JP2003334925A - Screen printing apparatus and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a screen printing apparatus capable of performing high speed printing and preventing the waste of paste or lowering of quality, and to provide a screen printing method using the same. <P>SOLUTION: Screen printing for bringing a mask plate 12 into contact with a substrate 6 and performing squeezing in two forward and reverse directions by a squeezing head 13 is equipped with two squeegees 16A and 16B. In the operation pattern at the time of a squeegee changeover process, the preceding squeegee 16A is allowed to fall with respect to a mask plate 12 after the squeezing head 13 arrives at the moving end part, and the succeeding squeegee 16B is allowed to be spaced apart from the mask plate 12. The operation pattern is set so that the squeegee 16A is brought into contact with the mask plate 12 without being horizontally moved in the squeezing direction in the next squeezing operation. By this constitution, trouble caused by that the cream solder 17 bonded to the lower end of the squeegee 16A is turned to the back side of the squeezing surface can be prevented. <P>COPYRIGHT: (C)2004,JPO

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 Screen printing is used as a method of printing paste such as cream solder or conductive paste on a substrate in an electronic component mounting process. This method, by contacting the substrate with a screen mask provided with a pattern hole according to the site to be printed, by supplying the paste on the screen mask and sliding the squeegee,
The paste is printed on the substrate through the pattern holes.

Generally, a screen printing apparatus reciprocates a squeegee head equipped with a pair of squeegees so that printing can be performed twice by one reciprocation. Each time the moving direction of the squeegee head is reversed. Further, the squeegee is switched by alternately moving up and down the two squeegees. That is, when squeezing in one direction, the squeegee on the printing side slides on the mask plate,
The squeegee on the non-printing side rises above the upper surface of the mask plate and moves away from it.

In the screen printing of the reciprocating operation by such a pair of squeegees, the height for raising the squeegee on the non-printing side tends to be set as low as possible in recent years for the purpose of speeding up the printing operation. With such a setting, there is an advantage that the up / down allowance in the squeegee switching operation can be reduced and the switching operation can be performed in a short time.

[0005]

However, in the screen printing method for the purpose of high-speed printing, the following problems occur due to the wraparound of the paste. That is, in the above method, since the squeegee on the non-printing side moves slightly elevated from the mask plate, the paste adhered to the lower end of the squeegee is dragged on the upper surface of the mask plate, and dragging of the paste occurs. It's easy to do.

When the squeegee is switched for squeegeeing in the other direction after squeegeeing in one direction is completed, the squeegee with the paste dragged is moved in the opposite direction to the squeegee starting point. After this, the squeegee was lowered with respect to the mask plate. Therefore, in this operation, there occurs a phenomenon that the paste attached to the lower end of the squeegee wraps around to the back side of the squeegee, that is, the back surface of the squeegee surface in a new squeegee operation. In this way, the paste that wraps around the back surface of the squeegee surface outside the printing range is not scraped into the printing range by the squeegee, but remains attached to the mask plate.

The adhesion of the paste outside the printing range occurs each time the squeezing operation is repeated, so that the yield of the paste is reduced in the printing operation. When such an adhered paste is collected and used, the paste that has been in the adhered state for a long time is excessively dried, resulting in a situation in which the print quality is impaired. As described above, in the conventional screen printing, there is a problem that the paste is wasted and the quality is deteriorated when the squeegee is switched.

Therefore, an object of the present invention is to provide a screen printing apparatus and a screen printing method which enable high speed printing and prevent waste of paste and deterioration of quality.

[0009]

According to a first aspect of the present invention, there is provided a screen printing apparatus in which a mask plate having a pattern hole is brought into contact with a substrate, a paste is supplied onto the mask plate, and a squeegee is slid. A screen printing device for printing paste on a substrate through the pattern holes, the clamp member clamping both end faces of the substrate in the squeezing direction and abutting against the lower surface of the mask plate; A squeegee head having two squeegees arranged for squeezing operation, a moving means for reciprocating the squeegee head in the squeegee direction, and an elevating means for individually elevating the squeegee on the mask plate are provided. The squeegee head of the clamp member has reached the moving end point in the squeegee operation in one direction. The position directly below the squeegee of the preceding side in state has a size including the contact range of the mask plate.

