JP6694778B2 - Screen printer - Google Patents

Description

  The present invention relates to a screen printing device that sequentially prints a viscous material on a substrate in two screen printing units.

  A screen printing apparatus is known in which a viscous material such as a solder paste is applied onto a printed circuit board by using a mask having a pattern opening. In the screen printing device, the contamination of the mask becomes a problem. When the solder paste adheres to the surface of the mask facing the substrate, the solder paste is printed at an unintended position on the substrate, which causes printing failure.

  Patent Document 1 discloses a screen printing apparatus that detects a stain on the back surface of the mask (the surface facing the substrate) and performs a cleaning process on the mask when the stain is detected. In this device, an image of the back surface of the mask is taken, and the presence or absence of the solder paste that has flowed around the back surface of the mask is detected from the image. When the solder paste is detected, the back surface of the mask is cleaned. Patent Document 2 also discloses a screen printing apparatus that captures an image on the back surface of a mask in order to detect clogging of a pattern opening.

JP, 2000-309089, A JP-A-5-229109

  In some screen printing apparatuses, solder paste may be sequentially printed on a substrate by two screen printing units. For example, first, a first printing process for printing a solder pattern for a small component on a substrate using a thin mask is performed, and then a thick mask is used for the large component for the substrate after the first printing process. There is a sequential printing type screen printing apparatus that performs a second printing process for printing a solder pattern. In this type of screen printing apparatus, when the inappropriate first printing process is performed, the solder paste is printed on a portion of the substrate that should not be printed, and the solder paste is printed on the back surface of the mask in the second printing process. May adhere. In this case, there arises a problem that the subsequent second printing process is hindered, that is, a substrate having a printing defect is generated.

  An object of the present invention is to provide a screen printing apparatus that sequentially prints a viscous material on a substrate in two screen printing units and that can prevent the occurrence of printing defects due to the adhesion of the viscous material to a mask. To do.

A screen printing apparatus according to an aspect of the present invention includes a first mask and a first printing unit, a first screen printing unit that performs a first printing process of screen-printing a viscous material on a substrate, a second mask, and A second screen printing unit including a second printing unit for performing a second printing process of screen-printing a viscous material on the substrate subjected to the first printing process; and the first printing process or the second printing process. As a predicted adhesion position of the viscous material due to, an image capturing unit that captures an image of a designated point designated in advance, and whether or not the viscous material exists at the designated point based on an image acquired by the image capturing unit. in the screen printing apparatus comprising a determining unit, wherein the designated point is a specific position of the substrate on which the first printing process is performed, the imaging unit certain of the substrate after the first printing process And a viscous material in the first printing process in which the specific position of the substrate is regular, further comprising a printing control unit that controls operations of the first printing process and the second printing process. When the determination unit determines that the viscous material is present at the non-regular position, the print control unit suspends execution of the second printing process. .
A screen printing apparatus according to another aspect of the present invention includes a first mask and a first printing unit, and a first screen printing unit that performs a first printing process of screen-printing a viscous material on a substrate; A second screen printing unit that includes a second mask and a second printing unit and that performs a second printing process of screen-printing a viscous material on the substrate that has been subjected to the first printing process; and the first printing process or the first printing process. 2 As an estimated position of adhesion of the viscous material due to the printing process, whether the viscous material exists at the designated point based on an image capturing unit that captures a designated point that is designated in advance and an image acquired by the image capturing unit. In a screen printing device including a determination unit that determines whether or not,
The designated point is a specific position of the substrate on which the first printing process has been performed, and the imaging unit captures an image of the specific position of the substrate after the first printing process. The print control unit may further include a print control unit that controls an operation of the second print process, wherein the specific position of the substrate is a predetermined regular position to which the viscous material adheres in the regular first print process. When the determination unit determines that the viscous material does not exist at the regular position, the second printing process is stopped.

  According to this screen printing device, the image capturing unit captures an image of a designated point as a predicted sticking position of the viscous material. The predicted adhesion position is, for example, a position where the viscous material adheres when an assumed incorrect printing process is performed, or a position where the viscous material adheres when a regular printing process is performed. Is. Then, the determination unit determines whether or not the viscous material is present at the designated point. Whether or not erroneous printing processing or regular printing processing has been performed can be grasped based on the presence or absence of the viscous material at the designated point. Therefore, it is possible to take various measures to prevent the occurrence of print defects based on the determination result of the determination unit.

  In the above screen printing apparatus, the designated point may be a specific position on the back surface of the second mask, and the imaging unit may be configured to image the specific position of the second mask after the second printing process. desirable.

  According to this screen printing device, the determination unit can determine whether the viscous material is attached to the back surface of the second mask. For example, when the first printing process is executed in a state where the first mask is not attached to the regular position, the positions of the printing pattern by the first printing process on the substrate and the escape pattern provided in the second mask are When they do not match, the viscous material adheres to the back surface of the second mask (the surface facing the substrate). In addition, the attachment error of the first mask is generally caused by reversing the attachment to the proper position, and when the error occurs, it is not possible to predict which position of the second mask the viscous material will adhere to. it can. Therefore, it is possible to detect an error in the first printing process by detecting the adhesion of the viscous material to the specific position on the back surface of the second mask, and it is possible to prevent the subsequent printing failure.

  In this case, the cleaning unit may further include a cleaning unit that cleans a back surface of the second mask, and the cleaning unit may clean the second mask when the determination unit determines that the viscous material is present on the back surface of the second mask. It is desirable to clean the back side.

  According to this screen printing device, the viscous material attached to the back surface of the second mask is removed by the cleaning unit. Therefore, in the subsequent second printing process, it is possible to prevent the viscous material from adhering to an unintended portion of the substrate from the second mask.

  In the above screen printing apparatus, the designated point is a specific position of the substrate on which the first printing process is performed, and the imaging unit is configured to capture an image of the specific position of the substrate after the first printing process. Is desirable.

  According to this screen printing device, the imaging unit images the specific position of the substrate after the first printing process. As a result, it is possible to confirm whether or not the first printing process has been properly executed.

  The screen printing apparatus may further include a print control unit that controls operations of the first printing process and the second printing process, and the viscous material may be attached in the first printing process when the specific position of the substrate is regular. When the determination unit determines that the viscous material is present at the non-regular position, the print control unit may stop execution of the second print process. desirable.

  According to this screen printing device, the second printing process is stopped when the adhesion of the viscous material to the irregular position of the substrate is detected. Factors that cause the viscous material to adhere to the non-regular position include a mounting error of the first mask and a positioning error of the substrate when the substrate is moved from the first screen printing unit to the second screen printing unit. When such an error occurs, the print control unit suspends the execution of the second print process, so that it is possible to prevent the occurrence of print defects.

  The screen printing apparatus may further include a print control unit that controls the operations of the first printing process and the second printing process, and the viscous material may adhere to the specific position of the substrate in the regular first printing process. When the determination unit determines that the viscous material does not exist at the regular position, the print control unit preferably stops the execution of the second printing process.

  According to this screen printing device, the second printing process is stopped when the adhesion of the viscous material to the regular position of the substrate is not detected. Factors that prevent the viscous material from adhering to the proper position include a mounting error of the first mask and a positioning error of the substrate when moving the substrate. When such an error occurs, the print control unit suspends the execution of the second print process, so that it is possible to prevent the occurrence of print defects.

