JPH0537140A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE:To improve yield and producibility in a solder resist and load map formation process and to provide a printed wiring board of good position accuracy and shape reproducibility in a manufacturing method of a printed wiring board used for various electronic devices. CONSTITUTION:A first photosensitive layer is formed of photosensitive ink 13 of high sensitivity on a printed wiring board wherein a conductor pattern 12 is formed. Photosensitive ink 14 having the same basis as the first layer, different tone therefrom and low sensitivity is applied to and dried on the first photosensitive layer to form a second photosensitive layer. Thereafter, the first and second photosensitive layers are exposed and developed by a mask film 15 with photographic density difference, and a solder resist 16 and a load map 17 are formed at the same time. Thereby, it is possible to omit a process and to acquire a printed wiring board having higher accuracy of shape and position relation between the solder resist 16 and the load map 17.

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 used in various electronic devices such as personal computers and word processors.

[0002]

2. Description of the Related Art In recent years, printed wiring boards, which are widely used in various electronic devices, have been remarkably increased in wiring density and surface mounted electronic components due to downsizing, weight reduction and multifunction of electronic devices. Conductor patterns formed on insulating boards and lands on which electronic components are mounted are becoming increasingly narrower in pitch, thinner and smaller in size, preventing solder from adhering to unnecessary parts, protecting conductor patterns against oxidation, and maintaining insulation. High resolution and high positional accuracy are required for the solder resist and roadmap formed on the printed wiring board for the purpose of improving the solderability and solderability. It is replacing the law.

A conventional printed wiring board will be described below. FIG. 3 shows a manufacturing process of forming a solder resist and a roadmap by a conventional photo-developing method for a printed wiring board.

In FIG. 3, 1 is an insulating substrate, 2 is a conductor pattern, 3a is a photosensitive solder resist ink, 3b is a solder resist, 4 is a solder resist forming mask film, 5a is a photosensitive roadmap ink, and 5b is a road. A map 6 is a mask film for forming a road map.

The formation of the solder resist and the road map of the printed wiring board constructed as described above will be described below.

First, an etching resist is formed on a copper clad laminate (not shown) cut into a predetermined size by a screen printing method or a photo developing method, and then a solution of cupric chloride or the like is used. The conductor pattern 2 is formed by etching, and the etching resist is peeled off.

As shown in FIG. 3A, a photosensitive solder resist ink 3a is applied to a printed wiring board having a conductor pattern 2 formed on an insulating substrate 1 and dried by touching with hot air.

Next, as shown in FIG. 3B, the solder resist forming mask film 4 is brought into close contact with the surface of the photosensitive solder resist ink 3a which has been touch-dried, and is exposed to ultraviolet rays. As described above, the unexposed portion is developed and removed with a predetermined developing solution to form the solder resist 3b. After that, as shown in FIG. 3 (d), the photosensitive roadmap ink 5a is applied on the solder resist 3b in an area slightly larger than the area required for forming the roadmap 5b, and similarly touch-drying is performed. As shown in (e), the mask film 6 for forming a roadmap is brought into close contact with the surface of the photosensitive roadmap ink 5a that has been dried by touching with the finger and exposed to ultraviolet rays. Then, as shown in FIG. Develop and remove with the developer.

After that, in order to improve the adhesion and hardness to the insulating substrate and the conductor pattern, it is treated again with hot air,
The solder resist 3b and the road map 5b are formed on the printed wiring board.

[0010]

However, in the above conventional structure, although the solder resist 3b and the road map 5b formed on the printed wiring board have high resolution, the application of the photosensitive solder resist ink 3a, Touch-dry, alignment of mask film 4 for solder resist formation, exposure, development, and photosensitive roadmap ink 5
The mass production is poor because the manufacturing process such as the coating of a, the touch drying, the alignment of the mask film 6 for forming the roadmap, the exposure and the development is complicated and takes a long time, and the solder resist 3 is used.
It is difficult to maintain the relative positional accuracy of the formed solder resist 3b and the road map 5b because the steps of forming b and the road map 5b are different.

Further, the photosensitive roadmap ink 5 is formed on the solder resist 3b having an uneven surface after development and formation.
In order to apply a, the photosensitive roadmap ink 5a applied, the surface of the solder resist 3b, the surface of the insulating substrate 1 and the surface of the conductor pattern 2 become uneven. For this reason, a sufficient contact state with the roadmap forming mask film 6 at the time of exposure cannot be maintained, which causes a diffraction phenomenon of ultraviolet rays in the mask film shielding portion, and the shape of the roadmap 5b after development and formation is in a designed state. There was a problem that the shape of the mask film was not reproduced, and in a remarkable case, characters and symbols could not be read, and the production yield of the printed wiring board in the roadmap forming process was deteriorated.

