Print quality control system and print quality control method

Abstract

To provide a print quality control system that can correct a relative position of a mask and a substrate for each printing direction before the deviation of solder printed on the substrate from a target printing position reaches a threshold value for determining solder misalignment.SOLUTION: A print quality control system includes an acquisition unit and a correction unit. The acquisition unit acquires, for each printing direction, a deviation of solder printed on a substrate through an opening in the mask by a squeegee sliding over the mask from a target printing position. When the deviation acquired by the acquisition unit exceeds a second threshold set smaller than a first threshold for determining misalignment of the solder, the correction unit corrects a relative position of the mask and the substrate for each printing direction to reduce the deviation.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This specification discloses a technique relating to a print quality control system and a print quality control method. [Background technology]

[0002] The pre-processing unit described in Patent Document 1 executes corrective action in advance when a print defect occurs when the measurement result of the print condition measured by the print inspection machine exceeds a preliminary threshold that is set stricter than the inspection threshold used by the print inspection machine to determine whether the print condition is defective. The print condition measurement result also includes deviation of the solder printed on the board from the target printing position. This allows the print quality control system described in Patent Document 1 to reduce the number of defects determined to be print defects (misaligned solder) by the print inspection machine compared to when no pre-processing is performed.

[0003] Furthermore, the print control unit of the printing device described in Patent Document 2 receives feedback of the inspection result data and, based on the inspection result data, can change the print parameters (print conditions) so as to move the print head or a board holding table moving mechanism that can change the relative position between the board and the screen mask. In this way, the printing device described in Patent Document 2 tries to suppress misalignment of the solder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 024326 [Patent Document 2] Japanese Patent Application Publication No. 2023-173291 Summary of the Invention [Problem to be solved by the invention]

[0005] For example, the mask is attached to a gauze (such as polyester mesh) hung on a frame member, and the tension of the mask may fluctuate as the mask is used. Fluctuations in the mask tension can cause the relative position of the mask and the board to fluctuate, resulting in misalignment of the solder and reduced print quality. Furthermore, the impact of fluctuations in the mask tension may differ depending on the printing direction.

[0006] In light of these circumstances, this specification discloses a print quality control system and a print quality control method that can correct the relative position of the mask and the substrate for each printing direction before the deviation of the solder printed on the substrate from the target printing position reaches a threshold value for determining solder misalignment. [Means for solving the problem]

[0007] This specification discloses a print quality control system including an acquisition unit and a correction unit. The acquisition unit acquires, for each printing direction, a deviation of solder printed on a substrate through an opening in a mask by sliding the mask over the solder, from a target printing position. When the deviation acquired by the acquisition unit exceeds a second threshold value set smaller than a first threshold value for determining misalignment of the solder, the correction unit corrects the relative position of the mask and the substrate for each printing direction to reduce the deviation.

[0008] This specification also discloses a print quality control method including an acquisition step and a correction step. The acquisition step acquires, for each printing direction, a deviation of solder printed on a substrate through an opening in a mask by sliding the squeegee over the mask from a target printing position. The correction step corrects the relative position of the mask and the substrate for each printing direction to reduce the deviation when the deviation acquired by the acquisition step exceeds a second threshold set smaller than a first threshold for determining misalignment of the solder.

[0009] This specification discloses the technical idea of ​​changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 3" in claim 4 of the claims originally attached to the application (hereinafter referred to as "original claims"). This specification also discloses the technical idea of ​​changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 4" in claim 5 of the claims originally attached. This specification also discloses the technical idea of ​​changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 5" in claim 6 of the claims originally attached.

[0010] This specification also discloses the technical idea of ​​changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 6" in claim 7 originally claimed. Furthermore, this specification also discloses the technical idea of ​​changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 7" in claim 8 originally claimed.

[0011] This specification also discloses the technical idea of ​​changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 9" in claim 10 originally claimed in the scope of claims. Furthermore, this specification also discloses the technical idea of ​​changing "the print quality control system according to claim 1" to "the print quality control system according to any one of claims 1 to 11" in claim 12 originally claimed in the scope of claims. [Effects of the Invention]

[0012] According to the above print quality control system, the relative positions of the mask and the board can be corrected for each printing direction before the deviation of the solder printed on the board from the target printing position reaches the threshold value for determining the misalignment of the solder. What has been described above about the print quality control system also applies to the print quality control method. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram showing a configuration example of a substrate-related work line; [Figure 2] FIG. 1 is a partial cross-sectional view showing an example of the configuration of a printing press. [Figure 3] FIG. 2 is a block diagram showing an example of a control block of a print quality control system. [Figure 4] 10 is a flowchart illustrating an example of a control procedure performed by the print quality control system. [Figure 5] 5A to 5C are schematic diagrams showing examples of deviations in a first direction, a second direction, and a rotational direction. [Figure 6] FIG. 10 is a schematic diagram illustrating an example of a setting screen. [Figure 7] FIG. 10 is a schematic diagram showing another example of the setting screen. [Figure 8] FIG. 10 is a schematic diagram showing another example of the setting screen. [Figure 9] FIG. 10 is a schematic diagram showing another example of the setting screen. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1. Embodiment 1-1. Example of the configuration of the board-to-board work line WL0 In the substrate-related work line WL0, a substrate-related work machine WM0 performs a predetermined substrate-related work on a substrate 90. The substrate-related work line WL0 of the embodiment only needs to be equipped with a printer WM1 and a print inspection machine WM2, and the type and number of substrate-related work machines WM0 constituting the substrate-related work line WL0 are not limited. As shown in Fig. 1, the substrate-related work line WL0 of the embodiment is equipped with a plurality (five) of substrate-related work machines WM0, including a printer WM1, a print inspection machine WM2, a component mounting machine WM3, a reflow oven WM4, and a visual inspection machine WM5, and the substrate 90 is transported in this order by a substrate transport device.

[0015] The printer WM1 prints solder 80 at the mounting positions of multiple components on the board 90. The print inspection machine WM2 inspects the printing condition of the solder 80 printed by the printer WM1. The component mounting machine WM3 mounts multiple components on the board 90 on which the solder 80 has been printed by the printer WM1. There may be one or more component mounting machines WM3. When multiple component mounting machines WM3 are provided, the multiple component mounting machines WM3 can share the mounting work of multiple components.

