WO2020123500A1

WO2020123500A1 - Electromagnetic interference (emi) absorbers and methods of mitigating emi

Info

Publication number: WO2020123500A1
Application number: PCT/US2019/065470
Authority: WO
Inventors: Pawel WEGRZYNIAK; Paul Francis DIXON; Douglas S. Mcbain
Original assignee: Laird Technologies Inc
Current assignee: Laird Technologies Inc
Priority date: 2018-12-10
Filing date: 2019-12-10
Publication date: 2020-06-18
Anticipated expiration: 2021-06-10

Abstract

Disclosed are exemplary embodiments of electromagnetic interference (EMI) absorbers. Also disclosed are exemplary methods of mitigating EMI. In exemplary embodiments, EMI absorbing structures or EMI absorbers may be exterior to or along the outside of a cavity or chamber. The EMI absorbers or structures may be configured to suppress or reduce the probability of reflection of incident radiation through an aperture into the cavity or chamber.

Description

ELECTROMAGNETIC INTERFERENCE (EMI) ABSORBERS AND

METHODS OF MITIGATING EMI

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/777,515 filed December 10, 2018. The entire disclosure of the above application is incorporated herein by reference.

FIELD

[0002] The present disclosure relates to electromagnetic interference (EMI) absorbers and methods of mitigating EMI.

BACKGROUND

[0003] This section provides background information related to the present disclosure which is not necessarily prior art.

[0004] Electrical components, such as semiconductors, integrated circuit packages, transistors, etc., typically have pre-designed temperatures at which the electrical components optimally operate. Ideally, the pre-designed temperatures approximate the temperature of the surrounding air. But the operation of electrical components generates heat. If the heat is not removed, the electrical components may then operate at temperatures significantly higher than their normal or desirable operating temperature. Such excessive temperatures may adversely affect the operating characteristics of the electrical components and the operation of the associated device.

[0005] To avoid or at least reduce the adverse operating characteristics from the heat generation, the heat should be removed, for example, by conducting the heat from the operating electrical component to a heat sink. The heat sink may then be cooled by conventional convection and/or radiation techniques. During conduction, the heat may pass from the operating electrical component to the heat sink either by direct surface contact between the electrical component and heat sink and/or by contact of the electrical component and heat sink surfaces through an intermediate medium or thermal interface material (TIM). The thermal interface material may be used to fill the gap between thermal transfer surfaces, in order to increase thermal transfer efficiency as compared to having the gap filled with air, which is a relatively poor thermal conductor. [0006] In addition, a common problem in the operation of electronic devices is the generation of electromagnetic radiation within the electronic circuitry of the equipment. Such radiation may result in electromagnetic interference (EMI) or radio frequency interference (RFI), which can interfere with the operation of other electronic devices within a certain proximity. Without adequate shielding, EMI/RFI interference may cause degradation or complete loss of important signals, thereby rendering the electronic equipment inefficient or inoperable.

[0007] A common solution to ameliorate the effects of EMI/RFI is through the use of shields capable of absorbing and/or reflecting and/or redirecting EMI energy. These shields are typically employed to localize EMI/RFI within its source, and to insulate other devices proximal to the EMI/RFI source.

[0008] The term“EMI” as used herein should be considered to generally include and refer to EMI emissions and RFI emissions, and the term“electromagnetic” should be considered to generally include and refer to electromagnetic and radio frequency from external sources and internal sources. Accordingly, the term shielding (as used herein) broadly includes and refers to mitigating (or limiting) EMI and/or RFI, such as by absorbing, reflecting, blocking, and/or redirecting the energy or some combination thereof so that it no longer interferes, for example, for government compliance and/or for internal functionality of the electronic component system.

DRAWINGS

[0009] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and is not intended to limit the scope of the present disclosure.

[0010] FIG. 1 illustrates EMI absorbing pyramidal structures along the outside of a device component that defines a cavity or chamber according to an exemplary embodiment.

[0011] FIG. 2 illustrates a pyramidal structure for an EMI absorber according to exemplary embodiment.

[0012] Corresponding reference numerals may indicate corresponding (but not necessarily identical) parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0013] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0014] Disclosed herein are exemplary embodiments of electromagnetic interference (EMI) absorbers. Also disclosed are exemplary methods of mitigating EMI. In exemplary embodiments, EMI absorbing structures or EMI absorbers may be exterior to or along the outside of a cavity or chamber. The EMI absorbers or structures may be configured ( e.g ., shaped with cones or pyramids, 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., an automotive radar aperture, etc.) into the cavity or chamber. The EMI absorber placement may thus allow for improved performance of electronics (e.g., ADVICS (ADVanced Intelligent Chassis Systems), etc.) inside the cavity or chamber and remove stray frequencies.

