Abstract:
The present invention is to provide a coil having flexibility even if it includes a core body. A flexible coil  10  comprises a plurality of sheet-like coils laminated together in a region sharing a magnetic flux, wherein each sheet-like coil has a coil section formed along a surface of an insulating sheet having flexibility; and magnetic bodies  80  and  81  that have flexibility and sandwich the plurality of the laminated sheet-like coils.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims priority to international application number PCT/JP 2006/319988 filed on Oct. 5, 2006 which claims priority to Japanese patent application bearing application number JP2005-353145 filed on Dec. 7, 2005, the entire disclosures of which are hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a flexible coil. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conventionally, a core body such as an inductor includes a ferrite sintered body or a body molded and pressed with metal powders. Further, an inductor having a hoop and the like used as an electrode is hardly deformed since rigidity of a core body is large. However, the inductor has weakness in bending, a shock of a dropping test and the like. Further, when the conventional inductor having large rigidity is mounted on a flexible substrate, it is possible to mount the inductor if the size of the inductor is small, but it is not possible to mount the inductor if the size is large since the inductor can&#39;t follow bending of a flexible substrate. As an inductor for overcoming such issue, an inductor disclosed in the patent document 1 is known for example. 
         [0004]    [Patent Document 1] 
         [0005]    Japanese Patent Application Laid-Open No. 2000-91135 (Refer to  FIG. 1  to  FIG. 3 ) 
       DISCLOSURE OF THE INVENTION 
       [0006]    The inductor disclosed in the patent document 1 comprises an inductor portion composed of a winding conductor integrally made of a thin copper plate and an insulating resin sheet having flexibility that is attached to both sides of the inductor portion. The inductor disclosed in the patent document 1 has flexibility since the inductor portion and the resin sheet have flexibility. 
         [0007]    The inductor disclosed in the patent document 1 has above-referenced structure, but does not include a magnetic material. Hence, the inductor is an air core coil type one which an inductance is small. In order to gain high inductance, it needs that a core body which has large rigidity and is made of a ferrite sintered body or a body pressed and molded with metal powders is provided within a coil. Accordingly, there is a disadvantage in that rigidity of an inductor becomes large as the above result. 
         [0008]    In order to overcome the above disadvantage, the present invention provides a coil having flexibility even if it comprises a core body. 
       MEANS TO SOLVE THE PROBLEM 
       [0009]    According to an aspect of the invention, a flexible coil comprising: a plurality of sheet-like coils laminated together in a region sharing a magnetic flux, wherein each sheet-like coil has a coil section formed along a surface of an insulating sheet having flexibility; and a plurality of magnetic bodies that have flexibility and sandwich the plurality of the laminated sheet-like coils. The above structure can attain flexibility for a coil. 
         [0010]    In addition to the aspect of the invention, the sheet-like coil may comprise a coil connecting portion installed in the inner periphery of the coil section and an electrode terminal portion installed in the outer periphery of the coil section, wherein the electrode terminal portion includes a terminal connecting portion that connects to the electrode terminal portion of the other sheet-like coil installed on a back side and wherein an end portion of the inner periphery of the coil section is connected to the coil connecting portion and an end of the outer periphery of the coil section is connected to the electrode terminal portion. In the above structure, the end portion in an inner periphery of the coil section can connect two coil sections so as to be one coil section, connecting the end portion in an outer periphery of each of coil sections to the electrode terminal portion. 
         [0011]    Further, in addition to the aspect of the invention, the coil connecting portion and the terminal connecting portion may be through hole portions which form a conductive layer in each of the inner surface. This structure can realize the coil connecting portion and the terminal connecting portion without changing the size and the thickness of the flexible coil. 
         [0012]    Further, in addition to the aspect of the invention, the flexible coil may have a structure where the other insulating sheet covers over a surface on which the coil section is exposed when the sheet-like coil is installed or a plurality of the sheet-like coils are laminated. 
         [0013]    Further, in addition to the aspect of the invention, the width of the other insulating sheet may be smaller than the width of the sheet-like coil and the electrode terminal portion may be exposed from both outsides of the other insulating sheet. 
         [0014]    Further, in addition to the aspect of the invention, one sheet-like coil including the coil section of which a diameter becomes smaller from a clockwise direction or a counter clock wise direction may be laminated with the other sheet-like coil including the coil section of which a diameter becomes lager from a clockwise direction or a counter clock wise direction. 
         [0015]    Further, in addition to the aspect of the invention, one or more holes and one or more concave portions may be formed in a center and both ends of the sheet-like coil and the magnetic body may have a configuration which gets into the holes and the concave portions. 
       EFFECT OF THE INVENTION 
       [0016]    The present invention can provide a coil having flexibility even if it comprises a core body. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]      FIG. 1  is a perspective view showing an overall appearance of first embodiment of a flexible coil. 
           [0018]      FIG. 2  is a perspective view showing a broken-down appearance of first embodiment of a flexible coil. 
           [0019]      FIG. 3  is a plain view of a coil unit which is a part of first embodiment of a flexible coil. 
           [0020]      FIG. 4  is a broken-down view of a coil unit which is a part first embodiment of a flexible coil. 
           [0021]      FIG. 5  is a cross section along A-A′ line in  FIG. 1  of first embodiment of a flexible coil. 
           [0022]      FIG. 6  is a graph showing a relationship between coupling coefficient and an inductance property of first embodiment of a flexible coil. 
           [0023]      FIG. 7  is a diagram showing processes of manufacturing second embodiment of a flexible coil. 
           [0024]      FIG. 8  is a diagram showing processes of manufacturing second embodiment of a flexible coil. 
           [0025]      FIG. 9  is a plain view of a first modification of the coil unit included in the first embodiment of a flexible coil. 
           [0026]      FIG. 10  is a broken-down view of the first modification of the coil unit included in the first embodiment of a flexible coil. 
           [0027]      FIG. 11  is a plain view of a second modification of the coil unit included in the first embodiment of a flexible coil. 
           [0028]      FIG. 12  is a broken-down view of a second modification of the coil unit included in the first embodiment of a flexible coil. 
