Electronic arrangement

Abstract

The invention relates to an electronic arrangement (10) comprising - an electronic component (2), - a metal plate (4) having two flat sides (4a, 4b) and a circumferential rim (4c), and - a plastic component (6) made of a thermally conductive plastic, wherein - the electronic component (2) is in contact with the metal plate (4), - the plastic component (6) is in contact with at least one of the flat sides (4a, 4b) and with the circumferential edge (4c) of the metal plate (4), and - the plastic component (6) is shaped in such a way that it has cooling fins (8).

Description

[0001] The present invention relates to an electronic arrangement, a switching device and a method.

[0002] The waste heat from electronic components must be dissipated to prevent overheating and thus damage. The problem of adequate heat dissipation from electronic components becomes particularly critical when the electronic components are installed in confined spaces and when the current is high, such as the starting current of a motor.

[0003] There is therefore a need for an electronic arrangement that ensures that the heat loss of an electronic component can be dissipated to a sufficient extent.

[0004] This object is achieved according to the invention by an electronic arrangement having the features specified in claim 1, a switching device having the features specified in claim 9 and a method having the features specified in claim 10.

[0005] The electronic arrangement according to the invention comprises at least one electronic component. An electronic component comprises one or more electronic components. In electrical engineering and electronics, a component, or electronic component for short, is the smallest, non-divisible unit in a circuit (DIN 40150:1979-10 Terms for the classification of functional and structural units), e.g., a resistor. An electronic component can be a passive electronic component, such as a resistor, a coil, or a capacitor. An electronic component can also be an active electronic component, such as a transistor (IGBT, FET, MOSFET, etc.), a diode, a rectifier, a processor / IC (= integrated circuit), or an LED. An electronic component can also be a power electronics component. Electronic components can be, for example, diacs, triacs, transistors, MOSFETs, IGBTs, thyristors, diodes, capacitors, etc.in power electronics, as well as components in control electronics such as controllers, voltage regulators, resistors, coils, etc. An electronic component can in particular be a power semiconductor or a power semiconductor module.

[0006] The electronic assembly according to the invention comprises at least one metal plate, preferably made of a metal with good thermal conductivity, which is easy to process and yet affordable. Due to its shape, the metal plate, also referred to as a "metal inlay," has two preferably parallel flat sides and a peripheral edge, with the edge connecting the two flat sides. The metal plate can have any contour, e.g., square, rectangular, round, oval, or any other suitable shape. The position and size of the metal inlay are variable; depending on the application of the electronic assembly or the waste heat output of the electronic component, one or more metal inlays can be arranged only at the main heat sources of the electronic component to specifically spread the waste heat, or a metal plate can be arranged across the entire electronic component – ​​here, the costs and benefits must be weighed against each other.

[0007] The electronic assembly according to the invention comprises at least one plastic component made of a thermally conductive plastic. The term "thermally conductive plastic" encompasses plastics whose thermal conductivity is greater than 0.4 W / (mK). Conventional plastics, e.g., polycarbonate, are considered "non-thermally conductive" plastics according to the definition given here; they are characterized by good thermal insulation, with thermal conductivity generally in the range of 0.1 to 0.4 W / mK. A "thermally conductive" plastic, on the other hand, has a thermal conductivity that exceeds that of conventional, non-thermally conductive plastics.

[0008] Preferably, the thermal conductivity of a thermally conductive plastic is more than 1 W / (m K), preferably more than 5 W / (m K), more preferably more than 8 W / (m K).

[0009] The electronic assembly according to the invention is characterized in that the electronic component rests against the metal plate. Insulating intermediate layers, such as air layers, are avoided to ensure the best possible heat transfer from the heat-generating electronic component to the metal plate. A thermally conductive paste can be arranged between the adjacent surfaces of the electronic component and the metal plate. It is also possible for the electronic component and the metal plate to be pressed together by a mechanical connecting element, such as a screw connection.

