Laminate

Abstract

To provide a laminate comprising a metal layer and a dielectric layer, having high delamination strength between layers and a low dielectric loss tangent of the dielectric layer. [Solution] A laminate comprising a metal layer and a dielectric layer is provided, wherein the dielectric layer contains polytetrafluoroethylene having functional groups, the peel strength between the metal layer and the dielectric layer is 1.0 N / cm or more, and the dielectric loss tangent of the dielectric layer is 0.0010 or less.

Description

[Technical Field]

[0001] This disclosure relates to laminates. [Background technology]

[0002] Patent Document 1 describes a printed circuit board material containing a crosslinkable polytetrafluoroethylene having at least one reactive functional group selected from the group consisting of a cyano group (-CN), a first functional group represented by a specific general formula, and a second functional group represented by a specific general formula, or a crosslinked polytetrafluoroethylene obtained by crosslinking crosslinkable polytetrafluoroethylene. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2009-44018 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] This disclosure aims to provide a laminate comprising a metal layer and a dielectric layer, having high delamination strength between layers and a low dielectric loss tangent of the dielectric layer. [Means for solving the problem]

[0005] The present disclosure provides a laminate comprising a metal layer and a dielectric layer, wherein the dielectric layer contains polytetrafluoroethylene having functional groups, the peel strength between the metal layer and the dielectric layer is 1.0 N / cm or more, and the dielectric loss tangent of the dielectric layer is 0.0010 or less. [Effects of the Invention]

[0006] According to this disclosure, it is possible to provide a laminate comprising a metal layer and a dielectric layer, having high delamination strength between layers and a low dielectric loss tangent of the dielectric layer. [Modes for carrying out the invention]

[0007] The following describes specific embodiments of this disclosure in detail, but this disclosure is not limited to the embodiments described below.

[0008] The laminate of this disclosure comprises a metal layer and a dielectric layer.

[0009] 1. Metal layer The laminate of this disclosure comprises a metal layer. Examples of metals forming the metal layer include copper, stainless steel, aluminum, iron, and alloys thereof, with at least one selected from the group consisting of copper and aluminum being preferred, and copper being more preferred. In one embodiment, the metal layer is formed of copper foil. Examples of copper foil include rolled copper foil and electrolytic copper foil.

[0010] The thickness of the metal layer is preferably 5 to 200 μm, more preferably 7 μm or more, even more preferably 9 μm or more, more preferably 200 μm or less, even more preferably 50 μm or less, and particularly preferably 35 μm or less.

[0011] The surface roughness (Rzjis) of the metal layer is preferably 4.0 μm or less, more preferably 3.0 μm or less, and even more preferably 2.0 μm or less. The lower limit is not particularly limited, but may be 0.01 μm or more, or 0.05 μm or more. By having the surface roughness Rzjis of the metal layer within the above range, the transmission loss of high-frequency signals that mainly flow near the surface of the metal layer can be reduced. Therefore, when a laminate having a metal layer with a surface roughness Rzjis within the above range is used as a printed circuit board, electrical signals can be transmitted at a high transmission speed. If the surface roughness Rzjis is too large, the transmission loss increases due to the skin effect. In one embodiment, the surface of the metal layer is not roughened.

[0012] Surface roughness (Rzjis) can be measured in accordance with JIS B0601-2001.

[0013] The surface of the metal layer may be chemically treated. A silane coupling treatment is preferred as the chemical treatment. A silane coupling agent having a reactive functional group can be used for the silane coupling treatment. At least one of amino groups, alkoxy groups, (meth)acrylic groups, mercapto groups, and epoxy groups is preferred as the reactive functional group.

[0014] 2. Dielectric layer The laminate of this disclosure comprises a dielectric layer, and the metal layer and the dielectric layer are directly bonded together.

[0015] The dielectric loss tangent of the dielectric layer is 0.0010 or less, preferably 0.0009 or less, more preferably 0.0008 or less, and the lower limit is not particularly limited, but may be 0.0005 or more. The dielectric loss tangent of the dielectric layer is the dielectric loss tangent of the dielectric layer alone. The dielectric loss tangent of the dielectric layer can be measured by removing the metal layer constituting the laminate, recovering only the dielectric layer, and measuring the recovered dielectric layer by the split cylinder method at 10 GHz and 25 ± 3°C.

[0016] The dielectric loss tangent of the dielectric layer can be adjusted within the above range by adjusting the type of polytetrafluoroethylene used to form the dielectric layer, the heating temperature, heating rate, and number of heating cycles for the dielectric layer.

[0017] Since the laminate of this disclosure has a dielectric layer with a low dielectric loss tangent, when the laminate of this disclosure is used as a printed wiring board, the transmission loss of high-frequency signals in the dielectric layer can be reduced.

[0018] Furthermore, the line width of the wiring pattern can be increased while suppressing the increase in transmission loss of high-frequency signals in the dielectric layer. Therefore, the transmission loss of high-frequency signals in the metal layer can also be reduced.

[0019] Furthermore, as mentioned above, if the surface roughness Rzjis of the metal layer is within the above range, the transmission loss of high-frequency signals in the metal layer can be further reduced.

[0020] The relative permittivity of the dielectric layer is preferably 2.1 to 2.6. The relative permittivity of the dielectric layer is the relative permittivity of the dielectric layer alone. The relative permittivity of the dielectric layer can be measured by removing the metal layer constituting the laminate, recovering only the dielectric layer, and measuring the recovered dielectric layer by the split cylinder method at 10 GHz and 25 ± 3°C.

[0021] In the laminate of this disclosure, the peel strength between the metal layer and the dielectric layer is 1.0 N / cm or more. Preferably, the peel strength between the metal layer and the dielectric layer is 3.0 N / cm or more, more preferably 7.0 N / cm or more, and even more preferably 10.0 N / cm or more. The upper limit is not particularly limited, but may be 20.0 N / cm or less.

[0022] The peel strength between the metal layer and the dielectric layer can be measured in accordance with JIS C 6481-1996.

[0023] By ensuring that the peel strength between the metal layer and the dielectric layer is within the above range, excellent transmission performance is maintained over a long period, and high reliability is ensured. If the peel strength between the metal layer and the dielectric layer is too low, problems such as the metal layer peeling off during use may occur when the laminate of this disclosure is used as a printed circuit board, and the excellent transmission performance will be impaired.

[0024] The dielectric layer included in the laminate of the present disclosure contains polytetrafluoroethylene having a functional group. Conventionally, it has been difficult to bond a dielectric layer formed of polytetrafluoroethylene to a metal layer. By using polytetrafluoroethylene having a functional group, even though the dielectric layer is formed of polytetrafluoroethylene, the metal layer and the dielectric layer can be bonded with high peel strength. Furthermore, by using polytetrafluoroethylene having a functional group, even when the surface roughness Rzjis of the metal layer is within the above range, the metal layer and the dielectric layer can be bonded with high peel strength.

[0025] As the functional group that polytetrafluoroethylene has, since the peel strength between the metal layer and the dielectric layer can be further increased, a cyano group (-CN), General formula (1): [Chemical formula] (R

[0026] , , , , 3 and R 2 are each independently a hydrogen atom, a halogen atom, -OR 3 , -N(R 3 )2, -R 3 , and R 3 is an alkyl group that may contain fluorine and has 1 to 10 carbon atoms or a hydrogen atom), the functional group (1) represented by, and General formula (2): [Chemical formula] (R 1 is a hydrogen atom, a halogen atom, -OR<s 3 , -N(R 3 )2, -R 3 , and R 3 is an alkyl group that may contain fluorine and has 1 to 10 carbon atoms or a hydrogen atom), the functional group (2)<0s000222>At least one selected from the group consisting of is preferable.

