JP7746367B2 - Aqueous surface treatment agent and laminate - Google Patents

Description

The present invention relates to an aqueous surface treatment agent and a laminate.

Currently, devices that utilize high-frequency radio waves are being developed in preparation for the widespread adoption of fifth-generation mobile communication systems, and demand is increasing for printed circuit boards that can transmit high-frequency signals.

Copper foil, such as rolled copper foil or electrolytic copper foil, is used as the material for such printed wiring boards. Traditionally, copper foil has been used after its surface has been roughened to improve adhesion with the resin film.

However, roughening the surface of copper foil can cause electrical signals to attenuate during high-frequency signal transmission, resulting in increased transmission loss.

On the other hand, if it were possible to ensure adhesion between the copper foil and the resin film without roughening the surface of the copper foil, it would be possible to reduce the transmission loss caused by the roughening treatment, and it would also be possible to simplify the manufacturing process and reduce costs.

In response to this, for example, Patent Document 1 discloses a copper surface treatment agent that can smooth the copper surface without roughening treatment such as etching, and that can maintain adhesion between copper and insulating materials such as resin. The copper surface treatment agent contains a tin compound, a complexing agent, and a water-soluble or water-dispersible polymer, and the water-soluble or water-dispersible polymer has at least one functional group selected from the group consisting of amino groups, epoxy groups, thiol groups, carboxyl groups, sulfonic acid groups, hydroxyl groups, phosphate groups, imino groups, and silanol groups.

International Publication No. 2010/010716

However, it was found that there was room for further improvement in the adhesion between the copper foil and the resin film.

The present invention therefore aims to provide a surface treatment agent that achieves excellent adhesion between copper foil and a resin film without roughening the copper foil surface.

Another object of the present invention is to provide a laminate having a metal and a coating of an aqueous surface treatment agent that provides excellent adhesion to a resin film.

The aqueous surface treatment agent according to the present invention is an aqueous surface treatment agent used for metal surface treatment,
a nitrogen-containing silane coupling agent;
an amide group-containing resin,
The amide group-containing resin is an aqueous surface treatment agent having an amide group in the side chain, which allows excellent adhesion between the copper foil and the resin film to be obtained without roughening the surface of the copper foil.

In one embodiment of the aqueous surface treatment agent according to the present invention, the amide group is —CO—NH ₂ .

In one embodiment of the aqueous surface treatment agent according to the present invention, the amide group-containing resin is polyacrylamide.

In one embodiment of the aqueous surface treatment agent according to the present invention, the nitrogen-containing silane coupling agent has one or more groups selected from the group consisting of amino groups and imino groups.

The laminate according to the present invention comprises, in order:
Metal and
A film of any one of the aqueous surface treatment agents described above;
The laminate has the following structure.

In one embodiment of the laminate according to the present invention, the metal is copper or a copper alloy.

In one embodiment of the laminate according to the present invention, the laminate comprises, in order:
The metal;
The coating;
A resin film;
It has.

In one embodiment of the laminate according to the present invention, the laminate is a flexible printed wiring board.

The present invention provides a surface treatment agent that provides excellent adhesion between copper foil and a resin film without requiring a roughening treatment of the copper foil surface. The present invention also provides a laminate comprising a metal and a coating of an aqueous surface treatment agent that provides excellent adhesion to a resin film.

The following describes embodiments of the present invention. These descriptions are intended to exemplify the present invention and are not intended to limit the present invention in any way.

In the present invention, two or more embodiments can be combined in any manner.

In this invention, the term "solid content" is a concept that encompasses both solid content and non-volatile content.

Unless otherwise specified, the materials, components, compounds, resins, groups, and solvents described in this specification may be used alone or in combination of two or more.

In this specification, unless otherwise specified, numerical ranges are intended to include the upper and lower limits of the range. For example, 1 to 20% by mass means a range of 1% by mass or more and 20% by mass or less.

In this specification, the nitrogen-containing silane coupling agent and the amide group-containing resin may be referred to as component (A) and component (B), respectively.

If a compound is both a nitrogen-containing silane coupling agent and an amide group-containing resin, the compound is treated as a silane coupling agent, not an amide group-containing resin.

