Patent Publication Number: US-9431720-B2

Title: Connecting structure and connecting method of flat circuit body and terminal

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of PCT application No. PCT/JP2013/051361, which was filed on Jan. 17, 2013 based on Japanese Patent Application (No. 2012-008070) filed on Jan. 18, 2012, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to a connecting structure and a connecting method of a flat circuit body and a terminal in which the terminal is crimped to connect to a conductor of the flat circuit body which is formed to a planar wiring member by at least covering the surfaces at one side of a plurality of conductors, which are separated at a predetermined interval and arranged into a planar shape, with insulating layers. 
     2. Description of the Related Art 
     A wiring member which has flexibility such as an FPC (Flexible Printed Circuit), an FFC (Flexible Flat Cable) or a ribbon electric wire corresponds to the flat circuit body. 
       FIGS. 17 and 18  show a conventional example of connecting structure of a flat circuit body and terminals. 
     The connecting structure of a flat circuit body and terminals is disclosed in the following patent document 1. In the connecting structure, as shown in  FIG. 17 , two overlapped terminal connecting parts  111  are formed by folding a middle part of the flat circuit body  110  beforehand. 
     A terminal  120  which connects to the flat circuit body  110  is a press formed article which is made of a metal plate, and includes a terminal fitting part  121  with which a mating terminal is fitted and connected, and a circuit body connecting part  122  to connect the flat circuit body  110 , as shown in  FIG. 17 . 
     The circuit body connecting part  122  includes a bottom plate  122   a  on which the flat circuit body  110  is mounted, and crimp claws  122   b  which are raised at two side edges of the bottom plate  122   a . The bottom plate  122   a  is formed into a belt shape whose width is narrower than a width w 1  (refer to  FIG. 18 ) of conductors  112  in the flat circuit body  110 . The distal end of the crimp claw  122   b  is formed into a pointed shape so that the conductors  112  of the two overlapped terminal connecting parts  111  are penetrated therethrough. 
     In the connecting structure in PTL 1, after making the crimp claws  122   b  penetrate the conductor  112  of the terminal connecting parts  111  of the flat circuit body  110 , by crimping the distal ends of the crimp claws  122   b  that project from the terminal connecting parts  111  to fold on the terminal connecting parts  111 , a state that the terminals  120  are crimped to connect to the conductors  112  is reached. 
     CITATION LIST 
     Patent Literature 
     [PTL 1] JP-A-2004-221044 
     SUMMARY OF THE INVENTION 
     In the connecting structure in PTL 1, the crimp claws  122   b  penetrate through the conductors  112  of the flat circuit body  110  to electrically connect the conductors  112  and the terminals  120  with the contact in the penetrated parts. However, the conductors  112  of the flat circuit body  110  are damaged due to the penetration of the crimp claws  122   b , and when a pulling load is applied on the flat circuit body  110 , the damages expand, and electrical connection performance may decrease due to the increase of contact resistance with the expansion of the damages. 
     Further, in the crimping step of the crimp claws  122   b , a jig (forming die) which bends the distal ends of the crimp claws  122   b  on the flat circuit body  110  is usually used. When the jig is a forming die to shape the crimp claws  122   b  to a curved form (curl form) so that the distal ends of the crimp claws  122   b  come in contact with the flat circuit body  110 , in order to control a crimping pressure or precisely control the height of the crimp claws  122   b  after being shaped so that the distal ends of the crimp claws  122   b  will not excessively damage the conductors  112 , force increasing or decreasing which is difficult in a crimping operation is required, and there is a problem that operativity is hard to be improved. 
     It is therefore one advantageous aspect of the present invention to provide a connecting structure and a connecting method of a flat circuit body and a terminal so that the electrical connection performance does not decrease because the conductors of the flat circuit body are damaged by a pulling load that is applied on the flat circuit body, and a stable electrical connection performance can be easily secured without requiring the force increasing or decreasing which is difficult in a crimping operation of the terminal. 
     According to one advantage of the invention, there is provided a connecting structure of a flat circuit body and a terminal, comprising: 
     a flat circuit body including a conductor and an insulating layer covering at least one of surfaces of the conductor, a portion of the conductor being exposed from the insulating layer; 
     a terminal including a bottom plate on which the exposed portion of the conductor is provided, and crimp claws which are raised at two side edges of the bottom plate so that the exposed portion of the conductor is disposed therebetween; and 
     a protective plate, provided on the exposed portion of the conductor, and having a strength so as not to be penetrated by the crimp claws when the crimp claws are crimped onto the protective member, 
     wherein the crimp claws are crimped onto the protective plate so that the terminal is crimped to the conductor in a state where the exposed portion of the conductor is in surface contact with the bottom plate, and 
     distal ends of the crimp claws which press the protective plate are in a surface contact with the protective plate in a folded form. 
