ELECTRIC FUSE ARRANGEMENT WITH A METAL FOAM AND METHOD FOR INTERRUPTING AN ELECTRIC CURRENT USING THE FUSE ARRANGEMENT

Abstract

An electrical fuse configuration or arrangement includes two contact pieces which are placed on top of each other and between which a metal foam is located. A method for interrupting an electric current by using the electrical fuse configuration includes melting the metal foam at a current value exceeding a predetermined threshold or maximum current value.

Claims

1-11. (canceled)

12. An electrical fuse configuration, comprising: two contact pieces disposed on top of one another; and a metal foam disposed between said contact pieces.

13. The electrical fuse configuration according to claim 12, wherein said metal foam forms a metal foam body being dimensioned to effect electrical isolation between said contact pieces upon melting of said metal foam.

14. The electrical fuse configuration according to claim 13, wherein said metal foam body is a constituent part of one of said contact pieces.

15. The electrical fuse configuration according to claim 13, wherein said metal foam body is configured to melt upon a passage through the fuse configuration of a current exceeding a predefined threshold current value.

16. An electrical device, comprising: an electrical fuse configuration including: two contact pieces disposed on top of one another; at least one semiconductor component disposed between said contact pieces; and at least one metal foam body each being associated with a respective semiconductor component to form an electrical series circuit; said at least one metal foam body being dimensioned to effect electrical isolation between said contact pieces and to open said series circuit upon melting of said metal foam body.

17. The electrical device according to claim 16, which further comprises a housing, said contact pieces each forming a respective part of said housing.

18. The electrical device according to claim 16, wherein: said at least one semiconductor component includes a plurality of semiconductor components disposed in parallel between said contact pieces; said at least one metal foam body includes a plurality of metal foam bodies each forming a series circuit with a respective one of said semiconductor components; and each respective series circuit is opened by the melting of said metal foam body of said series circuit.

19. The electrical device according to claim 18, wherein each respective metal foam body is configured to melt upon a short-circuit in said semiconductor component associated with said respective metal foam body in a respective series circuit.

20. The electrical device according to claim 18, wherein said contact pieces, said metal foam bodies and said semiconductor components are mechanically compressed in a pressure assembly.

21. A method for interrupting an electric current in an electrical fuse configuration, the method comprising the following steps: placing two contact pieces of the electrical fuse configuration on top of one another; placing a metal foam between the contact pieces; and melting the metal foam if a current value in the electrical fuse configuration exceeds a predefined threshold current value.

22. The method according to claim 21, which further comprises melting the metal foam due to a passage of current through the contact pieces.

Description

[0029] The invention is described in greater detail hereinafter, with reference to FIGS. 1-4.

[0030] FIG. 1 shows a schematic representation of an exemplary embodiment of a safety arrangement according to the invention.

[0031] FIG. 2 shows a schematic representation of an exemplary embodiment of a safety arrangement according to the invention in an electrical device.

[0032] FIG. 3 shows a schematic representation of a metal foam body of the safety arrangement from FIG. 2.

[0033] FIG. 4 shows a further schematic representation of the electrical device from FIG. 2.

[0034] Specifically, FIG. 1 shows a sketch of an exemplary form of embodiment of the safety arrangement 100 according to the invention. The safety arrangement 100 comprises a first contact piece 101 and a second contact piece 102, which are arranged one on top of the other. A metal foam 103 is arranged between the contact pieces 101, 102. The safety arrangement is a constituent element of a power circuit indicated by the two conductors 104, 105. The power circuit can be, for example, an electrical component.

[0035] During the normal duty of the safety arrangement 100, current flows via the conductor 104, the first contact piece 101, the metal foam 103, the second contact piece 102 and the conductor 105. In the event of a short-circuit on the safety arrangement 100, the short-circuit current specifically initiates a strong heat-up of the two contact pieces 101, 102 and the metal foam 103. If a specific short-circuit current value is exceeded, and the resistance of the safety arrangement 100 is also such that the corresponding temperature value is achieved, the metal foam 103 will melt, thereby reducing its volume. As a result, an isolating gap is formed between the two contact pieces 101, 102. The series circuit formed by the contact pieces 101, 102 and the metal foam is thus separated.

[0036] The flow of current in the safety arrangement 100 is interrupted.

