Screen printing machine

Abstract

A screen printer prints a viscous fluid on a substrate using a mask on which a printing pattern comprising through-holes is formed. A screen printing machine includes: a substrate holding device that holds a substrate; a mask holding device that holds an end portion of the mask along an outer periphery of the mask at a position above the substrate held by the substrate holding device; an air nozzle capable of spraying air to a target point on the upper surface of the mask held at a position above the substrate; and a displacement amount measurement device that, when air is ejected from the air nozzle to the target point, measures the amount of displacement in the vertical direction of one or more measurement target points corresponding to the target point on the upper surface before and after the air is ejected.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a screen printing machine. Background Art

[0002] There is known a screen printing machine that fills a viscous fluid into through-holes of a mask while holding the mask above a substrate. In the screen printing machine, when filling the viscous fluid into the through-holes, if a gap is generated between the mask and the substrate, the viscous fluid may intrude into the gap. The screen printing machine of Patent Document 1 presses the shaft of an actuator onto the upper surface of the mask from above the mask. Thereby, the mask is displaced downward toward the substrate according to the size of the gap formed between the mask and the substrate. The screen printing machine measures the distance between the mask and the substrate based on the displacement amount of the shaft of the actuator (i.e., the mask).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Utility Model Laid-Open No. 04-100849 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] In the above-described screen printing machine, in order to measure the distance between the mask and the substrate, the shaft of the actuator is pressed onto the upper surface of the mask. Therefore, the shaft may damage the upper surface of the mask. In this specification, a technology is provided that can reduce damage to the upper surface of the mask when measuring the distance between the mask and the substrate as compared with the prior art.

[0008] Means for Solving the Problems

[0009] The screen printing machine disclosed in this specification prints a viscous fluid on a substrate using a mask having a printing pattern formed of through-holes. The screen printing machine includes: a substrate holding device that holds the substrate; a mask holding device that holds an end portion of the mask along an outer periphery of the mask at a position above the substrate held by the substrate holding device; an air nozzle that can eject air to a target point on the upper surface of the mask held at a position above the substrate; and a displacement amount measuring device that measures a displacement amount in the vertical direction of one or more measurement target points corresponding to the target point on the upper surface before and after ejecting the air from the air nozzle to the target point.

[0010] According to the above-mentioned screen printing machine, the mask is displaced by the air ejected from the air nozzle without directly contacting the upper surface of the mask. Thus, the displacement amount in the vertical direction of the measurement target point on the upper surface of the mask can be measured in a non-contact manner. When measuring the distance between the mask and the substrate, the above-mentioned screen printing machine can reduce the damage to the upper surface of the mask. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a side view of the screen printing machine of the first embodiment.

[0012] Figure 2 is Figure 1 an enlarged view of the range of the dashed line II in

[0013] Figure 3 is a top view of the mask disposed in the screen printing machine of the first embodiment.

[0014] Figure 4 is a structural diagram of the control device of the screen printing machine of the first embodiment.

[0015] Figure 5 is a flowchart of the substrate printing process executed by the control device of the first embodiment.

[0016] Figure 6 is a flowchart of the substrate printing process executed by the control device of the second embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The main features of the embodiments described below are listed. It should be noted that the technical elements described below are independent technical elements, and they exhibit technical utility through individual or various combinations, and are not limited to the combinations described in the claims at the time of application.

[0018] (Feature 1) In the above-mentioned screen printing machine, it is also possible that the one or more measurement target points include the target point.

[0019] When air is ejected from the nozzle to the target point, at the target point, the displacement in the vertical direction is likely to be larger than that of the points around the target point. According to such a structure, compared with the structure for measuring the displacement amount in the vertical direction of the points around the target point, the displacement in the vertical direction can be easily measured.

[0020] (Feature 2) The above-mentioned screen printing machine may further include: a substrate lifting device that lifts the substrate holding device when printing the viscous fluid on the substrate; and a lifting amount determination unit that determines the lifting amount of the substrate holding device. In this case, the lifting amount determination unit may determine the lifting amount based on the displacement amount of the one or more measurement target points measured by the displacement amount measuring device.

[0021] According to such a structure, the substrate can be brought closer to the mask based on the displacement amount of one or more measurement object points. Therefore, when printing a viscous fluid on the substrate, the distance between the substrate and the mask can be reduced.

