Screen printing plate design for solving cell piece silk-screen printing chamfer missing and cell piece

Abstract

The invention discloses a screen printing plate design for solving the problem of cell silk-screen printing chamfer missing and a cell, and belongs to the technical field of solar cell processing. A pattern for printing a chamfer grid line in a chamfer area of the cell is set to be two wavy lines with the same distance and phase; and the printing loss of the chamfering grid line is eliminated by increasing the printing contact area. According to the invention, the arc curve design of the chamfer area of the printing pattern is changed into the arc wavy line design, and the wavy line design can increase the printing contact area, so that the printing ink permeability is smoother, and the problem of printing missing at the chamfer position is solved. And the missing rate of the printing chamfer position is reduced, and the battery printing yield is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of solar cell processing, and particularly relates to a screen design and a solar cell for solving the problem of missing chamfers in screen printing of solar cells. Background Art

[0002] Topcon solar cell screen printing uses the basic principle that the mesh holes in the graphic part of the screen are permeable to ink, while the mesh holes in the non-graphic part are impermeable to ink. The screen is squeezed by a squeegee to elastically deform and then the slurry is leaked onto the material to be printed. It has high requirements for appearance. The silver paste grid lines must be printed on the silicon substrate in accordance with the designed pattern, complete and clear, without any missing parts, to ensure its normal performance.

[0003] The final step in the Topcon solar photovoltaic cell production process is screen printing. Screen printing utilizes the principle that the mesh holes in the image area of ​​the screen are permeable to ink, while the non-image areas are impermeable. A squeegee is used to squeeze the screen, causing it to deform elastically, and then deposit the slurry onto the cells. Screen printing requires high aesthetic standards; all graphics must be printed completely, clearly, and without any missing parts onto the silicon substrate. High-temperature sintering then ensures that the silver paste grid lines form a good physical and electrical ohmic contact with the silicon substrate. After testing and sorting, the finished cells are ready.

[0004] In the existing technology, various printing defects may occur during mass production of screen printing, especially in the non-chamfered areas of the graphics. Common defects include broken grids, nodes, uneven thickness, offset, and leakage. Broken grids are mainly caused by blocked holes, which can be solved by wiping the screen in the actual production process; nodes and uneven thickness are mainly caused by the presence of agglomerated particles in the silver paste used for solar cell printing. The large particles can be removed by filtering and grinding the silver paste, and the ink permeability of the silver paste is completely improved. The problems of nodes and uneven thickness can be solved; offset is mainly caused by alignment errors in the X, Y, and Z axes of the printing machine during long-term printing, which can be solved by compensating for the offset of the X, Y, and Z axes of the machine; leakage is mainly caused by holes in the film layer of the printing screen, which leaks silver paste through the holes to the surface of the silicon substrate. It can be solved by repairing the holes or replacing the printing screen. However, in the actual mass production of solar cells, the screen printing process is very difficult because the chamfered areas have a certain angle and are not printed vertically in a straight line. It is easy for the chamfer lines to be missing during the printing process, resulting in poor appearance, which seriously affects the product qualification rate and its power generation performance at the power station end.

[0005] Therefore, there is an urgent need for a screen design and a solar cell that can solve the problem of missing chamfers in screen printing of solar cells. Summary of the Invention

[0006] In order to overcome the problems in the prior art that the chamfered area is difficult to print during the screen printing process, and the chamfer line is easily missing, resulting in poor appearance, which seriously affects the product qualification rate and its power generation performance at the power station end, the present invention provides a screen design and a solar cell that solves the problem of missing chamfers in screen printing of solar cells, as follows:

[0007] A screen design for solving the problem of missing chamfers in screen printing of solar cells. The pattern of printed chamfer lines in the chamfered area of ​​the solar cell is set as two wavy lines with the same spacing and phase. The missing chamfer lines are eliminated by increasing the printing contact area.

[0008] This invention addresses the issue of missing prints at chamfered corners by replacing the curved chamfered area with a wavy curved line. This wavy line significantly increases the print contact area, allowing for smoother ink penetration. This method significantly reduces the missing print rate at chamfered corners and significantly improves the yield rate of battery printing.

