Composite cutting fluid and method for multi-wire cutting of silicon carbide
By leveraging the chemical-mechanical synergy of composite cutting fluids, the problems of low cutting efficiency, poor quality, and instability in silicon carbide multiwire cutting are solved, achieving a highly efficient and stable cutting process, extending tool life, and improving machining quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YANTAI LIKAI SEMICONDUCTOR TECHNOLOGY CO LTD
- Filing Date
- 2026-02-06
- Publication Date
- 2026-05-15
AI Technical Summary
Existing silicon carbide multiwire cutting technology suffers from low cutting efficiency, poor processing quality, severe tool wear, and poor process stability. This is mainly due to insufficient cutting fluid performance, which fails to effectively manage heat and chips, leading to problems such as localized overheating, microcracks, and chip blockage in the cutting area.
A composite cutting fluid is used, which consists of an alkaline oxidizing compound, a composite surfactant, a nano thermal conductivity enhancer, and an anionic dispersion stabilizer. Through the synergistic effects of chemical softening, lubrication, thermal conduction, and dispersion, it reduces cutting force, forms a super-lubricating film, efficiently disperses chips, controls the temperature of the cutting zone, and ensures machining quality and stability.
It significantly improves cutting efficiency, reduces tool wear, improves processing quality, broadens the process window, enhances process stability, extends tool life, and avoids the risk of thermal damage and wire breakage.
Smart Images
Figure CN122038031A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor material processing technology, and in particular to a composite cutting fluid for silicon carbide multi-wire cutting and its application. Background Technology
[0002] Silicon carbide, a key third-generation semiconductor material, typically requires multi-wire cutting to fabricate wafers from its ingots. During multi-wire cutting using diamond wire saws, cutting fluid plays a crucial role in cooling, lubrication, and chip removal.
[0003] In existing technologies, cutting fluids used for silicon carbide cutting primarily rely on physical abrasion, utilizing diamond abrasive grains to mechanically remove the high-hardness silicon carbide. This method presents several problems. For instance, the enormous cutting force leads to low cutting efficiency and exacerbates wear on the diamond wire. The high cutting stress can also easily introduce microcracks and dislocations on the wafer surface and subsurface, affecting the final yield. Furthermore, the large amount of heat and micro-powder chips generated during the cutting process are difficult to manage effectively. Traditional cutting fluids have limited thermal conductivity and dispersion capabilities, easily leading to localized overheating in the cutting area and causing thermal damage. Chips also tend to agglomerate and clog the kerf, scratching the workpiece surface, resulting in a narrow process window and poor stability.
[0004] Although some technical solutions attempt to introduce alkaline substances and oxidants into cutting fluids to assist cutting and soften the material surface through chemical action, these solutions often fail to systematically solve the problem of matching the chemical reaction rate with the local environment (especially temperature) in the cutting zone, and also fail to simultaneously take into account interface lubrication and chip dispersion. Therefore, their effectiveness is limited and cannot meet the urgent need for efficient, high-quality and high-stability processing of silicon carbide. Summary of the Invention
[0005] The purpose of this invention is to provide a composite cutting fluid for silicon carbide multi-wire cutting and its application, so as to solve the technical problems of low cutting efficiency, poor processing quality, severe tool wear and poor process stability caused by insufficient cutting fluid performance in the prior art.
[0006] To achieve the above objectives, the present invention provides a composite cutting fluid for silicon carbide multi-wire cutting, characterized in that it is composed of the following components mixed in weight percentages: alkaline oxidizing compound agent: 0.8-2.0 wt%; composite surfactant: 0.06-0.13 wt%; nano thermal conductivity enhancer: 0.07-0.15 wt%; anionic dispersion stabilizer: 0.15 wt%; and base liquid: the balance being deionized water.
[0007] Optionally, the alkaline oxidizing compound is composed of ammonium persulfate and potassium hydroxide.
[0008] Optionally, the content of ammonium persulfate is 0.3-0.8 wt%, and the content of potassium hydroxide is 0.5-1.2 wt%.
[0009] Optionally, the composite surfactant is composed of a perfluoropolyether carboxylate and a polyether-modified silicone oil.
[0010] Optionally, the content of the perfluoropolyether carboxylate is 0.01-0.03 wt%, and the content of the polyether-modified silicone oil is 0.05-0.1 wt%.
[0011] Optionally, the nano-thermal conductivity enhancer is composed of boron nitride nanotubes and alumina nanosheets.
[0012] Optionally, the content of boron nitride nanotubes is 0.02-0.05 wt%, and the content of alumina nanosheets is 0.05-0.1 wt%.
