Heat sink with phase change plug and dissipative coolant

Abstract

An apparatus and method for quenching thermal runaway in an electronic component are provided. The apparatus includes a heat sink secured to the electronic component, a reservoir containing a coolant, and one or more phase change material (PCM) plugs that block the coolant contained in the reservoir, where the PCM plugs melt in response to the temperature of the electronic component approaching a phase change temperature (PCT) of the PCM plugs, thereby dispersing the coolant over the electronic component. The method includes melting the one or more phase change material (PCM) plugs in response to the electronic component reaching a temperature indicative of a thermal runaway event occurring within the electronic component, where the PCM plugs prevent the coolant from escaping from the reservoir. In response to the melting of the PCM plugs, the coolant is released from the reservoir onto the electronic component to quench the thermal runaway event (FIG. 1A).

Description

[Technical Field]

[0001] Background of the Invention The present invention relates generally to the field of heat sinks for electronic components, and more particularly to quenching thermal runaway events that may occur within electronic components.

[0002] Heat sinks provide the necessary cooling for electronic components by transferring or dissipating heat from the component to the heat sink. To accomplish this, heat sinks are typically metal structures that draw heat away from hot electronic components. Most heat sinks have fins or other structural features that dissipate the transferred heat into the surrounding air faster than the electronic component can achieve on its own. However, various design or manufacturing errors can cause electronic components to reach dangerous temperatures that are too high for the heat sink to effectively cool the component. This scenario is often referred to as a thermal runaway event, as heat accumulates and continues to increase until the component fails. Heat buildup within the component can cause the component to fail and potentially damage other nearby components. Summary of the Invention

[0003]

[0006] Embodiments of the present invention provide an apparatus for quenching thermal runaway in an electronic component, the apparatus including: a heat sink secured to the electronic component; a reservoir within the heat sink, the reservoir containing a coolant and having a drain; and a phase change material (PCM) plug proximate to the electronic component, the PCM plug secured to the drain and preventing the release of the coolant contained in the reservoir. In response to the temperature of the electronic component approaching a phase change temperature (PCT) of the PCM plug, the PCM plug melts, thereby allowing the coolant to be released, pass through the drain, and be dispersed over the electronic component.

[0004] Embodiments of the present invention are directed to a method for quenching thermal runaway in an electronic component, the method including: securing a heat sink to an electronic component, the heat sink including a reservoir for containing a coolant, a drain for releasing the coolant from the reservoir, and a phase change material (PCM) plug for preventing the drain from releasing the coolant; melting the phase change material (PCM) plug in response to the electronic component reaching a temperature indicative of a thermal runaway event occurring within the electronic component; and releasing and dispersing the coolant over the electronic component in response to the PCM plug melting, thereby quenching the thermal runaway event. [Brief explanation of the drawings]

[0005] [Figure 1] 1A and 1B show a heat sink with a dissipative coolant that prevents thermal runaway, according to one embodiment of the present invention.

[0006] [Figure 2] 2A and 2B show a heat sink with dissipative coolant and piping according to one embodiment of the present invention.

[0007] [Figure 3] 3A and 3B show a heat sink with a dissipative coolant and a containment wall according to one embodiment of the present invention.

[0008] [Figure 4A] 1 illustrates a heat sink with a dissipative coolant containing microcapsules, according to an embodiment of the present invention. [Figure 4B] 1 illustrates a heat sink with a dissipative coolant containing microcapsules, according to an embodiment of the present invention.

[0009] [Figure 5]Exemplary processes utilizing a heat sink with a dissipative coolant, a heat sink with a dissipative coolant and piping, a heat sink with a dissipative coolant and containment wall, and a heat sink with a dissipative coolant containing microcapsules are shown. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0004] Embodiments of the present invention are directed to a heat sink with a reservoir containing a kill coolant that will prevent a thermal runaway event from destroying or damaging other components when a component fails. Prior heat sink solutions have not offered any methodology or structure for containing and distributing the kill coolant necessary to prevent a thermal runaway event. Additionally, prior solutions for utilizing kill coolant to prevent damage do so by utilizing external devices and sensors, typically flooding the entire device to stop further damage.

