JP2000218762A - Screen printing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screen printing device and a screen printing method by which it is possible to accurately measure printing pressure and stabilize the print quality. SOLUTION: A mask plate 12 with pattern holes is brought into contact with a base 6 and a cream solder 16 is printed by a squeegee 15 on the base 6 as the operating function of the screen printing device. In this device, a single load cell 2 is provided which detects a pressing load in the printing pressure application direction of a cylinder 14 which applies printing pressure by pressing the squeegee 15 to the mask plate 12 during printing. The load to be applied to the cylinder 14 is controlled by a pressure conversion part 22 and a control part 21 in accordance with detection results. Thus the dispersion of the printing pressure by the differences of the devices used is removed by eliminating a measurement error attributed to a difference in the pressing direction and also measuring the printing pressure of the two squeegees using a single detection means to accurately measure the printing pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing apparatus for printing paste such as cream solder or conductive paste on a substrate.

[0002]

2. Description of the Related Art In an electronic component mounting process, screen printing is used as a method for printing paste such as cream solder or conductive paste on a substrate. In this method, a mask plate having a pattern hole opened according to a printing target portion is set on a substrate, a paste is supplied on the mask plate, and a squeegee is slid, so that the squeegee slides on the substrate through the pattern hole. Prints the paste.

In this screen printing, when printing is performed by sliding a squeegee, it is necessary to press the squeegee against the mask plate with an appropriate pressing load (hereinafter referred to as "printing pressure"). For this reason, a load measuring device such as a load cell for measuring the printing pressure of a squeegee has conventionally been installed in a screen printing apparatus. Conventionally, as a cylinder that generates a pressing load that presses the squeegee against the mask plate, a double rod type having rods in both up and down directions is used, a load cell is arranged above the cylinder, and the load transmitted by the upper rod is This was detected and this load value was regarded as the printing pressure value.

[0004]

However, the conventional printing pressure measuring method has the following problems. First, even if both rod type cylinders are used at the same air pressure, the load actually generated by the cylinder differs depending on the direction in which the load acts. This is because the sliding resistance of the piston in the cylinder differs depending on the sliding direction. Therefore, even if the air pressure condition is set based on the load obtained via the upper rod, there is a problem that the printing pressure at which the squeegee is actually pressed against the mask plate cannot be set with good reproducibility. In the past, since the printing pressures of the front and rear squeegees were measured by separate load cells, the measurement results fluctuated due to the difference between the load cells, and the printing pressure set based on the measurement results fluctuated. As described above, the conventional screen printing apparatus has a problem that the printing pressure measurement cannot be performed with high accuracy and the printing quality varies.

Accordingly, an object of the present invention is to provide a screen printing apparatus capable of performing printing pressure measurement with high accuracy and stabilizing printing quality.

[0006]

According to a first aspect of the present invention, there is provided a screen printing apparatus in which a mask plate provided with pattern holes is brought into contact with a substrate, paste is supplied onto the mask plate, and a squeegee is slid. A screen printing apparatus for printing a paste on a substrate through the pattern holes, wherein the printing pressure is applied by pressing the squeegee against a mask plate during printing, and the printing pressure applying means. A detecting means for detecting a pressing load in a printing pressure application direction to the squeegee, and a printing pressure setting means for setting the printing pressure to a required printing pressure value by controlling the printing pressure applying means based on the detection result.

According to a second aspect of the present invention, there is provided a screen printing apparatus according to the first aspect, wherein the squeegee includes two front and rear squeegees, and a single detecting unit detects a pressing load of the two squeegees. .

According to the present invention, the printing pressure is measured by detecting the pressing force in the direction in which the squeegee is pressed against the mask plate by the printing pressure applying means, so that a measurement error caused by the difference in the pressing direction is eliminated. Thus, accurate printing pressure measurement can be performed. Further, by performing printing pressure measurement on two squeegees using a single detection unit, it is possible to eliminate variations due to instrumental differences.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a side view of a screen printing apparatus according to an embodiment of the present invention, FIG. 2 is a partial side view of a squeegee of the screen printing apparatus, and FIGS. 3A and 3B are squeegee pressing loads of the screen printing apparatus. FIG. 4 is a partial side view of a squeegee of the screen printing apparatus.

First, the structure of the screen printing apparatus will be described with reference to FIGS. In FIG. 1, a substrate positioning unit 1 is configured by stacking an X-axis table 2, a Y-axis table 3, and a θ-axis table 4, and further arranging a Z-axis table 5 thereon. A substrate holding section 7 for holding the substrate 6 by a clamper 8 is provided on 5.

A screen mask 10 is provided above the substrate positioning section 1. The screen mask 10 is configured by mounting a mask plate 12 on a holder 11. A squeegee unit 13 is arranged on the screen mask 10 so as to be able to reciprocate in the horizontal direction. Substrate 6
The squeegee provided on the squeegee unit 13 is supplied by supplying cream solder, which is a paste, onto the mask plate 12 while the squeegee unit 13 is in contact with the lower surface of the mask plate 12. Thereby, the cream solder 16 is printed on the substrate 6 through the pattern holes provided in the mask plate 12.

