Printed circuit board containing coated boron nitride

Abstract

In one embodiment, the printed circuit board (12) includes a polymer matrix, a reinforcing layer (42), and a plurality of coated boron nitride particles (44), the plurality of coated boron nitride particles including a coating having an average coating thickness of 1 to 100 nanometers. The polymer matrix can include at least one of epoxy, polyphenylene ether, polystyrene, ethylene-propylene dicyclopentadiene copolymer, polybutadiene, polyisoprene, a fluoropolymer, or a crosslinked matrix including at least one of triallyl cyanurate, triallyl isocyanurate, 1,2,4-trivinylcyclohexane, trimethylolpropane triacrylate, or trimethylolpropane trimethacrylate.

Description

[Technical Field]

[0001] [Cross-references to related applications] This application claims the interests of U.S. Provisional Patent Application No. 62 / 740,083, filed on 2 October 2018. The related application is incorporated herein by reference in its entirety. [Background technology]

[0002] Disclosed herein are printed circuit boards and methods for manufacturing printed circuit boards.

[0003] The circuit designs of electronic devices such as televisions, radios, computers, medical equipment, office equipment, and communication equipment are becoming increasingly smaller and thinner. The increased output of these electronic components leads to increased heat generation. Furthermore, the dense packing of smaller electronic components into very small spaces results in more intense heat generation, accompanied by increased hot spot temperatures. Simultaneously, temperature-sensitive elements within electronic devices may need to be maintained within a specified operating temperature to avoid significant performance degradation or even system failure.

[0004] In this context, printed circuit boards (PCBs) have been developed to facilitate effective heat dissipation. Generally, these PCBs are based on composite materials such as thermosetting polymers containing thermally conductive particles. For example, epoxy is one of the most widely used thermosetting polymers in the art due to its excellent adhesive properties and processability. However, epoxy itself has relatively low thermal conductivity and therefore does not effectively dissipate the heat generated in advanced microelectronic devices. As a result, thermally conductive materials such as aluminum nitride (AlN), boron nitride (BN), aluminum oxide (Al2O3), and silicon carbide (SiC) are typically incorporated into the polymer to achieve effective heat dissipation.

[0005] While the addition of such thermally conductive materials has been shown to increase the thermal conductivity of various printed circuit boards, these fillers often experience at least one of the following long-term problems: reduced mechanical properties, decreased peel strength, or thermal aging. It would be particularly advantageous if printed circuit boards could be developed that are easily processable, have improved mechanical / adhesive properties for current thermal interfaces, and can also provide improved heat transfer efficiency. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] U.S. Patent No. 5,898,009 [Patent Document 2] U.S. Patent No. 6,048,511 [Patent Document 3] U.S. Patent Application Publication No. 2005 / 0041373 [Patent Document 4] U.S. Patent No. 6,951,583 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Disclosed herein are printed circuit boards and methods for manufacturing printed circuit boards. [Means for solving the problem]

[0008] In one embodiment, the printed circuit board comprises a polymer matrix, a reinforcing layer, and a plurality of coated boron nitride particles, wherein the plurality of coated boron nitride particles include a coating having an average coating thickness of 0.1 to 100 nanometers.

[0009] A method for manufacturing a printed circuit board includes the steps of forming a mixture containing a thermosetting composition and a plurality of coated boron nitride particles, and curing the thermosetting composition to form a printed circuit board.

[0010] The above-described features and other features are illustrated by the following drawings, detailed description, and claims.

Brief Description of the Drawings

[0011] The following drawings are exemplary embodiments and are provided to explain the present disclosure. The drawings illustrate examples and are not intended to limit the devices made in accordance with the present disclosure to the materials, conditions, or process parameters described herein.

[0012] [Figure 1] It is a cross-sectional view of an embodiment of a circuit material including a printed circuit board. [Figure 2] It is a diagram of an embodiment of a method for preparing a printed circuit board. [Figure 3] It is a graph of aluminum concentration against the number of cycles of Examples 1 to 6. [Figure 4] It is a graph of surface energy against the number of cycles of Examples 1 to 6. [Figure 5] It is a graph of dielectric breakdown voltage against time for Examples 9 and 11.

Modes for Carrying Out the Invention

[0013] The addition of thermally conductive particles such as boron nitride to polymer composites has been shown to increase the thermal conductivity, but many of these thermally conductive particles have been shown to result in a significant reduction in the copper peel strength with increasing filler loading. This decrease in the copper peel strength with increasing filler loading results from the very low surface energy of boron nitride, a relatively inert surface chemistry that results in a lack of chemical bonding sites, and a smooth basal plane topography that results in an apparent lack of opportunity for chemical bonding or mechanical interlocking sites between boron nitride and its surrounding matrix. In practice, the combination of these features results in poor adhesion between the boron nitride particles and the polymer, which empirically results in boron nitride functioning as voids in the polymer composite.

[0014] It has been discovered that a printed circuit board comprising a plurality of coated boron nitride particles having an average coating thickness of from 0.1 to 100 nanometers (nm) can result in a printed circuit board having improved peel strength. For example, the peel strength between the printed circuit board and the conductive layer can be 3 pounds per linear inch (pli) [0.54 kilograms per linear centimeter (kg / cm)] or more when measured by IPC-TM-650-2.4.8. The printed circuit board can surprisingly retain at least 90%, or from 90 to 99%, of the Z-direction thermal conductivity compared to other similar printed circuit boards prepared from a plurality of uncoated boron nitride particles. "Z-direction thermal conductivity" refers to the thermal conductivity in a direction perpendicular to the plane of the dielectric substrate layer. The disclosed printed circuit board can be useful in overcoming the challenges of thermal management in designing multilayer circuits aimed at further miniaturization and integration of additional components and higher operating frequencies. The Z-direction thermal conductivity is at least 0.8 watts per meter kelvin (W / mK) when measured by ASTM D5470-17, TIM Tester 1300. The printed circuit board can have a water absorption rate of 0.15 wt%, or from 0.01 to 0.1 wt% or less, based on the total weight of the sample when measured in accordance with ASTM D570-98(2018).

[0015] FIG. 1 is a cross-sectional view of a circuit material 40 including a printed circuit board 12 positioned between a first conductive layer 46 and a second conductive layer 46'. It should be understood that in all embodiments described herein, various layers can completely or partially cover each other, and additional copper foil layers, patterned circuit layers, and substrate layers can also be present. It should also be understood that various layers can physically contact directly with an adjacent layer (directly above), or a layer such as an adhesive layer can be disposed therebetween (above). The printed circuit board 12 includes a plurality of coated boron nitride particles 44 and a reinforcing layer 42.

[0016] Multiple coated boron nitride particles may include either single particles (primary particles) or aggregates containing multiple particles (secondary particles), or both. Multiple coated boron nitride particles (primary particles or aggregates of particles) may have average particle sizes of 0.1 to 1,000 micrometers, or 5 to 500 micrometers, or 10 to 250 micrometers, or 25 to 150 micrometers, or 500 nanometers to 100 micrometers, or 3 to 40 micrometers. Multiple coated boron nitride particles may include platelets of irregularly shaped hexagonal boron nitride having an average particle size of 10 micrometers or more. As used herein, “particle size” may refer to the average diameter or equivalent diameter best determined by standard laser particle measurement. Particle size is known as the median diameter or median value of the particle size distribution. 50 It can refer to particle size, which is the particle size value at 50% in the cumulative distribution.

