Electroless nickel plating bath and electroless nickel alloy plating bath

Abstract

To provide an electroless nickel (alloy) plating bath capable of achieving excellent formation of a plating film and excellent continuous use of the plating bath without substantially including a nitrogen compound, such as ammonia being a material to be controlled.SOLUTION: An electroless nickel plating bath includes one kind or two or more kinds selected from a group consisting of water-soluble nickel salt, reducer, phenolsulfonic acid, phenolsulfonic acid salt and these hydrates, and an electroless nickel alloy plating bath further includes alloying metal salt in the electroless nickel plating bath.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an electroless nickel plating bath and an electroless nickel alloy plating bath (hereinafter abbreviated as "electroless nickel (alloy) plating bath") that do not contain elements that have a large environmental load, such as nitrogen, and that have a low environmental load. More specifically, the present invention relates to an electroless nickel plating bath and an electroless nickel alloy plating bath that are excellent in stability and plating deposition rate. [Background technology]

[0002] Electroless plating is a technique for obtaining a metal film by reducing metal ions in a solution containing metal ions and a reducing agent through a chemical reaction. Among these, electroless nickel plating and electroless nickel alloy plating (hereinafter collectively referred to as "electroless nickel (alloy) plating") are used for a variety of purposes, including electrical conductivity treatment when plating plastics, rust prevention, hardness improvement, solderability improvement, and solder wettability improvement. They are widely used industrially for underplating of decorative parts such as automobile parts and plumbing fixtures, underplating of printed circuit boards and ITO substrates, resistors, magnetic disks, electromagnetic wave shielding, and the like. They are also used as a metal matrix for obtaining composite plating films in which fine particles such as polytetrafluoroethylene are uniformly dispersed in the metal film (Patent Document 1).

[0003] Ammonia has traditionally been added to electroless nickel (alloy) plating solutions, particularly those used for plating on plastics, to improve the performance of the plating bath. The presence of ammonia suppresses the random reduction of nickel ions at the temperature and pH required for the reduction of nickel ions to metal, a reaction commonly known as autolysis, and also ensures a good deposition rate for the electroless plating film, enabling good production of nickel (alloy) plating films and good continuous use of the plating bath.

[0004] Meanwhile, the environmental impact of ammonia emissions has long been recognized, and in recent years, with growing environmental awareness, strict wastewater regulations have been established, particularly in China. These regulations include not only restrictions on ammonia, which has traditionally been used in electroless plating baths, but also restrictions on nitrogen (Non-Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-257460 [Non-patent literature]

[0006] [Non-Patent Document 1] Petrochemical Industry Pollutant Emission Standards, GB 31571-2015 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in view of the above technical background, and an object of the present invention is to provide an electroless nickel (alloy) plating bath that is substantially free of nitrogen compounds such as ammonia, which are regulated substances, and that can achieve good production of plating films and good continuous use of the plating bath. [Means for solving the problem]

[0008] As a result of extensive research into solving the above problems, the present inventors discovered that the problems could be solved by adding a specific compound to an electroless nickel plating bath, and thus completed the present invention.

[0009] That is, the present invention is an electroless nickel plating bath characterized by containing a water-soluble nickel salt, a reducing agent, and one or more members selected from the group consisting of phenolsulfonic acid, phenolsulfonates, and hydrates thereof.

[0010] The present invention also provides an electroless nickel plating method, which comprises treating an object to be plated in the electroless nickel plating bath.

[0011] Furthermore, the present invention provides an electroless nickel alloy plating bath characterized in that the electroless nickel plating bath further contains an alloying metal salt.

[0012] Furthermore, the present invention provides a method for electroless nickel alloy plating, which comprises treating an object to be plated with the above-mentioned electroless nickel alloy plating bath. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide an electroless nickel (alloy) plating bath that is excellent in plating film appearance, plating deposition rate, and plating bath stability, even without substantially containing regulated nitrogen compounds such as ammonia. Furthermore, since the above performance is not likely to deteriorate even during continuous use of the plating bath, the plating bath can be replaced less frequently, thereby improving work efficiency. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention relates to an electroless nickel plating bath containing one or more members selected from the group consisting of a water-soluble nickel salt, a reducing agent, phenolsulfonic acid, and phenolsulfonate salts and phenolsulfonate hydrates, and to an electroless nickel alloy plating bath obtained by further adding an alloying metal salt to the electroless nickel plating bath.

