Composite films for mobile electronic device components

Abstract

The present disclosure relates to a composite film exhibiting a thickness of less than 0.10 mm, produced from at least one fluoropolymer and a fiber fabric, and to an article comprising such a composite film, exhibiting low dielectric constant and dissipation factor, and suitable for portable electronic device components, such as a flexible printed circuit board (FPC).

Description

[Technical field]

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 209427, filed June 11, 2021, and European Patent Application Publication No. 21195291.6, filed September 7, 2021, the entire contents of each of which are incorporated herein by reference for all purposes.

[0002] The present disclosure relates to a composite film comprising at least one fluoropolymer and at least one fiber fabric, exhibiting a thickness of less than 0.10 mm. Such composite films are flexible due to their thickness and exhibit low dielectric constants and dissipation factors, making them suitable for portable electronic device components, such as copper clad laminates (CCLs) and flexible printed circuits (FPCs). [Background technology]

[0003] Due to their reduced weight and high mechanical performance, polymer compositions are widely used to manufacture portable electronic device components. Currently, there is a high market demand for polymer compositions that can be used to manufacture portable electronic device components with improved dielectric performance (i.e., low dielectric constant and loss tangent).

[0004] In portable electronic devices, the materials forming the various components and housings can significantly impair wireless radio signals (e.g., frequencies of 1 MHz, 2.4 GHz, and 5.0 GHz) transmitted and received by the portable electronic device through one or more antennas. The dielectric performance of materials used in portable electronic devices can be determined by measuring the dielectric constant and dissipation factor, which describe the ability of a material to interact with electromagnetic radiation and disrupt electromagnetic signals (e.g., radio signals) traveling through the material. Thus, the lower the dielectric constant of a material at a given frequency, the less the material will disrupt electromagnetic signals at that frequency.

[0005] Polymer films are used in the field of portable electronic devices. For example, aromatic polyimide films in the form of continuous aromatic polyimide film / copper foil laminate structures have been described for the production of flexible printed circuit boards (FPCs), carrier tapes for tape automated bonding (TAB), and tapes for lead-on-chip (LOC) structures. Such films have been shown to exhibit excellent high temperature resistance, excellent chemical properties, high electrical insulation, and high mechanical strength. However, polyimide films do not exhibit the expected dielectric performance, in particular the dielectric loss tangent of polyimide films is too high to be used for applications at high frequencies (≧20 GHz). In addition, the dielectric loss tangent of polyimide films at high frequencies is further deteriorated in humid environments due to moisture absorption.

[0006] It is an object of the present invention to provide a composite film having improved dielectric performance, the composite film being made from a fluoropolymer and a fibrous substrate.

[0007] U.S. Patent No. 8,741,790 relates to PTFE / fiberglass composites useful as conveyor belts. Conveyor belts made from PTFE resins are used in many different applications. Many of these applications rely on heat being transferred through the belt, so it is preferable to keep the thickness of the belt to a minimum. As described in this document, thicknesses typically range from a minimum of 5 mils (i.e., 0.127 mm) to, in some cases, a maximum of 20 mils (i.e., 0.508 mm).

[0008] However, the films described in this document are not suitable for portable electronic device components such as copper clad laminates (CCLs) and flexible printed circuits (FPCs).

[0009] WO 2007 / 024837 A2 discloses a composite structure comprising a glass cloth and a melt-processable fluoropolymer, the entire thickness of the glass cloth being embedded in the fluoropolymer, said fluoropolymer containing an effective amount of adhesive to improve adhesion to the copper layer of the composite structure. WO 2007 / 024837 A2 does not disclose the dielectric properties of the glass cloth used in the composite structure.

[0010] EP 3489299A1 discloses a method for producing a film or laminate using a liquid composition containing a liquid medium and a resin powder dispersed in the liquid medium, characterized in that the resin powder has an average particle size of 0.3 to 6 μm, a cumulative 90% diameter based on volume of the resin powder is up to 8 μm, and the resin powder is a resin containing a fluorinated copolymer containing a unit containing a functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group, and an isocyanate group. EP 3489299A1 does not disclose a method for obtaining a film or laminate using a dry powder of a fluorinated polymer.

[0011] JP2020083990A discloses a method for producing a composite material, which includes impregnating an amino group-introduced spread glass cloth with a dispersion obtained by dispersing a powder containing an oxygen atom-containing tetrafluoroethylene-based polymer in a solvent; heating the dispersion; and fixing the tetrafluoroethylene-based polymer to the glass cloth. The amino group-introduced spread glass cloth is preferably obtained by contact-treating the spread glass cloth with a silane coupling agent having an amino group, or by plasma-treating the spread glass cloth in a nitrogen-containing atmosphere. JP2020083990A does not disclose a method for obtaining a composite material using a dry powder of a polymer that is a tetrafluoroethylene-based polymer. Summary of the Invention

[0012] The present invention relates to a composite film exhibiting a thickness of less than 0.10 mm, at least one fluoropolymer [polymer (FP)] comprising repeat units derived from tetrafluoroethylene, and - At least one textile fabric [Textile Fabric (F)] The present invention relates to a composite film comprising:

[0013] In a preferred embodiment, the composite film comprises a fiberglass fabric that is a low dielectric constant, low dissipation factor fiberglass fabric.

[0014] The present invention also relates to a method for producing such a composite film.

