CN119212860A

CN119212860A - Flexible Laminates

Info

Publication number: CN119212860A
Application number: CN202380039902.3A
Authority: CN
Inventors: B·阿莫斯; J·C·弗兰科斯基; F·C·J·许尔泽博施; S·肯尼迪; 刘晓琳; 王瑛; R·T·扬
Original assignee: Chemours Co FC LLC
Current assignee: Chemours Co FC LLC
Priority date: 2022-07-06
Filing date: 2023-07-05
Publication date: 2024-12-27
Also published as: TW202402540A; KR20250036831A; WO2024010787A1

Abstract

A laminate comprising a dielectric substrate comprising a perfluorocopolymer matrix comprising a fluorinated perfluorocopolymer and a non-fluorinated perfluorocopolymer, an L-glass fabric embedded in the perfluorocopolymer matrix, and an additive material dispersed in the perfluorocopolymer matrix, wherein the additive material is capable of absorbing ultraviolet light, and a conductive coating disposed on a surface of the dielectric substrate.

Description

Flexible laminate

Background

Metal clad laminates are used as printed wiring board substrates in a variety of electronic device applications.

Disclosure of Invention

In one aspect, a laminate includes a dielectric substrate comprising a perfluorocopolymer matrix comprising a fluorinated perfluorocopolymer and a non-fluorinated perfluorocopolymer, an L-glass fabric embedded in the perfluorocopolymer matrix, and an additive material dispersed in the perfluorocopolymer matrix, wherein the additive material is capable of absorbing ultraviolet light, and a conductive coating disposed on a surface of the dielectric substrate.

Implementations may include any combination of one or two or more of the following features.

The L-glass fabric comprises yarns of L-glass, NL-glass or L2-glass.

The laminate has a thickness of 20 μm to 200 μm, for example 30 μm to 90 μm or 30 μm to 60 μm.

The dielectric substrate has a dielectric constant of 2.10 to 2.70, for example 2.10 to 2.40, at 10 GHz.

The dielectric substrate has a thermal coefficient of permittivity having a value of-250 ppm/°c to +50ppm/°c over a temperature range of 0 ℃ to 100 ℃.

The dielectric substrate has a dissipation factor at 10GHz of less than 0.0015, e.g., 0.0006 to 0.001 or 0.0006 to 0.0008.

The laminate has a planar shape defining an X-Y plane, and wherein the thermal expansion coefficient of the laminate in the X-Y plane is from 5ppm/°c to 25ppm/°c, such as from 14ppm/°c to 20ppm/°c or from 16ppm/°c to 22ppm/°c.

Fluorinated perfluoro copolymers include fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymers, and wherein non-fluorinated perfluoro copolymers include non-fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymers.

The perfluorocopolymer matrix comprises 50 to 90 weight percent fluorinated perfluorocopolymer, for example 10 to 50 weight percent non-fluorinated perfluorocopolymer.

The number of carboxyl end groups per million carbon atoms in the perfluorocopolymer matrix is sufficient to render the laminate non-Conductive Anode Filament (CAF).

The number of carboxyl end groups per million carbon atoms in the perfluorocopolymer matrix provides the laminate with a peel strength of greater than 2 lbs/inch between the dielectric substrate and the conductive coating.

The number of carboxyl end groups per million carbon atoms in the perfluorocopolymer matrix is from 30 to 70.

The fluorinated perfluorocopolymer has 5 or fewer carboxyl end groups per million carbon atoms.

The non-fluorinated perfluorinated copolymers have 100 to 300 carboxyl end groups per million carbon atoms.

The perfluorocopolymer matrix has a Melt Flow Rate (MFR) of 10 g/10 min to 30 g/10 min.

The perfluorocopolymer matrix has a float weld resistance (solder float resistance) of at least 10 seconds at 288 ℃.

The L-glass has a basis weight of less than 100g/m2, for example less than 50g/m 2.

The L-glass fabric has a thickness of 10 μm to 100 μm, for example, 10 μm to 30 μm.

The L-glass fabric includes an aminosilane or methacrylate silane surface chemical treatment.

The L-glass fabric includes a plasma-treated or corona-treated L-glass fabric.

The L-glass fabric is impregnated with a fluoropolymer.

The L-glass fabric includes a fluoropolymer coating.

The L-glass fabric is pre-treated with a fluoropolymer treatment prior to incorporation into the laminate.

The dielectric substrate comprises 5 to 20 volume percent of the L-glass fabric and 80 to 95 volume percent of the perfluorocopolymer matrix.

The water contact angle of the L-glass fabric is 0 DEG to 60 deg.

The additive material comprises inorganic particles such as particles of cerium oxide, titanium dioxide, silicon dioxide, barium titanate, calcium titanate or zinc oxide.

The additive material comprises a thermosetting polymer.

The additive material is present in the perfluorocopolymer matrix in a volume percentage of less than 2%.

The additive material is uniformly dispersed throughout the perfluorocopolymer matrix.

Conductive plating is disposed on two opposing surfaces of the dielectric substrate.

The conductive plating layer includes copper foil. In some cases, the copper foil is disposed on the surface of the dielectric substrate by a lamination process.

The conductive coating has a thickness of less than 72 μm, for example 5 μm to 18 μm.

The conductive coating has a Root Mean Square (RMS) roughness of less than 1 μm, for example less than 0.5 μm.

In one aspect, a printed wiring board includes a laminate having any of the foregoing features, wherein a conductor pattern is formed in the conductive plating.

Defining a through hole through the thickness of the laminate, and including a copper film plating the through hole.

In one aspect, a multilayer printed wiring board comprises a multilayer laminate structure comprising a plurality of printed wiring boards according to the previous aspect.

The multilayer printed wiring board includes a thermoplastic adhesive disposed between adjacent printed wiring boards in a laminate structure. In some cases, the thermoplastic adhesive bonds at a temperature from 0 ℃ to 200 ℃ below the melting point of the perfluorocopolymer matrix. In some cases, the thermoplastic adhesive bonds at a temperature from 0 ℃ to 50 ℃ below the melting point of the perfluorocopolymer matrix.

The multilayer printed wiring board includes a thermosetting adhesive disposed between adjacent printed wiring boards in a laminate structure. In some cases, the thermoset adhesive cures at a temperature of 150 ℃ to 250 ℃.

Defining a via through at least a portion of the thickness of the multilayer printed wiring board, and including a copper film plating the via.

An antenna capable of use with a 5G communication network may comprise a printed wiring board according to the preceding aspects.

In one aspect, a method of manufacturing a multilayer printed wiring board includes forming a conductor pattern in a conductive plating of each of a plurality of laminates having any of the foregoing features to form a corresponding printed wiring board, and laminating the plurality of printed wiring boards to form a multilayer laminate structure.

Laminating a plurality of printed wiring boards includes using a thermoplastic adhesive to adhere adjacent printed wiring boards. In some cases, the method includes bonding the thermoplastic adhesive at a temperature from 0 ℃ to 200 ℃ below the melting point of the perfluorocopolymer matrix. In some cases, the method includes bonding the thermoplastic adhesive at a temperature from 0 ℃ to 50 ℃ below the melting point of the perfluorocopolymer matrix.

Laminating a plurality of printed wiring boards includes using a thermosetting adhesive to adhere adjacent printed wiring boards. In some cases, the method includes curing the thermosetting adhesive at a temperature of 150 ℃ to 250 ℃.

The method includes defining a through hole through at least a portion of a thickness of the multi-layer laminate structure. In some cases, the method includes defining the via during ultraviolet laser drilling.

In one aspect, a method of making a laminate includes forming a laminate including a first polymer film and a second polymer film, each film including a perfluorocopolymer matrix including a fluorinated perfluorocopolymer and a non-fluorinated perfluorocopolymer, and an additive material capable of absorbing ultraviolet light, an L-glass fabric disposed between the first polymer film and the second polymer film, and a conductive coating disposed in contact with the first film, and applying heat and pressure to the laminate to form the laminate.

Fluorinated perfluorinated copolymers include fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymers, and non-fluorinated perfluorinated copolymers include non-fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymers.

Applying heat and pressure to the layered article includes compressing the layered article in a heated platen.

Applying heat and pressure to the laminate includes treating the laminate in a roll-to-roll lamination process.

Applying heat and pressure to the layered article includes applying a temperature to the layered article that is between 10 ℃ and 30 ℃ above the melting point of the perfluorocopolymer matrix.

Applying heat and pressure to the layered article includes applying a temperature of 300 ℃ to 400 ℃ to the layered article.

Applying heat and pressure to the laminate includes applying a pressure of 200psi to 1000psi to the laminate.

The method includes forming a first film and a second film in a melt processing and extrusion process. In some cases, forming the first film and the second film includes mixing a fluorinated perfluorinated copolymer and a non-fluorinated perfluorinated copolymer. In some cases, the method includes dispersing the additive material in the fluorinated perfluorocopolymer prior to mixing the fluorinated perfluorocopolymer and the non-fluorinated perfluorocopolymer.

