Printing apparatus and printing method

Abstract

To retain a printing quality while suppressing damages on a surface of a matter to be printed in printing using two squeegees.SOLUTION: A printer includes a printing part, a measurement part and a control part. The printing part prints paste on a matter to be printed via an opening of a printing mask by sequentially moving two squeegees on the printing mask. The measurement part measures a film thickness of printed paste. The control part controls each of the parts. The control part controls printing pressure of the one squeegee which moves last in the two squeegees based on a measurement result of a film thickness by the measurement part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a printing apparatus and a printing method.

Background Art

[0002] Conventionally, there is a printing apparatus that performs printing using a screen printing method. In such a printing apparatus, a printing mask is placed on a printing object, and a squeegee is moved on the printing mask, so that paste is printed on the printing object through an opening of the printing mask.

[0003] Here, the wear of the squeegee moving on the printing mask affects the printing quality. The film thickness of the paste printed on the printing object tends to increase as the wear of the squeegee increases. For this reason, various methods for managing the film thickness of the paste have been proposed. For example, a technique is known in which after printing the paste using a squeegee, the film thickness of the paste is measured, and the printing pressure of the squeegee is controlled based on the measurement result of the film thickness.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, some recent printing devices use two squeegees for printing. In such a printing device, paste is printed onto the substrate through the openings of the printing mask by sequentially moving the two squeegees over the printing mask. At this time, the first squeegee to move (hereinafter referred to as the "first squeegee") pushes the paste out through the openings of the printing mask and applies a relatively thin layer to the substrate. Meanwhile, the last squeegee to move (hereinafter referred to as the "second squeegee") pushes the paste out through the openings of the printing mask and applies a further layer to the substrate, adjusting the thickness of the paste to the desired thickness.

[0006] If the printing pressure of these two squeegees is uniformly controlled based on the measurement results of the paste film thickness described above, there is a risk of damaging the surface of the substrate. In other words, in printing using two squeegees, as the paste film thickness increases, the printing pressure of the first squeegee increases along with the printing pressure of the second squeegee. When the printing pressure of the first squeegee increases, the tip of the first squeegee passes through the opening of the printing mask and comes into contact with the surface of the substrate that has not yet been coated with paste. As a result, the surface of the substrate may be scratched by the tip of the first squeegee, potentially causing damage to the substrate's surface.

[0007] The disclosed technology has been made in view of the above, and aims to provide a printing apparatus and printing method that can maintain print quality while suppressing damage to the surface of the substrate in printing using two squeegees. [Means for solving the problem]

[0008] In one embodiment, the printing apparatus disclosed herein includes a printing unit, a measuring unit, and a control unit. The printing unit prints paste onto a workpiece through the openings of a printing mask by sequentially moving two squeegees over the printing mask. The measuring unit measures the film thickness of the printed paste. The control unit controls each unit. Based on the film thickness measurement result from the measuring unit, the control unit controls the printing pressure of the last of the two squeegees to move. [Effects of the Invention]

[0009] According to one embodiment of the printing apparatus disclosed in this application, in printing using two squeegees, it is possible to maintain print quality while suppressing damage to the surface of the substrate. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a left side view showing an example of the configuration of a printing apparatus according to an embodiment. [Figure 2] Figure 2 is a side view of the printing section according to the embodiment, viewed from the positive X-axis direction. [Figure 3] Figure 3 shows an example of a printing pressure control amount table according to the embodiment. [Figure 4] Figure 4 is a flowchart showing an example of the processing operation of the printing apparatus according to this embodiment. [Modes for carrying out the invention]

[0011] Embodiments of the printing apparatus and printing method disclosed herein will be described in detail below with reference to the drawings. However, these embodiments do not limit the disclosed technology.

[0012] In the following diagrams, for the sake of clarity, mutually orthogonal X, Y, and Z axis directions are defined, and a Cartesian coordinate system is shown with the positive Z axis pointing vertically upward.

[0013] Furthermore, here we define the front-to-back direction with the negative X-axis as forward and the positive X-axis as backward, and the left-to-right direction with the positive Y-axis as right and the negative Y-axis as left. We also define the up-and-down direction with the positive Z-axis as upward and the negative Z-axis as downward.