[0010] The electronic assembly according to the invention is further characterized in that the plastic component rests against at least one of the flat sides and the peripheral edge of the metal plate. Insulating intermediate layers, such as air layers, are avoided to ensure the best possible heat transfer from the heat-generating electronic component to the metal plate. According to the invention, close contact between the plastic component and the metal plate, which promotes heat transfer, is achieved by pouring or injection-molding a liquid, thermally conductive plastic onto at least one of the flat sides and the peripheral edge of the metal plate.

[0011] The electronic assembly according to the invention is further characterized in that the plastic component is shaped to include cooling fins. According to the invention, the plastic component is formed with cooling fins by molding a liquid thermally conductive plastic before it hardens, for example, using a mold, to form at least one cooling fin, which is integrally formed with the plastic component once the liquid thermally conductive plastic has hardened.

[0012] According to the invention, the object is also achieved by a switching device comprising an electronic arrangement according to the invention. The term "switching device" encompasses switching devices, e.g., a relay, and protective devices, e.g., a circuit breaker.

[0013] The object is further achieved according to the invention by a method for producing an electronic assembly according to the invention. The electronic component is placed against the metal plate, and the plastic component is formed by pouring or injection-molding a liquid thermally conductive plastic onto at least one flat side and the peripheral edge of the metal plate. The liquid thermally conductive plastic is shaped such that, after solidification, it forms cooling fins on the plastic component.

[0014] The invention is based on the idea that encasing an electronic component with thermally conductive plastic and a metal plate for heat dissipation across the plastic casing significantly improves heat dissipation from the electronic component. To better distribute the waste heat from the electronic component, a metal plate is embossed into the plastic (metal inlay) at the main heat sources of the electronic component. Metal has excellent heat dissipation and distributes the waste heat across the plastic heat sink. The encapsulated metal plate achieves optimal heat transfer (no air insulation).

[0015] Advantageous embodiments and further developments of the invention are specified in the dependent claims.

[0016] According to a preferred embodiment of the invention, the electronic component is designed as a printed circuit board equipped with heat-dissipating electronic components, and the electronic components are embedded in the plastic component. Encapsulating or embedding electronic components in thermally conductive plastic achieves electrical insulation and heat dissipation. Embedding the electronic components in the plastic component made of thermally conductive plastic significantly improves heat dissipation from the electronic components.

[0017] According to a preferred embodiment of the invention, the electronics assembly is encased in a separate housing. This housing can be made of any material, typically a plastic, whether thermally conductive or not.

[0018] According to a preferred embodiment of the invention, the cooling fins are shaped so that an airflow generated by a fan sweeps along the cooling fins. This forced convection significantly improves heat dissipation from the electronic components.

[0019] According to a preferred embodiment of the invention, the cooling fins are shaped so that an airflow generated by a fan sweeps along the cooling fins and is deflected at one end of the cooling fins. This forced convection significantly improves heat dissipation from the electronic components. It is therefore possible to adjust the airflow using the cooling fins. By deflecting the airflow, the heated airflow can be effectively directed out of the housing, thus significantly improving heat dissipation from the electronic components.

[0020] According to a preferred embodiment of the invention, the plastic component is shaped to form a housing that encloses the electronic component and the metal plate. It is advantageous that not only the cooling fins but also the housing are made of the thermally conductive plastic: The one-piece plastic component, which has cooling fins and forms a housing, enables a significant improvement in heat dissipation from the electronic components.

[0021] Thanks to the thermally conductive plastic and direct casting, the entire housing acts as a cooling element. The improved heat dissipation of the new housing material, namely the thermally conductive plastic, allows for housings with a significantly smaller installation space than those made with conventional materials (non-thermally conductive plastic).

[0022] According to a preferred embodiment of the invention, the electronic component is connected to the metal plate by screw connections. This provides the advantage of achieving close contact between the electronic component and the metal plate, significantly improving heat dissipation from the electronic components. Insulating air layers between the electronic component and the metal plate are largely avoided or minimized by the screw connections.

[0023] According to a preferred embodiment of the invention, the metal plate is made of aluminum or copper. Both are good heat conductors, easy to process, and yet affordable metals.