In the screen printing method according to a second aspect of the present invention, the mask plate having the pattern holes is brought into contact with the substrate, the paste is supplied onto the mask plate, and the mask plate is arranged for squeezing operation in the forward and reverse directions. A screen printing method for printing a paste on a substrate through the pattern holes by moving a squeegee head equipped with two squeegees on the mask plate and sliding the squeegee. In the squeegeeing direction, the squeegee on the trailing side is brought into contact with the mask plate and the squeegee on the leading side is separated from the mask plate, and the squeegee head is moved in the forward direction to perform the squeegeeing operation. Of the two squeegees, the squeegee on the trailing side in the squeegee direction contacts the mask plate. In the process of repeating the reverse squeegee process of performing the squeegee operation in the reverse direction with the squeegee on the leading side separated from the mask plate, and the process of repeating the forward squeegee process and the reverse process squeegee process. Includes a squeegee switching step of lowering the squeegee on the leading side with respect to the mask plate after reaching the moving end point and separating the squeegee on the trailing side from the mask plate, and in the squeegee switching step, the squeegee on the leading side is By abutting against the mask plate without horizontally moving in the squeegeeing direction in the next squeezing operation, it is possible to prevent the paste adhering to the lower end portion of the squeegee on the leading side from wrapping around to the back side of the squeegee surface.

According to the present invention, in the squeegee switching step when reversing the squeegee direction, the leading side squeegee is brought into contact with the mask plate without horizontally moving in the squeegee direction in the next squeegee operation. It is possible to prevent the paste adhering to the lower end portion of the squeegee on the leading side from wrapping around to the back side of the squeegee surface to enable high-speed printing, and to prevent waste of the paste and deterioration of quality.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. 1 is a sectional view of a screen printing apparatus according to an embodiment of the present invention, FIG. 2 is a partial sectional view of an embodiment of the present invention, and FIGS. 3 and 4 are screen printing methods according to an embodiment of the present invention. FIG.

First, the structure of the screen printing apparatus will be described with reference to FIG. In FIG. 1, a screen printing device 1
Is configured by disposing the screen printing unit 10 above the substrate positioning unit 3. The board positioning unit 3 is XYZ.
The substrate holding unit 5 is arranged on the table 4, and the substrate 6 is held on the substrate holding unit 5. The board 6 is clamped by clampers 7A and 7B (clamping members) at both ends in the squeezing direction during printing. In this clamped state, the clamper 7
A and 7B are in contact with the lower surface of the mask plate 12.

A screen printing unit 10 is arranged above the substrate positioning unit 3. Screen printing section 10
Is provided with a mask plate 12 extended on a holder frame 11. A squeegee unit 13 is arranged on the mask plate 12, and the squeegee unit 13 is connected to the moving means 20. The moving means 20 includes a holding table 21, a feed screw 22, a nut 23, and a motor 25.
The squeegee unit 13 coupled to the nut 23 via the bracket 24 reciprocates in the printing direction (direction of arrow a) by rotating the motor 25 in the forward and reverse directions.

The squeegee unit 13 is connected to a bracket 24 via a plate 14, and the plate 14 is provided with squeegee lifting mechanisms 15A and 15B.
By driving the squeegee lifting mechanisms 15A and 15B, the squeegees 16A and 16B are individually lifted and lowered. The squeegee lifting mechanisms 15A and 15B are squeegees 16A and 16B.
It is an elevating means that raises and lowers individually. The mask plate 12 to which the paste cream solder 17 is supplied in a state where the substrate 6 is brought into contact with the lower surface of the mask plate 12.
By sliding the squeegee 16A, 16B on the
Cream solder 1 on the substrate 6 through a pattern hole (not shown)
7 is printed.

Here, the clampers 7A and 7B have a size including the position directly below the squeegee on the leading side when the squeegee head 13 reaches the moving end point in the squeegee operation in one direction by the squeegee head 13. That is, as shown in FIG. 1, the clamper 7A is set to have a width dimension that includes the position directly below the squeegee 16A, which is the leading side squeegee, in the contact range with the mask plate 12.

