JP3019503B2 - Manufacturing method of printed wiring board - Google Patents

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 for various electronic devices such as a personal computer and a word processor.

[0002]

2. Description of the Related Art In recent years, printed wiring boards, which are widely used in various electronic devices, are becoming increasingly compact and lightweight, and have become more and more multifunctional. The lands on which conductive patterns and electronic components are formed on insulating substrates are becoming increasingly narrower, thinner and smaller, preventing solder from sticking to unnecessary parts, protecting the conductive patterns from oxidation, and maintaining insulation. Resists and roadmaps formed on printed wiring boards for the purpose of improving solderability and solderability are also required to have high resolution and high positional accuracy, and the formation method has changed from screen printing to photo development using mask films. It is replacing the law.

Hereinafter, a conventional printed wiring board will be described. FIG. 3 shows a conventional manufacturing process for forming a solder resist and a road map by a photo-developing method on a printed wiring board.

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

[0005] The formation of the solder resist and the road map of the printed wiring board configured as described above will be described below.

First, an etching resist is formed on a copper-clad laminate (not shown) cut to a predetermined size by a screen printing method, a photo-developing method, or the like, and then using a solution such as cupric chloride. The conductor pattern 2 is formed by etching, and the etching resist is removed.

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 touch drying is performed by hot air or the like.

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

[0009] After that, it is treated again with hot air or the like to improve the adhesion and hardness to the insulating substrate and the conductor pattern.
A solder resist 3b and a road map 5b are formed on a printed wiring board.

[0010]

However, in the above-described conventional configuration, 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 is difficult. Touch drying, alignment of mask film 4 for solder resist formation, exposure, development, and photosensitive roadmap ink 5
a) coating, touch drying, positioning of the mask film 6 for forming a road map, exposure, development, and the manufacturing process are complicated and have a long time.
Therefore, it is difficult to maintain the relative positional accuracy between the formed solder resist 3b and the road map 5b because the steps of forming the road map 5b and the road map 5b are different.

Further, a photosensitive roadmap ink 5 is formed on the solder resist 3b having the uneven surface after development and formation.
As a result, the photosensitive roadmap ink 5a and the surface of the solder resist 3b, the surface of the insulating substrate 1 and the surface of the conductive pattern 2 are unevenly formed. For this reason, a sufficient adhesion state with the road map forming mask film 6 at the time of exposure cannot be maintained, which causes a diffraction phenomenon of ultraviolet rays at the mask film shielding portion, and the shape of the road map 5b after development and formation is in a designed state. If the shape of the mask film is not reproduced, characters and symbols cannot be read when the shape is remarkable, and the yield of printed wiring board production in the road map forming process is deteriorated.

The present invention solves the above-mentioned conventional problems, and significantly improves the production yield and productivity of a printed wiring board in a step of forming a solder resist and a road map using a photosensitive solder resist ink and a photosensitive road map ink. It is an object of the present invention to provide a printed wiring board excellent in relative positional accuracy between a solder resist and a road map and reproducibility of a shape.

[0013]

In order to achieve this object, the present invention comprises a step of forming a conductive pattern on a printed wiring board, and a step of applying a high-sensitivity photosensitive ink on the printed wiring board and drying the ink. Forming a first photosensitive layer;
Forming a second photosensitive layer by applying a photosensitive ink having the same main component as the photosensitive ink but having a different color tone and a low sensitivity on the photosensitive layer, followed by drying to form the first and second photosensitive layers. Forming a solder resist and a road map at the same time by exposing and developing with a mask film having a desired density and a photographic density difference.

[0014]

With this structure, it is possible to omit the application of the photosensitive solder resist ink, the drying of the touch, the alignment of the mask film for forming the solder resist, the exposure and the development steps, and the application of the first photosensitive ink. , Touch dry,
After the application of the second photosensitive ink and the drying of the touch, it is possible to maintain the positional relationship between the solder resist and the roadmap in the designed state because the mask is exposed and developed with one mask film at the same time. The occurrence of significant unevenness between the photosensitive roadmap ink after application of the photosensitive roadmap ink and the photosensitive solder resist ink, the surface of the insulating substrate or conductor pattern is suppressed, and the close contact with the mask film during exposure is maintained. Can hardly cause the ultraviolet diffraction phenomenon in the mask film shielding part,
The shape of the solder resist and roadmap after development and formation can accurately reproduce the shape of the mask film.

[0015]

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

FIGS. 1 (a), (b), (c), (d)
FIG. 3 shows a process of manufacturing a printed wiring board according to the first embodiment of the present invention. In FIG. 1, 11 is an insulating substrate,
12 is a conductor pattern, 13 is a photosensitive ink of high sensitivity, 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 configured as described above will be described.

First, a solder resist and a mask film for forming a road map, which are used for manufacturing a normal printed wiring board, are prepared. The mask film for forming a solder resist prepares a negative pattern, and the mask film for forming a road map prepares a positive pattern.

