Nonwoven prepregs, metal foil-clad boards, and printed circuit boards

Abstract

The present invention provides a nonwoven prepreg, a metal foil-clad laminate, and a printed circuit board. The nonwoven prepreg includes a fluorine-containing resin adhesive nonwoven fabric and a fluorine-containing resin composition. The fluorine-containing resin adhesive nonwoven fabric includes an adhesive that is a fluorine-containing resin emulsion and inorganic fibers. The fluorine-containing resin composition includes, by weight parts, 30 to 100 parts of a fluorine-containing resin emulsion and 0 to 70 parts of an inorganic filler. The nonwoven prepreg according to the present invention and the copper-clad laminate including the same have excellent dielectric properties and a low coefficient of thermal expansion, so that the copper-clad laminate can meet the requirements for the performance of copper-clad laminate materials in the high-frequency communication field.

Description

Technical Field

[0001] The present invention belongs to the technical field of communication materials, and specifically relates to non-woven prepregs, metal foil laminates, and printed circuit boards.

Background Art

[0002] As an important basic material in the fields of electronic communication and information industry, copper-clad laminates are widely applied in fields such as mobile phones, personal computers, vending machines, communication base stations, satellites, and wearable devices, pilotless vehicles, drones, and smart robots. Due to their excellent properties such as low dielectric loss, high thermal stability, and chemical stability, fluorine-containing resins represented by polytetrafluoroethylene (PTFE) are ideal base materials for manufacturing copper-clad laminates. Since the 1950s of the previous century, researchers have gradually improved the manufacturing process of PTFE-based copper-clad laminates by continuously optimizing the formulation and parameters.

[0003] Since fluorine-containing resins have high flexibility in the polymer chain, it is usually necessary to introduce inorganic materials to improve the mechanical strength of fluorine-containing resin-based copper-clad laminates. For example, CN104175686A discloses a method for manufacturing a PTFE composite dielectric substrate for microwave circuits. The method first mixes a fluororesin emulsion, an inorganic filler, and a thickener to obtain a stable and uniform dispersion liquid, and then applies the dispersion liquid to a moldable substrate, bakes it, separates the substrate from the resin layer after baking, overlaps the separated resin layer and copper foil, and laminates and sinters them at high temperature to obtain a double-sided copper foil-coated PTFE composite dielectric substrate. Here, the inorganic filler is preferably silica and / or titanium dioxide. CN101838431A discloses a fluororesin mixture and a copper-clad laminate manufactured using the same. The fluororesin mixture includes a polytetrafluoroethylene perfluoroalkyl vinyl ether emulsion, a polytetrafluoroethylene emulsion, an inorganic filler, and a diluent, and the inorganic filler is silicon fine powder, kaolin, or titanium white.

[0004] Because fluoropolymers have high polymer chain flexibility, glass cloth reinforcement is usually required to improve the mechanical strength of fluoropolymer copper-clad sheets. The braided structure of glass cloth in the warp and weft directions can cause non-uniformity of dielectric properties at different points in the copper-clad sheet. Furthermore, the use of glass cloth limits the addition of large amounts of inorganic fillers into the fluoropolymer substrate. For example, US4225180A discloses a method of obtaining a fluoropolymer-based copper-clad sheet that is not reinforced with glass cloth by sequentially mixing microfibers and inorganic fillers into a PTFE emulsion, and then obtaining a fluoropolymer mixture through steps such as filtration and drying, and pressing it into a sheet material.

[0005] Therefore, developing copper-clad sheets that possess excellent dielectric properties, thermal expansion coefficient, and mechanical strength is an urgent issue that needs to be addressed in this field. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] To address the shortcomings of the prior art, the present invention aims to provide a nonwoven fabric prepreg, a metal foil-clad board, and a printed circuit board. The prepreg comprises a fluorine-containing resin adhesive nonwoven fabric and a fluorine-containing resin composition, and the copper-clad board produced from the nonwoven fabric prepreg has excellent dielectric properties, thermal expansion coefficient, and mechanical strength. [Means for solving the problem]

[0007] To achieve this objective, the present invention employs the following technical solutions. In one aspect, the present invention provides a nonwoven fabric prepreg comprising a fluorine-containing resin adhesive nonwoven fabric and a fluorine-containing resin composition, wherein the fluorine-containing resin adhesive nonwoven fabric comprises an adhesive which is a fluorine-containing resin emulsion and inorganic fibers, and the fluorine-containing resin composition comprises 30 to 100 parts by weight of fluorine-containing resin emulsion and 10 to 70 parts by weight of inorganic filler.