     The flat circuit body may include a plurality of conductors which are arranged in a planar shape with separated at a predetermined interval. 
     According to the present invention, the crimp claws of the terminal are crimped to the protective plate which is overlaid on the conductor exposed portion of the flat circuit body, and by pressing the protective plate to the side of the bottom plate of the terminal, to make the conductor in the conductor exposed portion to be in a surface contact with the bottom plate of the terminal, a crimped state of the conductor of the flat circuit body and the terminal is reached. That is, the crimp claws of the terminal will not penetrate through the conductor of the flat circuit body, and since the distal ends of the claws do not cut into the conductor, the crimp claws will not damage the conductor. 
     Therefore, even if a pulling load is acted on the flat circuit body, the damage will not expand in the conductor as traditionally, and there is no fear that electrical connection performance decreases due to the increase of contact resistance with the expansion of the damage in the conductor. 
     In addition, in the construction that the crimp claws press the conductor of the conductor exposed portion to the bottom plate of the terminal through the protective plate, since the crimp claws do not directly contact with the conductor exposed portion, the force increasing or decreasing which is difficult in a crimping operation of the terminal is not required. Therefore, the crimping operation can be performed easily. 
     Therefore, a stable electrical connection performance can be easily secured. 
     According to the invention, the electrical connection performance does not decrease when the conductor of the flat circuit body is damaged by a pulling load acted on the flat circuit body, and the force increasing or decreasing which is difficult in a crimping operation of the terminal is not required so that a stable electrical connection performance can be easily secured. 
     According to the invention, the sides of the distal ends of the crimp claws which press the protective plate are in a surface contact with the protective plate in a folded form. Because of the resilience (recovery power) possessed (accumulated) in the folded parts, when compared to the structure that the crimp claws simply abut with the protective plate in the form of one fold, the pressing force to the protective plate can be prevented from decreasing by a spring back of the crimp claws, and a stable electrical connection performance can be maintained for a longer term. 
     According to the crimp connecting structure and the crimp connecting method of the terminal and the flat circuit body of the present invention, the crimp claws of the terminal are crimped to the protective plate which is overlaid on the conductor exposed portion of the flat circuit body, and by pressing the protective plate to the side of the bottom plate of the terminal, to make the conductor in the conductor exposed portion to be in a surface contact with the bottom plate of the terminal, a crimped state of the conductor of the flat circuit body and the terminal is reached. That is, the crimp claws of the terminal will not penetrate through the conductor of the flat circuit body, and since the distal ends of the claws do not cut into the conductor, the crimp claws will not damage the conductor. 
     Therefore, even if a pulling load is applied on the flat circuit body, the damage will not expand in the conductor as traditionally, and there is no fear that electrical connection performance decreases due to the increase of contact resistance with the expansion of the damage in the conductor. 
     In addition, in the construction that the crimp claws press the conductor of the conductor exposed portion to the bottom plate of the terminal through the protective plate, since the crimp claws do not directly contact with the conductor exposed portion, the force increasing or decreasing which is difficult in a crimping operation of the terminal is not required. Therefore, the crimping operation can be performed easily. 
     Therefore, a stable electrical connection performance can be easily secured. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view which shows the structure of a conductor exposed portion of a flat circuit body used in a connecting structure of the flat circuit body and a terminal according to one embodiment of the present invention. 
         FIG. 2  is a perspective view which shows that a protective plate is mounted on the conductor exposed portion shown in  FIG. 1 . 
         FIG. 3  is an A-A sectional view of  FIG. 2 . 
         FIG. 4  is a perspective view which shows a state that the conductor exposed portion and the protective plate of  FIG. 2  are mounted on a bottom plate of the terminal. 
         FIG. 5  is a B-B sectional view of  FIG. 4 . 
         FIG. 6  is an illustrative figure of a structure of the end side of the bottom plate of crimp claws of the terminal shown in  FIG. 5 . 
         FIG. 7  is a perspective view which shows a completed connection state that the crimp claws are crimped on the protective plate from the state shown in  FIG. 4 . 
         FIG. 8  is a C-C sectional view of  FIG. 7 . 
         FIG. 9  is an illustrative figure which shows a state that the crimp claws are further crushed from the state of  FIG. 8 . 
         FIG. 10  is a perspective view which shows another embodiment of conductor exposed portion in the flat circuit body according to the present invention. 