[0014] The configuration of the printing apparatus 1 according to this embodiment will be described with reference to Figure 1. Figure 1 is a left side view showing an example of the configuration of the printing apparatus 1 according to this embodiment. The printing apparatus 1 shown in Figure 1 prints paste P onto a substrate W, which is the object to be printed, using a screen printing method. As the paste P, for example, flux or solder paste can be used. The printing apparatus 1 has a printing unit 2, a transport unit 3, and a measuring unit 4.

[0015] Figure 2 is a side view of the printing unit 2 according to the embodiment, viewed from the positive X-axis direction. As shown in Figure 2, the printing unit 2 includes a holding base 21, a printing mask 22, a first squeegee 23_1, a second squeegee 23_2, a first lifting mechanism 24_1, a second lifting mechanism 24_2, and a movable plate 25. In the following, the first squeegee 23_1 and the second squeegee 23_2 may be collectively referred to as "squeegee 23". Also, the first lifting mechanism 24_1 and the second lifting mechanism 24_2 may be collectively referred to as "lifting mechanism 24".

[0016] The support stand 21 holds the substrate W horizontally.

[0017] The printing mask 22 is, for example, a plate-shaped member made of metal. The printing mask 22 is also called a screen plate. The printing mask 22 has openings (not shown) having a predetermined pattern. The printing mask 22 is configured to be movable between a printing position that is in contact with the substrate W and a retracted position located above the printing position.

[0018] The two squeegees 23 are elastic members made of, for example, resin rubber or the like. The two squeegees 23 are arranged side by side along the left - right direction. The two squeegees 23 are respectively attached to two lifting mechanisms 24 for lifting and lowering the two squeegees 23. Specifically, the first squeegee 23_1 is attached to the first lifting mechanism 24_1 and can be lifted and lowered in the vertical direction by the first lifting mechanism 24_1. Also, the second squeegee 23_2 is attached to the second lifting mechanism 24_2 and can be lifted and lowered in the vertical direction by the second lifting mechanism 24_2.

[0019] The two lifting mechanisms 24 are attached to the moving plate 25. The squeegee 23 is attached to the lower end of the lifting mechanism 24. The lifting mechanism 24 supports the squeegee 23 rotatably about an axis parallel to the front - rear direction. The lifting mechanism 24 lifts and lowers the squeegee 23. Specifically, the lifting mechanism 24 has an actuator, and the rod 24a is extended and contracted by the driving force of such an actuator to lift and lower the squeegee 23. By lifting and lowering the squeegee 23, the lifting mechanism 24 can change the pressing force (i.e., printing pressure) of the squeegee 23 against the printing mask 22. Specifically, the lifting mechanism 24 can increase the printing pressure of the squeegee 23 by extending the rod 24a to lower the squeegee 23, and can decrease the printing pressure of the squeegee 23 by retracting the rod 24a to raise the squeegee 23. Note that the lifting mechanism 24 may be any mechanism as long as it can obtain the driving force for extending and contracting the rod 24a. For example, it may be a mechanism that obtains the driving force for extending and contracting the rod 24a by pneumatic pressure, hydraulic pressure, or the like.

[0020] The moving plate 25 is attached to a guide rail (not shown) extending in the left - right direction and is movable in the left - right direction along the guide rail by a driving part such as a linear motor.

[0021] Such a printing unit 2 prints the paste P on the substrate W through the opening of the printing mask 22 by sequentially moving the two squeegees 23 on the printing mask 22.

