Soft contact printing method and soft contact printing mould for grid line slurry of photovoltaic cell

Abstract

The invention relates to the technical field of photovoltaics, and discloses a soft contact printing method and a soft contact printing mold for grid line slurry of a photovoltaic cell. The soft contact printing method comprises the following steps: placing a silicon wafer below a manufactured mold; the driving piece drives the printing head to move downwards to form a gap with the surface of the silicon wafer, and the printing head stops moving downwards; the magnetic field generator drives the propeller through magnetic field force to push grid line slurry in the slurry filling cavity to move downwards and overflow from the bottom face of the opening area. The printing head moves upwards, and the distance between the bottom face of the opening area and the surface of the silicon wafer is smaller than the distance that the propeller pushes the grid line slurry to move downwards, so that the overflowing grid line slurry is separated from the mold and makes contact with the surface of the silicon wafer; the magnetic field generator is closed, the printing head continues to move upwards, the grid line slurry is separated from the opening area, and the metal grid line with the cross section in a trapezoid shape with the narrow upper portion and the wide lower portion is manufactured on the surface of the silicon wafer after sintering. The metal grid line prepared by the method has the advantages of improving the height-width ratio, reducing the cost, improving the light reflection light utilization and improving the cell efficiency.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, and particularly relates to a soft contact printing method for a grid paste of a photovoltaic cell and a soft contact printing die. Background Art

[0002] At present, cost reduction and efficiency improvement of Topcon cells (the full name is Tunnel Oxide Passivating Contact, which is a photovoltaic cell with an N-type silicon substrate and realizes passivating contact through a tunneling oxide to improve cell performance) have become the main theme. Under the current high cost pressure, reducing the silver consumption (silver paste is mainly used to prepare metal grid lines or metal electrodes, but the cost of silver paste is high) has become one of the main means of cost reduction: mainly by reducing the number of grid lines (as shown in the publication number CN220253256U) and reducing the aspect ratio of the grid lines (as shown in the publication number CN113212017A). However, these cost reduction methods will cause loss of cell efficiency. For example, if the number of grid lines is reduced from the original 180 to 170, although this can reduce the amount of silver paste used and lower the cost, it will also cause loss of FF (fill factor), thereby reducing the cell efficiency.

[0003] Moreover, to control the metallization cost, the existing metallization method for metal grid lines or metal electrodes is: usually, grid paste (such as silver paste) is first printed on the metallization grid line area on the surface of the silicon wafer, and then high-temperature sintering is carried out to form a patterned metal grid line or metal electrode. Among them, as shown in the publication number CN113212017A, the printing of grid paste is usually carried out by screen printing; its basic principle is to transfer the grid paste to the silicon wafer through the mesh holes or openings opened in the screen printing plate (i.e., the screen). During screen printing, the screen is placed at a predetermined position on the surface of the silicon wafer, grid paste is poured at one end of the screen, a squeegee applies a downward pressure to the grid paste part on the screen, and moves towards the other end of the screen, so that the grid paste is extruded onto the silicon wafer through the mesh holes or openings of the screen.

[0004] However, during the process of the squeegee applying a downward pressure to the grid paste part on the screen, the screen is prone to deformation and offset, and there will be a phenomenon of widening of the grid paste (that is, the line width of the grid paste on the surface of the silicon wafer is usually greater than the opening width of the actual screen). Therefore, it is difficult to further reduce the line width of the grid paste produced by the screen printing method. Furthermore, with the existing screen printing method, it is impossible to ensure both the single consumption of the grid paste and the cell efficiency at the same time, and it is difficult to balance the cost and efficiency of the cell. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a soft contact printing method for a grid paste of a photovoltaic cell and a soft contact printing die.

[0006] Based on this, the present invention discloses a soft contact printing method for photovoltaic cell grid line paste, which comprises the following steps:

[0007] S1. Manufacturing a mold: The mold includes a printing head and a driving member connected to the printing head, and the driving member drives the printing head to move up and down; the printing head includes a pusher, a magnetic field generator for driving the pusher to move downward, and a paste filling cavity for accommodating the grid line paste; the pusher is installed above the paste filling cavity; the paste filling cavity includes a plurality of opening areas for the grid line paste to overflow from its bottom surface and be printed onto the surface of the silicon wafer, and the cross-section of the opening area is a trapezoid with a narrow upper part and a wide lower part;

