Method for manufacturing a grid line and photovoltaic cell

Abstract

The present application relates to the technical field of process manufacturing, and discloses a grid line preparation method and a photovoltaic cell, the preparation method comprising: depositing a seed layer on a substrate; forming an insulating layer on the seed layer; forming an initial groove on the insulating layer; printing a mask line in the initial groove to obtain a target groove with a preset width; performing electroplating in the target groove by electroplating technology to form a conductive layer; and sequentially removing the insulating layer, the mask line, and the seed layer outside the conductive layer to form a grid line. The grid line preparation method provided by the present application is not constrained by the focusing size of laser optics, can flexibly adjust the width of the grid line according to actual needs, accurately control the width of the grid line, and realize fine processing. In the preparation process, the situation of underplating or overplating caused by poor stability of inkjet technology is greatly reduced, thereby reducing the risk of affecting the efficiency of the cell.

Description

Technical Field

[0001] This invention relates to the field of process manufacturing technology, specifically to a method for preparing grid lines and a photovoltaic cell. Background Technology

[0002] In photovoltaic (PV) cells, grid lines are a crucial structure. These are conductive lines formed on the cell surface, collecting electrons generated after photoelectric conversion and guiding them to the cell's output. In PV cell manufacturing, copper electroplating is a key electroplating technique, and patterning is a core component of this process. The exposure machine, as the core equipment for patterning, primarily utilizes photomask lithography or laser direct writing technology.

[0003] Photomask lithography primarily uses a mask to project a pattern onto a substrate surface, followed by exposure using an exposure machine to form the desired pattern on the substrate surface. Then, processes such as development and curing are performed to ultimately form a pre-plated patterned mask. However, exposure equipment and photoresist are expensive, and for heterojunction solar cells, the 15-20μm linewidth is difficult to develop. Insufficient development can easily lead to residual adhesive and oil at the bottom of the grid lines, affecting the adhesion of electroplated copper and even causing plating resistance.

[0004] Laser direct writing technology involves directly ablating the substrate surface with a laser to form a pre-plated patterned mask. However, this technology is limited by the optical focusing size of the laser equipment. For example, the minimum optical focusing size of commonly used CO2 laser equipment is only 35μm. Therefore, the minimum line width formed by a single laser ablation will be greater than 35μm, making it impossible to form more refined grid structures. Summary of the Invention

[0005] In view of this, the present invention provides a method for fabricating grid lines and a photovoltaic cell to solve the technical problem of low grid line fineness in the prior art.

[0006] In a first aspect, the present invention provides a method for fabricating a gate line, the method comprising:

[0007] Deposit a seed layer on the substrate;

[0008] An insulating layer is formed on the seed layer;

[0009] An initial groove is formed on the insulating layer, the depth of which is equal to the thickness of the insulating layer;

[0010] A mask line is printed within the initial groove to obtain a target groove of a preset width. The line width of the mask line is determined by the droplet diameter of the inkjet printer.

[0011] Electroplating technology is used to electroplat the target groove to form a conductive layer;

[0012] The insulating layer, mask lines, and seed layer outside the conductive layer are removed sequentially to form the gate lines.

[0013] The grid line fabrication method provided in this embodiment is not constrained by the laser optical focusing size. The width of the grid line can be flexibly adjusted according to actual needs, allowing for precise control and achieving high precision. Furthermore, during the fabrication process, only one mask line needs to be printed within the target groove. Compared to directly printing a mask layer on the substrate surface, the printing area is smaller, accounting for only 2%-5% of the total substrate area. This significantly improves the efficiency and process stability of inkjet printing, greatly reducing the risk of under-plating or over-plating due to the poor stability of inkjet technology, thereby lowering the risk of affecting battery efficiency.

[0014] In one optional embodiment, forming an initial groove on the insulating layer using laser ablation technology includes:

[0015] Determine the focusing size of the laser equipment; the focusing size is used to determine the size of the initial groove.

[0016] In this embodiment, the minimum focusing size of the laser equipment is determined first, and the initial groove is ablated based on the minimum focusing size, which can further reduce the use of subsequent printing materials and reduce the manufacturing cost.

