JP3606053B2 - Method 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 such as a personal computer, a mobile communication telephone, and a video camera.
[0002]
[Prior art]
In recent years, as electronic devices have higher functionality and higher density, electronic components are increasingly becoming smaller, more integrated, and faster.
[0003]
For this reason, the printed wiring board is becoming increasingly low in dielectric constant, thin, and light in weight, and the wiring density is also increased. Even for the solder resist that covers this wiring pattern, the fine wire coverage and uniformity At the same time, improvement in soldering reliability of component mounting parts has been demanded.
[0004]
A conventional method for manufacturing a printed wiring board will be described below.
[0005]
A circuit pattern is formed on the metal layers on the front and back surfaces of the substrate using means such as etching. Next, an ultraviolet curable solder resist ink is applied to the printed wiring board on which the circuit pattern is formed. As a coating method here, first, a positive or negative charge is charged on the entire surface of the printed wiring board via a conveying jig or the like.
[0006]
On the other hand, the solder resist ink is charged with a charge opposite to that of the printed wiring board through a spray nozzle or the like. Then, the solder resist ink is applied to the entire surface of the printed wiring board by being discharged from the tip of the spray nozzle onto the surface of the printed wiring board.
[0007]
At this time, in addition to the spraying force of the solder resist ink, the electrostatic attraction generated along the electric lines of force generated between the charge charged to the solder resist ink and the opposite charge charged to the printed wiring board. Can be applied to the printed wiring board. Thereafter, similarly, a solder resist ink is applied to the opposite surface of the printed wiring board. The solder resist ink thus applied to both sides of the printed wiring board is then temporarily cured, for example, by drying at 80 ° C. for about 20 minutes.
[0008]
Then, through a negative pattern exposure film, a necessary portion is selectively photopolymerized and exposed in an exposure process by ultraviolet irradiation. At this time, the end-exposed portion is dissolved in the subsequent development process using an aqueous sodium carbonate solution or the like, and the exposed portion remains on the substrate surface without being dissolved.
[0009]
Finally, the solder resist is thermally cured by, for example, heat treatment at 150 ° C. for about 1 hour to complete the solder resist formation. Thereafter, parts drawing printing, gold plating, outline processing, etc. are performed as necessary to complete the printed wiring board.
[0010]
In the above description, the exposure process will be described in more detail with reference to the drawings.
[0011]
FIG. 3 is a cross-sectional view showing a conventional method for manufacturing a printed wiring board. In FIG. 3, 11 is an ultraviolet ray, 12 is an acrylic plate, 13 is an exposure film, 14 is an exposure table, 15 is a printed wiring board, and 16 is a solder resist.
[0012]
A method for manufacturing the printed wiring board configured as described above will be described.
[0013]
The printed wiring board 15 coated with the solder resist 16 on the surface and dried is aligned between the exposure table 14 and the exposure film 13 and then set. The exposure film 13 is bonded to the acrylic plate 12 in advance. Next, the adhesiveness between the printed wiring board 15 and the exposure film 13 is enhanced by evacuating the space between the acrylic board 12 holding the printed wiring board 15 and the exposure table 14. Thereafter, the ultraviolet rays 11 are irradiated from the acrylic plate 12 side perpendicularly to the solder resist 16 on the surface of the printed wiring board 15. Similarly, exposure is performed on the opposite surface in the above-described procedure.
[0014]
Here, the exposure film 13 is composed of a light-shielding portion and a non-light-shielding portion according to the pattern shape of the pattern in which the solder resist 16 is to be finally left. The portion of the solder resist 16 irradiated with the ultraviolet rays 11 through the exposure film 13 is photopolymerized and is not dissolved in the next development process, and conversely, the solder resist of the unexposed portions not irradiated with the ultraviolet rays 11 is the next. A predetermined pattern is obtained by completely dissolving and removing in the developing step.
