Phosphonic acid for enhancing performance of thermal interface materials

Abstract

The present disclosure relates to phosphonic acids for enhancing the performance of thermal interface materials. Specifically, the present invention relates to the use of phosphonic acid for enhancing the performance of thermal interface materials (generalized, composites), for example by improving rheological properties, improving aging properties, improving shelf life, improving stickiness / adhesion, and / or reducing diffusion of materials (if any) migrating therefrom (e.g., reduced diffusion of oil exudate, etc. The present disclosure also relates to methods of enhancing the performance of composites for managing thermal and / or electromagnetic interference (EMI) using phosphonic acid. The composites may include thermal management and / or electromagnetic interference (EMI) mitigation materials, such as thermal interface materials (TIMs), EMI absorber materials, thermally conductive EMI absorber materials, electrically conductive materials, combinations thereof, etc.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the use of phosphonic acids to enhance the performance of thermal interface materials (broadly, composites), for example, by improving rheological properties, improving aging properties, improving shelf life, improving tack / adhesion, and / or reducing diffusion of materials (if any) migrating therefrom (e.g., reduced oil exudate diffusion, etc.). BACKGROUND

[0002] This section provides background information relating to the present disclosure, which is not necessarily prior art.

[0003] Electrical components, such as semiconductors, integrated circuit packages, transistors, etc., typically have pre-designed temperatures at which the electrical components operate optimally. Ideally, the pre-designed temperatures are close to the temperature of the surrounding air. However, the operation of electrical components generates heat. If the heat is not removed, the electrical components can operate at temperatures significantly higher than their normal or desired operating temperatures. Such excessively high temperatures can adversely affect the operational characteristics of the electrical components and the operation of the associated devices.

[0004] To avoid or at least reduce adverse operational characteristics from heat generation, the heat should be removed, for example, by conducting the heat from the operating electrical components to a heat sink. The heat sink can then be cooled by conventional convection and / or radiation techniques. During conduction, heat can be transferred from the operating electrical components to the heat sink through direct surface contact between the electrical components and the heat sink and / or through contact of the electrical components and the heat sink surfaces via an intermediate medium or thermal interface material (TIM). Thermal interface materials can be used to fill the gaps between the heat transfer surfaces in order to increase the efficiency of heat transfer as compared to filling the gaps with air, which is a relatively poor thermal conductor.

[0005] Additionally, a common problem in the operation of electronic devices is the generation of electromagnetic radiation within the electronic circuitry of the device. This radiation can cause electromagnetic interference (EMI) or radio frequency interference (RFI) that can interfere with the operation of other electronic devices within a certain distance. Without adequate shielding, EMI / RFI interference can cause degradation or complete loss of important signals, rendering the electronic device inefficient or inoperable.

[0006] The term "EMI" as used herein should be taken to include and refer to EMI emissions and RFI emissions generally, and the term "electromagnetic" should be taken to include and refer to electromagnetic frequencies and radio frequencies from both external and internal sources generally. Thus, the term shielding (as used herein) broadly includes and refers to mitigating (or limiting) EMI and / or RFI, such as by absorbing, reflecting, blocking, and / or redirecting the energy or some combination thereof, so that the EMI and / or RFI, for example, no longer interferes with government compliance and / or internal functionality of the electronic component system. SUMMARY

[0007] In one aspect, the present disclosure provides a composite for managing heat and / or electromagnetic interference (EMI), the composite comprising: a matrix; one or more fillers within the matrix; and a phosphonic acid.

[0008] In another aspect, the present disclosure provides an apparatus or system comprising the above-described composite for managing the thermal properties of the apparatus or system. DETAILED DESCRIPTION

[0009] Exemplary embodiments will now be more fully described.

[0010] As recognized herein, thermal interface materials (TIMs) are subject to significant performance requirements, which continue to increase as devices use more power and are further integrated into sensitive electronics or field applications such as automobiles. With the foregoing in mind, exemplary embodiments are developed and / or disclosed herein that include phosphonic acids for the application of enhancing performance in TIMs (broadly, composites) that contribute to properties such as rheology, aging, shelf life, bleed out, and / or adhesion.

[0011] In exemplary embodiments disclosed herein, phosphonic acids are used to enhance the performance of thermal interface materials (TIMs) or other composites for managing heat and / or electromagnetic interference (EMI). In some exemplary embodiments disclosed herein, the phosphonic acid is an additive that is directly added to a formulation for a TIM. In other exemplary embodiments, the TIM includes one or more fillers (e.g., thermally conductive particles, etc.) that are pre-treated with a phosphonic acid, surface modified with a phosphonic acid, and / or coated with a phosphonic acid.

[0012] As an example, a TIM or other composite for managing heat and / or electromagnetic interference (EMI) can include one or more fillers (e.g., thermally conductive particles, etc.) on which one or more thin films, coatings, or layers have been deposited via liquid phase deposition. During the liquid phase deposition process, an organic solvent can be used to facilitate the interaction between the phosphonic acid groups and the surface of the filler particles. An exemplary liquid phase deposition process can include preparing a toluene, alcohol, ester, or hydrocarbon solution containing the phosphonic acid. The mixture is then stirred with the filler particles to be treated. The filler particles are washed with the solvent and the solvent is removed.