[0024] According to a preferred embodiment of the method, the metal plate is first fed into an injection mold as an insert and overmolded with the thermally conductive plastic during an injection molding process to create a plastic-metal hybrid part. The electronic component is then fixed to a flat side of the metal plate.

[0025] According to a preferred embodiment of the method, the electronic component is fixed to the flat side of the metal plate by means of a screw connection.

[0026] In the following, the invention is explained using several embodiments with the aid of the accompanying drawings. Each drawing is schematic and not to scale. Fig. 1 shows a first embodiment of the electronic arrangement according to the invention; Fig. 2 shows a second embodiment of the electronic arrangement according to the invention; Fig. 3 a known electronic arrangement; Fig. 4 shows a third embodiment of the electronic arrangement according to the invention; Fig. 5 an oblique view of the electronic arrangement of Fig. 4; Fig. 6 a fourth embodiment of the electronic arrangement according to the invention; Fig. 7 an oblique view of the electronic arrangement of Fig. 6; Fig. 8 shows a fifth embodiment of the electronic arrangement according to the invention; Fig. 9 an oblique view of the electronic arrangement of Fig. 8; Fig. 10 a switching device.

[0027] Fig. 1 shows a first embodiment of the electronic assembly 10 according to the invention in section. The electronic assembly 10 comprises an electronic component 2, a metal plate 4, and a plastic component 6 made of a thermally conductive plastic. The cuboid-shaped metal plate 4 has two flat sides, namely an upper flat side 4a and a lower flat side 4b, as well as a peripheral edge 4c that connects the two flat sides 4a, 4b. The electronic component 2 rests against the upper flat side 4a of the metal plate 4 and is held there by screw connections 16 that press the electronic component 2 against the upper flat side 4a of the metal plate 4. The pressing takes place in such a way that no insulating air layer can form between the electronic component 2 and the metal plate 4.

[0028] The plastic component 6 rests against the entire surface of the lower flat side 4b of the metal plate 4, against the entire surface of the circumferential edge 4c of the metal plate 4, and against part of the surface of the upper flat side 4a of the metal plate 4. The plastic component 6 also rests against part of the electronic component 2. The plastic component 6 is shaped to form a housing 12 that encloses the electronic component 2 and the metal plate 4 and encloses an air space 14 above the electronic component 2 and the metal plate 4. The plastic component 6 also has cooling fins 8 that project downward from the underside 18 of the housing 12, which covers the lower flat side 4b of the metal plate 4.

[0029] The electronic assembly 10 is manufactured by placing the electronic component 2 onto the upper flat side 4a of the metal plate 4 and securing it to the metal plate 4 using screw connections 16. The plastic component 6 is then molded by pouring or injection-molding a liquid, thermally conductive plastic onto the lower flat side 4b, the edge 4c, and a portion of the upper flat side 4a of the metal plate, as well as onto a portion of the electronic component 2. The liquid, thermally conductive plastic is molded such that, after solidification, it forms cooling fins on the plastic component 6 and a housing 12 enclosing the electronic component 2 and the metal plate 4.

[0030] It is possible that the metal plate is first fed into an injection molding tool as an insert and then overmolded with the heat-conducting plastic in an injection molding process to create a plastic-metal hybrid part.

[0031] The electronic component is then fixed to a flat side of the metal plate, preferably using a screw connection.

[0032] Fig. Figure 2 shows a second embodiment of the electronic assembly 10 according to the invention in section. This embodiment is almost identical to that shown in Fig. 1, with the difference that the plastic component 6 made of thermally conductive plastic only rests against the entire surface of the lower flat side 4b of the metal plate 4 and the entire surface of the peripheral edge 4c of the metal plate 4. In contrast, the surface of the upper flat side 4a of the metal plate 4 and the electronic component 2 are not covered by the plastic component 6.

[0033] The skilled person can realize any number of further designs by covering the edge 4c of the metal plate 4, the upper flat side 4a of the metal plate 4, and the electronic component 2 with the plastic component 6 at various degrees of coverage. By selecting the degree of coverage, the skilled person can control the heat dissipation from the electronic component 2.

