JPH0613753B2 - Method for producing solution containing fine metal body used for electroless plating - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a solution containing a fine metal body used for electroless plating, using nickel, cobalt, copper ions, or the like. is there.

[Conventional technology]

Conventionally, as a method for performing electroless plating that has been widely used for a non-conductive substance and an electroless plating deposition reaction that does not easily occur, the stannous chloride hydrochloric acid solution is used as the plating object. Immersion, stannous ion binding with strong reducing power, washing with water, then immersion in hydrochloric acid solution of palladium chloride, redox reaction to deposit palladium nuclei on the surface of the object to be plated, using palladium nuclei as a catalyst for electroless plating It is well known to carry out the above to obtain a plating film. There are also some known methods using palladium or tin colloid.

(Japanese Patent Laid-Open Publication Nos. 61-207667 and 61-18
However, since these methods use a noble metal as a nucleus, there is a drawback that the noble metal catalyst separated from the object to be plated in the electroless plating solution becomes a major factor of self-decomposition of the electroless plating solution. In addition, since the catalyst is a noble metal, there is a drawback that the cost of the working process of applying the catalyst is large in the production cost. Further, the method using the stannous chloride solution has a drawback that the surface of the object to be plated, which is weak against acidity or hydrochloric acid, is damaged.

[Problems to be solved by the invention]

Since the conventional electroless plating catalyst utilizes a noble metal catalyst, the electroless plating solution is self-decomposed by the mixture of the noble metal catalyst, the production cost is increased by using the noble metal catalyst, and the surface of the object to be plated contains the noble metal catalyst. Although it has a drawback of being damaged by an acidic aqueous solution, the present invention overcomes those problems and is advantageous in that it can be used as a substitute for a noble metal catalyst in a simple operation and can be mass-produced at low cost, and industrially implemented. An object of the present invention is to provide a solution containing a fine metal body, which is a substitute for a catalyst used for various electroless plating.

[Means for solving problems]

In order to achieve the above object, the present invention has conducted intensive studies on electroless plating, and as a result, solved the above problems for the first time without using a precious metal catalyst.

That is, it has been discovered that reduction of nickel, cobalt, and copper ions can be used as a catalyst substitute for electroless plating, and the present invention has been completed based on this finding. In the present invention, an aqueous solution containing nickel, cobalt, and copper ions is subjected to a reduction treatment with a reducing agent to form a fine metal body, which is then used as a substitute for the electroless plating catalyst.

In order to obtain an aqueous metal salt solution in the present invention, a metal salt compound that is soluble in water using water as a catalyst is used.

Representative examples are nickel (II) acetate tetrahydrate, nickel (II) sulfate ammonium hexahydrate, nickel (II) carbonate tetrahydrate, nickel (II) chloride hexahydrate. ,
Nickel (II) sulfate hexahydrate, cobalt (II) acetate
Tetrahydrate, Cobalt (II) Ammonium Hexahydrate, Cobalt (II) Chloride Hexahydrate, Diammonium Cobalt (II) Hexahydrate, Cobalt Phosphate Octahydrate, Sulfuric Acid Cobalt (II) heptahydrate, copper (II) acetate monohydrate, copper (II) hydrochloride dihydrate, diammonium copper (II) chloride dihydrate, copper phosphate (II ) ・ Trihydrate, potassium chloride (II) chloride ・ dihydrate, copper (II) sulfate ・ pentahydrate,
And nickel (II) chloride, nickel (II) sulfate, copper (II) chloride, copper (II) sulfate, cobalt (II) chloride, cobalt (II) sulfate and the like.

The chemical used as the reducing agent is subjected to reduction treatment by using sodium borohydride, potassium borohydride, dimethylamine borane, or the like. In order to disperse the fine metal body in the solution, it is necessary to mix the dispersant in an aqueous solution containing metal ions in advance and to stir it before carrying out the reduction treatment.

Gelatin is used as a dispersant, and a surfactant is added depending on the object to be plated. The purpose of using gelatin is to use the metal body in the solution in a uniformly dispersed state. In the case of a surfactant, in addition to the purpose of achieving a uniform dispersed state similar to gelatin, it also lowers the surface tension of the surface of the object to be plated and increases the amount of metal bodies attached to the surface of the object to be plated in the solution. have. The aqueous solution is adjusted with a dispersant so that the fine metal body is dispersed in a solution and easily adheres to the object to be plated.