[0015] Other objects of the present invention are: an article or component comprising at least one composite film of the present invention, the use of at least one such composite film for producing a portable electronic device article or component, such as a flexible printed circuit board (FPC), and the use of a powder of a polymer (FP) as defined above for producing a composite film having a thickness of less than 0.10 mm, said polymer (FP) comprising repeat units derived from tetrafluoroethylene and said composite film further comprising at least one fiber fabric (F). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] In this application: - any description, even if made in relation to a particular embodiment, is applicable and interchangeable with other embodiments of the invention; - when an element or component is said to be included in and / or selected from a list of enumerated elements or components, in the relevant embodiments expressly contemplated herein, it is to be understood that the element or component may be any one of the individual enumerated elements or components, or may also be selected from the group consisting of any two or more of the explicitly enumerated elements or components, and that any element or component enumerated in a list of elements or components may be omitted from such list; - any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited range, as well as the endpoints of the range, and equivalents thereof; and - the term "and / or" used in a phrase of the form "A and / or B" means A only, B only, or A and B together.

[0017] Composite Film The present invention relates to a composite film exhibiting a thickness of less than 0.10 mm, at least one fluoropolymer (hereinafter polymer (FP)) comprising repeat units derived from tetrafluoroethylene, and - at least one textile fabric (hereafter referred to as textile fabric (F)) The present invention relates to a composite film comprising:

[0018] The composite films of the present invention are characterized by their flexibility compared to commercially available films. Due to their thinness and the chemical nature of the resins used in the manufacture of the films, combined with the fiber substrate, the films of the present invention not only exhibit suitable flexibility for portable electronic device components, but also a suitable set of mechanical properties, such as tensile strength and coefficient of thermal expansion. The composite films of the present invention are also advantageously characterized by excellent dielectric properties for use in portable electronic device components. In particular, they are characterized by a low dielectric constant and a low dielectric loss tangent even at high frequencies.

[0019] The composite film has a thickness comprised between 0.10 mm and 0.005 mm, preferably between 0.09 and 0.01 mm, for example between 0.08 and 0.02 or between 0.07 and 0.03 mm. The thickness of the composite film can be measured by any means. For example, it can be measured using a thickness gauge. The inventors have recognized that such thicknesses are technically relevant. A composite film having a claimed thickness maintains its shape thanks to the fiber fabric while at the same time maintaining the bendability required for the application. Due to this combination of properties, the film of the present invention is well suited for use as a portable electronic device component, such as a copper clad laminate (CCL) or a flexible printed circuit board (FPC).

[0020] The polymer (FP) used in the composite film of the present invention contains repeat units derived from tetrafluoroethylene (TFE).

[0021] In some embodiments, the polymer (FP) used in the composite films of the present invention is polytetrafluoroethylene (PTFE), which offers excellent chemical resistance, high temperature capability, and excellent release properties.

[0022] For purposes of this invention, polytetrafluoroethylene (PTFE) is a per(halo)fluoromonomer having at least 98 mol% repeat units derived from tetrafluoroethylene, at least 98.5 mol%, at least 99 mol%, at least 99.5 mol%, or at least 99.9 mol% repeat units derived from tetrafluoroethylene, where mol% is based on the total number of moles of polymer (FP). Preferably, polymer (FP) contains 100 mol% repeat units derived from tetrafluoroethylene, based on the total number of moles in the polymer.

[0023] When all of the repeating units of PTFE are derived from tetrafluoroethylene, the PTFE is considered a "homopolymer."

[0024] According to another embodiment, the PTFE comprises up to 2 mol % of repeat units derived from ethylenically unsaturated fluorinated monomers other than tetrafluoroethylene, typically up to 1 mol %, up to 0.5 mol %, or up to 0.1 mol % of repeat units derived from ethylenically unsaturated monomers other than tetrafluoroethylene, based on the total number of moles of the polymer.

[0025] PTFE polymers well suited for the present invention are usually provided as fine powders, which can be obtained by irradiation of standard high molecular weight PTFE or modified PTFE, and are generally known to have molecular weights significantly lower than the typical molecular weights of standard high molecular weight / high melt viscosity PTFE / modified PTFE, and thus the fine powders of PTFE and / or modified PTFE can have melt flowability by themselves.

[0026] Preferably, the polymer (FP) is subjected to heat treatment at 372°C and 1000s using a 1 mm x 10 mm Hastelloy die according to ASTM D3835. -1 Up to 1.5 x 10 measured 3 The melt viscosity is selected from the group consisting of modified PTFE fine powders having a melt viscosity of up to 1.4×10 Pa.s. 3 Pa.s, max. 1.3×10 3 Pa.s, maximum 1.0×10 3 Pa.s, or up to 0.8 x 10 3 It may be Pa.s.

[0027] Fine powders of polymers (FP), such as PTFE or modified PTFE, which are well suited for the present invention, have their average particle size d determined by laser light diffraction according to ISO 13320. 50 According to one embodiment, the polymer (FP) fine powder can be characterized by d 50 is at most 25.0 μm, for example at most 22.0 μm, or at most 20.0 μm. 50 The lower limit of is not particularly limited. However, for convenience of handling, the d 50It is understood that is usually at least 0.5 μm, preferably at least 1.0 μm.

[0028] Average size d between 2.0 μm and 15.0 μm, preferably between 2.5 μm and 12.0 μm 50 Particularly good results have been obtained with fine powders of PTFE or modified PTFE having the formula:

[0029] Average size of PTFE or modified PTFE fine powder d 50 is determined according to ISO 13320 by laser light diffraction, for example using a laser diffraction particle sizer LS™ 13 320MW-Beckman Coulter instrument.

[0030] A PTFE fine powder that can be used in the films of the present invention is POLYMIST® micronized PTFE powder, available from Solvay Specialty Polymers USA, LLC.