In this specification, "-co-" indicates a copolymer containing repeating units based on the monomers on both sides. For example, acrylamide-co-acrylic acid indicates a copolymer containing repeating units based on acrylamide and repeating units based on acrylic acid. Furthermore, "-co-" does not specify the arrangement of the repeating units in the copolymer, meaning that they may be random, alternating, periodic, or block.

Aqueous Surface Treatment Agent The aqueous surface treatment agent according to the present invention is an aqueous surface treatment agent used for metal surface treatment,
a nitrogen-containing silane coupling agent;
an amide group-containing resin,
The amide group-containing resin is an aqueous surface treatment agent having an amide group on the side chain.

The following describes examples of each component of the aqueous surface treatment agent according to the present invention.

Component (A): Nitrogen-Containing Silane Coupling Agent As the component (A), a known nitrogen-containing silane coupling agent can be used.

Examples of nitrogen-containing groups contained in component (A) include amino groups (-NH ₂ ), imino groups (=NR, -N(R)-), quaternary ammonium groups (-N ⁺ R ₃ ), ureido groups (-NHCONH ₂ ), isocyanate groups (-N=C=O), and isocyanurate groups. In one embodiment, component (A) contains one or more groups selected from the group consisting of amino groups, imino groups, quaternary ammonium groups, ureido groups, isocyanate groups, isocyanurate groups, and benzotriazole groups. In another embodiment, component (A) contains one or more groups selected from the group consisting of amino groups and imino groups.

Component (A) may have a nitrogen-containing aromatic ring. Component (A) may have, for example, residues of pyrrole, pyrazole, imidazole, triazole, tetrazole, oxazole, oxadiazole, isoxazole, thiazole, isothiazole, furazan, pyridine, pyridazine, pyrimidine, pyrazine, triazine, tetrazine, azepine, diazepine, triazepine, etc.; residues of indole, isoindole, indazole, purine, quinoline, isoquinoline, benzotriazole, etc.; residues of carbazole, acridine, β-carboline, acridone, perimidine, phenazine, phenanthridine, phenothiazine, phenoxazine, phenanthroline, etc.; residues of quindoline, quinindoline, etc.; residues of acryldoline, etc.

Examples of component (A) include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, and N-2-(aminoethyl)-8-aminooctyl Examples include trimethoxysilane, N-2-(aminoethyl)-1-aminomethyltrimethoxysilane, 3-ureidopropyltrialkoxysilane, 3-ureidopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, tris(trimethoxysilylpropyl)isocyanurate, 3-isocyanatopropyltriethoxysilane, [3-(6-aminohexylamino)propyl]trimethoxysilane, bis[3-(trimethoxysilyl)propyl]amine, bis[3-(triethoxysilyl)propyl]amine, and N,N'-bis[3-(trimethoxysilyl)propyl]ethylenediamine. Other examples include X-12-1290 (containing an isocyanurate group), X-12-1214A (containing a benzotriazole group), and X-12-1172ES (containing an imino group) manufactured by Shin-Etsu Chemical Co., Ltd., and VD-5 (containing a triazine ring) manufactured by Shikoku Chemical Industry Co., Ltd.

In a preferred embodiment, component (A) is one or more selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane.

The content of component (A) in the aqueous surface treatment agent can be adjusted as appropriate. For example, the content of component (A) can be 80 to 99 mass% based on the total amount of solids in the aqueous surface treatment agent.

In one embodiment, the total concentration of components (A) and (B) relative to the entire aqueous surface treatment agent is 100 to 30,000 ppm.

In one embodiment, the ratio of the mass M _A of component (A) to the mass M _B of component (B) (M _A /M _B ) is 3 or greater. In another embodiment, the ratio M _A /M _B is 3 or greater, 4 or greater, 5 or greater, 10 or greater, 20 or greater, 30 or greater, 40 or greater, 50 or greater, 60 or greater, 70 or greater, 80 or greater, 90 or greater, 100 or greater, 150 or greater, 200 or greater, or 300 or greater. In yet another embodiment, the ratio M _A /M _B is 500 or less, 400 or less, 300 or less, 200 or less, 150 or less, 100 or less, 90 or less, 80 or less, 70 or less, 60 or less, 50 or less, 40 or less, 30 or less, 20 or less, 10 or less, or 5 or less. In yet another embodiment, the ratio M _A /M _B is 3 to 100.

