Laminated structures and their manufacturing methods, and circuit substrates

Abstract

This invention provides a laminate with low transmission loss and excellent properties when used as a circuit substrate. A laminate, comprising a metal layer and a fluoropolymer-containing layer adjacent to the metal layer, is characterized in that the arithmetic mean surface roughness Sa of the metal side of the bonding surface between the metal layer and the fluoropolymer-containing layer is 0.05 μm or less.

Description

Technical Field

[0001] This disclosure relates to laminates and methods for manufacturing the same, as well as circuit boards. Background Technology

[0002] In the field of circuit boards, laminates having a fluoropolymer layer and a metal layer are well known (e.g., Patent Documents 1 and 2). Such laminates are manufactured by heating and bonding a fluoropolymer film and a metal foil together.

[0003] In such laminates, surface-roughened metal foil is used as the metal foil layer to improve the adhesion between the fluoropolymer film and the metal. In recent years, research has also been conducted on using metal foils with high surface smoothness to reduce transmission losses.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2023-3106

[0007] Patent Document 2: International Publication 2016 / 104297 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The purpose of this disclosure is to provide a laminate with low transmission loss and excellent properties when used as a circuit substrate.

[0010] Methods for solving problems

[0011] This disclosure pertains to a laminate, which must have a metal layer and a fluoropolymer-containing layer adjacent to the metal layer, characterized in that the arithmetic mean surface roughness Sa of the metal side of the bonding surface between the metal layer and the fluoropolymer-containing layer is less than 0.05 μm.

[0012] Regarding the above-mentioned laminate, it is preferred that the adhesion strength between the metal layer and the fluororesin-containing layer is 0.1 N / mm or higher.

[0013] The aforementioned laminate is preferably a long strip laminate with a width of 200 mm or more.

[0014] Regarding the aforementioned laminate, it is preferable that the oxygen content at the surface of the fluoropolymer containing the layer is 1.35 atomic% or higher, as measured by a scanning X-ray photoelectron spectroscopy (XPS / ESCA) analyzer.

[0015] The preferred oxygen element ratio is 1.5 atomic% or higher.

[0016] Regarding the laminate of this disclosure, it is preferred that the difference between the oxygen ratio measured by scanning X-ray photoelectron spectroscopy (XPS / ESCA) on the surface of the fluororesin-containing layer on the side not facing the metal layer and the oxygen ratio measured by scanning X-ray photoelectron spectroscopy (XPS / ESCA) after etching the fluororesin-containing layer in the depth direction at an incident angle of 45° for 15 minutes using an argon cluster ion beam is 1.0 atomic% or more.

[0017] Regarding the above-mentioned laminate, preferably, the coefficient of kinetic friction between the surface of the metal layer and the surface of the fluororesin-containing layer is 0.70 or less.

[0018] Regarding the above-mentioned laminate, it is preferred that when the surfaces of the fluororesin-containing layers in the two laminates are bonded together at 200°C, the adhesive strength is greater than 30 N / m.

[0019] The fluororesin containing the layer is preferably a tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer or a tetrafluoroethylene / hexafluoropropylene copolymer.

[0020] The aforementioned fluororesin containing layer preferably comprises a content of unstable terminal groups relative to 1 × 10 6 It is composed of fluoropolymers with fewer than 10 carbon atoms.

[0021] Regarding the aforementioned fluororesin containing layer, it is preferred that the melt flow rate of the fluororesin at 372°C and a load of 49N is 1g / 10min to 50g / 10min.

[0022] Alternatively, the laminate of this disclosure may also have a layer (A) other than the metal layer and the fluoropolymer layer, which contains at least one selected from the group consisting of polyimide, liquid crystal polymer, polyphenylene sulfide, cyclic olefin polymer, polystyrene, epoxy resin, bismaleimide, polyphenylene oxide, polyphenylene ether, divinylbenzene and polybutadiene.

[0023] The aforementioned metal layer is preferably formed using a metal foil with a surface roughness Rz of 1.5 μm or less.

[0024] This disclosure also discloses a method for manufacturing a laminate, which is the method for manufacturing the laminate described above, characterized by a step of laminating a fluoropolymer film and a metal foil in a roller-to-roll manner at a temperature below 280°C.

[0025] Regarding the manufacturing method of the above-mentioned laminate, it is preferred that the oxygen element ratio is 1.35 atomic% or more when the surface state of at least one side of the fluoropolymer film is measured by a scanning X-ray photoelectron spectroscopy (XPS / ESCA) analyzer.

[0026] Regarding the aforementioned fluororesin film, it is preferred that the oxygen element ratio is 1.5 atomic% or more.

[0027] In the above-mentioned method for manufacturing the laminate, the fluoropolymer film is preferably such that the difference between the oxygen element ratio measured by a scanning X-ray photoelectron spectroscopy (XPS / ESCA) of one or both sides and the oxygen element ratio measured by a scanning X-ray photoelectron spectroscopy (XPS / ESCA) after etching the film in the depth direction at an incident angle of 45° for 15 minutes using an argon cluster ion beam is 1.0 atomic% or more.

[0028] This disclosure also pertains to a circuit board, characterized in that the circuit board has the aforementioned fluororesin laminate.

[0029] Invention Effects

[0030] In the laminate of this disclosure, the fluororesin contains a layer with high smoothness at the bonding surface between the layer and the metal layer, resulting in low transmission loss. Therefore, it is suitable for use as a circuit board. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating a manufacturing apparatus for the laminate of the present disclosure used in an embodiment.

[0032] Figure 2 This is a diagram illustrating an example of the laminate structure of the present disclosure. Detailed Implementation

[0033] The following provides a detailed description of this disclosure.

[0034] As mentioned above, higher surface roughness results in better adhesion between the fluoropolymer layer and the metal layer, but a smoother bonding surface is desirable to reduce transmission losses. This disclosure addresses this issue.

[0035] Methods for obtaining a laminate consisting of a fluororesin layer and a metal layer bonded together include bonding a metal foil to a fluororesin film and metal vapor deposition on the fluororesin film. In the case of bonding a metal foil to a fluororesin film, a metal foil with high smoothness is used as the metal foil, and by studying the bonding conditions, a laminate with excellent surface smoothness at the bonding surface can be obtained.

[0036] Furthermore, when a laminate is obtained by metal vapor deposition, a laminate with excellent surface smoothness of the bonding surface can be obtained by ensuring that the cooling roller and the film are fully bonded during the vapor deposition process.

[0037] In the case of laminates obtained by bonding metal foil to a fluoropolymer film, the bonding conditions become important. If the bonding conditions are inappropriate, both the surface smoothness of the bonding surface and the adhesion cannot be achieved. That is, even if a metal foil with high smoothness is used as the material, if the bonding conditions are inappropriate, either the bond strength or the surface smoothness of the bonding surface will deteriorate. In this disclosure, a metal foil with excellent smoothness was used, and the bonding conditions with the fluoropolymer film (the film containing the fluoropolymer layer in the laminate) were studied, thereby achieving the above-mentioned objective.

