TWI650249B - Screen printing method - Google Patents

Abstract

A method for squeezing and screen printing for screen printing. The squeegee includes a squeegee seat and a squeegee. The squeegee portion is fixed to the squeegee seat, and the squeegee portion includes a strip-shaped scraping surface. The scraping surface applies force to the slurry during screen printing. The length of the scraping surface extends in a direction that is not perpendicular to the predetermined moving direction of the squeegee during screen printing.

Description

Screen printing method

This invention relates to a printing technique, and more particularly to a method of squeezing and screen printing for screen printing.

The electrodes of the conventional solar cell are often formed by a screen printing process. The wire of the mesh layer of the screen used in the screen printing process has an angle with the ink drop hole of the barrier layer, and the angle is generally between 22.5 degrees and 30 degrees. Since the mesh of the steel wire can hinder the ink discharge of the ink drop hole, in order to avoid the wire knot of the wire in the ink drop hole of the finger electrode, the opening of the mesh of the mesh layer and the ink drop hole of the finger electrode are The angle between the angles is changed to 0 degrees (or 90 degrees), and the mesh of the mesh is avoided from the ink holes of the finger electrodes. Such a screen is generally referred to as a no-net version. With such a design, the ink discharge smoothness and fine line printability of the printing of the finger electrodes can be improved.

However, when printing with this design, since the steel wire is perpendicular to the direction of travel of the squeegee, when the squeegee pushes the slurry to fill the ink drop hole of the screen, the steel wire blocks the flow of the slurry, resulting in the slurry being unable to be effectively filled. Into the ink drop hole on the other side of the wire. As a result, after printing, the bus bar has a complete row of poorly filled voids in the direction along the wire, causing defects in the appearance of the bus electrode, which in turn leads to a decrease in production yield.

Therefore, an object of the present invention is to provide a method for screen printing and screen printing for screen printing, wherein the length of the scraping surface of the squeegee portion of the squeegee extends in a direction that is not perpendicular to a predetermined moving direction of the squeegee holder, thus When the screen of the screen is perpendicular to the predetermined moving direction of the knife seat, the driving force of the scraping portion on the slurry has an angle component with the moving direction of the knife seat, and the slurry can be changed to fill the ink hole. The flow direction allows the slurry to be filled more smoothly into the ink holes. Therefore, it is possible to avoid the defect that the entire row of ink is poor when the bus electrode is printed, and the yield of the printing process such as the netless screen can be greatly improved.

According to the above object of the present invention, a squeegee for screen printing is proposed. The squeegee includes a squeegee seat and a squeegee. The squeegee portion is fixed to the squeegee seat, and the squeegee portion comprises a long strip-shaped scraping surface, and the scraping surface applies force to the slurry during screen printing, wherein the length of the scraping surface extends and the squeegee seat is determined at the time of screen printing The direction of movement is not vertical.

According to an embodiment of the invention, the squeegee portion is a long strip of uniform thickness, the squeegee portion is fixed to the first surface of the squeegee seat, and the first surface and the squeegee seat are in a predetermined moving direction when screen printing not vertical.

According to an embodiment of the invention, the thickness of the squeegee portion varies along the length of the squeegee, so that the length of the squeegee extends in a direction that is not perpendicular to the predetermined direction of movement of the squeegee during screen printing.

According to an embodiment of the present invention, the angle between the extending direction of the scraping surface and the extending direction of the cutter seat is about 2 to 5 degrees.

According to the above object of the present invention, a method of screen printing is further proposed. In this method, a screen and a screen are used for the screen printing process. The screen includes a mesh layer and a barrier layer. The mesh layer includes a plurality of strips extending in the first direction a wire mesh and a plurality of second mesh wires extending in the second direction, the first direction being perpendicular to the second direction. The barrier layer is attached to the mesh layer. The barrier layer includes a first ink drop hole extending in the first direction and a plurality of second ink drop holes extending in the second direction, the width of the first ink drop hole being greater than the width of each of the second ink drop holes. During the screen printing process, the squeegee moves in the second direction, and the length of the squeegee of the squeezing blade extends in a direction that is not parallel to the first direction.

