Calculation device

Abstract

Select an appropriate cleaning interval for your mask. [Solution] A calculation device that calculates the printing speed of the squeegee according to the cleaning interval, which is performed after printing the viscous material on N substrates, based on the cycle time when printing a viscous material on a substrate by sliding a squeegee on the upper surface of a mask in which through holes are formed, according to each of the multiple cleaning intervals with different N values, identifies a printing speed that is less than or equal to the maximum printing speed of the squeegee allowed by the printing apparatus that prints a viscous material on a substrate using a squeegee, and selects a cleaning interval based on the N value corresponding to the printing speed less than or equal to the identified maximum printing speed.

Description

Technical Field

[0006] , , ,

[0001] The present invention relates to an arithmetic device for calculating a cleaning interval for cleaning a mask.

Background Art

[0002] A printing machine that prints a viscous body on a substrate by sliding a squeegee on the upper surface of a mask having through holes is described in the following patent document.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] This specification aims to appropriately calculate the cleaning interval for cleaning a mask.

Means for Solving the Problems

[0005] In order to solve the above problems, this specification calculates the printing speed of the squeegee corresponding to the cleaning interval for cleaning the mask every time a viscous body is printed on N substrates based on the cycle time when printing the viscous body on the substrate by sliding the squeegee on the upper surface of the mask having through holes, for each of a plurality of the cleaning intervals with different N values, specifies a printing speed that is equal to or lower than the maximum printing speed of the squeegee allowed in a printing apparatus for printing a viscous body on a substrate using the squeegee, and discloses an arithmetic device that selects the cleaning interval based on the N value corresponding to the printing speed equal to or lower than the specified maximum printing speed.

Effects of the Invention

[0007] [Figure 1] This is a side view showing a printing press. [Figure 2] This is a plan view showing a printing press. [Figure 3] This is a perspective view showing the cleaning mechanism. [Figure 4] This is a cross-sectional view showing the cleaning mechanism. [Figure 5] Control device branch. [Figure 6] This graph shows the relationship between printing speed and print quality. [Figure 7] This graph shows the relationship between printing pressure and print quality. [Figure 8] This graph shows the relationship between printing speed and printing pressure. [Figure 9] This graph shows the relationship between squeegee angle and print quality. [Figure 10] This graph shows the relationship between ink release speed and print quality. [Figure 11] This diagram shows a flowchart for calculating the printing speed. [Figure 12] This diagram shows the distance traveled by the cleaning mechanism during the cleaning operation. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the figures, as embodiments for carrying out the present invention.

[0009] Figures 1 and 2 show the printing press 10. The printing press 10 is a machine used to print solder paste onto circuit boards. The printing press 10 includes a transport device 20, a mask holding device 22, a cleaning device 23, a squeegee device 24, a solder supply device 26, and a control device (see Figure 5) 28. Figure 1 shows the printing press 10 from a side view, and Figure 2 shows the printing press 10 from a top view.

[0010] The transport device 20 includes a conveyor device 30 and a substrate lifting device 32. The conveyor device 30 includes a pair of conveyor belts 34 and an electromagnetic motor (see Figure 5) 36 that rotates the conveyor belts 34. The direction in which the conveyor belts 34 extend is called the X direction, the direction perpendicular to the X direction is called the Y direction, and the direction perpendicular to both the X and Y directions is called the Z direction. The circuit board 38 is supported by the pair of conveyor belts 34 and transported in the X direction by the electromagnetic motor 36. The substrate lifting device 32 is positioned between the pair of conveyor belts 34 and supports the circuit board 38, which is supported by the pair of conveyor belts 34, from the bottom surface of the circuit board 38 via support pins 40, and lifts and lowers it at a predetermined position.

[0011] The mask holding device 22 is for fixedly holding the mask 50. The mask 50 is made of a metal sheet, such as stainless steel, and has multiple through holes (not shown) formed therein. The mask holding device 22 has a mask support base 52 disposed above the conveying device 20 and a mask holding mechanism 54 disposed on the upper surface of the mask support base 52. An opening (not shown) smaller than the outer edge of the mask 50 is formed in the center of the mask support base 52, and the mask 50 is placed on the mask support base 52 so as to cover this opening. The mask 50 placed on the mask support base 52 is then fixedly held by the mask holding mechanism 54. The mask holding mechanism 54 has an adjustment device 56 for adjusting the position of the held mask 50 in the X and Y directions, as well as for adjusting the rotation angle around a vertical line with the center of the mask as the axis.