[0011] Embodiments of the present invention recognize that incorporating a dissipative coolant within a heat sink provides various improvements over conventional solutions. In various scenarios, as with most liquid cooling solutions, adding coolant within the heat sink's reservoir results in additional heat absorption. Furthermore, the coolant is confined to components that may be susceptible to a thermal runaway event. Thus, in the event of a runaway, the coolant can be quickly and locally dispersed over the failing component, whereas in conventional solutions, the enclosure is flooded and there is no guarantee that the dissipative coolant will be quickly dispersed over the problem component.

[0012] Additionally, embodiments of the present invention provide a phase change material (PCM) plug that retains the expiring coolant in a reservoir until a runaway event occurs. Once the component reaches a temperature threshold, the PCM plug melts, dispersing the expiring coolant directly onto the component. As such, embodiments of the present invention do not require a sensor or other active device to distribute the coolant, thereby increasing the reliability of embodiments of the present invention in scenarios where damage to an active sensor in a conventional solution could cause it to fail due to loss of power or other damage.

[0013] Various aspects of the present disclosure are described using text, flowcharts, computer system block diagrams, and / or machine logic block diagrams included in computer program product (CPP) embodiments. For any flowchart, operations may be performed in an order different from that shown in a given flowchart, depending on the technology involved. For example, two operations shown in successive flowchart blocks may be performed in the reverse order, as a single integrated step, simultaneously, or at least partially overlapping in time, again depending on the technology involved.

[0014] The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in the flowcharts or block diagrams may represent a module, segment, or portion of instructions, including one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the blocks may occur in an order different from that noted in the figures. For example, two blocks shown in succession may actually be performed as a single step, executed simultaneously, executed substantially simultaneously, partially or fully overlapping in time, or the blocks may even be executed in the reverse order, depending on the functionality involved. It will also be understood that each block of the block diagrams and / or flowchart diagrams, and combinations of blocks in the block diagrams and / or flowchart diagrams, may be implemented by a special-purpose hardware-based system that performs the specified functions or acts or executes a combination of special-purpose hardware and computer instructions.

[0015] 1A and 1B illustrate a heat sink, generally designated 100, with a dissipating coolant that prevents thermal runaway. In various embodiments, the heat sink 130 includes a reservoir 110 containing a coolant 120. In FIG. 1A, the phase change material (PCM) plugs 114 are intact (i.e., intact PCM plugs 114a). Each plug 114 is located at the distal end of a drain 116, such that when the plug 114 is intact (i.e., intact PCM plug 114a), the plug 114 prevents the coolant 120 from escaping the reservoir 110. When the temperature of the PCM plug 114 reaches a threshold temperature (i.e., a temperature indicative of a thermal runaway event), the PCM plug 114 melts, becoming a molten PCM plug 114b, as shown in FIG. 1B. Once the PCM plug 114 melts, the coolant 120 gravity flows down the drain 116 to provide coolant to the electronic components 140, thereby extinguishing the components and preventing further damage from a thermal runaway event.

[0016] In various embodiments, component 140 is any electronic component that generates heat and may experience a thermal runaway event if not properly cooled. For example, component 140 may be a central processing unit (CPU), a graphics processing unit (GPU), or an application-specific integrated circuit (ASIC), such as a neural network processor. Those skilled in the art will appreciate that heat sink 100 with dissipative coolant may be affixed to any electronic component in which a thermal runaway event may occur, including, but not limited to, system memory (i.e., random access memory), solid-state storage devices (SSDs), systems-on-a-chip (SoCs), and programmable circuits such as fully programmable gate arrays (FPGAs). In many scenarios, heat sink 130 is affixed to component 140 using thermal paste 142. Thermal paste 142 bonds the component to the heat sink, allowing for effective heat transfer between heat sink 130 and component 140. Those skilled in the art will appreciate that thermal paste 142 may be any thermally conductive compound that facilitates heat transfer between heat sink 130 and component 140, such as any polymer containing thermally conductive materials that bond and facilitate such heat transfer. In some embodiments, thermal paste 142 may comprise a pre-cured silicone gel that includes a highly conformal silicone matrix filled with ceramic fillers.

