Manufacturing method of thinned printing screen

Abstract

The invention provides a manufacturing method of a thinned printing screen plate, which comprises the following steps of: preparing a glass substrate; carrying out scanning modification on a preset graphic area on the first side surface of the glass substrate by using femtosecond laser pulse, wherein the depth of laser modification is smaller than the thickness of the glass substrate; cleaning the glass substrate, and removing the modified glass in a laser irradiation area; carrying out scanning modification on an area corresponding to the preset pattern on the second side surface of the glass substrate by using femtosecond laser pulse so as to modify the residual glass after the first modification in the thickness direction of the glass substrate; and cleaning the glass substrate, and removing the modified glass in the second laser irradiation area. According to the invention, the femtosecond laser is used for modifying the glass substrate from different sides twice, so that the width of the grid line can be greatly reduced, the height of the grid line can be increased, the shading of the grid line can be reduced, the short current is improved, and the efficiency of the battery piece is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of screen printing templates, and in particular to a method for manufacturing a fine-line printing screen plate. Background Art

[0002] With the development of the photovoltaic industry, TOPCon cells have gradually become the mainstream of crystalline silicon cells due to their ultra-high theoretical efficiency limit (28.7%), excellent back surface tunneling oxide layer passivation contact technology, low temperature, low coefficient, and high bifacial ratio. However, the market not only requires higher conversion efficiency, but also lower cost is becoming increasingly important. Currently, the electrode grid lines are mainly realized by screen printing. The existing printing templates are mainly screen mesh + PI film composite screen plates. Affected by the current processing technology - waste discharge during the laser process of the PI film material, rough ablation at the opening edge after laser processing, and the laser opening taper, the minimum printing width of the screen mesh + PI film composite screen plate can only reach 15μm - 20μm, and while the printing limit height is 8 - 9μm, the undulation of the grid lines is 3μm - 5μm, and the corresponding effective height is 3μm - 6μm. This not only results in a large consumption of silver paste, but also cannot meet the increasing demand for the grid line line type.

[0003] Therefore, it is necessary to design a method for manufacturing a fine-line printing screen plate to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for manufacturing a fine-line printing screen plate. Through the present invention, the width of the grid lines can be significantly reduced, thereby reducing the grid line light shielding, improving the short-circuit current, increasing the grid line height, and further significantly increasing the aspect ratio of the grid line height and width. Moreover, the undulation of the grid line printing can be reduced, thereby improving the filling.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: A method for manufacturing a fine-line printing screen plate, which includes:

[0006] S1: Prepare a glass substrate;

[0007] S2: First laser modification: Use femtosecond laser pulses to scan and modify a preset graphic area on the first side of the glass substrate. The depth of the laser modification is less than the thickness of the glass substrate;

[0008] S3: Clean the glass substrate to remove the modified glass in the area irradiated by the laser in S2;

[0009] S4: Second laser modification: Use femtosecond laser pulses to scan and modify the area corresponding to the preset graphic on the second side of the glass substrate to modify the remaining glass after the modification in S2 in the thickness direction of the glass substrate;

[0010] S5: Clean the glass substrate to remove the modified glass in the femtosecond laser irradiated area.

[0011] As a further improved technical solution of the present invention, the thickness of the glass substrate is 50 - 80 μm.

[0012] As a further improved technical solution of the present invention, in step S2, the processing depth of the femtosecond laser is 40 μm - 60 μm.

[0013] As a further improved technical solution of the present invention, in step S2, the wavelength of the femtosecond laser is 515 nm or 1030 nm, the pulse is 200 fs - 500 fs, the repetition frequency is 100 KHz - 1 MHz, the single pulse energy is 10 - 50 μJ, and the scanning speed is 0.2 - 0.5 m / s.

