Patent Publication Number: US-2021166861-A1

Title: Coil device

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a winding-type coil device. 
     As a winding-type coil device, for example, a coil device shown in Patent Document 1 is known. In the conventional winding-type coil device of Patent Document 1, metal terminals are attached to flanges of a magnetic core using adhesive or so, and an end of a wire constituting a coil is connected at a location dented from a mounting surface of the metal terminal. 
     When such a coil device with a conventional structure is used for power supply applications, however, the mounting surface of the metal terminal and a connection part of the wire end are away from each other. Thus, there is a problem with increase in DC resistance. 
     Patent Document 1: JP2018056399 (A) 
     BRIEF SUMMARY OF INVENTION 
     The present invention has been achieved under such circumstances. It is an object of the invention to provide a coil device having a low DC resistance and being capable of also being used for power supply applications. 
     To achieve the above object, a coil device according to the present invention includes: 
     a winding core made of a magnetic material and including a flange; 
     a wire wound around the winding core; and 
     a terminal fitting attached to a part of an outer surface of the flange, 
     wherein 
     the terminal fitting includes:
         a contact part contacted with the outer surface of the flange; and   a protrusion plate part formed integrally with the contact part and protruding away from the flange, and       

     the protrusion plate part includes:
         a wire connection surface to which a lead end of the wire is connected; and   a main mounting surface located opposite to the wire connection surface and being connectable to an external circuit.       

     In the coil device according to the present invention, the main mounting surface connected to an external circuit and the wire connection surface for the lead end of the wire are mutually located on the other side of the protrusion plate part. Thus, the wire connection surface and the main mounting surface are substantially close to each other only with the thickness of the protrusion plate part, and it is possible to extremely reduce a DC resistance of the terminal fitting from the connection part of the lead end of the wire to an external circuit board and is also possible to extremely reduce a DC resistance of the coil device as a whole. Thus, the coil device according to the present invention can favorably be used for power supply applications. 
     Even when the coil device according to the present invention is used for signal system applications, the increase in insertion loss (IL) can be restrained, and the coil device according to the present invention can also favorably be used for signal system applications. 
     Preferably, the protrusion plate part includes a base part continuing to the contact part and protruding from the flange and a tip bending part bending in turn back manner at a tip of the base part, and a lead end of the wire is sandwiched between the tip bending part and the base part. 
     When the lead end of the wire is sandwiched between the tip bending part and the base part, the lead end is easily connected to the terminal fitting. 
     The wire connection surface or the main mounting surface may be formed on a front surface or a rear surface of the tip bending part. Instead, the wire connection surface or the main mounting surface is formed on a front surface or a rear surface of the base part corresponding to the tip bending part. Instead, the protrusion plate part may not include the tip bending part. 
     Preferably, a sub-mounting surface being flush with the main mounting surface or located on an inner side of the main mounting surface is formed on a part of an outer surface of the contact part. This structure improves the mounting strength of the coil device and makes it easy to stably mount the coil device on a circuit board or so. 
     Preferably, a gap distance between the protrusion plate part and the flange in a perpendicular direction to the main mounting surface is twice or larger than a thickness of the protrusion plate part at a location where the lead end of the wire is connected to the protrusion plate part. In this structure, for example, the lead end of the wire can easily be connected to the protrusion plate part by laser welding or so. In addition, a thermal deformation stress of a circuit board or so is hard to travel to the flange, and the connection strength of the coil device to the circuit board is improved. 
     A plate-like member may be bonded on the outer surface of the flange located opposite to the main mounting surface. The plate-like member may be a magnetic member or a nonmagnetic member. In addition, the plate-like member may be a member formed by application of resin. Preferably, such plate-like members have a flat surface. A suction member for pickup can detachably be attached to the flat surface. This improves the handling performance. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a perspective view of a coil device according to an embodiment of the present invention; 
         FIG. 1B  is a lateral view of the coil device shown in  FIG. 1A ; 
         FIG. 1C  is a front view of the coil device shown in  FIG. 1A ; 
         FIG. 1D  is a bottom view of the coil device shown in  FIG. 1A ; 
         FIG. 2  is a perspective view of a drum-type core of the coil device shown in  FIG. 1A ; 
         FIG. 3  is a perspective view of a terminal metal fitting of the coil device shown in  FIG. 1A ; 
         FIG. 4A  is a perspective view of a coil device according to another embodiment of the present invention; 
         FIG. 4B  is a perspective view of a coil device according to a modified example of  FIG. 4A ; 
         FIG. 5  is a perspective view of a terminal metal fitting of the coil device shown in  FIG. 4A ; 
         FIG. 6A  is a perspective view of a terminal bracket used for a coil device according to further another embodiment of the present invention; 
         FIG. 6B  is a perspective view of a terminal metal fitting used for a coil device according to further another embodiment of the present invention; and 
         FIG. 6C  is a perspective view of a terminal metal fitting used for a coil device according to further another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     Hereinafter, the present invention is explained based on the embodiments shown in the figures. 
     First Embodiment 
     A coil device  10  according to an embodiment of the present invention shown in  FIG. 1A  is used for any purposes and is used as, for example, a winding-type common mode filter. The coil device  10  can also be used as a balun, a dual inductor, etc. 
     The coil device  10  includes a drum core  20 , a coil unit  40  wound around a winding core  22  of the drum core  20 , and a flat plate-like member  30  disposed on the drum core  20 . In the explanation of the coil device  10 , the X-axis direction is a direction parallel to a main mounting surface for the coil device  10  and to the winding axis of the winding core  22  of the drum core  20 , the Y-axis direction is a direction parallel to the main mounting surface as similarly to the X-axis and perpendicular to the X-axis, and the Z-axis is a normal direction of the main mounting surface. 
     As shown in  FIG. 2 , the drum core  20  includes the winding core  22  having a bar shape extending in the X-axis direction and a first flange  24  and a second flange  26  as a pair of core ends arranged on both ends of the winding core  22 . The first flange  24  and the second flange  26  have substantially the same shape and are arranged in the winding core  22  so as to substantially be parallel to each other with a predetermined space in the X-axis direction. 
