JP6940267B2 - Screen printing machine - Google Patents

Description

The present invention relates to a screen printing machine corresponding to the state of the substrate.

In the screen printing machine, a mask having a printing pattern (through holes for printing) is held, and screen printing with cream solder is performed on a substrate arranged under the mask. The screen printing machine includes a substrate transfer device for transporting a substrate, a substrate holding device for holding the transported board and positioning it at a printing location, a mask holding device for positioning and holding a mask, and a screen. A squeegee device or the like is provided on the mask to spread cream solder from the upper surface. Then, the paste-like cream solder is pushed into the printed pattern while rolling on the mask by the squeegee, and is applied (printed) to the substrate located below.

At that time, the substrate is positioned at the printing position directly under the mask. That is, the substrate is transported into the machine by the transport device, then lifted by the board support device, and further clamped by the board holding device. As disclosed in Patent Document 1 below, the substrate support device has a plurality of backup pins erected on a table at positions avoiding electronic components mounted on the substrate, and the table rises. It is configured to support the board from below.

Japanese Unexamined Patent Publication No. 2016-043502 Japanese Unexamined Patent Publication No. 2005-093766

By the way, not all of the substrates supported by the backup pins are conveyed in a flat state, and may be in an upwardly curved upward warp state, a downwardly curved downwardly warped state, or a twisted state. be. Such a state can occur due to the reflow heat during solder melting, for example, because the substrate is sent through the processes of primary printing, component mounting, and reflow. Therefore, when printing the secondary surface of the substrate, if the substrate is in a warped state, the backup pin having a constant height will be in a floating state due to insufficient height. Then, if the squeegee moves while applying printing pressure to the substrate in that state, the substrate and the mask may be deformed when passing through the unsupported floating portion, which may cause a deviation in the printing position. be. Further, there may be a problem that the printed shape is deformed due to the passage of the squeegee and the return of the deformation of the substrate and the mask.

Therefore, an object of the present invention is to provide a screen printing machine corresponding to the state of the substrate in order to solve such a problem.

The screen printing machine according to the present invention holds a mask on which a printing pattern is formed and prints cream solder on a substrate located under the mask, and the mask is provided with a height-adjustable squeegee. A squeegee device that spreads cream solder from above, a transfer device that conveys the substrate under the mask, and a substrate holding device that holds the substrate from a direction orthogonal to the transfer direction. It has a board support device that supports the board from below with a backup pin, an elevating device that raises and lowers the board support device, and a control device that controls the drive of each device. The control device is the squeegee device. On the other hand, the cooling rim solder for adjusting the height of the squeegee is spread while moving according to the change in the tip height of the backup pin in the substrate holding device.

According to the present invention, the substrate is supported from below by a plurality of backup pins having different tip heights. Therefore, for example, if the backup portion composed of the plurality of backup pins is chevron, the substrate is warped. Can also be supported by backup pins according to the condition of the substrate.

It is a figure which showed the internal structure simply about one Embodiment of a screen printing machine. It is the figure which showed the part of the board support device simply. It is a top view which showed the arrangement of the backup pin on the backup table about the substrate support device of 2nd Embodiment. It is sectional drawing which showed the assembly structure of a variable pin.

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 diagram simply showing the internal configuration of the screen printing machine of the present embodiment. The screen printing machine 1 is configured to perform a pre-process of a component mounting machine for mounting electronic components on a substrate. The screen printing machine 1 includes a substrate transfer device 3, a squeegee device 4, a clamp device 5 for gripping the substrate, a substrate support device 7 for supporting the substrate from below, and an elevating device 8 for moving and positioning the substrate in the vertical direction. Etc. are provided. Then, a control device for controlling the entire screen printing machine is mounted, and predetermined control for the drive unit of each device is performed.

In the screen printing machine 1, the substrate 10 is carried in and out by the substrate transfer device 3, and the substrate transfer device 3 is composed of a pair of conveyor belts 11 that support both sides of the substrate 10. The substrate 10 is fed in the direction of penetrating (the width direction of the machine body). Then, the substrate transfer device 3 and the clamp device 5 for holding the substrate 10 are assembled to the elevating device 8. Therefore, the substrate 10 carried into the screen printing machine 1 is held by the clamp device 5, and is positioned at the printing position directly under the mask 9 by ascending. The mask 9 is fitted into the rectangular frame member 18 and attached in a horizontal state.