       
    
    
       [0000]    
       
           10 : flexible coil, 
           20 ,  30 ,  40 ,  50 ,  31 ′,  41 ′,  51 ′: sheet-like coil 
           21 ,  31 ,  41 ,  51 : sheet body (insulating sheet having flexibility) 
           22 S,  32 S,  42 S,  52 S: coil connecting portion 
           22 Sh,  32 Sh,  42 Sh,  52 Sh: through hole portion 
           23 A,  23 B,  23 C,  23 D: electrode terminal portion 
           23   h ,  33   h ,  43   h ,  53   h : through hole portion (terminal connecting portion) 
           33 A,  33 B,  33 C,  33 D: electrode terminal portion 
           43 A,  43 B,  43 C,  43 D: electrode terminal portion 
           53 A,  53 B,  53 C,  53 D: electrode terminal portion 
           80 ,  81 : magnetic body 
           91 B,  92 B,  93 B,  94 B,  95 B,  96 B: electrode terminal portion 
           91 C,  92 C,  93 C,  94 C,  95 C,  96 C: sheet body (insulating sheet having flexibility) 
           91   h ,  92   h ,  93   h ,  94   h ,  95   h ,  96   h : through hole portion (terminal connecting portion) 
           91 S,  92 S,  93 S,  94 S,  95 S,  96 S: coil connecting portion 
           91 Sh,  92 Sh,  93 Sh,  94 Sh,  95 Sh,  96 Sh: through hole portion 
           101 B,  102 B,  103 B,  104 B: electrode terminal portion 
           101 C,  102 C,  103 C,  104 C sheet body (insulating sheet having flexibility) 
           101   h ,  102   h ,  103   h ,  104   h  through hole portion (terminal connecting portion) 
           101 S,  102 S,  103 S,  104 S coil connecting portion 
           101 Sh,  102 Sh,  103 Sh,  104 Sh through hole portion 
       
     
       DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment 
       [0050]    A flexible coil  10  of a first embodiment of the invention will be explained with referring to  FIG. 1  to  FIG. 6 . 
         [0051]      FIG. 1  is a perspective view of an overall appearance of the flexible coil  10 .  FIG. 2  is a broken-out perspective view of an overall appearance of the flexible coil  10 .  FIG. 3  is a plain view of a coil unit  70 .  FIG. 4  is a broken-out view of the coil unit  70 .  FIG. 5  is a cross section along A-A′ line in  FIG. 1  of the flexible coil  10 . 
         [0052]    The coil unit  70  comprises four sheet-like coils  20 ,  30 ,  40 ,  50  shown in  FIGS. 4  (A) to  4  (D) and an insulating sheet for covering  60  shown in  FIG. 4  (E). 
         [0053]    The structure of the sheet-like coil  20  and a method of manufacturing it will be explained with referring to  FIG. 4  (A). The sheet-like coil  20  comprises a sheet body  21 , a coil  22 , a coil connecting portion  22 S, four electrode terminal portions  23 A,  23 B,  23 C,  23 D and a through hole portion  23   h . The coil  22  is a coil section formed on a surface of the sheet body  21 . In the following explanation, the direction of connecting short sides of the sheet body  21  is defined as left and right directions (left and right sides) and the direction of connecting long sides is defined as upper and lower directions (upper and lower sides). Further, the surface on which a coil is formed in the sheet body  21  is a front surface (an upper surface) and the opposite surface of it is a back surface (a lower surface). 
         [0054]    The sheet body  21  is composed of a film body having insulation and flexibility such as polyimide or the like and its plain shape is rectangular. The coil  22  has a rectangular winded shape of which winded direction is changed to 90 degrees along a plain shape on one side surface of the sheet body  21 . A diameter of winding becomes smaller along a clockwise direction (the width of left and right directions or upper and lower directions in an inner periphery of the winded coil  22 .) The coil connecting portion  22 S is placed on the upper side of the sheet body  21 , which is the center of the left and right side, and in an inner periphery of the winding of the coil  22 . 
         [0055]    The electrode terminal portion  23 A is placed at the upper and left side on the surface of the sheet body  21  among electrode terminal portions  23 A,  23 B,  23 C and  23 D. The electrode terminal portion  23 B is placed at the upper and right side on the surface of the sheet body  21 . The electrode terminal portion  23 C is placed at the lower and left side on the surface of the sheet body  21 . The electrode terminal portion  23 D is placed at the lower and right side on the surface of the sheet body  21 . The shape of these electrode terminal portions  23 A,  23 B,  23 C and  23 D is a rectangular of which a longer side is along the direction of an edge of a short side portion. The two through hole portions  23   h  are placed on upper and lower directions in each of these electrode terminal portions  23 A,  23 B,  23 C and  23 D in order to form a terminal connecting portion. 
         [0056]    A rectangular space region  22 A where the coil  22  is not winded is formed within an inner periphery of the coil  22 . The coil  22  is winded three times. An end portion placed at the outside periphery of the winding is connected to the electrode terminal portion  23 A on an upper and left area. The other end portion placed at an inner periphery of the winding is connected to the coil connecting portion  22 S. 
         [0057]    The sheet-like coil  20  having the above structure is manufactured by the following processes. 
         [0058]    First, a thin electrolytic copper foil is attached to an entire surface on one side of the sheet body  21  with an adhesive so that a thin copper foil layer is formed on the sheet body  21 . A heat proof epoxy resin or a polyimide resin is used as an adhesive, in considering resistance to heat. Instead of a thin electrolytic copper foil, a rolled copper foil may be attached to form a copper foil layer. 
         [0059]    The through hole portion  22 Sh is formed in the coil connecting portion  22 S of the sheet body  21  in which the copper foil layer is formed by drilling or laser irradiation. The through hole portions  23   h  are also formed by a similar way. 
         [0060]    Then, a conductive material such as copper is deposited by electrolytic plating in an inner periphery of the through hole portion  22 Sh in order to be electrically connected to the copper foil layer. Depositing a conductive material such as copper with plating in an inner periphery of the through hole portion  22 Sh electrically connects the plated copper area with the copper foil layer to form the coil connecting portion  22 S. Before plating copper, it is preferable that a conductive primer be coated in order that copper is easily plated. 
         [0061]    A conductive material such as copper is also deposited by plating in an inner periphery of through hole portions  23   h  in order to be electrically connected to the copper foil layer. Depositing a conductive material such as copper with plating in an inner periphery of the through hole portions  23   h  electrically connects the plated copper area with the copper foil layer to form the through hole portions  23   h  as the terminal connecting portion. Before plating copper, it is preferable that a conductive primer be coated in order that copper is easily plated similarly to the plating to the through hole portion  22 Sh. 
         [0062]    Then, a resist layer is formed along the shapes of the coil  22 , and electrode terminal portions  23 A,  23 B,  23 C, and  23 D. In other words, the resist layer is formed so that one end part of the coil  22  is connected to the plated copper area formed in the through hole portion  22 Sh such as the coil connecting portion  22 S and the other end part is connected to the electrode terminal portion  23 A. Then, the coil  22 , electrode terminal portions  23 A,  23 B,  23 C, and  23 D are formed by etching the resist layer. 
         [0063]    Accordingly, the sheet body  21  has flexibility and the coil  22  has a thickness of the electrolytic copper foil or the rolled copper foil so that the sheet-like coil  20  becomes totally flexible. 
         [0064]    Next, the structure of the sheet-like coil  30  shown in  FIG. 4(B)  and a method of manufacturing it will be explained. 
