JP7539082B2 - Printing device and printing method - Google Patents

Description

This disclosure relates to a printing device and a printing method.

Conventionally, a substrate screen printing device is known as a printing device that maintains the viscosity of cream solder at a suitable level for printing after a long period of interruption in printing (see Patent Document 1).

JP 2008-307864 A

The technology in Patent Document 1 makes it possible to adjust the viscosity of the solder, but it is anticipated that it may be difficult to adjust the solder viscosity to an appropriate viscosity for printing, and it is desirable to plan printing based on the changed viscosity.

This disclosure provides a printing device and printing method that can suppress printing defects caused by changes in the viscosity of the solder without adjusting the viscosity of the solder.

One aspect of the present disclosure is a printing apparatus that uses a squeegee that slides over a mask to print solder paste on a substrate through an opening in the mask, the printing apparatus comprising: a viscometer that measures the viscosity of the solder paste placed on the mask; a processor that determines printing conditions for printing the solder paste with the squeegee based on the viscosity of the solder paste measured by the viscometer; a communication device that acquires a volume ratio indicating a filling amount of the solder paste relative to the size of the opening in the mask from a solder printing inspection device that inspects the printing state of the solder paste; and a memory. The processor accumulates in the memory actual information on the viscosity measured multiple times in the past by the viscometer, actual information on the printing conditions determined multiple times in the past, and actual information on the volume ratio obtained multiple times in the past from the solder print inspection device corresponding to the actual information on the viscosity and the actual information on the printing conditions, generates correlation information indicating a correlation between the viscosity, the printing conditions, and the volume ratio based on the actual information on the viscosity, the actual information on the printing conditions, and the actual information on the volume ratio, and determines the printing conditions based on the viscosity measured by the viscometer and the correlation information .

One aspect of the present disclosure is a printing method for printing solder paste on a substrate through an opening in a mask using a squeegee that slides over the mask, the method comprising the steps of: measuring the viscosity of the solder paste placed on the mask; determining printing conditions for printing the solder paste with the squeegee based on the measured viscosity of the solder paste; acquiring a volume ratio indicating a filling amount of the solder paste relative to the size of the opening in the mask from a solder printing inspection device that inspects the printing state of the solder paste; and measuring the volume ratio of the solder paste that has been filled multiple times in the past using a viscometer. the step of storing in a memory the actual viscosity information that has been determined, the actual printing condition information that has been determined multiple times in the past, and the actual volume ratio information that has been obtained multiple times in the past from the solder print inspection device corresponding to the actual viscosity information and the actual printing condition information; the step of generating correlation information that indicates a correlation between the viscosity, the printing conditions, and the volume ratio based on the actual viscosity information, the actual printing condition information, and the actual volume ratio information; and the step of determining the printing conditions based on the viscosity measured by the viscometer and the correlation information .

According to the present disclosure, it is possible to suppress printing defects caused by changes in the viscosity of the solder without adjusting the viscosity of the solder.

FIG. 1 is a block diagram illustrating an example of the configuration of a printing system according to an embodiment of the present disclosure. FIG. 1 is a perspective view of a screen printing apparatus according to an embodiment of the present disclosure. FIG. 1 is a side view of a screen printing apparatus according to an embodiment of the present disclosure. FIG. 1 is a partial perspective view of a screen printing apparatus according to an embodiment of the present disclosure. FIG. 1 is a partial plan view of a screen printing apparatus according to an embodiment of the present disclosure; FIG. 2 is a block diagram showing an example of a control system of the screen printing apparatus according to the embodiment of the present disclosure. A flowchart showing an example of an operation of a screen printing device according to an embodiment of the present disclosure. FIG. 1 is a diagram illustrating an example of a relative relationship between a squeegee angle and a volume ratio according to an embodiment of the present disclosure. FIG. 1 is a diagram showing an example of a relative relationship between a squeegee printing pressure and a volume ratio according to an embodiment of the present disclosure.

Below, the embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanations than necessary may be omitted. For example, detailed explanations of already well-known matters or duplicate explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the attached drawings and the following explanation are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(How one embodiment of the present disclosure was achieved)
Printing devices may stop printing for several tens of minutes due to shift changes, running out of materials, lunch time, etc. In this case, the solder is left on the mask, hardens, and its viscosity increases. If the next printing is performed in this state, the amount of solder filled into the mask openings will be too small because the solder is hard. In the past, to avoid such a situation, the time interval between printings was managed, and when printing was stopped for a long time, the equipment was stopped and the operator was prompted to perform a dummy print, or a round trip print was performed. However, the former requires manual action by the operator, and the latter can result in too much solder being used for printing.

In addition, while the technology in Patent Document 1 makes it possible to adjust the viscosity of the solder, it is anticipated that there will be situations in which it will be difficult to adjust the viscosity of the solder to an appropriate viscosity for printing, and it is also desirable to plan printing based on the changed viscosity. For example, a printing device that includes a device for adjusting the viscosity of the solder will be required, but it is anticipated that preparing such a printing device will be difficult. In addition, time will be required to adjust the viscosity, and it is anticipated that it will be difficult to secure printing time that includes the time required for viscosity adjustment.

In the following embodiment, we describe a printing device and printing method that can suppress printing defects caused by changes in the viscosity of solder without adjusting the viscosity of the solder.

(One embodiment)
(Printing system configuration)
1 is a block diagram showing an example of the configuration of a printing system 5 according to an embodiment of the present disclosure. The printing system 5 includes a printing device 100, a management computer 200, and a solder print inspection device 300. The printing system 5 may include other devices or facilities for printing on a substrate (e.g., a board).