According to an embodiment of the invention, the second ink drop hole and the second wire are not overlapped.

According to an embodiment of the invention, the squeezing blade comprises a squeegee seat and the squeegee portion is fixed to the squeegee seat. The squeegee portion includes the above-mentioned scraping surface.

According to an embodiment of the invention, the squeegee portion is a long strip of uniform thickness, and the squeegee portion is fixed to the first surface of the squeegee seat, and the first surface and the second direction are not perpendicular.

According to an embodiment of the invention, the thickness of the squeegee portion varies along a direction in which the length of the squeegee extends, such that the length extending direction of the squeegee is not perpendicular to the second direction.

According to an embodiment of the invention, the angle between the extending direction of the scraping surface and the first direction is about 2 to 5 degrees.

100‧‧‧Squeezing knife

110‧‧‧Squeezing knife seat

110e‧‧‧ extending direction

110t‧‧‧ thickness

112‧‧‧ first surface

114‧‧‧ second surface

120‧‧‧Scratch

120t‧‧‧ thickness

122‧‧‧Shaved noodles

122e‧‧‧ Length extension

130‧‧‧Definite moving direction

200‧‧‧Squeezing knife

210‧‧‧Squeeing knife seat

210e‧‧‧Extension direction

210t‧‧‧ thickness

212‧‧‧ first surface

220‧‧‧Scratch Department

220t‧‧‧thickness

222‧‧‧ shaved noodles

222e‧‧‧ Length extension

224‧‧‧ surface

230‧‧‧Definite moving direction

300‧‧‧Squeezing knife

310‧‧‧Squeezing knife seat

312‧‧‧Support

312a‧‧‧ surface

312e‧‧‧Extension direction

314‧‧‧Combination Department

314a‧‧‧ first surface

314t‧‧‧ upper surface

320‧‧‧Scratch

322‧‧‧Shaved noodles

322e‧‧‧ Length extension

330‧‧‧Definite moving direction

400‧‧‧Web Edition

410‧‧‧Mesh layer

412‧‧‧First mesh

414‧‧‧Second mesh

420‧‧‧Block

430‧‧‧First direction

432‧‧‧second direction

440‧‧‧The first ink hole

440w‧‧‧Width

450‧‧‧Second ink hole

450w‧‧‧Width

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; a top view of the squeezing knife; FIG. 2 is a top view of a squeegee for screen printing according to an embodiment of the present invention; FIG. 3A illustrates a squeegee for screen printing according to an embodiment of the present invention. FIG. 3B is a schematic top view showing the squeezing blade shown in FIG. 3A; and FIG. 4 is a schematic view showing a device for performing a screen printing method according to an embodiment of the present invention.

Please refer to FIG. 1 , which is a top view of a squeegee for screen printing according to an embodiment of the present invention. The squeezing knife 100 is used in the screen printing process, especially the screen printing process using the meshless screen design. In some embodiments, the squeegee 100 can include a squeeze seat 110 and a squeegee 120. The squeegee seat 110 is configured to load the squeegee portion 120, and thus the squeegee seat 110 can be a rigid structure. For example, the material of the extrusion block 110 can be a hard plastic or a metal such as stainless steel. The extruder block 110 can be coupled to a drive unit whereby the drive unit can drive the cutter block 110 for screen printing. Each of the squeeze blocks 110 has its preset screen printing direction.

The squeegee portion 120 is fixed to the first surface 112 of the turret seat 110, so that the movement of the squeegee holder 110 can drive the squeegee portion 120. The squeegee portion 120, which may also be referred to as a squeegee blade, is generally of a flexible construction. For example, the material of the squeegee 120 may be rubber. Since the squeegee 120 contacts the stencil and the screen during screen printing, it will wear out after a period of use, so the squeegee 120 is a consumable in the squeegee 100.

