Method for producing flexible board

Abstract

The present invention relates to a method for manufacturing a flexible substrate that can suppress incomplete deposition or blistering of the electroless copper plating film, and suppress pitting defects of the electroplated copper film. A method for manufacturing a flexible substrate having a resin substrate and a rolled copper foil formed on a part of the resin substrate, wherein an electroless copper plating film and an electroplated copper plating film are laminated thereon. The manufacturing method comprises a process of forming the electroless copper plating film on the resin substrate and the rolled copper foil by performing an electroless copper plating treatment, and a process of forming the electroplated copper plating film on the electroless copper plating film by performing an electroplated copper plating treatment. The electroless copper plating treatment uses an electroless copper plating solution containing a copper compound, a reducing agent, a tertiary alkanolamine, a nickel compound, and a nitrogen-containing aromatic compound.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a flexible substrate, which is a precursor of a flexible wiring substrate. Background Technology

[0002] Flexible wiring boards are flexible and enable three-dimensional wiring or wiring of moving parts within electronic devices, so they are used in various electronic devices such as portable terminals, LCD TVs, laptop PCs, and digital cameras. Flexible wiring boards are manufactured by forming a wiring pattern on a flexible substrate (precursor) in which a conductive layer is formed as a substrate. Although flexible substrates are manufactured by various known methods, various improvement technologies are being proposed to increase connection reliability.

[0003] For example, Patent Document 1 discloses a bronze plating solution comprising a second copper salt, a reducing agent, at least two types of complexing agents, and a stabilizer, and a method for manufacturing a flexible substrate using said plating solution.

[0004] Patent document 2 discloses an electroless copper plating bath containing a specific phosphine compound as a stabilizer and a method for manufacturing a flexible substrate using said plating bath.

[0005] Patent document 3 discloses a flexible substrate having an electroless copper plating layer formed on a polyimide substrate having a predetermined surface roughness. Prior art literature

[0006] Chinese Patent Publication No. 108559980, Japanese Patent Publication No. 2005-290415, Japanese Patent Publication No. 2012-15448 The problem to be solved

[0007] While electrolytic copper foil or rolled copper foil is used as the conductive layer, rolled copper foil is commonly used in flexible wiring boards for movable parts, such as hinges of electronic devices, where even higher flexibility or fracture resistance is required. Since electrolytic copper foil has a columnar crystal structure developed in the thickness direction, cracks propagate along grain boundaries when bent, causing premature fracture; in contrast, because rolled copper foil has an isotropic crystal structure, cracks are difficult to propagate, and it offers high bending reliability.

[0008] In recent years, flexible substrates have been used in which a conductive layer is formed by combining rolled copper foil, an electroless copper plating film, and an electrolytic copper plating film on a resin substrate; however, due to the electroless copper plating process using a conventional electroless copper plating solution, the following plating film defects have occurred.

[0009] First, i) when using a resin substrate, in conventional electroless copper plating solutions, plating did not deposit on the portions of the resin substrate where rolled copper foil was not formed, even after electroless copper plating treatment, resulting in areas where an electroless copper plating film could not be formed on the resin substrate. Consequently, even if electrolytic copper plating treatment was performed after the electroless copper plating treatment, an electrolytic copper plating film could not be formed on these un-deposited areas, leading to wiring pattern defects or reduced connection reliability caused by these un-deposited areas.

[0010] In addition, ii) in the electroless copper plating film formed on the resin substrate, there were cases where blisters occurred, that is, the electroless copper plating film swelled up and a gap formed between it and the resin substrate. As a result, there were cases where the plating film peeled off from the resin substrate or caused a decrease in connection reliability.

[0011] The present invention is an invention made in consideration of the above problems, and its purpose is to provide a method for manufacturing a flexible substrate that can solve the problems of i and ii. means of solving the problem

[0012] [1] A method for manufacturing a flexible substrate having a copper plating film and an electroless copper plating film laminated on a resin substrate and a rolled copper foil formed on a part of the resin substrate, and

[0013] The above manufacturing method is,

[0014] A process of forming the electroless copper plating film on the resin substrate and rolled copper foil by performing an electroless copper plating treatment.