[0008] S2. Placing the grid line paste in the paste filling cavity and placing the silicon wafer below the mold so that the metallized grid line area on the surface of the silicon wafer is aligned with the opening area;

[0009] S3. The driving member drives the printing head to move downward to make the printing head approach the surface of the silicon wafer. When the printing head moves downward to have a certain gap with the surface of the silicon wafer, the printing head stops moving downward;

[0010] S4. The magnetic field generator drives the pusher to move downward through magnetic force so that the pusher pushes the grid line paste in the paste filling cavity to move downward and overflow from the bottom surface of the opening area;

[0011] S5. The driving member drives the printing head to move upward and makes the distance between the bottom surface of the opening area and the surface of the silicon wafer less than the distance that the pusher pushes the grid line paste to move downward, so that the overflowed grid line paste breaks away from the mold and contacts the surface of the silicon wafer;

[0012] S6. Closing the magnetic field generator, and the driving member continues to drive the printing head to move upward to completely separate the grid line paste from the opening area. After sintering, a metal grid line with a trapezoidal cross-section with a narrow upper part and a wide lower part is formed on the surface of the silicon wafer.

[0013] Preferably, the number of the opening areas is the same as the number of the metal grid lines on the surface of the silicon wafer, and the number of the opening areas is 150 - 320.

[0014] Further preferably, the number of the opening areas is 200 - 280.

[0015] Preferably, the upper side length of the trapezoid of the cross-section of the opening area is 4 - 5 μm, the lower side length of the trapezoid is 7 - 9 μm, and the height of the trapezoid is 4 - 12 μm.

[0016] Preferably, the magnetic field generator includes a wire, a fixing member installed above the pusher, and a magnetic structure provided on the pusher; the wire is connected to an external power supply; the fixing member is fixedly connected to the wire to install the wire above the pusher through the fixing member, and the wire is located above the magnetic structure.

[0017] Preferably, the pusher is a rubber pusher that fits against the side wall of the slurry filling cavity.

[0018] Preferably, in step S6, the width of the metal grid line is 5 - 12 μm and its height is 3 - 10 μm.

[0019] More preferably, in step S3, when the printing head moves down to a gap of 2 - 3 μm from the surface of the silicon wafer, the printing head stops moving down.

[0020] More preferably, the distance that the pusher pushes the grid line slurry down is the height of the metal grid line before sintering;

[0021] When the height of the metal grid line before sintering is 6 - 10 μm, the upward movement distance of the printing head in step S5 is 3 - 7 μm.

[0022] The present invention also discloses a soft - contact printing mold for photovoltaic cell grid line slurry, which is the mold used for the soft - contact printing method of photovoltaic cell grid line slurry described above in the content of the present invention.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] Compared with the existing screen printing of the screen plate (the existing screen plate has a hard contact with the surface of the silicon wafer: the screen plate needs to be placed on the surface of the silicon wafer, and the squeegee needs to apply a downward pressure on the grid line slurry part of the screen plate, and the screen plate is prone to deformation and deviation), by using the soft - contact printing method of the present invention, soft - contact printing of the grid line slurry on the surface of the silicon wafer can be realized, and the grid line slurry will not spread during the printing process. Therefore, the phenomenon of grid line slurry broadening in the existing screen - plate screen printing can be effectively avoided, and grid line slurry with a finer width can be printed on the surface of the silicon wafer. After sintering, extremely fine and extremely high metal grid lines can be obtained, and the aspect ratio of the metal grid lines can be further increased; this can not only further reduce the usage amount of the grid line slurry and the cost of the metal grid lines, but also the finer - width metal grid lines have less light shielding, and can increase the absorption and utilization of sunlight by the battery, which helps to improve the battery efficiency.

[0025] Moreover, compared with the existing grid line slurry printing method powered by electricity, in the present invention, under the action of the magnetic field force, the pusher pushes the grid line slurry down, which can further save energy, reduce costs, improve the thrust control accuracy and printing accuracy, and also improve the propulsion efficiency and printing efficiency.

[0026] At the same time, the present invention also cooperates with the use of an opening area with a trapezoidal cross - section that is narrower at the top and wider at the bottom, so that the cross - section of the metal grid line is also trapezoidal with a narrower top and wider bottom; therefore, the reflection and reuse of sunlight on the side of the metal grid line can be increased, more photocurrent can be collected, and the battery efficiency can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic three - dimensional structure diagram of a soft - contact printing device for a photovoltaic cell grid line paste in this embodiment.