[0013] As a further example, TIMs or other composites for the management of heat and / or electromagnetic interference (EMI) can include one or more fillers (e.g., thermally conductive particles, etc.) that are treated by a spray method or other suitable method for depositing the body onto a powder. During the spray method, one or more layers of thin films, coatings, or layers of phosphonic acid can be deposited on the surface of the filler particles. An exemplary method can include preparing a phosphonic acid solution in a suitable solvent and placing the solution and filler particles (e.g., powder, etc.) in a high intensity solid mixer (e.g., double cone mixer with intensifier, etc.).

[0014] TIM resins can include siloxane and / or hydrocarbon polymers, such as a crosslinked siloxane resin system, an uncrosslinked siloxane resin system, an uncrosslinked hydrocarbon resin system, or a crosslinked hydrocarbon resin system. TIMs can also include one or more oils, stabilizers, dispersants, coupling agents, pigments, thixotropic agents, rheology modifiers, tackifiers, and / or solvents. TIMs can also include one or more fillers (e.g., ranging in size from 0.1 pm to 500 pm (D50), etc.), such as aluminum oxide, zinc oxide, aluminum, carbonyl iron, silicon carbide, boron nitride, silver, aluminum nitride, barium titanate, carbon, graphite, other thermally conductive and / or EMI absorbing fillers, combinations thereof, and the like. Among various resin and filler systems, phosphonic acid helps improve rheological properties, aging properties (hardening when exposed to air or high temperatures in high temperature / humidity conditions), shelf life, bleeding, and / or tackiness / adhesion.

[0015] Siloxane generally refers to a compound (e.g., silicone, etc.) having a molecular structure with chains or functional groups based on alternating silicon and oxygen atoms, often with organic groups attached to the silicon atoms. Common siloxanes include silicone, PDMS (polydimethylsiloxane), silicone rubber, silicone oil, liquid silicone, polydimethylsiloxane, and the like.

[0016] Exemplary composites useful for the management of heat and / or electromagnetic interference (EMI) are disclosed. In exemplary embodiments, the composites include a matrix, one or more fillers within the matrix, and a phosphonic acid. For example, the composites can include about 0.01 wt% to about 3 wt% of the phosphonic acid, based on the total weight of the composite, the amount of phosphonic acid being sufficient to enhance the performance of the composite. The phosphonic acid can be an additive added directly to the formulation of the composite, and / or the composite can include one or more fillers pre-treated, surface modified, and / or coated with the phosphonic acid.

[0017] As an example, ToF-SIMS (time-of-flight secondary ion mass spectrometry) can be performed on the full material to identify phosphonic acid species. In uncrosslinked systems, particles can be isolated and analyzed by ToF-SIMS, DRIFTS IR spectroscopy (diffuse reflectance infrared Fourier transform spectroscopy), or XPS (X-ray photoelectron spectroscopy). In crosslinked or uncrosslinked systems, free phosphonic acid in the matrix can be isolated by dissolution or extraction into a solvent, and the extract can be analyzed with UPLC / HPLC-MS, GC-MS, FTIR, or NMR.

[0018] In example embodiments, the phosphonic acid can include octadecyl phosphonic acid, tetradecyl phosphonic acid, and / or dodecyl phosphonic acid. The phosphonic acid can include an organic moiety that is bonded directly to the phosphorus atom through a carbon atom. Preferred phosphonic acids have organic ligands that consist of aliphatic hydrocarbon moieties of about 2-20 carbon atoms. Suitable aliphatic organic ligands can be linear, branched, star-shaped, or cyclic; saturated or unsaturated; and can optionally be substituted with one or more functional groups, including silyl, siloxane, fluoroalkyl, aromatic, thiol, alcohol, carboxylic acid, amine, or amide substituents. Other suitable phosphonic acids can have organic ligands with oligomeric or polymeric structures, having linear, branched, star-shaped, or cyclic structures, including repeating units of polyacrylate, polymethacrylate, polystyrene, polysiloxane, polyester, polyamide, polybutadiene, hydrogenated polybutadiene, polypropylene, polyethylene, or other chemicals. The phosphonic acid can contain one or more phosphonic acid groups.

[0019] In example embodiments, the composite includes at least about 0.05 wt% but no more than about 0.25 wt% of the phosphonic acid. Alternatively, the composite includes at least about 0.1 wt% but no more than about 0.3 wt% of the phosphonic acid. By way of example only, the composite can include about 0.05, 0.1, 0.25, or 0.3 wt% of the phosphonic acid.

[0020] As disclosed herein, the phosphonic acid enhances the performance of the composite as compared to another composite having substantially the same formulation but without the phosphonic acid. For example, the phosphonic acid can enhance the performance of the composite (as compared to another composite having substantially the same formulation but without the phosphonic acid) by one or more of: improving the rheological properties of the composite; improving the aging properties of the composite; improving the shelf life of the composite; improving tack / adhesion; and / or reducing the diffusion of material, if any, that migrates from the composite.

[0021] In example embodiments, the phosphonic acid enhances the performance of the composite (as compared to another composite having substantially the same formulation but without the phosphonic acid) by one or more of: increasing flow rate (grams per minute), increasing time until brittleness (e.g., at 150°C or 200°C, at 85% relative humidity and temperatures of 40°C, 85%, and / or 130°C, etc.), enabling the composite to achieve higher deflection as measured by various tests (e.g., measuring thermal resistance, Shore hardness, bend radius, etc.), enhancing tack as measured via various methods (e.g., peak separation pressure or adhesion, etc.), decreasing minimum bond line thickness at equivalent pressure, decreasing thermal resistance, decreasing modulus of elasticity, and / or any combination of two or more of these performance enhancements.

