Patent Publication Number: US-2022239086-A1

Title: Busbar assembly and method for manufacturing the same

Description:
FIELD OF THE INVENTION 
     The present invention relates to a busbar assembly in which a plurality of busbars are electrically insulated and mechanically connected to one another, and a method for manufacturing the same. 
     BACKGROUND ART 
     Busbar assemblies in which a plurality of busbars are mutually electrically insulated and mechanically connected are proposed, and are used in various fields. 
     For example, there are proposed laminated-type busbar assemblies in which a first flat plate busbar and another second flat plate busbar in parallel with each other are vertically laminated (see Patent Literatures 1 and 2 below). 
     In the laminated-type busbar assembly, the entirety of the opposing flat surface of the first flat plate busbar and the entirety of the opposing flat surface of the second flat plate busbar are disposed to face each other with an insulating resin therebetween, it is difficult to ensure sufficient reliability in electric insulating property. 
     In particular, if the insulating resin between the first and second flat plate busbars is made thin in order to downsize the busbar assembly in the vertical direction, there is a risk that a leakage current flows between the first and second busbars. 
     In order to solve the problems of the above laminated-type busbar assembly, the present applicant has filed applications for a planar-type busbar assembly in which first and second busbars of conductive metal flat plates are arranged in parallel in a common plane (see Patent Literatures 3 and 4 below). 
       FIG. 19A  shows a plan view of an example of a planar-type busbar assembly  500 . 
       FIG. 19B  shows a cross-sectional view along the line XIX(b)-XIX(b) in  FIG. 19A . 
     As shown in  FIGS. 19A and 19B , the planar-type busbar assembly  500  has a first busbar  510   a  formed of a conductive metal flat plate, a second busbar  510   b  formed f a conductive metal flat plate and arranged in the same plane as the first busbar  510   a  with a gap  515  between the first busbar  510   a  and the second busbar  510   b , and an insulative resin layer  520  that mechanically connects the first and second busbars  510   a ,  510   b  while electrically insulating them. 
     The insulative resin layer  520  has a gap filling part  525  filled in the gap  515 , and a surface laminate part laminated on a surface of a busbar connection body where the first and second busbars  510   a ,  510   b  are connected by the gap filling part  525 . 
     The surface laminate part includes a first surface-side laminate part  530  and a second surface-side laminate part  540  that cover a first surface on one side in the thickness direction and a second surface on the other side in the thickness direction of the busbar connection body, respectively, and a side surface-side laminate part  550  that covers an outside surface of the busbar connection body and connects the first and second surface-side laminate parts  530 ,  540 . 
     The first surface-side laminate part  530  has first and second openings  531   a ,  531   b  that expose predetermined parts of the first surfaces of the first and second busbars  510   a ,  510   b , respectively, thereby to form first and second exposure regions. 
       FIG. 19C  shows a vertical cross-sectional view of a semiconductor module  600  in which a semiconductor element  110  such as an LED is mounted on the busbar assembly  500 . 
     As shown in  FIG. 19C , the semiconductor element  110  has a first electrode layer (lower electrode layer) mechanically and electrically connected to one of the first and second exposure regions (in  FIG. 19C , the first exposure region) via, for example, a plating layer (not shown), and a second electrode layer (upper electrode layer) electrically connected to the other of the first and second exposure regions (the second exposure region in  FIG. 19C ) via a wire bonding  120 . 
       FIGS. 20A to 20D  show a process flow chart of an example of a manufacturing method of the above planar-type busbar assembly  500 . 
     The manufacturing method includes a processes of arranging the first and second busbars  510   a ,  510   b  in the common plane with the gap  515  ( FIG. 20A ), applying an insulative resin member in the gap  515  and on the surfaces of the first and second busbars  510   a ,  510   b , and curing the insulative resin member thereby to form the insulative resin layer  520  ( FIG. 20B ), and providing the first and second openings  531   a  and  531   b  by performing laser beam machining to the first surface-side laminate part  530  of the insulative resin layer  520  ( FIGS. 20C  and D). 
       FIG. 20E  shows an enlarged view of the part XX(e) in  FIG. 20D . 
     Here, in order to reduce the size of the semiconductor module  600  including the semiconductor element  110  with respect to the plate surface direction (planar direction), it is necessary to make the edges of the first and second openings  531   a  and  531   b  on the side proximate to the gap  515  as close as possible to or match the boundaries of the corresponding busbars  510   a  and  510   b  and the gap  515 . 
     In order to do so, it is necessary to perform laser beam machining so that, when forming the first and second openings  531   a ,  531   b , the edge of the first opening  531   a  on the side proximate to the gap  515  should be as close as possible to the end part (inner end part) of the first busbar  510   a  on the side proximate to the gap  515 , and the edge of the second opening  531   b  on the side proximate to the gap  515  should be as close as possible to the end part (inner end part) of the second busbar  510   b  on the side proximate to the gap  515  (see  FIGS. 21A and 21B ). 
       FIG. 21C  shows an enlarged view of the part XXI(c) in  FIG. 21B . 
     However, when the laser beam machining is performed in this manner, as shown in  FIG. 21C , a part of the gap filling part  525  is melted by the laser beam, and a pinhole  527  may be generated in the gap filling part  525 . 
     The pinhole  527  leads to deterioration of the insulation performance and the connection strength between the first and second busbars  510   a ,  510   b.    
     PRIOR ART DOCUMENT 
     Patent Literature 
     Patent Literature 1: Japanese Patent No. 4432913 
     Patent Literature 2: Japanese Patent No. 6487769 
     Patent Literature 3: Japanese Patent Publication No. 2019-042678 
     Patent Literature 4: Japanese Patent Publication No. 2019-050090 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the conventional art, and it is an object of the present invention to provide a busbar assembly including a plurality of busbars arranged in the common plane with a gap present between adjacent busbars, and an insulative resin layer including a gap filling part filled in the gap and a first surface-side laminate part provided on a first surface on one side in a thickness direction of a busbar connection body where the plurality of busbars are connected by the gap filling part, the first surface-side laminate part having a plurality of first surface-side center openings that respectively expose a predetermined part of the first surface of the plurality of busbars, wherein the busbar assembly can cause an edge of the first surface-side center opening on a side proximate to the gap to be arranged as close as possible to or match a boundary between the corresponding busbar and the corresponding gap. 
     It is also an object of the present invention to provide a manufacturing method that can efficiently manufacture the above busbar assembly. 
     In order to achieve the object, a first aspect of the present invention provides a busbar assembly including a plurality of busbars each formed by a conductive flat plate member and disposed in a common plane with a gap provided between adjacent busbars, and an insulative resin layer including a gap filling part filled into the gap and a first surface-side laminate part provided on a first surface on one side in a plate thickness direction of a busbar connection body in which the plurality of busbars are connected to one another by the gap filling part, wherein the first surface-side laminate part has a plurality of first surface-side center openings that expose predetermined parts of the first surfaces of the plurality of busbars, respectively, to form a plurality of exposure regions, and wherein the insulative resin layer being formed by an insulative resin material that is transparent in a half-cured state and nontransparent in a completely cured state. 
     The busbar assembly according to the first aspect of the present invention includes the plurality of busbars disposed in the common plane with the gap provided between the adjacent busbars, and the insulative resin layer including the gap filling part filled into the gap and the first surface-side laminate part provided on the first surface on one side in the plate thickness direction of the busbar connection body in which the plurality of busbars are connected to one another by the gap filling part, wherein the first surface-side laminate part is formed with the plurality of first surface-side center openings that expose predetermined parts of the first surfaces of the plurality of busbars, respectively, to form the plurality of exposure regions, and wherein the insulative resin layer is formed by the insulative resin material that is transparent in a half-cured state and nontransparent in a completely cured state. 