[0017] Multiple coated boron nitride particles may be in the form of at least one of the following: powder (including flakes, platelets, and other shapes), fibers, rods, whiskers, sheets, nanosheets, aggregates, or boron nitride nanotubes (BNNTs), and may vary with respect to crystal type, shape, or size, including the aforementioned distribution. Multiple coated boron nitride particles may have average aspect ratios (ratio of particle width or diameter to length) of 1:2 to 1:100,000, or 1:5 to 1:1,000, or 1:10 to 1:300. Exemplary shapes of particles with particularly high aspect ratios include platelets, rod-shaped particles, fibers, whiskers, etc. Multiple coated boron nitride particles may include coated boron nitride platelets. The exact shape of the platelets is not important. In this regard, coated boron nitride platelets may have irregular shapes. Note that the term “platelet” as used herein generally describes thin, flat particles, including flakes. Platelets can have an average aspect ratio (ratio of particle width to length) of 4:5 to 1:300, or 1:2 to 1:300, or 1:2 to 1:200, or 3:5 to 1:100, or 1:25 to 1:100.

[0018] Regarding the crystal type, coated boron nitride particles can include at least one structure, which is hexagonal, cubic, wurtzite, rhombohedral, or other composite structures. Among the various structures, hexagonal boron nitride particles (hBN) can achieve excellent thermal conductivity, for example, 10 to 300 watts / m·kelvin (W / mK) or more, while cubic particles can achieve very high thermal conductivity of up to 1,300 W / mK. The thermal conductivity of boron nitride particles can be determined according to ASTM E1225-13. Hexagonal boron nitride has a layered structure similar to graphite, with layers stacked and arranged so that the hexagonal rings within the layers coincide. The positions of N and B atoms alternate from layer to layer. Multiple coated boron nitride particles can have a hexagonal structure with a crystallinity index of at least 0.12, or 0.20 to 0.55, or 0.30 to 0.55. hBN particles can be obtained from various commercial sources.

[0019] Crystalline or partially crystalline boron nitride particles can be produced by processes known in the art. These include, for example, boron nitride powder produced from compression processes disclosed in U.S. Patent Nos. 5,898,009 and 6,048,511, aggregated boron nitride powder disclosed in U.S. Patent Application Publication No. 2005 / 0041373, and highly exfoliated boron nitride powder disclosed in U.S. Patent No. 6,951,583. Various boron nitride powders are commercially available, for example, from Momentive under the trade name POLARTHERMA Boron Nitride.

[0020] The plurality of coated boron nitride particles includes a coating. The coating can include at least one of carbon, aluminum, silicon, germanium, copper, nickel, palladium, platinum, iridium, cobalt, iron, ruthenium, molybdenum, tungsten, tantalum, zirconium, or titanium, for example, in at least one form of carbide, oxide, nitride, sulfide, or phosphide. The coating can include at least one of inorganic carbides (such as aluminum carbide or titanium carbide), inorganic oxides (such as aluminum oxide (Al2O3), magnesium oxide, silicon dioxide (SiO2), titanium dioxide, yttrium oxide, zirconium oxide or zinc oxide), inorganic nitrides (such as aluminum nitride (AlN) or silicon nitride), inorganic sulfides (such as gallium sulfide, molybdenum sulfide, or tungsten sulfide), inorganic hydroxides (such as aluminum hydroxide (Al x O y H z )), zinc hydroxide (Zn x O y H z ), or silicon hydroxide (Si x O y H z )), or at least one of inorganic phosphides. The coating can include at least one of silicon dioxide or aluminum oxide.

[0021] The coating can include one or more distinct coating layers that can optionally be alternating layers. For example, the coating can include a first coating layer that includes aluminum oxide and a second coating layer that includes aluminum nitride. In another example, the coating can include a first coating layer that includes aluminum oxide and a second coating layer that includes silicon dioxide. Since aluminum oxide tends to deposit more uniformly on the basal plane of the boron nitride particles than silicon dioxide, both on the basal plane and the edges, and can then function as a seed layer for depositing silicon dioxide, it can be beneficial to first coat the plurality of boron nitride particles with aluminum oxide before depositing the silicon dioxide layer by atomic layer deposition (ALD).

[0022] The coating can be applied over 10 to 100 area percent (A%), 50 to 100 A%, or 90 to 100 A% of the surface. The coating can have a thickness of 0.1 to 100 nm, 0.5 to 30 nm, 1 to 20 nm, or less than 5 nm. The coating can have a thickness of 0.5 to 100 nm, or 1 to 10 nm. Multiple coated boron nitride particles may include coatings of less than 1 wt% (wt%), 0.001 to 0.9 wt%, 0.001 to 0.5 wt%, or 0.005 to 0.1 wt%, based on the total weight of the multiple coated boron nitride particles.

[0023] Multiple coated boron nitride particles can be further surface-treated with a coupling agent. The coupling agent promotes or participates in the formation of covalent bonds that improve adhesion between the filler and the thermosetting polymer matrix. Exemplary coupling agents include silanes, zirconates, titanates, etc., such as vinyltrichlorosilane, vinyltrimethoxysilane, trivinylmethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyl This includes riethoxysilane, N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, bis(trimethoxysilane)benzene, bis(triethoxysilyl)ethylene, triethoxysilyl-modified butadiene, styrylethyltrimethyloxysilane, N-β(aminoethyl)γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, trimethoxyphenylsilane, perfluorocotyltriethoxysilane, and γ-mercaptopropyltrimethoxysilane.

[0024] Coatings can be applied to multiple boron nitride particles via ALD. ALD is a type of chemical vapor deposition in which a thin film is deposited on a substrate using a gas-phase chemical precursor that reacts on the substrate surface. For example, silicon dioxide coatings can be deposited by alternately exposing boron nitride particles to SiCl4 and H2O, and aluminum oxide coatings can be deposited by alternately exposing them to Al(CH3)3 and H2O. A convenient method for applying ultrathin coatings of inorganic materials to multiple boron nitride particles is to form a fluidized bed of particles and then pass various reagents through the fluidized bed under reaction conditions. Methods for fluidizing particulate matter are well known and generally involve supporting the particles on a porous plate or screen. A fluidizing gas can then be passed upward through the plate or screen, lifting the particles somewhat and expanding the volume of the bed. When properly expanded, the particles behave like a fluid. Fluid (gas or liquid) reagents can be introduced into the bed for reaction with the surface of the particles. A method for applying an inorganic material coating may include carrying out the coating reaction in a rotating reactor to uniformly distribute individual particles and expose all particles to the reactants. If necessary, multiple layers of ultrathin coatings can be deposited on multiple coated boron nitride particles. Depositing multiple layers can provide layers with different compositions, for example, alternating compositions.

[0025] After an inorganic coating is formed, one or more reactions can be performed on the thus formed coating to modify it. This technique is useful for creating various types of ultrathin coatings that are not suitable for deposition using atomic layer deposition techniques. For example, various types of ultrathin oxide coatings can be formed using the atomic layer deposition techniques described above, and then carburized to convert the oxide to the corresponding carbide or nitride, or the oxide to the corresponding nitride.

[0026] The boron nitride particles can be heat-treated before or after coating. The heat treatment may include heating the boron nitride particles at a temperature of 100 to 250 degrees Celsius (°C), or 150 to 200°C, for, for example, 4 hours or more, or 6 to 10 hours. Alternatively, the heat treatment may include heating the boron nitride particles at a temperature of 500 to 1,500°C, for, for example, 4 to 18 hours, or 6 to 10 hours. The heat treatment may be carried out in the presence of air, an inert atmosphere, or a vacuum.

[0027] A printed circuit board (PCB) can contain multiple coated boron nitride particles in amounts of 1 to 85 volume percent (vol%), 25 to 80 vol%, or 40 to 60 vol%, based on the total volume of the PCB. A PCB can contain multiple coated boron nitride particles in amounts of 1 to 50 vol%, 5 to 35 vol%, or 10 to 25 vol%, based on the total volume of the PCB. A PCB can contain a thermosetting polymer matrix in amounts of 15 to 99 vol%, 50 to 99 vol%, 65 to 95 vol%, or 75 to 80 vol%, based on the total volume of the PCB. Void spaces can be eliminated in the PCB.

