Abstract:
A control device includes a number of individual flexible printed circuit boards that are preferably laminated on an aluminum base plate. A molded seal is used to reliably seal the edge areas of the partially flexible printed circuit board and these edge areas are formed to assist in creating the seal. The device is suited for mechatronic control units and is particularly suited for control devices that are mounted in a transmission or engine of a motor vehicle.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a control apparatus, in particular for mechatronic control devices associated with the transmission control or engine control of a motor vehicle. The apparatus includes:
         a circuit carrier which is connected to conductor paths of at least one flexible conductor path carrier, and   a base plate on which the circuit carrier and the conductor path carrier are mounted, and   a housing part which forms a cavity in which the circuit carrier is arranged, wherein
           the conductor path carrier is guided between the base plate and the housing part into the cavity, and wherein   the conductor path carrier is adhered at least partly to the base plate by means of a liquid-resistant adhesive and sealed relative to the housing part by means of at least one gasket element, such that no liquid can penetrate into the cavity.   
               

     It is increasingly the case that automatic transmissions for private motor vehicles are largely electronically controlled, and this also applies to combustion engines or braking systems, etc. Whereas so-called “standalone” control devices for this purpose were previously provided for installation in an electronics space (e-box) offering protection against environmental influences or in the passenger compartment, there is a growing trend towards so-called mechatronic control units, i.e. the integration of control electronics and the associated sensor technology in the transmission, the engine, the braking system or similar. There are similar trends towards localized electronic systems in other fields outside of motor vehicle engineering, e.g. air travel and space travel engineering, ship engineering, etc. 
     In some applications of mechatronic control units, pressed screens are used for current and signal distribution. In comparison with so-called flexible technology, however, this solution exhibits clear disadvantages in respect of issues such as sealing the electronics space, stress protection, flexibility and tolerance equalization. Furthermore, as a result of complying with minimal cross sections of the pressed screens, routing of the conductor paths is more difficult than in the case of flexible conductor paths (construction of extremely fine Cu conductor path structures). In addition, modifications require costly intervention in the pressing tool. 
     As illustrated in  FIGS. 1 to 5 , current production applications for e.g. a mechatronic transmission control unit comprise a circuit carrier  30  which is connected to conductor paths  23  of at least one flexible conductor path carrier  20  for the distribution of electrical signals and currents. The circuit carrier  30  and the conductor path carrier  20  are mounted on a base plate  10 . The circuit carrier  30  is arranged in a cavity  14  which is formed by a housing part  11 , wherein the conductor path carrier  20  is guided between the base plate  10  and the housing part  11  into the cavity  14  and adhered at least partly to the base plate  10  by means of a liquid-resistant adhesive  22  and sealed relative to the housing part  11  by means of at least one gasket element  12 , such that no liquid can penetrate into the cavity  14 . 
     In a perspective illustration,  FIG. 1  shows the basic structure of the sealing concept for the electronics space  14  of a transmission control device;  FIG. 2  shows the structure as per  FIG. 1  in a side view. 
       FIG. 3  shows the extract X from  FIG. 2  in a magnified illustration. The illustrated layer structure of a flexible conductor path carrier  20  usually consists of a first base film  24  and a second cover film  21 , each of these being made of e.g. polyamide, wherein conductor paths  23  of e.g. copper (Cu) are embedded between said films. A solid unit is produced by using an acrylic adhesive  22  between the layers  21  and  24 . 
       FIG. 4  shows the flexible layout of a mechatronic transmission control unit;  FIG. 5  shows the basic structure of a mechatronic control unit when using an integral, single-layer flexible circuit board  20 . 
     The above described sealing concept is disclosed in e.g. U.S. Pat. No. 6,300,566 B1 or EP 0 972 318 B1, wherein single-layer oil-resistant flexible circuit boards  20  are used without exception for the distribution of current and signals for reasons of cost. This special flexible material  20  is currently always embodied as an integral component, i.e. the film  20  completely surrounds the circuit carrier  30 , which means the use of large areas of expensive flexible material  20 . Moreover, a rectangular area  29  which cannot be used must be left open for the electronics  30  in the central area of the film  20 . In order to reach all connector areas  33 ,  34  at the same time as optimally exploiting the possible uses, a specially developed folding technique is utilized. It is nonetheless unavoidable that rejects frequently occur, since the transmission installation spaces do not allow otherwise. 
