JP7702909B2 - Screen Printing Equipment - Google Patents

Description

This disclosure relates to a screen printing device.

The screen printing device is equipped with a mask, a squeegee, and a moving device that moves the squeegee back and forth. After supplying solder paste to the top surface of the mask, the squeegee is moved back and forth, so that the solder paste on the top surface of the mask is scraped off by the squeegee and printed on the substrate placed on the bottom surface of the mask. During the printing operation, the solder paste on the mask is pressed by the squeegee and rolled, forming it into a roll (solder roll).

The following Patent Document 1 discloses that a solder sensor is used to detect the solder roll that has been formed into a roll shape by rolling during printing. The solder sensor is an optical sensor that scans the solder roll on a screen (mask) after printing is completed and measures the roll width of the solder roll by detecting the positions of both ends of the solder roll.

Patent No. 5938102

When detecting the roll width of the solder roll, if the solder sensor passes over an area where the solder has not been scraped, it may erroneously detect the positions of both ends of the solder roll, resulting in an abnormal value. In addition to passing over an area where the solder has not been scraped, the same problem can occur if the shape of the solder roll becomes distorted when the squeegee is raised after printing is completed, or if some of the solder paste falls near the solder roll.

The objective of the present invention is to improve the detection accuracy of the roll width of a solder roll.

The screen printing device includes a mask, a squeegee, a moving device that moves the squeegee back and forth over the mask from a printing start position to a printing end position, a sensor that detects the solder paste on the mask, and a control unit.

The control unit uses the moving device to move the squeegee back and forth over the mask, scraping the solder paste on the upper surface of the mask with the squeegee and printing it on the substrate placed under the mask.

After printing is completed, the control unit uses the sensor to scan the solder roll located in front of the printing end position in the squeegee movement direction to detect both ends of the solder roll, and calculates the roll width of the solder roll in the front-to-rear direction based on the detection position of the solder roll by the sensor and the printing end position.

The solder roll is formed into a roll shape by rolling the solder paste on the mask as it is pressed by the squeegee during the printing operation.

In this configuration, the solder roll width is calculated by taking into account the print end position in addition to the sensor detection results, so the solder roll width can be calculated more accurately and robustly than when the solder roll width is calculated by relying solely on the sensor detection results.

The control unit may calculate the roll width using a first detection method in which the detection position of the rear side of the solder roll by the sensor is the starting point of the solder roll when the detection position of the rear side of the solder roll by the sensor is forward of the printing end position of the squeegee.
When the detection position on the rear side of the solder roll detected by the sensor is behind the printing end position of the squeegee, the control unit may calculate the roll width using a second detection method in which the printing end position of the squeegee is used as the starting point of the solder roll.

This configuration can prevent the roll width of the solder roll from being calculated as a value larger than the actual value due to the influence of dropped solder or unscraped areas. This prevents abnormal values for the roll width from being detected, thereby preventing error stoppages in the production line and improving takt time.

The screen printing device may include a selection input unit. The selection input unit allows the operator to select whether to use a first detection method in which the detection position on the rear side of the solder roll detected by the sensor is the start point of the solder roll, or a second detection method in which the printing end position of the squeegee is the start point of the solder roll, and the control unit may determine the detection method according to the operator's selection.

The method for detecting the starting point of the solder roll can be fixed during production at the operator's discretion, reducing variations in roll width caused by differences in detection methods.

The control unit may calculate the roll width using both detection methods, a first detection method in which the detection position on the rear side of the solder roll by the sensor is the starting point of the solder roll, and a second detection method in which the printing end position of the squeegee is the starting point of the solder roll, and the control unit may determine the detection method for the starting point of the solder roll based on the roll widths calculated using the two detection methods until the number of boards produced reaches a predetermined number of boards produced.

The system can automatically determine the detection method that best suits the characteristics of the board, mask, and solder before the production volume of boards reaches a specified production volume. This helps prevent printing machine stoppages and production delays caused by errors.

The control unit may determine, based on past production performance, which detection method to use to detect the start point of the solder roll: a first detection method in which the position detected by the sensor on the rear side of the solder roll is the start point of the solder roll, or a second detection method in which the printing end position of the squeegee is the start point of the solder roll.

In this configuration, the reliability of the calculation results can be improved by adopting a start point detection method based on past performance. For example, when producing a board of the same type as a type that has been produced in the past, the start point can be detected using the same detection method as in the past, thereby suppressing fluctuations in roll width due to differences in detection methods.

If there is a production record of a board with similar production conditions to the board to be produced, the control unit may detect the starting point of the solder roll for the board to be produced using the detection method used in the production of the board with similar production conditions.

