Solar cell silk-screen printing plate and preparation method thereof

Abstract

The invention provides a preparation method of a solar cell silk-screen printing plate, which is characterized by comprising the following steps: S1, integral coating: coating a first layer of photo-sensitive resist on a steel wire mesh printing pattern area; s2, finding and determining the specific position of the edge of the steel wire mesh printing pattern; and S3, local thickening: taking the outside of the edge of the printing pattern of the steel wire mesh as a boundary, and coating a second layer of photo-sensitive adhesive in the steel wire mesh area outside the boundary. The precise local thickening solves the contradiction between edge abrasion, slurry leakage and service life reduction and overall thickening and cost increase, the service life of the screen printing plate is remarkably prolonged, the production efficiency is remarkably improved on the premise that the printing quality is guaranteed and the slurry cost is controlled, and economic benefits are remarkable.

Description

Technical Field

[0001] The present invention belongs to the field of solar cells, and in particular relates to a solar cell screen printing screen plate and a preparation method thereof. Background Art

[0002] In the manufacturing process of crystalline silicon solar cells, screen printing is a key step in forming cell electrodes (such as silver grid lines). The core component is the screen printing plate ("screen"). The screen is typically composed of a taut polyester mesh (1) and a steel mesh. The screen's pattern area (2) is coated with photoresist, which is then exposed and developed to form the specific printed pattern. During printing, the slurry is squeezed through the patterned openings on the screen by a squeegee and transferred to the silicon wafer surface.

[0003] In existing technology, to improve printing accuracy and image resolution, the photosensitive resin layer on the screen printing pattern area is typically designed to be relatively thin. However, in actual printing operations, the edges of silicon wafers are often sharp. During the high-speed, continuous printing process, the screen inevitably comes into contact and rubs against the edges of the silicon wafer. Over time, the thin thickness of the photosensitive resin layer at the edge of the printed pattern area, which is directly exposed to friction from the sharp edges of the silicon wafer, becomes a significant weakness. The photosensitive resin in this area is easily worn, abraded, or develops microcracks.

[0004] Once the photoresist layer is worn, it directly leads to serious slurry leakage: slurry can leak from the damaged area into areas not intended for printing, contaminating the silicon wafer, equipment, or causing slurry waste. Slurry leakage not only directly affects the quality and yield of the solar cells, but also directly causes screen failure, forcing production lines to stop for screen replacement or repair. This is currently one of the main factors limiting screen life (usually measured by the number of qualified silicon wafers that can be printed on a single screen). Frequent downtime for replacement also results in significant production capacity loss and increased production costs.

[0005] An intuitive solution to this problem is to increase the overall thickness of the photosensitive adhesive in the screen-printed graphic area to improve its overall wear resistance. However, this single thickening method brings new disadvantages: excessive thickness of the photosensitive adhesive layer in the printed graphic area will significantly increase the amount of ink flowing through the slurry (i.e., the volume of slurry passing through the screen opening increases). On the one hand, the increased ink flow may cause the printed electrode grid lines to become wider, increase in height, and even cause adhesion, affecting the electrical performance (such as series resistance and shading area) and appearance of the battery. On the other hand, more directly, it causes a significant increase in the unit consumption of slurry (the amount of slurry consumed per unit cell). Since slurry (especially silver paste) is an important component of the manufacturing cost of solar cells, this greatly increases production costs and is economically unacceptable.

[0006] Therefore, existing technologies face an irreconcilable conflict between improving screen wear life and maintaining print quality and controlling slurry costs. There is an urgent need for an innovative screen design and preparation method that can precisely and locally enhance the wear resistance of screens in areas prone to wear (particularly the periphery of the printed pattern, where they come into contact with sharp silicon wafer edges) while maintaining the original photoresist thickness in the core areas of the printed pattern. This approach effectively extends screen life without increasing ink overprinting or slurry consumption, reducing downtime and production losses caused by slurry leaks. Summary of the Invention

[0007] In order to resolve the irreconcilable contradiction between the existing technology in improving the wear resistance of the screen and maintaining printing quality and controlling the slurry cost, the purpose of the present invention is to provide a solar cell screen printing screen and a preparation method, so as to effectively extend the service life of the screen without increasing the amount of ink overflow and the unit consumption of slurry, and reduce the number of shutdowns and production capacity losses caused by slurry leakage.

[0008] The present invention achieves the above technical effects through the following technical solutions:

[0009] The present invention provides a method for preparing a solar cell screen printing screen, comprising the following steps:

[0010] S1. Overall coating: Apply the first layer of photosensitive adhesive to the screen printing graphic area;

[0011] S2. Find and determine the specific position of the edge of the screen printing pattern;

[0012] S3. Local thickening: Use the edge of the screen-printed pattern as the boundary, and apply a second layer of photosensitive adhesive to the screen area outside this boundary.

