JP7108827B2 - Screen printing device and screen printing method - Google Patents

Description

The present disclosure relates to a screen printing apparatus and a screen printing method for printing paste on a substrate.

A screen printing apparatus brings a substrate into contact with the lower surface of a mask in which a plurality of openings are formed, moves a squeegee over the mask, and presses a paste such as cream solder into the plurality of openings to transfer the paste to the substrate. After printing on a predetermined number of substrates, the screen printing apparatus performs cleaning to remove the paste adhering to the mask. It is known that the transfer amount of the paste printed on the substrate is reduced in printing immediately after cleaning (for example, see Patent Document 1). In the screen printing apparatus described in Patent Document 1, the attack angle of the squeegee is tilted more in printing immediately after cleaning than in normal printing to increase the amount of transfer so that there is no difference in the amount of paste transferred in normal printing. there is

JP-A-2007-237668

2. Description of the Related Art In cleaning a screen printing apparatus, a wet cleaning method using a solvent and a dry cleaning method not using a solvent may be performed at predetermined printing intervals. The degree of decrease in paste transfer amount in printing immediately after cleaning differs depending on the cleaning method. However, in the prior art such as Patent Document 1, the same printing conditions are applied immediately after cleaning regardless of the cleaning method. Therefore, the transfer amount of the printed paste may vary, and the print quality may vary.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a screen printing apparatus and a screen printing method that can reduce variations in paste printed on a substrate even when a plurality of cleaning methods are used.

The screen printing apparatus of the present disclosure is configured such that a mask having a plurality of openings for printing paste, a substrate holding portion for holding a substrate, and the substrate held by the substrate holding portion and the mask are brought into contact with each other. a print head that prints the paste on the mask onto the substrate through the plurality of openings in a state in which the mask is held; and a cleaning mechanism that can use a plurality of cleaning methods for cleaning the mask, wherein the plurality of After cleaning by the cleaning mechanism, the printing conditions for the print head to print the paste on the substrate are changed based on the number of times of application set for the cleaning method executed among the cleaning methods.

The screen printing method of the present disclosure is a screen printing method for printing a paste on a substrate, comprising: a substrate contacting step of contacting the substrate with a mask having a plurality of openings; a cleaning step of removing the paste adhering to the mask using one of a plurality of cleaning methods; and a printing condition changing step of changing printing conditions for printing the paste on the substrate by the print head based on the number of times of application.

According to the present invention, it is possible to reduce variations in paste printed on a substrate even when a plurality of cleaning methods are used.

FIG. 1 is an explanatory diagram of the configuration of a screen printing system according to an embodiment. FIG. 2 is a plan view showing the structure of the screen printing apparatus according to the embodiment. FIG. 3 is a side view showing the structure of the screen printing apparatus according to the embodiment. FIG. 4 is a functional explanatory diagram of a print head included in the screen printing apparatus according to the embodiment. FIG. 5 is a functional explanatory diagram of a cleaning mechanism included in the screen printing apparatus according to the embodiment. FIG. 6 is a block diagram showing the configuration of the control system of the screen printing apparatus according to the embodiment. FIG. 7 is a diagram showing an example of a printing condition correction information input screen in the screen printing apparatus according to the embodiment. FIG. 8 is a flow chart of the screen printing method of the embodiment. FIG. 9A is a diagram illustrating changes in the volume ratio of printed paste in the screen printing apparatus according to the embodiment. FIG. 9B is a diagram illustrating changes in the volume ratio of the printed paste in the screen printing apparatus according to the embodiment.

An embodiment of the present disclosure will be described in detail below with reference to the drawings. The configuration, shape, etc. described below are examples for explanation, and can be changed as appropriate according to the specifications of the screen printing system and the screen printing apparatus. In the following, the same reference numerals are given to the corresponding elements in all the drawings, and redundant explanations are omitted. Hereinafter, the substrate transport direction (horizontal direction in FIG. 2) is the X direction, the direction orthogonal to the X direction in the horizontal plane (vertical direction in FIG. 2) is the Y direction, and the direction orthogonal to the X and Y directions (in FIG. vertical direction) is defined as the Z direction.