In this configuration, the detection method to be used for production can be automatically determined by selecting the detection method for boards with similar production conditions.

The control unit may display on the display unit the calculation result of the first roll width calculated using a first detection method in which the detection position on the rear side of the solder roll by the sensor is the start point of the solder roll, the calculation result of the second roll width calculated using a second detection method in which the printing end position of the squeegee is the start point of the solder roll, and a selection menu for the two detection methods.

By allowing the operator to decide the detection method for the starting point for themselves, they can be aware of which detection method is being used. In addition, the operator can select the most reliable detection method at any time based on their own judgment.

The control unit may store in the memory unit a unique ID of the board, a detection method for the starting point of the solder roll used in the production of the board, and a calculated result of the roll width of the solder roll in the front-to-rear direction, in association with each other.

The process by which the roll width was determined to be appropriate can be confirmed from the data stored and linked to the board's unique ID.

The present invention can improve the detection accuracy of the roll width of a solder roll.

FIG. 1 is a perspective view of a screen printing apparatus according to a first embodiment; FIG. 1 is a plan view of a screen printing device (with the housing removed); A cross-sectional view of line A-A in FIG. A cross-sectional view of line A-A in FIG. BB line cross-sectional view of FIG. A partial enlarged view of FIG. FIG. 1 is a diagram showing an electrical configuration of a screen printing device. Illustration of roll width measurement operation Illustration of roll width measurement operation Solder roll and detection results (1) Solder roll and detection results (2) Solder roll and detection results (3) Solder roll and detection results (4) Flowchart of solder roll calculation process Machine settings display screen Flowchart of solder roll calculation process in embodiment 2 Flowchart of solder roll calculation process in embodiment 3 Flowchart of solder roll calculation process in embodiment 4 Flowchart of solder roll calculation process in embodiment 5 Flowchart of solder roll calculation process in embodiment 6 Roll width calculation result (graph) display screen FIG. 1 shows information stored in a storage unit.

<Embodiment 1>
A screen printing apparatus (hereinafter also referred to as a "printing apparatus") 1 will be described with reference to Figures 1 to 12. The direction in which a squeegee 25 moves during printing is defined as the front-rear direction, the longitudinal direction of the squeegee 25 as the left-right direction, and the vertical direction as the up-down direction.

1. Overall Configuration The screen printing apparatus 1 is an apparatus that prints solder paste 70 on the surface of a plate-shaped substrate PX. As shown in Fig. 1, the printing apparatus 1 has a box-shaped housing 10. An opening through which the substrate PX is carried in is formed in the right wall of the housing 10, and an opening through which the substrate PX is carried out is formed in the left wall. The substrate PX is carried into the housing 10 from the opening in the right wall, and after the solder paste 70 is printed, it is carried out to the left side.

Figure 2 is a plan view of the screen printing device 1, and Figure 3A is a cross-sectional view of the screen printing device 1. The printing device 1 includes a pair of front and rear conveyors 11 for transporting the substrate PX, a mask 12, a pair of left and right mask holders 13, a substrate support device 16, a moving device 21, a front and rear moving device 22, and a squeegee head 23.

The mask 12 comprises a frame-shaped mask frame 12A and a sheet-shaped stencil 12B that is attached to the inside of the mask frame 12A. The stencil 12B is made of iron, aluminum, stainless steel, etc., and has printing openings (not shown) formed therein that correspond to the pattern of the solder paste 70 to be printed on the substrate PX.

The conveyor 11 is equipped with a conveyor belt that moves in a circulating manner in the left-right direction. The conveyor 11 is driven by a conveyor drive motor (not shown) and transports the substrate PX to be printed into and out of the printing device 1.

As shown in FIG. 3A, the substrate support device 16 has a backup plate 16A that can be raised and lowered below the mask 12. The substrate PX that is brought into the printing device 1 is placed on the upper surface of the backup plate 16A. The substrate support device 16 then moves to a specified printing position and raises the backup plate 16A to bring the substrate PX into close contact with the lower surface of the mask 12.

As shown in FIG. 3A, the mask holder 13 is L-shaped when viewed from the left and right direction. The mask holder 13 clamps the mask frame 12A from the front and back directions and fixes the mask 12 to the printing device 1.

As shown in Figures 2 and 4A, the moving device 21 has a rectangular parallelepiped shape that is long in the left-right direction, and supports the squeegee head 23 so that it can be raised and lowered. The forward/rearward moving device 22 has a ball screw 27 and a first motor 28. The ball screw 27 is a ball screw mechanism that moves the moving device 21 and the squeegee head 23 in the forward/rearward direction.

