JP2006168028A - Screen printing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide screen printing equipment which ensures printing quality and can prevent a leak of paste due to the weight of its own, by a simple constitution. <P>SOLUTION: While a squeegee head 13 holding the solder paste 5 is moved, the solder paste 5 is pressed by a pressing plate 32 and printed on a substrate 3 through pattern holes 12a of a mask plate 12. In this screen printing equipment, a plate-shaped leak preventing member 40 is disposed just above an opening 37 formed in the lower side of the squeegee head 13, so as to cover the opening 37 from inside. The member has through-holes 40a of such dimensions as to be enough to prevent the leak of the paste 50 in the head main body part from the opening 37 on the occasion of non-contact of the squeegee head 13 with the surface of the mask plate 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printing apparatus for printing paste that prints a paste agent such as cream solder or conductive paste on a circuit board on which electronic components are mounted or a substrate of a solar cell, for example.

  In recent years, screen printing apparatuses have been used, for example, in a printing process of cream solder or conductive paste in a circuit mounting process of electronic components. The screen printing apparatus is an apparatus that sets a mask plate having a pattern hole formed in accordance with a printing target portion on a substrate, and prints a paste on the substrate through the pattern hole of the mask plate by squeezing.

As this screen printing apparatus, an apparatus having a sealed squeegee head is known. This apparatus uses a sealed squeegee head in which the paste is stored inside, instead of directly supplying the paste onto the mask plate. In this apparatus, with the opening provided on the lower surface of the head main body being in contact with the mask plate, the paste discharged through the opening is applied to the pattern holes of the mask plate by pressurizing the paste in the head main body. Pushed in. Then, by sliding the squeegee head on the mask plate, each pattern hole is sequentially filled with paste (see, for example, Patent Document 1).
JP 2001-246729 A

  However, various pastes such as cream solder stored in the squeegee head in the screen printing apparatus are used depending on the purpose and conditions of use. For example, examples of the paste include a solder paste such as cream solder, silver paste, and aluminum paste. Each of these pastes has a unique physical property value and a different viscosity. For example, cream solder or the like is about 200 Pa · S, but silver paste or the like is about 100 Pa · S.

  Since the squeegee head can cope with pastes having different physical properties as described above, the squeegee head is configured to perform appropriate printing using any paste. However, as described above, when a low-viscosity paste is used, the paste stored inside falls from the opening of the squeegee head due to its own weight and leaks, and the paste tends to be insufficient, and appropriate printing is performed. There was a problem that I could not. For this reason, if the squeegee head designed for each paste is replaced, the leakage of the above paste can be solved, but not only is the trouble of replacing the squeegee head when using the device. The configuration of the apparatus becomes complicated and there is a problem of cost.

  Therefore, the technical problem to be solved by the present invention is to provide a screen printing apparatus capable of ensuring printing quality and preventing leakage due to dropping of the paste by its own weight with a simple configuration.

  In order to solve the above technical problems, the present invention provides a screen printing apparatus having the following configuration.

According to the first aspect of the present invention, a squeegee head and a moving device for moving the squeegee head in a substantially horizontal direction with respect to the mask plate are provided, and the squeegee head is moved on the mask plate by the moving device. A screen printing apparatus for printing a paste on a substrate through a pattern hole of a mask plate,
The squeegee head is
A cylindrical member having an opening for pressurization and a bottom wall of the cylindrical member are formed, and a discharge opening for discharging the paste is defined therebetween, and each lower end portion is in sliding contact with the upper surface of the mask plate A head main body portion having two blade portions arranged opposite to each other, and storing a paste therein,
A paste pressurizing unit that pressurizes the paste in the cylindrical member through the pressurizing opening and discharges the paste from the discharge opening;
The paste in the head main body is disposed immediately above the lower end of the contact portion so as to cover the discharge opening from the inside of the head main body, and when the squeegee head and the surface of the mask plate are not in contact with each other. And a plate-shaped leakage prevention member having a through hole to prevent leakage from the discharge opening.