The method includes treating the L-glass fabric with a fluoropolymer treatment. In some cases, treating the L-glass fabric with the fluoropolymer treatment includes coating the L-glass fabric with a fluoropolymer coating. In some cases, coating the L-glass fabric with the fluoropolymer coating includes coating the L-glass fabric in a solution coating process. In some cases, coating the L-glass fabric with the fluoropolymer coating includes depositing fluoropolymer particles on a surface of the L-glass fabric.

Each polymer film comprises a first layer comprising a fluorinated perfluorinated copolymer and a non-fluorinated perfluorinated copolymer and a second layer comprising a non-fluorinated perfluorinated copolymer, and wherein each second layer is disposed in contact with the quartz fabric and each second layer is disposed in contact with the conductive plating. The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.

Drawings

Fig. 1 is an illustration of a flexible metal clad laminate.

Fig. 2 is an illustration of a layered structure of a flexible metal clad laminate.

Fig. 3A and 3B are illustrations of laminates having conductive anode wires.

Fig. 4 and 5 are illustrations of printed wiring boards.

Fig. 6 is an illustration of a communication network.

Fig. 7 is an illustration of a roll-to-roll lamination process.

Fig. 8 is a flow chart of a method of manufacturing a flexible metal clad laminate.

Fig. 9 is a photograph of a flexible copper clad laminate.

Fig. 10 is a graph of the thickness of various flexible copper clad laminates.

Fig. 11 is a graph of the resin content of various flexible copper clad laminates.

Fig. 12A and 12B are graphs of dimensional stability measurements of various flexible copper clad laminates.

Fig. 13 is a graph of the planarity of various flexible copper clad laminates.

Fig. 14 is a graph of the thickness of various flexible copper clad laminates.

Fig. 15 is a graph of the resin content of various flexible copper clad laminates.

Fig. 16 is a graph of dielectric constants of various flexible copper clad laminates.

Figure 17 is a graph of dissipation factors for various flexible copper clad laminates.

Fig. 18A and 18B are graphs of dimensional stability measurements of various flexible copper clad laminates.

Figure 19 is a graph of dissipation factor of blended PFA films as a function of the number of carboxyl end groups per 106 carbon atoms in the film.

Figure 20 is a graph of the dissipation factor of the laminate as a function of the number of carboxyl end groups per 106 carbon atoms in the blended PFA film.

Fig. 21 is a graph of copper peel strength of the laminate as a function of the number of carboxyl end groups per 106 carbon atoms in the blended PFA film.

Detailed Description

We describe herein a metal clad flexible laminate having a low dielectric constant and low dissipation at high frequencies (e.g., 10 GHz). The flexible laminates described herein may be used in substrates for printed wiring boards in high frequency applications, such as antennas for use in 5G cellular communication networks or with automotive radar, among other applications. The flexible laminates described herein include a dielectric substrate formed from a perfluorocopolymer matrix having an L-glass fabric, such as a woven L-glass fabric, embedded therein. The perfluorocopolymer matrix comprises fully fluorinated perfluorocopolymers (referred to herein as "fluorinated perfluorocopolymers") and fully fluorinated perfluorocopolymers (referred to herein as "non-fluorinated perfluorocopolymers"), such as fully fluorinated and fully fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymers. The additive material in the dielectric substrate is capable of absorbing ultraviolet light so that the laminate can be drilled with an ultraviolet laser, for example, for forming vias through the thickness of the laminate. The flexible laminate is coated on one or both sides with a conductive coating, such as copper foil.

The presence of the L-glass fabric results in a laminate having a high degree of flatness, e.g., sufficient to enable alignment between the layers of the laminate during the drilling process. For example, in a multilayer laminate structure, the high planarity enables alignment during drilling of vias through the thickness of the multilayer structure. Without being bound by theory, it is believed that the difference between the Coefficient of Thermal Expansion (CTE) of the L-glass fabric and the CTE of the perfluorocopolymer matrix, and the relatively low modulus of the L-glass fabric (e.g., as compared to quartz fabric) results in the L-glass fabric shrinking sufficiently little during cooling of the laminate to avoid waviness in the laminate.

Referring to fig. 1, a metal-clad flexible laminate 100 includes a dielectric substrate 102 and conductive plating, such as metal (e.g., copper) foils 104a, 104b (collectively conductive plating 104) disposed on top and bottom surfaces 106a, 106b, respectively, of the dielectric substrate 102. Although in fig. 1 the conductive plating 104 is present on both surfaces 106a, 106b of the dielectric substrate 102, in some examples the conductive plating is provided on only a single surface (e.g., only the top surface 106 a) of the dielectric substrate 102.

The dielectric substrate 102 of the flexible laminate 100 includes an L-glass fabric 108, such as a woven L-glass fabric (e.g., L-glass, NL-glass, or L2-glass yarns woven into the fabric), embedded in a perfluorocopolymer matrix 110 that comprises fluorinated and non-fluorinated perfluorocopolymers, such as fluorinated and non-fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymers. As discussed further below, the perfluorocopolymer matrix 110 provides a low dielectric constant and low dissipation factor to the dielectric substrate 102, while the L-glass fabric enables the Coefficient of Thermal Expansion (CTE) in the x-y plane of the dielectric substrate 102 to match the CTE of the conductive plating 104. An additive material 112 capable of absorbing Ultraviolet (UV) light (e.g., light having a wavelength of 180nm to 400 nm) is dispersed in the perfluorocopolymer matrix 110. The presence of the UV responsive additive material 112 enables the flexible laminate 100 to be drilled by a UV laser, for example, for forming circuit structures such as vias through the thickness of the flexible laminate 100.

The flexible laminate 100 is a planar structure having a thickness along the z-axis of less than about 200 μm or less than about 100 μm, such as 20 μm to 200 μm, such as 30 μm to 90 μm or 30 μm to 60 μm. The thickness of the dielectric substrate 102 constitutes a majority of the thickness of the flexible laminate 100. For example, the dielectric substrate 102 has a thickness along the z-axis of less than about 200 μm or less than about 100 μm, such as 20 μm to 200 μm, such as 30 μm to 90 μm or 30 μm to 60 μm. Each conductive plating 104a, 104b has a thickness along the z-axis of less than about 72 μm, such as less than about 18 μm, such as 5 μm to 18 μm.

The dielectric substrate 102 of the flexible laminate 100 has a low dielectric constant, such as a dielectric constant of less than about 2.7, such as 2.1 to 2.4, at 10 GHz. The dielectric constant has a thermal coefficient having a value of-250 ppm/°c to 50ppm/°c, such as-100 ppm/°c to 50ppm/°c or-50 ppm/°c to 25ppm/°c, over a temperature range of 0 ℃ to 100 ℃. The dielectric substrate 102 also has a low dissipation factor, e.g., a dissipation factor of less than 0.0015, such as less than 0.001 or less than 0.0008, e.g., 0.0002 to 0.001, e.g., 0.0006 to 0.0008, at 10 GHz.

The improved electrical properties (e.g., low dielectric constant and low dissipation factor) of the flexible laminate 100 enable designers to achieve improvements in insertion loss, e.g., up to 25% or more for a given characteristic impedance relative to existing flexible materials. It is believed that low levels of ferromagnetic elements (e.g., fe, ni, or Co) in the conductive plating 104 (e.g., in copper foil) may help achieve low insertion loss.

The Coefficient of Thermal Expansion (CTE) of the dielectric substrate 102 and the CTE of the conductive plating 104 are similar in the x-y plane of the flexible laminate 100. For example, when the conductive plating 104 is copper foil, the CTE in the x-y plane of the dielectric substrate 102 may be 5ppm/°c to 25ppm/°c, such as 16ppm/°c to 22ppm/°c, such as 14ppm/°c to 20ppm/°c. The matching of CTE values between the dielectric substrate 102 and the conductive plating 104 provides dimensional stability to the flexible laminate 100, such as less than about 0.1%, for example, such that the flexible laminate maintains its original dimensions within about 0.1% when subjected to removal of the conductive plating and temperature changes.

The conductive plating 104 of the flexible laminate 100 adheres strongly to the dielectric substrate. For example, the peel strength between the dielectric substrate 102 and the conductive plating 104 is greater than 2 lbs/inch, such as greater than 4 lbs/inch, such as 2 lbs/inch to 20 lbs/inch or 4 lbs/inch to 20 lbs/inch. The flexible laminate 100 is mechanically robust to bending and can bend over the bending radius typically found in electronic devices without disabling any of the components of the flexible laminate 100. This flexibility facilitates the installation of the flexible laminate 100 into a device.

The flexible laminate 100 may be drilled by UV laser and compatible with metallization techniques (e.g., plasma metallization) such that vias may be formed through the thickness of the flexible laminate 100 (e.g., along the z-axis of the flexible laminate 100). The dielectric substrate 102 of the flexible laminate 100 has a float resistance at 288 ℃ of at least 5 seconds, at least 10 seconds, at least 30 seconds, or at least 60 seconds, such as 5 seconds to 20 seconds, 10 seconds to 15 seconds, 10 seconds to 30 seconds, 10 seconds to 60 seconds, or 30 seconds to 60 seconds.