When the first motor 28 is driven, the ball screw 27 provides forward and backward propulsive force, causing the moving device 21 and the squeegee head 23 to move back and forth in the forward and backward directions.

The moving device 21 has a built-in second motor 30. By driving the second motor 30, the squeegee head 23 can be moved vertically relative to the moving device 21.

As shown in FIG. 4A, the squeegee head 23 rotatably supports the squeegee 25 via an arm portion 29. The squeegee head 23 incorporates a third motor 31, and the rotation of the motor can rotate the squeegee 25 around a rotation shaft 29A. As shown in FIG. 3A, the squeegee 25 has a shape that is long in the left-right direction. When the squeegee head 23 is lowered to the position shown in FIG. 3A, the tip of the squeegee 25 comes into contact with the surface of the stencil 12B, and the printing operation can be performed.

In addition, the squeegee head 23 also includes a supply section that supplies solder paste 70 to the upper surface of the stencil 12B.

2. Electrical Configuration of Printing Device 1 As shown in Fig. 5, the printing device 1 includes a display unit 14, a control unit 50, and an input unit 51. The control unit 50 includes a CPU 52, a RAM 53, and a storage unit 54. The display unit 14, the input unit 51, the moving device 21, the sensor 26, etc. are connected to the control unit 50.

The memory unit 54 stores various programs and data executed by the CPU 52. The display unit 14 is a display device such as a liquid crystal display. The input unit 51 is an input device such as a touch panel, a mouse, or a keyboard.

The control unit 50 controls the first motor 28 and the second motor 30 to move the squeegee 25 in the front-rear and up-down directions. It also controls the third motor 31 to rotate the squeegee 25 around the pivot shaft 29A.

The memory unit 54 also has information on the dimensions of the squeegee head 23, the squeegee 25, and the arm unit 29. Based on this information and the axis value information of each motor, the control unit 50 calculates the position and angle of the squeegee 25 on the mask 12.

3. Printing Process and Forming of Solder Roll 71 The printing process and forming of the solder roll 71 will be described with reference to FIG.
Before printing begins, the substrate PX is placed on the lower surface of the stencil 12B, and solder paste 70 is supplied to the upper surface of the stencil 12B by a supply unit mounted on the squeegee head 23.

As shown in FIG. 4A, when the squeegee 25 is moved forward (to the left in FIG. 4) from the printing start position S0, the solder paste 70 is pushed forward by the squeegee 25.

The solder paste 70 is pushed by the squeegee 25 and moves over the stencil 12B while rolling. The solder paste 70 fills the printing openings in the stencil 12B and is printed onto the substrate PX.

During printing, the squeegee 25 rolls a roll-shaped solder roll 71 in front of it. When the tip 25A of the squeegee 25 reaches the printing end position P0 (see Figure 4B), the printing process ends.

Figure 4B shows the positional relationship between the solder roll 71 and the squeegee 25 at the end of printing. In the squeegee movement direction, the solder roll 71 is located at or ahead of the printing end position P0 of the squeegee 25.

6, the sensor 26 is attached to the squeegee head 23. In this embodiment, the sensor 26 is attached to a position away from the center of the squeegee head 23, specifically, to a position toward the front of the right wall.

By driving the first motor 28 and the third motor 31, the sensor 26 can move in the front-back and up-down directions together with the squeegee head 23.

Sensor 26 is an optical sensor that has a light-emitting element that emits laser light and a light-receiving element that receives the laser light.

The sensor 26 is located above the stencil 12B, irradiates the stencil 12B with laser light from above, and receives the reflected light. In this embodiment, if the amount of light received is less than a threshold (if solder is present), the sensor 26 outputs an ON signal, and if the amount of light received is equal to or greater than the threshold (if solder is not present), the sensor 26 outputs an OFF signal.

As shown in FIG. 7, after the printing process is completed, the squeegee head 23 is raised and then retracted, and the sensor 26 is moved above the detection start position M1.

Then, while irradiating the upper surface of the stencil 12B with laser light, the squeegee head 23 is moved forward, and the sensor 26 is moved from the detection start position M1 to the detection end position M2.

This allows the solder roll 71 to be scanned with laser light and detected. The detection range M0 of the sensor 26 includes the printing end position P0 of the squeegee 25.

Figure 8 shows the output signal of the sensor 26 when the solder roll 71 is scanned. Detection position P1 is the position where the sensor output switches from OFF to ON, and detection position P2 is the position where the sensor output switches from ON to OFF. Note that when the sensor output at detection start position M1 is ON, detection start position M1 is set to detection position P1.