[0014] As a further improved technical solution of the present invention, the S3 step includes:

[0015] S31: Clean with a cleaning solution. The formula of the cleaning solution is 1 - 3% hydrofluoric acid, 3 - 5% nitric acid, 0.1 - 1% polyoxyethylene octylphenol ether, 0.1 - 1% disodium EDTA, and 90 - 95% deionized water. The cleaning temperature is 25°C - 40°C, the ultrasonic frequency for cleaning is 30 - 50 KHz, the ultrasonic power is 30 - 60 W, and the cleaning time is 2 min - 3 min;

[0016] In this step, hydrofluoric acid is responsible for cleaning the modified glass area. The corrosion rate of hydrofluoric acid in the modified area and the unmodified area differs by 100 times. Therefore, low-concentration hydrofluoric acid can selectively remove the glass in the modified area with little impact on the unmodified area. The nitric acid solution dissolves metal ions in the glass. Polyoxyethylene octylphenol ether mainly reduces the surface tension and improves the wettability of the corrosive solution to the microporous structure. Disodium EDTA complexes metal ions (such as Al3+ and Fe3+) to prevent metal ions oxidized by nitric acid from forming precipitates and adhering to the glass surface, affecting further reactions;

[0017] S32: Soak and clean with deionized water. The cleaning temperature is 50°C - 80°C, the ultrasonic frequency for cleaning is 30 - 50 KHz, the ultrasonic power is 30 - 60 W, and the cleaning time is 2 min - 3 min.

[0018] As a further improved technical solution of the present invention, in the S31 step, the formula of the cleaning solution is 1.5% hydrofluoric acid, 4% nitric acid, 0.3% polyoxyethylene octylphenol ether, 0.5% disodium EDTA, and 93.7% deionized water.

[0019] As a further improved technical solution of the present invention, the S4 step includes:

[0020] S41. Cleaning with a cleaning solution. The formula of the cleaning solution is 1 - 3% hydrofluoric acid, 3 - 5% nitric acid, 0.1 - 1% polyoxyethylene octylphenol ether, 0.1 - 1% disodium EDTA, and 90 - 95% deionized water. The cleaning temperature is 25°C - 40°C, the ultrasonic frequency for cleaning is 30 - 50 KHz, the ultrasonic power is 30 - 60 W, and the cleaning time is 2 min - 3 min.

[0021] S42. Immersion cleaning with deionized water. The cleaning temperature is 50°C - 80°C, the ultrasonic frequency for cleaning is 30 - 50 KHz, the ultrasonic power is 30 - 60 W, and the cleaning time is 2 min - 3 min.

[0022] As a further improved technical solution of the present invention, in step S5, the wavelength of the femtosecond laser is 515 nm or 1030 nm, the pulse is 200 fs - 500 fs, the repetition frequency is 100 KHz - 1 MHz, the single - pulse energy is 10 - 50 μJ, and the scanning speed is 0.2 - 0.5 m / s.

[0023] As a further improved technical solution of the present invention, in step S5, the processing depth of the femtosecond laser is 20 μm - 30 μm, and the processing width is less than 10 μm.

[0024] From the above technical solutions, it can be seen that the method for manufacturing a fine - line printing stencil of the present invention has at least the following advantages:

[0025] 1. The stencil manufactured by the method for manufacturing a fine - line printing stencil of the present invention has higher hardness compared with the mesh + PI composite stencil. There is no interference from the fiber structure, the opening edge is smooth, the edge of the printed grid line is not easily deformed, the grid line pattern is consistent before and after 200,000 prints, and at the same time, the widening of the grid line is smaller.

[0026] 2. The method for manufacturing a fine - line printing stencil of the present invention can control the pre - filling position of the paste. During the subsequent printing process, the paste can be scraped and filled into the grid line position by a squeegee. The paste is easily permeable, has good ink permeability, and the printed grid line is fully filled with ink and has a full pattern.

[0027] 3. The fine - line printing stencil manufactured by the method of the present invention has no horizontal wire diameter and lower line - type undulation compared with the screen cloth stencil made by the traditional mesh + PI film composite process.

[0028] 4. The method for manufacturing a fine - line printing stencil of the present invention can break through the limit of the traditional stencil line width. The minimum opening can reach 5 μm, and the grid line width after printing and sintering can reach less than 10 μm.