     According to the busbar assembly, it is possible to make the edge of the first surface-side center opening on the side proximate to the gap substantially coincident with or as close as possible to the boundary of the corresponding busbar and the corresponding gap while effectively preventing or reducing generation of pinholes in the gap filling part by irradiating a laser beam to a laser area including first surface-side center opening formation areas that correspond to the plurality of first surface-side center openings and that are adjacent to each other with the gap being therebetween and an intermediate area sandwiched between the adjacent first surface-side center opening formation areas in a state that the insulative resin material provided on the entirety of the first surface of the busbar connection body is half-cured. Accordingly, it is possible to have a semiconductor element, which is mounted on the busbar assembly, arranged as close as possible to the gap while maintaining insulation property and connection strength between the adjacent busbars. 
     In a preferable embodiment, each of edges of the plurality of first surface-side center openings on a side proximate to the corresponding gap is aligned with a boundary between the corresponding busbar and the corresponding gap. 
     In a preferable embodiment, the first surface-side laminate part may be configured to have a partition wall part extending from the gap filling part outward toward one side in the thickness direction of the busbar connection body at an area sandwiched by the first surface-side center openings that are adjacent to each other with the gap being sandwiched therebetween. 
     Further, a second aspect of the present invention provides a busbar assembly including a plurality of busbars each formed by a conductive flat plate member and disposed in a common plane with a gap provided between adjacent busbars, and an insulative resin layer including a gap filling part filled into the gap and a first surface-side laminate part provided on a first surface on one side in a plate thickness direction of a busbar connection body in which the plurality of busbars are connected to one another by the gap filling part, wherein the first surface-side laminate part has a plurality of first surface-side center openings that expose predetermined parts of the first surfaces of the plurality of busbars, respectively, to form a plurality of exposure regions, and wherein the first surface-side laminate part has a partition wall part extending from the gap filling part outward toward one side in the thickness direction of the busbar connection body at an area sandwiched by the first surface-side center openings that are adjacent to each other with the gap being sandwiched therebetween. 
     The busbar assembly according to the second aspect of the present invention includes the plurality of busbars disposed in the common plane with the gap provided between the adjacent busbars, and the insulative resin layer including the gap filling part filled into the gap and the first surface-side laminate part provided on the first surface on one side in the plate thickness direction of the busbar connection body in which the plurality of busbars are connected to one another by the gap filling part, wherein the first surface-side laminate part is formed with the plurality of first surface-side center openings that expose predetermined parts of the first surfaces of the plurality of busbars, respectively, to form the plurality of exposure regions, and wherein the first surface-side laminate part has a partition wall part extending from the gap filling part outward toward one side in the thickness direction of the busbar connection body at an area sandwiched by the first surface-side center openings that are adjacent to each other with the gap being sandwiched therebetween. 
     According to the busbar assembly, it is possible to use the partition wall part as a stopper when mounting the semiconductor element directly or indirectly via a plating layer on the region exposed through the first surface-side center opening. 
     Accordingly, it is possible to have the semiconductor element arranged as close as possible to the gap while effectively preventing the semiconductor, which is mounted on one of the adjacent busbars, from unintentionally coming into contact with the other of the adjacent busbars. 
     Further, a third aspect of the present invention provides a busbar assembly including a plurality of busbars each formed by a conductive flat plate member and disposed in a common plane with a gap provided between adjacent busbars, and an insulative resin layer including a gap filling part filled into the gap and a first surface-side laminate part provided on a first surface on one side in a plate thickness direction of a busbar connection body in which the plurality of busbars are connected to one another by the gap filling part, wherein the first surface-side laminate part has a plurality of first surface-side center openings that expose predetermined parts of the first surfaces of the plurality of busbars, respectively, to form a plurality of exposure regions, and wherein the insulative resin layer is formed by an insulative resin material that is nontransparent in a completely cured state. 
     The busbar assembly according to the third aspect of the present invention includes the plurality of busbars disposed in the common plane with the gap provided between the adjacent busbars, and the insulative resin layer including the gap filling part filled into the gap and the first surface-side laminate part provided on the first surface on one side in the plate thickness direction of the busbar connection body in which the plurality of busbars are connected to one another by the gap filling part, wherein the first surface-side laminate part is formed with the plurality of first surface-side center openings that expose predetermined parts of the first surfaces of the plurality of busbars, respectively, to form the plurality of exposure regions, and wherein the insulative resin layer is formed by an insulative resin material that is nontransparent in a completely cured state. 
     According to the busbar assembly, it is possible to make the edge of the first surface-side center opening on the side proximate to the gap substantially coincident with or as close as possible to the boundary of the corresponding busbar and the corresponding gap while effectively preventing or reducing generation of pinholes in the gap filling part by irradiating a laser beam to a laser area including first surface-side center opening formation areas that correspond to the plurality of first surface-side center openings and that are adjacent to each other with the gap being therebetween and an intermediate area sandwiched between the adjacent first surface-side center opening formation areas in a state that the insulative resin material provided on the entirety of the first surface of the busbar connection body is fully cured. Accordingly, it is possible to have a semiconductor element, which is mounted on the busbar assembly, arranged as close as possible to the gap while maintaining insulation property and connection strength between the adjacent busbars. 
     In any one of the busbar assemblies according to the first to third aspects, the first surface-side laminate part is configured to have a center covering area that covers the first surface of the busbar connection body at an area surrounding the plurality of first surface-side center openings in plan view, a periphery opening that exposes the first surface of the busbar connection body at an area surrounding the center covering area, and a periphery covering area that covers the first surface of the busbar connection body at an area surrounding the periphery opening in plan view. 
     Alternatively, any one of the busbar assemblies according to the first to third aspects may further include a frame that includes a cylindrical frame body with a center hole and an insulative resin layer covering an outer peripheral surface of the frame body. 
     The frame is fixed to a peripheral area of the first surface of the busbar connection body so as to surround the plurality of first surface-side center openings in plan view. 
     In any one of the above various configurations, the insulative resin layer is configured to have a second surface-side laminate part provided on a second surface on the other side in the plate thickness direction of the busbar connection body, and a side surface-side laminate part provided on a side surface of the busbar connection body and connecting the first and second surface-side laminate parts, wherein the second surface-side laminate part has a plurality of second surface-side center openings that expose predetermined parts of the second surfaces of the plurality of busbars, respectively, to form a plurality of exposure regions. 
     In a preferable embodiment, each of edges of the plurality of second surface-side center openings on a side proximate to the corresponding gap is aligned with a boundary between the corresponding busbar and the corresponding gap. 
     In a preferable embodiment, the second surface-side laminate part may further include a partition wall part extending from the gap filling part outward toward the other side in the thickness direction of the busbar connection body at an area sandwiched by the second surface-side center openings that are adjacent to each other with the gap being sandwiched therebetween. 
     Further, the present invention provides a first manufacturing method of a busbar assembly including a plurality of busbars each formed by a conductive flat plate member and disposed in a common plane with a gap provided between adjacent busbars, and an insulative resin layer including a gap filling part filled into the gap and a first surface-side laminate part provided on a first surface on one side in a plate thickness direction of a busbar connection body in which the plurality of busbars are connected to one another by the gap filling part, wherein the first surface-side laminate part has a plurality of first surface-side center openings that expose predetermined parts of the first surfaces of the plurality of busbars, respectively, to form a plurality of exposure regions, the first manufacturing method including a process of preparing a conductive metal flat plate having a busbar assembly formation area that forms the plurality of busbars, a slit formation process of forming, in the busbar assembly formation area, one or plural slit penetrating between a first surface on one side and a second surface on the other side in the thickness direction and having a width same as the gap so as to define a plurality of busbar formation parts corresponding to the plurality of busbars, a process of providing an insulative resin material in the slit and on an entirety of the first surface of the busbar assembly formation area, wherein the insulative resin material is transparent in a half-cured state and nontransparent in a completely cured state, a half-curing process of half-curing the insulative resin material, a laser beam irradiation process of irradiating a laser beam to the half-cured insulative resin material at a center laser area to form first surface-side first and second center openings, wherein the center laser area includes a first center opening formation area corresponding to the first surface-side first center opening that exposes the predetermined part of the first surface of a first busbar that is one of the busbars adjacent to each other with the gap being sandwiched therebetween, a second center opening formation area corresponding to the first surface-side second center opening that exposes the predetermined part of the first surface of a second busbar that is the other one of the busbars adjacent to each other with the gap being sandwiched therebetween, and an intermediate area sandwiched between the first and second center opening formation areas, a complete curing process of completely curing the half-cured insulative resin material, and a cutting process of cutting the busbar assembly formation area from the conductive metal flat plate. 
