WO2019234791A1

WO2019234791A1 - Screen printing machine

Info

Publication number: WO2019234791A1
Application number: PCT/JP2018/021355
Authority: WO
Inventors: 深草祥史
Original assignee: 株式会社Ｆｕｊｉ
Priority date: 2018-06-04
Filing date: 2018-06-04
Publication date: 2019-12-12
Also published as: JPWO2019234791A1; JP7002181B2; CN112218761B; EP3804991A4; EP3804991B1; EP3804991A1; CN112218761A

Abstract

A screen printing machine comprising: a mask holding device that holds a mask; a squeegee device that applies and spreads cream soldier onto the mask being held by the mask holding device from above; a conveyance device that conveys a substrate under the mask; a substrate holding and elevating device that holds the substrate conveyed by the conveyance device and positions the substrate in a vertical direction with respect to the mask; a cleaning device that wipes off and cleans a lower surface of the mask; an imaging device that images a reference mark of the mask and a reference mark of the substrate; a driving device that causes the imaging device and the cleaning device to be moved between the mask and the substrate holding and elevating device; and a control device that controls the respective devices and causes, with respect to the substrate holding and elevating device, an elevating part thereof to be set at a reference height corresponding to the size of the imaging device, and to be lowered from the reference height in accordance with the size of the cleaning device when the cleaning device is moved.

Description

Screen printing machine

The present invention relates to a screen printing machine in which the normal height of the substrate is higher than the position at the time of mask cleaning.

The screen printer is equipped with a mask having a pattern hole formed thereon, and the substrate transported below is held. Then, the substrate rises and comes into contact with the lower surface of the mask, and the cream solder is spread from the upper surface side of the opposite mask by the squeegee device, whereby the cream solder passing through the pattern holes is printed on the substrate. In such a screen printer, as shown in the following Patent Document 1, a camera unit (imaging device) enters between a mask and a substrate positioned below the mask, and a reference mark attached to the lower surface of the mask. The reference marks attached to the upper surface of the substrate are imaged sequentially. Then, the position of each reference mark is confirmed by image processing, and correction is performed when there is a deviation.

Also, the screen printing machine is provided with a cleaning unit (cleaning device) that wipes off the dirt on the mask. The cleaning unit is configured to be able to move between the mask and the substrate, like the camera unit. In particular, in this conventional example, a coupling mechanism is provided so that the cleaning unit and the camera unit can be attached and detached. Both units are moved by the drive unit provided on the camera unit side. Normally, the cleaning unit is separated from the camera unit and only the camera unit can be moved. When cleaning the mask, it is connected to the camera unit. As a result, the cleaning unit can be moved.

Japanese Patent Laying-Open No. 2015-80870

By the way, the cleaning unit provided in the screen printer has a structurally larger height dimension than the camera unit, such as a roll-shaped cleaning paper and a cylinder for pressing the cleaning paper against the lower surface of the mask. End up. Therefore, in order to secure a space for the cleaning unit to enter, it is necessary to widen the distance between the mask and the substrate, and the conventional screen printing machine has a long ascending / descending distance for moving the substrate to the mask during printing. . Therefore, the conventional screen printing machine has a problem that the cycle time becomes longer according to the lift distance of the substrate. In addition, since the movement distance of the substrate is long, a slight error in the movement direction increases the amount of deviation between the substrate and the mask, resulting in a decrease in printing accuracy.

Therefore, an object of the present invention is to provide a screen printing machine that makes the position of the substrate correspond to the height dimension of the imaging device in order to solve such a problem.

A screen printing machine according to an aspect of the present invention includes a mask holding device that holds a mask, a squeegee device that spreads cream solder on the mask held by the mask holding device from above, and a substrate under the mask. A transport device that transports the substrate, a substrate holding and lifting device that holds the substrate transported by the transport device and performs vertical positioning with respect to the mask, a cleaning device that wipes and cleans the lower surface of the mask, and a reference mark for the mask And an image pickup device for picking up an image of the reference mark on the substrate, a drive device for moving the image pickup device and the cleaning device between the mask and the substrate holding lift device, and controlling each device. The lifting / lowering portion of the substrate holding lifting / lowering device is set to a reference height corresponding to the size of the imaging device. Constant and, upon movement of the cleaning device and a control device for lowering from the reference height in accordance with the size of the cleaning device.

