Low dielectric constant and low dielectric loss tangent laminate containing an aerogel layer

Abstract

The laminate includes one or more conductive layers and one or more electrically insulating layers bonded to the conductive layers. Each of the conductive layers may comprise at least 90% by weight copper. Each of the electrically insulating layers may include a layer of polymer aerogel. At least one of the opposing front and rear faces of the laminate has at least a portion of its surface defined by one of the conductive layers. TIFF2023525573000007.tif78129

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 63 / 025,947, filed May 15, 2020, which is incorporated by reference in its entirety without disclaimer.

[0002] A. Field of the Invention The present invention relates generally to copper clad laminates for use in high frequency (eg, 10-300 GHz) electrical applications such as communication systems, antenna systems, electrical amplifiers, radar systems, and the like. [Background technology]

[0003] B. Description of Related Art Copper clad laminates are often used in printed circuit boards (PCBs). Traditionally, copper clad laminates include one or more thin (e.g., less than 4.5 x 1000 inch (mil)) copper layers, at least one of which defines the outer surface of the laminate, and one or more insulating substrates that can provide structural support for the copper layers. To fabricate a PCB, each of the copper layers can be etched to define separate conductive lines or "traces" through which electricity can flow between different components bonded to the PCB.

[0004] The substrate properties of the copper clad laminate can affect the durability and electrical performance of the PCB. For example, the laminate may heat up when components are soldered to the PCB or during use of the PCB. Thermal expansion of the substrate, especially if its temperature rises above its glass transition temperature (Tg), can cause delamination of the copper layers and / or failure of the joints connecting the components to the PCB. In addition, the speed at which a signal can propagate through the PCB and the amount of electromagnetic energy of the signal dissipated in the PCB are affected by the dielectric constant (D k ) and dielectric loss tangent (D f ) is affected.

[0005] Substrates used in PCBs include woven or nonwoven glass fiber cloth dispersed in epoxy resin, polytetrafluoroethylene (PTFE), and paper (e.g., phenolic paper) impregnated with phenol-formaldehyde resin. Copper-clad laminates incorporating one or more of these substrates often have relatively low dielectric loss tangents (e.g., 0.0009–0.0018 at 10 GHz) that can mitigate dielectric loss, but their dielectric constants exceed 2.0. For example, copper-clad laminates with PTFE substrates typically have dielectric constants of 2.2–2.3 at 10 GHz. With a dielectric constant exceeding 2.0, PCBs using conventional copper-clad laminates may be unable to propagate signals at a speed sufficient to maintain signal integrity in high-frequency applications such as 5G communication systems and high-speed digital circuits. Therefore, there is a need in the art for copper-clad laminates with ultra-low dielectric constants suitable for use in PCBs. Summary of the Invention

[0006] To address this need in the art, some laminates of the present invention include one or more conductive layers, each comprising at least 90% copper by weight, and one or more electrically insulating layers bonded to the conductive layers. In some aspects, at least one of the electrically insulating layers can contain a porous material. In some aspects, the electrically insulating layers can each independently contain a porous material. In certain aspects, the porous material can be an open-cell porous material. In certain other aspects, the porous material can be a closed-cell porous material. In certain aspects, the porous material can be a foam. In certain aspects, the foam can be an organic or silicone foam. Non-limiting examples of organic foams include polyurethane, polystyrene, polyvinyl chloride, (meth)acrylic polymer, polyamide, polyimide, polyaramid, polyurea, polyester, polyolefin (e.g., polyethylene, polypropylene, ethylene propylene diene monomer (EPDM) foam, etc.), polyethylene terephthalate, polybutylene terephthalate, polyvinyl chloride, polyvinyl acetate, ethyl vinyl alcohol (EVOH), ethylene vinyl acetate (EVA), polymethyl methacrylate, polyacrylate, polycarbonate, polysulfonate, or synthetic rubber foam, or any combination thereof. In certain aspects, the foam may be polyurethane foam. In certain aspects, the porous material may be aerogel. In some laminates, each electrical insulation layer may include a layer of polymeric aerogel. Such aerogel layers may provide the laminate with an ultra-low dielectric constant (e.g., less than 2.0 at 10 GHz, e.g., 1.7 or less) and an ultra-low dielectric loss tangent (e.g., 0.002 or less at 10 GHz), making it suitable for high-frequency electrical applications.

[0007] The composition of the aerogel layer can enhance the heat resistance of the laminate, making it suitable for use in PCBs. For example, in some embodiments, for at least one of the electrical insulation layers, the layer of polymeric aerogel has a thermal decomposition temperature of at least 400°C, 450°C, or 500°C. In some embodiments, for at least one of the electrical insulation layers, the layer of polymeric aerogel comprises at least 90% by weight of an organic polymer and / or at least 90% by weight of a polyimide, polyamide, polyaramid, polyurethane, polyurea, and / or polyester. In some embodiments, for at least one of the electrical insulation layers, the layer of polymeric aerogel comprises an open cell structure and / or comprises micropores, mesopores, and / or macropores. In some embodiments, the aerogel layer has a pore volume, where at least 10%, at least 50%, at least 75%, or at least 95% of the pore volume is accounted for by micropores, mesopores, and / or macropores. For at least one of the electrical insulation layers, in some embodiments, the polymer aerogel layer has an average pore diameter of 2.0 nm to 50 nm or 50 nm to 5,000 nm, optionally 100 nm to 800 nm, 100 nm to 500 nm, 150 nm to 400 nm, 200 nm to 300 nm, or 225 nm to 275 nm. Thus, such a laminate may be able to withstand heat during PCB manufacturing (e.g., from soldering) and during PCB use.

[0008] Additionally, in some embodiments, at least one of the aerogel layers has a thickness of 20 mils or less, 12 mils or less, or 7 mils or less, e.g., 3 mils to 20 mils, 3 mils to 15 mils, 3 mils to 12 mils, or 3 mils to 7 mils. Such relatively thin aerogel layers can promote a low dielectric constant and low dissipation factor for the laminate. To illustrate, in some embodiments, at least one of the aerogel layers has: i) a dielectric constant at 10 GHz that is less than or equal to any one of, or between any two of, 3, 2.75, 2.5, 2.25, 2, 1.75, 1.6, 1.4, 1.3, 1.2, and 1.1; and / or a dielectric loss tangent at 10 GHz that is less than or equal to any one of, or between any two of, 0.005, 0.004, 0.003, 0.0025, 0.00225, 0.002, 0.00175, 0.0015, 0.00125, 0.001, 0.00075, and 0.0005. To illustrate, in some embodiments, the dielectric constant of the laminate is 2.0 or less, 1.9 or less, 1.8 or less, 1.75 or less, 1.7 or less, or 1.6 or less at 10 GHz, and / or the dielectric loss tangent of the laminate is 0.0025 or less, 0.00225 or less, 0.002 or less, 0.00175 or less, or 0.0015 or less at 10 GHz.

[0009] In some aspects, at least one or more of the electrical insulation layers may include fibers without the porous material of the present invention. In other aspects, at least one or more of the electrical insulation layers may include a combination of the porous material of the present invention and fibers (e.g., fibers dispersed or aligned within the porous material). The fibers may be natural, synthetic, semi-synthetic, or a combination thereof. The fibers may include plant, wood, animal, mineral, biological fibers, or a combination thereof. In some specific examples, the fibers may include rayon, bamboo, diacetate, triacetate fibers, polyester fibers, aramid fibers, or a combination thereof. In some embodiments, the fibers include metal fibers, carbon fibers, carbide fibers, glass fibers, mineral fibers, basalt fibers, or a combination thereof. In some embodiments, the fibers include thermoplastic polymer fibers, thermosetting polymer fibers, or a combination thereof. Non-limiting examples of thermoplastic fibers include polyethylene terephthalate (PET), the polycarbonate (PC) family of polymers, polybutylene terephthalate (PBT), poly(1,4-cyclohexylidenecyclohexane-1,4-dicarboxylate) (PCCD), glycol-modified polycyclohexyl terephthalate (PCTG), poly(phenylene oxide) (PPO), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), polymethyl methacrylate (PMMA), polyethyleneimine or polyether Examples of such fibers include poly(ethylene terephthalate) (PEI) and their derivatives, thermoplastic elastomers (TPE), terephthalic acid (TPA) elastomers, poly(cyclohexanedimethylene terephthalate) (PCT), polyethylene naphthalate (PEN), polyamide (PA), polysulfone sulfonate (PSS), sulfonate of polysulfone, polyether ether ketone (PEEK), polyether ketone ketone (PEKK), acrylonitrile butyldiene styrene (ABS), polyphenylene sulfide (PPS), copolymers thereof, or mixtures thereof.Non-limiting examples of thermosetting fibers include fibers of unsaturated polyester resin, polyurethane, polyoxybenzyl methylene glycol anhydride (e.g., Bakelite), urea formaldehyde, diallyl phthalate, epoxy resin, epoxy vinyl ester, polyimide, cyanate ester of polycyanurate, dicyclopentadiene, phenols, benzoxazine, copolymers thereof, or mixtures thereof. In some embodiments, the fibers are polyaramid, polyimide, polybenzoxazole, polyurethane, or mixtures thereof. In some embodiments, the fibers are vinylon. In some embodiments, the fibers are polyester fibers. In some embodiments, the fibers are nonwoven. In some embodiments, the fibers form a fiber matrix. In some embodiments, the fibers are 5 μm. 2 ~40,000μm 2 and an average length of 20 mm to 100 mm. In some embodiments, the cross-sectional area is 5, 10, 15, 20, 25, 50, 100, 150, 200, 250, 300, 350, 400, 450, or 500 μm 2, or any two of these values. In some embodiments, the fibers have an average length of about 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000, 1500, 2000, 3000, 4000, 5000 mm, or any two of these values. Various types of fiber bundles can be used depending on the intended application of the internally reinforced aerogel. For example, the bundles can be of carbon or ceramic fibers, or can be of carbon or ceramic precursor fibers, glass fibers, aramid fibers, or a mixture of different types of fibers. The bundles can contain any number of fibers. For example, a bundle may contain 400, 750, 800, 1375, 1000, 1500, 3000, 6000, 12000, 24000, 50000, or 60000 filaments. The fibers may have filament diameters of 5-24 microns, 10-20 microns, or 12-15 microns, or any range therebetween, or 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 microns, or any value therebetween. The fibers in the fiber bundle may be 7 μm or less. 2 ~800μm 2 , which is equivalent to an average diameter of a round fiber of 3 to 30 microns. In some embodiments, the fiber matrix comprises a felt, batting, nonwoven, or mat.

[0010] The conductive layers can have a thickness suitable for propagating an electrical signal. In some embodiments, at least one of the conductive layers has a thickness of 0.5 mils to 3 mils, 0.5 mils to 2 mils, or 0.5 mils to 0.9 mils, 1 mil to 2 mils, 1.4 mils, or about 0.7 mils. In some embodiments, at least one of the conductive layers has a thickness of 0.35 to 3 ounces per square foot (oz / ft 2 ) or 0.35~0.75oz / ft 2 , for example, about 0.5 oz / ft 2It has an areal density of

[0011] In some embodiments, the laminate includes one or more adhesive layers disposed between adjacent conductive and insulating layers. The adhesive layers can bond the other layers together and have properties that enhance the electrical performance of the laminate and reduce delamination. To illustrate, in some embodiments, at least one of the adhesive layers includes a fluoropolymer film, at least one of the adhesive layers includes a polyimide film, and / or at least one of the adhesive layers includes a B-stage epoxy. In some embodiments, at least one of the adhesive layers has a dielectric constant of 3.5 or less, 3.0 or less, 2.5 or less, or 2.25 or less at 10 GHz, and / or a dielectric loss tangent of 0.0040 or less, 0.0035 or less, 0.0030 or less, 0.0025 or less, 0.0020 or less, or 0.0015 or less at 10 GHz. In some embodiments, at least one of the adhesive layers has a decomposition temperature of 350° C. or higher, 375° C. or higher, 400° C. or higher, 450° C. or higher, or 500° C. or higher, and / or a glass transition temperature or melting point of 100° C. or higher, 150° C. or higher, 200° C. or higher, 225° C. or higher, 250° C. or higher, or 275° C. or higher. At least one of the adhesive layers, in some embodiments, has a thickness of 0.3 mils to 5 mils, 0.3 mils to 3.0 mils, 0.3 mils to 2.0 mils, 0.3 mils to 1.2 mils, or 0.75 to 1.25 mils.

[0012] The aerogel, and thus the laminate, can be relatively flexible. For example, in some embodiments, the laminate is arranged in a rolled form so that a portion of the front surface of the laminate faces a portion of the rear surface of the laminate. In some such embodiments, where the laminate is flexible enough to be arranged in a rolled form, the laminate can be used for flexible circuit boards. However, in other embodiments, the laminate can have a sufficiently high rigidity that it is not rollable. For example, in some embodiments, the laminate includes one or more reinforcing layers. Each of the reinforcing layers has a bending stiffness that is at least 10% greater than the bending stiffness of each of the conductive and insulating layers. In some embodiments, for at least one of the insulating layers, at least one of the reinforcing layers is optionally at least partially embedded in a layer of polymeric aerogel such that the Young's modulus of the insulating layer is at least 200 MPa. In some embodiments, at least one of the reinforcing layers includes one or more unidirectional, nonwoven, or woven sheets, each comprising fibers. In some embodiments, for at least one of the insulating layers, a plurality of fibers is optionally dispersed in the layer of polymeric aerogel such that the Young's modulus of the insulating layer is at least 200 MPa. At least one of the reinforcing layers, in some embodiments, comprises one or more paper sheets, however, in other embodiments, the laminate does not comprise fibers.

