Method, apparatus, and assembly for thermally connecting a thermal interface material containing rigid particles to a layer.

Abstract

The die of the circuit assembly and the top layer of the circuit assembly are thermally connected by applying a thermal interface material (TIM) onto the die, such that the TIM is between the die and the top layer. The TIM includes an emulsion of liquid metal droplets, rigid particles, and an uncured polymer. The method further includes compressing the circuit assembly, thereby deforming the liquid metal droplets, and forming a bond line distance between the die and the top layer that is 90%-110% of the average diameter of the rigid particles. The average diameter of the liquid metal droplets in the thermal interface material prior to application is greater than the average diameter of the rigid particles. The thermal interface material is cured, thereby forming the circuit assembly.

Description

[Technical Field]

[0001] This disclosure relates to a method, apparatus, and assembly for thermally connecting two layers with a thermal interface material containing rigid particles. [Background technology]

[0002] 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 die to the integrated heat spreader (IHS) of the CPU package. Various types of TIMs exist and can be used. However, current TIMs present challenges. [Overview of the Initiative]

[0003] In general embodiments, the present invention relates to a method for thermally connecting a die and an upper layer. The method comprises applying a thermal interface material onto the die of a circuit assembly, so that the thermal interface material is between the die and the upper layer of the circuit assembly. In various examples, the circuit assembly may be a processor, an ASIC, or a system-on-a-chip (SOC). In certain examples, the upper layer may be an integrated heat spreader, a heat sink, or a package. The thermal interface material applied to the die comprises an emulsion of liquid metal droplets, rigid particles, and an uncured polymer. The liquid metal droplets are in the liquid phase at temperatures in the range of at least -20°C to 30°C. The method comprises compressing the circuit assembly, thereby deforming the liquid metal droplets, and forming a bond line distance between the die and the upper layer, which is 95% to 125% of the average particle size of the rigid particles. The average particle size of the liquid metal droplets in the thermal interface material before application is greater than the average particle size of the rigid particles. The method further comprises curing the thermal interface material, thereby forming the circuit assembly.

[0004] In another general embodiment, the present invention relates to a circuit assembly comprising a die, an upper layer, and a thermal interface material disposed in contact with the die layer and the upper layer. The thermal interface material comprises a polymer, liquid metal droplets, and rigid particles dispersed throughout the polymer. The bond line distance formed between the die and the upper layer is 95% to 125% of the average particle size of the rigid particles. The liquid metal droplets have a first aspect ratio, and the rigid spheres have a second aspect ratio, with the first aspect ratio being greater than the second aspect ratio. The liquid metal droplets are in the liquid phase at temperatures in the range of at least -20°C to 30°C.

[0005] In another general embodiment, the present invention relates to an apparatus for thermally connecting a die and an upper layer, the apparatus comprising a container defining a cavity and an emulsion disposed within the cavity. The emulsion comprises liquid metal droplets, rigid particles, and an uncured polymer, and the container is configured to allow application of the emulsion onto the die of the circuit assembly. The average particle size of the liquid metal droplets is greater than the average particle size of the rigid particles. The liquid metal droplets are in the liquid phase at temperatures in the range of at least -20°C to 30°C.

[0006] In another general embodiment, the present invention relates to a method for thermally connecting two or more layers. The method comprises applying a thermal interface material onto a first layer such that the thermal interface material is located between a first layer and a second layer of an assembly. The thermal interface material comprises an emulsion of liquid metal droplets, rigid particles, and an uncured polymer. The liquid metal droplets are in the liquid phase at temperatures in the range of at least -20°C to 30°C. The method comprises compressing the assembly, thereby deforming the liquid metal droplets, and forming a bond line distance between the die and the upper layer, which is 95% to 125% of the average particle size of the rigid particles. The average particle size of the liquid metal droplets in the thermal interface material before application is greater than the average particle size of the rigid particles. The method further comprises curing the thermal interface material, thereby forming the assembly.

[0007] The present invention can provide both low contact resistance at the material interface and low thermal resistance through the material. Low contact resistance can be achieved by applying an uncured polymer so that the polymer and liquid metal droplets can conform to the surface of the layer and achieve the desired contact resistance. Low thermal resistance through the material can be achieved by the liquid metal droplets, including the size and / or shape of the liquid metal droplets and / or the size of the rigid particles. In addition, the method described herein may not require high pressure for installation compared to the method resulting from the application of an uncured polymer, and the method described herein can be installed at room temperature (e.g., 23°C ± 3°C) due to the application of an uncured polymer and the fact that the liquid metal droplets are in the liquid phase at room temperature. Furthermore, curing the polymer can suppress pumping from the liquid metal droplets. In addition, rigid particles can enable effective control of the bond line distance, and applying rigid particles before the application of the polymer and liquid metal droplet emulsion can enable effective control of the bond line distance. These and other advantages achievable from various embodiments of the present invention will be evident from the following description. [Brief explanation of the drawing]

[0008] The features and advantages of various embodiments of the present invention, as well as the ways in which they are achieved, will become clearer, and the embodiments will be better understood by referring to the following description of the embodiments illustrated in conjunction with the accompanying drawings.

[0009] [Figure 1] This is a schematic diagram of a container containing a TIM emulsion according to this disclosure.

[0010] [Figure 2A] This is a side cross-sectional view of a circuit assembly including a TIM according to this disclosure.

[0011] [Figure 2B] This is a side cross-sectional view of a circuit assembly including a TIM according to this disclosure.

[0012] [Figure 3A] This is a detailed view of region 3A of the circuit assembly in Figure 2 before the circuit assembly was compressed.

[0013] [Figure 3B] This is the circuit assembly shown in Figure 3A after circuit assembly compression.

[0014] [Figure 4A] This is an image of the hardened formulation of Example 1 after compression.

[0015] [Figure 4B] This is an image of the hardened Example Formulation 2 after compression.

[0016] Corresponding reference letters indicate corresponding parts across several figures. The examples described herein illustrate a particular embodiment in one form, and such examples should not be construed as limiting the scope of the embodiment in any way. [Modes for carrying out the invention]

[0017] Certain exemplary embodiments of the present invention are described herein to provide an overall understanding of the principles and methods of the compositions, functions, manufactures, and uses 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 the various embodiments of the present invention is defined solely by the claims. Features illustrated or described in relation to one exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are intended to fall within the scope of the present invention.

[0018] Applying a material to a die in a circuit assembly, such as when the material lies between the die and the integrated heat spreader (IHS), may require balancing the thermal resistance through the material with the contact resistance at the material interface. For example, polymer materials may have low contact resistance at the material interface but high thermal resistance through the material. Solid metals may have low thermal resistance through the material but high contact resistance at the material interface. In addition, some solid materials (polymers or metals) may require high pressure during installation to achieve the desired contact resistance. Furthermore, when using thermal interface materials with liquid metal droplets, there are challenges in achieving the desired bond line distance between the die and the IHS.

[0019] Therefore, the present invention provides thermal interface materials (TIMs), assemblies for thermally connecting two layers, and circuit assemblies that, in various embodiments, can provide both low contact resistance at the material interface and low thermal resistance through the material while achieving a desired bond line thickness. In addition, TIMs may not require high pressure for installation compared to other solid materials. For example, a TIM may require a pressure of 50 pounds per square inch or less for installation (e.g., compression). TIMs according to this disclosure may include polymers, liquid metal droplets, and rigid particles. Liquid metal droplets may be dispersed throughout the polymer, and / or rigid particles may be dispersed throughout the polymer.

[0020] As used herein, the terms “polymer” and “polymeric” mean both prepolymers, oligomers, and homopolymers and copolymers. As used herein, “prepolymer” means a polymer precursor that is capable of further reaction or polymerization with one or more reactive groups to form a higher molecular weight or crosslinked state.

[0021] The polymer may be a thermosetting polymer, a thermoplastic polymer, or a combination thereof. As used herein, the term “thermosetting” refers to a polymer that “cures” irreversibly upon curing or crosslinking, where the polymer chains of the polymer component are joined together by covalent bonds, which are often induced, for example, by heat or radiation. In various examples, the curing or crosslinking reaction may be carried out under ambient conditions. Once cured or crosslinked, a thermosetting polymer may not melt upon application of heat and may be insoluble in conventional solvents. As used herein, the term “thermoplastic” refers to a polymer containing polymer components whose constituent polymer chains are not covalently bonded (e.g., crosslinked), thereby allowing them to receive a liquid flow upon heating and being soluble in conventional solvents. In certain embodiments, the polymer may be an elastomer (e.g., rubbery, soft, stretchable) or a rigid (e.g., glassy). For example, the polymer may be an elastomer.