[0016] The reflow furnace WM4 heats the board 90 on which multiple components have been mounted by the component mounting machine WM3, melting the solder 80 and performing soldering. The visual inspection machine WM5 inspects the mounting state of the multiple components mounted by the component mounting machine WM3. In this way, the board-related work line WL0 uses multiple (five) board-related work machines WM0 to sequentially transport the boards 90 and perform production processes including inspection processes to produce the product board 900. Note that the board-related work line WL0 can also be equipped with board-related work machines WM0 such as a function inspection machine, a buffer device, a board supply device, a board inverting device, a shield mounting device, an adhesive application device, and an ultraviolet irradiation device as needed.

[0017] The plurality (five) of substrate-related performing machines WM0 and the control device WC0 that make up the substrate-related performing line WL0 are communicatively connected by a communication unit LC0. The communication unit LC0 may perform communication via a wired connection or wirelessly. Various communication methods may be used. In this embodiment, the plurality (five) of substrate-related performing machines WM0 and the control device WC0 form an in-house information and communication network (LAN: Local Area Network). This allows the plurality (five) of substrate-related performing machines WM0 to communicate with each other via the communication unit LC0. Furthermore, the plurality (five) of substrate-related performing machines WM0 can communicate with the control device WC0 via the communication unit LC0.

[0018] The management device WC0 controls the multiple (five) substrate-related performing machines WM0 that make up the substrate-related performing line WL0 and monitors the operating status of the substrate-related performing line WL0. The management device WC0 stores various control data for controlling the multiple (five) substrate-related performing machines WM0. The management device WC0 transmits the control data to each of the multiple (five) substrate-related performing machines WM0. Furthermore, each of the multiple (five) substrate-related performing machines WM0 transmits its operating status and production status to the management device WC0.

[0019] The management device WC0 may be provided with a data server DS0. The data server DS0 may store, for example, acquired data acquired by the substrate-related performing machine WM0 regarding substrate-related performing operations. For example, various image data captured by the substrate-related performing machine WM0 is included in the acquired data. The acquired data may also include records (log data) of the operating status acquired by the substrate-related performing machine WM0.

[0020] In addition to the image data and operational status records (log data), the data server DS0 can also store various production information related to the production of the product board 900. For example, component data such as information on the shape of each component type, information on electrical characteristics, and information on how to handle the components is included in the production information. In addition, the production information includes inspection results from inspection machines such as the print inspection machine WM2 and the appearance inspection machine WM5.

[0021] 1-2. Configuration example of printing machine WM1 In the printer WM1 of this embodiment, the squeegee 34 slides over the mask 70 to print solder 80 onto the substrate 90 through the openings 71 in the mask 70. As shown in FIG. 2, the printer WM1 includes a substrate transport device 10, a mask support device 20, a squeegee moving device 30, a control device 40, and a display device 41. In this specification, the transport direction of the substrate 90 (a direction perpendicular to the paper surface of FIG. 2) is defined as the X direction. Furthermore, the front-to-rear direction of the printer WM1 (the left-to-right direction in FIG. 2) perpendicular to the X direction in a horizontal plane is defined as the Y direction. The Y direction corresponds to the printing direction. Furthermore, the vertical direction perpendicular to the X and Y directions (the up-and-down direction in FIG. 2) is defined as the Z direction.

[0022] The board transfer device 10 transfers a board 90 to be printed. The board 90 is a circuit board on which various circuits such as electronic circuits, electric circuits, and magnetic circuits are formed. The board transfer device 10 is provided on a base BS0 of the printing machine WM1. The board transfer device 10 transfers the board 90, for example, by a belt conveyor extending in the transfer direction (X direction) of the board 90.

[0023] The substrate transport device 10 includes a substrate holding unit 11 that holds the substrate 90 that has been carried into the printing machine WM1. The substrate holding unit 11 is provided below the mask 70 and is configured to be able to move up and down in the vertical direction (Z direction) by, for example, a linear motion mechanism such as a feed screw mechanism. Specifically, the substrate holding unit 11 is lowered when the substrate 90 is transported, and when the substrate 90 is transported to a predetermined position, it rises together with the substrate 90 and holds the substrate 90 with the upper surface of the substrate 90 in close contact with the lower surface of the mask 70.

[0024] The mask support device 20 is provided above the substrate transport device 10. The mask support device 20 supports the mask 70 by a pair of support tables. The pair of support tables are arranged on the left side (the back side of the paper in FIG. 2 and shown in the figure) and the right side (the front side of the paper in FIG. 2 and not shown in the figure) of the printing machine WM1 when viewed from the front, and are formed to extend along the printing direction (Y direction).

[0025] 2 is a partial cross-sectional view of the printer WM1 cut along the printing direction (Y direction), and schematically shows the inside of the printer WM1 as viewed from the side, and cross sections of the mask 70 and the substrate 90. The mask 70 has openings 71 formed therethrough at predetermined positions on the wiring pattern of the substrate 90. The mask 70 is supported by the mask support device 20, for example, via a frame member provided on the outer periphery.

[0026] The squeegee moving device 30 raises and lowers the squeegee 34 in a vertical direction (Z direction) perpendicular to the mask 70, and moves the squeegee 34 in the printing direction (Y direction) on the top surface of the mask 70. The squeegee moving device 30 includes a head driving device 31, a squeegee head 32, a pair of lifting and lowering devices 33, 33, and a pair of squeegees 34, 34. The head driving device 31 is disposed on the upper side of the printing machine WM1. The head driving device 31 can move the squeegee head 32 in the printing direction (Y direction) by, for example, a linear motion mechanism such as a feed screw mechanism.

[0027] The squeegee head 32 is clamped and fixed to a moving body that constitutes the linear motion mechanism of the head drive device 31. The squeegee head 32 holds a pair of lifting devices 33, 33. Each of the pair of lifting devices 33, 33 holds a squeegee 34 and can be driven independently of each other. Each of the pair of lifting devices 33, 33 drives an actuator such as an air cylinder to raise and lower the squeegee 34 that it holds.

