Laminate

Abstract

Provided is a laminate comprising a metal layer and a dielectric layer, wherein the dielectric layer contains polytetrafluoroethylene having a functional group, and 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

Laminated board

[0001] The present disclosure relates to laminates.

[0002] Patent Document 1 describes a material for printed circuit boards that contains 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 polytetrafluoroethylene crosslinked body obtained by crosslinking the crosslinkable polytetrafluoroethylene.

[0003] JP 2009-44018 A

[0004] An object of the present disclosure is to provide a laminate comprising a metal layer and a dielectric layer, in which the peel strength between the layers is high and the dielectric tangent of the dielectric layer is low.

[0005] According to the present disclosure, there is provided 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.

[0006] According to the present disclosure, it is possible to provide a laminate plate that includes a metal layer and a dielectric layer, has high interlayer peel strength, and has a low dielectric loss tangent of the dielectric layer.

[0007] Specific embodiments of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments.

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

[0009] 1. Metal Layer The laminate of the present disclosure includes a metal layer. Examples of metals that form the metal layer include copper, stainless steel, aluminum, iron, and alloys thereof. Among these, at least one metal selected from the group consisting of copper and aluminum is preferred, and copper is 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 wiring 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] The surface roughness (Rzjis) can be measured in accordance with JIS B0601-2001.

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

[0014] 2. Dielectric Layer The laminate of the present disclosure includes a dielectric layer, and the metal layer and the dielectric layer are directly bonded to each other.

[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 although there is no particular limitation on the lower limit, it 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 layers constituting the laminate and recovering only the dielectric layer, and then 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 forming the dielectric layer, the heating temperature, heating rate, number of heating cycles, etc. for the dielectric layer.

[0017] The laminate of the present disclosure includes a dielectric layer with a low dielectric tangent, and therefore when the laminate of the present 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 an increase in transmission loss of high frequency signals in the dielectric layer, which in turn reduces transmission loss of high frequency signals in the metal layer.

[0019] Furthermore, as described above, when 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 dielectric constant of the dielectric layer is preferably 2.1 to 2.6. The dielectric constant of the dielectric layer is the dielectric constant of the dielectric layer alone. The dielectric constant of the dielectric layer can be measured by removing the metal layers constituting the laminate and recovering only the dielectric layer, and then measuring the recovered dielectric layer by the split cylinder method at 10 GHz and 25±3°C.

[0021] In the laminate of the present disclosure, the peel strength between the metal layer and the dielectric layer is 1.0 N / cm or more, preferably 3.0 N / cm or more, more preferably 7.0 N / cm or more, and even more preferably 10.0 N / cm or more, and although there is no particular upper limit, it 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 setting the peel strength between the metal layer and the dielectric layer within the above range, excellent transmission performance can be maintained for a long period of time, ensuring high reliability. If the peel strength between the metal layer and the dielectric layer is too low, problems such as peeling of the metal layer during use can occur when the laminate of the present disclosure is used as a printed wiring board, impairing the excellent transmission performance.

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

[0025] The functional groups contained in polytetrafluoroethylene are preferably a cyano group (—CN), a group represented by the general formula (1): (R １ and R ２ are each independently a hydrogen atom, a halogen atom, or —OR ３ , -N(R ３ ) ２ , -R ３ and R ３ is a C1 to C10 alkyl group which may contain fluorine or a hydrogen atom), and a functional group (1) represented by general formula (2): (R １ is a hydrogen atom, a halogen atom, -OR ３ , -N(R ３ ) ２ , -R ３ and R ３is a C1-10 alkyl group which may contain fluorine or a hydrogen atom),

[0026] Among these, the functional group of polytetrafluoroethylene is preferably the functional group represented by the general formula (2) because it can further increase the peel strength between the metal layer and the dielectric layer, and is -COOR ３ (R ３ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may contain fluorine), and —COOH and —COOCH ３ More preferably, at least one selected from the group consisting of:

[0027] The content of functional groups in polytetrafluoroethylene is preferably 0.0001 to 2 mol %, more preferably 0.001 mol % or more, even more preferably 0.003 mol % or more, more preferably 1 mol % or less, even more preferably 0.50 mol % or less, still more preferably 0.30 mol % or less, and particularly preferably 0.20 mol % or less, relative to all monomer units constituting polytetrafluoroethylene, because this can further increase the peel strength between the metal layer and the dielectric layer.

[0028] The content of functional groups in polytetrafluoroethylene can be measured by NMR measurement.

[0029] In one embodiment, the dielectric layer is formed of non-melt-processible polytetrafluoroethylene, which can further improve transmission performance. Non-melt-processible means that the melt flow rate cannot be measured at a temperature higher than the crystallization melting point in accordance with ASTM D 1238 and D 2116. In other words, non-melt-processible polytetrafluoroethylene does not substantially flow 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, and preferably 350° C. or lower, more preferably 348° C. or lower.

[0031] The melting point of polytetrafluoroethylene can be measured by simultaneous differential scanning calorimetry and thermogravimetry.

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

[0033] The standard specific gravity (SSG) of polytetrafluoroethylene can be measured by the water displacement method according to ASTM D 792 using a sample molded according to ASTM D 4895-89.

[0034] The above-mentioned functional groups can be introduced into polytetrafluoroethylene by using a polymerization initiator or chain transfer agent capable of introducing the above-mentioned functional groups into the molecular chain terminals of polytetrafluoroethylene in the polymerization reaction for producing polytetrafluoroethylene. For example, when a persulfate such as ammonium persulfate is used as the polymerization initiator in the polymerization reaction, -COOH, -COOCH ３ -COOR etc. ３ (R ３ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms which may contain fluorine. ３ By treating polytetrafluoroethylene having a functional group represented by -COOR with ammonia, ３ The functional group represented by -CONH ２ In this way, for example, the above-mentioned functional group (1) or functional group (2) can be introduced into the molecular chain terminal of polytetrafluoroethylene.