         [0065]    The sheet-like coil  30  comprises a sheet body  31  having the same size as the sheet body  21 , a coil  32  formed on the sheet surface of the sheet body  31 , a coil connecting portion  32 S, four electrode terminal portions  33 A,  33 B,  33 C and  33 D and through hole portions  33   h.    
         [0066]    The sheet-like coil  30  has the same structure as the sheet-like coil  20  and a method of manufacturing it is the same for the sheet-like coil  20  except that the configuration of the coil  32  is different from that of the coil  22  of the sheet-like coil  20  as the following. In other words, the coil  22  of the sheet-like coil  20  has a configuration in which the winding diameter becomes smaller along a clockwise direction. On the other hand, the coil  32  has a configuration in which the winding diameter becomes larger along a clockwise direction 
         [0067]    Further, in the sheet-like coil  20 , the end portion at the outside periphery of winding of the coil  22  is connected to the electrode terminal portion  23 A located at the upper and left position. On the other hand, in the sheet-like coil  30 , the end portion at the outside periphery of winding of the coil  32  is connected to the electrode terminal portion  33 B located at the upper and right position. The coil connecting portion  32 S is located in the inner periphery of the coil  32  and the upper side of the sheet  31 , which is a center along left and right directions. In other words, the position of the coil connecting portion  22 S on the surface of the sheet body  21  (the position along the outside periphery of the sheet body  21 ) is the same position as the coil connecting portion  32 S on the surface of the sheet body  31  (the position along the outside periphery of the sheet  31 ). Further, the coil connecting portion  32 S (a through hole portion  32 Sh) is connected to the end portion of an inner periphery of the winding of the coil  32 . 
         [0068]    The sheet-like coil  30  has the same structure as the sheet-like coil  20  except the above description. In other words, forming of the coil  32 , electrode terminal portions  33 A,  33 B,  33 C,  33 D and through hole portions  32 Sh and  33   h , and plating copper within these through hole portions are the same forming as the above description for the sheet-like coil  20 . The diameter and the configuration of inner periphery of the winding in the coil  22  are the same of that in the coil  32 . The position of the space region  32 A on the surface of the sheet body  31  (the position along the outside periphery of the sheet  31 ) is the same position as the space region  22 A on the surface of the sheet body  21  (the position along the outside periphery of the sheet body  21 ). 
         [0069]    Accordingly, the sheet body  31  has flexibility and the coil  32  has a thickness of the electrolytic copper foil or the rolled copper foil so that the sheet-like coil  30  also becomes totally flexible. 
         [0070]    Next, the structure of the sheet-like coil  40  shown in  FIG. 4(C)  and a method of manufacturing it will be explained. 
         [0071]    The sheet-like coil  40  comprises a sheet body  41  of which size is the same of the sheet body  21 , a coil  42  which is formed on the sheet surface of the sheet body  41 , a coil connecting portion  42 S, four electrode terminal portions  43 A,  43 B,  43 C,  43 D and through hole portions  43   h . The sheet-like coil  40  also has the same structure as the sheet-like coil  20  and formed by the same method of manufacturing the sheet-like coil  20  similarly to the sheet-like coil  30  except the following point being different from the coil  22  of the sheet-like coil  20 . In other words, the coil  22  of the sheet-like coil  20  has a configuration in which a winding diameter becomes smaller along a clockwise direction. On the other hand, the coil  42  has a configuration in which a winding diameter becomes larger along a clockwise direction. 
         [0072]    Further, in the sheet-like coil  20 , the end portion located at the outer periphery of the winding of the coil  22  is connected to the electrode terminal portion  23 A located at the left and upper area. In the sheet-like coil  40 , the end portion located at the outer periphery of the winding of the coil  42  is connected to the electrode terminal portion  43 C located at the left and lower area. Further, in the sheet-like coil  20 , the coil connecting portion  22 S is placed on the upper area of the sheet body  21 , which is a center along left and right directions. In the sheet-like coil  40 , the coil connecting portion  42 S is located in the inner periphery of the coil  42  and placed on the lower area of the sheet body  41 , which is a center along left and right directions. The coil connecting portion  42 S (the through hole portion  42 Sh) is connected to the end portion of the inner periphery of the winding of the coil  42 . 
         [0073]    The sheet-like coil  40  has the same structure as the sheet-like coil  20  except the above description. In other words, the coil  42 , electrode terminal portions  43 A,  43 B,  43 C,  43 D and through hole portions  42 Sh and  43   h  are formed and the inside of these through hole portions are plated with copper by the same method as forming the sheet-like coil  20 . 
         [0074]    The diameter and the configuration of the winding in the inner periphery of the coil  42  are the same ones as the diameter and the configuration of the winding in the inner periphery of the coil  22 . The position (the position of the outer periphery of the sheet body  41 ) in which the space region  42 A is formed on the sheet  41  is the same position as position (the position of the outer periphery of the sheet body  21 ) in which the space region  22 A is formed on the sheet body  21 . In the sheet-like coil  40 , the sheet body  41  has flexibility similarly to the sheet-like coil  20 , and the coil  42  is formed with an electrolytic copper thin film and has a thickness of a rolled copper thin film, making the sheet-like coil  30  totally hold flexibility. 
         [0075]    In the embodiment, the sheet-like coil  40  is a thing which is obtained by rotating the sheet-like coil  30  by 180 degree. 
         [0076]    Next, the structure of the sheet-like coil  50  and a method of manufacturing it will be explained with referring to  FIG. 4  (D). 
         [0077]    The sheet-like coil  50  comprises a sheet body  51  of which size is the same as the sheet body  21 , a coil  52  which is formed on the sheet surface of the sheet body  51 , a coil connecting portion  52 S, four electrode terminal portions  53 A,  53 B,  53 C,  53 D and through hole portions  53   h.    
         [0078]    The sheet-like coil  50  has the same structure as the sheet-like coil  20  and formed by the same method as manufacturing the sheet-like coil  20  similarly to the sheet-like coil  40  except the following point being different from the coil  22  of the sheet-like coil  20 . In other words, in the sheet-like coil  20 , the end portion located at the outer periphery of the winding of the coil  22  is connected to the electrode terminal portion  23 A located at the left and upper area. In the sheet-like coil  50 , the end portion located at the outer periphery of the winding of the coil  52  is connected to the electrode terminal portion  53 D located at the right and lower area. 
         [0079]    Further, in the sheet-like coil  20 , the coil connecting portion  22 S is placed on the upper area of the sheet body  21 , which is a center along left and right directions. In the sheet-like coil  50 , the coil connecting portion  52 S is located in the inner periphery of the coil  52  and placed on the lower area of the sheet body  51 , which is a center along left and right directions. The coil connecting portion  52 S (the through hole portion  52 Sh) is connected to the end portion of the inner periphery of the winding of the coil  52 . 
         [0080]    Here, the position (the position of the outer periphery of the sheet body  51 ) at which the coil connecting portion  52 S is placed on the sheet body  51 , is the same position as position (the position of the outer periphery of the sheet body  41 ) at which the coil connecting portion  42 S is placed on the sheet body  41 . 
