CN112203844B

CN112203844B - Method for producing resin-coated metal foil and resin-coated metal foil

Info

Publication number: CN112203844B
Application number: CN201980035404.5A
Authority: CN
Inventors: 山边敦美; 细田朋也; 寺田达也; 笠井涉
Original assignee: Asahi Glass Co Ltd
Current assignee: AGC Inc
Priority date: 2018-05-30
Filing date: 2019-05-23
Publication date: 2023-07-28
Anticipated expiration: 2039-05-23
Also published as: KR20210016327A; TWI820138B; JPWO2019230568A1; JP7167983B2; CN112203844A; TW202003234A; WO2019230568A1; KR102715823B1

Abstract

The present invention provides a method for efficiently producing a resin-coated metal foil having electrical characteristics and mechanical strength, useful for producing a printed board, having a resin layer containing a fluoropolymer and having high homogeneity and being less likely to warp, and the resin-coated metal foil. The method for producing a resin-coated metal foil is a method for producing a resin-coated metal foil having a resin layer on the surface of the metal foil, wherein a powder dispersion comprising a tetrafluoroethylene polymer powder and a solvent is applied to the surface of the metal foil, the tetrafluoroethylene polymer has a temperature range exhibiting a storage modulus of 0.1 to 5.0MPa at 260 ℃ or less and a melting point of more than 260 ℃, the metal foil is held at a temperature within the temperature range, and the tetrafluoroethylene polymer is further baked at a temperature of more than the temperature range, whereby a resin layer comprising the tetrafluoroethylene polymer is formed on the surface of the metal foil.

Description

Method for producing resin-coated metal foil and resin-coated metal foil

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-coated metal foil having an insulating resin layer on the surface of the metal foil is used as a printed board by etching the metal foil.

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

As a material for forming a resin-coated metal foil having a resin layer containing a fluoropolymer, a powder dispersion 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: if other insulating resins and varnishes thereof are blended, various physical properties of the resulting resin-coated metal foil can be arbitrarily adjusted. In addition, the powder dispersion has the following advantages: the resin-coated metal foil can be formed by simply coating the surface of the metal foil and drying the metal foil.

Prior art literature

Patent literature

Patent document 1: international publication No. 2017/222027

Patent document 2: international publication No. 2016/15972

Disclosure of Invention

Technical problem to be solved by the invention

As a manufacturing form of the printed circuit board, the following forms are available: a step of laminating another substrate (prepreg or the like) on the surface of a resin layer (insulating resin layer) containing a fluoropolymer, and forming a multilayered metal foil with a resin; and a mode in which other substrates (coating films and the like) are laminated on the surface of the resin layer and packaged. In this case, from the viewpoints of the electrical characteristics and productivity of the printed board, it is necessary to laminate the resin layer and the other board without warping the resin-coated metal foil.

A method of supplying a resin-coated metal foil having a fluoropolymer-containing resin layer to a 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 that a resin-coated metal foil be supplied to a surface treatment. In addition, the surface treatment may induce a change in shape or a modification of the resin layer with time, and the homogeneity of the resin layer may be impaired.

The present inventors have conducted intensive studies in order to produce a resin-coated metal foil having a high homogeneity resin layer containing a fluoropolymer and being less likely to warp from a powder dispersion containing a fluoropolymer powder. As a result, it has been found that the above-described 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 present invention provides a resin-coated metal foil which has electrical characteristics and mechanical strength, is useful for producing a printed circuit board, has a resin layer containing a fluoropolymer and has high homogeneity, and is not liable to warp, and a method for producing the same with high efficiency.

Technical proposal adopted for solving the technical problems

The present invention has the following configurations.

[1] A process for producing a resin-coated metal foil, which comprises applying a powder dispersion comprising a tetrafluoroethylene polymer powder and a solvent to the surface of a metal foil, wherein the tetrafluoroethylene polymer has a temperature range showing a storage modulus of 0.1 to 5.0MPa at 260 ℃ or less and a melting point of more than 260 ℃, and wherein the metal foil is kept at a temperature within the temperature range, and further wherein the tetrafluoroethylene polymer is fired at a temperature of more than the temperature range to form a resin layer comprising the tetrafluoroethylene polymer on the surface of the metal foil.

