JP2001347633A - Screen printing apparatus and screen printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a screen printing apparatus and a screen printing method, capable of ensuring printing quality by preventing an increase in the viscosity of the paste in a squeegee head. SOLUTION: In the screen printing apparatus for printing cream solder 5 on a substrate by sliding a hermetically closed squeegee head 13 storing the solder 5 on a mask plate 12, valves V1, V2 for supplying drive air to a pressure cylinder for pressing the squeegee head 13 to the mask plate 12 and a cylinder 16 for pressing the cream solder 5 stored in the squeegee head 13 are alternately turned ON/OFF to perform flowing and stirring operation for allowing the cream solder 5 to flow up and down through a throttling part. By this constitution, the flowability of the cream solder 5 is ensured to keep printing quality.

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 and a screen printing method 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 pattern holes formed in accordance with a printing target portion is set on a substrate, and the paste is printed on the substrate through the pattern holes of the mask plate by squeezing.

As a squeezing method for screen printing, a method using a closed squeegee head is known. This method uses a squeegee head provided with a paste storage container, instead of directly supplying the paste onto a mask plate unlike normal screen printing. In this method, the paste in the paste storage container is pressed through the opening in the pattern hole of the mask plate by pressing the paste in the paste storage container while the opening provided on the lower surface of the paste storage container is in contact with the mask plate. Is pushed. Then, the squeegee head is slid on the mask plate to sequentially fill each pattern hole with the paste.

[0004]

However, screen printing using the above-mentioned conventional closed-type squeegee head involves the following.
There were the following problems. As described above, in this method, the paste in the squeegee head is always pressed from above. For this reason, as time passes, the paste increases in viscosity due to pressurization from one direction and the fluidity decreases. The paste with reduced fluidity has a problem that even if the squeegee head is slid on the mask plate, the paste is not sufficiently filled in the pattern holes, so that poor printing is likely to occur.

Accordingly, an object of the present invention is to provide a screen printing apparatus and a screen printing method capable of preventing the viscosity of the paste inside the squeegee head from increasing and ensuring print quality.

[0006]

According to a first aspect of the present invention, there is provided a screen printing apparatus for printing a paste on a substrate through a pattern hole of a mask plate by sliding a squeegee head on the mask plate. Pressing means for pressing the squeegee head against the mask plate; a paste storage section for storing paste in the squeegee head; paste pressing means for pressing the paste in the paste storage section; A printing space in which the paste is stored and brought into contact with the surface of the mask plate, a pressurized paste is provided in a flow path from the paste storage to the printing space, and a printing space before and after in a squeezing direction of the printing space. Two scraping members, each having a wall and having a lower end in contact with the surface of the mask plate, And a flow agitation control means for stirring by flow through the narrowed portion of the paste by controlling the means and the paste pressure means.

According to a second aspect of the present invention, there is provided a screen printing method, wherein a squeegee head in which a paste is stored is slid on the mask plate in a state where the paste is pressed by a paste pressing means, thereby forming a pattern hole in the mask plate. Screen printing method for printing a paste on a substrate via a squeegee head, and a pressurizing means for pressing a paste stored in a paste storage unit in the squeegee head. By controlling the above, the paste is made to flow through a narrowing portion provided between the printing space for containing the pressurized paste and making contact with the surface of the mask plate and the paste storage portion and narrowing the flow path of the paste. A fluid stirring operation for stirring was performed.

[0008] According to the present invention, the paste is supplied through a narrowing portion provided between the printing space in which the pressurized paste is contained and brought into contact with the surface of the mask plate and the paste storing portion to narrow the flow path of the paste. By performing the fluid stirring operation of flowing and stirring, it is possible to prevent the viscosity of the paste from increasing and to secure the fluidity of the paste.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a front view of a screen printing apparatus according to one embodiment of the present invention, FIG. 2 is a side view of the screen printing apparatus according to one embodiment of the present invention, and FIG. 3 is a screen printing apparatus according to one embodiment of the present invention. FIG. 4 is an explanatory view of the flow stirring operation of the cream solder in the screen printing according to the embodiment of the present invention.