The flexible laminate 100 may be used in printed wiring boards, such as in flexible printed circuit board antennas. For example, the size and electrical properties of the flexible laminate 100 may make the flexible laminate 100 suitable for high frequency applications, such as antennas for mobile devices that may be used on 5G communication networks, as discussed further below, or for use with automotive radar or other high frequency applications. In some examples, the plurality of flexible laminates 100 may themselves be laminated into a multi-layer circuit board structure. The flexible laminate is substantially void-free and resistant to the formation of conductive anode wires, which contributes to the electrical reliability of the flexible laminate as a printed wiring board substrate.

The low dielectric constant and low dissipation factor of the dielectric substrate 102 of the flexible laminate 100 is due, at least in part, to the composition of the perfluorocopolymer matrix 110. The perfluorocopolymer matrix 110 comprises a fluorinated perfluorocopolymer, such as a fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer, and a non-fluorinated perfluorocopolymer, such as a non-fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer. The fluorinated perfluorinated copolymer, non-fluorinated perfluorinated copolymer, or both may be linear, non-branched polymers. Fluorinated perfluorinated copolymers have low or zero polarity and therefore have low dielectric constants and low dissipation factors. However, fluorinated perfluorinated copolymers are generally non-reactive, e.g., fluorinated copolymers have poor adhesion to the L-glass fabric 108 and the conductive coating 104. The non-fluorinated perfluorinated copolymer has reactive end groups (e.g., carboxyl or amide end groups) that are attracted to the L-glass fabric 108 and the conductive coating 104. The presence of these reactive end groups promotes adhesion between the perfluorocopolymer matrix and the L-glass fabric 108 and the conductive coating 104.

In some examples, the perfluorocopolymer is prepared by water-dispersion polymerization, and may contain at least about 400 reactive end groups per 10 ⁶ carbon atoms after polymerization. Most of these end groups are thermally unstable in the sense that they may undergo chemical reactions (such as decomposition and decarboxylation) when exposed to heat (such as that encountered during extrusion and film formation) or film lamination conditions, discoloring the extruded polymer or filling the polymer with heterogeneous gas bubbles, or both. To prepare the fluorinated perfluorinated copolymers described herein, the polymerized perfluorinated copolymers are stabilized to replace substantially all of the reactive end groups with thermally stable-CF 3 end groups. An exemplary method of stabilization is to expose the fluoropolymer to a fluorinating agent (such as elemental fluorine), for example by a method as disclosed in U.S. Pat. No. 4,742,122 and U.S. Pat. No. 4,743,658, the contents of which are incorporated herein by reference in their entirety.

Non-fluorinated perfluorinated copolymers generally have higher dissipation factors than fluorinated perfluorinated copolymers. The composition of the perfluorocopolymer matrix 110 can be tailored to achieve a sufficiently low dielectric constant and low dissipation factor of the dielectric substrate 102 and sufficient adhesion to the L-glass fabric 108 and the conductive plating 104. For example, the composition of the perfluorocopolymer matrix 110 can be adjusted to provide as much fluorinated copolymer as possible while still maintaining adequate adhesion to the L-glass fabric 108 and the conductive coating 104. A sufficiently low dielectric constant of the dielectric substrate 102 is a dielectric constant of less than about 2.7, such as 2.1 to 2.4, at 10 GHz. A sufficiently low dissipation factor of the dielectric substrate 102 is a dissipation factor of less than 0.0015, such as 0.0002 to 0.001, e.g., 0.0006 to 0.0008, at 10 GHz. In some examples, the adequacy of adhesion between the perfluorinated copolymer matrix 110 and the L-glass fabric 108 and the conductive plating 104 is determined by the peel strength between the dielectric substrate 102 and the conductive plating 104. For example, if the peel strength is greater than 2 lbs/inch, such as greater than 4 lbs/inch, such as 2 lbs/inch to 20 lbs/inch or 4 lbs/inch to 20 lbs/inch, the adhesion is sufficient. In some examples, the adequacy of adhesion between the perfluorocopolymer matrix 110 and the L-glass fabric 108 and the conductive plating layer 104 is determined by the propensity of the flexible laminate 100 to resist the formation of Conductive Anodic Filaments (CAF), which will be discussed further below.

In some examples, the composition of the perfluorocopolymer matrix 110 is indicated by the ratio (e.g., weight or volume) of fluorinated perfluorocopolymer to non-fluorinated perfluorocopolymer. The weight percent of fluorinated perfluorinated copolymer may be 50% to 90%, such as 50% to 80%, e.g., 50%, 60%, 70%, 75%, 80% or 90%, and the weight percent of non-fluorinated perfluorinated copolymer may be 10% to 50%, e.g., 10%, 20%, 25%, 30%, 40% or 50%.

In some examples, the composition of the perfluorocopolymer matrix 110 is indicated by the number (e.g., number concentration) of carboxyl end groups present in the perfluorocopolymer matrix 110. Non-limiting examples of such carboxyl end groups include-COF, -CONH ₂、-CO₂CH₃, and-CO ₂ H, and are determined by polymerization aspects such as choice of polymerization medium, initiator, chain transfer agent (if any) and buffer (if any). The number of carboxyl end groups per million carbon atoms present in the perfluorocopolymer matrix 100 can be from 30 to 70, such as from 35 to 65. The number of carboxyl end groups can be selected to achieve sufficient adhesion between the perfluorocopolymer substrate 110 and the L-glass fabric 108 and conductive coating 104, while also achieving a sufficiently low dielectric constant and dissipation factor. For example, the number of carboxyl end groups may be selected such that CAF is not formed in the flexible laminate 100. In some examples, the composition of the fluorinated and non-fluorinated perfluorocopolymers is indicated by the number (e.g., number concentration) of carboxyl end groups present in each type of perfluorocopolymer. The fluorinated perfluorocopolymer may have less than 10 carboxyl end groups per million carbon atoms, for example 5 or less, or1 or less, or less than 1 carboxyl end group. The non-fluorinated perfluorinated copolymers may have 100 to 300 carboxyl end groups per million carbon atoms, for example 120 to 280 or 150 to 250 carboxyl end groups per million carbon atoms. Analysis and quantification of carboxyl end groups in the perfluorocopolymer can be performed by infrared spectroscopy, such as described in U.S. Pat. No. 3,085,083, U.S. Pat. No. 4,742,122, and U.S. Pat. No. 4,743,658, the contents of all of which are incorporated herein by reference in their entirety. The presence of thermally stable end groups-CF 3 (fluorinated product) is inferred from the absence of unstable end groups after fluorine treatment. The presence of-CF 3 end groups results in a decrease in dissipation factor of the perfluorocopolymer compared to other end groups.

The Melt Flow Rate (MFR) of the fluorinated perfluorinated copolymer, the non-fluorinated perfluorinated copolymer, or both may also affect the adhesion between the perfluorinated copolymer matrix 110 and the L-glass fabric 108 and the conductive plating 104. Polymers with high MFR flow more readily during lamination of the flexible laminate 100 than polymers with lower MFR. The flow of the perfluorocopolymer matrix 110 during the lamination process (discussed in more detail below) enables the perfluorocopolymer matrix 110 to completely encapsulate the fibers of the L-glass fabric 108, thereby creating a dielectric substrate 102 that is substantially void-free (e.g., non-porous). The void-free dielectric substrate 102 resists CAF formation. For example, the MFR of the fluorinated perfluoro copolymer may be from 1 g/10 min to 40 g/10 min, such as from 2 g/10 min to 15 g/10 min, such as 2 g/10 min, 4 g/10 min, 6 g/10 min, 8 g/10 min, 10 g/10 min, 12 g/10 min, 14 g/10 min, 16 g/10 min, 18 g/10 min, 20 g/10 min, 25 g/10 min, 30 g/10 min, 35 g/10 min or 40 g/10 min. The MFR of the non-fluorinated perfluoro copolymer may be from 1 g/10 min to 40 g/10 min, such as from 2 g/10 min to 20 g/10 min, such as 2 g/10 min, 5 g/10 min, 10 g/10 min, 15 g/10 min or 20 g/10 min. The fluorinated and non-fluorinated perfluorinated copolymers may be provided in a ratio that results in a total MFR of the perfluorinated copolymer matrix of 10 g/10 min to 30 g/10 min, e.g. 10 g/10 min, 15 g/10 min, 18 g/10 min, 21 g/10 min, 24 g/10 min, 27 g/10 min or 30 g/10 min.

Suitable materials for the fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) perfluoro copolymer include Teflon ^TM Perfluoroalkane (PFA) 416HP having an MFR of about 40 g/10 min or Teflon ^TM PFA 440HP (A/B) having an MFR of about 16 g/10 min or 14 g/10 min, respectively (The Chemours Company, wilmington, DE). Suitable materials for the non-fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) include Teflon ^TM PFA 316 having an MFR of about 40 g/10 min or Teflon ^TM PFA 340 (Chemours) having an MFR of about 14 g/10 min.

