil component 1 is reduced in size to have a dimension in the length direction of 1.6 mm, a dimension in the width direction of 0.8 mm, and a dimension in the height direction of 1.3 mm. The smaller the coil component  1 , the larger the effect according to the present disclosure due to the precision of assembly equipment. Note that the planar dimensions of the top plate  14  are generally equivalent to the planar dimensions of the core  2 , and  FIGS.  1 A and  1 B  and  FIGS.  2 A and  2 B  illustrate the top plate  14  and the core  2  having the equivalent planar dimensions. The planar dimensions of the top plate  14  may, however, be larger than the planar dimensions of the core  2 . With the top plate  14  having planar dimensions larger than the planar dimensions of the core  2 , magnetic flux can positively pass through the top plate  14  even when the positions of the top plate  14  and the core  2  are slightly shifted from each other. 
     The coil component  1  is preferably manufactured as follows, for example. 
     First, the core  2  and the top plate  14  are each prepared. To manufacture each of the core  2  and the top plate  14 , for example, ferrite powder is subjected to press forming with a mold and the obtained compact is fired to obtain a sintered compact that is to serve as the core  2  or the top plate  14 . After that, the sintered compact that is to serve as the core  2  or the top plate  14  is subjected to barrel polishing to remove the burrs. Each of the core  2  and the top plate  14  is obtained in this way. Although not illustrated in  FIGS.  1 A and  1 B , the core  2  and the top plate  14  each have a rounded ridge line round-chamfered a little. 
     Then, to provide the terminal electrodes  11  and  12  to the core  2 , for example, a conductive paste containing Ag is applied to the bottom surfaces  7  and  8  of the first flange portion  5  and the second flange portion  6  to be baked, and then Cu plating, Ni plating, and Sn plating are sequentially performed by electrolytic barrel plating. 
     Next, the wire  13  is wound around the winding core portion  3  of the core  2  through nozzles, for example, and one end and the other end of the wire  13  are connected to the first terminal electrode  11  and the second terminal electrode  12 , respectively. Here, the wire  13  and the terminal electrodes  11  and  12  are connected to each other by thermocompression bonding by a heater chip, for example. An excess portion of the wire  13  connected to the terminal electrodes  11  and  12  is cut and removed by a cutting blade. 
     Next, the top plate  14  is placed on the core  2  with the adhesive  17  interposed therebetween and the top plate  14  and the core  2  are thus fixed to each other. 
     The coil component  1  is completed as described above. 
     The coil component  1  has the following features. A description is made with reference to  FIGS.  2 A and  2 B , and  FIG.  3   . 
     Projections  21  are provided on the lower main surface  15  of the top plate  14 . On the other hand, recesses  22  for receiving the projections  21  described above are provided in the first top surface  9  of the first flange portion  5  and the second top surface  10  of the second flange portion  6  of the core  2 .  FIG.  2 A  illustrates the top plate  14  and  FIG.  2 B  illustrates the core  2 , and when the top plate  14  and the core  2  are combined, the top plate  14  and the core  2  are placed so that the surface of the top plate  14  appearing in  FIG.  2 A  and the surface of the core  2  appearing in  FIG.  2 B  face each other. In combining the top plate  14  and the core  2 , the top plate  14  illustrated in  FIG.  2 A  is placed on the core  2  illustrated in  FIG.  2 B  with the posture rotated by 180 degrees about the axis of rotation extending in the left-right direction in  FIGS.  2 A and  2 B . 
     In the present embodiment, the projections  21  are provided at a plurality of places on the lower main surface  15  of the top plate  14  in the form of spots and the recesses  22  are provided at a plurality of places on the first top surface  9  of the first flange portion  5  and the second top surface  10  of the second flange portion  6  in the form of spots. More specifically, the two recesses  22  are provided side by side in the width direction in each of the first top surface  9  of the first flange portion  5  and the second top surface  10  of the second flange portion  6  of the core  2 , and the two projections  21  are provided side by side in the width direction on each of the region facing the first top surface  9  of the first flange portion  5  and the region facing the second top surface  10  of the second flange portion  6  on the lower main surface  15  of the top plate  14 . 
