JPWO2019234791A1 - Screen printing machine - Google Patents

Abstract

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, a transport device that transports a substrate under the mask, and a transport device that transports the substrate. An imaging device that holds the mask and positions it in the vertical direction with respect to the mask, a cleaning device that wipes and cleans the lower surface of the mask, and a reference mark of the mask and a reference mark of the substrate. A drive device for moving the imaging device and the cleaning device between the device, the mask, and the substrate holding / elevating device, and each of the devices are controlled with respect to the substrate holding / elevating device. The elevating part is set to a reference height according to the size of the imaging device, and has a control device that lowers the elevating portion from the reference height according to the size of the cleaning device when the cleaning device is moved.

Description

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

In the screen printing machine, a mask having a pattern hole is attached, and the substrate conveyed under the mask 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 opposite upper surface side of the mask by the squeegee device, so that the cream solder that has passed through the pattern holes is printed on the substrate. In such a screen printing machine, as shown in Patent Document 1 below, a camera unit (imaging device) enters between a mask and a substrate positioned below the mask, and a reference mark is attached to the lower surface of the mask. And the reference marks attached to the upper surface of the substrate are imaged in order. Then, the position of each reference mark is confirmed by image processing, and if there is a deviation, correction is performed.

In addition, the screen printing machine is provided with a cleaning unit (cleaning device) for wiping off dirt on the mask. The cleaning unit, like the camera unit, has a configuration that allows it to move between the mask and the substrate. In particular, in this conventional example, a connecting mechanism is provided so that the cleaning unit and the camera unit can be attached to and detached from each other. It is the drive device provided on the camera unit side that moves both units. Normally, the cleaning unit is separated from the camera unit and only the camera unit can be moved, and when cleaning the mask, it is connected to the camera unit. By doing so, the cleaning unit can be moved.

Japanese Unexamined Patent Publication No. 2015-80870

By the way, the cleaning unit provided in the screen printing machine has a roll-shaped cleaning paper and a cylinder for pressing the cleaning paper against the lower surface of the mask, and the height dimension is structurally larger than that of the camera unit. It ends up. Therefore, in order to secure a space for the cleaning unit to enter, it is necessary to widen the space between the mask and the substrate, and in the conventional screen printing machine, the lifting distance for moving the substrate to the mask at the time of printing becomes long. .. Therefore, the conventional screen printing machine has a problem that the cycle time becomes long according to the elevating distance of the substrate. Further, since the moving distance of the substrate is long, a slight error in the moving direction increases the amount of deviation between the substrate and the mask, which causes a problem that the printing accuracy is lowered.

Therefore, an object of the present invention is to provide a screen printing machine in which the position of the substrate corresponds to the height dimension of the image pickup apparatus in order to solve such a problem.

The screen printing machine according to one 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 for transporting, a substrate holding and lifting device that holds the substrate transported by the transport device and positions the mask in the vertical direction, a cleaning device that wipes and cleans the lower surface of the mask, and a reference mark of the mask. It controls the image pickup device that images the image and the reference mark of the substrate, the drive device that moves the image pickup device and the cleaning device between the mask and the substrate holding and lowering device, and each of the devices. Therefore, the elevating portion of the substrate holding elevating device is set to a reference height according to the size of the imaging device, and when the cleaning device is moved, the elevating portion is lowered from the reference height according to the size of the cleaning device. It has a control device to be operated.

According to the above configuration, after the substrate is conveyed by the conveying device to the underside of the mask held by the mask holding device, the substrate is held by the substrate holding elevating device and positioned so as to be in contact with the lower surface of the mask. To. Then, the cream solder is spread from above the mask by the squeegee device, and printing is performed on the substrate. Further, during such substrate printing, an image pickup device enters between the mask and the substrate by a driving device to image a reference mark, and after a predetermined number of printing processes, a cleaning device enters and the underside of the mask enters. Wiping and cleaning is performed. Then, in the substrate holding elevating device, since the elevating part is set to a reference height according to the size of the imaging device during normal printing, the holding substrate is arranged at a close distance to the mask, and when cleaning the mask. , Interference with the cleaning device is avoided by lowering the elevating part.

It is a side view which showed the internal structure of the screen printing machine simplified. It is the figure which showed the structure of the substrate holding lift device of a screen printing machine simplified. It is the figure which showed the movement area of a camera unit and a cleaning unit simply. It is a figure which showed the height of the substrate in a normal state. It is a figure which showed the height of the substrate at the time of cleaning which a cleaning unit moves. It is a figure which conceptually showed the positional relationship of a substrate, a mask, and a camera unit.