[0035] The above-mentioned functional groups can be introduced into polytetrafluoroethylene by copolymerizing tetrafluoroethylene with a monomer having a functional group. When a monomer having a functional group is introduced into polytetrafluoroethylene, the functional group can be introduced along the main chain of the polymer, and therefore a laminate having a higher interlayer peel strength can be easily obtained compared to when the functional group is introduced only at the molecular chain end.

[0036] Examples of the monomer having a functional group include a monomer 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 is preferably 0.0001 to 2 mol %, more preferably 0.001 mol % or more, even more preferably 0.003 mol % or more, more preferably 1 mol % or less, even more preferably 0.50 mol % or less, still more preferably 0.30 mol % or less, and particularly preferably 0.20 mol % or less, relative to all monomer units constituting polytetrafluoroethylene, because this can further increase the peel strength between the metal layer and the dielectric layer.

[0038] The content of units based on a monomer having a functional group in polytetrafluoroethylene can be measured by NMR measurement.

[0039] The monomer having a functional group includes a monomer represented by the general formula (3): CY １ Y ２ =CY ３ (O) ｍ (R ８ ) ｎ -Z １ (3) (wherein, Y １ ~Y ３ are each independently a hydrogen atom, a halogen atom, or —CH ３ , or -CF ３ and R ８ is a divalent organic group, n is 0 or 1, m is 0 when n is 0, and 0 or 1 when n is 1, Z １ is 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).

[0040] Y １ and Y ２ A fluorine atom is preferred as Y. ３is a fluorine atom or —CF ３ is preferred.

[0041] R ８ As R, an alkylene group having 1 to 100 carbon atoms which may contain an ether bond is preferred. The number of carbon atoms is more preferably 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 the alkylene group, a fluorine-containing alkylene group having 1 to 10 carbon atoms which may contain an ether bond is particularly preferred.

[0042] In addition, from the above-mentioned structure, the following compound can be exemplified as an example: CH ２ =CH-(CF ２ ) ｎ -Z ２ (4) (wherein n is an integer of 2 to 8) CY ４ ２ =CY ４ (CF ２ ) ｎ -Z ２ (5) (wherein, Y ４ is a hydrogen atom or a fluorine atom, and n is an integer of 1 to 8) CF ２ =CFCF ２ R ｆ ４ -Z ２ (6) (wherein, R ｆ ４ Ha-(OCF ２ ) ｎ - or - (OCF (CF ３ )) ｎ -, and n is an integer from 0 to 5) CF ２ =CFCF ２ (OCF (CF ３ )CF ２ ) ｍ (OCH ２ CF ２ CF ２ ) ｎ OCH ２ CF ２ -Z ２ (7) (wherein m is an integer from 0 to 5, and n is an integer from 0 to 5) CF２ =CFCF ２ (OCH ２ CF ２ CF ２ ) ｍ (OCF (CF ３ )CF ２ ) ｎ OCF (CF ３ )-Z ２ (8) (wherein m is an integer of 0 to 5, and n is an integer of 0 to 5) CF ２ =CF(OCF ２ CF (CF ３ )) ｍ O (CF ２ ) ｎ -Z ２ (9) (wherein m is an integer of 0 to 5, and n is an integer of 1 to 8) CF ２ =CF(OCF ２ CF (CF ３ )) ｍ -Z ２ (10) CF (wherein m is an integer from 1 to 5) ２ = CFOCF ２ (CF (CF ３ ) OCF ２ ) ｎ CF(-Z ２ )CF ３ (11) CF (wherein n is an integer from 1 to 4) ２ = CFO (CF ２ ) ｎ OCF (CF ３ )-Z ２ (12) CF (wherein n is an integer from 2 to 5) ２ = CFO (CF ２ ) ｎ -(C ６ H ４ )-Z ２ (13) CF (wherein n is an integer from 1 to 6) ２ =CF(OCF ２ CF (CF ３ )) ｎ OCF ２ CF (CF ３ )-Z ２ (14) (wherein n is an integer of 1 to 2) CH ２=CFCF ２ O(CF(CF ３ )CF ２ O) ｎ CF (CF ３ )-Z ２ (15) (wherein n is an integer from 0 to 5), CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ (CF ２ ) ｎ -Z ２ (16) (wherein m is an integer of 0 to 5, and n is an integer of 1 to 3) CH ２ =CFCF ２ OCF (CF ３ ) OCF (CF ３ )-Z ２ (17) CH ２ =CFCF ２ OCH ２ CF ２ -Z ２ (18) CF ２ = CFO (CF ２ CF (CF ３ ) O) ｍ CF ２ CF (CF ３ )-Z ２ (19) (wherein m is an integer of 0 or more) CF ２ = CFOCF(CF ３ )CF ２ O (CF ２ ) ｎ -Z ２ (20) (wherein n is an integer of 1 or more) CF ２ = CFOCF ２ OCF ２ CF (CF ３ ) OCF ２ -Z ２ (21) CF ２ =CF-(CF ２ C (CF ３ ) F) ｎ -Z ２ (22) (wherein n is an integer from 1 to 5), CF ２ = CFO - (CFY ５ ) ｎ -Z２ (23) (wherein, Y ５ is F or -CF ３ and n is an integer from 1 to 10. ２ = CFO-(CF ２ CFY ６ O) ｍ -(CF ２ ) ｎ -Z ２ (24) (wherein, Y ６ is F or -CF ３ wherein m is an integer from 1 to 10, and n is an integer from 1 to 3. ２ =CFCF ２ O-(CF(CF ３ )CF ２ O) ｎ -CF (CF ３ )-Z ２ (25) (wherein n is an integer from 0 to 10) CF ２ =CFCF ２ O-(CF(CF ３ )CF ２ O) ｎ -CF (CF ３ )-Z ２ (26) CF (wherein n is an integer from 1 to 10) ２ = C(CF ３ )-(CF ２ ) ｎ -Z ２ (27) (wherein n is an integer of 0 to 8) (in the general formulas (4) to (27), Z ２ is any of the above functional groups)