[0012] Furthermore, the opening formed in the mask support base 52 is larger than the circuit board 38. The circuit board 38, which has been transported to a predetermined position by the transport device 20, is raised by the board lifting device 32 and comes into close contact with the lower surface of the mask 50 held by the mask holding device 22. The circuit board 38, which is in close contact with the lower surface of the mask 50, is then lowered by the board lifting device 32 and moves away from the lower surface of the mask 50.

[0013] The cleaning device 23 also includes a sliding device 60 and a cleaning mechanism 62. The sliding device 60 includes a pair of slide rails 66 and a slider 68. The pair of slide rails 66 are arranged parallel to each other in the vertical direction between the transport device 20 and the mask holding device 22 and extend in the Y direction. The slider 68 is slidably held by the pair of slide rails 66 and slides in the Y direction by the operation of an electromagnetic motor (see Figure 5) 70. The slide rails 66 do not overlap with the substrate lifting device 32 of the transport device 20 in the vertical direction, and as the slider 68 moves from above the substrate lifting device 32, the circuit board 38 is raised by the substrate lifting device 32 without coming into contact with the cleaning device 23.

[0014] Furthermore, as shown in Figures 3 and 4, the cleaning mechanism 62 includes a casing 70, a pair of winding shafts 71 and 72, a cleaning head 73, a suction device (see Figure 5) 74, and a spray device (see Figure 5) 76. The casing 70 is generally box-shaped and is fixed to the upper surface of the slider 68 in an orientation extending in the X direction. The length dimension of the casing 70 in the X direction is longer than the length dimension of the circuit board 38 in the X direction. The pair of winding shafts 71 and 72 extend in the X direction and are positioned opposite each other in the Y direction. It is disposed inside the ring 70 and is rotatably held about the axis by the casing 70. One of the pair of winding shafts 71 and 72, the cleaning sheet 77 is wound around the winding shaft 71, and the edge of the cleaning sheet 77 wound around the winding shaft 71 is wound around the other winding shaft 72 of the pair of winding shafts 71 and 72. Thereby, the cleaning sheet 77 is spanned between the pair of winding shafts 71 and 72. Further, the other winding shaft 72 of the pair of winding shafts 71 and 72 rotates about the axis by the operation of the electromagnetic motor 78. Thereby, the cleaning sheet 77 wound around the winding shaft 71 is wound around the winding shaft 72 by the operation of the electromagnetic motor 78. Incidentally, the length dimension of the cleaning sheet 77 in the X direction is substantially the same as the length dimension of the circuit board 38 in the X direction.

[0015] Further, the cleaning head 73 is generally in the shape of a rectangular parallelepiped bar and is disposed in a posture extending in the X direction between the pair of winding shafts 71 and 72. Incidentally, the length dimension of the cleaning head 73 in the X direction is slightly larger than the length dimension of the cleaning sheet 77 in the X direction. Further, the cleaning head 73 moves up and down between a standby position (solid line in FIG. 4) and a cleaning position (dotted line in FIG. 4) by the operation of the lifting device 79. Thereby, when the cleaning head 73 rises to the cleaning position, the cleaning sheet 77 spanned between the pair of winding shafts 71 and 72 is lifted above the upper end of the casing 70 by the cleaning head 73. On the other hand, when the cleaning head 73 descends to the standby position, the cleaning sheet 77 spanned between the pair of winding shafts 71 and 72 drops to the position of the upper end of the casing 70. Further, the suction device 74 is built in the cleaning head 73 and sucks air from the upper surface of the cleaning head 73. Further, the spraying device 76 is a device that sprays a solvent onto the cleaning sheet 77 spanned between the pair of winding shafts 71 and 72.

[0016] Further, as shown in FIGS. 1 and 2, the squeegee device 24 includes a squeegee moving device 80, a pair of squeegees 82, 84, and a squeegee lifting device 86. The squeegee moving device 80 includes a pair of slide rails 88 and a slider 90. The pair of slide rails 88 are disposed parallel to each other and extending in the Y direction above the mask holding device 22. The slider 90 is slidably attached to the pair of slide rails 88 and slides in the Y direction by the operation of an electromagnetic motor (see FIG. 5) 92. Each of the pair of squeegees 82, 84 is generally plate-shaped and formed of a flexible material. The pair of squeegees 82, 84 face each other and are disposed so as to extend in the X direction, and are held by the squeegee lifting device 86 below the slider 90. The squeegee lifting device 86 individually raises and lowers the pair of squeegees 82, 84.