The printing device 100 prints solder paste on a non-printed object (e.g., a circuit board). The management computer 200 is, for example, an LNB (Line Network Box) that is a higher-level device, and manages various devices (e.g., the solder print inspection device 300) or various pieces of equipment included in the printing system 5. The management computer 200 can operate, for example, as an MES (Manufacturing Execution System), and can visualize and manage the manufacturing process, and instruct or assist workers. In addition, under the management of the management computer 200, the printing device 100 can communicate various data or information with various other devices or pieces of equipment.

The solder printing inspection device 300 is an SPI (Solder Paste Inspection) device that inspects the printing condition of a non-printed object on which solder paste has been printed by the printing device 100. This printing condition includes, for example, the volume ratio, height, area, positional deviation, etc. of the solder paste printed in the printing area of the printing object. This volume ratio as the printing condition indicates the amount of solder paste filled relative to the size of the printing area.

The printing device 100, the management computer 200, and the solder print inspection device 300 are connected by various communication networks. This communication network may be, for example, a LAN (Local Area Network) or other communication networks.

(Printing device configuration)
Fig. 2 is a perspective view of the printing device 100 according to an embodiment of the present disclosure. Fig. 3 is a side view of the printing device 100 according to an embodiment of the present disclosure. Fig. 4 is a partial perspective view of the printing device 100 according to an embodiment of the present disclosure. Fig. 5 is a partial plan view of the printing device 100 according to an embodiment of the present disclosure.

The printing device 100 receives a board 2 (e.g., a circuit board) input from the upstream process side, screen-prints a paste Pst such as solder on each electrode 2d of the board 2, and repeatedly executes a screen printing operation to pass the board 2 to a downstream process device (e.g., a component mounting device or a solder print inspection device 300, not shown). For ease of explanation, the left-right direction as seen by the worker is defined as the X-axis direction, the left is the upstream process side, and the right is the downstream process side. In addition, the front-to-back direction, with the worker OP as the front and the direction away from the worker OP as the rear, is defined as the Y-axis direction, and the up-down direction is defined as the Z-axis direction.

In Figures 2 and 3, the printing device 100 has a substrate holding and moving mechanism 12 on a base 11, and a screen mask 13 (an example of a mask) is provided above the substrate holding and moving mechanism 12.

As shown in Figures 4 and 5, to the left of the substrate holding and moving mechanism 12 is an input conveyor 14 that receives the substrate 2 input from the upstream process side of the printing device 100 and transports it to the substrate holding and moving mechanism 12. Also, to the right of the substrate holding and moving mechanism 12 is an output conveyor 15 that receives the substrate 2 from the substrate holding and moving mechanism 12 and transports it to the downstream process side. A camera 16 is movably provided in the area below the screen mask 13, and a squeegee head 17 is movably provided in the area above the screen mask 13.

3 and 4, the substrate holding and moving mechanism 12 is composed of a substrate holding section 21 and a moving table section 22 (one example of a table). The substrate holding section 21 is equipped with a positioning conveyor 31 (see FIG. 5), a lower support section 32, and a pair of front and rear clampers 33 (see FIG. 5). The positioning conveyor 31 positions the substrate 2 received from the carry-in conveyor 14 at a predetermined clamping position. The lower support section 32 supports the substrate 2 positioned at the clamping position by the positioning conveyor 31 from below. The clamper 33 clamps and holds the substrate 2 from the side (Y-axis direction). Of the two clampers 33 possessed by the substrate holding section 21, the one located on the side of the worker OP is called the front clamper 33F, and the one located on the opposite side to the worker OP is called the rear clamper 33R. The moving table section 22 is composed of an XYθ table mechanism consisting of multiple table mechanisms stacked in multiple stages, and moves the substrate holding section 21 in the horizontal plane and up and down directions.

In Figures 2 and 3, the screen mask 13 is made of a rectangular metal plate extending in the XY plane. In Figure 5, the central rectangular area of the screen mask 13 is the substrate contact area R, whose underside contacts the substrate 2. Pattern openings 13h are provided in the substrate contact area R in correspondence with the arrangement of the electrodes 2d of the substrate 2. The outer periphery of the screen mask 13 is supported by a frame member 13W.

In FIG. 3, the camera 16 has an upper imaging section 16a whose imaging field of view faces upward, and a lower imaging section 16b whose imaging field of view faces downward. The camera 16 is driven by a camera movement mechanism 16K (see FIG. 2) that uses a ball screw mechanism as an actuator to move within the XY plane.

2 and 3, the squeegee head 17 includes a moving base 41, two squeegees 42, and two squeegee lifting cylinders 43. The moving base 41 is a member extending in the X-axis direction, and is driven by a squeegee head moving mechanism 17K with a ball screw mechanism as an actuator to move in the Y-axis direction. The two squeegees 42 are arranged facing each other in a front-to-back arrangement on the moving base 41, and move back and forth in the Y-axis direction as a unit by the movement of the moving base 41 in the Y-axis direction. Of the two front and rear squeegees 42, the one located in the front (right side of the paper in FIG. 3) is called the front squeegee 42F, and the one located in the rear (left side of the paper in FIG. 3) is called the rear squeegee 42R. The two squeegees 42 are each made of a spatula-shaped member extending in the X-axis direction, and extend diagonally downward with each other spreading out downward. The rear surface of the front squeegee 42F is the paste scraping surface, and the front surface of the rear squeegee 42R is the paste scraping surface.

The two squeegee lifting cylinders 43 are arranged side by side in the front-to-rear direction on the moving base 41 corresponding to the two squeegees 42. The two squeegee lifting cylinders 43 operate individually to raise and lower the two squeegees 42 independently relative to the moving base 41. Each squeegee lifting cylinder 43 can raise and lower the corresponding squeegee 42 between a standby height position (see squeegee 42 shown in Figure 3) where the lower end of the squeegee 42 is spaced a predetermined distance from the upper surface of the screen mask 13, and a contact height position where the lower end abuts against the screen mask 13.