[0013] Optionally, the anionic dispersion stabilizer is composed of ammonium polyacrylate and alkylphenol polyoxyethylene ether.
[0014] Optionally, the content of the ammonium polyacrylate is 0.1 wt%, and the content of the alkylphenol polyoxyethylene ether is 0.05 wt%.
[0015] Optionally, the cutting fluid has a pH value of 10.5-11.5.
[0016] In a preferred embodiment of this application, the alkaline oxidizing compound agent comprises 0.5 wt% ammonium persulfate and 0.8 wt% potassium hydroxide, the composite surfactant comprises 0.02 wt% perfluoropolyether carboxylate and 0.08 wt% polyether-modified silicone oil, the nano-thermal conductivity enhancer comprises 0.03 wt% boron nitride nanotubes and 0.08 wt% alumina nanosheets, and the anionic dispersion stabilizer comprises 0.1 wt% ammonium polyacrylate and 0.05 wt% alkylphenol polyoxyethylene ether.
[0017] In a preferred embodiment of this application, the alkaline oxidizing compound agent comprises 0.8 wt% ammonium persulfate and 1.2 wt% potassium hydroxide, the composite surfactant comprises 0.015 wt% perfluoropolyether carboxylate and 0.06 wt% polyether-modified silicone oil, the nano-thermal conductivity enhancer comprises 0.025 wt% boron nitride nanotubes and 0.07 wt% alumina nanosheets, and the anionic dispersion stabilizer comprises 0.1 wt% ammonium polyacrylate and 0.05 wt% alkylphenol polyoxyethylene ether.
[0018] In a preferred embodiment of this application, the alkaline oxidizing compound agent comprises 0.4 wt% ammonium persulfate and 0.6 wt% potassium hydroxide, the composite surfactant comprises 0.03 wt% perfluoropolyether carboxylate and 0.1 wt% polyether-modified silicone oil, the nano-thermal conductivity enhancer comprises 0.03 wt% boron nitride nanotubes and 0.08 wt% alumina nanosheets, and the anionic dispersion stabilizer comprises 0.1 wt% ammonium polyacrylate and 0.05 wt% alkylphenol polyoxyethylene ether.
[0019] The present invention also provides a method for silicon carbide multi-wire cutting, characterized in that it includes the step of applying the composite cutting fluid of claim 1 to the cutting area between the diamond wire and the silicon carbide workpiece.
[0020] The present invention also provides a method for preparing the composite cutting fluid according to claim 1, characterized by comprising the following steps: dissolving an anionic dispersion stabilizer in deionized water as a base fluid; adding and dissolving components of an alkaline oxidizing compound; adding a nano-thermal conductivity enhancer and dispersing it; and adding a composite surfactant.
[0021] Compared with existing technologies, the present invention has the following beneficial effects: The composite cutting fluid provided by the present invention forms a chemical softening layer on the silicon carbide surface through an alkaline oxidizing compound, achieving chemical-mechanical synergistic removal, significantly reducing cutting force, and thus greatly improving cutting efficiency; the composite surfactant forms a super-lubricating film at the cutting interface, which, combined with the reduction of cutting force, effectively inhibits subsurface damage and edge chipping. At the same time, the anionic dispersion stabilizer ensures efficient dispersion and discharge of chips, avoiding scratches on the workpiece surface, thereby significantly improving processing quality; the super-lubricating effect and the reduction of cutting force also reduce the wear and shedding of diamond abrasive grains, significantly extending the tool's service life; in addition, the nano-thermal conductivity enhancer significantly improves the thermal conductivity of the cutting fluid, enabling precise stabilization of the cutting zone temperature within the optimal temperature range for chemical reaction, avoiding thermal damage and wire breakage risks caused by local overheating, widening the process window, and enhancing the stability and reliability of the entire cutting process. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of this application 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 application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a schematic diagram of the structure of a silicon carbide multi-wire cutting system provided in an embodiment of this application;
[0024] Figure 2 This is a flowchart illustrating a method for preparing a composite cutting fluid, as provided in an embodiment of this application.
[0025] Figure reference numerals: 10-Multi-wire cutting machine; 20-Diamond wire; 30-Silicon carbide workpiece; 40-Cutting fluid circulation system; 41-Reservoir tank; 42-Pump; 43-Nozzle; S101-Add anionic dispersant stabilizer to deionized water and stir to dissolve; S102-Add potassium hydroxide and ammonium persulfate and stir to dissolve; S103-Add nano-thermal conductivity enhancer and perform high-speed shearing / ultrasonic dispersion; S104-Add composite surfactant and stir at low speed; S105-Detect and adjust the pH value to 10.5-11.5; S106-Let stand to defoam and obtain the finished product. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.
