Circuit board for a vehicle's lighting module

Abstract

Printed circuit board (10) for a light module (100) of a vehicle, comprising an electrical circuit (20) with a consumer (30) and at least one short-circuit section (40) connected in parallel to the consumer (30), wherein the circuit (20) has a fuse device (50) connected in series with the consumer (30) and the short-circuit section (40) for disconnecting the electrical circuit (20), and wherein the short-circuit section (40) has a first conductor surface (42) and a second conductor surface (44) separated from the first conductor surface (42) by a short-circuit gap (46), wherein the short-circuit section (40) is formed by the two adjacent conductor surfaces (42, 44).

Description

[0001] The present invention relates to a printed circuit board for a vehicle light module and to a method for manufacturing a printed circuit board for a vehicle light module.

[0002] It is generally known that printed circuit boards (PCBs) are used in vehicle lighting modules to provide the necessary basic functionalities, such as illuminating a specific area in front of and behind the vehicle, or providing warning functions in front of, behind, or to the sides of the vehicle. Such a PCB, also known as a printed circuit board, serves to represent electrical circuits using circuit boards and components. These PCBs are typically manufactured using techniques such as etching techniques on a copper layer. When installed in a vehicle lighting module, this PCB is usually housed in a waterproof enclosure to ensure adequate protection.

[0003] A disadvantage of known solutions for light modules is that it can never be completely ruled out that water will penetrate the interior of the light module despite the waterproof seal. This can happen, for example, due to minor damage to the vehicle or the light module housing. Even minor parking bumps can damage the light module housing, allowing water to enter. In a vehicle, this water is usually mixed with other substances, especially road salt. The penetrating water can therefore lead to electrochemical corrosion within the light module, particularly on the circuit board. This electrochemical corrosion can cause short circuits within the circuit board, so that, for example, the mere impact and accumulation of a water droplet on the circuit board can bridge individual traces.Corrosion on the circuit traces can also cause short circuits. This is particularly critical with components mounted on the circuit board that have very close spacing between their connecting pins, which are soldered directly onto the traces. The more complex, modern, and especially smaller the components on the circuit board are, the closer these spacings become. Common solutions use humidity sensors or fuses to detect short circuits and prevent damage to the circuit board or even the entire light module from burning out.

[0004] A disadvantage of the known solutions, however, is that the use of sensor devices and corresponding measuring amplifiers is expensive, complex, and space-consuming. The use of fuses has the disadvantage that they must be designed with relatively high tripping thresholds in the range of more than approximately 2 amps, since current spikes during normal operation of the light module must not cause the fuse to trip unnecessarily. However, if even small water droplets enter the circuit, currents below these required threshold values ​​can lead to a leakage current and consequently to a creeping short circuit, which could cause the circuit board to smolder or even start a fire.

[0005] DE 102 50 968 A1 discloses an electric light for a motor vehicle with a circuit board and a circuit arrangement, wherein the circuit arrangement has a moisture sensor which, when moisture is detected, triggers an electrical fuse via a switching amplifier.

[0006] DE 197 17 032 A1 discloses an assembly without or with a printed circuit board, which includes electrical and / or electronic components, in which and / or in which one or more means are provided for preventing or reducing the effects of moisture on conductive material.

[0007] The object of the present invention is to at least partially overcome the disadvantages described above. In particular, it is the object of the present invention to improve the protection function on the printed circuit board, especially against electrochemical corrosion, in a cost-effective and simple manner.

[0008] The foregoing problem is solved by a printed circuit board having the features of claim 1 and a method having the features of claim 9. Further features and details of the invention will become apparent from the dependent claims, the description, and the drawings. Features and details described in connection with the printed circuit board according to the invention naturally also apply in connection with the method according to the invention, and vice versa, so that the disclosure of the individual aspects of the invention always makes, or can make, reciprocal references.

[0009] A printed circuit board according to the invention for a vehicle lighting module comprises an electrical circuit. This electrical circuit is equipped with a load and at least one short-circuit section connected in parallel to the load. The printed circuit board includes a fuse connected in series with the load and the short-circuit section for disconnecting the electrical circuit. Furthermore, the short-circuit section comprises a first conductor surface and a second conductor surface separated from the first conductor surface by a short-circuit gap.

[0010] According to the invention, in addition to the known structures of an electrical circuit, a so-called short-circuit section is provided. This section, according to the invention, is defined as the technical configuration of two adjacent conductor surfaces that are electrically insulated by a short-circuit gap. In other words, no current flows through this parallel branch to the load within the electrical circuit. However, the same voltages are applied to the conductor surfaces as are generally present in the circuit. This results in the following in normal operation: current, based on the applied voltage, flows essentially exclusively through the load, and no current is transferred between the conductor surfaces via the short-circuit gap.