     Among the first manufacturing method, in a case where the first surface-side laminate part has a center covering area that covers the first surface of the busbar connection body at an area surrounding the plurality of first surface-side center openings in plan view, a periphery opening that exposes the first surface of the busbar connection body at an area surrounding the center covering area, and a periphery covering area that covers the first surface of the busbar connection body at an area surrounding the periphery opening in plan view, the laser beam irradiation process is configured to irradiate the laser beam to a periphery opening formation area that corresponds to the periphery opening to form the periphery opening, in addition to the center laser area. 
     In the first manufacturing method, the conductive metal flat plate is preferably configured to integrally have a plurality of the busbar assembly formation areas arranged in series in a first direction along a longitudinal direction of the slit, and a connection area connecting between adjacent busbar assembly formation areas. 
     In this case, the slit formed in one busbar assembly formation area is formed to have one side in the longitudinal direction extending into one connection area connected to the one side in the first direction of the one busbar assembly formation area, and another side in the longitudinal direction extending into another connection area connected to another side in the first direction of the one busbar assembly formation area. 
     Further, the present invention provides a second manufacturing method of a busbar assembly including a plurality of busbars each formed by a conductive flat plate member and disposed in a common plane with a gap provided between adjacent busbars, an insulative resin layer including a gap filling part filled into the gap and a first surface-side laminate part provided on a first surface on one side in a plate thickness direction of a busbar connection body in which the plurality of busbars are connected to one another by the gap filling part, and a frame fixed to a peripheral area of the first surface of the busbar connection body, wherein the first surface-side laminate part has a plurality of first surface-side center openings that expose predetermined parts of the first surfaces of the plurality of busbars, respectively, to form a plurality of exposure regions, wherein the frame has a cylindrical frame body having a center hole and an insulative resin layer covering an outer peripheral surface of the frame body, and is fixed to the peripheral area of the first surface of the busbar connection body so as to surround the plurality of first surface-side center openings in plan view, the second manufacturing method including a process of preparing a busbar-directed conductive metal flat plate having a busbar assembly formation area that forms the plurality of busbars; a slit formation process of forming, in the busbar assembly formation area, one or plural slit penetrating between a first surface on one side and a second surface on the other side in the thickness direction and having a width same as the gap so as to define a plurality of busbar formation parts corresponding to the plurality of busbars; a process of providing an insulative resin material in the slit and on an entirety of the first surface of the busbar assembly formation area, wherein the insulative resin material is transparent in a half-cured state and nontransparent in a completely cured state; a half-curing process of half-curing the insulative resin material; a laser beam irradiation process of irradiating a laser beam to the half-cured insulative resin material at a center laser area to form first surface-side first and second center openings, wherein the center laser area includes a first center opening formation area corresponding to the first surface-side first center opening that exposes the predetermined part of the first surface of a first busbar that is one of the busbars adjacent to each other with the gap being sandwiched therebetween, a second center opening formation area corresponding to the first surface-side second center opening that exposes the predetermined part of the first surface of a second busbar that is the other one of the busbars adjacent to each other with the gap being sandwiched therebetween, and an intermediate area sandwiched between the first and second center opening formation areas; a frame formation operation that is performed in parallel with or before or after an operation from the process of preparing the busbar-directed conductive metal flat plate until the laser beam irradiation process, wherein the frame formation operation includes a process of preparing a frame-directed conductive metal flat plate having a frame formation area that has the thickness same as that of the frame body and that has an outer peripheral shape corresponding to the busbar assembly formation area in plan view, a process of punching out a center of the frame formation area to form a frame body formation part corresponding to the frame body, and a process of providing an insulative resin material on an outer peripheral surface of the frame body formation part; an assembling process of overlapping the busbar-directed conductive metal flat plate and the frame-directed conductive metal flat plate with each other in the state in which at least one of the insulative resin material remained on the busbar-directed conductive metal flat plate after the laser beam irradiation process and the insulative resin material provided on the frame-directed conductive metal flat plate is half-cured, and then completely curing the insulative resin material in the half-cured state to have the metal flat plates fixed to each other; and a cutting process of cutting the busbar assembly formation area and the frame formation area that are overlapped with each other from the busbar-directed conductive metal flat plate and the frame-directed conductive metal flat plate after the assembling process. 
     Further, the present invention provides a third manufacturing method of a busbar assembly including a plurality of busbars each formed by a conductive flat plate member and disposed in a common plane with a gap provided between adjacent busbars, a busbar-side insulative resin layer including a gap filling part filled into the gap and a first surface-side laminate part provided on a first surface on one side in a plate thickness direction of a busbar connection body in which the plurality of busbars are connected to one another by the gap filling part, and a frame fixed to a peripheral area of the first surface of the busbar connection body, wherein the first surface-side laminate part has a plurality of first surface-side center openings that expose predetermined parts of the first surfaces of the plurality of busbars, respectively, to form a plurality of exposure regions, wherein the frame has a cylindrical frame body having a center hole and a frame-side insulative resin layer covering an outer peripheral surface of the frame body, and is fixed to the peripheral area of the first surface of the busbar connection body so as to surround the plurality of first surface-side center openings in plan view, the third manufacturing method including a process of preparing a busbar-directed conductive metal flat plate having a busbar assembly formation area that forms the plurality of busbars; a slit formation process of forming, in the busbar assembly formation area, one or plural slit penetrating between a first surface on one side and a second surface on the other side in the thickness direction and having a width same as the gap so as to define a plurality of busbar formation parts corresponding to the plurality of busbars; a process of providing an insulative resin material in the slit and on an entirety of the first surface of the busbar assembly formation area, wherein the insulative resin material is transparent in a half-cured state and nontransparent in a completely cured state; a half-curing process of half-curing the insulative resin material; a laser beam irradiation process of irradiating a laser beam to the half-cured insulative resin material at a center laser area to form first surface-side first and second center openings, wherein the center laser area includes a first center opening formation area corresponding to the first surface-side first center opening that exposes the predetermined part of the first surface of a first busbar that is one of the busbars adjacent to each other with the gap being sandwiched therebetween, a second center opening formation area corresponding to the first surface-side second center opening that exposes the predetermined part of the first surface of a second busbar that is the other one of the busbars adjacent to each other with the gap being sandwiched therebetween, and an intermediate area sandwiched between the first and second center opening formation areas; a process of completely curing the insulative resin material remained on the busbar-directed conductive metal flat plate after the laser beam irradiation process to form the busbar-side insulative resin layer; a frame formation operation that is performed in parallel with or before or after an operation from the process of preparing the busbar-directed conductive metal flat plate until the process of completely curing the insulative resin material remained on the busbar-directed conductive metal flat plate, wherein the frame formation operation includes a process of preparing a frame-directed conductive metal flat plate having a frame formation area that has the thickness same as that of the frame body and that has an outer peripheral shape corresponding to the busbar assembly formation area in plan view, a process of punching out a center of the frame formation area to form a frame body formation part corresponding to the frame body, a process of providing an insulative resin material on an outer peripheral surface of the frame body formation part, and a process of completely curing the insulative resin material provided on the frame body formation part to form the frame-side insulative resin layer; an assembling process of having the busbar-directed conductive metal flat plate and the frame-directed conductive metal flat plate fixed to each other via an adhesive so that both the conductive metal flat plates are overlapped with each other; and a cutting process of cutting the busbar assembly formation area and the frame formation area that are overlapped with each other from the busbar-directed conductive metal flat plate and the frame-directed conductive metal flat plate after the assembling process. 
