Electronic device

Abstract

The invention relates to an electronic device (10) having: an electronic component (2); a metal plate (4) having two flat sides (4a, 4b) and a surrounding edge (4c); the electronic component (2) is attached to the metal plate (4), the plastic component (6) is attached to at least one of the flat sides (4a, 4b) of the metal plate (4) and to the surrounding edge (4c), and the plastic component (6) is shaped in such a way that the plastic component has cooling ribs (8).

Description

Technical Field

[0001] The invention relates to an electronic device, a switching apparatus and a method. Background Art

[0002] The heat loss of electronic components must be dissipated to avoid overheating and thus damage to the electronic components. In particular, in the case of narrow installation space for electronic components and increased currents, such as the starting current of a motor, the problem of sufficient heat dissipation of electronic components is crucial. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to provide an electronic device in which it is ensured that the lost heat of the electronic components can be discharged to a sufficient extent.

[0004] According to the invention, this object is achieved by an electronic device having the features of the invention, a switching device having the features of the invention and a method having the features of the invention.

[0005] The electronic device according to the present invention has at least one electronic component. The electronic component has one or more electronic assemblies. Components in electrical engineering and electronics (abbreviated as: electronic components) should be understood as the smallest unit in a circuit that cannot be further decomposed (DIN 40150: 1979-10 Classification of functional and structural units), such as resistors. Electronic components can be passive electronic components, such as resistors, coils or capacitors. Electronic components can also be active electronic components, such as transistors (IGBT, FET, MOSFET, etc.), diodes, rectifiers, processors / IC (Intergrated Circuit, integrated circuit), LEDs. Electronic components can also be components of power electronics. Electronic components can be, for example, DIAC (bidirectional trigger diode), TRIAC (three-terminal bidirectional thyristor), transistors, MOSFET, IGBT, thyristor, diode, capacitor, etc. in power electronics, or components in control electronics, such as controllers, voltage regulators, resistors, coils, etc. The electronic components can especially be power semiconductors or power semiconductor modules.

[0006] The electronic device according to the invention has at least one metal plate, preferably made of a metal that conducts heat well, is easy to process and is nevertheless reasonably priced. Due to its shape, the metal plate (also called a "metal inlay") has two preferably parallel flat sides and a surrounding edge, wherein the edge connects the two flat sides to one another. The metal plate can have any contour, for example square, rectangular, circular, oval or any other suitable shape. The position and size of the metal inlay are variable; depending on the type of use of the electronic device 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 in order to disperse the waste heat in a targeted manner, or the metal plate can be arranged across the entire electronic component, in which case the costs and benefits must be weighed.

[0007] The electronic device according to the invention has at least one plastic component made of a thermally conductive plastic. The term "thermally conductive plastic" here includes plastics with a thermal conductivity of more than 0.4 W / (mK). According to the definition given here, conventional plastics (such as polycarbonate) are considered to be "thermally non-conductive" plastics; they are characterized by good thermal insulation, wherein the thermal conductivity is generally in the range of 0.1 to 0.4 W / mK. Conversely, the thermal conductivity of a "thermally conductive" plastic is higher than the thermal conductivity of conventional, non-thermally conductive plastics. Preferably, the thermal conductivity of the thermally conductive plastic is greater than 1 W / (mK), preferably greater than 5 W / (mK), more preferably greater than 8 W / (mK).

[0008] The electronic device according to the invention is characterized in that the electronic component is in contact with the metal plate. Insulating intermediate layers, such as air layers, are avoided in order to ensure the best possible heat transfer from the heat-generating electronic component to the metal plate. In this case, the thermally conductive paste can be arranged between the surfaces of the electronic component and the metal plate that are in contact with each other. It is also possible to press the electronic component and the metal plate against each other by means of a mechanical connecting element, such as a screw connection.

[0009] The electronic device according to the present invention is also characterized in that the plastic component is in contact with at least one of the flat sides of the metal plate and the surrounding edge. Insulating intermediate layers, such as air layers, are avoided in order to ensure the best possible heat transfer from the heat-generating electronic component to the metal plate. According to the present invention, a close contact that is conducive to heat transfer is achieved between the plastic component and the metal plate by casting or injecting a liquid heat-conducting plastic on at least one of the flat sides of the metal plate and the surrounding edge.