First, the structure of the screen printing apparatus will be described with reference to FIGS. 1 and 2, the substrate positioning unit 1 is configured by disposing a substrate holding unit 2 on a moving table (not shown). The substrate 3 to be screen-printed is held by a clamper 4 of the substrate holding unit 2, and by driving a moving table (not shown), the substrate 3 held by the substrate holding unit 2 is positioned in the horizontal and vertical directions. .

A screen mask 10 is provided above the positioning section 1. The screen mask 10 is configured by mounting a mask plate 12 on a holder 11, and a pattern hole 12 a corresponding to a printing portion of the substrate 3 to be printed is formed in the mask plate 12.

A squeegee head 13 is arranged on the screen mask 10 so as to be able to move up and down by a head elevating unit 20. The head elevating unit 20 includes a cylinder 22 erected on a plate member 21. The cylinder 22 is connected to the air source 18 via a valve V1 and a regulator R1. At the lower end of the rod 22a of the cylinder 22,
The squeegee head 13 is connected via the connecting member 15.

By driving the cylinder 22, the squeegee head 13 moves up and down with respect to the mask plate 12 and presses the squeegee head 13 against the mask plate 12. The head elevating unit 20 is a squeegee head 1
3 is a lifting means for raising and lowering the screen mask 3 with respect to the screen mask 10. Also, the cylinder 22 is a squeegee head 1
3 is a pressing means for pressing the mask plate 3 against the mask plate 12. At this time, the lifting / pressing control is performed by the control unit 19.
This is performed by controlling the valve V1 and the regulator R1.

Sliders 23 are fixed at both ends to the lower surface of the plate member 21 of the head elevating unit 20, and the slider 23 is slidably fitted on a guide rail 24 provided on the upper surface of the frame 25. I have. A nut 26 is connected to the lower surface of the plate member 21, and a feed screw 27 screwed to the nut 26 is driven to rotate by a motor 28.

By driving the motor 28, the plate member 21 moves horizontally, and therefore the head lifting / lowering unit 20 is moved.
Is also moved horizontally. By driving the motor 28 with the squeegee head 13 lowered, the squeegee head 13 moves horizontally on the mask plate 12. That is, the motor 28, the feed screw 27, and the nut 26 are moving means for horizontally moving the squeegee head 13 on the mask plate 12.

At the lower part of the squeegee head 13, there is provided a printing section 14 which abuts on the surface of the mask plate 12 and fills the pattern holes 12a with the cream solder 5 as a paste. The structure of the printing unit 14 will be described with reference to FIG. In FIG. 3, reference numeral 30 denotes a main body, which is a block-shaped member elongated in the width direction of the mask plate 12. The length of the main body 30 is set so as to cover the width of the substrate 3 to be printed as shown in FIG. Main unit 30
Is formed with a concave portion 30a in which the cartridge 31 storing the cream solder 5 is detachably mounted.

The cartridge 31 is a reservoir (paste reservoir) for the cream solder 5 in which a predetermined amount of the cream solder 5 is stored in advance, and is mounted on the main body 30 at the time of printing. A pressure plate 32 for pressing the cream solder 5 inside is fitted into the opening on the upper surface of the cartridge 31. The pressure plate 32 is connected to the rod 16a of the cylinder 16 disposed above, and by driving the cylinder 16,
The pressure plate 32 moves up and down in the cartridge 31.

The cylinder 16 is connected to an air source 18 via a valve V2 and a regulator R2. The regulator R2 can set the pressure of the air supplied to the cylinder 16 according to the pressure setting signal from the control unit 19, and pushes down the cream solder 5 in the cartridge 31 at a predetermined pressure.

The bottom of the cartridge 31 has a cream solder 5
The extruding plate 31a has a large number of openings 31b. When the pressing plate 32 is pressed downward by the cylinder 16, the cream solder 5 in the cartridge 31 is pressed, and the pressing plate 31a is pressed.
Through the opening 31b. Cylinder 1
The pressing plate 6 and the pressing plate 32 serve as a paste pressing means for pressing the cream solder 5 which is a paste. The control of the pressurization at this time is performed by controlling the valve V2 and the regulator R2 by the control unit 19.