[0038] In the case of metal vapor deposition on a fluoropolymer film, the surface smoothness of the bonding surface is achieved by obtaining a tight seal with the cooling roller during vapor deposition, thereby achieving the above objective.

[0039] (Arithmetic mean surface roughness Sa)

[0040] The laminate of this disclosure is characterized in that the arithmetic mean surface roughness Sa of the metal side of the bonding surface between the metal layer and the fluororesin layer is 0.05 μm or less. Regarding the aforementioned Sa, refer to... Figure 2 . Figure 2 This figure illustrates an example of a laminate of the present disclosure, having a structure formed by bonding a fluoropolymer-containing layer (3-A) to a metal layer (3-B). The metal-side surface of the bonding surface (3-C) between the metal layer (3-B) and the fluoropolymer-containing layer (3-A) in such a laminate is the surface to be measured as Sa in this disclosure. The arithmetic mean surface roughness Sa is a parameter specified in ISO 25178 and is a measurement of three-dimensional surface properties. In a laminate that satisfies such a parameter, the surface smoothness of the metal layer is extremely high, and transmission loss is reduced.

[0041] More specifically, Sa is an extension of the line roughness parameter Ra (arithmetic mean height of the line) to a three-dimensional (surface) parameter. It represents the average of the absolute values ​​of the height differences (z(x,y)) of each measurement point in the reference region A relative to the average surface, and is calculated as follows.

[0042] [Formula 1]

[0043] The arithmetic mean surface roughness Sa of the metal side of the bonding surface between the metal layer and the fluororesin-containing layer was obtained by observing the bonding surface of the metal layer and the fluororesin-containing layer using a VK-X1000 laser microscope (manufactured by KEYENCE Co., Ltd.) and calculating the arithmetic mean roughness (Sa) according to ISO 25178. The two-dimensional surface area of ​​the measurement region is 60091 μm. 2Specifically, the measurement of the bonding surface between the metal layer and the fluororesin-containing layer is performed as follows: The laminate is positioned in the apparatus with the fluororesin side facing up and the metal side facing down. A laser microscope is a device that irradiates with a laser and performs surface analysis based on the reflected light; therefore, if the laser irradiation position is lowered, there are two reflection points on the laminate. The reflection from the outermost surface originates from the resin surface, and the reflection from the second layer originates from the bonding surface between the metal layer and the fluororesin-containing layer. The result of analyzing the reflection data of this second layer is taken as the arithmetic mean surface roughness Sa of the metal side of the bonding surface between the metal layer and the fluororesin-containing layer.

[0044] Laminates formed by bonding a metal layer to a fluoropolymer-containing layer are known. However, laminates that maintain high surface smoothness of the bonding surface after bonding are previously unknown. According to this disclosure, a laminate with a small reduction in transmission loss when comparing transmission loss before and after bonding can be obtained, thereby providing excellent performance as a circuit board.

[0045] More preferably, Sa is 0.10 μm or less, and even more preferably 0.05 μm or less. The lower limit of Sa is not particularly limited, for example, it can be set to 0.01 μm or more.

[0046] (Surface roughness Rz)

[0047] In the surface shape of the metal side of the bonding surface between the metal layer and the fluororesin-containing layer, the surface roughness Rz of the metal before bonding is preferably 1.5 μm or less.

[0048] Rz is a parameter in the height direction, referred to as the "maximum height". It is obtained by extracting a portion of the roughness curve measured with a laser microscope at a reference length (282 μm) and using the sum of the highest part (maximum peak height: Rp) and the deepest part (maximum valley depth: Rv).

[0049] The specific measurement method is as follows. The reflection data of the metal layer surface, which serves as the bonding surface before being bonded to the resin side, is analyzed to determine Rz.

[0050] (Adhesion strength between the metal layer and the fluororesin-containing layer)

[0051] Regarding the laminate of this disclosure, it is preferable that the adhesive strength between the metal layer and the fluororesin-containing layer is 0.1 N / mm or more. That is, it is preferable to have the smoothness of the adhesive surface as described above and sufficient adhesive strength. It should be noted that the adhesive strength in this disclosure is a value measured using the method described in the examples.

[0052] The bonding strength is more preferably 0.1 N / mm or more, more preferably 0.2 N / mm or more, and even more preferably 0.4 N / mm or more.

[0053] (Increased transmission loss rate for copper foil without roughening)

[0054] Regarding the laminate of this disclosure, it is preferred that the increase rate of transmission loss for the unroughened copper foil is 2% or less at 28 GHz. More preferably, it is 1.5% or less, and even more preferably, 1% or less. At 80 GHz, it is preferably 4% or less. More preferably, it is 3% or less, and even more preferably, 2% or less.

[0055] The increase rate of transmission loss for the unroughened copper foil mentioned above was measured by the following measurement methods (1) to (3).

[0056] (1) A printed circuit board is fabricated by forming a transmission line on one side of a laminate consisting of copper foils bonded to both sides of a fluororesin-containing layer. The transmission line constitutes a microstrip line, and a pattern with a characteristic impedance of 50Ω is selected. The transmission loss (S21: dB / cm) is measured at 28GHz and 80GHz.

[0057] (2) Next, the transmission loss (ideal value) associated with the same structure of the laminate that is in the ideal attachment state (unroughened copper foil: Sa 0.02um) is calculated (28GHz and 80GHz) using an electromagnetic field simulator.

[0058] (3) The difference between the measured value and the ideal value is divided by the ideal value as the rate of increase of transmission loss.

[0059] (Long strip membrane)

[0060] The laminated body disclosed herein is preferably a strip film. It is particularly preferred from a production cost perspective if the strip film is a continuously produced strip film. The width of the strip film is preferably 200 mm or more. Furthermore, the length is preferably 1 m or more, more preferably 3 m or more, more preferably 5 m or more, and even more preferably 10 m or more.

[0061] (Oxygen element ratio)

[0062] The preferred laminate disclosed herein is one in which the oxygen content at the surface of the fluoropolymer layer is 1.35 atomic% or more, as measured by a scanning X-ray photoelectron spectroscopy analyzer (XPS / ESCA: PHI5000VersaProbeII (manufactured by ULVAC-PHI Corporation)).

[0063] Here, the oxygen element ratio was measured using a scanning X-ray photoelectron spectroscopy (XPS / ESCA) PHI5000 VersaProbeII (manufactured by ULVAC-PHI Corporation). Carbon, oxygen, fluorine, nitrogen, and silicon were used as the detection targets, and the oxygen element ratio was determined from the composition ratios of C1s, O1s, F1s, N1s, and Si2p.

[0064] Details regarding the surface treatment methods will be described later.

