JP2012030507A - Squeegee and screen printing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a squeegee and screen printing apparatus capable of adjusting viscosity of paste supplied on a screen plate.SOLUTION: The squeegee 11 for scraping non-Newtonian fluid paste includes: a bent part 40 bent inwardly in a moving direction in plan view; and a linear part 41 extending outwardly in a linear state from both ends of the bent part in plan view. The squeegee 11 has an angle θ formed of the linear part 41 and the bent part 40 which is changeable when the upper part is held by a holder 45.

Description

The present invention relates to a squeegee and a screen printing apparatus for printing an electrode on a substrate, for example.

In the solar cell, a plurality of electrode portions running in the same direction are formed on the surface. This electrode part is formed by screen printing. In screen printing, if the viscosity of the paste remains high, it becomes difficult to fill the paste in the openings for forming the electrode pattern of the screen plate. As a result, printing unevenness or the like occurs and print quality deteriorates. Here, since the paste is a non-Newtonian fluid, the viscosity (apparent viscosity) is lowered by applying a shearing force from the outside to flow. Therefore, conventionally, an operator kneads a paste based on experience, adjusts the viscosity to be suitable for screen printing, and applies an appropriate amount onto the screen plate. However, the viscosity varied and the print quality was not stable.

In order to solve this problem, the coating apparatus described in Patent Document 1 includes a paste tank that stores a paste that is a non-Newtonian fluid, a tube or pipe that supplies the paste from the paste tank to the film formation region, and a stirring blade. A viscosity adjusting mechanism. In this coating apparatus, the viscosity of the paste is appropriately adjusted by bringing the paste supplied from the paste tank close to the viscosity of the paste formed on the screen plate by the viscosity adjusting mechanism.

JP 2010-5564 A

However, with this coating apparatus, it has not been possible to adjust the viscosity of the paste supplied on the screen plate.
An object of this invention is to provide the squeegee and screen printing apparatus which can adjust the viscosity of the paste supplied on the screen plate.

The screen printing apparatus according to the first invention that meets the above-mentioned object is a screen printing apparatus provided with a squeegee that scrapes off a paste of non-Newtonian fluid,
The squeegee is attached so that an attack angle is substantially 90 degrees, and a curved portion that curves inward in a scraping direction for scraping the paste in plan view, and a curved portion of the curved portion in plan view. A straight portion extending outwardly in a straight line from both ends,
A lower corner portion of the squeegee on the scraping direction side is chamfered.

The screen printing apparatus according to the first aspect of the present invention can further include a first variable mechanism that varies an angle formed by the curved portion and the linear portion.

In the screen printing apparatus according to the first aspect of the invention, a second variable mechanism that makes the bending degree of the bending portion variable can be provided instead of the first variable mechanism.

The squeegee according to the second invention that meets the above object is a squeegee that scrapes off a paste of non-Newtonian fluid,
A curved portion that curves inward in the scraping direction to scrape off the paste in plan view;
A straight portion extending outwardly in a straight line from both ends of the curved portion in plan view,
The lower corner of the scraping direction side is chamfered.

In the screen printing apparatus according to claims 1 to 3, since the squeegee has a curved portion and a straight portion, the rolling of the paste is promoted, and the viscosity of the paste supplied onto the screen plate can be adjusted. It is.

In the screen printing apparatus according to claim 2, since the first variable mechanism that changes the angle formed by the curved portion and the straight portion is provided, the viscosity of the paste can be controlled.

In the screen printing apparatus according to claim 3, since the second variable mechanism that changes the degree of bending of the bending portion is provided, the viscosity of the paste can be controlled.

In the squeegee according to the fourth aspect, since the curved portion and the straight portion are provided, the rolling of the paste is promoted, and the viscosity of the paste supplied onto the screen plate can be adjusted.

1 is a side view of a screen printing apparatus according to a first embodiment of the present invention. (A), (B) is explanatory drawing which shows the deformation | transformation of the squeegee of the screen printing apparatus. It is a perspective view of the squeegee and the 1st variable mechanism of the screen printing apparatus. It is explanatory drawing which shows fixation of the squeegee of the screen printing apparatus. (A), (B) is explanatory drawing which shows the deformation | transformation of the squeegee by the 1st variable mechanism of the squeegee of the screen printing apparatus. It is explanatory drawing which shows the rolling of the paste scraped off with the squeegee of the screen printing apparatus. (A), (B) is explanatory drawing which shows a mode that the squeegee provided in the screen printing apparatus which concerns on the 2nd Embodiment of this invention deform | transforms. It is a perspective view of the squeegee and the 2nd variable mechanism of the screen printing apparatus. (A), (B) is explanatory drawing which shows a deformation | transformation of the squeegee by the 2nd variable mechanism of the squeegee of the screen printing apparatus.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.