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

Thereafter, the conductor pattern 1 is placed on the insulating substrate 11.
2 is applied on the printed wiring board formed with 2 by using screen printing, means such as a roll coater or a curtain coater, and the temperature is 60 to 85 [deg.] C. in a hot air circulation tank. Dry to the touch under conditions of about 15 to 30 minutes.

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

Then, as shown in FIG. 1 (d), the unexposed portions of the low-sensitivity photosensitive ink 14 and the high-sensitivity photosensitive ink 13 are simultaneously developed and removed with a developing solution containing sodium carbonate as a main component. . After that, the temperature is set to 1 in a hot air circulation tank, etc.
The final drying and curing are performed under the conditions of 30 to 160 ° C. and the time of about 30 to 60 minutes, and the insulating substrate 11 and the conductive pattern 12 are formed.
And the solder resist 16 and the road map 17 in close contact with each other.

In the embodiment of the present invention as described above, a solder resist and a road map forming step are compared with a conventional method of applying a photosensitive road map after developing and removing an unexposed portion of the photosensitive solder resist. The required time is reduced by about half, and the relative positional relationship between the formed solder resist and the road map is about 0.15 mm at the maximum by the conventional method. And the recall of the road map with respect to the mask film can be improved from 60 to 100% to 90 to 100%.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a cross-sectional view showing a process of manufacturing a printed wiring board according to a second embodiment of the present invention. In FIG. 2, reference numeral 11 denotes an insulating substrate, 12 denotes a conductor pattern, 13 denotes a high-sensitivity photosensitive ink, 14 denotes a low-sensitivity photosensitive ink, 16 denotes a solder resist, and 17 denotes a road map. It is similar. 1 is different from the configuration of FIG. 1 in a method of forming a mask film 15, in which a solder resist and a mask film for forming a road map used for manufacturing a normal printed wiring board are formed, and a mask film for forming a solder resist and a road map are formed. Prepare a negative pattern on the mask film for formation, first adhere the negative pattern of the mask film for solder resist formation to the unexposed film coated with the photosensitive layer on the polyester film, and expose under normal exposure conditions, A negative pattern of a mask film for forming a road map is brought into close contact with the same position, exposed under conditions of about 1/3 to 1/5 of a normal exposure, developed under normal conditions, and provided with a photographic density difference. It is.

A method of forming a solder resist and a road map of the printed wiring board configured as described above will be described. First, as shown in FIG. 2A, using a method similar to that of the first embodiment, a highly sensitive photosensitive ink 13 of an alkali developing type is applied on a printed wiring board having a conductive pattern 12 formed on an insulating substrate 11. It is applied by means of screen printing, a roll coater, a curtain coater, or the like, and touch drying is performed in a hot air circulating tank or the like at a temperature of 60 to 85 ° C. for about 15 to 30 minutes.

Next, as shown in FIG. 2B, a low-sensitivity photosensitive ink 14 is applied in the same manner as the high-sensitivity photosensitive ink 13, and touch drying is performed. Then, as shown in FIG. 2 (c), a low-sensitivity photosensitive ink 14 is brought into close contact with a mask film 15 having a photographic density difference, and a high-sensitivity light is exposed at an exposure amount of about 900 to 1100 mJ / cm ^2. The photosensitive ink and the low-sensitivity photosensitive ink were simultaneously exposed to ultraviolet light, and FIG.
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 developer containing sodium carbonate as a main component. Thereafter, 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 with 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 as described above, it is possible to form an insulating film having high insulation properties and excellent film strength on the surface of the printed wiring board.

In the embodiments 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 multilayer printed wiring board. Although the ink 14 is of the alkali development type, it goes without saying that the ink 14 may be of the solvent development type.

[0029]

As described above, according to the present invention, two types of photosensitive inks having the same main component having different sensitivities are used, and a single mask film having a photographic density difference is used for simultaneous exposure to ultraviolet light.
By developing, the production yield and productivity of the printed wiring board in the solder resist and road map formation process are remarkably improved, and a printed wiring board excellent in the relative positional accuracy of the solder resist and the road map and in the reproducibility of the shape can be realized. It is.

[Brief description of the drawings]

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

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

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

[Explanation of symbols]

 Reference Signs List 11 Insulating substrate 12 Conductive pattern 13 High-sensitivity photosensitive ink 14 Low-sensitivity photosensitive ink 15 Mask film 16 Solder resist 17 Road map

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 3/28 H05K 3/00

Claims (2)

(57) [Claims] A step of forming a conductive pattern on 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; A step of applying a photosensitive ink having the same main component as the photosensitive ink but having a different color tone and a low sensitivity on the photosensitive layer and drying to form a second photosensitive layer; and forming the first and second photosensitive layers. Forming a solder resist and a road map at the same time by exposing and developing with a mask film having a photographic density difference in a desired shape. 2. A film having a photosensitive layer and a negative pattern
Solder mask formation mask film
Closely contact and expose with the proper exposure amount, the solder resist type
Separate the mask film for formation, then draw a positive pattern
The filled roadmap forming mask film
At an exposure of 3/1 to 1/5 of the appropriate exposure.
Exposure and pull the mask film for roadmap formation
Printed wiring board created by developing after release
Exposure mask film.