Thermally conductive electromagnetic interference (EMI) absorber

Abstract

To disclose a thermally conductive electromagnetic interference (EMI) absorber.SOLUTION: A thermally conductive electromagnetic interference (EMI) absorber 100 includes a matrix and at least one functional filler in the matrix. The at least one functional filler includes stainless steel. The thermally conductive EMI absorber 100 can have an attenuation in the range of about 1 decibel per centimeter to about 15 decibels per centimeter at frequencies in the range of 1 megahertz to 2 gigahertz.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to thermally conductive EMI absorbers. [Background technology]

[0002] This section provides background information related to the present disclosure that is not necessarily prior art. Electrical components, such as semiconductors, integrated circuit packages, transistors, and the like, typically have a pre-designed temperature at which they optimally operate. Ideally, the pre-designed temperature is close to the temperature of the surrounding air. However, operation of the electrical components generates heat. If the heat is not removed, the electrical components may operate at temperatures significantly higher than their normal or desired operating temperature. Such excessive temperatures can adversely affect the operating characteristics of the electrical components and the operation of associated devices.

[0003] To avoid or at least mitigate adverse operating characteristics due to heat generation, heat must be removed, for example, by transferring heat from an operating electrical component 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 an operating electrical component to a heat sink by direct surface contact between the electrical component and the heat sink and / or by contact between the electrical component and the heat sink surface through an intermediate medium or thermal interface material (TIM). Thermal interface materials can be used to fill gaps between heat transfer surfaces to increase heat transfer efficiency compared to filling the gap with air, which has a relatively low thermal conductivity.

[0004] Additionally, a common problem in the operation of electronic devices is the generation of electromagnetic radiation within the equipment's electronic circuits. Such radiation can cause electromagnetic interference (EMI) or radio frequency interference (RFI), which can disrupt the operation of other electronic devices within a certain proximity. Without proper shielding, EMI / RFI interference can cause degradation or complete loss of important signals, thereby rendering electronic equipment inefficient or inoperable.

[0005] A common solution to ameliorating the effects of EMI / RFI is to use shields that absorb and / or reflect and / or redirect EMI energy. These shields are typically used to localize the EMI / RFI within its source and to isolate other devices that are near the EMI / RFI source.

[0006] The term "EMI," as used herein, should generally be considered to include and refer to EMI and RFI emissions, and the term "electromagnetic" should generally be considered to include and refer to electromagnetic and radio frequencies from external and internal sources. Accordingly, the term shielding (as used herein) broadly includes and refers to reducing (or limiting) EMI and / or RFI so that it does not interfere, such as by attenuating, absorbing, reflecting, blocking, and / or redirecting energy, or some combination thereof, for example, for government compliance and / or the internal functioning of an electronic system. [Brief explanation of the drawings]

[0007] The drawings described herein are for purposes of illustrating selected embodiments only, not all possible embodiments, and are not intended to limit the scope of the present disclosure. [Figure 1] 1 shows an exemplary embodiment of a thermally conductive EMI absorber disposed between a board-level shield and an integrated circuit or chip. FIG. 1 also shows a conventional thermal pad disposed between a heat sink and a board-level shield. [Figure 2] 1 is a line graph of attenuation in decibels per centimeter (dB / cm) versus frequency in gigahertz (GHz) for a thermally conductive EMI absorber of an exemplary embodiment. [Figure 3]1 is a line graph of percent deflection (%) versus pressure in kilopascals (kPa) for an exemplary embodiment thermally conductive EMI absorber, where the thermally conductive EMI absorber had a starting thickness of 1 millimeter (mm). [Figure 4] 1 is a line graph of thermal resistance in Celsius temperature units per square centimeter per watt (C*cm / W) versus pressure (kPa) for an example embodiment thermally conductive EMI absorber, where the thermally conductive EMI absorber had a starting thickness of 1 mm. [Figure 5] 1 is a line graph of decibel attenuation (dB / cm) versus frequency (GHz) for a thermally conductive EMI absorber of an exemplary embodiment. [Figure 6] 1 is a line graph of thermal resistance (C*cm2 / W) versus pressure in pounds per square inch (psi) at 50° C. according to ASTM D5470 for a thermally conductive EMI absorber of an exemplary embodiment. [Figure 7] 1 is a line graph of percent deflection (%) versus pressure (psi) for a thermally conductive EMI absorber of an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Detailed Description Exemplary embodiments will now be described more fully with reference to the accompanying drawings. As recognized herein, in applications where both heat and stray radiation are a concern, there is a need for a material that has high thermal conductivity and efficiently absorbs microwaves, allowing the use of a single material rather than two separate materials. For example, it is not uncommon to use two different interface materials for different functions within an application, one optimized for thermal conduction properties and the other optimized for absorption properties. It is also recognized herein that higher thermal conductivities (e.g., greater than 6 W / mK) are required to meet increasing heat dissipation demands without sacrificing absorption properties.

[0009] Accordingly, disclosed herein are exemplary embodiments of thermally conductive electromagnetic interference (EMI) absorbers having a thermal conductivity of greater than 6 W / mK (e.g., at least about 7.5 W / mK, at least about 11 W / mK, at least about 11.5 W / mK, at least about 12 W / mK, etc.) and attenuation such as greater than 15 decibels per centimeter (dB / cm) at frequencies of 10 gigahertz (GHz) or greater. In some exemplary embodiments, the thermally conductive EMI absorbers have a thermal conductivity of at least about 5 W / mK (e.g., 5 W / mK, 6 W / mK, 7.5 W / mK, greater than 6 W / mK, at least about 7.5 W / mK, at least about 11 W / mK, at least about 11.5 W / mK, at least about 12 W / mK, etc.) and attenuation in a range of about 1 dB / cm to about 15 dB / cm at frequencies in a range such as 1 MHz to 2 GHz. Accordingly, disclosed herein are exemplary embodiments of thermally conductive EMI absorbers that have both high thermal conductivity and efficient absorption, and that can be used as a single interface material. The thermally conductive EMI absorber is configured to have the combined performance of a thermal interface material and an EMI absorber.

[0010] Thus, the thermally conductive EMI absorbers disclosed herein can be used to establish a thermally conductive heat path having a high thermal conductivity (e.g., at least 5 W / mK, at least 11 W / mK, etc.) between a heat source (e.g., an integrated circuit, etc.) and a heat dissipation / removal structure (e.g., a board-level shield, a heat sink, etc.) while also suppressing radiated electromagnetic fields (e.g., coupling between an integrated circuit and a heat sink, etc.).