     The winding core  22  is connected to a substantially central area of each of surfaces of the pair of flanges  24  and  26  facing each other and is integrated with the pair of flanges  24  and  26 . In the present embodiment, the winding core  22  has a rectangular cross-sectional shape, but may have any cross-sectional shape, such as circular. 
     Preferably, a plate-like member  30  shown in  FIG. 1A  is attached to an upper end of the drum core  20  in the Z-axis direction. Preferably, the plate-like member  30  is attached to an anti-mounting-side core surface  24   b  of the first flange  24  and an anti-mounting-side core surface  26   b  of the second flange  26  so as to bridge these anti-mounting-side core surfaces. 
     In the present embodiment, as shown in  FIG. 2 , the first flange  24  is structured by a rectangular parallelepiped as a whole, and rectangular notches  24   c   3  are formed at the lower ends of the rectangular parallelepiped shape on both sides in the Y-axis direction. The first flange  24  includes a mounting-side core surface  24   a  (lower surface in the Z-axis direction), the anti-mounting-side core surface  24   b  located opposite to the mounting-side core surface  24   a , an outer end surface  24   c  in the X-axis direction, an inner surface  24   d  facing the winding core  22 , and a pair of lateral surfaces  24   e  and  24   e  located opposite to each other in the Y-axis direction. 
     Terminal attachment surfaces  24   c   1  dented inward in the X-axis direction (toward the center of the core  20 ) from the outer end surface  24   c  are formed at the lower parts of the outer end surface  24   c  on both sides in the Y-axis direction. A terminal insulation projection  24   c   2  is formed between the terminal attachment surfaces  24   c   1  in the Y-axis direction and insulates a first terminal (terminal fitting)  51  and a second terminal (terminal fitting)  52  attached as shown in  FIG. 1A . An inner surface of an outer-end-surface contact portion  51   a   1  of a terminal body  51   a  of the first terminal  51  and an inner surface of an outer-end-surface contact portion  52   a   1  of a terminal body  52   a  of the second terminal  52  shown in  FIG. 3  are attached (or bonded as necessary) on the terminal attachment surfaces  24   c   1  shown in  FIG. 2 . 
     The step depth of the terminal attachment surfaces  24   c   1  dented from the outer end surface  24   c  shown in  FIG. 2  toward the inner side in the X-axis direction is preferably as large as a plate thickness of the first terminal  51  or the second terminal  52  shown in  FIG. 3 , but may be smaller or larger than the plate thickness. The shape of the first terminal  51  and the shape of the second terminal  52  shown in  FIG. 3  are line-symmetric to each other. 
     The first terminal  51  is structured by a conductive terminal plate or so and includes the terminal body  51   a  and a protrusion plate part  51   b  formed by bending a sheet of conductive plate-like member of a metal plate or so. The terminal body  51   a  includes the outer-end-surface contact portion  51   a   1  with a substantially L shape attached to one terminal attachment surface  24   c   1  formed on the outer end surface  24   c  of the flange  24  shown in  FIG. 2  using adhesive or so. In addition, the terminal body  51   a  includes a mounting-side contact portion  51   a   2  with a rectangular plate shape formed by bending from the lower end of the outer-end-surface contact portion  51   a   1  in the Z-axis direction to the X-axis direction. 
     The outer-end-surface contact portion  51   a   1  of the terminal body  51   a  shown in  FIG. 3  is fixed to the terminal attachment surface  24   c   1  of the flange  24  shown in  FIG. 2  using adhesive or so. The mounting-side contact portion  51   a   2  shown in  FIG. 3  is contacted with the mounting-side core surface  24   a  shown in  FIG. 2  with a predetermined space (or no space). The outer surface of the mounting-side contact portion  51   a   2  located opposite to the surface contacted with the mounting-side core surface  24   a  shown in  FIG. 2  is a sub-mounting surface  51   a   3 . The role of the sub-mounting surface  51   a   3  is mentioned below. 
     The protrusion plate part  51   b  shown in  FIG. 3  and protruding outward in the Y-axis direction from the mounting-side core surface  24   a  of the flange  24  at the lower end of the flange  24  shown in  FIG. 2  is formed integrally with the mounting-side contact portion  51   a   2  of the terminal body  51   a  shown in  FIG. 3 . The protrusion plate part  51   b  includes a base part  51   c  being flush with the mounting-side contact portion  51   a   2  of the terminal body  51   a  and extending outward in the Y-axis direction and a tip bending part  51   d  bending in turn back manner from the tip of the base part  51   c.    
     In the present embodiment, the tip bending part  51   d  bends upward in the Z-axis direction and turns back at the tip of the base part  51   c , the outer surface of the base part  51   c  located opposite to the tip bending part  51   d  is a main mounting surface  51   c   1 , and the inner surface of the base part  51   c , which the tip bending part  51   d  is located, is a connection surface (wire connection surface)  51   c   2 . As shown in  FIG. 1C , a lead end  41   a  (one lead end) of a first wire  41  (one wire) constituting the coil unit  40  shown in  FIG. 1B  is sandwiched and caulked by the connection surface  51   c   2  of the base part  51   c  and the tip bending part  51   d . After the caulking, the terminal  51  and the lead end  41   a  of the wire  41  may be connected by soldering, laser welding, etc. 
     In the present embodiment, as shown in  FIG. 1C , the main mounting surface  51   c   1  and the sub-mounting surface  51   a   3  of the first terminal  51  are outer surfaces being flush with each other, and the main mounting surface  51   c   1  is mainly connected to a circuit pattern of an external circuit board (not shown), but the sub-mounting surface  51   a   3  may also be connected to the circuit pattern at the same time. The connection to the circuit pattern of the external circuit board is carried out in any manner, such as solder connection. 
     As with the first terminal  51 , the second terminal  52  is structured by a conductive terminal plate or so and includes a terminal body  52   a  and a protrusion plate part  52   b  formed by bending a sheet of conductive plate-like member of a metal plate or so. The terminal body  52   a  includes the outer-end-surface contact portion  52   a   1  with a substantially L shape attached to the other terminal attachment surface  24   c   1  formed on the outer end surface  24   c  of the flange  24  shown in  FIG. 2  using adhesive or so. In addition, the terminal body  52   a  includes a mounting-side contact portion  52   a   2  with a rectangular plate shape formed by bending from the lower end of the outer-end-surface contact portion  52   a   1  in the Z-axis direction to the X-axis direction. 