[2] The method of producing [1], wherein the warp curvature of the resin-coated metal foil is 7% or less.

[3] The production method as described in [1] or [2], wherein the thickness of the metal foil is 2 to 40. Mu.m.

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

[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 cumulative 50% diameter of the powder on a volume basis is 0.05 to 6.0. Mu.m.

[7] The production method according to any one of [1] to [6], wherein the tetrafluoroethylene 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 method according to any one of [1] to [7], wherein the tetrafluoroethylene 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 [1] to [8], wherein the powder dispersion liquid contains a polymer polyol.

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

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

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

[13] A metal foil with resin, wherein a resin layer having a thickness of 1 μm or more and less than 10 μm is provided on a surface of the metal foil having a thickness of 2 to 20 μm, the resin layer comprises a polymer having a unit based on tetrafluoroethylene and a unit based on at least one monomer selected from perfluoro (alkyl vinyl ether), hexafluoropropylene and fluoroalkyl ethylene, and a warp curvature of the metal foil with resin is 7% or less.

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

[15] A method for producing a printed circuit board, wherein a metal foil with a resin is produced by the production 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 having electrical characteristics and mechanical strength, useful for producing a printed board, having a resin layer containing a fluoropolymer and having high homogeneity and being less likely to warp can be efficiently produced.

Detailed Description

The following terms have the following meanings.

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

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

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

The "melting point of a polymer" refers to a temperature corresponding to the maximum value of a melting peak measured by a Differential Scanning Calorimeter (DSC) method.

The "warp rate of the resin-coated metal foil" is a value obtained by cutting a 180mm square test piece from the resin-coated metal foil and measuring the test piece according to a measuring method prescribed 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-coated metal foil was cut into 150mm square pieces, and the four corners were perforated with 0.3mm turners, and the positions of the holes were measured by a three-dimensional measuring instrument. The metal foil with the resin metal foil was removed by etching and dried at 130 ℃ for 30 minutes. The positions of holes bored at four corners were measured with 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 an arithmetic average roughness measured in accordance with JIS B0601:2013 (ISO 4287:1997, amd.1:2009). The reference length lr (cutoff value λc) for determining the roughness curve at the time of Ra was set to 0.8mm.

The "heat-resistant resin" refers to 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, which is specified in JIS C4003:2010 (IEC 60085:2007).

"(meth) acrylate" is a generic term for acrylate and methacrylate.

The production method of the present invention is a method of applying a specific powder dispersion to the surface of a metal foil, heating and holding the metal foil in a stepwise manner under 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 a powder of the TFE-based polymer is dispersed in a particulate form.

The reason why the resin-coated metal foil obtained by the present invention has a resin layer (hereinafter also referred to as "F resin layer") containing a TFE-based polymer, which is excellent in homogeneity, and is not likely to warp is considered to be the following although it is not clear.

The TFE-based polymer of the present invention has a predetermined meltability (having a melting point of more than 260 ℃) and a predetermined elasticity (having a temperature range of 0.1 to 5.0MPa storage modulus at 260 ℃ or less), and forms a certain elastic state in the above temperature range. When the dispersion of the powder containing the TFE-based polymer is applied to the surface of the metal foil and held at a temperature within the above temperature range, it is considered that the powder is less likely to be broken due to adhesion resulting from elasticity, and a close-packed film state is formed. In the present invention, since the F resin layer is formed by firing the TFE polymer under the condition that the temperature is higher than the above temperature range after the film state is formed, the F resin layer is formed in this state with high uniformity and compactness, and as a result, a resin-coated metal foil with less warpage can be obtained.

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

The warpage of the resin-coated metal foil is preferably 7% or less, and particularly preferably 5% or less. The lower limit of the warp curvature is typically 0%. In this case, the workability in processing the resin-coated metal foil into a printed board and the transfer characteristics of the obtained printed board are excellent.