     In the second and third manufacturing methods, the busbar-directed conductive metal flat plate is preferably configured to integrally have a plurality of the busbar assembly formation areas arranged in series in a first direction along a longitudinal direction of the slit, and a connection area connecting between adjacent busbar assembly formation areas, and the frame-directed conductive metal flat plate is preferably configured to integrally have a plurality of the frame formation areas arranged so as to correspond to the plurality of busbar assembly formation areas of the busbar-directed conductive metal flat plate and a connection area connecting between adjacent frame formation areas. 
     In the preferable configuration, the slit formed in one busbar assembly formation area is configured to have one side in the longitudinal direction extending into one connection area connected to the one side in the first direction of the one busbar assembly formation area, and another side in the longitudinal direction extending into another connection area connected to another side in the first direction of the one busbar assembly formation area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of a busbar assembly according to a first embodiment of the present invention. 
         FIG. 2  is a bottom view of the busbar assembly according to the first embodiment. 
         FIG. 3A  is a cross-sectional view along the line III(a)-III(a) in  FIG. 1 , and  FIG. 3B  shows an enlarged view of part III(b) in  FIG. 3A . 
         FIG. 4A  is a vertical cross-sectional view of a semiconductor module in which a semiconductor element such as an LED is mounted on the busbar assembly according to the first embodiment, and  FIG. 4B  is an enlarged view of part IV(b) in  FIG. 4A . 
         FIG. 5  is a plan view of a busbar connection body including first and second busbars that is arranged in parallel in a common plane with a gap therebetween and that are mechanically connected to each other by an insulative resin material filled into the gap,  FIG. 5  showing a state where an entirety of a first surface of the busbar connection body on one side in a thickness direction is provided with an insulative resin material. 
         FIG. 6  is a plan view of a busbar-directed conductive metal flat plate used in a method (first manufacturing method) for manufacturing the busbar assembly according to the first embodiment,  FIG. 6  showing a state after a slit formation process in the first manufacturing method. 
         FIG. 7A  is an enlarged view of the part VII(a) in  FIG. 6 , and  FIG. 7B  is a cross-sectional view along the line VII(b)-VII(b) in  FIG. 7A . 
         FIG. 8  is a plan view of the busbar-directed conductive metal flat plate provided with an insulative resin material. 
         FIG. 9A  is an enlarged view of the part IX(a) in  FIG. 8 , and  FIG. 9B  is a cross-sectional view along the line IX(b)-IX(b) in  FIG. 9A . 
         FIG. 10  is a bottom view of the part IX(a) in  FIG. 8 . 
         FIG. 11A  is a plan view of a busbar assembly formation area of the busbar-directed conductive metal flat plate, and shows a state after a complete curing process in the first manufacturing method.  FIG. 11B  is a cross-sectional view of along the line XI(b)-XI(b) in  FIG. 11A . 
         FIG. 12  is a plan view of a busbar assembly according to a second embodiment of the present invention. 
         FIG. 13A  is a cross-sectional view along the line XIII(a)-XIII(a) in  FIG. 12 , and  FIG. 13B  is a vertical cross-sectional view of a semiconductor module in which a semiconductor element is mounted on the busbar assembly according to the second embodiment. 
         FIG. 14A  is an enlarged plan view of a busbar assembly formation area in a busbar-directed conductive metal flat plate used in a method (second manufacturing method) for manufacturing the busbar assembly according to the second embodiment,  FIG. 14A  showing a state after a half-curing process in the first manufacturing method.  FIG. 14B  is a cross-sectional view along the line XIV(b)-XIV(b) in  FIG. 14A . 
         FIG. 15A  is a plan view of the busbar assembly formation area shown in  FIG. 14A ,  FIG. 15A  showing a state after a laser beam irradiation process in the second manufacturing method.  FIG. 15B  is a cross-sectional view along the line XV(b)-XV(b) in  FIG. 15A . 
         FIG. 16  is a plan view of a frame-directed conductive metal flat plate used in the second manufacturing method,  FIG. 16  showing a state after a an insulative resin material provision process in the second manufacturing method. 
         FIG. 17A  is an enlarged view of the part XVII(a) in  FIG. 16 , and  FIG. 17B  is a cross-sectional view along the line XVII(b)-XVII(b) in  FIG. 17A . 
         FIG. 18  is a plan view of the busbar-directed conductive metal flat plate and the frame-directed conductive metal flat plate after an assembling process in the second manufacturing method. 
         FIG. 19A  is a plan view of a conventional planar-type busbar assembly,  FIG. 19B  is a cross-sectional view along the line XIX(b)-XIX(b) in  FIG. 19A  and  FIG. 19C  is a vertical cross-sectional view of a semiconductor module in which a semiconductor element is mounted on the conventional busbar assembly. 
         FIGS. 20A to 20D  are process flow charts of a manufacturing method of the conventional planar-type busbar assembly, and  FIG. 20E  is an enlarged view of the part XX(e) in  FIG. 20D . 
         FIG. 21A  is a cross-sectional view showing a laser beam irradiation process in the manufacturing method of the conventional planar-type busbar assembly,  FIG. 21B  is a cross-sectional view after the laser beam irradiation process, and  FIG. 21C  is an enlarged view of the part XXI(c) in  FIG. 21B . 
     
    
    
     EMBODIMENT FOR CARRYING OUT THE INVENTION 
     First Embodiment 
     One embodiment of a busbar assembly according to the present invention will be described below with reference to the accompanying drawings. 
       FIGS. 1 and 2  show a plan view and a bottom view, respectively, of a busbar assembly  1  according to the present embodiment. 
       FIG. 3A  shows a cross-sectional view along the line III(a)-III(a) in  FIG. 1 . 
     Further,  FIG. 3B  shows an enlarged view of part III(b) in  FIG. 3A . 
     As shown in  FIGS. 1 to 3 , the busbar assembly  1  has a plurality of busbars  10  formed by a conductive flat plate member and arranged in the common plane with gaps  19  between side surfaces of adjacent busbars, and an insulative resin layer  30  fixed to the plurality of busbars  10 . 
     The busbar assembly  1  according to the present embodiment has two busbars including first and second busbars  10   a  and  10   b , as the plurality of busbars  10 . 
     As shown in  FIGS. 3A and 3B , the first and second busbars  10   a ,  10   b  have, in a vertical sectional view along the thickness direction, a first surface  11  on one side in the thickness direction, a second surface  12  on the other side in the thickness direction, opposing side surfaces  13  facing each other, and outside surfaces  14  facing directions away from each other. 
     The first and second busbars  10   a ,  10   b  are formed of conductive metal such as Cu. 
       FIG. 4A  shows a vertical cross-sectional view of an example of a semiconductor module  101  in which a semiconductor element  110  such as an LED is mounted on the busbar assembly  1 , and  FIG. 4B  shows an enlarged view of part IV(b) in  FIG. 4A . 
     In the semiconductor module  101 , one of the first and second busbars  10   a ,  10   b  acts as a positive side electrode and the other as a negative side electrode. 
     That is, the semiconductor element  110  has first and second electrode layers  111  and  112  on a lower surface on one side in the thickness direction and on an upper surface on the other side in the thickness direction, respectively, and has an element body  115  between the first and second electrode layers  111  and  112 . 
     The semiconductor element  110  has the first electrode layer  111  firmly attached in an electrically connected state to the first surface  11  of the one busbar (e.g., the first busbar  10   a ), and the second electrode layer  112  electrically connected to the first surface  11  of the other busbar (e.g., the second busbar  10   b ) via an electrical connection member  120  such as wire bonding. 
