Calculation device

Abstract

To properly compute pressure applied by a squeegee when a viscous body is printed on a substrate.SOLUTION: An arithmetic unit computes pressure applied by a squeegee on the basis of cycle time that is time required for performing printing processing to a single substrate with a viscous body and a substrate size that is a linear dimension of the substrate in a movement direction of a squeegee that prints the viscous body on the substrate trough a through-hole of a mask in the printing processing.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a computing device that calculates the printing pressure of a squeegee that prints a viscous material onto a substrate through through holes in a mask in a printing process. [Background technology]

[0002] The following patent documents describe a printing machine that prints a viscous material on a substrate by sliding a squeegee over the top surface of a mask having through holes formed therein. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-150073 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present specification is to appropriately calculate the printing pressure of a squeegee when a viscous material is printed on a substrate. [Means for solving the problem]

[0005] In order to solve the above problems, this specification provides a method for printing a viscous material onto a substrate, the method comprising: a cycle time, which is the time required to perform a printing process of a viscous material on one substrate; a substrate size, which is the length dimension of the substrate in the moving direction of a squeegee that prints the viscous material on the substrate through a through-hole in a mask during the printing process; , the angle of the squeegee, the type of the squeegee, and the mask cleaning settings. The present invention discloses a calculation device that calculates the printing pressure of the squeegee based on the above. [Effects of the Invention]

[0006] According to the present disclosure, the printing pressure of the squeegee when printing a viscous material on a substrate can be appropriately set. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a side view showing a printing press. [Figure 2] FIG. 1 is a plan view showing a printing press. [Figure 3] FIG. 2 is a perspective view showing a cleaning mechanism. [Figure 4] FIG. 2 is a cross-sectional view showing a cleaning mechanism. [Figure 5] FIG. 2 is a block diagram showing a control device. [Figure 6] 10 is a graph showing the relationship between printing speed and print quality. [Figure 7] 10 is a graph showing the relationship between printing pressure and print quality. [Figure 8] 10 is a graph showing the relationship between printing speed and printing pressure. [Figure 9] 10 is a graph showing the relationship between squeegee angle and print quality. [Figure 10] 10 is a graph showing the relationship between plate separation speed and print quality. [Figure 11] FIG. 10 is a flowchart showing a process for calculating a printing speed. [Figure 12] FIG. 4 is a diagram showing a moving distance of a cleaning mechanism during a cleaning operation. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings as modes for carrying out the present invention.

[0009] 1 and 2 show a printer 10. The printer 10 is a machine for printing cream solder on a circuit board. The printer 10 includes a conveying device 20, a mask holding device 22, and a cleaner. The printer 10 includes a cleaning device 23, a squeegee device 24, a solder supply device 26, and a control device (see FIG. 5) 28. Note that FIG. 1 is a diagram showing the printer 10 from a side perspective, and FIG. 2 is a diagram showing the printer 10 from an above perspective.

[0010] The transfer device 20 includes a conveyor device 30 and a board lifting device 32. The conveyor device 30 includes a pair of conveyor belts 34 and an electromagnetic motor (see FIG. 5) 36 that rotates the conveyor belts 34. The direction in which the conveyor belts 34 extend is referred to as the X direction, the direction horizontally perpendicular to the X direction is referred to as the Y direction, and the direction perpendicular to both the X and Y directions is referred to as the Z direction. A circuit board 38 is supported by the pair of conveyor belts 34 and is transported in the X direction by being driven by the electromagnetic motor 36. The board lifting device 32 is disposed between the pair of conveyor belts 34 and supports the circuit board 38 supported by the pair of conveyor belts 34 from the underside of the circuit board 38 via support pins 40, and lifts and lowers the circuit board 38 to a predetermined position.

