JP2015039877A - Solder printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solder printer which monitors viscosity of cream solder on a mask.SOLUTION: A solder printer includes: a mask placed on an object to be printed; a squeegee for printing cream solder into the mask; a motor for moving the squeegee along the surface of the mask to which cream solder is supplied; motor control means which adjusts an output torque of the motor on the basis of a deviation between an actual speed and a target speed of the squeegee; and viscosity determination means which determines quality of viscosity of cream solder on the mask.

Description

  The technique disclosed here relates to a technique for printing solder, and more particularly, to a technique for printing cream solder using a mask and a squeegee (so-called screen printing).

  Patent Document 1 discloses a solder printer. This solder printing machine includes a mask disposed on a circuit board and a squeegee that imprints cream solder onto the mask, and moves the squeegee along the surface of the mask to which the cream solder is supplied, thereby applying a cream to the substrate. Print the solder. Such a printing method using a mask and a squeegee is generally called screen printing.

  In screen printing, if the viscosity of the cream solder is not appropriate, printing failure tends to occur. However, the viscosity of cream solder changes with time and also changes with temperature. Therefore, in the solder printer of Patent Document 1, a mechanism for measuring the viscosity of the cream solder on the mask is provided in the vicinity of the squeegee in order to monitor the viscosity of the cream solder on the mask.

JP 2004-249673 A

  In the conventional technique described above, it is necessary to provide a mechanism for measuring the viscosity of cream solder in the vicinity of the squeegee, which may lead to complication of the apparatus. For this reason, the present specification provides a technique capable of monitoring the viscosity of cream solder on a mask without requiring such a mechanism.

  The technology disclosed in this specification focuses on the output torque of the motor that moves the squeegee. When the squeegee moves along the surface of the mask, a resistance force corresponding to the viscosity of the cream solder acts on the squeegee. For example, when the cream solder has a high viscosity, the resistance force received by the squeegee increases, and as a result, the output torque of the motor that moves the squeegee increases. On the other hand, when the cream solder has a low viscosity, the resistance force received by the squeegee is also reduced, and as a result, the output torque of the motor that moves the squeegee is reduced. Thus, the output torque of the motor that moves the squeegee changes according to the viscosity of the cream solder on the mask. Therefore, whether the viscosity of the cream solder is good or not can be determined by monitoring the output torque of the motor (or the index corresponding thereto).

  The viscosity of cream solder has a speed dependency, and even with the same cream solder, the resistance to the squeegee increases as the moving speed of the squeegee increases. In order to eliminate the influence of the moving speed of the squeegee, it is preferable to control the operation of the motor so that the moving speed of the squeegee becomes a predetermined target speed. Alternatively, the quality of the cream solder viscosity may be determined by further considering not only the motor output torque (or the corresponding index) but also the moving speed of the squeegee (that is, the rotational speed of the motor).

  According to one aspect of the present technology, a solder printer that prints cream solder on a substrate is provided. This solder printing machine includes a mask placed on a substrate, a squeegee that imprints cream solder onto the mask, a motor that moves the squeegee along the surface of the mask supplied with cream solder, the actual speed and target of the squeegee Motor control means for adjusting the output torque of the motor based on the deviation from the speed, and viscosity determination means for judging the quality of the cream solder on the mask based on the output torque of the motor or a corresponding index. Prepare.

  According to the solder printer described above, the viscosity of the cream solder on the mask can be monitored without providing a mechanism for measuring the viscosity of the cream solder in the vicinity of the squeegee.

The figure which shows the mechanical structure of the solder printer of an Example. The block diagram which shows a part of electrical structure of the solder printer of an Example. The block diagram which shows the functional structure of a motor controller. The block diagram which shows the functional structure of a main controller. The flowchart which shows the process which a viscosity determination part performs. The figure which shows the tolerance | permissible_range regarding the command value T of the output torque of a servomotor. The figure which shows the example which corrects the above-mentioned tolerance | permissible_range according to the target speed of a squeegee.

  In one embodiment of the present technology, it is preferable that the viscosity determination unit obtains an output torque command value determined by the motor control unit as an index corresponding to the output torque of the motor. According to such a configuration, it is not always necessary to provide a torque sensor for detecting the output torque of the motor or a current sensor for detecting the current value of the motor.

  However, as another embodiment, the solder printer is a sensor for measuring the output torque of the motor or an index corresponding thereto, such as a torque sensor that measures the output torque of the motor or a current sensor that measures the current value of the motor. May be provided. In this case, the viscosity determination means can determine whether the viscosity of the cream solder is good or bad using the detection value of the sensors.