[0028] The squeegee 34 slides over the upper surface of the mask 70, moving the solder 80 supplied to the upper surface of the mask 70 along the mask 70. Cream solder (solder paste) can be used as the solder 80. The solder 80 is imprinted onto the substrate 90 through the openings 71 in the mask 70, and is printed on the substrate 90 arranged below the mask 70. In this embodiment, each of the pair of squeegees 34, 34 is a plate-like member formed to extend along the transport direction (X direction) of the substrate 90, which is perpendicular to the printing direction (Y direction).

[0029] The front squeegee 34 (left side of the paper in FIG. 2) of the pair of squeegees 34 is used in a printing process that moves the solder 80 from the front side to the rear side (right side of the paper in FIG. 2), with the direction from the front side to the rear side of the printer WM1 being the traveling direction. The rear squeegee 34 of the pair of squeegees 34 is used in a printing process that moves the solder 80 from the rear side to the front side, with the direction from the rear side to the front side of the printer WM1 being the traveling direction. Furthermore, for both squeegees 34, the direction opposite to the traveling direction is the retreating direction.

[0030] Each of the pair of squeegees 34, 34 is held by the lifting device 33 at an inclination such that the front portion located on the traveling direction side faces downward. In other words, each of the pair of squeegees 34, 34 is held by the lifting device 33 at an inclination such that the back portion located on the retreating direction side faces upward. The inclination angle of each of the pair of squeegees 34, 34 can be adjusted by, for example, an adjustment mechanism provided at the bottom of the lifting device 33.

[0031] The control device 40 includes a known arithmetic unit and storage device, and forms a control circuit. The control device 40 is communicably connected to the management device WC0 via the communication unit LC0 shown in FIG. 1, and can send and receive various data. The control device 40 can drive and control the substrate transport device 10, mask support device 20, squeegee moving device 30, and display device 41 based on the production program, detection results of various sensors, etc.

[0032] The control device 40 is provided with a storage device. The storage device may be, for example, a magnetic storage device such as a hard disk drive, or a storage device using semiconductor elements such as flash memory. The storage device stores a production program for driving the printing press WM1. The control device 40 acquires various pieces of information stored in the storage device and detection results of various sensors provided on the printing press WM1.

[0033] The control device 40, for example, drives and controls the squeegee moving device 30. The control device 40 sends a control signal to the squeegee moving device 30 based on the above-mentioned various information and detection results, etc. This controls the positions (heights) of the pair of squeegees 34, 34 held by the squeegee head 32 in the printing direction (Y direction) and in the vertical direction (Z direction), as well as the movement speed and tilt angle. Then, the pair of squeegees 34, 34 are driven and controlled as described above, and solder 80 is printed on the substrate 90 arranged on the underside of the mask 70.

[0034] As shown in FIG. 2, the control device 40 is provided with a display device 41. The display device 41 can display the working status of the printing press WM1. The display device 41 is also configured with a touch panel and also functions as an input device that accepts various operations by the worker. The worker can know the working status of the printing press WM1 via the display device 41. The worker can also set the printing press WM1, give instructions to the printing press WM1, etc. via the display device 41.

[0035] 1-3. Example of the configuration of the print quality control system 50 There is a demand to correct the relative position of the mask 70 and the substrate 90 before the deviation PD0 of the solder 80 printed on the substrate 90 from the target printing position PG0 reaches the threshold value for determining the misalignment of the solder 80, thereby reducing the number of defects determined to be due to poor printing conditions (misalignment of the solder 80) by the print inspection machine WM2.

[0036] Furthermore, for example, the mask 70 is provided on a gauze (such as a polyester mesh) hung on a frame member, and the tension of the mask 70 may fluctuate as the mask 70 is used. If the tension of the mask 70 fluctuates, the relative positions of the mask 70 and the substrate 90 may fluctuate, causing misalignment of the solder 80 and reducing print quality. The impact of fluctuations in the tension of the mask 70 may differ depending on the printing direction.

[0037] Therefore, the substrate-related work line WL0 of this embodiment is provided with a print quality control system 50. With the print quality control system 50, the relative position of the mask 70 and the substrate 90 can be corrected for each printing direction (Y direction) before the deviation PD0 of the solder 80 printed on the substrate 90 from the target printing position PG0 reaches a threshold value used to determine the positional misalignment of the solder 80. When considered as a control block, the print quality control system 50 includes an acquisition unit 51 and a correction unit 52. The print quality control system 50 can also include a pre-processing unit 53. The print quality control system 50 can also include a setting unit 54.

[0038] 3, print quality control system 50 of the embodiment includes an acquisition unit 51, a correction unit 52, a pre-processing unit 53, and a setting unit 54. Acquisition unit 51, correction unit 52, pre-processing unit 53, and setting unit 54 can be provided in various control devices and management devices such as substrate-related performing machine WM0 and management device WC0. Furthermore, acquisition unit 51, correction unit 52, pre-processing unit 53, and setting unit 54 can also be formed on the cloud.

[0039] Furthermore, the acquisition unit 51, correction unit 52, pre-processing unit 53, and setting unit 54 can be distributed and located in various control devices, management devices, on the cloud, etc. For example, the acquisition unit 51 can be located in the print inspection machine WM2, the correction unit 52 and pre-processing unit 53 can be located in the printing machine WM1, and the setting unit 54 can be located in both the printing machine WM1 and the print inspection machine WM2. As shown in Figure 3, in this embodiment, the acquisition unit 51, correction unit 52, pre-processing unit 53, and setting unit 54 are provided in the management device WC0.

[0040] The print quality control system 50 also executes control in accordance with the flowchart shown in FIG. 4. The acquisition unit 51 performs the processes and judgments shown in steps S11 to S14. The correction unit 52 performs the processes and judgments shown in steps S15 and S16. The pre-processing unit 53 performs the processes and judgments shown in steps S17 to S20. The setting unit 54 prompts the user of the printing press WM1 to set a threshold value, which will be described later, before executing the control shown in FIG. 4. The matters described in this specification can be selected and applied as appropriate. The matters described in this specification can be combined as appropriate.