Component (B): Amide Group-Containing Resin As component (B), a known amide group-containing resin having an amide group in the side chain can be used. Examples of component (B) include polyamide having an amide group in the side chain, polyacrylamide having an amide group in the side chain, and polyacrylamide copolymer having an amide group in the side chain.

Examples of polyacrylamides having amide groups in their side chains include cationic polyacrylamides and nonionic polyacrylamides.

Examples of component (B) include polyacrylamide (Sigma-Aldrich catalog number: 535311; hereafter, the numbers in parentheses in this paragraph represent Sigma-Aldrich catalog numbers), poly(N-isopropylacrylamide), poly(acrylamide-co-acrylic acid) potassium salt (432776), poly(N-isopropylacrylamide) carboxylic acid thiol terminal (806366), poly(N-isopropylacrylamide) N-hydroxysuccinimide ester terminal (900188), poly(acrylamide-co-acrylic acid) sodium salt (511471), poly(N-isopropylacrylamide) amine terminal (724823), poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylonitrile) (191981), poly(N-isopropylacrylamide) carboxylic acid terminal (724807), poly Examples include (N-isopropylacrylamide-co-methacrylic acid) (724858), poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (191973), poly(N,N-dimethylacrylamide) dodecyltrithiocarbonate-terminated (773638), poly(acrylamide-co-diallyldimethylammonium chloride) (409081), poly(N-isopropylacrylamide) azide-terminated (747068), poly(ethylene glycol)-block-poly(N-isopropylacrylamide) (747181), poly(N-(2-hydroxypropyl)methacrylamide) (804746), poly(N-isopropylacrylamide-co-butyl acrylate) (762857), and poly[(2-ethyldimethylammonioethyl methacrylate ethyl sulfate)-co-(1-vinylpyrrolidone)] (190888).

In addition to the above, commercially available products of component (B) include those manufactured by Harima Chemicals Co., Ltd. under the trade names "Haricoat G35," "Haricoat G50," "Haricoat G51," "Haricoat GA-1," and "Haricoat 1057"; Sigma-Aldrich catalog number: 725668; and those manufactured by Nittobo Medical Co., Ltd. under the trade names "PAS-2141CL," "PAS-J-81L," "PAS-J-81," and "PAS-J-41."

Component (B) may be an amide-modified resin that is made by starting with a resin having a functional group other than an amide group in its side chain and modifying that functional group to introduce an amide group.

Component (B) may be in the form of water-soluble, emulsion, or dispersion.

In one embodiment, the amide group of component (B) is —CO—NH ₂ .

In one embodiment, component (B) is polyacrylamide. In another embodiment, component (B) comprises one or more selected from the group consisting of cationic polyacrylamides and nonionic polyacrylamides. In another embodiment, component (B) comprises one or more selected from the group consisting of cationic polyacrylamides and nonionic polyacrylamides. In yet another embodiment, component (B) comprises one or more selected from the group consisting of Sigma-Aldrich catalog numbers 432776, 511471, and 409081 and Nittobo Corporation trade names "PAS-2141CL," "PAS-J-81L," "PAS-J-81," and "PAS-J-41." In yet another embodiment, component (B) is one or more selected from the group consisting of Sigma-Aldrich catalog numbers 432776, 511471, and 409081 and Nittobo Corporation product names "PAS-2141CL," "PAS-J-81L," "PAS-J-81," and "PAS-J-41."

The content of component (B) in the aqueous surface treatment agent can be adjusted as appropriate. For example, the content of component (B) can be 1 to 20 mass% based on the total amount of solids in the aqueous surface treatment agent.

