Device with at least one electronic component and method for producing

Abstract

The invention relates to a device (20) with at least one electronic component (29, 30) and at least one housing component (21) made of a plastic material, wherein the electronic component (29, 30) is connected to a metallic heat sink (35) for dissipating heat from the electronic component (29, 30), wherein the heat sink (35) has a surface region (44, 45, 46) with a surface structure and wherein the heat sink (35) is connected to the at least one housing component (21) in a region of the surface structure, in particular in a force-fitting and / or form-fitting manner.

Description

State of the art

[0001] DE 10 2016 209 950 A1 already discloses a method for joining two components, in which a joining area of ​​the component surfaces to be joined is heated by means of a radiation source, wherein the first component is made of plastic and the second component is made of a metal. The heating enables liquefied plastic material to penetrate structures of the metal surface, resulting in an intimate interlock between the plastic material of the first component and the surface structure of the second metallic component. This creates a connection that also enables the connection to be media-tight. The connection is designed, in particular, to be force-fitting and / or form-fitting. Disclosure of the inventionAdvantages of the invention

[0002] The device with the features of the independent claim utilizes a positive and non-positive connection between a metallic component and a plastic component to enable the dissipation of waste heat generated during operation of an electronic component. This utilizes the fact that the connection of a plastic material to a structured metal surface not only represents a robust non-positive connection, but also enables good heat transfer from the metal to the plastic material by avoiding a thermally insulating layer of air. Heat transfer takes place effectively and evenly in the region of the structured surface, so that the heat absorbed by the heat sink from the electronic component can be effectively transferred to the housing component made of the plastic material via a large-area heat spread.This makes it possible to construct an outer housing of a device entirely or at least partially from a plastic material, while the heat generated during operation of electronic components inside the device is conducted and spread via the heat sink and can be dissipated via the positive connection and the housing. The use of plastic for the housing component thus allows for the corresponding advantages to be exploited, such as a wide range of spatial design options, electrical insulation, and low weight, while still ensuring good heat dissipation.

[0003] Further advantages arise from the dependent claims. For example, it is advantageous to create a secure connection between the heat sink and the housing component using a joining process or an injection molding process, including special processes such as injection-compression molding. This ensures that the material of the housing component can blend seamlessly into the structures of the surface area of ​​the heat sink, resulting in the best possible surface reproduction without air-filled defects / gaps and thus the greatest possible heat conduction at the transition between the metal and the plastic. At the same time, a stable and tight connection is enabled.

[0004] Furthermore, it is advantageous to design the housing component as an injection-molded part, as this allows for a wide variety of shapes and ease of manufacture. This allows the device to be easily adapted to different installation locations by selecting the appropriate injection mold. Thermoplastics with low melt viscosity are particularly preferred as the plastic material to enable good filling behavior of the recesses with a high aspect ratio. Furthermore, plastics with low shrinkage values ​​are preferred to reduce the risk of shrinkage-related vacuoles during the cooling process.

[0005] It is further advantageous for the housing component to have an opening to the exterior of the device such that a surface of the heat sink is accessible for airflow through the opening. In addition to heat conduction through or with the plastic housing component, additional heat can be dissipated through the direct airflow to the heat sink. Due to the integral connection between the heat sink and the housing component, no additional seal is required, since the connection between the heat sink and the housing component is already sealed by a suitable choice of plastic material and the type and geometry of the structuring, as well as by joining process control.

[0006] A particularly effective cooling effect is achieved when the heat sink has cooling fins in the area of ​​the opening, thus increasing the surface area of ​​the heat sink facing the airflow. The arrangement of the cooling fins within the opening allows the cooling fins to not protrude beyond the opening and thus from the device, thus enabling a compact design of the device.

[0007] Furthermore, it is advantageous that the housing component and the heat sink are connected to one another in a sealing manner to seal an interior of the device from an exterior space, since this eliminates the need for additional seals and the connection between the housing component and the heat sink is already designed to seal the interior space.

