Production system of oxalic acid solution for degreasing silicon material

Abstract

The utility model discloses an oxalic acid solution production system for degreasing a silicon material, and belongs to the technical field of oxalic acid solution production. Comprising a raw material preparation module which is composed of an oxalic acid storage tank, a surfactant adding unit and a deionized water supply device which are connected to a premixing tank through a metering pump; the multi-stage mixing module comprises a premixing tank and a main reaction kettle, a stirring paddle and an ultrasonic disperser are arranged in the premixing tank, and a double-layer stirring blade is arranged in the main reaction kettle; the filtering and purifying module comprises a filtering box, and a defoaming and spraying assembly, a filtering paper layer, a ceramic filtering plate and a stainless steel microporous filtering plate are sequentially arranged in the filtering box; and the temperature control module comprises a circulating water cooling interlayer, a temperature sensor and a PID (Proportion Integration Differentiation) controller. According to the integrated oxalic acid solution production system, efficient preparation and stability improvement of the solution are achieved through the multi-stage mixing-filtering-temperature control joint control technology, and the requirement for industrial cleaning of silicon materials is met.

Description

Technical Field

[0001] This utility model relates to a production system for oxalic acid solution for degreasing silicon materials, belonging to the field of oxalic acid solution production technology. Background Technology

[0002] Silicon materials (such as monocrystalline silicon and polycrystalline silicon) are widely used in semiconductors, photovoltaics, and precision optics, and their surface cleanliness directly affects device performance. Traditional degreasing processes often use alkaline solutions or organic solvents, but these present several problems: material corrosion risk (strong alkaline solutions, such as NaOH, readily react with silicon, causing damage to the surface microstructure and affecting subsequent processing accuracy); and poor environmental friendliness (organic solvents, such as acetone and isopropanol, are highly volatile, posing flammable and explosive risks, and incurring high wastewater treatment costs). While oxalic acid solutions have low corrosiveness to silicon and are environmentally friendly, traditional preparation equipment often results in uneven mixing, leading to crystallization or decomposition (especially under temperature fluctuations). Existing oxalic acid solution production systems for silicon material degreasing applications face the following technical bottlenecks:

[0003] 1. Low mixing efficiency and poor solution homogeneity.

[0004] Traditional oxalic acid solution production often employs single-stage stirred tanks, with mixing times exceeding 60 minutes, and the standard deviation (σ) of the solution particle size distribution is greater than 2.5 μm. Mechanical stirring has limitations: a single stirring blade (such as an anchor or paddle type) has insufficient shear rate (<200 s⁻¹), failing to effectively disperse the micelle structure of surfactants and oxalic acid, leading to localized aggregation of active ingredients; the lack of ultrasonic assistance (no integrated ultrasonic dispersion technology, frequency 20-40 kHz) makes it difficult to completely dissolve oxalic acid crystals (>10 μm), easily forming crystallization blockages in pipes or on the inner walls of the reactor.

[0005] 2. Insufficient temperature control accuracy, high oxalic acid thermal decomposition rate.

[0006] Oxalic acid solution decomposes at temperatures above 40°C, increasing its rate by three times, while traditional systems rely solely on natural heat dissipation or simple water-cooled jackets. Jacket design flaws include: the circulating water-cooled jacket uses a straight-pipe structure, resulting in a cooling water flow rate of <1.0 m / s and low heat exchange efficiency (temperature fluctuations exceeding ±3°C); and a simplistic control logic: the lack of PID temperature closed-loop control prevents real-time adjustment of cooling water flow, leading to a solution temperature runaway rate exceeding 15%.

[0007] 3. Impurities and air bubbles are not completely removed.

[0008] Existing filtration systems have insufficient capacity to retain submicron particles and foam; the filtration layers are limited: using only PP cotton or activated carbon filter cartridges, the retention rate of 0.5-1.0μm particles is less than 70%, and residual particles increase the risk of scratching the silicon wafer surface; defoaming technology is lacking.

[0009] 4. Low degree of automation

[0010] Traditional systems rely on manual parameter adjustment, resulting in poor batch stability, low metering accuracy, and affecting the consistency of solution concentration; they also lack linkage control: the mixing, filtration, and temperature control modules are not coordinated through PLC, resulting in a high frequency of manual intervention. Summary of the Invention

[0011] In order to overcome the shortcomings of the prior art, this utility model provides a production system for oxalic acid solution for degreasing silicon materials.

[0012] The technical solution adopted in this utility model is: a production system for oxalic acid solution for degreasing silicon materials, comprising:

[0013] Raw material preparation module: consists of an oxalic acid storage tank, a surfactant addition unit, and a deionized water supply device, all of which are connected to the premixing tank via a metering pump;

[0014] Multi-stage mixing module: includes a premixing tank and a main reaction vessel. The premixing tank is equipped with a stirring paddle and an ultrasonic disperser, and the main reaction vessel is equipped with double-layer stirring blades to mix the materials inside at high speed.

