Assemblies and methods associated with an elastically reinforced dispensable gel

Abstract

An example thermal -interface gap filler includes: a polymeric material; a plurality of thermally-conductive particles mixed with the polymeric material; and a plurality of elastic particles interspersed within the polymeric material, wherein the plurality of elastic particles are softer and larger than the plurality of thermally-conductive particles.

Description

Assemblies and Methods Associated with an Elastically Reinforced Dispensable GelCROSS REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to U.S. Provisional Patent Application No. 63 / 674,327, filed on July 23, 2024, the entire contents of which are herein incorporated by reference as if fully set forth in this description.TECHNICAL FIELD

[0002] This disclosure relates generally to elastically reinforced dispensable gels for managing impact stresses and disturbances.BACKGROUND

[0003] Circuit designs for modem electronic devices such as televisions, radios, computers, medical instruments, business machines, communications equipment, and the like have become increasingly complex. For example, integrated circuits have been manufactured for these and other devices, and such integrated circuits contain the equivalent of hundreds of thousands of transistors. Although the complexity of the designs has increased, the size of the devices has continued to shrink with improvements in the ability to manufacture smaller electronic components and to pack more of these components in an ever smaller area.

[0004] As electronic components have become smaller and more densely packed on integrated boards and chips, designers and manufacturers have to include means for dissipating the heat generated by these components. For example, many electronic components, and especially power semiconductor components such as transistors and microprocessors, are more prone to failure ormalfunction at high temperatures. Thus, the ability to dissipate heat is often a limiting factor on the performance of the component.

[0005] Electronic components within integrated circuits traditionally have been cooled via forced or convective circulation of air within a housing of the device. In this regard, cooling fins have been provided as an integral part of the component package or as separately attached thereto for increasing the surface area of the package exposed to convectively-developed air currents. Electric fans additionally have been employed to increase the volume of air that is circulated within the housing. However, for high power circuits and the smaller but more densely packed circuits typical of current electronic designs, simple air circulation often has been found to be insufficient to adequately cool the circuit components.

[0006] Heat dissipation beyond what is attainable by simple air circulation may be achieved by the direct mounting of the electronic component to a thermal dissipation member such as a “cold plate” or other heat sink or spreader. The dissipation member may be a dedicated, thermally- conductive ceramic or metal plate, a finned structure, or simply the chassis or circuit board of the device. However, beyond the normal temperature gradients between the electronic component and the dissipation member, an appreciable temperature gradient is developed as a thermal interfacial impedance or contact resistance at the interface between the bodies.

[0007] To improve the heat transfer efficiency through the interface, a pad or other layer of a thermally-conductive, electrically-insulating material can be interposed between the heat sink and electronic component to fill in any surface irregularities and eliminate air pockets that negatively affect heat transfer. For example, a thermally-conductive material may be placed at the interface between the component and the heat sink to enhance heat transfer.

[0008] However, in some applications, the components may be subjected to impact or vibration.For example, if the electronic component is used in an electronic device, such as a receiver, placed on the roof of a house, such electronic device may be subjected to impact from hail or the like. Impact to the electronic components may cause the material to be displaced as it is squeezed out of the interface between the electronic component and the heat sink under pressure. The heat transfer capability of the material may thus deteriorate.

[0009] In some examples, thermal pads can be disposed between an electronic component and a heat sink instead of a displaceable interface material. However, placing a pad between every component and a heat sink is not efficient during manufacturing. Further, the gaps between different components and their heat sinks may be different, and thus different size pads would need to be used, further reducing manufacturing efficiency. A dispensable thermal material interface may thus be superior than a pad with respect to manufacturing flexibility.

[0010] It may thus be desirable to have a thermally-conductive dispensable material that, not only provides enhanced heat transfer properties, but also provides enhanced manufacturing flexibility and resistance to impact. It is with respect to these and other considerations that the disclosure made herein is presented.SUMMARY

[0011] The present disclosure describes implementations that relate to assemblies and methods associated with an elastically reinforced dispensable gel.

[0012] Within examples, disclosed herein is a reinforced dispensable gel that is used as a thermal interface material between an electronic component and a heat sink. In an example, the disclosed reinforced dispensable gel includes polymeric (e.g., silicon) material or binder having a ceramic filler particles that are thermally conductive. Additionally, the disclosed gel includes elastic particles interspersed within the material, where the elastic particles are softer and larger than the surrounding ceramic filler particles.

[0013] The elastic particles operate as an absorber for external stresses that would otherwise cause the material to be displaced from its original interface and fail to operate as intended. Particularly, the elastic particles operate as an elastic reinforcement for the dispensable gel that otherwise has limited elastic properties.

[0014] The disclosure also describes assemblies involving the disclosed gel. The disclosure further describes methods of forming and dispensing or using the gel.

[0015] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, implementations, and features described above, further aspects, implementations, and features will become apparent by reference to the figures and the following detailed description.BRIEF DESCRIPTION OF THE FIGURES

[0016] Figure 1 A illustrates an assembly of a heat source and a heat sink, with a thermal-interface gap filler disposed therebetween.

[0017] Figure IB illustrates the assembly of Figure 1A in a starting position before mechanical impact.

[0018] Figure 1C illustrates the assembly of Figure 1A after being subjected to an impact stress causing lateral displacement of the therm al -interface gap filler.

[0019] Figure ID illustrates the assembly of Figure 1A upon removal of mechanical impact.

[0020] Figure 2A illustrates an assembly of a heat source and a heat sink, with a thermal-interface gap filler disposed therebetween, where the thermal-interface gap filler includes elastic particles, according to an example implementation.

