阅读说明：本技术 一种降低晶硅太阳能电池el绕镀脏污的pecvd工艺 (PECVD process for reducing EL (electro-deposition) plating contamination of crystalline silicon solar cell ) 是由 段少雷 彭平 陈庆发 郭飞 陈磊 夏中高 李旭杰 于 2021-09-10 设计创作，主要内容包括：本发明公开了一种降低晶硅太阳能电池EL绕镀脏污的PECVD工艺,涉及硅太阳能电池制造领域,包括S1：装片、进舟；S2：一次升温通气；S3：抽真空；S4：检漏；S5：二次恒温通气；S6：恒压通气；S7：多层工艺沉积；S8：抽真空；S9：回压；S10：出舟；S11：卸载硅片,利用自动化将工艺后的硅片从石墨舟内取出,插入花篮中,转交到下一个工序,本发明通过在PECVD工艺过程中减少污染源及提高氮化硅的钝化效果来抵消氧化铝绕镀引起的EL脏污问题。(The invention discloses a PECVD (plasma enhanced chemical vapor deposition) process for reducing EL (electro-luminescent) plating contamination of a crystalline silicon solar cell, which relates to the field of silicon solar cell manufacturing and comprises the following steps of S1: loading and feeding the wafers into a boat; s2: heating and ventilating for the first time; s3: vacuumizing; s4: leak detection is carried out; s5: secondary constant temperature ventilation; s6: ventilating at constant pressure; s7: depositing by a multilayer process; s8: vacuumizing; s9: back pressure; s10: taking out of the boat; s11: unloading the silicon wafer, taking out the processed silicon wafer from the graphite boat by automation, inserting the silicon wafer into a flower basket, and transferring the silicon wafer to the next procedure.)

1. A PECVD process for reducing EL (electro-luminescent) plating contamination of a crystalline silicon solar cell is characterized by comprising the following steps of:

s1: loading and feeding the silicon wafers, namely loading the silicon wafers subjected to back coating into a graphite boat in a positive coating process by using automatic equipment, then opening a furnace door, automatically conveying the graphite boat filled with the silicon wafers to be processed into a process furnace pipe, and closing the furnace door;

s2: firstly, automatically heating the process furnace tube to a process setting temperature of 480-;

s3: vacuumizing, wherein the process furnace tube treated in the step S2 is vacuumized to reach the vacuum condition required by the film deposition reaction, the set temperature is 480-;

s4: detecting leakage, wherein the reaction needs to be finished under a vacuum condition, the tightness of the reaction cavity is detected, the leakage rate required by the process is met, and air is prevented from entering;

s5: introducing 5000-10000sccm ammonia gas into the process furnace tube treated in the step S4 at constant temperature for the second time, balancing the temperature in the cavity, slowly decomposing hydrogen gas to be adsorbed on the surface of the silicon wafer, forming ion groups containing more H & lt + & gt in the subsequent discharge process, improving the passivation effect of the surface of the silicon wafer, reducing the occurrence of plating-around contamination, setting the temperature at 480-530 ℃ and the time duration of the step at 100-200S;

s6: introducing certain amount of process gases of silane and ammonia gas into the reaction chamber of the process furnace tube treated in the step S5 in advance before the film is deposited, so that the furnace tube reaches the pressure atmosphere required by the process in advance, wherein the constant pressure condition is set to be at 480-530 ℃;

s7: performing multi-layer process deposition, namely introducing process gases of silane and ammonia for the first time, setting the on-off time proportion of a radio frequency power supply to discharge, and depositing a first layer of silicon nitride film on the surface of a silicon wafer; then introducing process gases of silane and ammonia gas for the second time, setting the on-off time proportion of a radio frequency power supply to discharge, and depositing and generating a second layer of silicon nitride film on the surface of the silicon wafer; finally, introducing process gases of silane and ammonia for the third time, setting the on-off time proportion of a radio frequency power supply to discharge, and depositing on the surface of the silicon wafer to generate a third layer of silicon nitride film;

s8: vacuumizing, after the deposition of the multilayer process is finished, pumping unreacted gas and some products out of the cavity through a vacuum pump, ensuring that no silane or ammonia gas remains in the cavity, and setting the vacuumizing condition as follows: the temperature is 480 ℃ and 530 ℃, and the step time is 40-60 s;

s9: and (3) back pressure, namely filling nitrogen into the reaction cavity, so that the pressure returns to normal pressure to prepare for opening the furnace door, wherein the back pressure condition is as follows: the temperature is 480-530 ℃, the nitrogen flow is 10000-30000sccm, and the step duration is 50-80 s;

s10: discharging, namely opening a furnace door, automatically conveying the graphite boat filled with the processed silicon wafers out of the furnace tube, closing the furnace door, wherein the discharging speed is 3500cm/min, and the step time is 80-100 s;

s11: and unloading the silicon wafer, taking out the processed silicon wafer from the graphite boat by automation, inserting the silicon wafer into the flower basket, and transferring to the next procedure.

