Abstract:
An electrical device has a housing and a housing surface, at least one electrical conductor accomodated in said housing and interrupting said housing surface in sections so that said housing surface is interrupted, a conductive body which covers said conductor on said interrupted housing surface, and at least two spacers which keep said conductive body apart from said at least one conductor.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The present invention relates to an electrical device with a housing and a housing surface, the housing surface being interrupted in sections by at least one electrical conductor accommodated in the housing.  
         [0002]     Known electrical devices of this kind are comprised of a housing into which a cooling body made of diecast aluminum is integrated. The integration is achieved by inserting the diecast cooling body into an injection mold and then partially molding the cooling body into the injection molding plastic. This partial molding produces a relatively secure, sealed connection between the cooling body and the hardened plastic housing. The housing contains other insert parts, so-called blanking skeletons, which function as conductor tracks in the housing. These conductor tracks end far enough away from an opening provided in the plastic housing that the entire opening has a closed, rectangular plastic rim. A pedestal of the cooling body protrudes into this opening and supports a substrate support or LBS. The substrate on the substrate support contacts the above-mentioned conductor tracks by means of bonding wires. In this embodiment, it is disadvantageous that the above-mentioned relatively wide plastic frame prevents a more compact design of the electrical device.  
       SUMMARY OF THE INVENTION  
       [0003]     Accordingly, it is an object of the present invention to provide an electrical device which avoids the disadvantages of the prior art.  
         [0004]     In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in an electrical device, comprising a housing and a housing surface; at least one electrical conductive accomodated in said housing and interrupting said housing surface in sections so that said housing surface is interrupted; a conductor body which covers said conductor on said interrupted housing surface; and at least two spacers which keep said conductive body apart from said at least one conductor.  
         [0005]     The electrical device according to the present invention has the advantage that providing at least two spacers between the at least one electrical conductor and another conductive body can reliably prevent short-circuiting between the conductive body and the conductor. In addition, this type of design permits further miniaturization of the electrical device.  
         [0006]     If the at least one conductor is permitted to protrude from the housing in a circumference surface of an opening and the conductive body is inserted into the opening, then on the one hand, with an intrinsically uninsulated end of the conductor, it is possible to achieve the shortest possible short-circuit-free spacings between the conductor and the conductive body. In addition, this type of design of the at least one conductor makes it possible to shorten the conductor in the opening to a required dimension.  
         [0007]     Before the conductive body is inserted into the opening, the conductors surrounding the opening can, for example, still be connected to one another by a shared middle part that is cut, for example, from the opening by means of a stamping process. The fact that the conductors are initially connected to one another by a middle part also has advantages with regard to the manufacturing process of the housing since the conductors are thus easily held in place despite the high pressures that occur during the injection molding of the housing. This improves the quality of the conductor arrangement.  
         [0008]     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. the invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a top view of the open housing in accordance with the present invention,  
         [0010]      FIG. 2  is a detailed view of the joint between the housing and the pedestal in accordance with the present invention,  
         [0011]      FIG. 3  is a detailed view of a second substrate that spans two conductors in accordance with the present invention,  
         [0012]      FIG. 4  shows a section through the above-mentioned joint in accordance with the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]      FIG. 1  is a top view of the electrical device  10 . Part of a housing  13  is shown, which has a wall  16  that delimits a housing interior  19 . The bottom of the housing interior  19  is delimited by a housing bottom surface  22 . The housing bottom surface  22  is constituted in large part by a plastic surface of the plastic housing. But sections of the housing bottom surface  22  are interrupted by one or more electrical conductors  25  accommodated in the housing  13 . The conductors  25  are so-called insert parts that are inserted into the injection mold before the housing  13  is actually injection molded and are then at least partially molded into the plastic material of the housing  13 . The surfaces of the conductors  25  are provided with so-called bond pads  28  that serve to electrically connect the conductors to a first substrate of  34  by means of so-called bonding wires  31 . In this example, these bonding wires  31  also produce an electrical contact with an optional second substrate.  
         [0014]     The housing interior  19  is provided with not only the housing opening delimited by the wall  16  but also a bottom opening  40 , which is essentially rectangular in the example and is essentially closed by a pedestal  43  of a cooling body  46 . The cooling body  46  rests against the rear of the housing  13 , not shown here, over a large area and in a tightly sealed fashion. In this exemplary embodiment, the pedestal  43  supports a substrate support  49 , which can be embodied for example as an LBS. This substrate support  49  supports the first substrate  34 . The bottom opening  40  has a circumference surface  52 , which is oriented toward the substrate support  49  in the example.  