The present invention solves the above-mentioned problems of the prior art by remarkably improving the manufacturing yield and productivity of printed wiring boards in the process of forming a solder resist and a roadmap using a photosensitive solder resist ink and a photosensitive roadmap ink. An object of the present invention is to provide a printed wiring board having excellent relative positional accuracy between a solder resist and a road map and shape reproducibility.

[0013]

In order to achieve this object, the present invention provides a step of forming a conductor pattern of a printed wiring board, a high-sensitivity photosensitive ink applied on the printed wiring board, and a drying step. The step of forming the first photosensitive layer and the first step
Forming a second photosensitive layer by coating a photosensitive ink having the same main component as the photosensitive ink but different color tone and low sensitivity on the photosensitive layer and drying to form the first and second photosensitive layers. The method comprises exposing a mask film having a desired shape with a difference in photographic density and developing it to simultaneously form a solder resist and a road map.

[0014]

With this configuration, it becomes possible to omit the steps of applying the photosensitive solder resist ink, drying the touch, aligning the solder resist forming mask film, exposing and developing, and applying the first photosensitive ink. , Touch dry,
After the second photosensitive ink is applied and dried by touching the finger, the mask film is exposed to ultraviolet light and developed at the same time. Therefore, the positional relationship between the solder resist and the road map can be maintained in the designed state. The formation of significant irregularities between the photosensitive roadmap ink after application and the photosensitive solder resist ink, the insulating substrate and the surface of the conductor pattern is suppressed, and the close contact with the mask film during exposure is maintained. It is possible to prevent the ultraviolet diffraction phenomenon at the mask film shielding part,
The shape of the mask film can be accurately reproduced with the solder resist and the roadmap shape after development and formation.

[0015]

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

1 (a), (b), (c) and (d),
1 shows a manufacturing process of a printed wiring board according to a first embodiment of the present invention. In FIG. 1, 11 is an insulating substrate,
12 is a conductor pattern, 13 is a highly sensitive photosensitive ink, 1
4 is a low-sensitivity photosensitive ink, 15 is a mask film, 1
6 is a solder resist and 17 is a road map.

The formation of the solder resist and the road map of the printed wiring board constructed as above will be described.

First, a solder resist and a roadmap forming mask film used for manufacturing a usual printed wiring board are prepared. A negative pattern is prepared for the solder resist forming mask film, and a positive pattern is prepared for the road map forming mask film.

Next, a negative pattern of a mask film for forming a solder resist is first brought into close contact with an unexposed film having a photosensitive layer coated on a polyester film, exposed under normal exposure conditions, and then a mask for forming a road map. A positive pattern of the film is brought into close contact with the same position, exposed under a condition of about 1/3 to 1/5 of a normal exposure amount, and developed under a normal condition to obtain a mask film 15 having a photographic density difference.

After that, the conductor pattern 1 is formed on the insulating substrate 11.
The highly sensitive photosensitive ink 13 of alkali developing type is applied onto the printed wiring board on which the 2 is formed by means of screen printing, a roll coater or a curtain coater, and the temperature is 60 to 85 ° C. in a hot air circulation tank for a time. Dry by touch under the condition of about 15 to 30 minutes.

Next, as shown in FIG. 1 (b), the low-sensitivity photosensitive ink 14 is applied onto the low-sensitivity photosensitive ink 13 in the same manner as the high-sensitivity photosensitive ink 13 and dried by touch with a finger. Then, as shown in FIG. 1 (c), a mask film 15 prepared in advance is brought into close contact with the surface of the high-sensitivity photosensitive ink 13 and exposed to ultraviolet light under the condition of an exposure amount of about 900 to 1100 mJ / cm ^2. To do. Here, the ultraviolet rays are shielded at a portion having a large exposure amount when the mask film is formed, that is, at a portion where the solder resist is formed, and the low-sensitivity photosensitive ink 14
Is not exposed, only the high-sensitivity photosensitive ink 13 is exposed,
When the mask film is formed, the exposure amount is small, or the unexposed portion, that is, the roadmap forming portion, is transparently exposed to both the low-sensitivity photosensitive ink 14 and the high-sensitivity photosensitive ink 13.

Then, as shown in FIG. 1D, the unexposed portions of the low-sensitivity photosensitive ink 14 and the high-sensitivity photosensitive ink 13 are simultaneously developed and removed with a developer containing sodium carbonate as a main component. . After that, in a hot air circulation tank, etc.,
The final drying and curing is performed under the conditions of 30 to 160 ° C. and time of about 30 to 60 minutes to obtain the insulating substrate 11 and the conductor pattern 12.
To stabilize the adhesion between the solder resist 16 and the road map 17.

