JPS6232691A - Masking processing of printed wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for soldering electronic components to required locations on a printed wiring board on which an electrical wiring circuit is printed. The present invention relates to a method of masking a printed wiring board to cover parts that do not require soldering to prevent soldering, and an apparatus therefor.

[Conventional technology]

A photopolymerizable resin composition (hereinafter referred to as resist ink) is used for masking printed wiring boards. This resist ink is applied to the entire surface of the printed wiring board using a screen printing method, and then the areas that require masking are irradiated with light (ultraviolet light, etc.) to harden the resist ink. Masking is performed by washing off the resist ink in the areas that are not irradiated, that is, the resist ink in an uncured state, with an organic solvent or the like.

Resist inks are generally formulated with resins based on epoxy acrylates and their derivatives, photopolymerization initiators such as benzoin and anthracene, and viscosity modifiers such as acrylic monomers and organic solvents. Commercially available products are used.

Printed wiring boards are mainly made of thermosetting resin such as phenolic resin or glass epoxy resin, and a wiring circuit is formed using copper as a conductor and solder plating.
Many of them have steps on the order of micrometers, and screen printing was mainly used because it was necessary to uniformly coat the masking agent.

However, the screen printing method has the disadvantage that it requires processes such as overprinting in order to obtain a thick coating film of 30 μm or more, which makes workability and mass production difficult.

A possible solution to this problem is to apply a film using a coating roller, but with current roll coaters it is difficult to achieve a film thickness of 10 μm or more, and
The penetration of the masking agent between the wiring circuits is also very poor, making it impossible to obtain a high degree of masking effect.

Considering this point, in order to have a coating roller rub a printed wiring board, which is a discontinuous single board, it is necessary to push the printed wiring board out in the same direction as the rotation direction of the coating roller circumferential surface, and then transport it by the coating roller. It is said that it is convenient for the feeding and unloading operations in the coating process to pass through the material in a way that it is pushed out.
After further investigation, the present invention was completed.

[Problem that the invention seeks to solve]

In order to transfer the resist ink by protruding the printed wiring board in the direction of rotation of the coating roller, all of the resist ink on the circumferential surface of the coating roller is transferred to the printed wiring board when it rotates away from the printed wiring board. The resist ink must be carefully prepared so that it does not remain on the surrounding surface.

However, in order to uniformly apply resist ink to the circumferential surface of the coating roller, it is necessary to apply a thin film, and as a result, the film transferred and formed on the printed wiring board is also thin, making it difficult to apply printed wiring for industrial equipment. The coating properties between circuits are particularly poor for substrates that have conductor steps, and
In addition, when the resist ink rotates and separates from the printed wiring board, it causes a stringing phenomenon between the printed wiring board and the coating roller, which causes the coating to look like ripples on the coating surface of the printed wiring board. It was not possible to form a thick, uniform and smooth resist ink coating on the surface of the printed wiring board due to the formation of fine film spots (coating film steps).

Therefore, the present invention aims to mask a printed wiring board with a smooth and thick (uniform) coating of resist ink, and for this purpose, provides a method and apparatus for applying a high viscosity resist ink using a coating roller for masking processing. That is.

[Means for solving problems]

In the masking process using a conventional coating roller, the present invention is capable of coating a substrate regardless of the viscosity of the resist ink when the substrate is gripped and pushed out in the opposite direction of the rotation direction of the coating roller circumferential surface to forcibly rub the coating roller circumferential surface. This method was completed based on the knowledge that the resist ink on the circumferential surface of the roller adheres to the printed wiring board, creating a beautiful masking coating.

That is, in the printed wiring board masking method according to the present invention, when applying resist ink to the surface of a printed wiring board using a coating roller and performing masking processing, the printed wiring board is ejected in the opposite direction to the rotational direction of the coating roller circumferential surface. The method is characterized in that the resist ink on the circumferential surface of the coating roller is applied by rubbing the circumferential surface of the coating roller onto the printed wiring board.

The material around the coating roller is isoprene rubber,
All commonly used rubbers such as chloroprene rubber, silicone rubber, urethane rubber, fluorine rubber, butyl rubber, and soft polyvinyl chloride can be used, but preferably butyl rubber with a hardness of 5 to 30° is the best in terms of coating performance. In good condition.

Hereinafter, the first example will be explained with reference to the drawings.
In the embodiment illustrated in FIGS.
is set within the fixed frame 13 of the table 12.

