Abstract:
A cooling device has a cooling element ( 3 ) and a pressing device ( 4 ) which presses the component ( 1 ) against the cooling element ( 3 ). The pressing device ( 4 ) is resilient and is connected to the cooling element in a positive fit in order to produce fixing means which fix the component ( 1 ) to the cooling element in a reliable manner, the fixing means being easy to produce and compact.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation of co-pending International Application No. PCT/EP2004/011874, filed Oct. 20, 2004, which designates the United States, and claims priority to German application number DE 103 53 849.6 filed Nov. 18, 2003, the contents of which are hereby incorporated in their entirety by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     The invention relates to a cooling device for an electric component.  
       BACKGROUND  
       [0003]     Such a cooling device which is revealed in DE 199 42 915 A1 comprises an electric component having an insulating and thermally conductive substrate. A plurality of power semiconductor modules are arranged on the top side of the substrate and are electrically connected to conductor track structures.  
         [0004]     The underside of the substrate functions as a heat-dissipating contact area with which the substrate is pressed onto a heat sink with the aid of a pressure-exerting device in order to be able to dissipate power losses which occur in the form of heat during operation of the component. The pressure-exerting device is formed from a plurality of electrically conductive pressure pieces which are supported, on the one hand, on a covering printed circuit board and, on the other hand, on the substrate. The pressure-exerting device is of relatively complicated design and is difficult to assemble.  
         [0005]     A cooling device for an electric component having a pressure-exerting device, which is in the form of a resilient holding clip and has an anchoring region that is received by a barb of the cooling element, is also known.  
       SUMMARY  
       [0006]     A cooling device for an electric component may comprise a cooling element and a flexible pressure-exerting device which presses the component onto the cooling element in a force-locking manner.  
         [0007]     A cooling device for an electric component may also comprise a cooling element and a flexible pressure-exerting device which presses the component onto the cooling element in a force-locking manner, wherein the pressure-exerting device has a slotted sleeve which is pressed into an opening in the cooling element.  
         [0008]     A cooling device for an electric component may also comprise a means for cooling the electric component and a means for flexibly exerting pressure on the electric component to press the electric component onto the cooling element in a force-locking manner.  
         [0009]     A method of cooling an electric component may comprise the steps of providing a cooling element; arranging an electric component on the cooling element; and exerting pressure by means of a flexible device onto the cooling element in a force-locking manner to press the component onto the cooling element. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The present invention is explained in more detail below with reference to the exemplary embodiments which are shown in the figures, in which:  
         [0011]      FIG. 1  shows a cross section of an embodiment of a cooling device for an electric component,  
         [0012]      FIGS. 2   a ,  2   b ,  2   c , and  2   d  show various views of a pressure-exerting device, and  
         [0013]      FIGS. 3   a ,  3   b , and  3   c  show various views of another embodiment of a cooling device. 
     
    
     DETAILED DESCRIPTION  
       [0014]     According to an embodiment, a resilient pressure-exerting device is connected to the cooling element in a force-locking manner, thus realizing extremely simple force transmission between the component and the cooling element. In comparison with other conceivable connections, for example screw connections, the connection requires only a very small amount of space and does not require any additional fastening parts. Very simple assembly and, if desired, also disassembly are thus possible. A pressure-exerting device may preferably comprises one part.  
         [0015]     The pressure-exerting/fastening device may advantageously have one or more suitable elements for a force-locking connection, said elements being introduced, for example, into a corresponding opening in the cooling element. In this case, the connecting elements are oversized in comparison with the opening. An embodiment provides for the pressure-exerting device to have a resilient connecting element which is pressed into an opening in the cooling element. With respect to design and production engineering, the connecting element may be a slotted sleeve whose oversized dimension can be elastically and thus reversibly reduced to the width of the opening as it is being pressed into the opening. The spring force and the diameter of the sleeve make it possible to set the static friction force to such an extent that acceleration forces, as are caused, for example, by vibrations, do not result in the connection being released.  
         [0016]     In special applications, for example in the case of high-temperature and/or vibration-loading ambient conditions, it may be desirable to additionally safeguard the connection. To this end, one embodiment of a cooling device provides for the connection between the pressure-exerting device and the cooling element to be safeguarded using a lock which acts in the disassembly direction. The lock may be a barb which increases the friction forces between the participants in the connection.  