According to the above configuration, after the substrate is transferred by the transfer device to the lower side of the mask held by the mask holding device, the substrate is held by the substrate holding lifting device and positioned so as to be in contact with the lower surface of the mask. The Then, cream solder is spread from above the mask by a squeegee device, and printing on the substrate is performed. In addition, during such substrate printing, the imaging device enters between the mask and the substrate by the driving device, and the reference mark is imaged. After a predetermined number of printing processes, the cleaning device enters and the lower surface of the mask Wiping and cleaning are performed. The substrate holding and lifting device is set at a reference height corresponding to the size of the imaging device during normal printing, so that the held substrate is placed at a distance close to the mask and when cleaning the mask. As the elevating unit descends, interference with the cleaning device is avoided.

It is the side view which simplified and showed the internal structure of the screen printer. It is the figure which simplified and showed the structure of the board | substrate holding | maintenance raising / lowering apparatus of a screen printer. It is the figure which simplified and showed the movement periphery of a camera unit and a cleaning unit. It is the figure which showed the height of the board | substrate at the normal time. It is the figure which showed the height of the board | substrate at the time of the cleaning which a cleaning unit moves. It is the figure which showed notionally the positional relationship of a board | substrate, a mask, and a camera unit.

Next, an embodiment of a screen printer according to the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing a simplified internal structure of a screen printing machine. This screen printing machine 1 is for printing cream solder on a substrate, and constitutes a circuit board production line together with, for example, an inspection machine for inspecting the printing state and a component mounting machine for mounting electronic components on a substrate. It is. In the present embodiment, the front-and-rear direction of the screen printing machine 1 shown in the drawing will be described as the Y-axis direction, the body width direction as the X-axis direction, and the body height direction as the Z-axis direction.

In the screen printing machine 1, a mask is arranged inside the machine body, a substrate is conveyed and held under the mask, and cream solder is applied to the substrate on the lower side from the upper surface of the mask through the printing pattern hole. Therefore, the screen printing machine 1 has a mask holder 2 on the upper side so that a mask can be attached. A squeegee device 3 for spreading the cream solder on the mask in the longitudinal direction of the machine body is installed on the upper side of the mask holder 2. On the other hand, on the lower side of the mask holder 2 is provided a substrate holding elevating device 4 that holds the transferred substrate and moves it in the vertical direction.

The screen printing machine 1 is covered with a machine body cover 19 as shown in the figure, but a transport port 191 is formed on both side surfaces in the machine body width direction so that substrates can be carried in and out. Therefore, a substrate transport device for transporting the substrate in the body width direction is provided below the mask holder 2. Further, on the lower side of the mask holder 2, a clamping device for clamping the substrate in the longitudinal direction of the machine body, a backup device for moving the substrate up and down to the clamping position, and the like are assembled in the lifting device. In the present embodiment, the clamping device and the lifting device are collectively referred to as a substrate holding lifting device 4. FIG. 2 is a diagram showing a simplified structure of the substrate holding / lifting device 4 of the screen printing machine 1.

First, in the lifting device 8, a lifting platform 12 is slidably attached to a guide rail 11 in a vertical direction, and the lifting platform 12 is connected to a lifting motor 14 via a ball screw 13. A substrate transfer device 5, a clamp device 6, and the like are mounted on the lifting platform 12 via a support table 15. A pair of mask supports 21 are provided on the support base 15 in the longitudinal direction of the machine body (Y-axis direction), and mask support plates 28 that contact the mask 20 are fixed to the upper surfaces of the legs. A ball screw 22 is formed on the mask support 21 on the right side of the drawing, and the distance from the mask support 21 on the left side of the drawing can be adjusted by a mask support motor.

The clamp device 6 has a pair of side frames 25 arranged in the longitudinal direction of the machine body, and is assembled to the support base 23, respectively. A ball screw 26 is formed on the side frame 25 on the right side of the drawing, and the distance from the side frame 25 on the left side of the drawing can be adjusted by a substrate clamping motor. The pair of side frames 25 has a clamp portion 27 formed at the upper end thereof, and the clamp portions 27 come close to each other so that the substrate 10 can be held therebetween. A substrate transfer device 5 including a conveyor belt 29 is assembled inside the side frame 25.