         [0081]    The sheet-like coil  50  has the same structure as the sheet-like coil  20  except the above description. In other words, the coil  52 , electrode terminal portions  53 A,  53 B,  53 C,  53 D and through hole portions  52 Sh,  53   h  are formed, and the inside of these through hole portions are plated with copper by the same method as forming the sheet-like coil  20 . 
         [0082]    The diameter and the configuration of the winding in the inner periphery of the coil  52  are the same ones as the diameter and the configuration of the winding in the inner periphery of the coil  22 . The position (the position of the outer periphery of the sheet body  51 ) in which the space region  52 A is formed on the sheet  51  is the same position as position (the position of the outer periphery of the sheet body  21 ) in which the space region  22 A is formed on the sheet body  21 . 
         [0083]    Similarly to the sheet-like coil  20 , in the sheet-like coil  50 , the sheet body  51  has flexibility and the coil  52  is formed with a thickness of an electrolytic copper thin film or a rolled copper thin film, making the sheet-like coil  50  totally hold flexibility. 
         [0084]    In the embodiment, the sheet-like coil  50  is a thing which is obtained by rotating the sheet-like coil  20  by 180 degree. 
         [0085]    An insulating sheet for a cover  60  shown in  FIG. 4(E)  has a width (L 60 ) along upper and lower directions which is the same width as the sheet body  20  ( 30 ,  40 , and  50 ). Further, the width (W 60 ) along left and right directions is almost equal to a space (w) along left and right directions as shown in  FIG. 4  (D) where electrode terminal portions  53 A,  53 B or  53 C,  53 D are installed. The insulating sheet for a cover  60  is composed of a polyimide film which is the same material as the sheet body  20  ( 30 ,  40  and  50 .) 
         [0086]    These sheet-like coils  20 ,  30 ,  40 ,  50  described above are laminated in this order in order that the each surface of coils in these sheet-like coils does not face the other surface of the other coil, in other words the front surface of one coil sheet faces the back surface of the other sheet-like coil. 
         [0087]    To explain further in details, the sheet-like coil  20  and the sheet-like coil  30  are laminated so as to make the side of the sheet body  31  (in which the coil  32  is not formed) of the sheet-like coil  30  face the surface of the sheet-like coil  20  in which the coil  22  is installed. Then, the sheet-like coil  40  is laminated over the sheet-like coil  30  so as to make the side of the sheet body  41  (in which the coil  42  is not formed) of the sheet-like coil  40  face the surface of the sheet-like coil  30  in which the coil  32  is installed. Further, the sheet-like coil  40  is laminated over the sheet-like coil  50  so as to make the side of the sheet body  51  (in which the coil  52  is not formed) of the sheet-like coil  50  face the surface of the sheet-like coil  40  in which the coil  42  is installed. Upper and lower or left and right directions of these laminated sheet-like coils  20 ,  30 ,  40  and  50  are adjusted so that the electrode terminal portions  23 A,  33 A,  43 A and  53 A are positioned on a left and upper area. 
         [0088]    When the sheet-like coil  30  is laminated on the sheet-like coil  20 , such laminating makes the coil connecting portion  22 S face the coil connecting portion  32 S along upper and lower directions. Accordingly, the coil connecting portion  22 S faces the coil connecting portion  32 S along upper and lower directions each other, making a copper plated surface within the through hole portion  32 Sh be connected to a copper plated surface within the thorough hole portion  22 Sh. Further, the coil  22  is connected to the coil  32  with the coil connecting portions  22 S and  32 S, forming a singularly linked coil. Electrode terminal portions  23 A and  33 B become electrode terminal portions of a coil where coils  22  and  32  are singularly linked together. 
         [0089]    In general, when a coil is formed on the surface of the sheet body and an electrode terminal portion for input and output is installed at the periphery of the coil, a part of inner winded conductive wire which is drawn out from an inner periphery to an outer periphery is crossed with a winded conductive wire. However, in above described case, a part of conductive wires crossing each other has to be insulated, making a structure being complex. 
         [0090]    On the other hand, in the above described sheet-like coils  20  and  30 , these sheet-like coils are laminated so as to connect the coil connecting portion  22 S to the coil connecting portion  32 S only. This arrangement insulates a space between the coil  22  and the coil  32  using the sheet body  31  except a connection of the coil connecting portion  22 S to the coil connecting portion  32 S and places electrode terminal portions  23 A and  33 B at the outer periphery of these coils as electrode terminal portions for input and output. 
         [0091]    When the sheet-like coil  50  is laminated on the sheet-like coil  40 , such lamination makes the coil connecting portion  42 S face the coil connecting portion  52 S along upper and lower directions. Accordingly, the coil connecting portion  42 S faces the coil connecting portion  52 S along upper and lower directions each other, making a copper plated surface within the thorough hole portion  52 Sh be connected to a copper plated surface within the thorough hole portion  42 Sh. Further, the coil  42  is connected to the coil  52  with the coil connecting portions  42 S and  52 S, forming a singularly linked coil. Electrode terminal portions  43 C and  53 C become electrode terminal portions of a coil where coils  42  and  52  are singularly linked together. 
         [0092]    In the above described sheet-like coils  40  and  50 , these sheet-like coils are laminated so as to connect the coil connecting portion  42 S to the coil connecting portion  52 S only similarly to the sheet-like coils  20  and  30 . This arrangement insulates a space between the coil  42  and the coil  52  using the sheet body  51  except a connection of the coil connecting portion  42 S to the coil connecting portion  52 S and places electrode terminal portions  43 C and  53 D at the outer periphery of these coils as electrode terminal portions for input and output. 
         [0093]    Further, sheet-like coils  20 ,  30 ,  40  and  50  are laminated so that four electrode terminal portions installed at upper and lower area, and left and right sides of each sheet-like coil are overlapped over other electrode terminal portions of other sheet-like coil as the same positional relationship. 
         [0094]    In other words, such laminated structure overlaps electrode terminal portions  23 A,  33 A,  43 A and  53 A each other along upper and lower directions. Further electrode terminal portions  23 B,  33 B,  43 B and  53 B are overlapped each other along upper and lower directions. Further, electrode terminal portions  23 C,  33 C,  43 C and  53 C are overlapped each other along upper and lower directions. Further electrode terminal portions  23 D,  33 D,  43 D and  53 D are overlapped each other along upper and lower directions. 
         [0095]    The above structure makes a copper plated portion formed within an inner surface of the through hole portion connect the electrode terminal portion placed in the backside, connecting electrode terminal portions each other with the through hole portion. Such thought hole portion is formed in the electrode terminal portion placed on the front surface. 