[0011] The mask holding device 22 is used to securely hold the mask 50. The mask 50 is made of a metal, for example, a stainless steel sheet, and has a plurality of through-holes (not shown). The mask holding device 22 has a mask support table 52 disposed above the transport device 20 and a mask holding mechanism 54 disposed on the upper surface of the mask support table 52. An opening (not shown) smaller than the outer edge of the mask 50 is formed in the center of the mask support table 52, and the mask 50 is placed on the mask support table 52 so as to cover the opening. The mask 50 placed on the mask support table 52 is then securely held by the mask holding mechanism 54. The mask holding mechanism 54 has an adjustment device 56 that adjusts the position of the held mask 50 in the X and Y directions and adjusts the rotation angle around a vertical line centered on the center of the mask.

[0012] The opening formed in the mask support table 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 substrate 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 circuit board 38, which has been in close contact with the lower surface of the mask 50, is lowered by the substrate lifting device 32, so that it moves away from the lower surface of the mask 50.

[0013] The cleaning device 23 also has a slide device 60 and a cleaning mechanism 62. The slide device 60 includes a pair of slide rails 66 and a slider 68. The pair of slide rails 66 are disposed vertically between the transport device 20 and the mask holding device 22, extending parallel to each other and in the Y direction. The slider 68 is slidably held by the pair of slide rails 66, and slides in the Y direction by operation of an electromagnetic motor (see FIG. 5 ). 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 lifted by the substrate lifting device 32 without coming into contact with the cleaning device 23.

[0014] 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 FIG. 5) 74, and a spray device (see FIG. 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 of the casing 70 in the X direction is longer than the length of the circuit board 38 in the X direction. The pair of winding shafts 71 and 72 extend in the X direction and are disposed inside the casing 70 in an orientation facing each other in the Y direction, and are held by the casing 70 so as to be rotatable about their axes. A cleaning sheet 77 is wound around one winding shaft 71 of the pair of winding shafts 71 and 72, and the edge of the cleaning sheet 77 wound around the winding shaft 71 is , and is wound around the other winding shaft 72 of the pair of winding shafts 71, 72. As a result, the cleaning sheet 77 is stretched between the pair of winding shafts 71, 72. Furthermore, the other winding shaft 72 of the pair of winding shafts 71, 72 is rotated about its axis by operation of the electromagnetic motor 78. As a result, the cleaning sheet 77 wound around the winding shaft 71 is wound around the winding shaft 72 by operation of the electromagnetic motor 78. The length dimension of the cleaning sheet 77 in the X direction is approximately the same as the length dimension of the circuit board 38 in the X direction.

[0015] The cleaning head 73 has a generally rectangular rod shape and is disposed between the pair of winding shafts 71, 72, extending in the X direction. The length of the cleaning head 73 in the X direction is slightly longer than the length of the cleaning sheet 77 in the X direction. The cleaning head 73 is raised and lowered between a standby position (solid line in FIG. 4) and a cleaning position (dotted line in FIG. 4) by the operation of an elevator device 79. When the cleaning head 73 rises to the cleaning position, the cleaning sheet 77, which is stretched between the pair of winding shafts 71, 72, is lifted above the upper end of the casing 70 by the cleaning head 73. When the cleaning head 73 descends to the standby position, the cleaning sheet 77, which is stretched between the pair of winding shafts 71, 72, is lowered to the upper end of the casing 70. The suction device 74 is built into the cleaning head 73 and sucks air from the upper surface of the cleaning head 73. The spray device 76 is a device that sprays a solvent onto a cleaning sheet 77 that is stretched between a pair of winding shafts 71 and 72.

[0016] 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 above the mask holding device 22 so as to be parallel to each other and extend in the Y direction. 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 made 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 below the slider 90 by a squeegee lifting device 86. The squeegee lifting device 86 raises and lowers the pair of squeegees 82, 84 individually.