[0017] In various embodiments and scenarios, component 140 is affixed to or coupled to a printed-circuit board (PCB) 144. PCB 144 serves as a structure for connecting component 140 to other devices and components with the device (not shown). If component 140 fails and causes a thermal runaway, component 140 may damage nearby components on PCB 144. By quickly extinguishing a thermal runaway event, embodiments of the present invention can prevent further damage to other components. Additionally, sparing other components on PCB 144 improves failure analysis by facilitating diagnosis and identification of the failing component, since damage does not propagate to other components connected to PCB 144.

[0018] In various embodiments, the heat sink 130 is any device or structure that provides heat exchange from the component 140 to another medium, such as air or a liquid. The heat sink 130 is shown as an air-cooled heat exchanger, which typically has fins 132 extending from the heat sink to better dissipate heat into the surrounding air. In some embodiments, the heat sink 130 includes a cooling plate (not shown) for liquid cooling of the component 140. In further embodiments, the heat sink 130 also includes heat pipes (not shown) that transfer heat from the component 140 to the heat sink 130. Those skilled in the art will appreciate that embodiments of the present invention may utilize a variety of heat sinks without departing from the present invention, provided that the reservoir 110 is connected to the component 140 so that the coolant 120 can be dispersed over the component 140 in the event of a thermal runaway event.

[0019] In various embodiments, the heat sink 130 includes a cavity for storing the coolant 120. Additionally, the drain 116 is surrounded by the heat sink 130, such that the drain 116 is connected to the reservoir 110 and allows the coolant 120 to flow over the component 140 in the event of a thermal runaway. The coolant 120 may be any of a variety of coolants or quenching media, such as, but not limited to, a halocarbon (e.g., heptafluoropropane or fluoroketone), glycol, or an oxygen-reducing media such as pressurized carbon dioxide gas. Those skilled in the art will appreciate that any type of coolant or quenching media may be used within the reservoir 110 as the coolant 120. In various scenarios, the coolant 120 should be able to quickly quench a thermal runaway event in the component 140 or otherwise prevent it from affecting other components on the PCB 144.

[0020] In various embodiments, the drain 116 leads from the reservoir 110 for depositing the coolant 120 onto the component 140 have at least one phase change material (PCM) plug 114 at the distal end of each drain 116 from the reservoir 110. As discussed herein, the PCM plug 114 will melt when brought to a phase change temperature by heat generated by the component 140, thereby unblocking the drain 116, allowing the coolant 120 in the reservoir 110 to be released and dispersed by gravity onto the component 140 once the PCM plug 114 melts.

[0021] As shown in FIGS. 1A-4B , the drain 116 extends from the reservoir 110 such that the distal end of the drain 116 contacts or is in close proximity to the component 140, facilitating inductive heating of the PCM plug 114. Additionally, the reservoir 110 is surrounded by or otherwise a part of the heat sink 130, such that the coolant 120 can provide some additional heat absorption and efficiency to the heat sink 130. Those skilled in the art will appreciate that the location and arrangement of the reservoir 110 and drain 116 can be varied from the configuration and design shown in FIGS. 1A-4B . For example, the drain 116 need not be a channel extending from the reservoir 110, but rather a hole or any other exit point for releasing the coolant from the reservoir 110 when the PCM plug 114 melts. Further modifications to the drain 116, such as a bypass channel 150, are discussed herein. Those skilled in the art will appreciate that various modifications can be made to the placement, size, and arrangement of reservoir 110 and drain 116 based on cooling, budget, and other needs without departing from the invention.

[0022] A phase change material is a material that can change its state of matter when exposed to certain environmental factors, such as temperature. For example, when a PCM material is at a low temperature, the material is solid; when the PCM material is exposed to a high temperature, it transitions to a liquid. Ice or frozen water is a classic example of this phenomenon. However, modern developments have produced a wide range of such materials with different phase change points to accommodate different applications. While water turns into ice when exposed to a temperature of approximately 32°F (0°C), PCMs used in electronic components require a much higher phase change temperature (PCT).