[0015] The water-soluble nickel salt used in the electroless nickel (alloy) plating bath of the present invention is not particularly limited, and examples thereof include commonly used water-soluble nickel salts, such as nickel sulfate, nickel chloride, nickel acetate, nickel nitrate, nickel hypophosphite, etc. These water-soluble nickel salts may be used alone or in combination.

[0016] The content of these water-soluble nickel salts in the electroless nickel (alloy) plating bath is not particularly limited, but for example, the nickel ion concentration is preferably 0.1 g / L to 100 g / L, and particularly preferably 1 g / L to 50 g / L. If it is less than 0.1 g / L, it may not react, and if it is more than 100 g / L, it may decompose due to overreaction.

[0017] The reducing agent used in the electroless nickel (alloy) plating bath of the present invention is not particularly limited, and examples thereof include commonly used reducing agents such as hypophosphorous acid (salts) such as hypophosphorous acid, sodium hypophosphite, and potassium hypophosphite, and sodium borohydride. One or more of these reducing agents can be used. The electroless nickel (alloy) plating bath of the present invention can also contain commonly used reducing agents such as amine boranes such as dimethylamine borane and trimethylamine borane, and hydrazines (salts) such as hydrazine. However, in order to make the electroless nickel (alloy) plating bath nitrogen-free, it is preferable not to use these reducing agents.

[0018] The content of these reducing agents in the electroless nickel (alloy) plating bath varies depending on the type of reducing agent used and the required deposition rate, but for example, 1 g / L to 100 g / L is preferable, and 2 g / L to 50 g / L is particularly preferable. If it is less than 1 g / L, it may not react, and if it is more than 100 g / L, If it is more than / L, decomposition due to overreaction may occur.

[0019] Examples of phenolsulfonic acid, phenolsulfonate salts, and hydrates thereof (hereinafter, these may be referred to as "phenolsulfonic acids") used in the electroless nickel (alloy) plating bath of the present invention include phenolsulfonic acid, phenolsulfonic acid hydrate, sodium phenolsulfonate, potassium phenolsulfonate, lithium phenolsulfonate, zinc phenolsulfonate, tin phenolsulfonate, copper phenolsulfonate, nickel phenolsulfonate, and other phenolsulfonate salts, as well as hydrates of the aforementioned phenolsulfonates. These phenolsulfonic acids, phenolsulfonate salts, and hydrates thereof may be used alone or in combination. Phenolsulfonic acid exists as ortho (o), meta (m), and para (p) isomers, with the para (p) isomer being preferred.

[0020] The content of the phenolsulfonic acid, phenolsulfonate salts, and hydrates thereof in the electroless nickel (alloy) plating bath is not particularly limited, but is preferably 1 g / L to 50 g / L, more preferably 2 g / L to 30 g / L, and particularly preferably 3 g / L to 20 g / L. From the viewpoint of deposition rate, the content of the phenolsulfonic acid, phenolsulfonate salts, and hydrates thereof in the electroless nickel (alloy) plating bath is preferably 7.5 g / L to 20 g / L, and particularly preferably 12.5 g / L to 17.5 g / L. If the content is less than 1 g / L, the effect of improving plating deposition may not be sufficient, and if the content is more than 50 g / L, decomposition due to overreaction may occur.

[0021] When the electroless nickel (alloy) plating bath of the present invention is an electroless nickel alloy plating bath, it is necessary to further contain a known alloying metal salt. This alloying metal salt improves the physical properties of the plating film, such as hardness, magnetism, ductility, electrical resistance, and toughness. The metal of such an alloying metal salt is not particularly limited, but examples include iron, copper, tin, cobalt, tungsten, rhenium, manganese, palladium, vanadium, zinc, chromium, gold, silver, and platinum. These metals of the alloying metal salt can be used alone or in combination.

[0022] The content of the alloying metal salt in the electroless nickel alloy plating bath is not particularly limited, but is preferably 0.1 g / L to 100 g / L, and particularly preferably 1 g / L to 50 g / L, as the alloying metal salt, for example.

