Electromagnetic Interference (EMI) Mitigation Materials and EMI Absorber Devices Including Carbon Nanotubes

Abstract

Exemplary embodiments of electromagnetic interference (EMI) absorbing compositions are disclosed, including an EMI mitigation material and carbon nanotubes. The carbon nanotubes can include carbon nanostructures including branched networks of single-walled carbon nanotubes, multi-walled carbon nanotubes, and / or cross-linked carbon nanotube structures. For example, exemplary embodiments can include compositions including carbon nanotubes within a polymer resin, whereby the composition is operable to absorb noise and / or reflect signals, thereby inhibiting the passage or transmission of signals through the composition. Also, for example, exemplary embodiments can include broadband millimeter-wave EMI absorbers including carbon nanotubes.

Description

[Technical Field]

[0001] The present disclosure relates to electromagnetic interference (EMI) absorbing compositions comprising an EMI mitigating material and carbon nanotubes (eg, single-walled carbon nanotubes, multi-walled carbon nanotubes, and / or carbon nanostructures). [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 conduction 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] Furthermore, a common problem in the operation of electronic devices is the generation of electromagnetic radiation within the equipment's electronic circuitry. 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 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] 1A-1E show exemplary pyramidal patterns of materials according to one exemplary embodiment. [Figure 2]2A-2E each illustrate an exemplary process step associated with fabricating a pattern in a filled dielectric system according to an exemplary embodiment. [Figure 3] 1 illustrates a multilayer film structure including a block copolymer film having through-thickness domains, according to an exemplary embodiment. [Figure 4] 1 illustrates a multilayer film structure according to an exemplary embodiment, in which the filler density per layer increases from the top layer to the bottom layer. [Figure 5] 1 illustrates a filled dielectric with pyramidal structures according to an exemplary embodiment, in which the pyramidal structures contain air-filled microballoons, microspheres, or microbubbles therein. [Figure 6] 1 illustrates an exemplary embodiment including a pyramidal structure, a planarization layer, and a multi-layer frequency selective surface (FSS) structure. [Figure 7] 1 illustrates a pyramidal structure along a portion of a board level shield (BLS) according to an exemplary embodiment. [Figure 8] 1 illustrates pyramidal structures along a portion of a BLS according to an exemplary embodiment in which one or more pyramidal structures have a different size (e.g., different heights, randomized or non-randomized) than one or more other pyramidal structures. [Figure 9] 1 shows pyramidal structures along a portion of a BLS according to an exemplary embodiment in which the pyramidal structures include air-filled microballoons, microspheres, or microbubbles therein, e.g., to reduce the dielectric constant of the pyramidal structures. [Figure 10] 1 illustrates pyramidal structures along a portion of a BLS according to an exemplary embodiment, where at least one or more of the pyramidal structures are multi-layered and the filler density per layer increases from the top layer to the bottom layer. [Figure 11]1 illustrates a BLS and pyramidal structures along the inner or internal surfaces of the top and sidewalls of the BLS, according to an exemplary embodiment, the pyramidal structures projecting inward from the top and sidewalls of the BLS generally in a direction toward components on the substrate, such as integrated circuits (ICs) on a printed circuit board (PCB). [Figure 12] 1 illustrates a BLS and pyramidal structures along the outer or exterior surfaces of the top and side walls of the BLS, according to an exemplary embodiment, the pyramidal structures protruding outward from the top and side walls of the BLS generally in a direction away from the PCB component. [Figure 13] 1 illustrates a BLS and pyramidal structures along the top and sidewalls of the BLS, according to an exemplary embodiment, the pyramidal structures being along both the outer and inner surfaces (or exterior and interior surfaces) of the top and sidewalls of the BLS, protruding outward and inward, respectively, generally in opposite directions toward and away from the PCB component. [Figure 14] 1 illustrates both non-pyramidal and pyramidal structures along a portion of a BLS, according to an example embodiment. [Figure 15] 1 illustrates a non-pyramidal structure along a portion of a BLS, according to an example embodiment. [Figure 16] 1 illustrates an outer device case including a multilayer film and / or metamaterial configured to provide one or more of a conductor, a waveguide, an EMI absorber, a thermal interface material (TIM), and a dielectric, according to an exemplary embodiment. [Figure 17] 1 illustrates an interposer including a multilayer film and / or metamaterial configured to provide one or more of a conductor, a waveguide, an EMI absorber, a thermal interface material (TIM), and a dielectric between two PCBs, according to an exemplary embodiment. [Figure 18] 1 illustrates integrated circuit (IC) packaging including multilayer films and / or metamaterials configured to provide one or more of electrical conductors / interconnects, waveguides, EMI absorbers, thermal interface materials (TIMs), and dielectrics, according to example embodiments. [Figure 19]1 illustrates a multi-layer frequency selective surface (FSS) structure including a pattern of conductive, EMI absorbing, and / or metamaterial elements, according to an exemplary embodiment. [Figure 20] 1 illustrates a metamaterial TIM configured to provide a thermally conductive heat path and operable to direct a millimeter-wave signal primarily toward a reflector, according to an exemplary embodiment. [Figure 21] 21A and 21B illustrate an exemplary flexible material including filled dielectric pyramid structures according to an exemplary embodiment that may be fabricated by the process illustrated in FIGS. 2A-2E. [Figure 22] 1 is a perspective view of a board level shield (BLS) according to an exemplary embodiment, in which one sidewall of the BLS is made of an EMI absorbing material or absorber. [Figure 23] 23 is a line graph showing the simulated reduction in total radiated power in decibels (dB) versus frequency in gigahertz (GHz) for the board-level shield of FIG. 22, where the absorber location is different for the two cases, accompanied by a shift in the frequency of maximum total radiated power reduction. [Figure 24] 1 illustrates EMI absorbing pyramidal structures along the outside of a device component that defines a cavity or chamber, according to an example embodiment. [Figure 25] 1 illustrates a pyramidal structure for an EMI absorber according to an exemplary embodiment. [Figure 26] 26 is a line graph of reflection loss in decibels (dB) versus frequency in gigahertz (GHz) for a composition containing 0.5 volume percent (vol%) carbon nanostructures. For comparison, FIG. 26 also includes the reflection loss for a composition containing 10 vol% carbon black and a composition containing 50 vol% silicon carbide (SiC). DETAILED DESCRIPTION OF THE INVENTION

[0008] Corresponding reference numerals may indicate corresponding (but not necessarily identical) parts throughout the several views of the drawings. Detailed Description Exemplary embodiments will now be described more fully with reference to the accompanying drawings.

[0009] As recognized herein, systems that transmit energy can experience interference from reflections returning to the transmitter. These unwanted reflections can interfere with other systems. EMI absorbers containing magnetic or dielectric fillers can be used to reduce reflection levels. Typical reflectance reductions for weather-resistant outdoor EMI absorbers are -20 decibels (dB), eliminating approximately 99% of reflections. Conventional broadband millimeter-wave EMI absorbers for frequencies of 77 gigahertz (GHz) and 90 GHz may contain very high loadings of dielectric fillers, such as carbon black and / or silicon carbide, up to 20 volume percent (vol%) to achieve a -20 dB return loss. However, manufacturing such high filler loadings tends to be difficult, especially when producing EMI absorbing sheets with relatively fine pyramidal patterns.

[0010] Accordingly, disclosed herein are exemplary embodiments of EMI mitigation materials (e.g., EMI absorbers, thermally conductive EMI absorbers, etc.) comprising carbon nanotubes. The carbon nanotubes may include single-walled carbon nanotubes, multi-walled carbon nanotubes, and / or carbon nanostructures including branched networks of cross-linked carbon nanotube structures. For example, exemplary embodiments may include broadband millimeter-wave EMI absorbers comprising carbon nanotubes.

[0011] Exemplary embodiments may include carbon nanostructures (CNS) and other carbon nanotube structures with highly conductive coatings, branches, and bridges at relatively low filler loadings, such as 0.1 to 0.5 volume percent. At such low filler loadings, the CNS filler can be thoroughly mixed into a liquid silicone or other thermosetting material matrix to achieve a low viscosity. The low viscosity mixture allows the mixture to be easily poured or cast into a mold to form shapes and patterns (e.g., pyramidal patterns) configured to operate at frequencies from about 40 gigahertz (GHz) to about 120 GHz, and / or from about 60 GHz to about 90 GHz, and / or from about 70 GHz to about 85 GHz with a return loss of more than 15 decibels (e.g., more than 20 dB).

[0012] In exemplary embodiments, the CNS material is mixed into a liquid silicone or thermosetting material at a low concentration ranging from about 0.1 vol% to about 1.0 vol%, such as by using a centrifugal mixer. The composition or mixture has a low viscosity and can be easily poured into a mold to create pyramidal patterned features that provide results comparable to or better than compositions with higher loadings of carbon black (e.g., 10 vol%) or silicon carbide (SiC) (e.g., 50 vol%), as shown in Figure 26. Advantageously, the low filler loading level of the CNS in some exemplary embodiments (e.g., about 0.1 vol% to about 1.0 vol%) provides a low viscosity that facilitates manufacturing feasibility and reduces costs compared to higher filler loading levels.

[0013] In an exemplary embodiment, the EMI absorber comprises carbon nanotubes within a polymer resin, and may be operable to absorb noise and / or reflect signals, thereby inhibiting the passage or transmission of signals therethrough.

[0014] In an exemplary embodiment, an automotive component (e.g., a radar bracket, etc.) includes an EMI absorber configured with carbon black and / or carbon nanotubes in an injection-moldable resin and / or operable with a return loss of greater than 15 decibels at frequencies from about 40 gigahertz (GHz) to about 120 GHz, and / or from about 60 GHz to about 90 GHz, and / or from about 70 GHz to about 85 GHz. The EMI absorber may be operable to absorb noise and / or reflect signals, thereby inhibiting their passage or transmission through the automotive component.

[0015] In an exemplary embodiment, an injection-moldable EMI absorber composition includes carbon black and / or carbon nanotubes in an injection-moldable resin, which may be operable to absorb noise and / or reflect signals, thereby inhibiting the passage or transmission of signals through the composition.

[0016] In an exemplary embodiment, an EMI absorber composition includes carbon nanotubes in a polymer resin. The composition may be operable to absorb noise and / or reflect signals, thereby inhibiting the passage or transmission of signals through the composition. The carbon nanotubes may include one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, and / or carbon nanostructures including branched networks of bridged carbon nanotube structures.

[0017] The resin may include a thermoplastic resin. The carbon nanotubes may include single-walled carbon nanotubes in a thermoplastic resin, multi-walled carbon nanotubes in a thermoplastic resin, and / or carbon nanostructures including a branched network of cross-linked carbon nanotube structures in a thermoplastic resin. The thermoplastic resin may include one or more of liquid silicone, urethane, polycarbonate, polyamide, polyester, and / or polyolefin. In some exemplary embodiments, the thermoplastic resin includes one or more of polybutylene terephthalate, polypropylene, a thermoplastic vulcanizate, a thermoplastic elastomer, and / or a blend including a polyolefin.

[0018] The resin may comprise an injection moldable resin. The carbon nanotubes may comprise carbon nanostructures comprising single-walled carbon nanotubes in the injection moldable resin, multi-walled carbon nanotubes in the injection moldable resin, and / or a branched network of cross-linked carbon nanotube structures in the injection moldable resin.

[0019] The resin may include polypropylene and Santoprene® thermoplastic vulcanizate, and the carbon nanotubes may include carbon nanostructures. For example, an exemplary embodiment (e.g., a composition, EMI absorber, automotive part, etc.) may include about 29.5 volume percent or less of Santoprene® thermoplastic vulcanizate, about 69.5 volume percent or more of polypropylene, and about 0.5 volume percent or less of carbon nanostructures. As another example, an exemplary embodiment (e.g., a composition, EMI absorber, automotive part, etc.) may include about 10 volume percent or less of Santoprene® thermoplastic vulcanizate, about 89 volume percent or more of polypropylene, and about 0.3 volume percent or less of carbon nanostructures.

[0020] The resin may comprise a two-part silicone composition including a silicone part A and a silicone part B. The ratio of the weight percent of silicone part A to the weight percent of silicone part B may be in the range of about 1:1 to about 10:1.

[0021] The resin may comprise a two-part urethane composition including a urethane part A and a urethane part B. The ratio of the weight percent of urethane part A to the weight percent of urethane part B may be in the range of about 1:1 to about 10:1.

[0022] The resin may include a silicone or urethane resin. An exemplary embodiment (e.g., a composition, an EMI absorber, an automotive part, etc.) may include about 99.4 weight percent silicone or urethane resin and about 0.6 weight percent carbon nanotubes in the silicone or urethane resin.

[0023] Exemplary embodiments (e.g., compositions, EMI absorbers, automotive parts, etc.) may include about 98-99% by weight of resin and about 2% by weight or less of carbon nanotubes. Exemplary embodiments (e.g., compositions, EMI absorbers, automotive parts, etc.) may include about 1% by volume or less of carbon nanotubes.

[0024] Exemplary embodiments (e.g., compositions, EMI absorbers, automotive components, etc.) may be configured to operate with a return loss of greater than 15 decibels at frequencies from about 40 gigahertz (GHz) to about 120 GHz, and / or from about 60 GHz to about 90 GHz, and / or from about 70 GHz to about 85 GHz.

[0025] Exemplary embodiments (eg, compositions, EMI absorbers, automotive parts, etc.) may include up to about 0.5% by volume of carbon nanotubes. Exemplary embodiments (eg, compositions, EMI absorbers, automotive components, etc.) can be configured to operate with return losses of greater than 15 decibels at frequencies of about 77 GHz.