First, the configuration of the screen printing system 1 will be described with reference to FIG. The screen printing system 1 is configured by serially connecting a screen printing device M1 and a print inspection device M2 from the upstream side (left side on the page) to the downstream side (right side on the page) in the substrate conveying direction. The screen printing device M1 and the print inspection device M2 are connected to the management computer 3 via the communication network 2. FIG. The management computer 3 stores production data including control programs used by the screen printing apparatus M1 and the print inspection apparatus M2, work histories of the screen printing apparatus M1 and the print inspection apparatus M2, inspection result information, and the like. The management computer 3 performs information transmission between the screen printing apparatus M1 and the print inspection apparatus M2, information transmission with other apparatuses, and the like. The screen printing system 1 is arranged upstream of a mounting board production line that mounts components on boards, and the boards that have been inspected by the print inspection apparatus M2 are conveyed to the component mounting apparatus downstream thereof.

The screen printing apparatus M1 prints paste on a substrate brought in from the upstream side through a mask having a plurality of openings. The print inspection device M2 includes an inspection camera and a three-dimensional sensor. The print inspection device M2 inspects the state and amount of paste printed on the upper surface of the substrate conveyed from the screen printer M1. The inspection result is transmitted to the management computer 3 and also to the screen printer M1.

First, the structure of the screen printing apparatus M1 will be described with reference to FIGS. 2 and 3. FIG. The screen printing apparatus M1 includes a pair of transport conveyors 5 extending in the X direction on a base 4. As shown in FIG. A controller C is provided on the base 4 . The transport conveyor 5 is controlled by the controller C, transports the substrate 6 received from the upstream side of the screen printing device M1 in the X direction, and carries it out to the downstream side of the screen printing device M1. A substrate holder 7 controlled by a controller C is provided near the center of the transport conveyor 5 in the X direction. The substrate holder 7 receives the substrate 6 conveyed by the conveyor 5 and holds it at a predetermined clamping position.

A plurality of openings 8a for printing paste on the substrate 6 and a mask 8 formed with a pair of mask-side marks 8m are provided above the substrate holding portion 7 . The mask 8 has a rectangular flat plate shape extending over the XY plane, and its outer periphery is supported by a frame member 8w.

In FIG. 3, an XY table 9, a .theta. table 10, and a substrate elevating mechanism 11 are provided on the base 4 in this order from below. The XY table 9 moves the θ table 10 in the horizontal plane (X direction, Y direction). The θ table 10 rotates the substrate lifting mechanism 11 about the Z axis by θ degrees. The substrate lifting mechanism 11 supports and lifts the substrate holder 7 from below. The XY table 9, the θ table 10, and the substrate lifting mechanism 11 are controlled by the controller C.

In FIG. 3, a camera unit 13 containing a substrate recognition camera and a mask recognition camera is provided below the mask 8 . The camera unit 13 moves in a horizontal plane (arrow a1) by a camera moving mechanism 14 (see FIG. 6) controlled by the controller C. As shown in FIG. The camera unit 13 moves between the substrate 6 and the mask 8 to pick up images of substrate-side marks for alignment formed on the substrate 6 and mask-side marks 8m for alignment formed on the mask 8 . The controller C recognizes the positions of the mask-side mark 8m and the substrate-side mark based on the image captured by the camera unit 13. FIG.

Next, based on the recognition result, the controller C adjusts the XY table 9 and θ The positions and orientations of the table 10 and substrate lifting mechanism 11 are controlled. Next, the controller C raises the substrate holder 7 to bring the substrate 6 into contact with the mask 8 from below. As described above, the substrate holding part 7 is provided below the mask 8 , and the XY table 9 , the θ table 10 , and the substrate lifting mechanism 11 move the substrate holding part 7 to move the substrate held by the substrate holding part 7 . A substrate positioning mechanism 12 for aligning the substrate 6 with the mask 8 is constructed.

In FIGS. 2 and 3, above the mask 8, a print head 20 is provided which is moved in the Y direction by a print head moving mechanism 15 (see FIG. 6). The print head 20 has a movement base 21 that is moved in a horizontal plane by a print head movement mechanism 15 . Two squeegee holding portions 22 (a first squeegee holding portion 221 and a second squeegee holding portion 222) are arranged in the Y direction on the moving base 21 . The squeegee holding part 22 holds squeegees 23 (a first squeegee 231 and a second squeegee 232 ) extending in the X direction at their lower ends, and is lifted and lowered by an elevating mechanism 24 provided on the moving base 21 . The squeegee holding portion 22 incorporates an attack angle adjusting portion 25 for adjusting an attack angle θ (see FIG. 4), which is the inclination of the squeegee 23 when it contacts the mask 8 . The print head moving mechanism 15 and the print head 20 are controlled by the controller C. FIG.