  In one embodiment of the present technology, it is preferable that the viscosity determination unit determines that the viscosity of the cream solder is defective when the output torque of the motor or the corresponding index is not within a predetermined allowable range. The predetermined allowable range herein may be a range having only one of an upper limit and a lower limit, or may be a range having both an upper limit and a lower limit.

  In one embodiment of the present technology, it is preferable that the viscosity determination unit corrects the above-described allowable range in accordance with at least one of the target speed of the squeegee and the remaining amount of cream solder existing on the mask. This is because the resistance received by the squeegee varies depending on the moving speed of the squeegee and the remaining amount of cream solder existing on the mask.

  In one embodiment of the present technology, the viscosity determination unit is configured to determine the viscosity of the cream solder based on the output torque of the motor or a corresponding index during a period from when the squeegee starts moving until it reaches the stencil part of the mask. It is preferable to judge pass / fail. According to such a configuration, it is possible to determine whether or not the viscosity of the cream solder is good before the cream solder is actually printed on the printing material, thereby preventing a printing defect from occurring.

  In one embodiment of the present technology, it is preferable that the solder printer further includes a notification unit that notifies a determination result of the viscosity determination unit to the outside. Here, the notification means may display the determination result to the operator, or may transmit the determination result to an apparatus such as a management computer.

  In an embodiment of the present technology, it is preferable that the solder printer further includes a countermeasure execution unit that executes a predetermined countermeasure operation according to a determination result by the viscosity determination unit. Examples of the countermeasure action include kneading cream solder, adding or replacing cream solder, adjusting the contact pressure (so-called printing pressure) of the squeegee to the mask, changing the plate separation condition (speed profile), and moving the squeegee. The conditions (number of divisions of the operation block and its speed), presence / absence of reciprocal printing operation, heating or cooling of the cream solder are included.

  With reference to the drawings, a solder printing apparatus 10 (hereinafter, simply referred to as a printing apparatus) of an embodiment will be described. The printing apparatus 10 is an apparatus that prints cream solder 4 on a circuit board 2 that is a substrate. Usually, the printing apparatus 10 is provided together with the electronic component mounting apparatus, and the circuit board 2 on which the printing apparatus 10 has printed the cream solder 4 is sent to the electronic component mounting apparatus. The electronic component mounting apparatus mounts a plurality of electronic components on a circuit board on which cream solder is printed.

  As shown in FIG. 1, the printing apparatus 10 includes a mask 20, a squeegee unit 30, and a squeegee moving device 40.

  The mask 20 is a plate-like member and has one or a plurality of openings 24 corresponding to the print pattern. The mask 20 is disposed on the circuit board 2 that is a substrate to be printed. The mask 20 generally has a stencil part 26 in which the above-described opening 24 is formed and is disposed immediately above the circuit board 2, and a peripheral part 28 that extends outside the stencil part 26. The specific material and structure of the mask 20 are not particularly limited. Although it is an example, the mask 20 of a present Example is a metal mask formed with the metal material.

  The squeegee unit 30 includes two squeegees 32 and a squeegee lifting device 34 for moving each squeegee 32 forward and backward with respect to the mask 20. The squeegee 32 is a member that imprints the cream solder 4 onto the mask 20 (more precisely, the opening 24 of the mask 20) by sliding on the surface 22 of the mask 20. The specific material and structure of the squeegee 32 are not particularly limited. Although it is an example, the squeegee 32 of the present embodiment is made of polyurethane. Moreover, although the squeegee unit 30 of a present Example is provided with the two squeegees 32 according to a moving direction, as another embodiment, the squeegee unit 30 may be provided with the single or three or more squeegees 32. .

  The squeegee lifting device 34 is a device for moving each squeegee 32 forward and backward with respect to the mask 20. In the squeegee unit 30, one squeegee 32 to be used is brought into contact with the surface 22 of the mask 20 by the squeegee lifting device 34, and the other unused squeegee 32 is separated from the surface 22 of the mask 20. Further, the squeegee unit 30 can adjust the contact pressure (so-called printing pressure) of the squeegee 32 against the mask 20 by the squeegee lifting device 34.

