electrical appliance

Abstract

electrical appliance, comprising a populated circuit board (5) and at least one foam part (1) wherein the foam part (1) at least partially surrounds the circuit board (5) in a housing-forming manner, characterized by the fact that at least one connector part (13) is mounted on the circuit board (5), which protrudes from one or the foam part (1), in particular for connection with a mating connector part, wherein a heat-generating power module (9), which is connected to the circuit board (5), is connected on a side facing away from the circuit board (5) to a heat sink (20), in particular to an aluminum heat sink, which penetrates a foam part (1), wherein a metallic part, in particular made of aluminium or copper, is arranged in the foam, which protrudes from the foam into the environment and is spaced apart from the circuit board (5) and the components (6) mounted on it.

Description

[0001] The invention relates to an electrical device.

[0002] It's well known that foam can be used as a thermal barrier. Electrical device casings are made of metal or plastic.

[0003] The closest prior art known from WO 99 / 59225 A1 is a foam housing for a printed circuit board.

[0004] DE 42 37 870 A1 discloses a method for producing an electronic control unit for a motor vehicle.

[0005] An electrical device is known from the subsequently published DE 10 2011 010 434 A1.

[0006] An electrical device is known from DE 44 37 664 A1.

[0007] An electrical power distributor is known from DE 10 2008 060 062 A1.

[0008] From CN 2339275 Y a printed circuit board arranged in a ball-shaped plastic housing is known.

[0009] The invention is therefore based on the object of developing an electrical device which should enable the simplest possible manufacture.

[0010] According to the invention, the object is achieved in the electrical device according to the features specified in claim 1.

[0011] Important features of the invention in the electrical device, comprising a populated circuit board and at least one foam part wherein the foam part at least partially surrounds the circuit board to form a housing.

[0012] The advantage here is that the heat is dissipated through the foam. This means that the foam does not function as a thermal barrier, but rather as a heat-dissipating housing element. Despite its low mass, the foam's impact energy absorption capacity is very high. This provides good protection for the circuit board.

[0013] Thus, the foam, which acts as a cooling arrangement for the heat-generating components, also functions as an electrical insulator, contact protection and housing.

[0014] Foam refers to expanded plastics with a volume fraction of gas inclusions or gas bubbles of more than 50%. Foaming involves adding foam additives to a base material, which at least doubles the volume of the material. Preferably, beads of the foamed base material are exposed to hot steam in a mold so that the beads fuse, i.e., are bonded together, and the entire body takes on the shape specified by the mold.

[0015] In an advantageous embodiment, the foam consists of a foamed base material which contains polypropylene and a non-oxidic ceramic material,

[0016] in particular which comprises silicon carbide, boron nitride and / or boron carbide, especially with a volume fraction between 3% and 30%. The advantage here is that foam can be made heat-conductive using simple means.

[0017] In an advantageous embodiment, one or more heat-generating components are mounted on the circuit board. The advantage here is that the heat is dissipated to the environment through the housing, even though the housing is made of foam.

[0018] In an advantageous embodiment, the foam parts are connected to one another in a form-fitting manner, particularly by screwing or clipping. This provides a simple and secure connection.

[0019] According to the invention, the electrical device can be screwed to a mounting part, in particular a metal mounting part, by means of screws, whereby the screws introduce contact pressure into or into the foam part. Advantageously, the heat generated by the electrical device can be transferred from the mounting part.

[0020] According to the invention, a heat-generating power module, which is connected to the circuit board, is connected on a side facing away from the circuit board to a heat sink, in particular an aluminum heat sink, which penetrates a foam part, in particular, and opens into the environment, in particular into the mounting part, on its side facing away from the power module. Advantageously, a large heat flow can be dissipated to the environment via a heat sink. The additional heat flows generated by the electrical device are dissipated via the foam.

[0021] According to the invention, at least one connector part is mounted on the circuit board, which protrudes from one or more of the foam parts, particularly for connection to a mating connector part. This is advantageous because electrical connections protrude from the foam and can thus be contacted. The connector part can be automatically populated during the assembly of the circuit board, making production simple and cost-effective.