[0041] 1-3-1. Acquisition part 51 The acquisition unit 51 acquires the deviation PD0 of the solder 80 printed on the substrate 90 through the openings 71 of the mask 70 as the squeegee 34 slides over the mask 70, from the target printing position PG0, for each printing direction (Y direction) (steps S11 to S14 shown in FIG. 4). The acquisition unit 51 may take various forms as long as it can acquire the deviation PD0 for each printing direction (Y direction).

[0042] For example, the printer WM1 described above has a squeegee 34 that slides over a mask 70 to print solder 80 onto a substrate 90 through openings 71 in the mask 70. The print inspection machine WM2 can then inspect the deviation PD0 of each pad from the target printing position PG0 of the solder 80 printed on the substrate 90 by the printer WM1. Therefore, the acquisition unit 51 can acquire the inspection results of the print inspection machine WM2 and obtain the deviation PD0 for each pad.

[0043] FIG. 5 shows an example of deviation PD0 of solder 80 printed on a substrate 90. The figure schematically shows the solder 80 when the substrate 90 is viewed from the vertical direction (Z direction). The target printing position PG0 indicates the center position of a target area 80g, such as a pad, when the solder 80 is ideally printed on the target area 80g without any misalignment of the solder 80. For example, the target area 80g in the figure is rectangular, and the center position of the rectangle corresponds to the target printing position PG0.

[0044] As previously mentioned, the tension of the mask 70 may fluctuate. As a result, the relative positions of the mask 70 and the substrate 90 may fluctuate, potentially causing misalignment of the solder 80. The actual printing position PR0 in the figure indicates the center position of the area of ​​the solder 80 actually printed on the substrate 90. The area of ​​the solder 80 in the figure is rectangular, and the center position of the rectangle corresponds to the actual printing position PR0.

[0045] As shown in the figure, the deviation PD0 of the solder 80 printed on the substrate 90 from the target printing position PG0 can be expressed by a vector pointing from the target printing position PG0 to the actual printing position PR0 in the horizontal plane formed by the first direction (α direction) and the second direction (β direction). In addition, the deviation PD0 of the solder 80 printed on the substrate 90 from the target printing position PG0 can include a component in the rotational direction of one of the mask 70 and the substrate 90 relative to the other.

[0046] In other words, the deviation PD0 of the solder 80 printed on the substrate 90 from the target printing position PG0 may include at least one of the deviation PD0 in the first direction (α direction), the deviation PD0 in the second direction (β direction), and the deviation PD0 in the rotational direction (θ direction). The deviation PD0 in the first direction (α direction) refers to the component of the deviation PD0 that is along the printing direction (Y direction). The deviation PD0 in the second direction (β direction) refers to the component of the deviation PD0 that is perpendicular to the first direction (α direction) on the horizontal plane.

[0047] As already described, in the embodiment, the second direction (β direction) corresponds to the transport direction (X direction) of the substrate 90. The deviation PD0 in the rotational direction (θ direction) refers to the component of the deviation PD0 in the rotational direction of one of the mask 70 and the substrate 90 relative to the other. The deviation PD0 shown in Fig. 5 includes all of the deviation PD0 in the first direction (α direction), the deviation PD0 in the second direction (β direction), and the deviation PD0 in the rotational direction (θ direction).

[0048] Typically, a single substrate 90 has multiple pads formed thereon, and solder 80 is printed on each of the multiple pads. The acquisition unit 51 acquires the deviation PD0 for each of the above components for the solder 80 printed on each of the multiple pads on the single substrate 90. The acquisition unit 51 then calculates, for example, an average value of the deviations PD0 for each component, and can use the calculated average value of the deviations PD0 as the deviation PD0 for each component on the single substrate 90.

[0049] Furthermore, the acquisition unit 51 can calculate, for example, an average value of the deviations PD0 for each component for at least one specific pad among the multiple pads, and use the calculated average value of the deviations PD0 as the deviation PD0 for each component on one board 90. The specific pad can be set arbitrarily. For example, the specific pad can include pads on which components, such as integrated circuits, having a relatively short electrode pitch and requiring relatively strict printing quality, are mounted.

[0050] Furthermore, when the acquisition unit 51 acquires the deviation PD0 from one board 90, the stability of the acquired deviation PD0 is likely to decrease. Therefore, the acquisition unit 51 may acquire the deviation PD0 for a predetermined number of boards 90 for each printing direction (Y direction) and use the average value of the acquired deviations PD0 as the deviation PD0 for each printing direction (Y direction) (steps S11 to S13 shown in FIG. 4). In this case, the acquisition unit 51 can acquire the deviation PD0 in the same way as when acquiring the deviation PD0 from one board 90.

[0051] The predetermined number corresponds to the number of sampling sheets KN0, which will be described later, and can be set arbitrarily. The larger the predetermined number, the greater the number of samples, making it easier for the acquired deviation PD0 to stabilize, but the longer the time required to acquire the deviation PD0. Therefore, the predetermined number can be set based on the required stability of the deviation PD0 and the allowable required time. For example, the predetermined number can be set to several sheets (e.g., three sheets). Furthermore, as will be described later, the predetermined number (number of sampling sheets KN0) can also be set by the user of the printing press WM1.

[0052] If the printing direction (Y direction) is different, the state of the mask 70 may vary. For example, as shown in FIGS. 2 and 5, the printing direction (Y direction) may include an outgoing direction (Y1 direction) and a returning direction (Y2 direction). The outgoing direction (Y1 direction) refers to the printing direction when the squeegee 34 slides in one direction on the mask 70. The returning direction (Y2 direction) refers to the printing direction when the squeegee 34 slides in the opposite direction to the outgoing direction (Y1 direction) on the mask 70.

[0053] As described above, for example, in the printer WM1 shown in FIG. 2, when the printing direction (Y direction) is the outward direction (Y1 direction), the squeegee 34 on the front side (left side of the paper in FIG. 2) moves the solder 80 from the front side to the rear side (right side of the paper in FIG. 2) to print the solder 80 on the substrate 90. In this case, the rear side of the mask 70 is likely to twist, and the tension on the front side is likely to be higher than that on the rear side. Conversely, when the printing direction (Y direction) is the backward direction (Y2 direction), the squeegee 34 on the rear side (right side of the paper in FIG. 2) moves the solder 80 from the rear side to the front side to print the solder 80 on the substrate 90. In this case, the front side of the mask 70 is likely to twist, and the tension on the rear side is likely to be higher than that on the front side.