[0021] Figure 2B illustrates the assembly of Figure 2A in a starting position before mechanical impact, according to an example implementation.

[0022] Figure 2C illustrates the assembly of Figure 2A after being subjected to an impact stress, according to an example implementation.

[0023] Figure 2D illustrates rebounding of the thermal-interface gap filler upon removal of mechanical impact, according to an example implementation.

[0024] Figure 3 is a graph showing relative performance with and without elastic particles dispersed in a dispensable gel material, according to an example implementation.

[0025] Figure 4A illustrates a setup of an experiment with a thermal interface material interposed between an aluminum substrate and a glass substrate, according to an example implementation.

[0026] Figure 4B illustrates displacement of a standard gel under pressure, according to an example implementation.

[0027] Figure 4C illustrates displacement of a th erm al -interface gap fdler having elastic particles under pressure, according to an example implementation.

[0028] Figure 4D illustrates an enlarged view of Figure 4C to clarify rebounding of the thermalinterface gap filler, according to an example implementation.

[0029] Figure 5 is a flowchart of a method for filling a gap between a first surface and a second surface, according to an example implementation.DETAILED DESCRIPTION

[0030] Disclosed herein are assemblies and methods associated with a reinforced dispensable gel that is used as a thermal interface material between a heat source (e.g., an electronic component) and a heat sink. The disclosed reinforced dispensable gel includes polymeric (e.g., silicon) material or binder having a ceramic filler particles that are thermally conductive. Additionally, the disclosed gel includes elastic particles interspersed within the polymeric material, where the elastic particles are softer and larger than the surrounding ceramic filler particles. Examples of such elastic particles include plastic, rubber, or other elastic / elastomeric particles.

[0031] The elastic particles operate as an absorber for external stresses that would otherwise cause the material to be displaced from its original interface and fail to operate as intended. Particularly, the elastic particles operate as an elastic reinforcement for the dispensable gel that otherwise has limited elastic properties.

[0032] Figure 1A illustrates an assembly 10 of a heat source 12 and a heat sink 14, with a thermalinterface gap filler 16 disposed therebetween. The heat source 12 can be an electronic component (e.g., chip, transistor, a microprocessor, application-specific integrated chip, etc.) that generates heat during operation. The heat sink 14 can be any type of heat sink such as a finned plate, a plate with a fan mounted thereto, etc.

[0033] The thermal -interface gap filler 16 can be a dispensable gel including a base material 18 (e g., polymeric or silicon material) having thermally-conductive particles 20 as a filler dispersed therein. The thermally-conductive particles 20 can be ceramic filler particles, such as alumina or boron nitride particles, for example. This way, the thermal -interface gap filler 16 may enhance heat transfer from the heat source 12 to the heat sink 14 to control the temperature of the heatsource 12. However, the thermal-interface gap filler 16 might not be suited to handle mechanical impacts (stresses, vibration, etc.).

[0034] Figure IB illustrates the assembly 10 in a starting position before mechanical impact. During an uncontrolled, external impact event, the stresses on the assembly 10 can cause the gap to compress and then relax. A standard or ordinary dispensable gel does not have elastic properties to absorb the impact energy, so the impact pressure or force causes the thermal-interface gap filler 16 to be displaced laterally.

[0035] Figure 1C illustrates the assembly 10 after being subjected to an impact stress causing lateral displacement of the thermal-interface gap filler 16. Particularly, as shown in Figure 1C, the heat sink 14 and the heat source 12 have been moved closer to each other, e.g., due to mechanical impact or stress, reducing the gap therebetween compared to the gap shown in Figure IB prior to the impact. As a result, the thermal -interface gap filler 16 is pumped or squeezed out, laterally, from the interface between the heat source 12 and the heat sink 14.

[0036] The thermal -interface gap filler 16 is not elastic, and does not have components that render “structure” to it, and therefore upon impact and material deforms and without have the flexibility to substantially rebound back to its original state.

[0037] Figure ID illustrates the assembly 10 upon removal of mechanical impact. When the assembly 10 rebounds back to its original state upon removal of stress, and the gap between the heat source 12 and the heat sink 14 is restored, the thermal-interface gap filler 16 that has been displaced is no longer in its original position to act as a thermal-interface gap filler.

[0038] As shown in Figure ID, the gap between the heat source 12 and the heat sink 14 has been restored to its original size of Figure IB. However, although some of the thermal-interface gapfiller 16 has been restored to the interface between the heat source 12 and the heat sink 14, the thermal -interface gap filler 16 has been compromised such that some portions 22 remained outside the interface or gap, and some regions 24 of the interface are void of the thermal-interface gap filler 16. This causes deterioration in the performance of the thermal-interface gap filler 16 as a heat transfer material, which may lead to thermal runaway and failure of the heat source 12.

[0039] It may thus be desirable to have a thermal -interface gap filler that has elastic properties and that is configured to provide a physical limitation to prevent excess thermal material from being displaced. For example, the thermal-interface gap filler can be interspersed with soft, elastic material (e.g., plastic or rubber particles) that provide a physical limitation to prevent excess thermal material from being displaced laterally upon being subjected to an external impact. The soft, elastic particles act as a pseudo elastic material that provides structure to the interface material, and absorb the stress and energy of the impact.