A backup device 7 that supports the substrate 10 is provided between the pair of side frames 25. The backup device 7 is configured such that a backup table 31 having a plurality of backup pins 32 is supported via a ball screw and is moved up and down by a backup motor 34. Further, the support base 23 of the clamp device 6 is supported via a ball screw and is configured to be moved up and down by a lifting motor 33. The support table 15 that supports the clamp device 6 and the backup device 7 can be adjusted in position in the X direction, the Y direction, and the θ direction on the XY plane with respect to the lifting table 12. That is, a correction device that adjusts the position of the held substrate 10 and the mask 20 is configured.

In this way, the screen printing machine 1 includes the substrate holding and lifting device 4 in which the clamping device 6 and the backup device 7 are assembled to the lifting device 8 on the lower side of the mask 20, and the height of the substrate 10 is increased stepwise. It is configured to change. In particular, in the present embodiment, the position of the lifting platform 12 shown in FIG. 2 is configured as the reference height K. This reference height K specifies the transport height of the substrate 10 transported by the substrate transport device 5. Is. That is, when the lifting platform 12 is positioned at the reference height and the clamp device 6 and the backup device 7 are lowered as shown in FIG. 2, the substrate transfer device 5 assembled to the clamp device 6 becomes the transfer position.

The conveyor belt 29 which comprises the board | substrate conveying apparatus 5 is assembled | attached to the clamp apparatus 6 in the position lower than the clamp part 27. As shown in FIG. Accordingly, the transferred substrate 10 is configured to move upward by the backup device 7 in order to align the upper surface with the clamp portion 27. After printing, it moves downward, but the height of the upper surface of the conveyor belt 29 is such that the thickness of the substrate 10 that can be processed by the screen printing machine 1 and the amount of warpage so that the vertical movement distance becomes smaller. It is set by.

Further, the clamp device 6 is configured such that the held substrate 10 moves upward so that the upper surface of the substrate 10 is aligned with the mask support plate 28. After printing, it moves downward, but in this case as well, the upper surface height of the clamp portion 27 with respect to the mask support plate 28 is set in the clamping device 6 so that the moving distance in the vertical direction becomes small. . Therefore, in the substrate holding / lifting device 4, the relationship of the height of each member is set, and the height of the upper surface of the conveyor belt 29 relative to the upper surface of the mask support plate 28 is also a predetermined height.

Next, between the mask holder 2 and the substrate holding / lifting device 4, as shown in FIG. 3, a camera unit 35 (imaging device) and the mask 20 are used to image the reference marks attached to the substrate 10 and the mask 20. A cleaning unit 37 (cleaning device) is provided for cleaning the surface by wiping off dirt from the lower surface side. FIG. 3 is a diagram showing the movement periphery of the camera unit 35 and the cleaning unit 37 in a simplified manner. In particular, the camera unit 35 and the cleaning unit 37 are separated, and only the camera unit 35 enters between the substrate 10 and the mask 20. In the screen printing machine 1 shown in FIG. 1, the arrow A <b> 1 is the movement range of the camera unit 35 and the cleaning unit 37, and the arrow A <b> 2 is the movement range of the substrate 10.

The camera unit 35 and the cleaning unit 37 are slidably attached to a guide rod 41 extending in the longitudinal direction of the machine body and configured to be movable by a driving device. The drive device of the present embodiment is configured so that only the camera unit 35 can self-propell like the conventional example. In the drive device, for example, a screw shaft that is rotated by a drive motor is provided in parallel with the guide rail 41, and a nut fixed on the camera unit 35 side is screwed to form a ball screw. In order to allow the cleaning unit 37 to move by being connected to a self-running camera unit 35, a coupler is formed in both units.

First, the cleaning unit 37 is configured such that a roll-shaped cleaning paper is used, and the used portion that is unwound from the first roller 43 before use and wiped off the mask 20 is wound around the second roller 44. Yes. The cleaning paper 13 is wound (unwinding from the first roller 43) by a servo motor provided on the second roller 44 side, and the cleaning paper is pressed against the lower surface of the mask 20 between the two rollers. A paper pressing mechanism using an air cylinder 45 is incorporated. On the other hand, the camera unit 35 has a prism combined with the camera 47 in order to image both the upper mask and the lower substrate.

