Solar cell screen electroforming process for improving thickness uniformity

Abstract

The invention belongs to the technical field of solar cell screen electroplating, and particularly relates to a solar cell screen electroforming process for improving thickness uniformity, which comprises the following steps: dividing an electroforming area into a plurality of sub-areas, namely a central area, a transition area and an edge area; an independent anode group is configured in each sub-region, the anode current density in the central region is relatively high, and the anode current density in the edge region is gradually reduced; a direct-current pulse composite power supply is adopted, direct current is mainly superimposed on low-frequency pulses in a central area, and high-frequency pulses are mainly superimposed on direct-current compensation in an edge area; by adjusting the anode density and the anode size, finely regulating and controlling the electric field distribution and reducing the influence of the fringe effect, the method has the effects of breaking through the limitation of a single technical path and providing an innovative scheme for manufacturing the high-efficiency solar cell screen printing plate through composite power supply regulation and control and partition optimization.

Description

Technical Field

[0001] This invention relates to the technical field of electroforming of battery screens, specifically an electroforming process for solar cell screens that improves thickness uniformity. Background Technology

[0002] The efficient fabrication of solar cells is crucial for promoting the development of clean energy. In the production process of solar cells, screen electroforming is a commonly used metal electrodeposition technique to form a uniform metal layer on the surface of the solar cell, thereby enhancing its electrical performance. However, current screen electroforming processes often struggle to ensure the uniformity of the coating thickness on the cell surface, leading to unstable overall performance and affecting its conversion efficiency and lifespan. Therefore, developing a screen electroforming process that improves thickness uniformity is of great significance for enhancing the quality and performance of solar cells.

[0003] In existing screen electroforming processes, a constant current density method is typically used for metal deposition. While this method is simple and easy to implement, it does not always yield a uniform coating thickness. Especially in large-area electrodeposition operations, uneven current distribution can lead to significant thickness variations in different areas of the coating, further impacting the overall performance of the cell. Furthermore, traditional screen electroforming processes struggle to achieve uniform coverage on complex cell surfaces. Therefore, improving the screen electroforming process to enhance coating thickness uniformity is one of the most pressing issues to be addressed in the field of solar cell manufacturing.

[0004] To address the aforementioned technical challenges, some existing technologies employ methods such as gradually adjusting the current or optimizing the current distribution through improvements in screen design. However, these methods are often complex and costly, limiting their widespread application to mass production and complex cell surfaces. Therefore, a simple, economical screen electroforming process that effectively improves thickness uniformity is of high practical value for enhancing the quality and performance of solar cells.

[0005] To address the aforementioned technical shortcomings, a solution for improving the thickness uniformity of solar cell screen electroforming process is proposed. Summary of the Invention

[0006] To address the above problems, the present invention provides the following technical solution: An electroforming process for solar cell screens to improve thickness uniformity includes: The electroforming area is divided into multiple sub-regions, namely the central area, the transition area, and the edge area; Each sub-region is configured with an independent anode group, with a higher anode current density in the central region and a progressively lower anode current density in the edge regions. A DC pulse composite power supply is adopted, with DC as the main component superimposed with low-frequency pulses in the central area and high-frequency pulses superimposed with DC compensation in the edge area. By adjusting the anode density and anode size, the electric field distribution can be precisely controlled, reducing the impact of edge effects.

[0007] Furthermore, the anode array is a 6×6 array, with a 2×2 anode group in the central area, a 1-ring anode group in the transition area, and a 2-ring anode group in the edge area; the anode spacing in the central area is 20mm, in the transition area it is 25mm, and in the edge area it is 30mm.

[0008] Furthermore, the power system includes 10 independent pulse-DC composite power modules, with the central power module operating in DC mode, the transition power module operating at 10kHz, and the edge power module operating at 15kHz.

[0009] Furthermore, the electrolyte adopts a nickel sulfamate system, comprising the following components and their concentrations: nickel sulfamate: 380 g / L; boric acid: 35 g / L; sodium saccharin: 2.5 g / L; sodium dodecyl sulfate: 0.08 g / L; sodium tungstate: 1.2 g / L.

