Pressure controllable encapsulated liquid thermal interface

Patent metadata

Field	Value
Publication number	US-11545415-B2
Application number	US-201916716367-A
Country	US
Kind code	B2
Filing date	Dec 16, 2019
Priority date	Dec 16, 2019
Publication date	Jan 3, 2023
Grant date	Jan 3, 2023

Abstract

Heat is transferred to a cold plate from one or more subassemblies in an array of subassemblies in an electronic package. The cold plate has a thermally conductive cold plate substrate, a pressure header, a pressure passage, and one or more pressure connections. Each of the pressure connections connects through a housing opening to housing volume defined by a flexible housing in an encapsulated liquid thermal interface (LTI). The flexible housing is in physical and thermal contact with one of the subassemblies through a housing bottom and a top surface of one or more components in the subassembly. A thermally conductive fluid fills the housing volume, housing opening, pressure connections, pressure passage, and pressure header which are all in fluid communication along with one or more other connections, housing openings, and LTIs on other subassemblies. The system transfers heat from the subassemblies to the cold plate while maintaining a constant pressure/stress on each of the subassemblies. The system pressure on each of the subassemblies is equal. The system pressure can be controlled to a preloaded pressure to insure good electrical contact between components. Shear on the subassemblies is minimized by the LTIs.

First claim

We claim:

1. A cold plate used to cool an electronic package, the electronic package having one or more subassemblies, the cold plate comprising:
a thermally conductive cold plate substrate;
a pressure header within the cold plate substrate;
a pressure passage within the cold plate substrate;
one or more pressure connections being within the cold plate;
an encapsulated liquid thermal interface (LTI) connected to each of the pressure connections, being a respective pressure connection, each of the LTIs having a flexible housing with a housing bottom and the LTI encapsulating an LTI volume;
a hydraulic pressure generating assembly;
a liquid thermal interface (LTI) fluid material filling the pressure header, the pressure passage, each of the respective pressure connections, the LTI volumes, and hydraulic pressure generating assembly,
wherein the pressure header, the pressure passage, each of the respective pressure connections, the LTI volumes and the hydraulic pressure generating assembly are in fluid communication,
wherein the hydraulic pressure generating assembly controls a hydraulic/system pressure transmitted through the LTI fluid material,
wherein each of the housing bottoms is in physical and thermal contact with a top surface of one of the subassemblies,
wherein the flexible housing of the LTI deforms in a vertical direction in response to a stress in the vertical direction and deforms in a horizontal direction in response to a strain in the horizontal direction, and
wherein the housing bottoms cause a constant and equal stress to be maintained on all the subassemblies that minimizes strain on the subassemblies.

2. The cold plate, as in claim 1 , where the LTI fluid material is one or more of the following: a thermal grease, a thermal gel, Mercury, and Gallium combined with Indium.

3. The cold plate, as in claim 1 , where the hydraulic pressure generating assembly comprises:
an assembly bellows that is the pressure header; and
a movable plate that applies a force to the LTI fluid material in the assembly bellows.

4. The cold plate, as in claim 3 , where the force is applied by a manual adjustment and the force creates the hydraulic/system pressure.

5. The cold plate, as in claim 4 , where the manual adjustment comprises:
a chamber;
a spring within the chamber; and
an adjustment plate axially movable within the chamber,

wherein the adjustable plate axially moves within the chamber to apply a force to the spring which in turn applies a force to the movable plate and adjusts the hydraulic/system pressure.

6. The cold plate, as in claim 3 , where the force is applied by an automatic adjustment.

7. The cold plate, as in claim 6 , where the automatic adjustment is controlled by a driver which adjusts the hydraulic/system pressure to a set point pressure determined by a pressure control system.

8. The cold plate, as in claim 1 , where one or more of the LTIs is physically connected to a subassembly in an electronic package so that the LTI controls a pressure and minimizes a shear on the subassembly to which the LTI is physically connected.

9. The cold plate, as in claim 1 , where there are one or more respective subassemblies in an array in the electronic package and where each respective subassembly is physically attached to one of the LTIs, being a respective LTI, the respective LTI controlling a pressure and minimizing a shear on the respective subassembly to which the respective LTI is physically connected and wherein each respective LTI, the pressure connections, the pressure header, and the pressure passage are filled with the liquid thermal interface (LTI) fluid material and wherein the flexible housing of the LTIs is a bellows.

10. The cold plate, as in claim 9 , where the thermally conductive cold plate substrate is made of one or more of the following: a metal, a metal alloy, copper (Cu), aluminum (Al), nickel (Ni), an alloy of Cu, an alloy of Al, and an alloy of Ni.

11. The cold plate, as in claim 9 , where each of the respective LTIs is connected to and is in fluid communication with a respective pressure connection.

12. The cold plate, as in claim 11 , where each respective pressure connection is connected to the pressure passage, the pressure passage being connected to the pressure header, the respective pressure connection, the pressure passage, and the pressure header being within the cold plate substrate.

13. The cold plate, as in claim 12 , where all the respective LTIs, all the respective pressure connections, the pressure passage, and pressure header are in fluid communication and at the hydraulic/system pressure.

14. The cold plate, as in claim 13 , where the hydraulic/system pressure is a preloaded system pressure.

15. The cold plate, as in claim 14 , where the preloaded system pressure is high enough to maintain a minimum pressure to maintain a good electrical connection between each of the respective assemblies and one or more connections on the bottom substrate of the electronic package.

16. The cold plate, as in claim 1 , wherein the pressure generating assembly controls the hydraulic/system pressure to a set point pressure by a pressure control system.

Assignees

• IBM

Inventors

• Sri-Jayantha Sri M
• Mcvicker Gerard

Classifications

• H10W40/772

  Bellows · CPC title

• H10W40/25

  characterised by their materials · CPC title

• H10W40/47 Primary

  by flowing liquids, e.g. forced water cooling · CPC title

• H10W40/70 Primary

  Fillings or auxiliary members in containers or in encapsulations for thermal protection or control · CPC title

• H01L23/473 Primary

  Electricity · mapped topic