High thermal capacity heat sink

Abstract

A heat sink for cooling a heat generating device, the heat sink comprising: a housing, the housing comprising a heat transfer block for receiving heat from the heat generating device, and a sidewall extending from the heat transfer block, the heat transfer block and the sidewall together defining an interior volume for receiving a coolant from an exterior of the heat sink, and a plurality of heat pipes and / or vapor chambers each extending from the heat transfer block within the interior volume.A cooled electronics system, the cooled electronics system comprising: an electronic device that generates heat in use, the heat being dissipated from the electronic device through an exterior surface of the electronic device, and a heat sink having a heat transfer block attached to the exterior surface of the electronic device.

Description

[Technical field]

[0001] Technical Field of the Disclosure The present disclosure relates to heat sinks and cooled electronic systems comprising the heat sinks. Methods of manufacture and / or operation of the heat sinks and / or cooled electronic systems are also disclosed. [Background technology]

[0002] Background of the disclosure Computers, servers, and other devices used for data processing (known as Information Technology or IT) typically contain Printed Circuit Boards (PCBs). On these PCBs are devices called Integrated Circuits (ICs) that can include Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Graphical Processing Units (GPUs), Random Access Memory (RAMs), and more. All of these electronic components and devices generate heat when in use. To maximize IT performance, heat must be dissipated to keep the contents at an optimal temperature. These considerations also apply to other types of electronic devices or systems.

[0003] Typically, electronic components or devices used 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 either directly or with a Thermal Interface Material (TIM) between the two components. In addition to the heat sink, a series of fans can draw air across the heat sink to move heat away from the electronics. This type of heat sink is used in combination with additional cooling in the facility where the electronics are located (e.g., a server center), such as air conditioning. This cooling method is not particularly efficient, has high running costs, and uses a large amount of space to manage the air used for cooling.

[0004] This method of cooling IT has been used almost exclusively for mass-produced IT and server equipment. However, in recent years, the limitations of cooling equipment with air have reduced the peak performance of heat-generating chips. As technology halves in size every few years for the same performance (as exemplified by Moore's Law), the heat generated by chips increases as the footprint of components decreases.

[0005] In addition to (or as an alternative to) air cooling, a cold plate can be placed adjacent to a high temperature electronic component or device, as described, for example, in WO 03 / 107728. The cold plate is a form of heat sink, in which a coolant flows through the cold plate, thereby carrying away heat. Such a system can be more efficient than cooling approaches that rely solely on air, but at the cost of increased complexity.

[0006] Another method of cooling IT uses immersion (induction to the chip, partial or complete immersion) in a dielectric coolant. WO 2019 / 048864 describes heat sinks and heat sink configurations for use in immersion cooling. A heat sink can be used to collect the dielectric coolant adjacent to the device to be cooled, thereby providing targeted cooling. Such heat sinks can have some similarities to cold plates, except that the coolant may overflow or spill from the heat sink, thereby cooling additional devices in the same outer housing or chassis.

[0007] As the operating temperatures of electronic devices increase, it is desirable to achieve higher efficiency and / or heat transfer capacity of heat sinks (cold plates, heat sinks for dielectric cooling, etc.) for IT and other applications. This represents a significant challenge. Summary of the Invention [Means for solving the problem]

[0008] Disclosure Summary Against this background, a heat sink according to claim 1 and a cooled electronics system according to claim 20 are provided. Further preferred and / or advantageous features are specified in the dependent claims and the remaining disclosure of the present specification. Methods of manufacturing and / or operating such a heat sink or cooled electronics system can also be envisaged, comprising steps corresponding to the structural features described herein.

[0009] A heat sink is provided having heat pipes and / or vapor chambers within an interior volume that also receives a coolant fluid (typically liquid and usually does not change phase). The coolant is usually supplied from the outside of the heat sink and passes through the interior volume before exiting the interior volume. The heat pipes and / or vapor chambers advantageously extend from a heat transfer surface or block in the base of the heat sink. The usually elongated heat pipes and / or vapor chambers carry heat from the base to the top of the interior volume. This facilitates efficient transfer of heat from the heat transfer surface resulting in a high heat capacity.

[0010] In one embodiment, the heat sink has a housing comprising a heat transfer block and a sidewall extending from the heat transfer block. The heat transfer block and the sidewall together define an interior volume. The heat pipes typically each extend substantially parallel to one another. Preferably, the heat pipes and / or vapor chambers extend substantially perpendicular to the plane of the heat transfer block and / or substantially parallel to the sidewall. The heat transfer block may have a substantially flat surface and / or may be substantially flat in shape. This arrangement may allow a high density of heat pipes and / or vapor chambers to conduct from the heat transfer surface.

[0011] Heat sinks are typically tall in that the length of one, some or all of the heat pipes and / or vapor chambers (and thus the sidewalls) is longer than a dimension of the base (i.e., heat transfer surface), such as width, length or diagonal size (if the base has a rectangular or square outline) or radius or diameter (if the base has a polygonal, circular or circular outline).

[0012] In certain embodiments, the housing also has a lid that may be distal to the heat transfer block. If the lid is positioned to seal the interior volume, the heat sink may be referred to as a cold plate. Embodiments without a lid, with a partial lid and / or a lid that does not seal the interior volume may be used for immersion cooling. In such embodiments, the heat sink may be configured to allow coolant to flow out of the interior volume and be used for direct cooling of other devices.

[0013] The heat sink may further comprise a coolant inlet for receiving coolant from the exterior of the heat sink to the internal volume, and a coolant outlet for the coolant to leave the internal volume and be transported to the exterior of the heat sink. Typically, the coolant inlet is close to the heat transfer block and the coolant outlet is distal to the heat transfer block, although this may be reversed in embodiments. When the coolant outlet is closer to the heat transfer block, the coolant outlet may include a pipe that receives the coolant and carries it upwardly away from the heat transfer block. This may facilitate collection of the coolant within the internal volume. Respective portions (e.g., connection ports) of the coolant inlet and / or coolant outlet may be removably coupled to the housing.