The fluorinated perfluorinated copolymer, the non-fluorinated perfluorinated copolymer, or both have a high melting point, such as 250 ℃ to 350 ℃, e.g., 280 ℃ to 320 ℃, 290 ℃ to 310 ℃, e.g., about 305 ℃. The high melting point of the fluorinated perfluorinated copolymer, non-fluorinated perfluorinated copolymer, or both results in the perfluorinated copolymer matrix 100 being resistant to high temperatures and provides sufficient solder float resistance to the dielectric substrate 102, such as solder float resistance at 288 ℃ of at least 5 seconds, at least 10 seconds, at least 30 seconds, or at least 60 seconds, e.g., 5 seconds to 20 seconds, 10 to 15 seconds, 10 seconds to 30 seconds, 10 seconds to 60 seconds, or 30 seconds to 60 seconds, measured according to the IPC-TM-650 test method.

The composition of the perfluorocopolymer matrix 110 can be selected to enable the dielectric substrate 102 to be compatible with plasma processing, for example, for metallization of vias formed through the thickness of the flexible laminate 100.

Specific examples of fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymers suitable for inclusion in the perfluoro copolymer matrix 100 include Teflon ^TM Perfluoroalkane (PFA) 416HP having an MFR of about 40 g/10 min or Teflon ^TM PFA 440HP (The Chemours Company, wilmington, DE) having an MFR of about 14 g/10 min. Specific examples of non-fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymers suitable for inclusion in the perfluoro copolymer matrix 100 include Teflon ^TM PFA 316 having an MFR of about 40 g/10 min or Teflon ^TM PFA 340 (The Chemours Company) having an MFR of about 14 g/10 min.

In some examples, the perfluorocopolymer matrix 100 is formed from a single type of perfluorocopolymer having both fluorinated and reactive end groups (e.g., rather than a mixture of fluorinated and non-fluorinated perfluorocopolymers). The ratio of fluorinated end groups to reactive end groups in the single type of perfluorocopolymer is selected to achieve sufficient adhesion between the perfluorocopolymer substrate 110 and the L-glass fabric 108, as well as a sufficiently low dielectric constant and dissipation factor.

The presence of the woven L-glass fabric 108 enables the CTE of the dielectric substrate 102 to be matched to the CTE of the metal foil 104. The woven L-glass fabric 108 embedded in the perfluorocopolymer matrix 110 is formed from bundles of polarized glass (e.g., L-glass).

The composition of the L-glass is shown in Table 1. The composition of the E-glass is also shown for comparison. The L-glass has a CTE lower than that of the perfluorocopolymer matrix 110, such as a CTE of 2.5ppm/°c to 4ppm/°c, e.g., 2.5ppm/°c to 3ppm/°c or 3ppm/°c to 4ppm/°c. By adjusting the ratio of the perfluorocopolymer matrix 110 to the woven glass fabric 108, the CTE of the dielectric substrate 102 in the x-y plane can be matched to the in-plane CTE of the metal foil 104, thereby providing dimensional stability to the flexible laminate 100. For example, the dielectric substrate 102 may include 5 to 20 volume percent of the woven L-glass fabric 108 and 80 to 95 volume percent of the perfluorocopolymer matrix 110 and the woven glass fabric 108. The CTE in the x-y plane of the dielectric substrate 102 may be 5ppm/°c to 25ppm/°c, e.g., 16ppm/°c to 22ppm/°c, e.g., 14ppm/°c to 20ppm/°c, thereby providing dimensional stability of less than about 0.1%. Conversely, the CTE of the perfluorocopolymer matrix 110 alone can be from 100ppm/°c to 300ppm/°c.

	L-glass	E-glass
			SiO₂	52-56%	52-56%
CaO	0-10%	20-25%
			Al₂O₃	10-15%	12-16%
B₂O₃	15-20%	5-10%
			MgO	0-5%	0-5%
Na₂O,K₂O	0-1%	0-1%
			TiO₂,LiO₂	0-5%	0%

TABLE 1 composition of L-glass

L-glass has a low dielectric constant, such as a dielectric constant of 4.0 to 5.0, e.g., 4.5 to 5.0 or 4.5 to 4.8 at 10 GHz. Thus, the dielectric substrate 102 has a low dielectric constant and low loss even in the presence of the L-glass fabric embedded in the perfluorocopolymer matrix. L-glass also has a low dissipation factor, such as a dissipation factor of 0.002 to 0.003 at 10GHz, e.g., 0.002, 0.0023, 0.0025, 0.0028, or 0.003.

The woven L-glass fabric 108 has a thickness of less than about 100 μm, such as about 30 μm to 100 μm or 10 μm to 30 μm, thereby helping to achieve a thin dielectric substrate 102. The basis weight of the quartz fabric 108 is less than about 1000g/m ², such as less than about 50g/m ², such as 10g/m ² to 50g/m ². In one specific example, the L-glass fabric 108 is an NL1035 NL-glass fabric (ASAHI KASEI Corporation, tokyo, japan).

In some examples, the woven L-glass fabric 108 is subjected to one or more surface treatments to improve wettability of the perfluorinated copolymer matrix 110 with the fibers of the woven L-glass fabric 108, to remove residual organic matter, or to mechanically alter the surface of the fibers to enhance adhesion between the fibers of the L-glass fabric 108 and the perfluorinated copolymer matrix 110. The purpose of the surface treatment may be to promote substantially complete wetting of the L-glass fibers by the perfluorocopolymer such that the perfluorocopolymer completely encapsulates the L-glass fiber (e.g., L-glass yarn) bundles. The sufficient encapsulation and adhesion of the perfluorocopolymer to the L-glass fiber bundles enables the dielectric substrate 102 to be substantially void-free (e.g., non-porous), which in turn helps to prevent the formation of conductive anode filaments and electromigration from occurring during post-processing (e.g., during formation of vias through the thickness of the flexible laminate 100).

The surface treatment may include a heat treatment to remove residual organic matter (e.g., residual starch) from the surface of the L-glass fiber, such that a clean L-glass surface is exposed to the perfluorocopolymer. The surface treatment may include the addition of an adhesion promoter, such as a methacrylate silane, an aminosilane, or a fluorosilane, to the surface of the L-glass fiber. The surface treatment may include plasma treatment or corona treatment. The surface treatment may include treatment with a polymer coating, such as a fluoropolymer, for example, perfluoroalkane (PFA), fluorinated Ethylene Propylene (FEP), or Teflon ^TM amorphous fluoropolymer, to form a polymer (e.g., fluoropolymer) film on the surface of the L-glass fiber. For example, the L-glass fabric may be immersed in a solution containing the fluoropolymer dispersion to form a monolayer of the fluoropolymer on the surface of the L-glass fiber. The surface treatment may include treatment with a fluorinated silane to form a layer of fluorinated molecules, such as a monolayer, on the surface of the L-glass fiber. A combination of surface treatments, such as heat treatment, followed by plasma or corona treatment, may be applied. The surface treatment applied to the L-glass fabric 108 may improve the wettability of the perfluorocopolymer matrix 110 with respect to the fibers, enable the perfluorocopolymer matrix 110 to better encapsulate the fibers of the L-glass fabric 108, and enable greater adhesion between the perfluorocopolymer matrix 110 and the fibers of the L-glass fabric 108, thereby helping to form a void-free dielectric substrate 102 that resists CAF formation.

The wettability of the L-glass fabric can be characterized by the Water Contact Angle (WCA). The surface treated woven L-glass fabric may have a WCA of 0 ° to 60 °.

In some examples, the laminate structure may be designed to achieve good encapsulation of the L-glass fabric, for example, in addition to or instead of applying a surface treatment to the L-glass fabric. Referring to fig. 2, an exemplary metal clad flexible laminate may be manufactured by laminating a set of layers 150. The set of layers includes a multilayer fluoropolymer film including non-fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) layers 162a, 162b disposed on either side of the L-glass fabric 108, and a perfluorocopolymer layer 164a, 164b comprising fluorinated perfluorocopolymer and non-fluorinated perfluorocopolymer disposed on the outward facing side of each non-fluorinated layer 162. A conductive plating layer, such as the metal (e.g., copper) foil 104a, 104b described above, is disposed on both outer sides of the set of layers 150. When the structure shown in fig. 2 is laminated to produce a flexible laminate (see further discussion of the lamination process below), the non-fluorinated layer 162 encapsulates the L-glass fabric 108 such that the non-fluorinated layer 162 and the perfluorinated copolymer layer 164 form a matrix in which the L-glass fabric 108 is embedded, for example forming a dielectric substrate for the flexible laminate.

