JP4066752B2 - Screen printing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a screen printing apparatus that prints paste such as cream solder or conductive paste on a substrate.
[0002]
[Prior art]
In an electronic component mounting process, screen printing is used as a method for printing paste such as cream solder or conductive paste on a substrate. In this method, a mask plate in which pattern holes are formed according to a printing target portion is set on a substrate, and paste is printed on the substrate through the pattern holes of the mask plate by squeezing.
[0003]
As a screen printing squeezing method, a method using a sealed squeegee head is known. Unlike normal screen printing, this method uses a squeegee head provided with a paste storage container, instead of supplying the paste directly onto the mask plate. In this method, the paste is pushed into the pattern hole of the mask plate by pressurizing the paste in the paste storage container with the opening provided on the lower surface of the paste storage container being in contact with the mask plate. It is. Then, by sliding the squeegee head on the mask plate, the pattern holes are sequentially filled with paste (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-347635
[Problems to be solved by the invention]
However, screen printing using the above-described conventional sealed squeegee head has the following problems. As described above, in this method, the paste in the squeegee head is always pressed from above. For this reason, with the passage of time, the viscosity of the paste increases by pressurization from one direction and the fluidity decreases. The paste having poor fluidity has a problem that printing failure tends to occur as a result of the paste not being satisfactorily filled into the pattern holes even when the squeegee head is slid on the mask plate.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a screen printing apparatus that can prevent an increase in the viscosity of a paste inside a squeegee head and ensure printing quality.
[0007]
[Means for Solving the Problems]
The screen printing apparatus according to claim 1, wherein the screen printing apparatus prints a paste on a substrate through a pattern hole of the mask plate by moving the squeegee head on the mask plate, and the squeegee head is applied to the mask plate. And a horizontal movement means for moving up and down in the horizontal direction, a lifting means, and a pressing means for pressing the squeegee head against the mask plate, wherein the squeegee head is fixedly connected to the pressing means. A printing section held by the printing section, a paste storage section provided in the printing section for storing the paste therein, a paste pressurizing means for pressing the paste in the paste storage section, and a mask plate for storing the pressurized paste Form the printing space that touches the surface of the printer and the front and rear walls in the squeezing direction of this printing space. And two scraping members provided with a lower end abutting against the surface of the mask plate, and a rotating member in which a stirring groove portion inclined with respect to the axial direction is formed on the circumferential surface of the cylindrical stirring portion. An agitating member that is provided in the printing space and agitates the paste by rotating, a rotation driving means that rotationally drives the agitating member and that is provided at the connecting portion, and the rotation driving means and the agitating member are fitted and detached. A coupling means for freely coupling; and a control means for controlling the rotation driving means , and the rotation driving means is urged by a tension spring pivotally supported by a pin on the coupling portion and extended toward the coupling portion. A vertical plate, a motor disposed on an upper portion of the plate, a rotating shaft pivotally supported by a lower end portion of the plate and driven to rotate by the motor, and the coupling means includes: A coupling mechanism comprising a coupling on the driving side coupled to the rotating shaft and a coupling coupled to the end of the agitating member, and when the coupling mechanism is fitted, rotational torque is applied to the agitating member. The rotation transmission to the agitating member is released by tilting the plate against the tension of the tension spring with the pin as a fulcrum to disengage the coupling mechanism from the fitted state .
[0009]
According to the present invention, by performing the rotary stirring operation of stirring the paste by rotating the stirring member in the squeegee head, the viscosity of the paste can be prevented and the fluidity of the paste can be ensured.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. 1 is a front view of a screen printing apparatus according to an embodiment of the present invention, FIG. 2 is a side view of the screen printing apparatus according to an embodiment of the present invention, and FIG. 3 is a screen printing apparatus according to an embodiment of the present invention. 4 is a partial sectional view of the squeegee head, FIG. 4 is a perspective view of a stirring member provided in the squeegee head of the screen printing apparatus according to the embodiment of the present invention, and FIG. 5 is a screen printing apparatus according to the embodiment of the present invention. FIG. 6 is an explanatory view of a rotary stirring operation in the screen printing apparatus according to the embodiment of the present invention.
[0011]
First, the structure of the screen printing apparatus will be described with reference to FIGS. 1 and 2, the substrate positioning unit 1 is configured by disposing a substrate holding unit 2 on a moving table (not shown). The substrate 3 to be screen-printed is held by a clamper 4 of the substrate holding unit 2, and the substrate 3 held by the substrate holding unit 2 is positioned in the horizontal direction and the vertical direction by driving a moving table (not shown). .