In the camera unit 35, a solenoid 48 for moving the plunger up and down is provided. A through hole is formed in the cleaning unit 37, and a connecting plate 49 projects toward the camera unit 35. The solenoid 48 and the connection plate 49 serve as a connector for connecting the camera unit 35 and the cleaning unit 37. Therefore, when the plunger of the solenoid 48 extends downward and is inserted into the through hole of the connecting plate 49 inserted into the camera unit 35, the cleaning unit 37 is connected to the camera unit 35 and can be moved integrally. .

In the cleaning unit 37, as shown in FIG. 1, the front portion of the screen printing machine 1 is in a standby position. Therefore, when the mask 20 is cleaned using the cleaning unit 37, the camera unit 35 moves to the standby position and is connected to the cleaning unit 37. On the other hand, in a state where the plunger of the solenoid 48 is pulled up, the camera unit 35 and the cleaning unit 37 are separated so that the reference mark attached to the substrate 10 or the mask 20 is imaged by the movement of the camera unit 35 alone. It has become.

Incidentally, the camera unit 35 and the cleaning unit 37 are entirely covered with a unit cover, but the height dimension of the cleaning unit 37 is larger than the height dimension of the camera unit 35. This is because a roll-shaped cleaning paper wound around the first and

second rollers

43 and 44 and an air cylinder 45 for pressing the cleaning paper against the mask are incorporated. In this regard, in the conventional screen printing machine, the distance between the substrate 10 and the mask 20 is designed corresponding to the height of the cleaning unit 37 having a large size. For this reason, the moving distance of the substrate 10 becomes longer, the cycle time becomes longer, and the positional accuracy of the substrate 10 with respect to the mask 20 is lowered.

Therefore, the screen printer 1 is configured such that the height of the substrate 10 is switched between the normal time shown in FIG. 4 and the cleaning time shown in FIG. The normal cleaning unit 37 is disposed at the standby position shown in FIG. 1, and only the camera unit 35 enters between the substrate 10 and the mask 20. In the present embodiment, the transport height of the substrate 10 transported into the screen printer 1 is set with the upper surface of the mask support plate 28 shown in FIG. 4 as the reference height k2. In the substrate holding / lifting device 4 in which the substrate transfer device 5 and the like are mounted on the lifting / lowering device 8, there is a possibility that the lifting / lowering unit that is displaced in the vertical direction may interfere with the camera unit 35 and the cleaning unit 37 that enter the lower side of the mask 20. . For this reason, in the present embodiment, the upper surface of the support plate 28 closest to the mask 20 in such an elevation unit is set to the reference height k2. The reference height k2 is the upper surface height of the mask support plate 28 when the lifting platform 12 is positioned at the reference height K as shown in FIG.

Here, FIG. 6 is a diagram conceptually showing the positional relationship between the substrate 10 positioned at the reference height k2, the mask 20 held by the mask holder 2, and the camera unit 35. For example, in the camera unit 35, the distance L2 from the mask 20 is set to 3 mm. Therefore, the reference height k2 is designed so that the distance L1 from the camera unit 35 to the substrate 10 is 5 mm, that is, almost the same between the distances L1 and L2. Originally, the distance L3 between the substrate 10 and the mask 20 can be minimized by setting the distances L1 and L2 to the same value, but the same degree considering the amount of state change such as warpage that may occur in the substrate 10. And the value of the distance L1 is slightly increased.

On the other hand, when cleaning the mask 20, as shown in FIG. 5, the cleaning unit 37 moves to the lower side of the mask 20, so that not only the camera unit 35 but also the cleaning unit 37 moves between the substrate 10 and the mask 20. It will be. The cleaning unit 37 is configured to be lowered downward from the reference height k2 so that the substrate 10 does not interfere with the camera unit 35 because the upper surface is aligned with the camera unit 35 and is larger downward. . Since the substrate 10 is not necessarily held when the mask 20 is cleaned, the space between the substrate 10 and the mask 20 is between the height of the substrate 10 and the mask 20 when the substrate 10 is held. It means that.