[0015] With reference to the figures, FIG. 1 illustrates an exemplary device component 100 and structures 104 (e.g., EMI absorbing pyramidal structures, etc.) along the outside of the device component 100 according to an exemplary embodiment embodying one or more aspects of the present disclosure. The structures 104 are configured for EMI mitigation (e.g., absorbing high frequency EMI, etc.).

[0016] The structures 104 may be disposed along (e.g., adhered to, etc.) and protrude outwardly from one or more exterior portions of the device component 100. In this illustrated embodiment, structures 104 are disposed along an exterior or outer surface of the device’s top wall or portion 108. Structures 104 are also disposed along the exterior or outer surface of the device’s sides or sidewalls 112.

[0017] The device component 100 may be define an interior, cavity, or chamber 116 and an aperture or opening 120 (e.g., automotive radar aperture, etc.) into the chamber 116. In this illustrated embodiment, the structures 104 are disposed along and/or define the entire top surface 108 of the device component 100, which, in turn, defines the aperture 120 into the chamber 116. Accordingly, the structures 104 are disposed around the entire perimeter of the aperture 120. In alternative embodiments, EMI absorbing structures may also be disposed along one or more inner surfaces of the device component within the chamber 116. In such alternative embodiments, EMI absorbing structures 104 (e.g., pyramidal structures, etc.) may be disposed along both the inner and outer surfaces of the device component 100, such that EMI absorbing structures protrude inwardly and outwardly in opposite directions relative to the device component 100.

[0018] The device component 100 may comprise an electronics housing, a board level shield (BLS), other device component, etc. The device component 100 may be configured (e.g., made of metal, shaped, sized, etc.) for mitigating (e.g., blocking, reflecting, etc.) low frequency EMI. The structures 104 may be configured (e.g., made of EMI absorbing materials, shaped, sized, etc.) for mitigating (e.g., absorbing, etc.) high frequency EMI.

[0019] Placement of the structures 104 along the outside of the device component 100 may reduce the probability that incident radiation will reflect through the aperture 120 into the interior, chamber, or cavity 116. The structures 104 may be operable to suppress or inhibit the reflection of incident radiation through the aperture 120 into the cavity or chamber 116.

[0020] By way of example, the structures 104 may be configured to be operable for suppressing high frequency radiation at wide angles to the aperture 120. The placement of the EMI absorbing structures 104 may allow for improved performance of electronics (e.g., ADVICS (ADVanced Intelligent Chassis Systems), etc.) inside the cavity or chamber 116 and remove radiation at stray frequencies.

[0021] The EMI absorbing structures 104 may comprise rectangular pyramids (e.g., rectangular pyramid 204 shown in FIG. 2, etc.). The rectangular bases of adjacent pyramids may contact each other substantially without any gaps or spaced distances between the rectangular bases. This helps avoiding reflectivity that might otherwise occur if there were gaps between the rectangular bases of the pyramidal structures. Other exemplary embodiments may include non-pyramidal structures that taper or decrease (e.g., curve generally smoothly, etc.) in width from the top (e.g., from a point, etc.) towards the base. Alternative exemplary embodiments may include structures having non-rectangular bases, e.g., hexagonal bases, triangular bases, etc. Accordingly, the present disclosure should not be limited to only rectangular pyramidal structures as other exemplary embodiments may include structures having different three-dimensional geometric shapes.

[0022] In exemplary embodiments, the sides of the structures 104 may not be perfectly smooth or define a perfectly straight line from top to bottom. For example, the sides may appear to have a stepped configuration when viewed at high magnification. But the sides of the pyramidal or non- pyramidal structures may preferably be relatively smooth (e.g., without any significantly sized steps, etc.) to reduce or avoid reflection of EMI incident on the structures. In addition, the structures may be configured to have a varying slope or taper (e.g., at least two or more slopes, etc.) along the sides. For example, a pyramidal structure may have a relatively gradual taper from the base towards a middle portion, a quicker taper from the middle portion towards the top, and then less taper therefrom to the top of the structure.

[0023] The structures 104, 204 may comprise a filled dielectric, such as polydimethylsiloxne (PDMS) filled with carbon black, another filled block copolymer system, a filled elastomeric system, a filled thermoplastic system, etc. Alternatively, the structures 104, 204 may be made of other materials and/or by other suitable processes (e.g., a stepwise deposition of material onto a functional carrier film, etc.).