     The projection  21  has an outer peripheral surface that forms at least a portion of a cone and the recess  22  has a conical inner peripheral surface. The projection  21  preferably has a frustoconical shape with the chamfered distal end. With this, the distal end of the projection  21  can be prevented from being chipped in manufacturing the coil component  1 . The frustoconical projection  21  has a height H of 25 μm or more and 65 μm or less (i.e., from 25 μm to 65 μm), for example. 
     The outer surface of the projection  21  and a wall surface that defines the recess  22  function as guide surfaces capable of guiding the projection  21  into the recess  22 . For example, in the cross section illustrated in  FIG.  3   , the projection  21  has a distal end portion smaller than the opening of the recess  22  in dimensions measured along the lower main surface  15  of the top plate  14 . On the other hand, the recess  22  has a facing-inward sloped surface  23  inclined to reduce the dimensions of the recess  22  measured along the top surfaces  9  and  10  of the flange portions  5  and  6  from the opening toward the bottom. The facing-inward sloped surface  23  forms the guide surface described above. Further, for example, in the cross section illustrated in  FIG.  3   , the projection  21  has a facing-outward sloped surface  24  inclined to increase the dimensions of the projection  21  measured along the lower main surface  15  of the top plate  14  from the distal end portion of the projection  21  toward the base thereof that is a portion in contact with the lower main surface  15 . The facing-outward sloped surface  24  forms the guide surface described above. 
     The outer surface of the projection  21  and the wall surface that defines the recess  22  form a first abutment portion  25  and a second abutment portion  26 , respectively, that are brought into abutment against each other when the recess  22  receives the projection  21 . More specifically, a ridge line portion at which the chamfered distal end surface at the distal end portion and the outer peripheral surface of the projection  21  intersect each other forms the first abutment portion  25  and a portion of the facing-inward sloped surface  23  of the recess  22  forms the second abutment portion  26 . 
     In the cross section illustrated in  FIG.  3   , with respect to the extending direction of the lower main surface  15  of the top plate  14 , the facing-outward sloped surface  24  corresponding to the outer peripheral surface of the projection  21  has a larger angle than the facing-inward sloped surface  23  corresponding to the inner peripheral surface of the recess  22 . With this configuration, the inner peripheral surface of the recess  22  (facing-inward sloped surface  23 ) can be formed over a relatively large range, and hence the positioning effect is positively exhibited even with a relatively large positional shift between the projection  21  and the recess  22 . 
     The abutment between the first abutment portion  25  and the second abutment portion  26  defines the termination end of the projection  21  inserted into the recess  22  with a gap GP formed between the lower main surface  15  of the top plate  14  and the top surfaces  9  and  10  of the respective first and second flange portions  5  and  6  included in the core  2 , thereby achieving positioning in the direction of the insertion described above and achieves the alignment of the top plate  14  relative to the core  2  in at least one of directions along the lower main surface  15  and the top surfaces  9  and  10 . 
     More specifically, even when the facing positions of the projection  21  and the recess  22  are shifted from each other, since at least one of the outer surface of the projection  21  and the wall surface that defines the recess  22  is provided with the guide surface capable of guiding the projection  21  into the recess  22 , the facing positions of the projection  21  and the recess  22  can be matched with each other by the guide surface guiding the projection  21 . 
     A direction in which positioning or alignment is achieved is at least one of the directions along the lower main surface  15  and the top surfaces  9  and  10  as described above. Positioning in the length direction (axial direction AX) or the width direction (left-right direction in  FIG.  1 B ) of the coil component  1  is preferably achieved, and positioning in the length direction is more preferably achieved. This is because, since the length direction corresponds to the direction of magnetic flux in the coil component  1 , the inductance value relatively largely varies when the core  2  and the top plate  14  have a positional shift in the length direction. Note that in the case of the projection  21  and the recess  22  illustrated in  FIG.  3   , the positioning of the top plate  14  relative to the core  2  in all directions along the lower main surface  15  and the top surfaces  9  and  10  is achieved. 