[0010] Furthermore, the electrolyte circulation system has a flow rate of 1.8 m / s and a Reynolds number of 6200, ensuring that the electrolyte is in a turbulent state.

[0011] Furthermore, the electroforming deposition parameter settings include the following: The current density of the power supply module in the central area is 3.2 A / dm². 2 DC mode; The current density of the power module in the transition zone is 3.0 A / dm². 2 The pulse frequency is 10kHz, and the duty cycle is 45%. The current density of the power module in the edge region is 2.5A / dm². 2 The pulse frequency is 15kHz and the duty cycle is 50%.

[0012] Furthermore, the substrate pretreatment step includes the following: Laser mask engraving: Fine grid patterns are engraved on the surface of a PI substrate, with a line width of 14±1μm; Ultrasonic cleaning: Use a mixture of isopropanol and deionized water at 50°C for 10 minutes. Plasma activation: O2 / Ar mixed gas is used at a pressure of 50 Pa and a power of 300 W for 5 minutes.

[0013] Furthermore, the temperature control includes a central area temperature of 55.0°C and an edge area temperature of 53.5°C, ensuring temperature uniformity through zoned temperature control.

[0014] Furthermore, the quality inspection uses a 9-point measurement method, and the thickness uniformity CV value is 2.57%.

[0015] Furthermore, the process improves the thickness uniformity of the solar cell screen electroforming and controls the thickness uniformity with a CV value ≤ 3%.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention discloses an electroforming process for solar cell screens that improves thickness uniformity. The electroforming area is divided into multiple sub-regions: a central region, a transition region, and an edge region. Each sub-region is equipped with an independent anode group. The anode current density is higher in the central region and gradually decreases in the edge region. A DC pulse composite power supply is used, with the central region primarily using DC pulses superimposed with low-frequency pulses, and the edge region primarily using high-frequency pulses superimposed with DC compensation. By adjusting the anode density and anode size, the electric field distribution is precisely controlled, reducing the impact of edge effects. This innovative solution, achieved through composite power supply control and zonal optimization, overcomes the limitations of a single technical path and provides a revolutionary solution for the manufacturing of high-efficiency solar cell screens. Attached Figure Description

[0017] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings; Figure 1 This is an overall schematic diagram of an electroforming process for solar cell screens to improve thickness uniformity according to the present invention; Figure 2 This is a diagram showing the distribution of electroforming regions in an electroforming process for solar cell screens to improve thickness uniformity according to the present invention. Figure 3 This is a segmented layout diagram of the electroforming area in the electroforming process of a solar cell screen to improve thickness uniformity, according to the present invention. Figure 4 This is a diagram showing the corresponding anode positions of the power module in a solar cell screen electroforming process for improving thickness uniformity, as described in this invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] like Figures 1-3 As shown, this application provides a solar cell screen electroforming process for improving thickness uniformity, comprising: S1: Divide the electroforming area into multiple sub-regions, namely the central area, the transition area, and the edge area; S2: Each sub-region is configured with an independent anode group, with a higher anode current density in the central region and a gradually decreasing anode current density in the edge region; S3: A DC pulse composite power supply is used, with DC as the main component and low-frequency pulse superimposed in the central area, and high-frequency pulse superimposed with DC compensation in the edge area. S4: By adjusting the anode density and anode size, the electric field distribution can be finely controlled to reduce the impact of edge effects.

[0020] Specifically, the anode array is a 6×6 array, with a 2×2 anode group in the central area, a 1-ring anode group in the transition area, and a 2-ring anode group in the edge area; the anode spacing in the central area is 20mm, in the transition area it is 25mm, and in the edge area it is 30mm.

[0021] Specifically, the power system includes 10 independent pulse-DC composite power modules, with the central power module operating in DC mode, the transition power module operating at 10kHz, and the edge power module operating at 15kHz.

[0022] Specifically, the electrolyte adopts a nickel sulfamate system, including the following components and their concentrations: nickel sulfamate: 380 g / L; boric acid: 35 g / L; sodium saccharin: 2.5 g / L; sodium dodecyl sulfate: 0.08 g / L; sodium tungstate: 1.2 g / L.

