Passivated back contact cell metallization process, silk-screen printing table and control method thereof

Abstract

The invention relates to the technical field of solar photovoltaic cells, in particular to a passivated back contact cell metallization process, a silk-screen printing table and a control method thereof. Specifically, the non-main grid structure is adopted, and the welding area is reserved for welding with components during the passivated back contact metallization process, which simplifies the isolation of P zone and N zone, greatly simplifying the difficulty of metallization of the passivated back contact cell structure. The welding yield of components is improved, the welding accuracy is solved, the CTM is improved, and the KWH cost is reduced. Based on it, the shading problem of the back main grid and the welding strip is reduced, and the double-sided ratio of the cell and the corresponding components is improved. And by improving the printing table and increasing the drying function, the printed grid line can be quickly cured and formed, which ensure the production capacity and effect of the cell.

Description

PASSIVATED BACK CONTACT CELL METALLIZATION PROCESS, SILK-SCREEN PRINTING TABLE AND CONTROL METHOD THEREOFField of the invention

[0001] The invention relates to the technical field of solar photovoltaic cells, in particular to a passivated back contact cell metallization process, a silk-screen printing table and a control method thereof.Background

[0002] In order to improve the proportion of photovoltaic power generation, cost reduction and efficiency are the two main lines of photovoltaic manufacturing. At present, the mainstream photovoltaic cells are crystalline silicon solar cells. The back contact structure (BC) solves the problem of shading the front gate line of the cell, improves the area utilization rate and greatly improves the appearance, efficiency and practical value of photovoltaic cells. The TBC structure cell superimposed with TOPCon technology has become one of the most potential new high-efficiency cell technologies due to its good compatibility with the traditional PERC cell production line and its obvious efficiency gain (The reported mass production efficiency>25.5%).

[0003] At present, the commonly used metallization process scheme of passivated back contact cell is: the P zone and the N zone are isolated on the back of the cell through insulation adhesive or finger structure, and then the N main gate for exporting electrons and the P main gate for exporting holes are printed; In this way, the N-type and P-type main gate are concentrated on the back, resulting in a very dense main gate, which is a great challenge for the control of welding accuracy and yield, as well as the guarantee of the component CTM (Cell to Module). In addition, the presence of an overly dense main grid on the back and welding tape leads to additional back shading which greatly limits the double-sided rate of the passivated back contact cells.

[0004] The information disclosed in the background technology section is intended only to enhance the understanding of the general background technology of the invention and should not be taken as an admission or in any way implied that the information constitutes prior art known to a person skilled in the art.Summary of the invention

[0005] The technical problem to be solved by the invention is to provide a metallization process of passivated back contact cell, in which the welding area is reserved for welding with modules during the passivated back contact metallization process, so as to simplify the module welding, reduce the main grids shading on the back of passivated back contact cell, simplify the metallization process, and optimize the module yield and CTM.

[0006] The above object of the present invention is achieved by the following technical solutions:

[0007] The invention relates to a metallization process for a passivated back contact cell, which comprises the following steps:

[0008] S01: According to the TBC standard process, through the graphics processing in the P and N regions of the silicon wafer to complete the preparation of surface passivation precursor;

[0009] S02: The silicon wafer is fixed on the silk-screen printing table, and the back of the silicon wafer is metallized by silk-screen printing; during the process, only the fine grid is printed, and the fine grid extends beyond the range of the cell sample;

[0010] S03: After printing, the table is heated quickly, and the fine grid is dried as a reserved end for welding, which is used for edge welding during component welding;

[0011] S04: Transfer silicon wafers to plate sintering furnace after drying.

[0012] The second main purpose of the invention is to provide a silk-screen printing table suitable for the process. In the process of metallization, only the fine grid is printed, and the reserved welding area is directly attached to the silk-screen printing table, which is dried in place and separated after curing. The thermal conductive layer is used to buffer the slight fluctuations in the heat transfer process, so that the heat dispersion is more uniform and the metallization effect is improved.

[0013] The above object of the present invention is achieved by the following technical solutions:

[0014] The invention relates to a silk-screen printing table, which comprises a printing table, a control module and a control interface;

[0015] The printing table comprises a heating layer, a thermal conductive layer and a table which are arranged successively from bottom to top;

[0016] The thermal conductive layer comprises a thermal silicone layer arranged from bottom to top, a circulating water interlayer and a thermal metal layer arranged from bottom to top. And the thermal metal layer is fixed and connected with the table to ensure the uniform distribution of heat. The thermal silicone layer is fixed connected with the heating layer to provided good heat conduction effect.