In addition to components (A) and (B), the aqueous surface treatment agent according to the present invention may contain components used in known surface treatment agents. Examples of aqueous surface treatment agents include solvents such as water, alcohol, and acetone; water-soluble polymers and water-dispersible polymers described in Patent Document 1; resins; pH adjusters; rust inhibitors; condensates of components (A) themselves; and condensates of component (A) with other components.

Solvent The aqueous surface treatment agent according to the present invention may further contain a water-miscible organic solvent, as necessary, in order to adjust the solid content concentration or drying speed. Examples of water-miscible organic solvents include ketone solvents such as acetone and methyl ethyl ketone; amide solvents such as N,N'-dimethylformamide and dimethylacetamide; alcohol solvents such as methanol, ethanol, isopropyl alcohol and 1-methoxy-2-propanol; ether solvents such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; and pyrrolidone solvents such as 1-methyl-2-pyrrolidone and 1-ethyl-2-pyrrolidone.

Any known water can be used, such as distilled water, purified water, deionized water, or tap water.

The aqueous surface treatment agent of this embodiment may contain known acids, bases, surface conditioners, and defoamers that are commonly blended into conventional aqueous surface treatment agents.

The method for preparing the aqueous surface treatment agent is not particularly limited, and the aqueous surface treatment agent can be prepared by mixing the components (A) and (B). In addition to the components (A) and (B), other components such as a solvent may also be mixed in any order.

The laminate according to the present invention is a laminate having, in order, a metal and a coating of an aqueous surface treatment agent, thereby achieving excellent adhesion between the metal and the resin film via the coating of the aqueous surface treatment agent.

Metal The metal is not particularly limited as long as it is a metal that is required to have adhesion to the resin film, and known metals can be used, such as copper, nickel, and aluminum.

Examples of copper include rolled copper foil and electrolytic copper foil. Copper may also be a copper alloy with, for example, tin, zinc, nickel, arsenic, silicon, titanium, or chromium. In one embodiment, the metal of the laminate is copper or a copper alloy. In another embodiment, the metal of the laminate is one or more selected from the group consisting of rolled copper foil and electrolytic copper foil.

The metal in the laminate of the present invention may be a roughened or unroughened metal. Because the laminate of the present invention contains a coating of the aqueous surface treatment agent of the present invention, excellent adhesion to the resin film can be obtained even with unroughened metal. In one embodiment, the metal in the laminate is an unroughened metal.

The surface roughness of one side of the metal may be, for example, Rz (ten-point average roughness) of 10 μm or less, 5 μm or less, 3 μm or less, 2 μm or less, 1.5 μm or less, 1.4 μm or less, 1.3 μm or less, 1.2 μm or less, 1.1 μm or less, 1.0 μm or less, 0.9 μm or less, 0.8 μm or less, 0.7 μm or less, 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, 0.2 μm or less, or 0.1 μm or less. Furthermore, the surface roughness of one side of the metal may be, for example, Rz of 0.1 μm or more. Rz can be measured in accordance with JIS B0601 (2013) using a commercially available laser microscope, OPTELICS HYBRID, manufactured by Lasertec Corporation.

The thickness of the metal can be adjusted as appropriate, for example, between 1 and 200 μm. In one embodiment, the metal thickness is 1 μm or more, 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 100 μm or more, or 150 μm or more. In another embodiment, the metal thickness is 200 μm or less, 150 μm or less, 100 μm or less, 50 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, or 10 μm or less.

- Film of aqueous surface treatment agent The film of aqueous surface treatment agent is a film formed using the aqueous surface treatment agent of the present invention.

In the laminate, the metal and the film of the aqueous surface treatment agent need only be arranged in this order. The metal and the film of the aqueous surface treatment agent may be laminated adjacent to each other, i.e., in direct contact with each other, or another layer or film may be sandwiched between the metal and the film of the aqueous surface treatment agent.

The coating of the aqueous surface treatment agent needs to be layered on at least a portion of at least one surface of the metal, and may be layered on the entire surface of one or both surfaces (both opposing surfaces) of the metal.

In one embodiment of the laminate according to the present invention, the laminate comprises, in order, the metal, the coating, and a resin film.

