Integral heat pipe module

• US 4,833,567 A
• Filed: 10/09/1987
• Issued: 05/23/1989
• Est. Priority Date: 05/30/1986
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Saaski, Elric, Fox, Leslie R., Hannemann, Robert J.
• Primary Examiner(s): Tolin, G. P.
• Application Number:
  US07/107,890
• Time in Patent Office: 592 Days
• Field of Search: 165/185, 165/104.26 X, 165/104.33 X, 165/80.3, 357/82, 174/15 HP, 361/382, 361/385, 361/386, 361/388
• US Class Current: 361/700
• CPC Class Codes: F28D 15/0233 the conduits having a particular shape, e.g. non-circular cross-section, annular F28D15/0241, F28D15/0266 take precedence
• CPC Class Codes: F28D 15/046 characterised by the material or the construction of the capillary structure
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/73253 Bump and layer connectors
• CPC Class Codes: H01L 23/427 Cooling by change of state, e.g. use of heat pipes by liquefied gas H01L23/445

Abstract

An integral heat pipe for transferring heat away from electronic components is disclosed. The heat pipe comprises at least one electronic component mounted to a substrate. A condenser cap is fastened over the substrate to define a sealed pipe chamber around the electronic component. The top of the condenser cap facing the component is a condenser surface and is provided with a number of parallel fluted sections. Each fluted section has parallel vertical sidewalls and a semi-circular top section. A multi-layered fiberous, porous, wick is located between the condenser surface flutes and the top of the electrical component. The top of the component may be provided with a number of parallel grooves exposed to the wick. The pipe chamber is filled with a two-phase working fluid. The heat generated by the electrical component causes the liquid fraction of the working fluid adjacent the component to evaporate. The vapor travels to the fluted condensing surface. The latent heat of vaporization is removed from the vapor so it recondenses and returns to the bottom of the module to repeat the heat transfer cycle. The wick'"'"'s capillary pumping action keeps the fluid distributed over the top surface of the electronic component. The grooved top surface of the electronic component exposed to the wick cause an inverted liquid meniscus to be formed over the component. This causes the liquid adjacent the top of the component to readily evaporate.

Claims

1. An integral heat pipe module for electronic components having at least one component mounted to a substrate, the component having a top surface spaced away from the surface of the substrate, said module comprising:

a. a condenser cap sealingly attached to the substrate over the electronic component so as to define a sealed chamber around the electronic component;

b. a condenser surface under the top of said condenser cap having a surface spaced a selected distance away from the top surface of the electrical component so a continuous thin film of liquid is maintained therebetween, said condenser cap having a plurality of flued sections that extend upward from said surface across the condenser cap; and

c. a sufficient volume of a two-phase, noncorrosive dielectric working fluid having a low-viscosity, high surface tension liquid fraction retained inside said chamber so as to maintain a thin film of liquid working fluid that extends continuously between the top surface of the electronic component and said condenser surface;

said fluted sections of said cap being substantially free of said liquid fraction of working fluid, so that heat transfer by said working fluid from the component is substantially by thin film evaporation.

2. The integral heat pipe module of claim 1 wherein the flues are separated by vertical side walls, and the bottom of the side walls forming said condenser surface spaced from the electronic component.

3. The integral heat pipe module of claim 1 wherein each of the flutes has a top section with semicircular cross-section.

4. The integral heat pipe module of claim 1 wherein the flutes are connected together by at least one cross flute.

5. The integral heat pipe of claim 1 wherein the condenser cap is connected to a heat sink.

6. The integral heat pipe of claim 5 wherein thcondenser cap is provided with at least one external cooling fin, whereby said cooling fin serves as a heat sink.

7. The integral heat pipe of claim 5 wherein the condensor cap is connected to a heat sink by securing a cold plate to the top of the condensor cap.

8. An integral heat pipe module for electronic components having at least one component mounted to a substrate, the component having a top surface spaced away from the surface of the substrate, said module comprising:

a. a condenser cap sealingly attached to the substrate over the electronic component so as to define a sealed chamber around the electronic component;

b. a condenser surface under the top of said condenser cap spaced away from the top surface of the electrical component, so as to define a space therebetween, said surface having a plurality of fluted sections that extend across the condenser surface;

c. a porous wick of sufficient thickness in said chamber between the top of the electrical component and said condenser surface so as to substantially fill the space therebetween; and

d. a sufficient volume of a two-phase, noncorrosive, dielectric working fluid having a low-viscosity, high surface tension liquid fraction retained inside said chamber so said porous wick is saturated with the liquid fraction of working fluid so as to maintain a thin film of liquid working fluid within said porous wick that extends continuously between the top surface of the electronic component and the condenser surface.

9. The integral heat pipe module of claim 8 wherein the flutes are separated by vertical side walls, and the bottom of the side walls form the condenser surface spaced from the electronic component.

10. The integral heat pipe module of claim 8 wherein each of the flutes has a top section with semicircular cross-section.

11. The integral heat pipe module of claim 8 wherein the flutes are connected together by at least one cross flute.

12. The integral heat pipe of claim 8 wherein an evaporator cap having a grooved top surface is attached to the top of the electronic component, and the top of said grooved top surface is in contact with said wick.

13. The integral heat pipe of claim 8 wherein the condenser cap is connected to a heat sink.

14. The integral heat pipe of claim 13 wherein the condenser cap is provided with at least one external cooling fin, whereby said cooling fin serves as a heat sink.

15. The integral heat pipe of claim 13 wherein the condenser cap is connected to a heat sink by securing a cold plate to the top of the condenser cap.

16. The internal heat pipe of claim 8 wherein the wick is composed of multiple layers of fibrous material.

17. The integral heat pipe of claim 8 wherein the wick is formed of a plurality of layers of polyester cloth.

18. The integral heat pipe of claim 16 wherein the wick is composed of woven fibrouus material and the layer in contact with the electronic component has a greater mesh than the layers spaced away from the electronic component.

19. The integral heat pipe of claim 16 wherein the wick is composed of woven fibrous material and the layer in contact with the condenser surface flutes has a coarse mesh than the layers spaced away from the condenser surface flutes.

20. The integral heat pipe of claim 8 wherein the electronic component is provided with a grooved top surface in contact with the wick.

21. The integral heat pipe of claim 12 wherein the electronic component and the evaporator cap are formed of essentially the same material.