[0026] In exemplary embodiments (e.g., compositions, EMI absorbers, automotive parts, etc.), one or more fillers and / or additives are present in the resin. The one or more fillers and / or additives may include one or more pigments, plasticizers, processing aids, flame retardants, extenders, tackifiers, EMI absorbing fillers, conductive fillers, and / or magnetic particles.

[0027] An EMI absorber (e.g., an EMI absorbing sheet, an automotive part, an injection-molded EMI absorber, an EMI absorbing automotive part, an EMI absorbing radar bracket, etc.) can comprise and / or be formed (e.g., injection molded, etc.) from the compositions disclosed herein. For example, the EMI absorber can be injection molded from the composition such that the EMI absorber has a monolithic, integral structure. As another example, the EMI absorber can be an EMI absorbing sheet made from the composition.

[0028] The EMI absorber may include a pattern of EMI absorbing structures comprising the composition. The EMI absorbing structures may include rectangular pyramidal structures including rectangular bases configured such that the rectangular bases of adjacent rectangular pyramidal structures contact each other with substantially no gap or spacing between them. The pattern of EMI absorbing structures may include a pattern of pyramidal structures, a pattern of non-pyramidal structures, a pattern including a combination of pyramidal and non-pyramidal structures, and / or a pattern of structures including at least two structures having different predetermined or randomized heights. The EMI absorbing structures may protrude outward along a first portion of the EMI absorber. A fabric may be present along a second portion of the EMI absorber opposite the first portion from which the EMI absorbing structures protrude outward. The fabric may include one or more of a flame-retardant meta-aramid material and / or an open-weave polymer fabric, and / or the fabric may include a fabric layer along the second portion of the EMI absorber, and / or the fabric may be configured to provide reinforcement and mechanical strength to the EMI absorber.

[0029] A radar bracket may be injection molded from a composition as disclosed herein. An EMI absorbing radar bracket may include and / or be formed (e.g., injection molded, etc.) from a composition as disclosed herein. The EMI absorbing radar bracket may be configured to be positionable relative to a radar device where return loss alters radiation surrounding the radar device. The radar bracket may include a pattern of EMI absorbing structures including and / or formed (e.g., injection molded, etc.) from a composition as disclosed herein. The EMI absorbing structures may protrude outwardly along at least a portion of the radar bracket. An automobile part may include and / or be formed (e.g., injection molded, etc.) from a composition as disclosed herein. An automobile may include an automobile part and / or a radar bracket as disclosed herein.

[0030] Thermal management and EMI mitigation materials can include compositions as disclosed herein. The thermal management and EMI mitigation materials can be configured to be multifunctional, having a first function of EMI mitigation and a second function of thermal management. For example, the thermal management and EMI mitigation materials can be configured to operate at frequencies from about 40 gigahertz (GHz) to about 120 GHz with a return loss of greater than 15 decibels and have a high thermal conductivity (e.g., from about 1 W / mK (watt per meter per Kelvin) to about 10 W / mK, etc.).

[0031] The EMI mitigation material can include a composition as disclosed herein. For example, the EMI mitigation material can include a multilayer film structure defined by multiple layers having different filler densities and / or concentrations. As another example, the EMI mitigation can include a multilayer film structure defined by multiple layers including fillers dispersed within the layers to define through-thickness domains and / or to define separate, discrete regions within the layers.

[0032] In an exemplary embodiment, a method for making a composition for an EMI absorber includes blending carbon nanotubes into a polymer resin such that the composition contains less than 1% by volume of carbon nanotubes. The composition may be operable to absorb noise and / or reflect signals, thereby inhibiting the passage or transmission of signals through the composition. For example, the composition may be operable with a return loss of greater than 15 decibels at frequencies from about 40 gigahertz (GHz) to about 120 GHz and / or from about 60 GHz to about 90 GHz and / or from about 70 GHz to about 85 GHz. The composition may be operable with a return loss of greater than 15 decibels at a frequency of about 77 GHz. The composition may be configured to be multifunctional, having a first function of EMI mitigation and a second function of thermal management. For example, the composition can be configured to operate at frequencies from about 40 gigahertz (GHz) to about 120 GHz with a return loss of greater than 15 decibels and have a high thermal conductivity (e.g., in the range of about 1 W / mK (watt per meter per Kelvin) to about 10 W / mK). The composition can include about 0.5% or less by volume of carbon nanotubes. The carbon nanotubes can include one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, and / or carbon nanostructures including branched networks of cross-linked carbon nanotube structures. The polymer resin can include a liquid silicone and / or a thermosetting material matrix.

[0033] The method may include incorporating carbon nanotubes into a liquid silicone and / or thermoset matrix formulated such that the composition contains carbon nanotubes in an amount ranging from about 0.1% to about 0.5% by volume.

[0034] The method can include injecting the composition into a mold and molding the composition into a molded part having a pattern of an EMI absorber. The EMI absorber can include rectangular pyramid structures including rectangular bases that protrude outwardly along at least one side of the molded part and are configured so that the rectangular bases of adjacent rectangular pyramid structures contact each other with substantially no gap or spacing between them. Molding the composition into a molded part can include injection molding the composition into a radar bracket.

[0035] Also disclosed herein are exemplary embodiments of films (e.g., multilayer block copolymer films, homogeneous block copolymer films, monolayer block copolymer films, etc.) and patterned materials (e.g., roll-to-roll patternable polymers, etc.) that can have controlled and / or tailored performance (e.g., thermal management, electromagnetic interference (EMI) mitigation, electrical conductivity, thermal conductivity, EMI absorption, magnetic, dielectric, and / or structural performance, etc.). Also disclosed are exemplary embodiments of systems and methods for making such multilayer films, patterned materials, and monolayer / homogeneous films. Also disclosed are exemplary embodiments of thermal management and / or EMI mitigation materials, board-level shielding, and devices. For example, electronic devices (e.g., smartphones, smartwatches, 5G antennas in packages (AIPs), etc.) can include one or more of multilayer films, patterned materials, monolayer / homogeneous films, board-level shielding, and / or thermal management and / or EMI mitigation materials.

[0036] In exemplary embodiments, the material comprises a pattern of structures (e.g., a pyramidal pattern, a hierarchical pattern, a non-pyramidal pattern, a bell-shaped pattern, combinations thereof, etc.) The material may include a filled dielectric, such as polydimethylsiloxane filled with carbon black and / or carbon nanotubes (e.g., single-walled carbon nanotubes, multi-walled carbon nanotubes, and / or carbon nanostructures, etc.), a filled block copolymer system, a filled elastomer system (e.g., cured elastomers, thermoplastic elastomers (TPEs), Santoprene® thermoplastic vulcanizates, etc.), a filled thermoplastic system (e.g., liquid silicone, urethane, polycarbonate, polyamide, polyester, polyolefin, polybutylene terephthalate, thermoplastic vulcanizates, thermoplastic elastomers, polyolefin-containing blends, acrylonitrile butadiene styrene (ABS), polypropylene (PP), polyethylene (PE), etc.), an injection moldable and / or polymer resin filled with single-walled carbon nanotubes, multi-walled carbon nanotubes, and / or carbon nanostructures, etc. The structural patterns may include patterns of pyramidal structures (e.g., rectangular pyramids, pyramidal frustums with rectangular bases, pyramidal structures shown in Figures 1A-1E, etc.), non-pyramidal structures, or a combination of pyramidal and non-pyramidal structures.

[0037] Referring now to the figures, Figures 1A-1E show an exemplary pyramidal pattern 100 for a material (e.g., a film, layer, etc.) according to an exemplary embodiment. Example dimensions in centimeters (cm) are provided for illustrative purposes only. Other exemplary embodiments may include different patterns than those shown in Figures 1A-1E, such as patterns of non-pyramidal structures, structures with different dimensions, structures with different patterns or layouts, combinations of pyramidal and non-pyramidal structures, etc.

[0038] 2A-2E each illustrate steps of an exemplary method 200 for fabricating a pattern (e.g., a pyramidal pattern as shown in FIGS. 1A-1E, a non-pyramidal pattern, a combination thereof, etc.) in a filled dielectric system (e.g., polydimethylsiloxane (PDMS) filled with carbon black and / or carbon nanotubes, a filled block copolymer system, a filled elastomer system, a filled thermoplastic system, an injection-moldable resin filled with carbon nanotubes, a polymer resin filled with carbon nanotubes, etc.) according to an exemplary embodiment. In most cases, the exemplary method includes computer design to model the part, 3D printing or additive manufacturing to create the modeled part, finishing the 3D-printed part for final properties (e.g., gloss, etc.), using the 3D-printed part to create a mold, and using the mold to create a material containing the pattern in the filled dielectric system (e.g., via casting, injection molding, etc.).

[0039] The first step 201 (FIG. 2A) involves computer design to model the part. Computer modeling of the 3D part, such as by using computer-aided design (CAD). The second step 202 (FIG. 2B) involves 3D printing or additive manufacturing (e.g., fused deposition modeling (FDM), stereolithography (SLA), laser direct structuring (LDS), etc.) of the modeled part based on information from the computer design of the modeled part. The 3D printed part (e.g., a 3D printed thermoplastic positive master, etc.) can then undergo post-processing, such as removing excess material, post-curing, applying a surface layer for a matte or glossy finish, etc.

[0040] The third step 203 (FIG. 2C) involves using the 3D-printed part to replicate a mold (e.g., elastomer, etc.). For example, the 3D-printed part can be used to replicate a pattern onto a negative mold in various ways. For example, the 3D-printed part can be used to replicate a pattern onto a negative mold made of polydimethylsiloxane (PDMS) via fused deposition modeling, stereolithography, etc. The negative mold can be surface-treated with an emissive layer (e.g., a self-assembled monolayer, other barrier layer, or release layer, etc.) for easier release, ultraviolet (UV) vitrification, vapor-phase silanization, etc.

[0041] As another example, frontal photopolymerization and polymerizable photoresist may be used to create a PDMS negative mold from, for example, a hard thiol-ene pattern. As a further example, CNC (computer numerical control) milling may be used to create a metal (e.g., aluminum) negative mold. Another example includes a frontal photopolymerization approach using a thiol-ene as an optical adhesive that is cured on the PDMS mold under a UV lamp while on a conveyor belt in a continuous process (e.g., configured to pass under the UV lamp several times during curing). A further example includes replicating a pattern into a thermoset to provide a mold from which a part (e.g., thermoset, thermoplastic, elastomer, etc.) can be further replicated.

[0042] The fourth step 204 (FIG. 2D) involves using the negative mold to create a part made of PDMS and carbon black. For example, this fourth step 204 can be performed after fabricating an inverse PDMS mold (negative pattern) from a 3D-printed master (positive pattern). In this fourth step 204, the negative mold is used as a starting point for fabricating a pattern (e.g., pyramidal pattern, other geometric pattern, etc.) in a filled dielectric, such as carbon black-filled PDMS, carbon nanotube-filled injection-moldable resin, carbon nanotube-filled polymer resin, etc. A mixture of PDMS and carbon black (or other filled dielectric system) can be applied (e.g., poured, etc.) to the negative mold, followed by degassing and oven-curing, after which the PDMS / carbon black part can be removed (e.g., peeled, etc.) from the negative mold.

[0043] A fifth step 205 (FIG. 2E) can include testing the molded PDMS and carbon black parts. For example, the height and width of the pattern created on the molded part can be analyzed. Or, for example, the molded part can undergo reflectivity testing. As another example, the PDMS negative mold can undergo durability testing to determine how many molded parts (e.g., at least 20 filled elastomeric parts) can be produced in a single mold before height and pattern fidelity begin to degrade with multiple parts cast from the mold.

[0044] In alternative exemplary embodiments, other methods may alternatively or additionally be used to create patterned materials in filled dielectric systems. Exemplary methods include roll-to-roll processes, such as roll-to-roll patternable polymer processes for continuous pattern replication, roll-to-roll processes including multiple nozzles for simultaneously dispensing materials onto films, layers, etc. Other exemplary methods include extrusion, curtain coating, 3D printing or additive manufacturing (e.g., fused deposition modeling, stereolithography, laser direct structuring with molding, etc.), frontal photopolymerization using a photomask and / or soft master, CNC (computer numerical control), injection or compression molding (e.g., using a thermally cured mold, etc.), soft molding (e.g., using a pre-molded (crosslinked) PDMS mold, etc.), conveyor belt thermoplastic replication, UV systems using a thermally cured master, thiol-ene using a soft master, inkjet (e.g., inkjet dielectric on metal for isolation, etc.), screen printing, spraying, laser welding of discrete layers (e.g., into different layers and at various depths), laser patterning on polyimide films to allow plating (e.g., plating of FSS elements, etc.), casting, injection molding, rolling / forming processes, integrated parts that include pyramidal faces in their design, etc.

[0045] In an exemplary embodiment, the 3D printed mold insert can be used with a compression or injection molding process. Pattern fabrication can be performed in a vacuum oven. For example, a 3D printed master can be placed on a metal sheet. A flat composite sheet (e.g., carbon black-filled polycaprolactone) created by compression molding can then be placed on the 3D printed master and surrounded by a bracket. A weight (e.g., a metal block) can be placed on top of the composite sheet. A pattern is fabricated into the composite sheet from the negative pattern of the 3D printed master using the gravity of the weight on the composite sheet. The material is heated in an oven and then removed from the oven. The material is cooled before the composite is separated from the 3D printed master.