     The outer-end-surface contact portion  52   a   1  of the terminal body  52   a  shown in  FIG. 3  is fixed to the terminal attachment surface  24   c   1  of the flange  24  shown in  FIG. 2  using adhesive or so. The mounting-side contact portion  52   a   2  shown in  FIG. 3  is contacted with the mounting-side core surface  24   a  shown in  FIG. 2  with a predetermined space (or no space). The outer surface of the mounting-side contact portion  52   a   2  located opposite to the surface contacted with the mounting-side core surface  24   a  shown in  FIG. 2  is a sub-mounting surface  52   a   3 . The role of the sub-mounting surface  52   a   3  is similar to that of the sub-mounting surface  51   a   3 . 
     The protrusion plate part  52   b  shown in  FIG. 3  and protruding outward in the Y-axis direction from the mounting-side core surface  24   a  of the flange  24  at the lower end of the flange  24  shown in  FIG. 2  is formed integrally with the mounting-side contact portion  52   a   2  of the terminal body  52   a  shown in  FIG. 3 . The protrusion plate part  52   b  includes a base part  52   c  being flush with the mounting-side contact portion  52   a   2  of the terminal body  52   a  and extending outward in the Y-axis direction and a tip bending part  52   d  bending in turn back manner from the tip of the base part  52   c.    
     In the present embodiment, the tip bending part  52   d  bends upward in the Z-axis direction and turns back at the tip of the base part  52   c , the outer surface of the base part  52   c  located opposite to the tip bending part  52   d  is a main mounting surface  52   c   1 , and the inner surface of the base part  52   c , which the tip bending part  52   d  is located, is a connection surface (wire connection surface)  52   c   2 . As shown in  FIG. 1C , a lead end  42   a  (one lead end) of a second wire  42  (the other wire) constituting the coil unit  40  shown in  FIG. 1B  is sandwiched and caulked by the connection surface  52   c   2  of the base part  52   c  and the tip bending part  52   d . After the caulking, the terminal  52  and the lead end  42   a  of the wire  42  may be connected by soldering, laser welding, etc. 
     In the present embodiment, as shown in  FIG. 1C , the main mounting surface  52   c   1  and the sub-mounting surface  52   a   3  of the second terminal  52  are outer surfaces being flush with each other, and the main mounting surface  52   c   1  is mainly connected to a circuit pattern of an external circuit board (not shown), but the sub-mounting surface  52   a   3  may also be connected to the circuit pattern at the same time. The connection to the circuit pattern of the external circuit board is carried out in any manner, such as solder connection. 
     In the present embodiment, the second flange  26  has a similar structure to the first flange  24 , but may not necessarily have the same structure. In the present embodiment, as shown in  FIG. 2 , the second flange  26  is structured by a rectangular parallelepiped as a whole, and rectangular notches  26   c   3  are formed at the lower ends of the rectangular parallelepiped on both sides in the Y-axis direction. The second flange  26  includes a mounting-side core surface  26   a  (lower surface in the Z-axis direction), the anti-mounting-side core surface  26   b  located opposite to the mounting-side core surface  26   a , an outer end surface  26   c  in the X-axis direction, an inner surface  26   d  facing the winding core  22 , and a pair of lateral surfaces  26   e  and  26   e  mutually located on the other side in the Y-axis direction. 
     Terminal attachment surfaces  26   c   1  dented inward in the X-axis direction (toward the center of the core  20 ) from the outer end surface  26   c  are formed on lower parts of the outer end surface  26   c  on both sides in the Y-axis direction. A terminal insulation projection (not shown; corresponding with the terminal insulation projection  24   c   2 ) is formed between the terminal attachment surfaces  26   c   1  in the Y-axis direction and insulates the first terminal  51  and the second terminal  52  on the back in the X-axis direction shown in  FIG. 3 . An inner surface of an outer-end-surface contact portion  51   a   1  of a terminal body  51   a  of the first terminal  51  and an inner surface of an outer-end-surface contact portion  52   a   1  of a terminal body  52   a  of the second terminal  52  shown in  FIG. 3  are attached (or bonded as necessary) on the terminal attachment surfaces  26   c   1  shown in  FIG. 2 . 
     The attachment structure of the first terminal  51  and the second terminal  52  on the back in the X-axis direction shown in  FIG. 3  to the second flange  26  shown in  FIG. 2  is similar to that to the first flange  24  shown in  FIG. 2  mentioned above and is thereby not explained in detail. 
     As shown in  FIG. 1C , the lead end  41   a  (one leading portion) of the first wire  41  is connected to the connection surface  51   c   2  of the first terminal  51 , and the lead end  42   a  (one leading portion) of the second wire  42  is connected to the connection surface  52   c   2  of the second terminal  52 . Moreover, the lead end  41   b  (the other leading portion) of the first wire  41  is connected to the connection surface  52   c   2  of the second terminal  52  on the back in the X-axis direction shown in  FIG. 3 , and the lead end  42   b  (the other leading portion) of the second wire  42  shown in  FIG. 1C  is connected to the connection surface  51   c   2  of the first terminal  51  on the back in the X-axis direction shown in  FIG. 3 . These are connected by any method, such as welding, resistance welding, ultrasonic welding, caulking, thermocompression bonding, and heat welding (preferably, laser welding, soldering, etc.). 
     As shown in  FIG. 1A ,  FIG. 1B , and  FIG. 1D , the coil unit  40  is formed around the winding core  22  of the drum core  20 . In the present embodiment, the coil unit  40  is structured by two wires  41  and  42 . The wires  41  and  42  are structured by, for example, a coated wire formed by covering a core made of a good conductor (e.g., copper wire) with an insulating coverage film and are wound around the winding core  22 , for example, in a double-layer structure. In the present embodiment, the cross-sectional areas of conductive parts of the wires  41  and  42  are the same as each other. 
     In the present embodiment, the first wire  41  and the second wire  42  are wound around the winding core  22  by a normal bifilar winding, but a cross part may be formed at a predetermined location in the winding axis of the winding core  22 . 
