JPH06106096A - Electrostatic coating device - Google Patents

Abstract

PURPOSE:To enable the control of the coating pattern of the electrostatic coating device by disposing a coating pattern control electrode connected to a negative power source near to a spraying gun, etc. CONSTITUTION:The coating pattern control electrode 20 consists of a ring part 21 to be fixed to a cylindrical part 8a of a spraying gun 8, a leg part 22 extending diagonally downward from this ring part 21 and a bar-shaped electrode 23 mounted to the bottom end of the leg part 22. This bar-electrode 23 extends horizontally with the direction orthogonal with the transporting direction of a printed circuit board. As a result, the spread of the coating material particles ejected from the spraying gun 8 is arbitrarily adjustable in compliance with the shape of a work. The coating pattern in the transporting direction of the work is exactly controlled by moving also the coating pattern control electrode 20 back and forth integrally with the spraying gun 8 particularly when the spraying gun 8 moves back and forth in a transverse direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic coating apparatus for coating a surface of an object to be coated such as a printed circuit board with a photoresist or the like.

[0002]

2. Description of the Related Art The coating of a photoresist by an electrostatic coating method is more recent than that of a roll coater method or a screen printing method because a uniform coating can be formed and a through hole of a printed circuit board is not blocked by the photoresist. Is widely used in.

Such an electrostatic coating apparatus has a structure in which a spray gun is arranged in the upper part of the coating booth and a ground plate is arranged in the lower part, and a conveyor belt (paper belt) runs just above the ground plate. , By negatively charging the paint particles ejected from the spray gun, the paint particles are electrostatically attracted to the ground plate, and the paint is applied to the surface of the coated object that passes directly above the ground plate together with the conveyor belt. The particles are attached.

[0004]

In the above-mentioned conventional apparatus, since the paint particles ejected from the spray gun are negatively charged, they tend to repel each other and scatter in all directions. A ground plate is provided to suppress the scattering in all directions and to form a film efficiently.However, most of the paint particles ejected from the spray gun do not reach the surface of the object to be coated and the inner surface of the booth, etc. Adhere to.

[0005]

In order to solve the above problems, in the first invention of the present application, a coating pattern control electrode connected to a negative power source is arranged in the vicinity of a spray gun or the like, and in the second aspect of the present application. In the invention, the side plates are arranged on the front and rear side end portions of the ground plate and at positions along the traveling direction of the conveyor belt.

[0006]

By providing the coating pattern control electrode or the side plate, the spreading of the coating pattern in the traveling direction or the width direction can be suppressed.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a front view of an electrostatic coating apparatus according to the present invention, in which a box-shaped coating booth 1 is formed with an inlet 2 and an outlet 3 of a printed circuit board W which is an object to be coated. A paper belt 4 for conveyance is provided between the outlet 3 and the outlet 3. The paper belt 4 travels from an unwinding roll 5 equipped with a brake mechanism toward a winding roll 6 which is rotated by a motor, whereby the printed circuit board W is conveyed from an inlet 2 to an outlet 3.

A window 7 is provided in the coating booth 1, and a rotary cup type spray gun 8 is arranged at a position visible through the window 7. The spray gun 8 is attached to the lower end of a cylinder unit 10 that reciprocates along a rail 9 in the width direction orthogonal to the traveling direction of the paper belt 4, and in the vicinity of the nozzle of the spray gun 8, paint particles 11 ejected from the nozzle are provided. Is provided with an electrode for negatively charging, and an exhaust blower 12 is provided at the bottom of the coating booth 1.

Further, the electrostatic coating apparatus according to the present invention is connected to a negative power source, the coating pattern control electrode 20, the ground plate 30 which can be adapted to the size of the printed circuit board W, and the side plate which suppresses the excessive spreading of the coating pattern. 40 is provided.

First, the coating pattern control electrode 20 will be described with reference to FIGS. 2 to 6. 2 is a front view of the coating pattern control electrode, and FIG. 3 is a view taken in the direction of arrow A in FIG. The leg portion 22 extends obliquely downward from the ring portion 21, and the bar-shaped electrode 23 attached to the lower end of the leg portion 22. Bar-shaped electrode 2
The reference numeral 3 extends horizontally in a direction orthogonal to the conveyance direction of the printed circuit board W. A protrusion may be formed on the lower surface of the electrode to facilitate discharge from the electrode 23.

FIG. 4 is a front view of a coating pattern control electrode according to another embodiment, FIG. 5 is a view in the direction of arrow B in FIG. 4, and FIG. 6 is a plan view of a coating pattern control electrode according to another embodiment. In the embodiment shown in FIGS. 4 and 5, the bar-shaped electrode 23 is provided in the vertical direction and the tip is sharpened.
In the embodiment shown in FIG. 2, four bar-shaped electrodes 23 are extended in the direction of conveyance of the printed circuit board W and two in the direction orthogonal to the direction of conveyance of the circuit board W, and coating patterns are shown by imaginary lines in the figure. Thus, the shape is close to the shape of the printed circuit board W.

On the other hand, the ground plates 30 are a central ground plate 32 fixed to the frame 31 in the coating booth 1 and three outer ground plates provided on both sides of the central ground plate 32 along the running direction of the paper belt 4. The outer ground plates 33, 34, 35 are composed of the plates 33, 34, 35.
Cylinder unit 3 standing on a bracket extending from 1
6, 37, and 38 are attached to the tip ends of the rods, and are configured to move up and down independently by the operation of each cylinder unit.