         [0096]    In other words, the inner surfaces of the through hole portions  33   h ,  43   h ,  53   h  of electrode terminal portions  33 A,  43 A,  53 A are plated with copper. Hence, the electrode terminal portion  53 A is connected to the electrode terminal portion  43 A located at the back side of the electrode terminal portion  53 A with the through hole portions  53   h . Further, the electrode terminal portion  43 A is connected to the electrode terminal portion  33 A located at the back side of the electrode terminal portion  43 A with the through hole portions  43   h . Further, the electrode terminal portion  33 A is connected to the electrode terminal portion  23 A located at the back side of the electrode terminal portion  33 A via the through hole portions  33   h.    
         [0097]    Other electrode terminal portions  23 B,  33 B,  43 B and  53 B are also connected to other electrode terminal portions  23 C,  33 C,  43 C and  53 C and other electrode terminal portions  23 D,  33 D,  43 D and  53 D via the through hole portions  33   h ,  43   h  and  53   h.    
         [0098]    As described above, the insulating sheet for a cover  60  is laminated over the sheet-like coil  50  which is one of after sheet-like coils  20 ,  30 ,  40  and  50  are laminated without covering over electrode terminal portions  53 A,  53 B,  53 C and  53 D so that the coil unit  70  is formed as shown in  FIG. 3 . 
         [0099]    As shown in  FIG. 4  (E), the width (W 60 ) of the insulating sheet for a cover  60  has the same width (W) as left and right directions of the electrode terminal portions  53 C and  53 D, covering only the coil  52  without covering electrode terminal portions  53 A,  53 B,  53 C and  53 D. 
         [0100]    Here, when the sheet-like coils  20 ,  30 ,  40  and  50  are laminated as described above, their outer edges are mostly aligned together since the sizes and configurations of the sheet bodies  21 ,  31 ,  41  and  51  are the same together. 
         [0101]    Space regions  22 A,  32 A,  42 A and  52 A placed at the same position and on the surfaces of sheet bodies  21 ,  31 ,  41 , and  51  are overlapped each other along upper and lower directions (laminated directions) of sheet-like coils  20 ,  30 ,  40  and  50 . In other words, each of coils  22 ,  32 ,  42  and  52  shares its magnetic circuit with each of space regions  22 A,  32 A,  42 A and  52 A. 
         [0102]    Here, the coil  32  is insulated from the coil  42  because of existence of the sheet body  41  between the coils  32  and  42 . 
         [0103]    As described above, the sheet-like coils  20 ,  30 ,  40  and  50  and the insulating sheet for a cover  60  are laminated. Then, the insides of space regions  22 A,  32 A,  42 A and  52 A are punched out like a rectangle to form a hole portion  70 A (see  FIG. 3 .) 
         [0104]    Further, upper and lower side edge portions of the sheet-like coils  20 ,  30 ,  40  and  50  and the insulating sheet for a cover  60  are punched out so as to make upper and lower side edge portions be a rectangular U-shape toward inner sides from these lower side edge portions to form a concave portion  70 B. 
         [0105]    In other words, the coil unit  70  includes the hole portion  70 A inside and the concave portion  70 B is formed at the upper and lower side edges. 
         [0106]    The coil unit  70  formed by the method described above has flexibility since sheet-like coils  20 ,  30 ,  40  and  50  and the insulating sheet  60  have flexibility. 
         [0107]    Next, the coil unit formed by the above method is thermally pressed while being sandwiched with magnetic bodies  80  and  81  from both sides along upper and lower directions as shown in  FIG. 2 . 
         [0108]    The magnet body  80  formed on the front surface of the sheet-like coil  50  has the width (L 80 ) along upper and lower directions and the width (W 80 ) along left and right directions which are almost equal to that of the insulating sheet for a cover  60  and does not cover over electrode terminal portions  53 A,  53 B,  53 C and  53 D. 
         [0109]    The magnet body  81  formed on the back surface of the sheet-like coil  20  is formed on the surface which is the almost same size as the sheet-like coil  20  and covers over the entire back surface of the sheet body  21  of the sheet-like coil  20 . 
         [0110]    Magnetic bodies  80  and  81  are composed of a flexible and magnetic thin plate body or a sheet body in which are formed by mixing an elastomer resin with iron powders as magnetic powders. Hence, when these magnetic bodies  80  and  81  are thermally pressed with sandwiching the coil unit  70 , magnetic bodies get into the hole portion  70 A and the concave portion  70 B. Further, magnetic bodies  80  and  81  are integrated into a single magnetic body, forming a core for coils  22 ,  32 ,  42 , and  52 . 
         [0111]    As a result, magnetic bodies  80  and  81  exist in the hole portion  70 A and the concave portion  70 B as shown in  FIG. 5  which is a cross section along the line A-A in  FIG. 1 . When a current flows in coils  22 ,  32 ,  42  and  52 , a closed magnetic circuit is formed around the coils  22 ,  32 ,  42  and  52 . 
         [0112]    The flexible coil  10  formed as described above, has flexibility since the coil unit  70  has flexibility and magnetic bodies  80 ,  81  has also flexibility. Accordingly, the flexible coil  10  includes magnetic bodies  80  and  81  as a core and flexibility. 
         [0113]    In the flexible coil  10 , electrode terminal portions  53 A,  53 B,  53 C and  53 D are exposed from the magnetic body  80  as shown in  FIG. 1 . Electrode terminal portions  53 A and  53 B work as electrode terminal portions for coils  22  and  32  singularly linked together and electrode terminal portions  53 C and  53 D work as electrode terminal portions for coils  42  and  52  singularly linked together. 
         [0114]    In other words, the electrode terminal portion  53 A is electrically connected to the electrical terminal portion  23 A which connects to an end part of the coil  22  via the through hole portions  43   h  in the electrode terminal portion  43 A and the through hole portions  33   h  in the electrode terminal portion  33 A. The through hole portions  43   h  and the through hole portions  33   h  singularly linked together oppose to two through hole portions  53   h  installed in the electrode terminal portion  53 A. 
         [0115]    Further, the electrode terminal portion  53 B is electrically connected to the electrical terminal  23 B which is connected to a part of the coil  32  via the through hole portions  43   h  in the electrode terminal portion  43 B and the through hole portions  33   h  in the electrode terminal portion  33 B. The through hole portions  43   h  and the through hole portions  33   h  singularly linked together oppose two through hole portions  53   h  installed in the electrode terminal portion  53 B. 
         [0116]    The coil  22  is electrically connected to the coil  32  together via the through hole portion  32 Sh. Hence, the electrode terminal portions  53 A and  53 B work as electrode terminal portion of the coils  22  and  32  which are singularly linked together. 
         [0117]    Further, the electrode terminal portion  53 C is electrically connected to the electrode terminal portion  43 C via two through hole portions  53   h  which are installed on the electrode terminal portion  53 C. The electrode terminal portion  43 C is electrically connected to an end part of the coil  42 . The electrode terminal portion  53 D directly becomes an electrode terminal portion of the coil  52 . 