  In the above configuration, the screen printing apparatus sets the mask plate with the pattern holes opened according to the print target portion on the substrate, and moves the squeegee head to form the substrate through the pattern holes of the mask plate. This is a device for printing paste. Therefore, the squeegee head is configured to be in contact with the surface of the mask plate and pressed against the surface of the mask plate during printing.

  The squeegee head is a so-called hermetically sealed squeegee head, and includes a cylindrical member having an opening for inserting a pressurizing member above and a blade portion defining the opening by forming a bottom wall of the cylindrical member. With. The paste in the squeegee head is pressurized by the paste pressing unit during printing and discharged from the discharge opening. The discharge opening is provided with a leakage preventing member having a through hole immediately above the discharge opening to prevent paste from leaking from the opening.

  The leakage preventing member increases the contact area with the paste through the through-hole, supports the paste from below, and applies a surface tension to the paste to prevent the leakage of the paste from the discharge opening.

  According to the first aspect of the present invention, the paste stored inside the squeegee head is self-weighted by the leakage preventing member disposed so as to cover the opening immediately above the discharge opening defined by being sandwiched between the blade portions. It is possible to prevent leakage. In addition, since the leakage preventing member is directly above the lower end portion of the squeegee head, the amount of the paste located below the leakage preventing member is reduced, and the lower paste is prevented from falling due to its own weight. In addition, during printing, when the lower end portion of the blade portion is in sliding contact with the mask plate, there is no interference and the printing operation is not hindered.

  Next, before describing the screen printing apparatus according to the embodiment of the present invention in detail, various aspects of the present invention will be described.

According to the first aspect of the present invention, the apparatus includes a squeegee head and a moving device that moves the squeegee head in a substantially horizontal direction with respect to the mask plate, and the moving device moves the squeegee head on the mask plate, A screen printing apparatus for printing a paste on a substrate through a pattern hole of a mask plate,
The squeegee head is
A cylindrical member having an opening for pressurization and a bottom wall of the cylindrical member are formed, and a discharge opening for discharging the paste is defined therebetween, and each lower end is in sliding contact with the upper surface of the mask plate A head main body portion having two blade portions arranged opposite to each other, and storing a paste therein,
A paste pressurizing unit that pressurizes the paste in the cylindrical member through the pressurizing opening and discharges the paste from the discharge opening;
The paste in the head main body is disposed immediately above the lower end of the contact portion so as to cover the discharge opening from the inside of the head main body, and when the squeegee head and the surface of the mask plate are not in contact with each other. And a plate-shaped leakage prevention member having a through hole to prevent leakage from the discharge opening.

  According to a second aspect of the present invention, the leakage preventing member includes a through hole having a size that allows the paste to exert a surface tension to the extent that the paste does not fall from the through hole due to its own weight. A screen printing apparatus according to a first aspect is provided.

  According to a third aspect of the present invention, the leakage preventing member has a plurality of through holes having the dimensions of 0.5 to 3.0 mm, and has an opening ratio of 30 to 90%. A screen printing apparatus according to the first or second aspect is provided.

  According to the fourth aspect of the present invention, the leakage preventing member is composed of a plate member having a width that is slightly larger than the opening, and is detachably mounted on the inner surface of the blade portion. A screen printing apparatus according to any one of the first to third aspects, wherein the screen printing apparatus is attached to a main body.

  According to the fifth aspect of the present invention, the head main body portion includes a fixing portion arranged opposite to the squeezing direction and fixing the blade portion to the lower side thereof at the lower end of the main body portion, A screen printing apparatus according to any one of the first to fourth aspects is provided, comprising a positioning portion that fits the leakage preventing member and positions the leakage preventing member in the squeezing direction.