The dimensional change rate of the resin-coated metal foil is preferably ±1% or less, and particularly preferably 0.2% or less. In this case, it is easy to multilayer a printed board obtained from a resin-coated metal foil.

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.

Examples of the metal foil include a rolled copper foil and an electrolytic copper foil. An antirust layer (e.g., an oxide film such as chromate) and 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 excellent in transfer characteristics can be easily obtained.

The thickness of the metal foil may be any 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. Mu.m, 2 to 20. Mu.m, and 2 to 15. Mu.m.

The surface of the metal foil may be treated with a silane coupling agent, the entire surface of the metal foil may be treated with a silane coupling agent, or a part of the surface of the metal foil may be treated with a 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 according to the production method of the present invention.

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

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. Further, 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, it is easy to balance the transfer characteristics of the printed board with the suppression of warpage of the resin-coated metal foil. In the case where the resin-coated metal foil has F resin layers on both sides 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. Mu.m, 1 to 15. Mu.m, 1 μm or more and less than 10. Mu.m, 5 to 15. Mu.m, and the like.

The preferable form of the thickness of the metal foil and the thickness of the F resin layer in the present invention is, for example, a form in which the former is 2 to 20. Mu.m, and the latter is 1 μm or more and less than 10. Mu.m. By the production method of the present invention, since the F resin layer having high uniformity and high density can be formed as described above, warpage can be suppressed even in the resin-coated metal foil having the above-described thin structure.

The relative dielectric constant of the F resin layer is preferably 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 adhesion, and is suitable for use in a printed board or the like requiring a low dielectric constant.

The Ra of the surface of the F resin layer is smaller than the thickness of the F resin layer, preferably 2.2 to 8. Mu.m. Within this range, the adhesion and workability of other substrates are 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 that does not impair the effects of the present invention, but preferably contains the 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%.

The D50 of the F powder is preferably 0.05 to 6. Mu.m, more preferably 0.1 to 3.0. Mu.m, particularly preferably 0.2 to 3.0. Mu.m. Within this range, the F powder has good fluidity and dispersibility, and the TFE polymer in the resin-coated metal foil most easily exhibits electrical characteristics (low dielectric constant, etc.) and heat resistance.

The D90 of the F powder is preferably 8 μm or less, more preferably 6 μm or less, 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 has good fluidity and dispersibility, and the F resin layer most easily exhibits electrical characteristics (low dielectric constant, etc.) and heat resistance.

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

The dense packing bulk density of the F powder is preferably 0.05g/mL or more, particularly preferably 0.1 to 0.8g/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 on the market, the powder can be used.

The TFE-based 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 adhesion due to its elasticity, and a dense F resin layer is more easily formed.

The TFE-based polymer in the present invention has a temperature range showing a storage modulus of 0.1 to 5.0MPa at 260 ℃. For example, TFE polymers have storage moduli of 0.1 to 5.0MPa at 260 ℃.

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

The TFE-based polymer is a polymer containing Tetrafluoroethylene (TFE) -based units (TFE units). 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-based polymer preferably contains 75 to 100 mol% of TFE units and 0 to 25 mol% of comonomer-based units, relative to 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.

As PAVE, CF can be mentioned ₂ ＝CFOCF ₃ 、CF ₂ ＝CFOCF ₂ CF ₃ 、CF ₂ ＝CFOCF ₂ CF ₂ CF ₃ (PPVE)、CF ₂ ＝CFOCF ₂ CF ₂ CF ₂ CF ₃ 、CF ₂ ＝CFO(CF ₂ ) ₈ F。

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

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

The polymer preferably contains 90 to 99 mol% of TFE units and 1 to 10 mol% of comonomer units F, relative 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.

The TFE-based polymer may be 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 carbonyl group-containing, hydroxyl group-containing, epoxy group-containing, amide group-containing, amino group-containing and isocyanate group-containing.

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 a terminal 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 another unit, and particularly preferably contains a comonomer unit F.

The functional group is preferably a carbonyl group from the viewpoint of adhesion between the F resin layer and the metal foil. Examples of the carbonyl 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 preferably a carboxyl group and an acid anhydride residue.