[0023] Specifically, the electrolyte circulation system has a flow rate of 1.8 m / s and a Reynolds number of 6200, ensuring that the electrolyte is in a turbulent state.

[0024] Specifically, the electroforming deposition parameter settings include the following: The current density of the power supply module in the central area is 3.2 A / dm². 2 DC mode; The current density of the power module in the transition zone is 3.0 A / dm². 2 The pulse frequency is 10kHz, and the duty cycle is 45%. The current density of the power module in the edge region is 2.5A / dm². 2 The pulse frequency is 15kHz and the duty cycle is 50%.

[0025] Specifically, the substrate pretreatment step includes the following: Laser mask engraving: Fine grid patterns are engraved on the surface of a PI substrate, with a line width of 14±1μm; Ultrasonic cleaning: Use a mixture of isopropanol and deionized water at 50°C for 10 minutes. Plasma activation: O2 / Ar mixed gas is used at a pressure of 50 Pa and a power of 300 W for 5 minutes.

[0026] Specifically, the temperature control includes a central area temperature of 55.0℃ and an edge area temperature of 53.5℃, ensuring temperature uniformity through zoned temperature control.

[0027] Specifically, the quality inspection uses a 9-point measurement method, and the thickness uniformity CV value is 2.57%.

[0028] Specifically, the process improves the thickness uniformity of the electroforming of solar cell screens and controls the thickness uniformity with a CV value ≤ 3%.

[0029] In one embodiment, the present invention adopts the following technical solution to achieve the above objective: A combination of pulse and DC power supplies is used, employing a multi-anode array arrangement. The electroforming area is divided into multiple sub-regions: a central region, a transition region, and an edge region (e.g., ...). Figure 2 Each region is equipped with an independent anode group, with a high anode current density in the central region and a gradual decrease in the edge region, thereby reducing the impact of the edge effect. The anode density and size in the central, transition, and edge regions can be adjusted to suit different solar cell patterns, allowing for fine-tuning of the electric field distribution and improving thickness uniformity. Regarding the power supply, the central region primarily uses DC, with low-frequency pulses superimposed to refine the grains. The edge region is dominated by high-frequency pulses, with DC compensation suppressing dendrite formation.

[0030] Equipment configuration list and functions:

[0031] The key equipment and methods in this invention are detailed below: A. Anode Array: 6x6 nickel anodes, segmented layout, 2x2 in the central area, one ring around the transition area, and two rings around the outermost edge area. The anode gap in the central area is 20mm, in the transition area it is 25mm, and in the edge area it is 30mm (e.g., ...). Figure 3 ); B. Power system: 10 independent pulse-DC composite power modules (15 kHz in the edge region, 10 kHz in the transition region, and DC mode in the center region).

[0032] Electroforming process flow: Step 1: Substrate Pretreatment Laser mask engraving: Parameters: Laser power 20W, scanning speed 500mm / s, line width 25±1 μm; Function: To etch the fine grid pattern required for solar cells onto the surface of a PI substrate.

[0033] Ultrasonic cleaning: A. Solution: Isopropanol:Deionized water = 1:3 (volume ratio), temperature 50℃; B. Time: 10 minutes, to remove organic matter and laser residue particles from the PI surface.

[0034] Plasma activation: A. Gas: O2 (80%) + Ar (20%), pressure 50Pa, power 300W, time 5 minutes; B. Effect: Surface energy is increased to 72 mN / m, and coating adhesion reaches level 5B.

[0035] Electrolyte preparation and maintenance: Electrolyte formulation (nickel sulfamate system):

[0036] Electrolyte maintenance: A. Daily supplementation with nickel salts (consumption ≈ 12 g / A·h); B. The pH value is checked every 8 hours, and the ammonia water is automatically adjusted (flow rate 0.5 L / h).

[0037] Electroforming deposition parameter settings: Power supply parameters:

[0038] Dynamic control of the electroforming process: Start electrolyte circulation: The flow velocity was 1.8 m / s, and the Reynolds number Re = 6200 (turbulent state) to ensure uniform mass transfer. Temperature control: central area: 55.0℃, edge area: 53.5℃ (to compensate for differences in current density).