[0043] Specific examples of the monomer represented by the general formula (5) include: ２ =CF-CF ２ -CN,CF ２ =CF-CF ２ CF ２ -CN,CF ２ =CFCF ２ -C(=NH)-OR, CF ２ =CFCF ２ CF ２ -C(=NH)-OR, CF ２ =CF-CF ２ -COOH, CF２ =CF-CF ２ CF ２ -COOH, CF ２ =CF-CF ２ -COOCH ３ , C.F. ２ =CF-CF ２ CF ２ -COOCH ３ Examples include:

[0044] Specific examples of the monomer represented by the general formula (22) include: ２ =CFCF ２ C (CF ３ ) FCN, CF ２ =CF(CF ２ C (CF ３ ) F) ２ C.N., C.F. ２ =CFCF ２ C (CF ３ )FC(=NH)-OR, CF ２ =CF(CF ２ C (CF ３ ) F) ２ -C(=NH)-OR, CF ２ =CFCF ２ C (CF ３ ) FCOOH, CF ２ =CF(CF ２ C (CF ３ ) F) ２ COOH, C.F. ２ =CFCF ２ C (CF ３ ) FCOOCH ３ , C.F. ２ =CF(CF ２ C (CF ３ ) F) ２ COOCH ３ Examples include:

[0045] Specific examples of the monomer represented by the general formula (23) include: ２ = CFOCF ２ CF ２ CF ２ C.N., C.F. ２ = CFOCF ２ CF ２ C.N., C.F. ２ = CFOCF２ C.N., C.F. ２ = CFOCF ２ CF ２ CF ２ -C(=NH)-OR, CF ２ = CFOCF ２ CF ２ -C(=NH)-OR, CF ２ = CFOCF ２ -C(=NH)-OR, CF ２ = CFOCF ２ CF ２ CF ２ COOH, C.F. ２ = CFOCF ２ CF ２ COOH, C.F. ２ = CFOCF ２ COOH, C.F. ２ = CFOCF ２ CF ２ CF ２ COOCH ３ , C.F. ２ = CFOCF ２ CF ２ COOCH ３ , C.F. ２ = CFOCF ２ COOCH ３ Examples include:

[0046] Specific examples of the monomer represented by the general formula (24) include: ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ C.N., C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ -C(=NH)-OR, CF ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOH, C.F. ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ COOCH ３Examples include the following.

[0047] As the monomer represented by the general formula (25), specifically, CH ２ =CF CF ２ OCF(CF ３ )CN, CH ２ =CF CF ２ OCF(CF ３ )CF ２ OCF(CF ３ )CN, CH ２ =CF CF ２ O(CF(CF ３ )CF ２ O) ２ CF(CF ３ )CN, CH ２ =CF CF ２ OCF(CF ３ )-C(=NH)-OR, CH ２ =CF CF ２ OCF(CF ３ )CF ２ OCF(CF ３ )-C(=NH)-OR, CH ２ =CF CF ２ O(CF(CF ３ )CF ２ O) ２ CF(CF ３ )-C(=NH)-OR, CH ２ =CF CF ２ OCF(CF ３ )COOH, CH ２ =CF CF ２ OCF(CF ３ )CF ２ OCF(CF ３ )COOH, CH ２ =CF CF ２ O(CF(CF ３ )CF ２ O) ２ CF(CF ３ )COOH, CH ２ =CF CF ２ OCF(CF ３ )COOCH ３ , CH ２ =CF CF ２ OCF(CF ３ )CF ２ OCF(CF３ ) COOCH ３ , C.H. ２ =CFCF ２ O(CF(CF ３ )CF ２ O) ２ CF (CF ３ ) COOCH ３ Examples include:

[0048] Specific examples of the monomer represented by the general formula (26) include: ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) CN, CF ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ )-C(=NH)-OR, CF ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COOH, CF ２ =CFCF ２ OCF (CF ３ )CF ２ OCF (CF ３ ) COOCH ３ Examples include:

[0049] Specific examples of the monomer represented by the general formula (27) include: ２ = C(CF ３ )-CN, CF ２ = C(CF ３ )-CF ２ -CN,CF ２ = C(CF ３ )-CF ２ CF ２ -CN,CF ２ = C(CF ３ )-C(=NH)-OR, CF ２ = C(CF ３ )CF ２ -C(=NH)-OR, CF ２ = C(CF ３ )CF ２ CF ２-C(=NH)-OR, CF ２ = C(CF ３ )-COOH, CF ２ = C(CF ３ )-CF ２ -COOH, CF ２ = C(CF ３ )-CF ２ CF ２ -COOH, CF ２ = C(CF ３ )-COOCH ３ , C.F. ２ = C(CF ３ )-CF ２ -COOCH ３ , C.F. ２ = C(CF ３ )-CF ２ CF ２ -COOCH ３ Examples include:

[0050] Among the monomers having functional groups, CF is particularly preferred because it can further increase the peel strength between the metal layer and the dielectric layer. ２ = C(CF ３ ) COOCH ３ , C.F. ２ = CFOCF ２ CF ２ COOH and CF ２ = CFOCF ２ C (CF ３ ) FOCF ２ CF ２ COOCH ３ At least one selected from the group consisting of CF ２ = CFOCF ２ C (CF ３ ) FOCF ２ CF ２ COOCH ３ is more preferable.

[0051] Polytetrafluoroethylene may contain units based on a monomer other than tetrafluoroethylene and a monomer having a functional group. As the monomer other than the monomer having a functional group, a fluorine-containing monomer (excluding tetrafluoroethylene and a monomer having a functional group) is preferred.

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

[0053] The perfluoro(alkyl vinyl ether) is preferably 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).