[0027] Example 1
[0028] This embodiment provides a composite cutting fluid for silicon carbide multi-wire cutting. Its formulation is designed to achieve a balanced and synergistic effect of four major functions: chemical softening, friction reduction and lubrication, thermal conductivity and temperature control, and chip removal and anti-clogging, in order to achieve comprehensive optimization of cutting efficiency, processing quality and tool life.
[0029] In one embodiment of this application, the composite cutting fluid is composed of the following components mixed in weight percentages: Alkaline oxidizing agent: 1.3 wt%, comprising 0.5 wt% ammonium persulfate and 0.8 wt% potassium hydroxide; Composite surfactant: 0.1 wt%, comprising 0.02 wt% perfluoropolyether carboxylate and 0.08 wt% polyether-modified silicone oil; Nano-thermal conductivity enhancer: 0.11 wt%, comprising 0.03 wt% boron nitride nanotubes and 0.08 wt% alumina nanosheets; Anionic dispersion stabilizer: 0.15 wt%, comprising 0.1 wt% ammonium polyacrylate and 0.05 wt% alkylphenol polyoxyethylene ether; Base liquid: balance, deionized water.
[0030] Please see Figure 2 The document illustrates a flowchart of a method for preparing a composite cutting fluid according to an embodiment of this application. The preparation process of the composite cutting fluid in this embodiment strictly follows this flowchart, and the specific steps are as follows:
[0031] Step S101: Add an anionic dispersion stabilizer to the deionized water used as the base liquid and stir to dissolve. Specifically, add deionized water to a clean reactor according to the formula, turn on the stirrer, and slowly add 0.1 wt% ammonium polyacrylate and 0.05 wt% alkylphenol polyoxyethylene ether at room temperature and pressure. It is understood that ammonium polyacrylate, as a high-molecular-weight polymer electrolyte, has molecular chains that extend in water, providing a preliminary charge stabilization basis for subsequently added nanoparticles and generated chips through the electrostatic repulsion of carboxylate groups. Alkylphenol polyoxyethylene ether, as a nonionic surfactant, has a hydrophilic end that is compatible with water, while its hydrophobic end can adsorb onto the particle surface, forming a steric hindrance layer. The combination of these two provides a dual stabilization mechanism of electrostatic repulsion and steric hindrance for the subsequent nanoparticles and silicon carbide microparticles generated during the cutting process, ensuring uniform dispersion throughout the cutting fluid system without aggregation or sedimentation. In this step, the stirring rate can be set to 300-500 rpm, and stirring should be continued for about 20 minutes until both stabilizers are completely dissolved and the solution is clear and transparent.
[0032] In step S102, potassium hydroxide and ammonium persulfate are added and stirred until dissolved. While maintaining stirring, 0.8 wt% of potassium hydroxide granules are added to the reactor in batches. After complete dissolution and heat release, the solution temperature may rise slightly. It should be noted that potassium hydroxide not only provides the necessary strongly alkaline environment for the subsequent oxidation reaction, but its potassium ions may also participate in the chemical reaction on the silicon carbide surface. Subsequently, 0.5 wt% of ammonium persulfate powder is slowly added to the solution while continuing to stir. As a strong oxidant, ammonium persulfate decomposes under alkaline conditions and the subsequent high temperature catalysis to produce highly reactive sulfate radicals, which are the key substances for achieving chemical softening of the silicon carbide surface. This step requires ensuring that both chemicals are completely dissolved and the solution becomes clear again, with stirring time of approximately 30 minutes.
[0033] Step S103: Add a nano-thermal conductivity enhancer and perform high-speed shearing or ultrasonic dispersion. Mix 0.03 wt% boron nitride nanotubes and 0.08 wt% alumina nanosheets, then add them to the above solution. In this embodiment, the boron nitride nanotubes (BNNTs) are multi-walled boron nitride nanotubes (MW-BNNTs), with a diameter controlled at 10-50 nm and a length of 5-20 μm. The resulting nanotubes have an aspect ratio greater than 100, more preferably in the range of 200-1000. For the alumina nanosheets, a thickness of 40-60 nm is preferred. Due to the large specific surface area of nanomaterials, they are prone to aggregation; therefore, high-energy dispersion methods must be employed. As an optional implementation, this embodiment uses a high-speed shear disperser, setting the rotation speed to 8000-10000 rpm, and performing high-speed shearing treatment for 45 minutes. Boron nitride nanotubes possess extremely high axial thermal conductivity and excellent electrical insulation. Their one-dimensional tubular structure facilitates the construction of efficient heat conduction pathways in cutting fluids. Alumina nanosheets, on the other hand, exhibit good dispersibility and high thermal conductivity. Their two-dimensional sheet-like structure can serve as "nodes" in the heat conduction network, connecting different boron nitride nanotubes to form a three-dimensional heat conduction network framework, systematically improving the overall macroscopic thermal conductivity of the liquid. Through high-energy dispersion treatment, it is ensured that these two types of nanoparticles are fully deagglomerated and effectively coated by the previously added anionic dispersion stabilizer, stably suspending in the base fluid at nanoscale size.