[0022] Thermosetting polymers may contain crosslinking agents, such as aminoplasts, polyisocyanates (including blocked isocyanates), polyepoxides, beta-hydroxyalkylamides, polyacids, anhydrides, organometallic acid functional materials, polyamines, polyamides, or combinations thereof. The polymer may have functional groups that react with the crosslinking agent.

[0023] The polymers in the TIM described herein may be selected from any of the various polymers known in the art. For example, thermosetting polymers may include acrylic polymers, polyester polymers, polyurethane polymers, polyamide polymers, polyether polymers, polysiloxane polymers (e.g., poly(dimethylsiloxone)), fluoropolymers, polyisoprene polymers (e.g., rubber), copolymers thereof (e.g., styreneethylenebutylenestyrene), or combinations thereof. Functional groups on the thermosetting polymers may be selected from any of the various reactive functional groups, including, for example, carboxylic acid groups, amine groups, epoxide groups, hydroxyl groups, thiol groups, carbamate groups, amide groups, urea groups, isocyanate groups (including blocked isocyanate groups), mercaptan groups, and combinations thereof.

[0024] Thermoplastic polymers may include propylene-ethylene copolymers, styrene-butadiene-styrene, styreneethylenebutylenestyrene, or combinations thereof. The polymers may have 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.

[0025] Liquid metals for TIM may include gallium, gallium alloys, indium, indium alloys, tin, tin alloys, mercury, mercury alloys, or combinations thereof. The liquid metal may be in the liquid phase at a minimum temperature of at least -20 degrees Celsius (for example, its bulk form may include a melting point below -20 degrees Celsius), such as 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 may be in the liquid phase at a minimum temperature of at least 30 degrees Celsius, such as at least 25 degrees Celsius, at least 20 degrees Celsius, at least 15 degrees Celsius, at least 10 degrees Celsius, at least 5 degrees Celsius, at least 0 degrees Celsius, or at least -10 degrees Celsius (for example, its bulk form may include a melting point below 30 degrees Celsius). Liquid metals can be in the liquid phase at temperatures within the range of at least -20°C to 30°C, such as -19°C to 30°C, -19°C to 25°C, or -19°C to 20°C (for example, in their bulk form, they may have a melting point below a temperature within the range of -20°C to 30°C). The determination of whether the liquid phase is achieved at each temperature can be made using an absolute pressure of 1 atmosphere. In certain embodiments, the TIM may include gallium indium tin (e.g., Galinstan) with a melting point of -19°C.

[0026] The rigid particles may include iron, iron alloys (e.g., steel, stainless steel), vanadium, vanadium alloys, niobium, niobium alloys, titanium, titanium alloys, copper, copper alloys (e.g., bronze), rigid polymers, glass, ceramics, or combinations thereof. The rigid particles may be resistant to deformation and / or corrosion by liquid metal droplets. For example, the rigid particles may have 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. The Young's modulus can be measured according to ASTM E111-17.

[0027] TIM can be prepared by forming an emulsion of polymer, liquid metal, and rigid particles, so that the liquid metal droplets and rigid particles are substantially dispersed throughout the polymer. For example, the polymer, liquid metal droplets, and rigid particles can be mixed with a high-shear mixer or centrifugal mixer by shaking in a container, mortar and pestle, sonication, or a combination thereof. Details of exemplary methods for forming the emulsion are described in (1) the published PCT WO / 2019 / 136252, titled “Method of Synthesizing a Thermally Conductive and Stretchable Polymer Composite”, (2) the published U.S. Patent Application No. 2017 / 0218167, titled “Polymer Composite with Liquid Phase Metal Inclusions”, and (3) U.S. Patent No. 10,777,483, titled “Method, apparatus, and assembly for thermally connecting layers”, all of which are incorporated herein by reference in their entirety. In various embodiments, TIM can be created by forming a layer of rigid particles and then applying an emulsion of polymer and liquid metal to the layer of rigid particles.

[0028] The composition and / or mixing technique can be selected so that the viscosity of the uncured TIM emulsion is less than 850,000 cp (centipoise), such as 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. The viscosity of the TIM emulsion can be measured at room temperature by a rotational viscometer or a cone and plate viscometer. Viscosity measurements can be performed at a selected frequency suitable for generating static viscosity (for example, because the material is a non-Newtonian fluid).

[0029] TIM may contain at least 7 volume% of polymer based on the total volume of TIM, for example, at least 10 volume%, at least 15 volume%, at least 20 volume%, at least 25 volume%, at least 30 volume%, at least 35 volume%, at least 40 volume%, at least 45 volume%, or at least 50 volume%. TIM may contain 70 volume% or less of polymer based on the total volume of TIM, for example, 65 volume% or less, 60 volume% or less, 55 volume% or less, 50 volume% or less, 45 volume% or less, or 40 volume% or less. TIM may contain polymer in the range of 7 volume% to 70 volume% based on the total volume of TIM, for example, 20 volume% to 50 volume%, 30 volume% to 50 volume%, 30 volume% to 60 volume%, 40 volume% to 60 volume%, or 40 volume% to 70 volume%.

[0030] TIM can contain at least 1 volume% of liquid metal droplets based on the total volume of the TIM, such as at least 5 volume% of liquid metal droplets, at least 10 volume% of liquid metal droplets, at least 20 volume% of liquid metal droplets, at least 30 volume% of liquid metal droplets, at least 40 volume% of liquid metal droplets, at least 50 volume% of liquid metal droplets, or at least 60 volume% of liquid metal droplets. TIM can contain 92 volume% or less of liquid metal droplets based on the total volume of the TIM, such as 90 volume% or less of liquid metal droplets, 80 volume% or less of liquid metal droplets, 70 volume% or less of liquid metal droplets, 60 volume% or less of liquid metal droplets, 50 volume% or less of liquid metal droplets, 40 volume% or less of liquid metal droplets, 30 volume% or less of liquid metal droplets, 20 volume% or less of liquid metal droplets, or 10 volume% or less of liquid metal droplets. TIMs can contain liquid metal droplets ranging from 1% to 92% based on the total volume of the TIM, for example, 1% to 90% liquid metal droplets, 5% to 50% liquid metal droplets, 40% to 60% liquid metal droplets, 5% to 90% liquid metal droplets, or 30% to 50% liquid metal droplets. The amount of liquid metal droplets can affect the morphology of the TIM and its thermal conductivity.

[0031] TIM can contain at least 0.1 volume% rigid particles based on the total volume of the TIM, such as at least 1 volume% rigid particles, at least 5 volume% rigid particles, at least 10 volume% rigid particles, or at least 20 volume% rigid particles, all based on the total volume of the TIM. TIM can contain up to 30 volume% rigid particles based on the total volume of the TIM, such as 25 volume% or less rigid particles, 20 volume% or less rigid particles, 10 volume% or less rigid particles, 5 volume% or less rigid particles, or 1 volume% or less rigid particles, all based on the total volume of the TIM. TIM can contain a range of rigid particles from 0.1 volume% to 30 volume% based on the total volume of the TIM, such as 0.1 volume% to 10 volume% rigid particles, 0.1 volume% to 5 volume% rigid particles, 1 volume% to 10 volume% rigid particles, or 1 volume% to 5 volume% rigid particles, all based on the total volume of the TIM. The amount of rigid particles can affect the control of the morphology of the TIM, the thermal conductivity of the TIM, and the thickness of the TIM's bonding lines. For example, insufficient rigid particles may lead to a lack of control over the thickness of the TIM's bonding lines, while too many rigid particles may lead to undesirable changes in the morphology and / or thermal conductivity of the TIM.

[0032] Compositions and / or mixing techniques may be selected to achieve a desired average particle size of liquid metal droplets in the TIM. The average particle size of the liquid metal droplets may be at least 1 micron, for example, 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 150 microns. The average particle size of the liquid metal droplets may be 200 microns or less, for example, 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 average particle size of the liquid metal droplets can be in the range of 1 to 200 microns, such as 5 to 150 microns, 15 to 150 microns, 35 to 150 microns, 35 to 70 microns, or 5 to 100 microns. In various embodiments, the composition and / or mixing technique may be selected to achieve an average particle size of liquid metal droplets that is larger than the average particle size of the rigid particles in the TIM, for example, by at least 1%, at least 2%, at least 5%, at least 10%, or at least 20%.