[0026] Among the functional groups that polytetrafluoroethylene possesses, the functional group represented by general formula (2) is preferred because it can further increase the peel strength between the metal layer and the dielectric layer, and -COOR 3 (R 3 (wherein is a C1-C10 alkyl group or hydrogen atom which may contain fluorine) is more preferably, and at least one selected from the group consisting of -COOH and -COOCH3 is even more preferably.

[0027] The functional group content in polytetrafluoroethylene can further increase the peel strength between the metal layer and the dielectric layer. Therefore, the functional group content is preferably 0.0001 to 2 mol%, more preferably 0.001 mol% or more, even more preferably 0.003 mol% or more, even more preferably 1 mol% or less, even more preferably 0.50 mol% or less, even more preferably 0.30 mol% or less, and particularly preferably 0.20 mol% or less, based on the total monomer units constituting the polytetrafluoroethylene.

[0028] The functional group content in polytetrafluoroethylene can be measured by NMR spectroscopy.

[0029] In one embodiment, a dielectric layer is formed using non-melt-processable polytetrafluoroethylene. This further improves transmission performance. Non-melt-processable means that, in accordance with ASTM D 1238 and D 2116, the melt flow rate cannot be measured at temperatures higher than the crystallization melting point. In other words, non-melt-processable polytetrafluoroethylene does not flow substantially even when heated above its melting point.

[0030] The melting point of polytetrafluoroethylene is preferably 321°C or higher, more preferably 325°C or higher, preferably 350°C or lower, and more preferably 348°C or lower.

[0031] The melting point of polytetrafluoroethylene can be measured by differential thermogravimetric analysis.

[0032] The standard specific gravity (SSG) of polytetrafluoroethylene is preferably 2.130 or higher, more preferably 2.150 or higher, more preferably 2.280 or lower, and more preferably 2.210 or lower.

[0033] The standard specific gravity (SSG) of polytetrafluoroethylene can be measured using a sample prepared in accordance with ASTM D 4895-89 and the water displacement method in accordance with ASTM D 792.

[0034] The functional groups described above can be introduced into polytetrafluoroethylene by using a polymerization initiator or chain transfer agent that can introduce the functional groups described above to the molecular chain ends of polytetrafluoroethylene in a polymerization reaction for producing polytetrafluoroethylene. For example, when a persulfate such as ammonium persulfate is used as a polymerization initiator in a polymerization reaction, -COOH, -COOCH3, etc., can be introduced to the molecular chain ends of polytetrafluoroethylene. 3 (R 3 A functional group represented by (which may contain fluorine or hydrogen atoms with 1 to 10 carbon atoms) can be introduced. Also, -COOR 3 By treating polytetrafluoroethylene having the functional group shown by with ammonia, -COOR 3 The functional group shown can be converted to -CONH2. In this way, for example, the functional group (1) or functional group (2) described above can be introduced to the molecular chain end of polytetrafluoroethylene.

[0035] Furthermore, the functional groups described above can be introduced into polytetrafluoroethylene by copolymerization of tetrafluoroethylene with a monomer containing functional groups. When a monomer containing functional groups is introduced into polytetrafluoroethylene, the functional groups can be introduced along the main chain of the polymer, making it easy to obtain laminates with higher interlayer peel strength compared to cases where functional groups are introduced only at the ends of the molecular chain.

[0036] Examples of monomers having functional groups include monomers having an ethylenically unsaturated bond and at least one selected from the group consisting of a cyano group (-CN), a functional group (1) represented by general formula (1), and a functional group (2) represented by general formula (2).

[0037] The content of units based on monomers having functional groups in polytetrafluoroethylene can further increase the peel strength between the metal layer and the dielectric layer. Therefore, the content is preferably 0.0001 to 2 mol%, more preferably 0.001 mol% or more, even more preferably 0.003 mol% or more, even more preferably 1 mol% or less, even more preferably 0.50 mol% or less, even more preferably 0.30 mol% or less, and particularly preferably 0.20 mol% or less, relative to the total monomer units constituting polytetrafluoroethylene.

[0038] The content of units based on monomers with functional groups in polytetrafluoroethylene can be measured by NMR spectroscopy.

[0039] A monomer having a functional group is the general formula (3): CY 1 Y 2 =CY 3 (O) m (R 8 ) n -Z 1 (3) (In the formula, Y 1 ~Y 3 Each of these is independently a hydrogen atom, a halogen atom, -CH3, or -CF3, and R 8 is a divalent organic group, n is 0 or 1, m is 0 if n is 0, and 0 or 1 if n is 1, Z 1 A monomer represented by a cyano group (-CN), a functional group (1) represented by general formula (1), and a functional group (2) represented by general formula (2) is preferred.

[0040] Y 1 and Y 2As such, fluorine atoms are preferred. Also, Y 3 Fluorine atoms or -CF3 are preferred as the element.

[0041] R 8 Preferably, the alkylene group may contain ether bonds with 1 to 100 carbon atoms. More preferably, the number of carbon atoms is 1 to 50, and even more preferably 1 to 20. In such an alkylene group, some or all of the hydrogen atoms may be substituted with halogen atoms, particularly fluorine atoms. 8 As such, fluorine-containing alkylene groups, which may contain ether bonds having 1 to 10 carbon atoms, are particularly preferred.

[0042] Furthermore, based on the above configuration, the following compounds can be given as examples. CH2=CH-(CF2) n -Z 2 (4) (In the formula, n is an integer between 2 and 8) CY 4 2 = CY 4 (CF2) n -Z 2 (5) (In the formula, Y 4 (where n is a hydrogen atom or a fluorine atom, and n is an integer between 1 and 8) CF2 = CFCF2R f 4 -Z 2 (6) (In the formula, R f 4 ha-(OCF2) n -or-(OCF(CF3)) n - where n is an integer between 0 and 5) CF2 = CFCF2(OCF(CF3)CF2) m (OCH2CF2CF2) n OCH2CF2-Z 2 (7) (In the formula, m is an integer between 0 and 5, and n is an integer between 0 and 5.) CF2 = CFCF2(OCH2CF2CF2) m (OCF(CF3)CF2) n OCF(CF3)-Z2 (8) (In the formula, m is an integer between 0 and 5, and n is an integer between 0 and 5.) CF2 = CF(OCF2CF(CF3)) m O(CF2) n -Z 2 (9) (In the formula, m is an integer between 0 and 5, and n is an integer between 1 and 8.) CF2 = CF(OCF2CF(CF3)) m -Z 2 (10) (In the formula, m is an integer between 1 and 5) CF2 = CFOCF2(CF(CF3)OCF2) n CF(-Z 2 )CF3(11) (In the formula, n is an integer between 1 and 4.) CF2 = CFO(CF2) n OCF(CF3)-Z 2 (12) (In the formula, n is an integer between 2 and 5.) CF2 = CFO(CF2) n -(C6H4)-Z 2 (13) (In the formula, n is an integer between 1 and 6.) CF2 = CF(OCF2CF(CF3)) n OCF2CF(CF3)-Z 2 (14) (In the formula, n is an integer between 1 and 2.) CH2=CFCF2O(CF(CF3)CF2O) n CF(CF3)-Z 2 (15) (In the formula, n is an integer between 0 and 5.) CF2 = CFO(CF2CF(CF3)O) m (CF2) n -Z 2 (16) (In the formula, m is an integer between 0 and 5, and n is an integer between 1 and 3.) CH2 = CFCF2OCF(CF3)OCF(CF3) - Z 2 (17) CH2=CFCF2OCH2CF2-Z 2 (18) CF2=CFO(CF2CF(CF3)O) m CF2CF(CF3)-Z 2 (19) (where m is an integer of 0 or more) CF2=CFOCF(CF3)CF2O(CF2) n -Z 2 (20) (where n is an integer of 1 or more) CF2=CFOCF2OCF2CF(CF3)OCF2-Z 2 (21) CF2=CF-(CF2C(CF3)F) n -Z 2 (22) (where n is an integer of 1 to 5), CF2=CFO-(CFY 5 ) n -Z 2 (23) (where Y 5 is F or -CF3, and n is an integer of 1 to 10) CF2=CFO-(CF2CFY 6 O) m -(CF2) n -Z 2 (24) (where Y 6 is F or -CF3, m is an integer of 1 to 10, and n is an integer of 1 to 3) CH2=CFCF2O-(CF(CF3)CF2O) n -CF(CF3)-Z 2 (25) (where n is an integer of 0 to 10) CF2=CFCF2O-(CF(CF3)CF2O) n -CF(CF3)-Z 2 (26) (where n is an integer of 1 to 10) CF2=C(CF3)-(CF2) n -Z 2 (27) (where n is an integer of 0 to 8) (In general formulas (4) to (27), Z 2(This is one of the functional groups listed above.)

