JP4366579B2 - Method for forming black nickel film and electroless nickel-phosphorus plating bath - Google Patents

Description

  The present invention relates to a method for forming a black nickel film and an electroless nickel-phosphorous plating bath used for forming the black nickel film.

  As a black film used for the surface treatment of an optical component or a heat radiating member, a film formed by black chrome plating, black nickel plating or the like is known. Also known is a method of obtaining a black nickel film by oxidizing a nickel-phosphorus alloy formed by electroless plating. For example, JP-B-59-22786 (Patent Document 1), JP-B-64-7153 (Patent Document 2), JP-B-7-42588 (Patent Document 3), JP-A-9-78256 (Patent Document) Document 4) describes a method of forming a black film by oxidizing a nickel alloy film, and Japanese Patent Application Laid-Open No. 61-253381 (Patent Document 5) discloses a method of oxidizing black or zinc alloy film by oxidizing it. A method of forming a chemical film is described. However, the black film obtained by these conventional methods may not be able to stably obtain a good black film, and further improvement is necessary, and it is stable and excellent even when the number of turns increases. There has been a demand for a method for obtaining a black film. In addition, some nickel plating baths for forming a nickel alloy film to be blackened contain amino group-containing compounds, but plating baths containing amino group-containing compounds have problems in wastewater treatment and are economical. Was disadvantageous.

Japanese Patent Publication No.59-22786 Japanese Patent Publication No. 64-7153 Japanese Examined Patent Publication No. 7-42588 JP-A-9-78256 JP 61-253381 A

  The present invention has been made in view of the above circumstances, and a method for forming a black nickel film capable of forming a good black nickel plating film regardless of the number of turns, and an electroless nickel-phosphorus used for forming the black nickel film. An object is to provide a plating bath.

As a result of intensive studies to solve the above problems, the inventor of the present invention contains one or more ions of an acid treatment solution, preferably a metal ion selected from iron, copper, silver, cobalt, manganese and molybdenum. In the case of forming a black nickel film by blackening by a treatment in which the nickel-phosphorus alloy film is brought into contact with an acidic treatment liquid, an electroless nickel-phosphorus plating bath for forming the nickel-phosphorus alloy film is formed of a nickel salt or phosphoric acid. Containing one or more sulfur compounds selected from salts, organic acids and / or salts thereof, thioether compounds, thiocyan compounds, thiocarbonyl compounds, thiol compounds, thiosulfuric acid and thiosulfate , and ammonium ions, In addition, by using an electroless nickel-phosphorous plating bath that does not contain an amino group-containing compound, good black nickel With the resulting film, management of supply and the plating bath is facilitated, stable and good black nickel coating was found that obtained regardless of the turn.

  In particular, if the heat treatment is performed after the treatment with the acidic treatment liquid, the film hardness can be improved without fading the black color, and a film having a high hardness and a good black color can be obtained. The present inventors have found that it is possible to achieve the present invention.

That is, the present invention is a nickel salt, phosphate, organic acid and / or salt thereof, thioether compound, thiocyanate compound, thiocarbonyl compound, thiol compound, thiosulfuric acid and thiosulfate on the object to be plated 1 A nickel-phosphorus alloy film is formed by electroless plating using an electroless nickel-phosphorous plating bath containing seeds or two or more sulfur-based compounds, and ammonium ions and not containing amino group-containing compounds, Next, the nickel-phosphorus alloy film is treated by bringing it into contact with an acidic treatment liquid, and the method for forming a black nickel film is characterized in that the black nickel is blackened by the treatment in which the nickel-phosphorus alloy film is brought into contact with the acidic treatment liquid. Electroless nickel-phosphorus plating for forming the nickel-phosphorus alloy film used for forming the film A is a nickel salt, a phosphate, an organic acid and / or salts thereof, thioether compounds, thiocyanate compounds, thiocarbonyl compounds, thiol compounds, one or more sulfur-based selected from thiosulfate and thiosulfate Disclosed is an electroless nickel-phosphorous plating bath containing a compound and ammonium ions and containing no amino group-containing compound.

  According to the present invention, a film exhibiting a good black color such as a high degree of blackening and no interference color on the surface of the film is obtained, and the obtained film also has adhesion and hardness to an object to be plated. It is good. Furthermore, according to the present invention, a film having a good black color can be obtained regardless of the number of turns, and there is no problem in wastewater treatment, which is economically advantageous.