Next, an embodiment of the screen printing machine according to the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing the internal structure of the screen printing machine in a simplified manner. This screen printing machine 1 prints 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 the board. Is. In the present embodiment, the front-rear direction of the screen printing machine 1 shown will be described as the Y-axis direction, the width direction of the machine body as the X-axis direction, and the height direction of the machine body 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 from the upper surface to the lower side of the mask through the printing pattern holes. Therefore, the screen printing machine 1 has a mask holder 2 on the upper side so that a mask can be attached. On the upper side of the mask holder 2, a squeegee device 3 for spreading the cream solder on the mask in the front-rear direction of the machine body is installed. On the other hand, on the lower side of the mask holder 2, a substrate holding elevating device 4 for holding the conveyed substrate and moving it in the vertical direction is provided.

Although the screen printing machine 1 is covered with a machine body cover 19 as shown in the figure, transport ports 191 are formed on both side surfaces in the machine body width direction so that the substrate can be carried in and out. Therefore, a substrate transfer device for transporting the substrate in the width direction of the machine body is provided on the lower side of the mask holder 2. Further, on the lower side of the mask holder 2, a clamping device for clamping the substrate in the front-rear direction of the machine body, a backup device for moving the substrate up and down to the clamping position, and the like are assembled to the elevating device. In the present embodiment, the clamp device, the elevating device, and the like are collectively referred to as a substrate holding elevating device 4. FIG. 2 is a simplified view showing the structure of the substrate holding and lowering device 4 of the screen printing machine 1.

First, in the elevating device 8, the elevating table 12 is slidably attached to the guide rail 11 in the vertical direction, and the elevating table 12 is connected to the elevating motor 14 via the ball screw 13. A board transfer device 5 and a clamp device 6 are mounted on the upper part of the elevating table 12 via a support base 15. A pair of mask supports 21 are provided on the support base 15 in the front-rear direction (Y-axis direction) of the machine body, and mask support plates 28 that come into contact with the mask 20 are fixed to the upper surfaces of the legs. A ball screw 22 is configured 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 the mask support motor.

In the clamp device 6, a pair of side frames 25 are arranged in the front-rear direction of the machine body, and each is assembled to a support base 23. A ball screw 26 is configured 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 board clamp motor. A clamp portion 27 is formed on the upper end portion of the pair of side frames 25, and the clamp portions 27 come close to each other so that the substrate 10 can be sandwiched and held. A substrate transfer device 5 composed of 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 by a ball screw and moved up and down by a backup motor 34. Further, the support base 23 of the clamp device 6 is supported by a ball screw and is configured to move up and down by an elevating motor 33. The support base 15 that supports the clamp device 6 and the backup device 7 has a configuration in which the positions of the support base 15 can be adjusted with respect to the elevating base 12 in the X direction, the Y direction, and the θ direction on the XY plane. That is, a correction device for adjusting the positions of the held substrate 10 and the mask 20 is configured.

In the screen printing machine 1, a substrate holding and elevating device 4 in which a clamp device 6 and a backup device 7 are assembled to the elevating device 8 is configured under the mask 20 in this way, and the height of the substrate 10 is gradually adjusted. 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, and this reference height K specifies the transfer height of the substrate 10 to be conveyed by the substrate transfer device 5. It is a thing. That is, when the elevating table 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.

A conveyor belt 29 constituting the substrate transfer device 5 is assembled to the clamp device 6 at a position lower than the clamp portion 27. Therefore, the conveyed substrate 10 is configured to be moved upward by the backup device 7 in order to align the upper surface with the clamp portion 27. After printing, the conveyor belt 29 moves downward, but the height of the upper surface of the conveyor belt 29 is the thickness and the amount of warpage of the substrate 10 that can be processed by the screen printing machine 1 so that the moving distance in the vertical direction becomes smaller. It is set by such as.

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

Next, as shown in FIG. 3, between the mask holder 2 and the substrate holding and lowering device 4, a camera unit 35 (imaging device) and a mask 20 for imaging a reference mark attached to the substrate 10 and the mask 20. A cleaning unit 37 (cleaning device) is provided for cleaning the dirt by wiping it from the lower surface side. FIG. 3 is a simplified view showing the moving periphery of the camera unit 35 and the cleaning unit 37. In particular, the state in which the camera unit 35 and the cleaning unit 37 are separated and only the camera unit 35 has entered between the substrate 10 and the mask 20 is shown. In the screen printing machine 1 shown in FIG. 1, the arrow A1 is the moving range of the camera unit 35 and the cleaning unit 37, and the arrow A2 is the moving 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 front-rear direction of the machine body, and are 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, as in the conventional example. In the drive device, for example, a screw shaft rotated by a drive motor is provided in parallel with the guide rail 41, and a nut fixed to the camera unit 35 side is screwed into the screw shaft to form a ball screw. Then, a coupler is configured in both units so that the cleaning unit 37 can be moved by connecting with the self-propellable camera unit 35.