Next, referring to FIG. 4, the movement operation of the print head 20 will be described. The moving operation is performed with the substrate 6 held by the substrate holder 7 aligned with the mask 8 . The controller C controls the attack angle adjuster 25 to set the squeegee 23 to a predetermined attack angle θ. Next, the controller C controls the lifting mechanism 24 to lower one squeegee 23 (first squeegee 231) (arrow b) and bring it into contact with the front side of the region in which the plurality of openings 8a are formed.

At this time, the controller C adjusts the contact force F for bringing the squeegee 23 into contact with the upper surface of the mask 8 according to the amount of descent of the squeegee 23 . Next, the controller C controls the print head moving mechanism 15 to move the squeegee 23 rearward in the Y direction at the moving speed V. FIG. When the squeegee 23 moves over the plurality of openings 8a, the paste Pst supplied to the upper surface of the mask 8 is pushed into the plurality of openings 8a with a predetermined printing pressure (pressure). The printing pressure when the paste Pst is pushed into the plurality of openings 8a can be adjusted by the attack angle θ, contact force F, and moving speed V of the squeegee 23 .

Specifically, at least one of decreasing the attack angle θ, increasing the contact force F, and increasing the moving speed V can increase the pressing pressure. By at least one of increasing the attack angle θ, decreasing the contact force F, and decreasing the moving speed V, the pressing pressure can be reduced.

When the squeegee 23 moves to the outside (rear side) of the region in which the plurality of openings 8a are formed, the controller C raises one squeegee 23 (for example, the first squeegee 231). Similarly to the one squeegee 23, the controller C lowers the other squeegee 23 (for example, the second squeegee 232) to contact the mask 8 and moves it forward in the Y direction to fill the plurality of openings 8a with the paste. Execute the moving action of pushing Pst. In this way, the print head 20 has a squeegee 23 that moves while contacting the upper surface of the mask 8 to push the paste Pst into the plurality of openings 8a. The substrate 6 is printed through the plurality of openings 8a.

In FIG. 3, a cleaning mechanism 30 for cleaning the paste Pst remaining on the back surface of the mask 8 is provided below the mask 8 and on the front side in the Y direction. The cleaning mechanism 30 is moved in the Y direction (arrow a2) by the cleaning movement mechanism 16 (see FIG. 6) controlled by the controller C. As shown in FIG. The cleaning mechanism 30 includes a wiping head 31 that extends in the X direction and moves up and down in the Z direction (arrow a3).

In the cleaning mechanism 30, a paper roll 33A around which unused cleaning paper 32 is wound and a paper roll 33B for collecting used cleaning paper 32 are mounted in front and behind in the Y direction sandwiching the wiping head 31. . The cleaning paper 32 pulled out from the paper roll 33A goes around the upper surface of the wiping head 31 and is wound around the paper roll 33B rotated by the roll rotation mechanism 34 controlled by the controller C. As shown in FIG. The cleaning mechanism 30 is controlled by the controller C and includes a cleaning liquid applying section 35 that applies a solvent that dissolves the paste Pst to the cleaning paper 32 .

Here, referring to FIG. 5, the mask cleaning operation for cleaning the paste Pst remaining on the back surface of the mask 8 will be described. During the mask cleaning operation, the control unit C performs mask cleaning by a wet cleaning method in which the cleaning liquid applying unit 35 applies a solvent to the cleaning paper 32 in a preset pattern, or a dry cleaning method that does not use a solvent. do.

In the wet cleaning method using a solvent, the controller C raises the wiping head 31, which circulates the cleaning paper 32 coated with the solvent by the cleaning liquid coating unit 35, and brings it into contact with the back surface of the mask 8 (arrow c1). Next, the controller C controls the cleaning movement mechanism 16 to move the cleaning mechanism 30 in the Y direction (arrow c2). In the dry cleaning method that does not use a solvent, the controller C causes the wiping head 31 to contact the back surface of the mask 8 with the cleaning paper 32 that is not coated with solvent, and moves the cleaning mechanism 30 in the Y direction.