     SUMMARY OF THE INVENTION 
     With this as its starting point, the present invention addresses the problem of specifying measures which firstly allow a considerable reduction in the area of the expensive flexible material, particularly in mechatronic control apparatuses. Furthermore, measures will be specified for ensuring comparable impermeability. 
     According to the invention, this problem is solved by the features in the independent patent claim. Advantageous embodiments and developments, which can be used singly or in combination with each other, are the subject matter of the dependent claims. 
     The invention develops control apparatuses of the type in question, in that provision is made for at least one partial flexible circuit board which at the most partially i.e. not completely surrounds the circuit carrier as a conductor path carrier, wherein preferably two to n (in particular four) partial flexible circuit boards are provided. 
     In order that the pressed edges of the partial flexible circuit board can also be sealed using gaskets similar to the well-tested sealing concept described in the introduction over the service life of a control apparatus, various advantageous embodiments and developments are specified below. 
     In a first embodiment, it is thus proposed that in the boundary area of the partial flexible circuit board(s) a smooth slope is formed, preferably as far as the level of the base plate, such that the remaining transition zone can be permanently sealed using a gasket element. The formation of the perimeter slope can be achieved, for example, by means of a shaping tool which permanently shapes the boundary area at least in places, wherein the resulting transition zone can advantageously be permanently sealed by means of the sealing element. 
     Alternatively or in addition to this, it is proposed that (e.g. epoxy-based) adhesive dots be placed in the boundary areas of the partial flexible circuit board(s), wherein the gasket element is positioned on said dots and forms a seal thus. 
     In a further embodiment, it is proposed that an adhesive track be deposited in areas between the partial flexible circuit board(s), forming an elevation which is identical to that of the partial flexible circuit board(s). This advantageously ensures that the gasket element lies on a plane again. The gasket element then lies level on the partial flexible circuit board(s) and in the transition zones on the adhesive track(s). This ensures that the gasket element lies on a plane again. The pressed boundary areas of the partial flexible circuit board(s) are sealed by means of the adhesive track. Use of a screen printing method is well proven for applying the adhesive tracks, such that any imperfections at the pressed boundary areas can be advantageously evened out immediately. 
     In a further embodiment, it is proposed that an adhesive bead is applied circumferentially, wherein the gasket element is positioned on said adhesive bead. In this case, the (e.g. epoxy) adhesive bead advantageously seals all interfaces to the partial flexible circuit board(s), the base plate and the housing simultaneously. 
     In a further embodiment, it is proposed that in the areas where the partial flexible circuit board(s) rest on the base plate, a smooth transition zone be formed in the base plate. This advantageously produces an identical elevation of base plate and top side of the partial flexible circuit board(s). 
     According to the invention, after adhesion of the partial flexible circuit board(s) by means of a liquid-resistant adhesive on the base plate, a circumferential and continuous gasket profile is preferably deposited on the components, e.g. by means of a spraying method, advantageously thereby securely closing all unevennesses and possible openings between the partial flexible circuit board(s) and the base plate or floor plate. The housing part together with the gasket element can be located on the continuous gasket profile by means of an adhesive connection. Alternatively or in addition to this, the housing part together with the gasket element can be located and mechanically secured onto the continuous gasket profile, e.g. by means of rivets. An exclusively mechanical securing advantageously allows non-destructive opening for any repairs or recycling activities subsequently. 
     It is appropriate suitably to support the course of the gasket element in respect of the sealing properties by means of structural measures in the housing part and/or the base plate. The concept can also be advantageously supported by a special embodiment of the gasket element. 
     In particular, in a further embodiment of the development, it is proposed to configure the cover film below the gasket element such that it is set back in relation to the base film in the boundary area of the partial flexible circuit board(s), thereby reducing the height of the step at the flexible pressed edge. 