[0014] In some implementations, the coolant inlet may be provided in the lid. This arrangement may mean that the coldest coolant enters the interior volume of the heat sink distal to the heat transfer surface, thereby maximizing the temperature difference along the heat pipe and making the heat transfer more efficient. Also, the flow may be balanced so that the flow penetrates the entire length of the heat pipe. The coolant may flow from the coolant inlet to the base and then from the base to the outlet (through the heat pipe and / or vapor chamber). Optionally, the coolant outlet may be provided in the lid. The coolant inlet may be collinear with the heat pipe and / or vapor chamber. This may maximize the contact of the coolant with the surface area of ​​the heat pipe without the need for surface extension fins on the heat pipe. In this case, the coolant inlet is in the center of the lid, which may also allow for a more balanced or more evenly distributed flow of the coolant in the interior volume.

[0015] In cold plate implementations, the manifold can direct coolant from the coolant inlet to multiple locations at the base of the multiple heat pipes and / or vapor chambers. In other words, the manifold can allow the incoming (and therefore coldest) coolant to flow directly to multiple locations at the base of the heat pipes and / or vapor chambers. This can promote efficient flow of coolant and efficient cooling within the cold plate. These locations can be located symmetrically across the base of the heat pipes and / or vapor chambers (and / or in a plane parallel to the heat transfer block, or at least in the surface of the heat transfer block that the heat pipes are proximal to). In some embodiments, the housing can define the manifold, and / or the manifold can be integral with the housing.

[0016] The construction of the housing and / or sidewall may be modular. For example, the sidewall may be formed from modules, each defining a portion of the sidewall. The modules may then be stacked (on the heat transfer block) to define an interior volume.

[0017] Advantageously, the heat pipes and / or vapor chambers are arranged in a regular pattern. This may be particularly applicable when heat pipes are used. In one useful pattern, the angle between the center of each heat pipe and one or more respective adjacent heat pipes is about 60 degrees (e.g., 45 degrees to 75 degrees, 55 degrees to 65 degrees, 57 degrees to 63 degrees, 58 degrees to 62 degrees, or 59 degrees to 61 degrees).

[0018] The heat pipes and / or vapor chambers may all be the same. However, in certain embodiments, the heat pipes and / or vapor chambers are not all the same, and in particular do not have the same cross-sectional size and / or shape (cross-section taken across the major dimension). This may improve the compactness of the heat pipes and / or vapor chambers. For example, the heat pipes and / or vapor chambers may be divided into two sets having different cross-sectional areas (but optionally otherwise the same). The two sets of heat pipes may be spaced apart (or staggered) from each other. This allows for closer spacing of the heat pipes and / or vapor chambers, providing more surface area of ​​the heat pipes and / or vapor chambers within the internal volume. Three or more sets of heat pipes or vapor chambers may be contemplated, with each set having a different cross-sectional area. The cross-sectional shapes of the heat pipes or vapor chambers (e.g. within each set) may be the same or different. Possible cross-sectional shapes include circular, polygonal (particularly rectangular or hexagonal) or fin-shaped (particularly for the vapor chambers). Sets of heat pipes and / or vapor chambers differing only in shape may also be contemplated.

[0019] The transfer of heat to the coolant may be accomplished in different ways. In one embodiment, the heat pipes and / or vapor chambers are soldered or metallurgically bonded into the heat transfer block. Additionally or alternatively, heat may be conducted upwards (i.e., away from the heat transfer block) along the sidewalls between the heat pipes. Each heat pipe and / or vapor chamber may be disposed within a respective hole in the heat transfer block.

[0020] In another embodiment, the heat transfer block may include a vapor chamber (within). More preferably, the heat pipes and / or vapor chamber extending from the heat transfer block may be integral with the vapor chamber of the heat transfer block (i.e., the vapor chamber in the heat transfer block may extend into the heat pipes and / or vapor chamber extending therefrom).

[0021] Each baffle in the interior volume can direct the flow of coolant toward or away from one or more respective heat pipes and / or vapor chambers. Certain implementations use generally planar baffles. These may be distributed vertically (i.e., along a direction away from the heat transfer block) within the interior volume. Adjacent baffles can then cover different portions of the cross-sectional area of ​​the interior volume, for example alternating between different or opposing side walls. This allows the coolant to flow throughout multiple heat pipes and / or vapor chambers. In embodiments, insulation around the exterior of the housing can also help induce heat transfer through the coolant to the heat sink and away from its surroundings.

[0022] The heat sink may be provided as part of a cooling electronic system (e.g., a computing module). An electronic device, such as a computer chip or circuit, may generate heat during use, which is dissipated through an outer surface. A heat transfer block of the heat sink may be mounted on an outer surface of the electronic device, for example, such that an outer surface of the heat transfer block is flush with the outer surface of the electronic device. Heat may be efficiently transferred from the electronic device to a coolant in the heat sink. The system may have a chassis with the electronic device and the heat sink disposed therein.

[0023] The exterior surface of the electronic device has a thermal profile when in use (e.g., certain areas may be hotter and other areas cooler). Optionally, the center of the coolant inlet and / or heat transfer block of the heat sink is aligned with (e.g., directly adjacent to) the hottest portion of the thermal profile.

[0024] In addition to the electronic device being cooled by the heat sink, there may be other electronic devices being cooled within the chassis, and the coolant exiting the heat sink may be directed to flow over one or more other electronic devices, particularly to cool the one or more other electronic devices.

[0025] The heat exchanger can receive coolant from the heat sink and transfer heat from the coolant to the heat sink. The piping arrangement can transport the coolant between the heat exchanger and the heat sink. A pump (e.g., coupled within the piping arrangement) can create a flow of coolant between the heat exchanger and the heat sink. The heat exchanger may be located internal or external to the chassis.