Detection position P1 is the detection position on the rear side of the solder roll 71, and is the starting point for calculating the roll width W. Detection position P2 is the detection position on the front side of the solder roll 71, and is the end point for calculating the roll width W. Then, by determining the distance H1 between the two points P1 and P2, the roll width W in the front-to-rear direction of the solder roll 71 can be calculated.

W=H1 (1)

The remaining amount of solder paste 70 can be estimated from the calculation result of the roll width W. After the printing process is completed, the roll width W is calculated, and if the remaining amount becomes small, solder paste 70 is replenished onto the mask 12, thereby preventing printing defects caused by a lack of solder. As described above, the method of detecting the roll width W in which the detection position P1 is set as the starting point of the solder roll 71 is defined as the first detection method.

<False Detection of Sensor 26>
9, when there is an unscraped portion 72 of the solder paste 70, the distance H1 between the two points calculated by the sensor 26 is greater than the actual roll width W. This is because the sensor output is ON not only for the solder roll 71 but also for the unscraped portion 72.

False detection by the sensor 26 may also occur if there is fallen solder 74 or if a corner 75 is formed on the solder roll 71 (see Figures 10 and 11).

As shown in FIG. 4B, the solder roll 71 is formed in front of the squeegee 25 in the squeegee movement direction. If there is no unscraped portion 72 or fallen solder 74, the detection position P1 of the solder roll 71 by the sensor 26 is located forward of the printing end position P0 of the squeegee 25.

On the other hand, if the detection position P1 of the solder roll 71 by the sensor 26 is behind the printing end position P0 of the squeegee 25, it is highly likely that the cause is an unscraped portion 72 or fallen solder 74.

Therefore, when the detection position P1 is behind the printing end position P0, the starting point of the solder roll 71 is set to the printing end position P0, not the detection position P1, as shown in Figures 9 to 11. The distance H2 between the two points P0 and P2 is set to the roll width W of the solder roll 71.

W=H2 (2)

When the detection position P1 is behind the printing end position P0, the start point of the solder roll 71 is set to the printing end position P0, so that the influence of the unscrewed portion 72, etc. can be eliminated and the roll width W can be accurately calculated. In this way, the detection method of the roll width W in which the printing end position P0 is set to the starting point of the solder roll 71 is referred to as the second detection method.

Figure 12 is a flowchart of the solder roll calculation process. After the printing process is completed, the control unit 50 scans the solder roll 71 with the sensor 26 and acquires data on the detection result of the sensor 26 (S10). At this time, data on the printing end position P0 of the squeegee 25 is also acquired.

Then, the control unit 50 determines whether solder is present in the detection range M0 (S20). The presence or absence of solder can be determined from the output signal of the sensor 26.

If solder is not present (S20: NO), the calculation process ends with a measurement error (S25). If solder is present (S20: YES), the control unit 50 determines whether the output signal of the sensor 26 at the detection end position M2 is OFF (S30).

If the output signal of the sensor 26 is ON (S30: NO), it is determined that the front end of the solder roll 71 is ahead of the detection end position M2, and the calculation process ends with a measurement error (S35).

If the output signal of the sensor 26 is OFF (S30: YES), the control unit 50 determines the end point of the solder roll 71 to be the detection position P2 in front of the sensor 26 (S40).

Next, the control unit 50 determines whether the detection position P1 of the sensor 26 is ahead of the printing end position P0 (S50).

If the detection position P1 of the sensor 26 is ahead of the printing end position P0 (S50: YES), the control unit 50 determines the start point of the solder roll 71 to be the detection position P1 of the sensor 26 (S60).

Then, the control unit 50 calculates the distance H1 between the end point (detection position P2) determined in S40 and the start point (detection position P1) determined in S60, and sets the calculated distance H1 between the two points as the roll width W (S70).

On the other hand, if the detection position P1 of the sensor 26 is behind the printing end position P0 (S50: NO), the control unit 50 determines that the start point of the solder roll 71 is the printing end position P0. (S55).

Then, the control unit 50 calculates the distance H2 between the end point (detection position P2) determined in S40 and the start point (print end position P0) determined in S55, and sets the calculated distance H2 between the two points as the roll width W (S70).

After calculating the roll width W, the control unit 50 determines whether the value of the roll width W is appropriate (S80). Specifically, it determines whether the roll width W is within an appropriate range.

If the roll width W is within the appropriate range (S80: YES), the control unit 50 ends the calculation process. If the roll width W is outside the appropriate range (S80: NO), the control unit 50 determines that there is a roll width error and ends the calculation process (S85).

