WO2024075268A1

WO2024075268A1 - Squeegee device

Info

Publication number: WO2024075268A1
Application number: PCT/JP2022/037578
Authority: WO
Inventors: 松崎直樹
Original assignee: 株式会社Fuji
Priority date: 2022-10-07
Filing date: 2022-10-07
Publication date: 2024-04-11

Abstract

A squeegee device provided with paste doctors that prevent lateral leakage of cream solder, the squeegee device comprising: a travel mechanism that reciprocates a traveling mount; two raising/lowering machines assembled to the traveling mount; and a pair of squeegee heads assembled to lower ends of the two raising/lowering machines and provided with squeegee blades that roll the cream solder on a mask, the squeegee heads each being equipped with paste doctors which are board members for preventing lateral leakage of the cream solder through the squeegee blade, are attached to both ends of a base bar supporting the squeegee blade, and can shift vertically in a state of being pressed down by spring members.

Description

Squeegee Device

The present invention relates to a squeegee device equipped with a paste doctor that prevents sideways leakage of cream solder.

In a screen printing machine, the substrate brought in by the transport device is held and placed in the printing position under the mask, and then cream solder is printed onto the substrate from above the mask through the printing pattern (through holes) by the squeegee. During this process, the cream solder is pressed into the printing pattern as it rolls over the mask by the squeegee. Paste doctors are provided at both ends of such a squeegee head to prevent the cream solder from spilling out from the sides. Patent Document 1 below discloses a squeegee device having a paste doctor as shown in Figure 7. Figure 7 is a perspective view showing the end of a squeegee head equipped with a conventional paste doctor.

A conventional paste doctor 100 is attached in a state where its position can be adjusted to a guide rail 102 that is perpendicular to the direction F, which is the traveling direction of the squeegee blade 101. The paste doctor 100 is formed from a thin metal plate, and its shape is such that the mounting portion 111 of the guide rail 102 is formed wide, from which extends a narrower band-like side leakage prevention portion 112. The side leakage prevention portion 112 is composed of a rear portion 121 that extends in the width direction and is located behind the squeegee blade 101, a side receiving portion 122 that is bent in the traveling direction, and a width adjustment portion 123 on the forward side of the traveling direction to receive a wide amount of cream solder.

JP 2001-121195 A

However, in the conventional squeegee device, the paste doctor 100 extends from the mounting portion 111 to the lateral leakage prevention portion 112 and is formed to surround the end of the squeegee blade 101. This results in the end of the squeegee device becoming larger, and a space is required on the mask side to prevent interference with the paste doctor 100. Furthermore, although the conventional paste doctor 100 can be adjusted in the width direction along the guide rail 102, it cannot be adjusted in the vertical direction in which printing pressure is applied, and therefore is not able to follow the deflection of the squeegee blade 101. This can result in a gap being generated between the paste doctor 100 and the mask, etc., which can cause cream solder to leak.

The present invention aims to solve this problem by providing a squeegee device equipped with a paste doctor that prevents the cream solder from leaking sideways.

The squeegee device in one aspect of the present invention has a traveling mechanism that moves a traveling platform back and forth, two elevators attached to the traveling platform, and a pair of squeegee heads attached to the lower ends of the two elevators and equipped with squeegee blades that roll the cream solder on the mask. The squeegee heads are plate members that prevent the cream solder from leaking sideways from the squeegee blades, and are attached to both ends of a base bar that supports the squeegee blades, and have paste doctors attached that can be displaced up and down while being pressed from above by spring members.

In this configuration, the travel mechanism moves the travel platform, and when one of the two elevators descends, the squeegee blade of the squeegee head attached to its lower end rolls the cream solder on the mask. The squeegee head is held down from above by a spring member and the paste doctor, which is capable of moving up and down, moves in contact with the mask, preventing the cream solder from leaking sideways from the squeegee blade.

