JP4780585B2 - Electroless nickel plating solution - Google Patents

Description

  The present invention relates to an electroless nickel plating solution and an electroless nickel plating method.

  Electroless nickel plating has excellent film properties and good uniform precipitation, and is widely used in various fields such as electronic parts and automobile parts.

  As one of the problems of electroless nickel plating, when performing long-term continuous use, plating deposition on parts other than the object to be plated due to poor liquid management or incorporation of impurities, sudden abnormal precipitation phenomenon, so-called For example, decomposition of the plating solution occurs.

For this reason, a stabilizer is usually added to the electroless nickel plating solution so that the decomposition of the plating solution is suppressed and it can be used stably for a long period of time. For example, Patent Document 1 described below describes that Pb ²⁺ , Cd ²⁺ , CN ^{− and the} like are effective as stabilizers for electroless nickel plating, and these stabilizers have been widely put into practical use. Furthermore, Non-Patent Document 1 described below describes that heavy metals are effective as a stabilizer for an electroless nickel plating solution.

However, Pb ²⁺ , Cd ²⁺ , CN ⁻ , heavy metals, and the like described in these documents are known to have adverse effects on the human body and the environment, and in recent years there has been a movement to eliminate such harmful substances. Is active.

For this reason, there is a demand for a stabilizer that can be used as an alternative to these. However, there has been no discovery of a stabilizer made of a highly safe substance that does not adversely affect the deposition properties of the plating solution and the film properties. Is the current situation.
U.S. Pat.No. 2,762,723 J. Elze, J. Metall 14, 1960 2, 104

  The present invention has been made in view of the current state of the prior art described above, and its main purpose is to provide good stability without impairing the precipitation of the electroless nickel plating solution. An object of the present invention is to provide a stabilizer for electroless nickel plating made of a highly safe substance.

  As a result of intensive studies to achieve the above-mentioned object, the present inventor has obtained at least one selected from the group consisting of allylamine, allylamine salt, diallylamine, diallylamine salt, diallylammonium salt, lysine, lysine salt, and dicyandiamide. It has been found that a polymer having a compound as a constituent monomer has excellent performance as a stabilizer for an electroless nickel plating solution, and the present invention has been completed here.

That is, the present invention provides the following stabilizer for electroless nickel plating solution, electroless nickel plating solution, and electroless nickel plating method.
1. A stabilizer for an electroless nickel plating solution comprising a polymer comprising at least one compound selected from the group consisting of allylamine, allylamine salt, diallylamine, diallylamine salt, diallylammonium salt, lysine, lysine salt, and dicyandiamide.
2. Homopolymer containing 50 mol% or more of at least one compound selected from the group consisting of allylamine, allylamine salt, diallylamine, diallylamine salt, diallylammonium salt, lysine, lysine salt, and dicyandiamide as a constituent monomer. Item 2. The stabilizer for electroless nickel plating solution according to Item 1, which is a copolymer.
3. Item 3. The stabilizer for electroless nickel plating solution according to Item 1 or 2, wherein the polymer has a weight average molecular weight of 500 to 200,000.
4). An electroless nickel plating solution comprising the stabilizer according to any one of Items 1 to 3.
5. Item 5. The electroless nickel plating solution according to item 4, wherein the electroless nickel plating solution is an aqueous solution containing a water-soluble nickel salt, a complexing agent, and a reducing agent in addition to the stabilizer.
6). 6. An electroless nickel plating method comprising contacting an object to be plated with the electroless nickel plating solution according to item 4 or 5.

  The stabilizer blended in the electroless nickel plating solution of the present invention is composed of at least one compound selected from the group consisting of allylamine, allylamine salt, diallylamine, diallylamine salt, diallylammonium salt, lysine, lysine salt, and dicyandiamide. As a polymer.

  Examples of the allylamine salt, diallylamine salt, and lysine salt include water-soluble salts such as hydrochloride, sulfate, and acetate.

  A polymer containing at least one compound selected from the group consisting of allylamine, allylamine salt, diallylamine, diallylamine salt, diallylammonium salt, lysine, lysine salt, and dicyandiamide as a constituent monomer is composed of only one kind of constituent monomer. It may be a homopolymer or a copolymer containing two or more kinds of constituent monomers.

  In addition to the above constituent monomers, a copolymer containing sulfur dioxide, acrylamides, maleic acid, alkylene amines, formaldehyde and the like as constituent monomers may be used. In this case, the amount of at least one compound selected from the group consisting of allylamine, allylamine salt, diallylamine, diallylamine salt, diallylammonium salt, lysine, lysine salt, and dicyandiamide is about 50 mol% in the total constituent monomers. The above is preferable.