  In this case, it further comprises a substrate transport unit that transports the substrate from the first screen printing unit to the second screen printing unit, the imaging unit is disposed in the first screen printing unit, the print control unit, In order to stop the execution of the second printing process, it is desirable to stop the transportation of the substrate by the substrate transportation unit from the first screen printing unit to the second screen printing unit.

  According to this screen printing apparatus, when a problem occurs in the first printing process, the substrate is not conveyed to the second screen printing unit. Therefore, it is possible to promptly take countermeasures against printing defects.

  In the above screen printing apparatus, the first mask has a predetermined first thickness and a predetermined first pattern opening, and the second mask has a second thickness larger than the first thickness. A predetermined second pattern opening and a relief recess provided at a position corresponding to the first pattern opening can be provided.

  According to this screen printing apparatus, the present invention can be applied to a sequential printing type screen printing apparatus in which the first printing process for small parts and the second printing process for large parts that follow are performed. That is, the print pattern of the first printing process is not avoided by the escape recesses of the second mask, and it is possible to prevent the occurrence of printing defects due to the viscous material adhering to the second mask.

  In the above screen printing apparatus, each of the first and second screen printing units has an independent device configuration, is arranged between the first screen printing unit and the second screen printing unit, and is accessible by an operator. It can be configured to further include a connection conveyor that conveys the substrate in the state.

  According to this screen printing apparatus, it is possible for the operator to take out the substrate which has been conveyed through the connection conveyor after the first printing process is completed. When the board is returned to the connection conveyor, a mistake in the mounting direction of the board may be made. However, according to the present invention, such a mistake can be detected and a printing failure can be prevented from occurring in the second printing process.

  According to the present invention, in a screen printing apparatus that sequentially prints a viscous material on a substrate in two screen printing units, it is possible to prevent the occurrence of print defects due to the adhesion of the viscous material to the mask.

FIG. 1 is a plan view of a screen printing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic side view of the screen printing device in the Y direction. FIG. 3 is a schematic side view of the screen printing device in the X direction. FIG. 4 is a vertical cross-sectional view showing an example of a mask, FIG. 4 (A) shows a mask for small parts, and FIG. 4 (B) shows a mask for large parts. FIG. 5 is a schematic diagram showing an operation of sequential printing. FIG. 6 is a schematic diagram showing an operation of sequential printing. FIG. 7 is a schematic diagram showing an operation of sequential printing. FIG. 8 is a schematic diagram showing the operation of sequential printing. FIG. 9 is a schematic diagram showing the operation of sequential printing. FIG. 10 is a schematic diagram showing an operation of sequential printing. FIG. 11 is a schematic diagram showing a failure example of sequential printing. FIG. 12 is a block diagram showing an electrical configuration of the screen printing apparatus. FIG. 13 is a flowchart showing the first embodiment of the operation of the screen printing apparatus. FIG. 14 is a flowchart showing a second embodiment of the operation of the screen printing device. FIG. 15 is a flowchart showing a third embodiment of the operation of the screen printing device. FIG. 16 is a schematic diagram for explaining the fourth embodiment of the operation of the screen printing device. FIG. 17 is a schematic diagram for explaining the fifth embodiment of the operation of the screen printing device. FIG. 18 is an explanatory diagram of print misalignment in the fifth embodiment.

[Overall structure of screen printing device]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1 is a plan view of a screen printing apparatus 100 according to an embodiment of the present invention, FIG. 2 is a schematic side view in the Y direction of the screen printing apparatus 100, and FIG. 3 is a schematic side view in the X direction. is there. In this embodiment, a screen printing apparatus 100 that mask-prints a solder paste on the upper surface of a printed circuit board (hereinafter, referred to as a board 5) is illustrated. That is, in the present embodiment, the viscous material is solder paste.

  As shown in FIG. 1, in the screen printing apparatus 100, the substrate 5 is loaded from the loader LD at the loading position En on the upstream side (the right side in the X direction) in the transport direction, the screen printing process is performed on the substrate 5, and the transport direction is set. The substrate 5 is unloaded from the unloading position Ex on the downstream side (left side in the X direction) to the downstream apparatus M. The transport direction of the substrate 5 is the X direction, and the direction orthogonal to the X direction in the horizontal plane is the Y direction. Further, the up-down direction orthogonal to the X and Y directions is the Z direction. The downstream device M is, for example, a component mounting device that mounts various electronic components on the substrate 5 on which the solder paste is printed.

  The screen printing apparatus 100 includes a base 1, a board working table 2 that holds and conveys a board 5, and a first screen printing section 3A and a second screen printing section 3B that screen print solder paste on the board 5. I have it. The first screen printing unit 3A performs a first printing table 30A provided with a small component mask 6 (first mask) and a first printing process of screen-printing a solder paste on the substrate 5 through the small component mask 6. And a first squeegee unit 4A (first printing unit) for performing. The second screen printing unit 3B solders to the second printing table 30B provided with the large-sized component mask 7 (second mask) and the substrate 5 on which the first printing process has been performed via the large-sized component mask 7. A second squeegee unit 4B (second printing unit) for performing a second printing process of screen-printing the paste. Further, the screen printing apparatus 100 has a built-in control unit 90 (see FIG. 12) described later for controlling the operation of each unit described below.

  The base 1 is disposed below the screen printing apparatus 100 and supports each device included in the screen printing apparatus 100. The substrate work table 2 is arranged on the base 1, receives the substrate 5 at the carry-in position En, and sequentially supports and fixes the substrate 5 facing the first and second printing tables 30A and 30B during the printing work. It has a function to carry out the printed substrate 5 from the carry-out position Ex. The second loader LDs may be arranged side by side in the Y direction, and the second substrate work table 2 may be arranged on the base 1 so as to be arranged in the Y direction.

  The substrate work table 2 includes a movable base 21 that is movable in the Y direction, a transfer conveyor 22 arranged on the movable base 21, a clamp unit 23, a mask recognition camera 24 (imaging unit), and a cleaning unit 25 (cleaning unit). Including and The transport conveyor 22 includes a pair of conveyor rails extending in the transport direction (X direction). The clamp unit 23 is a mechanism for moving the substrate 5 on the transport conveyor 22 in the X direction while holding the substrate 5 above the transport conveyor 22 so as to be able to perform a printing operation in a state of being separated from the transport conveyor 22 upward. The mask recognition camera 24 is attached to the clamp unit 23. The cleaning unit 25 is arranged on the movable table 21.

  The movable base 21 is supported by a guide rail 11 arranged on the base 1 so as to extend in the Y direction so as to be movable in the Y direction. The movable base 21 is moved in the Y direction on the guide rail 11 by the table drive mechanism. Specifically, the movable base 21 is moved in the Y direction by the screw shaft 12 extending in the Y direction and the servo motor 13 that rotationally drives the screw shaft 12. The movable range of the movable table 21 in the Y direction is set so as to be movable to positions directly below the first and second printing tables 30A and 30B.

  The transport conveyor 22 includes a pair of conveyor rails extending over substantially the entire length of the screen printing apparatus 100 in the X direction. The substrate 5 can be loaded and unloaded by matching the position of the transfer conveyor 22 with the Y-axis coordinates of the loading position En and the unloading position Ex. It is possible to move one of the pair of conveyor rails of the conveyor 22 in the Y direction on the movable table 21. Therefore, the conveyor width (interval between the conveyor rails) can be changed according to the size of the substrate 5 to be transported.

