Thermal management with variable conductance heat pipe

Patent metadata

Field	Value
Publication number	US-11653477-B2
Application number	US-202117221373-A
Country	US
Kind code	B2
Filing date	Apr 2, 2021
Priority date	Jun 29, 2018
Publication date	May 16, 2023
Grant date	May 16, 2023

Abstract

Photonic and electronic integrated circuits can be cooled using variable conductance heat pipes containing a non-condensable gas in addition to a phase-changing working fluid. To package the heat pipe with a subassembly including the integrated circuits in a standard housing providing a heat sink contact area, the heat pipe is oriented, in some embodiments, with its axis between evaporator and condenser ends substantially perpendicular to the direction along which the integrated circuit subassembly is separated from the heat sink contact area, and a portion of the exterior surface of the heat pipe is thermally insulated, with a suitable thermal insulation structure, from the heat sink contact area.

First claim

What is claimed is:

1. A thermally managed optical package comprising:
an optical subassembly comprising a photonic integrated circuit;
a housing surrounding the optical subassembly, a portion of the housing forming a heat sink contact area; and
a variable conductance heat pipe and a thermal insulation structure sandwiched between the optical subassembly and the housing, the variable conductance heat pipe being in thermal contact with the photonic integrated circuit at a first end of the heat pipe and in thermal contact with the heat sink contact area of the housing at a second end of the heat pipe and configured to cool the photonic integrated circuit by heat transfer to the heat sink contact area, the thermal insulation structure insulating an exterior surface portion of the variable conductance heat pipe at the first end from the heat sink contact area of the housing.

2. The optical package of claim 1 , wherein an axis of the heat pipe extending from the first end to the second end is oriented substantially parallel to the heat sink contact area.

3. The optical package of claim 2 , wherein the heat pipe comprises first and second surface portions on mutually opposite sides of the axis in a direction perpendicular to the axis, the photonic integrated circuit placed adjacent the first surface portion, and the thermal insulation structure and the heat sink contact area placed adjacent the second surface portion.

4. The optical package of claim 1 , further comprising a thermal interface structure sandwiched between and in mechanical contact with the photonic integrated circuit and the heat pipe.

5. The optical package of claim 4 , wherein the thermal interface structure is a layered structure comprising a thermally conductive adapter plate in mechanical contact with the heat pipe and a soft thermal interface material layer in mechanical contact with the photonic integrated circuit.

6. The optical package of claim 1 , wherein the optical subassembly further comprises an electronic integrated circuit.

7. The optical package of claim 6 , wherein the variable conductance heat pipe is further in thermal contact with the electronic integrated circuit at the first end of the heat pipe.

8. The optical package of claim 1 , wherein the heat pipe has a thermal conductance that varies by a factor of at least two for temperatures at the second end within a range from 0° C. to 70° C.

9. The optical package of claim 1 , wherein the heat pipe is configured to maintain a temperature at the first end within the range from 20° C. to 85° C. for temperatures at the second end within a range from 0° C. to 70° C.

10. The optical package of claim 1 , wherein the heat pipe contains a working fluid that cools the photonic integrated circuit by evaporation at the first end and that condenses at the second end, and a non-condensable gas that partially blocks, to a varying extent, the working fluid from reaching the second end so as to adjust a thermal conductance of the heat pipe.

11. A heat pipe subassembly for cooling an optical subassembly, the heat pipe subassembly comprising:
a variable conductance heat pipe defining an axis between first and second ends and further defining first and second exterior surface portions on mutually opposite sides of the axis along a direction perpendicular of the axis, the second end operatively in contact with a heat sink contact area extending along the second exterior surface portion of the heat pipe between the first and second ends;
a thermally conductive adapter plate, adhered to the first exterior surface portion at the first end, to operatively provide thermal contact with the optical subassembly; and
a thermal insulation structure interposed between the heat sink contact area and the second exterior surface portion in a region at the first end to operatively insulate that region of the heat pipe from the heat sink contact area.

12. The heat pipe subassembly of claim 11 , wherein the heat pipe comprises:
a wall defining a cavity;
a wick structure lining an interior surface of the wall of the heat pipe; and
a phase-changing working fluid and a non-condensable gas contained within the cavity, wherein the phase-changing working fluid is to operatively cool the optical subassembly by evaporation at the first end and condensation at the second end, and the non-condensable gas is operatively to adjusting the thermal conductance of the heat pipe by at least partially blocking, to a varying extent, the working fluid from reaching the second end.

13. The heat pipe subassembly of claim 11 , wherein the thermally conductive adapter plate is a metal plate soldered to the heat pipe.

14. The heat pipe subassembly of claim 11 , wherein the heat pipe has a thermal conductance that varies by a factor of at least two for temperatures at the second end within a range from 0° C. to 70° C.

15. The heat pipe subassembly of claim 11 , wherein the heat pipe subassembly is configured to maintain a temperature at the first end within a range from 20° C. to 85° C. for temperatures at the second end within a range from 0° C. to 70° C.

16. A method comprising:
extracting heat from an optical subassembly by evaporation of a working fluid contained within a heat pipe that is in thermal contact with the optical subassembly at a first end;
transferring the heat from the first end to a second end of the heat pipe via flow of the evaporated working fluid from the first end to the second end;
transferring the heat from the evaporated working fluid to a heat sink contact area in thermal contact with the heat pipe at the second end to thereby condense the evaporated working fluid, the heat sink contact area extending along the heat pipe between the first and second ends;
transporting the condensed working fluid back to the first end; and
thermally insulating a surface region of the heat pipe at the first end from the heat sink contact area by an interposed thermal insulation structure.

17. The method of claim 16 , wherein the condensed working fluid is transported back to the first end in a wick structure lining an interior surface of the heat pipe.

18. The method of claim 16 , further comprising adjusting a thermal conductance of the heat pipe by variable compression of a non-condensable gas contained in the heat pipe at the second end, the variable compression depending on a vapor pressure of the evaporated working fluid and causing a corresponding variable extent of blocking the evaporated working fluid from reaching a region in thermal contact with the heat sink contact area.

19. The method of claim 18 , wherein the thermal conductance is adjusted to keep a lower limit of a temperature range associated with an evaporator region at the first end of the heat pipe at least 15° C. above a lower limit of a temperature range associated with a condenser region at the second end of the heat pipe.

20. The method of claim 18 , wherein the thermal conductance varies by a factor of at least two for temperatures at the second end within a range from 0° C. to 70° C.

Assignees

• Juniper Networks Inc

Inventors

• Marcoccia Roberto
• Koch Brian Robert
• Schmidt Theodore J
• Wyland Christopher Paul
• Guzzon Robert S
• Fish Gregory Alan

Classifications

• H05K7/20336 Primary

  Heat pipes, e.g. wicks or capillary pumps · CPC title

• F28D15/0275

  Arrangements for coupling heat-pipes together or with other structures, e.g. with base blocks; Heat pipe cores · CPC title

• F28D15/06

  Control arrangements therefor · CPC title

• H05K7/20836

  Thermal management, e.g. server temperature control · CPC title

• G02B6/4268 Primary

  Cooling (of instruments G12B15/00; of electric apparatus H05K7/20; of semiconductor devices H10W76/47) · CPC title