[0017] The two ends of the circulating water interlayer are respectively provided with a water inlet and a water outlet, the water inlet is connected with an external input pipeline, the water outlet is connected with an external output pipeline, the water inlet and the water outlet are connected through the pipeline and are provided with a circulating pump for circulating water;

[0018] The circulating water interlayer is between the thermal silicone layer and the thermal metal layer. It consists of a closed space capable of containing water, and circulates cooling water through pipes, circulating pumps, external input pipes and external output pipes. Form a closed loop. The water inlet and water outlet are designed not only for water injection and drainage, but more importantly to maintain the circulating flow of the circulating water interlayer. The water inlet connects to an external water source or water pump, while the water outlet is responsible for discharging the water and returning it to the water inlet, forming a closed loop.

[0019] Preferred, when drying, the pressure inside the circulating water interlayer is 1.6 MPa. The purpose of the high-pressure environment is to increase the boiling point of the solution, so that the water can be added to a higher temperature without boiling. Specifically, the shell of the sandwich is made of corrosion-resistant and high-temperature materials, such as stainless steel. The material is set to stainless steel for the purpose of facilitating the preparation of the positive pressure environment to ensure its long-term stable operation. In addition, in order to improve the heat conduction efficiency, a material with good thermal conductivity can also be selected as the inner wall of the interlayer.

[0020] The self-circulation effect of circulating water interlayer is mainly achieved in the following steps:

[0021] Natural convection: When the heating layer begins to work, the thermal silicone layer transfers heat to the water in the circulating water interlayer. Due to the thermal expansion nature of water, hot water rises while cold water sinks, resulting in natural convection. This convection phenomenon helps the water to be evenly distributed in the interlayer, improving the efficiency of heat transfer.

[0022] External power: In order to enhance the circulation effect, the circulation pump forces the water to flow in the circulating water interlayer by providing a pressure difference, thereby speeding up the heat transfer rate.

[0023] The control module is connected with the heating layer and the circulating water interlayer, and is provided with a control circuit unit located inside the silk-screen printing table;

[0024] The control interface is arranged outside the silk-screen printing table, and is electrically connected with the control circuit unit.

[0025] Preferred, the side of the table away from the thermal conductive layer is provided with an electrostatic suction cup. The table are made of wear-resistant and corrosion-resistant materials to ensure good performance and appearance during prolonged use. In addition, the suction cup set on the table can ensure the accurate positioning of the passivated back contact cell during the printing process, improving the accuracy and efficiency of the printing.

[0026] Preferred, a cooler is also arranged on the connecting pipe of the water inlet and the water outlet. Formed a closed cooling circulation system. After the end of the silk-screen printing, it is necessary to cool the table. After the condensate input from the external input pipe is heated by the residual temperature of the table, it can be cooled by the cooler, and then returned to the circulating water interlayer again, which realizes the continuous cooling and reuse of the circulating water, and improves the energy utilization efficiency.

[0027] Preferred, the heating layer is a heating strip or an infrared heat radiator. It can provide heat steadily and efficiently. The heating strip generates heat through an electric current, while the infrared thermal radiator heats by radiating heat energy.

[0028] Preferred, the thickness of the thermal silicone layer is 1~5mm. The thermal silicone layer is used to buffer slight fluctuations in the heat generated by the heating layer, ensuring that the heat can be smoothly transferred to the table. Therefore, its thickness should not be too low.

[0029] Preferred, the thermal metal layer is a copper, aluminum or stainless steel, and its function is to rapidly and evenly conduct heat in the circulating water interlayer to the table. The metal material has excellent thermal conductivity, which ensures that the heat is evenly distributed on the table surface, avoiding local overheating or undercooling.

[0030] Preferred, the temperature sensor and the overheat protection module are also included. The overheat protection module is connected to the temperature sensor, which is arranged on the table, and is connected to the control module. The setting of the temperature sensor makes it possible to monitor the temperature of the table in real time, providing key data for temperature control. The control module adjusts the power of the heating layer according to the data of the temperature sensor, thus realizing the precise control of the table temperature. The addition of overheat protection module provides an important guarantee for the safe operation of the equipment. When the temperature sensor detects that the temperature of the table or thermal conductive layer exceeds the preset safety value, the overheat protection module immediately cuts off the power supply to the heating layer to prevent overheating damage or fire.