[0017] Also, the solder supply device 26 is a device that supplies cream solder, and a discharge port 96 for discharging cream solder is formed on the lower surface of the solder supply device 26. The solder supply device 26 is fixed to a substantially central portion on the side surface of the slider 90 in the Y direction. Thereby, the solder supply device 26 moves to an arbitrary position in the Y direction by the operation of the squeegee moving device 80.

[0018] As shown in FIG. 5, the control device 28 includes a controller 100 and a plurality of drive circuits 102. The plurality of drive circuits 102 are connected to the electromagnetic motors 36, 70, 78, 92, the substrate lifting device 32, the adjustment device 56, the suction device 74, the spraying device 76, the squeegee lifting device 86, and the solder supply device 26. The controller 100 includes a CPU, a ROM, a RAM, etc., and is mainly a computer, and is connected to the plurality of drive circuits 102. Thereby, the operations of the transfer device 20, the squeegee device 24, etc. are controlled by the controller 100. Also, an information processing device 110 is connected to the controller 100. The information processing device 110 is used when calculating the moving speed of the squeegees 82, 84, that is, the printing speed, which will be described in detail later.

[0019] In the printing press 10, the circuit board 38 is transported to a predetermined position by the configuration described above and raised by the board lifting device 32, so that it comes into close contact with the lower surface of the mask 50 held by the mask holding device 22. The mask 50 has through holes (not shown) formed in accordance with the patterns of pads, etc. on the circuit board 38. Then, when solder paste is applied to the mask 50, the solder paste is printed onto the circuit board 38 through the through holes in the mask 50.

[0020] Specifically, the circuit board 38 is transported to the printing press 10 by the conveyor device 30 and moved to a predetermined position. At this time, the slider 68 of the cleaning device 23 is retracted from above the board lifting device 32. Then, the circuit board 38 is raised by the operation of the board lifting device 32. As a result, the circuit board 38 comes into close contact with the lower surface of the mask 50. Next, solder paste is supplied to the upper surface of the mask 50 by the solder supply device 26. Subsequently, one of the pair of squeegees 82, 84 is lowered by the squeegee lifting device 86, and the tip of the lowered squeegee comes into contact with the upper surface of the mask 50. Then, the squeegee is moved in the Y direction by the squeegee moving device 80, and the solder paste is scraped off by the squeegee. At this time, the solder paste fills the inside of the through-holes in the mask 50 and is printed onto the circuit board 38. Next, once the solder paste is printed onto the circuit board 38, the circuit board 38 is lowered by the operation of the board lifting device 32. This causes the circuit board 38 with the printed solder paste to separate from the mask 50. In other words, the so-called stencil separation process of the circuit board 38 is performed. Then, as the circuit board 38 lowers and is placed on the conveyor belt 34 of the conveyor device 30, it is discharged from the printing press 10 by the operation of the conveyor device 30. This completes the printing process on one circuit board 38.

[0021] Furthermore, in the printing press 10, the mask 50 is cleaned each time a predetermined number of circuit boards 38 are printed with solder paste. Specifically, once the printing of solder paste onto the predetermined number of circuit boards 38 is complete, the slider 68 of the cleaning device 23 moves below the opening of the mask support base 52. Then, the cleaning head 73 in the cleaning mechanism 62 of the cleaning device 23 rises to the cleaning position. As a result, the cleaning sheet 77, which is stretched between a pair of winding shafts 71 and 72, is lifted by the cleaning head 73 and enters the opening of the mask support base 52, making close contact with the underside of the mask 50. Then, as the slider 68 of the cleaning device 23 slides in the Y direction, the underside of the mask 50 is wiped by the cleaning sheet 77 that is in close contact with its underside. This cleans the underside of the mask 50.

[0022] The mask 50 can be cleaned using three methods: dry wiping, solvent cleaning (hereinafter referred to as "wet cleaning"), and suction cleaning (hereinafter referred to as "suction cleaning"). Any of these multiple cleaning methods can be used. Specifically, dry wiping is performed according to the procedure described above, in which the underside of the mask 50 is wiped with a dry cleaning sheet 77. In wet cleaning, solvent is sprayed onto the cleaning sheet 77 by the spraying device 76 before the cleaning head 73 rises. As the cleaning head 73 rises, the solvent-soaked cleaning sheet 77 comes into close contact with the underside of the mask 50, and as the slider 68 slides, the underside of the mask 50 is wiped with the solvent-soaked cleaning sheet 77. In suction cleaning, the suction device 74 is activated before the cleaning head 73 rises, or after the cleaning head 73 rises and comes into close contact with the underside of the mask 50. Then, as the slider 68 slides, the underside of the mask 50 is wiped by the cleaning sheet 77. At this time, air is drawn in from the top of the cleaning head 73, and through the cleaning sheet 77 which is in close contact with the underside of the mask 50, the underside of the mask 50 is cleaned. Air is drawn in. This allows the cleaning sheet 77 to wipe the underside of the mask 50 while simultaneously drawing air into it. In this suction cleaning process, no solvent is sprayed onto the cleaning sheet 77; the underside of the mask 50 is wiped with the dry cleaning sheet 77.