     In detail, the semiconductor element  110  is die-bonded so that the first electrode layer  111  is electrically connected to a plating layer (not shown) provided on the first surface  11  of the one busbar, and the second electrode layer  112  is electrically connected, via the wire bonding  120 , to a plating layer (not shown) provided on the first surface  11  of the other busbar. 
     A reference numeral  130  in  FIGS. 4A and 4B  denotes a sealing resin layer firmly attached to the first surface of the busbar assembly  1  so as to protect parts such as the semiconductor element  110  and the electrical connection member  120  which are mounted on the busbar assembly  1 . 
     The sealing resin layer  130  is, for example, a transparent resin such as polyimide, polyamide, epoxy, or the like. 
     In the present embodiment, the insulative resin layer  30  is formed by an insulative resin material which is a resin having heat resistance and insulative properties, and which is transparent in a half-cured state and nontransparent in a completely cured state. 
     As the insulative resin material, for example, Insuleed (registered trademark) is preferably utilized. 
     The above “transparent” means being transmissive to a laser beam (e.g., wavelength of 1064 nm) described below, and the above “nontransparent” means being absorbent to the laser beam so as to be heated and melted by irradiation of the laser beam. 
     As shown in  FIGS. 1 to 3 , the insulative resin layer  30  has a gap filling part  31  which fills the gap  19  between opposing side surfaces  13  of the first and second busbars  10   a ,  10   b  and which mechanically connects the first and second busbars  10   a ,  10   b  in an electrically insulated state, and a surface laminate part provided on an outer surface of a busbar connection body where the first and second busbars  10   a ,  10   b  are connected by the gap filling part  31 . 
     According to the busbar assembly  1  having such a configuration, since the first and second busbars  10   a ,  10   b  are arranged in the common plane, the size can be reduced as much as possible with respect to the vertical direction (thickness direction). 
     In addition, since the first and second busbars  10   a ,  10   b  are arranged so as to face each other on the opposing side surfaces  13 , the area where the first and second busbars  10   a ,  10   b  face each other can be made as small as possible compared with a laminated-type busbar assembly in which a plurality of busbars are laminated vertically; with this, a leakage current across the first and second busbars  10   a  and  10   b  can be effectively prevented or reduced. 
     In the present embodiment, the surface laminate part has a first surface-side laminate part  40  provided on the first surface on one side in the plate thickness direction of the busbar connection body, a second surface-side laminate part  50  provided on the second surface on the other side in the plate thickness direction of the busbar connection body, and a side surface-side laminate part  55  provided on the side surface of the busbar connection body and connecting the first and second surface-side laminate parts  40  and  50 . 
     As shown in  FIGS. 1 to 3 , the first surface-side laminate part  40  has first surface-side first and second center openings  41   a ,  41   b  that expose predetermined parts of the first surfaces  11  of the first and second busbars  10   a ,  10   b , respectively, at a center area of the busbar connection body in the plan view thereby to form first and second central exposure regions, and a center covering area  43  covering the first surface of the busbar connection body at an area surrounding the first surface-side first and second center openings  41   a ,  41   b.    
     Here, in the present embodiment, as shown in  FIGS. 1 and 3A , an edge of the first surface-side first center opening  41   a  on a side proximate to the gap  19  is made substantially coincident with a boundary between the first busbar  10   a  and the gap  19 . That is, the edge of the first surface-side first center opening  41   a  on the side proximate to the gap  19  and an end part of the first busbar  10   a  (inner end part) on the side proximate to the gap  19  are substantially aligned with each other. 
     Similarly, the edge of the first surface-side second center opening  41   b  on the side proximate to the gap  19  is made substantially coincident with the boundary of the second busbar  10   b  and the gap  19 . That is, the edge of the first surface-side second center opening  41   b  on the side proximate to the gap  19  and an end part (inner end part) of the second busbar  10   b  on the side proximate to the gap  19  are substantially aligned with each other. 
       FIG. 5  shows a plan view of the busbar connection body in a state where an insulative resin material  240  forming the insulative resin layer  30  is provided in the gap  19  and on the first surface on one side of the busbar connection body in the thickness direction. 
     In the case that the insulative resin material  240  is transparent in the half-cured state and nontransparent in the completely cured state, in the half-cured state of the insulative resin material  240 , irradiating a laser beam to a first surface-side center laser area  241 , which includes a first surface-side first center opening formation area  241   a  corresponding to the first surface-side first center opening  41   a , a first surface-side second center opening formation area  241   b  corresponding to the first surface-side second center opening  41   b , and a first surface-side intermediate area  241   c  sandwiched between the first surface-side first and second center opening formation areas  241   a  and  241   b , can melt, out of the first surface-side center laser area  241 , the parts in which the first and second busbars  10   a ,  10   b  are present immediately below (i.e., the first surface-side first and second center opening formation areas  241   a  and  241   b ), faster than the first surface-side intermediate area  241   c.    
     Then, after the first surface-side first surface-side first and second center opening formation areas  241   a  and  241   b  are melted and removed, the insulative resin material  240  is completely cured, making it possible to form the insulative resin layer  30 . 
     The thus configuration makes it possible to make the edge of the first surface-side first center opening  41   a  on the side proximate to the gap  19  substantially coincident with the boundary between the first busbar  10   a  and the gap  19 , and also make the edge of the first surface-side second center opening  41   b  on the side proximate to the gap  19  substantially coincident with the boundary between the second busbar  10   b  and the gap  19  while effectively preventing or reducing generation of pinholes in the gap filling part  31 . 
     Further, since it is substantially prevented or reduced to melt the gap filling part  31  where any busbar is not present directly below when the laser beam is irradiated to the first surface-side center laser area  241  in a state that the insulative resin material  240  is in the half-cured state, the first surface-side laminate part  40  is configured to have a first surface-side partition wall part  42  extending from the gap filling part  31  outward toward one side in the thickness direction of the busbar connection body at an area sandwiched by the first surface-side first and second center openings  41   a ,  41   b  in the present embodiment, as shown in  FIG. 3B . 
     The first surface-side partition wall part  42  acts as a stopper that prevents misalignment of the semiconductor element  110  when mounting the semiconductor element  110 , with an adhesive, on the first surface-side first and second central exposure regions exposed through the first surface-side first and second center openings  41   a  and  41   b.    
     Accordingly, as shown in  FIG. 4B , the semiconductor element  110  can be mounted on the corresponding exposure region (the first surface-side first central exposure region in the form shown), with the semiconductor element  110  as close as possible to the gap  19 . 
     As shown in  FIG. 1  and the like, in the present embodiment, the first surface-side laminate part  40  further has a periphery opening  45  that exposes the first surface of the busbar connection body in an area surrounding the center covering area  43 , and a first surface-side periphery covering area  47  that covers the first surface of the busbar connection body in an area surrounding the periphery opening  45 . 
     The periphery opening  45  forms a recess part (groove part) opening to the side of the first surface in cooperation with the center covering area  43  and the first surface-side periphery covering area  47 , and a step between the periphery opening  45  and the first surface-side periphery covering area  47  forms a damming structure of the sealing resin layer  130 . 
     That is, as described above, the sealing resin layer  130  (see  FIGS. 4A and 4B ) for protecting components such as the semiconductor element  110  and any necessary electrical connection member which are mounted on the busbar assembly  1  is provided by applying, onto the first surface of the busbar assembly  1 , a resin forming the sealing resin layer  130  in a manner to enclose the above components and by curing the resin. At that time, it is necessary to provide the damming structure that prevents the resin from flowing out. 
     As shown in  FIG. 4A , in the present embodiment, the recess part (groove part) formed by the center covering area  43 , the periphery opening  45 , and the first surface-side periphery covering area  47  forms the damming structure. 