[0023] In addition to the above-mentioned essential components, the electroless nickel (alloy) plating bath of the present invention preferably contains a complexing agent. The complexing agent is not particularly limited, but various inorganic and organic acids are preferably used. Specific examples of inorganic and organic acids include boron compounds such as boric acid and borax; monocarboxylic acid compounds, dicarboxylic acid compounds, or hydroxycarboxylic acid compounds, such as acetic acid, propionic acid, malic acid, lactic acid, succinic acid, malonic acid, adipic acid, citric acid, fumaric acid, maleic acid, gluconic acid, glycolic acid, benzoic acid, and hydroxybenzoic acid, and salts thereof. These complexing agents may be used alone or in combination. Among these complexing agents, citric acid, malic acid, succinic acid, malonic acid, fumaric acid, maleic acid, and hydroxybenzoic acid are preferred, with citric acid, maleic acid, fumaric acid, and hydroxybenzoic acid being more preferred.

[0024] The content of the complexing agent in the electroless nickel (alloy) plating bath is not particularly limited as long as it does not impair the effects of the present invention, but for example, 1 g / L to 100 g / L is preferable, and 10 g / L to 50 g / L is particularly preferable. If it is less than 1 g / L, self-decomposition or nickel hydroxide may occur. On the other hand, if it is more than 100 g / L, it may remain unreacted or a sufficient reaction rate may not be obtained.

[0025] The electroless nickel (alloy) plating bath of the present invention may further contain a stabilizer. The stabilizer is not particularly limited, but examples thereof include bismuth, molybdenum, and antimony. Examples of bismuth include bismuth oxide and bismuth sulfate. Examples of molybdenum include molybdates such as sodium molybdate, potassium molybdate, and ammonium molybdate; hydrates of the above molybdates such as disodium molybdate dihydrate; and molybdic acid. Examples of antimony include antimonates such as sodium antimonate, potassium antimonate, and ammonium antimonate; hydrates of these antimonates; antimonic acid; antimonyl-L-tartaric acid; and potassium antimonyl tartrate. These stabilizers may be used singly or in combination.

[0026] The content of the stabilizer in the electroless nickel (alloy) plating bath is not particularly limited as long as it is within a range that does not impair the effects of the present invention. For example, the content of bismuth, calculated as bismuth metal, is 0.1 mg / L to 1 g / L, preferably 0.5 mg / L to 200 mg / L; the content of molybdenum, calculated as molybdenum metal, is 0.1 mg / L to 1 g / L, preferably 10 mg / L to 500 mg / L; and the content of antimony, calculated as antimony metal, is 0.1 mg / L to 1 g / L, preferably 0.5 mg / L to 200 mg / L.

[0027] The electroless nickel (alloy) plating bath of the present invention may further contain a reaction accelerator / stress reducer. The reaction accelerator / stress reducer is not particularly limited, but examples include organic sulfur compounds and inorganic sulfur compounds. Specific examples include thiosulfates, thionates, polythionates, thioureas, thiocyanates, thiosulfonates, thiocarbonates, thiocarbamates, thiosemicarbazides, sulfides, disulfides, thiols, mercaptans, thioglycolic acid, thiodiglycolic acid, and derivatives thereof. These reaction accelerators / stress reducers may be used singly or in combination.

[0028] The content of the reaction accelerator / stress reducer in the electroless nickel (alloy) plating bath is not particularly limited as long as it is within a range that does not impair the effects of the present invention, but is, for example, 0.001 mg / L to 1000 mg / L, preferably 0.01 mg / L to 100 mg / L.

[0029] The electroless nickel (alloy) plating bath of the present invention can further contain a film property improver. The film property improver is not particularly limited, but examples thereof include fluororesins or fluorinated compounds such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and fluorinated pitch; organic polymers such as nylon and polyethylene; inorganic materials such as graphite, graphite fluoride, molybdenum disulfide, silicon carbide, titanium oxide, and diamond; and water-insoluble fine particles and short fibers generally used in electroless composite plating baths, such as carbon nanotubes, which can be used alone or in combination.

[0030] The content of the film property improver in the electroless nickel (alloy) plating bath is not particularly limited as long as it does not impair the effects of the present invention, but is preferably 0 to 500 g / L, and particularly preferably 1 g / L to 10 g / L. If the content exceeds 500 g / L, good deposition of the plating film may not be achieved, and the film property improver may not be uniformly dispersed in the film.