[0046] In an exemplary embodiment, a roll-to-roll process can be used to create patterned materials in a filled dielectric system. This process can include roll-to-roll self-aligning and self-patterning a block copolymer with sufficient particle content for good or satisfactory performance. A patterned PDMS belt can be used for patterning along with a heated plate, such as an oven tunnel. The patterned PDMS belt can include multiple negatively patterned (e.g., silicone) parts whose edges are bonded or joined to the PDMS. The PDMS can be cured along the joints between the edges of the negatively patterned parts. The patterned PDMS belt is wrapped around rollers. The rollers can be spaced a sufficient distance apart to avoid sagging of the patterned PDMS belt.

[0047] During the roll-to-roll process, a carrier (e.g., an aluminum carrier with a release layer) for the uncured mixture of PDMS and carbon black (or other filled dielectric system) moves across a heated plate. A patterned PDMS belt contacts the uncured mixture of PDMS and carbon black. After a sufficient amount of contact time with the patterned PDMS belt to complete filling of the mold, a process for curing the uncured mixture of PDMS and carbon black can be initiated. The cured PDMS and carbon black part can then be removed (e.g., peeled) from the patterned PDMS belt and carrier.

[0048] In an exemplary embodiment, a stepwise deposition process can be used to provide a pattern along a material (e.g., pyramidal patterns, non-pyramidal patterns, combinations thereof, etc., as shown in Figures 1A-1E.) In this exemplary embodiment, the process can include stepwise deposition of a material (e.g., thermally conductive, electrically conductive, EMI absorbing, magnetic, and / or dielectric material, etc.) onto a functional carrier film. The functional carrier film may include filled dielectric systems such as carbon black-filled polydimethylsiloxane (PDMS), filled block copolymer systems, filled elastomer systems (e.g., cured elastomers, thermoplastic elastomers (TPEs), Santoprene® thermoplastic vulcanizates, etc.), filled thermoplastic systems (e.g., liquid silicones, urethanes, polycarbonates, polyamides, polyesters, polyolefins, polybutylene terephthalate, thermoplastic vulcanizates, thermoplastic elastomers, blends including polyolefins, acrylonitrile butadiene styrene (ABS), polypropylene (PP), polyethylene (PE), etc.), carbon nanotube-filled injection moldable resins, carbon nanotube-filled polymer resins, etc. The functional carrier film may also include Kapton® polyimide film, Mylar® polyester film, thermoplastic films usable in stereolithography (SLA) printing, etc.

[0049] In exemplary embodiments, the material can be deposited or otherwise applied to the functionalized carrier film by spraying, printing, additive manufacturing, etc. For example, the material can be applied onto the functionalized carrier film by laser jet printing a first layer of material (e.g., an electrically and / or thermally conductive ink, etc.) onto the functionalized carrier film. A second layer of the same or different material can be laser jet printed onto the first layer. This can be done as part of a roll-to-roll process with the addition of a laser jet printer.

[0050] In exemplary embodiments, films or layers may be provided with material having different thicknesses or heights thereon to accommodate variations in the height of PCB components. For example, an additive manufacturing process may be used to apply thermally conductive material of different thicknesses along the bottom layer of a multilayer film structure, with thicker and thinner portions of the thermally conductive material disposed on the top surfaces of lower and taller PCB components, respectively, in compressive contact when the multilayer film structure is mounted on the PCB components. As another example, additive manufacturing may be used to apply thermally conductive material along the top surface of a lower PCB component, thereby increasing the overall height of the lower component and the thermally conductive material.

[0051] In exemplary embodiments, the bottom film or layer of the multilayer film structure may be configured to be detachable such that the multilayer film structure can be removed from a PCB and reattached to the PCB, for example, via a pressure sensitive adhesive, adhesive, mechanical attachment, etc. For example, the multilayer film structure may be attached to a PCB, removed therefrom (e.g., to access PCB components, etc.), and reattached without damaging the multilayer film structure (e.g., without cutting, without deformation from stretching, etc.).

[0052] The above process may be used to provide a variety of patterns of different structural shapes (e.g., rectangular pyramids, pyramidal structures, non-pyramidal structures, combinations thereof, etc.), including the exemplary structural patterns shown in Figures 5-15. The structural patterns may also be provided by other suitable processes. For example, the structural patterns may include multilayer films, single-layer films, or homogeneous layers / films with through-thickness domains tailored for the specific performance disclosed herein. Alternatively, for example, the structural patterns may include metamaterials.

[0053] In an exemplary embodiment, a multilayer film (or, more broadly, a multilayer structure) includes multiple block copolymer films or layers having through-thickness domains. Examples of block copolymers include polystyrene-polyethylene block copolymers (e.g., polystyrene-block-poly(ethylene oxide) (PS-b-PEO) and the like), polystyrene-acrylate block copolymers (e.g., polystyrene and poly(methyl methacrylate) (PS-PMMA) and the like), styrene-diene block copolymers (e.g., styrene-butadiene (SB) diblock copolymer, styrene-isoprene diblock copolymer, styrene-butadiene-styrene (SBS) triblock copolymer, styrene-isoprene-styrene (SIS) triblock copolymer, styrene-butadiene (SB) star block copolymer, and the like), hydrogenated styrene-diene block copolymers (e.g., hydrogenated SBS styrene-(ethylene-butylene)-styrene, and the like), segmented block copolymers (e.g., segmented polyester-polyether, segmented polyamide-polyether, and the like), and polyolefins. The block copolymer may include block copolymers, ethylene oxide / propylene oxide block copolymers, organosilicone copolymer systems (e.g., siloxane / polysulfone copolymers, siloxane / polyurethanes, siloxane / polyurea copolymers, siloxane / polyamide copolymers, siloxane / polyimide copolymers, siloxane / polyamide / polyimide copolymers, siloxane / polyester copolymers, siloxane / polycarbonate copolymers, siloxane / polystyrene copolymers, siloxane / epoxide resin networks, etc.), hard block copolymers, other block copolymers, and / or combinations thereof. In an exemplary embodiment, the block copolymer film or layer includes polystyrene-block-poly(ethylene oxide) (PS-b-PEO) and / or polystyrene and poly(methyl methacrylate) (PS-PMMA), although other block copolymers can be used in other exemplary embodiments.

[0054] Particular fillers can be preferentially added to domains, thereby enhancing the properties of those domains of the block copolymer film. In exemplary embodiments disclosed herein, one or more fillers are added to domains of multiple block copolymer films to tailor the domains of the multiple block copolymer films for particular performance (e.g., thermal management, electromagnetic interference (EMI) mitigation, electrical conductivity, thermal conductivity, EMI absorption, magnetic properties, dielectric properties, and / or structural performance).

[0055] Multiple block copolymer films with tailored domains can be assembled (e.g., laminated, stacked, etc.) into multilayer structures (e.g., laminate structures, etc.), which can be fabricated by roll-to-roll processes, spin casting, extrusion, curtain coating, 3D printing, additive manufacturing (e.g., fused deposition modeling (FDM), stereolithography (SLA), laser direct structuring (LDS), etc.), molding, etc.

[0056] In exemplary embodiments, through-thickness domains of individual films or layers can be tailored to have specific electrical, thermal, magnetic, dielectric, and / or structural properties using vertical orientation control and preferential segregation / dispersion of fillers (e.g., functional nanoparticles, nickel, cobalt, boron nitride, coated filler particles, etc.). By controlling the size, shape, and structure of domains within multiple films or layers, the domains can be configured to produce patterns (e.g., macropatterns or hierarchical patterns based on the patterns of individual layers) or gradients (e.g., impedance gradients built across the domains of a multilayer block copolymer film / layer, such as by filler loading).

[0057] Domains can be configured in multiple layers to have different functions, and domains in one layer can be configured to be different from or the same as domains in one or more other layers (e.g., for performance control).

[0058] The multiple films or layers can be configured differently from one another, for example, the films or layers can have different thicknesses, can include different fillers (e.g., different materials, sizes, and / or shapes, etc.), can be made from different base or matrix materials, can have domains of different configurations (e.g., tailored to have different functions, different sizes, different arrangements, etc.).

[0059] For example, a multilayer film structure may include multiple films or layers, at least one or more of which include a different base or matrix material and / or different type of filler than at least one or more of the other films or layers. In this example, the multilayer film structure may include a first film or layer including a first base or matrix material and a first type of filler (e.g., thermally conductive filler, etc.). The multilayer film structure may further include a second film or layer including a second base or matrix material different from the first base or matrix material and a second type of filler different from the first type of filler (e.g., electrically conductive and / or EMI absorbing filler, etc.).

[0060] Alternative exemplary embodiments may include polymer films / layers that are homogeneous or monolayer structures and / or are not isolated block copolymers. For example, a homogeneous or monolayer film structure may include tailored, separated through-thickness domains within the homogeneous or monolayer film structure to have specific electrical, thermal, magnetic, dielectric, and / or structural performance. The vertical orientation control and preferential segregation / dispersion of fillers (e.g., functional nanoparticles, nickel cobalt, boron nitride, coated filler particles, etc.) can be used to separate and tailor the through-thickness domains within the homogeneous or monolayer film structure. By controlling the domain size, shape, and structure within the homogeneous or monolayer film structure, the domains can be configured to generate patterns (e.g., macropatterns or hierarchical patterns based on the patterns of individual layers) or gradients (e.g., impedance gradients built across the domains of individual layers, such as by filler loading). The domains can be configured so that different separated portions of the homogeneous or monolayer film structure have different functions. The domains within the first and second spaced apart portions of the homogeneous or monolayer film structure can be configured to be different from one another (eg, for performance control, etc.) or the same.

[0061] 3 illustrates a multilayer film structure 300 according to an exemplary embodiment embodying one or more aspects of the present disclosure. As shown, the multilayer film structure 300 includes four films or layers 302, 304, 306, and 308, and respective through-thickness domains 310, 312, 314, and 316 in each of the four layers. In alternative embodiments, the multilayer film structure may be configured differently, for example, with more or fewer than four layers, more or fewer through-thickness domains, etc.

[0062] The domains within each layer can be tailored to have specific characteristics, properties, functions, and / or performance (e.g., electrical, thermal, magnetic, dielectric, and / or structural, etc.). By way of example, the domains 310 in the first or top layer 302 can be configured for thermal performance. The domains 312, 314 in the second and third layers 304, 306, respectively, can be configured for EMI mitigation, e.g., conductive, EMI absorbent, magnetic, etc. The domains 316 in the fourth or bottom layer 308 can be configured for dielectric performance.

[0063] The domains of an individual layer can create a pattern tailored or unique to that individual layer. The patterns of the individual layers can collectively define or create a macropattern in the multilayer film structure (e.g., through its thickness, etc.). For example, the domains of one layer may be vertically aligned and / or at least partially overlap with the domains of another layer, and the vertically aligned and / or at least partially overlapping domains within a layer may collectively define pathways (e.g., electrically and / or thermally conductive pathways, vias, columns, etc.) that run vertically through the thickness of the layer.

[0064] In exemplary embodiments, the domains of different layers may include vertically aligned thermally conductive and / or electrically conductive fillers that create vertical, through-thickness conductive paths through the different layers. For example, a thermal path with a relatively high thermal conductivity may be created, which may be high enough to provide good performance even when the multilayer film structure has a relatively high contact resistance. Depending on the contact resistance of the multilayer film structure, a relatively thin, soft, and conformal thermally conductive layer may be added to reduce the contact resistance and improve thermal performance.

[0065] A block copolymer can be used as the base or matrix material 320 for one or more of the four films 302, 304, 306, and 308 shown in Figure 3. For example, polystyrene-block-poly(ethylene oxide) (PS-b-PEO) can be used as the base or matrix material 320 for only one, two, three, or all of the films in the multilayer film structure 300. Alternatively, for example, polystyrene and poly(methyl methacrylate) (PS-PMMA) can be used as the base or matrix material 320 for only one, two, three, or all of the films in the multilayer film structure 300. Another polymer can alternatively be selected that allows for larger domain sizes than those achievable with polystyrene-block-poly(ethylene oxide) (PS-b-PEO) and / or polystyrene and poly(methyl methacrylate) (PS-PMMA).In other embodiments, a different base or matrix material can be used for one or more of the films, such as a polystyrene-polyethylene block copolymer, another polystyrene-acrylate block copolymer, a styrene-diene block copolymer (e.g., styrene-butadiene (SB) diblock copolymer, styrene-isoprene diblock copolymer, styrene-butadiene-styrene (SBS) triblock copolymer, styrene-isoprene-styrene (SIS) triblock copolymer, styrene-butadiene (SB) star block copolymer, etc.), hydrogenated styrene-diene block copolymer (e.g., hydrogenated SBS styrene-(ethylene-butylene)-styrene, etc.), segmented block copolymers ( For example, segmented polyester-polyether, segmented polyamide-polyether, etc.), polyolefin block copolymers, ethylene oxide / propylene oxide block copolymers, organosilicone copolymer systems (e.g., siloxane / polysulfone copolymers, siloxane / polyurethane, siloxane / polyurea copolymers, siloxane / polyamide copolymers, siloxane / polyimide copolymers, siloxane / polyamide / polyimide copolymers, siloxane / polyester copolymers, siloxane / polycarbonate copolymers, siloxane / polystyrene copolymers, siloxane / epoxide resin networks, etc.), hard block copolymers, other block copolymers, and / or combinations thereof.