     The present invention has the advantage of significant cost savings due to a reduction in the flexible material (by a factor of 2 to 3). Moreover, it allows previously unknown structural freedom in the layout of the device design, e.g. a variable arrangement of the flexible parts, a simplified implementation of intersections by means of superimpositions of two flexible parts and/or possibly minimizing the number of rivets, even to the extent that these are omitted altogether. In addition, the present invention allows an effective combination of pressed screen technology and flexible technology, particularly in the field of valve contacting using connection paths to the electronics space, and in the use of the well-tested Siemens VDO laser welding method for flexible to pressed screen, or in the use of a flexible film in the sealing region and in the region of the plug connector and the sensors, if applicable, in order to achieve optimal tolerance equalization. Lastly, the present invention provides cost savings in manufacturing and assembly, particularly in respect of the folding processes, as well as increased quality in the use of a small number of well-tested connection technologies such as bonding, laser welding, etc., a reduction in purchase prices of flexible materials as a result of using a plurality of possible suppliers thereof (reduced complexity and tolerance requirements) and finally, as a result of switching from a single complex flexible complete part to a combination of a plurality of simple flexible individual parts, it advantageously shortens the development times of mechatronic control devices, particularly those installed in the transmission or engine of a motor vehicle. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
       Additional details and further advantages of the invention are described below with reference to a preferred exemplary embodiment in connection with the appended drawing, in which: 
         FIG. 1  schematically shows a perspective illustration of the basic structure of the sealing concept of the electronic space of a transmission control device; 
         FIG. 2  schematically shows the structure as per  FIG. 1  in a side view; 
         FIG. 3  schematically shows the extract X from  FIG. 2  in a magnified illustration of the side view; 
         FIG. 4  schematically shows the flexible layout of a mechatronic transmission control unit; 
         FIG. 5  schematically shows the basic structure of a mechatronic control unit when using a single-part, single-layer flexible circuit board; 
         FIG. 6  schematically shows the basic structure of a mechatronic control unit when using a plurality of single-layer partial flexible circuit boards according to the invention; 
         FIG. 7  schematically shows the exemplary embodiment as per  FIG. 6  including shaped flexible boundary areas; 
         FIG. 8  schematically shows the shaped flexible boundary areas from  FIG. 7  in a side view; 
         FIG. 9  schematically shows the exemplary embodiment as per  FIG. 6  including flexible boundary areas which have been adhered by means of adhesive dots; 
         FIG. 10  schematically shows the exemplary embodiment as per  FIG. 6  including flexible boundary areas which have been adhered by means of equalizing adhesive tracks; 
         FIG. 11  schematically shows the flexible boundary areas which have been adhered by means of equalizing adhesive tracks as per  FIG. 10  in a side view; 
         FIG. 12  schematically shows the exemplary embodiment as per  FIG. 6  including flexible boundary areas which have been adhered by means of an adhesive bead; 
         FIG. 13  schematically shows the exemplary embodiment as per  FIG. 6  including shaped aluminum base plate; 
         FIG. 14  schematically shows the shaped aluminum base plate from  FIG. 13  in a side view; 
         FIG. 15  schematically shows the exemplary embodiment as per  FIG. 6  including pointed gasket. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following description of the preferred embodiments of the present invention, identical reference signs designate identical or comparable components. 
       FIG. 1  shows the basic structure of the sealing concept of the electronic space of a transmission control device in a perspective illustration. 
       FIG. 2  shows the structure as per  FIG. 1  in a side view. 