[0008] This invention allows for the production of low dielectric loss high-frequency copper-clad sheets by using a fluorine-containing resin emulsion adhesive. The nonwoven fabric has low dielectric loss, good uniformity, consistent thickness, consistent fiber anisotropy distribution, and high tensile strength. A large amount of dielectric filler can be added when immersing the sheet in the low dielectric loss resin. Copper-clad sheets obtained from a prepreg by compounding a nonwoven fabric produced with an adhesive containing a fluorine-containing resin emulsion with a fluorine-containing resin emulsion and an inorganic filler have excellent dielectric properties, thermal expansion coefficient, and mechanical strength.

[0009] In the present invention, the fluorine-containing resin composition comprises 30 to 100 parts by weight of fluorine-containing resin emulsion, for example, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 68, 70, 72, 74, 80, 86, 88, 90, 94, 96, 98, 100, and so on.

[0010] The fluorine-containing resin composition contains 10 to 70 parts by weight of inorganic filler, for example, 10, 16, 18, 20, 24, 26, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, etc.

[0011] In the present invention, the fluorine-containing resin emulsion in the adhesive and the fluorine-containing resin emulsion in the fluorine-containing resin composition are each independently one or at least two selected from polytetrafluoroethylene emulsion, polyperfluoroethylene propylene emulsion, polyvinylidene fluoride emulsion, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer emulsion, ethylene-tetrafluoroethylene copolymer emulsion, polychlorotrifluoroethylene emulsion, or ethylene-chlorotrifluoroethylene copolymer emulsion.

[0012] Preferably, the weight percentage of inorganic fibers in the fluorine-containing resin adhesive nonwoven fabric is 60-95% (e.g., 60%, 62%, 65%, 68%, 70%, 73%, 75%, 78%, 80%, 83%, 85%, 88%, 90%, 93%, or 95%), and the weight percentage of adhesive is 5-40% (e.g., 5%, 8%, 10%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 33%, 35%, 38%, or 40%). In this invention, if the weight percentage of adhesive is too low, the adhesive cannot form a continuous film, resulting in low strength of the nonwoven fabric. If the weight percentage of adhesive is too high, there will be many voids inside the nonwoven fabric, resulting in many defects, low strength of the nonwoven fabric, and further affecting dielectric loss and tackiness.

[0013] Preferably, the solid content of the fluorine-containing resin emulsion is 30-70%, for example, 30%, 35%, 38%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%.

[0014] Preferably, the particle size of the fluorine-containing resin in the fluorine-containing resin emulsion is 0.10 μm to 0.40 μm, for example, 0.10 μm, 0.15 μm, 0.20 μm, 0.25 μm, 0.30 μm, 0.35 μm, or 0.40 μm.

[0015] In this specification, the particle size of the fluorine-containing resin emulsion is measured by laser diffraction, using a Malvern MS3000 laser particle size analyzer. In this specification, the dielectric constant and dielectric loss are measured according to the SPDR (split post dielectric resonator) method, under A-state conditions and a frequency of 10 GHz.

[0016] Preferably, the inorganic fiber is one or at least two selected from E glass fiber, NE glass fiber, L glass fiber, quartz fiber, alumina fiber, boron nitride fiber, silicon carbide fiber, zinc oxide fiber, magnesium oxide fiber, silicon nitride fiber, boron carbide fiber, aluminum nitride fiber, alumina whisker, boron nitride whisker, silicon carbide whisker, zinc oxide whisker, magnesium oxide whisker, silicon nitride whisker, boron carbide whisker, or aluminum nitride whisker.

[0017] Preferably, the average diameter of the inorganic fibers is less than 13 micrometers, for example, 12 micrometers, 10 micrometers, 9 micrometers, 8 micrometers, 7 micrometers, 6 micrometers, 5 micrometers, 4 micrometers, 3 micrometers, 2 micrometers, 1 micrometer, or 0.5 micrometers, and is preferably less than 10 micrometers, and preferably between 0.5 and 5 micrometers.

[0018] Preferably, the average length of the inorganic fibers is 1 to 100 millimeters, for example, 2 millimeters, 5 millimeters, 8 millimeters, 10 millimeters, 30 millimeters, 50 millimeters, 80 millimeters, or 100 millimeters, with 1 to 10 millimeters being preferred. The average diameter and average length of the inorganic fibers in this invention are both obtained by observation and measurement using a scanning electron microscope.