Resin Film The resin film is not particularly limited, and known resin films can be used. Examples of the resin film include polyimide films, modified polyimide (MPI) films, polyamide films, polyester films (e.g., polyethylene terephthalate films, poly-1,4-cyclohexanedimethylene terephthalate films, etc.), liquid crystal polymer films, polycarbonate films, cycloolefin polymer films, and fluororesin films, which are used for printed wiring boards.

The thickness of the resin film may be adjusted as appropriate and is, for example, 5 to 200 μm. In one embodiment, the thickness of the resin film is 5 μm or more, 10 μm or more, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 100 μm or more, or 150 μm or more. In another embodiment, the thickness of the resin film is 200 μm or less, 150 μm or less, 100 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 15 μm or less, or 10 μm or less.

Other Layers or Films Examples of layers or films that may be disposed between the metal and the film of the aqueous surface treatment agent include plating and chromate films formed by surface treatment of the metal.

Examples of plating include Ni plating, Ni-P plating, Ni-Co plating, Ni-Mo plating, Zn plating, Zn-Ni plating, Cu-Zn plating, Cu-Ni plating, and Cu-Ni-Co plating.

Applications of the laminate of the present invention are not particularly limited, and examples include flexible printed wiring boards, home appliances, information terminals, and building materials.

In one embodiment of the laminate according to the present invention, the laminate is a flexible printed wiring board.

- Manufacturing method of laminate The manufacturing method of the laminate is not particularly limited as long as it can laminate the metal and the aqueous surface treatment agent in order to form a film of the aqueous surface treatment agent, and known manufacturing methods for flexible printed wiring boards, etc. Examples of the manufacturing method of the laminate include a method including a step of preparing a metal and an aqueous surface treatment agent, a step of applying the surface treatment agent to at least a portion of at least one side of the metal, and a step of heating or drying the applied surface treatment agent to form a film of the surface treatment agent.

The method for applying the surface treatment agent is not particularly limited, and any known application method can be used. Examples of application methods include immersion, bar coating, roll coating, shower coating, spraying, and brush coating.

The heating or drying temperature for the surface treatment agent is not particularly limited, but is, for example, 50 to 250°C.

The heating or drying time for the surface treatment agent is not particularly limited, but is, for example, 2 seconds to 1 hour.

The thickness of the coating is not particularly limited and can be adjusted as appropriate. For example, the dry thickness of the coating is 1 nm to 10 μm.

When the laminate has a configuration of metal/aqueous surface treatment agent film/resin film, one example of a manufacturing method is to form a laminate of metal/aqueous surface treatment agent film, then place a resin film on the film, and then press the metal, aqueous surface treatment agent film, and resin film together.

The temperature used for pressure bonding is, for example, 100 to 450°C.

The pressure used for crimping is, for example, 0.1 to 10 MPa.

The present invention will be explained in more detail below with reference to examples. However, these examples are intended to illustrate the present invention and are not intended to limit the present invention in any way.

The materials used in the examples are as follows:
(A) Component A1: 3-aminopropyltrimethoxysilane, trade name "KBM-903"
A2: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, trade name "KBM-603"
A3: 3-aminopropyltriethoxysilane, trade name "KBE-903"
A4: N-(2-aminoethyl)-3-aminopropyltriethoxysilane, product name "KBE-603"
A5: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name "KBM-602"
A6: N-phenyl-3-aminopropyltrimethoxysilane, trade name "KBM-573"
Comparative silane coupling agents Comparative silane coupling agent 1: vinyltriethoxysilane, trade name "KBE-1003", indicated as "CS1" in the table Comparative silane coupling agent 2: 3-methacryloxypropyltriethoxysilane, trade name "KBE-503", indicated as "CS2" in the table A1 to A6 and CS1 to CS2 are all manufactured by Shin-Etsu Chemical Co., Ltd.
(B) Component B1: Nonionic polyacrylamide having amide groups in the side chains, trade name "Haricoat 1057" manufactured by Harima Chemicals Co., Ltd.
B2: Anionic polyacrylamide having amide groups in the side chains, trade name "Haricoat G-50" manufactured by Harima Chemicals Co., Ltd.
B3: Product name "PAS-2141CL" manufactured by Nittobo Medical Co., Ltd.
B4: Poly(N-isopropylacrylamide) manufactured by Sigma-Aldrich
Comparative amide group-containing resin: "AQ Nylon T-70" manufactured by Toray Industries, a nylon having an amide group on the main chain, designated "CA1" in the table.

