Abstract:
An electric component connecting structure including a resin case having a first surface and a second surface, at least one metal bus bar fixed on the first surface of the resin case and having at least one welding projection portion, and at least one electric component mounted on the second surface of the resin case and having at least one lead leg. The at least one lead leg is welded to the at least one welding projection portion of the at least one metal bus bar.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an electric-component connecting structure for connecting electric components to bus bars and, more particularly, to the structure for securely fixing and connecting electric components to bus bars without the use of solder. 
     Conventionally, in order to structure an electric circuit by arranging electric components, it has been a general practice to use a substrate for connecting conductors to the electric components. Naturally, solder connection has been used in connection to the electric components. 
     However, in solder connection, there is a problem with solder-crack occurrence in the temperature impact test based on the user&#39;s specification. Meanwhile, in the recent environmental problems, there is an emphasized problem for establishing a Pb-free structure free of Pb use. 
     SUMMARY OF THE INVENTION 
     Accordingly, in order to solve such a problem, it is an object of the present invention to provide an electric-component connecting structure that is free from crack occurrence in the temperature impact test, higher in reliability than solder connection and of a Pb-free structure. 
     The outline of the present invention will be explained with FIG.  1 . In FIG. 1,  1  is a resin case,  2  to  5  are bus bars,  6  to  10  are electric components,  11  is a hole,  21  is a projection and  61  is a lead leg. 
     The object of the invention can be achieved by the following structures (1) to (3). 
     (1) The electric component connecting structure includes: a resin case  1 ; a bus bar  2  to  5  made of metal fixed on the resin case; and a welding projection  21  formed in the bus bar  2  to  5 , for connection to a lead leg  61  of an electric component  6  to  10 , wherein electric connection is made between the electric component  6  to  10  and the bus bar  2  to  5  by welding the welding projection  21  with the lead leg  61  of the electric component. 
     (2) In the electric component connecting structure of the above (1), fixing part is formed on the resin case to position or temporarily fix the electric component. 
     (3) The electric component connecting structure includes: a resin substrate; a bus bar made of metal fixed on the resin case; and a welding projection formed in the bus bar, for connection to a lead leg of an electric component, wherein electric connection is made between the electric component and the bus bar by welding the welding projection with the lead leg of the electric component. 
     This provides the below operation effects. 
     (1) By providing a bus bar  2  to  5  made of metal fixed on a resin case  1 , forming a welding projection  21  for welding to a lead leg  61  of each of a plurality of electric components  6  to  10  and welding the welding projection  21  to the electric-component lead leg  61 , electric connection is made between the electric component  6  to  10  and the bus bar  2  to  5 . Accordingly, it is possible to provide an electric component connecting structure which is free from crack occurrence in the connection even due to temperature impact test, free of Pb and higher in reliability than solder connection. 
     (2) Because the resin case is formed with fixing part to position or temporarily fix the electric component, it is possible, in advance of welding, to correctly position between the electric component and the welding projection. Thus, welding connection can be made with efficiency and correctness. 
     (3) By providing a bus bar made of metal fixed on a resin substrate, providing a plurality of welding projections for welding to lead legs of a plurality of electric components and welding the welding projection with the electric-component lead leg, electric connection is made between the electric component and the bus bar. Accordingly, it is possible to provide an electric component connecting structure which is free from crack occurrence in the connection even due to temperature impact test, free of Pb and higher in reliability than solder connection. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B show perspective explanatory views of an electric component connecting structure of the present invention; 
     FIG. 2 shows an assembly sectional view of the electric component connecting structure of the invention; 
     FIG. 3 shows an exploded perspective backside view of the electric component connecting structure of the invention; 
     FIG. 4 shows a projection-periphery magnifying view of the electric component connecting structure of the invention; 
     FIG. 5 shows a projection-periphery magnifying view, after welding, of the electric component connecting structure of the invention; and 
     FIG. 6 is a perspective view of an electric component connecting structure according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the resent invention will be explained with FIG. 1 to FIG.  5 . FIGS. 1A and 1B are a perspective explanatory view of an electric component connecting structure of the present invention. FIG. 2 is an assembly sectional view of the electric component connecting structure of the invention. FIG. 3 is an exploded perspective backside view of the electric component connecting structure of the invention. FIG. 4 is a projection-periphery magnifying view of the electric component connecting structure of the invention. FIG. 5 is a projection-periphery magnifying view, after welding, of the electric component connecting structure of the invention. 
     In the figure, the same symbols show the same parts, wherein  1  is a resin case,  2  to  5  are bus bars,  6  to  10  are electric components,  11  and  12  are holes,  13  is a partition wall,  14  is a circular definition,  15  to  18  are rectangular definitions,  21  is a projection,  22  and  23  are shoulders,  24  is a ball,  61  is a lead leg of the electric component  6 ,  8  to  10 , and  62  is a lead leg for the electric component  7 . 
