Abstract:
An electronic module for a vehicle includes a covering element, a component-carrier printed circuit board element, a carrier element having a first side and a second side, a printed circuit board element, and at least one contact-connection element. The contact-connection element is configured to provide a conductive contact-connection between the component-carrier printed circuit board element and the printed circuit board element. The covering element and component-carrier printed circuit board element are positioned on the first side of the carrier element, and the printed circuit board element is positioned on the second side of the carrier element. The carrier element has at least one opening, and the contact-connection element is led through the opening.

Description:
This application is a 35 U.S.C. §371 National Stage Application of PCT/EP2012/067165, filed on Sep. 4, 2012, which claims the benefit of priority to Serial No. DE 10 2011 085 918.7 and DE10 2012 213 916.8, filed on Nov. 8, 2011 and Aug. 6, 2012 in Germany, the disclosures of which are incorporated herein by reference in their entirety. 
     The present disclosure relates to electronic modules for vehicle control units. The present disclosure particularly relates to a novel design for an electronic module for a control unit of a vehicle. The present disclosure further particularly relates to an electronic module, to a control unit and also to a vehicle. 
     BACKGROUND 
     Conventional electronic modules for control units, for example known electronic modules for transmission control units, are usually designed as hermetically sealed modules. Said modules have, for example, a metal housing through which contact pins are routed to the outside. In this case, the contact pins are sealed by glass sealing. Advanced electrical connection technology to form individual functional elements in the module, for example to form sensors, internal and external plugs, is usually realized with so-called stamped grids which can be partially encapsulated in plastic, or else, for example, is designed with cable connections in the case of remote functional elements. 
     A further design of electronic modules is shown according to  FIG. 1 a   . In this case, the electronic module  1  is again designed in a hermetically sealed manner and has a covering element  4  and also a support element  7 . A component support printed circuit board element  2 , which is coupled to further printed circuit board elements  3  using contact-making elements  6 , is interposed between covering element  4  and support element  7  in a region  24  inside the covering element  4 . Said further printed circuit board elements, for their part, are arranged and designed in such a way as to provide a connection between the region  24  inside the covering element  4  and the region  26  outside the covering element  4 . 
     According to  FIG. 1 a   , the result is therefore a basic layer structure of a support element  7  and a printed circuit board element  3  which is mounted on said support element and is closed off by a covering element  4 . 
     Support element  7  can be designed, by way of example, as a metal plate, for example an aluminum plate with a sheet thickness of from 3 to 4 mm. Component support printed circuit board element  2 , by way of example in the form of a low temperature cofired ceramic (LTCC) or micro printed circuit board, is mounted on said support element, for example adhesively bonded using a thermally conductive adhesive  8 . 
     Printed circuit board element  3 , which is provided with a cutout  15 , is likewise mounted on the support element  7 , for example adhesively bonded over a wide area in an oil-tight manner using an adhesive  9 , a liquid adhesive agent or an adhesive strip. In this case, printed circuit board element  3  realizes the electrical connection between the electronic components on component support printed circuit board element  2  and the external functional elements, such as plugs, sensors etc. of the electronic module  1  for example. 
     Covering element  4  is provided and fastened on the printed circuit board element  3  by a sealing adhesive connection  10  in order to protect the electrical components of the component support printed circuit board element  2  and the contact-making elements  6 , for example bonds, against external influences such as transmission oil, metal chips and other conductive debris for example. 
     Owing to different degrees  12 ,  13 ,  14  of thermal expansion of printed circuit board element  3 , covering element  4  and adhesive connection  10 , the adhesive connection  10  is subjected to shearing stress, but this can lead to failure of the adhesive connection. As a result, it is possible for leaks to occur, in particular the hermetic sealing of the inside region  24  can fail. 
     An internal excess pressure  16  of, for example, 0.5 bar can be produced by temperature swings of, by way of example, −40° C. to +150° C. This can also subject the sealing adhesive connection  10 , in particular, to tensile loading. If the covering element  4  deforms, even slightly, further owing to the increase in pressure, the adhesive connection  10  may additionally further be subject to peeling. 
     As shown in  FIG. 1 b   , there is likewise a relatively large active pressure area  17  which additionally subjects the adhesive connection  9  between printed circuit board element  3  and support element  7  to loading by a force  18 . 
     SUMMARY 
     One aspect of the present disclosure can therefore be considered that of providing an improved electronic module design for a control unit. 
     Accordingly, an electronic module for a vehicle, a control unit for a vehicle, and also a vehicle are provided. Preferred refinements can be found in the claims. 
     According to the disclosure, the sequence of the individual elements of the electronic module, in particular the individual elements of the housing wall of the electronic module, together with the covering element, support element and printed circuit board element, is varied in such a way that a preferred refinement of the electronic module as compared with the electronic module described in  FIG. 1 a    is produced. 
     For example, the order of support element and also printed circuit board element are initially exchanged in relation to the covering element. In other words, the covering element is situated on the support element and no longer on the printed circuit board element, as illustrated in  FIG. 1 a   . The printed circuit board element is then arranged on the support element. This now results initially in a refinement of the electronic module according to the disclosure which is optimized in this respect since there is now material contact between the covering element and the support element. 