Referring again to fig. 1, the additive material 112 is dispersed (e.g., uniformly dispersed) in the perfluorocopolymer matrix 110. The additive material 112 is a material capable of absorbing UV light such that the flexible laminate 100 may be treated by a UV drilling process, for example, to form vias between the top and bottom surfaces 106 of the flexible laminate 100. The additive material 112 is present in the dielectric substrate 102 at a volume percent of less than 2%, such as1 volume percent to 2 volume percent, such as1 volume percent, 1.25 volume percent, 1.5 volume percent, or 2 volume percent. The additive material 112 may be a material having a relatively low dielectric constant (e.g., a dielectric constant of 10 to 1000) such that inclusion of the additive material 112 in the perfluorocopolymer matrix 110 does not significantly increase the dielectric constant or dissipation factor of the dielectric substrate 102. For example, inclusion of less than 2% by volume of the additive material 112 may result in an increase in the dielectric constant of the dielectric substrate 102 of less than 10%, such as less than 5% or less than 2%.

In some examples, the additive material 112 is an inorganic particle, such as a particle of cerium oxide (CeO ₂), titanium dioxide (TiO ₂), silicon dioxide (SiO ₂), barium titanate (BaTiO ₃), calcium titanate (CaTiO ₃), zinc oxide (ZnO), or other suitable material. The particles may have a diameter of less than about 5 μm, less than about 2 μm, less than about 1 μm, or less than about 0.5 μm, for example, 0.1 μm to 0.5 μm. For example, smaller particles are typically more effective UV light absorbers than larger particles of similar composition. In some examples, the additive material 112 is an organic (e.g., polymer) additive, such as a low loss thermoset material, such as polyimide, blended into the perfluorocopolymer matrix 110. In some examples, both inorganic particles and organic additives are used as additive materials.

The copper foil 104 of the flexible laminate 100 provides a platform on which conductive patterns may be defined, for example, so that the flexible laminate 100 may be used as a printed wiring board. In some examples, the copper foil 104 is disposed on the surface 106 of the dielectric substrate 102 by a mechanical process (e.g., a roll-to-roll lamination process). For example, the copper foil may be an electrodeposited copper foil or a rolled copper foil. In some examples, the copper foil 104 is deposited (e.g., electrolytic plated) onto the dielectric substrate 102.

The copper foil 104 has a thickness of less than about 72 μm, such as less than about 18 μm, such as 10 μm to 18 μm. The copper foil 104 has a low Root Mean Square (RMS) roughness, such as an RMS roughness of less than 1 μm, e.g., less than 0.5 μm, as measured by non-contact interferometry. The low RMS roughness of the copper foil 104 helps to maintain low insertion loss of the circuit made from the flexible laminate 100. In some examples, the RMS roughness of the copper foil 104 is selected to balance a low insertion loss (e.g., achievable by a low RMS roughness) with good adhesion between the copper foil 104 and the dielectric substrate 102 (e.g., achievable by a higher RMS roughness). For example, as discussed above, a sufficiently high peel strength between the dielectric substrate 102 and the copper foil 104 is a peel strength of greater than 2 lbs/inch, such as greater than 4 lbs/inch, such as 2 lbs/inch to 20 lbs/inch or 4 lbs/inch to 20 lbs/inch.

The copper foil 104 has a purity of at least about 99.9%. The surface chemistry of the copper foil 104 may be affected by surface treatments such as zinc treatment, thermal stability additive treatment, and oxidation resistance treatment. These surface treatments may be applied to one or both surfaces of the copper foil 104. Elements such as iron and zinc have been found to be effective in improving peel strength without significantly degrading the electrical properties of the substrate.

As discussed above, the dielectric substrate 102 of the flexible laminate 100 is substantially void free and has sufficient adhesion between the perfluorocopolymer matrix 110 and the L-glass fabric 108 that the flexible laminate is resistant to the formation of Conductive Anode Filaments (CAF). CAF is a metal wire formed in, for example, a void or weak area of a dielectric substrate due to electromigration of the metal, for example, by application of an electric field. For example, when CAF creates a short circuit path between vias through a printed wiring board, CAF formation may lead to electrical failure. When the resistance drops less than ten times throughout the test duration, i.e. the resistance is greater than 10 megaohms after an initial 96 hour equilibration period, the flexible laminate may be considered to not form CAF. For example, CAF testing may last for up to 1000 hours or more, with voltages of 100VDC to 1000VDC applied, depending on the application standard.

An example of CAF formation is shown in fig. 3A. Fig. 3A shows a hypothetical laminate 200 having a dielectric matrix 202 with glass fibers 204 embedded therein. A via (sometimes also referred to as a via) 206 is formed through the thickness of the laminate 200 and is plated with a metal 208, such as copper. Application of the electric field causes anodic dissolution, migration, and redeposition of the metal 208 in the dielectric matrix 202, for example at the interface between the dielectric matrix 202 and the glass fibers 204, thereby forming filaments 210 extending between adjacent vias 206.

Fig. 3B shows another example of CAF formation in a hypothetical laminate 250 having a dielectric matrix 252 with glass fibers 254 embedded therein and conductor patterns 262 (e.g., copper patterns) defined on the top, bottom, and interior surfaces of the laminate 250. A metal (e.g., copper) wire 260 is formed at the interface between the conductor pattern 262 and the glass fiber 254.

Referring again to fig. 1, the dielectric substrate 102 of the flexible laminate is substantially void-free and has strong adhesion between the perfluorocopolymer matrix 110 and the L-glass fabric 108. This is achieved, for example, by the nature of the perfluorocopolymer (e.g., the number concentration of reactive end groups), the surface chemistry of the L-glass fabric, and manufacturing parameters such as pressure and temperature (discussed below). In addition, the arrangement of the L-glass fabric 108 in the perfluorocopolymer matrix 110 is such that there is substantially no contact between the fibers of the fabric and the conductive coating 104. Thus, CAF formation in the dielectric substrate 102 is minimal and the flexible laminate 100 can be used as a reliable and robust printed wiring board substrate.

Referring to fig. 4, a multi-layered printed wiring board 300 may be formed of a plurality of the above-described flexible laminates 100. In the example of fig. 4, the multilayer printed wiring board 300 includes two flexible laminates 100a, 100b connected by an adhesive layer 302. Vias (also referred to as through holes; not shown) through all or part of the thickness of the multilayer printed wiring board may be defined, for example, by UV drilling, wherein UV energy is absorbed by additive materials in the dielectric substrate of the flexible laminate 100. The vias may be plated with a metal, such as a copper film. The adhesive layer 302 may be, for example, an adhesive that is bondable at a temperature below the melting point of the perfluorocopolymer matrix of the flexible laminate 100. In some examples, the adhesive is a thermoplastic adhesive capable of bonding at a temperature from 0 ℃ to 50 ℃ below the melting point of the perfluorocopolymer matrix. In some examples, the adhesive is a thermoset adhesive that is capable of bonding at a temperature from 0 ℃ to 200 ℃ below the melting point of the perfluorocopolymer matrix, for example, at a temperature from 150 ℃ to 250 ℃.

Referring to fig. 5, a plurality of (here, three) flexible laminates 100 are laminated together to form a multilayer printed wiring board 400. The central flexible laminate 100c includes a top conductive plating and a bottom conductive plating. The flexible laminates 100d, 100e each include a single conductive plating. The flexible laminates 100c, 100d are bonded to the central flexible laminate 100e by adhesive layers 402a, 402b, respectively. The adhesive layers 402a, 402b may be, for example, adhesives that can bond at a temperature below the melting point of the perfluorocopolymer matrix of the flexible laminate 100. In some examples, the adhesive is a thermoplastic adhesive capable of bonding at a temperature from 0 ℃ to 50 ℃ below the melting point of the perfluorocopolymer matrix. In some examples, the adhesive is a thermosetting adhesive that is capable of bonding at a temperature from 0 ℃ to 200 ℃ below the melting point of the perfluorocopolymer matrix.

Vias (not shown) may be defined through all or a portion of the thickness of the multilayer printed wiring board 400, for example, by UV drilling.

The printed wiring board made from the flexible laminate 100 described herein may be used in a variety of applications, for example, high frequency applications, such as high frequency communications applications. For example, referring to fig. 6, a printed wiring board 502 comprising one or more flexible laminates may be used for an antenna or antenna feed of a communication device 500 (e.g., a mobile communication device) operable on a 5G communication network. For example, flexible laminates may be used as substrates for printed wiring boards for antennas or antenna feeds of communication devices to connect electronic components of the devices that lie on different planes. The printed wiring board 504 comprising one or more flexible laminates may be used in a communication network device, such as a transmitting antenna in a tower 508 of a cellular communication network. Printed wiring boards including flexible laminates may also be used in other applications, such as in camera feeders in mobile computing devices.

The flexible laminates described herein may be manufactured by a lamination process. Referring to fig. 7, in one example, an L-glass fabric 108 is disposed between two perfluorocopolymer membranes 120a, 120 b. Each of the perfluorocopolymer membranes 120a, 120b has a thickness of 10 μm to 100 μm, for example 10 μm to 80 μm, 10 μm to 60 μm, or 20 μm to 50 μm. The conductive plating layers 104a, 104b are provided on the perfluorocopolymer films 120a, 120b, respectively. For example, the conductive plating 104 is an electrodeposited copper foil or a roll annealed copper foil. Each conductive plating 104a, 104b has a thickness of less than about 72 μm, such as less than about 18 μm, such as 10 μm to 18 μm.