Next, referring to FIG. 2, a squeegee lifting mechanism 15
The height position when the squeegees 16A and 16B move up and down on the screen mask 12 by A and 15B will be described. The squeegee lifting mechanisms 15A, 15B have a multi-point stop position holding function, and can hold the squeegees 16A, 16B at arbitrary height positions in the operation of lifting the squeegees 16A, 16B.

FIG. 2A shows a height position during printing. In this state, the lower end portions of the squeegees 16A and 16B are pressed against the mask plate 12 with a predetermined printing pressure. Has become. FIG. 2B shows the height of the squeegee when the printing operation is stopped, that is, the standby height H0. In this state, the squeegee 16A, 1
6B is kept at a position elevated from the mask plate 12 by a sufficient height.

FIG. 2C shows the height position during non-printing. When either of the two squeegees 16A and 16B performs a squeegee operation, the squeegee that does not perform squeegee stops. The height position is shown. That is,
In this state, the squeegee on the non-printing side is the mask plate 1
It is kept at a position slightly elevated from the upper surface of 2 by a height H1. By setting the height of the squeegee on the non-printing side as described above, there is an advantage that the time required for the squeegee switching operation during the printing operation can be shortened, as described later.

Next, the screen printing method will be described with reference to FIGS. Here, squeegee head 1
3 shows an operation when reciprocally moving 3 on the mask plate 12 to continuously print on a plurality of substrates 6. FIG. 3A shows a state in which the squeezing operation is started for the first substrate 6 first. At this time, the squeegee head 13 is located on the left clamper 7A. The squeegee 16A on the printing side is the mask plate 1
2, the cream solder 17 is supplied to the squeegee surface of the squeegee 16A. At this time, the squeegee 16B on the non-printing side is located at a position elevated by H1 from the mask plate 12.

When the squeegee operation is started, the squeegee head 13 moves in the direction of arrow b (forward direction), whereby the cream solder 17 is printed on the substrate 6 via the mask plate 12. That is, in this forward direction printing operation, of the two squeegees 16A and 16B, the squeegee 16A on the trailing side in the squeezing direction is brought into contact with the mask plate 12, and the squeegee 16B on the leading side is separated from the mask plate 12. Then, the squeegee head 13 is moved in the forward direction (forward squeegeeing step). Then, when the squeegee head 13 moves to reach the clamper 7B as shown in FIG. 3B, Printing on the first substrate 6 is completed. Then, the plate 6 is separated from the mask plate 12 to separate it from the mask plate 12, and then a new substrate 6 is replaced.

Next, as shown in FIG. 3C, squeegee switching is performed. That is, after the squeegee head 13 reaches the movement end point, the leading side squeegee 16B (the printing side squeegee in the next squeegee operation) is lowered and brought into contact with the mask plate 12, and after the squeegee is completed in the previous squeegee operation. Raise the row-side squeegee 16A by a height H1 to raise the mask plate 1
Separate from 2 (squeegee switching process). In this squeegee switching, the descending operation of the leading side squeegee 16B and the ascending operation of the trailing side squeegee 16A are not limited, and either operation may be performed first or two operations may be performed simultaneously. Good.

Then, as shown in FIG. 4 (a), the squeegee head 13 moves in the direction of arrow c to print on the second substrate 6. At this time, the squeegee 16B has the squeegee 16B in the previous squeegee operation.
The cream solder 17 scraped by A is scraped in the opposite direction. The squeegee 16A moves while dragging the cream solder 17 attached on the previous printing on the mask plate 12.

In FIG. 4 (b), the squeegee head 13 reaches the clamper 7A in this way, and the second substrate 6
It shows a state in which printing for is completed. At this time,
The squeegee 16A has a slight amount of cream solder 17 at the lower end.
Is still attached. Then, in this state, the same squeegee switching as described above is repeatedly performed.

As described above, in the squeegee switching step which is repeatedly performed every time when the moving direction of the squeegee head is reversed, in the screen printing method of the present embodiment, the squeegee on the preceding side is squeezed in the next squeegee operation. An operation pattern is used in which the mask plate 12 is brought into contact with the mask plate 12 without horizontally moving in the direction. This prevents the cream solder 17 attached to the lower end of the leading side squeegee from wrapping around to the back side of the squeegee surface.

