Circulating degumming method for monocrystalline silicon wafer and degumming system thereof

Abstract

The invention discloses a cyclic degumming method for monocrystalline silicon wafers and a degumming system thereof, which comprises the following steps: transferring a degummed mixed solution into a degumming wastewater tank, standing and precipitating, filtering and heating a supernatant liquid to obtain normal and transparent mixed circulating water, and recycling the mixed circulating water; and 3-7.5 kg of the degumming agent is added to be mixed with the mixed circulating water in the recovery water tank to prepare a secondary degumming solution, the secondary degumming solution is subjected to a degumming process, a small amount of the degumming agent is mixed with the mixed circulating water based on the degumming system, and the degummed mixed solution is recycled, so that the use amount of the degumming agent is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of debonding in photovoltaic slicing, and in particular to a cyclic debonding method and a debonding system for single crystal silicon wafers. Background Art

[0002] At present, degumming machines are generally divided into 6-tank degumming machines and the latest 8-tank degumming machines; the tank body technology of the 6-tank degumming machine is 1#2# tank body spraying, 3#4# tank body ultrasonic cleaning, 5#6# ultrasonic / degumming, and the tank body technology of the 8-tank degumming machine is 1#2# tank body spraying, 3#4# tank body ultrasonic cleaning, 5#6#7#8# ultrasonic / degumming; 25kg of degumming agent and 60-85℃ water should be put into each degumming tank for mixing. After degumming to about 150 knives, the water and degumming agent in the degumming machine are directly discharged for sewage treatment.

[0003] At present, in the degumming process, the low COD degumming effect cannot meet the normal production requirements, and normal degumming cannot be carried out. In addition, the silicon wafer will fall off after the glue layer is not softened, resulting in edge collapse, silicon falling, missing corners, hidden cracks, fragments and other abnormalities; the COD of the degumming agent is very high. Due to the stricter environmental protection requirements, direct discharge of the degumming agent mixed water requires a lot of cost for sewage treatment; the degumming agent and water are usually mixed by manual dumping. This is a chemical agent with certain safety hazards and a waste of manpower; the daily usage of the degumming agent is 50kg / day / unit, which increases the cost of degumming in monocrystalline silicon wafers. Summary of the invention

[0004] The object of the present invention is to provide a cyclic degumming method and a degumming system for single crystal silicon wafers. The mixed liquid after degumming is placed for settling, filtered and heated to obtain normal transparent mixed circulating water, 3kg to 7.5kg of degumming agent is added and mixed to prepare a secondary degumming liquid for the degumming process, and the mixed liquid after degumming is recycled and reused, thereby reducing the amount of degumming agent used and solving the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention adopts the following solutions:

[0006] A cyclic debonding method for single crystal silicon wafers, wherein the debonding agent added for the first time in the debonding machine is debonded by 140 to 160 single crystal silicon wafers, and the method comprises the following steps:

[0007] Step 1: Transfer the mixed liquid after degumming in the degumming tank to the degumming wastewater tank for static sedimentation;

[0008] Step 2: The upper layer of liquid in the degumming wastewater tank is filtered and heated in sequence to obtain mixed circulating water, and when the mixed circulating water is normal transparent clean water, it is transferred to a recovery water tank;

[0009] Step 3: adding a degumming agent to the recycling water tank for a second time, so that the degumming agent and the mixed circulating water are evenly mixed to obtain a secondary degumming liquid;

[0010] Step 4: Transfer the secondary degumming liquid from the degumming wastewater tank to the degumming tank for degumming process. After degumming is completed, repeat steps 1 to 4.

[0011] The technical concept of the present application is to transfer the mixed liquid after degumming to a degumming wastewater tank for static sedimentation, filter and heat the upper liquid to obtain normal transparent mixed circulating water, add 3kg to 7.5kg of degumming agent and mix it with the mixed circulating water to prepare a secondary degumming liquid for the degumming process, mix a smaller amount of degumming agent with the mixed circulating water based on the degumming system, and recycle the mixed liquid after degumming, thereby reducing the amount of degumming agent used and reducing costs and increasing efficiency.

[0012] Furthermore, the degumming wastewater tank is connected to the degumming tank by setting a recovery pipeline, and the standing time of the mixed liquid in the degumming wastewater tank is 3h to 18h.