[0043] Specifically, the monomer represented by general formula (5) is: Examples include CF2=CF-CF2-CN, CF2=CF-CF2CF2-CN, CF2=CFCF2-C(=NH)-OR, CF2=CFCF2CF2-C(=NH)-OR, CF2=CF-CF2-COOH, CF2=CF-CF2CF2-COOH, CF2=CF-CF2-COOCH3, and CF2=CF-CF2CF2-COOCH3.

[0044] Specifically, the monomer represented by general formula (22) is: CF2=CFCF2C(CF3)FCN, CF2=CF(CF2C(CF3)F)2CN, CF2=CFCF2C(CF3)FC(=NH)-OR, CF2=CF(CF2C(CF3)F)2-C(=NH)-OR, CF Examples include 2=CFCF2C(CF3)FCOOH, CF2=CF(CF2C(CF3)F)2COOH, CF2=CFCF2C(CF3)FCOOCH3, CF2=CF(CF2C(CF3)F)2COOCH3.

[0045] Specifically, the monomer represented by general formula (23) is: Examples include CF2=CFOCF2CF2CF2CN, CF2=CFOCF2CF2CN, CF2=CFOCF2CN, CF2=CFOCF2CF2CF2-C(=NH)-OR, CF2=CFOCF2CF2-C(=NH)-OR, CF2=CFOCF2-C(=NH)-OR, CF2=CFOCF2CF2CF2COOH, CF2=CFOCF2CF2COOH, CF2=CFOCF2COOH, CF2=CFOCF2CF2CF2COOCH3, CF2=CFOCF2CF2COOCH3, and CF2=CFOCF2COOCH3.

[0046] Specifically, the monomer represented by general formula (24) is: Examples include CF2=CFOCF2CF(CF3)OCF2CF2CN, CF2=CFOCF2CF(CF3)OCF2CF2-C(=NH)-OR, CF2=CFOCF2CF(CF3)OCF2CF2COOH, and CF2=CFOCF2CF(CF3)OCF2CF2COOCH3.

[0047] Specifically, the monomer represented by general formula (25) is: CH2=CFCF2OCF(CF3)CN, CH2=CFCF2OCF(CF3)CF2OCF(CF3)CN, CH2=CFCF2O(CF(CF3)CF2O)2CF(CF3)CN, CH2=CFCF2OCF (CF3)-C(=NH)-OR, CH2=CFCF2OCF(CF3)CF2OCF(CF3)-C(=NH)-OR, CH2=CFCF2O(CF(CF3)CF2O)2CF(CF3)-C(=NH)-OR, C Examples include H2=CFCF2OCF(CF3)COOH, CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOH, CH2=CFCF2O(CF(CF3)CF2O)2CF(CF3)COOH, CH2=CFCF2OCF(CF3)COOCH3, CH2=CFCF2OCF(CF3)CF2OCF(CF3)COOCH3, and CH2=CFCF2O(CF(CF3)CF2O)2CF(CF3)COOCH3.

[0048] Specifically, the monomer represented by general formula (26) is: Examples include CF2=CFCF2OCF(CF3)CF2OCF(CF3)CN, CF2=CFCF2OCF(CF3)CF2OCF(CF3)-C(=NH)-OR, CF2=CFCF2OCF(CF3)CF2OCF(CF3)COOH, and CF2=CFCF2OCF(CF3)CF2OCF(CF3)COOCH3.

[0049] Specifically, the monomer represented by general formula (27) is: CF2=C(CF3)-CN, CF2=C(CF3)-CF2-CN, CF2=C(CF3)-CF2CF2-CN, CF2=C(CF3)-C(=NH)-OR, CF2=C(CF3)CF2-C(=NH)-OR, CF2=C(CF3)CF2CF2-C(=NH)-OR, CF2 =C(CF3)-COOH, CF2=C(CF3)-CF2-COOH, CF2=C(CF3)-CF2CF2-COOH, CF2=C(CF3)-COOCH3, CF2=C(CF3)-CF2-COOCH3, CF2=C(CF3)-CF2CF2-COOCH3 and the like.

[0050] Among the monomers having functional groups, at least one selected from the group consisting of CF2=C(CF3)COOCH3, CF2=CFOCF2CF2COOH, and CF2=CFOCF2C(CF3)FOCF2CF2COOCH3 is preferred, as it can further increase the peel strength between the metal layer and the dielectric layer, and CF2=CFOCF2C(CF3)FOCF2CF2COOCH3 is even more preferred.

[0051] Polytetrafluoroethylene may contain units based on tetrafluoroethylene and monomers other than monomers having functional groups. Preferred monomers other than monomers having functional groups are fluorine-containing monomers (excluding tetrafluoroethylene and monomers having functional groups).

[0052] Examples of fluorine-containing monomers include hexafluoropropylene, chlorotrifluoroethylene, trifluoroethylene, perfluoro(alkyl vinyl ether), perfluoro(alkoxy vinyl ether), and (perfluoroalkyl)ethylene. Among these, at least one selected from the group consisting of hexafluoropropylene and perfluoro(alkyl vinyl ether) is preferred.

[0053] As the perfluoro(alkyl vinyl ether), at least one selected from the group consisting of perfluoro(methyl vinyl ether) [PMVE], perfluoro(ethyl vinyl ether) [PEVE], perfluoro(propyl vinyl ether) [PPVE], and perfluoro(butyl vinyl ether) is preferred.

[0054] The content of units based on other monomers is preferably 0 to 2 mol%, more preferably 0.01 mol% or more, even more preferably 0.03 mol% or more, more preferably 1 mol% or less, and even more preferably 0.50 mol% or less, relative to the total monomer units constituting polytetrafluoroethylene.

[0055] The dielectric layer may contain only polytetrafluoroethylene having functional groups as the polymer, or it may contain polymers other than polytetrafluoroethylene having functional groups. The content of polytetrafluoroethylene having functional groups in the dielectric layer is preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 99% by mass or more, even more preferably 99.9% by mass or more, and preferably 100% by mass or less, when the total amount of polymer contained in the dielectric layer is taken as 100% by mass.

[0056] Polytetrafluoroethylene having functional groups can be produced, for example, by the method described in Japanese Patent Publication No. 2009-44018.

[0057] The dielectric layer may contain inorganic pigments, fillers, adhesion promoters, antioxidants, lubricants, dyes, etc. The inorganic pigment is preferably stable during molding; examples include titanium, iron oxides, and carbon powder.

[0058] In one embodiment, the dielectric layer contains silica. The inclusion of silica in the dielectric layer improves the deformation resistance of the laminate at high temperatures.

