JPH05259609A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To make it possible to increase the wiring density and perform a folding using flexibility by selectively precipitating a metal resist layer using a plating layer on a protrusion region and a masking technique after selectively removing a plating layer on a recess region and performing a wiring pattern using the metal resist layer as a mask. CONSTITUTION:A recess region 2d formed by a stepping, a protrusion region 2e and a through hole 2c' are covered and formed on the main face, and a chemical copper plating layer 3a and an electrical copper plating layer 3b are covered and formed on the inner wall face. Then, a dry film etching resist layer is placed on the protrusion region 2e. After the recess region 2d and a plating layer 3 formed in its circumference are removed by an etching, a dry film plating resist layer 6 is placed on the surface of a printed wiring board and a plating resist patterning is performed by a selective exposure and a developing treatment. Then, an electrical copper plating layer 3b' and a solder layer 8 are covered and formed on the plating layer 3. After a plating resist pattern 6a is stript and removed. the plating layers 3a, 3b and 3b' are selectively removed by the etching.

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, and more particularly to a method for manufacturing a printed wiring board which is composed of a hard printed wiring unit portion and a flexible portion and which can be bent and used.

[0002]

2. Description of the Related Art Conventionally, the following structure has been adopted as a circuit structure which also serves as a wiring connection portion and a device casing which are required to have flexibility, or as a wiring or circuit unit which is laminated and compacted. A foldable printed wiring board is known. That is, there is known a printed wiring board in which a hard printed wiring board unit is appropriately laminated on a flexible board surface so as to be laminated and integrated, and a flexible wiring board forming the separated portion can be bent and used. FIG. 4 is a cross-sectional view showing the structure of the main part of such a bendable printed wiring board. 1 is a flexible substrate part, and 2 and 2'are connected and integrated by the flexible substrate part 1. Rigid printed wiring board part, 2a, 2b
Is a wiring pattern provided on the hard printed wiring boards 2 and 2 ', and 2c is a through hole connecting portion for connecting predetermined wiring patterns of the hard printed wiring boards 2 and 2'. Then, in the printed wiring board having this configuration, the flexibility of the flexible substrate portion 1 enables bending. Moreover, it is also possible to use the recessed portion forming the flexible substrate portion 1 as a mounting / mounting area for electronic components.

A printed wiring board of this type is generally manufactured as follows. First, Fig. 5 (a)-
As shown schematically in (c), an embodiment of the adhesive layer (such as an epoxy resin) on a predetermined area surface of the flexible substrate 1 having a thickness of about mm and having a required inner layer wiring pattern, for example. A sheet or coating layer is arranged in advance, and a hard printed wiring board 2, 2'having a thickness of about 0.1 to 0.3 mm and a required inner layer wiring pattern is positioned and arranged on this adhesive layer surface. After stacking, pressure and heat are integrated. In this way, a printed wiring board having a concave surface region 2d and a convex surface region 2e whose main surface is stepped is obtained, and after a required connecting through hole 2c 'is drilled in the printed wiring board, the exposed concave surface region 2d and convex surface region 2e are formed. Further, the chemical copper plating layer 3a and the electrolytic copper plating layer 3b are sequentially deposited and formed on the inner wall surface of the through hole 2c '(FIG. 5 (a)). Next, after forming a required etching resist pattern 4 using a photosensitive dry film on both main surfaces of the printed wiring board on which the plating layer 3 is deposited / formed (FIG. 5 (b)), an etching treatment is performed. Then, the plating layer 3 is selectively etched and removed to form a required wiring pattern, and then the etching resist pattern 4 is peeled and removed to obtain a printed wiring board having a stepped main surface. (Fig. 5 (c)).

[0004]

However, since the manufacturing method of the printed wiring board is basically the formation of the wiring pattern by the tenting method, the wiring pattern width is 1
It is not suitable for forming fine wiring patterns of about 50 μm or less. That is, it is unsuitable for manufacturing a printed wiring board having a structure in which the wiring pattern is miniaturized to increase the wiring density, and it is necessary to protect the plating layer 3 of the through-hole connecting portion 2c. Therefore, the etching resist film (pattern Since the area occupied by 4) is set to be relatively large, the land area of the through-hole connecting portion 2c must be relatively large, which also impedes the improvement of the wiring density.

