Patent application title: Liquid Cooling System Cold Plate Assembly
Jeremy A. Rice (San Jose, CA, US)
IPC8 Class: AF28F312FI
Class name: Heat exchange conduit within, or conforming to, panel or wall structure opposed plates or shells
Publication date: 2012-07-12
Patent application number: 20120175094
A cold plate assembly consisting of a thermally conductive base component
with an insert having a high thermal transfer characteristic adapted for
contacting the surface of a heat source on one side. The surface of the
base component opposite from the insert is surrounding by a housing
defining an enclosed volume through with a flow of liquid coolant is
directed. Inlet baffles adjacent to a fluid inlet in the housing direct
the incoming flow of liquid coolant towards the surface of the base
component in proximity to the insert, facilitating an efficient transfer
of thermal energy from the heat source to the liquid coolant through the
insert and base component. Optional extensions or fins extending into the
liquid coolant contained in the enclosed volume from the surface of the
base component further facilitate the transfer of thermal energy from the
1. A cold plate assembly for use with a liquid cooling system,
comprising: a base component formed from a material having a first
thermal transfer characteristic and adapted for partial immersion in a
flow of liquid coolant on a first surface; a housing defining an enclosed
volume over said first surface, said housing having a fluid inlet and a
fluid outlet for directing a flow of liquid coolant through said enclosed
volume and in contact with said first surface of said base component; an
insert recessed within a second surface of said base component, opposite
said first surface, and is isolated from said flow of liquid coolant,
said insert composed of a material having a second thermal transfer
characteristic which is greater than said first thermal transfer
characteristic, and which is adapted on at least one surface for
contacting a heat source to facilitate a transfer of heat from said heat
source to said base component; and wherein said housing further includes
an inlet baffle in proximity to said fluid inlet, said inlet baffle
projecting within said enclosed volume from a surface of said housing,
and directing an incoming flow of said liquid coolant towards said first
surface of said base component.
2. The cold plate assembly of claim 1 where said inlet baffle defines a channel.
3. The cold plate assembly of claim 1 wherein said inlet baffle defines a cylindrical guide directed axially towards said first surface of said base component.
4. The cold plate assembly of claim 1 wherein at least one of said base and insert materials is copper.
5. The cold plate assembly of claim 1 wherein at least one of said base and insert materials is aluminum.
6. The cold plate assembly of claim 1 wherein said insert material is copper, wherein said base material is aluminum.
7. The cold plate assembly of claim 1 wherein said insert is coupled to said base component by a bonding, welding, soldering, or brazing means.
8. The cold plate assembly of claim 1 wherein said base component is a molded component.
9. The cold plate assembly of claim 1 further including a mounting clip structure external to said housing, said mounting clip structure securing said base component and said insert in contact with said heat source.
10. The cold plate assembly of claim 1 wherein said base component includes a plurality of protrusions on said first surface adapted for immersion in said flow of liquid coolant within said enclosed volume, said plurality of protrusions providing an increased surface area for an exchange of heat between said fluid transfer component and said flow of liquid coolant.
11. The cold plate assembly of claim 1 wherein said base component includes a plurality of protrusions on said first surface adapted for immersion in said flow of liquid coolant within said enclosed volume, said plurality of protrusions directing a flow of liquid coolant within said enclosed volume.
12. The cold plate assembly of claim 1 wherein said housing is integrally formed with said base component.
CROSS-REFERENCE TO RELATED APPLICATIONS
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
 Not Applicable.
BACKGROUND OF THE INVENTION
 The present invention is related generally to liquid cooling systems adapted for use in cooling heat sources such as integrated circuit components, processors, and memory modules in a computer system, and in particular to a cold plate assembly configured for facilitating efficient heat exchange between the heat source and a directed flow of cooling liquid circulated through a chamber within the assembly.