As a result, the paste Pst remaining on the back surface of the mask 8 and the paste Pst remaining in the plurality of openings 8 a are wiped off with the cleaning paper 32 . The used cleaning paper 32 from which the paste Pst has been wiped off is wound around a paper roll 33B (see FIG. 3) rotated by the roll rotation mechanism 34, and the unused cleaning paper 32 is supplied to the upper surface of the wiping head 31. . Thus, the cleaning mechanism 30 removes the paste Pst adhering to the mask 8 using a plurality of cleaning methods (wet cleaning method, dry cleaning method). Note that the wiping head 31 may be provided with a vacuum suction mechanism, and may perform a suction cleaning method in which the mask is cleaned while performing vacuum suction.

The effect of mask cleaning will now be described with reference to FIG. 9A. In FIG. 9A, the amount (volume ratio) of the paste Pst transferred to the substrate 6, which is transported after screen printing and measured by the print inspection device M2, is displayed for each substrate 6 in order of work. In the screen printing apparatus M1, when screen printing is repeatedly performed without performing mask cleaning, the amount of the paste Pst protruding from the plurality of openings 8a of the mask 8 to the back surface gradually increases, and the amount of the paste Pst transferred to the substrate 6 increases. Gradually increase the amount. If the screen printing is continued as it is, the amount of the paste Pst transferred to the substrate 6 will exceed the specified value, so mask cleaning will be performed periodically.

When mask cleaning is performed after screen printing, part or all of the paste Pst remaining in the openings 8a of the mask 8 and the back surface is removed. Therefore, the amount of paste Pst transferred to the substrate 6 after mask cleaning is smaller than the amount transferred to the substrate 6 immediately before mask cleaning. In particular, wet cleaning using a solvent is more effective than dry cleaning in removing the flux component that acts as a lubricating oil on the surface of the opening 8a, and this tendency appears strongly. Therefore, in screen printing immediately after wet cleaning, the amount of paste Pst remaining in the openings 8a without being transferred to the substrate increases, and as a result, the amount of paste Pst transferred to the substrate 6 decreases.

Therefore, the reduction rate Dw after wet cleaning is greater than the reduction rate Dd after dry cleaning. For example, as shown in FIG. 9A, the fifth substrate 6 after dry cleaning has a lower volume ratio of the transferred paste Pst than the previous fourth substrate 6 by a reduction rate Dd. In addition, the ninth substrate 6 after wet cleaning has a volume ratio of the transferred paste Pst that is lower than that of the immediately preceding eighth substrate 6 by the reduction rate Dw. Thus, the reduction rate of the paste Pst printed on the substrate immediately after cleaning differs depending on the cleaning method.

Next, referring to FIG. 6, the configuration of the control system of the screen printer M1 will be described. The control unit C included in the screen printing apparatus M1 includes a transport conveyor 5, a substrate holding unit 7, a substrate positioning mechanism 12, a camera unit 13, a camera moving mechanism 14, a print head moving mechanism 15, a cleaning moving mechanism 16, a touch panel 17, a printing A head 20 and a cleaning mechanism 30 are connected. The touch panel 17 has a display function of displaying an operation screen of the screen printing apparatus M1 on the liquid crystal panel, and an input function of inputting commands and various information by operating the displayed operation screen.

The control section C includes a storage section 40 , a printing work processing section 41 , a cleaning processing section 42 and a correction information setting processing section 43 . The storage unit 40 is a storage device, and includes a printing condition storage unit 40a and a correction information storage unit 40b. The printing condition storage unit 40a stores, for each type of substrate 6, printing conditions for the print head 20 to print the paste Pst on the substrate 6, mask cleaning conditions including the timing for performing mask cleaning, and the like.

The printing conditions include the pressure (printing pressure) with which the print head 20 pushes the paste Pst into the plurality of openings 8a, the contact force F with which the squeegee 23 contacts the upper surface of the mask 8, the moving speed V of the squeegee 23, and the squeegee 23 being a mask. The angle of attack θ, which is the inclination when contacting with 8, is included. Also, the mask cleaning conditions store the timing for executing mask cleaning, the cleaning method, and the like.

