Control device for a motor vehicle

Abstract

The invention relates to a control device (12) for a motor vehicle, the control device comprising a printed circuit board (10), the printed circuit board having a first side (14) and an edge (16), wherein the first side (14) of the printed circuit board (10) is delimited by the edge (16); at least one electronic component (18) which is arranged on the first side (14) of the printed circuit board (10) and is electrically conductively connected to the printed circuit board (10); a first conductor loop (20) which is designed as a resistor and is arranged on the first side (14) of the printed circuit board (10), wherein the first conductor loop (20) is arranged between the edge (16) and the electronic component (18); and an injection-molded cover (26) of the printed circuit board (10), wherein the injection-molded cover (26) at least surrounds the first side (14), the at least one electronic component (18) and the first conductor loop (20).

Description

Technical Field

[0001] The invention relates to a control device for a motor vehicle, wherein the control device has an injection-molded or overmolded printed circuit board and a conductor loop designed as a resistor is formed on the printed circuit board, wherein leaks between the injection-molded coating and the printed circuit board can be detected by measuring the resistance of the conductor loop. Background Art

[0002] Control devices are known, which have a housing and a printed circuit board arranged within the housing. Due to the housing, such control devices can have increased tightness. In the process of weight reduction and in order to reduce the size of the components, control devices or printed circuit boards of the control devices are injection-molded with plastic and are therefore constructed in a medium-tight manner. However, if the adhesion between the printed circuit board and the injection-molded coating is to be weakened, a gap may form between the printed circuit board and the injection-molded coating. Corrosive media, such as oil, may penetrate through this gap and damage the contacts of the electronic components arranged on the printed circuit board, whereby the control device may suddenly and unexpectedly fail. Summary of the invention

[0003] The object of the present invention is to provide a control unit for a motor vehicle, the leak tightness of which can be monitored in a simple manner.

[0004] This object is achieved by a control device for a motor vehicle. Preferred developments of the invention are explained in further exemplary embodiments and in the following description and figures, wherein each feature may represent an aspect of the invention both individually and in combination.

[0005] According to the invention, a control device for a motor vehicle is provided, the control device having a printed circuit board, the printed circuit board having a first side and an edge, wherein the first side of the printed circuit board is delimited by the edge,

[0006] at least one electronic component which is arranged on a first side of the printed circuit board and is electrically conductively connected to the printed circuit board,

[0007] A first conductor loop, which is arranged on a first side of the printed circuit board, wherein the first conductor loop is arranged between the edge and the electronic component, and an injection-molded covering of the printed circuit board, wherein the injection-molded covering at least surrounds and / or encapsulates the first side, at least one electronic component and the first conductor loop.

[0008] In other words, one aspect of the invention is to provide a control device for a motor vehicle, which has at least one printed circuit board. The printed circuit board has a first side. This first side is also usually referred to as the upper side. The printed circuit board also has an edge, which delimits the first side of the printed circuit board. The edge can therefore also preferably be referred to as an edge. The edge therefore represents an external terminal (Abschluss) of the printed circuit board.

[0009] At least one electronic component is arranged on the first side of the printed circuit board and is electrically conductively connected to the printed circuit board. Usually, the first side has a plurality of electronic components arranged at intervals from each other on the first side. These components are also usually referred to as electronic assemblies.

[0010] Furthermore, it is provided that a first conductor loop configured as a resistor is arranged on a first side of the printed circuit board, wherein the first conductor loop is arranged between the edge and the electronic component. In other words, the distance between the first conductor loop and the edge in a plane parallel to the printed circuit board is smaller than the distance between the electronic component and the edge.

[0011] The first side of the printed circuit board is injection molded. The injection molding of the printed circuit board is also called "overmolding". The injection molded coating (Umspritzung) is constructed so that the injection molded coating at least surrounds the electronic component and the first conductor loop. If the adhesion between the injection molded coating and the printed circuit board is weakened, so that a small gap is formed between the injection molded coating and the printed circuit board, corrosive media, such as oil, may penetrate into the gap and cause corrosion of the first conductor loop. Due to the corrosion of the first conductor loop, the resistance of the first conductor loop changes. Specifically, the resistance of the first conductor loop increases. Since the distance between the edge and the conductor loop is smaller than the distance between the edge and the electronic component, the defect (Defekt) of the adhesion between the injection molded coating and the printed circuit board can be detected and signaled before the electronic components important for the operation of the control device are damaged due to the penetration of the corrosive medium. In this way, a control device is provided, the sealing of which can be monitored in a simple manner.