[0065] Furthermore, the laminate of this disclosure is preferably such that the difference between the oxygen ratio when the surface state of the fluororesin-containing layer is measured by a scanning X-ray photoelectron spectroscopy (XPS / ESCA) device and the oxygen ratio when the fluororesin-containing layer is etched in the depth direction at an incident angle of 45° for 15 minutes using an argon cluster ion beam is 1.0 atomic% or more.

[0066] The greater the difference in oxygen ratio from the surface to the depth direction, the better the adhesion can be maintained while achieving the specified transmission loss, which is preferred in this respect.

[0067] The oxygen element ratio after the above etching is the oxygen element ratio in the surface of the fluororesin film, which is the raw material for the fluororesin containing layer, before surface treatment. Therefore, the difference in the above oxygen element ratio represents the increase in oxygen element ratio due to surface treatment.

[0068] (Coefficient of kinetic friction between the surface of the metal layer and the surface of the fluororesin-containing layer)

[0069] The aforementioned laminate is preferably characterized by a coefficient of kinetic friction of 0.70 or less between the surface of the metal layer and the surface of the fluororesin-containing layer. Particularly in the case of a strip-shaped film, a coefficient of 0.70 or less is more preferred, even more preferred is 0.50 or less, and a coefficient of kinetic friction of 0.40 or less is even more preferred.

[0070] Therefore, by setting the coefficient of dynamic friction between the metal layer surface and the fluororesin-containing layer surface to 0.70 or less, the above-mentioned problem is improved, and long strips of film can be wound up well.

[0071] The dynamic friction coefficient was measured using a Heidon Type 38 surface testing machine (manufactured by Shin-To Science Co., Ltd.). A roller-type indenter with a width of 60 mm and a diameter of 30 mm was used. The metal side of the laminate was fixed to the base as the upper surface, and the laminate with a fluororesin-containing layer on the surface was fixed to the roller for friction testing. For the balancer, a 750g weight was used, and a load of 100g was applied to the sample.

[0072] (The adhesive strength of the fluoropolymer-containing layers in the two laminates when they are bonded together at 200°C)

[0073] Two laminates of this disclosure are prepared, and the fluororesin-containing layers of each laminate are bonded together at 200°C. At this temperature, the bond strength is preferably greater than 30 N / m. The laminates of this disclosure are also frequently used in combination with other raw materials. In such cases, excellent adhesion is preferred. As such an indicator, the aforementioned bond strength is preferred, and the bond strength should be within the aforementioned range.

[0074] More specifically, regarding the aforementioned adhesive strength, the surface-treated surfaces of the fluoropolymer film, which serves as the raw material for the fluoropolymer containing layer, are overlapped. The sample, prepared by hot pressing (200°C, 0.1 MPa, 60 s), is cut into strips 10 mm wide. Using an Autograph AGS-X 100N precision universal testing machine (manufactured by Shimadzu Corporation), the unbonded portion of the strip sample is gripped by the upper and lower chucks of the Autograph while being stretched at a speed of 100 mm per minute. The peel strength is measured, and the obtained value is taken as the adhesive strength.

[0075] (Fluoropolymer contains a layer)

[0076] In the laminates disclosed herein, the resin constituting the fluoropolymer layer is not particularly limited as long as it is a fluorine-containing resin, and known fluoropolymers can be used. Preferably, it is composed of a tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer (PFA) or a tetrafluoroethylene / hexafluoropropylene copolymer (FEP).

[0077] (Per)fluoro(alkyl vinyl ether) (PAVE) can be either fluoroalkyl vinyl ether or perfluoro(alkyl vinyl ether). In this disclosure, "perfluoro(alkyl vinyl ether)" refers to an alkyl vinyl ether that does not contain a CH bond.

[0078] As a PAVE constituting the above-mentioned PAVE unit, at least one can be selected from the group consisting of monomers shown in general formula (1) and monomers shown in general formula (2), wherein, General formula (1): CF2 = CFO (CF2CFY) 1 O) p -(CF2CF2CF2O) q -R f (1) (where Y) 1 Indicates F or CF3, R f This indicates a perfluoroalkyl group with 1 to 5 carbon atoms. (p represents an integer from 0 to 5, q represents an integer from 0 to 5). General formula (2): CFX=CXOCF2OR1 (2) (In the formula, X being the same or different represents H, F, or CF3; R) 1 This refers to a straight-chain or branched fluoroalkyl group having 1 to 6 carbon atoms, which may contain 1 to 2 atoms of at least one type selected from the group consisting of H, Cl, Br and I, or a cyclic fluoroalkyl group having 5 or 6 carbon atoms, which may contain 1 to 2 atoms of at least one type selected from the group consisting of H, Cl, Br and I.

[0079] Among them, the monomer represented by general formula (1) is preferred as the PAVE, more preferably at least one selected from the group consisting of perfluoro(methyl vinyl ether), perfluoro(ethyl vinyl ether) and perfluoro(propyl vinyl ether) (PPVE), and even more preferably PPVE.

[0080] The content of PAVE units in the above-mentioned TFE / PAVE copolymer is preferably 1.0 to 10% by mass relative to all monomer units, more preferably 2.0% by mass or more, even more preferably 3.5% by mass or more, particularly preferably 4.0% by mass or more, most preferably 5.0% by mass or more, more preferably 8.0% by mass or less, even more preferably 7.0% by mass or less, particularly preferably 6.5% by mass or less, and most preferably 6.0% by mass or less. It should be noted that the amount of PAVE units is determined by... 19 The measurements were performed using F-NMR. The aforementioned TFE / PAVE copolymer may be a copolymer composed solely of TFE and PAVE units.

[0081] When the fluororesin containing layer is composed of TFE / PAVE copolymer, the melting point is preferably 280 to 322°C, more preferably 290°C or higher, and even more preferably 315°C or lower.

[0082] When the fluororesin containing layer is composed of a TFE / PAVE copolymer, the glass transition temperature (Tg) is preferably 70 to 110°C, more preferably 80°C or higher, and even more preferably 100°C or lower. The glass transition temperature is a value obtained by measuring dynamic viscoelasticity.

[0083] The above-mentioned TFE / HFP copolymer contains TFE units and HFP units. The content of TFE units in the above-mentioned TFE / HFP copolymer is preferably 70% by mass or more, more preferably 85% by mass or more, more preferably 99.8% by mass or less, more preferably 99% by mass or less, and even more preferably 98% by mass or less, relative to all monomer units.

[0084] Regarding the aforementioned TFE / HFP copolymer, it is preferred that the mass ratio of TFE units to HFP units (TFE / HFP) is 70–99 / 1–30 (mass%). More preferably, the mass ratio (TFE / HFP) is 85–95 / 5–15 (mass%).