[0023] In this way, the printing press 10 prints solder paste onto the circuit board using squeegees 82 and 84, and the mask 50 is cleaned each time a predetermined number of circuit boards 38 are printed with solder paste. For this reason, it is necessary to set the printing conditions for the solder paste and the cleaning conditions for the mask. Here, the printing conditions for the solder paste consist of several conditions such as the squeegee's movement speed, the squeegee's angle, the squeegee's printing pressure, and the speed at which the circuit board is removed from the mask after the solder paste is printed (stencil release speed). These multiple conditions are not independent of each other but are related. In other words, for example, if the printing speed is changed, the printing pressure must also be changed, otherwise residual solder paste may remain on the mask, potentially degrading the printing quality of the solder paste on the circuit board. For this reason, in conventional methods, skilled workers set the printing conditions based on the amount of solder paste transferred, the transfer shape, and the inspection results of the solder paste printing state. As mentioned above, multiple conditions such as printing speed and printing pressure are related, so skilled workers would relatively adjust these multiple conditions based on the amount of solder paste transferred, the transfer shape, and the inspection results of the solder paste printing condition. However, in order to confirm the printing conditions adjusted by skilled workers, solder paste printing is performed on the circuit board as preparation according to those conditions, but if the printing conditions are not appropriate and the printing quality is poor, the circuit board is discarded, which increases production costs. In addition, since only skilled workers can relatively adjust multiple conditions such as printing speed and printing pressure, there are problems in securing and training skilled workers.

[0024] For this reason, one possible method is to statistically analyze the printing results to estimate the printing conditions, but obtaining the necessary printing results for analysis would take an enormous amount of time. Another possible method is to print solder paste on multiple circuit boards according to multiple printing conditions and estimate the optimal printing conditions from the inspection results. However, this would require actually printing solder paste on the circuit boards, resulting in a lot of wasted circuit boards. Alternatively, if the printing speed is limited to three types (low, standard, and high) and the printing pressure is limited to three types (low, standard, and high), and these printing conditions are combined to perform the printing process on the circuit boards, the analysis of the printing results would not take much time, and the number of wasted circuit boards could be reduced. However, if the setting conditions such as printing speed are limited to about three types, a skilled person would ultimately be required to fine-tune the setting conditions. In light of these considerations, simply inputting the cycle time, circuit board size, squeegee angle, squeegee type, and mask cleaning settings into the information processing device 110 will allow the information processing device 110 to calculate the optimal printing conditions such as printing speed and printing pressure.

[0025] More specifically, the slower the printing speed, the more effectively the solder paste can be filled into the through-holes of the mask 50. As shown in Figure 6, the slower the printing speed, the better the printing quality of the solder paste on the circuit board. Therefore, considering printing quality, a slower printing speed is preferable. However, considering cycle time, a faster printing speed is preferable. Therefore, if a cycle time is set in advance, it is preferable to set the slowest printing speed within the range that satisfies the set cycle time. Also, the higher the printing pressure, the cleaner the solder paste can be scraped off. As shown in Figure 7, the higher the printing pressure, the better the printing quality of the solder paste on the circuit board. Therefore, considering printing quality, a higher printing pressure is preferable. However, if the solder paste printing process is performed with high printing pressure, the load on the mask 50 increases, making the mask 50 more susceptible to damage. Therefore, considering this, a lower printing pressure is preferable. Therefore, it is preferable to set the lowest printing pressure at which the solder paste can be scraped off. In other words, by setting the lowest printing pressure at which the solder paste can be scraped off, the printing quality is compromised to some extent, while the slowest printing speed within the range that satisfies the cycle time is preferable. By setting the printing speed, print quality is improved and guaranteed. Therefore, the lowest printing pressure required to scrape the solder paste and the printing speed are proportional, as shown in Figure 8. In other words, the relationship between the lowest printing pressure F required to scrape the solder paste and the printing speed v is given by the following linear equation. F = αv + β

