Abstract:
A power semiconductor circuit has a power semiconductor module ( 2 ) embodied as a flat assembly. A particularly compact and space-saving production of a power semiconductor circuit may be achieved with the possibilities provided by an embodiment of the power semiconductor module, whereby the power semiconductor module ( 2 ) is arranged directly on a top track ( 3 ) of a power supply and/or output tracking ( 11 ) and a cooling device ( 5 ) is integrated in the tracking ( 11 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of co-pending International Application No. PCT/EP2005/000962, filed Feb. 1, 2005 which designates the United States, and claims priority to German application number DE 10 2004 018 469.0 filed Apr. 16, 2004. 
    
    
     TECHNICAL FIELD 
     The invention lies in the field of power semiconductor technology and relates to a power semiconductor circuit. 
     BACKGROUND 
     In a conventional power semiconductor circuit which is disclosed in EP 0 901 166 A1, a power semiconductor module is constructed using conventional technology by connecting one or more individual power semiconductor elements (also referred to below as power semiconductors), for example IGBTs, to the top side of an aluminum nitride substrate via a solder layer and a metalization. The underside of the substrate is connected to a cooling device in the form of a ribbed heat sink. The module comprises a plurality of such substrates which are combined in a common housing. 
     The power semiconductor module is externally connected, by means of a screw connection, to so-called busbars which are used to pass the currents to and from the module, the busbars also being able to run at right angles through a plurality of modules. 
     A new trend in module configuration is heading in the direction of flat module geometries using lamination methods as are described, for example, in the article “A High Performance Polymer Thin Film Power Electronics Packaging Technology” by Ray Fillion et al. in Advancing Microelectronics, September/October 2003. 
     By way of example, a substrate having a component which has a contact area can thus be provided in order to produce such a module. In this case, low-inductance contact-connection is realized by bringing the contact area together with a pad which is formed on a relatively thin film. The contact area and pad are brought together by laminating the film in a vacuum press under isostatic pressure. 
     SUMMARY 
     A power semiconductor circuit may be easy to fit and may have a particularly space-saving design by comprising a power semiconductor module which is in the form of a flat subassembly and in which at least one electronic component can be arranged on a substrate and is contact-connected to a pad of a film by way of a contact area on the top side, having a busbar system which supplies and/or dissipates current and on whose one cover busbar the power semiconductor module is arranged, and having a cooling device which is integrated in the busbar system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in more detail below with reference to the exemplary embodiments which are illustrated in the figures of the drawing, in which: 
         FIG. 1  shows a side view of a power semiconductor circuit according to an embodiment, and 
         FIG. 2  shows an enlarged part from  FIG. 1  in detail. 
     
    
    
