JPS61216386A - Manufacture of flexible printed wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing printed wiring boards, particularly flexible printed wiring boards.

[Background Art] In recent years, electronic devices have made remarkable progress, and these devices are also rapidly becoming smaller and thinner.

In response to the miniaturization and thinning of electronic devices, flexible printed wiring boards are attracting attention because they are flexible and have a high degree of freedom in designing electronic devices that are becoming smaller and more dense.

Conventionally, as a typical method for manufacturing such a flexible printed wiring board, a method is known in which a conductor circuit of the flexible printed wiring board is formed using chemical etching.

In a method of manufacturing a flexible printed wiring board using such a chemical etching method, for example, as shown in FIG. 4, an insulating base material I and a conductor [
After laminating the conductor layer 2, as shown in FIG.
A mask layer 3 made of photoresist or the like is formed in a pattern on the top, and the conductor layer 2 not covered with the L mask layer 3 is chemically kneaded with an etching solution to form a 6th layer.
A common method has been to form a conductor circuit having a desired circuit pattern as shown in the figure.

However, in a flexible printed wiring board with a laminated structure created by laminating a conductor layer on an insulating layer such as the above-mentioned insulating base material, the insulating layer and the conductor layer may peel off due to heating or bending, or the conductor layer may peel off due to heating or bending. Depending on the ductility of the layers, problems such as wire breakage occurred. Furthermore, in flexible printed wiring boards, an expensive polyimide film is generally used as an insulating base material due to heat resistance, etc., and it has been difficult to reduce the price.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points, and the main purpose of the present invention is to solve problems such as peeling and disconnection in conventional flexible printed wiring boards with a laminated structure. It is an object of the present invention to provide a new method for manufacturing a flexible printed wiring board that eliminates the above problems.

Another object of the present invention is to provide a novel method for manufacturing a flexible printed wiring board that can produce an inexpensive flexible printed wiring board.

[Means for Solving the Problems] The above objects of the present invention are achieved by the present invention below.

1) Forming a mask layer on the conductive base material according to the circuit formation pattern to prevent the material from becoming insulated; 2) Insulating the part of the base material other than the part on which the mask layer is formed. hand,
A method for manufacturing a flexible printed wiring board, comprising the step of leaving a mask layer forming portion of the base material as a conductive circuit.

[Embodiment J of the invention In the method of the present invention, methods for insulating the conductive substrate include, for example, an aqueous solution of sulfuric acid, oxalic acid, chromic acid, etc., a mixed solution thereof, or a non-aqueous solution such as dimethylformamide. Methods of insulating the base material by oxidizing it can be widely applied, such as anodic oxidation in liquid, oxidation with chemicals such as chromate coating acid bath, or heating oxidation in the presence of oxygen. Although not limited to,
Anodic oxidation is preferably used.

When insulating the above-mentioned base material, in order to prevent the base material in the area where the conductor circuit is to be formed from becoming insulated, a mask layer of ψ is placed in advance on the surface of the base material in the area where the conductor circuit is to be formed in accordance with the circuit formation pattern. provided. As a method for forming the mask layer, a method using a dry film, a negative type or positive type photoresist, etc. is applied. Due to the insulation prevention effect of this mask layer, the conductivity of the surface layer of the base material covered with the mask is maintained, and the parts other than the surface layer of the base material covered with the mask are insulated, and the surface layer of the base material is insulated. A conductor circuit with a desired pattern is formed in the portion. of course,
The mask layer is removed after the conductor circuit is formed.

In a conductor circuit formed by insulating such a conductive base material, the insulating layer and the conductor circuit are integrated, and peeling or disconnection does not occur.

Hereinafter, the present invention will be described in further detail with reference to the drawings.

FIGS. 1 to 3 are schematic diagrams for explaining the basic aspects of the present invention, and each of FIGS.
An example of the structure of a flexible printed wiring board and its manufacturing procedure according to the method of the present invention is shown.

First, in one embodiment, a conductive base material 4 as shown in Figure W41 is used, for example. As the base material, for example, A1. Examples include metals such as Cu, Ni, and Sn, and alloys thereof, and among them, aluminum alloys such as duralumin are preferably used. These base materials can be used in any desired shape, such as a sheet or film, but
To maintain good flexibility, the base material thickness should be 1ON40.
- It is preferable to set it as about.

Next, a photoresist 5 for forming a mask layer is laminated on the conductive base material 4 so as to cover at least the surface of the base material where the conductor circuit is to be formed (in this example, one entire surface of the base material 4). Ru. Of course, as mentioned above, there are means for forming the mask layer.