[0066] A wide variety of fillers can be incorporated into the base or matrix material 320 of the film to adjust, modify, and / or functionally tailor the properties of the resulting film. Fillers can include functional nanoparticles, conductive fillers, thermally conductive fillers, EMI or microwave absorbing fillers, magnetic fillers, dielectric fillers, coated fillers, combinations thereof, etc. Fillers may be added to and mixed with bulk materials including the base or matrix material to provide a mixture of filler and base or matrix material. Examples of fillers include carbon black, boron nitride, nickel cobalt, air-filled microballoons, air-filled microbubbles, air-filled microspheres, carbonyl iron, iron silicide, 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, ferrite, magnetic alloys, magnetic powders, magnetic flakes, magnetic particles, nickel-based alloys and powders, chromium alloys, aluminum oxide, copper, zinc oxide, alumina, aluminum, graphite, ceramics, silicon carbide, manganese zinc, glass fibers, carbon nanotubes (e.g., single-walled carbon nanotubes, multi-walled carbon nanotubes, and / or carbon nanostructures), combinations thereof, etc. The filler may comprise one or more of granules, spheroids, microspheres, ellipsoids, irregular spheroids, strands, flakes, powders, nanotubes, and / or combinations of any or all of these shapes. Additionally, exemplary embodiments may also include different grades (eg, different sizes, different purities, different shapes, etc.) of the same (or different) fillers.

[0067] In an exemplary embodiment, the films of the multilayer film structure (such as, for example, films 302, 304, 306, and / or 308 of the multilayer film structure 300 shown in FIG. 3) can be manufactured by casting, film extrusion, lamination, or the like.

[0068] FIG. 4 illustrates an exemplary embodiment of a multilayer film structure 400 (e.g., a four-layer film structure, etc.) according to an exemplary embodiment embodying one or more aspects of the present disclosure. In this exemplary embodiment, the filler density per layer increases in the direction from the top layer 402 to the bottom layer 408, as indicated by the arrows. Thus, the bottom layer 408 has the highest filler density, and the top layer 402 has the lowest filler density. With respect to the two intermediate layers 404, 406 between the top and bottom layers 402, 408, the lower intermediate layer 406 has a higher filler density than the upper intermediate layer 406. The overall thickness or height dimension of the multilayer film structure 400 may be approximately 1.7 millimeters (mm). However, this 1.7 mm dimension is provided for illustrative purposes only, as in other embodiments, the multilayer film structure may be thicker or thinner than 1.7 mm. Also, although the multilayer film structure 400 shown in FIG. 4 includes four layers 402, 404, 406, 408, other exemplary embodiments may include multilayer film structures with more or less than four layers.

[0069] In exemplary embodiments, the multilayer film structure may include films having functionality in separate, distinct regions, such as electrical, thermal, absorptive, magnetic, dielectric, and / or structural functionality. For example, the multilayer film structure may include films configured to have thermal management functionality, EMI shielding functionality, and EMI absorption functionality in separate, distinct regions of the multilayer film structure.

[0070] The multilayer film structure may have different fillers within the layers or films for different performance, effects, etc. For example, the multilayer film structure may have different fillers in different layers, which may be operable to mitigate EMI (e.g., absorb high frequency EMI) in a manner similar to the EMI mitigation provided by the pyramidal or non-pyramidal structures shown in Figures 5-15 and 21 and described herein.

[0071] In exemplary embodiments, the multilayer film structure and / or patterned material may be provided with a backing via a metallization process, lamination, tape casting, vacuum deposition, other suitable processes, combinations thereof, etc. The backing may include one or more metals (e.g., aluminum, copper, etc.), coated metals (e.g., nickel-coated aluminum, etc.), clad metals, metallized polymer films / plastics, aluminized Mylar® biaxially oriented polyethylene terephthalate (BoPET), other backing materials, combinations thereof, etc. For example, a backing including a metal (e.g., aluminum, copper, etc.) may be provided (e.g., via a metallization process, etc.) along an outer exposed surface of the multilayer film structure, such as along the bottom surface of multilayer film structures 300 and / or 400 shown in FIG. 3 or FIG. 4, respectively. Alternatively, a backing comprising, for example, a metal (e.g., aluminum, copper, etc.) may be provided (e.g., via a metallization process, etc.) along the bottom surface of a patterned material, such as the bottom surfaces of patterned materials 500, 600, and / or 2100 shown in Figures 5, 6, or 21, respectively.

[0072] In exemplary embodiments, the multilayer film structure and / or patterned material may have a relatively high contact resistance, depending on the materials used, or, for example, the multilayer film structure and / or patterned material may include one or more thermally conductive pillars or columns (broadly speaking, portions) with very high thermal conductivity to help offset and / or overcome the relatively high contact resistance.

[0073] In exemplary embodiments, one or more thermal interface materials, heat spreaders, thermoelectric modules, etc. may be used in conjunction with the multilayer film structure and / or patterned materials. For example, a heat spreader (e.g., a graphite heat spreader, etc.) may be disposed along the multilayer film structure (e.g., laminated, sealed between films by laser welding, etc.). Alternatively, for example, a thermoelectric module may be disposed along the multilayer film structure.

[0074] As another example, the thermal interface material may be disposed along the top and / or bottom surfaces of the multilayer film structure. In this latter example, the thermal interface material may help accommodate variations in the height of shorter and taller PCB components. For example, the thermal interface material may be disposed along the bottom surface of the multilayer film structure such that when the multilayer film structure is installed on the PCB component, the thermal interface material is disposed on and in compressive contact with the top surface of the PCB component. The thermal interface material may also be disposed along the top surface of the multilayer film structure such that the thermal interface material is in compressive contact with a heat spreader (e.g., an external case or device housing, etc.). Examples of thermal interface materials include thermal gap fillers, thermal phase change materials, thermally conductive EMI absorbers or thermal / EMI hybrid absorbers, thermal grease, thermal paste, thermal putty, dispensable thermal interface materials, thermal pads, etc.

[0075] Exemplary embodiments may include one or more radiating antenna elements defined or created by domains in one or more layers or films of a multilayer film structure, a homogeneous film structure, or a monolayer film structure. Exemplary embodiments may include film structures (e.g., multilayer film structures, homogeneous film structures, monolayer film structures, etc.) including one or more layers or films configured to provide (e.g., have domains tailored therefor) environmental protection (e.g., a vapor or oxygen barrier, etc.). Exemplary embodiments may include one or more waveguides defined or created by domains in one or more layers or films of a multilayer film structure, a homogeneous film structure, or a monolayer film structure. Thus, exemplary embodiments may include multilayer film structures having multiple layers or films with domains configured to provide one or more radiating antenna elements, one or more waveguides, EMI mitigation, thermal management, dielectric properties, structure, and / or environmental protection, etc. Exemplary embodiments may also include homogeneous or monolayer film structures having single or discrete layers or films with domains configured to provide one or more radiating antenna elements, one or more waveguides, EMI mitigation, thermal management, dielectric properties, structure, and / or environmental protection, etc.

[0076] 5-15 and 21 illustrate exemplary structures (e.g., pyramidal structures, non-pyramidal structures, etc.) configured for EMI mitigation (e.g., absorbing high frequencies, etc.) according to exemplary embodiments embodying one or more aspects of the present disclosure. In exemplary embodiments (e.g., FIGS. 7-15, etc.), the structures may be disposed (e.g., glued, etc.) along a portion of a board-level shield (BLS) and protrude outward. For example, the structures may protrude outward from the interior and / or exterior surfaces of a top, cover, lid, sidewall, fence, frame, etc. of the BLS. The BLS may be configured (e.g., formed of metal, molded, sized, etc.) to mitigate (e.g., block, reflect, etc.) low-frequency EMI. The structures may be configured (e.g., formed of EMI-absorbing material, molded, sized, etc.) to mitigate (e.g., absorb, etc.) high-frequency EMI.

[0077] FIGS. 5-15 and 21 illustrate exemplary pyramid structures that are rectangular pyramids. The rectangular bases of adjacent pyramids can touch each other with substantially no gaps or spacing between the rectangular bases. This helps avoid reflectivity that may occur if there were gaps between the rectangular bases of the pyramid structures. Other exemplary embodiments may include non-pyramid structures that taper or decrease in width (e.g., generally smoothly curved, etc.) from the top (e.g., apex) to the base. For example, FIGS. 14 and 15 illustrate exemplary embodiments including non-pyramid structures 1400 and 1500, respectively. Alternative exemplary embodiments may include structures having non-rectangular bases, such as hexagonal bases, triangular bases, etc. Thus, the present disclosure should not be limited solely to rectangular pyramid structures, as other exemplary embodiments may include structures having different three-dimensional geometries.

[0078] In exemplary embodiments, the sides of a structure may not be perfectly smooth or define a perfectly straight line from top to bottom. For example, when viewed under high magnification, the sides may appear to have a stepped configuration. However, the sides of a pyramidal or non-pyramidal structure are preferably relatively smooth (e.g., free of significant steps) to reduce or avoid reflections of EMI incident on the structure. Additionally, the structure may be configured to have varying slopes or tapers along its sides (e.g., at least two or more slopes). For example, a pyramidal structure may have a relatively gradual taper from the base to a central portion, a more rapid taper from the central portion to the top, and a smaller taper from there to the top of the structure.

[0079] The structures shown in Figures 5-15 and 21 can be fabricated by the processes shown in Figures 2A-2E and described above. The structures shown in Figures 5-15 and 21 can include filled dielectrics, such as carbon black-filled polydimethylsiloxane (PDMS), filled block copolymer systems, filled elastomer systems, filled thermoplastic systems, etc. Alternatively, the structures shown in Figures 5-15 and 21 can be fabricated with other materials and / or by other suitable processes (e.g., stepwise deposition of materials onto a functionalized carrier film, etc.). The structures can include one or more first structures along a first layer and one or more second structures along a second layer. The first and second structures can be configured differently, for example, with different shapes, different heights, made of different materials, etc.

[0080] In exemplary embodiments, the configuration of the structures (e.g., height, shape, location, etc.) may be non-randomized or randomized (e.g., via a computerized randomization process, etc.). Randomizing the height of the structures along the interior of the BLS may help reduce or avoid cavity resonances below the BLS. Exemplary embodiments may include rectangular pyramid structures with the same sized base, but one or more rectangular pyramid structures may have a different height than one or more other rectangular pyramid structures. For example, taller pyramids may be located along the edge or perimeter, while shorter pyramids may be located in the center or interior, spaced inward from the edge or perimeter.

[0081] Using structures with different heights can accommodate variations in the height of shorter and taller PCB components. For example, taller and shorter structures can be positioned along the inside surface of a BLS cover or lid such that when the BLS is installed on the PCB components, the taller and shorter structures are positioned approximately above the shorter and taller PCB components, respectively. Different structure heights can also help avoid or reduce cavity resonances below the BLS.

[0082] 5 illustrates a filled dielectric 538 including a pyramidal structure 540 according to an exemplary embodiment 500 embodying one or more aspects of the present disclosure. As shown, the pyramidal structure 540 includes air-filled particles 542 (e.g., air-filled microballoons, air-filled microbubbles, air-filled microspheres, etc.) within the filled dielectric 538. The air-filled particles 542 add air to the pyramidal structure 540, which lowers (e.g., controllably lowers) the dielectric constant. The air-filled particles 542 can be used internally to approximate the dielectric constant of the pyramidal structure 540 to that of a foam and / or to approximate the dielectric properties of a foam.

[0083] In addition to or instead of loading or filling with air-filled particles 542, pyramidal and / or non-pyramidal structures can be covered or coated with a polymer containing air-filled particles (e.g., air-filled microballoons, air-filled microbubbles, air-filled microspheres, hollow glass, plastic, and / or ceramic microspheres, other microspheres, etc.) in other exemplary embodiments. For example, exemplary embodiments may include pyramidal structures coated or covered with a microballoon-filled polymer, e.g., for environmental resistance, etc. In this example, the microballoon-filled polymer may cover the pyramidal structures and define a flattening layer for filling the spaces between the pyramidal structures. The inverted pyramidal structures of the flattened microballoon-filled polymer layer may interlock or fit with the pyramidal structures such that the combination of the pyramidal structures and the flattened microballoon-filled polymer layer has a generally flat, sheet-like configuration. The flattened microballoon-filled polymer layer may be operable to inhibit or prevent dirt and / or other debris from filling the spaces, pores, openings, gaps, etc. between the pyramidal structures. By way of example, the microballoon-filled polymer can include a low dielectric loss, low dielectric constant (e.g., less than 10, 1-2, less than 1, etc.) material, such as a low-K, low dielectric loss, low dielectric constant material from Laird, including thermosetting plastics or silicone rubber and hollow glass microspheres, etc. Alternatively, other materials (e.g., including materials that are not low dielectric loss, low dielectric constant materials and / or do not include hollow glass microspheres) can be used to define the planarization layer and / or to cover or coat the pyramidal and / or non-pyramidal structures to inhibit or prevent dirt and / or other debris from filling the spaces, pores, openings, gaps, etc. between the pyramidal and / or non-pyramidal structures in exemplary embodiments. Accordingly, aspects of the present disclosure include methods of inhibiting or preventing dirt and / or other debris from filling the spaces, pores, openings, gaps, etc. between the pyramidal and / or non-pyramidal structures disclosed herein.

[0084] 6 illustrates an EMI absorber 644 including a pyramidal structure 640, a planarization layer 646, and a multilayer frequency selective surface (FSS) structure 648, according to an exemplary embodiment 600 embodying one or more aspects of the present disclosure. As shown, the EMI absorber 644 and pyramidal structure 640 may include carbon black-filled polydimethylsiloxane (PDMS), a filled block copolymer system, a filled elastomer system (e.g., cured elastomer, thermoplastic elastomer (TPE), Santoprene® thermoplastic vulcanizate, etc.), a filled thermoplastic system (e.g., polyamide, acrylonitrile butadiene styrene (ABS), polypropylene (PP), polyethylene (PE), etc.), an injection moldable resin filled with carbon nanotubes, a polymer resin filled with carbon nanotubes, etc.