         [0118]    The coil  52  is electrically connected to the coil  42  together via the through hole portion  52 Sh. Hence, the electrode terminal portions  53 C and  53 D work as electrode terminal portion of the coils  42  and  52  which are singularly linked together. 
         [0119]    The flexible coil  10  composed of the above structure is configured as a so-called two-circuits and four-terminals coil. 
         [0120]    In other words, the coil  22  and the coil  32  which are connected together via the coil connecting portion  32 S constitute a first coil (or a secondary coil) and the coil  52  and the coil  42  which are connected together via the coil connecting portion  52 S constitute a secondary coil (or a first coil.) Then, the electrode terminal portions  53 A and  53 B work as input and output terminals of the coil  22  and the coil  32 . The electrode terminal portions  53 C and  53 D work as input and output terminals of the coil  42  and the coil  52 . 
         [0121]    In the embodiment described above, the sheet bodies  21 ,  31 ,  41  and  51  are made of polyimide film. But, they may be made of a resin such as a polyethylene terephthalate resin and a polyethylene naphthalene resin. 
         [0122]    Further, the magnetic body was manufactured by mixing an elastomer resin with iron powders as magnetic powders. But, it may be manufactured by using and mixing silicone rubber having rubber cross linker or an epoxy resin with iron powders, sendust powders, or soft metal powders such as permalloy powders or the like. 
         [0123]    Further, in the embodiment, the numbers of winding in the first side is the same numbers as winding in the secondary side. But, the numbers of winding in the first side may be made to be different from the numbers of winding in the secondary side. Such different winding boosts a voltage applied to either of coils desponding on the ratio of numbers of winding as a transformer. 
         [0124]    Here, electrode terminal portions  23 B,  23 C,  23 D,  33 C,  33 D and  43 D are unnecessary since lower sides of them are not electrode terminal portions connected to the coils  22  and  32 . 
         [0125]    In other words, for example, it is not necessary that the electrode terminal portion  53 A is connected to the electrode terminal portion  23 A connected to the coil  22  via through hole portions  43   h  and  33   h  such as electrode terminal portions  33 A and  43 A. 
         [0126]    Hence, it is not necessary that these electrodes are formed in view of function for the flexible coil  10 , but these electrodes do not work their function even when they are formed. Hence, a mask pattern for forming electrode terminal portions is shared for all sheet-like coils  20 ,  30 ,  40  and  50  so as to reduce a manufacturing cost. In other words, a mask pattern for forming a resist layer portion is shared for all sheet-like coils  20 ,  30 ,  40  and  50 . The resist layer portion has a configuration which corresponds to the configuration of the electrode terminal portion including the copper thin film formed on the sheet body. 
         [0127]    The flexible coil  10  in the embodiment can attain a high coupling coefficient as shown in a graph of  FIG. 6 . This high coupling coefficient can be attained since the sheet body  41  made of non magnetic polyimide is sandwiched between a first coil and secondary coil. In  FIG. 6 , “coil  1 ” is indicated as a coil comprising the coil  22  and the coil  32  and “coil  2 ” is indicated as a coil comprising the coil  42  and the coil  52 . 
       Second Embodiment 
       [0128]    Next, the flexible coil  10  regarding a second embodiment will be explained referring to  FIG. 7  and  FIG. 8 . In the second embodiment, only a coil unit  70 ′ in the flexible coil  10  is different from a coil unit  70  in the flexible coil  10  in the first embodiment. The structure of it and a method of manufacturing it will be mainly explained. 
         [0129]    The method of manufacturing the coil unit  70 ′ is different from the method of manufacturing the coil unit  70 , the coil unit  70 ′ has a structure different from the coil unit  70  due to such different manufacturing method. But, basic structure of the coil unit  70 ′ is the same as the coil unit  70 . Hence, the same numeral references in the coil unit  70  shown in  FIG. 4  are applied to components in the coil unit  70 ′ and their explanation will be omitted. The coil unit  70 ′ is a two-circuits and four-terminals coil such as the coil unit  70 . 
         [0130]    First, the sheet body  41  is prepared as shown in  FIG. 7  (A) Then, an electrolytic copper foil is attached to entire front and back surfaces of the sheet body  41  to form a copper foil layers  32 A and  42 A ( FIG. 7  (B)). Then, the resist layer  32 B is coated on the back surface of the copper foil layer  32 A and the resist layer  42 B is also coated on the front surface of the copper foil layer  42 A. Then, as shown in  FIG. 7  (D), the resist layer  32 B is etched to form a resist pattern  32 B′ of which shape corresponds to pattern configurations of the coil  32  and electrode terminal portions  33 A,  33 B,  33 C and  33 D ( FIG. 4  (B)). Further, the resist layer  42 B is etched to form a resist layer pattern  42 B′ of which shape corresponds to pattern configurations of the coil  42  and electrode terminal portions  43 A,  43 B,  43 C and  43 D ( FIG. 4  (C)). 
         [0131]    Then, copper foils are etched ( FIG. 7  (E)) and resist layers are removed ( FIG. 7  (F)) to form the coil  42  and electrode terminal portions  43 A,  43 B,  43 C and  43 D. The coil  42  and electrode terminal portions  33 A,  33 B,  33 C and  33 D are formed on the back surface of the sheet body  41 . In other words, the sheet-like coil  41 ′ comprising the coil  32  and the coil  42  on the sheet body  41  is formed. 
         [0132]    Then, as shown in  FIG. 7  (G), the sheet body  51  is laminated on the front surface of the sheet-like coil  41 ′ while sandwiching the coil  42  and electrode terminal portions  43 A,  43 B,  43 C, and  43 D and being attached to their surfaces with an adhesive. Further, the sheet body  31  is formed on the back surface of the sheet-like coil  41 ′ while covering over the coil  32  and electrode terminal portions  33 A,  33 B,  33 C and  33 D and being attached to their surfaces with an adhesive. Further, an electrolytic copper foil is attached to the front surface of the sheet body  51  with an adhesive to form a copper foil layer  52 A. An electrolytic copper foil is attached to the back surface of the sheet body  31  with an adhesive to form a copper foil layer  22 A. 
         [0133]    Then, as shown in  FIG. 7  (H), a through hole portion H 1  is formed at the position corresponding to the through hole portions  22 Sh and  32   h  shown in  FIGS. 4  (A) and  4  (B). Further, a through hole portion H 2  is formed at the position corresponding to the through hole portions  42 Sh and  52 Sh shown in  FIGS. 4  (C) and  4  (D). Other through hole portions not shown in any figures are formed at the position corresponding to the through hole portions  23   h ,  33   h ,  43 Sh and  53   h  formed on electrode terminal portions shown in  FIGS. 4  (A) to  4  (E). 