[0085] The aforementioned TFE / HFP copolymer may further contain (per)fluoro(alkyl vinyl ether) (PAVE) units. Examples of PAVE units included in the aforementioned TFE / HFP copolymer include units identical to the aforementioned PAVE units. The aforementioned TFE / PAVE copolymer does not contain HFP units, and therefore differs from the TFE / HFP / PAVE copolymer in this respect.

[0086] When the aforementioned TFE / HFP copolymer is a copolymer comprising TFE units, HFP units, and PAVE units (hereinafter also referred to as "TFE / HFP / PAVE copolymer"), the mass ratio (TFE / HFP / PAVE) is preferably 70–99.8 / 0.1–25 / 0.1–25 (mass%). More preferably, the mass ratio (TFE / HFP / PAVE) is 75–98 / 1.0–15 / 1.0–10 (mass%). The aforementioned TFE / HFP / PAVE copolymer preferably comprises HFP units and PAVE units totaling 1% or more by mass relative to all monomer units.

[0087] The aforementioned TFE / HFP / PAVE copolymer is preferably wherein the HFP unit comprises 25% or less of all monomer units by mass. More preferably, the HFP unit content is 20% or less by mass, further preferably 18% or less by mass, and particularly preferably 15% or less by mass. Furthermore, the HFP unit content is preferably 0.1% or more by mass, more preferably 1% or more by mass, and particularly preferably 2% or more by mass. It should be noted that the HFP unit content can be determined by… 19 The measurement was performed using the F-NMR method.

[0088] The content of PAVE units is more preferably 20% by mass or less, more preferably 10% by mass or less, particularly preferably 3% by mass or less. Furthermore, the content of PAVE units is preferably 0.1% by mass or more, more preferably 1% by mass or more. It should be noted that the content of PAVE units can be determined by… 19 The measurement was performed using the F-NMR method.

[0089] The aforementioned TFE / PAVE copolymer and TFE / HFP copolymer may also contain other olefinic monomer (α) units. There are no particular limitations on the other olefinic monomer (α) units, as long as they are monomer units capable of copolymerizing with TFE, HFP, and PAVE. Examples include: fluorinated olefinic monomers such as vinylidene fluoride (VF), vinylidene fluoride (VdF), trifluoroethylene (TrFE), and chlorotrifluoroethylene (CTFE); non-fluorinated olefinic monomers such as ethylene, propylene, and alkyl vinyl ethers; and olefinic monomers with hydroxyl or carbonyl groups such as itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride. The content of other olefinic monomer (α) units is preferably 0-25% by mass, more preferably 0.1%-25% by mass.

[0090] When the above copolymer is a TFE / HFP / PAVE / other olefinic monomer (α) copolymer, the mass ratio (TFE / HFP / PAVE / other olefinic monomer (α)) is preferably 70-98 / 0.1-25 / 0.1-25 / 0.1-25 (mass%). The above TFE / HFP / PAVE / other olefinic monomer (α) copolymer preferably contains monomer units other than TFE units totaling 1% or more by mass.

[0091] The melting point of the above-mentioned TFE / HFP copolymer is preferably 200 to 322°C, more preferably above 200°C, even more preferably above 220°C, more preferably below 300°C, and even more preferably below 280°C.

[0092] The glass transition temperature (Tg) of the above-mentioned TFE / HFP copolymer is preferably 60°C to 110°C, more preferably 65°C or higher, and even more preferably 100°C or lower. The above-mentioned glass transition temperature is a value obtained by dynamic viscoelasticity measurement.

[0093] The aforementioned fluoropolymers can be manufactured, for example, by appropriately mixing monomers, polymerization initiators, and other additives that will become its constituent units and then performing emulsion polymerization, suspension polymerization, or other known methods. Among these, emulsion polymerization is more preferred.

[0094] The preferred melt flow rate of the fluororesin contained in the fluororesin layer at 372°C and 49N load is 1–50 g / 10 min.

[0095] Fluoropolymer containing layers preferably consists of unstable terminal groups in an amount relative to 1 × 10 6 It is composed of fluoropolymers with fewer than 10 carbon atoms.

[0096] The fewer functional groups in the aforementioned fluoropolymer, the better, especially the fewer unstable terminal groups. Methods for producing such fluoropolymers include: methods that adjust the manufacturing conditions (during the polymerization reaction); and methods that reduce the number of unstable terminal groups by subjecting the polymerized fluoropolymer to fluorine gas treatment, heat treatment, supercritical gas extraction treatment, etc. Fluorine gas treatment is preferred from the perspective of excellent processing efficiency and the conversion of some or all of the unstable terminal groups into -CF3, thus becoming stable terminal groups. Using a fluoropolymer with a reduced number of unstable terminal groups in this way is preferable from the perspective of reduced electrostatic tangent and reduced electrical signal loss.

[0097] The number of unstable terminal groups mentioned above is not particularly limited, but relative to every 10 of the fluoropolymer... 6 The number of carbon atoms in the main chain is preferably 450 or less, more preferably 250 or less, even more preferably 100 or less, and most preferably 50 or less. Considering the effect of reducing the dielectric loss tangent, it is preferably less than 10, and even more preferably 5 or less.

[0098] As unstable terminal groups, specific examples include functional groups such as -COF, -COOH free, -COOHbonded, hydroxyl (-CH2OH, etc.), -CONH2, -COOR (R=CH3, etc.), -CF2H, and -OCOO-R (propyl carbonate, etc.).

[0099] The number of unstable terminal groups was specifically measured using the following method. First, the aforementioned fluororesin was melted and compressed to form a film with a thickness of 0.25–0.3 mm. The film was analyzed using Fourier transform infrared spectroscopy to obtain the infrared absorption spectrum of the fluororesin, and a differential spectrum was obtained between this spectrum and the background spectrum of a fully fluorinated resin without functional groups. Based on the absorption peaks of specific functional groups appearing in this differential spectrum, the number of unstable terminal groups relative to the number of terminal groups in the fluororesin per 1 × 10⁻⁶ cells was calculated according to the following formula (A). 6 The number of unstable terminal groups on each carbon atom.

[0100] N = I × K / t (A)

[0101] I: Absorbance

[0102] K: Correction coefficient

[0103] t: Membrane thickness (mm)

[0104] For reference, the absorption frequencies, molar absorptivity, and correction factors for the unstable terminal groups in this specification are shown in Table 1. Additionally, the molar absorptivity was determined from FT-IR measurements of the low-molecular-weight model compounds.

[0105] [Table 1]

[0106] The fluoropolymer layer in the laminate disclosed herein may also contain components other than fluoropolymers. There are no particular limitations on the components that may be included, and examples include fillers such as silica particles, short glass fibers, and fluorine-free thermosetting / thermoplastic resins. The content of components other than fluoropolymers is not particularly limited, but is more preferably 10% by mass or less, and even more preferably 5% by mass or less.