The functional group-containing unit is preferably a unit based on a functional group-containing monomer, more preferably a unit based on a carbonyl group-containing monomer, a unit based on a hydroxyl group-containing monomer, a unit based on an epoxy group-containing monomer, and a unit based on an isocyanate group-containing monomer, and particularly preferably a unit based on a carbonyl group-containing monomer.

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) acrylate are preferable, and a cyclic monomer having an acid anhydride residue is particularly preferable.

As the cyclic monomer, itaconic anhydride, citraconic anhydride, 5-norbornene-2, 3-dicarboxylic anhydride (also referred to as "NAH" hereinafter) 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 an HFP unit is preferable. Specific examples of the polymer F1 include a polymer (X) described in International publication No. 2018/16644.

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

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

The proportion of the functional group-containing units in the polymer F1 is preferably 0.01 to 3 mol% based on the total units contained in the polymer F1.

The solvent in the present invention is a dispersion medium, and is a solvent compound which is inert to the liquid at 25 ℃ and does not react with the F powder, and has a boiling point lower than that of a component 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.), cellosolve (methyl cellosolve, ethyl cellosolve, etc.), and the like. The solvent compound may be used alone or in combination of 1 or more than 2.

The solvent compound is preferably a solvent which does not instantaneously volatilize, 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 wet film (film containing a solvent) formed from the powder dispersion liquid applied to the surface of the metal foil has high stability.

The solvent in the wet film may be removed before the firing of the TFE-based polymer is completed. The vaporization dissipation of the solvent from the wet film may occur before reaching the temperature range exhibiting the above-described specific storage modulus, or may occur while being maintained within the temperature range exhibiting the above-described specific storage modulus. In some cases, the firing of the TFE-based polymer may occur. Preferably, a solvent having a boiling point in the above 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 within a temperature range showing the above specific storage modulus.

As the solvent compound, an organic compound is preferable, 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.), gamma-butyrolactone (boiling point: 204 ℃ C.), cyclohexanone (boiling point: 156 ℃ C.), and cyclopentanone (boiling point: 131 ℃ C.), and N-methylpyrrolidone, gamma-butyrolactone, cyclohexanone, and cyclopentanone are particularly preferable.

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 dielectric loss tangent of the F resin layer can be easily controlled to low levels. In addition, the powder dispersion had high uniform dispersibility, and the F resin layer had excellent mechanical strength.

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

The powder dispersion liquid in the present invention may contain other materials within a range that does not impair the effects of the present invention. Other materials may or may not be dissolved in the powder dispersion.

The powder dispersing agent preferably contains a dispersing agent from the viewpoint of improving the dispersion stability of the powder dispersion liquid. As the dispersant, a compound (surfactant) having a hydrophobic site and a hydrophilic site is particularly preferable from the viewpoint of imparting adhesiveness to the surface property 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 mass%, particularly preferably 5 to 10 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, a polycaprolactam, or a polymer polyol, and more preferably a polymer polyol.

The polymer 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 polyol is particularly preferably polyvinyl alcohol, polyvinyl butyral, or a fluorinated polyol, and most preferably a fluorinated polyol. However, the fluorinated polyol is not a TFE-based polymer, but a polymer having hydroxyl groups and fluorine atoms. In addition, in the fluorinated polyol, a part of the hydroxyl groups may be chemically modified.

The fluorinated polyol is particularly preferably a copolymer of a (meth) acrylate having a polyfluoroalkyl group or a polyfluoroalkenyl group (hereinafter, also referred to as a "(meth) acrylate F") and a (meth) acrylate having a polyoxyalkylene monol group (hereinafter, also referred to as a "(meth) acrylate AO") (hereinafter, also referred to as a "dispersion polymer F").

As (meth) acrylic esters F, preference is given to those of the formula CH ₂ ＝CR ¹ C(O)O-X ¹ -R ^F A compound represented by the formula (I).

R ¹ Represents a hydrogen atom or a methyl group.