[0012] An advantageous development of the invention is that the first conductor loop is open-circuited and is connected by means of a through-contact for four-point resistance measurement. In other words, the first conductor loop is arranged on a first side of the printed circuit board. The measuring points of the first conductor loop are guided from the first side to a second side arranged at a distance from the first side via through-contacts through the printed circuit board. In this way, the resistance of the first conductor loop can be measured from the second side, so that the injection-molded cover on the first side of the printed circuit board is not interrupted by the contact device for resistance measurement of the first conductor loop and is therefore weakened.

[0013] An advantageous improvement of the invention is that the printed circuit board has a second side arranged at a distance from the first side, the second side being bounded by an edge, and the second conductor loop being arranged on the second side at a distance from the edge. The second side is also usually referred to as the bottom side. The second side is arranged opposite the first side. The second conductor loop arranged on the second side is preferably designed as an open circuit and has four contact points for four-point resistance measurement. The resistance of the second conductor loop can be measured separately from the first conductor loop by the second conductor loop, so that defects can be detected first depending on the points at which the adhesion between the injection molded cover and the printed circuit board drops.

[0014] In principle, it can be provided that both the first side and the second side of the printed circuit board are injection molded. In other words, it can be provided that the first conductor loop is injection molded or overmolded on the first side of the printed circuit board and the second conductor loop is likewise injection molded or overmolded on the second side of the printed circuit board. The material used for injection molding the first side and the second side can be the same. However, it is also conceivable that the first side is injection molded with a first material and the second side is injection molded with a second material different from the first material.

[0015] An advantageous improvement of the invention is that the printed circuit board is arranged on the substrate via an intermediate layer, wherein the intermediate layer is arranged between the second side and the substrate. The intermediate layer can preferably be configured as a thermally conductive adhesive and / or a laminate and / or a no-flow prepreg. The substrate is preferably constructed of aluminum so that heat can be dissipated through the substrate. The substrate can therefore also be considered and / or configured as a cooler.

[0016] It is particularly preferred that recesses and / or openings are provided in the substrate and in the intermediate layer, so that access to the contact points of the second conductor loop is provided via the recesses and / or access to the contact points of the first conductor loop is provided in the case of a through-contact of the first conductor loop, so that corresponding resistance measurements can be performed on the first conductor loop and / or the second conductor loop.

[0017] It is conceivable that the contact points of the first conductor loop formed on the first side of the printed circuit board are accessible from the first side. For this purpose, it is provided that the injection molding is omitted on the first side of the printed circuit board in the region of the contact points of the first conductor loop so that the contact points are accessible and can be acted upon with voltage for a four-point resistance measurement.

[0018] A preferred improvement of the present invention is that the contact points of the first conductor loop and / or the second conductor loop can be loaded with voltage through the plug connector and / or the plug connector of the printed circuit board in order to determine the respective insulation resistance of the first conductor loop and / or the second conductor loop. In this way, in addition to electrically contacting the printed circuit board through the plug connector, the first conductor loop and / or the second conductor loop can also be electrically contacted in order to detect the line resistance of the first conductor loop and / or the second conductor loop. In principle, the first conductor loop and the second conductor loop can be constructed so that the resistance, specifically the line resistance, can be determined through the respective conductor loops. In addition, the conductor loop must be corrodible relative to the medium surrounding the control device, so that if the medium reaches the conductor loop through the gap between the injection molded cover and the printed circuit board, the line resistance of the respective conductor loop can change. An advantageous improvement of the present invention is that the first conductor loop and / or the second conductor loop have silver, brass, copper and / or silver alloys. Silver, brass, copper and / or silver alloys can be corroded by oil, for example, so that when the conductor loop constructed in this way comes into contact with oil, the conductor loop changes its line resistance. The resistance of the first conductor loop and / or the second conductor loop can be determined in a simple manner by a four-point resistance measurement. Copper is cheaper than silver, so that the costs of the control device can be reduced.