[0012]
A screen mask 10 is disposed above the positioning unit 1. The screen mask 10 is configured by mounting a mask plate 12 on a holder 11, and a pattern hole 12 a corresponding to a printing portion of a substrate 3 to be printed is opened in the mask plate 12.
[0013]
A squeegee head 13 is disposed on the screen mask 10 so as to be movable up and down by a head lifting unit 20. The head elevating unit 20 includes a cylinder 22 erected on a base member 21, and a squeegee head 13 is coupled to a lower end portion of a rod 22 a of the cylinder 22 via a coupling member 15. By driving the cylinder 22, the squeegee head 13 moves up and down with respect to the mask plate 12, and the squeegee head 13 is pressed against the mask plate 12. The head elevating unit 20 is an elevating unit that elevates the squeegee head 13 with respect to the screen mask 10. The cylinder 22 is a pressing unit that presses the squeegee head 13 against the mask plate 12.
[0014]
Sliders 23 are fixed to both ends of the lower surface of the plate member 21 of the head elevating unit 20, and the sliders 23 are slidably fitted to guide rails 24 disposed on the upper surface of the frame 25. A nut member 26 is coupled to the lower surface of the plate member 21, and a feed screw 27 screwed into the nut 26 is rotationally driven by a motor 28.
[0015]
By driving the motor 28, the plate member 21 moves horizontally, and therefore the squeegee head 13 coupled to the head elevating unit 20 also moves horizontally. By driving the motor 28 with the squeegee head 13 lowered, the squeegee head 13 moves horizontally on the mask plate 12. That is, the motor 28, the feed screw 27, and the nut 26 serve as a horizontal moving unit that horizontally moves the squeegee head 13 on the mask plate 12.
[0016]
Below the squeegee head 13, there is provided a printing unit 14 that contacts the surface of the mask plate 12 and fills the pattern holes 12 a with cream solder 5 that is a paste. The printing unit 14 is held via a coupling member 15 that is fixedly connected to the rod 22 a of the cylinder 22. A horizontal holding bracket 17 that holds a stirring rotation driving unit 40 described below is coupled to the coupling member 15, and the cylinder 16 is held together with the stirring rotation driving unit 40 on the holding bracket 17. The coupling member 15 and the holding bracket 17 serve as a coupling portion that is fixedly coupled to the cylinder 22.
[0017]
As shown in FIG. 2, the printing unit 14 is horizontally provided with a stirring member 37 that rotates in a printing space, which will be described later, and stirs the cream solder. The stirring member 37 is interposed via a coupling mechanism 42. It is driven to rotate around the horizontal axis by the stirring rotation drive unit 40. The stirring rotation drive unit 40 includes a motor 41, and the motor 41 is driven by a motor drive unit 43. The motor drive unit 43 is controlled by the control unit 44, and at this time, the rotation direction and the rotation speed of the motor 41 are controlled according to the stirring pattern stored in the stirring pattern storage unit 45. The control unit 44 is a control unit that controls the rotation driving unit in accordance with a stirring pattern stored in advance.
[0018]
Next, the structure of the printing unit 14 will be described with reference to FIG. In FIG. 3, reference numeral 30 denotes a main body, which is a block-like member that is elongated in the width direction of the mask plate 12. As shown in FIG. 2, the length dimension of the main body 30 is set so as to cover the width dimension of the substrate 3 to be printed. The main body 30 is formed with a recess 30a in which the cartridge 31 storing the cream solder 5 is detachably mounted.
[0019]
The cartridge 31 is a cream solder storage part (paste storage part) in which a predetermined amount of cream solder is stored in advance, and is attached to the main body 30 during printing. A pressure plate 32 that pressurizes the internal cream solder 5 is fitted into the opening on the upper surface of the cartridge 31. The pressure plate 32 is coupled to the rod 16 a of the cylinder 16 held by the holding bracket 17, and the pressure plate 32 moves up and down within the cartridge 31 by driving the cylinder 16.
[0020]
The bottom surface of the cartridge 31 is a cream solder extrusion plate 31a, and the extrusion plate 31a has a large number of openings 31b. By pressing the pressure plate 32 downward by the cylinder 16, the cream solder 5 in the cartridge 31 is pressurized and pushed downward through the opening 31b of the extrusion plate 31a. The cylinder 16 and the pressure plate 32 serve as a paste pressurizing unit that pressurizes the paste 5.
[0021]
When the cream solder 5 is pushed out by the cylinder 16, it moves downward through the opening 31b of the push-out plate 31a. The extruded cream solder is formed in a space formed below the main body portion 30, that is, two scraping members 36 </ b> A and 36 </ b> B disposed obliquely inward at the lower portion of the main body portion 30 and the lower surface of the main body portion 30. The print space 35 surrounded by is reached. Both side surfaces of the printing space 35 are blocked by a blocking member 38 (see FIG. 2).