     In the manufacture of the coil device  10 , two pairs of terminals  51  and  52  shown in  FIG. 3  are initially attached to the drum core  20  shown in  FIG. 2 . Preferably, only the inner surfaces of the outer-end-surface contact portions  51   a   1  and  52   a   1  of the terminals  51  and  52  are bonded with the terminal attachment surfaces  24   c   1  or  26   c   1 . Preferably, the mounting-side contact portions  51   a   2  and  52   a   2  of the terminals  51  and  52  are not bonded with the mounting-side core surface  24   a  ( 26   a ) of the flange  24  ( 26 ). This is because a vibration of an external circuit board not shown is prevented from directly traveling to the mounting-side core surface  24   a  ( 26   a ) of the flange  24  ( 26 ). 
     Prepared are the drum-type drum core  20  with the terminals  51  and  52  manufactured in such a manner, the flat plate-like member  30 , and the wires  41  and  42 . The drum core  20  is made of magnetic material and can be manufactured by, for example, pressing and sintering a magnetic material with a comparatively high permeability (e.g., Ni—Zn based ferrite, Mn—Zn based ferrite) or a magnetic powder composed of metal magnetic material or so. The flat plate-like member  30  is preferably made of the same or different magnetic material from the drum core  20 , but is not necessarily made of magnetic material. 
     The terminals  51  and  52  are structured by a metal terminal made of phosphor bronze, tough pitch steel, pure copper, brass, silver, gold, metallic alloys with solder bondability, etc. Each of the terminals  51  and  52  has any thickness, but preferably has a thickness of 50-300 μm. 
     For example, the wires  41  and  42  can be formed by covering a core made of a good conductor of copper (Cu) or so with an insulating material made of imide-modified polyurethane or so and further covering the outermost surface with a thin resin film of polyester or so. The drum core  20  on which the terminals  51  and  52  are installed and the wires  41  and  42  are set to a winding machine, and the wires  41  and  42  are wound around the winding core  22  of the drum core  20  in a predetermined order. Each of the wires  41  and  42  has any diameter, but preferably has a diameter of 10-300 μm. 
     In the present embodiment, the first wire  41  and the second wire  42  are wound by bifilar winding. The lead ends  41   a ,  42   a ,  41   b , and  42   b  of the lead portions (wire ends) of the wound wires  41  and  42  are connected after the tip bending part  51   d  or  52   d  is caulked to the connection surface  51   c   2  or  52   c   2  of the predetermined terminals  51  and  52  shown in  FIG. 3 . 
     After the winding operation of the wires  41  and  42  to the winding core  22 , the flat plate-like member  30  is connected to the anti-mounting-side core surfaces  24   b  and  26   b  of the flanges  24  and  26  by any method, such as adhesion. 
     In the coil device  10  according to the present embodiment, the wire length of the lead end  41   a  (one lead portion) of the first wire  41  from the coil unit  40  to the connection surface  51   c   2  of the first terminal  51  and the wire length of the lead end  42   a  (one lead portion) of the second wire  42  from the coil unit  40  to the connection surface  52   c   2  of the second terminal  52  are preferably substantially the same, but may be different from each other. Preferably, the winding number of the first wire  41  and the winding number of the second wire  42  in the coil unit  40  are the same as each other. This structure further improves mode conversion characteristics. 
     In the coil device  10  according to the present embodiment, as shown in  FIG. 1C , the main mounting surface  51   c   1  ( 52   c   1 ) of the terminal  51  ( 52 ) and the connection surface  51   c   2  ( 52   c   2 ), which is a wire connection surface for the lead end  41   a  ( 42   a ) of the wire  41  ( 42 ), are mutually located on the other side of the base part  51   c  ( 52   c ). Thus, the connection surface  51   c   2  ( 52   c   2 ) and the main mounting surface  51   c   1  ( 52   c   1 ) are substantially close to each other only with the thickness of the base part  51   c  ( 52   c ) of the protrusion plate part  51   b  ( 52   b ), and it is possible to extremely reduce a DC resistance of the terminal  51  ( 52 ) from the connection part of the lead end  41   a  ( 42   a ) of the wire  41  ( 42 ) to an external circuit board (not shown). Thus, it is also possible to extremely reduce a DC resistance of the coil device  10  as a whole. 
     As a result, the coil device  10  according to the present embodiment can also favorably be used for power supply applications. Even when the coil device  10  according to the present embodiment is used for signal system applications, the increase in insertion loss (IL) can be restrained, and the coil device  10  according to the present embodiment can also favorably be used for a high frequency signal system application of, for example, 100 MHz or more. 
     In the present embodiment, the contact part of the terminal  51  ( 52 ) made of metal plate is partly contacted with a part of the flange  24  ( 26 ) of the drum core  20  (excluding the mounting-side core surface  24   a  ( 26   a )), and a vibration, a thermal deformation force, or the like from an external circuit board is thereby hard to directly travel to the drum core. As a result, the connection strength of the coil device  10  to an external circuit board is improved. 
     In the present embodiment, as shown in  FIG. 3 , the protrusion plate part  51   b  ( 52   b ) includes the base part  51   c  ( 52   c ) shown in  FIG. 3  continuing to the mounting-side contact portion  51   a   2  ( 52   a   2 ) of the terminal body  51   a  ( 52   a ) and protruding from the flange  24  ( 26 ) shown in  FIG. 2 . As shown in  FIG. 3 , the protrusion plate part  51   b  ( 52   b ) includes the tip bending part  51   d  ( 52   d ) bending in turn back manner at the tip side of the protrusion plate part  51   b  ( 52   b ). Then, as shown in  FIG. 1C , the lead end  41   a  ( 42   a ) ( 41   b ,  42   b ) of the wire  41  ( 42 ) is sandwiched and caulked between the base part  51   c  ( 52   c ) and the tip bending part  51   d  ( 52   d ). When the lead end  41   a  ( 42   a ) ( 41   b ,  42   b ) of the wire  41  ( 42 ) is sandwiched between the base part  51   c  ( 52   c ) and the tip bending part  51   d  ( 52   d ) in such a manner, the lead end  41   a  ( 42   a ) is easily connected to the terminal  51  ( 52 ). 