     As shown in  FIG. 2  and the like, the second surface-side laminate part  50  has a second surface-side center opening  51  that exposes the second surfaces  12  of the first and second busbars  10   a  and  10   b  at the center area in the bottom view, and a second surface-side periphery covering area  53  that covers the second surface of the busbar connection body at an area surrounding the second surface-side center opening  51 . 
     In the present embodiment, the second surface-side center opening  51  has second surface-side first and second center openings  51   a  and  51   b  which expose the second surfaces of the first and second busbars  10   a  and  10   b , respectively. 
     As shown in  FIGS. 3B and 4B , the second surface-side laminate part  50  further has a second surface-side partition wall part  52  extending from the gap filling part  31  outward toward the other side in the thickness direction of the busbar connection body at an area sandwiched by the second surface-side first and second center openings  51   a ,  51   b.    
     Also by irradiating a laser beam to the second surface side of the busbar connection body in the half-cured state of the insulative resin material  240 , it is possible to make the edge of the second surface-side first center opening  51   a  on the side proximate to the gap  19  substantially coincident with the boundary between the first busbar  10   a  and the gap  19 , and also make the edge of the second surface-side second center opening  51   b  on the side proximate to the gap  19  substantially coincident with the boundary between the second busbar  10   b  and the gap  19  while effectively preventing or reducing generation of pinholes in the gap filling part  31 . 
     Next, a manufacturing method (hereinafter referred to as a first manufacturing method) of the busbar assembly  1  will be described. 
       FIG. 6  shows a plan view of a busbar-directed conductive metal flat plate  200  used in the above first manufacturing method. 
     Further,  FIG. 7A  shows an enlarged view of the part VII(a) in  FIG. 6 , and  FIG. 7B  shows a cross-sectional view along the line VII(b)-VII(b) in  FIG. 7A . 
     As shown in  FIGS. 6 and 7 , the first manufacturing method includes a process of preparing the busbar-directed conductive metal flat plate  200  having a busbar assembly formation area  210 A that is same in thickness as the first and second busbars  10   a  and  10   b , and a slit formation process of forming, in the busbar assembly formation area  210 A, slit  215  penetrating between a first surface  211  on one side in the thickness direction and a second surface  212  on the other side in the thickness direction. 
       FIG. 6  shows a state after the completion of the above slit formation process. 
     As described above, the busbar assembly  1  has two busbars, the first and second busbars  10   a  and  10   b , as the plurality of busbars  10 . Due to this, one slit  215  is formed in the above busbar assembly formation area  210 . 
     For example, for manufacturing a busbar assembly including three busbars arranged in parallel, two slits are formed. 
     As shown in  FIGS. 7A and 7B , in the present embodiment, the busbar-directed conductive metal flat plate  200  has a busbar row  205  including a plurality of the busbar assembly formation areas  210   a  arranged in series along an X direction in an X-Y plane in which the busbar-directed conductive metal flat plate  200  is located, and connection areas  230  connecting between busbar assembly formation areas  210  adjacent in the X direction, so that processing can be simultaneously performed on the plurality of busbar assembly formation areas  210 . 
     In the present embodiment, the busbar-directed conductive metal flat plate  200  has a pair of grip pieces  207  connected to one side and the other side in the longitudinal direction (X direction) of the busbar row  205 , respectively, and the pair of grip pieces  207  are provided with positioning holes  208 . 
     It is also possible to have a plurality of the busbar rows  205  arranged in parallel in the Y direction and to grip the plurality of busbar rows  205 , which are arranged in parallel in the Y direction integrally, by the pair of grip pieces  207 ,  207 . 
     According to such a modified configuration, a larger number of busbar assemblies  1  can be simultaneously manufactured. 
     In the present embodiment, the length of the busbar assembly formation area  210  in the X direction is set to be the same as the busbar assembly  1 &#39;s length in the direction parallel to the gap  19 , and the length of the busbar assembly formation area  210  in the Y direction is set to be the same as the busbar assembly  1 &#39;s length in the direction orthogonal to the gap  19 . 
     The slit  215  forms the gap  19  in the busbar assembly  1 , and has a width same as that of the gap  19 . 
     Further, the width of the gap  19  is determined according to the specification of the busbar assembly  1 . 
     In the present embodiment, the slit  215  formed in one busbar assembly formation area  210 A has one side extending into one connection area  230 ( 1 ) connected to the one side in the longitudinal direction (X-direction) of the one busbar assembly formation area  210 A, and another side extending into another connection area  230 ( 2 ) connected to another side in the longitudinal direction (X-direction) of the one busbar assembly formation area  210 A. 
     Then, in the state after the slit formation process, first and second busbar formation parts  220   a ,  220   b  facing each other via the slit  215  formed in the one busbar assembly formation area  210 A are so configured as to be maintained in a state of being connected to each other via the one connection area  230 ( 1 ) and the other connection area  230 ( 2 ). 
     Providing such a configuration can form the slit  215  (the gap  19 ) with high accuracy. 
     The first manufacturing method has a process of providing, after the slit formation process, the insulative resin material  240 , which forms the insulative resin layer  30 , in the slit  215  and on the first surface  211  on one side in the thickness direction of the busbar assembly formation area  210 . 
       FIG. 8  shows a plan view of the busbar-directed conductive metal flat plate  200  provided with the insulative resin material  240 . 
       FIG. 9A  shows an enlarged view of the part IX(a) in  FIG. 8 , and  FIG. 9B  shows a cross-sectional view along the line IX(b)-IX(b) in  FIG. 9A . 
     As shown in  FIG. 9B , in the present embodiment, the insulative resin material  240  is provided not only in the slit  215  and on the first surface  211  of the busbar assembly formation area  210 , but also on the second surface  212  and an outer peripheral surface  213  of the busbar assembly formation area  210 . 
     The insulative resin material  240  is an insulative resin, which has heat resistance and insulative properties, such as polyimide, polyamide, epoxy, and the like, and, as described above, which becomes transparent to transmit the laser beam in the half-cured state and becomes nontransparent to absorb the laser beam in the completely cured state. Preferably, Insuleed (registered trademark) is used as the insulative resin material  240 . 
     Provision of the insulative resin material  240  can be performed, for example, by electrodeposition coating of a paint containing the insulative resin material  240 . 
     Instead, it is also possible to electrostatically powder-coat the insulative resin material  240 . 
     Alternatively, in a case where the filling of the resin into the slit  215  can be sufficiently performed, it is also possible to spray the paint including the insulative resin material  240 . 
     The first manufacturing method further includes a half-curing process of half-curing the insulative resin material  240  and a laser beam irradiation process of irradiating the half-cured insulative resin material  240  with the laser beam. 
     The half-curing process is performed, for example, by heat-treating the insulative resin material  240  at a predetermined temperature and for a predetermined time. 
     The laser beam in the above laser irradiation process is of a wavelength that pass through the insulative resin material  240  in the half-cured state, for example, a wavelength of 1064 nm. 
     In the laser irradiation process, as shown in  FIG. 9A , the laser beam is irradiated to, out of the insulative resin material  240  on the first surface  211  of the busbar assembly formation area  210 A, the first surface-side center laser area  241  including the first surface-side first center opening formation area  241   a  corresponding to the first surface-side first center opening  41   a , the first surface-side second center opening formation area  241   b  corresponding to the first surface-side second center opening  41   b , and the first surface-side intermediate area  241   c  sandwiched by the first surface-side first and second center opening formation areas  241   a ,  241   b.    
     With this process, while the first surface-side intermediate area  241   c  is substantially left, only the areas in which the first and second busbar formation parts  220   a  and  220   b  are present directly below (i.e., the first surface-side first center opening formation area  241   a  and the first surface-side second center opening formation area  241   b ) are melted, forming the first surface-side first center opening  41   a  and the first surface-side second center opening  41   b.    