     The adhesive  17  is applied to at least a portion of, preferably, the entire region of the gap GP described above, and the top plate  14  and the core  2  are thus fixed to each other with the adhesive  17  interposed therebetween. 
     Note that, in the structure illustrated in  FIG.  3   , since the distal end of the projection  21  and the inner peripheral surface of the recess  22  form the first abutment portion  25  and the second abutment portion  26 , the distal end portion of the projection  21  is not in contact with the bottom surface of the recess  22 . That is, only the ridge line portion at the periphery of the distal end portion of the projection  21  is in contact with the inner peripheral surface of the recess  22  so that the adhesive  17 , which is a resin, can be poured between the projection  21  and the recess  22  and the connection strength between the core  2  and the top plate  14  can therefore be improved. 
     In summary, the following configuration is realized with the projection  21  and the recess  22  having the forms as described above. 
     At least one of the outer surface of the projection  21  and the wall surface that defines the recess  22  is provided with the guide surface capable of guiding the projection  21  into the recess  22 . The outer surface of the projection  21  and the wall surface that defines the recess  22  form the first abutment portion  25  and the second abutment portion  26 , respectively, that are brought into abutment against each other when the recess  22  receives the projection  21 . The abutment between the first abutment portion  25  and the second abutment portion  26  defines the termination end of the projection  21  inserted into the recess  22  with the gap GP formed between the lower main surface  15  of the top plate  14  and the top surfaces  9  and  10  of the flange portions  5  and  6 , thereby achieving positioning in the direction of the insertion and achieves alignment in at least one of the directions along the lower main surface  15  of the top plate  14  and the top surfaces  9  and  10  of the flange portions  5  and  6 . 
     Next, with reference to  FIG.  4    and the following drawings, other embodiments of the present disclosure are described. In  FIG.  4    and the following drawings, elements corresponding to the elements illustrated in  FIGS.  2 A and  2 B  or  FIG.  3    are denoted by similar reference characters to omit a redundant description. The other embodiments are described in terms only of portions substantially different from the embodiment illustrated in  FIGS.  2 A and  2 B  and  FIG.  3   , or of features. 
     With reference to  FIG.  4   , in a second embodiment, although the recess  22  has a conical inner peripheral surface, the cavity formed by the recess  22  has a frustoconical shape. With this, a mold for molding the recess  22  can be prevented from being chipped. 
     In a third embodiment illustrated in  FIG.  5   , the cavity formed by the recess  22  has a frustoconical shape as in the structure illustrated in  FIG.  4   . On the other hand, although the projection  21  has a frustoconical shape, the inclination of the outer peripheral surface of the projection  21  is equal to the inclination of the inner peripheral surface of the recess  22 . With this configuration, the stability of the coupling state between the top plate  14  and the core  2  can be increased. 
     In a fourth embodiment illustrated in  FIG.  6   , the cavity formed by the recess  22  has a frustoconical shape. On the other hand, the projection  21  has a cylindrical portion  27  and a frustoconical portion  28 , and the cylindrical portion  27  is located on the base side and the frustoconical portion  28  is located on the distal end portion side. The inclination of the outer peripheral surface of the frustoconical portion  28  of the projection  21  is equal to the inclination of the inner peripheral surface of the recess  22 . 
     In a fifth embodiment illustrated in  FIG.  7   , the projection  21  has a frustoconical shape. On the other hand, the cavity formed by the recess  22  has a cylindrical shape. In one of cross sections along the direction in which positioning is achieved, for example, in the cross section of  FIG.  7   , the projection  21  has the facing-outward sloped surface  24  inclined to increase the dimensions of the projection  21  measured along the lower main surface  15  of the top plate  14  from the distal end portion toward the base. The facing-outward sloped surface  24  forms the guide surface capable of guiding the projection  21  into the recess  22 . Further, of the first abutment portion  25  and the second abutment portion  26  that are brought into abutment against each other when the recess  22  receives the projection  21 , the first abutment portion  25  is formed by the facing-outward sloped surface  24  of the projection  21  and the second abutment portion  26  is formed by an edge portion that defines the opening of the recess  22 . 