The material is not limited to photoresist, and although a negative photoresist is used in this example, a positive photoresist may also be used.

To laminate the photoresist 5 on the base material 4), for example, if it is a liquid resist, use a coating means such as a spinner, or if a film resist is used, use a laminator or the like to laminate the photoresist 5 on the base material 4. Adhere and solidify. The material of the photoresist is not particularly limited, and various commercially available materials can be used. It is preferable to select and use it appropriately depending on the material of the base material and the like.

Next, the E photoresist 5 is exposed to ultraviolet rays, far ultraviolet rays, X-rays, electron beams, etc. through an exposure mask with a desired pattern corresponding to the circuit pattern to be formed, and then the unexposed portions of the resist are removed. A mask layer 6 as shown in FIG. 2 is formed in a desired pattern on the conductive base material 4 by dissolving the photoresist with a special developer depending on the type of photoresist.
get.

Next, on the conductive base material 4 on which the mask layer 6 was formed,
By performing an insulating process using the above-mentioned anodic oxidation method, the insulating layer 7 and the conductor circuit 8 are integrated as shown in FIG. 3, and the conductor circuit 8 is formed in a desired pattern.A flexible printed wiring is obtained. Get a board. Treatment conditions used when performing the above insulation treatment (for example, in the case of anodic oxidation).

The type, concentration, current density, etc. of the electrolytic solution can be determined depending on the material of the base material, etc.

Finally, the mask layer 6 on the conductor circuit 8 is dissolved and removed using a special solution depending on the type of photoresist to complete the flexible printed wiring board.

The flexible printed wiring board formed by the method described above has a single-layer structure in which the conductor circuit and the insulating layer are integrated, and is not prone to peeling or disconnection as in conventional flexible printed wiring boards with a laminated structure. No problems such as this will occur.

Furthermore, since there is no need to use an expensive polyimide film, it is also possible to provide an inexpensive flexible printed wiring board.

[Example] EXAMPLES The present invention will be explained in more detail by showing examples below.

[Example 1] A flexible printed wiring board of this example was produced using a 30-thick duralumin thin plate as a conductive base material according to the manufacturing procedure shown in Figs. W41 to Fig. 3.

First, an organic solvent-soluble negative liquid resist (trade name: OMR-1113,
(manufactured by Tokyo Ohka Co., Ltd.) was applied by dip coating to a thickness of about 5 μm and allowed to adhere and harden.

Next, after exposing the resist to light through a predetermined exposure mask, the unexposed portions of the resist were exposed to 0NR-83.
It was dissolved and removed using a special developer to form a patterned mask layer on the duralumin thin plate.

Next, the duralumin thin plate on which the mask layer was formed was immersed as a positive electrode in an anodizing bath containing 180 g/It of sulfuric acid and 5% glycerin at a bath temperature of 30° C. and a current density of 1.
5A/dffl" for about 30 minutes. After thoroughly washing the duralumin thin plate after I! with water, the mask layer was dissolved in solution@502 (trade name, manufactured by Tokyo Ohka Co., Ltd.). ) to obtain a flexible printed wiring board.

A conductor circuit with a desired pattern was formed on the wiring board, and no problems such as peeling or disconnection occurred.

[Effects of the Invention] As explained above, in the present invention, a conductive circuit is formed by insulating the portion of the conductive base material other than the portion where the conductive circuit is formed. It is now possible to create a flexible printed wiring board with a layered structure, and to provide a new method for manufacturing a flexible printed wiring board that eliminates problems such as peeling and disconnection in conventional flexible printed wiring boards with a laminated structure. Ta. Furthermore, since there is no need to use an expensive polyimide film, it has become possible to provide an inexpensive flexible printed wiring board.

[Brief explanation of drawings]

1 to 3rgJ are schematic diagrams for explaining basic aspects of the method for manufacturing a flexible printed wiring board of the present invention, and FIGS. 4 to 6 are conventional methods for manufacturing a flexible printed wiring board. FIG. 2 is a schematic diagram for explaining a typical aspect. 1--Insulating base material 2-m-Conductor layer 3.8--
Mask layer 4-m-conductive base material 5--photoresist

Claims (1)

[Claims] (1) 1) Forming a mask layer on a conductive base material according to a circuit formation pattern to prevent the base material from being insulated; and 2) Insulating the base material other than the mask layer formation portion. Process it and
A method for manufacturing a flexible printed wiring board, comprising the step of leaving a mask layer forming portion of the base material as a conductive circuit.