2. The PECVD process for reducing EL wrap-around contamination of a crystalline silicon solar cell as recited in claim 1, wherein the boat speed is set to 3500cm/min in step S1, and the step time is 80-100S.

3. The PECVD process for reducing EL wrap-around contamination of a crystalline silicon solar cell as recited in claim 1, wherein the parameters of the first process deposition are set as follows: the temperature is set at 480-530 ℃, the silane flow is 1500-2000sccm, the ammonia gas flow is 6000-10000sccm, the power of the RF power source is 15-18Kw, the on-time of the RF power source is 4-8ms, the off-time is 50-100ms, and the step duration is 200-300 s.

4. The PECVD process for reducing EL wrap-around contamination of a crystalline silicon solar cell as recited in claim 1, wherein the parameters of the second deposition process are set as follows: the temperature is set at 480-530 ℃, the silane flow is 1000-1500sccm, the ammonia flow is 9000-13000sccm, the RF power is 17-20Kw, the RF power is turned on for 4-8ms, the turn-off time is 50-100ms, and the step duration is 100-200 s.

5. The PECVD process for reducing EL wrap-around contamination of a crystalline silicon solar cell as recited in claim 1, wherein the deposition parameters of the third process are set as follows: the temperature is set at 480-530 ℃, the silane flow is 700-1200sccm, the ammonia flow is 9000-13000sccm, the RF power is 17-20Kw, the RF power is turned on for 4-8ms, the turn-off time is 50-100ms, and the step duration is 450-550 s.

6. The PECVD process for reducing EL wraparound plating contamination of the crystalline silicon solar cell as claimed in claim 1, wherein during the step S4, the temperature is set at 480-.

7. The PECVD process of claim 1, wherein during step S5, the furnace mouth temperature is 530 ℃, the furnace tail temperature is 480 ℃, the ammonia gas flow is 6000sccm, and the time of step S5 is 100-.

8. The PECVD process for reducing the EL bypass plating contamination of the crystalline silicon solar cell as recited in claim 1, wherein the flow rate of silane is 1500-2000sccm, the flow rate of ammonia is 6000-10000sccm and the duration of step S6 is 10-30S in the step S6.

Technical Field

The invention relates to the field of silicon solar cell manufacturing, and mainly relates to a PECVD (plasma enhanced chemical vapor deposition) process capable of reducing EL (electro-luminescent) plating contamination.

Background

At present, the manufacturing processes of the crystalline silicon solar PERC battery mainly comprise texturing, diffusion, SE, etching, annealing, back passivation, PECVD, screen printing and sintering, wherein the back passivation dielectric film alumina is mostly finished by adopting an ALD (atomic layer deposition) process. The ALD process is completed through a water process, in order to improve efficiency and yield and reduce power attenuation of components, an ozone process is used for replacing the water process to generate single-sided alumina to complete a back passivation process, and the single-sided alumina has the defects that front-side plating is generated, EL is easy to generate plating-around dirt after front-side PECVD and printing sintering, and the yield of a production line is influenced. The proportion of the dirt is reduced, the overall yield of the production line can be improved, and the overall competitiveness of the products of the enterprise in the industry is improved.

The invention is carried out by taking the manufacturing process flow of the selective emitter back passivation high-efficiency battery as the technical background, and researches the front PECVD process in the manufacturing process. The PECVD process uses low-temperature plasma as an energy source, a sample is placed under low pressure, the temperature of the sample is raised to a preset temperature by glow discharge (or a heating element is additionally arranged), then a proper amount of reaction gas (silane and ammonia gas) is introduced, the gas is subjected to a series of chemical reactions and plasma reactions, a solid film (silicon nitride) is formed on the surface of the sample, the film can repair lattice defects on the surface of a silicon wafer to fill dangling bonds, the silicon wafer surface has a good passivation effect, poor EL defects are improved, and the yield of a production line is improved.