         FIG. 11  is a figure which shows bottom plate and crimp claws of the terminal according to the present invention, and is an expanded view of the embodiment in which the shape of serrations is changed. 
         FIG. 12  is a figure which shows another embodiment of bottom plate and crimp claws of the terminal according to the present invention, and is an expanded view of the embodiment in which the serrations are omitted and replaced with a simple flat smooth surface. 
         FIG. 13  is a perspective view which shows another embodiment of conductor exposed portion of the flat circuit body according to the present invention. 
         FIG. 14  is a cross sectional view of the conductor exposed portion in a state that a protective plate is mounted on an insulating layer of the conductor exposed portion shown in  FIG. 13 . 
         FIG. 15  is a cross sectional view which shows a state that the conductor exposed portion shown in  FIG. 14  is mounted on the bottom plate of an end of the terminal. 
         FIG. 16  is a cross sectional view of the end of the terminal in a state that the crimp claws are crimped to the conductor exposed portion shown in  FIG. 15 . 
         FIG. 17  is an exploded perspective view of a traditional connecting structure of a flat circuit body and a terminal. 
         FIG. 18  is a perspective view which shows a state after the connection of the flat circuit body and the terminal shown in  FIG. 17  is completed. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
       FIGS. 1 to 9  show an embodiment of connecting structure and connecting method of a flat circuit body and a terminal according to the present invention.  FIG. 1  is a perspective view which shows the structure of a conductor exposed portion of the flat circuit body used in the embodiment of the present invention.  FIG. 2  is a perspective view which shows that a protective plate is mounted on the conductor exposed portion shown in  FIG. 1 .  FIG. 3  is an A-A sectional view of  FIG. 2 .  FIG. 4  is a perspective view which shows a state that the conductor exposed portion and the protective plate of  FIG. 2  are mounted on a bottom plate of the terminal.  FIG. 5  is a B-B sectional view of  FIG. 4 .  FIG. 6  is an illustrative figure of a structure of the end side of the bottom plate of crimp claws of the terminal shown in  FIG. 5 .  FIG. 7  is a perspective view which shows a completed connection state that the crimp claws are crimped on the protective plate from the state shown in  FIG. 4 .  FIG. 8  is a C-C sectional view of  FIG. 7 .  FIG. 9  is an illustrative figure which shows a state that the crimp claws are further crushed from the state of  FIG. 8 . 
       FIG. 1  shows a flat circuit body  10  to which terminals are crimped to connect in a connecting structure of one embodiment of the present invention. 
     The flat circuit body  10  is manufactured to a planar wiring member by covering a plurality of conductors  11 , which are separated at a predetermined interval and arranged into a planar shape, with insulating layers  12 . In particular, a wiring member which has flexibility such as an FPC Flexible Printed Circuit), an FFC (Flexible Flat Cable) or a ribbon electric wire corresponds to the flat circuit body  10 . The flat circuit body  10  corresponds to, for example, a flat circuit body in which surfaces at both sides of the conductors  11  are covered with insulating layers  12 , and the conductors  11  are exposed by stripping a part of the insulating layers  12  of the surfaces at one side, a flat circuit body in which surfaces at one side of the conductors  11  are covered with insulating layers  12  and the other surfaces are exposed, or a flat circuit body in which surfaces at one side of the conductors  11  are covered with insulating layers  12 , and a part of the surfaces at the other side are further covered with insulating layers  12 . 
     In the present embodiment, a conductor exposed portion  13  shown in  FIG. 1  is formed in the flat circuit body  10  beforehand. The conductor exposed portion  13  is a portion where the conductors  11  are exposed by stripping the insulating layers  12 . In  FIG. 1 , the insulating layers  12  located between adjacent conductors  11  are removed and the insulating layers  12  covering the surfaces at one side of the conductors  11  are stripped so that the conductors  11  reach a state of exposing the surfaces at one side. 
     In this embodiment, a protective plate  20  shown in  FIG. 2  is prepared. The protective plate  20  is a flat board-like member which has such a strength that the crimp claws of the terminal  30  to be described below will not pierce. It does not mind whether the material of the protective plate  20  is a conductive material or an insulating material. The protective plate  20  is a rectangular board having a width roughly the same as that of the conductors  11 , and as shown in  FIGS. 2 to 5 , is placed to be overlaid on the conductor exposed portion  13  mounted on the terminal  30  to be described below. 
     The terminal  30  which is crimped to connect to the flat circuit body  10  is a press formed article that is made of a metal plate, and as shown in  FIG. 4 , includes a generally square pipe-like terminal fitting part  31  with which a mating terminal is fitted and connected, and a circuit body connecting part  32  to connect the flat circuit body  10 . 