  The polymer preferably has a weight average molecular weight of about 500 to 200,000.

  Specific examples of the polymer include allylamine polymer, allylamine hydrochloride polymer, allylamine amide sulfate polymer, allylamine hydrochloride / dimethylallylamine hydrochloride copolymer, allylamine / dimethylallylamine copolymer, allylamine hydrochloride / Diallylamine hydrochloride copolymer, allylamine acetate / diallylamine acetate copolymer, diallylamine polymer, diallylamine hydrochloride polymer, methyldiallylamine hydrochloride polymer, methyldiallylamine amide sulfate polymer, methyldiallylamine acetate polymer, Diallyldimethylammonium chloride polymer, diallylamine hydrochloride / sulfur dioxide copolymer, diallylmethylethylammonium ethyl sulfate / sulfur dioxide copolymer, diallylamine acetate / sulfur dioxide copolymer, Rudiallylamine hydrochloride / sulfur dioxide copolymer, diallyldimethylammonium chloride / sulfur dioxide copolymer, diallyldimethylammonium chloride / acrylamide copolymer, (partially 3-chloro-2-hydroxypropylated) diallyldimethylammonium chloride / diallylamine Hydrochloride copolymer, diallylamine hydrochloride / maleic acid copolymer, diallylamine amide sulfate / maleic acid copolymer, diallyldimethylammonium chloride / maleic acid / sulfur dioxide copolymer, lysine polymer, lysine hydrochloride polymer Dicyandiamide / polyalkylpolyamine polycondensate, dicyandiamide / formalin polycondensate, and the like.

  Among these, particularly preferred polymers are allylamine polymer, allylamine hydrochloride polymer, allylamine amide sulfate polymer, allylamine hydrochloride / dimethylallylamine hydrochloride copolymer, allylamine / dimethylallylamine copolymer, allylamine hydrochloride. And salt / diallylamine hydrochloride copolymer, allylamine acetate / diallylamine acetate copolymer, lysine polymer, lysine hydrochloride polymer, dicyandiamide / polyalkylpolyamine polycondensate, dicyandiamide / formalin polycondensate and the like.

  In this invention, the said polymer can be used individually by 1 type or in mixture of 2 or more types.

  The electroless nickel plating solution of the present invention may have the same composition as a known electroless nickel plating solution except that the polymer is contained as a stabilizer.

  Specifically, the above polymer may be added to an electroless nickel plating solution comprising an aqueous solution containing a water-soluble nickel compound, a complexing agent and a reducing agent as a basic bath.

  The concentration of the polymer in the plating solution is preferably about 0.01 mg / l to 100 g / l, and more preferably about 0.1 mg / l to 1 g / l. If the concentration of the polymer is too low, sufficient stability cannot be imparted and the plating solution is likely to be decomposed, which is not preferable. On the other hand, if the concentration is too high, the deposition rate of the plating film is lowered, and the precipitation reaction may not occur.

  The water-soluble nickel compound is not particularly limited, but examples thereof include water-soluble nickel inorganic salts such as nickel sulfate, nickel chloride and nickel hypophosphite, and water-soluble nickel organic salts such as nickel acetate and nickel malate. Can be used. These nickel compounds can be used singly or in combination of two or more.

  The concentration of the water-soluble nickel compound is preferably about 0.001 to 1 mol / l, and more preferably about 0.01 to 0.3 mol / l. When the concentration of the water-soluble nickel compound is too low, the deposition rate of the film becomes very slow, and it takes a long time for film formation, which is not preferable. On the other hand, when the concentration of the water-soluble nickel compound is too high, the viscosity of the plating solution is increased, the fluidity of the solution is lowered, adversely affecting the uniform precipitation, and further increasing the cost, which is not preferable.

  The complexing agent is an effective component for preventing the precipitation of the nickel compound and further allowing the nickel precipitation reaction to have an appropriate rate, and various complexing agents used in known electroless nickel plating solutions. Can be used. Specific examples of such a complexing agent include dicarboxylic acids such as oxalic acid and adipic acid and soluble salts thereof; oxycarboxylic acids such as malic acid and tartaric acid; soluble salts thereof; aminocarboxylic acids such as glycine and alanine; Soluble salts; ethylenediamine tetraacetic acid, ethylenediamine derivatives such as versenol (N-hydroxyethylethylenediamine-N, N ′, N′-triacetic acid), quadrol (N, N, N ′, N′-tetrahydroxyethylethylenediamine), Examples thereof include phosphonic acids such as 1-hydroxyethane-1,1-diphosphonic acid and ethylenediaminetetramethylenephosphonic acid, and soluble salts thereof. These complexing agents can be used singly or in combination of two or more.