In response to these problems, when the wiring pattern is formed by using a so-called metal resist method, the following problems are recognized. For example, in order to selectively deposit the metal resist on the convex surface area 2e where the main surface is stepped (the metal resist is not deposited on the concave surface area 2d), it is necessary to tenting the dry film. However, the tented dry film tends to hang down in the concave region 2d as schematically shown in FIG. Moreover, the dry film 5
Has a relatively low mechanical strength, so that damage is likely to occur in the post-exposure development process in which selective masking is performed, and therefore, precipitation of the metal resist in the concave region 2d may not be prevented.

The present invention has been made to solve the above problems, and the main surface has a concave surface area and a convex surface area due to step formation without requiring complicated steps or special equipment, and at least a convex surface. An object of the present invention is to provide a manufacturing method capable of easily manufacturing a printed wiring board in which a required circuit pattern is provided in a region and which can be bent.

[0007]

According to a method of manufacturing a printed wiring board according to the present invention, a main surface has a concave region and a convex region by step formation, and a required wiring pattern is provided at least in the convex region. A method of manufacturing a wiring board, comprising the steps of depositing / forming a plating layer connected to the concave area and the convex area, and selectively etching at least the plating layer in the concave area of the deposited / formed plating layer. It is characterized by comprising a step of removing and a step of forming a required wiring pattern of the plating layer in the convex area by a metal resist method.

In the above manufacturing method, when the through-hole connection portion is formed after the first plating layer is formed, it is preferable to perform desmear treatment on the through-hole inner wall surface that has been drilled before the through-hole inner wall surface is plated. .. Further, in the screen printing of the solder resist layer in the final manufacturing stage, it is desirable to dispose a spacer capable of forming a flat surface with a convex area in a portion corresponding to the concave area in the screen plate used. ..

[0009]

According to the method of manufacturing a printed wiring board of the present invention, the plating layer in the concave area due to the step formation is selectively removed by the so-called tenting method, and then the plating layer in the convex area and the masking technique are used. Since the metal resist layer is selectively deposited, deposition of the metal resist layer on the concave region is completely eliminated. Since the wiring pattern is formed using the metal resist as a mask, it functions as a finely-wiring printed wiring board (high wiring density) and can be bent using the flexibility of the concave area. A printed wiring board can be obtained.

[0010]

Embodiments of the present invention will be described below with reference to FIGS.

1 to 3 schematically show an embodiment of a method for manufacturing a printed wiring board according to the present invention. First,
For example, an adhesive layer (sheet or coating layer) of epoxy resin or the like is previously arranged on a predetermined area surface of the flexible substrate 1 having a thickness of about mm and provided with a required inner layer wiring pattern, and this adhesion is performed. Thickness of 0.1 on the agent layer surface
After positioning, arranging and stacking the hard printed wiring boards 2 and 2'having a required inner layer wiring pattern and having a thickness of about 0.3 mm, pressure and heating are integrated. In this way, a printed wiring board having a concave surface region 2d and a convex surface region 2e whose main surface is stepped is obtained, and after a required connecting through hole 2c 'is drilled in the printed wiring board, the exposed concave surface region 2d and convex surface region 2e are formed. Then, a chemical copper plating layer 3a with a thickness of approximately 10 μm and an electrolytic copper plating layer 3b with a thickness of approximately 10 μm are sequentially deposited and formed on the inner wall surface of the through hole 2c ′, and then a dry film etching resist layer 5 is formed on the convex area 2e. (Fig. 1).

Next, using the dry film etching resist layer 5 arranged as a mask, the exposed plating layers (chemical copper plating layer 3a and electrolytic copper plating layer 3b) 3,
In other words, the concave region 2d and the plating layer 3 on the periphery thereof are removed by etching. After that, the dry film plating resist layer 6 is arranged on the surface of the printed wiring board including the concave area 2d and the convex area 2e, and the artwork film 7 is formed.
So-called selective exposure was carried out (FIG. 2), and further development processing was performed to perform plating resist patterning. Plating resist pattern 6a by the above plating resist patterning
The printed wiring board formed with is subjected to the second electroplating treatment, and the electroplated copper layer 3b 'and the solder layer 8 serving as a metal etching resist are sequentially deposited on the exposed plating layer 3. Formed (FIG. 3). After that, the plating resist pattern 6a was removed and removed, and then the exposed plating layer 3 was selectively removed by etching using the solder layer 8 as a metal etching resist.