[0028] Figure 2 Schematic side - view structure diagram of a soft - contact printing device for a photovoltaic cell grid line paste in this embodiment, where the magnetic structure is provided on the thruster.

[0029] Figure 3 Schematic cross - sectional structure diagram of a soft - contact printing method for a photovoltaic cell grid line paste in this embodiment after being processed by step S5.

[0030] Explanation of the reference numerals in the drawings: Driving member 1; Printing head 2; Magnetic field generator 21; Conducting wire 211; Fixing member 212; Magnetic structure 213; Thruster 22; Paste filling cavity 23; Opening area 231; Silicon wafer 3; Metal grid line 31 before sintering. Detailed implementation manners

[0031] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific implementation manners.

[0032] Embodiment

[0033] A soft - contact printing method for a photovoltaic cell grid line paste in this embodiment is as follows. Refer to Figures 1-3 , which includes the following steps:

[0034] Step S1: Fabricate a soft - contact printing mold for a photovoltaic cell grid line paste as shown below in this embodiment:

[0035] The soft - contact printing mold includes a printing head 2 and a driving member 1; the driving member 1 is connected to the printing head 2 to drive the printing head 2 to move up and down, so that the printing head 2 can approach or move away from the surface of the silicon wafer 3. The driving member 1 is preferably a motor.

[0036] Among them, the printing head 2 includes a thruster 22, a magnetic field generator 21, and a paste filling cavity 23 for accommodating the grid line paste. The magnetic field generator 21 is connected to the thruster 22 to drive the thruster 22 to move downward. The thruster 22 is installed at the upper part of the paste filling cavity 23, and the paste filling cavity 23 includes a plurality of opening areas 231 arranged at intervals in sequence (such as Figure 1 , 3As shown in the figure; in this way, under the action of the magnetic field force, the pusher 22 can push the grid line paste in the paste filling cavity 23 downward, so that the downward-moving grid line paste overflows from the bottom surface of the opening area 231 and is printed on the surface of the silicon wafer 3. Further, the cross-section of the opening area 231 (this cross-section refers to the cross-section in the width direction of the opening area 231) is a trapezoid with a narrow upper part and a wide lower part, so that the cross-section of the printed and sintered metal grid line is also a trapezoid with a narrow upper part and a wide lower part (as Figure 3 shown).

[0037] During the existing screen printing, the screen needs to be placed on the surface of the silicon wafer, and a downward pressure needs to be applied to the grid line paste part on the screen with a squeegee, so that the grid line paste is extruded through the mesh holes of the screen onto the surface of the silicon wafer. Therefore, during the existing screen printing process, the existing screen is in hard contact with the surface of the silicon wafer. During the process of applying a downward pressure to the grid line paste part on the screen with a squeegee, the screen is prone to deformation and offset. Furthermore, the existing screen printing is prone to the phenomenon of grid line paste broadening (that is, the line width of the grid line paste on the surface of the silicon wafer is usually greater than the opening width of the actual screen).

[0038] However, the mold of this embodiment, through the mutual cooperation of the above-mentioned driving member 1, magnetic field generator 21, pusher 22, paste filling cavity 23 and opening area 231; during the printing process, the driving member 1 can first drive the printing head 2 to approach (but not contact) the surface of the silicon wafer 3, and then make the pusher 22 push the grid line paste in the paste filling cavity 23 downward under the action of the magnetic field force and overflow from the bottom surface of the opening area 231, and the driving member 1 then drives the printing head 2 to move upward, so that the overflowing grid line paste separates from the mold and contacts the surface of the silicon wafer 3. In this way, during the process of printing the grid line paste on the surface of the silicon wafer 3 using this mold, the entire mold (such as the printing head 2) does not contact the surface of the silicon wafer 3, and the mold does not need to apply a downward pressure to the printed grid line paste; that is, using this mold can enable the grid line paste to achieve soft-contact printing on the surface of the silicon wafer 3, and there will be no broadening of the grid line paste during the printing process. Therefore, it can effectively avoid the phenomenon of grid line paste broadening in the existing screen printing, and can print grid line paste with a finer width on the surface of the silicon wafer 3. After sintering, extremely fine and extremely high metal grid lines can be obtained, which can further improve the aspect ratio of the metal grid lines; furthermore, it can not only further reduce the usage of grid line paste (such as silver paste) and the cost of metal grid lines, but also increase the absorption and utilization of sunlight by the battery (because the width of the metal grid lines is finer, so the shielding of sunlight by the metal grid lines can be further reduced), which helps to improve the battery efficiency.

