Patent Publication Number: US-2023133266-A1

Title: Circuit assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority of Japanese Patent Application No. JP 2021-177058 filed on Oct. 29, 2021, the contents of which are incorporated herein. 
     TECHNICAL FIELD 
     The present disclosure relates to a circuit assembly. 
     BACKGROUND 
     Conventional circuit assemblies include a control substrate, a plurality of power supply terminals that supply electric power to the control substrate, and a plurality of busbars that are electrically connected to the power supply terminals, and constitute an electric power circuit (see JP 2019-96769A, for example). As shown in  FIG.  4   , terminals  91  of a conventional circuit assembly  90  are electrically connected to busbars  92  by welding. 
     JP 2019-96769A is an example of related art. 
     SUMMARY 
     In the conventional circuit assembly  90 , the terminals  91  need to be provided with hold-down surfaces  91   a  in order to weld the terminals  91  to the busbars  92 . Therefore, the space for placing the terminals  91  increases, resulting in a larger circuit assembly  90 . 
     Therefore, it is an object of the present disclosure to reduce the size of a circuit assembly. 
     According to an aspect of the present disclosure, a circuit assembly includes a first conductive member; a second conductive member; and a holding member that is insulating and holds the first conductive member and the second conductive member; wherein the first conductive member has a first exposed surface exposed from the holding member, the second conductive member has a second exposed surface exposed from the holding member, the holding member includes an insulating portion located between the first exposed surface and the second exposed surface, and a conductive film covers at least a part of the first exposed surface and at least a part of the second exposed surface, while extending over the insulating portion. 
     According to the present disclosure, it is possible to reduce the size of a circuit assembly. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view illustrating a circuit assembly according to an embodiment; 
         FIG.  2    is a plan view illustrating the circuit assembly; 
         FIG.  3    is an enlarged plan view illustrating the vicinity of power supply terminals; 
         FIG.  4    is a perspective view illustrating a conventional circuit assembly. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     First, embodiments of the present disclosure will be listed and described. 
     A circuit assembly of the present disclosure includes: a first conductive member; a second conductive member; and a holding member that is insulating and holds the first conductive member and the second conductive member; wherein the first conductive member has a first exposed surface exposed from the holding member, the second conductive member has a second exposed surface exposed from the holding member, the holding member includes an insulating portion located between the first exposed surface and the second exposed surface, and a conductive film covers at least a part of the first exposed surface and at least a part of the second exposed surface, while extending over the insulating portion. 
     According to this circuit assembly, since the first conductive member and the second conductive member held by the holding member respectively have the first exposed surface and the second exposed surface exposed from the holding member, and at least a part of the first exposed surface and at least a part of the second exposed surface are covered by the conductive film that extends over the insulating portion, the two exposed surfaces can be electrically connected to each other by the conductive film. With this, there is no need of forming any hold-down surface for welding on one of the first conductive member and the second conductive member, and thus it is possible to downsize that exposed surface. As a result, it is possible to reduce the size of a circuit assembly. 
     Preferably, parts of the first conductive member other than the first exposed surface are buried in the holding member, and parts of the second conductive member other than the second exposed surface are buried in the holding member. 
     In this case, by performing, for example, insert molding to bury a part of the first conductive member and a part of the second conductive member into the holding member, it is easy to form the first exposed surface and the second exposed surface. 
     Preferably, the conductive film is a metal plating film. 
     In this case, it is easy to form the conductive film. 
     Preferably, the first conductive member has a cut-out portion that is cut out and surrounds the second exposed surface. 
     In this case, it is possible to suppress heat generation of the first conductive member that may occur due to a high current, compared to a case where the first conductive member has a hole that surrounds the second exposed surface. 
     Preferably, the first exposed surface and the second exposed surface are coplanar with a surface of the insulating portion that faces the conductive film. 
     In this case, it is possible to form the conductive films more easily. 
     The following will describe details of the embodiment of the present disclosure with reference to the drawings. Note that at least some features of the embodiment described below may be combined with each other as appropriate. 
     Circuit Assembly 
       FIG.  1    is a perspective view showing a circuit assembly  10  according to the present embodiment.  FIG.  2    is a plan view of the circuit assembly  10 . In the following description of the present embodiment, directions such as “up”, “down”, “right”, “left”, “front/forward”, and “rear” are based on the directions indicated in  FIG.  1   . 
