THERMAL INTERFACE MATERIALS, INTEGRATED CIRCUIT FORMED THEREWITH, AND METHODS OF APPLICATION THEREOF - Patent application

Abstract

A thermal interface material, an integrated circuit formed therewith, and a method of applying the same are provided. The thermal interface material includes 5% to 30% by volume of a polymer component and at least 70% by volume of liquid metal droplets, all based on the total volume of the thermal interface material. The polymer component includes a first polymer having a molecular weight in the range of 400 g / mol to 400,000 g / mol. The liquid metal droplets are dispersed throughout the polymer component.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 482,449, filed January 31, 2023, the contents of which are incorporated herein by reference.

[0002] FIELD OF THE DISCLOSURE The present disclosure relates to thermal interface materials, integrated circuits formed therewith, and methods of application thereof. [Background technology]

[0003] Thermal interface materials (TIMs) can be used to thermally connect two or more layers together. For example, TIMs are often used in CPU packages to thermally connect the CPU package's integrated heat spreader (IHS) to a heat sink. Various types of TIMs exist and can be used. However, certain TIMs used present challenges. Summary of the Invention

[0004] In one general aspect, the present disclosure is directed to a thermal interface material including 5% to 30% by volume of a polymer component and at least 70% by volume of liquid metal droplets, all based on the total volume of the thermal interface material. The polymer component has a first polymer having a molecular weight in the range of 400 g / mol to 400,000 g / mol. The liquid metal droplets are dispersed throughout the polymer component.

[0005] The present disclosure is directed to a thermal interface material comprising 5% to 30% by volume of a polymer component and at least 70% by volume of liquid metal droplets, all based on the total volume of the thermal interface material. The polymer component can include a polyalkylene glycol having a molecular weight in the range of 400 g / mol to 4,000 g / mol. The liquid metal droplets are dispersed throughout the polymer component. In various examples, the polyalkylene glycol includes at least one of polyethylene glycol, polypropylene glycol, polybutylene glycol, and copolymers thereof, e.g., polypropylene glycol. In certain examples, the polymer component further includes a second polymer that can be miscible with the polyalkylene glycol. For example, the second polymer can include at least one of an epoxy polymer, an acrylate polymer, a vinyl polymer, and a silicon hydride polymer, e.g., an epoxy polymer containing hydroxyl end groups. In certain examples, the polymer component is configured to extend the polymer chains of the second polymer in response to heating to a temperature of at least 50°C.

[0006] The present invention can provide both low contact resistance at the material interface and low thermal resistance through the TIM. Low contact resistance can be enabled by application of a polymer in a conformable state, such that the polymer and liquid metal droplets can conform to the surface of the layer to achieve the desired contact resistance. Low thermal resistance through the TIM can be enabled by the liquid metal droplets. The TIM can be removable, such that the TIM can be used during testing of the component and / or can allow replacement of the component as desired. These and other advantages realizable from various embodiments of the present invention will be apparent from the description below. [Brief explanation of the drawings]

[0007] The features and advantages of various embodiments of the present invention, as well as the manner in which they are achieved, will become more apparent and the embodiments will be better understood by reference to the following description of exemplary embodiments taken in conjunction with the accompanying drawings.

[0008] [Figure 1] FIG. 2 is a perspective view of a circuit assembly according to the present disclosure after deposition of a thermal interface material. [Figure 2] 2 is a side view of an integrated circuit formed by compressing the circuit assembly of FIG. 1;

[0009] Corresponding reference characters indicate corresponding parts throughout the several views. The examples described herein illustrate certain particular embodiments in one form, and such examples should not be construed as limiting the scope of the embodiments in any way. DETAILED DESCRIPTION OF THE INVENTION

[0010] Certain exemplary embodiments of the present invention are described herein to provide a general understanding of the principles and methods of the compositions, functions, manufacture, and use of the compositions disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the compositions, articles, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments, and that the scope of various examples of the present invention is defined only by the claims. Features illustrated or described in connection with one exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are intended to be within the scope of the present invention.

[0011] Applying a thermal interface material (TIM) to a circuit assembly, such as one between an integrated heat spreader (IHS) and a heat sink, can require balancing the thermal resistance through the TIM with the contact resistance at the material interface. For example, a polymeric material may have low contact resistance at the material interface but high thermal resistance through the material. A solid metal may have low thermal resistance through the material but high contact resistance at the material interface. In addition, some solid materials (polymer or metal) may require significant pressure during installation to achieve the desired contact resistance. Furthermore, it may be desirable to remove the TIM after application so that the TIM can be used for component testing and / or component replacement.

[0012] Therefore, the present inventors provide, in various examples, a thermal interface material, an integrated circuit formed therewith, and a method of application thereof that can achieve effective thermal conductivity of the TIM while enabling efficient removal of the TIM after installation. The TIM includes 5% to 30% by volume of a polymer component, based on the total volume of the thermal interface material, and at least 70% by volume of liquid metal droplets, based on the total volume of the thermal interface material. The liquid metal droplets are dispersed throughout the polymer component. The polymer component includes a first polymer having a molecular weight within a range of 400 g / mol to 400,000 g / mol, such as 400 g / mol to 200,000 g / mol, 400 g / mol to 100,000 g / mol, 400 g / mol to 50,000 g / mol, 400 g / mol to 10,000 g / mol, or 400 g / mol to 4,000 g / mol. The molecular weight can be measured using gel permeation chromatography. As used herein, "molecular weight" refers to the number average molecular weight, M n Represents.

[0013] As used herein, the terms "polymer" and "polymeric" refer to prepolymers, oligomers, and both homopolymers and copolymers. As used herein, "prepolymer" refers to a polymer precursor capable of further reaction or polymerization through a reactive group or groups to form higher molecular weight or crosslinked states.

[0014] The first polymer can be at least one of a polymeric binder, a thermosetting polymer, and a thermoplastic polymer. As used herein, the term "thermoset" refers to a polymer that irreversibly "sets" upon curing or crosslinking, where the polymer chains of the polymeric components are bonded together by covalent bonds, which are often induced, for example, by heat or radiation. In various examples, the curing or crosslinking reaction can be carried out under ambient conditions. Once cured or crosslinked, a thermosetting polymer may not flow upon application of heat, may irreversibly increase in viscosity, and / or may be insoluble in conventional solvents. As used herein, the term "thermoplastic" refers to a polymer comprising polymeric components whose constituent polymer chains are not bonded (e.g., crosslinked) by covalent bonds, thereby allowing for liquid flow upon heating and being soluble in conventional solvents. In certain embodiments, the polymer can be elastomeric (e.g., rubbery, soft, stretchy) or rigid (e.g., glassy). For example, the polymer can be an elastomer.

[0015] The thermosetting polymer may include at least one of a crosslinking agent, which may include, for example, aminoplasts, polyisocyanates (including blocked isocyanates), polyepoxides, beta-hydroxyalkylamides, polyacids, anhydrides, organometallic acid-functional materials, polyamines, polyvinyls, hydrogenated polysilicones, polyalcohols, polyacid chlorides, polyhalides, and polyamides. The polymer may have functional groups that react with the crosslinking agent.