[0015]
[Problems to be solved by the invention]
However, in the above conventional printed wiring board manufacturing method, when applying the solder resist ink to the surface of the printed wiring board, the solder resist ink is also applied to the end face which is a cut surface around the printed wiring board. Become. When the periphery of the printed wiring board is exposed in the exposure step, the solder resist ink applied to the end face is simultaneously irradiated with ultraviolet rays and exposed.
[0016]
Since the ultraviolet rays irradiated here are perpendicularly incident on the surface of the printed wiring board, it is not directly irradiated onto the solder resist on the end surface portion of the printed wiring board, but the ultraviolet rays are scattered and scattered at the end surface portion. It will be done indirectly by light. Therefore, the exposure state of the end face part is very unstable and becomes a semi-exposure and semi-polymerized state, and the solder resist at the end face part is in a semi-exposure state in the subsequent development process, but it is not dissolved, but the adhesive force is weak and easily peeled Become.
[0017]
As a result, when the printed wiring board is transported in the development process, the semi-polymerized solder resist peeled off from the end face adheres to the transport conveyor and the liquid draining roll unit equipped in each of the development, washing and drying facilities. However, this reattaches to the soldered portion of the circuit pattern on the surface of the printed wiring board which has been transported later, and there is a problem in that poor soldering occurs when various chip components are mounted.
[0018]
If a half-exposure solder resist is mixed in the developer in the development booth, it will not be dissolved by the developer and will accumulate as foreign matter in the developer. It has the problem of causing deterioration and contamination of the developing equipment.
[0019]
The present invention solves the above-mentioned conventional problems, and does not generate a semi-exposed solder resist in the development process of solder resist formation, and a method for producing a printed wiring board with improved soldering reliability during component mounting The purpose is to provide.
[0020]
[Means for Solving the Problems]
In order to achieve this object, the present invention includes a step of applying a solder resist ink on both sides and end faces of a printed wiring board by an electrostatic spray coater method, a step of drying the solder resist ink, and an end face of the printed wiring board. A step of closely attaching an exposure film having a light-shielding portion having an area of 0.1 mm or more on the inside and 0.5 mm or more on the outside to the printed wiring board; exposing the printed wiring board by ultraviolet irradiation through the exposure film; A printed wiring board is manufactured by a method for manufacturing a printed wiring board, which includes a step of developing and removing the solder resist applied to the end face of the unexposed portion where no irradiates.
[0021]
According to the present invention, it is possible to obtain a printed wiring board manufacturing method that does not generate a solder resist in a semi-exposure state in the developing process for forming a solder resist and has improved soldering reliability during component mounting.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
The invention described in claim 1 of the present invention includes a step of applying a solder resist ink to both surfaces and end surfaces of a printed wiring board by an electrostatic spray coater method, a step of drying the solder resist ink, and an end surface of the printed wiring board. A step of closely adhering an exposure film having a light shielding portion of 0.1 mm or more on the inside and 0.5 mm or more on the outside to the printed wiring board; and a step of exposing the printed wiring board by ultraviolet irradiation through the exposure film; It is a method for manufacturing a printed wiring board comprising a step of developing and removing the solder resist applied to the end face of the unexposed part that is not irradiated with ultraviolet rays. With this configuration, the solder resist on the end face of the printed wiring board Since it is not irradiated with UV light and is not photopolymerized, it can be completely dissolved and removed during the development process. Without adhering semi exposure state bare and draining roll, an effect that can form a solder resist in a necessary portion of the printed wiring board surface.
[0023]
In addition, this configuration allows the outer periphery of the printed wiring board to be shielded from ultraviolet rays by the film used during exposure, and the solder resist on the end face is not irradiated with ultraviolet rays, so it can be completely dissolved and removed in the development process. It has the effect that a solder resist can be formed in a necessary portion without affecting the internal product portion other than the outer peripheral portion of the printed wiring board.