[0054] In this way, if the printing direction (Y direction) differs, the state of the mask 70 may vary. Therefore, the acquisition unit 51 acquires the deviation PD0 of the solder 80 printed on the board 90 from the target printing position PG0 for each printing direction (Y direction) (steps S11 to S14 shown in FIG. 4). In other words, the acquisition unit 51 acquires the deviation PD0 when the printing direction (Y direction) is the forward direction (Y1 direction). The acquisition unit 51 also acquires the deviation PD0 when the printing direction (Y direction) is the backward direction (Y2 direction).

[0055] The above also applies to the case where the acquisition unit 51 acquires the deviation PD0 for a predetermined number of substrates 90. In other words, when the printing direction (Y direction) is the forward pass direction (Y1 direction), the acquisition unit 51 acquires the deviation PD0 for the predetermined number of substrates 90 and sets the average value of the acquired deviations PD0 as the deviation PD0 in the forward pass direction (Y1 direction). Furthermore, when the printing direction (Y direction) is the backward pass direction (Y2 direction), the acquisition unit 51 acquires the deviation PD0 for the predetermined number of substrates 90 and sets the average value of the acquired deviations PD0 as the deviation PD0 in the backward pass direction (Y2 direction).

[0056] It is possible that the mask 70 may have a partially deteriorated gauze (such as polyester mesh) hung on the frame member, resulting in a partial decrease in tension. Therefore, the deviation PD0 may include at least one of the deviation PD0 in the second direction (β direction) and the deviation PD0 in the rotational direction (θ direction) in addition to the deviation PD0 in the first direction (α direction) that is along the printing direction (Y direction).

[0057] 1-3-2. Correction unit 52 When the deviation PD0 acquired by the acquisition unit 51 exceeds a second threshold TH2 that is set smaller than the first threshold TH1 for determining misalignment of the solder 80, the correction unit 52 corrects the relative positions of the mask 70 and the substrate 90 for each printing direction (Y direction) so as to reduce the deviation PD0 (step S16 shown in FIG. 4). This allows the correction unit 52 to correct the relative positions of the mask 70 and the substrate 90 before the deviation PD0 reaches the threshold (first threshold TH1) for determining misalignment of the solder 80.

[0058] The correction unit 52 may take various forms as long as it can correct the relative position of the mask 70 and the substrate 90 for each printing direction (Y direction) as described above. As described above, for example, the deviation PD0 may include at least one of the deviation PD0 in the first direction (α direction), the deviation PD0 in the second direction (β direction), and the deviation PD0 in the rotational direction (θ direction). Therefore, the correction unit 52 corrects at least one of the deviation PD0 in the first direction (α direction), the deviation PD0 in the second direction (β direction), and the deviation PD0 in the rotational direction (θ direction).

[0059] 5, a positive deviation PD0 occurs in the first direction (α direction). The first direction (α direction) is a direction along the printing direction (Y direction) and includes, for example, a forward direction (Y1 direction) that is a positive direction and a backward direction (Y2 direction) that is a negative direction. Therefore, in this case, the correction unit 52 moves one of the mask 70 and the substrate 90 relative to the other in the backward direction (Y2 direction) that is the negative direction of the first direction (α direction) so as to reduce the positive deviation PD0 in the first direction (α direction).

[0060] 2 is lowered when the substrate 90 is transported, and when the substrate 90 is transported to a predetermined position, it rises together with the substrate 90 and holds the substrate 90 with the upper surface of the substrate 90 in close contact with the lower surface of the mask 70. In other words, the printing machine WM1 of the embodiment can move the substrate 90 relative to the fixed mask 70. Furthermore, the substrate holding unit 11 can move in the transport direction (X direction) of the substrate 90, the printing direction (Y direction), and the vertical direction (Z direction), and can also rotate.

[0061] Therefore, in the above example, the correction unit 52 moves the substrate holding unit 11 together with the substrate 90 in the backward direction (Y2 direction) by the correction amount, and then raises the substrate holding unit 11 together with the substrate 90. Then, the correction unit 52 causes the substrate holding unit 11 to hold the substrate 90 with the upper surface of the substrate 90 in close contact with the lower surface of the mask 70. This reduces the positive deviation PD0 in the first direction (α direction). The correction unit 52 can also reduce the negative deviation PD0 in the first direction (α direction) in a similar manner. The correction unit 52 can also reduce the deviation PD0 in the second direction (β direction) in a similar manner. Furthermore, the correction unit 52 can also reduce the deviation PD0 in the rotational direction (θ direction) in a similar manner.

[0062] Note that when the substrate 90 is carried into the printing press WM1, if the stopping position of the substrate 90 deviates from the target stopping position, the deviation PD0 described above occurs. Therefore, as shown in Fig. 2, the printing press WM1 of this embodiment is provided with an imaging device FC0. The imaging device FC0 can move in the conveying direction (X direction) and printing direction (Y direction) of the substrate 90 by, for example, an XY table, and can capture images of the positioning reference portions provided on the mask 70 and the substrate 90.

[0063] Specifically, when the substrate 90 is transported while the substrate holder 11 is in a lowered state, the imaging device FC0 moves to a positioning reference portion provided on the substrate 90 and captures an image of a predetermined area of ​​the substrate 90 including the positioning reference portion. Similarly, the imaging device FC0 captures an image of a predetermined area including the positioning reference portion of the mask 70. The control device 40 processes the captured image to recognize the positioning reference portion of the substrate 90 and the positioning reference portion of the mask 70. The control device 40 adjusts the position of at least one of the mask 70 and the substrate 90 to correct the positional misalignment between them. This corrects the deviation between the target stop position and the actual stop position of the substrate 90.