An example of mask cleaning timing will now be described with reference to FIG. 9A. In this example, mask cleaning is performed after successive screen printing on four substrates 6 . Specifically, mask cleaning is performed after screen printing on the fourth, eighth, twelfth, sixteenth, and twentieth substrates 6 . Mask cleaning repeats the pattern of performing two dry cleanings followed by one wet cleaning. Specifically, dry cleaning is performed before the first sheet and after the fourth sheet, and wet cleaning is performed after the eighth sheet. Dry cleaning is performed after the 12th sheet and after the 16th sheet, and wet cleaning is performed after the 20th sheet.

In FIG. 6, the correction information setting processing unit 43 causes the touch panel 17 to display a printing condition correction information input screen for inputting printing condition correction information for correcting paste Pst that decreases after cleaning. It is stored in the correction information storage unit 40b. The management computer 3 may include the correction information setting processing section 43, and the printing condition correction information input in the management computer 3 may be transferred to the correction information storage section 40b for storage.

Here, an example of the printing condition correction information input screen 17a displayed on the touch panel 17 will be described with reference to FIG. The printing condition correction information input screen 17a includes a "correction after cleaning" column 50, a "gradual correction" column 51, a "contact pressure correction" column 52, a "moving speed correction" column 53, and an "attack angle correction" column 54. , the input fields of the "number of times of application" field 55 are set in the "wet cleaning" frame 56 and the "dry cleaning" frame 57, respectively. A "cancel" button 58 and a "register" button 59 are set on the printing condition correction information input screen 17a. Further, in the "contact pressure correction" column 52, the "moving speed correction" column 53, the "attack angle correction" column 54, and the "application count" column 55, an increase button "△" and a decrease button "▽" are provided to assist input. ” is set in the printing condition correction information input screen 17a.

In the "correction after cleaning" column 50, whether to correct the printing conditions after mask cleaning (valid) or not (invalid) is selected and input. In the "stepwise correction" column 51, whether to correct the printing conditions step by step (valid) or not (invalid) is selected and input. When the “gradual correction” column 51 is (valid), the printing conditions are corrected step by step by the number of times input in the “number of times of application” column 55 . The correction amount of the contact force F of the squeegee 23 is entered in the "contact pressure correction" column 52 in percentage. The correction amount of the moving speed V of the squeegee 23 is entered in the "moving speed correction" column 53 as a percentage. The correction amount of the attack angle θ of the squeegee 23 is input in the "attack angle correction" column 54 in degrees.

In FIG. 7, both wet cleaning and dry cleaning are entered as "effective" in the "correction after cleaning" column 50, and correction of printing conditions is executed after mask cleaning. In wet cleaning, "+10%" is entered in the "contact pressure correction" column 52, and the contact force F is corrected. Further, in the wet cleaning, the "gradual correction" column 51 is "valid" and "2" is entered in the "number of times of application" column 55, so the printing conditions are corrected step by step. That is, the contact force F is increased by 10% for the first sheet after wet cleaning, the contact force F is increased by 5% for the second sheet, and the correction is not performed for the third and subsequent sheets. By increasing the contact force F, the printing pressure is increased, and the reduction of the paste Pst after cleaning is corrected.

In the dry cleaning, "-15°" is entered in the "attack angle correction" column 54, and the attack angle θ is corrected. In the dry cleaning, the "gradual correction" column 51 is "invalid" and the "number of times of application" column 55 is "1", so the printing conditions are not corrected step by step. That is, the attack angle θ of the first sheet after dry cleaning is decreased by 15° (the squeegee 23 is laid down), and the second and subsequent sheets are not corrected. By decreasing the attack angle θ and tilting the squeegee 23, the printing pressure is increased, and the reduction of the paste Pst after cleaning is corrected.

In FIG. 7, when the "cancel" button 58 is operated, the information entered in each entry field of the printing condition correction information entry screen 17a is cleared. When the "Register" button 59 is operated, the information entered in each input column of the printing condition correction information input screen 17a is stored in the correction information storage section 40b as printing condition correction information. In this way, the printing conditions changed after cleaning are the pressure (contact force F) with which the print head 20 pushes the paste Pst into the plurality of openings 8a, the movement speed V at which the print head 20 moves over the mask 8, and the squeegee 23. It is at least one of the inclination (attack angle θ) when contacting the mask 8 .