[0024] In exemplary embodiments, the configuration (e.g., height, shape, location, etc.) of the structures 104 may be non-randomized or randomized (e.g., via a computerized randomization process, etc.). Randomizing height of the structures 104 along the outside of the device component 100 may help to reduce or avoid cavity resonance underneath the device housing in which the device component 100 is housing. Exemplary embodiments may include rectangular pyramidal structures having the same size base but one or more of the rectangular pyramidal structures may have a different height than one or more other rectangular pyramidal structures.

[0025] Structures having different heights may be used to accommodate for variances in the height of shorter and taller adjacent components. For example, taller and shorter structures may be located relative to the device component 100 so that the taller and shorter structures 104 are aligned with shorter and taller components, respectively, when the device component 100 is installed within an electronic device. The different heights of the structures may help to avoid or reduce cavity resonance within the device housing in which the device component 100 is housed.

[0026] The pyramidal structures may include air- filled particles (e.g., air- filled microballoons, air-filled microbubbles, air- filled microspheres, etc.) for controllably decreasing dielectric constant of the pyramidal structures. The air- filled particles add air to the pyramidal structures, which decreases the dielectric constant (e.g., approximates foam, approaches foam properties, etc.).

[0027] FIG. 2 illustrates a pyramidal structure 204 for an EMI absorber (e.g., EMI absorber 104, etc.) according to 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 e.g., a flat base that is about 2.5 millimeters (mm) thick, a wedge thickness of about 2 mm, a wedge or pyramid height of about 3 mm, a trunc or truncated tip of the pyramid that is about 0.5 mm, a value height of 0.5 mm, and permittivity of 11 - j 3.3. In this example, the pyramid height is 3 mm, but the base of the pyramid 204 is inside the flat base at a distance below the top of valleyheight which is 0.5mm. This was done for controlling the“valley” during modelling. A value of 0 for the valleyheight would make the pyramid base at the same position of the flat base top. The tip of the pyramid is truncated by a value equal to trunc (0.5 mm). For a 0 value for trunc, the pyramid would come to a point at the wedgeheight value (3 mm). Although better electromagnetic performance may be obtained if trunc and valleyheight are zero making sharp pyramids and sharp valleys, non-zero values for the trunc and valleyheight may be based on manufacturing capabilities.

[0028] Exemplary embodiments may include one or more EMI absorbing structures comprising films ( e.g ., multilayer block copolymer films, homogeneous block copolymer films, single layer block copolymer films etc.) and/or patterned materials (e.g., roll to roll pattemable polymer, etc.), which may have controlled and/or tailored performance (e.g., thermal management, electromagnetic interference (EMI) mitigation, electrical conductivity, thermal conductivity, EMI absorbing, magnetic, dielectric, and/or structural performance, etc.).

[0029] Exemplary embodiments may include a pattern of EMI absorbing structures (e.g., pattern of pyramidal structures, hierarchical pattern, pattern of non-pyramidal structures, pattern of bell shaped structures, combinations thereof, etc.). The pattern of EMI absorbing structures may comprise filled dielectric, such as polydimethylsiloxane (a) filled with carbon black, a filled block copolymer system, a filled elastomeric system (e.g., cured elastomers, thermoplastic elastomers (TPEs), Santoprene thermoplastic vulcanizate, etc.), a filled thermoplastic system (e.g., polyamide, acrylonitrile butadiene styrene (ABS), polypropylene (PP), polyethylene (PE), etc.), etc. The structural pattern may comprise a pattern of pyramidal structures (e.g., rectangular pyramids, pyramidal frustums with rectangular bases, other pyramidal structures, etc.), non-pyramidal structures, or a combination of pyramidal structures and non-pyramidal structures.

[0030] In exemplary embodiments, various processes may be used to make patterns of EMI absorbing structures (e.g., structures 104 (FIG. 1), etc.) in filled dielectric systems. Example processes include roll to roll processes, such as a roll to roll patternable polymer process for continuous pattern replication, a roll to roll process including multiple nozzles for dispensing materials simultaneously onto a film or layer, etc. Other example processes include extrusion, curtain coating, 3D printing or additive manufacturing (e.g., fused deposition molding, stereolithography, laser direct structuring with molding, etc.), frontal photo polymerization with photomask and/or with soft master, CNC (computer numerical control) milling, injection or compression molding (e.g., using thermoset molds, etc.), soft molding (e.g., using pre-molded (crosslinked) PDMS molds, etc.), UV systems with conveyor belts thermoplastic replication, thermoset master, thiol-ene with a soft master, inkjetting (e.g., inkjetting dielectrics onto metal for insulation, etc.), screenprinting, spraying, laser welding of discrete layers (e.g., at varying depths into different layers, etc.), laser patterning onto polyimide film to allow plating (e.g., plating for FSS elements, etc.), casting, injection molding, rolling/forming processes, integrated parts containing pyramid surfaces in design, etc.