FIG. 2 is a perspective view showing a squeegee device in a screen printing machine, partially in cross section. FIG. 1 is a perspective view showing an embodiment of a squeegee device. FIG. 2 is a side view of the end of the squeegee head in the X-axis direction, showing the paste doctor from the outside and inside in particular. 2 is an enlarged view showing an end portion of the squeegee head surrounded by a circle B in FIG. 1 . 1A to 1C are three views showing an embodiment of a paste doctor. 2 is an enlarged view showing an end of a squeegee head on a collection plate surrounded by a circle B in FIG. 1 . FIG. 1 is a perspective view showing the end of a squeegee head equipped with a conventional paste doctor.

One embodiment of the squeegee device according to the present invention will be described below with reference to the drawings. The squeegee device of this embodiment is incorporated into a screen printing machine. Figure 1 is a perspective view showing a partial cross section of the squeegee device inside the screen printing machine, and Figure 2 is a perspective view showing the squeegee device.

First, the screen printer is configured to perform a pre-processing step of the component execution machine, which mounts electronic components on the printed circuit board 10. In the screen printer, the printed circuit board 10, which has been brought in by the board transport device, is placed under the mask 20, and the cream solder on the mask 20 is rolled by the squeegee device 1. As a result, the cream solder is spread so as to be forced into the pattern holes formed in the mask 20, and a predetermined pattern is printed on the printed circuit board 10 using the cream solder.

The squeegee device 1 of such a screen printing machine has a rod-shaped running platform 2 that is long in the width direction of the machine body (X-axis direction), and is configured with a running mechanism that can move back and forth in the front-to-rear direction of the screen printing machine body (Y-axis direction). Specifically, slide guides 11 are fixed to both ends of the running platform 2 and are attached so as to be able to slide freely on guide rods installed in the Y-axis direction inside the machine. Note that in this embodiment, the width direction of the screen printing machine will be described as the X-axis, the front-to-rear direction as the Y-axis, and the up-down direction as the Z-axis.

A nut 12 that constitutes a ball screw mechanism is fixed to the running platform 2, and a screw shaft passes through the nut 12 in the Y-axis direction. Thus, in the squeegee device 1, a servo motor is connected to the screw shaft, which is freely rotatable by a bearing, and the squeegee device 1 can be moved to a predetermined position in the fore-aft direction of the machine body by controlling the servo motor. The squeegee device 1 has two elevators attached to the center of the running platform 2, which is long in the width direction, and is covered by a cover 6.

Paired squeegee heads

3, 4 are attached to the lower ends of the two elevators, and each can be raised and lowered independently.

The

squeegee heads

3 and 4 are configured symmetrically in the front-to-rear direction. Squeegee head 3 is for rolling the cream solder in one direction in the Y-axis direction, and the other squeegee head 4 is for rolling the cream solder in the opposite direction. Squeegee head 3 (hereinafter, the same applies to squeegee head 4 unless otherwise specified) has a squeegee blade 15 that rolls the cream solder placed on mask 20 onto mask 20. The paste-like cream solder is supplied linearly in the width direction onto mask 20, and squeegee blade 15 moves the cream solder in the front-to-rear direction while pressing it against mask 20.

Here, FIG. 3 is a diagram showing the end of the squeegee head 3 enclosed by the circular frame A in FIG. 2 in the X-axis direction, and in particular shows the paste doctor from the outside and inside. The squeegee head 3 has a squeegee blade 15 fixed to a rod-shaped base bar 13 that corresponds to the width dimension of the mask 20. The squeegee blade 15 is a thin, band-shaped metal plate, and the squeegee head 3 is fixed so that the squeegee blade 15 is inclined relative to the base bar 13. The squeegee blade 15 is abutted against the inclined surface 131 of the base bar 13 and screwed at its upper end, and a cover member 14 is placed over the upper end. Therefore, the squeegee blade 15 is attached so that the lower end side that contacts the mask 20 is inclined backward with respect to the traveling direction Y1.

The squeegee head 3 equipped with the squeegee blade 15 can be attached to and detached from the elevator. A mounting block 18 is fixed to the top surface of the base bar 13 at two points, and a fastening bolt 19 is screwed into the top surface of the mounting block 18. A support section 21 with a U-groove cut out is formed on the elevator side, and by tightening the fastening bolt 19 with a threaded portion passing through it, the squeegee head 3 is attached by sandwiching the support section 21 between the bolt head and the mounting block 18 from above and below.