[0033] As used herein, "average particle size" means the average size (i.e., D) measured using a microscopy method (e.g., optical microscopy or electron microscopy). 50 ) represents the diameter of a spherical particle, or, in the case of an ellipsoidal or other irregularly shaped particle, the length along the maximum dimension. When used herein, the "D" of a particle is used to represent the diameter of a spherical particle. 10 " represents the diameter in which 10% of the particle's volume has a smaller diameter. When used herein, "D" refers to the diameter of a particle. 90 " represents the diameter where 90% of the volume of particles in the powder has a smaller diameter.

[0034] The polydispersibility of liquid metal droplets can be unimodal or multimodal (e.g., bimodal, trimodal). Multimodal polydispersibility can be utilized to increase the packing density of liquid metal droplets in TIM. In certain embodiments where the polydispersibility is unimodal, the polydispersibility of liquid metal droplets in the polymer can be in the range of 0.3 to 0.4.

[0035] The average particle size of the rigid particles in the TIM can be selected to achieve a desired bond line distance in the assembly. The average particle size of the rigid particles can be at least 1 micron, for example, 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. The average particle size of the rigid particles can be 150 microns or less, for example, 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 average diameter of rigid particles can be in the range of 1 to 150 microns, such as 15 to 150 microns, 5 to 125 microns, 35 to 125 microns, 35 to 70 microns, or 50 to 70 microns.

[0036] TIM can be stored in a container 100 before use, as illustrated in Figure 1. For example, the container may have walls 102 defining a cavity, and the TIM emulsion 104 can be stored in the cavity. The TIM 104 may remain in an uncured state within the container 100. Storing the TIM 104 in the container 100 can suppress the curing of the TIM 104. The container 100 may be a pillow pack, syringe, beaker, bottle, drum, or a combination thereof. In various examples, the container 100 may be a readily usable dispensing device, such as a pillow pack or syringe. In other examples, the TIM 104 may not be stored and may be used after the emulsion is formed without storage.

[0037] As used herein, the terms “cure” and “curing” refer to the chemical crosslinking of components in an emulsion or material applied to a substrate, or to an increase in the viscosity of components in an emulsion or material applied to a substrate. Therefore, the terms “cure” and “curing” do not encompass only the physical drying of the emulsion or material through solvent or carrier evaporation. In this regard, as used herein in examples involving thermosetting polymers, the term “cured” refers to the state of an emulsion or material in which components 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 curing agent). As used herein in examples involving thermoplastic polymers, the term “cured” refers to the state of an emulsion or material in which the temperature of the thermoplastic polymer has decreased below its melting point, resulting in an increase in the viscosity of the emulsion or material. In examples involving both thermosetting and thermoplastic polymers, the term “cured” refers to one or both polymers curing as described herein.

[0038] Curing of a thermosetting polymer can be achieved by applying a temperature of at least -20 degrees Celsius to the TIM 104, for example, at least 10 degrees Celsius, at least 50 degrees Celsius, at least 100 degrees Celsius, or at least 150 degrees Celsius. Curing can be achieved by applying a temperature of 300 degrees Celsius or less to the TIM 104, for example, at least 250 degrees Celsius, at least 200 degrees Celsius, at least 150 degrees Celsius, at least 100 degrees Celsius, or at least 50 degrees Celsius. Curing can be achieved by applying a temperature of -20 degrees Celsius to 300 degrees Celsius to the TIM 104, for example, at a range of 10 degrees Celsius to 200 degrees Celsius, or at least 50 degrees Celsius to 150 degrees Celsius. For example, curing may include heat firing the TIM. The temperature can be applied for a period of time exceeding 1 minute, for example, exceeding 5 minutes, exceeding 30 minutes, exceeding 1 hour, or exceeding 2 hours.

[0039] TIM104 can be dispensed from container 100 and applied to an uncured layer. In various examples, TIM104 does not contain rigid particles in container 100, the rigid particles are applied as a particle layer, and TIM104 without rigid particles is applied on top of the particle layer. The TIM104 can then be cured to form a cured TIM104. Curing TIM104 can include heating TIM104 (e.g., in the example with a thermosetting polymer), adding a catalyst to TIM104, exposing TIM104 to air, cooling TIM104 (e.g., in the example with a thermoplastic polymer), applying pressure to TIM104, or a combination thereof. Curing TIM104 can increase the viscosity of the TIM emulsion to over 15,000 cP, for example, over 20,000 cP, over 30,000 cP, over 50,000 cP, over 100,000 cP, over 150,000 cP, over 200,000 cP, over 250,000 cP, over 500,000 cP, over 750,000 cP, or over 850,000 cP. For example, polymers in TIM104 can be cured. In various examples, TIM104 can be an adhesive. Polymers in TIM104 may be selected to reduce gas release of TIM104 during curing.

[0040] The TIM according to this disclosure can be applied to a first layer such that the TIM lies between two layers of an assembly comprising a first layer and a second layer. The TIM can be applied in a single step or in at least two steps. For example, rigid particles can be applied to a first layer within a particle layer. A mixture of rigid particles and a solvent can be applied to the first layer, for example, via a glass pipette, and the solvent can then be removed, leaving the rigid particles in the first layer. The solvent may have a flash point such that it can be removed from the first layer at room temperature. For example, the solvent may include acetone. Depending on the average particle size and type of rigid particles used, applying the rigid particles before the emulsion of polymer and liquid metal droplets can reduce the aggregation of rigid particles, which can lead to improper control of bond line thickness and / or otherwise cause problems with TIM application (e.g., clogging of syringes during application).

[0041] The first layer may be a heat-generating electronic component (e.g., an integrated circuit, circuit assembly), and the second layer may be a top layer that is thermally conductive. For example, the top layer may be a heat spreader, a heat sink, or packaging. The assembly is then compressed, thereby deforming the liquid metal droplets in the TIM and forming a bond line distance between the first and second layers, which is 95% to 125% of the average particle size of the rigid particles. The TIM can be cured to form the assembly. Applying the TIM 104 in an uncured state can achieve the desired contact resistance and allow lower pressure to be used when compressing the assembly. Utilizing rigid particles allows for more effective control of the bond line distance, as the rigid particles can suppress further decreases in the distance between the first and second layers as the distance between the first and second layers approaches the average particle size of the rigid particles. For example, rigid particles can contact the first and / or second layers such that the pressure required to further decrease the distance between the first and second layers increases significantly. TIM can be applied to various layers and devices, as described below with reference to circuit assemblies and Figures 2A and 2B, but is not limited to circuit assemblies.

[0042] Referring to Figure 2A, TIM 204 may be applied to the die 206 of the circuit assembly 208, and thus TIM 204 may be between the die 206 and the upper layer 210 of the circuit assembly 200. The application of TIM 204 may occur in one or at least two steps, as described herein above. The application of TIM 204 to the die 206 may include spray coating, spin coating, dip coating, roll coating, flow coating, film coating, brush coating, extrusion, distribution, or a combination thereof. TIM 204 may be applied in an uncured state so that the TIM can be adapted to the surfaces of the die 206 and the upper layer 210, and so that a desired level of surface contact can be achieved between them. In various examples, TIM 204 may be applied directly to the die 206, and then the upper layer 210 may be applied directly to TIM 204. In various other examples, TIM 204 may be applied directly to the upper layer 210, and then the die 206 may be applied directly to TIM 204. In various examples, after application of TIM204, TIM204 can come into direct contact with the die 206 and the upper layer 210. In certain embodiments, the application of TIM204 may be limited to the surface of the die 206 so that TIM204 can be used efficiently.

[0043] As used herein, the terms “on,” “onto,” and “over,” and their variations (e.g., “applied on,” “formed on,” “deposited on,” “provided on,” “positioned on,” etc.), particularly in relation to layers, films, or materials, mean that they are applied to, formed on, deposited on, provided on, or otherwise positioned on the surface of a substrate, but not necessarily in contact with the surface of the substrate. For example, a TIM “applied” to a substrate does not exclude the presence of another layer or other layer of the same or different composition positioned between the applied TIM and the substrate. Similarly, a second layer “applied” to a first layer does not exclude the presence of another layer or other layer of the same or different composition positioned between the applied second layer and the applied TIM.