[0019] In a preferred development of the invention, it is provided that the width and / or thickness of the first conductor loop and / or the second conductor loop is less than 500 μm, preferably less than 250 μm and particularly preferably less than 100 μm. The smaller the cross section, width or thickness of the first conductor loop or the second conductor loop, the more sensitive the electrical resistance of the conductor loop is, so that even the smallest irregularities can be detected. Furthermore, material and costs can be reduced with a reduced conductor loop cross section.

[0020] In an advantageous improvement of the present invention, it is provided that a plurality of first conductor loops arranged at intervals from each other are arranged on a first side, and / or a plurality of second conductor loops arranged at intervals from each other are arranged on a second side. This means that, for example, two or three or even a plurality of first conductor loops are arranged side by side and / or constructed on a first conductor side, wherein a distance is formed between these individual first conductor loops respectively. The distance between the first conductor loops on the first side is preferably greater than 100 μm and less than 750 μm, preferably greater than 150 μm and less than 500 μm, wherein the boundaries are included together. The resistance of each individual first conductor loop is detected and monitored. The same construction and / or implementation also applies to the second conductor loops arranged on the second side. In this way, preferably by measuring the resistance of the first conductor loops arranged side by side, the progress of the damage to the adhesion between the injection molded coating and the first side in a direction parallel to the plane of the printed circuit board can be detected. The corresponding content applies to the second side of the printed circuit board. Based on the change in resistance of the first and / or second conductor loop in a direction parallel to the plane of the printed circuit board, a loss of adhesion between the injection-molded coating and the printed circuit board can be signaled. If, for example, the adhesion between the injection-molded coating and the printed circuit board is weakened only in the edge area, so that a corrosive medium penetrates through the gap between the injection-molded coating and the printed circuit board and causes a change in the resistance of the first conductor loop with the smallest distance from the edge, a signal can be output, for example, that the control device should be checked at the next maintenance interval. If the adhesion between the injection-molded coating and the printed circuit board progresses so that the first conductor loop has an increased resistance toward the electronic component, a signal and / or message can be output that the workshop should be visited as soon as possible to check the control device. In this way, the risk of sudden failure of the control device without warning can be reduced.

[0021] An advantageous improvement of the present invention is that the control device is constructed without a housing. In other words, the printed circuit board with the electronic components arranged thereon is not surrounded by a housing part with a housing wall to protect the electronic components from external influences. Instead, the control device with the electronic components arranged thereon or the printed circuit board of the control device is protected from external media by the injection molding coating. By constructing the control device without a housing, not only the manufacturing costs of the control device but also the installation space of the control device can be reduced.

[0022] The invention furthermore relates to a motor vehicle having a control device according to the invention.

[0023] An advantageous improvement of the present invention is that a warning signal can be output in the event of a change in the resistance of the first conductor loop and / or the second conductor loop. In other words, the detected change in the resistance of the first conductor loop and / or the second conductor loop can be communicated to the driver of the motor vehicle via a corresponding signal, so that a workshop can be visited promptly in order to replace the defective control device early. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further features of the invention are derived from the dependent claims and the following embodiments. The embodiments should not be understood as limiting, but rather as exemplary. The embodiments should enable a person skilled in the art to carry out the invention. The applicant reserves the right to make one or more of the features disclosed in the embodiments the subject of a patent claim or to incorporate such features into existing patent claims. The embodiments are explained in more detail with reference to the figures.

[0025] In the diagram:

[0026] Figure 1 A top view showing a printed circuit board of a control device according to a preferred embodiment of the present invention;

[0027] Figure 2 Shown by Figure 1 A cross section of a printed circuit board of a control device shown in;

[0028] Figure 3 A detailed view of a section through the printed circuit board in the edge region of the printed circuit board is shown;

[0029] Figure 4 shows a longitudinal section through a printed circuit board of a control device according to a second preferred embodiment of the present invention;

[0030] Figure 5 Shown is a longitudinal section through a printed circuit board of a control device according to a third preferred exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0031] exist Figure 11 shows a top view of a printed circuit board 10 for a control device 12 of a motor vehicle. The printed circuit board 10 has a first side 14 and an edge 16. The first side 14 is, for example, the upper side of the printed circuit board 10. The edge 16 delimits the first side 14 of the printed circuit board 10 or the printed circuit board 10. In other words, the edge 16 is the outer edge of the printed circuit board 10. A plurality of electronic components 18 are arranged on the first side 14 of the printed circuit board 10. The electronic components 18 are connected to the printed circuit board 10 not only mechanically but also electrically conductively. It can also be seen that a first conductor loop 20 designed as a resistor is arranged on the first side 14 of the printed circuit board 10, wherein the first conductor loop 20 is arranged between the edge 16 of the printed circuit board 10 and the electronic components 18. In other words, the distance between the edge 16 and the first conductor loop 20 in a direction parallel to the plane of the printed circuit board 10 is smaller than the corresponding distance between the edge 16 and the electronic components 18.

