Cold Plate

Abstract

A cold plate comprising: a housing having a surface providing a thermal interface for cooling an electronic device; a channel in the housing proximate the surface for liquid coolant to flow through the channel so that heat received by the thermal interface is transferred to the liquid coolant; and a coolant port extending outside the housing for transporting the liquid coolant into and / or out of the channel. A cross-sectional area of ​​an outlet from the coolant port to the channel may be equal to or less than the cross-sectional area of ​​the channel at the outlet. Pins and / or fins may be disposed in the channel adjacent to the coolant port. The coolant port can allow liquid coolant to enter and exit the channel in a direction perpendicular to the surface. The coolant port may include an independent rotary fluid connector, thereby allowing adjustment of the direction of a pipe coupled to the coolant port.

Description

[Technical field]

[0001] The present disclosure relates to cold plates, electronics modules comprising at least one cold plate, and electronics systems comprising a plurality of such electronics modules. [Background technology]

[0002] Within computers, servers, and other equipment used in data processing (called Information Technology or IT) are printed circuit boards (PCBs). On these PCBs are small devices called integrated circuits (ICs) that can include central processing units (CPUs), application specific integrated circuits (ASICs), graphical processing units (GPUs), etc. All of these can be generically referred to as chips.

[0003] IT is usually contained within a case, enclosure, or housing. For example, for a server, this enclosure may be called a server chassis. Server chassis adhere to several industry standards that specify the height of each chassis, usually referred to as 1RU (one rack unit) or 1OU (one open unit), also abbreviated as 1U or 1OU. The smaller of the two main standards is 1RU / 1U, which is 44.45mm or 1.75 inches in height. Such units are sometimes called blade servers.

[0004] Different server products can utilize more than one RU / OU at a time for a chassis, for example a 2U chassis uses two rack units. The size of each server chassis is typically kept to a minimum to maximize the amount of computing power per server rack (the server rack is the main housing to which the server chassis are added).

[0005] Typically, chips used on or in IT are cooled using air. This usually involves some sort of heat sink, with fins or similar placed in contact with the chip surface directly, or with a TIM (thermal interface material) between the two components. In addition to the heat sink, each enclosure uses a series of fans to draw air through the enclosure, remove heat from the heat sink, and expel the heat sink from the chassis.

[0006] In recent years, the peak performance of heat-generating chips has been limited by the limitations of cooling the equipment with air. As technology halves the size for the same performance every few years (Moore's Law), the heat generated by chips increases as the footprint of the components decreases. This also leads to an increase in the size and complexity of heat sinks. This usually means an increase in server chassis size, thus reducing the computing power within a single rack. Summary of the Invention [Problem to be solved by the invention]

[0007] Thus, a more effective method of cooling these heat generating components compared to large air-cooled heat sinks has been sought. Various methods considered include using liquids as coolants. These liquids include dielectric fluids, mineral oil and water, to name a few. Several existing approaches using liquid cooling are known. For example, WO 2018 / 096362, by the same applicant as the present disclosure, describes a submerged liquid cooling approach. Such approaches have high performance and efficiency, but require a special server chassis to hold the liquid coolant. It would be desirable to provide a non-submerged liquid coolant based system with high performance and efficiency. [Means for solving the problem]

[0008] Summary of the Invention Against this background, a cold plate according to claim 1 or claim 2, an electronics module according to claim 25, and an electronics system according to claim 32 are provided.

[0009] In an embodiment, a cold plate is provided having a housing (outer housing) whose surface provides a thermal interface for cooling an electronic device (such as a chip or IC). This surface is typically the bottom surface of the housing. At least one channel is provided in the housing proximate to the surface, and liquid coolant can flow through the channel(s), which may be in series or parallel, and receive heat through the thermal interface. The liquid coolant (which may be water or water-based) enters and exits the channel(s) through one or more coolant ports. The coolant port(s) extend to the outside of the housing, for example perpendicular to the top surface. Beneficially, the cold plate is designed for single phase use, so that the coolant remains essentially liquid during operation.

[0010] In one main aspect, the coolant port comprises an independent rotating fluid connector, such as a swivel joint (which may be a swivel elbow connector, all of these terms are used interchangeably herein), which allows for adjustment of the direction of the pipe coupled to the coolant port. The one or more coolant ports are beneficially on the top surface of the housing. The top surface of the housing can be configured (particularly with respect to its height and / or shape) to allow for adjustment of the direction of the pipe coupled to the coolant port, for example, by having a smaller height around the coolant port than away from the coolant port. If the coolant port has an elbow shape (such that the first portion extends in a direction approximately perpendicular to the top surface and the second portion extends in a direction approximately parallel to the top surface), the height difference may be approximately equal to the bottom of the elbow shape (i.e., where the transition from the first portion to the second portion begins). Preferably, two coolant ports are provided, one (the inlet coolant port) for receiving coolant from outside the cold plate (such as from an external pipe) and providing it to the channel, and one (the outlet or exhaust coolant port) for receiving coolant from the channel(s) and transporting it to the external pipe. Any features described with reference to the coolant ports herein may apply to both coolant ports. The two coolant ports are preferably provided at both ends of the housing, which may be elongated. Pipes, tubes or hoses (preferably flexible) are advantageously coupled to one or more of the coolant ports during operation.

[0011] Advantageously, the swivel joint allows for significant flexibility in the placement and therefore efficiency of the cold plate. By using the swivel joint, the cold plate can be placed in various positions and orientations within the enclosure (such as the server chassis). In this way, a more optimal placement of the cold plate can be provided than would be possible with fixed coolant port(s). Preferably, the swivel joint allows the pipe direction to be adjusted around an axis perpendicular to the top surface of the housing and / or allows for 360 degrees of rotational freedom. In particular, the cold plate can be installed on / in existing hardware pieces in a flexible manner. By rotating the connections, the installer can select the most efficient path for the pipes, tubes or hoses to enter and exit the server chassis. Rotation of the nozzle or connector can help to orient the tubes or hoses around existing components. While the tubes or hoses that connect to the cold plate can be oriented between existing components, rotation on the connector also helps to prevent overly tight bend radii on the tubes. These advantages therefore improve performance and efficiency. Cold plates of various sizes can be used to cool a variety of different chips or heat generating components and can be mechanically attached to a variety of fixed points.