[0010] The electronic device according to the present invention is also characterized in that the plastic component is shaped so that it has cooling ribs. According to the present invention, the plastic component with cooling ribs is shaped in such a way that the liquid heat-conducting plastic is shaped before it solidifies, for example by casting, so that the liquid heat-conducting plastic forms at least one cooling rib, and when the liquid heat-conducting plastic solidifies, the cooling rib is formed integrally with the plastic component.

[0011] According to the invention, this object is also achieved by a switching device having an electronic device according to the invention. The term "switching device" here includes switching devices, such as relays, and protective devices, such as circuit breakers.

[0012] According to the invention, the technical problem is also solved by a method for producing an electronic device according to the invention, wherein the electronic component is placed against a metal plate, and the plastic component is shaped by casting or injecting a liquid heat-conducting plastic on at least one flat side and a surrounding edge of the metal plate, and the liquid heat-conducting plastic is shaped so that the liquid heat-conducting plastic forms cooling ribs on the plastic component after solidification.

[0013] The invention is based on the idea that the encapsulation of the electronic components with a heat-conducting plastic and a metal plate for dissipating the heat by the plastic encapsulation significantly improves the heat dissipation from the electronic components. In order to better distribute the waste heat of the electronic components, metal plates are stamped into the plastic at the main heat sources of the electronic components (metal inlay), since metal has very good heat dissipation properties, and the waste heat is distributed to the plastic cooling body. The cast-in metal plate achieves an optimal heat transfer (without air insulation).

[0014] Advantageous embodiments and developments of the invention are described in the present invention.

[0015] According to a preferred design of the present invention, the electronic component is designed as a circuit board equipped with heat-generating electronic components, and the electronic components are embedded in the plastic component. Electrical insulation and heat dissipation are achieved by coating or embedding the electronic components in the heat-conducting plastic. By embedding the electronic components in the plastic component made of the heat-conducting plastic, the heat dissipation of the electronic components is significantly improved.

[0016] According to a preferred design of the present invention, the electronic device is enclosed by a separate housing. This may be a housing made of any material (usually plastic), heat-conducting or heat-non-conducting.

[0017] According to a preferred design of the present invention, the cooling ribs are shaped so that the airflow generated by the ventilation device flows along the cooling ribs. The forced convection significantly improves the heat dissipation of the electronic components.

[0018] According to a preferred design of the present invention, the cooling ribs are shaped so that the airflow generated by the ventilation device flows along the cooling ribs and is deflected at the ends of the cooling ribs. The heat dissipation of the electronic components is significantly improved by forced convection. Therefore, the airflow can be changed by means of the cooling ribs. By deflecting the airflow, the heated airflow can be effectively guided out of the housing, thereby significantly improving the heat dissipation of the electronic components.

[0019] According to a preferred design of the present invention, the plastic component is shaped so that the plastic component forms a housing enclosing the electronic component and the metal plate. Advantageously, both the cooling ribs and the housing are made of heat-conducting plastic: the one-piece plastic component having cooling ribs and forming the housing enables significantly improved heat dissipation of the electronic component.

[0020] By heat-conducting plastic and direct casting, the entire housing acts as a cooling element. By better heat dissipation of the new housing material (ie heat-conducting plastic), a housing with significantly smaller installation space is possible compared to a housing with conventional materials (non-heat-conducting plastic).

[0021] According to a preferred design of the present invention, the electronic component is connected to the metal plate by means of a screw connection. Advantageously, a close contact between the electronic component and the metal plate is achieved, so that the heat dissipation of the electronic assembly can be significantly improved. By means of the screw connection, the insulating air layer between the electronic component and the metal plate is largely avoided or minimized.

[0022] According to a preferred design of the present invention, the metal plate is made of aluminum or copper, both of which are metals with good thermal conductivity, easy processing and reasonable price.