[0034] In the Fig. 1 and Fig. In the embodiments shown in Figure 2, the housings 12 do not have any ventilation openings. Therefore, these embodiments are suitable for protection class IP65. A product with protection class IP65 has complete contact protection: Dust cannot penetrate and it is protected against water jets from any direction. With protection class IP65, no ventilation openings are permitted, and accordingly, no fans can be used. Heat cannot be dissipated either through natural or forced convection.

[0035] Fig. Figure 3 shows a known electronic assembly in section. An electronic component 2 is designed as a printed circuit board (PCB) 22 equipped with heat-dissipating electronic components 28. The electronic components 28 are arranged on both flat sides of the printed circuit board 22 extending in the xz plane.

[0036] The electronic components 28 are passive electronic components and active electronic components, including power semiconductors and power semiconductor modules 29. A metallic heat sink 20 made of an extruded aluminum profile is arranged on the flat sides of the power semiconductor modules 29 facing away from the circuit board 22, which have the greatest extent in the y-direction, i.e., protrude furthest perpendicularly from the circuit board. The heat sink 20 is designed as a metal plate 4, which carries cooling fins 8 on the flat side facing away from the power semiconductor module 29.

[0037] The electronics assembly also includes a housing 12, which encloses the electronic component 2 and the heat sink 20 and two air spaces 14 on both sides of the circuit board 22, above and below the electronic components 2 and the metal plates 4. The housing has ventilation slots 26 in a housing wall facing in the positive y-direction, which serve to convectively dissipate heat from the electronic component 2.

[0038] Due to the fact that the metallic heat sink 20 is electrically conductive, a safety distance 24 must be maintained between the heat sink 20 and the ventilation slots 26 due to clearance and creepage distances specified by standards. This is intended to ensure that a person who is in the area of ​​the device openings formed by the ventilation slots 26, e.g., reaching into the ventilation slots 26 with their hand, is not endangered by an electrical flashover.

[0039] Fig. Figure 4 shows a third embodiment of the electronic arrangement according to the invention in section. This electronic arrangement according to the invention differs from the one shown in Fig. The known electronic arrangement shown in Figure 3 is characterized in that the electronic components of the electronic component 2 arranged on the circuit board 22 are covered by a plastic component 6 formed from a thermally conductive plastic. A metal plate 4 made of copper is arranged on each of the flat sides of the power semiconductor modules 29 facing away from the circuit board 22. These metal plates 4 are also encased in the plastic component 6. The plastic component 6 also forms cooling fins 8, which protrude along the y-axis in the directions facing away from the circuit board 22.

[0040] Due to the fact that the cooling fins 8, formed from a thermally conductive plastic, are electrically non-conductive, no safety distance 24 needs to be maintained between the cooling fins 8 and the ventilation slots 26. Thus, the housing can be made smaller and the air space 14 can be better utilized.

[0041] Fig. 5 shows an oblique view of the electronic arrangement of Fig. 4. This shows that the metal plates 4 intended for heat dissipation, which lie in the xz plane, are cuboid-shaped. The cooling fins 8 run in the z-direction.

[0042] Fig. 6 and Fig. 7 show a fourth embodiment of the electronic arrangement according to the invention, wherein Fig. 6 a cut and Fig. 7 is an oblique view of the electronics assembly. In this embodiment, the cooling fins form a grid of individual cooling "towers." This increases the heat-dissipating surface of the cooling fins and improves convection. By making the cooling fins 8 from plastic, manufacturing is significantly easier than with metal; thus, a wide variety of fin shapes can be easily and cost-effectively realized, e.g., using casting or injection molding processes. The shapes of the cooling fins possible in the electronics assembly according to the invention are therefore not as rigidly limited as with conventional extruded heat sinks.

