JP2000013003A - Manufacture of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of soldering at the time of mounting parts without generating solder resist in a semi-exposed state by preventing solder resist ink applied to the end face of a printed wiring board from being irradiated with ultraviolet rays at the time of exposure. SOLUTION: Solder resist 7 in a part to which ultraviolet rays 1 are applied through an exposure film 3 is photopolymerized and it is not dissolved in a next developing process. On the other hand, solder resist in a non-exposed part with which the ultraviolet rays 1 are not irradiated is completely dissolved and removed in a next developing process and a prescribed pattern is obtained. The exposure film 3 of a part corresponding to a position at the end face of the printed wiring board 6 can cut the ultraviolet rays 1 by installing a light shielding part 4, and solder resist 7 applied to the end face is not irradiated with the ultraviolet rays 1. Thus, solder resist in a semi-exposed state is not generated in the developing process of the formation of solder resist, and the reliability of soldering at the time of mounting the parts can be improved.

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, a mobile communication telephone, and a video camera.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become higher in function and higher in density, electronic components have tended to become smaller, more highly integrated, and faster.

[0003] For this reason, the form of the printed wiring board has been increasingly reduced in dielectric constant, thinner and lighter, and the wiring density has been increased, and the solder resist covering this wiring pattern has a fine line covering property. There has been a demand for improved uniformity as well as soldering reliability of component mounting parts.

Hereinafter, a conventional method for manufacturing a printed wiring board will be described. A circuit pattern is formed on the metal layers on the front and back surfaces of the base material by means such as etching. next,
An ultraviolet curing solder resist ink is applied to the printed wiring board on which the circuit pattern is formed. As a coating method here, first, positive or negative charges are charged on the entire surface of the printed wiring board via a transport jig or the like.

On the other hand, the solder resist ink is charged with a charge opposite to the charge on 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 discharging the solder resist ink from the tip of the spray nozzle to the surface of the printed wiring board.

At this time, the solder resist ink is generated along the line of electric force generated between the electric charge charged in the solder resist ink and the opposite electric charge charged in the printed wiring board, in addition to the discharge force of the spray. It can be applied to a printed wiring board by electrostatic attraction. Thereafter, a solder resist ink is applied to the opposite surface of the printed wiring board. The solder resist ink applied to both sides of the printed wiring board in this way is temporarily cured by, for example, drying at 80 ° C. for about 20 minutes.

[0007] Then, a necessary portion is selectively photopolymerized and exposed in an exposure step by ultraviolet irradiation through a negative pattern exposure film. At this time, the exposed portion is dissolved in a subsequent developing step using an aqueous solution of sodium carbonate or the like, and the exposed portion remains on the substrate surface without being dissolved.

Finally, the solder resist is thermally cured by, for example, a heat treatment at 150 ° C. for about one hour to complete the formation of the solder resist. Thereafter, if necessary, parts drawing printing, gold plating, external processing, etc. are performed to complete the printed wiring board.

In the above description, the exposure step will be described in more detail below with reference to the drawings.

FIG. 3 is a sectional view showing a conventional method for manufacturing a printed wiring board. In FIG. 3, reference numeral 11 denotes ultraviolet light, 12 denotes an acrylic plate, 13 denotes an exposure film, 14 denotes an exposure table, 15 denotes a printed wiring board, and 16 denotes a solder resist.

A method for manufacturing a printed wiring board having the above-described configuration will be described. Solder resist 16 on the surface
The printed wiring board 15 coated and dried is positioned 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 acrylic plate 12 holding the printed wiring board 15 and the exposure table 1
4 to make the printed wiring board 15
And the exposure film 13 to improve the adhesion. Thereafter, ultraviolet rays 11 are irradiated perpendicularly to the solder resist 16 on the surface of the printed wiring board 15 from the side of the acrylic plate 12. Exposure is performed on the opposite surface in the same manner as described above.

Here, the exposure film 13 is constituted by a light-shielding portion and a non-light-shielding portion in accordance with the pattern shape of the pattern in which the solder resist 16 is to be finally left. The part 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 developing step. Conversely, the unexposed part of the solder resist 16 not irradiated with the ultraviolet rays 11 is Is completely dissolved and removed in the developing step to obtain a predetermined pattern.

[0013]

However, in the above-mentioned conventional method for manufacturing a printed wiring board, when a solder resist ink is applied to the surface of the printed wiring board, the end face which is a cut surface around the printed wiring board is also applied. The solder resist ink will be applied. When exposing the periphery of the printed wiring board in the exposing step, the solder resist ink applied to the end face is simultaneously irradiated with ultraviolet rays to be exposed.