  The concentration of the complexing agent varies depending on the type and is not particularly limited, but is usually preferably about 0.001 to 2 mol / l, more preferably about 0.002 to 1 mol / l. preferable. If the concentration of the complexing agent is too low, nickel hydroxide is likely to be precipitated, and further, since the oxidation-reduction reaction is too fast, the plating solution is likely to be decomposed. On the other hand, if the concentration of the complexing agent is too high, the deposition rate of the plating film becomes very slow, and further, the viscosity of the plating solution becomes high.

  As the reducing agent, various reducing agents used in known electroless nickel plating solutions can be used. Specific examples thereof include hypophosphite compounds such as sodium hypophosphite and potassium hypophosphite; borohydride compounds such as sodium borohydride, potassium borohydride and dimethylamine borane; hydrazines and the like. It is done.

  The concentration of the reducing agent varies depending on the type and is not particularly limited, but is usually preferably about 0.001 to 1 mol / l, and preferably about 0.002 to 0.5 mol / l. More preferred. If the concentration of the reducing agent is too low, the reduction of nickel ions in the plating solution is slow and it takes time to form a film. On the other hand, when the concentration of the reducing agent is too high, decomposition of the plating solution tends to occur, which is not preferable.

  The electroless nickel plating solution of the present invention may further contain various known additives blended in the electroless nickel plating solution as necessary.

  The electroless nickel plating solution of the present invention is preferably about pH 3-12, more preferably about pH 4-10. If the pH is too low, the smooth progress of the reduction reaction is hindered, and the reducing agent is decomposed and the deposition of the plating is lowered, which is not preferable. On the other hand, if the pH is too high, the stability of the plating solution tends to decrease, and the plating solution may be decomposed, which is not preferable.

  There is no particular limitation on the method of forming the electroless nickel film using the electroless nickel plating solution of the present invention, and the object to be plated is changed to an electroless nickel plating solution until a nickel plating film having a required thickness is formed. What is necessary is just to contact. Usually, it may be processed by a method of immersing an object to be plated in an electroless nickel plating solution.

  About the liquid temperature at the time of performing electroless nickel plating, although it changes with the composition of a specific plating solution, etc., it is preferable to usually be about 25 degreeC or more, and it is more preferable to set it as about 40-100 degreeC. When the temperature of the plating solution is too low, the plating deposition reaction becomes slow, and the nickel plating film is not easily deposited and the appearance is liable to occur. On the other hand, if the temperature of the plating solution is too high, the evaporation of the plating solution becomes intense, making it difficult to maintain the plating solution composition within a predetermined range, and further, the plating solution is likely to be decomposed, which is not preferable. Moreover, you may stir the electroless nickel plating liquid as needed.

  There is no limitation in particular about the kind of to-be-plated object, The thing similar to the target object of normal electroless nickel plating can be used as a to-be-plated object. Moreover, about the to-be-plated object which does not have catalyst activity, such as plastics, after providing catalysts, such as palladium, according to a conventional method, electroless nickel plating may be performed.

  The stabilizer for electroless nickel plating solution of the present invention has a safer substance as an active ingredient compared with the stabilizer for conventional electroless nickel plating, and is extremely effective in that it has less adverse effects on the human body and the environment. It is highly useful.

  The electroless nickel plating solution of the present invention containing such a stabilizer can be used stably for a long period of time without causing decomposition or abnormal precipitation of the plating solution, and there is no significant decrease in the deposition rate. The appearance of the nickel plating film is also good.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
Using an electroless nickel plating solution having the following composition as a basic bath, an additive shown in Table 1 below was added to prepare an electroless nickel solution.
Basic bath composition Nickel sulfate 25g / l
Sodium hypophosphite 25g / l
Malic acid 20g / l
Acetic acid 5g / l

  Using each electroless nickel plating solution containing the additives shown in Table 1, each sample of 96% alumina ceramic, mild steel plate (JIS-SPCC SB), and rolled copper plate (JIS-1020 p) (5 × 5 cm) Was plated for 1 hour in an electroless nickel plating solution having a pH of 4.7 and a bath temperature of 90 ° C. to form an electroless nickel plating film.

