Abstract:
An electrical connection configuration connects a circuit carrier to conductor tracks of a conductor-track carrier. Both the circuit carrier and the conductor-track carrier are carried by a base plate. The circuit carrier and the conductor-track carrier have a region in which they overlap and in which they are connected by an electrically conductive adhesive.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of copending International Application PCT/DE98/00770, filed Mar. 13, 1998, which designated the United States. 
    
    
     BACKGROUND OF THE INVENTION 
     FIELD OF THE INVENTION 
     The invention relates to an electrical connection configuration for connecting a circuit carrier to conductor tracks of a conductor-track carrier, and also to a method for producing an electrical connection of this type. 
     In motor vehicle electronics, in particular, it is often necessary to connect control electronics to a conductor. In motor vehicle drives, in particular, there is an increasing need to integrate control electronics in the engine or in the transmission. For this purpose, the control circuit fitted on a circuit carrier frequently has to be shielded from the oils that are used in engines and transmissions and contain additives that are extremely chemically aggressive. At the same time, however, electrical conductors have to be guided through a shield in order that components of the engine or of the transmission can be controlled electronically. 
     A connection configuration which is configured for conditions of this type is disclosed in European Patent EP 0 375 271 B1. An electronic unit disposed in a housing is connected via wires to a printed circuit board which establishes an electrical connection through a housing wall. Two different work processes are necessary for placing the electronic unit in the housing and establishing an electrical connection to the printed circuit board using wires. Establishing the electrical connection between the printed circuit board and the electronic unit is laborious in a housing. 
     U.S. Pat. No. 5,223,855 discloses a heat-generating head for a printer that has a circuit carrier and a conductor-track carrier that are electrically connected to one another. The circuit carrier and the conductor-track carrier are connected by soldering in an overlap region. Since the conductor-track carrier is disposed on the circuit carrier in the overlap region, different process steps are necessary for the fastening of the circuit carrier and the contact-making thereof with the conductor-track carrier. Published, British Patent Application GB 2 248 450 A describes an anisotropic, electrically conductive adhesive which is suitable for obtaining an electrical connection. 
     SUMMARY OF THE INVENTION 
     It is accordingly an object of the invention to provide an electrical connection of a circuit carrier to a conductor-track carrier which overcome the above-mentioned disadvantages of the prior art methods and devices of this general type, in which a simple electrical connection between a circuit carrier and conductor tracks of a conductor-track carrier are provided. 
     With the foregoing and other objects in view there is provided, in accordance with the invention, an electrical connection configuration, including a circuit carrier; a base plate having an elevation covered exclusively by the circuit carrier; a conductor-track carrier having conductor tracks disposed on the base plate; an electrically conductive adhesive disposed on the conductor-track carrier, and the circuit carrier overlapping the conductor-track carrier in an overlap region between the circuit carrier and the conductor-track carrier. In the overlap region the conductor-track carrier is disposed on the base plate and the circuit carrier is disposed on the conductor-track carrier. The circuit carrier is electrically connected to the conductor-track carrier by the electrically conductive adhesive in the overlap region, and the circuit carrier is bonded onto the conductor-track carrier exclusively in a region outside of the elevation. 
     In accordance with an added feature of the invention, there is an electrically insulating and thermally conductive adhesive bonding the circuit carrier on the base plate. 
     In accordance with another feature of the invention, the conductor-track carrier is a flexibIe sheet. 
     In accordance with an additional feature of the invention, there is a housing part disposed on the base plate and the housing part has a cavity formed therein in a region where the housing part meets the base plate. The circuit carrier is disposed in the cavity, and the conductor-track carrier is guided through between the base plate and the housing part into the cavity. 
     In accordance with a further added feature of the Invention, there is a liquid-resistant adhesive bonding the conductor-track carrier onto the base plate; and a sealing element sealing the conductor-track carrier with respect to the housing part with a result that no liquid can penetrate into the cavity. 
     With the foregoing and other objects in view there is further provided, in accordance with the invention, a method for electrically connecting a circuit carrier to conductor tracks of a conductor-track carrier, which includes providing a base plate having an elevation; fixing the conductor-track carrier adjacent to the elevation on the base plate with a result that the conductor-track carrier and the elevation form substantially one plane; disposing on a side remote from the base plate an electrically conductive adhesive on the conductor-track carrier in a region free from an insulating cover opposite a conductor track of the conductor-track carrier; and disposing the circuit carrier directly on the base plate and bonding the circuit carrier onto the conductor-track carrier in an overlap region between the circuit carrier and the conductor-track carrier with a result that an electrical connection is produced between at least one of the conductor tracks of the conductor-track carrier and a contact point of the circuit carrier and, at a same time, the circuit carrier being mechanically fixed. 