[0019] Preferably, the adhesive can be dissolved and diluted to an appropriate viscosity by adding a solvent as needed, thereby ensuring uniform dispersion of fibers and adhesive in the manufactured nonwoven fabric. The solvent may include, for example, deionized water. The solvent will volatilize during oven drying and sintering in the manufacturing process of the nonwoven fabric.

[0020] Preferably, the adhesive further comprises a dispersant, a thickener, an antifoaming agent, and the like. Preferably, the method for producing the fluorine-containing resin adhesive nonwoven fabric involves mixing inorganic fibers with an adhesive, immersing them, forming them by papermaking, drying them in an oven, and sintering them to obtain the fluorine-containing resin adhesive nonwoven fabric.

[0021] Preferably, the immersion time is 40 to 50 minutes, for example, 40 minutes, 43 minutes, 45 minutes, 48 ​​minutes, or 50 minutes.

[0022] Preferably, the oven drying temperature is 120-150°C, for example 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, or 150°C, and the time is 1-30 min, for example 1 min, 3 min, 5 min, 8 min, 10 min, 13 min, 15 min, 18 min, or 20 min.

[0023] Preferably, the sintering temperature is 250°C to 350°C, for example 250°C, 270°C, 290°C, 300°C, 320°C, 340°C, or 350°C, and the sintering time is 1 to 20 mins, for example 1 min, 3 mins, 5 mins, 8 mins, 10 mins, 13 mins, 15 mins, 18 mins, or 20 mins.

[0024] Preferably, the unit weight (also called the unit area mass) of the fluorine-containing resin adhesive nonwoven fabric is 20-200 grams / square meter, for example, 20 grams / square meter, 25 grams / square meter, 30 grams / square meter, 35 grams / square meter, 40 grams / square meter, 50 grams / square meter, 60 grams / square meter, 80 grams / square meter, 100 grams / square meter, 120 grams / square meter, 150 grams / square meter, 180 grams / square meter, or 200 grams / square meter, with 20-100 grams / square meter being preferred. By adjusting the amount of inorganic fibers, adhesive, solvent added and the vehicle speed, fluorine-containing resin adhesive nonwoven fabrics with different unit weights can be obtained.

[0025] Preferably, the inorganic filler includes any one or at least a combination of two or more of spherical titania, angular titania, spherical silica, hollow silica, barium titanate, strontium titanate, chopped glass fiber, alumina, boron nitride, silicon nitride, alumina whisker, boron nitride whisker or hollow glass beads. The inorganic filler can be selected as needed. For example, a high-DK filler is selected for a high-DK board material, and a thermal conductivity filler is added to a thermal conductivity board material, and so on.

[0026] In the present invention, prepregs manufactured by combining a fluorine-containing resin emulsion with different fillers can meet different dielectric needs and thermal conductivity needs, for example, as follows.

[0027] The fluorine-containing resin composition contains, in parts by solid weight, 30 to 50 parts of a fluorine-containing resin, 25 to 35 parts of titania, and 10 to 20 parts of silica, and a circuit board with a Dk of 6 ± 0.5 can be manufactured using the same. Here, the fluorine-containing resin in parts by solid weight refers to the content of the fluorine-containing resin portion obtained by removing the solvent from the fluorine-containing resin emulsion, and can be obtained by multiplying the weight of the fluorine-containing resin emulsion by the solid content of the fluorine-containing resin emulsion.

[0028] The fluorine-containing resin composition contains, in parts by solid weight, 30 to 40 parts of a fluorine-containing resin, 55 to 70 parts of titania, and 5 to 20 parts of silica, and a circuit board with a Dk of 10 ± 0.5 can be manufactured using the same.

[0029] The fluorine-containing resin composition contains, in parts by solid weight, 30 to 60 parts of a fluorine-containing resin, 20 to 40 parts of boron nitride, 4 to 10 parts of titania, and 10 to 20 parts of silica, and a circuit board with a Dk of 3.5 ± 0.5 and a thermal conductivity exceeding 1.44 W / mk can be manufactured using the same.

[0030] The fluorine-containing resin composition comprises 40 to 60 parts by solid weight of fluorine-containing resin, 0 to 10 parts of titania, and 40 to 60 parts of silica, and a circuit board with a Dk of 3 ± 0.5 can be manufactured using this composition.

