Component and method for assembling a component with improved heat dissipation

Abstract

The invention relates to a component, in particular a control unit, which comprises: - a housing with a base part (16, 33) and a cover element (23, 34) which is designed as a heat sink or includes at least one heat sink and has at least one contact surface for heat dissipation, and - a circuit board (14, 29) which is fixedly arranged inside the housing and has at least one heat dissipation point facing the cover element (23, 34) for heat dissipation, - wherein the base part (16, 33) and the cover element (23, 34) have a guide device (25, 35) to guide the cover element (23, 34) towards the base part (16, 33), - wherein the cover element (23, 34) placed on the base part (16, 33) is arranged with respect to the base part (16, 33) such that the at least one contact surface of the cover element (23, 34) rests against the at least one heat dissipation point of the printed circuit board (14, 29), so that a thermal contact is established between the at least one contact surface of the cover element (23, 34) and the at least one heat dissipation point of the printed circuit board (14, 29).

Description

Technical field

[0001] The invention relates to a component assembly comprising a base part, a printed circuit board, and a cover element. Furthermore, the invention relates to a method for assembling a component assembly starting from a base part, a printed circuit board, and a cover element. Technical background

[0002] When assembling modules consisting of a base, a printed circuit board (PCB), and a cover element that acts as a heat sink or incorporates a heat sink, the question arises as to the best assembly sequence. One possible approach is to first mount the PCB to the cover element.

[0003] However, it is often necessary to first mount the circuit board onto the base, for example, onto a section of a housing, in order to connect electrical leads directly to the circuit board. For example, with an inverter, it is advantageous to connect the stator wires directly to the circuit board. Only after the electrical connections are made is the cover element placed onto the base. This assembly sequence, however, has the disadvantage that the tolerance of the circuit board contributes to the tolerance chain, so that, for example, a layer of thermal paste formed between the circuit board and the cover element has a comparatively high tolerance that exceeds the desired value.

[0004] The object of the invention is therefore to provide a component and a method for assembling the component, to simplify electrical contacting of the circuit board and at the same time to ensure good heat dissipation. Disclosure of the invention

[0005] The invention relates to a component, in particular a control unit, which comprises: - a housing with a base part and a cover element designed as a heat sink or comprising at least one heat sink and having at least one contact surface for heat dissipation, and - a circuit board which is fixedly arranged inside the housing and has at least one heat dissipation point facing the cover element, designed for heat dissipation, - wherein the base part and the lid element have a guide device to guide the lid element towards the base part, - wherein the cover element placed on the base part is arranged with respect to the base part such that the at least one contact surface of the cover element rests against the at least one heat dissipation point of the printed circuit board, so that a thermal contact is established between the at least one contact surface of the cover element and the at least one heat dissipation point of the printed circuit board.

[0006] When assembling the assembly according to the embodiments of the present invention, the printed circuit board (PCB) is first attached to the base part. This has the advantage that electrical connecting lines can be connected directly to the PCB. In this way, interfaces can be eliminated, thereby reducing the number of components. Only after the PCB has been electrically contacted is the cover element, which is designed as a heat sink or includes at least one heat sink, placed onto the base part in such a way that at least one contact surface of the cover element is pressed against at least one heat dissipation point of the PCB. The PCB is thus installed with contact from both the base part side and the cover element side. This ensures that the tolerance of the PCB no longer contributes to the tolerance chain.Regardless of the printed circuit board's thickness tolerance, uniform thermal contact across the board is ensured. This improves heat dissipation from the assembly.

[0007] Furthermore, the invention relates to a method for assembling a component starting from a base part, a printed circuit board and a cover element which is designed as a heat sink or includes at least one heat sink, wherein the method comprises the following steps: - Applying the printed circuit board to the designated support points on the base part, - Placing the cover element onto the base part with the circuit board, wherein the cover element engages with the base part when placed onto the base part and is guided to move in the direction towards the base part, - Pressing the cover element placed on the base part against the base part, wherein at least one contact surface of the cover element is pressed against the at least one heat dissipation point of the circuit board in such a way that a thermal contact is established between the at least one contact surface of the cover element and the at least one heat dissipation point of the circuit board via a layer of thermal paste, and - in a position where a thermal contact is formed between the contact surfaces of the cover element and the heat dissipation points of the circuit board, fixing the cover element relative to the base part.

[0008] It is advantageous if the printed circuit board is arranged on designated support points of the base part. Preferably, the at least one support point comprises at least one dome for supporting the printed circuit board. More preferably, the at least one support point comprises a fully or partially circumferential rim for supporting the printed circuit board.

