JPH046116B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to an insulating substrate whose surface is metallized and a method for manufacturing the same. [Background of the Invention] Conventionally, there is an electroless plating method as a method for metallizing the surface of an insulating substrate. One way to do this is to roughen the part of the surface of the insulating substrate that will be plated.
35-7732) and a method of plating after applying an acrylonitrile butadiene modified synthetic resin (adhesive) to the surface of an insulating substrate was developed (Japanese Patent Publication No. 39-15251). However, even with these methods, adhesion to the plating film was not sufficient, so methods of cleaning similar adhesives with chromium-sulfuric acid (Japanese Patent Publication No. 40-4393, Japanese Patent Publication No. 40-9664),
A method of treating chromium with sulfuric acid to generate carbonyl groups and carboxyl groups, and improving the anchoring effect on the surface and the adhesion with the plated film
9996), a method of making the adhesive surface a porous structure by treating it with chromium-sulfuric acid (Japanese Patent Publication No. 52-31539),
and a method of treating chromium with sulfuric acid or permanganate to generate carbonyl groups and making the surface of the adhesive microporous to improve its adhesion to the plating film (Japanese Patent Application Laid-open No. 15569/1983), etc. is proposed. In these methods, an adhesive is provided on the surface of an insulating substrate and the surface is treated with an oxidizing agent, such as chromium-sulfuric acid.If the oxidizing agent is new, it has a strong oxidizing power, so it decomposes and dissolves the rubber, causing the surface of the adhesive to be treated. It has a high ability to generate carbonyl groups and carboxyl groups and to make the surface porous or microporous. Therefore, the adhesion to the plating film is increased. However, on the other hand, when the treated area of the adhesive increases with this oxidizing agent, for example, in the case of a chromium-sulfuric acid oxidizing agent, Cr ³⁺ increases, and decomposition products and dissolved products of the rubber and resin components of the adhesive also accumulate. As a result, the oxidizing power gradually decreases, resulting in the formation of carbonyl groups and carboxyl groups, the inability to obtain surface porosity and microporosity, and the problem of reduced adhesion with the plated film. be. For this reason, conventional methods extend the life of the oxidizing agent by reducing Cr ³⁺ and returning it to Cr ⁶⁺ . could not be prevented. For this reason, in the conventional method, in addition to controlling the amounts of Cr ³⁺ and Cr ⁶⁺ , it was also necessary to control the treated area of the adhesive, and to renew the oxidizing agent when the specified treated area was reached. [Object of the Invention] The present invention has been made in view of the problems of the conventional methods described above, and relates to a method for preventing a decrease in adhesion to a plating film due to a decrease in the oxidizing power of an oxidizing agent. For this purpose, it is also provided that the adhesive surface treated with an oxidizing agent is given a new surface structure. [Summary of the Invention] To summarize the present invention, the present invention relates to a method for manufacturing an insulating substrate whose surface is metallized, and the present invention relates to a method for manufacturing an insulating substrate whose surface is metallized, and which includes a rubber, a filler, and a thermosetting resin as main components that decompose or dissolve in an oxidizing agent. a step of providing an adhesive composition layer on the surface of an insulating substrate, a step of treating the surface of the adhesive layer with an oxidizing agent to decompose or dissolve the rubber, filler, and thermosetting resin present near the surface; These decomposed products and dissolved products adhering to the adhesive layer are removed by washing with hot water at 50 to 100°C for 1 to 60 minutes, and the surface of the adhesive layer is removed from the recesses where the filler has been removed and the exposed protrusions of the rubber particles. and a step of attaching metal to a part or the entire surface of this surface by electroless plating. The greatest feature of the present invention is that even if the oxidizing power of the above-mentioned oxidizing agent decreases, the adhesion to the plating film does not decrease. In order to bring out this characteristic, the adhesive component provided on the surface of the insulating substrate is decomposed by an oxidizing agent.
In addition to conventional rubber (acrylonitrile butadiene rubber), this has been expanded to include fillers and thermosetting resins, and after applying this adhesive composition to an insulating substrate and curing, it is treated with an oxidizing agent such as chromium-sulfuric acid. After the treatment, the surface is washed with hot water. Of course, a vulcanizing agent and a vulcanizing aid may be added to the adhesive. With this method, the surface of the adhesive is different from the porosity or microporosity of the conventional method, and the concave portions where the filler is removed and the convex portions of the rubber particles exposed after the thermosetting resin is removed are uniform. A new structure was formed. The hot water washing performed in the present invention is particularly effective when the oxidizing agent has deteriorated. In other words, if the oxidizing agent is new, it is easy to obtain the above surface structure without hot water washing, but if the treated area of the adhesive increases, Cr ³⁺ increases and the decomposition products and dissolved products of the adhesive components increase. The accumulation of ions makes it difficult to obtain the surface structure. If hot water washing is performed at this time, decomposed products on the surface of the adhesive will be removed, and a surface structure almost the same as that obtained when treated with a fresh oxidizing agent will be obtained. Therefore, by performing hot water washing, the life of the oxidizing agent (the treated area of the adhesive) can be extended by approximately 2.7 times. That is, even if the oxidizing agent deteriorates, hot water washing prevents the adhesion of the plating film from decreasing. One of the reasons for this is that the surface structure of the adhesive of the present invention after treatment with an oxidizing agent and hot water washing is not porous or microporous as in the prior art, but has a structure in which concave portions and convex portions are uniformly formed. It is possible that it has become. As mentioned above, hot water washing is effective when the oxidizing agent has deteriorated, but industrially it is recommended to perform the process after the oxidizing agent treatment step so that the oxidizing agent can be treated even if it is new. can. The adhesive components used in the present invention include, for example, rubber (acrylonitrile butadiene rubber) that decomposes into Cr ⁶⁺ , which is an oxide of the oxidizing agent, and filler (carbonate, silica, etc.) that decomposes and dissolves in sulfuric acid, which is the solvent of the oxidizing agent. The main components are a fine powder such as Other ingredients include fine sulfur powder as a vulcanizing agent and zinc oxide as a vulcanizing aid. The above-mentioned resol type phenolic resin is made from phenol, formalin, ammonia as a catalyst, and xylene as a reaction solvent, as it is easy to decompose with sulfuric acid even when Cr ³⁺ increases, and is easy to remove by washing with hot water afterwards. After condensation, neutralization, and water removal, hexamine is added as a hardening agent, and then xylene is removed while stirring, and the resulting product is used. The blending ratio of the above adhesive components is 40 to 70 parts of rubber, 10 to 30 parts of filler, and 30 to 30 parts of resol type phenolic resin.
Desirably 60 parts, 0.2 to 2.0 parts of vulcanizing agent, and 0.1 to 1.0 parts of vulcanization aid (parts by weight). When this mixture is applied to the surface of an insulating substrate, the mixture is dissolved and dispersed in a solvent by a coating means to change the viscosity. For example, in the curtain coating method, 100 to 400 cp (25
℃). 100-200P for roll coating method
(25℃), 100-400P for dip coat method
(25℃). This coating thickness is determined by the thickness after curing.
The gap and speed of the coating machine can be adjusted freely to achieve a coating thickness of 20 to 50 μm. In this way, the adhesive applied to the surface of the insulating substrate can be cured in 90 to 200 minutes at 150 to 180°C. Then,
This adhesive surface is treated with an oxidizing agent. As an oxidizing agent, chromium-sulfuric acid is preferable, and chromate 20~
Using 200g/, concentrated sulfuric acid 100~400ml/, 35~
Use at 60℃. Next, after washing with water, a hot water washing process is performed. Hot water washing conditions are 50-100°C for 1-60 minutes.
In the subsequent steps, the surface can be metallized by ordinary electroless plating pretreatment and electroless plating. This will become clear from the examples. [Examples of the Invention] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. Reference Example 1 Two types of adhesives shown in Table 1 below were prepared.