[0022] In example embodiments, the phosphonic acid enhances the performance of the composite (as compared to another composite having substantially the same formulation but without the phosphonic acid) such that the composite is able to achieve one or more of: higher deflection, enhanced tack as measured via adhesion, and / or decreased minimum bond line thickness (BLT) after two or three weeks of aging at 150°C.

[0023] In example embodiments, the phosphonic acid enhances the performance of the composite (as compared to another composite having substantially the same formulation but without the phosphonic acid) such that the composite is able to achieve one or more of: higher deflection, enhanced tack as measured via adhesion, and / or decreased minimum bond line thickness (BLT) after two or three weeks of aging at 150°C.

[0024] In example embodiments, the composite includes a matrix including a silicone and / or a hydrocarbon polymer. For example, the matrix can include a crosslinked silicone resin system, an uncrosslinked silicone resin system, an uncrosslinked hydrocarbon resin system, or a crosslinked hydrocarbon resin system. The composite can include one or more oils, stabilizers, dispersants, coupling agents, pigments, thixotropic agents, rheology modifiers, tackifiers, and / or solvents.

[0025] In example embodiments, the composite includes thermally conductive particles pre-treated with phosphonic acid, thermally conductive filler particles surface modified with phosphonic acid, and / or thermally conductive filler particles coated with phosphonic acid. The thermally conductive particles can include alumina, zinc oxide, aluminum, and / or other thermally conductive filler particles. As an example, the composite can include zinc oxide particles pre-treated, surface modified, and / or coated with phosphonic acid such that the composite includes about 0.01 wt% phosphonic acid.

[0026] In example embodiments, the composite includes a matrix including a crosslinked silicone resin system. The composite also includes zinc oxide filler and / or alumina filler within the matrix such that the composite includes at least 90 wt% zinc oxide filler and / or alumina filler.

[0027] In example embodiments, the composite includes a matrix including a crosslinked silicone resin system. The composite also includes zinc oxide filler and one or more different alumina fillers within the matrix such that the composite includes at least 90 wt% zinc oxide filler and / or one or more different alumina fillers. The composite also includes at least 0.067 wt% but no more than about 0.2 wt% phosphonic acid.

[0028] In example embodiments, the composite includes a matrix including a crosslinked silicone resin system. The composite also includes one or more different alumina fillers within the matrix such that the composite includes at least 90 wt% one or more different alumina fillers. The composite also includes at least 0.05 wt% but no more than about 0.2 wt% phosphonic acid.

[0029] In example embodiments, the composite includes a matrix including an uncrosslinked silicone resin system. The composite also includes zinc oxide filler and one or more different alumina fillers within the matrix such that the composite includes at least 90 wt% zinc oxide filler and one or more different alumina fillers. The composite also includes at least 0.09 wt% but no more than about 0.25 wt% phosphonic acid.

[0030] In example embodiments, the composite includes a matrix including an uncrosslinked hydrocarbon resin system. The composite also includes zinc oxide filler and one or more different aluminum powders within the matrix such that the composite includes at least 90 wt% zinc oxide filler and one or more different alumina fillers. The composite also includes at least 0.12 wt% but no more than about 0.25 wt% phosphonic acid.

[0031] Example

[0032] The following examples are provided to illustrate the performance enhancements that can be achieved by using the phosphonic acids disclosed herein. Thus, the following examples are provided for illustrative purposes only and not by way of limitation.

[0033] Crosslinked silicone resin system example

[0034] The following Table 1 lists the example formulations in weight percent (wt%) for five test samples containing Control Sample #1 without any phosphonic acid.

[0035]

[0036] Table 1 : Example Formulations with Cross-Linked Silicone Resin System

[0037] The following Table 2 includes test results for five samples. An Instron MTS Criterion, model number 42, equipped with a 1 inch diameter circular platen was used to measure peak separation pressure, minimum bondline, and adhesion (Gic). A 1 inch diameter sample was compressed at a rate of 0.012 mm / min to a force of maximum 450 N. The minimum bondline was the thickness of the sample at 450 N. The maximum deflection scaled the minimum bondline by the initial thickness. After reaching the maximum force, the platen was retracted at 0.012 mm / min. The peak separation pressure was recorded as the maximum force per unit area experienced during this tensile displacement. Adhesion was calculated from the area under the tensile stress-strain curve.

[0038] Table 2: Test Results

[0039]

[0040] Crosslinked silicone resin system example

[0041] Table 3 lists the example formulations in weight percent (wt%) for Control Sample 6 and Sample 7 without any phosphonic acid.

[0042] Table 3: Example Formulations with Cross-Linked Silicone Resin System

[0043] Ingredients Control sample 6 Sample 7 Silicone matrix B (wt%) 6.42％ 6.35％ Catalyst (wt%) 0.005％ 0.004％ Phosphonic acid (wt%) 0％ 0.05％ Ceramic filler B (wt%) 93.58％ 93.6％

[0044] The following Table 4 includes a summary of the physical properties for five test samples 6-10. As shown, formulations containing phosphonic acid with up to 0.1 wt% loading exhibited superior performance compared to samples without phosphonic acid, including higher deflection, enhanced tack (via adhesion measurement), reduced bondline thickness (BLT), and lower elastic modulus.