[0017] The solder supply device 26 is a device that supplies cream solder, and an outlet 96 for discharging the cream solder is formed on the underside of the solder supply device 26. The solder supply device 26 is fixed to approximately the center of the side surface in the Y direction of the slider 90. This allows the solder supply device 26 to move to any position in the Y direction by operating 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, and 92, the substrate lifting device 32, the adjusting 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, ROM, RAM, and the like, and is primarily a computer, and is connected to the plurality of drive circuits 102. This allows the controller 100 to control the operation of the conveying device 20, the squeegee device 24, and the like. The controller 100 is also connected to an information processing device 110. The information processing device 110, which will be described in detail later, is used to calculate the movement speed of the squeegees 82 and 84, i.e., the printing speed.

[0019] In the printing machine 10, the circuit board 38 is transported to a predetermined position by the above-described configuration, and is then raised by the board lifting device 32, so that the mask held by the mask holding device 22 is lifted. The mask 50 is tightly attached to the underside of the circuit board 38. The mask 50 has through holes (not shown) formed in accordance with the pattern of the pads and the like of the circuit board 38. Then, cream solder is applied to the mask 50, and the cream solder is printed on the circuit board 38 through the through holes in the mask 50.

[0020] Specifically, the circuit board 38 is carried into the printing press 10 by the conveyor device 30 and transported to a predetermined position. At this time, the slider 68 of the cleaning device 23 is retracted from above the board lifting device 32. The board lifting device 32 then operates to lift the circuit board 38, bringing the circuit board 38 into close contact with the lower surface of the mask 50. Next, the solder supply device 26 supplies cream solder to the upper surface of the mask 50. Next, one of the pair of squeegees 82, 84 is lowered by the squeegee lifting device 86, and the tip of the lowered squeegee contacts the upper surface of the mask 50. The squeegee is then moved in the Y direction by the squeegee moving device 80, and the cream solder is scraped off by the squeegee. At this time, the cream solder fills the through holes in the mask 50 and is printed on the circuit board 38. Next, once the solder paste has been printed on the circuit board 38, the board lifting device 32 is operated to lower the circuit board 38. This causes the circuit board 38 on which the solder paste has been printed to separate from the mask 50. In other words, the so-called plate separation operation of the circuit board 38 is performed. Then, once the circuit board 38 has been lowered and placed on the conveyor belt 34 of the conveyor device 30, the conveyor device 30 is operated to carry the circuit board 38 out of the printing machine 10. This completes the printing operation on one circuit board 38.

[0021] Furthermore, in the printing press 10, the mask 50 is cleaned every time cream solder is printed on a predetermined number of circuit boards 38. More specifically, when the printing of cream solder on a predetermined number of circuit boards 38 is completed, the slider 68 of the cleaning device 23 moves below the opening of the mask support base 52. Then, the cleaning head 73 of the cleaning mechanism 62 of the cleaning device 23 rises to the cleaning position. As a result, the cleaning sheet 77 stretched between the pair of winding shafts 71, 72 is lifted by the cleaning head 73, enters the opening of the mask support base 52, and comes into 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 in close contact with the underside. This cleans the underside of the mask 50.

[0022] The mask 50 can be cleaned by dry wiping, by using a solvent (hereinafter referred to as "wet cleaning"), or by using a suction device 74 (hereinafter referred to as "suction cleaning"). Any of these cleaning methods can be performed. Specifically, dry wiping is performed in the above-described procedure, in which the underside of the mask 50 is wiped with a dry cleaning sheet 77. In wet cleaning, before the cleaning head 73 is raised, the spray device 76 sprays a solvent onto the cleaning sheet 77. As the cleaning head 73 is raised, the cleaning sheet 77 soaked in the solvent comes into close contact with the underside of the mask 50, and the slider 68 slides, wiping the underside of the mask 50 with the cleaning sheet 77 soaked in the solvent. In suction cleaning, the suction device 74 is activated before the cleaning head 73 is raised or after the cleaning head 73 is raised 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 with the cleaning sheet 77. At this time, air is sucked from the upper surface of the cleaning head 73, and so air is sucked from the underside of the mask 50 through the cleaning sheet 77 that is in close contact with the underside of the mask 50. As a result, the underside of the mask 50 is wiped with the cleaning sheet 77 while being sucked. Note that in suction cleaning, no solvent is sprayed onto the cleaning sheet 77, and the mask 50 is wiped with the dry cleaning sheet 77. The underside is wiped clean.