     In  FIGS.  1  and  2   , the circuit assembly  10  can be installed in various devices, and the circuit assembly  10  of the present embodiment is installed in a vehicle. More specifically, the circuit assembly  10  is assembled in an electrical junction box disposed at a midway position of a wiring route connecting a not-shown first in-vehicle device and a not-shown second in-vehicle device. The circuit assembly  10  includes a plurality of conductive plates (first conductive members)  11 , a plurality of power supply terminals (second conductive members)  12 , a plurality of control terminals  13 , a plurality of electronic components  14 , and a holding member  15 . The plurality of conductive plates  11 , the plurality of power supply terminals  12 , and the plurality of control terminals  13  constitute an electric power circuit of the circuit assembly  10 . 
     The circuit assembly  10  of the present embodiment includes three conductive plates  11 . The number of conductive plates  11  and the number of power supply terminals  12  are the same, and one conductive plate  11  and one power supply terminal  12  are electrically connected to each other in a one-to-one relationship. Also, the circuit assembly  10  of the present embodiment includes ten control terminals  13 . The number of control terminals  13  and the number of electronic components  14  are the same, and one control terminal  13  and one electronic component  14  are electrically connected to each other in a one-to-one relationship. Note that the numbers of conductive plates  11 , power supply terminals  12 , control terminals  13 , and electronic components  14  are suitably selected, and can be changed as appropriate. 
     The conductive plates  11  are manufactured by pressing a metal plate into a predetermined shape, and are referred to also as “busbars”. The conductive plates  11  are preferably copper members made of, for example, pure copper, a copper alloy, or the like. The entire conductive plates  11  are conductors, and the conductive plates  11  do not have any wiring patterns as formed on a typical printed board. The circuit assembly  10  of the present embodiment includes, as the plurality of conductive plates  11 , a first conductive plate  111 , a second conductive plate  112 , and a third conductive plate  113 . 
     The first conductive plate  111  is arranged at the frontmost position, and extends in a left-right direction. The second conductive plate  112  is arranged behind the first conductive plate  111  at a distance thereto, and extends in the left-right direction. On both front and rear sides of the second conductive plate  112 , a plurality of recesses  112   a  are formed at intervals in the left-right direction (see also  FIG.  3   ). In the present embodiment, on each of the front and rear sides of the second conductive plate  112 , five recesses  112   a  are formed. 
     The third conductive plate  113  includes a conductive body portion  113   a  that extends in the left-right direction, and a conductive extension portion  113   b  that extends forward from a left end portion of the conductive body portion  113   a . The conductive body portion  113   a  is arranged behind the second conductive plate  112  at a distance thereto. A front portion of the conductive extension portion  113   b  extends to a position located on the left side of the first conductive plate  111 . The conductive extension portion  113   b  is arranged on the left side of the first conductive plate  111  and the second conductive plate  112  at a distance thereto. Note that the shapes of the first conductive plate  111 , the second conductive plate  112 , and the third conductive plate  113  are not limited to the shapes employed in the present embodiment. For example, the third conductive plate  113  may be constituted only by the conductive body portion  113   a.    
     The power supply terminals  12  are manufactured by pressing a metal wire material into a predetermined shape. The power supply terminals  12  are terminals made of metal. The power supply terminals  12  are preferably copper members made of, for example, pure copper, a copper alloy, or the like. The power supply terminals  12  are electrically connected to the conductive plates  11  via later-described conductive films  20 , and supply electric power to a not-shown control substrate from the conductive plates  11 . 
     The circuit assembly  10  of the present embodiment includes, as the plurality of power supply terminals  12 , a first power supply terminal  121 , a second power supply terminal  122 , and a third power supply terminal  123 . The first power supply terminal  121  is arranged on the left side of the first conductive plate  111 . The second power supply terminal  122  is arranged on the left side of the second conductive plate  112 . The third power supply terminal  123  is arranged on the right side of an extended conductive portion  113   b  of the third conductive plate  113 . 
     The control terminals  13  are manufactured by pressing a metal wire material into a predetermined shape. The control terminals  13  are terminals made of metal. The control terminals  13  are preferably members made of copper such as, for example, pure copper, a copper alloy, or the like. In the present embodiment, the plurality of control terminals  13  are arranged in the recesses  112   a  formed in the second conductive plate  112  on the front and rear sides. The plurality of control terminals  13  extend downward, and are electrically connected to the control substrate. 
