CN112203844A - Method for producing metal foil with resin and metal foil with resin - Google Patents

Abstract

The present invention provides an efficient method for producing a resin-attached metal foil which has electrical properties and mechanical strength, is useful for the production of printed circuit boards, has a highly homogeneous resin layer containing a fluoropolymer and is not easily warped, and a resin-attached metal foil. metal foil. A method for producing a metal foil with a resin is a method for producing a metal foil with a resin having a resin layer on the surface of the metal foil, wherein the surface of the metal foil is coated with powder dispersion containing a powder of a tetrafluoroethylene-based polymer and a solvent liquid, wherein the tetrafluoroethylene-based polymer has a temperature range showing a storage modulus of 0.1 to 5.0 MPa at 260°C or lower, and a melting point greater than 260°C, and the metal foil is maintained at a temperature within the above temperature range, and further at a temperature greater than 260°C. The tetrafluoroethylene-based polymer is fired at a temperature within the above-mentioned temperature range to form a resin layer containing the tetrafluoroethylene-based polymer on the surface of the metal foil.

Description

Method for producing metal foil with resin and metal foil with resin

Technical Field

The present invention relates to a method for producing a metal foil with resin and a metal foil with resin.

Background

A resin-attached metal foil having an insulating resin layer on a surface thereof is used as a printed circuit board by processing the metal foil by etching or the like.

A printed circuit board for transmitting high-frequency signals is required to have excellent transmission characteristics. In order to improve transmission characteristics, it is necessary to use a resin having a small relative dielectric constant and a small dielectric loss tangent as an insulating resin layer of a printed circuit board. As a resin having a small relative permittivity and a small dielectric loss tangent, a fluoropolymer such as Polytetrafluoroethylene (PTFE) is known.

As a material for forming a resin-attached metal foil having a resin layer containing a fluoropolymer, a powder dispersion liquid in which a fluoropolymer powder is dispersed in a solvent has been proposed (see patent documents 1 and 2).

The powder dispersion has the following advantages: when other insulating resin and varnish are blended, various physical properties of the obtained resin-attached metal foil can be arbitrarily adjusted. In addition, the powder dispersion has the following advantages: the metal foil with the resin can be formed by simply coating the surface of the metal foil and drying the coating.

Documents of the prior art

Patent document

Patent document 1: international publication No. 2017/222027

Patent document 2: international publication No. 2016/159102

Disclosure of Invention

Technical problem to be solved by the invention

As a manufacturing form of the printed circuit board, there are the following forms: a configuration in which another substrate (prepreg or the like) is laminated on the surface of a resin layer (insulating resin layer) containing a fluoropolymer, and a resin-containing metal foil is multilayered; and a form in which another substrate (a cover film or the like) is laminated on the surface of the resin layer to perform sealing. In this case, from the viewpoint of electrical characteristics and productivity of the printed circuit board, it is necessary to laminate the resin layer and another substrate without warping the resin-attached metal foil.

A method of subjecting a resin-bearing metal foil having a resin layer containing a fluoropolymer to surface treatment (plasma treatment, corona treatment, electron beam treatment, or the like) to control warpage of the resin layer is known, but this method requires subjecting the resin-bearing metal foil to surface treatment separately. Further, the surface treatment may induce modification of the resin layer over time, shape change, or the like, and deteriorate the homogeneity of the resin layer.

The present inventors have conducted extensive studies to produce a resin-attached metal foil which has a highly homogeneous resin layer containing a fluoropolymer and is less likely to warp from a powder dispersion containing a fluoropolymer powder. As a result, it has been found that the resin-coated metal foil can be efficiently produced by adjusting the physical properties of the fluoropolymer and the production conditions of the resin-coated metal foil.

The invention provides a metal foil with resin, which has electrical characteristics and mechanical strength, is useful for manufacturing a printed circuit board, has a high-homogeneity resin layer containing a fluorine polymer, and is not easy to warp, and an efficient manufacturing method thereof.

Technical scheme for solving technical problem

The present invention has the following aspects.

[1] A method for producing a resin-bearing metal foil having a resin layer on the surface of the metal foil, wherein a powder dispersion comprising a solvent and a powder of a tetrafluoroethylene polymer having a temperature range of 260 ℃ or lower exhibiting a storage modulus of 0.1 to 5.0MPa and a melting point of more than 260 ℃ is applied to the surface of the metal foil, the metal foil is held at a temperature within the above temperature range, and the tetrafluoroethylene polymer is further fired at a temperature higher than the above temperature range, thereby forming a resin layer comprising the tetrafluoroethylene polymer on the surface of the metal foil.

[2] The production method according to [1], wherein the resin-coated metal foil has a warpage of 7% or less.

[3] The production method according to [1] or [2], wherein the metal foil has a thickness of 2 to 40 μm.

[4] The production method according to any one of [1] to [3], wherein the thickness of the resin layer is 1 to 50 μm.

[5] The production method according to any one of [1] to [4], wherein the metal foil has a thickness of 2 to 20 μm, and the resin layer has a thickness of 1 μm or more and less than 10 μm.

[6] The production method according to any one of [1] to [5], wherein the powder has a volume-based cumulative 50% diameter of 0.05 to 6.0 μm.

[7] The production process according to any one of [1] to [6], wherein the tetrafluoroethylene-based polymer is a polymer comprising a unit based on tetrafluoroethylene and a unit based on at least one monomer selected from the group consisting of perfluoro (alkyl vinyl ether), hexafluoropropylene and fluoroalkyl ethylene.

[8] The production process according to any one of [1] to [7], wherein the tetrafluoroethylene-based polymer has at least one functional group selected from a carbonyl group-containing group, a hydroxyl group, an epoxy group, an amide group, an amino group and an isocyanate group.

[9] The production method according to any one of [1] to [8], wherein the powder dispersion contains a polymer-like polyol.

[10] The production method according to any one of [1] to [9], wherein the time for holding the metal foil in the temperature range is 30 seconds to 5 minutes.

[11] The production method according to any one of [1] to [10], wherein an atmosphere in which the metal foil is held in the temperature range is an atmosphere containing oxygen.

[12] The production process according to any one of [1] to [11], wherein the temperature at which the tetrafluoroethylene-based polymer is fired is more than 320 ℃.

[13] A resin-coated metal foil, wherein a resin layer having a thickness of 1 [ mu ] m or more and less than 10 [ mu ] m is provided on a surface of a metal foil having a thickness of 2 to 20 [ mu ] m, the resin layer contains a polymer having a unit based on tetrafluoroethylene and a unit based on at least one monomer selected from the group consisting of perfluoro (alkyl vinyl ether), hexafluoropropylene and fluoroalkyl ethylene, and the resin-coated metal foil has a warpage of 7% or less.