[0022]
The scraping members 36 </ b> A and 36 </ b> B form front and rear walls in the squeezing direction of the printing space 35, and the lower ends of the scraping members 36 </ b> A and 36 </ b> B come into contact with the surface of the mask plate 12 when the squeegee head 13 is lowered. During the printing operation, the printing space 35 accommodates the pressurized cream solder 5, and the cream solder 5 is brought into contact with the surface of the mask plate 12 through the opening between the scraping members 36A and 36B.
[0023]
Next, the stirring member 37 will be described with reference to FIG. As shown in FIG. 4, the stirring member 37 is a rotating member in which a stirring groove portion 37c is formed on the circumferential surface of a cylindrical stirring portion 37b. The stirring portion 37b is positioned in the printing space 35 and the end portion 37a is closed. It is arranged so as to protrude outward from a shaft support hole provided in the member 38. The stirring groove portion 37 c is a groove inclined with respect to the axial direction of the stirring member 37. A seal member 46 is attached to the shaft support hole to prevent the cream solder 5 from leaking out. A coupling 42b is coupled to the end portion 37a, and rotational torque is transmitted to the stirring member 37 by fitting the coupling 42b with the coupling 42a on the driving side.
[0024]
Next, with reference to FIG. 5, the structure of the stirring rotation drive part 40 is demonstrated. In FIG. 5A, a hinge plate 40b is provided on the right side surface of the vertical plate 40a. The hinge plate 40b is pivotally supported on the end of the holding bracket 17 by a pin 17a, and the plate 40a is allowed to rotate around the pin 17a. A tension spring 50 is stretched between the plate 40a and the holding bracket 17, and the plate 40a is urged in the arrow direction.
[0025]
A motor 41 is disposed in a horizontal posture on the upper portion of the plate 40 a, and a pulley 47 is coupled to the rotating shaft of the motor 41. A rotating shaft 48a coupled to a coupling member 42a constituting the coupling mechanism 42 is pivotally supported at the lower end portion of the plate 40a, and a pulley 48 is coupled to the rotating shaft 48a. A belt 49 is tuned between the pulleys 47 and 48, and rotation is transmitted to the rotating shaft 48 a via the belt 49 by driving the motor 41 to rotate. The stirring rotation driving unit 40 is a rotation driving unit that rotates the stirring member 37. An actuator other than a motor, such as a cylinder, may be used as a drive source for the rotation drive means.
[0026]
As shown in FIG. 5 (b), when the plate 40a is tilted against the tension of the tension spring 50 with the pin 17a as a fulcrum, the coupling member 42a is detached from the fitted state with the coupling member 42b and stirred. The rotation transmission to the member 37 is released. Therefore, the coupling mechanism 42 is a coupling means that couples the stirring rotation driving unit 40 and the stirring member 37 in a freely detachable manner. Thereby, when attaching and detaching the printing unit 14, the stirring rotation driving unit 40 and the stirring member 37 can be connected with only a simple operation.
[0027]
As shown in FIG. 6A, the cream solder 5 moves through the push-out plate 31 a and into the printing space 35 by pressing down the pressure plate 32 to pressurize the cream solder 5 in the cartridge 31. In the middle of the movement path of the cream solder 5 is a throttle portion whose cross-sectional area is narrowed by a large number of small openings 31b, and the pressurized cream solder 5 passes through the throttle portion (arrow a). The fluidity of the cream solder 5 is improved. Further, as the stirring member 37 rotates, the cream solder 5 is given a stirring motion in the rotational direction as indicated by arrows b and c.
[0028]
At this time, since the stirring groove 37c (see FIG. 4) is provided on the surface of the stirring portion 37b as shown in FIG. 5B, the cream solder 5 near the surface of the stirring member 37 in the printing space 35 is provided. Is provided with a stirring motion including not only a circumferential rotational component but also an axial moving component. By this rotational stirring operation, the viscosity of the cream solder 5 is lowered and modified to a property suitable for screen printing.
[0029]
Here, an operation pattern of the rotating stirring operation performed by rotating the stirring member 37 will be described. In the screen printing, the squeegee head 13 in a state where the cream solder 5 modified to have an appropriate viscosity as described above is filled in the printing space 35 is slid on the mask plate 12. By this horizontal movement, the cream solder 5 in contact with the mask plate 12 is given a motion component due to rolling as indicated by arrows d and e. The flow direction and flow state of the cream solder 5 due to this rolling vary depending on the printing direction and the printing speed. That is, the flow direction is reversed depending on the moving direction of the squeegee head 13, and the degree of flow varies depending on the printing speed.