[0009] Furthermore, the wave height of the wavy line is 0.01-0.05 mm, the angle is 2-3°, the wavelength is 0.15-0.25 mm, and the length of the chamfered grid line is 5-6 mm.

[0010] Furthermore, the wave height of the wavy line is 0.03 mm, the angle is 2.08°, and the wavelength is 0.18 mm.

[0011] Furthermore, the distance between the two wavy lines is 15-20 nm.

[0012] The present application also provides a screen printing method for a cell, which adopts the above-mentioned screen design and includes the following steps:

[0013] Step 1: Print three busbars and chamfered grid lines on the surface of the solar cell according to the screen design to form a complete busbar and chamfered grid line;

[0014] Step 2: drying and sintering the battery cells;

[0015] Step 3: Perform the fourth printing according to the screen design, and apply printing pressure with a scraper to form complete fine grid lines;

[0016] Step 4: Dry and sinter the battery cell to fuse the chamfered grid lines with the battery cell to form complete silver paste grid lines.

[0017] Furthermore, in step three, the printing pressure is 40-60 N, the screen pitch is 1.8-2.5 mm, and the scraper depth is 1.7-2.0 mm.

[0018] Furthermore, the chamfered grid lines completely cover the chamfered area of ​​the cell and extend to the main grid line connection area.

[0019] The present application also provides a solar cell, wherein the chamfered grid lines in the chamfered area of ​​the cell are printed according to the screen design according to claim 1, and the chamfered grid lines completely cover the chamfered area without any printing defects.

[0020] The beneficial effects produced by the technical solution of the present invention are as follows:

[0021] (1) This invention solves the problem of missing prints at the chamfered corners by changing the chamfered corner design from an arc-shaped curve to an arc-shaped wavy line design. This wavy line design can greatly increase the printing contact area and make the printing ink permeability smoother, thereby solving the problem of missing prints at the chamfered corners. By implementing this method, the missing print rate at the chamfered corners is greatly reduced, and the battery printing yield rate is significantly improved.

[0022] (2) The graphics in the chamfered area are designed to be wavy to increase the printing contact area. After the wavy line design, the angle changes continuously during the printing process. The chamfered wavy line design makes the printing smoother and more ink-permeable, thereby solving the problem of missing chamfered printing and the problem of broken printing lines, thereby improving the printing yield rate. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] This embodiment changes the chamfered area of ​​the printed pattern from an arc curve design to an arc wavy line design. This wavy line design can greatly increase the printing contact area, making the printing ink permeability smoother, thereby solving the problem of missing printing at the chamfered position. The specific implementation method is as follows:

[0025] A screen design for solving the problem of missing chamfers in screen printing of solar cells. The pattern of printed chamfer lines in the chamfered area of ​​the solar cell is set as two wavy lines with the same spacing and phase. The missing chamfer lines are eliminated by increasing the printing contact area.

[0026] Here, by designing the grid lines in the chamfered area as two wavy lines with the same phase and uniform spacing, the continuous undulation of the wavy structure allows for dynamic conformation to the chamfered surface of the cell during screen printing. This design significantly increases the contact area between the printing paste and the chamfered area of ​​the cell, avoiding the localized poor contact caused by the curvature of the chamfered surface, which is common with traditional straight grid lines. This eliminates grid line printing defects (such as broken lines and virtual printing) in the chamfered area and improves grid line integrity.

[0027] As a preferred embodiment, the wave height of the wavy line is 0.01-0.05 mm, the angle is 2-3°, the wavelength is 0.15-0.25 mm, and the length of the chamfered grid line is 5-6 mm.

[0028] Here, the limitation of wave height can control the fluctuation amplitude of the wave line, avoiding the obstruction of slurry flow due to excessive wave height or the inability to form effective contact due to too small wave height; the limitation of angle optimizes the adhesion of slurry on the surface of wavy line through a small tilt angle, reducing the burrs on the edge of grid line after printing; the limitation of wavelength matches the mesh size of screen and slurry fluidity, ensuring that the wavy line pattern can release slurry evenly during printing; the limitation of the length of chamfered grid line can cover the common chamfer area size of battery cell, ensuring the integrity of grid line extending to the main grid line connection area.

[0029] As a preferred embodiment, the wave height of the wavy line is 0.03 mm, the angle is 2.08°, and the wavelength is 0.18 mm.