     The circuit body connecting part  32  includes a bottom plate  32   a  on which the flat circuit body  10  is mounted, and crimp claws  32   b  which are raised at two side edges of the bottom plate  32   a . The bottom plate  32   a  is adapted to be able to carry the conductor  11  of a width w 3  (refer to  FIG. 5 ) in the flat circuit body  10 . On the surface of the bottom plate  32   a  on which the conductor exposed portion  13  is mounted, as shown in  FIG. 6 , groove-like serrations  32   c  are formed. 
     Each of the crimp claws  32   b  which extend from two side edges of the bottom plate  32   a  is a part that is crimped to the conductor exposed portion  13  which is mounted on the bottom plate  32   a . In a crimping step of crimping and shaping the crimp claws  32   b , a crimp jig (forming die) that makes the crimp claws  32   b  to be curved from the distal end side of the crimp claws  32   b  to make the distal ends  321  of the crimp claws  32   b  come in contact with the surface of the protective plate  20  is used, although the crimp jig is not shown in the figures. 
     For the connecting structure of the flat circuit body and the terminal in the present embodiment, first, as shown in  FIGS. 4 and 5 , the protective plate  20  is mounted on the conductor exposed portion  13  which is mounted on the bottom plate  32   a  in a direction that the conductor  11  exposed in the conductor exposed portion  13  meets the bottom plate  32   a , and by crimping the crimp claws  32   b  from above the protective plate  20  to make the conductor  11  closely contact with the bottom plate  32   a  in a surface contact state through the protective plate  20 , as shown in  FIGS. 7 and 8 , a crimped state of the conductor  11  and the terminal  30  is reached. 
     Further, for the connecting structure of the present embodiment, when the crimp claws  32   b  are crimped and shaped, as shown in  FIG. 8 , the distal ends  321  of the crimp claws  32   b  are bended to the base ends of the crimp claws so that the crimp claws are shaped into such a bended shape that those part in predetermined length ranges H (refer to  FIG. 8 ) from the distal ends  321  are folded and in a surface contact with the protective plate  20 . 
     A connecting method to obtain the connecting structure of the present embodiment sequentially performs a conductor exposed portion forming step, a circuit body mounting step and a crimping step shown as follows. 
     The conductor exposed portion forming step is a step of forming the conductor exposed portion  13  in the flat circuit body  10  which is manufactured to a planar wiring member by covering a plurality of conductors  11 , which are separated at a predetermined interval and arranged into a planar shape, with the insulating layers  12 , by stripping the insulating layers  12  to expose the conductors  11 , as shown in  FIG. 1 . When a flat circuit body  10  in which a part of the conductors  11  are exposed beforehand is used, the conductor exposed portion forming step is omitted. 
     The circuit body mounting step is a step of mounting the conductor exposed portion  13  on the bottom plate  32   a  in a direction that the conductor  11  exposed in the conductor exposed portion  13  meets the bottom plate  32   a  of the terminal  30 , as shown in  FIGS. 4 and 5 . 
     The crimping step is a step of crimping the crimp claws  32   b  at two side edges of the bottom plate  32   a  onto the protective plate  20  in a state that the above-mentioned protective plate  20  is overlaid on the conductor exposed portion  13  mounted on the bottom plate  32   a , to press the protective plate  20  to the side of the bottom plate  32   a  to make the conductor  11  closely contact with the bottom plate  32   a  in a surface contact state through the protective plate  20  so that the conductor  11  and the bottom plate  32   a  are in a crimped connection state. 
     In the crimping step, as a means for crimping the crimp claws  32   b  to the protective plate  20 , a crimp jig which makes the crimp claws  32   b  to be curved from the distal ends to come in contact with the protective plate  20  is used. 
     Further, in the crimping step, as shown in  FIG. 8 , the distal ends  321  of the crimp claws  32   b  are bended to the base ends of the crimp claws  32   b  so that the crimp claws are shaped into such a bended shape that those part in the predetermined length ranges H from the distal ends  321  are folded and in a surface contact with the protective plate  20 . 
     In the present embodiment, when cavities S remain inside the crimp claws  32   b  which are in a surface contact with the protective plate  20  as shown in  FIG. 8 , the crimp claws  32   b  are further crushed by the crimp jig to get a structure that there is no cavity S as shown in  FIG. 9 , so that the height K of the crimped parts is further lowered, and downsizing becomes possible. 