[0040] Figure 2A illustrates an assembly 100 of a heat source 102 and a heat sink 104, with a thermal -interface gap filler 106 disposed therebetween, where the thermal -interface gap filler 106 includes elastic particles 108, according to an example implementation. The heat source 102 is similar to the heat source 12 described above and can be an electronic component (e.g., chip, transistor, a microprocessor, application-specific integrated chip, etc.) that generates heat during operation. The heat sink 104 is similar to the heat sink 14 described above and can be any type of heat sink such as a finned plate, a plate with a fan mounted thereto, etc.

[0041] Different types of thermal-interface gap fillers can be used. For example, the thermalinterface gap filler 106 can take the form of a paste comprising a mineral oil with thermally- conductive solid particles (e.g., metallic material) suspended therein. In other examples, thethermal-interface gap filler 106 can include a silicone polymer that is combined with a thermal medium (e.g., ceramic).

[0042] In an example, the thermal-interface gap filler 106 can include silicone grease or wax filled with a thermally-conductive material such as aluminum oxide. Such silicon grease can take the form of a semi-liquid or solid material at normal room temperature, and may liquefy or soften at elevated temperatures to flow and better conform to any irregularities of the interface surfaces between the heat source 102 and the heat sink 104. In some examples, the silicon greases or waxes can be provided in the form of a film.

[0043] In another example, the thermal-interface gap filler 106 can include thermally-conductive particles 110 dispersed within a polymeric material 112 (polymer gel binder material). Example polymeric materials include silicones, urethanes, thermoplastic rubbers, and other elastomers, with examples of the thermally-conductive particles 110 including aluminum oxide, magnesium oxide, zinc oxide, boron nitride, and aluminum nitride. The thermally-conductive particles 110 can form between about 10-96% by volume or 50-90% by weight of the thermal-interface gap filler 106 based on the desired heat transfer properties of the thermal-interface gap filler 106. A larger percentage of weight or volume of the thermally-conductive particles 110 may increase the heat transfer capacity of the thermal -interface gap filler 106, for example.

[0044] In an example, the thermal-interface gap filler 106 can include phase-change materials, which can be self-supporting and form-stable at room temperature for ease of handling. Such phase-change materials can liquefy or otherwise soften at temperatures within the operating temperature range of the heats source 102 to form a viscous, thixotropic phase, which can better conform to the interface surfaces between the heats source 102 and the heat sink 104.

[0045] The thermal-interface gap filler 106 is configured as a thermally-conductive compound that is dispensable under an applied pressure as issued as a bead or mass from a nozzle or other orifice. For example, the thermal-interface gap filler 106 may be charged in a tube, cartridge, or other container such that the container has a supply of the thermal -interface gap filler 106. The thermal -interface gap filler 106 can then be dispensed onto a surface of the heat source 102, which forms a gap with the heat sink 104, or dispensed directly into the gaps formed between the adjoining surfaces. This configuration of the renders the thermal -interface gap filler 106 as a dispensable gel material may enhance manufacturing efficiency and flexibility compared to traditional pads.

[0046] As applied, the thermal-interface gap filler 106 can form a bead or mass of material “in place.” Within the gap, the formed-in-place bead or mass of the thermal-interface gap filler 106 can operate as an interface material in being conformable to at least partially fill the gaps and to thereby provide a thermally-conductive pathway between the surfaces and reduce thermal resistance. In examples, the thermal-interface gap filler 106 can be fully cross-linked or otherwise cured as charged within the tube, cartridge, or other container, or as otherwise supplied.

[0047] The thermal-interface gap filler 106 can be formulated as being fluent under an applied pressure, yet form-stable as applied to a surface or within the gaps, as a blend or admixture of: (i) the polymeric material 112 configured as a gel component; and (ii) the thermally-conductive particles 110 component mixed with the polymeric material 112 and operating as a filler. The thermally-conductive particles 110 are thermally-conductive particles or a blend thereof. The gel component can be, for example, a thermoplastic gel or a silicone gel which may be an organopolysiloxane.

[0048] Gels that can be used for the polymeric material 112 may include systems based on silicones, i.e., polysiloxanes, such as polyorganosiloxane, as well as systems based on other polymers, which may be thermoplastic or thermosetting, such as polyurethanes, polyureas, fluoropolymers, chlorosulfonates, polybutadienes, butyls, neoprenes, nitrites, polyisoprenes, and buna-N, copolymers such as ethylene-propylene (EPR), styrene-isoprene-styrene (SIS), styrene- butadiene-styrene (SBS), ethylene-propylene-diene monomer (EPDM), nitrile butadiene (NBR), styrene-ethylene-butadiene (SEB), and styrene-butadiene (SBR), and blends thereof such as ethylene or propyl ene-EPDM, EPR, or NBR.

[0049] The polymeric material 112 (polymer gel) can include fluid-extended polymer system comprising a continuous polymeric phase or network, which can be chemically, e.g., ionically or covalently, or physically cross-linked, and an oil, such as a silicone or other oil, a plasticizer, unreacted monomer, or other fluid extender, which swells or otherwise fdls the interstices of the network. The cross-linking density of such network and the proportion of the extender can be controlled to tailor the modulus, i.e., softness, and other properties of the gel. The polymeric material 112 can also encompass materials that alternatively can be classified broadly as pseudogels or gel-like as having viscoelastic properties similar to gels, such has by having a “loose” cross-linking network formed by relatively long cross-link chains, but as, for example, lacking a fluid extender. Example polymer or silicone gels can include soft silicone gels.