At the bottom of the main body 30, a cartridge 31 is provided.
A diaphragm plate 34 provided with a large number of openings 34a is mounted similarly to the extrusion plate 31a. When the cream solder 5 is extruded by the cylinder 16, the extruding plate 3
It passes through the opening 31b of 1a and the opening 34a of the diaphragm plate 34 in two stages and moves downward. The extruded cream solder 5 forms a space formed below the main body 30, that is, two scraping members 36 </ b> A and 36 </ b> B disposed obliquely inside the lower part of the main body 30 and the lower surface of the main body 30. And arrives at the printing space 35 surrounded by.

The scraping members 36A and 36B form front and rear walls of the printing space 35 in the squeezing direction, and when the squeegee head 13 is lowered, the scraping members 36A and 36B are formed.
The lower end of 6B contacts the surface of the mask plate 12. During the printing operation, the printing space 35 contains the pressurized cream solder 5 and brings the cream solder 5 into contact with the surface of the mask plate 12 through the opening between the scraping members 36A and 36B.

The pressure plate 32 is depressed so that the cartridge 31
By pressing the cream solder 5 inside, the cream solder 5 passes through the extruding plate 31a and the squeezing plate 34 and moves into the printing space 35. The flow path in the movement path of the cream solder 5 is provided with a narrowed portion whose cross-sectional area is narrowed by a number of small openings 31b and 34a, and the pressurized cream solder 5 passes through the narrowed portion. By doing
The viscosity of the cream solder 5 is reduced, and is modified to a property suitable for screen printing.

In the screen printing, the cream solder 5 inside is pressed by the pressing plate 32, and the squeegee head 13 in a state in which the cream solder 5 modified to the appropriate viscosity as described above is filled in the printing space 35. Is slid on the mask plate 12. Thus, the paste in the printing space 35 is filled into the pattern holes 12a of the mask plate 12 through the openings between the scraping members 36A and 36B.

Then, by moving the squeegee head 13, the cream solder 5 is sequentially filled in the respective pattern holes 12a. When the cream solder 5 is filled in all the pattern holes 12a, the substrate holding unit 2 is lowered to release the plate. That is, the cream solder 5 in the pattern hole 12a descends together with the substrate 3 and
, Whereby the screen printing of the cream solder 5 on the substrate 3 is completed.

Next, the flow stirring operation of the cream solder 5 performed to maintain the viscosity of the cream solder 5 at an appropriate value in the printing process of the cream solder 5 will be described with reference to FIG. In screen printing using a closed type squeegee head, since the cream solder 5 is constantly pressed from above in the squeegee head 13 at a predetermined pressure, the viscosity tends to increase with time.
When the viscosity of the cream solder 5 is increased, the fluidity is reduced, and the filling of the pattern holes during the screen printing is likely to be insufficient, which causes printing failure. Therefore, it is required to maintain the viscosity of the cream solder 5 appropriately. This fluid stirring operation is performed for such a purpose.

This flow stirring operation is performed by flowing the cream solder 5 in the printing section 14 in the vertical direction while the printing section 14 in which the cream solder 5 is stored is in contact with the mask plate 12. Will be First, as shown in FIG. 4A, the pressure plate 32 connected to the rod of the cylinder 16 is raised, and the rod of the cylinder 22 (see FIG. 3) is projected to press the printing unit 14 against the mask plate 12. . Accordingly, the cream solder 5 in the printing space 35 flows upward through the opening 34a of the aperture plate 34,
The cream solder 5 located above the aperture plate 34 flows into the cartridge 31 above through the opening 31b.

Thereafter, the cream solder 5 is caused to flow in the reverse direction. That is, as shown in FIG. 4B, the pressing plate 32 is lowered by the cylinder 16 and the rod of the cylinder 22 (see FIG. 3) is immersed to release the pressing of the printing unit 14 against the mask plate 12. Thus, the cream solder 5 in the cartridge 31 flows downward through the opening 31b, and the cream solder 5 located above the aperture plate 34 enters the lower printing space 35 through the opening 34a. Flow.