[0022] (Feature 3) The above-described screen printing machine may further include an ejection amount determination unit that determines the ejection amount of the air ejected from the air nozzle. In this case, the target point may include a first target point and a second target point different from the first target point. It may be that the ejection amount determination unit determines the ejection amount of the air for the second target point as a second ejection amount different from the first ejection amount of the air for the first target point. The displacement amount measuring device may also measure the displacement amount in the vertical direction of a first measurement object point corresponding to the first target point and measure the displacement amount in the vertical direction of a second measurement object point corresponding to the second target point.

[0023] According to such a structure, the ejection amount of the air can be changed according to the position of the target point. Thereby, the ejection amount of the air suitable for the position of the target point can be determined.

[0024] (Feature 4) The above-described screen printing machine may further include an opening area determination unit that determines the opening area of the ejection port of the air nozzle. In this case, the target point may include a first target point and a second target point different from the first target point. The opening area determination unit may also determine the opening area of the ejection port for the second target point as a second opening area different from the first opening area of the ejection port for the first target point. The displacement amount measuring device may also measure the displacement amount in the vertical direction of a first measurement object point corresponding to the first target point and measure the displacement amount in the vertical direction of a second measurement object point corresponding to the second target point.

[0025] According to such a structure, the opening area can be changed according to the position of the target point. Thereby, the opening area suitable for the position of the target point can be determined.

[0026] (Feature 5) The above-described screen printing machine may further include an operation control unit that controls the operation of the substrate holding device, and the substrate holding device may have a clamp that holds the end of the substrate. In this case, it may be that the operation control unit, when the displacement amount of the measurement object point measured by the displacement amount measuring device exceeds a predetermined threshold amount, after releasing the end of the substrate by the clamp, causes the clamp to hold the end of the substrate again.

[0027] When the clamping member holds the end portion of the substrate, the substrate sometimes bends. In this case, the distance between the mask and the substrate tends to increase. As a result, the displacement amount in the vertical direction of the measurement target point increases. According to such a configuration, when the displacement amount exceeds a predetermined threshold value, the clamping member releases the end portion of the substrate and re - holds the end portion of the substrate. Thereby, the bending of the substrate can be eliminated.

[0028] (Feature 6) The above - mentioned screen printing machine may further include: a squeegee that fills the viscous fluid into the through - holes of the mask; and a squeegee operation determination unit that determines the force pressing the squeegee against the upper surface of the mask and the speed at which the squeegee moves along the upper surface of the mask. In this case, the squeegee operation determination unit may also determine at least one of the force and the speed based on the displacement amount of the measurement target point measured by the displacement amount measuring device.

[0029] According to such a configuration, the operation of the squeegee (i.e., at least one of the force and the speed) is determined based on the displacement amount. Thereby, the screen printing machine can perform printing suitable for the distance between the mask and the substrate.

[0030] (First Embodiment)

[0031] Refer to Figures 1 to 3 , the structure of the screen printing machine 10 (hereinafter referred to as the printing machine 10) of the first embodiment will be described. The printing machine 10 is a device that prints solder paste 38, which is a viscous fluid, on a circuit board 2 (hereinafter referred to as the substrate 2) as an object to be printed using a mask 20 and transports it to an electronic component mounting device as a subsequent process. Hereinafter, the - Y direction in the drawing is represented as the front side. In addition, the + Y direction is represented as the rear side, the + Z direction is represented as the upper side, and the - Z direction is represented as the lower side.

[0032] Figure 1 FIG. shows a side view of the printing machine 10. The printing machine 10 includes a squeegee unit 30, a unit driving device 12, a mask holding device 24, a substrate holding device 14, a gap measuring unit 40, a control device 50, a high - pressure tank 4, and an adjustment valve 6 in a box - shaped housing. In addition, in Figure 1 FIG., the housing of the printing machine 10 is depicted in a perspective view, but in reality, it is composed of six - sided plates that divide the interior of the printing machine 10.

[0033] The squeegee unit 30 includes a squeegee 36, an angle adjustment device 34, and a lifting device 32. The squeegee 36 is a flat plate-like member having a rectangular shape extending in the X-axis direction. The squeegee 36 of the present embodiment is a metal squeegee made of metal, but in a modified example, it may be a polyurethane squeegee, for example. The angle adjustment device 34 adjusts the posture of the squeegee 36 relative to the substrate 2 (the angle formed between the upper surface of the substrate 2 and the squeegee 36). The lifting device 32 moves the squeegee 36 in the vertical direction. In addition, the lifting device 32 raises and lowers the squeegee 36 relative to the substrate 2 in the vertical direction to adjust the pressure for pressing the squeegee 36 against the mask 20 (hereinafter referred to as the printing pressure).

