JP3755193B2 - Method and apparatus for manufacturing printed wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a printed wiring board used in various electronic devices and the like and an apparatus for manufacturing the same.
[0002]
[Prior art]
In recent years, printed wiring boards that are widely used in various electronic devices, etc., are formed on an insulating substrate due to the remarkable increase in wiring density and surface mounting of electronic components as electronic devices become smaller and multifunctional. Lands on which conductor patterns and electronic components are mounted are becoming increasingly narrow pitch, thinner and smaller, prevent solder adhesion on parts that do not require soldering, protect the conductor pattern against oxidation, maintain insulation, improve solderability, etc. For this purpose, the solder resist formed on the printed wiring board is required to have high resolution and high positional accuracy, and the formation method has changed from the screen printing method to the photographic development method using a mask film.
[0003]
Hereinafter, a conventional method for manufacturing a printed wiring board will be described with reference to the drawings.
4A to 4C are cross-sectional views showing a conventional printed wiring board manufacturing method, and FIG. 5 is a schematic view showing a conventional printed wiring board manufacturing apparatus.
[0004]
4 and 5, 21 is a printed wiring board, 22 is an insulating substrate, 23 is a conductor pattern, 24 is a photosensitive solder resist ink that is a photosensitive material, 25 is a solder resist, 26 is a mask film, 27 is an ultraviolet ray, 28 Is a drying furnace, 29 is an exposure unit, 30 is a positioning unit, and 31 is a development unit.
[0005]
The formation of the solder resist of the printed wiring board configured as described above will be described in detail below. First, after forming an etching resist on a copper clad laminate (not shown) cut to a predetermined size by a known screen printing method or photographic method, etching is performed using a solvent such as cupric chloride. Conductive pattern 23 is formed. Next, as shown in FIG. 4A, a photosensitive solder resist ink 24 is applied to the printed wiring board 21 on which the conductor pattern 23 is formed on the insulating substrate 22, and the touch is dried with hot air in a drying furnace. And leave or cool.
[0006]
Next, as shown in FIG. 4 (b), the solder resist forming mask film 26 is brought into vacuum contact with the surface of the photosensitive solder resist ink 24 that has been dried and cooled by touching, and is aligned by the positioning unit 30 shown in FIG. Then, the exposure unit 29 is exposed to ultraviolet rays 27 having a light quantity of 400 to 500 mJ / cm ² , and then the unexposed part is developed and removed with a predetermined developer in the developing unit 31, and about 140 to 150 ° C., 50 to 60 ° C. The main curing is performed under hot air conditions for a minute to form a solder resist 25.
[0007]
[Problems to be solved by the invention]
However, in the above conventional configuration, although the formed solder resist 25 has high resolution, there are very many manufacturing processes such as application of the photosensitive solder resist ink 24, touch drying, standing cooling, exposure, development, recuring and the like. Among the manufacturing processes, the exposure process is complicated, such as the positioning of the solder resist forming mask film 26 and the printed wiring board 21, vacuum adhesion, UV irradiation, and release of the vacuum, the peeling of the mask film for forming the solder resist, and installation until development. In addition, many processes are required, and the productivity is low compared with the screen printing method.
[0008]
Thus, various measures for improving productivity in the photographic development method have been studied, and as one of them, as disclosed in JP-A-6-45735, heating is performed immediately after exposure of the photosensitive solder resist. Although there is a method to improve productivity, there is a possibility that line thickening is likely to occur after development, and resolution may be reduced. To prevent this, if the exposure amount and the heat amount of heating are reduced, the development is reversed. There was a possibility that undercut would occur later.
[0009]
It can be inferred from the following. In general, a photosensitive solder resist undergoes a photopolymerization reaction by ultraviolet rays at the time of exposure. First, the photopolymerization initiator in the photosensitive solder resist component is cleaved into radicals (intermediate active substances) and the monomer is also cleaved and activated. Next, a growth reaction / chain transfer reaction occurs to increase the crosslinking density, and finally there is a termination reaction.
[0010]
For this reason, heating is started immediately after exposure to delay the start of the termination reaction, and the fractional growth reaction / chain transfer reaction is promoted to promote photopolymerization, thereby improving productivity. This is a phenomenon that is promoted only in the portion exposed through the mask film and irradiated with ultraviolet rays. During exposure, if UV rays pass through the photosensitive solder resist and reach the surface of the insulating substrate, curing proceeds to the part that should become the unexposed part when the photopolymerization is delayed due to the termination reaction being delayed by heating after exposure. , There is a possibility of line thickening after development.
[0011]
On the contrary, if the amount of ultraviolet rays at the time of exposure is insufficient, the ultraviolet rays that have passed through the surface of the photosensitive solder resist will not reach the surface of the insulating substrate. Undercutting may occur.