         [0134]    Then, as shown in  FIG. 7  (I), a layer M 1  is plated while covering over the inner surfaces of the through hole portions H 1  and H 2 , the inner surfaces of the through hole portion not shown in the figure corresponding to the through hole portions  23   h ,  33   h ,  43   h  and  53   h  and entire surfaces of copper foil layers  22 A and  52 A. 
         [0135]    Then, a resist layer R is coated covering over the plated layer M 1  and the inner surface of through hole portions H 1  and H 2  ( FIG. 8  (J)). Then, as shown in  FIG. 8  (K), the resist layer R on the front surface of the copper foil layer  52 A is etched to form a resist layer pattern  52 R of which shape corresponds to pattern configurations of the coil  52  and electrode terminal portions  53 A,  53 B,  53 C and  53 D (see  FIG. 4  (D)). Further, the resist layer R on the back surface of the copper foil layer  22 A is etched to form a resist pattern  22 R of which shape corresponds to pattern configurations of the coil  22  and electrode terminal portions  23 A,  23 B,  23 C and  23 D ( FIG. 4  (A)). Then, copper foils are etched ( FIG. 8  (L)) and resist layers are removed ( FIG. 8  (M)) to form the coil  52  and electrode terminal portions  53 A,  53 B,  53 C and  53 D on the front surface of the sheet body  51 . Further, the coil  22  and electrode terminal portions  23 A,  23 B,  23 C and  23 D are formed on the back surface of the sheet body  31 . 
         [0136]    In other words, the sheet-like coil  51 ′ comprising the coil  52  on the sheet body  51  is laminated on the surface of the coil  42  of the sheet-like coil  41 ′. Further, the sheet-like coil  31 ′ comprising the coil  22  on the sheet body  31  is laminated on the surface of the coil  32  of the sheet-like coil  41 ′. 
         [0137]    Then, as shown in  FIG. 8  (N), the insulating sheet for a cover  60  is laminated on the front surface of the sheet-like coil  51 ′ while covering over the coil  52  and being attached to the coil  52  with an adhesive. Further, the sheet body  21  is laminated on the back surface of the sheet-like coil  31 ′ while covering over the coil  22  and electrode terminal portions  23 A,  23 B,  23 C and  23 D and being attached to their surfaces with an adhesive. 
         [0138]    A hole portion  70 A is formed by punching through the insides of spaces  22 A,  32 A,  42 A and  52 A of the coils  22 ,  32 ,  42  and  52  with a rectangular shape while the sheet-like coils  41 ′,  51 ′ and  31 ′, the sheet body  60  and the sheet body  21  are laminated each other. Further the concave portion  70 B is punched so as to depress upper and lower edge side portions of the sheet-like coil  41 ′, the sheet-like coil  51 ′ the sheet-like coil  31 ′, the insulating sheet for a cover  60  and the sheet body  21  toward inside from these upper and lower edge side portion. 
         [0139]    The coil unit  70 ′ formed by the above method comprises the coil  22  and the coil  32  which are connected each other via the plated layer M 1  formed in the inside of the through hole portion H 1 . The coil  22  and the coil  32  are singularly linked. Electrode terminal portions  23 A and  33 B become electrode terminal portions of singularly linked coils  22  and  32 . Further, the coil  42  is connected to the coil  52  via the plated layer M 1  formed in the inner surface of the through hole portion H 2  and the coil  42  and the coil  52  are singularly linked together. Electrode terminal portions  43 C and  53 D become electrode terminal portions of coils  42  and  52  singularly linked together. 
         [0140]    Electrode terminal portions  23 A,  33 A,  43 A and  53 A are connected each other via the plated layer M 1  formed in the inner surface of the through hole portion not shown in any figures. Electrode terminal portions  23 B,  33 B,  43 B and  53 B, electrode terminal portions  23 C,  33 C,  43 C and  53 C and electrode terminal portions  23 A,  33 A,  43 A and  53 A are connected each other via the plated layer M 1  formed in the inner surface of the through hole portion not shown in any figures. In other words, the electrode terminal portion  53 A is connected to the electrode terminal portion  23 A which is one of electrode terminal portions for the coil  22  and the coil  32  singularly linked together. The electrode terminal portion  53 B is connected to the electrode terminal portion  33 B which is the other terminal. Hence, electrode terminal portions  53 A and  53 B work as electrode terminal portions for the coils  22  and  32  singularly linked together. The electrode terminal portion  53 C is connected to the electrode terminal portion  43 C which is one of electrode terminal portions for the coil  42  and the coil  52  singularly linked together. Hence, electrode terminal portions  53 C and  53 D work as electrode terminal portions for the coils  42  and  52  singularly linked together. 
         [0141]    Magnet bodies  80  and  81  are laminated on the coil unit  70 ′ formed as described above so as to constitute the flexible coil  10 . 
       (First Modification) 
       [0142]    The coil unit  70  of the flexible coil  10  in the first embodiment is two-circuits and four terminals coil. On the other hand,  FIGS. 9 and 10  show a coil unit  90  comprising three-circuits and six-terminals coil. 
         [0143]    The coil unit  90  comprises six sheet-like coils  91 ,  92 ,  93 ,  94 ,  95  and  96  shown in  FIGS. 10  (A) to  10  (F) and an insulating sheet for a cover  97  shown in  FIG. 10  (G.) 
         [0144]    The coil unit  90  comprises sheet-like coils  91  and  92  singularly linked together and sheet-like coils  93  and  94  singularly linked together. Further, sheet-like coils  95  and  96  are singularly linked together. 
         [0145]    Sheet-like coils  91 ,  92 ,  93 ,  94 ,  95  and  96  have the same structure as the sheet-like coil  20  and the like. Hence, explanation of details are omitted and only the different parts between sheet-like coils  91 ,  92 ,  93 ,  94 ,  95  and  96  and the sheet-like coil  20  will be explained. 
         [0146]    Coils  91 A,  92 A,  93 A,  94 A,  95 A and  96 A correspond to the coil  22  and the like and have the same structure of the coil  22  and the like. Coil connecting portions  91 S,  92 S,  93 S,  94 S,  95 S and  96 S correspond to the coil connecting portion  22 S and the like and have the same structure as the coil connecting portion  22 S and the like. Further, through hole portions  91 Sh,  92 Sh,  93 Sh,  94 Sh,  95 Sh and  96 Sh correspond to the through hole portions  22 Sh and the like and have the same structure as the through hole portions  22 Sh and the like. 
         [0147]    Further, electrode terminal portions  91 B,  92 B,  93 B,  94 B,  95 B and  96 B correspond to the electrode terminal portion  23  and the like and have the same structure as the electrode terminal portion  23  and the like. Further, through hole portions  91   h ,  92   h ,  93   h ,  94   h ,  95   h  and  96   h  correspond to the through hole portions  23   h  and the like and have the same structure as the through hole portions  23   h  and the like. 