[0011] For example, FIG. 1 illustrates an exemplary embodiment of a thermally conductive EMI absorber 100 disposed between a board-level shield 104 and an integrated circuit or chip 108. FIG. 1 also illustrates a conventional thermal interface material 112 disposed between a heat sink 116 and the board-level shield 104. In the illustrated embodiment of FIG. 1, the thermally conductive EMI absorber 100 is operable as a thermal interface material to establish a thermally conductive heat path from the integrated circuit 108 to the board-level shield 104. The thermally conductive EMI absorber 100 is also operable as an EMI absorber to suppress coupling of radiated electromagnetic fields between the integrated circuit 108 and the heat sink 116. Thus, the thermally conductive EMI absorber 100 may provide a dual-purpose, space-saving, single product that combines the performance of a thermal interface material and an EMI absorber.

[0012] In an exemplary embodiment, the thermally conductive EMI absorber has a thermal conductivity of at least 6 W / mK (e.g., at least about 7.5 W / mK, at least about 11 W / mK, at least about 11.5 W / mK, at least about 12 W / mK, etc.), an attenuation of greater than 15 dB / cm at frequencies equal to or greater than 10 GHz (e.g., at least about 20 dB / cm at frequencies equal to or greater than 10 GHz), an attenuation of greater than 34 dB / cm at frequencies equal to or greater than 20 GHz, an attenuation of greater than 66 dB / cm at frequencies equal to or greater than 40 GHz, and an attenuation of greater than 90 dB / cm at frequencies equal to or greater than 60 GHz. Continuing with this example, the thermally conductive EMI absorber may include a silicone-free gap filler pad initially provided in a sheet form (e.g., an 18-inch by 18-inch sheet) having a sheet thickness in the range of 0.5 mm to 5 mm. The thermally conductive EMI absorber may be disposed between release liners as a sheet or as a die-cut part. Alternatively, the thermally conductive EMI absorber may be configured differently (e.g., have a different matrix system), such as having a phase change, grease, putty, or other non-pad form. The thermally conductive EMI absorber may have one or more of the properties shown in Table 1 and / or Table 2 below.

[0013] In an exemplary embodiment, the thermally conductive EMI absorber comprises a matrix and at least one functional filler in the matrix. The thermally conductive EMI absorber has a thermal conductivity greater than 6 W / mK and an attenuation greater than 15 decibels per centimeter (dB / cm) at frequencies equal to or greater than 10 gigahertz (GHz). In another exemplary embodiment, the thermally conductive EMI absorber has a thermal conductivity of at least about 5 W / mK and an attenuation in the range of about 1 dB / cm to about 15 dB / cm at frequencies in the range of 1 MHz to 2 GHz.

[0014] In some exemplary embodiments, the thermally conductive EMI absorber has a thermal conductivity of at least 11 W / mK (e.g., 11 W / mK, 11.5 W / mK, 12 W / mK, etc.), and has an attenuation of greater than 15 dB / cm at frequencies equal to or greater than 10 GHz, an attenuation of greater than 34 dB / cm at frequencies equal to or greater than 20 GHz, an attenuation of greater than 66 dB / cm at frequencies equal to or greater than 40 GHz, and / or an attenuation of greater than 90 dB / cm at frequencies equal to or greater than 60 GHz.

[0015] In some exemplary embodiments, the matrix comprises a thermoreversible oil gel, which includes a process oil (such as paraffin oil) and a block copolymer. The block copolymer may include a diblock copolymer (such as a diblock styrene copolymer) and / or a triblock copolymer (such as a triblock styrene copolymer).

[0016] In some exemplary embodiments, the process oil and block copolymer are not chemically crosslinked, such that the thermally conductive EMI absorber is a thermoreversible thermoplastic material. For example, the matrix may include a thermoplastic silicone-free polymeric oil gel resin.

[0017] In some exemplary embodiments, the matrix comprises a non-silicone polymer matrix, such as a non-silicone oil gel resin. The non-silicone polymer matrix may comprise a styrene and ethylene / butylene copolymer and / or a styrene and ethylene / propylene copolymer. The thermally conductive EMI absorber may be configured as a non-silicone gap filler pad, putty, grease, or silicone-free phase change material. In an alternative embodiment, the thermally conductive EMI absorber comprises a silicone-based matrix system.

[0018] In some exemplary embodiments, the matrix includes a paraffinic processing oil, a styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and a coupling agent. In alternative exemplary embodiments, the matrix may include a styrene-ethylene-butylene-styrene (SEBS) linear polymer having a triblock structure in addition to or instead of the styrene-ethylene-propylene (SEP) linear polymer having a diblock structure.

[0019] In some exemplary embodiments, the at least one functional filler in the matrix comprises one or more of zinc oxide, silicon carbide, carbonyl iron, aluminum oxide, aluminum nitride, aluminum, boron nitride, silicon nitride, iron, graphite, ferrite, alumina trihydrate, silica, stainless steel, iron silicide, manganese zinc-based ferrite, nickel zinc-based ferrite, and / or magnetic metal powder. The thermally conductive EMI absorber may comprise at least 90% by weight of the at least one functional filler and 10% by weight or less of the matrix. The thermally conductive EMI absorber may comprise at least 70% by volume (e.g., at least 80% by volume) of the at least one functional filler and 30% by volume or less (e.g., 20% by volume or less) of the matrix. The at least one functional filler may comprise different grades (e.g., different sizes, different purities, different shapes, etc.) of the same (or different) functional filler. For example, the thermally conductive EMI absorber may include two or more (e.g., four, five, etc.) different grades (e.g., sizes, etc.) of silicon carbide. Other suitable fillers and / or additives, such as pigments, plasticizers, processing aids, flame retardants, extenders, tackifiers, antioxidants, ultraviolet (UV) stabilizers, may also be added to the thermally conductive EMI absorber.

[0020] In some exemplary embodiments, the at least one functional filler includes (e.g., consists of) carbonyl iron, silicon carbide, zinc oxide, aluminum nitride, and aluminum oxide. The matrix also includes (e.g., consists of) paraffinic processing oil, a styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and a coupling agent. The matrix also, or alternatively, includes a styrene-ethylene-butylene-styrene (SEBS) linear polymer having a triblock structure. In these exemplary embodiments, the thermally conductive EMI absorber includes at least 90% by weight of at least one functional filler (carbonyl iron, silicon carbide, zinc oxide, aluminum nitride, and aluminum oxide) and 10% by weight or less of the matrix. The thermally conductive EMI absorber includes at least 80% by volume of at least one functional filler (carbonyl iron, silicon carbide, zinc oxide, aluminum nitride, and aluminum oxide) and 20% by volume or less of the matrix.