X ¹ Represents- (CH) ₂ ) ₂ -、-(CH ₂ ) ₃ -、-(CH ₂ ) ₄ -、-(CH ₂ ) ₂ NHC(O)-、-(CH ₂ ) ₃ NHC (O) -or-CH ₂ CH(CH ₃ )NHC(O)。

R ^F representation-OCF (CF) ₃ )(C(CF(CF ₃ ) ₂ )(＝C(CF ₃ ) ₂ )、-OC(CF ₃ )(＝C(CF(CF ₃ ) ₂ )(CF(CF ₃ ) ₂ )、-OCH(CH ₂ OCH ₂ CH ₂ (CF ₂ ) ₄ F) ₂ 、-OCH(CH ₂ OCH ₂ CH ₂ (CF ₂ ) ₆ F) ₂ 、-(CF ₂ ) ₄ F or- (CF) ₂ ) ₆ F。

As the (meth) acrylic acid ester AO, it is preferable to use one represented by the formula CH ₂ ＝CR ² C(O)O-Q ² -OH.

R ² Represents a hydrogen atom or a methyl group.

Q ² Represents- (CH) ₂ ) _m (OCH ₂ CH ₂ ) _n -、-(CH ₂ ) _m (OCH ₂ CH(CH ₃ )) _n -or- (CH) ₂ ) _m (OCH ₂ CH ₂ CH ₂ CH ₂ ) _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 acid ester F include

CH ₂ ＝CHCOO(CH ₂ ) ₄ OCF(CF ₃ )(C(CF(CF ₃ ) ₂ )(＝C(CF ₃ ) ₂ )、

CH ₂ ＝CHCOO(CH ₂ ) ₄ OC(CF ₃ )(＝C(CF(CF ₃ ) ₂ )(CF(CF ₃ ) ₂ )、

CH ₂ ＝C(CH ₃ )COO(CH ₂ ) ₂ NHCOOCH(CH ₂ OCH ₂ CH ₂ (CF ₂ ) ₆ F) ₂ 、

CH ₂ ＝C(CH ₃ )COO(CH ₂ ) ₂ NHCOOCH(CH ₂ OCH ₂ CH ₂ (CF ₂ ) ₄ F) ₂ 、

CH ₂ ＝C(CH ₃ )COO(CH ₂ ) ₂ NHCOOCH(CH ₂ OCH ₂ (CF ₂ ) ₆ F) ₂ 、

CH ₂ ＝C(CH ₃ )COO(CH ₂ ) ₂ NHCOOCH(CH ₂ OCH ₂ (CF ₂ ) ₄ F) ₂ 、

CH ₂ ＝C(CH ₃ )COO(CH ₂ ) ₃ NHCOOCH(CH ₂ OCH ₂ (CF ₂ ) ₆ F) ₂ 、

CH ₂ ＝C(CH ₃ )COO(CH ₂ ) ₃ NHCOOCH(CH ₂ OCH ₂ (CF ₂ ) ₄ F) ₂ 。

Specific examples of the (meth) acrylic acid ester AO include CH ₂ ＝CHCOO(CH ₂ CH ₂ O) ₈ OH、CH ₂ ＝CHCOO(CH ₂ CH ₂ O) ₁₀ OH、CH ₂ ＝CHCOO(CH ₂ CH ₂ O) ₁₂ OH、CH ₂ ＝C(CH ₃ )COO(CH ₂ CH(CH ₃ )O) ₈ OH、CH ₂ ＝C(CH ₃ )COO(CH ₂ CH(CH ₃ )O) ₁₂ OH、CH ₂ ＝C(CH ₃ )COO(CH ₂ CH(CH ₃ )O) ₁₆ OH。

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

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

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

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

The dispersion polymer F is preferably nonionic.

The mass average molecular weight of the dispersion polymer F is preferably 2000 to 80000, 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-melt resin include a cured product of a curable resin.