[0034] In step S104, the composite surfactant is added and stirred at a low speed. After the nanoparticles are dispersed, the stirring speed is reduced to a low speed of 100-200 rpm to avoid generating excessive foam. At this point, 0.02 wt% of perfluoropolyether carboxylate and 0.08 wt% of polyether-modified silicone oil are added to the mixture.
[0035] In this embodiment, the perfluoropolyether carboxylate is preferably used. Type, where n is an integer from 1 to 10.
[0036] Perfluoropolyether carboxylates are high-performance fluorinated surfactants with extremely low surface energy at their fluorocarbon chain ends, allowing them to preferentially adsorb onto the surfaces of diamond wire and silicon carbide workpieces, forming a dense, low-friction lubricating film. Polyether-modified silicone oil acts as an auxiliary lubricant; its siloxane backbone provides lubrication, while the polyether side chains enhance its solubility and stability in water-based systems. It also works synergistically with perfluoropolyether carboxylates to repair wear on the lubricating film during use, forming a dynamically stable, super-lubricating interface. Stir at low speed for approximately 20 minutes to ensure both surfactants are fully dissolved and evenly distributed.
[0037] Step S105: Detect and adjust the pH value to 10.5-11.5. Detect the pH value of the mixture using a calibrated pH meter. Due to the addition of potassium hydroxide, the pH value is usually already within the target range. In this embodiment, the final measured and confirmed pH value is 11.0. If the pH value deviates from the target range, it can be fine-tuned using a dilute potassium hydroxide solution or a dilute acidic solution (such as dilute sulfuric acid). Maintaining the pH value within the preferred range of 10.5-11.5 is crucial for ensuring that ammonium persulfate efficiently and stably generates oxidizing free radicals at high cutting temperatures, while avoiding excessive corrosion of the equipment.
[0038] Step S106: Allow to stand and defoam to obtain the finished product. Stop stirring, transfer the prepared composite cutting fluid to the finished product tank, and let it stand for 2-4 hours to allow the tiny air bubbles introduced during stirring and dispersion to escape naturally, thereby obtaining a uniform and stable finished composite cutting fluid.
[0039] Please see Figure 1 The diagram illustrates a structural schematic of a silicon carbide multi-wire cutting system provided in an embodiment of this application. In practical applications, the composite cutting fluid prepared above is used... Figure 1 The system shown primarily comprises a multi-wire cutting machine 10 and a cutting fluid circulation system 40. Inside the multi-wire cutting machine 10, diamond wire 20 wound on guide wheels (not shown) reciprocates at extremely high speeds to cut a silicon carbide workpiece 30 that is firmly clamped.
[0040] The cutting fluid circulation system 40 is responsible for the supply, cooling, and filtration of the cutting fluid. The composite cutting fluid of this embodiment, stored in the reservoir 41, is pressurized by the pump 42 and delivered via pipeline to the nozzle 43 located above the cutting area. The nozzle 43 continuously and precisely sprays the cutting fluid in the form of a mist or curtain into the narrow kerf formed between the diamond wire 20 and the silicon carbide workpiece 30.
[0041] In this cutting area, the components of the composite cutting fluid in this embodiment work synergistically. First, the high-speed friction of the diamond wire 20 against the silicon carbide workpiece 30 generates a large amount of frictional heat, causing the local temperature at the cutting point to rise rapidly to 250-300°C. At this temperature and in the alkaline environment provided by potassium hydroxide, ammonium persulfate decomposes rapidly, generating highly reactive sulfate radicals. These radicals attack the Si-C covalent bonds of silicon carbide, oxidizing its surface into a loosely structured, significantly reduced-hardness amorphous hydrated silica softening layer. Correspondingly, the diamond abrasive grains on the diamond wire 20 no longer face the high-hardness silicon carbide crystals, but rather the relatively soft oxide layer, achieving a transformation from purely physical grinding ("hard against hard") to chemical-mechanical synergistic removal ("hard cutting soft"), thus significantly reducing the cutting force.