[0031] A preferred technical application of the present invention is a surface-modified inorganic filler. Copper-clad sheets obtained by surface modification using reagents have superior dielectric properties and a lower coefficient of thermal expansion.

[0032] Preferably, the surface modifier used for the surface modification is a silane coupling agent. Preferably, the silane coupling agent includes one or at least two of the following: a fluorine-containing silane coupling agent, an aminosilane coupling agent, an epoxysilane coupling agent, a vinylsilane coupling agent, or an acrylicsilane coupling agent.

[0033] Preferably, the amount of the surface modifier is 0.05 to 0.5% of the mass of the inorganic filler to be surface-treated, and may be, for example, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc.

[0034] Exemplary, the fluorine-containing resin composition is produced by a method comprising mixing a fluorine-containing resin emulsion and an inorganic filler, then uniformly dispersing them to obtain the fluorine-containing resin composition.

[0035] During the manufacturing process, thickeners, dispersants, or solvents may be further added to the fluorine-containing resin composition. The amount of these additives should be selected by those skilled in the art according to their experience and process needs, and should be such that an appropriate viscosity is obtained to facilitate the immersion, coating, and use of the fluorine-containing resin composition. During the drying, sintering, and other stages described later, the thickeners and other auxiliary agents may partially or completely volatilize.

[0036] Preferably, the nonwoven fabric prepreg is manufactured by immersing the fluorine-containing resin adhesive nonwoven fabric in the fluorine-containing resin composition, drying and / or sintering it.

[0037] Preferably, the drying temperature is 100 to 260°C, and may be, for example, 110°C, 130°C, 150°C, 170°C, 190°C, 200°C, 210°C, 230°C, or 250°C.

[0038] Preferably, the drying time is 10 to 120 minutes, and may be, for example, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, or 110 minutes.

[0039] Preferably, the sintering temperature is 200 to 400°C, and may be, for example, 210°C, 230°C, 250°C, 270°C, 290°C, 300°C, 310°C, 330°C, 350°C, 370°C, or 390°C.

[0040] Preferably, the sintering time is 0.1 to 12 hours, and may be, for example, 0.2 hours, 0.25 hours, 0.5 hours, 0.75 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or 11 hours.

[0041] Preferably, the sintering is carried out in an inert gas atmosphere. Preferably, the inert gas atmosphere includes a nitrogen gas atmosphere and / or an argon gas atmosphere.

[0042] In another aspect, the present invention provides a metal foil-clad sheet comprising a metal foil and the aforementioned nonwoven fabric prepreg.

[0043] Preferably, the metal foil is copper foil. In this case, the metal foil-clad plate is a copper-clad plate.

[0044] In another aspect, the present invention provides a printed circuit board comprising at least one of the nonwoven fabric prepreg or metal foil-clad board described above.

[0045] Preferably, the printed circuit board is a high-frequency printed circuit board. In this invention, "high frequency" is defined as having a frequency of 1 GHz or higher. [Effects of the Invention]

[0046] Compared to the prior art, the present invention has the following beneficial effects. The nonwoven fabric prepreg according to the present invention is obtained by compounding a fluorine-containing resin composition with a fluorine-containing resin adhesive nonwoven fabric with low dielectric loss. As a result, the nonwoven fabric prepreg and the copper-clad sheet containing it have excellent dielectric properties, with a dielectric constant of 2.2 to 11 at 10 GHz, a dielectric loss of less than 0.003, and a low coefficient of thermal expansion. Therefore, the copper-clad sheet can meet the performance requirements for copper-clad sheet materials in the high-frequency communication field. [Modes for carrying out the invention]

[0047] The technical aspects of the present invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the above embodiments are merely for the purpose of understanding the present invention and should not be considered as specifically limiting the present invention.

[0048] The experimental materials and apparatus used in the examples and comparative examples of the present invention are as follows. (1) Fluorine-containing resin composition A-1: ​​64 parts by weight of polytetrafluoroethylene emulsion (PTFE emulsion, particle size 0.25 μm, solid content 55%, D210C manufactured by Nippon Daikin Co., Ltd.), 10 parts by weight of FEP resin emulsion (solid content 50 wt%, manufactured by Nippon Daikin Co., Ltd., model number: ND-110), 3 parts of titania (average particle size 10 μm, purchased from WuXi Noble Electronics Co., Ltd., silane A171 surface treatment), and 60 parts of silica (average particle size 10 μm, purchased from JiangSu NOVORAY) are stirred and mixed for 2 hours to obtain fluorine-containing resin composition A-1.