[0026] 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]

[0027] [Figure 1] 1 is an isometric view of a heat sink attached to an electronic device having at least one component to be cooled, according to a first embodiment; [Diagram 2] FIG. 2 is a side view of the embodiment of FIG. 1. [Diagram 3] 3 is a plan cross-sectional view of the embodiment of FIG. 1 taken along section AA shown in FIG. 2. [Figure 4] FIG. 2 is a front view of the embodiment of FIG. 1. [Diagram 5] 5 is a side cross-sectional view of the embodiment of FIG. 1 taken along section BB shown in FIG. 4. [Figure 6]FIG. 2 is an isometric view of only the heat sink from the embodiment of FIG. 1. [Figure 7] FIG. 7 is a plan view of the heat sink of FIG. [Figure 8] FIG. 7 is a side view of the heat sink of FIG. 6. [Figure 9] FIG. 7 is a front view of the heat sink of FIG. [Figure 10] FIG. 7 is an exploded isometric view of the heat sink of FIG. [Figure 11] FIG. 2 is an isometric view of only the electronics components from the embodiment of FIG. 1. [Figure 12] FIG. 12 is a plan view of the electronic component of FIG. [Figure 13] FIG. 12 is a side view of the electronic component of FIG. [Figure 14] FIG. 1 is an isometric view of a heat sink according to a second embodiment. [Figure 15] FIG. 15 is a side view of the embodiment of FIG. [Figure 16] FIG. 15 is an exploded isometric view of the heat sink of FIG. [Figure 17] FIG. 13 is an exploded isometric view of a heat sink according to a third embodiment. [Figure 18] FIG. 18 is a side view of the embodiment of FIG. 17. [Figure 19] 19 is a plan cross-sectional view of the embodiment of FIG. 17 taken along section DD shown in FIG. 18. [Figure 20] FIG. 13 is an exploded isometric view of a heat sink according to a fourth embodiment. [Figure 21] FIG. 21 is a front view of the embodiment of FIG. 20. [Figure 22] 21 is a side cross-sectional view of the embodiment of FIG. 20 taken along section FF shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] All drawings are schematic in nature, and identical elements are shown in different drawings using the same reference numerals.

[0029] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As mentioned above, the present disclosure is described in terms of a generalized heat sink. This can include cold plates, open cold plates (cold plates that allow coolant to flow out of the cold plate), and heat sinks for immersion cooling, as described in WO 2019 / 048864. This may also apply to other types of heat sinks. A heat sink typically comprises a heat transfer block that is flush with a heat source (an electronic device, such as a packaged integrated circuit or a collection of components that can be mounted on a circuit board).

[0030] Within the heat transfer block are fixed heat pipes. The heat pipes are generally oriented perpendicular to the plane of the heat transfer block and / or heat source. This allows for a high density of heat pipes conducting away from the footprint of the heat source. They are typically elongated and may be tall, especially relative to the dimensions of the heat transfer block heat sink surface. Using heat pipes in this way can facilitate significant removal of heat from a small area. For example, 600 W of heat power can be removed from a square planar heat transfer block with heat sink surface dimensions of 55 mm x 55 mm. The heat pipes are arranged in a high density as described below.

[0031] The heat pipes may be soldered or metallurgically bonded into the heat transfer block, which allows the distance between the heat source and the heat pipes to be minimized, while still allowing heat to be conducted along the wall between the heat pipes perpendicular to the heat source, and through the less efficient crimped ends of the heat pipes.

[0032] The use of modular housings (segments) can also be beneficial. In particular, different heat pipe lengths can be used for different cooling requirements, or the height of the heat sink housing can be varied with respect to space requirements (e.g., within the outer chassis). In principle, the housings can be stacked to any required height.

[0033] Before describing specific embodiments of a heat sink according to the present disclosure, the present disclosure will first be described in more general terms. From these terms, a heat sink for cooling a heat generating device can be considered, comprising a housing, the housing comprising a heat transfer block for receiving heat from the heat generating device, and a sidewall extending from the heat transfer block, the heat transfer block and the sidewall together defining an interior volume for receiving a coolant from the exterior of the heat sink, and a plurality of (elongated) heat pipes each extending (e.g., parallel) from the heat transfer block within the interior volume. Thus, the heat pipes extend within the interior volume and do not just sit within the heat transfer block. This allows more heat pipes to be placed within the heat sink than previously considered. In some implementations, only a small portion (1%, 2%, 5%, 7.5%, 10% or 15% or less of the length of the heat pipe) may be in contact with the heat transfer block.

[0034] Although the term heat pipe is used here, it is understood that the terms "heat pipe" and "vapor chamber" are often used to describe similar types of devices having different shapes. Heat pipes typically have a pipe-like (or pin-like) shape, while vapor chambers are generally more flattened (e.g., flatter and / or fin-shaped). Additional and / or alternative uses of vapor chambers are discussed further below.

[0035] The sidewall may be formed from a plurality of modules. Each module may then define a portion of the sidewall. For example, the modules may then be stacked on a heat transfer block to define an interior volume. The coolant is typically a liquid (preferably the heat sink is configured to maintain the coolant in this phase). Preferably, a plurality of heat pipes are soldered or metallurgically bonded into the heat transfer block.

[0036] In another aspect, a cooled electronics system may be considered, comprising an electronic device that generates heat during use, where the heat is dissipated from the electronic device through an exterior surface of the electronic device, and a heat sink as disclosed herein, the heat sink having a heat transfer block attached to the exterior surface of the electronic device. For example, the exterior surface of the heat transfer block may be flush with the exterior surface of the electronic device. The system may further comprise a chassis, where the electronic device and the heat sink are typically disposed within the chassis.

[0037] Specific embodiments will now be detailed, and further reference to this generalized sense of the disclosure will be made again below.

[0038] 1-5, a heat sink 100 is shown attached to an electronic device 200 having at least one component to be cooled in accordance with a first embodiment, shown in an isometric view in FIG. 1, a side view in FIG. 2, a plan cross-sectional view in FIG. 3, a front view in FIG. 4 and a side cross-sectional view in FIG. 5.