[0013] For at least one of the opposing front and rear surfaces of the laminate, in some embodiments, at least a portion, optionally at least a majority, of the surface is defined by one of the conductive layers. In some embodiments, the one or more conductive layers comprise two or more conductive layers, where optionally at least a portion of the front surface of the laminate is defined by one of the first conductive layers and at least a portion of the rear surface of the laminate is defined by one of the second conductive layers. The electrically insulating layers, in some embodiments, comprise two or more, optionally four or more, electrically insulating layers. In some embodiments, no conductive layer is disposed between adjacent ones of the electrically insulating layers. The laminate, in some embodiments, has a thickness of 5 mils to 100 mils, 5 mils to 75 mils, 5 mils to 50 mils, or 5 mils to 30 mils.

[0014] Some circuit boards of the present invention comprise some of the laminates of the present invention, and include a solder mask layer bonded to at least one of the front and rear surfaces such that the solder mask layer covers at least a majority of the surface. In some embodiments, the solder mask layer comprises at least 90% by weight of a polymer and / or has a thickness of 3.2 mils or less, 1.6 mils or less, or 0.8 mils or less. Some devices of the present invention comprise some of the circuit boards of the present invention and, optionally, an antenna electrically coupled to the circuit board. In some embodiments, the device is an electrical amplifier, a radar system, or a communications system.

[0015] Also disclosed is a method for making a layer of polymeric aerogel suitable for use in at least some of the laminates of the present invention. The method may include the steps of: (a) providing a monomer or combination of monomers in a solvent to form a solution; (b) polymerizing the monomers in the solution to form a polymeric gel matrix; and (c) subjecting the polymeric gel matrix to conditions sufficient to remove liquid from the polymeric gel matrix to form an aerogel having a polymeric matrix with an open cell structure. Step (b) may further include adding a curing agent to the solution to reduce the solubility of the formed polymer in the solution and to form macropores in the gel matrix, the formed macropores containing the liquid from the solution. The process may include casting the polymeric gel matrix in step (b) onto a support such that a layer of polymeric gel matrix is ​​formed on the support, wherein the aerogel in step (c) is in the form of a film.

[0016] The porous structure of the aerogel, including the amount and volume of macroporous, mesoporous, and microporous cells, can be controlled primarily by controlling the polymer / solvent dynamics during the formation of the polymer gel matrix. As an example, a curing agent can be added to the solution in step (b) to reduce the solubility of the polymer formed in the solution and form macropores in the gel matrix, with the resulting macropores containing liquid from the solution. Such a curing agent can be, for example, 1,4-diazabicyclo[2.2.2]octane. Alternatively, adding a curing agent such as triethylamine to the solution in step (b) to improve the solubility of the polymer formed in the solution results in the formation of a relatively small number of macropores in the gel matrix. In another example, when forming polyimide aerogels, increasing the ratio of rigid amines (e.g., p-phenylenediamine (p-PDA)) to more flexible diamines (e.g., 4,4'-oxydianiline (4,4'-ODA)) in the polymer backbone can favor the formation of macropores over smaller mesopores and micropores.

[0017] More details regarding the monomers, solvents, and processing conditions are outlined below, but the following can be adjusted to control the pore structure of the aerogel: (1) polymerization solvent; (2) polymerization temperature; (3) polymer molecular weight; (4) molecular weight distribution; (5) copolymer composition; (6) amount of branching; (7) amount of crosslinking; (8) branching method; (9) crosslinking method; (10) method used to form the gel; (11) type of catalyst used to form the gel; (12) chemical composition of the catalyst used to form the gel; (13) amount of catalyst used to form the gel; (14) temperature of gel formation; (15) type of gas flowing over the material during gel formation; (16) velocity of gas flowing over the material during gel formation; (17) ambient pressure during gel formation; (18) removal of dissolved gas during gel formation; (19) presence of solid additives in the resin during gel formation; (20) duration of the gel formation process; (21) substrate used in gel formation; and (22) at each stage of any solvent exchange process. (23) the composition of the solvent used at each stage of any solvent exchange process; (24) the time used at each stage of any solvent exchange process; (25) the residence time of the part at each stage of the solvent exchange process; (26) the flow rate of any solvent exchange solvent; (27) the type of flow of any solvent exchange solvent; (28) the agitation rate of any solvent exchange solvent; (29) the temperature used at each stage of any solvent exchange process; (30) the ratio of the volume of any solvent exchange solvent to the volume of the part; (31) the drying method; (32) the temperature at each stage of the drying process; (33) the pressure at each stage of the drying process; (34) the composition of the gas used at each stage of the drying process; (35) the gas flow rate during each stage of the drying process; (36) the temperature of the gas during each stage of the drying process; (37) the temperature of the part during each stage of the drying process; (38) the presence of an enclosure around the part during each stage of the drying process; (39) the type of enclosure around the part during drying; and / or (40) the solvent used at each stage of the drying process.

[0018] The term "aerogel" generally refers to a class of materials produced by forming a gel, removing a mobile interstitial solvent phase from the pores, and then replacing it with a gas or gaseous material. The gel and evaporation system can be controlled to minimize density, shrinkage, and pore collapse. Aerogels of the present invention can include macropores, mesopores, and / or micropores. In preferred aspects, macropores can account for a majority (e.g., greater than 50%) of the pore volume of the aerogel. In other alternative aspects, mesopores and / or micropores can account for a majority of the pore volume of the aerogel, such that macropores account for less than 50% of the pore volume of the aerogel. In some embodiments, aerogels of the present invention have low bulk densities (about 0.75 g / cm). 3 or less, preferably about 0.01 g / cm 3 ~0.5g / cm 3 ), high surface area (typically about 10 m 2 / g~1,000m 2 / g or more, preferably about 50m 2 / g~1000m 2 / g), high porosity (greater than about 20%, preferably greater than about 85%), and / or relatively large pore volume (greater than about 0.3 mL / g, preferably greater than about 1.2 mL / g).

[0019] The presence of macropores, mesopores, and / or micropores in the aerogels of the present invention can be determined by mercury intrusion porosimetry (MIP) and / or gas physisorption experiments. MIP tests can be used to measure mesopores and macropores (i.e., American Standard Testing Method (ASTM) D4404-10, Standard Test Method for Determination of Pore Volume and Pore Volume Distribution of Soil and Rock by Mercury Intrusion Porosimetry). Gas physisorption experiments can be used to measure micropores (i.e., ASTM D1993-03 (2008) Standard Test Method for Precipitated Silica - Surface Area by Multipoint BET Nitrogen).

[0020] The "decomposition temperature" of a material is the temperature at which 2%, 5%, or 10% of a sample of the material will decompose when heated in an environment elevated to that temperature. The decomposition temperature can be measured by placing a sample in a thermogravimetric analyzer (TGA), heating the sample from ambient temperature in the TGA (e.g., at a rate of 10°C / min), and recording the temperature at which the mass of the sample is 2%, 5%, or 10% lower than its initial mass as the decomposition temperature.

[0021] The term "coupled" is defined as connected, although not necessarily directly, and not necessarily mechanically. Two items that are "coupled" may be single with each other, or may be connected to each other through one or more intermediate components or elements.

[0022] The terms "a" and "an" are defined as one or more, unless this disclosure expressly requires otherwise.

[0023] The term "substantially," as understood by one of ordinary skill in the art, is defined as largely, but not necessarily entirely, what is specified (and includes what is specified; e.g., substantially 90 degrees includes 90 degrees, and substantially parallel includes parallel). In any disclosed embodiment, the terms "substantially," "approximately," and "about" may be substituted with "within [a percentage]" of what is specified, where the percentage is 0.1, 1, 5, or 10%.

[0024] The phrase "and / or" means and / or. To illustrate, A, B, and / or C includes: A only, B only, C only, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C. In other words, "and / or" operates as an inclusive or.

[0025] The terms "comprise" (and any form of "comprise," such as "comprises" and "comprising"), "have" (and any form of "has" and "having"), "include" (and any form of "includes" and "including"), and "contain" (and any form of "contains" and "containing") are open-ended linking verbs. Consequently, an apparatus that "comprises," "has," "includes," or "contains" one or more elements has those one or more elements, but is not limited to having only those one or more elements. Similarly, a method that "comprises," "has," "includes," or "contains" one or more steps has those one or more steps, but is not limited to having only those one or more steps.

[0026] Any aspect of any apparatus and method may consist of or consist essentially of any described elements, features, and / or steps, rather than comprise / have / include / contain. Thus, in any of the claims, the phrases "consisting of" or "consisting essentially of" may be used in place of any of the aforementioned open-ended linking verbs to modify a given claim from one that would otherwise use an open-ended linking verb.

[0027] Unless expressly prohibited by the nature of this disclosure or the embodiments, features of one embodiment may be applied to other embodiments even if not described or illustrated.