[0034] The substrate holding device 14 includes a pair of clamping members 16F and 16S. The pair of clamping members 16F and 16S hold the substrate 2 from the front and rear. Thus, the substrate 2 is fixed to the substrate holding device 14. A substrate lifting device 15 and a substrate transfer device 16 are arranged below the substrate holding device 14. The substrate lifting device 15 has a servo motor (not shown). The substrate lifting device 15 raises and lowers the substrate holding device 14 by operating the servo motor. Similarly, the substrate transfer device 17 has a servo motor (not shown), and by operating the servo motor, the substrate 2 before printing is transferred to the substrate holding device 14, and the substrate 2 after printing is transferred from the substrate holding device 14 in the +X direction (i.e., Figure 1 the direction near the front of the paper surface of

[0035] The unit driving device 12 moves the squeegee unit 30 in the front-rear direction (i.e., Figure 1 the left-right direction of the paper surface of

[0036] Specifically, as Figure 3 shown, the mask holding device 24 includes a frame disposed along the outer periphery of the mask 20. The frame of the mask holding device 24 holds the end portion of the mask 20. Thus, when the solder paste 38 is filled into the through holes 22 of the mask 20 by the squeegee unit 30, the positional deviation of the mask 20 can be suppressed. A plurality of holding mechanisms 26 are provided in the mask holding device 24. The mask holding device 24 holding the end portion of the mask 20 is held at a position above the substrate 2 by the plurality of holding mechanisms 26.

[0037] A plurality of through holes 22 are formed in the mask 20. The plurality of through holes 22 are arranged according to the printing pattern 21. When the solder paste 38 is pressed against the upper surface of the mask 20 by the squeegee 36, the solder paste 38 adheres to the substrate 2 through the plurality of through holes 22 (i.e., the printing pattern 21). Thus, the solder paste 38 is printed on the upper surface of the substrate 2 according to the printing pattern 21.

[0038] The gap measurement unit 40 is a unit for measuring the distance (gap) between the mask 20 and the upper surface of the substrate 2 when printing the solder paste 38 on the substrate 2. The gap measurement unit 40 includes an air nozzle 44 (hereinafter referred to as the nozzle 44), a displacement sensor 46, a lifting device 42, and a driving device 48. The nozzle 44 is connected to the high-pressure tank 4 via an adjustment valve 6. Compressed air is stored in the high-pressure tank 4. When the adjustment valve 6 is opened, the air in the high-pressure tank 4 is ejected from the nozzle 44 toward the mask 20. In addition, according to the opening degree of the adjustment valve 6, the ejection amount of the air ejected from the nozzle 44 toward the mask 20 is changed.

[0039] The displacement sensor 46 is a so-called optical sensor. The displacement sensor 46 has a light projecting part and a light receiving part inside. The displacement sensor 46 irradiates the object to be measured with laser light from the light projecting part. The irradiated light is reflected by the object to be measured, and the reflected light enters the light receiving part. The displacement sensor 46 detects the displacement of the non-measured object based on the change in the position of the light incident on the light receiving part. In addition, in a modified example, the displacement sensor 46 may be an ultrasonic sensor, for example.

[0040] The lifting device 42 moves the nozzle 44 and the displacement sensor 46 in the vertical direction. The driving device 48 moves the nozzle 44 and the displacement sensor 46 in the X direction. In addition, the gap measurement unit 40 can be moved in the front-rear direction (Y direction) of the printing machine 10 by the unit driving device 12. That is, the gap measurement unit 40 can move the nozzle 44 and the displacement sensor 46 along the upper surface of the mask 20.

[0041] Refer to Figure 2 The nozzle 44 and the displacement sensor 46 of the gap measurement unit 40 will be described. The nozzle 44 has a cylindrical shape extending in the vertical direction. An opening 47 and an opening adjustment part 45 are provided at the lower end of the nozzle 44. The opening adjustment part 45 is a mechanism for changing the area of the opening 47 and has a wall that defines the opening 47 of the nozzle 44. When the wall of the opening adjustment part 45 moves toward the center of the nozzle 44, the area of the opening 47 of the nozzle 44 becomes smaller. When the wall of the opening adjustment part 45 moves in a direction away from the center of the nozzle 44, the area of the opening 47 becomes larger.