[0107] In the laminates disclosed herein, the thickness of the fluoropolymer layer is preferably 1 to 100 μm. The upper limit is more preferably 50 μm or less, and even more preferably 30 μm or less. The lower limit is more preferably 3 μm or more, and even more preferably 5 μm or more.

[0108] In addition, the thickness of the fluoropolymer-containing layer was measured by reflection spectrophotometry using the F20 film thickness measurement system (manufactured by Filmetrics).

[0109] (Metal layer)

[0110] In this disclosure, examples of metals constituting the metal foil layer include copper, aluminum, SUS, nickel, and gold. Alloys of these metals can also be used. From the viewpoint of conductivity and circuit fabrication, copper is preferred. A heat-resistant layer (nickel plating, titanium plating, etc.) and a rust-proof layer (chromate treatment layer, etc.) can also be formed on the surface of the copper foil. Furthermore, the surface can be chemically treated with a silane coupling agent. Among these, copper foil is preferred.

[0111] The thickness of the aforementioned metal foil layer is preferably 1 to 100 μm.

[0112] The aforementioned metal layer can be a metal foil layer, or a metal layer or metal foil vacuum-deposited on a fluororesin-containing layer.

[0113] (Layered structure of a laminate)

[0114] The laminate disclosed herein can be a two-layer structure consisting of the aforementioned fluororesin-containing layer and metal layer, or a three-layer or more structure having any one or both of the above-mentioned two layers. Furthermore, it can also be a three-layer or more structure having a layer (A) other than the metal layer and the fluororesin-containing layer.

[0115] Examples of layers (A) other than the metal layer and the fluoropolymer layer include polyimide, liquid crystal polymer, polyphenylene sulfide, cyclic olefin polymer, and polystyrene. Examples of thermosetting resins include epoxy resin, bismaleimide, polyphenylene oxide, polyphenylene ether, divinylbenzene, and polybutadiene.

[0116] When the laminate of this disclosure has the above-described layer (A), the layer structure can be configured as a metal / fluororesin containing layer / layer (A). A laminate with a fluororesin containing layer / metal on one or both sides of layer (A) is also possible.

[0117] (Manufacturing method)

[0118] The method for manufacturing the laminate of this disclosure is described in detail below.

[0119] In order to obtain the laminate of this disclosure, the metal foil used as material needs to be adjusted to a metal foil with high smoothness, and the conditions in the process of bonding with the fluoropolymer film need to be further adjusted.

[0120] Regarding the metal foil used as a raw material for manufacturing the laminate of this disclosure, the arithmetic mean surface roughness Sa is preferably 0.3 μm or less, more preferably 0.15 μm or less, and even more preferably 0.04 μm or less. Using a metal foil with high surface smoothness before bonding is important for achieving the objectives of this invention.

[0121] For metal foils with an arithmetic mean surface roughness Sa of 0.04 μm or less, commercially available products can be used, such as electrolytic copper foil CF-T9DA-SV-18 (thickness 18 μm, Rz 0.85 μm, Sa 0.02 μm (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.)).

[0122] The fluoropolymer membrane used as a raw material for manufacturing the laminate of this disclosure is not particularly limited, and any known conventional membrane made of the fluoropolymer as described above can be used.

[0123] When bonding the aforementioned metal foil to the fluororesin film, heating is required. However, when manufacturing the laminate disclosed herein, it is preferable to set the heating temperature to below -20°C, which is the melting point of the fluororesin. For example, when the fluororesin is PFA, it is preferable to set it to below 280°C, more preferably to 120–280°C. More preferably, it is 200–280°C, and even more preferably, it is 220–280°C. The heat treatment process can be performed by lamination using a roller-to-roll method, or by heat-treating the fluororesin coated on the metal foil.

[0124] In other words, by heating at a low temperature below the melting point of -20°C, the smoothness of the bonding surface is less likely to be compromised during the bonding process of the metal foil layer and the fluororesin-containing layer, which is preferable from this perspective. Although the mechanism is not yet clear, it is speculated as follows: Since resin has the property of expanding when heated and melting and shrinking when cooled and solidifying, when bonding with metal foil at a temperature above the melting point of -20°C, the metal foil is deformed by the shrinkage of the resin. Therefore, if the bonding is performed at a melting point below -20°C, the deformation of the metal foil caused by this shrinkage can be suppressed, and the smoothness of the bonding surface is less likely to be compromised.

[0125] It should be noted that, in this disclosure, the melting point of fluoropolymers is measured using a differential scanning calorimeter according to ASTM D-4591 at a heating rate of 10 °C / min, and the temperature corresponding to the peak of the obtained endothermic curve is taken as the melting point.

[0126] In the manufacture of the laminate disclosed herein, there is no particular limitation on the method of bonding the metal foil to the fluoropolymer film. From the viewpoint of maximizing manufacturing efficiency, a method of laminating by roller to roller is particularly preferred.

[0127] By using a roller-to-roll manufacturing method, low costs can be achieved, and it is also preferred in terms of obtaining long, thin laminates. When manufacturing laminates using this method, the width of the laminate is not particularly limited, but it is preferably 200 mm or more.

[0128] The aforementioned fluoropolymer film preferably improves its adhesion by performing surface modification on one or both sides, thereby enabling bonding at temperatures below the melting point of the fluoropolymer, such as 120°C to 280°C.

[0129] By laminating a metal foil onto a fluoropolymer film obtained using such a method under appropriate conditions, the laminate of this disclosure can be suitably obtained.

[0130] The specific methods for surface modification described above are not particularly limited; specific examples are detailed below. Surface modification of fluoropolymer films can be performed using conventional discharge treatments such as corona discharge, glow discharge, plasma discharge, and sputtering. For example, in addition to controlling the surface free energy by introducing oxygen, nitrogen, hydrogen, carbon dioxide, methane, ethylene, etc., into the discharge atmosphere, it is also possible to: expose the surface to be modified to an inert gas containing organic compounds, i.e., an atmosphere of inert gas containing organic compounds, and apply a high-frequency voltage between the electrodes to generate a discharge, thereby generating active species on the surface; then, introduce functional groups of organic compounds or perform graft polymerization on polymerizable organic compounds, thereby performing surface modification. Examples of such inert gases include nitrogen, helium, and argon.

[0131] Organic compounds in the aforementioned inert gases containing organic compounds can include polymeric or non-polymeric organic compounds containing oxygen atoms, such as vinyl esters like vinyl acetate and vinyl formate; acrylates like glycidyl methacrylate; ethers like vinyl ethyl ether, vinyl methyl ether, and glycidyl methyl ether; carboxylic acids like acetic acid and formic acid; alcohols like methanol, ethanol, phenol, and ethylene glycol; ketones like acetone and methyl ethyl ketone; carboxylic acid esters like ethyl acetate and ethyl formate; and acrylic acids like acrylic acid and methacrylic acid. From the viewpoint of the modified surface being less prone to deactivation, i.e., having a long lifespan, vinyl esters, acrylates, and ketones are preferred, with vinyl acetate and glycidyl methacrylate being particularly preferred.

