JP4840417B2 - Solder printing apparatus and solder printing method - Google Patents

Description

  The present invention relates to a solder printing apparatus and a solder printing method using a screen mask and a squeegee.

In screen printing, the upper surface of the substrate (the surface on which the solder is printed) is covered with a mask, and the cream solder is spread on the mask using a squeegee so that the solder is pushed into the pattern holes provided in the mask. This is a printing technique widely used in the field of mounting electronic components, in which solder is printed in a predetermined shape following the pattern hole on the upper surface of the substrate. The squeegee slides from one end of the mask to the other end while scraping off the solder on the mask to print the solder. Therefore, when printing is finished, a lump of solder is formed on the other end of the mask. The squeegee is composed of a pair of one that slides from one end to the other on the mask and one that slides from the other end to the other. By using a pair of squeegees alternately, the solder lump is masked. Solder is continuously printed on a plurality of substrates while being moved up. When the solder printing on one substrate is finished, the squeegee used for printing is lifted and separated from the mask, and the other squeegee is lowered and brought into contact with the mask. May follow and lift while attached to the squeegee. For this reason, the amount of solder remaining on the mask is reduced more than the amount actually printed on the substrate, the amount of solder necessary to print on the assumed number of substrates is insufficient, Problems with printing defects such as insufficient printing amount occurred. In order to grasp the follow-up of the solder to such a squeegee, there is a technique for detecting the adhesion state of the solder based on whether or not the reflected light is received by the solder using a reflective photoelectric sensor (see Patent Document 1).
JP 2000-263754 A

  When detecting the adhesion state of solder to the squeegee using an optical sensor such as a reflective photoelectric sensor, multiple optical sensors are required for wide squeegees depending on the detectable range. It is disadvantageous. In addition, depending on the position and shape of the solder, light may not be reflected at an assumed position. In this case, there is a disadvantage that the adhesion of solder cannot be detected.

  An object of the present invention is to provide a solder printing apparatus and a solder printing method that prevent the occurrence of printing defects by detecting the adhesion of solder to a squeegee without omission.

  The present invention includes, firstly, a cylinder mechanism that raises and lowers a squeegee with respect to a screen mask, means for supplying an upper pressure increase and a lower pressure decrease for raising and lowering the squeegee to the cylinder mechanism, and after solder printing Means for measuring a height at which the squeegee is raised when a predetermined upper pressure is supplied to the cylinder mechanism, and means for judging whether the squeegee is attached to the solder based on the height at which the squeegee is raised; Are configured as a solder printing apparatus. Since the rising height of the squeegee varies depending on the amount of the solder attached under a constant upward pressure, whether the solder is attached or not is determined based on the actual height of the increased squeegee.

Secondly, in the first configuration, the means for determining whether the squeegee is attached to the solder is good or bad when the squeegee is raised to a predetermined height within a predetermined time. It was set as the structure which judges. Since the squeegee ascending speed varies depending on the amount of solder adhesion under a certain upward pressure increase, the quality of the solder adhesion state is judged based on the time required for the squeegee to reach a predetermined height.

  Third, in the first configuration, the squeegee includes a means for storing a height at which the squeegee rises when a predetermined upper pressure is supplied to the cylinder mechanism in a state where no solder is attached to the squeegee. The means for judging whether or not the solder adhesion state is good is based on a result of comparison between the stored height and the measured height, and judges whether or not the solder adhesion state of the squeegee is good. The degree of solder adhesion can be determined by the difference between the height at which the squeegee to which no solder is attached rises and the actually measured height.

  Fourth, a step of printing solder on the substrate while applying a lower pressure drop for lowering the squeegee to the screen mask to the squeegee, and a step of applying a predetermined upper pressure increase for raising the squeegee after the solder printing to the squeegee And a step of determining the state of solder attachment to the squeegee based on the height at which the squeegee is raised when the predetermined upper pressure is applied.

  Since the quality of the solder adhesion state is determined based on the rising height of the squeegee that varies depending on the amount of solder adhesion, it is possible to detect the adhesion of the solder without being affected by the position and shape of the solder.

  Embodiments of the present invention will be described with reference to the accompanying drawings. 1, 2, and 3 are side views of a solder printing apparatus according to an embodiment of the present invention, FIG. 4 is a side view of a squeegee apparatus provided in the solder printing apparatus, and FIG. 5 is supplied to an air cylinder during solder printing. FIG. 6 is a side view showing the relationship between the pressure supplied to the air cylinder and the height of the squeegee, and FIG. 7 is a flowchart showing an operation example of the solder printing apparatus according to the embodiment of the present invention.