[0016] The thermosetting polymer may include at least one of an acrylic polymer, an acrylate polymer, a vinyl polymer, a polyester polymer, a polyurethane polymer, a polybutadiene, a polyamide polymer, a polyether polymer, a polysiloxane polymer (e.g., poly(dimethylsiloxone)), a silicon hydride polymer, a fluoropolymer, a polyisoprene polymer (e.g., rubber), and copolymers thereof. The functional group on the thermosetting polymer may be selected from any of a variety of reactive functional groups including, for example, at least one of a carboxylic acid group, an amine group, an epoxide group, a hydroxyl group, a thiol group, a carbamate group, an amide group, a urea group, an isocyanate group (including blocked isocyanate groups), a vinyl group, a silicon hydride group, an acid chloride group, an acrylate group, a halide group, and a mercaptan group.

[0017] In various examples, the first polymer includes a polyether polymer, such as, for example, a polyalkylene glycol. The polyalkylene glycol can include at least one of polyethylene glycol, polypropylene glycol, polybutylene glycol, and copolymers thereof. For example, the polyalkylene glycol can include polypropylene glycol.

[0018] As used herein, the terms "cure" and "hardening" refer to the chemical cross-linking of components in an emulsion or material applied onto a substrate, or an increase in viscosity of the components in an emulsion or material applied onto a substrate. Thus, the terms "cure" and "hardening" do not encompass only the physical drying of an emulsion or material through solvent or carrier evaporation. In this regard, when used herein in examples involving thermosetting polymers, the term "hardened" refers to the state of an emulsion or material in which the components of the emulsion or material have chemically reacted to form new covalent bonds within the emulsion or material (e.g., new covalent bonds formed between the binder resin and the hardener).

[0019] The thermoplastic polymer can include at least one of a propylene-ethylene copolymer, a styrene-butadiene-styrene, and a styrene ethylene butylene styrene. The polymer can include a melting point of at least 100 degrees Celsius, such as at least 120 degrees Celsius, at least 150 degrees Celsius, or at least 200 degrees Celsius.

[0020] The polymeric binder may be a polyether binder.

[0021] In various examples, the polymer component can include a second polymer. The second polymer can be miscible with the first polymer. For example, the second polymer can be miscible with a polyalkylene glycol. The second polymer can include at least one of an epoxy polymer, an acrylate polymer, a vinyl polymer, and a silicon hydride polymer. For example, the second polymer can include an epoxy polymer including a hydroxyl end group, such as a polyalkylene glycol diglycidyl ether.

[0022] The polymer component can include a composition suitable for efficient removal of the TIM after installation while achieving effective thermal conductivity during use. For example, the polymer component can include 1 wt % to 50 wt % of a first polymer and 50 wt % to 99 wt % of a second polymer, all based on the total weight of the polymer component. In various examples, the polymer component can include 5 wt % to 30 wt % of the first polymer and 70 wt % to 95 wt % of the second polymer, all based on the total weight of the polymer component. In certain examples, the polymer component can include 1 wt % to 50 wt % of a polyalkylene glycol and 50 wt % to 99 wt % of a polyalkylene glycol diglycidyl ether, or 5 wt % to 30 wt % of a polyalkylene glycol and 70 wt % to 95 wt % of a polyalkylene glycol diglycidyl ether, all based on the total weight of the polymer component.

[0023] The polymeric components can be configured to cure at a temperature of at least 50 degrees Celsius, e.g., at least 60 degrees Celsius, at least 70 degrees Celsius, at least 80 degrees Celsius, at least 90 degrees Celsius, etc. For example, the polymeric components can be configured to cure at a temperature within a range of 50 degrees Celsius to 150 degrees Celsius, e.g., 60 degrees Celsius to 120 degrees Celsius, etc. For example, the second polymeric component can be configured to chain extend in response to heating to a temperature of at least 50 degrees Celsius. Chain extension of the second polymer can increase the molecular weight of the second polymer, thereby increasing the viscosity of the TIM.

[0024] Liquid metal droplets for the TIM can include at least one of gallium, gallium alloy, indium, indium alloy, tin, tin alloy, mercury, and mercury alloy. The liquid metal droplets can include a melting point of 30 degrees Celsius or less, such as 25 degrees Celsius or less, 20 degrees Celsius or less, 15 degrees Celsius or less, 10 degrees Celsius or less, 5 degrees Celsius or less, 0 degrees Celsius or less, or -10 degrees Celsius or less. The liquid metal droplets can include a melting point of at least -40 degrees Celsius, such as at least -20 degrees Celsius, at least -19 degrees Celsius, at least -10 degrees Celsius, at least 0 degrees Celsius, at least 5 degrees Celsius, at least 10 degrees Celsius, at least 15 degrees Celsius, at least 20 degrees Celsius, or at least 25 degrees Celsius. The liquid metal droplets can include a melting point in a range of -40 degrees Celsius to 30 degrees Celsius, such as -20 degrees Celsius to 30 degrees Celsius, -19 degrees Celsius to 30 degrees Celsius, or -19 degrees Celsius to 25 degrees Celsius. The melting point determination can be performed at a pressure of 1 atmosphere absolute. In one particular embodiment, the TIM can include gallium indium tin (Galinstan) and a melting point of -19 degrees Celsius.

[0025] The TIM can be made by forming an emulsion of a polymer and liquid metal droplets such that the liquid metal droplets are dispersed substantially throughout the polymer. For example, the polymer and bulk liquid metal can be mixed together in a high shear mixer, centrifugal mixer, by shaking in a container, with a mortar and pestle, or by sonication. More details regarding exemplary methods for forming emulsions and liquid metal droplets can be found in: (1) published PCT WO / 2019 / 136252, entitled "Method of Synthesizing a Thermally Conductive and Stretchable Polymer Composite," (2) published U.S. application Ser. No. 2017 / 0218167, entitled "Polymer Composite with Liquid Phase Metal Inclusions," (3) U.S. Patent No. 10,777,483, entitled "Method, apparatus, and assembly for thermally connecting layers," (4) U.S. Provisional Patent No. 63 / 268,134, entitled "Thermal interface material, an integrated circuit assembly, and a method for thermally connecting layers," (5) published PCT WO 2022 / 204689, entitled "A method, apparatus, and assembly for thermally connecting layers with thermal interface materials comprising rigid particles," and (6) "A method of manufacture of a No. 63 / 479,879, entitled "Thermal Interface Material, a Thermal Interface Material Formed Therefrom, and an Integrated Circuit Formed Therefrom," all of which are incorporated herein by reference in their entireties.

[0026] The composition and / or mixing technique can be selected to provide a viscosity of less than 850,000 cP (centipoise), e.g., less than 750,000 cP, less than 500,000 cP, less than 250,000 cP, less than 200,000 cP, less than 150,000 cP, less than 100,000 cP, less than 50,000 cP, less than 15,000 cP, less than 14,000 cP, less than 13,000 cP, less than 12,000 cP, less than 11,000 cP, or less than 10,000 cP, etc. For example, the composition and / or mixing technique can be selected to provide a viscosity of the TIM of at least 1,000 cP, e.g., at least 2,000 cP, at least 5,000 cP, or at least 10,000 cP, etc. The composition and / or mixing technique can be selected so that the viscosity of the TIM is within the range of 1,000 cP to 850,000 cP, such as 2,000 cP to 750,000 cP, or 2,000 cP to 500,000 cP. The viscosity of the TIM emulsion can be measured with a parallel plate (40 mm) rheometer at 25 degrees Celsius, a frequency of 10 radians per second, and 5% strain. Selecting a viscosity can require a balance between installation pressure, which can increase with higher viscosities, and the TIM's ability to resist undesirable rapid spreading during application and pump-out during operation.