[0023] In this way, in the printer 10, cream solder is printed on the circuit boards using the squeegees 82 and 84, and the mask 50 is cleaned every time a predetermined number of circuit boards 38 are printed with cream solder. Therefore, it is necessary to set cream solder printing conditions and mask cleaning conditions. Here, the cream solder printing conditions include multiple conditions, such as the squeegee movement speed, squeegee angle, squeegee printing pressure, and the speed at which the circuit board is separated from the mask after cream solder printing (mask separation speed). However, these multiple conditions are not independent of each other but are interrelated. For example, if the printing speed is changed without also changing the printing pressure, some of the cream solder may not be scraped off on the mask, which could degrade the quality of the cream solder print on the circuit board. For this reason, in conventional methods, skilled technicians set the printing conditions based on the amount and shape of the cream solder transferred, inspection results of the cream solder print status, etc. As mentioned above, since multiple conditions such as printing speed and printing pressure are related to each other, an expert adjusts the multiple conditions, such as printing speed and printing pressure, based on the amount and shape of the transferred solder paste, and the inspection results of the printed solder paste condition. However, in order to confirm the printing conditions adjusted by the expert, solder paste is printed on the circuit board according to those printing conditions as a preliminary step. If the printing conditions are inappropriate and the print quality is poor, the circuit board is discarded, which increases production costs. Furthermore, since only an expert can adjust the multiple conditions, such as printing speed and printing pressure, there are problems with securing and training experts.

[0024] For this reason, one possible method is to statistically analyze the printing results to estimate the printing conditions, but obtaining the printing results necessary for analysis takes a significant amount of time. Another possible method is to print solder paste on multiple circuit boards under multiple printing conditions and then estimate the optimal printing conditions from the inspection results. However, since the solder paste must actually be printed on the circuit boards, many circuit boards will be wasted. Furthermore, for example, by limiting the printing speed to three types (slow, standard, and high) and the printing pressure to three types (low, standard, and high), and then combining these printing conditions to print on the circuit boards, analyzing the printing results will not take much time and the number of wasted circuit boards can be reduced. However, limiting the setting conditions such as printing speed to around three types ultimately requires an experienced person to fine-tune the setting conditions. In light of this, by simply inputting the cycle time, circuit board size, squeegee angle, squeegee type, and mask cleaning settings into the information processing device 110, the information processing device 110 can calculate the optimal printing conditions, such as printing speed and printing pressure.

[0025] Specifically, the slower the printing speed, the more effectively the solder paste can be filled into the through holes in the mask 50. Therefore, as shown in FIG. 6, the slower the printing speed, the better the quality of the solder paste printed on the circuit board. Therefore, a slower printing speed is preferable when considering print quality. However, a faster printing speed is preferable when considering cycle time. Therefore, if the cycle time is preset, it is preferable to set the slowest printing speed within the range that satisfies the preset cycle time. Furthermore, since the higher the printing pressure, the more cleanly the solder paste can be scraped off, as shown in FIG. 7, the higher the printing pressure, the better the quality of the solder paste printed on the circuit board. Therefore, a high printing pressure is preferable when considering print quality. However, when the solder paste printing process is performed at a high printing pressure, the load on the mask 50 increases, making the mask 50 more susceptible to damage. Therefore, a low printing pressure is preferable. Therefore, it is preferable to set the lowest printing pressure possible that allows the solder paste to be scraped off. In other words, by setting the lowest printing pressure that allows the solder paste to be scraped off, the printing quality is compromised to some extent, while by setting the slowest printing speed within the range that satisfies the cycle time, the printing quality is improved and guaranteed. For this reason, the lowest printing pressure that allows the solder paste to be scraped off and the printing speed are proportional, as shown in Figure 8. In other words, the relationship between the lowest printing pressure F that allows the solder paste to be scraped off and the printing speed v is is the following linear equation: F=αv+β