     In this case, the edge of the first surface-side first center opening  41   a  on the side proximate to the slit  215  (gap  19 ) is made substantially coincident with the boundary of the first busbar formation part  220   a  and the slit  215  (gap  19 ), and the edge of the first surface-side second center opening  41   b  on the side proximate to the slit  215  (gap  19 ) is made substantially coincident with the boundary of a second busbar formation part  220   b  and the slit  215  (gap  19 ); further, the first surface-side partition wall part  42  is provided (see  FIG. 3A ). 
     In the present embodiment, the laser beam irradiation process irradiates the laser beam to a periphery opening formation area  245  that corresponds to the periphery opening  45 , in addition to the first surface-side center laser area  241 . 
     Further, in the present embodiment, the laser beam irradiation process is so configured as to also irradiate the laser beam to the second surface  212  of the busbar assembly formation area  210 . 
       FIG. 10  shows a bottom view of the part IX(a) in  FIG. 8 . 
     In detail, out of the insulative resin material  240  on the second surface  212  of the busbar assembly formation area  210 , the laser beam is irradiated to a second surface-side center laser area  251  including a second surface-side first center opening equivalent area  251   a  corresponding to the second surface-side first center opening  51   a , a second surface-side second center opening equivalent area  251   b  corresponding to the second surface-side second center opening  51   b , and a second surface-side intermediate area  251   c  sandwiched by the second surface-side first and second center opening equivalent areas  251   a ,  251   b.    
     With this process, while the second surface-side intermediate area  251   c  is substantially left, only the areas in which the first and second busbar formation parts  220   a  and  220   b  are present directly below (i.e., the second surface-side first center opening equivalent area  251   a  and the second surface-side second center opening equivalent area  251   b ) are melted, forming the second surface-side first center opening  51   a  and the second surface-side second center opening  51   b.    
     In this case, the edge of the second surface-side first center opening  51   a  on the side proximate to the slit  215  (gap  19 ) is made substantially coincident with the boundary of the first busbar formation part  220   a  and the slit  215  (gap  19 ), and the edge of the second surface-side second center opening  51   b  on the side proximate to the slit  215  (gap  19 ) is made substantially coincident with the boundary of the second busbar formation part  220   b  and the slit  215  (gap  19 ). Further, the second surface-side partition wall part  52  is provided (see  FIG. 3B ). 
     The first manufacturing method further includes a complete curing process in which the insulative resin material  240 , in which a predetermined opening is provided by the laser beam irradiation process, is completely cured thereby to form the insulative resin layer  30 . 
     The complete curing process is performed, for example, by heat-treating the insulative resin material  240  in the half-cured state at a predetermined temperature and for a predetermined time. 
       FIG. 11A  shows a plan view of the busbar assembly formation area  210 A after the complete curing process, and  FIG. 11B  shows a cross-sectional view of along the line XI(b)-XI(b) in  FIG. 11A . 
     The first manufacturing method can further include a plating process in which, after the complete curing process, a plating layer (not shown) is formed in exposure regions of the pair of busbar formation parts  220   a  and  220   b.    
     The first manufacturing method further includes a cutting process in which the busbar assembly formation area  210  provided with the insulative resin layer  30  is cut from the busbar-directed conductive metal flat plate  200 , thus taking out the busbar assembly  1 . 
     As described above, in the present embodiment, the length of the busbar assembly formation area  210  in the X-direction is set to be the same as the busbar assembly  1 &#39;s length in the direction along the gap  19 , and the length of the busbar assembly formation area  210  in the Y-direction is set to be the same as the busbar assembly  1 &#39;s length in the direction orthogonal to the gap  19 . 
     On that basis, the slit  215  formed in the one busbar assembly formation area  210 A has the one side in the longitudinal direction (X-direction) extending into the one connection area  230 ( 1 ) connected to the one side in the longitudinal direction (X direction) of the one busbar assembly formation area  210 A, and another side in the longitudinal direction (X direction) extending into the other connection area  230 ( 2 ) connected to the other side in the longitudinal direction (X direction) of the one busbar assembly formation area  210 A. 
     In this case, the cutting process, as shown in  FIG. 11A , is so configured as to perform cutting at cutting lines C 1  and C 2  along edges  210 ( 1 ) and  210 ( 2 ), respectively, on one side and the other side of the busbar assembly formation area  210  in the X direction. 
     The thus configured manufacturing method makes it possible to efficiently manufacture the busbar assembly  1  according to the present embodiment. 
     That is, in the above manufacturing method, while the relative positions of the pair of busbar formation parts  220   a  and  220   b  forming the first and second busbars  10   a  and  10   b  are fixed, the slit  215  between the pair of busbar formation parts  220   a  and  220   b  is filled by the gap filling part  31 , and the first surface-side laminate part  40  is provided on the first surfaces of the pair of busbar formation parts  220   a  and  220   b , and then any unnecessary part of the first surface-side laminate part  40  is removed. 
     The pair of busbar formation parts  220   a ,  220   b , which are mechanically connected to each other by the connection area  230  in this state, are cut from the busbar-directed conductive metal flat plate  200 , thereby to manufacture the busbar assembly  1 . 
     Accordingly, it is possible to efficiently and inexpensively manufacture the busbar assembly  1  in which the first and second busbars  10   a ,  10   b  are accurately positioned at the desired relative positions, while ensuring the electrical insulation property between the first and second busbars  10   a ,  10   b.    
     Second Embodiment 
     Another embodiment of the busbar assembly according to the present invention will be described below with reference to the accompanying drawings. 
       FIG. 12  shows a plan view of a busbar assembly  2  according to the present embodiment. 
       FIG. 13A  shows a cross-sectional view along the line XIII(a)-XIII(a) in  FIG. 12 . 
     Further,  FIG. 13B  shows a vertical cross-sectional view of a semiconductor module  102  in which the semiconductor element  110  is mounted on the busbar assembly  2 . 
     In the drawings, the same reference numerals are applied to the same components as those in the embodiment 1 above, and the description thereof will be omitted as appropriate. 
     The busbar assembly  2  according to the present embodiment has a configuration different from that of the busbar assembly  1  of embodiment 1 with respect to the damming structure of the sealing resin layer  130 . 
     That is, in the busbar assembly  1  according to the above embodiment 1, the periphery opening  45  formed in the first surface-side laminate part  40  forms the damming structure. 
     On the other hand, as shown in  FIGS. 12, 13A and 13B , the busbar assembly  2  according to the present embodiment has a frame  60  that is formed separately from the busbar connection body in which the first and second busbars  10   a ,  10   b  are connected to each other and that is firmly attached to the first surface of the busbar connection body, and the frame  60  forms the above damming structure. 
     In detail, the frame  60  has a cylindrical frame body  65  having a center hole  66  penetrating in the plate thickness direction of the busbar assembly  2 , and a frame-side insulative resin layer  70  covering an outer peripheral surface of the frame body  65 . 
     The frame  60  is firmly attached to the peripheral area of the first side of the busbar connection body in a state enclosing the first surface-side first center opening  41   a  and the first surface-side second center opening  41   b  in plan view. 
     The frame body  65  can be formed, for example, by using a metal flat plate having a thickness corresponding to the thickness of the frame body  65  and by forming the center hole  66  by press working on the metal flat plate. 
     The frame-side insulative resin layer  70  is formed using an insulative resin material, such as polyimide, polyamide, epoxy, and the like. 
     The busbar assembly  2  according to the present embodiment is manufactured, for example, by the following manufacturing method (hereinafter referred to as a second manufacturing method). 
     The second manufacturing method is identical with the first manufacturing method until the half-curing process. 
     The second manufacturing method is the same as the first manufacturing method in that the laser beam irradiation process is performed after the half-curing process, but differs from the first manufacturing method with respect to the irradiation range of the laser beam. 
       FIG. 14A  shows an enlarged plan view of the one busbar assembly formation area  210 A in the state after the half-curing process in the second manufacturing method, and  FIG. 14B  shows a cross-sectional view along the line XIV(b)-XIV(b) in  FIG. 14A . 
