JPH05309822A - Screen printing press - Google Patents

Abstract

PURPOSE:To reduce a load to be applied to a squeegee at the time of printing in accordance with an open part formed in a screen and to perform a uniform and stable printing by a method wherein the squeegee is mounted on a holder inclinedly in the travel direction of the holder. CONSTITUTION:On a pair of drive shafts 8, substantially the centers of squeegee holders 9 are rotatably mounted. In the vicinity of one end of each of the squeegee holders 9, a guide bolt 21 is vertically erected. On a squeegee support member 6 supporting air cylinders 7, guide grooves 22 shaped into a circular arc having a center on the position of the drive shaft 8 are formed so as to fit with the guide bolts 21. The squeegee holders 9 are rotated about the drive shafts 8. The guide bolts 21 are moved along the guide grooves 22. The squeegee holders 9 are set at an angle realizing a minimum load in accordance with the state of a pattern of an open part of a screen. Nuts are screwed to the guide bolts 21 to fix the squeegee holders 9 to the squeegee support member 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing machine for printing a paste such as cream solder through an opening formed in a screen.

[0002]

2. Description of the Related Art FIGS. 5 and 6 show an example of the configuration of a conventional screen printer. In FIGS. 5 and 6, the outer periphery of the screen 2 is attached to the screen mounting base 1, and a table 4 on which a substrate 3 is mounted is provided at the lower part of the screen 2 so as to be able to move up and down. Further, a squeegee support member 6 mounted on a pair of parallel guide shafts 5 movably in the direction of arrow AA is provided on the upper portion of the screen 2. Further, a pair of air cylinders 7 are vertically mounted on the squeegee support member 6, and a squeegee holder 9 is fixed to a drive shaft 8 of each air cylinder 7. A squeegee 10 is attached to the lower surface of the squeegee holder 9.

In the screen printing machine constructed as described above, cream solder (not shown) is supplied onto the screen 2, and the table 4 is raised to bring the substrate 3 into close contact with the screen 2. Next, the squeegee holder 9 is lowered by the air cylinder 7 to bring the squeegee 10 into contact with the screen 2. Then, the squeegee support member 6 is moved in the direction of arrow AA, and the cream solder is printed on the substrate 3 through the openings 11 having a predetermined pattern formed on the screen 2.

[0004]

Recently, the mounting density of electronic parts mounted on the substrate 3 has been increasing, and the density is 10 pieces / cm ^{2 to} 40 pieces / cm ² . Therefore, the load applied to the tip of the squeegee 10 becomes large, and the squeegee 10
There is a problem that the deformed state of the tip of the is changed depending on the land shape on the substrate 3 to be printed, and it becomes difficult to stably print the cream solder. Also, downsizing of parts, IC
As the pitch of the connector and the connector is narrowed, the opening area of the opening 11 of the screen 2 becomes smaller.

In particular, the opening 12 corresponding to the land of the rectangular flat package (QFP) as shown in FIGS. 7 and 8.
As described above, when a plurality of elongated openings 12 are provided in parallel on each of the four sides, the ratio of the dimensions of the long sides and the short sides of the openings 12 becomes large. Therefore, since the stroke direction A of the squeegee 10 is the direction of the long side or the short side of the opening 12, printing conditions are completely different and stable printing cannot be performed. That is, the load is small when the squeegee 10 moves in the direction parallel to the long side of the opening 12, and the load becomes large when the squeegee 10 moves in the direction parallel to the short side.

Since various electronic parts are mounted on the substrate 3, lands having various patterns are formed. For this reason, although the load at the time of printing changes variously, the magnitude of the load when the squeegee 10 moves as a whole has directionality, and as a result, stable cream solder printing cannot be performed.

The present invention has been made in view of such a situation, and paste such as cream solder can be stably printed on lands of a board having a high mounting density, and printing quality can be improved. The purpose is to provide a screen printing machine.

[0008]

According to a first aspect of the present invention, there is provided a screen printing machine in which a paste is supplied onto a screen 2 having openings 11 having a predetermined pattern and a squeegee 10 supported by a holder 9 is screened. In a screen printing machine that moves in a fixed direction on 2 to print the paste on the substrate 3 placed on the table 4, the squeegee 10 is attached to the holder 9 while being inclined with respect to the moving direction of the holder 9. It is characterized by

A screen printing machine according to a second aspect is characterized in that a holder 9 for supporting a squeegee 10 is rotatable.