[0012]
Therefore, for the above reason, it is necessary to set the amount of ultraviolet light at the time of exposure to an amount of light just before passing through the photosensitive solder resist and reaching the surface of the insulating substrate. Actually, the amount of ultraviolet light is 70 to 80% of the appropriate amount of exposure. Therefore, it is insufficient as a method for significantly improving productivity, and it is also a complicated method for setting an exposure amount and heating conditions and managing process conditions.
[0013]
The present invention solves the above-mentioned conventional problems, stably improves the resolution after development of the photosensitive solder resist, increases the productivity of the solder resist formation process further than the conventional method, and increases the yield of the manufacturing process. It is an object of the present invention to provide a printed wiring board manufacturing method and a manufacturing apparatus for the same that can significantly improve the reliability of electronic equipment.
[0014]
[Means for Solving the Problems]
In order to solve this problem, the present invention includes a step of applying a photosensitive solder resist on the insulating substrate on which a conductor pattern is formed and touch-drying, a step of heating or irradiating light or heat rays immediately before exposure, a mask This is a method having a step of exposing a film in vacuum contact with a substrate and a step of developing an unexposed portion.
[0015]
By this method, productivity can be improved and yield can be improved.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 of the present invention includes a step of applying a photosensitive material on an insulating substrate on which a conductive pattern is formed and touch-drying, a step of heating or irradiating light or heat rays immediately before exposure, It is a method for producing a printed wiring board having a step of exposing a mask film to a printed wiring board by vacuum adhesion and a step of developing an unexposed portion. A photosensitive material is applied to the printed wiring board and touched. After drying, the photosensitive material is activated by heating or irradiating light or heat rays immediately before exposure, and the mask film is vacuum-adhered and exposed with a low exposure amount of ultraviolet light for development. This has the effect of improving productivity and resolution.
[0017]
Invention of Claim 2 of this invention is a manufacturing method of the printed wiring board of Claim 1 which irradiates a photosensitive material with the ultraviolet-ray of a low exposure amount, The ultraviolet-ray of a low exposure amount is just before exposure. By irradiating and activating the photosensitive material, the reaction in the exposure is promoted, and the exposure can be performed with a low exposure amount and a short exposure time, thereby improving the productivity.
[0018]
Invention of Claim 3 of this invention is a manufacturing method of the printed wiring board of Claim 2 which irradiates a photosensitive material by the ultraviolet-ray amount within 50% of the appropriate exposure amount of a photosensitive material, By irradiating the photosensitive material with an ultraviolet ray amount within 50% of the appropriate exposure amount, which is the developable ultraviolet ray amount, the photosensitive material is activated, and at the same time, the exposure can be performed at a low exposure amount, and also the remaining development is prevented. Has an effect.
[0019]
Invention of Claim 4 of this invention is set as the manufacturing method of the printed wiring board of Claim 1 which irradiates a photosensitive material with infrared rays or near infrared rays, and irradiates with infrared rays or near infrared rays just before exposure. Thus, the photosensitive material is activated by light and heat, and at the same time, it can be exposed with a low exposure time, thereby improving the productivity.
[0020]
The invention according to claim 5 of the present invention is a method for producing a printed wiring board according to claim 1, wherein the photosensitive material is heated with a dry gas having a low humidity and heated. The material is activated by heating at the same time, and the dryness to the touch is improved, and the solder resist ink for photographic development on the printed wiring board at the time of releasing the vacuum after exposure adheres to the mask film for forming the solder resist. At the same time, the exposure can be performed with a low exposure amount and a short exposure time, thereby improving the productivity.
[0021]
The invention according to claim 6 of the present invention is that the conductive substrate is formed with a conductive pattern, and the photosensitive substrate is coated and dried by touching the insulating substrate, and the printed wiring board immediately before exposure is heated or irradiated with light or heat rays. And a printed wiring board manufacturing apparatus including an exposure unit that exposes the printed wiring board to ultraviolet light, and includes a heating unit that heats the photosensitive material immediately before exposure or an irradiation unit that irradiates light or heat rays. This is an apparatus, and has the effect of reducing the exposure time and improving the productivity.
[0022]
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
1A to 1D are cross-sectional views showing a method for manufacturing a printed wiring board according to an embodiment of the present invention, and FIG. 2 shows a method for manufacturing a printed wiring board according to an embodiment of the present invention. FIG. 3 is a cross-sectional view, and FIG. 3 is a schematic diagram showing a printed wiring board manufacturing apparatus according to an embodiment of the present invention.
[0023]
1-3, 1 is a printed wiring board, 2 is an insulating substrate, 3 is a conductor pattern, 4 is a photosensitive solder resist ink as a photosensitive material, 5 is a solder resist, 6 is a mask film, and 7 is an irradiated portion. UV is 8 in the exposure unit, 9 is a dry gas in the heating unit, 10 is a drying unit, 11 is a positioning unit, 12 is a heating unit or irradiation unit, 13 is an exposure unit, and 14 is a development unit. is there.