In FIG. 6, the printing work processing unit 41 performs printing of the screen printer M1 including the print head 20 based on the printing conditions stored in the printing condition storage unit 40a and the printing condition correction information stored in the correction information storage unit 40b. Each unit is controlled to execute the screen printing work. Based on the printing condition correction information, the printing work processing unit 41 corrects the printing conditions a predetermined number of times (the number of times of application) after the mask cleaning, and causes the screen printing work to be executed.

The cleaning processing unit 42 controls the cleaning mechanism 30 and the cleaning movement mechanism 16 based on the mask cleaning conditions stored in the printing condition storage unit 40a to perform mask cleaning at a predetermined timing and in a predetermined method after screen printing. . In this way, after cleaning by the cleaning mechanism 30, the print work processing unit 41 changes the printing conditions for the print head 20 to print the paste Pst on the substrate 6 according to the cleaning method that has been performed, and causes screen printing to be performed.

Next, a screen printing method for printing the paste Pst on the substrate 6 by the screen printing device M1 will be described along the flow of FIG. 8 and with reference to FIG. 9B. The screen printing on the 43rd substrate 6 in FIG. 9B will be described below.

In FIG. 8, first, the printing work processing section 41 conveys the 43rd board 6 carried in from the upstream side by the carrying conveyor 5 to the board holding section 7, and holds the board 6 conveyed by the board holding section 7. (ST1: substrate loading step). Next, the printing work processing section 41 corrects the position based on the image captured by the camera unit 13, and brings the substrate 6 held by the substrate holding section 7 into contact with the lower surface of the mask 8 in which the plurality of openings 8a are formed. (ST2: Substrate contact step).

Next, the print job processing section 41 moves the print head 20 to push the paste Pst into the plurality of openings 8a based on the printing conditions stored in the printing condition storage section 40a (ST3: printing step). Next, the printing work processing section 41 lowers the substrate holding section 7 to separate the substrate 6 from the mask 8 (ST4: substrate separating step). Next, the printing work processing section 41 causes the board holding section 7 to release the board 6, and carries out the board 6 after the screen printing to the downstream side by the transfer conveyor 5 (ST5: board carry-out step). When the screen printing on the planned number of substrates 6 is completed (Yes in ST6), the printing process is completed.

If the printing process for the planned number of sheets has not been completed (No in ST6), the cleaning processing unit 42 determines whether it is time for mask cleaning based on the mask cleaning conditions stored in the printing condition storage unit 40a ( ST7: mask cleaning judgment step). In FIG. 9B, after printing the 43rd substrate 6, it is not the timing for mask cleaning (No in ST7). Therefore, the 44th substrate 6 is loaded in the substrate loading step (ST1), and the printing step (ST3) is executed under the printing conditions stored in the printing condition storage section 40a.

In FIG. 9B, after printing the 44th substrate 6, it is time for dry cleaning (Yes in ST7). In FIG. 8, when the substrate unloading step (ST5) of the 44th substrate 6 is completed, the cleaning processing unit 42 removes the paste Pst adhering to the mask 8 using a dry cleaning method (ST8: cleaning step ).

Next, the printing work processing section 41 determines whether or not the executed cleaning method is wet cleaning (ST9: cleaning method determination step). Since the cleaning method that was executed was the dry cleaning method (No in ST9), the printing work processing section 41 corrects the printing conditions based on the printing condition correction information after the dry cleaning stored in the correction information storage section 40b. (ST10: post-dry printing condition correction step).

In FIG. 8, the substrate loading step (ST1) is then carried in, the 45th substrate 6 is loaded, and the printing step (ST3) is executed under the printing conditions corrected in the post-dry printing condition correction step (ST9). In FIG. 9B, as a result, the corrected volume ratio Cd is added to correct the reduction ratio Dd after dry cleaning, and the transferred paste Pst has a volume ratio close to the target value.

Similarly, after the substrate unloading step (ST5) for the 48th substrate 6 is completed, the cleaning step (ST8) is performed using the wet cleaning method. Next, in the cleaning method determination step (ST9), it is determined that the wet cleaning method is used (Yes), and the print work processing section 41 sets the printing conditions based on the printing condition correction information after the wet cleaning stored in the correction information storage section 40b. Correct (ST11: post-wet printing condition correction step).