[0042] As described above, the mask 20 is held by the mask holding device 24 at a position above the substrate 2. In addition, the substrate 2 is disposed below the mask 20 in a state where the ends are held by a pair of clamping members 16F, 16S of the substrate holding device 14. Here, since the mask 20 is a thin film with a thickness of 1 mm or less, for example, it can be displaced locally in the vertical direction. And since the substrate 2 also has a relatively thin flat plate shape, when the ends of the substrate 2 are held by the clamping members 16F, 16S, for example, it may be deformed in such a way that the central part is bent upward. As a result, as Figure 2As shown, a gap with a length C1 that varies according to the position may be generated between the lower surface 20D of the mask 20 and the upper surface 2U of the substrate 2.

[0043] If a large gap is generated between the lower surface 20D of the mask 20 and the upper surface 2U of the substrate 2, when filling the through hole 22 with the solder paste 38, the solder paste 38 enters the gap. As a result, printing defects may occur where the solder paste 38 is printed at an undesired position on the substrate 2.

[0044] The gap measurement unit 40 measures the distance between the lower surface 20D of the mask 20 and the upper surface 2U of the substrate 2 before the printing machine 10 performs printing, that is, before the squeegee 36 moves backward. Specifically, the gap measurement unit 40 ejects air 60 through the nozzle 44 onto the target point PB on the upper surface 20U of the mask 20. When there is a gap between the lower surface 20D of the mask 20 and the upper surface 2U of the substrate 2, the mask 20 is displaced downward by the length C1 of the gap, and the lower surface 20D of the mask 20 abuts against the upper surface 2U of the substrate 2. That is, the displacement amount of the mask 20 becomes the length C1 of the gap. The displacement sensor 46 measures the displacement between the target point PB before ejecting the air 60 and the target point PA after ejecting the air 60. Thus, the gap measurement unit 40 can measure the length C1 of the gap. The gap measurement unit 40 sends the measured length C1 of the gap to the control device 50.

[0045] For example, as Figure 3 shown, the gap measurement unit 40 of the present embodiment measures the length of the gap at the target points P1 to P9. The target points P1, P3, P6, and P8 are arranged at the four corners of the mask 20. The target point P4 is arranged at the center of the mask 20. The target points P2, P5, P7, and P9 are arranged at the centers of the respective sides of the mask 20.

[0046] Refer to Figure 4 to describe the structure of the control device 50. The control device 50 is composed of a computer having a memory 51 and a CPU 54. The control device 50 is communicably connected to each device 6 to 45 of the printing machine 10.

[0047] The memory 51 is composed of a storage medium such as an HDD. The memory 51 stores a printing program 52. The printing program 52 is a program for printing the solder paste 38 on the substrate 2 using the mask 20. The printing program 52 includes a target point table T1, threshold displacement amounts Dth1, Dth2, and a printing setting 53.

[0048] In the target point table T1, the coordinates, ejection amounts, and opening areas of the respective target points P1 to P9 are stored in an associated manner. The target point table T1 is a table for determining the ejection amounts of the air 60 and the opening areas of the nozzles 44 at the respective target points P1 to P9. The target point table T1 is pre-stored in the printing program 52, but the operator can also change, add, or delete the coordinates of the target points based on the actual printing results. Further, the operator can also change the ejection amounts and the opening areas.

[0049] In the target point table T1 of the present embodiment, ejection amounts V1 are set at the target points P1 to P3, P6 to P8. On the other hand, ejection amounts V2 are set at the target points P4, P5, and P9. As Figure 3 shown, the target points P4, P5, and P9 are located at the center in the front-back direction of the substrate 2 (i.e., Figure 3 the left-right direction in the plane of the paper). As described above, the end portions in the front-back direction of the substrate 2 are held by a pair of clamping members 16F, 16S, so the central portion in the front-back direction is likely to displace upward. Therefore, at the target points P4, P5, and P9, the distance between the upper surface 2U of the substrate 2 and the lower surface 20D of the mask 20 (i.e., the length C1 of the gap) is likely to become smaller. On the other hand, at the target points P1 to P3, P6 to P8, the length C1 of the gap is likely to become larger than that at the target points P4, P5, and P9. Therefore, the ejection amount V1 is set to be larger than the ejection amount V2. Thereby, at the end portions in the front-back direction of the substrate 2 where the length C1 of the gap is large, the air 60 with the ejection amount V1 larger than the ejection amount V2 can displace the mask 20 sufficiently until the lower surface 20D of the mask 20 abuts against the upper surface 2U of the substrate 2. As a result, the displacement sensor 46 can accurately measure the length C1 of the gap. That is, the printing machine 10 can accurately measure the gap C1 by changing the ejection amounts V1, V2 according to the positions of the target points P1 to P9.