[0085] 6, the planarizing layer 646 includes or defines downwardly protruding inverted pyramidal structures 650 to fill the spaces between the upwardly protruding pyramidal structures 640 of the EMI absorber 644. The inverted pyramidal structures 650 of the planarizing layer 646 can interlock or fit with the pyramidal structures 640 such that the combination of the EMI absorber 644 and the planarizing layer 646 has a generally flat, sheet-like configuration.

[0086] The planarization layer 646 may include a dielectric material (e.g., a dielectrically graded dielectric for impedance matching, a uniform dielectric planarization layer, etc.), a thermally conductive material, an electrically conductive material, etc. The planarization layer 646 strengthens the pyramidal structures, protects the pyramidal structures 640 from breakage, provides adhesion, provides stiffness or structure for mounting purposes and / or adjusting the modulus of elasticity, and / or helps inhibit or prevent dirt and / or other debris from filling the spaces, pores, openings, gaps, etc. between the pyramidal structures 640. The planarization layer 646 may be provided in different thicknesses to accommodate variations in height of lower and higher components such as PCBs, SIPs, etc.

[0087] In exemplary embodiments in which the planarization layer is conductive, one or more dielectric materials (e.g., thin dielectric layers, etc.) can be provided along exposed outer surface portions of the planarization layer to avoid shorting adjacent device components due to the conductive planarization layer. As another example, the dielectric material can be embedded in a thermal interface material (TIM) when the TIM is used as the planarization layer (e.g., injection molded, etc.). The planarization layers described herein (e.g., 646 shown in FIG. 6) can also be used in other exemplary embodiments, including EMI absorbing structures (e.g., FIGS. 5, 7-15, and 21).

[0088] The multilayer frequency selective surface (FSS) structure 648 shown in FIG. 6 includes multiple (e.g., three) layers of FSS elements 652. Alternative embodiments may include FSS structures having more or fewer layers than three, e.g., a single layer, two layers, four layers, etc. For example, FIG. 19 shows an example embodiment 1900 of a multilayer FSS structure 1948 including four layers 1902, 1904, 1906, 1908 of FSS elements 1952. Alternatively, for example, example embodiments may include a single layer of FSS elements, multiple coplanar rings in a single plane, a conductive metamaterial in a pattern on a dielectric along the underside of the BLS and / or along the ground plane, etc. Thus, the present disclosure should not be limited to only three- or four-layer FSS structures.

[0089] 6 and 19, layers of the multilayer frequency selective surface (FSS) structures 648, 1948 include patterns of FSS elements 652, 1952, respectively. The FSS elements may include conductive materials, EMI absorbing materials, and / or metamaterials.

[0090] In the exemplary embodiments of Figures 6 and 19, the FSS elements 652, 1952 include annular elements (e.g., circular rings, generally circular annular elements, etc.) with open areas or openings. By way of example, the open areas or openings may include perforations or holes die-cut into a layer (e.g., laser patterned on a layer) for airflow before or after the FSS elements are applied. Alternatively, for example, the open areas or openings may be formed by etching or washing cured / uncured polymer from the FSS elements. As another example, the FSS layer may be fabricated using a mold configured to create the open areas or openings.

[0091] As shown in FIG. 6 , multiple layers of the multilayer FSS structure 648 can be in a stacked arrangement (e.g., a laminated structure) such that the FSS elements 652 of each layer overlap and are vertically aligned with the FSS elements 652 of the other layers. Therefore, the openings or open areas of each layer are vertically aligned with the openings or open areas of the other layers. Because air and / or liquid may flow through the vertically aligned openings or open areas, the FSS elements 652 can be used to mitigate EMI without completely blocking the flow of air and / or liquid through the multilayer FSS structure. Alternative embodiments can include multilayer FSS structures (e.g., 1948 shown in FIG. 19 ) configured to include FSS elements where none of the FSS elements overlap or are vertically aligned with other FSS elements and / or where none of the FSS elements are configured with any openings or open areas.

[0092] In exemplary embodiments, the films or layers of the multilayer FSS structure (e.g., 648 (FIG. 6), 1948 (FIG. 19), etc.) may comprise block copolymers, polydimethylsiloxane (PDMS), thermoplastic films prepared by the methods disclosed herein, etc.

[0093] Multilayer FSS structures (e.g., 648 (FIG. 6), 1948 (FIG. 19), etc.) can include multiple films or layers along with FSS elements provided by the methods disclosed herein. By way of example, an FSS structure can include a copper-containing FSS element and a film or layer including Mylar® biaxially oriented polyethylene terephthalate (BoPET). In this example, the copper pattern of the FSS element can be etched into the Mylar® BoPET film or layer using an FR4 / PCB manufacturing process. As another example, the FSS element can be provided along the film or layer by 3D printing or additive manufacturing (e.g., fused deposition modeling, stereolithography, laser direct structuring with molding, etc.). Alternatively, for example, the FSS element can include a conductive ink (e.g., a silver and / or copper-containing ink) inkjet-printed along the film or layer (e.g., via a microjet inkjet printer, etc.). As yet another example, an impregnated plastic film can include portions that become conductive after laser irradiation, and these conductive portions define the conductive FSS elements. As a further example, films or layers of a multi-layer FSS structure can be impregnated, embedded, and / or printed with one or more materials to create conductive regions that define a pattern (e.g., rings, etc.) on the FSS surface. Other methods can also be used to provide FSS elements in a film or layer.

[0094] Multiple films having conductive FSS elements can be assembled together (e.g., stacked, laminated, etc.) to form a multi-layer FSS structure. The FSS elements may be backed by an absorber to lower the frequency of the absorber.

[0095] In exemplary embodiments, an FSS structure (e.g., 648 (FIG. 6), 1948 (FIG. 19), etc.) may be operable to block energy over one or more specific frequencies or frequency ranges, while simultaneously allowing one or more different specific frequencies or frequency ranges to pass. In this case, the FSS structure may be used as a single-band or multi-band bandpass waveguide and / or EMI mitigation structure.

[0096] In an exemplary embodiment, one or more FSS elements may have a different shape and / or size than one or more other FSS elements. For example, another exemplary embodiment may include an FSS structure having FSS ring elements of different thicknesses and / or different radii.

[0097] In exemplary embodiments, the layers of the multi-layer FSS structure can be any shape (e.g., rectangular, circular, triangular, etc.) and / or size, for example, to operate at multiple frequencies and / or operate over a wider bandwidth. In operation, the FSS structure can reflect, absorb, block, and / or redirect signals at grazing incidence (90 degrees off from normal) to stop the energy.

[0098] FIG. 7 illustrates a pyramidal structure 740 along a portion (e.g., top, cover, lid, sidewall, fence, frame, etc.) of a board-level shield (BLS) 754 according to an exemplary embodiment 700 embodying one or more aspects of the present disclosure. In the example illustrated in FIG. 7 , the pyramidal structure 740 is a rectangular pyramid with a rectangular base. The pyramidal structure 740 may be disposed along the top surface and / or sidewall of the BLS and may protrude / extend outward from the outer surface and / or inward from the inner surface (e.g., FIGS. 11, 12, and 13). The pyramidal structure 740 may be configured to mitigate (e.g., absorb, etc.) high-frequency EMI. The BLS 754 may be configured (e.g., formed of metal) to mitigate (e.g., block) low-frequency EMI.

[0099] FIG. 8 illustrates pyramidal structures 840 along a portion (e.g., top, cover, lid, sidewall, fence, frame, etc.) of a board-level shield (BLS) 854 according to an exemplary embodiment 800 embodying one or more aspects of the present disclosure. In the example illustrated in FIG. 8 , the pyramidal structures 840 are rectangular pyramids with rectangular bases. In this example, the pyramidal structures 840 are not all the same size. For example, the two inner pyramidal structures are shown with different heights, both of which are lower than the heights of the two outer pyramidal structures. The pyramidal structures 840 can be configured to mitigate (e.g., absorb) high-frequency EMI. The BLS 854 can be configured (e.g., formed of metal) to mitigate (e.g., block) low-frequency EMI.

[0100] FIG. 9 illustrates a pyramidal structure 940 along a portion (e.g., a top, cover, lid, sidewall, fence, frame, etc.) of a board-level shield (BLS) 954 according to an exemplary embodiment 900 embodying one or more aspects of the present disclosure. In the example illustrated in FIG. 9 , the pyramidal structure includes air-filled microballoons, microspheres, microbubbles, etc. 942 therein. The added air by the microballoons, microspheres, or microbubbles 942 reduces the dielectric constant of the pyramidal structure 940. The pyramidal structure 940 is a rectangular pyramid with a rectangular base. The pyramidal structure 940 can be configured to mitigate (e.g., absorb) high-frequency EMI. The BLS 954 can be configured (e.g., formed of metal) to mitigate (e.g., block) low-frequency EMI.

[0101] FIG. 10 illustrates pyramidal structures 1040 along a portion (e.g., top, cover, lid, sidewall, fence, frame, etc.) of a board-level shield (BLS) 1054 according to an exemplary embodiment 1000 embodying one or more aspects of the present disclosure. In the example illustrated in FIG. 10 , at least one or more of the pyramidal structures 1040 are multilayered. As illustrated in FIG. 10 , the filler density per layer of the multilayer pyramidal structure 1040 increases from the top layer to the bottom layer, as indicated by the arrows. Thus, the bottom layer has the highest filler density, and the top layer has the lowest filler density. With respect to the two intermediate layers between the top and bottom layers, the lower intermediate layer has a higher filler density than the upper intermediate layer. The pyramidal structure 1040 can be configured to mitigate (e.g., absorb) high-frequency EMI. The BLS 1054 can be configured (e.g., formed of metal) to mitigate (e.g., block) low-frequency EMI.

[0102] By way of example only, the multi-layer pyramidal structure may have an overall height of about 2 mm or less and layers that are about 100 μm thick. However, these dimensions are provided for illustrative purposes only, as the multi-layer pyramidal structure may have different overall heights and / or layers of different thicknesses. Also, while the pyramidal structure 100 shown in FIG. 10 includes four layers, other exemplary embodiments may include multi-layer pyramidal structures with more or fewer than four layers. Various gradients of filler material may be used in the multi-layer film absorber structure (e.g., multi-layer pyramidal structure 1040, etc.). The multi-layer film absorber structure (e.g., multi-layer pyramidal structure 1040, etc.) may be flexible enough to be wrapped around at least a portion of a shield, device, etc.

[0103] 11, 12, and 13 illustrate pyramidal structures 1140, 1240, and 1340 along the top and sidewalls of board-level shields (BLSs) 1154, 1254, and 1354, respectively, according to exemplary embodiments 1100, 1200, and 1300 embodying one or more aspects of the present disclosure. The BLSs are typically mounted on integrated circuits (ICs) (broadly, components or heat sources) on a PCB (broadly, a substrate). The pyramidal structures can be configured to mitigate (e.g., absorb) high-frequency EMI. The BLSs can be configured (e.g., formed of metal) to mitigate (e.g., block) low-frequency EMI.

[0104] In the exemplary embodiment 1100 shown in FIG. 11, the pyramidal structures 1140 are shown protruding inward from the inner surfaces of the BLS top 1156 and BLS sidewalls 1158 generally in a direction toward the integrated circuit 1160 on the PCB 1162.

[0105] In the exemplary embodiment 1200 shown in FIG. 12, pyramidal structures 1240 are shown protruding outward from the outer surfaces of the BLS top 1256 and BLS sidewalls 1258 generally in a direction away from the integrated circuit 1260 on the PCB 1262.

[0106] In the exemplary embodiment 1300 shown in FIG. 13, the pyramidal structure 1340 is shown protruding inward and outward in opposite directions along both the inner and outer surfaces of the BLS top 1356 and BLS sidewalls 1358 relative to the BLS 1354 and integrated circuit 1360 on the PCB 1362.

[0107] 14 illustrates pyramidal structures 1440 and non-pyramidal structures 1464 along a portion (e.g., top, cover, lid, sidewall, fence, frame, etc.) of a board-level shield (BLS) 1454 according to an exemplary embodiment 1400 embodying one or more aspects of the present disclosure. The pyramidal structures 1440, 1464 may be configured to mitigate (e.g., absorb, etc.) high-frequency EMI. The BLS 1454 may be configured (e.g., formed of metal) to mitigate (e.g., block) low-frequency EMI. As shown in FIG. 14 , the non-pyramidal structures 1464 have various slopes or tapers along their sides.

[0108] 15 illustrates a structure 1564 along a portion (e.g., a top, cover, lid, sidewall, fence, frame, etc.) of a board-level shield (BLS) 1554 according to an example embodiment 1500 embodying one or more aspects of the present disclosure. The structure 1564 may be configured to mitigate (e.g., absorb, etc.) high-frequency EMI. The BLS 1554 may be configured (e.g., formed of metal) to mitigate (e.g., block) low-frequency EMI.

[0109] 15, each overall structure 1564 is generally upright and extends approximately perpendicular to the portion of the BLS 1554. Each structure 1564 includes pyramids 1566 along both sides, which extend generally outward from the structure 1564 in a direction approximately parallel to the BLS portion. By having pyramids 1566 along both sides of the structure 1564, the double-sided structure 1564 shown in FIG. 15 may have improved deflection and reduced contact resistance.