6. Description of Effects This configuration does not rely solely on the detection positions P1, P2 of the solder roll 71 detected by the sensor 26, but also takes into account the printing end position P0 of the squeegee 25 to determine the edge of the solder roll 71 and calculate the roll width W. Therefore, the roll width W of the solder roll 71 can be calculated accurately and robustly.

As shown in FIG. 3B, when the length in the left-right direction of the substrate PX to be printed is small, the stencil 12C in the portion that does not overlap with the substrate PX is bent, and an unscrewed portion 72 is likely to occur. With the configuration of this embodiment, even if an unscrewed portion 72 exists, the roll width W can be accurately calculated.

In this configuration, the sensor 26 can be placed at both ends of the squeegee head 23, which are likely to overlap with the unscraped portion 72 (see FIG. 6), so restrictions on the mounting position of the sensor 26 are alleviated. In addition, even if there is dropped solder 74 near the solder roll 71 (see FIG. 10) or if a corner 75 is formed on the solder roll 71 (see FIG. 11), the roll width W of the solder roll 71 can be calculated with high accuracy without being affected by these.

<Embodiment 2>
A second embodiment will be described with reference to Figures 13 and 14. In the second embodiment, the control unit 50 displays a machine setting screen 14A of the printing device 1 on the display unit 14 of the printing device 1. The machine setting screen 14A includes setting items for the printing device 1 (left column in Figure 13) and display items for the setting contents (right column in Figure 13).

The setting items include "Roll width measurement start point detection method." When the operator operates the input unit 51 to select this item, a selection menu 15 is displayed among the display items in the right column. The selection menu 15 is a menu for selecting the sensor detection position P1 and the print end position P0, and corresponds to the "selection input unit" of the present invention.

When the operator selects either the sensor detection position P1 or the print end position P0 from the selection menu 15, in the subsequent calculation process, the control unit 50 calculates the roll width W by taking the start point selected by the operator as the start point of the solder roll 71.

In this configuration, the operator can freely select the method for detecting the starting point of the solder roll 71, which reduces fluctuations in the roll width W caused by changing the detection method during production.

Figure 14 is a flowchart of the solder roll calculation process. The solder roll calculation process of the second embodiment differs from the solder roll calculation process of the first embodiment in that it includes step S45 instead of steps S50 to S70.

<Embodiment 3>
In the third embodiment, it is automatically determined which of the following two calculation methods is to be used to calculate the roll width W of the solder roll 71 from the start of production until a predetermined judgment number is reached.

(1) Calculation method using the distance H1 between two points (2) Calculation method using the distance H2 between two points

In the following description, the width of the solder roll 71 calculated using method (1) is referred to as the first roll width W1, and the width of the solder roll 71 calculated using method (2) is referred to as the second roll width W2. The internal variable Q is a variable that determines the starting point of the solder roll 71, and is initially set to the detection position P1.

The process of calculating the roll width W will be explained below using the flowchart in FIG. 15. Steps S10 to S40 are the same as in embodiment 1, so the explanation will be omitted.

After the control unit 50 determines the end point of the solder roll 71 in S40, it proceeds to S250.

<Process until the calculation method is determined>
When the process proceeds to S250, the control unit 50 judges the production number X and the internal variable Q. Specifically, it is judged whether the current production number X is equal to or less than the judgment number and the internal variable Q is at the detection position P1.

The initial setting of the internal variable Q is the detection position P1, so during the first production run after production has started, S250: YES is returned and the process moves to S265.

When the process proceeds to S265, the control unit 50 calculates two roll widths W1 and W2. The control unit 50 then determines whether the difference D between the roll widths W1 and W2 is equal to or less than the threshold value TH (S270).

If the difference D is equal to or less than the threshold value (S270: YES), the control unit 50 determines whether the first roll width W1 is appropriate (S275). If the first roll width W1 is appropriate (S275: YES), the calculation process ends.

If the first roll width W1 is appropriate, the internal variable Q is maintained at the detection position P1. Therefore, the calculation process continues as above even when producing the second sheet and onwards.

If S270 and S275 return YES until the number of printed sheets X on the substrate PX reaches the determination number, the control unit 50 determines the calculation method for the roll width W to be calculation method (1). In this case, the internal variable Q is maintained at the detection position P1.

On the other hand, if the difference D is greater than the threshold value TH (S270: NO), the control unit 50 determines whether the second roll width W2 is appropriate (S271).

If the second roll width W2 is appropriate (S271: YES), the control unit 50 determines the calculation method for the second roll width W to be calculation method (2). Accordingly, the control unit 50 changes the internal variable Q from the detection position P1 to the printing end position P0 (S272).