[0031] In an exemplary embodiment, a 3D printed mold insert may be used along with a compression or injection molding process. Pattern fabrication may be performed in a vacuum oven. For example, a 3D printed master may be placed on a metal sheet. A flat composite sheet (e.g., polycaprolactone filled with carbon black, etc.) made by compression molding may then be placed onto the 3D printed master and surrounded by a bracket. Weight (e.g., metal block etc.) may be placed on top of the composite sheet. The pattern is created in the composite sheet from the negative pattern of the 3D printed master using the gravity of the weight atop the composite sheet. The materials are heated in an oven and then removed from the oven. The materials are allowed to cool before the composite is separated from the 3D printed master.

[0032] In an exemplary embodiment, a roll to roll process may be used to make structural patterns in filled dielectric systems. This process may include roll to roll self-aligning self-patterning block copolymer having sufficient particle loading for good or satisfactory performance. A patterned PDMS belt may be used to pattern along with heating plates, which may be a tunnel oven, etc. The patterned PDMS belt may include multiple negatively patterned (e.g., silicone, etc.) parts having their ends bonded or joined together with PDMS. The PDMS may be cured along the joints between the ends of the negatively patterned parts. The patterned PDMS belt is wrapped around rollers. The rollers may be spaced apart by a sufficient distance to avoid sagging of the patterned PDMS belt.

[0033] During the roll to roll process, a carrier (e.g., aluminum carrier with a release layer, etc.) for an uncured mixture of PDMS and carbon black (or other filled dielectric system) is moved across the heating plate. The patterned PDMS belt contacts the uncured mixture of PDMS and carbon black. After a sufficient amount of contact time with the patterned PDMS belt that allows mold filling to be completed, the process may begin for curing the uncured mixture of PDMS and carbon black. The cured PDMS and carbon black part may then be removed from (e.g., peeled off, etc.) the patterned PDMS belt and the carrier. [0034] In an exemplary embodiment, a stepwise deposition process may be used to provide patterns ( e.g ., pyramidal structures 104 shown in FIG. 1, non-pyramidal pattern, combination thereof, etc.). In this exemplary embodiment, the process may include the stepwise deposition of materials (e.g., thermally-conductive, electrically-conductive, EMI absorbing, magnetic, and/or dielectric materials, etc.) onto a functional carrier film. The functional carrier film may comprise a filled dielectric system, such as polydimethylsiloxane (PDMS) filled with carbon black, a filled block copolymer system, a filled elastomeric system (e.g., cured elastomers, thermoplastic elastomers (TPEs), Santoprene thermoplastic vulcanizate, etc.), a filled thermoplastic system (e.g., polyamide, acrylonitrile butadiene styrene (ABS), polypropylene (PP), polyethylene (PE), etc.), etc. The functional carrier film may comprise Kapton polyimide film, Mylar polyester film, a thermoplastic film usable with stereolithography (SLA) printing, etc.

[0035] In exemplary embodiments, materials may be deposited or otherwise applied onto the functional carrier film by spraying, printing, additive manufacturing, etc. For example, materials may be applied to a functional carrier film by laser jet printing a first layer of material (e.g., electrically- conductive and/or thermally-conductive ink, etc.) onto the functional carrier film. A second layer of the same or different material may be laser jet printed on top of the first layer. This may be performed as part of a roll to roll process along which a laser jet printer has been added.

[0036] In exemplary embodiments, a film or layer may be provided (e.g., via additive manufacturing, etc.) with materials thereon have different thicknesses or heights to accommodate for variances in the size of adjacent components. In exemplary embodiments, a bottom film or layer of a multilayer film structure may be configured to allow the multilayer film structure to be removably detachable from and reattachable to a support surface, e.g., via tack, adhesive, mechanical attachment, etc. For example, a multilayer film structure may be attached to, removed from and reattached to a support surface without damaging (e.g., without cutting, without deformation from stretching, etc.) the multilayer film structure.