Investigation shows that most of battery manufacturers solve the problem of ALD single-side aluminum oxide plating by adjusting the ALD process (the plating problem is unavoidable, the final effect is not obvious), the process of the front PECVD process is not optimized, and the problem of EL contamination caused by aluminum oxide plating is offset by reducing a pollution source and improving the passivation effect of silicon nitride in the PECVD process.

Disclosure of Invention

The invention aims to solve the problem of pollution of EL round plating in the conventional front-side PECVD process, provides the PECVD process for reducing the pollution of the EL round plating of the crystalline silicon solar cell, and has an obvious effect of improving the pollution of the EL round plating.

In order to achieve the purpose, the invention adopts the following technical scheme:

a PECVD process for reducing EL (electro-luminescent) plating contamination of a crystalline silicon solar cell comprises the following steps:

s1: loading and feeding the silicon wafers, namely loading the silicon wafers subjected to back coating into a graphite boat in a positive coating process by using automatic equipment, then opening a furnace door, automatically conveying the graphite boat filled with the silicon wafers to be processed into a process furnace pipe, and closing the furnace door;

s2: firstly, automatically heating the process furnace tube to a process setting temperature of 480-;

s3: vacuumizing, wherein the process furnace tube treated in the step S2 is vacuumized to reach the vacuum condition required by the film deposition reaction, the set temperature is 480-;

s4: detecting leakage, wherein the reaction needs to be finished under a vacuum condition, the tightness of the reaction cavity is detected, the leakage rate required by the process is met, and air is prevented from entering;

s5: introducing 5000-10000sccm ammonia gas into the process furnace tube treated in the step S4 at constant temperature for the second time, balancing the temperature in the cavity, slowly decomposing hydrogen gas, adsorbing the hydrogen gas on the surface of the silicon wafer, forming ion groups containing more H & lt + & gt in the subsequent discharge process, improving the passivation effect of the surface of the silicon wafer, and reducing the occurrence of plating-around contamination; setting the temperature at 480-;

s6: introducing certain amount of process gases of silane and ammonia gas into the reaction chamber of the process furnace tube treated in the step S5 in advance before the film is deposited, so that the furnace tube reaches the pressure atmosphere required by the process in advance, wherein the constant pressure condition is set to be at 480-530 ℃;

s7: performing multi-layer process deposition, namely introducing process gases of silane and ammonia for the first time, setting the on-off time proportion of a radio frequency power supply to discharge, and depositing a first layer of silicon nitride film on the surface of a silicon wafer; then introducing process gases of silane and ammonia gas for the second time, setting the on-off time proportion of a radio frequency power supply to discharge, and depositing and generating a second layer of silicon nitride film on the surface of the silicon wafer; finally, introducing process gases of silane and ammonia for the third time, setting the on-off time proportion of a radio frequency power supply to discharge, and depositing on the surface of the silicon wafer to generate a third layer of silicon nitride film;

s8: vacuumizing, after the deposition of the multilayer process is finished, pumping unreacted gas and some products out of the cavity through a vacuum pump, ensuring that no silane or ammonia gas remains in the cavity, and setting the vacuumizing condition as follows: the temperature is 480 ℃ and 530 ℃, and the step time is 40-60 s;

s9: and (3) back pressure, namely filling nitrogen into the reaction cavity, so that the pressure returns to normal pressure to prepare for opening the furnace door, wherein the back pressure condition is as follows: the temperature is 480-530 ℃, the nitrogen flow is 10000-30000sccm, and the step duration is 50-80 s;

s10: discharging, namely opening a furnace door, automatically conveying the graphite boat filled with the processed silicon wafers out of the furnace tube, closing the furnace door, wherein the discharging speed is 3500cm/min, and the step time is 80-100 s;

s11: the silicon wafer manufactured in S8 was taken out of the graphite boat by automation, inserted into a basket, and transferred to the next step.

Preferably, the boat feeding speed in the step S1 is set to 3500cm/min, and the time length of the step S1 is 80-100S.

Preferably, the parameters of the first process deposition are set as follows: the temperature is set at 480-530 ℃, the silane flow is 1500-2000sccm, the ammonia gas flow is 6000-10000sccm, the power of the RF power source is 15-18Kw, the on-time of the RF power source is 4-8ms, the off-time is 50-100ms, and the step duration is 200-300 s.