The layers of material 104, 108, 120 are heated and compressed to consolidate the layers of material to form the flexible laminate 100. In some examples, in a second processing step, the L-glass fabric 108 and the two perfluorocopolymer films 120a, 120b are laminated to form a dielectric substrate, and a conductive plating (e.g., copper foil) is electrodeposited onto the dielectric substrate.

The parameters of the lamination process (e.g., temperature, time, and pressure) are selected to achieve a target viscosity of the perfluorocopolymer that enables the perfluorocopolymer to flow, thereby wetting and encapsulating the glass strands of the L-glass fabric 108 and enabling good adhesion between the perfluorocopolymer and the conductive coating 104. For example, the process parameters are selected such that the perfluorocopolymer achieves a zero shear viscosity of 2000Pa-s to 5000Pa-s at 330 ℃. The temperature may be higher than the melting point of the perfluorocopolymer, for example, 10 ℃ to 30 ℃ higher than the melting point of the perfluorocopolymer. For example, the temperature may be 300 ℃ to 400 ℃, such as 320 ℃ to 330 ℃, such as 300 ℃, 320 ℃, 340 ℃, 360 ℃, 380 ℃, or 400 ℃. The rate of temperature increase may be 1 ℃ per minute to 5 ℃ per minute, for example 1 ℃,2 ℃,3 ℃,4 ℃, or 4 ℃. The pressure applied to the layer of material may be 100psi to 1000psi, such as 200psi to 1000psi or 600psi to 1000psi. Dwell times (e.g., for static lamination processes) may be 30 minutes to 120 minutes, such as 30 minutes, 60 minutes, 90 minutes, or 120 minutes.

Fig. 7 depicts an isobaric roll-to-roll lamination process using a set of rolls 600. In some examples, the roll-to-roll lamination process is an isovolumetric gap controlled lamination process. In some examples, the lamination process is a static lamination process in which the material layers are pressed between heated platens.

The perfluorocopolymer film 120 is formed by, for example, melt processing and extrusion. In some examples, the additive material is mixed into the molten fluorinated perfluorinated copolymer, and the mixture of fluorinated copolymer and additive material is mixed with the molten non-fluorinated perfluorinated copolymer. In some examples, the additive material is mixed into the molten non-fluorinated perfluorinated copolymer, and the mixture of non-fluorinated perfluorinated copolymer and additive material is mixed with the molten fluorinated perfluorinated copolymer. The resulting perfluorocopolymer mixture is extruded to form a perfluorocopolymer film. Mixing the additive material with the non-fluorinated perfluoropolymer aids in the integration and dispersion of the additive material throughout the perfluorocopolymer film.

Fig. 8 is a flow chart of an exemplary process for manufacturing the flexible laminate 100. An additive material capable of absorbing ultraviolet light is dispersed in a non-fluorinated perfluoro copolymer, such as a non-fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) perfluoro copolymer (700). The additive material is, for example, particles of cerium oxide, titanium dioxide, silicon dioxide, barium titanate, calcium titanate or zinc oxide, or a polymeric additive such as polyimide. The non-fluorinated perfluorocopolymer with dispersed additive material is mixed (702) with a fluorinated perfluorocopolymer, such as a fluorinated tetrafluoroethylene/perfluoro (alkyl vinyl ether) perfluorocopolymer, to form a perfluorocopolymer mixture. The perfluorocopolymer mixture is melt processed and extruded to form a perfluorocopolymer film (704).

The woven L-glass fabric is exposed to a surface treatment, such as heat treatment, corona or plasma treatment, or a coating is formed on the surface of the fibers of the L-glass fabric (706). The copper foil, e.g., electrodeposited copper foil or calendered annealed copper foil, is also exposed to a surface treatment, such as a heat treatment, corona or plasma treatment, or deposition of an adhesion promoter or thermal stability additive (708).

A layered stack (710) of material is formed comprising a treated L-glass fabric disposed between two perfluorocopolymer films with a treated conductive plating on both the top and bottom of the stack. For example, in a static lamination process or a roll-to-roll lamination process, a layered stack of materials is laminated by the application of heat and pressure to form a flexible laminate (712).

Examples

The following polymers and polymer dispersions were used in these examples.

PFA1 Teflon ^TM PFA 440HP (A/B) (Chemours), a high purity fluorinated Perfluoroalkoxy (PFA) melt processable resin having MFR of 16g/10min (for "A") and 14g/10min (for "B").

PFA2 Teflon ^TM PFA 340 (Chemours), a common non-fluorinated PFA melt processible resin, has an MFR of 14g/10 min.

PFA3 Teflon ^TM PFA 416HP (Chemours), high purity fluorinated PFA melt processible resin, has an MFR of 40g/10 min.

Example 1 mechanical characterization of flexible copper clad laminates containing L-glass or Quartz fabrics

Experiments were performed to investigate the thickness, flatness and dimensional stability of copper clad laminates incorporating L-glass fabric and quartz fabric. The PFA film was combined with NL1035 NL-glass fabric from Asahi or 1027C-04 quartz fabric from Shin-Etsu and a 12 μm thick BHFX-P92F-HG calendered copper foil from JX Nippon Mining & Metals Corporation (Tokyo, japan) to form a flexible copper clad laminate. The PFA film consisted of 50 wt% PFA1, 25 wt% PFA2 and 22.5 wt% PFA3, and 2.5 wt% TiO2 particles (50.63 vol% PFA1, 25.31 vol% PFA2 and 22.78 vol% PFA3, and 1.28 vol% TiO2 particles) and was treated with corona treatment on both sides of the film. The material was laminated in a hot oil vacuum press at a peak temperature of 320 ℃ and a pressure of 200 psi.

Details of experimental configurations including the materials used are shown in table 2. The five values in the "build" column refer to the thickness of the copper plating on each side of the laminate (12 μm in this example), the thickness of the perfluorocopolymer film used to make the laminate (54 μm in this example), and the type of fabric (NL 1035L-glass or 1035 quartz glass fabric in this example). The material was laminated in a hot oil vacuum press at a dwell temperature of 320 ℃ and a pressure of 200psi with a dwell time of 60 minutes, a vacuum of 1atm, and a ramp rate of 2 ℃ per minute. The samples were equilibrated at 23 ℃ and 50% relative humidity for 24 hours prior to testing.

Table 2. Experimental details.

The laminate is shown in the photograph of fig. 9. The planarity of each laminate was visually characterized. As can be seen from fig. 9, the laminate comprising L-glass fabric is flatter than the laminate comprising quartz fabric.

The thickness of each laminate was measured after etching according to IPC TM-650 2.2.18 test method, and the results are shown in fig. 10. Generally, the L-glass laminate is thicker than the quartz glass laminate. The thickness and estimated flash results are shown in table 3. The estimated flash (squeeze-out) was measured by measuring the film flow distance from the edge of the platen at the time of extrusion. The resin content of each laminate is shown in fig. 11.

Table 3 experimental test data of the experiment are detailed in table 2.

The dimensional stability results of the laminates tested in the Machine Direction (MD) and cross direction (CMD) are shown in FIG. 12A (tested according to IPC TM-650.2.4B) and FIG. 12B (tested according to IPC TM-6502.2.4 c). These results show that the dimensional stability value of the L-glass laminate is lower than that of the quartz glass laminate.

Example 2 characterization of flexible copper clad laminates containing L-glass or Quartz fabrics

Additional experiments were performed to investigate the relationship between thickness and flatness and dimensional stability. Various types of PFA films were combined with various types of glass fabrics, including 1017C-02, 1027C-04, 1035C-04, 1078C-04, or 2116C-04 quartz fabrics from Shin-Etsu, or NL1027, NL1035, NL-1078, or L2-1078L-glass fabrics or NL-glass fabrics from Asahi. The PFA film and glass cloth were laminated with a 12 μm thick BHFX-P92F-HG calendered copper foil from JX Nippon Mining & Metals Corporation to form a flexible copper clad laminate. In some cases, R101 titanium dioxide particles (Chemours) were added at a filler loading of 1.25% by volume. The material was laminated in a hot oil vacuum press at a peak temperature of 320 ℃ and a pressure of 200psi with a dwell time of 60 minutes, a vacuum of 1atm, and a ramp rate of 2 ℃ per minute.

● Various PFA films were tested, including the following:

● PFA film 1, consisting of 50 wt% PFA1, 25 wt% PFA2 and 22.5 wt% PFA3 and 2.5 wt% TiO ₂ particles (50.63 vol% PFA1, 25.31 vol% PFA2 and 22.78 vol% PFA3 and 1.28 vol% TiO ₂ particles), was corona treated on both sides of the film.

● PFA film 2, consisting of 75 wt% PFA3 and 25 wt% PFA 2, was mixed with 2.5 wt% (1.25 vol%) R101 TiO ₂ particles.

Table 4. Experimental details.

The data obtained from these experiments are shown in figures 13-17. Fig. 13 is a graph of a visual representation of the flatness of each laminate, with a score of 1 being lowest (worst flatness) and 5 being optimal (very flat). FIG. 14 is a graph of the thickness of each laminate measured after etching according to the IPC TM-650.2.2.18 test method. These results indicate that generally thicker laminates are flatter than thinner laminates. Fig. 15 is a graph of the resin content of each laminate.

