Electrical bus with associated porous metal heat sink and method of manufacturing same

• US 6,678,182 B2
• Filed: 03/04/2003
• Issued: 01/13/2004
• Est. Priority Date: 11/07/2000
• Status: Expired due to Fees

• Current Assignee: United Defense LP (BAE Systems Plc)
• Original Assignee: United Defense LP (BAE Systems Plc)
• Inventors: Joseph, Craig, Arnold, Kelly W., Dorsch, T. James, Evans, Anthony C.
• Primary Examiner(s): Vu, Bao Q.
• Application Number:
  US10/382,271
• Publication Number:
  US 20030179596A1
• Time in Patent Office: 315 Days
• Field of Search: 363/141, 363/145, 363/147, 363/689, 363/69, 363/699, 363/704
• US Class Current: 363/141
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections
• CPC Class Codes: H05K 7/20927 Liquid coolant without phase change

Abstract

A module is formed in which semiconductor components are soldered to an electrically conductive heat sink. The electrically conductive heat sink is formed so that it will serve as an electrical bus in an electronic device. The chips of the semiconductor component are metallurgically bonded to the surface of the heat sink. The heat sink uses a heat transfer fluid that flows through an interior of the heat sink, the interior containing an internal element. In the preferred embodiment, the internal element is a plurality of silver plated copper balls. The copper balls are brazed to each other and to the walls of the heat sinks in an assembly process. The heat sink housing will typically be made from copper, with one surface made from molybdenum so that the expansion and contraction of the heat sink housing molybdenum surface will be similar to that of the silicon substrate of the chips, thereby avoiding the problem of the chip substrate cracking and breaking due to thermal flexing.

Claims

1. A module for an electronic device comprising:

at least one semiconductor component and an electrical bus;

wherein

said semiconductor component is metallurgically attached to said electrical bus,

said electrical bus is an electrically conductive heat sink for said semiconductor component, said heat sink comprising an enclosed housing with at least one throughway therein to allow passage of a heat transfer fluid through said heat sink,

said electrically conductive heat sink that is said electrical bus has at least one surface formed from a material that is electrically and thermally conductive that is the mounting surface for said semiconductor component, said material having a coefficient of thermal expansion approximating that of a substrate of said semiconductor component, and

said semiconductor component is attached directly to said mounting surface of said heat sink that is said electrical bus by a metallic material that melts to flow across and wet said surface of said heat sink and said semiconductor component, thereby bonding said semiconductor component to said heat sink so that said semiconductor component is electrically and thermally coupled to said heat sink.

2. The module of claim 1 wherein:

said metallic material used to attach said semiconductor component to said electrical bus has a volume electrical resistivity less than 50 micro-ohm cm at 23°

C. and a thermal conductivity greater than 10 W/m·

°

K at 23°

C.

3. The module of claim 1 wherein:

said metallic material is a solder.

4. The module of claim 3 wherein:

said solder comprises at least one metal of the class of tin, lead, antimony, indium, and silver.

5. The module of claim 1 wherein:

said semiconductor component is a power semiconductor.

6. The module of claim 5 wherein:

said power semiconductor is one of the class of semiconductors commonly known as diodes, thyristors, triacs, gate turn-off thyristors, metal oxide semiconductor controlled thyristors, transistors, bipolar junction transistors, metal oxide semiconductor controlled field effect transistors, and insulated gate bipolar transistors.

7. The module of claim 5 wherein:

said bus carries currents exceeding 100 Amps.

8. The module of claim 1 wherein:

said module is an element of a power conversion and control device adapted to convert AC power to DC power, to convert DC power to DC power of a different voltage, to convert DC power to AC power, or to convert AC power to AC power of a different frequency.

9. The power conversion and control device of claim 8 wherein:

said bus carries currents exceeding 100 Amps.

10. The module of claim 1 wherein:

said heat sink comprises a plurality of metallic spheres thermally and electrically connected to each other and to the interior surfaces of said heat sink housing, such that a spaced lattice structure is formed.

11. The module of claim 9 wherein:

said metallic spheres are silver plated copper balls.

12. The module of claim 1 wherein:

said heat sink comprises a pair of parallel channels, each said channel having an open portion on an upper inner side thereof, such that said heat transfer fluid fills said channels and spills into an interior of said heat sink means, thereby surrounding a heat transfer medium contained in an interior of said heat sink means.

13. The module of claim 1 wherein:

said heat sink comprises an internal element formed by machining a plurality of channels in a solid metallic element.

14. The module of claim 1 wherein:

said heat sink comprises an internal element formed from metal foam.

15. The module of claim 1 wherein:

said heat sink comprises an internal element formed from metal fibers.

16. The module of claim 1 wherein:

said heat sink housing is formed from materials having an electrical resistivity of less than 50 micro-ohm cm at 23°

C. and a thermal conductivity greater than 100 W/m·

°

K at 23°

C.

17. The module of claim 1 wherein:

a mounting surface of said heat sink has a coefficient of thermal expansion between 4.5 and 10 ppm/°

K at 23°

C.

18. The module of claim 17 wherein:

said mounting surface of said heat sink is made from molybdenum.

19. The module of claim 1 wherein:

said heat transfer fluid is a dielectric.

20. The module of claim 19 wherein said heat transfer fluid is the oil used to cool an electric traction motor.

21. The module of claim 1 wherein:

said heat sink is constructed with a flat elongated geometry.

22. The power conversion and control device of claim 8 wherein:

said heat sink means elements are aligned in two rows, each said row including three heat sink elements.

23. The power conversion and control device of claim 8 wherein:

each of said heat sink means elements in each said row is in communication with an adjacent heat sink means element, such that fluid can flow from a first heat sink means element in a row, through a second heat sink means element in said row, and through a third heat sink means element in said row.