Electrical or electronic control device

Electrical or electronic control device has an electrical or electronic assembly, which includes a printed circuit board composed of an electrically insulating carrier material, electrically conductive conductor tracks formed on the printed circuit board, and electrical or electronic modules connected to the printed circuit board and via the conductor tracks. A coating is applied at least in sections to the electrical or electronic assembly. The coating includes at least the following layers: a first electrical conductor layer, a second electrical conductor layer, a dielectric layer arranged between the first conductor layer and the second conductor layer, an insulator layer applied to the second conductor layer in such a way that the second conductor layer is arranged between the dielectric layer and the insulator layer. An evaluation unit is connected to the conductor layers and detects a change in capacitance of the coating.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. 10 2020 125 942.5, filed Oct. 5, 2020, the content of such application being incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The invention relates to an electrical or electronic control device.

BACKGROUND OF THE INVENTION

Electrical or electronic control devices known from practice have an electrical or electronic assembly, which comprises a printed circuit board composed of an electrically insulating carrier material having electrically conductive conductor tracks formed on the printed circuit board and electrical or electronic modules connected to the printed circuit board and via the conductor tracks. Such an electrical or electronic assembly having the printed circuit board, the electrically conductive conductor tracks and the electrical or electronic modules is also referred to as a populated printed circuit board. During operation, an electrical or electronic control device of this kind is subjected to heating as a result of the resistance of the electrically conductive conductor tracks and the electrical or electronic modules and also as a result of the current that flows. An impermissibly high degree of heating can lead to a malfunction of or even damage to the electrical or electronic control device. Until now, it has been difficult to easily and reliably detect such heating of an electrical or electronic control device.

DE 10 2014 006 841 A1, which is incorporated by reference herein, discloses a circuit arrangement of a motor vehicle. The circuit arrangement has a metallic carrier plate, a metallic printed circuit board and semiconductor modules. The metallic carrier plate is spaced apart from the metallic printed circuit board in an electrically insulated manner. The carrier plate and the printed circuit board are electrically connected by means of a semiconductor module and form an electrical three-pole.

DE 39 37 183 A1, which is incorporated by reference herein, discloses a printed circuit board arrangement having a printed circuit board composed of an insulating carrier material. Conductor tracks are formed on the front side and the rear side of the printed circuit board. The printed circuit board is embodied as a multi-layer printed circuit board in such a way that layer levels thereof form an interference-suppression capacitor.

US 2019/0 217 781 A1, which is incorporated by reference herein, discloses an electrical or electronic control device of a vehicle.

US 2017/0 215 271 A1, which is incorporated by reference herein, and EP 3 461 241 A1, which is incorporated by reference herein, disclose further prior art.

SUMMARY OF THE INVENTION

An electrical or electronic control device has an electrical or electronic assembly, which comprises a printed circuit board composed of an electrically insulating carrier material, electrically conductive conductor tracks formed on the printed circuit board and electrical or electronic modules connected to the printed circuit board and via the conductor tracks.

The electrical or electronic control device furthermore has a coating applied at least in sections to the electrical or electronic assembly, wherein the coating comprises at least the following layers: a first electrical conductor layer, a second electrical conductor layer, a dielectric layer arranged between the first conductor layer and the second conductor layer, and an insulator layer applied to the second conductor layer in such a way that the second conductor layer is arranged between the dielectric layer and the insulator layer.

The electrical or electronic control device furthermore has an evaluation unit, which is connected to the conductor layers and which detects a change in capacitance of the coating, caused by a change in temperature of the electrical or electronic assembly, based on measurement variables tapped at the conductor layers of the coating.

The evaluation unit is preferably contact-connected to the first electrical conductor layer of the coating and the second electrical conductor layer of the coating by means of a respective measurement line.

The first electrical conductor layer, the second electrical conductor layer, the dielectric layer arranged between the first conductor layer and the second conductor layer and the insulator layer applied to the second conductor layer are arranged above one another in the manner of a sandwich. The coating applied at least in sections to the electrical or electronic assembly forms a measurement capacitor. When the electrical or electronic control device is heated, the dielectric layer of the coating changes its permittivity and therefore the measurement capacitor provided by the coating changes its capacitance. The change in capacitance caused is used as a measure for a change in temperature of the control device. This permits simple and reliable identification of an increase in temperature at the control device. If the change in capacitance identified or the change in temperature identified should be impermissibly high, suitable countermeasures can be taken.