[0031] The third main purpose of the invention is to provide a control method for the silk-screen printing table for realizing the passivated back contact cell metallization process.

[0032] The invention relates to a control method of a silk-screen printing table, which comprises the following steps:

[0033] V01: Adjust the control circuit unit to keep the heating layer closed, the external input pipeline and the external output pipeline normally open, and part of the water is transported to the water inlet through the circulating pump to keep the water in the circulating water interlayer at low temperature and maintain stability;

[0034] V02: In the state of V01, the silicon wafer with passivated surface is fixed on the table surface, and the metal is metallized by silk-screen printing on the back of the silicon wafer. The P zone and N zone are printed by silver paste at one time, the cutting speed is 150~300mm / s, and the down pressure is 10~100N;

[0035] V03: After the silk-screen printing, turn on the heating switch, close the external input pipeline and the external output pipeline, adjust the internal pressure of the circulating water interlayer to 1.6MPa, and keep the water in the microcirculation state; Heat is transferred to the table through the thermal silicone layer, circulating water interlayer and thermal metal layer, and the grid line on the table is dried.

[0036] V04: After drying, sample to confirm the curing effect of the silver paste, remove the sample from the drying table and judge the curing effect of the silver paste by reserving the welding area to preserve the shape, and transfer the silicon wafer to the plate sintering furnace;

[0037] V05: Adjust the control circuit unit, turn off the heating switch, start the cooler, open the external input pipeline and the external output pipeline, control the water input from the water inlet through the circulating water interlayer and the water outlet, into the cooler to cool down, and send the cooled condensate pump to the water inlet to cool the table;

[0038] V06: When the table is lowered to the set temperature, open the external input pipeline and the external output pipeline after pressure relief, clean the table, remove residues and impurities, repeat the steps of V01~V05.

[0039] Preferred, in the V03 step, the heating power of the heating layer is adjusted by the control module to maintain the table temperature. The thermal silicone layer is used as the heat conduction medium between the heating layer and the circulating water interlayer, the heat generated by the heating layer is efficiently transferred to the circulating water interlayer. The circulating water flows in the interlayer, absorbs the heat transferred by the thermal silicone layer, and further distributes the heat to the entire thermal conductive layer through the circulation of the water. The thermal metal layer has excellent heat conduction performance, which can quickly distribute the heat in the circulating water interlayer evenly to the entire table surface to ensure the consistency of the table temperature.

[0040] Preferred, in the V04 step, the metallized silicon wafer is placed in the plate sintering furnace and sintered in the temperature range of 600~800 °C to ensure the conformal property of the welded end. On the one hand, the sintering conditions of the front side of the passivated back contact cell are improved, and the hydrogen overflow of the front side can be controlled through plate temperature control to ensure hydrogen passivation, thus improving the Uocof the cell.

[0041] Through the above technical solutions, beneficial effects of the present invention are:

[0042] (1) The invention provides a metallization process for a passivated back contact cell, in which the main gate is removed and the welding area is reserved for hole transport and electron transport area respectively; The isolation between the P region and the N region is also simplified, greatly simplifying the difficulty of metallization of the passivated back contact cell structure; The welding yield of the components is increased by 3~5%, which solves the problem of welding accuracy, and the CTM is increased by 0.3~0.7%, which reduces the KWH cost. On this basis, the shading problem of the back main grid and the welding strip is reduced, and the double-sided ratio of the cell and the corresponding components is improved. And by improving the printing table and increasing the drying function, the printed grid line can be quickly cured and formed to ensure the production capacity and effect of the cell.

[0043] (2) The invention provides a silk-screen printing table with unique structural characteristics, and the printing table integrates a heating layer, a thermal conductive layer and a table. Not only makes the temperature control in the printing process more accurate and stable, but also improves the overall heat transfer efficiency. The thermal conductive layer adopts the combination of thermal silicone layer, circulating water interlayer and thermal metal layer, which can more effectively conduct the heat generated by the heating layer evenly and quickly to the table, ensuring the temperature uniformity during the printing process, thereby improving the printing quality. By precisely controlling the water temperature and flow of the water inlet, the table temperature can be precisely adjusted. In addition, combined the temperature sensor and control module, the table temperature can be automatically monitored and adjusted to ensure that the table can maintain a stable temperature under different working conditions.