[0012] In another main aspect (which may be combined with the other main aspects or any other aspects), one or more features are provided that can reduce pressure drop and / or provide a low (preferably minimal) pressure drop between piping external to the cold plate and piping within the cold plate.

[0013] In particular, the one or more features include one or more of the following: (a) liquid coolant enters and exits the channel in a direction perpendicular to the thermal interface surface (and / or the bottom surface of the channel, typically the bottom surface proximate the thermal interface surface of the housing); (b) the cross-sectional area of ​​the outlet from the coolant port to the channel is equal to or less than the cross-sectional area of ​​the channel at the outlet (in other words, the flow capacity of the channel is at least as large as the flow capacity of the coolant port outlet to the channel); (c) pins and / or fins are positioned in the channel adjacent to the coolant port (specifically its outlet) so that liquid coolant entering at least one channel flows in all directions in a plane parallel to the surface (and / or the bottom surface of the channel). With respect to (c), the coolant port is positioned relative to the pins and / or fins to promote, for example, an omnidirectional or radial jet flow of liquid coolant. Each of these can promote the flow of coolant in the channel(s), particularly toward the second coolant port (which serves as an external outlet for the cold plate). In this way, pressure drop can be small or minimized.

[0014] All embodiments can attach the cold plate to the heat generating chip or component (electronic device) in the same or similar manner as current air cooled heat sinks, allowing for easy product adaptation to existing hardware by retrofitting the cold plate to the same mounting points.

[0015] In any aspect, the pins and / or fins are advantageously disposed within one or more channels (indeed, in some embodiments, multiple channels may be defined). The pins and / or fins may extend from a bottom surface of the channel, and more preferably to a top surface of the channel (opposite the bottom surface). The pins and / or fins may be disposed within some or all of the channels, particularly around the coolant port(s).

[0016] In a preferred embodiment, the pins and / or fins are arranged in a regular, uniformly distributed pattern and / or to prevent unimpeded flow of liquid coolant between the coolant ports acting as coolant inlets and coolant ports acting as coolant outlets. Such configuration(s) may be provided throughout the entire channel, or such configuration may vary, with such configurations provided around the coolant port(s) and a different configuration of pins and / or fins provided in a middle portion of the channel (e.g., the middle portion of the channel has fins that allow unimpeded flow between the inlet and outlet ports, e.g., using only fins). The channel width of this middle portion of the channel may be smaller than the perimeter of the ports.

[0017] In some embodiments, the pins and / or fins are spaced apart by at least 1 mm to 8 mm, more preferably 3 mm to 5 mm, and most preferably 3.5 mm to 4.5 mm (measured from pin center to pin center). In embodiments, the pins and / or fins are spaced apart by 1.5 (or 2) to 3 times the pin diameter (or fin width), more preferably 2 to 2.5 times the pin diameter (again measured from pin center to pin center). The pin diameter or fin width may be 1 mm to 3 mm, more preferably about 2 mm. Such a configuration may provide a low (or reduced) pressure drop across the cold plate and / or reduce the risk of contamination from liquid-based contaminants and growth.

[0018] In embodiments, heat pipes or vapor chambers may be provided within the housing of the cold plate between the thermal interface surface and the channels, which can increase (or maximize) the effective conduction or diffusion from the central heat flux region of a given chip or IC to the inlet and outlet (exhaust) regions.

[0019] The cold plate may form part of an electronics module, such as a computer system or server, which may include a module housing (such as a server chassis) in which an electronic device is mounted. The electronic device may include one or more chips or ICs mounted, for example, on a PCB (indeed, the electronic device may include part or all of the PCB). The cold plate is mounted to the electronic device such that heat generated by the electronic device is transferred through a thermal interface of the cold plate. The module housing may have an opening such that one or more pipes coupled to coolant ports of the cold plate can pass through the opening, allowing liquid coolant to flow between the interior and exterior of the module housing.

[0020] The module housing is typically substantially planar (e.g., has an elongated rectangular parallelepiped shape) and can define a height dimension (Z) perpendicular to the plane of the housing (typically one rack unit or about 44 mm to 45 mm). The combined size of the electronic device and cold plate in the height dimension typically fills the housing and is typically at least 80%, 85%, 90% or 95% of the size of the module housing in the height dimension. In other words, the Z height of the cold plate assembly when attached to the heat generating components fits within a 1U server chassis (although in some cases larger server chassis may be used). The described cold plates can vary in their overall size. This can depend on the socket type (fixing point) to which they are attached, and the thermal cooling capacity required for the cold plate. The cold plate can function in the same way as an air-cooled heat sink, but typically does not exceed the reduced Z height of the air-cooled heat sink it replaces.

[0021] Multiple electronic devices may be provided inside the module housing (e.g., multiple chips or ICs on the same PCB or on different PCBs). Two or more cold plates may then be used to cool the multiple devices, with each cold plate thermally coupled to at least one electronic device.

[0022] A piping arrangement is preferably coupled to the coolant ports of each cold plate for transferring liquid coolant to and from the respective cold plate. The piping arrangement is preferably configured to transfer liquid coolant to and from the cold plates in series or parallel. It is possible to connect some cold plates in series and other cold plates in parallel in a different arrangement (e.g., a combination of series and parallel couplings). This can be made easier by rotating the coolant ports (using swivel joints).

[0023] An electronic device or server system may also be provided that includes a plurality of electronics modules (e.g., servers), each according to an embodiment described herein. The piping network may be configured to transport liquid coolant to and from each of the electronics modules. A heat exchanger device may then be used to receive liquid coolant from each electronics module via the piping network and transfer heat from the received liquid coolant to at least one heat sink (which may be, for example, air or liquid). The heat exchanger may thereby cool the liquid coolant. The cooled liquid coolant may then be directed to the plurality of electronics modules (e.g., in a closed loop manner). The piping network may transport liquid coolant to and from the plurality of electronics modules in series or parallel (or a combination of series and parallel coupling).