[0031] In some further embodiments, the polymer (FP) used in the composite film of the present invention comprises, in addition to repeat units derived from tetrafluoroethylene, repeat units derived from at least one fluorinated monomer other than tetrafluoroethylene. This at least one additional monomer can be selected from the group consisting of: - Formula CF2=CFOR f (In the formula, R f is a C1 to C6 perfluoroalkyl group, preferably a C1 to C3 perfluoroalkyl group; - perfluoro-oxyalkyl vinyl ethers of the formula CF2=CFOX0, where X0 is a C1-C12 perfluorooxyalkyl group containing one or more ether groups, for example a perfluoro-2-propoxy-propyl group; - C3 to C8 perfluoroolefins such as hexafluoropropene (HFP); and - a perfluorodioxole of formula (I): [ka] (wherein R1, R2, R3, and R4 are the same or different and are independently selected from the group consisting of -F, a C1-C6 fluoroalkyl group optionally containing one or more oxygen atoms, and a C1-C6 fluoroalkoxy group optionally containing one or more oxygen atoms).

[0032] According to these embodiments, polymer (FP) preferably comprises repeat units derived from tetrafluoroethylene and at least 1.5 mol %, such as at least 5.0 mol %, or at least 7.0 mol %, of repeat units derived from at least one fluorinated monomer other than tetrafluoroethylene, based on the total number of moles in polymer (FP).

[0033] According to these embodiments, polymer (FP) preferably comprises up to 30.0 mol %, such as up to 25.0 mol %, or up to 20.0 mol %, of repeat units derived from tetrafluoroethylene and at least one fluorinated monomer other than tetrafluoroethylene, based on the total number of moles in polymer (FP).

[0034] In some advantageous embodiments, the polymer (FP) is a compound represented by the formula CF2=CFOR f perfluoroalkyl vinyl ether (wherein R f is a C1 to C6 perfluoroalkyl group, preferably a C1 to C3 perfluoroalkyl group.

[0035] The polymer (FP) advantageously comprises, based on the total number of moles in the polymer (FP), - 3.0 to 6.0 mol % of repeating units derived from perfluoroalkyl vinyl ethers selected from perfluoromethyl vinyl ether, prefluoroethyl vinyl ether, and perfluoropropyl vinyl ether; - 94.0 to 97.0 mol% of repeat units derived from tetrafluoroethylene; The copolymer may be selected from the group of tetrafluoroethylene / perfluoroalkyl vinyl ether copolymers including:

[0036] The polymer (FP) preferably has, based on the total number of moles in the polymer (FP), - 3.0 to 6.0 mol % of repeating units derived from perfluoromethyl vinyl ether or perfluoropropyl vinyl ether, - 94.0 to 97.0 mol % of repeating units derived from tetrafluoroethylene; The copolymer is selected from the copolymers comprising:

[0037] Preferably, the polymer (FP) is selected from the group consisting of tetrafluoroethylene / perfluoroalkyl vinyl ether copolymers, preferably tetrafluoroethylene / perfluoromethyl vinyl ether or tetrafluoroethylene / perfluoropropyl vinyl ether copolymers. More preferably, it is fused at 372° C. and 100 s using a 1 mm×10 mm Hastelloy die according to ASTM D3835. -1 Up to 1.8 x 10 measured 3 Pa.s, e.g. up to 1.7×10 3 Pa.s, max. 1.6×10 3 Pa.s, max. 1.5×10 3 Pa.s, or up to 1.4 x 10 3 The copolymer is selected from tetrafluoroethylene / perfluoroalkyl vinyl ether copolymers having a melt viscosity of 100 Pa.s, preferably tetrafluoroethylene / perfluoromethyl vinyl ether or tetrafluoroethylene / perfluoropropyl vinyl ether copolymers.

[0038] Non-limiting examples of suitable polymers (FP) include those commercially available under the trade names HYFLON® PFA P-series and M-series, and HYFLON® MFA, among others, from Solvay Specialty Polymers Italy SpA.

[0039] According to the invention, the fiber substrate (F) used in the composite film may be an aramid substrate, a glass fiber substrate or a quartz substrate.

[0040] Preferably, the fiber fabric (F) comprises glass fibers. More preferably, the glass fibers, and thus the glass fiber fabric, are characterized by a low dielectric constant and a low dielectric loss tangent.

[0041] In an advantageous embodiment, the fiberglass fabric is made from fibers comprising at least 33.0 parts by weight to 48.0 parts by weight of silicon oxide; 1.0 parts by weight to 5.0 parts by weight of alumina; 5.0 parts by weight to 10.0 parts by weight of titanium oxide; 0.5 parts by weight to 4.0 parts by weight of zirconium oxide; and at least one of the oxides holmium oxide, alkaline earth metal oxide, neodymium oxide, and iron oxide.

[0042] In a specific embodiment, the glass fiber fabric is made from fibers having the following composition: 35.0 to 48.0 parts by weight of silicon oxide, 1.0 to 5.0 parts by weight of alumina, 5.5 to 10.0 parts by weight of titanium oxide, 0.5 to 4.0 parts by weight of zirconium oxide, 3.0 parts by weight or less of holmium oxide, and 32.0 to 47.5 parts by weight of alkaline earth metal oxide, based on the total weight of the fiber. Alternatively, the glass fiber fabric is made from fibers having the following composition: 33.0 to 46.0 parts by weight of silicon oxide, 1.5 to 5.0 parts by weight of alumina, 5.0 to 10.0 parts by weight of titanium oxide, 0.5 to 4.0 parts by weight of zirconium oxide, 2.5 parts by weight or less of neodymium oxide, 1.2 parts by weight or less of iron oxide, and 31.0 to 53.0 parts by weight of alkaline earth metal oxide, based on the total weight of the fiber.