[0044] (3) The circulating water interlayer in the invention enables the temperature of the table surface to be rapidly adjusted by the flow of circulating water, making the temperature control of the table surface more flexible and efficient. When heat transfer is required, the water is kept in microcirculation to maintain a uniform temperature distribution. Avoid local overheating or cooling. Water as a heat transfer medium can transfer heat from the thermal metal layer to the table. Due to the large heat capacity of water, it can effectively absorb and store heat, so as to achieve heat transfer. In addition, by precisely controlling the power of the heating layer, the temperature of the table can be precisely adjusted. When heat conduction is not required, the connection between the inlet and the external cooling water allows the thermal metal layer to be cooled quickly after the drying, improving the efficiency of the equipment. Combined the water cooling system, the flowing water quickly takes away the heat on the table to achieve rapid cooling of the table.

[0045] (4) The control module and control interface of the invention make the operation of the whole printing table more convenient and intelligent. The control module realizes the precise control of the heating layer and circulating water interlayer through the internal control circuit unit, which can realize the rapid rise and fall of the table temperature and maintain the stability to meet the different needs of different printing materials for temperature. The control interface provides an intuitive and easy to operate table, so that the operator can easily adjust and control the parameters of the silk-screen printing table. This design not only improves the operation efficiency, but also reduces the difficulty of operation, making the silk-screen printing process simpler and more reliable.Illustration

[0046] In order to more clearly explain the technical scheme in the embodiment of the invention or the prior art, the following is a brief introduction of the drawings required to be used in the description of the embodiment or the prior art. It is obvious that the drawings in the description below are only some embodiments recorded in the invention. Other drawings can also be obtained from these drawings.

[0047] Fig. 1 is a structure schematic diagram of grid line in Example 1 of the invention;

[0048] Fig. 2 is a structural diagram of the printing table in Example 2 of the invention;

[0049] Reference number: 11. heating layer, 12. thermal silicone layer, 13. circulating water interlayer, 14. thermal metal layer, 15. table, 131. water inlet, 132. water outlet, 133. external input pipeline, 134. external output pipeline, 135. circulation pump, 136, cooler.Detailed description of preferred embodiments

[0050] The following is a clear and complete description of the technical scheme in the embodiment of the invention in combination with the drawings attached to the embodiment of the invention. Obviously, the described embodiment is only a part of the embodiment of the invention, but not the whole embodiment.

[0051] It should be noted that when a component is said to be "fixed" to another component, it may be directly on the other component or it may also exist in a central component. When a component is considered to be "connected" to another component, it may be directly connected to another component or there may also be a centered component. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the sole embodiment.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as would normally be understood by a person skilled in the technical field belonging to the present invention. The terms used in the specification of the invention are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more related listed items.

[0053] Example 1

[0054] A metallization process for a passivated back contact cell comprises the following operating steps:

[0055] S01: According to the TBC standard process, through the graphics processing in the P and N regions of the silicon wafer to complete the preparation of surface passivation precursor;

[0056] S02: As shown in Figure 1, the silicon wafer is fixed on the silk-screen printing table, and the back of the silicon wafer is metallized by silk-screen printing. In the process, only the fine grid is printed, and the fine grid extends beyond the range of the cell sample;

[0057] S03: After printing, the table is heated quickly, and the fine grid is dried as a reserved end for welding, which is used for edge welding during component welding;

[0058] S04: Transfer silicon wafers to plate sintering furnace after drying.

[0059] In proportion:

[0060] It is necessary to complete the fine grid printing in the P zone and the N zone respectively, form a gear shaper or additional printed insulation adhesive for isolation, and then print the corresponding main grid in the P zone and the N zone by grasping points, and contact the welding pad with the design solder spot of the main grid to finally complete the preparation of TBC components.

[0061] After detection, the invention provides a metallization process of passivated back contact cell, by removing the main gate, the welding area is reserved for hole transmission and electron transmission area respectively; The isolation between the P region and the N region is also simplified, greatly simplifying the difficulty of metallization of the passivated back contact cell structure; The component welding yield is increased by 4%, which solves the problem of welding accuracy, and the CTM is increased by 0.5%, reducing the KWH cost. On this basis, the shading problem of the back main grid and the welding strip is reduced, and the double-sided ratio of the cell and the corresponding components is improved. And by improving the printing table and increasing the drying function, the printed grid line can be quickly cured and formed to ensure the production capacity and effect of the cell.