[0029] Therefore, through the present invention, the width of the gate line can be significantly reduced, thereby reducing the light shielding of the gate line, enhancing the short-circuit current, increasing the height of the gate line, and further significantly increasing the aspect ratio of the gate line. Moreover, the printing undulation of the gate line can be reduced, thereby enhancing the filling and improving the efficiency of the solar cell. Description of the Drawings

[0030] Figure 1 It is a schematic diagram of the laser scanning position during the first laser scanning modification.

[0031] Figure 2 It is a schematic diagram of the groove formed after the first laser scanning modification.

[0032] Figure 3 It is a schematic diagram of the laser scanning position during the second laser scanning modification.

[0033] Figure 4 It is a schematic diagram of the groove formed after the second laser scanning modification.

[0034] Figure 5 It is a micrograph of the screen-printed gate line fabricated by the method of Example 1.

[0035] Figure 6 It is a micrograph of the screen-printed gate line fabricated by the method of the comparative example. Detailed Description of the Embodiments

[0036] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] S1: Prepare a glass substrate: Select a glass substrate with a thickness of 60 μm.

[0039] S2: First laser scanning modification: Use a femtosecond laser with a wavelength of 515 nm, a pulse width of 200 fs, a repetition rate of 1000 KHz, a single-pulse energy of 20 μJ, and a scanning speed of 0.3 m / s to scan and modify the preset graphic area on the first side 11 of the glass substrate 10 (please refer to Figure 1 shown), where l1 represents the scanning path; control the laser modification depth to be 38.7 μm, and the remaining unmodified glass substrate thickness to be 21.7 μm.

[0040] S3: First cleaning

[0041] S31: Cleaning with cleaning solution: Use a cleaning solution with a formula of 1.5% hydrofluoric acid, 4% nitric acid, 0.3% polyoxyethylene octylphenol ether, 0.5% disodium EDTA, and 90.7% deionized water. Clean for 2 min under the conditions of a temperature of 25°C, an ultrasonic frequency of 40 KHz, and an ultrasonic power of 50 W to remove the modified glass at l1. A groove l1 as shown in Figure 2 is formed on the first side of the glass substrate.

[0042] S32: Immersion cleaning with deionized water: Immerse and clean the glass substrate in deionized water at a temperature of 50°C, an ultrasonic frequency of 40 KHz, and an ultrasonic power of 50 W for 2 min.

[0043] S4: Second laser scanning modification: Use femtosecond laser pulses to scan and modify the area corresponding to the preset pattern on the second side of the glass substrate, and modify the remaining glass after the modification in S2 (please refer to Figure 3 shown). The femtosecond laser parameters are: pulse of 200 fs, repetition frequency of 150 KHz, single pulse energy of 30 μJ, and scanning speed of 0.5 m / s.

[0044] S5: Second cleaning

[0045] S51: Cleaning with cleaning solution: Use the same cleaning solution and conditions as in S31, and clean for 2 min. A groove l2 as shown in Figure 4 is formed on the second side 12 of the glass substrate, and the groove l2 penetrates through the groove l1.

[0046] S52: Immersion cleaning with deionized water: Use the same conditions as in S32, and immerse and clean for 2 min.

[0047] Example 2

[0048] S1: Prepare a glass substrate: Prepare a glass substrate with a thickness of 80 μm.

[0049] S2: First laser scanning modification: Select a femtosecond laser with a wavelength of 1030 nm, a pulse of 400 fs, a repetition frequency of 800 KHz, a single pulse energy of 30 μJ, and a scanning speed of 0.3 m / s to scan and modify the preset pattern area on the first side of the glass substrate, so that the laser modification depth reaches 59.1 μm, and the thickness of the unmodified glass substrate is 21.9 μm.

[0050] S3: First cleaning

[0051] S31: Cleaning with cleaning solution: The cleaning solution formula remains unchanged. Clean for 2.5 min in an environment with a temperature of 30°C, an ultrasonic frequency of 40 KHz, and an ultrasonic power of 50 W.