[0024] The electronics modules (particularly if each is a server, e.g., blade servers) can be arranged in one or more racks, preferably multiple racks. Each rack can hold 42 such modules. A single pump can then pump all the liquid coolant in the piping network to all the modules (which can fill multiple racks so that at least 43 modules are provided). Each module can have at least one cold plate (and preferably multiple cold plates) that receives the liquid coolant.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure can be put into practice in a number of ways and preferred embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 illustrates a schematic diagram of one embodiment of a cold plate according to the present disclosure. [Figure 2A] FIG. 2 is a top view of the embodiment of FIG. 1 in a first configuration. [Figure 2B] FIG. 2 is a top view of the embodiment of FIG. 1 in a second configuration. [Figure 3A] 2 is a top view of two coupled cold plates according to the embodiment of FIG. 1 in a first series configuration. [Figure 3B] 2 is a top view of two coupled cold plates according to the embodiment of FIG. 1 in a second series configuration. [Figure 3C] FIG. 2 is a top view of two coupled cold plates according to the embodiment of FIG. 1 in a third series configuration. [Figure 4A] 2 is a top view of two coupled cold plates according to the embodiment of FIG. 1 in a parallel configuration. [Figure 4B] FIG. 2 is a top view of a cold plate according to a first variant of the embodiment of FIG. [Figure 4C] FIG. 2 is a top view of a cold plate according to a second variant of the embodiment of FIG. [Diagram 5] FIG. 1 is a perspective view of an exemplary blade server with a cold plate mounted therein. [Figure 6] FIG. 6 is a side view of the embodiment of FIG. 5. [Figure 7] FIG. 7 shows an enlarged portion of FIG. 6, in which the internal details of the cold plate are shown diagrammatically. [Figure 8A] FIG. 2 is a top inside view of a cold plate according to one embodiment of the present disclosure. [Figure 8B] FIG. 8B is a side view of the embodiment of FIG. 8A. [Figure 9] FIG. 8B shows an enlarged portion of FIG. 8A with further details. [Figure 10A] FIG. 8B is a top internal view of FIG. 8A with further details regarding the coolant flow. [Figure 10B] FIG. 8B is a top internal view of a variation of the embodiment of FIG. 8A with further details regarding coolant flow. [Figure 11A] FIG. 2 is an internal cross-sectional view of a cold plate according to a first further embodiment. [Figure 11B] FIG. 11B is a bottom perspective view of the embodiment of FIG. [Figure 11C] FIG. 11B is a bottom view of the embodiment of FIG. [Figure 12A] FIG. 11 is an internal cross-sectional view of a cold plate according to a second further embodiment. [Figure 12B] FIG. 12B is a bottom perspective view of the embodiment of FIG. 12A. [Figure 12C] FIG. 12B is a bottom view of the embodiment of FIG. 12A. [Figure 13A] FIG. 1 is a schematic diagram of an existing single rack server cooling system. [Figure 13B] FIG. 1 is a schematic diagram of a single rack server cooling system according to the present disclosure. [Figure 14] FIG. 1 is a schematic diagram of a multi-server cooling system according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Referring initially to FIG. 1, one embodiment of a cold plate (or cold plate assembly) according to the present disclosure is shown in schematic form. It is advantageously used in a server blade (or similar module), as described below. The cold plate assembly comprises a cold plate 210 (preferably made integrally), a swivel elbow connection 200, and an inlet / outlet tube 205. Fixation points 215 on the cold plate 210 are also shown. These fixation points advantageously replicate those found in the air-cooled heat sink that the cold plate may replace. The swivel elbow connection (or swivel joint) 200 is particularly useful in configuring the cold plate assembly for operation, as described below.

[0028] The top surface of the cold plate 210 is recessed around the swivel elbow connection 200 such that the height of the cold plate 210 in the recessed area is less than the central portion of the top surface, which allows an additional degree of rotational freedom for the swivel joint 200.

[0029] Referring to Figure 2A, a top view of the embodiment of Figure 1 in a first configuration is shown. The rotation of the swivel elbow connection 200 can be seen, particularly with respect to the recessed portion of the top surface, which has a generally hexagonal shape in plan view. Note that in this example, the inlet and outlet hoses / tubes 205 can traverse the body of the cold plate without interference.

[0030] Referring to Figure 2B, a top view of the embodiment of Figure 1 in a second configuration is shown, where the inlet and outlet hoses / tubes 205 point outward from the cold plate body 210 in any direction. Again, this is made possible by the recessed portion of the top surface as well as the swivel elbow connector 200.

[0031] Thus, generally speaking, the cold plate may be considered to comprise a housing (which may be integrally formed), with a surface (typically planar) of the housing arranged to provide a thermal interface (which may be referred to as a conduction surface) for cooling a thermally coupled electronic device. The cold plate further comprises at least one channel within the housing proximate the surface. The one or more channels may be formed with an internal chamber(s), a volume or other space for containing a liquid coolant (e.g., water, a water-based coolant, a coolant essentially comprising water, or a high specific heat capacity liquid alternative). The one or more channels are arranged such that the liquid coolant flows through the channel such that heat received by the thermal interface is transferred to the liquid coolant. Optionally, multiple parallel channels may be provided, each extending from a coolant port. As further described below, pins and / or fins are preferably arranged within at least one channel.

[0032] The cold plate also comprises a coolant port extending outside the housing for transporting liquid coolant to and / or from at least one channel. The coolant port may be a connector, coupling, joint, or other similar structure. At least one pipe, hose, or tube (preferably flexible) may be coupled to the coolant port for transporting liquid coolant to and / or from the coolant port. Advantageously, the cold plate is configured such that the liquid coolant remains substantially in a liquid state (i.e., single-phase liquid cooling).

[0033] In one aspect of the disclosure, the coolant port includes an independent rotary fluid connector in the form of a swivel joint (or swivel elbow connector, all of which terms are used interchangeably herein), which allows for adjustment of the orientation of the pipe coupled to the coolant port. The independent rotary fluid connector or swivel joint allows for increased flexibility in placement of the cold plate. This allows for the cold plate to be retrofitted to an existing electronic unit, such as a server or other computer system, without the need for other modifications to the unit or system. The cold plate may be configured to fit in place of an air-cooled heat sink, for example.