A linear cream solder is supplied on the set mask 9 in the width direction of the machine body. The cream solder is pushed into the print pattern while rolling on the mask 9 by the squeegee device 4, and is applied to the substrate 10 located under the mask 9. In such a squeegee device 4, a pair of squeegee heads 401 and 402 provided with squeegees are mounted on the traveling table 12 in a state in which the squeegee heads 401 and 402 can be raised and lowered by a cylinder. The traveling table 12 is slidably assembled with respect to the guide rod 13 erected in the lateral direction (front-back direction of the machine body) in the drawing, and can move linearly in the horizontal direction. Further, a screw shaft 15 parallel to the guide rod 13 is erected on the screen printing machine 1 in a rotatable state, and rotation is given by a drive motor. A ball screw mechanism is configured by the fixing nut inside the traveling table 12 and the screw shaft 15.

Next, on the lower side of the set mask 9, a clamp device 5 and an elevating device 8 for gripping and positioning the substrate 10 are configured. First, the elevating device 8 is assembled with an elevating table 22 so as to slide along a vertical guide rail 21, and the elevating table 22 is connected to the elevating motor 23 via a ball screw mechanism 24. A board transfer device 3 and a clamp device 5 are mounted on the elevating table 22 via a support base 25. Although detailed description will be omitted, the support base 25 has a configuration in which the positions of the support base 25 can be adjusted with respect to the lifting base 22 in the X direction, the Y direction, and the θ direction on the XY plane.

A pair of mask supports 26 are erected on the support base 25 in the front-rear direction of the machine body, and a clamp device 5 is arranged between them. Each of the pair of mask supports 26 located in the front-rear direction is provided with a gate-shaped leg body 261 in the width direction of the machine body, and a mask support plate 262 with which the mask 9 comes into contact is fixed on the upper surface thereof. One mask support 26 has a ball screw mechanism in which a fixing nut inside the leg body 261 and one screw shaft 27 are screwed together. Therefore, the distance from the other mask support 26 can be adjusted by controlling the drive motor that rotates the screw shaft 27.

In the clamp device 5, a pair of side frames 33 are erected in front of and behind the support base 31, and a screw shaft 36 is screwed into an internal fixing nut on one side frame 33 to form a ball screw mechanism. The distance from the other side frame 33 can be adjusted by the rotation of the clamp motor with respect to 36. A clamp portion 35 is formed at the upper end portion of the side frame 33 so that the substrate 10 can be gripped from the width direction by adjusting the distance between the side frames 33. In such a side frame 33, a conveyor belt 11 is attached to the lower side of the clamp portion 35, and a substrate transport device 3 for transporting the substrate 10 between the pair of side frames 33 is configured.

Further, a substrate support device 7 is provided between the pair of side frames 33. The board support device 7 has a plurality of backup pins 38 attached to the backup table 37 so as to avoid electronic components mounted on the board 10. The support base 31 of the clamp device 5 is supported via a ball screw mechanism that converts the rotational output of the elevating motor 41 into an elevating motion. Further, the drive motor 42 is fixed to the support base 31, and the backup table 37 is supported via a ball screw mechanism that converts the rotational output of the elevating motor 42 into an elevating motion.

By the way, in the substrate support device 7 of the present embodiment, the plurality of backup pins 38 are not constant in height as in the conventional case, but are configured by different heights. In particular, in the present embodiment, as shown in FIG. 2, the backup pin 381 in the central portion is the tallest when viewed in the left-right lateral direction (moving direction of the squeegee) of the drawing, and the backup pins 382 and 383 located on the left and right sides thereof. Is getting shorter as it goes away from the central part. Since FIG. 2 is a diagram showing a part of the substrate support device 7 in a simplified manner, backup pins 38 (381, 382, 382) changed in three stages are drawn, but more backup pins are drawn. The height may change in multiple stages.

The configuration of the backup pin 38 is designed to correspond to a warped substrate. That is, since the entire backup portion composed of the plurality of backup pins 38 has a chevron shape that matches the warped substrate, the entire backup pin 38 can be supported by the backup pins 38 so that no floating portion is generated on the substrate 10. There is. However, by making the backup portion chevron, even if the substrate conveyed to the screen printing machine 1 is in a flat state or a warped state, the state of the substrate 10 at the time of printing is completely deformed into a chevron shape. Become.