The squeegee head 17 also includes a viscometer lifting cylinder 46 and a viscometer 47. The viscometer lifting cylinder 46 is provided above the moving base 41 in correspondence with the viscometer 47. The viscometer lifting cylinder 46 lifts and lowers the viscometer 47 relative to the moving base 41. The viscometer lifting cylinder 46 can lift and lower the viscometer 47 between a standby height position (see the viscometer 47 shown in FIG. 3) where the lower end of the viscometer 47 is spaced a predetermined distance from the upper surface of the screen mask 13, and a contact height position where the lower end of the viscometer 47 contacts the screen mask 13. The viscometer lifting cylinder 46 brings the viscometer 47 into contact with the paste Pst placed on the screen mask 13. The viscometer 47 measures the viscosity of the contacted paste Pst.

Figure 6 is a block diagram showing a control system of the printing device 100 in one embodiment of the present disclosure. The printing device 100 includes a control device 60, an input device 61, a servo driver 81, a servo motor 83, an electropneumatic regulator 85, a viscometer controller 87, a communication device 91, and a memory 93.

The control device 60 is configured with a processor. The processor includes, for example, an MPU (Micro Processing Unit), a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). The control device 60 performs various processes or controls by executing programs stored in the memory 93. The memory 93 includes, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory). The memory 93 may include a HDD (Hard Disk Drive) or a SSD (Solid State Drive), etc. The memory 93 may include an optical disk or an SD card, etc. The memory 93 stores, for example, various data, various information, or various programs.

For example, the control device 60 controls the transport operation of the substrate 2 by the carry-in conveyor 14, the holding and moving operation of the substrate 2 by the substrate holding and moving mechanism 12, and the transport operation of the substrate 2 by the carry-out conveyor 15. For example, the control device 60 controls the movement operation of the camera 16 by the camera moving mechanism 16K, the image capturing operation of the camera 16, the movement operation of the squeegee head 17 by the squeegee head moving mechanism 17K, and the lifting and lowering operation of each squeegee 42 by the squeegee lifting cylinder 43. In addition, image data obtained by imaging with the camera 16 is sent to the control device 60, and the image processing unit 60a of the control device 60 performs image recognition on the image data.

In the printing device 100, necessary input is made from an input device 61 connected to the control device 60. For example, the control device 60 can arbitrarily set the contact points of each of the pair of front and rear squeegees 42 by input from the input device 61.

The control device 60 controls the lifting and lowering operation of the viscometer 47 by the viscometer lifting cylinder 46. The control device 60 controls the viscometer controller 87. The viscometer controller 87 controls the viscosity measurement operation by the viscometer 47. The viscosity measurement data by the viscometer 47 is sent to the control device 60. The viscometer 47 may measure the viscosity of the paste Pst according to the control of the control device 60, for example, at the start of production when the printing device 100 is started, or when printing is resumed if the unprinted time described below is equal to or longer than a predetermined time. The control device 60 may use each viscosity measurement data for calculations by the control device 60, or may store it in the memory 93 as viscosity performance information.

The control device 60 controls the driving of the servo driver 81. The servo driver 81 controls the operation of the servo motor 83 and instructs the servo motor 83 to rotate. The servo motor 83 rotates according to the rotation instruction from the servo driver 81 to control the squeegee angle of the squeegee 42 and shift (change) the squeegee angle. The squeegee angle is the angle of the squeegee 42 with respect to the screen mask 13 when the squeegee 42 slides on the screen mask 13, and is also called the attack angle or squeegee attack angle. The control device 60 may store the changed squeegee angle in the memory 93 as squeegee angle performance information each time the squeegee angle is changed.

The control device 60 controls the electro-pneumatic regulator 85. The electro-pneumatic regulator 85 controls the squeegee printing pressure by controlling the air pressure in proportion to the electrical signal input to the electro-pneumatic regulator 85, thereby controlling the squeegee printing pressure and transitioning the squeegee printing pressure. The squeegee printing pressure is the pressure with which the squeegee 42 presses against the screen mask 13 when the squeegee 42 slides over the screen mask 13. The control device 60 may store the changed squeegee printing pressure in the memory 93 as actual squeegee printing pressure information each time the squeegee printing pressure is changed.

The control device 60 controls communication by the communication device 91. The control device 60 may send data transmitted by the communication device 91 to the communication device 91. The control device 60 may obtain data received by the communication device 91.

The communication device 91 communicates with an external device (e.g., the management computer 200 or the solder print inspection device 300) via, for example, a communication network. For example, the communication device 91 acquires information on the printing state from the solder print inspection device 300. The printing state information includes, for example, information on the volume ratio. For example, the communication device 91 may acquire the volume ratio each time the solder print inspection device 300 inspects the printing state of the paste Pst on the substrate 2 as the printing substrate. The control device 60 may store the acquired volume ratio in the memory 93 as actual volume ratio information each time the volume ratio is acquired from the solder print inspection device 300.

The control device 60 determines the printing conditions for printing the paste Pst with the squeegee 42 based on the information stored in the memory 93. The printing conditions may include, for example, the squeegee angle, the squeegee printing pressure, or the sliding speed. The sliding speed is the speed at which the squeegee 42 slides over the screen mask 13. The control device 60 may determine the printing conditions based on the viscosity of the paste Pst measured by the viscometer 47. Note that the sliding speed may be preset to a constant speed regardless of the viscosity of the paste Pst.

The control device 60 measures time. For example, the control device 60 measures time related to the printing operation by the printing device 100. The printing operation is an operation in which the squeegee 42 slides on the screen mask 13 and the paste Pst is printed on the substrate 2 through the pattern openings 13h provided in the screen mask 13. The printing operation can be interrupted during printing and can be resumed after interruption. Interruption during printing may be instructed, for example, by input from the input device 61, or may be performed when the current time measured by the control device 60 reaches a predetermined time. The control device 60 may measure the start time and end time of the printing operation. The control device 60 may measure the interruption time when the printing operation is interrupted and the restart time when the printing operation is restarted after the interruption. The control device 60 may calculate the time between the interruption time when the printing operation is interrupted and the restart time when the printing operation is restarted after the interruption as the unprinted time.