[0045] Table 4: Summary of Physical Properties

[0046]

[0047] Uncrosslinked silicone resin system example

[0048] Example formulations in weight percent (wt%) are listed in Table 5 below. The preparation procedure for samples 12-16 included adding phosphonic acid, ceramic fillers A and B, and additives (e.g., coupling agents, pigments, thixotropic agents, etc.) to silicone matrix C.

[0049] Table 5: Example Formulations with Uncrosslinked Silicone Resin Systems

[0050] Ingredients Control 11 12 13 14 15 16 Silicone matrix C (wt%) 2.13％ 2.09％ 2.03％ 2.01％ 2.03％ 2.03％ Additive (wt%) 0.42％ 0.42％ 0.42％ 0.42％ 0.42％ 0.42％ Phosphonic acid (wt%) 0％ 0.09％ 0.20％ 0.25％ 0.20％ 0.20％ Ceramic filler A (wt%) 12.58％ 12.58％ 12.58％ 12.58％ 12.58％ 12.58％ Ceramic filler B (wt%) 82.74％ 82.74％ 82.74％ 82.74％ 82.74％ 82.74％

[0051] Samples were prepared and transferred to a 150°C oven under air on an aluminum plate. The samples were then checked at 3 days, 7 days, 10 days, and then weekly. A sample was considered brittle if the material broke or cracked from a metal spatula under light pressure.

[0052] To measure the flow rate of a dispensable TIM material, a Nordson EFP 75cc cartridge was filled with the material, ensuring that no air voids were left behind. The plunger was then placed and pushed down on the material to remove any air pockets. A conical nozzle (0.125” nozzle) was screwed onto the end of the cartridge. The filled cartridge was inserted into a Nordson EFD fluid dispenser assembly. The regulator on the EFD dispenser unit was set to the specified pressure (90 psi) and dispensing time (20 seconds). Prior to starting the flow rate test, some material was dispensed for about 10 seconds to fill the nozzle with material and remove any air pockets. A new aluminum weigh pan (tared) was placed underneath the sample cartridge. After the material was dispensed, the weigh pan was removed with the material and the final weight was recorded. The test was repeated two more times on the remaining material in the cartridge / syringe, for a total of three tests, and the final results were averaged.

[0053] Table 6: Test Results

[0054]

[0055] Uncrosslinked silicone resin system example

[0056] Example formulations in weight percent (wt%) are listed in Table 7 below. The preparation procedure for examples 17-20 included pre-treating phosphonic acid onto ceramic filler A. The pre-treated ceramic filler A, ceramic filler B, and different additives were added to silicone matrix D. Example 17 included the use of octadecyl phosphonic acid. Examples 18 and 19 included the use of dodecyl phosphonic acid. Example 19 included the use of tetradecyl phosphonic acid. Comparative Example 1 (Comp. Ex. 1) included the use of a commercially available propionic acid-surface modified ceramic filler A, while Comparative Example 2 (Comp. Ex. 2) used a lauric acid-surface modified ceramic filler A.

[0057] Table 7: Example Formulations with Uncrosslinked Silicone Resin Systems

[0058]

[0059] The samples were aged the same as when phosphonic acid was added directly to the formulation as described above. Table 8 below includes the test results for the control which did not include ceramic filler A pretreated with phosphonic acid and examples 17, 18, 19, and 20 which included ceramic filler A pretreated with phosphonic acid.

[0060] Table 8 Results for uncrosslinked silicone resin system with ceramic filler A pretreated with phosphonic acid

[0061]

[0062] Uncrosslinked hydrocarbon resin system example

[0063] Table 9 includes the example formulations with uncrosslinked hydrocarbon resin systems. Samples were prepared with a target thickness of 200 pm for testing.

[0064] Table 9: Example formulations with uncrosslinked hydrocarbon resin systems

[0065]

[0066] Samples were prepared between liners and placed in a humidity chamber at 85 °C and 85% relative humidity for 48 hours. The properties after aging (thermal resistance, minimum bond line) were measured on a TIMA 5 instrument at 70 °C, the results of which are in Table 10 below.

[0067] Table 10 Results for uncrosslinked hydrocarbon resin systems

[0068]

[0069] As shown in Table 10, the formulations containing phosphonic acid exhibited superior properties with reduced thermal resistance and minimum bond line thickness after aging at high temperature and humidity compared to the formulation without phosphonic acid.

[0070] In example embodiments, the thermal interface material includes a composite as disclosed herein. The thermal interface material includes a thermal pad, a thermal gap filler, a phase change thermal interface material, a dispensable material, a bulk putty, a thermal grease, a thermal interface material sheet, a thermal transport layer in an optical module, etc. For example, the thermal interface material can include a thermal pad having a rectangular, triangular, circular, oval, polygonal, etc. shape. The thermal interface material can include a sheet having a rectangular, triangular, circular, oval, polygonal, etc. shape. The thermal interface material can include a die cut portion having a rectangular, triangular, circular, oval, polygonal, etc. shape.