That is, as shown in FIG. 4 (c), even if the cream solder 17 is attached to the lower end of the squeegee 16A, the squeegee 16A can be moved down to the right position without being moved to the right. As a result, the phenomenon that the cream solder 17 wraps around the back side of the squeegee 16A does not occur.

Therefore, the cream solder 17 wrapping around the back surface of the squeegee surface is not scratched in the squeegee operation and is outside the printing range of the mask plate 12.
Failure due to remaining in the state of being adhered to the surface, that is, a decrease in yield due to wasteful adhesion of the cream solder 17 outside the printing range, and an excessively dried cream that has been left in such an adhesion state for a long time. It is possible to prevent problems such as deterioration of print quality due to the mixture of the solder 17. At this time, the position directly below the squeegee 16A is within the range where the clampers 7A and 7B contact the lower surface of the mask plate 12 and the mask plate 12 is received under the mask plate 12, so that the mask plate 12 is not damaged.

[0028]

According to the present invention, in the squeegee switching process when reversing the squeegee direction, the leading squeegee is brought into contact with the mask plate without horizontally moving in the squeegee direction in the next squeegee operation. Therefore, it is possible to prevent the paste attached to the lower end portion of the squeegee on the leading side from wrapping around to the back side of the squeegee surface to enable high-speed printing, and to prevent waste of the paste and deterioration of quality.

[Brief description of drawings]

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

FIG. 2 is a partial sectional view of an embodiment of the present invention.

FIG. 3 is a process explanatory diagram of a screen printing method according to an embodiment of the present invention.

FIG. 4 is a process explanatory diagram of a screen printing method according to an embodiment of the present invention.

[Explanation of symbols]

1 Screen printing device 3 Board positioning part 5 Substrate holder 6 substrate 7A, 7B clamper 12 Mask plate 13 Squeegee head 15A, 15B lifting mechanism 16A, 16B squeegee 17 cream solder 20 means of transportation

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takahiro Fukagawa             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Ryo Maeda             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 2C035 AA06 FD19 FD37 FD42                 5E319 AA03 AC01 BB05 CD29 GG03                 5E343 AA02 BB72 DD05 FF04 GG11

Claims (2)

[Claims] 1. A screen for printing a paste on a substrate through the pattern hole by bringing a mask plate provided with a pattern hole into contact with the substrate, supplying the paste onto the mask plate and sliding a squeegee. A printing apparatus comprising: a clamp member that clamps both end faces of the substrate in the squeegee direction and abuts against the lower surface of the mask plate; and two squeegees arranged for squeegee operations in the forward and reverse directions. A squeegee head, moving means for reciprocating the squeegee head in the squeegee direction, and elevating means for individually elevating and lowering the squeegee on the mask plate. Mask play the position directly below the squeegee on the leading side when the squeegee head reaches the moving end point. Screen printing apparatus characterized by and has a size including the contact range with. 2. A mask plate provided with a pattern hole is brought into contact with a substrate, a paste is supplied onto the mask plate, and the mask plate is arranged for squeezing operation in two directions.
By moving the squeegee head with two squeegees on this mask plate and sliding the squeegee,
A screen printing method for printing paste on a substrate through the pattern holes, wherein a squeegee on a trailing side in the squeegee direction of the two squeegees is brought into contact with a mask plate and a squeegee on a leading side is separated from the mask plate. A forward squeegee step of moving the squeegee head in the forward direction to perform a squeegee operation;
Of the two squeegees, the squeegee on the trailing side with respect to the squeegee direction is brought into contact with the mask plate and the squeegee on the leading side is separated from the mask plate to perform a squeegeeing operation in the opposite direction, and In the process of repeating the forward squeegee process and the reverse process squeegee process, after the squeegee head reaches the moving end point, the leading side squeegee is lowered with respect to the mask plate and the trailing side squeegee is separated from the mask plate. In the squeegee switching step, the squeegee switching step is performed by contacting the leading side squeegee with the mask plate without horizontally moving in the squeegeeing direction in the next squeegee operation to attach to the lower end of the leading side squeegee. To the back of the squeezed surface of the paste Screen printing method characterized by preventing sneak.