Manufacturing method for flexible substrate

Abstract

To provide a method of manufacturing a flexible substrate capable of suppressing non-deposition of an electroless copper plating film and a blister as well as suppressing a pit-shaped defect of an electrolytic copper plating film.SOLUTION: The present invention discloses a method of manufacturing a flexible substrate in which an electroless copper plating film and an electrolytic copper plating film are laminated on a resin substrate and a rolled copper foil formed on a part of the resin substrate. The manufacturing method has the steps of: forming the electroless copper plating film on the resin substrate and the rolled copper foil by performing an electroless copper plating treatment; and forming the electrolytic copper plating film on the electroless copper plating film by performing the electrolytic copper plating treatment. The electroless copper plating treatment uses an electroless copper plating liquid containing a copper compound, a reducer, a tertiary alkanolamine, a nickel compound, and an aromatic compound including nitrogen.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Flexible wiring boards have flexibility and allow three-dimensional wiring and movable wiring within electronic devices, and are therefore used in various electronic devices such as mobile terminals, liquid crystal televisions, notebook computers, and digital cameras. Flexible wiring boards are produced by forming a wiring pattern on a flexible substrate (precursor) in which a conductive layer is formed on a base material. Flexible substrates are produced by various known methods, and various improvement techniques have been proposed to increase connection reliability.

[0003] For example, Patent Document 1 discloses a bronze plating solution containing a cupric salt, a reducing agent, at least two types of complexing agents, and a stabilizer, and a method for producing a flexible substrate using the plating solution.

[0004] Patent Document 2 discloses an electroless copper plating bath containing a specific phosphine compound as a stabilizer, and a method for producing a flexible substrate using the plating bath.

[0005] Patent Document 3 discloses a flexible substrate in which an electroless copper plating layer is formed on a polyimide substrate having a predetermined surface roughness. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] China Patent Publication No. 108559980 [Patent Document 2] JP 2005-290415 A [Patent Document 3] JP 2012-15448 A Summary of the Invention [Problem to be solved by the invention]

[0007] Electrolytic copper foil and rolled copper foil are used as conductive layers, but rolled copper foil is generally used for flexible wiring boards used in moving parts such as hinges of electronic devices, which require even higher bending and folding resistance. Electrolytic copper foil has a columnar crystal structure developed in the thickness direction, so when it is folded, cracks propagate along the grain boundaries, causing early breakage, whereas rolled copper foil has an isotropic crystal structure, so cracks do not propagate easily and it has high bending resistance reliability. In recent years, flexible substrates have come into use in which a conductive layer is formed on a resin substrate by combining rolled copper foil, electroless copper plating, and electrolytic copper plating. However, the following plating film defects have occurred due to conventional electroless copper plating processes using electroless copper plating solutions. First, when a resin substrate is used (i), even if electroless copper plating is performed in a conventional electroless copper plating solution, plating does not deposit on the resin substrate portion where rolled copper foil is not formed, resulting in the formation of a portion on the resin substrate where an electroless copper plating film cannot be formed. Therefore, even if electrolytic copper plating is performed after electroless copper plating, an electrolytic copper plating film cannot be formed on the non-deposited portion, and the non-deposited portion may cause wiring pattern defects or decrease connection reliability. In addition, ii) the electroless copper plating film formed on the resin substrate may have blisters, i.e., the electroless copper plating film may swell and cause gaps between the resin substrate and the plating film, which may cause the plating film to peel off from the resin substrate or reduce connection reliability.

[0008] The present invention has been made in consideration of the above problems, and its object is to provide a method for manufacturing a flexible substrate which can solve the above problems i and ii. [Means for solving the problem]

[0009] [1] A method for producing a flexible substrate in which an electroless copper plating film and an electrolytic copper plating film are laminated on a resin substrate and a rolled copper foil formed on a part of the resin substrate, comprising: The manufacturing method includes: A step of forming the electroless copper plating film on the resin substrate and the rolled copper foil by performing an electroless copper plating process; a step of forming the electrolytic copper plating film on the electroless copper plating film by performing an electrolytic copper plating process; The electroless copper plating process 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.