[14] The resin-coated metal foil according to [13], wherein a warpage rate is 5% or less.

[15] A method for manufacturing a printed circuit board, wherein a metal foil with resin is manufactured by the manufacturing method according to any one of the above [1] to [12], and the metal foil is etched to form a pattern circuit.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a resin-coated metal foil which has electrical characteristics and mechanical strength, is useful for manufacturing a printed circuit board, has a highly homogeneous resin layer containing a fluoropolymer, and is less likely to warp can be efficiently manufactured.

Detailed Description

The following terms have the following meanings.

"D50 of powder" is the volume-based cumulative 50% diameter of the powder as determined by the laser diffraction scattering method. That is, the particle size distribution of the powder was measured by a laser diffraction scattering method, and a cumulative curve was obtained with the total volume of the particles as 100%, and the particle diameter at a point on the cumulative curve where the cumulative volume reached 50%.

"D90 of powder" is the cumulative 90% diameter on a volume basis of the powder as determined by the laser diffraction scattering method. That is, the particle size distribution of the powder was measured by a laser diffraction scattering method, and a cumulative curve was obtained with the total volume of the particles as 100%, and the particle diameter at a point on the cumulative curve where the cumulative volume reached 90%.

"storage modulus of polymer" is a value measured in accordance with ISO 6721-4:1994(JIS K7244-4: 1999).

"melting point of a polymer" means a temperature corresponding to the maximum of a melting peak measured by Differential Scanning Calorimetry (DSC).

The "warpage of resin-coated metal foil" is a value obtained by cutting a 180mm square test piece out of a resin-coated metal foil and measuring the test piece by the measurement method specified in JIS C6471:1995 (corresponding to International Standard IEC 249-1: 1982).

The "dimensional change rate of the metal foil with resin" is a value obtained as described below. The resin-containing metal foil was cut in a 150mm square, and holes were formed at four corners using a 0.3mm corner, and the positions of the holes were measured with a three-dimensional measuring instrument. The metal foil with the resin-coated metal foil was removed by etching and dried at 130 ℃ for 30 minutes. The positions of the holes cut at the four corners were determined by a three-dimensional measuring instrument. The dimensional change rate was calculated from the difference in the positions of the holes before and after etching.

The arithmetic average roughness "Ra" is the arithmetic average roughness measured according to JIS B0601:2013(ISO 4287:1997, Amd.1: 2009). The standard length lr (cutoff value λ c) for obtaining the roughness curve for Ra was set to 0.8 mm.

The "heat-resistant resin" is a polymer compound having a melting point of 280 ℃ or higher, or a polymer compound having a maximum continuous use temperature of 121 ℃ or higher as defined in JIS C4003: 2010(IEC 60085: 2007).

"(meth) acrylate" is a generic term for both acrylates and methacrylates.

The production method of the present invention is a method of applying a specific powder dispersion liquid to the surface of a metal foil, heating and holding the metal foil in a stepwise manner in a specific temperature atmosphere, and forming a resin layer containing a specific tetrafluoroethylene polymer (hereinafter also referred to as "TFE polymer") on the surface of the metal foil. The powder dispersion used is a dispersion in which powder of a TFE-based polymer is dispersed in a particulate form.

The reason why the resin-attached metal foil obtained by the present invention has a resin layer containing a TFE-based polymer (hereinafter also referred to as "F resin layer") having excellent homogeneity and is not easily warped is not clear, but is considered to be as follows.

The TFE polymer in the present invention has a predetermined melting property (having a melting point of more than 260 ℃) and a predetermined elasticity (having a temperature range of 260 ℃ or lower in which a storage modulus of 0.1 to 5.0MPa is exhibited), and a constant elastic state is formed in the above temperature range. When the dispersion liquid containing the powder of the TFE-based polymer is applied to the surface of a metal foil and held at a temperature within the above temperature range, it is considered that the powder is less likely to break due to its elastic adhesiveness, and a close-packed film state is formed. In the present invention, it is considered that, since the TFE-based polymer is fired at a temperature higher than the above temperature range to form the F resin layer after the film is formed, a dense F resin layer having high homogeneity is formed in this state, and as a result, a resin-attached metal foil which is less likely to warp can be obtained.

The resin-coated metal foil in the present invention has an F resin layer on at least one surface of the metal foil. That is, the metal foil with resin may have an F resin layer only on one side of the metal foil, or may have an F resin layer on both sides of the metal foil.

The warpage rate of the resin-attached metal foil is preferably 7% or less, and particularly preferably 5% or less. The lower limit of the warping rate is usually 0%. In this case, the handling property when the metal foil with resin is processed into a printed circuit board and the transmission characteristics of the resulting printed circuit board are excellent.

The dimensional change rate of the resin-attached metal foil is preferably ± 1% or less, and particularly preferably 0.2% or less. In this case, the printed circuit board obtained from the metal foil with resin can be easily multilayered.

Examples of the material of the metal foil in the present invention include copper, copper alloy, stainless steel, nickel alloy (including 42 alloy), aluminum alloy, titanium alloy, and the like.

The metal foil may, for example, be a rolled copper foil or an electrolytic copper foil. A rust-proof layer (oxide film such as chromate film) or a heat-resistant layer may be formed on the surface of the metal foil.

The ten-point average roughness of the surface of the metal foil is preferably 0.2 to 1.5 μm. In this case, the adhesion to the F resin layer is good, and a printed board having excellent transmission characteristics can be easily obtained.

The thickness of the metal foil is not limited as long as it is a thickness that can function in the use of the resin-coated metal foil, and is preferably 2 μm or more, and particularly preferably 3 μm or more. The thickness of the metal foil is preferably 40 μm or less, more preferably 20 μm or less, and particularly preferably 15 μm or less. Specific examples of the thickness of the metal foil include 2 to 40 μm, 2 to 20 μm, and 2 to 15 μm.

The surface of the metal foil may be treated with the silane coupling agent, the entire surface of the metal foil may be treated with the silane coupling agent, or a part of the surface of the metal foil may be treated with the silane coupling agent.

The F resin layer in the present invention is a resin layer containing a TFE-based polymer formed from the powder dispersion of the present invention by the production method of the present invention.

The water contact angle of the surface of the F resin layer is preferably 70 to 100 degrees, and particularly preferably 70 to 90 degrees. When the above range is not more than the upper limit, the adhesion of the F resin layer to another substrate is more excellent. When the above range is not less than the lower limit, the electrical characteristics (low dielectric loss and low dielectric constant) of the F resin layer are more excellent.

