JP2670027B2 - Electrostatic coating method for resist coating material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electrostatically coating a coating material such as a solder resist on a flat substrate such as a printed circuit board.

[0002]

2. Description of the Related Art As a method of coating a coating material such as a solder resist on a flat object to be coated such as a printed circuit board,
There are a method of screen printing, a method of reciprocating an air or airless coating machine, and a method of coating while coating an object with a conveyor.

However, although these conventional methods can obtain a relatively uniform film thickness distribution, the coating efficiency is insufficient, and when a water-based solder resist coating material is applied, There is a problem that the bubbles are involved and the bubbles are included in the coating film.

Further, although an air atomizing electrostatic coating apparatus and an airless atomizing electrostatic coating apparatus to which static electricity is added have been proposed, the above-mentioned problems have not been fundamentally solved.

Next, a method of reciprocating a rotary atomization type electrostatic coating machine to coat an object to be coated while conveying it by a conveyor, and a method of using a bell type electrostatic coating machine is also known. However, with this method, it is difficult to obtain a uniform film thickness distribution because the spray pattern is hollow and large. It has been proposed to correct these spray patterns with shaping air, etc.
Problems such as a decrease in coating efficiency occur.

Further, in the case of applying the disk type electrostatic coating machine, since the article to be coated is conveyed on the circumference around the coating machine, the coating efficiency is high, but the size of the plate-like article to be coated is large. Therefore, there is a problem that the film thickness is not uniform, and when the coating is performed while rotating for double-sided coating, the edge portion is thickened.

[0007]

According to the present invention, there is provided the above-mentioned object of an electrostatic coating method of a resist coating composition, which comprises electrostatically coating a resist coating composition on a flat substrate for a printed circuit board. The relation between L and R satisfies L ≧ 2R, where R is the distance from the rotary atomizing head of the coating and L is the length of the straight line portion of the flat coating, and the flat coating is The present invention provides a method for electrostatically coating a resist coating composition, which comprises applying a resist coating material atomized by a rotary fog head to an object to be coated with an interval of 50 mm or less by electrostatic force. .

[0008]

1 and 2, a method for electrostatically coating a resist coating material according to a preferred embodiment of the present invention, and an electrostatic coating for a plate-shaped article for carrying out the method. An example of the device will be described.

This electrostatic coating apparatus is capable of coating both sides of the article to be coated with one coating apparatus, and includes a loop conveyor apparatus 12 for conveying the flat article 10 to be coated, a reversing apparatus 14, and An atomizing device 18 having a rotary atomizing head 16 (FIG. 2), a supporting device 20 for supporting the atomizing device 18, and a coating booth 22 are provided.

The loop conveyor device 12 includes a chain 24 driven along a predetermined loop orbit, and a chain 24.
A plurality of hangers 26 connected at a constant pitch to
A drive device (not shown) for driving the chain 24 at a constant speed along a predetermined track.

The hanger 26 comprises a plurality of flat plate-shaped articles 1 to be coated.
0 is suspended at a constant pitch. In order to make the coating film uniform, the distance d between the flat plate-shaped objects 10 is
It is preferably 50 mm or less.

The loop conveyor device 10 includes a mounting portion A
, A first linear portion B, an inverted portion C, a second linear portion D, and a detached portion E.

At the mounting portion A, the flat article 10 is successively hung from the hanger 26.

A first straight line portion B and a second straight line portion D
Have opposite transport directions, are parallel, have a length L, and have a spacing of 2R. The above L and R are L ≧ 2 because the front and back surfaces of the flat article 10 are uniformly coated.
It is necessary to have an R relationship.

At the reversing portion C, a reversing device 14 as described below is arranged, and the flat plate-shaped article 10 is reversed by 180 °.

At the removed portion E, the coated flat article 10 is removed.

In the embodiment shown in FIG. 1, the mounting portion A and the removal portion E are composed of first and second straight portions B and D.
The first and second straight portions B and D and the mounting portion A and the detaching portion E are arranged adjacent to each other with a distance therebetween, and various pretreatments or post-treatments are performed between them. An apparatus for performing processing or the like can be provided.

The reversing device 14 reverses the flat object 10 suspended on the hanger 26. As a result, one surface of the flat article 10 is coated on the first straight line portion B, and the opposite surface is coated on the second straight line portion D.

The atomizing device 18 has a rotary atomizing head 16, and the rotation axis of the rotary atomizing head 16 extends in the vertical direction. The rotary atomizing head 16 atomizes the coating material and sprays it radially. As the rotary atomizing head 16, a disk type head, a bell type head or the like can be used. A static voltage is applied between the rotary atomizing head 16 and the flat plate-shaped object to be coated 10, and the coating material atomized by the rotary atomizing head 16 is in the flat plate shape in the application region by electrostatic force. It is attracted and applied to the article 10 to be coated.

In the application area where the coating material is applied to the flat object 10, the loop conveyor device 12
And D.