Preferably, the parameters of the second process deposition are set as follows: the temperature is set at 480-530 ℃, the silane flow is 1000-1500sccm, the ammonia flow is 9000-13000sccm, the RF power is 17-20Kw, the RF power is turned on for 4-8ms, the turn-off time is 50-100ms, and the step duration is 100-200 s.

Preferably, the parameters of the third process deposition are set as follows: the temperature is set at 480-530 ℃, the silane flow is 700-1200sccm, the ammonia flow is 9000-13000sccm, the RF power is 17-20Kw, the RF power is turned on for 4-8ms, the turn-off time is 50-100ms, and the step duration is 450-550 s.

Preferably, in the process of the step S4, the setting temperature is 480-530 ℃, and the time of the step S4 is 10-30S.

Preferably, in the step S5, the furnace mouth temperature is 530 ℃, the furnace tail temperature is 480 ℃, the ammonia gas flow is 6000sccm, and the time of the step S5 is 150S.

Preferably, the flow rate of silane is 1500-.

The invention has the beneficial effects that: the PECVD process for reducing the pollution of the EL winding plating of the crystalline silicon solar cell, disclosed by the invention, does not need equipment investment, only needs to modify the original process to a certain extent, increases nitrogen purging in a constant temperature step, reduces the process temperature, simultaneously improves the refractive index and the thickness of a bottom layer film, and eliminates the reverse effect generated by the ALD single-sided alumina winding plating from the aspects of improving the passivation effect and reducing pollution, thereby reducing the pollution of the EL winding plating.

Drawings

For ease of illustration, the invention is described in detail by the following detailed description and the accompanying drawings.

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 is a finished product made by an old process;

FIG. 3 is a finished product made by the process;

Detailed Description

The above description is only an embodiment of the present invention, but the technical features of the present invention are not limited thereto, and any changes or modifications within the technical field of the present invention by those skilled in the art are covered by the claims of the present invention.

The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1:

a PECVD process for reducing EL (electro-luminescent) plating contamination of a crystalline silicon solar cell comprises the following steps:

step 1: loading the silicon wafer with the back coated film into a graphite boat in a front coating process automatically;

step 2: and (4) opening the furnace door by feeding the boat, automatically conveying the graphite boat filled with the silicon wafers to be processed into the process furnace pipe, and closing the furnace door. The boat feeding speed is 3500cm/min, and the step time is 80 s.

And step 3: the constant temperature furnace tube is provided with a heating temperature control system, and can automatically heat up to the process setting temperature: the furnace mouth is 530 ℃, the furnace tail is 480 ℃, the reaction is required to be carried out under the condition of constant temperature, the time is 400s, and the temperature in the reaction cavity is enabled to reach and be constant at the set temperature: the furnace mouth is 530 ℃, the furnace tail is 480 ℃, nitrogen of 5000sccm is introduced at the same time, air and moisture in the cavity are taken away, and the silicon wafer is prevented from being polluted by the air or the moisture, so that the occurrence of plating-around contamination is avoided.

And 4, step 4: vacuumizing the vacuumizing furnace tube to reach the vacuum condition required by the film deposition reaction, and setting the temperature: the furnace mouth is 530 ℃, the furnace tail is 480 ℃, and the step time is 240 s.

And 5: the leak detection reaction needs to be completed under a vacuum condition, the tightness of the reaction cavity is detected, the leak rate required by the process is met, and air is prevented from entering. Setting the temperature: the furnace mouth is 530 ℃, the furnace tail is 480 ℃, and the step time is 30 s.

Step 6: 6000sccm ammonia gas is introduced at constant temperature, hydrogen is slowly decomposed while the temperature in the cavity is balanced, the hydrogen is adsorbed on the surface of the silicon wafer, and ion clusters containing more H & lt + & gt are formed in the subsequent discharging process, so that the passivation effect of the surface of the silicon wafer is improved, and the occurrence of plating-around contamination is reduced. Setting the temperature: the furnace mouth is 530 ℃, the furnace tail is 480 ℃, and the step time is 150 s.