[0027] The TIM can comprise at least 1% liquid metal droplets by total volume of the TIM, for example, at least 5% liquid metal droplets, at least 10% liquid metal droplets, at least 20% liquid metal droplets, at least 30% liquid metal droplets, at least 40% liquid metal droplets, at least 50% liquid metal droplets, at least 60% liquid metal droplets, at least 70% liquid metal droplets, at least 80% liquid metal droplets, or at least 90% liquid metal droplets, all based on the total volume of the liquid metal droplets. The TIM can comprise 95% or less liquid metal droplets by total volume of the TIM, e.g., 93% or less liquid metal droplets, 90% or less liquid metal droplets, 80% or less liquid metal droplets, 70% or less liquid metal droplets, 60% or less liquid metal droplets, 50% or less liquid metal droplets, 40% or less liquid metal droplets, 30% or less liquid metal droplets, 20% or less liquid metal droplets, or 10% or less liquid metal droplets, all based on the total volume of the TIM. The TIM can comprise a range of 1% to 95% by total volume of the TIM, e.g., 5% to 93% liquid metal droplets, 50% to 93% liquid metal droplets, 60% to 93% liquid metal droplets, 70% to 95% liquid metal droplets, or 70% to 93% liquid metal droplets, all based on the total volume of the TIM. The amount of liquid metal droplets can be selected to balance the desired elasticity and effective thermal conductivity of the TIM.

[0028] The composition and / or mixing technique may be adjusted to achieve the desired D of the liquid metal droplets in the TIM before compression. 50 and / or D. 90 The D of the liquid metal droplet can be selected to achieve 50 can be at least 1 micron before compression, e.g., at least 5 microns, at least 10 microns, at least 15 microns, at least 20 microns, at least 30 microns, at least 35 microns, at least 40 microns, at least 50 microns, at least 60 microns, at least 70 microns, at least 80 microns, at least 90 microns, at least 100 microns, at least 120 microns, at least 150 microns, or at least 200 microns, all before compression. 50can be 300 microns or less, all before compression, for example, 250 microns or less, 200 microns or less, 150 microns or less, 120 microns or less, 100 microns or less, 90 microns or less, 80 microns or less, 70 microns or less, 60 microns or less, 50 microns or less, 40 microns or less, 35 microns or less, 30 microns or less, 20 microns or less, 10 microns or less, or 5 microns or less. For example, the D of the liquid metal droplet 50 can be in the range of 1 micron to 300 microns, e.g., 5 microns to 300 microns, 150 microns to 250 microns, 5 to 150 microns, 15 microns to 150 microns, 35 microns to 150 microns, 35 microns to 70 microns, or 5 microns to 100 microns, all measured before compression. In various embodiments, the composition and / or mixing technique can be adjusted to, for example, 50 D of rigid particles in the TIM, if present, at least 1% greater, at least 2% greater, at least 5% greater, at least 10% greater, or at least 20% greater than 50 may be selected to achieve an average particle size of the liquid metal droplets greater than

[0029] As used herein, D X The D may be measured using microscopy (e.g., optical microscopy). Size may be the diameter of a spherical particle, or the length along the largest dimension in the case of an ellipsoidal or other irregularly shaped particle. As used herein, the "D" of a particle X " represents the diameter at which X% of the particle volume has a smaller diameter.

[0030] D of liquid metal droplets 90can be at least 1 micron, e.g., at least 5 microns, at least 10 microns, at least 15 microns, at least 20 microns, at least 30 microns, at least 35 microns, at least 40 microns, at least 50 microns, at least 60 microns, at least 70 microns, at least 80 microns, at least 90 microns, at least 100 microns, at least 120 microns, at least 150 microns, or at least 200 microns, all before compression. 90 can be 300 microns or less, e.g., 250 microns or less, 200 microns or less, 150 microns or less, 120 microns or less, 100 microns or less, 90 microns or less, 80 microns or less, 70 microns or less, or 50 microns or less, all before compression. For example, the D of the liquid metal droplet 90 may be in the range of 1 micron to 300 microns, for example, 5 microns to 300 microns, 150 microns to 250 microns, 10 to 200 microns, 15 microns to 150 microns, 35 microns to 150 microns, 35 microns to 120 microns, or 50 microns to 100 microns, all measured before compression.

[0031] The TIM can optionally include other components, such as at least one of rigid particles, catalysts, fumed silica, and coupling agents. The rigid particles can include at least one of iron, iron alloys (e.g., steel), vanadium, vanadium alloys, niobium, niobium alloys, titanium, titanium alloys, copper, copper alloys (e.g., bronze), aluminum, aluminum alloys, rigid polymers, glass, and ceramics. The rigid particles can be resistant to deformation and / or corrosion caused by liquid metal droplets. For example, the rigid particles can include a Young's modulus of at least 100 MPa (megapascals), such as at least 110 MPa, at least 150 MPa, at least 200 MPa, at least 250 MPa, at least 500 MPa, at least 750 MPa, at least 1 GPa (gigapascals), or at least 2 GPa. Young's modulus can be measured according to ASTM E111-17. The TIM can include 0.1% to 30% rigid particles by total volume of the TIM, such as ranges of 0.1% to 10% rigid particles, 0.1% to 5% rigid particles, 1% to 10% rigid particles, or 1% to 5% rigid particles, all based on the total volume of the TIM.

[0032] In various examples, the polymer component can include 0.1 wt % to 0.5 wt % of a coupling agent, based on the total weight of the polymer component. For example, the coupling agent can include at least one of 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-aminopropyltrimethoxysilane, and bis(3-trimethoxysilylpropyl)amine.

[0033] In one particular example, the polymer component can include 0.1% to 5% by weight of fumed silica, based on the total weight of the polymer component.

[0034] D of rigid particles in TIM 50can be selected to achieve a desired bond line thickness in the assembly. The average particle size of the rigid particles can be at least 1 micron, e.g., at least 5 microns, at least 10 microns, at least 20 microns, at least 30 microns, at least 35 microns, at least 40 microns, at least 50 microns, at least 60 microns, at least 70 microns, at least 80 microns, at least 90 microns, at least 100 microns, at least 120 microns, or at least 125 microns, etc. The D of the rigid particles 50 can be 150 microns or less, e.g., 125 microns or less, 120 microns or less, 100 microns or less, 90 microns or less, 80 microns or less, 70 microns or less, 60 microns or less, 50 microns or less, 40 microns or less, 35 microns or less, 30 microns or less, 20 microns or less, 10 microns or less, or 5 microns or less. For example, the D of the rigid particles 50 can be in the range of 1 micron to 150 microns, such as 15 to 150 microns, 5 microns to 125 microns, 35 microns to 125 microns, 35 microns to 70 microns, or 50 microns to 70 microns.

[0035] The TIM can be applied to various layers and devices and is described below with reference to Figures 1-2 with reference to a circuit assembly, but is not limited to circuit assemblies and can be applied to other assemblies. Referring to Figure 1, a method according to the present disclosure includes depositing a TIM 104 according to the present disclosure between a first layer 106 of a circuit assembly 102 and a second layer 108 of the circuit assembly 102. As illustrated, the TIM 104 includes an emulsion of liquid metal droplets 112 and a polymer 110.

[0036] As used herein, particularly in reference to layers, films, or materials, the terms "on," "onto," "over," and variations thereof (e.g., "applied on," "formed on," "deposited on," "provided on," "located on," etc.) mean applied to, formed on, deposited on, provided on, or otherwise located on, but not necessarily in contact with, the surface of a substrate. For example, a TIM "deposited on" a substrate or "deposited between" two elements does not preclude the presence of another or other layer of the same or different composition located between the applied TIM and the substrate or layer. Similarly, a second layer "deposited on" a first layer does not preclude the presence of another or other layer of the same or different composition located between the deposited second layer and the deposited TIM.