(Operation of the Printing Device)
7 is a flowchart showing an example of the operation of the printing apparatus 100 according to an embodiment of the present disclosure. In FIG. 7, the printing condition to be adjusted is the squeegee angle.

The control device 60 starts the printing device 100 and starts the production of electronic components using the substrate 2 (S11). Before the start of the production of electronic components or after S11, the paste Pst is placed on the screen mask 13. The control device 60 controls the viscometer lifting cylinder 46 to lower the viscometer 47, and the viscometer 47 contacts the paste Pst placed on the screen mask 13 to measure the viscosity of the paste Pst (S12). After measuring the viscosity of the paste Pst, the control device 60 controls the viscometer lifting cylinder 46 to raise the viscometer 47. The control device 60 acquires the viscosity measurement data from the viscometer 47 and stores the measurement data in the memory 93. For example, information that the viscosity is 200 Pa·s is written to the memory 93 as the measurement data. Also, at this point, for example, the squeegee angle is set to 60 degrees, and information that the squeegee angle is 60 degrees is written to the memory 93. The control device 60 starts the printing operation by the printing device 100 (S13).

The control device 60 determines whether or not printing has been performed for T1 minutes (e.g., 30 minutes) or more during processing of S14 (S14). That is, the control device 60 determines whether or not the unprinted time is T1 minutes or more during processing of S14. The 30 minutes exemplified as T1 is the time over which the viscosity is expected to change if left on the screen mask 13, but T1 may be another time. If the unprinted time is less than T1 minutes, proceed to S14.

If the unprinted time is T1 minutes or more, the control device 60 controls the viscometer lifting cylinder 46 to lower the viscometer 47, and the viscometer 47 contacts the paste Pst placed on the screen mask 13 to measure the viscosity of the paste Pst (S15). After measuring the viscosity of the paste Pst, the control device 60 controls the viscometer lifting cylinder 46 to raise the viscometer 47. The control device 60 acquires the viscosity measurement data from the viscometer 47 and stores the measurement data in the memory 93. For example, information that the viscosity is 220 Pa·s is written to the memory 93 as the measurement data. Also, at this point, for example, the squeegee angle is set to 60 degrees, and information that the squeegee angle is 60 degrees is written to the memory 93. In other words, at the time of processing in S15, it can be said that the viscosity of the paste Pst has increased due to the long time the paste Pst has been left.

The control device 60 calculates the difference between the viscosity measured this time in S15 and the viscosity measured previously and stored in the memory 93. The control device 60 then determines whether this difference is equal to or greater than T2 (Pa·s) (e.g., ±10 Pa·s). In other words, the control device 60 determines whether the viscosity has changed by T2 (Pa·s) or more between the previous measurement and the current measurement (S16). For example, if the viscosity measured last time and the viscosity measured this time are both 200 Pa·s, S16 will be No, and if the viscosity measured last time was 200 Pa·s and the viscosity measured this time is 220 Pa·s, S16 will be Yes.

If the viscosity has not changed by T2 or more in S16, the control device 60 proceeds to S14. In other words, since the viscosity of the paste Pst has not changed significantly in the printing device 100, the frequency of print defects is low even if printing is continued without changing the squeegee angle as a printing condition.

If the viscosity has changed by T2 or more in S16, the control device 60 changes the printing conditions using the squeegee 42. Here, the control device 60 changes the squeegee angle as a printing condition based on the viscosity measured in S15 (S17). In this case, the control device 60 may, for example, change the squeegee angle (e.g., decrease it) by a predetermined angle, or may change the squeegee angle based on relative information regarding the squeegee angle, which will be described later. The control device 60 obtains information on the changed printing conditions and stores the information on the changed printing conditions in the memory 93. For example, information that the changed squeegee angle is 55 degrees is written to the memory 93.

For example, when the angle of the squeegee 42 relative to the screen mask 13 is changed to be smaller, the force with which the squeegee 42 presses the paste Pst into the screen mask 13 increases, and the force with which the paste Pst is filled increases. Therefore, even if the viscosity of the paste Pst increases, the printing device 100 can prevent an insufficient amount of paste Pst from being filled in the area to be printed.

The control device 60 acquires inspection data on the printing state of the paste Pst printed on the substrate 2 from the solder print inspection device 300 via the communication device 91. The control device 60 acquires volume ratio information contained in the inspection data. The control device 60 determines whether the acquired volume ratio is a value within the range of T3 (%) (e.g., 100±10%) (S18).

If the acquired volume ratio is within the range of T3, the control device 60 proceeds to S14. In other words, if the paste Pst is filled exactly with respect to the size of the electrode 2d of the substrate 2, which is the printing area where the paste Pst is printed, the control device 60 can determine that no further changes to the printing conditions are necessary.

If the acquired volume ratio is not within the range of T3, the control device 60 proceeds to S17. In other words, the control device 60 can determine that the amount of paste Pst filled is too much or too little relative to the size of the electrode 2d on the substrate 2, which is the printing area, and therefore further changes to the printing conditions are necessary, and can change the printing conditions again.

According to the operation of the printing device 100, the viscosity of the paste Pst is measured at the start of production, and if the unprinted time is equal to or longer than a predetermined time (e.g., 30 minutes), the viscosity is measured again. Then, when the paste Pst has hardened to a degree that satisfies a predetermined standard, the printing device 100 can change the printing conditions, such as the squeegee angle, and continue printing.