[0037] The above described processes may be used to provide a wide variety of patterns of different structural shapes (e.g., rectangular pyramids, pyramidal structures, non-pyramidal structures, combinations thereof, etc.), including the exemplary structures 104 and 204 respectively shown in FIGS. 1 and 2. A pattern of structures may also be provided by other suitable processes. For example, a pattern of structures may comprise a multilayer film, a single-layer film, or a homogeneous layer/film with through-thickness domains tailored for a specific performance as disclosed herein. Or, for example, a pattern of structures may comprise metamaterial.

[0038] In exemplary embodiments, a multilayer film (broadly, a multilayer structure) includes multiple block copolymer films or layers having through-thickness domains. By way of example, the block copolymer may comprise polystyrene-polyethylene block copolymer (e.g., polystyrene-block-poly(ethylene oxide) (PS-b-PEO), etc.), polystyrene-acrylate block copolymer (e.g., polystyrene and poly(methyl methacrylate) (PS-PMMA), etc.), 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 copolymer (e.g., segmented polyester- polyether, segmented polyamide-polyether, etc.), polyolefinic block copolymer, ethylene oxide/propylene oxide block copolymer, organosilicone copolymer system (e.g., siloxane/polysulfone copolymer, siloxane/polyurethane, siloxane/polyurea copolymer, siloxane/polyamide copolymer, siloxane/polyimide copolymer, siloxane/polyamide/polyimide copolymer, siloxane/polyester copolymer, siloxane/polycarbonate copolymer, siloxane/polystyrene copolymer, siloxane/epoxide resin networks, etc.), hard block copolymer, other block copolymers, and/or combinations thereof. In an exemplary embodiment, the block copolymer films or layers comprise polystyrene-block-poly(ethylene oxide) (PS- b-PEO) and/or polystyrene and poly(methyl methacrylate) (PS-PMMA) although other block copolymers may be used in other exemplary embodiments.

[0039] A specific filler(s) may be added to a domain preferentially, thereby enhancing a characteristic of that domain of the block copolymer film. In exemplary embodiments disclosed herein, one or more fillers may be added to domains of multiple block copolymer films to thereby tailor the domains of the multiple block copolymer films for specific performance(s), (e.g., thermal management, electromagnetic interference (EMI) mitigation, electrical conductivity, thermal conductivity, EMI absorbing, magnetic, dielectric, and/or structural performance, etc.).

[0040] The multiple block copolymer films having the tailored domains may be assembled (e.g., laminated, stacked, etc.) into a multilayer structure (e.g., a laminate structure, etc.). The multilayer structure may be manufactured by a roll to roll process, spin casting, extrusion, curtain coating, 3D printing, additive manufacturing (e.g., fused deposition molding (FDM), stereolithography (SLA), laser direct structuring (LDS), etc.), molding, etc. [0041] In exemplary embodiments, vertical orientation control and preferential segregation/dispersion of fillers ( e.g ., functional nanoparticles, nickel cobalt, boron nitride, coated filler particles, etc.) may be used to tailor through-thickness domains of individual films or layers to have specific electrical, thermal, magnetic, dielectric, and/or structural performance. By controlling the domain size, shape, and structure within the multiple films or layers, the domains may be configured to create a pattern (e.g., a macropattern or hierarchical pattern based on patterns in the individual layers, etc.) or a gradient (e.g., an impedance gradient built across domains of the multilayer block copolymer films/layers by filler loading, etc.), etc. The domains may be configured such that the multiple layers have different functions. The domains within one layer may be configured (e.g., for controlled performance, etc.) different than or the same as the domains of one or more other layers.

[0042] The multiple films or layers may be configured differently from one another in exemplary embodiments in which the EMI absorbing structures comprise multiple films or layers. For example, the films or layers may have different thicknesses, may include different fillers (e.g., different materials, sizes, and/or shapes, etc.), may be made from different base or matrix materials, may have differently configured domains (e.g., tailored to have different functions, different sizes, different locations, etc.), etc. A multilayer film structure may comprise a plurality of films or layers, at least one or more of which comprises 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 comprise a first film or layer comprising a first base or matrix material and a first type of filler (e.g., thermally- conductive filler, etc.). The multilayer film structure may further comprise a second film or layer comprising a second base or matrix material different than the first base or matrix material, and a second type of filler (e.g., electrically-conductive and/or EMI absorbing filler, etc.) different than the first type of filler.