     The electronic components  14  are, for example, semiconductor relays such as field effect transistors (FETs). The following describes a case where the electronic components  14  are field effect transistors, and the field effect transistors are denoted as “FETs”. The plurality of FETs  14  are placed on the first conductive plate  111  and the third conductive plate  113  at intervals in the left-right direction. 
     Each of the FETs  14  includes a plurality of terminals. As shown in an enlarged portion in  FIG.  2   , each FET  14  includes, as the plurality of terminals, a plurality of (four in the illustration) source terminals  14   a , one gate terminal  14   b , and one drain terminal  14   c  (see also  FIG.  3   ). The source terminals  14   a  are electrically connected to the second conductive plate  112  with solder or the like. 
     The gate terminal  14   b  is electrically connected to the corresponding control terminal  13  with solder or the like. The drain terminal  14   c  is electrically connected to the first conductive plate  111  or the third conductive plate  113  with solder or the like. Note that the electronic components  14  may be components other than field effect transistors, and may also be mechanical relays, for example. 
     The holding member  15  is made of a thermoplastic resin. The holding member  15  is made of, for example, PPS (polyphenylene sulfide), PBT (polybutylene terephthalate), nylon, PP (polypropylene), PE (polyethylene), or the like, and is insulating. The holding member  15  of the present embodiment is made of PPS. The holding member  15  is formed by injection molding. In the present embodiment, the holding member  15  is manufactured by insert molding performed with the conductive plates  11 , the power supply terminals  12 , and the control terminals  13  placed in an injection molding die (not shown). With this, the holding member  15  holds the conductive plates  11 , the power supply terminals  12 , and the control terminals  13 . The conductive plates  11 , the power supply terminals  12 , the control terminals  13 , and the holding member  15  serve as an insert-molded article formed in one piece. 
     Exposed Surface 
     The conductive plates  11  each have an exposed surface (first exposed surface) that is exposed from the holding member  15 . Specifically, the first conductive plate  111  has an exposed surface  111   b  that is exposed from the holding member  15  to the upper side. The parts (located below the exposed surface  111   b ) of the first conductive plate  111  other than the exposed surface  111   b  are buried in the holding member  15 . A predetermined number of (five in the illustration) FETs  14  are placed on the exposed surface  111   b . The second conductive plate  112  has an exposed surface  112   c  that is exposed from the holding member  15  to the upper side. The parts (located below the exposed surface  112   c ) of the second conductive plate  112  other than the exposed surface  112   c  are buried in the holding member  15 . 
     The third conductive plate  113  includes an exposed surface  113   d  that is exposed from the holding member  15  to the upper side. The exposed surface  113   d  includes a main exposed surface  113   e  in the conductive body portion  113   a  that is exposed from the holding member  15 , and an extended exposed surface  113   f  in the conductive extension portion  113   b  that is exposed from the holding member  15 . The parts (located below the exposed surface  113   d ) of the third conductive plate  113  other than the exposed surface  113   d  are buried in the holding member  15 . A predetermined number of (five in the illustration) remaining FETs  14  are placed on the exposed surface  113   d.    
       FIG.  3    is an enlarged plan view showing the vicinity of the power supply terminals  12 . In  FIG.  3   , each of the power supply terminals  12  has an exposed surface (second exposed surface) exposed from the holding member  15 . Specifically, the first power supply terminal  121  has an exposed surface  121   a  exposed from the holding member  15  to the upper side. The second power supply terminal  122  has an exposed surface  122   a  exposed from the holding member  15  to the upper side. The third power supply terminal  123  has an exposed surface  123   a  exposed from the holding member  15  to the upper side. The parts (located below the exposed surfaces  121   a ,  122   a , and  123   a ) of the power supply terminals  121 ,  122 , and  123  other than the exposed surfaces  121   a ,  122   a , and  123   a  are buried in the holding member  15 . 
     Cut-Out Portion 
     A cut-out portion  111   a  is formed in a left end portion of the first conductive plate  111 , surrounding the exposed surface  121   a  of the first power supply terminal  121 . The cut-out portion  111   a  of the present embodiment is recess-shaped, opening to the left side thereof. A cut-out portion  112   b  is formed in the corner on the rear left side of the second conductive plate  112 , surrounding the exposed surface  122   a  of the second power supply terminal  122 . The cut-out portion  112   b  of the present embodiment is cut out in an L-shape, opening to the rear and left sides. A cut-out portion  113   c  is formed in a right end portion of the extended conductive portion  113   b  of the third conductive plate  113 , surrounding the exposed surface  123   a  of the third power supply terminal  123 . The cut-out portion  113   c  of the present embodiment is formed recess-shaped, opening to the right side. 
