JPH0337878B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to printed wiring boards for producing single-sided printed wiring boards, double-sided printed wiring boards, multilayer printed wiring boards, flexible wiring boards, etc. using a chemical plating method. More specifically, the present invention relates to a method of manufacturing a printed wiring board using an additive method in which conductor circuits are formed by electroless plating.

[Conventional technology]

Conventionally, conductor circuits on printed circuit boards have been formed by etching, electrolytic plating, or the like. Specifically, the formation of a conductor circuit using this etching method involves providing an ink resist on the non-etched portions of the metal conductor layered on the printed circuit board by screen or offset printing, or providing a cured film layer of photosensitive resin. This method then forms a conductor circuit by etching unnecessary portions and removing the resist and the like from non-etched portions. According to this method, since the metal conductor is removed by etching, it is not resource-saving and has the drawback that it requires a large number of steps because it requires the formation and removal of a resist and the like. In addition, the electrolytic plating method involves applying a hardened layer of ink resist and photosensitive resin to the non-plated portions of a conductive substrate, applying electrolytic plating to form a conductive circuit, and then transferring this conductive circuit onto a predetermined insulating substrate. However, this method is a very complicated process.

On the other hand, in order to solve the drawbacks of the above two methods, there is an additive method in which a conductor circuit is formed by electroless plating. Commonly used for this purpose are the CC-4 method and the PSMD method. In the CC-4 method, an adhesive layer with plating catalytic properties is formed on an insulating substrate, and a hardened layer such as resist is provided on the non-plated parts. A conductor circuit is formed by electroless plating. Also, PSMD
The method (Photo Selective Metal Deposition) involves forming a plating catalyst layer on an insulating substrate, irradiating the non-plated parts with ultraviolet rays, and decatalyzing the plating catalyst layer corresponding to that part with the ultraviolet rays.
Electroless plating is applied to form a conductor circuit.

[Problem that the invention seeks to solve]

The present invention is an improvement of the additive method of forming conductor circuits by electroless plating.

In the CC-4 method, an adhesive layer is formed on the substrate,
There is an inconvenience in that it requires the formation of a resist, etc. on top of that, and although the formation of a resist, etc. can be omitted in the PSMD method, it is a difficult manufacturing method in which a conductor circuit is formed after ultraviolet treatment.

The present invention eliminates these drawbacks and at the same time provides a method for manufacturing printed wiring boards using a completely new additive method.

[Means for solving problems]

The manufacturing method of the present invention is to form a conductor circuit on an insulating substrate by electroless plating to manufacture a printed wiring board, and includes a first step of forming a plating catalyst layer on the surface of the substrate, and a first step of forming a plating catalyst layer on the surface of the substrate. a second step in which the catalyst layer of the non-conductor circuit portion on the surface of the substrate treated in the first step is decatalyzed by heat; and a second step in which the catalyst layer on the surface of the substrate treated in the second step is activated. and a fourth step of applying electroless plating to the surface of the substrate treated in the third step to form a desired conductor circuit.

The Metsuki catalyst layer is a commonly used palladium chloride-stannic chloride mixed complex solution (e.g.
HS101B, a product of Hitachi Chemical Co., Ltd.), and is formed by dipping the substrate in the above solution, or by applying or spraying the solution. By making the substrate surface uneven using an appropriate method prior to the above process,
The effect of forming the catalyst layer is further improved. Examples of this method include physical roughening methods such as honing treatment and chemical surface roughening methods using an oxidizing solution.

The method for decatalytizing the catalyst layer is to deactivate the catalyst layer corresponding to the non-conductive circuit portion by heat. For example, this can be carried out by contacting the part with a heating contact body. Examples of the heating contact body include metal plates, ceramic plates, and the like. Methods for heating metal plates include a method of incorporating a heater inside the metal plate, making the metal plate itself from a heat-generating resistance metal such as nichrome, or indirectly heating the metal plate with infrared rays or the like.

As a method for activating the catalyst layer, a commonly used Metsuki catalyst activation solution (for example, a hydrofluoric acid-hydrochloric acid aqueous solution, commercially available is OPC-555 Accelerator, manufactured by Okuno Pharmaceutical Co., Ltd.). , by dipping the substrate in the above solution, or by applying or spraying the solution.

Examples of the electroless plating solution include electroless nickel plating solution and electroless copper plating solution.