[0022] That is, when the printing unit 2 holds the substrate W carried into the printing unit 2 on the holding table 21, it moves the printing mask 22 from the retracted position to the printing position and brings the printing mask 22 into contact with the substrate W. Paste P is placed on the printing mask 22 in advance. Subsequently, the printing unit 2 presses the first squeegee 23_1 against the printing mask 22 by lowering the first squeegee 23_1 out of the two squeegees 23 using the first lifting mechanism 24_1. Subsequently, the printing unit 2 moves the first squeegee 23_1 rightward on the printing mask 22 together with the first lifting mechanism 24_1 by moving the moving plate 25 rightward. As a result, the paste P placed on the printing mask 22 is extruded from the opening of the printing mask 22 and applied to the substrate W. When the movement of the first squeegee 23_1 ends, the printing unit 2 raises the first squeegee 23_1 using the first lifting mechanism 24_1. Subsequently, the printing unit 2 presses the second squeegee 23_2 against the printing mask 22 by lowering the second squeegee 23_2 using the second lifting mechanism 24_2. Subsequently, the printing unit 2 moves the second squeegee 23_2 leftward on the printing mask 22 together with the second lifting mechanism 24_2 by moving the moving plate 25 leftward. As a result, the paste P placed on the printing mask 22 is extruded from the opening of the printing mask 22 and applied to the substrate W. When the movement of the second squeegee 23_2 ends, the printing unit 2 raises the second squeegee 23_2 using the second lifting mechanism 24_2. Subsequently, the printing unit 2 moves the printing mask 22 from the printing position to the retracted position, completing the printing of the paste P on one substrate W.

[0023] Return to the description of FIG. 1. The conveyance unit 3 is provided between the printing unit 2 and the measurement unit 4 and has a substrate conveyance device 31 inside. The substrate conveyance device 31 has a substrate holding mechanism for holding the substrate W. Further, the substrate conveyance device 31 can move in the front-rear direction and the vertical direction, and conveys the substrate W between the printing unit 2 and the measurement unit 4 using the substrate holding mechanism.

[0024] The measurement unit 4 measures the film thickness of the paste P printed on the substrate W. The measurement unit 4 has a holding table 41 and a film thickness sensor 42. The holding table 41 holds the substrate W horizontally.

[0025] The film thickness sensor 42 measures the film thickness of the paste P printed on the substrate W in a non-contact manner. As the film thickness sensor 42, for example, a spectral interference film thickness sensor can be used, which irradiates the substrate W with laser light and measures the film thickness from the interference state of the light reflected from the front and back surfaces of the paste P.

[0026] When the substrate W on which paste P has been printed by the printing unit 2 is transported to the measuring unit 4 by the transport unit 3, the measuring unit 4 holds the substrate W on a holding stand 41 and measures the thickness of the paste P using a thickness sensor 42.

[0027] Furthermore, the printing device 1 includes a control device 5. The control device 5 is, for example, a computer and comprises a control unit 51 and a storage unit 52. The storage unit 52 stores programs that control various processes performed in the printing device 1. The control unit 51 controls the operation of the printing device 1 by reading and executing the programs stored in the storage unit 52.

[0028] Such a program may have been recorded on a computer-readable storage medium and installed from that storage medium to the storage unit 52 of the control device 5. Examples of computer-readable storage mediums include hard disks (HDs), flexible disks (FDs), compact disks (CDs), magnetic optical disks (MOs), and memory cards.

[0029] Incidentally, in the printing apparatus 1, as printing is performed sequentially on multiple substrates W, the squeegee 23 in the printing unit 2 gradually wears down, causing the film thickness of the paste P printed on the substrates W to fluctuate. In other words, the film thickness of the paste P printed on the substrates W tends to increase as the wear of the squeegee 23 increases.

[0030] In response to this, a technique for controlling the film thickness of paste P could be considered, which involves measuring the film thickness of paste P and controlling the printing pressure of the two squeegees 23 based on the measurement results. For example, the printing pressure of the two squeegees 23 could be uniformly increased as the film thickness of paste P increases.

[0031] However, in a technique where the printing pressure of the two squeegees 23 is uniformly increased as the film thickness of the paste P increases, the tip of the first squeegee 23_1, which moves first among the two squeegees 23, passes through the opening of the printing mask 22 and comes into contact with the surface of the substrate W, which has not yet been coated with paste P. As a result, the tip of the first squeegee 23_1 may scratch the surface of the substrate W, potentially causing damage to the substrate W surface.