The thickness of the F resin layer is preferably 1 μm or more, more preferably 2 μm or more, and particularly preferably 5 μm or more. The thickness of the F resin layer is preferably 50 μm or less, more preferably 15 μm or less, and particularly preferably less than 10 μm. Within this range, the transmission characteristics of the printed circuit board and the suppression of warping of the metal foil with resin are easily balanced. In the case where the resin-coated metal foil has the F resin layers on both surfaces of the metal foil, the composition and thickness of each F resin layer are preferably the same from the viewpoint of suppressing warpage of the resin-coated metal foil.

Specific examples of the thickness of the F resin layer include 1 to 50 μm, 1 to 15 μm, 1 μm or more and less than 10 μm, and 5 to 15 μm.

The preferred embodiment of the thickness of the metal foil and the thickness of the F resin layer in the present invention includes an embodiment in which the former is 2 to 20 μm and the latter is 1 μm or more and less than 10 μm. Since the dense F resin layer having high homogeneity can be formed by the manufacturing method of the present invention as described above, warping can be suppressed even in the resin-attached metal foil having a thin structure as described above.

The F resin layer preferably has a relative dielectric constant of 2.0 to 3.5, more preferably 2.0 to 3.0. In this case, the F resin layer is excellent in both electrical characteristics and adhesiveness, and is suitable for using a metal foil with resin for a printed board or the like which requires a low dielectric constant.

The Ra of the surface of the F resin layer is smaller than the thickness of the F resin layer, and preferably 2.2-8 μm. Within this range, the adhesiveness and workability of the other substrate can be easily balanced.

The powder containing a TFE-based polymer (hereinafter also referred to as "F powder") in the present invention may contain components other than the TFE-based polymer within a range not impairing the effect of the present invention, but it is preferable to use a TFE-based polymer as a main component. The content of the TFE-based polymer in the F powder is preferably 80 mass% or more, and particularly preferably 100 mass%.

D50 of the F powder is preferably 0.05 to 6 μm, more preferably 0.1 to 3.0 μm, and particularly preferably 0.2 to 3.0. mu.m. Within this range, the flowability and dispersibility of the F powder are good, and the electrical characteristics (low dielectric constant, etc.) and heat resistance of the TFE-based polymer in the resin-coated metal foil are most likely to be exhibited.

D90 of the F powder is preferably 8 μm or less, more preferably 6 μm or less, and particularly preferably 5 μm or less. The D90 of the powder is preferably 0.3 μm or more, particularly preferably 0.8 μm or more. Within this range, the F powder is excellent in fluidity and dispersibility, and the electrical characteristics (low dielectric constant and the like) and heat resistance of the F resin layer are most easily exhibited.

The bulk density of the F powder is preferably 0.05g/mL or more, and particularly preferably 0.08 to 0.5 g/mL.

The dense packing bulk density of the F powder is preferably 0.05g/mL or more, and particularly preferably 0.1 to 0.8 g/mL.

The method for producing the F powder is not particularly limited, and the methods described in [0065] to [0069] of International publication No. 2016/017801 can be used. In addition, for the F powder, if there is a desired powder sold on the market, the powder can be used.

The TFE polymer in the present invention has a melting point of more than 260 ℃, preferably 260 to 320 ℃, particularly preferably 275 to 320 ℃, and most preferably 295 to 310 ℃. In this case, the TFE-based polymer is fired while maintaining its adhesiveness based on its elasticity, and a dense F resin layer is more easily formed.

The TFE polymer in the present invention has a storage modulus of 0.1 to 5.0MPa at 260 ℃ or lower. For example, the TFE polymer has a storage modulus at 260 ℃ of 0.1 to 5.0 MPa.

The TFE polymer preferably has a storage modulus of 0.2 to 4.4MPa, particularly preferably 0.5 to 3.0 MPa. The temperature range in which the TFE polymer exhibits the storage modulus is preferably 180 to 260 ℃, particularly preferably 200 to 260 ℃. In this case, the F powder easily and efficiently exhibits adhesiveness due to elasticity in the above temperature range.

The TFE-based polymer is a polymer including a Tetrafluoroethylene (TFE) -based unit (TFE unit). The TFE-based polymer may be a homopolymer of TFE, or a copolymer of TFE and another monomer copolymerizable with TFE (hereinafter, also referred to as a comonomer). The TFE polymer preferably contains 75 to 100 mol% of TFE units and 0 to 25 mol% of comonomer units based on all units contained in the polymer.

Examples of the TFE-based polymer include Polytetrafluoroethylene (PTFE), a copolymer of TFE and ethylene, a copolymer of TFE and propylene, a copolymer of TFE and perfluoro (alkyl vinyl ether) (PAVE) (PFA), a copolymer of TFE and Hexafluoropropylene (HFP), a copolymer of TFE and fluoroalkyl ethylene (FAE), and a copolymer of TFE and chlorotrifluoroethylene (TFE).

As PAVE, CF is mentioned₂＝CFOCF₃、CF₂＝CFOCF₂CF₃、CF₂＝CFOCF₂CF₂CF₃(PPVE)、CF₂＝CFOCF₂CF₂CF₂CF₃、CF₂＝CFO(CF₂)₈F。

As FAE, CH may be mentioned₂＝CH(CF₂)₂F、CH₂＝CH(CF₂)₃F、CH₂＝CH(CF₂)₄F、CH₂＝CF(CF₂)₃H、CH₂＝CF(CF₂)₄H。

As a preferred embodiment of the TFE-based polymer, a polymer including a TFE unit and a unit based on at least 1 monomer selected from PAVE, HFP, and FAE (hereinafter, also referred to as "comonomer unit F") is also cited.

The polymer preferably contains 90 to 99 mol% of TFE units and 1 to 10 mol% of comonomer units F with respect to all units contained in the polymer. The polymer may be composed of only TFE units and comonomer units F, and may contain other units.

As a preferred embodiment of the TFE-based polymer, there can be mentioned a polymer (hereinafter, also referred to as "polymer F1") containing TFE units, which has at least 1 functional group (hereinafter, also referred to as "functional group") selected from a carbonyl-containing group, a hydroxyl group, an epoxy group, an amide group, an amino group and an isocyanate group.

The functional group may be contained in a unit of the TFE-based polymer or may be contained in a terminal group of the main chain of the polymer F1. The latter polymer may be a polymer having a functional group as an end group derived from a polymerization initiator, a chain transfer agent, or the like.

As the polymer F1, a polymer containing a unit having a functional group and a TFE unit is preferable. In this case, the polymer F1 preferably further contains other units, and particularly preferably contains a comonomer unit F.

The functional group is preferably a carbonyl group from the viewpoint of adhesiveness between the F resin layer and the metal foil. Examples of the carbonyl group-containing group include a carbonate group, a carboxyl group, a haloformyl group, an alkoxycarbonyl group, an acid anhydride residue (-C (O) OC (O)), and a fatty acid residue, and a carboxyl group and an acid anhydride residue are preferable.