[0039] Quality Inspection: Thickness uniformity: 9-point measurement method CV value = 2.57% (24.93 ± 0.64 μm).

[0040] The results obtained from the above embodiments, through optimization of anode layout and current distribution, inherit the advantages of pulse power supply in suppressing polarization while retaining the high-efficiency deposition characteristics of DC power supply, balancing the electric field distribution, reducing edge effects and local current density differences, thereby improving the uniformity of electroformed coatings. In actual long-term production and use, the thickness uniformity requirements (CV value ≤ 3%) of solar cell screen electroforming can be consistently met.

[0041] In one embodiment, infrared reprocessing and electropolishing techniques are used to reduce the roughness (Ra value) of the aperture walls in the electroformed stencil, thus solving the problems of slurry residue and uneven slurry application. The effectiveness of the two techniques in improving aperture wall roughness is verified. The influence of process parameters on the processing results is analyzed.

[0042] Experimental equipment and materials: Infrared processing equipment: Line-scanning infrared light source (wavelength 1.5-3μm), equipped with a precision XY-axis moving platform. Electropolishing equipment: Equipped with a high-speed jetting system and an online pH monitoring module. Testing equipment: SEM (Scanning Electron Microscope), roughness tester. Materials: Metal substrate, photoresist, nickel electroforming solution, electrolyte (sulfuric acid, phosphoric acid, citric acid, etc.).

[0043] Experimental Design: Experimental Groups: Group 1: Infrared reprocessing technology (10 groups).

[0044] Group 2: Electropolishing technology (10 groups).

[0045] Experimental parameters: Infrared processing: temperature (110-150℃), heating time (1-10s).

[0046] Electropolishing: Current density (15 A / dm) 2 Polishing time (120s), electrolyte pH (2.5±0.2).

[0047] Test metrics: Hole wall roughness (Ra value).

[0048] Residual development (microscopic burrs).

[0049] SEM image of the sidewall of an electroformed product.

[0050] The data is as follows: Group 1: Infrared reprocessing technology:

[0051] After infrared treatment, the roughness of the pore walls was significantly reduced (Ra value decreased from 0.10-0.20 μm to 0.02-0.06 μm). The improvement rate of residual development was between 70% and 80%, indicating that infrared heating effectively eliminated microburrs. Temperature and heating time had a significant impact on the treatment effect; the optimal process parameters were a temperature of 120-130℃ and a heating time of 2-3 seconds.

[0052] Group 2: Electropolishing Techniques

[0053] Electropolishing significantly improved the pore wall roughness (Ra value decreased from 0.15-0.25 μm to 0.04-0.08 μm). The slurry flowability improved by 70%-75%, indicating that electropolishing effectively enhanced the uniformity of slurry filling. Polishing time had a significant impact on the treatment effect; the optimal process parameter was a polishing time of 120 s.

[0054] Comparison of the two technologies: Infrared reprocessing technology is suitable for smoothing the hole walls of photolithography master molds, significantly reducing developer residue (improvement rate 70%-80%). Electropolishing technology is suitable for smoothing the hole walls of electroforming stencils, significantly improving slurry flowability (improvement rate 70%-75%). Using both technologies in combination can achieve a hole wall roughness Ra < 0.05 μm, meeting the requirements of high-precision electroforming stencils.

[0055] Process parameter optimization: Infrared treatment: Optimal temperature 120-130℃, heating time 2-3s.

[0056] Electropolishing: Optimal polishing time 120s, current density 15A / dm² 2 .

[0057] Practical application value: Both technologies can effectively reduce pore wall roughness and solve the problems of slurry residue and uneven slurry distribution. They are suitable for the preparation of high-precision electroforming stencils for lithium-ion battery separators, filter materials, etc.

[0058] This invention discloses an electroforming process for solar cell screens that improves thickness uniformity. The electroforming area is divided into multiple sub-regions: a central region, a transition region, and an edge region. Each sub-region is equipped with an independent anode group. The anode current density is higher in the central region and gradually decreases in the edge region. A DC pulse composite power supply is used, with the central region primarily using DC pulses superimposed with low-frequency pulses, and the edge region primarily using high-frequency pulses superimposed with DC compensation. By adjusting the anode density and anode size, the electric field distribution is precisely controlled, reducing the impact of edge effects. This innovative solution, achieved through composite power supply control and zonal optimization, overcomes the limitations of a single technical path and provides a revolutionary solution for the manufacturing of high-efficiency solar cell screens.