[0015] The process of forming the electroplated copper film on the electroless copper plating film by performing an electroplated copper plating treatment, and

[0016] The above electroless copper plating treatment uses an electroless copper plating solution containing a copper compound, a reducing agent, a tertiary alkanolamine, a nickel compound, and a nitrogen-containing aromatic compound.

[0017] [2] In the above electroless copper plating solution

[0018] The concentration of the above tertiary alkanolamine is 0.001 g / L to 1000 g / L,

[0019] The concentration of the above nickel compound is 0.0005 g / L to 5 g / L as a nickel concentration,

[0020] A method for manufacturing a flexible substrate as described in [1], wherein the concentration of the nitrogen-containing aromatic compound is 0.00001 g / L to 2 g / L.

[0021] [3] The method for manufacturing a flexible substrate described in [1] or [2], wherein the tertiary alkanolamine is at least one selected from the group consisting of triethanolamine and triisopropanolamine.

[0022] [4] A method for manufacturing a flexible substrate as described in any one of [1] to [3], wherein the nitrogen-containing aromatic compound is at least one selected from the group consisting of bipyridines and phenanthrolines. Effects of the invention

[0023] According to the present invention, a good electroless copper plating film can be formed with no plating deposits and blisters suppressed.

[0024] In addition, according to the present invention, a good electroplated copper film with pitting defects suppressed can be formed.

[0025] Accordingly, according to the manufacturing method of the present invention, a flexible substrate having a good electroless copper plating film and a good electroplated copper film can be provided. Brief explanation of the drawing

[0026] Figure 1 is a schematic diagram illustrating the manufacturing process of a flexible substrate of the present invention. FIG. 2 is a schematic diagram illustrating the manufacturing process of a flexible wiring board using the flexible substrate of the present invention. Specific details for implementing the invention

[0027] The flexible substrate of the present invention can be manufactured by sequentially performing an electroless copper plating treatment and an electrolytic copper plating treatment on the rolled copper foil forming surface of a resin substrate to form an electroless copper plating film and an electrolytic copper plating film. The present invention is particularly characterized by using an electroless copper plating bath having a predetermined composition as a means to solve the above problem.

[0028] The electroless copper plating solution of the present invention comprises a tertiary alkanolamine, a nickel compound, a nitrogen-containing aromatic compound, a copper compound, and a reducing agent. The electroless copper plating solution of the present invention, by means of the synergistic effect of the tertiary alkanolamine, the nickel compound, and the nitrogen-containing aromatic compound,

[0029] 1) Suppresses the failure of electroless copper plating film deposition on the substrate surface,

[0030] 2) Suppression of blistering of the electroless copper plating film formed on the substrate surface, and

[0031] 3) An electroless copper plating film that does not have the same crystal orientation as the rolled copper foil can be formed on the surface of the rolled copper foil.

[0032] In particular, the above 3) is a finding obtained by the inventors as a result of repeated examinations of the problems of i) and ii) above regarding the prior art. That is, it was found that if an electroless copper plating film formed on a rolled copper foil has the same crystal orientation as the rolled copper foil, the electroplated copper film also has the corresponding crystal orientation, and furthermore, such an electroplated copper film lacks surface gloss and pit-like defects occur on the surface of the electroplated copper film. Moreover, circuit defects such as pattern defects or reduced connection reliability occur due to such an electroplated copper film. To avoid these problems, it is effective to form an electroless copper plating film as described in 3).

[0033] When the electroless copper plating solution of the present invention is used, the effects of 1 to 3 above are obtained for the substrate. In addition, the electroless copper plating film formed by performing an electroless copper plating treatment on the electroless copper plating film formed using the electroless copper plating solution of the present invention also suppresses pitting defects.

[0034] First, the electroless copper plating solution of the present invention will be described.