[0028] The printed circuit board may optionally include a reinforcing layer, such as a fiber layer containing multiple thermally stable fibers. The reinforcing layer may be a fabric reinforcement. The fiber layer may be a woven fabric or a nonwoven fabric such as felt. The reinforcing layer can reduce the shrinkage of the printed circuit board when curing in the plane of the material. Furthermore, the use of a reinforcing layer helps to provide a material with relatively high mechanical strength. Such materials can be more easily processed by methods in commercial use, such as lamination including roll-to-roll lamination. The thermally stable fibers may include glass fibers, such as at least one of E glass fibers, S glass fibers, or D glass fibers. The thermally stable fibers may include polymer-based fibers, such as high-temperature polymer fibers. The polymer-based fibers may include liquid crystal polymers such as VECTRAN, which is commercially available from Kuraray America Inc. in Fort Mill, South Carolina. The polymer-based fibers may include at least one of polyetherimide fibers, polyetherketone fibers, polysulfone fibers, polyethersulfone fibers, polycarbonate fibers, or polyester fibers.

[0029] Printed circuit boards may contain multiple uncoated boron nitride particles. In combination with coated boron nitride particles, printed circuit boards may also contain secondary inorganic fillers, particularly dielectric and / or flame-retardant fillers. Secondary inorganic dielectric fillers include titanium dioxide (rutile and anatase), barium titanate, strontium titanate, silica (particles and hollow spheres) including molten amorphous silica, corundum, wollastonite, glass fibers, and Ba2Ti9O 20These may include glass spheres, quartz, boron nitride, aluminum nitride, phosphorus compounds (e.g., flame-retardant phosphorus-containing compounds), brominated compounds (e.g., flame-retardant bromine-containing compounds), silicon carbide, beryllium, alumina, magnesia, mica, talc, nanoclay, aluminosilicates (natural and synthetic), and fused silicon dioxide (e.g., CAB-O-SIL, available from Cabot). Other secondary fillers may include, for example, magnesium hydroxide. Combinations of secondary dielectric fillers may also be used. More specifically, rutile titanium dioxide and amorphous silica are particularly desirable because these fillers have high and low dielectric constants, respectively, thereby enabling a wide range of dielectric constants (e.g., combined with low dielectric loss achieved in the final cured product by adjusting the respective amounts of the two secondary dielectric fillers in the printed circuit board). Specific dielectric fillers include rutile titanium dioxide and amorphous silica. Secondary fillers may be in the form of solid, porous, or hollow particles. When secondary fillers are used, they can be present in amounts of 15 to 60 vol% or 20 to 50 vol% based on the total volume of the printed circuit board.

[0030] Printed circuit boards may contain particulate fluoropolymers. Exemplary particulate fluoropolymers include, but are not limited to, fluorinated homopolymers, such as polytetrafluoroethylene (PTFE), and fluorinated copolymers, such as copolymers of tetrafluoroethylene with perfluoroalkyl vinyl ethers, such as hexafluoropropylene or perfluorooctyl vinyl ether, or copolymers of tetrafluoroethylene with ethylene. Combinations of fluorinated polymers, copolymers, and terpolymers may also be used. Fluoropolymers may be in the form of fine powder, dispersion, or granular form, including fine powder (or "coagulated dispersion") PTFE produced by coagulation and drying of dispersed PTFE, which is generally manufactured to exhibit particle sizes ranging from 400 to 500 micrometers; granular PTFE produced by suspension polymerization, which generally has two different particle size ranges (30 to 40 micrometers for standard products and a median particle size of 400 to 500 micrometers for high bulk density products); and / or copolymers having a tetrafluoroethylene backbone with granular PTFE, fluorinated ethylene-propylene copolymer (FEP), or fully fluorinated alkoxy side chains (PFA). Granular fluoropolymers may be ground at cryogenic temperatures to exhibit a median particle size of less than 100 micrometers.

[0031] If present, the effective particulate fluoropolymer content of the printed circuit board can be readily determined by those skilled in the art, depending on the desired flame retardancy of the composition, the amounts of other components, and other properties desired in the final product. More specifically, the amount of fluoropolymer depends on the amount of coated boron nitride particles, as well as other fillers and particulate flame retardants in the printed circuit board. Generally, the effective amount is 1 to 90 parts by weight (phr), or 5 to 75 phr, or 10 to 50 phr per 100 parts by weight of the thermosetting polymer matrix.

[0032] The polymer matrix may include at least one of the following crosslinked matrices: epoxy, polyphenylene ether, polystyrene, ethylene-propylene dicyclopentadiene copolymer, polybutadiene, polyisoprene, fluoropolymer, poly(ether ether ketone), polyimide, or triallyl cyanurate, triallyl isocyanurate, 1,2,4-trivinylcyclohexane, trimethylolpropane triacrylate, or trimethylolpropane trimethacrylate. The thermosetting polymer matrix may include at least one of epoxy, polybutadiene, or polyisoprene. The polymer matrix may include polyphenylene ether thermosetting resins such as OPE-2ST1200 or OPE-2ST2200 (commercially available from Mitsubishi Gas Chemical Company, Inc.) or NORYL SA9000 (commercially available from SABIC Innovative Plastics). The polymer matrix may include ethylene-propylene dicyclopentadiene copolymer. The thermosetting resin comprises a crosslinking matrix containing a derivative of a crosslinking agent, such as at least one of triallyl cyanurate, triallyl isocyanurate, 1,2,4-trivinylcyclohexane, triallylpropane triacrylate, or trimethylolpropane trimethacrylate. The polymer matrix may contain a thermosetting resin, such as at least one of a fluoropolymer, poly(arylene ether ketone) (e.g., poly(ether ether ketone (PEEK) or poly(ether ketone ketone) (PEKK))), or polyimide (e.g., polyetherimide (PEI) such as ULTEM, commercially available from SABIC Innovative Plastics). The thermosetting resin may contain epoxy.

[0033] As used herein, “fluoropolymers” include fluorinated alpha-olefin monomers, i.e., alpha-olefin monomers containing at least one fluorine atom substituent, and homopolymers and copolymers containing repeating units derived from non-fluorinated ethylenically unsaturated monomers reactive with fluorinated alpha-olefin monomers. Exemplary fluorinated alpha-olefin monomers include CF2=CF2, CHF=CF2, CH2=CF2, CHCl=CHF, CClF=CF2, CCl2=CF2, CClF=CClF, CHF=CCl2, CH2=CClF, CC12=CClF, CF3CF=CF2, CF3CF=CHF, CF3CH=CF2, CF3CH=CH2, CHF2CH=CHF, and CF3CH=CH2, as well as perfluoro(C)methyl vinyl ether, perfluoropropyl vinyl ether, perfluorooctyl vinyl ether, and other perfluoro(C) 2-8This includes alkyl vinyl ethers. In some embodiments, the fluorinated alpha-olefin monomer includes at least one of tetrafluoroethylene (CF2=CF2), chlorotrifluoroethylene (CClF=CF2), (perfluorobutyl)ethylene, vinylidene fluoride (CH2=CF2), or hexafluoropropylene (CF2=CFCF3). Exemplary non-fluorinated monoethylenically unsaturated monomers include ethylene, propylene, butene, and ethylenically unsaturated aromatic monomers such as styrene and alpha-methylstyrene. Exemplary fluoropolymers include poly(chlorotrifluoroethylene) (PCTFE), poly(chlorotrifluoroethylene-propylene), poly(ethylene-tetrafluoroethylene) (ETFE), poly(ethylene-chlorotrifluoroethylene) (ECTFE), poly(hexafluoropropylene), poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-ethylene-propylene), poly(tetrafluoroethylene-hexafluoropropylene) (also known as fluorinated ethylene-propylene copolymer (FEP)), poly(tetrafluoroethylene-propylene) (also known as fluoroelastomer) (FEPM), and poly(tetrafluoro The fluoropolymers include ethylene-perfluoropropylene vinyl ether, copolymers having a tetrafluoroethylene skeleton with fully fluorinated alkoxy side chains (also known as perfluoroalkoxy polymers (PFAs)) (e.g., poly(tetrafluoroethylene-perfluoropropylene vinyl ether)), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-chlorotrifluoroethylene), perfluoropolyethers, perfluorosulfonic acid, or perfluoropolyoxetanes, preferably perfluoroalkoxyalkane polymers, or fluorinated ethylene propylene, more preferably perfluoroalkoxyalkane polymers. Combinations containing at least one of the aforementioned fluoropolymers can be used. In some embodiments, the fluoropolymer is FEP, PFA, ETFE, or PTFE, which may be fibrillating or non-fibrillating.FEP is available under the brand names TEFLON® FEP from DuPont or NEOFLON FEP from Daikon, and PFA is available under the brand names NEOFLON PFA from Daikin, TEFLON® PFA from DuPont, or HYFLON PFA from Solvay Solexis.