[0044] The circuit assembly 200 can be compressed. For example, referring to the detailed views of FIGS. 3A-3B, the die 206 and the upper layer 210 can be biased together such that the first distance d1 can be reduced to the second bond line distance d bl Before application and / or before the compression process, the average particle size of the liquid metal droplets 312 in the TIM 204 can be selected to be larger than the desired bond line distance d bl formed between the die 206 and the upper layer 210. For example, the average particle size of the liquid metal droplets 312 before application and / or before the compression process can be, for example, 1% larger than the bond line distance d bl 2% larger than the bond line distance d bl 5% larger than the bond line distance d bl 10% larger than the bond line distance d bl 15% larger than the bond line distance d bl 20% larger than the bond line distance d bl 30% larger than the bond line distance d bl 40% larger than the bond line distance d bl 50% larger than the bond line distance d, or 75% larger than the bond line distance d bl etc., and can be larger than the bond line distance d. The average particle size of the liquid metal droplets 312 before application and / or before the compression process can be, for example, 75% or less than the bond line distance d bl 50% or less than the bond line distance d bl 40% or less than the bond line distance d bl 30% or less than the bond line distance d bl 20% or less than the bond line distance d<000002{0}>15% or less than the bond line distance d bl 10% or less than the bond line distance d bl 5% or less than the bond line distance d bl 2% or less than the bond line distance d bl 100% or less than the bond line distance d bl etc., and can be 100% or less than the bond line distance d. The average particle size of the liquid metal droplets 312 before application and / or before the compression process can be, for example, the bond line distance d bl 100% or less than the bond line distance d bl bl blThe bond line distance d is 1% to 50% larger. bl The bond line distance d is 1% to 30% larger. bl 2% to 30% greater, or bond line distance d bl The bond line distance d is 5% to 20% larger, etc. bl It can be within a range of 1% to 100% larger.

[0045] The average particle size of the rigid particles 316 in TIM204 is determined by the desired bonding line distance, d, formed between the die 206 and the upper layer 210. bl It can be selected based on the bond line distance d bl Further reduction can be suppressed by the rigid particle 316. For example, the bonding line distance d bl This could be, for example, at least 95% of the average particle size of the rigid particles 316, such as at least 96%, at least 97%, at least 98%, at least 99%, at least 100%, or at least 101% of the average particle size of the rigid particles 316. Bond line distance d bl For example, it could be 125% or less of the average particle size of the rigid particles 316, such as 120% or less, 115% or less, 110% or less, or 105% or less of the average particle size of the rigid particles 316. For example, the bond line distance d bl For example, this can be within the range of 95% to 125% of the average particle size of the rigid particles 316, such as 95% to 120%, 95% to 110%, 100% to 120%, 100% to 110%, or 101% to 110%.

[0046] The average particle size of the liquid metal droplets 312 before application and / or before the compression process may be larger than the average particle size of the rigid particles 316, for example, by at least 5%, at least 10%, at least 20%, or at least 25%.

[0047] Compressing the circuit assembly 200 allows a compressive force to be applied to the TIM 204, which can deform the liquid metal droplets 312 dispersed within the polymer 314 of the TIM 204. Since the TIM 204 is in an uncured state, the polymer 314 remains conformable and movable so that the compressive force can deform the liquid metal droplets 312 to the size of the rigid particles 316. The liquid metal droplets 312 may remain in the liquid phase during deformation so that a lower pressure is required for compression and the desired deformation is achieved. During compression, as the first distance d1 decreases, approaching the average particle size of the rigid particles 316, the pressure required for compression increases significantly, thereby reducing the desired bond line distance d bl This demonstrates that the desired bond line distance d1 has been achieved and / or can be suppressed. In various examples, applying rigid particles 316 before the emulsion of polymer 314 and liquid metal droplets 312 can suppress the desired bond line distance d bl The aggregation of rigid particles 316, which may interfere with the control of the bond line distance d, can be reduced. bl This can enable effective control.

[0048] The compressive force can be in the range of 1 PSI to 50 PSI, for example, 2 PSI to 45 PSI, 10 PSI to 45 PSI, 15 PSI to 45 PSI, 15 PSI to 30 PSI, or 20 PSI to 40 PSI.

[0049] The liquid metal droplet 312 may be approximately spherical, as shown in Figure 3A, and then approximately ellipsoidal, as shown in Figure 3B. In various examples, the liquid metal droplet 312 before compression may have a first average aspect ratio, and after compression, the liquid metal droplet 312 may have a second average aspect ratio. The second average aspect ratio may be different from the first average aspect ratio. For example, the second average aspect ratio may be greater than the first average aspect ratio. The average aspect ratio may be the average ratio of the width to the height of the liquid metal droplet 312. In various examples, the first aspect ratio may be 1, and the second aspect ratio may be greater than 1. In certain embodiments, the first aspect ratio may be in the range of 1 to 1.5. In certain embodiments, the second aspect ratio may be at least 0.5 greater than the first aspect ratio, for example, 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. The width of the liquid metal droplet 312 may be substantially aligned with the longitudinal plane of the TIM 204 in the circuit assembly 200, and the height of the liquid metal droplet 312 may be substantially aligned with the thickness of the TIM 204 (e.g., distance, d1). The width of the liquid metal droplet 312 may increase when the circuit assembly 200 is compressed. For example, in certain embodiments, the radius of the spherical liquid metal droplet before compression may be 100 μm (e.g., first aspect ratio 1), and after compression to a bond line thickness of 20 μm, the liquid metal droplet may be deformed into an elliptical shape with a width of 316 μm (e.g., second aspect ratio 15.6).

[0050] The rigid particle 316 may be substantially spherical, as shown in Figure 3A, and thereafter can substantially maintain its sphereness, as shown in Figure 3B. In various examples, the rigid particle 316 before compression may have a third mean aspect ratio, and after compression, the rigid particle 316 can substantially maintain the third mean aspect ratio. In various examples, the third mean aspect ratio may be in the range of 0.9 to 1.1, for example, the third mean aspect ratio may be 1. The second mean aspect ratio of the liquid metal droplet 312, as shown in Figure 3B, may be greater than the third mean aspect ratio of the rigid particle as shown in Figure 3B, for example, at least 0.5 greater than the third aspect ratio, at least 1 greater than the third aspect ratio, at least 2 greater than the third aspect ratio, or at least 5 greater than the third aspect ratio, for example, at least 0.1 greater than the third aspect ratio.

[0051] In various embodiments, the rigid particles 316 may include an average sphericity of at least 0.9, such as at least 0.95, at least 0.96, at least 0.97, at least 0.98, or at least 0.99. The rigid particles 316 may be substantially uniform in size. For example, the rigid particles 316 may have a D 50 D of rigid particles 316 such as 125% or less, 120% or less, 115% or less, or 110% or less. 50 D is less than 125% of 90 It may include the rigid particle 316, for example, D of the rigid particle 316 50 At least D of rigid particles 316, such as 125% or less, at least 101%, at least 105%, or at least 110%. 50 D 90 It may include, for example, rigid particle 316, for example, D of rigid particle 316 50 At least D of the rigid particles 316, such as 101%~120%, 101%~115%, 101%~110%, 101%~105%, or 100%~105%. 50 From rigid particle 316 D 50 D is within the range of 125%90 This includes the rigid particle 316, for example, D of the rigid particle 316. 50 D of rigid particles 316, such as at least 95%, at least 98%, or at least 99%. 50 at least 90% of D 10 It may include the rigid particle 316, for example, D of the rigid particle 316 50 D of rigid particles 316, such as 99% or less, 98% or less, or 95% or less. 50 The following D 10 It may include, for example, rigid particle 316, for example, D of rigid particle 316 50 D of rigid particles 316, such as 90%~99%, 95%~99%, 95%~100%, 98%~100%, or 99%~100%. 50 90% of rigid particles 316 D 50 D within the range up to 10 This may include: Therefore, due to the uniformity and shape of the rigid particles 316, the orientation of the rigid particles 316 is determined by the bond line distance d bl It may not have any effect.

[0052] In various examples, the liquid metal droplet 312 and the rigid particle 316 have, for example, a bonding line distance d bl 90%~100%, 90%~99%, 95%~99%, 95%~100%, 98%~100%, or 99%~100%, etc., the bond line distance d bl 85% of ~ bond line distance d bl This may include the average height (when measured in the direction from die 206 to upper layer 210) which is within 100% of the range.

[0053] In a particular example, the liquid metal droplets 312 and rigid particles 316 can be aligned substantially as a single layer after compression, as shown in Figure 3B. The single layer is defined by the average particle size of the liquid metal droplets 312, the average particle size of the rigid particles 316, and the bonding line distance d bl This can be achieved by selecting the following: Constituting liquid metal droplets 312 and rigid particles 316 in a single layer can reduce the thermal resistance of TIM204.