The rotation axis of the rotary atomizing head 16 extending in the vertical direction is located between the two parallel straight line portions B and D in the width direction (left and right direction in FIG. 1) and the length direction (in FIG. 1). The supporting device 20 supports the atomizing device 18 so as to be located at the center of the vertical direction).

The rotary atomizing head 1 is supported by the support device 20.
6 is reciprocated along its axis of rotation.

As shown in FIG. 1, a first linear portion B of a loop conveyor device 12 for transporting a flat object 10 to be coated,
An inversion portion C and a second linear portion D, an inversion device 14,
It is preferable that the atomizing device 18 having the rotary atomizing head 16 is housed in the coating booth 22 and is configured to prevent external contamination by the coating material.

The electrostatic coating apparatus for the flat plate-shaped article to be coated operates as follows.

The loop conveyor device 12 is operated to move the chain 24 at a constant speed. In the attachment part A, the flat object 10 is sequentially hung on a hanger 26 connected to the chain 24 at a predetermined pitch.

The atomizing device 18 and the supporting device 20 are operated. The rotary atomizing head 16 of the atomizing device 18 sprays the coating material radially. The support device 20 causes the rotary atomizing head 16 to reciprocate in the vertical direction.

Flat plate-shaped article 10 suspended on a hanger 26
In the first straight line portion B, one surface is uniformly coated.

The flat article 10 is rotated by 180 ° by the reversing device 14 of the reversing portion C.

The other surface of the flat object 10 is uniformly coated in the first straight portion B.

At the removal portion E, the flat object 10 coated on both sides is removed from the hanger 26.

Example 1 A flat plate-shaped object having a width W was coated by using an electrostatic coating apparatus according to the prior art and an electrostatic coating apparatus for a flat plate-shaped object as shown in FIG. went. In the conventional apparatus, the spray distance, that is, the distance R between the rotary atomizing head and the plate-shaped object to be coated is constant and is 250 m.
m. In the conventional device, since there is no straight part,
L = 0.

As a device having a straight line portion, a device as shown in FIGS. 1 and 2 was used, in which the length L of the first and second straight line portions B and D was 700 mm.
The spray distance R is 250 mm.

The uniformity of the film thickness of the flat coating object having the width W coated according to the conventional apparatus and the present invention as described above was as shown in Table 1 below.

Table 1 W (mm) L (mm) Uniformity of film thickness 200 0 ± 7,2% 300 0 ± 11.1% 400 0 ± 19,9% 400 700 ± 6.9% Clear from Table 1 As described above, the coating according to the present invention is superior in the uniformity of the film thickness.

(Embodiment 2) A device as shown in FIGS. 1 and 2, wherein (a) the spray distance R is 150 mm, and the length L of the first and second straight line portions B and D is 5,
(B) the spray distance R is 250 mm, and the length L of the first and second linear portions B and D is 7 mm.
(C) the spray distance R is 350 mm, and the length L of the first and second linear portions B and D is 9 mm.
A flat object having a width W of 400 mm was coated using a device of 00 mm, and the uniformity of each film thickness and the coating efficiency were examined. The results were as shown in Table 2 below.

Table 2 R (mm) L (mm) Uniformity of film thickness Coating efficiency (a) 150 500 ± 4.8% 96% (b) 250 700 ± 6.9% 93% (c) 350 900 ± 9.4% 89% From these results, it can be seen that good results are exhibited when L ≧ 2R.

(Embodiment 3) The apparatus shown in FIGS. 1 and 2 in which the spray distance R is 250 mm and the length L of the first and second straight portions B and D is 700 mm. A flat plate-like article having a width W of 400 mm was applied at intervals d. The results were as shown in Table 3 below.

Table 3 d (mm) Film thickness (μ) Uniformity of film thickness (maximum to minimum) 10 25-26 ± 2.0% 20 25-26 ± 3.8% 40 25-28 ± 5.7 % 60 24 to 30 ± 11.1% 80 24 to 31 ± 12.7% 160 24 to 34 ± 17.2% Since the film thickness uniformity is preferably within ± 10%, these results show that It can be seen that the distance d between the objects to be coated is preferably less than 50 mm. Effects According to the present invention, it is possible to uniformly coat a flat object to be coated.

[Brief description of the drawings]

FIG. 1 is a simplified plan view of an example of an electrostatic coating apparatus for carrying out an electrostatic coating method for a resist coating material according to a preferred embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the device of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Flat object 12 Conveyor device 14 Reversing device 16 Rotary atomizing head 18 Atomizing device 20 Supporting device

Claims (1)

(57) [Claims] 1. A method for electrostatically coating a resist coating on a plate-shaped article for a printed circuit board, wherein the distance from the rotary atomizing head is R,
When the length of the straight line portion of the plate-shaped object to be coated is L, the relationship between L and R satisfies L ≧ 2R, and the plate-shaped object to be coated is rotated at an interval of 50 mm or less. An electrostatic coating method of a resist paint, wherein a resist coating material atomized by a fog head is applied by electrostatic force.