[0050] Similarly, in the target point table T1 of the present embodiment, opening areas A1 are set at the target points P1 to P3, P6 to P8. On the other hand, opening areas A2 are set at the target points P4, P5, and P9. The opening area A1 is set to be larger than the opening area A2. Thereby, at the end portions in the front-back direction of the substrate 2 where the length C1 of the gap is large, the air 60 ejected through the opening area A1 larger than the opening area A2 can displace the mask 20 sufficiently until the lower surface 20D of the mask 20 abuts against the upper surface 2U of the substrate 2. As a result, the distance between the upper surface 2U of the substrate 2 and the lower surface 20D of the mask 20 can be accurately measured. That is, the printing machine 10 can accurately measure the length C1 of the gap by further changing the opening areas A1, A2 according to the positions of the target points P1 to P9.

[0051] The threshold displacement amount Dth1 is a threshold for determining whether the control device 50 performs the reset of a pair of clamping members 16F and 16S in the subsequent substrate printing process. The threshold displacement amount Dth2 is a threshold for determining whether the control device 50 changes the printing setting 53 in the substrate printing process. Each of the thresholds Dth1 and DTh2 is pre-stored in the printing program 52, but can also be changed by the operator.

[0052] The printing setting 53 includes a printing pressure F1 and a printing speed S1. They are values pre-stored in the printing program 52. The control device 50 can adjust the printing pressure through the lifting device 32 of the squeegee unit 30. The printing speed is the speed at which the squeegee unit 30 advances backward while filling the through holes 22 of the mask 20 with the solder paste 38. The control device 50 can adjust the printing speed through the unit drive device 12.

[0053] The CPU 54 executes various processes according to the printing program 52. As a result, the CPU 54 functions as a rise amount determination unit 55, an ejection amount determination unit 56, an opening area determination unit 57, an operation control unit 58, and a squeegee operation determination unit 59.

[0054] Refer to Figure 5 , the substrate printing process executed by the CPU 54 of the control device 50 of the printing machine 10 will be described. The substrate printing process starts according to the printing start instruction of the operator after the mask 20 is held by the mask holding device 24 and the substrate 2 is held by the substrate holding device 14.

[0055] In S10, the CPU 54 moves the nozzle 44 and the displacement sensor 46 in the order of the target points P1 to P9 based on the target point table T1. When moving the nozzle 44 and the displacement sensor 46 to each of the target points P1 to P9, the CPU 54 causes the nozzle 44 to eject air 60 to each of the target points P1 to P9. At this time, as described above, the CPU 54 changes to the ejection amount V1 or V2 and the opening area A1 or A2 based on the target point table T1 according to the target points P1 to P9.

[0056] In S12, the CPU 54 obtains the displacement amounts of each of the target points P1 to P9 before and after the ejection of the air 60 from the displacement sensor 46.

[0057] In S20, the CPU 54 compares the displacement amounts obtained from the displacement sensor 46 with the threshold displacement amount Dth1. When none of the displacement amounts exceed the threshold displacement amount Dth1 (S20: No), the CPU 54 proceeds to S22. When any of the displacement amounts exceed the threshold displacement amount Dth1 (S20: Yes), the CPU 54 proceeds to S24.

[0058] In S24, the CPU 54 resets a pair of clamping members 16F and 16S. Specifically, the CPU 54 causes the pair of clamping members 16F and 16S to release the front and rear ends of the substrate 2. After that, the CPU 54 causes the pair of clamping members 16F and 16S to grip the front and rear ends of the substrate 2 again. Thereby, the deformation of the substrate 2 caused by the gripping of the pair of clamping members 16F and 16S can be eliminated. As a result, the length C1 of the above-mentioned gap can be reduced.