 Personal computer systems which are design for desktop or under-desk use, and which are typically characterized by a main-board or motherboard housed in a chassis or case, often provide one or more expansion slots into which auxiliary components may be installed. These auxiliary components may include network adapter circuit boards, modems, specialized adapters, and graphics display adapters. These auxiliary components may receive power through the connection to the motherboard, or through additional connections directly to a system power supply contained within the chassis or case. Additional components, such as hard drives, disk drives, media readers, etc. may further be contained within the chassis or case, and coupled to the system power supply and motherboard as needed.
 During operation, the motherboard and various auxiliary components consume power and generate heat. To ensure proper functionality of the computer system, it is necessary to regulate the operating temperatures inside the environment of the chassis or case. Individual integrated circuits, especially memory modules and processors, may generate significant amounts of heat during operation, resulting in localized heat sources or hot spots within the chassis environment. The term "processors", as used herein, and as understood by one of ordinary skill in the art, describes a wide range of components, which may include dedicated graphics processing units, microprocessors, microcontrollers, digital signal processors, and general system processors such as those manufactured and sold by Intel and AMD. Failure to maintain adequate temperature control throughout the chassis environment, and at individual integrated circuits, can significantly degrade the system performance and may eventually lead to component failure.
 Traditionally, a cooling fan is often associated with the system power supply, to circulate air throughout the chassis environment, and to exchange the high temperature internal air with cooler external air. However, as personal computer systems include increasing numbers of individual components and integrated circuits, and applications become more demanding on additional processing components such as graphics display adapters, a system power supply cooling fan may be inadequate to maintain the necessary operating temperatures within the chassis environment.
 Specialized liquid cooling systems are available for some components in a personal computer system. Specialized liquid cooling systems typically provide a liquid coolant circulation pathway, which routes a thermal transfer liquid between a heat exchanger such as a radiator and one or more heat source, such as a CPU, GPU, a memory module, a microprocessor, or transformer. At each heat source, the flow of liquid coolant is passed over a heat transfer component, commonly referred to as a cold plate, which is in contact with the heat source on one side, and the flow of liquid coolant on another side. Typically, a cold plate is constructed from a metal, such as copper, which has a good ability to transfer heat from the heat source to the liquid coolant. The surface of the cold plate in contact with the heat source is generally planar, facilitating a large region of contact, while the surface of the cold plate in contact with the liquid coolant flow may have a number of protrusions, fins, or foils extending there from to provide an increased surface area for the exchange of heat.
 Being composed of metal, the cold plate is generally an expensive and heavy component in any liquid cooling system. For some metals, which are ideal heat transfer pathways, the formation of the protrusions, fins, or foils is difficult or time consuming. For example, to form a cold plate from copper, with the necessary protrusions to the required tolerances, a complex sintering process is required which is time consuming and expensive. With other types of metals, such as aluminum, the necessary protrusions may be readily formed at a reduced cost by a direct molding process, but lack the heat transfer characteristics of copper. If the two different types of metals are utilized in combination, it is possible that a galvanic corrosion may occur if each metal is in contact with the liquid coolant, leading to a failure of the liquid cooling system, either through corrosion buildup or leakage of the liquid coolant.
 Specialized liquid cooling systems can additionally suffer from regions of low fluid flow within the fluid chambers coupled to the cold plates, leading to inefficient operations, such as shown in FIG. 4. This can be caused by dispersal of the inflow of liquid coolant within the chamber as it enters the chamber, leading to the formation of "dead zones" within the chamber wherein a flow of the liquid coolant is minimal.
 Accordingly, it would be advantageous to provide a cold plate assembly which is composed of two or more types of metal, which has a reduced manufacturing cost, an in which only a single type of metal is in contact with the liquid coolant, reducing the risk of galvanic corrosion. It would further be advantageous to provide a cold plate assembly with a directed flow of liquid coolant which eliminates or minimizes the formation of "dead zones" within the fluid chamber.