Subsequently, as shown in FIG. 2, the screen printing machine 1 is equipped with a control device 9 that controls the overall drive, and the drive control of each device including the elevation control of the substrate 10 is performed as follows. It has become. First, for printing on the substrate 10 in the screen printing machine 1, the substrate 10 is conveyed between the side frames 25 by the conveyor belt 29. Then, the backup table 31 is raised by driving the backup motor 34, and the substrate 10 pushed up by the backup pins 32 is lifted from the conveyor belt 29. After the alignment of the substrate 10, the side frame 25 is moved by driving the substrate clamping motor, and the substrate 10 is sandwiched and held by the pair of clamp portions 27.

Next, the clamp device 6 holding the substrate 10 is raised by driving the lifting motor 33, and the clamp portion 27 and the substrate 10 are positioned at the height of the mask support plate 28. That is, the upper surface heights of the mask support plate 28, the clamp part 27, and the substrate 10 are aligned with the reference height K. Then, the camera unit 35 moves between the substrate 10 and the mask 20, and the respective reference marks are imaged. Based on the imaging data, the deviation amounts in the X, Y, and θ directions with respect to the substrate 10 and the mask 20 are detected. The positional deviation correction is performed by the correction device calculated and configured on the support base 15.

When the camera unit 35 moves and moves out of the lifting range of the substrate 10, in the substrate holding lifting device 4, the lifting platform 12 is lifted from the position of the reference height K by driving the lifting motor 14, and the substrate 10 is moved to the mask 20. Positioned at a height that touches the lower surface. Then, the cream solder on the mask 20 is rolled by the squeegee device 3, pushed into the printed pattern holes, and applied to the lower substrate 10. After that, the plate 10 is moved down at a predetermined speed by driving the lifting motor 33, and printing with cream solder according to the printing pattern is performed on the substrate 10.

When printing is performed on the substrate 10, the lifting platform 12 is lowered by the driving of the lifting motor 14 and returned to the position of the reference height K. Thereafter, the clamp device 6 holding the substrate 10 is lowered by driving the lifting motor 33, the backup table 31 is lowered by driving the backup motor 34, and the substrate 10 placed on the backup pins 32 is returned to the conveyor belt 29. It is. Thus, the positions of the clamping device 6 and the backup device 7 return to the substrate conveyance height shown in FIG. 2, so that the substrate 10 can be conveyed by the substrate conveyance device 5, and the printed substrate 10 can be transferred from the screen printer 1. Unloaded and a new substrate 10 is loaded.

In the screen printer 1, as described above, the printing process for the substrate 10 and the loading / conveying of the substrate 10 are repeatedly performed, and the cleaning of the mask 20 is performed for each printing process on a predetermined number of substrates 10. At the time of the mask cleaning, the camera unit 35 moves to the cleaning unit 37 at the standby position as shown in FIG. That is, the connecting plate 4 on the cleaning unit 37 side is inserted into the camera unit 35, and the plunger of the solenoid 48 is inserted into the through hole.

On the other hand, in the substrate holding elevating device 4, the elevating table 12 is lowered by driving the elevating motor 14 so that the substrate 10, the mask support plate 28, and the like do not interfere with the cleaning unit 37, and are lowered by a predetermined distance from the reference height K. Evacuate to. The retracted position is below the substrate transport height. Therefore, the cleaning unit 37 can enter between the substrate 10 and the mask 20, and the cleaning paper is pressed against the lower surface of the mask 20 to wipe off the dirt. After the cleaning of the mask 20 is completed, the cleaning unit 37 is returned to the standby position again, and the connection with the camera unit 35 is disconnected. In the substrate holding / elevating device 4, the elevating table 12 is raised by driving the elevating motor 14, and the upper surface of the mask support plate 28 is returned to the reference height Kk2.

Therefore, according to the present embodiment, since the substrate 10 is normally held and positioned at a position close to the mask 20, the ascending and descending distance to the mask 20 is shortened, and the time required for the lifting operation during printing is shortened. Is done. For example, as compared with the conventional example in which the position of the substrate 10 is made to correspond to the cleaning unit 37, in this embodiment, the position of the substrate 10 is brought closer to the mask 20 by 25 mm by making the camera unit 35 smaller in size. Therefore, the moving distance of the substrate 10 during printing is a difference of 50 mm in the reciprocation, and the cycle time can be shortened.