[0071] In example embodiments, the composite includes one or more fillers including one or more of: thermally conductive fillers; electrically conductive fillers; electromagnetic wave absorbing fillers; dielectric fillers; and fillers having two or more properties of thermally conductive, electrically conductive, dielectric, and electromagnetic wave absorbing. In example embodiments, the composite includes one or more fillers including one or more of aluminum oxide, zinc oxide, aluminum, carbonyl iron, silicon carbide, boron nitride, silver, aluminum nitride, barium titanate, carbon, graphite, other typical thermally conductive and / or EMI absorbing fillers, combinations thereof, and the like. Also, the one or more fillers can have a D 50 median particle size in a range of about 0.1 microns to about 500 microns.

[0072] In example embodiments, the composite includes thermally conductive fillers and EMI absorbing fillers in the matrix such that the composite includes a multifunctional EMI absorber having a first function of EMI mitigation and a second function of thermal management, or vice versa. By way of example, the fillers can include one or more of functional nanoparticles, electrically conductive fillers, thermally conductive fillers, EMI or microwave absorbing fillers, magnetic fillers, coated fillers, combinations thereof, and the like. The fillers can be added and mixed into a bulk material including a matrix material, thereby providing a mixture of the fillers and the base or matrix material. Example fillers include carbon black, boron nitride, nickel cobalt, carbonyl iron, siliconized iron, iron particles, iron chromium compounds, silver, an alloy containing 85% iron, 9.5% silicon, and 5.5% aluminum, an alloy containing about 20% iron and 80% nickel, ferrites, magnetic alloys, magnetic powders, magnetic flakes, magnetic particles, nickel-based alloys and powders, chromium alloys, oxides, copper, zinc oxide, aluminum oxide, graphite, ceramics, silicon carbide, manganese zinc, glass fibers, carbon nanotubes (e.g., single wall carbon nanotubes, multiwall carbon nanotubes, and / or carbon nanostructures, etc.), combinations thereof, and the like. The fillers can include one or more of particles, spheroids, microspheres, ellipsoids, irregular spheroids, strands, flakes, powders, nanotubes, and / or combinations of any or all of these shapes. Further, example embodiments can also include different grades (e.g., different sizes, different purities, different shapes, etc.) of the same (or different) fillers.

[0073] In exemplary embodiments, the composite has a high thermal conductivity of at least 1 Watt per meter / Kelvin (W / mK), as determined by a hot disk thermal constant analyzer. For example, the composite can have a thermal conductivity of 1 W / mK, 2 W / mK, 3 W / mK, 4 W / mK, 5 W / mK, greater than 5 W / mK, etc. To determine the thermal conductivity, a hot disk instrument can be used, which measures thermal conductivity, thermal diffusivity, and specific heat capacity using the transient plane source method. As background, this technique is covered under ISO 22007-2:2008; Part 2 standard. The technique utilizes a planar sensor and a special mathematical model describing the thermal conductivity, combined with electronics that makes the method possible to use for measuring thermal transport properties. Its coverage is for thermal conductivity range of 0.01-500 W / m / K. The transient plane source technique typically employs two sample halves that sandwich the sensor in between. The method can also be used in a single-sided configuration. The technique is versatile and fast, covering measurements of solids, pastes, thin films, and liquids. The technique can test isotropic and anisotropic materials. The flat sensor consists of a continuous double spiral of conductive nickel metal etched out of a thin foil. The nickel spiral is located between two thin polyimide films, Kapton. During the measurement, a constant electrical effect is passed through the conductive spiral, thereby increasing the sensor temperature. The generated heat dissipates into the sample on both sides of the sensor at a rate that depends on the thermal transport properties of the material. By recording the temperature response in the sensor versus time, the thermal conductivity, thermal diffusivity, and specific heat capacity of the material can be calculated.

[0074] In exemplary embodiments, the device or system includes a composite as disclosed herein for managing thermal properties of the device or system.

[0075] Also disclosed are exemplary methods of using phosphonic acids to enhance the performance of composites for managing heat and / or electromagnetic interference (EMI). In exemplary embodiments, the method includes including from about 0.01 weight percent to about 3 weight percent of a phosphonic acid in the composite, based on the total weight of the composite, in an amount sufficient to enhance the performance of the composite (as compared to another composite having substantially the same formulation but without the phosphonic acid). The method can include pre-treating, surface modifying, and / or coating one or more fillers with the phosphonic acid. Additionally or alternatively, the method can include adding the phosphonic acid as an additive to the composite formulation. The composite can include thermal management and / or electromagnetic interference (EMI) mitigating materials, such as thermal interface materials (TIMs), EMI absorber materials, thermally conductive EMI absorber materials, electrically conductive materials, combinations thereof, etc.

[0076] In example methods, the phosphonic acid can include an organic moiety bonded directly to the phosphorus atom through a carbon atom. Preferred phosphonic acids have organic ligands consisting of aliphatic hydrocarbon moieties of about 2-20 carbon atoms. Suitable aliphatic organic ligands can be linear, branched, star-shaped, or cyclic; saturated or unsaturated; and can be optionally substituted with one or more functional groups, including silyl, siloxane, fluoroalkyl, aromatic, thiol, alcohol, carboxylic acid, amine, or amide substituents. Other suitable phosphonic acids can have organic ligands having oligomeric or polymeric structures, having linear, branched, star-shaped, or cyclic structures, comprising repeating units of polyacrylate, polymethacrylate, polystyrene, polysiloxane, polyester, polyamide, polybutadiene, hydrogenated polybutadiene, polypropylene, polyethylene, or other chemicals. The phosphonic acid can contain one or more phosphonic acid groups. The phosphonic acid can include one or more of octadecyl phosphonic acid, tetradecyl phosphonic acid, and / or dodecyl phosphonic acid.