[0110] In exemplary embodiments, EMI absorbing protruding structures (e.g., as shown in Figures 5-15 and 21) may be disposed (e.g., adhered) along one or more exposed and / or flat surfaces. In such embodiments, an inert, non-functional material (e.g., a protective coating, etc.) may be applied (e.g., a coating, etc.) over the EMI absorbing protruding structures. The inert, non-functional material may be configured to protect the EMI absorbing protruding structures from deformation (and performance degradation) and / or allow the EMI absorbing protruding structures to be pressed against the surface without interfering with (e.g., significantly degrading) the function or performance of the EMI absorbing protruding structures.

[0111] An exemplary embodiment includes a method for adhering an EMI absorbing protruding structure to a surface. In this exemplary embodiment, the method may include applying a protective coating over the three-dimensional shape of the EMI absorbing protruding structure. The method may further include applying a compressive force to the protective coating to ensure high bond strength (or PSA adhesion) to the surface. The protective coating may be removable and / or inert (e.g., dielectric, non-absorbing, etc.).

[0112] Also disclosed herein are exemplary embodiments of device components that include (e.g., integrally include, are made of, etc.) the multilayer film structures, patterned materials, metamaterials, and / or functional films. In exemplary embodiments, the multilayer film structures, patterned materials, metamaterials, and / or functional films may be incorporated into and / or used as device components such as external cases, back covers, midplates, screen plates, inner plates, device skins, interposers, IC packaging, etc. In such embodiments, the device components may retain their original functionality but may also have additional functionality (e.g., EMI mitigation, thermal management, dielectric, magnetic, and / or structural, etc.) provided by the multilayer film structures, patterned materials, metamaterials, and / or functional films. By way of example, the multilayer film structures, patterned materials, metamaterials, and / or functional films may be incorporated into and / or used as device cases or skins for smartphones, gaming system consoles, smartwatches, 5G antennas in packages (AIPs), etc.

[0113] In exemplary embodiments, multilayer film structures, patterned materials, metamaterials, and / or functional films can be used to transfer heat from one or more hotter portions or regions of a device (e.g., PCB components, etc.) to one or more cooler portions or regions (e.g., other PCB components, unused portions of a PCB, etc.). By considering the entire device for thermal management purposes rather than treating individual components individually and transferring heat on a single component basis, exemplary embodiments can enable more uniform device temperatures and improved device thermal performance, even when individual components are heated by transferring heat from other components. Thus, exemplary embodiments can include using other portions of an electronic device as heat sinks so that heat is transferred from one component to another component or unused portions of a PCB. For example, an interior panel of an electronic device can include multilayer film structures, patterned materials, metamaterials, and / or functional films used to provide thermal management. The multilayer film structure, patterned material, metamaterial, and / or functional film of the inner plate can draw waste heat from one or more regions and transfer / diffuse the waste heat to one or more other regions, thereby heating and increasing the temperature of those one or more other regions of the electronic device, resulting in a more uniform temperature of the device and more uniform dissipation of heat.

[0114] 16 illustrates an outer device case 1668 including a multilayer film structure (e.g., a four-layer film structure, etc.) and / or a metamaterial 1670 according to an exemplary embodiment 1600 embodying one or more aspects of the present disclosure. In the exemplary embodiment 1600 illustrated in FIG. 16 , the outer device case 1668 includes four layers 1602, 1604, 1606, 1608, which may be configured to provide one or more of an electrical conductor 1672, a waveguide 1674, an EMI absorber 1676, a thermal interface material (TIM) 1678, and a dielectric 1680.

[0115] The waveguide 1674 provided by the multilayer film structure and / or metamaterial 1670 may be operable to guide waves from a PCB component 1681 on the PCB 1662. The thermal interface material 1678 provided by the multilayer film structure and / or metamaterial 1670 may be operable to establish a thermally conductive heat path from the PCB component 1682 to the outside of the outer device case 1668.

[0116] The multilayer film structure and / or metamaterial 1670 may be configured to allow desired signals to pass therethrough (e.g., bandpass, etc.) while rejecting and preventing other undesired signals from passing therethrough (e.g., bandstop, etc.) at the enclosure or external device level. The multilayer film structure and / or metamaterial 1670 may be used to mitigate EMI via directional signal steering at the outer device case 1668.

[0117] The outer device case 1668 may also, or alternatively, include an FSS structure (e.g., 648 (FIG. 6), 1948 (FIG. 19), etc.) within or along portions of the outer device case 1668. For example, a conductive metamaterial in a pattern may be disposed along the inner surface of the outer device case 1668.

[0118] Thus, exemplary embodiments disclosed herein may include an outer device case 1668 that is multifunctional by retaining its original function as an outer device case. However, the outer device case 1668 may also include additional functionality, such as functionality related to a waveguide 1674 and a thermal interface material 1678 being provided by the multilayer film structure and / or metamaterial 1670. In the embodiment shown in FIG. 16 , the outer device case 1668 includes four layers 1602, 1604, 1606, 1608, although other exemplary embodiments may include an outer device case with more or less than four layers.

[0119] 17 illustrates an interposer 1768 including a multilayer film structure (e.g., a four-layer film structure, etc.) and / or a metamaterial 1770 according to an exemplary embodiment 1700 embodying one or more aspects of the present disclosure. In the exemplary embodiment 1700 illustrated in FIG. 17, the multilayer film structure and / or metamaterial interposer 1770 is disposed or sandwiched between two PCBs 1762 and 1763.

[0120] The multilayer film structure and / or metamaterial interposer 1770 may be configured to provide one or more of electrical conductors 1772, waveguides 1774, EMI absorbers 1776, thermal interface materials (TIM) 1778, and dielectrics 1780 interposed between the two lower and upper PCBs 1762, 1763. The multilayer film structure and / or metamaterial interposer 1770 may be selectively functional structures to, for example, connect the two PCBs in the sandwich, make electrical interconnections, provide EMI shielding, and / or provide thermal conduction paths, etc. The multilayer film structure and / or metamaterial interposer 1770 may include portions with a relatively high dielectric constant such that the two PCBs 1762, 1763 are capacitively coupled via the interposer portions with a high dielectric constant.

[0121] In an exemplary embodiment, an interposer is provided to connect two PCBs or SIPs to a component via molding (e.g., injection molding, etc.) with functional block copolymer electrical connection traces between the SIPs. In the exemplary embodiment shown in Figure 17, the interposer 1768 includes four layers 1702, 1704, 1706, 1708, although other exemplary embodiments may include interposers with more or less than four layers.

[0122] The interposer 1768 can be configured to allow interconnection between the PCBs 1762, 1763 as needed while also having improved EMI characteristics. The interposer 1762, 1763 can be positionable between two PCBs 1762, 1763, each including at least one component 1781, 1782, 1783, 1784. The interposer 1768 can include a block copolymer of at least two polymers and one or more fillers, as disclosed herein. The interposer 1768 can include at least one electrical trace passing through it, providing at least one electrical connection between at least one component on one circuit board and at least one component on the other circuit board. For example, the interposer 1768 shown in FIG. 17 can provide electrical connections between PCB components 1781, 1782 on a lower PCB 1762 and corresponding PCB components 1783, 1784 on an upper PCB 1763.

[0123] Exemplary embodiments may include patterning functionality in a multilayer film structure to match the layout of components on two or more PCBs. When the PCBs are sandwiched together, the patterned multilayer film structure may provide electrical interconnections and other functions between the components on the PCBs. In exemplary embodiments, patterned films may be created to provide electrical interconnections for SIPs (system-in-packages). In exemplary embodiments, multilayer film structures including block copolymer films may be used as substrate materials for PCBs.

[0124] 18 illustrates integrated circuit (IC) packaging 1868 of an IC die 1881 including a multilayer film structure and / or metamaterial 1870 according to an exemplary embodiment 1800 embodying one or more aspects of the present disclosure. As shown in FIG. 18 , the multilayer film structure and / or metamaterial 1870 can be configured to provide one or more of electrical conductors / interconnects 1872, waveguides 1874, EMI absorbers 1876, thermal interface materials (TIM) 1878, and dielectrics 1880.

[0125] The multilayer film structure and / or metamaterial 1870 may be configured to guide energy or electromagnetic radiation, etc. The multilayer film structure and / or metamaterial IC packaging may be a selectively functional configuration, such as a partial EMI shield, a partial TIM, a partial EMI absorber, a partial waveguide, and / or a partial electrical connector, etc. The multilayer film structure and / or metamaterial 1870 may be configured to provide a 3D structure (e.g., an IC packaging substrate, etc.) including waveguide or coaxial structures and / or interconnects that are vertical, multi-level, etc. In the embodiment shown in FIG. 18 , the IC packaging 1868 includes four layers 1802, 1804, 1806, 1808, although other exemplary embodiments may include IC packaging with more or less than four layers.

[0126] 20 illustrates a metamaterial TIM 2085 disposed within a device (e.g., a smartphone, etc.) according to an exemplary embodiment 2000 embodying one or more aspects of the present disclosure. As shown in FIG. 20 , the metamaterial TIM 2085 is disposed (e.g., compressed and sandwiched, etc.) between an outer device case / heat spreader 2086 and a PCB 2062 including an array 2087 of antenna elements 2088. In this exemplary embodiment, the metamaterial TIM 2085 is operatively configured to generally provide a thermally conductive heat path between the PCB 2062 and the outer device case / heat spreader 2086. As represented by the arrows, the metamaterial TIM 2085 is also operatively configured to direct or guide signals (e.g., millimeter-wave signals, etc.) from the antenna elements 2088 toward a reflector 2089. The reflector 2089 can then reflect the signal upward, thereby avoiding the problem of the effects of a high dielectric constant on antenna performance.

[0127] Metamaterial patterning (e.g., FSS) can be used on device cases or housings to direct signals to reduce EMI and eliminate or reduce side lobes. As an example, metamaterial FSS can be used within radomes, which can reduce the thickness of the radome, for example, from about 3 millimeters to 1 / 2 millimeter.

[0128] 21A and 21B illustrate an exemplary flexible material 2100 including a filled dielectric pyramid structure that may be fabricated by the process illustrated in FIGS. 2A-2E according to an exemplary embodiment embodying one or more aspects of the present disclosure. The filled dielectric may include carbon black-filled polydimethylsiloxane (PDMS), a filled block copolymer system, a filled elastomer system, a filled thermoplastic system, etc. The pyramid structure may include a rectangular pyramid configured to be operable to mitigate EMI as disclosed herein.

[0129] 21B, the material 2100 having filled dielectric pyramid structures can be flexible and conformal enough to be wrapped around components, devices, etc. Thus, the flexible material 2100 can include a functional (e.g., EMI mitigation, etc.) wrap, which can be wrapped around at least a portion of a PCB (e.g., wrapped on both sides, etc.).

[0130] Traditional board-level shielding works to contain EMI energy by creating a conductive metal Faraday cage around device components. The metal shield also serves to contain thermal energy beneath it. This thermal energy must be released to operate for EMI reduction and heat transfer purposes. Traditional board-level shielding has a rectangular structure of conductive metal with five sides. The sixth side of the Faraday shield is provided by the PCB's ground plane.

[0131] In exemplary embodiments disclosed herein, one or more metal sidewalls of the BLS are replaced by an absorbing material. By way of example, the absorbing material may include one or more multilayer film structures and / or patterned materials disclosed herein, such as multilayer film structures including block copolymer films with domains (e.g., as shown in Figures 3 and 4), FSS structures including FSS elements (e.g., as shown in Figures 6 and 19), and materials with pyramidal and / or non-pyramidal structures (e.g., as shown in Figures 1, 2, 5-15, and 21).

[0132] By controlling the thickness and placement of the absorber, a high impedance wall can be created that blocks or prevents electromagnetic energy from passing through the absorber, which is often frequency specific. The absorbing material can include thermally conductive absorbing materials to facilitate heat transfer in hybrid EMI / thermal devices.

[0133] In an exemplary embodiment, the sidewalls of one or more BLSs can be made of an absorbing material configured to direct or guide different frequencies in different directions so that some frequencies can be attenuated while other frequencies are not attenuated.

[0134] 22 illustrates a board level shield (BLS) 2254 according to an exemplary embodiment 2200 embodying one or more aspects of the present disclosure. The BLS 2254 includes a top 2256 and four side walls. The BLS top 2256 and three side walls 2258 are made of a conductive metal (e.g., sheet metal, etc.). The fourth side wall 2259 is made of an absorbing material 2290 instead of the conductive metal used for the BLS top 2256 and the other three side walls 2258.

[0135] The fourth sidewall 2259 may be made from a thermally conductive, absorbing material 2290 such that the fourth sidewall is thermally conductive. In that case, the fourth sidewall 2259 may be operable to absorb EMI while also allowing for thermal heat transfer. The sidewalls 2258 and 2259 may be configured (e.g., including mounting feet, etc.) for attachment (e.g., soldering, etc.) to the PCT 2262 or other substrate.

[0136] Figure 23 is a line graph showing the simulated reduction in total radiated power in decibels (dB) versus frequency in gigahertz (GHz) for the board-level shield of Figure 22, where the absorber location is different for the two cases, accompanied by a shift in the frequency of maximum total radiated power reduction.

[0137] Exemplary embodiments may include laser cured dopant catalysts (e.g., specks, etc.) in the film to crystallize the dopant and thereby provide enhanced performance, such as thermal management, electromagnetic interference (EMI) mitigation, electrical conductivity, thermal conduction, EMI absorption, magnetism, dielectric properties, and / or structural performance, etc. Other exemplary embodiments may include tape casting with inkjet printed materials into openings (e.g., perforations, notches, holes, etc.) in the film to provide electrical interconnections and / or thermal paths.