The coating roller 14 is attached to a trolley 15,
The first
It is driven straight from the left side to the right side in FIGS. The rails of the trolley ■5 are slightly higher on the outside of the left and right fixed frames 13a and 13b, and the coating roller 14 contacts the printed wiring board 11 between the fixed frames 13a and 13b.
On the left and right outer sides of the fixed frames 13a and 13b, the cart runs on a high portion of the rail, so that the coating roller is lifted upward and separated from the printed wiring board 11.

- In FIG. 1, a doctor roll 16 is acting on the coating roller 14, and this is a doctor knife I7 as shown in FIG. 2, or a doctor knife 18 rotating in the opposite direction to the coating roller 14 as shown in FIG. It is also possible to replace the roll 19 with a coating, thereby making the coating film of the resist ink 20 uniform.

When coating both the front and back surfaces of the printed wiring board 11, coating rollers 14a and 14b with different rotation directions are placed vertically facing each other as shown in FIG.

Several pairs of upper and lower conveyor pieces 2 which actively rotate while holding both the left and right edges of the printed wiring board 11 on both the feed side and the take-out side
1.22.23.24, 3T, and 32.33.34 are provided, and the feeding piece 21.22.23.24 feeds in, and the taking out piece 31.32.33.34 pulls out. These feed pieces 21, 22, . . . . . . and take-out pieces 31, 32, . attached to the frame of the coating equipment,
It can be set at a required position according to the width of the printed wiring board 11.

FIG. 5 shows an embodiment in which coating is applied only to one side using the coating apparatus shown in FIG. They may also be rotated in the same direction.

Of course, the equipment is a little complicated, but in these embodiments, the rear end of the printed wiring board 11 is fed with a push rod so as to protrude, the coating roller 14 is rubbed, and the tip of the printed wiring board 11 that protrudes is grasped. You can also grab it with a stick and pull it out.

〔Effect of the invention〕

According to the present invention, the printed wiring board 11 rubs against the coating roller circumferential surface 14, and since the direction of movement thereof is opposite to the rotating direction of the coating roller circumferential surface 14, the doctor 16, 17, 19... The resist ink 20 coated on the circumferential surface of the coating roller is scraped off and applied to the printed wiring board 11, and then the coating roller 1 rotates away from the printed wiring board 11.
Since no resist ink remains on the circumferential surface of 4, no stringing phenomenon occurs.On the other hand, the resist ink 20 is applied to the printed wiring board Fill by being rubbed by the coating roller 14. It is not necessary to adjust the viscosity of the resist ink 20, and it is possible to apply a thick film of the resist ink 20 with high viscosity and concentration to the printed wiring board 11 for masking processing. Since no drag phenomenon occurs, the resist ink coated on the printed wiring board 11 adheres neatly to the printed wiring board without any fine bubbles getting into the coating film, and also, the coating film of the resist ink applied to the printed wiring board 11 adheres to the printed wiring board neatly. While rubbing the printed wiring board 11, the fixed frame 13 and the feed/take-out pieces 21, 22, 23.
24, 31, 32, 33, 34, etc., so that it is not pushed back by the coating roller, and the masking process is uniformly performed without proper coating film steps or spots. For example, the conveyance speed of printed wiring boards,
The film thickness can be freely controlled from 20 μm to 200 μm by changing the material and surface hardness of the coating roller circumferential surface, and as is clear, the present invention has many advantages.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 3, FIG. 4, and FIG. 5 are respectively sectional side views of essential parts of a masking processing apparatus used for carrying out the present invention. 11...Printed wiring board, 12...Table, 1
3...Fixed frame, 14...Coating roller, 15...Dolly, 16.17.18.1
9...Doctor, 20...Resist ink, 21.
22.23.24...Send piece, 31.32.33.
34... Take-out frame, 40... Conveyance roller. Applicant Technolol Co., Ltd. Company Asahi Chemical Research Institute Co., Ltd.

Claims (1)

[Claims] When applying a photopolymerizable resin composition to the surface of a printed wiring board using a coating roller and performing masking treatment, the printed wiring board is pushed out in the opposite direction to the rotational direction of the coating roller's circumferential surface and rubbed against the coating roller's circumferential surface, thereby coating the surface of the printed wiring board. A method for masking a printed wiring board, which comprises applying a photopolymerizable resin composition on the peripheral surface of a roller by rubbing it onto the printed wiring board.