[0035] The electroless copper plating solution of the present invention contains a copper compound, a reducing agent, a tertiary alkanolamine, a nickel compound, and a nitrogen-containing aromatic compound.

[0036] tertiary alkanolamine

[0037] The tertiary alkanolamine not only acts as a complexing agent, but is also particularly effective in forming an electroless copper plating film on the surface of the rolled copper foil (3) that does not have the same crystal orientation as the rolled copper foil, and contributes to suppressing pitting defects in the electroplated copper film formed on the surface of the electroless copper plating film.

[0038] Tertiary alkanolamines are compounds having three or more straight-chain or branched alkanol groups. Tertiary alkanolamines are preferably compounds having alkanol groups having 1 to 18 carbon atoms, and more preferably are trimethanolamine, triethanolamine, tripropanolamine, triisopropanolamine, tributanolamine, tripentanolamine, trihexanolamine, triheptanolamine, trioctanolamine, trinonanolamine, tridecanolamine, tridodecanolamine, tritetradecanolamine, trihexadecanolamine, and trioctadecanolamine. Tertiary alkanolamines are even more preferably triethanolamine and triisopropanolamine.

[0039] One or more tertiary alkanolamines may be used in combination in any proportion.

[0040] If the concentration of the tertiary alkanolamine is too low, the additive effect may not be sufficiently obtained. Furthermore, if the concentration of the tertiary alkanolamine is excessive, there may be areas on the substrate or rolled copper foil that are not coated with the electroless copper plating film, making it impossible to form the electroless copper plating film uniformly (hereinafter referred to as film uniformity).

[0041] The concentration of tertiary alkanolamine in the electroless copper plating solution is preferably 0.001 g / L or more, more preferably 0.005 g / L or more, even more preferably 0.01 g / L or more, and even more preferably 0.5 g / L or more, and preferably 1000 g / L or less, more preferably 600 g / L or less, and even more preferably 200 g / L or less.

[0042] nickel compounds

[0043] Nickel compounds particularly contribute to suppressing blistering of the electroless copper plating film formed on the surface of the substrate 2) above.

[0044] The nickel compound is preferably a water-soluble nickel compound, and more preferably nickel sulfate, nickel nitrate, nickel chloride, nickel acetate, nickel citrate, nickel tartarate, nickel gluconate, etc.

[0045] Nickel compounds may be used in combination in any proportion, either one or two or more types.

[0046] If the concentration of the nickel compound is too low, the addition effect may not be sufficiently achieved. Furthermore, if the concentration of the nickel compound is excessive, film uniformity may not be achieved.

[0047] The concentration of nickel compounds in the electroless copper plating solution is preferably 0.0005 g / L or more, more preferably 0.005 g / L or more, even more preferably 0.05 g / L or more, preferably 5 g / L or less, more preferably 2.5 g / L or less, and even more preferably 0.5 g / L or less.

[0048] nitrogen-containing aromatic compounds

[0049] Nitrogen-containing aromatic compounds particularly contribute to suppressing the non-precipitation of the electroless copper plating film on the surface of the above 1) substrate.

[0050] Nitrogen-containing aromatic compounds are not particularly limited, but preferably pyrrolidines, imidazoles, triazoles, tetrazoles, benzimidazoles, benzotriazoles, piperidines, morpholines, piperazines, pyridines, bipyridines, phenanthrolines, oxazoles, benzoxazoles, pyrimidines, quinolines, and isoquinolines, and more preferably bipyridines and phenanthrolines.

[0051] One or more nitrogen-containing aromatic compounds may be used in combination in any proportion.

[0052] More specifically, 4,4'-dimethyl-2,2'-dipyridyl, 2,2'-biquinolyl, 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine, 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-p,p'-disodium disulfonate, 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine, 2,2'-bis(5,6-dimethyl-1,2,4-triazine), 6,7-dimethyl-2,3-di(2-pyridyl)-quinoxaline, 2,3-bis(2-pyridyl)-6,7-dimethylquinoxaline, 2,2'-bipyridyl, 6,7-diethyl-2,3-di(2-pyridyl)-quinoxaline, It is preferable that it be at least one selected from the group consisting of 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, and 2,9-diphenyl-1,10-phenanthroline.