[0059] As silica, particulate silica can be used. The average particle size of the silica is preferably 0.1 μm or more, more preferably 1.0 μm or more, more preferably 100 μm or less, more preferably 10 μm or less, and even more preferably 3 μm or less.

[0060] The silica content in the dielectric layer is preferably 10% by mass or more, more preferably 30% by mass, and more preferably 70% by mass or less, relative to the total amount of polytetrafluoroethylene and silica in the dielectric layer.

[0061] In one embodiment, the dielectric layer contains glass cloth or glass nonwoven fabric.

[0062] Suitable materials for the glass cloth include E glass, C glass, A glass, S glass, D glass, NE glass, low dielectric constant glass, and quartz glass, but E glass, S glass, and NE glass are preferred due to their availability. The weave can be plain or twill. The thickness of the glass cloth is usually 5 to 90 μm, preferably 10 to 75 μm. To increase its affinity with polytetrafluoroethylene, the glass cloth may be treated with a silane coupling agent.

[0063] Glass nonwoven fabric is made by fixing short glass fibers with a small amount of binder compound (resin or inorganic substance), or by maintaining its shape by entangling the short glass fibers without using a binder compound. The diameter of the short glass fibers is preferably 0.5 to 30 μm, and the fiber length is preferably 5 to 30 mm. Specific examples of binder compounds include resins such as epoxy resin, acrylic resin, cellulose, polyvinyl alcohol, and fluororesin, as well as inorganic substances such as silica compounds. The amount of binder compound used is usually 3 to 15% by mass relative to the short glass fibers. Examples of materials for the short glass fibers include E glass, C glass, A glass, S glass, D glass, NE glass, low dielectric constant glass, and quartz glass. The thickness of the glass nonwoven fabric is usually 10 to 1000 μm, and preferably 10 to 300 μm. To increase its affinity with polytetrafluoroethylene having functional groups, the glass nonwoven fabric may be treated with a silane coupling agent.

[0064] The dielectric layer may or may not be surface-treated. Examples of surface treatment methods include sodium etching and plasma etching. In one embodiment, the dielectric layer is not surface-treated.

[0065] 3. Laminate The laminate of the present disclosure comprises a metal layer and a dielectric layer, wherein the metal layer and the dielectric layer are directly bonded together. The laminate of the present disclosure may have a metal layer on one side of the dielectric layer, or it may have metal layers on both sides of the dielectric layer.

[0066] The laminates of the present disclosure may include layers other than the metal layer and the dielectric layer. In one embodiment, the laminates of the present disclosure include only the metal layer and the dielectric layer, and no other layers.

[0067] The laminate of this disclosure can be manufactured, for example, by a manufacturing method in which an aqueous dispersion containing polytetrafluoroethylene having functional groups is prepared, a sheet is made by immersing glass cloth or glass nonwoven fabric in the aqueous dispersion and pulling it out, the sheet and metal foil are stacked, and pressure is applied while heating.

[0068] An aqueous dispersion may be prepared by mixing an aqueous medium, polytetrafluoroethylene, and other components such as silica using a mixer or the like. The polytetrafluoroethylene content in the aqueous dispersion may be, for example, 20 to 60% by mass. The operation of immersing the glass cloth or glass nonwoven fabric in the aqueous dispersion and then removing it may be repeated multiple times. Drying or heat treatment may be performed each time the glass cloth or glass nonwoven fabric is removed from the aqueous dispersion. Heating when applying pressure can be carried out, for example, at a temperature above the melting point of polytetrafluoroethylene and below 420°C.

[0069] Furthermore, the laminate of this disclosure can be manufactured, for example, by a manufacturing method in which polytetrafluoroethylene having functional groups is paste-extruded to produce an extruded product, the extruded product is rolled to produce a sheet, the sheet and metal foil are stacked, and pressure is applied while heating.

[0070] The polytetrafluoroethylene and other components such as silica may be mixed using a mixer before paste extrusion molding. The prepared sheet may be heated to volatilize the extrusion aids and low molecular weight components used in paste extrusion molding. In addition to the prepared sheet and metal foil, glass cloth or glass nonwoven fabric may be layered on top and pressure may be applied while heating. The heating when applying pressure can be carried out, for example, at a temperature above the melting point of polytetrafluoroethylene and below 420°C.

[0071] The laminate of the present invention can be suitably used as a printed wiring board. In particular, since the laminate of the present invention has excellent high-frequency signal transmission performance and high reliability, it is suitable as a printed wiring board for high-frequency signal transmission. The frequency of the high-frequency signal may be, for example, 3 GHz or more, 6 GHz or more, or 12 GHz or more, and may be 100 GHz or less.

[0072] As described above, the embodiments have been described, but it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims.

[0073] <1> According to the first aspect of the present disclosure, A laminate comprising a metal layer and a dielectric layer, wherein the dielectric layer contains polytetrafluoroethylene having a functional group, the peel strength between the metal layer and the dielectric layer is 1.0 N / cm or more, and the dielectric tangent of the dielectric layer is 0.0010 or less A laminate is provided. <2> According to the second aspect of the present disclosure, A laminate according to the first aspect, wherein the peel strength between the metal layer and the dielectric layer is 3.0 N / cm or more, is provided. <3> According to the third aspect of the present disclosure, A laminate according to the first or second aspect, wherein the surface roughness (Rzjis) of the metal layer is 4.0 μm or less, is provided. <4> According to the fourth aspect of the present disclosure, A laminate according to any one of the first to third aspects, wherein the polytetrafluoroethylene has non-melt processability, is provided. <5> According to the fifth aspect of the present disclosure, the functional group is a cyano group (-CN), General formula (1):

Chemical formula

[0074] Next, embodiments of the present disclosure will be described with reference to examples, but the present disclosure is not limited to such embodiments.

[0075] 1. Preparation of polytetrafluoroethylene (PTFE) Each value in the examples was measured by the following method.

[0076] <Average primary particle diameter> A PTFE aqueous dispersion was prepared with a solid content concentration of approximately 1.0% by mass, and measured using an ELSZ-1000S (manufactured by Otsuka Electronics Co., Ltd.) at 25°C for 70 cumulative measurements. The refractive index of the solvent (water) was 1.3328, and its viscosity was 0.8878 mPa·s.

[0077] <Melting point> Approximately 10 mg of PTFE powder was accurately weighed and placed in a dedicated aluminum pan. The temperature was then measured using a TG / DTA (Differential Thermal Gravimetric Analysis) device. The peak temperature was determined by obtaining a differential thermal (DTA) curve by heating the aluminum pan in an atmospheric environment from 25°C to 600°C at a rate of 10°C / min, and the peak temperature was defined as the temperature corresponding to the maximum value in the obtained differential thermal (DTA) curve.

[0078] <Standard specific gravity (SSG)> Samples were prepared according to ASTM D 4895-89 and measured using the water displacement method according to ASTM D 792.

[0079] <Amount of denaturation> solid 19 F-MAS NMR measurements (probe diameter: 4.0 mm, rotation speed: 30 kHz, measurement atmosphere: nitrogen, measurement temperature: 150 °C) were used to detect peaks originating from TFE and peaks originating from the denaturing agent, and the results were determined from the area ratio of these peaks.

[0080] <Solid content concentration (P)> 1 g (X) of aqueous PTFE dispersion was placed in a 5 cm diameter aluminum cup, dried at 100°C for 60 minutes, and then dried again at 300°C for 60 minutes. The percentage of P was determined based on the heat residue (Z) using the formula: P = Z / X × 100 (%).

[0081] <Content of nonionic surfactant (N)> The percentage was calculated using the formula: N = [(YZ) / Z] × 100 (%) from the following: 1 g (X) of PTFE aqueous dispersion was placed in a 5 cm diameter aluminum cup and heated at 100°C for 60 minutes to obtain the residual (Y), and then the obtained residual (Y) was heated at 300°C for 60 minutes to obtain the residual (Z).