[0039] Moreover, compared with the existing grid line paste printing method driven by electricity, in this embodiment, through the cooperation of the magnetic field generator 21 and the pusher 22, the pusher 22 is pushed to move the grid line paste downward under the action of the magnetic field force, which can further save energy, reduce costs, improve the thrust control accuracy and printing accuracy, and also improve the propulsion efficiency and printing efficiency.

[0040] Meanwhile, this embodiment also cooperates with the use of the opening area 231 with a trapezoidal cross-section that is narrower at the top and wider at the bottom, so that the cross-section of the printed and sintered metal grid line is also trapezoidal with a narrower top and wider bottom; therefore, it can also increase the reflection and reuse of sunlight on the side of the metal grid line, collect more photocurrent, and further improve the battery efficiency.

[0041] In practice, a mold with the same number of opening areas 231 is made according to the number of metal grid lines on the surface of the silicon wafer 3. The number of opening areas 231 can be 150 - 320.

[0042] In this embodiment, the number of opening areas 231 is preferably 200 - 280. On the premise of making extremely thin and high metal grid lines and reducing the cost of metal grid lines, the number of metal grid lines on the surface of the silicon wafer 3 can be appropriately increased to increase the metal grid line density on the surface of the silicon wafer 3, and the fill factor of the battery can be improved through extremely thin and high-density grid lines, further improving the battery efficiency.

[0043] Specifically, the upper side length of the trapezoid of the cross-section of the opening area 231 is 4 - 5 μm, the lower side length of the trapezoid of the cross-section of the opening area 231 is 7 - 9 μm, and the height of the trapezoid of the cross-section of the opening area 231 is 4 - 12 μm. In this way, it is ensured that the printed and sintered metal grid line by the soft contact printing method of this embodiment has the advantages of being extremely thin and high; the width of the metal grid line is 5 - 12 μm, and the height of the metal grid line is 3 - 10 μm (preferably 6 - 10 μm).

[0044] After printing and sintering, due to the influence of factors such as gravity, the width of the metal grid line is usually slightly larger than the width of the opening area 231, and the height of the metal grid line is usually slightly smaller than the height of the opening area 231.

[0045] Specifically, referring to Figures 1-2 , the magnetic field generator 21 includes a wire 211, a fixing member 212, and a magnetic structure 213 provided on the thruster 22. For example, the magnetic structure 213 can be a magnetic material layer provided on the upper surface of the thruster 22 (such as Figure 2As shown. The fixing member 212 is installed above the thruster 22, and the fixing member 212 is fixedly connected to the wire 211; preferably, both ends of each wire 211 can be fixedly connected to a fixing member 212, so as to firmly install the wire 211 above the thruster 22 through the fixing member 212; the number of wires 211 can be several, and several wires 211 are spaced above the thruster 22, and several wires 211 are electrically connected to an external power supply after being connected in parallel and / or in series, so as to be powered by the external power supply; moreover, the wire 211 is located above the magnetic structure 213. In this way, a constant magnetic field can be generated above the thruster 22 through a constantly changing current, and the thruster 22 can accurately and efficiently push the grid line paste in the paste filling cavity 23 to move downward, overflow and contact the surface of the silicon wafer 3 under the action of the constant magnetic field force, and then the grid line paste can be accurately and efficiently soft-contact printed on the surface of the silicon wafer 3.

[0046] During the actual working process, the magnetic structure 213 will move downward together with the thruster 22 and the grid line paste in the paste filling cavity 23, while the wire 211 and the fixing member 212 do not move downward together with the thruster 22 and the grid line paste in the paste filling cavity 23. The material of the magnetic structure 213 is a magnet or other materials containing permanent magnets (such as nickel magnet, nickel iron magnet, etc.).

[0047] Specifically, the thruster 22 is preferably a rubber thruster 22 that fits against the side wall of the paste filling cavity 23. The rubber thruster 22 can fit tightly against the side wall of the paste filling cavity 23, which can ensure sufficient and effective extrusion of the grid line paste in the paste filling cavity 23 to effectively ensure the downward movement of the grid line paste.