  The clamp unit 23 is a movable unit arranged so as to hold the pair of conveyor rails of the conveyor 22 from both outsides in the Y direction. The clamp unit 23 can be moved in the X direction on the guide rail 51a by an X-axis moving mechanism 51 (see FIG. 2) provided on the movable table 21. That is, the clamp unit 23 is movable in the X direction along the transport conveyor 22. The width of the clamp unit 23 in the Y direction can be changed according to the conveyor width of the conveyor 22.

  The clamp unit 23 includes a clamp mechanism 52 for holding and fixing the side edge of the substrate 5, and a support mechanism 53 for lifting and supporting the substrate 5 on the transport conveyor 22. As shown in FIG. 3, the clamp mechanism 52 includes a fixed clamp portion 52 a arranged along the side of the substrate 5 in the Y2 direction and a movement of the clamp mechanism 52 arranged along the side of the substrate 5 in the Y2 direction. And a clamp portion 52b. The movable clamp part 52b can be moved in a direction approaching the fixed clamp part 52a by driving an air cylinder (not shown), and thus the clamp mechanism 52 sandwiches the substrate 5 on the transfer conveyor 22 from both sides in the Y direction. Can be clamped. The clamp is released by operating the air cylinder in the opposite direction.

  The support mechanism 53 includes a plurality of backup pins 53a and an elevating mechanism 53b that moves the backup pins 53a up and down. The backup pin 53 a is provided upright on the lower side of the substrate 5 and has a pin tip portion that abuts the lower surface of the substrate 5. The elevating mechanism 53b raises the backup pin 53a to bring the tip end of the pin into contact with the lower surface of the substrate 5, and further lifts and supports the substrate 5 on the transport conveyor 22. The substrate 5 lifted by the support mechanism 53 is gripped by the clamp mechanism 52, so that the substrate 5 is fixedly held in a state of being separated upward from the transport conveyor 22. Thereby, it becomes possible to perform the screen printing work on the substrate 5 on the substrate work table 2.

  The mask recognition camera 24 is composed of a CCD area sensor or the like, and is attached to the outside of the clamp unit 23 in the Y1 direction with the imaging direction facing upward. Therefore, the mask recognition camera 24 can move in the Y direction as the substrate work table 2 moves, and can move in the X direction as the clamp unit 23 moves. The mask recognition camera 24 makes mask recognition marks provided on the lower surface side of the screen masks (the mask 6 for small components and the mask 7 for large components described later) held by the first and second screen printing units 3A and 3B, respectively. Image from below. From the image data obtained by this imaging, the position and orientation of the screen mask are recognized.

  The cleaning unit 25 is a cleaner for the screen mask. The cleaning unit 25 includes a cleaning head including a pad that comes into contact with the substrate contact surface (lower surface) of the screen mask and a suction nozzle that performs negative pressure suction through the pad. While the cleaning head is in contact with the substrate contact surface of the screen mask, the substrate work table 2 and the screen mask are relatively moved (slipped) in the Y direction to adhere to the substrate contact surface and the pattern opening. Removed solder paste. The cleaning head can move up and down with respect to the substrate work table 2, and is retracted to a descending position where it is not in contact with the screen mask except when cleaning the mask.

  In addition to the original role described above, in one embodiment of the present invention, the mask recognition camera 24 specifies the screen mask (in this embodiment, the mask 7 for large parts in this embodiment) previously specified as a predicted solder paste attachment position. It also plays the role of imaging points. The cleaning unit 25 cleans the screen mask when it is determined that the solder paste is present at the designated point. These points will be described in detail later.

  A pair of frame structures 14 are erected on the base 1. The pair of frame structures 14 extend in the Y direction across the upper side of the substrate work table 2 and are arranged at predetermined intervals in the X direction. Each frame structure 14 has a gate structure, and a pair of legs 14a extending upward from the vicinity of both ends of the base 1 in the Y direction and a beam connecting the upper ends of the legs 14a in the horizontal direction. And a portion 14b.

  Two board recognition cameras 15 (see FIG. 3) are fixedly installed on the lower surface side of the frame structure 14 (the beam portion 14b) on the upstream side (the right side in FIG. 1) in the transport direction straddling over the board work table 2. Has been done. The board recognition camera 15 is a camera for capturing an image of the board 5 on the board work table 2. The board recognition camera 15 includes a CCD area sensor and the like, and is installed with the imaging direction facing downward. The board recognition camera 15 images a board recognition mark (not shown) provided on the upper surface of the board 5. From the image data obtained by this imaging, the position and orientation of the substrate 5 gripped by the clamp unit 23 is recognized.

  In addition to this function, the board recognition camera 15 also plays a role of picking up an image of a specified point of the board 5 which is previously specified as a predicted solder paste attachment position in another embodiment of the present invention. The designated point is a position where the solder paste is attached in the regular printing process, a position where the solder paste cannot be attached in the regular printing process, or the like. These points will be described in detail later.

  The first printing table 30A is supported on both sides in the X direction by a pair of guide rails 33a provided on the pair of frame structures 14, and is arranged above the substrate work table 2. The first printing table 30A is movable in the Y direction along a guide rail 33a extending in the Y direction, and is also movable in the vertical direction (Z direction). Similarly, the second printing table 30B is also supported by the guide rails 33a and is movable in the Y direction. Each of the first and second printing tables 30A and 30B has a substantially rectangular mask fixing member 31 to which a screen mask is detachably assembled, and a mask elevating mechanism 32 for elevating (moving in the Z-axis direction) the mask fixing member 31. It has a pair of mask drive mechanisms 33 for rotating the mask fixing member 31 around the Z axis and moving it in the Y direction.

  The mask 6 for small components is assembled to the mask fixing member 31 of the first printing table 30A. FIG. 4A is a vertical cross-sectional view schematically showing an example of the small component mask 6. The small component mask 6 has a predetermined first thickness t1 and has a predetermined small pattern opening 61 (first pattern opening). The small pattern opening 61 is a minute opening punched in a pattern corresponding to, for example, a 0402 size electronic component or a small electronic component such as a BGA having a ball pitch of 0.4 mm. The first thickness t1 is set to a thickness suitable for the small electronic component. The suitable first thickness t1 is, for example, 70 μm. By performing screen printing using the small component mask 6, a solder pattern corresponding to the small pattern openings 61 is printed on the surface of the substrate 5. The height of the solder pattern is the same as the first thickness t1, or is slightly smaller than the first thickness t1 due to gravity acting on the solder pattern.

  On the other hand, the mask 7 for large parts is assembled to the mask fixing member 31 of the second printing table 30B. FIG. 4B is a vertical sectional view schematically showing an example of the mask 7 for large parts. The large component mask 7 has a second thickness t2 that is thicker than the first thickness t1, and is provided at a position corresponding to a predetermined large pattern opening 71 (second pattern opening) and a small pattern opening 61. The escape recess 72 is provided. The large pattern opening 71 is a relatively large opening perforated in a pattern corresponding to a large electronic component such as a shield case. The second thickness t2 is set to a thickness suitable for the large electronic component. A suitable second thickness t2 is, for example, 130 μm. By performing screen printing using the large component mask 7, a solder pattern corresponding to the large pattern opening 71 is printed on the surface of the substrate 5. The height of the solder pattern is the same as the second thickness t2 or slightly smaller than the second thickness t2.