[0021] In other exemplary embodiments, the at least one functional filler includes (e.g., consists of) zinc oxide, silicon carbide, and aluminum nitride. The matrix also includes (e.g., consists of) paraffinic processing oil, a styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and a coupling agent. The matrix also, or alternatively, includes a styrene-ethylene-butylene-styrene (SEBS) linear polymer having a triblock structure. In these other exemplary embodiments, the thermally conductive EMI absorber includes at least 90% by weight of at least one functional filler (zinc oxide, silicon carbide, and aluminum nitride) and 10% by weight or less of the matrix. The thermally conductive EMI absorber includes at least 80% by volume of at least one functional filler (zinc oxide, silicon carbide, and aluminum nitride) and 20% by volume or less of the matrix.

[0022] In further exemplary embodiments, the at least one functional filler includes (e.g., consists of) aluminum oxide and silicon carbide. The matrix also includes (e.g., consists of) a process oil, a diblock polymer, a coupling agent, an antioxidant, and silica. The matrix also, or alternatively, includes a triblock polymer. In these further exemplary embodiments, the thermally conductive EMI absorber includes at least 90% by weight of the at least one functional filler (aluminum oxide and silicon carbide) and 10% by weight or less of the matrix. The thermally conductive EMI absorber includes at least 80% by volume of the at least one functional filler (aluminum oxide and silicon carbide) and 20% by volume or less of the matrix.

[0023] In some exemplary embodiments, the thermally conductive EMI absorber may have a hardness of about 68 Shore 00 or less at 3 seconds and about 55 Shore 00 or less at 30 seconds. By way of example, the thermally conductive EMI absorber may have a hardness of about 58 Shore 00 at 3 seconds and about 37 Shore 00 or less at 30 seconds. Alternatively, for example, the thermally conductive EMI absorber may have a hardness of about 58 Shore 00 at 3 seconds and about 31 Shore 00 or less at 30 seconds. The thermally conductive EMI absorber is dielectric and not conductive. The thermally conductive EMI absorber may be silicone-free, silicone-free (e.g., completely silicone-free, substantially silicone-free, no detectable silicone, etc.), and / or usable without silicone migration, making the thermally conductive EMI absorber suitable for silicone-sensitive applications. In an alternative embodiment, the thermally conductive EMI absorber comprises a silicone-based matrix system.

[0024] The thermally conductive EMI absorber may be configured as a gap filler pad, a phase change material, a putty, a grease, or a sheet material. For example, the thermally conductive EMI absorber may include a thermoplastic pad configured to undergo physical cross-linking (but not chemical cross-linking) when cooled from an elevated temperature to room temperature (e.g., about 20 degrees Celsius (°C)).

[0025] In another exemplary embodiment, the thermally conductive EMI absorber includes a matrix and at least one functional filler in the matrix. In this example, the at least one functional filler includes or consists essentially of zinc oxide, silicon carbide, and aluminum nitride. The matrix also includes or consists essentially of a paraffinic processing oil, a styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and a coupling agent. Continuing with this example, the thermally conductive EMI absorber includes at least 90% by weight (e.g., at least 93% by weight) of the at least one functional filler (zinc oxide, silicon carbide, aluminum nitride) and 10% by weight or less (e.g., 7% by weight or less) of the matrix. The thermally conductive EMI absorber also includes at least 80% by volume (e.g., at least 81% by volume) of the at least one functional filler (zinc oxide, silicon carbide, aluminum nitride) and 20% by volume or less (e.g., 19% by volume or less) of the matrix. For example, the thermally conductive EMI absorber may include about 1.5% to about 2% by weight of zinc oxide, about 16% to about 19% by weight of aluminum nitride, about 70% to about 80% by weight of silicon carbide, about 4% to about 6% by weight of paraffinic processing oil, about 0.4% to about 0.8% by weight of a styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and about 0.5% to about 1% by weight of a coupling agent. The thermally conductive EMI absorber has a thermal conductivity of at least 11 W / mK (e.g., 11 W / mK, 12 W / mK, greater than 12 W / mK, etc.). The thermally conductive EMI absorber has an attenuation of greater than 15 decibels per centimeter (dB / cm) at frequencies equal to or greater than 10 gigahertz (GHz), greater than 34 dB / cm at frequencies equal to or greater than 20 GHz, greater than 66 dB / cm at frequencies equal to or greater than 40 GHz, and / or greater than 90 dB / cm at frequencies equal to or greater than 60 GHz. The thermally conductive EMI absorber has a hardness of less than or equal to about 68 Shore 00 at 3 seconds and less than or equal to about 55 Shore 00 at 30 seconds. The thermally conductive EMI absorber is dielectric, not conductive. Because the thermally conductive EMI absorber does not contain silicone and is silicone-free, the thermally conductive EMI absorber can be used without causing silicone migration.The thermally conductive EMI absorber may be configured as a gap filler pad, a phase change material, a putty, a grease, or a sheet material.