The stabilizer added to the solution is added for the purpose of stabilizing the solution of the fine metal body.

It is added for the purpose of preventing the fine metal body from returning to ions by providing the atmosphere of the solution of the fine metal body in the liquid in a state where a gradual reduction reaction occurs. Dimethylamine borane or sodium hypophosphite is used as a stabilizer, and is added in a range of 3 to 40 g / to stabilize a solution of fine metal bodies.

Depending on the surface condition of the object to be plated, the solution containing fine metal bodies can be changed to a pH within the range of 1 to 10. For example, when the solution is immersed in an alkaline solution depending on the type of plastic. The plastic surface is over-etched, and if it is used as it is, it will have an unsuitable surface condition for plating. In this case, it is necessary to change the pH. When changing the pH, after adding a complexing agent, add an acidic aqueous solution such as sulfuric acid or hydrochloric acid or an alkaline substance such as sodium hydroxide so that the surface condition of the plated object is not damaged. Change to the value of and use. When adjusting the pH, add a complexing agent to prevent hydroxide formation.

Complexing agents use monocarboxylic acids, dicarboxylic acids, oxycarboxylic acids, and carboxylates. Benzoic acid, succinic acid, lactic acid, sodium acetate, etc. are typical examples.
The amount is adjusted to 10 to 50 g / percent so as to prevent the formation of hydroxide by the complexing agent, and then the pH is adjusted before use.

Ion-exchanged water or distilled water is used as the solvent.

Thus, the above-mentioned reagents are used to produce a solution containing a fine metal body which is a catalyst substitute for electroless plating.

The metal salt is dissolved in the solvent in the range of 5 to 50 g /, the dispersant is dissolved in the concentration range of 1 to 10 g /, and the metal ion is reduced while stirring.

The concentration of the reducing agent varies somewhat depending on the metal ion concentration and the type of metal salt, but it is usually used within the range of 1 to 40 g /.

For the object to be plated produced by the above procedure, which does not easily cause the deposition of the non-conductive substance and the electroless plating film using the solution containing the fine metal body, the solution containing the fine metal body After immersing the object to be plated in it and depositing a fine metal body on it, rinse the fine metal body that does not adhere sufficiently to the surface of the object to be plated with water and immerse it in the electroless plating solution to surface the object to be plated. The plating film is deposited on.

[Operation as a basic principle]

It is well known that one of the features of the fine metal body of the present invention is that the proportion of the surface area per mass increases as the body becomes finer.

By utilizing this relationship between the mass and the surface area, by attaching a fine metal body to the object to be plated, the surface of the plastic is covered with a fine metal body, even though it is actually plastic, and the surface of the object to be plated is a kind of It becomes similar to a metal, and by using the autocatalytic property of the plating bath to cause a plating deposition reaction, a metal plating film is obtained on the object to be plated with an action that is fundamentally different from the catalytic effect using ordinary palladium. It is possible.

[Example 1] 30 g of nickel sulfate hexahydrate and 3 g of gelatin are dissolved in distilled water 1, and 200 ml of a solution in which 25 g / sodium borohydride is dissolved while stirring well is added to the stirring aqueous solution. The metal salt was gradually added to carry out a reduction treatment, and 30 g of sodium hypophosphite was added as a stabilizer to a solution containing fine metal bodies subjected to the reduction treatment, and then sulfuric acid was added to adjust the pH to 1. After that, the etched ABS resin is dipped in a solution containing a fine metal body, adhered and washed with water, and nickel sulfate 26, which is generally well known, is used.
g /, sodium acetate 26g /, sodium citrate
15g /, sodium hypophosphite 16g /, thiourea 3
It is immersed in an electroless nickel plating solution under the composition conditions of ppm, temperature 90 ° C. and pH = 5.0 to deposit a nickel plating film on the ABS resin surface. When immersed in an electroless nickel plating solution for 1 hour, a nickel plating film of about 17 μm could be obtained.

[Example: 2] 10 g of nickel chloride hexahydrate and 1 g of gelatin were added to distilled water 1
100 g of a solution of sodium borohydride (30 g / mol) was gradually added to the stirred aqueous solution to carry out a reduction treatment to prepare a solution containing fine metal bodies. After that, a stabilizer was added, and nickel plating was performed using the ABS resin etched as in Example 1 above.