The squeegee device 1 rolls the squeegee blade 15 in contact with the mask 20 as it moves in the direction of travel Y1, pressing the cream solder in front of it against the mask 20. At this time, it is necessary to prevent the cream solder from leaking sideways from the end of the squeegee blade 15, so paste doctors 17 are attached to both ends of the base bar 13 so as to sandwich the squeegee blade 15.

Here, Fig. 4 is an enlarged view showing the ends of the

squeegee heads

3, 4 enclosed in a circular frame B in Fig. 1. Also, Fig. 5 is a three-view diagram showing the paste doctor 17. As shown in the front view of Fig. 5, the paste doctor 17 has two vertical long holes 71 formed therein, and is attached to the end of the base bar 13 by bolts 23 that pass through the long holes 71. Therefore, the paste doctor 17 can move up and down relative to the base bar 13, but the upper end surface is pressed down by a leaf spring 25 that is screwed to the top surface of the base bar 13.

The paste doctor 17 is a roughly rectangular plate member as seen in the front view of Figure 5, and has an inclined portion 73 formed on the front side portion that spreads outward in the width direction of the machine. For example, consider a case where the cream solder rolled by the squeegee head 4 is rolled in the opposite direction by the squeegee head 3. When the squeegee head 4 rises to the stopped position, as shown in Figure 4, the viscous cream solder 80 is lifted by the paste doctor 17 which is moving away from the mask 20, and after it is separated, it spreads outward as shown by the arrow. The inclined portion 73 that spreads outward in the width direction is shaped to collect the cream solder that spreads outward from the squeegee blade 15 when the squeegee head 3 rolls the cream solder 80.

The paste doctor 17 has a front taper 75 formed at the lower corner of the inclined portion 73 provided at the front of the traveling direction Y1. A recovery plate 55 is placed at the stopping position where the cream solder is rolled so that the paste doctor 17 can ride up smoothly there. As shown in Figure 1, the screen printing machine is provided with recovery devices 50 at two locations, the front and rear ends of the printed circuit board 10, and the recovery plate 55 made of tapered plate material is configured to be able to rise and fall. Therefore, the cream solder rolled by the squeegee head 3 on the mask 20 is placed on the recovery plate 55 on the traveling direction Y1 side.

Here, Figure 6 is an enlarged view showing the ends of the squeegee heads 3, 4 on the recovery plate 55 enclosed in a circular frame B in Figure 1. The paste doctor 17 has a rear tapered portion 77 formed at the bottom corner opposite the traveling direction Y1. This shape is designed to prevent the cream solder adhering to the paste doctor 17 from dropping to the rear. In other words, in order to efficiently use the cream solder on the recovery plate 55, the squeegee head 3 first shifts its position rearward and then moves in the traveling direction Y1. At that time, this is to prevent the rear side of the paste doctor 17 with the cream solder attached from protruding rearward from the recovery plate 55.

When the squeegee head 3 descends for printing, the squeegee blade 15, to which printing pressure is applied, bends at its lower end. As described above, the paste doctor 17 can be displaced up and down. Therefore, when the paste doctor 17 comes into contact with the collection plate 55 or the mask 20, it receives a reaction force and displaces upward. In other words, the squeegee head 3 is configured so that the paste doctor 17 is always in contact with the collection plate 55 or the mask 20 during printing due to the biasing force of the leaf spring 25, preventing the cream solder from leaking sideways. In this regard, the conventional paste doctor 100 shown in Figure 7 has no freedom in the vertical direction.

On the other hand, the conventional paste doctor 100 has a rear portion 121, so that it can receive cream solder even on the rear side of the squeegee blade 101. However, because the paste doctor 100 has a structure that protrudes to the rear, it is not suitable for narrow spaces on the mask. Therefore, in this embodiment, a small plate-shaped paste doctor 17 is attached to the end face of the base bar 13.