     In the second manufacturing method, as shown in  FIG. 14A , the laser beam is irradiated to only the first surface-side center laser area  241  in the first surface-side laminate part  40 . 
       FIG. 15A  shows an enlarged plan view of the one busbar assembly formation area  210 A after the laser beam irradiation process, and  FIG. 15B  shows a cross-sectional view along the line XV(b)-XV(b) in  FIG. 15A . 
     For the second surface-side laminate part  50 , the laser beam is irradiated to the second surface-side center laser area  251  in the same manner as in the first manufacturing method. 
     The second manufacturing method is configured to perform a frame formation operation to form the frame  60  in parallel with or before or after an operation from the process of preparing the busbar-directed conductive metal flat plate  200  until the laser beam irradiation process. 
       FIG. 16  shows a plan view of a frame-directed conductive metal flat plate  300  used in the frame formation operation. 
     Further,  FIG. 17A  shows an enlarged view of the part XVII(a) in  FIG. 16 , and  FIG. 17B  shows a cross-sectional view along the line XVII(b)-XVII(b) in  FIG. 17A . 
     As shown in  FIGS. 16 and 17 , the frame formation operation includes: a process of preparing the frame-directed conductive metal flat plate  300  includes a frame formation area  310  that has the thickness same as the thickness of the frame body  65  and that has an outer peripheral shape corresponding to the busbar assembly formation area  210  in plan view, a process of punching out the center of the frame formation area  310  so that a frame body formation part  320  in the frame formation area  310  remains, and a process of providing an insulative resin material  270  on an outer peripheral surface of the frame body formation part  320 . 
       FIG. 16  shows a state after the process of providing the insulative resin material  270  on the outer peripheral surface of the frame body formation part  320 . 
     The frame-directed conductive metal flat plate  300  is configured so that, when being overlapped with the busbar-directed conductive metal flat plate  200 , the frame formation area  310  is aligned with the busbar assembly formation area  210 . 
     In detail, as described above, the busbar-directed conductive metal flat plate  200  has the busbar row  205  including the plurality of the busbar assembly formation areas  210  arranged in series along the X-direction and the connection areas  230  each connecting between busbar assembly formation areas  210  adjacent in the X-direction. 
     Accordingly, as shown in  FIG. 16 , the frame-directed conductive metal flat plate  300  having a frame row  305  that includes a plurality of the frame formation areas  310  arranged in series in the X-direction at the same pitch as the plurality of busbar assembly formation areas  210  and connection areas  330  connecting between frame formation areas  310  adjacent in the X-direction. 
     Further, as described above, the busbar-directed conductive metal flat plate  200  has the pair of grip pieces  207  connected to the one side and the other side in the longitudinal direction (X direction) of the busbar row  205 , respectively, and the pair of grip pieces  207  are provided with positioning holes  208 . 
     Accordingly, as shown in  FIG. 16 , the frame-directed conductive metal flat plate  300  is also provided with a pair of grip pieces  307  connected to the one side and the other side in the longitudinal direction (X direction) of the frame row  305 , respectively, and the pair of grip pieces  307  are provided with positioning holes  308  that correspond to the positioning holes  208 . 
     In the punching process, the center hole  66  is formed so that the frame body formation part  320  surrounds the first surface-side first center opening  41   a  and the first surface-side second center opening  41   b  when the frame formation area  310  is overlapped with the busbar assembly formation area  210 . 
     Provision of the insulative resin material  270  on the frame body formation part  320  can be performed, for example, by electrodeposition coating of a paint containing an insulative resin, which has heat resistance and insulation properties, such as polyimide, polyamide, epoxy, and the like. 
     Instead, it is also possible to electrostatically powder-coat the insulative resin material  270 . 
     Alternatively, it is also possible to spray the paint containing the insulative resin material  270 . 
     Preferably, the process of providing the insulative resin material  270  on the frame body formation part  320  can be performed simultaneously with and in the same manner as the process of providing the insulative resin material  240  on the busbar assembly formation area  210 . 
     That is, in the case of providing the insulative resin material  240  on the busbar assembly formation area  210  by electrodeposition coating, the insulative resin material  270  can be provided on the frame body formation part  320  as well by the electrodeposition coating, and in the case of providing the insulative resin material  240  on the busbar assembly formation area  210  by the electrostatic powder coating, the insulative resin material  270  can be provided on the frame body formation part  320  as well by the electrostatic powder coating. 
     According to this configuration, the manufacturing efficiency can be improved. 
     The second manufacturing method includes an assembling process that includes overlapping both the metal flat plates  200  and  300  in the state in which at least one of the insulative resin material  240  remained on the busbar-directed conductive metal flat plate  200  obtained after the laser beam irradiation process, and the insulative resin material  270  provided on the frame-directed conductive metal flat plate  300  is half-cured, then completely curing the insulative resin material in the half-cured state, and thereby firmly attaching both the metal flat plates  200  and  300 . 
       FIG. 18  shows a plan view of the busbar-directed conductive metal flat plate  200  and the frame-directed conductive metal flat plate  300  after the above assembling process. 
     Instead of overlapping both the metal flat plates  200  and  300  in the state in which at least one of the insulative resin materials  240  and  270  of the busbar-directed conductive metal flat plate  200  and the frame-directed conductive metal flat plate  300  is half-cured, it is possible to firmly attach both the metal flat plates  200  and  300  by an adhesive after completely curing the insulative resin materials  240  remained on the busbar-directed conductive metal flat plate  200  after the laser beam irradiation process and  270 , and the insulative resin material  270  provided on the frame-directed conductive metal flat plate  300 . 
     As shown in  FIG. 18 , the second manufacturing method, after the assembling process, has a cutting process in which the busbar assembly formation area  210  and the frame formation area  310  in the overlapped state are cut at the cutting lines C 1  and C 2 , and taken out from the busbar-directed conductive metal flat plate  200  and the frame-directed conductive metal flat plate  300 . 
     In each of the above embodiments, the insulative resin layer  30  provided on the busbar connection body is formed by the insulative resin material  240  that is transparent in the half-cured state and nontransparent in the completely cured state; alternatively, however, it is also possible to form the insulative resin layer  30  using an insulative resin material that is transparent in the completely cured state. 
     In this case, the laser beam irradiation process can be performed after the insulative resin material has been completely cured. 
     As a matter of course, even in the case in which the insulative resin layer  30  is formed by the insulative resin material that becomes transparent in the completely cured state, it is also possible to perform the laser beam irradiation process when the insulative resin material is in the half-cured state. 
     In each of the above embodiments, the case in which two busbars, first and second busbars  10   a  and  10   b , are arranged in parallel has been described as an example, but the present invention is not limited to such a configuration, and includes cases in which three or more busbars are arranged in parallel 
     DESCRIPTION OF THE REFERENCE NUMERALS 
     
         
           1 ,  2  busbar assembly 
           10   a ,  10   b  first and second busbars 
           19  gap 
           30  insulative resin layer 
           31  gap filling part 
           40  first surface-side laminate part 
           41   a ,  41   b  first surface-side first and second center openings 
           42  partition wall part 
           43  center covering area 
           45  periphery opening 
           47  first surface-side periphery covering area 
           50  second surface-side laminate part 
           51   a ,  51   b  second surface-side first and second center openings 
           52  second surface-side partition wall part 
           55  side surface-side laminate part 
           60  frame 
           65  frame body 
           66  center hole 
           70  frame-side insulative resin layer 
           200  busbar-directed conductive metal flat plate 
           210  busbar assembly formation area 
           215  slit 
           230  connection area 
           240  insulative resin material 
           241  first surface-side center laser area 
           241   a ,  241   b  first surface-side first and second center opening formation areas 
           241   c  first surface-side intermediate area 
           245  periphery opening formation area 
           270  insulative resin material 
           300  frame-directed conductive metal flat plate 
           310  frame formation area 
           320  frame body formation part