[0082] <Method for measuring the number of functional units> A film with a thickness of 0.25 to 0.5 mm is prepared by compression molding of PTFE powder at 25°C. The obtained film is analyzed by Fourier transform infrared spectroscopy to obtain a difference spectrum between the infrared absorption spectrum of the fluororesin and the spectrum without functional groups. From the absorption peak of a specific functional group appearing in this difference spectrum, the main chain carbon atoms in PTFE (1 × 10⁶) are determined according to the following formula (A). 6 Calculate the number of functional units N per individual. N = (I × K) / t (A) I: Absorbance K: Correction coefficient t: Film thickness (mm)

[0083] The correction factor for the target terminal group is shown below. This correction factor is 1 × 10¹⁶ carbon atoms in the main chain terminal carbon. 6 The number of functional groups per compound was determined from the infrared absorption vector of the model compound. Functional group Absorption frequency (cm) -1 ) Correction factor -COOH (Free) 1815 439 -COOH (Meeting) 1779 439 -COOCH31795 342 -CONH23436 460

[0084] (Synthesis Example 1) 3560 g of deionized water, 104 g of paraffin wax, and 3.58 g of a white solid obtained by the method described in Synthesis Example 1 of International Publication No. 2021 / 045228 were placed in a 6 L stainless steel reactor equipped with a stirrer. The contents of the reactor were then heated to 70°C while being aspirated, and the reactor was purged with TFE monomer to remove oxygen. Subsequently, 3.0 g of methyl pentafluoromethacrylate (CF2=C(CF3)COOCH3, hereinafter abbreviated as MPFA) was added to the reactor, and the contents were stirred at 280 rpm. TFE monomer was added to the reactor until the pressure reached 0.73 MPa. 0.072 g of ammonium persulfate (APS) initiator dissolved in 20 g of deionized water was injected into the reactor, and the reactor pressure was increased to 0.83 MPa. A decrease in pressure occurred after the injection of the initiator, and the start of polymerization was observed. TFE monomers were added to the reactor and the pressure was maintained. Polymerization continued until approximately 1.1 kg of TFE monomers had reacted. After that, the reactor was evacuated, the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the PTFE aqueous dispersion. The solid content concentration of the obtained PTFE aqueous dispersion (1-1) was 23.1% by mass, and the average primary particle size was 224 nm.

[0085] The obtained PTFE aqueous dispersion (1-1) was diluted with deionized water to a solid content concentration of approximately 15% by mass, and coagulated under high-speed stirring conditions. The coagulated powder was dried at 150°C for 18 hours. At this time, the melting point of the PTFE powder was 331.9°C, the SSG was 2.268, and the MPFA modification amount was 0.006 mol%. The MPFA modification amount was determined by detecting the peak derived from TFE (-150 to -90 ppm) and the peak derived from MPFA (-65 to -63 ppm) and calculating the area ratio of these peaks.

[0086] The resulting aqueous PTFE dispersion (1-1) is mixed with a nonionic surfactant RO(CH2CH2O) nA PTFE aqueous dispersion was prepared by adding H(R: tridecyl group) (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Neugen TDS-80) to a nonionic surfactant concentration of 10 parts by mass per 100 parts by mass of PTFE solids. Subsequently, 250 ml of OH-type anion exchange resin (product name Amberjet 4002, manufactured by Rohm & Haas) was packed into a 20 mm diameter column, and the above PTFE aqueous dispersion was passed through it at SV=1. Furthermore, the nonionic surfactant (Neugen TDS-80) was added to the obtained PTFE aqueous dispersion so that it was 16 parts by mass per 100 parts by mass of PTFE solids, and the mixture was held at 65°C for 3 hours to separate the supernatant phase and the concentrated phase. The concentrated phase was recovered to obtain PTFE aqueous dispersion (1-2). The obtained PTFE aqueous dispersion (1-2) had a solids concentration of 64.1% by mass and an ionic surfactant content of 4.2% by mass relative to the PTFE solids. To the obtained PTFE aqueous dispersion (1-2), a nonionic surfactant (Neugen TDS-80) was added to a concentration of 5.0% by mass relative to the PTFE solids, and then deionized water and ammonia water were added to obtain PTFE aqueous dispersion (1-3). The obtained PTFE aqueous dispersion (1-3) had a solids concentration of 60.0% by mass, and the nonionic surfactant content was 5.0% by mass relative to the PTFE solids.

[0087] (Synthesis Example 2) Polymerization was carried out in the same manner as in Synthesis Example 1, except that 3.0 g of MPFA in Synthesis Example 1 was replaced with 3.0 g of CF2=CFOCF2CF2COOH and 1.08 g of HFP. The resulting aqueous PTFE dispersion (2-1) had a solid content concentration of 23.4% by mass and an average primary particle size of 176 nm.

[0088] The aqueous PTFE dispersion (2-1) obtained in Synthesis Example 2 could be coagulated using the same method as in Synthesis Example 1, and PTFE powder was obtained. The melting point of the obtained PTFE powder was 335.2°C, the SSG was 2.169, the CF2=CFOCF2CF2COOH modification amount was 0.117 mol%, and the HFP modification amount was 0.046 mol%. The CF2=CFOCF2CF2COOH modification amount was determined by detecting peaks derived from TFE (-150 to -90 ppm), peaks derived from CF2=CFOCF2CF2COOH (-89 to -73 ppm, -67 to -63 ppm), and peaks derived from HFP (-66 to -60 ppm), and calculating the area ratio of these peaks.

[0089] The PTFE aqueous dispersion (2-1) obtained in Synthesis Example 2 could be concentrated by the same method as in Synthesis Example 1 to obtain PTFE aqueous dispersion (2-2). The obtained PTFE aqueous dispersion (2-2) had a solid content concentration of 64.7% by mass and an ionic surfactant content of 4.0% by mass relative to the PTFE solid content. The concentration of the obtained PTFE aqueous dispersion (2-2) could be adjusted by the same method as in Synthesis Example 1. The obtained PTFE aqueous dispersion (2-3) had a solid content concentration of 60.0% by mass and a nonionic surfactant content of 5.0% by mass relative to the PTFE solid content.

[0090] (Synthesis Example 3) Polymerization was carried out in the same manner as in Synthesis Example 1, except that 3.0 g of MPFA in Synthesis Example 1 was replaced with 10.0 g of perfluoro[3-(1-methyl-2-vinyloxyethoxy)propionate methyl] (CF2=CFOCF2C(CF3)FOCF2CF2COOCH3, hereinafter abbreviated as RVEE), 0.072 g of APS was replaced with 0.036 g, and approximately 1.1 kg of TFE monomer was converted to approximately 1.5 kg of TFE monomer. The obtained PTFE aqueous dispersion (3-1) had a solid content concentration of 29.2% by mass and an average primary particle size of 217 nm.

[0091] The aqueous PTFE dispersion (3-1) obtained in Synthesis Example 3 could be coagulated using the same method as in Synthesis Example 1, yielding PTFE powder. The melting point of the obtained PTFE powder was 334.8°C, the SSG was 2.183, and the RVEE modification amount was 0.122 mol%. The RVEE modification amount was determined by detecting the peak derived from TFE (-150 to -90 ppm) and the peak derived from RVEE (-85 to -72 ppm) and calculating the area ratio of these peaks.