[0132] The concentration of the organic compound in the aforementioned inert gas containing organic compounds varies depending on its type and the type of fluororesin being surface-modified, and is typically 0.1–3.0% by capacity, preferably 0.1–1.0% by capacity, more preferably 0.15–1.0% by capacity, and even more preferably 0.30–1.0% by capacity. The discharge conditions can be appropriately selected based on the degree of surface modification targeted, the type of fluororesin, and the type or concentration of the organic compound. Typically, a discharge rate of 50–1500 W·min / m is used. 2 Optimal 70W·min / m 2 Above and 1400 W·min / m 2 The discharge treatment is performed within the following range. The treatment temperature can be any temperature within the range of 0°C to 100°C. To avoid film elongation and wrinkling, a temperature of 80°C or lower is preferred. Regarding the degree of surface modification of the fluoropolymer film, considering that the oxygen element on the surface may be deactivated by heat applied during lamination with the metal foil, thereby reducing adhesion, the oxygen element content observed using ESCA is 1.5% or more, preferably 1.75% or more, more preferably 2.0% or more, and even more preferably 2.5% or more. There is no specific upper limit, but considering the impact on productivity or other physical properties, 25.0% or less is preferred. The nitrogen element content is not specifically defined, but is preferably 0.1% or more. Furthermore, the thickness of one fluoropolymer film is preferably 1.0 to 1000 μm, more preferably 12.5 to 100 μm, and even more preferably 5 to 30 μm.

[0133] In the above method, it is preferable to perform a surface treatment such that the oxygen element ratio when the surface states of both sides of the fluoropolymer film are measured by a scanning X-ray photoelectron spectroscopy (XPS / ESCA) device is 1.5 atomic% or more. More preferably, the oxygen element ratio is 1.75 atomic% or more.

[0134] In the above method, if a gas containing organic compounds is used for surface treatment, the local unevenness of the resin surface can be imparted, resulting in a dynamic friction coefficient of less than 0.4 between the surface of the metal foil layer and the surface of the fluororesin-containing layer. This is preferable from this perspective. That is, not only is the adhesive strength good, but the dynamic friction coefficient is also low. Therefore, when producing long strip laminates, it is preferable to avoid winding defects.

[0135] For fluoropolymer films that have undergone plasma treatment using the above method, annealing can also be performed to remove residual stress in advance. This reduces dimensional changes in the fluoropolymer film caused by heat from the pressure rollers during the lamination process with metal foil, allowing for wrinkle-free bonding and suppressing defects in the laminate's appearance. These heat treatments reduce the surface oxygen content of the fluoropolymer film; therefore, surface modification is preferably performed under conditions where sufficient surface oxygen is obtained at the moment the fluoropolymer film is bonded to the metal foil.

[0136] Annealing can be performed by heat treatment. This heat treatment can be carried out, for example, by passing the material through a heating furnace in a roller-to-roll manner. Alternatively, it can be performed in an intermittent drying oven.

[0137] The annealing temperature is preferably above the glass transition temperature of the fluoropolymer and below its melting point, more preferably above the glass transition temperature and below the melting point of the fluoropolymer, and even more preferably above the glass transition temperature and below the melting point of the fluoropolymer. The annealing time is not particularly limited; for example, it can be adjusted appropriately within the range of 0.5 minutes to 60 minutes.

[0138] When heating is performed using the roller-to-roll method described above, the tension can be adjusted appropriately based on the film thickness and set temperature, and is preferably below 20 N / m. Heating under such conditions can effectively alleviate internal stress and prevent dimensional changes, making it preferable from this perspective.

[0139] There is no particular limitation on the order of the above surface treatment and annealing treatment, and the number of times each process is performed is not limited to once, but can be performed more than twice.

[0140] Regarding the laminate disclosed herein, since the surface roughness of the bonding surface between the metal layer and the fluororesin-containing layer is relatively small, it has the advantage of low transmission loss. Therefore, it is suitable for use in circuit boards and the like. In particular, it is especially suitable for use in circuit boards for high-frequency circuits.

[0141] In this disclosure, the high-frequency circuit is not only composed of circuits that transmit only high-frequency signals, but also includes circuits that simultaneously provide, on the same plane, a transmission path for converting high-frequency signals into low-frequency signals and outputting the generated low-frequency signals to the outside, a transmission path for supplying power for driving high-frequency corresponding components, and other transmission paths for transmitting non-high-frequency signals. Furthermore, it can also be used as a circuit board for antennas, filters, etc.

[0142] Example

[0143] The present disclosure is described in detail below based on embodiments. In the following embodiments, unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass," respectively.

[0144] [Membrane manufacturing methods]

[0145] (Method for manufacturing long strip film 1)

[0146] In an extruder, a nickel filter, made by overlapping multiple #300 or higher meshes and ultrasonically cleaning, is inserted between the screw and the die. In this 360°C extruder, a TFE / PPVE copolymer with terminal fluorination is used as the fluoropolymer (composition: TFE / PPVE = 96.1 / 3.9 (mass%), MFR: 16.0 g / 10 min, melting point: 305°C, number of unstable terminal groups: undetectable (relative to 10...). 6 The main chain carbon atoms are less than 1) (hereinafter: F-type PFA), extruded from a 1700mm wide T-die, pulled by a metal cooling roller, and then wound onto a winding core to form a long strip film 1 with a width of 1300mm and a thickness of 12.5μm.

[0147] (Manufacturing method of long strip film 2)

[0148] The same process will be used, and an un-terminated TFE / PPVE copolymer (composition: TFE / PPVE = 95.4 / 4.6 (wt%), MFR: 15.8 g / 10 min, melting point: 305 °C, number of unstable terminal groups: relative to 10) will be used. 6 A membrane made of fluoropolymer (PFA) with 297 carbon atoms in the main chain (hereinafter: PFA) is used as a long roll film 2.

[0149] (Manufacturing method of strip films 3 and 4)

[0150] Next, the two sides of the obtained long strip film 1 were surface treated (while nitrogen gas containing 0.50% by capacity vinyl acetate was passed through the discharge electrode and the roller grounding electrode of the plasma discharge device, the film was continuously passed along the roller grounding electrode at a speed of 265 W·min / m). 2The plasma discharge quantity is applied to both sides of the membrane to perform plasma discharge treatment, and the surface-treated strip membrane 3 is wound into a roll. The membrane is then cut into 500mm wide pieces, and the resulting membrane is used as strip membrane 4.