[0015] Filtration and purification module: includes a filter box, the outlet of the main reactor is connected to the filter box, the filter box is provided with a filter paper layer, a ceramic filter plate and a stainless steel microporous filter plate in sequence, and the top of the filter box is provided with a defoaming spray assembly;

[0016] Temperature control module: includes a circulating water-cooled jacket surrounding the main reactor and a temperature sensor installed inside it, as well as a PID controller installed on its side, which adjusts the water temperature.

[0017] Furthermore, the surfactant addition unit includes a rhamnolipin composition storage tank and a polyethylene glycol monododecyl ether storage tank, which are mixed at a weight ratio of 1:2 and then added to a premix tank.

[0018] Furthermore, the upper layer of the double-layer stirring blades is a propeller-type blade, and the lower layer is a turbine-type blade, with a rotation speed range of 200-500 r / min. The main reactor is equipped with a first motor, which drives the double-layer stirring blades to rotate through a rotating shaft.

[0019] Furthermore, the defoaming spray assembly includes high-pressure nozzles densely arranged on the top of the filter box, the spray liquid is deionized water or low-concentration oxalic acid solution, and the spray pressure is 0.3-0.5 MPa.

[0020] Furthermore, a flow control valve is provided between the premixing tank and the main reactor. The valve body is made of polytetrafluoroethylene and has an acid resistance rating of ≥PH1.

[0021] Furthermore, the circulating water cooling jacket adopts a spiral coil structure with a coil spacing of 10-15mm and a cooling water flow rate of 1.5-2.0m / s.

[0022] Furthermore, the bottom of the filter box is provided with a detachable sedimentation tank, and the inner wall of the sedimentation tank is coated with a polyurethane anti-corrosion layer with a thickness of 0.5-1.0mm.

[0023] Furthermore, this design also includes a PLC control unit, which is connected to the metering pump, the first motor, the PID controller, and the flow control valve to realize the automatic adjustment of raw material ratio, stirring speed, and water temperature.

[0024] Furthermore, the premixing tank is equipped with a pH sensor to monitor the acidity and alkalinity of the solution in real time and feed it back to the PLC control unit.

[0025] Furthermore, a safety pressure relief valve is installed on the top of the main reactor, and the safety pressure relief threshold is set to 0.6-0.8 MPa.

[0026] Compared with the prior art, the beneficial effects of this utility model are:

[0027] This invention designs a modular system for producing oxalic acid solution for degreasing silicon materials, comprising a raw material preparation module, a multi-stage mixing module, a filtration and purification module, and a temperature control module. The raw material preparation, mixing, filtration, and temperature control modules are independently adjustable to adapt to different production scales. Automated control, with a PLC unit monitoring parameters throughout the process, reduces manual intervention. Safety redundancy, including pressure relief valves and corrosion-resistant designs, ensures long-term stable operation. This achieves efficient solution preparation and improved stability, meeting the industrial cleaning needs of silicon materials.

[0028] This invention overcomes traditional process bottlenecks through multi-stage mixing-filtration-temperature control technology. Chemical synergy: oxalic acid is compounded with a specific surfactant (rhamnolipid / polyethylene glycol monododecyl ether) to form a dynamic micelle structure, increasing silicone oil removal rate to over 99.5%. Physical enhancement: the synergistic effect of ultrasonic dispersion (frequency 20kHz) and double-layer stirring (shear rate > 500s⁻¹) reduces the standard deviation (σ) of the solution particle size distribution to below 0.8μm². Engineering optimization: three-stage gradient filtration (pore size 1μm → 0.5μm → 0.1μm) combined with defoaming spraying achieves a particle retention rate > 99.9% and a bubble density < 10. 2 pcs / cm 3 . Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structural layout of this utility model.

[0031] In the diagram: 1. Oxalic acid storage tank; 2. Surfactant addition unit; 3. Deionized water supply device; 4. Solenoid valve; 5. Metering pump; 6. Premixing tank; 7. Main reactor; 8. Stirring paddle; 9. Ultrasonic disperser; 10. Filter box; 11. Filter paper layer; 12. Ceramic filter plate; 13. Stainless steel microporous filter plate; 14. Circulating water-cooled jacket; 15. Temperature sensor; 16. PID controller; 17. Rhamnose lipolipide composition storage tank; 18. Polyethylene glycol monododecyl ether storage tank; 19. Weighing device; 20. Control valve; 21. Propeller blade; 22. Turbine blade; 23. First motor; 24. High-pressure nozzle; 25. Flow control valve; 26. Sedimentation tank; 27. PLC control unit; 28. pH sensor; 29. ​​Safety relief valve. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0033] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0034] Example 1