[0017] In one alternative embodiment, an electroplating technique is used to electroplat the target groove to form a conductive layer, including:

[0018] Using copper electroplating technology, a copper electroplating layer is first formed in the target groove, wherein the copper electroplating current density is 5ASD and the copper electroplating time is 720s;

[0019] A tin plating layer is formed on the electroplated copper layer using tin plating technology. The tin plating current density is 2ASD and the tin plating time is 200s.

[0020] The conductive layer includes an electroplated copper layer and a tin plating layer.

[0021] In this embodiment, equipment parameter configurations for copper electroplating technology and tin electroplating technology are provided respectively. Under the corresponding parameter configuration, it is more conducive to the formation of grid lines and can also meet the high-precision processing requirements. Furthermore, copper electroplating technology is first used to form an electroplated copper layer, and then a tin plating layer is formed on the electroplated copper layer. This can better improve the welding performance and prevent the copper grid lines from being oxidized.

[0022] In one alternative implementation, the mask lines are paraffin lines.

[0023] In this embodiment, paraffin wax, which meets the condensation requirements, is preferentially used as the printing material for the inkjet printer. Because paraffin wax can effectively print inside the grooves, a tight bond is formed between the mask lines and the groove walls, ensuring that no gaps remain between the paraffin wax and the groove walls.

[0024] In one alternative implementation, the paraffin wires cover 2%-5% of the area on the substrate.

[0025] In one alternative embodiment, when the material used for the mask lines is paraffin wax that meets a preset solidification rate, removing the mask lines includes:

[0026] Butylene glycol and potassium hydroxide were used to remove the mask lines at 50°C.

[0027] When the printing material is paraffin, BDG+KOH is used to remove the paraffin at 50°C. Since only one paraffin line needs to be printed in each electroplating area, the amount of paraffin used can be significantly reduced, and the cost of dewaxing and the generation of wastewater can also be reduced.

[0028] In one alternative implementation, the thickness of the seed layer ranges from 50 nm to 1000 nm.

[0029] In this embodiment, a suitable seed layer thickness can be selected based on the required product performance, thereby improving product reliability.

[0030] In one optional implementation, removing the seed layer outside the conductive layer includes:

[0031] The seed layer is removed using CuCl2 alkaline etching solution or sulfuric acid hydrogen peroxide.

[0032] Using an alkaline CuCl2 etching solution can quickly remove the seed layer, improve etching return efficiency, and avoid damage to other materials. Sulfuric acid and hydrogen peroxide, on the other hand, are environmentally friendly and ensure the cleanliness of the substrate surface. The appropriate etching solution can be selected based on specific needs and application scenarios to better meet product requirements.

[0033] In one alternative implementation, the minimum width of the target groove is 3 μm.

[0034] Because the laser spot is adjustable, meaning the focusing size and ink droplet size are adjustable, the width of the target groove, i.e. the width of the electroplating grid line, can be flexibly adjusted. The minimum electroplating grid line can be 3μm, and the process has good stability and high inkjet printing efficiency.

[0035] Secondly, the present invention provides a photovoltaic cell, wherein the grid lines of the photovoltaic cell are prepared using any of the grid line preparation methods described above.

[0036] It should be noted that the photovoltaic cell provided by this invention uses a grid line fabrication method to prepare the grid lines. Therefore, for the beneficial effects of the photovoltaic cell, please refer to the description of the corresponding beneficial effects of the grid line fabrication method above, and will not be repeated here. Attached Figure Description

[0037] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 This is a schematic flowchart of a gate line fabrication method according to an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the structure after a seed layer has been deposited on a substrate according to an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of the structure after an insulating layer is formed on the seed layer according to an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram of the structure of the initial groove according to an embodiment of the present invention;

[0042] Figure 5 This is a schematic diagram of the structure after printing the mask line according to an embodiment of the present invention;

[0043] Figure 6 This is a schematic diagram of the structure after printing a mask line in the middle of the initial groove according to an embodiment of the present invention;

[0044] Figure 7 This is a schematic diagram of the structure after forming an electroplated copper layer according to an embodiment of the present invention;

[0045] Figure 8 This is a schematic diagram of the structure after removing the insulating layer according to an embodiment of the present invention;

[0046] Figure 9 This is a schematic diagram of the structure after removing the mask lines according to an embodiment of the present invention;

[0047] Figure 10 This is a schematic diagram of the structure after removing the seed layer outside the electroplated copper layer according to an embodiment of the present invention;