If the roll widths W1 and W2 are not appropriate (S271, S275: NO), a roll width error occurs (S276).

<Processing after determining the calculation method>
If the calculation method (1) is selected, and the production quantity X is equal to or greater than the determination quantity, a NO determination is made in S250. If the calculation method (2) is selected, the internal variable Q becomes the print end position P0, and therefore a NO determination is made in S250. Therefore, in either case, the process proceeds to S280, and the control unit 50 calculates the roll width W according to the internal variable Q.

In other words, when the internal variable Q is the detection position P1, the first roll width W1 is calculated based on the distance H1 between the two points. On the other hand, when the internal variable Q is the printing end position P0, the second roll width W2 is calculated based on the distance H2 between the two points.

Then, it is determined whether the calculated roll width W (W1 or W2) is appropriate (S280). If the roll width W is appropriate (S285: YES), the calculation process ends. If the roll width W is not appropriate (S285: NO), a roll width error is detected (S286).

It is desirable to calculate the roll width W using method (1), which uses the detection results of the sensor 26 for both the start and end points. However, depending on the type of substrate PX to be printed, unscrewed areas 72 may be left behind, and frequent roll width errors may cause disruptions to production. Roll width errors may also occur due to the characteristics of the mask and the characteristics of the solder (including the conditions on that day).

On the other hand, if the roll width W is calculated using method (2) in which the printing end position P0 is used as the starting point, the effects of the unscraped portion 72, etc. can be eliminated.

In this configuration, the method for calculating the roll width W is automatically determined according to the production status (substrate characteristics, mask characteristics, solder characteristics). This makes it possible to suppress the occurrence of roll width errors and improve takt time.

<Embodiment 4>
In the fourth embodiment, which of the first detection method and the second detection method is to be used to detect the starting point of the solder roll 71 is determined based on past production results.

The printing device 1 stores production history information in the memory unit 54. The production history information is information that links the types of boards produced in the past with the calculation method of the roll width W used in the production of that type.

Figure 16 is a flowchart of the solder roll calculation process of embodiment 4. The solder roll calculation process of embodiment 4 differs from the solder roll calculation process of embodiment 3 in the steps from S350 onwards.

After the control unit 50 determines that the end point of the solder roll 71 is the detection position P2 (S40), the process proceeds to S350. In S350, the control unit 50 accesses the memory unit 54 and determines whether there is a production history of the same type of board as the board to be produced this time.

If the memory unit 54 has production history information for the same product type (S355: YES), the control unit 50 reads from the memory unit 54 the detection method for the start point of the solder roll 71 used in the production of the same product type and applies it to the board to be produced (S355). After that, the roll width W is calculated using the applied start point (S360).

If there is no production history of the same product type (S355: NO), the process proceeds to S250 in the third embodiment, where the start point is automatically determined and the roll width W is calculated. Note that the initial setting of the internal variable Q in the fourth embodiment is set to the detection position P1, the same as in the third embodiment.

In this configuration, the method for detecting the start point is determined based on past production records, which increases the reliability of the calculated roll width W. In addition, by using the same detection method for the same product type, fluctuations in the roll width W can be suppressed.

<Embodiment 5>
In the fifth embodiment, when there is a production record of a board under similar production conditions to the board to be produced, the starting point of the solder roll 71 on the board to be produced is detected using the detection method used in the production of the board under similar production conditions.

The printing device 1 stores information on production conditions in addition to production performance information in the memory unit 54. The information on production conditions includes, for example, the following information. The information on production conditions is linked to the type of substrate PX.

(1) Printing control method (squeegee lift angle, printing speed)
(2) Squeegee type (product type, lot number)
(3) Type of solder paste (variety, lot number, date of manufacture)
(4) Board size (5) Mask size (6) Mask elapsed time, manufacturer name

Figure 17 is a flowchart of the solder roll calculation process of embodiment 5. The solder roll calculation process of embodiment 5 differs from the solder roll calculation process of embodiment 4 in the steps from S350 onwards.

If there is no production history information for a board of the same type as the board to be produced this time (S350: NO), the control unit 50 compares the production conditions for the board to be produced with the production conditions for boards of a different type produced in the past.

If there is a production record of a board under production conditions similar to those of the board to be produced (S451: YES), the control unit 50 reads from the memory unit 54 the detection method used for the board under similar production conditions and applies it to the board to be produced (S452). Then, the roll width W is calculated using the applied detection method (S360).

If there is no production history of boards with similar production conditions (S451: NO), the process proceeds to S250 in embodiment 3, where the start point is automatically determined and the roll width W is calculated. Note that the initial setting of the internal variable Q in embodiment 5 is set to the detection position P1, the same as in embodiment 3.