     In accordance with an added feature of the invention, there are the steps of placing a housing part having a cavity formed therein on the base plate; disposing the circuit carrier in the cavity; and guiding the conductor-track carrier between the base plate and the housing part into the cavity. 
     It is preferable for the circuit carrier to be fixed together with the control electronics simultaneously in the housing and to be electrically contact-connected to leads of the conductor-track carrier. 
     Other features which are considered as characteristic for the invention are set forth in the appended claims. 
     Although the invention is illustrated and described herein as embodied in an electrical connection of a circuit carrier to a conductor-track carrier, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, 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 
     FIG. 1 is a diagrammatic, fragmented, sectional view of a circuit carrier which is bonded onto a conductor-track carrier that has been guided through a housing wall according to the invention; 
     FIG. 2 is a sectional view through the conductor-track carrier in a direction of a bushing through the housing wall; and 
     FIG. 3 is a sectional view through the conductor-track carrier perpendicularly to the direction of the bushing. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In all the figures of the drawing, sub-features and integral parts that correspond to one another bear the same reference symbol in each case. Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown one half of a rotationally symmetrical body. A conductor-track carrier  20  is guided through a housing wall  11 . More precisely, the conductor-track carrier  20  is guided into a cavity  14  between a metallic base plate  10  and a housing part configured as a housing wall  11 . The conductor-track carrier  20  is bonded onto the base plate  10 , which is composed of aluminum, using an oil-resistant adhesive  60 . The housing wall  11  is part of a housing cover. The housing contains merely the housing cover and the base plate  10  and also an optional, peripheral, oil-resistant sealing ring  12 . The latter is pressed or vulcanized onto the conductor-track carrier  20  and seals the conductor-track  20  from the housing wall  11 . However, the housing may also contain a plurality of parts or parts that are made differently. Furthermore, the base plate  10  need not necessarily be configured in one piece. 
     In a cavity  14  produced by the housing cover, the base plate  10  has an elevation  13  relative to a plane on which the conductor-track  20  is fitted. The height of the elevation  13  corresponds to a thickness of the conductor-track carrier  20 . In this way, there is no height difference between a surface of the conductor-track carrier  20  that is remote from the base plate  10  and the elevation  13 . 
     A circuit carrier  30  with control electronics is bonded onto the conductor-track carrier  20  in an edge section using a contact adhesive  40 , and for the rest is bonded onto the elevation  13  of the base plate  10  using an electrically insulating thermally conductive adhesive  50 . The circuit carrier  30  is a ceramic substrate (LTCC) with the control electronics, conductor tracks  32  and electrical contact points  31  opposite the conductor-track carrier  20 . The contact points  31  are printed-on AgPd pads. The metallic base plate  10  serves both as a housing part and as a heat sink for the control electronics. 
     The fact that the conductor-track carrier  20  is bonded on around the elevation  13  of the base plate  10  or in a depression facilitates a mechanical fixing of the circuit carrier  30  to the base plate  10  and the simultaneous contact-making to the conductor tracks  23  of the conductor-track carrier  20 . The circuit carrier  30  is mechanically fixed to the base plate  10  by the thermally conductive adhesive  50  resulting in good heat transfer between the circuit carrier  30  and the base plate  10  serving as a heat sink. The contact points  31  of the circuit carrier  30  are contact-connected to contact pads  25  of the conductor-track carrier  20  by the electrically conductive contact adhesive  40 . 
     The same applies when the conductor-track carrier  20  is bonded onto an elevation, that is to say the circuit carrier  30  is fitted such that it is recessed relative to the conductor-track carrier  20  in accordance with its thickness. However, in this case the fixing of the circuit carrier  30  cannot be effected at the same time as the electrical contact-making. 
     Since the electrical connection between the circuit carrier  30  and the conductor-track carrier  20  are not established by bonding or soldering on wires, the space requirement on the circuit carrier  30  is minimized. 
     FIG. 2 illustrates the structure of the conductor-track carrier  20 . It shows a section through the plane II—II of FIG.  1 . The conductor-track carrier  20  is a flexible conductor-track sheet made of polyimide with a base sheet  24  and a covering sheet  21 . The conductor tracks  23  are embedded in an adhesive layer  22  between the covering sheet  21  and the base sheet  24 . A contact region with the circuit carrier  30  is free from the covering sheet  21 , with the result that the conductor tracks  23  are not covered in an electrically insulating manner there. The contact pad  25  is guided through the adhesive layer  22  and the covering sheet  21 . Over it there is applied a silver conductive adhesive as the electrically conductive contact adhesive  40 , in order to enable electrical contact-making with the contact points  31  of the circuit carrier  30 . 
     FIG. 3 shows a section view through the plane III—III of FIG.  2 . It can be seen that interspaces between individual conductor tracks  23  are likewise filled by the adhesive layer  22 .