JPH045885A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To prevent the generation of a pollution problem, etc., while forming a fine pattern having high accuracy by using a negative type photo-resist for a substrate as a resist coating layer and forming an electrodeposition coating resin layer, etc. CONSTITUTION:A negative type photo-resist is electrodeposited on a substrate 2, in which copper foils in thickness of 35mu as conductive metallic layers 1 are laminated and unified on both surfaces, under conditions of 50mA/dm<2>-three min as a resist coating layer 3, and dried for one min at 80 deg.C. Irradiation and exposure with 200mJ/cm<2> are conducted through the pattern mask of line/space of 50-200mu, and development is performed by using a 1% sodium carbonate solution. An anion group electrodeposition coating resin is electrodeposited through a conventional procedure to shape an electrodeposition resin coated resin layer 4, a 20% lactic acid aqueous solution is spray-coated at 60 deg.C, and the resist coating layer 3 is removed. The layer 1 is etched by a ferric chloride solution at 40 deg.C, and the layer 4 is taken off by using a 3% sodium hydroxide aqueous solution at 40 deg.C, thus acquiring a printed wiring board, from which no pollution problem is generated and to which a fine pattern is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a printed wiring board in which a fine pattern conductive metal layer can be formed at a predetermined position on a substrate.

(Prior art) Conventionally, as a manufacturing method for a printed wiring board on which a fine-pattern conductive metal layer is formed, a dry film is exposed and developed using a mask in a reverse pattern on a substrate coated with a conductive metal layer, and then blown to form a printed wiring board. After removing the exposed portion of the metal layer on which the dry film layer is not formed by etching, the tenting method is used to remove the dry film, followed by solder plating with a dry film layer formed in the same reverse pattern. A solder stripping method is known in which the dry film is removed, the portion where the metal layer is not formed is removed by etching, and then the solder plating is stripped off.

Alternatively, a resist layer with a reverse pattern is formed on a substrate coated with a conductive metal layer, and then plating is performed on the exposed portion of the metal layer that is not covered with the resist layer, and then electrodeposition is performed on the plating layer. A coated resin layer is formed, then the resist layer is removed with an alkaline solution, the metal layer exposed by the removal of the resist layer is removed by etching, and then the electrodeposition coated resin layer is removed. There is also a method of removing it using a highly concentrated alkaline solution or an organic melt.

(Purpose of the Invention) The tenting method and solder peeling method using the above-mentioned dry film lack reliability of adhesion of the dry film to the substrate, making it difficult to form a fine pattern with high precision, and furthermore, the solder has problems with lead pollution. The acid used in the acid treatment process for stripping is a strong inorganic acid such as nitric acid, and the waste liquid contains metals, which poses various problems including waste liquid treatment.

On the other hand, with the method of forming a cyst layer, a fine pattern is formed and problems such as pollution caused by solder do not occur, but the weak alkaline solution used to remove the resist layer is not sufficiently washed with water. If this happens, the adhesion of the electrodeposition coating resin that is subsequently formed will be poor, and a sufficient fine pattern will not be formed.

Therefore, an object of the present invention was invented in view of the problems of the conventional methods as described above, and provides a method for manufacturing a printed wiring board that does not cause pollution problems and can form fine patterns with high precision. It is something to do.

(Means for Achieving the Object) As a result of intensive research, the present inventors have discovered that a certain kind of alkali-removable electrodeposited negative film resist 1- can be removed without using an alkaline solution that affects the next process. We have discovered that this can be done and have come up with the present invention.

That is, the present invention involves forming an alkaline peelable electrodeposited negative photoresist coating layer with a pattern opposite to the desired pattern on a substrate whose entire surface is covered with a conductive metal layer and which has or does not have through holes. Next, an electrodeposited resin layer is formed on the exposed portion of the metal layer where the resist coating layer is not formed, and then the resist coating layer is removed with a weak acid solution, and then the exposed metal layer is removed by etching. death,
This method of manufacturing a printed wiring board is characterized in that the electrodeposited resin layer is then removed using an alkaline solution, an organic solvent, or the like.