[0030]
For this reason, in the screen printing method shown in the present embodiment, the rotation pattern (rotation direction, rotation speed, rotation intermittent interval, etc.) of the stirring member 37 is used in order to perform an optimal stirring operation for the purpose of a desired modification effect. ) Is set in advance according to printing conditions such as printing speed and printing pressure, and is stored in the stirring pattern storage unit 45. Thereby, the stirring member 37 is rotated according to the optimal stirring operation pattern according to the state of the cream solder 5 in the printing space 35, and the cream solder 5 is always kept at an appropriate viscosity.
[0031]
The cream solder 5 in the printing space 35 maintained at an appropriate viscosity in this way is filled into the pattern hole 12a of the mask plate 12 through the opening between the scraping members 36A and 36B. Then, by moving the squeegee head 13, the cream solder 5 is sequentially filled into each pattern hole 12a. If cream solder is filled in all the pattern holes 12a, the substrate holding part 2 is lowered to release the plate.
[0032]
That is, the cream solder 5 in the pattern hole 12a descends together with the substrate 3 and is separated from the pattern hole 12a, thereby completing the cream solder printing on the substrate 3. In this screen printing, the cream solder 5 is maintained at an appropriate viscosity by a rotating stirring operation, and fluidity is ensured. Therefore, satisfactory filling into the pattern holes 12a is ensured, and the print quality can be maintained.
[0033]
In the above-described embodiment, an example in which only one stirring member 37 is disposed has been described. Of course, a plurality of stirring members 37 may be disposed. Moreover, although the cylindrical shape which provided the stirring groove on the surface is used as the cross-sectional shape of the stirring member 37, the thing of various shapes, such as what provided the fin-shaped protrusion on the surface other than this, is used. be able to.
[0034]
【The invention's effect】
According to the present invention, since the rotating stirring operation of rotating the stirring member in the squeegee head to stir the paste is performed, increase in the viscosity of the paste can be prevented and the fluidity of the paste can be ensured.
[Brief description of the drawings]
FIG. 1 is a front view of a screen printing apparatus according to an embodiment of the present invention. FIG. 2 is a side view of a screen printing apparatus according to an embodiment of the present invention. FIG. 4 is a perspective view of a stirring member provided in a squeegee head of a screen printing apparatus according to an embodiment of the present invention. FIG. 5 is a screen printing apparatus according to an embodiment of the present invention. FIG. 6 is an explanatory diagram of the mechanism of rotation driving means provided in the squeegee head of FIG. 6;
3 Substrate 5 Cream solder 12 Mask plate 12a Pattern hole 13 Squeegee head 14 Printing unit 16 Cylinder 31 Cartridge 32 Pressure plate 35 Printing space 37 Stirring member 40 Stirring rotation driving unit 41 Motor 44 Control unit 45 Stirring pattern storage unit

Claims (1)

A screen printing apparatus for printing a paste on a substrate through a pattern hole of a mask plate by moving the squeegee head on the mask plate, and moving the squeegee head in a horizontal direction with respect to the mask plate to move up and down Horizontal movement means for moving up and down, and pressing means for pressing the squeegee head against the mask plate, wherein the squeegee head is held by a connecting portion fixedly connected to the pressing means, and this printing A paste storage section provided in the section for storing the paste therein, a paste pressurizing means for pressing the paste in the paste storage section, a printing space for storing the pressed paste and contacting the surface of the mask plate, and Forms front and rear walls in the squeezing direction of the printing space, and the lower end is the surface of the mask plate Two scraping members provided in contact with, that a rotary member formed with stirring grooves inclined relative to the axial direction to rotate provided on the printed space in the circumferential surface of the cylindrical stirring portion An agitating member for agitating the paste, a rotation driving means provided on the connecting portion by rotationally driving the agitating member, a coupling means for detachably coupling the rotation driving means and the agitating member, and the rotation Control means for controlling the drive means ,
Further, the rotation driving means includes a vertical plate that is pivotally supported by a pin on the connecting portion and is extended toward the connecting portion, a vertical plate that is urged by a tension spring, a motor disposed on an upper portion of the plate, and the plate A rotary shaft that is pivotally supported by the lower end of the motor and driven to rotate by the motor,
Further, the coupling means includes a coupling mechanism comprising a driving side coupling coupled to the rotating shaft and a coupling coupled to an end of the stirring member,
When the coupling mechanism is fitted, rotational torque is transmitted to the agitating member, and the plate is tilted against the tension of the tension spring with the pin as a fulcrum, and the coupling mechanism is removed from the fitted state. Accordingly, the rotation transmission to the agitating member is released, so that the screen printing apparatus is characterized.

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