First, the cleaning unit 37 is configured such that a roll-shaped cleaning paper is used, the used portion is unwound from the first roller 43 before use, and the used portion from which the mask 20 is wiped off is wound by the second roller 44. There is. The cleaning paper 13 is wound (unwinded from the first roller 43) by the servomotor 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.

A solenoid 48 that expands and contracts the plunger up and down is provided in the camera unit 35, and a through hole is formed in the cleaning unit 37 so that the connecting plate 49 projects toward the camera unit 35. Such a solenoid 48 and a connecting plate 49 serve as a coupler for connecting the camera unit 35 and the cleaning unit 37. Therefore, 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, so that the cleaning unit 37 is connected to the camera unit 35 and can be moved integrally. ..

As shown in FIG. 1, the cleaning unit 37 has a standby position at the front portion of the screen printing machine 1. Therefore, when the mask 20 is cleaned by 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, when the plunger of the solenoid 48 is pulled up, the camera unit 35 and the cleaning unit 37 are separated, and the reference mark attached to the substrate 10 or the mask 20 is imaged by moving only the camera unit 35. It has become.

By the way, although the camera unit 35 and the cleaning unit 37 are entirely covered by the unit cover, 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, an air cylinder 45 for pressing the cleaning paper against the mask, and the like are incorporated. In this respect, in the conventional screen printing machine, the distance between the substrate 10 and the mask 20 is designed to correspond to the height dimension of the large cleaning unit 37. Therefore, the moving distance of the substrate 10 becomes long, the cycle time becomes long, and the positional accuracy of the substrate 10 with respect to the mask 20 is lowered.

Therefore, the screen printing machine 1 is configured so that the height of the substrate 10 can be switched between the normal time shown in FIG. 4 and the cleaning time shown in FIG. The normal cleaning unit 37 is arranged 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 printing machine 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 and elevating device 4 in which the substrate transporting device 5 and the like are mounted on the elevating device 8, there is a possibility that the elevating portion that is displaced in the vertical direction interferes with the camera unit 35 and the cleaning unit 37 that enter the lower side of the mask 20. .. Therefore, in the present embodiment, the upper surface of the support plate 28 closest to the mask 20 in such an elevating part is set as the reference height k2. The reference height k2 is the height of the upper surface of the mask support plate 28 when the elevating table 12 is located 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, there is almost no difference between the two distances L1 and L2 and they are about the same. Originally, by setting the distances L1 and L2 to the same value, the distance L3 between the substrate 10 and the mask 20 can be minimized, but the same degree considering the amount of state change such as warpage that can occur in the substrate 10. The value of the distance L1 is slightly larger.

On the other hand, when cleaning the mask 20, as shown in FIG. 5, since the cleaning unit 37 moves to the lower side of the mask 20, not only the camera unit 35 but also the cleaning unit 37 moves between the substrate 10 and the mask 20. It will be. Since the cleaning unit 37 has an upper surface aligned with the camera unit 35 and is enlarged downward, the cleaning unit 37 is configured to descend from the reference height k2 by a predetermined evacuation distance L4 so that the substrate 10 does not interfere with the cleaning unit 37. .. Since the substrate 10 is not always 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 entire drive, and the drive control of each device including the elevating control of the substrate 10 is performed as follows. It has become. First, in 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 pin 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 lifted by driving the elevating 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 heights of the upper surfaces of the mask support plate 28, the clamp portion 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, images of the respective reference marks are performed, and the amount of deviation in the X, Y, and θ directions with respect to the substrate 10 and the mask 20 is based on the imaging data. The calculated position deviation is corrected by the correction device configured on the support base 15.

When the camera unit 35 moves and deviates from the elevating range of the substrate 10, in the substrate holding elevating device 4, the elevating table 12 rises from the position of the reference height K by the drive of the elevating motor 14, and the substrate 10 of the mask 20 It is positioned at a height that contacts the bottom 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 substrate 10 is lowered at a predetermined speed by driving the elevating motor 33, and the substrate 10 is printed with cream solder according to the printing pattern.

When printing is performed on the substrate 10, the elevating table 12 is lowered by the drive of the elevating motor 14 and returned to the position of the reference height K. After that, the clamp device 6 holding the substrate 10 is lowered by driving the elevating motor 33, the backup table 31 is lowered by driving the backup motor 34, and the substrate 10 mounted on the backup pin 32 is returned to the conveyor belt 29. Is done. By returning the positions of the clamping device 6 and the backup device 7 to the substrate transport height shown in FIG. 2 in this way, the substrate 10 can be transported by the substrate transport device 5, and the printed circuit board 10 can be transferred from the screen printing machine 1. It is carried out and a new substrate 10 is carried in.