[0023] In various embodiments, depending on the design and construction of the component 140, the temperature at which thermal runaway and failure of the component 140 will occur may vary. In semiconductors, the resistance of silicon typically increases until a critical point of approximately 160° C. is reached, at which point the semiconductor's resistance significantly decreases, generating excessive current and therefore heat, typically resulting in thermal runaway. In this scenario, the PCM plug 114 would be selected to have a PCT of approximately 160° C., where the PCM plug 114 is solid and intact below the PCT (i.e., intact PCM plug 114a) and melts above the PCT (i.e., molten PCM plug 114b). Exemplary PCM materials that operate at PCTs within this range include hydrocarbons and other organic PCMs, or salt hydrates and other inorganic PCMs.

[0024] 1B, the PCM plug 114 melts (i.e., 114b) due to the component 140 reaching or exceeding its PCT. Therefore, the intact PCM plug 114a no longer provides a quiescent hold for the coolant 120. Gravity draws the coolant 120 from the reservoir 110 through the directional channels 116 and deposits it on the component 140. While the component 140 may be damaged due to thermal runaway, eliminating the thermal runaway occurring in the component 140 may save surrounding components on the PCB 144. The overheating is stopped by spraying the coolant 120 directly onto the component 140. While conventional solutions may deposit coolant during component thermal runaway, these solutions do so over the entire enclosure or device, rather than depositing the coolant locally as discussed herein. By storing the coolant 120 within the heat sink, not only is the efficiency of the heat sink 130 increased, but the coolant 120 also serves the dual purpose of quenching thermal runaway and destroying specific components. By injecting a localized amount of coolant into the failing component, failure analysis is improved because only the problem component is covered in coolant and destroyed, while other non-faulty components remain intact for failure analysis and possible re-use.

[0025] 2A and 2B illustrate a heat sink with dissipative coolant and piping, generally designated 200, according to one embodiment of the present invention. In FIG. 2A, the heat sink 130 includes a reservoir 110 containing coolant 120. An intact PCM plug 114 blocks the directing channel 116 from the reservoir until it heats up to the PCT of the material used in the PCM plug 114 (e.g., a component 140 is nearing its PCT threshold and is inducing heat onto the intact PCM plug 114a to reach its PCT, indicating that thermal runaway may be occurring in the component 140).

[0026] In some embodiments, the heat sink 130 also includes bypass channels 150, which divert the coolant so that it is sprayed directly onto the component 140. Because inductive heating of the PCM plug 114 through dissipation by the component 140 is required to trigger a phase change in the PCM plug 114, the PCM plug 114 should be positioned in close proximity to the component 140. If the distance is too great, the PCM plug 114 may not melt if the component 140 experiences thermal runaway. Furthermore, the thermal paste 142 and other materials or structures may block the delivery of the coolant 120 onto the component 140 and potentially impede the flow of the coolant 120. Thus, in FIG. 2A , the intact PCM plug 114 is positioned in close proximity to the component 140, with only the thermal paste 142 and a small portion of the heat sink 130 between the two.

[0027] 2B, the temperature of the component 140 has reached approximately the PCT of the PCM plug 114, causing the PCM plug 114 to become a molten PCM plug 114b and unblock the directing channel 116 from the reservoir 110. If the PCM plug 114 did not block the directing channel 116, the coolant 120 would flow into the bypass channel 160, which would then direct the coolant directly onto the component 140 while bypassing any intervening materials or structures, such as the thermal paste 142.

[0028] 3A and 3B illustrate a heat sink with a dissipative coolant and containment wall, generally designated 300, according to one embodiment of the present invention. In FIG. 3A, the heat sink 130 includes a reservoir 110 containing coolant 120. An intact PCM plug 114 blocks directional channels 116 from the reservoir until heated to the PCT of the material used in the PCM plug 114. In some embodiments, the heat sink 130 includes a containment wall 160 that surrounds the bottom periphery of the heat sink 130. Although discussed separately, in various embodiments, the containment wall 160 is a continuous portion of the heat sink 130. Additionally, the bottom of the containment wall 160 is sealed to the PCB 144 using an encapsulant 162 to better contain the coolant 120 upon application. In some embodiments, the containment wall 160 need not be an overhanging portion of or a portion of the heat sink 130. For example, a carbon composite material could be secured to the heat sink 130 and PCB 144 to form the containment wall 160 (not shown).