[0028] [The present invention 1001] one or more conductive layers, each comprising at least 90% by weight copper; one or more electrically insulating layers coupled to the conductive layer, each of the one or more electrically insulating layers comprising a layer of polymer aerogel; A laminate comprising: At least one of the opposing front and rear surfaces of the laminate has at least a portion of the surface defined by one of the conductive layers; Laminate. [The present invention 1002] the conductive layer includes two or more conductive layers; at least a portion of the front surface of the stack is defined by one of the first conductive layers; and At least a portion of the rear surface of the stack is defined by one of the second, conductive layers; The laminate of the present invention 1001. [The present invention 1003] The laminate of invention 1001 or 1002, wherein at least one of the conductive layers has a thickness of 0.5 mil to 3.0 mil or 0.5 mil to 0.9 mil. [The present invention 1004] The laminate of the present invention 1003, wherein at least one of the conductive layers has a thickness of about 0.7 mils. [The present invention 1005] At least one of the conductive layers must be 0.35 to 3.0 ounces per square foot (oz / ft 2 ) or 0.35~0.75oz / ft 2 The laminate of any one of 1001 to 1004 of the present invention, having an areal density of [The present invention 1006] At least one of the conductive layers has a thickness of about 0.5 oz / ft 2 The laminate of the present invention 1005 having an areal density of [The present invention 1007] The laminate of any one of claims 1001 to 1006, wherein for at least one of the electrical insulation layers, the layer of polymer aerogel comprises an open cell structure. [The present invention 1008] The laminate of any one of claims 1001 to 1007, wherein for at least one of the electrical insulation layers, the layer of polymer aerogel comprises micropores, mesopores, and / or macropores. [The present invention 1009] For at least one of the electrical insulating layers: The layer of polymer aerogel has a pore volume, and At least 10%, at least 50%, at least 75%, or at least 95% of the pore volume is micropores; The laminate of the present invention 1008. [The present invention 1010] For at least one of the electrical insulating layers: The layer of polymer aerogel has a pore volume, and At least 10%, at least 50%, at least 75%, or at least 95% of the pore volume is occupied by mesopores; The laminate of the present invention 1008. [The present invention 1011] For at least one of the electrical insulating layers: The layer of polymer aerogel has a pore volume, and At least 10%, at least 50%, at least 75%, or at least 95% of the pore volume is macropores; The laminate of the present invention 1008. [The present invention 1012] For at least one of the electrical insulating layers: The layer of polymer aerogel has a pore volume, and At least 10%, at least 50%, at least 75%, or at least 95% of the pore volume is occupied by micropores and / or mesopores; The laminate of the present invention 1008. [The present invention 1013] The laminate of any one of claims 1001 to 1007, wherein in at least one of the electrical insulating layers, the polymer aerogel layer has an average pore diameter of 2.0 nm to 50 nm. [The present invention 1014] The laminate of any one of claims 1001 to 1007, wherein for at least one of the electrical insulating layers, the layer of polymer aerogel has an average pore diameter of 50 nm to 5,000 nm. [The present invention 1015] 1014. The laminate of the present invention, wherein the average pore diameter is 100 nm to 800 nm, 100 nm to 500 nm, 150 nm to 400 nm, 200 nm to 300 nm, or 225 nm to 275 nm. [The present invention 1016] The laminate of any one of claims 1001 to 1015, wherein for at least one of the electrical insulating layers, the layer of polymer aerogel contains at least 90% by weight of an organic polymer. [The present invention 1017] The laminate of any one of claims 1001 to 1015, wherein for at least one of the electrical insulation layers, the layer of polymer aerogel comprises at least 90% by weight of polyimide, polyamide, polyaramid, polyurethane, polyurea, and / or polyester. [The present invention 1018] 1017. The laminate of claim 1017, wherein for at least one of the electrical insulation layers, the layer of polymer aerogel comprises at least 90% by weight of polyimide. [The present invention 1019] The laminate of any one of claims 1001 to 1018, wherein for at least one of the electrical insulation layers, the layer of polymer aerogel has a thickness of 20 mils or less. [The present invention 1020] 1019. The laminate of claim 10, wherein for at least one of the electrically insulating layers, the layer of polymeric aerogel has a thickness of 12 mils or less. [The present invention 1021] 1020. The laminate of claim 10, wherein for at least one of the electrically insulating layers, the layer of polymeric aerogel has a thickness of 7.0 mils or less. [The present invention 1022] The laminate of any of claims 1001 to 1018, wherein for at least one of the electrical insulation layers, the layer of polymer aerogel has a thickness of 3.0 to 20 mils, 3.0 mils to 15 mils, 3.0 mils to 12 mils, or 3.0 mils to 7.0 mils. [The present invention 1023] The laminate of any one of claims 1001 to 1022, wherein for at least one of the electrical insulating layers, the polymer aerogel layer has a decomposition temperature of 400°C or higher, 450°C or higher, or 500°C or higher. [The present invention 1024] one or more adhesive layers disposed between adjacent ones of the electrically conductive and electrically insulating layers, respectively; The laminate of any one of 1001 to 1023 of the present invention, comprising: [The present invention 1025] The laminate of claim 1024, wherein at least one of the adhesive layers comprises a fluoropolymer film. [The present invention 1026] 1024. The laminate of claim 1024, wherein at least one of the adhesive layers comprises a polyimide film. [The present invention 1027] 1024. The laminate of claim 10, wherein at least one of the adhesive layers comprises a B-stage epoxy. [The present invention 1028] The laminate of any one of claims 1024 to 1027, wherein at least one of the adhesive layers has a dielectric constant of 3.5 or less, 3.0 or less, 2.5 or less, or 2.25 or less at 10 GHz. [The present invention 1029] The laminate of any one of claims 1024 to 1028, wherein at least one of the adhesive layers has a dielectric dissipation factor of 0.0040 or less, 0.0035 or less, 0.0030 or less, 0.0025 or less, 0.0020 or less, or 0.0015 or less at 10 GHz. [The present invention 1030] The laminate of any one of claims 1024 to 1029, wherein at least one of the adhesive layers has a decomposition temperature of 350°C or higher, 375°C or higher, 400°C or higher, 450°C or higher, or 500°C or higher. [The present invention 1031] The laminate of any one of inventions 1024 to 1030, wherein at least one of the adhesive layers has a glass transition temperature or melting point of 100°C or higher, 150°C or higher, 200°C or higher, 225°C or higher, 250°C or higher, or 275°C or higher. [The present invention 1032] The laminate of any of inventions 1024 to 1031, wherein at least one of the adhesive layers has a thickness of 0.3 mil to 5 mil, 0.3 mil to 3.0 mil, 0.3 mil to 2.0 mil, 0.3 mil to 1.2 mil, or 0.75 to 1.25 mil. [The present invention 1033] the electrically insulating layer includes two or more electrically insulating layers; and No conductive layer is disposed between adjacent ones of the electrically insulating layers; A laminate according to any one of claims 1001 to 1032 of the present invention. [The present invention 1034] The laminate of any one of inventions 1001 to 1033, having a thickness of 5.0 mil to 100 mil, 5.0 mil to 75 mil, 5.0 mil to 50 mil, or 5.0 mil to 30 mil. [This invention 1035] The laminate of any one of claims 1001 to 1034, which is arranged in a roll shape so that a part of the front surface of the laminate faces a part of the rear surface of the laminate. [The present invention 1036] The laminate of any one of 1001 to 1035 of the present invention, which has a dielectric constant of 2.0 or less, 1.9 or less, 1.8 or less, 1.7 or less, or 1.6 or less at 10 GHz. [This invention 1037] 1036. A laminate of the present invention having a dielectric constant of 1.75 or less. [The present invention 1038] The laminate of any one of claims 1001 to 1037, having a dielectric loss tangent of 0.0025 or less, 0.00225 or less, 0.002 or less, 0.00175 or less, or 0.0015 or less at 10 GHz. [This invention 1039] The laminate of the present invention 1038, having a dielectric loss tangent of 0.002 or less. [The present invention 1040] one or more reinforcing layers; each of the reinforcing layers has a bending stiffness that is at least 10% greater than the bending stiffness of each of the electrically conductive and electrically insulating layers; and / or at least one of the reinforcing layers is at least partially embedded in a layer of polymer aerogel such that for at least one of the electrical insulation layers, the Young's modulus of the electrical insulation layer is at least 200 MPa; and / or For at least one of the electrical insulation layers, the plurality of fibers are dispersed in the layer of polymer aerogel such that the Young's modulus of the electrical insulation layer is at least 200 MPa. A laminate according to any one of claims 1001 to 1039 of the present invention. [This invention 1041] At least one of the reinforcing layers is one or more unidirectional, woven, or nonwoven sheets containing fibers, and / or one or more paper sheets; The laminate of the present invention 1040, comprising: [The present invention 1042] A laminate according to any one of claims 1001 to 1040 of the present invention, which does not contain fibers. [This invention 1043] Any one of the laminates of the present invention 1001 to 1041, a solder mask layer bonded to at least one of the front and rear surfaces such that the solder mask layer covers at least a majority of the surface, the solder mask layer comprising at least 90% by weight of a polymer; and a circuit board. [This invention 1044] The circuit board of the present invention 1043, wherein the thickness of the solder mask layer is 3.2 mils or less, 1.6 mils or less, or 0.8 mils or less. [This invention 1045] An apparatus including the circuit board of the present invention 1043 or 1044, an antenna electrically coupled to the circuit board; and / or An apparatus that is an electrical amplifier, a radar system, or a communications system. Some details relating to the aforementioned aspects and others are set forth below. [Brief explanation of the drawings]

[0029] The following drawings are by way of example, not limitation. For purposes of brevity and clarity, every feature of a given structure is not always labeled in every figure in which that structure appears. Identical reference numbers do not necessarily refer to identical structures. Rather, identical reference numbers, as well as non-identical reference numbers, may be used to refer to similar features or features with similar functionality.

[0030] [Figure 1]Figure 1A is a top view of a first embodiment of a laminate of the present invention, including a polymeric aerogel layer disposed between two copper-containing layers, and Figure 1B is a cross-sectional side view of the laminate of Figure 1A taken along line 1B-1B. [Figure 2] Figure 2A is a cross-sectional side view of a second embodiment of a laminate of the present invention, comprising two polymeric aerogel layers disposed between two copper-containing layers, and Figure 2B is a cross-sectional side view of a third embodiment of a laminate of the present invention, comprising four polymeric aerogel layers disposed between two copper-containing layers. [Figure 3] Figure 3A is a cross-sectional side view of a fourth embodiment of a laminate of the present invention, which includes a reinforcing layer embedded in a polymeric aerogel layer, and Figure 3B is a cross-sectional side view of a fifth embodiment of a laminate of the present invention, which includes a non-embedded reinforcing layer in addition to a polymeric aerogel layer and a copper-containing layer. [Figure 4] FIG. 1B is a perspective view of the laminate of FIG. 1A in roll form. [Figure 5A] 5A is a top view of one of the circuit boards of the present invention including the laminate of FIG. 1A, in which the upper copper-containing layer of the laminate has been etched to define separate conductive paths. FIG. 5A omits the solder mask layer of the circuit board. [Figure 5B] 5B is a top view of the circuit board of FIG. 5A, with a solder mask layer covering at least a majority of the top surface of the stack. [Figure 5C] 5C is a cross-sectional side view of the circuit board of FIG. 5A taken along line 5C-5C of FIG. 5B. [Figure 6] 5B is a schematic diagram of one of the devices of the present invention including the circuit board of FIG. 5A electrically coupled to an antenna. [Figure 7] 1 is a pore diameter distribution for a first non-limiting aerogel of the present invention. [Figure 8] 1 is a pore diameter distribution for a second non-limiting aerogel of the present invention. [Figure 9] 10 is a pore diameter distribution for a third non-limiting aerogel of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] Detailed Description A. Copper-clad laminates, circuit boards, and devices incorporating the same 1A and 1B, shown is a first embodiment 10a of a laminate of the present invention. Laminate 10a can include one or more conductive layers 14 and one or more electrically insulating layers 18, such as 1, 2, 3, 4, 5, or 6 or more, or between any two numbers of conductive layers and 1, 2, 3, 4, 5, or 6 or more, or between any two numbers of electrically insulating layers. As shown, laminate 10a includes two conductive layers 14 and one electrically insulating layer 18 disposed therebetween. However, in other embodiments, laminate (e.g., 10b or 10c) can include multiple electrically insulating layers 18, such as two (FIG. 2A) or four (FIG. 2B) electrically insulating layers.

[0032] For at least one (e.g., each) of the opposing front and rear surfaces (22a and 22b) of a laminate (e.g., 10a-10c), at least a portion (e.g., at least a majority, including up to all) of the surface (e.g., the planar region of the surface) can be defined by one of the conductive layers 14; as shown, substantially all of the front and rear surfaces are defined by first and second conductive layers, respectively, with all of the electrically insulating layers 18 disposed between the first and second conductive layers. In this manner, one or more of the conductive layers 14 can be exposed so that circuits can be fabricated therefrom (e.g., by etching, as described below), with the electrically insulating layers 18 supporting and insulating the conductive layers. To further facilitate such circuit fabrication, in some embodiments where there are multiple electrically insulating layers 18, no conductive layers 14 are disposed between adjacent ones of the electrically insulating layers.

[0033] Each of the conductive layers 14 can include copper, which can enhance electrical conductivity. For example, each of the conductive layers 14 can include, or between any two of the following values: 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% copper by weight. The thickness 30 of each of the conductive layers 14 can facilitate manufacturability and suitable electrical properties. For example, at least one (e.g., each) of the conductive layers 14 may have a thickness 30 that is equal to or less than any one of 4.5, 4.0, 3.5, 3.0, 2.5, 2.0, 1.5, 1.0, 0.9, 0.8, 0.7, 0.6, or 0.5 mils, or between any two of these values ​​(e.g., 0.5-3.0 mils, e.g., 0.5-2 mils, e.g., 0.5-0.9 mils, about 1.4 mils, or about 0.7 mils). The areal density of each of the conductive layers 14 may be 3.0, 2.5, 2.0, 1.5, 1.0, 0.75, 0.50, or 0.25 ounces per square foot (oz / ft 2 ) or between any two values ​​(e.g., 0.35 to 3.0 oz / ft 2 , e.g. 0.35~0.75oz / ft 2 or approximately 0.5 oz / ft 2 ) can be relatively thick (e.g., 1.5 mils or more and / or 1.1 oz / ft 2 A conductive layer 14 with a larger areal density (or greater) can be used to accommodate larger power loads.

[0034] In some aspects, each of the electrical insulation layers 18 can contain a porous material. In certain aspects, the porous material can be an open-cell porous material. In certain other aspects, the porous material can be a closed-cell porous material. In certain aspects, the porous material can be a foam. In certain aspects, the foam can be an organic or silicone foam. Non-limiting examples of organic foams can include polyurethane, polystyrene, polyvinyl chloride, (meth)acrylic polymer, polyamide, polyimide, polyaramid, polyurea, polyester, polyolefin (e.g., polyethylene, polypropylene, ethylene propylene diene monomer (EPDM) foam, etc.), polyethylene terephthalate, polybutylene terephthalate, polyvinyl chloride, polyvinyl acetate, ethyl vinyl alcohol (EVOH), ethylene vinyl acetate (EVA), polymethyl methacrylate, polyacrylate, polycarbonate, polysulfonate, or synthetic rubber foam, or any combination thereof. In certain aspects, the foam can be polyurethane foam. In certain aspects, the porous material can be an aerogel. In some aspects, each of the electrical insulation layers 18 can include a layer of polymer aerogel. To promote desired dielectric properties (e.g., low dielectric constant and low dissipation factor), each aerogel layer 18 can be relatively thin. For example, the thickness 34 of at least one (e.g., each) aerogel layer 18 can be equal to or less than any one of 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9.0, 8.0, 7.0, 6.0, 5.0, 4.0, or 3.0 mils, or between any two of these values, preferably equal to or less than 12 mils (e.g., about 10 mils) or equal to or less than 7.0 mils (e.g., about 5.0 mils).In some embodiments, each of the electrically insulating layers 18 has i) a dielectric constant at 10 GHz that is less than or equal to any one of, or between any two of, 3, 2.75, 2.5, 2.25, 2, 1.75, 1.6, 1.4, 1.3, 1.2, and 1.1; and / or a dielectric loss tangent at 10 GHz that is less than or equal to any one of, or between any two of, 0.005, 0.004, 0.003, 0.0025, 0.00225, 0.002, 0.00175, 0.0015, 0.00125, 0.001, 0.00075, and 0.0005.

[0035] Each polymeric aerogel layer 18 can have micropores, mesopores, and / or macropores. Micropores, mesopores, and / or macropores (e.g., micropores, mesopores, micropores and mesopores, or macropores) can account for any one or more of 10%, 25%, 50%, 75%, or 95% of the pore volume of each aerogel layer 18. The average pore volume of each aerogel layer 18 can be any one or more of, or between any two of, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 800, 1,000, 2,000, 3,000, 4,000, or 5,000 nm.

[0036] Each of the aerogel layers 18 can also be heat resistant, such that the stack can withstand heating during circuit board fabrication (e.g., during soldering) and when the stack is in use (e.g., from heat generated by electricity flowing through the stack). For example, the decomposition temperature of at least one (e.g., each) of the aerogel layers 18 can be equal to or greater than any one of 400, 425, 450, 475, 500, 525, 550, 575, or 600°C, or between any two values ​​(e.g., equal to or greater than 450°C). Materials and fabrication processes for the polymer aerogel layers are described in Sections B and C below.