[0031] The pH of the electroless nickel (alloy) plating bath of the present invention is not particularly limited, but is preferably adjusted to a pH of 3 to 11 during plating, and more preferably to a pH of 4 to 10. By adjusting the pH of the electroless plating bath within this range, an efficient reduction reaction of metal ions proceeds, resulting in an improved deposition rate of the electroless plated film. The pH of the plating bath can be adjusted by using an acid such as hydrochloric acid or sulfuric acid, or an alkali such as sodium hydroxide, potassium hydroxide, or lithium hydroxide. The solution can be added as needed, preferably diluted with water.

[0032] In the present invention, it is preferable not to adjust the pH with nitrogen-containing compounds such as ammonia. It is also preferable not to use nitrogen-containing amine boranes as reducing agents or other components. This makes the electroless nickel (alloy) plating bath of the present invention substantially free of nitrogen (nitrogen-free). Here, "substantially free" means that the total nitrogen analysis (JIS K0102 45.1) is 5 ppm or less, taking into account ammonia and other elements in the atmosphere.

[0033] Furthermore, the electroless nickel (alloy) plating bath of the present invention can be prepared without using mercury, arsenic, cadmium, or lead, and therefore is substantially free of mercury, arsenic, cadmium, or lead (restricted substance-free). The electroless nickel (alloy) plating bath of the present invention is unlikely to have any adverse effect on the environment or human body, and is not subject to regulations, guidelines, etc. Here, "substantially free" means that the concentration is 0.1 ppm or less when measured by ICP-MS or the like.

[0034] A preferred embodiment of the electroless nickel (alloy) plating bath of the present invention has the following composition: In both plating baths, the pH is not adjusted with nitrogen-containing substances such as ammonia, nitrogen-containing amine boranes are not intentionally used in reducing agents or other components, and compounds containing mercury, arsenic, cadmium, or lead are not intentionally added.

[0035] <Electroless nickel plating bath> Water-soluble nickel salt 0.1g / L~100g / L Reducing agent 1g / L~100g / L Phenolsulfonic acids 1g / L~50g / L (Optional) Complexing agent 1g / L~100g / L (Optional) Stabilizer 0.1mg / L~1g / L (Optional) Reaction accelerator / stress reducer 0.001mg / L~1000mg / L pH 3 to 11

[0036] <Electroless nickel alloy plating bath> Water-soluble nickel salt 0.1g / L~100g / L Reducing agent 1g / L~100g / L Phenolsulfonic acids 1g / L~50g / L Alloying metal salts 0.1g / L~100g / L (Optional) Complexing agent 1g / L~100g / L (Optional) Stabilizer 0.1mg / L~1g / L (Optional) Reaction accelerator / stress reducer 0.001mg / L~1000mg / L pH 3 to 11

[0037] The electroless nickel (alloy) plating bath of the present invention can be prepared by mixing and dissolving the above components.

[0038] Furthermore, the temperature of the electroless nickel (alloy) plating bath of the present invention during plating is not particularly limited as long as it is a temperature at which the reduction reaction of nickel ions occurs, but in order to cause an efficient reduction reaction, a temperature of 15 to 98°C is preferred, and a temperature of 25 to 60°C is particularly preferred.

[0039] The plating method using the electroless nickel (alloy) plating bath of the present invention obtained as described above may be the same as a plating method using a normal electroless plating bath, and is not particularly limited. For example, the object to be plated may be treated with the electroless nickel (alloy) plating bath of the present invention. Furthermore, before treatment with the electroless nickel (alloy) plating bath of the present invention, it is preferable to degrease the object to be plated, rinse with water, add a catalyst, activate the catalyst, etc. The method for treating the object to be plated with the electroless nickel (alloy) plating bath of the present invention is not particularly limited, but examples include a method of immersing the object to be plated in a prepared electroless nickel (alloy) plating bath of the present invention, and a method of spraying the prepared electroless nickel (alloy) plating bath of the present invention onto the object to be plated.