  According to a sixth aspect of the present invention, the leakage preventing member is configured such that a dimension in a direction orthogonal to the squeezing direction is substantially equal to an inner dimension in a direction orthogonal to the squeezing direction of the tubular member, A screen printing apparatus according to any one of the first to fifth aspects, wherein the screen printing apparatus is fixed in a direction crossing the squeezing direction by an inner surface of a cylindrical member.

  According to a seventh aspect of the present invention, there is provided the screen printing apparatus according to any one of the first to sixth aspects, wherein the leakage preventing member has the through holes arranged uniformly over the entire surface. To do.

  According to an eighth aspect of the present invention, there is provided the screen printing apparatus according to any one of the first to seventh aspects, wherein the leakage prevention member is a plate whose entire surface is formed of a lattice mesh. provide.

  According to the ninth aspect of the present invention, the leakage preventing member is attached to the head main body when a paste having a viscosity of 10 to 200 Pa · S is used, and when the paste having a viscosity of 200 Pa · S or more is used. The screen printing apparatus according to any one of the first to eighth aspects is provided, wherein the screen printing apparatus is removed from the head main body.

  Hereinafter, a screen printing apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  First, the structure of the screen printing apparatus 100 will be described with reference to FIGS. In FIG. 1, a substrate positioning unit 1 is configured by stacking an X-axis table 2, a Y-axis table 3, a θ-axis table 4, and a Z-axis table 5. A lower receiving portion 6 that supports the substrate 7 is provided. The substrate 7 is clamped on both sides by the clamp portion 8 and held. By driving each axis table of the positioning unit 1, the substrate 7 held by the lower receiving unit 6 is positioned in the horizontal direction and the vertical direction.

  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 head main body portion of a substrate 7 to be printed is opened in the mask plate 12. On the screen mask 10, a squeegee head 13 is disposed so as to be movable up and down by a head lifting unit 20. The squeegee head 13 is a hermetically sealed squeegee head capable of storing cream solder as a paste. The squeegee head 13 moves the squeegee head 13 on the mask plate 12 to allow the substrate 7 to pass through the pattern holes 12 a of the mask plate 12. Print cream solder.

  The head elevating unit 20 includes a cylinder 22 provided on the base member 21. 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.

  Sliders 23 are fixed to both ends of the lower surface of the base 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 base member 21, and a feed screw 27 screwed into the nut 26 is rotationally driven by a motor 28.

  By driving the motor 28, the base member 21 moves horizontally, and thus the squeegee head 13 coupled to the head lifting / lowering 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.

  Next, the squeegee head will be described. Below the squeegee head 13 is provided a head main body 14 that contacts the surface of the mask plate 12 and fills the pattern holes 12a with cream solder as paste. The structure of the head main body 14 will be described with reference to FIG. In FIG. 3, the head body 14 is a block-shaped cylindrical member that is elongated in the width direction of the mask plate 12. The upper side has a pressurizing opening 34 for pressurizing the paste, and the lower side has an opening 37 for discharging the paste. A printing space 35 is provided and accommodates cream solder used for printing. The longitudinal dimension of the head main body 14 is set so as to cover the width dimension of the substrate 7 to be printed as shown in FIG. The head main body portion 14 is fixed to the lower side of the paste storage portion 30 in which the concave portion 30 a in which the cartridge 31 in which the cream solder 50 is stored is detachably mounted is formed, and the pressurizing opening 34 is formed by the paste storage portion 30. Sealed.

  A cartridge 31 in which a predetermined amount of cream solder 50 is stored in advance is set in the paste storage unit 30. As described above, the paste reservoir 30 is connected to the head main body 14 during printing. On the upper surface of the paste reservoir 30, an opening for inserting a pressure plate 32 that pressurizes the internal cream solder 50 is provided. The pressure plate 32 is coupled to the rod 16 a of the cylinder 16 disposed above, and the pressure plate 32 moves up and down in the paste storage unit 30 by driving the cylinder 16.