     Insulating Portions 
     In  FIGS.  2  and  3   , the holding member  15  includes, as insulating portions that insulate the exposed surfaces of adjacent conductive plates  11  from each other, a first insulating portion  15   a , a second insulating portion  15   b , and a third insulating portion  15   c . The first insulating portion  15   a  is located between the exposed surface  111   b  of the first conductive plate  111  and the exposed surface  112   c  of the second conductive plate  112 , and insulates the exposed surfaces  111   b  and  112   c  from each other. The second insulating portion  15   b  is located between the exposed surface  112   c  of the second conductive plate  112  and the main exposed surface  113   e  of the third conductive plate  113 , and insulates the exposed surfaces  112   c  and  113   e  from each other. 
     The third insulating portion  15   c  is located between the extended exposed surface  113   f  of the third conductive plate  113 , and the exposed surfaces  111   b  and  112   c  of the first conductive plate  111  and the second conductive plate  112 , and insulates the extended exposed surface  113   f , and the exposed surfaces  111   b  and  112   c  from each other. The third insulating portion  15   c  is coupled to the left ends of the first insulating portion  15   a  and the second insulating portion  15   b.    
     In  FIG.  3   , the holding member  15  includes, as insulating portions that insulate the conductive plates  11  and the exposed surfaces of the power supply terminals  12  from each other, a fourth insulating portion  15   d , a fifth insulating portion  15   e , and a sixth insulating portion  15   f.    
     The fourth insulating portion  15   d  is located between the exposed surface  111   b  of the first conductive plate  111  and the exposed surface  121   a  of the first power supply terminal  121 , and insulates the two exposed surfaces  111   b  and  121   a  from each other. The fourth insulating portion  15   d  of the present embodiment is formed in the cut-out portion  111   a  of the first conductive plate  111 , while being adjacent to the front, right, and rear sides of the exposed surface  121   a  of the first power supply terminal  121 . The fourth insulating portion  15   d  is coupled to the third insulating portion  15   c.    
     The fifth insulating portion  15   e  is located between the exposed surface  112   c  of the second conductive plate  112  and the exposed surface  122   a  of the second power supply terminal  122 , and insulates the two exposed surfaces  112   c  and  122   a  from each other. The fifth insulating portion  15   e  of the present embodiment is formed in the cut-out portion  112   b  of the second conductive plate  112 , while being adjacent to the front and right sides of the exposed surface  122   a  of the second power supply terminal  122 . The fifth insulating portion  15   e  is coupled to the second insulating portion  15   b  and the third insulating portion  15   c.    
     The sixth insulating portion  15   f  is located between the extended exposed surface  113   f  of the third conductive plate  113  and the exposed surface  123   a  of the third power supply terminal  123 , and insulates the two exposed surfaces  113   f  and  123   a  from each other. The sixth insulating portion  15   f  of the present embodiment is formed in the cut-out portion  113   c  of the third conductive plate  113 , while being adjacent to the front, left, and rear sides of the exposed surface  123   a  of the third power supply terminal  123 . The sixth insulating portion  15   f  is coupled to the third insulating portion  15   c.    
     The upper surfaces of the first to third insulating portions  15   a  to  15   c , and the upper surfaces of the fourth to sixth insulating portions  15   d  to  15   f  (the upper surfaces that face the later-described conductive films  20 ) are coplanar. Furthermore, the exposed surfaces  111   b ,  112   c , and  113   d  of the conductive plates  11 , and the exposed surfaces  121   a ,  122   a , and  123   a  of the power supply terminals  12  are coplanar with the upper surfaces of the insulating portions  15   a  to  15   f  of the holding member  15  (see also  FIG.  1   ). 
     Conductive Films 
     The circuit assembly  10  includes a plurality of conductive films  20  that electrically connect the conductive plates  11  to the power supply terminals  12 . The conductive films  20  are deposited by vacuum vapor deposition, for example. The conductive films  20  of the present embodiment are metal plating films in which a nickel plating layer is laminated on a copper plating layer. The circuit assembly  10  of the present embodiment includes, as the plurality of conductive films  20 , a first conductive film  21 , a second conductive film  22 , and a third conductive film  23 . 