As shown in FIG. 1, the screen printing apparatus 10 according to the first embodiment of the present invention includes a squeegee 11, a scraper 12, and a paste supply unit 13. The screen printing apparatus 10 is supplied from the paste supply unit 13 while moving the scraper 12 in one direction on a screen plate 15 in which an opening (not shown) having the same shape as the electrode print pattern is formed. Spread the paste on the screen plate 15. Then, the screen printing apparatus 10 moves the squeegee 11 in the direction opposite to the moving direction of the scraper 12, and causes the spread paste to adhere to the surface of the printing medium 16 disposed under the screen plate 15 for printing. Can do. As an example of the substrate 16 to be printed, a rectangular silicon wafer for solar cell can be cited.
Hereinafter, the paste supply unit 13, the scraper 12, and the squeegee 11 will be described in order.

The paste supply unit 13 includes a paste tank 20 and a viscosity adjusting mechanism 21. The paste supply unit (paste tank 20 and viscosity adjusting mechanism 21) 13 is provided on a moving table 25 that is driven by a chain 26 to reciprocate. Here, the viscosity adjusting mechanism 21 is provided at the tip of the shaft of the air cylinder 31 that moves in the vertical direction, and is connected to the moving table 25 via the air cylinder 31.

The paste tank 20 is provided with a first stirring blade (not shown) for storing the paste and adjusting its viscosity.

The viscosity adjusting mechanism 21 receives the paste from the paste tank 20 via a tube (not shown by a one-dot chain line in FIG. 1), and stirs the received paste with a second stirring blade (not shown). The viscosity of the paste can be reduced.
The paste is supplied from the paste tank 20 through a viscosity adjusting mechanism 21 to a supply port (not shown) provided above the scraper 12.

The scraper 12 is attached to the lower side of the supply port so that the paste flowing out from the supply port can be guided to the screen plate 15 to be expanded and tilted backward with respect to the moving direction when the scraper 12 expands the paste. Yes.
The scraper 12 is provided below the viscosity adjusting mechanism 21 and is moved up and down together with the viscosity adjusting mechanism 21 by an air cylinder 31. Accordingly, the scraper 12 reciprocates together with the paste supply unit 13.

The squeegee 11 is provided forward in the moving direction when the scraper 12 spreads the paste. The base of the squeegee 11 is held by a holder 45. The holder 45 is connected to the tip of the shaft of the air cylinder 39 that moves in the vertical direction and moves up and down. The air cylinder 39 is connected to the movable table 25. Therefore, the squeegee 11 can move up and down, and reciprocates together with the paste supply unit 13 and the scraper 12. The material of the squeegee 11 is hard rubber, for example.

Next, the squeegee 11 will be described in more detail.
As shown in FIG. 2A, the squeegee 11 is curved in a plan view and a curved portion 40 that curves inward (concave side) in a moving direction when sliding on the screen plate 15 in a plan view. And a straight portion 41 extending outward from the both ends of the portion 40 linearly. In this regard, the squeegee 11 is different from a squeegee that is curved from one end to the other end.
As shown in FIG. 2B, the straight portion 41 of the squeegee 11 can rotate within a predetermined angle range around the joint portion with the bending portion 40. That is, the squeegee 11 is configured so that the angle θ formed by the bending portion 40 and the straight portion 41 is variable, and can be deformed.

Specifically, as shown in FIG. 3, the squeegee 11 has a curved shape in which a flat plate member is bent at the center in the longitudinal direction. A chamfer CH is applied to the lower corner of the moving direction when sliding with respect to the screen plate 15 (that is, the surface on the side where the paste is scraped off). The chamfering angle of the chamfer CH is provided with respect to the screen plate 15 in a range of, for example, 70 degrees ± 20 degrees.
As shown in FIG. 4, the squeegee 11 is held by holder members 45 a and 45 b constituting the holder 45 being clamped with bolts sandwiching the upper part of the both ends of the squeegee 11 in the left-right direction (upper part of the linear part 41). . By attaching the holder 45 to the first variable mechanism 50, the angle θ formed by the bending portion 40 and the straight portion 41 is variable.