As shown in FIG. 1, the squeegee portion 120 includes a scraping surface 122 which is a contact surface of the squeegee 100 and the screen when screen printing. In some exemplary examples, the shaving surface 122 is generally elongated or the shaving surface 122 may be linear. At the time of screen printing, the scraping surface 122 of the squeegee portion 120 applies a force to the printed paste on the screen to push the slurry into the ink smear of the screen. In the present embodiment, the scraping surface 122 has a length extending direction 122e, and the squeegee seat 110 has a predetermined moving direction 130 when the screen printing is performed, wherein the length extending direction 122e of the scraping surface 122 and the predetermined moving direction 130 of the squeegee holder 110 are not vertical. In some examples, the angle between the length extension direction 122e of the scraping surface 122 and the direction of extension 110e of the blade holder 110 is from about 2 degrees to about 5 degrees.

In some exemplary examples, referring again to FIG. 1, the squeegee 120 is an elongated strip having a uniform thickness of 120t, and the thickness 110t of the squeegee 110 extends with the length of the squeegee 122 of the squeegee 120. The direction 122e changes. For example, the thickness 110t of the squeegee seat 110 gradually increases or decreases as the length extending direction 122e of the scraping surface 122. The squeegee seat 110 has a second surface 114 opposite the first surface 112, wherein the first surface 112 is inclined relative to the second surface 114 due to variations in the thickness 110t of the squeegee seat 110. In these examples, the second surface 114 is perpendicular to the predetermined direction of movement 130 of the squeegee seat 110, such that the first surface 112 is not perpendicular to the predetermined direction of movement 130 of the squeegee seat 110, thereby being secured to the first surface 112. The length extending direction 122e of the scraping surface 122 of the squeegee portion 120 is not perpendicular to the predetermined moving direction 130 of the squeegee holder 110.

Since the length extending direction 122e of the scraping surface 122 of the squeegee portion 120 is not perpendicular to the predetermined moving direction 130 of the squeegee holder 110, the screen is When the wire is perpendicular to the predetermined moving direction 130, the squeegeing portion 120 can provide a component of the angle between the slurry and the predetermined moving direction 130, so that the slurry can be smoothly filled into the ink smear of the screen. .

In the present invention, different designs can be utilized to make the length of the scraping surface of the squeegee extending in a direction that is not perpendicular to the intended direction of movement of the squeegee. 2 is a schematic top view of a squeegee for screen printing according to an embodiment of the present invention. In the present embodiment, the squeegee 200 can also include a squeegee holder 210 and a squeegee portion 220, wherein the squeegee portion 220 is fixed to the first surface 212 of the squeegee holder 210. The squeegee holder 210 has its intended direction of movement 230 when screen printing. The squeegee portion 220 includes a scraping surface 222 having a length extending direction 222e. The length extending direction 222e of the scraping surface 222 is not perpendicular to the predetermined moving direction 230 of the squeegee holder 210. In some examples, the longitudinal extension direction 222e of the scraping surface 222 is at an angle of from about 2 degrees to about 5 degrees from the direction of extension 210e of the blade holder 210.

In the present embodiment, the trowel holder 210 has a uniform thickness 210t, and the thickness 220t of the squeegee portion 220 varies along the length extending direction 222e of the scraping surface 222. For example, the thickness 220t of the squeegee portion 220 is gradually increased or decreased along the length extending direction 222e of the scraping surface 222. The squeegee portion 220 has a surface 224 opposite the squeegee 222, and the surface 224 of the squeegee portion 220 is secured to the first surface 212 of the squeegee holder 210 having a uniform thickness 210t. Therefore, the thickness 220t of the squeegee portion 220 is varied such that the squeegee 222 is inclined relative to the surface 224. In this embodiment, the first surface 212 of the squeegee holder 210 is perpendicular to the predetermined moving direction 230 of the squeegee holder 210, so that the surface 224 of the squeegee portion 220 is also perpendicular to the predetermined moving direction 230 of the squeegee holder 210, thus The length extending direction 222e of the scraping surface 222 inclined at the surface 224 is not perpendicular to the predetermined moving direction 230 of the squeegee holder 210.