     With the structure illustrated in  FIG.  7   , a wide space can be secured between the projection  21  and the core  2  to allow the application of a sufficient amount of the adhesive  17 , and the coupling between the core  2  and the top plate  14  can therefore be strengthened. 
     Note that, in a modification of the fifth embodiment illustrated in  FIG.  7   , the projection  21  may have a conical shape and the recess  22  may be formed as a deeper recess to prevent the distal end of the projection  21  from being in contact with the bottom of the recess  22 . 
     A sixth embodiment illustrated in  FIG.  8    is different from the structure illustrated in  FIG.  7    in shape of the recess  22 . In  FIG.  8   , the edge portion that defines the opening of the recess  22  is chamfered to form the facing-inward sloped surface  23 . The facing-inward sloped surface  23  forms, together with the facing-outward sloped surface  24  formed by the outer peripheral surface of the projection  21 , the guide surfaces capable of guiding the projection  21  into the recess  22 . Further, of the first abutment portion  25  and the second abutment portion  26  that are brought into abutment against each other when the recess  22  receives the projection  21 , the first abutment portion  25  is formed by the facing-outward sloped surface  24  of the projection  21  and the second abutment portion  26  is formed by the facing-inward sloped surface  23  along the edge portion that defines the opening of the recess  22 . In this case, the first abutment portion  25  and the second abutment portion  26  are in contact with each other over a relatively large area. 
     In a seventh embodiment illustrated in  FIG.  9   , in one of the cross sections along the direction in which positioning is achieved, for example, in the cross section of  FIG.  9   , the recess  22  has a concave bottom surface  29  and only the distal end portion of the projection  21  is in abutment against the concave bottom surface  29 . Of the first abutment portion  25  and the second abutment portion  26  that are brought into abutment against each other when the recess  22  receives the projection  21 , the first abutment portion  25  is formed by the distal end portion of the projection  21  and the second abutment portion  26  is formed by the concave bottom surface  29 . Further, the outer surface of the projection  21  and the wall surface that defines the recess  22  form the guide surfaces capable of guiding the projection  21  into the recess  22 . 
     In the structure illustrated in  FIG.  9   , a magnetic path is formed due to the contact between the core  2  and the top plate  14 , thereby affecting the DC superimposition characteristics. Thus, according to the seventh embodiment illustrated in  FIG.  9   , the contact area between the core  2  and the top plate  14  can be adjusted by changing the shape of the concave bottom surface  29  so that the effect on the DC superimposition characteristics can be easily adjusted. 
       FIGS.  10 A and  10 B  are views corresponding to  FIGS.  2 A and  2 B , separately illustrating the top plate  14  and the core  2  that are employed in an eighth embodiment. 
     In the eighth embodiment illustrated in  FIGS.  10 A and  10 B , the projections  21  provided on the lower main surface  15  of the top plate  14  have an outer peripheral surface that forms a quadrangular pyramid and the recesses  22  for receiving the projections  21 , the recesses  22  being provided in the top surfaces  9  and  10  of the flange portions  5  and  6 , have an inner peripheral surface that forms a quadrangular pyramid. The projection  21  preferably has a quadrangular truncated pyramid shape with the chamfered distal end. With this, the distal end of the projection  21  can be prevented from being chipped in manufacturing the coil component  1 . 
     What is important in the eighth embodiment illustrated in  FIGS.  10 A and  10 B  is to indicate that the planar shapes of the projections  21  and the recesses  22  provided in the form of spots may be variously changed. 
       FIGS.  11 A and  11 B  are views corresponding to  FIGS.  2 A and  2 B , separately illustrating the top plate  14  and the core  2  that are employed in a ninth embodiment. 
     In the ninth embodiment illustrated in  FIGS.  11 A and  11 B , the projections  21  are provided on the top surfaces  9  and  10  of the flange portions  5  and  6  included in the core  2  and the recesses  22  are provided in the lower main surface  15  of the top plate  14 . The structure illustrated in  FIGS.  11 A and  11 B  indicates that the positional relationship of the projection  21  and the recess  22  may be reversed. 