[0009] It is advantageous to have components attached to the side of the circuit board facing the base, with the heat dissipation points designed to dissipate the heat generated by the components.

[0010] Preferably, the circuit board is screwed to the base part.

[0011] According to a preferred embodiment, the assembly comprises several printed circuit boards (PCBs). Preferably, the assembly comprises several PCBs that are connected to one another by means of support elements. Since the support surfaces of the PCBs are aligned vertically, less installation space is required. More preferably, the assembly comprises several PCBs, wherein the PCBs can be connected to form a pre-assembly unit by means of support elements before being inserted into the base part. The pre-assembly unit can be functionally tested before installation. It is advantageous if the pre-assembly unit, which consists of several PCBs and support elements, can be inserted into a receiving area of ​​the base part.

[0012] According to a preferred embodiment, the cover element is movable essentially perpendicular to the circuit board.

[0013] Preferably, a thermal contact is established between the at least one contact surface of the cover element and the at least one heat dissipation point of the printed circuit board (PCB) via a layer of thermal paste. According to a preferred embodiment, the cover element, which is placed on the base part, can be pressed against the base part in such a way that a layer of thermal paste of a defined thickness is formed between the contact surfaces of the cover element and the heat dissipation points of the PCB. Preferably, the cover element, when placed on the base part, can be pressed against the base part with a defined contact force. Preferably, the layer of thermal paste has a thickness of 0.25 mm ± 0.05 mm. This enables reliable heat dissipation.

[0014] According to a preferred embodiment, the at least one heat dissipation point comprises one or more heat conducting elements which are arranged on the side of the circuit board facing the cover element and are designed to form thermal contact with contact surfaces of the cover element.

[0015] Preferably, the lid element has a first guide profile that surrounds the edge of the lid element completely or partially, and the base part has a second guide profile that surrounds the edge of the base part completely or partially, wherein the first guide profile of the lid element engages with the second guide profile of the base part when placed on the base part, and the lid element is guided and movable in the direction towards the base part.

[0016] It is advantageous if the assembly includes a fixing device to secure the cover element relative to the base part in a position where thermal contact is formed between the contact surfaces of the cover element and the heat dissipation points of the printed circuit board. Preferably, the cover element is designed to be fixed relative to the base part in a position where a layer of thermal paste of a predetermined thickness is formed between the contact surfaces of the cover element and the heat dissipation points of the printed circuit board. According to a preferred embodiment, the cover element and the base part can be welded together in the position where thermal contact is formed between the contact surfaces of the cover element and the heat dissipation points of the printed circuit board. Welding also achieves a seal for the assembly.According to an alternative preferred embodiment, the cover element and the base part can be connected to each other by axial or radial screwing in the position in which a thermal contact is formed between the contact surfaces of the cover element and the heat dissipation points of the circuit board.

[0017] It is advantageous if a circumferential radial seal is provided on or in at least one of the guide profiles, which is designed to seal the assembly to the outside.

[0018] Preferably, the component is an electrical or electronic component. More preferably, the component is a power electronics component. Even more preferably, the component is an inverter for an electric motor.

[0019] According to a preferred embodiment, at least one electrical connection can be made to the circuit board before the cover element is placed on the base part. Preferably, stator wires of an electric motor are connected to the circuit board. Due to the direct electrical contact, interfaces are reduced, and the number of components is also decreased.

[0020] It is advantageous if the base part is designed as part of a housing. Furthermore, it is advantageous if the base part is designed as part of a motor housing. Brief description of the drawings

[0021] The embodiments are explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 an electric motor with an inverter; Fig. 2 a power electronic component according to the state of the art; Fig. 3 a further power electronic component in accordance with the state of the art; Fig. 4 the assembly of a component unit according to an embodiment of the present invention; Fig. 5. The fixing of the lid element relative to the base part by circumferential welding; Fig. 6. The fixing of the lid element relative to the base part by screwing; Fig. 7 an electronics pre-assembly unit with pre-assembled support elements; Fig. 8 the installation of the in Fig. The 7 electronic pre-assembly modules shown are combined into a single unit. Description of embodiments

[0022] The present invention relates to a component, in particular a power electronics component, in which the heat generated during operation is dissipated by a heat sink. An example of such a component is shown in Fig. Figure 1 shows an inverter 1 mounted directly on an electric motor 2. The inverter 1 is designed to provide the currents required to operate the electric motor 2. The inverter 1 comprises a base part 3, which is designed as part of the motor housing, and a cover element 4, which serves as a heat sink for the power electronics. The present invention is not limited to the inventions described in Figure 1. Fig. The invention is limited to the inverter shown in Figure 1. Rather, it can be used for any type of electrical or electronic component.