[0022] In an advantageous embodiment, a metallic part, particularly made of aluminum or copper, is arranged in the foam. This metallic part protrudes from the foam into the surrounding area and is spaced apart from the circuit board and the components mounted on it. This is advantageous in that improved heat dissipation can be achieved. While the specific thermal conductivity of the foam is better than air, in particular at least ten times better, it is worse than that of copper and also that of aluminum.

[0023] In an advantageous embodiment, the power module is screw-connected to the circuit board,

[0024] In particular, a pressure plate is pressed against the circuit board by a screw connection on the side facing away from the power module, and the power module is pressed against the circuit board by the screw connection. This is advantageous in that a low pressure is generated in the contact area. The pressure plate is made of plastic or is constructed in two pieces, with an electrically insulating plastic part arranged toward the circuit board, which is pressed against the circuit board by a metallic plate.

[0025] Further advantages emerge from the dependent claims. The invention is not limited to the combination of features in the claims. Further possible combinations of claims and / or individual claim features and / or features of the description and / or the figures will become apparent to those skilled in the art, particularly from the problem and / or the problem posed by comparison with the prior art.

[0026] The invention will now be explained in more detail with the aid of illustrations: In the Fig. 1 shows a cross section through the schematic structure of an embodiment according to the invention.

[0027] In the Fig. 2 shows a cross section through the schematic structure of a second embodiment according to the invention.

[0028] In the Fig. 3 shows an oblique view of the first or second embodiment.

[0029] As in Fig. 1, a circuit board 5 equipped with a heat-generating component 6 is surrounded on both sides by foam parts (1, 2).

[0030] For this purpose, a first foam part 1 is attached to the first side of the circuit board 5, on which the component 6 is also arranged.

[0031] On the other side of the circuit board 5, a power module 9 is mounted, which contains power semiconductors and thus also has high thermal performance. The circuit board 5, including the power module 9, is surrounded by the second foam part 2.

[0032] The two foam parts (1, 2) also form the housing. They surround the assembled circuit board, forming the housing.

[0033] In addition, at least one or both foam parts (1, 2) are made of thermally conductive base material.

[0034] The base material consists of polypropylene, a non-oxide ceramic material such as silicon carbide, boron nitride, and / or boron carbide, and other additives to improve flame retardancy and reduce leakage current, thus improving electrical insulation strength. The volume fraction of the ceramic material, which is added as a fine powder during production, is between 3% and 30%. This allows for excellent thermal conductivity, even though the base material is foamed and thus produced as a foam part with a high proportion of gas inclusions. While these gas inclusions conduct heat very poorly, the chains formed by the ceramic material particles in the cell walls formed from the base material are arranged as partially interrupted chains from the heat source to the heat sink, allowing very low thermal resistance to be achieved through the foam part(s).

[0035] The foam parts (1, 2) also hold the populated circuit board mechanically and are pressed against a mounting part 12, in particular a table or wall, by means of screws 3, which preferably have a widened screw head and / or under whose screw head a washer is arranged, in that the screws 3 are at least partially screwed in there.

[0036] On the same side of the circuit board 5 on which the power module 9 is located, a capacitor 4 is also provided, which functions as an intermediate circuit capacitor of the converter realized by the assembled circuit board.

[0037] The heat-generating component 6 is soldered to the conductor tracks of the circuit board with its connecting elements.

[0038] On the other hand, a screw 7 is provided for connecting the power module 9 to the circuit board 5, the screw head of which presses on a pressure plate 8 which - like the screw head - is located on the side of the circuit board facing away from the power module.

[0039] To generate this contact force, the screw 7 is connected to a nut 10, which in turn presses onto the power module via a pressure plate, wherein the nut 10 and the pressure plate 11 are arranged on the side of the power module facing away from the circuit board.