As the unit having a functional group, a unit based on a monomer having a functional group is preferable, a unit based on a monomer having a carbonyl group, a unit based on a monomer having a hydroxyl group, a unit based on a monomer having an epoxy group, and a unit based on a monomer having an isocyanate group are more preferable, and a unit based on a monomer having a carbonyl group is particularly preferable.

As the monomer having a carbonyl group, a cyclic monomer having an acid anhydride residue, a monomer having a carboxyl group, a vinyl ester and a (meth) acrylic ester are preferable, and a cyclic monomer having an acid anhydride residue is particularly preferable.

As the above cyclic monomer, itaconic anhydride, citraconic anhydride, 5-norbornene-2, 3-dicarboxylic anhydride (alias: nadic anhydride; hereinafter also referred to as "NAH") or maleic anhydride is preferable.

As the polymer F1, a polymer containing a unit having a functional group and a TFE unit, and a PAVE unit or HFP unit is preferable. Specific examples of the polymer F1 include the polymer (X) described in international publication No. 2018/16644.

The proportion of the TFE unit in the polymer F1 in the total units contained in the polymer F1 is preferably 90 to 99 mol%.

The proportion of the PAVE units in the polymer F1 in all units contained in the polymer F1 is preferably 0.5 to 9.97 mol%.

The proportion of the unit having a functional group in the polymer F1 in the total units contained in the polymer F1 is preferably 0.01 to 3 mol%.

The solvent in the present invention is a dispersion medium, is a solvent compound which is liquid at 25 ℃ and inert and does not react with the F powder, has a lower boiling point than components other than the solvent contained in the powder dispersion, and is preferably a solvent compound which can be volatilized and removed by heating or the like.

Examples of the solvent compound include water, alcohols (methanol, ethanol, isopropanol, etc.), nitrogen-containing compounds (N, N-dimethylformamide, N-dimethylacetamide, N-methyl-2-pyrrolidone, etc.), sulfur-containing compounds (dimethyl sulfoxide, etc.), ethers (diethyl ether, dioxane, etc.), esters (ethyl lactate, ethyl acetate, etc.), ketones (methyl ethyl ketone, methyl isopropyl ketone, cyclopentanone, cyclohexanone, etc.), glycol ethers (ethylene glycol monoisopropyl ether, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), and the like. The solvent compounds can be used alone in 1 kind, also can be more than 2 kinds of combination use.

The solvent compound is preferably a solvent that does not evaporate instantaneously, preferably a solvent compound having a boiling point of 80 to 275 ℃, and particularly preferably a solvent compound having a boiling point of 125 to 250 ℃. In this range, the stability of a wet film (film containing a solvent) formed from the powder dispersion applied to the surface of the metal foil is high.

The solvent in the wet film may be removed before the completion of the firing of the TFE polymer. The evaporative dissipation of the solvent from the wet film may occur before reaching the temperature range exhibiting the above-mentioned specific storage modulus, or may occur in a state of being maintained within the temperature range exhibiting the above-mentioned specific storage modulus. In some cases, the reaction may occur during the firing of the TFE polymer. Preferably, the solvent having the boiling point range is used, and at least a part of the solvent in the wet film is vaporized and dissipated while keeping the TFE-based polymer in a temperature range in which the specific storage modulus is exhibited.

As the solvent compound, preferred are organic compounds, more preferred are cyclohexane (boiling point: 81 ℃ C.), 2-propanol (boiling point: 82 ℃ C.), 1-propanol (boiling point: 97 ℃ C.), 1-butanol (boiling point: 117 ℃ C.), 1-methoxy-2-propanol (boiling point: 119 ℃ C.), N-methylpyrrolidone (boiling point: 202 ℃ C.), γ -butyrolactone (boiling point: 204 ℃ C.), cyclohexanone (boiling point: 156 ℃ C.) and cyclopentanone (boiling point: 131 ℃ C.), and particularly preferred are N-methylpyrrolidone, γ -butyrolactone, cyclohexanone and cyclopentanone.

The proportion of the F powder in the powder dispersion is preferably 5 to 60 mass%, particularly preferably 35 to 50 mass%. Within this range, the relative dielectric constant and the dielectric loss tangent of the F resin layer can be easily controlled to low levels. In addition, the powder dispersion has high uniform dispersibility, and the F resin layer has excellent mechanical strength.

The proportion of the solvent in the powder dispersion is preferably 15 to 65% by mass, and particularly preferably 25 to 50% by mass. Within this range, the powder dispersion has excellent coatability and poor appearance of the resin layer is less likely to occur.

The powder dispersion liquid of the present invention may contain other materials within a range not impairing the effects of the present invention. The other materials may or may not be soluble in the powder dispersion.

The powder dispersant preferably contains a dispersant from the viewpoint of improving the dispersion stability of the powder dispersion. As the dispersant, a compound (surfactant) having a hydrophobic portion and a hydrophilic portion is particularly preferable from the viewpoint of imparting adhesiveness to the surface properties of the F resin layer.

When the powder dispersion contains a dispersant, the proportion of the dispersant in the powder dispersion is preferably 0.1 to 30% by mass, and particularly preferably 5 to 10 parts by mass. Within this range, the uniform dispersibility of the F powder is easily balanced with the hydrophilicity and electrical characteristics of the surface of the F resin layer.

The dispersant in the present invention is preferably a polyol, a polyoxyalkylene glycol, polycaprolactam, or a polymer-like polyol, and more preferably a polymer-like polyol.

The polymer-like polyol means a polymer having a unit based on a monomer having a carbon-carbon unsaturated double bond and 2 or more hydroxyl groups. The polymer-like polyol is particularly preferably polyvinyl alcohol, polyvinyl butyral or a fluorinated polyol, and most preferably a fluorinated polyol. However, the fluoropolyol is not a TFE-based polymer, but a polymer having a hydroxyl group and a fluorine atom. In addition, in the fluoropolyol, a part of the hydroxyl groups may be chemically modified.

As the fluoropolyol, a copolymer of a (meth) acrylate having a polyfluoroalkyl group or a polyfluoroalkyl group (hereinafter, also referred to as "(meth) acrylate F") and a (meth) acrylate having a polyoxyalkylene monool group (hereinafter, also referred to as "(meth) acrylate AO") (hereinafter, also referred to as "dispersed polymer F") is particularly preferable.

As (meth) acrylic esters F, preference is given to those of the formula CH₂＝CR¹C(O)O-X¹-R^FThe compound shown in the specification.

R¹Represents a hydrogen atom or a methyl group.