[0042] Simultaneously, the molecules of the composite surfactant rapidly adsorb onto the metal surface of the diamond wire 20 and the surface of the silicon carbide workpiece 30, forming a dynamically balanced, low-shear-strength nanoscale bimolecular lubricating film. This lubricating film effectively isolates the diamond abrasive grains from direct contact with the workpiece, transforming the "ploughing" action during the cutting process into a smoother "slipping" removal, greatly reducing the coefficient of friction, energy dissipation, and wear of the diamond abrasive grains.
[0043] The heat generated during cutting, including frictional heat and chemical reaction heat, is efficiently dissipated by the nano-thermal conductivity enhancer in the cutting fluid. The three-dimensional thermally conductive network composed of boron nitride nanotubes and alumina nanosheets makes the thermal conductivity of the cutting fluid much higher than that of the base fluid, enabling rapid transfer of heat from the cutting point to the flowing cutting fluid bulk, which is then carried away by the circulation system for cooling. This allows the temperature of the cutting zone to be precisely stabilized within the 250-300℃ range, which is most favorable for the chemical softening reaction, avoiding the risk of material thermal damage or wire breakage due to localized overheating.
[0044] The silicon carbide micropowder and softened layer debris generated during the cutting process are immediately coated by the molecules of the anionic dispersion stabilizer once they enter the cutting fluid. Through electrostatic repulsion and steric hindrance, these micron- and nano-sized particles are prevented from approaching each other and agglomerating, and flow out of the kerf in a stable suspended state with the cutting fluid. After use, the cutting fluid carries these chips back to the reservoir 41. After the solid particles are removed by the filtration system (not shown in the figure), the clean cutting fluid is pumped back into the circulation system by pump 42, thus achieving an efficient and clean chip removal process and preventing chips from clogging the kerf or scratching the surface of the processed wafer.
[0045] Through the aforementioned synergistic effect, compared with the use of traditional cutting fluids, the cutting rate of silicon carbide multi-wire cutting using the composite cutting fluid of this embodiment can be increased from 1.2 mm / min to 1.7 mm / min, an increase of approximately 41.7%; the surface roughness Ra of the cut wafer can be reduced from 15.8 nm to 8.2 nm, an improvement of approximately 48%; the total thickness variation (TTV) can be improved from 12.5 μm to 7.1 μm, an improvement of approximately 43%; and the wear rate of diamond wire 20 can be reduced from 0.85 μm / km to 0.58 μm / km, a reduction of approximately 31.8%, significantly extending tool life. The raw material specifications used in Examples 2-4 are the same as in Example 1.
[0046] Example 2
[0047] This embodiment provides a modified version of a composite cutting fluid, designed to achieve the ultimate material removal rate and cutting speed by enhancing chemical oxidation.
[0048] As an optional implementation, the components and weight percentages of the composite cutting fluid are as follows: Alkaline oxidizing agent: 2.0 wt%, containing 0.8 wt% ammonium persulfate and 1.2 wt% potassium hydroxide; Composite surfactant: 0.075 wt%, containing 0.015 wt% perfluoropolyether carboxylate and 0.06 wt% polyether-modified silicone oil; Nano-thermal conductivity enhancer: 0.095 wt%, containing 0.025 wt% boron nitride nanotubes and 0.07 wt% alumina nanosheets; Anionic dispersion stabilizer: 0.15 wt%, containing 0.1 wt% ammonium polyacrylate and 0.05 wt% alkylphenol polyoxyethylene ether; Base fluid: balance, deionized water.
[0049] The cutting fluid preparation method in this embodiment is basically the same as that in Example 1, and also follows the same procedure. Figure 2 The process is illustrated. In step S102, higher concentrations of potassium hydroxide (1.2 wt%) and ammonium persulfate (0.8 wt%) were added, resulting in a more alkaline solution and a higher concentration of oxidant. Accordingly, in step S105, the final pH value was adjusted and confirmed to be 11.4, which is within the preferred range of 10.5-11.5, and the higher alkalinity is more conducive to activating the oxidative activity of ammonium persulfate. The concentrations of other components were adjusted accordingly within the scope of this application to complement this enhanced oxidation.
[0050] In application Figure 1 In the silicon carbide multi-wire cutting system shown, because the concentration of the alkaline oxide compound reaches the upper limit of its preferred range, the rate of the chemical softening reaction is significantly accelerated under the high temperature and high pressure at the cutting point. That is, a thicker or looser softened layer can be formed on the surface of the silicon carbide workpiece 30 per unit time. Therefore, under the same diamond wire speed and tension, the diamond abrasive grains can remove more material with each pass over the workpiece surface, which directly translates into a higher macroscopic cutting feed rate.