[0040] There are no particular limitations on the substrates that can be plated with the electroless nickel (alloy) plating bath of the present invention, as long as they can be plated with electroless nickel. Examples include resins such as acrylonitrile-butadiene-styrene copolymer (ABS), acrylonitrile-styrene copolymer (AS), polycarbonate (PC), PC / ABS, polypropylene (PP), polyamide (PA), and carbon fiber reinforced plastic (CFRP).

[0041] Furthermore, when plating is performed using the electroless nickel (alloy) plating bath of the present invention, as the plating progresses, metal ions are reduced to metal by the reducing agent, resulting in a decrease in the metal ion concentration and reducing agent concentration in the plating solution, as well as a decrease in pH. Therefore, it is preferable to continuously or at appropriate intervals replenish the electroless nickel (alloy) plating bath with water-soluble nickel salts, reducing agents, complexing agents, p-phenolsulfonate salts, stabilizers, pH adjusters, etc. to restore their original concentrations. It is also preferable to measure the metal ion concentration, reducing agent concentration, and pH in the plating solution continuously or at appropriate intervals and replenish them depending on the measurement results.

[0042] The electroless nickel (alloy) plating of the present invention can produce electroless nickel-plated products and electroless nickel alloy plating. These plated products differ from conventional plated products in the phosphorus content of the film. Conventional plated films have a phosphorus content of approximately 1 to 5 wt%, while the plated film of the present invention has a phosphorus content of 7 to 12 wt%. Furthermore, the plated film of the present invention has the physical property of being less soluble in nitric acid than conventional plated films. These plated products can be used in a wide range of applications, including underplating for decorative parts such as automobile parts and plumbing fixtures, underplating for printed circuit boards and ITO substrates, resistors, magnetic disks, electromagnetic wave shielding, and the metal matrix of composite plated films containing fine particles. [Example]

[0043] Next, the present invention will be further explained by way of examples, but the present invention is not limited to these examples.

[0044] Example 1 Electroless Nickel Plating: An ABS resin test piece (size: 2 mm x 60 mm x 80 mm) was degreased by immersion in a degreasing solution (EBAPREP SK-144, manufactured by JCU Corporation) at 50°C for 5 minutes. The test piece was then etched by immersion in an aqueous solution containing 380 g / L CrO3 and 380 g / L concentrated sulfuric acid heated to 68°C for 10 minutes. After rinsing with water, the test piece was neutralized at room temperature for 1 minute using an ENILEX RD (manufactured by JCU Corporation). After neutralization, the test piece was rinsed with water, immersed in 80 mL / L hydrochloric acid at room temperature for approximately 15 seconds, and then immersed in a catalyzed solution (ENILEX CT-806, manufactured by JCU Corporation) at 35°C for 3 minutes. The test piece was then rinsed with water and immersed in an 80 mL / L hydrochloric acid solution at 35°C for 3 minutes to activate the catalyst, after which it was rinsed again with water. Finally, the test piece was immersed in an electroless nickel plating bath for electroless nickel plating.

[0045] [Evaluation of the initial performance of electroless nickel plating bath] An electroless nickel plating bath containing p-phenolsulfonate according to the present invention was prepared in accordance with a conventional method using the following composition. For comparison, a bath containing no p-phenolsulfonate and a bath containing ammonia were also used.

[0046] <Electroless nickel plating bath composition (nitrogen-free, restricted substance-free)> Nickel sulfate hexahydrate 22g / L Sodium hypophosphite monohydrate 18g / L Bismuth oxide 6mg / L complexing agent * Appropriately Sodium p-phenolsulfonate dihydrate Amount listed in Table 1 pH of plating solution ** 8.8 Ammonia Amount listed in Table 1 Sodium hydroxide as needed * The complexing agent was a combination of two or more of citric acid, malic acid, succinic acid, malonic acid, fumaric acid, maleic acid, hydroxybenzoic acid, and their salts, and was added so that the total amount of complexing agent was 50g / L or less. **The plating baths (1) to (3) of the present invention and the comparative bath (1) were prepared with sodium hydroxide, and the comparative bath (2) was prepared with ammonia.

[0047] [Table 1]

[0048] <Plating conditions> Bath temperature 42℃ Mixing Stirrer mixing Plating time: 7 minutes

[0049] The deposition rate of the obtained electroless nickel plating film was measured using a fluorescent X-ray film thickness meter. The results are shown in Table 2.