[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, based on the total monomer units constituting polytetrafluoroethylene.

[0055] The dielectric layer may contain only polytetrafluoroethylene having a functional group as a polymer, or may contain a polymer other than polytetrafluoroethylene having a functional group. The content of polytetrafluoroethylene having a functional group 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, still more preferably 99.9% by mass or more, and preferably 100% by mass or less, when the polymer contained in the dielectric layer is 100% by mass.

[0056] Polytetrafluoroethylene having a functional group can be produced, for example, by the method described in JP-A-2009-44018.

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

[0058] In one embodiment, the dielectric layer contains silica, which improves the laminate's resistance to deformation at high temperatures.

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

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

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

[0062] Examples of glass cloth materials include E-glass, C-glass, A-glass, S-glass, D-glass, NE-glass, low-dielectric-constant glass, and quartz glass, with E-glass, S-glass, and NE-glass being preferred due to their ease of availability. The fiber may be woven in either a plain weave or a twill weave. The thickness of the glass cloth is usually 5 to 90 μm, and preferably 10 to 75 μm. To enhance affinity with polytetrafluoroethylene, the glass cloth may be treated with a silane coupling agent.

[0063] A glass nonwoven fabric is a fabric in which short glass fibers are fixed together with a small amount of a binder compound (resin or inorganic substance), or in which the shape is maintained by entanglement of the short glass fibers without the use of 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 typically 3 to 15 mass% of 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 typically 10 to 1,000 μm, preferably 10 to 300 μm. To enhance affinity with polytetrafluoroethylene having functional groups, the glass nonwoven fabric may be treated with a silane coupling agent.

[0064] The dielectric layer may be surface-treated or may be untreated. Surface treatment methods include sodium etching, plasma etching, etc. In one embodiment, the dielectric layer is untreated.

[0065] 3. Laminate The laminate of the present disclosure includes a metal layer and a dielectric layer, and the metal layer and the dielectric layer are directly bonded to each other. The laminate of the present disclosure may include a metal layer on one side of the dielectric layer, or may include a metal layer on both sides of the dielectric layer.

[0066] The laminate of the present disclosure may include layers other than the metal layer and the dielectric layer, hi one embodiment, the laminate of the present disclosure does not include any other layers and includes only the metal layer and the dielectric layer.

[0067] The laminate of the present disclosure can be produced, for example, by a production method in which an aqueous dispersion containing polytetrafluoroethylene having functional groups is prepared, glass cloth or glass nonwoven fabric is immersed in the aqueous dispersion and then pulled out to form a sheet, and the sheet and metal foil are stacked together 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 a glass cloth or glass nonwoven fabric in the aqueous dispersion and then pulling it up may be repeated multiple times. Each time the glass cloth or glass nonwoven fabric is pulled up from the aqueous dispersion, it may be dried or heat-treated. Heating when applying pressure may be performed at a temperature between the melting point of polytetrafluoroethylene and 420°C.

[0069] Furthermore, the laminate of the present disclosure can be produced, for example, by a production method in which polytetrafluoroethylene having functional groups is paste-extruded to produce an extrudate, the extrudate 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 or the like, followed by paste extrusion molding. The prepared sheet may be heated to volatilize the extrusion aids and low-molecular-weight components used in the paste extrusion molding. A glass cloth or glass nonwoven fabric may be layered on top of the prepared sheet and metal foil, and pressure may be applied while heating. Heating during pressure application may be performed, 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, the laminate of the present invention is suitable as a printed wiring board for transmitting high-frequency signals because it combines excellent high-frequency signal transmission performance with high reliability. 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] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims.

[0073] <1> According to a first aspect of the present disclosure, there is provided a laminate including 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 layer has a dielectric dissipation factor of 0.0010 or less. <2> According to a second aspect of the present disclosure, there is provided 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. <3> According to a third aspect of the present disclosure, there is provided a laminate according to the first or second aspect, wherein the metal layer has a surface roughness (Rzjis) of 4.0 μm or less. <4> According to a fourth aspect of the present disclosure, there is provided a laminate according to any one of the first to third aspects, wherein the polytetrafluoroethylene is non-melt-processable. <5> According to a fifth aspect of the present disclosure, there is provided a laminate according to the first aspect, wherein the functional group is a cyano group (—CN), a fluorine-containing compound represented by general formula (1): (R １ and R ２ are each independently a hydrogen atom, a halogen atom, or —OR ３ , -N(R ３ ) ２ , -R ３ and R ３ is a C1 to C10 alkyl group which may contain fluorine or a hydrogen atom), and a functional group (1) represented by general formula (2): (R １ is a hydrogen atom, a halogen atom, -OR ３ , -N(R ３ ) ２ , -R ３ and R ３(2) wherein the functional group (C) is at least one selected from the group consisting of a C1 to C10 alkyl group which may contain fluorine or a hydrogen atom. <6> According to a sixth aspect of the present disclosure, there is provided a laminate according to any one of the first to fifth aspects, wherein the content of the functional group in the polytetrafluoroethylene is 0.0001 to 2 mol % based on all monomer units constituting the polytetrafluoroethylene. <7> According to a seventh aspect of the present disclosure, there is provided a laminate according to any one of the first to sixth aspects, wherein the surface of the metal layer is chemically treated. <8> According to an eighth aspect of the present disclosure, there is provided a laminate according to any one of the first to seventh aspects, wherein the metal layer is a copper layer. <9> According to a ninth aspect of the present disclosure, there is provided a printed wiring board formed from the laminate according to any one of the first to eighth aspects.

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

[0075] 1. Preparation of Polytetrafluoroethylene (PTFE) The values ​​in the examples were measured by the following methods.

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

[0077] <Melting point> Approximately 10 mg of PTFE powder was weighed out and placed in a dedicated aluminum pan, and the melting point was measured using a TG / DTA (thermogravimetric / differential thermal analyzer). The aluminum pan was heated in an air atmosphere from 25°C to 600°C at a rate of 10°C / min to obtain a differential thermal (DTA) curve, and the peak temperature was determined as the temperature corresponding to the maximum value in the obtained differential thermal (DTA) curve.

[0078] <Standard Specific Gravity (SSG)> Using a sample molded in accordance with ASTM D 4895-89, the standard specific gravity was measured by the water displacement method in accordance with ASTM D 792.

[0079] <Amount of modification> Solid １９ A peak derived from TFE and a peak derived from the modifier were detected by F-MAS NMR measurement (probe diameter: 4.0 mm, rotation speed: 30 KHz, measurement atmosphere: nitrogen, measurement temperature: 150°C), and the ratio was calculated from the area ratio of these peaks.

[0080] <Solid content concentration (P)> 1 g of the aqueous PTFE dispersion (X) was placed in an aluminum cup having a diameter of 5 cm, dried at 100°C for 60 minutes, and further dried at 300°C for 60 minutes to obtain a heating residue (Z). Based on this, the solid content concentration (P) was determined by the formula: P = Z / X × 100 (%).

[0081] <Nonionic surfactant content (N)> 1 g of the aqueous PTFE dispersion (X) was placed in an aluminum cup having a diameter of 5 cm and heated at 100°C for 60 minutes to obtain a heating residue (Y). The heating residue (Y) thus obtained was then heated at 300°C for 60 minutes to obtain a heating residue (Z). From this, the nonionic surfactant content (N) was calculated from the formula: N=[(Y-Z) / Z]×100(%).

[0082] <Method for measuring the number of functional groups> PTFE powder is compression molded at 25°C to produce a film with a thickness of 0.25 to 0.5 mm. 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 in which no functional groups are present. From the absorption peaks of specific functional groups that appear in this difference spectrum, the number of main chain carbon atoms in PTFE is calculated according to the following formula (A): ６ The number of functional groups per molecule, N, is calculated as follows: N = (I x K) / t (A), where I is absorbance, K is correction coefficient, and t is film thickness (mm).

[0083] The correction factor for the target terminal group is shown below. This correction factor is 1 x 10 ６ The functional group absorption frequency (cm) was determined from the infrared absorption spectrum of a model compound to calculate the functional group per unit area. －１ ) Correction coefficient -COOH (free) 1815 439 -COOH (associated) 1779 439 -COOCH ３ 1795 342 -CONH２ 3436 460

[0084] (Synthesis Example 1) 3,560 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 WO 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 simultaneously purged with TFE monomer to remove oxygen from the reactor. Then, 3.0 g of methyl pentafluoromethacrylate (CF ２ = C(CF ３ ) COOCH ３ (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 adjusted to 0.83 MPa. After the initiator injection, a drop in pressure occurred and the initiation of polymerization was observed. TFE monomer was added to the reactor to maintain the pressure, and polymerization was continued until approximately 1.1 kg of TFE monomer had completely reacted. Thereafter, the reactor was vented, and the contents were removed from the reactor and cooled. The supernatant paraffin wax was removed from the PTFE aqueous dispersion. The solids concentration of the resulting PTFE aqueous dispersion (1-1) was 23.1 mass %, and the average primary particle size was 224 nm.

[0085] The resulting PTFE aqueous dispersion (1-1) was diluted with deionized water to a solids concentration of approximately 15% by mass and coagulated under high-speed stirring conditions. The coagulated powder was dried at 150°C for 18 hours. The melting point of the PTFE powder at this time 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 TFE-derived peak (-150 to -90 ppm) and the MPFA-derived peak (-65 to -63 ppm) and calculating the area ratio of these peaks.

[0086] The resulting PTFE aqueous dispersion (1-1) was mixed with a nonionic surfactant RO(CH ２ CH ２ O) ｎH (R: tridecyl group) (product name: Noigen TDS-80, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to prepare an aqueous PTFE dispersion with a nonionic surfactant concentration of 10 parts by mass per 100 parts by mass of PTFE solids. Subsequently, a 20 mm diameter column was filled with 250 ml of OH-type anion exchange resin (trade name: Amberjet 4002, manufactured by Rohm and Haas Co.), and the aqueous PTFE dispersion was passed through at an SV of 1. Furthermore, a nonionic surfactant (Noigen TDS-80) was added to the aqueous PTFE dispersion obtained after passing through the column so that the concentration was 16 parts by mass per 100 parts by mass of PTFE solids, and the mixture was maintained at 65°C for 3 hours, allowing the dispersion to separate into a supernatant phase and a concentrated phase. The concentrated phase was recovered, yielding aqueous PTFE dispersion (1-2). The resulting 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. A nonionic surfactant (Noigen TDS-80) was added to the resulting PTFE aqueous dispersion (1-2) so that the content was 5.0% by mass relative to the PTFE solids, and deionized water and aqueous ammonia were further added to obtain a PTFE aqueous dispersion (1-3). The resulting PTFE aqueous dispersion (1-3) had a solids concentration of 60.0% by mass and a nonionic surfactant content of 5.0% by mass relative to the PTFE solids.

[0087] (Synthesis Example 2) 3.0 g of MPFA in Synthesis Example 1 was mixed with 3.0 g of CF ２ = CFOCF ２ CF ２ Except for using 1.08 g of COOH and 1.08 g of HFP, polymerization was carried out in the same manner as in Synthesis Example 1. The solids concentration of the resulting PTFE aqueous dispersion (2-1) was 23.4 mass %, and the average primary particle size was 176 nm.