[0051] Although this embodiment sacrifices some lubrication and thermal conductivity for extreme speed, the content of its composite surfactant, nano-thermal conductivity enhancer, and anionic dispersion stabilizer remains within an effective range. Therefore, compared to traditional technologies, it still has significant advantages in terms of machining quality, tool life, and process stability. Experimental results show that using the composite cutting fluid of this embodiment, the cutting rate can reach a maximum of 1.9 mm / min, an improvement of over 58% compared to traditional processes.
[0052] This embodiment demonstrates that by adjusting the concentration of the alkaline oxidizing agent, the cutting rate can be effectively controlled to meet specific efficiency requirements in different production scenarios. This formulation also supports the upper limit of the range of alkaline oxidizing agents and their component contents as stated in the claims.
[0053] Example 3
[0054] Alternatively, in another embodiment, a variant of the composite cutting fluid is provided, which is designed to minimize mechanical damage during the cutting process by enhancing the anti-friction and lubrication properties of the interface, thereby achieving the best machining surface quality and the lowest tool wear rate.
[0055] In this embodiment, the components and weight percentages of the composite cutting fluid are as follows: Alkaline oxidizing agent: 1.0 wt%, comprising 0.4 wt% ammonium persulfate and 0.6 wt% potassium hydroxide; Composite surfactant: 0.13 wt%, comprising 0.03 wt% perfluoropolyether carboxylate and 0.1 wt% polyether-modified silicone oil; Nano-thermal conductivity enhancer: 0.11 wt%, comprising 0.03 wt% boron nitride nanotubes and 0.08 wt% alumina nanosheets; Anionic dispersion stabilizer: 0.15 wt%, comprising 0.1 wt% ammonium polyacrylate and 0.05 wt% alkylphenol polyoxyethylene ether; Base fluid: balance, deionized water.
[0056] The cutting fluid preparation method in this embodiment also follows... Figure 2 The process is shown below. The key difference lies in step S104, where a composite surfactant with a total content of 0.13 wt% is added. The components, perfluoropolyether carboxylate (0.03 wt%) and polyether-modified silicone oil (0.1 wt%), are both at the upper limit of their respective preferred ranges. Simultaneously, to focus on inhibiting mechanical damage, the concentration of the alkaline oxidizing agent is set at a relatively mild level (total content 1.0 wt%). In step S105, the final pH value is adjusted and confirmed to be 10.8, within the preferred range of 10.5-11.5.
[0057] When this cutting fluid is applied Figure 1 During the cutting system shown, a higher concentration of composite surfactant molecules forms a denser, stronger, and faster-healing bimolecular lubricating film on the surfaces of the diamond wire 20 and the silicon carbide workpiece 30. This super-lubricating film can more effectively withstand the normal pressure and tangential shear force of the diamond abrasive grains, greatly buffering the direct hard contact between the abrasive grains and the workpiece surface. The mechanical action during the cutting process is more manifested as smooth "slippage" on the lubricating film, rather than violent "plowing" and "scraping," thus significantly reducing the stress acting on the silicon carbide lattice.
[0058] This super-lubricating effect brings two significant benefits. Firstly, due to the substantial reduction in cutting stress, the depth and density of subsurface damage to the wafer introduced by mechanical action (such as microcracks and dislocations) are effectively suppressed, and edge chipping is significantly reduced, resulting in optimal machining quality. Experimental data show that using the cutting fluid of this embodiment, the wafer surface roughness Ra can be reduced to 7.5 nm, and the total thickness variation (TTV) can be reduced to 6.8 μm. Secondly, the impact and wear on the diamond abrasive grains are minimized, and the probability of abrasive grain breakage and detachment from the diamond wire matrix is greatly reduced. Therefore, the service life of the diamond wire 20 is maximized, with a wear rate as low as 0.51 μm / km.
[0059] This embodiment demonstrates that increasing the concentration of the composite surfactant can significantly improve processing quality and tool life, thus meeting the requirements of applications with extremely high wafer quality. This formulation supports the upper limit of the range of composite surfactants and their component contents as stated in the claims.
[0060] Example 4
[0061] This embodiment provides another variation of the composite cutting fluid, which focuses on enhancing the thermal management capabilities of the cutting fluid to ensure that the entire process remains highly stable under long-term, high-load continuous cutting conditions, and to prevent accidents caused by heat accumulation.