The control unit 50 determines whether the production conditions are "similar" by comparing multiple items included in the production conditions of the board to be produced with boards produced in the past. The criteria for determining whether they are similar include, for example, whether a certain percentage or more of the items included in the production conditions match, or whether the difference in numerical values is smaller than a certain threshold. The operator can set any criteria for determining whether they are similar.

With this configuration, even if there is no production history of the same type of board as the board to be printed, the detection method to be used for production can be automatically determined by selecting a detection method for boards with similar production conditions. This reduces the operator's workload. In addition, since the roll width W can be accurately calculated using the determined starting point, measures can be taken before the amount of solder becomes insufficient or production is stopped due to an error.

<Embodiment 6>
In embodiment 6, the calculation result of the first roll width W1 calculated using the first detection method and the calculation result of the second roll width W2 calculated using the second detection method are displayed on the display unit 14, and the operator is prompted to select the detection method.

Figure 18 is a flowchart of the solder roll calculation process of embodiment 6. The solder roll calculation process of embodiment 6 differs from the solder roll calculation process of embodiment 1 in the steps from S550 onwards.

After the control unit 50 determines that the end point of the solder roll 71 is the detection position P2 (S40), it calculates the roll width W of the solder roll 71 using two calculation methods, the first detection method and the second detection method.

Next, the control unit 50 creates data for graph 17 of the first roll width W1 calculated by the first detection method and the second roll width W2 calculated by the second detection method, and displays it on the display unit 14 (FIG. 19, S555). The horizontal axis of graph 17 is the number of measurements, and the vertical axis is the roll width W.

Next, the control unit 50 determines whether the first roll width W1 and the second roll width W2 are appropriate (S560). If both roll widths W1 and W2 are appropriate (S560: YES), it determines whether the production number X of the substrate PX has reached the determination number (S570).

The number of sheets to be determined is any number equal to or greater than 1. The number of sheets produced, X, is 0 when production begins and is counted up each time a printing process is performed.

If the production quantity X is less than the judgment quantity (S570: NO), the calculation process is terminated, the printed substrate PX is removed from the printing device 1, and the next substrate PX is brought in, and the printing process is carried out.

If the production quantity X is equal to or greater than the judgment quantity (S570: YES), the control unit 50 displays the detection method selection menu 18 on the display unit 14 in addition to the graph 17 (S580).

From the selection menu 18, the operator can select the detection method to be applied to calculate the roll width W in subsequent production runs.

Once a detection method is selected, in subsequent production, the control unit 50 calculates the roll width W using the detection method selected by the operator.

On the other hand, if at least one of the roll widths W1 and W2 is not correct in S560 (S560: NO), a roll width error occurs (S565). Then, an error message is displayed on the display unit 14 (S566).

In this configuration, the operator can refer to graph 17 showing the changes in roll widths W1 and W2, allowing the operator to select a more reliable detection method at any time.

The display unit 14 may be a display device provided in the printing device 1 described above, or a display device connected to the printing device 1 by wire or wirelessly. For example, it may be a display on a tablet terminal carried by an operator, or a display installed in a central control room in a factory. In such a configuration, the operator can select the detection method even if he or she is located away from the printing device 1.

<Embodiment 7>
In the seventh embodiment, an ID unique to the substrate PX, a detection method for the starting point of the solder roll 71 used in the production of the substrate PX, and the calculation result of the roll width W are stored in association with each other.

To be more specific, a different identifier 19 is attached to the surface of the substrate PX for each substrate (see FIG. 2). The identifier 19 is, for example, a barcode, a two-dimensional code, a character string, etc. A substrate ID unique to each substrate is recorded in the identifier 19. The substrate ID can be read from the identifier 19 by the operator visually or by using a reading device. The read substrate ID is input to the control unit 50.

The control unit 50 associates the substrate ID of the produced substrate PX with the calculated roll width W and the start point detection method used in the calculation process, and stores them in the memory unit 54.

An example of the information stored in the memory unit 54 is shown in Figure 20. For each produced board, the board ID, roll width W, and start point detection method are stored in a linked state. With this configuration, even after production has ended, it is possible to access the memory unit 54 and check the process that led to the determination that the roll width W is appropriate, including the detection method.

<Other embodiments>
The present invention is not limited to the embodiments described above and illustrated in the drawings, and for example, the following embodiments are also included within the technical scope of the present invention.
(1) In the above embodiment, the selection menu 15 displayed on the machine setting screen was given as an example of a selection input unit. However, for example, a toggle switch or a push button switch may be used to select either the detection position P1 detected by the sensor 26 or the printing end position P0.