[0013] Preferably, in the step S3, the outside of the edge of the screen-printed pattern refers to 0.3 to 0.7 mm away from the edge of the screen-printed pattern.

[0014] Preferably, in the step S1, the thickness of the first layer of photosensitive adhesive is 8-15 μm.

[0015] Preferably, in step S3, the thickness of the second layer of photosensitive adhesive is 5-15 μm.

[0016] Preferably, in the step S3, a transition zone is formed between the boundary and the edge of the screen-printed pattern, and the thickness of the photosensitive resin on the transition zone is 8-15 μm.

[0017] The present invention provides a solar cell screen printing screen plate, which is prepared by adopting the above method.

[0018] Preferably, the solar cell screen printing screen of the present invention includes a steel mesh coated with photosensitive adhesive, the steel mesh includes a printing graphic area and a reinforcement area surrounding the printing graphic area, and the thickness of the photosensitive adhesive on the reinforcement area is greater than the thickness of the photosensitive adhesive on the printing graphic area.

[0019] Preferably, a transition zone is provided between the printed graphic area and the reinforcement area, and the distance between the boundary of the transition zone and the edge of the printed graphic area is 0.3-0.7 mm.

[0020] Preferably, the thickness of the photosensitive adhesive on the transition area is consistent with the thickness of the photosensitive adhesive on the printing pattern area.

[0021] Preferably, the thickness of the photosensitive adhesive on the printed graphic area is 8 to 15 μm; the thickness of the photosensitive adhesive on the transition area is 5 to 15 μm higher than that on the printed graphic area.

[0022] The solar cell screen printing screen and preparation method provided by the present invention have the following significant beneficial effects compared with the existing technology:

[0023] 1. Significantly Improved Lifespan: By locally thickening the photosensitive resin by 5-15μm in an area 0.3-0.7mm outside the printed pattern edge, this technology enhances wear resistance and effectively protects against sharp wafer edges. The lifespan of the screen has been increased from approximately 102,458 sheets / plate to 156,388 sheets / plate, a 52% improvement.

[0024] 2. Sharp reduction in shutdowns due to slurry leakage: The reinforced area effectively prevents the edge photosensitive resin from being worn out and leaking. The number of shutdowns due to slurry leakage has dropped from 10 times a day to 2 times (a decrease of 80%), and the production capacity loss has been reduced by 3.3%.

[0025] 3. Strict cost control and quality assurance: The thickness of the photosensitive resin in the core printing graphic area remains unchanged at 8-15μm to avoid the increase in ink overload and slurry consumption caused by overall thickening, ensuring the stable quality of printed electrodes without increasing slurry costs.

[0026] 4. Reliable structure and easy implementation: The transition zone is set to ensure a smooth transition in thickness and a reliable structure; the preparation process (overall coating + local thickening) is easy to implement, with low transformation cost and significant benefits.

[0027] The precise local thickening of the present invention solves the contradiction between "edge wear and leakage of slurry reducing life" and "overall thickening increasing costs". Under the premise of ensuring printing quality and controlling slurry costs, it significantly improves the life of the screen and production efficiency, with significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the screen structure of the prior art.

[0029] Figure 2 It is a schematic diagram of the screen structure of the present invention. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the present invention and are not intended to limit 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.

[0031] In order to make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved more clear, the technical solutions of the embodiments of the present invention are described in further detail below.

[0032] In a first aspect, the present invention provides a method for preparing a solar cell screen printing screen, comprising the following steps:

[0033] S1, overall coating: the first layer of photosensitive adhesive is applied to the screen printing graphic area 2;

[0034] S2. Find and determine the specific position of the edge of the screen printing pattern;

[0035] S3. Local thickening: Use the edge of the screen-printed pattern as the boundary, and apply a second layer of photosensitive adhesive to the screen area outside this boundary.

[0036] In some specific embodiments, in the step S3, the outside of the edge of the screen-printed pattern refers to 0.3-0.7 mm away from the edge of the screen-printed pattern.

[0037] In some specific embodiments, in the step S1, the thickness of the first layer of photosensitive adhesive is 8-15 um.

[0038] In some specific embodiments, in step S3, the thickness of the second layer of photosensitive adhesive is 5-15 um.

[0039] In some specific embodiments, in the step S3, a transition zone is formed between the boundary and the edge of the screen-printed pattern, and the thickness of the photosensitive resin in the transition zone is 8-15 um.

[0040] In a second aspect, the present invention provides a solar cell screen printing screen plate, which is prepared by the aforementioned method.

[0041] The solar cell screen printing screen provided by the present invention includes a steel mesh coated with photosensitive adhesive, the steel mesh includes a printing graphic area 2 and a reinforcement area 3 surrounding the printing graphic area 2, and the thickness of the photosensitive adhesive on the reinforcement area 3 is greater than the thickness of the photosensitive adhesive on the printing graphic area 2.