[0050] [Table 2]

[0051] The results in Table 2 demonstrate that the plating bath of the present invention containing sodium p-phenolsulfonate dihydrate achieves a deposition rate sufficient for practical use. In particular, it was confirmed that by incorporating a large amount of sodium p-phenolsulfonate dihydrate, a deposition rate equivalent to that of a plating bath containing ammonia can be achieved. Furthermore, the plating bath of the present invention does not have the irritating odor characteristic of ammonia and is easy to use.

[0052] Example 2 Phosphorus content of electroless nickel plating film: After electroless plating was performed by the method described in Example 1, the coating was dissolved using 35% nitric acid, and the nickel concentration and phosphorus concentration in the resulting solution were measured by ICP emission spectrometry to evaluate the phosphorus content.

[0053] A film with a phosphorus content of 8.9 wt% was obtained from the plating bath (2) of the present invention. A film with a phosphorus content of 3.8 wt% was obtained from the comparative bath (2). Furthermore, the film obtained from the plating bath (2) of the present invention was less soluble in nitric acid than the film obtained from the comparative bath (2).

[0054] Example 3 Continuous use test of electroless nickel plating bath: A continuous use test was carried out on the plating bath (2) of the present invention, which was confirmed to have excellent plating deposition properties from the results in Table 2. In the continuous use test, the electroless nickel plating bath was used continuously for 1, 2, and 3 turns to carry out electroless plating, and the results were evaluated under the following criteria.

[0055] <Relative deposition rate> The deposition rate during continuous use for each turn was measured in the same manner as in Example 1, and the measured values ​​were used to evaluate the rate of decrease in deposition rate during each turn relative to the initial deposition rate obtained in Example 1 using the following criteria.

[0056] Judgment Deposition rate ◎: Decreased by 0% to 10% ○: Decreased by 10% to 20% △: Decreased by 20% to 25% ×: Decreased by 25% or more

[0057] The stability of the plating bath was evaluated using the following criteria. <Method for evaluating plating bath stability> After plating was completed, the deposits on the bottom of the plating tank were visually inspected.

[0058] Judgment Visual confirmation of precipitates ◎: No precipitates ○: Precipitates with a diameter of 5 mm or less were confirmed △: Precipitates with a diameter of 5 mm or more were observed ×: The plating bath decomposed by itself

[0059] Here, "one continuous turn" refers to plating continuously until an amount of nickel metal equivalent to the initial nickel ion concentration in the electroless nickel plating bath is plated. For example, if the initial nickel ion concentration in the electroless nickel plating bath is M [g / L], one turn is the point at which M [g / L] of nickel is deposited by plating. Therefore, in this case, "three continuous turns" refers to plating continuously until 3 x M [g / L] of nickel is plated.

[0060] [Table 3]

[0061] The plating bath (2) of the present invention evaluated in Example 3 was able to perform electroless nickel plating well for up to three turns, and even when used continuously, there was little decrease in the deposition rate and the bath stability was excellent. Furthermore, no undeposited plating was observed.

[0062] Furthermore, the plating bath (2) of the present invention was superior to the comparative plating bath (2) using ammonia in that the decrease in deposition rate during turning was minimal. Furthermore, in terms of plating bath stability, the formation of precipitates in the plating bath was minimal, confirming its performance comparable to that of a bath using ammonia. Furthermore, the plating bath of the present invention was found to have no irritating odor characteristic of ammonia and to be easy to use.

[0063] Example 4 Electroless Nickel Plating: An electroless nickel plating bath of the present invention containing p-phenolsulfonate was prepared in the following composition according to a conventional method.

[0064] <Electroless nickel plating bath composition (nitrogen-free, restricted substance-free)> Nickel sulfate hexahydrate 20g / L Sodium hypophosphite monohydrate 20g / L Bismuth oxide 4.8mg / L complexing agent * Appropriately Sodium p-phenolsulfonate dihydrate 10g / L Thiodiglycolic acid 95mg / L Plating solution pH (adjusted with sodium hydroxide) 8.6 * The complexing agent was a combination of two or more of citric acid, malic acid, succinic acid, malonic acid, gluconic acid, glycolic acid, hydroxybenzoic acid, and their salts, and was added so that the total amount of complexing agent was 50g / L or less.