[0023] Typically, printed circuit boards requiring high heat dissipation are screwed directly to the heatsink to allow for tight tolerances and thus a thin layer of thermal paste. Fig. Figure 2 shows such a prior art solution. The printed circuit board 5 with the heat-conducting elements 6 arranged on it is inserted into the cover element 4 in the direction of arrow 7 and screwed to the cover element 4. The cover element 4 is designed as a heat sink and dissipates the heat generated by the power electronics.

[0024] To reduce the number of components in the overall design and / or to minimize interfaces, a higher level of integration of the electronics into the motor should be pursued. This means that functional elements are used for both the motor and the electronics, e.g., the housing function.

[0025] If the architecture still provides for the top element to function as a heat sink (e.g., in air-cooled systems), it is particularly advantageous if the electronics can be attached to the base before the top element is fitted. Such a prior art solution is described in Fig. Figure 3 illustrates this. In this prior art embodiment, the circuit boards 8 and 9 are screwed to the base part 10 beforehand. In this assembly sequence, conductor connections, such as the stator wires 11, can be connected directly to the electronics before the cover element 12 is attached. The cover element 12 is then placed onto the base part 10. A layer 13 of thermal paste is provided between the circuit board 8 and the cover element 12 to dissipate the heat generated to the cover element 12.

[0026] In this setup, the electronics are typically screwed to the base part 10 first—in this example, the motor housing—and then the cover element 12 is placed onto the base part 10. This results in a long tolerance chain for the thermal paste, with the thickness tolerance of the circuit board 8 (approximately 0.38 mm) being the largest contributor. Since the thickness tolerance of the circuit board 8 is included in this tolerance chain, the target tolerance of the thermal paste layer thickness of 0.25 mm ± 0.05 mm cannot be achieved.

[0027] According to the embodiments of the present invention, a particularly cost-effective and low-interface assembly sequence is enabled, in which the printed circuit board(s) are first mounted in the base part, in this example in the motor housing, and then the heat sink is added, while simultaneously allowing for a thin layer of thermal paste. For this purpose, the architecture is modified so that the thickness tolerance of the printed circuit board can be compensated for during assembly.

[0028] In Fig. Figure 4 shows an embodiment of the present invention. In this embodiment, printed circuit boards 14 and 15 are first mounted on corresponding support points in a base part 16, the support points being individual domes 17, 18 and / or a circumferential rim 19. The printed circuit boards 14, 15 are inserted into the base part 16 such that the components 20 are located on the side of the printed circuit board 14 facing the base part 16. The printed circuit boards 14, 15 can be placed on the base part 16 or additionally screwed in place. To dissipate the heat generated during operation, heat dissipation points are provided on the side of the printed circuit boards facing away from the base part 16. These heat dissipation points comprise several cylindrical thermal conductivity elements 21 on the side of the printed circuit board 14 facing away from the base part 16. Thermal paste 22 is then applied to the heat dissipation points of the printed circuit board 14, and then the cover element 23 is placed on top.For this purpose, the cover element 23, which is designed as a heat sink, is placed onto the base part 16 in the direction of arrow 24. The cover element 23 and the base part 16 have a guide device 25 to guide the cover element 23 towards the base part 16. The guide device 25 comprises a first guide profile that completely or partially surrounds the edge of the cover element 23. Furthermore, the guide device 25 comprises a second guide profile that completely or partially surrounds the edge of the base part 16. When placed onto the base part 16, the first guide profile of the cover element 23 engages with the second guide profile of the base part 16, and the cover element 23 is guided and movable towards the base part 16.

[0029] During the pressing of the cover element 23, the thermal paste 22 is displaced in the resulting gap and distributed as completely as possible. The corresponding counterforce is transmitted via the circuit board 14 to the contact surfaces of the base part 16, for example, to the contact surfaces in the motor. For this purpose, contact surfaces of the cover element 23 are pressed against heat dissipation points on the side of the circuit board 14 facing away from the base part 16. At the end of the pressing process, the cover element 23 is pressed into contact with the circuit board 14 at defined points to establish a controlled gap for the thermal paste 22, without the thickness tolerance of the circuit board 14 entering the tolerance chain.