         [0017]     One embodiment which is preferred in terms of assembly provides for the pressure-exerting device to have a resilient clip which can be used to press the component onto the cooling element and which has a resilient element at both ends.  
         [0018]      FIG. 1  shows a first cooling device for an electric component (power semiconductor module)  1 . The component  1  has a heat-dissipating area  2  which is used to establish intimate thermally conductive contact between said component and a cooling element  3 . For this purpose, use is made of a pressure-exerting device  4  which is permanently connected to the cooling element  3  in a force-locking manner and exerts a contact force F 1  on the power semiconductor module  1 . The figure diagrammatically reveals an external electrical connection  5  of the power semiconductor module.  
         [0019]     The pressure-exerting device  4  is composed of a spring-elastic material, for example a leaf-spring steel, and comprises a resilient clip  8  which presses onto the power semiconductor module  1  with the contact force F 1 . In order to be fastened in a hole  9  of the cooling element  3 , the pressure-exerting device  4  has at least one force-transmitting element (connecting element)  10 . The latter is preferably formed from a cylindrical spring sleeve  11  which is formed from leaf-spring steel and has a longitudinal slot. The latter provides the force-transmitting element with the desired radial spring force. This force may be set on an application-oriented basis, by means of suitable dimensioning (length, oversized diameter, insertion depth) and diameters, in such a manner that the (static) friction forces or clamping forces F 2 , which are produced thereby, between the wall of the hole  9  and the surface of the spring sleeve  11  ensure that the latter is permanently and reliably fixed in the hole. This ensures that the counterforce to the contact force F 1  is transmitted to the cooling element  3 . For the purpose of additional safeguarding, if necessary, provision is made of a lock in the form of a barb  14  which hinders movement (in the disassembly direction D and additionally hinders rotation in the case of a cylindrical spring sleeve).  
         [0020]      FIG. 2   a  separately shows a pressure-exerting device  20  having a sleeve-shaped resilient element  21  as the fastening device, a pressure clip  22  and a barb  23 . As  FIG. 2   b  illustrates, the pressure-exerting device comprises a total of two resilient elements  21 ,  24  which are each formed as longitudinally slotted sleeves at the ends of the clip  22 . The illustration in  FIG. 2   c  and the perspective illustration in  FIG. 2   d  show that, in order to reinforce the central part  27  which adjoins the clip  22 , said central part is folded at the lower join of the sleeves  21 ,  24 . This fold  28  thus runs parallel to the clip  22 .  
         [0021]      FIGS. 3   a ,  3   b  and  3   c  show another embodiment of a cooling device, in which two parallel leaf springs  30 ,  31  which are arcuate in the unloaded state press onto a power semiconductor module  33  ( FIGS. 3   b ,  3   c ). The spring ends  30   a ,  30   b  and  31   a ,  31   b  are connected, via two crossmembers  34 ,  35 , to form a spring frame.  
         [0022]     In the respective central region of the crossmembers, provision is made of respective resilient elements  36 ,  37  which are configured, in principle, as described above and are fixed in two holes  38 ,  39  of a cooling element  40  by means of a force-locking connection ( FIGS. 3   b  and  3   c ).  
         [0023]     The cooling device is distinguished by simple assembly (and disassembly), during which, in principle, only the elements for producing the force-locking connection need to be inserted into the corresponding receptacles of the participant in the connection, which receptacles are very easy to produce by means of drilling, for example. Additional parts, for example screws, are not required and the amount of space required by this force-locking connection is very small.  
       LIST OF REFERENCE SYMBOLS  
       [0000]    
       
          D Disassembly direction  
          F 1  Contact force  
          F 2  Clamping forces  
           1  Component (power semiconductor module)  
           2  Heat-dissipating area  
           3  Cooling element  
           4  Pressure-exerting device  
           5  Connection  
           8  Clip  
           9  Hole  
           10  Force-transmitting element  
           11  Spring sleeve  
           14  Barb  
           20  Pressure-exerting device  
           21  Resilient element  
           22  Pressure clip  
           23  Barb  
           24  Resilient element  
           27  Central part  
           28  Fold  
           30 ,  31  Leaf springs  
           30   a ,  30   b  Spring ends  
           31   a ,  31   b  Spring ends  
           33  Power semiconductor module  
           34 ,  35  Crossmembers  
           36 ,  37  Resilient elements  
           38 ,  39  Holes  
           40  Cooling element