[0023] According to a preferred embodiment of the method, the metal plate is first fed as an insert into an injection molding tool and is sheathed with a heat-conducting plastic by the injection molding process, so that a plastic-metal hybrid is produced. The electronic components are then fixed to the flat side of the metal plate.

[0024] According to a preferred embodiment of the method, the electronic component is fastened to the flat side of the metal plate by means of a screw connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be described below according to a number of embodiments with reference to the accompanying drawings. The accompanying drawings are shown schematically and not to scale. In the accompanying drawings:

[0026] Figure 1 A first embodiment of an electronic device according to the present invention is shown;

[0027] Figure 2 A second embodiment of the electronic device according to the present invention is shown;

[0028] Figure 3 A known electronic device is shown;

[0029] Figure 4 A third embodiment of the electronic device according to the present invention is shown;

[0030] Figure 5 Shows Figure 4 An oblique view of an electronic device;

[0031] Figure 6 A fourth embodiment of an electronic device according to the present invention is shown;

[0032] Figure 7 Shows Figure 6 An oblique view of an electronic device;

[0033] Figure 8 A fifth embodiment of an electronic device according to the present invention is shown;

[0034] Fig. 9 Shows Figure 8 An oblique view of the electronic device; and

[0035] Fig.10 A switchgear is shown. DETAILED DESCRIPTION

[0036] Figure 1 A first embodiment of an electronic device 10 according to the invention is shown in cross section. The electronic device 10 has an electronic component 2, a metal plate 4 and a plastic component 6 made of heat-conducting plastic. The square metal plate 4 has two flat sides (i.e., an upper flat side 4a and a lower flat side 4b) and a surrounding edge 4c that connects the two flat sides 4a, 4b to each other. Here, the electronic component 2 is abutted against the upper flat side 4a of the metal plate 4 and is held there by a screw connection 16, which presses the electronic component 2 to the upper flat side 4a of the metal plate 4. Here, the pressing is carried out in such a way that an insulating air layer cannot be formed between the electronic component 2 and the metal plate 4.

[0037] The plastic component 6 is in contact with the entire surface of the lower flat side 4b of the metal plate 4, the entire surface of the surrounding edge 4c of the metal plate 4, and a portion of the surface of the upper flat side 4a of the metal plate 4. In addition, the plastic component 6 is in contact with a portion of the electronic component 2. The plastic component 6 is shaped so that the plastic component forms a housing 12 that encloses the electronic component 2 and the metal plate 4 and surrounds an air space 14 above the electronic component 2 and the metal plate 4. Here, the plastic component 6 also has cooling ribs 8 protruding downward from the lower side 18 of the housing 12, which covers the lower flat side 4b of the metal plate 4.

[0038] The electronic device 10 is manufactured by placing the electronic component 2 on the upper flat side 4a of the metal plate 4 and fixing it to the metal plate 4 by means of a screw connection 16. Then, the plastic component 6 is shaped by casting or injecting a liquid heat-conducting plastic onto the lower flat side 4b, the edge 4c and a part of the upper flat side 4a of the metal plate and a part of the electronic component 2. Here, the liquid heat-conducting plastic is shaped so that it forms cooling ribs on the plastic component 6 after solidification and forms a housing 12 that encloses the electronic component 2 and the metal plate 4.

[0039] The metal plate can first be fed as an insert into an injection molding tool and encapsulated with a heat-conducting plastic by the injection molding process, thereby producing a plastic-metal hybrid. The electronic component is then preferably fixed to the flat side of the metal plate by means of a screw connection.

[0040] Figure 2 A second embodiment of an electronic device 10 according to the invention is shown in cross section. Figure 1 The embodiment shown is almost identical, except that the plastic component 6 made of heat-conducting plastic only bears against the entire surface of the lower flat side 4b of the metal plate 4 and the entire surface of the surrounding 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.

[0041] A person skilled in the art can realize any number of other embodiments 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 plastic component 6 at different coverage levels. By selecting the coverage level, a person skilled in the art can control the heat dissipation of the electronic component 2.