[0048] Step S2: Place the grid line paste in the paste filling cavity 23, and place the silicon wafer 3 under the mold so that the metallized grid line area on the surface of the silicon wafer 3 is aligned with the opening area 231.

[0049] Step S3: The driving member 1 drives the printing head 2 to move downward to make the printing head 2 approach the surface of the silicon wafer 3. When the printing head 2 moves downward to a certain gap from the surface of the silicon wafer 3, the printing head 2 stops moving downward. There is such a gap between the printing head 2 and the surface of the silicon wafer 3 so that the mold can be used to achieve soft-contact printing of the grid line paste on the surface of the silicon wafer 3.

[0050] Specifically, in step S3, when the gap between the printing head 2 and the surface of the silicon wafer 3 is 2-3 μm, the printing head 2 stops moving downward. The size of this gap should not be too large, so as to avoid the deformed grid line paste overflowing and falling from a high altitude onto the surface of the silicon wafer 3; the size of this gap should not be too small, so as to avoid the grid line paste overflowing later being affected by the extrusion between the thruster 22 and the surface of the silicon wafer 3, which will affect the further improvement of the aspect ratio of the sintered metal grid line.

[0051] Step S4: The magnetic field generator 21 drives the thruster 22 to move downward through the generated magnetic field, so that the thruster 22 pushes the grid line paste in the paste filling cavity 23 to move downward and overflow from the bottom surface of the opening area 231.

[0052] Step S5: The driving member 1 drives the printing head 2 to move upward, and makes the distance between the bottom surface of the opening area 231 and the surface of the silicon wafer 3 less than the distance that the thruster 22 pushes the grid line paste to move downward (the distance that the thruster 22 pushes the grid line paste to move downward is the height of the metal grid line 31 before sintering, and the height of the metal grid line 31 before sintering is the height of the grid line paste that is soft-contact printed on the surface of the silicon wafer 3 in the following step S6), so as to ensure that the overflowed grid line paste can break away from the mold and can contact the surface of the silicon wafer 3 (as Figure 3 shown), so that the contact force between the surface of the silicon wafer 3 and the grid line paste is greater than the sum of the frictional forces between the grid line pastes and between the grid line paste and the side wall of the opening area 231, so that the grid line paste and the opening area 231 can be more quickly and efficiently completely separated subsequently.

[0053] When the height of the metal grid line 31 before sintering is preferably 6-10 μm, the upward movement distance of the printing head 2 in step S5 is preferably 3-7 μm.

[0054] Step S6: Turn off the magnetic field generator 21, and the driving member 1 continues to drive the printing head 2 to move upward to completely separate the grid line paste from the opening area 231, so as to complete the soft-contact printing of the grid line paste on the surface of the silicon wafer 3; after sintering, a metal grid line with a trapezoidal cross-section that is narrower at the top and wider at the bottom is formed on the surface of the silicon wafer 3.

[0055] In summary, the mold of the present embodiment can perform the soft-contact printing of the photovoltaic cell grid line paste on the surface of the silicon wafer 3 as described in the above steps S1-S6. This can effectively avoid the phenomenon of grid line paste broadening in the existing screen printing. After sintering, extremely fine and extremely high metal grid lines can be obtained, which can further improve the aspect ratio of the metal grid lines, reduce the amount of grid line paste used, reduce the cost of the metal grid lines, and the thinner metal grid lines have less blockage of sunlight, and can also increase the absorption and utilization of sunlight by the battery, which helps to improve the battery efficiency; moreover, the thruster 22 of the mold pushes the grid line paste to move downward through the action of magnetic force. Compared with the existing grid line paste printing method using electric propulsion, it can further save energy, reduce costs, improve the thrust control accuracy and printing accuracy, and improve the propulsion efficiency and printing efficiency; at the same time, it can make the cross-section of the printed and sintered metal grid line be trapezoidal with a narrow top and a wide bottom, and can also increase the reflection and reuse of sunlight on the side of the metal grid line, collect more photocurrent, and further improve the battery efficiency.

[0056] In addition, on the premise of fabricating extremely thin and high metal grid lines and reducing the cost of metal grid lines, the number of metal grid lines on the surface of the silicon wafer 3 can be appropriately increased to increase the metal grid line density on the surface of the silicon wafer 3. By means of the extremely thin and high-density grid lines, the fill factor of the battery can be improved, and further the battery efficiency can be enhanced. Additionally, through the optimization of the gap in step S3 and the upward movement distance of the printing head 2 in step S5, the grid line paste can be more precisely and efficiently soft-contact printed on the surface of the silicon wafer 3, further improving the aspect ratio and quality of the metal grid lines.