     In the case of an assumed design of covering element and support element from a similar or the same material, but at least from a material with a similar or comparable coefficient of thermal expansion, initially occurring tensile, shear or shearing forces which can act on an adhesive connection between the covering element and the support element can be reduced or avoided. 
     The printed circuit board element can then be mounted on the support element over a large area. On account of being mounted over a large area in this way, loading which occurs is less influential on account of different coefficients of thermal expansion between support element and printed circuit board element. 
     Since the printed circuit board element is further supposed to provide the function of connecting electrical components which are located in the electronic module to the outside, it is necessary to link components of the component support printed circuit board element in the region inside the covering element or in the interior of the electronic module to the printed circuit board element. To this end, a suitable opening is made in the support element, said opening allowing the printed circuit board element to make contact with the components. 
     In the context of the present disclosure, a printed circuit board element is generally to be understood to mean a signal and/or current distributing component. This therefore includes both conventionally known printed circuit boards (PCB), for example comprising an epoxy resin, and also likewise flexible circuit boards (FCB). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the disclosure are illustrated in the drawings and explained in greater detail in the following description. 
       In the drawings 
         FIG. 1 a, b    show a design of an electronic module; 
         FIG. 2 a, b    show an exemplary design of an electronic module according to the present disclosure; and 
         FIGS. 3 a  to  h    show further exemplary details of the electronic module according to the disclosure. 
         FIG. 4  Shows another exemplary design of an electronic module according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 2 a, b    show an exemplary design of an electronic module according to the present disclosure. 
     According to the disclosure, a changed layer structure of the individual components of the electronic module is indicated. Printed circuit board element  3  now bears against one side of the support element  7 , whereas covering element  4  is arranged on the opposite side of the support element  7 . By way of example, the support plate  7  used can be a metal plate, for example an aluminum sheet with a sheet thickness of 1.5 to 2 mm, possibly reinforced by beads. 
     Therefore, printed circuit board element  3  can be arranged, by way of example, on a support element bottom side  27 , whereas covering element  4  is arranged on a support element top side  28 . Printed circuit board element  3  can be mounted on the support element  7  over a wide area in an oil-tight manner using an adhesive  9 , for example a liquid adhesive agent or adhesive strip. Similarly, a component support printed circuit board element  2 , which is designed, by way of example, as an LTCC or micro printed circuit board which can be adhesively mounted on the support element using a thermally conductive adhesive agent  8 , can be arranged on the support element top side  28  in the region  24  inside the covering element  4 . As a result, a heat sink  22  can be connected to the component support printed circuit board element  2  using the support element  7 , as a result of which lost heat  11  from the electronic components which are arranged on the component support printed circuit board element  2  can be discharged to the sides via the support element  7 . Said heat sinks  22  can furthermore also be fastening points of the electronic module according to the disclosure, for example in a control unit housing. 
     Conductive elements  5 , for example copper conductors, can be introduced into the interior of the printed circuit board element  3 , said conductive elements making contact with and therefore forming a connection to the components on the component support printed circuit board element  2  with external functional elements, for example plugs or sensors, using a suitable contact-making element  6 . Similarly, a connection to a vehicle communication bus, such as a LIN or CAN bus, is feasible. 
     One to, by way of example, four opening(s)  21 , which are designed as elongate holes for example, can be provided in the support element  7  in order to realize a connection of the elements to the component support printed circuit board element  2  to conductive elements  5  which are located in the printed circuit board element  3 , for example using contact-making elements  6 , for example designed as bonds. 
     Arranging the individual elements of the electronic module in this way now makes it possible for the covering element  4  and the support element  7  to be manufactured from a comparable material, for example aluminum or steel, and therefore have an identical or at least similar or only slightly differing coefficient  12 ,  20  of thermal expansion. As a result, secure fastening of the covering element or sealing can be realized by adhesive bonding, in particular without additionally occurring shearing forces which can act on the adhesive connection. 
     In the electronic module according to the disclosure, the active pressure area  23  is considerably smaller than in conventional electronic modules owing to the structure, and this therefore results in a lower force  18 . This in turn has a positive effect on the overall design of the electronic module, in particular the adhesive connection and the leaktightness of the control unit and, respectively, of the electronic module. 
       FIG. 2 b    shows a section of the electronic module  1  through AA. 
       FIG. 3 a    shows a design of an electronic module which is comparable to that of  FIG. 2 a   . As a further detail, the support element  7  has a further opening or cutout  33 , in particular with an entry point, outside the covering element  4  and therefore in a region  26  outside the covering element  4 . In this case, the support element  7  provides access to the printed circuit board element  3  which is situated beneath it, and in particular to conductive elements  5  which are located in said printed circuit board element. Therefore, a printed circuit board element  29  can, for example, be connected to and, respectively, disconnected from the conductive elements  5 , which are located in the printed circuit board element  3 , by individual cable wires  31 . Therefore, a contact-making means for cable  29 , for example a solder pad  30 , can be arranged on the base of the opening  33 . 