And 7: before the film is deposited at constant pressure, a certain amount of process gases, namely silane and ammonia gas, are introduced in advance, so that the furnace tube reaches the pressure atmosphere required by the process in advance, and the phenomenon of high-frequency abnormity caused by discharge current fluctuation due to sudden introduction of gas in the process step is prevented. Setting the temperature: the furnace mouth is 530 ℃, the furnace tail is 480 ℃, the silane flow is 1850sccm, the ammonia gas flow is 8400sccm, and the step duration is 30 s.

And 8: and (3) introducing process gases of silane and ammonia gas into the process deposition 1, setting the on-off time proportion of a radio frequency power supply to discharge, and depositing and generating a first layer of silicon nitride film on the surface of the silicon wafer. Setting the temperature: the furnace mouth is 530 ℃, the furnace tail is 480 ℃, the silane flow is 1850sccm, the ammonia gas flow is 8400sccm, the radio frequency power supply power is 16.5Kw, the radio frequency power supply is opened for 5ms, the radio frequency power supply is closed for 85ms, and the step duration is 300 s.

And step 9: and (3) introducing process gases of silane and ammonia gas into the process deposition 2, setting the on-off time proportion of the radio frequency power supply to discharge, and depositing and generating a second layer of silicon nitride film on the surface of the silicon wafer. Setting the temperature: the furnace mouth is 530 ℃, the furnace tail is 480 ℃, the silane flow is 1200sccm, the ammonia gas flow is 12000sccm, the power of the radio frequency power supply is 18Kw, the opening time of the radio frequency power supply is 5ms, the closing time is 55ms, and the step duration is 150 s.

Step 10: and (3) introducing process gases of silane and ammonia gas into the process deposition chamber, setting the on-off time proportion of a radio frequency power supply to discharge, and depositing a third layer of silicon nitride film on the surface of the silicon wafer. Setting the temperature: the furnace mouth is 530 ℃, the furnace tail is 480 ℃, the silane flow is 1000sccm, the ammonia gas flow is 12000sccm, the radio frequency power supply power is 18Kw, the radio frequency power supply opening time is 5ms, the closing time is 55ms, and the step duration is 480 s.

Step 11: after the vacuumizing reaction is finished, unreacted gas and some products are pumped out of the cavity through a vacuum pump, and no silane or ammonia gas is remained in the cavity. Setting the temperature: the furnace mouth is 530 ℃, the furnace tail is 480 ℃, and the step time is 50 s.

Step 12: and nitrogen is filled into the back pressure cavity, so that the pressure is returned to normal pressure, and the preparation is made for opening the furnace door. Setting the temperature: furnace mouth 530 ℃, furnace tail 480 ℃, nitrogen flow: 20000sccm, step length 50 s.

Step 13: and (4) discharging the graphite boat, opening the furnace door, automatically conveying the graphite boat filled with the silicon wafers after the process is finished out of the furnace tube, and closing the furnace door. The boat-out speed is 3500cm/min, and the step time is 80 s.

Step 14: unloading the silicon wafer, taking out the processed silicon wafer from the graphite boat by automation, inserting the silicon wafer into a flower basket, and transferring to the next procedure.

Example 2: a PECVD process for reducing EL (electro-luminescent) plating contamination of a crystalline silicon solar cell comprises the following steps:

step 1: loading the silicon wafer with the back coated film into a graphite boat in a front coating process automatically;

step 2: and (4) opening the furnace door by feeding the boat, automatically conveying the graphite boat filled with the silicon wafers to be processed into the process furnace pipe, and closing the furnace door. The boat feeding speed is 3500cm/min, and the step time is 80 s.

And step 3: the isothermal reaction needs to be carried out under the condition of constant temperature for 350s, so that the temperature in the reaction cavity is constant at the set temperature: the furnace mouth is 560 ℃ and the furnace tail is 500 ℃.

And 4, step 4: the vacuumizing furnace tube is vacuumized to reach the vacuum condition required by the film deposition reaction, and meanwhile, the furnace tube is provided with a heating temperature control system and can automatically rise to the process setting temperature: the furnace mouth is 560 ℃, the furnace tail is 500 ℃, and the step time is 300 s.

And 5: the leak detection reaction needs to be completed under a vacuum condition, the tightness of the reaction cavity is detected, the leak rate required by the process is met, and air is prevented from entering. Setting the temperature: the furnace mouth is 560 ℃, the furnace tail is 500 ℃, and the step time is 30 s.