[0037] In some aspects, each of the electrical insulation layers 18 can include fibers without the porous material of the present invention. In other aspects, each of the electrical insulation layers 18 can include a combination of the porous material of the present invention and fibers (e.g., fibers dispersed or aligned within the porous material). The fibers can be natural, synthetic, semi-synthetic, or a combination thereof. The fibers can include plant, wood, animal, mineral, biological fibers, or a combination thereof. In some specific examples, the fibers can include rayon, bamboo, diacetate, triacetate fibers, polyester fibers, aramid fibers, or a combination thereof. In some embodiments, the fibers include metal fibers, carbon fibers, carbide fibers, glass fibers, mineral fibers, basalt fibers, or a combination thereof. In some embodiments, the fibers include thermoplastic polymer fibers, thermoset polymer fibers, or a combination thereof. Non-limiting examples of thermoplastic fibers include polyethylene terephthalate (PET), the polycarbonate (PC) family of polymers, polybutylene terephthalate (PBT), poly(1,4-cyclohexylidenecyclohexane-1,4-dicarboxylate) (PCCD), glycol-modified polycyclohexyl terephthalate (PCTG), poly(phenylene oxide) (PPO), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), polymethyl methacrylate (PMMA), polyethyleneimine or polyether Examples of such fibers include poly(ethylene terephthalate) (PEI) and their derivatives, thermoplastic elastomers (TPE), terephthalic acid (TPA) elastomers, poly(cyclohexanedimethylene terephthalate) (PCT), polyethylene naphthalate (PEN), polyamide (PA), polysulfone sulfonate (PSS), sulfonate of polysulfone, polyether ether ketone (PEEK), polyether ketone ketone (PEKK), acrylonitrile butyldiene styrene (ABS), polyphenylene sulfide (PPS), copolymers thereof, or mixtures thereof.Non-limiting examples of thermosetting fibers include fibers of unsaturated polyester resin, polyurethane, polyoxybenzyl methylene glycol anhydride (e.g., Bakelite), urea formaldehyde, diallyl phthalate, epoxy resin, epoxy vinyl ester, polyimide, cyanate ester of polycyanurate, dicyclopentadiene, phenols, benzoxazine, copolymers thereof, or mixtures thereof. In some embodiments, the fibers are polyaramid, polyimide, polybenzoxazole, polyurethane, or mixtures thereof. In some embodiments, the fibers are vinylon. In some embodiments, the fibers are polyester fibers. In some embodiments, the fibers are nonwoven. In some embodiments, the fibers form a fiber matrix. In some embodiments, the fibers are 5 μm. 2 ~40,000μm 2 and an average length of 20 mm to 100 mm. In some embodiments, the cross-sectional area is 5, 10, 15, 20, 25, 50, 100, 150, 200, 250, 300, 350, 400, 450, or 500 μm 2, or any two of these values. In some embodiments, the fibers have an average length of about 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000, 1500, 2000, 3000, 4000, 5000 mm, or any two of these values. Various types of fiber bundles can be used depending on the intended application of the internally reinforced aerogel. For example, the bundles can be of carbon or ceramic fibers, or can be of carbon or ceramic precursor fibers, glass fibers, aramid fibers, or a mixture of different types of fibers. The bundles can contain any number of fibers. For example, a bundle may contain 400, 750, 800, 1375, 1000, 1500, 3000, 6000, 12000, 24000, 50000, or 60000 filaments. The fibers may have filament diameters of 5-24 microns, 10-20 microns, or 12-15 microns, or any range therebetween, or 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 microns, or any value therebetween. The fibers in the fiber bundle may be 7 μm or less. 2 ~800μm 2 , which is equivalent to an average diameter of a round fiber of 3 to 30 microns. In some embodiments, the fiber matrix comprises a felt, batting, nonwoven, or mat.

[0038] The laminate may also include one or more adhesive layers 26, e.g., any one or more of 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 adhesive layers, or between any two of these, for bonding the other layers of the laminate to one another. Each of the adhesive layers 26 may be disposed between adjacent ones of the other laminate layers (e.g., the electrically conductive layer 14 and the electrically insulating layer 18). Bonding may be achieved by stacking the layers (e.g., 14, 18, 26) and applying heat and / or pressure (e.g., with a press) to the stack, optionally such that the temperature exceeds the glass transition temperature of the adhesive layer 26.

[0039] The adhesive layers 26 may have a composition that reduces the risk of delamination, such as through heat resistance. For example, at least one (e.g., each) of the adhesive layers 26 may have a decomposition temperature equal to or greater than any one of, or between any two of, 350, 375, 400, 425, 450, or 500°C. In addition, at least one (e.g., each) of the adhesive layers 26 may have a glass transition temperature or melting point equal to or greater than any one of, or between any two of, 100, 150, 175, 200, 225, 250, or 275°C. The adhesive layers 26 may also promote a low dielectric constant and dissipation factor for the laminate. For example, at least one (e.g., each) of adhesive layers 26 may have a dielectric constant less than or equal to any one of 3.5, 3.25, 3.0, 2.75, 2.5, or 2.25, or between any two values ​​(e.g., less than or equal to 3.0), and / or a dissipation factor less than or equal to any one of 0.0040, 0.0035, 0.0030, 0.0025, 0.0020, or 0.0015, or between any two values ​​(e.g., less than or equal to 0.00375), measured at 10 GHz. Exemplary adhesives suitable for adhesive layer 26 include fluoropolymer films, polyimide films, and B-stage epoxies. The adhesive for adhesive layer 26 can be a commercially available adhesive, such as DuPont™ FEP Film, Pyralux™ HT, and Pyralux™ GPL, and Toyochem Co., LTD. (Tokyo, Japan) TSU510S-A, DuPont™ Teflon FEP, etc. The thickness 38 of at least one (e.g., each) of adhesive layers 26 can be equal to or less than any one of 5.0, 4.0, 3.0, 2.0, 1.25, 1.0, 0.75, 0.60, 0.50, 0.40, or 0.30 mils, or between any two values ​​(e.g., 0.3-0.7 mil, e.g., about 0.5 mil), which can promote adhesion while promoting desired dielectric properties.

[0040] The laminate is suitable for use in circuit boards and can have a relatively thin (e.g., to promote a low dielectric constant and dissipation factor) total thickness 42 (e.g., measured between the front and rear surfaces (22a and 22b)). For example, thickness 42 can be equal to or less than any one of 100, 75, 50, 40, 30, or 20 mils, or between any two values ​​(e.g., 5 to 30 mils).

[0041] The laminate may have dielectric properties suitable for use in high-frequency applications (e.g., signal frequencies between 10 and 300 GHz). For example, the laminate may have an ultra-low dielectric constant, such as less than or equal to any one of 2.0, 1.9, 1.8, 1.7, or 1.6 at 10 GHz, or between any two values ​​(e.g., less than or equal to 1.75), so that electrical signals can propagate through the laminate at relatively high speeds. In addition, the laminate may have a low dissipation factor to reduce dielectric loss, such as less than or equal to any one of 0.0025, 0.00225, 0.002, 0.00175, or 0.0015 at 10 GHz, or between any two values ​​(e.g., less than or equal to 0.002).

[0042] In some embodiments, the laminate may include reinforcement, such as a plurality of fibers, to increase strength and / or stiffness (e.g., for rigid circuit board applications). For example, referring to FIGS. 3A and 3B, shown are laminates 10d and 10e, which are substantially similar to laminate 10a, except that each includes one or more reinforcement layers 46, e.g., any one or more of 1, 2, 3, 4, 5, 6, 7, or 8 reinforcement layers, or between any two of these. At least one (e.g., each) of the reinforcement layers 46 may include one or more sheets. At least one (e.g., each) of the sheets may optionally be a unidirectional, woven, and / or nonwoven sheet comprising fibers dispersed in a thermoplastic or thermosetting resin (e.g., a resin having a different structure (e.g., nonporous) or composition than aerogel layer 18). The sheets of reinforcement layer 46 may also be substantially fiber-free (e.g., a polymer film, such as a fluoropolymer film). When including multiple sheets, reinforcement layer 46 may be a reinforced laminate. Additionally or alternatively, at least one (e.g., each) of the reinforcing layers 46 may include a paper sheet, optionally containing cellulose fibers, vinylon fibers, polyester fibers, polyolefin fibers, and / or polypropylene fibers. Suitable papers for the reinforcing layer 46 are commercially available from Hirose Paper Mfg. Co. (Kochi, Japan) or Hirose Paper North America (Macon, Georgia, USA).

[0043] As shown, for at least one of the aerogel layers 18, at least one of the reinforcing layers 46 is embedded in the aerogel layer ( FIG. 3A ). While a single reinforcing layer 46 is embedded in the aerogel layer 18 as shown, in other embodiments, multiple reinforcing layers (e.g., any number of 2, 3, 4, 5, or 6 or more, or any number between) can be embedded in the aerogel layer. Additionally or alternatively, one or more reinforcing layers 46 need not be embedded in one of the aerogel layers 18 but can be adhered to other stack layers via one or more adhesive layers 26 (e.g., can be disposed between adjacent ones of the adhesive layers). The reinforcing or support layer 46 can be embedded in or bonded to the aerogel layer 18, as described in Section C.

[0044] Additionally, while laminates 10d and 10e are reinforced with reinforcing layer 46 as shown, in some embodiments, at least one (e.g., each) of aerogel layers 18 can optionally include reinforcing fibers (e.g., discontinuous or chopped fibers not arranged in a sheet) dispersed throughout the aerogel layer such that the volume of the fibers is equal to or greater than any one of, or between any two of, 0.1%, 10%, 20%, 30%, 40%, or 50% of the volume of the layer of polymeric aerogel. However, in some embodiments, the laminate does not include fibers (e.g., to increase flexibility).

[0045] Suitable fibers include glass fibers, carbon fibers, aramid fibers, thermoplastic fibers, thermoset fibers, ceramic fibers, basalt fibers, rock wool fibers, steel fibers, cellulose fibers, etc. The average filament cross-sectional area of ​​the fibers used for reinforcement is 7, 15, 30, 60, 100, 200, 300, 400, 500, 600, 700, or 800 μm. 2or between any two values; for example, for fibers having a circular cross section, the average diameter of the fibers can be any one of 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 μm or between any two values ​​(e.g., 5 to 24 μm, e.g., 10 to 20 μm or 12 to 15 μm).

[0046] Non-limiting examples of thermoplastic polymers that may be used as the material in which the fibers are dispersed in the reinforcing layer 46 and / or for the polymeric reinforcing fibers include polyethylene terephthalate (PET), polycarbonate (PC), polybutylene terephthalate (PBT), poly(1,4-cyclohexylidenecyclohexane-1,4-dicarboxylate) (PCCD), glycol-modified polycyclohexyl terephthalate (PCTG), poly(phenylene oxide) (PPO), polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), polymethyl methacrylate (PMMA), polyethyleneimine, or polyetherimide. Examples of suitable polymers include polyethylene terephthalate (PEI) and derivatives thereof, thermoplastic elastomers (TPE), terephthalic acid (TPA) elastomers, poly(cyclohexanedimethylene terephthalate) (PCT), polyethylene naphthalate (PEN), polyamide (PA), polysulfone sulfonate (PSS), sulfonate of polysulfone, polyether ether ketone (PEEK), polyether ketone ketone (PEKK), acrylonitrile butyldiene styrene (ABS), polyphenylene sulfide (PPS), copolymers thereof, polyesters or derivatives thereof, polyamides or derivatives thereof (e.g., nylon), or mixtures thereof.

[0047] Non-limiting examples of thermoplastic fibers that may be used as the dispersed material in the reinforcing layer 46 and / or for the polymeric reinforcing fibers include unsaturated polyester resins, polyurethanes, polyoxybenzyl methylene glycol anhydrides (e.g., Bakelite), urea formaldehyde, diallyl phthalate, epoxy resins, epoxy vinyl esters, polyimides, cyanate esters of polycyanurates, dicyclopentadiene, phenols, benzoxazines, copolymers thereof, or mixtures thereof.

[0048] Such reinforcement can increase laminate strength and stiffness. For example, each of the electrically insulating layers 18, in which the aerogel layers are reinforced (e.g., by one or more embedded sheets and / or fiber reinforcement dispersed throughout the aerogel), can have a tensile strength of, or between, any one of 5, 10, 15, 20, or 25 MPa, and / or a Young's modulus of, or between, any one of 200, 225, 250, 275, 300, 325, or 350 MPa. Each of the reinforced layers 46 can also be stiffer than the other laminate layers; for example, the bending stiffness of each of the reinforced layers can be 10%, 20%, 30%, or 40% greater than, or between, any one of the bending stiffnesses of the conductive layer 14 and the electrically insulating layer 18.

[0049] Further description of suitable reinforcement for the aerogel layer 18 is provided in US Pat. No. 10,500,557 to Sakaguchi et al., which is incorporated herein by reference in its entirety.

[0050] The laminates (e.g., 10a-10e) can be rigid or flexible. For example, referring to FIG. 4, the laminate (whether reinforced as described above or not) can be placed in roll form 48 with an inner diameter 50 of 10 cm, 8 cm, 5 cm, 4 cm, 2 cm, or 1 cm or less, or between any two of these values, without undergoing permanent deformation. Even if flexibility does not reach the level shown in this example, it can be provided by the materials of the laminate's conductive layer, aerogel layer, and other layers (if present) and / or their relatively thin thicknesses (e.g., as described above). When in roll form 48, a portion of the front surface 22a of the laminate can face a portion of the rear surface 22b. The laminate can have a protective film 52 removably disposed on at least one of its front and rear surfaces (22a and 22b) (to protect one or more of the conductive layers 14). The protective film 52 can be removed from the laminate, for example, by peeling it off the laminate. Such a protective film does not form part of the laminate.