[0040] A connector part is also soldered to the circuit board 5, whose contacts protrude from the foam part 2, allowing a mating connector part to be connected from the outside. In this way, the circuit board can be connected to a data bus or to another device via another data interface.

[0041] As in Fig. 3, a further connector part 30 can also be soldered to the circuit board 5, so that supply lines can be connected via a mating connector part, which can be connected to the contacts of the connector part 30, which also protrude from the foam part 2.

[0042] In this way, a printed circuit board can be equipped with components, a module and connector parts, after which the assembled printed circuit board is surrounded by foam parts, in particular by appropriately hot-embossed foam parts.

[0043] The resulting electrical device is transportable and can be attached to an assembly part 12.

[0044] Instead of foam parts, encapsulation within a mold is also possible. For example, the circuit board is placed in the mold, surrounded by spherical base material particles, and then exposed to hot steam, chemically foamed, and / or foamed with a multi-component mixture.

[0045] In this way, the production of individual foam parts is no longer necessary and the housing can be manufactured in a single step.

[0046] As in Fig.2, a heat sink 20 can also be connected to the power module 5, so that the heat of the power module can be conducted out of the housing formed by the foam parts (1, 2) via the direct contact of the power module 5 with the heat sink 20 to the environment, in particular the mounting part 12. The heat generated by the component 6 and / or by the capacitor 4 is further dissipated to the environment via the heat-conducting foam parts 1 and 2, respectively.

[0047] In a further embodiment according to the invention, more or fewer foam parts are used instead of the two foam parts (1, 2) to form the housing function, the heat dissipation function and the mechanical holding function for the circuit board including the components. List of reference symbols 1 foam part, in particular plastic foam part 2 foam parts 3 Screw, especially with enlarged screw head and / or washer 4 Capacitor 5 circuit board 6 Heat-generating component 7 screw 8 printing plate 9 Power module 10 Mother 11 Printing plate 12 Mounting part, especially table or wall 13 Connector part 20 heat sinks 30 connector part

Claims

[1] Electrical appliance, comprising a populated circuit board (5) and at least one foam part (1) wherein the foam part (1) at least partially surrounds the circuit board (5) to form a housing, characterized by , that at least one connector part (13) is mounted on the circuit board (5), which protrudes from one or the foam part (1), in particular for connection to a mating connector part, wherein a heat-generating power module (9), which is connected to the circuit board (5), is connected on a side facing away from the circuit board (5) to a heat sink (20), in particular to an aluminum heat sink, which penetrates a foam part (1), wherein a metallic part, in particular made of aluminium or copper, is arranged in the foam, which protrudes from the foam into the surroundings and is spaced apart from the circuit board (5) and the components (6) mounted thereon. [2] Electrical appliance according to claim 1, characterized by , that the foam consists of a foamed base material which contains polypropylene and a non-oxidic ceramic material, in particular which comprises silicon carbide, boron nitride and / or boron carbide, especially with a volume share between 3% and 30%. [3] Electrical appliance according to at least one of the preceding claims, characterized by that one or more heat-generating components (6) are mounted on the circuit board (5). [4] Electrical appliance according to at least one of the preceding claims, characterized bythat foam parts (1) are connected to one another in a form-fitting manner, in particular by screwing or by means of a clip connection. [5] Electrical appliance according to at least one of the preceding claims, characterized by that the electrical device can be screwed to a mounting part (12), in particular a metallic mounting part (12), by means of screws (3, 7), wherein the screws introduce contact force flow into or into the foam part (1). [6] Electrical appliance according to at least one of the preceding claims, characterized by that the heat sink (20) opens into the environment on its side facing away from the power module (9), in particular into the mounting part (12). [7] Electrical appliance according to at least one of the preceding claims, characterized by , that the power module (9) is screw-connected to the circuit board (5), in particular wherein a pressure plate (8) on the side facing away from the power module (9) is pressed against the circuit board (5) by a screw connection and the power module (9) is pressed against the circuit board (5) by the screw connection.

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