[0039] The heat sink 100 comprises a base plate 1, a spring arrangement 2, a housing 3, a top plate (lid) 4, and tie bars 5. The heat sink 100 further includes an inlet arrangement 6 and an outlet arrangement 7. Provided within the heat sink 100 are heat pipes 8 and a baffle plate 9 that defines a gap 10, which will be further described below. The heat sink 100 is used for immersion (dielectric) cooling, rather than a cold plate with a closed coolant (water) circuit.

[0040] The housing 3 is made of stacked components. Each component (module or segment) has the same size and shape, and the height of the housing 3 can be set by stacking a certain number of housing components. The housing 3 has a generally rectangular shape, but this is not required. The housing 3 defines an internal volume for collecting coolant, as will be further described below. Thus, the height of the heat sink 100, and more specifically its internal volume, can be changed by using a different number of segments in the housing 3, for example, to accommodate different cooling requirements or space constraints. A typical heat sink is relatively flat and has a height dimension that is usually smaller than its length and / or width. In contrast, the heat sink 100 has a relatively tall shape, with a height dimension (of the housing 3) that is greater than the length and / or width dimensions (and sometimes the diagonal length) of the base plate 1.

[0041] In this embodiment, the segments of the housing 3 are made from plastic. This allows the housing to be thermally (and electrically) insulated and improves thermal performance. In particular, it allows for minimizing heat transfer to the surrounding environment, thereby improving the efficiency of the heat sink. A top plate 4 may be used to add rigidity to the plastic laminate segments of the housing 3. The segments are held together by tie bars 5.

[0042] The electronic device 200 comprises at least one (typically multiple) electronic components, such as packaged integrated circuits. The base plate 1 is attached to the electronic components using a spring arrangement 2 (typically comprising springs and screws) to provide a force to a thermal interface material (TIM, not shown) between the base plate 1 and the electronic device 200. The base plate 1 can therefore be considered as a heat transfer block, as it is configured to receive heat (by conduction) from the electronic device 200. The base plate 1 has a generally planar rectangular or square shape.

[0043] As mentioned above, the heat sink 100 is designed for immersion cooling (particularly using a dielectric), and the heat sink 100 and other components in the same chassis (not shown) as the electronic device 200 are cooled by the same coolant flowing through the heat sink 100. In the illustrated embodiment, the coolant inlet 6 is at the top of the housing 3 and the coolant outlet 7 is at the bottom of the housing 3. The coolant enters through the coolant inlet 6 that is furthest from the heat source, so that the temperature difference along the heat pipe 8 can be maximized. In this case, the outlet 7 includes an upward portion 7A configured to raise the dielectric coolant, thereby overflowing the outlet 7 at the highest possible point (distal to the base plate 1). This is to ensure that the heat sink housing 3 is always filled with coolant. The overflowing dielectric coolant can then cool additional components, for example on the substrate of the electronic device 200 (as described further below).

[0044] With particular reference to FIG. 3, a planar cross-sectional view of the embodiment of FIG. 1 is shown along section AA (shown in FIG. 2). Section AA is cut directly through the housing segment 3 and heat pipes 8. The view shows 49 heat pipes at a 60 degree pitch with 6.8 mm spacing between each heat pipe. The staggered pattern (due to the pitch angle) allows the coolant to spread throughout all of the heat pipes 8. The housing segment 3 is preferably molded on its inside to match the outer shape of the heat pipes 8, preventing the coolant from bypassing the heat pipes. In the illustrated embodiment, the heat pipes 8 all have the same shape and cross-sectional area, although this is not believed to be necessary. It is believed that the cross-sectional shape of the heat pipes 8 provides a high surface contact area for the interface between the coolant fluid and the heat pipes 8 as the flow travels around the circumferential path.

[0045] The pattern shown for the heat pipes 8 is believed to be one of the densest patterns achievable while still maintaining sufficient coolant flow and ensuring sufficient contact area between the coolant and the heat pipes 8. This pattern may also prevent direct flow over the heat pipes 8 and / or straight line fluid flow from inlet 6 to outlet 7. Rather, turbulent flow is created that spreads over all the heat pipes 8, ensuring uniform contact and also stopping the coolant from bypassing any of the heat pipes 8. This configuration is suitable for cooling electronic devices 200 with high heat output. It has been found to have superior thermal performance compared to heat sinks with horizontally oriented heat pipes arranged in a high density. The vertical orientation of the heat pipes 8 in this embodiment (i.e., substantially perpendicular to the base plate 1) allows for the use of a significantly larger number of heat pipes 8. It has been found that a large number of heat pipes is desirable for thermal performance. Orienting the heat pipes horizontally allows for approximately 6 heat pipes compared to 49 heat pipes 8 in the illustrated embodiment.

[0046] Particular reference is also made to FIG. 5, which shows a side cross-sectional view of the embodiment of FIG. 1 along vertical cross section BB (shown in FIG. 4) through the center. This shows the path that the coolant takes across the heat pipes 8 from inlet 6 to outlet 7. It also shows that the heat pipes are attached to the base plate 1 by soldering into holes 12 formed in the base plate 1. The shape of each hole 12 in the base plate 1 matches the shape of the respective heat pipe 8 as closely as possible so that a minimum amount of solder is used. This reduces thermal resistance and potentially improves performance. Another desirable parameter to control is the depth to which each heat pipe 8 is inserted into the base plate 1 (which may be governed by the height of the respective hole 12). Each heat pipe 8 has a thicker metal at the end (tip). Specifically, one end of the heat pipes 8 is pointed (crimped or tapered) and the other end is rounded. The pointed end of the heat pipe 8 is inserted into the hole 12. The depth of each hole 12 can be configured to provide sufficient contact between the heat pipes 8 and the base plate 1 to optimize heat transfer from the base plate 1 to the vapor within the heat pipes 8. The rounded end of each heat pipe 8 is inserted into a respective hole 13 formed in the top plate 4.