[0030] Here, the best fit between the wavy lines and the chamfered surface is achieved through the optimized combination of specific parameters. This parameter combination may be verified through experiments as the optimal solution for balancing slurry adhesion, printing resolution and production efficiency.

[0031] As a preferred embodiment, the distance between the two wavy lines is 15-20 nm.

[0032] If the spacing is too small, the paste may merge to form thick lines, reducing the grid line resolution; if the spacing is too large, the double-line redundancy design cannot compensate for the defects of single-line printing. This spacing range ensures the independence of the two lines while enhancing the overall conductivity through the superposition effect.

[0033] This embodiment also provides a screen printing method for a cell, which adopts the above-mentioned screen design and includes the following steps:

[0034] Step 1: Print three busbars and chamfered grid lines on the surface of the solar cell according to the screen design to form a complete busbar and chamfered grid line;

[0035] Step 2: drying and sintering the battery cells;

[0036] Step 3: Perform the fourth printing according to the screen design, and apply printing pressure with a scraper to form complete fine grid lines;

[0037] Step 4: Dry and sinter the battery cell to fuse the chamfered grid lines with the battery cell to form complete silver paste grid lines.

[0038] As a preferred embodiment, in step three, the printing pressure is 40-60N, the screen pitch is 1.8-2.5mm, and the scraper depth is 1.7-2.0mm.

[0039] Printing pressure balances slurry permeability and screen life. Too low a pressure results in insufficient slurry transfer, while too high a pressure accelerates screen wear. Screen spacing controls screen rebound speed, preventing smearing from too small a spacing or insufficient slurry penetration from too large a spacing. Squeegee depth regulates slurry fill. Too shallow a depth results in insufficient grid line height, while too deep a depth increases the risk of line breakage.

[0040] As a preferred embodiment, the chamfered grid lines completely cover the chamfered area of ​​the cell and extend to the main grid line connection area.

[0041] Here, the chamfered grid lines completely cover the chamfered area and extend to the main grid line connection area, which can eliminate the electric field concentration effect at the chamfer edge and reduce local composite losses; ensure the electrical connection between the main grid line and the fine grid line in the chamfer area, avoiding the interruption of the current transmission path due to the missing grid line; improve the mechanical strength of the battery cell edge and reduce the risk of hidden cracks.

[0042] This embodiment further provides a solar cell, wherein chamfered grid lines in a chamfered area of ​​the cell are printed according to the screen design according to claim 1, and the chamfered grid lines completely cover the chamfered area without any printing defects.

[0043] Example 1

[0044] A solar cell produced by a screen printing method comprises the following steps:

[0045] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 166 mm, an angle of 2.08°, a wave height of 0.03 mm, and a wavelength of 0.18 mm.

[0046] Step 2: After drying and sintering the cell printed in step 1, a fourth printing is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 45N, the screen pitch is 1.8mm, and the scraper depth is 1.7mm.

[0047] Step 3: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 5.631mm.

[0048] Example 2

[0049] A solar cell produced by a screen printing method comprises the following steps:

[0050] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 150 mm, an angle of 2.6°, a wave height of 0.04 mm, and a wavelength of 0.25 mm.

[0051] Step 2: After drying and sintering the cell printed in step 1, a fourth printing is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 60N, the screen pitch is 2.5mm, and the scraper depth is 1.7mm.

[0052] Step three: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 6.012mm.

[0053] Example 3

[0054] A solar cell produced by a screen printing method comprises the following steps:

[0055] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 180 mm, an angle of 2°, a wave height of 0.02 mm, and a wavelength of 0.25 mm.

[0056] Step 2: After drying and sintering the cell printed in step 1, a fourth printing is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 50N, the mesh pitch is 2.0mm, and the scraper depth is 2.0mm.

[0057] Step 3: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 5.924mm.

[0058] Example 4

[0059] A solar cell produced by a screen printing method comprises the following steps:

[0060] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 166 mm, an angle of 2.5°, a wave height of 0.04 mm, and a wavelength of 0.19 mm.

[0061] Step 2: After drying and sintering the cell printed in step 1, a fourth printing is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 60N, the screen pitch is 2.2mm, and the scraper depth is 1.9mm.