[0008] Furthermore, in another embodiment, it is advantageous to completely cover the heat sink with the housing component from an exterior of the device. This prevents or at least reduces external contact of metal with an exterior of the device, while the good thermal connection between the heat sink and the housing component still allows heat from the operation of the electronic component to be safely dissipated to the exterior of the device.

[0009] It is also advantageous for the electronic component to be arranged on a circuit board, which is located on a side of the electronic device facing away from the heat sink. Such an arrangement on a circuit board allows the electronic component to be easily supplied with electrical power, and data can be easily transferred from the circuit board. Thermal cooling is achieved via the heat sink located opposite the circuit board, thus enabling a space-saving design.

[0010] Furthermore, it is advantageous for electrical contacts to the circuit board or electronic component to be embedded in the housing component. This allows for easy implementation of feedthroughs to connectors on the outside. Furthermore, it is also possible to supply electrical current to the circuit board without the need for additional insulation, since the plastic material of the housing component can already perform this insulating function.

[0011] Furthermore, it is advantageous for the heat sink to be shaped such that it has both a region with a structure parallel to a surface of the housing component and a surface parallel to the electronic component, as well as an intermediate region that connects the two surface regions. This intermediate region enables heat conduction from the interior of the device to the exterior of the housing component. Furthermore, appropriate shaping of the heat sink can additionally ensure stability of the device within, in that a force acting on the housing component from the outside can be dissipated to stable structures in the housing interior, such as internal rib structures or the circuit board.

[0012] It is further advantageous that the housing component covers the heat sink in such a way that a heat flow from the electronic component to an exterior of the device via the heat sink and the housing component is enabled, since in this way the heat can be efficiently dissipated to the outside.

[0013] Corresponding advantages also arise for a method for producing a device in which the housing component is made of a plastic material and connected to a metallic heat sink which has a structuring in a surface region, so that a coherent connection between the structured surface region and the housing component is enabled.

[0014] Furthermore, it is advantageous for the plastic material of the housing component to be melted in such a way that the plastic material engages with the structures of the structured surface area of ​​the heat sink to achieve a secure connection. This also permanently prevents corrosive infiltration in the joining interface, particularly as a result of thermal and / or climatic aging processes.

[0015] Furthermore, it is advantageous to produce the housing components in an injection molding process, wherein the heat sink is inserted wholly or partially into the injection mold and is heated at least in the overmolding area for the duration of the overflow to near the crystallite melting temperature of the plastic used in the injection mold, so that at least part of the heat sink is overmolded with the plastic material of the housing component.

[0016] By connecting the heat sink to the electronic component, an advantageous thermal connection to the housing component is made possible, wherein in one embodiment a thermally conductive material can advantageously be arranged between the heat sink and the electronic component. drawing

[0017] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. Fig. 1 a cross-section of a metal-plastic connection for connecting the heat sink to the housing component, Fig. 2 shows a first embodiment of a device with a housing component and a heat sink in a cross-sectional view, Fig. 3 the arrangement according to the Fig. 2 according to a supervision, Fig. 4 and Fig. 5 further embodiments of a device with a heat sink and a housing component in a sectional view. Embodiments of the invention

[0018] In the Fig. 1 shows an example of a connection between a housing component 11, for example made of a thermoplastic material, in particular polyamide, PBT, PPS or polypropylene, and a metallic heat sink 10. The heat sink 10 has a surface structuring 12 which enlarges its surface area. The surface structuring 12 can be implemented, for example, as laser structuring, with which structures in the range of 10 to 50 micrometers are created on the surface of the metallic heat sink. This creates moss-like, cauliflower-like or coral-like structures which create a very roughened surface, but in particular possibly also undercuts. In another embodiment, the surface can also be etched using an electrochemical process. Aluminum or copper, for example, can be used as the metallic material for the heat sink 10.