[0037] Depositing the TIM 104 can include at least one of dispensing, extrusion (e.g., through a nozzle, such as a round nozzle, a fan nozzle, or other nozzle shape), application with an implement (e.g., a brush, a spatula), stencil printing, 3D printing, and screen printing. The TIM 104 can be conformably deposited so that the TIM 104 can conform to the surfaces of the first layer 106 and the second layer 108 to achieve a desired level of surface contact therebetween. In various examples, the TIM 104 can be applied directly to the first layer 106, and then the second layer 108 can be applied directly to the TIM 104. In various other examples, the TIM 104 can be applied directly to the second layer 108, and then the first layer 106 can be applied directly to the TIM 104. In certain examples, the TIM 104 can be applied to both the first layer 106 and the second layer 108, and then the first layer 106 and the second layer 108 can be applied together. In various examples, after deposition of the TIM 104 and compression of the circuit assembly 102, the TIM 104 may be in direct contact with the first layer 106 and the second layer 108. In certain examples, application of the TIM 104 may be limited to the surface of the first layer 106 so that the TIM 104 can be used efficiently.

[0038] The TIM 104 can be dispensed from a container and applied to a conformable layer. The TIM 104 can be stored in a container prior to use. The TIM 104 can be conformable in a container. The container can include at least one of a pillow pack, a syringe, a beaker, a jar, a bottle, and a drum. In various examples, the container can be a ready-to-use dispensing device, such as a pillow pack or a syringe. In certain examples, the TIM 104 may not be stored and can be used after the emulsion is created without storage.

[0039] The TIM 104 can be applied to at least 1% of the surface area of ​​the exposed side 106a of the first layer 106, or to the entire surface area of ​​the exposed side 106a of the first layer 106, such as at least 2%, at least 5%, at least 10%, at least 20%, at least 30%, at least 40%, or at least 50%, etc., of the surface area of ​​the exposed side 106a of the first layer 106, before compressing the circuit assembly 102. For example, the TIM 104 can be applied to between 1% and 100% of the surface area of ​​the exposed side 106a of the first layer 106, or to the entire surface area of ​​the exposed side 106a of the first layer 106, such as between 2% and 100%, between 5% and 90%, or between 5% and 80%, etc., of the surface area of ​​the exposed side 106a of the first layer 106, before compressing the circuit assembly 102.

[0040] The first layer 106 may be a heat-generating electronic component (e.g., an integrated circuit such as a processor, ASIC, and / or system-on-chip (SOC)) and / or may be thermally connected to a heat-generating electronic component. The second layer 108 may be a top layer that may be thermally conductive. The first layer 106 and the second layer 108 may individually be at least one of a processor, a heat sink (e.g., fins, a fan, liquid cooling, a cooling plate), an integrated heat spreader, and packaging. In various examples, the first layer 106 may comprise a processor, and the second layer 108 may comprise at least one of a heat sink, an integrated heat spreader, and packaging. In one particular example, the first layer 106 may comprise an integrated heat spreader, and the second layer may comprise at least one of a heat sink, an integrated heat spreader, and packaging.

[0041] After deposition of the TIM 104, the method includes compressing the circuit assembly 102, thereby deforming the liquid metal droplets 112 and forming the integrated circuit 202. For example, with reference to the detailed views of FIGS. 1-2 , the first layer 106 and the second layer 108 may be biased together. For example, compressing the circuit assembly 102 may include applying a first pressure to the first layer 106 and the second layer 108, such as at least 1 psi, e.g., at least 5 psi, at least 10 psi, at least 15 psi, or at least 20 psi. In various examples, the first pressure may be in a range between 1 psi and 50 psi, e.g., between 10 and 50 psi, or between 10 and 30 psi, etc.

[0042] In various examples, the relative liquid metal surface area coverage between the TIM 104 and the first and second layers 106, 108 can increase with compression. For example, the relative liquid metal surface area coverage after compression can be in a range of 1% to 100%, e.g., 1% to 5%, 5% to 10%, 10% to 30%, 30% to 50%, etc., or can increase until the liquid metal surface area coverage reaches 100%. As used herein, "relative liquid metal surface area coverage" is the surface area covered by liquid metal normalized by the total contact surface area between the TIM 104 and the first and second layers 106, 108. The relative liquid metal surface area coverage can be measured using cross-sectioning followed by optical imaging using confocal scanning acoustic microscopy using a Hitachi FineSAT III for CSAM.

[0043] After compression, the bond line thickness t of the circuit assembly 102 Bl can be 300 microns or less, e.g., 250 microns or less, 200 microns or less, 200 microns or less, 150 microns or less, 145 microns or less, 140 microns or less, 125 microns or less, 100 microns or less, 80 microns or less, 70 microns or less, 50 microns or less, 40 microns or less, 35 microns or less, or 30 microns or less. Bl can be at least 1 micron, e.g., at least 10 microns, at least 15 microns, at least 30 microns, at least 35 microns, at least 40 microns, at least 50 microns, at least 70 microns, at least 75 microns, at least 80 microns, at least 100 microns, at least 120 microns, at least 140 microns, at least 145 microns, at least 150 microns, at least 200 microns, at least 300 microns, or at least 400 microns, etc. The bond line thickness t of the circuit assembly 102 Blmay be in the range of 1 micron to 300 microns, e.g., 1 micron to 250 microns, 10 microns to 300 microns, 10 microns to 250 microns, 1 micron to 200 microns, 15 microns to 200 microns, 15 microns to 150 microns, 30 microns to 150 microns, 50 microns to 120 microns, 75 microns to 125 microns, or 15 microns to 100 microns, etc.

[0044] D of the liquid metal droplet 112 in the TIM 104 before application 90 is the bond line thickness t Bl For example, the D of the liquid metal droplet 312 before the application and / or compression process 90 is the bond line thickness t Bl greater than, for example, the bond line thickness t Bl 1% greater than the bond line thickness t Bl 2% greater than the bond line thickness t Bl 5% greater than the bond line thickness t Bl 10% greater than the bond line thickness t Bl 15% greater than the bond line thickness t Bl 20% greater than the bond line thickness t Bl 30% greater than the bond line thickness t Bl 40% greater than the bond line thickness t Bl 50% greater than the bond line thickness t Bl The D of the liquid metal droplet 112 before the application and / or compression process may be 75% greater than 90 is the bond line thickness t Bl 100% or less than the bond line thickness t Bl 75% or less greater than the bond line thickness t Bl Bond line thickness t is no more than 50% greater than Bl Bond line thickness t is no more than 40% greater than Bl Bond line thickness t is no more than 30% greater than Bl Bond line thickness t is no more than 20% greater than Bl Bond line thickness t is no more than 15% greater than Bl Bond line thickness t is no more than 10% greater than Bl 5% or less than the bond line thickness tBl The D of the liquid metal droplet 112 before the application and / or compression process can be no more than 2% greater than the 90 is the bond line thickness t Bl 1% to 100% larger than the bond line thickness t Bl 1% to 50% larger than the bond line thickness t Bl 1% to 30% larger than the bond line thickness t Bl 2% to 30% larger than the bond line thickness t Bl It can be in the range of 5% to 20% greater than the

[0045] The TIM may cover at least 90% of the surface area of ​​the exposed side 106a of the first layer 106 after the circuit assembly is compressed, such as at least 95% of the surface area of ​​the exposed side 106a.