[0043] The glass fiber fabric may additionally or alternatively have a dielectric constant D at 1 GHz measured using the transmission line method and a vector network analyzer. k is less than 5.5, and the dielectric loss tangent D at 1 GHz measured using the transmission line method and a vector network analyzer f can be characterized by being less than 0.0030.

[0044] The fiberglass fabric preferably has a dielectric constant D at 1 GHz of less than 5.0, measured using the transmission line method and a vector network analyzer. k The dielectric constant at 1 GHz is D k The fiberglass fabric preferably has a dielectric loss tangent D at 1 GHz of less than 0.0025, or even less than 0.0020, measured using the transmission line method and a vector network analyzer. f The dielectric loss tangent D at 1GHz f is usually 0.0001 or more.

[0045] Fiberglass fabrics having the properties detailed above are available from Nittobo and CTG Taishan Fiberglass.

[0046] The fibrous fabric (F) may be woven or nonwoven. The fibrous fabric (F) may, for example, have an average thickness of about 200 μm or less, for example, 180 μm or less or 160 μm or less. The fibers in the fibrous fabric (F) may have an average diameter of about 25 μm or less, for example, 23 μm or less or 21 μm or less.

[0047] In some embodiments, the fiber fabric (F) has a fiber density of 10 g / m 2 ~100g / m 2 , e.g. 12g / m 2 ~90g / m 2 , or 15 g / m 2 ~80g / m 2 Average basis weight (grams / square meter or g / m 2 ) is a fabric having the following properties.

[0048] In some embodiments, the fiber fabric (F) is a fabric having a thickness of 0.01 mm to 0.09 mm, or even 0.02 mm to 0.07 mm.

[0049] The use of such fibrous fabrics in the films of the present invention is advantageous because they provide additional stiffness or dimensional stability as needed, and these characteristics can be advantageously optimized based on the selection of a particular fabric to meet the needs of a particular end use application.

[0050] A composite film exhibiting a thickness of less than 0.10 mm may be a multi-layer composite film, which may comprise several fiber fabrics (F), each of which may be the same or different. The fabrics may be of different thicknesses and / or of different composition. They may be oriented in different directions. For example, a composite film may consist of two, three, four, five and up to ten fiber fabrics superimposed on top of each other.

[0051] In the multilayer film of the present invention, the same polymer (FP) containing repeat units derived from tetrafluoroethylene as described herein may be present between each fiber texture, or a different polymer (FP) may be used between each fiber texture. Alternatively, chemically different polymers may be used to bond the layers together. Examples of such chemically different polymers include polyimides and liquid crystal polymers.

[0052] According to the present invention, the composite film preferably comprises less than about 75% by weight of the fiber fabric (F) per unit area of ​​the composite film, preferably 5-70% by weight or 10-60% by weight of the fiber fabric (F). At such weight percentages, the composite film easily follows the shrinkage of the fluoropolymer (e.g., PTFE, PFA film) when the composite film is cooled from high temperature.

[0053] According to the present invention, the composite film has a fiber volume (V f ) is preferably 20 to 60 volume %, for example 25 to 55 volume %, or 30 to 50 volume %, and Vf is calculated according to the following formula:

number

[0054] The composite films of the present invention exhibit several advantageous dielectric properties. In some embodiments, the composite films have the following dielectric properties: a dielectric constant Dk at 5 GHz, measured by split post dielectric resonator (SPDR), IEC 61189-2-721:2015, of less than or equal to 3.5, less than 3.0, or even less than 2.8, preferably less than 2.5, after drying at 100°C for 1 hour; and / or a dissipation factor Df at 5 GHz, measured by split post dielectric resonator (SPDR), IEC 61189-2-721:2015, of less than 0.0050, less than 0.0040, less than 0.0030 or even less than 0.0020 after drying at 100°C for 1 hour, and / or - a dielectric constant Dk at 20 GHz, measured according to a split cylinder resonator, IPC TM-650 2.5.5.13, of less than 3.0, or even less than 2.5, after drying at 100 °C for 1 hour; and / or - a dissipation factor Df at 20 GHz, measured according to a split cylinder resonator, IPC TM-650 2.5.5.13, of less than 0.0100, or even less than 0.0080, after drying at 100 °C for 1 hour; and / or - a dielectric constant Dk at 5 GHz, measured by split post dielectric resonator (SPDR), IEC 61189-2-721:2015, of less than 3.5, or even less than 3.0, after immersion in water for 24 hours; and / or - a dissipation factor Df at 5 GHz, measured by a split post dielectric resonator (SPDR), IEC 61189-2-721:2015, of less than 0.005, or even less than 0.004, after immersion in water for 24 hours; and / or - a dielectric constant Dk at 20 GHz, measured by split cylinder resonator, IPC TM-650 2.5.5.13, of less than 3.0, or even less than 2.9, after immersion in water for 24 hours; and / or – Dissipation factor Df at 20 GHz less than 0.0300, or even less than 0.0100, measured by split cylinder resonator, IPC TM-650 2.5.5.13, after immersion in water for 24 hours.