[0047] The baffle plates 9 are stacked horizontally along the vertical heat pipes 8. They are advantageously trapped between each segment of the housing 3 for ease of assembly. The baffle plates 9 form horizontally oriented (elongated perpendicular to the long dimension of the housing 3) chambers that allow the coolant to flow horizontally across the heat pipes 8. Each baffle plate 10 has gaps 10 along its sides to allow the coolant to pass vertically to the next chamber. The gaps have alternating sides (i.e., left to right) to force the coolant to follow a "zig-zag" flow pattern along the length of the heat pipes 8. This allows the coolant to make multiple passes over the same heat pipe 8, thereby optimizing heat transfer by utilizing the entire length of the heat pipe 8 (i.e., having the dielectric coolant contact as many portions of the heat pipe 8 as possible along its entire length). Alternating sides of the gaps 10 can be achieved by simply stacking identical baffle plates 9 in alternating positions.

[0048] 6-9, only the heat sink 100 of the above-described embodiment is shown, shown in an isometric view in Fig. 6, a top view in Fig. 7, a side view in Fig. 8, and a front view in Fig. 9. All of the features shown in these figures have been described above and will not be described in detail again here.

[0049] 10, an exploded isometric view of the heat sink of FIG. 6 is shown, where the baffle plate 9 and gap 10 are shown from a different perspective. Additionally, the structure of the coolant inlet 6 is shown, which includes a housing opening 14 and a piping arrangement 6A removably coupled to the opening 14. Similarly, the structure of the coolant outlet 7 is shown, which includes a housing opening 15 and an upwardly facing portion 7A removably coupled to the opening 15.

[0050] It will be understood that the heat sink 100 and the electronic device 200 are disposed within a chassis (not shown). In the immersion cooling approach, according to the illustrated embodiment, the chassis is configured to collect the effluent coolant from the heat sink (which may flow through other components on the electronic device 200 or elsewhere within the chassis before or after collection). A pump typically located within the chassis drives the coolant through the chassis, but coolant convection may additionally or alternatively move the coolant. A heat exchanger may be provided, preferably within the chassis, to transfer heat from the dielectric coolant to a secondary coolant (e.g., water or water-based coolant). The heat exchanger may also be configured to maintain the dielectric (primary) coolant in a single (liquid) phase. Further details regarding such configurations are provided at least in WO 2019 / 048864, which is incorporated by reference in its entirety.

[0051] Referring back to the generalized meaning of the present disclosure above, further optional and / or advantageous features may be considered. For example, the heat transfer block may have a substantially flat surface and / or may be substantially flat. In some embodiments, the housing further comprises a lid. Optionally, the housing is made of a thermally insulating material.

[0052] In an embodiment, the heat pipes may extend substantially perpendicular to the plane of the heat transfer block. Additionally or alternatively, the heat pipes may extend substantially parallel to the sidewalls (of the housing).

[0053] Preferably, the length of at least one (more preferably, some, and optionally all) of the plurality of heat pipes is greater than a dimension of the heat transfer block (e.g., one or more of the width, length, diagonal size, radius, diameter of the heat transfer block).

[0054] The heat sink may further comprise a coolant inlet for receiving coolant from the exterior of the heat sink to the internal volume, and a coolant outlet for the coolant to leave the internal volume and be transported to the exterior of the heat sink. If the coolant inlet is in a part of the housing proximal to the heat transfer block, the coolant outlet is usually in a part of the housing distal to the heat transfer block, and conversely, if the coolant outlet is in a part of the housing proximal to the heat transfer block, the coolant inlet may be in a part of the housing distal to the heat transfer block. In the latter case, the coolant outlet may comprise a pipe configured to receive coolant from a part of the internal volume relatively close (proximal) to the heat transfer block and to convey or direct the received coolant to a (relatively) distal part of the heat transfer block (e.g., in a direction perpendicular to the plane of the heat transfer block, which may be upwards or vertical). The coolant can then exit the heat sink at such a distal location. Advantageously, the coolant inlet and / or the coolant outlet each comprise a connection port removably coupled to the housing (e.g., by a press-fit or threaded connection).

[0055] The multiple heat pipes may be arranged in a regular pattern, for example, the angle between the center of each heat pipe and one or more respective adjacent heat pipes may be 60 degrees.

[0056] In an embodiment, each of the plurality of heat pipes is disposed within a respective hole in the heat transfer block, and the sidewalls may be arranged such that heat is conducted along the sidewalls between the heat pipes perpendicular to the heat transfer block.

[0057] Beneficially, the heat sink further comprises one or more baffles arranged within the interior volume to direct the flow of coolant towards, away from, or across at least one of the plurality of heat pipes. Preferably, the one or more baffles comprise a plurality of substantially planar baffles distributed within the interior volume along a direction away from the heat transfer block. In this case, adjacent baffles may cover different portions of a cross-sectional area of ​​the interior volume. For example, adjacent baffles may alternate between different or opposing side walls. In either case, the baffles may be arranged to direct the flow of coolant throughout the plurality of heat pipes.

[0058] Further details may be considered regarding the cooling electronics system described above. For example, the system may further comprise a heat exchanger configured to receive coolant from the heat sink and transfer heat from the coolant to a heat dissipating fluid (e.g., a secondary coolant). Optionally, a piping arrangement may be arranged to transport the coolant between the heat exchanger and the heat sink. The heat exchanger may be located internal or external to the chassis. Additionally or alternatively, a pump may be provided to flow the coolant. The pump may be located to effect the flow of the coolant between the heat exchanger and the heat sink. The pump may be located internal or external to the chassis.

[0059] Preferably, the electronic device is a first electronic device and the cooling electronic system further comprises a second electronic device, which may be positioned such that coolant exiting the heat sink flows over or across the second electronic device (to cool the second electronic device).

[0060] Referring again to the generalized meaning of the present disclosure below, further details of specific embodiments and other configurations will be considered first.