[0077] In example methods, the use of the phosphonic acid enhances the performance of the compound (as compared to another compound having substantially the same formulation but without the phosphonic acid) by one or more of: improving the rheological properties of the compound; improving the aging properties of the compound; improving the shelf life of the compound; improving tack / adhesion; and / or reducing the diffusion of material (if any) migrating from the compound.

[0078] In example implementations, an electronic device includes a heat source and a compound as disclosed herein, which can be used as a thermal interface material (e.g., a thermal pad, a thermal gap filler, a phase change thermal interface material, a dispensable material, a bulk grease, a thermal grease, a thermal interface material sheet, a heat transport layer in an optical module, etc.). The compound is positioned relative to the heat source for establishing at least a portion of a thermally conductive heat path from the heat source through the compound. The compound can also be configured to be EMI-absorbing and / or electrically conductive, such that the compound is also operable to mitigate and / or manage EMI within the electronic device.

[0079] In example implementations, an electronic device includes a heat source, a heat removal / dissipation structure, and a compound as disclosed herein, which can be used as a thermal interface material (e.g., a thermal pad, a thermal gap filler, a phase change thermal interface material, a dispensable material, a bulk grease, a thermal grease, a thermal interface material sheet, a heat transport layer in an optical module, etc.). The compound is positioned relative to the heat source and the heat removal / dissipation structure for establishing at least a portion of a thermally conductive heat path between the heat source and the heat removal / dissipation structure. The compound can also be configured to be EMI-absorbing and / or electrically conductive, such that the compound is also operable to mitigate and / or manage EMI within the electronic device.

[0080] In example embodiments, an electronic device includes a heat source, a board-level shield, and a composite as disclosed herein that can be used as a thermal interface material (e.g., a thermal pad, a thermal gap filler, a phase change thermal interface material, a dispensable material, a bulk grease, a thermal grease, a thermal interface material sheet, a thermal transport layer in an optical module, etc.). The composite is positioned relative to the heat source and the board-level shield for establishing at least a portion of a thermally conductive thermal path between the heat source and the board-level shield. The composite can also be configured to be EMI absorbing and / or electrically conductive such that the composite is further operable to mitigate and / or manage EMI within the electronic device.

[0081] In example embodiments, an electronic device includes a heat source, a board-level shield, a heat removal / dissipation structure, and first and second composites that can be used as a thermal interface material (e.g., a thermal pad, a thermal gap filler, a phase change thermal interface material, a dispensable material, a bulk grease, a thermal grease, a thermal interface material sheet, a thermal transport layer in an optical module, etc.). The first composite is positioned relative to the heat source and the board-level shield for establishing at least a portion of a first thermally conductive thermal path between the heat source and the board-level shield. The second composite is positioned relative to the board-level shield and the heat removal / dissipation structure for establishing at least a portion of a second thermally conductive thermal path between the board-level shield and the heat removal / dissipation structure. The first and / or second composites can also be configured to be EMI absorbing and / or electrically conductive such that the first and / or second composites are further operable to mitigate and / or manage EMI within the electronic device.

[0082] In example embodiments, an electronic device includes an integrated circuit, a board-level shield, a heat sink, and first and second composites that can be used as a thermal interface material (e.g., a thermal pad, a thermal gap filler, a phase change thermal interface material, a dispensable material, a bulk grease, a thermal grease, a thermal interface material sheet, a thermal transport layer in an optical module, etc.). The first composite is positioned relative to the integrated circuit and the board-level shield for establishing at least a portion of a first thermally conductive thermal path between the integrated circuit and the board-level shield. The second composite is positioned relative to the board-level shield and the heat sink for establishing at least a portion of a second thermally conductive thermal path between the board-level shield and the heat sink. The first and / or second composites can also be configured to be EMI absorbing and / or electrically conductive such that the first and / or second composites are further operable to mitigate and / or manage EMI within the electronic device.

[0083] The example implementations disclosed herein can be used in a wide range of industries (e.g., automotive, consumer, industrial, data communications / telecommunications, aerospace / defense, etc.) and a wide range of applications (e.g., automotive electronics, automotive advanced driver assistance systems (ADAS), automotive powertrain / electronic control units (ECUs), automotive infotainment, routers, hard drives, solid state drives, wireless infrastructure, drones / satellites, gaming systems, smart home devices, laptops / tablets / portable devices, etc.). Moreover, the example implementations disclosed herein can be used in a wide range of: various heat sources, electronic devices, and / or heat removal / dissipation structures or components (e.g., heat sinks, heat spreaders, heat pipes, vapor chambers, device housings, enclosures, or chassis, etc.). For example, the heat sources can include one or more heat-generating components or devices, such as high power integrated circuits (ICs), optical transceivers, 5G infrastructure equipment (e.g., base stations, small cells, smart poles, etc.), solid state drives (SSDs), memory in video cards, set-top boxes, televisions, gaming systems, automotive electronics for autonomous driving (ADAS) (e.g., radar, multi-domain controllers, cameras, etc.), CPUs, dies within underfill, semiconductor devices, flip-chip devices, graphics processing units (GPUs), digital signal processors (DSPs), multi-processor systems, integrated circuits (ICs), multi-core processors, etc.). In general, the heat sources can include any component or device that has a higher temperature than the heat management and / or EMI mitigation material or otherwise provides or transfers heat to the heat management and / or EMI mitigation material, whether the heat is generated by the heat source or merely transferred through or via the heat source. Accordingly, aspects of the present disclosure should not be limited to use with any single type of heat source, electronic device, heat removal / dissipation structure, etc.