The control device 60 of the printing device 100 may also adjust the printing conditions based on the volume ratio. Specifically, the control device 60 may repeatedly change the printing conditions, such as the squeegee angle, so that the printing state is in a predetermined state, for example, so that the volume ratio falls within a predetermined range. In other words, the control device 60 may repeatedly perform the processes of S17 and S18. Thus, the printing device 100 receives feedback on the state of the printing result corresponding to the printing conditions, and can make the printing state of the paste Pst in a desired state even if the viscosity of the paste Pst changes. Thus, the printing device 100 can be sure that the printing state has been improved by changing the printing conditions, for example, that the filling amount of the paste Pst has been increased by reducing the squeegee angle.

Note that confirmation of the volume ratio in S18 may be omitted. In this case, the printing device 100 can quickly determine printing conditions such as the squeegee angle.

Note that while FIG. 7 illustrates an example in which the printing condition to be adjusted is the squeegee angle, other printing conditions may be adjusted. For example, the squeegee printing pressure may be adjusted instead of or in addition to the squeegee angle.

Figure 8 shows an example of the relative relationship between the squeegee angle and the volume ratio in one embodiment of the present disclosure.

In FIG. 8, the horizontal axis shows the squeegee angle (degrees) as the squeegee angle, and the vertical axis shows the volume fraction (%), and the relative relationship between the squeegee angle and the volume fraction is shown for each viscosity of the paste Pst. In FIG. 8, the relative relationship between the squeegee angle and the volume fraction is a linear relationship as an example, and is shown by a straight line. Note that this relative relationship may not be a linear relationship, but may be a nonlinear relationship. Relative information indicating the relative relationship between the squeegee angle and the volume fraction is stored in the memory 93. This relative information may be stored in the memory 93 in advance, may be obtained from an external device via the communication device 91 and stored in the memory 93, or may be derived by calculation by the control device 60 and stored in the memory 93.

In the correlation information between the squeegee angle and the volume ratio, for example, as shown in the linear relationship in FIG. 8, the higher the viscosity, the smaller the squeegee angle, and the lower the viscosity, the larger the squeegee angle. Therefore, based on the correlation information, the control device 60 reduces the squeegee angle the higher the viscosity measured by the viscometer 47, and increases the squeegee angle the lower the viscosity measured by the viscometer 47.

When the control device 60 derives the relative information by calculation, the relative information may be generated based on past measurement or inspection results information. For example, the results information of the viscosity of the paste Pst, the results information of the squeegee angle, and the results information of the volume ratio obtained in the case of the results information of the viscosity and the squeegee angle may be stored in the memory 93 after the past viscosity measurement, the setting of the squeegee angle, or the acquisition of the volume ratio. The control device 60 acquires information of each results point corresponding to each position indicated by the black circle "●" mark in FIG. 8 (each results information of the viscosity, each results information of the squeegee angle, and each results information of the volume ratio) from the memory 93, etc. In this case, the control device 60 may generate the relative information based on each results information of the viscosity, each results information of the squeegee angle, and each results information of the volume ratio. In FIG. 8, the squeegee angle and the volume ratio are linearly approximated for each viscosity by connecting each results point.

The relative information is used to determine the squeegee angle. For example, in S17 of FIG. 7, the control device 60 may determine a squeegee angle suitable for the viscosity of the paste Pst based on the viscosity of the paste Pst measured by the viscometer 47 and the relative information stored in the memory 93. Assume that the viscosity obtained in S12 of FIG. 7 is 200 Pa·s, and the viscosity obtained in S15 is 220 Pa·s. In this case, in S17 of FIG. 7, the control device 60 determines the squeegee angle so that the volume fraction of the paste Pst with a viscosity of 220 Pa·s is 100%. In other words, the control device 60 determines the squeegee angle to be 50 degrees, and controls the servo driver 81 and the servo motor 83 so that the squeegee angle is 50 degrees. As a result, the squeegee angle is adjusted to 50 degrees. In this way, the control device 60 determines the squeegee angle so that the volume fraction is 100% in accordance with the viscosity.

In addition, each time screen printing is performed, the number of pieces of performance information that are accumulated increases. The control device 60 may regenerate the relative information at a predetermined timing based on each piece of performance information. This allows the printing device 100 to obtain relative information that is more in line with the actual situation, and to set a squeegee angle that is more suitable for screen printing. For example, a large number of performance points can be mapped on a two-dimensional plane defined by the squeegee angle and volume ratio in Figure 8, and relative information can be generated by nonlinearly approximating the performance points.

The control device 60 may also generate relative information through machine learning. For example, the control device 60 may experimentally determine various squeegee angles for various viscosities and obtain the volume ratio for these viscosities and squeegee printing pressures. The control device 60 may then use machine learning to generate a trained model of what squeegee angle is preferable for a given viscosity (e.g., whether the volume ratio is 100%). This trained model is a model for determining the squeegee angle from the viscosity of the paste Pst. The control device 60 may use this trained model as relative information.

For example, when the viscosity of the paste Pst is 200 Pa·s, the control device 60 may learn whether the squeegee angle should be set to 60 degrees or 55 degrees in order to bring the volume fraction closer to 100%, and generate a trained model. In other words, the trained model may be generated by acquiring and learning a large amount of data on the viscosity, squeegee angle, and volume fraction as training data. The training data may be past performance information on the viscosity, squeegee angle, and volume fraction. The control device 60 can determine the squeegee angle based on the viscosity measured by the viscometer 47 according to the trained model as relative information.

The control device 60 may also generate a trained model by learning whether it is better to make the squeegee angle 5 degrees or 10 degrees smaller than the current squeegee angle in order to bring the volume fraction closer to 100% when the viscosity of the paste Pst has hardened by 20 Pa·s more than the viscosity at the time the current squeegee angle was determined. In other words, the trained model may be generated by acquiring and learning a large amount of data on the amount of change in viscosity, the amount of change in squeegee angle, and the volume fraction as training data. The control device 60 can determine the squeegee angle based on the viscosity measured by the viscometer 47 according to the trained model as relative information.