[0055] In some embodiments, the composite film may have the following combination of dielectric properties: - a dielectric constant Dk at 5 GHz, measured by split post dielectric resonator (SPDR), IEC 61189-2-721:2015, of less than 3.0, or even less than 2.8, after drying at 100°C for 1 hour; and - a dissipation factor Df at 5 GHz, measured by split post dielectric resonator (SPDR), IEC 61189-2-721:2015, of less than 0.0030, or even less than 0.0020, after drying at 100°C for 1 hour; and - a dielectric constant Dk at 20 GHz, measured according to a split cylinder resonator, IPC TM-650 2.5.5.13, of less than 2.8 after drying at 100 °C for 1 hour, and / or - a dissipation factor Df at 20 GHz, measured by a split cylinder resonator, IPC TM-650 2.5.5.13, of less than 0.0080 after drying at 100 °C for 1 hour, and / or - a dielectric constant Dk at 5 GHz, measured by split post dielectric resonator (SPDR), IEC 61189-2-721:2015, of less than 3.5, or even less than 3.0, after immersion in water for 24 hours; and / or - a dissipation factor Df at 5 GHz, measured by split post dielectric resonator (SPDR), IEC 61189-2-721:2015, of less than 0.0050, or even less than 0.0040, after immersion in water for 24 hours; and / or - a dielectric constant Dk at 20 GHz, measured by split cylinder resonator, IPC TM-650 2.5.5.13, of less than 3.0, or even less than 2.9, after immersion in water for 24 hours; and / or – Dissipation factor Df at 20 GHz less than 0.0300, or even less than 0.0100, measured by split cylinder resonator, IPC TM-650 2.5.5.13, after immersion in water for 24 hours.

[0056] In some embodiments, the composite film exhibits the following combination of dielectric properties: - Dk at 5 GHz less than 2.5, and / or - Df at 5 GHz less than 0.0015; and / or - Dk at 20 GHz less than 2.5; and / or - Df at 20 GHz less than 0.0050; and / or - Dk at 50 GHz less than 3.0, or even less than 2.8; and / or - Df at 50 GHz less than 0.0030, or even less than 0.0025; and / or - Dk at 75 GHz less than 3.0, or even less than 2.8; and / or - Df at 75 GHz less than 0.0030, or even less than 0.0025; and / or - Dk at 100 GHz less than 3.0, or even less than 2.8; and / or - Df at 100 GHz less than 0.0030, or even less than 0.0025; where Dk is measured by split cylinder resonator, IPC TM-650 2.5.5.13 after drying at 100°C for 1 hour, and Df is measured by split post dielectric resonator (SPDR), IEC 61189-2-721:2015 after drying at 100°C for 1 hour.

[0057] In some embodiments, the film has a melting point of about 50×10 at a temperature range of 0° C. to 300° C. -6 / ℃, e.g. 40×10 -6 / ℃ or less than 30×10 -6 According to this embodiment, the film has a coefficient of thermal expansion (CTE) of at least 1×10 -6 / °C or at least 4 x 10 -6 / °C.

[0058] Manufacturing method of composite film The composite films of the present invention can be made in several different embodiments.

[0059] Some of these methods can start from a polymer powder comprising at least one polymer (FP) applied to at least one surface of a fiber substrate (F). According to these methods, the powder of at least one polymer (FP) applied to at least one surface of the fiber substrate is 50 is in the range of 0.1 to 100 μm, preferably 1 to 90 μm, or 5 to 80 μm. 50 can be measured by laser scattering in isopropanol. The polymer powder contains fillers and other additives well known in the art. Such fillers and additives can include, for example, organic or inorganic particles, plasticizers, light and weather stabilizers, antistatic agents, UV absorbers, dyes, pigments, viscosity agents, and lubricants.

[0060] One method of the invention for producing a composite film exhibiting a thickness of less than 0.1 mm comprises the following steps: a) applying a powder containing at least one polymer (FP) to at least one surface of a fiber fabric, the powder containing at least one polymer (FP) having a particle size of 0.1 to 100 μm; 50 A process comprising the steps of: b) bonding a powder of at least one polymer (FP) to the textile fabric at a pressure P of at least 0.3 MPa and / or at a temperature T such that T≧Tm, Tm being the melting temperature (° C.) of the polymer powder;

[0061] At the temperatures and pressures mentioned above, the polymer powder undergoes a phase change (typically melts) and can become firmly bonded to the fiber substrate.

[0062] In some preferred embodiments, the polymer (FP) powder is applied to both sides of the textile substrate. A protective film may be used to apply the polymer (FP) powder to both sides of the textile substrate.

[0063] Preferably, step b) is carried out at a pressure P of at least 0.4 MPa, at least 0.5 MPa, or at least 0.5 MPa, and / or at a temperature T such that T≧Tm, where Tm is the melting temperature of the polymer powder (° C.). In some embodiments, T is a temperature such that T≧Tm+5° C. In some embodiments, T is a temperature such that 310° C.≦T≦T400° C., such as 320° C.≦T≦T390° C., or 325° C.≦T≦T380° C., or 330° C.≦T≦T360° C.

[0064] Step b) consists, for example, in compression moulding the fibre fabric to which the polymer powder has been applied, using a hot press.

[0065] When a molding press is used in the method of the present invention, a release film can be used between the film and the platens of the press to prevent sticking of the film to the platens. Any release film that does not interfere with or change the properties of the composite film is suitable. The release film can be, for example, polyimide or a metal foil such as aluminum with a release coating.

[0066] The process may be a batch process, meaning that individual films may be formed one at a time using a stack press, for example in an autoclave or vacuum / oven, or it may be a continuous process, for example where the polymer powder is continuously spread over at least one fiber fabric, with or without one or more rolls of fiber fabric, and bonded to it by high pressure and high temperature using a double belt press. The residence time in the press when the polymer powder exceeds its melting point is 0.5 to 1,000 seconds. A typical double belt press may have a heating zone and a cooling zone.