  The bottom surface of the paste reservoir 30 is an extrusion plate 33 for the cream solder 50, and the extrusion plate 33 is provided with a number of through holes 33a. By pressing the pressure plate 32 downward by the cylinder 16, the cream solder 50 in the cartridge 31 is pressurized and pushed downward through the through hole 33 a of the push plate 33.

  Each of the blade portions 36A and 36B is a plate-like member having a dimension substantially equal to the longitudinal direction dimension of the head main body portion 14, and forms a part of the bottom plate of the head main body portion 14, and is the center in the squeezing direction of the printing space. The portions are inclined so as to be deeper and are arranged opposite to each other in the squeezing direction. An opening 37 is defined in the gap between the two blade portions 36A and 36B. When the squeegee head 13 is lowered, the lower end portions 38A and 38B (see FIG. 7) of the blade portions 36A and 36B abut against the surface of the mask plate 12. During the printing operation, the printing space 35 accommodates the pressurized cream solder 50 and brings the cream solder 50 into contact with the surface of the mask plate 12 through the opening 37 between the blade portions 36A and 36B.

  Immediately above the opening 37, a leakage preventing member 40 provided with a large number of through holes 40a is mounted. The leak preventing member 40 is a plate-like member configured such that the width dimension in the squeezing direction is slightly larger than the opening 37, and is supported by the inner surfaces of the blade portions 36A and 36B from the inside of the printing space 35. It arrange | positions so that the opening 37 may be covered. The leak preventing member 40 will be described in detail later.

  When the cream solder 50 in the cartridge 31 is pushed out by the cylinder 16, it passes through the through hole 33 a of the push-out plate 33. The extruded cream solder 50 passes through the pressurizing opening 34 of the head main body part, and is located in a space located below the pressurizing opening 34, that is, two blades disposed obliquely inward in the lower part of the main body part 30. The print space 35 surrounded by the portions 36A and 36B and the lower surface of the main body 30 is reached.

  By pressing down the pressurizing plate 32 to pressurize the cream solder 50 in the cartridge 31, the cream solder 50 moves through the pusher plate 33 and into the printing space 35. In the middle of the movement path of the cream solder 50, there is a narrowed portion whose cross-sectional area is narrowed by a large number of small through holes 33a. The viscosity of 50 is reduced, and the properties suitable for screen printing are modified.

  In the screen printing, the internal cream solder 50 is pressurized by the pressure plate 32, and the squeegee head 13 in a state where the cream solder 50 modified to the proper viscosity as described above is filled in the printing space 35 is used as a mask. Slide on plate 12. As a result, the cream solder 50 in the printing space 35 is filled into the pattern holes 12a of the mask plate 12 through the discharge openings 37 between the blade portions 36A and 36B.

  Then, by moving the squeegee head 13, cream solder 50 is sequentially filled in each pattern hole 12 a. If cream solder is filled in all the pattern holes 12a, the substrate holding part 2 is lowered to release the plate. That is, the cream solder 50 in the pattern hole 12a descends together with the substrate 7 and is separated from the pattern hole 12a, whereby the screen printing of the cream solder 50 on the substrate 7 is completed.

  Next, the leakage preventing member 40 will be described. The leakage preventing member is a member for preventing cream solder or the like, which is a paste stored in the printing space 35 through the through hole 33 a of the extrusion plate 33, from leaking from the discharge opening 37. That is, paste having various properties is used as the paste used in the screen printing apparatus depending on the purpose of use. Also, the viscosity of the paste used varies depending on the type. For example, cream solder or the like is about 200 Pa · S, but silver paste or the like is about 100 Pa · S. . Since the squeegee head 13 can handle pastes having different physical properties as described above, it is necessary to configure the squeegee head 13 so that appropriate printing can be performed using any paste. However, as described above, when a low-viscosity paste is used, the paste stored in the printing space 35 falls from the discharge opening 37 of the squeegee head 13 and leaks due to its own weight. . The leakage preventing member 40 is a member for preventing this leakage. That is, the leakage preventing member 40 may be used when a low-viscosity paste of about 10 to 200 Pa · S, preferably about 50 to 200 Pa · S is used. When used, it is not always necessary to use it.