     In the present embodiment, the sub-mounting surface  51   a   3  ( 52   a   3 ) being flush with the main mounting surface  51   c   1  ( 52   c   2 ) or located on the inner side of the main mounting surface  51   c   1  ( 52   c   2 ) is formed on the outer surface of the mounting-side contact portion  51   a   2  ( 52   a   2 ) of the terminal  51  ( 52 ). This structure improves the mounting strength of the coil device  10  and makes it easy to stably mount the coil device  10  on a circuit board (not shown) or so. 
     In the present embodiment, as shown in  FIG. 1C , a gap distance Z 1  between the tip bending part  51   d  ( 52   d ) of the protrusion plate part  51   b  ( 52   b ) and the flange  24  ( 26 ) at a connection location of the lead end  41   a  ( 42   a ) of the wire  41  ( 42 ) in the Z-axis direction perpendicular to the main mounting surface  51   c   1  ( 52   c   2 ) is twice or larger than a thickness of the protrusion plate part  51   b  ( 52   b ). In this structure, for example, the lead end  41   a  ( 42   a ) of the wire  41  ( 42 ) can easily be connected to the protrusion plate part  51   b  ( 52   b ) by laser welding, soldering, or the like. In addition, a thermal deformation stress of a circuit board (not shown) or so is hard to travel to the flanges, and the connection strength of the coil device  10  to the circuit board is improved. 
     In the present embodiment, as shown in  FIG. 1A , the coil device  10  according to the present embodiment further includes the flat plate-like member  30  bridging the anti-mounting-side core surface  24   b  of the first flange  24  and the anti-mounting-side core surface  26   b  of the second flange  26 . When the flat plate-like member  30  is made of magnetic material, a closed magnetic circuit can be formed by combination with the drum core  20  made of magnetic material, and magnetic characteristics of the coil device  10  are improved. 
     Incidentally, the plate-like member  30  may be a nonmagnetic member. In addition, the plate-like member  30  may be a member formed by application of resin. Preferably, such plate-like members  30  have a flat surface. A suction member for pickup can detachably be attached to the flat surface. This improves the handling performance. 
     Second Embodiment 
     A coil device according to Second Embodiment of the present invention is different from the coil device  10  according to First Embodiment only in the following structure and demonstrates effects similar to those of First Embodiment. The overlapping matters with First Embodiment are not explained. In the figures, common components with First Embodiment are given common references. 
     In a coil device  110  according to the present embodiment, as shown in  FIG. 4A  and  FIG. 5 , the first terminal  51  and the second terminal  52  of the coil device  10  according to First Embodiment shown in  FIG. 1A  to  FIG. 3  are respectively replaced with a first terminal  151  and a second terminal  152 . 
     The first terminal  151  shown in  FIG. 5  is structured by a conductive terminal plate or so and includes a terminal body  151   a  and a protrusion plate part  151   b  formed by bending a sheet of conductive plate-like member of a metal plate or so. The terminal body  151   a  includes an outer-end-surface contact portion  151   a   1  attached to one terminal attachment surface  24   c   1  formed on the outer end surface  24   c  of the flange  24  shown in  FIG. 2  using adhesive or so. In addition, the terminal body  151   a  includes a mounting-side contact portion  151   a   2  with a rectangular plate shape formed by bending from the lower end of the outer-end-surface contact portion  151   a   1  in the Z-axis direction to the X-axis direction. 
     The outer-end-surface contact portion  151   a   1  of the terminal body  151   a  shown in  FIG. 5  is fixed to the terminal attachment surface  24   c   1  of the flange  24  shown in  FIG. 2  using adhesive or so. The mounting-side contact portion  151   a   2  shown in  FIG. 5  is contacted with the mounting-side core surface  24   a  shown in  FIG. 2  with a predetermined space (or no space). The outer surface of the mounting-side contact portion  151   a   2  located opposite to the surface contacted with the mounting-side core surface  24   a  shown in  FIG. 2  is a sub-mounting surface  151   a   3 . The role of the sub-mounting surface  151   a   3  is mentioned below. 
     A lateral contact portion  151   a   4  contacted with a lower part of the lateral surface  24   e  of the flange  24  shown in  FIG. 2  (see  FIG. 5 ) is formed integrally with an outer end of the outer-end-surface contact portion  151   a   1  of the terminal body  151   a  in the Y-axis direction shown in  FIG. 5 . As shown in  FIG. 5 , the protrusion plate part  151   b  protruding downward in the Z-axis direction from the lateral surface  24   e  of the flange  24  shown in  FIG. 2  is formed integrally with the terminal body  151   a  at a lower part of the lateral contact portion  151   a   4  in the Z-axis direction. 
     The protrusion plate part  151   b  includes a first base part  151   e  being flush with the lateral contact portion  151   a   4  of the terminal body  151   a  and extending downward in the Z-axis direction, a second base part  151   c  formed integrally and bending inward in the Y-axis direction from the lower end of the first base part  151   e  in the Z-axis direction, and a tip bending part  151   d  bending in turn back manner from the tip of the second base part  151   c.    
     In the present embodiment, the tip bending part  151   d  bends outward in the Y-axis direction and turns back at the tip of the second base part  151   c , the outer surface of the second base part  151   c  located opposite to the tip bending part  151   d  is a main mounting surface  151   c   1 , and the inner surface of the second base part  151   c , where the tip bending part  151   d  is located, is a connection surface (wire connection surface)  151   c   2 . As shown in  FIG. 4A , a lead end  41   a  (one lead end) of the first wire  41  (one wire) constituting the coil unit  40  is sandwiched and caulked by the connection surface  151   c   2  of the second base part  151   c  and the tip bending part  151   d . After the caulking, the terminal  151  and the lead end  41   a  of the wire  41  may be connected by soldering, laser welding, etc. 
     In the present embodiment, the main mounting surface  151   c   1  of the first terminal  151  protrudes downward in the Z-axis direction from the sub-mounting surface  151   a   3  by a predetermined distance Z 2 . Preferably, the predetermined distance Z 2  is larger than zero and is about four times or less (more preferably, twice or less) of the thickness of the plate-like member constituting the first terminal  151 . In the present embodiment, the main mounting surface  151   c   1  is mainly connected to a circuit pattern of an external circuit board (not shown), but the sub-mounting surface  151   a   3  may also be connected to the circuit pattern at the same time. The connection to the circuit pattern of the external circuit board is carried out in any manner, such as solder connection. 