[0034] The thermosetting resin may contain at least one homopolymer or copolymer comprising units derived from at least one of butadiene or isoprene. Units derived from other copolymerizable monomers may also be present in the thermosetting polymer, for example, in the form of the polymer's main chain or grafts. The copolymerizable monomers include, but are not limited to, substituted and unsubstituted monovinyl aromatic monomers such as vinyl aromatic monomers, e.g., at least one of styrene, 3-methylstyrene, 3,5-diethylstyrene, 4-n-propylstyrene, alpha-methylstyrene, alpha-methylvinyltoluene, para-hydroxystyrene, para-methoxystyrene, alpha-chlorostyrene, alpha-bromostyrene, dichlorostyrene, dibromostyrene, tetra-chlorostyrene, etc., or substituted and unsubstituted divinyl aromatic monomers such as divinylbenzene and divinyltoluene. Combinations containing at least one of the aforementioned copolymerizable monomers may also be used. The thermosetting polymer matrix may include, but is not limited to, at least one of the following: epoxy resin, butadiene homopolymer, isoprene homopolymer, butadiene-vinyl aromatic copolymer such as butadiene-styrene, isoprene-vinyl aromatic copolymer such as isoprene-styrene copolymer, etc.

[0035] Polybutadiene and / or polyisoprene may be present in the thermosetting polymer matrix in amounts of up to 100 wt%, up to 75 wt%, or 10 to 70 wt%, or 20 to 60 or 70 wt%, relative to the total weight of the thermosetting polymer matrix (excluding filler or reinforcing layers). The thermosetting polymer matrix may have 1,2-additions at least 90 wt%, based on the total repeating units, which can result in a high crosslink density upon curing due to the numerous pendant vinyl groups available for crosslinking.

[0036] Other polymers that can co-cure with a thermosetting polymer matrix may exist for specific property or treatment modifications. For example, lower molecular weight ethylene-propylene elastomers can be used to improve the stability of the dielectric strength and mechanical properties over time in electrical substrate materials. The ethylene-propylene elastomers used herein are copolymers such as terpolymers, or other polymers that primarily contain ethylene and propylene. Ethylene-propylene elastomers can be further classified as EPM copolymers (i.e., copolymers of ethylene and propylene monomers) or EPDM terpolymers (i.e., terpolymers of ethylene, propylene, and diene monomers). Ethylene-propylene-diene terpolymer rubbers have a saturated main chain, along with unsaturated components available away from the main chain for easy crosslinking. Liquid ethylene-propylene-diene terpolymer rubbers can be used, where the diene is dicyclopentadiene.

[0037] The molecular weight of ethylene-propylene rubber may be a viscosity-average molecular weight (Mv) of 10,000 grams / mol (g / mol) or less. When measured by gel permeation chromatography based on a polycarbonate standard, ethylene-propylene rubber may have a weight-average molecular weight (Mw) of 50,000 g / mol or less. Ethylene-propylene rubber may include ethylene-propylene rubber with an Mv of 7,200 g / mol, available from Lion Copolymer in Baton Rouge, Louisiana, under the trade name TRILENE CP80; liquid ethylene-propylene-dicyclopentadiene terrpolymer rubber with an Mv of 7,000 g / mol, available from Lion Copolymer under the trade name TRILENE 65; and liquid ethylene-propylene-ethylidene norborneneter polymer with an Mv of 7,500 g / mol, available from Lion Copolymer under the name TRILENE 67.

[0038] Ethylene-propylene rubber can be present in amounts effective for maintaining the stability of the substrate material's properties, particularly its dielectric strength and mechanical properties, over time. Typically, such amounts are up to 20% by weight, or 4 to 20% by weight, or 6 to 12% by weight, relative to the total weight of the thermosetting polymer matrix.

[0039] Another type of co-curable polymer is an unsaturated polybutadiene or polyisoprene-containing elastomer. This component may be a random or block copolymer of mainly 1,3-addition butadiene or isoprene having an ethylenically unsaturated monomer, a vinyl aromatic compound such as styrene or alpha-methylstyrene, an acrylate or methacrylate such as methyl methacrylate, or acrylonitrile. The elastomer may be a solid thermoplastic elastomer comprising a linear or graft-type block copolymer having a polybutadiene or polyisoprene block and a thermoplastic block that may be derived from a monovinyl aromatic monomer such as styrene or alpha-methylstyrene. This type of block copolymer includes, for example, styrene-butadiene-styrene triblock copolymer, available from Dexco Polymers in Houston, Texas, under trade name VECTOR 8508M, from Enichem Elastomers America in Houston, Texas, under trade name SOL-T-6302, and from Dynasol Elastomers under trade name CALPRENE401, as well as styrene-butadiene diblock copolymer and mixed triblock and diblock copolymers containing styrene and butadiene, available from Kraton Polymers (Houston, Texas) under trade name KRATON D1118. KRATON D1118 is a mixed diblock / triblock styrene and butadiene-containing copolymer containing 33 wt% styrene based on the total weight of the copolymer.

[0040] Optional polybutadiene or polyisoprene-containing elastomers may further contain a second block copolymer similar to those described above, except that the polybutadiene or polyisoprene block is hydrogenated to form a polyethylene block (in the case of polybutadiene) or an ethylene-propylene copolymer block (in the case of polyisoprene). When used in conjunction with the above copolymers, materials with higher toughness can be produced. An example of this type of second block copolymer is KRATON GX1855 (commercially available from Kraton Polymers), which is considered to be a mixture of styrene-high 1,2-butadiene-styrene block copolymer and styrene-(ethylene-propylene)-styrene block copolymer.

[0041] Unsaturated polybutadiene or polyisoprene-containing elastomer components may be present in the polymer matrix composition in amounts of 2 to 60 wt%, 5 to 50 wt%, 10 to 40 wt%, or 10 to 50 wt%, relative to the total weight of the thermosetting polymer matrix.

[0042] Further co-curable polymers that can be added for specific properties or processing modifications include, but are not limited to, homopolymers or copolymers of ethylene such as polyethylene and ethylene oxide copolymers, norbornene polymers such as natural rubber and polydicyclopentadiene, styrene-isoprene-styrene copolymers and butadiene-acrylonitrile copolymers, and unsaturated polyesters. The level of these copolymers is generally 50 wt% or less of the total weight of the thermosetting polymer matrix.

[0043] Free radical curable monomers may also be added to modify specific properties or treatments, for example, to increase the crosslinking density of the system after curing. Suitable crosslinking monomers include, for example, di, tri, or higher ethylenically unsaturated monomers such as divinylbenzene, trivinylbenzene, triallyl cyanurate, diallyl phthalate, and polyfunctional acrylate monomers (e.g., SARTOMER polymers available from Sartomer USA in Newtown Square, Pennsylvania), or combinations thereof, all of which are commercially available. When used, crosslinking agents may be present in the polymer matrix composition in amounts up to 20 wt%, or 1 to 15 wt%, based on the total weight of the thermosetting polymer matrix.