[0088] The PTFE aqueous dispersion (2-1) obtained in Synthesis Example 2 could be coagulated in the same manner as in Synthesis Example 1 to obtain a PTFE powder. The melting point of the obtained PTFE powder was 335.2°C, the SSG was 2.169, and the CF ２ = CFOCF ２ CF ２ The amount of COOH modification was 0.117 mol %, and the amount of HFP modification was 0.046 mol %. ２ = CFOCF２ CF ２ The amount of COOH modification is determined by the peaks derived from TFE (-150 to -90 ppm) and CF ２ = CFOCF ２ CF ２ Peaks derived from COOH (-89 to -73 ppm, -67 to -63 ppm) and peaks derived from HFP (-66 to -60 ppm) were detected, and the ratio was calculated from the area 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, and an aqueous PTFE dispersion (2-2) could be obtained. The resulting aqueous PTFE dispersion (2-2) had a solids concentration of 64.7% by mass and an ionic surfactant content of 4.0% by mass relative to the PTFE solids. The concentration of the resulting aqueous PTFE dispersion (2-2) could be adjusted by the same method as in Synthesis Example 1. The resulting aqueous PTFE dispersion (2-3) had a solids concentration of 60.0% by mass and a nonionic surfactant content of 5.0% by mass relative to the PTFE solids.

[0090] (Synthesis Example 3) 3.0 g of MPFA in Synthesis Example 1 was dissolved in 10.0 g of perfluoro[methyl 3-(1-methyl-2-vinyloxy-ethoxy)propionate] (CF ２ = CFOCF ２ C (CF ３ ) FOCF ２ CF ２ COOCH ３ Polymerization was carried out in the same manner as in Synthesis Example 1, except that the amount of RVEE was changed from 0.072 g to 0.036 g, and the amount of TFE monomer was changed from about 1.1 kg to about 1.5 kg. The solids concentration of the resulting PTFE aqueous dispersion (3-1) was 29.2 mass%, and the average primary particle size was 217 nm.

[0091] The PTFE aqueous dispersion (3-1) obtained in Synthesis Example 3 can be coagulated by the same method as in Synthesis Example 1, and PTFE powder can be obtained. The melting point of the obtained PTFE powder is 334.8 ° C, SSG is 2.183, and the RVEE modification amount is 0.122 mol%. The RVEE modification amount is determined by detecting the peak derived from TFE (-150 to -90 ppm) and the peak derived from RVEE (-85 to -72 ppm), and then determining 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, and an aqueous PTFE dispersion (3-2) could be obtained. The resulting aqueous PTFE dispersion (3-2) had a solids concentration of 65.2 mass% and an ionic surfactant content of 2.8 mass% based on the PTFE solids. The concentration of the resulting aqueous PTFE dispersion (3-2) could be adjusted by the same method as in Synthesis Example 1. The resulting aqueous PTFE dispersion (3-3) had a solids concentration of 60.0 mass% and a nonionic surfactant content of 5.0 mass% based on the PTFE solids.

[0093] Synthesis Example 4 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 not added and the amount of TFE monomer was changed from about 1.1 kg to about 1.5 kg. The solids concentration of the resulting aqueous PTFE dispersion (4-1) was 32.0% by mass, and the average primary particle diameter was 232 nm.

[0094] The PTFE aqueous dispersion (4-1) obtained in Synthesis Example 4 could be coagulated in the same manner as in Synthesis Example 1 to obtain a PTFE powder. The resulting PTFE powder had a melting point of 342.5°C, an SSG of 2.208, and the number of terminal functional groups was 1 x 10, the number of carbon atoms in the main chain. ６ There were nine per piece.

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

[0096] 2. Preparation of Laminated Plates The values ​​in the examples were measured by the following methods.

[0097] <Peel Strength> The 90° peel strength (N / cm) was measured according to JIS C 6481-1996 when the copper foil of each test piece was peeled off at a temperature of 25° C. at a pulling rate of 50 mm / min.

[0098] <Surface roughness Rzjis> According to JIS B0601-2001, the ten-point average roughness (Rzjis) was measured on the unroughened surface of the copper foil. The measurement was performed at five points on the metal foil (using a Keyence VK-X1000 laser microscope with a 50x objective lens) or at five points in the diameter 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 be the surface roughness Rzjis.

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

[0100] <Insertion Loss (S21)> A coaxial cable having an impedance of approximately 50 Ω was produced by extruding the resin of the present invention onto a metal core wire with a roughened surface, attaching a metal outer layer, jacketing it with a heat-shrinkable tube, and attaching connectors to both ends. The insertion loss (S21) of this coaxial cable was measured using an HP8510 network analyzer manufactured by HP at frequencies of 5 GHz, 15 GHz, 20 GHz, and 25 GHz at a temperature of 25°C ± 3°C.

[0101] Example 1: PTFE aqueous dispersion (3-3) was impregnated into glass cloth TE1035 manufactured by Nitto Boseki Co., Ltd. in an atmosphere of 25±3°C. 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 at 110°C for 15 minutes. The sheet was then removed from the electric furnace and placed in an electric furnace set at 200°C for 15 minutes. This process was repeated four times to obtain a four-layer impregnated sheet, which was designated PTFE-impregnated sheet A.

[0102] In addition, both sides of the PTFE-impregnated sheet A were sandwiched between unroughened copper foil (CF-T9DA-SV, Rzjis 0.11 μm, manufactured by Fukuda Metal Foil Powder Co., Ltd.) whose surface had been chemically treated, placed on a hot plate press, and the pressure was reduced to 900 mm / Hg or more for 1 minute, followed by pressing at 15 kN for 15 minutes at 360° C. This laminated sheet D was cut into 10 mm wide pieces and subjected to a 90-degree peel strength test, which was found to be 14 N / 10 mm.

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

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

[0105] Example 2 190 g of a hydrocarbon solvent (trade name: Isopar G, manufactured by ExxonMobil Corporation) serving as an extrusion aid was mixed with 1000 g of the PTFE powder obtained from the PTFE aqueous dispersion (3-1). This mixed paste was paste extrusion molded into a 2 mm thick, 100 mm long sheet to obtain PTFE fine powder sheet C. This PTFE fine powder sheet C was then rolled using a metal roll with a diameter of 300 mm 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 PTFE fine powder sheet E.