  The escape recess 72 is provided on the substrate contact surface (lower surface) side of the large component mask 7. The position corresponding to the above-mentioned small pattern opening 61 means that the substrate 5 on which a solder pattern for a small component is formed by screen printing using the mask 6 for a small component and the same substrate 5 using the mask 7 for a large component. This means the position where the small component solder pattern faces the large component mask 7 when additional screen printing is performed (sequential printing). The recess depth t3 of the escape recess 72 is set to be larger than the first thickness t1 of the small component mask 6. Moreover, the XY size of the escape recess 72 is set to a size that can surround the portion where the solder pattern for a small component is formed.

  Therefore, when the mask 5 for large components is subjected to plate alignment for sequential printing on the substrate 5 after the first printing process using the mask 6 for small components, the small components formed by the mask 6 for small components are formed. The soldering pattern for soldering is accommodated inside the escape recess 72, and the mask 7 for large-scale parts and the soldering pattern are kept in non-contact with each other. By performing the second printing process using the mask 7 for large components in this state, the solder pattern for large components is printed on the substrate 5 in addition to the solder pattern for small components.

  The mask elevating mechanism 32 is a mechanism for elevating the mask fixing member 31. The mask elevating mechanism 32 supports the mask fixing member 31 and also elevates and lowers the mask fixing member 31 by a guide, a screw shaft, and a Z-axis motor that drives the screw shaft, which are not shown. The mask elevating mechanism 32 is supported on the pair of guide rails 33a at both ends in the X direction.

  The pair of mask drive mechanisms 33 includes a pair of guide rails 33a and a screw shaft 33b extending in the Y direction, and two Y-axis motors 33c that drive the pair of screw shafts 33b, respectively. Are installed in each. The pair of mask driving mechanisms 33 can independently drive the mask elevating mechanism 32 in the Y direction from both sides in the X direction. By driving both the pair of mask driving mechanisms 33 at a constant speed, the mask fixing member 31 can be moved in parallel with the mask elevating mechanism 32 in the Y direction. On the other hand, if a difference is provided in the driving amount between the pair of mask driving mechanisms 33, the mask fixing member 31 can be rotated together with the mask elevating mechanism 32 in the horizontal plane (the XY plane).

  With the mechanism described above, it is possible to move the first and second printing tables 30A and 30B to arbitrary positions in the Y direction within the movement range to perform printing on the substrate 5, and hold the mask 6 for small components. Alternatively, it is possible to perform detailed alignment (position in the Y direction and inclination in the horizontal plane) in the XY plane of the mask 7 for large parts. Positioning in the X direction is performed by adjusting the movement of the clamp unit 23. At the time of printing, the first and second printing tables 30A and 30B perform a plate matching operation of lowering in the Z2 direction by the mask elevating mechanism 32 to bring the masks 6 and 7 into contact with the upper surface of the substrate 5, and after printing, A plate separating operation is performed in which the masks 6 and 7 are lifted in the direction to separate from the upper surface of the substrate 5.

  The first squeegee unit 4A is supported by the central portion of the movable beam 42 extending in the X direction and is arranged above the first printing table 30A. The second squeegee unit 4B is supported by the central portion of the other movable beam 42 and is arranged above the second printing table 30B. The first and second squeegee units 4A and 4B respectively include a squeegee 41 (see FIG. 2) that reciprocates and slides in the Y direction while pressing the solder paste against the upper surfaces of the masks 6 and 7, and a squeegee 41 during printing. An elevation mechanism (not shown) that raises and lowers the squeegee, and a squeegee angle varying mechanism (not shown) for changing the inclination direction and the inclination angle of the squeegee 41 with respect to the mask 6 and the mask 7.

  The movable beam 42 is movably supported on a pair of guide rails 43 provided on the upper surfaces of the pair of frame structures 14 so as to extend along the Y direction. The movable beam 42 is moved in the Y direction by a screw shaft 44 provided in the frame structure 14 and extending in the Y direction and a squeegee shaft motor 45. Each squeegee 41 slides in the Y direction on the upper surfaces of the masks 6 and 7 by the first and second squeegee units 4A and 4B moving in the Y direction as the movable beam 42 moves, and performs the printing operation. .. The first squeegee unit 4A performs the first printing process on the substrate 5 by using the first printing table 30A provided with the small component mask 6. After the first printing process, the second squeegee unit 4B performs the second printing process on the same substrate 5 by using the second printing table 30B provided with the large component mask 7. The procedure of such sequential printing will be illustrated below.

[Procedure for sequential printing]
5 to 10 are schematic diagrams showing the sequential printing operation by the first and second screen printing units 3A and 3B in chronological order. In the sequential printing, first, in the first screen printing unit 3A, the first printing process of screen-printing the solder pattern for the small component on the substrate 5 using the mask 6 for the small component is executed. As shown in FIG. 5, the substrate working table 2 moves the substrate 5 to directly below the small component mask 6 held by the mask fixing member 31 of the first printing table 30A. A squeegee 41 holding a solder pool Sd, which is a mass of solder paste, is in contact with the upper surface of the small component mask 6.

  Subsequently, as shown in FIG. 6, the mask elevating mechanism 32 lowers the mask 6 for small components together with the mask fixing member 31, and a plate-matching operation for bringing the mask 6 for small components into contact with the upper surface of the substrate 5 is performed. At this time, the squeegee 41 is also lowered. Then, the squeegee 41 slides rightward (Y direction) on the small component mask 6 while pressing the solder pool Sd against the upper surface of the substrate 5. As a result, the small pattern Sd1 corresponding to the small pattern opening 61 of the small component mask 6 is printed on the upper surface of the substrate 5 (first printing process).

  Thereafter, as shown in FIG. 7, a plate separating operation for separating the small component mask 6 from the upper surface of the substrate 5 upward is performed in the first screen printing unit 3A. The squeegee 41 is also raised at the same time. The substrate 5 for the first printing process is moved to the second screen printing unit 3B. That is, the substrate work table 2 moves the substrate 5 on which the small pattern Sd1 is printed to directly below the mask 7 for large components held by the mask fixing member 31 of the second printing table 30B. A squeegee 41 holding a solder pool Sd is in contact with the upper surface of the large component mask 7.

  Then, the plate matching operation of the mask 7 for large parts is performed. FIG. 8 shows a state in which the mask elevating mechanism 32 of the second printing table 30B lowers the mask 7 for a large component together with the mask fixing member 31, and the mask 7 for a large component is brought into contact with the upper surface of the substrate 5. .. At the time of this plate alignment, the small pattern Sd1 previously printed on the substrate 5 is accommodated in the escape recess 72. As described above with reference to FIG. 4, since the relationship between the first thickness t1 of the small component mask 6 and the recess depth t3 of the escape recess 72 is t1 <t3, the small pattern Sd1 contacts the large component mask 7. There is nothing to do.

  Thereafter, the squeegee 41 slides in the left direction (Y direction) on the large component mask 7 while pressing the solder pool Sd against the upper surface of the substrate 5. As a result, the large pattern Sd2 corresponding to the large pattern opening 71 of the large component mask 7 is additionally printed on the upper surface of the substrate 5 (second printing process). After that, as shown in FIG. 10, a plate separating operation is performed in the second screen printing unit 3B to separate the mask 7 for large components from the upper surface of the substrate 5 upward.