Next, the method for manufacturing a printed wiring board according to the present invention will be explained based on the attached drawings. First, as shown in FIG. 1, the surface of a substrate 1 (which may include through holes, although not shown) A plating catalyst liquid is applied to the substrate by immersion or the like, and after washing with water, it is dried using an infrared light bulb or hot air to form a plating catalyst layer 2 (first step). Next, as shown in FIG. 2, a heated metal plate 3 having the same shape as the non-conductor circuit portion is brought into close contact with the plated catalyst layer 2, and that portion is made non-catalytic to form a non-catalytic layer 4 ( 2nd step).
Next, as shown in FIG. 3, an activation layer 5 is formed on the plating catalyst layer 2 of the conductor circuit portion by immersing the substrate in a plating catalyst activation solution (third step).
Next, when this is subjected to electroless plating using a normal method, a reduced plating metal 6 is deposited on the activation layer 5 as shown in FIG. 4 (fourth step), and the desired printed wiring board is formed. Manufactured.

If the drying temperature using an infrared light bulb or hot air in the first step is too high, the plating catalyst layer will become non-catalytic, so it is desirable to dry at a temperature of 60° C. or lower. Furthermore, if the temperature of the metal plate, etc. in the second step is too low, decatalyticization will not proceed, and there is a risk that the non-catalyzed layer will react with the activated layer during activation in the third step. If the temperature is too high, there is a risk of softening or melting the substrate, so a temperature of 100°C to 300°C, particularly 200°C, is desirable.
The time for close contact is appropriately determined depending on the temperature of the metal plate, the substrate material, etc., but is preferably 1 minute to 10 minutes.

The present invention will be specifically explained below using Examples.

Example A polyester film with a thickness of 200 μm was honed to obtain a substrate with a surface roughness of 2 μm. This substrate was immersed for 10 minutes at room temperature in a glazing catalyst solution obtained by mixing HS101B (product of Hitachi Chemical Co., Ltd.), concentrated hydrochloric acid, and water in a ratio of 1:5:10, and then washed with water for 1 to 2 minutes. Then, it was completely dried with hot air at 50°C to obtain a plated catalyst layer. On this surface, chrome plating is applied to a steel plate approximately 10 m/m thick, with the non-conductor circuit part protruding 5 m/m from the conductor circuit part.
A non-catalytic metal plate with a thickness of 10 μm and a temperature of 200°C is placed in close contact with the plate for 1 minute. Next, the above substrate was immersed in a 20% by volume aqueous solution of OPC-555 Accelerator (manufactured by Okuno Pharmaceutical Co., Ltd.) for 3 minutes at room temperature.
When electroless nickel plating was applied by immersing S680 (nickel sulfate-sodium hypophosphite system, Nippon Kanigen Co., Ltd. product) in a 20% by volume aqueous solution at 70°C for 10 minutes,
A flexible printed wiring board made of nickel metal was obtained.

In the above embodiment, an example was given of a flexible printed wiring board, but it can also be applied to all other printed wiring boards, and can also be applied not only to polyester films but also to other substrates, such as polycarbonate substrates, glass epoxy substrates, etc. Needless to say.

〔Effect of the invention〕

As described above, according to the present invention, the plating catalyst layer is decatalyzed by heat and a printed wiring board is manufactured by electroless plating, which is a relatively simple process.
Moreover, it does not require etching, resist formation, or peeling, and is highly effective as a method for manufacturing printed wiring boards in large quantities at low cost. Furthermore, when a flexible printed wiring board is manufactured by the manufacturing method of the present invention, continuous hoop manufacturing is also possible by using a strip-shaped plastic film as the substrate.

[Brief explanation of the drawing]

1 to 4 are partially enlarged views of successive steps showing the steps of the manufacturing method of the present invention. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Plating catalyst layer, 3... Heated metal plate, 4... Non-catalyzed layer, 5... Activation layer, 6... Electroless plating metal. However, the thickness of each layer is appropriately enlarged for explanation.

Claims (1)

[Claims] 1. A method for manufacturing a printed wiring board by forming a conductor circuit by electroless plating on an insulating substrate, the method comprising: forming a plating catalyst layer on the surface of the insulating substrate (hereinafter referred to as the substrate); a first step of forming the catalyst layer; a second step of thermally decatalyzing the catalyst layer of the non-conductor circuit portion on the surface of the substrate treated in the first step;
a third step of activating the catalyst layer of the substrate treated in the second step; and a third step of applying electroless plating to the surface of the substrate treated in the third step to form a desired conductor circuit. A method for manufacturing a printed wiring board characterized by comprising four steps. 2. The method of manufacturing a printed wiring board according to claim 1, wherein the decatalytic treatment in the second step is performed by contacting a heating contact member with a catalyst layer of a non-conducting circuit portion.