[0106] The PTFE fine powder sheet E was sandwiched on both outer sides with unroughened copper foil having a surface roughness of 0.14 μm and no chemically treated surface, placed on a hot plate press, and reduced in pressure to 900 mm / Hg or more for 1 minute, after which it was 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 was designated PTFE fine powder sheet G.

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

[0109] Example 3 190 g of the hydrocarbon solvent Isopar G, an extrusion aid, was mixed with 1000 g of the PTFE powder obtained from the PTFE aqueous dispersion (3-1). This mixed paste was paste extrusion molded into a 2 mm thick, 100 mm long sheet to obtain PTFE fine powder sheet F. This PTFE fine powder sheet F was then rolled using a metal roll with a diameter of 300 mm 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 designated PTFE fine powder sheet K.

[0110] The PTFE fine powder sheet K was sandwiched between unroughened copper foil (CF-T9DA-SV, Rzjis 0.11 μm, manufactured by Fukuda Metal Foil and Powder Co., Ltd.) on both sides, placed on a hot plate press, and reduced in pressure to 900 mm / Hg or more for 1 minute. It was then pressed at 360°C for 15 minutes at 15 kN. The resulting sheet was subjected to a 90-degree peel strength test. 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 was designated as PTFE fine powder sheet L.

[0112] The electrical properties of this PTFE fine powder sheet L were measured by a 10 GHz split cylinder method, and the relative dielectric constant was 2.1 and the dielectric loss tangent was 0.0006.

[0113] Example 4 190 g of the hydrocarbon solvent Isopar G, an extrusion aid, was mixed with 1000 g of the PTFE powder obtained from the PTFE aqueous dispersion (1-1). This mixed paste was paste extrusion molded into a 2 mm thick, 100 mm long sheet to obtain PTFE fine powder sheet M. This PTFE fine powder sheet M was then rolled using a metal roll with a diameter of 300 mm 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 designated PTFE fine powder sheet P.

[0114] The PTFE fine powder sheet P was sandwiched on both sides with unroughened copper foil (CF-T9DA-SV, Rzjis 0.11 μm, manufactured by Fukuda Metal Foil Powder Co., Ltd.), placed on a hot plate press, and the pressure was reduced to 900 mm / Hg or more for 1 minute, after which it was pressed at 360°C for 15 minutes at 15 kN. This pressed sheet is designated Q. The peel strength was 7.1 N / cm.

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

[0116] The electrical properties of this PTFE fine powder sheet S were measured by a 10 GHz split cylinder method, and the relative dielectric constant was 2.1 and the dielectric loss tangent was 0.0006.

[0117] Example 5: 190 g of the hydrocarbon solvent Isopar G, an extrusion aid, was mixed with 1000 g of the PTFE powder obtained from the PTFE aqueous dispersion (3-1). This mixed paste was paste extrusion molded into a round bar with a diameter of 16 mm, to obtain a PTFE fine powder round bar T. The PTFE fine powder round bar T was rolled using a metal roll with a diameter of 300 mm, 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] PTFE fine powder sheets V were placed on both sides of glass cloth TE1035 manufactured by Nitto Boseki Co., Ltd., and both sides were sandwiched between unroughened copper foil (CF-T9DA-SV, Rzjis 0.11 μm manufactured by Fukuda Metal Foil and Powder Co., Ltd.), placed on a hot plate press, reduced pressure to 900 mm / Hg or more for 1 minute, and then pressed at 360°C for 15 minutes at 15 kN. Using the resulting sheet, a 90-degree peel strength test was performed. 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 was designated PTFE fine powder sheet X.

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

[0121] Example 6: 400 g of PTFE powder obtained from PTFE aqueous dispersion (3-1) was mixed with 600 g of silica powder with an average particle size of 2 μm and 190 g of hydrocarbon solvent Isopar G as an extrusion aid. This mixed paste was paste extrusion molded into a 2 mm thick, 100 mm long sheet to obtain PTFE fine powder sheet Y. This PTFE fine powder sheet Y was further rolled with 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 designated PTFE fine powder sheet AA.

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

[0124] The electrical properties of this PTFE fine powder sheet AC were measured by the 10 GHz split cylinder method, and the relative dielectric constant was 2.6 and the dielectric loss tangent was 0.0008.

[0125] Comparative Example 1: PTFE aqueous dispersion (4-3) was impregnated into glass cloth TE1035 manufactured by Nitto Boseki Co., Ltd. in an atmosphere of 25±3°C. The front and back of the glass cloth were each impregnated once. The sheet impregnated with this PTFE dispersion was air-dried at room temperature for 15 minutes and then placed in an electric furnace set at 110°C for 15 minutes. It was then removed from the electric furnace and placed in an electric furnace set at 200°C for 5 minutes. This process was repeated four times to obtain a four-layer impregnated sheet, designated PTFE-impregnated sheet AF.

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

[0128] The electrical properties of this PTFE-impregnated sintered sheet AG were measured by the 10 GHz split cylinder method, and the relative dielectric constant was 2.2 and the dielectric loss tangent was 0.0008.

[0129] Comparative Example 2: 190 g of the hydrocarbon solvent Isopar G, an extrusion aid, was mixed with 1000 g of the PTFE powder obtained from the PTFE aqueous dispersion (4-1). This mixed paste was paste extrusion molded into a 2 mm thick, 100 mm long 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 PTFE fine powder sheet AK.

[0130] Both sides of the PTFE fine powder sheet AK were sandwiched between unroughened copper foils with a surface roughness of 0.14 μm and no chemical treatment on the surface, placed on a hot plate press, reduced in pressure to 900 mm / Hg or more for 1 minute, and then pressed at 15 kN for 15 minutes at 360° C. This pressed sheet was designated AN, and the peel strength was measured to be 0.3 N / cm.