[0048] Reference numerals: 1-substrate, 2-seed layer, 3-insulating layer, 4-initial groove, 5-mask line, 6-target groove, 7-conductive layer, 8-gate line. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0050] This embodiment provides a gate line fabrication method, which can be executed by corresponding production line equipment, such as... Figure 1 The diagram shown is a flowchart of a gate line fabrication method according to an embodiment of the present invention, which includes the following steps:

[0051] Step S101: Deposit a seed layer 2 on substrate 1, referring to... Figure 2 As shown. Specifically, the substrate can be a silicon wafer or other materials, and a copper seed layer 2 can be deposited on the bare substrate 1 using PVD (Physical Vapor Deposition) technology.

[0052] Step S102, an insulating layer 3 is formed on the seed layer 2, as shown in the figure. Figure 3 As shown. An insulating layer 3 can be formed on the seed layer 2 by spin coating, screen printing, coating, inkjet printing, etc. The thickness of the insulating layer 3 can be about 15μm. In addition, the insulating layer 3 used in this embodiment can be any of the following: paraffin wax, polyimide, ink, but is not limited to the above insulating materials.

[0053] Step S103: An initial groove 4 is formed on the insulating layer 3. The depth of the initial groove 4 is equal to the thickness of the insulating layer 3. (Refer to...) Figure 4 As shown. Specifically, laser ablation technology can be used to form an initial groove 4 on the insulating layer 3. Of course, this embodiment is not limited to using laser ablation technology. For example, the first laser ablation can form a groove with a width of about 65μm, and the ablation depth is the same as the thickness of the insulating layer 3, which can be about 15μm. This step can form an initial groove 4 of different sizes according to the minimum focusing size of the laser, and is not limited to a width of 65μm. It can be adjusted according to the focusing capability of the laser equipment.

[0054] Step S104: Print a mask line 5 within the initial groove 4 to obtain a target groove 6 of a preset width, referring to... Figure 5As shown. Specifically, an inkjet printer can be used to print a mask line 5 within the initial groove 4. However, this embodiment is not limited to using an inkjet printer. The preset width can be the target width of the target groove 6 determined by the user. The width of the target groove 6 can be determined by adjusting the width of the initial groove 4 and the width of the mask line 5. The line width of the mask line 5 can be determined by the droplet diameter of the inkjet printer. In this embodiment, an inkjet printer can be used for inkjet printing, and the printing material can be a hot-melt material such as paraffin wax or ink. Of course, besides… Figure 5 The position of the target groove relative to the mask line shown is referenced. Figure 6 As shown, depending on the design requirements, a mask line can also be printed in the middle of the initial groove so that the target groove is located on both sides of the mask line, etc.

[0055] Using the example above, a mask line 5 can be printed in an initial groove 4 with a width of 65μm using an inkjet printer. The droplet diameter of the inkjet printer can be adjusted; for example, with a droplet diameter of 45μm, printing a mask line 5 in the initial groove 4 will form a target groove 6 with a width of approximately 20μm. The droplet diameter of the inkjet printer is determined by the printhead selected by the user; the droplet diameter can be determined based on the selected printhead size.

[0056] Step S105: Electroplating is performed in the target groove 6 to form a conductive layer 7, as shown in the figure. Figure 7 As shown, the conductive layer is the conductive line formed on the surface of the photovoltaic cell.

[0057] Step S106: Sequentially remove the insulating layer 3, mask lines 5, and the seed layer 2 outside the conductive layer 7 region to form the gate line 8. (Refer to...) Figure 8 The diagram shown is a schematic image after removing insulation layer 3. (Refer to...) Figure 9 The diagram shown is a schematic image after removing mask line 5. (Refer to...) Figure 10 The diagram shown is a schematic of the gate line 8 obtained after removing the seed layer 2 outside the conductive layer 7 region. An alkaline solution can be used to remove the insulating layer 3.