         [0148]    Sheet bodies  91 C,  92 C,  93 C,  94 C,  95 C and  96 C on which coils  91 A,  92 A,  93 A,  94 A,  95 A and  96 A are formed correspond to the sheet body  21  and the like and have the same structure as the sheet body  21 . Further, the insulating sheet for a cover  97  corresponds to the insulating sheet for a cover  60  and has the same structure as the insulating sheet for a cover  60 . 
         [0149]      FIG. 9  is a plain view showing the coil unit  90  in which sheet-like coils  91 ,  92 ,  93 ,  94 ,  95  and  96 , and the insulating sheet for a cover  97  are laminated. 
         [0150]    The hole portion  90 A corresponds to the hole portion  70 A and the concave portion  90 B corresponds to the concave portion  70 B. 
         [0151]    The coil  91 A is connected to the coil  92 A via the coil connecting portion  92 S to be formed as a singularly linked coil. Further, the electrode terminal portion  91 B placed on the top and left side and the electrode terminal portion  92 B placed on the top and right side become electrode terminal portions for the coils  91 A and  92 A singularly linked together. 
         [0152]    The coil  93 A is connected to the coil  94 A via the coil connecting portion  94 S to be formed as a singularly linked coil. Further, the electrode terminal portion  93 B placed on the left side which is a center along upper and lower directions and the electrode terminal portion  94 B placed on the right side which is a center along upper and lower directions become electrode terminal portions for the coils  93 A and  94 A singularly linked together. 
         [0153]    The coil  95 A is connected to the coil  96 A via the coil connecting portion  96 S to be formed as a singularly linked coil. Further, the electrode terminal portion  95 B placed on the lower and left side and the electrode terminal portion  96 B placed on the lower and right side become electrode terminal portions for the coils  95 A and  96 A singularly linked together. 
         [0154]    Further, in the coil unit  90  where sheet-like coils  91 ,  92 ,  93 ,  94 ,  95  and  96 , and the insulating sheet for a cover  97  are laminated, the electrode terminal portions  96 B placed on the top, left and right sides become electrode terminal portions for the coil  91 A and the coil  92 A singularly linked together and the electrode terminal portions  96 B placed on the left and right sides which are a center along upper and lower directions become electrode terminal portions for the coil  93 A and the coil  94 A singularly linked together. Further, the electrode terminal portions  96 B placed on the bottom, left and right sides become electrode terminal portions for the coil  95 A and the coil  96 A singularly linked together so that a three-circuits and six-terminals coil is formed. 
       (Second Modification) 
       [0155]    The flexible coil  10  of the first embodiment described above has a structure in which the winding direction of the first coil is reversed from the winding direction of the second coil. 
         [0156]    In other words, in case of that electrode terminal portions  53 A and  53 C are input terminals and electrode terminal portions  53 B and  53 D are output terminals, the winding direction of the first coil is reversed from the winding direction of the second coil. 
         [0157]    On the other hand, in a coil unit  100  shown in  FIGS. 11 and 12 , the winding direction of the first coil may be the same direction as the winding direction of the second coil. 
         [0158]    The coil unit  100  comprises four sheet-like coils  101 ,  102 ,  103  and  104  shown in  FIGS. 12  (A) to  12  (D) and the insulating sheet for a cover  105  shown in  FIG. 12  (E). 
         [0159]    The coil unit  100  comprises sheet-like coils  101  and  102  singularly linked together and sheet-like coils  103  and  104  singularly linked together. 
         [0160]    Sheet-like coils  101 ,  102 ,  103  and  104  have the same structure as the sheet-like coil  20  and the like. Hence, explanation of details are omitted and only the corresponding parts between sheet-like coils  101 ,  102 ,  103  and  104  and the sheet-like coil  20  and the like will be explained. 
         [0161]    Coils  101 A,  102 A,  103 A and  104 A correspond to the coil  22  and the like and have the same structure as the coil  22  and the like. Coil connecting portions  101 S,  102 S,  103 S and  104 S correspond to the coil connecting portion  22 S and the like and have the same structure as the coil connecting portion  22 S and the like. Further, through hole portions  101 Sh,  102 Sh,  103 Sh and  104 Sh correspond to the through hole portions  22 Sh and the like and have the same structure as the through hole portions  22 Sh and the like. 
         [0162]    Further, in the coil unit  20 , the winding directions of the coil  22  and the coil  32  are clockwise from the left side and the winding directions of the coil  42  and the coil  52  are counter clockwise from the left side. On the other hand, in the coil unit  100 , the winding directions of the coils  101 A and  102 A and the coils  103 A and  104 A are clockwise from the left side. 
         [0163]    Further, electrode terminal portions  101 B,  102 B,  103 B and  104 B correspond to the electrode terminal portion  23  and the like and have the same structure as the electrode terminal portion  23  and the like. Further, through hole portions  101   h ,  102   h ,  103   h  and  104   h  correspond to the through hole portions  23   h  and the like and have the same structure as the through hole portions  23   h  and the like. 
         [0164]    Sheet bodies  101 C,  102 C,  103 C and  104 C on which coils  101 A,  102 A,  103 A and  104 A are formed correspond to the sheet body  21  and the like and have the same structure as the sheet body  21  and the like. Further, the insulating sheet for a cover  105  corresponds the insulating sheet for a cover  60  and has the same structure as the insulating sheet for a cover  60 . 
         [0165]      FIG. 11  is a plain view showing the coil unit  100  in which sheet-like coils  101 ,  102 ,  103  and  104  and the insulating sheet for a cover  105  are laminated. 
         [0166]    The hole portion  100 A corresponds to the hole portion  70 A and the concave portion  100 B corresponds to the concave portion  70 B. 
         [0167]    The coil  101 A is connected to the coil  102 A via the coil connecting portion  102 S to be formed as a singularly linked coil. Further, the electrode terminal portion  101 B placed on the top and left side and the electrode terminal portion  102 B placed on the top and right side become electrode terminal portions for the coils  101 A and  102 A singularly linked together. 
         [0168]    The coil  103 A is connected to the coil  104 A via the coil connecting portion  104 S to be formed as a singularly linked coil. Further, the electrode terminal portion  103 B placed on the lower and left side and the electrode terminal portion  104 B placed on the lower and right side become electrode terminal portions for the coils  103 A and  104 A singularly inked together. 
         [0169]    In the coil unit  100  in which sheet-like coils  101 ,  102 ,  103 ,  104  and the insulating sheet for a cover  105  are laminated, in case of that electrode terminal portions  104 B placed on left, upper and lower sides are input terminals and electrode terminal portions  104 B placed right, upper and lower sides are output terminals, the winding direction of the first coil in which the coils  101 A and  102 A are singularly linked together is the same winding direction as the second coil in which the coils  103 A and  104 A are singularly linked together. 
         [0170]    The present invention is able to be applied to a flexible coil mounted on a flexible substrate.