The substrate 10 at the time of printing is pushed up from below by the backup pin 38, and its widthwise end portion is arranged between the pair of clamp portions 35. At this time, in order to bring the substrate 10 in the flat state or the downward warp state into the upward warp state, the end portion of the rising substrate 10 slides with respect to the clamp portion 35, and the advance of the end portion is the central portion due to the sliding resistance. The substrate 10 follows the chevron shape of the backup pin 38. Further, a top-type clamp rail 350 on which the brim portion 351 is formed is attached to the clamp portion 35, and the clamp rail 350 is pressed laterally against the side surface in the width direction of the substrate 10 and in the width direction of the substrate 10. The brim portion 351 is applied to the end portion from above, and the jumping up of the end portion in the width direction is suppressed.

On the other hand, the mask 9 stacked on the substrate 10 is attached in a state of being maintained in a flat state by the frame member 18. Therefore, if the substrate 10 at the time of printing has a chevron shape, the distance between the mask 9 and the substrate 10 will vary. For example, a difference of about 1 to 2 mm is provided between the tallest backup pin 381 and the shortest backup pin 383. Therefore, if the difference in distance between the mask 9 and the substrate 10 is large, the amount of bending of the mask 9 varies depending on the printing pressure received from the squeegee heads 401 and 402, which affects the print quality. In this regard, a configuration is adopted so that the mask 9 at the time of printing imitates the chevron shape of the substrate 10. That is, a plurality of suction holes 263 opened on the upper surface are formed in the mask support plate 262 to which the mask 9 comes into contact, and a vacuum device (not shown) is connected to the suction holes 263.

Therefore, in the screen printing machine 1 having the above configuration, first, the substrate 10 is carried in between the pair of side frames 33 by the conveyor belt 11. Then, the backup table 37 is raised by the drive of the elevating motor 42, and the substrate 10 is lifted from the conveyor belt 11 so as to be pushed up by the backup pin 38, and is supported in a chevron shape as shown in FIG. Further, when the screw shaft 36 is rotated, one side frame 33 moves, and the substrate 10 is sandwiched by the clamp portions 35 of both side frames 33.

Next, by driving the elevating motor 41, the entire clamp device 5 holding the substrate 10 rises, and the clamp portion 35 and the upper surface of the substrate 10 are substantially aligned with the height of the mask support plate 262. .. After that, the elevating table 22 was raised by the drive of the elevating motor 23, stopped at the printing position where the chevron-shaped substrate 10 lightly touched the lower surface of the mask 9, and the similarly raised mask support plate 262 was also positioned directly under the mask 9. Will be done. Therefore, when the vacuum device is driven and the vacuum is drawn through the suction hole 263, the mask 9 is attracted to the upper surface of the mask support plate 262 and flexes so as to follow the chevron substrate 10 as shown in FIG. The state of the mask 9 is maintained.

Then, on the upper surface side of the mask 9, the supplied cream solder is pushed into the print pattern while being rolled on the mask 9 by the squeegee device 4. As a result, the cream solder is printed on the substrate 10 located under the mask 9 through the through holes of the print pattern. At this time, the heights of the squeegee heads 401 and 402 are adjusted by the cylinder while moving according to the height of the upper surface of the mask 9, and the cream solder is rolled at a constant printing pressure. The height adjustment of the squeegee heads 401 and 402 is performed while measuring the change in the height of the upper surface of the mask 9 using a load cell or the like. Alternatively, since the chevron shape on the surface of the mask 9 can be grasped from the height difference of the plurality of backup pins 38, the heights of the squeegee heads 401 and 402 may be adjusted based on the numerical values input in advance.

Therefore, according to the screen printing machine 1 of the present embodiment, the backup portion composed of a plurality of backup pins 38 (381, 382, 382) is formed into a chevron shape, and the state of the substrate 10 at the time of printing is all transformed into a chevron shape. Even if the conveyed substrate 10 is in a warped state, the backup pin 38 supports the entire substrate 10, so that it is possible to prevent quality deterioration such as misalignment of printing.

Subsequently, another embodiment of the substrate support device 7 of the screen printing machine will be described. In the above embodiment, the state of the substrate 10 is configured to change according to the height of the backup pin 38, but the height of the backup pin may be changed according to the state of the substrate 10. FIG. 3 is a plan view showing the arrangement of backup pins on the backup table for the substrate support device of the second embodiment. A plurality of backup pins are regularly arranged vertically and horizontally in the backup table 53. Among the plurality of backup pins, the one shown with hatching is the variable pin 51 whose height can be changed up and down, and the other one is the fixed pin 52 having a constant height.