     The half of a reflectively or rotationally symmetrical body is shown. A conductor path carrier  20  is guided through a housing wall  11 . More precisely, the conductor path carrier  20  is guided between a metallic base plate  10  and a housing part which is formed as a housing wall  11  into a cavity  14 . The conductor path carrier  20  is adhered onto the base plate  10 , which preferably consists of aluminum, using an oil-resistant acrylic adhesive  22 . The housing wall  11  is part of a housing cover which is preferably a plastic molded part. The housing  11  consists solely of the housing cover and the base plate  10 , and includes a circumferential oil-resistant sealing ring  12  of fluorosilicone, for example. This  12  is pressed or vulcanized onto the conductor path carrier  20  and seals the conductor path carrier  20  relative to the housing wall  11 . In addition to adhesive connections, mechanical securing is also possible in this context, e.g. by means of rivets  18  (only shown in  FIG. 1 ). However, the housing can also consist of a plurality of parts or parts of a different nature (not illustrated). Moreover, the base plate  10  does not have to be a unitary part. 
       FIG. 3  shows the extract X from  FIG. 2  in a magnified illustration. The illustrated layer structure of a flexible conductor path carrier  20  consists of a first base film  24  and a second cover film  21 , each of these being made of e.g. polyamide, wherein conductor paths  23  of e.g. copper (Cu) are embedded between said films. A solid unit is produced by using an acrylic adhesive  22  between the layers  21  and  24 . The same type of acrylic adhesive  22   a  can also be used for adhering or laminating the base layer  24  onto the base plate or underlying plate  10 . Also clearly visible is the manner in which the gasket element  12 , more concisely designated below as gasket  12 , adapts to the contours of the cover film  21 . 
       FIG. 4  shows the flexible layout of a mechatronic transmission control unit. Visible are e.g. individual lines  23  which disperse in a star format from sensors or actuators  33  and/or plug connectors  34  for connecting e.g. to the cable harness of a motor vehicle (not shown) to the control electronics  30  and electronic components  32  which are arranged thereupon. It is clear that provision is made for an opening in the center of the flexible layout, and the circuit carrier  30  including the control electronics circuit  32  is positioned in said opening. 
       FIG. 5  shows the basic structure of a mechatronic control unit when using a single-part, single-layer flexible circuit board  20  in an interior view in detail. It is possible to see the control electronics  30  which are arranged in an opening  29  in the interior area of the flexible circuit board  20 . The ends of the Cu paths  23  in the flexible circuit board  20  are connected to the electronics  30  via electrical contact points  31  by means of bonding connections  40 . The position of the circumferential gasket  12  is also indicated in this view. 
     Instead of a bonding connection  40 , provision can also be made for the electrical connection arrangement described in U.S. Pat. No. 6,300,566 B1 or EP 0 972 318 B1, full reference to whose disclosure in this respect is made hereby. 
       FIG. 6  shows the basic structure of a mechatronic control unit when using a plurality of preferably single-layer partial flexible circuit boards according to the invention. In order to make the boundary areas  25  of the partial flexible circuit boards  20   a ,  20   b  accessible in the area of the sealing cushion  12  of a seal through this  12 , the following suitable measures are specified: 
       FIG. 7  shows the exemplary embodiment as per  FIG. 6  with so-called shaped flexible boundary areas  25 . These  25  were permanently shaped by means of a shaping tool (not illustrated) such that a smooth slope down to the aluminum level of the base plate  10  is produced in the flexible boundary area  25 . The level equalization which is thus formed to the underlying plate  20  advantageously allows a permanent seal by means of the gasket  12 . 
       FIG. 8  shows the boundary areas  25  of the partial flexible parts  20   a ,  20   b , . . . from  FIG. 7  in a side view, said boundary areas  25  being shaped in the sealing area, thereby advantageously allowing a positive placement of the inlay seal  12  onto the shaped edge  25 . 
       FIG. 9  shows the exemplary embodiment as per  FIG. 6  including flexible boundary areas  25  which have been adhered by means of e.g. epoxy-based adhesive dots  26 . The gasket  12  is then deposited. 
       FIG. 10  shows the exemplary embodiment as per  FIG. 6  including flexible boundary areas  25  which have been adhered by means of equalizing adhesive tracks  27 . One or more adhesive track(s) are deposited in the curve or straight section between the two flexible parts  20   a ,  20   b  until the same elevation as the flexible parts  20   a ,  20   b , . . . is reached. The gasket  12  then lies level on the flexible parts  20   a ,  20   b , . . . and in the transition zones on the adhesive tracks  27 . This ensures that the gasket  12  lies on a plane again. The flexible pressed edges  25  are sealed by means of the adhesive  27 . 