     The first conductive film  21  electrically connects the first conductive plate  111  and the first power supply terminal  121 . Specifically, the first conductive film  21  covers a part (left end portion) of the exposed surface  111   b  of the first conductive plate  111  and a part (front end portion) of the exposed surface  121   a  of the first power supply terminal  121  while extending over the fourth insulating portion  15   d.    
     The second conductive film  22  electrically connects the second conductive plate  112  and the second power supply terminal  122 . Specifically, the second conductive film  22  covers a part (left end portion) of the exposed surface  112   c  of the second conductive plate  112  and a part (front end portion) of the exposed surface  122   a  of the second power supply terminal  122  while extending over the fifth insulating portion  15   e.    
     The third conductive film  23  electrically connects the third conductive plate  113  and third power supply terminal  123 . Specifically, the third conductive film  23  covers a part (right end portion) of the extended exposed surface  113   f  of the third conductive plate  113 , and a part (left end portion) of the exposed surface  123   a  of the third power supply terminal  123 , while extending over the sixth insulating portion  15   f.    
     Effects 
     According to the circuit assembly  10  of the present embodiment, the exposed surfaces  111   b ,  112   c , and  113   d  of the conductive plates  11  exposed from the holding member  15  and the exposed surfaces  121   a ,  122   a , and  123   a  of the power supply terminals  12  exposed from the holding member  15  are covered by the conductive films  20  that extends over the insulating portions  15   d ,  15   e , and  15   f , and thus the conductive plates  11  and the power supply terminals  12  are electrically connected by the conductive films  20 . With this, there is no need of forming any hold-down surface for welding on the power supply terminal  12 , making it possible to downsize the exposed surfaces  121   a ,  122   a , and  123   a  of the power supply terminals  12 . As a result, it is possible to reduce the size of the circuit assembly  10 . 
     By insert molding, parts of the conductive plates  11  other than the exposed surfaces  111   b ,  112   c , and  113   d  are buried in the holding member  15 , and parts of the power supply terminals  12  other than the exposed surfaces  121   a ,  122   a , and  123   a  are buried in the holding member  15 . With this, the exposed surfaces  111   b ,  112   c , and  113   d  of the conductive plates  11 , and the exposed surfaces  121   a ,  122   a , and  123   a  of the power supply terminals  12  can be formed easily. 
     The cut-out portions  111   a ,  112   b , and  113   c  are respectively formed in the conductive plates  11 , surrounding the exposed surfaces  121   a ,  122   a , and  123   a  of the power supply terminals  12 . Accordingly, it is possible to suppress heat generation of the conductive plates  11  that may occur due to a high current, compared to a case where the conductive plates  11  have holes that surround the respective power supply terminal  12 . 
     Since the conductive films  20  are metal plating films, it is easy to form the conductive films  20 . Also, by using metal plating films as the conductive films  20 , it is also possible to mount another electronic component on the conductive films  20 . 
     Since the exposed surfaces  111   b ,  112   c , and  113   d  of the conductive plates  11 , the exposed surfaces  121   a ,  122   a , and  123   a  of the power supply terminals  12 , and the upper surfaces of the insulating portions  15   d ,  15   e , and  15   f  are coplanar, it is easy to form the conductive films  20 . 
     Other Considerations 
     Although the conductive films  20  of the present embodiment cover parts of the exposed surfaces (first exposed surfaces)  111   b ,  112   c , and  113   d  of the conductive plates  11 , the conductive films  20  may also cover the entire exposed surfaces  111   b ,  112   c , and  113   d . Also, although the conductive films  20  cover parts of the exposed surfaces (second exposed surfaces)  121   a ,  122   a , and  123   a  of the power supply terminals  12 , the conductive films  20  may also cover the entire exposed surfaces  121   a ,  122   a , and  123   a . The conductive films  20  of the present embodiment are deposited by vacuum vapor deposition. But the present disclosure is not limited to this, and the conductive films  20  may also be deposited by, for example, sputtering, printing, or the like. 
     The embodiments disclosed herein are to be construed as being exemplary and non-limiting in all respects. The scope of the present disclosure is not defined by the description above but is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.