[0043] Fig. 8 and Fig. 9 show a fifth embodiment of the electronic arrangement according to the invention, wherein Fig. 8 a cut and Fig. 9 is an oblique view of the electronics assembly. In this embodiment, the cooling fins 8 extend in the x-direction along the longitudinal axis of the circuit board 22, in contrast to the Fig. 4 and Fig. 5, in which the cooling fins 8 extend in the z-direction. A forced air flow 30 emanating from a fan 36 flows along the cooling fins (fan direction) and is deflected outward by 90 degrees at the end of the cooling fins 8 facing away from the fan 36 by a bend in the cooling fins 8 (blow-out direction).

[0044] Fig.10 shows a switching device 100. The switching device 100 has a housing 20 with load current connections 40, 40', which are divided into input terminals 40 and output terminals 40'. The load current line 42 is electrically connected to the load current connections 40, 40' such that the switching device 100 is connected between two ends of the load current line 42. Inside the housing 20, the load current connections 15 are each electrically connected to the electronics assembly 10 by means of a current path 44. List of reference symbols 2 Electronic component 4 metal plate 4a Flat side 4b Flat side 4c surrounding edge 6 Plastic component 8 cooling fins 10 Electronic arrangement 12 housings 14 Airspace 16 screw connection 18 bottom of 12 20 heat sinks 22 printed circuit board, PCB 24 Safety distance 26 Ventilation slot 28 electronic component 29 power semiconductors or power semiconductor modules 30 airflow 32 Fan direction 34 Blow-out direction 36 fans 40 load current connections 40' load current connections 42 load current line 44 Current path 100 switching and / or protective devices

Claims

[1] Electronic arrangement (10), comprising - an electronic component (2), - a metal plate (4) having two flat sides (4a, 4b) and a peripheral edge (4c), and - a plastic component (6) made of a thermally conductive plastic, wherein - the electronic component (2) rests against the metal plate (4), - the plastic component (6) rests against at least one of the flat sides (4a, 4b) and against the peripheral edge (4c) of the metal plate (4), and - the plastic component (6) is shaped so that it has cooling fins (8). [2] Electronic arrangement (10) according to claim 1, wherein the electronic component (2) is designed as a printed circuit board (22) equipped with heat-emitting electronic components (28), and wherein the electronic components (28) are embedded in the plastic component (6). [3] Electronic arrangement (100) according to one of the preceding claims, which is housed in a separate housing (12). [4] Electronic arrangement (100) according to one of the preceding claims, wherein the cooling fins are shaped such that an air flow (30) generated by a fan (36) sweeps along the cooling fins (8). [5] Electronic arrangement (100) according to one of the preceding claims, wherein the cooling fins (8) are shaped such that an air flow (30) generated by a fan (36) sweeps along the cooling fins (8) and is deflected at one end of the cooling fins (8). [6] Electronic assembly (100) according to claim 1, wherein the plastic component (6) is shaped to form a housing (12) which encloses the electronic component (2) and the metal plate (4). [7] Electronic arrangement (100) according to one of the preceding claims, wherein the electronic component (2) is connected to the metal plate (4) by screw connections (16). [8] Electronic assembly (100) according to one of the preceding claims, wherein the metal plate (4) is made of aluminum or copper. [9] Switching device (100) comprising an electronic arrangement (10) according to one of the preceding claims. [10] Method for producing an electronic arrangement (100) according to one of the preceding claims, wherein the electronic component (2) and the metal plate (4) are placed against one another, and the plastic component (6) is formed by pouring or injection-molding a liquid thermally conductive plastic onto at least one flat side (4a, 4b) and onto the peripheral edge (4c) of the metal plate (4), and the liquid thermally conductive plastic is shaped such that, after it has solidified, it forms cooling fins (8) on the plastic component (6). [11] Method according to claim 10, wherein firstly the metal plate (4) is fed as an insert into an injection moulding tool and is encapsulated with the heat-conducting plastic by an injection moulding process, so that a plastic-metal hybrid part is produced, and then the electronic component (2) is fixed to a flat side (4a) of the metal plate (4). [12] Method according to claim 11, wherein the electronic component (2) is fixed to the flat side (4a) of the metal plate (4) by means of a screw connection.

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