[0030] The cover element 23 is then to be fixed in the present position. For this purpose, a fixing device 26 is provided to fix the cover element 23 relative to the base part 16 in a position where thermal contact is formed between the contact surfaces of the cover element 23 and the heat dissipation points of the printed circuit board 14. This fixing can be achieved, for example, by circumferential welding, such as laser welding, which has the additional benefit of simultaneously sealing the assembly. Fig. Figure 5 shows an embodiment in which the base part 16 and the cover element 23 are joined by circumferential welding. Fig. Figure 5 shows the circuit board 14 with the components 20 and the circuit board 15. On the side of the circuit board 14 facing the cover element 23, the cylindrical thermal conductivity elements 21 are visible, with a thermal connection to the cover element 23 being established via a layer of thermal paste 22. Furthermore, in Fig. 5 as a fixing device 26 a circumferential welding is provided, with which a sealing of the assembly is achieved at the same time.

[0031] Alternatively, screws, for example axial or radial screws, could be used to connect the cover element to the base part. This alternative fixing method using screws is described in Fig. 6 shown. Fig. Figure 6 shows the base part 16 and the cover element 23 mounted on it, wherein the circuit board 14 with the components 20 and the circuit board 15 are inserted in the base part 16. The cylindrical thermal conductivity elements 21 are also shown, which are thermally connected to the cover element 23 via a layer of thermal paste 22. In the embodiment of Fig. Six screw connections are provided as fixing devices 26 for fixing the cover element 23 relative to the base part 16. A radial seal 27 compensates for the resulting tolerance in the gap between the cover element 23 and the base part 16. This radial seal 27 seals the assembly to the outside.

[0032] In the Fig. In embodiments 4 to 6, the printed circuit board 14 is installed with contact from both the base part 16 and the cover element 23. This allows the assembly sequence to be adapted so that electrical contact can be made after the printed circuit boards are inserted, and only then is the product closed by attaching the heat sink. This enables direct and therefore interface-free electrical contact between the printed circuit board and the stator wires, as well as external heat dissipation (e.g., for air cooling). Because the heat sink is placed on the printed circuit board, the thickness tolerance of the printed circuit board with respect to the thickness of the thermal paste is eliminated.

[0033] Another, particularly advantageous embodiment relates to the use of multiple printed circuit boards. Instead of using continuous domes, the individual printed circuit boards can be connected with support elements. Such an embodiment is described in the Fig. 7 and Fig. 8 shown, where in Fig. Figure 7 shows an electronics pre-assembly 28 with pre-assembled support elements. The electronics pre-assembly 28 comprises a first printed circuit board 29 on which several thermal conductivity elements 30 are arranged, and a second printed circuit board 31, wherein the first printed circuit board 29 and the second printed circuit board 31 are connected to each other by means of the support elements 32.

[0034] In Fig. Figure 8 shows how the pre-assembled electronics module 28 is installed in the respective assembly. For this purpose, the Fig. The electronic assembly 28 shown in Figure 7, comprising the first circuit board 29, the thermal interface elements 30, the second circuit board 31, and the support elements 32, is inserted as a whole into the base part 33. Thermal paste is then applied to the heat dissipation points of the circuit boards and to the thermal interface elements 30. In the next step, the cover element 34 is placed onto the base part 33 and pressed against it. The cover element 34 and the base part 33 each have a guide 35 to guide the cover element 34 towards the base part 33. This creates a defined layer of thermal paste between the heat dissipation points and the contact surfaces of the cover element 34. In this position, the cover element 34 is fixed relative to the base part 33. The advantage of the design described in the Fig. 7 and Fig. The embodiment shown in Figure 8 is that the Fig.The pre-assembled electronics module 28 shown in Figure 7 can be functionally tested before installation, for example, in the engine. This is particularly important if the engine and electronics are assembled in different factories. Furthermore, less installation space is required because the support surfaces of the two circuit boards 29 and 31 are aligned. The support elements 32 provide transport fixation and also absorb the assembly forces when the cover element 34 is attached.

[0035] The features disclosed in the foregoing description, the claims and the drawings can be important for the realization of the invention in its various embodiments, both individually and in any combination.