[0151] (Manufacturing method of long strip films 5 and 6)

[0152] Next, the two sides of the obtained long roll film 2 were surface treated (while nitrogen gas containing 0.50% by capacity vinyl acetate was passed through the vicinity of the discharge electrode and the roller grounding electrode of the plasma discharge device, the film was continuously passed along the roller grounding electrode at a speed of 265 W·min / m). 2 The plasma discharge quantity is applied to both sides of the membrane to perform plasma discharge treatment, and the surface-treated strip membrane 5 is wound into a roll. The membrane is then cut into 500mm wide pieces, and the resulting membrane is used as the strip membrane 6.

[0153] (Manufacturing method of long strip film 7)

[0154] The long strip film 4 is passed through an annealing furnace at 180°C (in air atmosphere) in a roller-to-roll manner, and the film is cooled in the cooling zone, and the long strip film is wound into a roll. The film is then cut into 500mm wide strips, and the resulting film is used as the long strip film 7.

[0155] (Manufacturing method of long strip film 8)

[0156] The two sides of the obtained long strip film 1 are surface treated (while He gas containing 0.5% by volume CO2 and 0.5% by volume O2 is passed through near the discharge electrode and the roller grounding electrode of the plasma discharge device, the film is continuously passed along the roller grounding electrode at a speed of 1200 W·min / m). 2 The discharge amount is used to perform plasma discharge treatment on both sides of the membrane, and the surface-treated strip membrane is wound into a roll. The membrane is cut into 500mm wide pieces, and the resulting membrane is used as strip membrane 8.

[0157] [Adhesion to copper foil]

[0158] (Example 1)

[0159] use Figure 1 The heat lamination apparatus shown laminates a long strip of film 4 with a long strip of copper foil 2 (electrolytic copper foil CF-T9DA-SV-18 (thickness 18μm / Rz 0.85μm, Sa 0.020μm) manufactured by Fukuda Metal Foil Powder Co., Ltd.) with a width of 520mm to obtain a laminate 21. During lamination, the surface temperature (pressing temperature) of a pair of lamination rollers 100 (metal rollers) is 280°C, the pressure applied by the lamination rollers is 20kN / m, and the conveying speed of the film and copper foil is 3m / min.

[0160] (Examples 2-9)

[0161] As shown in Table 2, the pressing temperature was changed, and otherwise, laminates 22 to 29 were obtained in the same manner as laminate 21 described above.

[0162] (Example 10)

[0163] Using a long strip film 7 instead of a long strip film 2, and setting the pressing temperature to 280°C, a laminate 30 is obtained in the same manner as the laminate 21 described above.

[0164] (Example 11)

[0165] Using a long strip film 6 instead of a long strip film 2, and setting the pressing temperature to 280°C, a laminate 31 is obtained in the same manner as the laminate 21 described above.

[0166] (Example 12)

[0167] Using a long strip film 8 instead of a long strip film 2, and setting the pressing temperature to 260°C, a laminate 32 is obtained in the same manner as the laminate 21 described above.

[0168] (Refer to Examples 1-3)

[0169] Except for changing the pressing temperature as described in Table 3, laminates 33 to 35 are obtained in the same manner as laminate 21 described above.

[0170] (See Example 4 for reference)

[0171] Using a long strip film 7, the pressing temperature is set to 300°C, and otherwise, a laminate 36 is obtained in the same manner as the laminate 21 described above.

[0172] (Comparative Examples 1-3)

[0173] Except for changing the pressing temperature as described in Table 3, laminates 37 to 3940 are obtained in the same manner as the laminate 32 described above.

[0174] (Methods for measuring and evaluating the oxygen ratio)

[0175] The oxygen ratio on the surface of the surface-treated resin was measured using a scanning X-ray photoelectron spectroscopy (XPS / ESCA) PHI5000 VersaProbeII (manufactured by ULVAC-PHI Corporation) under monochromatic Al Kα X-ray source conditions and an incident angle of 45°. Carbon, oxygen, fluorine, nitrogen, and silicon were used as the detection targets. The oxygen ratio was determined from the composition ratio of C1s, O1s, F1s, N1s, and Si2p.

[0176] (Sa on the copper foil side of the bonding surface between the laminated metal foil and the fluororesin-containing layer)

[0177] The bonding surface between the metal layer and the fluororesin-containing layer was observed using a VK-X1000 laser microscope (manufactured by KEYENCE Co., Ltd.), and the arithmetic mean roughness (Sa) was calculated according to ISO 25178. The two-dimensional surface area of ​​the measurement region was 60091 μm. 2 Specifically, the measurement of the bonding surface between the metal layer and the fluororesin is performed as follows: The laminate is positioned in the apparatus with the fluororesin side facing upwards and the metal side facing downwards. A laser microscope is a device that irradiates with a laser and performs surface analysis based on the reflected light. If the laser irradiation position is lowered, there are two reflection points on the laminate. The reflection from the outermost surface originates from the resin surface, and the reflection from the second layer originates from the bonding surface between the metal layer and the fluororesin-containing layer. The result obtained by analyzing the reflection data of this second layer is taken as the arithmetic mean surface roughness Sa of the metal side of the bonding surface between the metal layer and the fluororesin-containing layer.

[0178] Measurement conditions are as follows: for filter type, apply Gaussian filter, S filter with a diameter of 2.5 μm, and L filter with a diameter of 0.08 mm.

[0179] In addition, the correction for the analysis of Sa is performed as follows.

[0180] Surface shape correction: Remove quadratic curves and ripples (intensity: 5)

[0181] Smoothing: Median, Size 3×3

[0182] (Increase in transmission loss for unroughened copper foil)

[0183] First, a printed circuit board was fabricated by forming transmission lines on one copper foil surface of a laminate consisting of two sides of a fluororesin-containing layer (50 μm thick). High-frequency transmission characteristics were evaluated using a vector network analyzer (Keysight Technologies N5290A). The transmission lines were constructed as microstrip lines, and a pattern with a characteristic impedance of 50 Ω was selected. The transmission loss (S21: dB / cm) at 28 GHz and 80 GHz was measured (measured value). Next, the transmission loss (ideal value) of the laminate with the same structure under ideal attachment conditions (unroughened copper foil: Sa 0.02 μm) was calculated using an electromagnetic field simulator (Ansys). In each embodiment and comparative example, the difference between the measured value and the ideal value was calculated as the rate of increase in transmission loss.

[0184] (Adhesion strength between copper foil and fluororesin-containing layer)

[0185] Prepreg R-5680(J) (132μm thick) (manufactured by Panasonic Corporation) was prepared. The laminate 21 prepared in Example 1 was cut into two 200mm square laminates. The laminates were overlapped on both sides of the prepreg with the fluororesin side facing the prepreg, thus obtaining a copper foil layer / fluororesin-containing layer / prepreg / fluororesin-containing layer / copper foil layer laminate. Then, the pressing conditions were set as follows: temperature 200°C, time 75 minutes, and pressure 3.0MPa to prepare a sample for measurement, which was then cut into 10mm widths.