[0059] In S22, the CPU 54 adjusts the height of the substrate holding device 14 based on the displacement amounts of the respective target points P1 to P9 acquired from the displacement sensor 46 in S12. For example, the CPU 54 causes the substrate holding device 14 to rise by the maximum displacement amount among the displacement amounts acquired from the displacement sensor 46 in S12 through the substrate lifting device 15. Thereby, when the solder paste 38 is printed on the substrate 2, the lower surface 20D of the mask 20 can be brought into contact with the upper surface 2U of the substrate 2. As a result, the occurrence of the above-mentioned printing defect can be suppressed. In addition, in a modified example, the CPU 54 may also cause the substrate holding device 14 to rise by the average value of the displacement amounts of the respective target points P1 to P9 acquired from the displacement sensor 46 in S12.

[0060] In S30, the CPU 54 compares the displacement amounts of the respective target points P1 to P9 acquired from the displacement sensor 46 with the threshold displacement amount Dth2. When none of the displacement amounts exceeds the threshold displacement amount Dth2 (S30: No), the CPU 54 skips S32 and proceeds to S40. When any of the displacement amounts exceeds the threshold displacement amount Dth2 (S30: Yes), the CPU 54 proceeds to S32.

[0061] In S32, the CPU 54 changes the printing setting 53. Specifically, the CPU 54 makes the printing pressure when passing through the target point indicating the displacement amount exceeding the threshold displacement amount Dth2 larger than the initial printing pressure F1, and makes the printing speed smaller than the initial printing speed S1. Thereby, at the target point indicating the displacement amount exceeding the threshold displacement amount Dth2, the squeegee 36 can press the mask 20 more strongly against the substrate 2. As a result, the occurrence of printing defects can be suppressed. In addition, in a modified example, the printing setting 53 may include at least one of the printing pressure F1 and the printing speed S1. In this case, in S32, the CPU 54 may change at least one of the printing pressure F1 and the printing speed S1.

[0062] In S40, the CPU 54 moves the squeegee unit 30 backward based on the printing setting 53 to perform printing. Thereby, the solder paste 38 is filled into the through holes 22 of the mask 20 and printed on the substrate 2.

[0063] The printing machine 10 according to the present embodiment can measure the displacement amounts in the vertical direction of the target points P1 to P9 without directly contacting the upper surface 20U of the mask 20 by the air 60 ejected from the nozzle 44. Therefore, when measuring the distance between the mask 20 and the substrate 2, the printing machine 10 can reduce the damage to the upper surface 20U of the mask 20.

[0064] (Second Embodiment)

[0065] Refer to Figure 4 and Figure 6 , the screen printing machine 10 of the second embodiment will be described. The screen printing machine 10 of the second embodiment has the same structure as the screen printing machine 10 of the above-described first embodiment, but the control device 50 of the screen printing machine 10 of the second embodiment performs a substrate printing process different from that of the control device 50 of the first embodiment.

[0066] As Figure 4 shown, the printing program 52 of the second embodiment includes a threshold displacement amount Dth3 instead of the two threshold displacement amounts Dth1 and Dth2 of the first embodiment. And, a coping process is registered in the printing program 52 of the second embodiment. The threshold displacement amount Dth3 is a threshold for determining whether the control device 50 performs a coping process in the Figure 6 shown substrate printing process. The coping process includes a printing setting change process, a clamp reset process, and a stop process. The printing setting change process is a process of changing the above-described printing setting 53. The clamp reset process is a process of performing the reset of the pair of clamps 16F and 16S. The printing stop process is a process of stopping the substrate printing process. Before the operator executes the substrate printing process, one of the three processes is selected. The selected process is registered in the printing program 52 as a coping process.

[0067] Refer to Figure 6 , the substrate printing process executed by the CPU 54 of the screen printing machine 10 of the second embodiment will be described. In S110 and S112, the same processes as S10 and S12 of Figure 5 are executed. In S120, the CPU 54 compares each displacement amount obtained from the displacement sensor 46 with the threshold displacement amount Dth3. When none of the displacement amounts exceed the threshold displacement amount Dth3 (S120: No), the CPU 54 proceeds to S140 and executes the printing process. When one of the displacement amounts exceeds the threshold displacement amount Dth3 (S120: Yes), the CPU 54 proceeds to S130.