  The squeegee moving device 40 is a device that moves the squeegee unit 30 relative to the mask 20. The squeegee moving device 40 can reciprocate the squeegee unit 30 along a direction parallel to the surface 22 of the mask 20. As an example, the squeegee moving device 40 includes a guide rail 42, a feed screw 44, and a servo motor 46. The guide rail 42 extends parallel to the surface 22 of the mask 20 and supports the squeegee unit 30 so as to be slidable. The servo motor 46 is a motor that moves the squeegee unit 30, and is connected to the squeegee unit 30 via a feed screw 44. That is, the servo motor 46 moves the squeegee unit 30 along the guide rail 42 by rotating the feed screw 44. The servo motor 46 may be another type of motor capable of feedback control, such as a stepping motor.

  FIG. 2 is a block diagram partially showing an electrical configuration of the printing apparatus 10. As shown in FIG. 2, the printing apparatus 10 includes an encoder 48, a main controller 50, a motor controller 60, and a display 70 in addition to the servo motor 46 described above. The encoder 48 is a sensor for detecting the rotational position of the servo motor 46, and its output signal θ is input to the motor controller 60. The display 70 displays various information to the operator based on instructions from the main controller 50.

  The main controller 50 is configured using a computer device, and controls the overall operation of the printing apparatus 10. For example, the main controller 50 instructs the target speed Vt of the squeegee 32 to the motor controller 60. The motor controller 60 controls the operation of the servo motor 46 based on the instructed target speed Vt. Specifically, the motor controller 60 controls the current I flowing through the servo motor 46 based on the output signal θ of the encoder 48 so that the actual speed of the squeegee 32 becomes equal to the target speed Vt. Here, the speed such as the actual speed or the target speed of the squeegee 32 is a speed when the squeegee 32 slides on the surface 22 of the mask 20 and is equal to the moving speed of the squeegee unit 30 by the squeegee moving device 40.

  FIG. 3 is a block diagram showing a configuration of the motor controller 60. FIG. 3 shows an example, and the configuration of the motor controller 60 is not limited. As shown in FIG. 3, the motor controller 60 includes a comparison unit 61, a target torque determination unit 62, a driver controller 63, a motor driver 64, and a speed calculation unit 65.

  The speed calculation unit 65 calculates the actual speed Va of the squeegee 32 using the output signal θ of the encoder 48. The comparison unit 61 acquires the target speed Vt and the actual speed Va, and outputs the deviation to the target torque determination unit 62. The target torque determination unit 62 determines a command value T (hereinafter referred to as torque command value T) related to the output torque of the servo motor 46 based on the deviation between the target speed Vt and the actual speed Va. The determined torque command value T is taught to the driver controller 63. The driver controller 63 outputs a drive signal G to the motor driver 64 based on the taught torque command value T. The motor driver 64 operates based on the drive signal G from the motor driver 64. As a result, the current I flowing through the servomotor 46 is adjusted so that the output torque of the servomotor 46 becomes equal to the torque command value T. As shown in FIGS. 2 and 3, the torque command value T determined by the target torque determination unit 62 is also taught to the main controller 50.

  FIG. 4 is a block diagram partially showing the configuration of the main controller 50. As shown in FIG. 4, the main controller 50 includes a print control unit 52, a viscosity determination unit 54, a countermeasure determination unit 56, and a display control unit 58. The print control unit 52 controls the operation of each unit of the printing apparatus 10 and controls, for example, the servo motor 46 and the squeegee lifting device 34. The print control unit 52 also determines the target speed Vt of the squeegee 32 described above.

  The viscosity determination unit 54 determines the quality of the viscosity of the cream solder 4 on the mask 20 based on the torque command value T determined by the motor controller 60. When the squeegee 32 moves along the surface 22 of the mask 20, a resistance force according to the viscosity of the cream solder 4 acts on the squeegee 32. Therefore, the torque required for the servo motor 46 also changes according to the viscosity of the cream solder 4. Therefore, whether the viscosity of the cream solder 4 on the mask 20 is good or not can be determined based on the torque command value T determined by the motor controller 60.

  The countermeasure determining unit 56 determines a countermeasure operation corresponding to the determination result based on the determination result by the viscosity determining unit 54. Therefore, the countermeasure determining unit 56 stores a table that describes the determination result and the countermeasure action in association with each other. One or a plurality of arbitrary countermeasure actions can be described in the table. Possible countermeasure actions include, for example, kneading cream solder 4, adding or replacing cream solder 4, adjusting printing pressure, changing target speed of squeegee 32, heating cream solder 4, cooling cream solder 4, and the like. It is done. The countermeasure action determined by the countermeasure determining unit 56 is taught to the display control unit 58 and the print control unit 52. The display control unit 58 executes a process of displaying the countermeasure operation determined by the countermeasure determination unit 56 on the display 70 together with the determination result by the viscosity determination unit 54. Among the countermeasure operations determined by the countermeasure determination unit 56, the print control unit 52 performs the printing apparatus 10 such as kneading the cream solder 4, adding or replacing the cream solder 4, adjusting the printing pressure, and changing the target speed of the squeegee 32. Execute what you can do.