[0062] Step 3: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 5.458mm.

[0063] Example 5

[0064] A solar cell produced by a screen printing method comprises the following steps:

[0065] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 167 mm, an angle of 2.1°, a wave height of 0.05 mm, and a wavelength of 0.25 mm.

[0066] Step 2: After drying and sintering the cell printed in step 1, a fourth printing is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 50N, the mesh pitch is 2.3mm, and the scraper depth is 2.0mm.

[0067] Step 3: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 5.631mm.

[0068] Example 6

[0069] A solar cell produced by a screen printing method comprises the following steps:

[0070] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 175 mm, an angle of 2.6°, a wave height of 0.04 mm, and a wavelength of 0.24 mm.

[0071] Step 2: After drying and sintering the cell printed in step 1, a fourth printing is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 55N, the screen pitch is 2.4mm, and the scraper depth is 1.9mm.

[0072] Step 3: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 5.635mm.

[0073] Comparative Example 1

[0074] A solar cell produced by a screen printing method comprises the following steps:

[0075] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 147 mm, an angle of 3.1°, a wave height of 0.07 mm, and a wavelength of 0.27 mm.

[0076] Step 2: After drying and sintering the cell printed in step 1, a fourth printing step is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 35N, the mesh pitch is 1.7mm, and the scraper depth is 2.1mm.

[0077] Step three: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 6.129mm.

[0078] Comparative Example 2

[0079] A solar cell produced by a screen printing method comprises the following steps:

[0080] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 138 mm, an angle of 3.5°, a wave height of 0.09 mm, and a wavelength of 0.28 mm.

[0081] Step 2: After drying and sintering the cell printed in step 1, a fourth printing step is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 38N, the screen pitch is 1.6mm, and the scraper depth is 2.2mm.

[0082] Step 3: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 6.135mm.

[0083] Comparative Example 3

[0084] A solar cell produced by a screen printing method comprises the following steps:

[0085] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 129 mm, an angle of 3.4°, a wave height of 0.06 mm, and a wavelength of 0.29 mm.

[0086] Step 2: After drying and sintering the cell printed in step 1, a fourth printing process is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 37N, the screen pitch is 1.5mm, and the scraper depth is 2.3mm.

[0087] Step 3: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 6.229mm.

[0088] Comparative Example 4

[0089] A solar cell produced by a screen printing method comprises the following steps:

[0090] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 133 mm, an angle of 3.3°, a wave height of 0.06 mm, and a wavelength of 0.6 mm.

[0091] Step 2: After drying and sintering the cell printed in step 1, a fourth printing is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 25N, the screen pitch is 3mm, and the scraper depth is 2.2mm.

[0092] Step 3: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 6.140mm.

[0093] Comparative Example 5

[0094] A solar cell produced by a screen printing method comprises the following steps:

[0095] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines. The chamfered grid lines are wavy lines with a radius of 185 mm, an angle of 3.6°, a wave height of 0.07 mm, and a wavelength of 0.7 mm.

[0096] Step 2: After drying and sintering the cell printed in step 1, a fourth printing is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 70N, the mesh pitch is 3.6mm, and the scraper depth is 1.5mm.

[0097] Step 3: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 4.445mm.

[0098] Comparative Example 6

[0099] A solar cell produced by a screen printing method comprises the following steps:

[0100] Step 1: Provide a solar cell, and print three main grid lines and chamfered grid lines on the surface of the solar cell according to the screen to form complete main grid lines and chamfered grid lines, where the chamfered grid lines are straight lines;

[0101] Step 2: After drying and sintering the cell printed in step 1, a fourth printing is performed. A scraper is used to apply printing pressure to form complete fine grid lines. The printing pressure is matched with the wave height of the wave line to achieve ink penetration control. The printing pressure is 45N, the screen pitch is 1.8mm, and the scraper depth is 1.7mm.

[0102] Step 3: Dry and sinter the printed battery cells, melt the chamfered grid lines and the battery cells together to form complete silver paste grid lines. The length of the chamfered grid lines covers the chamfered area of ​​the battery cells and extends to the main grid line connection area. The grid lines are made of silver paste material, completely covering the chamfered area without any printing defects. The length of the chamfered grid lines is 5.631mm.