[0026] Furthermore, a smaller squeegee angle allows the solder paste to be pressed downwards, and as shown in Figure 9, a smaller squeegee angle improves the printing quality of the solder paste on the circuit board. However, the squeegee angle is fixed by the printing press, and generally, around 60 degrees is considered optimal. However, the squeegee angle affects the slope (α) and intercept (β) in the linear equation showing the relationship between printing pressure F and printing speed v. For this reason, the slope (α) and intercept (β) corresponding to a given squeegee angle are set experimentally in advance. Note that the slope (α) and intercept (β) change not only depending on the squeegee angle but also on the type of squeegee, for example, a metal squeegee or a urethane squeegee. Therefore, the slope (α) and intercept (β) are set experimentally in advance according to the type of squeegee as well as the squeegee angle. This allows the printing pressure F and printing speed v to be set according to the squeegee angle and the type of squeegee.

[0027] Furthermore, the faster the stencil release speed, the easier it is to separate the circuit board from the mask while preventing deformation of the solder paste printed on the circuit board. As shown in Figure 10, faster stencil release speeds result in improved print quality. Therefore, considering print quality, a fast stencil release speed is preferable. Also, considering cycle time, a fast stencil release speed is preferable. For this reason, the stencil release speed is set to a value close to the fastest within the operable range of the board lifting device 32, which operates when separating the circuit board from the mask.

[0028] Based on these assumptions, the information processing device 110 calculates the optimal printing conditions, such as printing speed and printing pressure. Below, the process by which the information processing device 110 calculates the optimal printing conditions, such as printing speed and printing pressure, is explained in detail using the flowchart shown in Figure 11. First, the cycle time T, the size y of the circuit board, the squeegee angle θ, the type of squeegee, and the mask cleaning settings are input to the information processing device 110 (S10). The cycle time T is the time required to perform the solder paste printing process on one circuit board, and is the time from when the circuit board is loaded into the printing press until it is unloaded from the printing press. The size y of the circuit board is the length dimension in the Y direction of the circuit board. The squeegee angle θ is selected from 50°, 55°, 60°, or 65°, and the type of squeegee is selected from either metal or urethane. In addition, the cleaning settings are configured to determine whether or not to use suction, whether or not to use solvent, and whether or not to save cleaning paper.

[0029] Then, once the cycle time T, circuit board size y, squeegee angle θ, squeegee type, and mask cleaning settings have been entered, the cleaning time tc is calculated based on the cleaning settings (S12). Specifically, if "no suction" and "no solvent" are set in the cleaning settings, dry wiping cleaning is performed for a distance y' corresponding to the circuit board size y. In other words, with the dry cleaning sheet 77 in contact with the bottom surface of the mask, the cleaning mechanism 62 moves in one direction in the Y direction for a distance y' corresponding to the circuit board size y. When the cleaning mechanism 62 moves in the Y direction with the cleaning sheet 77 in contact with the bottom surface of the mask, it needs to move a distance y' which is the size y of the circuit board 38 plus the distance A corresponding to the Y-direction dimension A of the cleaning mechanism 62, as shown in Figure 12. For this reason, the distance y' corresponding to the circuit board size y is calculated according to the following formula. y'=y+A

[0030] Thus, once the distance y' corresponding to the circuit board size y is calculated, the cleaning time tc, when no suction and no solvent are set, is calculated according to the following formula. tc = (y' / vc) + cleaning time The movement speed of the cleaning mechanism 62, i.e., the cleaning speed vc, is set in advance. The cleaning associated time is the total time required for the operations necessary for cleaning, such as the time to move the cleaning mechanism 62 to the cleaning start position, the time to move the cleaning mechanism 62 to the retracted position after cleaning is completed, the time to raise and lower the cleaning head 73, the time to apply the solvent, and the time to wind up the cleaning sheet 77.