[0084] The example implementations are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of implementations of the present disclosure. Those skilled in the art will recognize that the example implementations can be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In some example implementations, well-known processes, well-known device structures, and well-known technologies are not described in detail unless their function is more relevant to the presently disclosed example implementations. Furthermore, advantages and improvements that can accrue from the one or more example implementations disclosed herein are provided for illustrative purposes only and do not limit the scope of the present disclosure (as the example implementations disclosed herein can provide all or none of the advantages and improvements described, and still fall within the scope of the present disclosure).

[0085] The particular dimensions, materials, and / or specific shapes disclosed herein are by way of example only and without limitation. The disclosure of specific values and particular values ranges for given parameters herein is not to be construed as limiting on other values and value ranges that can be used in one or more of the examples disclosed herein. Moreover, it is contemplated that any two specific values for a particular parameter recited herein can define the endpoints for a range of values for the given parameter (i.e., the disclosure of a first value and a second value for a given parameter can be interpreted as disclosing that any value between the first and second values, including the first and second values themselves, can also be employed for the given parameter). For example, if a parameter X is exemplified herein as having a value of A and also as having a value of Z, it is contemplated that parameter X can have a range of values from about A to about Z. Similarly, it is contemplated that the disclosure of two or more value ranges for a parameter, whether such ranges are nested, overlapping, or distinct, includes all possible combinations of the ranges with the endpoints of the ranges used as the limits of each range. For example, if parameter X is exemplified herein as having a value in a range of 1-10 or 2-9 or 3-8, it is also contemplated that parameter X can have other value ranges including 1-9, 1-8, 1-3, 1-2, 2-10, 2-8, 2-3, 3-10, and 3-9.

[0086] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. For example, use of terms such as "may contain," "may include," and the like, indicates that at least one embodiment includes the feature. As used herein, the singular forms "a" and "an" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises" and "comprising" are inclusive, and therefore specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order

[0087] When an element or layer is referred to as being "on", "engaged", "connected", or "coupled" to another element or layer, it can be directly on, engaged, connected, or coupled to the other element or layer, or intervening elements or layers can be present. In contrast, when an element is referred to as being "directly on", "directly engaged", "directly connected", or "directly coupled" to another element or layer, there are no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in the same way (e.g., "between" versus "directly between", "adjacent" versus "directly adjacent", etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0088] The term "about" when applied to a value indicates that the calculation or measurement is permitted to vary slightly from the value (close to the accurate; nearly or reasonably close to the value; nearly). If the inaccuracy provided by "about" is not otherwise understood in the art for some reason, "about" as used herein indicates at least variation that can be caused by ordinary measurement methods or use of such parameters. For example, the terms "substantially", "approximately", and "about" can be used herein to mean within manufacturing tolerances. Whether or not modified by the term "about", the claims include equivalents of the recited numbers.

[0089] Although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first", "second", and other numerical terms as used herein do not permit order, unless the context clearly indicates. Thus, elements, components, regions, layers or sections discussed below as first elements, components, regions, layers or sections can be called second elements, components, regions, layers or sections without deviating from the teachings of the example embodiments.

[0090] Spatially relative terms such as "in", "on", "engaged", "connected", or "coupled" and the like, as used herein, can be used to describe one element or feature's relationship to another element or feature as it is oriented in use or operation. Spatially relative terms can be intended to encompass different orientations of the device in use or operation. For example, if a device is turned over, an element described as "below" or "beneath" another element or feature would then be oriented "above" the other element or feature. Thus, the example term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0091] The foregoing description of implementations has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Independent elements, intended or stated uses, or features of a specific implementation are generally not limited to that particular implementation, but rather, are interchangeable with other implementations, as appropriate, and as would be understood by those in the art to which the disclosure pertains. The same can hold true for the description of features or aspects within subsequent sections. Such changes do not depart from the spirit of the disclosure. The scope of the disclosure is therefore intended to be only in accordance with the appended claims, rather than the description and its associated drawings.

Claims

1. A composite for managing thermal and / or electromagnetic interference (EMI), the composite comprising: Matrix; One or more fillers within the matrix; and Phosphonic acid.

2. The complex according to claim 1, wherein, The one or more fillers are pretreated with the phosphonic acid, surface modified with the phosphonic acid, and / or coated with the phosphonic acid.

3. The complex according to claim 1, wherein, The phosphonic acid is an additive that is directly added to the formulation of the complex.

4. The complex according to claim 1, wherein, The one or more fillers are pretreated, surface modified and / or coated with the phosphonic acid, such that the composite contains about 0.01% by weight to about 3% by weight of the phosphonic acid based on the total weight of the composite.

5. The complex according to claim 1, wherein, The complex contains about 0.01% by weight to about 3% by weight of phosphonic acid based on the total weight of the complex.