[0064] Furthermore, if an attempt is made to eliminate the deviation PD0 acquired by the acquisition unit 51 all at once, the amount of correction is likely to become large. The larger the correction amount, the more likely it is that overshoot will occur, in which the amount of movement of one of the mask 70 and the substrate 90 relative to the other becomes larger than necessary, and control may become unstable. Therefore, it is preferable that the correction unit 52 gradually correct the relative positions of the mask 70 and the substrate 90 by an amount of correction smaller than the deviation PD0 acquired by the acquisition unit 51.

[0065] For example, the correction unit 52 can set the multiplied value obtained by multiplying the deviation PD0 acquired by the acquisition unit 51 by a predetermined reflection rate RP0 as the correction amount. The reflection rate RP0 can be set to any rate less than 100%. As will be described later, the reflection rate RP0 can also be set by the user of the printing machine WM1. By setting the reflection rate RP0 to a value less than 100%, the multiplied value (correction amount) becomes smaller than the deviation PD0 acquired by the acquisition unit 51. By repeating the processes and determinations shown in steps S11 to S16 in FIG. 4, the correction unit 52 can gradually correct the relative positions of the mask 70 and the substrate 90 by a correction amount smaller than the deviation PD0 acquired by the acquisition unit 51.

[0066] Furthermore, the first threshold value TH1 used to determine misalignment of the solder 80 and the second threshold value TH2, which is set smaller than the first threshold value TH1, can be set arbitrarily. As described below, for example, at least one of the first threshold value TH1 and the second threshold value TH2 can be set by the user of the printer WM1. Furthermore, the printer WM1 has a minimum correction amount MC0 that can correct the relative position of the mask 70 and the board 90, and it is difficult for the correction unit 52 to correct the relative position of the mask 70 and the board 90 with a correction amount smaller than the minimum correction amount MC0.

[0067] Therefore, the correction unit 52 may correct the relative positions of the mask 70 and the substrate 90 when the deviation PD0 acquired by the acquisition unit 51 is larger than the minimum correction amount MC0 by which the relative positions of the mask 70 and the substrate 90 can be corrected. In other words, the correction unit 52 does not correct the relative positions of the mask 70 and the substrate 90 when the deviation PD0 acquired by the acquisition unit 51 is smaller than the minimum correction amount MC0 by which the relative positions of the mask 70 and the substrate 90 can be corrected. In this way, the correction unit 52 can use the minimum correction amount MC0 as the second threshold value TH2.

[0068] As described above, the correction unit 52 can correct at least one of the deviation PD0 in the first direction (α direction), the deviation PD0 in the second direction (β direction), and the deviation PD0 in the rotational direction (θ direction). Therefore, the minimum correction amount MC0 can include at least one of the minimum correction amount MC1 in the first direction (α direction), the minimum correction amount MC2 in the second direction (β direction), and the minimum correction amount MC3 in the rotational direction (θ direction). As described below, the minimum correction amount MC0 can also be set by the user of the printing press WM1. Furthermore, the correction unit 52 can also use an arbitrary threshold value between the minimum correction amount MC0 and the first threshold value TH1 as the second threshold value TH2.

[0069] Furthermore, if the area SH0 of the solder 80 is extremely small or extremely large, it may be erroneously recognized that the solder 80 is misaligned, even though there is no misalignment of the solder 80. For example, consider a case where the solder 80 is printed in the right half of the target area 80g shown in Figure 5. In this case, the solder 80 is printed within the target area 80g, and no misalignment of the solder 80 has occurred.

[0070] However, the center position of the right half of the target area 80g shown in Figure 5 has moved to the right on the paper surface relative to the target print position PG0. As a result, the actual print position PR0 has moved to the right on the paper surface relative to the target print position PG0, and there is a possibility that misalignment of the solder 80 has occurred, even though there is no misalignment of the solder 80. What has been described above regarding the case where the area SH0 of the solder 80 is extremely small also applies to the case where the area SH0 of the solder 80 is extremely large.

[0071] Therefore, the acquisition unit 51 may acquire the area SH0 of the solder 80 printed on the board 90. Then, the correction unit 52 may correct the relative position of the mask 70 and the board 90 when the area SH0 of the solder 80 acquired by the acquisition unit 51 is included in an allowable range SR0 set based on the target area SG0 (steps S15 and S16 shown in FIG. 4). The print inspection machine WM2 can inspect the area SH0 of the solder 80 printed on the board 90 by the printer WM1 for each pad. Therefore, the acquisition unit 51 can acquire the inspection results of the print inspection machine WM2 and acquire the area SH0 of the solder 80 for each pad.

[0072] Furthermore, the target area SG0 corresponds to the area of ​​the target region 80g shown in FIG. 5. Furthermore, the allowable range SR0 may be any range that does not cause the above-mentioned erroneous recognition, and the lower limit value SR1 and upper limit value SR2 of the allowable range SR0 can be set arbitrarily. For example, the lower limit value SR1 and upper limit value SR2 can be set evenly around the target area SG0. Specifically, the lower limit value SR1 can be set to, for example, 90% of the target area SG0, and the upper limit value SR2 can be set to, for example, 110% of the target area SG0. Furthermore, as described below, for example, at least one of the lower limit value SR1 and the upper limit value SR2 can be set by the user of the printing press WM1.

[0073] 1-3-3. Pre-processing unit 53 As already described, the acquisition unit 51 can acquire the area SH0 of the solder 80 printed on the substrate 90. The predetermined condition is that the area SH0 of the solder 80 acquired by the acquisition unit 51 is not included in the allowable range SR0 set based on the target area SG0, and the area SH0 is smaller than a preliminary threshold TH4 that is set larger than the threshold TH3 when determining whether the solder 80 is faded.

[0074] When the above-described predetermined conditions are satisfied, the pre-processing unit 53 executes in advance the countermeasure process that should be executed when thinning of the solder 80 occurs (steps S17 and S18 shown in FIG. 4). As a result, the pre-processing unit 53 can execute in advance the countermeasure process that should be executed when thinning of the solder 80 occurs before the area SH0 of the solder 80 acquired by the acquiring unit 51 reaches the threshold value TH3 for determining thinning of the solder 80.