[0049] Fluorine-containing resin composition A-2: 58.5 parts by weight of polytetrafluoroethylene emulsion (PTFE emulsion, particle size 0.25 μm, solid content 55%, D210C manufactured by Nippon Daikin Co., Ltd.), 32.5 parts of titania (average particle size 10 μm, purchased from WuXi Noble Electronics Co., Ltd.), and 17 parts of silica (average particle size 10 μm, purchased from JiangSu NOVORAY) are stirred and mixed for 2 hours to obtain fluorine-containing resin composition A-2.

[0050] Fluorine-containing resin composition A-3: 55 parts by weight of polytetrafluoroethylene emulsion (PTFE emulsion, particle size 0.25 μm, solid content 55%, D210C manufactured by Nippon Daikin Co., Ltd.), 65 parts of titania (average particle size 10 μm, purchased from WuXi Noble Electronics Co., Ltd.), and 18.5 parts of silica (average particle size 10 μm, purchased from JiangSu NOVORAY, treated with silane KBM-503) are stirred and mixed for 2 hours to obtain fluorine-containing resin composition A-3.

[0051] Fluorine-containing resin composition A-4: 60 parts by weight of polytetrafluoroethylene emulsion (PTFE emulsion, particle size 0.25 μm, solid content 55%, D210C manufactured by Nippon Daikin Co., Ltd.), 24 parts of boron nitride (average particle size 10 μm, purchased from AnHui Estone), 6 parts of titania (average particle size 10 μm, purchased from WuXi Noble Electronics Co., Ltd.), and 18 parts of silica (average particle size 10 μm, purchased from JiangSu NOVORAY, treated with silane KBM-12) are stirred and mixed for 2 hours to obtain fluorine-containing resin composition A-4.

[0052] (2) The specific manufacturing method for low dielectric loss nonwoven fabric includes the following steps: Glass fibers and a fluorine-containing emulsion were immersed for 45 minutes and then formed by papermaking. After drying in a 150°C oven, the material was sintered for 10 minutes in a 320°C high-temperature oven. After removal and cooling, low dielectric loss nonwoven fabrics with different unit weights were produced. The amounts of glass fibers, fluorine-containing emulsion, and adhesive, and the corresponding nonwoven fabric types are as follows:

[0053] Low dielectric loss nonwoven fabric B-1: E glass fibers with an average diameter of 8 μm (JUSHI China), FEP resin adhesive (solids content 50 wt%, manufactured by Nippon Daikin Co., Ltd., model number: ND-110), adhesive content 10%, nonwoven fabric unit weight 75 grams / square meter.

[0054] Low dielectric loss nonwoven fabric B-2: NE glass fibers with an average diameter of 5 μm (JUSHI China), PFA resin adhesive (solid content 55 wt%, manufactured by Nippon Daikin Co., Ltd., model number: AD-2CR), adhesive content 20%, nonwoven fabric unit weight 75 grams / square meter.

[0055] Low dielectric loss nonwoven fabric B-3: Quartz glass fibers with an average diameter of 0.5 μm and 5 μm (ShenJiu China), PTFE resin adhesive (solids content 55 wt%, manufactured by Nippon Daikin Co., Ltd., model number: D210C), adhesive content 20%, nonwoven fabric unit weight 25 grams / square meter.

[0056] (3) Other reinforcing materials General nonwoven fabric B-4: E glass fibers with an average diameter of 12 μm, epoxy resin adhesive, manufactured by Shaanxi Huatek, nonwoven fabric unit weight 75 grams / square meter.

[0057] Nonwoven fabric B-5 differs from low dielectric loss nonwoven fabric B-1 in that it contains 50% adhesive.

[0058] Nonwoven fabric B-6: Made from acrylate adhesive and E glass fibers with an average diameter of 13 μm, manufactured by Shaanxi Huatek, with a unit weight of 75 grams / square meter. E glass cloth: E glass fiber, model 106, manufactured by Asahi Schwebel Co., Ltd. [Examples]

[0059] (1) The fluorine-containing resin composition A-1 was immersed in nonwoven fabric B-1, dried in an oven at 100°C for 1 hour, and sintered in an oven at 360°C for 0.5 hours to obtain a fluorine-containing resin nonwoven fabric prepreg with a thickness of 380 μm.