  First, the solder printing apparatus will be described. The solder printing apparatus 1 includes a board support device 2, a screen mask 3, a squeegee device 4, and an inspection device 5. The substrate support device 2 adjusts the height of the substrate 6 so that the clamp 7 that holds the substrate 6 with the printing surface facing upward horizontally and the printing surface of the substrate 6 and the upper surface of the clamp 7 are aligned on the same plane. A substrate height adjusting mechanism 8; a substrate lifting mechanism 9 that raises the substrate 6 during solder printing to bring the printed surface into close contact with the back surface of the screen mask 3, and lowers the substrate 6 away from the screen mask 3 when separating the plate; An X robot 10 and a Y robot 11 which are substrate horizontal movement mechanisms for moving the substrate 6 in the horizontal direction with respect to the screen mask 3 to align the substrate 6 and the screen mask 3 are configured.

  The screen mask 3 has a plurality of holes 12 penetrating the front and back surfaces, and has a structure in which cream-like solder 13 supplied on the front surface side is transferred and printed on the printing surface of the substrate 6 following the shape of the holes 12.

  The squeegee device 4 includes a pair of squeegees 14 and 15 and a squeegee lifting mechanism 16 that lifts and lowers the squeegees 14 and 15. As shown in FIG. 2, the squeegee 14 fills the holes 12 while sliding the surface of the screen mask 3 and moving the solder 13. The solder 13 filled in the hole 12 comes out of the hole 12 and follows the substrate 6 when the plate is released. As a result, the substrate 6 is in a state in which the solder 13 following the position and shape of the hole 12 is printed on the printed surface.

The squeegees 14 and 15 have directions in opposite directions. The squeegee 14 that has come into contact with the screen mask 3 in FIG. 2 moves up and separates from the screen mask 3 after moving the solder 13 as shown in FIG. When the board 6 on which the solder is printed by the squeegee 14 is unloaded and a new board 6 is loaded, the squeegee 15 performs solder printing while moving the solder 13 on the screen mask 3 in the opposite direction.

  The inspection apparatus 5 includes cameras 17 and 18 that capture images in the vertical direction. After the printing is completed, the image is moved between the screen mask 3 and the substrate 6 to image the screen mask 3 and the substrate 6, and the clogging of the screen mask 3 and the solder printing state are inspected by image analysis. The inspection result is notified to the operator by a display device or a warning device (not shown).

  The conveyance rail 19 is connected to each device in the pre-process and the post-process of the solder printing apparatus 1, and carries the substrate 6 to be printed from the pre-process and carries the printed substrate 6 to the post-process. .

  Next, the squeegee device 4 will be described with reference to FIG. The squeegee lifting device 16 is provided with two of the same configuration corresponding to each of the squeegees 14 and 15. Here, the squeegee 14 will be described as an example.

  A squeegee lifting mechanism 16 that lifts and lowers the squeegee 14 relative to the machine frame 20 includes a ball screw mechanism and a cylinder mechanism. The ball screw mechanism has a function of setting the height of the squeegee 14, and the cylinder mechanism has a function of pushing the squeegee 14 downward further from the height set by the ball screw mechanism.

  The ball screw mechanism includes a ball screw 21 that is rotatably attached to the machine frame 20 around a vertical axis, a nut 22 that is screwed with the ball screw 21, a motor 23 that provides rotational driving to the ball screw 21, and a ball screw 21. And pulleys 24 and 25 attached to the rotation shaft of the motor 23, and a belt 26 tuned to the pulleys 24 and 25. A cylinder mechanism is attached to the nut 22, and the cylinder mechanism itself moves up and down by driving a ball screw mechanism.

  The cylinder mechanism includes an air cylinder 31 that extends and contracts the rod 30 downward. A moving plate 32 is attached to the tip of the rod 30. A squeegee lock claw 33 is attached to the moving plate 32. The squeegee lock claw 33 can detachably fix the squeegee 14. The squeegee lock claw 33 is attached to the moving plate 32 via a bearing 34, and the squeegee 14 attached to the squeegee lock claw 33 can follow the inclination of the mask plate 3 while changing the angle with respect to the moving plate 32. it can.