[0050] The polymeric material 112 can be rendered thermally-conductive by loading it with the thermally-conductive particles 110 such as: noble and non-noble metals such as nickel, copper, tin, aluminum, and nickel; noble metal-plated noble or non-noble metals such as silver-plated copper, nickel, aluminum, tin, or gold; non noble metal-plated noble and non-noble metals such as nickel-plated copper or silver; and noble or non-noble metal plated non-metals such as silver or nickel- plated graphite, glass, ceramics, plastics, elastomers, or mica; and mixtures thereof.

[0051] Notably, in addition to the thermally-conductive particles 110, the thermal-interface gap fdler 106 includes the elastic particles 108 interspersed in the polymeric material 112. The elastic particles 108 are configured as soft particles and operate as an elastic reinforcement for the thermal -interface gap filler 106. Example materials for the elastic particles 108 include plastic (e g., polyethylene) and rubber (silicone, urethane, latex, ethylene propylene diene monomer, etc.).

[0052] In examples, the elastic particles 108 can represent between 1-5% by weight of the thermalinterface gap filler 106. However, the weight percentage may depend on the impact forces that the assembly 100 may be subjected to. Thus, in some applications, the elastic particles 108 may represent up to 10% of the weight of the thermal -interface gap filler 106.

[0053] Although the elastic particles 108 can be made of plastics or rubber material, rubber may be referred in some applications. Particularly, rubber may be more suitable to applications where the material may be subjected to a large number of impact cycles (cycles of compression and relaxation). Plastics may crack after a smaller number of cycles compared to rubbers.

[0054] The elastic particles 108 are configured to be larger in size than the thermally-conductive particles 110, and also slightly larger than a desired minimum gap between the heat source 102 and the heat sink 104. The term “desired minimum gap” is used herein to refer to the minimum gap during an impact event (e.g., gap 116 shown in Figure 2C) not the gap (e.g., gap 114 shown in Figure 2B, 2D) during a relaxed state prior to impact. This way, the elastic particles 108 can be configured to act as a physical limitation to prevent excess thermal material of the thermalinterface gap filler 106 from being displaced. The elastic particles 108 thus act as a pseudo elastic material that absorbs the stress and energy of impact.

[0055] The elastic particles 108 are, however, softer (more elastic or more flexible) than the thermally-conductive particles 110, which could be hard ceramic particles. Notably, the elastic particles 108 are not made of hard material (e.g., glass). While such hard material may provide a physical limit to the gap between the heat source 102 and the heat sink 104, it could damage the heat source 102, for example, upon being subjected to impact.

[0056] In an example, the elastic particles 108 are configured to have a thermal conductivity that is less than a respective thermal conductivity of the rest of the components of the thermal-interface gap filler 106 (e.g., less than a respective thermal conductivity of thermally-conductive particles 110).

[0057] non-thermally functional. In other words, the elastic particles 108 are not thermally conductive.

[0058] Although the elastic particles 108 are shown schematically as circular or spherical, other shapes and geometries (e.g., any polygonal shape) are contemplated. In examples, the elastic particles 108 can have an irregular shape. Further, the elastic particles 108 can be solid, hollow, or have a mesh structure.

[0059] In an example, the elastic particles 108 can be evenly dispersed throughout the polymeric material 112. In other examples, the elastic particles 108 can be concentrated in some regions of the polymeric material 112.

[0060] Figure 2B illustrates the assembly 100 in a starting position before mechanical impact, according to an example implementation. The thermally-conductive particles 110 are not shown in Figure 2B to reduce visual clutter in the drawings, but it should be understood that the thermal-interface gap filler 106 of Figure 2B (and Figures 2C, 2D as well) includes the thermally- conductive particles 110.

[0061] Prior to impact, a gap 114 exists between the heat source 102 and the heat sink 104, wherein the thermal-interface gap filler 106 is dispensed into and fills the gap 114. During an uncontrolled, external impact event, the stresses on the assembly 100 can cause the gap 114 to be reduced, compressing the thermal -interface gap filler 106).

[0062] Figure 2C illustrates the assembly 100 after being subjected to an impact stress, according to an example implementation. Particularly, as shown in Figure 2C, the heat sink 104 and the heat source 102 have been moved closer to each other such that a gap 116, smaller than the gap 114, exists therebetween. The gap 116 can be a desired minimum gap determined by design, and the size of the elastic particles 108 is configured to be slightly larger than the gap 116 such that as the elastic particles 108 deflect or are compressed to absorb the impact energy, the final gap between the heat source 102 and the heat sink 104 is approximately the desired minimum gap.

[0063] The assembly 100 differs from the assembly 10 in that, as the heat source 102 and the heat sink 104 are brought closer to each other due to impact and as the thermal -interface gap filler 106 is compressed, the elastic particles 108, being larger than thermally-conductive particles 110, and larger than the gap 116, deflect or deform under pressure to absorb the impact energy. However, the elastic particles 108 prevent the gap 116 between the heat sink 104 and the heat source 102 from becoming smaller than desired. In other words, the elastic particles 108 operate as a physical limitation that interacts with the heat source 102 and the heat sink 104 as shown in Figure 2C to limit the deflection or compression. As a result, a lateral displacement 118 of the thermal-interface gap filler 106 is minimized or reduced compared to the lateral displacement shown in Figure 1C.

[0064] Figure 2D illustrates rebounding of the thermal-interface gap filler 106 upon removal of mechanical impact, according to an example implementation. When the assembly 100 rebounds back to its original state, the thermal-interface gap filler 106 substantially restores its original state.

[0065] As shown in Figure 2D, the gap 114 between the heat source 12 and the heat sink 14 has been restored to its original size of Figure 2B. Most of the thermal-interface gap filler 106 has been restored to the interface between the heat source 102 and the heat sink 104, and only portions 120 (smaller than the portions 22 in Figure ID) has remained outside the interface or gap. Regions 122 void of the thermal-interface gap filler 106 are minimal or are completely eliminated.