[0053] If the concentration of nitrogen-containing aromatic compounds is too low, the additive effect may not be sufficiently obtained. Furthermore, if the concentration of nitrogen-containing aromatic compounds is excessive, film uniformity may not be achieved.

[0054] The concentration of nitrogen-containing aromatic compounds in the electroless copper plating solution is preferably 0.00001 g / L or more, more preferably 0.0001 g / L or more, even more preferably 0.001 g / L or more, preferably 2 g / L or less, more preferably 1 g / L or less, even more preferably 0.1 g / L or less, and even more preferably 0.05 g / L or less.

[0055] copper compounds

[0056] Copper compounds are essential compounds for the formation of electroless copper plating films.

[0057] The copper compound above is a water-soluble copper salt, preferably copper sulfate, copper nitrate, copper chloride, copper acetate, copper citrate, copper tartrate, copper gluconate, etc. are examples.

[0058] One or more copper compounds may be used in combination in any proportion.

[0059] If the concentration of the copper compound is too low, the deposition rate is slow, and the plating time may be prolonged. Conversely, if the concentration of the copper compound is too high, the plating solution may become unstable.

[0060] The concentration of copper compounds in the electroless copper plating solution is preferably 0.05 g / L or more, more preferably 0.5 g / L or more, preferably 30 g / L or less, more preferably 10 g / L or less as a copper concentration.

[0061] reducing agent

[0062] A reducing agent known as a reducing agent for copper ions in an electroless copper plating solution may be used. Preferably, the reducing agent is formaldehyde, paraformaldehyde, glyoxylic acid, glyoxylate, aminoboranes such as dimethylamineborane, alkali metal salt of boron hydride, hydrazine, polysaccharide, sugars such as glucose, hypophosphorous acid, hypophosphorous acid, glycolic acid, glycolate, formic acid, formate, etc.

[0063] One or more reducing agents may be used in combination in any proportion.

[0064] The concentration of the reducing agent should be sufficient to contain an amount necessary for the reduction of copper ions. The concentration of the reducing agent in the electroless copper plating solution is preferably 0.01 g / L or more, more preferably 0.5 g / L or more, preferably 100 g / L or less, more preferably 80 g / L or less, and even more preferably 50 g / L or less.

[0065] The electroless copper plating solution of the present invention may also contain, as necessary, a complexing agent, a surfactant, a pH adjuster, a stabilizer, etc., as an optional additive.

[0066] Ignition agent

[0067] In the present invention, a tertiary alkanolamine also acts as a complexing agent. Therefore, other complexing agents do not need to be added, but they may be added optionally. As other complexing agents, known complexing agents used in electroless copper plating solutions may be used. Preferably, the complexing agent is a monocarboxylic acid such as acetic acid or formic acid, and its ammonium, potassium, or sodium salts; a dicarboxylic acid such as malonic acid, succinic acid, adipic acid, maleic acid, or fumaric acid, and its ammonium, potassium, or sodium salts; a hydroxycarboxylic acid such as malic acid, lactic acid, glycolic acid, gluconic acid, or citric acid, and its ammonium, potassium, or sodium salts; or ethylenediaminediacetic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, and their ammonium, potassium, or sodium salts. These include aminopolycarboxylic acids such as ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, or their ammonium, potassium, and sodium salts.

[0068] One or more types of ignition agents may be used in combination in any proportion.

[0069] The concentration of other complexing agents in the electroless copper plating solution should be such that it does not impede the effects of the present invention, preferably 0.0001 g / L or more, more preferably 0.01 g / L or more, preferably 1000 g / L or less, more preferably 500 g / L or less.