[0054] TIM204 can be cured to form the circuit assembly 200. Curing TIM204 can increase the viscosity of polymer 314 and make polymer 314 harder. For example, polymer 316 can become solid. In various examples, the cured polymer 314 is an elastomer. Curing polymer 314 can suppress pumping from liquid metal droplets 312 during the thermal cycling of the circuit assembly 200 and can provide a mechanical bond between die 206 and upper layer 210.

[0055] The assembly 200 has a bond line distance d formed between the die 206 and the upper layer 210 in a cured assembly of 150 microns or less, such as 145 microns or less, 140 microns or less, 120 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 This may include: The assembly 200 has a bond line distance d formed between the die 206 and the upper layer 210 in the cured assembly, which is at least 15 microns, such as at least 30 microns, at least 35 microns, at least 40 microns, at least 50 microns, at least 70 microns, at least 80 microns, at least 100 microns, at least 120 microns, at least 140 microns, or at least 145 microns. bl This may include: The assembly 200 has a bond line distance d formed between the die 206 and the upper layer 210 in the cured assembly, which is in the range of 15 to 150 microns, such as 15 to 90 microns, 15 to 70 microns, 30 to 70 microns, 35 to 70 microns, or 15 to 100 microns. bl It can include...

[0056] Hardening can occur over a first period and compression can occur over a second period. The first period can be after the second period or can at least partially overlap with the second period. For example, the liquid metal droplet 312 can be deformed before substantial hardening of the polymer 314, so that a lower compression pressure can be used to deform the liquid metal droplet 312.

[0057] The average particle size of the liquid metal droplets 314, the average particle size of the rigid particles 316, and the deformation of the liquid droplets 312 can improve the thermal resistance value of TIM204. For example, the TIM204 after hardening can have a thermal resistance value of, for example, 30 (°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 2 ) / W or less. The TIM204 after hardening can have a thermal resistance value of, for example, at least 0.5 (°K*mm 2 ) / W, 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 TIM204 after hardening can have a thermal resistance value of, for example, 0.5 (°K*mm 2 ) / W to 20 (°K*mm 2 ) / W, 0.5 (°K*mm 2 ) / W to 15 (°K*mm 2 ) / W, 1 (°K*mm 2 ) / W to 10 (°K*mm 2 ) / W, 2 (°K*mm 2 ) / W to 10 (°K*mm 2 ) / W, or 2 (°K*mm 2 ) / W to 8 (°K*mm 2 ) / W. 2) / W etc, 0.5(°K*mm 2 ) / W~30(°K*mm 2 This may include thermal resistance values ​​within the range of ) / W. Thermal resistance values ​​can be measured using a DynTIM-S instrument available from Siemens (Munich, Germany), a TIMA instrument from NanoTest (Germany), and / or a LongWin LW 9389 (Taiwan).

[0058] The die 206 may comprise an integrated circuit, such as a processor, ASIC, or system-on-a-chip (SOC). The upper layer 210 may be an integrated heat spreader. TIM 204 may be applied directly between the processor and the integrated heat spreader. For example, TIM 204 may be TIM 1, TIM 1.5, or a combination thereof. TIM 1 can be used to thermally connect the die and the integrated heat spreader in a covered package. TIM 1.5 can be used to thermally connect the die to a heat sink in a bare die package.

[0059] In various other examples, referring to Figure 2B, TIM216 may be applied between upper layer 210 (e.g., integrated heat spreader) and a different upper layer 218. The upper layer 218 may include a heat sink. For example, TIM216 could be TIM2.

[0060] In various other examples, the TIM according to this disclosure can be used in a system on a package. For example, a single horizontal TIM layer may be in contact with multiple dies on one side (e.g., an integrated circuit may comprise multiple dies, or multiple integrated circuits may be in contact with the same side of the TIM), or in contact with upper layers or multiple layers on different sides.

[0061] <Examples>

[0062] This disclosure will be better understood by referring to the following examples, which provide exemplary and non-limiting aspects of this disclosure. It should be understood that the disclosures described herein are not necessarily limited to the examples described in this section.

[0063] Table 1 below shows the results of testing the control of bond line distance within assemblies for three different example TIM formulations.

[0064] [Table 1]

[0065] Each TIM example formulation was applied to the first layer of the assembly, and the second layer of the assembly was also applied to the TIM formulation. Then, a compression pressure of either 15 PSI or 29 PSI was used to compress the assembly. The pressure was applied until the TIM formulation could no longer be compressed at that pressure, and the thickness of the resulting bond line after compression was measured. This procedure was repeated multiple times for each example formulation.

[0066] Comparative Formulation 1 was observed to have little control over the bond line thickness at either 15 PSI or 29 PSI, minimizing the distance between the first and second layers. Comparative Formulation 2 was observed to favorably control the bond line thickness at both 15 PSI and 29 PSI compared to Comparative Formulation 1, such that the average bond line thickness was similar to the median diameter of the glass rigid particles. Comparative Formulation 3 was observed to favorably control the bond line thickness at both 15 PSI and 29 PSI compared to Comparative Formulation 1, such that the average bond line thickness was similar to the median diameter of the glass rigid particles. In addition, the compression pressure at 29 PSI was observed in Comparative Formulations 2 and 3 to achieve a more uniform bond line thickness.

[0067] The morphology of Example Formulation Comparative 1 is shown in Figure 4A, and the morphology of Example Formulation 2 is shown in Figure 4B. It was observed that the morphology of Example Formulation 2 was substantially unaffected by the addition of glass-rigid particles compared to Example Formulation Comparative 1.

[0068] The various aspects of the present invention described herein, without limitation, include those listed in the following numbered clauses.

[0069] 1. A method comprising: applying a thermal interface material onto a die of a circuit assembly such that the thermal interface material is between the die of the circuit assembly and the upper layer, wherein the thermal interface material applied to the die comprises an emulsion of liquid metal droplets, an uncured polymer, and rigid particles, and the liquid metal droplets are in the liquid phase at a temperature in the range of at least -20°C to 30°C; compressing the circuit assembly, thereby deforming the liquid metal droplets and forming a bond line distance between them and the upper layer, which is 95% to 125% of the average particle size of the rigid particles, wherein the average particle size of the liquid metal droplets in the thermal interface material before application is greater than the average particle size of the rigid particles; and curing the thermal interface material, thereby forming a cured assembly.

[0070] 2. A method comprising: applying rigid particles onto a die of a circuit assembly; applying an emulsion of an uncured polymer and liquid metal droplets onto the die of the circuit assembly together with the applied rigid particles, thereby forming a thermal interface material between the die of the circuit assembly and the upper layer, wherein the liquid metal droplets are in the liquid phase at a temperature in the range of at least -20°C to 30°C; compressing the circuit assembly, thereby deforming the liquid metal droplets, thereby forming a bond line distance between the die and the upper layer that is 95% to 125% of the average particle size of the rigid particles, wherein, prior to application, the average particle size of the liquid metal droplets in the thermal interface material is greater than the average particle size of the rigid particles; and curing the thermal interface material, thereby forming a cured assembly.

[0071] 3. The method according to clause 1 or 2, wherein the die comprises a processor.

[0072] 4. The method according to any one of the clauses 1 to 3, wherein the upper layer comprises an integrated heat spreader for the processor.

[0073] 5. The method according to any one of the clauses 1 to 4, wherein the upper layer comprises a heat sink, an integrated heat spreader, or packaging.

[0074] 6. The method according to any one of the claims 1 to 5, wherein the bond line distance formed between the die and the upper layer in the curing assembly is 150 microns or less.

[0075] 7. The method according to any one of the claims 1 to 6, wherein the bond line distance formed between the die and the upper layer in the curing assembly is 100 microns or less.

[0076] 8. The method according to any one of the claims 1 to 7, wherein the bond line distance formed between the die and the upper layer in the curing assembly is 70 microns or less.

[0077] 9. The method according to any one of the claims 1 to 8, wherein the bond line distance formed between the die and the upper layer in the curing assembly is in the range of 15 microns to 90 microns.

[0078] 10. The method according to any one of the claims 1 to 9, wherein the average particle size of liquid metal droplets in the thermal interface material before application is greater than the bond line distance formed between the die and the upper layer in the curing assembly.

[0079] 11. The method according to any one of the claims 1 to 10, wherein the average particle size of liquid metal droplets in the thermal interface material before deposition is within the range of 1% to 100% greater than the bond line distance formed between the die and the upper layer during the curing assembly.