The alkaline peelable electrodeposition negative photoresist used here is an acrylic resin-based photocurable resin composition that can be anionically electrodeposited, and is composed of methacrylamide, acrylic acid, and 2-
Benzoin, anthraquinone, 2 - A photopolymerization initiator such as phenylacetophenone is added, and a solvent such as butyl alcohol, diethylene glycol, methyl ethyl ketone, ethyl acetate, etc. is added as necessary.

Next, as the electrodeposition coating resin to be coated on the exposed portion of the conductive metal layer where the resist coating layer is not formed, a resin for ordinary electrodeposition coating can be used, and the resin has carboxylic acid or the like at the end. Anionic electrodeposition coating resins such as liquid polybutadiene resins, styrene-allyl alcohol resins, and acrylic resins are suitable, and are formed by known methods.

Next, the weak acid used to remove the resist coating layer is an organic acid such as lactic acid, hydroxyacetic acid, or trichloroacetic acid, and among these, lactic acid is preferably used because it facilitates the removal of the resist coating layer.

(Example) A negative photoresist (Kansai Paint HH Sonne EDU) was applied as a resist coating layer (3) to a substrate (2) on which a 35μ thick copper foil was laminated and integrally fixed on both sides as a conductive metal layer (1).
Electrodeposit V376) at 50 mA/d baud for 3 minutes at 80°C.
After drying for 1 minute, it was exposed to 200 mJ/cm2 through a pattern mask with lines/spaces of 50 to 200 microns, and then developed using a 1% sodium carbonate solution. Next, anionic electrodeposition coating resin (Aron S-40 manufactured by Toagosei ■)
90 as a main component) was electrodeposited by a conventional method to form an electrodeposition resin coating resin layer (4), and heated at 60°C-20.
% lactic acid aqueous solution was spray applied to the resist coating layer (
3) was removed.

Subsequently, the exposed conductive metal layer (1) is etched with a 40°C ferric chloride solution, and then the electrodeposited resin layer is etched with a 3% I-lium hydroxide aqueous solution at 40°C. (
4) was removed to obtain a printed wiring board (5) on which a fine pattern of 70 μm lines/spaces was formed.

(Effects) According to the present invention, since there is no need to use a dry film or solder, fine patterns with higher precision can be formed, and strong acids such as nitric acid can be used to remove lead and solder contained in the solder. No pollution problems will occur.

Also, unlike the conventional alkali-alkali removal method, since the resist coating layer is removed with acid, the alkali used to remove the conventional resist coating layer affects the electrodeposition of the next electrodeposition coating resin. The electrodeposited resin has excellent adhesion and process control is easy.

[Brief explanation of drawings]

The figure shows the manufacturing process of the printed wiring board of the present invention.
Figure 1 shows a state in which a resist layer with a reverse pattern is formed on a substrate on which a conductive metal layer is formed, Figure 2 shows a state in which an electrodeposition coating resin layer is formed, and Figure 3 shows a state in which the resist layer is coated with lactic acid. FIG. 4 is a sectional view showing the finished state of the printed wiring board according to the present invention after the electrocoated resin layer has been removed and the exposed portion of the conductive aluminum carbon layer has been etched. 1: Conductive metal M 2: Substrate 3 Ni-resist coated M layer 4: Electrodeposition coating resin layer 5 Ni-blint wiring board Patent applicant Aikani Gyo Co., Ltd.

Claims (1)

[Claims] On a substrate with or without through holes whose entire surface is covered with a conductive metal layer, an alkaline peelable electrodeposited negative photoresist coating layer with a pattern opposite to the pattern to be obtained is formed, and then the resist coating layer is formed. Forming an electrodeposition coating resin layer on the exposed portion of the metal layer where is not formed,
Printed wiring characterized in that the resist coating layer is then removed with a weak acid solution, the exposed metal layer is removed by etching, and then the electrodeposited resin layer is removed with an alkaline solution, an organic solvent, etc. Method of manufacturing the board.