Since the ultraviolet rays applied here are perpendicularly incident on the surface of the printed wiring board, they are not directly applied to the solder resist on the end face of the printed wiring board. However, it is indirectly performed by the scattered light. Therefore, the exposed state of the end face is very unstable and becomes a semi-exposed and semi-polymerized state, and in the subsequent development process, the solder resist on the end face is not dissolved because it is in a semi-exposed state, but the adhesive strength is weak and easily peeled off. Become.

As a result, when the printed wiring board is transported in the developing step, the semi-polymerized solder resist peeled from the end face is transported by a transport conveyor or a draining roll unit provided in each of the developing, washing and drying facilities. This has been a problem that this adheres again to the soldered portion of the circuit pattern on the surface of the printed wiring board that has been transported later, resulting in poor soldering when mounting various chip components.

Further, when the semi-exposed solder resist is mixed into the developing solution in the developing booth, it is not dissolved by the developing solution, so that it is accumulated as foreign matter in the developing solution. There is a problem in that it also causes deterioration of the developer and contamination of the developing equipment.

The present invention solves the above-mentioned conventional problems, and does not generate a solder resist in a semi-exposed state in a developing step of forming a solder resist, thereby improving the soldering reliability at the time of component mounting. It is an object of the present invention to provide a method for producing the same.

[0018]

According to the present invention, there is provided a printed wiring board comprising: a step of applying a solder resist ink to the printed wiring board; a step of drying the solder resist ink; Manufacturing of a printed wiring board, comprising: an exposure step of photopolymerizing a solder resist ink by irradiating a necessary portion with ultraviolet rays through a substrate; and a step of removing unnecessary solder resist ink not irradiated with the ultraviolet rays by development. The method is characterized in that the solder resist ink applied to the end face of the printed wiring board is not irradiated with ultraviolet rays at the time of exposure.

According to the present invention, there is provided a method of manufacturing a printed wiring board in which a solder resist in a semi-exposed state is not generated in a development step of forming a solder resist and soldering reliability at the time of component mounting is improved.

[0020]

DETAILED DESCRIPTION OF THE INVENTION The invention described in claim 1 of the present invention provides a step of applying a solder resist ink to a printed wiring board, a step of drying the solder resist ink, and the steps of: In a method for manufacturing a printed wiring board, a method for manufacturing a printed wiring board, comprising: an exposure step of photopolymerizing a solder resist ink by irradiating a part with ultraviolet light; and a step of removing unnecessary solder resist ink not irradiated with ultraviolet light by development. The solder resist ink applied to the end face of the board is a method for manufacturing a printed wiring board, which is characterized by not irradiating ultraviolet rays at the time of exposure. Because it is not irradiated with ultraviolet rays and is not photopolymerized, it can be completely dissolved and removed in the developing process, Without adhering semi exposure state Bei conveyor and draining roll, an effect that can form a solder resist in a necessary portion of the printed wiring board surface.

According to a second aspect of the present invention, the outer peripheral portion of the printed wiring board is irradiated with ultraviolet rays by providing a light-shielding portion on an exposure negative film used in the exposure step at a portion corresponding to the outer peripheral portion of the printed wiring board. According to this method, the outer peripheral portion of the printed wiring board can be shielded from ultraviolet rays by a film used at the time of exposure, and the solder resist on the end face is irradiated with ultraviolet rays. Since it is not performed, it is possible to completely dissolve and remove it in the developing step, and at the same time, it has an effect that a solder resist can be formed in a necessary portion without affecting an internal product portion other than the outer peripheral portion of the printed wiring board.

According to a third aspect of the present invention, there is provided a printed wiring board having an area not less than 0.5 mm outward from the outer peripheral end and 0.1 mm inward from the end face of the printed wiring board.
The method for manufacturing a printed wiring board according to claim 2, wherein the end surface of the printed wiring board is not irradiated with ultraviolet light by shielding the above-mentioned region from light, and the end portion of the printed wiring board is at least inward from the end surface. Since the area of 0.1 mm is shielded from light on the exposure film, the end face is not irradiated with ultraviolet rays even if the amount of misalignment at the time of exposure between the exposure film and the printed wiring board is taken into consideration. At least 0.5 mm of the area outward from the end face is shielded from light on the exposure film, and the part exposed to the outside of the end face is not irradiated with ultraviolet light within a distance of 0.5 mm therefrom. There is no need to worry about irradiation, and it has the effect that it can be completely dissolved and removed in the developing step.

