JPH0487392A - Manufacture of wiring board - Google Patents

Abstract

PURPOSE:To enhance the precision property and stability of a resist layer and to make possible the formation of circuits, which are high in accuracy and density, by a method wherein an exposure and development type second resist is applied on the whole surface of a board and this second resist is exposed and developed according to wiring patterns. CONSTITUTION:Wiring patterns 2 are formed on a board 1 and thereafter, the peripheries of connecting terminal parts 2a are reliably removed in consideration of printing accuracy, thermosetting ink for resist use is partially applied by a technique, such as a screen printing technique or the like, is thermoset and a weatherable, chemical- resistant, insulative and solder-resistant first resist film 3 is formed on wiring circuits 2b on the board 1, on which the wiring patterns exist in a high density. An exposure and developing type resist is applied and semicured on the whole surface of the board 1. An exposure is performed via a mask and thereafter, the mask is removed and the resist is developed. The resist on the parts 2a is removed, the resist other than the removed resist is completely curd by a posture process and a second resist layer 4 is formed. Accordingly, the wiring circuits 2b can be protected from contamination, disconnection and the like by the wiring board and it becomes possible that components are respectively soldered reliably on the parts 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a wiring board in which a fine resist pattern can be precisely formed.

[Summary of the invention]

In the present invention, a resist layer is partially formed using a thermosetting first resist on a substrate on which a wiring pattern is formed, and then a resist layer corresponding to the wiring pattern is formed using an exposure and development type second resist. This enables the formation of a precise and highly stable resist layer, increasing the density of wiring circuits.

The present invention aims to provide a method for manufacturing a wiring board that can improve precision.

(Prior Art) In a wiring board, a resist layer formed on a board on which a wiring circuit is formed is used to prevent solder from adhering to unnecessary parts when soldering components to printed wiring using the dip method. This resist layer has solder resistance as well as the effect of protecting wiring circuits from disconnection and contamination, and is essential for forming wiring boards with high reliability.

Recently, in wiring boards, the density of wiring circuits has become higher and higher.
As precision increases, finer patterns are also required for such resist layers.

For this reason, a resist layer with a fine pattern can be precisely formed, and the resist layer can be stably maintained on the wiring circuit even if the formed resist layer is exposed to a plating solution or placed in a high humidity environment. It has become necessary to develop a method for forming wiring boards in order to maintain reliability and high precision of wiring boards.

By the way, as a method to form such a resist layer on a substrate so far, a screen printing method has been adopted in which a thermosetting resist is printed on the substrate using a menonue-shaped screen with sol formed on the masking part. It's here.

The thermosetting resist used in this screen printing method is chemically stable, so this method provides weather resistance,
A resist layer with excellent chemical resistance and insulation properties can be formed.

However, when attempting to form fine patterns using this screen printing method, the screen is distorted when the resist ink is pushed out from the screen with a roller, making it difficult to align the wiring circuit and the resist, or the resist layer is distorted. Sometimes they were not formed accurately on the wiring circuit. Further, the resist wraps around the lower part of the masking sol formed on the screen, causing problems such as the resist layer bleeding. Therefore, this method cannot form a resist layer with a fine pattern, and cannot be used to manufacture a high-density wiring board.

Therefore, as a method for forming a resist layer other than screen printing, the photo-method using a photosensitive resist has recently been adopted.

This method is a method in which a photosensitive resist is applied to the entire surface of a substrate by a screen method, a roller coating method, a spray method, or a curtain coater method, and only the portion where the resist layer is to be formed is selectively exposed to light and photocured.

Since this method does not use a screen or roller for pattern formation, the resist layer does not shift or bleed, and it is possible to form a finer resist pattern than the above-mentioned screen printing method.

However, the photosensitive resist used in this method has a highly reactive structure that is partially cured by ultraviolet rays, and is chemically unstable.

Therefore, the resist layer formed by this method is poor in weather resistance, chemical resistance, insulation, etc., and has a wide spread that causes problems if, for example, plating is attempted after the resist layer is formed.

[Problems to be Solved by the Invention] As described above, when attempting to form a resist layer using conventional techniques, fine patterns may not be formed accurately, or fine patterns may be formed but the stability of the resist layer may not be stable. There are many problems such as insufficient wiring, high density wiring circuits,
There is a limit to high precision.

Therefore, the present invention was proposed in view of such conventional circumstances, and it is important to improve the precision of the resist layer.

It is an object of the present invention to provide a method for manufacturing a wiring board that enables circuit formation with high accuracy and density by increasing stability.

In order to achieve the above-mentioned object, the method for manufacturing a wiring board of the present invention includes forming a wiring pattern on a substrate, and forming a thermosetting first
After partially applying the resist, a second resist of an exposure and development type is applied to the entire surface, and the second resist is exposed and developed in accordance with the wiring pattern.

[Effect]

In the method for manufacturing a wiring board of the present invention, the thermosetting first resist is partially applied onto the substrate on which the wiring pattern is formed, so that the weather-resistant chemical resistance.