The squeegee unit 13 includes two front and rear squeegees 15, each of which is connected to a rod of a cylinder 14. The squeegee 15 comes into contact with the mask plate 12 by driving the cylinder 14 to lower the squeegee 15, and presses the mask plate 12 with a predetermined pressing load. This pressing load is applied to the squeegee 15
Is a printing pressure necessary to normally scrape the cream solder and perform good printing, and the cylinder 14 is a printing pressure applying means. The cylinder 14 is connected to an air source 23 via a pressure converter 22. The pressure converter 22 is a controller 2
1 to set the pressure of the air supplied to the cylinder 14. That is, the pressure conversion unit 22 and the control unit 21 serve as a printing pressure setting unit that sets the printing pressure by controlling the air pressure of the cylinder 14.

A load cell 20 is provided on the side of the screen mask 10. As shown in FIG. 2, the squeegee unit 13 is positioned on the load cell 20, and the squeegee 15 is brought into contact with the load cell 20 by driving the cylinder 14 to lower the squeegee 15. The pressing load at is detected. That is, the load cell 20 is a detecting unit. The detection result by the load cell 20 is sent to the control unit 21.

Here, only one load cell 20 is provided, and the squeegee unit 13 is moved so that the two squeegees 15 are sequentially brought into contact with the load cell 20, so that two load cells 20 can be used using a single load cell 20. Squeegees 1
No. 5 printing pressure can be detected, and accurate printing pressure detection can be performed without any instrumental difference inherent to the load cell. Further, when the printing pressure is detected by the load cell 20, since the operation direction of the cylinder 14 is the same as the actual printing pressure application direction at the time of printing, the difference in the generated load value due to the difference in the sliding direction in the cylinder 14 is detected. Does not exist, and the load can be detected under the same conditions as the actual printing pressure.

Next, measurement of the squeegee pressing load and setting of the printing pressure calculation formula in this screen printing apparatus will be described with reference to FIG. The measurement of the squeegee pressing load is performed in order to obtain a correct relationship between the load value of the squeegee 15 pressing the screen mask by the cylinder 14 and the pressure value of the air supplied to the cylinder 14. As shown in FIG. 3A, the data point d of the detected load at each air pressure set by the control unit 21
Is replaced by an appropriate approximation line L to obtain a graph representing a printing pressure calculation formula.

When the printing pressure value F is set according to the printing conditions at the time of actual printing, the printing pressure value F is set as shown in FIG. Is determined. By controlling the air pressure supplied to the cylinder 14 by the pressure conversion unit 22 according to the pressure value P, the squeegee 15 always presses the screen mask at the predetermined printing pressure value F, and prints under the correct conditions. It can be carried out.

As a method of measuring the printing pressure value F, instead of directly pressing the load cell with the tip of the squeegee, a load measuring attachment 24 is attached to the squeegee 15 as shown in FIG. 20 may be transmitted. By using such a method, the printing pressure value can be measured even when the load cell cannot be directly pressed by the squeegee.

[0018]

According to the present invention, the printing pressure is measured by detecting the pressing load in the printing pressure application direction in which the squeegee is pressed against the screen mask by the printing pressure application means. It is possible to perform accurate printing pressure measurement by eliminating the measurement error. Also preferably, by performing printing pressure measurement on two squeegees using a single detecting means, it is possible to eliminate variations due to instrumental differences.

[Brief description of the drawings]

FIG. 1 is a side view of a screen printing apparatus according to an embodiment of the present invention.

FIG. 2 is a partial side view of a squeegee of the screen printing apparatus according to the embodiment of the present invention.

3A is a graph showing a relationship between a squeegee pressing load and an air pressure of the screen printing apparatus according to one embodiment of the present invention. FIG. 3B is a graph showing a relationship between a squeegee pressing load and air pressure of the screen printing apparatus according to one embodiment of the present invention. Graph showing the relationship with air pressure

FIG. 4 is a partial side view of a squeegee of the screen printing apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate positioning part 6 Substrate 12 Mask plate 14 Cylinder 15 Squeegee 20 Load cell 21 Control part 22 Pressure conversion part

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takaaki Sakagami 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. F term (reference) 2C035 AA06 FA27 FA31 FD01 FD15 FD17 FD22 5E319 BB05 CD29 CD51 5E343 DD03 FF02 FF04

Claims (2)

[Claims] 1. A screen for printing a paste on a substrate through said pattern holes by bringing a mask plate provided with pattern holes into contact with a substrate, supplying a paste onto the mask plate and sliding a squeegee. A printing apparatus, comprising: a printing pressure application unit that applies the printing pressure by pressing the squeegee against a mask plate during printing; and a detection unit that detects a pressing load in a printing pressure application direction to the squeegee by the printing pressure application unit. And a printing pressure setting unit that sets the printing pressure to a required printing pressure value by controlling the printing pressure applying unit based on the detection result. 2. The screen printing apparatus according to claim 1, wherein said squeegee includes two front and rear squeegees, and a single detecting means detects a pressing load of the two squeegees.