Please refer to FIG. 3A and FIG. 3B , which are respectively a front view and a top view of a squeeze knife for screen printing according to an embodiment of the present invention. In some embodiments, the squeegee 300 primarily includes a squeegee block 310 and a squeegee 320. The squeegee holder 310 has its intended direction of movement 330 when screen printing. The squeezing seat 310 includes a support portion 312 and a joint portion 314. The support portion 312 is fixed to the upper surface 314t of the joint portion 314. The squeegee portion 320 is fixed to the first surface 314a of the joint portion 314. The squeegee portion 320 includes a scraping surface 322, wherein the scraping surface 322 is substantially elongated and has a length extending direction 322e. In some exemplary examples, the length extension direction 322e of the scraping surface 322 is substantially parallel to the first surface 314a of the joint portion 314.

As shown in FIG. 3B, in the squeezing seat 310, the surface 312a of the support portion 312 is perpendicular to the predetermined moving direction 330 of the squeegee holder 310. The first surface 314a of the joint portion 314 is not perpendicular to the predetermined direction of movement 330 of the knife seat 310. Therefore, the length extending direction 322e of the scraping surface 322 of the squeegee portion 320 fixed to the first surface 314a of the joint portion 314 is not perpendicular to the predetermined moving direction 330 of the squeegee holder 310. In some examples, the surface 312a of the support portion 312 and the first surface 314a of the joint portion 314 are at an angle of about 2 degrees to about 5 degrees, so that the length extending direction 322e of the scraping surface 322 and the support portion 312 of the blade holder 310 are The angle of the extension direction 312e is also about 2 to 5 degrees.

In the present embodiment, when the cutter seat 310 is assembled, the scraping surface 322 of the squeegee portion 320 can be deflected with respect to the support portion 312 at an angle of the joint portion 314, so that the length of the scraping surface 322 extends in the direction 322e. It is not perpendicular to the predetermined moving direction 330 of the squeegee holder 310. Such a design only needs to deflect the joint portion 314 when assembling the knife seat 310 without modifying the screen printing machine, or directly using the current shading portion 320 having a uniform thickness.

Please refer to FIG. 4 , which is a schematic diagram of an apparatus for performing a screen printing method according to an embodiment of the present invention. This embodiment utilizes the above-described squeegee 100 to illustrate the progress of the screen printing method. Of course, the squeegees 200 and 300, or other squeegees whose length extension direction is not perpendicular to the predetermined moving direction of the squeegee seat, can also be used. The screen printing method of the present invention.

In this screen printing method, the squeegee 100 is provided, and the desired screen 400 is prepared, and the squeegee 100 and the screen 400 are used for the screen printing process. In some embodiments, the screen printing process is used to fabricate the bus electrodes and finger electrodes of the solar cell. Of course, the squeegee 100 can also be applied to other screen printing processes, and is not limited to screen printing of electrodes of solar cells. The device design of the squeegee 100 is as described above and will not be described herein.

The screen 400 includes a mesh layer 410 and a barrier layer 420. As shown in FIG. 4, the mesh layer 410 includes a plurality of first mesh wires 412 and a plurality of second mesh wires 414. The first mesh 412 extends in a first direction 430 and the second mesh 414 extends in a second direction 432, thereby being interwoven into a mesh layer 410. In some exemplary examples, the first direction 430 is perpendicular to the second direction 432.