[0060] (2) Two fluorine-containing resin nonwoven fabric prepregs were laminated together to form a sheet with dimensions of 250 mm x 250 mm. The laminated prepreg layers were coated with 1 oz thick copper foil on both the upper and lower surfaces, the applied pressure was approximately 400 PSI, the maximum temperature was 380°C, and the holding time was 90 min. The lamination process yielded the copper-clad sheet. [Examples]

[0061] (1) The fluorine-containing resin composition A-1 was immersed in nonwoven fabric B-2, dried in an oven at 100°C for 1 hour, and sintered in an oven at 360°C for 0.5 hours to obtain a fluorine-containing resin nonwoven fabric prepreg with a thickness of 380 μm.

[0062] (2) Two fluorine-containing resin nonwoven fabric prepregs were laminated together to form a sheet with dimensions of 250 mm x 250 mm. The laminated resin layers were coated with copper foil with a thickness of 1 oz on both the upper and lower surfaces, the applied pressure was approximately 400 PSI, the maximum temperature was 380°C, and the holding time was 90 min. The lamination process yielded the copper-clad sheet. [Examples]

[0063] (1) Nonwoven fabric B-3 was immersed in fluorine-containing resin composition A-2, dried in an oven at 100°C for 1 hour, and sintered in an oven at 360°C for 0.5 hours to obtain a fluorine-containing resin nonwoven fabric prepreg with a thickness of 127 μm.

[0064] (2) Two fluorine-containing resin nonwoven fabric prepregs were laminated together to form a sheet with dimensions of 250 mm x 250 mm. The laminated resin layers were coated with copper foil with a thickness of 1 oz on both the upper and lower surfaces, the applied pressure was approximately 400 PSI, the maximum temperature was 380°C, and the holding time was 90 min. The lamination process yielded the copper-clad sheet. [Examples]

[0065] (1) The fluorine-containing resin composition A-3 was immersed in nonwoven fabric B-3, dried in an oven at 100°C for 1 hour, and sintered in an oven at 360°C for 0.5 hours to obtain a fluorine-containing resin nonwoven fabric prepreg with a thickness of 127 μm.

[0066] (2) Two fluorine-containing resin nonwoven fabric prepregs were laminated together to form a sheet with dimensions of 250 mm x 250 mm. The laminated resin layers were coated with copper foil with a thickness of 1 oz on both the upper and lower surfaces, the applied pressure was approximately 400 PSI, the maximum temperature was 380°C, and the holding time was 90 min. The lamination process yielded the copper-clad sheet. [Examples]

[0067] (1) Nonwoven fabric B-3 was immersed in fluorine-containing resin composition A-4, dried in an oven at 100°C for 1 hour, and sintered in an oven at 360°C for 0.5 hours to obtain a fluorine-containing resin nonwoven fabric prepreg with a thickness of 127 μm.

[0068] (2) Two fluorine-containing resin nonwoven fabric prepregs were laminated together to form a sheet with dimensions of 250 mm x 250 mm. The laminated resin layers were coated with copper foil with a thickness of 1 oz on both the upper and lower surfaces, the applied pressure was approximately 400 PSI, the maximum temperature was 380°C, and the holding time was 90 min. The lamination process yielded the copper-clad sheet.

[0069] [Comparative Example 1] (1) The fluorine-containing resin composition A-1 was immersed in nonwoven fabric B-4, dried in an oven at 100°C for 1 hour, and sintered in an oven at 360°C for 0.5 hours to obtain a fluorine-containing resin nonwoven fabric prepreg with a thickness of 380 μm.

[0070] (2) Two fluorine-containing resin nonwoven fabric prepregs were laminated together to form a sheet with dimensions of 250 mm x 250 mm. The laminated resin layers were coated with copper foil with a thickness of 1 oz on both the upper and lower surfaces, the applied pressure was approximately 400 PSI, the maximum temperature was 380°C, and the holding time was 90 min. The lamination process yielded the copper-clad sheet.

[0071] [Comparative Example 2] (1) The fluorine-containing resin composition A-1 was immersed in nonwoven fabric B-5, dried in an oven at 100°C for 1 hour, and sintered in an oven at 360°C for 0.5 hours to obtain a fluorine-containing resin nonwoven fabric prepreg with a thickness of 380 μm.