[0026] In another exemplary embodiment, the thermally conductive EMI absorber includes a matrix and at least one functional filler in the matrix. In this example, the at least one functional filler includes or consists essentially of carbonyl iron, silicon carbide, zinc oxide, aluminum nitride, and aluminum oxide. The matrix also includes or consists essentially of paraffinic processing oil, a styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and a coupling agent. Continuing with this example, the thermally conductive EMI absorber includes at least 90 wt % (e.g., at least 95 wt %) of the at least one functional filler (carbonyl iron, silicon carbide, zinc oxide, aluminum nitride, and aluminum oxide) and 10 wt % or less (e.g., 5 wt % or less) of the matrix. The thermally conductive EMI absorber also includes at least 80% by volume (e.g., at least 83% by volume) of at least one functional filler (carbonyl iron, silicon carbide, zinc oxide, aluminum nitride, and aluminum oxide) and 20% by volume or less (e.g., 17% by volume or less) of a matrix. For example, the thermally conductive EMI absorber may include about 23% by weight to about 29% by weight of carbonyl iron, about 0.8% by weight to about 1.2% by weight of zinc oxide, about 5% by weight to about 5.7% by weight of aluminum nitride, about 58% by weight to about 67% by weight of silicon carbide, about 16% by weight to about 21% by weight of aluminum oxide, about 3% by weight to about 5% by weight of paraffinic processing oil, about 0.3% by weight to about 0.7% by weight of a styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and about 0.4% by weight to about 0.6% by weight of a coupling agent. The thermally conductive EMI absorber has a thermal conductivity of at least 11 W / mK (e.g., 11 W / mK, 12 W / mK, greater than 12 W / mK, etc.). The thermally conductive EMI absorber has an attenuation of greater than 15 decibels per centimeter (dB / cm) at frequencies equal to or greater than 10 gigahertz (GHz), greater than 34 dB / cm at frequencies equal to or greater than 20 GHz, greater than 66 dB / cm at frequencies equal to or greater than 40 GHz, and / or greater than 90 dB / cm at frequencies equal to or greater than 60 GHz. The thermally conductive EMI absorber has a hardness of less than or equal to about 68 Shore 00 at 3 seconds and less than or equal to about 55 Shore 00 at 30 seconds.Thermally conductive EMI absorbers are dielectric, not conductive. Because they do not contain silicone and are silicone-free, they can be used without causing silicone migration. Thermally conductive EMI absorbers are configured as gap filler pads, phase change materials, putty, grease, or sheet materials.

[0027] In another exemplary embodiment, the thermally conductive EMI absorber includes a matrix and at least one functional filler in the matrix. In this example, the at least one functional filler includes or consists essentially of zinc oxide, silicon carbide, and aluminum nitride. The matrix also includes or consists essentially of a paraffinic processing oil, a styrene-ethylene-butylene-styrene (SEBS) linear polymer having a triblock structure, a styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and a coupling agent. Continuing with this example, the thermally conductive EMI absorber includes at least 90% by weight (e.g., at least 93% by weight) of the at least one functional filler (zinc oxide, silicon carbide, aluminum nitride) and 10% by weight or less (e.g., 7% by weight or less) of the matrix. The thermally conductive EMI absorber also includes at least 80% by volume (e.g., at least 81% by volume) of the at least one functional filler (zinc oxide, silicon carbide, aluminum nitride) and 20% by volume or less (e.g., 19% by volume or less) of the matrix. For example, the thermally conductive EMI absorber may include about 1.5% to about 2% by weight of zinc oxide, about 16% to about 19% by weight of aluminum nitride, about 70% to about 80% by weight of silicon carbide, about 4% to about 6% by weight of paraffinic processing oil, about 0.2% to about 0.4% by weight of a styrene-ethylene-butylene-styrene (SEBS) linear polymer having a triblock structure, about 0.2% to about 0.4% by weight of a styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and about 0.5% to about 1% by weight of a coupling agent. The thermally conductive EMI absorber has a thermal conductivity of at least 11 W / mK (e.g., 11 W / mK, 12 W / mK, greater than 12 W / mK, etc.). The thermally conductive EMI absorber has an attenuation of greater than 15 decibels per centimeter (dB / cm) at frequencies equal to or greater than 10 gigahertz (GHz), greater than 34 dB / cm at frequencies equal to or greater than 20 GHz, greater than 66 dB / cm at frequencies equal to or greater than 40 GHz, and / or greater than 90 dB / cm at frequencies equal to or greater than 60 GHz. The thermally conductive EMI absorber has a hardness of less than or equal to about 68 Shore 00 at 3 seconds and less than or equal to about 55 Shore 00 at 30 seconds.Thermally conductive EMI absorbers are dielectric, not conductive. Because they do not contain silicone and are silicone-free, they can be used without causing silicone migration. Thermally conductive EMI absorbers are configured as gap filler pads, phase change materials, putty, grease, or sheet materials.

[0028] In another exemplary embodiment, the thermally conductive EMI absorber includes a matrix and at least one functional filler in the matrix. In this example, the at least one functional filler includes or consists essentially of carbonyl iron, silicon carbide, zinc oxide, aluminum nitride, and aluminum oxide. The matrix also includes or consists essentially of paraffinic processing oil, a styrene-ethylene-butylene-styrene (SEBS) linear polymer having a triblock structure, a styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and a coupling agent. Continuing with this example, the thermally conductive EMI absorber includes at least 90 wt % (e.g., at least 95 wt %) of the at least one functional filler (carbonyl iron, silicon carbide, zinc oxide, aluminum nitride, and aluminum oxide) and 10 wt % or less (e.g., 5 wt % or less) of the matrix. The thermally conductive EMI absorber also includes at least 80% by volume (e.g., at least 83% by volume) of at least one functional filler (carbonyl iron, silicon carbide, zinc oxide, aluminum nitride, and aluminum oxide) and 20% by volume or less (e.g., 17% by volume or less) of a matrix. For example, the thermally conductive EMI absorber may comprise about 23% to about 29% by weight carbonyl iron, about 0.8% to about 1.2% by weight zinc oxide, about 5% to about 5.7% by weight aluminum nitride, about 58% to about 67% by weight silicon carbide, about 16% to about 21% by weight aluminum oxide, about 3% to about 5% by weight paraffinic processing oil, about 0.2% to about 0.4% by weight styrene-ethylene-butylene-styrene (SEBS) linear polymer having a triblock structure, about 0.1% to about 0.3% by weight styrene-ethylene-propylene (SEP) linear polymer having a diblock structure, and about 0.4% to about 0.6% by weight coupling agent. The thermally conductive EMI absorber has a thermal conductivity of at least 11 W / mK (e.g., 11 W / mK, 12 W / mK, greater than 12 W / mK, etc.).The thermally conductive EMI absorber has an attenuation of greater than 15 decibels per centimeter (dB / cm) at frequencies equal to or greater than 10 gigahertz (GHz), greater than 34 dB / cm at frequencies equal to or greater than 20 GHz, greater than 66 dB / cm at frequencies equal to or greater than 40 GHz, and / or greater than 90 dB / cm at frequencies equal to or greater than 60 GHz. The thermally conductive EMI absorber has a hardness of less than or equal to about 68 Shore 00 at 3 seconds and less than or equal to about 55 Shore 00 at 30 seconds. The thermally conductive EMI absorber is dielectric, not conductive. Because the thermally conductive EMI absorber does not contain silicone and is silicone-free, the thermally conductive EMI absorber can be used without silicone migration. The thermally conductive EMI absorber is configured as a gap filler pad, phase change material, putty, grease, or sheet material.