[0070] surfactants

[0071] In the present invention, known surfactants used in electroless copper plating solutions may be used. The surfactants may include ionic surfactants, nonionic surfactants, and amphoteric surfactants, and may be appropriately selected and used.

[0072] One or more surfactants may be used in combination in any proportion.

[0073] The concentration of the surfactant in the electroless copper plating solution is not particularly limited, preferably 0.000001 g / L or more, more preferably 0.00001 g / L or more, preferably 5 g / L or less, more preferably 2 g / L or less.

[0074] pH adjuster

[0075] In the present invention, it is preferable to add a pH adjusting agent as needed to appropriately adjust the pH of the electroless copper plating solution to the following range.

[0076] Known pH adjusters used in electroless copper plating solutions may be used. The pH adjusters are preferably basic compounds, inorganic acids, or organic acids, and more preferably inorganic acids such as sulfuric acid, hydrochloric acid, or phosphoric acid, and sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, rubidium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, or butylammonium hydroxide.

[0077] One or more pH adjusters may be used in combination in any ratio.

[0078] pH of electroless copper plating solution

[0079] The pH of the electroless copper plating solution is preferably in the range from acidic to alkaline, more preferably from neutral to alkaline. Specifically, the pH of the electroless copper plating solution is preferably pH 2 or higher, more preferably pH 7 or higher, and preferably pH 13 or lower.

[0080] Hereinafter, a method for manufacturing a flexible substrate of the present invention will be described.

[0081] Suji's writing

[0082] The resin substrate (1) is not particularly limited as long as it is a resin substrate having the required flexibility, and various known resin substrates can be used (Fig. 1 (a)). For example, a substrate made of a resin with excellent heat resistance, such as polyimide or polyethylene terephthalate (PET), is preferred. Polyimide-based substrates or PET-based substrates have low dimensional stability and thermal shrinkage, and also have excellent flexibility.

[0083] Rolled copper foil

[0084] Rolled copper foil (2) is laminated on at least one surface of the resin substrate (1) (Fig. 1 (b)). Rolled copper foil (2) may be laminated on both sides of the resin substrate (1). Additionally, the rolled copper foil may be laminated on at least a portion of the surface of the resin substrate. Various known methods may be adopted for the raw material, manufacturing method, and method of laminating the rolled copper foil onto the resin substrate. Furthermore, in the present invention, a resin substrate having a known rolled copper foil that is commercially available may be used. The size and wiring pattern of the rolled copper foil can be appropriately selected according to the required characteristics.

[0085] The flexible substrate of the present invention has an electroless copper plating film formed on both the surface of a rolled copper foil and the surface of a substrate. In the present invention, it is preferable to use a flexible substrate in which a line and space pattern is formed on a rolled copper foil. Specifically, a flexible substrate used for flexible displays or connectors for FPCs is exemplified.

[0086] Pretreatment process

[0087] Before performing electroless copper plating, appropriate pretreatment may be performed on the resin substrate having rolled copper foil as necessary. Examples of pretreatment include various known processes such as degreasing, conditioning, pickling, sensitization (catalyst application), and adhesion promotion.

[0088] Electroless copper plating

[0089] In the present invention, an electroless copper plating treatment is performed to form an electroless copper plating film on the rolled copper foil forming surface of a resin substrate. The resin substrate is immersed in an electroless copper plating solution to form an electroless copper plating film (3) on the surface of the substrate (1) and on the surface of the rolled copper foil (2) (Fig. 1 (c)).

[0090] The electroless copper plating solution of the present invention is used for electroless copper plating treatment. In the present invention, treatment conditions other than using the electroless copper plating solution are not limited, and known electroless copper plating treatment conditions may be adopted.

[0091] The film thickness of the electroless copper plating film can be appropriately adjusted according to the required characteristics. It is desirable that the electroless copper plating film be of a thickness sufficient so that it does not dissolve during the electroplating process.

[0092] The film thickness of the electroless copper plating film is preferably 0.01 μm or more, more preferably 0.1 μm or more, preferably 5 μm or less, more preferably 2 μm or less.