[0044] A curing agent can be added to the thermosetting composition before curing to accelerate the curing reaction of polyenes having olefin-reactive sites. The curing agent may include organic peroxides, such as dicumyl peroxide, t-butyl perbenzoate, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, α,α-di-bis(t-butylperoxy)diisopropylbenzene, or 2,5-dimethyl-2,5-di(t-butylperoxy)hexine-3. A carbon-carbon initiator, such as 2,3-dimethyl-2,3-diphenylbutane, can also be used. The curing agent or initiator may be used alone or in combination. The amount of curing agent may range from 1.5 to 10 wt% based on the total weight of the thermosetting polymer matrix.

[0045] The thermosetting polymer matrix can also be modified. For example, the thermosetting polymer matrix can have carboxylate ends, hydroxyl group ends, methacrylate ends, etc. Post-reaction polymers such as epoxy, maleic anhydride, or urethane-modified polymers of butadiene or isoprene polymers can be used. The thermosetting polymer matrix can also be crosslinked with divinyl aromatic compounds, such as divinylbenzene, e.g., polybutadiene-styrene crosslinked with divinylbenzene. The polymer is broadly classified as "polybutadiene" by manufacturers, e.g., Nippon Soda in Tokyo, Japan and Cray Valley Hydrocarbon Specialty Chemicals in Exton, Pennsylvania. Mixtures of polymers, e.g., mixtures of polybutadiene homopolymer and poly(butadiene-isoprene) copolymer can also be used. Combinations including syndiotactic polybutadiene may also be useful.

[0046] Thermosetting polymer matrices can be carboxylated. Functionalization can be achieved using polyfunctional compounds having both (i) a carbon-carbon double bond or carbon-carbon triple bond and (ii) at least one carboxyl group, including carboxylic acids, anhydrides, amides, esters, or acid halides, within the molecule. The specific carboxyl group is a carboxylic acid or an ester. Examples of polyfunctional compounds that can provide carboxylic acid functional groups include maleic acid, maleic anhydride, fumaric acid, and citric acid. In particular, polybutadiene with maleic anhydride added can be used in thermosetting compositions. Suitable maleated polybutadiene polymers are commercially available, for example, from Cray Valley under the trade names RICON 130MA8, RICON 130MA13, RICON 130MA20, RICON 131MA5, RICON 131MA10, RICON 131MA17, RICON 131MA20, and RICON 156MA17. A suitable maleated polybutadiene-styrene copolymer is commercially available, for example, from Sartomer under the trade name RICON 184MA6 (a butadiene-styrene copolymer with maleic anhydride added, having a styrene content of 17 to 27 wt% and a number-average molecular weight (Mn) of 9,900 g / mol).

[0047] The relative amounts of various polymers in a thermosetting polymer matrix, such as polybutadiene or polyisoprene polymers and other polymers, may depend on the desired properties of the specific conductive metal layer, circuit material, and copper-clad laminate used, as well as similar considerations. For example, the use of poly(arylene ether) can provide increased bonding strength to the conductive metal layer, e.g., copper. The use of polybutadiene and / or polyisoprene can increase the high-temperature resistance of the laminate, for example, if these polymers are carboxy-functionalized. The use of elastomer block copolymers can function to make the components of the polymer matrix compatible. Determining the appropriate amount of each component can be done without excessive experimentation, depending on the properties desired for a particular application.

[0048] Generally, printed circuit boards can be prepared by first mixing all components, including, for example, monomers, coated boron nitride particles, an optional secondary filler, an optional coupling agent (e.g., at least one of silane, zirconate, or titanate), an optional solvent, and an optional curing agent. Mixing can be continued to form a slurry or dispersion, with each component uniformly dispersed throughout the mixture. In applications where the mixture is impregnated into a reinforcing layer to form a prepreg, conventional prepreg manufacturing methods can be used. Typically, the reinforcing layer is impregnated with the mixture, weighed to the precise thickness, and then the solvent is removed to form a prepreg. If the prepreg contains a particular thermosetting polymer, it can be optionally B-staged to form a partially cured layer before being used to form a circuit subassembly.

[0049] To adjust the viscosity of the mixture, a solvent or dispersion medium may be optionally present. The solvent can be selected to have an evaporation rate convenient for dissolving or dispersing the components of the mixture, for example, for coating and drying the mixture on a reinforcing layer. A non-exclusive list of possible solvents and dispersion media includes at least one of water, xylene, toluene, methyl ethyl ketone, methyl isobutyl ketone, hexane, or higher-order liquid linear alkanes such as heptane, octane, nonane, cyclohexane, isophorone, or various terpene-based solvents. Specific solvents and dispersion media for thermosetting compositions may include at least one of xylene, toluene, methyl ethyl ketone, methyl isobutyl ketone, or hexane, more specifically, at least one of xylene or toluene.

[0050] Figure 2 shows an example of a method for fabricating a printed circuit board. In Figure 2, the reinforcing layer is unwound from the roll 10, passes through the accumulator 12, and enters the coating region 16. In the coating region 16, the coating mixture in the tank 20 rises so that the reinforcing layer passes through the coating mixture and coats the reinforcing material with the coating mixture. The reinforcing layer then passes through the metering roll 22 to help ensure uniform coating of the coating mixture on the reinforcing layer. After coating, the reinforcing layer passes through the drying tower 18 to evaporate any present solvent and help at least partially cure the polymer matrix. Finally, the reinforcing layer traverses around the drive roll 28, passes through the accumulator 30, and eventually goes onto the coating roll 32. Many variations of this coating procedure can be implemented, and this example is provided merely as a non-limiting embodiment of the coating method.

[0051] The article may include a printed circuit board. The article may be a bond ply, a cover film, or a build-up material, which, when combined with a conductive layer, can provide a circuit laminate, a resin-coated cap layer, or a circuit subassembly. The circuit material may include a printed circuit board having a conductive layer disposed on one or both of its broad surfaces. Useful conductive layers include, for example, at least one of stainless steel, copper, gold, silver, aluminum, zinc, tin, lead, or transition metals. There are no particular restrictions regarding the thickness of the conductive layer, nor are there any restrictions regarding the shape, size, or texture of the surface of the conductive layer. The conductive layer may have a thickness of 3 to 200 micrometers, or 9 to 180 micrometers. If there are two or more conductive layers, the thicknesses of the two layers may be the same or different. The conductive layer may include a copper layer. A suitable conductive layer includes a thin layer of a conductive metal, such as copper foil, which is currently used in circuit formation, e.g., electrodeposited copper foil. The copper foil can have a root mean square (RMS) roughness of 2 micrometers or less, or 0.7 micrometers or less, and the roughness is measured using white light interferometry with a Veeco Instruments WYCO Optical Profiler.

[0052] The conductive layer can be applied by directly laser structuring, by laminating the conductive layer onto the printed circuit board, by placing the conductive layer in the mold prior to reaction injection molding, or by bonding the conductive layer to the printed circuit board via an adhesive layer. Other methods known in the art, such as electrodeposition and chemical vapor deposition, can be used to apply the conductive layer, depending on the form of the specific material and circuit material.

[0053] Lamination inevitably involves laminating a multilayer stack, which includes a printed circuit board, a conductive layer, and an optional intermediate layer between the printed circuit board and the conductive layer, in order to form a layered structure. The conductive layer can be in direct contact with the printed circuit board without an intermediate layer. The layered structure can then be placed in a press, such as a vacuum press, for a period of time and under pressure and temperature suitable for bonding the layers together to form a laminate. Lamination and optional curing can be done by a one-step process, for example, by using a vacuum press, or by a multi-step process. In a one-step process, the layered structure can be placed in a press, raised to a lamination pressure (e.g., 150 to 2,500 pounds / square inch (psi) [1 to 17 megapascals]), and heated to a lamination temperature (e.g., 150 to 390°C). The lamination temperature and pressure can be maintained for a desired immersion time, i.e., 20 minutes, and then cooled to below 150°C (while still under pressure).