[0092] The PTFE aqueous dispersion (3-1) obtained in Synthesis Example 3 could be concentrated by the same method as in Synthesis Example 1 to obtain PTFE aqueous dispersion (3-2). The obtained PTFE aqueous dispersion (3-2) had a solid content concentration of 65.2% by mass and an ionic surfactant content of 2.8% by mass relative to the PTFE solid content. The concentration of the obtained PTFE aqueous dispersion (3-2) could be adjusted by the same method as in Synthesis Example 1. The obtained PTFE aqueous dispersion (3-3) had a solid content concentration of 60.0% by mass and a nonionic surfactant content of 5.0% by mass relative to the PTFE solid content.

[0093] (Synthesis Example 4) Polymerization was carried out in the same manner as in Synthesis Example 1, except that 3.0 g of MPFA was omitted and approximately 1.1 kg of TFE monomers were converted to approximately 1.5 kg of TFE monomers. The solid content concentration of the obtained PTFE aqueous dispersion (4-1) was 32.0% by mass, and the average primary particle size was 232 nm.

[0094] The aqueous PTFE dispersion (4-1) obtained in Synthesis Example 4 could be coagulated by the same method as in Synthesis Example 1 to obtain PTFE powder. The melting point of the obtained PTFE powder was 342.5°C, the SSG was 2.208, and the number of terminal functional groups was 1 × 10⁶ carbon atoms in the main chain. 6 There were 9 per unit.

[0095] The PTFE aqueous dispersion (4-1) obtained in Synthesis Example 4 could be concentrated by the same method as in Synthesis Example 1 to obtain PTFE aqueous dispersion (4-2). The obtained PTFE aqueous dispersion (4-2) had a solid content concentration of 64.2% by mass and an ionic surfactant content of 4.2% by mass relative to the PTFE solid content. The concentration of the obtained PTFE aqueous dispersion (4-2) could be adjusted by the same method as in Synthesis Example 1. The obtained PTFE aqueous dispersion (4-3) had a solid content concentration of 60.0% by mass and a nonionic surfactant content of 5.0% by mass relative to the PTFE solid content.

[0096] 2. Fabrication of laminated boards Each value in the examples was measured by the following method.

[0097] <Peel strength> In accordance with JIS C 6481-1996, the 90° peel strength (N / cm) of each test specimen was measured when peeling off the copper foil at a tensile speed of 50 mm / min at a temperature of 25°C.

[0098] <Surface roughness Rzjis> In accordance with JIS B0601-2001, the ten-point average roughness (Rzjis) was measured on the unroughened surface of copper foil. Measurements were taken at five points within the metal foil (using a Keyence VK-X1000 laser microscope with a 50x objective lens) or at five points in the diametrical direction of a metal wire sample (using a Keyence VK-X1000 laser microscope with a 20x objective lens), and the average value was calculated to determine the surface roughness Rzjis.

[0099] <Relative permittivity, dielectric loss tangent> Using a split cylinder manufactured by EM Labs, a PC with its calculation software installed, and a network analyzer, the relative permittivity and dielectric loss tangent were measured at 10 GHz and 25 ± 3°C.

[0100] <Insertion loss (S21)> A coaxial cable with an impedance of approximately 50Ω was created by extruding the resin of the present invention onto a metal core wire with a roughened surface, attaching a metal outer layer, adding a jacket with heat-shrink tubing, and attaching connectors to both ends. Furthermore, the insertion loss (S21) of this coaxial cable was measured at frequencies of 5GHz, 15GHz, 20GHz, and 25GHz at a temperature of 25℃±3℃ using an HP8510 network analyzer manufactured by HP Corporation.

[0101] Example 1 A PTFE aqueous dispersion (3-3) was impregnated into Nitto Boseki Co., Ltd. glass cloth TE1035 in an atmosphere of 25±3℃. The glass cloth was impregnated once on each side. The sheet impregnated with this PTFE dispersion was air-dried at room temperature for 15 minutes and then placed in an electric furnace set to 110℃ for 15 minutes. After that, it was removed from the electric furnace and placed in an electric furnace set to 200℃ for 15 minutes. This process was repeated four times to obtain a four-layer impregnated sheet, which was designated as PTFE impregnated sheet A.

[0102] Furthermore, both sides of PTFE-impregnated sheet A were sandwiched between unroughened copper foil (CF-T9DA-SV, Rzjis 0.11μm, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.) with a chemically treated surface, placed on a hot plate press, and subjected to a reduced pressure of 900 mm / Hg or higher for 1 minute, followed by pressing at 360°C for 15 minutes at 15kN. This laminated sheet D was cut into 10mm widths, and a 90-degree peel strength test was performed, yielding a result of 14N / 10mm.

[0103] Separately, PTFE-impregnated sheet A was further treated in an electric furnace at 360°C for 15 minutes. This sheet is designated as PTFE-impregnated fired sheet B.

[0104] The electrical properties of this PTFE-impregnated fired sheet B were measured using the split-cylinder method at 10 GHz and 25°C, and the relative permittivity was 2.2 and the dielectric loss tangent was 0.0008.

[0105] Example 2 1000 g of PTFE powder obtained from the aqueous PTFE dispersion (3-1) was mixed with 190 g of a hydrocarbon solvent (product name: Isopar G, manufactured by ExxonMobil) as an extrusion aid. This mixed paste was paste-extruded into a 2 mm thick, 100 mm wide sheet to obtain PTFE fine powder sheet C. This PTFE fine powder sheet C was then rolled using a 300 mm diameter metal roll to obtain PTFE fine powder sheet D with a thickness of 150 ± 20 μm. This PTFE fine powder sheet D was heated in an electric furnace at 200 °C for 15 minutes. This is designated as PTFE fine powder sheet E.

[0106] Both outer surfaces of a PTFE fine powder sheet E were sandwiched between un-roughened copper foil with a surface roughness of 0.14 μm and no chemical treatment on the surface. The sheet was then placed on a hot plate press, reduced pressure to over 900 mm / Hg for 1 minute, and then pressed at 360°C for 15 minutes at 15 kN. The peel strength was 3.8 N / cm.

[0107] Separately, PTFE fine powder sheet E was further treated in an electric furnace at 360°C for 15 minutes. This sheet is designated as PTFE fine powder sheet G.

[0108] The electrical properties of this PTFE fine powder sheet G were measured using the split-cylinder method at 10 GHz and 25°C, and the relative permittivity was found to be 2.1 and the dielectric loss tangent was 0.0006.

[0109] Example 3 1000 g of PTFE powder obtained from the aqueous PTFE dispersion (3-1) was mixed with 190 g of isoper G, a hydrocarbon solvent used as an extrusion aid. This mixed paste was extruded into a 2 mm thick, 100 mm wide sheet to obtain PTFE fine powder sheet F. This PTFE fine powder sheet F was then rolled using a 300 mm diameter metal roll to obtain PTFE fine powder sheet J with a thickness of 150 ± 20 μm. This PTFE fine powder sheet J was heated in an electric furnace at 200 °C for 15 minutes. This is referred to as PTFE fine powder sheet K.

[0110] Both outer sides of a PTFE fine powder sheet K were sandwiched between unroughened copper foil (CF-T9DA-SV, Rzjis 0.11 μm, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.), placed on a hot plate press, and subjected to a reduced pressure of 900 mm / Hg or higher for 1 minute. Subsequently, the sheet was pressed at 360°C for 15 minutes at 15 kN. A 90-degree peel strength test was then performed using the resulting sheet. The peel strength was 12 N / cm.

[0111] The PTFE fine powder sheet K was further treated in an electric furnace at 360°C for 15 minutes. This sheet is designated as PTFE fine powder sheet L.

[0112] The electrical properties of this PTFE fine powder sheet L were measured using the 10 GHz split-cylinder method, and the relative permittivity was found to be 2.1 and the dielectric loss tangent was 0.0006.