[0037] According to one variant of the invention, the molten metal foam 103 is evacuated from the space between the contact pieces 101, 102 (or flows independently out of said space), thus forming the aforementioned isolating gap.

[0038] FIG. 2 shows a cross-section of one form of embodiment of an electric safety arrangement 100 according to the invention, in a device 1. In the exemplary embodiment represented in FIG. 2, the electrical device 1 is configured as a semiconductor module. The semiconductor module 1 has a housing 2, wherein an upper conductive plate constitutes a part of the housing 2. A lower conductive plate 4 also constitutes a part of the housing 2, namely, the base panel of the housing 2. The upper conductive plate 3 and the lower conductive plate 4 form the two contact pieces of the safety arrangement 100.

[0039] In the housing 2, the semiconductor components 5, 6 and 7, configured as semiconductor chips, are arranged in parallel adjacently to each other. A metal foam body 8 is arranged between the lower conductive plate 4 or semiconductor chip 5 and the upper conductive plate 3. The upper conductive plate 3, the metal foam body 8, the semiconductor chip 5 and the lower conductive plate 4 form an electrical series circuit. Correspondingly, the further semiconductor chips 6 and 7, with their respective associated metal foam bodies 9 or 10 form two further series circuits. In a normal state of duty, as represented in FIG. 2, current flows through the semiconductor module 1, in which it is divided between three series circuits. In this connection, it should be noted that further semiconductor chips may be provided in the semiconductor module 1, although these are not visible in the cross-sectional representation shown in FIG. 2.

[0040] FIG. 3 shows a schematic representation of the metal foam body 8 in the exemplary embodiment of the device according to the invention shown in FIG. 2. The metal foam bodies 9 and 10 from FIG. 2 are of equivalent design to the metal foam body 8. In the exemplary embodiment represented in FIG. 3, the metal foam body 8 is configured with a quadrilateral design. Depending upon the application or the semiconductor geometry, other shapes for the metal foam body, for example cylindrical, disk or spherical shapes, are also conceivable. The metal foam body is comprised of a metal foam. The metal foam is produced by the foaming of a metal powder, using an appropriate propellant. As a result, the metal foam body 8 specifically incorporates pores 11. The size and number of pores 11 dictate the elastic behavior of the metal foam body. The electrical properties of the metal foam body 8 are also influenced by the number and size of the pores 11, and by the shape of the metal foam body 8.

[0041] FIG. 4 shows the semiconductor module 1 from FIG. 2, in which the metal foam body 10 is in a molten state. Identical and equivalent components in FIGS. 2 to 4 are identified by the same reference numbers. In the exemplary embodiment represented in FIG. 4, a defect in the semiconductor chip 7 is assumed, whereby the fault sequence proceeds correspondingly in the event of defects on the remaining semiconductor chips 8 or 9. In the event of a defect of this type, a short-circuit is formed in the current path through the semiconductor chip 7. The resulting high temperatures result in the melting of the metal foam body 10. The volume of the metal foam body 10 is reduced accordingly. The molten metal of the metal foam body 10 forms a drop-shaped solid, the weight of which causes it to descend by gravity, i.e. in the direction of the semiconductor chip 7. An electrically isolating gap 12 is thus formed between the semiconductor chip 7 and the upper conductive plate 3. The series circuit formed by the upper conductive plate 3, the metal foam body 10, the semiconductor chip 7 and the lower conductive plate 4 is separated accordingly. The current flux in the semiconductor chip 7 is interrupted. In this case, the current flowing in the semiconductor module 1 is divided between the two remaining current paths which, in this case, are provided by the respective series circuits formed with the semiconductor chip 5 and the semiconductor chip 6. The functionality of the entire semiconductor module 1 can thus be maintained, even in the event of a short-circuit on the semiconductor module 1.

LIST OF REFERENCE NUMBERS

[0042] 1 Semiconductor module [0043] 2 Housing [0044] 3 Upper conductive plate [0045] 4 Lower conductive plate [0046] 5, 6, 7 Semiconductor chips [0047] 8, 9, 10 Metal foam bodies [0048] 11 Pores [0049] 12 Gap [0050] 100 Safety arrangement [0051] 101, 102 Contact piece [0052] 103 Metal foam [0053] 104, 105 Conductor