[0054] If present, the intermediate layer may include a polyfluorocarbon film that can be placed between the conductive layer and the substrate layer, and an optional layer of microglass-reinforced fluorocarbon polymer may be placed between the polyfluorocarbon film and the conductive layer. The layer of microglass-reinforced fluorocarbon polymer can increase the adhesion of the conductive layer to the substrate. Microglass may be present in an amount of 4 to 30 wt%, based on the total weight of the layer. Microglass may have a maximum length scale of 900 micrometers or less, or 500 micrometers or less. Microglass may be of the type commercially available from Johns-Manville Corporation in Denver, Colorado. The polyfluorocarbon film includes fluoropolymers (polytetrafluoroethylene (PTFE), fluorinated ethylene-propylene copolymers (TEFLON® FEP, etc.), and copolymers having a tetrafluoroethylene backbone with fully fluorinated alkoxy side chains (TEFLON® PFA, etc.)).

[0055] The conductive layer can be applied by laser direct structuring. Here, the printed circuit board may include a laser direct structuring additive, and the laser direct structuring may include irradiating the surface of the substrate with a laser, forming tracks of the laser direct structuring additive, and applying a conductive metal to the tracks. The laser direct structuring additive may include metal oxide particles (such as titanium oxide and copper-chromium oxide). The laser direct structuring additive may include spinel-based inorganic metal oxide particles such as spinel copper. The metal oxide particles may be coated with a composition containing, for example, tin and antimony (e.g., 50 to 99 wt% tin and 1 to 50 wt% antimony based on the total weight of the coating). The laser direct structuring additive may contain 2 to 20 parts of the additive based on 100 parts of each composition. Irradiation can be carried out using a YAG laser with a wavelength of 1,064 nanometers, a frequency of 80 kilohertz (kHz), and a speed of 3 meters / second at an output of 10 watts. Conductive metals can be applied using a plating process in an electroless plating bath containing, for example, copper.

[0056] The conductive layer can be applied by adhesive bonding. The conductive layer may be a circuit (a metallized layer of another circuit), for example, a flexible circuit. The adhesive layer may be placed between one or more conductive layers and the substrate. Where appropriate, the adhesive layer may contain poly(arylene ether) and a carboxy-functionalized polybutadiene or polyisoprene polymer containing butadiene, isoprene, or butadiene and isoprene units, as well as 0 to 50 wt% co-curable monomer units. The adhesive layer may be present in an amount of 2 to 15 grams / square meter. Poly(arylene ether) may include carboxy-functionalized poly(arylene ether). Poly(arylene ether) may be a reaction product of poly(arylene ether) and a cyclic anhydride, or a reaction product of poly(arylene ether) and maleic anhydride. The carboxy-functionalized polybutadiene or polyisoprene polymer may be a carboxy-functionalized butadiene-styrene copolymer. Carboxylated polybutadiene or polyisoprene polymers may be reaction products of polybutadiene or polyisoprene polymers with cyclic anhydrides. Carboxylated polybutadiene or polyisoprene polymers may be maleated polybutadiene-styrene or maleated polyisoprene-styrene copolymers.

[0057] The following examples are provided to illustrate the present disclosure. The examples are illustrative and are not intended to limit devices fabricated in accordance with the present disclosure to the materials, conditions, or process parameters described herein.

[0058] Examples In the examples, copper peel strength was measured according to IPC-TM-650-2.4.8 after thermal stress, including 10 seconds of exposure to molten solder at 288°C. Relative permittivity and dielectric loss were measured according to IPC-TM-650-2.5.5.5. Dielectric strength was measured according to IPC-TM-650-2.5.6.2. Water absorption was measured according to ASTM D570-98(2018) using a test specimen of nominal thickness 1.52 mm after immersion at 50°C for 48 hours. Thermal conductivity is the Z-direction thermal conductivity measured according to ASTM D5470-17, TIM tester 1300.

[0059] Examples 1-6: Effect of coating thickness on coated hexagonal boron nitride The surface of the hexagonal boron nitride particles was coated with aluminum oxide by atomic layer deposition (ALD) using trimethylaluminum and water as precursors. The boron nitride powder used was PBN20, a high-density aggregate of hexagonal boron nitride platelets supplied by Zibo Jonye Ceramics Technology Company. PBN20 has a typical median particle size of 18 to 22 micrometers and a density of 6.2 square meters / gram (m²). 2 The specific surface area (mJ / g) is shown. A series of coated powders were produced with different coating thicknesses by stepwise changing the number of ALD cycles. The aluminum content of the coated powders was determined by ICP analysis, and the surface energy was measured by the Washburn wicking method for contact angles with various probe liquids. The contact angle measurements were combined with Fowkes theory to decompose the surface energy into dispersion and polar components. The results are shown in Table 1, Figures 3 and 4, in mJ / m 2 mJ / sqm represents millijoules per square meter, and ppm represents parts per million based on the total weight of the sample.

[0060] [Table 1]

[0061] Table 1 and Figure 3 show that the amount of deposited aluminum is well controlled throughout the ALD cycle. Without being constrained by theory, this self-regulation appears to be due to a surface reaction in which trimethylaluminum and water are self-regulating.

[0062] Table 1 and Figure 4 show that the uncoated Example 1 exhibited the lowest overall surface energy, dispersion surface energy (upper curve in Figure 4), and surface polarity (lower curve in Figure 4). The surface polarity of the uncoated boron nitride is thought to be essentially due to the presence of boron oxide on the surface. It can be seen that coating provides a method for modifying the surface polarity of the boron nitride filler. The increase in surface polarity may be due to the presence of hydroxyl groups on the surface of the coating.

[0063] Example 7: Printed circuit board containing coated boron nitride Printed circuit boards containing 15 vol% coated boron nitride and 85 vol% RO4000 (commercially available from Rogers Corporation) were prepared based on the total volume of the substrate minus the glass fiber reinforcement layer. The coated boron nitride was prepared by coating boron nitride powder (Momentive PT-120) with an aluminum oxide ALD coating over 10 cycles. The thickness of the aluminum oxide coating was 5 nm. Thermal conductivity and peel strength are shown in Table 2.

[0064] Example 8: Printed circuit board containing uncoated boron nitride Printed circuit boards containing 15 vol% uncoated boron nitride and 85 vol% RO4000 (commercially available from Rogers Corporation) were prepared. The uncoated boron nitride was Momentive PT-100. Thermal conductivity and peel strength are shown in Table 2.

[0065] [Table 2]

[0066] Table 2 shows that the peel strength of the printed circuit board of Example 7, which contains coated boron nitride, was significantly improved compared to the printed circuit board of Example 8, which contains the same amount of boron nitride but is not coated.

[0067] Examples 9-11: Effects of coated boron nitride in multilayer composite materials Dielectric substrates containing 17.3 vol% PBN20 and 27.6 vol% molten amorphous silica particles were fabricated in 1674-style glass fiber fabric using a conventional solution prepreg process. Prepreg materials were prepared both as-received boron nitride aggregates and aggregates coated with aluminum oxide using four ALD cycles (coating thickness 0.4 nm). The nominal compositions of the prepreg materials are shown in Table 3, and the polymer blends consist of a mixture of 1,2-polybutadiene (NISSO-PB B-3000), butadiene-styrene block copolymer (KRATON D1118 ET), and EPDM terpolymer (TRILENE 65) in amounts sufficient to form a continuous phase.