The filling force of the paste Pst changes depending on the squeegee angle, so the squeegee angle affects the printing condition. In contrast, the printing device 100 determines the squeegee angle based on the relative information between the viscosity of the paste Pst, the squeegee angle, and the volume ratio, so it can determine a squeegee angle suitable for the viscosity, set the volume ratio to the desired state, and maintain a good printing condition. In addition, the printing device 100 can evaluate the optimal squeegee angle according to the viscosity of the paste Pst and derive the relative information with high accuracy. Since the squeegee angle determined based on this relative information is highly reliable, there is a low possibility that the printing condition will be poor and the volume ratio will be outside the acceptable range. In this case, the printing device 100 can suppress a decrease in printing accuracy even if the determination of the volume ratio is omitted in S18 of FIG. 7.

Figure 9 shows an example of the relative relationship between squeegee printing pressure and volume ratio in one embodiment of the present disclosure.

9, the horizontal axis shows the squeegee pressure (N) and the vertical axis shows the volume fraction (%), and the relative relationship between the squeegee pressure and the volume fraction is shown for each viscosity of the paste Pst. In FIG. 9, the relative relationship between the squeegee pressure and the volume fraction is a linear relationship as an example, and is shown by a straight line. Note that this relative relationship may not be a linear relationship, but may be a nonlinear relationship. Relative information indicating the relative relationship between the squeegee pressure and the volume fraction is stored in the memory 93. This relative information may be stored in the memory 93 in advance, may be obtained from an external device via the communication device 91 and stored in the memory 93, or may be derived by calculation by the control device 60 and stored in the memory 93.

In the correlation information between the squeegee printing pressure and the volume ratio, for example, as shown in the linear relationship in FIG. 9, the higher the viscosity, the lower the squeegee printing pressure, and the lower the viscosity, the higher the squeegee printing pressure. Therefore, based on the correlation information, the control device 60 reduces the squeegee printing pressure the higher the viscosity measured by the viscometer 47, and increases the squeegee printing pressure the lower the viscosity measured by the viscometer 47.

When the control device 60 derives the relative information by calculation, the relative information may be generated based on past measurement or inspection results information. For example, the results information of the viscosity of the paste Pst, the results information of the squeegee printing pressure, and the results information of the volume ratio obtained in the case of the results information of the viscosity and the squeegee printing pressure may be stored in the memory 93 after the past viscosity measurement, the setting of the squeegee printing pressure, or the acquisition of the volume ratio. The control device 60 acquires information of each results point corresponding to each position indicated by the black circle "●" in FIG. 9 (each results information of the viscosity, each results information of the squeegee printing pressure, and each results information of the volume ratio) from the memory 93 or the like. In this case, the control device 60 may generate the relative information based on each results information of the viscosity, each results information of the squeegee printing pressure, and each results information of the volume ratio. In FIG. 9, the squeegee printing pressure and the volume ratio are linearly approximated for each viscosity by connecting each results point.

The relative information is used to determine the squeegee printing pressure. For example, the operation example of FIG. 7 is applied to the case where the squeegee angle is determined as a printing condition, and the squeegee printing pressure is changed in the process corresponding to S17. In the process corresponding to S17 of FIG. 7, the control device 60 determines a squeegee printing pressure suitable for the viscosity of the paste Pst based on the viscosity of the paste Pst measured by the viscometer 47 and the relative information stored in the memory 93. Suppose that the viscosity obtained in S12 of FIG. 7 is 200 Pa·s and the viscosity obtained in S15 is 220 Pa·s. In this case, in the process corresponding to S17 of FIG. 7, the control device 60 determines the squeegee printing pressure so that the volume ratio of the paste Pst with a viscosity of 220 Pa·s is 100%. In other words, in the case of the relative information of the linear relationship shown in FIG. 9, the control device 60 determines the squeegee printing pressure to be 80 N, and controls the electropneumatic regulator 85 so that the squeegee printing pressure is 80 N. As a result, the squeegee printing pressure is adjusted to 80 N. In this way, the control device 60 determines the squeegee pressure that corresponds to the viscosity and results in a volume ratio of 100%.

In addition, each time screen printing is performed, the number of pieces of performance information that are accumulated increases. The control device 60 may regenerate the relative information at a predetermined timing based on each piece of performance information. This allows the printing device 100 to obtain relative information that is more in line with the actual situation, and to set a squeegee pressure that is more suitable for screen printing. For example, a large number of performance points can be mapped on a two-dimensional plane defined by the squeegee pressure and volume ratio in FIG. 9, and relative information can be generated by nonlinearly approximating the performance points.

The control device 60 may also generate the relative information through machine learning. For example, the control device 60 may experimentally determine various squeegee printing pressures for various viscosities and obtain the volume ratio for these viscosities and squeegee printing pressures. The control device 60 may then perform machine learning to generate a trained model of what level of squeegee printing pressure is preferable for a given viscosity (e.g., whether the volume ratio is 100%). This trained model is a model for determining the squeegee printing pressure from the viscosity of the paste Pst. The control device 60 may use this trained model as relative information.

For example, when the viscosity of the paste Pst is 200 Pa·s, the control device 60 may learn whether a squeegee printing pressure of 70 degrees or 75 degrees is better for the volume fraction to approach 100%, and generate a trained model. In other words, a trained model may be generated by acquiring and learning a large amount of data on viscosity, squeegee printing pressure, and volume fraction as training data. The training data may be past performance information on the viscosity, squeegee printing pressure, and volume fraction. The control device 60 can determine the squeegee printing pressure based on the viscosity measured by the viscometer 47 according to the trained model as relative information.