As shown in FIG. 3, the first variable mechanism 50 includes a base member 51, a hinge portion 52, and an angle adjusting screw 53.
The base member 51 is a plate-like member. The base member 51 is fixed to the tip of the shaft of the air cylinder 39 (see FIG. 1).
The hinge portion 52 is configured by fitting a pin protruding downward from the base member 51 into a hole 55 (see FIG. 4) formed in the upper portion of the holder member 45a. The pin is prevented from coming off so as not to come off.
The angle adjusting screw 53 passes through a curved long hole 57 formed on the base member 51 along an arc having a radius R with the pin of the hinge portion 52 as the center, and a screw hole 58 formed in the holder member 45a. Inserted into.
As shown in FIG. 5 (B), when the angle adjusting screw 53 shown in FIG. 5 (A) is loosened, the holder 45 can be rotated around the hinge portion 52, so that the bending portion 40 and the straight portion 41 are separated. The formed angle θ is variable. By tightening the angle adjusting screw 53, the angle θ formed by the bending portion 40 and the straight portion 41 is fixed.

Next, the operation of the squeegee 11 will be described.
The squeegee 11 is fixed so that the attack angle is substantially 90 degrees. In other words, the squeegee 11 is fixed without tilting forward or backward with respect to the moving direction. However, the chamfer CH (see FIGS. 3 and 4) formed at the lower corner of the squeegee 11 acts on the paste as being equivalent to the attack angle. Note that “substantially 90 degrees” means that an attachment error or the like of the squeegee 11 is allowed. Therefore, the actual attack angle may be 97 degrees to 103 degrees, for example.

When the moving table 25 moves with the shaft of the air cylinder 39 lowered, the squeegee 11 can scrape off the paste formed on the screen plate 15 while pressing it with the tip of the squeegee 11.
The paste existing between the front portion (especially the chamfered portion) of the squeegee 11 and the screen plate 15 is rolled by forming a circulating flow in the vertical direction. In addition, as shown in FIG. 6, the paste gathered by the straight portion 41 of the squeegee 11 is along the inside of the squeegee 11 in the vicinity of the straight portion 41, and in the moving direction ( It rolls away in the scraping direction) and flows again toward the end of the linear portion 41. Accordingly, the flow is promoted more than when a conventional flat squeegee is used, and the viscosity of the paste is quickly reduced. That is, the viscosity of the paste supplied on the screen plate 15 can be adjusted.

The paste with reduced viscosity is filled in the opening, and when the squeegee 11 passes over the opening, a shearing force is applied by pressing the squeegee 11 and the viscosity is further reduced. As a result, the paste in the opening adheres to the surface of the printing medium 16 disposed under the screen plate 15.
Then, after the squeegee 11 passes over the opening, the paste attached to the surface of the printing medium 16 is allowed to stand and the viscosity of the paste increases. For this reason, when the screen plate 15 is separated from the surface of the printing medium 16, the paste attached to the surface of the printing medium 16 does not adhere to the screen plate 15 and peel off. Further, the paste does not flow on the surface of the printing medium 16. Accordingly, the print quality is stabilized.

Thus, in the screen printing apparatus 10 according to the present embodiment, the degree of paste rolling changes by changing the angle θ formed by the curved portion 40 and the linear portion 41, so that the viscosity can be controlled. it can. In addition, most of the paste rolls on the inner side (concave side) of the squeegee 11 and does not flow out of the squeegee 11, so that it is not necessary to supply more paste than necessary and waste of the paste can be suppressed.
Furthermore, the first variable mechanism 50 can easily change the angle θ formed by the bending portion 40 and the straight portion 41, so there is no need to prepare a plurality of squeegees having different angles θ.

Next, a screen printing apparatus according to the second embodiment of the present invention will be described. The same components as those of the screen printing apparatus 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

As shown in FIG. 7A, in the present embodiment, the squeegee 11 has a curved portion 40 that curves inward in a moving direction when sliding on the screen plate 15 in plan view, and a plan view. And a linear portion 41 extending linearly outward from both ends of the curved portion.
As shown in FIG. 7B, the bending portion 40 of the squeegee 11 is configured such that the bending degree R is variable at the central portion.