[0065] The electroless nickel plating bath of the present invention can be used to carry out electroless nickel plating in the same manner as in Examples 1 and 3.

[0066] Example 5 Electroless Nickel Plating: An electroless nickel plating bath of the present invention containing p-phenolsulfonate was prepared in the following composition according to a conventional method.

[0067] <Electroless nickel plating bath composition (nitrogen-free, restricted substance-free)> Nickel sulfate hexahydrate 24g / L Sodium hypophosphite monohydrate 20g / L Disodium molybdate dihydrate 126 mg / L complexing agent * Appropriately Sodium p-phenolsulfonate dihydrate 20g / L Plating solution pH (adjusted with sodium hydroxide) 9.2 * The complexing agent was a combination of two or more of citric acid, succinic acid, acetic acid, lactic acid, malonic acid, hydroxybenzoic acid, and their salts, and was added so that the total amount of complexing agent was 50g / L or less.

[0068] The electroless nickel plating bath of the present invention can be used to carry out electroless nickel plating in the same manner as in Examples 1 and 3.

[0069] Example 6 Electroless nickel alloy plating: An electroless nickel alloy plating bath of the present invention containing p-phenolsulfonate was prepared in the following composition according to a conventional method.

[0070] <Electroless nickel alloy plating bath composition (nitrogen-free, restricted substance-free)> Nickel sulfate hexahydrate 19g / L Copper sulfate pentahydrate 0.75g / L Sodium hypophosphite monohydrate 20g / L Bismuth oxide 3.6mg / L complexing agent * Appropriately Sodium p-phenolsulfonate dihydrate 15g / L Plating solution pH (adjusted with sodium hydroxide) 9.4 * The complexing agent was a combination of two or more of citric acid, malic acid, succinic acid, malonic acid, fumaric acid, maleic acid, hydroxybenzoic acid, and their salts, and was added so that the total amount of complexing agent was 50g / L or less.

[0071] The electroless nickel alloy plating bath of the present invention can be used to carry out electroless nickel alloy plating in the same manner as in Examples 1 and 3. [Industrial Applicability]

[0072] The electroless nickel (alloy) plating bath of the present invention can be used for electroless nickel (alloy) plating. That's all

Claims

1. An electroless nickel plating bath comprising a water-soluble nickel salt, a reducing agent, and one or more members selected from the group consisting of phenolsulfonic acid, phenolsulfonates, and hydrates thereof.

2. 2. The electroless nickel plating bath according to claim 1, further comprising a complexing agent.

3. 3. The electroless nickel plating bath according to claim 1, comprising 1 g / L to 50 g / L of one or more members selected from the group consisting of phenolsulfonic acid, phenolsulfonates, and hydrates thereof.

4. 4. The electroless nickel plating bath according to claim 1, wherein the phenolsulfonate is one or more salts selected from the group consisting of sodium phenolsulfonate, potassium phenolsulfonate, lithium phenolsulfonate, zinc phenolsulfonate, tin phenolsulfonate, copper phenolsulfonate, and nickel phenolsulfonate.

5. 5. The electroless nickel plating bath according to claim 1, which is substantially free of nitrogen.

6. 6. The electroless nickel plating bath according to claim 1, which is substantially free of mercury, arsenic, cadmium, or lead.

7. 7. An electroless nickel alloy plating bath comprising the electroless nickel plating bath according to claim 1, further containing an alloying metal salt.

8. 7. The electroless nickel alloy plating bath according to claim 6, wherein the metal of the alloying metal salt is one or more metals selected from the group consisting of iron, copper, tin, cobalt, tungsten, rhenium, manganese, palladium, vanadium, zinc, chromium, gold, silver, and platinum.

9. An electroless nickel plating method comprising treating an object to be plated with the electroless nickel plating bath according to any one of claims 1 to 6.

10. 9. An electroless nickel alloy plating method comprising treating an object to be plated with the electroless nickel alloy plating bath according to claim 7 or 8.

11. An electroless nickel-plated product obtained by treating an object to be plated with the electroless nickel plating bath according to any one of claims 1 to 6.

12. 9. An electroless nickel alloy plated product obtained by treating an object to be plated with the electroless nickel alloy plating bath according to claim 7 or 8.

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