In the screen printing machine 1, as described above, the printing process on the substrate 10 and the carrying-in / transporting of the substrate 10 are repeatedly performed, and the cleaning of the mask 20 is performed every printing process on a predetermined number of substrates 10. At the time of cleaning the mask, the camera unit 35 moves to the cleaning unit 37 in the standby position as shown in FIG. 1, and the two are connected. 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 thereof.

On the other hand, in the board holding and lowering device 4, the raising and lowering table 12 is lowered by the drive of the raising and lowering motor 14 so that the board 10 and the mask support plate 28 do not interfere with the cleaning unit 37, and is lowered by a predetermined distance from the reference height K. Evacuate to. The retracted position is below the transport height of the substrate. 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. The cleaning unit 37 after cleaning the mask 20 is returned to the standby position again, and the connection with the camera unit 35 is disconnected. Then, 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 / descending distance to the mask 20 is shortened, and the time required for the ascending / descending operation during printing is shortened. Will be done. For example, in the present embodiment, the position of the substrate 10 is 25 mm closer to the mask 20 by corresponding to the camera unit 35 having a smaller size than the conventional example in which the position of the substrate 10 is associated with the cleaning unit 37. Therefore, the moving distance of the substrate 10 at the time of printing becomes a difference of as much as 50 mm in the round trip, and the cycle time can be shortened.

Further, by shortening the moving distance of the substrate 10, the positioning accuracy of the substrate 10 with respect to the mask 20 can be improved. The substrate 10 moves up and down according to the movement of the lifting platform 12 along the guide rail 11, and although the moving direction is designed to match the vertical direction, there is a slight deviation (angle θ) as shown in FIG. ) Will occur. Therefore, at the arrival position of the substrate 10 in contact with the mask 20, a lateral deviation B occurs between the substrate 10 and the mask 20. For example, assuming that the distance L3 between the substrate 10 and the mask 20 is 125 mm in the present embodiment and 150 mm in the conventional example, the difference in lateral deviation B is about 44 μ even if the value of the angle θ is 0.1 °. Will be. Since printing on the substrate 10 requires an accuracy of several tens of μs, this embodiment is also effective in improving the 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 a 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 and lowering device 4 for cleaning, in the case of the cleaning unit 37 having a large height direction according to the cleaning paper, it does not interfere with it. It will be necessary to secure even larger space.

Therefore, the present embodiment solves the drawback that the stroke of the elevating table 12 becomes large during printing while improving the usage efficiency of the cleaning unit 37. That is, the elevating stroke of the elevating table 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 cleaning the mask 20, the elevating table 12 is lowered to create a large space as in the conventional case, so that the demerit of the cleaning unit 37 using the cleaning paper having a large diameter can be eliminated.

Although one embodiment of the present invention has been described above, the present invention is not limited to these, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the cleaning unit 37 is movable by being connected to the self-propellable camera unit 35, but the cleaning unit 37 is also self-propelled by converting the rotational output of the drive motor into a straight motion by a ball screw. It may be a structure. Further, the drive device for traveling each unit may have another structure such as converting the rotation of the drive motor into a linear motion via 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. The structure may be such that the center of the large cleaning unit 37 is above the center in the height direction of the large cleaning unit 37.

1 ... Screen printing machine 2 ... Mask holder 3 ... Squeegee device 4 ... Board holding and elevating device 5 ... Board transfer device 6 ... Clamping device 7 ... Backup device 8 ... Elevating device 9 ... Control device 10 ... Board 14 ... Elevating motor 20 ... Mask 27 ... Clamp part 28 ... Mask support plate 35 ... Camera unit 37 ... Cleaning unit

Claims (4)

A mask holding device that holds the mask and
A squeegee device that spreads cream solder from above on the mask held by the mask holding device, and
A transport device that transports the substrate under the mask,
A substrate holding and elevating device that holds the substrate conveyed by the conveying device and positions the mask in the vertical direction with respect to the mask.
A cleaning device that wipes and cleans the underside of the mask,
An imaging device that captures the reference mark of the mask and the reference mark of the substrate, and
A drive device for moving the image pickup device and the cleaning device between the mask and the substrate holding and lowering device, and
Each device is controlled, and the elevating portion of the substrate holding elevating device is set to a reference height according to the size of the imaging device, and the size of the cleaning device is set when the cleaning device is moved. A control device that lowers the height from the reference height according to
Screen printing machine with. The screen printing machine according to claim 1, wherein the drive device directly moves the image pickup device, and the cleaning device moves the image pickup device via a coupler provided between the drive device and the image pickup device. The screen printing machine according to claim 1 or 2, wherein the reference mark is imaged by the imaging device on the substrate arranged at the holding height by the substrate holding lifting device. Claims 1 to 3 are such that the holding height of the substrate is set so that the distance from the image pickup device that images the reference mark is about the same as the distance between the mask and the image pickup device. The screen printing machine described in any of.

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