[0062] Example 2

[0063] The silk-screen printing table shown in Fig. 1 comprises a printing table, a control module and a control interface;

[0064] The printing table comprises a heating layer 11, a thermal conductive layer and a table 15, which are arranged successively from bottom to top;

[0065] The thermal conductive layer comprises a thermal silicone layer 12, a circulating water interlayer 13 and a thermal metal layer 14 arranged from bottom to top. And the thermal metal layer 14 is fixed and connected with the table 15 to ensure uniform heat distribution; The thermal silicone layer 12 is fixed connected with the heating layer 11; Provide good heat conduction effect.

[0066] The two ends of the circulating water interlayer 13 are respectively provided with water inlet 131 and water outlet 132. The water inlet 131 is connected with an external input pipeline 133, and the water outlet 132 is connected with an external output pipeline 134. The water inlet 131 and the water outlet 132 are connected through a pipeline and provided with a circulating pump 135 for circulating water.

[0067] The circulating water interlayer 13 is between the thermal silicone layer 12 and the thermal metal layer 14. It consists of a closed space capable of containing water, and circulates the cooling water through pipes, circulating pump 135, external input pipeline 133 and external output pipeline 134. Form a closed loop. The water inlet 131 and water outlet 132 are designed not only for water injection and drainage, but more importantly to maintain the circulating flow of the circulating water interlayer. The water inlet 131 is connected to an external water source or pump, while the water outlet 132 is responsible for discharging the water and returning it to the water inlet 131, forming a closed loop.

[0068] The silk-screen printing table provided by the invention integrates a heating layer 11, a thermal conductive layer and a table 15. Not only makes the temperature control in the printing process more accurate and stable, but also improves the overall heat transfer efficiency. The thermal conductive layer adopts the combination of thermal silicone layer 12, circulating water interlayer 13 and thermal metal layer 14, which can more effectively conduct the heat generated by the heating layer 11 evenly and quickly to the table 15, ensuring the temperature uniformity during the printing process, thereby improving the printing quality. By precisely controlling the water temperature and flow of the water inlet 131, the temperature of the table 15 can be precisely adjusted. In addition, combined with the temperature sensor and control module, the temperature of the table 15 can be automatically monitored and adjusted to ensure that the table 15 can maintain a stable temperature under different working conditions.

[0069] Specific, laminated enclosures are made of corrosion-resistant, heat-resistant materials to ensure long-term stable operation. In addition, in order to improve the heat conduction efficiency, a material with good thermal conductivity can also be selected as the inner wall of the interlayer.

[0070] In the invention, the circulating water interlayer 13 is arranged so that the temperature of the table 15 can be quickly adjusted by the flow of circulating water, so that the temperature control of the table 15 is more flexible and efficient. When heat transfer is required, the water is kept in microcirculation to maintain a uniform temperature distribution. Avoid local overheating or cooling. At this time, water acts as a medium for heat transfer, which can transfer heat from the thermal metal layer 14 to the table 15. Due to the large heat capacity of water, it can effectively absorb and store heat, so as to achieve heat transfer. In addition, the power of the heating layer 11 is precisely controlled, the temperature of the table 15 can be precisely adjusted. When no heat transfer is required, the connection between the water inlet 131 and the external cooling water allows the thermal metal layer 14 to be cooled quickly after drying, improving the efficiency of the equipment. Combined with the water cooling system, the flowing water quickly takes away the heat on the table 15 to achieve rapid cooling of the table 15.

[0071] Preferred, the side of the table 15 away from the thermal conductive layer is provided with an electrostatic suction cup. Table 15 is made of wear-resistant and corrosion-resistant materials to ensure good performance and appearance during prolonged of use. In addition, the suction cup set on the table 15 can ensure the accurate positioning of the passivated back contact cell during the printing process, improving the accuracy and efficiency of the printing.

[0072] Preferred, a cooler 136 is also provided on the connecting pipe of the water inlet 131 and the water outlet 132. Formed a closed cooling circulation system. After the end of the screen printing, it is necessary to cool the table 15, and the condensed water entered by the external input pipe 133 can be cooled by the cooler 136 after heating the residual temperature of the table 15, and then return to the circulating water interlayer 13 again to achieve continuous cooling and reuse of the circulating water, and improve the energy utilization efficiency.