[0043] Exemplary embodiments may include EMI absorbing structures comprising polymer films/layers that are homogeneous or single-layer structures and/or that are not segregated block copolymers. For example, a homogeneous or single-layer film structure may include tailored through thickness domains spaced apart from each other within the homogenous or single-layer film structure to have specific electrical, thermal, magnetic, dielectric, and/or structural performance. Vertical orientation control and preferential segregation/dispersion of fillers (e.g., functional nanoparticles, nickel cobalt, boron nitride, coated filler particles, etc.) may be used to space apart and tailor the through-thickness domains within the homogeneous or single-layer film structure. By controlling the domain size, shape, and structure within the homogeneous or single-layer film structure, the domains may be configured to create a pattern (e.g., a macropattem or hierarchical pattern based on patterns in the individual layer, etc.) or a gradient (e.g., an impedance gradient built across domains of the individual layer by filler loading, etc.), etc. The domains may be configured such that the different spaced apart portions of the homogeneous or single-layer film structure have different functions. The domains within first and second spaced apart portions of the homogeneous or single-layer film structure may be configured (e.g., for controlled performance, etc. ) differently or the same as each other.

[0044] The domains within individual layers may be tailored to have specific characteristics, properties, functions, and/or performance, e.g., electrical, thermal, magnetic, dielectric, and/or structural, etc. The domains in the individual layers may create a pattern tailored or unique to that individual layer. The patterns of the individual layers may cooperate to define or create a macro-pattern (e.g., through the thickness of, etc.) in the multilayer film structure. For example, domains of one layer may be vertically aligned and/or at least partially overlapping with domains of another layer such that the vertically aligned and/or at least partially overlapping domains within the layers cooperate to define a pathway (e.g., electrically-conductive and/or thermally-conductive pathway, via, column, etc.) vertically through the thickness of the layers.

[0045] Block copolymer may be used as a base or matrix material in exemplary embodiments. For example, polystyrene-block-poly(ethylene oxide) (PS-b-PEO) may be used as the base or matrix material for only one, two, three, or all films of a multilayer film structure. Or, for example, polystyrene and poly(methyl methacrylate) (PS-PMMA) may be used as the base or matrix material for only one, two, three, or all films of a multilayer film structure. A different polymer may instead be selected that allows for larger domain sizes than the domain sizes achievable with polystyrene-block-poly(ethylene oxide) (PS-b-PEO) and/or polystyrene and poly(methyl methacrylate) (PS-PMMA). In other embodiments, different base or matrix materials may be used for one or more of the films, such as polystyrene-polyethylene block copolymer, another polystyrene-acrylate block copolymer, 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 copolymer (e.g., segmented polyester-polyether, segmented polyamide-polyether, etc.), polyolefinic block copolymer, ethylene oxide/propylene oxide block copolymer, organosilicone copolymer system ( e.g ., siloxane/polysulfone copolymer, siloxane/polyurethane, siloxane/polyurea copolymer, siloxane/polyamide copolymer, siloxane/polyimide copolymer, siloxane/polyamide/polyimide copolymer, siloxane/polyester copolymer, siloxane/polycarbonate copolymer, siloxane/polystyrene copolymer, siloxane/epoxide resin networks, etc.), hard block copolymer, other block copolymers, and/or combinations thereof.

[0046] A wide variety of fillers may be incorporated into a base or matrix material to tailor, modify, and/or functionally tune property(ies). The fillers may include functional nanoparticles, electrically-conductive fillers, thermally-conductive fillers, EMI or microwave absorbing fillers, magnetic fillers, dielectric fillers, coated fillers, combinations thereof, etc. The fillers may be added and mixed into a bulk material including the base or matrix material to thereby provide a mixture of the filler and base or matrix material. Example fillers include carbon black, boron nitride, nickel cobalt, air-filled microballoons, air-filled microbubbles, air-filled microspheres, carbonyl iron, iron silicide, iron particles, iron-chrome compounds, silver, an alloy containing 85% iron, 9.5% silicon and 5.5% aluminum, an alloy containing about 20% iron and 80% nickel, ferrites, magnetic alloys, magnetic powders, magnetic flakes, magnetic particles, nickel-based alloys and powders, chrome alloys, aluminum oxide, copper, zinc oxide, alumina, aluminum, graphite, ceramics, silicon carbide, manganese zinc, fiberglass, combinations thereof, etc. The fillers may comprise one or more of granules, spheroids, microspheres, ellipsoids, irregular spheroids, strands, flakes, powder, and/or a combination of any or all of these shapes. In addition, exemplary embodiments may also include different grades (e.g., different sizes, different purities, different shapes, etc.) of the same (or different) fillers.

[0047] In exemplary embodiments, films of a multilayer film structure may be made by casting, film extrusion, lamination, etc. In exemplary embodiments, filler density per layer may increase in a direction from a top layer to a bottom layer. Accordingly, the bottom layer may have the highest filler density while the top layer may have the lowest filler density.