[0051] Such flexible laminates may be suitable for use in flexible circuit boards. However, in other embodiments, the laminate may have a higher stiffness (e.g., such that it cannot be placed in such a rolled form without undergoing permanent deformation and / or breakage), which may be provided by the aforementioned reinforcement. Such laminates may be suitable for use in rigid circuit boards.

[0052] Some of the laminates (e.g., 10a-10e) of the present invention can be incorporated into a circuit board. For example, referring to FIGS. 5A-5C, shown is a circuit board 54 including laminate 10a. As shown, at least one (e.g., each) of conductive layers 14 defining at least a portion of one of the front and rear surfaces (22a and 22b) can be etched such that the conductive layer defines one or more conductive lines 56. The etching can remove material from conductive layer 14; as a result, the etched layer can define a smaller surface area (e.g., 90%, 80%, 70%, 60%, 50%, or 40% or less, or between any two values) of the front and / or rear surfaces (22a and 22b) than that defined by polymer aerogel layer 18 and / or adhesive layer 26, respectively (e.g., where such surface area is measured as planar area).

[0053] The circuit board 54 can include one or more solder mask layers 58, each coupled to a respective one of the front and back surfaces (22a and 22b) such that the solder mask layer covers at least a majority of the surface (FIGS. 5B and 5C). Each of the solder mask layers 58 can protect the outermost conductive layer 14 (e.g., from corrosion, damage, and / or shorting). For example, each solder mask layer 58 can include a polymer (e.g., any of the foregoing) such that the polymer comprises at least one of, or between, any two of the following values: 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%. To promote such protection while maintaining adequate manufacturability and / or electrical properties, the thickness 62 of each of the solder mask layers 58 may be equal to or less than any one of 3.2, 3.0, 2.8, 2.6, 2.4, 2.2, 2.0, 1.8, 1.6, 1.4, 1.2, 1.0, or 0.8 mils, or between any two values ​​(e.g., 0.8-3.2 mils). Each of the solder mask layers 58 may cover less than all of the surface (e.g., 22a or 22b) to which it is bonded, such that at least a portion of the conductive layer 14 is exposed (e.g., so that a component may electrically connect thereto) (FIG. 5B).

[0054] Some of the circuit boards (e.g., 54) of the present invention can be incorporated into devices (e.g., 66) used for high frequency (e.g., 10-300 GHz) applications. For example, referring to FIG. 6, shown is device 66 including circuit board 54 and antenna 70 electrically coupled to the circuit board. As shown, device 66 is a communications system (e.g., used in satellites, high-speed routers and servers, spacecraft, cellular telephones, cellular base stations, etc.). Device 66 can also be another device used in high frequency applications, such as an electrical amplifier and / or radar system.

[0055] B. Polymer aerogel layer material The polymer aerogel layer can comprise organic materials, inorganic materials, or mixtures thereof. Organic aerogels can be made from polyacrylates, polystyrenes, polyacrylonitriles, polyurethanes, polyureas, polyimides, polyamides, polyaramids, polyfurfural alcohol, phenol furfuryl alcohol, melamine formaldehyde, resorcinol formaldehyde, cresol formaldehyde, phenol formaldehyde, polyvinyl alcohol dialdehyde, polycyanurates, polyacrylamides, various epoxies, agar, agarose, and the like. In certain embodiments, the aerogel is a polyimide aerogel.

[0056] Polyimides are a type of polymer with many desirable properties. Polyimide polymers contain nitrogen atoms in the polymer backbone, linked to two carbonyl carbons, somewhat stabilized by adjacent carbonyl groups. The carbonyl groups contain a carbon, called the carbonyl carbon, which is double-bonded to an oxygen atom. Because two different types of monomers are typically used to produce polyimide polymers, polyimides are typically considered AA-BB polymers. Polyimides can also be prepared from AB-type monomers. For example, aminodicarboxylic acid monomers can be polymerized to form AB-type polyimides. Monoamines and / or monoanhydrides can be used as end-capping agents, if desired.

[0057] One class of polyimide monomers is typically diamines, or diamine monomers. It should be understood that diamine monomers can also be diisocyanates, and that isocyanates can be substituted for amines in this description, where appropriate. As known to those skilled in the art, there are other types of monomers that can be used in place of diamine monomers. These other types of monomers are called acid monomers, and are usually in the form of dianhydrides. In this description, the term "diacid monomer" is defined to include dianhydrides, tetraesters, diester acids, tetracarboxylic acids, or trimethylsilyl esters, all of which can react with diamines to produce polyimide polymers. Dianhydrides should be understood to mean tetraesters, diester acids, tetracarboxylic acids, or trimethylsilyl esters, which can be substituted where appropriate. As known to those skilled in the art, there are other types of monomers that can be used in place of diacid monomers.

[0058] Because a diacid monomer has two anhydride groups, a different diamino monomer can react with each anhydride group, and thus the diacid monomer can be located between two different diamino monomers. The diamine monomer contains two amine functional groups; therefore, after the first amine functional group is linked to one diacid monomer, the second amine functional group is available to link to yet another diacid monomer, which then links to another diamine monomer, and so on. In this way, a polymer backbone is formed. The resulting polycondensation reaction product forms a polyamic acid.

[0059] Polyimide polymers are typically formed from two different types of monomers, and different variations of each type of monomer can be mixed. Thus, one, two, or more diacid monomers can be included in the reaction vessel, as well as one, two, or more diamino monomers. If long polymer chains are desired, the total molar amount of diacid monomers is kept approximately the same as the total molar amount of diamino monomers. Because multiple types of diamines or diacids can be used, the various monomer compositions of each polymer chain can be varied to produce polyimides with different properties. For example, a single diamine monomer AA can be reacted with two diacid comonomers B1B1 and B2B2 to form a polyimide having the general formula (AA-B1B1): x -(AA-B2B2) y where x and y are determined by the relative incorporation of B1B1 and B2B2 into the polymer backbone. Alternatively, diamine comonomers A1A1 and A2A2 can be reacted with a single diacid monomer BB to form a polymer chain of the general formula (A1A1-BB): x -(A2A2-BB) y In addition, two diamine comonomers A1A1 and A2A2 can be reacted with two diacid comonomers B1B1 and B2B2 to form polymer chains of the general formula (A1A1-B1B1): w -(A1A1-B2B2) x -(A2A2-B1B1) y -(A2A2-B2B2) z where w, x, y, and z are determined by the relative incorporation of A1A1-B1B1, A1A1-B2B2, A2A2-B1B1, and A2A2-B2B2 into the polymer backbone. More than two diacid comonomers and / or more than two diamine comonomers can also be used. Thus, one or more diamine monomers can be polymerized with one or more diacids, and the general formula of the polymer is determined by varying the amount and type of monomers used.

[0060] There are many examples of monomers that can be used to make polymer aerogels, including polyamic acid amide polymers. In some embodiments, the diamine monomer is a substituted or unsubstituted aromatic diamine, a substituted or unsubstituted alkyl diamine, or a diamine that can contain both aromatic and alkyl functional groups. A non-limiting list of possible diamine monomers includes 4,4'-oxydianiline (ODA), 3,4'-oxydianiline, 3,3'-oxydianiline, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, diaminobenzanilide, 3,5-diaminobenzoic acid, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 1,3-bis-(4-aminophenoxy)benzene, 1,3-bis-(3-aminophenoxy)benzene, 1,4-bis-(4-aminophenoxy)benzene, 1,4-bis-(3-aminophenoxy)benzene, 2,2-bis[4-( 4-aminophenoxy)phenyl]-hexafluoropropane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 4,4'-isopropylidenedianiline, 1-(4-aminophenoxy)-3-(3-aminophenoxy)benzene, 1-(4-aminophenoxy)-4-(3-aminophenoxy)benzene, bis-[4-(4-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(3-aminophenoxy)phenyl]sulfone, bis(4-[4-aminophenoxy]phenyl)ether, 2,2'-bis-(4-aminophenyl)-hexafluoropropane (6F-diamine), 2,2'-bis-(4-phenoxyaniline)isopropylidene, meta-phenylenediamine, para-phenylenediamine, 1,2-diaminobenzene, 4,4'-diaminodiphenylmethane, 2,2-bis(4-aminophenyl)propane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 2,6-diaminopyridine, bis(3-aminophenyl)diethylsilane, 4,4'-diaminodiphenyldiethylsilane, benzidine, dichlorobenzidine, 3,3'-dimethoxybenzidine, 4,4'-Diaminobenzophenone, N,N-bis(4-aminophenyl)-n-butylamine, N,N-bis(4-aminophenyl)methylamine, 1,5-diaminonaphthalene, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4-aminophenyl-3-aminobenzoate, N,N-bis(4-aminophenyl)aniline, bis(p-beta-amino-t-butylphenyl)ether, p-bis-2-(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,3-bis(4-aminophenoxy)benzene, m-xylenediamine, p-xylenediamine, 4,4'-diaminodiphenyl ether phosphine oxide, 4,4'-diaminodiphenyl N-methylamine, 4,4'- Diaminodiphenyl N-phenylamine, amino-terminated polydimethylsiloxane, amino-terminated polypropylene oxide, amino-terminated polybutylene oxide, 4,4'-methylenebis(2-methylcyclohexylamine), 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, and 4,4'-methylenebisbenzenamine, 2,2'-dimethylbenzidine, (also known as 4,4'-diamino-2,2'-dimethylbiphenyl (DMB)), bisaniline-p-xylidene, 4,4'-bis(4-aminophenoxy)biphenyl, 3,3'-bis(4 In certain embodiments, the diamine monomer is ODA, 2,2'-dimethylbenzidine, or both.

[0061] A non-limiting list of possible dianhydride ("diacid") monomers includes hydroquinone dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)bis(phthalic anhydride), 2,2-bis(3, 4-dicarboxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, bis(3,4-dicarboxyphenyl)sulfoxide dianhydride, polysiloxane-containing dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,3,2',3'-benzophenonetetracarboxylic dianhydride, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, 4, 4'-Oxydiphthalic dianhydride, 3,3',4,4'-biphenylsulfonetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)sulfide dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane, 2,6-dichloronaphthalene-1,4 ,5,8-tetracarboxylic dianhydride, 2,7-dichloronapthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, phenanthrene, 8,9,10-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, and thiophene-2,3,4,5-tetracarboxylic dianhydride. In certain embodiments, the dianhydride monomer is BPDA, PMDA, or both.

[0062] In some aspects, the molar ratio of anhydride to total diamine is 0.4:1 to 1.6:1, 0.5:1 to 1.5:1, 0.6:1 to 1.4:1, 0.7:1 to 1.3:1, or particularly 0.8:1 to 1.2:1. In further aspects, the molar ratio of dianhydride to polyfunctional amine (e.g., triamine) is 2:1 to 140:1, 3:1 to 130:1, 4:1 to 120:1, 5:1 to 110:1, 6:1 to 100:1, 7:1 to 90:1, or particularly 8:1 to 80:1. Monoanhydride groups can also be used. Non-limiting examples of monoanhydride groups include 4-amino-1,8-naphthalic anhydride, endo-bicyclo[2.2.2]oct-5-ene-2,3-dicarboxylic anhydride, citraconic anhydride, trans-1,2-cyclohexanedicarboxylic anhydride, 3,6-dichlorophthalic anhydride, 4,5-dichlorophthalic anhydride, tetrachlorophthalic anhydride, 3,6-difluorophthalic anhydride, 4,5-difluorophthalic anhydride, tetrafluorophthalic anhydride, maleic anhydride, 1-cyclopentene-1,2-dicarboxylic anhydride, and 2,2-dimethylglutaric anhydride. Examples of suitable anhydrides include 3,3-dimethylglutaric anhydride, 2,3-dimethylmaleic anhydride, 2,2-dimethylsuccinic anhydride, 2,3-diphenylmaleic anhydride, phthalic anhydride, 3-methylglutaric anhydride, methylsuccinic anhydride, 3-nitrophthalic anhydride, 4-nitrophthalic anhydride, 2,3-pyrazinedicarboxylic anhydride, and 3,4-pyridinedicarboxylic anhydride. In particular, the monoanhydride group may be phthalic anhydride.