[0031] Furthermore, if the cleaning settings are configured to either "no suction" or "solvent enabled," dry cleaning is performed on the outward journey for a distance y' corresponding to the size y of the circuit board, followed by wet cleaning on the return journey for a distance y' corresponding to the size y of the circuit board. In other words, first, with the dry cleaning sheet 77 in contact with the underside of the mask, the cleaning mechanism 62 moves in one direction in the Y direction for a distance y' corresponding to the size y of the circuit board. Then, with the solvent-soaked cleaning sheet 77 in contact with the underside of the mask, the cleaning mechanism 62 moves in the other direction in the Y direction for a distance y' corresponding to the size y of the circuit board. Therefore, if the cleaning settings are configured to either "no suction" or "solvent enabled," the cleaning mechanism 62 moves back and forth for a distance y' corresponding to the size y of the circuit board. Also, if the cleaning settings are configured to either "suction enabled" or "no solvent," suction cleaning is performed on the outward journey for a distance y' corresponding to the size y of the circuit board, followed by dry cleaning on the return journey for a distance y' corresponding to the size y of the circuit board. In other words, first, the dry cleaning sheet 77 comes into contact with the underside of the mask, and with the suction device 74 activated, the cleaning mechanism 62 moves in one direction in the Y direction by a distance y' corresponding to the size y of the circuit board. Then, with the dry cleaning sheet 77 in contact with the underside of the mask, the cleaning mechanism 62 moves in the other direction in the Y direction by a distance y' corresponding to the size y of the circuit board. Therefore, even when suction is enabled and solvent is disabled in the cleaning settings, the cleaning mechanism 62 moves back and forth by a distance y' corresponding to the size y of the circuit board. For this reason, when suction is disabled and solvent is enabled, and when suction is enabled and solvent is disabled, the cleaning time tc is calculated according to the following formula. tc = (2y' / vc) + cleaning time

[0032] Furthermore, if the cleaning settings include suction and solvent, suction cleaning is performed on the forward path for a distance y' corresponding to the size y of the circuit board, wet cleaning is performed on the return path for a distance y' corresponding to the size y of the circuit board, and then dry wiping cleaning is performed on the forward path for a distance y' corresponding to the size y of the circuit board. In other words, first, a dry cleaning sheet 77 comes into contact with the underside of the mask, and with the suction device 74 activated, the cleaning mechanism 62 moves in one direction in the Y direction for a distance y' corresponding to the size y of the circuit board. Then, with the solvent-soaked cleaning sheet 77 in contact with the underside of the mask, the cleaning mechanism 62 moves in the other direction in the Y direction for a distance y' corresponding to the size y of the circuit board. After that, with the dry cleaning sheet 77 in contact with the underside of the mask, the cleaning mechanism 62 moves in one direction in the Y direction for a distance y' corresponding to the size y of the circuit board. For this reason, if the cleaning settings include suction and solvent, the cleaning mechanism 62 moves one and a half round trips over a distance y' corresponding to the size y of the circuit board. Therefore, if suction and solvent are selected, the cleaning time tc is calculated according to the following formula. tc = (3y' / vc) + cleaning time

[0033] Next, once the cleaning time tc is calculated, the time required to print the solder paste onto the circuit board using the squeegee (hereinafter referred to as "squeegeeing time") t is calculated according to the following formula (S14). t = T - (tc / N) - th - ts Here, the cycle time T is input in S10, and the cleaning time tc is calculated in S12. Also, th is the time required for the stencil release operation (hereinafter referred to as "stencil release time"), that is, the time required to separate the circuit board from the mask. The stencil release speed is set to a value close to the fastest within the operating range of the board lifting device 32 that operates when separating the circuit board from the mask, as described above. The distance the circuit board descends during the stencil release operation (hereinafter referred to as "stencil release distance") and the acceleration when the circuit board descends (hereinafter referred to as "stencil release acceleration") are also set in advance. Therefore, the stencil release time is calculated based on the stencil release speed, stencil release distance, and stencil release acceleration. Also, ts is the sum of the time required to load the circuit board into the printing press 10, transport it to the work position, and load it out of the printing press 10 from the work position, the time required to raise the circuit board, and the time required to dispense the solder paste onto the top surface of the mask. Since these times can be measured or estimated in advance, the sum of these times, ts, is predetermined. N is the interval at which the mask is cleaned, that is, the cleaning interval at which the mask is cleaned every time the viscous material is printed on N substrates. Once this cleaning interval N is determined, the squeegeeing time t can be calculated according to the above formula. Therefore, the cleaning interval N is set to 10 natural numbers from 1 to 10, and the squeegeeing time t is calculated according to the above formula for each of these 10 cleaning intervals N. In other words, 10 squeegeeing times t are calculated: squeegeeing time t when the cleaning interval N is 1 (N=1), squeegeeing time t when the cleaning interval N is 2 (N=2), ... squeegeeing time t when the cleaning interval N is 9 (N=9), squeegeeing time t when the cleaning interval N is 10 (N=10).