[0042] exist Figure 1 and Figure 2 In the embodiments shown, the housing 12 has no ventilation openings. These embodiments are therefore suitable for protection class IP65. Products with protection class IP65 have comprehensive contact protection: dust cannot penetrate and water jets from any direction are protected. In the case of protection class IP65, ventilation openings are not permitted and accordingly ventilation devices cannot be used. Therefore, heat cannot be discharged by natural or forced convection.

[0043] Figure 3 The known electronic device is shown in cross section. The electronic component 2 is designed as a printed circuit board 22 (PCB) equipped with heat-generating electronic components 28 ; the electronic components 28 are arranged on two flat sides of the circuit board 22 extending in the xz plane.

[0044] The electronic components 28 are passive and active electronic components, including power semiconductors or power semiconductor modules 29. A metal cooling body 20 made of an extruded aluminum profile is arranged on the flat side of the power semiconductor module 29 facing away from the circuit board 22, which has the largest extension in the y direction, i.e. protrudes the farthest vertically from the circuit board. The cooling body 20 is designed as a metal plate 4, which carries cooling ribs 8 on the flat side facing away from the power semiconductor module 29.

[0045] The electronic device further comprises a housing 12, which encloses the electronic component 2 and the cooling body 20, and surrounds two air spaces 14 on both sides of the circuit board 22, above and below the electronic component 2 and the metal plate 4. Here, the housing has ventilation slots 26 on the housing wall pointing in the positive y direction, and the ventilation slots are used for convection heat dissipation of the electronic component 2.

[0046] In view of the fact that the metal cooling body 20 is electrically conductive, a safety distance 24 must be maintained between the cooling body 20 and the ventilation gap 26 due to the air and creepage distances predetermined by the regulations; in this way, it should be ensured that persons remaining in the area of ​​the device opening formed by the ventilation gap 26 (for example persons touching the ventilation gap 26 with their hands) are not in danger of electric shock.

[0047] Figure 4 A third embodiment of an electronic device according to the present invention is shown in cross section. Figure 3 The known electronic device shown is different in that the electronic components of the electronic component 2 arranged on the circuit board 22 are covered by a plastic component 6 formed of a thermally conductive plastic. A metal plate 4 made of copper is arranged on the flat side of the power semiconductor module 29 facing away from the circuit board 22. The metal plate 4 is also covered by the plastic component 6. The plastic component 6 also forms cooling ribs 8, which protrude along the y-axis in the direction away from the circuit board 22.

[0048] Due to the fact that the cooling ribs 8 formed from heat-conducting plastic are not electrically conductive, it is not necessary to maintain a safety distance 24 between the cooling ribs 8 and the ventilation slots 26. As a result, the housing can be designed to be smaller and the air space 14 can be better utilized.

[0049] Figure 5 Shows Figure 4 1. An oblique view of an electronic device. It can be seen that the metal plate 4 arranged in the xz plane for dispersing heat is square. The cooling ribs 8 extend in the z direction.

[0050] Figure 6 and Figure 7 A fourth embodiment of the electronic device according to the present invention is shown, wherein: Figure 6 is the cross section of the electronic device, Figure 7is an oblique view of an electronic device. In this embodiment, the cooling ribs form a grid of individual cooling "towers". This increases the area of ​​the cooling ribs for dissipating heat and improves convection. The design of the cooling ribs 8 made of plastic makes manufacturing much easier than using metal; therefore, a variety of rib shapes can be realized simply and cost-effectively, for example by means of casting or injection molding. Therefore, the shapes of the possible cooling ribs in the electronic device according to the invention are not as strictly limited as in conventional extruded cooling bodies.

[0051] Figure 8 and Fig. 9 A fifth embodiment of the electronic device according to the present invention is shown, wherein: Figure 8 is the cross section of the electronic device, Fig. 9 2 is an oblique view of the electronic device. In this embodiment, the cooling ribs 8 extend along the longitudinal axis of the circuit board 22 in the x direction, which is different from the Figure 4 and Figure 5 In contrast to the third embodiment shown in FIG. 1 , the cooling ribs 8 extend in the z direction. The forced air flow 30 originating from the ventilator 36 flows along the cooling ribs (ventilator direction) and is deflected outwards by 90 degrees (blowing direction) at the ends of the cooling ribs 8 facing away from the ventilator 36 by the bending of the cooling ribs 8.