[0032] Therefore, in the printing apparatus 1 according to the embodiment, the control unit 51 controls the printing pressure of the second squeegee 23_2, which moves last among the two squeegees 23, by controlling the second lifting mechanism 24_2 based on the measurement result of the thickness of the printed paste P. As a result, after the paste P is applied to the substrate W to a certain thickness by the first squeegee 23_1, the thickness of the paste P is adjusted to the desired thickness by the second squeegee 23_2 while the surface of the substrate W is covered with paste P. At this time, even if the tip of the second squeegee 23_2 passes through the opening of the printing mask 22, the surface of the substrate W is protected by the paste P that has already been applied, so the surface of the substrate W is less likely to be damaged by the tip of the second squeegee 23_2. As a result, in printing using two squeegees 23, it is possible to maintain printing quality while suppressing damage to the surface of the substrate W.

[0033] Furthermore, the control unit 51 controls the printing pressure of the second squeegee 23_2 by a control amount corresponding to the difference between the film thickness measured by the measurement unit 4 and a predetermined target value, by referring to the printing pressure control amount table shown in Figure 3. Figure 3 is a diagram showing an example of a printing pressure control amount table according to the embodiment. The printing pressure control amount table shown in Figure 3 is a table that stores the printing pressure control amount ΔP (MPa) of the second squeegee 23_2 associated with each difference α (μm) from a predetermined target value β of the film thickness of the paste P, and is created in advance by simulation or the like and stored in the storage unit 52. The difference α is a value calculated according to the following formula (1). α = (film thickness of paste P) - β ... (1) Here, equation (1) indicates that when the difference α is a positive value, the film thickness of paste P is greater than the target value β, and when the difference α is a negative value, the film thickness of paste P is less than the target value β.

[0034] The control unit 51 refers to the printing pressure control amount table and determines a printing pressure control amount ΔP corresponding to the difference α between the film thickness measured by the measurement unit 4 and a predetermined target value β. The control unit 51 controls the printing pressure of the second squeegee 23_2 by controlling the second lifting mechanism 24_2 with the printing pressure control amount ΔP. For example, if the difference α is 1.5 (μm), the control unit 51 increases the printing pressure of the second squeegee 23_2 by 0.02 (MPa). Also, for example, if the difference α is -2.5 (μm), the control unit 51 decreases the printing pressure of the second squeegee 23_2 by 0.03 (MPa).

[0035] The control unit 51 increases or decreases the printing pressure of the second squeegee 23_2 according to the difference α, thereby bringing the film thickness of the paste P measured by the measuring unit 4 closer to the target value β. That is, when the difference α is a positive value, i.e., when the film thickness of the paste P is greater than the target value β, the film thickness of the paste P can be reduced toward the target value β by increasing the printing pressure of the second squeegee 23_2. Also, when the difference α is a negative value, i.e., when the film thickness of the paste P is less than the target value β, the film thickness of the paste P can be increased toward the target value β by decreasing the printing pressure of the second squeegee 23_2.

[0036] In this way, the control unit 51 controls the second squeegee 23_2 with a printing pressure control amount ΔP determined from the film thickness measured by the measurement unit 4 by referring to the printing pressure control amount table, thereby quickly bringing the film thickness of the paste P closer to the target value β without performing complex calculations.

[0037] Incidentally, if the printing pressure of the second squeegee 23_2 increases or decreases excessively and deviates from the acceptable range, various problems may occur. For example, if the printing pressure of the second squeegee 23_2 exceeds a predetermined upper limit, the load applied from the second squeegee 23_2 to the printing mask 22 will increase, and the printing mask 22 may be damaged. Also, for example, if the printing pressure of the second squeegee 23_2 falls below a predetermined lower limit, the second squeegee 23_2 may separate from the printing mask 22, and a printing defect may occur in which the paste P placed on the printing mask 22 is not pushed out through the opening of the printing mask 22.

[0038] Therefore, the control unit 51 calculates the added printing pressure by adding the printing pressure control amount ΔP corresponding to the difference α between the film thickness measured by the measurement unit 4 and a predetermined target value β to the current value of the printing pressure of the second squeegee 23_2, and may notify an alert if the added printing pressure exceeds the upper limit or falls below the lower limit. The alert may be notified in any way that can inform the administrator of the printing device 1 of the abnormality. For example, the control unit 51 may display a message notifying the abnormality on a user interface (not shown) such as a display device of the printing device 1.

