Integrated thermal systems

• US 7,692,926 B2
• Filed: 10/31/2007
• Issued: 04/06/2010
• Est. Priority Date: 09/16/2005
• Status: Expired due to Fees

• Current Assignee: University of Cincinnati
• Original Assignee: Progressive Cooling Solutions Incorporated
• Inventors: Medis, Praveen, Parimi, Srinivas, Henderson, H. Thurman, Gerner, Frank M., Shuja, Ahmed
• Primary Examiner(s): DATSKOVSKIY, MICHAIL V
• Application Number:
  US11/932,969
• Publication Number:
  US 20080128898A1
• Time in Patent Office: 888 Days
• Field of Search: 361/679.47, 361/679.52, 361/687, 361699-701, 361715-724, 165/80.4, 165/80.5, 165/104.21, 165/104.26, 165/104.33, 165/185, 257/706, 257714-716, 622/592, 174/15.2, 174/16.3
• US Class Current: 361/701
• CPC Class Codes: F28D 15/043 forming loops, e.g. capillary pumped loops
• CPC Class Codes: H01L 23/427 Cooling by change of state, e.g. use of heat pipes by liquefied gas H01L23/445
• 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 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: Y10S 165/218 Condensor adapted to cover opening at top of vapor generator
• CPC Class Codes: Y10T 29/49396 Condenser, evaporator or vaporizer making

Abstract

The present invention is a MEMS-based two-phase LHP (loop heat pipe) and CPL (capillary pumped loop) using semiconductor grade silicon and microlithographic/anisotropic etching techniques to achieve a planar configuration. The principal working material is silicon (and compatible borosilicate glass where necessary), particularly compatible with the cooling needs for electronic and computer chips and package cooling. The microloop heat pipes (μLHP™) utilize cutting edge microfabrication techniques. The device has no pump or moving parts, and is capable of moving heat at high power densities, using revolutionary coherent porous silicon (CPS) wicks. The CPS wicks minimize packaging thermal mismatch stress and improves strength-to-weight ratio. Also burst-through pressures can be controlled as the diameter of the coherent pores can be controlled on a sub-micron scale. The two phase planar operation provides extremely low specific thermal resistance (20-60 w/cm²). The operation is dependent upon a unique micropatterened CPS wick which contains up to millions per square centimeter of stacked uniform micro-through-capillaries in semiconductor-grade silicon, which serve as the capillary “engine,” as opposed to the stochastic distribution of pores in the typical heat pipe wick. As with all heat pipes, cooling occurs by virtue of the extraction of heat by the latent heat of phase change of the operating fluid into vapor.

Claims

1. An integrated thermal bus system, the system comprising:

one or more heat sources;

an evaporator thermally coupled to at least one of the one or more heat sources;

wherein the evaporator comprises a substrate formed from semiconductor-based material, the substrate comprising;

a porous portion;

a non-porous portion having a contact surface suitable for thermal coupling to the one or more heat sources;

a liquid inlet;

a vapor outlet;

a heat exchange location;

a manifold system that connects the vapor outlet and the liquid inlet to the heat exchange location.

2. The system of claim 1, wherein the one or more heat sources includes semiconductor devices.

3. The system of claim 2, wherein the one or more heat sources includes integrated circuits.

4. The system of claim 1, wherein the heat exchange location includes a condenser.

5. The system of claim 4, wherein the condenser comprises metallic material.

6. The system of claim 1, wherein, the porous portion of the evaporator, comprises coherent porous silicon.

7. The system of claim 1, wherein the heat exchange location includes a radiator.

8. The system of claim 4, wherein, the condensor is air-cooled.

9. The system of claim 4, wherein, the condensor is fluid-cooled.

10. The system of claim 1, wherein the semiconductor-based material comprises crystalline silicon in the [100] direction.

11. The system of claim 1, wherein the semiconductor-based material comprises crystalline silicon that is CMOS-grade n-type silicon.

12. The system of claim 6, wherein the coherent porous silicon comprises pores of a substantially high length to diameter aspect ratio.

13. The system of claim 1, wherein the porous region comprises pores having a length to diameter aspect ratio that is between 60-100.

14. The system of claim 1, wherein the porous region comprises pores having a length to diameter aspect ratio that is between 100-150.

15. The system of claim 1, wherein The porous region comprises pores having a length to diameter aspect ratio that is between 150-250.

16. A thermal bus system integrated in a system having multiple devices, the thermal bus system comprising:

multiple evaporators each attached to one of the multiple devices in the system;

wherein, each of the multiple evaporators includes a substrate formed from semiconductor-based material, the substrate having;

a porous portion;

a non-porous portion;

a. liquid line;

a vapor line;

a heat exchange location; and

a manifold system that connects the vapor outlet and the liquid inlet to the heat exchange location.

17. The system of claim 16, wherein the multiple devices include hot temperature devices.

18. The system of claim 16, wherein the heat exchange location includes a condensor.

19. The system of claim 18, wherein manifold system forms a hermetic seal between the multiple evaporators and the condensor.

20. The system of claim 18, wherein the condenser comprises copper.

21. The system of claim 16, wherein the multiple devices include semiconductor devices.

22. An integrated thermal management system for cooling a semiconductor device, the system comprising:

an evaporator thermally coupled to the semiconductor device;

wherein the evaporator comprises a substrate formed from semiconductor-based material, the substrate comprising;

a porous portion;

wherein, the porous portion of the evaporator, comprises coherent porous silicon;

a nonporous portion having a contact surface suitable for thermal coupling to the one or more heat sources;

a liquid inlet;

a vapor outlet;

a condensor formed from a metallic material;

a manifold system that connects the vapor outlet and the liquid inlet to the condensor;

wherein, when in operation, the semiconductor device increases in temperature and the evaporator operates with the condensor to remove heat from the semiconductor device thus decreasing the temperature of the semiconductor device.