[0061] 10-13, only the electronic device 200 of the above embodiment is shown, shown in isometric view in FIG. 11, plan view in FIG. 12 and side view in FIG. 13. Some of the features shown in these figures have been mentioned above, but they will now be considered in more detail. The electronic device 200 comprises a substrate (or circuit board) 19, a main processor chip 16, chiplets 17 and auxiliary components 20. This is purely an example of an electronic device that can be cooled by the heat sink 100 and is not considered limiting.

[0062] The main processor 16 is centrally located on a substrate or PCB 19, with four chiplets 17 mounted closely surrounding the main processor 16. Such close proximity is becoming more common as it can improve communication speeds between the chiplets 17 and the main processor 16. In this case, the main processor 16 and chiplets 17 are all coplanar and may be cooled by a heat sink 100 having a base plate 1 with a flat underside. In other examples, the chips 16, 17 may be at different heights. The base plate 1 of the heat sink 100 may then be shaped to fit the contours of the chips 16, 17.

[0063] The electronic device 200 is provided with a socket 18 onto which the heat sink 100 can be mounted. The actual socket 18 may have a slightly different appearance than that shown in the drawings. The spring arrangement 2 on the heat sink 100 may be mounted directly to the socket 18. As mentioned above, the auxiliary electrical components 20 on the substrate 19 may be cooled by dielectric overflow from the coolant outlet 7 of the heat sink 100.

[0064] In some embodiments, multiple heat sinks 100 may be provided within a single chassis, for example in a grid. As an example, between 6 and 12 heat sinks 100 may be provided in the same chassis.

[0065] Alternative designs of the heat sink are possible. For example, a dielectric coolant inlet may be provided at the base of the heat sink and a coolant outlet may overflow from the top of the heat sink. With reference to FIG. 14, an isometric view of a heat sink according to a second embodiment is shown along this line. Many of the details are the same as in the first embodiment described above and will not be repeated for the sake of brevity. The heat sink 100' has a dielectric coolant inlet 26 towards the base or bottom and a coolant outlet 27 towards the top (i.e. distal to the base). It has been found that the cooling performance of the heat sink is (perhaps only partially) better than that of the first embodiment. With reference to FIG. 15, a side view of the embodiment of FIG. 14 is shown and with reference to FIG. 16, an exploded isometric view of the heat sink of FIG. 14 is shown. It can be seen from these figures that other details of the heat sink 100' are essentially the same as those of the heat sink 100 of the first embodiment.

[0066] Referring now to FIG. 17, there is shown an exploded isometric view of a heat sink 100″ according to a third embodiment. From these views, it can be seen that many details of the heat sink 100″ are the same as those of the heat sink 100 of the first embodiment, so these will not be repeated for the sake of brevity. However, this embodiment uses vapor chambers 8A instead of heat pipes. The vapor chambers 8A operate similarly to heat pipes, but their profile is fin-shaped rather than pin-shaped. The use of fin-shaped vapor chambers 8A (i.e., flattened heat pipes) allows the heat to be spread from the center of the heat sink. This allows the heat transfer to be optimized throughout the base rather than using only heat pipes as described above.

[0067] As noted above, the design of this embodiment is shown similar to the first embodiment with a dielectric coolant inlet at the top of the heat sink and a coolant outlet at a lower elevation, but with an upwardly facing portion configured to allow the dielectric coolant to rise before overflowing. However, it will be appreciated that the configuration of this design can be easily adjusted to fit the second embodiment with respect to the dielectric coolant inlet and coolant outlet.

[0068] Referring to Figure 18, a side view of the embodiment of Figure 17 is shown, and referring to Figure 19, a top cross-sectional view of the embodiment of Figure 17 is shown along section DD shown in Figure 18. The different internal structure of this heat sink design can be seen, however, its operation is essentially the same as that described above with reference to the first embodiment.

[0069] In another design, the base plate may include a vapor chamber. Additionally, heat pipes (i.e., pin-shaped vapor chambers) may be made from the same vapor chamber as the base. The role of the heat sink may be thought of as spreading the thermal energy from a small concentrated heat source over a much larger area, where the heat then flows by convection to the surrounding fluid. As explained with reference to the previous design, the heat is first transported a short distance from the heat source by conduction in the solid metal base, and then efficiently transported by several heat pipes. This can provide a large wetted area for convection to the surrounding fluid. It is envisioned that the thermal performance of the heat sink can be improved by minimizing the internal thermal resistance of the heat sink. Adaptation of the base plate can achieve this additional objective, as explained below.

[0070] The thermal performance of high power density devices can be improved compared to the previous embodiments by better spreading the heat laterally (i.e., in the plane of the heat source or base plate). This may also allow more heat pipes (and / or vapor chambers) to be engaged in the heat transfer process than in the previously described designs. The use of a solid metal base to achieve this lateral heat spreading would result in significant thermal resistance, which could adversely affect overall performance.

[0071] Referring now to FIG. 20, an exploded isometric view of a heat sink 100"' according to such a fourth embodiment is shown. See also FIG. 21, which shows a front view of this embodiment, and FIG. 22, which shows a side cross-sectional view of the embodiment along section FF shown in FIG. 21. As shown, an integrated base plate and heat pipe structure 21 is provided with at least one vapor chamber (preferably forming a single vapor chamber structure). The integrated structure 21 thus helps to spread heat laterally (in the plane of the heat source) using the same two-phase heat transfer process as previously described within a heat pipe. By integrating the base plate and heat pipes into a single structure 21, a continuous closed internal cavity is provided that performs the functions of both the vapor chamber and the heat pipe. The thermal performance of this design is therefore improved compared to heat flow through a solid metal interface between the base plate and the heat pipe, or between the vapor chamber and the heat pipe.

[0072] It can also be seen that the external profile of heat sink 100''' is approximately the same shape and size as the "heat sink for heat pipe" design. The surface area exposed to the surrounding fluid is the same, as is the pressure drop imparted to that surrounding fluid.