[0046] Compressing the circuit assembly 102 can apply a force to the TIM 104, deforming the liquid metal droplets 112 dispersed within the polymer 110 of the TIM 104. Because the polymer 110 remains conformable and mobile, the compressive force can deform the liquid metal droplets 112. The liquid metal droplets 112 can be in a liquid phase during deformation, such that less pressure is required for compression to achieve the desired deformation. For example, the liquid metal droplets 112 can be approximately spherical as shown in FIG. 1 and then approximately ellipsoidal as shown in FIG. 2. In various examples, the liquid metal droplets 112 before compression can have a first average aspect ratio, and after compression, the liquid metal droplets 112 can have a second average aspect ratio. The second average aspect ratio can be different from the first average aspect ratio. For example, the second average aspect ratio can be greater than the first average aspect ratio. The average aspect ratio can be the average ratio of the width of the liquid metal droplet 112 to the height of the liquid metal droplet 112. In various examples, the first aspect ratio can be 1 and the second aspect ratio can be greater than 1. In certain embodiments, the first aspect ratio can be in the range of 1 to 1.5. In certain embodiments, the second aspect ratio can be at least 0.5 greater than the first aspect ratio, such as at least 1 greater than the first aspect ratio, at least 2 greater than the first aspect ratio, or at least 5 greater than the first aspect ratio. In certain embodiments, the second aspect ratio can be at least 2 after compressing the circuit assembly 102, such as at least 3 or at least 4 after compressing the circuit assembly 102.

[0047] The width (e.g., longest dimension) of the liquid metal droplet 112 may be substantially aligned with the longitudinal plane of the TIM 104 in the circuit assembly 102, and the height of the liquid metal droplet 112 may be substantially aligned with the thickness (e.g., bond line thickness, t BL) The width of the liquid metal droplet 112 may increase upon compression of the circuit assembly 102. For example, in one particular example, the diameter of the liquid metal droplet before compression may be 200 μm (having a first aspect ratio of 1), and after compression to a bond line thickness of 100 μm, the liquid metal droplet may deform into an elliptical shape having a 400 μm width (e.g., a second aspect ratio of 4).

[0048] In certain instances, the liquid metal droplets 112 may be aligned in a substantially monolayer after compression, as shown in FIG. 50 and / or D. 90 , and bond line thickness t BL Arranging the liquid metal droplets 112 in a monolayer can reduce the thermal resistance of the TIM 104.

[0049] Liquid metal droplet 112 D 50 and / or D. 90 The deformation of the liquid metal droplets 112, as well as the deposition method of the liquid metal droplets 112, can improve the thermal resistance of the TIM 104. For example, the TIM 104 has a thermal resistance of at least 5°K*mm. 2 ) / W, e.g., at least 1(°K*mm 2 ) / W, at least 2(°K*mm 2 ) / W, at least 3(°K*mm 2 ) / W, at least 5(°K*mm 2 ) / W, or at least 10(°K*mm 2 ) / W. The TIM 104 has a thermal resistance of 30(°K*mm 2 ) / W or less, for example, 20(°K*mm 2 ) / W or less, 15(°K*mm 2 ) / W or less, 10(°K*mm 2 ) / W or less, 9(°K*mm 2 ) / W or less, 8(°K*mm 2 ) / W or less, 7(°K*mm 2 ) / W or less, or 5(°K*mm 2The TIM 104 may have a thermal resistance of 0.5 (°K*mm) / W or less. 2 ) / W~30(°K*mm 2 ) / W, e.g., 0.5(°K*mm 2 ) / W~20(°K*mm 2 ) / W, 0.5(°K*mm 2 ) / W~15(°K*mm 2 ) / W, 1(°K*mm 2 ) / W~10(°K*mm 2 ) / W, 2(°K*mm 2 ) / W~10(°K*mm 2 ) / W, or 2(°K*mm 2 ) / W~8(°K*mm 2 ) / W, etc. Thermal resistance values ​​can be measured using a TIMA 5 device manufactured by NanoTest (Germany).

[0050] Liquid metal droplet 112 D 50 and / or D. 90 The deformation of the liquid metal droplets 112, as well as the deposition method of the liquid metal droplets 112, can improve the thermal conductivity value of the TIM 104. For example, the TIM 104 can include an effective thermal conductivity value of at least 5 W / m*K, such as at least 10 W / m*K, at least 12 W / m*K, at least 15 W / m*K, at least 17 W / m*K, or at least 20 W / m*K. The TIM can include an effective thermal conductivity value in a range from 5 W / m*K to 50 W / m*K, such as from 10 W / m*K to 40 W / m*K, or from 10 W / m*K to 30 W / m*K. As used herein, effective thermal conductivity is the thickness of the TIM divided by the thermal resistance of the TIM.

[0051] The TIM 104 may be cured or uncured, depending on the application. For example, the TIM 104 may be cured to thicken the TIM 104, which may increase the viscosity of the polymer 110. Applying the TIM 104 at a lower viscosity may allow for more efficient placement and ability to wet the surfaces of the first layer 106 and second layer 108. Increasing the viscosity after application may allow the TIM 104 to resist pump-out and enhance removal of the TIM 104.

[0052] Curing the TIM 104 can include at least one of heating the TIM 104, adding a catalyst to the TIM 104, exposing the TIM 104 to air, applying electromagnetic radiation (e.g., photopolymerization), and applying pressure to the TIM 104. For example, a polymer component in the TIM 104 can be cured. Curing the TIM 104 can increase the viscosity of the TIM emulsion. For example, the TIM 104 can include a viscosity after curing that is at least twice the viscosity of the TIM before curing, such as at least three times, at least four times, or ten times the viscosity of the TIM before curing. For example, the TIM 104 can include a viscosity after curing of greater than 15,000 cP, such as greater than 20,000 cP, greater than 30,000 cP, greater than 50,000 cP, greater than 100,000 cP, greater than 150,000 cP, greater than 200,000 cP, greater than 250,000 cP, greater than 500,000 cP, greater than 750,000 cP, greater than 850,000 cP, greater than 1,000,000 cP, greater than 1,500,000 cP, greater than 2,500,000 cP, greater than 4,000,000 cP, or greater than 5,000,000 cP.

[0053] The circuit assembly can be used with a TIM 104, which can facilitate heat transfer between the first layer 106 and the second layer 108. The TIM 104 can be removed from at least one of the first layer 106 and / or the second layer 108. For example, the TIM 104 can be peeled off from the first layer 106 and / or the second layer 108. In various examples, the TIM 104 can be removed with a solvent, such as isopropyl alcohol. In certain examples, the TIM 104 can be removed by peeling and the use of a solvent. Removal of the TIM 104 can be more efficient due to its increased viscosity after curing.

[0054] In various other examples, a TIM according to the present disclosure can be used in a system on a package, for example, a single horizontal TIM layer can contact multiple dies on one side (e.g., an integrated circuit can include multiple dies, or multiple integrated circuits can contact the same side of the TIM) and can contact a top layer or layers on different sides.

[0055] Those skilled in the art will recognize that the compositions, articles, methods, and accompanying discussion described herein are used as examples for conceptual clarity, and that various configuration modifications are contemplated. Consequently, as used herein, the specific examples described and accompanying discussion are intended to be representative of their more general classes. In general, the use of any specific example is intended to represent that class, and the absence of specific components (e.g., acts), devices, and objects should not be considered limiting.