[0019] By adapting the structuring processes, the desired surface structuring can be adapted, particularly empirically, to a specific application. In a comparison of correspondingly illustrated metal-plastic transitions with thermal contact riveting (so-called heat staking), significantly improved heat transfers with up to 40 percent better heat conduction were experimentally demonstrated, depending on the positioning of the measuring points between a heat sink and a plastic housing. At the same time, it was determined that thermal aging due to thermal shock loading during thermal joining of the heat sink 10 and the housing components 11 does not lead to a deterioration of the connection properties, such as through delamination or gap formation.

[0020] In the Fig. 2 shows a sectional view of a device 20 having a housing consisting of a first housing component 21 and a housing component 22. The second housing component 22 acts as a cover to close the first housing component 21, which forms an interior space 23. The cover 22 seals the interior space 23 from an exterior space 24.

[0021] The first housing component 21 and preferably also the cover 22 are formed from a plastic material, in particular from a thermoplastic. On an outer side 25 of the first housing component 21, a plug 26 is formed integrally with the first housing component. An electrical contact 27 is provided inside the plug to accommodate a suitable connection plug.

[0022] In the interior 23, a printed circuit board 28 is arranged, on which, in the embodiment shown here, a first electronic component 29 and a second electronic component 30 are arranged, which are connected to the Fig. 2, not shown, are electrically contacted on the printed circuit board 28. The printed circuit board 28, in turn, is connected to the electrical contact 27 in the plug 26 via an electrical connection contact 31, wherein an electrical line 32 is embedded in the plastic material of the first housing component 21. In the exemplary embodiment shown here, the printed circuit board 28 is latched to a thickened portion 33 of the connection contact 31. The first housing component 21 has support elements 34 that support and stabilize the printed circuit board 28 and the connection contact 31.

[0023] The first and second electronic components 29, 30 are thermally connected to a heat sink 35, so that the heat from the electronic components is dissipated to the heat sink 35. For this purpose, the electronic components can be in direct pressure contact with the heat sink 35. In the exemplary embodiment shown here, contact is made via a thermal interface material, such as a thermal paste, which is arranged between the heat sink 35 and the electronic components 29, 30.

[0024] The heat sink 35 is designed as a heat-conducting plate, for example, made of aluminum, copper, or another suitable metal. The heat sink has a first region 38 parallel to a surface 39 of the second electronic component 30 and a second region 40 parallel to a first surface 41 of the first electronic component 29. The circuit board 28 and thus also the electronic components 29, 30 are arranged at a distance 42 from a surface 43 of the first housing component 21.

[0025] The heat sink 35 is designed in a quasi-meandering manner such that it first contacts the surface 43 of the first housing component 21 in a first contact region 44, then bridges the distance 42 to the second electronic component 30, which is then followed by the first region 38 parallel to the surface 39 of the second electronic component, the heat sink subsequently being shaped such that it bridges the distance 42 again. The heat sink now forms a second contact region 45, which contacts the first housing component 21. Following this, the heat sink is shaped such that it once again bridges the distance 42 to the first electronic component 29 and leads to the second region on the first electronic component 29. The heat sink 35 is then shaped such that it once again bridges the distance 42 and reaches the surface 43 of the first housing component 21 in a third contact region 46.

[0026] In the contact areas 44, 45, 46, the Fig. 1 between the metallic heat sink 35 and the plastic material of the first housing component 21. This contact can be represented, for example, by first creating a surface structure in the contact areas 44, 45, 46 of the heat sink 35 using a laser or a chemical structuring process. Subsequently, a surface 43 of the first housing component 21 is heated in those areas where the heat sink 35 is to be attached, for example by infrared radiation or laser radiation. The heat sink 35 is then pressed onto the surface 43 of the housing component 21 so that a desired metal-plastic connection is created in the contact areas 44, 45, 46, as can be seen from the Fig. 1 was explained.