Next, the process returns to the substrate loading step (ST1), the 49th substrate 6 is loaded, and the printing step (ST3) is executed under the printing conditions corrected in the post-wet printing condition correction step (ST11). In FIG. 9B, as a result, the corrected volume ratio Cw is added to correct the reduction ratio Dw after wet cleaning, and the volume ratio of the transferred paste Pst becomes close to the target value.

Thus, in the cleaning step (ST8), the paste Pst adhering to the mask 8 is removed using one of a plurality of cleaning methods. The cleaning method determination step (ST9), the post-dry printing condition correcting step (ST10), and the post-wet printing condition correcting step (ST11) are performed after the cleaning step (ST8) so that the print head 20 is positioned on the substrate according to the cleaning method executed. 6 is a printing condition changing step (ST12) for changing the printing conditions for printing the paste Pst.

In the printing condition changing step (ST12), the pressure (contact force F ), the movement speed V at which the print head 20 moves over the mask 8 in the printing step (ST3), and the inclination (attack angle θ) when the squeegee 23 comes into contact with the mask 8 in the printing step (ST3). one is changed. Further, when stepwise correction is designated in the printing condition correction information, the printing process (ST3) is executed with the printing conditions corrected stepwise by the designated number of times of application. Thereafter, the printing process (ST3) is executed under the printing conditions stored in the printing condition storage section 40a.

As described above, the screen printing apparatus M1 of the present embodiment moves the mask 8 formed with the plurality of openings 8a for printing the paste Pst, the substrate holding section 7, and the substrate holding section 7. and a substrate positioning mechanism 12 for aligning the substrate 6 held by the substrate holding part 7 with the lower surface of the mask 8 . Further, the screen printer M1 uses a print head 20 that prints the paste Pst on the mask 8 onto the substrate 6 through a plurality of openings 8a, and a plurality of cleaning methods (wet cleaning method and dry cleaning method) to clean the mask 8. and a cleaning mechanism 30 capable of cleaning the lower surface of the .

After cleaning by the cleaning mechanism 30, the screen printer M1 changes the printing conditions for the print head 20 to print the paste Pst on the substrate 6 according to the cleaning method that has been performed. As a result, variations in the paste Pst printed on the substrate 6 can be reduced even when a plurality of cleaning methods are used.

Note that the screen printing apparatus M1 having the print head 20 having the squeegee 23 has been described above. However, the screen printing device is not limited to this form. For example, it may be a screen printing apparatus provided with a pressurizing print head having a pressurizing part for pushing out the paste Pst stored in the storage chamber onto the mask 8 . In that case, the printing conditions that are changed after cleaning to correct the paste Pst that decreases after cleaning are the force (pressure) applied by the pressure unit to the paste Pst in the storage chamber, or the pressure applied by the pressure type print head to the mask 8 . It is the movement speed V which moves upwards.

Further, the control unit C of the screen printing device M1 controls the printing condition correction information set based on the state, area, height, volume ratio, etc. of the paste Pst printed on the substrate 6 inspected by the printing inspection device M2. may be provided with a printing condition learning unit that automatically learns and adjusts the In this case, the printing condition learning unit adjusts the printing conditions so that the state of the paste Pst reaches a preset target state based on changes in the state of the paste Pst on the plurality of printed substrates 6 after cleaning. In addition, the printing condition learning unit 66 adjusts the state of the paste Pst to a preset target state based on the state (volume ratio) of the paste Pst on the plurality of substrates 6 having the same cleaning method executed immediately before. Adjust the printing conditions.

According to the present disclosure, variations in the paste printed on the substrate can be reduced even when a plurality of cleaning methods are used together.

The screen printing apparatus and screen printing method of the present disclosure have the effect of being able to reduce variations in the paste printed on the substrate even when a plurality of cleaning methods are used together, and mount electronic components on the substrate. useful in the field.