The pretreatment process and chemicals used are as follows.
1. 96% alumina ceramic (1) Degreasing (trade name: OPC-370 Condy Clean M, manufactured by Okuno Pharmaceutical Co., Ltd.)
(2) Catalyst addition (trade name: OPC-80 catalyst, manufactured by Okuno Pharmaceutical Co., Ltd.)
(3) Activation (trade name: OPC-505 accelerator, manufactured by Okuno Pharmaceutical Co., Ltd.)
2. Mild steel plate (1) Immersion degreasing (trade name: A-screen 801, manufactured by Okuno Pharmaceutical Co., Ltd.)
(2) Electrolytic degreasing (trade name: Top Cleaner E, manufactured by Okuno Pharmaceutical Co., Ltd.)
(3) Acid activity (trade name: Top acid, manufactured by Okuno Pharmaceutical Co., Ltd.)
3. Rolled copper plate (1) Immersion degreasing (Trade name: A-screen 801, manufactured by Okuno Pharmaceutical Co., Ltd.)
(2) Electrolytic degreasing (trade name: Top Cleaner E, manufactured by Okuno Pharmaceutical Co., Ltd.)
(3) Activation (trade name: ICP Axela, manufactured by Okuno Pharmaceutical Co., Ltd.).

About each electroless nickel plating film formed by the above-mentioned method, the characteristic was evaluated by the following method. The results are shown in Table 2 below.
1. Plating deposition rate and phosphorus content / boron content Measured using a fluorescent X-ray film thickness meter.
2. Film appearance The plated specimen was visually observed and evaluated according to the following criteria.
Good: There is no abnormality in the appearance of the plating film, and a uniform plating film is formed on the entire surface.
Zara: A state in which a large number of protrusions are confirmed on the surface of the plating film.
Non-uniformity: The state where the plating film is not deposited or the film thickness is extremely thin for a specific part.
3. Bath stability After completion of the plating treatment, the plating solution was held at the same temperature as the plating treatment temperature for 3 hours, and then the state of the plating solution was observed.

  As is clear from the above results, for the present plating solutions 1 to 9 containing the above polymer, an electroless nickel plating film having a good appearance can be formed without significantly reducing the deposition rate. The stability was also very good.

  On the other hand, the comparative plating solution 1 containing no stabilizer has a rough surface on the surface of the electroless nickel plating film to be formed, and the plating solution is decomposed after the completion of plating, resulting in poor bath stability. there were. Further, in the comparative plating solution 2 containing lead nitrate as a stabilizer, the formed electroless nickel plating film is in a non-uniform deposition state depending on the type of material, and abnormal deposition occurs when left after the end of plating. Produced and inferior in stability.

Example 2
Using an electroless nickel plating solution having the following composition as a basic bath, an electroless nickel solution to which the additives shown in Table 3 below were added was prepared.

Basic bath composition Nickel sulfate 26.3 g / l
Dimethylamine borane 1.5g / l
Trisodium citrate 25.8 g / l

96% alumina ceramic, mild steel sheet (JIS-SPCC SB), and rolled copper sheet (JIS-1020 p) samples (5 x 5 cm) using each electroless nickel plating solution containing the additives shown in Table 3 Was immersed in an electroless nickel plating solution having a pH of 8.0 and a bath temperature of 70 ° C. for 1 hour to form an electroless nickel plating film.
The pretreatment method and the evaluation method are the same as in Example 1. The results are shown in Table 4 below.

  As is clear from the above results, the present plating solutions 10 to 18 containing the above polymer can form an electroless nickel plating film having a good appearance without greatly reducing the deposition rate, and the bath stability is also good. It was good.

  On the other hand, the comparative plating solution 3 containing no stabilizer was inferior in bath stability because the plating solution was decomposed during electroless plating. Further, in the comparative plating solution 4 containing lead nitrate as a stabilizer, the surface of the formed electroless nickel plating film is rough, and the plating solution is decomposed after the completion of plating, resulting in poor bath stability. .

Claims (6)

A stabilizer for an electroless nickel plating solution comprising a polymer comprising at least one compound selected from the group consisting of allylamine, allylamine salt, diallylamine, diallylamine salt, diallylammonium salt, lysine, lysine salt, and dicyandiamide. Homopolymer containing 50 mol% or more of at least one compound selected from the group consisting of allylamine, allylamine salt, diallylamine, diallylamine salt, diallylammonium salt, lysine, lysine salt, and dicyandiamide as a constituent monomer. The stabilizer for electroless nickel plating solution according to claim 1 which is a copolymer.   The stabilizer for electroless nickel plating solution according to claim 1 or 2, wherein the polymer has a weight average molecular weight of 500 to 200,000.   An electroless nickel plating solution comprising the stabilizer according to claim 1.   The electroless nickel plating solution according to claim 4, wherein the electroless nickel plating solution is an aqueous solution containing a water-soluble nickel salt, a complexing agent, and a reducing agent in addition to the stabilizer.   An electroless nickel plating method, wherein an object to be plated is brought into contact with the electroless nickel plating solution according to claim 4 or 5.