[0029] 3B , the temperature of the component 140 has reached approximately the PCT of the PCM plug 114, causing the PCM plug 114 to become a molten PCM plug 114b, unblocking the directional channel 116 from the reservoir 110. The application of a containment wall 160 and encapsulant 162 around the bottom perimeter of the heat sink 130 safely keeps the coolant 120 within the localized area of ​​the heat sink 130, thereby limiting the spread of the coolant 120 to neighboring components. Similar to conventional solutions that indiscriminately flood components on the PCB 144 during thermal runaway, such an embodiment in which the coolant 120 is further contained by the containment wall 160 aids in failure analysis and repair of the PCB 144 by limiting any damage and cleanup to only the component with the heat sink 130.

[0030] 4A and 4B illustrate a heat sink with a dissipating coolant containing microcapsules, generally designated 400, according to one embodiment of the present invention. In FIG. 4A, the heat sink 130 includes a reservoir 110 containing the coolant 120. An intact PCM plug 114 blocks the directional channel 116 from the reservoir until heated to the PCT of the material used in the PCM plug 114. In some embodiments, the coolant 120 includes microcapsules 122a. The microcapsules 122a include a shielding layer that forms a compartment storing a reactive coolant that, when mixed with the coolant 120, provides enhanced cooling, thereby dissipating a thermal runaway event more quickly than the coolant 120 could achieve alone. The shielding layer may be any polymeric material, such as, but not limited to, poly(4-aminocyclohexylene acetic acid); poly(1,4-cyclohexylene adipamide); poly(acrylonitrile); syndiotactic polymer; or polysulfone. As used herein, the term "microcapsules" is used to refer to capsules having diameters ranging from about 10 microns to 1000 microns, although it will be understood that the following disclosure may apply to capsules of smaller sizes (also called "nanocapsules").

[0031] The material of the shield layer should be selected to have a melting point equal to or higher than the expected temperature of a thermal runaway event (i.e., approximately 160°C). For example, the melting temperature of poly(acrylonitrile) is approximately 200°C. In various embodiments, the coolant 120 includes, is mixed with, or otherwise contains a first reactant, and the microcapsules 122a contain a second reactant. When the shield ruptures (as shown in FIG. 4B as ruptured microcapsule 122b), the first and second reactants mix, causing an endothermic reaction that further quenches the thermal runaway event occurring in the component 140. For example, the first reactant may be water, where the coolant 120 is composed entirely of water and the microcapsules 122a contain ammonium nitrate as the second reactant. When the component 140 reaches the temperature of a thermal runaway event, thereby breaching the shielding layer, the water and ammonium nitrate mix, creating an endothermic reaction that further quenches the thermal runaway event. Other reactant pairs may include, but are not limited to, barium hydroxide / ammonium thiocyanate or thionyl chloride / cobalt sulfate heptahydrate. Those skilled in the art will recognize that any mixture of reactants that, when mixed, results in an endothermic reaction may be used without departing from the invention.

[0032] 5 illustrates an exemplary process, generally designated 500, utilizing heat sink 100 with dissipative coolant, heat sink 200 with dissipative coolant and piping, heat sink 300 with dissipative coolant and containment wall, and heat sink 400 with dissipative coolant containing microcapsules. As discussed herein, heat sink 130 is affixed to electronic component 140. In some scenarios, electronic component 140 may overheat and experience a thermal runaway event, which typically occurs in integrated circuit packages at approximately 160° C. When this occurs, coolant 120 disperses over electronic component 140 to dissipate the thermal runaway event and prevent it from damaging other components.