[0026] Furthermore, the smaller the squeegee angle, the more downward the solder paste can be pressed. Therefore, as shown in Figure 9, the smaller the squeegee angle, the better the printing quality of the solder paste on the circuit board. However, the squeegee angle is a fixed value for each printing machine, and a value of around 60 degrees is generally considered optimal. However, the squeegee angle affects the slope (α) and intercept (β) in the linear equation that expresses the relationship between the printing pressure F and the printing speed v. Therefore, the slope (α) and intercept (β) corresponding to a given squeegee angle are determined in advance through experiments. Note that the slope (α) and intercept (β) vary not only depending on the squeegee angle but also on the type of squeegee, such as a metal squeegee or a urethane squeegee. Therefore, the slope (α) and intercept (β) are determined in advance through experiments according to not only the squeegee angle but also the type of squeegee. This allows the printing pressure F and printing speed v to be set according to the squeegee angle and type of squeegee.

[0027] Furthermore, the faster the stencil removal speed, the more the circuit board can be removed from the mask while preventing the cream solder printed on the circuit board from losing its shape, and therefore, as shown in FIG. 10, the faster the stencil removal speed, the better the print quality. Therefore, when considering print quality, a fast stencil removal speed is preferable. Also, when considering cycle time, a fast stencil removal speed is preferable. For this reason, the stencil removal speed is set to a value close to the fastest within the operable range of the board lifting device 32, which operates when removing the circuit board from the mask.

[0028] Based on these assumptions, the information processing device 110 calculates optimal printing conditions such as printing speed and printing pressure. The process of calculating optimal printing conditions such as printing speed and printing pressure in the information processing device 110 will be described in detail below using the flowchart shown in FIG. 11. First, the cycle time T, the circuit board size y, the squeegee angle θ, the squeegee type, and the mask cleaning settings are input to the information processing device 110 (S10). The cycle time T is the time required to print solder paste on one circuit board, and is the time from when the circuit board is loaded into the printer to when it is unloaded from the printer. The circuit board size y is the length of the circuit board in the Y direction. The squeegee angle θ is selected from 50°, 55°, 60°, and 65°, and the squeegee type is selected from metal and urethane. The cleaning settings include whether or not to use suction, whether or not to use solvent, and whether or not to save cleaning paper.

[0029] Then, once the input of the cycle time T, the size y of the circuit board, the squeegee angle θ, the squeegee type, and the mask cleaning settings is complete, the cleaning time tc is calculated based on the cleaning settings, etc. (S12). Specifically, if the cleaning settings are set to no suction and no solvent, dry wiping cleaning is performed for a distance y' corresponding to the size y of the circuit board. That is, 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 by a distance y' corresponding to the size y of the circuit board. Note that, when the cleaning mechanism 62 moves in the Y direction with the cleaning sheet 77 in contact with the underside of the mask, as shown in FIG. 12, it needs to move a distance y' obtained by adding a distance corresponding to the size y of the circuit board 38 to the dimension A of the cleaning mechanism 62 in the Y direction. Therefore, the distance y' corresponding to the size y of the circuit board is calculated according to the following formula: y'=y+A

[0030] In this way, when the distance y' corresponding to the size y of the circuit board 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 moving speed of the cleaning mechanism 62, i.e., the cleaning speed vc, is set in advance. The cleaning-related time is the total time required for operations required for cleaning, such as the time required to move the cleaning mechanism 62 to the cleaning start position, the time required to move the cleaning mechanism 62 to the retracted position after cleaning is completed, the time required to raise and lower the cleaning head 73, the time required to apply the solvent, and the time required to wind up the cleaning sheet 77.