[0032] The first conductor loop 20 is designed as an open conductor loop and has four contact points 22 for four-point resistance measurement. The four-point resistance measurement of a conductor loop is a known measurement method.

[0033] exist Figure 2 It is shown in Figure 1 . The printed circuit board 10 is configured as a multilayer printed circuit board and has a plurality of conductor tracks 24 arranged spaced apart from one another in a direction perpendicular to the plane of the printed circuit board 10. The electronic component 18 is arranged on the first side 14 of the printed circuit board 10 and a first conductor loop 20 is configured near the edge 16 of the first side 14 of the printed circuit board 10. An injection molded coating 26 is arranged on the first side 14 of the printed circuit board 10, wherein the injection molded coating 26 is also referred to as an "overmold". The injection molded coating 26 is configured so that at least the electronic component 18 and the first conductor loop 20 are injection molded on the first side 14 of the printed circuit board 10. For example, the injection molded coating 26 can be a plastic, a synthetic resin or a resin. In this way, the contact of the electronic component 18 on the printed circuit board 10 should be protected from damage by external media.

[0034] Compared to the electronic component 18, the first conductor loop 20 has a reduced or smaller distance from the edge 16. In this way, possible leaks due to reduced adhesion between the injection-molded cover 26 and the first side 14 of the printed circuit board 10 can be detected by measuring the resistance of the first conductor loop 20 when aggressive media penetrate through the leaks.

[0035] Typically, the control device 12 is exposed to corrosive media, such as oil, which penetrate into the gap between the injection-molded cover 26 and the first side 14 of the printed circuit board 10 as soon as a leak occurs and corrodes the first conductor loop 20, which is made of copper, for example. In the process, the resistance of the first conductor loop 20 increases. Based on this resistance measurement and the change in the resistance of the first conductor loop 20, a signal can be output that signals damage to the control device 12, so that the control device can be replaced in good time before the contact of the electronic components 18 on the printed circuit board 10 is damaged by the corrosive medium.

[0036] Figure 3 Show Figure 2 1 shows a fragment of a printed circuit board 10 in the region of a first conductor loop 20. The first conductor loop 20 is arranged on the first side 14 of the printed circuit board 10 at a distance from the edge 16. The injection molded coating 26 is preferably formed on the entire first side 14 in order to be able to obtain the greatest possible adhesion to the first side 14. However, it is not mandatory to apply the injection molded coating 26 to the entire first side 14. On the contrary, the injection molded coating 26 can also be concentrated on the important components 18 to be insulated. Here, the injection molded coating 26 can also be guided over the first conductor loop 20 so that it has a minimum material thickness a between the edge 16 and the first conductor loop 20. In the present embodiment, the minimum material thickness a is approximately 500 μm.

[0037] exist Figure 4 , a section through a printed circuit board 10 of a control device 12 in a second embodiment is shown. Figure 2 The printed circuit board 10 shown in FIG. Figure 4 The printed circuit board 10 of FIG. 1 has a second side 28 arranged at a distance from the first side 14. A second conductor loop 30 is arranged on the second side 28, wherein the second conductor loop 30 is arranged at a distance from the edge 16 of the printed circuit board 10. The printed circuit board 10 is arranged on a substrate 34 in a material-dependent manner via an intermediate layer 32, which is preferably designed as a thermally conductive adhesive. The substrate 34 is preferably made of aluminum and serves as a cooler for the control device 12. It can also be seen that the first conductor loop 20 is guided to the second side 28 by means of a through-contact, so that the resistance of the first conductor loop 20 can be measured from the second side 28. For this purpose, corresponding openings 36 are provided in the substrate 34, through which access to the contact points 22 is possible for measuring the line resistance of the first conductor loop 20. It should be noted here that, although not shown, the second conductor loop 30 also has contact points for four-point resistance measurement in the region of the openings 36 on the second side 28.