[0080] 12. The method according to any one of the clauses 1 to 11, wherein the liquid metal droplets include gallium, gallium alloys, indium, indium alloys, tin, tin alloys, mercury, mercury alloys, or a combination thereof.

[0081] 13. The thermal interface material after curing is 30 (°K*mm 2 The method described in any one of clauses 1 to 12, including a thermal resistance value of ) / W or less.

[0082] 14. The thermal interface material after curing is 10 (°K*mm 2 The method described in any one of clauses 1 to 13, including a thermal resistance value of ) / W or less.

[0083] 15. The method according to any one of the clauses 1 to 14, wherein the liquid metal droplets include monomodal polydispersibility.

[0084] 16. The method according to any one of the clauses 1 to 14, wherein the liquid metal droplets include multi-modal dispersion.

[0085] 17. The method according to any one of the clauses 1 to 16, wherein the polymer includes a thermosetting polymer.

[0086] 18. The method according to any one of the clauses 1 to 17, wherein the polymer includes a thermoplastic polymer.

[0087] 19. The method according to any one of the claims 1 to 18, wherein the emulsion has a viscosity of less than 850,000 cP before curing.

[0088] 20. The method according to any one of the clauses 1 to 19, wherein the liquid metal droplets are substantially spherical before deposition and substantially ellipsoidal after assembly compression.

[0089] 21. The method according to any one of the clauses 1 to 20, wherein the liquid metal droplets and rigid particles each have an average height within the range of 85% to 100% of the bond line distance after assembly compression.

[0090] 22. The method according to any one of the claims 1 to 21, wherein the thermal interface material comprises 30 to 92 volume percent liquid metal droplets, 0.1 to 5 volume percent rigid particles, and 7 to 70 volume percent polymer.

[0091] 23. The method according to any one of clauses 1 to 22, wherein hardening occurs over a first period, compression occurs over a second period, and the first period is after the second period or at least partially overlaps with the second period.

[0092] 24. The method according to any one of clauses 1 to 23, wherein the rigid particles have an average particle size within the range of 1 micron to 150 microns.

[0093] 25. The method according to any one of clauses 1 to 24, wherein the bond line distance between the die and the upper layer is 100% to 110% of the average particle size of the rigid particles.

[0094] 26. The method according to any one of clauses 1 to 25, wherein the rigid particles have a sphericity of at least 0.9.

[0095] 27. The method according to any one of clauses 1 to 26, wherein the rigid particles include iron, iron alloy, vanadium, vanadium alloy, niobium, niobium alloy, titanium, titanium alloy, copper, copper alloy, rigid polymer, glass, ceramic, or a combination thereof.

[0096] 28. The method according to any one of clauses 1 to 27, wherein the liquid metal droplets include gallium, gallium alloy, indium, indium alloy, tin, tin alloy, mercury, mercury alloy, or a combination thereof.

[0097] 29. The method according to any one of clauses 1 to 28, wherein the rigid particles have a Young's modulus of at least 100 MPa.

[0098] 30. The method according to any one of clauses 1 to 29, wherein the rigid particles include D 50 that is 125% or less of D 90 of the rigid particles.

[0099] 31. The method according to any one of clauses 1 to 30, wherein the rigid particles are substantially spherical before deposition and after assembly compression.

[0100] 32. A circuit assembly manufactured by any one of the methods described in any one of the clauses 1 to 31.

[0101] 33. An assembly comprising a die, an upper layer, and a thermal interface material disposed in contact with the die layer and the upper layer, wherein the thermal interface material comprises a polymer, liquid metal droplets, and rigid particles, the bond line distance formed between the die and the upper layer is 95% to 125% of the average particle size of the rigid particles, the liquid metal droplets have a first aspect ratio, the rigid spheres have a second aspect ratio, the first aspect ratio is greater than the second aspect ratio, and the liquid metal droplets are in the liquid phase at temperatures within the range of at least -20 degrees Celsius to 30 degrees Celsius.

[0102] 34. The assembly described in Clause 33, wherein the die comprises a processor.

[0103] 35. The assembly described in Clause 33 or 34, wherein the upper layer comprises a heat sink, an integrated heat spreader, or packaging.

[0104] 36. An assembly according to any one of clauses 33 to 35, wherein the bond line distance formed between the die and the upper layer in the assembly is 150 microns or less.

[0105] 37. An assembly according to any one of clauses 33 to 36, wherein the bond line distance formed between the die and the upper layer in the assembly is 100 microns or less.

[0106] 38. An assembly according to any one of clauses 33 to 37, wherein the bond line distance formed between the die and the upper layer in the assembly is 70 microns or less.

[0107] 39. An assembly according to any one of clauses 33 to 38, wherein the bond line distance formed between the die and the upper layer in the assembly is in the range of 15 microns to 90 microns.

[0108] 40. An assembly according to any one of the clauses 33 to 39, wherein the liquid metal droplets include gallium, gallium alloys, indium, indium alloys, tin, tin alloys, mercury, mercury alloys, or a combination thereof, and / or the rigid particles include iron, iron alloys, vanadium, vanadium alloys, niobium, niobium alloys, titanium, titanium alloys, copper, copper alloys, polymers, glass, ceramics, or a combination thereof.

[0109] 41. An assembly according to any one of the clauses 33 to 40, wherein liquid metal droplets and rigid particles are dispersed throughout the polymer.

[0110] 42. An assembly according to any one of the clauses 33 to 41, wherein the thermal interface material comprises 30% to 92% by volume of liquid metal droplets, 0.1% to 5% by volume of rigid particles, and 7% to 70% by volume of polymer.

[0111] 43. Thermal interface material, 30 (°K*mm 2 An assembly as described in any one of clauses 33 to 42, including a thermal resistance value of ) / W or less.

[0112] 44. Thermal interface material, 10 (°K*mm 2 An assembly as described in any one of clauses 33 to 43, including a thermal resistance value of ) / W or less.

[0113] 45. An assembly according to any one of clauses 33 to 44, wherein the liquid metal droplets include monomodal polydispersibility.

[0114] 46. ​​An assembly according to any one of clauses 33 to 44, wherein the liquid metal droplets include multi-modal dispersion.

[0115] 47. An assembly according to any one of the clauses 33 to 46, wherein the polymer includes a thermosetting polymer.

[0116] 48. An assembly according to any one of the clauses 33 to 47, wherein the polymer includes a thermoplastic polymer.

[0117] 49. An assembly according to any one of the clauses 33 to 48, wherein the liquid metal droplets are substantially ellipsoidal and the rigid particles are substantially spherical.

[0118] 50. An assembly according to any one of the clauses 33 to 49, wherein the rigid particles have a Young's modulus of at least 100 MPa.

[0119] 51. An assembly according to any one of clauses 33 to 50, wherein the rigid particles include an average particle size in the range of 1 micron to 150 microns.

[0120] 52. An assembly according to any one of clauses 33 to 51, wherein the bond line distance between the die and the upper layer is 100% to 110% of the average particle size of the rigid particles.

[0121] 53. An assembly according to any one of clauses 33 to 52, wherein the rigid particles include a sphere of at least 0.9.

[0122] 54. An assembly as described in any one of Clauses 33 to 53, wherein the rigid particles include iron, iron alloys, vanadium, vanadium alloys, niobium, niobium alloys, titanium, titanium alloys, copper, copper alloys, rigid polymers, glass, ceramics, or a combination thereof.

[0123] 55. Rigid particles, D of rigid particles 50 D is less than 125% of 90 An assembly as described in any one of clauses 33 to 54, including the assembly described in any one of clauses 33 to 54.

[0124] 56. An assembly according to any one of clauses 33 to 55, wherein the rigid particles are substantially spherical before deposition and after assembly compression.

[0125] 57. Apparatus for thermally connecting a die and an upper layer, the apparatus comprising a container defining a cavity and an emulsion disposed within the cavity, wherein the emulsion comprises liquid metal droplets, rigid particles, and an uncured polymer, the container is configured to allow application of the emulsion onto a die of a circuit assembly, the average particle size of the liquid metal droplets is greater than the average particle size of the rigid particles, and the liquid metal droplets are in the liquid phase at temperatures in the range of at least -20 degrees Celsius to 30 degrees Celsius.