[0048] Exemplary embodiments may include pyramidal structures comprising filled dielectric. The pyramidal structures may include air-filled particles (e.g., air- filled microballoons, air- filled microbubbles, air-filled microspheres, etc.) within the filled dielectric. The air- filled particles add air to the pyramidal structures, which decreases (e.g., controllably decreases, etc.) the dielectric constant. With the air-filled particles therein, the dielectric constant of the pyramidal structures may approximate the dielectric constant of foam and/or approach foam dielectric properties. Additionally or alternatively to being loaded or filled with air- filled particles, pyramidal and/or non-pyramidal structures may be covered or coated with polymer including air- filled particles (e.g., air- filled microballoons, air- filled microbubbles, air- filled microspheres, hollow glass spheres, microspheres, etc.) in other exemplary embodiments. For example, an exemplary embodiment may include pyramidal structures coated or covered with micro-balloon filled polymer, e.g., for environmental resistance, etc. In this example, the micro-balloon filled polymer may cover the pyramidal structures and define a planarization layer for filling in the spaces between the pyramidal structures. The inverse pyramidal structures of the planarization micro-balloon filled polymer layer may interleave or interlace with the pyramidal structures such that the combined pyramidal structures and planarization micro-balloon filled polymer layer have a generally flat sheet-like configuration. The planarization micro-balloon 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 micro-balloon filled polymer may comprise a low dielectric loss, low dielectric constant (e.g., less than 10, between 1 and 2, less than 1, etc.) material, such as Laird’s LoK low dielectric loss, low dielectric constant material including thermosetting plastic or silicone rubber and hollow glass spheres, etc. Alternatively, other materials (e.g., including materials that are not low dielectric loss, low dielectric constant materials and/or that do not include hollow glass spheres, etc.) may be used for defining a planarization layer and/or for covering or coating 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 other 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.

[0049] Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms, and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well- known processes, well-known device structures, and well-known technologies are not described in detail. In addition, advantages and improvements that may be achieved with one or more exemplary embodiments of the present disclosure are provided for purpose of illustration only and do not limit the scope of the present disclosure, as exemplary embodiments disclosed herein may provide all or none of the above mentioned advantages and improvements and still fall within the scope of the present disclosure.

[0050] Specific dimensions, specific materials, and/or specific shapes disclosed herein are example in nature and do not limit the scope of the present disclosure. The disclosure herein of particular values and particular ranges of values for given parameters are not exclusive of other values and ranges of values that may be useful in one or more of the examples disclosed herein. Moreover, it is envisioned that any two particular values for a specific parameter stated 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 could also be employed for the given parameter). For example, if Parameter X is exemplified herein to have value A and also exemplified to have value Z, it is envisioned that parameter X may have a range of values from about A to about Z. Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges. For example, if parameter X is exemplified herein to have values in the range of 1 - 10, or 2 - 9, or 3 - 8, it is also envisioned that Parameter X may have other ranges of values including 1 - 9, 1 - 8, 1 - 3, 1 - 2, 2 - 10, 2 - 8, 2 - 3, 3 - 10, and 3 - 9.

[0051] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. For example, when permissive phrases, such as “may comprise”,“may include”, and the like, are used herein, at least one embodiment comprises or includes the feature(s). As used herein, the singular forms“a”,“an” and“the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms“comprises,” “comprising,”“including,” and“having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0052] When an element or layer is referred to as being“on”,“engaged to”,“connected to” or“coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being“directly on,”“directly engaged to”,“directly connected to” or“directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion ( e.g .,“between” versus“directly between,”“adjacent” versus“directly adjacent,” etc.). As used herein, the term“and/or” includes any and all combinations of one or more of the associated listed items.

[0053] The term “about” when applied to values indicates that the calculation or the measurement allows some slight imprecision in the value (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If, for some reason, the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then“about” as used herein indicates at least variations that may arise from ordinary methods of measuring or using such parameters. For example, the terms“generally”,“about”, and“substantially” may be used herein to mean within manufacturing tolerances. Or for example, the term“about” as used herein when modifying a quantity of an ingredient or reactant of the invention or employed refers to variation in the numerical quantity that can happen through typical measuring and handling procedures used, for example, when making concentrates or solutions in the real world through inadvertent error in these procedures; through differences in the manufacture, source, or purity of the ingredients employed to make the compositions or carry out the methods; and the like. The term“about” also encompasses amounts that differ due to different equilibrium conditions for a composition resulting from a particular initial mixture. Whether or not modified by the term“about”, equivalents to the quantities are included.