     For the connecting structure of the flat circuit body and the terminal of the embodiment described above, the crimp claws  32   b  of the terminal  30  are crimped to the protective plate  20  which is overlaid on the conductor exposed portion  13  of the flat circuit body  10 , and by pressing the protective plate  20  to the side of the bottom plate  32   a  of the terminal  30 , to make the conductor  11  in the conductor exposed portion  13  closely contact with the bottom plate  32   a  of the terminal  30  in a surface contact state, a crimped state of the conductor  11  of the flat circuit body  10  and the terminal  30  is reached. That is, the crimp claws  32   b  of the terminal  30  will not penetrate through the conductor  11  of the flat circuit body  10 , and since the distal ends of the claws do not cut into the conductor  11 , the crimp claws  32   b  will not damage the conductor  11 . 
     Therefore, even if a pulling load is applied on the flat circuit body  10 , the damage will not expand in the conductor  11  as traditionally, and there is no fear that electrical connection performance decreases due to the increase of contact resistance with the expansion of the damage in the conductor  11 . 
     In addition, in the construction that the crimp claws  32   b  press the conductor  11  of the conductor exposed portion  13  to the bottom plate  32   a  of the terminal  30  through the protective plate  20 , since the crimp claws  32   b  do not directly contact with the conductor exposed portion  13 , the force increasing or decreasing which is difficult in a crimping operation of the terminal  30  is not required. Therefore, the crimping operation can be performed easily. 
     Therefore, a stable electrical connection performance can be easily secured. 
     Further, by performing the previous steps in the connecting method, the connecting structure of the present embodiment can be formed. Therefore, there is no fear that the electrical connection performance decreases when the conductor  11  of the flat circuit body  10  is damage by a pulling load applied on the flat circuit body  10 , and the force increasing or decreasing which is difficult in a crimping operation of the terminal  30  is not required so that a stable electrical connection performance can be easily secured. 
     In the connecting structure and the connecting method in the present embodiment, the sides of the distal ends  321  of the crimp claws  32   b  which press the protective plate  20  are in a surface contact with the protective plate  20  in a folded form as shown in  FIGS. 8 and 9 . Because of the resilience (recovery power) possessed (accumulated) in the folded parts, when compared to the structure that the crimp claws simply come in contact with the protective plate  20  in the form of one fold, the pressing force to the protective plate  20  can be prevented from decreasing by a spring back of the crimp claws  32   b , and a stable electrical connection performance can be maintained for a longer term. 
     In the connecting structures and the connecting methods of the present invention, the specific structure of the conductor exposed portion  13  formed in the flat circuit body  10  is not limited to the structure of  FIG. 1 . 
       FIG. 10  shows another embodiment of conductor exposed portion  13  to which the terminal  30  shown in  FIG. 4  is crimped to connect. In this embodiment, the conductor exposed portion  13  is not at an end of the flat circuit body  10 , but is formed at a middle part of the flat circuit body  10 . Further, insulating layers  12  on the front and back surfaces of the conductors  11  are stripped. 
     In the connecting structures and the connecting methods of the present invention, the shape of the serrations which are formed on the inner surface of the bottom plate  32   a  and the crimp claws  32   b  in the circuit body connecting part  32  of the terminal  30  is not limited to that shown in  FIG. 6 . The serrations  32   c  that are formed on the inner surface of the bottom plate  32   a  and the crimp claws  32   b  may be circular recesses as shown in  FIG. 11 . As shown in  FIG. 12 , the inner surface of the bottom plate  32   a  and the crimp claws  32   b  may be a flat smooth surface on which the serrations are not formed. 
     In the connecting structures and the connecting methods of the present invention, the conductor exposed portion  13  formed in the flat circuit body  10  may have such a construction that when only the insulating layers  12  of the surfaces at one side of the conductors  11  are stripped and the insulating layers  12  of the surfaces at the other side remain, the insulating layers  12  between adjacent conductors  11  are left, as shown in  FIGS. 13 and 14 . In this case, as shown in  FIGS. 15 and 16 , by providing claw through holes  14  into which the crimp claws  32   b  are inserted in the insulating layers  12  between adjacent conductors  11  beforehand, the conductor exposed portion  13  can be easily mounted onto the circuit body connecting part  32 . 
     In the above-mentioned embodiments, the protective plate  20  is a separate member from the terminal  30 , but the terminal  30  may be integrally equipped with the protective plate  20 . 
     According to the present invention, there is provided a connecting structure and a connecting method of a flat circuit body and a terminal so that the electrical connection performance does not decrease because the conductors of the flat circuit body are damaged by a pulling load that is applied on the flat circuit body, and a stable electrical connection performance can be easily secured without requiring the force increasing or decreasing which is difficult in a crimping operation of the terminal.