[0027] In a subsequent work step, the printed circuit board 28 with the electronic component 29, 30 already mounted thereon can be attached to the connection contact 31, whereby the electronic components 29, 30 are brought into thermally conductive connection with the heat sink 35. For mechanical stabilization or to implement additional electrical contacts, a further electrical contact 47 corresponding to the first electrical connection contact 31 can be provided on the first housing component 21 and protruding into the interior 23. This further electrical contact 47 is attached to the circuit board 26 on a side of the first electrical contact facing away from the plug 26. This further electrical contact 47 also engages the plastic material of the first housing component 21.

[0028] In the Fig. 3 is a supervision of the arrangement according to the Fig. 2 without the cover 22. This view clearly shows that, parallel to the first connection contact 31, further connectors 48 can contact the circuit board 28 and are routed to corresponding connections on the connector 26. Likewise, parallel to the further electrical contact 47, a further connector 49 can be arranged on the circuit board 28 on the side of the circuit board facing away from the connector 26 for stabilization purposes.

[0029] The device 20 can be used for any purpose for which an electronic circuit is to be provided, whereby waste heat is generated and dissipated to the outside. For example, this can be a use for any type of control unit, such as engine control units or control units for safety devices in motor vehicles. Data can be introduced into the device 20 for processing via the connector 26, and control data for components outside the control unit can also be read out of the device 20 again, for example via a data bus connection. The data is processed by the electronic components 29, 30, which are designed, for example, as microprocessors or as system-on-chip systems. The waste heat generated in this process is conducted via the heat sink 35 to the first housing component 21. This takes advantage of the fact that the heat sink can conduct the generated heat well.The contact areas 44, 45, 46 also ensure good heat transfer to the material of the first housing component 21, so that the heat can be dissipated to the exterior 24 at those points where the heat sink 35 contacts the first housing component. An air flow surrounding the device 20 or thermal convection can then dissipate the heat. Due to the particularly efficient thermal coupling through the metal-plastic connection, as can be seen from FIG. Fig. 1, this ensures good heat conduction on the one hand, and prevents overheating of the plastic material of the first housing component 21 on the other. The plastic material of the first housing component can effectively protect the electrical components inside the device 20 against external influences such as moisture or dust.

[0030] In the embodiment shown here, contact is made between two electronic components. However, it is also possible to connect only one electronic component or, if necessary, several electronic components or other components that generate waste heat in the interior.

[0031] In the Fig. 4 shows a second embodiment of a device 20', in which a slightly modified first housing component 51 and a modified heat sink 50 are used compared to the first embodiment. The remaining components are similar in the embodiment shown here and are therefore also given the same reference numerals as in the Fig. 2 in the Fig. 4. The heat sink 50 is comparable to the heat sink 35 in the Fig. 2, but has openings 52 on a side facing away from the circuit board 28, for example, slots or round holes made in the surface of the heat sink 50. In the contact areas 54, 55, 56 running parallel to an outer side 53 of the first housing component 51, the heat sink 50 is immersed in the plastic material of the first housing component 51. This is illustrated, for example, by the heat sink 50 being overmolded with the plastic material of the first housing component 51 during an injection molding process. In another embodiment, it is also possible for the plastic material of the first housing component 51 to be heated to a high degree and the heat sink 50 to be pressed into the molten material. The openings 52 facilitate the immersion or overmold.

[0032] The surfaces of the heat sink 50 are preferably on both sides of the surface, but possibly also only on one side according to the Fig. 1, is provided with a structure to ensure optimal bonding to the plastic material of the first housing component 51. By integrating the heat sink 50 into the plastic material of the first housing component 51, heat transfer to the plastic material can be further improved. Furthermore, the connection between the plastic material and the heat sink 50 is mechanically strengthened.

[0033] In the embodiments of the Fig. 2 and the Fig. 4 there is no contact between the outer space 24 and the heat sink 35, 50, so that the device 20 is sealed from the outer space and there is no contact with the metallic heat sink, so that it is also electrically insulated from the outside.