In this way, a printed wiring board was obtained in which the main surface had a concave surface area and a convex surface area due to step formation, and at least the required wiring pattern was provided in the convex surface area. In this printed wiring board, a fine wiring pattern can be formed in the convex area and can be bent due to the flexibility of the concave area. By bending and laminating, a compact circuit structure can be formed.

In the above series of steps, required plating layers (chemical copper plating layer 3a and electrolytic copper plating layer 3b) 3
After forming the connecting through hole 2c ′, the inner wall surface of the connecting through hole 2c ′ is treated with a permanganate solution to remove the desmear, and then the inner wall surface of the connecting through hole 2c ′ is treated with chemical copper. It was confirmed that when the plating layer was formed, damage to the surface layer (cover film) of the flexible substrate 1 having the inner layer wiring pattern could be easily prevented.

Further, a so-called solder resist layer is screen-printed on the surface of the printed wiring board having the concave surface and the convex surface area by the step formation, the main surface manufactured by the above, and having a required wiring pattern in at least the convex surface area. When depositing and forming with, the corresponding area spacer of the screen plate is arranged so that the screen plate can be arranged in the area facing the concave area of the printed wiring board by filling the concave area and forming a plane with the convex area. Then, the solder resist layer was deposited and formed by the screen printing method. In this way, when the appearance of the printed wiring board on which the solder resist layer was deposited / formed was observed in detail, the solder resist layer of the required thickness was uniformly deposited / formed in the required area. No risk of short-circuiting between wiring patterns was observed when mounting or electronic components.

[0016]

As described above, according to the method for manufacturing a printed wiring board of the present invention, the main surface has the concave surface area and the convex surface area by the step formation, and the fine wiring pattern is provided at least in the convex surface area. A printed wiring board can be easily manufactured with a high yield. That is, since the metal resist method is adopted, a wiring pattern can be formed finely, and since Setsuzokland can be installed in a relatively small area, a printed wiring board having a high wiring density as a whole can be easily manufactured. .. Then, by applying desmear treatment to the inner wall surface of the connecting through-hole, or considering the configuration of the screen plate used for screen printing of the solder resist layer as described above, it is possible to improve the reliability of the printed wiring board functionally. It becomes possible to manufacture.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a state in which an etching resist layer is arranged in a method for manufacturing a printed wiring board according to the present invention.

FIG. 2 is a sectional view schematically showing a state in which a plating resist pattern is formed in the method for manufacturing a printed wiring board according to the present invention.

FIG. 3 is a sectional view schematically showing a state in which a solder plating layer is selectively formed in the method for manufacturing a printed wiring board according to the present invention. Sectional drawing of the printed wiring board manufactured by the manufacturing method of the printed wiring board which concerns on this invention.

FIG. 4 is a cross-sectional view showing a configuration example of a main part of a conventional printed wiring board.

FIG. 5 schematically shows an embodiment of a conventional method for producing a printed wiring board, (a) is a sectional view showing a state in which a plating layer is formed, and (b) is a state in which an etching pattern is formed. Sectional drawing shown, (c) is a sectional view showing a state in which a wiring pattern is formed.

FIG. 6 is a cross-sectional view schematically showing a state in which a dry film is tented in forming a wiring pattern by a metal resist method in a conventional printed wiring board manufacturing method.

[Explanation of symbols]

 1 ... Flexible substrate 2, 2 '... Hard printed wiring board 2a, 2b ... Wiring pattern 2c ... Through hole connection 2c' ... Through hole 2d ... Concave area 2e of hard printed wiring board ... Hard printed wiring board Convex area 3a ... Chemical copper plating layers 3b, 3b '... Electrolytic copper plating layer 4 ... Etching resist pattern 5 ... Dry film etching resist 6 ... Dry film plating resist 6a ... Plating resist pattern 7 ... Artwork film 8 ... Solder layer

Claims (1)

[Claims] 1. A method for manufacturing a printed wiring board, the main surface of which has a concave region and a convex region by step formation, and a required wiring pattern is provided in at least the convex region, wherein the concave region and the convex region are provided. A step of depositing / forming a continuous plating layer; a step of selectively etching and removing at least the concave plating area of the depositing / formed plating layer; and a step of metal resisting the convex area plating layer. A method of manufacturing a printed wiring board, comprising the step of forming a required wiring pattern.