[0031] Furthermore, when the cleaning settings are set to no suction and with solvent, dry wiping cleaning is performed on the outbound path for a distance y' corresponding to the size y of the circuit board, and then wet cleaning is performed on the return path for a distance y' corresponding to the size y of the circuit board. That is, 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, after that, 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, when the cleaning settings are set to no suction and with solvent, the cleaning mechanism 62 reciprocates for a distance y' corresponding to the size y of the circuit board. Furthermore, when the cleaning settings are set to with suction and without solvent, suction cleaning is performed on the outbound path for a distance y' corresponding to the size y of the circuit board, and then dry wiping cleaning is performed on the return path for a distance y' corresponding to the size y of the circuit board. That is, first, the dry cleaning sheet 77 contacts the underside of the mask, and with the suction device 74 activated, the cleaning mechanism 62 moves in one direction in the Y direction a distance y' corresponding to the size y of the circuit board. Then, after that, with the dry cleaning sheet 77 still in contact with the underside of the mask, the cleaning mechanism 62 moves in the other direction in the Y direction a distance y' corresponding to the size y of the circuit board. Therefore, even when the cleaning settings are set to include suction and no solvent, the cleaning mechanism 62 moves back and forth a distance y' corresponding to the size y of the circuit board. Therefore, when the settings are set to include no suction and solvent, and when the settings are set to include suction and no solvent, the cleaning time tc is calculated according to the following formula. tc = (2y' / vc) + cleaning time

[0032] Furthermore, when the cleaning settings include suction and solvent, suction cleaning is performed on the outbound 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 outbound path for a distance y' corresponding to the size y of the circuit board. That is, first, the dry cleaning sheet 77 contacts 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 the 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 the distance y' corresponding to the size y of the circuit board. Still further, 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 the distance y' corresponding to the size y of the circuit board. Therefore, when the cleaning settings include suction and solvent, the cleaning mechanism 62 makes one and a half reciprocating movements over the distance y' corresponding to the size y of the circuit board. Therefore, when the settings are made to use suction and solvent, 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 with the squeegee (hereinafter referred to as the "squeegeeing time") t is calculated using the following formula: Therefore, the calculation is performed (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. th is the time required for the stencil separation operation (hereinafter referred to as the "stencil separation time"), i.e., the time required to separate the circuit board from the mask. As described above, the stencil separation speed is set to a value close to the fastest value within the operable range of the board lifting device 32, which operates to separate the circuit board from the mask. The distance by which the circuit board descends during the stencil separation operation (hereinafter referred to as the "stencil separation distance") and the acceleration at which the circuit board descends (hereinafter referred to as the "stencil separation acceleration") are also set in advance. Therefore, the stencil separation time is calculated based on the stencil separation speed, stencil separation distance, and stencil separation acceleration. ts is the sum of the time required to transport the circuit board into the printing press 10, transport it to the work position, and transport it from the work position to the outside of the printing press 10, the time required to lift the circuit board, and the time required to dispense cream solder onto the upper surface of the mask. These times can be measured or estimated in advance, and the sum of these times, ts, is preset. Furthermore, N is the interval between mask cleanings, i.e., the cleaning interval at which the mask is cleaned every time a viscous material is printed on N substrates. Once this cleaning interval N is determined, the squeegee 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 squeegee time t is calculated according to the above formula for each of the 10 cleaning intervals N. That is, 10 squeegee times t are calculated: squeegee time t (N=1) when the cleaning interval N is 1, squeegee time t (N=2) when the cleaning interval N is 2, squeegee time t (N=9) when the cleaning interval N is 9, and squeegee time t (N=10) when the cleaning interval N is 10.

[0034] In this way, when the squeegee time t is calculated according to each of the 10 cleaning intervals N from 1 to 10, the printing speed v is calculated in accordance with 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 for each of the 10 cleaning intervals N. s is the distance the squeegee prints the solder paste on the circuit board, i.e., the printing stroke, and is the value obtained by adding the run-up distance α to the circuit board size y. The run-up distance α is preset. a is the acceleration of the squeegee when the squeegee prints the solder paste on the circuit board, and is also preset. Therefore, 10 printing speeds v are calculated according to the squeegeeing time t calculated for each of the 10 cleaning intervals N. That is, 10 printing speeds v are calculated: printing speed v (N=1) when the cleaning interval N is 1, printing speed v (N=2) when the cleaning interval N is 2, printing speed v (N=9) when the cleaning interval N is 9, and printing speed v (N=10) when the cleaning interval N is 10.