[0063] In another embodiment, the polymer composition used to prepare the polymeric aerogel layer includes a polyfunctional amine monomer having at least three primary amine functional groups. The polyfunctional amine may be a substituted or unsubstituted aliphatic polyfunctional amine, a substituted or unsubstituted aromatic polyfunctional amine, or a polyfunctional amine containing a combination of an aliphatic and two aromatic groups, or a combination of an aromatic and two aliphatic groups.A non-limiting list of possible polyfunctional amines includes propane-1,2,3-triamine, 2-aminomethylpropane-1,3-diamine, 3-(2-aminoethyl)pentane-1,5-diamine, bis(hexamethylene)triamine, N',N'-bis(2-aminoethyl)ethane-1,2-diamine, N',N'-bis(3-aminopropyl)propane-1,3-diamine, 4-(3-aminopropyl)heptane-1,7-diamine, N',N'-bis(6-aminopropyl)heptane-1,7-diamine, N',N'-bis(6-aminopropyl)ethane-1,2-diamine, N',N'-bis(2-aminoethyl)ethane-1,2-diamine, N',N'-bis(3-aminopropyl)propane-1,3-diamine, 4-(3-aminopropyl)heptane-1,7-diamine, N',N'-bis(6-aminopropyl)ethane-1,2 ... (aminohexyl)hexane-1,6-diamine, benzene-1,3,5-triamine, cyclohexane-1,3,5-triamine, melamine, N-2-dimethyl-1,2,3-propanetriamine, diethylenetriamine, 1-methyl or 1-ethyl or 1-propyl or 1-benzyl-substituted diethylenetriamines, 1,2-dibenzyldiethylenetriamine, lauryldiethylenetriamine, N-(2-hydroxypropyl)diethylenetriamine , N,N-bis(l-methylheptyl)-N-2-dimethyl-1,2,3-propanetriamine, 2,4,6-tris(4-(4-aminophenoxy)phenyl)pyridine, N,N-dibutyl-N-2-dimethyl-1,2,3-propanetriamine, 4,4'-(2-(4-aminobenzyl)propane-1,3-diyl)dianiline, 4-((bis(4-aminobenzyl)amino)methyl)aniline, 4-(2-(bis(4-aminophenethyl)amino)ethyl)aniline Examples of suitable aromatic polyfunctional amines include 1,3,5-tris(4-aminophenoxy)benzene (TAPOB), 4,4',4"-methanetriyltrianiline, N,N,N',N'-tetrakis(4-aminophenyl)-1,4-phenylenediamine, polyoxypropylene triamine, octa(aminophenyl) polyhedral oligomeric silsesquioxane, or a combination thereof. A specific example of a polyoxypropylene triamine is JEFFAMINE® T-403 from Huntsman Corporation, The Woodlands, TX USA. In certain embodiments, the aromatic polyfunctional amine may be 1,3,5-tris(4-aminophenoxy)benzene or 4,4',4"-methanetriyltrianiline.In some embodiments, the polyfunctional amine comprises three primary amine groups and one or more secondary and / or tertiary amine groups, for example, N',N'-bis(4-aminophenyl)benzene-1,4-diamine.

[0064] Non-limiting examples of capping agents or groups include amine, maleimide, nadimide, acetylene, biphenylene, norbornene, cycloalkyl, and N-propargyl, and those derived from reagents including 5-norbornene-2,3-dicarboxylic anhydride (nadic anhydride, NA), methylnadic anhydride, hexachloronadic anhydride, cis-4-cyclohexene-1,2-dicarboxylic anhydride, 4-amino-N-propargylphthalimide, 4-ethynylphthalic anhydride, and maleic anhydride, among others.

[0065] The characteristics or properties of the final polymer are greatly influenced by the choice of monomers used to produce the polymer. Factors to consider when selecting monomers include the properties of the final polymer, such as flexibility, thermal stability, coefficient of thermal expansion (CTE), coefficient of hydraulic expansion (CHE), and any other properties that are particularly desirable, as well as cost. In many cases, certain important properties of a polymer for a particular application can be identified. Other properties of the polymer may be less important or may have a wide range of acceptable values; therefore, many different monomer combinations may be used.

[0066] In some examples, the polymer backbone may contain additional substituents. The substituents (e.g., oligomers, functional groups, etc.) may be directly attached to the backbone or may be linked to the backbone through a linking group (e.g., a tether or a flexible tether). In other embodiments, compounds or particles may be incorporated (e.g., mixed and / or encapsulated) into the polyimide structure without being covalently bonded to the polyimide structure. In some examples, the incorporation of compounds or particles may be carried out during the polyamic acid reaction process. In some examples, the particles may aggregate, thereby producing polyimides having domains containing different concentrations of non-covalently bound compounds or particles.

[0067] Specific properties of polyimides can be influenced by incorporating certain compounds into the polyimide. Monomer selection is one way to influence specific properties. Another way to influence properties is by adding compounds or property-modifying moieties to the polyimide.

[0068] C. Preparation of polymer aerogel layers Polymer aerogel films that may be used in at least some of the laminates of the present invention are commercially available. Non-limiting examples of such films include Blueshift AeroZero® rolled film (available from Blueshift Materials, Inc. (Spencer, Massachusetts)) and Airloy® film (available from Aerogel Technologies, LLC), with Blueshift AeroZero® rolled film being preferred in some aspects.

[0069] Additionally, and in addition to the processes described below, polymer aerogels (such as films, stock shapes, or monoliths) can be made using methods described in WO 2014 / 189560 to Rodman et al., WO 2017 / 07888 to Sakaguchi et al., WO 2018 / 078512 to Yang et al., WO 2018 / 140804 to Sakaguchi et al., and WO 2019 / 006184 to Irvin et al., WO 2019 / 029191 to Ejaz et al., WO 2017 / 0121483 to Poe et al., and / or U.S. Pat. No. 9,963,571 to Sakaguchi et al., all of which are incorporated by reference in their entireties.

[0070] The following provides non-limiting steps that can be used to make layers of polymeric aerogel suitable for use in the laminates of the present invention. These steps can include: (1) preparation of the polymer gel, (2) optional solvent exchange, (3) drying the polymer solution to form the aerogel, and (4) bonding the polymeric aerogel film onto a substrate.

[0071] 1. Polymer gel formation The first stage in the synthesis of an aerogel can be the synthesis of a polymerized gel. For example, if a polyimide aerogel is desired, at least one acid monomer can be reacted with at least one diamino monomer in a reaction solvent to produce a polyamic acid. As previously mentioned, many acid monomers and diamino monomers can be used to synthesize a polyamic acid. In one aspect, the polyamic acid is contacted with an imidization catalyst in the presence of a chemical dehydrating agent to produce a polymerized polyimide gel via an imidization reaction. "Imidization" is defined as the conversion of a polyimide precursor to an imide. Any imidization catalyst suitable for driving the conversion of a polyimide precursor to a polyimide state is suitable. Non-limiting examples of chemical imidization catalysts include pyridine, methylpyridine, quinoline, isoquinoline, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), triethylenediamine, lutidine, N-methylmorpholine, triethylamine, tripropylamine, tributylamine, other trialkylamines, 2-methylimidazole, 2-ethyl-4-methylimidazole, imidazole, other imidazoles, and combinations thereof. Any dehydrating agent suitable for use in forming imide rings from amic acid precursors is suitable for use in the method of the present invention. Preferred dehydrating agents include at least one compound selected from the group consisting of acetic anhydride, propionic anhydride, n-butyric anhydride, benzoic anhydride, trifluoroacetic anhydride, phosphorus trichloride, and dicyclohexylcarbodiimide.

[0072] In one aspect of the present invention, one or more diamino monomers and one or more polyfunctional amine monomers are premixed in one or more solvents, followed by the addition of one or more dianhydrides (e.g., diacid monomers) in small, sequential additions at predetermined time increments while monitoring the viscosity. The desired viscosity of the polymerization solution can range from 50 to 20,000 cP, or more specifically, from 500 to 5,000 cP. Non-crosslinked aerogels can be prepared by carrying out the reaction using incremental additions of dianhydrides while monitoring the viscosity. For example, a triamine monomer (23 equivalents) can be added to a solvent to obtain a 0.0081 molar solution. A first diamine monomer (280 equivalents) can be added to the solution, followed by a second diamine monomer (280 equivalents). Next, dianhydrides (552 equivalents total) can be added in small, sequential additions at predetermined time increments while monitoring the viscosity. The dianhydrides can be added until the viscosity reaches 1,000 to 1,500 cP. For example, a first portion of the dianhydride can be added, the reaction can be stirred (e.g., 20 minutes), a second portion of the dianhydride can be added, and then a sample of the reaction mixture can be analyzed for viscosity. After stirring for an additional time (e.g., 20 minutes), a third portion of the dianhydride can be added, and a sample can be taken for viscosity analysis. After further stirring for a desired period of time (e.g., 10-12 hours), the monoanhydride (96 equivalents) can be added. After reaching the target viscosity, the reaction mixture can be stirred for a desired period of time (e.g., 10-12 hours) or until the reaction is deemed complete.

[0073] The reaction temperature for gel formation can be determined by routine experimentation depending on the starting materials. In preferred embodiments, the temperature can be equal to or greater than any one of 15°C, 20°C, 30°C, 35°C, 40°C, and 45°C, or between any two of these values. After a desired time (e.g., about 2 hours), the product can be isolated (e.g., filtered), followed by the addition of a nitrogen-containing hydrocarbon (828 equivalents) and a dehydrating agent (1214 equivalents). The addition of the nitrogen-containing hydrocarbon and / or dehydrating agent can be carried out at any temperature. In some embodiments, the nitrogen-containing hydrocarbon and / or dehydrating agent is added to the solution at 20°C to 28°C (e.g., room temperature) and stirred at that temperature for the desired time. In some examples, after the addition of the nitrogen-containing hydrocarbon and / or dehydrating agent, the solution temperature is raised to 150°C.

[0074] Reaction solvents may include dimethyl sulfoxide (DMSO), diethyl sulfoxide, N,N-dimethylformamide (DMF), N,N-diethylformamide, N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 1-methyl-2-pyrrolidinone, N-cyclohexyl-2-pyrrolidone, 1,13-dimethyl-2-imidazolidinone, diethylene glycol dimethoxy ether, o-dichlorobenzene, phenol, cresol, xylenol, catechol, butyrolactone, hexamethylphosphoramide, and mixtures thereof. The reaction solvent and other reactants can be selected based on their compatibility with the applied materials and methods; that is, whether the polymerized polyamic acid amide gel is cast onto a support film, injected into a moldable part, or poured into a shape for further processing into a workpiece. In certain embodiments, the reaction solvent is DMSO.

[0075] With the above in mind, the incorporation of macropores into the aerogel polymer matrix, as well as the amount of such macropores present, can be accomplished in the manner outlined. In one non-limiting manner, the formation of macropores, as opposed to small mesopores and micropores, can be controlled primarily by controlling the polymer / solvent dynamics during gel formation. This allows for control of the pore structure and the amount and volume of macroporous, mesoporous, and microporous cells. For example, a curing additive that reduces the solubility of the resulting polymer during polymerization, such as 1,4-diazabicyclo[2.2.2]octane, can produce a polymer gel containing more macropores than another curing additive that improves the solubility of the resulting polymer, such as trimethylamine. In another specific non-limiting example, when producing polyimide aerogels, the ratio of rigid amines (e.g., p-phenylenediamine (p-PDA)) incorporated into the polymer backbone to more flexible diamines (e.g., -ODA) can be increased to favor the formation of macropores over small mesopores and micropores.

[0076] The polymer solution may be cast onto a cast sheet covered with a support film for a certain period of time. Casting may include spin casting, gravure coating, three-roll coating, roll-type knife coating, slot-die extrusion, dip coating, Mayer rod coating, or other techniques. In one embodiment, the cast sheet is a polyethylene terephthalate (PET) cast sheet. After the time period, the polymerized reinforced gel is removed from the cast sheet and prepared for the solvent exchange process. In some embodiments, the cast film may be heated to elevated temperatures in stages to remove the solvent and convert the amic acid functional groups in the polyamic acid to polyimide via a dehydration cycloreaction, also known as imidization. In some examples, polyamic acid may be converted to polyimide in solution by the addition of a chemical dehydrating agent, a catalyst, and / or heat.

[0077] In some embodiments, polyimide polymers can be produced by preparing a polyamic acid polymer in a reaction vessel, then forming the polyamic acid into a sheet or film, followed by treatment with a catalyst or heat and a catalyst to convert the polyamic acid into a polyimide.

[0078] The wet gel used to prepare the aerogel may be prepared by any known gel-forming technique, for example, by adjusting the pH and / or temperature of a dilute metal oxide solution to the point where gelation occurs.

[0079] 2. Optional Solvent Exchange After synthesizing the polymer gel, in certain instances, it may be desirable to perform a solvent exchange, in which the reaction solvent is replaced with a more desirable second solvent. Thus, in one embodiment, a solvent exchange can be performed by placing the polymer gel inside a pressure vessel and immersing it in a mixture containing the reaction solvent and the second solvent. A high-pressure atmosphere is then created inside the pressure vessel, thereby forcing the second solvent into the polymer gel and displacing a portion of the reaction solvent. Alternatively, the solvent exchange step may be performed without using a high-pressure environment. Multiple solvent exchanges may be necessary. In some embodiments, solvent exchange is not required.

[0080] The time required to perform a solvent exchange will vary depending on the type of polymer undergoing the exchange and the reaction solvent and second solvent used. In one embodiment, each solvent exchange can take 1 to 168 hours, or any period therebetween, including 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, or 23, 24, 25, 50, 75, 100, 125, 150, 155, 160, 165, 166, 167, or 168 hours. In another embodiment, each solvent exchange can take approximately 1 to 60 minutes, or about 30 minutes. Exemplary second solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, tert-butanol, 3-methyl-2-butanol, 3,3-dimethyl-2-butanol, 2-pentanol, 3-pentanol, 2,2-dimethylpropan-1-ol, cyclohexanol, diethylene glycol, cyclohexanone, acetone, acetylacetone, 1,4-dioxane, diethyl ether, dichloromethane, trichloroethylene, chloroform, carbon tetrachloride, water, and mixtures thereof. In certain non-limiting embodiments, the second solvent can have a freezing point suitable for carrying out a supercritical or subcritical drying step. For example, at 1 atmosphere, tert-butyl alcohol has a freezing point of 25.5°C, and water has a freezing point of 0°C. Alternatively, as described below, drying can be carried out without a supercritical or subcritical drying step, such as by evaporative drying techniques.