[0052] S32: Immersion cleaning with deionized water: Immerse and clean in deionized water at a temperature of 60 °C, an ultrasonic frequency of 40 KHz, and an ultrasonic power of 50 W for 2.5 min.

[0053] S4: Second laser scanning modification: On the second side of the glass substrate, use femtosecond laser pulses with a wavelength of 1030 nm, a pulse width of 400 fs, a repetition frequency of 300 KHz, a single-pulse energy of 30 μJ, and a scanning speed of 0.5 m / s to scan and modify the corresponding area.

[0054] S5: Second cleaning

[0055] S51: Cleaning with cleaning solution: Under the same conditions as S31, clean for 2.5 min.

[0056] S52: Immersion cleaning with deionized water: Under the same conditions as S32, immerse and clean for 2.5 min.

[0057] Example 3

[0058] S1: Prepare a glass substrate: Take a glass substrate with a thickness of 70 μm.

[0059] S2: First laser scanning modification: Use a femtosecond laser with a wavelength of 515 nm, a pulse width of 200 fs, a repetition frequency of 500 KHz, a single-pulse energy of 30 μJ, and a scanning speed of 0.25 m / s to modify the preset graphic area on the first side of the glass substrate, so that the laser modification depth is 43.2 μm, and the remaining unmodified glass substrate thickness is 26.8 μm.

[0060] S3: First cleaning

[0061] S31: Cleaning with cleaning solution: Clean with the established formula cleaning solution at a temperature of 35 °C, an ultrasonic frequency of 40 KHz, and an ultrasonic power of 50 W for 3 min.

[0062] S32: Immersion cleaning with deionized water: Immerse and clean in deionized water at a temperature of 70 °C, an ultrasonic frequency of 40 KHz, and an ultrasonic power of 50 W for 3 min.

[0063] S4: Second laser scanning modification: On the second side of the glass substrate, use femtosecond laser pulses with a wavelength of 515 nm, a pulse width of 200 fs, a repetition frequency of 300 KHz, a single-pulse energy of 20 μJ, and a scanning speed of 0.4 m / s to modify the corresponding area.

[0064] S5: Second cleaning

[0065] S51: Cleaning with cleaning solution: Under the same conditions as S31, clean for 3 min.

[0066] S52: Immersion cleaning with deionized water: Under the same conditions as S32, immerse and clean for 3 min.

[0067] Example 4

[0068] S1: Prepare a glass substrate: Select a glass substrate with a thickness of 60 μm.

[0069] S2: First laser scanning modification: Use femtosecond laser with a wavelength of 1030 nm, a pulse of 400 fs, a repetition frequency of 200 KHz, a single pulse energy of 50 μJ, and a scanning speed of 0.2 m / s to modify the preset graphic area on the first side of the glass substrate, so that the laser modification depth is 34.3 μm, which is 25.7 μm smaller than the thickness of the glass substrate.

[0070] S3: First cleaning

[0071] S31: Cleaning with cleaning solution: Clean with the cleaning solution for 3 min under the conditions of a temperature of 40 °C, an ultrasonic frequency of 40 KHz, and an ultrasonic power of 50 W.

[0072] S32: Immersion cleaning with deionized water: Immerse and clean in deionized water at a temperature of 80 °C, an ultrasonic frequency of 40 KHz, and an ultrasonic power of 50 W for 3 min.

[0073] S4: Second laser scanning modification: On the second side of the glass substrate, use femtosecond laser pulses with a wavelength of 1030 nm, a pulse of 400 fs, a repetition frequency of 500 KHz, a single pulse energy of 20 μJ, and a scanning speed of 0.4 m / s to modify the corresponding area.

[0074] S5: Second cleaning

[0075] S51: Cleaning with cleaning solution: The conditions are the same as S31, and clean for 3 min.

[0076] S52: Immersion cleaning with deionized water: The conditions are the same as S32, and immerse and clean for 3 min.