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

Specific examples of the epoxy resin include naphthalene type epoxy resin, cresol novolak type epoxy resin, bisphenol a type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, cresol novolak type epoxy resin, phenol novolak type epoxy resin, alkylphenol novolak type epoxy resin, aralkyl type epoxy resin, bisphenol type epoxy resin, dicyclopentadiene type epoxy resin, trihydroxyphenyl methane type epoxy compound, epoxide of condensate of phenol and aromatic aldehyde having a phenolic hydroxyl group, diglycidyl ether of bisphenol, diglycidyl ether of naphthalene diol, diglycidyl ether of phenol, diglycidyl ether 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 described in japanese unexamined patent publication No. 7-70315, an invention as described in international publication No. 2013/008667, and a resin as described in the background art thereof.

The polyamic acid generally has a molecular weight that is compatible with polymer F ¹ Reactive groups that react with functional groups of (a) a polymer.

Examples of the diamine and polycarboxylic acid dianhydride that form the polyamic acid include diamines and polycarboxylic acid dianhydrides described in, for example, japanese patent application publication No. 5766125 [0020], japanese patent application publication No. 5766125 [0019], japanese patent application publication nos. 2012-145676 [0055] and [0057 ]. Among them, polyamic acid obtained by combining an aromatic diamine such as 4,4' -diaminodiphenyl ether or 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane with an aromatic polybasic acid dianhydride such as pyromellitic dianhydride, 3', 4' -biphenyl tetracarboxylic dianhydride, or 3,3', 4' -benzophenone tetracarboxylic dianhydride is preferable.

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

Examples of the thermoplastic resin include polyester resins, polyolefin resins, styrene resins, polycarbonates, thermoplastic polyimides, polyarylates, polysulfones, polyarylsulfones, aromatic polyamides, aromatic polyether amides, polyphenylene sulfides, polyaryletherketones, polyamideimides, liquid crystalline polyesters, and polyphenylene oxides, and thermoplastic polyimides, liquid crystalline polyesters, and polyphenylene oxides are preferable.

Examples of the other materials that may be contained in the powder dispersion liquid in the present invention include binders, thixotropic agents, antifoaming agents, inorganic fillers, reactive alkoxysilanes, dehydrating agents, plasticizers, weather-resistant agents, antioxidants, heat stabilizers, lubricants, antistatic agents, brighteners, colorants, conductive agents, release agents, surface treatment agents, viscosity modifiers, flame retardants, and the like.

If the powder dispersion in the present invention contains a binder, it is possible to suppress the F powder from falling off (powder falling) from the metal foil at the time of forming the F resin layer. Examples of the binder include thermoplastic organic binders and thermosetting organic binders. As the binder, a compound which decomposes and volatilizes in a temperature range at which the TFE-based polymer is fired is preferable. Examples of the binder include an acrylic resin binder, a cellulose resin binder, a vinyl alcohol resin binder, a wax resin binder, and gelatin. The binder may be used alone or in combination of 1 or more than 2.

In the present invention, the powder dispersion is coated on 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 coated metal foil, and examples thereof include spray coating, roll coating, spin coating, gravure coating, micro gravure coating, gravure offset coating, doctor blade coating, kiss roll coating (japanese: in the state コ), bar coating, die coating, jet meyer wire bar coating (japanese: in the state of feun), slot die coating, and the like.

The wet film may be adjusted by heating the metal foil at a temperature lower than the above temperature range before the metal foil is fed to the temperature range where the TFE-based polymer exhibits a storage modulus of 0.1 to 5.0 MPa. The adjustment is performed at a level where the solvent does not completely volatilize, and is usually performed at a level where 50 mass% or less of the solvent volatilizes.

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

Examples of the method for holding include a method using an oven, a method using a ventilating and drying oven, and a method of radiating heat rays such as infrared rays.

The atmosphere at the time of holding may be either a normal pressure or a reduced pressure. The atmosphere to be maintained 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.

As the atmosphere during the holding, an atmosphere containing oxygen is preferable from the viewpoint of improving the adhesiveness of the F resin layer.

The oxygen concentration (volume basis) in the oxygen-containing atmosphere is preferably 1X 10 ² ～3×10 ⁵ ppm, particularly preferably 0.5X10 ³ ～1×10 ⁴ ppm. 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℃and particularly preferably 200 to 260 ℃.