[0010] [2] In the electroless copper plating solution The concentration of the tertiary alkanolamine is 0.001 g / L to 1000 g / L. The concentration of the nickel compound is 0.0005 g / L to 5 g / L in terms of nickel concentration, The method for producing a flexible substrate according to the above-mentioned [1], wherein the concentration of the nitrogen-containing aromatic compound is 0.00001 g / L to 2 g / L.

[0011] [3] The method for producing a flexible substrate according to the above [1] or [2], wherein the tertiary alkanolamine is at least one selected from the group consisting of triethanolamine and triisopropanolamine.

[0012] [4] The method for producing a flexible substrate according to any one of the above [1] to [3], wherein the nitrogen-containing aromatic compound is at least one selected from the group consisting of bipyridines and phenanthrolines. Effect of the Invention

[0013] According to the present invention, it is possible to form a good electroless copper plating film in which non-plated areas and blisters are suppressed. Furthermore, according to the present invention, a good electrolytic copper plating film in which pit-like defects are suppressed can be formed. Therefore, according to the manufacturing method of the present invention, it is possible to provide a flexible substrate having a good electroless copper plating film and a good electrolytic copper plating film. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram illustrating the manufacturing process of a flexible substrate according to the present invention. [Diagram 2] FIG. 2 is a schematic explanatory diagram of a manufacturing process for a flexible wiring board using the flexible substrate of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The flexible substrate of the present invention can be produced by sequentially subjecting the rolled copper foil surface of the resin substrate to electroless copper plating and electrolytic copper plating to form an electroless copper plating film and an electrolytic copper plating film. The present invention is characterized in that an electroless copper plating bath having a predetermined composition is used as a means for solving the above-mentioned problems.

[0016] The electroless copper plating solution of the present invention contains 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 has a synergistic effect of the tertiary alkanolamine, the nickel compound, and the nitrogen-containing aromatic compound, 1) Suppression of non-deposition of electroless copper plating film on the substrate surface, 2) Suppression of blistering of electroless copper plating film formed on the substrate surface, and 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. In particular, the above 3) is a finding obtained by the present inventors as a result of repeated investigations into the above conventional problems i) and ii). 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 crystal orientation of the rolled copper foil, the electrolytic copper plating film also has the same crystal orientation, and that such an electrolytic copper plating film has no surface gloss and pit-like defects occur on the surface of the electrolytic copper plating film. Such an electrolytic copper plating film causes pattern defects and circuit defects such as reduced connection reliability. In order to avoid such problems, it is effective to form an electroless copper plating film as described in the above 3). By using the electroless copper plating solution of the present invention, the above-mentioned effects 1 to 3 can be obtained for a substrate. Furthermore, an electroless copper plating film formed by subjecting an electroless copper plating process to an electroless copper plating film formed using the electroless copper plating solution of the present invention has suppressed pit-like defects.

[0017] First, the electroless copper plating solution of the present invention will be described. 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.

[0018] Tertiary alkanolamines Tertiary alkanolamines not only act as complexing agents, but are also particularly effective in the above-mentioned 3) formation on the surface of a rolled copper foil of an electroless copper plating film that does not have the same crystal orientation as the rolled copper foil, and contribute to suppressing pit-like defects in the electrolytic copper plating film formed on the surface of the electroless copper plating film.

[0019] Tertiary alkanolamine is a compound having three or more linear or branched alkanol groups. Tertiary alkanolamine is preferably a compound having an alkanol group having 1 to 18 carbon atoms, more preferably trimethanolamine, triethanolamine, tripropanolamine, triisopropanolamine, tributanolamine, tripentanolamine, trihexanolamine, triheptanolamine, trioctanolamine, trinonanolamine, tridecanolamine, tridodecanolamine, tritetradecanolamine, trihexadecanolamine, and trioctadecanolamine. Tertiary alkanolamine is more preferably triethanolamine or triisopropanolamine. The tertiary alkanolamines can be used alone or in combination of two or more kinds in any desired ratio.