[0072] (2) Two fluorine-containing resin nonwoven fabric prepregs were laminated together to form a sheet with dimensions of 250 mm x 250 mm. The laminated resin layers were coated with copper foil with a thickness of 1 oz on both the upper and lower surfaces, the applied pressure was approximately 400 PSI, the maximum temperature was 380°C, and the holding time was 90 min. The lamination process yielded the copper-clad sheet.

[0073] [Comparative Example 3] This method differs from Example 1 only in that nonwoven fabric B-6 is used to replace nonwoven fabric B-1.

[0074] [Comparative Example 4] (1) A fluorine-containing resin composition A-1 was immersed in a 106-type E glass cloth, dried in an oven at 100°C for 1 hour, and sintered in an oven at 360°C for 0.5 hours to obtain a fluorine-containing resin nonwoven fabric prepreg with a thickness of 100 μm.

[0075] (2) Two fluorine-containing resin nonwoven fabric prepregs were laminated together to form a sheet with dimensions of 250 mm x 250 mm. The laminated resin layers were coated with copper foil with a thickness of 1 oz on both the upper and lower surfaces, the applied pressure was approximately 400 PSI, the maximum temperature was 380°C, and the holding time was 90 min. The lamination process yielded the copper-clad sheet.

[0076] [Comparative Example 5] (1) The fluorine-containing resin composition A-2 was immersed in nonwoven fabric B-4, dried in an oven at 100°C for 1 hour, and sintered in an oven at 360°C for 0.5 hours to obtain a fluorine-containing resin nonwoven fabric prepreg with a thickness of 127 μm.

[0077] (2) Two fluorine-containing resin nonwoven fabric prepregs were laminated together to form a sheet with dimensions of 250 mm x 250 mm. The laminated resin layers were coated with copper foil with a thickness of 1 oz on both the upper and lower surfaces, the applied pressure was approximately 400 PSI, the maximum temperature was 380°C, and the holding time was 90 min. The lamination process yielded the copper-clad sheet.

[0078] Performance measurement The copper-clad plates manufactured in the above-described examples and comparative examples were subjected to the following performance measurements.

[0079] (1) Measurement of Dk and Df: Measurements were taken according to the SPDR (split post dielectric resonator) method. The measurement conditions were A-state and a frequency of 10 GHz.

[0080] (2) Coefficient of thermal expansion (X / Y): The coefficient of thermal expansion of the material in the X / Y direction and in the temperature range of -55 to 288°C was measured using IPC-TM-650 2.4.24.

[0081] The specific measurement results are shown in Table 1.

[0082] [Table 1]

[0083] As can be seen from the table above, the nonwoven fabric prepreg according to the present invention is obtained by immersing a fluorine-containing resin composition in a fluorine-containing resin adhesive nonwoven fabric. The copper-clad sheet containing the nonwoven fabric prepreg has excellent dielectric properties and a low coefficient of thermal expansion, and can meet the performance requirements for copper-clad sheet materials in the high-frequency communication field.

[0084] As can be seen from Examples 1 to 5, the copper-clad sheets containing the nonwoven fabric prepreg have a dielectric constant between 3.06 and 10.35, a dielectric loss of less than 0.003, and a thermal expansion coefficient of less than 50 ppm. Both the dielectric loss and thermal expansion coefficient are clearly superior to those of copper-clad sheets made from general nonwoven fabrics and glass fiber woven fabrics. Furthermore, as can be seen from Comparative Examples 1, 3, and 5, when using a general nonwoven fabric prepreg, the dielectric loss of the sheet material improved slightly, and the thermal expansion coefficient increased. In Comparative Example 4, when using a general E-glass cloth prepreg, the dielectric loss of the sheet material increased further, and the difference in the thermal expansion coefficient in the X / Y direction became larger due to the braided structure of the glass cloth.

[0085] In Comparative Example 2, the amount of fluorine-containing resin adhesive in the nonwoven fabric was too high, resulting in many voids in the copper-clad plate. Compared to Example 1, the dielectric constant of the plate material was slightly lower, but the dielectric loss was clearly higher, and the coefficient of thermal expansion was higher.

[0086] In short, the fluorine-containing resin adhesive nonwoven fabric prepreg according to the present invention allows copper-clad plates containing the nonwoven fabric prepreg to possess excellent dielectric properties and a low coefficient of thermal expansion, making them applicable to the field of high-frequency communications.