The variable pin 51 and the fixed pin 52 are about half each, and are arranged alternately on the backup table 53. The fixed pin 52 is fixed upright with respect to the backup table 53, but the variable pin 51 is assembled in a state of being displaceable in the vertical direction while maintaining the upright posture as shown in FIG. FIG. 4 is a cross-sectional perspective view showing the assembly structure of the variable pin 51. As shown in FIG. 4, the backup table 53 is divided into upper and lower two-layer blocks, and in a plan view, as shown in FIG. 3, two rows of a plurality of pins arranged in the longitudinal direction (horizontal direction in the drawing) or one. It is divided into horizontal blocks 531, 532, 533 for rows.

In the backup table 53, the base block 55 of the lower layer and the cylinder block 56 of the upper layer are overlapped with each other. A pin hole 551 opened upward is formed in the base block 55 in the vertical direction, and a movable pin 51 is inserted therein. A piston 511 is formed at the lower end of the movable pin 51, and a spring 57 is loaded between the movable pin 51 and the bottom surface of the pin hole 551. On the other hand, the cylinder block 56 is formed with a cylinder hole 61 which is an open horizontal hole, and the bottom end portion communicates with the air flow path 62. A locking piston 58 provided with an O-ring is inserted into the cylinder hole 61 so that the cylinder hole 61 can slide while maintaining the airtightness in the cylinder hole 61.

The variable pin 51 penetrates the cylinder block 56 so as to cross the cylinder hole 61. Therefore, the cylinder block 56 is vertically formed with pin through holes 63 penetrating at the positions of the cylinder holes 61. The locking piston 58 inserted into the cylinder hole 61 is arranged on the air flow path 62 side behind the variable pin 51 penetrating the cylinder hole 61. That is, the cylinder hole 61 has a working chamber 611 in a space closed by the locking piston 58, and the locking piston 58 can move in the cylinder hole 61 by air pressure. The side of the cylinder hole 61 opposite to the working chamber 611 is opened so as to be open to the atmosphere, so that a gap is provided between the lateral blocks 531, 532, 533.

The air flow path 62 is formed as shown by a broken line in FIG. 3, and is connected to an air pressure adjusting device (not shown) via an air hose. Therefore, the state inside the operating chamber 611 can be controlled to positive pressure or negative pressure by the air pressure adjusting device, and the locking piston 58 moves to the variable pin 51 side in the case of positive pressure, and in the case of negative pressure. Is designed so that the locking piston 58 moves away from the variable pin 51. The tip portion of the locking piston 58, which is operated by positive pressure, is pressed against the variable pin 51 by the rubber material, and the frictional resistance of the locking piston 58 restrains the movement of the variable pin 51 in the vertical direction. .. That is, the variable pin 51 that presses and contracts the spring 57 is temporarily maintained at a predetermined height. On the other hand, the variable pin 51 from which the locking piston 58 is separated by the negative pressure is returned to the original height by the spring 57. Further, at this time, the inside of the working chamber 611 may be released to the atmosphere instead of the negative pressure. This is because the variable pin 51, which has a reduced frictional resistance with the locking piston 58, is returned to its original height by the spring 57.

Therefore, in the screen printing machine 1 provided with such a substrate support device, when the substrate 10 is carried in as described above, the backup table 53 is raised by the drive of the elevating motor 42 and pushed up to the backup pins 51 and 52. The substrate 10 is lifted from the conveyor belt 11. At this time, when the substrate 10 is in a flat state, the spring 57 is compressed by the reaction force from the substrate 10, and the variable pin 51 is lowered. Since the height of the fixed pin 52 corresponds to the flat substrate 10, the height of the variable pin 51 is substantially the same as the height of the fixed pin 52. Further, even when the substrate 10 is in a downward warp state, the bent portion is pushed up and the substrate 10 is in a flat state, so that the height of the variable pin 51 is substantially the same as the height of the fixed pin 52. Become.

On the other hand, when the substrate 10 is in the upward warped state, even if the variable pin 51 is pushed down at the portion warped upward, the variable pin 51 does not fall to the height of the fixed pin 52 and stops in the middle. Therefore, in the case of the upward warp state, a plurality of variable pins 51 are lowered by the reaction force of the substrate 10, but each of them stops at a different height. In this respect, even when the substrate 10 is twisted, the variable pin 51 is displaced according to the height of each part of the substrate, and the entire substrate 10 is supported by the variable pin 51 and the fixing pin 52. Become. However, among the plurality of fixing pins 52, the height may not reach the substrate 10 depending on the location, but the variable pins 51 support the substrate 10 around the fixing pins 52.