[0073] Like the third embodiment, the design of the fourth embodiment is shown with a dielectric coolant inlet at the top of the heat sink and a coolant outlet at a lower elevation, like the first embodiment, but with an upwardly facing portion configured to raise the dielectric coolant before it overflows. However, it will be appreciated that the configuration of this design can be easily adjusted to fit the second embodiment with respect to the dielectric coolant inlet and coolant outlet.

[0074] Returning to the general meaning of the present disclosure, it will be understood that heat pipes and / or vapor chambers can be used, rather than just heat pipes, in other words, where the term heat pipe is used above, it may be replaced by a vapor chamber.

[0075] Although specific embodiments have been described, those skilled in the art will appreciate that various modifications and variations are possible. As mentioned above, the illustrated embodiment is a heat sink for immersion cooling where the outflowing coolant is used to cool other components in the same chassis, but alternative closed loop cold plate configurations can be used. Although a dielectric coolant is preferred for immersion cooling, the closed loop cold plate arrangement may use a different coolant, in particular water or water-based coolants. The coolant used is preferably single phase (in other words, the heat sink is designed so that the coolant remains in liquid phase), but a two-phase coolant can be used instead (the heat sink is designed so that the coolant is boiled). In the case of the cold plate, the coolant flow is advantageously balanced so that the flow penetrates the entire length of the heat pipes. A heat exchanger and / or pump for the cold plate may be provided in the outer chassis (where the heat sink and electronic devices are located) or external to the chassis. The heat exchanger can transfer heat from the coolant flowing through the cold plate to another coolant fluid (which may be liquid or gas).

[0076] In a closed cold plate (or other embodiment), the location of the coolant inlet and coolant outlet may vary. For example, in one implementation, the coolant inlet may pass through the lid generally opposite the hottest portion of the device being cooled (e.g., the center of the top surface of the lid). The coolant outlet may pass through the lid to the side of the top surface of the lid. The coolant inlet may be collinear with the heat pipe in certain implementations, allowing maximum contact between the coolant fluid and the heat pipe surface area along the height dimension without the need for heat pipe surface extension fins.

[0077] In general, it is not necessary that the coolant inlet is located at the top of the housing and the coolant outlet is located at the bottom of the housing. In fact, the coolant inlet and coolant outlet of the embodiment shown in the drawings (and described above) can be reversed. In this case, the upwardly facing portion 7A may be omitted or replaced by a pipe. By using removable couplings for the coolant inlet and coolant outlet, these connections can be easily modified. Also, for heat sinks that are not cold plates, the coolant outlet does not need to have an associated pipe. For example, the coolant outlet may simply comprise a hole or opening in the housing or the top plate (lid). The coolant may simply overflow from the housing. In some cases, no top plate may be provided and the coolant outlet may comprise an opening formed by the top of the housing. Multiple coolant outlets can be provided, which can be arranged, for example, symmetrically to promote equal flow distribution within the internal volume or according to the thermal profile of the electronic component below, resulting in a higher flow rate over certain parts of the heat transfer surface than others. Multiple coolant inlets may be used, but this becomes more complicated.

[0078] Different configurations and / or arrangements of heat pipes are possible. For example, the shape and / or size of the heat pipes may be different than those shown. Also, heat pipes of different shapes and / or sizes may be provided within the same heat sink. For example, an array of heat pipes with two different diameters may minimize turbulence and provide a larger heat pipe surface area than a single array. The cross-sectional shape of the heat pipes (perpendicular to the long dimension) may be circular, rectangular, hexagonal, or other. In some embodiments, two or more different types of heat pipes (each type having a particular shape and size) may be used. The pitch spacing and / or angle of the heat pipes may be varied to optimize thermal performance, particularly depending on the size and shape of the heat pipes used.

[0079] In another option, the housing in which the heat pipes and coolant fluid are contained may form a unique manifold that directs flow from an inlet to one or more outlet ports. The manifold may optionally combine the flow from the outlet ports into a single outlet.

[0080] The heat pipes are preferably soldered into the heat transfer block, but may be metallurgically joined in other ways, allowing the distance between the heat source and the heat pipes to be minimized while still allowing heat to be conducted along the wall between the heat pipes perpendicular to the heat source, bypassing the less efficient crimped ends of the heat pipes.

[0081] The housing is preferably formed from plastic, although other materials may be used, particularly materials that are insulating. Additionally or alternatively, insulation around the housing may be used to minimize heat transfer to the surrounding environment.

[0082] The use of baffles within the interior volume of the heat sink may be advantageous, and other baffle patterns may be provided (e.g., to direct flow toward certain heat pipes if they are operating relatively hard due to the thermal profile of the electronic device being cooled). Optionally, no baffles may be used.

[0083] As detailed above, other versions include a dielectric coolant inlet at the base with the coolant outlet overflowing out the top. This can also be converted into a cold plate with a closed water-based coolant loop if hoses are secured to the inlet and outlet.

[0084] An embodiment is shown that uses only heat pipes and only vapor chambers. However, it will be understood that heat pipes and vapor chambers can be used in any combination. For example, there may be at least one heat pipe and at least one vapor chamber extending from a heat transfer block within the interior volume of the heat sink.

[0085] In an embodiment, the heat transfer block comprises a vapor chamber. Preferably, the vapor chamber of the heat transfer block is integral with the plurality of heat pipes and / or vapor chambers extending from the heat transfer block. For example, the internal volume of the vapor chamber of the heat transfer block may be continuous with the internal volume of the plurality of heat pipes and / or vapor chambers extending from the heat transfer block.

[0086] Returning to the general sense of the disclosure above, further optional features may be considered: for example, the lid may be arranged to seal the internal volume such that the heat sink is a cold plate.

[0087] In some implementations, the coolant inlet is collinear with the plurality of heat pipes.Optionally, the coolant inlet is in the center of the lid.

[0088] The housing may be configured to transport coolant from a coolant inlet to bases of the plurality of heat pipes proximate the heat transfer block. The plurality of heat pipes may then be arranged to flow coolant from the bases of the plurality of heat pipes to a coolant outlet. The heat sink may further comprise a manifold arranged to channel coolant from the coolant inlet to a plurality of locations at the bases of the plurality of heat pipes. For example, the multiple locations may be symmetrically arranged (e.g., in a plane parallel to the heat transfer block) across the bases of the plurality of heat pipes. The housing may be further configured to define a manifold.