[0087] Although the present invention has described the nonwoven fabric prepreg, metal foil-clad board, and printed circuit board of the present invention with respect to the above embodiments, the applicant declares that the present invention is not limited to the above embodiments, that is, the present invention does not have to be carried out in accordance with the above embodiments. It will be clear to those skilled in the art that any improvements to the present invention, equivalent substitutions of each raw material in the products of the present invention, addition of auxiliary components, selection of specific embodiments, etc., all fall within the scope of protection and disclosure of the present invention.

Claims

1. A nonwoven fabric prepreg comprising a fluorine-containing resin adhesive nonwoven fabric and a fluorine-containing resin composition, The aforementioned fluorine-containing resin adhesive nonwoven fabric comprises an adhesive which is a fluorine-containing resin emulsion and inorganic fibers. The fluorine-containing resin composition comprises, by weight, 30 to 100 parts by weight of fluorine-containing resin emulsion and 10 to 70 parts by weight of inorganic filler. In the aforementioned fluorine-containing resin adhesive nonwoven fabric, the weight percentage of inorganic fibers is 60-95%, and the weight percentage of adhesive is 5-40%. A nonwoven fabric prepreg characterized by the following features.

2. The fluorine-containing resin emulsion is one or at least two selected from polytetrafluoroethylene emulsion, polyperfluoroethylene propylene emulsion, polyvinylidene fluoride emulsion, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer emulsion, ethylene-tetrafluoroethylene copolymer emulsion, polychlorotrifluoroethylene emulsion, or ethylene-chlorotrifluoroethylene copolymer emulsion. The nonwoven fabric prepreg according to feature 1.

3. The inorganic fiber is one or at least two selected from E glass fiber, NE glass fiber, L glass fiber, quartz fiber, alumina fiber, boron nitride fiber, silicon carbide fiber, zinc oxide fiber, magnesium oxide fiber, silicon nitride fiber, boron carbide fiber, aluminum nitride fiber, alumina whisker, boron nitride whisker, silicon carbide whisker, zinc oxide whisker, magnesium oxide whisker, silicon nitride whisker, boron carbide whisker, or aluminum nitride whisker. The nonwoven fabric prepreg according to feature 1.

4. The average diameter of the inorganic fibers is less than 13 micrometers. The nonwoven fabric prepreg according to feature 1.

5. The average length of the inorganic fibers is 1 to 100 millimeters. The nonwoven fabric prepreg according to feature 1.

6. The inorganic filler includes one or at least two of the following: spherical titania, angular titania, spherical silica, hollow silica, barium titanate, strontium titanate, chopped glass fibers, alumina, boron nitride, silicon nitride, alumina whiskers, boron nitride whiskers, or hollow glass beads. The nonwoven fabric prepreg according to feature 1.

7. The unit weight of the fluorine-containing resin adhesive nonwoven fabric is 20 to 200 grams / square meter. The nonwoven fabric prepreg according to feature 1.

8. The fluorine-containing resin composition comprises, by solid weight, 30 to 50 parts fluorine-containing resin, 25 to 35 parts titania, and 10 to 20 parts silica. The nonwoven fabric prepreg according to feature 1.

9. The fluorine-containing resin composition comprises, by solid weight, 30 to 40 parts fluorine-containing resin, 55 to 70 parts titania, and 5 to 20 parts silica. The nonwoven fabric prepreg according to feature 1.

10. The fluorine-containing resin composition comprises, by solid weight, 30 to 60 parts fluorine-containing resin, 20 to 40 parts boron nitride, 4 to 10 parts titania, and 10 to 20 parts silica. The nonwoven fabric prepreg according to feature 1.

11. The fluorine-containing resin composition comprises, by solid weight, 40 to 60 parts fluorine-containing resin, 0 to 10 parts titania, and 40 to 60 parts silica. The nonwoven fabric prepreg according to feature 1.

12. The nonwoven fabric prepreg is obtained by immersing the fluorine-containing resin adhesive nonwoven fabric in the fluorine-containing resin composition, drying it, and sintering it. The nonwoven fabric prepreg according to feature 1.

13. A metal foil and a nonwoven fabric prepreg as described in claim 1, Metal foil clad board.

14. The nonwoven fabric prepreg described in any one of claims 1 to 12 or the metal foil-clad board described in claim 13 comprises at least one of these. Printed circuit board.

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