The control device 60 may also generate a trained model by learning whether it is better to increase the current squeegee printing pressure by 5 N or 10 N in order to bring the volume ratio closer to 100% when the viscosity of the paste Pst has hardened by 20 Pa·s more than the viscosity at the time the current squeegee printing pressure was determined. In other words, the trained model may be generated by acquiring and learning a large amount of data on the amount of change in viscosity, the amount of change in squeegee printing pressure, and the volume ratio as training data. The control device 60 can determine the squeegee printing pressure based on the viscosity measured by the viscometer 47 according to the trained model as relative information.

The filling force of the paste Pst changes depending on the squeegee pressure, so the squeegee pressure affects the printing condition. In contrast, the printing device 100 determines the squeegee pressure based on the relative information of the viscosity of the paste Pst, the squeegee pressure, and the volume ratio, so that it can determine a squeegee pressure suitable for the viscosity, can achieve the desired volume ratio, and can maintain a good printing condition. In addition, the printing device 100 can evaluate the optimal squeegee pressure according to the viscosity of the paste Pst and derive the relative information with high accuracy. The squeegee pressure determined based on this relative information is highly reliable, so there is a low possibility that the printing condition will be poor and the volume ratio will be outside the acceptable range. In this case, the printing device 100 can suppress a decrease in printing accuracy even if the determination of the volume ratio in S18 of FIG. 7 is omitted.

In this way, the printing device 100 can change the printing conditions to match the increase in viscosity, even if the viscosity of the paste Pst such as solder increases due to being left unattended. Therefore, the printing device 100 can suppress printing defects caused by changes in the viscosity of the paste Pst such as solder, without adjusting the viscosity of the paste Pst such as solder.

As described above, the printing device 100 of this embodiment uses the squeegee 42 that slides over the screen mask 13 (an example of a mask) to print the paste Pst (an example of a solder paste) on the substrate 2 (an example of a substrate) through the pattern openings 13h (an example of an opening) provided in the screen mask 13. The printing device 100 includes a viscometer 47 and a control device 60 (an example of a processor). The viscometer 47 measures the viscosity of the paste Pst placed on the screen mask 13. The control device 60 determines the printing conditions for printing the paste Pst with the squeegee 42 based on the viscosity of the paste Pst measured by the viscometer 47.

As a result, the printing device 100 determines printing conditions that match the viscosity characteristics of the solder or other paste Pst, and therefore can suppress printing defects caused by changes in the viscosity of the solder or other paste Pst without adjusting the viscosity of the solder or other paste Pst. Furthermore, the printing device 100 does not require a device for adjusting the viscosity of the solder or other paste Pst, and therefore the printing device 100 can be prevented from becoming larger. Furthermore, the printing device 100 does not require time to adjust the viscosity of the solder or other paste Pst, and therefore can shorten the printing time. Furthermore, no manual measures are required for printing.

The viscometer 47 may also measure the viscosity of the paste Pst multiple times. The control device 60 may determine the printing conditions based on the change in the viscosity of the paste Pst.

This allows the printing device 100 to determine printing conditions in response to changes in the viscosity of the paste Pst, such as solder, over time.

The printing device 100 may also include a communication device 91 that acquires a volume ratio indicating the amount of paste Pst filled relative to the size of the opening 13h of the screen mask 13 from a solder printing inspection device 300 that inspects the printing state of the paste Pst. The control device 60 may determine printing conditions based on the volume ratio of the paste Pst.

As a result, the printing device 100 can appropriately adjust the amount of paste Pst filled by determining the printing conditions taking into account the volume ratio of the paste Pst. Therefore, the printing device 100 can print while preventing excess or deficiency of the paste Pst filled.

Furthermore, the printing device 100 and the communication device 91 may obtain the volume ratio multiple times. The control device 60 may repeatedly change the printing conditions until the volume ratio falls within the range of the predetermined volume ratio.

This allows the printing device 100 to print while keeping the excess or deficiency of the filled paste Pst within an acceptable range. In addition, compared to converging the volume ratio to a single desired value, the convergence speed is faster, and the printing device 100 can reduce the time required to complete the change in printing conditions.

The printing device 100 may also include a memory 93. The control device 60 may store in the memory 93 performance information on viscosity measured multiple times in the past by the viscometer 47, performance information on printing conditions determined multiple times in the past, and performance information on volume ratio acquired multiple times in the past from the solder print inspection device 300 corresponding to the performance information on viscosity and the performance information on printing conditions. The control device 60 may generate correlation information indicating the correlation between the viscosity, the printing conditions, and the volume ratio based on the performance information on viscosity, the performance information on printing conditions, and the performance information on volume ratio. The control device 60 may determine the printing conditions based on the viscosity measured by the viscometer 47 and the correlation information.

For example, the printing device 100 can generate linear correlation information between the squeegee angle and the volume ratio by mapping each point of the squeegee angle and each point of the volume ratio for each viscosity onto a two-dimensional plane and linearly approximating the squeegee angle and the volume ratio based on the actual information on the viscosity of the paste Pst, the actual information on the printing conditions, and the actual information on the volume ratio. For example, when the viscosity is 200 Pa·s, the printing device 100 refers to the correlation information and determines the squeegee angle to be 50 degrees so that the volume ratio is 100%. As a result, the more actual information the printing device 100 obtains, the more appropriate correlation information it can derive, improving the accuracy of determining the printing conditions and improving printing accuracy.

The printing conditions may also include a squeegee angle, which is the angle of the squeegee 42 relative to the screen mask 13. The control device 60 may reduce the squeegee angle as the viscosity measured by the viscometer 47 increases, and may increase the squeegee angle as the viscosity measured by the viscometer 47 decreases.