[0059] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, apparatus, article, or method that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, apparatus, article, or method. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, apparatus, article, or method that includes that element.

[0060] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to any specific implementation. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A solar cell stenciling electroforming process for improving thickness uniformity, characterized in that, The application relates to a solar cell screen printing plate electroforming method. The electroforming area is divided into multiple subareas, namely a center area, a transition area and an edge area; An independent anode group is arranged in each subarea, the anode current density of the center area is higher, and the anode current density of the edge area gradually decreases; A direct current pulse composite power supply is adopted, direct current is mainly used in the center area and is superimposed with low-frequency pulse, and high-frequency pulse is mainly used in the edge area and is superimposed with direct current compensation; The influence of the edge effect is reduced by adjusting the anode density and the anode size to finely control the electric field distribution.

2. The solar cell stenciling electroforming process with improved thickness uniformity according to claim 1, wherein, The anode array is a 6*6 array, the center area is 2*2 anode groups, the transition area is 1 anode group, and the edge area is 2 anode groups; the anode spacing of the center area is 20 mm, the anode spacing of the transition area is 25 mm, and the anode spacing of the edge area is 30 mm.

3. The solar cell stenciling electroforming process with improved thickness uniformity according to claim 1, wherein, The power supply system comprises 10 independent pulse-direct current composite power supply modules, the power supply module of the center area is in direct current mode, the power supply module of the transition area has a frequency of 10 kHz, and the power supply module of the edge area has a frequency of 15 kHz.

4. The solar cell stenciling electroforming process with improved thickness uniformity according to claim 1, wherein, The electrolyte adopts a nickel sulfamate system and comprises the following components and concentrations: nickel sulfamate: 380 g / L; boric acid: 35 g / L; sodium saccharin: 2.5 g / L; sodium dodecyl sulfate: 0.08 g / L; and sodium tungstate: 1.2 g / L. The flow velocity of the electrolyte circulating system is 1.8 m / s, and the Reynolds number is 6200, so that the electrolyte is ensured to be in a turbulent flow state.

5. The solar cell stenciling electroforming process with improved thickness uniformity according to claim 1, wherein, The electroforming deposition parameter setting comprises the following contents:

6. The solar cell stenciling electroforming process with improved thickness uniformity according to claim 5, wherein, The substrate pretreatment step comprises the following contents: The current density of the central zone power module is 3.2 A / dm 2 DC mode; The current density of the transition zone power module is 3.0 A / dm 2 The pulse frequency is 10 kHz, and the duty cycle is 45%. The edge region power module current density is 2.5 A / dm 2 with a pulse frequency of 15 kHz and a duty cycle of 50%.

7. The solar cell stenciling electroforming process with improved thickness uniformity according to claim 5, wherein, Laser mask engraving: a fine grid line pattern is engraved on the surface of the PI substrate, and the line width is 14+ / -1 mu m; Ultrasonic cleaning: an isopropyl alcohol and deionized water mixed solution is used, the temperature is 50 DEG C, and the cleaning time is 10 minutes; Plasma activation: O2 / Ar mixed gas is used, the pressure is 50 Pa, the power is 300 W, and the activation time is 5 minutes. The temperature control comprises the following contents: the temperature of the center area is 55.0 DEG C, the temperature of the edge area is 53.5 DEG C, and the temperature uniformity is ensured by partition temperature control.

8. The solar cell stenciling electroforming process with improved thickness uniformity according to claim 7, wherein, The quality detection adopts a 9-point measurement method, and the thickness uniformity CV value is 2.57%.

9. The solar cell stenciling electroforming process of claim 7, wherein, The process improves the thickness uniformity of solar cell screen printing plate electroforming and controls the thickness uniformity CV value to be less than or equal to 3%.

10. The solar cell stenciling electroforming process of claim 7, wherein, ​

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