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

In the present invention, the TFE polymer is further baked at a temperature exceeding the above temperature range (hereinafter also referred to as "baking temperature"), thereby forming an F resin layer 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 excellent in homogeneity is formed, and the resin-coated metal foil is less likely to warp. Further, if the powder dispersion contains a heat-fusible resin, an F resin layer composed of a mixture of a TFE-based polymer and a fusible resin can be formed, and if the powder dispersion contains a thermosetting resin, an F resin layer composed of a cured product of a TFE-based polymer and a thermosetting resin can be formed.

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

The effective wavelength band of far infrared rays is preferably 2 to 20. Mu.m, more preferably 3 to 7. Mu.m, from the viewpoint of promoting homogeneous melt bonding of TFE-based polymers.

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

The atmosphere at the time of firing is preferably a gas atmosphere composed of an inert gas and having a low oxygen concentration, and preferably a gas atmosphere composed of nitrogen and having an oxygen concentration (volume basis) of less than 500 ppm. The oxygen concentration (volume basis) is particularly preferably 300ppm or less. In addition, the oxygen concentration (volume basis) is usually 1ppm or more.

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

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

In the case where the resin layer in the resin-coated metal foil is a conventional insulating material (cured product of a thermosetting resin such as polyimide), a long time of heating 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 reduced. Thus, the manufacturing method of the present invention is a method of reducing the thermal load on the metal foil when forming the resin layer on the metal foil with resin, and is also a method of reducing damage to the metal foil.

In the resin-coated metal foil of the present invention, the surface of the F resin layer may be subjected to a surface treatment in order to control the linear expansion coefficient 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 to 190 ℃, particularly preferably 120 to 180 ℃.

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

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

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

Examples of the gas used for the plasma treatment include oxygen gas, nitrogen gas, a rare gas (such as argon gas), hydrogen gas, and ammonia gas, and preferably a rare gas or nitrogen gas. Specific examples of the gas used for the plasma treatment include argon gas, a mixed gas of hydrogen and nitrogen gas, and a mixed gas of hydrogen, nitrogen 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% by volume or more, and particularly preferably an atmosphere in which the volume fraction is 100% by volume. 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 uniformity and is less likely to warp, and therefore can be easily laminated with other substrates.

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

The prepreg is a sheet-like substrate obtained by impregnating a base material (short chips, woven fabric, etc.) of reinforcing fibers (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 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 crystalline polyester.

As a method of laminating another base material on the surface of the F resin layer of the resin-coated metal foil of the present invention, there is a method of hot-pressing the resin-coated metal foil with another substrate.

The pressing temperature in the case where the other substrate is a prepreg is preferably not higher than the melting point of the TFE-based 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 pressurizing 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 under a reduced pressure atmosphere, and particularly preferably performed under a vacuum of 20kPa or less. Within this range, the incorporation of bubbles into the interfaces of the F resin layer, the substrate, and the metal foil in the laminate can be suppressed, and deterioration due to oxidation can be suppressed.

In the hot pressing, it is preferable to raise the temperature after the vacuum degree is reached. If the temperature is raised before reaching the vacuum degree, the F resin layer is softened, that is, the F resin layer is pressure-bonded with 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 the laminate of the present invention can be used for manufacturing printed boards as a flexible copper-clad laminate or a rigid copper-clad laminate.

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

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

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

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

Examples

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

Various measurement methods are shown below.

< 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 Searcher's equipment Co., ltd.).

< storage modulus of Polymer >

The storage modulus at 260℃was measured by using a dynamic viscoelasticity measuring apparatus (DMS 6100, manufactured by SII nano science and technology Co., ltd., SII Ind.) according to ISO 6721-4:1994 (JIS K7244-4:1999) and by raising the temperature from 20℃at a rate of 2℃per minute under the conditions of a frequency of 10Hz, a static force of 0.98N and a dynamic displacement of 0.035%.

< D50 and D90 of powder >)

The powder was dispersed in water and measured using a laser diffraction/scattering particle size distribution measuring apparatus (manufactured by horiba corporation, LA-920 measuring apparatus).

< homogeneity of resin layer >

The resin layer irradiated with the light was observed from obliquely above, and evaluated according to the following criteria.

