Electric device

Abstract

An electric device having a printed circuit board fitted with components, and at least one foam component, the foam component surrounding the circuit board at least partially so as to form a housing.

Claims

1. An electric device, comprising: a printed circuit board fitted with components including at least one foam component, wherein the at least one foam component surrounds the circuit board at least partially so as to form a housing; and wherein a metallic part is disposed in the foam component and projects from the foam component into the environment and is set apart from the circuit board and the components assembled thereon.

2. The electric device as recited in claim 1, wherein the at least one foam component includes an expanded base material that includes polypropylene and a nonoxide ceramic material, the nonoxide ceramic material including at least one of silicon carbide, boron nitride, and boron carbide.

3. The electric device as recited in claim 2, wherein the nonoxide ceramic material is present at a volumetric component of between 3% and 30%.

4. The electric device as recited in claim 1, wherein the circuit board is fitted with at least one heat-generating component.

5. The electric device as recited in claim 1, wherein the at least one foam component includes a plurality of foam components interconnected in form-locking manner.

6. The electric device as recited in claim 5, wherein the foam components are interconnected by one of a screwed connection and a clip-in connection.

7. The electric device as recited in claim 1, wherein the electric device is able to be screwed to an assembly part by screws that introduce a clamping force into the foam component.

8. The electric device as recited in claim 7, wherein the assembly part is metallic.

9. The electric device as recited in claim 7, further comprising: a heat-generating power module linked to the circuit board and, on a side facing away from the circuit board, connected to a heat sink which penetrates the foam component and which discharges into an environment.

10. The electric device as recited in claim 9, wherein the heat sink is an aluminum heat sink.

11. The electric device as recited in claim 9, wherein the heat sink discharges into the assembly part, on a side of the assembly part facing away from the power module.

12. The electric device as recited in claim 1, wherein the circuit board includes at least one plug connector that projects from the foam component.

13. The electric device as recited in claim 12, wherein the plug connector is for a connection with a mating connector part.

14. The electric device as recited in claim 1, wherein the metallic part is one of aluminum and copper.

15. The electric device as recited in claim 9, wherein the power module is connected to the circuit board by screws, wherein a pressure plate is pressed against the circuit board by a screw connection on a side facing away from the power module, and wherein the power module is pressed against the circuit board by the screw connection.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a cross-section through the schematic structure of an exemplary embodiment of the present invention.

(2) FIG. 2 shows a cross-section through the schematic structure of a second exemplary embodiment of the present invention.

(3) FIG. 3 shows an oblique view of the first or second exemplary embodiment.

DETAILED DESCRIPTION

(4) As illustrated in FIG. 1, a circuit board 5, on which a heat-generating component 6 is mounted, is surrounded by foam components (1, 2) on both sides.

(5) For this purpose a first foam component 1 is placed against the first side of circuit board 5, on which component 6 is situated as well.

(6) A power module 9, which is provided with power semiconductors and consequently generates a high heat output, is mounted on the other side of circuit board 5. Circuit board 5 together with power module 9 is surrounded by second foam component 2.

(7) Both foam components (1, 2) simultaneously constitute the housing. That is to say, they surround the circuit board assembly in the form of a housing.

(8) In addition, at least one, or both, foam component(s) (1, 2) is/are made from a heat-conductive base material.

(9) The base material consists of polypropylene, a nonoxide ceramic material, such as silicon carbide, boron nitride and/or boron carbide, and additional additives for enhancing the flameproofing and reducing creeping currents, i.e., for improving the electrical insulating capability. The volumetric component of the ceramic material, which is added as a fine powder during the production, amounts to between 3% and 30%. Excellent thermal conductivity is therefore achievable, although the base material is expanded and thus is produced as a foam component having a high percentage of gas inclusions. Although the gas inclusions are poor heat conductors, the chains formed by the ceramic material particles are disposed as partially interrupted chains in the cell walls formed by the base material, from the heat source to the heat sink, in such a way that very low thermal resistivity is realizable by the foam component(s).

(10) The foam components (1, 2) hold the circuit board assembly mechanically as well and are pressed against an assembly part 12, especially a table or wall, by screws 3, which preferably have a broadened screw head and/or under whose screw head a washer is disposed, in that screws 3 are at least partially screwed in there.

(11) On the same side of circuit board 5 on which power module 9 is situated as well, a capacitor 4 is provided, which acts as intermediate circuit capacitor of the rectifier realized by the circuit board assembly.

(12) Heat-generating component 6 is connected by soldering to circuit tracks of the circuit board via its connection elements.

(13) In contrast, a screw 7 is provided to connect power module 9 to circuit board 5, the screw head pressing against a pressure plate 8, which, like the screw head, is situated on the side of the circuit board facing away from the power module.

(14) To generate this clamping force, screw 7 is connected to a nut 10, which in turn presses on the power module via a pressure plate, nut 10 and pressure plate 11 being situated on the side of the power module that faces away from the circuit board.

(15) Via a solder joint, a plug connector part is additionally connected to circuit board 5, whose contacts project from foam component 2, so that a mating plug part is able to be connected from the outside. In this way the circuit board can be connected to a data bus or to some other device by means of another data interface.

(16) As shown in FIG. 3, a further plug connector part 30 is additionally able to be soldered to circuit board 5, so that supply lines are connectible via a mating plug connector part which is likewise able to be connected to the contacts of the plug connector part 30 projecting from foam component 2.

(17) In this manner, a circuit board is therefore able to be fitted with components, a module and plug connector parts, whereupon the circuit board assembly is enclosed by foam components, especially by correspondingly hot-stamped foam components.

(18) The electric device created in this manner is able to be transported and fastened to an assembly part 12.

(19) Instead of the foam components, an envelopment by foam in a tool is another option. For this purpose, for example, the circuit board is placed in the tool, surrounded by spherical base material particles, then exposed to the action of hot water vapor, chemically foamed up and/or foamed up using a multicomponent mixture.

(20) This makes it possible to dispense with the production of individual foam material parts, and the housing can be produced in a single step.

(21) As shown in FIG. 2, it is also possible to connect a heat sink 20 to power module 9, so that the heat of the power module is able to be routed out of the housing, formed by foam components (1, 2), into the environment, especially assembly part 12, by the direct contact of power module 5 with heat sink 20. The heat that is generated by component 6 and/or capacitor 4 is furthermore dissipated to the environment via heat-conducting foam components 1 or 2.

(22) In one further exemplary embodiment according to the present invention, instead of the two foam components (1, 2), more or fewer foam material components are used to assume the housing function, the heat-conduction function, and the mechanical holding function for the circuit board and the components assembled thereon.

LIST OF REFERENCE NUMERALS

(23) 1 foam component, especially foam plastic component 2 foam component 3 screw, especially one having a broadened screw head and/or a washer 4 capacitor 5 circuit board 6 heat-generating component 7 screw 8 pressure plate 9 power module 10 nut 11 pressure plate 12 assembly part, especially a table or wall 13 plug connector part 20 heat sink 30 plug connector part