     DETAILED DESCRIPTION 
     Thus, the flat power semiconductor module my be directly integrated in the busbar system. In this case, the busbar system may be in the form of a busbar packet having a cover busbar, in which at least the area in which the module is intended to be arranged is flat. 
     The module or a plurality of flat modules may be soldered to the outside of a busbar which is in the form of a plate and is used as a positive or negative plate. This is because the positive and negative busbars are usually arranged as the topmost and bottommost plates of a plate busbar system packet. In this refinement, the modules are thus arranged on the top or bottom outer side of the busbar system. 
     Another advantageous aspect of the power semiconductor circuit according to an embodiment is that the cover busbar, to which the module is applied, can be directly cooled by a cooling device. Heat loss produced in the module can thus be dissipated in a particularly effective manner. 
     The cooling device may be in the form of an air cooling system. However, it may also be a liquid cooling system. In this case, it is advantageous if the coolant is electrically insulating. The cooling device can then be designed to be conductive and can thus carry out additional electrical functions. 
     Another preferred refinement according to an embodiment provides for the busbar system to be a busbar system packet comprising a plurality of conductors which are in the form of plates and are arranged such that they are insulated on parallel planes. A particularly compact design is thus realized. It is preferred, in terms of production, for the conductors which are in the form of plates to be connected to one another by means of lamination. Recourse can thus be had to the corresponding processes which are also used to produce the flat power semiconductor module. In this case, the lamination step or the additional lamination steps can also be effected simultaneously on the substrate. 
     The cooling device may be preferably likewise in the form of a plate and may be arranged, almost like a sandwich, between the busbars which are in the form of plates. 
     The power semiconductor module may be electrically connected to further layers or busbars of the busbar system via conductor tracks or conductor sheets which run laterally. 
     One refinement according to an embodiment which can be particularly advantageous, with respect to the contact-connection of the power semiconductor module, provides for the electronic component to be connected to the substrate by way of a contact area on the underside and for the substrate to comprise a conductive material. 
     Additional circuits, for example for control purposes, are frequently required in the immediate vicinity of the power semiconductor module. According to an embodiment, this can be realized by virtue of the control circuit being in the form of a flat unit and being arranged above the power semiconductor module. 
       FIG. 1  shows two power semiconductor modules  1  and  2  which are arranged on the top side of a topmost busbar (cover busbar)  3 . The busbar is flat and is in the form of a plate. It may be used as a positive busbar of an inverter. A cooling device  5  which may be in the form of an air cooler is situated beneath the busbar  3 . However, provision is made in this case of a liquid cooling system whose coolant  6  is electrically insulating (for example oil). The cooling device is thus insulated from a housing, for example, and can thus also undertake electrical functions. The cooling device directly cools the busbar  3  and thus ensures that the heat loss produced during operation is dissipated in a very effective manner. 
     The cooling device  5  is arranged, like a sandwich, between the cover busbar  3  and (with the interposition of insulation  7 ) a further busbar  8  which is in the form of a plate and is on a parallel plane. Provision is also made of a busbar  10  on the underside with the interposition of a further insulating layer  9 . This busbar  10  forms the negative busbar. The busbars  3 ,  8 ,  10  form, together with the cooling device  5 , a very compact arrangement which is also referred to as a busbar system packet  11 . The elements in the busbar system packet are connected to one another by means of lamination. 
     Two intermediate capacitors  12 ,  14  of an inverter, which are connected to the busbar  3  and  10  via screw connections (for example  15 ,  16  of the capacitor  12 ), are indicated under the busbar system packet. 
       FIG. 2  shows a part in the region A of  FIG. 1 . A substrate  20  which comprises a conductor, for example molybdenum, can be seen. An electronic component, for example an IGBT,  22  is soldered to the top side  21  of said substrate and a connection contact area (pad)  24  is situated on the underside  23  of said component. The substrate  20  is, for its part, soldered to the busbar  3  (cf.  FIG. 1  as well), with the result that the connection contact area  24  is directly electrically contact-connected to the busbar  3 . A plurality of electrical components can preferably be arranged on the substrate  20  in this manner, which components are intended to be at the electrical potential of the busbar  3  in accordance with the circuit specifications. 
     A film  25  of the type described initially, which has been applied by means of lamination and implements electrical connections, can be seen above the component  22 . These connections may also comprise, for example, electrical contact between a connection contact area  27  (pad), which is provided on the top side  26  of the component  22 , and a corresponding pad  28  on the film, as described in detail in German patent application having the file reference DE 103 14 172.3. The film  25  extends beyond the module  2  to the edge  29  of the busbar system packet  11  and thus also possibly reaches pads of the other busbars. The film can be processed and laminated together with the lamination of the busbar system packet  11 . 
     As indicated in  FIG. 1 , a control circuit which is in the form of a flat unit  30  on a printed circuit board is arranged above the compact unit comprising the busbar system packet  11  and the capacitors  12 ,  14 . This circuit can be connected to the elements of the power semiconductor module and/or to the busbars via wire bonds, welded joints, press contacts or soldered joints (not illustrated). 
     A very compact power semiconductor circuit, for example an inverter, which can be inserted into a relatively small housing (not illustrated) is thus realized overall. The power semiconductor circuit according to an embodiment is used to make optimum full use of the space-saving possibilities which result from the flat design of a power semiconductor module which is constructed in the form of layers. Finally, a considerable advantage in this case is also that this power semiconductor circuit can manage without the power semiconductor module and busbars being connected by means of screws. 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Power semiconductor module 
           2  Power semiconductor module 
           3  Cover busbar 
           5  Cooling device 
           6  Coolant 
           7  Insulation 
           8  Busbar 
           9  Insulating layer 
           10  Busbar 
           11  Busbar system packet 
           12  Intermediate capacitor 
           14  Intermediate capacitor 
           15  Screw connection 
           16  Screw connection 
           20  Substrate 
           21  Top side 
           22  Component 
           23  Underside 
           24  Connection contact area 
           25  Film 
           26  Top side 
           27  Connection contact area 
           28  Pad 
           29  Edge 
           30  Printed circuit board 
         A Part