[0081] The temperature and pressure used in the solvent exchange step may be varied. The duration of the solvent exchange step can be adjusted by conducting the solvent exchange at various temperatures or atmospheric pressures, or both, provided that the pressure and temperature within the pressure vessel do not cause either the first solvent or the second solvent to leave the liquid phase and become a gas, vapor, solid, or supercritical fluid. Generally, higher pressures and / or temperatures decrease the amount of time required to conduct the solvent exchange, and lower temperatures and / or pressures increase the amount of time required to conduct the solvent exchange.

[0082] 3. Cooling and drying In one embodiment, after solvent exchange, the polymerized gel can be exposed to supercritical drying. In this example, the solvent in the gel can be removed by supercritical CO2 extraction.

[0083] In another embodiment, after solvent exchange, the polymerized gel can be subjected to subcritical drying. In this example, the gel can be cooled below the freezing point of the second solvent and subjected to a freeze-drying or lyophilization process to produce an aerogel. For example, if the second solvent is water, the polymerized gel can be cooled to below 0°C. After cooling, the polymerized gel can be subjected to a vacuum for a period of time to sublimate the second solvent.

[0084] In yet another embodiment, after solvent exchange, the polymerized gel can be subjected to subcritical drying, optionally with heating, after most of the second solvent has been removed by sublimation. In this example, the partially dried gel material is heated to a temperature near or above the boiling point of the second solvent for a period of time. The period can range from several hours to several days, with a typical period being about 4 hours. During the sublimation step, a portion of the second solvent present in the polymerized gel is removed, leaving behind a gel that may have macropores, mesopores, or micropores, or any combination thereof, or all of such pore sizes. After the sublimation step is complete, or nearly complete, the aerogel is formed.

[0085] In yet another embodiment, after solvent exchange, the polymerized gel can be dried under ambient conditions, for example, by removing the solvent under a flow of gas (e.g., air, anhydrous gas, inert gas (e.g., nitrogen (N) gas), etc.). Additionally, passive drying techniques can be used, such as simply exposing the gel to ambient conditions without an airflow.

[0086] Once cooled or dried, the films and stock shapes can be configured for use in the laminates of the present invention. For example, the film or stock shape can be machined (e.g., by cutting or grinding) into a desired shape, such as a square, rectangle, circle, triangle, irregular, random, etc. Also, as previously described, the film or stock shape can be attached to a support material, such as with an adhesive. In an alternative embodiment, the support material can be incorporated into the matrix of a polymer aerogel, as described below.

[0087] 4. Incorporation of a reinforcing layer into a polymer aerogel matrix In addition to the methods described above regarding the use of adhesives to bond polymer aerogels to support materials, any embodiment of the present invention can include incorporating a support material into the polymer matrix to create reinforced polymer aerogels without the use of adhesives. Of note, during the production of unreinforced polymer aerogels, a reinforcing support film can be used as a carrier to support the gelled film during processing. During unwinding, the gelled film can be irreversibly pressed into the carrier film. Pressing the gelled film into the carrier film can provide substantial durability improvements. In another example, the polymer solution can be cast into a reinforcing or support material during the aforementioned solution casting step.

[0088] Substrate selection and direct casting can allow for optimization (e.g., minimization) of the thickness of the resulting reinforced aerogel material. This process can also be extended to the production of fiber-reinforced polymer aerogels, with internally reinforced polyimide aerogels provided as an example. The process can include: (a) forming a polyamic acid solution from a mixture of dianhydride and diamine monomers in a polar solvent such as DMSO, DMAc, NMP, or DMF; (b) contacting the polyamic acid solution with the chemical curing and dehydrating agents listed above to initiate chemical imidization; (c) casting the polyamic acid solution onto a fiber support and allowing it to infiltrate before gelation; (d) allowing the catalytic polyamic acid solution to gel around and within the fiber support during chemical imidization; (e) optionally, performing a solvent exchange to facilitate drying; and (f) removing the transient liquid phase contained within the gel by supercritical, subcritical, or ambient drying to obtain an internally reinforced aerogel. [Example]

[0089] The present invention will be described in detail by way of specific examples. The following examples are provided for illustrative purposes only and are not intended to limit the present invention in any way. Those skilled in the art will readily recognize non-critical parameters that can be changed or modified to achieve essentially the same results.

[0090] Table 1 shows the acronyms of the compounds used in the following examples.

[0091] [Table 1]

[0092] The structure of the starting material is shown below. TIFF0007810658000002.tif41158

[0093] Example 1 (Preparation of hyperbranched BPDA / DMB-ODA polyimide) A reactor equipped with a stirrer and water jacket was used. The temperature was maintained between 18 and 35°C by adjusting the water flow rate through the reactor jacket. DMSO (108.2 lbs., 49.1 kg) was added to the reactor, and the stirrer speed was adjusted to 120-135 rpm. TAPOB (65.13 g) was added to the solvent. To this solution, DMB (1081.6 g) was added, followed by ODA (1020.2 g). The first portion of BPDA (1438.4 g) was then added. After stirring for 20 minutes, the viscosity of a sample of the reaction mixture was analyzed using a Brookfield DV1 viscometer (Brookfield, AMETEK, USA). The second portion of BPDA (1407.8 g) was added, and the reaction mixture was stirred for an additional 20 minutes. The third portion of BPDA (138.62 g) was added, and the reaction mixture was stirred for 20 minutes. The viscosity of a sample of the reaction mixture was analyzed. After stirring for 8 hours, PA (86.03 g) was added. The resulting reaction mixture was stirred until no more solids were visible. After 2 hours, the product was removed from the reaction vessel, filtered, and weighed.

[0094] Example 2 (Preparation of hyperbranched polyimide aerogel monoliths by freeze-drying) The resin prepared in Example 1 (approximately 10,000 g) was mixed with triethylamine (approximately 219 g) and acetic anhydride (approximately 561 g) for 5 minutes. After mixing, the resulting solution was poured into a square 15" x 15" mold and allowed to sit for 48 hours. The gelled shapes were removed from the mold and placed in an acetone bath. After 24 hours of soaking, the acetone bath was replaced with fresh acetone. The soaking and exchanging process was repeated five times. After the final exchange, the bath was replaced with tertiary butyl alcohol. After 24 hours of soaking, the tertiary butyl alcohol bath was replaced with fresh tertiary butyl alcohol. The soaking and exchanging process was repeated three times. The parts were then flash frozen and subjected to subcritical drying at 5°C for 96 hours, followed by drying under vacuum at 50°C for 48 hours. The final recovered aerogel portion had an open cell structure as observed by scanning electron microscopy (SEM) performed on a Phenom Pro Scanning Electron Microscope (Phenom-World, the Netherlands), and a Penetrometer of 0.22 g / cm as measured according to ASTM D4404-10 with a Micromeritics® AutoPore V 9605 Automatic Mercury Penetrometer (Micromeritics® Instrument Corporation, USA). 3 The aerogel exhibited a density of 1.0 μm and a porosity of 88.5%, a compressive modulus of 2.2 MPa as determined by American Standard Test Method (ASTM) D395-16, and a compressive strength at 25% strain of 3.5 MPa as determined by ASTM D395-16. The pore size distribution was measured according to ASTM D4404-10 using a Micromeritics® AutoPore V 9605 Automatic Mercury Penetrometer (Micromeritics® Instrument Corporation, USA), and the pore diameter distribution is shown in Figure 7. From the data, it was determined that 100% of the pores were macropores, with an average pore diameter of approximately 1,200 nm, thus confirming that a macroporous aerogel structure had been produced.

[0095] Example 3 (Preparation of hyperbranched polyimide aerogel monoliths by thermal drying) The resin (approximately 10,000 g) prepared in Example 1 was mixed with triethylamine (approximately 219 g) and acetic anhydride (approximately 561 g) at temperatures ranging from 10 to 35°C for 5 minutes. After mixing, the resulting solution was poured into a square 15" x 15" mold and allowed to sit for 48 hours. The gelled shapes were removed from the mold and placed in an acetone bath. After 24 hours of soaking, the acetone bath was replaced with fresh acetone. The soaking and exchange process was repeated five times. After the final exchange, the parts were dried in an ambient (approximately 20 to 30°C) drying process to evaporate most of the acetone over 48 hours, followed by thermal drying at 50°C for 4 hours, 100°C for 2 hours, 150°C for 1 hour, and then 200°C for 30 minutes. The final recovered aerogel had properties similar to those observed in Example 2.

[0096] Example 4 (Preparation of hyperbranched polyimides) As described in Example 1, TAPOB (approximately 2.86 g) was added to a reaction vessel containing approximately 2,523.54 g of DMSO at a temperature of 18-35°C. To this solution, the first portion of DMB (approximately 46.75 g) was added, followed by the first portion of ODA (approximately 44.09 g). After stirring for approximately 20 minutes, the first portion of BPDA (approximately 119.46 g) was added. After stirring for approximately 20 minutes, TAPOB (approximately 2.86 g), DMB (approximately 46.75 g), and ODA (approximately 44.09 g) were added. After stirring for approximately 20 minutes, BPDA (approximately 119.46 g) was added. After stirring for approximately 20 minutes, TAPOB (approximately 2.86 g), DMB (approximately 46.75 g), and ODA (approximately 44.09 g) were added. After stirring for approximately 20 minutes, BPDA (approximately 119.46 g) was added. After stirring for about 8 hours, PA (about 50.12 g) was added. The resulting reaction mixture was stirred until no more solids were visible. After about 2 hours, the product was removed from the reaction vessel, filtered, and weighed.

[0097] Example 5 (Preparation of hyperbranched polyimide aerogel monoliths by freeze-drying) The resin prepared in Example 4 (approximately 400 g) was mixed with 2-methylimidazole (approximately 53.34 g) at temperatures between 18 and 35°C for 5 minutes, and then mixed with benzoic anhydride (approximately 161.67 g) for 5 minutes. After mixing, the resulting solution was poured into a square 3" x 3" mold and placed in a 75°C oven for 30 minutes, then left at room temperature overnight. The gelled shapes were removed from the mold and placed in an acetone bath. After 24 hours of soaking, the acetone bath was replaced with fresh acetone. The soaking and exchanging process was repeated five times. After the final exchange, the bath was replaced with tertiary butyl alcohol. After 24 hours of soaking, the tertiary butyl alcohol bath was replaced with fresh tertiary butyl alcohol. The soaking and exchanging process was repeated three times. The parts were then frozen in a shelf freezer and subjected to subcritical drying at 5°C for 96 hours, followed by drying under vacuum at 50°C for 48 hours. The final recovered aerogel portion had an open cell structure as observed by scanning electron microscopy (SEM) performed on a Phenom Pro Scanning Electron Microscope (Phenom-World, the Netherlands), and a Penetrometer density of 0.15 g / cm as measured according to ASTM D4404-10 with a Micromeritics® AutoPore V 9605 Automatic Mercury Penetrometer (Micromeritics® Instrument Corporation, USA). 3 The aerogel exhibited a density of 0.01 and a porosity of 92.2%. The pore size distribution was measured according to ASTM D4404-10 using a Micromeritics® AutoPore V 9605 Automatic Mercury Penetrometer (Micromeritics® Instrument Corporation, USA), and is shown in Figure 8. From the data, it was determined that 96.3% of the pore volume of the cast aerogel was occupied by pores with an average pore diameter greater than 50 nm, thus forming an aerogel with a macroporous structure.

[0098] Example 6 (Preparation of hyperbranched polyimides) As described in Example 1, TAPOB (approximately 2.05 g) was added to a reaction vessel containing approximately 2,776.57 g of DMSO at a temperature of 18-35°C. To this solution, the first portion of DMB (approximately 33.54 g) was added, followed by the first portion of ODA (approximately 31.63 g). After stirring for approximately 20 minutes, the first portion of PMDA (approximately 67.04 g) was added. After stirring for approximately 20 minutes, TAPOB (approximately 2.05 g), DMB (approximately 33.54 g), and ODA (approximately 31.63 g) were added. After stirring for approximately 20 minutes, PMDA (approximately 67.04 g) was added. After stirring for approximately 20 minutes, TAPOB (approximately 2.05 g), DMB (approximately 33.54 g), and ODA (approximately 31.63 g) were added. After stirring for approximately 20 minutes, PMDA (approximately 67.04 g) was added. After stirring for about 8 hours, PA (about 18.12 g) was added. The resulting reaction mixture was stirred until no more solids were visible. After about 2 hours, the product was removed from the reaction vessel, filtered, and weighed.

[0099] Example 7 (Preparation of hyperbranched polyimide aerogel monoliths by freeze-drying) The resin prepared in Example 6 (approximately 400 g) was mixed with 2-methylimidazole (approximately 40.38 g) for 5 minutes at temperatures between 18 and 35°C, and then mixed with benzoic anhydride (approximately 122.38 g) for 5 minutes. After mixing, the resulting solution was poured into a square 3" x 3" mold and placed in a 75°C oven for 30 minutes, then left at room temperature overnight. The gelled shapes were removed from the mold and placed in an acetone bath. After 24 hours of soaking, the acetone bath was replaced with fresh acetone. The soaking and exchanging process was repeated five times. After the final exchange, the bath was replaced with tertiary butyl alcohol. After 24 hours of soaking, the tertiary butyl alcohol bath was replaced with fresh tertiary butyl alcohol. The soaking and exchanging process was repeated three times. The parts were then frozen in a shelf freezer and subjected to subcritical drying at 5°C for 96 hours, followed by drying under vacuum at 50°C for 48 hours. The final recovered aerogel portion had an open cell structure as observed by scanning electron microscopy (SEM) performed on a Phenom Pro Scanning Electron Microscope (Phenom-World, the Netherlands), and a Penetrometer of 0.23 g / cm as measured according to ASTM D4404-10 on a Micromeritics® AutoPore V 9605 Automatic Mercury Penetrometer (Micromeritics® Instrument Corporation, USA). 3 The aerogel exhibited a density of 0.01 and a porosity of 82.7%. The pore size distribution was measured according to ASTM D4404-10 using a Micromeritics® AutoPore V 9605 Automatic Mercury Penetrometer (Micromeritics® Instrument Corporation, USA), and the pore diameter distribution is shown in Figure 9. From the data, it was determined that 90.6% of the pore volume of the aerogel was occupied by pores with an average pore diameter greater than 50 nm.