[0068] [Table 3]

[0069] Multiple sheets of the obtained prepreg material, having a nominal press thickness of 0.25 mm (0.010 inches), were stacked and laminated onto 1.0 ounce / square foot (305 grams / square meter) electrodeposited copper foil to produce test panels with nominal core thicknesses of 0.508 mm (0.020 inches) and 1.52 mm (0.060 inches). A summary of the properties of Examples 9 and 10, including uncoated boron nitride and coated boron nitride, respectively, is shown in Table 4, where kV / cm represents kilovolts / centimeter.

[0070] [Table 4]

[0071] Table 4 shows that Example 10, which includes coated boron nitride, exhibited greater dielectric breakdown strength and lower water absorption, demonstrating an improved filler at the polymer interface. Table 4 also shows lower water absorption compared to Example 9. This lower water absorption is particularly important because the printed circuit process involves immersion in a water bath, and the intrusion of ionic materials can adversely affect electrical performance. These advantages were achieved without significantly impacting the thermal conductivity in the Z direction.

[0072] In addition to beneficial effects on dielectric strength and water absorption, long-term resistance to thermal oxidative degradation at elevated temperatures can be significantly improved through the use of coated boron nitride. Figure 5 illustrates that the dielectric substrate of Example 11, which includes coated boron nitride, shows a fourfold increase in dielectric strength half-life when continuously exposed to 200°C. Specifically, Figure 5 shows that the half-lives of Example 9 (lower curve), which includes uncoated boron nitride, and Example 11 (upper curve), which includes coated boron nitride with a thickness of 0.51 mm (0.020 inches), are 980 hours and 4,200 hours, respectively.

[0073] The following are some non-limiting aspects of this disclosure.

[0074] Embodiment 1A: A printed circuit board comprising a polymer matrix, a reinforcing layer, and a plurality of coated boron nitride particles, wherein the plurality of coated boron nitride particles include a coating having an average coating thickness of 0.5 to 100 nanometers or 1 to 100 nanometers.

[0075] Embodiment 1B: A printed circuit board comprising a polymer matrix comprising at least one of a crosslinking matrix comprising at least one of epoxy, polyphenylene ether, polystyrene, ethylene-propylenedicyclopentadiene copolymer, polybutadiene, polyisoprene, fluoropolymer, or triallyl cyanurate, triallyl isocyanurate, 1,2,4-trivinylcyclohexane, trimethylolpropane triacrylate, or trimethylolpropane trimethacrylate, a reinforcing layer, and a plurality of coated boron nitride particles, wherein the plurality of coated boron nitride particles comprises a coating having an average coating thickness of 0.5 to 100 nanometers or 1 to 100 nanometers.

[0076] Embodiment 1C: A printed circuit board comprising a thermosetting polymer matrix comprising at least one of epoxy, polybutadiene, or polyisoprene, a reinforcing layer, and a plurality of coated boron nitride particles, wherein the plurality of coated boron nitride particles include a coating having an average coating thickness of 0.5 to 100 nanometers or 1 to 100 nanometers.

[0077] Embodiment 2: A printed circuit board according to Embodiment 1, wherein a plurality of coated boron nitride particles have an average particle size of 0.1 to 1,000 micrometers, or 5 to 500 micrometers, or 25 to 150 micrometers, or 3 to 40 micrometers.

[0078] Embodiment 3: One or more printed circuit boards of any of the above embodiments, wherein the coating comprises at least one of inorganic carbides, inorganic oxides, inorganic nitrides, inorganic sulfides, inorganic hydroxides, or inorganic phosphides. If present, the inorganic hydroxide may include at least one of aluminum hydroxide, zinc hydroxide, or silicon hydroxide.

[0079] Embodiment 4: A printed circuit board of any one or more of the above embodiments, wherein the coating comprises at least one of silicon dioxide or aluminum oxide.

[0080] Embodiment 5: A printed circuit board having a thickness of 0.5 to 30 nm, or 1 to 20 nm, or 5 nm or less, one or more of the above embodiments.

[0081] Embodiment 6: One or more printed circuit boards according to any of the above embodiments, wherein the coating is distributed over 10 to 100A%, 50 to 100A%, or 90 to 100A% of the surface of a plurality of boron nitride particles.

[0082] Embodiment 7: A printed circuit board of any one or more of the above embodiments, wherein the plurality of coated boron nitride particles include coatings of less than 1 wt%, or 0.001 to 0.9 wt%, or 0.001 to 0.5 wt%, or 0.005 to 0.1 wt%, based on the total weight of the plurality of coated boron nitride particles.

[0083] Embodiment 8: A printed circuit board comprising a plurality of coated boron nitride particles, including ALD-coated particles, one or more of the above embodiments.

[0084] Embodiment 9: One or more printed circuit boards according to any one of the above embodiments, wherein the printed circuit board contains a plurality of coated boron nitride particles in an amount of 1 to 85 vol%, or 1 to 50 vol%, or 5 to 35 vol%, or 10 to 25 vol%, based on the total volume of the printed circuit board.

[0085] Embodiment 10: One or more printed circuit boards according to any one of the above embodiments, wherein the printed circuit board comprises a thermosetting polymer matrix in an amount of 15 to 99 vol%, or 50 to 99 vol%, or 65 to 95 vol%, or 75 to 80 vol%, based on the total volume of the printed circuit board.

[0086] Embodiment 11: A printed circuit board comprising a reinforcing layer containing multiple glass fibers, one or more of the above embodiments.

[0087] Embodiment 12: One or more printed circuit boards according to any of the above embodiments, wherein the thermosetting polymer matrix comprises at least one of epoxy resin, butadiene homopolymer, isoprene homopolymer, butadiene-vinyl aromatic copolymer, or isoprene-vinyl aromatic copolymer. The thermosetting polymer matrix may include epoxy resin. The thermosetting polymer matrix may include polybutadiene. The thermosetting polymer matrix may include polyisoprene.

[0088] Embodiment 13: A printed circuit board having a peel strength of 3 pli or more, as determined in accordance with IPC-TM-650-2.4.8, one or more printed circuit boards according to any one of the above embodiments.

[0089] Embodiment 14: A circuit material comprising one or more printed circuit boards according to the embodiments described above, and a conductive layer disposed on at least one surface of the printed circuit board.

[0090] Embodiment 15: A method for producing one or more printed circuit boards according to any of the above embodiments, comprising the steps of: forming a mixture containing a thermosetting composition and a plurality of coated boron nitride particles; coating a reinforcing layer with the mixture; and curing the thermosetting composition to form a printed circuit board.

[0091] Embodiment 16: The method of Embodiment 15, wherein the step of coating the reinforcing layer includes at least one of dip coating, roll-over knife coating, roll-to-roll coating, etc.

[0092] Embodiment 17: The method of Embodiment 16, further comprising the step of coating the reinforcing layer, which includes first unfolding the reinforcing layer from a first roll, passing the reinforcing layer through the mixture, passing the reinforcing layer through a solvent-drying section to at least partially cure the thermosetting mixture, and winding the coated reinforcing layer onto a second roll to roll-to-roll coat the reinforcing layer with the mixture.

[0093] Embodiment 18: One or more methods from any one of Embodiments 15 to 17, wherein the curing step includes partially curing to form a prepreg.

[0094] Embodiment 19: One or more methods from any one of embodiments 15 to 18, further comprising depositing a conductive layer on at least one surface of a printed circuit board.

[0095] Embodiment 20: One or more methods from any one of embodiments 15 to 19, further comprising depositing a coating on a plurality of boron nitride coated particles by atomic layer deposition before forming a mixture.

[0096] Compositions, methods, and articles may, alternatively, include, consist of, or essentially consist of any suitable materials, steps, or components disclosed herein. Compositions, methods, and articles may, additionally or alternatively, be designed to lack or substantially include materials (or types), steps, or components that are not necessary for achieving the function or purpose of the composition, method, and article.