Claims

[1] Component, in particular control unit, which comprises: - a housing with a base part (16, 33) and a cover element (23, 34) which is designed as a heat sink or comprises at least one heat sink and has at least one contact surface for heat dissipation, and - a printed circuit board (14, 29) which is arranged in a fixed position inside the housing and has at least one heat dissipation point facing the cover element (23, 34) and provided for heat dissipation, - wherein the base part (16, 33) and the cover element (23, 34) have a guide device (25, 35) for guiding the cover element (23, 34) towards the base part (16, 33), - wherein the cover element (23, 34) placed on the base part (16, 33) is arranged with respect to the base part (16, 33) such that the at least one contact surface of the cover element (23, 34) bears against the at least one heat dissipation point of the circuit board (14, 29), so that thermal contact is established between the at least one contact surface of the cover element (23, 34) and the at least one heat dissipation point of the circuit board (14, 29). [2] Assembly according to claim 1, characterized by that the printed circuit board (14, 29) is arranged on support points (17, 19) of the base part (16, 33) provided for this purpose. [3] Assembly according to claim 1 or claim 2, characterized by that components (20) are attached to the side of the circuit board (14, 29) facing the base part (16, 33), wherein the heat dissipation points are designed to dissipate the heat generated by the components (20). [4] Assembly according to one of claims 1 to 3, characterized by that the structural unit comprises a plurality of printed circuit boards (29, 31) which are connected to one another by means of support elements (32). [5] Assembly according to one of claims 1 to 4, characterized by that the structural unit comprises a plurality of printed circuit boards (29, 31), wherein the printed circuit boards (29, 31) can be connected to a pre-assembly unit (28) by means of support elements (32) before being inserted into the base part (16, 33). [6] Assembly according to one of claims 1 to 5, characterized by that a thermal contact is established between the at least one contact surface of the cover element (23, 34) and the at least one heat dissipation point of the printed circuit board (14, 29) via a layer (22) of thermally conductive paste. [7] Assembly according to one of claims 1 to 6, characterized byin that the cover element (23, 34) has a first guide profile which runs completely or partially around the edge of the cover element (23, 34) and the base part (16, 33) has a second guide profile which runs completely or partially around the edge of the base part (16, 33), wherein the first guide profile of the cover element (23, 34) engages with the second guide profile of the base part (16, 33) when placed on the base part (16, 33) and the cover element (23, 34) is guided and movable in the direction of the base part (16, 33). [8] Assembly according to one of claims 1 to 7, characterized by in that the assembly comprises a fixing device (26) for fixing the cover element (23, 34) relative to the base part (16, 33) in a position in which a thermal contact is formed between the contact surfaces of the cover element (23, 34) and the heat dissipation points of the circuit board (14, 29). [9] Assembly according to claim 8, characterized bythat the cover element (23, 34) and the base part (16, 33) can be welded together in the position in which a thermal contact is formed between the contact surfaces of the cover element (23, 34) and the heat dissipation points of the circuit board (14, 29). [10] Assembly according to claim 8 or claim 9, characterized by that the cover element (23, 34) and the base part (16, 33) can be connected to one another by axial or radial screwing in the position in which a thermal contact is formed between the contact surfaces of the cover element (23, 34) and the heat dissipation points of the printed circuit board (14, 29). [11] Assembly according to one of claims 1 to 10, characterized by that the unit is a power electronics unit. [12] Assembly according to one of claims 1 to 11, characterized by that the unit is an inverter for an electric motor. [13] Assembly according to one of claims 1 to 12, characterized by that before placing the cover element (23, 34) on the base part (16, 33) at least one electrical supply line can be connected to the circuit board (14, 29). [14] Assembly according to one of claims 1 to 13, characterized by that the base part (16, 33) is designed as part of a motor housing. [15] Method for assembling a structural unit starting from a base part (16, 33), a printed circuit board (14, 29) and a cover element (23, 34) which is designed as a heat sink or comprises at least one heat sink, the method comprising the following steps: - Applying the printed circuit board (14, 29) to support points (17, 19) of the base part (16, 33) provided for this purpose, - placing the cover element (23, 34) on the base part (16, 33) with the circuit board (14, 29), wherein the cover element (23, 34) engages with the base part (16, 33) when placed on the base part (16, 33) and is guided and movable in the direction of the base part (16, 33), - pressing the cover element (23, 34) placed on the base part (16, 33) onto the base part (16, 33), wherein at least one contact surface of the cover element (23, 34) is pressed against the at least one heat dissipation point of the circuit board (14, 29) in such a way that a thermal contact is established between the at least one contact surface of the cover element (23, 34) and the at least one heat dissipation point of the circuit board (14, 29) via a layer (22) of thermally conductive paste, and - in a position in which a thermal contact is formed between the contact surfaces of the cover element (23, 34) and the heat dissipation points of the circuit board (14, 29), fixing the cover element (23, 34) relative to the base part (16, 33).

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