According to one advantageous development, the coating is applied at least in sections to at least one of the electrically conductive conductor tracks of the assembly indirectly in such a way that a further insulator layer of the coating is arranged between the respective electrically conductive conductor track and the first electrical conductor layer of the coating. As an alternative or in addition, the coating is applied at least in sections to at least one of the electrical or electronic modules of the assembly indirectly in such a way that a further insulator layer of the coating is arranged between the respective electrical or electronic module and the first electrical conductor layer of the coating. As an alternative or in addition, the coating is applied at least in sections to the electrically insulating carrier material of the printed circuit board directly in such a way that the first electrical conductor layer of the coating is applied to the electrically insulating carrier material of the printed circuit board directly.

The coating comprises at least four layers, namely at least the first and second conductor layer, the dielectric layer arranged between said conductor layers and also the insulator layer arranged toward the outside, said insulator layer being applied to the second conductor layer in such a way that the second conductor layer is arranged between the dielectric layer and the insulator layer. If the coating in the region of electrically conductive components of the electrical electronic assembly is applied to the electrical or electronic assembly, in particular in the region of electrically conductive conductor tracks, a further insulator layer is present as fifth layer, which is arranged as the innermost layer between the respective electrically conductive component of the electrical or electronic assembly and the first conductor layer.

The evaluation unit of the control device preferably triggers a test or maintenance of the control device when the change in capacitance of the coating detected by said evaluation unit is greater than a first limit value. The evaluation unit triggers a load reduction when the detected change in capacitance of the coating is greater than a second limit value. This permits particularly advantageous triggering of countermeasures, namely when the change in capacitance is impermissibly high. Firstly, a test or maintenance of the control device can be triggered when the change in capacitance is greater than a first limit value. If the change in capacitance should become even greater and be greater than a second limit value, a load reduction can be triggered in order to prevent damage to the control device as a result of an impermissibly high change in temperature, in particular an increase in temperature.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to an electrical or electronic control device. In particular, the electrical or electronic control device is a control device of a vehicle, such as a land vehicle, aircraft or watercraft.

The invention is particularly preferably used in electrically driven vehicles in the field of an electrical or electronic control device, which is a component part of a high-voltage system. The invention can be used, for example, in a control device of a land vehicle designed as an electric vehicle or hybrid vehicle, in particular a passenger vehicle, in particular in the field of the power electronics system of a vehicle of this type.

FIG.1highly schematically shows an electrical or electronic control device10having an electrical or electronic assembly11, wherein said assembly11in the exemplary embodiment ofFIG.1comprises a printed circuit board12composed of an electrically insulating carrier material, electrically conductive conductor tracks13formed on the printed circuit board12and electrical or electronic modules14connected to the printed circuit board12and by means of the conductor tracks13. InFIG.1, said modules14are arranged on a first side12aof the printed circuit board12.

The electrical or electronic control device10furthermore has a coating15applied at least in sections to the electrical or electronic assembly11.

In the exemplary embodiment ofFIG.1, said coating15is applied over an area, in particular over the full area, to the side12bof the printed circuit board12located opposite the side12aof the printed circuit board12.

In the exemplary embodiment ofFIG.1, said coating15comprises a first electrical conductor layer16facing the electrical or electronic assembly11, a second conductive layer17facing away from the electrical or electronic assembly, a dielectric layer18arranged between the first conductor layer16and the second conductor layer17, and an insulator layer19applied to the second conductor layer17in such a way that the second conductor layer17is arranged between the dielectric layer18and the insulator layer19.

The first electrical conductor layer16, the second electrical conductor layer17, the dielectric layer18arranged between the first conductor layer16and the second conductor layer17and the insulator layer19applied to the second conductor layer17are arranged above one another in the manner of a sandwich.

The above layers16,17,18and19are accordingly applied to the side12bof the printed circuit board12in layers or in the manner of a sandwich, namely firstly the first conductor layer16, which is applied directly to the side12bof the printed circuit board12composed of the electrically insulating carrier material, then the dielectric layer18, which is applied directly to the first conductor layer16, then the second conductor layer17, which is applied directly to the dielectric layer18, and then the insulator layer19, which is applied directly to the second conductor layer17.