[0024]
As shown in FIG. 3, the printed wiring board manufacturing apparatus according to the present invention includes a heating unit or an irradiation unit 12 immediately before the exposure unit 13 after the positioning unit 11.
[0025]
The method for manufacturing a printed wiring board according to the present invention will be described in detail below using the printed wiring board manufacturing apparatus configured as described above.
[0026]
First, a photosensitive solder resist ink 4 is applied on a printed wiring board 1 having a conductor pattern 3 formed on an insulating substrate 2 by a known means such as screen printing, a roll coater or a curtain coater, and the drying shown in FIG. Touch drying is performed in the part 10 under conditions of a temperature of 60 to 80 ° C. and a time of about 15 to 30 minutes to obtain a printed wiring board 1 as shown in FIG. Next, the positioning unit 11 shown in FIG. 3 performs positioning with a CCD camera, and the irradiation unit 12 conveys the printed wiring board 1 to the exposure unit 13 while being 300 mJ / cm ² which is an appropriate exposure amount of the photosensitive solder resist ink 4. Is irradiated and heated with an ultraviolet ray amount of 120 to 150 mJ / cm ² corresponding to an exposure amount of about 50 to 50%, preferably about 40 to 50% (FIG. 1B).
[0027]
Next, after the mask film 6 and the printed wiring board 1 are brought into vacuum contact with each other in the exposure section 13 of FIG. 3, as shown in FIG. 1 (c), 90 to 120 mJ / cm corresponding to 30 to 40% of the appropriate exposure amount. After performing ultraviolet exposure at an exposure amount of ^2, the unexposed portion is developed and removed with a 1 wt% sodium carbonate developer to form a printed wiring board 1 as shown in FIG. Thereafter, main curing is performed in a hot-air circulating furnace or the like to improve coating film properties such as adhesion between the insulating substrate 2, the conductor pattern 3 and the solder resist 5. The solder resist 5 of the printed wiring board manufactured by the above method has high resolution without causing line thickening or development residue.
[0028]
In addition to the above-described heating method using ultraviolet rays, it is also possible to perform heating using near infrared rays or far infrared rays. Further, as shown in FIGS. To improve the touch-drying property of the solder resist surface by heating, and to eliminate the tackiness that occurs when the mask film 6 and the printed wiring board 1 are in close contact with each other at the time of exposure, thereby improving productivity and process yield. Is also possible.
[0029]
【The invention's effect】
As described above, the present invention has an effect that the formation of a solder resist of a printed wiring board by a photographic development method can be produced with high productivity and high resolution and high yield.
[Brief description of the drawings]
FIGS. 1A to 1D are cross-sectional views showing a method of manufacturing a printed wiring board according to an embodiment of the present invention. FIGS. 2A to 2D are diagrams illustrating an embodiment of the present invention. Sectional drawing which shows the manufacturing method of a printed wiring board [FIG. 3] Schematic which shows the manufacturing apparatus of the printed wiring board in one embodiment of this invention [FIG. 4] (a)-(c) is the conventional printed wiring board. FIG. 5 is a cross-sectional view showing a manufacturing method. FIG. 5 is a schematic diagram showing a conventional printed wiring board manufacturing apparatus.
DESCRIPTION OF SYMBOLS 1 Printed wiring board 2 Insulation board 3 Conductive pattern 4 Photosensitive solder resist ink 5 Solder resist 6 Mask film 7 Ultraviolet rays 8 in an irradiation part Ultraviolet rays 9 in an exposure part Drying gas 10 Drying part 11 Positioning part 12 Heating part or irradiation part 13 Exposure unit 14 Development unit

Claims (6)

Applying a photosensitive material on an insulating substrate on which a conductive pattern is formed, touching and drying it, heating the photosensitive material just before exposure or irradiating it with light or heat, and mask film on a printed circuit board A method for producing a printed wiring board, comprising: a step of vacuum-contacting and exposing; and a step of developing an unexposed portion. The method for producing a printed wiring board according to claim 1, wherein the photosensitive material is heated or irradiated with a low exposure ultraviolet ray. The method for producing a printed wiring board according to claim 2, wherein the photosensitive material is irradiated with an ultraviolet ray amount within 50% of an appropriate exposure amount of the photosensitive material. The method for producing a printed wiring board according to claim 1, wherein the photosensitive material is irradiated with infrared rays or near infrared rays. The method for producing a printed wiring board according to claim 1, wherein the photosensitive material is heated with a dry gas having a low humidity. A printed wiring board transport and positioning unit in which a conductive pattern is formed and a photosensitive material is applied and dried by touch, a printed wiring board immediately before exposure or means for irradiating light or heat rays, and the printed wiring board is exposed to ultraviolet rays. A printed wiring board manufacturing apparatus including an exposure unit.

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