The devices and materials used in the examples are as follows:
Press machine: Product name "PYS-10" manufactured by Kodaira Manufacturing Co., Ltd.
Electrolytic copper foil: chromate-treated electrolytic copper foil having a thickness of 20 μm. This electrolytic copper foil was not roughened.
Load measuring device: MinebeaMitsumi product name "LTS-200N-S100"
Polyimide film: UBE product name "UPILEX (registered trademark)-25VT", thickness 25 μm

Examples 1 to 22 and Comparative Examples 1 to 6
Component (A), component (B), and deionized water were mixed to give the concentrations shown in Table 1 to prepare aqueous surface treatment agents.

Preparation of Laminate: Unroughened electrolytic copper foil was immersed in the aqueous surface treatment agent of Example 1 for 5 seconds and then removed. The electrolytic copper foil was then dried at 120°C for 30 seconds to form a coating of the aqueous surface treatment agent on the surface of the electrolytic copper foil. An intermediate was then placed in a press with a layer structure of electrolytic copper foil/aqueous surface treatment agent coating/polyimide film. The press was then heated to 300°C over 1 hour. While maintaining the temperature at 300°C, a pressure of 5.8 MPa was applied to the intermediate from both the electrolytic copper foil side and the polyimide film side in the press, and the temperature was maintained at 300°C for 30 minutes. A three-layer laminate of electrolytic copper foil/aqueous surface treatment agent coating/polyimide film was then obtained.

For Examples 2 to 22 and Comparative Examples 1 to 6, the aqueous surface treatment agent was changed, and a three-layer laminate consisting of electrolytic copper foil, aqueous surface treatment agent coating, and polyimide film was obtained in the same manner as in Example 1.

The obtained laminate was subjected to the following peel strength test to evaluate the adhesion. The results are also shown in Table 1.

Peel strength test: A 10 mm wide x 60 mm long cut was made in the copper foil from the copper foil side of the laminate. Using a load measuring device, the tip of the copper foil was gripped with a gripper, and a 90° peel test was performed over a length of 50 mm at a peel rate of 50 mm/min in accordance with JIS C 6481 to measure the peel strength.

The present invention provides a surface treatment agent that achieves excellent adhesion between copper foil and resin film without roughening the copper foil surface.

The present invention provides a surface treatment agent that provides excellent adhesion between copper foil and a resin film without requiring a roughening treatment of the copper foil surface. The present invention also provides a laminate comprising a metal and a coating of an aqueous surface treatment agent that provides excellent adhesion to a resin film.

Claims (10)

An aqueous surface treatment agent used for metal surface treatment,
a nitrogen-containing silane coupling agent;
an amide group-containing resin,
The amide group-containing resin has an amide group in a side chain,
The aqueous surface treatment agent has a ratio (MA/MB) of _the mass of the nitrogen-containing silane coupling agent, MA, to the mass of the amide group-containing resin, MA _, of 3 _{to 100} . 2. The aqueous surface treatment agent according to claim 1, wherein the amide group is —CO—NH ₂ . The aqueous surface treatment agent according to claim 1, wherein the amide group-containing resin is polyacrylamide. The aqueous surface treatment agent according to claim 1, wherein the nitrogen-containing silane coupling agent has one or more groups selected from the group consisting of amino groups and imino groups. 2. The aqueous surface treatment agent according to claim 1, which is used for direct surface treatment of the metal. In order,
Metal and
A film of the aqueous surface treatment agent according to any one of claims 1 to 5 ;
A laminate having: The laminate of claim 6 , wherein the metal is copper or a copper alloy. In order,
The metal;
The coating;
A resin film;
The laminate of claim 6 , having The laminate according to claim 8 , which is a flexible printed wiring board. The laminate according to claim 6 , wherein the metal and the coating are in direct contact with each other.