[0029] In another exemplary embodiment, the thermally conductive EMI absorber includes a matrix and at least one functional filler in the matrix. In this example, the at least one functional filler includes or consists essentially of silicon carbide and aluminum oxide. The matrix also includes or consists essentially of a process oil, a diblock polymer, a coupling agent, an antioxidant, and silica. Continuing with this example, the thermally conductive EMI absorber includes at least 90 wt % (e.g., at least 94.5 wt %) of the at least one functional filler (silicon carbide and aluminum oxide) and 6 wt % or less (e.g., 5.5 wt % or less) of the matrix. The thermally conductive EMI absorber also includes at least 80 vol % of the at least one functional filler (silicon carbide and aluminum oxide) and less than 20 vol % of the matrix. For example, the thermally conductive EMI absorber may include about 69% to about 74% by weight silicon carbide, about 20% to about 25% by weight aluminum oxide, about 2.5% to about 5% by weight process oil, about 0.3% to about 0.7% by weight diblock polymer, about 0.2% to about 0.6% by weight coupling agent, about 0.5% to about 0.9% by weight silica, and less than about 0.1% by weight antioxidant. The thermally conductive EMI absorber has a thermal conductivity of at least 11 W / mK (e.g., 11 W / mK, 12 W / mK, greater than 12 W / mK, etc.). The thermally conductive EMI absorber has an attenuation of greater than 15 decibels per centimeter (dB / cm) at frequencies equal to or greater than 10 gigahertz (GHz), greater than 34 dB / cm at frequencies equal to or greater than 20 GHz, greater than 66 dB / cm at frequencies equal to or greater than 40 GHz, and / or greater than 90 dB / cm at frequencies equal to or greater than 60 GHz. The thermally conductive EMI absorber has a hardness of less than or equal to about 58 Shore 00 at 3 seconds and less than or equal to about 37 Shore 00 at 30 seconds. The thermally conductive EMI absorber is dielectric, not conductive. Because the thermally conductive EMI absorber does not contain silicone and is silicone-free, the thermally conductive EMI absorber can be used without silicone migration. The thermally conductive EMI absorber is configured as a gap filler pad, phase change material, putty, grease, or sheet material.

[0030] In another exemplary embodiment, the thermally conductive EMI absorber includes a matrix and at least one functional filler in the matrix. In this example, the at least one functional filler includes stainless steel. The at least one functional filler may further include one or more of zinc oxide, silicon carbide, carbonyl iron, aluminum oxide, aluminum nitride, aluminum, boron nitride, silicon nitride, iron, graphite, ferrite, alumina trihydrate, silica, iron silicide, manganese zinc-based ferrite, nickel zinc-based ferrite, and / or magnetic metal powder. The matrix includes a silicone polymer matrix. Continuing with this example, the thermally conductive EMI absorber includes at least 90% by weight (e.g., at least about 96% by weight) of the at least one functional filler (stainless steel and other functional fillers) and 10% by weight or less (e.g., about 4% by weight or less) of the matrix. The thermally conductive EMI absorber also includes at least 80% by volume (e.g., at least about 82% by volume) of at least one functional filler (stainless steel and other functional fillers) and less than 20% by volume (e.g., about 16% by volume or less) of matrix. The thermally conductive EMI absorber has a thermal conductivity of at least 5 W / mK and an attenuation in the range of about 1 dB / cm to about 15 dB / cm at a frequency in the range of 1 MHz to 2 GHz. The thermally conductive EMI absorber may be dielectric rather than conductive. The thermally conductive EMI absorber may be usable without substantial silicone migration. The thermally conductive EMI absorber may be configured as a gap filler.

[0031] In another exemplary embodiment, the thermally conductive EMI absorber includes a matrix and at least one functional filler in the matrix (e.g., a silicone mix containing ceramic and magnetic fillers in a homogeneous form). In this example, the at least one functional filler includes stainless steel, alumina, and an iron silicide filler / manganese zinc ferrite filler. The matrix includes a silicone matrix binder. Continuing with this example, the thermally conductive EMI absorber includes about 53 wt. % stainless steel filler, about 33 wt. % alumina, about 10 wt. % iron silicide filler / manganese zinc ferrite filler, and about 4 wt. % silicone matrix binder. The thermally conductive EMI absorber has a thermal conductivity of about 5 W / mK and attenuation of at least about 1 dB / cm at 1 MHz, at least about 5 dB / cm at 1 GHz, at least about 10 dB / cm at 2 GHz, and at least about 20 dB / cm at 4 GHz. The noise attenuation at 1 GHz is preferably in the range of 10-15 dB for the return loss peak. The thermally conductive EMI absorber can be configured as a gap filler that undergoes a room temperature and / or high temperature curing process. The thermally conductive EMI absorber can be provided as a sheet or die-cut part (typically a pad) with release liners on both sides. The thermally conductive EMI absorber is both thermally conductive and low-frequency EMI absorbing. The thermally conductive EMI absorber (as a whole) is preferably dielectric and not electrically conductive. The thermally conductive EMI absorber can be used in a variety of applications, such as optical transceivers, OLED and / or LED devices (e.g., TVs, tablets, etc.), computer chips, solid-state drives, etc. The silicone matrix can include a soft, two-part, platinum-cure silicone having a hardness in the range of approximately 40-50 Shore 00. The alumina filler provides thermal conductivity. The stainless steel filler can have a particle size in the range of approximately 4 μm to approximately 8 μm. The stainless steel filler helps absorb EMI at low frequencies and also provides thermal conductivity. The iron silicide filler can have a hemispherical shape and a particle size of approximately 24 μm. The iron silicide filler and manganese zinc ferrite filler help absorb EMI at low frequencies.In other exemplary embodiments, the at least one functional filler may include nickel-zinc ferrite in combination with or in place of the manganese-zinc ferrite filler. Typically, manganese-zinc ferrite and nickel-zinc ferrite perform similarly depending on particle size and loading, but manganese-zinc ferrite performs better at low frequencies below 1 GHz, while nickel-zinc ferrite performs better between 1 GHz and 2 GHz.

[0032] By way of illustration, Tables 1 and 2 below include exemplary properties that a thermally conductive EMI absorber may have in exemplary embodiments. As shown in Table 1 below, exemplary embodiments of a thermally conductive EMI absorber may have a thermal conductivity of at least about 12 watts per meter-Kelvin (W / mK), a density of about 3 grams per cubic centimeter (g / cc), a hardness of about 58 Shore 00 or less at 3 seconds, a hardness of about 37 Shore 00 or less at 30 seconds, a deflection of about 9.6% at 38 kPa on a 1 mm thick sample, a deflection of about 34.4% at 345 kPa on a 1 mm thick sample, an operating temperature range of about -40°C to about 125°C, etc.