[0066] Thus, the thermal-interface gap filler 106 may substantially maintain its performance as a heat transfer material upon being subjected to impact. In contrast with the thermal-interface gap filler 16, which deteriorates under stress, the thermal-interface gap filler 106 has elastic properties due to the presence of the elastic particles 108, and is thus able to absorb the impact energy, limiting lateral displacement, and substantially maintaining its performance as a heat transfer material.

[0067] Notably, the presence of the elastic particles 108 may reduce or dilute the thermal conductivity of the thermal -interface gap filler 106. As such, to achieve a particular thermal conductivity, the thermal-interface gap filler 106 is selected to have a higher thermal conductivity than the desired particular thermal conductivity such that when the elastic particles 108 are interspersed into the thermal-interface gap filler 106, the resulting thermal conductivity is close to the desired particular thermal conductivity.

[0068] As an example for illustration, assuming that a desired particular thermal conductivity is 5 Watts per meter-kelvin (W.irr'K1), the thermal-interface gap filler 106 can be selected to have a thermal conductivity of 7 W.m^K'1. The thermal conductivity can be controlled by the type,material, number, volume or weight percentage, shape, etc. of the thermally-conductive particles 110. This way, including the elastic particles 108 into the thermal-interface gap filler 106 may reduce the thermal conductivity to the desired 5 W.m^K'1while ascribing the elastic properties described above, rendering the thermal-interface gap filler 106 more effective under mechanical stress.

[0069] An experiment has been conducted to demonstrate the effectiveness of the thermalinterface gap filler 106 having the elastic particles 108. In this experiment, the thermal-interface gap filler 106 includes a silicon polymer as the polymeric material 112 and includes alumina filler particles as the thermally-conductive particles 110. The average size of the alumina filler particles ranged between 10 micrometer (pm) and 175 pm in diameter. The thermal-interface gap filler 106 is selected to be a 5 W.m^K'1thermal interface material.

[0070] In the experiment, the elastic reinforcement particles (the elastic particles 108) are configured as polyethylene microspheres ranging in size between 212 pm and 250 pm in diameter. Thus, the elastic particles 108 were approximately 100 pm larger than the thermally-conductive particles 110. The elastic particles 108 have been loaded into the thermal -interface gap filler 106 such that the elastic particles 108 represent 1.5% by weight of the thermal-interface gap filler 106.

[0071] The performance of a dispensable gel without the elastic particles has been compared to the performance of the thermal -interface gap filler 106 including the elastic particles 108. Particularly, a dispensable gel without elastic particles has been placed between two surfaces, and then pressure has been applied to the plates to squeeze them together with a gradually increasing pressure, reducing the gap therebetween. The experiment has then been repeated using the thermal-interface gap filler 106 including the elastic particles 108.

[0072] Figure 3 is a graph 200 showing relative performance with and without elastic particles dispersed in a dispensable gel material, according to an example implementation. The x-axis represents the gap thickness between the two surfaces in millimeter (mm) and the y-axis represents the compression pressure being applied to the surfaces in pounds per square inch (psi). Line 202 represents performance of a standard thermal interface gel (“Std GEL”) that does not have elastic particles, and line 204 represents performance of the thermal -interface gap filler 106 including the elastic particles 108 (“IMPACT GEL”).

[0073] Tracing the lines 202, 204 from right to left, the gap between the surfaces that have the respective thermal interface material disposed therebetween is reduced as the pressure applied thereto is increased. For example, referring to the line 202, in the portion shown in Figure 3, the gap at the right most point is 0.5 mm at a pressure of about 2-3 psi.

[0074] As the pressure is increased, the gap is decreased until the gap becomes about 0.275 mm at point 206 at which the thermally-conductive particles 110 start to “stack” (contact or become squeezed against each other). Thus, at the point 206, the resistance to the pressure needed to reduce the gap increases more substantially. Between the point 206 and point 208, which corresponds to a gap of about 0.235 mm, is a region 210 that can be referred to as “primary particle stacking”, in which the stacked particles may slip, give way, and move relative to each other, causing the gap to continue to be reduced, albeit irregularly, as the pressure is increased.

[0075] However, at the point 208, stacking of the thermally-conductive particles 110 reaches a point at which they no longer can significantly slip or give way. Thereafter, the pressure increase asymptotically and the corresponding decrease in the gap size is minimal.

[0076] As shown in the graph 200, the line 204 is generally shifted upward relative to the line 202, indicating the effect of including the elastic particles 108 into the thermal -interface gap filler 106.Particularly, including the elastic particles 108 into the thermal-interface gap filler 106 causes the pressure level to achieve a particular gap to increase compared to the standard gel. This is particularly amplified in the primary particle stacking region as shown in the graph 200.

[0077] In particular, at point 212 of the line 204 (where the point 212 corresponds to the point 206 of the line 202), the surfaces being squeezed by the pressure reach and interact with the elastic particles 108 first due to their larger size compared to the thermally-conductive particles 110 (see Figure 2C). Thus, prior to reaching the point at which stacking of the thermally-conductive particles 110 occurs, the elastic particles 108 (the polyethylene microspheres in this experiment) absorb and distribute the force.