[0033] In step 502, a heat sink 130 with a reservoir 110 for storing coolant 120 is secured to an electronic component 140. At normal operating temperatures, the heat sink 130 operates in a typical manner, providing cooling to the electronic component 140 (step 504). Because the heat sink 130 is secured to the electronic component 140, heat generated by the electronic component 140 is induced across the thermal interface between the electronic component 140 and the heat sink 130. Therefore, when the PCM plug 114 is placed in close proximity to the electronic component 140, the PCM plug 114 will also be heated by the electronic component 140.

[0034] At evaluation step 506, if the electronic component 140 reaches a high enough temperature, sufficient heat is induced to melt the intact PCM plug 114a, forming a molten PCM plug 114b. If the PCM plug 114a is not heated to its melting point (NO branch of evaluation step 506), the PCM plug 114a remains intact and the coolant 120 is maintained within the reservoir 110. However, once the intact PCM plug 114a is exposed to a temperature that melts the plug (YES branch of evaluation step 506), the coolant 120 is no longer blocked by the PCM plug 114. At step 508, once the PCM plug 114 melts, the reservoir 110 is no longer blocked by the PCM plug 114, allowing the coolant 120 to distribute over the electronic component 140. Once the coolant 120 has dispersed, the thermal runaway event will cease (step 510), thereby preventing any further damage caused by the event.

Claims

1. 1. A device for localized distribution of coolant to an electronic component to be protected in the event of thermal runaway, said device comprising: a heat sink fixed to the electronic component; a reservoir within the heat sink, the reservoir containing a coolant and having a drain; and a phase change material (PCM) plug adjacent to the electronic component, the PCM plug secured to the drain and preventing the release of the coolant contained within the reservoir, wherein: In response to the temperature of the electronic component approaching a phase change temperature (PCT) of the PCM plug, the PCM plug melts, thereby allowing the coolant to be released and dispersed through the drain onto the electronic component. An apparatus comprising:

2. 10. The apparatus of claim 1, wherein the PCT of the PCM plug is approximately equal to a temperature at which a thermal runaway event would be triggered in the electronic component.

3. The apparatus further comprises: a peripheral wall, wherein the peripheral wall surrounds the electronic component; 10. An apparatus according to any of the preceding claims, comprising:

4. The apparatus of claim 3 , wherein the peripheral wall contains the coolant in an area surrounding the electronic component.

5. The apparatus further comprises: a bypass channel, wherein the bypass channel directs coolant directly to a surface of the electronic component; 10. An apparatus according to any of the preceding claims, comprising:

6. The apparatus further comprises: a plurality of microcapsules mixed with the coolant, wherein the microcapsules rupture when in proximity to the PCT of the PCM plug; 10. An apparatus according to any of the preceding claims, comprising:

7. 1. A method for quenching a thermal runaway event in an electronic component, the method comprising: Securing a heat sink to an electronic component, the heat sink comprising: a reservoir containing a coolant; a drain for releasing the coolant from the reservoir; and A phase change material (PCM) plug that prevents the drain from releasing the coolant Includes; melting the phase change material (PCM) plug in response to the electronic component reaching a temperature indicative of a thermal runaway event occurring within the electronic component; and in response to the PCM plug melting, releasing and dispersing the coolant over the electronic component, thereby quenching the thermal runaway event. A method comprising:

8. 8. The method of claim 7, wherein a phase change temperature (PCT) of the PCM plug is approximately the temperature that indicates the thermal runaway event is occurring within the electronic component.

9. 9. The method according to any one of claims 7 to 8, wherein the reservoir is surrounded by a heat sink fixed to the electronic component.

10. providing a peripheral wall surrounding the electronic component; 10. The method of any one of claims 7 to 9, further comprising:

11. The method of claim 10 , wherein the peripheral wall confines the released coolant within an area surrounding the electronic component.

12. The heat sink further comprises: a bypass channel configured to direct coolant directly to the surface of the electronic component; 12. The method of any one of claims 7 to 11, comprising:

13. 13. The method of any of claims 7 to 12, wherein the coolant comprises a plurality of microcapsules configured to rupture at the phase change temperature of the PCM plug.

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