6. The complex according to claim 1, wherein: The phosphonic acid includes an organic moiety that is directly bonded to a phosphorus atom via a carbon atom; and / or The phosphonic acid comprises an aliphatic organic ligand having an aliphatic hydrocarbon moiety having about 2 to 20 carbon atoms, wherein the aliphatic organic ligand may be linear, branched, star-shaped or cyclic and / or saturated or unsaturated.

7. The complex according to claim 1, wherein: The phosphonic acid has an organic ligand comprising an oligomeric or polymeric structure, has a linear, branched, star-shaped, or cyclic structure, and comprises repeating units of polyacrylate, polymethacrylate, polystyrene, polysiloxane, polyester, polyamide, polybutadiene, hydrogenated polybutadiene, polypropylene, polyethylene, or other chemicals; and / or The phosphonic acid includes one or more phosphonic acid groups.

8. The complex according to claim 1, wherein, The phosphonic acid includes one or more of the following: Octadecylphosphonic acid; Tetradecylphosphonic acid; and / or Dodecylphosphonic acid.

9. The complex according to claim 1, wherein, The complex includes: At least about 0.05% by weight but not more than about 0.25% by weight of the phosphonic acid; or At least about 0.1% by weight but not more than about 0.3% by weight of the phosphonic acid.

10. The complex according to any one of claims 1 to 9, wherein, Compared to another complex with essentially the same formulation but without the phosphonic acid, the phosphonic acid enhances the performance of the complex by one or more of the following: Improve the rheological properties of the composite; Improve the aging properties of the composite; To improve the shelf life of the complex; Improve tack / adhesion; and / or In the presence of material migrating from the complex, the diffusion of the material migrating from the complex is reduced.

11. The complex according to any one of claims 1 to 9, wherein, Compared to another complex with essentially the same formulation but without the phosphonic acid, the phosphonic acid increases the flow rate (g / min) of the complex.

12. The complex according to any one of claims 1 to 9, wherein, Under one or more of the following conditions, compared to another complex having substantially the same formulation but without the phosphonic acid, the time it takes for the phosphonic acid to increase until brittleness is achieved: 150℃ or 200℃; 85% relative humidity and 40°C; 85% relative humidity and 85°C temperature; and / or 85% relative humidity and 130℃ temperature; Therefore, the time until brittleness can be determined by measuring one or more of thermal resistance, Shore hardness, and / or bending radius.

13. The complex according to any one of claims 1 to 9, wherein, Compared to another complex with essentially the same formulation but without the phosphonic acid, the phosphonic acid enables the complex to achieve greater flexibility.

14. The complex according to any one of claims 1 to 9, wherein, Compared to another complex with essentially the same formulation but without the phosphonic acid, the phosphonic acid enhances viscosity, thereby allowing the viscosity to be determined by measuring the peak separation pressure and / or adhesion of the complex.

15. The complex according to any one of claims 1 to 9, wherein, Under equivalent pressure, compared to another composite with substantially the same formulation but without the phosphonic acid, the phosphonic acid reduces the minimum bond line thickness (BLT) of the composite.

16. The complex according to any one of claims 1 to 9, wherein, The phosphonic acid reduces the thermal resistance of the complex having a substantially identical formulation but without the phosphonic acid.

17. The complex according to any one of claims 1 to 9, wherein, Compared to another complex with essentially the same formulation but without the phosphonic acid, the phosphonic acid reduces the elastic modulus of the complex.

18. The complex according to any one of claims 1 to 9, wherein, The one or more fillers include one or more of the following: Thermally conductive filler; Conductive filler; Electromagnetic wave absorbing filler; Dielectric fillers; and Fillers that possess two or more of the following properties: thermal conductivity, electrical conductivity, dielectric properties, and electromagnetic wave absorption.

19. The complex according to any one of claims 1 to 9, wherein: The one or more fillers include one or more of alumina, zinc oxide, aluminum, iron carbonyl, silicon carbide, boron nitride, silver, aluminum nitride, barium titanate, carbon, and graphite; and / or D of the one or more fillers 50 The median particle size is approximately 0.1 micrometers to approximately 500 micrometers.

20. The complex according to any one of claims 1 to 9, wherein, The matrix includes polymer-based resin systems, such as cross-linked siloxane resin systems, uncross-linked siloxane resin systems, uncross-linked hydrocarbon resin systems, or cross-linked hydrocarbon resin systems.

21. The complex according to any one of claims 1 to 9, wherein, The one or more fillers include thermally conductive particles, which include one or more of alumina, zinc oxide and / or aluminum, and the thermally conductive particles are pretreated with the phosphonic acid, surface modified with the phosphonic acid, and / or coated with the phosphonic acid.

22. The complex according to any one of claims 1 to 9, wherein: The matrix comprises a cross-linked siloxane resin system; and The one or more fillers include zinc oxide filler and / or alumina filler in the matrix, such that the composite comprises at least 90% by weight of the zinc oxide filler and / or the alumina filler.

23. The complex according to any one of claims 1 to 9, wherein: The composite material is a thermal interface material, an EMI absorber material, a thermally conductive absorbing material, a conductive material, or a combination of two or more thereof; and / or The composite is a thermal phase change material, thermal putty, thermal grease, dispensable thermal interface material and / or thermal gap filler.

24. An apparatus or system comprising the complex of any one of claims 1 to 9 for managing the thermal properties of said apparatus or system.

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