JPH0293076A - Production of fine metal body utilized for electroless plating - Google Patents

Abstract

PURPOSE:To produce fine metal bodies utilized for electroless plating as a substitute for a catalyst by simple operation by adding a dispersant and a complexing agent to an aq. metallic salt soln., reducing the salt with a reducing agent and further adding a stabilizer. CONSTITUTION:A dispersant such as gelatin and a complexing agent such as monocarboxylic acid are added to an aq. metallic salt soln. contg. ions of Ni, Co, Cu, etc. An aq. soln. of a reducing agent such as sodium borohydride is poured while stirring to reduce the metallic salt and a stabilizer such as sodium hypochlorite is further added to the soln. contg. fine metal bodies formed by the reduction. A product to be plated is immersed in the soln. contg. the metal bodies to stick the metal bodies and plating is deposited on the product by immersion in an electroless plating soln. The fine metal bodies are used in the case of an electrically nonconductive material and a product on which a deposition reaction by electroless plating does not easily take place.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing fine metal bodies used in electroless plating using nickel, cobalt, copper ions, etc.

[Conventional technology]

Conventionally, a widely used method for electroless plating for non-conductive substances and objects to which electroless plating precipitation reactions do not easily occur is to place the object to be plated in a hydrochloric acid solution of stannous chloride. It is immersed in a solution of palladium chloride in hydrochloric acid to bond with stannous ions, which have a strong reducing power, and then immersed in a hydrochloric acid solution of palladium chloride to deposit palladium nuclei on the surface of the plated object through a redox reaction. Using the palladium nuclei as a catalyst, electroless plating is performed. The method for obtaining a plated film is well known. Several other methods using palladium and tin colloids are also known.

(Publication Patent Publication No. 1986-207667, 1983-18
(No. 6480) However, since these methods use noble metals as the core, they have the disadvantage that the noble metal catalyst that is separated from the object to be plated in the electroless plating solution becomes a major factor in the self-decomposition of the electroless plating solution. Furthermore, since the catalyst is a noble metal, there is a drawback that the cost involved in the process of applying the catalyst is large in the production cost. Furthermore, the method of using a stannous chloride hydrochloric acid solution has the disadvantage of damaging the surface of objects to be plated that are sensitive to acids and hydrochloric acid.

[Problem that the invention seeks to solve]

Conventional electroless plating catalysts use precious metal catalysts, so there are problems such as self-decomposition of the electroless plating solution due to the contamination of precious metal catalysts, increased production costs due to the use of precious metal catalysts, and the surface of the object to be plated containing precious metal catalysts. However, the present invention overcomes these problems and provides a simple and easy-to-use alternative to precious metal catalysts.
The present invention aims to provide a method for producing fine metal bodies that can be used as a substitute for catalysts used in electroless plating, which can be produced in large quantities at low cost, and is advantageous for industrial implementation. .

[Means for Solving the Problems] In order to achieve the above object, the present invention has conducted intensive research on electroless plating, and as a result, the present invention has solved the above problems without using a precious metal catalyst for the first time. It was discovered that by reducing nickel, cobalt, and copper ions, they can be used as catalyst substitutes for electroless plating, and based on this knowledge, the present invention was developed. In the present invention, an aqueous solution containing nickel, cobalt, and copper ions is reduced with a reducing agent to generate fine metal bodies, which are then used as a substitute for an electroless plating catalyst.

In order to obtain a metal salt aqueous solution in the present invention, a water-soluble metal salt compound is used as a solvent.

Typical examples include nickel (II) acetate tetrahydrate, nickel (II) sulfate ammonium hexahydrate,
Nickel carbonate (n) ・tetrahydrate, nickel chloride (I
I) - Hexahydrate, nickel (II) sulfate - Hexahydrate, cobalt acetate (■) - Tetrahydrate, cobalt (If
) ammonium hexahydrate, cobalt(II) chloride
・Hexahydrate, &tlW ammonium cobalt (n)
・Hexahydrate, cobalt phosphate octahydrate, cobalt sulfate l-(II) ・7hydrate, copper(II) acetate monohydrate, copper hydrochloride (n) ・dihydrate, chloride Niammonium copper (If) dihydrate, copper (II) phosphate trihydrate,
Potassium copper (n) chloride dihydrate, copper (II) sulfate
- Pentahydrate, nickel (II) chloride, nickel sulfate (■), copper chloride (■), copper sulfate (■), cobalt (II) chloride, '6AM cobalt (II), etc.

Reduction treatment is performed by using the chemicals used as reducing agents, such as sodium borohydride, potassium borohydride, and dimethylamine borane.

In order to disperse fine metal bodies in an aqueous solution, it is necessary to mix a dispersant into the aqueous solution containing metal ions and stir it before performing the reduction treatment.

Gelatin is used as a dispersant, and surfactants and the like are added depending on the purpose. Gelatin is usually sufficient, but
When using a surfactant, it is preferable to use an ionizable surfactant. The aqueous solution is adjusted using a dispersant so that the fine metal bodies are dispersed and easily adhere to the object to be plated.