[0075] The threshold value TH3 and the preliminary threshold value TH4 can be set arbitrarily, similar to the first threshold value TH1 and the second threshold value TH2. As described below, at least one of the threshold value TH3 and the preliminary threshold value TH4 can also be set by the user of the printing machine WM1. The threshold value TH3 can be set to, for example, 50% of the target area SG0, and the preliminary threshold value TH4 can be set to, for example, 60% of the target area SG0. The pre-processing unit 53 can also execute various countermeasures. For example, clogging of the openings 71 of the mask 70 is expected to be a cause of the thinning of the solder 80.

[0076] Therefore, it is preferable that the pre-processing unit 53 performs wet cleaning of the mask 70 as a countermeasure. Wet cleaning refers to a wet cleaning method in which, for example, alcohol or the like is applied to the mask 70 for cleaning. The pre-processing unit 53 can also use wet cleaning in combination with dry cleaning (a dry cleaning method) as needed. Furthermore, the pre-processing unit 53 can also use vacuum (a suction-type cleaning method in which residues remaining in the openings 71 are sucked and cleaned) as needed.

[0077] Furthermore, the specified condition is that the area SH0 of the solder 80 acquired by the acquisition unit 51 is not included in the allowable range SR0 set based on the target area SG0, and the area SH0 is larger than a preliminary threshold TH6 set smaller than the threshold TH5 used to determine whether the solder 80 has bled or bridged. When the specified condition is met, the pre-processing unit 53 executes in advance the corrective action that should be taken when the solder 80 has bled or bridged (steps S19 and S20 shown in FIG. 4). In this way, the pre-processing unit 53 can execute in advance the corrective action that should be taken when the solder 80 has bled or bridged, before the area SH0 of the solder 80 acquired by the acquisition unit 51 reaches the threshold TH5 used to determine whether the solder 80 has bled or bridged.

[0078] The threshold value TH5 and the preliminary threshold value TH6 can be set arbitrarily, similar to the first threshold value TH1 and the second threshold value TH2. As will be described later, at least one of the threshold value TH5 and the preliminary threshold value TH6 can also be set by the user of the printing press WM1. The threshold value TH5 can be set to, for example, 150% of the target area SG0, and the preliminary threshold value TH6 can be set to, for example, 140% of the target area SG0. The pre-processing unit 53 can also execute various countermeasures.

[0079] The cause of the oozing or bridging of the solder 80 is expected to be, for example, contamination of the mask 70. Therefore, as a countermeasure, the pre-processing unit 53 may perform dry cleaning of the mask 70. The pre-processing unit 53 may also use both wet cleaning and dry cleaning as needed. The pre-processing unit 53 may also use vacuum as needed.

[0080] 1-3-4.Settings section 54 The setting unit 54 allows a user of the printer WM1 that prints the solder 80 on the substrate 90 to set a predetermined threshold value including at least one of a first threshold value TH1 and a second threshold value TH2. The setting unit 54 may take various forms as long as it allows a user of the printer WM1 to set a predetermined threshold value.

[0081] For example, the setting unit 54 can allow the user of the printing press WM1 to set a predetermined threshold value using the display device 41 of the printing press WM1. The setting unit 54 can also allow the user of the printing press WM1 to set a predetermined threshold value using the display device of the print inspection machine WM2. The setting unit 54 can also allow the user of the printing press WM1 to set a predetermined threshold value using the display device of the management device WC0. As described above, for example, the display device 41 of the printing press WM1 is configured with a touch panel. For example, the user can display the work phase on the display device 41 by operating the operation units BP11 to BP41 surrounded by the dashed line BL1 in Figures 6 to 8.

[0082] When the user operates operation unit BP11, the display device 41 displays the work in the production program creation stage. When the user operates operation unit BP21, the display device 41 displays the work in the production stage. When the user operates operation unit BP31, the display device 41 displays the work in the cleanup stage. When the user operates operation unit BP41, the display device 41 displays the work in the error occurrence stage.

[0083] In addition, the user can display the work status, setting screen, etc. in each work phase by operating operation units BP22 to BP24, which are surrounded by dashed line BL2. What has been described above about the display device 41 of the printing press WM1 can also be similarly applied to other display devices such as the print inspection machine WM2.

[0084] 6 shows an example of a setting screen. By operating operation area BP51, the user can set the allowable range SR0 of the area SH0 of the solder 80, whether or not to correct the relative positions of the mask 70 and the board 90, and so on. Specifically, the user inputs the lower limit SR1 and upper limit SR2 of the allowable range SR0 of the area SH0 of the solder 80 as percentages. The user also selects whether or not to correct the relative positions of the mask 70 and the board 90.

[0085] 7 shows another example of the setting screen. By operating the operation area BP51, the user can set whether or not to perform correction in the next and subsequent production runs, the number of substrates 90 sampled KN0, the correction amount reflection rate RP0, the minimum correction amount MC0, and so on. Specifically, the user selects whether or not to perform correction in the next and subsequent production runs. Furthermore, the user inputs the predetermined number of substrates 90 sampled KN0 when the acquisition unit 51 acquires the deviation PD0.

[0086] Furthermore, for the correction amount reflection rate RP0, the user inputs, as a percentage, the reflection rate RP0 by which the deviation PD0 acquired by the acquisition unit 51 is multiplied. Furthermore, for the minimum correction amount MC0, the user inputs a minimum correction amount MC1 in the first direction (α direction), a minimum correction amount MC2 in the second direction (β direction), and a minimum correction amount MC3 in the rotational direction (θ direction).

[0087] FIG. 8 shows another example of the settings screen. By operating the operation area BP51, the user can set the preliminary threshold value TH4, the preliminary threshold value TH6, the number of pads, the number of boards, and the corrective action. For example, the settings at the top of FIG. 8 indicate that the corrective action indicated by Action 1 will be executed when the number of pads PD1 and the number of boards BD1 consecutively reach a state in which the area of ​​the solder 80 printed on the board 90 exceeds a percentage S1 (%) of the target area SG0. The percentage S1 corresponds to the preliminary threshold value TH6, and in this case, the percentage S1 is set to be smaller than the upper limit (percentage) of the inspection threshold for the area of ​​the solder 80 printed on the board 90.