The squeegee head 3 has a small gap between the squeegee blade 15 and the paste doctor 17, which causes the cream solder to leak to the rear. However, the paste doctor 17 to which the cream solder adheres is shaped with a rear tapered section 77, so that when the squeegee head 3 retracts above the collection plate 55 as described above, the adhered cream solder does not spill out and fall off the collection plate 55. In addition, a chamfered section 79 is formed on the outside of the lower end of the paste doctor 17, reducing the thickness downward, so that the adhered cream solder can be easily cut off.

In the squeegee device 1 configured as above, the squeegee head 4 is lowered by, for example, the lowering operation of the elevator, and moves to the left side as shown in FIG. 1, causing the cream solder to roll on the mask 20 while being pressed by the squeegee blade 15. The cream solder is then placed on the collection plate 55 above the printed circuit board 10. At this time, the paste doctor 17 that rides onto the collection plate 55 rises against the elastic force of the leaf spring 25, and the inclined portion 73 formed on the traveling direction side ensures smooth movement.

When the printing process in one direction by the squeegee head 4 is completed, the cream solder on the collection plate 55 is printed again by the squeegee head 3 on the opposite side. That is, while the squeegee head 4 rises, the squeegee head 3 on the opposite side moves back slightly in the direction of travel Y1 and then lowers. The squeegee blade 15 and paste doctor 17 come into contact with the collection plate 55, and the inclined portion 73 moves in the direction of travel Y1 while collecting the cream solder at the end where it has spread. The cream solder that has rolled over the mask 20 in the same way then passes over the printed circuit board 10 and is placed on the collection plate 55 on the opposite side.

As described above, according to the squeegee device 1 of this embodiment, the paste doctor 17 is constructed from a plate member attached to the end of the base bar 13, making it possible to make it compact. The paste doctor 17 is pressed down by the leaf spring 25 in a state in which it can be displaced up and down, so that it is always in contact with the mask 20 and the recovery plate 55, effectively preventing the cream solder from leaking out sideways.

When the paste doctor 17 moves in contact with the mask 20 and is transferred to the collection plate 55, the front tapered portion 75 allows it to ride up smoothly. This makes it less likely for the cream solder being transported to leak sideways from the paste doctor 17 than before. Even if some cream solder does leak sideways, it is collected by the inclined portion 73 on the

squeegee head

3 or 4 on the opposite side. Because the squeegee device 1 is configured to be compact as described above, the width of the collection plate 55 can also be narrowed, and the rear tapered portion 77 prevents the cream solder adhering to the paste doctor 17 from spilling out and falling off the collection plate 55.

Although one embodiment of the present invention has been described, the present invention is not limited to this, and various modifications are possible without departing from the spirit of the invention.

REFERENCE SIGNS LIST 1 squeegee device 2

running platform

3, 4 squeegee head 13 base bar 15 squeegee blade 17 paste doctor 10 printed circuit board 20 mask 55 collection plate 71 long hole 73 inclined portion 75 front tapered portion 77 rear tapered portion 79 chamfered portion

Claims

A traveling mechanism for reciprocating the traveling platform;
Two elevators mounted on the running platform;
a pair of squeegee heads attached to the lower ends of the two elevators and equipped with squeegee blades for rolling the cream solder on the mask;
The squeegee head is a plate member that prevents cream solder from leaking sideways from the squeegee blade, and is attached to both ends of a base bar that supports the squeegee blade.The squeegee device has a paste doctor attached to it that can be displaced up and down while being pressed down from above by a spring member.
The squeegee device according to claim 1, in which the paste doctor is attached to the end of the base bar by a bolt passing through a vertical long hole, and the upper end surface is pressed down by a leaf spring screwed to the upper surface of the base bar.
The squeegee device according to claim 1 or 2, wherein the paste doctor has an inclined portion formed on the front side in the direction of travel that widens outward, and a front tapered portion formed on the lower corner of the inclined portion.
The squeegee device according to claim 1 or 2, wherein the paste doctor has a rear tapered portion formed at the bottom corner on the rear side in the direction of travel.
5. The squeegee device according to claim 4, wherein the paste doctor has a chamfered portion formed on the outer side of a lower end portion thereof, the chamfered portion being such that the thickness of the paste doctor decreases downward.