  As described above, according to the screen printing apparatus 100 capable of performing sequential printing, a pattern opening for solder paste printing required for one substrate 5 is provided with a small pattern of the mask 6 for small components having different thicknesses. The opening 61 and the large pattern opening 71 of the mask 7 for large parts are shared and the printing process is performed individually. As a result, a small pattern Sd1 and a large pattern Sd2, which are solder patterns having an aspect ratio (solder height / solder bottom area, that is, mask thickness / opening area) according to the component size, are formed on the surface of the substrate 5, respectively. be able to. Alternatively, by changing the viscous material used in the first and second screen printing units 3A and 3B, printing of different viscous materials (for example, printing with solder paste and adhesive) can be performed.

[Causes of print defects in sequential printing]
The sequential printing has the above-mentioned merits, but a printing failure occurs due to performing the first printing process and the second printing process on one substrate 5 twice. Sometimes. One of them is an incorrect mounting direction of the screen mask. FIG. 11 is a schematic diagram showing a failure example of sequential printing due to a mask mounting error. Here, the case where the mask 6 for small components is attached to the mask fixing member 31 of the first screen printing unit 3A in a state where the mounting direction is 180 ° reversed with respect to the regular direction is illustrated. In general, the screen mask has a rectangular shape in a plan view, and the operator does not make a mistake in the mounting direction by 90 °, but the operator may perform 180 ° inverted mounting.

  When the first printing process is performed in this state, the small pattern Sd1 is printed not at the predetermined regular position on the substrate 5 but at the non-regular position corresponding to the inverted small pattern opening 61. .. When the substrate 5 with such a small pattern Sd1 is transferred to the second screen printing unit 3B and plate matching is performed with the mask 7 for large parts for the second printing process, the solder paste of the small pattern Sd1 becomes large. It adheres to the lower surface of the component mask 7. That is, since the escape recess 72 of the large component mask 7 and the small pattern Sd1 on the substrate 5 are not aligned with each other, the small pattern Sd1 contacts the lower surface of the large component mask 7.

  When such a mask mounting error occurs, it goes without saying that the substrate 5 on which the small pattern Sd1 is printed at the non-regular position becomes defective in printing. In addition to this, since the solder paste adhered to the mask 7 for large-sized components is transferred to the substrate 5 to be printed after the substrate 5, the substrate 5 with further printing failure is induced. Will be lost.

  A similar problem may occur due to an error in the loading direction of the substrate 5. The first screen printing unit 3A and the second screen printing unit 3B each have an independent device configuration, and an operator can temporarily take out the substrate 5 between the two printing units for the purpose of inspection or visual confirmation. There are cases. In this case, when the operator re-feeds the taken-out substrate 5 to the printing line, the loading direction may be wrong. What can occur is an error that the substrate 5 is re-introduced in a state of being inverted by 180 ° with respect to the regular insertion direction. Even in such a case, the solder paste of the small pattern Sd1 adheres to the lower surface of the large component mask 7 in the same manner as that shown in FIG. In the present embodiment, a screen printing apparatus 100 that suppresses such printing defects is provided.

[Electrical configuration of screen printing device]
FIG. 12 is a block diagram showing the electrical configuration of the screen printing apparatus 100. In addition to the board recognition camera 15 and the mask recognition camera 24 described above, the screen printing apparatus 100 includes a sensor 81, a board transfer motor 82, a work table drive section 83, a cleaning drive section 84, a clamp drive section 85, a mask drive section 86, A squeegee drive unit 87 and a control unit 90 (print control unit) are provided.

  In the present embodiment, the board recognition camera 15 and the mask recognition camera 24 functioning as the image pickup unit perform the first image pickup performed by the first and second screen printing units 3A and 3B in addition to the original image pickup for substrate recognition and mask recognition. A designated point designated in advance is imaged as a predicted solder paste attachment position due to the second printing process.

  To exemplify a specific mode, the board recognition camera 15 arranged in the first screen printing unit 3A has a regular position on the board 5 after the first printing processing to which the solder paste is attached by the regular printing processing, or a regular position. In the printing process of 1, the non-regular position where the solder paste cannot be attached is imaged. The board recognition camera 15 arranged in the second screen printing section 3B has the above-mentioned regular position of the board 5 introduced into the second screen printing section 3B after the first printing processing or the board 5 after the second printing processing. An image of the irregular position is captured. The mask recognition camera 24 images the specific position on the back surface of the small component mask 6 after the first printing processing or the specific position on the back surface of the large component mask 7 after the second printing processing. The specific position is a designated point where the solder paste is expected to adhere when the mask 6 or 7 is attached incorrectly or the substrate 5 is placed incorrectly.

  The sensor 81 acquires information necessary for controlling the screen printing apparatus 100, such as a sensor for measuring environmental conditions such as a temperature sensor and a humidity sensor, a position sensor, and a pressure sensor. The substrate carrying motor 82 is a drive source for driving a belt conveyor included in the carrying conveyor 22. By driving the substrate transport motor 82, the transport conveyor 22 transports the substrate 5 in the X direction.

  The work table drive unit 83 is a drive source for the substrate work table 2, and includes an X-axis servo motor 831, a Y-axis servo motor 832, and a Z-axis servo motor 833. The X-axis servo motor 831 corresponds to the above-mentioned X-axis moving mechanism 51 that moves the clamp unit 23 in the X direction. The Y-axis servo motor 832 corresponds to the above-mentioned servo motor 13 that moves the movable table 21 in the Y direction. The Z-axis servo motor 833 is a drive source of the lifting mechanism 53b of the support mechanism 53 that lifts and lowers the substrate.

  The cleaning drive unit 84 is a drive source of the cleaning unit 25 and includes a mechanism for generating a suction force on the suction nozzle of the cleaning head, a mechanism for moving the cleaning head up and down, and the like. The movement of the cleaning unit 25 in the Y direction depends on the Y-axis servo motor 832.

  The clamp drive unit 85 is a drive source that moves the movable clamp unit 52b of the clamp unit 23 between a position where it is pressed against the side of the substrate 5 to clamp the substrate 5 and a position where the clamp is released. .. The clamp drive unit 85 is, for example, an air cylinder.

  The mask driving unit 86 moves the small component mask 6 on the first printing table 30A and the large component mask 7 on the second printing table 30B in the Y and Z directions, respectively, and rotates them around the Z axis. Is a drive unit for. The mask driving unit 86 corresponds to the mask lifting mechanism 32 and the mask driving mechanism 33 described above.

  The squeegee drive unit 87 is a drive source that moves the movable beams 42 of the first and second squeegee units 4A and 4B in the Y direction, and includes the squeegee shaft motor 45 described above. The squeegee drive unit 87 further includes an elevating mechanism that elevates and lowers the squeegee 41, and a squeegee angle changing mechanism that adjusts the tilt angle of the squeegee 41.

  The control unit 90 includes a microcomputer and the like, and controls the operation of the screen printing apparatus 100, that is, the above-described first and second print processing operations in a centralized manner. The control unit 90 functionally executes a predetermined program so that the imaging control unit 91, the image processing unit 92, the arithmetic processing unit 93 (determination unit), the conveyance control unit 94, the work table control unit 95, and the cleaning control are functionally performed. The unit 96, the clamp control unit 97, the mask control unit 98, and the squeegee control unit 99 are operated so as to have them.