[0034] Preferably, the surface arranged to provide a thermal interface is the bottom surface of the housing. The coolant port is then advantageously provided on the top surface of the housing opposite the bottom surface. In a preferred embodiment, the coolant port extends in a direction perpendicular to the top surface of the housing (e.g., the first part). The swivel joint can then extend the coolant port in a different direction (e.g., the second part), typically more parallel or nearly parallel to the top surface of the housing. This can for example be referred to as an elbow shape with a curved part between the first and second parts. Preferably, the swivel joint allows the direction of the pipe to be adjusted around an axis perpendicular to the top surface of the housing. In particular, the swivel joint can allow the direction of the pipe to be adjusted by at least 90 degrees, 180 degrees, 270 degrees, preferably up to (and including) 360 degrees, in particular around an axis perpendicular to the top surface of the housing. The swivel connector can thus allow a full rotational freedom of the coolant port.

[0035] The top surface of the housing may be configured (e.g., with respect to its height and / or shape) to allow adjustment of the direction of the pipes coupled to the coolant ports. In particular, the height and / or shape of the top surface may be different from the height and / or shape of other parts of the top surface of the housing (particularly in the case of two coolant ports, the central part of the top surface between the upper coolant ports), thereby allowing adjustment of the direction of the pipes coupled to the coolant ports. In this context, the term height may refer to the distance between the bottom surface and the top surface (in a direction perpendicular to the bottom surface, which is typically a plane). The height difference may reflect the shape and dimensions of the coolant ports, for example, as described below.

[0036] A preferred embodiment has a top surface that is lower in height around the coolant ports than away from the coolant ports. As noted above, if the coolant ports have an elbow shape (such that a first portion extends in a direction approximately perpendicular to the top surface and a second portion extends in a direction approximately parallel to the top surface), the height difference can be approximately the length of the portion of the coolant port that extends from the top surface of the cold plate housing to the base or bottom of the elbow shape.

[0037] In principle, a single coolant port can provide both the inlet and the outlet of liquid coolant to the channels. In a preferred embodiment, multiple coolant ports are used. The coolant port is then a first coolant port for transferring liquid coolant to at least one channel. The cold plate may comprise a second coolant port for transferring liquid coolant from at least one channel. Any feature described herein with respect to a single coolant port may apply to any of the multiple coolant ports. In an embodiment, the housing is elongated and the first and second coolant ports are disposed at opposite ends of the housing along the elongated direction, which may facilitate the flow of liquid coolant across the thermal interface surface and / or aid in flexible positioning of the cold plate. Additionally or alternatively, the second coolant port may comprise a swivel joint (similar to the first coolant port) to allow adjustment of the direction of a pipe coupled to the second coolant port. Providing two coolant ports, each with a swivel joint, can allow for improved methods of joining the cold plates, including the possibility of joining the cold plates to one another.

[0038] Another important advantage of this structure is the ability to use multiple such cold plates together. With reference to FIG. 3A, a top view of two coupled cold plates according to the embodiment of FIG. 1 in a first series configuration is shown. Here, the cold plates are placed horizontally relative to each other, the swivel elbow connection 200 is adjusted accordingly, and a tube / hose 205 connects them both. With reference to FIG. 3B, a top view of two coupled cold plates according to the embodiment of FIG. 1 in a second series configuration is shown. The cold plates are placed vertically relative to each other. The swivel elbow connection 200 allows the tube / hose 205 to bend partway around another swivel connector. With reference to FIG. 3C, a top view of two coupled cold plates according to the embodiment of FIG. 1 in a third series configuration is shown. Here, the cold plates are placed at an angle to each other. The swivel elbow connectors 200 are at a 45 degree angle to each other with a tube / hose 205 connecting them both.

[0039] 4A, which shows a top view of two coupled cold plates according to the parallel configuration or parallel feed embodiment of FIG. 1. The inlets 220a of the cold plates are split to feed the cold plates in parallel. The outlets 220b are split and then merge to feed the cold plates in parallel.

[0040] With reference to the general terms used herein, the electronic device may be a first electronic device and the cold plate may be a first cold plate. Here, a second electronic device may be provided. In that case, a second cold plate (of any type) disclosed herein may be attached to the second electronic device such that heat generated by the second electronic device is transferred through the thermal interface of the second cold plate. A piping arrangement is then advantageously coupled to the coolant port of the first cold plate and the coolant port of the second cold plate for transporting liquid coolant to and from the first cold plate and the second cold plate. In a preferred embodiment, the piping arrangement is configured to transport liquid coolant to and from the first cold plate and the second cold plate in series or parallel.

[0041] The size of the cold plate can be matched to the size of the component or device to be cooled. Referring now to Figure 4B, a top view of a cold plate according to a first variation of the embodiment of Figure 1 is shown. This is a smaller cold plate for cooling smaller components. Referring now to Figure 4C, a top view of a cold plate according to a second variation of the embodiment of Figure 1 is shown. This is a larger cold plate for cooling larger components.

[0042] Reference is now made to FIG. 5, which shows a perspective view of an exemplary blade server with cold plates installed. The same reference numbers are used to indicate the same features as shown in other figures. In this example, a 1RU server chassis 245 is shown with a set of two cold plates 210 on a PCB 240 (motherboard) within the 1RU server chassis 245. On the PCB 240 are other components such as RAM sticks 225 (shown here in a row), capacitors 235 (also shown in a row), and I / O connectors (not shown). As is typical for existing such units, a fan 230 is provided at the rear of the server chassis 245 to remove heat from the chassis 245. I / O 250 is provided at the front of the board. These components could be USB, QSFP, Ethernet ports, etc.

[0043] As can be seen, swivel nozzle 200 on cold plate 210 can be rotated to optimally direct the tubes / hoses around existing components such as RAM 225 and capacitors 235. Inlet and outlet tubes such as shown at 220a and 220b pass through existing openings in server chassis 245, for example PCIE card slots as shown.