[0034] Thus, when the squeegee time t is calculated according to each of the 10 cleaning intervals N numbered from 1 to 10, the printing speed v is calculated according to the following formula based on each squeegee time t (S16). v=[(t / 2)-{(t4 / 4)-(s / a)}1 / 2]a Here, the squeegeeing time t is calculated in S14 according to each of the 10 cleaning intervals N. Also, s is the distance over which the solder paste is printed on the circuit board by the squeegee, i.e., the printing stroke, which is the size of the circuit board y plus the run-up distance α. The run-up distance α is set in advance. Also, a is the acceleration of the squeegee when the solder paste is printed on the circuit board by the squeegee, and is set in advance. Therefore, 10 printing speeds v are calculated according to the squeegeeing time t calculated according to each of the 10 cleaning intervals N. In other words, 10 printing speeds v are calculated: printing speed v when the cleaning interval N is 1 (N=1), printing speed v when the cleaning interval N is 2 (N=2), ... printing speed v when the cleaning interval N is 9 (N=9), and printing speed v when the cleaning interval N is 10 (N=10).

[0035] Next, the printing speed v is calculated according to each of the 10 cleaning intervals N numbered from 1 to 10, and based on each printing speed v, the printing pressure F is calculated according to the following formula (S18). F = αv + β Here, the slope (α) and intercept (β) are preset according to the squeegee angle θ and squeegee type, as described above. Therefore, the slope (α) and intercept (β) are determined based on the squeegee angle θ and squeegee type entered in S10. Then, according to the above formula for the determined slope (α) and intercept (β), 10 cleaning intervals from 1 to 10 are set. The printing pressure F is calculated according to each of N's values. In other words, ten different printing pressures F are calculated: printing pressure F when the cleaning interval N is 1 (N=1), printing pressure F when the cleaning interval N is 2 (N=2), ... printing pressure F when the cleaning interval N is 9 (N=9), and printing pressure F when the cleaning interval N is 10 (N=10).

[0036] Next, the printing pressure F is calculated according to each of the 10 cleaning intervals N from 1 to 10, and it is determined in S10 whether or not cleaning paper is being saved in the cleaning settings entered (S20). If the cleaning setting is set not to save cleaning paper (S20: NO), the printing speed v with the smallest cleaning interval N among the printing speeds that the printer 10 can operate at is selected (S22). Here, the fastest printing speed vMAX of the squeegee on the printer 10 is set in advance. Therefore, from the 10 printing speeds v calculated in S16, printing speeds less than or equal to the fastest printing speed vMAX are identified. This identifies the printing speeds that the printer 10 can operate at. Then, the printing speed v with the smallest cleaning interval N among the identified printing speeds is selected. Specifically, for example, if the following print speeds are identified as operational: print speed v(N=3), print speed v(N=4)...print speed v(N=9), and print speed v(N=10), then the print speed with the smallest cleaning interval N among them, i.e., print speed v(N=3), will be selected.

[0037] Furthermore, if a cleaning setting to conserve cleaning paper is entered (S20:YES), the printing speed v with the largest cleaning interval N among the print speeds that can be operated by the printer 10, which is less than or equal to the set limit value, is selected (S24). Here, the set limit value is set for each squeegee angle θ. Specifically, for example, the set limit value is set to 2 for a squeegee angle θ(50°) and also to 2 for a squeegee angle θ(55°). Also, the set limit value is set to 4 for a squeegee angle θ(60°) and to 6 for a squeegee angle θ(65°). Then, from the 10 printing speeds v calculated in S16, the printing speeds less than or equal to the fastest printing speed vMAX are identified. This identifies the print speeds that can be operated by the printer 10. Then, the printing speed v with the largest cleaning interval N among the print speeds that can be operated by the printer 10, which is less than or equal to the set limit value, is selected. Specifically, for example, if the available print speeds are specified as print speed v(N=3), print speed v(N=4)...print speed v(N=9), and print speed v(N=10), and the squeegee angle θ is 60°, then the cleaning interval N of the setting limit value of 4 or less is 3 or 4, so print speed v(N=4) is selected. Also, for example, if the available print speeds are specified as print speed v(N=3), print speed v(N=4)...print speed v(N=9), and print speed v(N=10), and the squeegee angle θ is 50°, then there is no cleaning interval N of the setting limit value of 2 or less. In such cases, an error screen is displayed on the display device (not shown). This is because the cycle time T entered in S10 is too short, the print speed calculated according to that cycle time T is too fast, and the cleaning interval corresponding to the available print speed exceeds the setting limit value. Therefore, an error screen displays a message indicating that the entered cycle time T is too short and that a longer cycle time T should be re-entered. When the error screen is displayed, the process returns to S10, and the operator re-enters the cycle time T, etc. This causes the processing from S10 onward to be re-executed.