[0058] In related technologies, the surface of the insulating layer is typically ablated directly by laser to form a pre-plated patterned mask. However, laser direct writing technology is limited by the optical focusing size of the laser equipment, preventing the formation of finer grid line structures. Alternatively, inkjet printing technology can be used to directly print a mask on the surface of the insulating layer to protect the non-plated areas and form a pre-plated patterned mask, followed by copper plating in the pre-plated areas. However, during inkjet printing, the large printing area is susceptible to environmental temperature, substrate temperature, and printing errors, resulting in gaps in the non-plated areas, meaning incomplete coverage and over-plating during the electroplating process. Furthermore, ink droplets can spread too large, covering the pre-plated areas and leading to under-plating or even complete failure to plate metal. Therefore, inkjet printing technology has poor stability, and the minimum thickness of the electroplated grid lines can only be 18μm, preventing the formation of finer grid line structures.

[0059] In this embodiment, laser and inkjet technologies are combined. First, laser ablation is used to form an initial groove on the insulating layer. Then, an inkjet printer is used to print a mask line within the initial groove, obtaining a target groove of a preset width. Electroplating is then performed within the target groove to form the grid structure. The grid fabrication method provided in this embodiment is not constrained by the laser optical focusing size, allowing for flexible adjustment of the grid width according to actual needs and precise control of the grid width, achieving high precision. Furthermore, the fabrication process only requires printing one mask line within the target groove, resulting in a smaller printing area compared to directly printing a mask layer on the substrate surface. The printing area accounts for only 2%-5% of the total substrate area, significantly improving the efficiency and process stability of inkjet printing. This greatly reduces the risk of under-plating or over-plating due to the poor stability of inkjet technology, thereby reducing the risk of affecting battery efficiency.

[0060] In some alternative embodiments, an initial groove 4 is formed on the insulating layer 3 using laser ablation technology. Forming the initial groove 4 on the insulating layer 3 using laser ablation technology includes:

[0061] Determine the focusing size of the laser device, which is used to determine the size of the initial groove 4.

[0062] Taking CO2 laser equipment as an example, currently available CO2 laser equipment can only achieve a minimum optical focusing depth of 35μm. The minimum width of the grid line formed by a single laser ablation on the insulating layer is also greater than 35μm, and the smaller the focusing depth, the higher the equipment cost. Furthermore, this size is still too large for photovoltaic grid lines, resulting in a large shading area and affecting the final efficiency of the battery. Therefore, within the limited optical focusing range, the minimum focusing size of the laser equipment can be determined first. The initial groove 4 can be ablated based on this minimum focusing size, further reducing the amount of subsequent printing material used and lowering the manufacturing cost.

[0063] In some alternative embodiments, an electroplating technique is used to electroplat the target groove 6 to form a conductive layer 7, including:

[0064] Using copper electroplating technology, a copper electroplating layer is first formed in the target groove 6, wherein the copper electroplating current density is 5ASD and the copper electroplating time is 720s;

[0065] A tin plating layer is formed on the electroplated copper layer using tin plating technology. The tin plating current density is 2ASD and the tin plating time is 200s.

[0066] The conductive layer 7 includes an electroplated copper layer and a tin plating layer.

[0067] In this embodiment, equipment parameter configurations for copper electroplating technology and tin electroplating technology are provided respectively. Under the corresponding parameter configuration, it is more conducive to the formation of the grid line 8 and can also meet the high-precision processing requirements. Furthermore, copper electroplating technology is first used to form an electroplated copper layer, and then a tin plating layer is formed on the electroplated copper layer. This is more conducive to improving welding performance and preventing the copper grid line from being oxidized.

[0068] In some alternative implementations, the mask line 5 is a paraffin line. Specifically, the paraffin used can be paraffin that meets the printing requirements, that is, paraffin that meets the condensation requirements. Of course, other hot-melt materials such as ink can also be used.

[0069] Considering the solidification speed and printing performance of the printing material, this embodiment preferentially uses paraffin wax, which meets the condensation requirements, as the printing material for the inkjet printer. Because paraffin wax can effectively print inside the grooves, a tight bond is formed between the mask lines and the groove walls, ensuring that no gaps remain between the paraffin wax and the groove walls.

[0070] In some alternative implementations, the area of ​​the paraffin wire on the substrate 1 is 2%-5%.

[0071] Using the method in this embodiment, only one mask line needs to be printed in the target groove during the preparation process. Compared with printing a mask directly on the surface of the insulating layer, the printing area is smaller, that is, the printing area only accounts for 2%-5% of the total substrate area. This significantly improves the efficiency and process stability of inkjet printing, and greatly reduces the situation of under-plating or over-plating due to the poor stability of inkjet technology, thereby reducing the risk of affecting battery efficiency.