[0056] With respect to the appended claims, those skilled in the art will understand that the operations recited therein may generally be performed in any order. Also, while various operational flows are presented in a sequence, it should be understood that various operations may be performed in orders other than those illustrated, or may be performed simultaneously. Examples of such alternative orderings may include overlapping, interleaving, interrupting, reordering, incremental, preparing, complementary, simultaneous, reverse, or other variable orderings, unless the context dictates otherwise. Furthermore, terms such as "responsive to," "related to," or other past-tense adjectives are generally not intended to exclude such variations, unless the context dictates otherwise.

[0057] While various examples have been described herein, many modifications, variations, substitutions, changes, and equivalents to those examples may be implemented and will occur to those skilled in the art. Also, where materials are disclosed for a particular component, other materials may be used. It is therefore to be understood that the foregoing description and the appended claims are intended to cover all such modifications and variations as fall within the scope of the disclosed embodiments. The following claims are intended to cover all such modifications and variations.

[0058] Various aspects of the invention according to this disclosure include, but are not limited to, the aspects listed in the numbered clauses below.

[0059] Clause 1. A thermal interface material comprising: 5% to 30% by volume of a polymer component, based on the total volume of the thermal interface material, the polymer component comprising a polyalkylene glycol having a molecular weight in the range of 400 g / mol to 4,000 g / mol; and at least 70% by volume of liquid metal droplets, based on the total volume of the thermal interface material, the liquid metal droplets dispersed throughout the polymer component.

[0060] Clause 2. The thermal interface material of clause 1, wherein the polyalkylene glycol comprises at least one of polyethylene glycol, polypropylene glycol, polybutylene glycol, and copolymers thereof.

[0061] Clause 3. The thermal interface material of clause 1, wherein the polyalkylene glycol comprises polypropylene glycol.

[0062] Clause 4. The thermal interface material of any one of clauses 1-3, wherein the polymer component further comprises a second polymer.

[0063] Clause 5. The thermal interface material of clause 4, wherein the second polymer is miscible with the polyalkylene glycol.

[0064] Clause 6. The thermal interface material of clause 4, wherein the second polymer comprises at least one of an epoxy polymer, an acrylate polymer, a vinyl polymer, and a silicon hydride polymer.

[0065] Clause 7. The thermal interface material of clause 4, wherein the second polymer comprises an epoxy polymer comprising hydroxyl end groups.

[0066] Clause 8. The thermal interface material of clause 4, wherein the second polymer comprises a polyalkylene glycol diglycidyl ether.

[0067] Clause 9. The thermal interface material of clause 8, wherein the polymer component comprises 1 wt % to 50 wt % polyalkylene glycol, based on the total weight of the polymer component, and 50 wt % to 99 wt % polyalkylene glycol diglycidyl ether, based on the total weight of the polymer component.

[0068] Clause 10. The thermal interface material of any one of clauses 4-9, wherein the polymer component is configured to cure at a temperature of at least 50°C.

[0069] Clause 11. The thermal interface material of any one of clauses 4-10, wherein the thermal interface material comprises a first viscosity, measured at 25°C prior to curing, in the range of 1,000 cP to 850,000 cP.

[0070] Clause 12. The thermal interface material of clause 11, wherein the thermal interface material has a second viscosity after curing that is at least twice the first viscosity.

[0071] Clause 13. The thermal interface material of any one of clauses 4-12, wherein the polymer component is configured to extend polymer chains of the second polymer in response to heating to a temperature of at least 50°C.

[0072] Clause 14. The thermal interface material of any one of clauses 1-13, further comprising at least one of a catalyst and a rigid particle.

[0073] Clause 15. The thermal interface material of any one of clauses 1-14, wherein the polymer component further comprises 0.1 wt % to 0.5 wt % of a coupling agent, based on the total weight of the polymer component.

[0074] Clause 16. The thermal interface material of any one of clauses 1 to 15, wherein the polymer component further comprises 0.1 to 5 wt. % fumed silica, based on the total weight of the polymer component.

[0075] Clause 17. The thermal interface material of any one of clauses 1-16, wherein the polymer component further comprises a catalyst.

[0076] Clause 18. The thermal interface material of any one of clauses 1-17, wherein the liquid metal droplet comprises gallium, a gallium alloy, indium, an indium alloy, tin, a tin alloy, mercury, a mercury alloy, or a combination thereof.

[0077] Clause 19. The thermal interface material of any one of clauses 1-18, wherein the liquid metal droplet has a melting point of 30 degrees Celsius or less.

[0078] Clause 20. The thermal interface material of any one of clauses 1-19, wherein the polymer component further comprises a crosslinker selected from the group consisting of aminoplasts, polyisocyanates, polyepoxides, beta-hydroxyalkylamides, polyacids, anhydrides, organometallic acid-functional materials, polyamines, polyvinyls, hydrogenated polysilicones, polyalcohols, polyacid chlorides, polyhalides, and polyamides.

[0079] Clause 21. A circuit assembly comprising: a first layer; a second layer; and a thermal interface material according to any one of clauses 1 to 20 disposed in contact with and between the first layer and the second layer.

[0080] Clause 22. The circuit assembly of clause 21, wherein the liquid metal droplet is generally ellipsoidal.

[0081] Clause 23. The circuit assembly of clause 21 or 22, wherein the bond line thickness formed between the first layer and the second layer is 300 microns or less.

[0082] Clause 24. A circuit assembly described in any one of clauses 21 to 23, wherein the first layer comprises a processor and the second layer comprises at least one of a heat sink, an integrated heat spreader, a cooling plate, a fan, a liquid cooling system, and packaging.

[0083] Clause 25. A circuit assembly described in any one of clauses 21 to 24, wherein the first layer comprises an integrated heat spreader and the second layer comprises at least one of a heat sink, a cooling plate, a fan, a liquid cooling system, the integrated heat spreader, and packaging.

[0084] Clause 26. A method comprising depositing a thermal interface material according to any one of clauses 1 to 20 between a first layer of an integrated circuit assembly and a second layer of the integrated circuit assembly; and compressing the integrated circuit assembly, thereby deforming the liquid metal droplets, wherein the D of the liquid metal droplets in the thermal interface material prior to application is 90wherein the thickness of the first layer is greater than a bond line thickness formed between the first layer and the second layer.

[0085] Clause 27. The method of clause 26, further comprising curing the thermal interface material after compressing the integrated circuit assembly, thereby forming a cured assembly.

[0086] Clause 28. The method of clause 27, wherein curing comprises heating the thermal interface material to at least 50°C.

[0087] Clause 29. The method of clause 27, wherein curing includes heating the thermal interface material together with the first layer to at least 50°C.

[0088] Clause 30. The method of any one of clauses 26-29, further comprising removing the thermal interface material from at least one of the first layer and the second layer.

[0089] Clause 31. An integrated circuit assembly produced by the method of any one of clauses 26 to 30.

[0090] Clause 32. A thermal interface material comprising: 5% to 30% by volume of a polymer component, based on the total volume of the thermal interface material, the polymer component having a first polymer having a molecular weight in the range of 400 g / mol to 400,000 g / mol; and a second polymer component, the second polymer configured to undergo chain extension in response to heating to a temperature of at least 50°C; and at least 70% by volume of liquid metal droplets, based on the total volume of the thermal interface material, dispersed throughout the polymer component.

[0091] Clause 33. The thermal interface material of clause 32, wherein the second polymer is miscible with the first polymer.