     Note that, in terms of the ease of manufacturing, more specifically, the ease of molding of each of the core  2  and the top plate  14  and the simplification of the shape of the mold, the projections  21  are preferably provided on the top plate  14  having a simpler shape. However, when the recesses  22  are provided in the top plate  14  as illustrated in  FIGS.  11 A and  11 B , the adhesive can be held on the top plate  14  having the recesses  22  to prevent the adhesive from adhering to the wire through the core  2  in coupling the top plate  14  and the core  2  to each other. 
     In a modification of the ninth embodiment illustrated in  FIGS.  11 A and  11 B , some of the plurality of projections  21  may be provided on the top plate  14  and the remaining may be provided on the core  2 , and the recesses  22  may be separately provided in the core  2  and the top plate  14  so as to correspond to the projections  21 . 
     In a tenth embodiment illustrated in  FIGS.  12 A and  12 B , the projections  21  linearly extend on the lower main surface  15  of the top plate  14  and the recesses  22  for receiving the projections  21  linearly extend on the top surfaces  9  and  10  of the flange portions  5  and  6  included in the core  2 . The projections  21  and the recesses  22  extend in the width direction of the coil component. Although the cross-sectional shapes of the projection  21  and the recess  22  are not illustrated, cross-sectional shapes similar to the cross-sectional shapes illustrated in each of  FIGS.  3 A  to  FIG.  9    described above can be employed. 
     In an eleventh embodiment illustrated in  FIGS.  13 A and  13 B , as in the embodiment illustrated in  FIGS.  12 A and  12 B , the projections  21  linearly extend on the lower main surface  15  of the top plate  14  and the recesses  22  for receiving the projections  21  linearly extend on the top surfaces  9  and  10  of the flange portions  5  and  6  included in the core. The projections  21  and the recesses  22  extend, however, in the length direction of the coil component. Also in  FIGS.  13 A and  13 B , the cross-sectional shapes of the projection  21  and the recess  22  are not illustrated, but cross-sectional shapes similar to the cross-sectional shapes illustrated in each of  FIGS.  3 A  to  FIG.  9    described above can be employed. 
     In a twelfth embodiment illustrated in  FIGS.  14 A and  14 B , the embodiment illustrated in  FIGS.  12 A and  12 B  and the eleventh embodiment illustrated in  FIGS.  13 A and  13 B  are combined. That is, a projection  21   a  linearly extending in the width direction of the coil component and projections  21   b  linearly extending in the length direction of the coil component are provided on the lower main surface  15  of the top plate  14 , and a recess  22   a  linearly extending in the width direction of the coil component and recesses  22   b  linearly extending in the length direction of the coil component are provided in the top surfaces  9  and  10  of the flange portions  5  and  6  included in the core  2  so as to correspond to the projections  21   a  and  21   b.  Also in  FIGS.  14 A and  14 B , the cross-sectional shapes of the projection  21  and the recess  22  are not illustrated, but cross-sectional shapes similar to the cross-sectional shapes illustrated in each of  FIGS.  3 A  to  FIG.  9    described above can be employed. 
     In a thirteenth embodiment illustrated in  FIGS.  15 A and  15 B , the top plate  14  employs the form of the top plate  14  illustrated in  FIG.  2 A  and the core  2  employs the form of the core  2  illustrated in  FIG.  12 B . What is important in the present embodiment is to indicate that the combination of the projections  21  in the form of spots and the linear recesses  22  may be employed to realize the positioning function, more specifically, to form the guide surfaces and the first and second abutment portions. 
     In a fourteenth embodiment illustrated in  FIGS.  16 A and  16 B , a condition that may arise in the embodiment illustrated in  FIGS.  12 A and  12 B  can be addressed. That is, when the projections  21  reach the periphery of the lower main surface  15  of the top plate  14  and the recesses  22  reach the periphery of each of the top surfaces  9  and  10  of the flange portions  5  and  6  as in the embodiment illustrated in  FIGS.  12 A and  12 B , the space that is filled with the adhesive  17  (see  FIGS.  3 A and  3 B  or the like) forms relatively large openings in the outer surface of the coil component. Thus, a relatively large amount of the adhesive  17  may ooze out. 