[0077] Comparative Example 1

[0078] S1: Prepare a glass substrate: Select a glass substrate with a thickness of 60 μm.

[0079] S2: Laser scanning modification: Directly use femtosecond laser pulses to perform one-time scanning modification on the preset graphic area on the first side of the glass substrate. Use femtosecond laser with a wavelength of 1030 nm, a pulse of 400 fs, a repetition frequency of 800 KHz, a single pulse energy of 30 μJ, and a scanning speed of 0.3 m / s to process the entire glass substrate to a depth of 60 μm.

[0080] S31: Cleaning with cleaning solution: Use a cleaning solution with a formula of 1.5% hydrofluoric acid, 4% nitric acid, 0.3% polyoxyethylene octylphenol ether, 0.5% disodium EDTA, and 90.7% deionized water. Clean for 2.5 min under the conditions of a temperature of 30°C, an ultrasonic frequency of 40 KHz, and an ultrasonic power of 50 W to remove the modified glass in the laser irradiation area.

[0081] S32: Immersion cleaning with deionized water: Immerse and clean the glass substrate in deionized water at a temperature of 60°C, an ultrasonic frequency of 40 KHz, and an ultrasonic power of 50 W for 2.5 min.

[0082] Use the stencils made in Examples 1-4 and the comparative example for grid line printing, and measure the height and width of the printed grid lines. For the results, please refer to Table 2. Figure 5 and Figure 6 .

[0083] Table 1 Laser parameters of each example and comparative example

[0084]

[0085] Table 2 Laser processing dimension parameters of each example and comparative example

[0086]

[0087] Judging from the data in Table 2, in the second laser processing of Examples 1-4, the depth h2 is 21.7 - 26.8 μm, and the width w2 is 5.0 - 6.9 μm. Such dimensions form a relatively narrow groove with a certain depth. When printing grid lines, the narrow width limits the spreading range of the paste, which is conducive to forming fine grid lines; the appropriate depth can accommodate an appropriate amount of paste to ensure the thickness and conductivity of the grid lines and other properties. For example, the width of the second processing in Example 1 is only 5.0 μm, providing a narrow space for the formation of ultra-fine grid lines. In addition, in the examples, the width w1 is greater than the width w2. When printing, pressing the second side of the glass substrate against the battery cell makes it easy for the paste to penetrate, with good ink permeability. The printed grid lines are fully filled with ink and have a plump line type.

[0088] Comparing the width data of the first and second laser processing in the comparative examples, for example, in Example 1, the width w1 of the first processing is 10.1 μm, and the width w2 of the second processing is reduced to 5.0 μm, with a significant reduction in width. By processing in two sides, the second processing is a precise treatment of the remaining part of the first processing, which can effectively control the processing range and avoid the increase in width caused by over-processing, thereby obtaining a narrower groove for printing ultra-fine grid lines. While in the comparative example, only one-side processing is carried out, with a width of 15.1 μm, which is much larger than the width of the second processing in the examples and is not conducive to the formation of ultra-fine grid lines.

[0089] In the embodiment, the second laser processing depth h2 cooperates with the first one h1, enabling the overall processing depth to meet the requirements of the printed grid lines for the depth, and at the same time, not affecting the performance of the glass substrate due to excessive depth. For example, in Embodiment 2, the first processing depth is 59.1μm, and the second one is 21.9μm. The overall depth is appropriate, and the groove can stably carry the printing paste, ensuring the quality of the grid lines and facilitating the formation of ultra-fine and well-performing grid lines.

[0090] Through the above embodiments and comparative examples, it can be verified by comparison that the grooves formed by laser processing the glass substrate on both sides in this technical solution have obvious advantages in precise control of dimensions, that is, reducing the processing width and increasing the processing depth, creating good conditions for achieving the printing effect of ultra-fine grid lines.