The present invention will be described in detail below.
The method for forming a black nickel film according to the present invention includes a nickel salt, a phosphate, an organic acid and / or salt thereof, a sulfur compound, and an ammonium ion on the object to be plated, and an amino group-containing compound. A nickel-phosphorus alloy film is formed by electroless plating using an electroless nickel-phosphorus plating bath, and the nickel-phosphorus alloy film is then contacted with an acidic treatment solution for treatment.

  In addition, the electroless nickel-phosphorous plating bath of the present invention forms the nickel-phosphorous alloy film used to form a black nickel film by blackening by a treatment in which the nickel-phosphorous alloy film is brought into contact with an acidic treatment liquid. Electroless nickel-phosphorus plating bath, which contains a nickel salt, phosphate, organic acid and / or salt thereof, a sulfur compound, and ammonium ion, and does not contain an amino group-containing compound.

  The electroless nickel-phosphorous plating bath used to form the nickel-phosphorus alloy film in the present invention contains a nickel salt and a phosphate. As the nickel salt, nickel nitrate, nickel chloride, nickel acetate and the like are preferable, and the concentration in the plating bath is preferably 0.01 to 0.2 mol / L. The phosphate is preferably a hypophosphite such as potassium hypophosphite or sodium hypophosphite, or a phosphite such as potassium phosphite or sodium phosphite. Acid salts are preferred. Moreover, it is preferable that the density | concentration in the plating bath is 0.1-2 mol / L, especially 0.1-1 mol / L.

  The electroless nickel-phosphorous plating bath of the present invention contains an organic acid and / or a salt thereof for the purpose of complexing nickel ions in the plating bath and / or suppressing pH fluctuation. Organic acids and organic acid salts include formic acid, acetic acid, propionic acid, fumaric acid, malonic acid, succinic acid, adipic acid and other carboxylic acids, carboxylic acid salts (sodium salt, potassium salt, ammonium salt, etc.), lactic acid And oxycarboxylic acids such as citric acid, malic acid, glycolic acid, tartaric acid and gluconic acid, and salts of the above oxycarboxylic acids (sodium salt, potassium salt, ammonium salt and the like). These organic acids and / or salts thereof can be contained alone or in combination of two or more. Moreover, it is also possible to use ammonium salt as said organic acid salt as a supply source of ammonium ion mentioned later. The concentration of the organic acid and / or salt thereof in the plating bath is preferably 0.1 to 2 mol / L, particularly preferably 0.1 to 1 mol / L. When the concentration of the organic acid and / or salt thereof is less than 0.1 mol / L, the stability of the plating bath is deteriorated, and the black nickel film may not be stably obtained as the turn proceeds. If it is higher than 2 mol / L, the plating may not proceed.

The electroless nickel-phosphorous plating bath of the present invention contains a sulfur compound. As the sulfur compound, one or more selected from thioether compounds, thiocyan compounds, thiocarbonyl compounds, thiol compounds, thiosulfuric acid and thiosulfate are used . Specifically, thioether compounds include methionine, dimethyl sulfoxide, thiodiglycolic acid, benzothiazole, and thiocyanate compounds include thiocyanic acid, potassium thiocyanate, sodium thiocyanate, ammonium thiocyanate, and the like. Thiourea or derivatives thereof, thiol compounds such as cysteine, thiolactic acid, thioglycolic acid, mercaptoethanol, butanethiol and the like, and thiosulfate include sodium thiosulfate, and the concentration in the plating bath is 0. It is preferable that it is 0001-1g / L.

  Among them, one kind selected from thioether compounds such as methionine, dimethyl sulfoxide, thiodiglycolic acid, benzothiazole, and thiocyanate compounds such as thiocyanic acid and thiocyanate (potassium thiocyanate, sodium thiocyanate, ammonium thiocyanate) Two or more are preferred. By using a thioether compound or a thiocyan compound, a better black nickel film having no interference color can be obtained.