[0044]

[0036] Referring now to Figure 6, a side view of the embodiment of Figure 5 is shown. The cold plate is attached to a PCB (e.g., motherboard) 240 on top of the heat generating chips. It is also shown that the cold plate fits within the 1RU server height. The base 265 of the chassis 245 is shown with the PCB 240 attached thereon. The heat generating chips 255 that the cold plate 210 is cooling are on the PCB 240, and between the heat generating chips 255 and the cold plate 210 is a thermal interface material (TIM) 270, such as a gap pad or thermal paste. The distance between the chassis lid 260 and the chassis base 265 is shown as 1RU.

[0045] Referring now to FIG. 7, an enlarged portion of FIG. 6 (specifically the left side thereof) is shown, showing the internal details of the cold plate in cross section and schematic. In this example, the swivel nozzle 200 is attached to the cold plate at the bottom section so that the assembly fits within a 1RU server chassis. The nozzle 200 is pointing above the cold plate for ease of illustration. The pins 275 are provided on the inside of the cold plate, the pins 275 having two different height portions. The pins 275 facilitate heat transfer. The height of the pins 275 can be reduced by locating the inlet and exhaust ports at the ends of the cold plate module.

[0046] Thus, another generalized aspect of the present disclosure may consider an electronics module (e.g., a computer and / or server module or unit, e.g., a server blade). The electronics module comprises a module housing (e.g., a server chassis), an electronic device (e.g., which may comprise one or more chips or ICs mounted on a PCB, e.g., part of a computer server) mounted within the module housing, and a cold plate as disclosed herein mounted to the electronic device. In this manner, heat generated by the electronic device may be transferred through the thermal interface of the cold plate. When the electronic device is mounted on the PCB, the cold plate may also be attached to the PCB (e.g., using screws, bolts, or similar fasteners) for structural and / or thermal connection between the thermal interface side of the cold plate and the heat dissipation side of the electronic device.

[0047] Preferably, pipes (or tubes or hoses) are coupled to the coolant ports of the cold plate to transport liquid coolant to and / or from the coolant ports. In a preferred embodiment, the module housing includes openings (e.g., to allow interface or wire-based communication with electronic devices or auxiliary components, such as daughter card slots or peripheral connection openings). Pipes can then pass through the openings to allow liquid coolant to flow outside the module housing as well as inside the module housing (but typically only within the pipes and cold plate).

[0048] The cold plate typically fits within a standard module housing, particularly such a server chassis. The module housing may be substantially planar (e.g., in the case of a server blade). In that case, the module housing may define a height dimension perpendicular to the plane of the housing, for example, one rack unit (44 mm to 45 mm, more specifically, about 44.45 mm or 1.75 inches). The combined size of the electronic device and cold plate in the height dimension is advantageously at least 80% (or 85%, 90% or 95%) of the size of the module housing in the height dimension.

[0049] In a preferred embodiment, a second electronic device is mounted within the module housing and a second cold plate (of any type disclosed herein) is attached to the second electronic device such that heat generated by the second electronic device is transferred through the thermal interface of the second cold plate.

[0050] Other aspects of the cold plate according to the present disclosure will now be described. In particular, aspects in which the cold plate provides low back pressure are considered. Referring to FIG. 8A, a top internal (plan) view of an exemplary cold plate according to one embodiment of the present disclosure is shown. In this view, the lid and nozzle have been removed for clarity. The first feature identified to reduce back pressure is to provide the cold plate with inlet and exhaust ports perpendicular to its bottom and / or top surface. This has been found to increase (and potentially maximize) omnidirectional flow in the inlet and exhaust regions of the cold plate's internal volume (channels).

[0051] Shown in Figure 8A are coolant inlet ports 104, liquid coolant outlet or exhaust ports 105, coolant flow channels 106, and pins 109. This configuration distributes the coolant flow 106 in all directions, allowing the coolant to spread evenly across the cold plate. In existing cold plates, the coolant is distributed through channels and baffles, increasing the pressure drop.

[0052] A second feature that reduces backpressure is the alignment of the inlet ports 104 and exhaust ports 105 on an internal pin / fin arrangement 109. This can also promote omnidirectional or radial jetting flow 106 at the fluid inlet and outlet exhaust points within the cold plate module.

[0053] Referring to Figure 8B, there is shown a side (cross-sectional) view of the embodiment of Figure 8A, including the nozzle 108, cold plate base 111, and cold plate lid 112. This illustrates a third advantageous feature of the embodiment, in that the cross-sectional area 107 between the outlet of the nozzle 108 and the cold plate base 111 is equal to or greater than the cross-sectional area of ​​the nozzle 108 and hose. The effect of this is to maximize the effective cross-sectional area for low (or minimized) pressure drop.

[0054] A fourth advantageous feature is also shown in which the pins 109 are connected to the base 111 and the lid 112. This ensures that the flow 106 does not have to shortcut or bypass the pins 109. In this way, the pins 109 can direct the coolant flow 106 within the cold plate, as described below.

[0055] Referring now to FIG. 9, an enlarged portion of FIG. 8A is shown with further details. This shows a fifth advantageous feature in which the pins (and / or fins) 109 are non-directional, allowing natural radial flow from the perpendicular inlet and exhaust ports. It also shows a sixth advantageous feature in which there is no line of sight through the pins, as shown by flow lines 110. This can promote non-linear flow and / or promote radial flow. This may also reduce pressure drop. For example, the pins may be formed in offset columns or tessellated triangular spacing. In such a configuration, the angles of the triangles formed between the centers of three adjacent pins (two in one row and the third in an adjacent parallel row in the intervening column) may each be 60 degrees.

[0056] A seventh advantageous feature may also be inferred from this drawing, specifically the spacing between the pins and / or fins 109 may be set to promote coolant flow and reduce the risk of contamination and growth by liquid-side contaminants. Such a gap or spacing may thereby reduce (or minimize) the pressure drop across the cold plate while still promoting radial flow and providing low thermal resistance (and thereby promoting heat transfer). Spacing (measured between pin or fin centres) of 1.5 (or 1.75) to 3 times the pin or fin diameter, more preferably 2 to 2.5 times the pin diameter, has been found to be advantageous. In embodiments, pin or fin diameters of 1.5 mm to 3 mm (more typically around 2 mm) have been used. In practice, the gap between pins (measured from pin edge or flat to adjacent pin edge or flat) may be 1 mm to 4 mm, or more preferably 1.75 mm or 2 mm to 3 mm, especially for pins having a diameter of 2 mm to 2.3 mm. It is noted that the pins do not have to be circular in cross section. For example, they may have a hexagonal cross section.