X¹Is represented by- (CH)₂)₂-、-(CH₂)₃-、-(CH₂)₄-、-(CH₂)₂NHC(O)-、-(CH₂)₃NHC (O) -or-CH₂CH(CH₃)NHC(O)。

R^Frepresents-OCF (CF)₃)(C(CF(CF₃)₂)(＝C(CF₃)₂)、-OC(CF₃)(＝C(CF(CF₃)₂)(CF(CF₃)₂)、-OCH(CH₂OCH₂CH₂(CF₂)₄F)₂、-OCH(CH₂OCH₂CH₂(CF₂)₆F)₂、-(CF₂)₄F or- (CF)₂)₆F。

As (meth) acrylate AO, preference is given to using a compound of the formula CH₂＝CR²C(O)O-Q²-OH.

R²Represents a hydrogen atom or a methyl group.

Q²Is represented by- (CH)₂)_m(OCH₂CH₂)_n-、-(CH₂)_m(OCH₂CH(CH₃))_n-or- (CH)₂)_m(OCH₂CH₂CH₂CH₂)_n- (m represents an integer of 1 to 4, n represents an integer of 2 to 100, and n is preferably an integer of 2 to 20).

Specific examples of the (meth) acrylic ester F include

CH₂＝CHCOO(CH₂)₄OCF(CF₃)(C(CF(CF₃)₂)(＝C(CF₃)₂)、

CH₂＝CHCOO(CH₂)₄OC(CF₃)(＝C(CF(CF₃)₂)(CF(CF₃)₂)、

CH₂＝C(CH₃)COO(CH₂)₂NHCOOCH(CH₂OCH₂CH₂(CF₂)₆F)₂、

CH₂＝C(CH₃)COO(CH₂)₂NHCOOCH(CH₂OCH₂CH₂(CF₂)₄F)₂、

CH₂＝C(CH₃)COO(CH₂)₂NHCOOCH(CH₂OCH₂(CF₂)₆F)₂、

CH₂＝C(CH₃)COO(CH₂)₂NHCOOCH(CH₂OCH₂(CF₂)₄F)₂、

CH₂＝C(CH₃)COO(CH₂)₃NHCOOCH(CH₂OCH₂(CF₂)₆F)₂、

CH₂＝C(CH₃)COO(CH₂)₃NHCOOCH(CH₂OCH₂(CF₂)₄F)₂。

Specific examples of the (meth) acrylic acid ester AO include CH₂＝CHCOO(CH₂CH₂O)₈OH、CH₂＝CHCOO(CH₂CH₂O)₁₀OH、CH₂＝CHCOO(CH₂CH₂O)₁₂OH、CH₂＝C(CH₃)COO(CH₂CH(CH₃)O)₈OH、CH₂＝C(CH₃)COO(CH₂CH(CH₃)O)₁₂OH、CH₂＝C(CH₃)COO(CH₂CH(CH₃)O)₁₆OH。

The proportion of units based on the (meth) acrylate F relative to all units contained in the dispersion polymer F is preferably 20 to 60 mol%, particularly preferably 20 to 40 mol%.

The proportion of units based on (meth) acrylate AO relative to all units contained in the dispersion polymer F is preferably 40 to 80 mol%, particularly preferably 60 to 80 mol%.

The dispersion polymer F may be composed of only the unit based on the (meth) acrylate AO and the unit based on the (meth) acrylate AO, or may further contain other units.

The fluorine content of the dispersion polymer F is preferably 10 to 45 mass%, particularly preferably 15 to 40 mass%.

The dispersion polymer F is preferably nonionic.

The mass average molecular weight of the dispersed polymer F is preferably 2000 to 80000, and particularly preferably 6000 to 20000.

The powder dispersion liquid of the present invention may further contain other materials than the above-mentioned dispersing agent. The other material may be a non-curable resin or a curable resin.

Examples of the non-curable resin include a hot-melt resin and a non-melt resin. Examples of the hot-melt resin include thermoplastic polyimide. Examples of the non-fusible resin include cured products of curable resins.

Examples of the curable resin include a polymer having a reactive group, an oligomer having a reactive group, a low-molecular compound, and a low-molecular compound having a reactive group. Examples of the reactive group include a carbonyl group, a hydroxyl group, an amino group, and an epoxy group.

Examples of the curable resin include epoxy resins, thermosetting polyimides, polyamic acids which are precursors of polyimides, thermosetting acrylic resins, phenol resins, thermosetting polyester resins, thermosetting polyolefin resins, thermosetting modified polyphenylene ether resins, polyfunctional cyanate ester resins, polyfunctional maleimide-cyanate ester resins, polyfunctional maleimide resins, vinyl ester resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, and melamine-urea copolymer resins. Among them, from the viewpoint of being usable for printed board applications, thermosetting polyimide, polyimide precursor, epoxy resin, thermosetting acrylic resin, bismaleimide resin, and thermosetting polyphenylene ether resin are preferable as the thermosetting resin, and epoxy resin and thermosetting polyphenylene ether resin are particularly preferable.

Specific examples of the epoxy resin include naphthalene type epoxy resins, cresol novolac type epoxy resins, bisphenol a type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, alicyclic epoxy resins, aliphatic chain epoxy resins, cresol novolac type epoxy resins, phenol novolac type epoxy resins, alkylphenol novolac type epoxy resins, aralkyl type epoxy resins, bisphenol type epoxy resins, dicyclopentadiene type epoxy resins, trishydroxyphenylmethane type epoxy compounds, epoxides of condensates of phenol and aromatic aldehydes having a phenolic hydroxyl group, diglycidyl etherate of bisphenol, diglycidyl etherate of naphthalene diol, glycidyl etherate of phenol, diglycidyl etherate of alcohol, triglycidyl isocyanurate, and the like.

Examples of the bismaleimide resin include a resin composition (BT resin) obtained by using a bisphenol a type cyanate resin and a bismaleimide compound in combination as disclosed in japanese patent laid-open No. 7-70315, and the invention and the background art thereof as disclosed in international publication No. 2013/008667.

The polyamic acid generally has a functional group capable of reacting with the polymer F¹Reactive group (c) reactive with the functional group(s).

Examples of the diamine and polycarboxylic acid dianhydride for forming the polyamic acid include diamines and polycarboxylic acid dianhydrides described in [0020] of Japanese patent No. 5766125, [0019] of Japanese patent No. 5766125, and [0055] and [0057] of Japanese patent laid-open Nos. 2012 and 145676. Among these, polyamic acids obtained by combining aromatic diamines such as 4,4 ' -diaminodiphenyl ether and 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane with aromatic polybasic acid dianhydrides such as pyromellitic dianhydride, 3 ', 4,4 ' -biphenyltetracarboxylic dianhydride and 3,3 ', 4,4 ' -benzophenonetetracarboxylic dianhydride are preferred.

Examples of the hot-melt resin include thermoplastic resins such as thermoplastic polyimides and hot-melt cured products of curable resins.