[0024]
Also, with this configuration, the printed circuit board end face part shields light on the exposure film from the end face to the inside at least 0.1 mm, so the end face part can be taken into consideration even when the exposure misalignment between the exposure film and the printed circuit board is taken into account. UV light is no longer irradiated. In addition, since at least 0.5mm from the end face is shielded from light on the exposure film, the part exposed to the outside of the end face is not irradiated with UV light within a distance of 0.5mm. However, there is no fear of irradiation, and it has the effect that it can be completely dissolved and removed in the development process.
[0025]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.
[0026]
1 and 2 are cross-sectional views showing a method for manufacturing a printed wiring board according to an embodiment of the present invention. In FIG. 1, the end face solder resist can be completely removed in the next exposure process by shielding the exposure film corresponding to the end face portion of the printed wiring board. In FIG. 2, the solder resist on the end face of the printed wiring board can be removed. Has the effect of being fully irradiated with ultraviolet rays and capable of performing sufficient photopolymerization.
[0027]
1 and 2, reference numeral 1 denotes ultraviolet rays, 2 denotes an acrylic plate, 3 denotes an exposure film, 4 denotes a light shielding portion, 5 denotes an exposure table, 6 denotes a printed wiring board, and 7 denotes a solder resist.
[0028]
About the manufacturing method of the printed wiring board comprised as mentioned above, the operation | movement is demonstrated below.
[0029]
An ultraviolet curable solder resist ink is applied to a printed wiring board on which a circuit pattern is formed using means such as etching on the metal layers on the front and back sides of the substrate. As an application method here, an electrostatic spray coater method will be described as an example.
[0030]
First, a positive or negative charge is charged on the entire surface of the printed wiring board 6 through a conveying jig or the like. On the other hand, the solder resist ink is charged with a charge opposite to that of the printed wiring board through a spray nozzle or the like. Then, the solder resist ink is applied to the entire surface of the printed wiring board by being discharged from the tip of the spray nozzle onto the surface of the printed wiring board.
[0031]
At this time, in addition to the spraying force of the solder resist ink, the electrostatic charge generated along the electric lines of force generated between the electric charge charged to the solder resist ink and the opposite electric charge charged to the printed wiring board 6. It can apply | coat to the printed wiring board 6 by attractive force. Thereafter, similarly, a solder resist ink is applied to the opposite surface of the printed wiring board 6. The solder resist ink thus applied to both surfaces of the printed wiring board 6 is then temporarily cured by, for example, drying at 80 ° C. for about 20 minutes.
[0032]
Then, through a negative pattern exposure film, a necessary portion is selectively photopolymerized and exposed in an exposure process by ultraviolet irradiation. At this time, in FIG. 1, the printed wiring board 6 coated with the solder resist 7 on the surface and dried is positioned between the exposure table 5 and the exposure film 3 and then set. The exposure film 3 is previously bonded to the acrylic plate 2.
[0033]
Next, the adhesion between the printed wiring board 6 and the exposure film 3 is enhanced by evacuating the space between the acrylic board 2 holding the printed wiring board 6 and the exposure table 5. Thereafter, the ultraviolet rays 1 are irradiated from the side of the acrylic plate 2 perpendicularly to the solder resist 7 on the surface of the printed wiring board 6. Similarly, exposure is performed on the opposite surface in the above-described procedure.
[0034]
Here, the exposure film 3 is composed of a light-shielding portion and a non-light-shielding portion according to the pattern shape of the pattern in which the solder resist 7 is to be finally left. The portion of the solder resist 7 irradiated with the ultraviolet light 1 through the exposure film 3 is photopolymerized and is not dissolved in the next development process, and conversely, the solder resist of the unexposed portion not irradiated with the ultraviolet light 1 is the next. A predetermined pattern is obtained by completely dissolving and removing in the developing step. The portion of the exposure film 3 corresponding to the position of the end face of the printed wiring board 6 can block the ultraviolet ray 1 by providing the light shielding portion 4 as shown in the drawing, and the solder resist 7 applied to the end face is not irradiated with the ultraviolet ray 1.