[0038] The injection molded coating 26 is not only arranged on the first side 14 of the printed circuit board 10, but is also guided around the printed circuit board 10 to the substrate 34. As soon as the adhesion between the injection molded coating 26 and the substrate 34 weakens and corrosive media penetrate between the injection molded coating 26 and the substrate 34, leaks can be detected in a first step by the second conductor loop 30, wherein the resistance of the second conductor loop 30 is checked and the change in resistance is detected. In this way, a possible failure of the control device 12 can be detected at an early stage, so that the control device 12 can be replaced in time.

[0039] exist Figure 5 1 shows a longitudinal section through a printed circuit board 10 according to a third exemplary embodiment. The printed circuit board 10 has a plurality of electronic components 18 both on the first side 14 and on the second side 28. A first conductor loop 20 is arranged on the first side 14 at a distance from the edge 16. A second conductor loop 30 is arranged on the second side 28 at a distance from the edge 16. Both the first side 14 and the second side 28 of the printed circuit board 10 are protected from external media by an injection-molded coating 26. A voltage can be applied to the contact points 22 of the first conductor loop 20 and the second conductor loop 30 via a plug connector (not shown) of the printed circuit board 10 in order to be able to detect and / or determine the respective line resistances of the first conductor loop 20 and the second conductor loop 30.

Claims

1. A control device (12) for a motor vehicle, the control device comprising: A printed circuit board (10) having a first side (14) and an edge (16), wherein the first side (14) of the printed circuit board (10) is bounded by the edge (16), at least one electronic component (18) which is arranged on a first side (14) of the printed circuit board (10) and is electrically conductively connected to the printed circuit board (10), a first conductor loop (20) arranged on a first side (14) of the printed circuit board (10), wherein the first conductor loop (20) is arranged between the edge (16) and the electronic component (18), wherein the distance between the first conductor loop and the edge in a plane parallel to the printed circuit board is smaller than the distance between the electronic component and the edge, and an injection-molded covering (26) of the printed circuit board (10), wherein the injection-molded covering (26) at least surrounds the first side (14), the at least one electronic component (18) and the first conductor loop (20), The first conductor loop (20) has contact points (22) for measuring resistance.

2. The control device according to claim 1, characterized in that The first conductor loop (20) is open-circuited and connected by means of plated-through contacts for a four-point resistance measurement.

3. The control device according to claim 1 or 2, characterized in that: The printed circuit board (10) has a second side (28) which is arranged at a distance from the first side (14), the second side being delimited by the edge (16), and a second conductor loop (30) is arranged on the second side (28) at a distance from the edge.

4. The control device according to claim 3, characterized in that The printed circuit board (10) is arranged on a substrate (34) via an intermediate layer (32), wherein the intermediate layer (32) is arranged between the second side (28) and the substrate (34).

5. The control device according to claim 3, characterized in that: The first conductor loop (20) and / or the second conductor loop (30) comprises silver, copper and / or a silver alloy.

6. The control device according to claim 3, characterized in that The first conductor ring (20) and / or the second conductor ring (30) comprises brass.

7. The control device according to claim 3, characterized in that The width and / or thickness of the first conductor loop (20) and / or the second conductor loop (30) is / are less than 500 μm.

8. The control device according to claim 3, characterized in that A plurality of first conductor loops (20) arranged at a distance from one another are arranged on the first side (14), and / or a plurality of second conductor loops (30) arranged at a distance from one another are arranged on the second side (28).

9. The control device according to claim 1 or 2, characterized in that: The control device (12) is designed without a housing.

10. The control device according to claim 3, characterized in that A voltage can be applied to the contact points (22) of the first conductor loop (20) and / or the second conductor loop (30) via a plug connector and / or a plug connector of the printed circuit board (10) in order to detect and / or determine the respective line resistance of the first conductor loop (20) and / or the second conductor loop (30).

11. A motor vehicle having a control device (12) according to any one of claims 1 to 10.

12. The motor vehicle according to claim 11, characterized in that In the event of a change in the resistance of the first conductor loop (20) and / or, if a second conductor loop (30) is provided, in the event of a change in the resistance of the second conductor loop (30), a warning signal can be output.

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