[0097] Where used herein, “a,” “an,” “the,” and “at least one” are not intended to indicate a limit on quantity, but rather to encompass both singular and plural forms unless the context clearly indicates otherwise. For example, “element” is synonymous with “at least one element” unless the context clearly indicates otherwise. The term “or” means “and / or” unless the context clearly indicates otherwise. Throughout the specification, references such as “aspect,” “embodiment,” “another embodiment,” and “some embodiments” mean that a particular element (e.g., feature, structure, step, or characteristic) described in relation to an embodiment may be included in at least one embodiment described herein and may or may not be present in other embodiments. In addition, it should be understood that the elements described may be combined in any suitable way in various embodiments.

[0098] When an element such as a layer, film, region, or substrate is described as being "on top of" another element, it can be directly on top of the other element, or there may be an intervening element. In contrast, when an element is described as being "directly on top of" another element, there is no intervening element.

[0099] In general, compositions, methods, and articles may, by alternative means, include, consist of, or essentially consist of any of the components, steps, or elements disclosed herein. Compositions, methods, and articles may, additionally or alternatively, be designed, implemented, or manufactured to lack, or substantially include, any components, steps, or elements not necessary for achieving the function or purpose of the claims.

[0100] Unless otherwise specified herein, all test standards are the most current standards in effect as of the filing date of this application or, if priority is claimed, as of the filing date of the earliest priority application in which the test standard appears.

[0101] The endpoints of all ranges directed toward the same component or characteristic include the endpoints, can be combined independently, and include all intermediate points and ranges. For example, the range "up to 25 wt%, or 5 to 20 wt%" includes the endpoints and all intermediate values ​​of the range "5 to 25 wt%", e.g., 10 to 23 wt%.

[0102] The term “combination” includes blends, mixtures, alloys, reaction products, etc. Also, “at least one of the” means that the list includes each element individually, combinations of two or more elements in the list, and combinations of at least one element in the list with an unnamed similar element.

[0103] Unless otherwise defined, technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which this invention belongs.

[0104] All cited patents, patent applications, and other documents are incorporated herein by reference in their entirety. However, in the event that any terminology in this application conflicts with or is inconsistent with any terminology in any incorporated document, the terminology in this application shall prevail over the conflicting terminology in any incorporated document.

[0105] While specific embodiments are described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently anticipated or may not be anticipated may arise for the applicant or others in the art. Accordingly, the claims at the time of filing, and any appended claims that may be amended, are intended to encompass all such alternatives, modifications, variations, improvements, and substantial equivalents. [Explanation of Symbols]

[0106] 10 rolls 12 Printed circuit boards 12 Accumulators 16 Covered area 18 Drying Tower 20 tanks 22 Measuring Rolls 28 Drive Roll 30 Accumulators 32 Covering Rolls 40 Circuit materials 42 Reinforcement layer 44 Multiple coated boron nitride particles 46 First conductive layer 46' Second conductive layer

Claims

1. A polymer matrix comprising at least one of the following crosslinked matrices: epoxy, polyphenylene ether, polystyrene, ethylene-propylenedicyclopentadiene copolymer, polybutadiene, polyisoprene, fluoropolymer, or triallyl cyanurate, triallyl isocyanurate, 1,2,4-trivinylcyclohexane, trimethylolpropane triacrylate, or trimethylolpropane trimethacrylate; Reinforcement layer, A printed circuit board comprising a plurality of coated boron nitride particles, The plurality of coated boron nitride particles comprises boron nitride particles and a coating having an average coating thickness of 0.5 to 100 nanometers. The coating comprises at least a first coating layer deposited directly on the boron nitride particles, and a second coating layer on the first coating layer that is different from the first coating layer. A printed circuit board in which the first coating layer contains aluminum oxide.

2. The printed circuit board according to claim 1, wherein the plurality of coated boron nitride particles have an average particle size of 0.1 to 1,000 micrometers, or 5 to 500 micrometers, or 25 to 150 micrometers, or 3 to 40 micrometers.

3. A polymer matrix comprising at least one of the following crosslinked matrices: epoxy, polyphenylene ether, polystyrene, ethylene-propylenedicyclopentadiene copolymer, polybutadiene, polyisoprene, fluoropolymer, or triallyl cyanurate, triallyl isocyanurate, 1,2,4-trivinylcyclohexane, trimethylolpropane triacrylate, or trimethylolpropane trimethacrylate; Reinforcement layer, A printed circuit board comprising a plurality of coated boron nitride particles, The plurality of coated boron nitride particles include a coated substrate comprising aluminum oxide and silicon dioxide, having an average coating thickness of 0.5 to 100 nanometers, on a printed circuit board.

4. The printed circuit board according to any one of claims 1 to 3, wherein the average coating thickness is 0.5 to 30 nm or 1 to 20 nm.

5. The printed circuit board according to any one of claims 1 to 4, wherein the coating is arranged over 10 to 100A%, 50 to 100A%, or 90 to 100A% of the total surface area of ​​the plurality of coated boron nitride particles.

6. The printed circuit board according to any one of claims 1 to 5, wherein the plurality of coated boron nitride particles include a coating of less than 1 wt%, or 0.001 to 0.9 wt%, or 0.001 to 0.5 wt%, or 0.005 to 0.1 wt%, based on the total weight of the plurality of coated boron nitride particles.

7. The printed circuit board according to any one of claims 1 to 6, wherein the plurality of coated boron nitride particles include ALD coated particles.

8. The printed circuit board according to any one of claims 1 to 7, wherein the printed circuit board comprises 1 to 85 vol%, or 1 to 50 vol%, or 5 to 35 vol%, or 10 to 25 vol%, of the plurality of coated boron nitride particles based on the total volume of the printed circuit board.

9. The printed circuit board according to any one of claims 1 to 8, wherein the printed circuit board comprises 15 to 99 vol%, or 50 to 99 vol%, or 65 to 95 vol%, or 75 to 80 vol%, of a thermosetting polymer matrix based on the total volume of the printed circuit board.

10. The printed circuit board according to any one of claims 1 to 9, wherein the reinforcing layer comprises a plurality of glass fibers.

11. The printed circuit board according to any one of claims 1 to 10, wherein the polymer matrix comprises at least one of epoxy, butadiene homopolymer, isoprene homopolymer, butadiene-vinyl aromatic copolymer, or isoprene-vinyl aromatic copolymer.

12. The printed circuit board according to any one of claims 1 to 11, wherein the printed circuit board has a peel strength of 3 pli [0.54 kilograms / linear centimeter] or more, as determined in accordance with IPC-TM-650-2.4.

8.

13. A circuit material comprising a printed circuit board according to any one of claims 1 to 12, and a conductive layer disposed on at least one surface of the printed circuit board.

14. A method for manufacturing a printed circuit board according to any one of claims 1 to 13, The steps include forming a thermosetting composition and a mixture containing the plurality of coated boron nitride particles, The steps include: coating the reinforcing layer with the mixture, A method comprising the step of curing the thermosetting composition to form the printed circuit board.

15. The method according to claim 14, wherein the reinforcing layer comprises a plurality of glass fibers.

16. The method according to claim 15, further comprising the step of coating the reinforcing layer, first unfolding the reinforcing layer from a first roll, passing the reinforcing layer across the mixture, passing the reinforcing layer across a solvent-drying section to at least partially cure the thermosetting mixture, and winding the coated reinforcing layer onto a second roll to roll-to-roll coat the reinforcing layer with the mixture.

17. The method according to any one of claims 14 to 16, wherein the curing step includes a step of partially curing to form a prepreg.

18. The method according to any one of claims 14 to 17, further comprising the step of depositing a conductive layer on at least one surface of the printed circuit board.

19. The method according to any one of claims 14 to 18, further comprising the step of depositing the coating on the plurality of coated boron nitride particles by atomic layer deposition before forming the mixture.

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