[0093] Pretreatment process

[0094] Before performing electroplating copper, appropriate pretreatment may be performed on the surface of the electroless copper plating film as necessary. Various known processes, such as degreasing, conditioning, and pickling, are examples of pretreatment.

[0095] Electroplating of copper

[0096] In the present invention, an electroplating treatment is performed to form an electroplated copper film (4) on the surface of an electroless copper plating film (3) ((d) of FIG. 1).

[0097] The composition of the copper plating solution used for the copper plating process is not particularly limited. For example, known copper plating solutions, such as the copper plating solution used in the examples, may be used. Furthermore, the copper plating conditions are not limited, and known copper plating conditions may be adopted.

[0098] The film thickness of the electroplated copper film can be appropriately changed according to the required characteristics. The thickness of the conductive layer may also be adjusted by appropriately adjusting the film thickness of the electroplated copper film.

[0099] The thickness of the electroplated copper film is preferably 0.1 μm or more, more preferably 1 μm or more, preferably 100 μm or less, more preferably 50 μm or less.

[0100] By electroplating copper, a multilayer flexible substrate is obtained in which an electroless copper plating film and an electroplated copper plating film are laminated in this order on a resin substrate and on a rolled copper foil.

[0101] A flexible wiring substrate is obtained by forming a wiring pattern on the flexible substrate of the present invention (Fig. 2 (a)) by a known method.

[0102] For example, a resist layer (5) is provided on an electroplated copper film (4), and the resist layer (5) is patterned into a desired circuit pattern (Fig. 2(b)), the exposed electroplated copper film (4) and the underlying electroless copper film (3) are etched away (Fig. 2(c)), and then the resist layer (5) is peeled off to obtain a flexible wiring substrate (Fig. 2(d)).

[0103] By using the flexible substrate of the present invention, a flexible wiring substrate is obtained that is free from defects such as wiring defects or open circuits.

[0104] [Example]

[0105] The present invention will be explained more specifically below with reference to examples, but the present invention is not, of course, limited by the following examples. It is also possible to implement the invention with appropriate modifications within the scope suitable for the purpose of the preceding and subsequent descriptions, and all such modifications are included within the technical scope of the present invention. Furthermore, in the following, unless otherwise specified, "part" means "parts by mass" and "%" means "mass%".

[0106] Experiment 1

[0107] A polyimide film (Kapton 200EN, manufactured by Toray DuPont: size 50 mm × 50 mm) was used as the resin substrate. A high-performance rolled copper foil HA-V2 was prepared by forming a line and pattern (manufactured by JX Metal: each line width 1 mm × line length 50 mm, space width 1 mm) on the surface of this polyimide film.

[0108] Each sample was prepared by performing a pretreatment on this polyimide film according to the process table shown in Table 1, and then performing an electroless copper plating treatment using an electroless copper plating solution with the compositions shown in Tables 2 to 7, so that an electroless copper plating film was formed on the surface of the resin substrate and the surface of the rolled copper foil.

[0109] The following two points were evaluated for the electroless copper plating film of the sample.

[0110] (1) The presence or absence of unprecipitated portions in the electroless copper plating film was visually confirmed.

[0111] Areas where the polyimide film is exposed, i.e., areas where the electroless copper plating film has not deposited, were evaluated as "defective," and areas without deposited areas were evaluated as "good."

[0112] (2) The presence or absence of blisters on the electroless copper plating film was checked visually.

[0113] If there is one or more blisters on the electroless copper plating film on the polyimide film, it was evaluated as "present," and if there are no blisters, it was evaluated as "absent."

[0114] Experiment 2

[0115] In the same manner as in Experiment 1, after performing electroless copper plating treatment, the electroless copper plating film was subjected to the pickling cleaner treatment and pickling treatment shown in Table 1, and then electroplated copper treatment was performed to produce each sample in which an electroplated copper film was formed on the electroless copper plating film.