[0067] The amount of pressure and temperature applied to the film depends on the type of polymer used, the fiber fabric used, and their respective physical and dimensional properties, as well as the operating, physical, and dimensional properties of the press. The melting point of the polymer powder is an important feature, along with the size of the polymer powder, the thickness of the fiber fabric, the heat transfer capacity, and of course the thickness of the composite film (including multi-layer structures). Also, the heat transfer properties of the (press) platens, their size and thickness, the residence time of the film in the press, etc. are very important. For example, for polymer powders containing the tetrafluoroethylene / perfluoroalkylvinylether copolymer mentioned above, the temperature should be above about 305°C. A particularly preferred temperature range is about 330°C to 360°C. When this particular polymer is used with a fiber fabric having an average thickness of about 0.06 mm, the pressure applied to such a composite film should be in the range of 0.3 MPa to 1.0 MPa.

[0068] One method of the invention for producing a composite film exhibiting a thickness of less than 0.1 mm comprises the following steps: a) applying a polymer powder containing at least one polymer (FP) to at least one surface of a fiber fabric, the polymer powder containing at least one polymer (FP) being 0.1 to 100 μm in diameter; 50 A process showing b) Sintering the polymer powder onto the textile substrate by electromagnetic, infrared or near infrared radiation.

[0069] The polymer powder may be applied by electrostatic spraying.

[0070] According to this method, polymer powder is sintered onto the surface of a textile fabric using electromagnetic, infrared, or near infrared radiation, e.g. a high power laser source, such as an electromagnetic beam source.

[0071] Another method of the present invention for producing a composite film exhibiting a thickness of less than 0.1 mm can start with a polymeric material in the form of a slurry or dispersion.

[0072] Another method of the invention for producing a composite film exhibiting a thickness of less than 0.1 mm starts from a polymer in the form of a thin film, which may consist of the polymer (FP) described herein or may contain additional components or additives.

[0073] One of these methods for producing a composite film exhibiting a thickness of less than 0.1 mm comprises the following steps: a) applying a polymeric film comprising at least one polymer (FP) to at least one surface of a textile fabric, the polymeric film exhibiting a thickness of less than 0.09 mm; b) bonding the polymer film to the textile substrate at a pressure P of at least 0.3 MPa and / or at a temperature T such that T≧Tm, Tm being the melting temperature (° C.) of the polymer (FP).

[0074] Another method for producing a composite film exhibiting a thickness of less than 0.1 mm comprises the following steps: a) applying a polymeric film comprising at least one polymer (FP) to at least one surface of a textile fabric, the polymeric film exhibiting a thickness of less than 0.09 mm; b) Sintering the polymer film to the textile substrate, for example by electromagnetic, infrared or near infrared radiation.

[0075] Method for producing multi-layer composite film According to the invention, multiple separate composite films can be laminated together to produce a multi-layer composite film. The composite films can be, for example, oriented in the same direction and / or they can be oriented in different directions. If necessary, a new cycle (or multiple cycles) of compression molding can be performed on the stacked multi-layer structure using a hot press.

[0076] Alternatively, the multilayer composite film may include: a) applying a polymer powder comprising at least one polymer (FP) to at least one surface of at least two fiber substrates; b) stacking at least two fiber fabrics on top of each other; and c) bonding the polymer powder to the textile fabric at a pressure P of at least 0.3 MPa and / or a temperature T >= Tm, where Tm is the melting temperature (°C) of the polymer powder; It can be produced by

[0077] Alternatively, step c) may consist of sintering the polymer powder, as described above.

[0078] In some embodiments, the polymer powder is in the form of a slurry, for example a wet slurry.

[0079] In some alternative embodiments, the polymer may be in the form of a thin film (preferably less than 0.09 mm) that is melted to bond with the fiber fabric.

[0080] Several of these options can be used to produce one multi-layer composite film according to the present invention.

[0081] End use Although the composite films of the invention are characterized by a thickness of less than 0.10 mm, the invention also relates to assemblies of composite films according to the invention, which can result in a final assembly having a thickness of more than 0.10 mm.

[0082] The present invention also relates to an article or construction comprising at least one composite film as described above and an optional metal layer, preferably a copper layer, which is adhered to at least one of the surfaces of the composite layer.

[0083] The present invention also relates to the use of at least one composite film for manufacturing articles or components of portable electronic devices, such as flexible printed circuit boards (FPCs).

[0084] The composite films of the present invention can be used, inter alia, to manufacture flexible printed circuit boards (FPCs), carrier tapes for tape automated bonding (TAB), and tapes for lead-on-chip (LOC) structures.

[0085] The invention also relates to the use of a powder of polymer (FP) for producing a composite film having a thickness of less than 0.10 mm, said composite film further comprising at least one fibrous substrate (F). EXAMPLES

[0086] The present disclosure will now be described in more detail with reference to the following examples, the purpose of which is merely illustrative and is not intended to limit the scope of the present disclosure.

[0087] Starting materials Glass Fabric GF-1: Fiberglass® Fabric 108, commercially available from BGF Industries, 48 ​​gsm, 0.06 mm / 2.4 mil thickness, 5 μm fiber diameter

[0088] Glass blank GF-2: Blank LD1035-127, commercially available from CTG Taishan Fiberglass; dielectric constant Dk@1GHz of 4.3~4.5, dissipation factor Df@1GHz of 0.0016, both Dk and Df measured using the transmission line method and a vector network analyzer.

[0089] PFA-1: Hyflon® PFA P7010, a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer commercially available from Solvay Specialty Polymers, Tm=305° C., d of 30 μm 50

[0090] PFA-2: Hyflon® PFA P7010, commercially available from Solvay Specialty Polymers, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, Tm=305° C., d of 150 μm 50 .