[0057] Therefore, the metal grid lines fabricated by the soft-contact printing die and the soft-contact printing method used in this embodiment are more advantageous in terms of improving the aspect ratio, reducing the cost, enhancing light reflection and light utilization, improving the printing accuracy and printing efficiency, and enhancing the battery efficiency.

[0058] Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

[0059] The technical solutions provided by the present invention have been introduced in detail above. Specific examples are used herein to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A soft contact printing method for photovoltaic cell grid line paste, characterized in that: The steps include: S1. Making a mold: the mold includes a printing head and a driving member connected to the printing head, the driving member drives the printing head to move up and down; the printing head includes a propeller, a magnetic field generator driving the propeller to move downward, and a slurry filling cavity for accommodating gate line slurry; the propeller is installed at the upper part of the slurry filling cavity; the slurry filling cavity includes a plurality of opening areas for the gate line slurry to overflow from its bottom surface and then be printed on the surface of the silicon wafer, and the cross section of the opening area is a trapezoidal shape that is narrow at the top and wide at the bottom; S2, placing the gate line slurry in the slurry filling cavity, and placing the silicon wafer under the mold, so that the metallized gate line area on the surface of the silicon wafer is aligned with the opening area; S3, the driving member drives the printing head to move downward to bring the printing head close to the surface of the silicon wafer. When the printing head moves downward to a certain gap with the surface of the silicon wafer, the printing head stops moving downward; S4, the magnetic field generator drives the propeller to move downward through the magnetic field force, so that the propeller pushes the grid line slurry in the slurry filling cavity to move downward and overflow from the bottom surface of the opening area; S5, the driving member drives the printing head to move upward, and the distance between the bottom surface of the opening area and the surface of the silicon wafer is smaller than the distance that the pusher pushes the gate line slurry downward, so that the overflowed gate line slurry is separated from the mold and contacts the surface of the silicon wafer; S6. Turn off the magnetic field generator, and the driving part continues to drive the printing head upward to completely separate the gate line slurry from the opening area. After sintering, a metal gate line with a trapezoidal cross-section that is narrow at the top and wide at the bottom is obtained on the surface of the silicon wafer.

2. A method for soft contact printing of photovoltaic cell grid line paste according to claim 1, characterized in that: The number of the opening areas is the same as the number of metal gate lines on the surface of the silicon wafer, and the number of the opening areas is 150-320.

3. A method for soft contact printing of photovoltaic cell grid line paste according to claim 2, characterized in that: The number of the opening areas is 200-280.

4. The method for soft contact printing of photovoltaic cell grid line paste according to claim 1, characterized in that: The cross section of the opening area has a trapezoidal upper side length of 4-5 μm, a trapezoidal lower side length of 7-9 μm, and a trapezoidal height of 4-12 μm.

5. The soft contact printing method of photovoltaic cell grid line paste according to claim 1, characterized in that: The magnetic field generator includes a wire, a fixing installed above the thruster, and a magnetic structure provided on the thruster; the wire is connected to an external power source; the fixing is used to fix the wire so that the wire is installed above the thruster through the fixing, and the wire is located above the magnetic structure.

6. The method for soft contact printing of photovoltaic cell grid line paste according to claim 1, characterized in that: The propeller is a rubber propeller that fits the side wall of the slurry filling cavity.

7. The method for soft contact printing of photovoltaic cell grid line paste according to claim 1, characterized in that: In step S6, the width of the metal gate line is 5-12 μm and the height is 3-10 μm.

8. A method for soft contact printing of photovoltaic cell grid line paste according to claim 1 or 7, characterized in that: In step S3, when the printing head moves downward to a gap of 2-3 μm between the printing head and the surface of the silicon wafer, the printing head stops moving downward.

9. A method for soft contact printing of photovoltaic cell grid line paste according to claim 1 or 7, characterized in that: The distance that the propeller pushes the grid line slurry downward is the height of the metal grid line before sintering; When the height of the metal grid line before sintering is 6-10 μm, the upward movement distance of the printing head in step S5 is 3-7 μm.

10. A soft contact printing mold for photovoltaic cell grid line paste, characterized in that: It is a mold used in a soft contact printing method of a photovoltaic cell grid line paste as described in any one of claims 1 to 9.

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