     Before a possible selective soldering process, the cable or the FPC (Flexible Printed Circuit) can be fastened or held in the opening  33  by a plastic holder  32 . After the soldering process, an encapsulation compound  35  can be introduced up to a specific level  34  and, after it has cured, serves to protect against chips and/or oil for example. 
     The electronic module in  FIG. 3 b    is comparable to the electronic module  1  of  FIGS. 2 a  and 3 a   , with the exception that a sensor element  36  is provided instead of cable  29 . 
     In this case,  FIG. 3 b    shows fastening of a module functional element, by way of example a rotation speed sensor element  36 . Said element is shown, in a simplified manner, as ASIC  37  with a stamped grid and conductor tracks  38  which, at the lower end, are connected to the solder pad  30  of the printed circuit board element  3 . In order to fasten the sensor element  36 , the support element can have pins which, after the sensor element  36  is mounted, are deformed to form a rivet head  40  in order to connect sensor element  36  substantially without play. A curing encapsulation compound  39  or a coating can again be used as chip- or oil-protection means, it being possible for said chip- or oil-protection means to be subsequently introduced through opening  46 . 
       FIGS. 3 c  to 3 e    show possible connections of the covering element  4  to the support element  7 . 
     In  FIG. 3 c   , the design of elements of covering element  4  and support element  7  from substantially the same material, for example aluminum or steel, allows secure fastening of the cover and/or sealing by forming a welded connection  41 . This welded connection can be realized, by way of example, as a laser, electron beam or resistance welding connection. 
       FIG. 3 d    shows the use of an encapsulation compound  44  for sealing and fastening the covering element  4  on the support element  7 . In  FIG. 3 d   , the border  42  of the covering element  4  is introduced into a groove  43  which runs in the support element  7 , and can then be sealed and fastened with a curing encapsulation compound  44 . In this case, encapsulation compound  44  can also have a certain residual flexibility and be formed, for example, from a rubber-like material. 
       FIG. 3 e    shows a further possible connection of the covering element  4  using a rivet element  45 . To this end, a hole which passes through covering element  4 , support element  7  and printed circuit board element  3  can be used in order to insert rivet element  45 . A groove with sealing elements  48 ,  49  can be provided in support element  7  on the bottom side  27  and on the top side  28 . In this case, it is possible, for example, to dispense with an adhesive connection for sealing purposes. 
       FIG. 3 f    shows an opening, which extends into the region inside the covering element  4 , through both printed circuit board element  3  and support element  7 . The interior of the covering element can be filled, for example with a silicone gel, through this opening. Similarly, a corresponding opening can be used for a leaktightness check, for example an excess pressure check or a helium leakage test. To this end, a stepped hole  51  can be provided in the support element  7  by way of example, said stepped hole then being closed by a sealing element, for example a spherical element  52  which is introduced from the bottom side or from the side of the printed circuit board element  3  through a hole  50  which is provided in said printed circuit board, and is arrested, for example jammed, in the stepped hole  51 . 
     In  FIG. 3 g   , the support element  7  is designed, by way of example, with a U-shaped, preferably deep-drawn, region  61  which accommodates a sealing element  62 , for example a sealing ring, for sealing off the leakage path between support element  7  and printed circuit board element  3 . In this case, printed circuit board element  3  can be fastened to the support element  7  by an adhesive fastening  9 . A suitable welded connection  41  can again be used, by way of example, to fasten the covering element  4  to the support element  7 . A welding method which has a low level of heat input is particularly suitable and preferred, in order to not damage sealing ring  62  or printed circuit board  3 . 
     In the exemplary refinement according to  FIG. 3 h   , the support element  7  again has a U-shaped, deep-drawn region  61  which is provided with a sealing element  62 . In this case, the printed circuit board element  3  can be fastened in the region of the electronic module  1  by one or more pins which are formed from the same material as the support element  7  and which can be deformed, after connection, to form a rivet head  66 . 
     In this case, designing the support element  7  from a metal material for heat dissipation is limited to a region  67 , for example to the region near the electronic module. The metal design is followed, by way of example, by a molded encapsulation  68  which is formed from a plastic for example and which, as shown in region  69  by way of example, can be connected to the support element  7  by means of a peg form. 
     In this case, a molded encapsulation  68  makes it possible to combine metal and plastic in one component. In this case, complex shapes which may not have been possible to produce by deep-drawing with sheet metal can be realized in order to accommodate functional elements for example. Furthermore, resilient plastic elements and also a saving in weight in comparison to a metal structure can be realized. The molded encapsulation  68  is also known as the outsert technique. 
     The printed circuit board element  3  can be fastened, by way of example, by latching hooks  71  and/or by hot-calking pegs  72  in the plastic support element region. To this end, suitable cutouts  70  can be provided in the printed circuit board element  3 . 
     An end joint seam  65 , which is in the form of a welded connection by way of example, is used to fasten the covering element  4  to the support element  7  in  FIG. 3   h.    
     The individual details of  FIGS. 2 a  to 3 h    are not to be considered to be exclusive to the respective figure in this case. Rather, the individual elements, for example connection methods, sealing means or the like, can be freely combined in order to satisfy a required use scenario.