[0138] Exemplary embodiments may include methods using at least one of features (e.g., sheets, other extensions or protrusions, etc.), one or more domains in a multilayer block copolymer film structure, doping, and / or patterning to provide EMI mitigation (e.g., EMI shielding, EMI absorption, etc.) and / or thermal management. The features may include pyramidal structures (e.g., rectangular pyramids, etc.) and / or non-pyramidal structures.

[0139] In an exemplary embodiment, a method for fabricating a multilayer thermal management and / or electromagnetic interference (EMI) mitigation material may include creating a block copolymer film having domains by adding one or more fillers or additives to modify one or more properties, characteristics, functions, and / or performance of the domains, such as thermal management, electromagnetic interference (EMI) mitigation, electrical conductivity, thermal conductivity, EMI absorption, magnetic properties, dielectric properties, and / or structural performance.

[0140] In an exemplary embodiment, a method of fabricating a film can include determining a pattern of functionality, selecting a first polymer having a first property, selecting a second polymer having a second property, selecting a functional material (e.g., of a predefined, predetermined shape, etc.) having a third property (e.g., thermal conductivity, electrical conductivity, EMI absorption, dielectric, structural, etc.), and fabricating a film using the first and second polymers and the functional material via a block copolymer process such that when the film is assembled together (e.g., stacked, laminated into a multilayer structure, etc.), it has the pattern of functionality. The pattern of functionality can include column height, column width, column spacing, filler packing, and / or filler density within the columns, etc.

[0141] In an exemplary embodiment, the multi-layer structure includes a base layer including (e.g., molded together, etc.) structures (e.g., pyramidal structures, non-pyramidal structures, etc.) protruding therefrom along at least a first side of the base layer, and a planarizing layer along the first side that provides a substantially planar surface opposite a second side of the base layer.

[0142] The planarization layer may include a dielectric material (e.g., a graded dielectric for impedance matching, a uniform dielectric planarization layer, etc.), a thermally conductive material, an electrically conductive material, etc. At least one film layer may be disposed along (e.g., adhered, etc.) the planarization layer opposite the base layer.

[0143] The multilayer structure may include a frequency selective surface (FSS) element (e.g., a conductive ring, etc.) generally disposed between a film layer and a planarization layer. For example, the FSS element may include a conductive ring in a pattern. The multilayer structure may include multiple FSS layers or films (e.g., a stacked arrangement, etc.) that include FSS elements, e.g., conductive rings printed along or embedded within the multiple layers or films. The FSS element of one layer may overlap the FSS element of another layer. The FSS element may include a base layer that includes an EMI-absorbing material.

[0144] In exemplary embodiments, regions of enhanced or reduced magnetic properties can be created within multilayer film structures and / or patterned materials. For example, regions of magnetic attraction and repulsion can be used when loaded copolymer resins are polymerized into films during extrusion or calendaring.

[0145] In exemplary embodiments where the thermal interface material may be applied and / or used in conjunction with a multilayer film structure and / or patterned material, a wide variety of thermal interface materials may be used, including thermal gap fillers, thermal phase change materials, thermally conductive EMI absorbers or hybrid thermal / EMI absorbers, thermal grease, thermal paste, thermal putty, dispensable thermal interface materials, thermal pads, and the like.

[0146] In exemplary embodiments including or involving board-level shielding, a wide range of materials can be used for the board-level shield (broadly speaking, the shield) or portions thereof, such as cold-rolled steel, nickel-silver alloy, copper-nickel alloy, stainless steel, tin-plated cold-rolled steel, tin-plated copper alloy, carbon steel, brass, copper, aluminum, copper-beryllium alloy, phosphor bronze, steel, alloys thereof, plastic materials coated with conductive materials, or other suitable conductive and / or magnetic materials. The materials disclosed herein are provided herein for illustrative purposes only, as different materials may be used depending on, for example, the particular application.

[0147] Exemplary embodiments may include multilayer film structures and / or patterned materials that include at least portions (e.g., through-thickness domains of a block copolymer film) having a high thermal conductivity (e.g., in the range of about 1 W / mK (watt per meter per Kelvin) to about 6 W / mK), depending on the particular materials used to fabricate the multilayer film and / or patterned material and the loading of thermally conductive fillers, if any. These thermal conductivities are merely examples, as other embodiments may include multilayer films and / or patterned materials that include at least one portion having a thermal conductivity greater than 6 W / mK, less than 1 W / mK, or between 1 and 6 W / mK.

[0148] In exemplary embodiments, at least a portion of the multilayer film structure and / or patterned material may be thermally conductive (e.g., thermally conductive domains of a block copolymer film, etc.) having a relatively high thermal conductivity. In such embodiments, the thermally conductive portions of the multilayer film structure and / or patterned material may be used to define or provide a portion of a thermally conductive thermal path from a heat source to a heat removal / dissipation structure or component. The thermally conductive portions of the multilayer film structure and / or patterned material may be used, for example, to help conduct thermal energy (e.g., heat) from a heat source in an electronic device. The thermally conductive portions of the multilayer film structure and / or patterned material may generally be positioned to establish a thermal bond, interface, pathway, or thermally conductive thermal path between the heat source and the heat removal / dissipation structure or component, along which heat may be transferred (e.g., conducted) from the heat source to the heat removal / dissipation structure or component. In operation, the thermally conductive portions of the multilayer film structure and / or patterned material may function to enable the transfer of heat (e.g., conduct heat, etc.) from a heat source along a thermal conduction path to a heat removal / dissipation structure or component. In exemplary embodiments in which the multilayer film structure and / or patterned material includes at least a portion for EMI mitigation (e.g., conductive and / or EMI absorbing domains of a block copolymer film, etc.), the multilayer film structure and / or patterned material may also be operable to mitigate (e.g., absorb, block, reflect, etc.) EMI incident on the EMI mitigation portions of the multilayer film structure and / or patterned material.

[0149] Exemplary embodiments disclosed herein may be used with a wide range of heat sources, electronic devices (e.g., smartphones, etc.), and / or heat removal / dissipation structures or components (e.g., heat spreaders, heat sinks, heat pipes, vapor chambers, external cases or housings of devices, etc.). For example, a heat source may include one or more heat-generating components or devices (e.g., CPUs, dies 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 portions of the multilayer film structure and / or patterned material or that otherwise provides or transfers heat to the thermally conductive portions of the multilayer film structure and / or patterned material, regardless of whether the heat is generated by or merely transferred through the heat source. Thus, aspects of the present disclosure should not be limited to use with a single type of heat source, electronic device, heat removal / dissipation structure, etc.

[0150] In an exemplary embodiment, the EMI absorbing structure or EMI absorber may be on or along the exterior of the cavity or chamber. The EMI absorber or structure may be configured (e.g., shaped as a cone or pyramid, etc.) to suppress or reduce the probability of reflection of incident radiation (e.g., high frequency radiation at wide angles, radiation at stray frequencies, etc.) through an aperture (e.g., a radar aperture in an automobile) into the cavity or chamber. Thus, placement of the EMI absorber can enable improved performance of electronics (e.g., ADVICS (Advanced Intelligent Chassis Systems), etc.) within the cavity or chamber, filtering out stray frequencies.

[0151] 24 illustrates an example device component 2400 and structures 2404 (e.g., EMI absorbing pyramidal structures, etc.) along the exterior of the device component 2400, according to an example embodiment embodying one or more aspects of the present disclosure. The structures 2404 are configured for EMI mitigation (e.g., absorbing high frequency EMI, etc.).

[0152] The structures 2404 may be disposed (e.g., adhered, etc.) along and protrude outwardly from one or more exterior portions of the device component 2400. In this illustrated embodiment, the structures 2404 are disposed along the exterior or outer surface of the top wall or portion 2408 of the device. The structures 2404 are also disposed along the exterior or outer surface of the side or side walls 2412 of the device.

[0153] The device component 2400 can define an interior, cavity, or chamber 2416 and an opening 2420 to the chamber 2416 (e.g., an automotive radar aperture, a non-automotive radar aperture, other radar aperture, etc.). In the illustrated embodiment, a structure 2404 is disposed along and / or defines the entire top surface 2408 of the device component 2400, which in turn defines the opening 2420 to the chamber 2416. Thus, the structure 2404 is disposed around the entire periphery of the opening 2420. In an alternative embodiment, an EMI absorbing structure can be disposed along one or more interior surfaces of the device component within the chamber 2416. In such an alternative embodiment, the EMI absorbing structure 2404 (e.g., a pyramidal structure, etc.) may be disposed along both the interior and exterior surfaces of the device component 2400 such that the EMI absorbing structure protrudes inward and outward in opposite directions relative to the device component 2400.

[0154] Device component 2400 may include an electronics housing, a board-level shield (BLS), other device components, etc. Device component 2400 may be configured (e.g., formed of metal, shaped, sized, etc.) to mitigate (e.g., block, reflect, etc.) low-frequency EMI. Structure 2404 may be configured (e.g., formed of EMI-absorbing material, shaped, sized, etc.) to mitigate (e.g., absorb, etc.) high-frequency EMI.

[0155] The placement of the structure 2404 along the exterior of the device component 2400 may reduce the likelihood of incident radiation reflecting through the opening 2420 into the interior, chamber, or cavity 2416. The structure 2404 may be operable to reduce or prevent incident radiation from reflecting through the opening 2420 into the cavity or chamber 2416.

[0156] By way of example, the structure 2404 may be configured to be operable to suppress high frequency radiation at wide angles into the opening 2420. The placement of the EMI absorbing structure 2404 can enable improved performance of electronic equipment (e.g., ADVICS (Advanced Intelligent Chassis Systems) etc.) within the cavity or chamber 2416, filtering out stray frequencies.

[0157] The EMI absorbing structure 2404 may include a rectangular pyramid (such as, for example, the rectangular pyramid 2504 shown in FIG. 25). The rectangular bases of adjacent pyramids may substantially touch each other without any gaps or spacing between the rectangular bases. This helps avoid reflectivity that may occur if there were gaps between the rectangular bases of the pyramidal structures. Other exemplary embodiments may include non-pyramid structures that taper or decrease in width (e.g., generally smoothly curved, etc.) from the top (e.g., apex) to the base. Alternative exemplary embodiments may include structures having non-rectangular bases, such as hexagonal bases, triangular bases, etc. Thus, the present disclosure should not be limited solely to rectangular pyramid structures, as other exemplary embodiments may include structures having different three-dimensional geometric shapes.

[0158] In exemplary embodiments, the sides of structure 2404 may not be perfectly smooth or define a perfectly straight line from top to bottom. For example, when viewed under high magnification, the sides may appear to have a stepped configuration. However, the sides of a pyramidal or non-pyramidal structure are preferably relatively smooth (e.g., free of significant steps) to reduce or avoid reflections of EMI incident on the structure. Additionally, the structure may be configured to have varying slopes or tapers along its sides (e.g., at least two or more slopes). For example, a pyramidal structure may have a relatively gradual taper from the base to a central portion, a more rapid taper from the central portion to the top, and a smaller taper from there to the top of the structure.

[0159] Structures 2404, 2504 may include a filled dielectric, such as carbon black filled polydimethylsiloxane (PDMS), another filled block copolymer system, a filled elastomer system, a filled thermoplastic system, a carbon nanotube filled injection moldable resin, a carbon nanotube filled polymer resin, etc. Alternatively, structures 2404, 2504 may be made of other materials and / or by other suitable processes (e.g., stepwise deposition of material onto a functional carrier film, etc.).

[0160] In exemplary embodiments, the configurations (e.g., heights, shapes, positions, etc.) of structures 2404 may be non-randomized or randomized (e.g., via a computerized randomization process, etc.). Randomizing the heights of structures 2404 along the outside of device component 2400 may help reduce or avoid cavity resonances beneath the device housing in which device component 2400 is housed. An exemplary embodiment may include rectangular pyramidal structures with bases of the same size, but one or more rectangular pyramidal structures may have a different height than one or more other rectangular pyramidal structures.

[0161] Using structures with different heights can accommodate variations in the heights of shorter and taller adjacent components. For example, the taller and shorter structures can be positioned relative to the device component 2400 such that the taller and shorter structures 2404 align with the shorter and taller components, respectively, when the device component 2400 is installed in an electronic device. The different heights of the structures can also help avoid or reduce cavity resonances within the device housing in which the device component 2400 is housed.

[0162] The pyramidal structures may include air-filled particles (e.g., air-filled microballoons, air-filled microbubbles, air-filled microspheres, etc.) to controllably reduce the dielectric constant of the pyramidal structures. The air-filled particles add air to the pyramidal structures, which reduces the dielectric constant (e.g., approximates and / or resembles foam).

[0163] FIG. 25 illustrates a pyramidal structure 2504 of an EMI absorber (e.g., EMI absorber 2404, etc.) according to an exemplary embodiment embodying one or more aspects of the present disclosure. By way of example only, the pyramidal structure 204 may have the following parameters: a flat base thickness of approximately 2.5 millimeters (mm), a wedge thickness of approximately 2 mm, a wedge or pyramid height of approximately 3 mm, a truncated pyramid tip of approximately 0.5 mm, a height value of 0.5 mm, and a dielectric constant of 11-3.3. In this example, the pyramid height is 3 mm, but the base of the pyramid 2504 is inside the flat base by a distance below the apex of the "valley height" which is 0.5 mm. This was done to control the "valley" during modeling. A "valley height" value of 0 causes the pyramid base to be flush with the apex of the flat base. The pyramid tip is truncated by a value equal to "truncate" (0.5 mm). At a "truncate" value of 0, the pyramid reaches the "wedge height" value (3 mm). When "truncate" and "valley height" are zero, better electromagnetic performance is obtained, resulting in sharp pyramids and sharp valleys, but non-zero values ​​for "truncate" and "valley height" may be based on manufacturing capabilities.