The operations shown in FIGS. 4A and 4B are repeatedly performed. That is, the cream solder 5 is repeatedly stirred in the vertical direction by flowing the cream solder 5 repeatedly in the vertical direction through the throttle portion provided between the printing space 35 and the cartridge 31 to narrow the flow path of the cream solder 5. And fluidity is secured. Therefore, the pattern holes 12a are filled well during screen printing, and the print quality is maintained.

As shown in FIG. 4 (c), the flow stirring operation is performed by controlling the valves V1 and V2 for connecting and disconnecting the air for driving the cylinders 22 and 16, respectively, by the control unit 19. ON / OFF of V2
Are alternately switched. Therefore,
The control unit 19 is a flow stirring control unit that controls the cylinder 22 and the cylinder 16 to flow and stir the cream solder 5 through the openings 31b and 34a.

The regulators R1 and R2 are also controlled together with the ON / OFF switching of the valves V1 and V2 to individually control the pressing force applied to the cream solder 5 and the pressing force for pressing the entire printing unit 14. You may do so. Thereby, the degree of the flow of the cream solder 5 can be appropriately set, and the stirring effect can be improved.

[0031]

According to the present invention, the pressurized paste is contained between the printing space in which the paste is stored and brought into contact with the surface of the mask plate and the paste storage section, and the narrowing section for narrowing the flow path of the paste is provided. Since the fluid stirring operation for flowing and stirring the paste is performed, the viscosity of the paste is prevented from increasing, the fluidity of the paste is secured, and the printing quality can be maintained.

[Brief description of the drawings]

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

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

FIG. 3 is a partial sectional view of a squeegee head of the screen printing apparatus according to the embodiment of the present invention;

FIG. 4 is an explanatory view of a flow stirring operation of cream solder in screen printing according to an embodiment of the present invention.

DESCRIPTION OF SYMBOLS 3 Substrate 5 Cream solder 12 Mask plate 12a Pattern hole 13 Squeegee head 14 Printing unit 16 Cylinder 19 Control unit 22 Cylinder 31 Cartridge 32 Pressure plate 34 Aperture plate 35 Printing space

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41M 1/12 B41M 1/12 H05K 3/12 610 H05K 3/12 610N 3/34 505 3/34 505D ( 72) Inventor Seiichi Miyahara 1006 Kadoma, Kazuma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Kimiyuki Yamazaki 1006 Odaka, Kazuma Kadoma, Osaka Pref. FC09 FD01 FD07 FD17 FD35 2H113 AA01 AA05 BA10 BB22 BC12 CA17 FA54 5E319 BB05 CD29 5E343 AA02 BB54 BB72 DD03 FF04 FF12 GG06

Claims (2)

[Claims] 1. A screen printing apparatus for printing a paste on a substrate through a pattern hole of a mask plate by sliding a squeegee head on the mask plate, wherein the squeegee head is pressed against the mask plate. Pressing means and a paste storage part for storing the paste in the squeegee head, paste pressing means for pressing the paste in the paste storage part, and a printing space for receiving the pressed paste and contacting the surface of the mask plate; A pressurized paste formed in a flow path from the paste reservoir to the printing space and a front and rear wall in a squeezing direction of the printing space, and a lower end portion of the pressurized paste contacts the surface of the mask plate. By controlling the two scraping members provided in contact with each other and the pressing means and the paste pressing means, the Screen printing apparatus characterized by comprising a flow agitation control means for stirring by flowing through the throttle portion. 2. A paste is printed on a substrate through a pattern hole of a mask plate by sliding a squeegee head containing a paste therein on a mask plate in a state where the paste is pressed by a paste pressing means. A screen printing method, wherein a pressing means for pressing the squeegee head against the mask plate and a paste pressing means for pressing the paste stored in the paste storing section in the squeegee head are controlled to control the printing. A fluid stirring operation is performed in which the paste is flowed and stirred through a narrowing portion provided between the printing space in which the pressurized paste is stored and brought into contact with the surface of the mask plate and the paste storage portion to narrow the flow path of the paste. A screen printing method characterized by performing the following.