     As with the first terminal  151 , the second terminal  152  shown in  FIG. 5  is also structured by a conductive terminal plate or so and includes a terminal body  152   a  and a protrusion plate part  152   b  formed by bending a sheet of conductive plate-like member of a metal plate or so. The terminal body  152   a  includes an outer-end-surface contact portion  152   a   1  attached to the other terminal attachment surface  24   c   1  formed on the outer end surface  24   c  of the flange  24  shown in  FIG. 2  using adhesive or so. In addition, the terminal body  152   a  includes a mounting-side contact portion  152   a   2  with a rectangular plate shape formed by bending from the lower end of the outer-end-surface contact portion  152   a   1  in the Z-axis direction to the X-axis direction. 
     The outer-end-surface contact portion  152   a   1  of the terminal body  152   a  shown in  FIG. 5  is fixed to the terminal attachment surface  24   c   1  of the flange  24  shown in  FIG. 2  using adhesive or so. The mounting-side contact portion  152   a   2  shown in  FIG. 5  is contacted with the mounting-side core surface  24   a  shown in  FIG. 2  with a predetermined space (or no space). The outer surface of the mounting-side contact portion  152   a   2  shown in  FIG. 5  and located opposite to the surface contacted with the mounting-side core surface  24   a  shown in  FIG. 2  is a sub-mounting surface  152   a   3 . The role of the sub-mounting surface  152   a   3  is similar to that of the sub-mounting surface  151   a   3 . 
     A lateral contact portion  152   a   4  contacted with a lower part of the lateral surface  24   e  of the flange  24  shown in  FIG. 2  (see  FIG. 5 ) is formed integrally with an outer end of the outer-end-surface contact portion  152   a   1  of the terminal body  152   a  in the Y-axis direction shown in  FIG. 5 . As shown in  FIG. 5 , the protrusion plate part  152   b  protruding downward in the Z-axis direction from the lateral surface  24   e  of the flange  24  shown in  FIG. 2  is formed integrally with the terminal body  152   a  at a lower part of the lateral contact portion  152   a   4  in the Z-axis direction. 
     The protrusion plate part  152   b  includes a first base part  152   e  being flush with the lateral contact portion  152   a   4  of the terminal body  152   a  and extending downward in the Z-axis direction, a second base part  152   c  formed integrally and bending inward in the Y-axis direction from the lower end of the first base part  152   e  in the Z-axis direction, and a tip bending part  152   d  bending in turn back manner from the tip of the second base part  152   c.    
     In the present embodiment, the tip bending part  152   d  bends outward in the Y-axis direction and turns back at the tip of the second base part  152   c , the outer surface of the second base part  152   c  located opposite to the tip bending part  152   d  is a main mounting surface  152   c   1 , and the inner surface of the second base part  152   c , where the tip bending part  152   d  is located, is a connection surface (wire connection surface)  152   c   2 . As shown in  FIG. 4A , a lead end  42   a  (one lead end) of the second wire  42  (the other wire) constituting the coil unit  40  is sandwiched and caulked by the connection surface  152   c   2  of the second base part  152   c  and the tip bending part  152   d . After the caulking, the terminal  152  and the lead end  42   a  of the wire  42  may be connected by soldering, laser welding, etc. 
     In the present embodiment, the main mounting surface  152   c   1  of the second terminal  152  protrudes downward in the Z-axis direction from the sub-mounting surface  152   a   3  by a predetermined distance Z 2 . In the present embodiment, the main mounting surface  152   c   1  is mainly connected to a circuit pattern of an external circuit board (not shown), but the sub-mounting surface  151   a   3  may also be connected to the circuit pattern at the same time. The connection to the circuit pattern of the external circuit board is carried out in any manner, such as solder connection. 
     The coil device  110  according to the present embodiment also demonstrates effects similar to those of the coil device  10  according to First Embodiment. In particular, in the coil device  110 , the second base part  151   c  ( 152   c ), where the main mounting surface  151   c   1  ( 152   c   1 ) of the terminal  151  ( 152 ) is formed, and the lateral contact portion  151   a   4  ( 152   a   4 ) are connected integrally by the first base part  151   e  ( 152   e ) (leaf spring-like support). Thus, even if an external circuit board (not shown) connected to the main mounting surface  151   c   1  ( 152   c   1 ) bends or vibrates due to external force, thermal deformation, or the like, the deformation of the first base part  151   e  ( 152   e ) absorbs the deformation (force) or the vibration and can effectively protect the coil device  110 . 
     Third Embodiment 
     A coil device according to Third Embodiment of the present invention is different from the coil device  110  according to Second Embodiment only in the following structure and demonstrates effects similar to those of Second Embodiment. The overlapping matters with Second Embodiment are not explained. In the figures, common components with First and Second Embodiments are given common references. 
     In a coil device  110 α according to the present embodiment, as shown in  FIG. 4B , a first terminal  151  and a second terminal  152  shown in  FIG. 4A  are respectively replaced with a first terminal  151 α and a second terminal  152 α. 
     The first terminal  151 α shown in  FIG. 4B  is structured by a conductive terminal plate or so and includes a terminal body  151   a  and a protrusion plate part  151   b  formed by bending a sheet of conductive plate-like member of a metal plate or so. The terminal body  151   a  includes the outer-end-surface contact portion  151   a   1  attached to one terminal attachment surface formed on the outer end surface  24   c  of the flange  24  shown in  FIG. 2  using adhesive or so. In addition, the terminal body  151   a  includes a mounting-side contact portion  151   a   2  with a rectangular plate shape formed by bending from the lower end of the outer-end-surface contact portion  151   a   1  in the Z-axis direction to the X-axis direction. 
     In the present embodiment, the lateral contact portion  151   a   4  shown in  FIG. 5  is not formed, and as shown in  FIG. 4B , the protrusion plate part  151   b  protruding downward in the Z-axis direction from an outer part of the outer-end-surface contact portion  151   a   1  in the Y-axis direction is formed integrally with the terminal body  151   a.    