[0089] In embodiments, the plurality of heat pipes have different cross-sectional (long dimension) sizes and / or shapes. For example, the plurality of heat pipes can include a first set of heat pipes, each having a first cross-sectional area, and a second set of heat pipes, each having a second cross-sectional area smaller than the first cross-sectional area, each disposed between the heat pipes of the first set of heat pipes. In certain implementations, the plurality of heat pipes have a cross-sectional shape that is one of a circle, a polygon, a rectangle, and a hexagon.

[0090] Optionally, the heat sink further comprises an insulator disposed around the outside of the housing.

[0091] In certain embodiments, an exterior surface of an electronic device has a thermal profile during use. The coolant inlet of the heat sink may then be aligned with the hottest portion of the thermal profile. Additionally or alternatively, the center of the heat transfer block may be aligned with (or adjacent to) the hottest portion of the thermal profile.

[0092] 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. 1. A heat sink for cooling a heat generating device, comprising: a housing comprising a heat transfer block for receiving heat from the heat generating device and a sidewall extending from the heat transfer block, the heat transfer block and the sidewall together defining an interior volume for receiving a coolant from an exterior of the heat sink; a plurality of heat pipes and / or vapor chambers each extending from the heat transfer block within the interior volume.

2. The heat sink of claim 1 , wherein the plurality of heat pipes and / or vapor chambers extend substantially perpendicular to a plane of the heat transfer block and / or substantially parallel to the sidewalls.

3. 10. The heat sink of any preceding claim, wherein a length of at least one of the plurality of heat pipes and / or vapor chambers is greater than a dimension of the heat transfer block.

4. 10. A heat sink as claimed in any preceding claim, wherein the housing further comprises a lid arranged to seal the internal volume such that the heat sink is a cold plate.

5. 10. The heat sink of any preceding claim, further comprising a coolant inlet for receiving coolant from outside the heat sink into the internal volume, and a coolant outlet for transporting coolant out of the internal volume to the exterior of the heat sink.

6. 6. The heat sink of claim 5, wherein the coolant outlet comprises a pipe configured to receive coolant from a portion of the interior volume relatively close to the heat transfer block and convey the received coolant in a direction perpendicular to a plane of the heat transfer block to a portion relatively distal to the heat transfer block.

7. The heat sink of claim 5 or 6, wherein the coolant inlet and / or coolant outlet each comprise a connection port removably coupled to the housing.

8. 10. The heat sink of any preceding claim, wherein the sidewall is formed from a plurality of modules, each module defining a portion of the sidewall such that the modules are stacked on the heat transfer block to define the interior volume.

9. 10. The heat sink of any preceding claim, wherein the plurality of heat pipes are arranged in a regular pattern, the angle between the center of each heat pipe and one or more respective adjacent heat pipes being 60 degrees.

10. 10. A heat sink as claimed in any preceding claim, wherein the plurality of heat pipes and / or vapor chambers have different cross-sectional sizes and / or shapes.

11. The plurality of heat pipes and / or vapor chambers include: a first set of heat pipes or vapor chambers each having a first cross-sectional area; 11. The heat sink of claim 10, comprising: a second set of heat pipes or vapor chambers each having a second cross-sectional area smaller than the first cross-sectional area and each disposed between the heat pipes or vapor chambers of the first set of heat pipes or vapor chambers.

12. 12. The heat sink of claim 10 or 11, wherein the plurality of heat pipes and / or vapor chambers have a cross-sectional shape that is one of circular, polygonal, rectangular, fin-shaped, and hexagonal.

13. 10. The heat sink of any preceding claim, wherein the plurality of heat pipes and / or vapor chambers are soldered or metallurgically bonded into the heat transfer block.

14. 10. The heat sink of any preceding claim, wherein each of the plurality of heat pipes and / or vapor chambers is disposed within a respective hole in the heat transfer block.

15. The heat sink of any preceding claim, wherein the heat transfer block comprises a vapor chamber integral with the plurality of heat pipes and / or vapor chambers.

16. further comprising one or more baffles disposed within the interior volume to direct a flow of coolant toward, away from, or across at least one heat pipe of the plurality of heat pipes and / or vapor chambers. A heat sink according to any preceding claim.

17. 17. The heat sink of claim 16, wherein the one or more baffles comprise a plurality of substantially planar baffles distributed within the interior volume along a direction away from the heat transfer block, adjacent baffles covering different portions of a cross-sectional area of ​​the interior volume, thereby channeling the coolant across a plurality of heat pipes and / or vapor chambers.

18. the housing is made of a thermally insulating material; the heat sink further comprises insulation disposed around an exterior of the housing; A heat sink according to any preceding claim.

19. 10. A heat sink as claimed in any preceding claim, wherein the coolant is a liquid.

20. 1. A cooling electronics system comprising: an electronic device that generates heat during use, the heat being dissipated from the electronic device through an exterior surface of the electronic device; 13. A cooled electronic system comprising: a heat sink according to any preceding claim having a heat transfer block attached to the exterior surface of the electronic device.

21. a heat exchanger configured to receive a coolant from the heat sink and to transfer heat from the coolant to a heat dissipation fluid; a piping arrangement configured to transport a coolant between the heat exchanger and the heat sink.

21. The cooled electronics system of claim 20.

22. a pump disposed to effect a flow of the coolant between the heat exchanger and the heat sink.

22. The cooled electronics system of claim 21.

23. 23. The cooled electronics system of claim 20, wherein the electronic device is a first electronic device and the cooled electronics system further comprises a second electronic device, the second electronic device being positioned such that coolant flowing from the heat sink flows over the second electronic device.

24. The cooled electronics system of any one of claims 20 to 23, further comprising a chassis, the electronic device and heat sink being disposed within the chassis.

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