[0035] Next, when the printing speed v is calculated according to each of the 10 cleaning intervals N from 1 to 10, the printing pressure F is calculated based on each printing speed v in accordance with the following formula (S18). F=αv+β Here, the slope (α) and intercept (β) are set in advance according to the squeegee angle θ and the type of squeegee, as described above. Therefore, the slope (α) and intercept (β) are specified based on the squeegee angle θ and the type of squeegee input in S10. Then, according to the above formula for the specified slope (α) and intercept (β), the printing pressure F corresponding to each of the 10 cleaning intervals N from 1 to 10 is calculated. That is, the printing pressure F (N=1) when the cleaning interval N is 1, the printing pressure F (N=2) when the cleaning interval N is 2, the printing pressure F (N=9) when the cleaning interval N is 9, the printing pressure F (N=1) when the cleaning interval N is 10, and the printing pressure F (N=2) when the cleaning interval N is 10 are calculated. Ten printing pressures F (N=10) are calculated.

[0036] Next, once the printing pressure F is calculated for each of the ten cleaning intervals N from 1 to 10, it is determined whether or not cleaning paper is to be saved in the cleaning settings entered in S10 (S20). If a cleaning setting indicating that cleaning paper is not to be saved is entered (S20: NO), a printing speed v with the smallest cleaning interval N among the printing speeds operable by the printing press 10 is selected (S22). Here, the fastest squeegee printing speed vMAX in the printing press 10 is set in advance. Therefore, a printing speed equal to or lower than the fastest printing speed vMAX is identified from the ten printing speeds v calculated in S16. This identifies the printing speed operable by the printing press 10. Then, a printing speed v with the smallest cleaning interval N among the identified printing speeds is selected. Specifically, for example, if print speed v(N=3), print speed v(N=4), print speed v(N=9), print speed v(N=10) are identified as operable print speeds, the print speed with the smallest cleaning interval N among those print speeds, i.e., print speed v(N=3), is selected.

[0037] Furthermore, if a cleaning setting indicating that cleaning paper saving is to be performed has been input (S20: YES), a printing speed v having the largest cleaning interval N that is equal to or less than the set limit value among the printing speeds at which the printing press 10 is operable 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 set to 2 for a squeegee angle θ (55°). Furthermore, the set limit value is set to 4 for a squeegee angle θ (60°), and also set to 6 for a squeegee angle θ (65°). Then, a printing speed equal to or less than the fastest printing speed vMAX is identified from the 10 printing speeds v calculated in S16. This identifies a printing speed at which the printing press 10 is operable. Then, a printing speed v having the largest cleaning interval N that is equal to or less than the set limit value among the printing speeds at which the printing press 10 is operable is selected. Specifically, for example, if print speed v(N=3), print speed v(N=4), print speed v(N=9), and print speed v(N=10) are specified as operable print speeds, and the squeegee angle θ is 60°, the cleaning interval N below the set limit of 4 is either 3 or 4, so print speed v(N=4) is selected. Also, for example, if print speed v(N=3), print speed v(N=4), print speed v(N=9), and print speed v(N=10) are specified as operable print speeds, and the squeegee angle θ is 50°, there is no cleaning interval N below the set limit of 2. In such a case, an error screen is displayed on the display device (not shown). This is because the cycle time T entered in S10 is too short, and the print speed calculated according to that cycle time T is too fast, causing the cleaning interval corresponding to the operable print speed to exceed the set limit. Therefore, a message is displayed on the error screen stating that the input cycle time T is too short and that a cycle time T longer than the input cycle time T should be re-input. When the error screen is displayed, the process returns to S10, where the worker re-inputs the cycle time T, etc. This causes the process from S10 onwards to be executed again.

