JP2000236161A - Manufacturing method of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a printed wiring board which is high in accuracy and reliability by a method, wherein a catalyst such as palladium left on the surface of an insulating layer is inactivated, preventing a trouble such as a constricted part or a bridge from being formed on a circuit pattern for improving it in insulating properties in a method of manufacturing a printed wiring board through an additive method, where a circuit pattern is formed of a copper plating layer formed on the surface of an insulating layer. SOLUTION: After a circuit pattern is formed, a board is dipped into an alklbenzimidazole solution, an alkylbenzimidazole protective film is formed around a circuit pattern with respect to a sulfide compound, the board is dipped into a palladium deactivation processing solution whose main component is a sulfide compound, by which palladium as a catalyst is deactivated, and furthermore the board is dipped into a hydrochloric acid, by which an alkylbenzimidazole film serving as a protective film for a circuit pattern is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board, in which a palladium catalyst is applied to the surface of an insulating layer, and then copper plating is performed to form a circuit pattern on the copper plating layer.

[0002]

2. Description of the Related Art Conventionally, copper plating is applied to the surface of an insulating layer,
An additive method for forming a circuit pattern using the copper plating layer is known. Also, the inventors have filed Japanese Patent Application No.
No. 218504 discloses a palladium inactivation treatment liquid for inactivating palladium as a catalyst remaining in an insulating layer, and a method for manufacturing a printed wiring board using the treatment liquid.

[0003]

[Problems to be Solved by the Invention] Japanese Patent Application No. 10-2185
According to the method presented in No. 04, when palladium as a catalyst remaining in the insulating layer is deactivated by sulfide with a palladium deactivation treatment liquid, copper forming a circuit pattern at this time also contains palladium. It is sulfided by the passivation solution to produce copper sulfide. This copper sulfide causes a problem in insulation and the like.

[0004] Therefore, the copper sulfide generated here must be removed. As a method of removing copper sulfide, there are a polishing method of physically removing copper sulfide by polishing, and a dissolving method of dissolving copper under the generated copper sulfide film and removing it together with the copper sulfide film. is there. However, in the polishing method, copper sulfide generated on the side surface of the circuit pattern or the concave portion of the circuit pattern cannot be polished, that is, cannot be removed. In addition, it is very difficult to uniformly dissolve copper in the melting method, and thinning and disconnection often occur in a circuit pattern.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and when palladium as a catalyst remaining in an insulating layer is converted into sulfide by a palladium deactivation treatment liquid to deactivate the catalyst,
An object of the present invention is to provide a method for manufacturing a printed wiring board, in which copper forming a circuit pattern does not sulfide, that is, copper sulfide is not generated.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a printed wiring board by an additive method of forming a circuit pattern by a plating layer formed on a surface of an insulating layer,
After forming the circuit pattern, the substrate on which the circuit pattern is formed is immersed in a solution of alkylbenzimidazole, and at least the surface of the circuit pattern is covered with a film of alkylbenzimidazole, and then a palladium deactivation treatment liquid The substrate is immersed in the catalyst, palladium serving as a catalyst is sulfided and inactivated, and then, the substrate is immersed in hydrochloric acid to remove the alkylbenzimidazole covering the surface of the circuit pattern. To achieve.

[0007]

FIG. 1 is a process flow showing an embodiment of the present invention. An embodiment of the present invention will be described with reference to FIG. First, palladium as a catalyst is applied to the surfaces of the insulators on both sides of the substrate, electroless copper plating is performed, and further electrolytic copper plating is performed to obtain a copper plating layer. Subsequently, an etching resist is formed on the copper plating layer in a pattern in which a circuit is to be formed, etching is performed, and after etching, the etching resist is removed to obtain a desired circuit pattern (see FIG. 1). Step S0). This step will be described in detail with reference to FIG.

First, a substrate 10 is made (FIG. 2A). In the substrate 10, circuit patterns of a second layer 14 and a third layer 16 serving as core layers are formed on both surfaces of the insulating plate 12, and other insulating layers 18 and 18 are laminated or coated with an insulating resin on both surfaces. Things. Next, the stannic ion is immersed in a palladium colloid solution in which a protective colloid is formed around the palladium metal, so that the substrate 10 is provided with palladium 20 as a catalyst (FIG. 2B). continue,
This substrate 10 is immersed in an electroless copper plating bath, and is further subjected to electrolytic copper plating to form a copper plating layer 22 having a predetermined thickness (FIG. 2C). Next, for the copper plating layer 22,
A circuit is formed by a photographic method or a printing method, that is, an etching resist is formed along a circuit pattern and etching is performed. Then, when the etching resist is removed, a circuit pattern 24 is obtained. However, as a result, the palladium 20 remains on the surface of the insulating layer 18 that has appeared on the surface (FIG. 2D).

Referring back to FIG. 1, the result of step S0 in FIG. 1 is that the circuit pattern is certainly formed as shown in FIG. The catalyst palladium still remains on the surface. Subsequently, the process proceeds to step S1 in FIG.
Immerse in a solution of alkylbenzimidazole at 5 ° C for 2-3 minutes. As a result, a protective coating of alkylbenzimidazole is formed on the circuit pattern. Naturally, a film is formed on palladium, but it can sufficiently react with the palladium inactivating solution. On the other hand, the coating of the circuit pattern against copper has a strong protecting power and does not combine with the palladium inactivating solution to form sulfide. Next, the substrate is washed with water to remove excess alkylbenzimidazole (step S2). Subsequently, the substrate is immersed in a palladium deactivating solution, which is a mixed solution of aqueous ammonia and sodium sulfide, for about 1 minute (step S3), pulled up, washed with water, and rinsed out of the attached processing liquid (step S4). . At the end, the substrate is immersed in 1N (regulated) hydrochloric acid (inorganic acid or organic acid) at room temperature for about 1 minute to remove the alkylbenzimidazole covering the copper of the circuit pattern (Step S5). The substrate is washed with water to completely remove the hydrochloric acid remaining on the substrate (Step S6). In this embodiment, the substrate 10 having four layers of circuits is used.
The present invention is not limited to this.

[0010]

According to the present invention, after the circuit pattern is protected from alkylation with alkylbenzimidazole, the catalyst is deactivated by sulfided palladium, and after the inactivation treatment of palladium, Since the alkylbenzimidazole which is a protective film from sulfide formation of the copper pattern is removed, no copper sulfate is generated. Therefore, there is no need to remove copper sulfate, and there is no thinning or disconnection of wiring due to removal of copper sulfate. For this reason, a printed wiring board with high definition and high reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a process flow showing one embodiment of the present invention.

FIG. 2 is a diagram showing steps of copper plating to circuit pattern formation on a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 12, 18 Insulating layer 14, 16 Inner layer (2nd, 3rd layer) circuit pattern 20 Palladium (catalyst) 22 Copper plating layer 24 Outer layer circuit pattern

Claims (1)

[Claims] In a method for manufacturing a printed wiring board by an additive method, wherein a circuit pattern is formed by forming a plating layer on a surface of an insulating layer using palladium as a catalyst and forming the plating layer, after forming the circuit pattern, Immerse the substrate on which the circuit pattern is formed in a solution of alkylbenzimidazole, cover at least the surface of the circuit pattern with a film of alkylbenzimidazole, and then immerse the substrate in a palladium deactivation treatment liquid,
A method for manufacturing a printed wiring board, comprising: inactivating palladium, which is a catalyst, by sulphidizing it; and thereafter immersing the substrate in hydrochloric acid to remove the alkylbenzimidazole covering the surface of the circuit pattern.