[0039] As a result, the printing apparatus 1 according to this embodiment can provide advance notification of a malfunction in the printing apparatus 1 caused by the printing pressure of the second squeegee 23_2 deviating from the permissible range.

[0040] Next, the processing operation of the printing apparatus 1 according to the embodiment will be described with reference to Figure 4. Figure 4 is a flowchart showing an example of the processing operation of the printing apparatus 1 according to the embodiment. Each process shown in Figure 4 is executed according to the control of the control unit 51. The processing operation shown in Figure 4 is started at a predetermined timing, for example, when the substrate W is held in the holder 21 of the printing unit 2.

[0041] First, the control unit 51 controls the printing unit 2 to sequentially move the two squeegees 23 over the printing mask 22, thereby printing paste P onto the substrate W through the openings in the printing mask 22 (step S101). Specifically, the control unit 51 prints paste P onto the substrate W by moving the first squeegee 23_1 and the second squeegee 23_2 over the printing mask in this order. Once the printing of paste P onto the substrate W is complete, the control unit 51 controls the transport unit 3 to transport the substrate W from the holding table 21 of the printing unit 2 to the holding table 41 of the measuring unit 4.

[0042] Next, the control unit 51 controls the measuring unit 4 to measure the thickness of the paste P printed on the substrate W (step S102).

[0043] Next, the control unit 51 refers to the printing pressure control amount table using the film thickness measured by the measurement unit 4 and determines the printing pressure control amount ΔP corresponding to the difference α between the film thickness measured by the measurement unit 4 and a predetermined target value β (step S103). Then, the control unit 51 adds the determined printing pressure control amount ΔP to the current value of the printing pressure of the second squeegee 23_2 to calculate the added printing pressure (step S104).

[0044] Next, the control unit 51 determines whether the added printing pressure exceeds a predetermined upper limit (step S105). If the added printing pressure does not exceed the predetermined upper limit (step S105; No), the control unit 51 determines whether the added printing pressure falls below a predetermined lower limit (step S106).

[0045] If the added printing pressure does not fall below a predetermined lower limit (step S106; No), the control unit 51 controls the printing pressure of the second squeegee 23_2 by controlling the second lifting mechanism 24_2 with the printing pressure control amount ΔP determined in step S103 (step S107).

[0046] On the other hand, if the added printing pressure exceeds a predetermined upper limit (step S105; Yes) or falls below a predetermined lower limit (step S106; Yes), the control unit 51 notifies an alert (step S108).

[0047] When the processes in steps S107 and S108 are completed, the control unit 51 controls a transport unit (not shown) to transport the substrate W from the holding table 41 of the measuring unit 4 to the outside of the printing device 1 (step S109), thereby completing the process.

[0048] Furthermore, while performing the processing operation shown in Figure 4, the control unit 51 may control the first lifting mechanism 24_1 to control the printing pressure of the first squeegee 23_1 so that the printing pressure of the first squeegee 23_1 is a constant value lower than the printing pressure of the second squeegee 23_2.

[0049] (Other variations) In the above embodiment, the case where the printing pressure of the second squeegee 23_2 is controlled based on the film thickness measurement result by the measuring unit 4 was described as an example, but other printing parameters other than printing pressure may also be controlled. For example, the control unit 51 may control the movement speed or angle of the second squeegee 23_2 based on the film thickness measurement result by the measuring unit 4. Alternatively, for example, the control unit 51 may control at least one of the printing pressure, movement speed, and angle of the second squeegee 23_2 based on the film thickness measurement result by the measuring unit 4.

