JPH0757908B2 - Pretreatment agent for electroless plating and pretreatment method for electroless plating - Google Patents

Description

TECHNICAL FIELD The present invention relates to electroless plating for shielding electromagnetic waves from non-conductive substances, and more particularly to a pretreatment agent and a pretreatment method therefor.

[Prior Art] Various plating methods for plating an electrically non-conductive substance such as a synthetic resin article of this kind have been developed, and they have been used for various products in various fields. The method is commonly used.

In this electroless plating method, a pretreatment is applied to form a pretreatment layer coating film, and as a pretreatment agent that has been used to form the pretreatment layer coating film, in most cases, Many organic binders contained a large amount of metal particles.

Specifically, there is known, for example, US Pat. No. 4,663,240, which is related to the published patent publication No. 500344, 1987.

As described above, the reason why these pretreatment layer coating films are conductive and contain a metal is that the metal layer is formed on the basis of metal deposition by substitution of metal ions in the electroless plating method. is there.

[Problems to be Solved by the Invention] In the case of electroless plating, the pretreatment layer coating film formed as described above is subjected to alkali etching treatment, and then ordinary electroless plating is performed. There was a risk that the metal inside would leak out and cause pollution, and we had to focus on this measure as well.

The present invention has been developed in view of the above matters, and provides a pretreatment agent and a pretreatment method which are free from fear of pollution, easy to treat, and have high adhesion reliability between the plating layer and the pretreatment layer coating film. This is the purpose.

[Means for Solving the Problems] In order to achieve the above object, in the pretreatment agent for electroless plating of the present invention, the average particle size is 2 to 10 μm aluminum silicate particles and the silica-based compound having a particle size of 0.01 to 0.1 μm. The sol is a coating based on an acidic acrylic copolymer, and the solid content weight ratio of aluminum silicate and silica compound sol is 1:
In the pretreatment method for electroless plating, the pre-treatment method for electroless plating is applied to the desired location on the base of the product made of an electrically non-conductive material such as synthetic resin glass fiber or ceramic. A coating film made of a pretreatment agent for electrolytic plating is formed.

[Function] The pretreatment layer coating film formed by the above electroless plating pretreatment agent contains aluminum silicate particles, and since these aluminum silicate particles are so-called baked kaolin obtained by refining kaolin minerals. Since the hydrophilic and surface is porous, the silica-based compound sol having irregularities is also hydrophilic and is supported on the irregularities of the surface of the aluminum silicate particles, and the acrylic copolymer coating is hydrophilic and acidic. Therefore, a hydrophilic coating film exists on the surface of the non-conductive substance.

Then, the silica gel produced from the silica-based compound sol by performing a normal etching treatment is retained on the surface of the aluminum silicate particles in a porous state having hydrophilicity and surface activity, and is exposed on the surface of the coating film. Since the coating film contains no metal, there is no risk of pollution occurring during the etching process.

Then, the active sites of the metal are formed on the surface of the coating film by the usual method for the metal ion substitution of the electroless plating, but the surface of the coating film after the etching treatment is neutral or acidic and hydrophilic, and the formation of ordinary active sites is performed. Since the aqueous hydrochloric acid solution of palladium chloride used for is acidic, both of them adapt well without change, and palladium ions are strongly adsorbed on the irregularities of the porous surface of the silica gel on the surface of the coating film.

Also in the next electroless plating, since the coating film is hydrophilic, it is well compatible with the plating solution, and the plating solution satisfactorily penetrates into the irregularities of the porous surface of silica gel and the surface of aluminum silicate particles. Ion substitution is performed to form a stable metal layer with good adhesion.

[Examples] Next, examples of the present invention will be described.

A calcined kaolin powder having an average particle diameter of 5 μm (calcined kaolin powder in this state is a commercially available size) and SiO ₂ particles having a particle diameter of 0.01 to 0.1 μm were dispersed in an organic solvent in a colloidal state. A pretreatment agent for electroless plating is obtained by incorporating an organosilica sol into a coating material having an acidic acrylic copolymer as a base.

The weight ratio of aluminum silicate powder and organosilica sol contained in the acrylic copolymer paint is preferably 1: 1 to 10: 1 (solid content ratio), and the content of both substances in the coating film is 30 to 90%.
Is the best.

The above-mentioned pretreatment agent is spray-painted on a desired portion of a product made of an electrically non-conductive substance by spraying, and dried to form a pretreatment layer coating film, which is then subjected to etching treatment with an aqueous sodium hydroxide solution and then washed with water. , An aqueous solution of palladium chloride and hydrochloric acid, activated by an aqueous solution of stannic chloride and hydrochloric acid, and subjected to ordinary electroless copper plating for reducing copper ions to form a copper film.

The formed pretreatment layer coating film is acidic and rich in hydrophilicity, and the plating solution easily penetrates to the inside. Therefore, the adhesion of the plating layer is good, there is no fear of pollution, and good quality plating can be performed. is there.

EFFECTS OF THE INVENTION According to the present invention, a pretreatment layer coating film having extremely good hydrophilicity can be formed on the surface of a non-conductive substance, and the surface is formed in a porous or uneven shape. , The plating solution penetrates into the details to form a stable metal layer with good adhesion, and the coating film is acidic,
The effects are that electroless plating can be performed easily, there is no fear of pollution, and extremely safe processing is possible.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaru Kusano 1-43 Dainichi-cho, Moriguchi City, Osaka Prefecture Daiho Kogyo Co., Ltd. (72) Inventor Takuhisa Fujita 761-1 Katsuma Katsuta-cho, Katsuta-gun, Okayama (56) References JP-A-51-126932 (JP, A)

Claims (2)

[Claims] 1. A paint based on an acidic acrylic copolymer containing aluminum silicate particles having an average particle diameter of 2 to 10 μm and silica compound sol having a particle diameter of 0.01 to 0.1 μm as a base material. The solid content weight ratio of the compound sol is 1:
A pretreatment agent for electroless plating, which is contained at a ratio of 1 to 10: 1. 2. An aluminum silicate particle having an average particle diameter of 2 to 10 μm and a silica-based compound sol having a particle diameter of 0.01 to 0.1 μm are placed at a desired location on a base made of an electrically non-conductive substance, in a solid content weight ratio of 1. A pretreatment method for electroless plating, which comprises forming a coating film made of a coating material containing an acrylic copolymer as a base material in an amount of 1 to 10: 1.