[0078] Comparing the point 206 to the point 212, it takes a pressure that is up to 450% (e.g., between 8 psi and 37 psi) larger pressure to achieve a gap of about 0.275 mm when using the thermal -interface gap filler 106 (including the elastic particles 108) compared to the pressure that achieves the same gap with the standard gel. The maximum pressure differential is achieved at point 214 of the line 204 (where the point 214 corresponds to the point 208 of the line 202). Particularly, a maximum absorption / distribution of greater than 350% (e.g., 15 psi to 55 psi) pressure is observed at the point 214 compared to the point 208.

[0079] Thus, the graph 200 demonstrates the effect of including the elastic particles 108 in the thermal -interface gap filler 106, causing absorption and distribution of external forces / pressures relative to the standard gel. For a given external force / pressure, an assembly having the thermalinterface gap filler 106 with the elastic particles 108 is not squeezed (the gap is not reduced) as much as in an assembly with a standard gel. As such, the thermal-interface gap filler 106 is not displaced outward by as much as a standard gel. This indicates the enhanced capability of the thermal -interface gap filler 106 having the elastic particles 108 in resisting external impact forces,thereby maintaining performance of the thermal-interface gap filler 106 under external impact forces.

[0080] Another experiment has been conducted to measure the effect of cycling (compressing and relaxing) on the thermal-interface gap filler 106 compared to a standard gel. The experiment also demonstrates the enhancement that the thermal -interface gap filler 106 having the elastic particles 108 provides in reducing displacement of the thermal interface material under stress.

[0081] Figure 4A illustrates a setup of an experiment with a thermal interface material 300 interposed between an aluminum substrate 302 and a glass substrate 304, according to an example implementation. The aluminum substrate 302 is at the bottom, while the glass substrate 304 on top to reveal the state of the thermal interface material 300.

[0082] As shown, the thermal interface material 300 is provided in the form of a disk. Dots 306 are marked on the glass substrate to mark the circular boundary of the thermal interface material 300. The initial gap between the aluminum substrate 302 and the glass substrate 304 is set to 0.3 mm. The thermal interface material 300 initially dispensed is a standard gel without elastic particles. An impact pressure of 100 psi is then applied cyclically (On and Off), thus squeezing and relaxing the thermal interface material 300 (standard gel), for ten cycles. The experiment is then repeated with the thermal interface material 300 being the thermal-interface gap filler 106 having the elastic particles 108.

[0083] Figure 4B illustrates displacement of a standard gel 400 under pressure, according to an example implementation. As shown, after ten cycles, a significant material displacement of the standard gel 400 has occurred. Particularly, about 50% of the material has been displaced. This can be seen by comparing an perimeter 402 of the standard gel 400 after displacement compared to a circle that connects the dots 306 defining the initial state of the standard gel 400 prior toapplication of pressure. Further, after the cycling has ended, the displaced material substantially remains outside the dots 306 and does not rebound to its original state.

[0084] Figure 4C illustrates displacement of the thermal-interface gap filler 106 having the elastic particles 108 under pressure, according to an example implementation. As shown, after ten cycles, about a 24% material displacement of the thermal-interface gap filler 106 has occurred. This can be seen by comparing an perimeter 404 of the thermal-interface gap filler 106 after displacement compared to the circle that connects the dots 306 defining the initial state of the thermal-interface gap filler 106 prior to application of pressure.

[0085] The displacement of the thermal-interface gap filler 106 is thus about half of the material displacement of the standard gel 400. This can be seen by comparing the perimeter 404 of the thermal -interface gap filler 106 relative to the dots 306 as shown in Figure 4C to the perimeter 402 of the standard gel 400 relative to the dots 306 as shown in Figure 4B.

[0086] Figure 4D illustrates an enlarged view of Figure 4C to clarify rebounding of the thermalinterface gap filler 106, according to an example implementation. Figure 4D demonstrates rebounding of the thermal-interface gap filler 106 after the cycling has stopped.

[0087] Particularly, while the thermal-interface gap filler 106 has been displaced to an perimeter 406 during cycling, upon stopping application of pressure, a substantial amount of the thermalinterface gap filler 106 has rebounded (due to flexibility of the elastic particles 108 and their ability to absorb and distribute the pressure) to an perimeter 408, which substantially coincides with the dots 306. This leaves a “halo” between the perimeter 408 and the perimeter 406. As a substantial amount of the thermal-interface gap filler 106 has rebounded to the perimeter 406, minimal loss of performance of the thermal -interface gap filler 106 and its ability to transfer heat may take place, despite being subjected to impact pressures.

[0088] Figure 5 is a flowchart of a method 500 for filling a gap between a first surface and a second surface, according to an example implementation. For example, the method 500 can be used for filling the gap 114 between the heat source 102 and the heat sink 104 using the thermal -interface gap filler 106.

[0089] The method 500 may include one or more operations, or actions as illustrated by one or more of blocks 502-504. Although the blocks are illustrated in a sequential order, these blocks may in some instances be performed in parallel, and / or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and / or removed based upon the desired implementation.

[0090] At block 502, the method 500 includes forming the gap 114 between the heat source 102 and the heat sink 104.

[0091] At block 504, the method 500 includes dispensing the thermal-interface gap filler 106 into the gap 114, wherein the thermal-interface gap filler comprises the polymeric material 112, the thermally-conductive particles 110 mixed with the polymeric material 112, and the elastic particles 108 interspersed within the polymeric material 112, wherein the elastic particles 108 are softer and larger than the thermally-conductive particles 110, and wherein the elastic particles 108 are larger than a minimum desired gap between the heat source 102 and the heat sink 104. The thermalinterface gap filler 106 can be dispensed under pressure from a container (configured as a storage for the thermal-interface gap filler 106) through a nozzle that is in fluid communication with the container. The dispensation can occur manually or via a robotic, automated process in a manufacturing environment.