[0164] In an exemplary embodiment, a composition for an electromagnetic interference (EMI) absorber includes generally cylindrical carbon nanotubes having varying inner diameters and / or varying outer diameters. In an exemplary embodiment, the carbon nanotubes include hollow, generally cylindrical, tubular multi-walled carbon nanotubes, at least one multi-walled carbon nanotube having an inner diameter and an outer diameter that are different, respectively, from the inner diameter and outer diameter of at least one other multi-walled carbon nanotube.

[0165] In an exemplary embodiment, the carbon nanotubes include multi-walled carbon nanotubes, at least one of the multi-walled carbon nanotubes having a different number of walls than at least one other of the multi-walled carbon nanotubes.

[0166] In an exemplary embodiment, the carbon nanotubes are generally cylindrical and have a variable inner diameter and a variable outer diameter. In exemplary embodiments, the carbon nanotubes include multi-walled carbon nanotubes. The carbon nanotubes may further include carbon nanostructures including branched networks of single-walled carbon nanotubes and / or bridged carbon nanotube structures.

[0167] In an exemplary embodiment, the carbon nanotubes are present in an injection moldable resin. The composition may further include carbon black in the injection moldable resin. In an exemplary embodiment, the carbon nanotubes are present in a resin comprising one or more of liquid silicone, urethane, polycarbonate, polyamide, polyester, polyolefin, polybutylene terephthalate, polypropylene, thermoplastic vulcanizate, thermoplastic elastomer, nylon, and / or a blend comprising polyolefin.

[0168] In an exemplary embodiment, the carbon nanotubes are present in a resin comprising polypropylene and Santoprene® thermoplastic vulcanizate. For example, the composition may comprise about 10 volume percent or less of Santoprene® thermoplastic vulcanizate, about 89 volume percent or more of polypropylene, and about 0.3 volume percent or less of carbon nanotubes.

[0169] In an exemplary embodiment, the composition comprises no more than about 2 weight percent carbon nanotubes. In an exemplary embodiment, the composition further comprises one or more fillers and / or additives, wherein the one or more fillers and / or additives comprise one or more pigments, plasticizers, processing aids, flame retardants, extenders, tackifiers, EMI absorbers, conductive fillers, and / or magnetic particles.

[0170] In an exemplary embodiment, an automotive vehicle part is injection molded from the compositions disclosed herein to have a monolithic, single-piece construction. In an exemplary embodiment, a thermal management and EMI mitigation material comprises a composition disclosed herein and is configured to be multifunctional, with a first function of EMI mitigation and a second function of thermal management.

[0171] In an exemplary embodiment, the electromagnetic interference (EMI) absorber includes one or more EMI absorbing structures, the one or more EMI absorbing structures including generally cylindrical carbon nanotubes having varying inner diameters and / or varying outer diameters.

[0172] In an exemplary embodiment of the EMI absorber, the carbon nanotubes comprise hollow, generally cylindrical, tubular multi-walled carbon nanotubes, at least one multi-walled carbon nanotube having an inner diameter and an outer diameter that are different, respectively, from the inner diameter and outer diameter of at least one other multi-walled carbon nanotube.

[0173] In an exemplary embodiment of the EMI absorber, the carbon nanotubes include multi-walled carbon nanotubes, at least one multi-walled carbon nanotube having a different number of walls than at least one other multi-walled carbon nanotube.

[0174] In an exemplary embodiment of the EMI absorber, the carbon nanotubes are generally cylindrical and have a variable inner diameter and a variable outer diameter. In an exemplary embodiment of the EMI absorber, the carbon nanotubes comprise multi-walled carbon nanotubes, which may further comprise carbon nanostructures comprising branched networks of single-walled carbon nanotubes and / or cross-linked carbon nanotube structures.

[0175] In exemplary embodiments of the EMI absorber, the one or more EMI absorbing structures comprise about 2 weight percent or less of carbon nanotubes, the EMI absorber is configured to operate at frequencies between about 40 gigahertz (GHz) and about 120 GHz, and / or between about 60 GHz and about 90 GHz, and / or between about 70 GHz and about 85 GHz with a return loss of greater than 15 decibels, and / or the EMI absorber is configured to operate at a frequency of about 77 GHz with a return loss of greater than 15 decibels.

[0176] In exemplary embodiments of the EMI absorber, the carbon nanotubes are present in a resin comprising one or more of liquid silicone, urethane, polycarbonate, polyamide, polyester, polyolefin, polybutylene terephthalate, polypropylene, thermoplastic vulcanizate, thermoplastic elastomer, nylon, and / or blends comprising polyolefin.

[0177] In an exemplary embodiment of the EMI absorber, the carbon nanotubes are present in a resin comprising polypropylene and Santoprene® thermoplastic vulcanizate. For example, the composition may comprise about 10 volume percent or less of Santoprene® thermoplastic vulcanizate, about 89 volume percent or more of polypropylene, and about 0.3 volume percent or less of carbon nanotubes.

[0178] In an exemplary embodiment of the EMI absorber, the one or more EMI absorbing structures include a pattern of rectangular pyramidal structures including rectangular bases configured such that the rectangular bases of adjacent rectangular pyramidal structures contact one another with substantially no gap or spacing between the rectangular bases of adjacent rectangular pyramidal structures.

[0179] In an exemplary embodiment of the EMI absorber, a low dielectric loss, low permittivity material is disposed over one or more EMI absorbing structures, the low dielectric loss, low permittivity material defining a planarizing layer having an inverted pattern that is disposed to interlock with the one or more EMI absorbing structures, such that the one or more EMI absorbing structures and the planarizing layer have an overall generally planar configuration and / or the planarizing layer defines a planar surface over the one or more EMI absorbing structures.

[0180] 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.

[0181] 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.

[0182] 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.

[0183] 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.

[0184] 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," when used herein when modifying 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 equivalent amounts are included regardless of whether they are modified by the term "about."

[0185] 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.

[0186] 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.

[0187] 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. A composition for use as an electromagnetic interference (EMI) absorber, the composition comprising a plurality of generally cylindrical carbon nanotubes having varying inner diameters and / or varying outer diameters.

2. 10. The composition of claim 1, wherein the plurality of carbon nanotubes comprises a plurality of hollow, generally cylindrical, tubular multi-walled carbon nanotubes, at least one of the plurality of multi-walled carbon nanotubes having an inner diameter and an outer diameter that are different, respectively, from the inner diameter and outer diameter of at least one other of the plurality of multi-walled carbon nanotubes.

3. 10. The composition of claim 1, wherein the plurality of carbon nanotubes comprises a plurality of multi-walled carbon nanotubes, at least one of the plurality of multi-walled carbon nanotubes having a different number of walls than at least one other of the plurality of multi-walled carbon nanotubes.

4. 10. The composition of claim 1, wherein the plurality of carbon nanotubes are generally cylindrical and have a variable inner diameter and a variable outer diameter.

5. The composition of claim 1 , wherein the plurality of carbon nanotubes comprises a plurality of multi-walled carbon nanotubes.

6. The composition of claim 5 , wherein the plurality of carbon nanotubes further comprises a carbon nanostructure comprising a branched network of single-walled carbon nanotubes and / or bridged carbon nanotube structures.

7. The composition of any one of claims 1 to 6, wherein the plurality of carbon nanotubes are present in an injection moldable resin.

8. The composition of claim 7 further comprising carbon black within the injection moldable resin.

9. 7. The composition of claim 1, wherein the plurality of carbon nanotubes are present in a resin comprising one or more of liquid silicone, urethane, polycarbonate, polyamide, polyester, polyolefin, polybutylene terephthalate, polypropylene, thermoplastic vulcanizate, thermoplastic elastomer, nylon, and / or a blend comprising a polyolefin.

10. The composition of any one of claims 1 to 6, wherein the plurality of carbon nanotubes are present in a resin comprising polypropylene and Santoprene® thermoplastic vulcanizate.

11. 11. The composition of claim 10, comprising about 10 volume percent or less of the Santoprene® thermoplastic vulcanizate, about 89 volume percent or more of polypropylene, and about 0.3 volume percent or less of carbon nanotubes.

12. The composition of any one of claims 1 to 6, comprising up to about 2 weight percent carbon nanotubes.

13. 7. The composition of any one of claims 1 to 6, wherein the composition further comprises one or more fillers and / or additives, the one or more fillers and / or additives comprising one or more pigments, plasticizers, processing aids, flame retardants, extenders, tackifiers, EMI absorbers, conductive fillers, and / or magnetic particles.

14. 7. An EMI absorber comprising the composition of any one of claims 1 to 6, wherein the EMI absorber comprises one or more EMI absorbing structures.

15. 15. The EMI absorber of claim 14, wherein the one or more EMI absorbing structures include a pattern of rectangular pyramidal structures including rectangular bases configured such that the rectangular bases of adjacent rectangular pyramidal structures contact each other with substantially no gap or spacing between the rectangular bases of adjacent rectangular pyramidal structures.

16. 15. The EMI absorber of claim 14, further comprising a low dielectric loss, low permittivity material disposed over the one or more EMI absorbing structures, the low dielectric loss, low permittivity material defining a planarization layer having an inverted pattern disposed to mate with the one or more EMI absorbing structures, such that the one or more EMI absorbing structures and the planarization layer have an overall generally planar configuration and / or the planarization layer defines a planar surface over the one or more EMI absorbing structures.

17. the EMI absorber is configured to operate at frequencies between about 40 gigahertz (GHz) and about 120 GHz, and / or between about 60 GHz and about 90 GHz, and / or between about 70 GHz and about 85 GHz with a return loss of greater than 15 decibels; and / or 15. The EMI absorber of claim 14, wherein the EMI absorber is configured to operate at a frequency of about 77 GHz with a return loss of greater than 15 decibels.

18. An automotive vehicle part injection molded from the composition of any one of claims 1 to 6 to have a monolithic, single-piece construction.

19. A thermal management and EMI mitigation material configured to be multifunctional, having a first function of EMI mitigation and a second function of thermal management, comprising the composition of any one of claims 1 to 6.

20. 1. An EMI absorber comprising one or more electromagnetic interference (EMI) absorbing structures, the one or more EMI absorbing structures comprising a plurality of generally cylindrical carbon nanotubes having varying inner diameters and / or varying outer diameters.

21. 21. The EMI absorber of claim 20, wherein the plurality of carbon nanotubes comprises a plurality of hollow, generally cylindrical, tubular multi-walled carbon nanotubes, at least one of the plurality of multi-walled carbon nanotubes having an inner diameter and an outer diameter that are different, respectively, from the inner diameter and outer diameter of at least one other of the plurality of multi-walled carbon nanotubes.

22. 21. The EMI absorber of claim 20, wherein the plurality of carbon nanotubes comprises a plurality of multi-walled carbon nanotubes, at least one of the plurality of multi-walled carbon nanotubes having a different number of walls than at least one other of the plurality of multi-walled carbon nanotubes.

23. 21. The EMI absorber of claim 20, wherein the plurality of carbon nanotubes are generally cylindrical and have a varying inner diameter and a varying outer diameter.

24. 21. The EMI absorber of claim 20, wherein the plurality of carbon nanotubes comprises a plurality of multi-walled carbon nanotubes.

25. 25. The EMI absorber of claim 24, wherein the plurality of carbon nanotubes further comprises carbon nanostructures including a branched network of single-walled carbon nanotubes and / or bridged carbon nanotube structures.

26. the one or more EMI absorbing structures comprise about 2 weight percent or less of carbon nanotubes; the EMI absorber is configured to operate at frequencies between about 40 gigahertz (GHz) and about 120 GHz, and / or between about 60 GHz and about 90 GHz, and / or between about 70 GHz and about 85 GHz with a return loss of greater than 15 decibels; and / or 26. The EMI absorber of any one of claims 20 to 25, wherein the EMI absorber is configured to operate with a return loss of greater than 15 decibels at a frequency of about 77 GHz.

27. 26. The EMI absorber of any one of claims 20 to 25, wherein the plurality of carbon nanotubes are present in a resin comprising one or more of liquid silicone, urethane, polycarbonate, polyamide, polyester, polyolefin, polybutylene terephthalate, polypropylene, thermoplastic vulcanizate, thermoplastic elastomer, nylon, and / or blends comprising polyolefin.

28. 26. The EMI absorber of any one of claims 20 to 25, wherein the plurality of carbon nanotubes are present in a resin comprising polypropylene and Santoprene® thermoplastic vulcanizate.

29. 30. The EMI absorber of claim 28 comprising about 10 volume percent or less of the Santoprene® thermoplastic vulcanizate, about 89 volume percent or more of polypropylene, and about 0.3 volume percent or less of carbon nanotubes.

30. 26. The EMI absorber of any one of claims 20 to 25, wherein the one or more EMI absorbing structures comprise a pattern of rectangular pyramidal structures including rectangular bases configured such that the rectangular bases of adjacent rectangular pyramidal structures contact each other with substantially no gap or spacing between the rectangular bases of adjacent rectangular pyramidal structures.

31. 26. The EMI absorber of claim 20, further comprising a low dielectric loss, low permittivity material disposed on the one or more EMI absorbing structures, the low dielectric loss, low permittivity material defining a planarization layer having an inverted pattern disposed to mate with the one or more EMI absorbing structures, such that the one or more EMI absorbing structures and the planarization layer have an overall generally planar configuration, and / or the planarization layer defines a planar surface over the one or more EMI absorbing structures.

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