[0072] Inkjet printheads are consumables, prone to clogging, and expensive. The paraffin wax required for printing to meet condensation requirements is also expensive, and removing paraffin wax requires a large amount of organic reagents, increasing wastewater treatment costs and causing environmental pollution.

[0073] In this embodiment, the laser ablation and inkjet printing technology used only requires printing one line of paraffin wax if paraffin wax is used as the printing material. This reduces the amount of paraffin wax needed to meet the condensation requirements and also reduces the amount of dewaxing solution used. This not only lowers the material cost but also reduces the pressure on subsequent wastewater treatment.

[0074] In some alternative implementations, when the mask line 5 is a paraffin line, removing the mask line 5 includes:

[0075] Butanediol and potassium hydroxide can be used to remove mask line 5 at 50°C.

[0076] Using BDG+KOH at 50℃ to remove paraffin significantly reduces paraffin consumption, as only one paraffin line needs to be printed in each electroplating area. This also reduces dewaxing costs and wastewater generation. In contrast, related technologies using inkjet printing to form grid lines require large-area printing in non-electroplating areas, necessitating large paraffin consumption, generating significant wastewater, resulting in high costs, low machine efficiency, and poor process stability.

[0077] In some alternative implementations, seed layer 2 is metallic copper.

[0078] Metallic copper has good electrical conductivity, providing a good conductive base that facilitates subsequent electroplating processes. Furthermore, alkaline etching solutions such as CuCl2 and sulfuric acid / hydrogen peroxide are commonly used to remove the copper seed layer, preferentially removing it without significantly affecting the surrounding copper plating areas.

[0079] In some alternative implementations, the thickness of the seed layer 2 ranges from 50 nm to 1000 nm.

[0080] In this embodiment, the appropriate seed layer thickness can be selected according to the required product performance, thereby improving product reliability. Generally, if the seed layer is too small, it will be corroded by the electroplating solution, affecting the electroplating effect and thus the uniformity and adhesion of the gate lines; if the seed layer is too thick, the seed layer cost will increase, the etching time will increase, and side etching will occur, thus affecting the morphology of the gate lines.

[0081] In some alternative embodiments, removing the seed layer 2 outside the conductive layer 7 region includes:

[0082] Seed layer 2 was removed using CuCl2 alkaline etching solution or sulfuric acid hydrogen peroxide.

[0083] In this embodiment, the use of CuCl2 alkaline etching solution can quickly remove seed layer 2, improve etching return efficiency, and avoid damage to other materials. Sulfuric acid and hydrogen peroxide are environmentally friendly and can ensure the cleanliness of the substrate surface. A suitable etching solution can be selected based on specific needs and application scenarios to better meet product requirements.

[0084] In some alternative embodiments, the thickness of the insulating layer 3 ranges from 8 μm to 40 μm.

[0085] In this embodiment, a wide range of insulating materials are selected, and the requirements for the uniformity of the formed insulating layer are relatively low. Therefore, more methods for forming the insulating layer are used. Generally, a 15μm insulating layer 3 is preferred, as this thickness can provide good insulation performance and effectively protect the stability of the seed layer.

[0086] In some alternative embodiments, the width of the initial groove 4 is 35 μm to 70 μm, and the depth of the initial groove 4 is 8 μm to 40 μm.

[0087] In this embodiment, laser ablation is performed on an insulating layer 3 with a thickness ranging from 8μm to 40μm. Therefore, the depth of the initial groove 4 can be 8μm to 40μm. The width of the initial groove 4 depends on the focusing size of the laser ablation. If the focusing size of the laser ablation is 65μm, then the width of the initial groove 4 is 65μm. The focusing size of the laser ablation varies depending on different laser equipment, process requirements, and material properties, and is generally between 35μm and 70μm.

[0088] In some alternative implementations, the minimum width of the target groove 6 is 3 μm.

[0089] In this embodiment, since the focusing size of laser ablation and the droplet diameter can be adjusted as needed, that is, the size of the initial groove 4 and the size of the mask line 5 can both be adjusted, the width of the grid line 8 has a large adjustable range. Furthermore, due to the stability of the inkjet printing droplet diameter and the influence of the bonding force between the droplet and the seed layer, the minimum width of the target groove obtained using the grid line preparation method provided in this embodiment can be 3 μm, meaning the minimum grid line width can reach 3 μm.