In addition, in order to prevent the fine metal bodies generated by the reduction treatment from returning to ions, IO~40g of dimethylamine borane or sodium hypophosphite is added as a stabilizer to the solution containing the fine metal bodies. /l and always maintain a state in which a slow reduction reaction occurs in the solution to stabilize the presence of fine metal bodies.

It is also possible to change the pH of the solution containing fine metal bodies within the range of 1 to 10 depending on the surface condition of the object to be plated. When changing the pH, after adding the complexing agent, It is used after adding an acidic aqueous solution such as sulfuric acid or hydrochloric acid or an alkaline substance such as sodium hydroxide to change the pH value so as not to damage the surface condition of the object to be plated. When adjusting the pH, add a complexing agent to prevent the formation of hydroxides.

As complexing agents, monocarboxylic acids, dicarboxylic acids, oxycarboxylic acids, and carboxylic acid salts are used. As a typical example, 10 to 50 g/l of benzoic acid, succinic acid, lactic acid, sodium acetate, etc. are added to prevent the formation of hydroxide using a complexing agent, and then the pH is adjusted before use.

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

In this way, the above-mentioned reagents are used to produce fine metal bodies that can be used as catalyst substitutes for electroless plating.

The metal salt is dissolved in the solvent in the range 5-50 g/f, the dispersant is 1-10 g//! The metal ions are reduced while stirring.

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

For objects to be plated that use fine metal objects manufactured by the above procedure and do not allow easy deposition of non-conductive substances and electroless plated coatings, After dipping the plated object and attaching fine metal objects,
Fine metal bodies that are not sufficiently adhered to the surface of the object to be plated are washed away with water, and then immersed in an electroless plating solution to deposit a plating film on the surface of the object to be plated.

[Function as a basic principle]

It is well known that one of the characteristics of the fine metal body of the present invention is that the surface area ratio of a fine body to light increases.

Utilizing this relationship between mass and surface area, by attaching fine metal objects to the object to be plated, the surface of the plastic is covered with fine metal objects even though it is actually plastic, and the surface of the object to be plated becomes a kind of It is similar to metal, and it is possible to obtain a metal plating film on the object to be plated with an effect fundamentally different from the catalytic effect using ordinary palladium.

[Example = 1] 30g of nickel sulfate hexahydrate and 3g of gelatin were dissolved in 1j2 of distilled water, and while stirring well, 200ml of a solution was prepared by dissolving 25g/f of sodium borohydride! is gradually added to the stirring aqueous solution to reduce the metal salt, and in the solution containing the reduced fine metal bodies,
After adding 30 g of sodium hypophosphite as a stabilizer, adding sulfuric acid and adjusting the pH to 1, the etched ABS resin was immersed in a solution containing fine metal bodies.
It is generally well known that it is applied and washed with water.
Nickel sulfate 26 g/f, sodium acetate 26
Ro/! , Sodium citrate 15g/L Sodium hypophosphite 16g/L Thiourea 3ppm, Temperature 90°C
A nickel plating film is deposited on the ABS resin surface by immersing it in an electroless nickel plating solution under the composition condition of -PH content of 5.0. When it was immersed in an electroless nickel plating solution for 1 hour, a nickel plating film of about 17μ could be obtained.

[Example: 2] 10 g of nickel chloride hexahydrate and 1 g of gelatin in distilled water
1, and while stirring thoroughly, 100 ml of a solution containing 30 g/l of sodium borohydride was gradually added to the aqueous solution being stirred to perform a reduction treatment,
After producing a fine metal body, a stabilizer was added and nickel plating was performed using etched ABS resin in the same manner as in Example 1 above.

[Example: 3] Kobal sulfate l-(II) - 20 g of heptahydrate and 5 g of gelatin were dissolved in 11 parts of distilled water, and 40 g/l of sodium borohydride was dissolved while stirring well. &1
The above water being stirred at 00mf? After gradually adding it to the solution and performing reduction treatment to produce a fine metal body, dissolve 30 g of sodium hypophosphite and 20 g of sodium acetate as a complexing agent, add it to the fine metal body, and add water. Adjust the pH to 10 with sodium oxide.

After the etched ABS resin is immersed in a fine metal solution to adhere to the ABS resin surface and washed with water, a cobalt plating film can be obtained in an electroless cobalt plating bath.

The composition of the cobalt plating bath is cobalt sulfate heptahydrate 20
g/f, sodium hypophosphite 21 g/f
, storium tartrate 115g/f, oxalic acid 30g/1.
．． Plating was performed with a bath composition of pH=9.0 and temperature of 90°C. When immersed in an electroless cobalt plating solution for 1 hour, a 13μ cobalt plating film could be obtained [Example = 4] 15g of copper (II) sulfate dihydrate and gelatin Ig.
is dissolved in 1j2 of distilled water, and while stirring, 400 m12 of an aqueous solution containing 10 g/f of sodium borohydride is gradually added to the stirred aqueous solution for reduction treatment to produce a fine metal body. . 30g of sodium hypophosphite as a stabilizer for the manufactured fine metal bodies
The etched ABS resin was immersed in a fine metal solution, washed with water, and adhered to the surface of the ABS resin to obtain a copper plating film in an electroless copper plating solution.