[0091] Film Manufacturing Method The PFA polymer powder was dispersed on glass fabric (GF-1 or GF-2) in a polymer / fabric / polymer configuration. The resulting combination of ingredients was then compression molded into a thin composite film using a hot press set at a temperature of 330° C. and a pressure of 1 MPa. The film was heated for approximately 10 minutes. The polymer powder melted and soaked into the fabric fibers. The film was immediately removed from the press and placed on a cold bench top to return to ambient temperature. The composition and properties of the composite films are reported in the Results section below.

[0092] Test Method Dielectric performance (Dk, Df) The dielectric constant Dk and dissipation factor Df were measured at 5 GHz by a split post dielectric resonator (SPDR), IEC 61189-2-721:2015, after drying at 100 °C for 1 h and after immersion in water for 24 h. The dielectric constant Dk and dissipation factor Df were measured at 20 GHz by a split cylinder resonator, IPC TM-650 2.5.5.13, after drying at 100°C for 1 hour and after immersion in water for 24 hours.

[0093] Coefficient of Thermal Expansion (CTE) CTE was measured using a TMA instrument in tensile mode according to ASTM D696.

[0094] Tensile strength Tensile tests were performed using an Instron® mechanical testing machine according to ASTM D882.

[0095] Fiber volume The volume of the fibre (Vf) is calculated according to the following formula:

number

[0096] result

[0097] [Table 1]

[0098] [Table 2]

[0099] The data in Table 2 show the excellent dielectric properties of the composite films of the present invention at frequencies above 10 GHz. The dielectric properties remain consistently good up to 100 GHz.

[0100] [Table 3]

[0101] Comparing the Dk and Df values ​​of Film #2 reported in Table 2 with those of Film #3 in Table 3, it is clear that the composite film manufacturing process has a d 50 It is shown that the excellent dielectric properties of the composite film can be further improved when fluoropolymer particles having

[0102] Better dielectric properties can also be obtained when using fiberglass fabrics with lower Dk and Df values, such as GF-2.

Claims

1. A composite film having a thickness of less than 0.10 mm, at least one fluoropolymer [polymer (FP)] comprising repeat units derived from tetrafluoroethylene, and - at least one textile fabric [textile fabric (F)] A composite film comprising:

2. The polymer (FP) - Formula CF ２ =CFOR ｆ (In the formula, R ｆ is a C1-C6 perfluoroalkyl group; - Formula CF2=CFOX ０ (In the formula, X ０ is a C1-C12 perfluorooxyalkyl group containing one or more ether groups, for example a perfluoro-2-propoxy-propyl group; - C3 to C8 perfluoroolefins such as hexafluoropropene (HFP); and perfluorodioxoles of formula (I): 【Chemistry 1】 (In the formula, R １ , R ２ , R ３ , and R ４ are the same or different and are independently selected from the group consisting of -F, a C1-C6 fluoroalkyl group optionally containing one or more oxygen atoms, and a C1-C6 fluoroalkoxy group optionally containing one or more oxygen atoms; 2. The composite film according to claim 1, further comprising repeat units derived from at least one fluorinated monomer other than tetrafluoroethylene selected from the group consisting of: repeat units derived from tetrafluoroethylene; and less than 10 mol % of repeat units derived from at least one fluorinated monomer other than tetrafluoroethylene, based on the total number of moles in the polymer (FP).

3. The polymer (FP) has a molecular weight of 1:1 or more based on the total number of moles in the polymer (FP). - 3.0 to 6.0 mole % of repeat units derived from perfluoroalkyl vinyl ethers selected from the group consisting of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, and perfluoroproyl vinyl ether; - 94.0 to 97.0 mol % of repeat units derived from tetrafluoroethylene, 2. The composite film of claim 1 which is a tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer comprising:

4. 2. The composite film of claim 1, wherein the polymer (FP) is a per(halo)fluoropolymer having at least 98 mol % of repeat units derived from tetrafluoroethylene, based on the total number of moles in the polymer (FP).

5. 2. The composite film of claim 1, wherein the fibrous substrate (F) comprises glass fibers.

6. The glass fiber is i) based on the total mass of the fibers, 35.0 to 48.0 parts by mass of silicon oxide; 1.0 to 5.0 parts by mass of alumina; 5.5 to 10.0 parts by mass of titanium oxide; 0.5 to 4.0 parts by mass of zirconium oxide; 3.0 parts by mass or less of holmium oxide; 32.0 to 47.5 parts by mass of alkaline earth metal oxide; or ii) based on the total mass of the fibers, 33.0 to 46.0 parts by mass of silicon oxide; 1.5 to 5.0 parts by mass of alumina; 5.0 to 10.0 parts by mass of titanium oxide; 0.5 to 4.0 parts by mass of zirconium oxide; 2.5 parts by mass or less of neodymium oxide; 1.2 parts by mass or less of iron oxide; 31.0 to 53.0 parts by mass of alkaline earth metal oxide; 6. The composite film of claim 5, wherein the fibers are selected from fibers comprising

7. The glass fiber has a dielectric constant D at 1 GHz measured using a transmission line method and a vector network analyzer. ｋ is less than 5.5, and the dielectric loss tangent D at 1 GHz measured using the transmission line method and a vector network analyzer ｆ The composite film of claim 5, wherein:

8. The composite film of claim 1 , wherein the fibrous fabric (F) comprises a woven fabric.

9. The fiber fabric (F) has a thickness of 10 to 100 g / m ２ The composite film of claim 1 having an average basis weight comprised within the range of