  In the present invention, the electroless nickel-phosphorous plating bath contains ammonium ions. In order to contain ammonium ions in the plating bath, a method of adding aqueous ammonia or ammonium salt can be employed. In this case, aqueous ammonia, ammonium chloride, ammonium hydroxide or the like can be used. It is also possible to contain ammonium ions by using an ammonium salt of an organic acid. In addition, it is preferable that the density | concentration in the plating bath of this ammonium ion is 0.1-10 mol / L.

  By containing ammonium ions in the above range, the electroless nickel-phosphorus plating bath can be configured to contain no generally required amino group-containing compound, and is economical and advantageous for wastewater treatment. can do. In addition, by using ammonium ions, the above-described organic acid and / or organic acid salt, and a sulfur compound in combination, a good black nickel film having no interference color can be obtained regardless of the number of turns. Furthermore, by adding a carboxylic acid and / or salt thereof and an oxycarboxylic acid / or salt as an organic acid, replenishment and management of the plating bath are facilitated, regardless of the type of sulfur compound contained. The phosphorus content in the nickel-phosphorus alloy film to be formed can be stably maintained in an optimum range for obtaining a black nickel film described later.

  The electroless nickel-phosphorous plating bath of the present invention may contain various other known additives such as stabilizers such as Pb and Tl and surfactants as appropriate, but does not contain an amino group-containing compound. It is preferable. Moreover, it is preferable that pH of a plating bath is 5-8, especially 6-7.

  Moreover, the electroless nickel-phosphorus plating bath of the present invention does not contain an amino group-containing compound. When the amino group-containing compound is contained, problems in wastewater treatment occur, which is uneconomical, and interference colors are easily generated. Examples of the amino group-containing compound include primary amines such as monoethanolamine, secondary amines such as dimethylamine, tertiary amines such as TEA (triethanolamine), amino acids such as glycine, and salts thereof. It is done.

  In the present invention, a nickel-phosphorous alloy film is formed on the object to be plated using the electroless nickel-phosphorous plating bath, and then the nickel-phosphorous alloy film is blackened by treating with an acidic treatment liquid. A black nickel film is formed. The nickel-phosphorus alloy film is blackened by treating the nickel-phosphorous alloy film with an acid treatment solution to oxidize the nickel-phosphorus alloy film to nickel oxide. Estimated to be achieved. Therefore, in order to obtain a good black nickel coating, it is necessary to effectively and efficiently cause the coating to blacken, but it is formed by using the above electroless nickel-phosphorous plating bath. The nickel-phosphorus alloy film can be blackened effectively and efficiently by the acidic treatment liquid. In addition, it is preferable that the phosphorus content in a nickel-phosphorus alloy film is 2-7 mass%, especially 3-5 mass%.

  The plating temperature and plating time in the electroless nickel-phosphorous plating bath of the present invention are appropriately determined depending on the composition of the plating bath, the thickness of the nickel-phosphorous alloy film to be formed, and the like, but are not particularly limited. A plating temperature of ˜95 ° C., particularly 70 to 95 ° C., and a plating time of 0.1 to 5 hours can be suitably applied.

  In the present invention, before the nickel-phosphorus alloy film is formed, a nickel-phosphorus alloy is preferably formed after an underlayer having a thickness of preferably 0.1 to 20 μm is formed on the substrate by electroless nickel plating or the like. It is preferable to form a film. By forming the underlayer, it is possible to reduce the influence of roughness of the substrate surface and the like, and the blackened film is preferable because it has more excellent physical properties, particularly excellent black color. Unlike the above-described nickel-phosphorus alloy film formed thereon, this underlayer is not directly treated with an acidic treatment solution, and can be formed by a conventionally known plating method, for example, It can be formed using a conventionally known electroless nickel plating bath.

  Next, this nickel-phosphorus alloy film is treated with an acidic treatment liquid to form a black nickel film. In the present invention, the treatment with the acidic treatment liquid is performed without subjecting the nickel-phosphorus alloy film obtained as described above to heat treatment. Heat treatment of the film is effective in that the film hardness can be improved, but in the conventional method of forming a black film, discoloration occurs when heat treatment is performed after blackening, and the heat-treated film However, there was a problem that sufficient black color could not be obtained even when blackening treatment was performed. On the other hand, the black nickel film obtained by the present invention can improve the film hardness without fading black by the heat treatment after the blackening treatment, as will be described later. Is unnecessary.