     The protrusion plate part  151   b  includes a first base part  151   e  being flush with the outer-end-surface contact portion  151   a   1  of the terminal body  151   a  and extending downward in the Z-axis direction, a second base part  151   c  formed integrally and bending inward in the X-axis direction from the lower end of the first base part  151   e  in the Z-axis direction, and a tip bending part  151   d  bending in turn back manner from the tip of the second base part  151   c.    
     In the present embodiment, the tip bending part  151   d  bends outward in the X-axis direction and turns back at the tip of the second base part  151   c , the outer surface of the second base part  151   c  located opposite to the tip bending part  151   d  is a main mounting surface  151   c   1 , and the inner surface of the second base part  151   c , where the tip bending part  151   d  is located, is a connection surface (wire connection surface)  151   c   2 . As shown in  FIG. 4B , a lead end  41   a  (one lead end) of the first wire  41  (one wire) constituting the coil unit  40  is sandwiched and caulked by the connection surface  151   c   2  of the second base part  151   c  and the tip bending part  151   d . After the caulking, the terminal  151  and the lead end  41   a  of the wire  41  may be connected by soldering, laser welding, etc. 
     As with the first terminal  151 α , the second terminal  152 α shown in  FIG. 4B  is also structured by a conductive terminal plate or so and includes a terminal body  152   a  and a protrusion plate part  152   b  formed by bending a sheet of conductive plate-like member of a metal plate or so. The second terminal  152 α is structured in line-symmetric manner to the first terminal  151 αbased on the Z-axis and the X-axis. That is, the terminal body  152   a , the outer-end-surface contact portion  152   a   1 , the mounting-side contact portion  152   a   2 , the sub-mounting surface  152   a   3 , the protrusion plate part  152   b , the second base part  152   c , the main mounting surface  152   c   1 , the connection surface  152   c   2 , and the tip bending part  152   d  of the first terminal  151 α correspond with the terminal body  151   a , the outer-end-surface contact portion  151   a   1 , the mounting-side contact portion  151   a   2 , the sub-mounting surface  151   a   3 , the protrusion plate part  151   b , the second base part  151   c , the main mounting surface  151   c   1 , the connection surface  151   c   2 , and the tip bending part  151   d  of the second terminal  152 α, respectively. These overlapping components are not explained. 
     The coil device  110   a  according to the present embodiment also demonstrates effects similar to those of the coil device  110  according to Second Embodiment. 
     Fourth Embodiment 
     A coil device according to Fourth Embodiment of the present invention is different from the coil device according to First, Second, or Third Embodiment mentioned above only in the following structure and demonstrates effects similar to those of First, Second, or Third Embodiment. The overlapping matters with First, Second, or Third Embodiment are not explained. In the figures, common components with First to Third Embodiments are given common references. 
     As shown in  FIG. 6A , a first terminal  251  used for the coil device according to the present embodiment is a modified example of the first terminal  51  shown in  FIG. 3  and is structured as below. 
     The first terminal  251  is structured by a conductive terminal plate or so and includes a terminal body  251   a  and a protrusion plate part  251   b  formed by bending a sheet of conductive plate-like member of a metal plate or so. The terminal body  251   a  includes an outer-end-surface contact portion  251   a   1  with a substantially L shape attached to one terminal attachment surface  24   c   1  formed on the outer end surface  24   c  of the flange  24  shown in  FIG. 2  using adhesive or so. In addition, the terminal body  251   a  includes a mounting-side contact portion  251   a   2  with a rectangular plate shape formed by bending from the lower end of the outer-end-surface contact portion  251   a   1  in the Z-axis direction to the X-axis direction. 
     The outer-end-surface contact portion  251   a   1  of the terminal body  251   a  shown in  FIG. 6A  is fixed to the terminal attachment surface  24   c   1  of the flange  24  shown in  FIG. 2  using adhesive or so. The mounting-side contact portion  251   a   2  shown in  FIG. 6A  is contacted with the mounting-side core surface  24   a  shown in  FIG. 2  with a predetermined space (or no space). The outer surface of the mounting-side contact portion  251   a   2  located opposite to the surface contacted with the mounting-side core surface  24   a  shown in  FIG. 2  is a sub-mounting surface  251   a   3 . The role of the sub-mounting surface  251   a   3  is similar to that of the sub-mounting surface  51   a   3  shown in  FIG. 3 . 
     The protrusion plate part  251   b  shown in  FIG. 6A  and protruding outward in the Y-axis direction from the mounting-side core surface  24   a  of the flange  24  at the lower end of the flange  24  shown in  FIG. 2  is formed integrally with the mounting-side contact portion  251   a   2  of the terminal body  251   a  shown in  FIG. 6A . The protrusion plate part  251   b  includes a base part  251   c  being flush with the mounting-side contact portion  251   a   2  of the terminal body  251   a  and extending outward in the Y-axis direction and a tip bending part  251   d  bending downward in turn back manner in the Z-axis direction from the tip of the base part  251   c.    
     In the present embodiment, the tip bending part  251   d  bends downward in the Z-axis direction and turns back at the tip of the base part  251   c , the outer surface of the tip bending part  251   d  located opposite to the base part  251   c  is a main mounting surface  251   d   1 , and the inner surface of the tip bending part  251   d , where the base part  251   c  is located, is a connection surface (wire connection surface)  251   d   2 . A lead end  41   a  (one lead end) of a first wire  41  (one wire) constituting the coil unit  40  is sandwiched and caulked by the connection surface  251   d   2  of the tip bending part  251   d  and the base part  251   c . After the caulking, the terminal  251  and the lead end  41   a  of the wire  41  may be connected by soldering, laser welding, etc. 
     In the present embodiment, the main mounting surface  251   d   1  of the first terminal  251  protrudes downward in the Z-axis direction from the sub-mounting surface  251   a   3 , and the main mounting surface  251   d   1  is mainly connected to a circuit pattern of an external circuit board (not shown), but the sub-mounting surface  251   a   3  may also be connected to the circuit pattern at the same time. The connection to the circuit pattern of the external circuit board is carried out in any manner, such as solder connection. 