  The imaging control unit 91 controls the imaging operations of the board recognition camera 15 and the mask recognition camera 24. Specifically, the imaging control unit 91 has an operation of causing the board recognition camera 15 to take an image of the board recognition mark for the recognition processing of the board 5, and the mask recognition camera 24 is attached to the small component mask 6 and the large component mask 7. The operation of imaging the mask recognition mark is executed. In addition to this, in the present embodiment, the image pickup control unit 91 causes the board recognition camera 15 to pick up an image of a designated point of the substrate 5 that is designated in advance as a predicted solder paste attachment position, or a designated point of the mask 6 or the mask 7. Is performed by the mask recognition camera 24.

  The image processing unit 92 performs image processing such as edge detection processing for the shape recognition of the board recognition mark and the mask recognition mark on the image data acquired by the board recognition camera 15 and the mask recognition camera 24. Further, the image processing unit 92 performs image processing for extracting the solder paste adhered portion on the image data obtained by the board recognition camera 15 and the mask recognition camera 24 capturing the designated points.

  The arithmetic processing unit 93 performs various arithmetic processing necessary for controlling the screen printing apparatus 100, situation recognition based on various information acquired by the sensor 81, arithmetic processing for changing control conditions, and the like. In addition to this, the arithmetic processing unit 93 determines whether or not a solder paste (viscous material) is present at the designated point based on the image processing result of the image data of the designated point by the image processing unit 92. I do.

  The transport controller 94 controls the substrate transport motor 82 to control the substrate transport operation of the substrate 5 by the belt conveyor of the transport conveyor 22. The work table control unit 95 controls the work table drive unit 83 to control the movement operation of the substrate work table 2, the movement of the clamp unit 23, and the raising / lowering operation, and position the substrate 5 on the masks 6 and 7. Execute the operation.

  The cleaning control unit 96 controls the cleaning drive unit 84 to cause the cleaning unit 25 to execute a cleaning operation of wiping the back surfaces of the masks 6 and 7. In the present embodiment, in addition to the predetermined regular cleaning operation, when the arithmetic processing unit 93 determines that the solder paste is present at the specified point, the cleaning control unit 96 cleans the back surface of the large component mask 7. Perform an action.

  The clamp control section 97 controls the moving operation of the moving clamp section 52b of the clamp unit 23 by controlling the clamp drive section 85. When the clamp drive unit 85 is an air cylinder, the clamp control unit 97 controls a regulator attached to the air cylinder to control the thrust force of the air cylinder according to a predetermined substrate pressing parameter.

  The mask control unit 98 controls the mask driving unit 86 to perform horizontal movement and vertical movement for aligning the small component mask 6 and the large component mask 7 with respect to the substrate. The squeegee control unit 99 controls the squeegee drive unit 87 to execute the first and second print processing operations by the squeegee 41 of the first and second squeegee units 4A and 4B, respectively.

[First Embodiment of Solder Detection Processing]
FIG. 13 is a flowchart showing the first embodiment of the solder detection processing by the screen printing apparatus 100 by imaging the designated point. In the first embodiment, it is assumed that the small-part mask 6 is attached to the mask fixing member 31 of the first screen printing unit 3A in a state of being inverted by 180 ° with respect to the normal direction, thereby causing a printing defect. The designated point for checking whether or not the solder paste is present is a specific position on the back surface of the large component mask 7 (second mask), and imaging is performed after the second printing process.

  Assuming the above-mentioned print failure, the control unit 90 sets a designated point at a specific position on the back surface of the large component mask 7, and teaches this setting to the imaging control unit 91 (step S1). When the first printing process is performed by the first screen printing unit 3A using the small component mask 6 in which the mounting direction is inverted by 180 °, the small pattern Sd1 is inverted by 180 ° with respect to the regular position on the substrate 5. It will be printed in the regular position. Then, when the mask 7 for a large component is plate-matched on the substrate 5 for the second printing process, it can be expected that the solder paste will be attached to the portion facing the irregular position (the estimated attachment position). ). Such a predicted adhesion position is the specific position, and a designated point is set at the position.

  Then, the printing process on the substrate 5 is executed. The transport control unit 94 operates the transport conveyor 22 to take in the substrate 5 from the loader LD, and the work table control unit 95 operates the substrate work table 2, so that the substrate 5 is carried into the first screen printing unit 3A. (Step S2).

  Next, the clamp control unit 97, the mask control unit 98, and the squeegee control unit 99 control the clamp drive unit 85, the mask drive unit 86, and the squeegee drive unit 87, respectively, so that the first screen printing unit 3A displays the substrate 5 on the substrate 5. The first printing process is performed (step S3, see also FIG. 6). As a result, the small pattern Sd1 corresponding to the small pattern opening 61 of the small component mask 6 is printed on the substrate 5. Here, if the mask 6 for small components is properly attached, the small pattern Sd1 is printed at the regular position on the substrate 5 (see FIG. 7). On the other hand, if the small component mask 6 is attached 180 degrees upside down, the small pattern Sd1 is printed at an irregular position on the substrate 5 (see FIG. 11).

  Then, the work table control unit 95 operates the substrate work table 2 to move the substrate 5 to the second screen printing unit 3B (step S4). Then, the clamp control unit 97, the mask control unit 98, and the squeegee control unit 99 control the clamp drive unit 85, the mask drive unit 86, and the squeegee drive unit 87, respectively, so that the second screen printing unit 3 </ b> B prints the substrate 5 on the substrate 5. Two printing processes are performed (step S5, see also FIG. 9). As a result, the large pattern Sd2 corresponding to the large pattern opening 71 of the large component mask 7 is printed on the substrate 5 in addition to the small pattern Sd1 (see FIG. 10).

  If the first printing process is executed with the small component mask 6 that is properly installed, the small pattern Sd1 in the second printing process is the relief recess 72 of the large component mask 7 as shown in FIG. Housed in. On the other hand, if the first printing process is executed by the small component mask 6 attached by reversing 180 °, the small pattern Sd1 is not accommodated in the escape recess 72. Not only that, the solder paste of the small pattern Sd1 adheres to the designated point set in step S1 of the mask 7 for large parts.

  After the second printing process, the image capturing control unit 91 causes the mask recognition camera 24 to capture an image of the designated point on the back surface of the large component mask 7 (step S6). The image data acquired by the image pickup is sent to the image processing unit 92, and image processing for extracting the solder paste adhered portion in the image is executed. Then, based on the image processing result, the arithmetic processing unit 93 determines whether or not the solder paste is present at the designated point (step S7).

  If it is determined that the solder paste does not exist at the designated point (NO in step S7), it means that the regular first printing process has been performed on the substrate 5. In this case, the control unit 90 confirms whether or not there is the subsequent substrate 5 to be subjected to the print processing (step S8), and if the subsequent substrate 5 is present (YES in step S8), proceeds to step S2. Return and repeat the process.

  On the other hand, when it is determined that the solder paste is present at the designated point (YES in step S7), a mounting error of the small component mask 6 has occurred, and the regular first printing process has not been performed on the substrate 5. become. In this case, the control unit 90 causes the cleaning control unit 96 to execute the cleaning operation. The cleaning control unit 96 controls the cleaning driving unit 84 to execute an operation of cleaning the back surface of the large-sized component mask 7 (step S9). By this cleaning operation, the solder paste attached to the back surface of the mask 7 for large components is removed.

  Further, the control unit 90 causes a display panel (not shown) or a sound source to notify the occurrence of a print defect, and causes the screen printing apparatus 100 to stop due to an error (step S10). This is to notify the operator that a printing failure has occurred on the substrate 5 on which the first and second printing processes have been performed immediately before, and to allow the operator to take out the substrate from the screen printing apparatus 100. .. After the error processing, the screen printing apparatus 100 is restarted, and the process returns to step S2 to continue the processing.

[Second Embodiment of Solder Detection Processing]
FIG. 14 is a flowchart showing a second embodiment of the solder detection processing by the screen printing apparatus 100 by imaging the designated point. In the second embodiment, an example in which an error in mounting the small component mask 6 similar to that in the first embodiment is found by imaging a specific position of the substrate 5 will be described. Unlike the first embodiment, the image capturing timing is after the execution of the first print processing and before the execution of the second print processing.

  Assuming the above printing failure, the control unit 90 sets a designated point at a specific position on the surface of the substrate 5, and teaches this setting to the imaging control unit 91 (step S11). As described above, when the first printing process is performed using the small component mask 6 in which the mounting direction is reversed by 180 °, the small pattern Sd1 is printed at the non-regular position on the substrate 5 that is reversed by 180 ° with respect to the regular position. To be done. This non-regular position is a position to which the solder paste cannot adhere in the regular first printing process. The control unit 90 sets the non-regular position (specific position) as the expected adhesion position to the designated point.

  Then, the printing process on the substrate 5 is executed. The substrate 5 is carried into the first screen printing unit 3A (step S12), and the first printing process is performed on the substrate 5 (step S13). As a result, the small pattern Sd1 is printed on the substrate 5. If the small component mask 6 is properly attached, the small pattern Sd1 is printed at the regular position on the substrate 5, and if it is inverted 180 ° and attached, the small pattern Sd1 is printed at the irregular position on the substrate 5. To be done. After the first printing process, the substrate 5 is moved to the second screen printing unit 3B (step S14).

  After that, the imaging control unit 91 causes the substrate recognition camera 15 provided in the second screen printing unit 3B to image the designated point of the substrate 5 moved to the second screen printing unit 3B (step S15). Based on the image of the designated point acquired by this imaging, the arithmetic processing unit 93 determines whether or not the solder paste is present at the designated point (step S16).

  When it is determined that the solder paste does not exist at the designated point (NO in step S16), it means that the regular first printing process has been performed on the substrate 5. In this case, the control unit 90 causes the second screen printing unit 3B to execute the second printing process on the substrate 5 (step S17). After that, the control unit 90 confirms whether or not there is the subsequent substrate 5 to be subjected to the print processing (step S18). If the subsequent substrate 5 is present (YES in step S18), the process proceeds to step S12. Return and repeat the process.

  On the other hand, when it is determined that the solder paste is present at the designated point (YES in step S18), an attachment error of the small component mask 6 has occurred, and the regular first printing process has not been performed on the substrate 5. become. In this case, the control unit 90 stops the execution of the second print processing. That is, the control unit 90 notifies the occurrence of a print defect and causes the screen printing apparatus 100 to stop due to an error (step S19).

  According to the second embodiment, it is possible to detect a print defect before the second printing process is performed on the substrate 5. Therefore, there is an advantage that it is possible to avoid performing the unnecessary second printing process on the already defective substrate 5, and it is possible to prevent the solder paste from adhering to the large component mask 7.

[Third Embodiment of Solder Detection Processing]
FIG. 15 is a flowchart showing a third embodiment of the solder detection processing by the screen printing apparatus 100 by imaging the designated point. The third embodiment is a mode in which a specific position of the substrate 5 is imaged similarly to the second embodiment, but when the first printing process is executed in a state where the small component mask 6 is properly attached, An example is shown in which a regular position where the solder paste is normally printed is imaged as the specific position (adhesion planned position). Contrary to the second embodiment, in the third embodiment, the normal position is set as the designated point, and the occurrence of printing failure is detected by the absence of solder paste at the designated point.

  The control unit 90 sets the designated point at the regular position where the small pattern Sd1 is printed when the regular first printing process is performed, and teaches this setting to the imaging control unit 91 (step S21). The substrate 5 is carried into the first screen printing unit 3A (step S22), and the first printing process is performed on the substrate 5 (step S23).

  After that, the imaging control unit 91 causes the substrate recognition camera 15 provided in the first screen printing unit 3A to image the designated point of the substrate 5 after the first printing process (step S24). Based on the image of the designated point acquired by this imaging, the arithmetic processing unit 93 determines whether or not the solder paste is present at the designated point (step S25).

  If it is determined that the solder paste is present at the designated point (YES in step S25), it means that the regular first printing process has been performed on the substrate 5. In this case, the control unit 90 moves the substrate 5 to the second screen printing unit 3B (step S26), and further causes the second screen printing unit 3B to execute the second printing process on the substrate 5 (step S27). After that, the control unit 90 confirms whether or not the subsequent substrate 5 to be subjected to the printing process is present (step S28). If the subsequent substrate 5 is present (YES in step S28), the process proceeds to step S22. Return and repeat the process.

  On the other hand, when it is determined that the solder paste does not exist at the designated point (NO in step S25), an attachment error of the small component mask 6 occurs, and the regular first printing process is not performed on the substrate 5. It will be. In this case, the control unit 90 stops the conveyance of the substrate 5 to the second screen printing unit 3B to stop the execution of the second printing process. That is, the control unit 90 notifies the occurrence of printing failure and causes the screen printing apparatus 100 to stop due to an error (step S29). As a result, the transfer of the substrate 5 to the second screen printing unit 3B by the substrate work table 2 is stopped. According to the third embodiment, similarly to the second embodiment, there is an advantage that unnecessary use of the second printing process can be avoided.

[Fourth Embodiment of Solder Detection Processing]
FIG. 16 is a schematic diagram for explaining the fourth embodiment of the solder detection process by imaging the designated point by the screen printing device. The screen printing apparatus shown in FIG. 16 has an example in which the first screen printing unit 3C and the second screen printing unit 3D are independent of each other, and the connection conveyor 22A (substrate transfer unit) is arranged between them. ing.

  The first screen printing unit 3C includes a small component mask 6, a substrate recognition camera 15C and a mask recognition camera 24C, and the second screen printing unit 3D includes a large component mask 7, a substrate recognition camera 15D and a mask recognition camera 24D. It is equipped with. 22 A of connection conveyors convey the board | substrate 5 which completed the 1st printing process by the 1st screen printing part 3C to the 2nd screen printing part 3D. Since the connecting conveyor 22A conveys the substrate 5 in an exposed state, the operator can access the substrate 5 on the connecting conveyor 22A.

  According to the screen printing apparatus described above, the operator can take out the substrate 5 that has been conveyed through the connection conveyor 22A after the first printing process is completed. For example, the operator may take out the substrate 5 by stopping the connecting conveyor 22A to check the finish of the first printing process. When the substrate 5 is returned to the connecting conveyor 22A, the mounting direction of the substrate 5 may be mistaken by 180 °. In this case, even if the correct first printing process is performed on the substrate 5, printing failure will occur in the second printing process in the second screen printing unit 3D. In FIG. 16, the mark “A” on the substrate 5 is reversed between the inside of the first screen printing unit 3C and the connecting conveyor 22A, which schematically shows the case where the above-mentioned mistake has occurred.

  As the method of detecting a printing defect in this case, the above-described first to third embodiments can be applied. That is, the detection method according to the first embodiment is a method of capturing an image of the large component mask 7 of the second screen printing unit 3D after the second printing process in the second screen printing unit 3D. Specifically, after the second printing process is performed on the substrate carried in from the connecting conveyor 22A to the second screen printing unit 3D, the mask recognition camera 24D causes the mask 7 for large components to be imaged. When a return error of the substrate 5 on the connecting conveyor 22A occurs, the solder paste adheres to the designated point on the large-sized component mask 7. Therefore, a print defect can be detected.

  The method of detecting a printing defect according to the second and third embodiments is performed by the board recognition camera 15D before the second printing process is performed on the board carried into the second screen printing unit 3D from the connection conveyor 22A. Is a method of imaging. The point to be imaged is a designated point which is the previously designated non-regular position (second embodiment) or regular position (third embodiment) that is designated in advance on the surface of the substrate 5. By picking up images of these designated points, it is possible to detect a print defect due to the return error.

[Fifth Embodiment of Solder Detection Processing]
FIG. 17 is a schematic diagram for explaining the fifth embodiment of the solder detection processing by the screen printing apparatus by imaging the designated point. Similar to FIG. 16, the screen printing apparatus shown in FIG. 17 has a device configuration in which the first screen printing unit 3C and the second screen printing unit 3D are independent of each other, and the connection conveyor 22A is arranged between them.

  In the first screen printing unit 3C, printing failure may occur even if there is no mistake in mounting the small component mask 6 in the wrong mounting direction. For example, this is a case where the mask 6 for small components and the substrate 5 are matched for some reason. As shown in FIG. 18A, it is assumed that the first printing process is performed in a state where the small component mask 6 is misaligned with the substrate 5 and the plates are aligned. In this case, a print misalignment occurs in which the small pattern Sd1 is printed at a position shifted by the mask misalignment with respect to the original print position on the substrate 5. In this case, as shown in FIG. 18B, in the second printing process, the small pattern Sd1 may not be accommodated in the escape recess 72 of the large component mask 7, which may result in defective printing.

  The above-described first to third embodiments can also be applied as a method of detecting a print defect in this case. That is, the detection method according to the first embodiment is a method of capturing an image of the large component mask 7 of the second screen printing unit 3D after the second printing process in the second screen printing unit 3D. Specifically, after the second printing process is performed on the substrate carried in from the connecting conveyor 22A to the second screen printing unit 3D, the mask recognition camera 24D causes the mask 7 for large components to be imaged. When a large print displacement of the small pattern Sd1 occurs in the first printing process, the solder paste adheres to the periphery of the large pattern opening 71 of the large component mask 7. Therefore, a printing defect can be detected by performing imaging with the periphery of the large pattern opening 71 as the designated point.

  The method of detecting a printing defect according to the second and third embodiments is performed by the board recognition camera 15D before the second printing process is performed on the board carried into the second screen printing unit 3D from the connection conveyor 22A. Is a method of imaging. The imaged point is the printing position of the small pattern Sd1 on the surface of the substrate 5. By causing the board recognition camera 15D to capture an image with this printing position as the designated point, it is possible to detect a printing defect due to the printing misalignment.

  Instead of this, the print position of the small pattern Sd1 on the substrate 5 may be imaged by the substrate recognition camera 15C of the first screen printing unit 3C. That is, the substrate 5 after the first printing process is finished is imaged inside the first screen printing unit 3C. Then, when the printing deviation of the small pattern Sd1 is detected by the imaging, the board from the first screen printing unit 3C to the second screen printing unit 3D by the connecting conveyor 22A is used to stop the execution of the second printing process. The conveyance of 5 is stopped. Also according to this aspect, it is possible to detect the print failure in the same manner.

100 screen printing device 15 board recognition camera (imaging unit)
2 Substrate work table 21 Movable table 21
22 Conveyor Conveyor 22A Connection Conveyor (Substrate Conveyor)
24 Mask recognition camera (imaging unit)
25 Cleaning unit (cleaning section)
3A, 3C 1st screen printing part 3B, 3D 2nd screen printing part 30A 1st printing table 30B 2nd printing table 4A 1st squeegee unit (1st printing part)
4B Second squeegee unit (second printing section)
5 board 5
6 Mask for small parts (first mask)
61 Small pattern opening (first pattern opening)
7 Mask for large parts (second mask)
71 Large pattern opening (second pattern opening)
72 escape recess 90 control unit (print control unit)
93 Arithmetic processing unit (determination unit)

Claims (5)

A first screen printing unit including a first mask and a first printing unit, which performs a first printing process of screen-printing a viscous material on a substrate;
A second screen printing unit that includes a second mask and a second printing unit and that performs a second printing process of screen-printing a viscous material on the substrate that has been subjected to the first printing process;
An image capturing unit that captures an image of a designated point that has been designated in advance as the predicted adhesion position of the viscous material due to the first printing process or the second printing process;
A determination unit that determines whether or not the viscous material exists at the designated point based on the image acquired by the imaging unit;
In a screen printing device including
The designated point is a specific position of the substrate on which the first printing process is performed,
The image capturing unit captures an image of a specific position of the substrate after the first printing process,
A print control unit that controls operations of the first print processing and the second print processing,
The specific position of the substrate is a predetermined non-regular position to which the viscous material cannot adhere in the regular first printing process,
The screen printing apparatus, wherein the printing control unit stops the execution of the second printing process when the determination unit determines that the viscous material is present at the non-regular position. A first screen printing unit including a first mask and a first printing unit, which performs a first printing process of screen-printing a viscous material on a substrate;
A second screen printing unit that includes a second mask and a second printing unit and that performs a second printing process of screen-printing a viscous material on the substrate that has been subjected to the first printing process;
An image capturing unit that captures an image of a designated point that has been designated in advance as the predicted adhesion position of the viscous material due to the first printing process or the second printing process;
A determination unit that determines whether or not the viscous material exists at the designated point based on the image acquired by the imaging unit;
In a screen printing device including
The designated point is a specific position of the substrate on which the first printing process is performed,
The image capturing unit captures an image of a specific position of the substrate after the first printing process,
A print control unit that controls operations of the first print processing and the second print processing,
The specific position of the substrate is a predetermined regular position to which the viscous material adheres in the regular first printing process,
The screen printing apparatus , wherein the print control unit causes the execution of the second printing process to be stopped when the determination unit determines that the viscous material does not exist at the regular position . The screen printing apparatus according to claim 1 ,
Further comprising a substrate transfer unit that transfers the substrate from the first screen printing unit to the second screen printing unit,
The image pickup unit is arranged in the first screen printing unit,
A screen printing apparatus, wherein the printing control unit stops the transportation of the substrate by the substrate transportation unit from the first screen printing unit to the second screen printing unit in order to stop the execution of the second printing process. .. The screen printing apparatus according to any one of claims 1 to 3 ,
The first mask has a predetermined first thickness, and has a predetermined first pattern opening,
The second mask has a second thickness larger than the first thickness, and includes a predetermined second pattern opening and a relief recess provided at a position corresponding to the first pattern opening. .. The screen printing device according to any one of claims 1 to 4 ,
The first and second screen printing units each have an independent device configuration,
The screen printing apparatus further comprises a connection conveyor that is disposed between the first screen printing unit and the second screen printing unit and that conveys the substrate in a state accessible by an operator.

Images