JP3139239B2 - Electroless composite plating bath - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroless composite plating bath in which water-insoluble fine particles such as fluororesin or short fibers are co-deposited in a plating film simultaneously with the deposition of the plating film by electroless (chemical) plating. About.

[0002]

2. Description of the Related Art Fine particles and short fibers of fluorine resin, graphite, graphite fluoride, molybdenum disulfide, boron nitride, etc. have been conventionally used in an electroless plating solution such as an electroless nickel plating solution. A metal plating is chemically deposited by immersing the object to be plated in the composite plating bath, and fine particles and short fibers are co-deposited in the metal coating, and the metal matrix is dispersed in the metal matrix. It is known to form a composite plating film in which the fine particles and short fibers are dispersed.

For example, polytetrafluoroethylene (P
By immersing the object to be plated in a composite plating bath in which fine particles of TFE) are dispersed in an electroless Ni-P plating solution,
It is known that a composite plating film in which PTFE particles are eutectoidally dispersed in an i-P alloy matrix is formed on an object to be plated, thereby imparting the lubricity and wear resistance of the PTFE particles to the Ni-P alloy. A film is obtained and this electroless Ni
The P / PTFE composite plating film is used for various applications such as applications requiring lubricity and wear resistance of sliding members and the like.

In this case, water-repellent particles such as fluororesin, graphite, and fluorinated graphite are inferior in wettability to the plating solution and cannot be dispersed in the plating solution as it is.
Usually, a water-soluble cationic surfactant is used as a dispersing aid to improve the dispersibility of the water-repellent particles, and composite plating is performed.

[0005] However, the plating bath using a cationic surfactant which has been conventionally used has problems such as poor film appearance and uneven deposition at an acute angle portion of an object to be plated. Therefore, in the case of actual plating, very strict restrictions on the composition of the plating bath, plating conditions, and plating methods and difficult know-how based on experience are required. It was difficult to apply the method to barrel plating or a large plating object of 1 m square or more.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to easily obtain a film having a good appearance without causing uneven deposition, thereby enabling barrel plating and composite plating of a large plating object. An object of the present invention is to provide an electroless composite plating bath.

[0007]

The present inventors have made intensive studies to achieve the above object, and as a result, dispersed water-insoluble fine particles or short fibers with a cationic surfactant to form a metal plating film (matrix). A) a compound represented by the following formula (1) as a cationic surfactant in an electroless composite plating bath for plating an electroless composite plating film in which these water-insoluble fine particles or short fibers are dispersed and composited in Even when applied to electroless barrel plating or electroless plating of large-sized workpieces, a fine-grained composite plating film with uniform eutectoid dispersion of fine particles such as fluororesin and short fibers is uniformly deposited. It has been found that they can be easily and surely formed without causing the occurrence of a crack.

[0008]

Embedded image (Where A _{1 to} A ₉ are a hydrogen atom or a lower alkyl group,
R _{1 to} R ₈ are a hydrogen atom, a hydroxyl group or a lower alkyl group, X is an anion having an atomic weight or a molecular weight of 100 or less, and n is a valence of X. )

In this case, it is known that the cationic surfactant represented by the above formula (1) is used for a composite electroplating bath (Japanese Patent Publication No. 4-28797).

However, since the electroless composite plating bath contains a reducing agent, a dispersant (surfactant) for dispersing the composite material (water-insoluble fine particles and short fibers) in the plating bath is used as a reducing agent. When the dispersant used for electroplating is used for electroless plating, it is possible to uniformly disperse the composite material in the plating bath, but the appearance of the resulting composite plating film In some cases (for example, spots or streaks may occur), impair plating deposition, and cause unevenness.

In fact, in the above formula (1), in the case of performing electroless composite plating using a compound that is conventionally used and is commercially available, wherein X is iodine, if the electro-composite plating is performed, Although a good composite plating film was obtained and the dispersibility of the composite material in the electroless composite plating bath and the wettability of the composite material were good, the hypophosphite and dimethylamine borane used for the electroless composite plating were good. X in the formula (1) has a large atomic weight, such as iodine, against the reduction reaction of metal ions that occurs simultaneously with the oxidation of a reducing agent such as (DMAB). It has been found that critical defects are likely to occur.

However, when the compound of the formula (1) is an anion having an atomic weight or a molecular weight of 100 or less, for example, fluorine, chlorine, bromine, etc., the dispersibility of the composite material in the plating bath and the wettability of the composite material Good electroless composite plating film with good appearance and no unevenness, without adversely affecting the appearance of the electroless composite plating film or hindering the deposition of the electroless plating. It has been found that the present invention can be obtained, and the present invention has been accomplished.