[0103] The performance of the cells obtained by the methods of the above-mentioned groups 1 to 6 of Examples and groups 1 to 6 of Comparative Examples was tested, and the results are as follows:

[0104] Table 1 Performance test results of the cells prepared in each embodiment and comparative example

[0105] project Radius (mm) Angle (°) wave height Wavelength (mm) Printing pressure (N) Grid spacing (mm) Scraper depth (mm) Chamfered grid line length (mm) Chamfer missing rate (%) Improvement rate of qualified products (%) Example 1 166 2.08 0.03 0.18 45 1.8 1.7 5.631 0 0.3 Example 2 150 2.6 0.04 0.25 60 2.5 1.7 5.812 0 0.4 Example 3 180 2 0.02 0.25 50 2.0 2.0 5.924 0 0.3 Example 4 166 2.5 0.04 0.19 60 2.2 1.9 5.458 0 0.5 Example 5 167 2.1 0.05 0.25 50 2.3 2.0 5.631 0 0.5 Example 6 175 2.6 0.04 0.24 55 2.4 1.9 5.635 0 0.4 Comparative Example 1 147 3.1 0.07 0.27 35 1.7 2.1 6.129 0.4 0 Comparative Example 2 138 3.5 0.09 0.28 38 1.6 2.2 6.135 0.5 0 Comparative Example 3 129 3.4 0.06 0.29 37 1.5 2.3 6.134 0.4 0 Comparative Example 4 133 3.3 0.06 0.6 25 3.0 2.2 6.133 0.4 0 Comparative Example 5 185 3.6 0.07 0.7 70 3.6 1.5 4.445 0.6 0 Comparative Example 6 0 0 0 0 45 1.8 1.7 5.631 0.5 0

[0106] As shown in Table 1, Examples 1 to 6 all use a wavy graphic design at the chamfer to increase the printing contact area. After the wavy line design, the angle changes continuously during the printing process. The chamfered wavy line design makes the printing smoother and the ink permeability stronger. The chamfer missing rate during chamfer printing is 0%. Compared with Comparative Examples 1 to 6, the problem of chamfer printing missing can be completely solved.

[0107] The present invention is further described above with the aid of specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the essence and scope of the present invention. Various modifications made to the above embodiments by ordinary technicians in this field after reading this specification are all within the scope of protection of the present invention.

Claims

1. A screen design to solve the problem of missing chamfers in screen printing of solar cells, characterized in that: The pattern of the chamfered grid lines printed in the chamfered area of ​​the cell is set to be two wavy lines with the same spacing and phase, and the defects of the chamfered grid line printing are eliminated by increasing the printing contact area.

2. The screen design for solving the problem of missing chamfers in screen printing of solar cells according to claim 1, characterized in that: The wave height of the wavy line is 0.01-0.05 mm, the angle is 2-3°, the wavelength is 0.15-0.25 mm, and the length of the chamfered grid line is 5-6 mm.

3. The screen design according to claim 2, characterized in that: The wave height of the wavy line is 0.03 mm, the angle is 2.08°, and the wavelength is 0.18 mm.

4. The screen printing method for a battery cell according to claim 1, characterized in that: The distance between the two wavy lines is 15-20 nm.

5. A screen printing method for a battery cell, using the screen design according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Print three busbars and chamfered grid lines on the surface of the solar cell according to the screen design to form a complete busbar and chamfered grid line; Step 2: drying and sintering the battery cells; Step 3: Perform the fourth printing according to the screen design, and apply printing pressure with a scraper to form complete fine grid lines; Step 4: Dry and sinter the battery cell to fuse the chamfered grid lines with the battery cell to form complete silver paste grid lines.

6. The cell screen printing method according to claim 5, characterized in that: In step 3, the printing pressure is 40-60 N, the screen pitch is 1.8-2.5 mm, and the scraper depth is 1.7-2.0 mm.

7. The cell screen printing method according to claim 5, characterized in that: The chamfered grid lines completely cover the chamfered area of ​​the cell and extend to the main grid line connection area.

8. A solar cell, characterized in that: The chamfered grid lines in the chamfered area of ​​the cell are printed according to the screen design according to claim 1 , and the chamfered grid lines completely cover the chamfered area without any printing defects.