[0011] If the housing of the light module is damaged as described in the introduction and water penetrates it, the water can condense on the circuit board and form droplets. Such a droplet can also be located on the short-circuit section. A water droplet on the short-circuit section then bridges the short-circuit gap with the water droplet. In other words, the water droplet, which has a correspondingly increased conductivity due to the salts it contains, closes the electrical circuit across the short-circuit gap at the two conductor surfaces of the short-circuit section. In other words, a perfect short circuit is created, so that a defined and ideal short circuit now exists throughout the entire electrical circuit via the short-circuit section.This so-called ideal short circuit leads to an immediate increase in the resulting short-circuit current, so that the safety device also provided according to the invention is highly likely to actually trip.

[0012] As can be clearly seen from the preceding functional description, the invention now makes it possible to use known fuse devices with higher tripping reliability. While with the originally known solutions there was a risk that corrosion could cause small short circuits or leakage currents to lead to short-circuit currents below the tripping threshold of the fuse device, the provision of a short-circuit section according to the invention now creates a virtually ideal short circuit. Thus, if water penetrates the light module, contact with the short-circuit section immediately leads to a high short-circuit current, which is naturally above the threshold of the fuse device. A situation like that of known solutions, involving leakage currents and small or insufficient short-circuit currents, is therefore eliminated with a high degree of certainty, thereby significantly increasing the safety of a printed circuit board according to the invention.

[0013] It is of course possible to use the inventive concept of the short-circuit section on printed circuit boards in other locations and for other components in a vehicle that are exposed to water or corrosion.

[0014] For the purposes of the present invention, a consumer is in particular a light source for the light module. Thus, one or more light sources in the form of LEDs can be arranged on the circuit board. Naturally, the circuit board can preferably include a power source or a power connection that supplies the electrical circuit with the necessary voltage and current.

[0015] A safety device is defined as a technical configuration that disconnects the electrical circuit and thus the electrical circuit itself. Essentially any type of fuse can be used. In particular, fuse links or thermal fuses can be cost-effective solutions for the safety device.

[0016] A key advantage of the present invention is, among other things, its cost-neutral manufacturing. The entire circuit board and the corresponding traces of the electrical circuit can be produced, for example, by an etching process in a single copper layer. This means that the short-circuit section is also etched in one step using the same process, so that no additional costs are incurred for a circuit board according to the invention. The described function of the perfect short circuit triggers even with very small amounts of water. In particular, a single drop of water on the short-circuit section is sufficient to trigger the corresponding tripping of the safety device. Another advantage is that only liquid water causes the tripping. Known humidity sensors, which are already used in light modules, often cannot distinguish between liquid water and atmospheric humidity.This can lead to false triggering, which is virtually eliminated with a printed circuit board according to the invention. The inventive design of the printed circuit board, with its enhanced safety functionality, also enables the use of more complex circuits, particularly more modern and smaller components with smaller pin spacing.

[0017] Short-circuit gaps according to the present invention are typically produced by the same etching process used for the entire printed circuit board. The corresponding gap widths are preferably less than 1 mm, preferably in the range between 0.2 mm and 5 mm.

[0018] According to the invention, the short-circuit gap is to be provided with a particularly long length. It may be preferred if the short-circuit gap extends over the entire or substantially the entire length of the short-circuit section and, in particular, over the entire width of the printed circuit board. The greater the geometric extent of the conductor areas and the short-circuit gap, the higher the probability that the intruding water droplet will actually form the perfect short circuit as described.

[0019] It can be advantageous if, in a printed circuit board according to the invention, the two conductor surfaces of the at least one short-circuit section are interlocked with each other, separated by the short-circuit gap. Interlocking allows for a greater overall length of the short-circuit gap over the same length. The distance between the two conductor surfaces, which is defined by the width of the short-circuit gap, remains the same or substantially the same. Consequently, the short-circuit bridge formed by the water droplet in a perfect short circuit is more likely to occur.

[0020] Another way to achieve advantages within the scope of the present invention is to have the two conductor surfaces of the printed circuit board according to the invention have a comb-like structure separated by the short-circuit gap. This is a similar solution to the toothed design described in the preceding paragraph. A straight or angled comb can be formed here, which in particular has a similar toothing pattern to that described in the preceding paragraph. Accordingly, a significant lengthening of the short-circuit gap can also be achieved here, reducing the risk that a water droplet that has penetrated the circuit will not form a short-circuit bridge between the two conductor surfaces.