[0033] As shown in Table 2 below, another exemplary embodiment of the thermally conductive EMI absorber may have a thermal conductivity of at least about 11.5 W / mK, a density of about 2.96 g / cc, a hardness of about 58 Shore 00 or less at 3 seconds, a hardness of about 31 Shore 00 or less at 30 seconds, a deflection of about 76% at 10 pounds per square inch (psi) (68.9 kPa) on a 1 mm thick sample, a deflection of about 39% at 50 pounds per square inch (psi) (345 kPa) on a 1 mm thick sample, an operating temperature range of about −40° C. to about 125° C., etc. Additionally, the thermally conductive EMI absorber may be lead-free in compliance with REACH and ROHS regulations and may have a UL flammability rating of UL V-0. Also, as shown in Table 2, the thermally conductive EMI absorber may have the following electromagnetic properties: 22 dB / cm attenuation at 10 GHz, 39 dB / cm attenuation at 20 GHz, 53 dB / cm attenuation at 28 GHz, 76 dB / cm attenuation at 39 GHz, and 135 dB / cm attenuation at 77 GHz.

[0034] The thermal conductivities disclosed in Tables 1 and 2 below, as well as other thermal conductivities disclosed herein, were measured by a hot disk thermal constant analyzer. In other exemplary embodiments, the thermally conductive EMI absorber may be configured differently, for example, to have one or more properties different from those shown in Tables 1 and 2 (e.g., a thermal conductivity of at least 6 W / mK, a thermal conductivity of at least about 11 W / mK, etc.).

[0035] [Table 1]

[0036] [Table 2]

[0037] In an exemplary embodiment, the thermally conductive EMI absorber may include a silicone-free hybrid absorber / thermal management material with an extremely high thermal conductivity of at least 11 W / mK (e.g., 11.5 W / mK, 12 W / mK, etc.). The thermally conductive EMI absorber may be used similarly to a traditional thermal interface material between a heat source (e.g., a high-power integrated circuit (IC), an optical transceiver, a 5G infrastructure device, etc.) and a heat dissipation / transfer device (e.g., a heat sink, a metal chassis, other heat removal structure, etc.). The thermally conductive EMI absorber also functions to suppress unwanted energy coupling, resonance, or surface currents that can cause board-level EMI problems.

[0038] Exemplary embodiments of the thermally conductive EMI absorber disclosed herein may have one or more (but not necessarily some or all) of the following exemplary advantages or features: Very high thermal conductivity to meet the industry trend of increasing IC power; Good EMI suppression over a wide frequency range, e.g., above 25 GHz, above 60 GHz; · Silicone-free formulations suitable for silicone-sensitive applications; · Inherent surface tack; ·Component stresses during assembly are minimized or at least reduced; · Space-saving and performance benefits derived from two functional properties: thermal conductivity and EMI reduction; Improved reliability performance of electronic devices, for example, improved signal integrity due to reduced EMI, consistent performance of electronic devices due to temperature stability and low outgassing characteristics of the product; · Improved electromagnetic compatibility (EMC) performance to meet compliance requirements; Passes UL94 V-0 requirements; and Environmentally friendly solutions that meet regulatory requirements including RoHS and REACH.

[0039] In exemplary embodiments, the thermally conductive EMI absorber provides a dual-purpose single product that can be used in a wide range of industries and applications, including, for example, applications including ADAS (Advanced Driver Assistance Systems) radar, high speed data transmission, microwave transmission, satellites, space, cancer detection and treatment, wireless high speed connectivity, 5G mmWave technology, SSR (Split Ring Resonator) technology, optical transceivers, and the like.

[0040] In an exemplary embodiment, the thermally conductive EMI absorber may be provided as a 457 mm x 457 mm (18 inches x 18 inches) sheet with a thickness in the range of about 0.02 inches to 0.16 inches, or about 0.5 mm to about 4 mm. For example, the thermally conductive EMI absorber may be provided in thicknesses of about 0.5 mm (about 0.02 inches), 0.8 mm (0.03 inches), 1 mm (0.04 inches), 1.5 mm (0.06 inches), 2 mm (0.08 inches), etc.

[0041] In exemplary embodiments, a thermally conductive EMI absorber may be used to define or provide a portion of a thermally conductive heat path from a heat source to a heat removal / dissipation structure or component. The thermally conductive EMI absorber may be used, for example, to help conduct thermal energy (e.g., heat) away from a heat source in an electronic device. The thermally conductive EMI absorber may be positioned typically between (e.g., in direct physical or thermal contact with) the heat source and the heat removal / dissipation structure or component to establish a thermal junction, interface, pathway, or thermally conductive heat path along which heat is transferred (e.g., conducted) from the heat source to the heat removal / dissipation structure or component. During operation, the thermally conductive EMI absorber may function to transfer heat (e.g., conduct heat) from the heat source along the thermally conductive path to the heat removal / dissipation structure or component. The thermally conductive EMI absorber may also operate to mitigate (e.g., absorb) EMI incident on the thermally conductive EMI absorber.

[0042] In an exemplary embodiment, an electronic device includes a heat source and a thermally conductive EMI absorber as disclosed herein, the thermally conductive EMI absorber positioned relative to the heat source to establish a thermally conductive heat path from the heat source.

[0043] In an exemplary embodiment, an electronic device includes a heat source, a heat removal / dissipation structure, and a thermally conductive EMI absorber as disclosed herein, the thermally conductive EMI absorber being between the heat source and the heat removal / dissipation structure.

[0044] In an exemplary embodiment, the electronic device includes a heat source, an EMI shield, and a thermally conductive EMI absorber as disclosed herein. The thermally conductive EMI absorber is between the heat source and the EMI shield. The electronic device may further include a heat removal / dissipation device and a thermal interface material between the EMI shield and the heat removal / dissipation device. The heat source may be an integrated circuit. The EMI shield may be a board-level shield. The heat removal / dissipation structure may be a heat sink. The thermal interface material may be between the board-level shield and the heat sink to establish a thermally conductive heat path from the board-level shield to the heat sink. The thermally conductive EMI absorber may be between the integrated circuit and the heat sink to establish a thermally conductive heat path from the integrated circuit to the board-level shield and to reduce coupling of radiated electromagnetic fields between the integrated circuit and the heat sink.