[0068] In S130, the CPU 54 determines whether the response process registered in the printing program 52 is a printing stop process. When the response process is a printing stop process (S130: Yes), the CPU 54 stops the substrate printing process. Thereby, the operator can confirm the portion that has displaced beyond the threshold displacement amount Dth3, and correct the substrate or the mask at this portion.

[0069] When the response process registered in the printing program 52 by the CPU 54 is a printing change process (S130: No), in S132, the printing settings 53 are changed, and the printing process is executed (S140). In S132, the same process as that of Figure 5 S32 is executed.

[0070] When the response process registered in the printing program 52 by the CPU 54 is a clamp reset process (S130: No), in S134, a pair of clamps 16F, 16S are reset, and the process returns to S120.

[0071] Describe the points to note regarding the printing machine 10 described in the embodiment. For example, the displacement sensor 46 may also measure the displacements of four points on the same circumference centered on the target point P when looking down at the substrate 2, instead of measuring the displacement of the target point (e.g., P1). By measuring the displacements of the four points corresponding to the target point P, the length C1 of the gap can be accurately measured around the target point P. In addition, around the target point P, it is possible to measure which side the substrate 2 or the mask 20 is tilted towards. In this modification example, the four points are an example of the "multiple measurement object points".

[0072] For example, the nozzle 44 of the printing machine 10 may also eject air 60 only towards one target point P1. In this case, the ejection amounts V1, V2 may not be stored in the target point table T1. In this modification example, the "ejection amount determination unit" can be omitted. In addition, in other modification examples, the opening areas A1, A2 may not be stored in the target point table T1 either. In this modification example, the "opening area determination unit" can be omitted.

[0073] The substrate holding device 14 may not include a pair of clamps 16F, 16S. In this case, the substrate 2 may be disposed, for example, on the upper surface of the substrate holding device 14. In this case, the CPU 54 may not execute the processes of S20 and S22 either. In this modification example, the "operation control unit" can be omitted.

[0074] The CPU 54 may not execute the processes of S30 and S32 either. In this modification example, the "doctor blade operation determination unit" can be omitted.

[0075] In the target point table T1, instead of the ejection amount or the opening area, the ejection pressure may be stored in association with the coordinates of each of the target points P1 to P9. In this case, for example, the ejection pressures associated with the target points P1 to P3, P6 to P8 may also be set to be greater than the ejection pressures associated with the target points P4, P5, and P9. In a further modification, in the target point table T1, in addition to the ejection amount and the opening area, the ejection pressure may be stored in association with the coordinates of each of the target points P1 to P9.

[0076] In the above-described target point table T1, the ejection amount and the opening area are changed according to the distances between the target points P1 to P9 and the pair of clamping members 16F, 16S. Instead, the ejection amount and the opening area may also be changed, for example, according to the distances between the target points P1 to P9 and the mask holding device 24. In this case, for example, large ejection amounts V1 and opening areas A1 may be set for the target points P1 to P3, P5 to P9 among the target points P1 to P9 that are close to the mask holding device 24, and small ejection amounts V2 and opening areas A2 may be set for the target point P4 that is far from the mask holding device 24.

[0077] The technical elements described in this specification or the drawings exhibit technical utility through individual or various combinations, and are not limited to the combinations recited in the claims at the time of filing. In addition, the technologies illustrated in this specification or the drawings achieve multiple purposes simultaneously, and achieving one of these purposes itself has technical utility.

[0078] For example, in this specification, a technical idea of changing "the screen printing machine according to claim 1" to "the screen printing machine according to claim 1 or 2" in claim 3 is also disclosed. Similarly, a technical idea of changing "the screen printing machine according to claim 1" to "the screen printing machine according to any one of claims 1 to 3" in claim 4, a technical idea of changing "the screen printing machine according to claim 1" to "the screen printing machine according to any one of claims 1 to 4" in claim 5, a technical idea of changing "the screen printing machine according to claim 1" to "the screen printing machine according to any one of claims 1 to 5" in claim 6, and a technical idea of changing "the screen printing machine according to claim 1" to "the screen printing machine according to any one of claims 1 to 6" in claim 7 are also disclosed.