[0057] The seven advantageous features and synergistic benefits can be seen through the combination of more than one of these advantageous features, which can be used individually or in any combination.

[0058] Thus, a further generalized aspect of the present disclosure can contemplate any type of cold plate disclosed herein having a configuration that provides a low pressure drop. In an embodiment, the coolant ports are configured to direct liquid coolant into and out of at least one channel in a direction perpendicular to the surface, or the coolant ports are positioned relative to the pins and / or fins to promote omnidirectional or radial jet flow of liquid coolant.

[0059] An embodiment may define that a cross-sectional area of ​​the outlet from the coolant port to the at least one channel is less than or equal to a cross-sectional area of ​​the at least one channel at the outlet.

[0060] Some embodiments may include pins and / or fins disposed within at least one channel adjacent to the coolant port such that liquid coolant entering the at least one channel flows in all directions in a plane parallel to the surface.

[0061] In an embodiment, the pins and / or fins are configured to extend from a bottom surface of at least one channel proximate a surface of the housing configured to provide a thermal interface. Preferably, the pins and / or fins are configured to extend to a top surface of at least one channel distal to a surface of the housing configured to provide a thermal interface.

[0062] When multiple coolant ports are provided, the pins and / or fins are advantageously located in at least one channel at least adjacent to the first coolant port and / or the second coolant port. In such regions, the pins and / or fins may be arranged in a regular, evenly distributed pattern and / or to prevent unimpeded flow of liquid coolant between the coolant port and the second coolant port. For example, rows of offset, evenly spaced pins may be provided.

[0063] In certain embodiments, the pins and / or fins are arranged in a regular, uniformly distributed pattern throughout at least one channel. Alternatively, the pins and / or fins may be arranged in a first pattern in a first portion of at least one channel adjacent to the first and / or second coolant ports. The pins and / or fins may then be arranged in a second, different pattern in a second portion of at least one channel, spaced apart from the first and / or second coolant ports. For example, the first pattern may be comprised of pins and the second pattern may be comprised of fins. The channel (which may be defined by its internal volume, without considering the pins or fins) may be wider in the first portion than in the second portion. Optionally, the first pattern is configured to prevent unimpeded flow of liquid coolant between the first and second coolant ports, and the second pattern is configured to allow unimpeded flow of liquid coolant between the first and second coolant ports (e.g., by using linearly configured or straight fins). A first portion of the at least one channel may be adjacent to the first coolant port, and the pins and / or fins may also be arranged in the first pattern (or a pattern having a similar effect) in a third portion of the at least one channel adjacent to the second coolant port, and the second portion of the at least one channel may be between the first and third portions.

[0064] Certain embodiments may provide pins and / or fins spaced apart by at least 1.75 or 2 times the pin diameter or fin width (measured from the center of the pin or fin to the center of an adjacent pin or fin), and up to 2.5 or 3 times the pin diameter or fin width. For example, the gap between pins (measured from pin edge to adjacent pin edge) may be 1.5 mm to 4 mm, or more preferably 2 mm to 3 mm, for pins having a diameter of 2 mm. Such spacing may facilitate coolant flow and reduce the risk of contamination and growth from liquid-side contaminants.

[0065] Referring to Figure 10A, a (plan) top internal view of Figure 8A is shown with further details regarding the coolant flow. As can be seen, the pin / fin arrangement within the cold plate module in the area of ​​the inlet and exhaust ports allows the flow to exhaust radially (i.e., providing omnidirectional flow) 106. This can be attributed to the regular offset pin arrangement, as discussed above. However, more linear and parallel flow regions 113 are seen in the more central areas within the cold plate module.

[0066] Because the flow in the central region is more linear, variations in geometry within this region can be accommodated without compromising performance. Referring to Figure 10B, a top internal view of a variation of the embodiment of Figure 8A with further details regarding the coolant flow is shown. Here, fins 114 are provided in a more central, linear and / or parallel flow region.

[0067] The base of the cold plate may be reinforced to promote heat transfer and improve performance. Referring to Fig. 11A, an internal cross-sectional view of a cold plate according to a first further embodiment is shown, referring to Fig. 11B, a bottom perspective (isometric) view of the embodiment of Fig. 11A is shown, and referring to Fig. 11C, a bottom (base) view of the embodiment of Fig. 11A is shown. In this design, a buried vapor chamber 115 is shown to increase the effective conduction or diffusion from the central heat flux region of a given chip to the inlet and exhaust regions.

[0068] Referring to Figure 12A, an internal cross-sectional view of a cold plate according to a second further embodiment is shown, referring to Figure 12B, a bottom perspective (isometric) view of the embodiment of Figure 12A is shown, and referring to Figure 12C, a bottom (base) view of the embodiment of Figure 12A is shown, where embedded heat pipes 116 are shown as an alternative method of increasing the effective conduction or diffusion from the central heat flux region of a given chip to the inlet and exhaust regions.

[0069] Generally speaking, the cold plate may be considered to optionally further comprise a heat pipe or vapor chamber (advantageously within the housing) between the surface arranged to provide a thermal interface and the at least one channel, which may facilitate heat transfer across the thermal interface.

[0070] The advantages of low pressure drop will now be considered in more detail with reference to FIG. 13A, which shows a schematic diagram of an existing single rack server cooling system. The system includes a server chassis 300, a cold plate 320, a water-based cooling loop 330, a manifold 340, a cooling distribution unit (CDU) 350, and a heat sink 380. The server chassis may be mounted in a rack 310, and a manifold 340 is used to direct coolant to and from other servers (not shown). In such existing designs, multiple pumps are provided. A separate pump is provided in the cold plate 320 (i.e., a pump at the height of the cold plate 320) that can help distribute the coolant. A manifold level pump 335 is also provided in many such designs. In addition, a facility level pump 370 is used. The use of necessary local pumps is required to distribute the coolant due to the large pressure drop in each cold plate. Such designs, where the facility level pump 370 is in the CDU 350, can also be described as a rack level CDU. The CDU 350 includes a heat exchanger 360 for transferring heat to a heat sink 380. The heat sink 380 may be liquid-based or air-based depending on the installation, such as a further coolant loop with a heat rejection unit.