According to a fourth aspect of the present invention, there is provided a step of applying a solder resist ink to a printed wiring board, a step of drying the solder resist ink, and irradiating a required portion with ultraviolet rays through a film. In a method of manufacturing a printed wiring board, the method includes a step of removing unnecessary solder resist ink that has not been irradiated with ultraviolet rays by development, and an exposure step of photopolymerizing the solder resist ink. A method of manufacturing a printed wiring board, comprising irradiating ultraviolet light to a solder resist ink from an oblique direction of the surface of the printed wiring board during exposure. With this configuration, the solder on the end face of the printed wiring board is provided. The resist is directly illuminated by the amount of the vertical component caused by the angle of the ultraviolet light applied to it Therefore, it can be completely photopolymerized, does not dissolve in the development process, can maintain sufficient adhesive strength, and adheres to the transport conveyor or liquid removal roller of the development equipment in a semi-exposed state. Has the effect of disappearing.

The invention according to claim 5 is obtained by bonding a metal foil to both surfaces of a compressible porous substrate made of an aromatic polyamide impregnated with an epoxy resin, heating and pressing, and then forming a circuit pattern. 5. A method for manufacturing a printed wiring board according to claim 1, wherein the aromatic polyamide impregnated with an epoxy resin is cut around the printed wiring board. In the conventional solder resist formation, it has been difficult to prevent the solder resist on the end face from peeling off at the same time as the cutting debris because the surface is brittle and cutting debris is generated.
Alternatively, it is possible to completely eliminate the peeling-off phenomenon by completely removing the solder resist on the end face by the developing process according to 2 or 3 or by completely photopolymerizing the solder resist according to claim 4. Has an action.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 are cross-sectional views illustrating a method for manufacturing a printed wiring board according to an embodiment of the present invention. In FIG. 1, by shielding the exposed film corresponding to the end face of the printed wiring board from light, the solder resist on the end face can be completely removed in the next exposure step.
In the above, the solder resist on the end face of the printed wiring board is completely irradiated with ultraviolet rays, and has an effect that photopolymerization can be sufficiently performed.

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.

The operation of the method for manufacturing a printed wiring board configured as described above will be described below.

An ultraviolet-curable solder resist ink is applied to a printed wiring board on which a circuit pattern has been formed on the front and back metal layers of the base material by means such as etching.
As an application method here, an electrostatic spray coater method will be described as an example.

First, positive or negative charges are charged on the entire surface of the printed wiring board 6 via a transport jig or the like. On the other hand, the solder resist ink is charged with a charge opposite to the charge on the printed wiring board via a spray nozzle or the like. Then, the solder resist ink is applied to the entire surface of the printed wiring board by discharging the solder resist ink from the tip of the spray nozzle to the surface of the printed wiring board.

At this time, in addition to the spraying force of the solder resist ink, the solder resist ink follows the electric force lines generated between the electric charge charged on the solder resist ink and the opposite electric charge charged on the printed wiring board 6. It can be applied to the printed wiring board 6 by the generated electrostatic attraction. Thereafter, a solder resist ink is applied to the opposite surface of the printed wiring board 6 in the same manner. The solder resist ink applied to both sides of the printed wiring board 6 in this manner is then, for example,
Temporarily cured by drying for about a minute.

Then, a necessary portion is selectively photopolymerized and exposed in an exposure step by ultraviolet irradiation through a negative pattern exposure film. 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 bonded to the acrylic plate 2 in advance.

Next, the adhesion between the printed wiring board 6 and the exposure film 3 is increased by evacuating the space between the acrylic board 2 holding the printed wiring board 6 and the exposure table 5. Thereafter, ultraviolet rays 1 are irradiated perpendicularly to the solder resist 7 on the surface of the printed wiring board 6 from the side of the acrylic plate 2. Exposure is performed on the opposite surface in the same manner as described above.

Here, the exposure film 3 is made of a solder resist 7
Is constituted by a light-shielding portion and a non-light-shielding portion in accordance with the pattern shape of the picture to be finally left. The part 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 developing step. Conversely, the unexposed part of the solder resist 7 not irradiated with the ultraviolet light 1 is Is completely dissolved and removed in the developing step to obtain a predetermined pattern. As shown in the figure, the exposed film 3 in the portion corresponding to the position of the end surface of the printed wiring board 6 can block the ultraviolet light 1 by providing the light shielding portion 4 as shown in the figure, and the ultraviolet light 1 is not irradiated to the solder resist 7 applied to the end surface.

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 light 1 is not affected even when the misalignment between the printed wiring board 6 and the exposure film 3 is considered. It is not irradiated to the end face of the printed wiring board 6. Further, the light-shielding portion 4 is provided at least 0.5 mm, preferably 1.0 mm or more outward from the end surface of the printed wiring board 6, so that the ultraviolet rays scattered and reflected irregularly outside the printed wiring board 6 are taken into consideration. The ultraviolet light 1 is not irradiated on the solder resist 7 in the portion exposed on the end face.