Accordingly, the present invention provides an electroless composite plating bath in which water-insoluble fine particles or short fibers are dispersed with a cationic surfactant, wherein the compound represented by the above formula (1) is used as the cationic surfactant. An electroless composite plating bath characterized by being used.

Hereinafter, the present invention will be described in more detail. The electroless composite plating bath of the present invention uses a cationic surfactant represented by the following formula (1) as described above.

[0015]

Embedded image

In the formula (1), A _{1 to} A ₉ represent a hydrogen atom or a lower alkyl group such as a methyl group or an ethyl group, and R _{1 to} R ₈ represent a hydrogen atom, a hydroxyl group or a lower group such as a methyl group or an ethyl group. The alkyl group, X, is an anion having an atomic weight or molecular weight of 100 or less, for example, a fluorine atom, a chlorine atom, a bromine atom or a sulfate group. n is the valence of X, and is 1 for a halogen atom of fluorine, chlorine or bromine, and 2 for a sulfate group. In this case, the use amount of the cationic surfactant of the above formula (1) is preferably 500 ppm or less, particularly preferably in the range of 100 to 300 ppm.

In the electroless composite plating bath of the present invention, a composite material (water-insoluble fine particles or short fibers) is added to an electroless plating solution such as an electroless nickel plating solution, a cobalt plating solution, or an alloy plating solution of the above formula (1). The composition of the electroless plating solution can be a known composition, although the composition is dispersed by the cationic surfactant of the above (1). In this case, a boron-based reducing agent such as hypophosphite or dimethylamine borane is used as a reducing agent in the electroless nickel plating solution, the cobalt plating solution, and the alloy plating solution thereof.

The composite material is appropriately selected, for example, a fluororesin such as polytetrafluoroethylene, graphite, fluorinated graphite, molybdenum disulfide, boron nitride and the like. The particle size of the composite material is 0.01 to 30 μm. , Especially 0.1-10μ
The range of m is preferred. The amount of the composite used is usually 0.5 to 50 g / l, particularly 1 to 10 g / l.

Further, the electroless composite plating bath to which the surfactant of the above formula (1) is added exhibits its effect particularly in a plating bath having a pH of 4 to 10.

The conditions for electroless plating using the electroless composite plating bath of the present invention can be ordinary plating conditions.

[0021]

The electroless composite plating bath of the present invention provides an electroless composite plating film having a good appearance and no unevenness even when applied to electroless barrel plating or to a large-sized workpiece. Is to give.

[0022]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Examples 1 and 2, Comparative Examples 1 and 2] A 1 × 1 m steel plate was prepared on a 1 × 1 m steel plate under the following conditions using an electroless composite plating bath having the following composition using a cationic surfactant shown in Table 1. Electrolytic composite plating was performed to obtain an electroless composite plating film of about 10 μm. Table 1 shows the results of visual observation of the appearance of the plating film and the presence or absence of unevenness. Plating solution composition and conditions PTFE fine particles (average particle size 0.2 μm) 3 g / l cationic surfactant 40 ppm nickel sulfate 20 g / l nickel citrate 8 g / l sodium malonate 15 g / l sodium hypophosphite 20 g / l ammonium sulfate 10g / l pH 5.0 Bath temperature 90 ° C Stirring Mild mechanical stirring

[0024]

[Table 1]

[Examples 3 and 4, Comparative Examples 3 and 4] The same plating bath and plating conditions as those in Examples 1 and 2 were used, and the length was 50 m.
A steel bolt having a size of m and φ5 mm was barrel-plated. In this case, the rotation speed of the barrel is 20 rpm,
Plating was performed for 60 minutes.

Table 2 shows the results of evaluating the appearance of the plating film and the presence or absence of unevenness.

[0027]

[Table 2]

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C23C 18/00-18/54

Claims (1)

(57) [Claims] 1. An electroless composite plating bath in which water-insoluble fine particles or short fibers are dispersed with a cationic surfactant, wherein the cationic surfactant is represented by the following formula (1):
An electroless composite plating bath characterized by using a compound represented by the formula: Embedded image (Where A _{1 to} A ₉ are a hydrogen atom or a lower alkyl group,
R _{1 to} R ₈ are a hydrogen atom, a hydroxyl group or a lower alkyl group, X is an anion having an atomic weight or a molecular weight of 100 or less, and n is a valence of X. )