     In the present embodiment, the connection surface  251   d   2  (wire connection surface) and the main mounting surface  251   d   1  are formed on the front surface and the rear surface of the tip bending part  251   d  of the first terminal  251 , respectively. 
     Incidentally, the second terminal used for the coil device according to the present embodiment is symmetrical to the first terminal  251  in terms of shape and has the same structure excluding the symmetry. 
     A first terminal  251   a  shown in  FIG. 6B  is a modified example of the first terminal  251  according to the present embodiment. In the first terminal  251   a  according to the present embodiment, a step  253  is integrally formed between the mounting-side contact portion  251   a   2  and the base part  251   c , and the upper surface of the base part  251   c  is higher than that of the mounting-side contact portion  251   a   2  in the Z-axis direction. As a result, the main mounting surface  251   d   1  of the tip bending part  251   d  is substantially flush with the sub-mounting surface  251   a   3 . 
       FIG. 6C  illustrates another modified example of the first terminal  51  shown in  FIG. 3 . In this modified example, the tip bending part  51   d  shown in  FIG. 3  is not formed on the protrusion plate part  51   b , and the lead end  41   a  of the first wire is directly connected to the connecting surface  51   c   2  of the base part  51   c  by laser welding, soldering, heat welding, or the like. 
     Incidentally, the present invention is not limited to the above-mentioned embodiments and can variously be modified within the scope of the present invention. 
     In the above-mentioned embodiments, for example, the first flange  24  and the second flange  26  have the same structure, but may have different structures. The width of the notches  24   c   3  in the Y-axis direction formed at the lower ends of the flange  24  ( 26 ) of the drum core  20  shown in  FIG. 2  on both sides in the Y-axis direction may be large. For example, the notches  24   c   3  on both sides may be connected to each other in the Y-axis direction. In this case, the mounting-side core surface  24   a  ( 26   a ) of the flange  24  ( 26 ) of the drum core  20  shown in  FIG. 2  is flush with the bottom surface of the notches  24   c   3  ( 26   c   3 ). 
     In the above-mentioned embodiments, the plurality of wires (the first wire  41  and the second wire  42 ) is wound around the winding core  22  of the drum core  20 . In the present invention, however, a single wire (e.g., only the first wire  41 ) may be wound around the winding core  22  of the drum core  20 . In this case, the lead ends  41   a  and  41   b  on both ends of the first wire  41  are connected to any of the first terminal  51 ,  51   a ,  151 ,  151   a ,  251 , or  251   a  attached to the flanges  24  and  26 . The lead end  41   a  (one lead end) of the first wire  41  may be connected to the first terminal attached to the flange  24 , and the lead end  41   b  (the other lead end) may be connected to the second terminal attached to the flange  26 . 
     In the above-mentioned embodiments, the first terminal and the second terminal attached to each of the flanges  24  and  26  are insulated from each other, but when a single wire (e.g., only the first wire  41 ) is wound around the winding core  22  of the drum core  20 , the first terminal and the second terminal attached to the same flange  24  ( 26 ) may electrically be connected to each other. That is, the first terminal and the second terminal attached to the same flange  24  ( 26 ) may be formed integrally from a sheet of metal plate. 
     DESCRIPTION OF THE REFERENCE NUMERICAL 
     
         
         
           
               10 ,  110 ,  110   a  . . . coil device 
               20  . . . drum core 
               22  . . . winding core 
               24  . . . first flange 
               24   a  . . . mounting-side core surface 
               24   b  . . . anti-mounting-side core surface 
               24   c  . . . outer end surface 
               24   c   1  . . . terminal attachment surface 
               24   c   2  . . . terminal insulation projection 
               24   c   3  . . . notch 
               24   d  . . . inner surface 
               24   e  . . . lateral surface 
               26  . . . second flange 
               26   a  . . . mounting-side core surface 
               26   b  . . . anti-mounting-side core surface 
               26   c  . . . outer end surface 
               26   c   1  . . . terminal attachment surface 
               26   c   3  . . . notch 
               26   d  . . . inner surface 
               26   e  . . . lateral surface 
               30  . . . flat plate-like member 
               40  . . . coil unit 
               41  . . . first wire 
               41   a  . . . one lead portion (lead end) 
               41   b  . . . the other lead portion (lead end) 
               42  . . . second wire 
               42   a  . . . one lead portion (lead end) 
               42   b  . . . the other lead portion (lead end) 
               51 ,  51   a ,  151 ,  151   a ,  251 ,  251   a  . . . first terminal (terminal fitting) 
               51   a ,  151   a ,  251   a  . . . terminal body 
               51   a   1 ,  151   a   1 ,  251   a   1  . . . outer-end-surface contact portion 
               51   a   2 ,  151   a   2 ,  251   a   2  . . . mounting-side contact portion 
               51   a   3 ,  151   a   3 ,  251   a   3  . . . sub-mounting surface 
               151   a   4  . . . lateral contact portion 
               51   b ,  151   b ,  251   b  . . . protrusion plate part 
               51   c ,  251   c  . . . base part 
               51   c   1 ,  151   c   1 ,  251   d   1  . . . main mounting surface 
               51   c   2 ,  151   c   2 ,  251   d   2  . . . connection surface (wire connection surface) 
               151   c  . . . second base part 
               51   d ,  151   d ,  251   d  . . . tip bending part 
               151   e  . . . first base part 
               253  . . . step 
               52 ,  152 ,  152   a  . . . second terminal (terminal fitting) 
               52   a ,  152   a  . . . terminal body 
               52   a   1 ,  152   a   1  . . . outer-end-surface contact portion 
               52   a   2 ,  152   a   2  . . . mounting-side contact portion 
               52   a   3 ,  152   a   3  . . . sub-mounting surface 
               152   a   4  . . . lateral contact portion 
               52   b ,  152   b  . . . protrusion plate part 
               52   c  . . . base part 
               52   c   1 ,  152   c   1  . . . main mounting surface 
               52   c   2 ,  152   c   2  . . . connection surface (wire connection surface) 
               152   c  . . . second base part 
               52   d ,  152   d  . . . tip bending part 
               152   e  . . . first base part