[0013] Furthermore, the degumming wastewater tank is connected to the filter tank and the circulating heating water tank in sequence through pipelines, and a first pressure pump and a second pressure pump are arranged in the pipelines in sequence.

[0014] Furthermore, a plurality of filter bags are arranged in the filter tank, and the specification of the filter bags is 320 mesh to 800 mesh.

[0015] Furthermore, when the mixed circulating water in step three is black, the filter bag in the filter tank is replaced with a high-mesh filter bag, and filtering and heating are continued, and steps three and four are repeated.

[0016] Furthermore, in the secondary degumming liquid, the pH is 6-7, the 17.5% mass concentration aqueous solution is ≤1.5 million mg / L, and the added amount of the degumming agent is 3kg-7.5kg.

[0017] Furthermore, a circulating liquid injection pipeline connected to the degumming tank is provided at the bottom of the recovery water tank.

[0018] Furthermore, the secondary degumming liquid enters the degumming tank and is heated before the degumming process is performed.

[0019] Furthermore, the process from step 1 to step 4 is repeated at least 30 times.

[0020] A circulating degumming system for degumming single crystal silicon wafers adopts the above-mentioned circulating degumming method for single crystal silicon wafers, including a degumming machine, wherein a degumming tank is provided in the degumming machine, and the degumming tank is connected with a degumming wastewater tank, a filter tank, a circulating heating water tank, and a recovery water tank in sequence.

[0021] The beneficial effects of the present invention are as follows: the present invention is a cyclic degumming method and a degumming system for single crystal silicon wafers. The present invention is based on the combination of a degumming system and a cyclic degumming method. The mixed liquid after degumming is recovered into a degumming wastewater tank and filtered and heated after precipitation to obtain mixed circulating water and transferred to a recycling water tank. 3kg to 7.5kg of a degumming agent is added to the recycling water tank to prepare a secondary degumming liquid, thereby reducing the amount of the degumming agent and saving the degumming agent. After cyclic use, the degumming agent is reduced from the original 50kg / day / unit to 3kg to 7.5kg / day / unit, which is beneficial to reducing costs and increasing efficiency and reducing processing costs.

[0022] Through the recycling of the degumming agent, through the combination of an external recovery water tank, a circulating water heating tank, a filter tank, and a degumming wastewater tank, the recycling and reuse of the degumming agent and the mixed liquid can not only meet production needs, but also reduce the pressure of environmental sewage treatment. It can not only save manpower, but also avoid the safety hazards caused by manual dumping during preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a process flow chart of the present invention;

[0024] Figure 2 It is a schematic structural diagram of the circulating degumming system of the present invention.

[0025] Figure markings: 1- degumming tank, 2- recovery water tank, 3- filter tank, 30- filter bag, 4- circulating heating water tank, 5- degumming wastewater tank, 6- first pressure pump, 7- second pressure pump, 8- circulation injection pipeline, 9- recovery pipeline. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] Embodiment 1 of the present invention is a cyclic degumming method for monocrystalline silicon wafers, using a 6# tank degumming machine or an 8# tank degumming machine, and adding a degumming wastewater tank 5, a filter tank 3, a circulating heating water tank 4 and a recovery water tank 2 to connect the degumming tank 1 in the degumming machine through a recovery pipeline 9, so that the degumming agent added to the degumming machine for the first time is degummed for 140 to 160 times, and then the degumming agent is added to the degumming machine ... Figure 1 , specifically including the following steps:

[0029] Step 1: Transfer the mixed solution after degumming in the degumming tank 1 to the degumming wastewater tank 5 for static precipitation.

[0030] Furthermore, the degumming wastewater tank 5 is connected to the degumming tank 1 by setting a recovery pipe 9, and the standing time of the mixed liquid in the degumming wastewater tank 5 is 3h to 18h.

[0031] The mixed liquid of the single crystal silicon wafers that have been debonded 140 to 160 times in the debonding tank 1 is directly discharged from the debonding tank 1 to the debonding wastewater tank 5. At this time, the mixed liquid in the debonding wastewater tank 5 contains water, debonding agent, silicon powder, a small amount of cutting fluid, nickel, and a metal mixture of the worn cutting steel wire and other impurities. It is necessary to precipitate these impurities and use the upper liquid for secondary recovery.