Then, after the variable pin 51 is displaced due to the rise of the substrate support device in this way, the inside of the working chamber 611 becomes positive pressure due to the air pressure from the air pressure adjusting device due to the working air, and the locking piston 58 is on the variable pin 51 side. Is pressed against. Therefore, the height of the variable pin 51 pushed down by the reaction force of the substrate 10 is maintained in a state where the upper end thereof is in contact with the substrate 10 due to the frictional resistance with the locking piston 58. After that, the entire clamp device 5 holding the substrate 10 rises, and the clamp portion 35 and the upper surface of the substrate 10 are substantially aligned with the height of the mask support plate 262.

Further, when the elevating table 22 is raised, the substrate 10 is stopped at a printing position where the substrate 10 is in light contact with the lower surface of the mask 9, and the similarly raised mask support plate 262 is also located directly under the mask 9. Then, the vacuum device is driven to evacuate through the suction hole 263. On the upper surface side of the mask 9, the supplied cream solder is pushed into the print pattern while being rolled on the mask 9 by the squeegee device 4. As a result, the cream solder is printed on the substrate 10 located under the mask 9 through the through holes of the print pattern. At this time, the squeegee heads 401 and 402 move while adjusting according to the height of the upper surface of the mask 9, and the cream solder is rolled at a constant printing pressure.

Therefore, according to the screen printing machine 1 of the present embodiment, since the backup pin is composed of a plurality of variable pins 51 and fixed pins 52, the substrate 10 is in a warped state or a twisted state and does not reach the substrate 10. Even if there is a fixed pin 52, the variable pin 51 supports the substrate 10 to prevent quality deterioration such as misalignment of printing. In particular, since the variable pins 51 and the fixed pins 52 are about half each and are arranged alternately on the backup table 53, the variable pins 51 can support the circumference of the fixed pins 52 having insufficient height.

Although one embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made without departing from the spirit of the present invention.
For example, the assembly structure of the variable pin 51 of the second embodiment is an improvement of the pin structure disclosed in US Patent Publication US7942394, but other structures may be used.
Further, in the second embodiment, a plurality of backup pins are arranged regularly in the vertical and horizontal directions for the sake of clarity, but when avoiding electronic components, the backup pins at those locations may be removed. Further, the plurality of backup pins may be irregularly arranged.

Further, the variable pin 51 of the second embodiment is configured such that the spring 57 is compressed by the reaction force from the substrate 10 and the height of the tip thereof follows the state of the substrate 10. In addition to this, for example, an air flow path communicating with the lower side of the piston 511 is formed in the pin hole 551 shown in FIG. 4, and the tip of the movable pin 51 raised by the air pressure follows the state of the substrate 10. You may do so.

1 ... Screen printing machine 3 ... Board transfer device 4 ... Squeegee device 5 ... Clamp device 7 ... Board support device 8 ... Elevating device 9 ... Mask 10 ... Board 11 ... Conveyor belt 35 ... Clamp part 38 ... Backup pin

Claims (5)

In a screen printing machine in which a mask on which a printing pattern is formed is held and cream solder is printed on a substrate located under the mask.
A squeegee device that spreads cream solder on the mask from above with a height-adjustable squeegee,
A transport device that transports the substrate under the mask,
A board holding device that holds the board from a direction orthogonal to the transport direction,
A board support device that supports the board from below with multiple backup pins with different tip heights,
An elevating device that elevates and elevates the board support device, and
It has a control device that controls the drive of each of the above devices.
The control device is characterized in that the squeegee device is spread with a cool rim solder that adjusts the height of the squeegee while moving according to a change in the tip height of a backup pin in the substrate holding device. Screen printing machine. In the substrate support device, the height of the tips of the plurality of backup pins is highest when it is located in the central portion of the mask when viewed in the moving direction of the squeegee, and becomes lower as it is farther from the central portion. The screen printing machine according to claim 1, wherein the screen printing machine is made of the above. In the substrate holding device, a plurality of suction holes opened on the upper surface where the mask contacts the clamp member that sandwiches and holds the substrate in the width direction are formed, and the suction holding means for sucking and holding the mask through the suction holes. The screen printing machine according to claim 1 or 2, wherein the screen printing machine is provided with. The board support device has a plurality of backup pins having a variable pin having a high tip height and a fixing pin having a low tip height, and the variable pin can be positioned at a position lowered by a reaction force from the board. The screen printing machine according to claim 1, further comprising a variable mechanism. The screen printing machine according to claim 4, wherein the substrate support device is a device in which a plurality of the variable pins and the fixing pins are arranged on a table in a substantially even state.

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