[0092] Clause 34. The thermal interface material of clause 32 or 33, wherein the second polymer comprises an epoxy polymer, an acrylate polymer, a vinyl polymer, and a silicon hydride polymer.

[0093] Clause 35. The thermal interface material of any one of clauses 32-34, wherein the first polymer comprises at least one of a polymeric binder, a thermosetting polymer, and a thermoplastic polymer.

[0094] Clause 36. The thermal interface material of any one of clauses 32-35, wherein the first polymer comprises at least one of an acrylic polymer, an acrylate polymer, a vinyl polymer, a polyester polymer, a polyurethane polymer, a polybutadiene, a polyamide polymer, a polyether polymer, a polysiloxane polymer, a silicon hydride polymer, a fluoropolymer, a polyisoprene polymer, and copolymers thereof.

[0095] Clause 37. The thermal interface material of any one of clauses 32-36, wherein the polymer component comprises 1 wt% to 50 wt% of the first polymer, based on the total weight of the polymer component, and 50 wt% to 99 wt% of the second polymer, based on the total weight of the polymer component.

[0096] Clause 38. The thermal interface material of any one of clauses 32-37, wherein the polymer component is configured to cure at a temperature of at least 50°C.

[0097] Clause 39. The thermal interface material of any one of clauses 32-38, wherein the thermal interface material comprises a first viscosity, measured at 25°C prior to curing, in the range of 1,000 cP to 850,000 cP.

[0098] Clause 40. The thermal interface material of clause 39, wherein the thermal interface material has a second viscosity after curing that is at least twice the first viscosity.

[0099] Clause 41. The thermal interface material of any one of clauses 32-40, wherein the polymer component is configured to extend the polymer chains of the second polymer in response to heating to a temperature of at least 50°C.

[0100] Clause 42. The thermal interface material of any one of clauses 32-41, wherein the polymer component further comprises a crosslinker selected from the group consisting of aminoplasts, polyisocyanates, polyepoxides, beta-hydroxyalkylamides, polyacids, anhydrides, organometallic acid-functional materials, polyamines, polyvinyls, hydrogenated polysilicones, polyalcohols, polyacid chlorides, polyhalides, and polyamides.

[0101] Clause 43. A circuit assembly comprising a first layer, a second layer, and a thermal interface material according to any one of clauses 32 to 42 in contact with and disposed between the first layer and the second layer.

[0102] Clause 44. A method comprising depositing a thermal interface material according to any one of clauses 32 to 42 between a first layer of an integrated circuit assembly and a second layer of the integrated circuit assembly; and compressing the integrated circuit assembly, thereby deforming the liquid metal droplets, wherein the D of the liquid metal droplets in the thermal interface material prior to application is 90 wherein the thickness of the first layer is greater than a bond line thickness formed between the first layer and the second layer.

[0103] As used herein, "at least one of" a list of elements means one of the elements or any combination of two or more of the listed elements. By way of example, "at least one of A, B, and C" means A only, B only, C only, A and B, A and C, B and C, or A, B, and C.

[0104] Various features and characteristics are described herein to provide an understanding of the composition, structure, manufacture, function, and / or operation of the invention, including the disclosed compositions, coatings, and methods. It should be understood that the various features and characteristics of the invention described herein may be combined in any suitable manner, regardless of whether such features and characteristics are expressly described in combination herein. The inventors and applicants expressly intend that such combinations of features and characteristics be included within the scope of the inventions described herein. Thus, the claims may be amended to recite any features and characteristics explicitly or inherently described or otherwise explicitly or inherently supported by the specification, in any combination. Furthermore, applicants reserve the right to amend the claims to affirmatively reject features and characteristics that may exist in the prior art, even if those features and characteristics are not explicitly described herein. Accordingly, any such amendments will not add new matter to the specification or claims, but will comply with the requirements of written description, sufficiency of description, and added matter.

[0105] Any numerical range recited herein describes all subranges of the same numerical precision (i.e., having the same number of specified digits) contained within the recited range. For example, a recited range of "1.0 to 10.0" describes all subranges from the recited minimum value of 1.0 to the recited maximum value of 10.0 (including their upper and lower limits), such as "2.4 to 7.6," even if a range of "2.4 to 7.6" is not explicitly recited within the text of this specification. Accordingly, applicants reserve the right to amend this specification, including the claims, to explicitly recite any subrange of the same numerical precision contained within a range explicitly recited herein. All such ranges are inherently described herein, and therefore any amendment to explicitly recite any such subrange will comply with the requirements of written description, sufficiency of description, and added matter.

[0106] Additionally, unless expressly specified otherwise or required otherwise by context, all numerical parameters set forth herein (such as those representing values, ranges, amounts, percentages, etc.) may be read as if preceded by the word "about," even if the word "about" does not explicitly appear before the numerical value. In addition, numerical parameters set forth herein should be construed in light of the reported number of significant digits, numerical precision, and the application of ordinary rounding techniques. It is also understood that the numerical parameters set forth herein necessarily reflect the inherent variability characteristic of the underlying measurement techniques used to determine the numerical value of the parameters.

[0107] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values ​​set forth in the specific examples are reported as precisely as possible. However, any numerical value inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements.

[0108] References throughout this specification to "various examples," "some examples," "one example," "an example," or the like mean that a particular feature, structure, or characteristic described in connection with the example is included in the example. Thus, the appearances of phrases such as "various examples," "some examples," "in one example," or "in an example" in various locations throughout this specification do not necessarily all refer to the same example. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more examples. Thus, a particular feature, structure, or characteristic illustrated or described in connection with one example may be combined, in whole or in part, with a feature, structure, or characteristic of another example or other examples, without limitation. Such modifications and variations are intended to be included within the scope of the present embodiments.

[0109] Any patent, publication, or other document identified herein is incorporated herein by reference in its entirety, unless otherwise indicated, to the extent that the incorporated material does not conflict with existing explanations, definitions, descriptions, illustrations, or other disclosure material expressly set forth herein. Accordingly, to the extent necessary, the explicit disclosure set forth herein supersedes any conflicting material incorporated by reference. Any material, or portion thereof, incorporated herein by reference that conflicts with an existing definition, description, or other disclosure material set forth herein is incorporated only to the extent that a conflict arises between the incorporated material and the existing disclosure material. Applicant reserves the right to amend this specification to explicitly recite any subject matter, or portion thereof, incorporated by reference. Amendments to this specification to add such incorporated subject matter will comply with the requirements of written description, sufficiency of description, and the added subject matter.

[0110] Although particular examples of the present invention have been described above for purposes of illustration, it will be apparent to those skilled in the art that many variations in the details of the invention can be made without departing from the invention as defined in the appended claims.

[0111] While this disclosure provides descriptions of various specific embodiments for the purpose of illustrating various aspects of the disclosure and / or its potential applications, it should be understood that variations and modifications will occur to those skilled in the art. Accordingly, the invention or inventions described herein should be understood to be at least as broad as they are claimed, and not more narrowly defined by the specific illustrative embodiments provided herein.

[0112] It is to be understood that the invention described herein is not limited to the examples summarized in the Summary or Detailed Description. Various other aspects are described and illustrated herein.

Claims

1. 1. A thermal interface material comprising: 5% to 30% by volume of a polymer component, based on the total volume of the thermal interface material, the polymer component comprising a polyalkylene glycol having a molecular weight in the range of 400 g / mol to 4,000 g / mol; at least 70% by volume of liquid metal droplets, based on a total volume of the thermal interface material, dispersed throughout the polymer component.