The barrier layer 420 is attached to the mesh layer 410. In some examples, as shown in FIG. 4, the barrier layer 420 includes a first ink drop hole 440 and a plurality of second ink drop holes 450. The first ink drop holes 440 may extend along the first direction 430 , and each of the second ink drop holes 450 may extend along the second direction 432 , that is, the second ink drop holes 450 may be perpendicular to the first ink drop holes 440 . The width of the first ink drop hole 400 440w is greater than the width 450w of each second ink drop hole 450. In these examples, the first ink drop hole 440 is configured to make a bus electrode, and the second ink drop hole 450 is configured to make a finger electrode. Since each solar cell can include a plurality of bus electrodes, the screen 400 can be correspondingly provided with a plurality of first ink holes 440. In some examples, the second ink drop hole 450 does not overlap with the second wire 414, so that no netting occurs in the second ink drop hole 450, so the screen 400 can also be referred to as a netless screen.

The screen printing process uses the squeegee 100 to scrape the slurry on the screen 400, and causes the slurry to fall on the surface of the substrate, such as the surface of the solar panel, via the first ink-removing holes 440 and the second ink-removing holes 450 of the screen 400. Thereby, a paste pattern layer of the bus electrode and the finger electrode is formed on the surface of the substrate. When the screen printing process is performed, the squeegee 100 moves along a predetermined moving direction 130, wherein the predetermined moving direction 130 of the squeegee 100 is the second direction 432 in which the second ink blasting hole 450 extends. Since the squeegee portion 120 of the squeegee 100 is disposed on the first surface 112 of the squeegee base 110, the first surface 112 is not perpendicular to the predetermined moving direction 130 (ie, the second direction 432) of the squeegee 100, and thus the squeegee portion The length extending direction 122e of the scraping surface 122 of 120 is not perpendicular to the second direction 432, and thus the length extending direction 122e of the scraping surface 122 and the first direction 430 are not parallel.

By making the length extending direction 122e of the scraping surface 122 of the squeegee portion 120 of the squeegee 100 not parallel to the first direction 430 extending by the first ink blasting hole 440, that is, not extending parallel to the extending direction of the first mesh 412, The scraping surface 122 has a component force to the driving force of the slurry, and the component has an angle with the second direction 432, so that the flow direction of the slurry filling the first ink removing hole 440 and the second ink removing hole 450 can be changed. Thereby lifting the slurry into the first ink-removing hole 440 and the first The smoothness of the two ink holes 450. Therefore, it is possible to effectively avoid the defects of the entire row of ink filling defects when the bus electrode is printed, and thereby improve the yield of the printing process such as the netless screen.

While the present invention has been described above by way of example, it is not intended to be construed as a limitation of the scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

Claims (6)

A method for screen printing, comprising: performing a screen printing process using a squeegee and a screen, wherein the screen comprises: a mesh layer, the mesh layer comprising a plurality of first lines extending along a first direction a mesh, and a plurality of second meshes extending in a second direction, the first direction being perpendicular to the second direction; and a barrier layer attached to the mesh layer, the barrier layer comprising the first direction a first ink drop hole extending, and a plurality of second ink drop holes extending along the second direction, wherein a width of the first ink drop hole is larger than a width of each of the plurality of second ink drop holes, wherein the screen printing is performed During the process, the squeegee moves in the second direction, and a length extending direction of one of the squeegees of the squeegee is not parallel to the first direction. The method of claim 1, wherein the plurality of second ink holes and the plurality of second wires do not overlap. The method of claim 1, wherein the squeegee comprises: a squeegee holder; and a squeegee portion fixed to the squeegee holder, the squeegee portion comprising the squeegee. The method of claim 3, wherein the squeegee portion is an elongated strip of uniform thickness, the squeegee portion is fixed to a first surface of the squeegee seat, the first surface and the second direction not vertical. The method of claim 3, wherein the thickness of the squeegee varies along a direction in which the length of the squeegee extends, such that the length extension direction of the squeegee is not perpendicular to the second direction. The method of any one of claims 1 to 5, wherein the length extending direction of the scraping surface and the first direction are between 2 and 5 degrees.