The central ground plate 32, the outer ground plates 33, 34, 35 and the outer guide 39 for preventing the side edges of the paper belt 4 from sagging when the cylinder units are fully extended are flush with each other. There is. Further, an inner guide 50 fixed to the frame 31 is provided in front of and behind the central ground plate 32.

Partition plates 51 and 52 are provided between the outer ground plates 33 and 34 and between the outer ground plates 34 and 35. These partition plates 51 and 52 are stainless steel plates,
It is made of an insulating material such as Teflon resin, and its height is set to be substantially equal to that of the central ground plate 31.

By dividing the ground plate 30 into the central ground plate 32 and the outer ground plates 33, 34 and 35 in this manner, when the width of the printed circuit board W is small, all the cylinder units 36, 37 and 38 are compressed. Outer ground plate 33,
34, 35 are lowered so that only the central ground plate 32 acts as a ground plate, and as the width of the printed circuit board W increases, the cylinder units 36, 37, 3
8 is sequentially expanded to raise a predetermined outer ground plate, and the width of the ground plate is adjusted to the width of the printed circuit board W.

By the way, one of the outer ground plates 33,
Even when lowering 34 and 35, since the partition plates 51 and 52 remain, the traveling paper belt 4 does not hang down and come off from the outer guide 39.

On the other hand, the side plate 40 is the ground plate 30.
Are arranged along the traveling direction of the conveyor belt 4 on the front and rear side ends thereof, and can be moved back and forth in the direction orthogonal to the traveling direction of the conveyor belt 4 by the operation of the cylinder unit 41. This side plate 40 is for suppressing the excessive spread of the coating pattern. Therefore, as shown in FIG. 9, when only the central ground plate 32 and the outer ground plate 33 act as ground plates, the cylinder unit By driving 41, the side plate 40 is advanced further to the center position than the position shown in the figure, that is, near the outer end position of the outer ground plate 33.

In the above, the negatively charged paint particles 11 ... Are ejected from the spray gun 8, and the paint particles 11 ... Are electrostatically focused toward the earth plate 14 and placed on the paper belt 4 to enter. The coating particles 11 are attached to the surface of the printed circuit board W, which is the object to be coated, which is directed from 2 to the outlet 3. At this time, the negatively charged paint particles 11 ... Are repelled by the coating pattern control electrode 20 in the upper part and squeezed, and the side plate 40 in the lower part.
Spreading is suppressed by and is efficiently applied to the surface of the printed circuit board W.

[0019]

As described above, according to the first invention of the present application, since the coating pattern control electrode connected to the negative power source is arranged near the spray gun or the like, the spread of the paint particles ejected from the spray gun. Can be arbitrarily adjusted according to the shape of the object to be coated. In particular, when the spray gun reciprocates in the width direction, the coating pattern control electrode can be accurately reciprocated by reciprocating the coating pattern control electrode integrally with the spray gun.

According to the second invention of the present application, since the side plates are arranged on the front and rear side end portions of the earth plate and along the traveling direction of the conveyor belt, the excessive spread of the paint particles in the width direction is prevented. Since the side plate can be moved back and forth in the width direction (direction orthogonal to the traveling direction of the conveyor belt), it is possible to effectively suppress the excessive spread of the paint particles according to the size of the object to be coated.

[Brief description of drawings]

FIG. 1 is a front view of an electrostatic coating device according to the present invention.

FIG. 2 is a front view of a coating pattern control electrode.

3 is a view in the direction of arrow A in FIG.

FIG. 4 is a front view of a coating pattern control electrode according to another embodiment.

5 is a view in the direction of arrow B in FIG.

FIG. 6 is a plan view of a coating pattern control electrode according to another embodiment.

FIG. 7 is a plan view of the ground plate and the third plate.

8 is a view in the direction of arrow C in FIG.

9 is a view in the direction of arrow D in FIG.

[Explanation of symbols]

1 ... Painting booth, 4 ... Conveyor belt, 8 ... Spray gun,
11 ... Paint particles, 20 ... Coating pattern control electrode, 30 ...
Ground plate, 40 ... Side plate, W ... Printed circuit board which is the object to be coated.

Claims (4)

[Claims] 1. An object to be coated is placed on a conveyor belt that travels in a coating booth, the paint particles ejected from a spray gun disposed above the conveyor belt are negatively charged, and the negatively charged paint particles are conveyed. In an electrostatic coating device that is moved in the air toward the ground plate directly below the belt to adhere to the surface of the object to be coated, this electrostatic coating device is equipped with a coating pattern control electrode connected to a negative power source. Characteristic electrostatic coating device. 2. The spray gun is capable of reciprocating in a direction orthogonal to the traveling direction of the conveyor belt, and the coating pattern control electrode is also capable of reciprocating integrally with the spray gun. Item 1. The electrostatic coating device according to Item 1. 3. An object to be coated is placed on a conveyor belt running in a coating booth, the paint particles ejected from a spray gun arranged above the conveyor belt are negatively charged, and the negatively charged paint particles are conveyed. In an electrostatic coating device in which the air is moved toward the ground plate directly below the belt so that it adheres to the surface of the object to be coated, the front and rear side edges of the ground plate are applied along the running direction of the conveyor belt. An electrostatic coating device in which a side plate that suppresses the spread of the pattern is arranged. 4. The electrostatic coating apparatus according to claim 3, wherein the side plate is movable back and forth in a direction orthogonal to the traveling direction of the conveyor belt.