[0035] like Figure 1 As shown, a system for producing oxalic acid solution for degreasing silicon materials includes:

[0036] Raw material preparation module: It consists of oxalic acid storage tank 1, surfactant addition unit 2, and deionized water supply device 3. The three are connected to premix tank 6 through metering pump 5. This module completes the supply of each raw material. Solenoid valves 4 are installed on the connecting pipelines of oxalic acid storage tank 1, surfactant addition unit 2, deionized water supply device 3 and metering pump 5 to control the opening and closing of each branch.

[0037] Multi-stage mixing module: includes a premixing tank 6 and a main reaction vessel 7. The premixing tank 6 is equipped with a stirring paddle 8 and an ultrasonic disperser 9. After the material is initially mixed by the stirring paddle 8 and the ultrasonic disperser 9, the material is pumped into the main reaction vessel 7. The main reaction vessel 7 is equipped with double-layer stirring blades to further mix the material inside at high speed.

[0038] Filtration and purification module: includes a filter box 10, the outlet of the main reactor 7 is connected to the filter box 10, the filter box 10 is provided with a filter paper layer 11, a ceramic filter plate 12 and a stainless steel microporous filter plate 13 in sequence, and the top of the filter box 10 is provided with a defoaming spray assembly; after the material is mixed in the main reactor 7, it is passed through the filter and purification module to complete the filtration and purification.

[0039] Temperature control module: includes a circulating water cooling jacket 14 surrounding the main reactor 7 and a temperature sensor 15 installed inside the main reactor 7, and also includes a PID controller 16 installed on the side of the main reactor 7, which adjusts the water temperature.

[0040] Example 2

[0041] This embodiment is a further optimization and refinement of the structure of the surfactant addition unit 2 based on embodiment 1. Specifically, the surfactant addition unit 2 includes a rhamnolipid composition storage tank 17 and a polyethylene glycol monododecyl ether storage tank 18, which are mixed at a weight ratio of 1:2 and then added to the premixing tank 6. Specifically, the rhamnolipid composition storage tank 17 and the polyethylene glycol monododecyl ether storage tank 18 are arranged side by side, and their output ends are connected to a weighing device 19. Control valves 20 are respectively installed between their respective output ends and the weighing device 19. The materials of the two are weighed and premixed in the weighing device 19 (premixing here means weighing out the corresponding materials according to the ratio to complete premixing. For example, one material is first introduced into the weighing device 19, and after reaching the target amount, the other material is introduced. At this time, the sum of the weights of the two is measured, and after reaching the target amount, it is ready) before being introduced into the premixing tank 6.

[0042] Example 3

[0043] This embodiment is a further optimization and refinement of the structure of the main reactor 7 based on Embodiment 2, specifically as follows:

[0044] The upper layer of the double-layer stirring blades is a propeller-type blade 21, and the lower layer is a turbine-type blade 22. The rotation speed range is 200-500 r / min. The main reactor 7 is equipped with a first motor 23, which drives the double-layer stirring blades to rotate through a rotating shaft. At the same time, the materials in the main reactor 7 are stirred in layers and mixed and circulated, resulting in more uniform stirring and more thorough and rapid mixing.

[0045] In this embodiment, a flow control valve 25 is provided between the premixing tank 6 and the main reactor 7. The valve body is made of polytetrafluoroethylene (PTFE) with an acid resistance rating ≥ pH 1, ensuring precise metering. The circulating water cooling jacket 14 adopts a spiral coil structure with a coil spacing of 10-15 mm and a cooling water flow rate of 1.5-2.0 m / s, facilitating precise temperature control. A safety pressure relief valve 29 is also installed on the top of the main reactor 7, with a safety pressure relief threshold set at 0.6-0.8 MPa to protect the equipment during safe operation.

[0046] Example 4

[0047] This embodiment is a further optimization and refinement of the filtration and purification module structure based on Embodiment 3, specifically as follows:

[0048] The defoaming spray assembly includes high-pressure nozzles 24 densely arranged on the top of the filter box 10. The spray liquid is deionized water or a low-concentration oxalic acid solution, and the spray pressure is 0.3-0.5 MPa. It is understood that the various high-pressure nozzles 24 are connected by a pipeline network, and the pipeline network is externally connected to a power pump (not shown in the attached drawings, conventional technical means).

[0049] In this embodiment, the bottom of the filter box 10 is provided with a detachable sedimentation tank 26, which can be directly clamped to the bottom of the filter box 10 by interference fit. The inner wall of the sedimentation tank 26 is coated with a polyurethane anti-corrosion layer with a thickness of 0.5-1.0mm, which is used to collect impurities.