A solder-resistant resist layer with insulation properties is formed 6
In addition, after applying the first resist, a second resist of exposure and development type is applied.
A resist is applied to the entire surface of the substrate, and this second resist is exposed and developed in accordance with the wiring pattern, so that a solder-resistant resist layer is precisely formed on the entire surface of the substrate in accordance with the wiring pattern.

[Means to solve the problem]

[Example] Hereinafter, specific examples of the present invention will be described with reference to the drawings.

First, to manufacture a wiring board, copper foil is laminated onto an insulating board (1). Then, an etching resist is formed on the copper foil according to a desired wiring pattern, and etching is performed as shown in FIGS. 1A and 1B.
A wiring pattern (2) consisting of a predetermined connection terminal portion (2a) and a wiring circuit (2b) is formed. At this time, the etching resist may be patterned by ordinary photolithography, and the copper foil may be etched by any method such as wet etching or dry etching.

After the wiring pattern (2) is thus formed on the substrate (1), a resist layer is further formed on the substrate (1).

When forming the resist layer, as shown in FIGS. 2A and 2B, first, the connection terminal portion (2a
) A thermosetting resist ink that will become the first resist is partially applied to the surface of the substrate (1) by a method such as screen printing to the extent that the periphery can be reliably removed, and this is thermoset to form the first resist. A resist layer (3) is formed. That is, Figure 2B
As shown in , a first resist layer is formed on a wiring circuit (2b) in which wiring patterns are present at high density. The thermosetting resist ink used here may be any ink that is normally used as a thermosetting resist ink, such as epoxy resin.
It is not particularly limited.

Next, an exposure and development type resist serving as a second resist is applied to the entire surface of the substrate (1) and semi-cured.

Next, after exposure through a mask, the mask is removed and the resist is developed. Then, as shown in FIGS. 3A and 3B, the resist on the connection terminal portion (2a) is removed and completely cured by a post-cure process to form a second resist layer (4). That is, as shown in FIG. 3B, a second resist layer is further formed on the first resist layer over the entire surface of the substrate except for the connection terminal portions. Note that here, the exposure and development type resist may be either a positive type or a negative type. In this example, a negative type resist that is cured by ultraviolet irradiation was used.

In the wiring board manufactured in this way, the portion excluding the area around the connection terminal portion (2a), that is, the wiring circuit (2b)
A solder-resistant first resist layer (3) having weather resistance, chemical resistance, and insulation properties was formed in the area where . In addition, there is a wiring pattern (2) on the entire surface of the board (1).
Accordingly, a solder-resistant second resist layer (4) was formed with precisely shaped openings (4a). Therefore, the wiring board manufactured in this way has a wiring circuit (2b)
It has been shown that it is possible to protect the terminal from contamination, disconnection, etc., and it is also possible to reliably solder components to the connection terminal portion (2a).

Furthermore, in the manufacturing method according to the present invention, if it is necessary to plate the connection terminal portion (2a), the plating treatment can be performed after forming the first resist layer (3). The plating process before forming the resist layer is performed on the wiring pattern (
2), there is a high possibility that the plating will be deposited in the lateral direction, and that the insulation between the wirings will deteriorate in the area where the wiring circuits (2b) are formed in high density. Therefore, if the plating treatment is performed after the formation of this first resist layer, the first resist layer (3) has excellent chemical resistance, weather resistance, and insulation properties as described above, so that the accuracy of the wiring circuit will not be reduced. It is possible to apply plating without any need for plating.

[Effects of the Invention] As is clear from the above explanation, in the method for manufacturing a wiring board of the present invention, the thermosetting first resist is partially applied on the board on which the wiring pattern is formed. ,
Most of the substrate is protected by a solder-resistant resist layer that has chemical resistance and plating resistance. In addition, after applying the first resist, a second resist of an exposure and development type is applied to the entire surface, and this second resist is exposed and developed according to the wiring pattern, so that the resistor has a precise opening shape. A solderable resist layer is formed according to the wiring pattern.

Therefore, according to the present invention, it is possible to manufacture a wiring board with high reliability and high precision.

[Brief explanation of the drawing]

1 to 3 show an embodiment to which the present invention is applied in the order of steps, FIG. 1A is a schematic plan view of the main part showing the process of forming a wiring pattern, and FIG. 1B is a diagram of FIG. FIG. 2A is a schematic plan view of the main part showing the first resist layer forming step, and FIG. 2B is a main part taken along the A-A line of FIG. 2A. A schematic cross-sectional view, FIG. 3A is a schematic plan view of a main part showing the process of forming the second resist layer, and FIG. 3B is a schematic cross-sectional view of a main part along A-Awa in FIG. 3A. 2... Wiring pattern 3... First resist layer 4... Second resist layer

Claims (1)

[Claims] After forming a wiring pattern on a substrate and partially applying a first thermosetting resist, a second resist of an exposure and development type is applied to the entire surface, and a wiring pattern is formed according to the wiring pattern. A method for manufacturing a wiring board, comprising exposing and developing a second resist of the lever.