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

[0132] The electrical properties of this PTFE fine powder sheet AN were measured by the 10 GHz split cylinder method, and the relative dielectric constant was 2.2 and the dielectric loss tangent was 0.0008.

[0133] Comparative Example 3: 190 g of the hydrocarbon solvent Isopar G, an extrusion aid, was mixed with 1000 g of PTFE powder obtained from the PTFE aqueous dispersion (4-1). This mixed paste was paste extrusion molded into a 2 mm thick, 100 mm long sheet to obtain a PTFE fine powder sheet AP. This PTFE fine powder sheet AP was then rolled using a 300 mm diameter metal roll to obtain a 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 outer surfaces of the sheet were sandwiched between unroughened copper foils with a surface roughness of 0.14 μm and no chemically treated surfaces, placed on a hot plate press, and decompressed at 900 mm / Hg or higher for 1 minute. Then, the sheet was pressed at 360 °C for 15 minutes at 15 kN. The peel strength of this pressed sheet was measured and found 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 was designated as PTFE fine powder sheet AS.

[0135] The electrical properties of this PTFE fine powder sheet AS were measured by the split cylinder method, and the relative dielectric constant was 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 the hydrocarbon solvent Isopar G as an extrusion aid. This mixed paste was paste extrusion molded into a 2 mm thick, 100 mm long sheet to obtain PTFE fine powder sheet AT. This PTFE fine powder sheet AT was then rolled with 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 is designated PTFE fine powder sheet AV. Both sides were sandwiched with unroughened copper foil (CF-T9DA-SV, Rzjis 0.11 μm, manufactured by Fukuda Metal Foil Powder Co., Ltd.), placed on a hot plate press, reduced pressure to 900 mm / Hg or more for 1 minute, and then pressed at 360°C for 15 minutes at 15 kN. The peel strength of this pressed sheet was measured and found 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 was designated as PTFE fine powder sheet AW.

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

[0139] Comparative Example 5: 190 g of the hydrocarbon solvent Isopar G, an extrusion aid, was mixed with 1000 g of PTFE powder obtained from the PTFE aqueous dispersion (4-1). This mixed paste was paste extrusion molded into a 2 mm thick, 100 mm long sheet to obtain PTFE fine powder sheet AX. This PTFE fine powder sheet AX was then rolled with 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 referred to as PTFE fine powder sheet AZ. The PTFE fine powder sheet AZ was placed on a hot plate press and reduced in pressure to 900 mm / Hg or more for 1 minute. It was then pressed at 360 ° C for 15 minutes at 15 kN and sintered. This sheet is referred to as PTFE fine powder sheet BA.

[0140] A hydrophilic treatment process was performed by immersing the PTFE fine powder sheet BA in a solution containing a metallic sodium-naphthalene complex. Tetra-Etch (trade name) manufactured by Junkosha was used. The hydrophilic treatment process was performed at a treatment temperature of 25°C for 5 seconds. (In this process, fluorine atoms are removed from the surface of the PTFE fine powder sheet BA by the metallic sodium-naphthalene complex solution, and hydrophilic groups, primarily hydroxyl groups, are introduced instead.) The sheet that underwent the water immersion treatment was designated PTFE fine powder sheet BB. The PTFE fine powder sheet BB was sandwiched on both outer sides with unroughened copper foil having a surface roughness of 0.14 μm and no chemically treated surface. The sheet was placed on a hot plate press and subjected to a reduced pressure of 900 mm / Hg or greater for 1 minute. It was 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 was designated as PTFE fine powder sheet BC.

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

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

[0144]

[0145]

[0146] Experimental Example 1: The surface of a 1 mm diameter copper wire was roughened with 240-grit sandpaper. The Rzjis was measured to be 8.04 μm. 21% by mass of an extrusion aid (trade name: Isopar G, manufactured by ExxonMobil) was mixed with the PTFE powder obtained from the PTFE aqueous dispersion (3-1) to prepare a paste. The prepared paste was extruded onto the obtained copper wire, and the extrusion aid was dried and baked to form a coating. A shielding braided wire was placed on the outside and pressed down with a heat-shrinkable tube to prepare a coaxial cable with an impedance close to 50 Ω. The insertion loss at 20 GHz was measured using a network analyzer and was found to be -18.9 dB / 900 mm.

[0147] Experimental Example 2: The sandpaper roughness of Experimental Example 1 was changed to 2000. The Rzjis was measured to be 2.00 μm. The insertion loss was −14.8 dB / 900 mm.

[0148] Experimental Example 3 A copper wire with a diameter of 1 mm 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]

[0151] From the results shown in Table 3, the coaxial cable with metal wires having a lower surface roughness exhibits a higher insertion loss, which indicates 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, 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.

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 laminate according to any one of claims 1 to 3, wherein the polytetrafluoroethylene is non-melt processable.

5. The functional group is a cyano group (—CN), a compound represented by the general formula (1): (R １ and R ２ are each independently a hydrogen atom, a halogen atom, or —OR ３ , -N(R ３ ) ２ , -R ３ and R ３ is a C1 to C10 alkyl group which may contain fluorine or a hydrogen atom), and a functional group (1) represented by general formula (2): (R １ is a hydrogen atom, a halogen atom, -OR ３ , -N(R ３ ) ２ , -R ３ and R ３ (2) wherein the functional group is at least one selected from the group consisting of a C1-C10 alkyl group which may contain fluorine or a hydrogen atom.

6. A laminate according to any one of claims 1 to 5, wherein the content of said functional groups in said polytetrafluoroethylene is 0.0001 to 2 mol % based on the total monomer units constituting said polytetrafluoroethylene.

7. The laminate according to any one of claims 1 to 6, wherein the surface of the metal layer is chemically treated.

8. The laminate according to any one of claims 1 to 7, wherein the metal layer is a copper layer.

9. A printed wiring board formed from the laminate according to any one of claims 1 to 8.

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