O: no pattern was confirmed.

Delta: the pattern of the shaddock peel shape was confirmed.

X: the pattern of the shaddock peel was confirmed, and the resin was mainly confirmed to be dropped at the end.

< warp Rate of resin-coated Metal foil >

A square test piece having a square shape of 180mm was cut from the resin-coated metal foil, and the test piece was measured according to the measurement method defined in JIS C6471:1995.

O: the warping rate of the resin-coated metal foil is 5% or less.

Delta: the warping rate of the resin-coated metal foil is more than 5% and 7% or less.

X: the warp rate of the metal foil with resin is more than 7%.

[ TFE-based Polymer ]

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

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

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 mole% or more TFE-based units.

[ dispersant ]

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

[ Metal foil ]

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

[ powder ]

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

Powder 2: powder of Polymer 2 with D50 of 2.4 μm and D90 of 5.5. Mu.m.

Powder 3: powder of Polymer 3 having D50 of 3.1 μm and D90 of 5.9. Mu.m.

Powder 4: powder of Polymer 4 with D50 of 0.3 μm and D90 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 to the surface of the copper foil 1 using a die coater, and the copper foil 1 was passed through a through-air drying oven (atmosphere temperature: 260 ℃ C., atmosphere gas: nitrogen gas having an oxygen concentration of 8000 ppm) and kept for 1 minute, and further passed through a far-infrared oven (temperature: 340 ℃ C., gas: nitrogen gas having an oxygen concentration of less than 100 ppm) and kept for 1 minute, to obtain a resin-coated copper foil having a resin layer (thickness 5 μm) of the polymer 1 on the surface of the copper foil 1. The evaluation results concerning the homogeneity of the resin layer and the warp rate of the metal foil with resin are shown in table 1 below.

Examples 2 to 5

A copper foil with resin was obtained in the same manner as in example 1 except that the atmosphere temperature of the powder and the air-drying oven was changed, and each evaluation was performed. The results are summarized in Table 1 below.

TABLE 1

Industrial applicability

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

The entire contents of the specification, claims and abstract of japanese patent application No. 2018-104010, to which the application was filed on 5/30 of 2018, are incorporated herein by reference as the disclosure of the specification of the present invention.

Claims

1. A process for producing a resin-coated metal foil, which comprises applying a powder dispersion comprising a tetrafluoroethylene polymer having a storage modulus of 0.1 to 5.0MPa in a temperature range of 260 ℃ or less and a melting point of more than 260 ℃ to a surface of a metal foil having a thickness of 1 μm or more and less than 10 μm and a solvent to the surface of the metal foil,

maintaining the metal foil at a temperature within said temperature range and at a temperature comprising 1 x 10 on a volume basis ² ～3×10 ⁵ In an atmosphere of oxygen in ppm of water,

further, the tetrafluoroethylene polymer is fired at a temperature greater than the temperature range and in an atmosphere composed of nitrogen and containing 1ppm or more and less than 500ppm of oxygen by volume basis, thereby forming a resin layer containing the tetrafluoroethylene polymer on the surface of the metal foil.

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

3. The method according to claim 1 or 2, wherein the cumulative 50% by volume of the powder has a diameter of 0.05 to 6.0. Mu.m.

4. The production method according to claim 1 or 2, wherein the tetrafluoroethylene 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.

5. The method according to claim 1 or 2, wherein the tetrafluoroethylene polymer has at least one functional group selected from the group consisting of carbonyl group-containing, hydroxyl group, epoxy group, amide group, amino group and isocyanate group.

6. The method of manufacturing as claimed in claim 1 or 2, wherein the powder dispersion comprises a polymer-like polyol.

7. The manufacturing method according to claim 1 or 2, wherein the time for which the metal foil is kept in the temperature range is 30 seconds to 5 minutes.

8. The method according to claim 1 or 2, wherein the temperature at which the tetrafluoroethylene polymer is fired is higher than 320 ℃.

9. A method for producing a printed circuit board, wherein a metal foil with a resin is produced by the production method according to any one of claims 1 to 8, and the metal foil is etched to form a pattern circuit.