[0010]

In the screen printing machine according to the first aspect, the squeegee 10 is tilted at a predetermined angle with respect to the moving direction to reduce the load applied to the squeegee 10 by the opening 11 formed in the screen 2 during printing. In addition, uniform printing can be performed and stable printing can be performed.

In the screen printing machine according to the second aspect, since the squeegee holder 9 can be attached to the printing machine at an arbitrary angle within a predetermined angle range, the squeegee 10 can be attached.
The inclination angle of can be easily set.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the screen printing machine of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, portions corresponding to those of the conventional example shown in FIGS. 5 and 6 are denoted by the same reference numerals, and description thereof will be omitted as appropriate. The feature of this embodiment is that the drive shaft 8 of the air cylinder 7 is
On the other hand, the squeegee holder 9 is rotatably attached, and the configuration of the other parts is almost the same as the conventional example. A squeegee holder 9 is rotatably attached to each of the pair of drive shafts 8, and a guide bolt 21 is vertically provided near one end of the squeegee holder 9. Further, the squeegee support member 6 supporting the air cylinder 7 is provided with arcuate guide grooves 22 centered on the drive shaft 8 at positions aligned with the guide bolts 21. The squeegee holder 9 rotates about the drive shaft 8, and the guide bolt 21 is guided by the guide groove 22 to move.

According to the present embodiment, the squeegee holder 9 is set to an angle with the least load according to the state of the pattern of the openings 11 of the screen 2 shown in FIG.
The squeegee holder 9 can be fixed to the squeegee support member 6 by screwing a nut (not shown) onto the squeegee 1. As a result, even when the mounting density of electronic components on the substrate 3 is high, the load applied to the squeegee 10 can be reduced, and the cream solder can be properly pressed into the opening 11 of the screen 2. Therefore, stable printing conditions can be obtained, soldering quality can be improved, and wear of the squeegee 10 can be reduced. Furthermore, for the QFP with a small lead pitch of 0.3 mm,
It is possible to apply cream solder to the land by a printing method.

In the above embodiment, the case where the squeegee holder 9 is rotated has been described. However, as shown in FIGS. 2 and 3, the squeegee holder 9 is fixed to the squeegee support member 6,
Attach the squeegee 10 that is attached to the squeegee holder 9 to the screw 3
You may make it move by 1. That is, the screw holes 32 are formed in the vicinity of the front end and the rear end of both side walls of the squeegee holder 9 having a U-shaped cross section, and the screws 31 are screwed into the pair of screw holes 32. Squeegee 1
The angle of 0 with respect to the squeegee holder 9 is adjusted. In addition,
Reference numeral 33 shown in FIG. 3 is a squeegee rubber attached to the tip of the squeegee 10.

As shown in FIG. 4, the squeegee 10 may be fixed to the squeegee holder 9 by inclining it at a predetermined angle from the beginning.

[0017]

As described above, according to the screen printing machine of the first aspect, since the squeegee is attached so as to be inclined with respect to the moving direction of the squeegee holder, the printing is performed by the opening formed in the screen. It is possible to reduce the load on the squeegee and to make it uniform, and to perform stable printing.

According to the screen printing machine of the second aspect, since the squeegee holder is rotatable, the inclination angle of the squeegee can be easily set.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a squeegee holder according to an embodiment of a screen printing machine of the present invention.

FIG. 2 is a perspective view showing the structure of a squeegee holder according to another embodiment of the present invention.

FIG. 3 is a side view showing a state in which a squeegee is attached to the squeegee holder shown in FIG.

FIG. 4 is a bottom view showing the configuration of a squeegee holder according to another embodiment of the present invention.

FIG. 5 is a front view showing a schematic configuration of an example of a conventional screen printing machine.

FIG. 6 is a plan view of FIG.

7 is a plan view showing an example of a pattern of openings of the screen shown in FIG.

8 is a cross-sectional view taken along the line BB of FIG.

[Explanation of symbols]

 2 screen 3 substrate 4 table 9 squeegee holder 10 squeegee 11, 12 opening

Claims (2)

[Claims] 1. A paste is supplied onto a screen on which openings having a predetermined pattern are formed, and a squeegee supported by a holder is moved in a fixed direction on the screen,
A screen printing machine for printing the paste on a substrate placed on a table, wherein the squeegee is attached to the holder while being inclined with respect to a moving direction of the holder. 2. The screen printing machine according to claim 1, wherein a holder for supporting the squeegee is rotatable.