As a result, when the viscosity of the paste Pst is high, the printing device 100 can reduce the squeegee angle to increase the filling force of the paste Pst and prevent underprinting. Also, when the viscosity of the paste Pst is low, the printing device 100 can reduce the filling force of the paste Pst and prevent overprinting by increasing the squeegee angle.

The printing conditions may also include a squeegee printing pressure, which is the pressure of the squeegee 42 against the screen mask 13. The control device 60 may increase the squeegee printing pressure as the viscosity measured by the viscometer 47 increases, and may decrease the squeegee printing pressure as the viscosity measured by the viscometer 47 decreases.

As a result, when the viscosity of the paste Pst is high, the printing device 100 can increase the squeegee printing pressure to increase the filling force of the paste Pst and prevent underprinting. Also, when the viscosity of the paste Pst is low, the printing device 100 can decrease the squeegee printing pressure to decrease the filling force of the paste Pst and prevent overprinting.

Although various embodiments have been described above with reference to the drawings, it goes without saying that the present disclosure is not limited to such examples. It is clear that a person skilled in the art can come up with various modified or amended examples within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure. Furthermore, the components in the above embodiments may be combined in any manner as long as it does not deviate from the spirit of the present disclosure.

In the above embodiment, the processor may be physically configured in any way. If a programmable processor is used, the processing contents can be changed by changing the program, which increases the freedom of processor design. The processor may be configured as one semiconductor chip, or may be physically configured as multiple semiconductor chips. When configured as multiple semiconductor chips, each control in the above embodiment may be realized by a separate semiconductor chip. In this case, it can be considered that the multiple semiconductor chips constitute one processor. The processor may be configured as a semiconductor chip and a component (such as a capacitor) that has a different function. A single semiconductor chip may be configured to realize the functions of the processor and other functions. Multiple processors may be configured as a single processor.

This disclosure is useful for a printing device and printing method that can suppress printing defects caused by changes in the viscosity of the solder without adjusting the viscosity of the solder.

100 Printing device 2 Substrate 2d Electrode 11 Base 12 Substrate holding and moving mechanism 13 Screen mask 13h Opening 14 Carry-in conveyor 15 Carry-out conveyor 16 Camera 16a Upper imaging section 16b Lower imaging section 16K Camera moving mechanism 17 Squeegee head 21 Substrate holding section 22 Moving table section 31 Positioning conveyor 33 Clamp 33F Front clamper 33R Rear clamper 41 Moving base 42 Squeegee 42F Front squeegee 42R Rear squeegee 43 Squeegee lifting cylinder 46 Viscometer lifting cylinder 47 Viscometer 60 Control device 60a Image processing section 81 Servo driver 83 Servo motor 85 Electropneumatic regulator 87 Viscometer controller 91 Communication device 93 Memory OP Worker Pst Paste

Claims (6)

A printing device that prints solder paste on a substrate through an opening in a mask using a squeegee that slides on the mask, comprising:
a viscometer for measuring the viscosity of the solder paste disposed on the mask;
a processor that determines printing conditions for printing the solder paste with the squeegee based on the viscosity of the solder paste measured by the viscometer;
a communication device that acquires a volume ratio indicating a filling amount of the solder paste relative to a size of the opening of the mask from a solder print inspection device that inspects a printing state of the solder paste;
Memory,
Equipped with
The processor,
accumulating in the memory performance information of the viscosity measured a plurality of times in the past by the viscometer, performance information of the printing conditions determined a plurality of times in the past, and performance information of the volume ratio obtained a plurality of times in the past from the solder print inspection device corresponding to the performance information of the viscosity and the performance information of the printing conditions;
generating correlation information indicating a correlation between the viscosity, the printing conditions, and the volume ratio based on the performance information of the viscosity, the performance information of the printing conditions, and the performance information of the volume ratio;
determining the printing conditions based on the viscosity measured by the viscometer and the correlation information;
Printing device. The viscometer measures the viscosity of the solder paste multiple times;
the processor determines the printing conditions based on a change in viscosity of the solder paste.
The printing device of claim 1 . The communication device acquires the volume ratio a plurality of times;
the processor repeats changing the printing conditions until the volume ratio falls within a predetermined volume ratio range.
The printing device of claim 1 . the printing conditions include a squeegee angle, which is an angle of the squeegee with respect to the mask;
The processor,
The greater the viscosity measured by the viscometer, the smaller the squeegee angle is,
The smaller the viscosity measured by the viscometer, the larger the squeegee angle.
The printing device according to any one of claims 1 to 3 . the printing conditions include a squeegee printing pressure, which is a pressing force of the squeegee against the mask;
The processor,
The larger the viscosity measured by the viscometer, the larger the squeegee printing pressure is,
The smaller the viscosity measured by the viscometer, the smaller the squeegee printing pressure.
The printing device according to any one of claims 1 to 4 . A printing method for printing solder paste on a substrate through an opening in a mask using a squeegee that slides over the mask, comprising:
measuring the viscosity of the solder paste disposed on the mask;
determining printing conditions for printing the solder paste by the squeegee based on the measured viscosity of the solder paste;
acquiring a volume ratio indicating a filling amount of the solder paste relative to a size of the opening of the mask from a solder print inspection device that inspects a printing state of the solder paste;
accumulating in a memory performance information of the viscosity measured a plurality of times in the past by a viscometer, performance information of the printing conditions determined a plurality of times in the past, and performance information of the volume ratio obtained a plurality of times in the past from the solder print inspection device corresponding to the performance information of the viscosity and the performance information of the printing conditions;
generating correlation information indicating a correlation between the viscosity, the printing conditions, and the volume ratio based on the performance information on the viscosity, the performance information on the printing conditions, and the performance information on the volume ratio;
determining the printing conditions based on the viscosity measured by the viscometer and the correlation information;
A printing method comprising the steps of:

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