  As an example, as shown in FIG. 4A, FIG. 4B, etc., the leakage preventing member 40 has a structure in which a through hole 40a is formed in a plate-like member made of metal or a resin excellent in solvent resistance. The leakage preventing member 40 is disposed in the printing space of the head main body 14 so as to cover the ejection opening 37, and is supported and fixed on the inner surfaces of the blade portions 36A and 36B. Further, it is preferable that the leak preventing member 40 is disposed immediately above the discharge opening 37. That is, if the squeegee head 13 protrudes downward from the discharge opening 37, the squeegee head 13 comes into contact with the mask plate when pressed against the mask plate, and printing cannot be performed properly. This is because the amount of paste that passes through the leakage prevention member 40 and exists below the leakage prevention member 40 increases, and the leakage of the paste easily occurs from the discharge opening 37 due to the weight of the paste. Therefore, the width direction dimension D of the leakage preventing member 40 in the squeegeeing direction is preferably configured to be slightly larger than the width of the discharge opening 37 of the squeegee head 13, and is supported in the vicinity of the lower end side of the blade portions 36A and 36B. It is preferable to do so.

  As shown in FIG. 4A, the leakage prevention member 40 is constituted by a plate-like member 40b having a through hole 40a, and as shown in FIG. 4B, the leakage prevention member 40 is a plate-like member entirely constituted by a mesh. Also good. The through hole 40a may be a round hole or a square hole. Moreover, the through hole 40a may be configured in a slit shape as shown in FIG. 4C. The through holes 40a are desirably provided uniformly on the entire surface of the leakage preventing member 40 in order to allow the paste to pass therethrough uniformly.

  Moreover, although the dimension of the through-hole 40a can be designed by the paste to be used, it is preferable that the outer dimension is generally about 0.5 to 3.0 mm, and the dimension may be set larger as the viscosity of the paste is higher. Moreover, it is preferable that the opening ratio of a leakage preventing member is 30 to 90%, and it is preferable to use a thing with a larger opening ratio as the viscosity of the paste is higher. Here, the aperture ratio is indicated by the ratio of the area of the through hole 40a to an arbitrary region where the through hole of the leakage preventing member is formed. That is, for example, in the case of a leakage preventing member in which no through hole is formed in the end portion, the aperture ratio is determined based on an arbitrary region excluding the end portion.

  As shown in FIG. 5A, the through holes 40a may be provided with the same dimension over the thickness direction of the plate 40b of the leakage preventing member 40, or may be configured to have different dimensions as shown in FIG. 5B. Also good. The through hole 40a may be a round hole or a square hole. The thickness dimension of the plate 40b of the leakage preventing member 40 is preferably about 0.1 to 1.0 mm. In the example of the through hole 40a shown in FIG. 5B, the dimension is configured to decrease as it approaches the mask plate 12 side, but is not particularly limited to this configuration, for example, the thickness direction center of the leakage prevention member 40 You may be comprised so that a part may become small.

  Further, the longitudinal dimension L of the leakage preventing member 40 is configured to be substantially the same as the longitudinal inner dimension of the head main body 14. Therefore, when the leakage preventing member is disposed in the head main body 14, there is no deviation in the longitudinal direction.

  Next, the arrangement of the leakage preventing member 40 on the head main body 14 will be described. As shown in FIG. 6, the leakage preventing member 40 is disposed from the upper side of the head main body 14 inside. As described above, since the longitudinal dimension of the leakage preventing member is substantially the same as the longitudinal inner dimension of the head main body 14, it prevents the longitudinal displacement when it is within the head main body 14. be able to. Further, since the transverse dimension D of the leakage preventing member 40 is configured to be slightly larger than the width dimension E of the discharge opening 37, the edge 41 contacts the inner surface of the blade parts 36A and 36B, It does not fall out from the discharge opening 37.