The thermoplastic resin may, for example, be a polyester resin, a polyolefin resin, a styrene resin, a polycarbonate, a thermoplastic polyimide, a polyarylate, a polysulfone, a polyarylsulfone, an aromatic polyamide, an aromatic polyetheramide, a polyphenylene sulfide, a polyaryl ether ketone, a polyamideimide, a liquid crystalline polyester, a polyphenylene ether or the like, and preferably a thermoplastic polyimide, a liquid crystalline polyester or a polyphenylene ether.

Further, as other materials that may be contained in the powder dispersion liquid in the present invention, there may be mentioned adhesives, thixotropy imparting agents, antifoaming agents, inorganic fillers, reactive alkoxysilanes, dehydrating agents, plasticizers, weather-resistant agents, antioxidants, heat stabilizers, lubricants, antistatic agents, whitening agents, colorants, conductive agents, mold release agents, surface treatment agents, viscosity modifiers, flame retardants, and the like.

If the powder dispersion in the present invention contains a binder, the F powder can be suppressed from falling off (dusting) from the metal foil when the F resin layer is formed. Examples of the binder include a thermoplastic organic binder and a thermosetting organic binder. The binder is preferably a compound that decomposes and volatilizes in a temperature range in which the TFE-based polymer is fired. Examples of the binder include acrylic resin binders, cellulose resin binders, vinyl alcohol resin binders, wax resin binders, and gelatin. The binder may be used alone in 1 kind, or in combination of 2 or more kinds.

In the present invention, the powder dispersion is applied to the surface of the metal foil.

The coating method may be any method as long as a stable wet film formed from a powder dispersion is formed on the surface of the metal foil after coating, and examples thereof include a spray coating method, a roll coating method, a spin coating method, a gravure coating method, a microgravure coating method, a gravure offset coating method, a knife coating method, a kiss roll coating method (japanese: キスコート method), a bar coating method, a die coating method, a jet meyer bar coating method (japanese: ファウンテンメイヤーバー method), and a slit die coating method.

Before the metal foil is supplied to a temperature range where the TFE polymer exhibits a storage modulus of 0.1 to 5.0MPa, the metal foil may be heated at a temperature lower than the above temperature range to adjust the state of the wet film. The adjustment is performed to such an extent that the solvent is not completely volatilized, and is usually performed to such an extent that 50 mass% or less of the solvent is volatilized.

In the present invention, after the powder dispersion is applied to the surface of the metal foil, the metal foil is held at a temperature (hereinafter also referred to as "holding temperature") within a temperature range in which the TFE-based polymer exhibits a storage modulus of 0.1 to 5.0 MPa. The holding temperature represents the temperature of the atmosphere.

The maintenance can be carried out in one step or in more than two steps at different temperatures.

The holding method may be a method using an oven, a method using a forced air drying oven, a method of irradiating heat rays such as infrared rays, or the like.

The atmosphere during the holding may be either normal pressure or reduced pressure. The atmosphere in the above-mentioned holding may be any of an oxidizing gas (oxygen, etc.) atmosphere, a reducing gas (hydrogen, etc.) atmosphere, and an inert gas (helium, neon, argon, nitrogen, etc.) atmosphere.

The atmosphere during holding is preferably an atmosphere containing oxygen from the viewpoint of improving the adhesiveness of the F resin layer.

The oxygen concentration (volume basis) in the atmosphere containing oxygen is preferably 1X 10²～3×10⁵ppm, particularly preferably 0.5X 10³～1×10⁴ppm (wt.%). Within this range, the adhesiveness of the F resin layer and the oxidation inhibition of the metal foil are easily balanced.

The holding temperature is preferably 150 to 260 ℃, particularly preferably 200 to 260 ℃.

The time for holding at the holding temperature is preferably 0.1 to 10 minutes, and particularly preferably 0.5 to 5 minutes.

In the present invention, the TFE-based polymer is further fired at a temperature exceeding the above temperature range (hereinafter also referred to as "firing temperature"), and an F resin layer is formed on the surface of the metal foil. The firing temperature represents the temperature of the atmosphere. In the present invention, since the melt bonding of the TFE-based polymer is performed in a state where the F powder is densely packed, an F resin layer having excellent homogeneity is formed, and the metal foil with resin is less likely to warp. Further, if the powder dispersion contains a hot-melt resin, an F resin layer composed of a mixture of a TFE-based polymer and a hot-melt resin can be formed, and if the powder dispersion contains a hot-melt resin, an F resin layer composed of a cured product of a TFE-based polymer and a hot-melt resin can be formed.

Examples of the heating method include a method using an oven, a method using a forced air drying oven, and a method of irradiating heat rays such as infrared rays. In order to improve the smoothness of the surface of the F resin layer, the pressing may be performed by a hot plate, a hot roller, or the like. As a heating method, a method of irradiating far infrared rays is preferable from the viewpoint that firing can be performed in a short time and the far infrared furnace is relatively compact. The heating method may be a combination of infrared heating and hot air heating.

From the viewpoint of promoting homogeneous fusion bonding of TFE polymers, the effective wavelength band of far infrared rays is preferably 2 to 20 μm, more preferably 3 to 7 μm.

The atmosphere during firing may be either normal pressure or reduced pressure. The atmosphere in the firing may be any of an oxidizing gas (oxygen, etc.) atmosphere, a reducing gas (hydrogen, etc.) atmosphere, and an inert gas (helium, neon, argon, nitrogen, etc.) atmosphere, and is preferably a reducing gas atmosphere or an inert gas atmosphere from the viewpoint of suppressing oxidative deterioration of the metal foil and the F resin layer to be formed, respectively.

The atmosphere during firing is preferably a gas atmosphere containing an inert gas and having a low oxygen concentration, and is preferably a gas atmosphere containing nitrogen and having an oxygen concentration (based on volume) of less than 500 ppm. The oxygen concentration (on a volume basis) is particularly preferably 300ppm or less. The oxygen concentration (volume basis) is usually 1ppm or more.

The firing temperature is preferably over 320 ℃ and particularly preferably 330 to 380 ℃. In this case, the TFE-based polymer can more easily form a dense F resin layer.

The time for holding at the firing temperature is preferably 30 seconds to 5 minutes, and particularly preferably 1 to 2 minutes.

When the resin layer in the resin-attached metal foil is a conventional insulating material (cured product of a thermosetting resin such as polyimide), heating for a long time is required to cure the thermosetting resin. On the other hand, in the present invention, the resin layer can be formed by heating in a short time due to the melt bonding of the TFE-based polymer. In addition, in the case where the powder dispersion contains a thermosetting resin, the firing temperature can be lowered. Accordingly, the manufacturing method of the present invention is a method of reducing a thermal load on a metal foil with a resin when forming a resin layer on the metal foil, and is also a method of reducing damage to the metal foil.