[0038] Then, when a printing speed v is selected in S22 or S24, the selected printing speed v, the cleaning interval N corresponding to the printing speed v, the printing pressure F corresponding to the 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 information indicating which of dry wiping cleaning, wet cleaning, and suction cleaning is to be performed according to the cleaning setting input in S10. Then, when the controller 100 receives the printing speed v, cleaning interval N, printing pressure F, stencil release setting, and cleaning operation, it performs the following based on the received printing speed v, cleaning interval N, printing pressure F, stencil release setting, and cleaning operation: A cream solder printing process and mask cleaning are performed.

[0039] In this way, simply by 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 speed, printing pressure, and other printing conditions, as well as the cleaning interval depending on whether or not cleaning paper is to be saved, can be automatically calculated. This solves the above-mentioned problems of securing and training skilled personnel and increasing production costs.

[0040] In the above embodiment, the circuit board 38 is an example of a board. The mask 50 is an example of a mask. The squeegees 82 and 84 are an example of a squeegee. The information processing device 110 is an example of a computing device. The cream solder is an example of a viscous material. The maximum printing speed vMAX is an example of an allowable limit speed.

[0041] The present invention is not limited to the above-described embodiment, and can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Specifically, for example, in the above-described embodiment, the plate detachment speed is set to a value close to the fastest within the operable range of the substrate lifting device 32, but since a plate detachment speed that is too fast may result in a decrease in quality depending on the type of viscous material, the speed can be set to any value depending on the type of viscous material, etc.

[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 to prompt the user to re-input the cycle time T, but a range of cycle times that can be input may be set on the input screen for the cycle time T. This makes it possible to prevent an extremely short cycle time T from being input.

[0043] Furthermore, in the above embodiment, for example, when the cleaning mechanism 62 performs dry wiping cleaning and wet cleaning, dry wiping cleaning is performed on the outbound path, and then wet cleaning is performed on the return path. On the other hand, the cleaning mechanism 62 may only move while performing the cleaning operation on the outbound path, and the return path may simply be a movement without a cleaning operation. That is, for example, the cleaning mechanism 62 moves from the front to the back of the printing press 10 while performing dry wiping cleaning (outbound path). Next, the cleaning mechanism 62 moves from the back to the front of the printing press 10, separating from the mask (return path) (movement without a cleaning operation). Next, the cleaning mechanism 62 moves from the front to the back of the printing press 10 while performing wet cleaning (outbound path). The cleaning time tc at this time is calculated according to the following formula. tc = (2y' / vc) + (y' / vi) + cleaning time Note that vi is the movement speed of the cleaning mechanism 62 when only movement is not accompanied by a cleaning operation, that is, the movement speed of the cleaning mechanism 62 on the return path.

[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, in the above embodiment, cream solder is used as the viscous material, but various viscous materials can be used as long as they can be printed on the circuit board by a squeegee. [Explanation of symbols]

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

Claims

1. A calculation device that calculates the printing pressure of the squeegee based on the cycle time, which is the time required to perform the viscous material printing process on one substrate, the substrate size, which is the length dimension of the substrate in the direction of movement of the squeegee that prints the viscous material on the substrate through the through holes in the mask during the printing process, the angle of the squeegee, the type of squeegee, and the cleaning settings of the mask.

2. 2. The computing device according to claim 1, wherein the computing device calculates a printing speed of the squeegee based on the cycle time, the substrate size, the squeegee angle, the squeegee type, and a cleaning setting of the mask, and calculates a printing pressure of the squeegee based on the calculated printing speed.

3. 3. The calculation device according to claim 2, wherein the squeegee printing pressure is calculated based on the printing speed using a linear equation that expresses that the squeegee printing pressure and the printing speed are proportional to each other.

4. 4. The calculation device according to claim 3, wherein the linear expression has a slope and an intercept that are set in accordance with the squeegee angle.

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