In the embodiment of the present invention as described above, compared with the conventional method of applying the photosensitive roadmap after developing and removing the unexposed portion of the photosensitive solder resist, the steps of forming the solder resist and the roadmap are performed. The required time is reduced to about half, and the relative positional relationship between the solder resist after formation and the roadmap was about 0.15 mm at maximum with the conventional method, but it was markedly improved as designed, and at the same time, the solder resist after formation was improved. The recall ratio of the road map to the mask film can be improved from 60 to 100% to 90 to 100%.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a cross-sectional view of the manufacturing process of a printed wiring board showing the second embodiment of the present invention. In FIG. 2, 11 is an insulating substrate, 12 is a conductor pattern, 13 is a high-sensitivity photosensitive ink, 14 is a low-sensitivity photosensitive ink, 16 is a solder resist, 17 is a roadmap, and the above is the configuration of FIG. It is similar. The difference from the configuration of FIG. 1 is a method of producing a mask film 15, which is used to produce a solder resist and a mask film for forming a roadmap, which are used in the production of a normal printed wiring board, and a mask film for forming a solder resist and a roadmap. Prepare a negative pattern on the mask film for formation, to the unexposed film coated with the photosensitive layer on the polyester film, first adhere the negative pattern of the mask film for solder resist formation, and expose under normal exposure conditions, then The negative pattern of the mask film for forming the roadmap is closely attached at the same position, exposed under the condition of about 1/3 to 1/5 of the normal exposure amount, and developed under the normal condition to give a difference in photographic density. Is.

A solder resist and a road map forming method for the printed wiring board having the above-described structure will be described. First, as shown in FIG. 2 (a), using a method similar to that of Example 1, an alkaline developing type high-sensitivity photosensitive ink 13 was formed on a printed wiring board on which a conductor pattern 12 was formed on an insulating substrate 11. It is applied using a means such as screen printing, a roll coater or a curtain coater, and dried by touch with a hot air circulating tank under the conditions of a temperature of 60 to 85 ° C. and a time of about 15 to 30 minutes.

Next, as shown in FIG. 2B, the low-sensitivity photosensitive ink 14 is applied in the same manner as the high-sensitivity photosensitive ink 13 and is dried by touch with a finger. Then, as shown in FIG. 2 (c), a mask film 15 having a photographic density difference was used to bring it into close contact with the surface of the low-sensitivity photosensitive ink 14 and to obtain high sensitivity at an exposure dose of about 900 to 1100 mJ / cm ^2. The photosensitive ink and the low-sensitivity photosensitive ink are exposed to ultraviolet light at the same time.
As shown in (d), the unexposed portions of the low-sensitivity photosensitive ink 14 and the high-sensitivity photosensitive ink 13 are developed and removed with a developing solution containing sodium carbonate as a main component. After that, final curing is performed in a hot air circulation tank or the like at a temperature of 130 to 160 ° C. for a time of about 30 to 60 minutes to stabilize the adhesion to the insulating substrate 11, the solder resist 16, and the road map 17.

By changing the method of forming the mask film 15 as described above, it is possible to form an insulating coating having a high insulating property and excellent coating strength on the surface of the printed wiring board.

In the embodiment of the present invention, the structure of the printed wiring board is a single-sided printed wiring board, but it may be a double-sided or multi-layered printed wiring board, and the photosensitive ink 13 having high sensitivity and low photosensitivity. Although the ink 14 is of the alkali development type, it goes without saying that it may be of the solvent development type.

[0029]

INDUSTRIAL APPLICABILITY As described above, the present invention uses two kinds of photosensitive inks of the same main component having different sensitivities and simultaneously exposes them to ultraviolet rays simultaneously with one mask film having a photographic density difference.
By developing, it is possible to significantly improve the manufacturing yield and productivity of the printed wiring board in the solder resist and roadmap formation process, and realize a printed wiring board with excellent relative positional accuracy and shape reproducibility of the solder resist and roadmap. Is.

[Brief description of drawings]

1A to 1D are cross-sectional views of a main part process in a method for manufacturing a printed wiring board according to a first embodiment of the present invention.

2A to 2D are cross-sectional views of a main part process in a method of manufacturing a printed wiring board according to a second embodiment of the present invention.

3 (a) to (f) are cross-sectional views of a main process in a conventional method for manufacturing a printed wiring board.

[Explanation of symbols]

11 Insulating substrate 12 conductor pattern 13 Highly sensitive photosensitive ink 14 Low-sensitivity photosensitive ink 15 Mask film 16 Solder resist 17 Roadmap

Claims (2)

[Claims] 1. A step of forming a conductor pattern of a printed wiring board, a step of applying a high-sensitivity photosensitive ink on the printed wiring board and drying to form a first photosensitive layer, and the first step. Forming a second photosensitive layer by coating on the photosensitive layer a photosensitive ink having the same main component as the photosensitive ink but having a different color tone and low sensitivity, and drying to form the second photosensitive layer; A method for manufacturing a printed wiring board, which comprises a step of simultaneously forming a solder resist and a road map by exposing and developing with a mask film having a desired shape and a difference in photographic density. 2. A mask film used for exposing and developing a plurality of photosensitive layers having different sensitivities and having a photographic density difference.