[0088] The setting in the second row from the top indicates that when a state occurs in which the area of ​​solder 80 printed on board 90 falls below percentage S2 (%) of target area SG0 for a consecutive number of pads PD2 and number of boards BD2, a corrective action shown as Process 2 is executed. Percentage S2 corresponds to preliminary threshold TH4, and in this case, percentage S2 is set to be greater than the lower limit (percentage) of the inspection threshold for the area of ​​solder 80 printed on board 90.

[0089] The settings in the third and fourth rows from the top are conditions and process settings for the volume of solder 80 printed on the board 90, and are set in the same way as the area of ​​the solder 80 printed on the board 90. The user can input any number of pads and boards. Processes (countermeasures) that can be input in Process 1 to Process 4 include, for example, the type of cleaning of the mask 70, abnormal stopping of the printer WM1, and replenishing of solder 80.

[0090] 9 shows another example of the setting screen. This figure shows an example of the setting screen on the display device of the print inspection machine WM2. By operating the operation area BP51, the user can set a first threshold TH1 for determining misalignment of the solder 80, a threshold TH3 for determining smearing of the solder 80, a threshold TH5 for determining bleed or bridging of the solder 80, and so on.

[0091] 2.Printing quality control method What has already been said about print quality control system 50 also applies to the print quality control method. Specifically, the print quality control method comprises an acquisition step and a correction step. The acquisition step corresponds to the control performed by acquisition unit 51. The correction step corresponds to the control performed by correction unit 52. The print quality control method can also comprise a pre-processing step. The pre-processing step corresponds to the control performed by pre-processing unit 53. The print quality control method can also comprise a setting step. The setting step corresponds to the control performed by setting unit 54.

[0092] 3. Examples of Effects of the Embodiments According to the print quality control system 50, the relative positions of the mask 70 and the substrate 90 can be corrected for each printing direction (Y direction) before the deviation PD0 of the solder 80 printed on the substrate 90 from the target printing position PG0 reaches the threshold value used to determine the positional misalignment of the solder 80. What has been described above about the print quality control system 50 also applies to the print quality control method. [Explanation of symbols]

[0093] 34: Squeegee, 50: Print quality control system, 51: Acquisition unit, 52: Correction unit, 53: Pre-processing unit, 54: Setting unit, 70: Mask, 71: Opening, 90: Substrate, PG0: Target printing position, PD0: Deviation, TH1: First threshold, TH2: Second threshold, MC0: Minimum correction amount, SG0: target area, SH0: area, SR0: tolerance, TH3: threshold, TH4: preliminary threshold, TH5: threshold, TH6: preliminary threshold, WM1: Printing machine, Y direction: Printing direction, Y1 direction: Forward direction, Y2 direction: Return direction, α direction: First direction, β direction: Second direction, θ direction: rotation direction.

Claims

1. an acquisition unit that acquires, for each printing direction, a deviation of the solder printed on the board through the openings in the mask by sliding the squeegee over the mask from a target printing position; a correction unit that corrects the relative positions of the mask and the board for each printing direction so as to reduce the deviation when the deviation acquired by the acquisition unit exceeds a second threshold that is set smaller than a first threshold for determining misalignment of the solder; and A print quality control system comprising:

2. The print quality control system according to claim 1 , wherein the acquisition unit acquires the deviation for a predetermined number of the substrates for each of the printing directions, and sets an average value of the acquired deviations as the deviation for each of the printing directions.

3. 3. The print quality control system according to claim 1, wherein the printing direction comprises an outward direction in which the squeegee slides over the mask in one direction, and a return direction in which the squeegee slides over the mask in the opposite direction to the outward direction.

4. 2. The printing quality control system of claim 1, wherein the correction unit corrects at least one of the deviation in a first direction that is a direction along the printing direction, the deviation in a second direction that is a direction perpendicular to the first direction in a horizontal plane, and the deviation in a rotational direction of one of the mask and the substrate relative to the other.

5. The print quality control system according to claim 1 , wherein the correction unit gradually corrects the relative position between the mask and the substrate by an amount of correction that is smaller than the deviation acquired by the acquisition unit.

6. 2. The printing quality control system according to claim 1, wherein the correction unit corrects the relative position of the mask and the substrate when the deviation acquired by the acquisition unit is greater than the minimum correction amount by which the relative position of the mask and the substrate can be corrected.

7. the acquisition unit acquires an area of ​​the solder printed on the board, The printing quality control system according to claim 1 , wherein the correction unit corrects the relative position of the mask and the board when the area of ​​the solder acquired by the acquisition unit is within an allowable range set based on a target area.

8. the acquisition unit acquires an area of ​​the solder printed on the board, The print quality control system according to claim 1, further comprising a pre-processing unit that executes in advance the countermeasures to be taken when the solder fades when the area of ​​the solder acquired by the acquisition unit is not within an acceptable range set based on a target area and the area is smaller than a preliminary threshold set larger than the threshold for determining the solder fade.

9. The print quality control system according to claim 8 , wherein the pre-processing unit performs wet cleaning of the mask as the corrective action.

10. the acquisition unit acquires an area of ​​the solder printed on the board, The print quality control system according to claim 1, further comprising a pre-processing unit that executes in advance the countermeasures to be taken when the solder bleeds or the bridging occurs when the area of ​​the solder acquired by the acquisition unit is not within an acceptable range set based on a target area and the area is larger than a preliminary threshold set smaller than the threshold for determining the solder bleeds or the bridging.

11. The print quality control system according to claim 10 , wherein the pre-processing unit performs dry cleaning of the mask as the corrective action.

12. The print quality control system according to claim 1 , further comprising a setting unit that allows a user of a printing machine that prints the solder on the board to set a predetermined threshold value including at least one of the first threshold value and the second threshold value.

13. an acquiring step of acquiring deviations of solder printed on a board from a target printing position for each printing direction by sliding a squeegee over the mask through openings in the mask; a correction step of correcting the relative positions of the mask and the board for each printing direction so as to reduce the deviation when the deviation acquired by the acquisition step exceeds a second threshold set smaller than a first threshold for determining the positional misalignment of the solder; A print quality control method comprising:

Images