BRIEF SUMMARY OF THE INVENTION
 Briefly stated, the present disclosure provides a dual-metal cold plate assembly for use with a circulating liquid cooling system. The cold plate assembly consists of a base component adapted to receive a high thermal-conductivity insert on a first surface, and for immersion in a flow of liquid coolant on a second surface. The base component may include numerous protrusions, fins, or pins on the surface opposite from the insert for placement into the flow of liquid coolant. The cold plate assembly is fitted to an enclosing housing, such that the flow of liquid coolant is permitted to pass over the base component second surface including any protrusions, fins, or pins, but does not contact any portion of the base. Heat is then transferred from the heat source through the base, into the fluid transfer component, and dissipated into the liquid coolant through the various protrusions, fins, and/or pins which are immersed in the circulating flow of liquid coolant.
 In an embodiment of the present disclosure, the base is formed from a solid copper disk, and the fluid transfer component is formed from molded aluminum, soldered to the base.
 In an alternate embodiment of the present disclosure, a flow of liquid coolant entering the enclosing housing is directed towards the surface of the base component by inlet baffles which define a channel or groove. The directed flow of liquid coolant facilitates efficient transfer of thermal energy from the high thermal-conductivity insert to the base component, and into the flow of liquid coolant for transport away.
 The foregoing features, and advantages set forth in the present disclosure as well as presently preferred embodiments will become more apparent from the reading of the following description in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
 In the accompanying drawings which form part of the specification:
 FIG. 1 is a cross-sectional view of a cold plate assembly of the present disclosure;
 FIG. 2 is a bottom view of the cold plate assembly of FIG. 1;
 FIG. 3 is a cross-sectional view of an alternate configuration of the cold plate assembly of the present disclosure, in which the housing is integrally formed with the fluid transfer component;
 FIG. 4 is a cross-sectional view of a prior art cold plate assembly, wherein the flow of circulating coolant within the housing results in regions of relatively little movement adjacent the base;
 FIG. 5 is a cross-sectional view of an alternate configuration of an integrated housing cold plate assembly of the present disclosure incorporating projecting fluid inlet baffles to direct the flow of circulating coolant within the housing towards the base component surface; and
 FIG. 6 is a cross-sectional view of an embodiment similar to FIG. 5, but with the base and housing formed as separate structures.
 Corresponding reference numerals indicate corresponding parts throughout the several figures of the drawings. It is to be understood that the drawings are for illustrating the concepts set forth in the present disclosure and are not to scale.
DESCRIPTION OF THE PREFERRED EMBODIMENT
 The following detailed description illustrates the invention by way of example and not by way of limitation. The description enables one skilled in the art to make and use the present disclosure, and describes several embodiments, adaptations, variations, alternatives, and uses of the present disclosure, including what is presently believed to be the best mode of carrying out the present disclosure.
 Turning to the Figures, a cold plate assembly 100 of the present invention adapted for secured over a heat source 10 such as an integrated circuit, video or graphic processing unit is shown configured for connection to an existing liquid cooling circulating flow loop via any suitable liquid pathway. The liquid cooling loop, which is not directly part of the present invention, provides all necessary components for circulating a flow of liquid coolant to and from the cold plate assembly 100 through inlets 108A and outlets 108B, thereby drawing heat away from the various heat-generating components 10 in proximity to the cold plate 100.
 Preferably, the cold plate assembly 100 is made from materials which have a high conductivity to facilitate a transfer of heat, such as metals like copper or aluminum. The cold plate assembly 100 consists generally of a medium conductivity base component or fluid transfer component 104 with a high thermal-conductivity insert 102, and a housing 105 which may optionally be integrally formed with the fluid transfer component 104, as seen at FIGS. 3 and 5, or formed as a separate component 105A coupled to the base component 104, as seen at FIGS. 1 and 6. The housing 105, 105a encloses a first surface of the base component within a volume of space or chamber 107 through with a flow of liquid coolant passes via one or more inlets 108A and outlets 108B.
 The insert 102 is inset within a second surface of the base component 104, opposite from the first surface enclosed within the chamber 107. The insert 102 is adapted for placement in contact with the surface of the heat source 10, and preferably consists of a high conductivity material such as copper, which is suitable for contact with the heat source 10. During use, heat is transferred from the heat source 10 through the insert of high conductivity material 102, to the base component 104. The base component 104 in turn transfers the heat or thermal energy to the flow of liquid coolant passing through the enclosing chamber 107.