[0092] The method 500 can further include any of the steps described above.

[0093] The detailed description above describes various features and operations of the disclosed systems with reference to the accompanying figures. The illustrative implementations described herein are not meant to be limiting. Certain aspects of the disclosed systems can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein.

[0094] Further, unless context suggests otherwise, the features illustrated in each of the figures may be used in combination with one another. Thus, the figures should be generally viewed as component aspects of one or more overall implementations, with the understanding that not all illustrated features are necessary for each implementation.

[0095] Additionally, any enumeration of elements, blocks, or steps in this specification or the claims is for purposes of clarity. Thus, such enumeration should not be interpreted to require or imply that these elements, blocks, or steps adhere to a particular arrangement or are carried out in a particular order.

[0096] Further, devices or systems may be used or configured to perform functions presented in the figures. In some instances, components of the devices and / or systems may be configured to perform the functions such that the components are actually configured and structured (with hardware and / or software) to enable such performance. In other examples, components of the devices and / or systems may be arranged to be adapted to, capable of, or suited for performing the functions, such as when operated in a specific manner.

[0097] By the term “substantially” or “about” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those with skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0098] The arrangements described herein are for purposes of example only. As such, those skilled in the art will appreciate that other arrangements and other elements (e.g., machines, interfaces, operations, orders, and groupings of operations, etc.) can be used instead, and some elements may be omitted altogether according to the desired results. Further, many of the elements that are described are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location.

[0099] While various aspects and implementations have been disclosed herein, other aspects and implementations will be apparent to those skilled in the art. The various aspects and implementations disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope being indicated by the following claims, along with the full scope of equivalents to which such claims are entitled. Also, the terminology used herein is for the purpose of describing particular implementations only, and is not intended to be limiting.

[0100] Embodiments of the present disclosure can thus relate to one of the enumerated example embodiments (EEEs) listed below.

[0101] EEE 1 is a thermal-interface gap fdler comprising: a polymeric material; a plurality of thermally-conductive particles mixed with the polymeric material; and a plurality of elastic particles interspersed within the polymeric material, wherein the plurality of elastic particles are softer and larger than the plurality of thermally-conductive particles.

[0102] EEE 2 is the thermal -interface gap fdler of EEE 1, wherein the plurality of elastic particles comprise plastic or rubber particles.

[0103] EEE 3 is the thermal-interface gap fdler of any of EEEs 1-2, wherein the plurality of elastic particles comprise polyethylene microspheres.

[0104] EEE 4 is the thermal-interface gap filler of any of EEEs 1 -3, wherein the plurality of elastic particles comprise 1-10% weight of the thermal -interface gap filler.

[0105] EEE 5 is the thermal-interface gap filler of any of EEEs 1-4, wherein the polymeric material is configured as a gel.

[0106] EEE 6 is the thermal-interface gap filler of any of EEEs 1 -5, wherein the plurality of thermally-conductive particles comprise aluminum oxide, magnesium oxide, zinc oxide, boron nitride, aluminum nitride, silicon carbide, diamond, or a mix thereof.

[0107] EEE 7 is the thermal-interface gap filler of any of EEEs 1-6, wherein the plurality of thermally-conductive particles represent between 20-96% weight of the thermal-interface gap filler.

[0108] EEE 8 is the thermal-interface gap filler of any of EEEs 1-7, wherein an average size of the plurality of thermally-conductive particles ranges between 10 micrometer (|j.m) and 175 pm in diameter, and wherein a respective average size of the plurality of elastic particles ranges between 212 pm and 250 pm.

[0109] EEE 9 is an assembly comprising: a heat source; a heat sink facing the heat source such that a gap is formed between the heat source and the heat sink; and the thermal-interface gap filler of any of EEEs 1-8 disposed in the gap between the heat source and the heat sink. For example, the thermal-interface gap filler comprises: a polymeric material, a plurality of thermally- conductive particles mixed with the polymeric material, and a plurality of elastic particles interspersed within the polymeric material, wherein the plurality of elastic particles are softer and larger than the plurality of thermally-conductive particles, and wherein the plurality of elastic particles are larger than a minimum desired gap between the heat source and the heat sink.

[0110] EEE 10 is the assembly of EEE 9, wherein the plurality of elastic particles comprise plastic or rubber particles.

[0111] EEE 11 is the assembly of any of EEEs 9-10, wherein the plurality of elastic particles comprise polyethylene microspheres.

[0112] EEE 12 is the assembly of any of EEEs 9-11, wherein the plurality of elastic particles comprise 1-10% weight of the thermal -interface gap filler.

[0113] EEE 13 is the assembly of any of EEEs 9-12, wherein the polymeric material is configured as a gel.

[0114] EEE 14 is the assembly of any of EEEs 9-13, wherein the plurality of thermally- conductive particles comprise aluminum oxide, magnesium oxide, zinc oxide, boron nitride, aluminum nitride, silicon carbide, diamond, or a mix thereof.

[0115] EEE 15 is the assembly of any of EEEs 9-14, wherein the plurality of thermally- conductive particles represent between 20-96% weight of the thermal-interface gap filler.

[0116] EEE 16 is the assembly of any of EEEs 9-15, wherein an average size of the plurality of thermally-conductive particles ranges between 10 micrometer (gm) and 175 gm in diameter, and wherein a respective average size of the plurality of elastic particles ranges between 212 gm and 250 pm.