[Example: 3] 20 g of cobalt (II) sulfate heptahydrate and 5 g of gelatin,
Dissolve in distilled water 1 and add 100 ml of a solution containing 40 g / sodium borohydride while stirring well to the above stirred aqueous solution to carry out a reduction treatment to produce a solution containing fine metal bodies. After that, 30 g of sodium hypophosphite and 20 g of sodium acetate as a complexing agent are dissolved and put in a solution containing fine metal bodies, and then adjusted to pH = 10 with sodium hydroxide.

The etched ABS resin can be immersed in a solution containing a fine metal body, adhered to the surface of the ABS resin and washed with water, and then a cobalt plating film can be obtained in an electroless cobalt plating bath.

The composition of the cobalt plating bath is 20 g of cobalt sulfate heptahydrate.
/, Sodium hypophosphite 21 g /, sodium tartrate 115 g /, boric acid 30 g /, pH = 9.0. When immersed in an electroless cobalt plating solution for 1 hour, a 13 μ cobalt plating film could be obtained.

[Example 4] 15 g of copper (II) sulfate dihydrate and 1 g of gelatin were dissolved in 1 of distilled water and stirred while stirring with sodium borohydride 10
A 400 ml aqueous solution in which g / is dissolved is gradually added to the stirred aqueous solution to carry out a reduction treatment to produce a fine metal body. 30 g of sodium hypophosphite was added as a stabilizer for the solution containing the produced fine metal body, and the etched ABS resin was immersed in the fine metal body solution and washed with water to adhere to the ABS resin surface. To obtain a copper plating film in an electroless copper plating solution.

The composition of the electroless copper plating solution is a bath composition of copper sulfate 10 g /, ethylenediamine tetraacetic acid disodium 30 g /, formaldehyde (37%), 3 ml /, bipyridyl, a little polyethylene glycol, pH = 12.2, and a temperature of 70 ° C. did.

When immersed in electroless copper plating solution for 1 hour, 2.
It was possible to obtain a copper plating film of 2μ.

〔The invention's effect〕

Since the present invention is configured as described above, it has various effects as described below.

According to the method of the present invention, a solution containing a fine metal body of the same metal as the type of the electroless plating bath can be used for the non-conductive substance and the object to be plated in which the deposition reaction of the electroless plating does not easily occur, Unwanted dissimilar metals can be prevented from mixing in the electroless plating bath, and the risk of self-decomposition of the electroless plating solution can be reduced. It can also be manufactured at a cost that is about 30% cheaper than using conventional tin-palladium catalysts. Furthermore, regarding the conditions for stabilizing the fine metal body in the solution, which was the biggest problem in practical use, the solution containing the fine metal body was stabilized by adding sodium hypophosphite and dimethylamine borane while adjusting. It can be used in any condition. In addition, since there is no recovery of precious metal catalysts or the use of aqueous hydrochloric acid containing tin, which is usually done, the effect of reducing the product price by simplifying the work process is great,
Since no precious metal catalyst is used, the production cost can be suppressed, the metal salt concentration can be easily increased, and the fine metal particles that adhere to the surface of the object to be plated can be increased to speed up the deposition rate. The coating adhesion is not inferior to conventional catalysts.

Since the composition of the electroless plating bath and the composition for obtaining a solution containing a fine metal body in the examples are almost the same, it is not difficult to obtain a similar catalyst in the use of various plating waste liquids generated in the plating operation process. .

Effects can be expected from the effective use of resources.

Claims (6)

[Claims] 1. A complexing agent when a dispersant is put in an aqueous solution containing nickel ions, cobalt ions, or copper ions, reduced by a reducing agent, and then a stabilizer is added, and the pH is adjusted to an alkaline side. A method for producing a solution containing a fine metal body used in electroless plating, which comprises: 2. The method according to claim 1, wherein the dispersant is gelatin or a surfactant. 3. The method according to claim 1, wherein the complexing agent is a monocarboxylic acid, a dicarboxylic acid, an oxycarboxylic acid or a carboxylic acid salt. 4. The method according to claim 1, wherein the reducing agent is sodium borohydride, potassium borohydride or dimethylamine borane. 5. The method according to claim 1, wherein the stabilizer is sodium hypophosphite or dimethylamine borane. 6. The method according to claim 1, wherein the pH of the solution containing the fine metal body is adjusted to 1 to 10 depending on the surface condition of the object to be plated.