[0038] Then, in S22 or S24, when a printing speed v is selected, the selected printing speed v, the cleaning interval N corresponding to that printing speed v, the printing pressure F corresponding to that printing speed v, the stencil release setting, and the cleaning operation are output from the information processing device 110 to the controller 100. The stencil release setting is the stencil release speed, stencil release distance, and stencil release acceleration used when calculating the stencil release time th in S14. The cleaning operation is dry wiping, wet cleaning, and suction cleaning, depending on the cleaning setting input in S10. This information indicates which of the following actions to perform. When the controller 100 receives the print speed v, cleaning interval N, print pressure F, stencil release setting, and cleaning operation, it performs the paste solder printing process and mask cleaning based on the received print speed v, cleaning interval N, print pressure F, stencil release setting, and cleaning operation.

[0039] Thus, by simply inputting the cycle time T, substrate size y, squeegee angle θ, squeegee type, and cleaning settings into the information processing device 110, the optimal printing conditions such as printing speed and pressure, as well as the cleaning interval according to whether or not cleaning paper is being saved, are automatically calculated. This solves the aforementioned problems such as securing and training skilled workers and the increase in production costs.

[0040] In the above embodiment, circuit board 38 is an example of a substrate. Mask 50 is an example of a mask. Squeegees 82 and 84 are examples of squeegees. Information processing device 110 is an example of an arithmetic device. Solder paste is an example of a viscous material. The fastest printing speed vMAX is an example of an allowable limit speed.

[0041] It should be noted that the present invention is not limited to the above embodiments, and can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Specifically, for example, in the above embodiment, the plate release speed is set to a value close to the fastest within the operable range of the substrate lifting device 32. However, depending on the type of viscous material, if the plate release speed is too fast, the quality may deteriorate. Therefore, it is possible to set it to any value depending on the type of viscous material.

[0042] Furthermore, in the above embodiment, if the cycle time T input to the information processing device 110 is too short, an error screen is displayed and the user is prompted to re-enter the cycle time T. However, a range of acceptable cycle times may be set on the cycle time T input screen. This can suppress the input of extremely short cycle times T.

[0043] Furthermore, in the above embodiment, for example, when the cleaning mechanism 62 performs dry wiping and wet cleaning, dry wiping is performed on the forward path, followed by wet cleaning on the return path. On the other hand, the cleaning mechanism 62 may only move while performing the cleaning operation on the forward path, and the return path may be simply movement without cleaning. That is, for example, the cleaning mechanism 62 moves from the front to the back of the printing press 10 while performing dry wiping (forward path). Next, the cleaning mechanism 62 moves away from the mask and moves from the back to the front of the printing press 10 (return path) (movement without cleaning operation). Subsequently, the cleaning mechanism 62 moves from the front to the back of the printing press 10 while performing wet cleaning (forward path). The cleaning time tc in this case is calculated according to the following formula. tc = (2y' / vc) + (y' / vi) + cleaning associated time Note that vi is the movement speed of the cleaning mechanism 62 during movement only, without any cleaning action, that is, the movement speed of the cleaning mechanism 62 on the return journey.

[0044] Furthermore, in the above embodiment, the printing speed v, printing pressure F, etc. are calculated in the information processing device 110, but the printing speed v, printing pressure F, etc. may also be calculated in the controller 100. In other words, the controller 100 may function as the calculation device of the present invention.

[0045] Furthermore, while solder paste is used as the viscous material in the above embodiment, various viscous materials can be used as long as they are printed onto the circuit board using a squeegee. [Explanation of symbols]

[0046] 38: Circuit board (board) 50: Mask 82: Squeegee 84: Squeegee 110: Information processing device (arithmetic unit)

Claims

1. Based on the cycle time when printing a viscous substance onto a substrate by sliding a squeegee across the upper surface of a mask with through-holes, the printing speed of the squeegee is calculated according to the cleaning interval, which is performed after printing the viscous substance onto N substrates, for each of the multiple cleaning intervals with different N values. Of the calculated printing speeds, a printing speed less than or equal to the maximum printing speed of the squeegee allowed by the printing apparatus for printing a viscous substance onto a substrate using the squeegee is identified. A calculation device that selects the cleaning interval based on an N value corresponding to a printing speed less than or equal to the specified maximum printing speed.

2. Determine whether or not cleaning paper is being saved. If it is determined that the aforementioned saving of cleaning paper will not be performed, the cleaning interval will be selected based on the smallest N value among the N values ​​corresponding to printing speeds less than or equal to the specified maximum printing speed. The calculation device according to claim 1, which, when it is determined that the cleaning paper should be saved, selects the cleaning interval based on the largest N value among the N values ​​corresponding to a printing speed less than or equal to the specified maximum printing speed, which is less than or equal to the setting limit value set for each angle of the squeegee.

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