[0090] Because the fabrication methods in related technologies are easily affected by factors such as the temperature uniformity of the inkjet printing stage (the carrier unit used to support the substrate to be printed), the ink droplet solidification rate, and slight disturbances in the surrounding environment, the minimum thickness of the electroplated grid lines can currently be 18μm while ensuring inkjet efficiency.

[0091] This application only requires an insulating layer and a small amount of paraffin lines to protect the non-electroplated areas. The insulating layer can be made of ordinary paraffin or ordinary materials, and the paraffin used for the mask lines only needs to meet the printing requirements. Only one paraffin line is printed in each electroplating area. Compared with printing a mask directly on the surface of the insulating layer, the printing area is smaller, accounting for only 2%-5% of the total substrate area. The cost of wax is greatly reduced, and the cost of wax removal is also greatly reduced. In addition, since the laser spot and ink droplet size are adjustable, the width of the electroplating grid line can be flexibly adjusted. The minimum electroplating grid line can be 3μm, and the process stability is good and the inkjet printing efficiency is high.

[0092] This invention can achieve copper grid lines with a minimum width of 3μm and arbitrary height without the need for traditional, complex exposure and development techniques, resulting in lower costs, simpler processes, a wider selection of insulating layer materials, and lower requirements for the uniformity of the formed insulating layer, thus allowing for more methods to be used to form the insulating layer. The width and height of the grid lines are highly adjustable, requiring simple equipment and lower material costs. Compared to direct inkjet printing technology, it offers higher precision, effectively improving inkjet production efficiency while reducing costs; compared to directly using laser technology, it can form finer grid lines.

[0093] This embodiment also provides a photovoltaic cell, wherein the grid lines of the photovoltaic cell are prepared using the grid line preparation method described in any of the above embodiments.

[0094] A further description of the gate line fabrication method is the same as that in the corresponding embodiments described above, and will not be repeated here.

[0095] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for fabricating a gate line, characterized in that, The method includes: A seed layer (2) is deposited on the substrate (1); An insulating layer (3) is formed on the seed layer (2); An initial groove (4) is formed on the insulating layer (3) using laser ablation technology; wherein: the focusing size of the laser device is determined, the focusing size being used to determine the size of the initial groove (4); the depth of the initial groove (4) is equal to the thickness of the insulating layer (3); A mask line (5) is printed in the initial groove (4) to obtain a target groove (6) of a preset width; the line width of the mask line is determined by the ink droplet diameter of the inkjet printer. Electroplating is performed inside the target groove (6) to form a conductive layer (7); The seed layer (2) outside the insulating layer (3), the mask line (5), and the conductive layer (7) is removed in sequence to form the gate line (8) of the preset width.

2. The method according to claim 1, characterized in that, The process of electroplating within the target groove (6) to form a conductive layer (7) using electroplating technology includes: Using copper electroplating technology, a copper electroplating layer is first formed in the target groove (6), wherein the copper electroplating current density is 5ASD and the copper electroplating time is 720s; A tin plating layer is formed on the electroplated copper layer using tin plating technology, wherein the tin plating current density is 2ASD and the tin plating time is 200s. The conductive layer (7) includes the electroplated copper layer and the tin plating layer.

3. The method according to claim 1, characterized in that, The mask line (5) is a paraffin line.

4. The method according to claim 3, characterized in that, The area of ​​the paraffin wire on the substrate (1) accounts for 2%-5%.

5. The method according to claim 3, characterized in that, The removal of the mask line (5) includes: The mask lines (5) were removed at 50°C using butanediol and potassium hydroxide.

6. The method according to claim 1, characterized in that, The thickness of the seed layer (2) ranges from 50 nm to 1000 nm.

7. The method according to claim 2, characterized in that, The removal of the seed layer (2) from the conductive layer (7) includes: The seed layer (2) was removed using CuCl2 alkaline etching solution or sulfuric acid hydrogen peroxide.

8. The method according to any one of claims 1 to 7, characterized in that, The minimum width of the target groove (6) is 3 μm.

9. A photovoltaic cell, characterized in that, The grid lines of the photovoltaic cell are prepared using the grid line preparation method described in any one of claims 1 to 8.

Images