  In the present invention, examples of the acidic treatment liquid include one or more aqueous solutions of nitric acid, hydrochloric acid, sulfuric acid, persulfuric acid, and hydrogen peroxide, and the concentration in the acidic treatment liquid is 10 to 800 g / L. It is preferable. The pH of the acidic treatment liquid is preferably 4 or less, particularly 2 or less.

Moreover, in this invention, it is preferable that the said acidic process liquid contains the 1 type (s) or 2 or more types of metal ion chosen from iron, copper, silver, cobalt, manganese, and molybdenum, especially copper and iron. Examples of metal ions include ions composed only of metal elements such as Cu ²⁺ and Fe ³⁺ , and complex ions containing the above metals. In this case, the concentration of the metal ions in the acidic treatment liquid is preferably 0.1 to 10 mol / L.

  By including the metal ions in the acidic treatment liquid, it is possible to advance the blackening of the nickel-phosphorus alloy film by the metal substitution reaction as well as the oxidation reaction in the blackening treatment. The above-described nickel-phosphorus alloy film formed by the electroless nickel-phosphorus plating bath of the present invention is also effective in this metal substitution reaction and is also suitable in this respect.

In particular, the acidic treatment liquid containing metal ions described above preferably further contains nickel ions. Nickel ions include nickel ions (Ni ²⁺ ) and nickel complex ions. By making nickel ions coexist with the metal ions described above, it is possible to promote the substitution reaction of the film with the metal ions coexisting with the nickel ions. In this case, the concentration of the nickel ions in the acidic treatment liquid is preferably 0.001 to 1 mol / L.

  In the present invention, the treatment temperature and treatment time of the acidic treatment liquid are the composition of the acidic treatment liquid and the formed nickel-phosphorus alloy film (composition of the electroless nickel-phosphorous plating bath used for forming the nickel-phosphorus alloy film). Although it determines suitably by etc. and it does not restrict | limit in particular, 0-60 degreeC, Preferably the processing temperature of 20-60 degreeC and the processing time for 0.1-10 minutes can be applied suitably.

  Moreover, the film obtained by the treatment with the acidic treatment liquid can be further heat-treated after being treated with the acidic treatment liquid. Even if the film is only treated with an acidic treatment solution, it has excellent physical properties compared to the conventional one, but the obtained film can improve the film hardness without fading black by heat treatment. Therefore, it is possible to obtain a film exhibiting a good black color while having a higher hardness by heat treatment. In this case, as heat treatment conditions, for example, it is effective to heat-treat at 100 to 400 ° C. for 0.1 to 100 minutes in the air (in an air atmosphere).

  According to the present invention, it is possible to obtain a good black nickel film having no interference color even when the thickness of the formed black nickel film is thin, and the present invention is 100 μm or less, particularly 0.1 to 10 μm. It is suitable for forming a black nickel film of a degree.

EXAMPLES Hereinafter, although an Example , a reference example, and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to the following Example.

[Reference Examples 1 and 2 , Examples 1 to 3 , Comparative Example 1]
An Al plate (JIS1050) was used as an object to be plated, and the following treatments were sequentially performed as pretreatment on the Al plate.
Immerse in UA-68 (manufactured by Uemura Kogyo Co., Ltd.) for 5 minutes at 50 ° C. Immerse in AZ-102 (manufactured by Uemura Kogyo Co., Ltd.) for 1 minute at 60 ° C. (1: 1) Immerse in AZ-301 (manufactured by Uemura Kogyo Co., Ltd.) for 30 seconds at 25 ° C. (1: 1) Immerse in nitric acid for 20 sec. At 20 ° C.

  Next, in an electroless nickel-phosphorous plating bath containing nickel nitrate 0.1 mol / L, sodium hypophosphite 0.1 mol / L and citric acid 0.2 mol / L and having a pH of 4.5, The pretreated Al plate was immersed at 90 ° C. for 10 minutes to form an underlayer.

  Next, adjust the time so that the thickness of the nickel-phosphorus alloy film to be formed on the Al plate on which the base layer is formed in the electroless nickel-phosphorous plating bath shown in Table 1 is 80 ° C. And dipped to form an electroless nickel-phosphorus alloy plating film.