2. 10. The thermal interface material of claim 1, wherein the polyalkylene glycol comprises at least one of polyethylene glycol, polypropylene glycol, polybutylene glycol, and copolymers thereof.

3. 10. The thermal interface material of claim 1, wherein the polyalkylene glycol comprises polypropylene glycol.

4. The thermal interface material of claim 1 , wherein the polymer component further comprises a second polymer.

5. The thermal interface material of claim 4 , wherein the second polymer is miscible with the polyalkylene glycol.

6. The thermal interface material of claim 4 , wherein the second polymer comprises at least one of an epoxy polymer, an acrylate polymer, a vinyl polymer, and a silicon hydride polymer.

7. The thermal interface material of claim 4 , wherein the second polymer comprises an epoxy polymer containing hydroxyl end groups.

8. The thermal interface material of claim 4 , wherein the second polymer comprises a polyalkylene glycol diglycidyl ether.

9. The polymer component is 1 wt % to 50 wt % of the polyalkylene glycol, based on the total weight of the polymer component; 9. The thermal interface material of claim 8, comprising 50% to 99% by weight of the polyalkylene glycol diglycidyl ether, based on the total weight of the polymer component.

10. The thermal interface material of claim 4 , wherein the polymer component is configured to cure at a temperature of at least 50° C.

11. 5. The thermal interface material of claim 4, wherein the thermal interface material comprises a first viscosity measured at 25°C before curing in the range of 1,000 cP to 850,000 cP.

12. 12. The thermal interface material of claim 11, wherein the thermal interface material has a second viscosity after curing that is at least twice the first viscosity.

13. 5. The thermal interface material of claim 4, wherein the polymer component is configured to extend the polymer chains of the second polymer in response to heating to a temperature of at least 50°C.

14. The thermal interface material of claim 1 , further comprising at least one of a catalyst and rigid particles.

15. 10. The thermal interface material of claim 1, wherein the polymer component further comprises 0.1% to 0.5% by weight of a coupling agent, based on the total weight of the polymer component.

16. 10. The thermal interface material of claim 1, wherein the polymer component further comprises 0.1 to 5 weight percent fumed silica, based on the total weight of the polymer component.

17. The thermal interface material of claim 1 , wherein the polymer component further comprises a catalyst.

18. The thermal interface material of claim 1 , wherein the liquid metal droplet comprises gallium, a gallium alloy, indium, an indium alloy, tin, a tin alloy, mercury, a mercury alloy, or a combination thereof.

19. The thermal interface material of claim 1 , wherein the liquid metal droplet comprises a melting point of 30 degrees Celsius or less.

20. 10. The thermal interface material of claim 1, wherein the polymer component further comprises a crosslinker selected from the group consisting of aminoplasts, polyisocyanates, polyepoxides, beta-hydroxyalkylamides, polyacids, anhydrides, organometallic acid-functional materials, polyamines, polyvinyls, hydrogenated polysilicon, polyalcohols, polyacid chlorides, polyhalides, and polyamides.

21. 1. A circuit assembly comprising: a first layer; and a second layer; and and the thermal interface material of claim 1 disposed in contact with and between the first layer and the second layer.

22. 22. The circuit assembly of claim 21, wherein the liquid metal droplet is generally ellipsoidal.

23. 22. The circuit assembly of claim 21, wherein a bond line thickness formed between the first layer and the second layer is 300 microns or less.

24. 22. The circuit assembly of claim 21, wherein the first layer comprises a processor and the second layer comprises at least one of a heat sink, an integrated heat spreader, a cooling plate, a fan, a liquid cooling system, and packaging.

25. 22. The circuit assembly of claim 21, wherein the first layer comprises an integrated heat spreader and the second layer comprises at least one of a heat sink, a cooling plate, a fan, a liquid cooling system, an integrated heat spreader, and packaging.

26. 1. A method comprising: depositing the thermal interface material of claim 1 between a first layer of an integrated circuit assembly and a second layer of said integrated circuit assembly; compressing the integrated circuit assembly, thereby deforming the liquid metal droplet; and ９０ is greater than a bond line thickness formed between the first layer and the second layer.

27. 27. The method of claim 26, further comprising curing the thermal interface material after compressing the integrated circuit assembly, thereby forming a cured assembly.

28. 28. The method of claim 27, wherein the curing comprises heating the thermal interface material to at least 50°C.

29. 28. The method of claim 27, wherein said curing comprises heating the thermal interface material together with the first layer to at least 50°C.

30. 30. The method of claim 27, further comprising removing the thermal interface material from at least one of the first layer and the second layer.

31. 27. An integrated circuit assembly produced by the method of claim 26.

32. 1. A thermal interface material comprising: a polymer component of 5% to 30% by volume, based on the total volume of the thermal interface material, the polymer component comprising: a first polymer having a molecular weight in the range of 400 g / mol to 400,000 g / mol; and a second polymer component, the second polymer configured to undergo chain extension in response to heating to a temperature of at least 50°C; at least 70% by volume of liquid metal droplets, based on a total volume of the thermal interface material, dispersed throughout the polymer component.

33. 33. The thermal interface material of claim 32, wherein the second polymer is miscible with the first polymer.

34. 33. The thermal interface material of claim 32, wherein the second polymer comprises an epoxy polymer, an acrylate polymer, a vinyl polymer, and a silicon hydride polymer.

35. 33. The thermal interface material of claim 32, wherein the first polymer comprises at least one of a polymeric binder, a thermosetting polymer, and a thermoplastic polymer.

36. 33. The thermal interface material of claim 32, wherein the first polymer comprises at least one of an acrylic polymer, an acrylate polymer, a vinyl polymer, a polyester polymer, a polyurethane polymer, a polybutadiene, a polyamide polymer, a polyether polymer, a polysiloxane polymer, a silicon hydride polymer, a fluoropolymer, a polyisoprene polymer, and copolymers thereof.

37. The polymer component is 1 wt % to 50 wt % of the first polymer, based on the total weight of the polymer component; and 50% to 99% by weight of the second polymer, based on the total weight of the polymer component.

38. 33. The thermal interface material of claim 32, wherein the polymer component is configured to cure at a temperature of at least 50°C.

39. 33. The thermal interface material of claim 32, wherein the thermal interface material comprises a first viscosity measured at 25°C before curing in the range of 1,000 cP to 850,000 cP.

40. 40. The thermal interface material of claim 39, wherein the thermal interface material has a second viscosity after curing that is at least twice the first viscosity.

41. 33. The thermal interface material of claim 32, wherein the polymer component is configured to extend the polymer chains of the second polymer in response to heating to a temperature of at least 50°C.

42. 33. The thermal interface material of claim 32, wherein the polymer component further comprises a crosslinker selected from the group consisting of aminoplasts, polyisocyanates, polyepoxides, beta-hydroxyalkylamides, polyacids, anhydrides, organometallic acid-functional materials, polyamines, polyvinyls, hydrogenated polysilicon, polyalcohols, polyacid chlorides, polyhalides, and polyamides.

43. 1. A circuit assembly comprising: a first layer; and a second layer; and and the thermal interface material of claim 32 disposed in contact with and between the first layer and the second layer.

44. 1. A method comprising: depositing the thermal interface material of claim 32 between a first layer of an integrated circuit assembly and a second layer of said integrated circuit assembly; compressing the integrated circuit assembly, thereby deforming the liquid metal droplet; and ９０ is greater than a bond line thickness formed between the first layer and the second layer.

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