  The two shafts 35 and 36 arranged with the ball screw 21 sandwiched between them are connected to the moving plate 32 at the lower end, and are inserted into brackets 37 and 38 attached to the machine frame 20 so as to be slidable in the vertical direction. Yes. These shafts 35 and 36 increase the attachment rigidity of the squeegee 14 and regulate the elevation of the squeegee 14 in the vertical direction, and prevent the squeegee 14 from rotating as the ball screw 21 rotates.

The air cylinder 31 is provided with two air supply ports 41 and 42. Air that has been regulated by a regulator (not shown) is constantly supplied from one air supply port 41, and an upward pressure increase is caused in the air cylinder 31 to raise the squeegee 14. The air adjusted by the regulator 43 is supplied from the other air supply port 42. The air supplied from the air supply port 42 is for lowering the squeegee 14, and if the pressure generated by the air is weaker than the constantly increasing pressure, the air cylinder 31 still has the rising pressure. The squeegee 14 is raised because the squeegee 14 is maintained. On the other hand, if the pressure is higher than the constantly increasing pressure, the air cylinder 31 has a lower pressure drop that lowers the squeegee 14, and the squeegee 14 is lowered.

  The squeegee device 4 includes a dog 44 attached to the moving plate 32 and a height detection sensor 45 attached to the machine frame 20 as a detection mechanism for detecting the height of the squeegee 14. The height detection sensor 45 detects the height of the squeegee 14 by detecting the dog 44 that moves up and down with the moving plate 32.

  Next, the pressure generated by the air cylinder will be described with reference to FIG. The solder printing apparatus 1 performs printing while pressing the squeegee 14 against the surface of the screen mask 3 during solder printing and applying pressure (printing pressure) to the solder 13. This printing pressure is applied by driving the cylinder mechanism. That is, the height of the squeegee 14 relative to the screen mask 3 is adjusted by the ball screw mechanism, and the printing pressure is applied by further lowering the squeegee 14 by the cylinder mechanism. The printing pressure is adjusted by the regulator 43.

  During solder printing, a lower pressure drop (printing pressure p1) for lowering the squeegee 14 is supplied to the air cylinder 31. The lowered squeegee 14 is pressed against the screen mask 3 and fills the holes 12 while applying the printing pressure p 1 to the solder 13.

  When the plate is released, the balance pressure p2 is supplied to the air cylinder 31. The balance pressure p2 is a pressure that maintains the squeegee 14 in a state in which neither the squeegee 14 is raised nor lowered. In this state, the squeegee 14 is only in light contact with the screen mask 3.

  When the plate separation is completed, the detection pressure p3 is supplied to the air cylinder 31. The detection pressure p3 is a rising pressure that raises the squeegee 14. The squeegee 14 can be raised to a predetermined height within a predetermined time as long as a small amount of solder adheres to the squeegee 14. If the squeegee 14 has an increased total weight due to a large amount of solder adhering to the squeegee 14, the squeegee 14 has a rising pressure that makes it impossible to raise it to a predetermined height within a predetermined time.

  FIG. 6A shows the height of the squeegee 14 when the balance pressure p2 is supplied. Since the balance pressure p <b> 2 is supplied to the air cylinder, the lower end of the squeegee is in light contact with the screen mask 3. The squeegee 14 is in contact with the solder 13 to which the printing pressure p1 is applied during printing. FIGS. 6B and 6C show the height of the squeegee 14 when the detection pressure p3 is supplied. Ascending pressure acts on the squeegee 14 by the start of supply of the detection pressure p3, but when the solder 13 pressed by the action of the printing pressure p1 adheres to the squeegee 14, it is shown in FIG. In this way, a part of the solder 13 may be lifted while adhering to the squeegee 14. If the amount of attached solder is small, the influence of the weight increase of the squeegee 14 is small, so the squeegee 14 rises smoothly and the dog 44 reaches the detection height of the height detection sensor 45 within a predetermined time.

  On the other hand, the total weight of the squeegee 14 is greatly increased due to the adhesion of a large amount of solder, or the solder 13 is fixed to the squeegee 14 in a lump as shown in FIG. When the increase is inhibited, the dog 44 cannot reach the detection height within a predetermined time.