6 substrate 7 substrate holder 8 mask 8a opening 20 print head 23 squeegee 30 cleaning mechanism M1 screen printer Pst paste V moving speed θ attack angle (inclination)

Claims (20)

a mask having a plurality of openings for printing the paste;
a substrate holder that holds the substrate;
a print head that prints the paste on the mask onto the substrate through the plurality of openings while the substrate held by the substrate holding portion and the mask are in contact with each other;
a cleaning mechanism capable of using multiple cleaning schemes for cleaning the mask;
A screen printing apparatus that changes printing conditions for the print head to print paste on a substrate after cleaning by the cleaning mechanism based on the number of times of application set for the cleaning method executed among the plurality of cleaning methods. 2. The screen printing apparatus according to claim 1, wherein said printing conditions to be changed after said cleaning are set for each cleaning method performed. 2. The screen printing apparatus according to claim 1, wherein said printing conditions changed after said cleaning include pressure with which said print head presses paste into said plurality of openings. The print head is
a squeegee that moves while being in contact with the upper surface of the mask to push the paste into the plurality of openings;
2. The screen printing apparatus according to claim 1, wherein said printing conditions changed after said cleaning include an inclination of said squeegee when it contacts said mask. The print head is
Having a pressurizing part for pushing out the paste in the storage chamber to the mask,
2. The screen printing apparatus according to claim 1, wherein said printing conditions changed after said cleaning include a force applied by said pressure unit to said paste in said storage chamber. 6. The screen printing apparatus according to any one of claims 1 to 5, wherein said printing conditions changed after said cleaning include a movement speed at which said print head moves over said mask. 2. The screen printing apparatus according to claim 1, further comprising a printing condition learning unit that adjusts printing conditions based on the state of the paste printed on the substrate so that the state of the paste becomes a preset target state. . 8. The screen printing apparatus according to claim 7, wherein said printing condition learning unit adjusts said printing condition based on the state of said paste on a plurality of substrates having the same cleaning method executed immediately before. 8. The screen printing apparatus according to claim 7, wherein said printing condition learning section adjusts said printing condition based on a change in the state of said paste on a plurality of substrates printed after said cleaning. 10. The screen printing apparatus according to any one of claims 1 to 9, wherein said plurality of cleaning methods include at least one of a wet cleaning method using a solvent and a dry cleaning method not using a solvent. A screen printing method for printing a paste on a substrate,
a substrate contacting step of bringing the substrate into contact with a mask having a plurality of openings;
a printing step of forcing the paste into the plurality of openings by a print head;
a cleaning step of removing the paste adhering to the mask using one of a plurality of cleaning schemes;
after the cleaning step, a printing condition changing step of changing the printing conditions under which the print head prints the paste on the substrate, based on the number of times of application set for each of the cleaning methods performed. printing method. 12. The screen printing method according to claim 11, wherein said printing conditions to be changed in said printing condition changing step are set for each of said cleaning methods performed. 12. The screen printing method according to claim 11, wherein said printing conditions to be changed in said printing condition changing step include pressure with which said print head presses said paste into said plurality of openings in said printing step. The print head is
a squeegee that moves while being in contact with the upper surface of the mask to push the paste into the plurality of openings;
12. The screen printing method according to claim 11, wherein said printing conditions to be changed in said printing condition changing step include an inclination of said squeegee when said squeegee comes into contact with said mask in said printing step. The print head is
Having a pressurizing part that pushes out the paste in the storage chamber to the mask,
12. The screen printing method according to claim 11, wherein said printing conditions to be changed in said printing condition changing step include the force applied by said pressure unit to said paste in said storage chamber in said printing step. 16. The screen printing method according to any one of claims 11 to 15, wherein said printing conditions changed in said printing condition changing step include a moving speed at which said print head moves over said mask in said printing step. a printing inspection step of inspecting the state of the paste printed on the substrate;
12. The screen printing method according to claim 11, further comprising a printing condition learning step of adjusting printing conditions so that the state of the paste inspected in the printing inspection step becomes a preset target state. 18. The screen printing method according to claim 17, wherein the printing condition learning step adjusts the printing conditions based on the state of the paste on a plurality of substrates having the same cleaning method performed in the cleaning step. 18. The screen printing method according to claim 17, wherein said printing condition learning step adjusts said printing conditions based on a change in the state of said paste on a plurality of substrates printed after said cleaning step. 20. The screen printing method according to any one of claims 11 to 19, wherein said plurality of cleaning methods include at least one of a wet cleaning method using a solvent and a dry cleaning method not using a solvent.

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