[0050] As described above, the printing apparatus according to the embodiment (for example, printing apparatus 1) includes a printing unit (for example, printing unit 2), a measuring unit (for example, measuring unit 4), and a control unit (for example, control unit 51). The printing unit prints paste onto a substrate (for example, a substrate W) through the openings of a printing mask (for example, a printing mask 22) by sequentially moving two squeegees (for example, a first squeegee 23_1 and a second squeegee 23_2) over the printing mask. The measuring unit measures the film thickness of the printed paste. The control unit controls each unit. Based on the film thickness measurement result by the measuring unit, the control unit controls the printing pressure of the last of the two squeegees to move (for example, the second squeegee 23_2). As a result, according to the printing apparatus according to the embodiment, printing quality can be maintained while suppressing damage to the surface of the substrate in printing using two squeegees.

[0051] Furthermore, the printing apparatus according to the embodiment may further include a storage unit (e.g., storage unit 52) ​​that stores a control amount table (e.g., printing pressure control amount ΔP) associated with each difference (e.g., difference α) from a predetermined target value of film thickness (e.g., target value β) of film thickness. The control unit may refer to the control amount table and control the printing pressure of one squeegee with a control amount corresponding to the difference between the film thickness measured by the measuring unit and the target value. As a result, the printing apparatus according to the embodiment can quickly bring the film thickness of the paste closer to the target value without performing complex calculations.

[0052] Furthermore, the control unit may calculate an added printing pressure by adding a control amount corresponding to the difference between the film thickness measured by the measuring unit and the target value to the current printing pressure of one of the squeegees, and may notify an alert if the added printing pressure exceeds a predetermined upper limit or falls below a predetermined lower limit. As a result, according to the printing apparatus of this embodiment, it is possible to be notified in advance of a malfunction of the printing apparatus caused by the printing pressure of one of the squeegees deviating from the acceptable range.

[0053] Furthermore, the control unit may control the printing pressure of the other squeegee so that the printing pressure of the other squeegee that moves first (for example, the first squeegee 23_1) is a constant value lower than the printing pressure of the other squeegee. As a result, according to the printing apparatus of this embodiment, when printing using two squeegees, it is possible to maintain print quality while suppressing damage to the surface of the material to be printed. [Explanation of symbols]

[0054] 1 Printing device 2 Printing Department 3. Conveying section 4 Measuring part 5 Control device 21 Holding stand 22 Printed Masks 23_1 First squeegee 23_2 Second squeegee 23 Squeegee 24_1 First Lifting Mechanism 24_2 Second Lifting Mechanism 24 Lifting mechanism 24a Rod 25 Mobile Plate 31. Substrate transport device 41 Holding stand 42 Film Thickness Sensor 51 Control Unit 52 Storage section W board

Claims

1. A printing unit that prints paste onto a substrate through the openings of a printing mask by sequentially moving two squeegees over the printing mask, A measuring unit for measuring the film thickness of the printed paste, A control unit that controls each part It has, The control unit, A printing apparatus characterized by controlling the printing pressure of one of the two squeegees that moves last, based on the measurement result of the film thickness by the measuring unit, and controlling the printing pressure of the other squeegee that moves first, so that the printing pressure of the other squeegee is a constant value lower than the printing pressure of the first squeegee.

2. The system further includes a storage unit that stores a control amount table, which stores the control amount of the printing pressure associated with each difference in the film thickness from a predetermined target value. The control unit, Referring to the control amount table, the printing pressure of one of the squeegees is controlled by the control amount corresponding to the difference between the film thickness measured by the measuring unit and the target value. The printing apparatus according to feature 1.

3. The control unit, The system calculates an added printing pressure by adding the control amount corresponding to the difference between the film thickness measured by the measuring unit and the target value to the current printing pressure of one of the squeegees, and if the added printing pressure exceeds a predetermined upper limit or falls below a predetermined lower limit, an alert is issued. The printing apparatus according to feature 2.

4. By sequentially moving two squeegees over the printing mask, paste is printed onto the substrate through the openings in the printing mask. The film thickness of the printed paste is measured, Based on the measurement results of the film thickness, the printing pressure of the last of the two squeegees to move is controlled, and the printing pressure of the other squeegee to move first is controlled so that the printing pressure of the other squeegee is a constant value lower than the printing pressure of the first squeegee. A printing method characterized by including a process.

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