[0073] Preferred, the heating layer 11 is a heating strip or infrared heat radiator. It can provide heat steadily and efficiently. The heating strip generates heat through an electric current, while the infrared thermal radiator heats by radiating heat energy.

[0074] Preferred, the thickness of the thermal silicone layer 12 is 1~5mm. The thermally silicone layer 12 is used to buffer slight fluctuations in the heat generated by the heating layer 11, ensuring that the heat is smoothly transferred to the table 15. Therefore, its thickness should not be too low.

[0075] Preferred, the thermal conducting metal layer 14 is made of copper, aluminum or stainless steel and its function is to rapidly and evenly conduct heat from the circulating water interlayer 13 to the table 15. The metal material has excellent thermal conductivity, which ensures that the heat is evenly distributed on the table 15, avoiding local overheating or undercooling.

[0076] Preferred, the temperature sensor and the overheat protection module are also included. The overheat protection module is connected to the temperature sensor, which is arranged on the table 15, and is connected to the control module. The setting of the temperature sensor makes it possible to monitor the temperature of the table 15 in real time, providing key data for temperature control. The control module adjusts the power of the heating layer 11 according to the data of the temperature sensor, thus realizing the precise control of the temperature of the table 15. The addition of overheat protection module provides an important guarantee for the safe operation of the equipment. When the temperature sensor detects that the temperature of the table 15 or the thermal conductive layer exceeds the preset safety value, the overheat protection module immediately cuts off the power supply to the heating layer 11 to prevent overheating damage or fire.

[0077] Example 3

[0078] The invention relates to a control method of a silk-screen printing table, which comprises the following steps:

[0079] V01: Adjust the control circuit unit to keep the heating layer closed, the external input pipeline and the external output pipeline normally open, and part of the water is transported to the water inlet through the circulating pump to keep the water in the circulating water interlayer at low temperature and maintain stability;

[0080] V02: In the state of V01, the silicon wafer with passivated surface is fixed on the table surface, and the metal is metallized by silk-screen printing on the back of the silicon wafer. The P zone and N zone are printed by silver paste at one time, the cutting speed is 150~300mm / s, and the down pressure is 10~100N;

[0081] V03: After the silk-screen printing, turn on the heating switch, close the external input pipeline and the external output pipeline, adjust the internal pressure of the circulating water interlayer to 1.6MPa, and keep the water in the microcirculation state; Heat is transferred to the table through the thermal silicone layer, circulating water interlayer and thermal metal layer, and the grid line on the table is dried.

[0082] V04: After drying, sample to confirm the curing effect of the silver paste, remove the sample from the drying table and judge the curing effect of the silver paste by reserving the welding area to preserve the shape, and transfer the silicon wafer to the plate sintering furnace;

[0083] V05: Adjust the control circuit unit, turn off the heating switch, start the cooler, open the external input pipeline and the external output pipeline, control the water input from the water inlet through the circulating water interlayer and the water outlet, into the cooler to cool down, and send the cooled condensate pump to the water inlet to cool the table;

[0084] V06: When the table is lowered to the set temperature, open the external input pipeline and the external output pipeline after pressure relief, clean the table, remove residues and impurities, repeat the steps of V01~V05.

[0085] Preferred, in the V03 step, the heating power of the heating layer is adjusted by the control module to maintain the table temperature. The thermal silicone layer is used as the heat conduction medium between the heating layer and the circulating water interlayer, the heat generated by the heating layer is efficiently transferred to the circulating water interlayer. The circulating water flows in the interlayer, absorbs the heat transferred by the thermal silicone layer, and further distributes the heat to the entire thermal conductive layer through the circulation of the water. The thermal metal layer has excellent heat conduction performance, which can quickly distribute the heat in the circulating water interlayer evenly to the entire table surface to ensure the consistency of the table temperature.

[0086] Preferred, in the V04 step, the metallized silicon wafer is placed in the plate sintering furnace and sintered in the temperature range of 600~800 °C to ensure the conformal property of the welded end. On the one hand, the sintering conditions of the front side of the passivated back contact cell are improved, and the hydrogen overflow of the front side can be controlled through plate temperature control to ensure hydrogen passivation, thus improving the Uocof the cell.