In FIG. 2, the ultraviolet light 1 is applied to the end face of the printed wiring board 6 from obliquely above, whereby the vertical component of the ultraviolet light 1 is directly applied to the solder resist 7 on the end face according to the angle. Is photopolymerized. Thereafter, in the next developing step, the unexposed portions are dissolved in a developing step using an aqueous solution of sodium carbonate or the like, and the exposed portions remain on the substrate surface without being dissolved. Finally, the solder resist is heat-cured by, for example, a heat treatment at 150 ° C. for about one hour to complete the formation of the solder resist. After that, if necessary, parts drawing printing, gold plating, outer shape processing, etc. are performed, and the printed wiring board 1 is completed.

As described above, according to the present embodiment, the solder resist 7 applied to the end surface of the printed wiring board 6 is completely removed in the next development step by not irradiating the ultraviolet light 1 at all, or is sufficiently removed. By irradiating the ultraviolet light 1 to complete the photopolymerization to improve the adhesive strength,
It is possible to provide a method for manufacturing a printed wiring board in which a solder resist in a semi-exposed state is not generated in a development process of forming a solder resist, and soldering reliability at the time of component mounting is improved.

In the present embodiment, an electrostatic spray coater method has been described as an example of a method of applying a solder resist. However, similar effects can be obtained by other methods, for example, a curtain coater or a roll coater method.

[0038]

As described above, according to the present invention, the solder resist applied to the end surface of the printed wiring board is completely removed in the next developing step by not irradiating the ultraviolet ray at all.
Alternatively, by fully irradiating ultraviolet rays and performing complete photopolymerization to improve the adhesion, a semi-exposed solder resist is generated in the development process of solder resist formation, and this is formed on a transport conveyor or a draining roll of a development facility. It is possible to realize a method of manufacturing a printed wiring board in which the phenomenon of re-adhering to another printed wiring board after being attached is prevented, and the soldering reliability during component mounting is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a method for manufacturing a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a method of manufacturing a printed wiring board according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional method for manufacturing a printed wiring board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultraviolet light 2 Acrylic board 3 Exposure film 4 Light shielding part 5 Exposure table 6 Printed wiring board 7 Solder resist

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Yoshida, Inventor 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Takahiro Nishino 1006 Kadoma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial F Terms (reference) 2H096 AA26 BA01 CA12 CA20 EA02 EA30 GA08 HA01 5E314 AA27 DD07 EE09 FF01 GG26

Claims (5)

[Claims] 1. A step of applying a solder resist ink to a printed wiring board, a step of drying the solder resist ink, and a step of photopolymerizing the solder resist ink by irradiating a required portion with ultraviolet rays through a film. In the method of manufacturing a printed wiring board, comprising: an exposure step to be performed, and a step of removing unnecessary solder resist ink that has not been irradiated with ultraviolet rays by development, with respect to the solder resist ink applied to the end surface of the printed wiring board.
A method for manufacturing a printed wiring board, comprising not irradiating ultraviolet light during exposure. 2. The printing method according to claim 1, wherein the outer peripheral portion of the printed wiring board is not irradiated with ultraviolet rays by providing a light-shielding portion on an exposure negative film used in the exposure step at a portion corresponding to the outer peripheral portion of the printed wiring board. Manufacturing method of wiring board. 3. The printed wiring board is shielded from light by shielding an area of 0.5 mm or more outward from an outer peripheral end of the printed wiring board and an area of 0.1 mm or more inward from an end face of the printed wiring board. 3. The method for manufacturing a printed wiring board according to claim 2, wherein the end face is not irradiated with ultraviolet rays. 4. A step of applying a solder resist ink to a printed wiring board, a step of drying the solder resist ink, and a step of photopolymerizing the solder resist ink by irradiating a necessary portion with ultraviolet rays through a film. In the method of manufacturing a printed wiring board, comprising: an exposure step to be performed, and a step of removing unnecessary solder resist ink that has not been irradiated with ultraviolet rays by development, with respect to the solder resist ink applied to the end surface of the printed wiring board.
A method for manufacturing a printed wiring board, comprising irradiating ultraviolet light from an oblique direction on the surface of the printed wiring board during exposure. 5. A printed wiring board obtained by laminating a metal foil on both surfaces of a compressible porous substrate made of an aromatic polyamide impregnated with an epoxy resin, heating and pressing, and then forming a circuit pattern. A method for manufacturing a printed wiring board according to claim 1.