[0052] Fig.10 The switchgear 100 is shown. The switchgear 100 has a housing 20 with load current connections 40, 40', which are subdivided into an input terminal 40 and an output terminal 40'. The load current line 42 is electrically connected to the load current connection 40, 40' so that the switchgear 100 is connected between the two ends of the load current line 42. Inside the housing 20, the load current connection 15 is electrically connected to the electronic device 10 by means of a current path 44.

[0053] Reference numerals list

[0054] 2 Electronic components

[0055] 4 Metal Plate

[0056] 4a Flat side

[0057] 4b Flat side

[0058] 4c Wrap around edge

[0059] 6Plastic components

[0060] 8 cooling ribs

[0061] 10 Electronic devices

[0062] 12 Housing

[0063] 14 Air Space

[0064] 16 Threaded connection

[0065] 18 The lower side of the housing 12

[0066] 20 cooling bodies

[0067] 22 Circuit board, PCB

[0068] 24 Safe Distance

[0069] 26 Ventilation Slits

[0070] 28 Electronic components

[0071] 29 Power semiconductor or power semiconductor module

[0072] 30 Airflow

[0073] 32 Ventilation direction

[0074] 34 Blowing direction

[0075] 36 Ventilation

[0076] 40 Load current connector

[0077] 40′ load current connector

[0078] 42 Load current circuit

[0079] 44 Current Path

[0080] 100 Switchgear and / or Protection Equipment

Claims

1. An electronic device (10), comprising: - electronic components (2), - a metal plate (4) having two flat sides (4a, 4b) and a surrounding edge (4c), and - a plastic component (6) made of a heat-conducting plastic, in, - the electronic component (2) is in contact with the metal plate (4), The plastic component (6) bears against at least one of the flat sides (4a, 4b) of the metal plate (4) and against the surrounding edge (4c), and The plastic component (6) is shaped in such a way that it has cooling ribs (8).

2. The electronic device (10) according to claim 1, in, The electronic component (2) is designed as a circuit board (22) equipped with heat-generating electronic components (28), and The electronic component (28) is embedded in the plastic component (6).

3. The electronic device (100) according to any one of the preceding claims, The electronic device is enclosed by a separate housing (12).

4. The electronic device (100) according to any one of the preceding claims, in, The cooling ribs (8) are shaped in such a way that an air flow (30) generated by a ventilation device (36) flows along the cooling ribs (8).

5. The electronic device (100) according to any one of the preceding claims, in, The cooling ribs (8) are shaped in such a way that an air flow (30) generated by a ventilation device (36) flows along the cooling ribs (8) and is deflected at the ends of the cooling ribs (8).

6. The electronic device (100) according to claim 1, in, The plastic component (6) is shaped such that it forms a housing (12) which encloses the electronic component (2) and the metal plate (4).

7. The electronic device (100) according to any one of the preceding claims, in, The electronic component (2) is connected to the metal plate (4) by means of a screw connection (16).

8. The electronic device (100) according to any one of the preceding claims, in, The metal plate (4) is made of aluminum or copper.

9. A switchgear (100) having an electronic device (10) according to any one of the preceding claims.

10. A method for manufacturing an electronic device (100) according to any one of the preceding claims, wherein: The electronic component (2) and the metal plate (4) are placed against each other, and The plastic component (6) is formed by casting or injecting liquid heat-conducting plastic on at least one flat side (4a, 4b) and the surrounding edge (4c) of the metal plate (4), and the liquid heat-conducting plastic is formed so that the liquid heat-conducting plastic forms cooling ribs (8) on the plastic component (6) after solidification.

11. The method according to claim 10, wherein: The metal plate (4) is first introduced as an insert into an injection molding tool and sheathed with a heat-conducting plastic by an injection molding process, thereby producing a plastic-metal hybrid part, after which the electronic component (2) is fixed to the flat side (4a) of the metal plate (4).

12. The 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.

Images