  The solder printing apparatus 1 determines whether the soldering state of the squeegee 14 is good or not based on whether or not the height detection sensor 45 detects the dog 44 during the elapse of a predetermined time after the supply of the detection pressure p3 is started. If the height detection sensor 45 detects the dog 44 within a predetermined time, the solder adhesion state is determined to be normal, and if not detected, it is determined to be abnormal.

Next, a solder printing operation performed by the solder printing apparatus 1 will be described with reference to FIG. The solder printing apparatus 1 prints solder on the printed surface of the substrate 6 that has been carried in, and then separates the substrate 6 and the screen mask 3 (ST1). When the plate separation is completed, the detection pressure p3 is supplied to the air cylinder 31 (ST2). The elapsed time from immediately after the supply of the detection pressure p3 is started is confirmed (ST3). If the squeegee 14 rises to a predetermined height before a predetermined time (set here to 2 seconds) and the height detection sensor 45 detects the dog 44 (ST4), printing is continued (ST5). Since it was confirmed that the squeegee 14 was lifted, it was confirmed that a small amount of solder adhered to the squeegee 14, that is, a sufficient amount of solder remained on the screen mask 3. This is because there is no problem with the amount of solder even if the process is continued.

  On the other hand, if the height detection sensor 45 does not detect the dog 44 even after 2 seconds from the start of the supply of the detection pressure p3 and the rising of the squeegee 14 cannot be confirmed, the printing is interrupted and the squeegee is stopped. An abnormal warning for prompting cleaning 14 or refilling solder is issued (ST6). The fact that the rise of the squeegee 14 cannot be confirmed means that a large amount of solder adheres to the squeegee 14 and the amount of solder remaining on the screen mask 3 is insufficient, or the solder loses fluidity and is fixed as a lump. This is because the printing is considered to be unsuitable for printing, and if printing is continued as it is, there may be a problem of defective printing.

  The height detection sensor 45 is arranged as a point on the moving path of the dog 44 that rises as the squeegee 14 rises, and the rise of the squeegee 14 is confirmed when the dog 44 passes the detection height of the height detection sensor 45. Alternatively, the height of the squeegee 14 may be measured by arranging the squeegee 14 in a continuous line along the movement path of the dog 44. In this case, the height that rises when the squeegee 14 in a state where no solder is attached is supplied with the detection pressure p3 is stored in advance, and the solder attachment state is determined by comparing with the actually raised height. To do. It is possible to determine the degree of solder adhesion according to the degree of difference between the stored height and the actually measured height.

  The present invention can be used in the mounting field in which solder is printed using a screen mask and a squeegee.

Side view of a solder printing apparatus according to an embodiment of the present invention Side view of a solder printing apparatus according to an embodiment of the present invention Side view of a solder printing apparatus according to an embodiment of the present invention Side view of the squeegee device provided in the solder printer Graph showing pressure supplied to air cylinder Side view showing the relationship between the pressure supplied to the air cylinder and the height of the squeegee The flowchart which shows the example of printing operation of the solder printer of embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solder printer 3 Screen mask 6 Board | substrate 14, 15 Squeegee 31 Air cylinder 43 Regulator 44 Dog 45 Height detection sensor

Claims (4)

A cylinder mechanism that raises and lowers the squeegee relative to the screen mask;
Means for supplying the cylinder mechanism with upper and lower pressures for raising and lowering the squeegee;
Means for measuring the height at which the squeegee is raised when a predetermined upper pressure is supplied to the cylinder mechanism after solder printing;
Means for determining whether the soldering state of the squeegee is attached based on the height of the squeegee;
A solder printing apparatus comprising:   The means for judging whether or not the squeegee solder is attached is good or bad when the squeegee is raised to a predetermined height within a predetermined time to determine whether the squeegee solder is attached or not. The solder printing apparatus according to 1. Means for storing a height at which the squeegee rises when a predetermined upper pressure is supplied to the cylinder mechanism in a state where no solder is attached to the squeegee;
The means for judging whether the soldering state of the squeegee is in good condition determines whether the soldering state of the squeegee is in good condition based on a comparison result between the stored height and the measured height. The solder printing apparatus according to claim 1. A step of printing solder on the substrate while acting on the squeegee a lower pressure drop that lowers the squeegee with respect to the screen mask;
A step of applying a predetermined upward pressure to the squeegee to raise the squeegee after solder printing;
Determining the adhesion state of the solder of the squeegee based on the height at which the squeegee is raised when the predetermined upper pressure is applied;
A solder printing method comprising:

Images