The dielectric constant and dissipation factor of each sample were also measured. The dielectric constant and dissipation factor were measured at 23℃and 50% relative humidity according to the IPC TM-650 2.5.5.13 test method. The results are shown in fig. 16 and 17. Dimensional stability results according to methods B and C are shown in fig. 18A and 18B.

These results show the effect of the L-glass fabric and the quartz glass fabric on the dielectric constant and dissipation factor of the laminate for the same resin content.

EXAMPLE 3 Effect of end group content on copper clad laminate

The effect of end group content on the properties of the copper clad laminate was evaluated by preparing PFA1 (fluorinated PFA) and PFA2 (non-fluorinated PFA) resins in combination with R101 titanium dioxide (Chemours) at various ratios of PFA2 to PFA 1. About 70 grams of the resin mixture was dry blended and then fed into a Rheometer Services inc. System 10 batch mixer equipped with a 60cc volume mixing bowl containing a roller blade. These blends were mixed at 150rpm for 10 minutes at 350 ℃ to disperse all components. The mixture was then removed from the bowl and subsequently pressed at 350 ℃ into a sheet having a thickness of about 100mm x about 0.20mm for electrical testing and subsequent lamination. The pressed film was tested and found to have the electrical properties shown in table 5:

Table 5. Electrical properties of molded PFA films with different PFA2 to PFA1 ratios at 10 GHz.

As expected, the dielectric constant (Dk) remained fairly consistent with PFA2 loading and the Dissipation Factor (DF) increased in a linear fashion with increasing PFA2 concentration in the blend.

Measurements were also made to determine the total number of carboxyl end groups per 10 ⁶ carbon atoms of the selected blend and the results are shown in table 6.

Load amount	PFA2 wt%	PFA1 wt%	TiO2 wt%	Carboxyl end group
					100%PFA2	97.50%	0.00%	2.50%	214
Polymer base	100%	0%
					75%PFA2	73.13%	24.38%	2.50%	178
Polymer base	75%	25%
					50%PFA2	48.75%	48.75%	2.50%	95
Polymer base	50%	50%
					25%PFA2	24.38%	73.13%	2.50%	53
Polymer base	25%	75%
					0%PFA2	0.00%	97.50%	2.50%	7
Polymer base	0%	100%

TABLE 6 end group levels of PFA blends with different 340 and 440 ratios

As with the dissipation factor data, it was found that adding PFA2 to the blend increased the amount of end groups measured in a generally linear fashion. A graph showing the measured dissipation factor as a function of end group level is shown in fig. 19. This was used to show how the level of end groups had a direct effect on the electrical behavior of the measured blend film.

These blended PFA films were combined with NL2116 fabric (ASAHI KASEI, japan) and 35 μm EXP-WS copper foil (Furukawa Electric co., ltd, japan) and laminated at 320 ℃ and 400psi for a dwell time of 60 minutes in an electro-thermal press (PHI, USA) to form copper clad laminates.

The experimental details are shown in tables 7A and 7B.

Run ID	Structure of the device	PFA film	Film MFR	Number of end groups
					G2-134-1	12/233/2116/224/12	100%PFA2	14.0	214.0
G2-134-2	12/216/2116/244/12	75%PFA2 /25%PFA1	14.0	178.3
					G2-134-3	12/222/2116/220/12	50%PFA2 /50%PFA1	14.0	95.0
G2-134-4	12/215/2116/220/12	25%PFA2 /75%PFA1	14.0	52.6
					G2-134-5	12/240/2116/213/12	15%PFA2 /85%PFA1	14.0	33.6
G2-134-6	12/207/2116/216/12	10%PFA2 /90%PFA1	14.0	22.8
					G2-134-7	12/219/2116/213/12	5%PFA2 /95%PFA1	14.0	12.0
G2-134-8	12/214/2116/210/12	100%PFA1	14.0	6.6

Table 7A. Experimental details.

Table 7B. Experimental details.

The laminates were tested for various properties. These results are shown in tables 8A and 8B.

Table 8a. Experimental test results of PFA2/PFA1 mixing study.

Table 8b experimental test results of PFA2/PFA1 mixing study.

A very good correlation was found between the total number of end groups per 10 ⁶ carbon atoms and the dissipation factor, and a suggested relationship between copper peel strength and end groups. These data can be seen in fig. 20 and 21.

EXAMPLE 4 Sharpie wicking behavior of commercially available laminates

In the Sharpie wicking test, holes are formed in a flexible laminate and rubbed around the edges of the holesThe pen was permanently marked and the hole was cleaned with isopropyl alcohol to remove excess ink. The radial distance from the edge of the hole to which the ink was wicked was measured. Without being bound by theory, it is believed that this wicking test serves as an indicator of adhesion between the fibers of the quartz fabric and the perfluorocopolymer matrix, and that poor adhesion or poor encapsulation leaves voids into which the ink can wick, resulting in longer travel distances. In contrast, a substrate with good adhesion and good encapsulation will exhibit a low wicking distance.

The Sharpie wicking test results of the laminates can predict the performance of the laminates under the CAF test. To demonstrate this correlation, sharpie wicking tests were performed on commercially available materials known to have good CAF resistance. The results of these tests are shown in table 9. These results indicate that a sharpie wicking result of less than 0.5mm corresponds to a material with good CAF resistance. Flexible copper clad laminates containing L-glass are believed to exhibit sharpie wicking of less than 1 mm.

Table 9 Sharpie wicking results for commercially available materials.

Specific embodiments of the present subject matter have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some implementations, multitasking and parallel processing may be advantageous.

Claims

1. A laminated product, comprising:

A dielectric substrate, the dielectric substrate comprising:

a perfluorocopolymer matrix comprising a fluorinated perfluorocopolymer and a non-fluorinated perfluorocopolymer;

L-glass fabric embedded in the perfluorocopolymer matrix; and

an additive material dispersed in the perfluorocopolymer matrix, wherein the additive material is capable of absorbing ultraviolet light; and

A conductive plating layer is disposed on a surface of the dielectric substrate.

2. The laminate according to claim 1, wherein the L-glass fabric comprises yarns of L-glass, NL-glass or L2-glass.

3 . The laminate according to claim 1 , wherein the laminate has a thickness of 20 μm to 200 μm.

4 . The laminate according to claim 3 , wherein the laminate has a thickness of 30 μm to 90 μm.

5 . The laminate according to claim 4 , wherein the laminate has a thickness of 30 μm to 60 μm.

6. A laminate according to any one of the preceding claims, wherein the dielectric substrate has a dielectric constant of 2.10 to 2.70 at 10 GHz.

7. The laminate according to claim 6, wherein the dielectric constant of the dielectric substrate is 2.10 to 2.40.

8. The laminate according to any one of the preceding claims, wherein the dielectric substrate has a thermal coefficient of dielectric constant with a value of -250 ppm/°C to +50 ppm/°C in the temperature range of 0°C to 100°C.

9. The laminate according to any one of the preceding claims, wherein the dielectric substrate has a dissipation factor of less than 0.0015 at 10 GHz.

10. The laminate of claim 9, wherein the dielectric substrate has a dissipation factor of 0.0006 to 0.001 at 10 GHz.

11. The laminate of claim 10, wherein the dielectric substrate has a dissipation factor of 0.0006 to 0.0008 at 10 GHz.

12. The laminate according to any one of the preceding claims, wherein the laminate has a planar shape defining an X-Y plane, and wherein the laminate has a coefficient of thermal expansion in the X-Y plane of 5 ppm/°C to 25 ppm/°C.

13. The laminate according to claim 12, wherein the coefficient of thermal expansion of the laminate in the X-Y plane is 14 ppm/°C to 20 ppm/°C.

14. The laminate according to claim 12, wherein the coefficient of thermal expansion of the laminate in the X-Y plane is 16 ppm/°C to 22 ppm/°C.

15. The laminate according to any one of the preceding claims, wherein the fluorinated perfluoro copolymer comprises a fluorinated tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer, and wherein the non-fluorinated perfluoro copolymer comprises a non-fluorinated tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer.

16. The laminate according to any one of the preceding claims, wherein the perfluorocopolymer matrix comprises 50 to 90 weight percent of the fluorinated perfluorocopolymer.

17. The laminate of claim 16, wherein the perfluorocopolymer matrix comprises 10 to 50 weight percent of the non-fluorinated perfluorocopolymer.

18. The laminate of any one of the preceding claims, wherein the number of carboxyl end groups per million carbon atoms in the perfluorocopolymer matrix is sufficient to prevent the laminate from forming conductive anodic filaments (CAFs).

19. The laminate of any one of the preceding claims, wherein the number of carboxyl end groups per million carbon atoms in the perfluorocopolymer matrix provides the laminate with a peel strength between the dielectric substrate and the conductive coating greater than 2 pounds per inch.