[0071] There are various drawbacks to using multiple pumps in this manner. These include: Multiple pumps increase cost (in some examples, there may be four integrated cold plate pumps per server chassis); Each pump is a potential failure point; Each pump has a power consumption, increasing total power consumption; Each pump must communicate to balance flow across the system, which adds complexity; A facility level pump 370 is still required to circulate the facility coolant; Pump redundancy can only be added at the manifold level pumps 335 or cold plate 320 level.

[0072] By reducing the pressure drop across each cold plate, the number of pumps can be significantly reduced with associated advantages. Referring to FIG. 13B, a schematic diagram of a single rack server cooling system according to the present disclosure is shown. Where the same features as in FIG. 13A are shown, the same reference numbers are used. According to the present disclosure, a cold plate 390 is provided that has a smaller pressure drop. In this case, only a facility level pump 370 is used to distribute coolant to all cold plates 390 in the rack 310. Advantages include: All of the coolant is circulated by a single facility level pump, typically in the CDU 350, without the need for additional pumps for normal operation (although this is not required). The flow rate of the coolant can be balanced through the design of the manifold 340. To add pump redundancy to the facility cooling loop, only one additional pump is required, which does not need to operate during normal use. Further advantages will be appreciated in light of the above considerations.

[0073] 14 is a schematic diagram of a multi-server cooling system according to the present disclosure. It shows a server chassis 400 shown for each rack 410, where multiple such racks 410 are provided, each of which can accommodate up to 42 server chassis 400. A water-based cooling loop 430 is provided across all the racks using a single CDU 450. The CDU 450 includes a heat exchanger 460 and a facility level pump 470, where heat is transferred to a heat sink 480. Thus, a single pump 470 can be used in a system with hundreds of server chassis 400.

[0074] In summary, a series of benefits are provided by the embodiments according to the present disclosure. These are particularly advantageous in cold plates for electronics cooling in high density applications (e.g., 1U size servers in multiple racks) and ultra-high density applications. Having inlet and exhaust ports perpendicular to the cold plate module can maximize omnidirectional flow in the inlet and exhaust regions. Locating the inlet and exhaust ports at the ends of the cold plate module can reduce the height of the pins or fins required. Aligning the inlet and exhaust ports over the pin / fin arrangement can promote omnidirectional or radial jet flow at the fluid inlet and outlet exhaust points in the cold plate module (increasing or maximizing the effective cross-sectional area and / or reducing the exhaust pressure drop of the inlet and exhaust). Providing pin / fin configurations at the inlet and exhaust regions in the cold plate can radially exhaust the coolant flow in linear and parallel flow regions toward the center of the cold plate. Providing a large pin / fin effective gap or spacing can reduce the risk of contamination and growth from liquid side contaminants. The use of a reinforced base for a cold plate with embedded heat pipes or vapor chambers increases (or maximizes) the effective conduction or diffusion from the central heat flux region of a given chip to the inlet and exhaust regions.

[0075] In yet a further aspect of the present disclosure, an electronics system may be considered that includes one or more electronics modules (such as blade servers or other computing units), preferably each of which is according to the present disclosure. In a preferred embodiment, the multiple electronics modules are arranged in multiple racks, each rack being capable of holding up to 42 electronics modules, optionally. The piping network may be configured to transfer liquid coolant to and from each of the electronics modules. The heat exchanger device is then advantageously configured to receive liquid coolant from each of the electronics modules via the piping network and transfer heat from the received liquid coolant to at least one heat sink. This allows the liquid coolant to be cooled. The cooled liquid coolant may then be directed (back) to the multiple electronics modules. In other words, a closed loop may be provided for the liquid coolant across the multiple cold plates. The piping network may be configured to transfer liquid coolant to and from the multiple electronics modules in series or (more preferably) in parallel. Advantageously, a single pump may be configured to pump all the liquid coolant in the piping network (not necessary for normal operation, but redundancy may be provided). The pump can supply liquid coolant (without other pumps in the system) to a large number of electronics modules, e.g., at least 20, 40, 43 (i.e., two racks with at least one of them full), 50, 100, 150, 200 or more. Such advantages may be possible through the use of a cold plate according to the present disclosure.

[0076] Additional aspects of the disclosure may include a method of installing a cold plate according to the present disclosure in an (already functioning) electronics module (such as a server). For example, the method may include fastening the cold plate to one or more electronics in the electronics module. In one embodiment, this may include fastening the cold plate in place of an air-cooled heat sink or replacing the air-cooled heat sink with the cold plate. In yet an additional aspect, a method of operating an electronics system comprising multiple electronics modules each having at least one cold plate may be provided. The method may include pumping liquid coolant through multiple cold plates (in the same and / or different electronics modules) to cool one or more electronics in each electronics module. Method steps (related to providing, installing, configuring, arranging, using, operating, or the like) corresponding to any apparatus or structural feature disclosed herein may also be considered.

[0077] While specific embodiments have been described herein, those skilled in the art will appreciate that various modifications and variations are possible. For example, the construction and / or design of the cold plate may differ from that shown. Other shapes and applications are possible. For example, a stepped bottom (thermal interface) surface (having multiple parallel flat surfaces) could be used, although flat surfaces are preferred.

[0078] All of the features disclosed herein may be combined in any combination, except combinations in which at least some of such features and / or steps are mutually exclusive. In particular, the preferred features of the invention are applicable to all aspects of the invention and may be used in any combination. Similarly, features described in non-essential combinations may be used separately (not in combination).