     To address the condition described above, in the fourteenth embodiment illustrated in  FIGS.  16 A and  16 B , the projections  21  are located to be prevented from reaching the periphery of the lower main surface  15  of the top plate  14  and the recesses  22  are located to be prevented from reaching the periphery of each of the top surfaces  9  and  10  of the flange portions  5  and  6 . 
     In the first to ninth embodiments described with reference to  FIGS.  1 A  to  FIG.  11 B , a plurality of sets, more specifically, two sets of the projections  21  and the recesses  22  are provided to each of the region in which the lower main surface  15  of the top plate  14  and the top surface  9  of the first flange portion  5  face each other and the region in which the lower main surface  15  of the top plate  14  and the top surface  10  of the second flange portion  6  face each other. Then, the plurality of sets of the projections  21  and the recesses  22  are placed at symmetrical positions with respect to a surface that includes the central axis line of the winding core portion  3  and is orthogonal to the lower main surface  15  of the top plate  14 . Moreover, the plurality of sets of the projections  21  and the recesses  22  are placed at symmetrical positions with respect to a surface that is orthogonal to the central axis line of the winding core portion  3  and passes through the middle point in the axial direction AX of the winding core portion  3 . 
     The configuration described above offers an advantage that the posture of the top plate  14  relative to the core  2  can be kept stable. In the present disclosure, however, conditions for the selection of the numbers and placement of the projections  21  and the recesses  22  do not necessarily include obtaining such an advantage. 
     Further, to keep the posture of the top plate  14  relative to the core  2  stable, as in a fifteenth embodiment illustrated in  FIGS.  17 A and  17 B  and  FIG.  18   , a configuration other than the sets of the projections  21  and the recesses  22  can also be employed in combination with the configuration of the sets of the projections  21  and the recesses  22 . 
     In the fifteenth embodiment illustrated in  FIGS.  17 A and  17 B  and  FIG.  18   , in addition to the configuration of the sets of the projections  21  and the recesses  22 , there are second projections  31  facing the portions of the top surfaces  9  and  10  of the flange portions  5  and  6  in which no recess is provided. The second projections  31  are in abutment against the top surfaces  9  and  10  of the flange portions  5  and  6  with the gap GP formed between the lower main surface  15  of the top plate  14  and the top surfaces  9  and  10  of the flange portions  5  and  6 . 
     In the embodiment described above, with the sets of the projections  21  and the recesses  22 , the positioning of the top plate  14  relative to the core  2  in the directions along the lower main surface  15  of the top plate  14  and the top surfaces  9  and  10  of the flange portions  5  and  6  can be achieved, and with the sets of the projections  21  and the recesses  22  and the second projections  31 , the gap can be formed between the lower main surface  15  of the top plate  14  and the top surfaces  9  and  10  of the flange portions  5  and  6 . 
     In the embodiments described above, as illustrated in  FIGS.  1 A and  1 B  and described above, one end of the wire  13  is connected to the first terminal electrode  11  on the side of the bottom surface  7  of the first flange portion  5  and the other end thereof is connected to the second terminal electrode  12  on the side of the bottom surface  8  of the second flange portion  6 . With such a configuration, the end portions of the wire  13  are not necessarily located at the coupling portions between the core  2  and the top plate  14  so that the positions of the projection  21  and the recess  22  can be freely selected. 
     Although the present disclosure is described above in relation to the illustrated embodiments, other various modifications can be made within the scope of the present disclosure. 
     For example, the coil component to which the present disclosure is directed may form a common mode choke coil, a transformer, a balun, or the like other than a single coil as in the illustrated embodiments. Thus, the number of wires may be changed depending on the function of the coil component and the number of terminal electrodes provided on each flange portion may also be changed accordingly. 
     Further, in configuring the coil component according to the present disclosure, the components of different ones of the embodiments described herein can be partially replaced or combined.