〔Effect of the invention〕

According to the present invention, the life of the oxidizing agent (adhesive treatment area) is extended by about 2.7 times, so a device for reducing Cr ³⁺ to Cr ⁶⁺ is not required. In addition, Cr ⁶⁺ in the oxidizing agent
It goes without saying that chromic anhydride, potassium dichromate, or sodium dichromate should be used while supplementing to always maintain a specified amount of chromic acid. Further, according to the present invention, a product with high adhesion between an insulating substrate and a plating film can be obtained, so the present invention can be utilized for manufacturing printed wiring boards. In other words, a method in which an adhesive is applied to an insulating substrate, electroless plating is applied to the entire surface, and parts other than the circuit are etched away to form a circuit. A method in which a circuit is formed by depositing a thick layer of plating and etching away the parts other than the circuit. A thin layer of electroless plating is applied to the entire surface, and then a plating resist is applied to areas other than the circuit forming area. A method of forming a circuit by depositing thickly by electrolytic plating, then removing the plating resist, and etching away the exposed thin electroless plated film, and
The present invention can be applied to a method of forming a circuit by providing a plating resist on an adhesive other than the circuit forming part and depositing plating on the circuit forming part only by electroless plating.

[Brief explanation of drawings]

Figure 1 is an SEM photograph of the particle structure of each adhesive surface after treatment with a new oxidizing agent in adhesive composition A according to the present invention and conventional adhesive composition B, and Figure 2 is a photograph of peeling with and without hot water washing treatment according to the present invention. A graph showing the relationship between strength and adhesive treatment area with oxidizing agent. Figure 3 shows the particle structure of each adhesive surface with and without hot water washing.
This is a SEM photo.

Claims (1)

[Claims] 1. A step of providing an adhesive composition layer on the surface of an insulating substrate, the adhesive composition layer mainly consisting of rubber, filler, and thermosetting resin that decomposes or dissolves in an oxidizing agent, and treating the surface of the adhesive layer with an oxidizing agent to remove the adhesive composition near the surface. The step of decomposing or dissolving the rubber, filler and thermosetting resin present on the surface is followed by removing these decomposed products and dissolved products adhering to the surface by washing with hot water at 50 to 100°C for 1 to 60 minutes. Steps of forming the surface of the adhesive layer into a structure having concave portions from which the filler has been removed and convex portions of exposed rubber particles, and attaching metal to part or the entire surface of this surface by electroless plating. A method for manufacturing an insulating substrate with a metalized surface, the method comprising: