JP6748844B2 - Screen printing method - Google Patents

Description

The present invention relates to a screen printing method in which a squeegee is slid on a mask to print a paste on an object to be printed through an opening of the mask.

The screen printing apparatus prints the paste on the substrate through the openings of the mask by sliding the squeegee on the mask brought into contact with the substrate as the printing object and scraping the paste supplied onto the mask with the squeegee. Then, after such a printing process, an inspection device provided on the downstream side of the screen printing device inspects whether or not the paste is normally printed on each electrode of the substrate. In the inspection of the printed state of this board (called printing inspection), if a shortage of the printing amount such as "chip" or "untransferred" of the paste on the electrode is detected, the paste in the opening of the mask remains and clogging occurs. Is likely to have caused. For this reason, the following Patent Document 1 discloses a technique of wiping off the paste adhering to the lower surface of the mask by a mask cleaning device to clean it when a print amount shortage is detected in a print inspection (for example, the following). Patent Document 1).

JP 2001-47600 A

However, when the printed amount is insufficient on the substrate after printing, the cause may be clogging of the mask or improper printing conditions. In this respect, in the above-mentioned conventional screen printing apparatus, since the mask cleaning is always executed when the shortage of the printing amount is detected, as a result, when the cause of the printing defect is not the clogging of the mask, There is a problem in that there is a risk of loss of time and a decrease in productivity.

Therefore, it is an object of the present invention to provide a screen printing method capable of preventing a decrease in productivity due to performing useless mask cleaning.

The screen printing method of the present invention, by sliding the squeegee on the mask in contact with the print object, scraping the paste supplied on the mask with the squeegee to the print object through the opening of the mask. A printing step for printing the paste, a printing amount inspection step for inspecting whether or not a shortage of the printing amount of the paste has occurred on the printing object on which the paste has been printed in the printing step, and the printing in the printing amount inspection step A clogging inspection step for inspecting whether or not a clogging occurs in the opening of the mask when it is detected that the printing amount of the paste is insufficient on the object, and the opening of the mask in the clogging inspection step. If the mask cleaning step and see contains to clean the mask if it is detected that the clogging has occurred, and detects that the clogging in the opening of the mask in the clogging checking step does not occur in, It is determined whether or not the pause duration of the printing process exceeds a preset reference time, and the printing condition is changed according to the determination result .

According to the present invention, it is possible to prevent a decrease in productivity due to performing unnecessary mask cleaning.

Configuration diagram of a printing system in an embodiment of the present invention 1 is a perspective view of a screen printing apparatus included in a printing system according to an embodiment of the present invention. A side view of a screen printing apparatus included in a printing system according to an embodiment of the present invention 1 is a perspective view of a part of a screen printing apparatus included in a printing system according to an embodiment of the present invention. 1 is a block diagram showing a control system of a screen printing apparatus included in a printing system according to an embodiment of the present invention. 1 is a perspective view of an inspection device included in a printing system according to an embodiment of the present invention. 1 is a block diagram showing a control system of an inspection device included in a printing system according to an embodiment of the present invention. A flowchart of a main routine showing a procedure of screen printing work performed by the printing system according to the embodiment of the present invention. A flowchart of a subroutine showing a procedure of screen printing work performed by the printing system according to the embodiment of the present invention. (A) (b) Operation explanatory drawing of the screen printing work which the screen printing apparatus with which the printing system in one embodiment of this invention is equipped performs (A) (b) Operation explanatory drawing of mask cleaning work which the screen printing apparatus of the printing system in one embodiment of this invention performs The flowchart of the modification of the subroutine which shows the procedure of the screen printing work which the printing system in one embodiment of this invention performs.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a printing system 1 according to an embodiment of the present invention. The printing system 1 uses a printed circuit board (hereinafter, referred to as a substrate 2) for forming an electronic circuit as a print target, and a screen printing apparatus 1A that carries in the printed circuit board and prints a paste Pst such as solder on the electrode 2d. The inspection device 1B receives the substrate 2 from the screen printing device 1A and inspects the paste Pst printed on the substrate 2. Here, for convenience of description, the left-right direction viewed from the operator OP is the X-axis direction, the left side is the upstream process side, and the right side is the downstream process side. Further, the front-back direction viewed from the operator OP is the Y-axis direction, and the up-down direction is the Z-axis direction.

2, FIG. 3, and FIG. 4, the screen printing apparatus 1A includes a carry-in conveyor 12, a substrate lifting mechanism 13 and a carry-out conveyor 14 on a base 11, and a mask 15 and a camera unit above the substrate lifting mechanism 13. 16, a print head 17, and a mask cleaner 18. The substrate elevating mechanism 13 is provided at the center of the base 11, and the carry-in conveyor 12 is provided on the left side of the substrate elevating mechanism 13. The carry-out conveyor 14 is provided on the right side of the substrate elevating mechanism 13.

3 and 4, the substrate elevating mechanism 13 includes a substrate holding portion 21 and an elevating mechanism portion 22. The substrate holding unit 21 includes a positioning conveyor 31, a lower receiving unit 32, and a pair of front and rear clampers 33. The positioning conveyor 31 positions the substrate 2 received from the carry-in conveyor 12 at a predetermined clamp position. The lower receiving portion 32 supports the substrate 2 positioned at the clamp position from below. The clamper 33 clamps and holds the substrate 2 supported by the lower receiving portion 32 from the side (Y-axis direction). The elevating mechanism unit 22 is composed of an XYθ table in which a plurality of table members are stacked in multiple stages, and moves the substrate holding unit 21 in the horizontal plane and in the vertical direction.

In FIGS. 1, 2 and 3, the mask 15 is made of a rectangular flat plate-shaped metal member that extends and extends in the XY plane. The outer periphery of the mask 15 is supported by the frame member 15W. A large number of openings 15H are provided in the center of the mask 15 (FIGS. 1 and 4). These openings 15H are provided corresponding to the electrodes 2d of the substrate 2.

In FIG. 3, the camera unit 16 includes an upper imaging section 16a having an imaging field of view directed upward and a lower imaging section 16b having an imaging field of view directed downward. The camera unit 16 is driven by a camera unit moving mechanism 16K (FIG. 2) using a ball screw mechanism as an actuator to move in the space between the substrate elevating mechanism 13 and the mask 15 in the XY plane.

2 and 3, the print head 17 includes a moving base 41, two squeegee lifting cylinders 42, and two squeegees 43. The moving base 41 extends in the X-axis direction and is driven by the print head moving mechanism 17K including a ball screw mechanism to move the mask 15 above the mask 15 in the Y-axis direction. The two squeegee lifting cylinders 42 are provided on the upper surface of the moving base 41 side by side in the Y-axis direction. Each squeegee lifting cylinder 42 has a piston rod 42R protruding below the moving base 41, and a squeegee 43 is attached to the lower end thereof (FIG. 3).

The squeegee 43 is made of a "spa"-shaped member extending in the X-axis direction. When the two squeegees 43 are viewed from the X-axis direction, the two squeegees 43 extend obliquely so as to spread downward (FIGS. 2 and 3). The two squeegees 43 have surfaces facing each other that scrape the paste Pst, and will be referred to as scraping surfaces in the following description. The surface opposite to the scraping surface is called the back surface. When the squeegee lifting cylinder 42 operates the piston rod 42R in the vertical direction, the squeegee 43 moves up and down below the moving base 41 with respect to the moving base 41.

In FIG. 3, the mask cleaner 18 exposes the paper member 18P on the upper surface, and is moved in the Y-axis direction integrally with the camera unit 16 by the camera unit moving mechanism 16K. The mask cleaner 18 brings the exposed surface of the paper member 18P into contact with the lower surface of the mask 15 when the mask 15 is not in contact with the substrate 2 and is moved in the Y-axis direction by the camera unit moving mechanism 16K. The paste Pst adhering to the lower surface of the is wiped off for cleaning. The paper member 18P is incorporated in the mask cleaner 18 and is wound by a motor (not shown) to update the exposed surface.

In FIG. 5, the printing apparatus control unit 50 included in the screen printing apparatus 1</b>A includes a carry-in (carry-in) operation of the board 2 by the carry-in conveyor 12, a holding and moving operation of the board 2 by the board elevating mechanism 13, and a board 2 by the carry-out conveyor 14. Each control of the carrying (unloading) operation is performed. In addition, the printing device control unit 50 moves the camera unit 16 by the camera unit moving mechanism 16K, the imaging operation of the camera unit 16, the moving operation of the print head 17 by the print head moving mechanism 17K, and the squeegee 43 of the squeegee lifting cylinder 42. Each control such as the lifting operation and the winding operation of the paper member 18P in the mask cleaner 18 is performed. The camera unit 16 transmits the image data obtained by imaging to the printing device control unit 50, and the printing device control unit 50 performs image recognition based on the received image data.

In FIG. 5, a touch panel 51 as an input/output device is connected to the printing device control unit 50. The touch panel 51 functions as an input device for the worker OP to make a required input to the printing device control unit 50, and the printing device control unit 50 also displays the status of the screen printing device 1A to the worker OP or informs the worker OP. It functions as an output device that gives work instructions.

In FIG. 6, the inspection apparatus 1</b>B includes a conveyor 62 on the inspection table 61, and an inspection camera 63 above the conveyor 62. The inspection camera 63 is attached to an inspection camera moving mechanism 64 provided on the inspection table 61. The inspection camera moving mechanism 64 is composed of an orthogonal coordinate table, and moves the inspection camera 63 in the horizontal direction in the area above the inspection table 61.

In FIG. 7, the inspection device control unit 70 included in the inspection device 1B controls each of the transfer operation of the substrate 2 by the transfer conveyor 62, the movement operation of the inspection camera 63 by the inspection camera moving mechanism 64, the imaging operation of the inspection camera 63, and the like. To do. The inspection device control unit 70 can exchange signals and data with the printing device control unit 50 (see also FIG. 5).

The inspection device control unit 70 operates the inspection camera moving mechanism 64 in response to the instruction from the printing device control unit 50, and causes the inspection camera 63 to image the paste Pst printed on the substrate 2. The inspection device control unit 70 transmits the obtained image data to the printing device control unit 50. The printing device control unit 50 that has received the image data performs image recognition and detects the printing state of the paste Pst for each electrode 2d.

Next, an execution procedure of a screen printing operation (screen printing method) for performing screen printing on the substrate 2 by the printing system 1 having the above configuration will be described with reference to the flowcharts shown in FIGS. 8 and 9. When the screen printing work is performed by the printing system 1, the operator OP performs a work start operation from the touch panel 51 included in the screen printing apparatus 1A. When the operator OP performs a work start operation from the touch panel 51, each unit of the screen printing apparatus 1A controlled by the printing apparatus control unit 50 executes the printing process by steps ST1 to ST6 in the flowchart of the main routine shown in FIG. To do.

In the printing process, first, the carry-in conveyor 12 operates to receive the substrate 2 supplied from the outside. Then, the substrate 2 is transferred to the substrate holder 21. Upon receiving the substrate 2 by the positioning conveyor 31, the substrate holding unit 21 conveys the substrate 2 to position it at a predetermined clamp position, supports the substrate 2 from below by the lower receiving unit 32, and clamps it by the clamper 33. (Substrate carry-in step of step ST1).

When the substrate holder 21 holds the substrate 2, the camera unit moving mechanism 16K operates to move the camera unit 16 between the substrate 2 and the mask 15. As a result, the upper imaging unit 16a of the camera unit 16 images the mask side mark 15m (FIG. 2) provided on the mask 15 from below, and the lower imaging unit 16b views the substrate side mark 2m (FIG. 4) of the substrate 2 from above. Take an image. After capturing the mask side mark 15m and the board side mark 2m, the camera unit 16 transmits the image data to the printing apparatus controller 50. The printing apparatus control unit 50 that receives the image data performs image recognition and calculates the positions of the mask side mark 15m and the substrate side mark 2m. When the positions of the mask-side mark 15m and the substrate-side mark 2m are calculated, the substrate lifting mechanism 13 moves the substrate holding unit 21 (that is, the substrate 2) so that the mask-side mark 15m and the substrate-side mark 2m can be seen in a plan view. They are matched (positioning process of step ST2).

When the mask-side mark 15m and the substrate-side mark 2m coincide with each other in a plan view, the substrate elevating mechanism 13 raises the substrate holding unit 21 (that is, the substrate 2) to bring the upper surface of the substrate 2 into contact with the lower surface of the mask 15 (see FIG. 10(a), arrow A) shown in the figure. As a result, the electrode 2d of the substrate 2 is exposed on the upper surface of the mask 15 through the corresponding opening 15H (contact step of step ST3).

When the substrate 2 comes into contact with the mask 15, one squeegee lifting cylinder 42 lowers the squeegee 43 to bring it into contact with the mask 15. When the squeegee 43 contacts the mask 15, the print head moving mechanism 17K moves the moving base 41 in the Y-axis direction. The moving direction of the squeegee 43 is from the front to the rear for the front squeegee 43 (arrow B shown in FIG. 10B), and the direction of the rear squeegee 43 is from the rear to the front. Since the squeegee 43 sliding on the mask 15 scrapes the paste Pst by the scraping surface, the paste Pst is filled in each opening 15H of the mask 15 through which the squeegee 43 has passed (squeezing step of step ST4).

When the filling of the paste Pst into the opening 15H of the mask 15 is completed as described above, the substrate elevating mechanism 13 lowers the substrate holding unit 21 by the elevating mechanism unit 22 to separate the substrate 2 from the mask 15 and separate the plate. To do. As a result, the paste Pst filled in the openings 15H of the mask 15 is transferred onto the respective electrodes 2d of the substrate 2 (step ST5, plate separation step).

The substrate elevating mechanism 13 opens the clamper 33 of the substrate holding unit 21 after releasing the plate to release the holding of the substrate 2 and operates the positioning conveyor 31 to transfer the substrate 2 to the unloading conveyor 14. The carry-out conveyor 14 carries out the received substrate 2 to the inspection device 1B on the downstream process side (substrate carry-out process of step ST6).

After the screen printing apparatus 1A carries out the substrate 2 to the inspection apparatus 1B, the inspection apparatus 1B carries in the substrate 2 by the transport conveyor 62 and positions it at a predetermined working position. Then, the inspection camera moving mechanism 64 moves the inspection camera 63 above the substrate 2, and the inspection camera 63 images the paste Pst printed on each electrode 2d of the substrate 2. The inspection device control unit 70 transmits the image data of the paste Pst for each electrode 2d of the substrate 2 obtained by imaging to the printing device control unit 50.

The screen printing apparatus 1A receives the above-mentioned data (image data of the paste Pst for each electrode 2d of the substrate 2) sent from the inspection apparatus 1B after the printing process including the steps ST1 to ST6 is completed (data of step ST7). Receiving process). Then, the following print inspection handling process is executed (step ST8, a subroutine shown in FIG. 9).

In the print inspection handling process of step ST8, the printing device controller 50 first determines whether or not there is an abnormality in the printing state of the paste Pst on each electrode 2d of the substrate 2 based on the image data sent from the inspection device 1B. It is determined (step ST11). Then, as a result, if there is no abnormality, the process returns to the main routine, but if it is determined that there is an abnormality, whether or not there is a print amount shortage such as “missing” or “untransferred” in the electrode 2d. Is determined (print amount inspection step of step ST12). Then, when it is determined that the printing amount is insufficient, the clogging inspection is executed (the clogging inspection process of step ST13).

When it is determined in step ST11 that the printing state of the paste Pst is abnormal, the printing device control unit 50 outputs a board discard command to the inspection device 1B, and the inspection device 1B carries out the substrate 2 to the downstream process side. In addition to the above, the operator OP is informed that the substrate 2 inspected by the inspection device 1B is to be discarded. This notification is performed, for example, through the touch panel 51 or the like. When the inspection device 1B includes a discharge conveyor that discharges the discarded substrate, the inspection device 1B that receives the substrate discard command from the printing device control unit 50 carries out the substrate 2 that is the discard target to the discharge conveyor. May be.

In the clogging inspection step of step ST13, the printing device control unit 50 moves the camera unit 16 below the mask 15 by the camera unit moving mechanism 16K, and causes the upper imaging unit 16a of the camera unit 16 to open each opening of the mask 15. This is done by imaging 15H. Then, for example, the original opening area of each opening 15H of the mask 15 is compared with the opening area after printing calculated from the image obtained by imaging, and the opening area after printing calculated with respect to the original opening area. When the ratio of <1> is less than the predetermined treatment ratio, it is determined that the opening 15H is clogged. When such a determination is performed for each opening 15H in the entire area of the mask 15 and it is determined that at least some openings are clogged, it is determined that the mask 15 is clogged.

When the clogging inspection is executed in step ST13 and it is determined that the opening of the mask 15 is clogged, the printer controller 50 operates the camera unit moving mechanism 16K to move the mask cleaner 18 to the Y-axis. 11A to 11B, the paste Pst adhering to the lower surface of the mask 15 is wiped to clean the back surface of the mask 15 (mask cleaning step of step ST14).

After cleaning the mask 15 in step ST14, the clogging inspection is performed again (step ST15). As a result, if the clogging of the mask 15 is eliminated, the process returns to the main routine, and if the clogging of the mask 15 is not eliminated, the printing operation of the screen printing apparatus 1A is stopped, The touch panel 51 or the like is informed of the abnormal stop to urge the operator OP to take measures (step ST16), and returns to the main routine. Further, even when it is determined that the printing amount is not insufficient in the printing amount inspection step of the above-mentioned step ST12, the notification of the abnormal stop is given in step ST16, and the operator OP is urged to take measures. The operator OP who is urged to take countermeasures in step ST16 attempts to change the setting of printing conditions such as changing the pressure (printing pressure) with which the squeegee 43 contacts the mask 15, or the mask from the opening 15H of the mask 15. It is confirmed whether or not the paste Pst wraps around the back surface of the mask 15 to cause “bleeding” that stains the back surface of the mask 15.

On the other hand, when it is determined in step ST13 that the mask 15 is not clogged as a result of the clogging inspection, the printing device control unit 50 performs the immediately preceding scraping operation of the paste Pst by the squeegee 43. The time interval (pause duration) between the scraping operation of the paste Pst and the scraping operation of the paste Pst immediately before is calculated by referring to the movement history of the print head moving mechanism 17K (step ST17). .. Then, it is determined whether or not the calculated pause duration time exceeds a preset reference time (step ST18), and the printing condition is changed according to the determination result. Here, the reference time is determined on the basis of the time during which the filling property of the mask 15 into the opening 15H is lowered due to the squeegee 43 sliding (squeezing) on the mask 15 by leaving the paste Pst, for example, The time is set to 20 to 30 minutes.

Here, it is assumed that the printing condition is the sliding speed of the squeegee 43 on the mask 15, and in step ST18, when the rest duration time exceeds the preset reference time, the squeegee on the mask 15 is set. It is changed so as to increase the sliding speed of 43 (step ST19). The reason why the sliding speed of the squeegee 43 is increased is to prevent the fluidity from being lowered due to the increase in viscosity of the paste Pst due to being left and to facilitate the transfer onto the substrate 2. On the other hand, in step ST18, when the rest duration does not exceed the reference time, the sliding speed of the squeegee 43 on the mask 15 is changed to be lowered (step ST20). The reason why the sliding speed of the squeegee 43 is increased is to secure a sufficient time for the paste Pst to pass through the opening 15H of the mask 15. If the rest duration is exactly the same as the reference time, either increasing or decreasing the sliding speed of the squeegee 43 may be adopted, or the current sliding speed may be maintained. ..

When the subroutine ends and returns to the main routine, the printing device control unit 50 determines whether or not to end a series of operations based on whether or not the screen printing operation has been performed on all the substrates 2 on which the paste Pst is to be printed. It is determined (step ST9 of FIG. 8). When it is determined that the work should not be ended, the process returns to step ST1. Here, when it is time to return to step ST1 and the setting is made to change the sliding speed of the squeegee 43 on the mask 15 in step ST8, the changed sliding is performed in the printing process performed thereafter. Since the squeegee 43 is slid at the speed, the probability that the printed state of the paste Pst will be improved is high. On the other hand, when the printing apparatus control unit 50 determines that the work should be ended, the work is ended.

FIG. 12 shows a modified example of the subroutine of the screen printing work. This modification is different from the example of FIG. 9 in that, when it is determined that the print amount is not insufficient in the print amount inspection step of step ST12, the paste Pst wraps around from the opening 15H of the mask 15 to the back surface of the mask 15. Assuming that "bleeding" has occurred, the back surface of the mask 15 is cleaned by the mask cleaner 18 (step ST21). Then, when the cleaning of the mask 15 is completed, a bleeding inspection is executed (step ST22).

In the bleeding inspection in step ST22, the camera unit moving mechanism 16K moves the camera unit 16 below the mask 15, and the upper image pickup unit 16a of the camera unit 16 takes an image of a region in the vicinity of each opening 15H provided in the mask 15. To do. Then, when the paste Pst spreads in the vicinity of the opening 15H beyond the predetermined reference range, it is determined that the bleeding has not been eliminated, and the printing operation of the screen printing apparatus 1A is stopped, and then the touch panel. 51 or the like is informed of the abnormal stop, and the operator OP is prompted to take measures (step ST16), and the process returns to the main routine. On the other hand, in step ST22, when the spread of the paste Pst is within the range of the reference, the bleeding is resolved, and the process returns to the main routine.

In this modification, when the print amount insufficiency is not detected in the print amount inspection step of step ST12, and the bleeding occurs in the mask 15, the bleeding is automatically eliminated. Therefore, the burden on the operator OP is reduced, and it is not necessary to stop the printing operation of the screen printing apparatus 1A, so that the productivity is improved.

As described above, in the screen printing method according to the present embodiment, is there a shortage of the printing amount of the paste Pst on the substrate 2 which is the print target on which the paste Pst is printed in the printing process (step ST1 to step ST6)? As a result of performing the print amount inspection step (step ST12) for inspecting whether or not the print amount of the paste Pst is insufficient on the substrate 2, it is further detected that the opening 15H of the mask 15 is clogged. A clogging inspection process for inspecting whether or not it has occurred is executed (step ST13). Then, the mask 15 is cleaned only when it is detected in the clogging inspection step that the opening of the mask is clogged (step ST14). Therefore, even if the print amount of the paste Pst is insufficient, if the mask 15 is not clogged, the mask 15 is not cleaned, and wasteful mask cleaning is performed, thereby lowering productivity. It can be prevented.

Further, in the screen printing method according to the present embodiment, when it is detected that the opening 15H of the mask 15 is not clogged in the clogging inspection step, the pause duration of the printing step is set to a preset reference time. It is determined whether or not it has exceeded, and the printing condition (sliding speed of the squeegee 43 on the mask 15) is changed according to the determination result. When the print amount is insufficient, the cause may be clogging of the mask 15 or improper printing conditions. In this respect, according to the screen printing method of the present embodiment, when a shortage of the printing amount is detected, a countermeasure other than the mask cleaning is automatically executed, and the operator OP's hand is not required. Therefore, productivity can be improved.

Although the embodiments of the present invention have been described so far, the present invention is not limited to those described in the above embodiments. For example, in the above-described embodiment, the printing condition that is changed depending on whether the pause duration of the printing process exceeds the preset reference time is the sliding speed of the squeegee 43 on the mask 15. However, this is an example, and the printing speed is not limited to the sliding speed of the squeegee 43 and may be other printing conditions. For example, when the rest duration exceeds the reference time and a viscosity increase due to leaving the paste Pst is assumed, the sliding speed of the squeegee 43 does not change and the printing pressure is increased for the purpose of improving the scraping property of the paste Pst. You can also raise it. Further, when the pause duration time does not exceed the reference time, it can be assumed that the amount of the paste Pst has become insufficient, and it is possible to give an additional supplement instruction of the paste Pst.

Further, when the sliding speed of the squeegee 43 on the mask 15 is set as the printing condition to be changed, in the above-described embodiment, when the rest duration time exceeds the reference time, the squeegee 43 slides. If the moving speed is increased and the rest duration does not exceed the reference time, the sliding speed of the squeegee 43 is reduced, and either the slide speed of the squeegee 43 should be raised or lowered depending on the rest duration. However, if the pause duration exceeds the reference time, increase the sliding speed of the squeegee 43, and if the pause duration does not exceed the reference time, It is also possible to adopt a flexible setting, such as adopting only one of "decreasing the sliding speed of the squeegee 43" and leaving the sliding speed of the squeegee 43 unchanged in other cases.

Further, in the above-described embodiment, the print target as the target on which the paste Pst is printed is the printed circuit board for forming an electronic circuit, but this is an example, and the printed board is not necessarily the substrate 2. ..

It is possible to prevent an increase in tact due to unnecessary mask cleaning.

2 substrates (print target)
15 Mask 15H Open 43 Squeegee Pst paste

Claims (3)

A squeegee is slid on the mask brought into contact with the print target, and a printing step of printing the paste on the print target through the opening of the mask by scraping the paste supplied onto the mask with the squeegee,
A print amount inspection step of inspecting whether or not a shortage of the print amount of the paste has occurred in the print target on which the paste is printed in the printing step,
A clogging inspection step for inspecting whether or not clogging occurs in the opening of the mask when it is detected that the printing amount of the paste is insufficient in the printing object in the printing amount inspection step,
The clogging inspection process by the mask cleaning process and look at free to clean the mask if it is detected that the clogging occurs in the opening of the mask,
When it is detected that the opening of the mask is not clogged in the clogging inspection step, it is determined whether or not the pause duration of the printing step exceeds a preset reference time, and the determination is made. A screen printing method characterized by changing printing conditions according to a result . The printing condition is a sliding speed of the squeegee on the mask, and is changed so as to increase a sliding speed of the squeegee on the mask when the rest duration exceeds the reference time. The screen printing method according to claim 1 , wherein: The printing condition is a sliding speed of the squeegee on the mask, and is changed so as to reduce the sliding speed of the squeegee on the mask when the rest duration does not exceed the reference time. screen printing method according to claim 1 or 2, characterized in that.

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