 The base component 104 may include a plurality of radiating fins 106 or other structures extending from the first surface within the enclosing chamber 107 to provide for an increase in the available surface area over which heat or thermal energy may be transferred to the flow of liquid coolant passing through the chamber 107. The radiating fins 106 may additional function to direct the flow of liquid coolant about a circuitous path through the chamber 107, maximizing heat absorption by the liquid coolant within the chamber 107.
 Preferably, the cold plate assembly 100 is generic in nature, and may be operatively secured in direct contact with any of a variety of different types of heat sources 10, such as processors, memory modules, and graphic display cards, by utilizing an exchangeable mounting clip structure or other attachment means 110. The exchangeable mounting clip structure 110 is configured to facilitate attachment of the cold plate assembly 100 in operative proximity to the particular heat source 10. While the cold plate assembly shown in the figures is generally cylindrical, having a circular base profile when viewed from the bottom as seen in FIG. 2, those of ordinary skill in the art will recognize that the specific shape and dimensions of the cold plate assembly 100, including the shape and dimensions of the base component 104 and insert 102, may be varied depending upon the particular application for which the cold plate assembly 100 is intended to be utilized.
 The high thermal-conductivity insert 102 of the cold plate assembly 100 is preferably a monolithic form of a single metal, such as a copper disk, and may be formed through any conventional manufacturing process to have at least one surface adapted for heat transfer from a heat source 10. A second surface of the insert 102 is configured to be operatively secured or bonded to the base component 104, which is preferably formed from a second metal, such as aluminum. The insert 102 may be secured or bonded to the base component 104 by any suitable attachment means, such as soldering, brazing, or welding, and is preferably seated in a recessed position, flush with the exterior surface of the base component 104.
 By forming the base component 104 and housing 105 from a second metal or heat conductive material which is different from the metal forming the insert 102, the material used to form the base component 104 may be selected based in-part on the ease with which various protrusions, fins, radiator surfaces, or pins 106 may be formed into the surface for immersion in the flow of liquid coolant within the housing chamber 107. For example, the second metal or heat conductive material may be selected to be aluminum, enabling the fluid transfer component 104, housing 105, and associated protrusions, fins, and radiator surfaces 106 to be formed from a molding or casting process. Since only the surfaces of the base component 104 and housing 105 are exposed to the liquid coolant flow, the occurrence of galvanic reactions between the insert 102 and the base component 104 are reduced or eliminated.
 Increased efficiency in the transfer of thermal energy from the heat source 10 to the flow of liquid coolant within the enclosed volume 107 is achieved by positioning the fluid flow inlet 108A in a central location on the housing 105 or 105a, and by imparting a directional flow to the liquid coolant entering the enclosed volume 107, as shown in FIG. 5 which illustrates an alternate embodiment 200 of the cold plate assembly with an integrated housing 105, and FIG. 6 which illustrates a similar alternate embodiment 300 having separate housing 105A. The directional flow is imparted to the liquid coolant by providing an inlet baffle 202 adjacent to the inlet 108A. The inlet baffle 202 projects from a surface of the housing into the enclosed volume 107 and defines a groove or channel within the enclosed volume 107, directing the incoming flow of liquid coolant towards the surface of the base component 104 in proximity to the high thermal conductivity insert 102. The flow of the liquid coolant can be further improved in this region of the enclosed volume by eliminating some or all of the radiating fins 106 from the surface of the base component 104 in proximity to the high thermal conductivity insert 102, allowing for a more even distribution of the incoming fluid flow directed by the inlet baffle 202.
 As various changes could be made in the above constructions without departing from the scope of the disclosure, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
Patent applications by Jeremy A. Rice, San Jose, CA US
Patent applications by ASETEK A/S
Patent applications in class Opposed plates or shells
Patent applications in all subclasses Opposed plates or shells