[0032] Since the silica powder particles are very small, ranging from about 2 to 5μm, and the silica powder has strong adhesion and is dispersed in the water, in order to better filter out the silica powder and other impurities, the recovery water tank 2 is stagnant for more than 3 hours. Depending on the production rhythm, the time can be 3h to 18h to allow the silica powder and all other impurities to precipitate. The silica powder and impurities, as well as silica powder and silica powder, will mix and agglomerate with each other. The longer the time, the better the effect, thereby not affecting the secondary preparation of the upper liquid after precipitation and the degumming agent.

[0033] Step 2: The upper layer of liquid in the degumming wastewater tank 5 is filtered and heated in turn to obtain mixed circulating water. When the mixed circulating water is normal transparent purified water, it is transferred to the recovery water tank 2.

[0034] First, the upper layer of liquid in the degumming wastewater tank 5 is transferred to the filter tank 3 under the action of the first pressure pump 6. The filter bag 30 with a mesh size of 320 to 800 is arranged in the filter tank 3, so as to filter various impurities such as a small amount of silicon powder mixture contained in the upper layer of liquid, thereby filtering out more than 95% of the impurities.

[0035] Secondly, the filtered upper layer liquid is pumped into the circulating heating water tank 4 under the action of the second booster pump 7, and mixed circulating water is obtained after heating. Observe whether the mixed circulating water is in a normal, transparent and clean state, and choose whether to transfer it to the recycling water tank 2. When the mixed circulating water is in a normal, transparent and clean state, the mixed circulating water is transferred to the recycling water tank 2 to prepare the secondary degumming liquid. When it is in a black state, replace the filter bag 30 with a higher mesh number in the filter tank 3, so that this part of the mixed circulating water continues to filter the tank 3 and the circulating heating water tank 4, and after the mixed circulating water is normal, transparent and clean, the mixed circulating water is transferred to the recycling water tank 2.

[0036] Step three: adding a degumming agent into the recycling water tank 2, and mixing the degumming agent and the mixed circulating water evenly to obtain a secondary degumming liquid.

[0037] The amount of degumming agent used here is 6% to 15% of the amount of the first degumming agent used, that is, the amount added each time is 3kg to 7.5kg, the amount of the first degumming agent used is 50kg, and the mixed liquid after the first degumming agent is degummed is prepared to obtain the second degumming liquid, and the pH of the second degumming liquid is 6 to 7, and the 17.5% mass concentration aqueous solution is ≤1.5 million mg / L to meet the degumming requirements, thereby reducing the amount of degumming agent added in each degumming machine and reducing costs. At the same time, it is avoided that manual direct pouring into the degumming tank 1 is avoided.

[0038] Step 4: Transfer the secondary degumming liquid from the recovery water tank 2 to the degumming tank 1 for degumming process. After degumming is completed, repeat steps 1 to 4.

[0039] Furthermore, the recovery water tank 2 is connected to the filter tank 3 and the circulating heating water tank 4 in sequence through pipelines, and a first booster pump 6 and a second booster pump 7 are arranged in sequence in the pipelines. The first booster pump 6 is mainly used to transfer the upper layer of liquid in the degumming wastewater tank 5 to the filter tank 3 to filter impurities, and the second booster pump 7 is mainly used to transfer the mixed circulating water in the circulating heating water tank 4 to the recovery water tank 2. A connecting pipeline ( Figure 2 The connecting pipeline is used to transfer the mixed circulating water in the circulating heating water tank 4 to the filter tank 3 for secondary filtration.

[0040] Furthermore, when the mixed circulating water in step three is black, the filter bag 30 in the filter tank 3 is replaced with a filter bag with a high mesh number, and filtering and heating are continued, and steps three and four are repeated.

[0041] Furthermore, a circulating injection pipe 8 connected to the degumming tank 1 is provided at the bottom of the recovery water tank 2. The prepared secondary degumming liquid is injected into the degumming tank 1 by providing the circulating injection pipe 8 to degumming the next 140 to 160 single crystal silicon wafers.

[0042] Furthermore, the secondary degumming liquid enters the degumming tank 1 and is heated before the degumming process is performed.

[0043] Furthermore, the process of step 1 to step 4 is repeated at least 30 times. After at least 30 cycles per month, a new degumming agent is replaced, and steps 1 to 4 of the method are repeated, reducing the amount of degumming agent used from 50 kg / day / unit to 3-7.5 kg / day / unit, thereby reducing the cost.