       FIG. 11  shows the flexible boundary areas  25  from  FIG. 10  which have been adhered by means of equalizing adhesive tracks  27  in a side view. It is shown how, in accordance with the invention, the adhesive layer  27  is preferably applied by means of a screen printing method. In this case, an adhesive  27  is deposited onto the partial flexible circuit boards  20   a ,  20   b , . . . and the floor plate  10  by means of a screen printing squeegee through a screen such that only defined columns or partial flexible areas are filled by the adhesive  27 . An arrow indicates the direction of travel of the squeegee  50 . Adhesive tracks  27  which are deposited by means of a screen printing method advantageously even out any imperfections at the flexible edges  25  at the same time. 
       FIG. 12  shows the exemplary embodiment as per  FIG. 6  including flexible boundary areas  25  which have been adhered by means of an adhesive bead  28 . It can be seen how an adhesive bead  28  is deposited circumferentially and the cover  11  is adhered to the base plate  10 . In this case, the adhesive (e.g. epoxy) simultaneously seals all interfaces to the flexible parts  20   a ,  20   b , . . . , to the aluminum plate  10  and to the plastic cover  11 . An acrylic adhesive film  22  which is sensitive to pressure and temperature can also be used as an adhesive, said film alone adhering the flexible parts  20   a ,  20   b , . . . to the floor plate  10  in an oil-resistant manner. In this embodiment, it is possible to dispense with a mechanical fastening measure (e.g. rivets  18 ) if applicable. 
       FIG. 13  shows the exemplary embodiment as per  FIG. 6  including an aluminum base plate  10  which is shaped in the areas where the flexible parts  20   a ,  20   b , . . . are situated. In this way, the same elevation is obtained for the floor plate  10  and top sides of the partial flexible circuit boards  20   a ,  20   b , . . . . The contour width of the floor plate  10  is advantageously somewhat larger than the width of the partial flexible circuit board  20   a ,  20   b , . . . . The resulting “hole” between flexible part edge  25  and contour depth  16  on the floor plate  10  can be filled e.g. by means of surplus adhesive  22  during the flexible part laminating process or equalized by means of additionally placed adhesive dots  26 . Residual unevennesses on the resulting surface which must be sealed relative to the cover  11  are significantly smaller than the original flexible part thickness and can be sealed reliably by means of the gasket  12 . 
       FIG. 14  shows the shaped aluminum base plate  10  from FIG.  13  in a side view. 
       FIG. 15  lastly shows the exemplary embodiment as per  FIG. 6  including pointed gasket  12 . Following the lamination of the flexible part sections  20   a ,  20   b , . . . onto the floor plate  10 , a circumferential and continuous gasket profile  17  is deposited on the floor plate  10  and the flexible part modules  20   a ,  20   b , . . . , in particular by means of spraying. In this way, any unevennesses and possible openings between partial flexible circuit boards  20   a ,  20   b , . . . and the floor plate  10  are securely closed. The sealing cover  11  is placed onto said gasket profile  17  which is now sprayed on, and e.g. mechanically secured to the floor plate using a corresponding sealing force, e.g. by means of rivets. 
     The present invention advantageously and for the first time permits the arrangement of a plurality of individual partial flexible circuit boards  20   a ,  20   b , . . . in such a way as to allow the optimal routing of signal and current paths while at the same time reducing to a minimum the use of expensive flexible surfaces  20 . It therefore assists in economizing flexible surfaces  20  and in the configuration of flexible component parts such that uses can be optimally exploited and therefore no rejects occur. The individual partial flexible circuit boards  20   a ,  20   b , . . . are preferably laminated onto a base plate  10  of aluminum. The boundary areas  25  of the partial flexible circuit boards  20   a ,  20   b , . . . are formed using suitable measures such that a secure seal is ensured by means of a gasket. 
     The present invention is therefore suitable for mechatronic control units, in particular for control devices for installation in a transmission or engine of a motor vehicle.