[0117] EEE 17 is a method of forming the assembly of any of EEEs 9-16. For example, the method comprises: forming a gap between a heat source and a heat sink; and dispensing the thermal-interface gap filler of any of EEEs 1-8 into the gap. For example, the thermal-interface gap filler comprises: a polymeric material, a plurality of thermally-conductive particles mixed with the polymeric material, and a plurality of elastic particles interspersed within the polymericmaterial, wherein the plurality of elastic particles are softer and larger than the plurality of thermally-conductive particles, and wherein the plurality of elastic particles are larger than a minimum desired gap between the heat source and the heat sink.

[0118] EEE 18 is the method of EEE 17, further comprising: providing a supply of the thermalinterface gap fdler; and providing an orifice in fluid communication with the supply, wherein dispensing the thermal-interface gap filler comprises dispensing the thermal-interface gap filler from the orifice under pressure.

[0119] EEE 19 is the method of any of EEEs 17-18, wherein dispensing the thermal-interface gap filler into the gap comprises dispensing the thermal-interface gap filler having the plurality of elastic particles configured as plastic or rubber particles, wherein the plurality of elastic particles comprise 1-10% weight of the thermal -interface gap filler.

[0120] EEE 20 is the method of any of EEEs 17-19, wherein dispensing the thermal-interface gap filler into the gap comprises dispensing the thermal-interface gap filler having the plurality of elastic particles configured as polyethylene microspheres.

Claims

CLAIMSWhat is claimed is:1 . A thermal-interface gap filler comprising: a polymeric material; a plurality of thermally -conductive particles mixed with the polymeric material; and a plurality of elastic particles interspersed within the polymeric material, wherein the plurality of elastic particles are softer and larger than the plurality of thermally-conductive particles.

2. The thermal-interface gap filler of claim 1, wherein the plurality of elastic particles comprise plastic or rubber particles.

3. The thermal-interface gap filler of claim 1, wherein the plurality of elastic particles comprise polyethylene microspheres.

4. The thermal-interface gap filler of claim 1, wherein the plurality of elastic particles comprise 1-10% weight of the thermal-interface gap filler.

5. The thermal-interface gap filler of claim 1, wherein the polymeric material is configured as a gel.

6. The th erm al -interface gap filler of claim 1, wherein the plurality of thermally- conductive particles comprise aluminum oxide, magnesium oxide, zinc oxide, boron nitride, aluminum nitride, silicon carbide, diamond, or a mix thereof.

7. The thermal-interface gap filler of claim 1, wherein the plurality of thermally- conductive particles represent between 20-96% weight of the thermal-interface gap filler.

8. The thermal -interface gap filler of claim 1, wherein an average size of the plurality of thermally-conductive particles ranges between 10 micrometer (pm) and 175 pm in diameter, and wherein a respective average size of the plurality of elastic particles ranges between 212 pm and 250 pm.

9. An assembly comprising: a heat source; a heat sink facing the heat source such that a gap is formed between the heat source and the heat sink; and a thermal -interface gap filler disposed in the gap between the heat source and the heat sink, wherein the thermal-interface gap filler comprises: a polymeric material, a plurality of thermally-conductive particles mixed with the polymeric material, and a plurality of elastic particles interspersed within the polymeric material, wherein the plurality of elastic particles are softer and larger than the plurality of thermally-conductive particles, and wherein the plurality of elastic particles are larger than a minimum desired gap between the heat source and the heat sink.

10. The assembly of claim 9, wherein the plurality of elastic particles comprise plastic or rubber particles.

11. The assembly of claim 9, wherein the plurality of elastic particles comprise polyethylene microspheres.

12. The assembly of claim 9, wherein the plurality of elastic particles comprise 1-10% weight of the thermal-interface gap filler.

13. The assembly of claim 9, wherein the polymeric material is configured as a gel.

14. The assembly of claim 9, wherein the plurality of thermally-conductive particles comprise aluminum oxide, magnesium oxide, zinc oxide, boron nitride, aluminum nitride, silicon carbide, diamond, or a mix thereof.

15. The assembly of claim 9, wherein the plurality of thermally-conductive particles represent between 20-96% weight of the thermal -interface gap filler.

16. The assembly of claim 9, wherein an average size of the plurality of thermally- conductive particles ranges between 10 micrometer (pm) and 175 pm in diameter, and wherein a respective average size of the plurality of elastic particles ranges between 212 pm and 250 pm.

17. A method comprising: forming a gap between a heat source and a heat sink; and dispensing a thermal-interface gap filler into the gap, wherein the thermal-interface gap filler comprises: a polymeric material, a plurality of thermally-conductive particles mixed with the polymeric material, and a plurality of elastic particles interspersed within the polymeric material, wherein the plurality of elastic particles are softer and larger than the plurality of thermally- conductive particles, and wherein the plurality of elastic particles are larger than a minimum desired gap between the heat source and the heat sink.

18. The method of claim 17, further comprising: providing a supply of the thermal-interface gap filler; and providing an orifice in fluid communication with the supply, wherein dispensing the thermal-interface gap filler comprises dispensing the thermal-interface gap filler from the orifice under pressure.

19. The method of claim 17, wherein dispensing the thermal-interface gap filler into the gap comprises dispensing the thermal-interface gap filler having the plurality of elastic particles configured as plastic or rubber particles, wherein the plurality of elastic particles comprise 1-10% weight of the thermal-interface gap filler.

20. The method of claim 17, wherein dispensing the thermal-interface gap filler into the gap comprises dispensing the thermal-interface gap filler having the plurality of elastic particles configured as polyethylene microspheres.

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