Subsequently, this operation was repeated for each plating bath, and 100 g / L (Fe ^{3+) of} ferric chloride was applied to the Al plate on which the electroless nickel-phosphorous plating film corresponding to the first turn, the third turn, and the fifth turn was formed. About 0.37 mol / L) and an acidic treatment liquid containing 200 g / L of hydrochloric acid, and a black nickel treatment was performed by immersion in the acidic treatment liquid at 25 ° C. for 1 minute to obtain a black nickel film. The brightness of the resulting black nickel coating and the presence or absence of interference colors were evaluated by the following methods. The results are shown in Table 2.

Lightness (L value)
It measured with the light source (C / 10) using the spectroscopic color difference meter (Nippon Denshoku: SQ-2000).
The film with or without an interference color was observed by irradiating a fluorescent lamp with light from a fluorescent lamp.

[Examples 4 to 6 ]
A black nickel film was formed in the same manner as in Example 3 except that the acidic treatment solution was blackened in place of A (Example 4 ), B (Example 5 ), and C (Example 6 ) in Table 3 below. The black nickel film thus obtained was evaluated in the same manner as in Reference Example 1. The results are shown in Table 4.

[Example 7 , Comparative Example 2]
After pre-treating the Al plate by the same method as in each of Example 3 and Comparative Example 1 and applying the blackening treatment to the first turn film on which the base layer and the electroless nickel-phosphorus alloy plating film were formed, Further, a heat treatment was performed at 300 ° C. for 60 minutes to obtain a black nickel film. About the obtained black nickel membrane | film | coat, the brightness | luminance and the presence or absence of the interference color were evaluated by the method similar to the reference example 1, and film | membrane hardness was evaluated by the following method. The results are shown in Table 5.

The Vickers hardness was measured using a film hardness microhardness tester (Akashi: HM-124).

[Examples 8 to 17 ]
Except that the compounds shown in Table 6 instead of benzothiazole was used in the amounts shown in Table 6 to form a black nickel coating in the same manner as in Example 3, the resulting black nickel coating, as in Reference Example 1 Evaluation was made in the same manner. The results are shown in Table 7.

Claims (9)

One or more kinds selected from nickel salt, phosphate, organic acid and / or salt thereof, thioether compound, thiocyanate compound, thiocarbonyl compound, thiol compound, thiosulfuric acid and thiosulfate on the object to be plated A nickel-phosphorus alloy film is formed by electroless plating using an electroless nickel-phosphorous plating bath containing a sulfur-based compound and ammonium ions and not containing an amino group-containing compound. A method for forming a black nickel film, comprising: treating an alloy film by contacting with an acidic treatment solution. 2. The method for forming a black nickel film according to claim 1, wherein the pH of the electroless nickel-phosphorous plating bath is 5-8 .   The method for forming a black nickel film according to claim 1 or 2, wherein the acidic treatment liquid contains one or more ions of a metal selected from iron, copper, silver, cobalt, manganese and molybdenum. .   4. The method for forming a black nickel film according to claim 3, wherein the acidic treatment liquid further contains nickel ions.   5. The black according to claim 1, wherein the nickel-phosphorus alloy film is treated by contacting with an acidic treatment solution, and then the treated nickel-phosphorus alloy film is further heat-treated. Method for forming a nickel film. An electroless nickel-phosphorous plating bath for forming the nickel-phosphorous alloy film used to form a black nickel film by blackening by a treatment in which the nickel-phosphorus alloy film is brought into contact with an acidic treatment liquid, comprising a nickel salt , Phosphate, organic acid and / or salt thereof, thioether compound, thiocyan compound, thiocarbonyl compound, thiol compound, thiosulfuric acid and thiosulfate, one or more sulfur compounds, and ammonium ion An electroless nickel-phosphorus plating bath characterized by containing an amino group-containing compound. The electroless nickel-phosphorus plating bath according to claim 6, wherein the pH is 5-8 .   The electroless nickel-phosphorous plating according to claim 6 or 7, wherein the acidic treatment liquid contains one or more ions of a metal selected from iron, copper, silver, cobalt, manganese and molybdenum. bath.   9. The electroless nickel-phosphorous plating bath according to claim 8, wherein the acidic treatment liquid further contains nickel ions.