     The resin case  1  is to fixedly arrange the bus bars  2 ,  3 ,  4  therein, and made, for example, of glass epoxy resin. In the back surface of the resin case  1 , partition walls  13 , a circular definition  14 , a rectangular definition  15  and the like are formed as shown in FIG.  3 . In the circular definition  14 , holes  12  greater than that for a hole  11  for the lead leg  61  of the other electric component  6 ,  8 ,  9  and  10 , are provided for the lead leg  62  of the electric component  7  like a line filter. An electric component  6  is inserted in the rectangular definition  15  while an electric component  7  is inserted in the circular definition  14 . Also, an electric component  8  is inserted in the rectangular definition  16 , an electric component  9  is inserted in the rectangular definition  17 , and an electric component  10  is inserted in the rectangular definition  18 . These definitions firmly, temporarily fix the electric components and serve to position the electric components cooperatively with the holes  11 ,  12 , thus allowing for efficient welding. 
     The bus bar  2  is provided to connect the electronic component or connect the electronic component to another circuit (not shown), and made of copper plate, brass or the like, for example. The bus bar  2  is assembled and fixed in the resin case  1  by the method of welding, adhesion, caulking, press-fitting, screwing, insert molding or the like. The bus bar  2  is also formed with a projection  21  for welding. The bus bars  3 ,  4  and  5  are similarly structured to the bus bar  2 , and assembled and fixed in the resin case  1 . 
     The electric component  6  is a component, e.g. a capacitor, to be electrically connected and fixed, by welding, to the bus bars  2  and  3 . The electric component  7  is a component, e.g. a line filter, to be electrically connected and fixed, by welding, to the bus bars  2 ,  3 ,  4  and  5 . Also, the electric components  8 ,  9  and  10  are components, e.g. capacitors, to be electrically connected and fixed, by welding, to the bus bars  4  and  5 . These electric components  6  to  10  constitute, for example, a vehicular converter. 
     Explanation will be made on the connection and assembling with the resin case  1 , the bus bars  2  to  5  and the electric components  6  to  10 . 
     (1) As shown in FIG. 1, first the bus bars  2 ,  3 ,  4  and  5  are fixed and arranged in the resin case  1 . At this time, in the resin case  1 , holes  11  and  12  are provided in the vicinity of the projections  21  formed on the bus bars  2 ,  3 ,  4  and  5 . Then, the electric component  7  is inserted in the circular definition  14  shown in FIG. 3, the electric component  6  is inserted in the rectangular definition  15 , and the electric components  8 ,  9  and  10  are respectively inserted in the rectangular definitions  16 ,  17  and  18 . Due to this, as shown in FIG. 1B the lead legs  61  and  62  of the electric components are juxtaposed to the projections  21  formed on the bus bars  2 ,  3 ,  4  and  5 , thus placed in a state ready to arc-weld. 
     (2) In this state, arc welding is made for the projections  21  and the lead legs  61 ,  62  with using an arc-welder (not shown). By this arc welding, the projected lead legs  61  and  62  and the tip of the projections  21  shown in FIG. 4 are fused into ball forms as shown in FIG. 5, then the projections  21  and the lead legs  61  and  62  are welded. Thus, the electric components are securely connected electrically and mechanically to the bus bars. 
     In the meanwhile, because the projection  21  is in a convex form having shoulders  22  and  23 , the fused balls  24  are stable in position without falling in a drop as shown as a post-welding state of FIG.  5 . Thus, such a convex form is preferred. 
     Meanwhile, because solder connection requires increased time due to remaining heat, welding with an arc-welder requiring less time is more effective. 
     Because the resin case is formed with definitions by partition walls or the like and the components can be firmly inserted and temporarily fixed therein, welding operation can be effectively carried out. 
     Moreover, because the holes are formed in the vicinity of the projections, the electric components can be correctly positioned. Thus, welding operation can be effectively carried out. 
     In this manner, it is possible to provide an electric component connecting structure which is free from crack occurrence even in the temperature impact test and does not use Pb. 
     Although the foregoing explanation explained the example using a resin case on which bus bars are provided, the invention is not limited to this, i.e. a resin substrate  1 ′ may be used as shown in FIG.  6 . In that case, although the positioning of electric components  6 ,  7 ,  8 ,  9 ,  10  is only with the holes  11 ′,  12 ′, positioning is correctly made which also makes welding operation effective. 
     The present invention can provides the following effects. 
     (1) Metal-make bus bars  2  to  5  are provided fixed on a resin case  1 , welding projections  21  for welding to the lead legs  61  of a plurality of electric components  6  to  10  are formed in the bus bars  2  to  5  and the welding projections  21  are welded to the electric-component lead legs  61  thereby electrically connecting the electric components  6  to  10  to the bus bars  2  to  5 , whereby it is possible to provide an electric component connecting structure that is free from crack occurrence even due to a temperature impact test, Pb-free and higher in reliability than solder. 
     (2) Because fixing part for positioning or temporarily fix the electric components is formed in the resin case, it is possible, in advance of welding, to correctly position between the electric components and the welding projections and carry out soldering and connection efficiently and correctly. 
     (3) Metal-make bus bars are provided fixed to a resin substrate, welding projections for welding to the lead legs of a plurality of electric components are formed in the bus bars and welding is made to the lead legs of electric components through the welding projections, whereby it is possible to provide an electric component connecting structure that is free from crack occurrence even due to a temperature impact test, Pb-free and higher in reliability than connection by soldering.