[0186] Adhesive tape was applied to one side of the cut sample and attached to an aluminum plate. Then, using an Autograph AGS-X 100N precision universal testing machine (manufactured by Shimadzu Corporation), a 10mm wide copper foil was gripped and stretched at a speed of 50mm per minute in a direction at 90° relative to the plane of the laminate. The peel strength between the copper foil and the fluororesin-containing layer was measured, and the obtained value was taken as the adhesive strength.

[0187] (The coefficient of kinetic friction between the copper foil surface and the fluororesin layer)

[0188] The surface properties were measured using a Heidon Type 38 surface testing machine (manufactured by Shin-To Science Co., Ltd.). A roller-type indenter with a width of 60 mm and a diameter of 30 mm was used. The metal side of the laminate was fixed to the base as the upper surface, and the laminate was fixed to the roller with the fluoropolymer layer on the surface for friction testing. A 750 g weight was used as the balancer, and a load of 100 g was applied to the sample. The average value obtained by dividing the test force obtained from the force sensor of the testing machine within a stable range by the load over 500 ms was taken as the coefficient of kinetic friction.

[0189] (The appearance of the curled-up posture)

[0190] When the roll of a 500mm wide laminate is in the form of a roll, the quality of its appearance is judged by visual inspection as follows.

[0191] ○: No wrinkles

[0192] △: There are 1 to 2 folds inside the scroll.

[0193] ×: There are more than 3 folds inside the scroll.

[0194] [Table 2]

[0195] [Table 3]

[0196] The results in Tables 2 and 3 clearly show that the transmission loss of the laminate of this disclosure is low. Furthermore, it is evident that, in the case of the laminates of Examples 1-12, friction is low, and problems caused by poor winding do not occur.

[0197] Industrial availability

[0198] The laminate disclosed herein can be appropriately used as a circuit substrate.

[0199] Label Explanation

[0200] 1: Fluorine membrane; 2: Metal foil; 21: Layered body; 100, 101: Pressure rollers; 102: Fluorine film supply roller; 103: Metal foil supply roller; 104a~c: Conveyor rollers; 105: Layered body winding roller; 3-A: Fluoropolymer contains a layer; 3-B: Metal foil layer; 3-C: The bonding surface of the fluororesin containing the layer / metal foil layer.

Claims

1. A laminate, comprising a metal layer and a fluoropolymer-containing layer adjacent to the metal layer, characterized in that, The arithmetic mean surface roughness Sa of the metal side of the bonding surface between the metal layer and the fluororesin-containing layer is less than 0.05 μm.

2. The laminated body according to claim 1, wherein, The bonding strength between the metal layer and the fluororesin-containing layer is above 0.1 N / mm.

3. The laminate according to claim 1 or 2, wherein, A laminate is a long strip laminate with a width of 200mm or more.

4. The laminate according to any one of claims 1 to 3, wherein, The oxygen content of the fluoropolymer containing the surface layer was measured to be above 1.35 atomic% using a scanning X-ray photoelectron spectroscopy (XPS / ESCA) analyzer.

5. The laminated body according to claim 4, wherein, The oxygen element ratio mentioned above is 1.5 atomic percent or more.

6. The laminate according to any one of claims 1 to 5, wherein, The difference between the oxygen ratio measured on the surface of the fluoropolymer layer using a scanning X-ray photoelectron spectroscopy (XPS / ESCA) device and the oxygen ratio measured using the same device after etching the fluoropolymer layer in the depth direction at a 45° incident angle for 15 minutes with an argon cluster ion beam is greater than 1.0 atomic%.

7. The laminate according to any one of claims 1 to 6, wherein, The coefficient of dynamic friction between the surface of the metal layer and the surface of the fluororesin-containing layer is below 0.

70.

8. The laminate according to any one of claims 1 to 7, wherein, When the surfaces of the fluoropolymer-containing layers in the two laminates are bonded together at 200°C, the bonding strength is greater than 30 N / m.

9. The laminate according to any one of claims 1 to 8, wherein, Fluoropolymers contain a layer that is a tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer or a tetrafluoroethylene / hexafluoropropylene copolymer.

10. The laminate according to any one of claims 1 to 9, wherein, Fluoropolymers contain layers with an amount of unstable end groups relative to 1×10 6 It is composed of fluoropolymers with fewer than 10 carbon atoms.

11. The laminate according to any one of claims 1 to 11, wherein, Regarding the fluororesin containing a layer, the melt flow rate of the fluororesin at 372°C and a load of 49N is 1 g / 10 min to 50 g / 10 min.

12. The laminate according to any one of claims 1 to 11, wherein, The fluororesin-containing layer uses a film with surface treatment on both sides by using nitrogen gas containing vinyl acetate and plasma discharge treatment. The metal layer uses copper foil with a surface roughness Rz of less than 1.5 μm. The laminate is obtained by laminating the fluororesin containing layer and the metal layer.

13. The laminate according to any one of claims 1 to 12, wherein, The laminate also has a layer (A) other than the metal layer and the fluoropolymer film layer. The layer (A) contains at least one selected from the group consisting of polyimide, liquid crystal polymer, polyphenylene sulfide, cyclic olefin polymer, polystyrene, epoxy resin, bismaleimide, polyphenylene oxide, polyphenylene ether, divinylbenzene and polybutadiene.

14. The laminate according to any one of claims 1 to 13, wherein, The metal layer is formed using a metal foil with a surface roughness Rz of less than 1.5 μm.

15. A method for manufacturing a laminate, which is the method for manufacturing a laminate according to any one of claims 1 to 14, characterized in that, The manufacturing method of the laminate includes the following steps: heating the fluororesin film and the metal foil in a roller-to-roll manner at a temperature below the melting point of the fluororesin of -20°C.

16. A method for manufacturing a laminate, which is the method for manufacturing a laminate according to any one of claims 1 to 14, characterized in that, The manufacturing method of the laminate includes the following steps: heat treatment of the fluoropolymer film and the metal foil in a roller-to-roll manner at a temperature below 280°C.

17. The method for manufacturing a laminate according to claim 15 or 16, wherein, The oxygen content of the fluoropolymer film measured using a scanning X-ray photoelectron spectroscopy (XPS / ESCA) device was greater than 1.5 atomic%.

18. The method for manufacturing a laminate according to any one of claims 15 to 17, wherein, Regarding fluoropolymer films, the difference between the oxygen ratio measured by scanning X-ray photoelectron spectroscopy (XPS / ESCA) on one or both sides of the surface and the oxygen ratio measured by scanning X-ray photoelectron spectroscopy (XPS / ESCA) after etching the film in the depth direction at a 45° incident angle for 15 minutes using an argon cluster ion beam is greater than 1.0 atomic%.

19. A circuit board, characterized in that, The circuit substrate has a laminate as described in any one of claims 1 to 14.

Images