In the metal foil with resin of the present invention, the surface of the F resin layer may be subjected to a surface treatment in order to control the coefficient of linear expansion of the F resin layer or to further improve the adhesiveness of the F resin layer.

Examples of the surface treatment method for the surface of the F resin layer include annealing treatment, corona discharge treatment, atmospheric pressure plasma treatment, vacuum plasma treatment, UV ozone treatment, excimer treatment, chemical etching, silane coupling treatment, and surface micro-roughening treatment.

The temperature in the annealing treatment is preferably 80-190 ℃, and particularly preferably 120-180 ℃.

The pressure in the annealing treatment is preferably 0.001 to 0.030MPa, and particularly preferably 0.005 to 0.015 MPa.

The time for the annealing treatment is preferably 10 to 300 minutes, and particularly preferably 30 to 120 minutes.

Examples of the plasma irradiation device in the plasma processing include a high-frequency induction system, a capacitive coupling electrode system, a corona discharge electrode-plasma spray system, a parallel plate system, a remote plasma system, an atmospheric pressure plasma system, and an ICP high-density plasma system.

The gas used for the plasma treatment may, for example, be oxygen, nitrogen, a rare gas (e.g., argon), hydrogen, or ammonia, and a rare gas or nitrogen is preferred. Specific examples of the gas used for the plasma treatment include argon gas, a mixed gas of hydrogen gas and nitrogen gas, and a mixed gas of hydrogen gas, nitrogen gas, and argon gas.

The atmosphere in the plasma treatment is preferably an atmosphere in which the volume fraction of the rare gas or nitrogen gas is 70 vol% or more, and particularly preferably an atmosphere of 100 vol%. Within this range, the Ra of the surface of the F resin layer can be easily adjusted to 2.0 μm or less, and fine irregularities can be formed on the surface of the F resin layer.

In the resin-coated metal foil obtained in the present invention, the surface of the F resin layer is excellent in homogeneity and is not easily warped, and therefore, the F resin layer can be easily laminated with another substrate.

Examples of the other substrate include a heat-resistant resin film, a prepreg which is a precursor of a fiber-reinforced resin plate, a laminate having a heat-resistant resin film layer, and a laminate having a prepreg layer.

A prepreg is a sheet-like substrate obtained by impregnating a base material (e.g., chopped jute, woven fabric, etc.) of reinforcing fibers (e.g., glass fibers, carbon fibers, etc.) with a thermosetting resin or a thermoplastic resin.

The heat-resistant resin film is a film containing 1 or more kinds of heat-resistant resins, and may be a single-layer film or a multilayer film.

Examples of the heat-resistant resin include polyimide, polyarylate, polysulfone, polyarylsulfone, aromatic polyamide, aromatic polyether amide, polyphenylene sulfide, polyaryletherketone, polyamideimide, and liquid crystal polyester.

As a method for laminating another base material on the surface of the F resin layer of the resin-coated metal foil of the present invention, a method of hot-pressing the resin-coated metal foil and another substrate may be mentioned.

The pressing temperature when the other substrate is a prepreg is preferably not higher than the melting point of the TFE polymer, more preferably 120 to 300 ℃, and particularly preferably 160 to 220 ℃. Within this range, thermal degradation of the prepreg can be suppressed, and the F resin layer and the prepreg can be firmly bonded.

The pressing temperature when the substrate is a heat-resistant resin film is preferably 310 to 400 ℃. Within this range, thermal degradation of the heat-resistant resin film can be suppressed, and the F resin layer and the heat-resistant resin film can be firmly bonded.

The hot pressing is preferably performed in a reduced pressure atmosphere, and particularly preferably in a degree of vacuum of 20kPa or less. Within this range, bubbles can be prevented from entering the interfaces of the F resin layer, the substrate, and the metal foil in the laminate, and the deterioration due to oxidation can be prevented.

In the hot pressing, it is preferable to raise the temperature after the degree of vacuum is reached. If the temperature is raised before the degree of vacuum is reached, the F resin layer is softened, that is, the F resin layer is pressure-bonded in a state having a certain degree of fluidity and adhesiveness, which causes generation of bubbles.

The pressure in the hot pressing is preferably 0.2MPa or more. The upper limit of the pressure is preferably 10MPa or less. Within this range, breakage of the substrate can be suppressed, and the F resin layer and the substrate can be firmly bonded.

The resin-coated metal foil and laminate of the present invention can be used for the production of printed boards as flexible copper-clad laminates or rigid copper-clad laminates.

For example, if a method of processing a metal foil with a resin of the present invention into a conductor circuit (pattern circuit) of a predetermined pattern by etching or the like, or a method of processing a metal foil with a resin of the present invention into a pattern circuit by an electroplating method (a semi-additive method (SAP method), a modified semi-additive method (MSAP method), or the like) is used, a printed board can be manufactured from the metal foil with a resin of the present invention.

In the production of the printed circuit board, after the pattern circuit is formed, an interlayer insulating film may be formed on the pattern circuit, and the pattern circuit may be further formed on the interlayer insulating film. The interlayer insulating film can be formed, for example, from the powder dispersion of the present invention.

In the production of the printed circuit board, a solder resist may be laminated on the pattern circuit. The solder resist may be formed, for example, from the powder dispersion of the present invention.

In the production of a printed circuit board, a cover lay film may be laminated on a pattern circuit. The coating film can be formed, for example, from the powder dispersion of the present invention.

Examples

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

The following shows various measurement methods.

< melting Point of Polymer >

The temperature of the TFE polymer was raised at a rate of 10 ℃ per minute by using a differential scanning calorimeter (DSC-7020, manufactured by Seiko Seisaku-Sho Ltd. (セイコーインスツル Co., Ltd.)) to measure the temperature.

< storage modulus of Polymer >

The storage modulus at 260 ℃ was measured by raising the temperature from 20 ℃ at a rate of 2 ℃/min under the conditions of a frequency of 10Hz, a static force of 0.98N and a dynamic displacement of 0.035% using a dynamic viscoelasticity measuring apparatus (DMS6100, SII Nano science and technology Co., Ltd., SII ナノテクノロジー) in accordance with ISO 6721-4:1994(JIS K7244-4: 1999).

< D50 and D90 of powder >

The powder was dispersed in water and measured using a laser diffraction scattering particle size distribution measuring device (horiba, japan), LA-920 measuring device.

< homogeneity of resin layer >

The resin layer was visually observed from obliquely above under light irradiation, and evaluated according to the following criteria.

O: no pattern was confirmed.

And (delta): the shaddock peel-like pattern was confirmed.

X: a shaddock peel-like pattern was observed, and resin falling was observed mainly at the end portions.