[0116] The following evaluation was performed on the electroplated copper film of the sample.

[0117] (3) The presence or absence of gloss on the surface of the electroplated copper film of the sample was evaluated using a scanning electron microscope. Glossy cases were classified as "present", and non-glossy cases as "absent".

[0118]

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125] In Tables 2 to 7, each sample of Examples 1 to 62, prepared using the electroless copper plating solution of the present invention, was able to form a good electroless copper plating film on a resin substrate, with (1) no unprecipitated portions and (2) no blisters. In addition, the electroplated copper film formed on the electroless copper plating film had (3) gloss, and the flexible substrate of the present invention had no defects such as pits. Therefore, using the flexible substrate obtained by the manufacturing method of the present invention, a flexible wiring substrate with high reliability can be manufactured.

[0126] Comparative Examples 1 and 2 are examples using an electroless copper plating solution that does not contain nitrogen-containing aromatic compounds, and there were unprecipitated portions of the electroless copper plating film on the resin substrate. Therefore, an electrolytic copper plating film could not be formed on the unprecipitated portions.

[0127] Comparative Examples 3 and 4 are examples using an electroless copper plating solution that does not contain a nickel compound, and blisters occurred on the electroless copper plating film on the resin substrate. As a result, the electroless copper plating film in the blistered portion has poor adhesion to the substrate, and the smoothness of the electroplated copper plating film formed in the blistered portion was reduced.

[0128] Comparative Examples 5 and 6 are examples using an electroless copper plating solution that does not contain nickel compounds or nitrogen-containing aromatic compounds, and there were unprecipitated portions of the electroless copper plating film or blisters on the resin substrate. As a result, the same problems as those in Comparative Examples 1 to 4 occurred.

[0129] Comparative Example 7 is an example using an electroless copper plating solution that does not contain tertiary alkanolamine, nickel compounds, or nitrogen-containing aromatic compounds. On the resin substrate, there were unprecipitated portions or blisters of the electroless copper plating film, and the formed electroplated copper film lacked surface gloss. Consequently, in addition to the same problems as in Comparative Examples 1 to 4, pit-like defects occurred in the electroplated copper film.

[0130] The flexible substrates of Comparative Examples 1 to 7 have defects in the electroless copper plating film and / or the electroplated copper plating film, which cause defects such as wiring patterns. Therefore, it is not possible to manufacture a reliable flexible wiring substrate. Explanation of the symbols

[0131] 1: Suji entry 2: Rolled copper foil 3: Electroless copper plating film 4: Electroplated copper film 5: Resist layer

Claims

Claim 1 A method for manufacturing a flexible substrate having a resin substrate and a rolled copper foil formed on a part of the resin substrate, wherein an electroless copper plating film and an electroplated copper plating film are laminated thereon. The manufacturing method comprises a process of forming the electroless copper plating film on the resin substrate and the rolled copper foil by performing an electroless copper plating treatment, and a process of forming the electroplated copper plating film on the electroless copper plating film by performing an electroplated copper plating treatment. The electroless copper plating treatment uses an electroless copper plating solution containing a copper compound, a reducing agent, a tertiary alkanolamine, a nickel compound, and a nitrogen-containing aromatic compound. Claim 2 A method for manufacturing a flexible substrate according to claim 1, wherein the concentration of the tertiary alkanolamine in the electroless copper plating solution is 0.001 g / L to 1000 g / L, the concentration of the nickel compound is 0.0005 g / L to 5 g / L as a nickel concentration, and the concentration of the nitrogen-containing aromatic compound is 0.00001 g / L to 2 g / L. Claim 3 A method for manufacturing a flexible substrate according to claim 1 or 2, wherein the tertiary alkanolamine is at least one selected from the group consisting of triethanolamine and triisopropanolamine. Claim 4 A method for manufacturing a flexible substrate according to claim 1 or 2, wherein the nitrogen-containing aromatic compound is at least one selected from the group consisting of bipyridines and phenanthrolines.

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