[0113] Example 4 1000 g of PTFE powder obtained from PTFE aqueous dispersion (1-1) was mixed with 190 g of isoper G, a hydrocarbon solvent used as an extrusion aid. This mixed paste was extruded into a 2 mm thick, 100 mm wide sheet to obtain PTFE fine powder sheet M. This PTFE fine powder sheet M was then rolled using a 300 mm diameter metal roll to obtain PTFE fine powder sheet N with a thickness of 150 ± 20 μm. This PTFE fine powder sheet N was heated in an electric furnace at 200 °C for 15 minutes. This is referred to as PTFE fine powder sheet P.

[0114] Both outer surfaces of a PTFE fine powder sheet P were sandwiched between unroughened copper foil (CF-T9DA-SV, Rzjis 0.11 μm, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.), placed on a hot plate press, and subjected to a reduced pressure of 900 mm / Hg or higher for 1 minute, followed by pressing at 360°C for 15 minutes at 15 kN. This pressed sheet was designated Q. The peel strength was 7.1 N / cm.

[0115] Separately, PTFE fine powder sheet P was further treated in an electric furnace at 360°C for 15 minutes. This sheet is referred to as PTFE fine powder sheet S.

[0116] The electrical properties of this PTFE fine powder sheet S were measured using the 10 GHz split-cylinder method, and the relative permittivity was found to be 2.1 and the dielectric loss tangent was 0.0006.

[0117] Example 5 1000 g of PTFE powder obtained from the aqueous PTFE dispersion (3-1) was mixed with 190 g of isoper G, a hydrocarbon solvent used as an extrusion aid. This mixed paste was extruded into a 16 mm diameter rod to obtain a PTFE fine powder rod T. The PTFE fine powder rod T was rolled using a 300 mm diameter metal roll to obtain a PTFE fine powder sheet U with a thickness of 150 ± 20 μm. This PTFE fine powder sheet U was heated in an electric furnace at 200 °C for 15 minutes. This is designated as PTFE fine powder sheet V.

[0118] A PTFE fine powder sheet V was placed on both sides of a glass cloth TE1035 manufactured by Nitto Boseki Co., Ltd., and then sandwiched on both sides with unroughened copper foil (CF-T9DA-SV, Rzjis 0.11 μm, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.). The sheet was placed on a hot plate press, the pressure was reduced to over 900 mm / Hg for 1 minute, and then it was pressed at 360°C for 15 minutes at 15 kN. The resulting sheet was then used to perform a 90-degree peel strength test. The peel strength was 12.0 N / cm.

[0119] Separately, PTFE fine powder sheet V was further treated in an electric furnace at 360°C for 15 minutes. This sheet is designated as PTFE fine powder sheet X.

[0120] The electrical properties of this PTFE fine powder sheet X were measured using the split cylinder method, and the relative permittivity was found to be 2.3 and the dielectric loss tangent was 0.0007.

[0121] Example 6 400 g of PTFE powder obtained from the aqueous PTFE dispersion (3-1) was mixed with 600 g of silica powder with an average particle size of 2 μm and 190 g of isoper G, a hydrocarbon solvent used as an extrusion aid. This mixed paste was extruded into a 2 mm thick, 100 mm wide sheet to obtain PTFE fine powder sheet Y. This PTFE fine powder sheet Y was then rolled using a 300 mm diameter metal roll to obtain PTFE fine powder sheet Z with a thickness of 150 ± 20 μm. This PTFE fine powder sheet Z was heated in an electric furnace at 200 °C for 15 minutes. This is referred to as PTFE fine powder sheet AA.

[0122] A PTFE fine powder sheet AA was placed on both sides of a glass cloth TE1035 manufactured by Nitto Boseki Co., Ltd., and then sandwiched on both sides with unroughened copper foil (CF-T9DA-SV, Rzjis 0.11 μm, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.). The sheet was placed on a hot plate press, the pressure was reduced to over 900 mm / Hg for 1 minute, and then it was pressed at 360°C for 15 minutes at 15 kN. The resulting sheet was then subjected to a 90-degree peel strength test. The peel strength was 14 N / cm. This sheet is designated as PTFE fine powder sheet AB.

[0123] Separately, PTFE fine powder sheet AA was further treated in an electric furnace at 360°C for 15 minutes. This sheet is designated as PTFE fine powder sheet AC.

[0124] The electrical properties of this PTFE fine powder sheet AC were measured using the 10 GHz split-cylinder method, and the relative permittivity was found to be 2.6 and the dielectric loss tangent was 0.0008.

[0125] Comparative Example 1 A PTFE aqueous dispersion (4-3) was impregnated into Nitto Boseki Co., Ltd. glass cloth TE1035 in an atmosphere of 25±3℃. The glass cloth was impregnated once on both sides. The sheet impregnated with this PTFE dispersion was air-dried at room temperature for 15 minutes, and then placed in an electric furnace set to 110℃ for 15 minutes. After that, it was removed from the electric furnace and placed in an electric furnace set to 200℃ for 5 minutes. This process was repeated four times to obtain a four-layer impregnated sheet, which was designated as PTFE impregnated sheet AF.

[0126] Furthermore, both sides of the PTFE-impregnated sheet AF were sandwiched between unroughened copper foil (CF-T9DA-SV, Rzjis 0.11μm, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.), placed on a hot plate press, and subjected to a reduced pressure of 900 mm / Hg or higher for 1 minute, followed by pressing at 360°C for 15 minutes at 15kN. When this laminated sheet AF2 was cut into 10 mm widths and subjected to a 90-degree peel strength test, the result was 0.9 N / 10 mm.

[0127] The PTFE-impregnated sheet AF was further treated in an electric furnace at 360°C for 15 minutes. This sheet is designated as the PTFE-impregnated fired sheet AG.

[0128] The electrical properties of this PTFE-impregnated fired sheet AG were measured using the 10 GHz split-cylinder method, and the relative permittivity was found to be 2.2 and the dielectric loss tangent was 0.0008.

[0129] Comparative Example 2 1000 g of PTFE powder obtained from PTFE aqueous dispersion (4-1) was mixed with 190 g of isoper G, a hydrocarbon solvent used as an extrusion aid. This mixed paste was extruded into a 2 mm thick, 100 mm wide sheet to obtain PTFE fine powder sheet AH. This PTFE fine powder sheet AH was then rolled using a 300 mm diameter metal roll to obtain PTFE fine powder sheet AJ with a thickness of 150 ± 20 μm. This PTFE fine powder sheet AJ was heated in an electric furnace at 200 °C for 15 minutes. This is designated as PTFE fine powder sheet AK.

[0130] A PTFE fine powder sheet AK was sandwiched between two layers of un-roughened copper foil with a surface roughness of 0.14 μm and no chemical treatment on the surface. The sheet was placed on a hot plate press, and the pressure was reduced to over 900 mm / Hg for 1 minute, followed by pressing at 360°C for 15 minutes at 15 kN. This pressed sheet was designated AN, and its peel strength was measured to be 0.3 N / cm.

[0131] Separately, PTFE fine powder sheet AK was further treated in an electric furnace at 360°C for 15 minutes. This sheet is designated as PTFE fine powder sheet AN.

[0132] The electrical properties of this PTFE fine powder sheet AN were measured using the 10 GHz split-cylinder method, and the relative permittivity was found to be 2.2 and the dielectric loss tangent was 0.0008.