< warpage ratio of resin-containing metal foil >

A180 mm square test piece was cut out of the resin-coated metal foil, and the test piece was measured according to the measuring method specified in JIS C6471: 1995.

O: the resin-coated metal foil has a warpage of 5% or less.

And (delta): the warpage rate of the resin-attached metal foil is greater than 5% and not more than 7%.

X: the warpage rate of the resin-attached metal foil is more than 7%.

[ TFE polymers ]

Polymer 1: a polymer having a melting point of 300 ℃ and a storage modulus at 260 ℃ of 1.1MPa, which is a copolymer comprising TFE-based units, NAH-based units, and PPVE-based units in that order of 97.9 mol%, 0.1 mol%, 2.0 mol%.

Polymer 2: a polymer having a melting point of 310 ℃ and a storage modulus at 260 ℃ of 4.8MPa, which is a copolymer comprising TFE-based units and PPVE-based units in that order, 98 mol%, 2 mol%.

Polymer 3: a polymer having a melting point of 265 ℃ and a storage modulus at 260 ℃ of 0.5MPa, which is a copolymer comprising TFE-based units and HFP-based units in this order of 82 mol%, 18 mol%.

Polymer 4: a polymer having a melting point greater than 320 ℃ and a storage modulus at 260 ℃ greater than 5.0MPa, which is a polymer comprising 99.5 mol% or more of TFE-based units.

[ dispersing agent ]

Dispersant 1: copolymers of acrylates having a perfluoroalkenyl group and acrylates having a polyoxyethylene group and an alcoholic hydroxyl group (nonionic surfactants).

[ Metal foil ]

Copper foil 1: a low-grained copper foil having a thickness of 12 μm (ten-point average roughness of the surface of 0.6 μm).

[ powder ]

Powder 1: powder of Polymer 1 having a D50 of 1.7 μm and a D90 of 3.8 μm (loose bulk density of 0.269g/mL and dense bulk density of 0.315 g/mL).

Powder 2: a powder of Polymer 2 having a D50 value of 2.4 μm and a D90 value of 5.5. mu.m.

Powder 3: a powder of Polymer 3 having a D50 value of 3.1 μm and a D90 value of 5.9. mu.m.

Powder 4: a powder of Polymer 4 having a D50 value of 0.3 μm and a D90 value of 0.6. mu.m.

[ example 1]

50 parts by mass of powder 1, 5 parts by mass of dispersant 1, and 45 parts by mass of N-methylpyrrolidone were mixed to prepare dispersion 1.

The dispersion 1 was applied on the surface of the copper foil 1 using a die coater, and the copper foil 1 was passed through a through-air drying furnace (atmosphere temperature: 260 ℃, atmosphere gas: nitrogen gas having an oxygen concentration of 8000 ppm) and held for 1 minute, and further passed through a far-infrared furnace (temperature: 340 ℃, gas: nitrogen gas having an oxygen concentration of less than 100 ppm) and held for 1 minute, to obtain a resin-bearing copper foil having a resin layer (thickness of 5 μm) of the polymer 1 on the surface of the copper foil 1. The evaluation results of the homogeneity of the resin layer and the warpage rate of the metal foil with resin are shown in table 1 below.

[ examples 2 to 5]

Resin-coated copper foils were obtained in the same manner as in example 1, except that the powder and the atmospheric temperature of the through-air drying oven were changed, and the respective evaluations were performed. The results are summarized in Table 1 below.

[ Table 1]

Possibility of industrial utilization

The production method of the present invention is suitable for producing a resin-coated metal foil which has a highly homogeneous resin layer containing a fluoropolymer and is less likely to warp, and is useful for producing a printed circuit board or the like.

The entire contents of the specification, claims and abstract of japanese patent application No. 2018-104010 filed on 30/5/2018 are cited as the disclosure of the specification of the present invention.

Claims (15)

1. A method for producing a resin-bearing metal foil having a resin layer on the surface of the metal foil, wherein a powder dispersion containing a powder of a tetrafluoroethylene polymer having a temperature range of 260 ℃ or lower exhibiting a storage modulus of 0.1 to 5.0MPa and a melting point of more than 260 ℃ and a solvent is applied to the surface of the metal foil, the metal foil is held at a temperature within the temperature range, and the tetrafluoroethylene polymer is further fired at a temperature higher than the temperature range, thereby forming a resin layer containing the tetrafluoroethylene polymer on the surface of the metal foil.

2. The manufacturing method according to claim 1, wherein the warping rate of the metal foil with resin is 7% or less.

3. The method of claim 1 or 2, wherein the metal foil has a thickness of 2 to 40 μm.

4. The method according to any one of claims 1 to 3, wherein the thickness of the resin layer is 1 to 50 μm.

5. The method according to any one of claims 1 to 4, wherein the metal foil has a thickness of 2 to 20 μm, and the resin layer has a thickness of 1 μm or more and less than 10 μm.

6. The production method according to any one of claims 1 to 5, wherein the powder has a volume-based cumulative 50% diameter of 0.05 to 6.0 μm.

7. The production process according to any one of claims 1 to 6, wherein the tetrafluoroethylene-based polymer is a polymer comprising units based on tetrafluoroethylene and units based on at least one monomer selected from the group consisting of perfluoro (alkyl vinyl ether), hexafluoropropylene and fluoroalkyl ethylene.

8. The production method according to any one of claims 1 to 7, wherein the tetrafluoroethylene-based polymer has at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxyl group, an epoxy group, an amide group, an amino group and an isocyanate group.

9. The production method according to any one of claims 1 to 8, wherein the powder dispersion liquid contains a polymer-like polyol.

10. The production method according to any one of claims 1 to 9, wherein the time for holding the metal foil in the temperature range is 30 seconds to 5 minutes.

11. The production method according to any one of claims 1 to 10, wherein an atmosphere in which the metal foil is maintained in the temperature range is an atmosphere containing oxygen.

12. The process according to any one of claims 1 to 11, wherein the temperature at the time of firing the tetrafluoroethylene-based polymer is more than 320 ℃.

13. A resin-coated metal foil, wherein a resin layer having a thickness of 1 [ mu ] m or more and less than 10 [ mu ] m is provided on a surface of a metal foil having a thickness of 2 to 20 [ mu ] m, the resin layer contains a polymer having a unit based on tetrafluoroethylene and a unit based on at least one monomer selected from the group consisting of perfluoro (alkyl vinyl ether), hexafluoropropylene and fluoroalkyl ethylene, and the resin-coated metal foil has a warpage of 7% or less.

14. The resin-coated metal foil as claimed in claim 13, wherein the warpage rate is 5% or less.

15. A method for manufacturing a printed circuit board, wherein a metal foil with a resin is manufactured by the manufacturing method according to any one of claims 1 to 12, and the metal foil is etched to form a pattern circuit.