  Further, as shown in FIG. 7, a positioning portion 17 may be provided in the head main body portion 14 in order to fix the position of the leakage preventing member 40 in the short direction. In the example of FIG. 7, the positioning portion 17 is provided at the end of the fixing portion 18 for fixing the blade portions 36A and 36B. Specifically, the fixing portion 18 for fixing the blade portions 36A and 36B is provided opposite to the side in the short direction of the head main body so as to constitute a part of the bottom wall of the head main body. The blade portions 36A and 36B are fixed to the lower side. That is, a step is formed in the vicinity of the end of the fixed portion 18 at the boundary between the blade portions 36A, 36B and the fixed portion 18, and the leakage preventing member 40 is fitted to the positioning portion 17 that is the step. With this configuration, the leakage preventing member 40 can be detachably disposed in the head main body 14 and can be prevented from shifting in the short direction (that is, the squeezing direction).

  As described above, the leakage preventing member 40 disposed immediately above the opening of the head main body 14 prevents the paste existing in the printing space 35 from dropping from the opening due to its own weight. That is, the leakage preventing member 40 has a through hole 40a having a size smaller than that of the discharge opening 37, supports the paste from the lower side in a portion where the hole is not opened, and is stronger to the paste existing in the through hole 40a. Demonstrate surface tension. The surface tension acting on the paste is a force for shrinking the paste, and it does not overcome the gravity due to the weight of the paste and does not drop the paste through the through hole 40a. That is, it is possible to prevent the paste in the printing space 35 of the head main body portion 14 from leaking from the ejection opening 37 due to its own weight.

  Therefore, it is desirable that the leakage preventing member 40 includes a through hole having a size that can cause the paste to have a surface tension that does not drop from the through hole 40a due to its own weight, as described above. What is necessary is just to change suitably according to the physical property. Specifically, the dimensions and opening ratios of the through holes of the leakage preventing member 40 are made different according to physical properties such as the viscosity and density of the paste. That is, since the leakage preventing member 40 is detachably attached to the head main body 14, the leakage preventing member 40 appropriately designed according to the type of paste can be disposed on the head main body 14. Further, when the paste has a high viscosity and no leakage from the discharge opening 37 occurs, the screen printing apparatus can be used without disposing the leakage preventing member 40 in the head main body portion 14.

  As described above, according to the screen printing apparatus according to the present embodiment, since the discharge opening 37 is covered by the leakage preventing member 40 provided immediately above the discharge opening 37, the print space 35 has the inside. The existing paste can be prevented from leaking from the discharge opening 37, and there is no hindrance when the lower ends of the blade portions 36A and 36B are in sliding contact with the mask plate.

  Further, since the leakage preventing member 40 is detachably disposed on the head main body 14, an appropriate member can be appropriately used according to the type of paste used. That is, since it is not necessary to replace the squeegee head itself according to the type of paste, the cost of the screen printing apparatus can be reduced, and the labor involved in replacing the squeegee head itself can be saved.

  In addition, this invention is not limited to the said embodiment, It can implement in another various aspect. For example, the configuration for positioning when the leakage preventing member 40 is arranged in the head main body 14 is appropriately provided with, for example, a protrusion or a recess for fixing the leakage preventing member in addition to the configuration shown in FIG. Can be changed.

  Further, the configuration of the through hole of the leakage preventing member 40 is not limited to the configuration employing the plurality of independent holes illustrated in FIGS. 4A to 4C, and one continuous hole may be provided.