[0021] A further advantage is that, in a printed circuit board according to the invention, the conductor areas on both sides of the short-circuit gap have a symmetrical or substantially symmetrical planar extent. This means that the two conductor areas are essentially mirror images of each other. As a side effect, this results in a constant width of the short-circuit gap along the entire short-circuit section. Preferably, the conductor areas are also provided to be of sufficient size to ensure that the current-carrying area created by the contact between a water droplet and the respective conductor area is sufficiently large. Preferably, the conductor area is larger than or equal to the area adjacent to the short-circuit gap compared to the ideal droplet shape that results from the expected droplet angle at the edge when the droplet contacts the conductor area.Such an idealized smallest droplet accordingly leads to a full coverage of the conductor surface, so that the current entry and exit into the water droplet and from the water droplet can occur through essentially the same area.

[0022] A further advantage arises when, in a printed circuit board according to the invention, at least one short-circuit section is arranged at the edge of the board. This is particularly relevant because printed circuit boards are often arranged not horizontally, but vertically or at an angle within the light module. Arranging the short-circuit section at the edge allows it to be positioned in a lower area relative to gravity when the printed circuit board is inserted. Any water that penetrates will then collect in this lower area by gravity, thus significantly increasing the probability of the described short-circuit bridge forming at the short-circuit section.

[0023] A further advantage can be achieved if, in a printed circuit board according to the invention, at least one short-circuit section extends over the entire or substantially the entire width of the printed circuit board. This also leads to a geometric enlargement of the short-circuit section and thus to an increase in the probability of the described short circuit forming when water enters the board.

[0024] It is also advantageous if a printed circuit board according to the invention has at least two short-circuit sections provided, which are arranged on different edges, in particular on opposite edges, of the printed circuit board. This means that the printed circuit board now has a dual application. If, for example, a printed circuit board for the left headlight or the left taillight of a vehicle is arranged essentially vertically, the first short-circuit section, which is accordingly located at the bottom, serves the function according to the invention. On the opposite right side of the vehicle, the identical printed circuit board can now be used in a flexible manner, since, due to a 180° rotation in the installation position, the short-circuit section is now located at the bottom on the other edge and fulfills the described safety function.This design allows for universal use of the circuit board on both sides of the vehicle for the corresponding light modules.

[0025] It is further advantageous if, in a printed circuit board according to the invention, the conductor areas are formed as a copper layer of the circuit board with a free surface. As already explained in the introduction, the short-circuit section can thus be formed in conjunction with the electrical circuitry using a simple etching technique. A free surface, in particular, means the absence of an insulating layer on the conductor areas. Specifically, no solder mask is provided in this area.

[0026] Another object of the present invention is a method for manufacturing a printed circuit board for a vehicle light module, comprising the following steps: - Creating a circuit on the printed circuit board with a connection for a load, at least one short-circuit section connected in parallel to the load and a connection for a fuse device connected in series to the connection for the load and to the short-circuit section, wherein the short-circuit section has a first conductor surface and a second conductor surface separated from the first conductor surface by a short-circuit gap, - Connecting the consumer to the consumer connection, - Connecting the fuse to the fuse terminal.

[0027] A method according to the invention is particularly useful for manufacturing a printed circuit board according to the invention. Accordingly, a method according to the invention offers the same advantages as those already explained in detail with reference to a printed circuit board according to the invention.

[0028] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the description can each be essential to the invention individually or in any combination. The drawings schematically show: Fig. 1 a first embodiment of an electrical circuit on a printed circuit board according to the invention, Fig. 2 another embodiment of a printed circuit board according to the invention, Fig. 3 a possible embodiment of a short-circuit section, Fig. 4 another embodiment of a short-circuit section, Fig. 5 a schematic representation of the short circuit caused by a water droplet in top view, and Fig. 6 the situation according to Fig. 6 in a schematic cross-section.

[0029] In Fig. Figure 1 schematically illustrates the operation of the present invention. An electrical circuit 20 receives voltage and current from a power connection 22. The main part of this electrical circuit 20 is provided via a fuse 50 and a load 30 in the form of several LEDs. A short-circuit section 40 according to the invention is provided in parallel with the load 30 and in series with the fuse 50. This section has two conductor surfaces 42 and 44, which are separated from each other by a short-circuit gap 46. Under normal conditions, the separation provided by the short-circuit gap 46 is sufficient to ensure electrical isolation of this part of the electrical circuit 20. In such a situation, current flows only through the load 30.