  FIG. 5 is a flowchart showing processing executed by the viscosity determination unit 54 to determine whether the viscosity of the cream solder 4 is good or bad. Hereinafter, with reference to the flowchart shown in FIG. 5, the process which the viscosity determination part 54 performs is demonstrated. FIG. 5 shows an example, and does not limit the processing executed by the viscosity determination unit 54.

  As shown in FIG. 5, when the printing apparatus 10 prints the first circuit board 2 of the production lot (YES in S12), the viscosity determination unit 54 performs a process of determining an allowable range related to the torque command value T. Execute (S12 to S18). First, the viscosity determination unit 54 controls the torque command determined by the motor controller 60 while the motor controller 60 controls the servo motor 46 and the squeegee 32 slides on the surface 22 of the mask 20 (that is, during the printing operation). The value T is acquired (S14). At this time, the viscosity determination unit 54 may acquire the torque command value T in at least a part of the period from when the squeegee 32 starts moving to when it ends. Although an example, the viscosity determination unit 54 according to the present embodiment acquires the torque command value T in a period from when the squeegee 32 starts to move until it reaches the stencil portion 26 of the mask 20.

  Next, the viscosity determination unit 54 calculates an average value Tm of the time-dependent data of the torque command value T acquired during the printing operation (S16). When the first circuit board 2 of the production lot is printed, it is immediately after so-called setup change, so that the viscosity of the cream solder 4 is usually adjusted to an appropriate level. Therefore, the average value Tm calculated here is a value corresponding to the appropriate viscosity of the cream solder 4, and can be used as a reference in the subsequent process for determining the quality of the viscosity.

  Next, the viscosity determination unit 54 determines an allowable range related to the torque command value T based on the calculated average value Tm (S18). As an example, as shown in FIG. 6, the viscosity determination unit 54 of the present embodiment includes an upper limit value T1 obtained by adding a predetermined value dT to the average value Tm, and a lower limit value T2 obtained by subtracting the predetermined value dT from the average value Tm. And the range from the upper limit value T1 to the lower limit value T2 is set as the allowable range. As another embodiment, the viscosity determination unit 54 may determine only one of the upper limit value T1 and the lower limit value T2. In this case, since the viscosity of the cream solder 4 tends to increase with time, it is preferable to determine at least the upper limit value T1. The determined allowable ranges (upper limit value T1 and lower limit value T2) are stored in the memory of the main controller 50.

  When the printing apparatus 10 shifts to printing of the second and subsequent circuit boards 2 (NO in S12), the viscosity determination unit 54 uses the previously determined allowable range (upper limit value T1 and lower limit value T2) to apply cream solder. 4 is started (S20 to S32). First, the viscosity determination unit 54 acquires the torque command value T determined by the motor controller 60 during the printing operation, similarly to step S14 described above (S20). That is, the viscosity determination unit 54 acquires the torque command value T during a period from when the squeegee 32 starts moving until it reaches the stencil portion 26 of the mask 20. Next, the viscosity determination unit 54 calculates an average value of the time-dependent data of the torque command value T acquired during the printing operation (S22). Hereinafter, the average value is referred to as a torque command value T.

  Next, when the torque command value T falls below the upper limit value T1 (YES in S24) and the torque command value T exceeds the lower limit value T2 (YES in S26), the viscosity determination unit 54 has a normal viscosity of the cream solder 4 (S30). On the other hand, when the torque command value T exceeds the upper limit value T1 (NO in S24), the viscosity determination unit 54 determines that the viscosity of the cream solder 4 is excessive (S28), and the torque command value T reaches the lower limit value T2. When below (NO in S26), it is determined that the viscosity of the cream solder 4 is insufficient (S32).

  As described above, the printing apparatus 10 according to the present embodiment can print the cream solder 4 while determining whether the viscosity of the cream solder 4 on the mask 20 is good or bad. Therefore, even when the viscosity of the cream solder 4 changes with time, it is possible to prevent printing defects from occurring. Furthermore, when the viscosity of the cream solder 4 is determined to be defective, the printing apparatus 10 can notify the operator of the determination result and the countermeasure action, and can also execute the countermeasure action itself.