[0126] 58. A system for thermally connecting a die and an upper layer, the system comprising a container defining a first cavity and a second container defining a second cavity, wherein the first container contains an emulsion disposed within the first cavity, the emulsion contains liquid metal droplets and an uncured polymer, the first container is configured to allow application of the emulsion onto the die of the circuit assembly, the liquid metal droplets are in the liquid phase at a temperature in the range of at least -20°C to 30°C, the second container contains a mixture of rigid particles and a solvent, the second container is configured to allow application of the mixture onto the die of the circuit assembly, the average particle size of the liquid metal droplets is greater than the average particle size of the rigid particles.

[0127] 59. The apparatus according to Clause 57, which is the system according to Clause 58, wherein the container is a syringe or at least one of the first container and the second container is a syringe.

[0128] 60. The apparatus according to Clause 57, which is the system according to Clause 58, wherein the container is a pillow pack or at least one of the first container and the second container is a pillow pack.

[0129] 61. A device according to any one of clauses 57 and 59-60, or a system according to any one of clauses 58 and 59-60, wherein the die comprises a processor.

[0130] 62. An apparatus as described in any one of Clauses 57 and 59-61, or a system as described in any one of Clauses 58 and 59-61, wherein the upper layer comprises a heat sink, an integrated heat spreader, or packaging.

[0131] 63. An apparatus according to any one of clauses 57 and 59-62, or a system according to any one of clauses 58 and 59-62, wherein the average particle size of liquid metal droplets in the emulsion is greater than the bond line distance formed between the die and the upper layer of the circuit assembly.

[0132] 64. Apparatus as described in any one of Clauses 57 and 59-63, or system as described in any one of Clauses 58 and 59-63, wherein the liquid metal droplets include gallium, gallium alloys, indium, indium alloys, tin, tin alloys, mercury, mercury alloys, or a combination thereof.

[0133] 65. An apparatus according to any one of clauses 57 and 59-63, or a system according to any one of clauses 58 and 59-63, wherein the liquid metal droplet is in the liquid phase at a temperature within the range of at least -20 degrees Celsius to 30 degrees Celsius.

[0134] 66. Apparatus according to any one of clauses 57 and 59-65, or system according to any one of clauses 58 and 59-65, wherein the liquid metal droplets include monomodal polydispersibility.

[0135] 67. Apparatus according to any one of clauses 57 and 59-65, or system according to any one of clauses 58 and 59-65, wherein liquid metal droplets exhibit multi-modal dispersion.

[0136] 68. An apparatus according to any one of clauses 57 and 59-67, or a system according to any one of clauses 58 and 59-67, wherein the polymer includes a thermosetting polymer.

[0137] 69. An apparatus according to any one of clauses 57 and 59-68, or a system according to any one of clauses 58 and 59-68, wherein the emulsion has a viscosity of less than 250,000 cP before curing.

[0138] 70. Apparatus as described in any one of Clauses 57 and 59-69, or system as described in any one of Clauses 58 and 59-69, wherein the liquid metal droplets are substantially spherical.

[0139] 71. An apparatus or system according to any one of clauses 57 and 59-70, wherein the rigid particles include an average particle size in the range of 1 micron to 150 microns.

[0140] 72. The apparatus or system according to any one of clauses 57 and 59-71, wherein the bond line distance between the die and the upper layer is 100% to 110% of the average particle size of the rigid particles.

[0141] 73. An apparatus or system according to any one of clauses 57 and 59-72, wherein the rigid particles have a sphere of at least 0.9.

[0142] 74. Apparatuses or systems according to any one of Clauses 57 and 59-73, wherein the rigid particles include iron, iron alloys, vanadium, vanadium alloys, niobium, niobium alloys, titanium, titanium alloys, copper, copper alloys, rigid polymers, glass, ceramics, or any combination thereof.

[0143] 75. An apparatus or system according to any one of clauses 57 and 59-74, wherein the rigid particles have a Young's modulus of at least 100 MPa.

[0144] 76. Rigid particles, D of rigid particles 50 D is less than 125% of 90Apparatus as described in any one of clauses 57 and 59-75, or system as described in any one of clauses 58 and 59-75.

[0145] 77. An apparatus or system according to any one of clauses 57 and 59-76, wherein the rigid particles are substantially spherical.

[0146] 78. Apparatus or system according to any one of Clauses 57 and 59-77, wherein liquid metal droplets and rigid particles individually have an average height in the range of 85% to 100% of the bond line distance after assembly compression.

[0147] 79. An assembly comprising a first layer such as a die, a second layer such as an upper layer, and a thermal interface material disposed in contact with the first and second layers, wherein the thermal interface material comprises a polymer, liquid metal droplets, and rigid particles, the liquid metal droplets having a first aspect ratio, and the rigid particles having a second aspect ratio, the first aspect ratio being greater than the second aspect ratio, such as at least greater than 0.1, at least greater than 0.5, at least greater than 1, at least greater than 2, or at least greater than 5, the liquid metal droplets being in the liquid phase at a temperature in the range of at least -20°C to 30°C, the bond line distance between the first and second layers being 95% to 125% of the average particle size of the rigid particles, and optionally the thermal interface material comprising 30% to 92% by volume of liquid metal droplets, 0.1% to 5% by volume of rigid particles, and 7% to 70% by volume of polymer - an assembly comprising, optionally, rigid particles having a Young's modulus of at least 100 MPa, 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, or at least 2 GPa; optionally, liquid metal droplets comprising gallium, gallium alloys, indium, indium alloys, tin, tin alloys, mercury, mercury alloys, or combinations thereof; rigid particles comprising iron, iron alloys, such as stainless steel, vanadium, vanadium alloys, niobium, niobium alloys, titanium, titanium alloys, copper, copper alloys, polymers, glass, ceramics, or combinations thereof; optionally, liquid metal droplets and rigid particles dispersed throughout the polymer; optionally, the average particle size of the rigid particles may be in the range of 1 micron to 150 microns.

[0148] 80. A method for producing an assembly according to Clause 79, comprising: applying a thermal interface material on a first layer such that the thermal interface material is between a first layer and a second layer, wherein the application of the thermal interface material includes, optionally, applying rigid particles on the first layer; applying an emulsion of an uncured polymer and liquid metal droplets on the first layer having the applied rigid particles, thereby forming a thermal interface material between the first layer and the second layer; applying an emulsion of a polymer, liquid metal droplets and rigid particles on the first layer, or a combination thereof; compressing the circuit assembly, thereby deforming the liquid metal droplets, and forming a bond line distance between the first layer and the second layer which is 95% to 125% of the average particle size of the rigid particles, wherein the average particle size of the liquid metal droplets in the thermal interface material before application is greater than the average particle size of the rigid particles; and curing the thermal interface material, thereby forming a cured assembly.

[0149] Those skilled in the art will recognize that the compositions, articles, methods, and accompanying considerations described herein are used as examples for conceptual clarity, and that various configuration modifications are intended. Consequently, when used herein, the specific examples and accompanying considerations described are intended to represent a more general class. In general, the use of any specific example is intended to represent that class, and the exclusion of specific components (e.g., operations), devices, and objects should not be considered limiting.

[0150] Those skilled in the art will understand that, with respect to the attached claims, the operations listed therein can generally be performed in any order. Furthermore, while various operation flows are presented in the sequence, it should be understood that various operations can be performed in orders other than those illustrated, or simultaneously. Examples of such alternative orderings include, unless otherwise specified by the context, overlapping, interleaving, interrupting, rearranging, incrementing, preparing, complementing, simultaneous, reverse, or other variable orderings. Moreover, terms such as “responding to,” “related to,” or other past tense adjectives are generally not intended to exclude such variations unless otherwise specified by the context.

[0151] While various examples are described herein, many modifications, variations, substitutions, alterations, and equivalents of those examples may be implemented and will occur to those skilled in the art. Furthermore, if a material is disclosed with respect to a particular component, other materials may be used. Therefore, it should be understood that the foregoing description and the accompanying claims are intended to cover all such modifications and variations that fall within the scope of the disclosed embodiments. The following claims are intended to cover all such modifications and variations.

[0152] To provide an understanding of the compositions, structures, manufactures, functions, and / or operations of the present invention, including the disclosed compositions, coatings, and methods, various features and properties are described herein. It should be understood that the various features and properties of the present invention described herein can be combined in any preferred manner, whether such features and properties are expressly described herein in combination. The inventors and applicants expressly intend that any combination of such features and properties falls within the scope of the present invention as described herein. Thus, the claims can be amended to enumerate any features and properties expressly or essentially described herein, or otherwise expressly or essentially supported herein, in any combination. Furthermore, the applicant reserves the right to amend the claims to affirmatively negate features and properties that may exist in the prior art, even if these features and properties are not expressly described herein. Accordingly, any such amendment does not add new matter to the specification or claims and is subject to the requirements of written description, sufficiency of description, and added matter.