[0045] Exemplary embodiments disclosed herein may be used with a wide range of heat sources, electronic devices, and / or heat removal / dissipation structures or components (e.g., heat spreaders, heat sinks, heat pipes, vapor chambers, external device cases, housings, or chassis, etc.) For example, a heat source may include one or more heat-generating components or devices, such as high-power integrated circuits (ICs), optical transceivers, 5G infrastructure devices (e.g., base stations, small cells, smart poles, etc.), memory in video cards, set-top boxes, televisions, gaming systems, automotive electronics used in autonomous driving (ADAS) (e.g., radar, multi-domain controllers, cameras, etc.), CPUs, die-in-underfill, semiconductor devices, flip-chip devices, graphics processing units (GPUs), digital signal processors (DSPs), multiprocessor systems, integrated circuits (ICs), multi-core processors, etc. In general, a heat source may include any component or device that has a higher temperature than the thermally conductive EMI absorber or that transfers heat to the thermally conductive EMI absorber, whether the heat is generated by the heat source or simply transferred through or via the heat source. Thus, embodiments of the present disclosure should not be limited to use with a single type of heat source, electronic device, heat removal / dissipation structure, or the like.

[0046] The exemplary embodiments are provided so that this disclosure will be thorough and will fully convey the scope to those 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 the embodiments of the present disclosure. It will be apparent to those skilled in the art that the use of specific details is not necessary, that the exemplary embodiments can be embodied in many different forms, and that neither should be construed as limiting the scope of the present disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. Furthermore, advantages and improvements that may be achieved in one or more exemplary embodiments of the present disclosure are provided for illustrative purposes only and do not limit the scope of the present disclosure, as an exemplary embodiment of the present disclosure may provide all or none of the above advantages and improvements and still be within the scope of the present disclosure.

[0047] The specific dimensions, specific materials, and / or specific shapes disclosed herein are exemplary in nature and do not limit the scope of the present disclosure. The disclosure herein of a specific value and a specific range of values ​​for a given parameter does not exclude other values ​​and ranges of values ​​that may be useful in one or more examples disclosed herein. Furthermore, it is contemplated that any two specific values ​​for a particular parameter described herein may define the endpoints of a range of values ​​that may be suitable 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 ​​can be used for the particular parameter). For example, if parameter X is exemplified herein as having a value A and also as having a value Z, it is contemplated that parameter X may have a range of values ​​from about A to about Z. Similarly, the disclosure of two or more ranges of values ​​for a parameter (whether such ranges are nested, overlapping, or separate) is contemplated to encompass all possible combinations of ranges of values ​​that may be claimed using the endpoints of the disclosed ranges. For example, if a parameter X is exemplified herein as having a value in the range of 1 to 10, or 2 to 9, or 3 to 8, it is also contemplated that the parameter X may have other ranges of values, including 1 to 9, 1 to 8, 1 to 3, 1 to 2, 2 to 10, 2 to 8, 2 to 3, 3 to 10, and 3 to 9.

[0048] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. For example, when permissive phrases such as "may include" or "may include" are used herein, at least one embodiment includes the feature. As used herein, the singular forms "a," "an," and "the" may be intended to include the plural forms as well, unless the context clearly dictates otherwise. The terms "comprise," "include," and "have" are inclusive and thus specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Method steps, processes, and operations described herein should not be construed as necessarily requiring their performance in the particular order described or illustrated, unless specifically identified as an order of performance. It should also be understood that additional or alternative steps may be employed.

[0049] When an element or layer is described as "on," "engaged with," "connected to," or "bonded to" another element or layer, it may be directly on, engaged with, connected to, or bonded to that other element or layer, or to intervening elements or layers that may be present. In contrast, when an element is described as "directly on," "directly engaged with," "directly connected to," or "directly bonded to" another element or layer, there may be no intervening elements or layers. Other words used to describe relationships between elements should be interpreted in a similar manner (e.g., "between" and "directly between," "adjacent" and "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0050] The term "about," when applied to a value, indicates that the calculation or measurement allows for slight imprecision in the value (approximately or reasonably close to the value, depending on the approach to the accuracy of the value; approximately). If, for some reason, the imprecision provided by "about" is not understood in this ordinary sense in the art, "about," as used herein, refers to at least the variation that can result from ordinary methods of measuring or using such parameters. For example, the terms "generally," "about," and "substantially" can be used herein to mean within manufacturing tolerances. Alternatively, for example, the term "about," as used herein, when used to vary the amounts of components or reactants of the present invention, refers to variations in numerical values ​​that can occur, for example, in typical measuring and handling procedures used in producing concentrates or solutions in the real world, through inadvertent errors in these procedures, or through differences in the manufacture, source, or purity of components used to make the composition or carry out the method. The term "about" also encompasses amounts that differ due to different equilibrium conditions of a composition resulting from a particular initial mixture. Numerical quantities and equivalents are included regardless of whether they are modified by the term "about."

[0051] Terms such as "first," "second," and "third" may be used herein to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or section from another region, layer, or section. When used herein, terms such as "first," "second," and other numerical terms do not imply an order or sequence unless clearly indicated by context. Thus, a first element, component, region, layer, or section discussed below could be referred to as a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0052] Spatially relative terms such as "inside," "outside," "below," "down," "lower," "upper," "above," and the like may be used herein to facilitate the description of the relationship of one element or feature to another, as shown in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. For example, if the device in the figures is turned over, elements described as "below" or "below" other elements or features would then become "above" the other elements or features. Thus, the example term "below" can encompass both an orientation of above and below. The device may be oriented differently (rotated 90 degrees or in another orientation), and the spatially relative descriptors used herein may be interpreted accordingly.

[0053] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements, intended or described uses, or features of a particular embodiment are in most cases not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in selected embodiments even if not specifically shown or described. The same can also be modified in many ways. Such modifications should not be considered a departure from the disclosure, and all such variations are intended to be included within the scope of the disclosure.

Claims

1. 1. A thermally conductive electromagnetic interference (EMI) absorber comprising a matrix and at least one functional filler in the matrix, the at least one functional filler comprises stainless steel; and The thermally conductive EMI absorber has an attenuation in the range of about 1 decibel per centimeter to about 15 decibels per centimeter at frequencies in the range of 1 megahertz to 2 gigahertz.

2. 10. The thermally conductive EMI absorber of claim 1 having a thermal conductivity of at least about 5 watts per meter Kelvin.