1 is a front view of a screen printing apparatus according to an embodiment of the present invention. It is a partial side view of the screen printing apparatus of FIG. It is a fragmentary sectional view of the squeegee head of the screen printing apparatus of FIG. It is a top view which shows an example of the leak prevention member used for the squeegee head of the screen printing apparatus of FIG. It is a top view which shows the other example of the leakage prevention member used for the squeegee head of the screen printing apparatus of FIG. It is a top view which shows the further another example of the leak prevention member used for the squeegee head of the screen printing apparatus of FIG. It is a partial expanded sectional view which shows an example of the leakage prevention member used for the squeegee head of the screen printing apparatus of FIG. It is a partial expanded sectional view which shows the other example of the leak prevention member used for the squeegee head of the screen printing apparatus of FIG. It is a figure which shows the state by which the leakage prevention member is arrange | positioned in a printing container. It is a partial expanded sectional view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positioning part 2 X-axis table 3 Y-axis table 4 θ-axis table 5 Z-axis table 6 Bottom receiving part 7 Substrate 8 Clamp part 10 Screen mask 11 Holder 12 Mask plate 12a Pattern hole 13 Squeegee head 14 Head body part 16 Cylinder 20 Head Lifting part 21 Base member 22 Cylinder 23 Slider 24 Guide rail 25 Frame 26 Nut member 27 Feed screw 28 Motor 30 Paste storage part 31 Cartridge 32 Pressure plate 33 Extrusion board 35 Print space 36A, 36B Blade part 37 Discharge opening 38A, 38B Lower end Part 40 Leakage prevention member 100 Screen printing apparatus

Claims (9)

A squeegee head, and a moving device for moving the squeegee head in a substantially horizontal direction with respect to the mask plate, and the printed material through the pattern hole of the mask plate by moving the squeegee head on the mask plate by the moving device. A screen printing device for printing a paste on
The squeegee head is
A cylindrical member having an opening for pressurization and a bottom wall of the cylindrical member are formed, and a discharge opening for discharging the paste is defined therebetween, and each lower end portion is in sliding contact with the upper surface of the mask plate A head main body portion having two blade portions arranged opposite to each other, and storing a paste therein,
A paste pressurizing unit that pressurizes the paste in the cylindrical member through the pressurizing opening and discharges the paste from the discharge opening;
The paste in the head main body is disposed immediately above the lower end of the contact portion so as to cover the discharge opening from the inside of the head main body, and when the squeegee head and the surface of the mask plate are not in contact with each other. And a plate-like leakage prevention member having a through hole to prevent leakage from the discharge opening.   2. The screen printing apparatus according to claim 1, wherein the leakage preventing member includes a through hole having a size capable of applying a surface tension to the paste so that the paste does not fall from the through hole due to its own weight. .   3. The screen printing apparatus according to claim 1, wherein the leakage prevention member has a plurality of through holes having a size of 0.5 to 3.0 mm, and an opening ratio of 30 to 90%. .   The leakage preventing member is composed of a plate member having a width that is slightly larger than the discharge opening, and is mounted on the head main body portion detachably by being placed on the inner surface of the blade portion. The screen printing apparatus according to any one of claims 1 to 3.   The head main body portion is disposed opposite to the squeezing direction and includes a fixing portion that fixes the blade portion to the lower side thereof at the lower end of the main body portion, and the fixing portion is fitted with the leakage preventing member, 5. The screen printing apparatus according to claim 1, further comprising a positioning unit that positions the leakage prevention member in the squeezing direction.   The leakage preventing member has a dimension in a direction perpendicular to the squeezing direction and is substantially equal to an inner dimension in a direction perpendicular to the squeezing direction of the cylindrical member, and the squeezing is performed by an inner surface of the cylindrical member. The screen printing apparatus according to claim 1, wherein the screen printing apparatus is fixed in a direction crossing the direction.   The screen printing apparatus according to any one of claims 1 to 6, wherein the leakage preventing member has the through holes arranged uniformly over the entire surface.   The screen printing apparatus according to claim 1, wherein the leakage prevention member is a plate whose entire surface is formed of a lattice mesh.   The leakage preventing member is attached to the head main body when using a paste having a viscosity of 10 to 200 Pa · S, and is removed from the head main body when using a paste of 200 Pa · S or more. The screen printing apparatus according to any one of claims 1 to 8.

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