[0054] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as“first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0055] Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”,“upper” and the like, may be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated 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 depicted in the figures. For example, if the device in the figures is turned over, elements described as“below” or“beneath” other elements or features would then be oriented“above” the other elements or features. Thus, the example term“below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0056] 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 stated uses, or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

CLAIMS What is claimed is:

1. A electromagnetic interference (EMI) absorber comprising EMI absorbing structures configured to suppress or reduce a probability of reflection of incident radiation through an aperture into a cavity or chamber when the EMI absorbing structures are disposed along an exterior to and/or an outside of the cavity or chamber.

2. The EMI absorber of claim 1, wherein the EMI absorbing structures are configured to suppress or reduce the probability of reflection of high frequency radiation at wide angles and/or radiation at stray frequencies through an automotive radar aperture into a cavity or chamber, whereby the EMI absorber placement may thereby allow for improved performance of electronics inside the cavity or chamber and remove stray frequencies.

3. The EMI absorber of claim 1 or 2, wherein the EMI absorbing structures comprise EMI absorbing cone-shaped and/or pyramidal structures.

4. The EMI absorber of claim 1 or 2, wherein the EMI absorbing structures comprise rectangular pyramids including rectangular bases configured such that the rectangular bases of adjacent rectangular pyramids contact each other substantially without any gaps or spaced distances between the rectangular bases of the adjacent rectangular pyramids.

5. The EMI absorber of claim 1 or 2, wherein:

the EMI absorbing structures comprise non-pyramidal structures that taper, decrease, and/or curve generally smoothly in width from a top towards a base; and/or

the EMI absorbing structures are configured to have a varying slope or taper with at least two or more slopes along sides thereof.

6. The EMI absorber of claim 1 or 2, wherein the EMI absorbing structures comprise pyramidal structures having a relatively gradual taper from a base towards a middle portion, a quicker taper from the middle portion towards a top, and less taper therefrom to the top of the pyramidal structure.

7. The EMI absorber of any one of claims 1 to 6, wherein the EMI absorbing structures comprise a filled dielectric.

8. The EMI absorber of claim 7, wherein the filled dielectric comprises a filled block copolymer system.

9. The EMI absorber of claim 7, wherein the filled dielectric comprises polydimethylsiloxane (PDMS) filled with carbon black.

10. The EMI absorber of any one of the preceding claims, wherein the EMI absorbing structures comprise rectangular pyramidal structures having bases of about a same size, and wherein one or more of the rectangular pyramidal structures have a different height than one or more other rectangular pyramidal structures.

11. The EMI absorber of any one of the preceding claims, wherein the EMI absorbing structures comprise air-filled particles for controllably decreasing dielectric constant of the EMI absorbing structures.

12. A device component comprising the EMI absorber of any one of the preceding claims, wherein the EMI absorbing structures are along the outside of the device component and configured for EMI mitigation and/or absorbing high frequency EMI.

13. The device component of claim 12, wherein the EMI absorbing structures are disposed along and protrude outwardly from one or more exterior portions of the device component.

14. The device component of claim 12 or 13, wherein the EMI absorbing structures comprise a first plurality of EMI absorbing structures disposed along an outer surface of a top wall of the device component, and a second plurality of EMI absorbing structures disposed along an outer surface of one or more sidewalls of the device component.

15. The device component of any one of claims 12 to 14, wherein:

the device component defines a chamber and an aperture into the chamber; and

the EMI absorbing structures are disposed along and/or define an entire top surface of the device component that defines the aperture into the chamber.

16. The device component of claim 15, wherein the EMI absorbing structures are disposed around an entire perimeter of the aperture.

17. The device component of claim 15 or 16, wherein the EMI absorbing structures are disposed along one or more inner surfaces of the device component within the chamber.

18. The device component of any one of claims 12 to 17, wherein the EMI absorbing structures are disposed along inner and outer surfaces of the device component, such that the EMI absorbing structures protrude inwardly and outwardly in opposite directions relative to the device component.

19. The device component of any one of claims 12 to 18, wherein:

the device component comprises an electronics housing or a board level shield;

the device component is configured for mitigating low frequency EMI; and

the EMI absorbing structures are configured for mitigating high frequency EMI.

20. A method of mitigating electromagnetic interference (EMI) comprising positioning EMI absorbing structures along an exterior to and/or along an outside of a cavity or chamber, wherein the EMI absorbing structures are configured to suppress or reduce a probability of reflection of incident radiation through an aperture into the cavity or chamber.