3. 10. The thermally conductive EMI absorber of claim 1, wherein the at least one functional filler further comprises one or more of zinc oxide, silicon carbide, carbonyl iron, aluminum oxide, aluminum nitride, aluminum, boron nitride, silicon nitride, iron, graphite, ferrite, alumina trihydrate, silica, iron silicide, manganese zinc based ferrite, nickel zinc based ferrite, and magnetic metal powder.

4. the thermally conductive EMI absorber comprises at least 90% by weight of the at least one functional filler and no more than 10% by weight of the matrix; and / or 10. The thermally conductive EMI absorber of claim 1, wherein the thermally conductive EMI absorber comprises at least 80% by weight of the at least one functional filler and no more than 20% by weight of the matrix.

5. the thermally conductive EMI absorber comprises at least about 96% by weight of the at least one functional filler and no more than about 4% by weight of the matrix; and / or 10. The thermally conductive EMI absorber of claim 1, wherein the thermally conductive EMI absorber comprises at least about 82% by weight of the at least one functional filler and no more than about 16% by weight of the matrix.

6. the at least one functional filler further comprises one or more of zinc oxide, silicon carbide, carbonyl iron, aluminum oxide, aluminum nitride, aluminum, boron nitride, silicon nitride, iron, graphite, ferrite, alumina trihydrate, silica, iron silicide, and magnetic metal powder; and 6. The thermally conductive EMI absorber of claim 5, wherein the thermally conductive EMI absorber has a thermal conductivity of at least about 5 watts per meter Kelvin.

7. the at least one functional filler comprises alumina, iron silicide, and manganese zinc ferrite; the matrix comprises a silicone matrix; and 10. The thermally conductive EMI absorber of claim 1, wherein the thermally conductive EMI absorber comprises, by weight, about 53% stainless steel, about 33% alumina, about 10% iron silicide / manganese zinc ferrite, and about 4% silicone matrix.

8. The at least one functional filler is manganese zinc ferrite, Nickel-zinc ferrite, or Manganese-zinc ferrite and nickel-zinc ferrite The thermally conductive EMI absorber of claim 1 further comprising:

9. an attenuation of at least about 1 decibel per centimeter at a frequency of 1 megahertz; an attenuation of at least about 5 decibels per centimeter at a frequency of 1 gigahertz; an attenuation of at least about 10 decibels per centimeter at a frequency of 2 gigahertz; and an attenuation of at least about 20 decibels per centimeter at a frequency of 4 gigahertz; The thermally conductive EMI absorber of any one of claims 1 to 8, comprising one or more of:

10. an attenuation of at least about 1 decibel per centimeter at a frequency of 1 megahertz; an attenuation of at least about 5 decibels per centimeter at a frequency of 1 gigahertz; an attenuation of at least about 10 decibels per centimeter at a frequency of 2 gigahertz; and an attenuation of at least about 20 decibels per centimeter at a frequency of 4 gigahertz; The thermally conductive EMI absorber of any one of claims 1 to 8, comprising:

11. 1. A thermally conductive electromagnetic interference (EMI) absorber comprising a matrix and at least one functional filler in the matrix, wherein the at least one functional filler comprises stainless steel; the thermally conductive EMI absorber comprises at least 90% by weight of the at least one functional filler and no more than 10% by weight of the matrix; and / or The thermally conductive EMI absorber comprises at least 80% by weight of the at least one functional filler and no more than 20% by weight of the matrix.

12. 12. The thermally conductive EMI absorber of claim 11, wherein the thermally conductive EMI absorber has a thermal conductivity of at least about 5 watts per meter Kelvin.

13. 13. The thermally conductive EMI absorber of claim 12, having an attenuation in the range of about 1 decibel per centimeter to about 15 decibels per centimeter at frequencies in the range of 1 megahertz to 2 gigahertz.

14. 12. The thermally conductive EMI absorber of claim 11, wherein the at least one functional filler further comprises one or more of zinc oxide, silicon carbide, carbonyl iron, aluminum oxide, aluminum nitride, aluminum, boron nitride, silicon nitride, iron, graphite, ferrite, alumina trihydrate, silica, iron silicide, manganese zinc based ferrite, nickel zinc based ferrite, and magnetic metal powder.

15. the thermally conductive EMI absorber comprises at least about 96% by weight of the at least one functional filler and no more than about 4% by weight of the matrix; and / or 12. The thermally conductive EMI absorber of claim 11, wherein the thermally conductive EMI absorber comprises at least about 82% by weight of the at least one functional filler and no more than about 16% by weight of the matrix.

16. the at least one functional filler further comprises one or more of zinc oxide, silicon carbide, carbonyl iron, aluminum oxide, aluminum nitride, aluminum, boron nitride, silicon nitride, iron, graphite, ferrite, alumina trihydrate, silica, iron silicide, and magnetic metal powder; and 16. The thermally conductive EMI absorber of claim 15, wherein the thermally conductive EMI absorber has a thermal conductivity of at least about 5 watts per meter Kelvin.

17. the at least one functional filler comprises alumina, iron silicide, and manganese zinc ferrite; the matrix comprises a silicone matrix; and 12. The thermally conductive EMI absorber of claim 11, wherein the thermally conductive EMI absorber comprises about 53% by weight stainless steel, about 33% by weight alumina, about 10% by weight iron silicide / manganese zinc ferrite, and about 4% by weight silicone matrix.

18. The at least one functional filler is manganese zinc ferrite, Nickel-zinc ferrite, or Manganese-zinc ferrite and nickel-zinc ferrite 12. The thermally conductive EMI absorber of claim 11, further comprising:

19. an attenuation of at least about 1 decibel per centimeter at a frequency of 1 megahertz; an attenuation of at least about 5 decibels per centimeter at a frequency of 1 gigahertz; an attenuation of at least about 10 decibels per centimeter at a frequency of 2 gigahertz; and an attenuation of at least about 20 decibels per centimeter at a frequency of 4 gigahertz; The thermally conductive EMI absorber of any one of claims 11 to 18, comprising one or more of:

20. an attenuation of at least about 1 decibel per centimeter at a frequency of 1 megahertz; an attenuation of at least about 5 decibels per centimeter at a frequency of 1 gigahertz; an attenuation of at least about 10 decibels per centimeter at a frequency of 2 gigahertz; and an attenuation of at least about 20 decibels per centimeter at a frequency of 4 gigahertz; The thermally conductive EMI absorber of any one of claims 11 to 18, comprising:

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