[0153] Any numerical range enumerated herein describes all subranges of the same numerical precision (i.e., having the same number of specified digits) that fall within the enumerated range. For example, the enumerated range "1.0 to 10.0" describes all subranges (including their upper and lower limits) from the enumerated minimum value of 1.0 to the enumerated maximum value of 10.0, such as "2.4 to 7.6," even if the range "2.4 to 7.6" is not explicitly enumerated in the text of this specification. Accordingly, the applicant reserves the right to amend this specification, including the claims, to explicitly enumerate any subranges of the same numerical precision that fall within the ranges explicitly enumerated herein. All such ranges are essentially described herein, and therefore any amendment to explicitly enumerate any such subranges shall be subject to the requirements of written description, sufficiency of description, and added matter.

[0154] Furthermore, unless explicitly specified or otherwise required by the context, all numerical parameters described herein (such as values, ranges, quantities, percentages, etc.) can be read as if the word "approximately" is prepended, even if the word "approximately" does not explicitly appear before the numerical value. In addition, numerical parameters described herein should be interpreted by applying the reported number of significant figures, numerical precision, and standard rounding techniques. It should also be understood that numerical parameters described herein inevitably have the inherent variability characteristics of the underlying measurement techniques used to determine the numerical values ​​of the parameters.

[0155] While the numerical ranges and parameters describing the broad scope of this invention are approximations, the numerical values ​​described in specific examples are reported as accurately as possible. However, any numerical value inherently contains certain errors that inevitably arise from the standard variations found in each test measurement.

[0156] Throughout this specification, references to “various examples,” “several examples,” “one example,” or “example” mean that certain features, structures, or characteristics described in relation to an example are included in that example. Therefore, the occurrence of phrases such as “various examples,” “several examples,” “one example,” or “in one example” in their usual place throughout this specification does not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics may be combined in any preferred manner in one or more examples. Therefore, certain features, structures, or characteristics illustrated or described in relation to one example may, in whole or in part, be combined with features, structures, or characteristics of another example or other examples, though not limited to these. Such modifications and variations are intended to be included within the scope of this embodiment.

[0157] Any patent, publication, or other document identified herein is incorporated in whole by reference, unless otherwise indicated, provided that the incorporated material does not conflict with any existing descriptions, definitions, statements, illustrations, or other disclosures expressly contained herein. Therefore, to the extent necessary, express disclosures contained herein take precedence over any conflicting material incorporated by reference. Any material, or any part thereof, incorporated by reference but conflicting with any existing definitions, statements, or other disclosures contained herein is incorporated only insofar as it does not create a conflict between the incorporated material and the existing disclosures. The applicant reserves the right to amend this specification to expressly enumerate any subject matter or part thereof incorporated by reference. Any amendment to this specification to add such incorporated subject matter shall be subject to the requirements of written description, sufficiency of description, and added subject matter.

[0158] While specific examples of the present invention have been described above for illustrative purposes, it will be apparent to those skilled in the art that many modifications of the details of the present invention can be made without departing from the present invention as defined in the appended claims.

[0159] This disclosure provides descriptions of various specific embodiments for the purpose of illustrating various aspects and / or potential uses thereof, but those skilled in the art should understand that variations and modifications will occur. Accordingly, it should be understood that the inventions or any of the inventions described herein are at least as broad as they are claimed and are not more narrowly defined by the specific exemplary embodiments provided herein.

[0160] It should be understood that the inventions described herein are not limited to the embodiments summarized in the summary or detailed description. Various other embodiments are described and illustrated herein.

Claims

1. It is a method, Applying rigid particles to the die of the circuit assembly, An emulsion of an uncured polymer and liquid metal droplets is applied onto the die of the circuit assembly having the applied rigid particles, thereby forming a thermal interface material between the die and the upper layer of the circuit assembly, wherein the liquid metal droplets are in the liquid phase at a temperature within the range of at least -20 degrees Celsius to 30 degrees Celsius. The circuit assembly is compressed to deform the liquid metal droplets, thereby forming a bond line distance between the die and the upper layer that is 95% to 125% of the average particle size of the rigid particles, wherein, prior to application, the average particle size of the liquid metal droplets in the thermal interface material is larger than the average particle size of the rigid particles. A method comprising curing the thermal interface material to form a cured assembly.

2. The method according to claim 1, wherein the bond line distance formed between the die and the upper layer in the curing assembly is 150 microns or less.

3. The method according to claim 1, wherein the rigid particles include an average particle size in the range of 1 micron to 150 microns.

4. The method according to claim 1, wherein the bond line distance between the die and the upper layer is 100% to 110% of the average particle size of the rigid particles.

5. The method according to claim 1, wherein the rigid particles have a sphericity of at least 0.

9.

6. The method according to claim 1, wherein the rigid particles include iron, iron alloys, vanadium, vanadium alloys, niobium, niobium alloys, titanium, titanium alloys, copper, copper alloys, rigid polymers, glass, ceramics, or combinations thereof, and the liquid metal droplets include gallium, gallium alloys, indium, indium alloys, tin, tin alloys, mercury, mercury alloys, or combinations thereof.

7. The method according to claim 1, wherein the rigid particles have a Young's modulus of at least 100 MPa.

8. The rigid particle is the D of the rigid particle. ５０ D is less than 125% of ９０ The method according to claim 1, including the method described in claim 1.

9. The method according to claim 1, wherein the die comprises a processor, and the upper layer comprises a heat sink, an integrated heat spreader, or packaging.

10. The method according to claim 1, wherein the liquid metal droplets are substantially spherical before deposition, the liquid metal droplets are substantially ellipsoidal after assembly compression, and the rigid particles are substantially spherical before deposition and after assembly compression.

11. The method according to claim 1, wherein the thermal interface material comprises 30% to 92% by volume of the liquid metal droplets, 0.1% to 5% by volume of the rigid particles, and 7% to 70% by volume of the polymer.

12. The method according to claim 1, wherein the liquid metal droplets include an average height within the range of 85% to 100% of the bonding line distance.

13. In a method for manufacturing an assembly, The aforementioned assembly is The first layer, including the die, The second layer, such as the upper layer, A thermal interface material disposed in contact with the first layer and the second layer, It includes, The thermal interface material comprises a polymer, liquid metal droplets, and rigid particles. Optionally, the thermal interface material comprises 30% to 92% by volume of the liquid metal droplets, 0.1% to 5% by volume of the rigid particles, and 7% to 70% by volume of the polymer. Optionally, the rigid particles include a Young's modulus of at least 100 MPa, 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, or at least 2 GPa. Optionally, the liquid metal droplets include gallium, gallium alloys, indium, indium alloys, tin, tin alloys, mercury, mercury alloys, or combinations thereof, and the rigid particles include iron such as stainless steel, iron alloys, vanadium, vanadium alloys, niobium, niobium alloys, titanium, titanium alloys, copper, copper alloys, polymers, glass, ceramics, or combinations thereof. The liquid metal droplets and rigid particles are optionally dispersed throughout the polymer. The bond line distance between the first layer and the second layer is 95% to 125% of the average particle size of the rigid particles, and optionally the average particle size of the rigid particles may be in the range of 1 micron to 150 microns. The liquid metal droplet has a first aspect ratio, and the rigid sphere has a second aspect ratio, wherein the first aspect ratio is greater than the second aspect ratio by at least 0.1, at least 0.5, at least 1, at least 2, or at least 5, etc. The aforementioned liquid metal droplet is in the liquid phase at a temperature within the range of at least -20 degrees Celsius to 30 degrees Celsius. The aforementioned method, The thermal interface material is applied on the first layer such that it lies between the first layer and the second layer, and the application of the thermal interface material is optional. Applying rigid particles onto the first layer, applying an emulsion of an uncured polymer and liquid metal droplets onto the first layer having the applied rigid particles, thereby forming a thermal interface material between the first layer and the second layer. Applying the emulsion of the polymer, liquid metal droplets, and rigid particles onto the first layer, or This includes applying these combinations, Compressing the assembly, thereby deforming the liquid metal droplets, and forming the bond line distance between the first layer and the second layer, which is 95% to 125% of the average particle size of the rigid particles, The formation of liquid metal droplets in the thermal interface material before application is such that the average particle size of the liquid metal droplets is larger than the average particle size of the rigid particles. The thermal interface material is cured, thereby forming a cured assembly. Methods that include...

Images