[0133] Comparative Example 3 1000 g of PTFE powder obtained from PTFE aqueous dispersion (4-1) was mixed with 190 g of isoper G, a hydrocarbon solvent used as an extrusion aid. This mixed paste was paste-extruded into a 2 mm thick, 100 mm wide sheet to obtain PTFE fine powder sheet AP. This PTFE fine powder sheet AP was then rolled using a 300 mm diameter metal roll to obtain PTFE fine powder sheet AQ with a thickness of 150 ± 20 μm. This PTFE fine powder sheet AQ was heated in an electric furnace at 200 °C for 15 minutes. This was designated as PTFE fine powder sheet AR. Both sides of this sheet were sandwiched between unroughened copper foil with a surface roughness of 0.14 μm and an untreated surface. The sheet was placed on a hot plate press, reduced pressure to over 900 mm / Hg for 1 minute, and then pressed at 360 °C for 15 minutes at 15 kN. The peel strength of this pressed sheet was measured to be 0.9 N / cm.

[0134] The PTFE fine powder sheet AR was further treated in an electric furnace at 360°C for 15 minutes. This sheet is designated as the PTFE fine powder sheet AS.

[0135] The electrical properties of this PTFE fine powder sheet AS were measured using the split cylinder method, and the relative permittivity was found to be 2.1 and the dielectric loss tangent was 0.0006.

[0136] Comparative Example 4 400 g of PTFE powder obtained from PTFE aqueous dispersion (4-1) was mixed with 600 g of silica powder with an average particle size of 2 μm and 190 g of isoper G, a hydrocarbon solvent used as an extrusion aid. This mixed paste was extruded into a 2 mm thick, 100 mm wide sheet to obtain PTFE fine powder sheet AT. This PTFE fine powder sheet AT was then rolled using a 300 mm diameter metal roll to obtain PTFE fine powder sheet AU with a thickness of 150 ± 20 μm. This PTFE fine powder sheet AU was heated in an electric furnace at 200 °C for 15 minutes. This was designated as PTFE fine powder sheet AV. Both sides of AV were sandwiched between unroughened copper foil (CF-T9DA-SV, Rzjis 0.11 μm, manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd.), placed on a hot plate press, and subjected to a reduced pressure of 900 mm / Hg or higher for 1 minute, followed by pressing at 360 °C for 15 minutes at 15 kN. The peel strength of this press sheet was measured to be 0.9 N / cm.

[0137] The PTFE fine powder sheet AV was further treated in an electric furnace at 360°C for 15 minutes. This sheet is designated as PTFE fine powder sheet AW.

[0138] The electrical properties of this PTFE fine powder sheet AW were measured using the split cylinder method, and the relative permittivity was found to be 2.6 and the dielectric loss tangent was 0.0008.

[0139] Comparative Example 5 1000 g of PTFE powder obtained from PTFE aqueous dispersion (4-1) was mixed with 190 g of isoper G, a hydrocarbon solvent used as an extrusion aid. This mixed paste was extruded into a 2 mm thick, 100 mm wide sheet to obtain PTFE fine powder sheet AX. This PTFE fine powder sheet AX was then rolled using a 300 mm diameter metal roll to obtain PTFE fine powder sheet AY with a thickness of 150 ± 20 μm. This PTFE fine powder sheet AY was heated in an electric furnace at 200 °C for 15 minutes. This is designated as PTFE fine powder sheet AZ. PTFE fine powder sheet AZ was placed on a hot plate press, reduced in pressure to over 900 mm / Hg for 1 minute, and then pressed at 360 °C for 15 minutes at 15 kN to bake. This sheet is designated as PTFE fine powder sheet BA.

[0140] A hydrophilization treatment was performed on PTFE fine powder sheet BA by immersion in a solution containing a metallic sodium-naphthalene complex. Tetraetch (product name) manufactured by Junko Co., Ltd. was used. The hydrophilization treatment was carried out at a treatment temperature of 25°C for 5 seconds. (In this process, fluorine atoms are removed from the surface of PTFE fine powder sheet BA by the metallic sodium-naphthalene complex solution, and hydrophilic groups mainly consisting of hydroxyl groups are introduced in their place.) The sheet that underwent the immersion treatment was designated as PTFE fine powder sheet BB. Both sides of PTFE fine powder sheet BB were sandwiched between unroughened copper foil with a surface roughness of 0.14 μm and an untreated surface, and placed on a hot plate press. The pressure was reduced to 900 mm / Hg or higher for 1 minute, and then pressed at 360°C for 15 minutes at 15 kN. The peel strength of this pressed sheet was measured to be 20.4 N / cm.

[0141] The PTFE fine powder sheet BA was further treated in an electric furnace at 360°C for 15 minutes. This sheet is designated as PTFE fine powder sheet BC.

[0142] The electrical properties of this PTFE fine powder sheet BC were measured using the split cylinder method, and the relative permittivity was found to be 2.2 and the dielectric loss tangent was 0.0012.

[0143] The results are shown in Tables 1 and 2.

[0144] [Table 1]

[0145] [Table 2]

[0146] Experimental Example 1 The surface of a 1mm diameter copper wire was roughened with 240-grit sandpaper. The Rzjis was measured to be 8.04 μm. A paste was prepared by mixing PTFE powder obtained from an aqueous PTFE dispersion (3-1) with 21% by mass of an extrusion aid (product name: Isopar G, manufactured by ExxonMobil). The prepared paste was extruded onto the obtained copper wire, coated by drying with an auxiliary agent and firing, and then covered with a shielding braided wire and secured with heat shrink tubing to create a coaxial cable with an impedance close to 50Ω. The insertion loss at 20GHz was measured with a network analyzer and was -18.9dB / 900mm.

[0147] Experimental Example 2 Experimental Example 1 involved changing the sandpaper grit to 2000. The Rzjis measurement was 2.00 μm. The insertion loss was -14.8 dB / 900 mm.

[0148] Experimental Example 3 A 1mm diameter copper wire was used as is. The Rzjis was measured to be 0.92 μm. The insertion loss at 20 GHz was -12.4 dB / 900 mm.

[0149] The results are shown in Table 3.

[0150] [Table 3]

[0151] The results shown in Table 3 indicate that coaxial cables with metal wires having lower surface roughness exhibit higher insertion loss. Therefore, it can be seen that the transmission performance of the laminate can be improved by reducing the surface roughness of the metal layer of the laminate.

Claims

1. A laminate comprising a metal layer and a dielectric layer, The dielectric layer contains polytetrafluoroethylene having functional groups, The peel strength between the metal layer and the dielectric layer is 1.0 N / cm or more. The dielectric loss tangent of the dielectric layer is 0.0010 or less. The polytetrafluoroethylene has non-melt processability. Laminated board.

2. The laminate according to claim 1, wherein the peel strength between the metal layer and the dielectric layer is 3.0 N / cm or more.

3. The laminate according to claim 1 or 2, wherein the surface roughness (Rzjis) of the metal layer is 4.0 μm or less.

4. The aforementioned functional group is a cyano group (-CN), General formula (1): 【Transformation 5】 (R １ and R ２ Each is independently a hydrogen atom, a halogen atom, and -OR ３ , -N(R ３ ) ２ , -R ３ And R ３ (1) is a functional group (which may contain fluorine or hydrogen atoms having 1 to 10 carbon atoms), and General formula (2): 【Transformation 6】 (R １ is a hydrogen atom, a halogen atom, -OR ３ , -N(R ３ ), -R ２ , and R ３ is an alkyl group which may contain fluorine and has 1 to 10 carbon atoms or a hydrogen atom), and the functional group (2) represented by ３ ​ The laminate according to claim 1 or 2, which is at least one selected from the group consisting of the following.

5. The laminate according to claim 1 or 2, wherein the content of the functional group in the polytetrafluoroethylene is 0.0001 to 2 mol% with respect to the total monomer units constituting the polytetrafluoroethylene.

6. The laminate according to claim 1 or 2, wherein the surface of the metal layer is chemically treated.

7. The laminate according to claim 1 or 2, wherein the metal layer is a copper layer.

8. A printed wiring board formed from a laminate according to claim 1 or 2.

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