[0087] The technical personnel of the trade should understand that the invention is not limited by the above embodiments, the above embodiments and the description only describe the principle of the invention, without deviating from the spirit and scope of the invention, the invention is subject to various changes and improvements, and these changes and improvements fall within the scope of the invention that requires protection. The scope of protection claimed by the invention is defined by the attached claims and their equivalents.

Claims

1. A silk-screen printing table, which is applied to the metallization process of passivated back contact cell，characterized in that, the metallization process for a passivated back contact cell, which comprises the following steps:S01: the graphics processing in the P and N regions of the silicon wafer to complete the preparation of surface passivation precursor;S02: The silicon wafer is fixed on the silk-screen printing table, and the back of the silicon wafer is metallized by silk-screen printing; during the process, only the fine grid is printed, and the fine grid extends beyond the range of the cell sample;S03: After printing, the table is heated quickly, and the fine grid is dried as a reserved end for welding, which is used for edge welding during component welding;S04: Transfer silicon wafers to plate sintering furnace after drying;the silk-screen printing table, which comprises a printing table, a control module and a control interface;The printing table comprises a heating layer, a thermal conductive layer and a table which are arranged successively from bottom to top;The thermal conductive layer comprises a thermal silicone layer arranged from bottom to top, a circulating water interlayer and a thermal metal layer arranged from bottom to top. And the thermal metal layer is fixed and connected with the table. The thermal silicone layer is fixed connected with the heating layer;The two ends of the circulating water interlayer are respectively provided with a water inlet and a water outlet, the water inlet is connected with an external input pipeline, the water outlet is connected with an external output pipeline, the water inlet and the water outlet are connected through the pipeline and are provided with a circulating pump for circulating water;The control module is connected with the heating layer and the circulating water interlayer, and is provided with a control circuit unit located inside the silk-screen printing table;The control interface is arranged outside the silk-screen printing table, and is electrically connected with the control circuit unit.

2. The silk-screen printing table according to claim 1, characterized in that, the side of the table away from the thermal conductive layer is provided with an electrostatic suction cup.

3. The silk-screen printing table according to claim 1, characterized in that, a cooler is also arranged on the connecting pipe of the water inlet and the water outlet.

4. The silk-screen printing table according to claim 1, characterized in that, the heating layer is a heating strip or an infrared heat radiator.

5. The silk-screen printing table according to claim 1, characterized in that, when drying, the pressure inside the circulating water interlayer is 1.6 MPa.

6. The silk-screen printing table according to claim 1, characterized in that, the temperature sensor and the overheat protection module are also included. The overheat protection module is connected to the temperature sensor, which is arranged on the table, and is connected to the control module.

7. The control method of a silk-screen printing table according to claim 1, characterized in that, which comprises the following steps:V01: Adjust the control circuit unit to keep the heating layer closed, the external input pipeline and the external output pipeline normally open, and part of the water is transported to the water inlet through the circulating pump to keep the water in the circulating water interlayer at low temperature and maintain stability;V02: In the state of V01, the silicon wafer with passivated surface is fixed on the table surface, and the metal is metallized by silk-screen printing on the back of the silicon wafer. The P zone and N zone are printed by silver paste at one time;V03: After the silk-screen printing, turn on the heating switch, close the external input pipeline and the external output pipeline, adjust the internal pressure of the circulating water interlayer to 1.6MPa, and keep the water in the microcirculation state; Heat is transferred to the table through the thermal silicone layer, circulating water interlayer and thermal metal layer, and the grid line on the table is dried;V04: After drying, transfer the silicon wafer to the plate sintering furnace;V05: Adjust the control circuit unit, turn off the heating switch, start the cooler, open the external input pipeline and the external output pipeline, control the water input from the water inlet through the circulating water interlayer and the water outlet, into the cooler to cool down, and send the cooled condensate pump to the water inlet to cool the table;V06: When the table is lowered to the set temperature, open the external input pipeline and the external output pipeline after pressure relief, clean the table, remove residues and impurities, repeat the steps of V01~V05.

8. The control method of a silk-screen printing table according to claim 7, characterized in that, in the V03 step, the heating power of the heating layer is adjusted by the control module to maintain the table temperature.

9. The control method of a silk-screen printing table according to claim 7, characterized in that, in the V04 step, the metallized silicon wafer is placed in the plate sintering furnace and sintered in the temperature range of 600~800 °C to ensure the conformal property of the welded end.

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