[0042] In some specific embodiments, a transition zone is provided between the printed graphic area 2 and the reinforcement area 3 , and the distance between the boundary of the transition zone and the edge of the printed graphic area 2 is 0.3-0.7 mm.

[0043] In some specific embodiments, the thickness of the photosensitive adhesive on the transition area is consistent with the thickness of the photosensitive adhesive on the printed pattern area 2 .

[0044] In some specific embodiments, the thickness of the photosensitive adhesive on the printed graphic area 2 is 8-15 um; the thickness of the photosensitive adhesive on the transition area is 5-15 um higher than that on the printed graphic area 2.

[0045] The following is an example of a specific embodiment: first, a 400-mesh stainless steel wire mesh substrate is prepared. After cleaning and drying, EP320 photosensitive resin photosensitive adhesive is evenly coated on the entire surface of the wire mesh. The thickness of the first layer of adhesive is controlled to 10μm (within the range of 8-15μm) by a precision scraper, forming a basic adhesive layer for the printed pattern area 2; then, a high-precision CCD vision system is used to identify and locate the edge of the printed pattern, and the edge is extended by 0.5mm (within the range of 0.3-0.7mm) as the boundary line. A second coating is performed on the area outside this boundary line (i.e., the reinforced area 3), and the same type of photosensitive adhesive is thickened by 8μm (within the range of 5-15μm), so that the total thickness of the reinforced area 3 reaches 18μm. At the same time, the 0.5mm transition zone from the boundary line to the edge of the pattern maintains the original thickness of 10μm. Finally, the printed pattern is formed by exposure and development, and the finished screen is cured. To validate the effectiveness, the screen was tested on a 182mm×182mm silicon wafer production line. The results showed that the average screen lifespan increased from 102,458 wafers (compared to a traditional uniform-thickness screen (10μm)) to 156,388 wafers (a 52.6% increase). The average daily downtime due to slurry leaks decreased from 10 to 2 (an 80% decrease). The core printing pattern area 2 glue thickness remained unchanged at 10μm, with no significant change in slurry consumption. The gridline width accuracy remained stable within ±5μm. During implementation, the pattern edge recognition error was maintained at ≤0.05mm, and the secondary coating thickness fluctuation was ≤±1μm. The transition zone design effectively avoided stress cracking caused by sudden thickness changes. This solution only increased the amount of photosensitive adhesive by approximately 5%, allowing for upgrades to existing coating equipment. The overall cost per screen was reduced by 37%, and it has been successfully implemented in PERC / TOPCon cell mass production.

[0046] 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 method for preparing a solar cell screen printing screen, characterized in that: The following steps are involved: S1. Overall coating: Apply the first layer of photosensitive adhesive to the screen printing graphic area; S2. Find and determine the specific position of the edge of the screen printing pattern; S3. Local thickening: Use the edge of the screen-printed pattern as the boundary, and apply a second layer of photosensitive adhesive to the screen area outside this boundary.

2. The method for preparing a solar cell screen printing screen according to claim 1, wherein: In the step S3, the outside of the edge of the screen-printed pattern refers to 0.3 to 0.7 mm away from the edge of the screen-printed pattern.

3. The method for preparing a solar cell screen printing screen according to claim 1, wherein: In the step S1, the thickness of the first layer of photosensitive adhesive is 8-15 μm.

4. The method for preparing a solar cell screen printing screen according to claim 1, wherein: In step S3, the thickness of the second layer of photosensitive adhesive is 5-15 μm.

5. The method for preparing a solar cell screen printing screen according to claim 1, wherein: In the step S3, a transition zone is formed between the boundary and the edge of the screen-printed pattern, and the thickness of the photosensitive resin on the transition zone is 8-15 μm.

6. A solar cell screen printing screen, characterized in that: The solar cell screen printing screen is prepared by the method according to claims 1 to 5.

7. The solar cell screen printing screen according to claim 6, characterized in that: The invention comprises a steel mesh coated with photosensitive adhesive. The steel mesh comprises a printing pattern area and a reinforcement area surrounding the printing pattern area. The thickness of the photosensitive adhesive on the reinforcement area is greater than that on the printing pattern area.

8. The solar cell screen printing screen according to claim 6, characterized in that: A transition zone is provided between the printed graphic zone and the reinforcement zone, and the distance between the boundary of the transition zone and the edge of the printed graphic zone is 0.3-0.7 mm.

9. The solar cell screen printing screen according to claim 6, characterized in that: The thickness of the photosensitive adhesive on the transition area is consistent with the thickness of the photosensitive adhesive on the printing pattern area.

10. The solar cell screen printing screen according to claim 6, characterized in that: The thickness of the photosensitive adhesive on the printed graphic area is 8 to 15 μm; the thickness of the photosensitive adhesive on the transition area is 5 to 15 μm higher than that on the printed graphic area.

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