The coating15forms a measurement capacitor.

The control device10furthermore has an evaluation unit20, which is electrically conductively connected to the two conductor layers16,17and specifically inFIG.1by means of measurement lines21,22.

The measurement line21extends starting from the first conductor layer16through the printed circuit board12and is contact-connected to the evaluation unit20. The measurement line22extends starting from the second conductor layer17likewise through the printed circuit board12and is electrically conductively contact-connected to the evaluation unit20. The measurement line22is electrically insulated from the layers16and18.

As stated above, the evaluation unit20detects a change in capacitance of the coating15, caused in particular by an increase in temperature of the electrical or electronic assembly11, based on measurement variables tapped at the conductor layers16,17of the coating15.

When the evaluation unit determines that a detected change in capacitance of the coating15is or becomes greater than a first limit value, the evaluation unit20can trigger a test or maintenance of the control device10, for example by virtue of a fault entry being stored, which then triggers a test of the control device in a next maintenance interval.

When a detected change in capacitance of the coating15is or becomes greater than a second limit value, which is greater than the first limit value, the evaluation unit20can trigger a load reduction in order, for example, to reduce electric currents and/or electric voltages and to thus counteract an impermissibly high heating of the control device10in order to thus prevent damage to same.

FIG.2shows a further electrical or electronic control device10, which differs from the exemplary embodiment ofFIG.1in that the electrical or electronic modules14of the electrical or electronic assembly11and also the coating15are applied to the same side12bof the printed circuit board12.

Here, inFIG.2, the coating15extends over an area, namely over the full area, of the side12bof the printed circuit board12and specifically also over the electrical or electronic modules14and the electrically conductive conductor tracks13. In this case, in addition to the two conductor layers16and17, the dielectric layer18and the outer insulator layer19, the coating15comprises a further, inner insulator layer23, which is applied to the modules14and the conductor tracks13accessible at the side12b. The first conductor layer16is then arranged between the further insulator layer23and the dielectric layer18.

The evaluation unit20of the control device10is in turn electrically conductively contact-connected to the two conductor layers16and17of the coating15by means of measurement lines21and22in order to tap measurement variables and to detect a change in capacitance of the coating15, caused by an increase in temperature of the electrical or electronic assembly, on the basis of said measurement variables.

FIG.3shows a further exemplary embodiment of an electrical or electronic control device10according to the invention, wherein, inFIG.3, the coating15, which provides the measurement capacitor, is applied to the same side12bof the printed circuit board12as the electrical or electronic modules14, but outside of the region of said modules14and outside of the region of electrically conductive conductor tracks13. InFIG.3, the coating15is accordingly applied exclusively to the electrically insulating material of the printed circuit board12, with the result that the inner or further insulator layer23can be omitted.

In addition to the measurement capacitor function, the respective coating15can provide a protective function for the printed circuit board12.

As shown inFIGS.1,2and3, the coating15can be applied to the corresponding side of the printed circuit board12over an area and specifically over a full area or part of an area, alternatively in the manner of a grid so as to form a grid.

Accordingly, it lies within the scope of the present invention to apply a coating15, which forms a measurement capacitor, to an electrical or electronic assembly11of a control device10. In the event of a change in temperature, in particular an increase in temperature, in the region of the electrical or electronic assembly11, the dielectric layer18of the coating15changes its permittivity. A change in capacitance of the measurement capacitor provided by the coating15is thus brought about, which can be detected metrologically. To this end, the conductor layers16,17of the coating15are contact-connected to the evaluation unit20, which detects the change in capacitance, by means of measurement lines21,22. The change in capacitance can be translated to a change in temperature, for example, in a manner dependent on the characteristic map or in a manner dependent on the characteristic curve.

Irrespective of whether the change in capacitance or the change in temperature falls below a respective limit value, the evaluation unit20can trigger countermeasures, either in order to trigger a test or maintenance of the control device10or else to trigger a load reduction.

The invention permits a check within the shortest time to determine whether the control device10is exposed to impermissibly high heating. As a result of this, a control device10can be protected from damage in order to increase the lifetime of same.

In addition to the measurement capacitor function, the coating15can provide a mechanical protective function for the printed circuit board12.

The invention is used, in particular, in control devices of a high-voltage system of a vehicle, thus in a high-voltage system of an electric vehicle or hybrid vehicle.