20. The laminate according to any one of the preceding claims, wherein the number of carboxyl end groups per million carbon atoms in the perfluorocopolymer matrix is from 30 to 70.

21. The laminate according to any one of the preceding claims, wherein the fluorinated perfluorocopolymer has 5 or fewer carboxyl end groups per million carbon atoms.

22. The laminate according to any one of the preceding claims, wherein the non-fluorinated perfluorocopolymer has from 100 to 300 carboxyl end groups per million carbon atoms.

23. The laminate according to any one of the preceding claims, wherein the perfluorocopolymer matrix has a melt flow rate (MFR) of 10 to 30 g/10 min.

24. The laminate according to any one of the preceding claims, wherein the perfluorocopolymer matrix has a solder float resistance of at least 10 seconds at 288°C.

25. The laminate according to any one of the preceding claims, wherein the L-glass has a basis weight of less than 100 g/ ^m2 .

26. The laminate of claim 25 wherein the L-glass fabric has a basis weight of less than 50 g/ ^m2 .

27. The laminate according to any one of the preceding claims, wherein the L-glass fabric has a thickness of 10 to 100 μm.

28. The laminate according to claim 27, wherein the L-glass fabric has a thickness of 10 μm to 30 μm.

29. The laminate of any one of the preceding claims wherein the L-glass fabric comprises an aminosilane or methacrylate silane surface chemistry treatment.

30. The laminate of any one of the preceding claims, wherein the L-glass fabric comprises a plasma treated or corona treated L-glass fabric.

31. A laminate according to any one of the preceding claims, wherein the L-glass fabric is impregnated with a fluoropolymer.

32. The laminate of any one of the preceding claims, wherein the L-glass fabric comprises a fluoropolymer coating.

33. The laminate of any one of the preceding claims wherein the L-glass fabric is pre-treated with a fluoropolymer treating agent prior to incorporation into the laminate.

34. The laminate of any one of the preceding claims, wherein the dielectric substrate comprises 5 to 20 volume percent of the L-glass fabric and 80 to 95 volume percent of the perfluorocopolymer matrix.

35. The laminate according to any one of the preceding claims, wherein the L-glass fabric has a water contact angle of 0° to 60°.

36. A laminate according to any one of the preceding claims, wherein the additive material comprises inorganic particles.

37. The laminate of claim 36, wherein the inorganic particles comprise particles of cerium oxide, titanium dioxide, silicon dioxide, barium titanate, calcium titanate, or zinc oxide.

38. A laminate according to any one of the preceding claims, wherein the additive material comprises a thermosetting polymer.

39. A laminate according to any one of the preceding claims, wherein the additive material is present in the perfluorocopolymer matrix at a volume percentage of less than 2%.

40. The laminate according to any one of the preceding claims, wherein the additive material is uniformly dispersed throughout the perfluorocopolymer matrix.

41. A laminate according to any one of the preceding claims, wherein the conductive coating is provided on two opposing surfaces of the dielectric substrate.

42. A laminate according to any one of the preceding claims, wherein the conductive plating comprises copper foil.

43. The laminated product of claim 42, wherein the copper foil is disposed on the surface of the dielectric substrate by a lamination process.

44. A laminate according to any preceding claim, wherein the conductive coating has a thickness of less than 72 μm.

45. The laminate according to claim 44, wherein the thickness of the conductive plating layer is 5 μm to 18 μm.

46. A laminate according to any one of the preceding claims, wherein the conductive coating has a root mean square (RMS) roughness of less than 1 μm.

47. The laminate of claim 46, wherein the conductive coating has an RMS roughness of less than 0.5 μm.

48. A printed circuit board, comprising:

The laminate according to any one of the preceding claims,

A conductor pattern is formed in the conductive plating layer.

49. The printed wiring board of claim 48, wherein a through hole is defined through the thickness of the laminate; and comprising a copper film that plates the through hole.

50. A multilayer printed circuit board, comprising:

A multi-layer laminate structure comprising a plurality of printed wiring boards according to claim 48 or 49.

51. The multilayer printed wiring board of claim 50, comprising a thermoplastic adhesive disposed between adjacent printed wiring boards in the laminate structure.

52. The multilayer printed wiring board of claim 51, wherein the thermoplastic adhesive bonds at a temperature of 0°C to 200°C below the melting point of the perfluorocopolymer matrix.

53. The multilayer printed wiring board of claim 52, wherein the thermoplastic adhesive bonds at a temperature of 0°C to 50°C below the melting point of the perfluorocopolymer matrix.

54. The multilayer printed wiring board of claim 50, comprising a thermosetting adhesive disposed between adjacent printed wiring boards in the laminated structure.

55. The multilayer printed wiring board according to claim 54, wherein the thermosetting adhesive is cured at a temperature of 150°C to 250°C.

56. A multilayer printed wiring board according to any one of claims 5048 to 55, wherein a through hole is defined through at least a portion of the thickness of the multilayer printed wiring board; and includes a copper film that plates the through hole.

57. An antenna capable of being used with a 5G communications network, the antenna comprising:

A printed wiring board according to any one of claims 50 to 56.

58. A method for manufacturing a multilayer printed wiring board, the method comprising:

forming a conductor pattern in the conductive plating layer of each of a plurality of laminates according to claim 1 to form a corresponding printed wiring board; and

A plurality of printed wiring boards are laminated to form a multi-layer laminate structure.

59. The method of claim 58, wherein laminating the plurality of printed wiring boards comprises adhering adjacent printed wiring boards using a thermoplastic adhesive.

60. The method of claim 59, comprising bonding the thermoplastic adhesive at a temperature of 0°C to 200°C below the melting point of the perfluorocopolymer matrix.

61. The method of claim 60, comprising bonding the thermoplastic adhesive at a temperature of 0°C to 50°C below the melting point of the perfluorocopolymer matrix.

62. The method of claim 58, wherein laminating the plurality of printed wiring boards comprises using a thermosetting adhesive to adhere adjacent printed wiring boards.

63. The method of claim 62, comprising curing the thermosetting adhesive at a temperature of 150°C to 250°C.

64. A method according to any one of claims 58 to 63, comprising defining a through hole through at least a portion of the thickness of the multilayer laminate structure.

65. The method of claim 64, comprising defining the through-holes in an ultraviolet laser drilling process.

66. A method of making a laminated product, the method comprising:

A layered article is formed, the layered article comprising:

A first polymer film and a second polymer film, each film comprising:

a perfluoro copolymer matrix comprising a fluorinated perfluoro copolymer and a non-fluorinated perfluoro copolymer, and

an additive material capable of absorbing ultraviolet light,

An L-glass fabric disposed between the first polymer film and the second polymer film; and

a conductive plating layer disposed in contact with the first film; and

Heat and pressure are applied to the layered article to form the laminate.

67. The method of claim 66, wherein the fluorinated perfluoro copolymer comprises a fluorinated tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer and the non-fluorinated perfluoro copolymer comprises a non-fluorinated tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer.

68. The method of claim 66 or 67, wherein applying heat and pressure to the layered article comprises compressing the layered article in a heated press plate.

69. The method of any one of claims 66 to 68, wherein applying heat and pressure to the layered article comprises processing the layered article in a roll-to-roll lamination process.

70. The method of any one of claims 66 to 69, wherein applying heat and pressure to the layered article comprises applying a temperature to the layered article that is 10°C to 30°C above the melting point of the perfluorocopolymer matrix.

71. The method of any one of claims 66 to 70, wherein applying heat and pressure to the layered article comprises applying a temperature of 300°C to 400°C to the layered article.

72. The method of any one of claims 66 to 71, wherein applying heat and pressure to the layered article comprises applying a pressure of 200 psi to 1000 psi to the layered article.

73. The method of any one of claims 66 to 72, comprising forming the first film and the second film in a melt processing and extrusion process.

74. The method of claim 73, wherein forming the first film and the second film comprises mixing the fluorinated perfluoro copolymer and the non-fluorinated perfluoro copolymer.

75. The method of claim 74, comprising dispersing an additive material in the fluorinated perfluorocopolymer prior to mixing the fluorinated perfluorocopolymer and the non-fluorinated perfluorocopolymer.

76. The method of any one of claims 66 to 75, comprising treating the L-glass fabric with a fluoropolymer treating agent.

77. The method of claim 76, wherein treating the L-glass fabric with a fluoropolymer treatment comprises coating the L-glass fabric with a fluoropolymer coating.

78. The method of claim 77, wherein coating the L-glass fabric with a fluoropolymer coating comprises coating the L-glass fabric in a solution coating process.

79. The method of claim 77 or 78, wherein coating the L-glass fabric with a fluoropolymer coating comprises depositing fluoropolymer particles on a surface of the L-glass fabric.

80. The method of any one of claims 66 to 79, wherein each polymer film comprises a first layer and a second layer, the first layer comprising the fluorinated perfluoro copolymer and the non-fluorinated perfluoro copolymer, the second layer comprising the non-fluorinated perfluoro copolymer, and wherein each second layer is disposed in contact with a quartz fabric and each second layer is disposed in contact with the conductive coating.