[0050] Example 5

[0051] This embodiment is a further optimization and refinement of the production system structure based on Embodiment 4, specifically as follows:

[0052] The oxalic acid solution production system for degreasing silicon materials described in this embodiment also includes a PLC control unit 27. The PLC control unit 27 is connected to the metering pump 5, the first motor 23, the PID controller 16, and the flow control valve 25, etc., to realize the automatic adjustment of raw material ratio, stirring speed and water temperature, etc., with a high degree of automation.

[0053] In this embodiment, the premixing tank 6 is equipped with a pH sensor 28 to monitor the acidity or alkalinity of the solution in real time and feed it back to the PLC control unit 27. That is, the pH sensor 28 is also connected to the PLC control unit 27 via signal connection.

[0054] Working principle:

[0055] Materials are stored in the raw material preparation module and supplied through the raw material preparation module. The materials are initially mixed in the premix tank 6 after being introduced into the main reactor 7 for thorough mixing. The mixed materials are then collected after being processed by the filtration and purification module.

[0056] Furthermore, in the description of this utility model, unless otherwise stated, the terms "multiple," "multiple roots," and "multiple groups" mean two or more, and "several," "several roots," and "several groups" mean one or more. In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used only for descriptive purposes and should not be construed as indicating or implying relative importance.

[0057] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A production system of an oxalic acid solution for silicon material decontamination, characterized by comprising: an oxalic acid solution production device; and a decontamination device. The application relates to a preparation device for preparing a high-concentration oxalic acid solution, which comprises the following parts: a raw material preparation module composed of an oxalic acid storage tank, a surfactant adding unit and a deionized water supply device, wherein the three parts are connected to a premixing tank through metering pumps; a multi-stage mixing module comprising a premixing tank and a main reaction kettle, wherein a stirring paddle and an ultrasonic disperser are arranged in the premixing tank, and double-layer stirring blades are arranged in the main reaction kettle to mix materials in the main reaction kettle at high speed; a filtering and purifying module comprising a filtering box, wherein the outlet of the main reaction kettle is connected to the filtering box, filter paper layers, ceramic filter plates and stainless steel microporous filter plates are sequentially arranged in the filtering box, and a defoaming spray assembly is arranged on the top of the filtering box; a temperature control module comprising a circulating water cooling interlayer surrounding the main reaction kettle and a temperature sensor arranged in the circulating water cooling interlayer, and a PID controller arranged on the side of the main reaction kettle, wherein the water temperature is adjusted through the PID controller.

2. The production system of claim 1, wherein: The surfactant adding unit comprises a rhamnolipid composition storage tank and a polyethylene glycol monododecyl ether storage tank, and the two parts are mixed at a weight ratio of 1:2 and then added into the premixing tank.

3. The production system of claim 1, wherein: The upper layer of the double-layer stirring blades is a propeller type blade, and the lower layer is a turbine type blade, and the rotating speed range is 200-500 r / min; a first motor is arranged on the main reaction kettle, and the double-layer stirring blades are driven to rotate by the first motor through a rotating shaft.

4. The production system of claim 1, wherein: The defoaming spray assembly comprises high-pressure nozzles densely arranged on the top of the filtering box, the spraying liquid is deionized water or a low-concentration oxalic acid solution, and the spraying pressure is 0.3-0.5 MPa.

5. The production system of claim 1, wherein: A flow control valve is arranged between the premixing tank and the main reaction kettle, and the valve body is made of polytetrafluoroethylene and has an acid resistance grade of greater than or equal to PH1.

6. The production system of claim 1, wherein: The circulating water cooling interlayer adopts a spiral coil structure, the coil spacing is 10-15 mm, and the cooling water flow speed is 1.5-2.0 m / s.

7. The production system of claim 1, wherein: A detachable sedimentation tank is arranged at the bottom of the filtering box, and a polyurethane anticorrosive layer is coated on the inner wall of the sedimentation tank and has a thickness of 0.5-1.0 mm.

8. The production system of claim 1, wherein: A PLC control unit is further arranged, the PLC control unit is signal-connected with the metering pumps, the first motor, the PID controller and the flow control valve, and the raw material ratio, the stirring speed and the water temperature can be automatically adjusted.

9. The production system of claim 8, wherein: A pH sensor is arranged in the premixing tank, the pH sensor can monitor the acidity and alkalinity of the solution in real time and feed back to the PLC control unit.

10. The production system of claim 1, wherein: A safety pressure relief valve is arranged on the top of the main reaction kettle, and the safety pressure relief threshold is set to 0.6-0.8 MPa.

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