SEMICONDUCTOR DEVICE-METAL OXIDE VARISTOR-HEAT SINK ASSEMBLY

• US 3,745,505 A
• Filed: 10/21/1971
• Issued: 07/10/1973
• Est. Priority Date: 10/21/1971
• Status: Expired due to Term

• Current Assignee: Fred C. Turnbull, John D. Harnden Jr
• Original Assignee: Fred C. Turnbull, John D. Harnden Jr
• Inventors: Harnden, John D. Jr., Turnbull, Fred C.
• Primary Examiner(s): Albritton, C. L.
• Application Number:
  US05/191,168
• Time in Patent Office: 628 Days
• Field of Search: 378/13,20,21 317/234A 165/80
• US Class Current: 338/20
• CPC Class Codes: H01L 25/03 all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

A single or plurality of metallic plates arranged in parallel relationship along the length of a body of metal oxide material in contact therewith provide a means for removal of heat developed in the bulk of the metal oxide material. The metal oxide material exhibits highly nonlinear resistance characteristics to provide transient voltage protection for semiconductor devices connected on or between the metallic plates or between the metallic plates and terminals mounted along the body of metal oxide material at selected voltage points.

Claims

2. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein said metallic plates are oriented perpendicular to the longitudinal axis of the body of metal oxide material.

3. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein the second electrode of said semiconductor device is connected to a terminal lug in contact with the body of metal oxide material at the selected voltage point.

4. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein the second electrode of said semiconductor device is connected to a second of said metallic plates in contact with the body of metal oxide material at the selected voltage point.

5. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein a plurality of said semiconductor devices are interconnected in the assembly and at least the first electrodes of each of said semiconductor devices are directly connected to the metallic plates.

6. The semiconductor device-varistor-heat sink assembly set forth in claim 5 wherein said plurality of semiconductor devices are connected in series circuit relationship.

7. The semiconductor device-varistor-heat sink assembly set forth in claim 5 wherein said plurality of semiconductor devices are connected in bridge circuit relationship.

8. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein said body of metal oxide material is a single right circular cylindrical body, said metallic plates provided with aligned holes for passage of said body of metal oxide material therethrough and having the sides of the holes in contact with the side of said body of said metal oxide material at the selected voltage points.

9. The semiconductor device-varistor-heat sink assembly set forth in claim 8 wherein said plates are equally spaced along said body of metal oxide material.

10. The semiconductor device-varistor-heat sink assembly set forth in claim 8 wherein at least one of said plates is unequally spaced from the other plates along said body of metal oxide material.

11. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein said body of metal oxide material is a plurality of right circular cylindrical bodies.

12. The semicoNductor device-varistor-heat sink assembly set forth in claim 11 wherein said plurality of cylindrical bodies of metal oxide material are each of equal thickness whereby each body provides the same level of voltage suppression.

13. The semiconductor device-varistor-heat sink assembly set forth in claim 11 wherein at least one of said cylindrical bodies of metal oxide material is of thickness unequal to the thickness of the other bodies to provide a different level of voltage suppression, said bodies of metal oxide material being separated from each other by the metallic plates passing therebetween.

14. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein said metallic plates are each of equal dimension.

15. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein at least one of said plates is of unequal dimension compared to the other plates.

16. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein selected of said metallic plates are provided with holes for accommodating a semiconductor device having its first electrode connected directly to another of said metallic plates.

17. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein selected of said metallic plates are provided with holes for passage of electrical conductors from the second electrode of the semiconductor device for interconnection to the predetermined point along said body of said metal oxide material, the interconnecting conductors being of short length due to the compactness of the assembly whereby unwanted inductance introduced by the interconnecting conductors is minimized.

18. The semiconductor device-varistor-heat sink assembly set forth in claim 11 wherein said bodies of metal oxide material are in alignment and retained in rigid contact with said plates.

19. The semiconductor device-varistor-heat sink assembly set forth in claim 11 wherein said bodies of metal oxide material are in alignment and at least one end surface of each body of metal oxide material is in rigid contact with a corresponding one of said plates.

20. The semiconductor device-varistor-heat sink assembly set forth in claim 11 wherein said bodies of said metal oxide material are in alignment and the intermediate bodies have both end surfaces thereof in rigid contact with said plates.

21. The semiconductor device-varistor-heat sink assembly set forth in claim 11 and further comprising means for retaining said bodies of metal oxide material and said plates in a single rigid assembly.

22. The semiconductor device-varistor-heat sink assembly set forth in claim 11 wherein said bodies of metal oxide material are positioned in a staggered relationship between the metallic plates to form a pattern wherein alternate bodies are in alignment to provide a structurally rigid assembly.

23. The semiconductor device-varistor-heat sink assembly set forth in claim 11 wherein said plates are staggered in a circular staircase pattern whereby said assembly is especially adapted for high voltage applications.

24. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein said body of metal oxide material comprises at least one body for each phase of a polyphase semiconductor circuit, the bodies in each phase being arranged in spaced apart parallel relationship to the bodies in the other phases, a first and second of said plurality of metallic plates being of greater length dimension and forming the outermost plates of the assembly and retaining end portions of said bodies of metal oxide material, the remainder of said plurality of metallic plates connected along the lengths of said bodies of metal oxide material intermediate said outermost plates, said intermediate plates being of smaller length than said outermost plates and arranged in a plurality of separate stacks equal to the number of phases in the semiconducTor circuit.

25. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein the second electrode of said semiconductor device is connected to a second of said plates positioned along said body of metal oxide material at the selected voltage point.

26. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein the second electrode of said semiconductor device is connected to a terminal lug positioned along said body of metal oxide material at the selected voltage point.

27. The semiconductor device-varistor-heat sink assembly set forth in claim 11 wherein said bodies of metal oxide material are hollow.

28. The semiconductor device-varistor-heat sink assembly set forth in claim 11 wherein said bodies of metal oxide material are solid.

29. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein said body of metal oxide material has an alpha exponent in excess of 10.

30. The semiconductor device-varistor-heat sink assembly set forth in claim 1 wherein said body of metal oxide material is composed primarily of zinc oxide.

31. A metal oxide varistor-heat sink assembly comprising a plurality of bodies of sintered metal oxide material exhibiting highly nonlinear resistance characteristics, first and second metallic plates disposed in parallel relationship to each other and in contact with the outermost end portions of said bodies of metal oxide material, said bodies comprising at least one body for each phase of a polyphase circuit to be protected against transient voltages, the bodies in each phase being arranged in spaced apart parallel relationship to the bodies in the other phases, a plurality of metallic plates of smaller size than said first and second plates, said plurality of plates disposed along the lengths of said bodies of metal oxide material at predetermined points thereof and in contact therewith intermediate said first and second plates and parallel therewith, said first, second and plurality of plates oriented perpendicular to the longitudinal axes of said bodies of metal oxide material, said intermediate plates arranged in a plurality of separate stacks equal to the number of the phases to be protected, said plates providing a means for removal of heat developed in the bulk of the bodies of metal oxide material, and electrical conductor means connected to selected of said metallic plates for connecting said selected plates to a source of voltage which may be subjected to transient voltages, the highly nonlinear resistance characteristics of the metal oxide material limiting the voltage appearing between the metallic plates in accordance with the thickness dimensions of the metal oxide material therebetween.

32. The metal oxide varistor-heat sink assembly set forth in claim 31 wherein said electrical conductor means are connected to said first and second metallic plates.

33. The metal oxide varistor-heat sink assembly set forth in claim 31 wherein said electrical conductor means are connected to centermost plates in each stack of plates.

34. The metal oxide varistor-heat sink assembly set forth in claim 33 and further comprising a variable resistor connected across said first and second metallic plates whereby said assembly forms an alternating current dynamic braking network with means for varying the LR time constant of the dynamic braking circuit.

35. The metal oxide varistor-heat sink assembly set forth in claim 34 wherein said variable resistor is an active semiconductor circuit means for providing variable impedance.

36. The metal oxide varistor-heat sink assembly set forth in claim 31 and further comprising a plurality of semiconductor devices each provided with at least two electrodes, said semiconductor devices connected in a desired circuit relationship and each device having at least a first of its electrodes connected directly to a corresponding one of said metallic plaTes whereby said plates also provide a means for removal of heat developed in the semiconductor devices and mechanical support therefor, the second electrodes of said semi-conductor devices connected to predetermined points along said bodies of metal oxide material corresponding to selected voltages, the nonlinear resistance characteristics of the metal oxide material limiting the voltages appearing between the metallic plates and selected voltage points in accordance with the thickness dimensions of the metal oxide material therebetween to thereby provide transient voltage suppression protection for the semi-conductor devices.

37. A metal oxide varistor-heat sink assembly comprising a body of sintered metal oxide material exhibiting highly nonlinear resistance characteristics, at least one metallic plate disposed along the length of said body of metal oxide material and normal to the longitudinal axis of said body, means for supporting said body of metal oxide material on said plate whereby said plate provides a heat-sink for the body of metal oxide material, and means for supporting the metal oxide body-metallic plate assembly on a second assembly associated therewith.

38. The metal oxide varistor-heat sink assembly set forth in claim 37 and further comprising at least one semiconductor device mounted on said metallic plate whereby said plate also provides a heat-sink for said semiconductor device, a second electrode of said semiconductor device connected to a point on said body of metal oxide material longitudinally displaced from the point of connection of said plate whereby the highly nonlinear resistance characteristics of the metal oxide material limit the voltage appearing across said semiconductor device to provide transient voltage protection therefor, the interconnection of the second electrode to the body of metal oxide material being of short length to minimize the unwanted inductance introduced thereby.