(2) In the above embodiment, when the detection position P1 detected by the sensor 26 is located behind the printing end position P0, the roll width W is calculated using the printing end position P0 as the starting point of the solder roll 71 instead of the detection position P1. The starting point of the solder roll 71 is not limited to the printing end position P0, and may be any position between the detection position P1 and the printing end position P0.

(3) In the above embodiment, the squeegee 25 is moved from rear to front to perform printing, but the direction of squeegee movement is not limited to this. The printing process may be performed by moving the squeegee 25 from front to rear. In this case, the arm portion 29 rotates the squeegee 25 around the pivot shaft 29A to adjust the angle between the stencil 12B and the squeegee 25.

(4) In the above embodiment, the sensor 26 outputs an ON signal when solder is present and outputs an OFF signal when solder is not present. The ON/OFF of the sensor output may be reversed. In other words, an OFF signal may be output when solder is not present and an ON signal may be output when solder is present.

REFERENCE SIGNS LIST 1 Screen printing device 12 Mask 21 Moving device 25 Squeegee 26 Sensor 50 Control unit 70 Solder paste 71 Solder roll PX Substrate P0 Printing end positions P1, P2 Detection position W Roll width

Claims (8)

1. A screen printing apparatus comprising:
With a mask,
A squeegee and
a moving device that moves the squeegee in a front-rear direction on the mask from a printing start position to a printing end position;
a sensor for detecting solder paste on the mask;
A control unit,
The control unit uses the moving device to move the squeegee in a front-back direction on the mask, thereby scraping the solder paste on the upper surface of the mask with the squeegee and printing it on a substrate placed on the lower surface of the mask;
After the printing is completed, the control unit scans the solder roll located in front of the printing completion position in the squeegee movement direction with the sensor to detect both ends of the solder roll,
A screen printing apparatus that calculates a roll width of the solder roll in a front-to-rear direction based on the detected position of the solder roll by the sensor and the printing end position. 2. The screen printing apparatus according to claim 1,
the control unit calculates the roll width using a first detection method in which the detection position on the rear side of the solder roll by the sensor is set as a start point of the solder roll when the detection position on the rear side of the solder roll by the sensor is forward of the printing end position of the squeegee;
The control unit of the screen printing device calculates the roll width using a second detection method in which the printing end position of the squeegee is the starting point of the solder roll when the detection position of the rear side of the solder roll detected by the sensor is behind the printing end position of the squeegee. 2. The screen printing apparatus according to claim 1,
A selection input unit is provided,
the selection input unit allows selection of a first detection method in which the detection position on the rear side of the solder roll by the sensor is set as the start point of the solder roll, or a second detection method in which the printing end position of the squeegee is set as the start point of the solder roll,
The control unit determines a detection method according to an operator's selection. 2. The screen printing apparatus according to claim 1,
The control unit calculates the roll width using both a first detection method in which the detection position on the rear side of the solder roll by the sensor is set as the start point of the solder roll, and a second detection method in which the printing end position of the squeegee is set as the start point of the solder roll,
The control unit determines a detection method for the starting point of the solder roll based on the roll widths calculated using two detection methods until the production number of the substrates reaches a predetermined production number. 2. The screen printing apparatus according to claim 1,
The control unit of the screen printing apparatus determines, based on past production performance, which detection method to use to detect the starting point of the solder roll: a first detection method in which the detection position on the rear side of the solder roll by the sensor is the starting point of the solder roll, or a second detection method in which the printing end position of the squeegee is the starting point of the solder roll. 6. The screen printing apparatus according to claim 5,
The control unit of the screen printing apparatus detects the starting point of the solder roll for the substrate to be produced using a detection method used in the production of the substrate to be produced under similar production conditions when there is a production record of a substrate to be produced under similar production conditions. 2. The screen printing apparatus according to claim 1,
The control unit is
a calculation result of a first roll width calculated by a first detection method in which a detection position on the rear side of the solder roll by the sensor is set as a starting point of the solder roll;
A calculation result of a second roll width calculated by a second detection method in which the printing end position of the squeegee is set as the starting point of the solder roll; and
and a selection menu for the two detection methods is displayed on a display unit of the screen printing device. The screen printing apparatus according to any one of claims 1 to 7,
The control unit of the screen printing device stores in the memory unit a substrate ID unique to the substrate, a detection method for the starting point of the solder roll used in the production of the substrate, and a calculation result of the roll width of the solder roll in the front-to-rear direction, in association with each other.

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