[0020] If the concentration of the tertiary alkanolamine is too low, the effect of adding the tertiary alkanolamine may not be sufficient, whereas if the concentration of the tertiary alkanolamine is too high, the electroless copper plating film may not be uniformly formed (hereinafter, sometimes referred to as film uniformity), as in some cases where the electroless copper plating film is not coated on the substrate or rolled copper foil. 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, still more preferably 0.5 g / L or more, and is preferably 1000 g / L or less, more preferably 600 g / L or less, and even more preferably 200 g / L or less.

[0021] Nickel Compounds The nickel compound particularly contributes to the above-mentioned 2) suppression of blistering of the electroless copper plating film formed on the surface of the substrate. The nickel compound is preferably a water-soluble nickel compound, more preferably nickel sulfate, nickel nitrate, nickel chloride, nickel acetate, nickel citrate, nickel tartrate, nickel gluconate, or the like. The nickel compounds can be used alone or in combination of two or more kinds in any ratio.

[0022] If the concentration of the nickel compound is too low, the effect of adding the nickel compound may not be sufficient, whereas if the concentration of the nickel compound is too high, the uniformity of the coating may not be obtained. The nickel compound concentration 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, and is preferably 5 g / L or less, more preferably 2.5 g / L or less, even more preferably 0.5 g / L or less, in terms of nickel concentration.

[0023] Nitrogen-containing aromatic compounds The nitrogen-containing aromatic compound particularly contributes to the above-mentioned 1) suppression of non-deposition of the electroless copper plating film on the substrate surface. The nitrogen-containing aromatic compound is not particularly limited, but is 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. The nitrogen-containing aromatic compounds can be used alone or in combination of two or more kinds in any ratio.

[0024] 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'-disulfonic acid disodium salt, 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine, 2,2'-bis(5,6-dimethyl-1,2,4-triazine), 6,7 It is preferable that the quinoxaline derivative is at least one selected from the group consisting of 2,3-bis(2-pyridyl)-6,7-dimethylquinoxaline, 2,2'-bipyridyl, 6,7-diethyl-2,3-di(2-pyridyl)-quinoxaline, 1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, and 2,9-diphenyl-1,10-phenanthroline.

[0025] If the concentration of the nitrogen-containing aromatic compound is too low, the effect of adding the compound may not be sufficient, whereas if the concentration of the nitrogen-containing aromatic compound is too high, the coating may not be uniform. The concentration of the nitrogen-containing aromatic compound 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, and is 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.

[0026] copper compound Copper compounds are essential compounds for forming electroless copper plating films. The copper compound is a water-soluble copper salt, and preferred examples thereof include copper sulfate, copper nitrate, copper chloride, copper acetate, copper citrate, copper tartrate, and copper gluconate. The copper compounds can be used alone or in combination of two or more kinds in any desired ratio.

[0027] If the concentration of the copper compound is too low, the deposition rate will be slow and the plating time will be long, while if the concentration of the copper compound is too high, the plating solution will become unstable. The concentration of the copper compound in the electroless copper plating solution is preferably 0.05 g / L or more, more preferably 0.5 g / L or more, and is preferably 30 g / L or less, more preferably 10 g / L or less, in terms of copper concentration.

[0028] Reducing Agent The reducing agent may be any known reducing agent for copper ions in the electroless copper plating solution, and is preferably formaldehyde, paraformaldehyde, glyoxylic acid, glyoxylates, aminoboranes such as dimethylamine borane, alkali metal borohydrides, hydrazine, polysaccharides, sugars such as glucose, hypophosphorous acid, hypophosphites, glycolic acid, glycolate salts, formic acid, formates, etc. The reducing agent can be used alone or in combination of two or more kinds in any ratio.

[0029] The reducing agent may be contained in an amount necessary for reducing copper ions. The reducing agent concentration in the electroless copper plating solution is preferably 0.01 g / L or more, more preferably 0.5 g / L or more, and is preferably 100 g / L or less, more preferably 80 g / L or less, and even more preferably 50 g / L or less.

[0030] The electroless copper plating solution of the present invention may further contain optional additives such as a complexing agent, a surfactant, a pH adjuster, a stabilizer, etc., as necessary.