Claims

1. A cold plate comprising: a housing, a surface of the housing arranged to provide a thermal interface for cooling an electronic device thermally coupled to the housing; at least one channel within the housing proximate the surface, the at least one channel configured for liquid coolant to flow through the channel such that heat received by the thermal interface is transferred to the liquid coolant; a first coolant port for transporting liquid coolant into the at least one channel and a second coolant port for transporting liquid coolant from the at least one channel, wherein pins and / or fins are arranged within the at least one channel such that the liquid coolant entering the at least one channel flows in all directions within a plane parallel to the surface, the pins and / or fins being at least adjacent to the first coolant port and / or the second coolant port but not located underneath the first coolant port and / or the second coolant port; (a) a cross-sectional area of ​​an outlet from the first coolant port to the at least one channel is less than or equal to a cross-sectional area between the outlet and a bottom surface of the at least one channel proximate the surface of the housing configured to provide the thermal interface; (b) the first coolant port is configured to introduce liquid coolant into the at least one channel in a direction perpendicular to the surface, and the second coolant port is configured to extract liquid coolant from the at least one channel in a direction perpendicular to the surface. (c) the pins and / or fins are arranged in a regular, uniformly distributed pattern within the at least one channel adjacent the first and / or second coolant ports and / or to prevent unimpeded flow of liquid coolant between the first and second coolant ports; (d) the pins and / or fins are arranged in a first pattern in a first portion of the at least one channel adjacent the first and / or second coolant ports and in a second, different pattern in a second portion of the at least one channel spaced from the first and / or second coolant ports. Cold plate.

2. A cold plate as described in claim 1, wherein the pins and / or fins are spaced apart by at least 1.5 times the diameter of the pin or the width of the fin.

3. 3. The cold plate of claim 1, wherein the pins and / or fins are configured to extend from a bottom surface of the at least one channel proximate the surface of the housing configured to provide the thermal interface to a top surface of the at least one channel distal to the surface of the housing configured to provide the thermal interface.

4. The cold plate of claim 1 or 2, wherein a width of the at least one channel in the first portion is greater than a width of the at least one channel in the second portion.

5. 3. The cold plate of claim 1, wherein the first pattern is configured to prevent unobstructed flow of liquid coolant between the first and second coolant ports and the second pattern is configured to allow unobstructed flow of liquid coolant between the first and second coolant ports.

6. 3. The cold plate of claim 1, wherein the first portion of the at least one channel is adjacent to the first coolant port, the pins and / or fins are arranged in the first pattern in a third portion of the at least one channel adjacent to the second coolant port, and the second portion of the at least one channel is between the first and third portions.

7. A cold plate as described in claim 1 or 2, wherein the first coolant port has an independent rotating fluid connector, thereby enabling adjustment of the direction of a pipe coupled to the first coolant port.

8. A cold plate as described in claim 1 or 2, wherein the second coolant port has an independent rotating fluid connector thereby allowing adjustment of the direction of a pipe coupled to the second coolant port.

9. A cold plate as described in claim 1 or 2, wherein the housing is elongated and the first coolant port and the second coolant port are arranged at either end of the housing along the elongated direction.

10. 3. The cold plate of claim 1 or 2, further comprising a heat pipe or vapor chamber within the housing between the surface and the at least one channel arranged to provide a thermal interface.

11. The cold plate of claim 1 or 2, wherein the at least one channel comprises a plurality of parallel channels, each of the parallel channels extending from the first coolant port.

12. The cold plate of claim 1 or 2, wherein the cold plate is configured such that the liquid coolant remains substantially in a liquid state.

13. A cold plate as described in claim 1 or 2, further comprising a flexible pipe coupled to the first coolant port for transporting liquid coolant and / or a flexible pipe coupled to the second coolant port for transporting liquid coolant from the second coolant port.

14. 1. An electronic device module, comprising: A module housing; an electronic device mounted within the module housing; 3. An electronic device module comprising: a cold plate according to claim 1 or 2 attached to the electronic device such that heat generated by the electronic device is transferred through the thermal interface of the cold plate.

15. The cooling system further comprises a pipe coupled to the first coolant port for transporting liquid coolant and / or a pipe coupled to the second coolant port for transporting liquid coolant from the second coolant port; The electronics module of claim 14 , wherein the module housing includes an opening, the pipe passing through the opening to allow liquid coolant to flow outside the module housing.

16. 15. The electronics module of claim 14, wherein the module housing is substantially planar and defines a height dimension perpendicular to the plane of the housing, and wherein a combined size of the electronic device and cold plate in the height dimension is at least 80% of a size of the module housing in the height dimension.

17. The electronics module of claim 16 , wherein the size of the module housing in the height dimension is one rack unit.

18. the electronic device is a first electronic device, the cold plate is a first cold plate, and the electronics module comprises: a second electronic device mounted within the module housing; and 15. The electronics module of claim 14, further comprising: a second cold plate of claim 1 or 2 attached to the second electronic device such that heat generated by the second electronic device is transferred through the thermal interface of the second cold plate.

19. a piping system coupled to the first or second coolant port of the first cold plate and the first or second coolant port of the second cold plate for transporting liquid coolant to and from the first cold plate and the second cold plate; The electronics module of claim 18 , wherein the piping system is configured to transport liquid coolant to and from the first cold plate and to and from the second cold plate in series or parallel.

20. The electronics module of claim 14 , wherein the electronic device is at least a portion of a computer server, such that the electronics module is a computer server module.

21. An electronic device system, comprising: a plurality of electronics modules, each of which is according to claim 14; a piping network configured to transport liquid coolant to and from each of the electronics modules; a heat exchanger device configured to receive liquid coolant from each of the electronics modules via the piping network, transfer heat from the received liquid coolant to at least one heat sink, thereby cooling the liquid coolant, and direct the cooled liquid coolant to the plurality of electronics modules.

22. 22. The electronics system of claim 21, wherein the piping network is configured to transport liquid coolant to and from the plurality of electronics modules in series or parallel.

23. The plurality of electronic equipment modules are arranged in a plurality of racks, and the electronic equipment system comprises:

22. The electronics system of claim 21 further comprising a single pump configured to pump all of the liquid coolant in the piping network.

24. 24. The electronics system of claim 23, wherein the number of electronics modules is at least 43.

25. 22. The electronics system of claim 21, wherein the liquid coolant consists essentially of water.

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