[0062] In this embodiment, the components and weight percentages of the composite cutting fluid are as follows: Alkaline oxidizing agent: 1.1 wt%, comprising 0.4 wt% ammonium persulfate and 0.7 wt% potassium hydroxide; Composite surfactant: 0.09 wt%, comprising 0.02 wt% perfluoropolyether carboxylate and 0.07 wt% polyether-modified silicone oil; Nano-thermal conductivity enhancer: 0.15 wt%, comprising 0.05 wt% boron nitride nanotubes and 0.1 wt% alumina nanosheets; Anionic dispersion stabilizer: 0.15 wt%, comprising 0.1 wt% ammonium polyacrylate and 0.05 wt% alkylphenol polyoxyethylene ether; Base fluid: balance, deionized water.
[0063] The cutting fluid preparation method in this embodiment also follows... Figure 2The process is illustrated below. Its notable feature is the addition of a nano-thermal conductivity enhancer in step S103, with a total content of 0.15 wt%, wherein the contents of boron nitride nanotubes (0.05 wt%) and alumina nanosheets (0.1 wt%) both reach the upper limit of their respective preferred ranges. The contents of other components are set at balanced levels. In step S105, the final pH value is adjusted and confirmed to be 10.9, within the preferred range of 10.5-11.5.
[0064] When this cutting fluid is applied Figure 1 The cutting system shown here has the most prominent advantage in its superior thermal management capabilities. Higher concentrations of boron nitride nanotubes and alumina nanosheets construct a denser and more efficient three-dimensional heat-conducting network in the base fluid. During long-duration, high-feed-rate continuous cutting, a huge and continuous heat flow is generated. The cutting fluid in this embodiment, with its extremely high thermal conductivity, can rapidly conduct the Joule heat generated at the cutting point into the flowing liquid and quickly remove it from the cutting zone through the cutting fluid circulation system 40.
[0065] This powerful heat dissipation capability ensures that the local temperature in the cutting zone is consistently and precisely controlled within the optimal chemical reaction range of 250-300℃, preventing drastic temperature fluctuations or continuous temperature increases. On one hand, the stable temperature guarantees a stable chemical softening reaction rate, thus ensuring consistent cutting efficiency and processing quality. On the other hand, it effectively prevents local temperatures from exceeding the thermal damage threshold of silicon carbide material, avoiding thermal cracking or warping of the wafer due to excessive thermal stress. More importantly, for the diamond wire 20 itself, it avoids a decrease in wire strength caused by localized overheating, thereby significantly reducing the risk of wire breakage under high tension.
[0066] Therefore, while the composite cutting fluid of this embodiment may not be optimal in terms of a single cutting speed or surface quality indicator, it offers the highest process stability, reliability, and yield during long-term continuous production. This embodiment is particularly suitable for scenarios with stringent requirements for process stability and low failure rates, such as large-scale, automated production lines. This formulation supports the upper limit of the range of nano-thermal conductivity enhancers and their component contents as stated in the claims.
[0067] Comparative Example 1
[0068] To verify the beneficial effects of the composite cutting fluid provided in this application, a comparative example was set up. Comparative Example 1 uses a traditional water-based cutting fluid that does not contain the four core functional compounding agents described in this application. Its components are only: 10 wt% ethylene glycol, 1 wt% triethanolamine (as a corrosion inhibitor), and the balance is deionized water.
[0069] Using the same multi-wire cutting machine 10, diamond wire 20, silicon carbide workpiece 30, and process parameters (such as line speed, tension, etc.) as in Examples 1-4, a cutting experiment was conducted using the conventional cutting fluid of Comparative Example 1.
[0070] Experimental results show that, due to the lack of chemical softening, the cutting process relies entirely on the physical grinding of diamond abrasive grains, resulting in enormous cutting forces and a cutting feed rate that can only reach 1.2 mm / min. Without effective lubrication, the friction coefficient is high, leading to severe wear of the diamond wire 20, with a wear rate as high as 0.85 μm / km. The enormous cutting stress causes significant damage to both the wafer surface and subsurface, resulting in a surface roughness Ra of 15.8 nm and a total thickness change (TTV) of 12.5 μm after cutting. Furthermore, due to the poor thermal conductivity of the cutting fluid and the absence of an effective dispersant, chip agglomeration was observed during the cutting process, posing a risk of localized overheating and poor process stability.