[0044] Example 2

[0045] Embodiment 2 of the present invention is a circulating degumming system for degumming single crystal silicon wafers, comprising a degumming machine, wherein a degumming tank 1 is provided in the degumming machine, and the degumming tank 1 is connected to a degumming wastewater tank 5, a filter screen, a circulating heating water tank 4, and a recovery water tank 2 in sequence.

[0046] Specifically, refer to Figure 2 The degumming tank 1 is connected with the degumming wastewater tank 5 through the recovery pipe 9, the degumming wastewater tank 5 is connected with the filter tank 3 and the circulating heating water tank 4 in sequence through the pipe and the first booster pump 6 and the second booster pump 7, the circulating heating water tank 4 is connected with the recovery water tank 2 through the pipe, and the recovery water tank 2 is connected with the degumming tank 1 through the circulating injection pipe 8, so that the mixed liquid in the degumming tank 1 is recovered to the degumming wastewater tank 5 for precipitation, and then enters the recovery water tank 2 after filtration and heating, and 3kg to 7.5kg of degumming agent is added to the recovery water tank 2 to obtain the secondary degumming liquid, which is then injected into the degumming tank 1 for the next degumming process.

[0047] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A cyclic degumming method for single crystal silicon wafers, characterized in that: After the degumming agent added for the first time in the degumming machine has been degummed for 140 to 160 times, the degumming process includes the following steps: Step 1: transferring the mixed liquid after degumming in the degumming tank (1) to the degumming wastewater tank (5) for static sedimentation; Step 2: The upper layer of liquid in the degumming wastewater tank (5) is filtered and heated in sequence to obtain mixed circulating water, and when the mixed circulating water is normal transparent clean water, it is transferred to the recovery water tank (2); Step 3: adding a degumming agent into the recycling water tank (2) for a second time, and mixing the degumming agent and the mixed circulating water evenly to obtain a secondary degumming liquid; Step 4: Transfer the secondary degumming liquid from the recovery water tank (2) to the degumming tank (1) for degumming. After the degumming is completed, repeat steps 1 to 4.

2. A cyclic degumming method for single crystal silicon wafers according to claim 1, characterized in that: The degumming wastewater tank (5) is connected to the degumming tank (1) by providing a recovery pipeline (9), and the standing time of the mixed liquid in the degumming wastewater tank (5) is 3 hours to 18 hours.

3. A cyclic degumming method for single crystal silicon wafers according to claim 1, characterized in that: The degumming wastewater tank (5) is connected to the filter tank (3) and the circulating heating water tank (4) in sequence through pipelines, and a first pressure pump (6) and a second pressure pump (7) are arranged in sequence on the pipelines.

4. A cyclic debonding method for single crystal silicon wafers according to claim 3, characterized in that: A plurality of filter bags (30) are arranged in the filter tank (3), and the specification of the filter bags (30) is 320-800 meshes.

5. A cyclic debonding method for single crystal silicon wafers according to claim 3, characterized in that: When the mixed circulating water in step 3 is black, the filter bag (30) in the filter tank (3) is replaced with a filter bag with a high mesh number, and filtering and heating are continued, and steps 3 and 4 are repeated.

6. A cyclic debonding method for single crystal silicon wafers according to claim 3, characterized in that: The pH of the secondary degumming liquid is 6-7, the 17.5% mass concentration aqueous solution is ≤1.5 million mg / L, and the added amount of the degumming agent is 3kg-7.5kg.

7. A cyclic debonding method for single crystal silicon wafers according to claim 3, characterized in that: A circulating liquid injection pipeline (8) communicating with the degumming tank (1) is provided at the bottom of the recovery water tank (2).

8. A cyclic debonding method for single crystal silicon wafers according to claim 3, characterized in that: The secondary degumming liquid enters the degumming tank (1) and is heated before undergoing the degumming process.

9. A cyclic debonding method for single crystal silicon wafers according to claim 3, characterized in that: The process of step 1 to step 4 is repeated at least 30 times.

10. A circulating degumming system for degumming single crystal silicon wafers, characterized in that: A cyclic degumming method for single crystal silicon wafers according to any one of claims 1 to 9 is adopted, comprising a degumming machine, wherein a degumming tank (1) is provided in the degumming machine, and the degumming tank (1) is connected to a degumming wastewater tank (5), a filter tank (3), a circulating heating water tank (4), and a recovery water tank (2) in sequence.

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