[0079] Description of Reference Numerals

[0080] 2: Circuit board

[0081] 2U, 20U: Upper surface

[0082] 4: High-pressure tank

[0083] 6: Adjusting valve

[0084] 10: Screen printing machine

[0085] 12: Unit drive device

[0086] 14: Substrate holding device

[0087] 15: Substrate lifting device

[0088] 16: Substrate transfer device

[0089] 16F, 16S: Clamping parts

[0090] 17: Substrate transfer device

[0091] 20: Mask

[0092] 20D: Lower surface

[0093] 21: Printed pattern

[0094] 22: Through hole

[0095] 24: Mask holding device

[0096] 26: Holding mechanism

[0097] 30: Squeegee unit

[0098] 32: Lifting device

[0099] 34: Angle adjustment device

[0100] 36: Squeegee

[0101] 38: Solder paste

[0102] 40: Gap measurement unit

[0103] 42: Lifting device

[0104] 44: Air nozzle

[0105] 45: Opening adjustment part

[0106] 46: Displacement sensor

[0107] 47: Opening

[0108] 48: Drive device

[0109] 50: Control device

[0110] 51: Memory

[0111] 52: Printing program

[0112] 53: Printing setting

[0113] 54: CPU

[0114] 55: Rise amount determination unit

[0115] 56: Spray amount determination unit

[0116] 57: Opening area determination unit

[0117] 58: Action control unit

[0118] 59: Blade action determination unit

[0119] 60: Air

[0120] A1, A2: Opening area

[0121] C1: Gap

[0122] Dth1, Dth2, Dth3: Threshold displacement amount

[0123] F1: Printing pressure

[0124] P1~P9, PA, PB: Target points

[0125] T1: Target point table

[0126] V1, V2: Spray amounts

Claims

1. A screen printing machine that prints a viscous fluid on a substrate using a mask formed with a printing pattern constituted by through holes. Among them, The screen printing machine includes: A substrate holding device that holds the substrate; A mask holding device that holds an end portion of the mask along an outer periphery of the mask at a position above the substrate held by the substrate holding device; An air nozzle capable of ejecting air to a target point on an upper surface of the mask held at a position above the substrate; And A displacement amount measuring device that measures an up-and-down displacement amount of one or more measurement object points corresponding to the target point on the upper surface before and after ejecting the air when ejecting the air from the air nozzle to the target point.

2. The screen printing machine according to claim 1, Among them, The one or more measurement object points include the target point.

3. The screen printing machine according to claim 1, Among them, The screen printing machine further includes: A substrate lifting device that lifts the substrate holding device when printing the viscous fluid on the substrate; and A lift amount determining unit that determines a lift amount of the substrate holding device, The lift amount determining unit determines the lift amount based on the displacement amount of the one or more measurement object points measured by the displacement amount measuring device.

4. The screen printing machine according to claim 1, Among them, The screen printing machine further includes an ejection amount determining unit that determines an ejection amount of the air ejected by the air nozzle, The target point includes a first target point and a second target point different from the first target point, The ejection amount determining unit determines the ejection amount of the air for the second target point as a second ejection amount different from a first ejection amount of the air for the first target point, The displacement amount measuring device measures an up-and-down displacement amount of a first measurement object point corresponding to the first target point and measures an up-and-down displacement amount of a second measurement object point corresponding to the second target point.

5. The screen printing machine according to claim 1, Among them, The screen printing machine further includes an opening area determining unit that determines an opening area of an ejection port of the air nozzle, The target point includes a first target point and a second target point different from the first target point, The opening area determining unit determines the opening area of the ejection port for the second target point as a second opening area different from a first opening area of the ejection port for the first target point, The displacement amount measuring device measures an up-and-down displacement amount of a first measurement object point corresponding to the first target point and measures an up-and-down displacement amount of a second measurement object point corresponding to the second target point.

6. The screen printing machine according to claim 1, Among them, The screen printing machine further includes an operation control unit that controls an operation of the substrate holding device, The substrate holding device has a clamping member that holds an end portion of the substrate. When the displacement amount of the measurement target point measured by the displacement amount measurement device exceeds a predetermined threshold amount, the motion control unit releases the end portion of the substrate by the clamping member and then causes the clamping member to grip the end portion of the substrate again.

7. The screen printing machine according to claim 1, wherein, the screen printing machine further includes: a squeegee that fills the through holes of the mask with the viscous fluid; and a squeegee motion determination unit that determines the force for pressing the squeegee against the upper surface of the mask and the speed for moving the squeegee along the upper surface of the mask, the squeegee motion determination unit determines at least one of the force and the speed based on the displacement amount of the measurement target point measured by the displacement amount measurement device.

Images