[0091] The above embodiments are only used to illustrate the present invention and do not limit the technical solutions described in the present invention. The understanding of this specification should be based on those skilled in the art of the relevant technical field. Although this specification has described the present invention in detail with reference to the above embodiments, those of ordinary skill in the art should understand that those skilled in the relevant technical field can still modify the present invention or make equivalent replacements. All technical solutions and their improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for manufacturing a fine-line printing stencil, characterized in that: Including: S1: Prepare a glass substrate; S2: First laser modification: Use femtosecond laser pulses to scan and modify a preset graphic area on the first side of the glass substrate, and the depth of the laser modification is less than the thickness of the glass substrate; S3: Clean the glass substrate to remove the modified glass in the laser irradiation area of S2; S4: Second laser modification: Use femtosecond laser pulses to scan and modify the area corresponding to the preset graphic on the second side of the glass substrate, so as to modify the remaining glass after modification in S2 in the thickness direction of the glass substrate; S5: Clean the glass substrate to remove the modified glass in the laser irradiation area of S4.

2. The manufacturing method of the fine-line printed stencil according to claim 1, characterized in that: The thickness of the glass substrate is 50 - 80 μm.

3. The method for manufacturing a fine-line printed stencil according to claim 2, wherein: In step S2, the processing depth of the femtosecond laser is 40 μm - 60 μm.

4. The manufacturing method of the thinned printing stencil according to claim 1, wherein: In step S2, the wavelength of the femtosecond laser is 515 nm or 1030 nm, the pulse is 200 fs - 500 fs, the repetition frequency is 100 KHz - 1 MHz, the single pulse energy is 10 - 50 μJ, and the scanning speed is 0.2 - 0.5 m / s.

5. The method for manufacturing a fine-line printed stencil according to claim 1, characterized in that: The S3 step includes: S31. Clean with a cleaning solution, and the formula of the cleaning solution is 1 - 3% hydrofluoric acid, 3 - 5% nitric acid, 0.1 - 1% polyoxyethylene octylphenol ether, 0.1 - 1% disodium EDTA, 90 - 95% deionized water. The cleaning temperature is 25°C - 40°C, the ultrasonic frequency for cleaning is 30 - 50 KHz, the ultrasonic power is 30 - 60 W, and the cleaning time is 2 min - 3 min; S32. Soak and clean with deionized water, the cleaning temperature is 50°C - 80°C, the ultrasonic frequency for cleaning is 30 - 50 KHz, the ultrasonic power is 30 - 60 W, and the cleaning time is 2 min - 3 min.

6. The method for manufacturing a fine-line printed stencil according to claim 5, characterized in that: In the S31 step, the formula of the cleaning solution is 1.5% hydrofluoric acid, 4% nitric acid, 0.3% polyoxyethylene octylphenol ether, 0.5% disodium EDTA, 93.7% deionized water.

7. The manufacturing method of the thinned printing stencil according to claim 1, characterized in that: The S4 step includes: S41. Clean with a cleaning solution, and the formula of the cleaning solution is 1 - 3% hydrofluoric acid, 3 - 5% nitric acid, 0.1 - 1% polyoxyethylene octylphenol ether, 0.1 - 1% disodium EDTA, 90 - 95% deionized water. The cleaning temperature is 25°C - 40°C, the ultrasonic frequency for cleaning is 30 - 50 KHz, the ultrasonic power is 30 - 60 W, and the cleaning time is 2 min - 3 min; S42. Soak and clean with deionized water, the cleaning temperature is 50°C - 80°C, the ultrasonic frequency for cleaning is 30 - 50 KHz, the ultrasonic power is 30 - 60 W, and the cleaning time is 2 min - 3 min.

8. The method for manufacturing a fine-line printed stencil according to claim 1, wherein: In step S5, the wavelength of the femtosecond laser is 515 nm or 1030 nm, the pulse is 200 fs - 500 fs, the repetition frequency is 100 KHz - 1 MHz, the single pulse energy is 10 - 50 μJ, and the scanning speed is 0.2 - 0.5 m / s.

9. The manufacturing method of the thinned printing stencil according to claim 1, characterized in that: In step S5, the processing depth of the femtosecond laser is 20 μm - 30 μm, and the processing width is less than 10 μm.

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