[0031] Complexing Agent In the present invention, the tertiary alkanolamine also acts as a complexing agent. Therefore, other complexing agents may not be added, but may be added optionally. As the other complexing agents, known complexing agents used in electroless copper plating solutions can be used. The complexing agents are preferably monocarboxylic acids such as acetic acid and formic acid, and their ammonium salts, potassium salts, sodium salts, etc.; dicarboxylic acids such as malonic acid, succinic acid, adipic acid, maleic acid, fumaric acid, and their ammonium salts, potassium salts, sodium salts; hydroxycarboxylic acids such as malic acid, lactic acid, glycolic acid, gluconic acid, and citric acid, and their ammonium salts, potassium salts, sodium salts, etc.; ethylenediaminediacetic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, and their ammonium salts, potassium salts, sodium salts, etc.; aminopolycarboxylic acids such as ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid, and their ammonium salts, potassium salts, sodium salts, etc. The complexing agent can be used alone or in combination of two or more kinds in any ratio.

[0032] The concentration of other complexing agents in the electroless copper plating solution may be at a level that does not impair the effects of the present invention, and is preferably 0.0001 g / L or more, more preferably 0.01 g / L or more, and is preferably 1000 g / L or less, more preferably 500 g / L or less.

[0033] Surfactants In the present invention, a known surfactant used in an electroless copper plating solution can be used. The surfactant can be any of an ionic surfactant, a nonionic surfactant, and an amphoteric surfactant, and can be appropriately selected and used. The surfactants can be used alone or in combination of two or more in any desired ratio.

[0034] The concentration of the surfactant in the electroless copper plating solution is not particularly limited, but is preferably 0.000001 g / L or more, more preferably 0.00001 g / L or more, and is preferably 5 g / L or less, more preferably 2 g / L or less.

[0035] pH adjuster In the present invention, it is preferable to appropriately adjust the pH of the electroless copper plating solution to be within the following range by adding a pH adjuster as necessary. Any known pH adjuster used in electroless copper plating solutions can be used. The pH adjuster is preferably a basic compound, an inorganic acid, or an organic acid, more preferably an inorganic acid such as sulfuric acid, hydrochloric acid, or phosphoric acid, or sodium hydroxide, potassium hydroxide, lithium hydroxide, cesium hydroxide, rubidium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, or butylammonium hydroxide. The pH adjusters can be used alone or in combination of two or more in any desired ratio.

[0036] pH of electroless copper plating solution The pH of the electroless copper plating solution is preferably in the range from acidic to alkaline, more preferably in the range from neutral to alkaline. The pH of the specific electroless copper plating solution is preferably pH 2 or more, more preferably pH 7 or more, and preferably pH 13 or less.

[0037] The method for producing a flexible substrate of the present invention will now be described.

[0038] Resin Substrate The resin substrate 1 is not particularly limited as long as it has 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 preferable. Polyimide-based and PET-based substrates have dimensional stability, little thermal shrinkage, and excellent flexibility.

[0039] Rolled Copper Foil A rolled copper foil 2 is laminated on at least one surface of the resin substrate 1 (FIG. 1(b)). The rolled copper foil may be laminated on both sides of the resin substrate. The rolled copper foil may be laminated on at least a part of the surface of the resin substrate. Various known methods can be adopted for the raw material of the rolled copper foil, the manufacturing method, and the method for laminating the rolled copper foil to the resin substrate. In the present invention, a resin substrate having a commercially available known rolled copper foil can be used. The size and wiring pattern of the rolled copper foil can be appropriately selected according to the required properties. The flexible substrate of the present invention has an electroless copper plating film formed on both the surface of the rolled copper foil and the surface of the substrate. In the present invention, it is preferable to use a flexible substrate having a line and space pattern formed with rolled copper foil. Specific examples include flexible substrates used for flexible displays and FPC connectors.

[0040] Pretreatment process Before electroless copper plating, the resin substrate having the rolled copper foil may be subjected to a suitable pretreatment, if necessary. Examples of the pretreatment include various known steps such as a degreasing step, a conditioning step, a pickling step, a sensitization step (a catalyst application step), and an adhesion promotion step.