[0034] In the Fig.5 shows an embodiment in the form of a device 20" in which an even better cooling performance is achieved. A heat sink 60 is inserted into an opening 62 of the housing component 61 such that it contacts the outer space 24. The heat sink has cooling fins 65 which face the outer space 24.

[0035] The heat sink 60 contacts the plastic material of the first housing components 61 at an edge 64 of the opening 62. Due to this contact and the fact that the heat sink 60 has no opening, the interior 23 is sealed from the exterior 24. In the embodiment shown here, the heat sink 60 does not protrude beyond the surface 63 of the first housing component 61. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2016 209 950 A1

[0001]

Claims

[1] Device (20) with at least one electronic component (29, 30) and at least one housing component (21) made of a plastic material, wherein the electronic component (29, 30) is connected to a metallic heat sink (35) for dissipating heat from the electronic component (29, 30), wherein the heat sink (35) has a surface region (44, 45, 46) with a surface structuring and wherein the heat sink (35) is connected to the at least one housing component (21), in particular in a force-fitting and / or form-fitting manner, in a region of the surface structuring. [2] Device according to claim 1, characterized by that the coherent connection between the heat sink (35) and the housing component (21) is effected by means of a joining process, in particular by means of thermal direct joining, or an injection molding process. [3] Device according to one of the preceding claims, characterized bythat the housing component (21) is designed as an injection-molded component. [4] Device according to one of the preceding claims, characterized by that the housing component has an opening to the exterior space (24) of the device (20) such that a surface of the heat sink is accessible to an air flow through the opening. [5] Device according to claim 4, characterized by that the heat sink has cooling fins (65) in the area of the opening. [6] Device according to one of claims 4 or 5, characterized by that the housing component (21) and heat sink (35) are connected to one another in a sealing manner to form an interior space (23) of the device relative to an exterior space (24) of the device. [7] Device according to one of claims 1-3, characterized by that the heat sink (35) is completely covered by the housing component (21) with respect to an outer space (24) of the device (20). [8] Device according to one of the preceding claims, characterized by that the electronic component (29, 30) is arranged on a printed circuit board (28) and that the printed circuit board (28) is arranged on a side of the electronic component (29, 30) facing away from the heat sink (35). [9] Device according to one of claims 7-8, characterized by that an electrical line (32) to the circuit board (28) or to the electronic component is embedded in the housing component (21). [10] Device according to one of the preceding claims, characterized bythat the heat sink (35) is shaped such that the heat sink has a region which runs parallel to a surface of the housing component and of the electronic component, and at least one intermediate region which connects the two regions, wherein the intermediate region has an orientation in space which differs from the other two regions and is in particular oriented perpendicular to the other two regions. [11] Device according to one of the preceding claims, characterized by that the housing component (21) covers the heat sink (35) in such a way that a heat flow from the electronic component to an external space (24) of the device (20) runs via the heat sink (35) and the housing component into the external space (24). [12] Method for producing a device, in particular according to one of the preceding claims, wherein a housing component (21) is produced from a plastic material, in particular by an injection molding process, wherein a metallic heat sink (35) is produced, wherein a surface region of the heat sink (35) is structured, wherein the heat sink is integrally connected to the plastic material of the housing component (21) at the structured surface region. [13] Method according to claim 12, characterized by that the plastic material of the housing component (21) is melted in such a way that the plastic material engages in the structures of the structured surface region of the heat sink (35) in order to create the connection between the heat sink (35) and the housing component (21). [14] Method according to claim 12, characterized bythat the housing component is manufactured using an injection molding process and that during the injection molding process the heat sink is partially inserted into the injection molding tool in such a way that part of the heat sink is overmolded with the plastic material of the housing component. [15] Method according to one of claims 12-14, characterized by that the electronic component is connected to the heat sink, in particular by means of an arrangement of a heat-conducting material.

Images