Also, the positional accuracy of the substrate 10 with respect to the mask 20 can be increased by reducing the moving distance of the substrate 10. The substrate 10 moves up and down in accordance with the movement of the lifting platform 12 along the guide rail 11. Although the movement direction is designed in accordance with the vertical direction, as shown in FIG. ) Will occur. For this reason, a lateral displacement B occurs between the substrate 10 and the mask 20 at a position where the substrate 10 is in contact with the mask 20. For example, if the distance L3 between the substrate 10 and the mask 20 is 125 mm in this embodiment and 150 mm in the conventional example, the difference in the lateral deviation B is about 44 μm even if the value of the angle θ is 0.1 °. End up. Since printing on the substrate 10 requires accuracy of several tens of microns, this embodiment is also effective in increasing printing accuracy.

By the way, in the screen printing machine 1, the size of the cleaning unit 37 is larger than that of the camera unit 35. The cleaning unit 37 is preferably attached with cleaning paper having a large diameter in consideration of usage efficiency and the like. However, since the mask 20 is moved on the substrate holding / lifting device 4 for cleaning, in the case of the cleaning unit 37 having a large height in accordance with the cleaning paper, it does not interfere with it. It is necessary to secure a larger space.

Therefore, the present embodiment eliminates the drawback that the stroke of the lifting platform 12 becomes large during printing while increasing the usage efficiency of the cleaning unit 37. That is, the lifting stroke of the lifting platform 12 performed for each substrate 10 may be set according to the small camera unit 35 regardless of the size of the cleaning unit 37. On the other hand, when the mask 20 is cleaned, the lifting platform 12 is lowered to create a large space as in the prior art, so that the disadvantages of the cleaning unit 37 using cleaning paper with a large diameter can be eliminated.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to these, A various change is possible in the range which does not deviate from the meaning.
For example, in the above-described embodiment, the cleaning unit 37 is movable by being connected to the camera unit 35 capable of self-running. However, the cleaning unit 37 is also self-running in which the rotation output of the drive motor is converted into a straight motion by a ball screw. It is good also as a structure. Further, the drive device that causes each unit to travel may have another structure such as converting the rotation of the drive motor into a straight movement through a pulley or a belt.

Further, when the cleaning unit 37 is aligned with the upper surface of the camera unit 35, the distance L2 from the mask 20 can be minimized, but the height direction of the camera unit 35 is based on the center position in the height direction of both units. May be a structure in which the center of each is assembled so as to be higher than the center of the large cleaning unit 37 in the height direction.

DESCRIPTION OF SYMBOLS 1 ... Screen printer 2 ... Mask holder 3 ... Squeegee apparatus 4 ... Board | substrate holding | maintenance raising / lowering apparatus 5 ... Board | substrate conveyance apparatus 6 ... Clamp apparatus 7 ... Backup apparatus 8 ... Elevating apparatus 9 ... Control apparatus 10 ... Substrate 14 ... Elevating motor 20 ... Mask 27 ... Clamp 28 ... Mask support plate 35 ... Camera unit 37 ... Cleaning unit

Claims

A mask holding device for holding the mask;
A squeegee device for spreading cream solder on the mask held by the mask holding device from above;
A transfer device for transferring a substrate under the mask;
A substrate holding elevating device that holds the substrate transferred by the transfer device and performs vertical positioning with respect to the mask;
A cleaning device for wiping and cleaning the lower surface of the mask;
An imaging device for imaging the reference mark of the mask and the reference mark of the substrate;
A driving device for moving the imaging device and the cleaning device between the mask and the substrate holding elevating device;
Control each of the above devices, and set the lifting portion of the substrate holding lifting device to a reference height corresponding to the size of the imaging device, and the size of the cleaning device when the cleaning device is moved And a control device for lowering from the reference height according to
Having a screen printing machine.
The screen printing machine according to claim 1, wherein the driving device directly moves the imaging device, and the cleaning device is moved via a coupler provided between the driving device and the imaging device.
The screen printing machine according to claim 1 or 2, wherein the reference mark is imaged by the imaging device on the substrate placed at the holding height by the substrate holding lifting device.
4. The holding height of the substrate is set so that a distance from the imaging device that images a reference mark is approximately the same as a distance between the mask and the imaging device. The screen printing machine in any one of.