[0100] Example 8 (Preparation of hyperbranched polyamic films) A reactor equipped with a stirrer and water jacket was used. The temperature was maintained between 20 and 28°C by adjusting the water flow rate through the reactor jacket. DMSO (108.2 lbs., 49.1 kg) was added to the reactor, and the stirrer speed was adjusted to 120-135 rpm. TAPOB (65.03 g) was added to the solvent. To this solution, DMB (1,080.96 g) was added, followed by ODA (1,018.73 g). The first portion of BPDA (1,524.71 g) was added. After stirring for 20 minutes, a sample of the reaction mixture was analyzed for viscosity. A second portion of BPDA (1,420.97 g) was added, and the reaction mixture was stirred for an additional 20 minutes. A sample of the reaction mixture was analyzed for viscosity. A third portion of BPDA (42.81 g) was added, and the reaction mixture was stirred for an additional 20 minutes. A sample of the reaction mixture was analyzed for viscosity. After stirring for 8 hours, PA (77.62 g) was added. The resulting reaction mixture was stirred until no more solids were visible. After 2 hours, the resin was removed from the reaction vessel, filtered, and weighed.

[0101] Resin (10,000 g) was mixed with 2-methylimidazole (250 g) for 5 minutes. Benzoic anhydride (945 g) was added, and the solution was mixed for an additional 5 minutes. After mixing, the resulting solution was poured onto a transfer polyester substrate, which was then heated in an oven at 100°C for 30 seconds. The gelled film was collected and placed in an acetone bath. After 24 hours of immersion, the acetone bath was replaced with fresh acetone. The immersion and exchange process was repeated six times. After the final exchange, the gelled film was removed. The acetone solvent was evaporated under airflow at room temperature, followed by drying at 200°C for 2 hours. The final recovered aerogel portion had an open cell structure as observed by scanning electron microscopy (SEM) performed on a Phenom Pro Scanning Electron Microscope (Phenom-World, the Netherlands), and a Penetrometer of 0.20 g / cm as measured according to ASTM D4404-10 on a Micromeritics® AutoPore V 9605 Automatic Mercury Penetrometer (Micromeritics® Instrument Corporation, USA). 3and a porosity of >80%. The final recovered film exhibited a tensile strength and elongation of 1200 psi (8.27 MPa) and 14%, respectively, at room temperature, as measured according to ASTM D882-12. The film had an average pore size of 400 nm.

[0102] Example 9 (Preparation of copper-clad polyimide aerogel laminate) A laminate was prepared with a polyimide aerogel layer bonded between two copper layers by heat laminating adhesive sheets to the aerogel film on either side of the aerogel film. The copper foil layers were each 1.4 mil thick, and the polyimide aerogel layer was 139.7 microns (5.5 mils) thick Blueshift AeroZero® film.

[0103] Prior to lamination, the AeroZero® film was dried in a convection oven at 120°C for 30 minutes. After assembling the aerogel film between two adhesive sheets with copper foil layers on top, the sample was placed in a vacuum press. Copper-clad laminates were fabricated using three low-Dk / Df adhesives: Teflon FEP (Dupont), Pyralux GPL (Dupont), and TSU 510 (ToyoChem).

[0104] The press was heated to 180°C using a temperature ramp of 5°C / min and a pressure increase from 4 psi to 300 psi. The press was then held isothermal at 180°C for a period ranging from 10 to 60 minutes depending on the type of adhesive used. The press was then cooled to 50°C at a temperature ramp of 5°C / min, with the pressure held at 300 psi.

[0105] Example 10 (Dielectric properties of polyimide aerogel film) The dielectric constant (Dk) and loss tangent (Df) properties of Blueshift AeroZero® films at 1 MHz and 1 GHz were measured according to IPC TM-650 Method 2.5.5.9. Parallel Plate Method. Samples were conditioned at 23±5°C and 50±5% RH for a minimum of 24 hours prior to testing. The polyimide aerogel film used had a thickness of 148 microns. Dielectric properties are shown in Table 1.

[0106] [Table 1]

[0107] Example 11 (Dielectric properties of polyimide aerogel films at high frequencies) The dielectric constant (Dk) and loss tangent (Df) of a 157.8 micron thick polyimide aerogel film were measured at 10 GHz using a Damaskos Thin Sheet tester, with the results being Dk = 1.45 and Df = 0.0046.

[0108] Example 12 (Dielectric properties of polyimide aerogel stock shapes) The dielectric constant (Dk) and loss tangent (Df) of 10.2 mm thick polyimide aerogel samples were measured at room temperature (22°C, 22% RH) using a DI Model 08 Thin Sheet Tester and a DI Model 900T Open Resonator with an Anritsu VectorStar vector network analyzer under CAVITY™ control for Macintosh OS X. Thin Sheet Tester measurements conform to ASTM D 2520 Part C. Table 2 shows the average dielectric constant (Dk) and loss tangent (Df) measured in four directions (X1, X2, Y1, and Y2) using the Model 08 Thin Sheet Tester.

[0109] [Table 2]

[0110] Table 3 shows the average dielectric constant (Dk) and loss tangent (Df) measured in two directions (X, Y) using a Model 900T Open Resonator for frequencies ranging from 7.3 GHz to 50 GHz.

[0111] [Table 3]

[0112] Example 13 (Dielectric properties of polyimide aerogel copper-clad laminate) The dielectric constant (Dk) and loss tangent (Df) of an etched sample of a 161 micron thick polyimide aerogel copper-clad laminate of polyimide aerogel film were measured at 10 GHz, with the results being Dk = 2.0 and Df = 0.004.

[0113] The foregoing specification and examples provide a complete description of the structure and use of exemplary embodiments. While certain embodiments have been described above in some detail, or with reference to one or more individual embodiments, those skilled in the art may make numerous modifications to the disclosed embodiments without departing from the scope of the present invention. Therefore, it is not intended that the various exemplary embodiments of the apparatus and method be limited to the particular forms disclosed. Rather, they include all modifications and alternatives that fall within the scope of the claims, and embodiments other than those shown may include some or all of the features of the illustrated embodiments. For example, elements may be omitted or combined in a single structure and / or connections may be substituted. Furthermore, where appropriate, aspects of any of the above-described embodiments may be combined with aspects of any other of the above-described embodiments to form further embodiments having equivalent or different characteristics and / or functionality and addressing the same or different problems. Similarly, it will be understood that the benefits and advantages described above may relate to one embodiment or to several embodiments.

[0114] The claims are not intended to, and should not be construed as including, means-plus or step-plus-function limitations, unless such limitations are expressly recited in a given claim using the words "means" or "step," respectively.

Claims

1. A conductive layer comprising: two or more conductive layers, including a first conductive layer and a second conductive layer, each of the first conductive layer and the second conductive layer comprising at least 90% copper by weight; two or more electrically insulating layers, including a first electrically insulating layer and a second electrically insulating layer, the first electrically insulating layer and the second electrically insulating layer being bonded to the first conductive layer and the second conductive layer, respectively, by one or more adhesive layers; and the first electrically insulating layer and the second electrically insulating layer being bonded by a further adhesive layer, the electrically insulating layers each comprising an organic polymer aerogel. A laminate comprising: at least a portion of the front surface of the stack is defined by a first one of the conductive layers; and At least a portion of the rear surface of the stack is defined by a second one of the conductive layers. Laminate.

2. 10. The laminate of claim 1, wherein at least one of the conductive layers has a thickness of 0.5 mils to 3.0 mils.

3. At least one of the conductive layers must have a thickness of 0.35 to 3.0 oz / ft 2 2. The laminate of claim 1, having an areal density of 0.15 .mu.m.

4. At least one of the conductive layers is 0.5 oz / ft 2 4. The laminate of claim 3, having an areal density of 5. The laminate of claim 1, wherein at least one of the organic polymer aerogels comprises an open cell structure.

6. The laminate of claim 1, wherein at least one of the organic polymer aerogels comprises micropores, mesopores, and / or macropores.

7. At least one of the organic polymer aerogels has a pore volume; and At least 10% of the pore volume is macropores; The laminate according to claim 6.

8. At least one of the organic polymer aerogels has a pore volume; and At least 10% of the pore volume is occupied by micropores and / or mesopores; The laminate according to claim 6.

9. A laminate according to any one of claims 1 to 5, wherein at least one of the organic polymer aerogels has an average pore diameter of 2.0 nm to 50 nm.

10. A laminate according to any one of claims 1 to 5, wherein at least one of the organic polymer aerogels has an average pore diameter of 50 nm to 5,000 nm.

11. 11. The laminate of claim 10, wherein the average pore diameter is from 100 nm to 800 nm.

12. The laminate of claim 1, wherein at least one of the organic polymer aerogels comprises at least 90% by weight of organic polymer.

13. The laminate of claim 1, wherein at least one of the organic polymer aerogels comprises at least 90% by weight of polyimide, polyamide, polyaramid, polyurethane, polyurea, and / or polyester.

14. The laminate of claim 13, wherein at least one of said organic polymer aerogels comprises at least 90% by weight of polyimide.

15. The laminate of claim 1, wherein at least one of the organic polymer aerogels has a thickness of 20 mils or less.

16. The laminate of claim 15, wherein at least one of the organic polymer aerogels has a thickness of 12 mils or less.

17. The laminate of claim 16, wherein at least one of the organic polymer aerogels has a thickness of 7.0 mils or less.

18. The laminate of claim 1, wherein at least one of the organic polymer aerogels has a thickness of 3.0 to 20 mils.

19. The laminate of claim 1, wherein at least one of the organic polymer aerogels has a decomposition temperature of 400°C or greater.

20. 10. The laminate of claim 1, wherein at least one of the adhesive layers comprises a fluoropolymer film.

21. 10. The laminate of claim 1, wherein at least one of the adhesive layers comprises a polyimide film.

22. The laminate of claim 1 , wherein at least one of the adhesive layers comprises a B-stage epoxy.

23. The laminate of claim 1 , wherein at least one of the adhesive layers has a dielectric constant of 3.5 or less at 10 GHz.

24. 10. The laminate of claim 1, wherein at least one of the adhesive layers has a dielectric loss tangent of 0.0040 or less at 10 GHz.

25. The laminate of claim 1, wherein at least one of the adhesive layers has a decomposition temperature of 350°C or greater.

26. The laminate of claim 1, wherein at least one of the adhesive layers has a glass transition temperature or melting point of 100°C or higher.

27. The laminate of claim 1, wherein at least one of the adhesive layers has a thickness of from 0.3 mils to 5 mils.

28. No conductive layer is disposed between adjacent layers of the electrically insulating layers. The laminate of any one of claims 1 to 27.

29. 10. The laminate of claim 1, having a thickness of 5.0 mils to 100 mils.

30. The laminate of claim 1 , arranged in a rolled form such that a portion of the front surface of the laminate faces a portion of the rear surface of the laminate.

31. 10. The laminate of claim 1, having a dielectric constant of 2.0 or less at 10 GHz.

32. 32. The laminate of claim 31, having a dielectric constant of 1.75 or less.

33. 10. The laminate of claim 1, having a dissipation factor of 0.0025 or less at 10 GHz.

34. 34. The laminate of claim 33, having a dissipation factor of 0.002 or less.

35. one or more reinforcing layers; each of the reinforcing layers has a bending stiffness that is at least 10% greater than the bending stiffness of each of the electrically conductive and electrically insulating layers; and / or at least one of the reinforcing layers is at least partially embedded in an organic polymer aerogel such that for at least one of the electrical insulation layers, the Young's modulus of the electrical insulation layer is at least 200 MPa; and / or For at least one of the electrical insulation layers, the plurality of fibers are dispersed in the organic polymer aerogel such that the Young's modulus of the electrical insulation layer is at least 200 MPa. The laminate according to claim 1.

36. At least one of the reinforcing layers is one or more unidirectional, woven, or nonwoven sheets containing fibers, and / or one or more paper sheets; 36. The laminate of claim 35, comprising:

37. 10. The laminate of claim 1, which is fiber-free.

38. At least one of the adhesive layers comprises: containing B-stage epoxy; or 10. The laminate of claim 1, having a dielectric constant of 3.5 or less at 10 GHz, a dissipation factor of 0.0040 or less at 10 GHz, a decomposition temperature of 350°C or greater, and a glass transition temperature or melting point of 100°C or greater.

39. A laminate according to any one of claims 1 to 38; a solder mask layer bonded to at least one of the front and rear surfaces such that the solder mask layer covers at least a majority of the surface, the solder mask layer comprising at least 90% by weight of a polymer; and a circuit board.

40. 40. The circuit board of claim 39, wherein the solder mask layer has a thickness of 3.2 mils or less.

41. 41. An apparatus comprising the circuit board of claim 39 or 40, an antenna electrically coupled to the circuit board; and / or An apparatus that is an electrical amplifier, a radar system, or a communications system.

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