Specifically, as shown in FIG. 8, the squeegee 11 has a curved shape in which a flat plate member is bent at the center in the longitudinal direction. A chamfer CH is applied to the lower corner of the moving direction when sliding with respect to the screen plate 15.
As shown in FIG. 4, the squeegee 11 is held by sandwiching the upper portions at the left and right ends of the squeegee 11 (upper portions of the straight portions 41) by holder members 45 a and 45 b constituting the holder 45. By attaching to the variable mechanism 80, the bending degree R of the bending portion 40 becomes variable.

As shown in FIG. 8, the second variable mechanism 80 includes a base member 81, an angle adjustment knob 82, a feed screw 83, and a moving member 84.
The base member 81 is a flat member.
The feed screw 83 is connected to the center of rotation of the angle adjustment knob 82 at the center and is rotatably supported by the support member 85 at both ends. Accordingly, the feed screw 83 rotates when the operator rotates the angle adjustment knob 82. The feed screw 83 is threaded in opposite directions on the right and left sides of the angle adjustment knob 82.
The moving member 84 moves along a guide (not shown) provided in a rectangular hole 88 formed in the base member 81. A female screw corresponding to the feed screw 83 is formed on the moving member 84. The moving member 84 is provided with a pin (not shown) protruding downward. This pin is rotatably inserted into a hole 55 (see FIG. 4) formed in the upper part of the holder member 45a. This pin is prevented from coming off so as not to come off.

When the angle adjustment knob 82 is rotated, the feed screw 83 is rotated as described above. When the feed screw 83 rotates, the moving members 84 move toward the outside of the rotation axis of the feed screw 83, respectively. Then, for example, as shown in FIGS. 9A and 9B, the distance between the pins provided on the moving member 84 changes from the distance D1 to the distance D2, and the bending degree R of the bending portion 40 is changed. .

In this way, by changing the bending degree R of the bending portion 40, the degree of paste rolling changes, so that the viscosity can be controlled.
In addition, most of the paste rolls on the inner side (concave side) of the squeegee 11 and does not flow out of the squeegee 11, so that it is not necessary to supply more paste than necessary and waste of the paste can be suppressed.
Furthermore, since the bending degree R of the bending portion 40 can be easily changed by the second variable mechanism 80, it is not necessary to prepare a plurality of squeegees having different bending degrees R.

In addition, this invention is not limited to the above-mentioned embodiment, The change in the range which does not change the summary of this invention is possible. For example, a case where the present invention is configured by combining some or all of the above-described embodiments and modifications is also included in the technical scope of the present invention.

As long as the angle θ formed by the bending portion 40 and the linear portion 41 is variable, the first variable mechanism 50 is not limited to the first embodiment.
Further, as long as the bending degree R of the bending portion 40 is variable, the second variable mechanism 80 is not limited to the second embodiment.
In addition, it is obvious that the screen printing apparatus can be applied to a printing medium other than a silicon wafer for solar cells as long as the printing paste is a non-Newtonian fluid.

10: Screen printing device, 11: Squeegee, 12: Scraper, 13: Paste supply unit, 15: Screen plate, 16: Printed material, 20: Paste tank, 21: Viscosity adjusting mechanism, 25: Moving table, 26: Chain , 31: air cylinder, 39: air cylinder, 40: curved portion, 41: linear portion, 45: holder, 45a, 45b: holder member, 50: first variable mechanism, 51: base member, 52: hinge portion, 53: Angle adjusting screw, 55: Hole, 57: Long hole, 58: Screw hole, 80: Second variable mechanism, 81: Base member, 82: Angle adjusting knob, 83: Feed screw, 84: Moving member, 85: Support member, 88: Hole

Claims (4)

A screen printing apparatus having a squeegee for scraping off non-Newtonian fluid paste,
The squeegee is attached so that an attack angle is substantially 90 degrees, and a curved portion that curves inward in a scraping direction for scraping the paste in plan view, and a curved portion of the curved portion in plan view. A straight portion extending outwardly in a straight line from both ends,
The screen printing apparatus, wherein a lower corner portion of the squeegee on the scraping direction side is chamfered. The screen printing apparatus according to claim 1, further comprising a first variable mechanism that varies an angle formed by the curved portion and the linear portion. 3. The screen printing apparatus according to claim 2, further comprising a second variable mechanism that changes a degree of bending of the bending portion instead of the first variable mechanism. A squeegee that scrapes off non-Newtonian fluid paste,
A curved portion that curves inward in the scraping direction to scrape off the paste in plan view;
A straight portion extending outwardly in a straight line from both ends of the curved portion in plan view,
A squeegee, wherein a lower corner portion of the scraping direction side is chamfered.

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