  The printing apparatus 10 of the present embodiment can determine whether the viscosity of the cream solder 4 is good or not based on the torque command value T determined by the motor controller 60. As described above, when the index determined by the motor controller 60 is used, a sensor for detecting the output torque of the servo motor 46 or the index corresponding thereto is not required, and the configuration of the printing apparatus 10 can be simplified. it can.

  The printing apparatus 10 according to the present embodiment acquires the torque command value T determined by the motor controller 60 during the period from when the squeegee 32 starts moving until it reaches the stencil portion 26 of the mask 20, and based on the torque command value T, the cream The quality of the viscosity of the solder 4 is determined. With such a configuration, before the cream solder 4 is actually printed on the circuit board 2, it is possible to determine whether the cream solder 4 has a good viscosity or not to prevent printing defects.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

  For example, the printing apparatus 10 according to the present embodiment determines whether the viscosity of the cream solder 4 is good or not based on the torque command value T determined by the motor controller 60. However, the printing apparatus 10 replaces the torque command value T with another index corresponding to the output torque of the servo motor 46 (for example, a current value flowing through the servo motor 46 or a command value related to the current value), or the servo motor 46. May determine whether the viscosity of the cream solder 4 is good or not based on the torque currently being output. In this case, the printing apparatus 10 may further include a sensor that detects the index or torque.

  For example, the printing apparatus 10 according to the present embodiment determines the allowable range related to the torque command value T by itself when printing the first circuit board 2 in the production lot (see FIG. 5). However, as another embodiment, the printing apparatus 10 may be configured to previously teach and store an allowable range related to the torque command value T from the outside.

  The allowable range related to the torque command value T (or other index) is preferably corrected according to the target speed Vt of the squeegee 32 as shown in FIG. This is because the resistance received by the squeegee 32 changes according to the moving speed of the squeegee 32. From the same viewpoint, it is also preferable to correct the permissible range according to the remaining amount of the cream solder 4 existing on the mask 20, for example. In this case, the remaining amount of the cream solder 4 can be detected by a sensor or the like, or can be estimated from the number of printed circuit boards 2.

  Further, the allowable range related to the torque command value T (or other index) may be corrected accordingly when the cream solder type or manufacturer is different. It is also effective to correct the permissible range according to the material of the squeegee. These corrections may be automatically performed by the printing apparatus 10 or may be performed by a user or an operator of the printing apparatus 10.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2: Circuit board 4: Cream solder 10: Solder printer 20: Mask 26: Mask stencil part 32: Squeegee 40: Squeegee moving device 46: Servo motor 48: Encoder 50: Main controller 52: Print controller 54: Viscosity determination Unit 56: Countermeasure determination unit 58: Display control unit 60: Motor controller 62: Target torque determination unit 70: Display

Claims (7)

A solder printing machine for printing cream solder on a substrate,
A mask placed on the substrate;
A squeegee that imprints cream solder on the mask;
A motor that moves the squeegee along the surface of the mask supplied with the cream solder;
Motor control means for adjusting the output torque of the motor based on the deviation between the actual speed of the squeegee and the target speed;
Based on the output torque of the motor or an index corresponding thereto, viscosity determination means for determining whether the viscosity of the cream solder on the mask is good,
Solder printer equipped with.   The solder printing machine according to claim 1, wherein the viscosity determination unit acquires a command value of an output torque determined by the motor control unit as an index corresponding to the output torque of the motor.   3. The solder printing machine according to claim 1, wherein the viscosity determining unit determines that the viscosity of the cream solder is defective when an output torque of the motor or an index corresponding thereto is not within a predetermined allowable range.   4. The solder printer according to claim 3, wherein the viscosity determination unit corrects the allowable range according to at least one of a target speed of the squeegee and a remaining amount of cream solder existing on a surface of the mask. .   The viscosity determination means determines whether the viscosity of the cream solder is good or not based on an output torque of the motor or an index corresponding thereto in a period from when the squeegee starts moving until it reaches the stencil part of the mask, The solder printing machine as described in any one of Claim 1 to 4.   The solder printer according to any one of claims 1 to 5, further comprising an informing unit that informs the determination result by the viscosity determining unit to the outside.   The solder printer according to any one of claims 1 to 6, further comprising a countermeasure execution unit that executes a predetermined countermeasure operation in accordance with a determination result by the viscosity determination unit.

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