The composition of the electroless copper plating solution is copper sulfate 10 g/ff.
i, ethylenediaminetetraacetic acid disodium 30 g/
l, formaldehyde (37%) 3mf/f, some bipyridyl, some polyethylene glycol, PH=12.2
, a bath composition with a temperature of 70°C was used.

When immersed in electroless copper plating solution for 1 hour, 2
．． A copper plating film with a thickness of 2μ could be obtained.

[Effects of the Invention] Since the present invention is configured as described above, it has many effects as described below.

According to the method of the present invention, fine metal objects of the same type as the electroless plating bath can be used for non-conductive substances and objects to be plated in which the precipitation reaction of electroless plating does not easily occur.・It is possible to prevent unnecessary dissimilar metals from being mixed into the plating bath, reducing the risk of self-analysis of the electroless plating solution. It can also be produced at a cost approximately 30% cheaper than using conventional tin/palladium catalysts. Furthermore, the conditions for stabilizing fine metal bodies, which has been the biggest problem in practice, can be solved by adding sodium hypophosphite and dimethylamine borane while adjusting the conditions, so that fine metal bodies can be used in a stable state. Furthermore, since there is no need to recover precious metal catalysts or use an aqueous hydrochloric acid solution containing tin, which is usually done, the work process is simplified, which has a significant effect of reducing product prices. By increasing the metal salt concentration and increasing the number of fine metal bodies that adhere to the surface of the plated object, it is possible to accelerate the deposition rate, and the adhesion of the deposited plating film is also superior to that of conventional catalysts. There's nothing better or worse.

In addition, in the use of various plating waste liquids generated during the plating work process, the liquid composition of the electroless plating bath in the example and the liquid composition for obtaining fine metal bodies are almost the same to obtain a similar catalyst. It is not difficult to obtain metal objects from waste liquids.

The effects of the present invention can also be expected from the effective use of resources.

Procedural official document (spontaneous) November 28, 1999 Patent Office Ranking Officer Yoshi 1) Moon Takeshi 1, Indication of the case 1986 Patent side No. 246772 2 Name of the invention Fine particles used in electroless plating Method of manufacturing a metal body 3, Relationship with the case of the person making the amendment Patent applicant address Name: Sanko Special Metal Industry Co., Ltd. 4, Agent ■730 No. 082-221~38095, Date of amendment order Voluntary or more 7, Amendment Contents (1) The scope of claims starting from line 5 on page 1 of the specification is corrected as shown in the attached sheet. (Corrected part underlined (2)
) Delete from page 6 of the specification, line 6 "Usually..." to line 8 "It is better to use...".

(3) “10-40g” on page 6, line 14 of the specification is “3”
〜40g''.

(4) Page 8, line 20 of the specification: “Same as...
After J, insert "by causing a plating precipitation reaction using the autocatalytic properties of the plating bath."

(5) On page 12, line 18 of the specification, the phrase "self-analysis" is corrected to "self-decomposition."

Above [Attachment] 2. Claims (1) A dispersant and a complexing agent are added to an aqueous solution of a metal salt, and after reduction treatment with a reducing agent, a stabilizer is mixed and used for electroless plating. A method for manufacturing fine metal bodies.

(2) The method according to claim 1, wherein the metal salt aqueous solution is an aqueous solution containing nickel ions, cobalt ions, and copper ions.

(3) The method according to claim 1, wherein the dispersant is gelatin, a surfactant, or the like.

(4) The method according to claim 1, wherein the complexing agent is a monocarboxylic acid, a dicarboxylic acid, a monocarboxylic acid, or a carboxylic acid salt.

(5) The method according to claim 1, wherein the reducing agent is sodium borohydride or potassium borohydride 1 dimethylamine borane.

(6) The method according to claim 1, wherein the stabilizer is sodium hypophosphite or dimethylamine borane.

The method according to claim 1, wherein the liquid containing fine metal objects is adjusted to have a pH of 1 to 10 depending on the surface condition of the object.

Claims (7)

[Claims] (1) A method for producing fine metal objects used in electroless plating, in which a dispersant and a complexing agent are added to an aqueous solution of a metal salt, the mixture is reduced with a reducing agent, and then a stabilizer is mixed therein. (2) The method according to claim 1, wherein the metal salt aqueous solution is an aqueous solution containing nickel ions, cobalt ions, and copper ions. (3) The method according to claim 1, wherein the dispersant is gelatin or a nonionic surfactant. (4) 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. (5) The method according to claim 1, wherein the reducing agent is sodium borohydride, potassium borohydride, or dimethylamine borane. (6) The method according to claim 1, wherein the stabilizer is sodium hypophosphite or dimethylamine borane. (7) The method according to claim 1, wherein the pH of the solution containing fine metal bodies is adjusted to 1 to 10 depending on the surface condition of the object to be plated.