[0035]
The light-shielding portion 4 is provided at least 0.1 mm, preferably 0.2 mm or more inward from the end face of the printed wiring board 6, so that the ultraviolet rays 1 are emitted from the printed wiring board even if the misalignment between the printed wiring board 6 and the exposure film 3 is taken into consideration. The end face of 6 is not irradiated. Further, the light shielding portion 4 is provided at least 0.5 mm, preferably 1.0 mm or more from the end surface of the printed wiring board 6 to the outside, so that the ultraviolet rays scattered and scattered outside the printed wiring board 6 can be taken into consideration. The portion of the solder resist 7 exposed at the end face is not irradiated with the ultraviolet rays 1.
[0036]
Further, in FIG. 2, by irradiating the end surface portion of the printed wiring board 6 with ultraviolet rays 1 obliquely from above, the vertical component of the ultraviolet rays 1 is directly applied to the solder resist 7 at the end surface portions according to the angle, and is sufficiently photopolymerized. Is done. Thereafter, in the next development step, the unexposed area is dissolved in a development process using an aqueous sodium carbonate solution and the exposed area remains on the substrate surface without being dissolved. Finally, the solder resist is thermally cured by, for example, heat treatment at 150 ° C. for about 1 hour to complete the solder resist formation. Thereafter, the printed wiring board 6 is completed by performing component drawing printing, gold plating, outer shape processing, and the like as necessary.
[0037]
As described above, according to the present embodiment, the solder resist 7 applied to the end face of the printed wiring board 6 is completely removed in the next development process by not irradiating the ultraviolet ray 1 at all, or the ultraviolet ray 1 is sufficiently absorbed. Prints with improved soldering reliability during component mounting without generating a semi-exposed solder resist in the development process of solder resist formation by improving the adhesive strength by completely photopolymerizing by irradiation A method for manufacturing a wiring board can be provided.
[0038]
Although the electrostatic spray coater method has been described as an example of the solder resist coating method in the present embodiment, the same effect can be obtained by other methods such as a curtain coater and a roll coater method.
[0039]
【The invention's effect】
As described above, according to the present invention, the solder resist applied to the end face of the printed wiring board is shielded by the exposure film having the light shielding portion of the area of 0.1 mm or more inside and 0.5 mm or more outside from the end face of the printed wiring board. However, this part is completely removed in the next development process by not irradiating ultraviolet rays at all , considering misalignment between the printed wiring board and the exposure film, and irregularly reflected outside the printed wiring board. Even if scattered, the solder resist on the end face is not irradiated with the ultraviolet ray 1.
[0040]
This structure prevents the phenomenon that a semi-exposed solder resist is generated in the development process of forming the solder resist, and this adheres to the transport conveyor and the liquid draining roll of the development equipment and then reattaches to other printed wiring boards. Thus, it is possible to realize a method for manufacturing a printed wiring board with improved soldering reliability during component mounting.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a method for manufacturing a printed wiring board in an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a method for manufacturing a printed wiring board in another embodiment of the present invention. Sectional view showing the method for manufacturing printed wiring boards [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ultraviolet 2 Acrylic board 3 Exposure film 4 Light-shielding part 5 Exposure table 6 Printed wiring board 7 Solder resist

Claims (1)

A step of applying solder resist ink to both sides and end surfaces of the printed wiring board by an electrostatic spray coater method, a step of drying the solder resist ink, and 0.1 mm or more on the inside and 0.1 mm on the outside from the end surface of the printed wiring board. Applying to the end face of the unexposed portion where the ultraviolet ray is not irradiated, the step of adhering the exposure film having a light-shielding portion of a region of 5 mm or more to the printed wiring board, the step of exposing the printed wiring board by ultraviolet irradiation through the exposure film A method for producing a printed wiring board comprising a step of developing and removing the solder resist that has been removed .

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