         [0015]     As is clear from the enlarged depiction in  FIG. 2 , in the example, three conductors  25  protrude beyond the circumference surface  52  into a gap between the circumference surface  52  and the cooling body  46  and without special steps being taken, could contact the pedestal  43  or the substrate support  49  if they were positioned imprecisely. Since both the pedestal  43  and the substrate support  49  are electrically conductive because they are metallic and since they are also electrically connected, for example, to ground or to a different potential, the problem could arise that one or more adjacent conductors  25  protruding into the opening  40  would be short-circuited by means of the pedestal  43  or the substrate support  49  or would come into contact with a different, impermissible potential. Under certain circumstances, this would, for example, prevent the circuit situated on the first substrate  34  from functioning. For this reason, the conductive body, whether it is the pedestal  43  or the substrate support  49 , is kept spaced apart from the at least one conductor  25  by means of at least two spacers  55 .  
         [0016]     In the exemplary embodiment according to  FIG. 1 , a total of eight spacers  55 —two on each side of the rectangular opening  40 —prevent short-circuits between the conductors  25  and the pedestal  43  and/or substrate support  49  to which the substrate  34 , for example an electronic controller unit, is fastened. The spacers  55  in the opening  40  preferably have a height of 0.3 to 0.5 mm.  
         [0017]     The present invention thus provides an electrical device  10  having a housing  13  and a housing surface  22 ,  52 , where the housing surface  22 ,  52  is interrupted in sections by at least one electrical conductor  25  accommodated in the housing  13  and on the interrupted housing surface  22 ,  52 , the at least one conductor is covered by a conductive body  43 ,  46  and the conductive body  43 ,  46  is kept spaced apart from the conductor  25  by means of at least two spacers  55 .  
         [0018]     According to one embodiment of the present invention, the at least two spacers are integrally joined to the housing  13 .  
         [0019]     According to another embodiment of the present invention, the at least one conductor  25  protrudes from the circumference surface  52  of the opening  40  and the conductive body, whether it is the substrate support  49  or the cooling body  46  with its pedestal  43 , is in situated in the opening  40 .  
         [0020]     As has already been explained, it is immaterial to the function of the spacers  55  whether the conductive body is a pedestal  43  of a cooling body  46  or is another conductive body attached to the pedestal, for example the substrate support  49 .  
         [0021]     The conductors  25  shown in  FIG. 2  protrude into the opening  40 , among other reasons because these conductors  25  in the opening  40  are shortened to the length shown therein by means of a stamping process. The stamped edges  58  of the conductors  25  consequently protrude into the opening  40 .  
         [0022]      FIG. 3  is an enlarged top view of the second substrate  37 . As is clear from this depiction, two conductors  25  cross under the conductive body in the form of the second substrate  37 . In order to prevent the conductive body, i.e. the substrate  37 , from touching the two conductors  25  or the at least one conductor  25 , in this exemplary embodiment, a total of four spacers  55  are provided so that the substrate  37  is situated well above the conductor  25  or conductors  25 . The substrate  37  can be attached at the provided location by means of an adhesive, for example. Since the two conductors  25  shown in  FIG. 3  likewise protrude from the circumference surface  52  into the opening  40 , this side of the opening  40  must also be provided with two spacers  55  so that the pedestal  43  or the substrate support  49  cannot contact the two conductors  25  and cause a short-circuit.  
         [0023]      FIG. 4  shows a sectional view analogous to the one depicted in  FIG. 3 .  FIG. 4  shows the effect the spacers achieve by preventing the conductors  25  from contacting the pedestal  43  of the cooling body  46  or a possibly lower-slung substrate support  49 . It is also clear here how the spacers  55  protruding from the housing surface  22  support the second substrate  37  and thus reliably prevent a short-circuit or other electrical connection with at least one conductor  25  underneath the second substrate  37 . But this type of arrangement of the second substrate  37  shown in FIG.  4  also assures an insulating, virtually stress-free mechanical attachment of the second substrate  37 , for example embodied in the form of an LTCC, to the plastic housing, in particular, to the bottom housing surface  22 . A dimension of between 0.075 mm and 0.4 mm has turned out to be a suitable height for these spacers  55  situated underneath the second substrate. For example, these spacers  55  can be embodied in the form of cylinders or truncated cones, but they can also be embodied in other shapes.  
         [0024]     When there are at least two conductors  25  in the opening  40 , the spacers  55  also prevent a contact between the at least two conductors  25 . This is also true for at least two conductors  25  underneath the second substrate  37 .  
         [0025]     According to another embodiment of the present invention, the electrical device  10  is embodied as a controller of a three-phase alternator for motor vehicles.  
         [0026]     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above.  
         [0027]     While the invention has been illustrated and described as embodied in an electrical device, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.  
         [0028]     Without further analysis, the foregoing will reveal fully revela the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of the invention.