Step 6: before the film is deposited at constant pressure, a certain amount of process gases, namely silane and ammonia gas, are introduced in advance, so that the furnace tube reaches the pressure atmosphere required by the process in advance, and the phenomenon of high-frequency abnormity caused by discharge current fluctuation due to sudden introduction of gas in the process step is prevented. Setting the temperature: the furnace mouth is 560 ℃, the furnace tail is 500 ℃, the silane flow is 1300sccm, the ammonia flow is 6600sccm, and the step duration is 30 s.

And 7: and (3) introducing process gases of silane and ammonia gas into the process deposition 1, setting the on-off time proportion of a radio frequency power supply to discharge, and depositing and generating a first layer of silicon nitride film on the surface of the silicon wafer. Setting the temperature: 560 ℃ of a furnace mouth, 500 ℃ of a furnace tail, 1300sccm of silane flow, 6600sccm of ammonia gas flow, 16.5Kw of radio frequency power supply power, 5ms of radio frequency power supply opening time, 85ms of radio frequency power supply closing time and 220s of step duration.

And 8: and (3) introducing process gases of silane and ammonia gas into the process deposition 2, setting the on-off time proportion of the radio frequency power supply to discharge, and depositing and generating a second layer of silicon nitride film on the surface of the silicon wafer. Setting the temperature: 560 ℃ of a furnace mouth, 500 ℃ of a furnace tail, 1200sccm of silane flow, 12000sccm of ammonia gas flow, 18Kw of radio frequency power supply power, 5ms of radio frequency power supply opening time, 55ms of radio frequency power supply closing time and 150s of step duration.

And step 9: and (3) introducing process gases of silane and ammonia gas into the process deposition chamber, setting the on-off time proportion of a radio frequency power supply to discharge, and depositing a third layer of silicon nitride film on the surface of the silicon wafer. Setting the temperature: the furnace mouth is 560 ℃, the furnace tail is 500 ℃, the silane flow is 1000sccm, the ammonia gas flow is 12000sccm, the power of the radio frequency power supply is 18Kw, the turn-on time of the radio frequency power supply is 5ms, the turn-off time is 55ms, and the step duration is 550 s.

And step 9: after the vacuumizing reaction is finished, unreacted gas and some products are pumped out of the cavity through a vacuum pump, and no silane or ammonia gas is remained in the cavity. Setting the temperature: the furnace mouth is 560 ℃, the furnace tail is 500 ℃, and the step time is 50 s.

Step 10: and nitrogen is filled into the back pressure cavity, so that the pressure is returned to normal pressure, and the preparation is made for opening the furnace door. Setting the temperature: furnace mouth 560 ℃, furnace tail 500 ℃, nitrogen flow: 20000sccm, step length 30 s.

Step 11: and (4) discharging the graphite boat, opening the furnace door, automatically conveying the graphite boat filled with the silicon wafers after the process is finished out of the furnace tube, and closing the furnace door. The boat-out speed is 3500cm/min, and the step time is 80 s.

Step 12: unloading the silicon wafer, taking out the processed silicon wafer from the graphite boat by automation, inserting the silicon wafer into a flower basket, and transferring to the next procedure.

The test experiment about the PECVD process for reducing the EL plating contamination of the crystalline silicon solar cell comprises the following steps:

subject: and (3) a silicon wafer to be subjected to the front PECVD process.

The experimental contents are as follows: 1. comparing the experimental process and the conventional process for the first boat silicon wafer after the machine maintenance and recovery, and comparing the experimental process and the conventional process for the boat-entering, clamping and clamping silicon wafer

Experimental groups: the PECVD new process for reducing the plating contamination of the winding is adopted in the embodiment 1;

control group: the conventional process of example 2 was used as a control.

Content of experiment 1:

and (3) data analysis: the process conversion efficiency (Eta) using the invention is not lower than that of the comparative group, the plating-around contamination is reduced by 29.24%, and the specific data are shown in the following table 1:

experiment content 2:

and (3) data analysis: the process conversion efficiency (Eta) of the invention is not lower than that of a comparison group, and the plating-around contamination is reduced by 27.29 percent; specific data are shown in table 2 below:

and (3) experimental popularization: according to experimental results, the efficiency of the process scheme is not lower than that of a production line process, the plating-around contamination of the experimental content 1 is reduced by 29.24%, and the plating-around contamination of the experimental content 2 is reduced by 27.29%. Therefore, the process scheme has popularization significance.