[0030] Fig. Figure 2 shows a printed circuit board 10 according to the invention in a light module 100 according to the invention in a vertical configuration. It is also clearly visible how, in this case, two short-circuit sections 40 are connected in parallel to a load 30, here in the form of, for example, an LED device. The electrical circuit 20 further includes at least one fuse 50, which is connected in series with the two short-circuit sections 40 and the load 30. Here again, a power connection 22 is provided for the supply of voltage and current. In this embodiment, it is clearly visible that when water penetrates the vertical configuration, these water droplets flow downwards on the printed circuit board and collect in the lower area, i.e., here at the lower short-circuit section 40.If the described short-circuit bridge now forms, a current can flow between the two conductor surfaces 42 and 44 of the lower short-circuit section 40, so that a high short-circuit current is now present for tripping the fuse device 50. The embodiment of the... Fig. 2 can also be used rotated by 180°, i.e., with the power connections 22 on the left and the load on the right. This allows for universal use of light modules 100 in vehicles on both sides of the vehicle.

[0031] In Fig. Figure 3 shows a particularly simple embodiment of a short-circuit section 40. A purely linear short-circuit gap 46, separating the two conductor surfaces 42 and 44, can also fulfill the function according to the invention.

[0032] Fig. Figure 4 shows, in addition to the comb-like structure of the Fig. 1 and Fig. 2 another, namely interlocking, possibility of forming the short-circuit gap 46. In comparison to the embodiment of the Fig. Figure 3 shows how a significant extension of the short-circuit gap 46 and thus an improvement of the safety functionality according to the invention can already be achieved here.

[0033] The Fig. 5 and Fig. Figure 6 shows a possible situation of a short-circuit bridge at the short-circuit section 40. Here, a water droplet 200 has struck the short-circuit section 40, forming corresponding contact surfaces with the two conductor surfaces 42 and 44. This allows an electric current to flow through the water droplet, and the described short circuit for tripping the fuse device 50 is thus present.

[0034] The preceding explanation of the embodiments describes the present invention solely by way of examples. Naturally, individual features of the embodiments can be freely combined with one another, provided this is technically feasible, without departing from the scope of the present invention. Reference symbol list 10 circuit boards 12 Rand 14 width 20 electrical circuits 22 Power connection 30 consumers 40 Short-circuit section 42 first conductor surface 44 second conductor surface 46 Short-circuit gap 50 safety device 100 light modules 200 water drops

Claims

Printed circuit board (10) for a light module (100) of a vehicle, comprising an electrical circuit (20) with a consumer (30) and at least one short-circuit section (40) connected in parallel to the consumer (30), wherein the circuit (20) has a fuse device (50) connected in series with the consumer (30) and the short-circuit section (40) for disconnecting the electrical circuit (20), and wherein the short-circuit section (40) has a first conductor surface (42) and a second conductor surface (44) separated from the first conductor surface (42) by a short-circuit gap (46), wherein the short-circuit section (40) is formed by the two adjacent conductor surfaces (42, 44). Printed circuit board (10) according to claim 1, characterized in that the two conductor surfaces (42, 44) of the at least one short-circuit section (40) are interlocked with each other by means of the short-circuit gap (46). Printed circuit board (10) according to one of the preceding claims, characterized in that the two conductor surfaces (42, 44) have a comb-like structure separated by the short-circuit gap (46). Printed circuit board (10) according to one of the preceding claims, characterized in that the conductor surfaces (42, 44) on both sides of the short-circuit gap (46) have a symmetrical or substantially symmetrical planar extent. Printed circuit board (10) according to one of the preceding claims, characterized in that the at least one short-circuit section (40) is arranged at the edge (12) of the printed circuit board (10). Printed circuit board (10) according to one of the preceding claims, characterized in that the at least one short-circuit section (40) extends over the entire or substantially the entire width (14) of the printed circuit board (10). Printed circuit board (10) according to one of the preceding claims, characterized in that at least two short-circuit sections (40) are provided, which are arranged on different side edges, in particular on opposite side edges, of the printed circuit board (10). Printed circuit board (10) according to one of the preceding claims, characterized in that the conductor surfaces (42, 44) are formed as a copper layer of the printed circuit board (10) with a free surface. Method for manufacturing a printed circuit board (10) for a light module (100) of a vehicle, comprising the following steps: - Creating a circuit (20) on the printed circuit board (10) with a connection for a consumer (30), at least one short-circuit section (40) connected in parallel to the consumer (30) and a connection for a fuse device (50) connected in series to the connection for the consumer (30) and to the short-circuit section (40), wherein the short-circuit section (40) has a first conductor surface (42) and a second conductor surface (44) separated from the first conductor surface (42) by a short-circuit gap (46), wherein the short-circuit section (40) is formed by the two adjacent conductor surfaces (42, 44), - Connecting the consumer (30) to the connection for the consumer (30), - Connecting the fuse device (50) to the connection for the fuse device (50). Method according to claim 9, characterized in that a printed circuit board (10) is manufactured having the features of one of claims 1 to 8.

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