10. a dielectric constant Dk at 5 GHz, measured by split post dielectric resonator (SPDR), IEC 61189-2-721:2015, of less than or equal to 3.5, less than 3.0, or even less than 2.8, preferably less than 2.5, after drying at 100°C for 1 hour; and / or - a dissipation factor Df at 5 GHz, measured by split post dielectric resonator (SPDR), IEC 61189-2-721:2015, of less than 0.0050, less than 0.0040, less than 0.0030 or even less than 0.0020, after drying at 100 °C for 1 hour; 2. The composite film of claim 1 having the formula:

11. a dielectric constant Dk at 20 GHz, measured by split cylinder resonator, IPC TM-650 2.5.5.13, of less than 3.0, or even less than 2.5, after drying at 100°C for 1 hour; and / or - a dissipation factor Df at 20 GHz, measured by split cylinder resonator, IPC TM-650 2.5.5.13, of less than 0.0100, or even less than 0.0080, after drying at 100 ° C for 1 hour; 2. The composite film of claim 1 having the formula:

12. a dielectric constant Dk at 20 GHz, measured by split cylinder resonator, IPC TM-650 2.5.5.13, of less than 3.0, or even less than 2.9, after immersion in water for 24 hours; and / or a dissipation factor Df at 20 GHz, measured by a split cylinder resonator, IPC TM-650 2.5.5.13, after immersion in water for 24 hours, of less than 0.0300, or even less than 0.0100; 2. The composite film of claim 1 having the formula:

13. - Dk at 50 GHz less than 3.0, even less than 2.8; and / or - Df at 50 GHz less than 0.0030, or even less than 0.0025; 10. The composite film of claim 1 having A composite film, wherein the Dk is measured by a split cylinder resonator, IPC TM-650 2.5.5.13 after drying at 100°C for 1 hour, and the Df is measured by a split post dielectric resonator (SPDR), IEC 61189-2-721:2015 after drying at 100°C for 1 hour.

14. - Dk at 75 GHz less than 3.0, even less than 2.8; and / or - Df at 75 GHz less than 0.0030, or even less than 0.0025; 10. The composite film of claim 1 having A composite film, wherein the Dk is measured by a split cylinder resonator, IPC TM-650 2.5.5.13 after drying at 100°C for 1 hour, and the Df is measured by a split post dielectric resonator (SPDR), IEC 61189-2-721:2015 after drying at 100°C for 1 hour.

15. - Dk at 100 GHz less than 3.0, even less than 2.8; and / or - Df at 100 GHz less than 0.0030, or even less than 0.0025; 10. The composite film of claim 1 having A composite film, wherein the Dk is measured by a split cylinder resonator, IPC TM-650 2.5.5.13 after drying at 100°C for 1 hour, and the Df is measured by a split post dielectric resonator (SPDR), IEC 61189-2-721:2015 after drying at 100°C for 1 hour.

16. A method for producing a composite film according to any one of claims 1 to 15, comprising the step of applying a polymer powder comprising at least one polymer (FP) to at least one surface of a fibrous substrate (F).

17. a) applying a polymer powder comprising at least one polymer (FP) to at least one surface of a textile fabric, said powder comprising at least one polymer (FP) being comprised between 0.1 and 100 μm; ５０ A process comprising the steps of: b) bonding a powder of at least one polymer (FP) to the textile fabric by applying a pressure P of at least 0.3 MPa and / or a temperature T such that T≧Tm, Tm being the melting temperature (° C.) of the polymer powder; 17. The method of claim 16, comprising:

18. 18. The method according to claim 17, wherein step b) is carried out at a pressure P of at least 0.5 MPa and / or at a temperature T such that T > Tm + 5°C.

19. The fiber fabric (F) i) based on the total mass of the fibers, 35.0 to 48.0 parts by mass of silicon oxide; 1.0 to 5.0 parts by mass of alumina; 5.5 to 10.0 parts by mass of titanium oxide; 0.5 to 4.0 parts by mass of zirconium oxide; 3.0 parts by mass or less of holmium oxide; 32.0 to 47.5 parts by mass of alkaline earth metal oxide; or ii) based on the total mass of the fibers, 33.0 to 46.0 parts by mass of silicon oxide; 1.5 to 5.0 parts by mass of alumina; 5.0 to 10.0 parts by mass of titanium oxide; 0.5 to 4.0 parts by mass of zirconium oxide; 2.5 parts by mass or less of neodymium oxide; 1.2 parts by mass or less of iron oxide; 31.0 to 53.0 parts by mass of alkaline earth metal oxide; The method of claim 16, wherein the fiberglass fabric comprises fibers comprising

20. The fiber fabric (F) has a dielectric constant D at 1 GHz measured using a transmission line method and a vector network analyzer. ｋ is less than 5.5, and the dielectric loss tangent D at 1 GHz measured using the transmission line method and a vector network analyzer ｆ The method of claim 16, wherein is less than 0.0030.

21. 16. An article or component of an article comprising at least one composite film according to any one of the preceding claims and optionally a metal layer, preferably a copper layer, adhered onto at least one surface of said composite film.

22. Use of at least one composite film according to any one of claims 1 to 15 for producing a portable electronic device article or a component thereof, preferably a flexible printed circuit board (FPC).

23. Powders comprising at least one polymer (FP) for producing composite films having a thickness of less than 0.10 mm, preferably d comprised between 0.1 and 100 μm ５０ The use of a powder having the formula: wherein the polymer (FP) comprises repeating units derived from tetrafluoroethylene (TFE), and the composite film further comprises at least one fiber fabric (F).

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