[0071] Performance Comparison
[0072] The performance test data of Examples 1-4 and Comparative Example 1 are summarized in the table below:
[0073] project Comparative Example 1 Example 1 (Balanced Type) Example 2 (High-speed type) Example 3 (High-Quality Type) Example 4 (High Stability Type) Alkaline oxidizing compound (wt%) 0 1.3 2.0 1.0 1.1 Complex surfactant (wt%) 0 0.1 0.075 0.13 0.09 Nano thermal conductivity enhancer (wt%) 0 0.11 0.095 0.11 0.15 Anionic dispersion stabilizer (wt%) 0 0.15 0.15 0.15 0.15 Cutting rate (mm / min) 1.2 1.7 1.9 1.6 1.65 Surface roughness Ra (nm) 15.8 8.2 9.5 7.5 8.5 Total thickness variation (TTV) (μm) 12.5 7.1 8.0 6.8 7.3 Wire saw wear rate (μm / km) 0.85 0.58 0.65 0.51 0.55
[0074] The comparison in the table above clearly shows that the composite cutting fluids provided in Examples 1-4 of this application, whether aimed at balanced performance or enhanced for specific properties, comprehensively and significantly outperform traditional cutting fluids in key indicators such as cutting rate, surface quality (Ra and TTV), and tool life (wire saw wear rate). This fully demonstrates that the four-component synergistic technical solution proposed in this application, consisting of an alkaline oxidizing compound, a composite surfactant, a nano-thermal conductivity enhancer, and an anionic dispersion stabilizer, can effectively solve the problems in the prior art and bring significant beneficial effects.
[0075] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A composite cutting fluid for silicon carbide multi-wire cutting, characterized in that, It is composed of the following components mixed in weight percentage: Alkaline oxidizing compound: 0.8-2.0 wt%; Composite surfactant: 0.06-0.13 wt%; Nano-thermal conductivity enhancer: 0.07-0.15 wt%; Anionic dispersion stabilizer: 0.1-0.2 wt%; and Base solution: The remainder is deionized water.
2. The composite cutting fluid according to claim 1, characterized in that, The alkaline oxidizing compound is composed of ammonium persulfate and potassium hydroxide; The composite surfactant is composed of perfluoropolyether carboxylate and polyether-modified silicone oil; The nano-thermal conductivity enhancer is composed of boron nitride nanotubes and alumina nanosheets; The anionic dispersion stabilizer is composed of ammonium polyacrylate and alkylphenol polyoxyethylene ether.
3. The composite cutting fluid according to claim 2, characterized in that, The ammonium persulfate comprises 0.3-0.8 wt% by weight; the potassium hydroxide comprises 0.5-1.2 wt% by weight; the perfluoropolyether carboxylate comprises 0.01-0.03 wt% by weight; the polyether-modified silicone oil comprises 0.05-0.1 wt% by weight; the boron nitride nanotubes comprises 0.02-0.05 wt% by weight; the alumina nanosheets comprises 0.05-0.1 wt% by weight; the ammonium polyacrylate comprises 0.1 wt% by weight; and the alkylphenol polyoxyethylene ether comprises 0.05 wt% by weight.
4. The composite cutting fluid according to any one of claims 1 to 3, characterized in that, The pH value of the composite cutting fluid is 10.5-11.
5.
5. The composite cutting fluid according to claim 2, characterized in that, The perfluoropolyether carboxylate is Type, where n is an integer from 1 to 10.
6. The composite cutting fluid according to claim 2, characterized in that, The alumina nanosheets have a thickness of 40-60 nm; the boron nitride nanotubes are multi-walled boron nitride nanotubes with a diameter of 10-50 nm, a length of 5-20 μm, and an aspect ratio greater than 100.
7. The composite cutting fluid according to claim 2, characterized in that, The ammonium persulfate has a weight percentage of 0.8 wt%, and the potassium hydroxide has a weight percentage of 1.2 wt%.
8. The composite cutting fluid according to claim 2, characterized in that, The perfluoropolyether carboxylate has a weight percentage of 0.03 wt%, and the polyether-modified silicone oil has a weight percentage of 0.1 wt%.
9. A method for preparing a composite cutting fluid, characterized in that, Includes the following steps: While stirring, a measured amount of deionized water is added to the reactor; Add the anionic dispersion stabilizer sequentially and stir until completely dissolved; Add potassium hydroxide, stir to dissolve, then add ammonium persulfate and continue stirring until the system is clear; The nano-thermal conductivity enhancer was added to the system and the system was dispersed until the nanoparticles were uniformly dispersed. Add the compound surfactant and stir at low speed until it is fully dissolved.
10. The preparation method according to claim 9, characterized in that, The dispersion process is performed by high-speed shearing or ultrasonic dispersion, with a processing time of 30-60 minutes.