[0041] Electroless copper plating In the present invention, an electroless copper plating process is performed to form an electroless copper plating film on the rolled copper foil side of the 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)). The electroless copper plating process uses the electroless copper plating solution of the present invention. In the present invention, the processing conditions are not limited except for the use of the electroless copper plating solution, and known electroless copper plating processing conditions can be adopted.

[0042] The thickness of the electroless copper plating film can be appropriately changed depending on the required properties. The electroless copper plating film is preferably thick enough not to dissolve during the copper electroplating process. The thickness of the electroless copper plating film is preferably 0.01 μm or more, more preferably 0.1 μm or more, and is preferably 5 μm or less, more preferably 2 μm or less.

[0043] Pretreatment process Before carrying out the electrolytic copper plating process, the surface of the electroless copper plating film may be subjected to a suitable pretreatment, if necessary. Examples of the pretreatment include various known steps such as a degreasing step, a conditioning step, and an acid pickling step.

[0044] Copper electroplating process In the present invention, an electrolytic copper plating process is carried out to form an electrolytic copper plating film 4 on the surface of the electroless copper plating film 3 (FIG. 1(d)). The composition of the electrolytic copper plating solution used in the electrolytic copper plating process is not particularly limited. For example, a known electrolytic copper plating solution such as the electrolytic copper plating solution used in the examples can be used. The electrolytic copper plating process conditions are also not limited, and known electrolytic copper plating process conditions can be used.

[0045] The thickness of the electrolytic copper plating film can be appropriately changed depending on the required properties. The thickness of the electrolytic copper plating film may be appropriately adjusted to adjust the thickness of the conductive layer. The thickness of the electrolytic copper plating film is preferably 0.1 μm or more, more preferably 1 μm or more, and is preferably 100 μm or less, more preferably 50 μm or less.

[0046] By the copper electroplating process, a multilayer flexible substrate is obtained in which an electroless copper plating film and an copper electroplating film are laminated in this order on a resin substrate and a rolled copper foil.

[0047] A flexible wiring board can be obtained by forming a wiring pattern on the flexible board of the present invention (FIG. 2(a)) by a known method. For example, a resist layer 5 is provided on an electrolytic copper plating film 4, and the resist layer 5 is patterned into a desired circuit pattern (FIG. 2(b)). The exposed electrolytic copper plating film 4 and its underlying electroless copper plating film 3 are then etched away (FIG. 2(c)). The resist layer 5 is then peeled off to obtain a flexible wiring board (FIG. 2(d)). By using the flexible substrate of the present invention, a flexible wiring substrate free from defects such as chipping or breaking of wiring can be obtained. EXAMPLES

[0048] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples, and can be modified as long as it satisfies the spirit of the invention, and all such modifications are included in the technical scope of the present invention. In the following, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[0049] Experiment 1 A polyimide film (Kapton200EN, Toray DuPont: 50mm x 50mm) was used as the resin substrate. A high-performance rolled copper foil HA-V2 with a line and pattern (JX Metals: 1mm line width x 50mm line length, 1mm space width) was placed on the surface of this polyimide film. This polyimide film was pretreated according to the process shown in Table 1, and then electroless copper plating was performed using electroless copper plating solutions having the compositions shown in Tables 2 to 7 to produce samples in which electroless copper plating films were formed on the resin substrate surface and the rolled copper foil surface. The electroless copper plating films of the samples were evaluated for the following two points. (1) The presence or absence of undeposited areas of the electroless copper plating film was visually confirmed. When there was a portion where the polyimide film was exposed, i.e., when there was a portion where the electroless copper plating film was not deposited, it was rated as "poor", and when there was no undeposited portion, it was rated as "good". (2) The presence or absence of blisters on the electroless copper plating film was visually confirmed. When the electroless copper plating film on the polyimide film had one or more blisters, it was rated as "present", and when there were no blisters, it was rated as "absent".

[0050] Experiment 2 After electroless copper plating was performed in the same manner as in Experiment 1, the electroless copper-plated film was subjected to the pickling cleaner treatment and pickling treatment shown in Table 1, and then an electrolytic copper plating treatment was performed to produce each sample in which an electrolytic copper-plated film was formed on the electroless copper-plated film. The electrolytic copper plating films of the samples were evaluated as follows. (3) The surface of the electrolytic copper plating film of the sample was evaluated for gloss using a scanning electron microscope. If the surface was glossy, it was rated as "present," and if the surface was not glossy, it was rated as "absent."

[0051] [Table 1]

[0052] [Table 2]

[0053] [Table 3]

[0054] [Table 4]

[0055] [Table 5]

[0056] [Table 6]

[0057] [Table 7]

[0058] As can be seen from Tables 2 to 7, in each of the samples of Examples 1 to 62 prepared using the electroless copper plating solution of the present invention, the electroless copper plating film on the resin substrate was free of (1) undeposited areas and (2) blisters, and a good electroless copper plating film could be formed. In addition, the electrolytic copper plating film formed on the electroless copper plating film had (3) a gloss, and the flexible substrate of the present invention was free of defects such as pits. Therefore, by using the flexible substrate obtained by the manufacturing method of the present invention, a flexible wiring substrate having high reliability can be manufactured.

[0059] Comparative Examples 1 and 2 are examples in which an electroless copper plating solution not containing a nitrogen-containing aromatic compound was used, and there were areas on the resin substrate where the electroless copper plating film was not deposited, so that an electrolytic copper plating film could not be formed on the undeposited areas.

[0060] Comparative Examples 3 and 4 were examples in which an electroless copper plating solution not containing a nickel compound was used, and blisters were generated in the electroless copper plating film on the resin substrate, resulting in poor adhesion of the electroless copper plating film in the blistered areas to the substrate, and the smoothness of the electroless copper plating film formed in the blistered areas being reduced.

[0061] Comparative Examples 5 and 6 are examples in which electroless copper plating solutions not containing nickel compounds and nitrogen-containing aromatic compounds were used, and there were non-deposited areas and blisters of the electroless copper plating film on the resin substrate, resulting in the same problems as those in Comparative Examples 1 to 4.

[0062] Comparative Example 7 is an example in which an electroless copper plating solution not containing a tertiary alkanolamine, a nickel compound, or a nitrogen-containing aromatic compound was used, and there were non-deposited areas and blisters in the electroless copper plating film on the resin substrate, and the surface of the formed electrolytic copper plating film had no gloss. Therefore, in addition to the same problems as in Comparative Examples 1 to 4, pit-like defects and the like were generated in the electrolytic copper plating film.

[0063] The flexible boards of Comparative Examples 1 to 7 have defects in the electroless copper plating film and / or the electrolytic copper plating film, which cause defects in the wiring patterns, etc. Therefore, it is impossible to manufacture a reliable flexible wiring board. [Explanation of symbols]

[0064] 1 Resin substrate 2. Rolled copper foil 3. Electroless copper plating 4. Electrolytic copper plating 5 Resist layer

Claims

1. A method for producing a flexible substrate in which an electroless copper plating film and an electrolytic copper plating film are laminated on a resin substrate and a rolled copper foil formed on a part of the resin substrate, the method comprising the steps of: The manufacturing method includes: A step of performing an electroless copper plating process to form the electroless copper plating film on the resin substrate and the rolled copper foil; a step of performing an electrolytic copper plating process to form the electrolytic copper plating film on the electroless copper plating film, The electroless copper plating process 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.

2. In the electroless copper plating solution The concentration of the tertiary alkanolamine is 0.001 g / L to 1000 g / L, The concentration of the nickel compound is 0.0005 g / L to 5 g / L in terms of nickel concentration, The method for manufacturing a flexible substrate according to claim 1, wherein the concentration of the nitrogen-containing aromatic compound is 0.00001 g / L to 2 g / L.

3. 3. The method for producing a flexible substrate according to claim 1, wherein the tertiary alkanolamine is at least one selected from the group consisting of triethanolamine and triisopropanolamine.

4. The method for producing a flexible substrate according to any one of claims 1 to 3, wherein the nitrogen-containing aromatic compound is at least one selected from the group consisting of bipyridines and phenanthrolines.

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